1 /*
2 * Copyright (c) 2001, 2017, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/metadataOnStackMark.hpp"
27 #include "classfile/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/align.hpp"
61 #include "utilities/growableArray.hpp"
62
63 void G1CMBitMap::print_on_error(outputStream* st, const char* prefix) const {
64 _bm.print_on_error(st, prefix);
65 }
66
67 size_t G1CMBitMap::compute_size(size_t heap_size) {
68 return ReservedSpace::allocation_align_size_up(heap_size / mark_distance());
69 }
70
71 size_t G1CMBitMap::mark_distance() {
72 return MinObjAlignmentInBytes * BitsPerByte;
73 }
74
75 void G1CMBitMap::initialize(MemRegion heap, G1RegionToSpaceMapper* storage) {
76 _covered = heap;
77
78 _bm = BitMapView((BitMap::bm_word_t*) storage->reserved().start(), _covered.word_size() >> _shifter);
79
80 storage->set_mapping_changed_listener(&_listener);
81 }
82
83 void G1CMBitMapMappingChangedListener::on_commit(uint start_region, size_t num_regions, bool zero_filled) {
84 if (zero_filled) {
85 return;
86 }
87 // We need to clear the bitmap on commit, removing any existing information.
88 MemRegion mr(G1CollectedHeap::heap()->bottom_addr_for_region(start_region), num_regions * HeapRegion::GrainWords);
89 _bm->clear_range(mr);
90 }
91
92 void G1CMBitMap::clear_range(MemRegion mr) {
93 MemRegion intersection = mr.intersection(_covered);
94 assert(!intersection.is_empty(),
95 "Given range from " PTR_FORMAT " to " PTR_FORMAT " is completely outside the heap",
96 p2i(mr.start()), p2i(mr.end()));
97 // convert address range into offset range
98 _bm.at_put_range(addr_to_offset(intersection.start()),
99 addr_to_offset(intersection.end()), false);
100 }
101
102 G1CMMarkStack::G1CMMarkStack() :
103 _max_chunk_capacity(0),
104 _base(NULL),
105 _chunk_capacity(0) {
106 set_empty();
107 }
108
109 bool G1CMMarkStack::resize(size_t new_capacity) {
110 assert(is_empty(), "Only resize when stack is empty.");
111 assert(new_capacity <= _max_chunk_capacity,
112 "Trying to resize stack to " SIZE_FORMAT " chunks when the maximum is " SIZE_FORMAT, new_capacity, _max_chunk_capacity);
113
114 TaskQueueEntryChunk* new_base = MmapArrayAllocator<TaskQueueEntryChunk, mtGC>::allocate_or_null(new_capacity);
115
116 if (new_base == NULL) {
117 log_warning(gc)("Failed to reserve memory for new overflow mark stack with " SIZE_FORMAT " chunks and size " SIZE_FORMAT "B.", new_capacity, new_capacity * sizeof(TaskQueueEntryChunk));
118 return false;
119 }
120 // Release old mapping.
121 if (_base != NULL) {
122 MmapArrayAllocator<TaskQueueEntryChunk, mtGC>::free(_base, _chunk_capacity);
123 }
124
125 _base = new_base;
126 _chunk_capacity = new_capacity;
127 set_empty();
128
129 return true;
130 }
131
132 size_t G1CMMarkStack::capacity_alignment() {
133 return (size_t)lcm(os::vm_allocation_granularity(), sizeof(TaskQueueEntryChunk)) / sizeof(G1TaskQueueEntry);
134 }
135
136 bool G1CMMarkStack::initialize(size_t initial_capacity, size_t max_capacity) {
137 guarantee(_max_chunk_capacity == 0, "G1CMMarkStack already initialized.");
138
139 size_t const TaskEntryChunkSizeInVoidStar = sizeof(TaskQueueEntryChunk) / sizeof(G1TaskQueueEntry);
140
141 _max_chunk_capacity = align_up(max_capacity, capacity_alignment()) / TaskEntryChunkSizeInVoidStar;
142 size_t initial_chunk_capacity = align_up(initial_capacity, capacity_alignment()) / TaskEntryChunkSizeInVoidStar;
143
144 guarantee(initial_chunk_capacity <= _max_chunk_capacity,
145 "Maximum chunk capacity " SIZE_FORMAT " smaller than initial capacity " SIZE_FORMAT,
146 _max_chunk_capacity,
147 initial_chunk_capacity);
148
149 log_debug(gc)("Initialize mark stack with " SIZE_FORMAT " chunks, maximum " SIZE_FORMAT,
150 initial_chunk_capacity, _max_chunk_capacity);
151
152 return resize(initial_chunk_capacity);
153 }
154
155 void G1CMMarkStack::expand() {
156 if (_chunk_capacity == _max_chunk_capacity) {
157 log_debug(gc)("Can not expand overflow mark stack further, already at maximum capacity of " SIZE_FORMAT " chunks.", _chunk_capacity);
158 return;
159 }
160 size_t old_capacity = _chunk_capacity;
161 // Double capacity if possible
162 size_t new_capacity = MIN2(old_capacity * 2, _max_chunk_capacity);
163
164 if (resize(new_capacity)) {
165 log_debug(gc)("Expanded mark stack capacity from " SIZE_FORMAT " to " SIZE_FORMAT " chunks",
166 old_capacity, new_capacity);
167 } else {
168 log_warning(gc)("Failed to expand mark stack capacity from " SIZE_FORMAT " to " SIZE_FORMAT " chunks",
169 old_capacity, new_capacity);
170 }
171 }
172
173 G1CMMarkStack::~G1CMMarkStack() {
174 if (_base != NULL) {
175 MmapArrayAllocator<TaskQueueEntryChunk, mtGC>::free(_base, _chunk_capacity);
176 }
177 }
178
179 void G1CMMarkStack::add_chunk_to_list(TaskQueueEntryChunk* volatile* list, TaskQueueEntryChunk* elem) {
180 elem->next = *list;
181 *list = elem;
182 }
183
184 void G1CMMarkStack::add_chunk_to_chunk_list(TaskQueueEntryChunk* elem) {
185 MutexLockerEx x(MarkStackChunkList_lock, Mutex::_no_safepoint_check_flag);
186 add_chunk_to_list(&_chunk_list, elem);
187 _chunks_in_chunk_list++;
188 }
189
190 void G1CMMarkStack::add_chunk_to_free_list(TaskQueueEntryChunk* elem) {
191 MutexLockerEx x(MarkStackFreeList_lock, Mutex::_no_safepoint_check_flag);
192 add_chunk_to_list(&_free_list, elem);
193 }
194
195 G1CMMarkStack::TaskQueueEntryChunk* G1CMMarkStack::remove_chunk_from_list(TaskQueueEntryChunk* volatile* list) {
196 TaskQueueEntryChunk* result = *list;
197 if (result != NULL) {
198 *list = (*list)->next;
199 }
200 return result;
201 }
202
203 G1CMMarkStack::TaskQueueEntryChunk* G1CMMarkStack::remove_chunk_from_chunk_list() {
204 MutexLockerEx x(MarkStackChunkList_lock, Mutex::_no_safepoint_check_flag);
205 TaskQueueEntryChunk* result = remove_chunk_from_list(&_chunk_list);
206 if (result != NULL) {
207 _chunks_in_chunk_list--;
208 }
209 return result;
210 }
211
212 G1CMMarkStack::TaskQueueEntryChunk* G1CMMarkStack::remove_chunk_from_free_list() {
213 MutexLockerEx x(MarkStackFreeList_lock, Mutex::_no_safepoint_check_flag);
214 return remove_chunk_from_list(&_free_list);
215 }
216
217 G1CMMarkStack::TaskQueueEntryChunk* G1CMMarkStack::allocate_new_chunk() {
218 // This dirty read of _hwm is okay because we only ever increase the _hwm in parallel code.
219 // Further this limits _hwm to a value of _chunk_capacity + #threads, avoiding
220 // wraparound of _hwm.
221 if (_hwm >= _chunk_capacity) {
222 return NULL;
223 }
224
225 size_t cur_idx = Atomic::add(1, &_hwm) - 1;
226 if (cur_idx >= _chunk_capacity) {
227 return NULL;
228 }
229
230 TaskQueueEntryChunk* result = ::new (&_base[cur_idx]) TaskQueueEntryChunk;
231 result->next = NULL;
232 return result;
233 }
234
235 bool G1CMMarkStack::par_push_chunk(G1TaskQueueEntry* ptr_arr) {
236 // Get a new chunk.
237 TaskQueueEntryChunk* new_chunk = remove_chunk_from_free_list();
238
239 if (new_chunk == NULL) {
240 // Did not get a chunk from the free list. Allocate from backing memory.
241 new_chunk = allocate_new_chunk();
242
243 if (new_chunk == NULL) {
244 return false;
245 }
246 }
247
248 Copy::conjoint_memory_atomic(ptr_arr, new_chunk->data, EntriesPerChunk * sizeof(G1TaskQueueEntry));
249
250 add_chunk_to_chunk_list(new_chunk);
251
252 return true;
253 }
254
255 bool G1CMMarkStack::par_pop_chunk(G1TaskQueueEntry* ptr_arr) {
256 TaskQueueEntryChunk* cur = remove_chunk_from_chunk_list();
257
258 if (cur == NULL) {
259 return false;
260 }
261
262 Copy::conjoint_memory_atomic(cur->data, ptr_arr, EntriesPerChunk * sizeof(G1TaskQueueEntry));
263
264 add_chunk_to_free_list(cur);
265 return true;
266 }
267
268 void G1CMMarkStack::set_empty() {
269 _chunks_in_chunk_list = 0;
270 _hwm = 0;
271 _chunk_list = NULL;
272 _free_list = NULL;
273 }
274
275 G1CMRootRegions::G1CMRootRegions() :
276 _cm(NULL), _scan_in_progress(false),
277 _should_abort(false), _claimed_survivor_index(0) { }
278
279 void G1CMRootRegions::init(const G1SurvivorRegions* survivors, G1ConcurrentMark* cm) {
280 _survivors = survivors;
281 _cm = cm;
282 }
283
284 void G1CMRootRegions::prepare_for_scan() {
285 assert(!scan_in_progress(), "pre-condition");
286
287 // Currently, only survivors can be root regions.
288 _claimed_survivor_index = 0;
289 _scan_in_progress = _survivors->regions()->is_nonempty();
290 _should_abort = false;
291 }
292
293 HeapRegion* G1CMRootRegions::claim_next() {
294 if (_should_abort) {
295 // If someone has set the should_abort flag, we return NULL to
296 // force the caller to bail out of their loop.
297 return NULL;
298 }
299
300 // Currently, only survivors can be root regions.
301 const GrowableArray<HeapRegion*>* survivor_regions = _survivors->regions();
302
303 int claimed_index = Atomic::add(1, &_claimed_survivor_index) - 1;
304 if (claimed_index < survivor_regions->length()) {
305 return survivor_regions->at(claimed_index);
306 }
307 return NULL;
308 }
309
310 uint G1CMRootRegions::num_root_regions() const {
311 return (uint)_survivors->regions()->length();
312 }
313
314 void G1CMRootRegions::notify_scan_done() {
315 MutexLockerEx x(RootRegionScan_lock, Mutex::_no_safepoint_check_flag);
316 _scan_in_progress = false;
317 RootRegionScan_lock->notify_all();
318 }
319
320 void G1CMRootRegions::cancel_scan() {
321 notify_scan_done();
322 }
323
324 void G1CMRootRegions::scan_finished() {
325 assert(scan_in_progress(), "pre-condition");
326
327 // Currently, only survivors can be root regions.
328 if (!_should_abort) {
329 assert(_claimed_survivor_index >= 0, "otherwise comparison is invalid: %d", _claimed_survivor_index);
330 assert((uint)_claimed_survivor_index >= _survivors->length(),
331 "we should have claimed all survivors, claimed index = %u, length = %u",
332 (uint)_claimed_survivor_index, _survivors->length());
333 }
334
335 notify_scan_done();
336 }
337
338 bool G1CMRootRegions::wait_until_scan_finished() {
339 if (!scan_in_progress()) return false;
340
341 {
342 MutexLockerEx x(RootRegionScan_lock, Mutex::_no_safepoint_check_flag);
343 while (scan_in_progress()) {
344 RootRegionScan_lock->wait(Mutex::_no_safepoint_check_flag);
345 }
346 }
347 return true;
348 }
349
350 uint G1ConcurrentMark::scale_parallel_threads(uint n_par_threads) {
351 return MAX2((n_par_threads + 2) / 4, 1U);
352 }
353
354 G1ConcurrentMark::G1ConcurrentMark(G1CollectedHeap* g1h, G1RegionToSpaceMapper* prev_bitmap_storage, G1RegionToSpaceMapper* next_bitmap_storage) :
355 _g1h(g1h),
356 _markBitMap1(),
357 _markBitMap2(),
358 _parallel_marking_threads(0),
359 _max_parallel_marking_threads(0),
360 _sleep_factor(0.0),
361 _marking_task_overhead(1.0),
362 _cleanup_list("Cleanup List"),
363
364 _prevMarkBitMap(&_markBitMap1),
365 _nextMarkBitMap(&_markBitMap2),
366
367 _global_mark_stack(),
368 // _finger set in set_non_marking_state
369
370 _max_worker_id(ParallelGCThreads),
371 // _active_tasks set in set_non_marking_state
372 // _tasks set inside the constructor
373 _task_queues(new G1CMTaskQueueSet((int) _max_worker_id)),
374 _terminator(ParallelTaskTerminator((int) _max_worker_id, _task_queues)),
375
376 _has_overflown(false),
377 _concurrent(false),
378 _has_aborted(false),
379 _restart_for_overflow(false),
380 _concurrent_marking_in_progress(false),
381 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
382 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()),
383
384 // _verbose_level set below
385
386 _init_times(),
387 _remark_times(), _remark_mark_times(), _remark_weak_ref_times(),
388 _cleanup_times(),
389 _total_counting_time(0.0),
390 _total_rs_scrub_time(0.0),
391
392 _parallel_workers(NULL),
393
394 _completed_initialization(false) {
395
396 _markBitMap1.initialize(g1h->reserved_region(), prev_bitmap_storage);
397 _markBitMap2.initialize(g1h->reserved_region(), next_bitmap_storage);
398
399 // Create & start a ConcurrentMark thread.
400 _cmThread = new ConcurrentMarkThread(this);
401 assert(cmThread() != NULL, "CM Thread should have been created");
402 assert(cmThread()->cm() != NULL, "CM Thread should refer to this cm");
403 if (_cmThread->osthread() == NULL) {
404 vm_shutdown_during_initialization("Could not create ConcurrentMarkThread");
405 }
406
407 assert(CGC_lock != NULL, "Where's the CGC_lock?");
408
409 SATBMarkQueueSet& satb_qs = JavaThread::satb_mark_queue_set();
410 satb_qs.set_buffer_size(G1SATBBufferSize);
411
412 _root_regions.init(_g1h->survivor(), this);
413
414 if (ConcGCThreads > ParallelGCThreads) {
415 log_warning(gc)("Can't have more ConcGCThreads (%u) than ParallelGCThreads (%u).",
416 ConcGCThreads, ParallelGCThreads);
417 return;
418 }
419 if (!FLAG_IS_DEFAULT(ConcGCThreads) && ConcGCThreads > 0) {
420 // Note: ConcGCThreads has precedence over G1MarkingOverheadPercent
421 // if both are set
422 _sleep_factor = 0.0;
423 _marking_task_overhead = 1.0;
424 } else if (G1MarkingOverheadPercent > 0) {
425 // We will calculate the number of parallel marking threads based
426 // on a target overhead with respect to the soft real-time goal
427 double marking_overhead = (double) G1MarkingOverheadPercent / 100.0;
428 double overall_cm_overhead =
429 (double) MaxGCPauseMillis * marking_overhead /
430 (double) GCPauseIntervalMillis;
431 double cpu_ratio = 1.0 / os::initial_active_processor_count();
432 double marking_thread_num = ceil(overall_cm_overhead / cpu_ratio);
433 double marking_task_overhead =
434 overall_cm_overhead / marking_thread_num * os::initial_active_processor_count();
435 double sleep_factor =
436 (1.0 - marking_task_overhead) / marking_task_overhead;
437
438 FLAG_SET_ERGO(uint, ConcGCThreads, (uint) marking_thread_num);
439 _sleep_factor = sleep_factor;
440 _marking_task_overhead = marking_task_overhead;
441 } else {
442 // Calculate the number of parallel marking threads by scaling
443 // the number of parallel GC threads.
