1 /*
2 * Copyright (c) 2001, 2018, 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/g1OopClosures.inline.hpp"
34 #include "gc/g1/g1Policy.hpp"
35 #include "gc/g1/g1RegionMarkStatsCache.inline.hpp"
36 #include "gc/g1/g1StringDedup.hpp"
37 #include "gc/g1/heapRegion.inline.hpp"
38 #include "gc/g1/heapRegionRemSet.hpp"
39 #include "gc/g1/heapRegionSet.inline.hpp"
40 #include "gc/shared/adaptiveSizePolicy.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 "include/jvm.h"
53 #include "logging/log.hpp"
54 #include "memory/allocation.hpp"
55 #include "memory/resourceArea.hpp"
56 #include "oops/access.inline.hpp"
57 #include "oops/oop.inline.hpp"
58 #include "runtime/atomic.hpp"
59 #include "runtime/handles.inline.hpp"
60 #include "runtime/java.hpp"
61 #include "runtime/prefetch.inline.hpp"
62 #include "services/memTracker.hpp"
63 #include "utilities/align.hpp"
64 #include "utilities/growableArray.hpp"
65
66 bool G1CMBitMapClosure::do_addr(HeapWord* const addr) {
67 assert(addr < _cm->finger(), "invariant");
68 assert(addr >= _task->finger(), "invariant");
69
70 // We move that task's local finger along.
71 _task->move_finger_to(addr);
72
73 _task->scan_task_entry(G1TaskQueueEntry::from_oop(oop(addr)));
74 // we only partially drain the local queue and global stack
75 _task->drain_local_queue(true);
76 _task->drain_global_stack(true);
77
78 // if the has_aborted flag has been raised, we need to bail out of
79 // the iteration
80 return !_task->has_aborted();
81 }
82
83 G1CMMarkStack::G1CMMarkStack() :
84 _max_chunk_capacity(0),
85 _base(NULL),
86 _chunk_capacity(0) {
87 set_empty();
88 }
89
90 bool G1CMMarkStack::resize(size_t new_capacity) {
91 assert(is_empty(), "Only resize when stack is empty.");
92 assert(new_capacity <= _max_chunk_capacity,
93 "Trying to resize stack to " SIZE_FORMAT " chunks when the maximum is " SIZE_FORMAT, new_capacity, _max_chunk_capacity);
94
95 TaskQueueEntryChunk* new_base = MmapArrayAllocator<TaskQueueEntryChunk>::allocate_or_null(new_capacity, mtGC);
96
97 if (new_base == NULL) {
98 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));
99 return false;
100 }
101 // Release old mapping.
102 if (_base != NULL) {
103 MmapArrayAllocator<TaskQueueEntryChunk>::free(_base, _chunk_capacity);
104 }
105
106 _base = new_base;
107 _chunk_capacity = new_capacity;
108 set_empty();
109
110 return true;
111 }
112
113 size_t G1CMMarkStack::capacity_alignment() {
114 return (size_t)lcm(os::vm_allocation_granularity(), sizeof(TaskQueueEntryChunk)) / sizeof(G1TaskQueueEntry);
115 }
116
117 bool G1CMMarkStack::initialize(size_t initial_capacity, size_t max_capacity) {
118 guarantee(_max_chunk_capacity == 0, "G1CMMarkStack already initialized.");
119
120 size_t const TaskEntryChunkSizeInVoidStar = sizeof(TaskQueueEntryChunk) / sizeof(G1TaskQueueEntry);
121
122 _max_chunk_capacity = align_up(max_capacity, capacity_alignment()) / TaskEntryChunkSizeInVoidStar;
123 size_t initial_chunk_capacity = align_up(initial_capacity, capacity_alignment()) / TaskEntryChunkSizeInVoidStar;
124
125 guarantee(initial_chunk_capacity <= _max_chunk_capacity,
126 "Maximum chunk capacity " SIZE_FORMAT " smaller than initial capacity " SIZE_FORMAT,
127 _max_chunk_capacity,
128 initial_chunk_capacity);
129
130 log_debug(gc)("Initialize mark stack with " SIZE_FORMAT " chunks, maximum " SIZE_FORMAT,
131 initial_chunk_capacity, _max_chunk_capacity);
132
133 return resize(initial_chunk_capacity);
134 }
135
136 void G1CMMarkStack::expand() {
137 if (_chunk_capacity == _max_chunk_capacity) {
138 log_debug(gc)("Can not expand overflow mark stack further, already at maximum capacity of " SIZE_FORMAT " chunks.", _chunk_capacity);
139 return;
140 }
141 size_t old_capacity = _chunk_capacity;
142 // Double capacity if possible
143 size_t new_capacity = MIN2(old_capacity * 2, _max_chunk_capacity);
144
145 if (resize(new_capacity)) {
146 log_debug(gc)("Expanded mark stack capacity from " SIZE_FORMAT " to " SIZE_FORMAT " chunks",
147 old_capacity, new_capacity);
148 } else {
149 log_warning(gc)("Failed to expand mark stack capacity from " SIZE_FORMAT " to " SIZE_FORMAT " chunks",
150 old_capacity, new_capacity);
151 }
152 }
153
154 G1CMMarkStack::~G1CMMarkStack() {
155 if (_base != NULL) {
156 MmapArrayAllocator<TaskQueueEntryChunk>::free(_base, _chunk_capacity);
157 }
158 }
159
160 void G1CMMarkStack::add_chunk_to_list(TaskQueueEntryChunk* volatile* list, TaskQueueEntryChunk* elem) {
161 elem->next = *list;
162 *list = elem;
163 }
164
165 void G1CMMarkStack::add_chunk_to_chunk_list(TaskQueueEntryChunk* elem) {
166 MutexLockerEx x(MarkStackChunkList_lock, Mutex::_no_safepoint_check_flag);
167 add_chunk_to_list(&_chunk_list, elem);
168 _chunks_in_chunk_list++;
169 }
170
171 void G1CMMarkStack::add_chunk_to_free_list(TaskQueueEntryChunk* elem) {
172 MutexLockerEx x(MarkStackFreeList_lock, Mutex::_no_safepoint_check_flag);
173 add_chunk_to_list(&_free_list, elem);
174 }
175
176 G1CMMarkStack::TaskQueueEntryChunk* G1CMMarkStack::remove_chunk_from_list(TaskQueueEntryChunk* volatile* list) {
177 TaskQueueEntryChunk* result = *list;
178 if (result != NULL) {
179 *list = (*list)->next;
180 }
181 return result;
182 }
183
184 G1CMMarkStack::TaskQueueEntryChunk* G1CMMarkStack::remove_chunk_from_chunk_list() {
185 MutexLockerEx x(MarkStackChunkList_lock, Mutex::_no_safepoint_check_flag);
186 TaskQueueEntryChunk* result = remove_chunk_from_list(&_chunk_list);
187 if (result != NULL) {
188 _chunks_in_chunk_list--;
189 }
190 return result;
191 }
192
193 G1CMMarkStack::TaskQueueEntryChunk* G1CMMarkStack::remove_chunk_from_free_list() {
194 MutexLockerEx x(MarkStackFreeList_lock, Mutex::_no_safepoint_check_flag);
195 return remove_chunk_from_list(&_free_list);
196 }
197
198 G1CMMarkStack::TaskQueueEntryChunk* G1CMMarkStack::allocate_new_chunk() {
199 // This dirty read of _hwm is okay because we only ever increase the _hwm in parallel code.
200 // Further this limits _hwm to a value of _chunk_capacity + #threads, avoiding
201 // wraparound of _hwm.
202 if (_hwm >= _chunk_capacity) {
203 return NULL;
204 }
205
206 size_t cur_idx = Atomic::add(1u, &_hwm) - 1;
207 if (cur_idx >= _chunk_capacity) {
208 return NULL;
209 }
210
211 TaskQueueEntryChunk* result = ::new (&_base[cur_idx]) TaskQueueEntryChunk;
212 result->next = NULL;
213 return result;
214 }
215
216 bool G1CMMarkStack::par_push_chunk(G1TaskQueueEntry* ptr_arr) {
217 // Get a new chunk.
218 TaskQueueEntryChunk* new_chunk = remove_chunk_from_free_list();
219
220 if (new_chunk == NULL) {
221 // Did not get a chunk from the free list. Allocate from backing memory.
222 new_chunk = allocate_new_chunk();
223
224 if (new_chunk == NULL) {
225 return false;
226 }
227 }
228
229 Copy::conjoint_memory_atomic(ptr_arr, new_chunk->data, EntriesPerChunk * sizeof(G1TaskQueueEntry));
230
231 add_chunk_to_chunk_list(new_chunk);
232
233 return true;
234 }
235
236 bool G1CMMarkStack::par_pop_chunk(G1TaskQueueEntry* ptr_arr) {
237 TaskQueueEntryChunk* cur = remove_chunk_from_chunk_list();
238
239 if (cur == NULL) {
240 return false;
241 }
242
243 Copy::conjoint_memory_atomic(cur->data, ptr_arr, EntriesPerChunk * sizeof(G1TaskQueueEntry));
244
245 add_chunk_to_free_list(cur);
246 return true;
247 }
248
249 void G1CMMarkStack::set_empty() {
250 _chunks_in_chunk_list = 0;
251 _hwm = 0;
252 _chunk_list = NULL;
253 _free_list = NULL;
254 }
255
256 G1CMRootRegions::G1CMRootRegions() :
257 _survivors(NULL), _cm(NULL), _scan_in_progress(false),
258 _should_abort(false), _claimed_survivor_index(0) { }
259
260 void G1CMRootRegions::init(const G1SurvivorRegions* survivors, G1ConcurrentMark* cm) {
261 _survivors = survivors;
262 _cm = cm;
263 }
264
265 void G1CMRootRegions::prepare_for_scan() {
266 assert(!scan_in_progress(), "pre-condition");
267
268 // Currently, only survivors can be root regions.
