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/shared/gcId.hpp"
42 #include "gc/shared/gcTimer.hpp"
43 #include "gc/shared/gcTrace.hpp"
44 #include "gc/shared/gcTraceTime.inline.hpp"
45 #include "gc/shared/genOopClosures.inline.hpp"
46 #include "gc/shared/referencePolicy.hpp"
47 #include "gc/shared/strongRootsScope.hpp"
48 #include "gc/shared/suspendibleThreadSet.hpp"
49 #include "gc/shared/taskqueue.inline.hpp"
50 #include "gc/shared/vmGCOperations.hpp"
51 #include "gc/shared/weakProcessor.hpp"
52 #include "logging/log.hpp"
53 #include "memory/allocation.hpp"
54 #include "memory/resourceArea.hpp"
55 #include "oops/oop.inline.hpp"
56 #include "runtime/atomic.hpp"
57 #include "runtime/handles.inline.hpp"
58 #include "runtime/java.hpp"
59 #include "runtime/prefetch.inline.hpp"
60 #include "services/memTracker.hpp"
61 #include "utilities/align.hpp"
62 #include "utilities/growableArray.hpp"
63
64 bool G1CMBitMapClosure::do_addr(HeapWord* const addr) {
65 assert(addr < _cm->finger(), "invariant");
66 assert(addr >= _task->finger(), "invariant");
67
68 // We move that task's local finger along.
69 _task->move_finger_to(addr);
70
71 _task->scan_task_entry(G1TaskQueueEntry::from_oop(oop(addr)));
72 // we only partially drain the local queue and global stack
73 _task->drain_local_queue(true);
74 _task->drain_global_stack(true);
75
76 // if the has_aborted flag has been raised, we need to bail out of
77 // the iteration
78 return !_task->has_aborted();
79 }
80
81 G1CMMarkStack::G1CMMarkStack() :
82 _max_chunk_capacity(0),
83 _base(NULL),
84 _chunk_capacity(0) {
85 set_empty();
86 }
87
88 bool G1CMMarkStack::resize(size_t new_capacity) {
89 assert(is_empty(), "Only resize when stack is empty.");
90 assert(new_capacity <= _max_chunk_capacity,
91 "Trying to resize stack to " SIZE_FORMAT " chunks when the maximum is " SIZE_FORMAT, new_capacity, _max_chunk_capacity);
92
93 TaskQueueEntryChunk* new_base = MmapArrayAllocator<TaskQueueEntryChunk>::allocate_or_null(new_capacity, mtGC);
94
95 if (new_base == NULL) {
96 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));
97 return false;
98 }
99 // Release old mapping.
100 if (_base != NULL) {
101 MmapArrayAllocator<TaskQueueEntryChunk>::free(_base, _chunk_capacity);
102 }
103
104 _base = new_base;
105 _chunk_capacity = new_capacity;
106 set_empty();
107
108 return true;
109 }
110
111 size_t G1CMMarkStack::capacity_alignment() {
112 return (size_t)lcm(os::vm_allocation_granularity(), sizeof(TaskQueueEntryChunk)) / sizeof(G1TaskQueueEntry);
113 }
114
115 bool G1CMMarkStack::initialize(size_t initial_capacity, size_t max_capacity) {
116 guarantee(_max_chunk_capacity == 0, "G1CMMarkStack already initialized.");
117
118 size_t const TaskEntryChunkSizeInVoidStar = sizeof(TaskQueueEntryChunk) / sizeof(G1TaskQueueEntry);
119
120 _max_chunk_capacity = align_up(max_capacity, capacity_alignment()) / TaskEntryChunkSizeInVoidStar;
121 size_t initial_chunk_capacity = align_up(initial_capacity, capacity_alignment()) / TaskEntryChunkSizeInVoidStar;
122
123 guarantee(initial_chunk_capacity <= _max_chunk_capacity,
124 "Maximum chunk capacity " SIZE_FORMAT " smaller than initial capacity " SIZE_FORMAT,
125 _max_chunk_capacity,
126 initial_chunk_capacity);
127
128 log_debug(gc)("Initialize mark stack with " SIZE_FORMAT " chunks, maximum " SIZE_FORMAT,
129 initial_chunk_capacity, _max_chunk_capacity);
130
131 return resize(initial_chunk_capacity);
132 }
133
134 void G1CMMarkStack::expand() {
135 if (_chunk_capacity == _max_chunk_capacity) {
136 log_debug(gc)("Can not expand overflow mark stack further, already at maximum capacity of " SIZE_FORMAT " chunks.", _chunk_capacity);
137 return;
138 }
139 size_t old_capacity = _chunk_capacity;
140 // Double capacity if possible
141 size_t new_capacity = MIN2(old_capacity * 2, _max_chunk_capacity);
142
143 if (resize(new_capacity)) {
144 log_debug(gc)("Expanded mark stack capacity from " SIZE_FORMAT " to " SIZE_FORMAT " chunks",
145 old_capacity, new_capacity);
146 } else {
147 log_warning(gc)("Failed to expand mark stack capacity from " SIZE_FORMAT " to " SIZE_FORMAT " chunks",
148 old_capacity, new_capacity);
149 }
150 }
151
152 G1CMMarkStack::~G1CMMarkStack() {
153 if (_base != NULL) {
154 MmapArrayAllocator<TaskQueueEntryChunk>::free(_base, _chunk_capacity);
155 }
156 }
157
158 void G1CMMarkStack::add_chunk_to_list(TaskQueueEntryChunk* volatile* list, TaskQueueEntryChunk* elem) {
159 elem->next = *list;
160 *list = elem;
161 }
162
163 void G1CMMarkStack::add_chunk_to_chunk_list(TaskQueueEntryChunk* elem) {
164 MutexLockerEx x(MarkStackChunkList_lock, Mutex::_no_safepoint_check_flag);
165 add_chunk_to_list(&_chunk_list, elem);
166 _chunks_in_chunk_list++;
167 }
168
169 void G1CMMarkStack::add_chunk_to_free_list(TaskQueueEntryChunk* elem) {
170 MutexLockerEx x(MarkStackFreeList_lock, Mutex::_no_safepoint_check_flag);
171 add_chunk_to_list(&_free_list, elem);
172 }
173
174 G1CMMarkStack::TaskQueueEntryChunk* G1CMMarkStack::remove_chunk_from_list(TaskQueueEntryChunk* volatile* list) {
175 TaskQueueEntryChunk* result = *list;
176 if (result != NULL) {
177 *list = (*list)->next;
178 }
179 return result;
180 }
181
182 G1CMMarkStack::TaskQueueEntryChunk* G1CMMarkStack::remove_chunk_from_chunk_list() {
183 MutexLockerEx x(MarkStackChunkList_lock, Mutex::_no_safepoint_check_flag);
184 TaskQueueEntryChunk* result = remove_chunk_from_list(&_chunk_list);
185 if (result != NULL) {
186 _chunks_in_chunk_list--;
187 }
188 return result;
189 }
190
191 G1CMMarkStack::TaskQueueEntryChunk* G1CMMarkStack::remove_chunk_from_free_list() {
192 MutexLockerEx x(MarkStackFreeList_lock, Mutex::_no_safepoint_check_flag);
193 return remove_chunk_from_list(&_free_list);
194 }
195
196 G1CMMarkStack::TaskQueueEntryChunk* G1CMMarkStack::allocate_new_chunk() {
197 // This dirty read of _hwm is okay because we only ever increase the _hwm in parallel code.
198 // Further this limits _hwm to a value of _chunk_capacity + #threads, avoiding
199 // wraparound of _hwm.
200 if (_hwm >= _chunk_capacity) {
201 return NULL;
202 }
203
204 size_t cur_idx = Atomic::add(1u, &_hwm) - 1;
205 if (cur_idx >= _chunk_capacity) {
206 return NULL;
207 }
208
209 TaskQueueEntryChunk* result = ::new (&_base[cur_idx]) TaskQueueEntryChunk;
210 result->next = NULL;
211 return result;
212 }
213
214 bool G1CMMarkStack::par_push_chunk(G1TaskQueueEntry* ptr_arr) {
215 // Get a new chunk.
216 TaskQueueEntryChunk* new_chunk = remove_chunk_from_free_list();
217
218 if (new_chunk == NULL) {
219 // Did not get a chunk from the free list. Allocate from backing memory.
220 new_chunk = allocate_new_chunk();
221
222 if (new_chunk == NULL) {
223 return false;
224 }
225 }
226
227 Copy::conjoint_memory_atomic(ptr_arr, new_chunk->data, EntriesPerChunk * sizeof(G1TaskQueueEntry));
228
229 add_chunk_to_chunk_list(new_chunk);
230
231 return true;
232 }
233
234 bool G1CMMarkStack::par_pop_chunk(G1TaskQueueEntry* ptr_arr) {
235 TaskQueueEntryChunk* cur = remove_chunk_from_chunk_list();
236
237 if (cur == NULL) {
238 return false;
239 }
240
241 Copy::conjoint_memory_atomic(cur->data, ptr_arr, EntriesPerChunk * sizeof(G1TaskQueueEntry));
242
243 add_chunk_to_free_list(cur);
244 return true;
245 }
246
247 void G1CMMarkStack::set_empty() {
248 _chunks_in_chunk_list = 0;
249 _hwm = 0;
250 _chunk_list = NULL;
251 _free_list = NULL;
252 }
253
254 G1CMRootRegions::G1CMRootRegions() :
255 _cm(NULL), _scan_in_progress(false),
256 _should_abort(false), _claimed_survivor_index(0) { }
257
258 void G1CMRootRegions::init(const G1SurvivorRegions* survivors, G1ConcurrentMark* cm) {
259 _survivors = survivors;
260 _cm = cm;
261 }
262
263 void G1CMRootRegions::prepare_for_scan() {
264 assert(!scan_in_progress(), "pre-condition");
265
266 // Currently, only survivors can be root regions.
267 _claimed_survivor_index = 0;
268 _scan_in_progress = _survivors->regions()->is_nonempty();
269 _should_abort = false;
270 }
271
272 HeapRegion* G1CMRootRegions::claim_next() {
273 if (_should_abort) {
274 // If someone has set the should_abort flag, we return NULL to
275 // force the caller to bail out of their loop.
276 return NULL;
277 }
278
279 // Currently, only survivors can be root regions.
280 const GrowableArray<HeapRegion*>* survivor_regions = _survivors->regions();
281
282 int claimed_index = Atomic::add(1, &_claimed_survivor_index) - 1;
283 if (claimed_index < survivor_regions->length()) {
284 return survivor_regions->at(claimed_index);
285 }
286 return NULL;
287 }
288
289 uint G1CMRootRegions::num_root_regions() const {
290 return (uint)_survivors->regions()->length();
291 }
292
293 void G1CMRootRegions::notify_scan_done() {
294 MutexLockerEx x(RootRegionScan_lock, Mutex::_no_safepoint_check_flag);
295 _scan_in_progress = false;
296 RootRegionScan_lock->notify_all();
297 }
298
299 void G1CMRootRegions::cancel_scan() {
300 notify_scan_done();
301 }
302
303 void G1CMRootRegions::scan_finished() {
304 assert(scan_in_progress(), "pre-condition");
305
306 // Currently, only survivors can be root regions.
307 if (!_should_abort) {
308 assert(_claimed_survivor_index >= 0, "otherwise comparison is invalid: %d", _claimed_survivor_index);
309 assert((uint)_claimed_survivor_index >= _survivors->length(),
310 "we should have claimed all survivors, claimed index = %u, length = %u",
311 (uint)_claimed_survivor_index, _survivors->length());
312 }
313
314 notify_scan_done();
315 }
316
317 bool G1CMRootRegions::wait_until_scan_finished() {
318 if (!scan_in_progress()) return false;
319
320 {
321 MutexLockerEx x(RootRegionScan_lock, Mutex::_no_safepoint_check_flag);
322 while (scan_in_progress()) {
323 RootRegionScan_lock->wait(Mutex::_no_safepoint_check_flag);
324 }
325 }
326 return true;
327 }
328
329 // Returns the maximum number of workers to be used in a concurrent
330 // phase based on the number of GC workers being used in a STW
331 // phase.
332 static uint scale_concurrent_worker_threads(uint num_gc_workers) {
333 return MAX2((num_gc_workers + 2) / 4, 1U);
334 }
335
336 G1ConcurrentMark::G1ConcurrentMark(G1CollectedHeap* g1h,
337 G1RegionToSpaceMapper* prev_bitmap_storage,
338 G1RegionToSpaceMapper* next_bitmap_storage) :
339 // _cm_thread set inside the constructor
340 _g1h(g1h),
341 _completed_initialization(false),
342
343 _cleanup_list("Concurrent Mark Cleanup List"),
344 _mark_bitmap_1(),
345 _mark_bitmap_2(),
346 _prev_mark_bitmap(&_mark_bitmap_1),
347 _next_mark_bitmap(&_mark_bitmap_2),
348
349 _heap_start(_g1h->reserved_region().start()),
350 _heap_end(_g1h->reserved_region().end()),
351
352 _root_regions(),
353
354 _global_mark_stack(),
355
356 // _finger set in set_non_marking_state
357
358 _max_num_tasks(ParallelGCThreads),
359 // _num_active_tasks set in set_non_marking_state()
360 // _tasks set inside the constructor
361
362 _task_queues(new G1CMTaskQueueSet((int) _max_num_tasks)),
363 _terminator(ParallelTaskTerminator((int) _max_num_tasks, _task_queues)),
364
365 _first_overflow_barrier_sync(),
366 _second_overflow_barrier_sync(),
367
368 _has_overflown(false),
369 _concurrent(false),
370 _has_aborted(false),
371 _restart_for_overflow(false),
372 _concurrent_marking_in_progress(false),
373 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
374 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()),
375
376 // _verbose_level set below
377
378 _init_times(),
379 _remark_times(),
380 _remark_mark_times(),
381 _remark_weak_ref_times(),
382 _cleanup_times(),
383 _total_counting_time(0.0),
384 _total_rs_scrub_time(0.0),
385
386 _accum_task_vtime(NULL),
387
388 _concurrent_workers(NULL),
389 _num_concurrent_workers(0),
390 _max_concurrent_workers(0)
391 {
392 _mark_bitmap_1.initialize(g1h->reserved_region(), prev_bitmap_storage);
393 _mark_bitmap_2.initialize(g1h->reserved_region(), next_bitmap_storage);
394
395 // Create & start ConcurrentMark thread.
396 _cm_thread = new ConcurrentMarkThread(this);
397 if (_cm_thread->osthread() == NULL) {
398 vm_shutdown_during_initialization("Could not create ConcurrentMarkThread");
399 }
400
401 assert(CGC_lock != NULL, "CGC_lock must be initialized");
402
403 SATBMarkQueueSet& satb_qs = JavaThread::satb_mark_queue_set();
404 satb_qs.set_buffer_size(G1SATBBufferSize);
405
406 _root_regions.init(_g1h->survivor(), this);
407
408 if (FLAG_IS_DEFAULT(ConcGCThreads) || ConcGCThreads == 0) {
409 // Calculate the number of concurrent worker threads by scaling
410 // the number of parallel GC threads.
