1 /*
2 * Copyright (c) 2001, 2016, 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/concurrentMarkThread.inline.hpp"
30 #include "gc/g1/g1CollectedHeap.inline.hpp"
31 #include "gc/g1/g1CollectorState.hpp"
32 #include "gc/g1/g1ConcurrentMark.inline.hpp"
33 #include "gc/g1/g1HeapVerifier.hpp"
34 #include "gc/g1/g1OopClosures.inline.hpp"
35 #include "gc/g1/g1CardLiveData.inline.hpp"
36 #include "gc/g1/g1Policy.hpp"
37 #include "gc/g1/g1StringDedup.hpp"
38 #include "gc/g1/heapRegion.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.hpp"
56 #include "runtime/handles.inline.hpp"
57 #include "runtime/java.hpp"
58 #include "runtime/prefetch.inline.hpp"
59 #include "services/memTracker.hpp"
60 #include "utilities/growableArray.hpp"
61
62 // Concurrent marking bit map wrapper
63
64 G1CMBitMapRO::G1CMBitMapRO(int shifter) :
65 _bm(),
66 _shifter(shifter) {
67 _bmStartWord = 0;
68 _bmWordSize = 0;
69 }
70
71 HeapWord* G1CMBitMapRO::getNextMarkedWordAddress(const HeapWord* addr,
72 const HeapWord* limit) const {
73 // First we must round addr *up* to a possible object boundary.
74 addr = (HeapWord*)align_size_up((intptr_t)addr,
75 HeapWordSize << _shifter);
76 size_t addrOffset = heapWordToOffset(addr);
77 assert(limit != NULL, "limit must not be NULL");
78 size_t limitOffset = heapWordToOffset(limit);
79 size_t nextOffset = _bm.get_next_one_offset(addrOffset, limitOffset);
80 HeapWord* nextAddr = offsetToHeapWord(nextOffset);
81 assert(nextAddr >= addr, "get_next_one postcondition");
82 assert(nextAddr == limit || isMarked(nextAddr),
83 "get_next_one postcondition");
84 return nextAddr;
85 }
86
87 #ifndef PRODUCT
88 bool G1CMBitMapRO::covers(MemRegion heap_rs) const {
89 // assert(_bm.map() == _virtual_space.low(), "map inconsistency");
90 assert(((size_t)_bm.size() * ((size_t)1 << _shifter)) == _bmWordSize,
91 "size inconsistency");
92 return _bmStartWord == (HeapWord*)(heap_rs.start()) &&
93 _bmWordSize == heap_rs.word_size();
94 }
95 #endif
96
97 void G1CMBitMapRO::print_on_error(outputStream* st, const char* prefix) const {
98 _bm.print_on_error(st, prefix);
99 }
100
101 size_t G1CMBitMap::compute_size(size_t heap_size) {
102 return ReservedSpace::allocation_align_size_up(heap_size / mark_distance());
103 }
104
105 size_t G1CMBitMap::mark_distance() {
106 return MinObjAlignmentInBytes * BitsPerByte;
107 }
108
109 void G1CMBitMap::initialize(MemRegion heap, G1RegionToSpaceMapper* storage) {
110 _bmStartWord = heap.start();
111 _bmWordSize = heap.word_size();
112
113 _bm = BitMapView((BitMap::bm_word_t*) storage->reserved().start(), _bmWordSize >> _shifter);
114
115 storage->set_mapping_changed_listener(&_listener);
116 }
117
118 void G1CMBitMapMappingChangedListener::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->clear_range(mr);
125 }
126
127 void G1CMBitMap::clear_range(MemRegion mr) {
128 mr.intersection(MemRegion(_bmStartWord, _bmWordSize));
129 assert(!mr.is_empty(), "unexpected empty region");
130 // convert address range into offset range
131 _bm.at_put_range(heapWordToOffset(mr.start()),
132 heapWordToOffset(mr.end()), false);
133 }
134
135 G1CMMarkStack::G1CMMarkStack() :
136 _reserved_space(),
137 _base(NULL),
138 _capacity(0),
139 _saved_index((size_t)AllBits),
140 _should_expand(false) {
141 set_empty();
142 }
143
144 bool G1CMMarkStack::resize(size_t new_capacity) {
145 assert(is_empty(), "Only resize when stack is empty.");
146 assert(new_capacity <= MarkStackSizeMax,
147 "Trying to resize stack to " SIZE_FORMAT " elements when the maximum is " SIZE_FORMAT, new_capacity, MarkStackSizeMax);
148
149 size_t reservation_size = ReservedSpace::allocation_align_size_up(new_capacity * sizeof(oop));
150
151 ReservedSpace rs(reservation_size);
152 if (!rs.is_reserved()) {
153 log_warning(gc)("Failed to reserve memory for new overflow mark stack with " SIZE_FORMAT " elements and size " SIZE_FORMAT "B.", new_capacity, reservation_size);
154 return false;
155 }
156
157 VirtualSpace vs;
158
159 if (!vs.initialize(rs, rs.size())) {
160 rs.release();
161 log_warning(gc)("Failed to commit memory for new overflow mark stack of size " SIZE_FORMAT "B.", rs.size());
162 return false;
163 }
164
165 assert(vs.committed_size() == rs.size(), "Failed to commit all of the mark stack.");
166
167 // Release old mapping.
168 _reserved_space.release();
169
170 // Save new mapping for future unmapping.
171 _reserved_space = rs;
172
173 MemTracker::record_virtual_memory_type((address)_reserved_space.base(), mtGC);
174
175 _base = (oop*) vs.low();
176 _capacity = new_capacity;
177 set_empty();
178 _should_expand = false;
179
180 return true;
181 }
182
183 bool G1CMMarkStack::allocate(size_t capacity) {
184 return resize(capacity);
185 }
186
187 void G1CMMarkStack::expand() {
188 // Clear expansion flag
189 _should_expand = false;
190
191 if (_capacity == MarkStackSizeMax) {
192 log_debug(gc)("Can not expand overflow mark stack further, already at maximum capacity of " SIZE_FORMAT " elements.", _capacity);
193 return;
194 }
195 size_t old_capacity = _capacity;
196 // Double capacity if possible
197 size_t new_capacity = MIN2(old_capacity * 2, MarkStackSizeMax);
198
199 if (resize(new_capacity)) {
200 log_debug(gc)("Expanded marking stack capacity from " SIZE_FORMAT " to " SIZE_FORMAT " elements",
201 old_capacity, new_capacity);
202 } else {
203 log_warning(gc)("Failed to expand marking stack capacity from " SIZE_FORMAT " to " SIZE_FORMAT " elements",
204 old_capacity, new_capacity);
205 }
206 }
207
208 G1CMMarkStack::~G1CMMarkStack() {
209 if (_base != NULL) {
210 _base = NULL;
211 _reserved_space.release();
212 }
213 }
214
215 void G1CMMarkStack::par_push_arr(oop* buffer, size_t n) {
216 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
217 size_t start = _index;
218 size_t next_index = start + n;
219 if (next_index > _capacity) {
220 _overflow = true;
221 return;
222 }
223 // Otherwise.
224 _index = next_index;
225 for (size_t i = 0; i < n; i++) {
226 size_t ind = start + i;
227 assert(ind < _capacity, "By overflow test above.");
228 _base[ind] = buffer[i];
229 }
230 }
231
232 bool G1CMMarkStack::par_pop_arr(oop* buffer, size_t max, size_t* n) {
233 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
234 size_t index = _index;
235 if (index == 0) {
236 *n = 0;
237 return false;
238 } else {
239 size_t k = MIN2(max, index);
240 size_t new_ind = index - k;
241 for (size_t j = 0; j < k; j++) {
242 buffer[j] = _base[new_ind + j];
243 }
244 _index = new_ind;
245 *n = k;
246 return true;
247 }
248 }
249
250 void G1CMMarkStack::note_start_of_gc() {
251 assert(_saved_index == (size_t)AllBits, "note_start_of_gc()/end_of_gc() calls bracketed incorrectly");
252 _saved_index = _index;
253 }
254
255 void G1CMMarkStack::note_end_of_gc() {
256 guarantee(!stack_modified(), "Saved index " SIZE_FORMAT " must be the same as " SIZE_FORMAT, _saved_index, _index);
257
258 _saved_index = (size_t)AllBits;
259 }
260
261 G1CMRootRegions::G1CMRootRegions() :
262 _cm(NULL), _scan_in_progress(false),
263 _should_abort(false), _claimed_survivor_index(0) { }
264
265 void G1CMRootRegions::init(const G1SurvivorRegions* survivors, G1ConcurrentMark* cm) {
266 _survivors = survivors;
267 _cm = cm;
268 }
269
270 void G1CMRootRegions::prepare_for_scan() {
271 assert(!scan_in_progress(), "pre-condition");
272
273 // Currently, only survivors can be root regions.
274 _claimed_survivor_index = 0;
275 _scan_in_progress = _survivors->regions()->is_nonempty();
276 _should_abort = false;
277 }
278
279 HeapRegion* G1CMRootRegions::claim_next() {
280 if (_should_abort) {
281 // If someone has set the should_abort flag, we return NULL to
282 // force the caller to bail out of their loop.
283 return NULL;
284 }
285
286 // Currently, only survivors can be root regions.
287 const GrowableArray<HeapRegion*>* survivor_regions = _survivors->regions();
288
289 int claimed_index = Atomic::add(1, &_claimed_survivor_index) - 1;
290 if (claimed_index < survivor_regions->length()) {
291 return survivor_regions->at(claimed_index);
292 }
293 return NULL;
294 }
295
296 uint G1CMRootRegions::num_root_regions() const {
297 return (uint)_survivors->regions()->length();
298 }
299
300 void G1CMRootRegions::notify_scan_done() {
301 MutexLockerEx x(RootRegionScan_lock, Mutex::_no_safepoint_check_flag);
302 _scan_in_progress = false;
303 RootRegionScan_lock->notify_all();
304 }
305
306 void G1CMRootRegions::cancel_scan() {
307 notify_scan_done();
308 }
309
310 void G1CMRootRegions::scan_finished() {
311 assert(scan_in_progress(), "pre-condition");
312
313 // Currently, only survivors can be root regions.
314 if (!_should_abort) {
315 assert(_claimed_survivor_index >= 0, "otherwise comparison is invalid: %d", _claimed_survivor_index);
316 assert((uint)_claimed_survivor_index >= _survivors->length(),
317 "we should have claimed all survivors, claimed index = %u, length = %u",
318 (uint)_claimed_survivor_index, _survivors->length());
319 }
320
321 notify_scan_done();
322 }
323
324 bool G1CMRootRegions::wait_until_scan_finished() {
325 if (!scan_in_progress()) return false;
326
327 {
328 MutexLockerEx x(RootRegionScan_lock, Mutex::_no_safepoint_check_flag);
329 while (scan_in_progress()) {
330 RootRegionScan_lock->wait(Mutex::_no_safepoint_check_flag);
331 }
332 }
333 return true;
334 }
335
336 uint G1ConcurrentMark::scale_parallel_threads(uint n_par_threads) {
337 return MAX2((n_par_threads + 2) / 4, 1U);
338 }
339
340 G1ConcurrentMark::G1ConcurrentMark(G1CollectedHeap* g1h, G1RegionToSpaceMapper* prev_bitmap_storage, G1RegionToSpaceMapper* next_bitmap_storage) :
341 _g1h(g1h),
342 _markBitMap1(),
343 _markBitMap2(),
344 _parallel_marking_threads(0),
345 _max_parallel_marking_threads(0),
346 _sleep_factor(0.0),
347 _marking_task_overhead(1.0),
348 _cleanup_list("Cleanup List"),
349
350 _prevMarkBitMap(&_markBitMap1),
351 _nextMarkBitMap(&_markBitMap2),
352
353 _global_mark_stack(),
354 // _finger set in set_non_marking_state
355
356 _max_worker_id(ParallelGCThreads),
357 // _active_tasks set in set_non_marking_state
358 // _tasks set inside the constructor
359 _task_queues(new G1CMTaskQueueSet((int) _max_worker_id)),
360 _terminator(ParallelTaskTerminator((int) _max_worker_id, _task_queues)),
361
362 _has_overflown(false),
363 _concurrent(false),
364 _has_aborted(false),
365 _restart_for_overflow(false),
366 _concurrent_marking_in_progress(false),
367 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
368 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()),
369
370 // _verbose_level set below
371
372 _init_times(),
373 _remark_times(), _remark_mark_times(), _remark_weak_ref_times(),
374 _cleanup_times(),
375 _total_counting_time(0.0),
376 _total_rs_scrub_time(0.0),
377
378 _parallel_workers(NULL),
379
380 _completed_initialization(false) {
381
382 _markBitMap1.initialize(g1h->reserved_region(), prev_bitmap_storage);
383 _markBitMap2.initialize(g1h->reserved_region(), next_bitmap_storage);
384
385 // Create & start a ConcurrentMark thread.
386 _cmThread = new ConcurrentMarkThread(this);
387 assert(cmThread() != NULL, "CM Thread should have been created");
388 assert(cmThread()->cm() != NULL, "CM Thread should refer to this cm");
389 if (_cmThread->osthread() == NULL) {
390 vm_shutdown_during_initialization("Could not create ConcurrentMarkThread");
391 }
392
393 assert(CGC_lock != NULL, "Where's the CGC_lock?");
394 assert(_markBitMap1.covers(g1h->reserved_region()), "_markBitMap1 inconsistency");
395 assert(_markBitMap2.covers(g1h->reserved_region()), "_markBitMap2 inconsistency");
396
397 SATBMarkQueueSet& satb_qs = JavaThread::satb_mark_queue_set();
398 satb_qs.set_buffer_size(G1SATBBufferSize);
399
400 _root_regions.init(_g1h->survivor(), this);
401
402 if (ConcGCThreads > ParallelGCThreads) {
403 log_warning(gc)("Can't have more ConcGCThreads (%u) than ParallelGCThreads (%u).",
404 ConcGCThreads, ParallelGCThreads);
405 return;
406 }
407 if (!FLAG_IS_DEFAULT(ConcGCThreads) && ConcGCThreads > 0) {
408 // Note: ConcGCThreads has precedence over G1MarkingOverheadPercent
409 // if both are set
410 _sleep_factor = 0.0;
411 _marking_task_overhead = 1.0;
412 } else if (G1MarkingOverheadPercent > 0) {
413 // We will calculate the number of parallel marking threads based
414 // on a target overhead with respect to the soft real-time goal
415 double marking_overhead = (double) G1MarkingOverheadPercent / 100.0;
416 double overall_cm_overhead =
417 (double) MaxGCPauseMillis * marking_overhead /
418 (double) GCPauseIntervalMillis;
419 double cpu_ratio = 1.0 / os::initial_active_processor_count();
420 double marking_thread_num = ceil(overall_cm_overhead / cpu_ratio);
421 double marking_task_overhead =
422 overall_cm_overhead / marking_thread_num * os::initial_active_processor_count();
423 double sleep_factor =
424 (1.0 - marking_task_overhead) / marking_task_overhead;
425
426 FLAG_SET_ERGO(uint, ConcGCThreads, (uint) marking_thread_num);
427 _sleep_factor = sleep_factor;
428 _marking_task_overhead = marking_task_overhead;
429 } else {
430 // Calculate the number of parallel marking threads by scaling
431 // the number of parallel GC threads.