444 uint marking_thread_num = scale_parallel_threads(ParallelGCThreads);
445 FLAG_SET_ERGO(uint, ConcGCThreads, marking_thread_num);
446 _sleep_factor = 0.0;
447 _marking_task_overhead = 1.0;
448 }
449
450 assert(ConcGCThreads > 0, "Should have been set");
451 log_debug(gc)("ConcGCThreads: %u", ConcGCThreads);
452 log_debug(gc)("ParallelGCThreads: %u", ParallelGCThreads);
453 _parallel_marking_threads = ConcGCThreads;
454 _max_parallel_marking_threads = _parallel_marking_threads;
455
456 _parallel_workers = new WorkGang("G1 Marker",
457 _max_parallel_marking_threads, false, true);
458 if (_parallel_workers == NULL) {
459 vm_exit_during_initialization("Failed necessary allocation.");
460 } else {
461 _parallel_workers->initialize_workers();
462 }
463
464 if (FLAG_IS_DEFAULT(MarkStackSize)) {
465 size_t mark_stack_size =
466 MIN2(MarkStackSizeMax,
467 MAX2(MarkStackSize, (size_t) (parallel_marking_threads() * TASKQUEUE_SIZE)));
468 // Verify that the calculated value for MarkStackSize is in range.
469 // It would be nice to use the private utility routine from Arguments.
470 if (!(mark_stack_size >= 1 && mark_stack_size <= MarkStackSizeMax)) {
471 log_warning(gc)("Invalid value calculated for MarkStackSize (" SIZE_FORMAT "): "
472 "must be between 1 and " SIZE_FORMAT,
473 mark_stack_size, MarkStackSizeMax);
474 return;
475 }
476 FLAG_SET_ERGO(size_t, MarkStackSize, mark_stack_size);
477 } else {
478 // Verify MarkStackSize is in range.
479 if (FLAG_IS_CMDLINE(MarkStackSize)) {
480 if (FLAG_IS_DEFAULT(MarkStackSizeMax)) {
481 if (!(MarkStackSize >= 1 && MarkStackSize <= MarkStackSizeMax)) {
482 log_warning(gc)("Invalid value specified for MarkStackSize (" SIZE_FORMAT "): "
483 "must be between 1 and " SIZE_FORMAT,
484 MarkStackSize, MarkStackSizeMax);
485 return;
486 }
487 } else if (FLAG_IS_CMDLINE(MarkStackSizeMax)) {
488 if (!(MarkStackSize >= 1 && MarkStackSize <= MarkStackSizeMax)) {
489 log_warning(gc)("Invalid value specified for MarkStackSize (" SIZE_FORMAT ")"
490 " or for MarkStackSizeMax (" SIZE_FORMAT ")",
491 MarkStackSize, MarkStackSizeMax);
492 return;
493 }
494 }
495 }
496 }
497
498 if (!_global_mark_stack.initialize(MarkStackSize, MarkStackSizeMax)) {
499 vm_exit_during_initialization("Failed to allocate initial concurrent mark overflow mark stack.");
500 }
501
502 _tasks = NEW_C_HEAP_ARRAY(G1CMTask*, _max_worker_id, mtGC);
503 _accum_task_vtime = NEW_C_HEAP_ARRAY(double, _max_worker_id, mtGC);
504
505 // so that the assertion in MarkingTaskQueue::task_queue doesn't fail
506 _active_tasks = _max_worker_id;
507
508 for (uint i = 0; i < _max_worker_id; ++i) {
509 G1CMTaskQueue* task_queue = new G1CMTaskQueue();
510 task_queue->initialize();
511 _task_queues->register_queue(i, task_queue);
512
513 _tasks[i] = new G1CMTask(i, this, task_queue, _task_queues);
514
515 _accum_task_vtime[i] = 0.0;
516 }
517
518 // so that the call below can read a sensible value
519 _heap_start = g1h->reserved_region().start();
520 set_non_marking_state();
521 _completed_initialization = true;
522 }
523
524 void G1ConcurrentMark::reset() {
525 // Starting values for these two. This should be called in a STW
526 // phase.
527 MemRegion reserved = _g1h->g1_reserved();
528 _heap_start = reserved.start();
529 _heap_end = reserved.end();
530
531 // Separated the asserts so that we know which one fires.
532 assert(_heap_start != NULL, "heap bounds should look ok");
533 assert(_heap_end != NULL, "heap bounds should look ok");
534 assert(_heap_start < _heap_end, "heap bounds should look ok");
535
536 // Reset all the marking data structures and any necessary flags
537 reset_marking_state();
538
539 // We do reset all of them, since different phases will use
540 // different number of active threads. So, it's easiest to have all
541 // of them ready.
542 for (uint i = 0; i < _max_worker_id; ++i) {
543 _tasks[i]->reset(_nextMarkBitMap);
544 }
545
546 // we need this to make sure that the flag is on during the evac
547 // pause with initial mark piggy-backed
548 set_concurrent_marking_in_progress();
549 }
550
551
552 void G1ConcurrentMark::reset_marking_state() {
553 _global_mark_stack.set_empty();
554
555 // Expand the marking stack, if we have to and if we can.
556 if (has_overflown()) {
557 _global_mark_stack.expand();
558 }
559
560 clear_has_overflown();
561 _finger = _heap_start;
562
563 for (uint i = 0; i < _max_worker_id; ++i) {
564 G1CMTaskQueue* queue = _task_queues->queue(i);
565 queue->set_empty();
566 }
567 }
568
569 void G1ConcurrentMark::set_concurrency(uint active_tasks) {
570 assert(active_tasks <= _max_worker_id, "we should not have more");
571
572 _active_tasks = active_tasks;
573 // Need to update the three data structures below according to the
574 // number of active threads for this phase.
575 _terminator = ParallelTaskTerminator((int) active_tasks, _task_queues);
576 _first_overflow_barrier_sync.set_n_workers((int) active_tasks);
577 _second_overflow_barrier_sync.set_n_workers((int) active_tasks);
578 }
579
580 void G1ConcurrentMark::set_concurrency_and_phase(uint active_tasks, bool concurrent) {
581 set_concurrency(active_tasks);
582
583 _concurrent = concurrent;
584 // We propagate this to all tasks, not just the active ones.
585 for (uint i = 0; i < _max_worker_id; ++i)
586 _tasks[i]->set_concurrent(concurrent);
587
588 if (concurrent) {
589 set_concurrent_marking_in_progress();
590 } else {
591 // We currently assume that the concurrent flag has been set to
592 // false before we start remark. At this point we should also be
593 // in a STW phase.
594 assert(!concurrent_marking_in_progress(), "invariant");
595 assert(out_of_regions(),
596 "only way to get here: _finger: " PTR_FORMAT ", _heap_end: " PTR_FORMAT,
597 p2i(_finger), p2i(_heap_end));
598 }
599 }
600
601 void G1ConcurrentMark::set_non_marking_state() {
602 // We set the global marking state to some default values when we're
603 // not doing marking.
604 reset_marking_state();
605 _active_tasks = 0;
606 clear_concurrent_marking_in_progress();
607 }
608
609 G1ConcurrentMark::~G1ConcurrentMark() {
610 // The G1ConcurrentMark instance is never freed.
611 ShouldNotReachHere();
612 }
613
614 class G1ClearBitMapTask : public AbstractGangTask {
615 public:
616 static size_t chunk_size() { return M; }
617
618 private:
619 // Heap region closure used for clearing the given mark bitmap.
620 class G1ClearBitmapHRClosure : public HeapRegionClosure {
621 private:
622 G1CMBitMap* _bitmap;
623 G1ConcurrentMark* _cm;
624 public:
625 G1ClearBitmapHRClosure(G1CMBitMap* bitmap, G1ConcurrentMark* cm) : HeapRegionClosure(), _cm(cm), _bitmap(bitmap) {
626 }
627
628 virtual bool doHeapRegion(HeapRegion* r) {
629 size_t const chunk_size_in_words = G1ClearBitMapTask::chunk_size() / HeapWordSize;
630
631 HeapWord* cur = r->bottom();
632 HeapWord* const end = r->end();
633
634 while (cur < end) {
635 MemRegion mr(cur, MIN2(cur + chunk_size_in_words, end));
636 _bitmap->clear_range(mr);
637
638 cur += chunk_size_in_words;
639
640 // Abort iteration if after yielding the marking has been aborted.
641 if (_cm != NULL && _cm->do_yield_check() && _cm->has_aborted()) {
642 return true;
643 }
644 // Repeat the asserts from before the start of the closure. We will do them
645 // as asserts here to minimize their overhead on the product. However, we
646 // will have them as guarantees at the beginning / end of the bitmap
647 // clearing to get some checking in the product.
648 assert(_cm == NULL || _cm->cmThread()->during_cycle(), "invariant");
649 assert(_cm == NULL || !G1CollectedHeap::heap()->collector_state()->mark_in_progress(), "invariant");
650 }
651 assert(cur == end, "Must have completed iteration over the bitmap for region %u.", r->hrm_index());
652
653 return false;
654 }
655 };
656
657 G1ClearBitmapHRClosure _cl;
658 HeapRegionClaimer _hr_claimer;
659 bool _suspendible; // If the task is suspendible, workers must join the STS.
660
661 public:
662 G1ClearBitMapTask(G1CMBitMap* bitmap, G1ConcurrentMark* cm, uint n_workers, bool suspendible) :
663 AbstractGangTask("G1 Clear Bitmap"),
664 _cl(bitmap, suspendible ? cm : NULL),
665 _hr_claimer(n_workers),
666 _suspendible(suspendible)
667 { }
668
669 void work(uint worker_id) {
670 SuspendibleThreadSetJoiner sts_join(_suspendible);
671 G1CollectedHeap::heap()->heap_region_par_iterate(&_cl, worker_id, &_hr_claimer);
672 }
673
674 bool is_complete() {
675 return _cl.complete();
676 }
677 };
678
679 void G1ConcurrentMark::clear_bitmap(G1CMBitMap* bitmap, WorkGang* workers, bool may_yield) {
680 assert(may_yield || SafepointSynchronize::is_at_safepoint(), "Non-yielding bitmap clear only allowed at safepoint.");
681
682 size_t const num_bytes_to_clear = (HeapRegion::GrainBytes * _g1h->num_regions()) / G1CMBitMap::heap_map_factor();
683 size_t const num_chunks = align_up(num_bytes_to_clear, G1ClearBitMapTask::chunk_size()) / G1ClearBitMapTask::chunk_size();
684
685 uint const num_workers = (uint)MIN2(num_chunks, (size_t)workers->active_workers());
686
687 G1ClearBitMapTask cl(bitmap, this, num_workers, may_yield);
688
689 log_debug(gc, ergo)("Running %s with %u workers for " SIZE_FORMAT " work units.", cl.name(), num_workers, num_chunks);
690 workers->run_task(&cl, num_workers);
691 guarantee(!may_yield || cl.is_complete(), "Must have completed iteration when not yielding.");
692 }
693
694 void G1ConcurrentMark::cleanup_for_next_mark() {
695 // Make sure that the concurrent mark thread looks to still be in
696 // the current cycle.
697 guarantee(cmThread()->during_cycle(), "invariant");
698
699 // We are finishing up the current cycle by clearing the next
700 // marking bitmap and getting it ready for the next cycle. During
701 // this time no other cycle can start. So, let's make sure that this
702 // is the case.
703 guarantee(!_g1h->collector_state()->mark_in_progress(), "invariant");
704
705 clear_bitmap(_nextMarkBitMap, _parallel_workers, true);
706
707 // Clear the live count data. If the marking has been aborted, the abort()
708 // call already did that.
709 if (!has_aborted()) {
710 clear_live_data(_parallel_workers);
711 DEBUG_ONLY(verify_live_data_clear());
712 }
713
714 // Repeat the asserts from above.
715 guarantee(cmThread()->during_cycle(), "invariant");
716 guarantee(!_g1h->collector_state()->mark_in_progress(), "invariant");
717 }
718
719 void G1ConcurrentMark::clear_prev_bitmap(WorkGang* workers) {
720 assert(SafepointSynchronize::is_at_safepoint(), "Should only clear the entire prev bitmap at a safepoint.");
721 clear_bitmap(_prevMarkBitMap, workers, false);
722 }
723
724 class CheckBitmapClearHRClosure : public HeapRegionClosure {
725 G1CMBitMap* _bitmap;
726 bool _error;
727 public:
728 CheckBitmapClearHRClosure(G1CMBitMap* bitmap) : _bitmap(bitmap) {
729 }
730
731 virtual bool doHeapRegion(HeapRegion* r) {
732 // This closure can be called concurrently to the mutator, so we must make sure
733 // that the result of the getNextMarkedWordAddress() call is compared to the
734 // value passed to it as limit to detect any found bits.
735 // end never changes in G1.
736 HeapWord* end = r->end();
737 return _bitmap->get_next_marked_addr(r->bottom(), end) != end;
738 }
739 };
740
741 bool G1ConcurrentMark::nextMarkBitmapIsClear() {
742 CheckBitmapClearHRClosure cl(_nextMarkBitMap);
743 _g1h->heap_region_iterate(&cl);
744 return cl.complete();
745 }
746
747 class NoteStartOfMarkHRClosure: public HeapRegionClosure {
748 public:
749 bool doHeapRegion(HeapRegion* r) {
750 r->note_start_of_marking();
751 return false;
752 }
753 };
754
755 void G1ConcurrentMark::checkpointRootsInitialPre() {
756 G1CollectedHeap* g1h = G1CollectedHeap::heap();
757
758 _has_aborted = false;
759
760 // Initialize marking structures. This has to be done in a STW phase.
761 reset();
762
763 // For each region note start of marking.
764 NoteStartOfMarkHRClosure startcl;
765 g1h->heap_region_iterate(&startcl);
766 }
767
768
769 void G1ConcurrentMark::checkpointRootsInitialPost() {
770 G1CollectedHeap* g1h = G1CollectedHeap::heap();
771
772 // Start Concurrent Marking weak-reference discovery.
773 ReferenceProcessor* rp = g1h->ref_processor_cm();
774 // enable ("weak") refs discovery
775 rp->enable_discovery();
776 rp->setup_policy(false); // snapshot the soft ref policy to be used in this cycle
777
778 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
779 // This is the start of the marking cycle, we're expected all
780 // threads to have SATB queues with active set to false.
781 satb_mq_set.set_active_all_threads(true, /* new active value */
782 false /* expected_active */);
783
784 _root_regions.prepare_for_scan();
785
786 // update_g1_committed() will be called at the end of an evac pause
787 // when marking is on. So, it's also called at the end of the
788 // initial-mark pause to update the heap end, if the heap expands
789 // during it. No need to call it here.
790 }
791
792 /*
793 * Notice that in the next two methods, we actually leave the STS
794 * during the barrier sync and join it immediately afterwards. If we
795 * do not do this, the following deadlock can occur: one thread could
796 * be in the barrier sync code, waiting for the other thread to also
797 * sync up, whereas another one could be trying to yield, while also
798 * waiting for the other threads to sync up too.
799 *
800 * Note, however, that this code is also used during remark and in
801 * this case we should not attempt to leave / enter the STS, otherwise
802 * we'll either hit an assert (debug / fastdebug) or deadlock
803 * (product). So we should only leave / enter the STS if we are
804 * operating concurrently.