411 uint marking_thread_num = scale_concurrent_worker_threads(ParallelGCThreads);
412 FLAG_SET_ERGO(uint, ConcGCThreads, marking_thread_num);
413 }
414
415 assert(ConcGCThreads > 0, "ConcGCThreads have been set.");
416 if (ConcGCThreads > ParallelGCThreads) {
417 log_warning(gc)("More ConcGCThreads (%u) than ParallelGCThreads (%u).",
418 ConcGCThreads, ParallelGCThreads);
419 return;
420 }
421
422 log_debug(gc)("ConcGCThreads: %u", ConcGCThreads);
423 log_debug(gc)("ParallelGCThreads: %u", ParallelGCThreads);
424
425 _num_concurrent_workers = ConcGCThreads;
426 _max_concurrent_workers = _num_concurrent_workers;
427
428 _concurrent_workers = new WorkGang("G1 Conc", _max_concurrent_workers, false, true);
429 _concurrent_workers->initialize_workers();
430
431 if (FLAG_IS_DEFAULT(MarkStackSize)) {
432 size_t mark_stack_size =
433 MIN2(MarkStackSizeMax,
434 MAX2(MarkStackSize, (size_t) (_max_concurrent_workers * TASKQUEUE_SIZE)));
435 // Verify that the calculated value for MarkStackSize is in range.
436 // It would be nice to use the private utility routine from Arguments.
437 if (!(mark_stack_size >= 1 && mark_stack_size <= MarkStackSizeMax)) {
438 log_warning(gc)("Invalid value calculated for MarkStackSize (" SIZE_FORMAT "): "
439 "must be between 1 and " SIZE_FORMAT,
440 mark_stack_size, MarkStackSizeMax);
441 return;
442 }
443 FLAG_SET_ERGO(size_t, MarkStackSize, mark_stack_size);
444 } else {
445 // Verify MarkStackSize is in range.
446 if (FLAG_IS_CMDLINE(MarkStackSize)) {
447 if (FLAG_IS_DEFAULT(MarkStackSizeMax)) {
448 if (!(MarkStackSize >= 1 && MarkStackSize <= MarkStackSizeMax)) {
449 log_warning(gc)("Invalid value specified for MarkStackSize (" SIZE_FORMAT "): "
450 "must be between 1 and " SIZE_FORMAT,
451 MarkStackSize, MarkStackSizeMax);
452 return;
453 }
454 } else if (FLAG_IS_CMDLINE(MarkStackSizeMax)) {
455 if (!(MarkStackSize >= 1 && MarkStackSize <= MarkStackSizeMax)) {
456 log_warning(gc)("Invalid value specified for MarkStackSize (" SIZE_FORMAT ")"
457 " or for MarkStackSizeMax (" SIZE_FORMAT ")",
458 MarkStackSize, MarkStackSizeMax);
459 return;
460 }
461 }
462 }
463 }
464
465 if (!_global_mark_stack.initialize(MarkStackSize, MarkStackSizeMax)) {
466 vm_exit_during_initialization("Failed to allocate initial concurrent mark overflow mark stack.");
467 }
468
469 _tasks = NEW_C_HEAP_ARRAY(G1CMTask*, _max_num_tasks, mtGC);
470 _accum_task_vtime = NEW_C_HEAP_ARRAY(double, _max_num_tasks, mtGC);
471
472 // so that the assertion in MarkingTaskQueue::task_queue doesn't fail
473 _num_active_tasks = _max_num_tasks;
474
475 for (uint i = 0; i < _max_num_tasks; ++i) {
476 G1CMTaskQueue* task_queue = new G1CMTaskQueue();
477 task_queue->initialize();
478 _task_queues->register_queue(i, task_queue);
479
480 _tasks[i] = new G1CMTask(i, this, task_queue);
481
482 _accum_task_vtime[i] = 0.0;
483 }
484
485 set_non_marking_state();
486 _completed_initialization = true;
487 }
488
489 void G1ConcurrentMark::reset() {
490 // Starting values for these two. This should be called in a STW
491 // phase.
492 MemRegion reserved = _g1h->g1_reserved();
493 _heap_start = reserved.start();
494 _heap_end = reserved.end();
495
496 // Separated the asserts so that we know which one fires.
497 assert(_heap_start != NULL, "heap bounds should look ok");
498 assert(_heap_end != NULL, "heap bounds should look ok");
499 assert(_heap_start < _heap_end, "heap bounds should look ok");
500
501 // Reset all the marking data structures and any necessary flags
502 reset_marking_state();
503
504 // We reset all of them, since different phases will use
505 // different number of active threads. So, it's easiest to have all
506 // of them ready.
507 for (uint i = 0; i < _max_num_tasks; ++i) {
508 _tasks[i]->reset(_next_mark_bitmap);
509 }
510
511 // we need this to make sure that the flag is on during the evac
512 // pause with initial mark piggy-backed
513 set_concurrent_marking_in_progress();
514 }
515
516
517 void G1ConcurrentMark::reset_marking_state() {
518 _global_mark_stack.set_empty();
519
520 // Expand the marking stack, if we have to and if we can.
521 if (has_overflown()) {
522 _global_mark_stack.expand();
523 }
524
525 clear_has_overflown();
526 _finger = _heap_start;
527
528 for (uint i = 0; i < _max_num_tasks; ++i) {
529 G1CMTaskQueue* queue = _task_queues->queue(i);
530 queue->set_empty();
531 }
532 }
533
534 void G1ConcurrentMark::set_concurrency(uint active_tasks) {
535 assert(active_tasks <= _max_num_tasks, "we should not have more");
536
537 _num_active_tasks = active_tasks;
538 // Need to update the three data structures below according to the
539 // number of active threads for this phase.
540 _terminator = ParallelTaskTerminator((int) active_tasks, _task_queues);
541 _first_overflow_barrier_sync.set_n_workers((int) active_tasks);
542 _second_overflow_barrier_sync.set_n_workers((int) active_tasks);
543 }
544
545 void G1ConcurrentMark::set_concurrency_and_phase(uint active_tasks, bool concurrent) {
546 set_concurrency(active_tasks);
547
548 _concurrent = concurrent;
549 // We propagate this to all tasks, not just the active ones.
550 for (uint i = 0; i < _max_num_tasks; ++i) {
551 _tasks[i]->set_concurrent(concurrent);
552 }
553
554 if (concurrent) {
555 set_concurrent_marking_in_progress();
556 } else {
557 // We currently assume that the concurrent flag has been set to
558 // false before we start remark. At this point we should also be
559 // in a STW phase.
560 assert(!concurrent_marking_in_progress(), "invariant");
561 assert(out_of_regions(),
562 "only way to get here: _finger: " PTR_FORMAT ", _heap_end: " PTR_FORMAT,
563 p2i(_finger), p2i(_heap_end));
564 }
565 }
566
567 void G1ConcurrentMark::set_non_marking_state() {
568 // We set the global marking state to some default values when we're
569 // not doing marking.
570 reset_marking_state();
571 _num_active_tasks = 0;
572 clear_concurrent_marking_in_progress();
573 }
574
575 G1ConcurrentMark::~G1ConcurrentMark() {
576 // The G1ConcurrentMark instance is never freed.
577 ShouldNotReachHere();
578 }
579
580 class G1ClearBitMapTask : public AbstractGangTask {
581 public:
582 static size_t chunk_size() { return M; }
583
584 private:
585 // Heap region closure used for clearing the given mark bitmap.
586 class G1ClearBitmapHRClosure : public HeapRegionClosure {
587 private:
588 G1CMBitMap* _bitmap;
589 G1ConcurrentMark* _cm;
590 public:
591 G1ClearBitmapHRClosure(G1CMBitMap* bitmap, G1ConcurrentMark* cm) : HeapRegionClosure(), _cm(cm), _bitmap(bitmap) {
592 }
593
594 virtual bool doHeapRegion(HeapRegion* r) {
595 size_t const chunk_size_in_words = G1ClearBitMapTask::chunk_size() / HeapWordSize;
596
597 HeapWord* cur = r->bottom();
598 HeapWord* const end = r->end();
599
600 while (cur < end) {
601 MemRegion mr(cur, MIN2(cur + chunk_size_in_words, end));
602 _bitmap->clear_range(mr);
603
604 cur += chunk_size_in_words;
605
606 // Abort iteration if after yielding the marking has been aborted.
607 if (_cm != NULL && _cm->do_yield_check() && _cm->has_aborted()) {
608 return true;
609 }
610 // Repeat the asserts from before the start of the closure. We will do them
611 // as asserts here to minimize their overhead on the product. However, we
612 // will have them as guarantees at the beginning / end of the bitmap
613 // clearing to get some checking in the product.
614 assert(_cm == NULL || _cm->cm_thread()->during_cycle(), "invariant");
615 assert(_cm == NULL || !G1CollectedHeap::heap()->collector_state()->mark_in_progress(), "invariant");
616 }
617 assert(cur == end, "Must have completed iteration over the bitmap for region %u.", r->hrm_index());
618
619 return false;
620 }
621 };
622
623 G1ClearBitmapHRClosure _cl;
624 HeapRegionClaimer _hr_claimer;
625 bool _suspendible; // If the task is suspendible, workers must join the STS.
626
627 public:
628 G1ClearBitMapTask(G1CMBitMap* bitmap, G1ConcurrentMark* cm, uint n_workers, bool suspendible) :
629 AbstractGangTask("G1 Clear Bitmap"),
630 _cl(bitmap, suspendible ? cm : NULL),
631 _hr_claimer(n_workers),
632 _suspendible(suspendible)
633 { }
634
635 void work(uint worker_id) {
636 SuspendibleThreadSetJoiner sts_join(_suspendible);
637 G1CollectedHeap::heap()->heap_region_par_iterate_from_worker_offset(&_cl, &_hr_claimer, worker_id);
638 }
639
640 bool is_complete() {
641 return _cl.complete();
642 }
643 };
644
645 void G1ConcurrentMark::clear_bitmap(G1CMBitMap* bitmap, WorkGang* workers, bool may_yield) {
646 assert(may_yield || SafepointSynchronize::is_at_safepoint(), "Non-yielding bitmap clear only allowed at safepoint.");
647
648 size_t const num_bytes_to_clear = (HeapRegion::GrainBytes * _g1h->num_regions()) / G1CMBitMap::heap_map_factor();
649 size_t const num_chunks = align_up(num_bytes_to_clear, G1ClearBitMapTask::chunk_size()) / G1ClearBitMapTask::chunk_size();
650
651 uint const num_workers = (uint)MIN2(num_chunks, (size_t)workers->active_workers());
652
653 G1ClearBitMapTask cl(bitmap, this, num_workers, may_yield);
654
655 log_debug(gc, ergo)("Running %s with %u workers for " SIZE_FORMAT " work units.", cl.name(), num_workers, num_chunks);
656 workers->run_task(&cl, num_workers);
657 guarantee(!may_yield || cl.is_complete(), "Must have completed iteration when not yielding.");
658 }
659
660 void G1ConcurrentMark::cleanup_for_next_mark() {
661 // Make sure that the concurrent mark thread looks to still be in
662 // the current cycle.
663 guarantee(cm_thread()->during_cycle(), "invariant");
664
665 // We are finishing up the current cycle by clearing the next
666 // marking bitmap and getting it ready for the next cycle. During
667 // this time no other cycle can start. So, let's make sure that this
668 // is the case.
669 guarantee(!_g1h->collector_state()->mark_in_progress(), "invariant");
670
671 clear_bitmap(_next_mark_bitmap, _concurrent_workers, true);
672
673 // Clear the live count data. If the marking has been aborted, the abort()
674 // call already did that.
675 if (!has_aborted()) {
676 clear_live_data(_concurrent_workers);
677 DEBUG_ONLY(verify_live_data_clear());
678 }
679
680 // Repeat the asserts from above.
681 guarantee(cm_thread()->during_cycle(), "invariant");
682 guarantee(!_g1h->collector_state()->mark_in_progress(), "invariant");
683 }
684
685 void G1ConcurrentMark::clear_prev_bitmap(WorkGang* workers) {
686 assert(SafepointSynchronize::is_at_safepoint(), "Should only clear the entire prev bitmap at a safepoint.");
687 clear_bitmap(_prev_mark_bitmap, workers, false);
688 }
689
690 class CheckBitmapClearHRClosure : public HeapRegionClosure {
691 G1CMBitMap* _bitmap;
692 bool _error;
693 public:
694 CheckBitmapClearHRClosure(G1CMBitMap* bitmap) : _bitmap(bitmap) {
695 }
696
697 virtual bool doHeapRegion(HeapRegion* r) {
698 // This closure can be called concurrently to the mutator, so we must make sure
699 // that the result of the getNextMarkedWordAddress() call is compared to the
700 // value passed to it as limit to detect any found bits.
701 // end never changes in G1.
702 HeapWord* end = r->end();
703 return _bitmap->get_next_marked_addr(r->bottom(), end) != end;
704 }
705 };
706
707 bool G1ConcurrentMark::next_mark_bitmap_is_clear() {
708 CheckBitmapClearHRClosure cl(_next_mark_bitmap);
709 _g1h->heap_region_iterate(&cl);
710 return cl.complete();
711 }
712
713 class NoteStartOfMarkHRClosure: public HeapRegionClosure {
714 public:
715 bool doHeapRegion(HeapRegion* r) {
716 r->note_start_of_marking();
717 return false;
718 }
719 };
720
721 void G1ConcurrentMark::checkpoint_roots_initial_pre() {
722 G1CollectedHeap* g1h = G1CollectedHeap::heap();
723
724 _has_aborted = false;
725
726 // Initialize marking structures. This has to be done in a STW phase.
727 reset();
728
729 // For each region note start of marking.
730 NoteStartOfMarkHRClosure startcl;
731 g1h->heap_region_iterate(&startcl);
732 }
733
734
735 void G1ConcurrentMark::checkpoint_roots_initial_post() {
736 G1CollectedHeap* g1h = G1CollectedHeap::heap();
737
738 // Start Concurrent Marking weak-reference discovery.
739 ReferenceProcessor* rp = g1h->ref_processor_cm();
740 // enable ("weak") refs discovery
741 rp->enable_discovery();
742 rp->setup_policy(false); // snapshot the soft ref policy to be used in this cycle
743
744 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
745 // This is the start of the marking cycle, we're expected all
746 // threads to have SATB queues with active set to false.
747 satb_mq_set.set_active_all_threads(true, /* new active value */
748 false /* expected_active */);
749
750 _root_regions.prepare_for_scan();
751
752 // update_g1_committed() will be called at the end of an evac pause
753 // when marking is on. So, it's also called at the end of the
754 // initial-mark pause to update the heap end, if the heap expands
755 // during it. No need to call it here.
756 }
757
758 /*
759 * Notice that in the next two methods, we actually leave the STS
760 * during the barrier sync and join it immediately afterwards. If we
761 * do not do this, the following deadlock can occur: one thread could
762 * be in the barrier sync code, waiting for the other thread to also
763 * sync up, whereas another one could be trying to yield, while also
764 * waiting for the other threads to sync up too.
765 *
766 * Note, however, that this code is also used during remark and in
767 * this case we should not attempt to leave / enter the STS, otherwise
768 * we'll either hit an assert (debug / fastdebug) or deadlock
769 * (product). So we should only leave / enter the STS if we are
770 * operating concurrently.
771 *
772 * Because the thread that does the sync barrier has left the STS, it
773 * is possible to be suspended for a Full GC or an evacuation pause
774 * could occur. This is actually safe, since the entering the sync
775 * barrier is one of the last things do_marking_step() does, and it
776 * doesn't manipulate any data structures afterwards.
777 */
778
779 void G1ConcurrentMark::enter_first_sync_barrier(uint worker_id) {
780 bool barrier_aborted;
781 {
782 SuspendibleThreadSetLeaver sts_leave(concurrent());
783 barrier_aborted = !_first_overflow_barrier_sync.enter();
784 }
785
786 // at this point everyone should have synced up and not be doing any
787 // more work
788
789 if (barrier_aborted) {
790 // If the barrier aborted we ignore the overflow condition and
791 // just abort the whole marking phase as quickly as possible.