432 uint marking_thread_num = scale_parallel_threads(ParallelGCThreads);
433 FLAG_SET_ERGO(uint, ConcGCThreads, marking_thread_num);
434 _sleep_factor = 0.0;
435 _marking_task_overhead = 1.0;
436 }
437
438 assert(ConcGCThreads > 0, "Should have been set");
439 log_debug(gc)("ConcGCThreads: %u", ConcGCThreads);
440 log_debug(gc)("ParallelGCThreads: %u", ParallelGCThreads);
441 _parallel_marking_threads = ConcGCThreads;
442 _max_parallel_marking_threads = _parallel_marking_threads;
443
444 _parallel_workers = new WorkGang("G1 Marker",
445 _max_parallel_marking_threads, false, true);
446 if (_parallel_workers == NULL) {
447 vm_exit_during_initialization("Failed necessary allocation.");
448 } else {
449 _parallel_workers->initialize_workers();
450 }
451
452 if (FLAG_IS_DEFAULT(MarkStackSize)) {
453 size_t mark_stack_size =
454 MIN2(MarkStackSizeMax,
455 MAX2(MarkStackSize, (size_t) (parallel_marking_threads() * TASKQUEUE_SIZE)));
456 // Verify that the calculated value for MarkStackSize is in range.
457 // It would be nice to use the private utility routine from Arguments.
458 if (!(mark_stack_size >= 1 && mark_stack_size <= MarkStackSizeMax)) {
459 log_warning(gc)("Invalid value calculated for MarkStackSize (" SIZE_FORMAT "): "
460 "must be between 1 and " SIZE_FORMAT,
461 mark_stack_size, MarkStackSizeMax);
462 return;
463 }
464 FLAG_SET_ERGO(size_t, MarkStackSize, mark_stack_size);
465 } else {
466 // Verify MarkStackSize is in range.
467 if (FLAG_IS_CMDLINE(MarkStackSize)) {
468 if (FLAG_IS_DEFAULT(MarkStackSizeMax)) {
469 if (!(MarkStackSize >= 1 && MarkStackSize <= MarkStackSizeMax)) {
470 log_warning(gc)("Invalid value specified for MarkStackSize (" SIZE_FORMAT "): "
471 "must be between 1 and " SIZE_FORMAT,
472 MarkStackSize, MarkStackSizeMax);
473 return;
474 }
475 } else if (FLAG_IS_CMDLINE(MarkStackSizeMax)) {
476 if (!(MarkStackSize >= 1 && MarkStackSize <= MarkStackSizeMax)) {
477 log_warning(gc)("Invalid value specified for MarkStackSize (" SIZE_FORMAT ")"
478 " or for MarkStackSizeMax (" SIZE_FORMAT ")",
479 MarkStackSize, MarkStackSizeMax);
480 return;
481 }
482 }
483 }
484 }
485
486 if (!_global_mark_stack.allocate(MarkStackSize)) {
487 vm_exit_during_initialization("Failed to allocate initial concurrent mark overflow mark stack.");
488 return;
489 }
490
491 _tasks = NEW_C_HEAP_ARRAY(G1CMTask*, _max_worker_id, mtGC);
492 _accum_task_vtime = NEW_C_HEAP_ARRAY(double, _max_worker_id, mtGC);
493
494 // so that the assertion in MarkingTaskQueue::task_queue doesn't fail
495 _active_tasks = _max_worker_id;
496
497 for (uint i = 0; i < _max_worker_id; ++i) {
498 G1CMTaskQueue* task_queue = new G1CMTaskQueue();
499 task_queue->initialize();
500 _task_queues->register_queue(i, task_queue);
501
502 _tasks[i] = new G1CMTask(i, this, task_queue, _task_queues);
503
504 _accum_task_vtime[i] = 0.0;
505 }
506
507 // so that the call below can read a sensible value
508 _heap_start = g1h->reserved_region().start();
509 set_non_marking_state();
510 _completed_initialization = true;
511 }
512
513 void G1ConcurrentMark::reset() {
514 // Starting values for these two. This should be called in a STW
515 // phase.
516 MemRegion reserved = _g1h->g1_reserved();
517 _heap_start = reserved.start();
518 _heap_end = reserved.end();
519
520 // Separated the asserts so that we know which one fires.
521 assert(_heap_start != NULL, "heap bounds should look ok");
522 assert(_heap_end != NULL, "heap bounds should look ok");
523 assert(_heap_start < _heap_end, "heap bounds should look ok");
524
525 // Reset all the marking data structures and any necessary flags
526 reset_marking_state();
527
528 // We do reset all of them, since different phases will use
529 // different number of active threads. So, it's easiest to have all
530 // of them ready.
531 for (uint i = 0; i < _max_worker_id; ++i) {
532 _tasks[i]->reset(_nextMarkBitMap);
533 }
534
535 // we need this to make sure that the flag is on during the evac
536 // pause with initial mark piggy-backed
537 set_concurrent_marking_in_progress();
538 }
539
540
541 void G1ConcurrentMark::reset_marking_state(bool clear_overflow) {
542 _global_mark_stack.set_should_expand(has_overflown());
543 _global_mark_stack.set_empty(); // Also clears the overflow stack's overflow flag
544 if (clear_overflow) {
545 clear_has_overflown();
546 } else {
547 assert(has_overflown(), "pre-condition");
548 }
549 _finger = _heap_start;
550
551 for (uint i = 0; i < _max_worker_id; ++i) {
552 G1CMTaskQueue* queue = _task_queues->queue(i);
553 queue->set_empty();
554 }
555 }
556
557 void G1ConcurrentMark::set_concurrency(uint active_tasks) {
558 assert(active_tasks <= _max_worker_id, "we should not have more");
559
560 _active_tasks = active_tasks;
561 // Need to update the three data structures below according to the
562 // number of active threads for this phase.
563 _terminator = ParallelTaskTerminator((int) active_tasks, _task_queues);
564 _first_overflow_barrier_sync.set_n_workers((int) active_tasks);
565 _second_overflow_barrier_sync.set_n_workers((int) active_tasks);
566 }
567
568 void G1ConcurrentMark::set_concurrency_and_phase(uint active_tasks, bool concurrent) {
569 set_concurrency(active_tasks);
570
571 _concurrent = concurrent;
572 // We propagate this to all tasks, not just the active ones.
573 for (uint i = 0; i < _max_worker_id; ++i)
574 _tasks[i]->set_concurrent(concurrent);
575
576 if (concurrent) {
577 set_concurrent_marking_in_progress();
578 } else {
579 // We currently assume that the concurrent flag has been set to
580 // false before we start remark. At this point we should also be
581 // in a STW phase.
582 assert(!concurrent_marking_in_progress(), "invariant");
583 assert(out_of_regions(),
584 "only way to get here: _finger: " PTR_FORMAT ", _heap_end: " PTR_FORMAT,
585 p2i(_finger), p2i(_heap_end));
586 }
587 }
588
589 void G1ConcurrentMark::set_non_marking_state() {
590 // We set the global marking state to some default values when we're
591 // not doing marking.
592 reset_marking_state();
593 _active_tasks = 0;
594 clear_concurrent_marking_in_progress();
595 }
596
597 G1ConcurrentMark::~G1ConcurrentMark() {
598 // The G1ConcurrentMark instance is never freed.
599 ShouldNotReachHere();
600 }
601
602 class G1ClearBitMapTask : public AbstractGangTask {
603 public:
604 static size_t chunk_size() { return M; }
605
606 private:
607 // Heap region closure used for clearing the given mark bitmap.
608 class G1ClearBitmapHRClosure : public HeapRegionClosure {
609 private:
610 G1CMBitMap* _bitmap;
611 G1ConcurrentMark* _cm;
612 public:
613 G1ClearBitmapHRClosure(G1CMBitMap* bitmap, G1ConcurrentMark* cm) : HeapRegionClosure(), _cm(cm), _bitmap(bitmap) {
614 }
615
616 virtual bool doHeapRegion(HeapRegion* r) {
617 size_t const chunk_size_in_words = G1ClearBitMapTask::chunk_size() / HeapWordSize;
618
619 HeapWord* cur = r->bottom();
620 HeapWord* const end = r->end();
621
622 while (cur < end) {
623 MemRegion mr(cur, MIN2(cur + chunk_size_in_words, end));
624 _bitmap->clear_range(mr);
625
626 cur += chunk_size_in_words;
627
628 // Abort iteration if after yielding the marking has been aborted.
629 if (_cm != NULL && _cm->do_yield_check() && _cm->has_aborted()) {
630 return true;
631 }
632 // Repeat the asserts from before the start of the closure. We will do them
633 // as asserts here to minimize their overhead on the product. However, we
634 // will have them as guarantees at the beginning / end of the bitmap
635 // clearing to get some checking in the product.
636 assert(_cm == NULL || _cm->cmThread()->during_cycle(), "invariant");
637 assert(_cm == NULL || !G1CollectedHeap::heap()->collector_state()->mark_in_progress(), "invariant");
638 }
639 assert(cur == end, "Must have completed iteration over the bitmap for region %u.", r->hrm_index());
640
641 return false;
642 }
643 };
644
645 G1ClearBitmapHRClosure _cl;
646 HeapRegionClaimer _hr_claimer;
647 bool _suspendible; // If the task is suspendible, workers must join the STS.
648
649 public:
650 G1ClearBitMapTask(G1CMBitMap* bitmap, G1ConcurrentMark* cm, uint n_workers, bool suspendible) :
651 AbstractGangTask("G1 Clear Bitmap"),
652 _cl(bitmap, suspendible ? cm : NULL),
653 _hr_claimer(n_workers),
654 _suspendible(suspendible)
655 { }
656
657 void work(uint worker_id) {
658 SuspendibleThreadSetJoiner sts_join(_suspendible);
659 G1CollectedHeap::heap()->heap_region_par_iterate(&_cl, worker_id, &_hr_claimer, true);
660 }
661
662 bool is_complete() {
663 return _cl.complete();
664 }
665 };
666
667 void G1ConcurrentMark::clear_bitmap(G1CMBitMap* bitmap, WorkGang* workers, bool may_yield) {
668 assert(may_yield || SafepointSynchronize::is_at_safepoint(), "Non-yielding bitmap clear only allowed at safepoint.");
669
670 size_t const num_bytes_to_clear = (HeapRegion::GrainBytes * _g1h->num_regions()) / G1CMBitMap::heap_map_factor();
671 size_t const num_chunks = align_size_up(num_bytes_to_clear, G1ClearBitMapTask::chunk_size()) / G1ClearBitMapTask::chunk_size();
672
673 uint const num_workers = (uint)MIN2(num_chunks, (size_t)workers->active_workers());
674
675 G1ClearBitMapTask cl(bitmap, this, num_workers, may_yield);
676
677 log_debug(gc, ergo)("Running %s with %u workers for " SIZE_FORMAT " work units.", cl.name(), num_workers, num_chunks);
678 workers->run_task(&cl, num_workers);
679 guarantee(!may_yield || cl.is_complete(), "Must have completed iteration when not yielding.");
680 }
681
682 void G1ConcurrentMark::cleanup_for_next_mark() {
683 // Make sure that the concurrent mark thread looks to still be in
684 // the current cycle.
685 guarantee(cmThread()->during_cycle(), "invariant");
686
687 // We are finishing up the current cycle by clearing the next
688 // marking bitmap and getting it ready for the next cycle. During
689 // this time no other cycle can start. So, let's make sure that this
690 // is the case.
691 guarantee(!_g1h->collector_state()->mark_in_progress(), "invariant");
692
693 clear_bitmap(_nextMarkBitMap, _parallel_workers, true);
694
695 // Clear the live count data. If the marking has been aborted, the abort()
696 // call already did that.
697 if (!has_aborted()) {
698 clear_live_data(_parallel_workers);
699 DEBUG_ONLY(verify_live_data_clear());
700 }
701
702 // Repeat the asserts from above.
703 guarantee(cmThread()->during_cycle(), "invariant");
704 guarantee(!_g1h->collector_state()->mark_in_progress(), "invariant");
705 }
706
707 void G1ConcurrentMark::clear_prev_bitmap(WorkGang* workers) {
708 assert(SafepointSynchronize::is_at_safepoint(), "Should only clear the entire prev bitmap at a safepoint.");
709 clear_bitmap((G1CMBitMap*)_prevMarkBitMap, workers, false);
710 }
711
712 class CheckBitmapClearHRClosure : public HeapRegionClosure {
713 G1CMBitMap* _bitmap;
714 bool _error;
715 public:
716 CheckBitmapClearHRClosure(G1CMBitMap* bitmap) : _bitmap(bitmap) {
717 }
718
719 virtual bool doHeapRegion(HeapRegion* r) {
720 // This closure can be called concurrently to the mutator, so we must make sure
721 // that the result of the getNextMarkedWordAddress() call is compared to the
722 // value passed to it as limit to detect any found bits.
723 // end never changes in G1.
724 HeapWord* end = r->end();
725 return _bitmap->getNextMarkedWordAddress(r->bottom(), end) != end;
726 }
727 };
728
729 bool G1ConcurrentMark::nextMarkBitmapIsClear() {
730 CheckBitmapClearHRClosure cl(_nextMarkBitMap);
731 _g1h->heap_region_iterate(&cl);
732 return cl.complete();
733 }
734
735 class NoteStartOfMarkHRClosure: public HeapRegionClosure {
736 public:
737 bool doHeapRegion(HeapRegion* r) {
738 r->note_start_of_marking();
739 return false;
740 }
741 };
742
743 void G1ConcurrentMark::checkpointRootsInitialPre() {
744 G1CollectedHeap* g1h = G1CollectedHeap::heap();
745 G1Policy* g1p = g1h->g1_policy();
746
747 _has_aborted = false;
748
749 // Initialize marking structures. This has to be done in a STW phase.
750 reset();
751
752 // For each region note start of marking.
753 NoteStartOfMarkHRClosure startcl;
754 g1h->heap_region_iterate(&startcl);
755 }
756
757
758 void G1ConcurrentMark::checkpointRootsInitialPost() {
759 G1CollectedHeap* g1h = G1CollectedHeap::heap();
760
761 // Start Concurrent Marking weak-reference discovery.
762 ReferenceProcessor* rp = g1h->ref_processor_cm();
763 // enable ("weak") refs discovery
764 rp->enable_discovery();
765 rp->setup_policy(false); // snapshot the soft ref policy to be used in this cycle
766
767 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
768 // This is the start of the marking cycle, we're expected all
769 // threads to have SATB queues with active set to false.
770 satb_mq_set.set_active_all_threads(true, /* new active value */
771 false /* expected_active */);
772
773 _root_regions.prepare_for_scan();
774
775 // update_g1_committed() will be called at the end of an evac pause
776 // when marking is on. So, it's also called at the end of the
777 // initial-mark pause to update the heap end, if the heap expands
778 // during it. No need to call it here.
779 }
780
781 /*
782 * Notice that in the next two methods, we actually leave the STS
783 * during the barrier sync and join it immediately afterwards. If we
784 * do not do this, the following deadlock can occur: one thread could
785 * be in the barrier sync code, waiting for the other thread to also
786 * sync up, whereas another one could be trying to yield, while also
787 * waiting for the other threads to sync up too.
788 *
789 * Note, however, that this code is also used during remark and in
790 * this case we should not attempt to leave / enter the STS, otherwise
791 * we'll either hit an assert (debug / fastdebug) or deadlock
792 * (product). So we should only leave / enter the STS if we are
793 * operating concurrently.
794 *
795 * Because the thread that does the sync barrier has left the STS, it
796 * is possible to be suspended for a Full GC or an evacuation pause
797 * could occur. This is actually safe, since the entering the sync
798 * barrier is one of the last things do_marking_step() does, and it
799 * doesn't manipulate any data structures afterwards.
800 */
801
802 void G1ConcurrentMark::enter_first_sync_barrier(uint worker_id) {
803 bool barrier_aborted;
804 {
805 SuspendibleThreadSetLeaver sts_leave(concurrent());
806 barrier_aborted = !_first_overflow_barrier_sync.enter();
807 }
808
809 // at this point everyone should have synced up and not be doing any
810 // more work
811
812 if (barrier_aborted) {
813 // If the barrier aborted we ignore the overflow condition and
814 // just abort the whole marking phase as quickly as possible.
815 return;
816 }
817
818 // If we're executing the concurrent phase of marking, reset the marking
819 // state; otherwise the marking state is reset after reference processing,
820 // during the remark pause.
821 // If we reset here as a result of an overflow during the remark we will
822 // see assertion failures from any subsequent set_concurrency_and_phase()
823 // calls.