805 *
806 * Because the thread that does the sync barrier has left the STS, it
807 * is possible to be suspended for a Full GC or an evacuation pause
808 * could occur. This is actually safe, since the entering the sync
809 * barrier is one of the last things do_marking_step() does, and it
810 * doesn't manipulate any data structures afterwards.
811 */
812
813 void G1ConcurrentMark::enter_first_sync_barrier(uint worker_id) {
814 bool barrier_aborted;
815 {
816 SuspendibleThreadSetLeaver sts_leave(concurrent());
817 barrier_aborted = !_first_overflow_barrier_sync.enter();
818 }
819
820 // at this point everyone should have synced up and not be doing any
821 // more work
822
823 if (barrier_aborted) {
824 // If the barrier aborted we ignore the overflow condition and
825 // just abort the whole marking phase as quickly as possible.
826 return;
827 }
828
829 // If we're executing the concurrent phase of marking, reset the marking
830 // state; otherwise the marking state is reset after reference processing,
831 // during the remark pause.
832 // If we reset here as a result of an overflow during the remark we will
833 // see assertion failures from any subsequent set_concurrency_and_phase()
834 // calls.
835 if (concurrent()) {
836 // let the task associated with with worker 0 do this
837 if (worker_id == 0) {
838 // task 0 is responsible for clearing the global data structures
839 // We should be here because of an overflow. During STW we should
840 // not clear the overflow flag since we rely on it being true when
841 // we exit this method to abort the pause and restart concurrent
842 // marking.
843 reset_marking_state();
844
845 log_info(gc, marking)("Concurrent Mark reset for overflow");
846 }
847 }
848
849 // after this, each task should reset its own data structures then
850 // then go into the second barrier
851 }
852
853 void G1ConcurrentMark::enter_second_sync_barrier(uint worker_id) {
854 SuspendibleThreadSetLeaver sts_leave(concurrent());
855 _second_overflow_barrier_sync.enter();
856
857 // at this point everything should be re-initialized and ready to go
858 }
859
860 class G1CMConcurrentMarkingTask: public AbstractGangTask {
861 private:
862 G1ConcurrentMark* _cm;
863 ConcurrentMarkThread* _cmt;
864
865 public:
866 void work(uint worker_id) {
867 assert(Thread::current()->is_ConcurrentGC_thread(),
868 "this should only be done by a conc GC thread");
869 ResourceMark rm;
870
871 double start_vtime = os::elapsedVTime();
872
873 {
874 SuspendibleThreadSetJoiner sts_join;
875
876 assert(worker_id < _cm->active_tasks(), "invariant");
877 G1CMTask* the_task = _cm->task(worker_id);
878 the_task->record_start_time();
879 if (!_cm->has_aborted()) {
880 do {
881 double start_vtime_sec = os::elapsedVTime();
882 double mark_step_duration_ms = G1ConcMarkStepDurationMillis;
883
884 the_task->do_marking_step(mark_step_duration_ms,
885 true /* do_termination */,
886 false /* is_serial*/);
887
888 double end_vtime_sec = os::elapsedVTime();
889 double elapsed_vtime_sec = end_vtime_sec - start_vtime_sec;
890 _cm->do_yield_check();
891
892 jlong sleep_time_ms;
893 if (!_cm->has_aborted() && the_task->has_aborted()) {
894 sleep_time_ms =
895 (jlong) (elapsed_vtime_sec * _cm->sleep_factor() * 1000.0);
896 {
897 SuspendibleThreadSetLeaver sts_leave;
898 os::sleep(Thread::current(), sleep_time_ms, false);
899 }
900 }
901 } while (!_cm->has_aborted() && the_task->has_aborted());
902 }
903 the_task->record_end_time();
904 guarantee(!the_task->has_aborted() || _cm->has_aborted(), "invariant");
905 }
906
907 double end_vtime = os::elapsedVTime();
908 _cm->update_accum_task_vtime(worker_id, end_vtime - start_vtime);
909 }
910
911 G1CMConcurrentMarkingTask(G1ConcurrentMark* cm,
912 ConcurrentMarkThread* cmt) :
913 AbstractGangTask("Concurrent Mark"), _cm(cm), _cmt(cmt) { }
914
915 ~G1CMConcurrentMarkingTask() { }
916 };
917
918 // Calculates the number of active workers for a concurrent
919 // phase.
920 uint G1ConcurrentMark::calc_parallel_marking_threads() {
921 uint n_conc_workers = 0;
922 if (!UseDynamicNumberOfGCThreads ||
923 (!FLAG_IS_DEFAULT(ConcGCThreads) &&
924 !ForceDynamicNumberOfGCThreads)) {
925 n_conc_workers = max_parallel_marking_threads();
926 } else {
927 n_conc_workers =
928 AdaptiveSizePolicy::calc_default_active_workers(max_parallel_marking_threads(),
929 1, /* Minimum workers */
930 parallel_marking_threads(),
931 Threads::number_of_non_daemon_threads());
932 // Don't scale down "n_conc_workers" by scale_parallel_threads() because
933 // that scaling has already gone into "_max_parallel_marking_threads".
934 }
935 assert(n_conc_workers > 0 && n_conc_workers <= max_parallel_marking_threads(),
936 "Calculated number of workers must be larger than zero and at most the maximum %u, but is %u",
937 max_parallel_marking_threads(), n_conc_workers);
938 return n_conc_workers;
939 }
940
941 void G1ConcurrentMark::scanRootRegion(HeapRegion* hr) {
942 // Currently, only survivors can be root regions.
943 assert(hr->next_top_at_mark_start() == hr->bottom(), "invariant");
944 G1RootRegionScanClosure cl(_g1h, this);
945
946 const uintx interval = PrefetchScanIntervalInBytes;
947 HeapWord* curr = hr->bottom();
948 const HeapWord* end = hr->top();
949 while (curr < end) {
950 Prefetch::read(curr, interval);
951 oop obj = oop(curr);
952 int size = obj->oop_iterate_size(&cl);
953 assert(size == obj->size(), "sanity");
954 curr += size;
955 }
956 }
957
958 class G1CMRootRegionScanTask : public AbstractGangTask {
959 private:
960 G1ConcurrentMark* _cm;
961
962 public:
963 G1CMRootRegionScanTask(G1ConcurrentMark* cm) :
964 AbstractGangTask("G1 Root Region Scan"), _cm(cm) { }
965
966 void work(uint worker_id) {
967 assert(Thread::current()->is_ConcurrentGC_thread(),
968 "this should only be done by a conc GC thread");
969
970 G1CMRootRegions* root_regions = _cm->root_regions();
971 HeapRegion* hr = root_regions->claim_next();
972 while (hr != NULL) {
973 _cm->scanRootRegion(hr);
974 hr = root_regions->claim_next();
975 }
976 }
977 };
978
979 void G1ConcurrentMark::scan_root_regions() {
980 // scan_in_progress() will have been set to true only if there was
981 // at least one root region to scan. So, if it's false, we
982 // should not attempt to do any further work.
983 if (root_regions()->scan_in_progress()) {
984 assert(!has_aborted(), "Aborting before root region scanning is finished not supported.");
985
986 _parallel_marking_threads = MIN2(calc_parallel_marking_threads(),
987 // We distribute work on a per-region basis, so starting
988 // more threads than that is useless.
989 root_regions()->num_root_regions());
990 assert(parallel_marking_threads() <= max_parallel_marking_threads(),
991 "Maximum number of marking threads exceeded");
992
993 G1CMRootRegionScanTask task(this);
994 log_debug(gc, ergo)("Running %s using %u workers for %u work units.",
995 task.name(), _parallel_marking_threads, root_regions()->num_root_regions());
996 _parallel_workers->run_task(&task, _parallel_marking_threads);
997
998 // It's possible that has_aborted() is true here without actually
999 // aborting the survivor scan earlier. This is OK as it's
1000 // mainly used for sanity checking.
1001 root_regions()->scan_finished();
1002 }
1003 }
1004
1005 void G1ConcurrentMark::concurrent_cycle_start() {
1006 _gc_timer_cm->register_gc_start();
1007
1008 _gc_tracer_cm->report_gc_start(GCCause::_no_gc /* first parameter is not used */, _gc_timer_cm->gc_start());
1009
1010 _g1h->trace_heap_before_gc(_gc_tracer_cm);
1011 }
1012
1013 void G1ConcurrentMark::concurrent_cycle_end() {
1014 _g1h->trace_heap_after_gc(_gc_tracer_cm);
1015
1016 if (has_aborted()) {
1017 _gc_tracer_cm->report_concurrent_mode_failure();
1018 }
1019
1020 _gc_timer_cm->register_gc_end();
1021
1022 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
1023 }
1024
1025 void G1ConcurrentMark::mark_from_roots() {
1026 // we might be tempted to assert that:
1027 // assert(asynch == !SafepointSynchronize::is_at_safepoint(),
1028 // "inconsistent argument?");
1029 // However that wouldn't be right, because it's possible that
1030 // a safepoint is indeed in progress as a younger generation
1031 // stop-the-world GC happens even as we mark in this generation.
1032
1033 _restart_for_overflow = false;
1034
1035 // _g1h has _n_par_threads
1036 _parallel_marking_threads = calc_parallel_marking_threads();
1037 assert(parallel_marking_threads() <= max_parallel_marking_threads(),
1038 "Maximum number of marking threads exceeded");
1039
1040 uint active_workers = MAX2(1U, parallel_marking_threads());
1041 assert(active_workers > 0, "Should have been set");
1042
1043 // Setting active workers is not guaranteed since fewer
1044 // worker threads may currently exist and more may not be
1045 // available.
1046 active_workers = _parallel_workers->update_active_workers(active_workers);
1047 log_info(gc, task)("Using %u workers of %u for marking", active_workers, _parallel_workers->total_workers());
1048
1049 // Parallel task terminator is set in "set_concurrency_and_phase()"
1050 set_concurrency_and_phase(active_workers, true /* concurrent */);
1051
1052 G1CMConcurrentMarkingTask markingTask(this, cmThread());
1053 _parallel_workers->run_task(&markingTask);
1054 print_stats();
1055 }
1056
1057 void G1ConcurrentMark::checkpointRootsFinal(bool clear_all_soft_refs) {
1058 // world is stopped at this checkpoint
1059 assert(SafepointSynchronize::is_at_safepoint(),
1060 "world should be stopped");
1061
1062 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1063
1064 // If a full collection has happened, we shouldn't do this.
1065 if (has_aborted()) {
1066 g1h->collector_state()->set_mark_in_progress(false); // So bitmap clearing isn't confused
1067 return;
1068 }
1069
1070 SvcGCMarker sgcm(SvcGCMarker::OTHER);
1071
1072 if (VerifyDuringGC) {
1073 HandleMark hm; // handle scope
1074 g1h->prepare_for_verify();
1075 Universe::verify(VerifyOption_G1UsePrevMarking, "During GC (before)");
1076 }
1077 g1h->verifier()->check_bitmaps("Remark Start");
1078
1079 G1Policy* g1p = g1h->g1_policy();
1080 g1p->record_concurrent_mark_remark_start();
1081
1082 double start = os::elapsedTime();
1083
1084 checkpointRootsFinalWork();
1085
1086 double mark_work_end = os::elapsedTime();
1087
1088 weakRefsWork(clear_all_soft_refs);
1089
1090 if (has_overflown()) {
1091 // We overflowed. Restart concurrent marking.
1092 _restart_for_overflow = true;
1093
1094 // Verify the heap w.r.t. the previous marking bitmap.
1095 if (VerifyDuringGC) {
1096 HandleMark hm; // handle scope
1097 g1h->prepare_for_verify();
1098 Universe::verify(VerifyOption_G1UsePrevMarking, "During GC (overflow)");
1099 }
1100
1101 // Clear the marking state because we will be restarting
1102 // marking due to overflowing the global mark stack.
1103 reset_marking_state();
1104 } else {
1105 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
1106 // We're done with marking.
1107 // This is the end of the marking cycle, we're expected all
1108 // threads to have SATB queues with active set to true.
1109 satb_mq_set.set_active_all_threads(false, /* new active value */
1110 true /* expected_active */);
1111
1112 if (VerifyDuringGC) {
1113 HandleMark hm; // handle scope
1114 g1h->prepare_for_verify();
1115 Universe::verify(VerifyOption_G1UseNextMarking, "During GC (after)");
1116 }
1117 g1h->verifier()->check_bitmaps("Remark End");
1118 assert(!restart_for_overflow(), "sanity");
1119 // Completely reset the marking state since marking completed
1120 set_non_marking_state();
1121 }
1122
1123 // Statistics
1124 double now = os::elapsedTime();
1125 _remark_mark_times.add((mark_work_end - start) * 1000.0);
1126 _remark_weak_ref_times.add((now - mark_work_end) * 1000.0);
1127 _remark_times.add((now - start) * 1000.0);
1128
1129 g1p->record_concurrent_mark_remark_end();
1130
1131 G1CMIsAliveClosure is_alive(g1h);
1132 _gc_tracer_cm->report_object_count_after_gc(&is_alive);
1133 }
1134
1135 class G1NoteEndOfConcMarkClosure : public HeapRegionClosure {
1136 G1CollectedHeap* _g1;
1137 size_t _freed_bytes;
1138 FreeRegionList* _local_cleanup_list;
1139 uint _old_regions_removed;
1140 uint _humongous_regions_removed;
1141 HRRSCleanupTask* _hrrs_cleanup_task;
1142
1143 public:
1144 G1NoteEndOfConcMarkClosure(G1CollectedHeap* g1,
1145 FreeRegionList* local_cleanup_list,
1146 HRRSCleanupTask* hrrs_cleanup_task) :
1147 _g1(g1),
1148 _freed_bytes(0),
1149 _local_cleanup_list(local_cleanup_list),
1150 _old_regions_removed(0),
1151 _humongous_regions_removed(0),
1152 _hrrs_cleanup_task(hrrs_cleanup_task) { }
1153
1154 size_t freed_bytes() { return _freed_bytes; }
1155 const uint old_regions_removed() { return _old_regions_removed; }
1156 const uint humongous_regions_removed() { return _humongous_regions_removed; }
1157
1158 bool doHeapRegion(HeapRegion *hr) {
1159 if (hr->is_archive()) {
1160 return false;
1161 }
1162 _g1->reset_gc_time_stamps(hr);
1163 hr->note_end_of_marking();
1164
1165 if (hr->used() > 0 && hr->max_live_bytes() == 0 && !hr->is_young()) {
1166 _freed_bytes += hr->used();
1167 hr->set_containing_set(NULL);
1168 if (hr->is_humongous()) {
1169 _humongous_regions_removed++;
1170 _g1->free_humongous_region(hr, _local_cleanup_list, true /* skip_remset */);
1171 } else {
1172 _old_regions_removed++;
1173 _g1->free_region(hr, _local_cleanup_list, true /* skip_remset */);
1174 }
1175 } else {
1176 hr->rem_set()->do_cleanup_work(_hrrs_cleanup_task);
1177 }
1178
1179 return false;
1180 }
1181 };
1182
1183 class G1ParNoteEndTask: public AbstractGangTask {
1184 friend class G1NoteEndOfConcMarkClosure;
1185
1186 protected:
1187 G1CollectedHeap* _g1h;
1188 FreeRegionList* _cleanup_list;
1189 HeapRegionClaimer _hrclaimer;
1190
1191 public:
1192 G1ParNoteEndTask(G1CollectedHeap* g1h, FreeRegionList* cleanup_list, uint n_workers) :
1193 AbstractGangTask("G1 note end"), _g1h(g1h), _cleanup_list(cleanup_list), _hrclaimer(n_workers) {
1194 }
1195
1196 void work(uint worker_id) {
1197 FreeRegionList local_cleanup_list("Local Cleanup List");
1198 HRRSCleanupTask hrrs_cleanup_task;
1199 G1NoteEndOfConcMarkClosure g1_note_end(_g1h, &local_cleanup_list,
1200 &hrrs_cleanup_task);
1201 _g1h->heap_region_par_iterate(&g1_note_end, worker_id, &_hrclaimer);
1202 assert(g1_note_end.complete(), "Shouldn't have yielded!");
1203
1204 // Now update the lists
1205 _g1h->remove_from_old_sets(g1_note_end.old_regions_removed(), g1_note_end.humongous_regions_removed());
1206 {
1207 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
1208 _g1h->decrement_summary_bytes(g1_note_end.freed_bytes());
1209
1210 // If we iterate over the global cleanup list at the end of
1211 // cleanup to do this printing we will not guarantee to only
1212 // generate output for the newly-reclaimed regions (the list
1213 // might not be empty at the beginning of cleanup; we might
1214 // still be working on its previous contents). So we do the
1215 // printing here, before we append the new regions to the global
1216 // cleanup list.