792 return;
793 }
794
795 // If we're executing the concurrent phase of marking, reset the marking
796 // state; otherwise the marking state is reset after reference processing,
797 // during the remark pause.
798 // If we reset here as a result of an overflow during the remark we will
799 // see assertion failures from any subsequent set_concurrency_and_phase()
800 // calls.
801 if (concurrent()) {
802 // let the task associated with with worker 0 do this
803 if (worker_id == 0) {
804 // task 0 is responsible for clearing the global data structures
805 // We should be here because of an overflow. During STW we should
806 // not clear the overflow flag since we rely on it being true when
807 // we exit this method to abort the pause and restart concurrent
808 // marking.
809 reset_marking_state();
810
811 log_info(gc, marking)("Concurrent Mark reset for overflow");
812 }
813 }
814
815 // after this, each task should reset its own data structures then
816 // then go into the second barrier
817 }
818
819 void G1ConcurrentMark::enter_second_sync_barrier(uint worker_id) {
820 SuspendibleThreadSetLeaver sts_leave(concurrent());
821 _second_overflow_barrier_sync.enter();
822
823 // at this point everything should be re-initialized and ready to go
824 }
825
826 class G1CMConcurrentMarkingTask: public AbstractGangTask {
827 private:
828 G1ConcurrentMark* _cm;
829 ConcurrentMarkThread* _cmt;
830
831 public:
832 void work(uint worker_id) {
833 assert(Thread::current()->is_ConcurrentGC_thread(), "Not a concurrent GC thread");
834 ResourceMark rm;
835
836 double start_vtime = os::elapsedVTime();
837
838 {
839 SuspendibleThreadSetJoiner sts_join;
840
841 assert(worker_id < _cm->active_tasks(), "invariant");
842
843 G1CMTask* task = _cm->task(worker_id);
844 task->record_start_time();
845 if (!_cm->has_aborted()) {
846 do {
847 task->do_marking_step(G1ConcMarkStepDurationMillis,
848 true /* do_termination */,
849 false /* is_serial*/);
850
851 _cm->do_yield_check();
852 } while (!_cm->has_aborted() && task->has_aborted());
853 }
854 task->record_end_time();
855 guarantee(!task->has_aborted() || _cm->has_aborted(), "invariant");
856 }
857
858 double end_vtime = os::elapsedVTime();
859 _cm->update_accum_task_vtime(worker_id, end_vtime - start_vtime);
860 }
861
862 G1CMConcurrentMarkingTask(G1ConcurrentMark* cm,
863 ConcurrentMarkThread* cmt) :
864 AbstractGangTask("Concurrent Mark"), _cm(cm), _cmt(cmt) { }
865
866 ~G1CMConcurrentMarkingTask() { }
867 };
868
869 uint G1ConcurrentMark::calc_active_marking_workers() {
870 uint result = 0;
871 if (!UseDynamicNumberOfGCThreads ||
872 (!FLAG_IS_DEFAULT(ConcGCThreads) &&
873 !ForceDynamicNumberOfGCThreads)) {
874 result = _max_concurrent_workers;
875 } else {
876 result =
877 AdaptiveSizePolicy::calc_default_active_workers(_max_concurrent_workers,
878 1, /* Minimum workers */
879 _num_concurrent_workers,
880 Threads::number_of_non_daemon_threads());
881 // Don't scale the result down by scale_concurrent_workers() because
882 // that scaling has already gone into "_max_concurrent_workers".
883 }
884 assert(result > 0 && result <= _max_concurrent_workers,
885 "Calculated number of marking workers must be larger than zero and at most the maximum %u, but is %u",
886 _max_concurrent_workers, result);
887 return result;
888 }
889
890 void G1ConcurrentMark::scan_root_region(HeapRegion* hr) {
891 // Currently, only survivors can be root regions.
892 assert(hr->next_top_at_mark_start() == hr->bottom(), "invariant");
893 G1RootRegionScanClosure cl(_g1h, this);
894
895 const uintx interval = PrefetchScanIntervalInBytes;
896 HeapWord* curr = hr->bottom();
897 const HeapWord* end = hr->top();
898 while (curr < end) {
899 Prefetch::read(curr, interval);
900 oop obj = oop(curr);
901 int size = obj->oop_iterate_size(&cl);
902 assert(size == obj->size(), "sanity");
903 curr += size;
904 }
905 }
906
907 class G1CMRootRegionScanTask : public AbstractGangTask {
908 private:
909 G1ConcurrentMark* _cm;
910
911 public:
912 G1CMRootRegionScanTask(G1ConcurrentMark* cm) :
913 AbstractGangTask("G1 Root Region Scan"), _cm(cm) { }
914
915 void work(uint worker_id) {
916 assert(Thread::current()->is_ConcurrentGC_thread(),
917 "this should only be done by a conc GC thread");
918
919 G1CMRootRegions* root_regions = _cm->root_regions();
920 HeapRegion* hr = root_regions->claim_next();
921 while (hr != NULL) {
922 _cm->scan_root_region(hr);
923 hr = root_regions->claim_next();
924 }
925 }
926 };
927
928 void G1ConcurrentMark::scan_root_regions() {
929 // scan_in_progress() will have been set to true only if there was
930 // at least one root region to scan. So, if it's false, we
931 // should not attempt to do any further work.
932 if (root_regions()->scan_in_progress()) {
933 assert(!has_aborted(), "Aborting before root region scanning is finished not supported.");
934
935 _num_concurrent_workers = MIN2(calc_active_marking_workers(),
936 // We distribute work on a per-region basis, so starting
937 // more threads than that is useless.
938 root_regions()->num_root_regions());
939 assert(_num_concurrent_workers <= _max_concurrent_workers,
940 "Maximum number of marking threads exceeded");
941
942 G1CMRootRegionScanTask task(this);
943 log_debug(gc, ergo)("Running %s using %u workers for %u work units.",
944 task.name(), _num_concurrent_workers, root_regions()->num_root_regions());
945 _concurrent_workers->run_task(&task, _num_concurrent_workers);
946
947 // It's possible that has_aborted() is true here without actually
948 // aborting the survivor scan earlier. This is OK as it's
949 // mainly used for sanity checking.
950 root_regions()->scan_finished();
951 }
952 }
953
954 void G1ConcurrentMark::concurrent_cycle_start() {
955 _gc_timer_cm->register_gc_start();
956
957 _gc_tracer_cm->report_gc_start(GCCause::_no_gc /* first parameter is not used */, _gc_timer_cm->gc_start());
958
959 _g1h->trace_heap_before_gc(_gc_tracer_cm);
960 }
961
962 void G1ConcurrentMark::concurrent_cycle_end() {
963 _g1h->trace_heap_after_gc(_gc_tracer_cm);
964
965 if (has_aborted()) {
966 _gc_tracer_cm->report_concurrent_mode_failure();
967 }
968
969 _gc_timer_cm->register_gc_end();
970
971 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
972 }
973
974 void G1ConcurrentMark::mark_from_roots() {
975 // we might be tempted to assert that:
976 // assert(asynch == !SafepointSynchronize::is_at_safepoint(),
977 // "inconsistent argument?");
978 // However that wouldn't be right, because it's possible that
979 // a safepoint is indeed in progress as a younger generation
980 // stop-the-world GC happens even as we mark in this generation.
981
982 _restart_for_overflow = false;
983
984 _num_concurrent_workers = calc_active_marking_workers();
985
986 uint active_workers = MAX2(1U, _num_concurrent_workers);
987
988 // Setting active workers is not guaranteed since fewer
989 // worker threads may currently exist and more may not be
990 // available.
991 active_workers = _concurrent_workers->update_active_workers(active_workers);
992 log_info(gc, task)("Using %u workers of %u for marking", active_workers, _concurrent_workers->total_workers());
993
994 // Parallel task terminator is set in "set_concurrency_and_phase()"
995 set_concurrency_and_phase(active_workers, true /* concurrent */);
996
997 G1CMConcurrentMarkingTask marking_task(this, cm_thread());
998 _concurrent_workers->run_task(&marking_task);
999 print_stats();
1000 }
1001
1002 void G1ConcurrentMark::checkpoint_roots_final(bool clear_all_soft_refs) {
1003 // world is stopped at this checkpoint
1004 assert(SafepointSynchronize::is_at_safepoint(),
1005 "world should be stopped");
1006
1007 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1008
1009 // If a full collection has happened, we shouldn't do this.
1010 if (has_aborted()) {
1011 g1h->collector_state()->set_mark_in_progress(false); // So bitmap clearing isn't confused
1012 return;
1013 }
1014
1015 SvcGCMarker sgcm(SvcGCMarker::OTHER);
1016
1017 if (VerifyDuringGC) {
1018 HandleMark hm; // handle scope
1019 g1h->prepare_for_verify();
1020 Universe::verify(VerifyOption_G1UsePrevMarking, "During GC (before)");
1021 }
1022 g1h->verifier()->check_bitmaps("Remark Start");
1023
1024 G1Policy* g1p = g1h->g1_policy();
1025 g1p->record_concurrent_mark_remark_start();
1026
1027 double start = os::elapsedTime();
1028
1029 checkpoint_roots_final_work();
1030
1031 double mark_work_end = os::elapsedTime();
1032
1033 weak_refs_work(clear_all_soft_refs);
1034
1035 if (has_overflown()) {
1036 // We overflowed. Restart concurrent marking.
1037 _restart_for_overflow = true;
1038
1039 // Verify the heap w.r.t. the previous marking bitmap.
1040 if (VerifyDuringGC) {
1041 HandleMark hm; // handle scope
1042 g1h->prepare_for_verify();
1043 Universe::verify(VerifyOption_G1UsePrevMarking, "During GC (overflow)");
1044 }
1045
1046 // Clear the marking state because we will be restarting
1047 // marking due to overflowing the global mark stack.
1048 reset_marking_state();
1049 } else {
1050 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
1051 // We're done with marking.
1052 // This is the end of the marking cycle, we're expected all
1053 // threads to have SATB queues with active set to true.
1054 satb_mq_set.set_active_all_threads(false, /* new active value */
1055 true /* expected_active */);
1056
1057 if (VerifyDuringGC) {
1058 HandleMark hm; // handle scope
1059 g1h->prepare_for_verify();
1060 Universe::verify(VerifyOption_G1UseNextMarking, "During GC (after)");
1061 }
1062 g1h->verifier()->check_bitmaps("Remark End");
1063 assert(!restart_for_overflow(), "sanity");
1064 // Completely reset the marking state since marking completed
1065 set_non_marking_state();
1066 }
1067
1068 // Statistics
1069 double now = os::elapsedTime();
1070 _remark_mark_times.add((mark_work_end - start) * 1000.0);
1071 _remark_weak_ref_times.add((now - mark_work_end) * 1000.0);
1072 _remark_times.add((now - start) * 1000.0);
1073
1074 g1p->record_concurrent_mark_remark_end();
1075
1076 G1CMIsAliveClosure is_alive(g1h);
1077 _gc_tracer_cm->report_object_count_after_gc(&is_alive);
1078 }
1079
1080 class G1NoteEndOfConcMarkClosure : public HeapRegionClosure {
1081 G1CollectedHeap* _g1;
1082 size_t _freed_bytes;
1083 FreeRegionList* _local_cleanup_list;
1084 uint _old_regions_removed;
1085 uint _humongous_regions_removed;
1086 HRRSCleanupTask* _hrrs_cleanup_task;
1087
1088 public:
1089 G1NoteEndOfConcMarkClosure(G1CollectedHeap* g1,
1090 FreeRegionList* local_cleanup_list,
1091 HRRSCleanupTask* hrrs_cleanup_task) :
1092 _g1(g1),
1093 _freed_bytes(0),
1094 _local_cleanup_list(local_cleanup_list),
1095 _old_regions_removed(0),
1096 _humongous_regions_removed(0),
1097 _hrrs_cleanup_task(hrrs_cleanup_task) { }
1098
1099 size_t freed_bytes() { return _freed_bytes; }
1100 const uint old_regions_removed() { return _old_regions_removed; }
1101 const uint humongous_regions_removed() { return _humongous_regions_removed; }
1102
1103 bool doHeapRegion(HeapRegion *hr) {
1104 _g1->reset_gc_time_stamps(hr);
1105 hr->note_end_of_marking();
1106
1107 if (hr->used() > 0 && hr->max_live_bytes() == 0 && !hr->is_young() && !hr->is_archive()) {
1108 _freed_bytes += hr->used();
1109 hr->set_containing_set(NULL);
1110 if (hr->is_humongous()) {
1111 _humongous_regions_removed++;
1112 _g1->free_humongous_region(hr, _local_cleanup_list, true /* skip_remset */);
1113 } else {
1114 _old_regions_removed++;
1115 _g1->free_region(hr, _local_cleanup_list, true /* skip_remset */);
1116 }
1117 } else {
1118 hr->rem_set()->do_cleanup_work(_hrrs_cleanup_task);
1119 }
1120
1121 return false;
1122 }
1123 };
1124
1125 class G1ParNoteEndTask: public AbstractGangTask {
1126 friend class G1NoteEndOfConcMarkClosure;
1127
1128 protected:
1129 G1CollectedHeap* _g1h;
1130 FreeRegionList* _cleanup_list;
1131 HeapRegionClaimer _hrclaimer;
1132
1133 public:
1134 G1ParNoteEndTask(G1CollectedHeap* g1h, FreeRegionList* cleanup_list, uint n_workers) :
1135 AbstractGangTask("G1 note end"), _g1h(g1h), _cleanup_list(cleanup_list), _hrclaimer(n_workers) {
1136 }
1137
1138 void work(uint worker_id) {
1139 FreeRegionList local_cleanup_list("Local Cleanup List");
1140 HRRSCleanupTask hrrs_cleanup_task;
1141 G1NoteEndOfConcMarkClosure g1_note_end(_g1h, &local_cleanup_list,
1142 &hrrs_cleanup_task);
1143 _g1h->heap_region_par_iterate_from_worker_offset(&g1_note_end, &_hrclaimer, worker_id);
1144 assert(g1_note_end.complete(), "Shouldn't have yielded!");
1145
1146 // Now update the lists
1147 _g1h->remove_from_old_sets(g1_note_end.old_regions_removed(), g1_note_end.humongous_regions_removed());
1148 {
1149 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
1150 _g1h->decrement_summary_bytes(g1_note_end.freed_bytes());
1151
1152 // If we iterate over the global cleanup list at the end of
1153 // cleanup to do this printing we will not guarantee to only
1154 // generate output for the newly-reclaimed regions (the list
1155 // might not be empty at the beginning of cleanup; we might
1156 // still be working on its previous contents). So we do the
1157 // printing here, before we append the new regions to the global
1158 // cleanup list.
1159
1160 G1HRPrinter* hr_printer = _g1h->hr_printer();
1161 if (hr_printer->is_active()) {
1162 FreeRegionListIterator iter(&local_cleanup_list);
1163 while (iter.more_available()) {
1164 HeapRegion* hr = iter.get_next();
1165 hr_printer->cleanup(hr);
1166 }
1167 }
1168
1169 _cleanup_list->add_ordered(&local_cleanup_list);
1170 assert(local_cleanup_list.is_empty(), "post-condition");
1171
1172 HeapRegionRemSet::finish_cleanup_task(&hrrs_cleanup_task);
1173 }
1174 }
1175 };
1176
1177 void G1ConcurrentMark::cleanup() {
1178 // world is stopped at this checkpoint
1179 assert(SafepointSynchronize::is_at_safepoint(),
1180 "world should be stopped");
1181 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1182
1183 // If a full collection has happened, we shouldn't do this.