269 _claimed_survivor_index = 0;
270 _scan_in_progress = _survivors->regions()->is_nonempty();
271 _should_abort = false;
272 }
273
274 HeapRegion* G1CMRootRegions::claim_next() {
275 if (_should_abort) {
276 // If someone has set the should_abort flag, we return NULL to
277 // force the caller to bail out of their loop.
278 return NULL;
279 }
280
281 // Currently, only survivors can be root regions.
282 const GrowableArray<HeapRegion*>* survivor_regions = _survivors->regions();
283
284 int claimed_index = Atomic::add(1, &_claimed_survivor_index) - 1;
285 if (claimed_index < survivor_regions->length()) {
286 return survivor_regions->at(claimed_index);
287 }
288 return NULL;
289 }
290
291 uint G1CMRootRegions::num_root_regions() const {
292 return (uint)_survivors->regions()->length();
293 }
294
295 void G1CMRootRegions::notify_scan_done() {
296 MutexLockerEx x(RootRegionScan_lock, Mutex::_no_safepoint_check_flag);
297 _scan_in_progress = false;
298 RootRegionScan_lock->notify_all();
299 }
300
301 void G1CMRootRegions::cancel_scan() {
302 notify_scan_done();
303 }
304
305 void G1CMRootRegions::scan_finished() {
306 assert(scan_in_progress(), "pre-condition");
307
308 // Currently, only survivors can be root regions.
309 if (!_should_abort) {
310 assert(_claimed_survivor_index >= 0, "otherwise comparison is invalid: %d", _claimed_survivor_index);
311 assert((uint)_claimed_survivor_index >= _survivors->length(),
312 "we should have claimed all survivors, claimed index = %u, length = %u",
313 (uint)_claimed_survivor_index, _survivors->length());
314 }
315
316 notify_scan_done();
317 }
318
319 bool G1CMRootRegions::wait_until_scan_finished() {
320 if (!scan_in_progress()) {
321 return false;
322 }
323
324 {
325 MutexLockerEx x(RootRegionScan_lock, Mutex::_no_safepoint_check_flag);
326 while (scan_in_progress()) {
327 RootRegionScan_lock->wait(Mutex::_no_safepoint_check_flag);
328 }
329 }
330 return true;
331 }
332
333 // Returns the maximum number of workers to be used in a concurrent
334 // phase based on the number of GC workers being used in a STW
335 // phase.
336 static uint scale_concurrent_worker_threads(uint num_gc_workers) {
337 return MAX2((num_gc_workers + 2) / 4, 1U);
338 }
339
340 G1ConcurrentMark::G1ConcurrentMark(G1CollectedHeap* g1h,
341 G1RegionToSpaceMapper* prev_bitmap_storage,
342 G1RegionToSpaceMapper* next_bitmap_storage) :
343 // _cm_thread set inside the constructor
344 _g1h(g1h),
345 _completed_initialization(false),
346
347 _mark_bitmap_1(),
348 _mark_bitmap_2(),
349 _prev_mark_bitmap(&_mark_bitmap_1),
350 _next_mark_bitmap(&_mark_bitmap_2),
351
352 _heap(_g1h->reserved_region()),
353
354 _root_regions(),
355
356 _global_mark_stack(),
357
358 // _finger set in set_non_marking_state
359
360 _worker_id_offset(DirtyCardQueueSet::num_par_ids() + G1ConcRefinementThreads),
361 _max_num_tasks(ParallelGCThreads),
362 // _num_active_tasks set in set_non_marking_state()
363 // _tasks set inside the constructor
364
365 _task_queues(new G1CMTaskQueueSet((int) _max_num_tasks)),
366 _terminator(ParallelTaskTerminator((int) _max_num_tasks, _task_queues)),
367
368 _first_overflow_barrier_sync(),
369 _second_overflow_barrier_sync(),
370
371 _has_overflown(false),
372 _concurrent(false),
373 _has_aborted(false),
374 _restart_for_overflow(false),
375 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
376 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()),
377
378 // _verbose_level set below
379
380 _init_times(),
381 _remark_times(),
382 _remark_mark_times(),
383 _remark_weak_ref_times(),
384 _cleanup_times(),
385 _total_cleanup_time(0.0),
386
387 _accum_task_vtime(NULL),
388
389 _concurrent_workers(NULL),
390 _num_concurrent_workers(0),
391 _max_concurrent_workers(0),
392
393 _region_mark_stats(NEW_C_HEAP_ARRAY(G1RegionMarkStats, _g1h->max_regions(), mtGC)),
394 _top_at_rebuild_starts(NEW_C_HEAP_ARRAY(HeapWord*, _g1h->max_regions(), mtGC))
395 {
396 _mark_bitmap_1.initialize(g1h->reserved_region(), prev_bitmap_storage);
397 _mark_bitmap_2.initialize(g1h->reserved_region(), next_bitmap_storage);
398
399 // Create & start ConcurrentMark thread.
400 _cm_thread = new ConcurrentMarkThread(this);
401 if (_cm_thread->osthread() == NULL) {
402 vm_shutdown_during_initialization("Could not create ConcurrentMarkThread");
403 }
404
405 assert(CGC_lock != NULL, "CGC_lock must be initialized");
406
407 SATBMarkQueueSet& satb_qs = JavaThread::satb_mark_queue_set();
408 satb_qs.set_buffer_size(G1SATBBufferSize);
409
410 _root_regions.init(_g1h->survivor(), this);
411
412 if (FLAG_IS_DEFAULT(ConcGCThreads) || ConcGCThreads == 0) {
413 // Calculate the number of concurrent worker threads by scaling
414 // the number of parallel GC threads.
415 uint marking_thread_num = scale_concurrent_worker_threads(ParallelGCThreads);
416 FLAG_SET_ERGO(uint, ConcGCThreads, marking_thread_num);
417 }
418
419 assert(ConcGCThreads > 0, "ConcGCThreads have been set.");
420 if (ConcGCThreads > ParallelGCThreads) {
421 log_warning(gc)("More ConcGCThreads (%u) than ParallelGCThreads (%u).",
422 ConcGCThreads, ParallelGCThreads);
423 return;
424 }
425
426 log_debug(gc)("ConcGCThreads: %u offset %u", ConcGCThreads, _worker_id_offset);
427 log_debug(gc)("ParallelGCThreads: %u", ParallelGCThreads);
428
429 _num_concurrent_workers = ConcGCThreads;
430 _max_concurrent_workers = _num_concurrent_workers;
431
432 _concurrent_workers = new WorkGang("G1 Conc", _max_concurrent_workers, false, true);
433 _concurrent_workers->initialize_workers();
434
435 if (FLAG_IS_DEFAULT(MarkStackSize)) {
436 size_t mark_stack_size =
437 MIN2(MarkStackSizeMax,
438 MAX2(MarkStackSize, (size_t) (_max_concurrent_workers * TASKQUEUE_SIZE)));
439 // Verify that the calculated value for MarkStackSize is in range.
440 // It would be nice to use the private utility routine from Arguments.
441 if (!(mark_stack_size >= 1 && mark_stack_size <= MarkStackSizeMax)) {
442 log_warning(gc)("Invalid value calculated for MarkStackSize (" SIZE_FORMAT "): "
443 "must be between 1 and " SIZE_FORMAT,
444 mark_stack_size, MarkStackSizeMax);
445 return;
446 }
447 FLAG_SET_ERGO(size_t, MarkStackSize, mark_stack_size);
448 } else {
449 // Verify MarkStackSize is in range.
450 if (FLAG_IS_CMDLINE(MarkStackSize)) {
451 if (FLAG_IS_DEFAULT(MarkStackSizeMax)) {
452 if (!(MarkStackSize >= 1 && MarkStackSize <= MarkStackSizeMax)) {
453 log_warning(gc)("Invalid value specified for MarkStackSize (" SIZE_FORMAT "): "
454 "must be between 1 and " SIZE_FORMAT,
455 MarkStackSize, MarkStackSizeMax);
456 return;
457 }
458 } else if (FLAG_IS_CMDLINE(MarkStackSizeMax)) {
459 if (!(MarkStackSize >= 1 && MarkStackSize <= MarkStackSizeMax)) {
460 log_warning(gc)("Invalid value specified for MarkStackSize (" SIZE_FORMAT ")"
461 " or for MarkStackSizeMax (" SIZE_FORMAT ")",
462 MarkStackSize, MarkStackSizeMax);
463 return;
464 }
465 }
466 }
467 }
468
469 if (!_global_mark_stack.initialize(MarkStackSize, MarkStackSizeMax)) {
470 vm_exit_during_initialization("Failed to allocate initial concurrent mark overflow mark stack.");
471 }
472
473 _tasks = NEW_C_HEAP_ARRAY(G1CMTask*, _max_num_tasks, mtGC);
474 _accum_task_vtime = NEW_C_HEAP_ARRAY(double, _max_num_tasks, mtGC);
475
476 // so that the assertion in MarkingTaskQueue::task_queue doesn't fail
477 _num_active_tasks = _max_num_tasks;
478
479 for (uint i = 0; i < _max_num_tasks; ++i) {
480 G1CMTaskQueue* task_queue = new G1CMTaskQueue();
481 task_queue->initialize();
482 _task_queues->register_queue(i, task_queue);
483
484 _tasks[i] = new G1CMTask(i, this, task_queue, _region_mark_stats, _g1h->max_regions());
485
486 _accum_task_vtime[i] = 0.0;
487 }
488
489 reset_at_marking_complete();
490 _completed_initialization = true;
491 }
492
493 void G1ConcurrentMark::reset() {
494 _has_aborted = false;
495
496 reset_marking_for_restart();
497
498 // Reset all tasks, since different phases will use different number of active
499 // threads. So, it's easiest to have all of them ready.