1217
1218 G1HRPrinter* hr_printer = _g1h->hr_printer();
1219 if (hr_printer->is_active()) {
1220 FreeRegionListIterator iter(&local_cleanup_list);
1221 while (iter.more_available()) {
1222 HeapRegion* hr = iter.get_next();
1223 hr_printer->cleanup(hr);
1224 }
1225 }
1226
1227 _cleanup_list->add_ordered(&local_cleanup_list);
1228 assert(local_cleanup_list.is_empty(), "post-condition");
1229
1230 HeapRegionRemSet::finish_cleanup_task(&hrrs_cleanup_task);
1231 }
1232 }
1233 };
1234
1235 void G1ConcurrentMark::cleanup() {
1236 // world is stopped at this checkpoint
1237 assert(SafepointSynchronize::is_at_safepoint(),
1238 "world should be stopped");
1239 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1240
1241 // If a full collection has happened, we shouldn't do this.
1242 if (has_aborted()) {
1243 g1h->collector_state()->set_mark_in_progress(false); // So bitmap clearing isn't confused
1244 return;
1245 }
1246
1247 g1h->verifier()->verify_region_sets_optional();
1248
1249 if (VerifyDuringGC) {
1250 HandleMark hm; // handle scope
1251 g1h->prepare_for_verify();
1252 Universe::verify(VerifyOption_G1UsePrevMarking, "During GC (before)");
1253 }
1254 g1h->verifier()->check_bitmaps("Cleanup Start");
1255
1256 G1Policy* g1p = g1h->g1_policy();
1257 g1p->record_concurrent_mark_cleanup_start();
1258
1259 double start = os::elapsedTime();
1260
1261 HeapRegionRemSet::reset_for_cleanup_tasks();
1262
1263 {
1264 GCTraceTime(Debug, gc)("Finalize Live Data");
1265 finalize_live_data();
1266 }
1267
1268 if (VerifyDuringGC) {
1269 GCTraceTime(Debug, gc)("Verify Live Data");
1270 verify_live_data();
1271 }
1272
1273 g1h->collector_state()->set_mark_in_progress(false);
1274
1275 double count_end = os::elapsedTime();
1276 double this_final_counting_time = (count_end - start);
1277 _total_counting_time += this_final_counting_time;
1278
1279 if (log_is_enabled(Trace, gc, liveness)) {
1280 G1PrintRegionLivenessInfoClosure cl("Post-Marking");
1281 _g1h->heap_region_iterate(&cl);
1282 }
1283
1284 // Install newly created mark bitMap as "prev".
1285 swapMarkBitMaps();
1286
1287 g1h->reset_gc_time_stamp();
1288
1289 uint n_workers = _g1h->workers()->active_workers();
1290
1291 // Note end of marking in all heap regions.
1292 G1ParNoteEndTask g1_par_note_end_task(g1h, &_cleanup_list, n_workers);
1293 g1h->workers()->run_task(&g1_par_note_end_task);
1294 g1h->check_gc_time_stamps();
1295
1296 if (!cleanup_list_is_empty()) {
1297 // The cleanup list is not empty, so we'll have to process it
1298 // concurrently. Notify anyone else that might be wanting free
1299 // regions that there will be more free regions coming soon.
1300 g1h->set_free_regions_coming();
1301 }
1302
1303 // call below, since it affects the metric by which we sort the heap
1304 // regions.
1305 if (G1ScrubRemSets) {
1306 double rs_scrub_start = os::elapsedTime();
1307 g1h->scrub_rem_set();
1308 _total_rs_scrub_time += (os::elapsedTime() - rs_scrub_start);
1309 }
1310
1311 // this will also free any regions totally full of garbage objects,
1312 // and sort the regions.
1313 g1h->g1_policy()->record_concurrent_mark_cleanup_end();
1314
1315 // Statistics.
1316 double end = os::elapsedTime();
1317 _cleanup_times.add((end - start) * 1000.0);
1318
1319 // Clean up will have freed any regions completely full of garbage.
1320 // Update the soft reference policy with the new heap occupancy.
1321 Universe::update_heap_info_at_gc();
1322
1323 if (VerifyDuringGC) {
1324 HandleMark hm; // handle scope
1325 g1h->prepare_for_verify();
1326 Universe::verify(VerifyOption_G1UsePrevMarking, "During GC (after)");
1327 }
1328
1329 g1h->verifier()->check_bitmaps("Cleanup End");
1330
1331 g1h->verifier()->verify_region_sets_optional();
1332
1333 // We need to make this be a "collection" so any collection pause that
1334 // races with it goes around and waits for completeCleanup to finish.
1335 g1h->increment_total_collections();
1336
1337 // Clean out dead classes and update Metaspace sizes.
1338 if (ClassUnloadingWithConcurrentMark) {
1339 ClassLoaderDataGraph::purge();
1340 }
1341 MetaspaceGC::compute_new_size();
1342
1343 // We reclaimed old regions so we should calculate the sizes to make
1344 // sure we update the old gen/space data.
1345 g1h->g1mm()->update_sizes();
1346 g1h->allocation_context_stats().update_after_mark();
1347 }
1348
1349 void G1ConcurrentMark::complete_cleanup() {
1350 if (has_aborted()) return;
1351
1352 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1353
1354 _cleanup_list.verify_optional();
1355 FreeRegionList tmp_free_list("Tmp Free List");
1356
1357 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [complete cleanup] : "
1358 "cleanup list has %u entries",
1359 _cleanup_list.length());
1360
1361 // No one else should be accessing the _cleanup_list at this point,
1362 // so it is not necessary to take any locks
1363 while (!_cleanup_list.is_empty()) {
1364 HeapRegion* hr = _cleanup_list.remove_region(true /* from_head */);
1365 assert(hr != NULL, "Got NULL from a non-empty list");
1366 hr->par_clear();
1367 tmp_free_list.add_ordered(hr);
1368
1369 // Instead of adding one region at a time to the secondary_free_list,
1370 // we accumulate them in the local list and move them a few at a
1371 // time. This also cuts down on the number of notify_all() calls
1372 // we do during this process. We'll also append the local list when
1373 // _cleanup_list is empty (which means we just removed the last
1374 // region from the _cleanup_list).
1375 if ((tmp_free_list.length() % G1SecondaryFreeListAppendLength == 0) ||
1376 _cleanup_list.is_empty()) {
1377 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [complete cleanup] : "
1378 "appending %u entries to the secondary_free_list, "
1379 "cleanup list still has %u entries",
1380 tmp_free_list.length(),
1381 _cleanup_list.length());
1382
1383 {
1384 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
1385 g1h->secondary_free_list_add(&tmp_free_list);
1386 SecondaryFreeList_lock->notify_all();
1387 }
1388 #ifndef PRODUCT
1389 if (G1StressConcRegionFreeing) {
1390 for (uintx i = 0; i < G1StressConcRegionFreeingDelayMillis; ++i) {
1391 os::sleep(Thread::current(), (jlong) 1, false);
1392 }
1393 }
1394 #endif
1395 }
1396 }
1397 assert(tmp_free_list.is_empty(), "post-condition");
1398 }
1399
1400 // Supporting Object and Oop closures for reference discovery
1401 // and processing in during marking
1402
1403 bool G1CMIsAliveClosure::do_object_b(oop obj) {
1404 HeapWord* addr = (HeapWord*)obj;
1405 return addr != NULL &&
1406 (!_g1->is_in_g1_reserved(addr) || !_g1->is_obj_ill(obj));
1407 }
1408
1409 // 'Keep Alive' oop closure used by both serial parallel reference processing.
1410 // Uses the G1CMTask associated with a worker thread (for serial reference
1411 // processing the G1CMTask for worker 0 is used) to preserve (mark) and
1412 // trace referent objects.
1413 //
1414 // Using the G1CMTask and embedded local queues avoids having the worker
1415 // threads operating on the global mark stack. This reduces the risk
1416 // of overflowing the stack - which we would rather avoid at this late
1417 // state. Also using the tasks' local queues removes the potential
1418 // of the workers interfering with each other that could occur if
1419 // operating on the global stack.
1420
1421 class G1CMKeepAliveAndDrainClosure: public OopClosure {
1422 G1ConcurrentMark* _cm;
1423 G1CMTask* _task;
1424 int _ref_counter_limit;
1425 int _ref_counter;
1426 bool _is_serial;
1427 public:
1428 G1CMKeepAliveAndDrainClosure(G1ConcurrentMark* cm, G1CMTask* task, bool is_serial) :
1429 _cm(cm), _task(task), _is_serial(is_serial),
1430 _ref_counter_limit(G1RefProcDrainInterval) {
1431 assert(_ref_counter_limit > 0, "sanity");
1432 assert(!_is_serial || _task->worker_id() == 0, "only task 0 for serial code");
1433 _ref_counter = _ref_counter_limit;
1434 }
1435
1436 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
1437 virtual void do_oop( oop* p) { do_oop_work(p); }
1438
1439 template <class T> void do_oop_work(T* p) {
1440 if (!_cm->has_overflown()) {
1441 oop obj = oopDesc::load_decode_heap_oop(p);
1442 _task->deal_with_reference(obj);
1443 _ref_counter--;
1444
1445 if (_ref_counter == 0) {
1446 // We have dealt with _ref_counter_limit references, pushing them
1447 // and objects reachable from them on to the local stack (and
1448 // possibly the global stack). Call G1CMTask::do_marking_step() to
1449 // process these entries.
1450 //
1451 // We call G1CMTask::do_marking_step() in a loop, which we'll exit if
1452 // there's nothing more to do (i.e. we're done with the entries that
1453 // were pushed as a result of the G1CMTask::deal_with_reference() calls
1454 // above) or we overflow.
1455 //
1456 // Note: G1CMTask::do_marking_step() can set the G1CMTask::has_aborted()
1457 // flag while there may still be some work to do. (See the comment at
1458 // the beginning of G1CMTask::do_marking_step() for those conditions -
1459 // one of which is reaching the specified time target.) It is only
1460 // when G1CMTask::do_marking_step() returns without setting the
1461 // has_aborted() flag that the marking step has completed.
1462 do {
1463 double mark_step_duration_ms = G1ConcMarkStepDurationMillis;
1464 _task->do_marking_step(mark_step_duration_ms,
1465 false /* do_termination */,
1466 _is_serial);
1467 } while (_task->has_aborted() && !_cm->has_overflown());
1468 _ref_counter = _ref_counter_limit;
1469 }
1470 }
1471 }
1472 };
1473
1474 // 'Drain' oop closure used by both serial and parallel reference processing.
1475 // Uses the G1CMTask associated with a given worker thread (for serial
1476 // reference processing the G1CMtask for worker 0 is used). Calls the
1477 // do_marking_step routine, with an unbelievably large timeout value,
1478 // to drain the marking data structures of the remaining entries
1479 // added by the 'keep alive' oop closure above.
1480
1481 class G1CMDrainMarkingStackClosure: public VoidClosure {
1482 G1ConcurrentMark* _cm;
1483 G1CMTask* _task;
1484 bool _is_serial;
1485 public:
1486 G1CMDrainMarkingStackClosure(G1ConcurrentMark* cm, G1CMTask* task, bool is_serial) :
1487 _cm(cm), _task(task), _is_serial(is_serial) {
1488 assert(!_is_serial || _task->worker_id() == 0, "only task 0 for serial code");
1489 }
1490
1491 void do_void() {
1492 do {
1493 // We call G1CMTask::do_marking_step() to completely drain the local
1494 // and global marking stacks of entries pushed by the 'keep alive'
1495 // oop closure (an instance of G1CMKeepAliveAndDrainClosure above).
1496 //
1497 // G1CMTask::do_marking_step() is called in a loop, which we'll exit
1498 // if there's nothing more to do (i.e. we've completely drained the
1499 // entries that were pushed as a a result of applying the 'keep alive'
1500 // closure to the entries on the discovered ref lists) or we overflow
1501 // the global marking stack.
1502 //
1503 // Note: G1CMTask::do_marking_step() can set the G1CMTask::has_aborted()
1504 // flag while there may still be some work to do. (See the comment at
1505 // the beginning of G1CMTask::do_marking_step() for those conditions -
1506 // one of which is reaching the specified time target.) It is only
1507 // when G1CMTask::do_marking_step() returns without setting the
1508 // has_aborted() flag that the marking step has completed.
1509
1510 _task->do_marking_step(1000000000.0 /* something very large */,
1511 true /* do_termination */,
1512 _is_serial);
1513 } while (_task->has_aborted() && !_cm->has_overflown());
1514 }
1515 };
1516
1517 // Implementation of AbstractRefProcTaskExecutor for parallel
1518 // reference processing at the end of G1 concurrent marking
1519
1520 class G1CMRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
1521 private:
1522 G1CollectedHeap* _g1h;
1523 G1ConcurrentMark* _cm;
1524 WorkGang* _workers;
1525 uint _active_workers;
1526
1527 public:
1528 G1CMRefProcTaskExecutor(G1CollectedHeap* g1h,
1529 G1ConcurrentMark* cm,
1530 WorkGang* workers,
1531 uint n_workers) :
1532 _g1h(g1h), _cm(cm),
1533 _workers(workers), _active_workers(n_workers) { }
1534
1535 // Executes the given task using concurrent marking worker threads.
1536 virtual void execute(ProcessTask& task);
1537 virtual void execute(EnqueueTask& task);
1538 };
1539
1540 class G1CMRefProcTaskProxy: public AbstractGangTask {
1541 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
1542 ProcessTask& _proc_task;
1543 G1CollectedHeap* _g1h;
1544 G1ConcurrentMark* _cm;
1545
1546 public:
1547 G1CMRefProcTaskProxy(ProcessTask& proc_task,
1548 G1CollectedHeap* g1h,
1549 G1ConcurrentMark* cm) :
1550 AbstractGangTask("Process reference objects in parallel"),
1551 _proc_task(proc_task), _g1h(g1h), _cm(cm) {
1552 ReferenceProcessor* rp = _g1h->ref_processor_cm();
1553 assert(rp->processing_is_mt(), "shouldn't be here otherwise");
1554 }
1555
1556 virtual void work(uint worker_id) {
1557 ResourceMark rm;
1558 HandleMark hm;
1559 G1CMTask* task = _cm->task(worker_id);
1560 G1CMIsAliveClosure g1_is_alive(_g1h);
1561 G1CMKeepAliveAndDrainClosure g1_par_keep_alive(_cm, task, false /* is_serial */);
1562 G1CMDrainMarkingStackClosure g1_par_drain(_cm, task, false /* is_serial */);
1563
1564 _proc_task.work(worker_id, g1_is_alive, g1_par_keep_alive, g1_par_drain);
1565 }
1566 };
1567
1568 void G1CMRefProcTaskExecutor::execute(ProcessTask& proc_task) {
1569 assert(_workers != NULL, "Need parallel worker threads.");
1570 assert(_g1h->ref_processor_cm()->processing_is_mt(), "processing is not MT");
1571
1572 G1CMRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _cm);
1573
1574 // We need to reset the concurrency level before each
1575 // proxy task execution, so that the termination protocol
1576 // and overflow handling in G1CMTask::do_marking_step() knows
1577 // how many workers to wait for.