1184 if (has_aborted()) {
1185 g1h->collector_state()->set_mark_in_progress(false); // So bitmap clearing isn't confused
1186 return;
1187 }
1188
1189 g1h->verifier()->verify_region_sets_optional();
1190
1191 if (VerifyDuringGC) {
1192 HandleMark hm; // handle scope
1193 g1h->prepare_for_verify();
1194 Universe::verify(VerifyOption_G1UsePrevMarking, "During GC (before)");
1195 }
1196 g1h->verifier()->check_bitmaps("Cleanup Start");
1197
1198 G1Policy* g1p = g1h->g1_policy();
1199 g1p->record_concurrent_mark_cleanup_start();
1200
1201 double start = os::elapsedTime();
1202
1203 HeapRegionRemSet::reset_for_cleanup_tasks();
1204
1205 {
1206 GCTraceTime(Debug, gc)("Finalize Live Data");
1207 finalize_live_data();
1208 }
1209
1210 if (VerifyDuringGC) {
1211 GCTraceTime(Debug, gc)("Verify Live Data");
1212 verify_live_data();
1213 }
1214
1215 g1h->collector_state()->set_mark_in_progress(false);
1216
1217 double count_end = os::elapsedTime();
1218 double this_final_counting_time = (count_end - start);
1219 _total_counting_time += this_final_counting_time;
1220
1221 if (log_is_enabled(Trace, gc, liveness)) {
1222 G1PrintRegionLivenessInfoClosure cl("Post-Marking");
1223 _g1h->heap_region_iterate(&cl);
1224 }
1225
1226 // Install newly created mark bitMap as "prev".
1227 swap_mark_bitmaps();
1228
1229 g1h->reset_gc_time_stamp();
1230
1231 uint n_workers = _g1h->workers()->active_workers();
1232
1233 // Note end of marking in all heap regions.
1234 G1ParNoteEndTask g1_par_note_end_task(g1h, &_cleanup_list, n_workers);
1235 g1h->workers()->run_task(&g1_par_note_end_task);
1236 g1h->check_gc_time_stamps();
1237
1238 if (!cleanup_list_is_empty()) {
1239 // The cleanup list is not empty, so we'll have to process it
1240 // concurrently. Notify anyone else that might be wanting free
1241 // regions that there will be more free regions coming soon.
1242 g1h->set_free_regions_coming();
1243 }
1244
1245 // call below, since it affects the metric by which we sort the heap
1246 // regions.
1247 if (G1ScrubRemSets) {
1248 double rs_scrub_start = os::elapsedTime();
1249 g1h->scrub_rem_set();
1250 _total_rs_scrub_time += (os::elapsedTime() - rs_scrub_start);
1251 }
1252
1253 // this will also free any regions totally full of garbage objects,
1254 // and sort the regions.
1255 g1h->g1_policy()->record_concurrent_mark_cleanup_end();
1256
1257 // Statistics.
1258 double end = os::elapsedTime();
1259 _cleanup_times.add((end - start) * 1000.0);
1260
1261 // Clean up will have freed any regions completely full of garbage.
1262 // Update the soft reference policy with the new heap occupancy.
1263 Universe::update_heap_info_at_gc();
1264
1265 if (VerifyDuringGC) {
1266 HandleMark hm; // handle scope
1267 g1h->prepare_for_verify();
1268 Universe::verify(VerifyOption_G1UsePrevMarking, "During GC (after)");
1269 }
1270
1271 g1h->verifier()->check_bitmaps("Cleanup End");
1272
1273 g1h->verifier()->verify_region_sets_optional();
1274
1275 // We need to make this be a "collection" so any collection pause that
1276 // races with it goes around and waits for completeCleanup to finish.
1277 g1h->increment_total_collections();
1278
1279 // Clean out dead classes and update Metaspace sizes.
1280 if (ClassUnloadingWithConcurrentMark) {
1281 ClassLoaderDataGraph::purge();
1282 }
1283 MetaspaceGC::compute_new_size();
1284
1285 // We reclaimed old regions so we should calculate the sizes to make
1286 // sure we update the old gen/space data.
1287 g1h->g1mm()->update_sizes();
1288 g1h->allocation_context_stats().update_after_mark();
1289 }
1290
1291 void G1ConcurrentMark::complete_cleanup() {
1292 if (has_aborted()) return;
1293
1294 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1295
1296 _cleanup_list.verify_optional();
1297 FreeRegionList tmp_free_list("Tmp Free List");
1298
1299 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [complete cleanup] : "
1300 "cleanup list has %u entries",
1301 _cleanup_list.length());
1302
1303 // No one else should be accessing the _cleanup_list at this point,
1304 // so it is not necessary to take any locks
1305 while (!_cleanup_list.is_empty()) {
1306 HeapRegion* hr = _cleanup_list.remove_region(true /* from_head */);
1307 assert(hr != NULL, "Got NULL from a non-empty list");
1308 hr->par_clear();
1309 tmp_free_list.add_ordered(hr);
1310
1311 // Instead of adding one region at a time to the secondary_free_list,
1312 // we accumulate them in the local list and move them a few at a
1313 // time. This also cuts down on the number of notify_all() calls
1314 // we do during this process. We'll also append the local list when
1315 // _cleanup_list is empty (which means we just removed the last
1316 // region from the _cleanup_list).
1317 if ((tmp_free_list.length() % G1SecondaryFreeListAppendLength == 0) ||
1318 _cleanup_list.is_empty()) {
1319 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [complete cleanup] : "
1320 "appending %u entries to the secondary_free_list, "
1321 "cleanup list still has %u entries",
1322 tmp_free_list.length(),
1323 _cleanup_list.length());
1324
1325 {
1326 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
1327 g1h->secondary_free_list_add(&tmp_free_list);
1328 SecondaryFreeList_lock->notify_all();
1329 }
1330 #ifndef PRODUCT
1331 if (G1StressConcRegionFreeing) {
1332 for (uintx i = 0; i < G1StressConcRegionFreeingDelayMillis; ++i) {
1333 os::sleep(Thread::current(), (jlong) 1, false);
1334 }
1335 }
1336 #endif
1337 }
1338 }
1339 assert(tmp_free_list.is_empty(), "post-condition");
1340 }
1341
1342 // Supporting Object and Oop closures for reference discovery
1343 // and processing in during marking
1344
1345 bool G1CMIsAliveClosure::do_object_b(oop obj) {
1346 HeapWord* addr = (HeapWord*)obj;
1347 return addr != NULL &&
1348 (!_g1->is_in_g1_reserved(addr) || !_g1->is_obj_ill(obj));
1349 }
1350
1351 // 'Keep Alive' oop closure used by both serial parallel reference processing.
1352 // Uses the G1CMTask associated with a worker thread (for serial reference
1353 // processing the G1CMTask for worker 0 is used) to preserve (mark) and
1354 // trace referent objects.
1355 //
1356 // Using the G1CMTask and embedded local queues avoids having the worker
1357 // threads operating on the global mark stack. This reduces the risk
1358 // of overflowing the stack - which we would rather avoid at this late
1359 // state. Also using the tasks' local queues removes the potential
1360 // of the workers interfering with each other that could occur if
1361 // operating on the global stack.
1362
1363 class G1CMKeepAliveAndDrainClosure: public OopClosure {
1364 G1ConcurrentMark* _cm;
1365 G1CMTask* _task;
1366 int _ref_counter_limit;
1367 int _ref_counter;
1368 bool _is_serial;
1369 public:
1370 G1CMKeepAliveAndDrainClosure(G1ConcurrentMark* cm, G1CMTask* task, bool is_serial) :
1371 _cm(cm), _task(task), _is_serial(is_serial),
1372 _ref_counter_limit(G1RefProcDrainInterval) {
1373 assert(_ref_counter_limit > 0, "sanity");
1374 assert(!_is_serial || _task->worker_id() == 0, "only task 0 for serial code");
1375 _ref_counter = _ref_counter_limit;
1376 }
1377
1378 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
1379 virtual void do_oop( oop* p) { do_oop_work(p); }
1380
1381 template <class T> void do_oop_work(T* p) {
1382 if (!_cm->has_overflown()) {
1383 oop obj = oopDesc::load_decode_heap_oop(p);
1384 _task->deal_with_reference(obj);
1385 _ref_counter--;
1386
1387 if (_ref_counter == 0) {
1388 // We have dealt with _ref_counter_limit references, pushing them
1389 // and objects reachable from them on to the local stack (and
1390 // possibly the global stack). Call G1CMTask::do_marking_step() to
1391 // process these entries.
1392 //
1393 // We call G1CMTask::do_marking_step() in a loop, which we'll exit if
1394 // there's nothing more to do (i.e. we're done with the entries that
1395 // were pushed as a result of the G1CMTask::deal_with_reference() calls
1396 // above) or we overflow.
1397 //
1398 // Note: G1CMTask::do_marking_step() can set the G1CMTask::has_aborted()
1399 // flag while there may still be some work to do. (See the comment at
1400 // the beginning of G1CMTask::do_marking_step() for those conditions -
1401 // one of which is reaching the specified time target.) It is only
1402 // when G1CMTask::do_marking_step() returns without setting the
1403 // has_aborted() flag that the marking step has completed.
1404 do {
1405 double mark_step_duration_ms = G1ConcMarkStepDurationMillis;
1406 _task->do_marking_step(mark_step_duration_ms,
1407 false /* do_termination */,
1408 _is_serial);
1409 } while (_task->has_aborted() && !_cm->has_overflown());
1410 _ref_counter = _ref_counter_limit;
1411 }
1412 }
1413 }
1414 };
1415
1416 // 'Drain' oop closure used by both serial and parallel reference processing.
1417 // Uses the G1CMTask associated with a given worker thread (for serial
1418 // reference processing the G1CMtask for worker 0 is used). Calls the
1419 // do_marking_step routine, with an unbelievably large timeout value,
1420 // to drain the marking data structures of the remaining entries
1421 // added by the 'keep alive' oop closure above.
1422
1423 class G1CMDrainMarkingStackClosure: public VoidClosure {
1424 G1ConcurrentMark* _cm;
1425 G1CMTask* _task;
1426 bool _is_serial;
1427 public:
1428 G1CMDrainMarkingStackClosure(G1ConcurrentMark* cm, G1CMTask* task, bool is_serial) :
1429 _cm(cm), _task(task), _is_serial(is_serial) {
1430 assert(!_is_serial || _task->worker_id() == 0, "only task 0 for serial code");
1431 }
1432
1433 void do_void() {
1434 do {
1435 // We call G1CMTask::do_marking_step() to completely drain the local
1436 // and global marking stacks of entries pushed by the 'keep alive'
1437 // oop closure (an instance of G1CMKeepAliveAndDrainClosure above).
1438 //
1439 // G1CMTask::do_marking_step() is called in a loop, which we'll exit
1440 // if there's nothing more to do (i.e. we've completely drained the
1441 // entries that were pushed as a a result of applying the 'keep alive'
1442 // closure to the entries on the discovered ref lists) or we overflow
1443 // the global marking stack.
1444 //
1445 // Note: G1CMTask::do_marking_step() can set the G1CMTask::has_aborted()
1446 // flag while there may still be some work to do. (See the comment at
1447 // the beginning of G1CMTask::do_marking_step() for those conditions -
1448 // one of which is reaching the specified time target.) It is only
1449 // when G1CMTask::do_marking_step() returns without setting the
1450 // has_aborted() flag that the marking step has completed.
1451
1452 _task->do_marking_step(1000000000.0 /* something very large */,
1453 true /* do_termination */,
1454 _is_serial);
1455 } while (_task->has_aborted() && !_cm->has_overflown());
1456 }
1457 };
1458
1459 // Implementation of AbstractRefProcTaskExecutor for parallel
1460 // reference processing at the end of G1 concurrent marking
1461
1462 class G1CMRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
1463 private:
1464 G1CollectedHeap* _g1h;
1465 G1ConcurrentMark* _cm;
1466 WorkGang* _workers;
1467 uint _active_workers;
1468
1469 public:
1470 G1CMRefProcTaskExecutor(G1CollectedHeap* g1h,
1471 G1ConcurrentMark* cm,
1472 WorkGang* workers,
1473 uint n_workers) :
1474 _g1h(g1h), _cm(cm),
1475 _workers(workers), _active_workers(n_workers) { }
1476
1477 // Executes the given task using concurrent marking worker threads.
1478 virtual void execute(ProcessTask& task);
1479 virtual void execute(EnqueueTask& task);
1480 };
1481
1482 class G1CMRefProcTaskProxy: public AbstractGangTask {
1483 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
1484 ProcessTask& _proc_task;
1485 G1CollectedHeap* _g1h;
1486 G1ConcurrentMark* _cm;
1487
1488 public:
1489 G1CMRefProcTaskProxy(ProcessTask& proc_task,
1490 G1CollectedHeap* g1h,
1491 G1ConcurrentMark* cm) :
1492 AbstractGangTask("Process reference objects in parallel"),
1493 _proc_task(proc_task), _g1h(g1h), _cm(cm) {
1494 ReferenceProcessor* rp = _g1h->ref_processor_cm();
1495 assert(rp->processing_is_mt(), "shouldn't be here otherwise");
1496 }
1497
1498 virtual void work(uint worker_id) {
1499 ResourceMark rm;
1500 HandleMark hm;
1501 G1CMTask* task = _cm->task(worker_id);
1502 G1CMIsAliveClosure g1_is_alive(_g1h);
1503 G1CMKeepAliveAndDrainClosure g1_par_keep_alive(_cm, task, false /* is_serial */);
1504 G1CMDrainMarkingStackClosure g1_par_drain(_cm, task, false /* is_serial */);
1505
1506 _proc_task.work(worker_id, g1_is_alive, g1_par_keep_alive, g1_par_drain);
1507 }
1508 };
1509
1510 void G1CMRefProcTaskExecutor::execute(ProcessTask& proc_task) {
1511 assert(_workers != NULL, "Need parallel worker threads.");
1512 assert(_g1h->ref_processor_cm()->processing_is_mt(), "processing is not MT");
1513
1514 G1CMRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _cm);
1515
1516 // We need to reset the concurrency level before each
1517 // proxy task execution, so that the termination protocol
1518 // and overflow handling in G1CMTask::do_marking_step() knows
1519 // how many workers to wait for.
1520 _cm->set_concurrency(_active_workers);
1521 _workers->run_task(&proc_task_proxy);
1522 }
1523
1524 class G1CMRefEnqueueTaskProxy: public AbstractGangTask {
1525 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
1526 EnqueueTask& _enq_task;
1527
1528 public:
1529 G1CMRefEnqueueTaskProxy(EnqueueTask& enq_task) :
1530 AbstractGangTask("Enqueue reference objects in parallel"),
1531 _enq_task(enq_task) { }
1532
1533 virtual void work(uint worker_id) {
1534 _enq_task.work(worker_id);
1535 }
1536 };
1537
1538 void G1CMRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
1539 assert(_workers != NULL, "Need parallel worker threads.");
1540 assert(_g1h->ref_processor_cm()->processing_is_mt(), "processing is not MT");
1541
1542 G1CMRefEnqueueTaskProxy enq_task_proxy(enq_task);
1543
1544 // Not strictly necessary but...
1545 //
1546 // We need to reset the concurrency level before each
1547 // proxy task execution, so that the termination protocol
1548 // and overflow handling in G1CMTask::do_marking_step() knows
1549 // how many workers to wait for.