500 for (uint i = 0; i < _max_num_tasks; ++i) {
501 _tasks[i]->reset(_next_mark_bitmap);
502 }
503
504 uint max_regions = _g1h->max_regions();
505 for (uint i = 0; i < max_regions; i++) {
506 _top_at_rebuild_starts[i] = NULL;
507 _region_mark_stats[i].clear();
508 }
509 }
510
511 void G1ConcurrentMark::clear_statistics_in_region(uint region_idx) {
512 for (uint j = 0; j < _max_num_tasks; ++j) {
513 _tasks[j]->clear_mark_stats_cache(region_idx);
514 }
515 _top_at_rebuild_starts[region_idx] = NULL;
516 _region_mark_stats[region_idx].clear();
517 }
518
519 void G1ConcurrentMark::clear_statistics(HeapRegion* r) {
520 uint const region_idx = r->hrm_index();
521 if (r->is_humongous()) {
522 assert(r->is_starts_humongous(), "Got humongous continues region here");
523 uint const size_in_regions = (uint)_g1h->humongous_obj_size_in_regions(oop(r->humongous_start_region()->bottom())->size());
524 for (uint j = region_idx; j < (region_idx + size_in_regions); j++) {
525 clear_statistics_in_region(j);
526 }
527 } else {
528 clear_statistics_in_region(region_idx);
529 }
530 }
531
532 static void maybe_clear_bitmap_if_set(G1CMBitMap* bitmap, HeapWord* addr) {
533 if (bitmap->is_marked(addr)) {
534 bitmap->clear(addr);
535 }
536 }
537
538 void G1ConcurrentMark::humongous_object_eagerly_reclaimed(HeapRegion* r) {
539 assert_at_safepoint_on_vm_thread();
540
541 // Need to clear all mark bits of the humongous object.
542 maybe_clear_bitmap_if_set(_prev_mark_bitmap, r->bottom());
543
544 G1CollectorState* collector_state = _g1h->collector_state();
545 if (collector_state->mark_or_rebuild_in_progress() ||
546 collector_state->clearing_next_bitmap()) {
547 maybe_clear_bitmap_if_set(_next_mark_bitmap, r->bottom());
548 }
549
550 // Clear any statistics about the region gathered so far.
551 clear_statistics(r);
552 }
553
554 void G1ConcurrentMark::reset_marking_for_restart() {
555 _global_mark_stack.set_empty();
556
557 // Expand the marking stack, if we have to and if we can.
558 if (has_overflown()) {
559 _global_mark_stack.expand();
560
561 uint max_regions = _g1h->max_regions();
562 for (uint i = 0; i < max_regions; i++) {
563 _region_mark_stats[i].clear_during_overflow();
564 }
565 }
566
567 clear_has_overflown();
568 _finger = _heap.start();
569
570 for (uint i = 0; i < _max_num_tasks; ++i) {
571 G1CMTaskQueue* queue = _task_queues->queue(i);
572 queue->set_empty();
573 }
574 }
575
576 void G1ConcurrentMark::set_concurrency(uint active_tasks) {
577 assert(active_tasks <= _max_num_tasks, "we should not have more");
578
579 _num_active_tasks = active_tasks;
580 // Need to update the three data structures below according to the
581 // number of active threads for this phase.
582 _terminator = ParallelTaskTerminator((int) active_tasks, _task_queues);
583 _first_overflow_barrier_sync.set_n_workers((int) active_tasks);
584 _second_overflow_barrier_sync.set_n_workers((int) active_tasks);
585 }
586
587 void G1ConcurrentMark::set_concurrency_and_phase(uint active_tasks, bool concurrent) {
588 set_concurrency(active_tasks);
589
590 _concurrent = concurrent;
591
592 if (!concurrent) {
593 // At this point we should be in a STW phase, and completed marking.
594 assert_at_safepoint_on_vm_thread();
595 assert(out_of_regions(),
596 "only way to get here: _finger: " PTR_FORMAT ", _heap_end: " PTR_FORMAT,
597 p2i(_finger), p2i(_heap.end()));
598 }
599 }
600
601 void G1ConcurrentMark::reset_at_marking_complete() {
602 // We set the global marking state to some default values when we're
603 // not doing marking.
604 reset_marking_for_restart();
605 _num_active_tasks = 0;
606 }
607
608 G1ConcurrentMark::~G1ConcurrentMark() {
609 FREE_C_HEAP_ARRAY(HeapWord*, _top_at_rebuild_starts);
610 FREE_C_HEAP_ARRAY(G1RegionMarkStats, _region_mark_stats);
611 // The G1ConcurrentMark instance is never freed.
612 ShouldNotReachHere();
613 }
614
615 class G1ClearBitMapTask : public AbstractGangTask {
616 public:
617 static size_t chunk_size() { return M; }
618
619 private:
620 // Heap region closure used for clearing the given mark bitmap.
621 class G1ClearBitmapHRClosure : public HeapRegionClosure {
622 private:
623 G1CMBitMap* _bitmap;
624 G1ConcurrentMark* _cm;
625 public:
626 G1ClearBitmapHRClosure(G1CMBitMap* bitmap, G1ConcurrentMark* cm) : HeapRegionClosure(), _cm(cm), _bitmap(bitmap) {
627 }
628
629 virtual bool do_heap_region(HeapRegion* r) {
630 size_t const chunk_size_in_words = G1ClearBitMapTask::chunk_size() / HeapWordSize;
631
632 HeapWord* cur = r->bottom();
633 HeapWord* const end = r->end();
634
635 while (cur < end) {
636 MemRegion mr(cur, MIN2(cur + chunk_size_in_words, end));
637 _bitmap->clear_range(mr);
638
639 cur += chunk_size_in_words;
640
641 // Abort iteration if after yielding the marking has been aborted.
642 if (_cm != NULL && _cm->do_yield_check() && _cm->has_aborted()) {
643 return true;
644 }
645 // Repeat the asserts from before the start of the closure. We will do them
646 // as asserts here to minimize their overhead on the product. However, we
647 // will have them as guarantees at the beginning / end of the bitmap
648 // clearing to get some checking in the product.
649 assert(_cm == NULL || _cm->cm_thread()->during_cycle(), "invariant");
650 assert(_cm == NULL || !G1CollectedHeap::heap()->collector_state()->mark_or_rebuild_in_progress(), "invariant");
651 }
652 assert(cur == end, "Must have completed iteration over the bitmap for region %u.", r->hrm_index());
653
654 return false;
655 }
656 };
657
658 G1ClearBitmapHRClosure _cl;
659 HeapRegionClaimer _hr_claimer;
660 bool _suspendible; // If the task is suspendible, workers must join the STS.
661
662 public:
663 G1ClearBitMapTask(G1CMBitMap* bitmap, G1ConcurrentMark* cm, uint n_workers, bool suspendible) :
664 AbstractGangTask("G1 Clear Bitmap"),
665 _cl(bitmap, suspendible ? cm : NULL),
666 _hr_claimer(n_workers),
667 _suspendible(suspendible)
668 { }
669
670 void work(uint worker_id) {
671 SuspendibleThreadSetJoiner sts_join(_suspendible);
672 G1CollectedHeap::heap()->heap_region_par_iterate_from_worker_offset(&_cl, &_hr_claimer, worker_id);
673 }
674
675 bool is_complete() {
676 return _cl.is_complete();
677 }
678 };
679
680 void G1ConcurrentMark::clear_bitmap(G1CMBitMap* bitmap, WorkGang* workers, bool may_yield) {
681 assert(may_yield || SafepointSynchronize::is_at_safepoint(), "Non-yielding bitmap clear only allowed at safepoint.");
682
683 size_t const num_bytes_to_clear = (HeapRegion::GrainBytes * _g1h->num_regions()) / G1CMBitMap::heap_map_factor();
684 size_t const num_chunks = align_up(num_bytes_to_clear, G1ClearBitMapTask::chunk_size()) / G1ClearBitMapTask::chunk_size();
685
686 uint const num_workers = (uint)MIN2(num_chunks, (size_t)workers->active_workers());
687
688 G1ClearBitMapTask cl(bitmap, this, num_workers, may_yield);
689
690 log_debug(gc, ergo)("Running %s with %u workers for " SIZE_FORMAT " work units.", cl.name(), num_workers, num_chunks);
691 workers->run_task(&cl, num_workers);
692 guarantee(!may_yield || cl.is_complete(), "Must have completed iteration when not yielding.");
693 }
694
695 void G1ConcurrentMark::cleanup_for_next_mark() {
696 // Make sure that the concurrent mark thread looks to still be in
697 // the current cycle.
698 guarantee(cm_thread()->during_cycle(), "invariant");
699
700 // We are finishing up the current cycle by clearing the next
701 // marking bitmap and getting it ready for the next cycle. During
702 // this time no other cycle can start. So, let's make sure that this
703 // is the case.
704 guarantee(!_g1h->collector_state()->mark_or_rebuild_in_progress(), "invariant");
705
706 clear_bitmap(_next_mark_bitmap, _concurrent_workers, true);
707
708 // Repeat the asserts from above.
709 guarantee(cm_thread()->during_cycle(), "invariant");
710 guarantee(!_g1h->collector_state()->mark_or_rebuild_in_progress(), "invariant");
711 }
712
713 void G1ConcurrentMark::clear_prev_bitmap(WorkGang* workers) {
714 assert_at_safepoint_on_vm_thread();
715 clear_bitmap(_prev_mark_bitmap, workers, false);
716 }
717
718 class CheckBitmapClearHRClosure : public HeapRegionClosure {
719 G1CMBitMap* _bitmap;
720 public:
721 CheckBitmapClearHRClosure(G1CMBitMap* bitmap) : _bitmap(bitmap) {
722 }
723
724 virtual bool do_heap_region(HeapRegion* r) {
725 // This closure can be called concurrently to the mutator, so we must make sure
726 // that the result of the getNextMarkedWordAddress() call is compared to the
727 // value passed to it as limit to detect any found bits.
728 // end never changes in G1.
729 HeapWord* end = r->end();
730 return _bitmap->get_next_marked_addr(r->bottom(), end) != end;
731 }
732 };
733
734 bool G1ConcurrentMark::next_mark_bitmap_is_clear() {
735 CheckBitmapClearHRClosure cl(_next_mark_bitmap);
736 _g1h->heap_region_iterate(&cl);
737 return cl.is_complete();
738 }
739
740 class NoteStartOfMarkHRClosure : public HeapRegionClosure {
741 public:
742 bool do_heap_region(HeapRegion* r) {
743 r->note_start_of_marking();
744 return false;
745 }
746 };
747
748 void G1ConcurrentMark::pre_initial_mark() {
749 // Initialize marking structures. This has to be done in a STW phase.