1578 _cm->set_concurrency(_active_workers);
1579 _workers->run_task(&proc_task_proxy);
1580 }
1581
1582 class G1CMRefEnqueueTaskProxy: public AbstractGangTask {
1583 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
1584 EnqueueTask& _enq_task;
1585
1586 public:
1587 G1CMRefEnqueueTaskProxy(EnqueueTask& enq_task) :
1588 AbstractGangTask("Enqueue reference objects in parallel"),
1589 _enq_task(enq_task) { }
1590
1591 virtual void work(uint worker_id) {
1592 _enq_task.work(worker_id);
1593 }
1594 };
1595
1596 void G1CMRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
1597 assert(_workers != NULL, "Need parallel worker threads.");
1598 assert(_g1h->ref_processor_cm()->processing_is_mt(), "processing is not MT");
1599
1600 G1CMRefEnqueueTaskProxy enq_task_proxy(enq_task);
1601
1602 // Not strictly necessary but...
1603 //
1604 // We need to reset the concurrency level before each
1605 // proxy task execution, so that the termination protocol
1606 // and overflow handling in G1CMTask::do_marking_step() knows
1607 // how many workers to wait for.
1608 _cm->set_concurrency(_active_workers);
1609 _workers->run_task(&enq_task_proxy);
1610 }
1611
1612 void G1ConcurrentMark::weakRefsWork(bool clear_all_soft_refs) {
1613 if (has_overflown()) {
1614 // Skip processing the discovered references if we have
1615 // overflown the global marking stack. Reference objects
1616 // only get discovered once so it is OK to not
1617 // de-populate the discovered reference lists. We could have,
1618 // but the only benefit would be that, when marking restarts,
1619 // less reference objects are discovered.
1620 return;
1621 }
1622
1623 ResourceMark rm;
1624 HandleMark hm;
1625
1626 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1627
1628 // Is alive closure.
1629 G1CMIsAliveClosure g1_is_alive(g1h);
1630
1631 // Inner scope to exclude the cleaning of the string and symbol
1632 // tables from the displayed time.
1633 {
1634 GCTraceTime(Debug, gc, phases) trace("Reference Processing", _gc_timer_cm);
1635
1636 ReferenceProcessor* rp = g1h->ref_processor_cm();
1637
1638 // See the comment in G1CollectedHeap::ref_processing_init()
1639 // about how reference processing currently works in G1.
1640
1641 // Set the soft reference policy
1642 rp->setup_policy(clear_all_soft_refs);
1643 assert(_global_mark_stack.is_empty(), "mark stack should be empty");
1644
1645 // Instances of the 'Keep Alive' and 'Complete GC' closures used
1646 // in serial reference processing. Note these closures are also
1647 // used for serially processing (by the the current thread) the
1648 // JNI references during parallel reference processing.
1649 //
1650 // These closures do not need to synchronize with the worker
1651 // threads involved in parallel reference processing as these
1652 // instances are executed serially by the current thread (e.g.
1653 // reference processing is not multi-threaded and is thus
1654 // performed by the current thread instead of a gang worker).
1655 //
1656 // The gang tasks involved in parallel reference processing create
1657 // their own instances of these closures, which do their own
1658 // synchronization among themselves.
1659 G1CMKeepAliveAndDrainClosure g1_keep_alive(this, task(0), true /* is_serial */);
1660 G1CMDrainMarkingStackClosure g1_drain_mark_stack(this, task(0), true /* is_serial */);
1661
1662 // We need at least one active thread. If reference processing
1663 // is not multi-threaded we use the current (VMThread) thread,
1664 // otherwise we use the work gang from the G1CollectedHeap and
1665 // we utilize all the worker threads we can.
1666 bool processing_is_mt = rp->processing_is_mt();
1667 uint active_workers = (processing_is_mt ? g1h->workers()->active_workers() : 1U);
1668 active_workers = MAX2(MIN2(active_workers, _max_worker_id), 1U);
1669
1670 // Parallel processing task executor.
1671 G1CMRefProcTaskExecutor par_task_executor(g1h, this,
1672 g1h->workers(), active_workers);
1673 AbstractRefProcTaskExecutor* executor = (processing_is_mt ? &par_task_executor : NULL);
1674
1675 // Set the concurrency level. The phase was already set prior to
1676 // executing the remark task.
1677 set_concurrency(active_workers);
1678
1679 // Set the degree of MT processing here. If the discovery was done MT,
1680 // the number of threads involved during discovery could differ from
1681 // the number of active workers. This is OK as long as the discovered
1682 // Reference lists are balanced (see balance_all_queues() and balance_queues()).
1683 rp->set_active_mt_degree(active_workers);
1684
1685 // Process the weak references.
1686 const ReferenceProcessorStats& stats =
1687 rp->process_discovered_references(&g1_is_alive,
1688 &g1_keep_alive,
1689 &g1_drain_mark_stack,
1690 executor,
1691 _gc_timer_cm);
1692 _gc_tracer_cm->report_gc_reference_stats(stats);
1693
1694 // The do_oop work routines of the keep_alive and drain_marking_stack
1695 // oop closures will set the has_overflown flag if we overflow the
1696 // global marking stack.
1697
1698 assert(has_overflown() || _global_mark_stack.is_empty(),
1699 "Mark stack should be empty (unless it has overflown)");
1700
1701 assert(rp->num_q() == active_workers, "why not");
1702
1703 rp->enqueue_discovered_references(executor);
1704
1705 rp->verify_no_references_recorded();
1706 assert(!rp->discovery_enabled(), "Post condition");
1707 }
1708
1709 if (has_overflown()) {
1710 // We can not trust g1_is_alive if the marking stack overflowed
1711 return;
1712 }
1713
1714 assert(_global_mark_stack.is_empty(), "Marking should have completed");
1715
1716 // Unload Klasses, String, Symbols, Code Cache, etc.
1717 if (ClassUnloadingWithConcurrentMark) {
1718 GCTraceTime(Debug, gc, phases) debug("Class Unloading", _gc_timer_cm);
1719 bool purged_classes = SystemDictionary::do_unloading(&g1_is_alive, _gc_timer_cm, false /* Defer cleaning */);
1720 g1h->complete_cleaning(&g1_is_alive, purged_classes);
1721 } else {
1722 GCTraceTime(Debug, gc, phases) debug("Cleanup", _gc_timer_cm);
1723 // No need to clean string table and symbol table as they are treated as strong roots when
1724 // class unloading is disabled.
1725 g1h->partial_cleaning(&g1_is_alive, false, false, G1StringDedup::is_enabled());
1726
1727 }
1728 }
1729
1730 void G1ConcurrentMark::swapMarkBitMaps() {
1731 G1CMBitMap* temp = _prevMarkBitMap;
1732 _prevMarkBitMap = _nextMarkBitMap;
1733 _nextMarkBitMap = temp;
1734 }
1735
1736 // Closure for marking entries in SATB buffers.
1737 class G1CMSATBBufferClosure : public SATBBufferClosure {
1738 private:
1739 G1CMTask* _task;
1740 G1CollectedHeap* _g1h;
1741
1742 // This is very similar to G1CMTask::deal_with_reference, but with
1743 // more relaxed requirements for the argument, so this must be more
1744 // circumspect about treating the argument as an object.
1745 void do_entry(void* entry) const {
1746 _task->increment_refs_reached();
1747 HeapRegion* hr = _g1h->heap_region_containing(entry);
1748 if (entry < hr->next_top_at_mark_start()) {
1749 // Until we get here, we don't know whether entry refers to a valid
1750 // object; it could instead have been a stale reference.
1751 oop obj = static_cast<oop>(entry);
1752 assert(obj->is_oop(true /* ignore mark word */),
1753 "Invalid oop in SATB buffer: " PTR_FORMAT, p2i(obj));
1754 _task->make_reference_grey(obj);
1755 }
1756 }
1757
1758 public:
1759 G1CMSATBBufferClosure(G1CMTask* task, G1CollectedHeap* g1h)
1760 : _task(task), _g1h(g1h) { }
1761
1762 virtual void do_buffer(void** buffer, size_t size) {
1763 for (size_t i = 0; i < size; ++i) {
1764 do_entry(buffer[i]);
1765 }
1766 }
1767 };
1768
1769 class G1RemarkThreadsClosure : public ThreadClosure {
1770 G1CMSATBBufferClosure _cm_satb_cl;
1771 G1CMOopClosure _cm_cl;
1772 MarkingCodeBlobClosure _code_cl;
1773 int _thread_parity;
1774
1775 public:
1776 G1RemarkThreadsClosure(G1CollectedHeap* g1h, G1CMTask* task) :
1777 _cm_satb_cl(task, g1h),
1778 _cm_cl(g1h, g1h->concurrent_mark(), task),
1779 _code_cl(&_cm_cl, !CodeBlobToOopClosure::FixRelocations),
1780 _thread_parity(Threads::thread_claim_parity()) {}
1781
1782 void do_thread(Thread* thread) {
1783 if (thread->is_Java_thread()) {
1784 if (thread->claim_oops_do(true, _thread_parity)) {
1785 JavaThread* jt = (JavaThread*)thread;
1786
1787 // In theory it should not be neccessary to explicitly walk the nmethods to find roots for concurrent marking
1788 // however the liveness of oops reachable from nmethods have very complex lifecycles:
1789 // * Alive if on the stack of an executing method
1790 // * Weakly reachable otherwise
1791 // Some objects reachable from nmethods, such as the class loader (or klass_holder) of the receiver should be
1792 // live by the SATB invariant but other oops recorded in nmethods may behave differently.
1793 jt->nmethods_do(&_code_cl);
1794
1795 jt->satb_mark_queue().apply_closure_and_empty(&_cm_satb_cl);
1796 }
1797 } else if (thread->is_VM_thread()) {
1798 if (thread->claim_oops_do(true, _thread_parity)) {
1799 JavaThread::satb_mark_queue_set().shared_satb_queue()->apply_closure_and_empty(&_cm_satb_cl);
1800 }
1801 }
1802 }
1803 };
1804
1805 class G1CMRemarkTask: public AbstractGangTask {
1806 private:
1807 G1ConcurrentMark* _cm;
1808 public:
1809 void work(uint worker_id) {
1810 // Since all available tasks are actually started, we should
1811 // only proceed if we're supposed to be active.
1812 if (worker_id < _cm->active_tasks()) {
1813 G1CMTask* task = _cm->task(worker_id);
1814 task->record_start_time();
1815 {
1816 ResourceMark rm;
1817 HandleMark hm;
1818
1819 G1RemarkThreadsClosure threads_f(G1CollectedHeap::heap(), task);
1820 Threads::threads_do(&threads_f);
1821 }
1822
1823 do {
1824 task->do_marking_step(1000000000.0 /* something very large */,
1825 true /* do_termination */,
1826 false /* is_serial */);
1827 } while (task->has_aborted() && !_cm->has_overflown());
1828 // If we overflow, then we do not want to restart. We instead
1829 // want to abort remark and do concurrent marking again.
1830 task->record_end_time();
1831 }
1832 }
1833
1834 G1CMRemarkTask(G1ConcurrentMark* cm, uint active_workers) :
1835 AbstractGangTask("Par Remark"), _cm(cm) {
1836 _cm->terminator()->reset_for_reuse(active_workers);
1837 }
1838 };
1839
1840 void G1ConcurrentMark::checkpointRootsFinalWork() {
1841 ResourceMark rm;
1842 HandleMark hm;
1843 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1844
1845 GCTraceTime(Debug, gc, phases) trace("Finalize Marking", _gc_timer_cm);
1846
1847 g1h->ensure_parsability(false);
1848
1849 // this is remark, so we'll use up all active threads
1850 uint active_workers = g1h->workers()->active_workers();
1851 set_concurrency_and_phase(active_workers, false /* concurrent */);
1852 // Leave _parallel_marking_threads at it's
1853 // value originally calculated in the G1ConcurrentMark
1854 // constructor and pass values of the active workers
1855 // through the gang in the task.
1856
1857 {
1858 StrongRootsScope srs(active_workers);
1859
1860 G1CMRemarkTask remarkTask(this, active_workers);
1861 // We will start all available threads, even if we decide that the
1862 // active_workers will be fewer. The extra ones will just bail out
1863 // immediately.
1864 g1h->workers()->run_task(&remarkTask);
1865 }
1866
1867 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
1868 guarantee(has_overflown() ||
1869 satb_mq_set.completed_buffers_num() == 0,
1870 "Invariant: has_overflown = %s, num buffers = " SIZE_FORMAT,
1871 BOOL_TO_STR(has_overflown()),
1872 satb_mq_set.completed_buffers_num());
1873
1874 print_stats();
1875 }
1876
1877 void G1ConcurrentMark::clearRangePrevBitmap(MemRegion mr) {
1878 _prevMarkBitMap->clear_range(mr);
1879 }
1880
1881 HeapRegion*
1882 G1ConcurrentMark::claim_region(uint worker_id) {
1883 // "checkpoint" the finger
1884 HeapWord* finger = _finger;
1885
1886 // _heap_end will not change underneath our feet; it only changes at
1887 // yield points.
1888 while (finger < _heap_end) {
1889 assert(_g1h->is_in_g1_reserved(finger), "invariant");
1890
1891 HeapRegion* curr_region = _g1h->heap_region_containing(finger);
1892 // Make sure that the reads below do not float before loading curr_region.
1893 OrderAccess::loadload();
1894 // Above heap_region_containing may return NULL as we always scan claim
1895 // until the end of the heap. In this case, just jump to the next region.
1896 HeapWord* end = curr_region != NULL ? curr_region->end() : finger + HeapRegion::GrainWords;
1897
1898 // Is the gap between reading the finger and doing the CAS too long?
1899 HeapWord* res = (HeapWord*) Atomic::cmpxchg_ptr(end, &_finger, finger);
1900 if (res == finger && curr_region != NULL) {
1901 // we succeeded
1902 HeapWord* bottom = curr_region->bottom();
1903 HeapWord* limit = curr_region->next_top_at_mark_start();
1904
1905 // notice that _finger == end cannot be guaranteed here since,
1906 // someone else might have moved the finger even further
1907 assert(_finger >= end, "the finger should have moved forward");
1908
1909 if (limit > bottom) {
1910 return curr_region;
1911 } else {
1912 assert(limit == bottom,
1913 "the region limit should be at bottom");
1914 // we return NULL and the caller should try calling
1915 // claim_region() again.
1916 return NULL;
1917 }
1918 } else {
1919 assert(_finger > finger, "the finger should have moved forward");
1920 // read it again
1921 finger = _finger;
1922 }
1923 }
1924
1925 return NULL;
1926 }
1927
1928 #ifndef PRODUCT
1929 class VerifyNoCSetOops VALUE_OBJ_CLASS_SPEC {
1930 private:
1931 G1CollectedHeap* _g1h;
1932 const char* _phase;
1933 int _info;
1934
1935 public:
1936 VerifyNoCSetOops(const char* phase, int info = -1) :
1937 _g1h(G1CollectedHeap::heap()),
1938 _phase(phase),
1939 _info(info)
1940 { }
1941
1942 void operator()(G1TaskQueueEntry task_entry) const {
1943 if (task_entry.is_array_slice()) {
1944 guarantee(_g1h->is_in_reserved(task_entry.slice()), "Slice " PTR_FORMAT " must be in heap.", p2i(task_entry.slice()));
1945 return;
1946 }
1947 guarantee(task_entry.obj()->is_oop(),
1948 "Non-oop " PTR_FORMAT ", phase: %s, info: %d",
1949 p2i(task_entry.obj()), _phase, _info);
1950 guarantee(!_g1h->is_in_cset(task_entry.obj()),
1951 "obj: " PTR_FORMAT " in CSet, phase: %s, info: %d",
1952 p2i(task_entry.obj()), _phase, _info);
1953 }
1954 };
1955
1956 void G1ConcurrentMark::verify_no_cset_oops() {
1957 assert(SafepointSynchronize::is_at_safepoint(), "should be at a safepoint");
1958 if (!G1CollectedHeap::heap()->collector_state()->mark_in_progress()) {
1959 return;
1960 }
1961
1962 // Verify entries on the global mark stack
1963 _global_mark_stack.iterate(VerifyNoCSetOops("Stack"));
1964
1965 // Verify entries on the task queues
1966 for (uint i = 0; i < _max_worker_id; ++i) {
1967 G1CMTaskQueue* queue = _task_queues->queue(i);
1968 queue->iterate(VerifyNoCSetOops("Queue", i));
1969 }
1970
1971 // Verify the global finger
1972 HeapWord* global_finger = finger();
1973 if (global_finger != NULL && global_finger < _heap_end) {
1974 // Since we always iterate over all regions, we might get a NULL HeapRegion
1975 // here.