1550 _cm->set_concurrency(_active_workers);
1551 _workers->run_task(&enq_task_proxy);
1552 }
1553
1554 void G1ConcurrentMark::weak_refs_work(bool clear_all_soft_refs) {
1555 if (has_overflown()) {
1556 // Skip processing the discovered references if we have
1557 // overflown the global marking stack. Reference objects
1558 // only get discovered once so it is OK to not
1559 // de-populate the discovered reference lists. We could have,
1560 // but the only benefit would be that, when marking restarts,
1561 // less reference objects are discovered.
1562 return;
1563 }
1564
1565 ResourceMark rm;
1566 HandleMark hm;
1567
1568 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1569
1570 // Is alive closure.
1571 G1CMIsAliveClosure g1_is_alive(g1h);
1572
1573 // Inner scope to exclude the cleaning of the string and symbol
1574 // tables from the displayed time.
1575 {
1576 GCTraceTime(Debug, gc, phases) trace("Reference Processing", _gc_timer_cm);
1577
1578 ReferenceProcessor* rp = g1h->ref_processor_cm();
1579
1580 // See the comment in G1CollectedHeap::ref_processing_init()
1581 // about how reference processing currently works in G1.
1582
1583 // Set the soft reference policy
1584 rp->setup_policy(clear_all_soft_refs);
1585 assert(_global_mark_stack.is_empty(), "mark stack should be empty");
1586
1587 // Instances of the 'Keep Alive' and 'Complete GC' closures used
1588 // in serial reference processing. Note these closures are also
1589 // used for serially processing (by the the current thread) the
1590 // JNI references during parallel reference processing.
1591 //
1592 // These closures do not need to synchronize with the worker
1593 // threads involved in parallel reference processing as these
1594 // instances are executed serially by the current thread (e.g.
1595 // reference processing is not multi-threaded and is thus
1596 // performed by the current thread instead of a gang worker).
1597 //
1598 // The gang tasks involved in parallel reference processing create
1599 // their own instances of these closures, which do their own
1600 // synchronization among themselves.
1601 G1CMKeepAliveAndDrainClosure g1_keep_alive(this, task(0), true /* is_serial */);
1602 G1CMDrainMarkingStackClosure g1_drain_mark_stack(this, task(0), true /* is_serial */);
1603
1604 // We need at least one active thread. If reference processing
1605 // is not multi-threaded we use the current (VMThread) thread,
1606 // otherwise we use the work gang from the G1CollectedHeap and
1607 // we utilize all the worker threads we can.
1608 bool processing_is_mt = rp->processing_is_mt();
1609 uint active_workers = (processing_is_mt ? g1h->workers()->active_workers() : 1U);
1610 active_workers = MAX2(MIN2(active_workers, _max_num_tasks), 1U);
1611
1612 // Parallel processing task executor.
1613 G1CMRefProcTaskExecutor par_task_executor(g1h, this,
1614 g1h->workers(), active_workers);
1615 AbstractRefProcTaskExecutor* executor = (processing_is_mt ? &par_task_executor : NULL);
1616
1617 // Set the concurrency level. The phase was already set prior to
1618 // executing the remark task.
1619 set_concurrency(active_workers);
1620
1621 // Set the degree of MT processing here. If the discovery was done MT,
1622 // the number of threads involved during discovery could differ from
1623 // the number of active workers. This is OK as long as the discovered
1624 // Reference lists are balanced (see balance_all_queues() and balance_queues()).
1625 rp->set_active_mt_degree(active_workers);
1626
1627 ReferenceProcessorPhaseTimes pt(_gc_timer_cm, rp->num_q());
1628
1629 // Process the weak references.
1630 const ReferenceProcessorStats& stats =
1631 rp->process_discovered_references(&g1_is_alive,
1632 &g1_keep_alive,
1633 &g1_drain_mark_stack,
1634 executor,
1635 &pt);
1636 _gc_tracer_cm->report_gc_reference_stats(stats);
1637 pt.print_all_references();
1638
1639 // The do_oop work routines of the keep_alive and drain_marking_stack
1640 // oop closures will set the has_overflown flag if we overflow the
1641 // global marking stack.
1642
1643 assert(has_overflown() || _global_mark_stack.is_empty(),
1644 "Mark stack should be empty (unless it has overflown)");
1645
1646 assert(rp->num_q() == active_workers, "why not");
1647
1648 rp->enqueue_discovered_references(executor, &pt);
1649
1650 rp->verify_no_references_recorded();
1651
1652 pt.print_enqueue_phase();
1653
1654 assert(!rp->discovery_enabled(), "Post condition");
1655 }
1656
1657 assert(has_overflown() || _global_mark_stack.is_empty(),
1658 "Mark stack should be empty (unless it has overflown)");
1659
1660 {
1661 GCTraceTime(Debug, gc, phases) debug("Weak Processing", _gc_timer_cm);
1662 WeakProcessor::weak_oops_do(&g1_is_alive, &do_nothing_cl);
1663 }
1664
1665 if (has_overflown()) {
1666 // We can not trust g1_is_alive if the marking stack overflowed
1667 return;
1668 }
1669
1670 assert(_global_mark_stack.is_empty(), "Marking should have completed");
1671
1672 // Unload Klasses, String, Symbols, Code Cache, etc.
1673 if (ClassUnloadingWithConcurrentMark) {
1674 GCTraceTime(Debug, gc, phases) debug("Class Unloading", _gc_timer_cm);
1675 bool purged_classes = SystemDictionary::do_unloading(&g1_is_alive, _gc_timer_cm, false /* Defer cleaning */);
1676 g1h->complete_cleaning(&g1_is_alive, purged_classes);
1677 } else {
1678 GCTraceTime(Debug, gc, phases) debug("Cleanup", _gc_timer_cm);
1679 // No need to clean string table and symbol table as they are treated as strong roots when
1680 // class unloading is disabled.
1681 g1h->partial_cleaning(&g1_is_alive, false, false, G1StringDedup::is_enabled());
1682
1683 }
1684 }
1685
1686 void G1ConcurrentMark::swap_mark_bitmaps() {
1687 G1CMBitMap* temp = _prev_mark_bitmap;
1688 _prev_mark_bitmap = _next_mark_bitmap;
1689 _next_mark_bitmap = temp;
1690 }
1691
1692 // Closure for marking entries in SATB buffers.
1693 class G1CMSATBBufferClosure : public SATBBufferClosure {
1694 private:
1695 G1CMTask* _task;
1696 G1CollectedHeap* _g1h;
1697
1698 // This is very similar to G1CMTask::deal_with_reference, but with
1699 // more relaxed requirements for the argument, so this must be more
1700 // circumspect about treating the argument as an object.
1701 void do_entry(void* entry) const {
1702 _task->increment_refs_reached();
1703 oop const obj = static_cast<oop>(entry);
1704 _task->make_reference_grey(obj);
1705 }
1706
1707 public:
1708 G1CMSATBBufferClosure(G1CMTask* task, G1CollectedHeap* g1h)
1709 : _task(task), _g1h(g1h) { }
1710
1711 virtual void do_buffer(void** buffer, size_t size) {
1712 for (size_t i = 0; i < size; ++i) {
1713 do_entry(buffer[i]);
1714 }
1715 }
1716 };
1717
1718 class G1RemarkThreadsClosure : public ThreadClosure {
1719 G1CMSATBBufferClosure _cm_satb_cl;
1720 G1CMOopClosure _cm_cl;
1721 MarkingCodeBlobClosure _code_cl;
1722 int _thread_parity;
1723
1724 public:
1725 G1RemarkThreadsClosure(G1CollectedHeap* g1h, G1CMTask* task) :
1726 _cm_satb_cl(task, g1h),
1727 _cm_cl(g1h, g1h->concurrent_mark(), task),
1728 _code_cl(&_cm_cl, !CodeBlobToOopClosure::FixRelocations),
1729 _thread_parity(Threads::thread_claim_parity()) {}
1730
1731 void do_thread(Thread* thread) {
1732 if (thread->is_Java_thread()) {
1733 if (thread->claim_oops_do(true, _thread_parity)) {
1734 JavaThread* jt = (JavaThread*)thread;
1735
1736 // In theory it should not be neccessary to explicitly walk the nmethods to find roots for concurrent marking
1737 // however the liveness of oops reachable from nmethods have very complex lifecycles:
1738 // * Alive if on the stack of an executing method
1739 // * Weakly reachable otherwise
1740 // Some objects reachable from nmethods, such as the class loader (or klass_holder) of the receiver should be
1741 // live by the SATB invariant but other oops recorded in nmethods may behave differently.
1742 jt->nmethods_do(&_code_cl);
1743
1744 jt->satb_mark_queue().apply_closure_and_empty(&_cm_satb_cl);
1745 }
1746 } else if (thread->is_VM_thread()) {
1747 if (thread->claim_oops_do(true, _thread_parity)) {
1748 JavaThread::satb_mark_queue_set().shared_satb_queue()->apply_closure_and_empty(&_cm_satb_cl);
1749 }
1750 }
1751 }
1752 };
1753
1754 class G1CMRemarkTask: public AbstractGangTask {
1755 private:
1756 G1ConcurrentMark* _cm;
1757 public:
1758 void work(uint worker_id) {
1759 G1CMTask* task = _cm->task(worker_id);
1760 task->record_start_time();
1761 {
1762 ResourceMark rm;
1763 HandleMark hm;
1764
1765 G1RemarkThreadsClosure threads_f(G1CollectedHeap::heap(), task);
1766 Threads::threads_do(&threads_f);
1767 }
1768
1769 do {
1770 task->do_marking_step(1000000000.0 /* something very large */,
1771 true /* do_termination */,
1772 false /* is_serial */);
1773 } while (task->has_aborted() && !_cm->has_overflown());
1774 // If we overflow, then we do not want to restart. We instead
1775 // want to abort remark and do concurrent marking again.
1776 task->record_end_time();
1777 }
1778
1779 G1CMRemarkTask(G1ConcurrentMark* cm, uint active_workers) :
1780 AbstractGangTask("Par Remark"), _cm(cm) {
1781 _cm->terminator()->reset_for_reuse(active_workers);
1782 }
1783 };
1784
1785 void G1ConcurrentMark::checkpoint_roots_final_work() {
1786 ResourceMark rm;
1787 HandleMark hm;
1788 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1789
1790 GCTraceTime(Debug, gc, phases) trace("Finalize Marking", _gc_timer_cm);
1791
1792 g1h->ensure_parsability(false);
1793
1794 // this is remark, so we'll use up all active threads
1795 uint active_workers = g1h->workers()->active_workers();
1796 set_concurrency_and_phase(active_workers, false /* concurrent */);
1797 // Leave _parallel_marking_threads at it's
1798 // value originally calculated in the G1ConcurrentMark
1799 // constructor and pass values of the active workers
1800 // through the gang in the task.
1801
1802 {
1803 StrongRootsScope srs(active_workers);
1804
1805 G1CMRemarkTask remarkTask(this, active_workers);
1806 // We will start all available threads, even if we decide that the
1807 // active_workers will be fewer. The extra ones will just bail out
1808 // immediately.
1809 g1h->workers()->run_task(&remarkTask);
1810 }
1811
1812 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
1813 guarantee(has_overflown() ||
1814 satb_mq_set.completed_buffers_num() == 0,
1815 "Invariant: has_overflown = %s, num buffers = " SIZE_FORMAT,
1816 BOOL_TO_STR(has_overflown()),
1817 satb_mq_set.completed_buffers_num());
1818
1819 print_stats();
1820 }
1821
1822 void G1ConcurrentMark::clear_range_in_prev_bitmap(MemRegion mr) {
1823 _prev_mark_bitmap->clear_range(mr);
1824 }
1825
1826 HeapRegion*
1827 G1ConcurrentMark::claim_region(uint worker_id) {
1828 // "checkpoint" the finger
1829 HeapWord* finger = _finger;
1830
1831 // _heap_end will not change underneath our feet; it only changes at
1832 // yield points.
1833 while (finger < _heap_end) {
1834 assert(_g1h->is_in_g1_reserved(finger), "invariant");
1835
1836 HeapRegion* curr_region = _g1h->heap_region_containing(finger);
1837 // Make sure that the reads below do not float before loading curr_region.
1838 OrderAccess::loadload();
1839 // Above heap_region_containing may return NULL as we always scan claim
1840 // until the end of the heap. In this case, just jump to the next region.
1841 HeapWord* end = curr_region != NULL ? curr_region->end() : finger + HeapRegion::GrainWords;
1842
1843 // Is the gap between reading the finger and doing the CAS too long?
1844 HeapWord* res = Atomic::cmpxchg(end, &_finger, finger);
1845 if (res == finger && curr_region != NULL) {
1846 // we succeeded
1847 HeapWord* bottom = curr_region->bottom();
1848 HeapWord* limit = curr_region->next_top_at_mark_start();
1849
1850 // notice that _finger == end cannot be guaranteed here since,
1851 // someone else might have moved the finger even further
1852 assert(_finger >= end, "the finger should have moved forward");
1853
1854 if (limit > bottom) {
1855 return curr_region;
1856 } else {
1857 assert(limit == bottom,
1858 "the region limit should be at bottom");
1859 // we return NULL and the caller should try calling
1860 // claim_region() again.
1861 return NULL;
1862 }
1863 } else {
1864 assert(_finger > finger, "the finger should have moved forward");
1865 // read it again
1866 finger = _finger;
1867 }
1868 }
1869
1870 return NULL;
1871 }
1872
1873 #ifndef PRODUCT
1874 class VerifyNoCSetOops VALUE_OBJ_CLASS_SPEC {
1875 private:
1876 G1CollectedHeap* _g1h;
1877 const char* _phase;
1878 int _info;
1879
1880 public:
1881 VerifyNoCSetOops(const char* phase, int info = -1) :
1882 _g1h(G1CollectedHeap::heap()),
1883 _phase(phase),
1884 _info(info)
1885 { }
1886
1887 void operator()(G1TaskQueueEntry task_entry) const {
1888 if (task_entry.is_array_slice()) {
1889 guarantee(_g1h->is_in_reserved(task_entry.slice()), "Slice " PTR_FORMAT " must be in heap.", p2i(task_entry.slice()));
1890 return;
1891 }
1892 guarantee(oopDesc::is_oop(task_entry.obj()),
1893 "Non-oop " PTR_FORMAT ", phase: %s, info: %d",
1894 p2i(task_entry.obj()), _phase, _info);
1895 guarantee(!_g1h->is_in_cset(task_entry.obj()),
1896 "obj: " PTR_FORMAT " in CSet, phase: %s, info: %d",
1897 p2i(task_entry.obj()), _phase, _info);
1898 }
1899 };
1900
1901 void G1ConcurrentMark::verify_no_cset_oops() {
1902 assert(SafepointSynchronize::is_at_safepoint(), "should be at a safepoint");
1903 if (!G1CollectedHeap::heap()->collector_state()->mark_in_progress()) {
1904 return;
1905 }
1906
1907 // Verify entries on the global mark stack
1908 _global_mark_stack.iterate(VerifyNoCSetOops("Stack"));
1909
1910 // Verify entries on the task queues
1911 for (uint i = 0; i < _max_num_tasks; ++i) {
1912 G1CMTaskQueue* queue = _task_queues->queue(i);
1913 queue->iterate(VerifyNoCSetOops("Queue", i));
1914 }
1915
1916 // Verify the global finger
1917 HeapWord* global_finger = finger();
1918 if (global_finger != NULL && global_finger < _heap_end) {
1919 // Since we always iterate over all regions, we might get a NULL HeapRegion
1920 // here.