750 reset();
751
752 // For each region note start of marking.
753 NoteStartOfMarkHRClosure startcl;
754 _g1h->heap_region_iterate(&startcl);
755 }
756
757
758 void G1ConcurrentMark::post_initial_mark() {
759 // Start Concurrent Marking weak-reference discovery.
760 ReferenceProcessor* rp = _g1h->ref_processor_cm();
761 // enable ("weak") refs discovery
762 rp->enable_discovery();
763 rp->setup_policy(false); // snapshot the soft ref policy to be used in this cycle
764
765 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
766 // This is the start of the marking cycle, we're expected all
767 // threads to have SATB queues with active set to false.
768 satb_mq_set.set_active_all_threads(true, /* new active value */
769 false /* expected_active */);
770
771 _root_regions.prepare_for_scan();
772
773 // update_g1_committed() will be called at the end of an evac pause
774 // when marking is on. So, it's also called at the end of the
775 // initial-mark pause to update the heap end, if the heap expands
776 // during it. No need to call it here.
777 }
778
779 /*
780 * Notice that in the next two methods, we actually leave the STS
781 * during the barrier sync and join it immediately afterwards. If we
782 * do not do this, the following deadlock can occur: one thread could
783 * be in the barrier sync code, waiting for the other thread to also
784 * sync up, whereas another one could be trying to yield, while also
785 * waiting for the other threads to sync up too.
786 *
787 * Note, however, that this code is also used during remark and in
788 * this case we should not attempt to leave / enter the STS, otherwise
789 * we'll either hit an assert (debug / fastdebug) or deadlock
790 * (product). So we should only leave / enter the STS if we are
791 * operating concurrently.
792 *
793 * Because the thread that does the sync barrier has left the STS, it
794 * is possible to be suspended for a Full GC or an evacuation pause
795 * could occur. This is actually safe, since the entering the sync
796 * barrier is one of the last things do_marking_step() does, and it
797 * doesn't manipulate any data structures afterwards.
798 */
799
800 void G1ConcurrentMark::enter_first_sync_barrier(uint worker_id) {
801 bool barrier_aborted;
802 {
803 SuspendibleThreadSetLeaver sts_leave(concurrent());
804 barrier_aborted = !_first_overflow_barrier_sync.enter();
805 }
806
807 // at this point everyone should have synced up and not be doing any
808 // more work
809
810 if (barrier_aborted) {
811 // If the barrier aborted we ignore the overflow condition and
812 // just abort the whole marking phase as quickly as possible.
813 return;
814 }
815 }
816
817 void G1ConcurrentMark::enter_second_sync_barrier(uint worker_id) {
818 SuspendibleThreadSetLeaver sts_leave(concurrent());
819 _second_overflow_barrier_sync.enter();
820
821 // at this point everything should be re-initialized and ready to go
822 }
823
824 class G1CMConcurrentMarkingTask : public AbstractGangTask {
825 G1ConcurrentMark* _cm;
826 public:
827 void work(uint worker_id) {
828 assert(Thread::current()->is_ConcurrentGC_thread(), "Not a concurrent GC thread");
829 ResourceMark rm;
830
831 double start_vtime = os::elapsedVTime();
832
833 {
834 SuspendibleThreadSetJoiner sts_join;
835
836 assert(worker_id < _cm->active_tasks(), "invariant");
837
838 G1CMTask* task = _cm->task(worker_id);
839 task->record_start_time();
840 if (!_cm->has_aborted()) {
841 do {
842 task->do_marking_step(G1ConcMarkStepDurationMillis,
843 true /* do_termination */,
844 false /* is_serial*/);
845
846 _cm->do_yield_check();
847 } while (!_cm->has_aborted() && task->has_aborted());
848 }
849 task->record_end_time();
850 guarantee(!task->has_aborted() || _cm->has_aborted(), "invariant");
851 }
852
853 double end_vtime = os::elapsedVTime();
854 _cm->update_accum_task_vtime(worker_id, end_vtime - start_vtime);
855 }
856
857 G1CMConcurrentMarkingTask(G1ConcurrentMark* cm) :
858 AbstractGangTask("Concurrent Mark"), _cm(cm) { }
859
860 ~G1CMConcurrentMarkingTask() { }
861 };
862
863 uint G1ConcurrentMark::calc_active_marking_workers() {
864 uint result = 0;
865 if (!UseDynamicNumberOfGCThreads ||
866 (!FLAG_IS_DEFAULT(ConcGCThreads) &&
867 !ForceDynamicNumberOfGCThreads)) {
868 result = _max_concurrent_workers;
869 } else {
870 result =
871 AdaptiveSizePolicy::calc_default_active_workers(_max_concurrent_workers,
872 1, /* Minimum workers */
873 _num_concurrent_workers,
874 Threads::number_of_non_daemon_threads());
875 // Don't scale the result down by scale_concurrent_workers() because
876 // that scaling has already gone into "_max_concurrent_workers".
877 }
878 assert(result > 0 && result <= _max_concurrent_workers,
879 "Calculated number of marking workers must be larger than zero and at most the maximum %u, but is %u",
880 _max_concurrent_workers, result);
881 return result;
882 }
883
884 void G1ConcurrentMark::scan_root_region(HeapRegion* hr, uint worker_id) {
885 // Currently, only survivors can be root regions.
886 assert(hr->next_top_at_mark_start() == hr->bottom(), "invariant");
887 G1RootRegionScanClosure cl(_g1h, this, worker_id);
888
889 const uintx interval = PrefetchScanIntervalInBytes;
890 HeapWord* curr = hr->bottom();
891 const HeapWord* end = hr->top();
892 while (curr < end) {
893 Prefetch::read(curr, interval);
894 oop obj = oop(curr);
895 int size = obj->oop_iterate_size(&cl);
896 assert(size == obj->size(), "sanity");
897 curr += size;
898 }
899 }
900
901 class G1CMRootRegionScanTask : public AbstractGangTask {
902 G1ConcurrentMark* _cm;
903 public:
904 G1CMRootRegionScanTask(G1ConcurrentMark* cm) :
905 AbstractGangTask("G1 Root Region Scan"), _cm(cm) { }
906
907 void work(uint worker_id) {
908 assert(Thread::current()->is_ConcurrentGC_thread(),
909 "this should only be done by a conc GC thread");
910
911 G1CMRootRegions* root_regions = _cm->root_regions();
912 HeapRegion* hr = root_regions->claim_next();
913 while (hr != NULL) {
914 _cm->scan_root_region(hr, worker_id);
915 hr = root_regions->claim_next();
916 }
917 }
918 };
919
920 void G1ConcurrentMark::scan_root_regions() {
921 // scan_in_progress() will have been set to true only if there was
922 // at least one root region to scan. So, if it's false, we
923 // should not attempt to do any further work.
924 if (root_regions()->scan_in_progress()) {
925 assert(!has_aborted(), "Aborting before root region scanning is finished not supported.");
926
927 _num_concurrent_workers = MIN2(calc_active_marking_workers(),
928 // We distribute work on a per-region basis, so starting
929 // more threads than that is useless.
930 root_regions()->num_root_regions());
931 assert(_num_concurrent_workers <= _max_concurrent_workers,
932 "Maximum number of marking threads exceeded");
933
934 G1CMRootRegionScanTask task(this);
935 log_debug(gc, ergo)("Running %s using %u workers for %u work units.",
936 task.name(), _num_concurrent_workers, root_regions()->num_root_regions());
937 _concurrent_workers->run_task(&task, _num_concurrent_workers);
938
939 // It's possible that has_aborted() is true here without actually
940 // aborting the survivor scan earlier. This is OK as it's
941 // mainly used for sanity checking.
942 root_regions()->scan_finished();
943 }
944 }
945
946 void G1ConcurrentMark::concurrent_cycle_start() {
947 _gc_timer_cm->register_gc_start();
948
949 _gc_tracer_cm->report_gc_start(GCCause::_no_gc /* first parameter is not used */, _gc_timer_cm->gc_start());
950
951 _g1h->trace_heap_before_gc(_gc_tracer_cm);
952 }
953
954 void G1ConcurrentMark::concurrent_cycle_end() {
955 _g1h->collector_state()->set_clearing_next_bitmap(false);
956
957 _g1h->trace_heap_after_gc(_gc_tracer_cm);
958
959 if (has_aborted()) {
960 log_info(gc, marking)("Concurrent Mark Abort");
961 _gc_tracer_cm->report_concurrent_mode_failure();
962 }
963
964 _gc_timer_cm->register_gc_end();
965
966 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
967 }
968
969 void G1ConcurrentMark::mark_from_roots() {
970 _restart_for_overflow = false;
971
972 _num_concurrent_workers = calc_active_marking_workers();
973
974 uint active_workers = MAX2(1U, _num_concurrent_workers);
975
976 // Setting active workers is not guaranteed since fewer
977 // worker threads may currently exist and more may not be
978 // available.
979 active_workers = _concurrent_workers->update_active_workers(active_workers);
980 log_info(gc, task)("Using %u workers of %u for marking", active_workers, _concurrent_workers->total_workers());
981
982 // Parallel task terminator is set in "set_concurrency_and_phase()"
983 set_concurrency_and_phase(active_workers, true /* concurrent */);
984
985 G1CMConcurrentMarkingTask marking_task(this);
986 _concurrent_workers->run_task(&marking_task);
987 print_stats();
988 }
989
990 void G1ConcurrentMark::verify_during_pause(G1HeapVerifier::G1VerifyType type, VerifyOption vo, const char* caller) {
991 G1HeapVerifier* verifier = _g1h->verifier();
992
993 verifier->verify_region_sets_optional();
994
995 if (VerifyDuringGC) {
996 GCTraceTime(Debug, gc, phases) trace(caller, _gc_timer_cm);
997
998 size_t const BufLen = 512;
999 char buffer[BufLen];
1000
1001 jio_snprintf(buffer, BufLen, "During GC (%s)", caller);
1002 verifier->verify(type, vo, buffer);
1003 }
1004
1005 verifier->check_bitmaps(caller);
1006 }
1007
1008 class G1UpdateRemSetTrackingBeforeRebuild : public HeapRegionClosure {
1009 G1CollectedHeap* _g1h;
1010 G1ConcurrentMark* _cm;
1011
1012 uint _num_regions_selected_for_rebuild; // The number of regions actually selected for rebuild.