824 if (concurrent()) {
825 // let the task associated with with worker 0 do this
826 if (worker_id == 0) {
827 // task 0 is responsible for clearing the global data structures
828 // We should be here because of an overflow. During STW we should
829 // not clear the overflow flag since we rely on it being true when
830 // we exit this method to abort the pause and restart concurrent
831 // marking.
832 reset_marking_state(true /* clear_overflow */);
833
834 log_info(gc, marking)("Concurrent Mark reset for overflow");
835 }
836 }
837
838 // after this, each task should reset its own data structures then
839 // then go into the second barrier
840 }
841
842 void G1ConcurrentMark::enter_second_sync_barrier(uint worker_id) {
843 SuspendibleThreadSetLeaver sts_leave(concurrent());
844 _second_overflow_barrier_sync.enter();
845
846 // at this point everything should be re-initialized and ready to go
847 }
848
849 class G1CMConcurrentMarkingTask: public AbstractGangTask {
850 private:
851 G1ConcurrentMark* _cm;
852 ConcurrentMarkThread* _cmt;
853
854 public:
855 void work(uint worker_id) {
856 assert(Thread::current()->is_ConcurrentGC_thread(),
857 "this should only be done by a conc GC thread");
858 ResourceMark rm;
859
860 double start_vtime = os::elapsedVTime();
861
862 {
863 SuspendibleThreadSetJoiner sts_join;
864
865 assert(worker_id < _cm->active_tasks(), "invariant");
866 G1CMTask* the_task = _cm->task(worker_id);
867 the_task->record_start_time();
868 if (!_cm->has_aborted()) {
869 do {
870 double start_vtime_sec = os::elapsedVTime();
871 double mark_step_duration_ms = G1ConcMarkStepDurationMillis;
872
873 the_task->do_marking_step(mark_step_duration_ms,
874 true /* do_termination */,
875 false /* is_serial*/);
876
877 double end_vtime_sec = os::elapsedVTime();
878 double elapsed_vtime_sec = end_vtime_sec - start_vtime_sec;
879 _cm->clear_has_overflown();
880
881 _cm->do_yield_check();
882
883 jlong sleep_time_ms;
884 if (!_cm->has_aborted() && the_task->has_aborted()) {
885 sleep_time_ms =
886 (jlong) (elapsed_vtime_sec * _cm->sleep_factor() * 1000.0);
887 {
888 SuspendibleThreadSetLeaver sts_leave;
889 os::sleep(Thread::current(), sleep_time_ms, false);
890 }
891 }
892 } while (!_cm->has_aborted() && the_task->has_aborted());
893 }
894 the_task->record_end_time();
895 guarantee(!the_task->has_aborted() || _cm->has_aborted(), "invariant");
896 }
897
898 double end_vtime = os::elapsedVTime();
899 _cm->update_accum_task_vtime(worker_id, end_vtime - start_vtime);
900 }
901
902 G1CMConcurrentMarkingTask(G1ConcurrentMark* cm,
903 ConcurrentMarkThread* cmt) :
904 AbstractGangTask("Concurrent Mark"), _cm(cm), _cmt(cmt) { }
905
906 ~G1CMConcurrentMarkingTask() { }
907 };
908
909 // Calculates the number of active workers for a concurrent
910 // phase.
911 uint G1ConcurrentMark::calc_parallel_marking_threads() {
912 uint n_conc_workers = 0;
913 if (!UseDynamicNumberOfGCThreads ||
914 (!FLAG_IS_DEFAULT(ConcGCThreads) &&
915 !ForceDynamicNumberOfGCThreads)) {
916 n_conc_workers = max_parallel_marking_threads();
917 } else {
918 n_conc_workers =
919 AdaptiveSizePolicy::calc_default_active_workers(max_parallel_marking_threads(),
920 1, /* Minimum workers */
921 parallel_marking_threads(),
922 Threads::number_of_non_daemon_threads());
923 // Don't scale down "n_conc_workers" by scale_parallel_threads() because
924 // that scaling has already gone into "_max_parallel_marking_threads".
925 }
926 assert(n_conc_workers > 0 && n_conc_workers <= max_parallel_marking_threads(),
927 "Calculated number of workers must be larger than zero and at most the maximum %u, but is %u",
928 max_parallel_marking_threads(), n_conc_workers);
929 return n_conc_workers;
930 }
931
932 void G1ConcurrentMark::scanRootRegion(HeapRegion* hr) {
933 // Currently, only survivors can be root regions.
934 assert(hr->next_top_at_mark_start() == hr->bottom(), "invariant");
935 G1RootRegionScanClosure cl(_g1h, this);
936
937 const uintx interval = PrefetchScanIntervalInBytes;
938 HeapWord* curr = hr->bottom();
939 const HeapWord* end = hr->top();
940 while (curr < end) {
941 Prefetch::read(curr, interval);
942 oop obj = oop(curr);
943 int size = obj->oop_iterate_size(&cl);
944 assert(size == obj->size(), "sanity");
945 curr += size;
946 }
947 }
948
949 class G1CMRootRegionScanTask : public AbstractGangTask {
950 private:
951 G1ConcurrentMark* _cm;
952
953 public:
954 G1CMRootRegionScanTask(G1ConcurrentMark* cm) :
955 AbstractGangTask("G1 Root Region Scan"), _cm(cm) { }
956
957 void work(uint worker_id) {
958 assert(Thread::current()->is_ConcurrentGC_thread(),
959 "this should only be done by a conc GC thread");
960
961 G1CMRootRegions* root_regions = _cm->root_regions();
962 HeapRegion* hr = root_regions->claim_next();
963 while (hr != NULL) {
964 _cm->scanRootRegion(hr);
965 hr = root_regions->claim_next();
966 }
967 }
968 };
969
970 void G1ConcurrentMark::scan_root_regions() {
971 // scan_in_progress() will have been set to true only if there was
972 // at least one root region to scan. So, if it's false, we
973 // should not attempt to do any further work.
974 if (root_regions()->scan_in_progress()) {
975 assert(!has_aborted(), "Aborting before root region scanning is finished not supported.");
976
977 _parallel_marking_threads = MIN2(calc_parallel_marking_threads(),
978 // We distribute work on a per-region basis, so starting
979 // more threads than that is useless.
980 root_regions()->num_root_regions());
981 assert(parallel_marking_threads() <= max_parallel_marking_threads(),
982 "Maximum number of marking threads exceeded");
983
984 G1CMRootRegionScanTask task(this);
985 log_debug(gc, ergo)("Running %s using %u workers for %u work units.",
986 task.name(), _parallel_marking_threads, root_regions()->num_root_regions());
987 _parallel_workers->run_task(&task, _parallel_marking_threads);
988
989 // It's possible that has_aborted() is true here without actually
990 // aborting the survivor scan earlier. This is OK as it's
991 // mainly used for sanity checking.
992 root_regions()->scan_finished();
993 }
994 }
995
996 void G1ConcurrentMark::concurrent_cycle_start() {
997 _gc_timer_cm->register_gc_start();
998
999 _gc_tracer_cm->report_gc_start(GCCause::_no_gc /* first parameter is not used */, _gc_timer_cm->gc_start());
1000
1001 _g1h->trace_heap_before_gc(_gc_tracer_cm);
1002 }
1003
1004 void G1ConcurrentMark::concurrent_cycle_end() {
1005 _g1h->trace_heap_after_gc(_gc_tracer_cm);
1006
1007 if (has_aborted()) {
1008 _gc_tracer_cm->report_concurrent_mode_failure();
1009 }
1010
1011 _gc_timer_cm->register_gc_end();
1012
1013 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
1014 }
1015
1016 void G1ConcurrentMark::mark_from_roots() {
1017 // we might be tempted to assert that:
1018 // assert(asynch == !SafepointSynchronize::is_at_safepoint(),
1019 // "inconsistent argument?");
1020 // However that wouldn't be right, because it's possible that
1021 // a safepoint is indeed in progress as a younger generation
1022 // stop-the-world GC happens even as we mark in this generation.
1023
1024 _restart_for_overflow = false;
1025
1026 // _g1h has _n_par_threads
1027 _parallel_marking_threads = calc_parallel_marking_threads();
1028 assert(parallel_marking_threads() <= max_parallel_marking_threads(),
1029 "Maximum number of marking threads exceeded");
1030
1031 uint active_workers = MAX2(1U, parallel_marking_threads());
1032 assert(active_workers > 0, "Should have been set");
1033
1034 // Setting active workers is not guaranteed since fewer
1035 // worker threads may currently exist and more may not be
1036 // available.
1037 active_workers = _parallel_workers->update_active_workers(active_workers);
1038 // Parallel task terminator is set in "set_concurrency_and_phase()"
1039 set_concurrency_and_phase(active_workers, true /* concurrent */);
1040
1041 G1CMConcurrentMarkingTask markingTask(this, cmThread());
1042 _parallel_workers->run_task(&markingTask);
1043 print_stats();
1044 }
1045
1046 void G1ConcurrentMark::checkpointRootsFinal(bool clear_all_soft_refs) {
1047 // world is stopped at this checkpoint
1048 assert(SafepointSynchronize::is_at_safepoint(),
1049 "world should be stopped");
1050
1051 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1052
1053 // If a full collection has happened, we shouldn't do this.
1054 if (has_aborted()) {
1055 g1h->collector_state()->set_mark_in_progress(false); // So bitmap clearing isn't confused
1056 return;
1057 }
1058
1059 SvcGCMarker sgcm(SvcGCMarker::OTHER);
1060
1061 if (VerifyDuringGC) {
1062 HandleMark hm; // handle scope
1063 g1h->prepare_for_verify();
1064 Universe::verify(VerifyOption_G1UsePrevMarking, "During GC (before)");
1065 }
1066 g1h->verifier()->check_bitmaps("Remark Start");
1067
1068 G1Policy* g1p = g1h->g1_policy();
1069 g1p->record_concurrent_mark_remark_start();
1070
1071 double start = os::elapsedTime();
1072
1073 checkpointRootsFinalWork();
1074
1075 double mark_work_end = os::elapsedTime();
1076
1077 weakRefsWork(clear_all_soft_refs);
1078
1079 if (has_overflown()) {
1080 // We overflowed. Restart concurrent marking.
1081 _restart_for_overflow = true;
1082
1083 // Verify the heap w.r.t. the previous marking bitmap.
1084 if (VerifyDuringGC) {
1085 HandleMark hm; // handle scope
1086 g1h->prepare_for_verify();
1087 Universe::verify(VerifyOption_G1UsePrevMarking, "During GC (overflow)");
1088 }
1089
1090 // Clear the marking state because we will be restarting
1091 // marking due to overflowing the global mark stack.
1092 reset_marking_state();
1093 } else {
1094 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
1095 // We're done with marking.
1096 // This is the end of the marking cycle, we're expected all
1097 // threads to have SATB queues with active set to true.
1098 satb_mq_set.set_active_all_threads(false, /* new active value */
1099 true /* expected_active */);
1100
1101 if (VerifyDuringGC) {
1102 HandleMark hm; // handle scope
1103 g1h->prepare_for_verify();
1104 Universe::verify(VerifyOption_G1UseNextMarking, "During GC (after)");
1105 }
1106 g1h->verifier()->check_bitmaps("Remark End");
1107 assert(!restart_for_overflow(), "sanity");
1108 // Completely reset the marking state since marking completed
1109 set_non_marking_state();
1110 }
1111
1112 // Expand the marking stack, if we have to and if we can.
1113 if (_global_mark_stack.should_expand()) {
1114 _global_mark_stack.expand();
1115 }
1116
1117 // Statistics
1118 double now = os::elapsedTime();
1119 _remark_mark_times.add((mark_work_end - start) * 1000.0);
1120 _remark_weak_ref_times.add((now - mark_work_end) * 1000.0);
1121 _remark_times.add((now - start) * 1000.0);
1122
1123 g1p->record_concurrent_mark_remark_end();
1124
1125 G1CMIsAliveClosure is_alive(g1h);
1126 _gc_tracer_cm->report_object_count_after_gc(&is_alive);
1127 }
1128
1129 class G1NoteEndOfConcMarkClosure : public HeapRegionClosure {
1130 G1CollectedHeap* _g1;
1131 size_t _freed_bytes;
1132 FreeRegionList* _local_cleanup_list;
1133 uint _old_regions_removed;
1134 uint _humongous_regions_removed;
1135 HRRSCleanupTask* _hrrs_cleanup_task;
1136
1137 public:
1138 G1NoteEndOfConcMarkClosure(G1CollectedHeap* g1,
1139 FreeRegionList* local_cleanup_list,
1140 HRRSCleanupTask* hrrs_cleanup_task) :
1141 _g1(g1),
1142 _freed_bytes(0),
1143 _local_cleanup_list(local_cleanup_list),
1144 _old_regions_removed(0),
1145 _humongous_regions_removed(0),
1146 _hrrs_cleanup_task(hrrs_cleanup_task) { }
1147
1148 size_t freed_bytes() { return _freed_bytes; }
1149 const uint old_regions_removed() { return _old_regions_removed; }
1150 const uint humongous_regions_removed() { return _humongous_regions_removed; }
1151
1152 bool doHeapRegion(HeapRegion *hr) {
1153 if (hr->is_archive()) {
1154 return false;
1155 }
1156 _g1->reset_gc_time_stamps(hr);
1157 hr->note_end_of_marking();
1158
1159 if (hr->used() > 0 && hr->max_live_bytes() == 0 && !hr->is_young()) {
1160 _freed_bytes += hr->used();
1161 hr->set_containing_set(NULL);
1162 if (hr->is_humongous()) {
1163 _humongous_regions_removed++;
1164 _g1->free_humongous_region(hr, _local_cleanup_list, true /* skip_remset */);
1165 } else {
1166 _old_regions_removed++;
1167 _g1->free_region(hr, _local_cleanup_list, true /* skip_remset */);
1168 }
1169 } else {
1170 hr->rem_set()->do_cleanup_work(_hrrs_cleanup_task);
1171 }
1172
1173 return false;
1174 }
1175 };
1176
1177 class G1ParNoteEndTask: public AbstractGangTask {
1178 friend class G1NoteEndOfConcMarkClosure;
1179
1180 protected:
1181 G1CollectedHeap* _g1h;
1182 FreeRegionList* _cleanup_list;
1183 HeapRegionClaimer _hrclaimer;
1184
1185 public:
1186 G1ParNoteEndTask(G1CollectedHeap* g1h, FreeRegionList* cleanup_list, uint n_workers) :
1187 AbstractGangTask("G1 note end"), _g1h(g1h), _cleanup_list(cleanup_list), _hrclaimer(n_workers) {
1188 }
1189
1190 void work(uint worker_id) {
1191 FreeRegionList local_cleanup_list("Local Cleanup List");
1192 HRRSCleanupTask hrrs_cleanup_task;
1193 G1NoteEndOfConcMarkClosure g1_note_end(_g1h, &local_cleanup_list,
1194 &hrrs_cleanup_task);
1195 _g1h->heap_region_par_iterate(&g1_note_end, worker_id, &_hrclaimer);
1196 assert(g1_note_end.complete(), "Shouldn't have yielded!");
1197
1198 // Now update the lists
1199 _g1h->remove_from_old_sets(g1_note_end.old_regions_removed(), g1_note_end.humongous_regions_removed());
1200 {
1201 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
1202 _g1h->decrement_summary_bytes(g1_note_end.freed_bytes());
1203
1204 // If we iterate over the global cleanup list at the end of
1205 // cleanup to do this printing we will not guarantee to only
1206 // generate output for the newly-reclaimed regions (the list
1207 // might not be empty at the beginning of cleanup; we might
1208 // still be working on its previous contents). So we do the
1209 // printing here, before we append the new regions to the global
1210 // cleanup list.