1976 HeapRegion* global_hr = _g1h->heap_region_containing(global_finger);
1977 guarantee(global_hr == NULL || global_finger == global_hr->bottom(),
1978 "global finger: " PTR_FORMAT " region: " HR_FORMAT,
1979 p2i(global_finger), HR_FORMAT_PARAMS(global_hr));
1980 }
1981
1982 // Verify the task fingers
1983 assert(parallel_marking_threads() <= _max_worker_id, "sanity");
1984 for (uint i = 0; i < parallel_marking_threads(); ++i) {
1985 G1CMTask* task = _tasks[i];
1986 HeapWord* task_finger = task->finger();
1987 if (task_finger != NULL && task_finger < _heap_end) {
1988 // See above note on the global finger verification.
1989 HeapRegion* task_hr = _g1h->heap_region_containing(task_finger);
1990 guarantee(task_hr == NULL || task_finger == task_hr->bottom() ||
1991 !task_hr->in_collection_set(),
1992 "task finger: " PTR_FORMAT " region: " HR_FORMAT,
1993 p2i(task_finger), HR_FORMAT_PARAMS(task_hr));
1994 }
1995 }
1996 }
1997 #endif // PRODUCT
1998 void G1ConcurrentMark::create_live_data() {
1999 _g1h->g1_rem_set()->create_card_live_data(_parallel_workers, _nextMarkBitMap);
2000 }
2001
2002 void G1ConcurrentMark::finalize_live_data() {
2003 _g1h->g1_rem_set()->finalize_card_live_data(_g1h->workers(), _nextMarkBitMap);
2004 }
2005
2006 void G1ConcurrentMark::verify_live_data() {
2007 _g1h->g1_rem_set()->verify_card_live_data(_g1h->workers(), _nextMarkBitMap);
2008 }
2009
2010 void G1ConcurrentMark::clear_live_data(WorkGang* workers) {
2011 _g1h->g1_rem_set()->clear_card_live_data(workers);
2012 }
2013
2014 #ifdef ASSERT
2015 void G1ConcurrentMark::verify_live_data_clear() {
2016 _g1h->g1_rem_set()->verify_card_live_data_is_clear();
2017 }
2018 #endif
2019
2020 void G1ConcurrentMark::print_stats() {
2021 if (!log_is_enabled(Debug, gc, stats)) {
2022 return;
2023 }
2024 log_debug(gc, stats)("---------------------------------------------------------------------");
2025 for (size_t i = 0; i < _active_tasks; ++i) {
2026 _tasks[i]->print_stats();
2027 log_debug(gc, stats)("---------------------------------------------------------------------");
2028 }
2029 }
2030
2031 void G1ConcurrentMark::abort() {
2032 if (!cmThread()->during_cycle() || _has_aborted) {
2033 // We haven't started a concurrent cycle or we have already aborted it. No need to do anything.
2034 return;
2035 }
2036
2037 // Clear all marks in the next bitmap for the next marking cycle. This will allow us to skip the next
2038 // concurrent bitmap clearing.
2039 {
2040 GCTraceTime(Debug, gc)("Clear Next Bitmap");
2041 clear_bitmap(_nextMarkBitMap, _g1h->workers(), false);
2042 }
2043 // Note we cannot clear the previous marking bitmap here
2044 // since VerifyDuringGC verifies the objects marked during
2045 // a full GC against the previous bitmap.
2046
2047 {
2048 GCTraceTime(Debug, gc)("Clear Live Data");
2049 clear_live_data(_g1h->workers());
2050 }
2051 DEBUG_ONLY({
2052 GCTraceTime(Debug, gc)("Verify Live Data Clear");
2053 verify_live_data_clear();
2054 })
2055 // Empty mark stack
2056 reset_marking_state();
2057 for (uint i = 0; i < _max_worker_id; ++i) {
2058 _tasks[i]->clear_region_fields();
2059 }
2060 _first_overflow_barrier_sync.abort();
2061 _second_overflow_barrier_sync.abort();
2062 _has_aborted = true;
2063
2064 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
2065 satb_mq_set.abandon_partial_marking();
2066 // This can be called either during or outside marking, we'll read
2067 // the expected_active value from the SATB queue set.
2068 satb_mq_set.set_active_all_threads(
2069 false, /* new active value */
2070 satb_mq_set.is_active() /* expected_active */);
2071 }
2072
2073 static void print_ms_time_info(const char* prefix, const char* name,
2074 NumberSeq& ns) {
2075 log_trace(gc, marking)("%s%5d %12s: total time = %8.2f s (avg = %8.2f ms).",
2076 prefix, ns.num(), name, ns.sum()/1000.0, ns.avg());
2077 if (ns.num() > 0) {
2078 log_trace(gc, marking)("%s [std. dev = %8.2f ms, max = %8.2f ms]",
2079 prefix, ns.sd(), ns.maximum());
2080 }
2081 }
2082
2083 void G1ConcurrentMark::print_summary_info() {
2084 Log(gc, marking) log;
2085 if (!log.is_trace()) {
2086 return;
2087 }
2088
2089 log.trace(" Concurrent marking:");
2090 print_ms_time_info(" ", "init marks", _init_times);
2091 print_ms_time_info(" ", "remarks", _remark_times);
2092 {
2093 print_ms_time_info(" ", "final marks", _remark_mark_times);
2094 print_ms_time_info(" ", "weak refs", _remark_weak_ref_times);
2095
2096 }
2097 print_ms_time_info(" ", "cleanups", _cleanup_times);
2098 log.trace(" Finalize live data total time = %8.2f s (avg = %8.2f ms).",
2099 _total_counting_time, (_cleanup_times.num() > 0 ? _total_counting_time * 1000.0 / (double)_cleanup_times.num() : 0.0));
2100 if (G1ScrubRemSets) {
2101 log.trace(" RS scrub total time = %8.2f s (avg = %8.2f ms).",
2102 _total_rs_scrub_time, (_cleanup_times.num() > 0 ? _total_rs_scrub_time * 1000.0 / (double)_cleanup_times.num() : 0.0));
2103 }
2104 log.trace(" Total stop_world time = %8.2f s.",
2105 (_init_times.sum() + _remark_times.sum() + _cleanup_times.sum())/1000.0);
2106 log.trace(" Total concurrent time = %8.2f s (%8.2f s marking).",
2107 cmThread()->vtime_accum(), cmThread()->vtime_mark_accum());
2108 }
2109
2110 void G1ConcurrentMark::print_worker_threads_on(outputStream* st) const {
2111 _parallel_workers->print_worker_threads_on(st);
2112 }
2113
2114 void G1ConcurrentMark::threads_do(ThreadClosure* tc) const {
2115 _parallel_workers->threads_do(tc);
2116 }
2117
2118 void G1ConcurrentMark::print_on_error(outputStream* st) const {
2119 st->print_cr("Marking Bits (Prev, Next): (CMBitMap*) " PTR_FORMAT ", (CMBitMap*) " PTR_FORMAT,
2120 p2i(_prevMarkBitMap), p2i(_nextMarkBitMap));
2121 _prevMarkBitMap->print_on_error(st, " Prev Bits: ");
2122 _nextMarkBitMap->print_on_error(st, " Next Bits: ");
2123 }
2124
2125 bool G1CMBitMapClosure::do_addr(HeapWord* const addr) {
2126 assert(addr < _cm->finger(), "invariant");
2127 assert(addr >= _task->finger(), "invariant");
2128
2129 // We move that task's local finger along.
2130 _task->move_finger_to(addr);
2131
2132 _task->scan_task_entry(G1TaskQueueEntry::from_oop(oop(addr)));
2133 // we only partially drain the local queue and global stack
2134 _task->drain_local_queue(true);
2135 _task->drain_global_stack(true);
2136
2137 // if the has_aborted flag has been raised, we need to bail out of
2138 // the iteration
2139 return !_task->has_aborted();
2140 }
2141
2142 static ReferenceProcessor* get_cm_oop_closure_ref_processor(G1CollectedHeap* g1h) {
2143 ReferenceProcessor* result = g1h->ref_processor_cm();
2144 assert(result != NULL, "CM reference processor should not be NULL");
2145 return result;
2146 }
2147
2148 G1CMOopClosure::G1CMOopClosure(G1CollectedHeap* g1h,
2149 G1ConcurrentMark* cm,
2150 G1CMTask* task)
2151 : MetadataAwareOopClosure(get_cm_oop_closure_ref_processor(g1h)),
2152 _g1h(g1h), _cm(cm), _task(task)
2153 { }
2154
2155 void G1CMTask::setup_for_region(HeapRegion* hr) {
2156 assert(hr != NULL,
2157 "claim_region() should have filtered out NULL regions");
2158 _curr_region = hr;
2159 _finger = hr->bottom();
2160 update_region_limit();
2161 }
2162
2163 void G1CMTask::update_region_limit() {
2164 HeapRegion* hr = _curr_region;
2165 HeapWord* bottom = hr->bottom();
2166 HeapWord* limit = hr->next_top_at_mark_start();
2167
2168 if (limit == bottom) {
2169 // The region was collected underneath our feet.
2170 // We set the finger to bottom to ensure that the bitmap
2171 // iteration that will follow this will not do anything.
2172 // (this is not a condition that holds when we set the region up,
2173 // as the region is not supposed to be empty in the first place)
2174 _finger = bottom;
2175 } else if (limit >= _region_limit) {
2176 assert(limit >= _finger, "peace of mind");
2177 } else {
2178 assert(limit < _region_limit, "only way to get here");
2179 // This can happen under some pretty unusual circumstances. An
2180 // evacuation pause empties the region underneath our feet (NTAMS
2181 // at bottom). We then do some allocation in the region (NTAMS
2182 // stays at bottom), followed by the region being used as a GC
2183 // alloc region (NTAMS will move to top() and the objects
2184 // originally below it will be grayed). All objects now marked in
2185 // the region are explicitly grayed, if below the global finger,
2186 // and we do not need in fact to scan anything else. So, we simply
2187 // set _finger to be limit to ensure that the bitmap iteration
2188 // doesn't do anything.
2189 _finger = limit;
2190 }
2191
2192 _region_limit = limit;
2193 }
2194
2195 void G1CMTask::giveup_current_region() {
2196 assert(_curr_region != NULL, "invariant");
2197 clear_region_fields();
2198 }
2199
2200 void G1CMTask::clear_region_fields() {
2201 // Values for these three fields that indicate that we're not
2202 // holding on to a region.
2203 _curr_region = NULL;
2204 _finger = NULL;
2205 _region_limit = NULL;
2206 }
2207
2208 void G1CMTask::set_cm_oop_closure(G1CMOopClosure* cm_oop_closure) {
2209 if (cm_oop_closure == NULL) {
2210 assert(_cm_oop_closure != NULL, "invariant");
2211 } else {
2212 assert(_cm_oop_closure == NULL, "invariant");
2213 }
2214 _cm_oop_closure = cm_oop_closure;
2215 }
2216
2217 void G1CMTask::reset(G1CMBitMap* nextMarkBitMap) {
2218 guarantee(nextMarkBitMap != NULL, "invariant");
2219 _nextMarkBitMap = nextMarkBitMap;
2220 clear_region_fields();
2221
2222 _calls = 0;
2223 _elapsed_time_ms = 0.0;
2224 _termination_time_ms = 0.0;
2225 _termination_start_time_ms = 0.0;
2226 }
2227
2228 bool G1CMTask::should_exit_termination() {
2229 regular_clock_call();
2230 // This is called when we are in the termination protocol. We should
2231 // quit if, for some reason, this task wants to abort or the global
2232 // stack is not empty (this means that we can get work from it).
2233 return !_cm->mark_stack_empty() || has_aborted();
2234 }
2235
2236 void G1CMTask::reached_limit() {
2237 assert(_words_scanned >= _words_scanned_limit ||
2238 _refs_reached >= _refs_reached_limit ,
2239 "shouldn't have been called otherwise");
2240 regular_clock_call();
2241 }
2242
2243 void G1CMTask::regular_clock_call() {
2244 if (has_aborted()) return;
2245
2246 // First, we need to recalculate the words scanned and refs reached
2247 // limits for the next clock call.
2248 recalculate_limits();
2249
2250 // During the regular clock call we do the following
2251
2252 // (1) If an overflow has been flagged, then we abort.
2253 if (_cm->has_overflown()) {
2254 set_has_aborted();
2255 return;
2256 }
2257
2258 // If we are not concurrent (i.e. we're doing remark) we don't need
2259 // to check anything else. The other steps are only needed during
2260 // the concurrent marking phase.
2261 if (!concurrent()) return;
2262
2263 // (2) If marking has been aborted for Full GC, then we also abort.
2264 if (_cm->has_aborted()) {
2265 set_has_aborted();
2266 return;
2267 }
2268
2269 double curr_time_ms = os::elapsedVTime() * 1000.0;
2270
2271 // (4) We check whether we should yield. If we have to, then we abort.
2272 if (SuspendibleThreadSet::should_yield()) {
2273 // We should yield. To do this we abort the task. The caller is
2274 // responsible for yielding.
2275 set_has_aborted();
2276 return;
2277 }
2278
2279 // (5) We check whether we've reached our time quota. If we have,
2280 // then we abort.
2281 double elapsed_time_ms = curr_time_ms - _start_time_ms;
2282 if (elapsed_time_ms > _time_target_ms) {
2283 set_has_aborted();
2284 _has_timed_out = true;
2285 return;
2286 }
2287
2288 // (6) Finally, we check whether there are enough completed STAB
2289 // buffers available for processing. If there are, we abort.
2290 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
2291 if (!_draining_satb_buffers && satb_mq_set.process_completed_buffers()) {
2292 // we do need to process SATB buffers, we'll abort and restart
2293 // the marking task to do so
2294 set_has_aborted();
2295 return;
2296 }
2297 }
2298
2299 void G1CMTask::recalculate_limits() {
2300 _real_words_scanned_limit = _words_scanned + words_scanned_period;
2301 _words_scanned_limit = _real_words_scanned_limit;
2302
2303 _real_refs_reached_limit = _refs_reached + refs_reached_period;
2304 _refs_reached_limit = _real_refs_reached_limit;
2305 }
2306
2307 void G1CMTask::decrease_limits() {
2308 // This is called when we believe that we're going to do an infrequent
2309 // operation which will increase the per byte scanned cost (i.e. move
2310 // entries to/from the global stack). It basically tries to decrease the
2311 // scanning limit so that the clock is called earlier.
2312
2313 _words_scanned_limit = _real_words_scanned_limit -
2314 3 * words_scanned_period / 4;
2315 _refs_reached_limit = _real_refs_reached_limit -
2316 3 * refs_reached_period / 4;
2317 }
2318
2319 void G1CMTask::move_entries_to_global_stack() {
2320 // Local array where we'll store the entries that will be popped
2321 // from the local queue.
2322 G1TaskQueueEntry buffer[G1CMMarkStack::EntriesPerChunk];
2323
2324 size_t n = 0;
2325 G1TaskQueueEntry task_entry;
2326 while (n < G1CMMarkStack::EntriesPerChunk && _task_queue->pop_local(task_entry)) {
2327 buffer[n] = task_entry;
2328 ++n;
2329 }
2330 if (n < G1CMMarkStack::EntriesPerChunk) {
2331 buffer[n] = G1TaskQueueEntry();
2332 }
2333
2334 if (n > 0) {
2335 if (!_cm->mark_stack_push(buffer)) {
2336 set_has_aborted();
2337 }
2338 }
2339
2340 // This operation was quite expensive, so decrease the limits.