1013
1014 void update_remset_before_rebuild(HeapRegion * hr) {
1015 G1RemSetTrackingPolicy* tracking_policy = _g1h->g1_policy()->remset_tracker();
1016
1017 size_t live_bytes = _cm->liveness(hr->hrm_index()) * HeapWordSize;
1018 bool selected_for_rebuild = tracking_policy->update_before_rebuild(hr, live_bytes);
1019 if (selected_for_rebuild) {
1020 _num_regions_selected_for_rebuild++;
1021 }
1022 _cm->update_top_at_rebuild_start(hr);
1023 }
1024
1025 public:
1026 G1UpdateRemSetTrackingBeforeRebuild(G1CollectedHeap* g1h, G1ConcurrentMark* cm) :
1027 _g1h(g1h), _cm(cm), _num_regions_selected_for_rebuild(0) { }
1028
1029 virtual bool do_heap_region(HeapRegion* r) {
1030 update_remset_before_rebuild(r);
1031 return false;
1032 }
1033
1034 uint num_selected_for_rebuild() const { return _num_regions_selected_for_rebuild; }
1035 };
1036
1037 class G1UpdateRemSetTrackingAfterRebuild : public HeapRegionClosure {
1038 G1CollectedHeap* _g1h;
1039 public:
1040 G1UpdateRemSetTrackingAfterRebuild(G1CollectedHeap* g1h) : _g1h(g1h) { }
1041
1042 virtual bool do_heap_region(HeapRegion* r) {
1043 _g1h->g1_policy()->remset_tracker()->update_after_rebuild(r);
1044 return false;
1045 }
1046 };
1047
1048 void G1ConcurrentMark::remark() {
1049 assert_at_safepoint_on_vm_thread();
1050
1051 // If a full collection has happened, we should not continue. However we might
1052 // have ended up here as the Remark VM operation has been scheduled already.
1053 if (has_aborted()) {
1054 return;
1055 }
1056
1057 G1Policy* g1p = _g1h->g1_policy();
1058 g1p->record_concurrent_mark_remark_start();
1059
1060 double start = os::elapsedTime();
1061
1062 verify_during_pause(G1HeapVerifier::G1VerifyRemark, VerifyOption_G1UsePrevMarking, "Remark before");
1063
1064 {
1065 GCTraceTime(Debug, gc, phases) trace("Finalize Marking", _gc_timer_cm);
1066 finalize_marking();
1067 }
1068
1069 double mark_work_end = os::elapsedTime();
1070
1071 bool const mark_finished = !has_overflown();
1072 if (mark_finished) {
1073 weak_refs_work(false /* clear_all_soft_refs */);
1074
1075 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
1076 // We're done with marking.
1077 // This is the end of the marking cycle, we're expected all
1078 // threads to have SATB queues with active set to true.
1079 satb_mq_set.set_active_all_threads(false, /* new active value */
1080 true /* expected_active */);
1081
1082 {
1083 GCTraceTime(Debug, gc, phases)("Flush Task Caches");
1084 flush_all_task_caches();
1085 }
1086
1087 {
1088 GCTraceTime(Debug, gc, phases)("Update Remembered Set Tracking Before Rebuild");
1089 G1UpdateRemSetTrackingBeforeRebuild cl(_g1h, this);
1090 _g1h->heap_region_iterate(&cl);
1091 log_debug(gc, remset, tracking)("Remembered Set Tracking update regions total %u, selected %u",
1092 _g1h->num_regions(), cl.num_selected_for_rebuild());
1093 }
1094
1095 verify_during_pause(G1HeapVerifier::G1VerifyRemark, VerifyOption_G1UseNextMarking, "Remark after");
1096
1097 assert(!restart_for_overflow(), "sanity");
1098 // Completely reset the marking state since marking completed
1099 reset_at_marking_complete();
1100 } else {
1101 // We overflowed. Restart concurrent marking.
1102 _restart_for_overflow = true;
1103
1104 verify_during_pause(G1HeapVerifier::G1VerifyRemark, VerifyOption_G1UsePrevMarking, "Remark overflow");
1105
1106 // Clear the marking state because we will be restarting
1107 // marking due to overflowing the global mark stack.
1108 reset_marking_for_restart();
1109 }
1110
1111 {
1112 GCTraceTime(Debug, gc, phases)("Report Object Count");
1113 report_object_count();
1114 }
1115
1116 // Statistics
1117 double now = os::elapsedTime();
1118 _remark_mark_times.add((mark_work_end - start) * 1000.0);
1119 _remark_weak_ref_times.add((now - mark_work_end) * 1000.0);
1120 _remark_times.add((now - start) * 1000.0);
1121
1122 g1p->record_concurrent_mark_remark_end();
1123 }
1124
1125 class G1CleanupTask : public AbstractGangTask {
1126 // Per-region work during the Cleanup pause.
1127 class G1CleanupRegionsClosure : public HeapRegionClosure {
1128 G1CollectedHeap* _g1h;
1129 size_t _freed_bytes;
1130 FreeRegionList* _local_cleanup_list;
1131 uint _old_regions_removed;
1132 uint _humongous_regions_removed;
1133 HRRSCleanupTask* _hrrs_cleanup_task;
1134
1135 public:
1136 G1CleanupRegionsClosure(G1CollectedHeap* g1,
1137 FreeRegionList* local_cleanup_list,
1138 HRRSCleanupTask* hrrs_cleanup_task) :
1139 _g1h(g1),
1140 _freed_bytes(0),
1141 _local_cleanup_list(local_cleanup_list),
1142 _old_regions_removed(0),
1143 _humongous_regions_removed(0),
1144 _hrrs_cleanup_task(hrrs_cleanup_task) { }
1145
1146 size_t freed_bytes() { return _freed_bytes; }
1147 const uint old_regions_removed() { return _old_regions_removed; }
1148 const uint humongous_regions_removed() { return _humongous_regions_removed; }
1149
1150 bool do_heap_region(HeapRegion *hr) {
1151 hr->note_end_of_marking();
1152
1153 if (hr->used() > 0 && hr->max_live_bytes() == 0 && !hr->is_young() && !hr->is_archive()) {
1154 _freed_bytes += hr->used();
1155 hr->set_containing_set(NULL);
1156 if (hr->is_humongous()) {
1157 _humongous_regions_removed++;
1158 _g1h->free_humongous_region(hr, _local_cleanup_list);
1159 } else {
1160 _old_regions_removed++;
1161 _g1h->free_region(hr, _local_cleanup_list, false /* skip_remset */, false /* skip_hcc */, true /* locked */);
1162 }
1163 hr->clear_cardtable();
1164 _g1h->concurrent_mark()->clear_statistics_in_region(hr->hrm_index());
1165 log_trace(gc)("Reclaimed empty region %u (%s) bot " PTR_FORMAT, hr->hrm_index(), hr->get_short_type_str(), p2i(hr->bottom()));
1166 } else {
1167 hr->rem_set()->do_cleanup_work(_hrrs_cleanup_task);
1168 }
1169
1170 return false;
1171 }
1172 };
1173
1174 G1CollectedHeap* _g1h;
1175 FreeRegionList* _cleanup_list;
1176 HeapRegionClaimer _hrclaimer;
1177
1178 public:
1179 G1CleanupTask(G1CollectedHeap* g1h, FreeRegionList* cleanup_list, uint n_workers) :
1180 AbstractGangTask("G1 Cleanup"),
1181 _g1h(g1h),
1182 _cleanup_list(cleanup_list),
1183 _hrclaimer(n_workers) {
1184
1185 HeapRegionRemSet::reset_for_cleanup_tasks();
1186 }
1187
1188 void work(uint worker_id) {
1189 FreeRegionList local_cleanup_list("Local Cleanup List");
1190 HRRSCleanupTask hrrs_cleanup_task;
1191 G1CleanupRegionsClosure cl(_g1h,
1192 &local_cleanup_list,
1193 &hrrs_cleanup_task);
1194 _g1h->heap_region_par_iterate_from_worker_offset(&cl, &_hrclaimer, worker_id);
1195 assert(cl.is_complete(), "Shouldn't have aborted!");
1196
1197 // Now update the old/humongous region sets
1198 _g1h->remove_from_old_sets(cl.old_regions_removed(), cl.humongous_regions_removed());
1199 {
1200 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
1201 _g1h->decrement_summary_bytes(cl.freed_bytes());
1202
1203 _cleanup_list->add_ordered(&local_cleanup_list);
1204 assert(local_cleanup_list.is_empty(), "post-condition");
1205
1206 HeapRegionRemSet::finish_cleanup_task(&hrrs_cleanup_task);
1207 }
1208 }
1209 };
1210
1211 void G1ConcurrentMark::reclaim_empty_regions() {
1212 WorkGang* workers = _g1h->workers();
1213 FreeRegionList empty_regions_list("Empty Regions After Mark List");
1214
1215 G1CleanupTask cl(_g1h, &empty_regions_list, workers->active_workers());
1216 workers->run_task(&cl);
1217
1218 if (!empty_regions_list.is_empty()) {
1219 log_debug(gc)("Reclaimed %u empty regions", empty_regions_list.length());
1220 // Now print the empty regions list.
1221 G1HRPrinter* hrp = _g1h->hr_printer();
1222 if (hrp->is_active()) {
1223 FreeRegionListIterator iter(&empty_regions_list);
1224 while (iter.more_available()) {
1225 HeapRegion* hr = iter.get_next();
1226 hrp->cleanup(hr);
1227 }
1228 }
1229 // And actually make them available.