1211
1212 G1HRPrinter* hr_printer = _g1h->hr_printer();
1213 if (hr_printer->is_active()) {
1214 FreeRegionListIterator iter(&local_cleanup_list);
1215 while (iter.more_available()) {
1216 HeapRegion* hr = iter.get_next();
1217 hr_printer->cleanup(hr);
1218 }
1219 }
1220
1221 _cleanup_list->add_ordered(&local_cleanup_list);
1222 assert(local_cleanup_list.is_empty(), "post-condition");
1223
1224 HeapRegionRemSet::finish_cleanup_task(&hrrs_cleanup_task);
1225 }
1226 }
1227 };
1228
1229 void G1ConcurrentMark::cleanup() {
1230 // world is stopped at this checkpoint
1231 assert(SafepointSynchronize::is_at_safepoint(),
1232 "world should be stopped");
1233 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1234
1235 // If a full collection has happened, we shouldn't do this.
1236 if (has_aborted()) {
1237 g1h->collector_state()->set_mark_in_progress(false); // So bitmap clearing isn't confused
1238 return;
1239 }
1240
1241 g1h->verifier()->verify_region_sets_optional();
1242
1243 if (VerifyDuringGC) {
1244 HandleMark hm; // handle scope
1245 g1h->prepare_for_verify();
1246 Universe::verify(VerifyOption_G1UsePrevMarking, "During GC (before)");
1247 }
1248 g1h->verifier()->check_bitmaps("Cleanup Start");
1249
1250 G1Policy* g1p = g1h->g1_policy();
1251 g1p->record_concurrent_mark_cleanup_start();
1252
1253 double start = os::elapsedTime();
1254
1255 HeapRegionRemSet::reset_for_cleanup_tasks();
1256
1257 {
1258 GCTraceTime(Debug, gc)("Finalize Live Data");
1259 finalize_live_data();
1260 }
1261
1262 if (VerifyDuringGC) {
1263 GCTraceTime(Debug, gc)("Verify Live Data");
1264 verify_live_data();
1265 }
1266
1267 g1h->collector_state()->set_mark_in_progress(false);
1268
1269 double count_end = os::elapsedTime();
1270 double this_final_counting_time = (count_end - start);
1271 _total_counting_time += this_final_counting_time;
1272
1273 if (log_is_enabled(Trace, gc, liveness)) {
1274 G1PrintRegionLivenessInfoClosure cl("Post-Marking");
1275 _g1h->heap_region_iterate(&cl);
1276 }
1277
1278 // Install newly created mark bitMap as "prev".
1279 swapMarkBitMaps();
1280
1281 g1h->reset_gc_time_stamp();
1282
1283 uint n_workers = _g1h->workers()->active_workers();
1284
1285 // Note end of marking in all heap regions.
1286 G1ParNoteEndTask g1_par_note_end_task(g1h, &_cleanup_list, n_workers);
1287 g1h->workers()->run_task(&g1_par_note_end_task);
1288 g1h->check_gc_time_stamps();
1289
1290 if (!cleanup_list_is_empty()) {
1291 // The cleanup list is not empty, so we'll have to process it
1292 // concurrently. Notify anyone else that might be wanting free
1293 // regions that there will be more free regions coming soon.
1294 g1h->set_free_regions_coming();
1295 }
1296
1297 // call below, since it affects the metric by which we sort the heap
1298 // regions.
1299 if (G1ScrubRemSets) {
1300 double rs_scrub_start = os::elapsedTime();
1301 g1h->scrub_rem_set();
1302 _total_rs_scrub_time += (os::elapsedTime() - rs_scrub_start);
1303 }
1304
1305 // this will also free any regions totally full of garbage objects,
1306 // and sort the regions.
1307 g1h->g1_policy()->record_concurrent_mark_cleanup_end();
1308
1309 // Statistics.
1310 double end = os::elapsedTime();
1311 _cleanup_times.add((end - start) * 1000.0);
1312
1313 // Clean up will have freed any regions completely full of garbage.
1314 // Update the soft reference policy with the new heap occupancy.
1315 Universe::update_heap_info_at_gc();
1316
1317 if (VerifyDuringGC) {
1318 HandleMark hm; // handle scope
1319 g1h->prepare_for_verify();
1320 Universe::verify(VerifyOption_G1UsePrevMarking, "During GC (after)");
1321 }
1322
1323 g1h->verifier()->check_bitmaps("Cleanup End");
1324
1325 g1h->verifier()->verify_region_sets_optional();
1326
1327 // We need to make this be a "collection" so any collection pause that
1328 // races with it goes around and waits for completeCleanup to finish.
1329 g1h->increment_total_collections();
1330
1331 // Clean out dead classes and update Metaspace sizes.
1332 if (ClassUnloadingWithConcurrentMark) {
1333 ClassLoaderDataGraph::purge();
1334 }
1335 MetaspaceGC::compute_new_size();
1336
1337 // We reclaimed old regions so we should calculate the sizes to make
1338 // sure we update the old gen/space data.
1339 g1h->g1mm()->update_sizes();
1340 g1h->allocation_context_stats().update_after_mark();
1341 }
1342
1343 void G1ConcurrentMark::complete_cleanup() {
1344 if (has_aborted()) return;
1345
1346 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1347
1348 _cleanup_list.verify_optional();
1349 FreeRegionList tmp_free_list("Tmp Free List");
1350
1351 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [complete cleanup] : "
1352 "cleanup list has %u entries",
1353 _cleanup_list.length());
1354
1355 // No one else should be accessing the _cleanup_list at this point,
1356 // so it is not necessary to take any locks
1357 while (!_cleanup_list.is_empty()) {
1358 HeapRegion* hr = _cleanup_list.remove_region(true /* from_head */);
1359 assert(hr != NULL, "Got NULL from a non-empty list");
1360 hr->par_clear();
1361 tmp_free_list.add_ordered(hr);
1362
1363 // Instead of adding one region at a time to the secondary_free_list,
1364 // we accumulate them in the local list and move them a few at a
1365 // time. This also cuts down on the number of notify_all() calls
1366 // we do during this process. We'll also append the local list when
1367 // _cleanup_list is empty (which means we just removed the last
1368 // region from the _cleanup_list).
1369 if ((tmp_free_list.length() % G1SecondaryFreeListAppendLength == 0) ||
1370 _cleanup_list.is_empty()) {
1371 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [complete cleanup] : "
1372 "appending %u entries to the secondary_free_list, "
1373 "cleanup list still has %u entries",
1374 tmp_free_list.length(),
1375 _cleanup_list.length());
1376
1377 {
1378 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
1379 g1h->secondary_free_list_add(&tmp_free_list);
1380 SecondaryFreeList_lock->notify_all();
1381 }
1382 #ifndef PRODUCT
1383 if (G1StressConcRegionFreeing) {
1384 for (uintx i = 0; i < G1StressConcRegionFreeingDelayMillis; ++i) {
1385 os::sleep(Thread::current(), (jlong) 1, false);
1386 }
1387 }
1388 #endif
1389 }
1390 }
1391 assert(tmp_free_list.is_empty(), "post-condition");
1392 }
1393
1394 // Supporting Object and Oop closures for reference discovery
1395 // and processing in during marking
1396
1397 bool G1CMIsAliveClosure::do_object_b(oop obj) {
1398 HeapWord* addr = (HeapWord*)obj;
1399 return addr != NULL &&
1400 (!_g1->is_in_g1_reserved(addr) || !_g1->is_obj_ill(obj));
1401 }
1402
1403 // 'Keep Alive' oop closure used by both serial parallel reference processing.
1404 // Uses the G1CMTask associated with a worker thread (for serial reference
1405 // processing the G1CMTask for worker 0 is used) to preserve (mark) and
1406 // trace referent objects.
1407 //
1408 // Using the G1CMTask and embedded local queues avoids having the worker
1409 // threads operating on the global mark stack. This reduces the risk
1410 // of overflowing the stack - which we would rather avoid at this late
1411 // state. Also using the tasks' local queues removes the potential
1412 // of the workers interfering with each other that could occur if
1413 // operating on the global stack.
1414
1415 class G1CMKeepAliveAndDrainClosure: public OopClosure {
1416 G1ConcurrentMark* _cm;
1417 G1CMTask* _task;
1418 int _ref_counter_limit;
1419 int _ref_counter;
1420 bool _is_serial;
1421 public:
1422 G1CMKeepAliveAndDrainClosure(G1ConcurrentMark* cm, G1CMTask* task, bool is_serial) :
1423 _cm(cm), _task(task), _is_serial(is_serial),
1424 _ref_counter_limit(G1RefProcDrainInterval) {
1425 assert(_ref_counter_limit > 0, "sanity");
1426 assert(!_is_serial || _task->worker_id() == 0, "only task 0 for serial code");
1427 _ref_counter = _ref_counter_limit;
1428 }
1429
1430 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
1431 virtual void do_oop( oop* p) { do_oop_work(p); }
1432
1433 template <class T> void do_oop_work(T* p) {
1434 if (!_cm->has_overflown()) {
1435 oop obj = oopDesc::load_decode_heap_oop(p);
1436 _task->deal_with_reference(obj);
1437 _ref_counter--;
1438
1439 if (_ref_counter == 0) {
1440 // We have dealt with _ref_counter_limit references, pushing them
1441 // and objects reachable from them on to the local stack (and
1442 // possibly the global stack). Call G1CMTask::do_marking_step() to
1443 // process these entries.
1444 //
1445 // We call G1CMTask::do_marking_step() in a loop, which we'll exit if
1446 // there's nothing more to do (i.e. we're done with the entries that
1447 // were pushed as a result of the G1CMTask::deal_with_reference() calls
1448 // above) or we overflow.
1449 //
1450 // Note: G1CMTask::do_marking_step() can set the G1CMTask::has_aborted()
1451 // flag while there may still be some work to do. (See the comment at
1452 // the beginning of G1CMTask::do_marking_step() for those conditions -
1453 // one of which is reaching the specified time target.) It is only
1454 // when G1CMTask::do_marking_step() returns without setting the
1455 // has_aborted() flag that the marking step has completed.
1456 do {
1457 double mark_step_duration_ms = G1ConcMarkStepDurationMillis;
1458 _task->do_marking_step(mark_step_duration_ms,
1459 false /* do_termination */,
1460 _is_serial);
1461 } while (_task->has_aborted() && !_cm->has_overflown());
1462 _ref_counter = _ref_counter_limit;
1463 }
1464 }
1465 }
1466 };
1467
1468 // 'Drain' oop closure used by both serial and parallel reference processing.
1469 // Uses the G1CMTask associated with a given worker thread (for serial
1470 // reference processing the G1CMtask for worker 0 is used). Calls the
1471 // do_marking_step routine, with an unbelievably large timeout value,
1472 // to drain the marking data structures of the remaining entries
1473 // added by the 'keep alive' oop closure above.
1474
1475 class G1CMDrainMarkingStackClosure: public VoidClosure {
1476 G1ConcurrentMark* _cm;
1477 G1CMTask* _task;
1478 bool _is_serial;
1479 public:
1480 G1CMDrainMarkingStackClosure(G1ConcurrentMark* cm, G1CMTask* task, bool is_serial) :
1481 _cm(cm), _task(task), _is_serial(is_serial) {
1482 assert(!_is_serial || _task->worker_id() == 0, "only task 0 for serial code");
1483 }
1484
1485 void do_void() {
1486 do {
1487 // We call G1CMTask::do_marking_step() to completely drain the local
1488 // and global marking stacks of entries pushed by the 'keep alive'
1489 // oop closure (an instance of G1CMKeepAliveAndDrainClosure above).
1490 //
1491 // G1CMTask::do_marking_step() is called in a loop, which we'll exit
1492 // if there's nothing more to do (i.e. we've completely drained the
1493 // entries that were pushed as a a result of applying the 'keep alive'
1494 // closure to the entries on the discovered ref lists) or we overflow
1495 // the global marking stack.
1496 //
1497 // Note: G1CMTask::do_marking_step() can set the G1CMTask::has_aborted()
1498 // flag while there may still be some work to do. (See the comment at
1499 // the beginning of G1CMTask::do_marking_step() for those conditions -
1500 // one of which is reaching the specified time target.) It is only
1501 // when G1CMTask::do_marking_step() returns without setting the
1502 // has_aborted() flag that the marking step has completed.
1503
1504 _task->do_marking_step(1000000000.0 /* something very large */,
1505 true /* do_termination */,
1506 _is_serial);
1507 } while (_task->has_aborted() && !_cm->has_overflown());
1508 }
1509 };
1510
1511 // Implementation of AbstractRefProcTaskExecutor for parallel
1512 // reference processing at the end of G1 concurrent marking
1513
1514 class G1CMRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
1515 private:
1516 G1CollectedHeap* _g1h;
1517 G1ConcurrentMark* _cm;
1518 WorkGang* _workers;
1519 uint _active_workers;
1520
1521 public:
1522 G1CMRefProcTaskExecutor(G1CollectedHeap* g1h,
1523 G1ConcurrentMark* cm,
1524 WorkGang* workers,
1525 uint n_workers) :
1526 _g1h(g1h), _cm(cm),
1527 _workers(workers), _active_workers(n_workers) { }
1528
1529 // Executes the given task using concurrent marking worker threads.
1530 virtual void execute(ProcessTask& task);
1531 virtual void execute(EnqueueTask& task);
1532 };
1533
1534 class G1CMRefProcTaskProxy: public AbstractGangTask {
1535 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
1536 ProcessTask& _proc_task;
1537 G1CollectedHeap* _g1h;
1538 G1ConcurrentMark* _cm;
1539
1540 public:
1541 G1CMRefProcTaskProxy(ProcessTask& proc_task,
1542 G1CollectedHeap* g1h,
1543 G1ConcurrentMark* cm) :
1544 AbstractGangTask("Process reference objects in parallel"),
1545 _proc_task(proc_task), _g1h(g1h), _cm(cm) {
1546 ReferenceProcessor* rp = _g1h->ref_processor_cm();
1547 assert(rp->processing_is_mt(), "shouldn't be here otherwise");
1548 }
1549
1550 virtual void work(uint worker_id) {
1551 ResourceMark rm;
1552 HandleMark hm;
1553 G1CMTask* task = _cm->task(worker_id);
1554 G1CMIsAliveClosure g1_is_alive(_g1h);
1555 G1CMKeepAliveAndDrainClosure g1_par_keep_alive(_cm, task, false /* is_serial */);
1556 G1CMDrainMarkingStackClosure g1_par_drain(_cm, task, false /* is_serial */);
1557
1558 _proc_task.work(worker_id, g1_is_alive, g1_par_keep_alive, g1_par_drain);
1559 }
1560 };
1561
1562 void G1CMRefProcTaskExecutor::execute(ProcessTask& proc_task) {
1563 assert(_workers != NULL, "Need parallel worker threads.");
1564 assert(_g1h->ref_processor_cm()->processing_is_mt(), "processing is not MT");
1565
1566 G1CMRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _cm);
1567
1568 // We need to reset the concurrency level before each
1569 // proxy task execution, so that the termination protocol
1570 // and overflow handling in G1CMTask::do_marking_step() knows
1571 // how many workers to wait for.
1572 _cm->set_concurrency(_active_workers);
1573 _workers->run_task(&proc_task_proxy);
1574 }
1575
1576 class G1CMRefEnqueueTaskProxy: public AbstractGangTask {
1577 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
1578 EnqueueTask& _enq_task;
1579
1580 public:
1581 G1CMRefEnqueueTaskProxy(EnqueueTask& enq_task) :
1582 AbstractGangTask("Enqueue reference objects in parallel"),
1583 _enq_task(enq_task) { }
1584
1585 virtual void work(uint worker_id) {
1586 _enq_task.work(worker_id);
1587 }
1588 };
1589
1590 void G1CMRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
1591 assert(_workers != NULL, "Need parallel worker threads.");
1592 assert(_g1h->ref_processor_cm()->processing_is_mt(), "processing is not MT");
1593
1594 G1CMRefEnqueueTaskProxy enq_task_proxy(enq_task);
1595
1596 // Not strictly necessary but...