2341 decrease_limits();
2342 }
2343
2344 bool G1CMTask::get_entries_from_global_stack() {
2345 // Local array where we'll store the entries that will be popped
2346 // from the global stack.
2347 G1TaskQueueEntry buffer[G1CMMarkStack::EntriesPerChunk];
2348
2349 if (!_cm->mark_stack_pop(buffer)) {
2350 return false;
2351 }
2352
2353 // We did actually pop at least one entry.
2354 for (size_t i = 0; i < G1CMMarkStack::EntriesPerChunk; ++i) {
2355 G1TaskQueueEntry task_entry = buffer[i];
2356 if (task_entry.is_null()) {
2357 break;
2358 }
2359 assert(task_entry.is_array_slice() || task_entry.obj()->is_oop(), "Element " PTR_FORMAT " must be an array slice or oop", p2i(task_entry.obj()));
2360 bool success = _task_queue->push(task_entry);
2361 // We only call this when the local queue is empty or under a
2362 // given target limit. So, we do not expect this push to fail.
2363 assert(success, "invariant");
2364 }
2365
2366 // This operation was quite expensive, so decrease the limits
2367 decrease_limits();
2368 return true;
2369 }
2370
2371 void G1CMTask::drain_local_queue(bool partially) {
2372 if (has_aborted()) {
2373 return;
2374 }
2375
2376 // Decide what the target size is, depending whether we're going to
2377 // drain it partially (so that other tasks can steal if they run out
2378 // of things to do) or totally (at the very end).
2379 size_t target_size;
2380 if (partially) {
2381 target_size = MIN2((size_t)_task_queue->max_elems()/3, GCDrainStackTargetSize);
2382 } else {
2383 target_size = 0;
2384 }
2385
2386 if (_task_queue->size() > target_size) {
2387 G1TaskQueueEntry entry;
2388 bool ret = _task_queue->pop_local(entry);
2389 while (ret) {
2390 scan_task_entry(entry);
2391 if (_task_queue->size() <= target_size || has_aborted()) {
2392 ret = false;
2393 } else {
2394 ret = _task_queue->pop_local(entry);
2395 }
2396 }
2397 }
2398 }
2399
2400 void G1CMTask::drain_global_stack(bool partially) {
2401 if (has_aborted()) return;
2402
2403 // We have a policy to drain the local queue before we attempt to
2404 // drain the global stack.
2405 assert(partially || _task_queue->size() == 0, "invariant");
2406
2407 // Decide what the target size is, depending whether we're going to
2408 // drain it partially (so that other tasks can steal if they run out
2409 // of things to do) or totally (at the very end).
2410 // Notice that when draining the global mark stack partially, due to the racyness
2411 // of the mark stack size update we might in fact drop below the target. But,
2412 // this is not a problem.
2413 // In case of total draining, we simply process until the global mark stack is
2414 // totally empty, disregarding the size counter.
2415 if (partially) {
2416 size_t const target_size = _cm->partial_mark_stack_size_target();
2417 while (!has_aborted() && _cm->mark_stack_size() > target_size) {
2418 if (get_entries_from_global_stack()) {
2419 drain_local_queue(partially);
2420 }
2421 }
2422 } else {
2423 while (!has_aborted() && get_entries_from_global_stack()) {
2424 drain_local_queue(partially);
2425 }
2426 }
2427 }
2428
2429 // SATB Queue has several assumptions on whether to call the par or
2430 // non-par versions of the methods. this is why some of the code is
2431 // replicated. We should really get rid of the single-threaded version
2432 // of the code to simplify things.
2433 void G1CMTask::drain_satb_buffers() {
2434 if (has_aborted()) return;
2435
2436 // We set this so that the regular clock knows that we're in the
2437 // middle of draining buffers and doesn't set the abort flag when it
2438 // notices that SATB buffers are available for draining. It'd be
2439 // very counter productive if it did that. :-)
2440 _draining_satb_buffers = true;
2441
2442 G1CMSATBBufferClosure satb_cl(this, _g1h);
2443 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
2444
2445 // This keeps claiming and applying the closure to completed buffers
2446 // until we run out of buffers or we need to abort.
2447 while (!has_aborted() &&
2448 satb_mq_set.apply_closure_to_completed_buffer(&satb_cl)) {
2449 regular_clock_call();
2450 }
2451
2452 _draining_satb_buffers = false;
2453
2454 assert(has_aborted() ||
2455 concurrent() ||
2456 satb_mq_set.completed_buffers_num() == 0, "invariant");
2457
2458 // again, this was a potentially expensive operation, decrease the
2459 // limits to get the regular clock call early
2460 decrease_limits();
2461 }
2462
2463 void G1CMTask::print_stats() {
2464 log_debug(gc, stats)("Marking Stats, task = %u, calls = %d",
2465 _worker_id, _calls);
2466 log_debug(gc, stats)(" Elapsed time = %1.2lfms, Termination time = %1.2lfms",
2467 _elapsed_time_ms, _termination_time_ms);
2468 log_debug(gc, stats)(" Step Times (cum): num = %d, avg = %1.2lfms, sd = %1.2lfms",
2469 _step_times_ms.num(), _step_times_ms.avg(),
2470 _step_times_ms.sd());
2471 log_debug(gc, stats)(" max = %1.2lfms, total = %1.2lfms",
2472 _step_times_ms.maximum(), _step_times_ms.sum());
2473 }
2474
2475 bool G1ConcurrentMark::try_stealing(uint worker_id, int* hash_seed, G1TaskQueueEntry& task_entry) {
2476 return _task_queues->steal(worker_id, hash_seed, task_entry);
2477 }
2478
2479 /*****************************************************************************
2480
2481 The do_marking_step(time_target_ms, ...) method is the building
2482 block of the parallel marking framework. It can be called in parallel
2483 with other invocations of do_marking_step() on different tasks
2484 (but only one per task, obviously) and concurrently with the
2485 mutator threads, or during remark, hence it eliminates the need
2486 for two versions of the code. When called during remark, it will
2487 pick up from where the task left off during the concurrent marking
2488 phase. Interestingly, tasks are also claimable during evacuation
2489 pauses too, since do_marking_step() ensures that it aborts before
2490 it needs to yield.
2491
2492 The data structures that it uses to do marking work are the
2493 following:
2494
2495 (1) Marking Bitmap. If there are gray objects that appear only
2496 on the bitmap (this happens either when dealing with an overflow
2497 or when the initial marking phase has simply marked the roots
2498 and didn't push them on the stack), then tasks claim heap
2499 regions whose bitmap they then scan to find gray objects. A
2500 global finger indicates where the end of the last claimed region
2501 is. A local finger indicates how far into the region a task has
2502 scanned. The two fingers are used to determine how to gray an
2503 object (i.e. whether simply marking it is OK, as it will be
2504 visited by a task in the future, or whether it needs to be also
2505 pushed on a stack).
2506
2507 (2) Local Queue. The local queue of the task which is accessed
2508 reasonably efficiently by the task. Other tasks can steal from
2509 it when they run out of work. Throughout the marking phase, a
2510 task attempts to keep its local queue short but not totally
2511 empty, so that entries are available for stealing by other
2512 tasks. Only when there is no more work, a task will totally
2513 drain its local queue.
2514
2515 (3) Global Mark Stack. This handles local queue overflow. During
2516 marking only sets of entries are moved between it and the local
2517 queues, as access to it requires a mutex and more fine-grain
2518 interaction with it which might cause contention. If it
2519 overflows, then the marking phase should restart and iterate
2520 over the bitmap to identify gray objects. Throughout the marking
2521 phase, tasks attempt to keep the global mark stack at a small
2522 length but not totally empty, so that entries are available for
2523 popping by other tasks. Only when there is no more work, tasks
2524 will totally drain the global mark stack.
2525
2526 (4) SATB Buffer Queue. This is where completed SATB buffers are
2527 made available. Buffers are regularly removed from this queue
2528 and scanned for roots, so that the queue doesn't get too
2529 long. During remark, all completed buffers are processed, as
2530 well as the filled in parts of any uncompleted buffers.
2531
2532 The do_marking_step() method tries to abort when the time target
2533 has been reached. There are a few other cases when the
2534 do_marking_step() method also aborts:
2535
2536 (1) When the marking phase has been aborted (after a Full GC).
2537
2538 (2) When a global overflow (on the global stack) has been
2539 triggered. Before the task aborts, it will actually sync up with
2540 the other tasks to ensure that all the marking data structures
2541 (local queues, stacks, fingers etc.) are re-initialized so that
2542 when do_marking_step() completes, the marking phase can
2543 immediately restart.
2544
2545 (3) When enough completed SATB buffers are available. The
2546 do_marking_step() method only tries to drain SATB buffers right
2547 at the beginning. So, if enough buffers are available, the
2548 marking step aborts and the SATB buffers are processed at
2549 the beginning of the next invocation.
2550
2551 (4) To yield. when we have to yield then we abort and yield
2552 right at the end of do_marking_step(). This saves us from a lot
2553 of hassle as, by yielding we might allow a Full GC. If this
2554 happens then objects will be compacted underneath our feet, the
2555 heap might shrink, etc. We save checking for this by just
2556 aborting and doing the yield right at the end.
2557
2558 From the above it follows that the do_marking_step() method should
2559 be called in a loop (or, otherwise, regularly) until it completes.
2560
2561 If a marking step completes without its has_aborted() flag being
2562 true, it means it has completed the current marking phase (and
2563 also all other marking tasks have done so and have all synced up).
2564
2565 A method called regular_clock_call() is invoked "regularly" (in
2566 sub ms intervals) throughout marking. It is this clock method that
2567 checks all the abort conditions which were mentioned above and
2568 decides when the task should abort. A work-based scheme is used to
2569 trigger this clock method: when the number of object words the
2570 marking phase has scanned or the number of references the marking
2571 phase has visited reach a given limit. Additional invocations to
2572 the method clock have been planted in a few other strategic places
2573 too. The initial reason for the clock method was to avoid calling
2574 vtime too regularly, as it is quite expensive. So, once it was in
2575 place, it was natural to piggy-back all the other conditions on it
2576 too and not constantly check them throughout the code.
2577
2578 If do_termination is true then do_marking_step will enter its
2579 termination protocol.
2580
2581 The value of is_serial must be true when do_marking_step is being
2582 called serially (i.e. by the VMThread) and do_marking_step should
2583 skip any synchronization in the termination and overflow code.
2584 Examples include the serial remark code and the serial reference
2585 processing closures.
2586
2587 The value of is_serial must be false when do_marking_step is
2588 being called by any of the worker threads in a work gang.
2589 Examples include the concurrent marking code (CMMarkingTask),
2590 the MT remark code, and the MT reference processing closures.
2591
2592 *****************************************************************************/
2593
2594 void G1CMTask::do_marking_step(double time_target_ms,
2595 bool do_termination,
2596 bool is_serial) {
2597 assert(time_target_ms >= 1.0, "minimum granularity is 1ms");
2598 assert(concurrent() == _cm->concurrent(), "they should be the same");
2599
2600 G1Policy* g1_policy = _g1h->g1_policy();
2601 assert(_task_queues != NULL, "invariant");
2602 assert(_task_queue != NULL, "invariant");
2603 assert(_task_queues->queue(_worker_id) == _task_queue, "invariant");
2604
2605 assert(!_claimed,
2606 "only one thread should claim this task at any one time");
2607
2608 // OK, this doesn't safeguard again all possible scenarios, as it is
2609 // possible for two threads to set the _claimed flag at the same
2610 // time. But it is only for debugging purposes anyway and it will
2611 // catch most problems.
2612 _claimed = true;
2613
2614 _start_time_ms = os::elapsedVTime() * 1000.0;
2615
2616 // If do_stealing is true then do_marking_step will attempt to
2617 // steal work from the other G1CMTasks. It only makes sense to
2618 // enable stealing when the termination protocol is enabled
2619 // and do_marking_step() is not being called serially.
2620 bool do_stealing = do_termination && !is_serial;
2621
2622 double diff_prediction_ms = _g1h->g1_policy()->predictor().get_new_prediction(&_marking_step_diffs_ms);
2623 _time_target_ms = time_target_ms - diff_prediction_ms;
2624
2625 // set up the variables that are used in the work-based scheme to
2626 // call the regular clock method
2627 _words_scanned = 0;
2628 _refs_reached = 0;
2629 recalculate_limits();
2630
2631 // clear all flags
2632 clear_has_aborted();
2633 _has_timed_out = false;
2634 _draining_satb_buffers = false;
2635
2636 ++_calls;
2637
2638 // Set up the bitmap and oop closures. Anything that uses them is
2639 // eventually called from this method, so it is OK to allocate these
2640 // statically.
2641 G1CMBitMapClosure bitmap_closure(this, _cm);
2642 G1CMOopClosure cm_oop_closure(_g1h, _cm, this);
2643 set_cm_oop_closure(&cm_oop_closure);
2644
2645 if (_cm->has_overflown()) {
2646 // This can happen if the mark stack overflows during a GC pause
2647 // and this task, after a yield point, restarts. We have to abort
2648 // as we need to get into the overflow protocol which happens
2649 // right at the end of this task.
2650 set_has_aborted();
2651 }
2652
2653 // First drain any available SATB buffers. After this, we will not
2654 // look at SATB buffers before the next invocation of this method.
2655 // If enough completed SATB buffers are queued up, the regular clock
2656 // will abort this task so that it restarts.
2657 drain_satb_buffers();
2658 // ...then partially drain the local queue and the global stack
2659 drain_local_queue(true);
2660 drain_global_stack(true);
2661
2662 do {
2663 if (!has_aborted() && _curr_region != NULL) {
2664 // This means that we're already holding on to a region.
2665 assert(_finger != NULL, "if region is not NULL, then the finger "
2666 "should not be NULL either");
2667
2668 // We might have restarted this task after an evacuation pause
2669 // which might have evacuated the region we're holding on to
2670 // underneath our feet. Let's read its limit again to make sure
2671 // that we do not iterate over a region of the heap that
2672 // contains garbage (update_region_limit() will also move
2673 // _finger to the start of the region if it is found empty).
2674 update_region_limit();
2675 // We will start from _finger not from the start of the region,
2676 // as we might be restarting this task after aborting half-way
2677 // through scanning this region. In this case, _finger points to
2678 // the address where we last found a marked object. If this is a
2679 // fresh region, _finger points to start().
2680 MemRegion mr = MemRegion(_finger, _region_limit);
2681
2682 assert(!_curr_region->is_humongous() || mr.start() == _curr_region->bottom(),
2683 "humongous regions should go around loop once only");
2684
2685 // Some special cases:
2686 // If the memory region is empty, we can just give up the region.
2687 // If the current region is humongous then we only need to check
2688 // the bitmap for the bit associated with the start of the object,
2689 // scan the object if it's live, and give up the region.
2690 // Otherwise, let's iterate over the bitmap of the part of the region
2691 // that is left.
2692 // If the iteration is successful, give up the region.
2693 if (mr.is_empty()) {
2694 giveup_current_region();
2695 regular_clock_call();
2696 } else if (_curr_region->is_humongous() && mr.start() == _curr_region->bottom()) {
2697 if (_nextMarkBitMap->is_marked(mr.start())) {
2698 // The object is marked - apply the closure
2699 bitmap_closure.do_addr(mr.start());
2700 }
2701 // Even if this task aborted while scanning the humongous object
2702 // we can (and should) give up the current region.
2703 giveup_current_region();
2704 regular_clock_call();
2705 } else if (_nextMarkBitMap->iterate(&bitmap_closure, mr)) {
2706 giveup_current_region();
2707 regular_clock_call();
2708 } else {
2709 assert(has_aborted(), "currently the only way to do so");
2710 // The only way to abort the bitmap iteration is to return
2711 // false from the do_bit() method. However, inside the
2712 // do_bit() method we move the _finger to point to the
2713 // object currently being looked at. So, if we bail out, we
2714 // have definitely set _finger to something non-null.