1230 _g1h->prepend_to_freelist(&empty_regions_list);
1231 }
1232 }
1233
1234 void G1ConcurrentMark::cleanup() {
1235 assert_at_safepoint_on_vm_thread();
1236
1237 // If a full collection has happened, we shouldn't do this.
1238 if (has_aborted()) {
1239 return;
1240 }
1241
1242 G1Policy* g1p = _g1h->g1_policy();
1243 g1p->record_concurrent_mark_cleanup_start();
1244
1245 double start = os::elapsedTime();
1246
1247 verify_during_pause(G1HeapVerifier::G1VerifyCleanup, VerifyOption_G1UseNextMarking, "Cleanup before");
1248
1249 {
1250 GCTraceTime(Debug, gc, phases)("Update Remembered Set Tracking After Rebuild");
1251 G1UpdateRemSetTrackingAfterRebuild cl(_g1h);
1252 _g1h->heap_region_iterate(&cl);
1253 }
1254
1255 if (log_is_enabled(Trace, gc, liveness)) {
1256 G1PrintRegionLivenessInfoClosure cl("Post-Cleanup");
1257 _g1h->heap_region_iterate(&cl);
1258 }
1259
1260 // Install newly created mark bitmap as "prev".
1261 swap_mark_bitmaps();
1262 {
1263 GCTraceTime(Debug, gc, phases)("Reclaim Empty Regions");
1264 reclaim_empty_regions();
1265 }
1266
1267 // Cleanup will have freed any regions completely full of garbage.
1268 // Update the soft reference policy with the new heap occupancy.
1269 Universe::update_heap_info_at_gc();
1270
1271 // Clean out dead classes and update Metaspace sizes.
1272 if (ClassUnloadingWithConcurrentMark) {
1273 GCTraceTime(Debug, gc, phases)("Purge Metaspace");
1274 ClassLoaderDataGraph::purge();
1275 }
1276 MetaspaceGC::compute_new_size();
1277
1278 // We reclaimed old regions so we should calculate the sizes to make
1279 // sure we update the old gen/space data.
1280 _g1h->g1mm()->update_sizes();
1281
1282 verify_during_pause(G1HeapVerifier::G1VerifyCleanup, VerifyOption_G1UsePrevMarking, "Cleanup after");
1283
1284 // We need to make this be a "collection" so any collection pause that
1285 // races with it goes around and waits for Cleanup to finish.
1286 _g1h->increment_total_collections();
1287
1288 // Local statistics
1289 double recent_cleanup_time = (os::elapsedTime() - start);
1290 _total_cleanup_time += recent_cleanup_time;
1291 _cleanup_times.add(recent_cleanup_time);
1292
1293 {
1294 GCTraceTime(Debug, gc, phases)("Finalize Concurrent Mark Cleanup");
1295 _g1h->g1_policy()->record_concurrent_mark_cleanup_end();
1296 }
1297 }
1298
1299 // Supporting Object and Oop closures for reference discovery
1300 // and processing in during marking
1301
1302 bool G1CMIsAliveClosure::do_object_b(oop obj) {
1303 HeapWord* addr = (HeapWord*)obj;
1304 return addr != NULL &&
1305 (!_g1h->is_in_g1_reserved(addr) || !_g1h->is_obj_ill(obj));
1306 }
1307
1308 // 'Keep Alive' oop closure used by both serial parallel reference processing.
1309 // Uses the G1CMTask associated with a worker thread (for serial reference
1310 // processing the G1CMTask for worker 0 is used) to preserve (mark) and
1311 // trace referent objects.
1312 //
1313 // Using the G1CMTask and embedded local queues avoids having the worker
1314 // threads operating on the global mark stack. This reduces the risk
1315 // of overflowing the stack - which we would rather avoid at this late
1316 // state. Also using the tasks' local queues removes the potential
1317 // of the workers interfering with each other that could occur if
1318 // operating on the global stack.
1319
1320 class G1CMKeepAliveAndDrainClosure : public OopClosure {
1321 G1ConcurrentMark* _cm;
1322 G1CMTask* _task;
1323 int _ref_counter_limit;
1324 int _ref_counter;
1325 bool _is_serial;
1326 public:
1327 G1CMKeepAliveAndDrainClosure(G1ConcurrentMark* cm, G1CMTask* task, bool is_serial) :
1328 _cm(cm), _task(task), _is_serial(is_serial),
1329 _ref_counter_limit(G1RefProcDrainInterval) {
1330 assert(_ref_counter_limit > 0, "sanity");
1331 assert(!_is_serial || _task->worker_id() == 0, "only task 0 for serial code");
1332 _ref_counter = _ref_counter_limit;
1333 }
1334
1335 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
1336 virtual void do_oop( oop* p) { do_oop_work(p); }
1337
1338 template <class T> void do_oop_work(T* p) {
1339 if (!_cm->has_overflown()) {
1340 _task->deal_with_reference(p);
1341 _ref_counter--;
1342
1343 if (_ref_counter == 0) {
1344 // We have dealt with _ref_counter_limit references, pushing them
1345 // and objects reachable from them on to the local stack (and
1346 // possibly the global stack). Call G1CMTask::do_marking_step() to
1347 // process these entries.
1348 //
1349 // We call G1CMTask::do_marking_step() in a loop, which we'll exit if
1350 // there's nothing more to do (i.e. we're done with the entries that
1351 // were pushed as a result of the G1CMTask::deal_with_reference() calls
1352 // above) or we overflow.
1353 //
1354 // Note: G1CMTask::do_marking_step() can set the G1CMTask::has_aborted()
1355 // flag while there may still be some work to do. (See the comment at
1356 // the beginning of G1CMTask::do_marking_step() for those conditions -
1357 // one of which is reaching the specified time target.) It is only
1358 // when G1CMTask::do_marking_step() returns without setting the
1359 // has_aborted() flag that the marking step has completed.
1360 do {
1361 double mark_step_duration_ms = G1ConcMarkStepDurationMillis;
1362 _task->do_marking_step(mark_step_duration_ms,
1363 false /* do_termination */,
1364 _is_serial);
1365 } while (_task->has_aborted() && !_cm->has_overflown());
1366 _ref_counter = _ref_counter_limit;
1367 }
1368 }
1369 }
1370 };
1371
1372 // 'Drain' oop closure used by both serial and parallel reference processing.
1373 // Uses the G1CMTask associated with a given worker thread (for serial
1374 // reference processing the G1CMtask for worker 0 is used). Calls the
1375 // do_marking_step routine, with an unbelievably large timeout value,
1376 // to drain the marking data structures of the remaining entries
1377 // added by the 'keep alive' oop closure above.
1378
1379 class G1CMDrainMarkingStackClosure : public VoidClosure {
1380 G1ConcurrentMark* _cm;
1381 G1CMTask* _task;
1382 bool _is_serial;
1383 public:
1384 G1CMDrainMarkingStackClosure(G1ConcurrentMark* cm, G1CMTask* task, bool is_serial) :
1385 _cm(cm), _task(task), _is_serial(is_serial) {
1386 assert(!_is_serial || _task->worker_id() == 0, "only task 0 for serial code");
1387 }
1388
1389 void do_void() {
1390 do {
1391 // We call G1CMTask::do_marking_step() to completely drain the local
1392 // and global marking stacks of entries pushed by the 'keep alive'
1393 // oop closure (an instance of G1CMKeepAliveAndDrainClosure above).
1394 //
1395 // G1CMTask::do_marking_step() is called in a loop, which we'll exit
1396 // if there's nothing more to do (i.e. we've completely drained the
1397 // entries that were pushed as a a result of applying the 'keep alive'
1398 // closure to the entries on the discovered ref lists) or we overflow
1399 // the global marking stack.
1400 //
1401 // Note: G1CMTask::do_marking_step() can set the G1CMTask::has_aborted()
1402 // flag while there may still be some work to do. (See the comment at
1403 // the beginning of G1CMTask::do_marking_step() for those conditions -
1404 // one of which is reaching the specified time target.) It is only
1405 // when G1CMTask::do_marking_step() returns without setting the
1406 // has_aborted() flag that the marking step has completed.
1407
1408 _task->do_marking_step(1000000000.0 /* something very large */,
1409 true /* do_termination */,
1410 _is_serial);
1411 } while (_task->has_aborted() && !_cm->has_overflown());
1412 }
1413 };
1414
1415 // Implementation of AbstractRefProcTaskExecutor for parallel
1416 // reference processing at the end of G1 concurrent marking
1417
1418 class G1CMRefProcTaskExecutor : public AbstractRefProcTaskExecutor {
1419 private:
1420 G1CollectedHeap* _g1h;
1421 G1ConcurrentMark* _cm;
1422 WorkGang* _workers;
1423 uint _active_workers;
1424
1425 public:
1426 G1CMRefProcTaskExecutor(G1CollectedHeap* g1h,
1427 G1ConcurrentMark* cm,
1428 WorkGang* workers,
1429 uint n_workers) :
1430 _g1h(g1h), _cm(cm),
1431 _workers(workers), _active_workers(n_workers) { }
1432
1433 // Executes the given task using concurrent marking worker threads.
1434 virtual void execute(ProcessTask& task);
1435 virtual void execute(EnqueueTask& task);
1436 };
1437
1438 class G1CMRefProcTaskProxy : public AbstractGangTask {
1439 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
1440 ProcessTask& _proc_task;
1441 G1CollectedHeap* _g1h;
1442 G1ConcurrentMark* _cm;
1443
1444 public:
1445 G1CMRefProcTaskProxy(ProcessTask& proc_task,
1446 G1CollectedHeap* g1h,
1447 G1ConcurrentMark* cm) :
1448 AbstractGangTask("Process reference objects in parallel"),
1449 _proc_task(proc_task), _g1h(g1h), _cm(cm) {
1450 ReferenceProcessor* rp = _g1h->ref_processor_cm();
1451 assert(rp->processing_is_mt(), "shouldn't be here otherwise");
1452 }
1453
1454 virtual void work(uint worker_id) {
1455 ResourceMark rm;
1456 HandleMark hm;
1457 G1CMTask* task = _cm->task(worker_id);
1458 G1CMIsAliveClosure g1_is_alive(_g1h);
1459 G1CMKeepAliveAndDrainClosure g1_par_keep_alive(_cm, task, false /* is_serial */);
1460 G1CMDrainMarkingStackClosure g1_par_drain(_cm, task, false /* is_serial */);
1461
1462 _proc_task.work(worker_id, g1_is_alive, g1_par_keep_alive, g1_par_drain);
1463 }
1464 };
1465
1466 void G1CMRefProcTaskExecutor::execute(ProcessTask& proc_task) {
1467 assert(_workers != NULL, "Need parallel worker threads.");
1468 assert(_g1h->ref_processor_cm()->processing_is_mt(), "processing is not MT");
1469
1470 G1CMRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _cm);
1471
1472 // We need to reset the concurrency level before each
1473 // proxy task execution, so that the termination protocol
1474 // and overflow handling in G1CMTask::do_marking_step() knows
1475 // how many workers to wait for.