1597 //
1598 // We need to reset the concurrency level before each
1599 // proxy task execution, so that the termination protocol
1600 // and overflow handling in G1CMTask::do_marking_step() knows
1601 // how many workers to wait for.
1602 _cm->set_concurrency(_active_workers);
1603 _workers->run_task(&enq_task_proxy);
1604 }
1605
1606 void G1ConcurrentMark::weakRefsWorkParallelPart(BoolObjectClosure* is_alive, bool purged_classes) {
1607 G1CollectedHeap::heap()->parallel_cleaning(is_alive, true, true, purged_classes);
1608 }
1609
1610 void G1ConcurrentMark::weakRefsWork(bool clear_all_soft_refs) {
1611 if (has_overflown()) {
1612 // Skip processing the discovered references if we have
1613 // overflown the global marking stack. Reference objects
1614 // only get discovered once so it is OK to not
1615 // de-populate the discovered reference lists. We could have,
1616 // but the only benefit would be that, when marking restarts,
1617 // less reference objects are discovered.
1618 return;
1619 }
1620
1621 ResourceMark rm;
1622 HandleMark hm;
1623
1624 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1625
1626 // Is alive closure.
1627 G1CMIsAliveClosure g1_is_alive(g1h);
1628
1629 // Inner scope to exclude the cleaning of the string and symbol
1630 // tables from the displayed time.
1631 {
1632 GCTraceTime(Debug, gc, phases) trace("Reference Processing", _gc_timer_cm);
1633
1634 ReferenceProcessor* rp = g1h->ref_processor_cm();
1635
1636 // See the comment in G1CollectedHeap::ref_processing_init()
1637 // about how reference processing currently works in G1.
1638
1639 // Set the soft reference policy
1640 rp->setup_policy(clear_all_soft_refs);
1641 assert(_global_mark_stack.is_empty(), "mark stack should be empty");
1642
1643 // Instances of the 'Keep Alive' and 'Complete GC' closures used
1644 // in serial reference processing. Note these closures are also
1645 // used for serially processing (by the the current thread) the
1646 // JNI references during parallel reference processing.
1647 //
1648 // These closures do not need to synchronize with the worker
1649 // threads involved in parallel reference processing as these
1650 // instances are executed serially by the current thread (e.g.
1651 // reference processing is not multi-threaded and is thus
1652 // performed by the current thread instead of a gang worker).
1653 //
1654 // The gang tasks involved in parallel reference processing create
1655 // their own instances of these closures, which do their own
1656 // synchronization among themselves.
1657 G1CMKeepAliveAndDrainClosure g1_keep_alive(this, task(0), true /* is_serial */);
1658 G1CMDrainMarkingStackClosure g1_drain_mark_stack(this, task(0), true /* is_serial */);
1659
1660 // We need at least one active thread. If reference processing
1661 // is not multi-threaded we use the current (VMThread) thread,
1662 // otherwise we use the work gang from the G1CollectedHeap and
1663 // we utilize all the worker threads we can.
1664 bool processing_is_mt = rp->processing_is_mt();
1665 uint active_workers = (processing_is_mt ? g1h->workers()->active_workers() : 1U);
1666 active_workers = MAX2(MIN2(active_workers, _max_worker_id), 1U);
1667
1668 // Parallel processing task executor.
1669 G1CMRefProcTaskExecutor par_task_executor(g1h, this,
1670 g1h->workers(), active_workers);
1671 AbstractRefProcTaskExecutor* executor = (processing_is_mt ? &par_task_executor : NULL);
1672
1673 // Set the concurrency level. The phase was already set prior to
1674 // executing the remark task.
1675 set_concurrency(active_workers);
1676
1677 // Set the degree of MT processing here. If the discovery was done MT,
1678 // the number of threads involved during discovery could differ from
1679 // the number of active workers. This is OK as long as the discovered
1680 // Reference lists are balanced (see balance_all_queues() and balance_queues()).
1681 rp->set_active_mt_degree(active_workers);
1682
1683 // Process the weak references.
1684 const ReferenceProcessorStats& stats =
1685 rp->process_discovered_references(&g1_is_alive,
1686 &g1_keep_alive,
1687 &g1_drain_mark_stack,
1688 executor,
1689 _gc_timer_cm);
1690 _gc_tracer_cm->report_gc_reference_stats(stats);
1691
1692 // The do_oop work routines of the keep_alive and drain_marking_stack
1693 // oop closures will set the has_overflown flag if we overflow the
1694 // global marking stack.
1695
1696 assert(_global_mark_stack.overflow() || _global_mark_stack.is_empty(),
1697 "mark stack should be empty (unless it overflowed)");
1698
1699 if (_global_mark_stack.overflow()) {
1700 // This should have been done already when we tried to push an
1701 // entry on to the global mark stack. But let's do it again.
1702 set_has_overflown();
1703 }
1704
1705 assert(rp->num_q() == active_workers, "why not");
1706
1707 rp->enqueue_discovered_references(executor);
1708
1709 rp->verify_no_references_recorded();
1710 assert(!rp->discovery_enabled(), "Post condition");
1711 }
1712
1713 if (has_overflown()) {
1714 // We can not trust g1_is_alive if the marking stack overflowed
1715 return;
1716 }
1717
1718 assert(_global_mark_stack.is_empty(), "Marking should have completed");
1719
1720 // Unload Klasses, String, Symbols, Code Cache, etc.
1721 if (ClassUnloadingWithConcurrentMark) {
1722 bool purged_classes;
1723
1724 {
1725 GCTraceTime(Debug, gc, phases) trace("System Dictionary Unloading", _gc_timer_cm);
1726 purged_classes = SystemDictionary::do_unloading(&g1_is_alive, false /* Defer klass cleaning */);
1727 }
1728
1729 {
1730 GCTraceTime(Debug, gc, phases) trace("Parallel Unloading", _gc_timer_cm);
1731 weakRefsWorkParallelPart(&g1_is_alive, purged_classes);
1732 }
1733 }
1734
1735 if (G1StringDedup::is_enabled()) {
1736 GCTraceTime(Debug, gc, phases) trace("String Deduplication Unlink", _gc_timer_cm);
1737 G1StringDedup::unlink(&g1_is_alive);
1738 }
1739 }
1740
1741 void G1ConcurrentMark::swapMarkBitMaps() {
1742 G1CMBitMapRO* temp = _prevMarkBitMap;
1743 _prevMarkBitMap = (G1CMBitMapRO*)_nextMarkBitMap;
1744 _nextMarkBitMap = (G1CMBitMap*) temp;
1745 }
1746
1747 // Closure for marking entries in SATB buffers.
1748 class G1CMSATBBufferClosure : public SATBBufferClosure {
1749 private:
1750 G1CMTask* _task;
1751 G1CollectedHeap* _g1h;
1752
1753 // This is very similar to G1CMTask::deal_with_reference, but with
1754 // more relaxed requirements for the argument, so this must be more
1755 // circumspect about treating the argument as an object.
1756 void do_entry(void* entry) const {
1757 _task->increment_refs_reached();
1758 HeapRegion* hr = _g1h->heap_region_containing(entry);
1759 if (entry < hr->next_top_at_mark_start()) {
1760 // Until we get here, we don't know whether entry refers to a valid
1761 // object; it could instead have been a stale reference.
1762 oop obj = static_cast<oop>(entry);
1763 assert(obj->is_oop(true /* ignore mark word */),
1764 "Invalid oop in SATB buffer: " PTR_FORMAT, p2i(obj));
1765 _task->make_reference_grey(obj);
1766 }
1767 }
1768
1769 public:
1770 G1CMSATBBufferClosure(G1CMTask* task, G1CollectedHeap* g1h)
1771 : _task(task), _g1h(g1h) { }
1772
1773 virtual void do_buffer(void** buffer, size_t size) {
1774 for (size_t i = 0; i < size; ++i) {
1775 do_entry(buffer[i]);
1776 }
1777 }
1778 };
1779
1780 class G1RemarkThreadsClosure : public ThreadClosure {
1781 G1CMSATBBufferClosure _cm_satb_cl;
1782 G1CMOopClosure _cm_cl;
1783 MarkingCodeBlobClosure _code_cl;
1784 int _thread_parity;
1785
1786 public:
1787 G1RemarkThreadsClosure(G1CollectedHeap* g1h, G1CMTask* task) :
1788 _cm_satb_cl(task, g1h),
1789 _cm_cl(g1h, g1h->concurrent_mark(), task),
1790 _code_cl(&_cm_cl, !CodeBlobToOopClosure::FixRelocations),
1791 _thread_parity(Threads::thread_claim_parity()) {}
1792
1793 void do_thread(Thread* thread) {
1794 if (thread->is_Java_thread()) {
1795 if (thread->claim_oops_do(true, _thread_parity)) {
1796 JavaThread* jt = (JavaThread*)thread;
1797
1798 // In theory it should not be neccessary to explicitly walk the nmethods to find roots for concurrent marking
1799 // however the liveness of oops reachable from nmethods have very complex lifecycles:
1800 // * Alive if on the stack of an executing method
1801 // * Weakly reachable otherwise
1802 // Some objects reachable from nmethods, such as the class loader (or klass_holder) of the receiver should be
1803 // live by the SATB invariant but other oops recorded in nmethods may behave differently.
1804 jt->nmethods_do(&_code_cl);
1805
1806 jt->satb_mark_queue().apply_closure_and_empty(&_cm_satb_cl);
1807 }
1808 } else if (thread->is_VM_thread()) {
1809 if (thread->claim_oops_do(true, _thread_parity)) {
1810 JavaThread::satb_mark_queue_set().shared_satb_queue()->apply_closure_and_empty(&_cm_satb_cl);
1811 }
1812 }
1813 }
1814 };
1815
1816 class G1CMRemarkTask: public AbstractGangTask {
1817 private:
1818 G1ConcurrentMark* _cm;
1819 public:
1820 void work(uint worker_id) {
1821 // Since all available tasks are actually started, we should
1822 // only proceed if we're supposed to be active.
1823 if (worker_id < _cm->active_tasks()) {
1824 G1CMTask* task = _cm->task(worker_id);
1825 task->record_start_time();
1826 {
1827 ResourceMark rm;
1828 HandleMark hm;
1829
1830 G1RemarkThreadsClosure threads_f(G1CollectedHeap::heap(), task);
1831 Threads::threads_do(&threads_f);
1832 }
1833
1834 do {
1835 task->do_marking_step(1000000000.0 /* something very large */,
1836 true /* do_termination */,
1837 false /* is_serial */);
1838 } while (task->has_aborted() && !_cm->has_overflown());
1839 // If we overflow, then we do not want to restart. We instead
1840 // want to abort remark and do concurrent marking again.
1841 task->record_end_time();
1842 }
1843 }
1844
1845 G1CMRemarkTask(G1ConcurrentMark* cm, uint active_workers) :
1846 AbstractGangTask("Par Remark"), _cm(cm) {
1847 _cm->terminator()->reset_for_reuse(active_workers);
1848 }
1849 };
1850
1851 void G1ConcurrentMark::checkpointRootsFinalWork() {
1852 ResourceMark rm;
1853 HandleMark hm;
1854 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1855
1856 GCTraceTime(Debug, gc, phases) trace("Finalize Marking", _gc_timer_cm);
1857
1858 g1h->ensure_parsability(false);
1859
1860 // this is remark, so we'll use up all active threads
1861 uint active_workers = g1h->workers()->active_workers();
1862 set_concurrency_and_phase(active_workers, false /* concurrent */);
1863 // Leave _parallel_marking_threads at it's
1864 // value originally calculated in the G1ConcurrentMark
1865 // constructor and pass values of the active workers
1866 // through the gang in the task.
1867
1868 {
1869 StrongRootsScope srs(active_workers);
1870
1871 G1CMRemarkTask remarkTask(this, active_workers);
1872 // We will start all available threads, even if we decide that the
1873 // active_workers will be fewer. The extra ones will just bail out
1874 // immediately.
1875 g1h->workers()->run_task(&remarkTask);
1876 }
1877
1878 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
1879 guarantee(has_overflown() ||
1880 satb_mq_set.completed_buffers_num() == 0,
1881 "Invariant: has_overflown = %s, num buffers = " SIZE_FORMAT,
1882 BOOL_TO_STR(has_overflown()),
1883 satb_mq_set.completed_buffers_num());
1884
1885 print_stats();
1886 }
1887
1888 void G1ConcurrentMark::clearRangePrevBitmap(MemRegion mr) {
1889 // Note we are overriding the read-only view of the prev map here, via
1890 // the cast.
1891 ((G1CMBitMap*)_prevMarkBitMap)->clear_range(mr);
1892 }
1893
1894 HeapRegion*
1895 G1ConcurrentMark::claim_region(uint worker_id) {
1896 // "checkpoint" the finger
1897 HeapWord* finger = _finger;
1898
1899 // _heap_end will not change underneath our feet; it only changes at
1900 // yield points.
1901 while (finger < _heap_end) {
1902 assert(_g1h->is_in_g1_reserved(finger), "invariant");
1903
1904 HeapRegion* curr_region = _g1h->heap_region_containing(finger);
1905
1906 // Above heap_region_containing may return NULL as we always scan claim
1907 // until the end of the heap. In this case, just jump to the next region.
1908 HeapWord* end = curr_region != NULL ? curr_region->end() : finger + HeapRegion::GrainWords;
1909
1910 // Is the gap between reading the finger and doing the CAS too long?
1911 HeapWord* res = (HeapWord*) Atomic::cmpxchg_ptr(end, &_finger, finger);
1912 if (res == finger && curr_region != NULL) {
1913 // we succeeded
1914 HeapWord* bottom = curr_region->bottom();
1915 HeapWord* limit = curr_region->next_top_at_mark_start();
1916
1917 // notice that _finger == end cannot be guaranteed here since,
1918 // someone else might have moved the finger even further
1919 assert(_finger >= end, "the finger should have moved forward");
1920
1921 if (limit > bottom) {
1922 return curr_region;
1923 } else {
1924 assert(limit == bottom,
1925 "the region limit should be at bottom");
1926 // we return NULL and the caller should try calling
1927 // claim_region() again.
1928 return NULL;
1929 }
1930 } else {
1931 assert(_finger > finger, "the finger should have moved forward");
1932 // read it again
1933 finger = _finger;
1934 }
1935 }
1936
1937 return NULL;
1938 }
1939
1940 #ifndef PRODUCT
1941 class VerifyNoCSetOops VALUE_OBJ_CLASS_SPEC {
1942 private:
1943 G1CollectedHeap* _g1h;
1944 const char* _phase;
1945 int _info;
1946
1947 public:
1948 VerifyNoCSetOops(const char* phase, int info = -1) :
1949 _g1h(G1CollectedHeap::heap()),
1950 _phase(phase),
1951 _info(info)
1952 { }
1953
1954 void operator()(oop obj) const {
1955 guarantee(obj->is_oop(),
1956 "Non-oop " PTR_FORMAT ", phase: %s, info: %d",
1957 p2i(obj), _phase, _info);
1958 guarantee(!_g1h->obj_in_cs(obj),
1959 "obj: " PTR_FORMAT " in CSet, phase: %s, info: %d",
1960 p2i(obj), _phase, _info);
1961 }
1962 };
1963
1964 void G1ConcurrentMark::verify_no_cset_oops() {
1965 assert(SafepointSynchronize::is_at_safepoint(), "should be at a safepoint");
1966 if (!G1CollectedHeap::heap()->collector_state()->mark_in_progress()) {
1967 return;
1968 }
1969
1970 // Verify entries on the global mark stack
1971 _global_mark_stack.iterate(VerifyNoCSetOops("Stack"));
1972
1973 // Verify entries on the task queues
1974 for (uint i = 0; i < _max_worker_id; ++i) {
1975 G1CMTaskQueue* queue = _task_queues->queue(i);
1976 queue->iterate(VerifyNoCSetOops("Queue", i));
1977 }
1978
1979 // Verify the global finger
1980 HeapWord* global_finger = finger();
1981 if (global_finger != NULL && global_finger < _heap_end) {
1982 // Since we always iterate over all regions, we might get a NULL HeapRegion
1983 // here.