2715 assert(_finger != NULL, "invariant");
2716
2717 // Region iteration was actually aborted. So now _finger
2718 // points to the address of the object we last scanned. If we
2719 // leave it there, when we restart this task, we will rescan
2720 // the object. It is easy to avoid this. We move the finger by
2721 // enough to point to the next possible object header.
2722 assert(_finger < _region_limit, "invariant");
2723 HeapWord* const new_finger = _finger + ((oop)_finger)->size();
2724 // Check if bitmap iteration was aborted while scanning the last object
2725 if (new_finger >= _region_limit) {
2726 giveup_current_region();
2727 } else {
2728 move_finger_to(new_finger);
2729 }
2730 }
2731 }
2732 // At this point we have either completed iterating over the
2733 // region we were holding on to, or we have aborted.
2734
2735 // We then partially drain the local queue and the global stack.
2736 // (Do we really need this?)
2737 drain_local_queue(true);
2738 drain_global_stack(true);
2739
2740 // Read the note on the claim_region() method on why it might
2741 // return NULL with potentially more regions available for
2742 // claiming and why we have to check out_of_regions() to determine
2743 // whether we're done or not.
2744 while (!has_aborted() && _curr_region == NULL && !_cm->out_of_regions()) {
2745 // We are going to try to claim a new region. We should have
2746 // given up on the previous one.
2747 // Separated the asserts so that we know which one fires.
2748 assert(_curr_region == NULL, "invariant");
2749 assert(_finger == NULL, "invariant");
2750 assert(_region_limit == NULL, "invariant");
2751 HeapRegion* claimed_region = _cm->claim_region(_worker_id);
2752 if (claimed_region != NULL) {
2753 // Yes, we managed to claim one
2754 setup_for_region(claimed_region);
2755 assert(_curr_region == claimed_region, "invariant");
2756 }
2757 // It is important to call the regular clock here. It might take
2758 // a while to claim a region if, for example, we hit a large
2759 // block of empty regions. So we need to call the regular clock
2760 // method once round the loop to make sure it's called
2761 // frequently enough.
2762 regular_clock_call();
2763 }
2764
2765 if (!has_aborted() && _curr_region == NULL) {
2766 assert(_cm->out_of_regions(),
2767 "at this point we should be out of regions");
2768 }
2769 } while ( _curr_region != NULL && !has_aborted());
2770
2771 if (!has_aborted()) {
2772 // We cannot check whether the global stack is empty, since other
2773 // tasks might be pushing objects to it concurrently.
2774 assert(_cm->out_of_regions(),
2775 "at this point we should be out of regions");
2776 // Try to reduce the number of available SATB buffers so that
2777 // remark has less work to do.
2778 drain_satb_buffers();
2779 }
2780
2781 // Since we've done everything else, we can now totally drain the
2782 // local queue and global stack.
2783 drain_local_queue(false);
2784 drain_global_stack(false);
2785
2786 // Attempt at work stealing from other task's queues.
2787 if (do_stealing && !has_aborted()) {
2788 // We have not aborted. This means that we have finished all that
2789 // we could. Let's try to do some stealing...
2790
2791 // We cannot check whether the global stack is empty, since other
2792 // tasks might be pushing objects to it concurrently.
2793 assert(_cm->out_of_regions() && _task_queue->size() == 0,
2794 "only way to reach here");
2795 while (!has_aborted()) {
2796 G1TaskQueueEntry entry;
2797 if (_cm->try_stealing(_worker_id, &_hash_seed, entry)) {
2798 scan_task_entry(entry);
2799
2800 // And since we're towards the end, let's totally drain the
2801 // local queue and global stack.
2802 drain_local_queue(false);
2803 drain_global_stack(false);
2804 } else {
2805 break;
2806 }
2807 }
2808 }
2809
2810 // We still haven't aborted. Now, let's try to get into the
2811 // termination protocol.
2812 if (do_termination && !has_aborted()) {
2813 // We cannot check whether the global stack is empty, since other
2814 // tasks might be concurrently pushing objects on it.
2815 // Separated the asserts so that we know which one fires.
2816 assert(_cm->out_of_regions(), "only way to reach here");
2817 assert(_task_queue->size() == 0, "only way to reach here");
2818 _termination_start_time_ms = os::elapsedVTime() * 1000.0;
2819
2820 // The G1CMTask class also extends the TerminatorTerminator class,
2821 // hence its should_exit_termination() method will also decide
2822 // whether to exit the termination protocol or not.
2823 bool finished = (is_serial ||
2824 _cm->terminator()->offer_termination(this));
2825 double termination_end_time_ms = os::elapsedVTime() * 1000.0;
2826 _termination_time_ms +=
2827 termination_end_time_ms - _termination_start_time_ms;
2828
2829 if (finished) {
2830 // We're all done.
2831
2832 if (_worker_id == 0) {
2833 // let's allow task 0 to do this
2834 if (concurrent()) {
2835 assert(_cm->concurrent_marking_in_progress(), "invariant");
2836 // we need to set this to false before the next
2837 // safepoint. This way we ensure that the marking phase
2838 // doesn't observe any more heap expansions.
2839 _cm->clear_concurrent_marking_in_progress();
2840 }
2841 }
2842
2843 // We can now guarantee that the global stack is empty, since
2844 // all other tasks have finished. We separated the guarantees so
2845 // that, if a condition is false, we can immediately find out
2846 // which one.
2847 guarantee(_cm->out_of_regions(), "only way to reach here");
2848 guarantee(_cm->mark_stack_empty(), "only way to reach here");
2849 guarantee(_task_queue->size() == 0, "only way to reach here");
2850 guarantee(!_cm->has_overflown(), "only way to reach here");
2851 } else {
2852 // Apparently there's more work to do. Let's abort this task. It
2853 // will restart it and we can hopefully find more things to do.
2854 set_has_aborted();
2855 }
2856 }
2857
2858 // Mainly for debugging purposes to make sure that a pointer to the
2859 // closure which was statically allocated in this frame doesn't
2860 // escape it by accident.
2861 set_cm_oop_closure(NULL);
2862 double end_time_ms = os::elapsedVTime() * 1000.0;
2863 double elapsed_time_ms = end_time_ms - _start_time_ms;
2864 // Update the step history.
2865 _step_times_ms.add(elapsed_time_ms);
2866
2867 if (has_aborted()) {
2868 // The task was aborted for some reason.
2869 if (_has_timed_out) {
2870 double diff_ms = elapsed_time_ms - _time_target_ms;
2871 // Keep statistics of how well we did with respect to hitting
2872 // our target only if we actually timed out (if we aborted for
2873 // other reasons, then the results might get skewed).
2874 _marking_step_diffs_ms.add(diff_ms);
2875 }
2876
2877 if (_cm->has_overflown()) {
2878 // This is the interesting one. We aborted because a global
2879 // overflow was raised. This means we have to restart the
2880 // marking phase and start iterating over regions. However, in
2881 // order to do this we have to make sure that all tasks stop
2882 // what they are doing and re-initialize in a safe manner. We
2883 // will achieve this with the use of two barrier sync points.
2884
2885 if (!is_serial) {
2886 // We only need to enter the sync barrier if being called
2887 // from a parallel context
2888 _cm->enter_first_sync_barrier(_worker_id);
2889
2890 // When we exit this sync barrier we know that all tasks have
2891 // stopped doing marking work. So, it's now safe to
2892 // re-initialize our data structures. At the end of this method,
2893 // task 0 will clear the global data structures.
2894 }
2895
2896 // We clear the local state of this task...
2897 clear_region_fields();
2898
2899 if (!is_serial) {
2900 // ...and enter the second barrier.
2901 _cm->enter_second_sync_barrier(_worker_id);
2902 }
2903 // At this point, if we're during the concurrent phase of
2904 // marking, everything has been re-initialized and we're
2905 // ready to restart.
2906 }
2907 }
2908
2909 _claimed = false;
2910 }
2911
2912 G1CMTask::G1CMTask(uint worker_id,
2913 G1ConcurrentMark* cm,
2914 G1CMTaskQueue* task_queue,
2915 G1CMTaskQueueSet* task_queues)
2916 : _g1h(G1CollectedHeap::heap()),
2917 _worker_id(worker_id), _cm(cm),
2918 _objArray_processor(this),
2919 _claimed(false),
2920 _nextMarkBitMap(NULL), _hash_seed(17),
2921 _task_queue(task_queue),
2922 _task_queues(task_queues),
2923 _cm_oop_closure(NULL) {
2924 guarantee(task_queue != NULL, "invariant");
2925 guarantee(task_queues != NULL, "invariant");
2926
2927 _marking_step_diffs_ms.add(0.5);
2928 }
2929
2930 // These are formatting macros that are used below to ensure
2931 // consistent formatting. The *_H_* versions are used to format the
2932 // header for a particular value and they should be kept consistent
2933 // with the corresponding macro. Also note that most of the macros add
2934 // the necessary white space (as a prefix) which makes them a bit
2935 // easier to compose.
2936
2937 // All the output lines are prefixed with this string to be able to
2938 // identify them easily in a large log file.
2939 #define G1PPRL_LINE_PREFIX "###"
2940
2941 #define G1PPRL_ADDR_BASE_FORMAT " " PTR_FORMAT "-" PTR_FORMAT
2942 #ifdef _LP64
2943 #define G1PPRL_ADDR_BASE_H_FORMAT " %37s"
2944 #else // _LP64
2945 #define G1PPRL_ADDR_BASE_H_FORMAT " %21s"
2946 #endif // _LP64
2947
2948 // For per-region info
2949 #define G1PPRL_TYPE_FORMAT " %-4s"
2950 #define G1PPRL_TYPE_H_FORMAT " %4s"
2951 #define G1PPRL_BYTE_FORMAT " " SIZE_FORMAT_W(9)
2952 #define G1PPRL_BYTE_H_FORMAT " %9s"
2953 #define G1PPRL_DOUBLE_FORMAT " %14.1f"
2954 #define G1PPRL_DOUBLE_H_FORMAT " %14s"
2955
2956 // For summary info
2957 #define G1PPRL_SUM_ADDR_FORMAT(tag) " " tag ":" G1PPRL_ADDR_BASE_FORMAT
2958 #define G1PPRL_SUM_BYTE_FORMAT(tag) " " tag ": " SIZE_FORMAT
2959 #define G1PPRL_SUM_MB_FORMAT(tag) " " tag ": %1.2f MB"
2960 #define G1PPRL_SUM_MB_PERC_FORMAT(tag) G1PPRL_SUM_MB_FORMAT(tag) " / %1.2f %%"
2961
2962 G1PrintRegionLivenessInfoClosure::
2963 G1PrintRegionLivenessInfoClosure(const char* phase_name)
2964 : _total_used_bytes(0), _total_capacity_bytes(0),
2965 _total_prev_live_bytes(0), _total_next_live_bytes(0),
2966 _total_remset_bytes(0), _total_strong_code_roots_bytes(0) {
2967 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2968 MemRegion g1_reserved = g1h->g1_reserved();
2969 double now = os::elapsedTime();
2970
2971 // Print the header of the output.
2972 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX" PHASE %s @ %1.3f", phase_name, now);
2973 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX" HEAP"
2974 G1PPRL_SUM_ADDR_FORMAT("reserved")
2975 G1PPRL_SUM_BYTE_FORMAT("region-size"),
2976 p2i(g1_reserved.start()), p2i(g1_reserved.end()),
2977 HeapRegion::GrainBytes);
2978 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX);
2979 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX
2980 G1PPRL_TYPE_H_FORMAT
2981 G1PPRL_ADDR_BASE_H_FORMAT
2982 G1PPRL_BYTE_H_FORMAT
2983 G1PPRL_BYTE_H_FORMAT
2984 G1PPRL_BYTE_H_FORMAT
2985 G1PPRL_DOUBLE_H_FORMAT
2986 G1PPRL_BYTE_H_FORMAT
2987 G1PPRL_BYTE_H_FORMAT,
2988 "type", "address-range",
2989 "used", "prev-live", "next-live", "gc-eff",
2990 "remset", "code-roots");
2991 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX
2992 G1PPRL_TYPE_H_FORMAT
2993 G1PPRL_ADDR_BASE_H_FORMAT
2994 G1PPRL_BYTE_H_FORMAT
2995 G1PPRL_BYTE_H_FORMAT
2996 G1PPRL_BYTE_H_FORMAT
2997 G1PPRL_DOUBLE_H_FORMAT
2998 G1PPRL_BYTE_H_FORMAT
2999 G1PPRL_BYTE_H_FORMAT,
3000 "", "",
3001 "(bytes)", "(bytes)", "(bytes)", "(bytes/ms)",
3002 "(bytes)", "(bytes)");
3003 }
3004
3005 bool G1PrintRegionLivenessInfoClosure::doHeapRegion(HeapRegion* r) {
3006 const char* type = r->get_type_str();
3007 HeapWord* bottom = r->bottom();
3008 HeapWord* end = r->end();
3009 size_t capacity_bytes = r->capacity();
3010 size_t used_bytes = r->used();
3011 size_t prev_live_bytes = r->live_bytes();
3012 size_t next_live_bytes = r->next_live_bytes();
3013 double gc_eff = r->gc_efficiency();
3014 size_t remset_bytes = r->rem_set()->mem_size();
3015 size_t strong_code_roots_bytes = r->rem_set()->strong_code_roots_mem_size();
3016
3017 _total_used_bytes += used_bytes;
3018 _total_capacity_bytes += capacity_bytes;
3019 _total_prev_live_bytes += prev_live_bytes;
3020 _total_next_live_bytes += next_live_bytes;
3021 _total_remset_bytes += remset_bytes;
3022 _total_strong_code_roots_bytes += strong_code_roots_bytes;
3023
3024 // Print a line for this particular region.
3025 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX
3026 G1PPRL_TYPE_FORMAT
3027 G1PPRL_ADDR_BASE_FORMAT
3028 G1PPRL_BYTE_FORMAT
3029 G1PPRL_BYTE_FORMAT
3030 G1PPRL_BYTE_FORMAT
3031 G1PPRL_DOUBLE_FORMAT
3032 G1PPRL_BYTE_FORMAT
3033 G1PPRL_BYTE_FORMAT,
3034 type, p2i(bottom), p2i(end),
3035 used_bytes, prev_live_bytes, next_live_bytes, gc_eff,
3036 remset_bytes, strong_code_roots_bytes);
3037
3038 return false;
3039 }
3040
3041 G1PrintRegionLivenessInfoClosure::~G1PrintRegionLivenessInfoClosure() {
3042 // add static memory usages to remembered set sizes
3043 _total_remset_bytes += HeapRegionRemSet::fl_mem_size() + HeapRegionRemSet::static_mem_size();
3044 // Print the footer of the output.
3045 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX);
3046 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX
3047 " SUMMARY"
3048 G1PPRL_SUM_MB_FORMAT("capacity")
3049 G1PPRL_SUM_MB_PERC_FORMAT("used")
3050 G1PPRL_SUM_MB_PERC_FORMAT("prev-live")
3051 G1PPRL_SUM_MB_PERC_FORMAT("next-live")
3052 G1PPRL_SUM_MB_FORMAT("remset")
3053 G1PPRL_SUM_MB_FORMAT("code-roots"),
3054 bytes_to_mb(_total_capacity_bytes),
3055 bytes_to_mb(_total_used_bytes),
3056 perc(_total_used_bytes, _total_capacity_bytes),
3057 bytes_to_mb(_total_prev_live_bytes),
3058 perc(_total_prev_live_bytes, _total_capacity_bytes),
3059 bytes_to_mb(_total_next_live_bytes),
3060 perc(_total_next_live_bytes, _total_capacity_bytes),
3061 bytes_to_mb(_total_remset_bytes),
3062 bytes_to_mb(_total_strong_code_roots_bytes));
3063 }