1921 HeapRegion* global_hr = _g1h->heap_region_containing(global_finger);
1922 guarantee(global_hr == NULL || global_finger == global_hr->bottom(),
1923 "global finger: " PTR_FORMAT " region: " HR_FORMAT,
1924 p2i(global_finger), HR_FORMAT_PARAMS(global_hr));
1925 }
1926
1927 // Verify the task fingers
1928 assert(_num_concurrent_workers <= _max_num_tasks, "sanity");
1929 for (uint i = 0; i < _num_concurrent_workers; ++i) {
1930 G1CMTask* task = _tasks[i];
1931 HeapWord* task_finger = task->finger();
1932 if (task_finger != NULL && task_finger < _heap_end) {
1933 // See above note on the global finger verification.
1934 HeapRegion* task_hr = _g1h->heap_region_containing(task_finger);
1935 guarantee(task_hr == NULL || task_finger == task_hr->bottom() ||
1936 !task_hr->in_collection_set(),
1937 "task finger: " PTR_FORMAT " region: " HR_FORMAT,
1938 p2i(task_finger), HR_FORMAT_PARAMS(task_hr));
1939 }
1940 }
1941 }
1942 #endif // PRODUCT
1943 void G1ConcurrentMark::create_live_data() {
1944 _g1h->g1_rem_set()->create_card_live_data(_concurrent_workers, _next_mark_bitmap);
1945 }
1946
1947 void G1ConcurrentMark::finalize_live_data() {
1948 _g1h->g1_rem_set()->finalize_card_live_data(_g1h->workers(), _next_mark_bitmap);
1949 }
1950
1951 void G1ConcurrentMark::verify_live_data() {
1952 _g1h->g1_rem_set()->verify_card_live_data(_g1h->workers(), _next_mark_bitmap);
1953 }
1954
1955 void G1ConcurrentMark::clear_live_data(WorkGang* workers) {
1956 _g1h->g1_rem_set()->clear_card_live_data(workers);
1957 }
1958
1959 #ifdef ASSERT
1960 void G1ConcurrentMark::verify_live_data_clear() {
1961 _g1h->g1_rem_set()->verify_card_live_data_is_clear();
1962 }
1963 #endif
1964
1965 void G1ConcurrentMark::print_stats() {
1966 if (!log_is_enabled(Debug, gc, stats)) {
1967 return;
1968 }
1969 log_debug(gc, stats)("---------------------------------------------------------------------");
1970 for (size_t i = 0; i < _num_active_tasks; ++i) {
1971 _tasks[i]->print_stats();
1972 log_debug(gc, stats)("---------------------------------------------------------------------");
1973 }
1974 }
1975
1976 void G1ConcurrentMark::abort() {
1977 if (!cm_thread()->during_cycle() || _has_aborted) {
1978 // We haven't started a concurrent cycle or we have already aborted it. No need to do anything.
1979 return;
1980 }
1981
1982 // Clear all marks in the next bitmap for the next marking cycle. This will allow us to skip the next
1983 // concurrent bitmap clearing.
1984 {
1985 GCTraceTime(Debug, gc)("Clear Next Bitmap");
1986 clear_bitmap(_next_mark_bitmap, _g1h->workers(), false);
1987 }
1988 // Note we cannot clear the previous marking bitmap here
1989 // since VerifyDuringGC verifies the objects marked during
1990 // a full GC against the previous bitmap.
1991
1992 {
1993 GCTraceTime(Debug, gc)("Clear Live Data");
1994 clear_live_data(_g1h->workers());
1995 }
1996 DEBUG_ONLY({
1997 GCTraceTime(Debug, gc)("Verify Live Data Clear");
1998 verify_live_data_clear();
1999 })
2000 // Empty mark stack
2001 reset_marking_state();
2002 for (uint i = 0; i < _max_num_tasks; ++i) {
2003 _tasks[i]->clear_region_fields();
2004 }
2005 _first_overflow_barrier_sync.abort();
2006 _second_overflow_barrier_sync.abort();
2007 _has_aborted = true;
2008
2009 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
2010 satb_mq_set.abandon_partial_marking();
2011 // This can be called either during or outside marking, we'll read
2012 // the expected_active value from the SATB queue set.
2013 satb_mq_set.set_active_all_threads(
2014 false, /* new active value */
2015 satb_mq_set.is_active() /* expected_active */);
2016 }
2017
2018 static void print_ms_time_info(const char* prefix, const char* name,
2019 NumberSeq& ns) {
2020 log_trace(gc, marking)("%s%5d %12s: total time = %8.2f s (avg = %8.2f ms).",
2021 prefix, ns.num(), name, ns.sum()/1000.0, ns.avg());
2022 if (ns.num() > 0) {
2023 log_trace(gc, marking)("%s [std. dev = %8.2f ms, max = %8.2f ms]",
2024 prefix, ns.sd(), ns.maximum());
2025 }
2026 }
2027
2028 void G1ConcurrentMark::print_summary_info() {
2029 Log(gc, marking) log;
2030 if (!log.is_trace()) {
2031 return;
2032 }
2033
2034 log.trace(" Concurrent marking:");
2035 print_ms_time_info(" ", "init marks", _init_times);
2036 print_ms_time_info(" ", "remarks", _remark_times);
2037 {
2038 print_ms_time_info(" ", "final marks", _remark_mark_times);
2039 print_ms_time_info(" ", "weak refs", _remark_weak_ref_times);
2040
2041 }
2042 print_ms_time_info(" ", "cleanups", _cleanup_times);
2043 log.trace(" Finalize live data total time = %8.2f s (avg = %8.2f ms).",
2044 _total_counting_time, (_cleanup_times.num() > 0 ? _total_counting_time * 1000.0 / (double)_cleanup_times.num() : 0.0));
2045 if (G1ScrubRemSets) {
2046 log.trace(" RS scrub total time = %8.2f s (avg = %8.2f ms).",
2047 _total_rs_scrub_time, (_cleanup_times.num() > 0 ? _total_rs_scrub_time * 1000.0 / (double)_cleanup_times.num() : 0.0));
2048 }
2049 log.trace(" Total stop_world time = %8.2f s.",
2050 (_init_times.sum() + _remark_times.sum() + _cleanup_times.sum())/1000.0);
2051 log.trace(" Total concurrent time = %8.2f s (%8.2f s marking).",
2052 cm_thread()->vtime_accum(), cm_thread()->vtime_mark_accum());
2053 }
2054
2055 void G1ConcurrentMark::print_worker_threads_on(outputStream* st) const {
2056 _concurrent_workers->print_worker_threads_on(st);
2057 }
2058
2059 void G1ConcurrentMark::threads_do(ThreadClosure* tc) const {
2060 _concurrent_workers->threads_do(tc);
2061 }
2062
2063 void G1ConcurrentMark::print_on_error(outputStream* st) const {
2064 st->print_cr("Marking Bits (Prev, Next): (CMBitMap*) " PTR_FORMAT ", (CMBitMap*) " PTR_FORMAT,
2065 p2i(_prev_mark_bitmap), p2i(_next_mark_bitmap));
2066 _prev_mark_bitmap->print_on_error(st, " Prev Bits: ");
2067 _next_mark_bitmap->print_on_error(st, " Next Bits: ");
2068 }
2069
2070 static ReferenceProcessor* get_cm_oop_closure_ref_processor(G1CollectedHeap* g1h) {
2071 ReferenceProcessor* result = g1h->ref_processor_cm();
2072 assert(result != NULL, "CM reference processor should not be NULL");
2073 return result;
2074 }
2075
2076 G1CMOopClosure::G1CMOopClosure(G1CollectedHeap* g1h,
2077 G1ConcurrentMark* cm,
2078 G1CMTask* task)
2079 : MetadataAwareOopClosure(get_cm_oop_closure_ref_processor(g1h)),
2080 _g1h(g1h), _cm(cm), _task(task)
2081 { }
2082
2083 void G1CMTask::setup_for_region(HeapRegion* hr) {
2084 assert(hr != NULL,
2085 "claim_region() should have filtered out NULL regions");
2086 _curr_region = hr;
2087 _finger = hr->bottom();
2088 update_region_limit();
2089 }
2090
2091 void G1CMTask::update_region_limit() {
2092 HeapRegion* hr = _curr_region;
2093 HeapWord* bottom = hr->bottom();
2094 HeapWord* limit = hr->next_top_at_mark_start();
2095
2096 if (limit == bottom) {
2097 // The region was collected underneath our feet.
2098 // We set the finger to bottom to ensure that the bitmap
2099 // iteration that will follow this will not do anything.
2100 // (this is not a condition that holds when we set the region up,
2101 // as the region is not supposed to be empty in the first place)
2102 _finger = bottom;
2103 } else if (limit >= _region_limit) {
2104 assert(limit >= _finger, "peace of mind");
2105 } else {
2106 assert(limit < _region_limit, "only way to get here");
2107 // This can happen under some pretty unusual circumstances. An
2108 // evacuation pause empties the region underneath our feet (NTAMS
2109 // at bottom). We then do some allocation in the region (NTAMS
2110 // stays at bottom), followed by the region being used as a GC
2111 // alloc region (NTAMS will move to top() and the objects
2112 // originally below it will be grayed). All objects now marked in
2113 // the region are explicitly grayed, if below the global finger,
2114 // and we do not need in fact to scan anything else. So, we simply
2115 // set _finger to be limit to ensure that the bitmap iteration
2116 // doesn't do anything.
2117 _finger = limit;
2118 }
2119
2120 _region_limit = limit;
2121 }
2122
2123 void G1CMTask::giveup_current_region() {
2124 assert(_curr_region != NULL, "invariant");
2125 clear_region_fields();
2126 }
2127
2128 void G1CMTask::clear_region_fields() {
2129 // Values for these three fields that indicate that we're not
2130 // holding on to a region.
2131 _curr_region = NULL;
2132 _finger = NULL;
2133 _region_limit = NULL;
2134 }
2135
2136 void G1CMTask::set_cm_oop_closure(G1CMOopClosure* cm_oop_closure) {
2137 if (cm_oop_closure == NULL) {
2138 assert(_cm_oop_closure != NULL, "invariant");
2139 } else {
2140 assert(_cm_oop_closure == NULL, "invariant");
2141 }
2142 _cm_oop_closure = cm_oop_closure;
2143 }
2144
2145 void G1CMTask::reset(G1CMBitMap* next_mark_bitmap) {
2146 guarantee(next_mark_bitmap != NULL, "invariant");
2147 _next_mark_bitmap = next_mark_bitmap;
2148 clear_region_fields();
2149
2150 _calls = 0;
2151 _elapsed_time_ms = 0.0;
2152 _termination_time_ms = 0.0;
2153 _termination_start_time_ms = 0.0;
2154 }
2155
2156 bool G1CMTask::should_exit_termination() {
2157 regular_clock_call();
2158 // This is called when we are in the termination protocol. We should
2159 // quit if, for some reason, this task wants to abort or the global
2160 // stack is not empty (this means that we can get work from it).
2161 return !_cm->mark_stack_empty() || has_aborted();
2162 }
2163
2164 void G1CMTask::reached_limit() {
2165 assert(_words_scanned >= _words_scanned_limit ||
2166 _refs_reached >= _refs_reached_limit ,
2167 "shouldn't have been called otherwise");
2168 regular_clock_call();
2169 }
2170
2171 void G1CMTask::regular_clock_call() {
2172 if (has_aborted()) return;
2173
2174 // First, we need to recalculate the words scanned and refs reached
2175 // limits for the next clock call.
2176 recalculate_limits();
2177
2178 // During the regular clock call we do the following
2179
2180 // (1) If an overflow has been flagged, then we abort.
2181 if (_cm->has_overflown()) {
2182 set_has_aborted();
2183 return;
2184 }
2185
2186 // If we are not concurrent (i.e. we're doing remark) we don't need
2187 // to check anything else. The other steps are only needed during
2188 // the concurrent marking phase.
2189 if (!_concurrent) {
2190 return;
2191 }
2192
2193 // (2) If marking has been aborted for Full GC, then we also abort.
2194 if (_cm->has_aborted()) {
2195 set_has_aborted();
2196 return;
2197 }
2198
2199 double curr_time_ms = os::elapsedVTime() * 1000.0;
2200
2201 // (4) We check whether we should yield. If we have to, then we abort.
2202 if (SuspendibleThreadSet::should_yield()) {
2203 // We should yield. To do this we abort the task. The caller is
2204 // responsible for yielding.
2205 set_has_aborted();
2206 return;
2207 }
2208
2209 // (5) We check whether we've reached our time quota. If we have,
2210 // then we abort.
2211 double elapsed_time_ms = curr_time_ms - _start_time_ms;
2212 if (elapsed_time_ms > _time_target_ms) {
2213 set_has_aborted();
2214 _has_timed_out = true;
2215 return;
2216 }
2217
2218 // (6) Finally, we check whether there are enough completed STAB
2219 // buffers available for processing. If there are, we abort.
2220 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
2221 if (!_draining_satb_buffers && satb_mq_set.process_completed_buffers()) {
2222 // we do need to process SATB buffers, we'll abort and restart
2223 // the marking task to do so
2224 set_has_aborted();
2225 return;
2226 }
2227 }
2228
2229 void G1CMTask::recalculate_limits() {
2230 _real_words_scanned_limit = _words_scanned + words_scanned_period;
2231 _words_scanned_limit = _real_words_scanned_limit;
2232
2233 _real_refs_reached_limit = _refs_reached + refs_reached_period;
2234 _refs_reached_limit = _real_refs_reached_limit;
2235 }
2236
2237 void G1CMTask::decrease_limits() {
2238 // This is called when we believe that we're going to do an infrequent
2239 // operation which will increase the per byte scanned cost (i.e. move
2240 // entries to/from the global stack). It basically tries to decrease the
2241 // scanning limit so that the clock is called earlier.
2242
2243 _words_scanned_limit = _real_words_scanned_limit - 3 * words_scanned_period / 4;
2244 _refs_reached_limit = _real_refs_reached_limit - 3 * refs_reached_period / 4;
2245 }
2246
2247 void G1CMTask::move_entries_to_global_stack() {
2248 // Local array where we'll store the entries that will be popped
2249 // from the local queue.
2250 G1TaskQueueEntry buffer[G1CMMarkStack::EntriesPerChunk];
2251
2252 size_t n = 0;
2253 G1TaskQueueEntry task_entry;
2254 while (n < G1CMMarkStack::EntriesPerChunk && _task_queue->pop_local(task_entry)) {
2255 buffer[n] = task_entry;
2256 ++n;
2257 }
2258 if (n < G1CMMarkStack::EntriesPerChunk) {
2259 buffer[n] = G1TaskQueueEntry();
2260 }
2261
2262 if (n > 0) {
2263 if (!_cm->mark_stack_push(buffer)) {
2264 set_has_aborted();
2265 }
2266 }
2267
2268 // This operation was quite expensive, so decrease the limits.
2269 decrease_limits();
2270 }
2271
2272 bool G1CMTask::get_entries_from_global_stack() {
2273 // Local array where we'll store the entries that will be popped
2274 // from the global stack.
2275 G1TaskQueueEntry buffer[G1CMMarkStack::EntriesPerChunk];
2276
2277 if (!_cm->mark_stack_pop(buffer)) {
2278 return false;
2279 }
2280
2281 // We did actually pop at least one entry.