1984 HeapRegion* global_hr = _g1h->heap_region_containing(global_finger);
1985 guarantee(global_hr == NULL || global_finger == global_hr->bottom(),
1986 "global finger: " PTR_FORMAT " region: " HR_FORMAT,
1987 p2i(global_finger), HR_FORMAT_PARAMS(global_hr));
1988 }
1989
1990 // Verify the task fingers
1991 assert(parallel_marking_threads() <= _max_worker_id, "sanity");
1992 for (uint i = 0; i < parallel_marking_threads(); ++i) {
1993 G1CMTask* task = _tasks[i];
1994 HeapWord* task_finger = task->finger();
1995 if (task_finger != NULL && task_finger < _heap_end) {
1996 // See above note on the global finger verification.
1997 HeapRegion* task_hr = _g1h->heap_region_containing(task_finger);
1998 guarantee(task_hr == NULL || task_finger == task_hr->bottom() ||
1999 !task_hr->in_collection_set(),
2000 "task finger: " PTR_FORMAT " region: " HR_FORMAT,
2001 p2i(task_finger), HR_FORMAT_PARAMS(task_hr));
2002 }
2003 }
2004 }
2005 #endif // PRODUCT
2006 void G1ConcurrentMark::create_live_data() {
2007 _g1h->g1_rem_set()->create_card_live_data(_parallel_workers, _nextMarkBitMap);
2008 }
2009
2010 void G1ConcurrentMark::finalize_live_data() {
2011 _g1h->g1_rem_set()->finalize_card_live_data(_g1h->workers(), _nextMarkBitMap);
2012 }
2013
2014 void G1ConcurrentMark::verify_live_data() {
2015 _g1h->g1_rem_set()->verify_card_live_data(_g1h->workers(), _nextMarkBitMap);
2016 }
2017
2018 void G1ConcurrentMark::clear_live_data(WorkGang* workers) {
2019 _g1h->g1_rem_set()->clear_card_live_data(workers);
2020 }
2021
2022 #ifdef ASSERT
2023 void G1ConcurrentMark::verify_live_data_clear() {
2024 _g1h->g1_rem_set()->verify_card_live_data_is_clear();
2025 }
2026 #endif
2027
2028 void G1ConcurrentMark::print_stats() {
2029 if (!log_is_enabled(Debug, gc, stats)) {
2030 return;
2031 }
2032 log_debug(gc, stats)("---------------------------------------------------------------------");
2033 for (size_t i = 0; i < _active_tasks; ++i) {
2034 _tasks[i]->print_stats();
2035 log_debug(gc, stats)("---------------------------------------------------------------------");
2036 }
2037 }
2038
2039 void G1ConcurrentMark::abort() {
2040 if (!cmThread()->during_cycle() || _has_aborted) {
2041 // We haven't started a concurrent cycle or we have already aborted it. No need to do anything.
2042 return;
2043 }
2044
2045 // Clear all marks in the next bitmap for the next marking cycle. This will allow us to skip the next
2046 // concurrent bitmap clearing.
2047 {
2048 GCTraceTime(Debug, gc)("Clear Next Bitmap");
2049 clear_bitmap(_nextMarkBitMap, _g1h->workers(), false);
2050 }
2051 // Note we cannot clear the previous marking bitmap here
2052 // since VerifyDuringGC verifies the objects marked during
2053 // a full GC against the previous bitmap.
2054
2055 {
2056 GCTraceTime(Debug, gc)("Clear Live Data");
2057 clear_live_data(_g1h->workers());
2058 }
2059 DEBUG_ONLY({
2060 GCTraceTime(Debug, gc)("Verify Live Data Clear");
2061 verify_live_data_clear();
2062 })
2063 // Empty mark stack
2064 reset_marking_state();
2065 for (uint i = 0; i < _max_worker_id; ++i) {
2066 _tasks[i]->clear_region_fields();
2067 }
2068 _first_overflow_barrier_sync.abort();
2069 _second_overflow_barrier_sync.abort();
2070 _has_aborted = true;
2071
2072 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
2073 satb_mq_set.abandon_partial_marking();
2074 // This can be called either during or outside marking, we'll read
2075 // the expected_active value from the SATB queue set.
2076 satb_mq_set.set_active_all_threads(
2077 false, /* new active value */
2078 satb_mq_set.is_active() /* expected_active */);
2079 }
2080
2081 static void print_ms_time_info(const char* prefix, const char* name,
2082 NumberSeq& ns) {
2083 log_trace(gc, marking)("%s%5d %12s: total time = %8.2f s (avg = %8.2f ms).",
2084 prefix, ns.num(), name, ns.sum()/1000.0, ns.avg());
2085 if (ns.num() > 0) {
2086 log_trace(gc, marking)("%s [std. dev = %8.2f ms, max = %8.2f ms]",
2087 prefix, ns.sd(), ns.maximum());
2088 }
2089 }
2090
2091 void G1ConcurrentMark::print_summary_info() {
2092 Log(gc, marking) log;
2093 if (!log.is_trace()) {
2094 return;
2095 }
2096
2097 log.trace(" Concurrent marking:");
2098 print_ms_time_info(" ", "init marks", _init_times);
2099 print_ms_time_info(" ", "remarks", _remark_times);
2100 {
2101 print_ms_time_info(" ", "final marks", _remark_mark_times);
2102 print_ms_time_info(" ", "weak refs", _remark_weak_ref_times);
2103
2104 }
2105 print_ms_time_info(" ", "cleanups", _cleanup_times);
2106 log.trace(" Finalize live data total time = %8.2f s (avg = %8.2f ms).",
2107 _total_counting_time, (_cleanup_times.num() > 0 ? _total_counting_time * 1000.0 / (double)_cleanup_times.num() : 0.0));
2108 if (G1ScrubRemSets) {
2109 log.trace(" RS scrub total time = %8.2f s (avg = %8.2f ms).",
2110 _total_rs_scrub_time, (_cleanup_times.num() > 0 ? _total_rs_scrub_time * 1000.0 / (double)_cleanup_times.num() : 0.0));
2111 }
2112 log.trace(" Total stop_world time = %8.2f s.",
2113 (_init_times.sum() + _remark_times.sum() + _cleanup_times.sum())/1000.0);
2114 log.trace(" Total concurrent time = %8.2f s (%8.2f s marking).",
2115 cmThread()->vtime_accum(), cmThread()->vtime_mark_accum());
2116 }
2117
2118 void G1ConcurrentMark::print_worker_threads_on(outputStream* st) const {
2119 _parallel_workers->print_worker_threads_on(st);
2120 }
2121
2122 void G1ConcurrentMark::threads_do(ThreadClosure* tc) const {
2123 _parallel_workers->threads_do(tc);
2124 }
2125
2126 void G1ConcurrentMark::print_on_error(outputStream* st) const {
2127 st->print_cr("Marking Bits (Prev, Next): (CMBitMap*) " PTR_FORMAT ", (CMBitMap*) " PTR_FORMAT,
2128 p2i(_prevMarkBitMap), p2i(_nextMarkBitMap));
2129 _prevMarkBitMap->print_on_error(st, " Prev Bits: ");
2130 _nextMarkBitMap->print_on_error(st, " Next Bits: ");
2131 }
2132
2133 // Closure for iteration over bitmaps
2134 class G1CMBitMapClosure : public BitMapClosure {
2135 private:
2136 // the bitmap that is being iterated over
2137 G1CMBitMap* _nextMarkBitMap;
2138 G1ConcurrentMark* _cm;
2139 G1CMTask* _task;
2140
2141 public:
2142 G1CMBitMapClosure(G1CMTask *task, G1ConcurrentMark* cm, G1CMBitMap* nextMarkBitMap) :
2143 _task(task), _cm(cm), _nextMarkBitMap(nextMarkBitMap) { }
2144
2145 bool do_bit(size_t offset) {
2146 HeapWord* addr = _nextMarkBitMap->offsetToHeapWord(offset);
2147 assert(_nextMarkBitMap->isMarked(addr), "invariant");
2148 assert( addr < _cm->finger(), "invariant");
2149 assert(addr >= _task->finger(), "invariant");
2150
2151 // We move that task's local finger along.
2152 _task->move_finger_to(addr);
2153
2154 _task->scan_object(oop(addr));
2155 // we only partially drain the local queue and global stack
2156 _task->drain_local_queue(true);
2157 _task->drain_global_stack(true);
2158
2159 // if the has_aborted flag has been raised, we need to bail out of
2160 // the iteration
2161 return !_task->has_aborted();
2162 }
2163 };
2164
2165 static ReferenceProcessor* get_cm_oop_closure_ref_processor(G1CollectedHeap* g1h) {
2166 ReferenceProcessor* result = g1h->ref_processor_cm();
2167 assert(result != NULL, "CM reference processor should not be NULL");
2168 return result;
2169 }
2170
2171 G1CMOopClosure::G1CMOopClosure(G1CollectedHeap* g1h,
2172 G1ConcurrentMark* cm,
2173 G1CMTask* task)
2174 : MetadataAwareOopClosure(get_cm_oop_closure_ref_processor(g1h)),
2175 _g1h(g1h), _cm(cm), _task(task)
2176 { }
2177
2178 void G1CMTask::setup_for_region(HeapRegion* hr) {
2179 assert(hr != NULL,
2180 "claim_region() should have filtered out NULL regions");
2181 _curr_region = hr;
2182 _finger = hr->bottom();
2183 update_region_limit();
2184 }
2185
2186 void G1CMTask::update_region_limit() {
2187 HeapRegion* hr = _curr_region;
2188 HeapWord* bottom = hr->bottom();
2189 HeapWord* limit = hr->next_top_at_mark_start();
2190
2191 if (limit == bottom) {
2192 // The region was collected underneath our feet.
2193 // We set the finger to bottom to ensure that the bitmap
2194 // iteration that will follow this will not do anything.
2195 // (this is not a condition that holds when we set the region up,
2196 // as the region is not supposed to be empty in the first place)
2197 _finger = bottom;
2198 } else if (limit >= _region_limit) {
2199 assert(limit >= _finger, "peace of mind");
2200 } else {
2201 assert(limit < _region_limit, "only way to get here");
2202 // This can happen under some pretty unusual circumstances. An
2203 // evacuation pause empties the region underneath our feet (NTAMS
2204 // at bottom). We then do some allocation in the region (NTAMS
2205 // stays at bottom), followed by the region being used as a GC
2206 // alloc region (NTAMS will move to top() and the objects
2207 // originally below it will be grayed). All objects now marked in
2208 // the region are explicitly grayed, if below the global finger,
2209 // and we do not need in fact to scan anything else. So, we simply
2210 // set _finger to be limit to ensure that the bitmap iteration
2211 // doesn't do anything.
2212 _finger = limit;
2213 }
2214
2215 _region_limit = limit;
2216 }
2217
2218 void G1CMTask::giveup_current_region() {
2219 assert(_curr_region != NULL, "invariant");
2220 clear_region_fields();
2221 }
2222
2223 void G1CMTask::clear_region_fields() {
2224 // Values for these three fields that indicate that we're not
2225 // holding on to a region.
2226 _curr_region = NULL;
2227 _finger = NULL;
2228 _region_limit = NULL;
2229 }
2230
2231 void G1CMTask::set_cm_oop_closure(G1CMOopClosure* cm_oop_closure) {
2232 if (cm_oop_closure == NULL) {
2233 assert(_cm_oop_closure != NULL, "invariant");
2234 } else {
2235 assert(_cm_oop_closure == NULL, "invariant");
2236 }
2237 _cm_oop_closure = cm_oop_closure;
2238 }
2239
2240 void G1CMTask::reset(G1CMBitMap* nextMarkBitMap) {
2241 guarantee(nextMarkBitMap != NULL, "invariant");
2242 _nextMarkBitMap = nextMarkBitMap;
2243 clear_region_fields();
2244
2245 _calls = 0;
2246 _elapsed_time_ms = 0.0;
2247 _termination_time_ms = 0.0;
2248 _termination_start_time_ms = 0.0;
2249 }
2250
2251 bool G1CMTask::should_exit_termination() {
2252 regular_clock_call();
2253 // This is called when we are in the termination protocol. We should
2254 // quit if, for some reason, this task wants to abort or the global
2255 // stack is not empty (this means that we can get work from it).
2256 return !_cm->mark_stack_empty() || has_aborted();
2257 }
2258
2259 void G1CMTask::reached_limit() {
2260 assert(_words_scanned >= _words_scanned_limit ||
2261 _refs_reached >= _refs_reached_limit ,
2262 "shouldn't have been called otherwise");
2263 regular_clock_call();
2264 }
2265
2266 void G1CMTask::regular_clock_call() {
2267 if (has_aborted()) return;
2268
2269 // First, we need to recalculate the words scanned and refs reached
2270 // limits for the next clock call.
2271 recalculate_limits();
2272
2273 // During the regular clock call we do the following
2274
2275 // (1) If an overflow has been flagged, then we abort.
2276 if (_cm->has_overflown()) {
2277 set_has_aborted();
2278 return;
2279 }
2280
2281 // If we are not concurrent (i.e. we're doing remark) we don't need
2282 // to check anything else. The other steps are only needed during
2283 // the concurrent marking phase.
2284 if (!concurrent()) return;
2285
2286 // (2) If marking has been aborted for Full GC, then we also abort.
2287 if (_cm->has_aborted()) {
2288 set_has_aborted();
2289 return;
2290 }
2291
2292 double curr_time_ms = os::elapsedVTime() * 1000.0;
2293
2294 // (4) We check whether we should yield. If we have to, then we abort.
2295 if (SuspendibleThreadSet::should_yield()) {
2296 // We should yield. To do this we abort the task. The caller is
2297 // responsible for yielding.
2298 set_has_aborted();
2299 return;
2300 }
2301
2302 // (5) We check whether we've reached our time quota. If we have,
2303 // then we abort.
2304 double elapsed_time_ms = curr_time_ms - _start_time_ms;
2305 if (elapsed_time_ms > _time_target_ms) {
2306 set_has_aborted();
2307 _has_timed_out = true;
2308 return;
2309 }
2310
2311 // (6) Finally, we check whether there are enough completed STAB
2312 // buffers available for processing. If there are, we abort.
2313 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
2314 if (!_draining_satb_buffers && satb_mq_set.process_completed_buffers()) {
2315 // we do need to process SATB buffers, we'll abort and restart
2316 // the marking task to do so
2317 set_has_aborted();
2318 return;
2319 }
2320 }
2321
2322 void G1CMTask::recalculate_limits() {
2323 _real_words_scanned_limit = _words_scanned + words_scanned_period;
2324 _words_scanned_limit = _real_words_scanned_limit;
2325
2326 _real_refs_reached_limit = _refs_reached + refs_reached_period;
2327 _refs_reached_limit = _real_refs_reached_limit;
2328 }
2329
2330 void G1CMTask::decrease_limits() {
2331 // This is called when we believe that we're going to do an infrequent
2332 // operation which will increase the per byte scanned cost (i.e. move
2333 // entries to/from the global stack). It basically tries to decrease the
2334 // scanning limit so that the clock is called earlier.
2335
2336 _words_scanned_limit = _real_words_scanned_limit -
2337 3 * words_scanned_period / 4;
2338 _refs_reached_limit = _real_refs_reached_limit -
2339 3 * refs_reached_period / 4;
2340 }
2341
2342 void G1CMTask::move_entries_to_global_stack() {
2343 // local array where we'll store the entries that will be popped
2344 // from the local queue
2345 oop buffer[global_stack_transfer_size];
2346
2347 int n = 0;
2348 oop obj;
2349 while (n < global_stack_transfer_size && _task_queue->pop_local(obj)) {
2350 buffer[n] = obj;
2351 ++n;
2352 }
2353
2354 if (n > 0) {
2355 // we popped at least one entry from the local queue
2356
2357 if (!_cm->mark_stack_push(buffer, n)) {
2358 set_has_aborted();
2359 }
2360 }
2361
2362 // this operation was quite expensive, so decrease the limits
2363 decrease_limits();
2364 }
2365
2366 void G1CMTask::get_entries_from_global_stack() {
2367 // local array where we'll store the entries that will be popped
2368 // from the global stack.