1476 _cm->set_concurrency(_active_workers);
1477 _workers->run_task(&proc_task_proxy);
1478 }
1479
1480 class G1CMRefEnqueueTaskProxy : public AbstractGangTask {
1481 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
1482 EnqueueTask& _enq_task;
1483
1484 public:
1485 G1CMRefEnqueueTaskProxy(EnqueueTask& enq_task) :
1486 AbstractGangTask("Enqueue reference objects in parallel"),
1487 _enq_task(enq_task) { }
1488
1489 virtual void work(uint worker_id) {
1490 _enq_task.work(worker_id);
1491 }
1492 };
1493
1494 void G1CMRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
1495 assert(_workers != NULL, "Need parallel worker threads.");
1496 assert(_g1h->ref_processor_cm()->processing_is_mt(), "processing is not MT");
1497
1498 G1CMRefEnqueueTaskProxy enq_task_proxy(enq_task);
1499
1500 // Not strictly necessary but...
1501 //
1502 // We need to reset the concurrency level before each
1503 // proxy task execution, so that the termination protocol
1504 // and overflow handling in G1CMTask::do_marking_step() knows
1505 // how many workers to wait for.
1506 _cm->set_concurrency(_active_workers);
1507 _workers->run_task(&enq_task_proxy);
1508 }
1509
1510 void G1ConcurrentMark::weak_refs_work(bool clear_all_soft_refs) {
1511 ResourceMark rm;
1512 HandleMark hm;
1513
1514 // Is alive closure.
1515 G1CMIsAliveClosure g1_is_alive(_g1h);
1516
1517 // Inner scope to exclude the cleaning of the string and symbol
1518 // tables from the displayed time.
1519 {
1520 GCTraceTime(Debug, gc, phases) trace("Reference Processing", _gc_timer_cm);
1521
1522 ReferenceProcessor* rp = _g1h->ref_processor_cm();
1523
1524 // See the comment in G1CollectedHeap::ref_processing_init()
1525 // about how reference processing currently works in G1.
1526
1527 // Set the soft reference policy
1528 rp->setup_policy(clear_all_soft_refs);
1529 assert(_global_mark_stack.is_empty(), "mark stack should be empty");
1530
1531 // Instances of the 'Keep Alive' and 'Complete GC' closures used
1532 // in serial reference processing. Note these closures are also
1533 // used for serially processing (by the the current thread) the
1534 // JNI references during parallel reference processing.
1535 //
1536 // These closures do not need to synchronize with the worker
1537 // threads involved in parallel reference processing as these
1538 // instances are executed serially by the current thread (e.g.
1539 // reference processing is not multi-threaded and is thus
1540 // performed by the current thread instead of a gang worker).
1541 //
1542 // The gang tasks involved in parallel reference processing create
1543 // their own instances of these closures, which do their own
1544 // synchronization among themselves.
1545 G1CMKeepAliveAndDrainClosure g1_keep_alive(this, task(0), true /* is_serial */);
1546 G1CMDrainMarkingStackClosure g1_drain_mark_stack(this, task(0), true /* is_serial */);
1547
1548 // We need at least one active thread. If reference processing
1549 // is not multi-threaded we use the current (VMThread) thread,
1550 // otherwise we use the work gang from the G1CollectedHeap and
1551 // we utilize all the worker threads we can.
1552 bool processing_is_mt = rp->processing_is_mt();
1553 uint active_workers = (processing_is_mt ? _g1h->workers()->active_workers() : 1U);
1554 active_workers = MAX2(MIN2(active_workers, _max_num_tasks), 1U);
1555
1556 // Parallel processing task executor.
1557 G1CMRefProcTaskExecutor par_task_executor(_g1h, this,
1558 _g1h->workers(), active_workers);
1559 AbstractRefProcTaskExecutor* executor = (processing_is_mt ? &par_task_executor : NULL);
1560
1561 // Set the concurrency level. The phase was already set prior to
1562 // executing the remark task.
1563 set_concurrency(active_workers);
1564
1565 // Set the degree of MT processing here. If the discovery was done MT,
1566 // the number of threads involved during discovery could differ from
1567 // the number of active workers. This is OK as long as the discovered
1568 // Reference lists are balanced (see balance_all_queues() and balance_queues()).
1569 rp->set_active_mt_degree(active_workers);
1570
1571 ReferenceProcessorPhaseTimes pt(_gc_timer_cm, rp->num_q());
1572
1573 // Process the weak references.
1574 const ReferenceProcessorStats& stats =
1575 rp->process_discovered_references(&g1_is_alive,
1576 &g1_keep_alive,
1577 &g1_drain_mark_stack,
1578 executor,
1579 &pt);
1580 _gc_tracer_cm->report_gc_reference_stats(stats);
1581 pt.print_all_references();
1582
1583 // The do_oop work routines of the keep_alive and drain_marking_stack
1584 // oop closures will set the has_overflown flag if we overflow the
1585 // global marking stack.
1586
1587 assert(has_overflown() || _global_mark_stack.is_empty(),
1588 "Mark stack should be empty (unless it has overflown)");
1589
1590 assert(rp->num_q() == active_workers, "why not");
1591
1592 rp->enqueue_discovered_references(executor, &pt);
1593
1594 rp->verify_no_references_recorded();
1595
1596 pt.print_enqueue_phase();
1597
1598 assert(!rp->discovery_enabled(), "Post condition");
1599 }
1600
1601 assert(has_overflown() || _global_mark_stack.is_empty(),
1602 "Mark stack should be empty (unless it has overflown)");
1603
1604 {
1605 GCTraceTime(Debug, gc, phases) debug("Weak Processing", _gc_timer_cm);
1606 WeakProcessor::weak_oops_do(&g1_is_alive, &do_nothing_cl);
1607 }
1608
1609 if (has_overflown()) {
1610 // We can not trust g1_is_alive if the marking stack overflowed
1611 return;
1612 }
1613
1614 assert(_global_mark_stack.is_empty(), "Marking should have completed");
1615
1616 // Unload Klasses, String, Symbols, Code Cache, etc.
1617 if (ClassUnloadingWithConcurrentMark) {
1618 GCTraceTime(Debug, gc, phases) debug("Class Unloading", _gc_timer_cm);
1619 bool purged_classes = SystemDictionary::do_unloading(&g1_is_alive, _gc_timer_cm, false /* Defer cleaning */);
1620 _g1h->complete_cleaning(&g1_is_alive, purged_classes);
1621 } else {
1622 GCTraceTime(Debug, gc, phases) debug("Cleanup", _gc_timer_cm);
1623 // No need to clean string table and symbol table as they are treated as strong roots when
1624 // class unloading is disabled.
1625 _g1h->partial_cleaning(&g1_is_alive, false, false, G1StringDedup::is_enabled());
1626 }
1627 }
1628
1629 void G1ConcurrentMark::report_object_count() {
1630 G1CMIsAliveClosure is_alive(_g1h);
1631 _gc_tracer_cm->report_object_count_after_gc(&is_alive);
1632 }
1633
1634 void G1ConcurrentMark::swap_mark_bitmaps() {
1635 G1CMBitMap* temp = _prev_mark_bitmap;
1636 _prev_mark_bitmap = _next_mark_bitmap;
1637 _next_mark_bitmap = temp;
1638 _g1h->collector_state()->set_clearing_next_bitmap(true);
1639 }
1640
1641 // Closure for marking entries in SATB buffers.
1642 class G1CMSATBBufferClosure : public SATBBufferClosure {
1643 private:
1644 G1CMTask* _task;
1645 G1CollectedHeap* _g1h;
1646
1647 // This is very similar to G1CMTask::deal_with_reference, but with
1648 // more relaxed requirements for the argument, so this must be more
1649 // circumspect about treating the argument as an object.
1650 void do_entry(void* entry) const {
1651 _task->increment_refs_reached();
1652 oop const obj = static_cast<oop>(entry);
1653 _task->make_reference_grey(obj);
1654 }
1655
1656 public:
1657 G1CMSATBBufferClosure(G1CMTask* task, G1CollectedHeap* g1h)
1658 : _task(task), _g1h(g1h) { }
1659
1660 virtual void do_buffer(void** buffer, size_t size) {
1661 for (size_t i = 0; i < size; ++i) {
1662 do_entry(buffer[i]);
1663 }
1664 }
1665 };
1666
1667 class G1RemarkThreadsClosure : public ThreadClosure {
1668 G1CMSATBBufferClosure _cm_satb_cl;
1669 G1CMOopClosure _cm_cl;
1670 MarkingCodeBlobClosure _code_cl;
1671 int _thread_parity;
1672
1673 public:
1674 G1RemarkThreadsClosure(G1CollectedHeap* g1h, G1CMTask* task) :
1675 _cm_satb_cl(task, g1h),
1676 _cm_cl(g1h, task),
1677 _code_cl(&_cm_cl, !CodeBlobToOopClosure::FixRelocations),
1678 _thread_parity(Threads::thread_claim_parity()) {}
1679
1680 void do_thread(Thread* thread) {
1681 if (thread->is_Java_thread()) {
1682 if (thread->claim_oops_do(true, _thread_parity)) {
1683 JavaThread* jt = (JavaThread*)thread;
1684
1685 // In theory it should not be neccessary to explicitly walk the nmethods to find roots for concurrent marking
1686 // however the liveness of oops reachable from nmethods have very complex lifecycles:
1687 // * Alive if on the stack of an executing method
1688 // * Weakly reachable otherwise
1689 // Some objects reachable from nmethods, such as the class loader (or klass_holder) of the receiver should be
1690 // live by the SATB invariant but other oops recorded in nmethods may behave differently.