2282 for (size_t i = 0; i < G1CMMarkStack::EntriesPerChunk; ++i) {
2283 G1TaskQueueEntry task_entry = buffer[i];
2284 if (task_entry.is_null()) {
2285 break;
2286 }
2287 assert(task_entry.is_array_slice() || oopDesc::is_oop(task_entry.obj()), "Element " PTR_FORMAT " must be an array slice or oop", p2i(task_entry.obj()));
2288 bool success = _task_queue->push(task_entry);
2289 // We only call this when the local queue is empty or under a
2290 // given target limit. So, we do not expect this push to fail.
2291 assert(success, "invariant");
2292 }
2293
2294 // This operation was quite expensive, so decrease the limits
2295 decrease_limits();
2296 return true;
2297 }
2298
2299 void G1CMTask::drain_local_queue(bool partially) {
2300 if (has_aborted()) {
2301 return;
2302 }
2303
2304 // Decide what the target size is, depending whether we're going to
2305 // drain it partially (so that other tasks can steal if they run out
2306 // of things to do) or totally (at the very end).
2307 size_t target_size;
2308 if (partially) {
2309 target_size = MIN2((size_t)_task_queue->max_elems()/3, GCDrainStackTargetSize);
2310 } else {
2311 target_size = 0;
2312 }
2313
2314 if (_task_queue->size() > target_size) {
2315 G1TaskQueueEntry entry;
2316 bool ret = _task_queue->pop_local(entry);
2317 while (ret) {
2318 scan_task_entry(entry);
2319 if (_task_queue->size() <= target_size || has_aborted()) {
2320 ret = false;
2321 } else {
2322 ret = _task_queue->pop_local(entry);
2323 }
2324 }
2325 }
2326 }
2327
2328 void G1CMTask::drain_global_stack(bool partially) {
2329 if (has_aborted()) return;
2330
2331 // We have a policy to drain the local queue before we attempt to
2332 // drain the global stack.
2333 assert(partially || _task_queue->size() == 0, "invariant");
2334
2335 // Decide what the target size is, depending whether we're going to
2336 // drain it partially (so that other tasks can steal if they run out
2337 // of things to do) or totally (at the very end).
2338 // Notice that when draining the global mark stack partially, due to the racyness
2339 // of the mark stack size update we might in fact drop below the target. But,
2340 // this is not a problem.
2341 // In case of total draining, we simply process until the global mark stack is
2342 // totally empty, disregarding the size counter.
2343 if (partially) {
2344 size_t const target_size = _cm->partial_mark_stack_size_target();
2345 while (!has_aborted() && _cm->mark_stack_size() > target_size) {
2346 if (get_entries_from_global_stack()) {
2347 drain_local_queue(partially);
2348 }
2349 }
2350 } else {
2351 while (!has_aborted() && get_entries_from_global_stack()) {
2352 drain_local_queue(partially);
2353 }
2354 }
2355 }
2356
2357 // SATB Queue has several assumptions on whether to call the par or
2358 // non-par versions of the methods. this is why some of the code is
2359 // replicated. We should really get rid of the single-threaded version
2360 // of the code to simplify things.
2361 void G1CMTask::drain_satb_buffers() {
2362 if (has_aborted()) return;
2363
2364 // We set this so that the regular clock knows that we're in the
2365 // middle of draining buffers and doesn't set the abort flag when it
2366 // notices that SATB buffers are available for draining. It'd be
2367 // very counter productive if it did that. :-)
2368 _draining_satb_buffers = true;
2369
2370 G1CMSATBBufferClosure satb_cl(this, _g1h);
2371 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
2372
2373 // This keeps claiming and applying the closure to completed buffers
2374 // until we run out of buffers or we need to abort.
2375 while (!has_aborted() &&
2376 satb_mq_set.apply_closure_to_completed_buffer(&satb_cl)) {
2377 regular_clock_call();
2378 }
2379
2380 _draining_satb_buffers = false;
2381
2382 assert(has_aborted() ||
2383 _concurrent ||
2384 satb_mq_set.completed_buffers_num() == 0, "invariant");
2385
2386 // again, this was a potentially expensive operation, decrease the
2387 // limits to get the regular clock call early
2388 decrease_limits();
2389 }
2390
2391 void G1CMTask::print_stats() {
2392 log_debug(gc, stats)("Marking Stats, task = %u, calls = %u",
2393 _worker_id, _calls);
2394 log_debug(gc, stats)(" Elapsed time = %1.2lfms, Termination time = %1.2lfms",
2395 _elapsed_time_ms, _termination_time_ms);
2396 log_debug(gc, stats)(" Step Times (cum): num = %d, avg = %1.2lfms, sd = %1.2lfms",
2397 _step_times_ms.num(), _step_times_ms.avg(),
2398 _step_times_ms.sd());
2399 log_debug(gc, stats)(" max = %1.2lfms, total = %1.2lfms",
2400 _step_times_ms.maximum(), _step_times_ms.sum());
2401 }
2402
2403 bool G1ConcurrentMark::try_stealing(uint worker_id, int* hash_seed, G1TaskQueueEntry& task_entry) {
2404 return _task_queues->steal(worker_id, hash_seed, task_entry);
2405 }
2406
2407 /*****************************************************************************
2408
2409 The do_marking_step(time_target_ms, ...) method is the building
2410 block of the parallel marking framework. It can be called in parallel
2411 with other invocations of do_marking_step() on different tasks
2412 (but only one per task, obviously) and concurrently with the
2413 mutator threads, or during remark, hence it eliminates the need
2414 for two versions of the code. When called during remark, it will
2415 pick up from where the task left off during the concurrent marking
2416 phase. Interestingly, tasks are also claimable during evacuation
2417 pauses too, since do_marking_step() ensures that it aborts before
2418 it needs to yield.
2419
2420 The data structures that it uses to do marking work are the
2421 following:
2422
2423 (1) Marking Bitmap. If there are gray objects that appear only
2424 on the bitmap (this happens either when dealing with an overflow
2425 or when the initial marking phase has simply marked the roots
2426 and didn't push them on the stack), then tasks claim heap
2427 regions whose bitmap they then scan to find gray objects. A
2428 global finger indicates where the end of the last claimed region
2429 is. A local finger indicates how far into the region a task has
2430 scanned. The two fingers are used to determine how to gray an
2431 object (i.e. whether simply marking it is OK, as it will be
2432 visited by a task in the future, or whether it needs to be also
2433 pushed on a stack).
2434
2435 (2) Local Queue. The local queue of the task which is accessed
2436 reasonably efficiently by the task. Other tasks can steal from
2437 it when they run out of work. Throughout the marking phase, a
2438 task attempts to keep its local queue short but not totally
2439 empty, so that entries are available for stealing by other
2440 tasks. Only when there is no more work, a task will totally
2441 drain its local queue.
2442
2443 (3) Global Mark Stack. This handles local queue overflow. During
2444 marking only sets of entries are moved between it and the local
2445 queues, as access to it requires a mutex and more fine-grain
2446 interaction with it which might cause contention. If it
2447 overflows, then the marking phase should restart and iterate
2448 over the bitmap to identify gray objects. Throughout the marking
2449 phase, tasks attempt to keep the global mark stack at a small
2450 length but not totally empty, so that entries are available for
2451 popping by other tasks. Only when there is no more work, tasks
2452 will totally drain the global mark stack.
2453
2454 (4) SATB Buffer Queue. This is where completed SATB buffers are
2455 made available. Buffers are regularly removed from this queue
2456 and scanned for roots, so that the queue doesn't get too
2457 long. During remark, all completed buffers are processed, as
2458 well as the filled in parts of any uncompleted buffers.
2459
2460 The do_marking_step() method tries to abort when the time target
2461 has been reached. There are a few other cases when the
2462 do_marking_step() method also aborts:
2463
2464 (1) When the marking phase has been aborted (after a Full GC).
2465
2466 (2) When a global overflow (on the global stack) has been
2467 triggered. Before the task aborts, it will actually sync up with
2468 the other tasks to ensure that all the marking data structures
2469 (local queues, stacks, fingers etc.) are re-initialized so that
2470 when do_marking_step() completes, the marking phase can
2471 immediately restart.
2472
2473 (3) When enough completed SATB buffers are available. The
2474 do_marking_step() method only tries to drain SATB buffers right
2475 at the beginning. So, if enough buffers are available, the
2476 marking step aborts and the SATB buffers are processed at
2477 the beginning of the next invocation.
2478
2479 (4) To yield. when we have to yield then we abort and yield
2480 right at the end of do_marking_step(). This saves us from a lot
2481 of hassle as, by yielding we might allow a Full GC. If this
2482 happens then objects will be compacted underneath our feet, the
2483 heap might shrink, etc. We save checking for this by just
2484 aborting and doing the yield right at the end.
2485
2486 From the above it follows that the do_marking_step() method should
2487 be called in a loop (or, otherwise, regularly) until it completes.
2488
2489 If a marking step completes without its has_aborted() flag being
2490 true, it means it has completed the current marking phase (and
2491 also all other marking tasks have done so and have all synced up).
2492
2493 A method called regular_clock_call() is invoked "regularly" (in
2494 sub ms intervals) throughout marking. It is this clock method that
2495 checks all the abort conditions which were mentioned above and
2496 decides when the task should abort. A work-based scheme is used to
2497 trigger this clock method: when the number of object words the
2498 marking phase has scanned or the number of references the marking
2499 phase has visited reach a given limit. Additional invocations to
2500 the method clock have been planted in a few other strategic places
2501 too. The initial reason for the clock method was to avoid calling
2502 vtime too regularly, as it is quite expensive. So, once it was in
2503 place, it was natural to piggy-back all the other conditions on it
2504 too and not constantly check them throughout the code.
2505
2506 If do_termination is true then do_marking_step will enter its
2507 termination protocol.
2508
2509 The value of is_serial must be true when do_marking_step is being
2510 called serially (i.e. by the VMThread) and do_marking_step should
2511 skip any synchronization in the termination and overflow code.
2512 Examples include the serial remark code and the serial reference
2513 processing closures.
2514
2515 The value of is_serial must be false when do_marking_step is
2516 being called by any of the worker threads in a work gang.
2517 Examples include the concurrent marking code (CMMarkingTask),
2518 the MT remark code, and the MT reference processing closures.
2519
2520 *****************************************************************************/
2521
2522 void G1CMTask::do_marking_step(double time_target_ms,
2523 bool do_termination,
2524 bool is_serial) {
2525 assert(time_target_ms >= 1.0, "minimum granularity is 1ms");
2526 assert(_concurrent == _cm->concurrent(), "they should be the same");
2527
2528 _start_time_ms = os::elapsedVTime() * 1000.0;
2529
2530 // If do_stealing is true then do_marking_step will attempt to
2531 // steal work from the other G1CMTasks. It only makes sense to
2532 // enable stealing when the termination protocol is enabled
2533 // and do_marking_step() is not being called serially.
2534 bool do_stealing = do_termination && !is_serial;
2535
2536 double diff_prediction_ms = _g1h->g1_policy()->predictor().get_new_prediction(&_marking_step_diffs_ms);
2537 _time_target_ms = time_target_ms - diff_prediction_ms;
2538
2539 // set up the variables that are used in the work-based scheme to
2540 // call the regular clock method
2541 _words_scanned = 0;
2542 _refs_reached = 0;
2543 recalculate_limits();
2544
2545 // clear all flags
2546 clear_has_aborted();
2547 _has_timed_out = false;
2548 _draining_satb_buffers = false;
2549
2550 ++_calls;
2551
2552 // Set up the bitmap and oop closures. Anything that uses them is
2553 // eventually called from this method, so it is OK to allocate these
2554 // statically.
2555 G1CMBitMapClosure bitmap_closure(this, _cm);
2556 G1CMOopClosure cm_oop_closure(_g1h, _cm, this);
2557 set_cm_oop_closure(&cm_oop_closure);
2558
2559 if (_cm->has_overflown()) {
2560 // This can happen if the mark stack overflows during a GC pause
2561 // and this task, after a yield point, restarts. We have to abort
2562 // as we need to get into the overflow protocol which happens
2563 // right at the end of this task.
2564 set_has_aborted();
2565 }
2566
2567 // First drain any available SATB buffers. After this, we will not
2568 // look at SATB buffers before the next invocation of this method.
2569 // If enough completed SATB buffers are queued up, the regular clock
2570 // will abort this task so that it restarts.
2571 drain_satb_buffers();
2572 // ...then partially drain the local queue and the global stack
2573 drain_local_queue(true);
2574 drain_global_stack(true);
2575
2576 do {
2577 if (!has_aborted() && _curr_region != NULL) {
2578 // This means that we're already holding on to a region.
2579 assert(_finger != NULL, "if region is not NULL, then the finger "
2580 "should not be NULL either");
2581
2582 // We might have restarted this task after an evacuation pause
2583 // which might have evacuated the region we're holding on to
2584 // underneath our feet. Let's read its limit again to make sure
2585 // that we do not iterate over a region of the heap that
2586 // contains garbage (update_region_limit() will also move
2587 // _finger to the start of the region if it is found empty).
2588 update_region_limit();
2589 // We will start from _finger not from the start of the region,
2590 // as we might be restarting this task after aborting half-way
2591 // through scanning this region. In this case, _finger points to
2592 // the address where we last found a marked object. If this is a
2593 // fresh region, _finger points to start().
2594 MemRegion mr = MemRegion(_finger, _region_limit);
2595
2596 assert(!_curr_region->is_humongous() || mr.start() == _curr_region->bottom(),
2597 "humongous regions should go around loop once only");
2598
2599 // Some special cases:
2600 // If the memory region is empty, we can just give up the region.
2601 // If the current region is humongous then we only need to check
2602 // the bitmap for the bit associated with the start of the object,
2603 // scan the object if it's live, and give up the region.
2604 // Otherwise, let's iterate over the bitmap of the part of the region
2605 // that is left.
2606 // If the iteration is successful, give up the region.
2607 if (mr.is_empty()) {
2608 giveup_current_region();
2609 regular_clock_call();
2610 } else if (_curr_region->is_humongous() && mr.start() == _curr_region->bottom()) {
2611 if (_next_mark_bitmap->is_marked(mr.start())) {
2612 // The object is marked - apply the closure
2613 bitmap_closure.do_addr(mr.start());
2614 }
2615 // Even if this task aborted while scanning the humongous object
2616 // we can (and should) give up the current region.
2617 giveup_current_region();
2618 regular_clock_call();
2619 } else if (_next_mark_bitmap->iterate(&bitmap_closure, mr)) {
2620 giveup_current_region();
2621 regular_clock_call();
2622 } else {
2623 assert(has_aborted(), "currently the only way to do so");
2624 // The only way to abort the bitmap iteration is to return
2625 // false from the do_bit() method. However, inside the
2626 // do_bit() method we move the _finger to point to the
2627 // object currently being looked at. So, if we bail out, we
2628 // have definitely set _finger to something non-null.
2629 assert(_finger != NULL, "invariant");
2630
2631 // Region iteration was actually aborted. So now _finger
2632 // points to the address of the object we last scanned. If we
2633 // leave it there, when we restart this task, we will rescan
2634 // the object. It is easy to avoid this. We move the finger by
2635 // enough to point to the next possible object header.
2636 assert(_finger < _region_limit, "invariant");
2637 HeapWord* const new_finger = _finger + ((oop)_finger)->size();
2638 // Check if bitmap iteration was aborted while scanning the last object
2639 if (new_finger >= _region_limit) {
2640 giveup_current_region();
2641 } else {
2642 move_finger_to(new_finger);
2643 }
2644 }
2645 }
2646 // At this point we have either completed iterating over the
2647 // region we were holding on to, or we have aborted.
2648
2649 // We then partially drain the local queue and the global stack.