2369 oop buffer[global_stack_transfer_size];
2370 size_t n;
2371 _cm->mark_stack_pop(buffer, global_stack_transfer_size, &n);
2372 assert(n <= global_stack_transfer_size,
2373 "we should not pop more than the given limit");
2374 if (n > 0) {
2375 // yes, we did actually pop at least one entry
2376 for (size_t i = 0; i < n; ++i) {
2377 bool success = _task_queue->push(buffer[i]);
2378 // We only call this when the local queue is empty or under a
2379 // given target limit. So, we do not expect this push to fail.
2380 assert(success, "invariant");
2381 }
2382 }
2383
2384 // this operation was quite expensive, so decrease the limits
2385 decrease_limits();
2386 }
2387
2388 void G1CMTask::drain_local_queue(bool partially) {
2389 if (has_aborted()) return;
2390
2391 // Decide what the target size is, depending whether we're going to
2392 // drain it partially (so that other tasks can steal if they run out
2393 // of things to do) or totally (at the very end).
2394 size_t target_size;
2395 if (partially) {
2396 target_size = MIN2((size_t)_task_queue->max_elems()/3, GCDrainStackTargetSize);
2397 } else {
2398 target_size = 0;
2399 }
2400
2401 if (_task_queue->size() > target_size) {
2402 oop obj;
2403 bool ret = _task_queue->pop_local(obj);
2404 while (ret) {
2405 assert(_g1h->is_in_g1_reserved((HeapWord*) obj), "invariant" );
2406 assert(!_g1h->is_on_master_free_list(
2407 _g1h->heap_region_containing((HeapWord*) obj)), "invariant");
2408
2409 scan_object(obj);
2410
2411 if (_task_queue->size() <= target_size || has_aborted()) {
2412 ret = false;
2413 } else {
2414 ret = _task_queue->pop_local(obj);
2415 }
2416 }
2417 }
2418 }
2419
2420 void G1CMTask::drain_global_stack(bool partially) {
2421 if (has_aborted()) return;
2422
2423 // We have a policy to drain the local queue before we attempt to
2424 // drain the global stack.
2425 assert(partially || _task_queue->size() == 0, "invariant");
2426
2427 // Decide what the target size is, depending whether we're going to
2428 // drain it partially (so that other tasks can steal if they run out
2429 // of things to do) or totally (at the very end). Notice that,
2430 // because we move entries from the global stack in chunks or
2431 // because another task might be doing the same, we might in fact
2432 // drop below the target. But, this is not a problem.
2433 size_t target_size;
2434 if (partially) {
2435 target_size = _cm->partial_mark_stack_size_target();
2436 } else {
2437 target_size = 0;
2438 }
2439
2440 if (_cm->mark_stack_size() > target_size) {
2441 while (!has_aborted() && _cm->mark_stack_size() > target_size) {
2442 get_entries_from_global_stack();
2443 drain_local_queue(partially);
2444 }
2445 }
2446 }
2447
2448 // SATB Queue has several assumptions on whether to call the par or
2449 // non-par versions of the methods. this is why some of the code is
2450 // replicated. We should really get rid of the single-threaded version
2451 // of the code to simplify things.
2452 void G1CMTask::drain_satb_buffers() {
2453 if (has_aborted()) return;
2454
2455 // We set this so that the regular clock knows that we're in the
2456 // middle of draining buffers and doesn't set the abort flag when it
2457 // notices that SATB buffers are available for draining. It'd be
2458 // very counter productive if it did that. :-)
2459 _draining_satb_buffers = true;
2460
2461 G1CMSATBBufferClosure satb_cl(this, _g1h);
2462 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
2463
2464 // This keeps claiming and applying the closure to completed buffers
2465 // until we run out of buffers or we need to abort.
2466 while (!has_aborted() &&
2467 satb_mq_set.apply_closure_to_completed_buffer(&satb_cl)) {
2468 regular_clock_call();
2469 }
2470
2471 _draining_satb_buffers = false;
2472
2473 assert(has_aborted() ||
2474 concurrent() ||
2475 satb_mq_set.completed_buffers_num() == 0, "invariant");
2476
2477 // again, this was a potentially expensive operation, decrease the
2478 // limits to get the regular clock call early
2479 decrease_limits();
2480 }
2481
2482 void G1CMTask::print_stats() {
2483 log_debug(gc, stats)("Marking Stats, task = %u, calls = %d",
2484 _worker_id, _calls);
2485 log_debug(gc, stats)(" Elapsed time = %1.2lfms, Termination time = %1.2lfms",
2486 _elapsed_time_ms, _termination_time_ms);
2487 log_debug(gc, stats)(" Step Times (cum): num = %d, avg = %1.2lfms, sd = %1.2lfms",
2488 _step_times_ms.num(), _step_times_ms.avg(),
2489 _step_times_ms.sd());
2490 log_debug(gc, stats)(" max = %1.2lfms, total = %1.2lfms",
2491 _step_times_ms.maximum(), _step_times_ms.sum());
2492 }
2493
2494 bool G1ConcurrentMark::try_stealing(uint worker_id, int* hash_seed, oop& obj) {
2495 return _task_queues->steal(worker_id, hash_seed, obj);
2496 }
2497
2498 /*****************************************************************************
2499
2500 The do_marking_step(time_target_ms, ...) method is the building
2501 block of the parallel marking framework. It can be called in parallel
2502 with other invocations of do_marking_step() on different tasks
2503 (but only one per task, obviously) and concurrently with the
2504 mutator threads, or during remark, hence it eliminates the need
2505 for two versions of the code. When called during remark, it will
2506 pick up from where the task left off during the concurrent marking
2507 phase. Interestingly, tasks are also claimable during evacuation
2508 pauses too, since do_marking_step() ensures that it aborts before
2509 it needs to yield.
2510
2511 The data structures that it uses to do marking work are the
2512 following:
2513
2514 (1) Marking Bitmap. If there are gray objects that appear only
2515 on the bitmap (this happens either when dealing with an overflow
2516 or when the initial marking phase has simply marked the roots
2517 and didn't push them on the stack), then tasks claim heap
2518 regions whose bitmap they then scan to find gray objects. A
2519 global finger indicates where the end of the last claimed region
2520 is. A local finger indicates how far into the region a task has
2521 scanned. The two fingers are used to determine how to gray an
2522 object (i.e. whether simply marking it is OK, as it will be
2523 visited by a task in the future, or whether it needs to be also
2524 pushed on a stack).
2525
2526 (2) Local Queue. The local queue of the task which is accessed
2527 reasonably efficiently by the task. Other tasks can steal from
2528 it when they run out of work. Throughout the marking phase, a
2529 task attempts to keep its local queue short but not totally
2530 empty, so that entries are available for stealing by other
2531 tasks. Only when there is no more work, a task will totally
2532 drain its local queue.
2533
2534 (3) Global Mark Stack. This handles local queue overflow. During
2535 marking only sets of entries are moved between it and the local
2536 queues, as access to it requires a mutex and more fine-grain
2537 interaction with it which might cause contention. If it
2538 overflows, then the marking phase should restart and iterate
2539 over the bitmap to identify gray objects. Throughout the marking
2540 phase, tasks attempt to keep the global mark stack at a small
2541 length but not totally empty, so that entries are available for
2542 popping by other tasks. Only when there is no more work, tasks
2543 will totally drain the global mark stack.
2544
2545 (4) SATB Buffer Queue. This is where completed SATB buffers are
2546 made available. Buffers are regularly removed from this queue
2547 and scanned for roots, so that the queue doesn't get too
2548 long. During remark, all completed buffers are processed, as
2549 well as the filled in parts of any uncompleted buffers.
2550
2551 The do_marking_step() method tries to abort when the time target
2552 has been reached. There are a few other cases when the
2553 do_marking_step() method also aborts:
2554
2555 (1) When the marking phase has been aborted (after a Full GC).
2556
2557 (2) When a global overflow (on the global stack) has been
2558 triggered. Before the task aborts, it will actually sync up with
2559 the other tasks to ensure that all the marking data structures
2560 (local queues, stacks, fingers etc.) are re-initialized so that
2561 when do_marking_step() completes, the marking phase can
2562 immediately restart.
2563
2564 (3) When enough completed SATB buffers are available. The
2565 do_marking_step() method only tries to drain SATB buffers right
2566 at the beginning. So, if enough buffers are available, the
2567 marking step aborts and the SATB buffers are processed at
2568 the beginning of the next invocation.
2569
2570 (4) To yield. when we have to yield then we abort and yield
2571 right at the end of do_marking_step(). This saves us from a lot
2572 of hassle as, by yielding we might allow a Full GC. If this
2573 happens then objects will be compacted underneath our feet, the
2574 heap might shrink, etc. We save checking for this by just
2575 aborting and doing the yield right at the end.
2576
2577 From the above it follows that the do_marking_step() method should
2578 be called in a loop (or, otherwise, regularly) until it completes.
2579
2580 If a marking step completes without its has_aborted() flag being
2581 true, it means it has completed the current marking phase (and
2582 also all other marking tasks have done so and have all synced up).
2583
2584 A method called regular_clock_call() is invoked "regularly" (in
2585 sub ms intervals) throughout marking. It is this clock method that
2586 checks all the abort conditions which were mentioned above and
2587 decides when the task should abort. A work-based scheme is used to
2588 trigger this clock method: when the number of object words the
2589 marking phase has scanned or the number of references the marking
2590 phase has visited reach a given limit. Additional invocations to
2591 the method clock have been planted in a few other strategic places
2592 too. The initial reason for the clock method was to avoid calling
2593 vtime too regularly, as it is quite expensive. So, once it was in
2594 place, it was natural to piggy-back all the other conditions on it
2595 too and not constantly check them throughout the code.
2596
2597 If do_termination is true then do_marking_step will enter its
2598 termination protocol.
2599
2600 The value of is_serial must be true when do_marking_step is being
2601 called serially (i.e. by the VMThread) and do_marking_step should
2602 skip any synchronization in the termination and overflow code.
2603 Examples include the serial remark code and the serial reference
2604 processing closures.
2605
2606 The value of is_serial must be false when do_marking_step is
2607 being called by any of the worker threads in a work gang.
2608 Examples include the concurrent marking code (CMMarkingTask),
2609 the MT remark code, and the MT reference processing closures.
2610
2611 *****************************************************************************/
2612
2613 void G1CMTask::do_marking_step(double time_target_ms,
2614 bool do_termination,
2615 bool is_serial) {
2616 assert(time_target_ms >= 1.0, "minimum granularity is 1ms");
2617 assert(concurrent() == _cm->concurrent(), "they should be the same");
2618
2619 G1Policy* g1_policy = _g1h->g1_policy();
2620 assert(_task_queues != NULL, "invariant");
2621 assert(_task_queue != NULL, "invariant");
2622 assert(_task_queues->queue(_worker_id) == _task_queue, "invariant");
2623
2624 assert(!_claimed,
2625 "only one thread should claim this task at any one time");
2626
2627 // OK, this doesn't safeguard again all possible scenarios, as it is
2628 // possible for two threads to set the _claimed flag at the same
2629 // time. But it is only for debugging purposes anyway and it will
2630 // catch most problems.
2631 _claimed = true;
2632
2633 _start_time_ms = os::elapsedVTime() * 1000.0;
2634
2635 // If do_stealing is true then do_marking_step will attempt to
2636 // steal work from the other G1CMTasks. It only makes sense to
2637 // enable stealing when the termination protocol is enabled
2638 // and do_marking_step() is not being called serially.
2639 bool do_stealing = do_termination && !is_serial;
2640
2641 double diff_prediction_ms = _g1h->g1_policy()->predictor().get_new_prediction(&_marking_step_diffs_ms);
2642 _time_target_ms = time_target_ms - diff_prediction_ms;
2643
2644 // set up the variables that are used in the work-based scheme to
2645 // call the regular clock method
2646 _words_scanned = 0;
2647 _refs_reached = 0;
2648 recalculate_limits();
2649
2650 // clear all flags
2651 clear_has_aborted();
2652 _has_timed_out = false;
2653 _draining_satb_buffers = false;
2654
2655 ++_calls;
2656
2657 // Set up the bitmap and oop closures. Anything that uses them is
2658 // eventually called from this method, so it is OK to allocate these
2659 // statically.
2660 G1CMBitMapClosure bitmap_closure(this, _cm, _nextMarkBitMap);
2661 G1CMOopClosure cm_oop_closure(_g1h, _cm, this);
2662 set_cm_oop_closure(&cm_oop_closure);
2663
2664 if (_cm->has_overflown()) {
2665 // This can happen if the mark stack overflows during a GC pause
2666 // and this task, after a yield point, restarts. We have to abort
2667 // as we need to get into the overflow protocol which happens
2668 // right at the end of this task.
2669 set_has_aborted();
2670 }
2671
2672 // First drain any available SATB buffers. After this, we will not
2673 // look at SATB buffers before the next invocation of this method.
2674 // If enough completed SATB buffers are queued up, the regular clock
2675 // will abort this task so that it restarts.
2676 drain_satb_buffers();
2677 // ...then partially drain the local queue and the global stack
2678 drain_local_queue(true);
2679 drain_global_stack(true);
2680
2681 do {
2682 if (!has_aborted() && _curr_region != NULL) {
2683 // This means that we're already holding on to a region.
2684 assert(_finger != NULL, "if region is not NULL, then the finger "
2685 "should not be NULL either");
2686
2687 // We might have restarted this task after an evacuation pause
2688 // which might have evacuated the region we're holding on to
2689 // underneath our feet. Let's read its limit again to make sure
2690 // that we do not iterate over a region of the heap that
2691 // contains garbage (update_region_limit() will also move
2692 // _finger to the start of the region if it is found empty).
2693 update_region_limit();
2694 // We will start from _finger not from the start of the region,
2695 // as we might be restarting this task after aborting half-way
2696 // through scanning this region. In this case, _finger points to
2697 // the address where we last found a marked object. If this is a
2698 // fresh region, _finger points to start().
2699 MemRegion mr = MemRegion(_finger, _region_limit);
2700
2701 assert(!_curr_region->is_humongous() || mr.start() == _curr_region->bottom(),
2702 "humongous regions should go around loop once only");
2703
2704 // Some special cases:
2705 // If the memory region is empty, we can just give up the region.
2706 // If the current region is humongous then we only need to check
2707 // the bitmap for the bit associated with the start of the object,
2708 // scan the object if it's live, and give up the region.
2709 // Otherwise, let's iterate over the bitmap of the part of the region
2710 // that is left.
2711 // If the iteration is successful, give up the region.
2712 if (mr.is_empty()) {
2713 giveup_current_region();
2714 regular_clock_call();
2715 } else if (_curr_region->is_humongous() && mr.start() == _curr_region->bottom()) {
2716 if (_nextMarkBitMap->isMarked(mr.start())) {
2717 // The object is marked - apply the closure
2718 BitMap::idx_t offset = _nextMarkBitMap->heapWordToOffset(mr.start());
2719 bitmap_closure.do_bit(offset);
2720 }
2721 // Even if this task aborted while scanning the humongous object
2722 // we can (and should) give up the current region.
2723 giveup_current_region();
2724 regular_clock_call();
2725 } else if (_nextMarkBitMap->iterate(&bitmap_closure, mr)) {
2726 giveup_current_region();
2727 regular_clock_call();
2728 } else {
2729 assert(has_aborted(), "currently the only way to do so");
2730 // The only way to abort the bitmap iteration is to return
2731 // false from the do_bit() method. However, inside the
2732 // do_bit() method we move the _finger to point to the
2733 // object currently being looked at. So, if we bail out, we
2734 // have definitely set _finger to something non-null.
2735 assert(_finger != NULL, "invariant");
2736
2737 // Region iteration was actually aborted. So now _finger
2738 // points to the address of the object we last scanned. If we
2739 // leave it there, when we restart this task, we will rescan
2740 // the object. It is easy to avoid this. We move the finger by
2741 // enough to point to the next possible object header (the
2742 // bitmap knows by how much we need to move it as it knows its
2743 // granularity).
2744 assert(_finger < _region_limit, "invariant");
2745 HeapWord* new_finger = _nextMarkBitMap->nextObject(_finger);
2746 // Check if bitmap iteration was aborted while scanning the last object
2747 if (new_finger >= _region_limit) {
2748 giveup_current_region();
2749 } else {
2750 move_finger_to(new_finger);
2751 }
2752 }
2753 }
2754 // At this point we have either completed iterating over the
2755 // region we were holding on to, or we have aborted.
2756
2757 // We then partially drain the local queue and the global stack.
2758 // (Do we really need this?)
2759 drain_local_queue(true);
2760 drain_global_stack(true);
2761
2762 // Read the note on the claim_region() method on why it might
2763 // return NULL with potentially more regions available for
2764 // claiming and why we have to check out_of_regions() to determine
2765 // whether we're done or not.
2766 while (!has_aborted() && _curr_region == NULL && !_cm->out_of_regions()) {
2767 // We are going to try to claim a new region. We should have
2768 // given up on the previous one.
2769 // Separated the asserts so that we know which one fires.
2770 assert(_curr_region == NULL, "invariant");
2771 assert(_finger == NULL, "invariant");
2772 assert(_region_limit == NULL, "invariant");
2773 HeapRegion* claimed_region = _cm->claim_region(_worker_id);
2774 if (claimed_region != NULL) {
2775 // Yes, we managed to claim one
2776 setup_for_region(claimed_region);
2777 assert(_curr_region == claimed_region, "invariant");
2778 }
2779 // It is important to call the regular clock here. It might take
2780 // a while to claim a region if, for example, we hit a large
2781 // block of empty regions. So we need to call the regular clock
2782 // method once round the loop to make sure it's called
2783 // frequently enough.
2784 regular_clock_call();
2785 }
2786
2787 if (!has_aborted() && _curr_region == NULL) {
2788 assert(_cm->out_of_regions(),
2789 "at this point we should be out of regions");
2790 }
2791 } while ( _curr_region != NULL && !has_aborted());
2792
2793 if (!has_aborted()) {
2794 // We cannot check whether the global stack is empty, since other
2795 // tasks might be pushing objects to it concurrently.
2796 assert(_cm->out_of_regions(),
2797 "at this point we should be out of regions");
2798 // Try to reduce the number of available SATB buffers so that
2799 // remark has less work to do.
2800 drain_satb_buffers();
2801 }
2802
2803 // Since we've done everything else, we can now totally drain the
2804 // local queue and global stack.
2805 drain_local_queue(false);
2806 drain_global_stack(false);
2807
2808 // Attempt at work stealing from other task's queues.
2809 if (do_stealing && !has_aborted()) {
2810 // We have not aborted. This means that we have finished all that
2811 // we could. Let's try to do some stealing...
2812
2813 // We cannot check whether the global stack is empty, since other
2814 // tasks might be pushing objects to it concurrently.
2815 assert(_cm->out_of_regions() && _task_queue->size() == 0,
2816 "only way to reach here");
2817 while (!has_aborted()) {
2818 oop obj;
2819 if (_cm->try_stealing(_worker_id, &_hash_seed, obj)) {
2820 assert(_nextMarkBitMap->isMarked((HeapWord*) obj),
2821 "any stolen object should be marked");
2822 scan_object(obj);
2823
2824 // And since we're towards the end, let's totally drain the
2825 // local queue and global stack.
2826 drain_local_queue(false);
2827 drain_global_stack(false);
2828 } else {
2829 break;
2830 }
2831 }
2832 }
2833
2834 // We still haven't aborted. Now, let's try to get into the
2835 // termination protocol.
2836 if (do_termination && !has_aborted()) {
2837 // We cannot check whether the global stack is empty, since other
2838 // tasks might be concurrently pushing objects on it.
2839 // Separated the asserts so that we know which one fires.
2840 assert(_cm->out_of_regions(), "only way to reach here");
2841 assert(_task_queue->size() == 0, "only way to reach here");
2842 _termination_start_time_ms = os::elapsedVTime() * 1000.0;
2843
2844 // The G1CMTask class also extends the TerminatorTerminator class,
2845 // hence its should_exit_termination() method will also decide
2846 // whether to exit the termination protocol or not.
2847 bool finished = (is_serial ||
2848 _cm->terminator()->offer_termination(this));
2849 double termination_end_time_ms = os::elapsedVTime() * 1000.0;
2850 _termination_time_ms +=
2851 termination_end_time_ms - _termination_start_time_ms;
2852
2853 if (finished) {
2854 // We're all done.
2855
2856 if (_worker_id == 0) {
2857 // let's allow task 0 to do this
2858 if (concurrent()) {
2859 assert(_cm->concurrent_marking_in_progress(), "invariant");
2860 // we need to set this to false before the next
2861 // safepoint. This way we ensure that the marking phase
2862 // doesn't observe any more heap expansions.
2863 _cm->clear_concurrent_marking_in_progress();
2864 }
2865 }
2866
2867 // We can now guarantee that the global stack is empty, since
2868 // all other tasks have finished. We separated the guarantees so
2869 // that, if a condition is false, we can immediately find out
2870 // which one.
2871 guarantee(_cm->out_of_regions(), "only way to reach here");
2872 guarantee(_cm->mark_stack_empty(), "only way to reach here");
2873 guarantee(_task_queue->size() == 0, "only way to reach here");
2874 guarantee(!_cm->has_overflown(), "only way to reach here");
2875 guarantee(!_cm->mark_stack_overflow(), "only way to reach here");
2876 } else {
2877 // Apparently there's more work to do. Let's abort this task. It
2878 // will restart it and we can hopefully find more things to do.
2879 set_has_aborted();
2880 }
2881 }
2882
2883 // Mainly for debugging purposes to make sure that a pointer to the
2884 // closure which was statically allocated in this frame doesn't
2885 // escape it by accident.
2886 set_cm_oop_closure(NULL);
2887 double end_time_ms = os::elapsedVTime() * 1000.0;
2888 double elapsed_time_ms = end_time_ms - _start_time_ms;
2889 // Update the step history.
2890 _step_times_ms.add(elapsed_time_ms);
2891
2892 if (has_aborted()) {
2893 // The task was aborted for some reason.
2894 if (_has_timed_out) {
2895 double diff_ms = elapsed_time_ms - _time_target_ms;
2896 // Keep statistics of how well we did with respect to hitting
2897 // our target only if we actually timed out (if we aborted for
2898 // other reasons, then the results might get skewed).
2899 _marking_step_diffs_ms.add(diff_ms);
2900 }
2901
2902 if (_cm->has_overflown()) {
2903 // This is the interesting one. We aborted because a global
2904 // overflow was raised. This means we have to restart the
2905 // marking phase and start iterating over regions. However, in
2906 // order to do this we have to make sure that all tasks stop
2907 // what they are doing and re-initialize in a safe manner. We
2908 // will achieve this with the use of two barrier sync points.
2909
2910 if (!is_serial) {
2911 // We only need to enter the sync barrier if being called
2912 // from a parallel context
2913 _cm->enter_first_sync_barrier(_worker_id);
2914
2915 // When we exit this sync barrier we know that all tasks have
2916 // stopped doing marking work. So, it's now safe to
2917 // re-initialize our data structures. At the end of this method,
2918 // task 0 will clear the global data structures.
2919 }
2920
2921 // We clear the local state of this task...
2922 clear_region_fields();
2923
2924 if (!is_serial) {
2925 // ...and enter the second barrier.
2926 _cm->enter_second_sync_barrier(_worker_id);
2927 }
2928 // At this point, if we're during the concurrent phase of
2929 // marking, everything has been re-initialized and we're
2930 // ready to restart.
2931 }
2932 }
2933
2934 _claimed = false;
2935 }
2936
2937 G1CMTask::G1CMTask(uint worker_id,
2938 G1ConcurrentMark* cm,
2939 G1CMTaskQueue* task_queue,
2940 G1CMTaskQueueSet* task_queues)
2941 : _g1h(G1CollectedHeap::heap()),
2942 _worker_id(worker_id), _cm(cm),
2943 _claimed(false),
2944 _nextMarkBitMap(NULL), _hash_seed(17),
2945 _task_queue(task_queue),
2946 _task_queues(task_queues),
2947 _cm_oop_closure(NULL) {
2948 guarantee(task_queue != NULL, "invariant");
2949 guarantee(task_queues != NULL, "invariant");
2950
2951 _marking_step_diffs_ms.add(0.5);
2952 }
2953
2954 // These are formatting macros that are used below to ensure
2955 // consistent formatting. The *_H_* versions are used to format the
2956 // header for a particular value and they should be kept consistent
2957 // with the corresponding macro. Also note that most of the macros add
2958 // the necessary white space (as a prefix) which makes them a bit
2959 // easier to compose.
2960
2961 // All the output lines are prefixed with this string to be able to
2962 // identify them easily in a large log file.
2963 #define G1PPRL_LINE_PREFIX "###"
2964
2965 #define G1PPRL_ADDR_BASE_FORMAT " " PTR_FORMAT "-" PTR_FORMAT
2966 #ifdef _LP64
2967 #define G1PPRL_ADDR_BASE_H_FORMAT " %37s"
2968 #else // _LP64
2969 #define G1PPRL_ADDR_BASE_H_FORMAT " %21s"
2970 #endif // _LP64
2971
2972 // For per-region info
2973 #define G1PPRL_TYPE_FORMAT " %-4s"
2974 #define G1PPRL_TYPE_H_FORMAT " %4s"
2975 #define G1PPRL_BYTE_FORMAT " " SIZE_FORMAT_W(9)
2976 #define G1PPRL_BYTE_H_FORMAT " %9s"
2977 #define G1PPRL_DOUBLE_FORMAT " %14.1f"
2978 #define G1PPRL_DOUBLE_H_FORMAT " %14s"
2979
2980 // For summary info
2981 #define G1PPRL_SUM_ADDR_FORMAT(tag) " " tag ":" G1PPRL_ADDR_BASE_FORMAT
2982 #define G1PPRL_SUM_BYTE_FORMAT(tag) " " tag ": " SIZE_FORMAT
2983 #define G1PPRL_SUM_MB_FORMAT(tag) " " tag ": %1.2f MB"
2984 #define G1PPRL_SUM_MB_PERC_FORMAT(tag) G1PPRL_SUM_MB_FORMAT(tag) " / %1.2f %%"
2985
2986 G1PrintRegionLivenessInfoClosure::
2987 G1PrintRegionLivenessInfoClosure(const char* phase_name)
2988 : _total_used_bytes(0), _total_capacity_bytes(0),
2989 _total_prev_live_bytes(0), _total_next_live_bytes(0),
2990 _total_remset_bytes(0), _total_strong_code_roots_bytes(0) {
2991 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2992 MemRegion g1_reserved = g1h->g1_reserved();
2993 double now = os::elapsedTime();
2994
2995 // Print the header of the output.
2996 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX" PHASE %s @ %1.3f", phase_name, now);
2997 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX" HEAP"
2998 G1PPRL_SUM_ADDR_FORMAT("reserved")
2999 G1PPRL_SUM_BYTE_FORMAT("region-size"),
3000 p2i(g1_reserved.start()), p2i(g1_reserved.end()),
3001 HeapRegion::GrainBytes);
3002 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX);
3003 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX
3004 G1PPRL_TYPE_H_FORMAT
3005 G1PPRL_ADDR_BASE_H_FORMAT
3006 G1PPRL_BYTE_H_FORMAT
3007 G1PPRL_BYTE_H_FORMAT
3008 G1PPRL_BYTE_H_FORMAT
3009 G1PPRL_DOUBLE_H_FORMAT
3010 G1PPRL_BYTE_H_FORMAT
3011 G1PPRL_BYTE_H_FORMAT,
3012 "type", "address-range",
3013 "used", "prev-live", "next-live", "gc-eff",
3014 "remset", "code-roots");
3015 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX
3016 G1PPRL_TYPE_H_FORMAT
3017 G1PPRL_ADDR_BASE_H_FORMAT
3018 G1PPRL_BYTE_H_FORMAT
3019 G1PPRL_BYTE_H_FORMAT
3020 G1PPRL_BYTE_H_FORMAT
3021 G1PPRL_DOUBLE_H_FORMAT
3022 G1PPRL_BYTE_H_FORMAT
3023 G1PPRL_BYTE_H_FORMAT,
3024 "", "",
3025 "(bytes)", "(bytes)", "(bytes)", "(bytes/ms)",
3026 "(bytes)", "(bytes)");
3027 }
3028
3029 bool G1PrintRegionLivenessInfoClosure::doHeapRegion(HeapRegion* r) {
3030 const char* type = r->get_type_str();
3031 HeapWord* bottom = r->bottom();
3032 HeapWord* end = r->end();
3033 size_t capacity_bytes = r->capacity();
3034 size_t used_bytes = r->used();
3035 size_t prev_live_bytes = r->live_bytes();
3036 size_t next_live_bytes = r->next_live_bytes();
3037 double gc_eff = r->gc_efficiency();
3038 size_t remset_bytes = r->rem_set()->mem_size();
3039 size_t strong_code_roots_bytes = r->rem_set()->strong_code_roots_mem_size();
3040
3041 _total_used_bytes += used_bytes;
3042 _total_capacity_bytes += capacity_bytes;
3043 _total_prev_live_bytes += prev_live_bytes;
3044 _total_next_live_bytes += next_live_bytes;
3045 _total_remset_bytes += remset_bytes;
3046 _total_strong_code_roots_bytes += strong_code_roots_bytes;
3047
3048 // Print a line for this particular region.
3049 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX
3050 G1PPRL_TYPE_FORMAT
3051 G1PPRL_ADDR_BASE_FORMAT
3052 G1PPRL_BYTE_FORMAT
3053 G1PPRL_BYTE_FORMAT
3054 G1PPRL_BYTE_FORMAT
3055 G1PPRL_DOUBLE_FORMAT
3056 G1PPRL_BYTE_FORMAT
3057 G1PPRL_BYTE_FORMAT,
3058 type, p2i(bottom), p2i(end),
3059 used_bytes, prev_live_bytes, next_live_bytes, gc_eff,
3060 remset_bytes, strong_code_roots_bytes);
3061
3062 return false;
3063 }
3064
3065 G1PrintRegionLivenessInfoClosure::~G1PrintRegionLivenessInfoClosure() {
3066 // add static memory usages to remembered set sizes
3067 _total_remset_bytes += HeapRegionRemSet::fl_mem_size() + HeapRegionRemSet::static_mem_size();
3068 // Print the footer of the output.
3069 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX);
3070 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX
3071 " SUMMARY"
3072 G1PPRL_SUM_MB_FORMAT("capacity")
3073 G1PPRL_SUM_MB_PERC_FORMAT("used")
3074 G1PPRL_SUM_MB_PERC_FORMAT("prev-live")
3075 G1PPRL_SUM_MB_PERC_FORMAT("next-live")
3076 G1PPRL_SUM_MB_FORMAT("remset")
3077 G1PPRL_SUM_MB_FORMAT("code-roots"),
3078 bytes_to_mb(_total_capacity_bytes),
3079 bytes_to_mb(_total_used_bytes),
3080 perc(_total_used_bytes, _total_capacity_bytes),
3081 bytes_to_mb(_total_prev_live_bytes),
3082 perc(_total_prev_live_bytes, _total_capacity_bytes),
3083 bytes_to_mb(_total_next_live_bytes),
3084 perc(_total_next_live_bytes, _total_capacity_bytes),
3085 bytes_to_mb(_total_remset_bytes),
3086 bytes_to_mb(_total_strong_code_roots_bytes));
3087 }