2650 // (Do we really need this?)
2651 drain_local_queue(true);
2652 drain_global_stack(true);
2653
2654 // Read the note on the claim_region() method on why it might
2655 // return NULL with potentially more regions available for
2656 // claiming and why we have to check out_of_regions() to determine
2657 // whether we're done or not.
2658 while (!has_aborted() && _curr_region == NULL && !_cm->out_of_regions()) {
2659 // We are going to try to claim a new region. We should have
2660 // given up on the previous one.
2661 // Separated the asserts so that we know which one fires.
2662 assert(_curr_region == NULL, "invariant");
2663 assert(_finger == NULL, "invariant");
2664 assert(_region_limit == NULL, "invariant");
2665 HeapRegion* claimed_region = _cm->claim_region(_worker_id);
2666 if (claimed_region != NULL) {
2667 // Yes, we managed to claim one
2668 setup_for_region(claimed_region);
2669 assert(_curr_region == claimed_region, "invariant");
2670 }
2671 // It is important to call the regular clock here. It might take
2672 // a while to claim a region if, for example, we hit a large
2673 // block of empty regions. So we need to call the regular clock
2674 // method once round the loop to make sure it's called
2675 // frequently enough.
2676 regular_clock_call();
2677 }
2678
2679 if (!has_aborted() && _curr_region == NULL) {
2680 assert(_cm->out_of_regions(),
2681 "at this point we should be out of regions");
2682 }
2683 } while ( _curr_region != NULL && !has_aborted());
2684
2685 if (!has_aborted()) {
2686 // We cannot check whether the global stack is empty, since other
2687 // tasks might be pushing objects to it concurrently.
2688 assert(_cm->out_of_regions(),
2689 "at this point we should be out of regions");
2690 // Try to reduce the number of available SATB buffers so that
2691 // remark has less work to do.
2692 drain_satb_buffers();
2693 }
2694
2695 // Since we've done everything else, we can now totally drain the
2696 // local queue and global stack.
2697 drain_local_queue(false);
2698 drain_global_stack(false);
2699
2700 // Attempt at work stealing from other task's queues.
2701 if (do_stealing && !has_aborted()) {
2702 // We have not aborted. This means that we have finished all that
2703 // we could. Let's try to do some stealing...
2704
2705 // We cannot check whether the global stack is empty, since other
2706 // tasks might be pushing objects to it concurrently.
2707 assert(_cm->out_of_regions() && _task_queue->size() == 0,
2708 "only way to reach here");
2709 while (!has_aborted()) {
2710 G1TaskQueueEntry entry;
2711 if (_cm->try_stealing(_worker_id, &_hash_seed, entry)) {
2712 scan_task_entry(entry);
2713
2714 // And since we're towards the end, let's totally drain the
2715 // local queue and global stack.
2716 drain_local_queue(false);
2717 drain_global_stack(false);
2718 } else {
2719 break;
2720 }
2721 }
2722 }
2723
2724 // We still haven't aborted. Now, let's try to get into the
2725 // termination protocol.
2726 if (do_termination && !has_aborted()) {
2727 // We cannot check whether the global stack is empty, since other
2728 // tasks might be concurrently pushing objects on it.
2729 // Separated the asserts so that we know which one fires.
2730 assert(_cm->out_of_regions(), "only way to reach here");
2731 assert(_task_queue->size() == 0, "only way to reach here");
2732 _termination_start_time_ms = os::elapsedVTime() * 1000.0;
2733
2734 // The G1CMTask class also extends the TerminatorTerminator class,
2735 // hence its should_exit_termination() method will also decide
2736 // whether to exit the termination protocol or not.
2737 bool finished = (is_serial ||
2738 _cm->terminator()->offer_termination(this));
2739 double termination_end_time_ms = os::elapsedVTime() * 1000.0;
2740 _termination_time_ms +=
2741 termination_end_time_ms - _termination_start_time_ms;
2742
2743 if (finished) {
2744 // We're all done.
2745
2746 if (_worker_id == 0) {
2747 // Let's allow task 0 to do this
2748 if (_concurrent) {
2749 assert(_cm->concurrent_marking_in_progress(), "invariant");
2750 // We need to set this to false before the next
2751 // safepoint. This way we ensure that the marking phase
2752 // doesn't observe any more heap expansions.
2753 _cm->clear_concurrent_marking_in_progress();
2754 }
2755 }
2756
2757 // We can now guarantee that the global stack is empty, since
2758 // all other tasks have finished. We separated the guarantees so
2759 // that, if a condition is false, we can immediately find out
2760 // which one.
2761 guarantee(_cm->out_of_regions(), "only way to reach here");
2762 guarantee(_cm->mark_stack_empty(), "only way to reach here");
2763 guarantee(_task_queue->size() == 0, "only way to reach here");
2764 guarantee(!_cm->has_overflown(), "only way to reach here");
2765 } else {
2766 // Apparently there's more work to do. Let's abort this task. It
2767 // will restart it and we can hopefully find more things to do.
2768 set_has_aborted();
2769 }
2770 }
2771
2772 // Mainly for debugging purposes to make sure that a pointer to the
2773 // closure which was statically allocated in this frame doesn't
2774 // escape it by accident.
2775 set_cm_oop_closure(NULL);
2776 double end_time_ms = os::elapsedVTime() * 1000.0;
2777 double elapsed_time_ms = end_time_ms - _start_time_ms;
2778 // Update the step history.
2779 _step_times_ms.add(elapsed_time_ms);
2780
2781 if (has_aborted()) {
2782 // The task was aborted for some reason.
2783 if (_has_timed_out) {
2784 double diff_ms = elapsed_time_ms - _time_target_ms;
2785 // Keep statistics of how well we did with respect to hitting
2786 // our target only if we actually timed out (if we aborted for
2787 // other reasons, then the results might get skewed).
2788 _marking_step_diffs_ms.add(diff_ms);
2789 }
2790
2791 if (_cm->has_overflown()) {
2792 // This is the interesting one. We aborted because a global
2793 // overflow was raised. This means we have to restart the
2794 // marking phase and start iterating over regions. However, in
2795 // order to do this we have to make sure that all tasks stop
2796 // what they are doing and re-initialize in a safe manner. We
2797 // will achieve this with the use of two barrier sync points.
2798
2799 if (!is_serial) {
2800 // We only need to enter the sync barrier if being called
2801 // from a parallel context
2802 _cm->enter_first_sync_barrier(_worker_id);
2803
2804 // When we exit this sync barrier we know that all tasks have
2805 // stopped doing marking work. So, it's now safe to
2806 // re-initialize our data structures. At the end of this method,
2807 // task 0 will clear the global data structures.
2808 }
2809
2810 // We clear the local state of this task...
2811 clear_region_fields();
2812
2813 if (!is_serial) {
2814 // ...and enter the second barrier.
2815 _cm->enter_second_sync_barrier(_worker_id);
2816 }
2817 // At this point, if we're during the concurrent phase of
2818 // marking, everything has been re-initialized and we're
2819 // ready to restart.
2820 }
2821 }
2822 }
2823
2824 G1CMTask::G1CMTask(uint worker_id, G1ConcurrentMark* cm, G1CMTaskQueue* task_queue) :
2825 _objArray_processor(this),
2826 _worker_id(worker_id),
2827 _g1h(G1CollectedHeap::heap()),
2828 _cm(cm),
2829 _next_mark_bitmap(NULL),
2830 _task_queue(task_queue),
2831 _calls(0),
2832 _time_target_ms(0.0),
2833 _start_time_ms(0.0),
2834 _cm_oop_closure(NULL),
2835 _curr_region(NULL),
2836 _finger(NULL),
2837 _region_limit(NULL),
2838 _words_scanned(0),
2839 _words_scanned_limit(0),
2840 _real_words_scanned_limit(0),
2841 _refs_reached(0),
2842 _refs_reached_limit(0),
2843 _real_refs_reached_limit(0),
2844 _hash_seed(17),
2845 _has_aborted(false),
2846 _has_timed_out(false),
2847 _draining_satb_buffers(false),
2848 _step_times_ms(),
2849 _elapsed_time_ms(0.0),
2850 _termination_time_ms(0.0),
2851 _termination_start_time_ms(0.0),
2852 _concurrent(false),
2853 _marking_step_diffs_ms()
2854 {
2855 guarantee(task_queue != NULL, "invariant");
2856
2857 _marking_step_diffs_ms.add(0.5);
2858 }
2859
2860 // These are formatting macros that are used below to ensure
2861 // consistent formatting. The *_H_* versions are used to format the
2862 // header for a particular value and they should be kept consistent
2863 // with the corresponding macro. Also note that most of the macros add
2864 // the necessary white space (as a prefix) which makes them a bit
2865 // easier to compose.
2866
2867 // All the output lines are prefixed with this string to be able to
2868 // identify them easily in a large log file.
2869 #define G1PPRL_LINE_PREFIX "###"
2870
2871 #define G1PPRL_ADDR_BASE_FORMAT " " PTR_FORMAT "-" PTR_FORMAT
2872 #ifdef _LP64
2873 #define G1PPRL_ADDR_BASE_H_FORMAT " %37s"
2874 #else // _LP64
2875 #define G1PPRL_ADDR_BASE_H_FORMAT " %21s"
2876 #endif // _LP64
2877
2878 // For per-region info
2879 #define G1PPRL_TYPE_FORMAT " %-4s"
2880 #define G1PPRL_TYPE_H_FORMAT " %4s"
2881 #define G1PPRL_BYTE_FORMAT " " SIZE_FORMAT_W(9)
2882 #define G1PPRL_BYTE_H_FORMAT " %9s"
2883 #define G1PPRL_DOUBLE_FORMAT " %14.1f"
2884 #define G1PPRL_DOUBLE_H_FORMAT " %14s"
2885
2886 // For summary info
2887 #define G1PPRL_SUM_ADDR_FORMAT(tag) " " tag ":" G1PPRL_ADDR_BASE_FORMAT
2888 #define G1PPRL_SUM_BYTE_FORMAT(tag) " " tag ": " SIZE_FORMAT
2889 #define G1PPRL_SUM_MB_FORMAT(tag) " " tag ": %1.2f MB"
2890 #define G1PPRL_SUM_MB_PERC_FORMAT(tag) G1PPRL_SUM_MB_FORMAT(tag) " / %1.2f %%"
2891
2892 G1PrintRegionLivenessInfoClosure::G1PrintRegionLivenessInfoClosure(const char* phase_name) :
2893 _total_used_bytes(0), _total_capacity_bytes(0),
2894 _total_prev_live_bytes(0), _total_next_live_bytes(0),
2895 _total_remset_bytes(0), _total_strong_code_roots_bytes(0)
2896 {
2897 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2898 MemRegion g1_reserved = g1h->g1_reserved();
2899 double now = os::elapsedTime();
2900
2901 // Print the header of the output.
2902 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX" PHASE %s @ %1.3f", phase_name, now);
2903 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX" HEAP"
2904 G1PPRL_SUM_ADDR_FORMAT("reserved")
2905 G1PPRL_SUM_BYTE_FORMAT("region-size"),
2906 p2i(g1_reserved.start()), p2i(g1_reserved.end()),
2907 HeapRegion::GrainBytes);
2908 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX);
2909 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX
2910 G1PPRL_TYPE_H_FORMAT
2911 G1PPRL_ADDR_BASE_H_FORMAT
2912 G1PPRL_BYTE_H_FORMAT
2913 G1PPRL_BYTE_H_FORMAT
2914 G1PPRL_BYTE_H_FORMAT
2915 G1PPRL_DOUBLE_H_FORMAT
2916 G1PPRL_BYTE_H_FORMAT
2917 G1PPRL_BYTE_H_FORMAT,
2918 "type", "address-range",
2919 "used", "prev-live", "next-live", "gc-eff",
2920 "remset", "code-roots");
2921 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX
2922 G1PPRL_TYPE_H_FORMAT
2923 G1PPRL_ADDR_BASE_H_FORMAT
2924 G1PPRL_BYTE_H_FORMAT
2925 G1PPRL_BYTE_H_FORMAT
2926 G1PPRL_BYTE_H_FORMAT
2927 G1PPRL_DOUBLE_H_FORMAT
2928 G1PPRL_BYTE_H_FORMAT
2929 G1PPRL_BYTE_H_FORMAT,
2930 "", "",
2931 "(bytes)", "(bytes)", "(bytes)", "(bytes/ms)",
2932 "(bytes)", "(bytes)");
2933 }
2934
2935 bool G1PrintRegionLivenessInfoClosure::doHeapRegion(HeapRegion* r) {
2936 const char* type = r->get_type_str();
2937 HeapWord* bottom = r->bottom();
2938 HeapWord* end = r->end();
2939 size_t capacity_bytes = r->capacity();
2940 size_t used_bytes = r->used();
2941 size_t prev_live_bytes = r->live_bytes();
2942 size_t next_live_bytes = r->next_live_bytes();
2943 double gc_eff = r->gc_efficiency();
2944 size_t remset_bytes = r->rem_set()->mem_size();
2945 size_t strong_code_roots_bytes = r->rem_set()->strong_code_roots_mem_size();
2946
2947 _total_used_bytes += used_bytes;
2948 _total_capacity_bytes += capacity_bytes;
2949 _total_prev_live_bytes += prev_live_bytes;
2950 _total_next_live_bytes += next_live_bytes;
2951 _total_remset_bytes += remset_bytes;
2952 _total_strong_code_roots_bytes += strong_code_roots_bytes;
2953
2954 // Print a line for this particular region.
2955 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX
2956 G1PPRL_TYPE_FORMAT
2957 G1PPRL_ADDR_BASE_FORMAT
2958 G1PPRL_BYTE_FORMAT
2959 G1PPRL_BYTE_FORMAT
2960 G1PPRL_BYTE_FORMAT
2961 G1PPRL_DOUBLE_FORMAT
2962 G1PPRL_BYTE_FORMAT
2963 G1PPRL_BYTE_FORMAT,
2964 type, p2i(bottom), p2i(end),
2965 used_bytes, prev_live_bytes, next_live_bytes, gc_eff,
2966 remset_bytes, strong_code_roots_bytes);
2967
2968 return false;
2969 }
2970
2971 G1PrintRegionLivenessInfoClosure::~G1PrintRegionLivenessInfoClosure() {
2972 // add static memory usages to remembered set sizes
2973 _total_remset_bytes += HeapRegionRemSet::fl_mem_size() + HeapRegionRemSet::static_mem_size();
2974 // Print the footer of the output.
2975 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX);
2976 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX
2977 " SUMMARY"
2978 G1PPRL_SUM_MB_FORMAT("capacity")
2979 G1PPRL_SUM_MB_PERC_FORMAT("used")
2980 G1PPRL_SUM_MB_PERC_FORMAT("prev-live")
2981 G1PPRL_SUM_MB_PERC_FORMAT("next-live")
2982 G1PPRL_SUM_MB_FORMAT("remset")
2983 G1PPRL_SUM_MB_FORMAT("code-roots"),
2984 bytes_to_mb(_total_capacity_bytes),
2985 bytes_to_mb(_total_used_bytes),
2986 percent_of(_total_used_bytes, _total_capacity_bytes),
2987 bytes_to_mb(_total_prev_live_bytes),
2988 percent_of(_total_prev_live_bytes, _total_capacity_bytes),
2989 bytes_to_mb(_total_next_live_bytes),
2990 percent_of(_total_next_live_bytes, _total_capacity_bytes),
2991 bytes_to_mb(_total_remset_bytes),
2992 bytes_to_mb(_total_strong_code_roots_bytes));
2993 }