1691 jt->nmethods_do(&_code_cl);
1692
1693 jt->satb_mark_queue().apply_closure_and_empty(&_cm_satb_cl);
1694 }
1695 } else if (thread->is_VM_thread()) {
1696 if (thread->claim_oops_do(true, _thread_parity)) {
1697 JavaThread::satb_mark_queue_set().shared_satb_queue()->apply_closure_and_empty(&_cm_satb_cl);
1698 }
1699 }
1700 }
1701 };
1702
1703 class G1CMRemarkTask : public AbstractGangTask {
1704 G1ConcurrentMark* _cm;
1705 public:
1706 void work(uint worker_id) {
1707 G1CMTask* task = _cm->task(worker_id);
1708 task->record_start_time();
1709 {
1710 ResourceMark rm;
1711 HandleMark hm;
1712
1713 G1RemarkThreadsClosure threads_f(G1CollectedHeap::heap(), task);
1714 Threads::threads_do(&threads_f);
1715 }
1716
1717 do {
1718 task->do_marking_step(1000000000.0 /* something very large */,
1719 true /* do_termination */,
1720 false /* is_serial */);
1721 } while (task->has_aborted() && !_cm->has_overflown());
1722 // If we overflow, then we do not want to restart. We instead
1723 // want to abort remark and do concurrent marking again.
1724 task->record_end_time();
1725 }
1726
1727 G1CMRemarkTask(G1ConcurrentMark* cm, uint active_workers) :
1728 AbstractGangTask("Par Remark"), _cm(cm) {
1729 _cm->terminator()->reset_for_reuse(active_workers);
1730 }
1731 };
1732
1733 void G1ConcurrentMark::finalize_marking() {
1734 ResourceMark rm;
1735 HandleMark hm;
1736
1737 _g1h->ensure_parsability(false);
1738
1739 // this is remark, so we'll use up all active threads
1740 uint active_workers = _g1h->workers()->active_workers();
1741 set_concurrency_and_phase(active_workers, false /* concurrent */);
1742 // Leave _parallel_marking_threads at it's
1743 // value originally calculated in the G1ConcurrentMark
1744 // constructor and pass values of the active workers
1745 // through the gang in the task.
1746
1747 {
1748 StrongRootsScope srs(active_workers);
1749
1750 G1CMRemarkTask remarkTask(this, active_workers);
1751 // We will start all available threads, even if we decide that the
1752 // active_workers will be fewer. The extra ones will just bail out
1753 // immediately.
1754 _g1h->workers()->run_task(&remarkTask);
1755 }
1756
1757 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
1758 guarantee(has_overflown() ||
1759 satb_mq_set.completed_buffers_num() == 0,
1760 "Invariant: has_overflown = %s, num buffers = " SIZE_FORMAT,
1761 BOOL_TO_STR(has_overflown()),
1762 satb_mq_set.completed_buffers_num());
1763
1764 print_stats();
1765 }
1766
1767 void G1ConcurrentMark::flush_all_task_caches() {
1768 size_t hits = 0;
1769 size_t misses = 0;
1770 for (uint i = 0; i < _max_num_tasks; i++) {
1771 Pair<size_t, size_t> stats = _tasks[i]->flush_mark_stats_cache();
1772 hits += stats.first;
1773 misses += stats.second;
1774 }
1775 size_t sum = hits + misses;
1776 log_debug(gc, stats)("Mark stats cache hits " SIZE_FORMAT " misses " SIZE_FORMAT " ratio %1.3lf",
1777 hits, misses, percent_of(hits, sum));
1778 }
1779
1780 void G1ConcurrentMark::clear_range_in_prev_bitmap(MemRegion mr) {
1781 _prev_mark_bitmap->clear_range(mr);
1782 }
1783
1784 HeapRegion*
1785 G1ConcurrentMark::claim_region(uint worker_id) {
1786 // "checkpoint" the finger
1787 HeapWord* finger = _finger;
1788
1789 while (finger < _heap.end()) {
1790 assert(_g1h->is_in_g1_reserved(finger), "invariant");
1791
1792 HeapRegion* curr_region = _g1h->heap_region_containing(finger);
1793 // Make sure that the reads below do not float before loading curr_region.
1794 OrderAccess::loadload();
1795 // Above heap_region_containing may return NULL as we always scan claim
1796 // until the end of the heap. In this case, just jump to the next region.
1797 HeapWord* end = curr_region != NULL ? curr_region->end() : finger + HeapRegion::GrainWords;
1798
1799 // Is the gap between reading the finger and doing the CAS too long?
1800 HeapWord* res = Atomic::cmpxchg(end, &_finger, finger);
1801 if (res == finger && curr_region != NULL) {
1802 // we succeeded
1803 HeapWord* bottom = curr_region->bottom();
1804 HeapWord* limit = curr_region->next_top_at_mark_start();
1805
1806 // notice that _finger == end cannot be guaranteed here since,
1807 // someone else might have moved the finger even further
1808 assert(_finger >= end, "the finger should have moved forward");
1809
1810 if (limit > bottom) {
1811 return curr_region;
1812 } else {
1813 assert(limit == bottom,
1814 "the region limit should be at bottom");
1815 // we return NULL and the caller should try calling
1816 // claim_region() again.
1817 return NULL;
1818 }
1819 } else {
1820 assert(_finger > finger, "the finger should have moved forward");
1821 // read it again
1822 finger = _finger;
1823 }
1824 }
1825
1826 return NULL;
1827 }
1828
1829 #ifndef PRODUCT
1830 class VerifyNoCSetOops {
1831 G1CollectedHeap* _g1h;
1832 const char* _phase;
1833 int _info;
1834
1835 public:
1836 VerifyNoCSetOops(const char* phase, int info = -1) :
1837 _g1h(G1CollectedHeap::heap()),
1838 _phase(phase),
1839 _info(info)
1840 { }
1841
1842 void operator()(G1TaskQueueEntry task_entry) const {
1843 if (task_entry.is_array_slice()) {
1844 guarantee(_g1h->is_in_reserved(task_entry.slice()), "Slice " PTR_FORMAT " must be in heap.", p2i(task_entry.slice()));
1845 return;
1846 }
1847 guarantee(oopDesc::is_oop(task_entry.obj()),
1848 "Non-oop " PTR_FORMAT ", phase: %s, info: %d",
1849 p2i(task_entry.obj()), _phase, _info);
1850 guarantee(!_g1h->is_in_cset(task_entry.obj()),
1851 "obj: " PTR_FORMAT " in CSet, phase: %s, info: %d",
1852 p2i(task_entry.obj()), _phase, _info);
1853 }
1854 };
1855
1856 void G1ConcurrentMark::verify_no_cset_oops() {
1857 assert(SafepointSynchronize::is_at_safepoint(), "should be at a safepoint");
1858 if (!_g1h->collector_state()->mark_or_rebuild_in_progress()) {
1859 return;
1860 }
1861
1862 // Verify entries on the global mark stack
1863 _global_mark_stack.iterate(VerifyNoCSetOops("Stack"));
1864
1865 // Verify entries on the task queues
1866 for (uint i = 0; i < _max_num_tasks; ++i) {
1867 G1CMTaskQueue* queue = _task_queues->queue(i);
1868 queue->iterate(VerifyNoCSetOops("Queue", i));
1869 }
1870
1871 // Verify the global finger
1872 HeapWord* global_finger = finger();
1873 if (global_finger != NULL && global_finger < _heap.end()) {
1874 // Since we always iterate over all regions, we might get a NULL HeapRegion
1875 // here.
1876 HeapRegion* global_hr = _g1h->heap_region_containing(global_finger);
1877 guarantee(global_hr == NULL || global_finger == global_hr->bottom(),
1878 "global finger: " PTR_FORMAT " region: " HR_FORMAT,
1879 p2i(global_finger), HR_FORMAT_PARAMS(global_hr));
1880 }
1881
1882 // Verify the task fingers
1883 assert(_num_concurrent_workers <= _max_num_tasks, "sanity");
1884 for (uint i = 0; i < _num_concurrent_workers; ++i) {
1885 G1CMTask* task = _tasks[i];
1886 HeapWord* task_finger = task->finger();
1887 if (task_finger != NULL && task_finger < _heap.end()) {
1888 // See above note on the global finger verification.
1889 HeapRegion* task_hr = _g1h->heap_region_containing(task_finger);
1890 guarantee(task_hr == NULL || task_finger == task_hr->bottom() ||
1891 !task_hr->in_collection_set(),
1892 "task finger: " PTR_FORMAT " region: " HR_FORMAT,
1893 p2i(task_finger), HR_FORMAT_PARAMS(task_hr));
1894 }
1895 }
1896 }
1897 #endif // PRODUCT
1898
1899 void G1ConcurrentMark::rebuild_rem_set_concurrently() {
1900 _g1h->g1_rem_set()->rebuild_rem_set(this, _concurrent_workers, _worker_id_offset);
1901 }
1902
1903 void G1ConcurrentMark::print_stats() {
1904 if (!log_is_enabled(Debug, gc, stats)) {
1905 return;
1906 }
1907 log_debug(gc, stats)("---------------------------------------------------------------------");
1908 for (size_t i = 0; i < _num_active_tasks; ++i) {
1909 _tasks[i]->print_stats();
1910 log_debug(gc, stats)("---------------------------------------------------------------------");
1911 }
1912 }
1913
1914 void G1ConcurrentMark::concurrent_cycle_abort() {
1915 if (!cm_thread()->during_cycle() || _has_aborted) {
1916 // We haven't started a concurrent cycle or we have already aborted it. No need to do anything.
1917 return;
1918 }
1919
1920 // Clear all marks in the next bitmap for the next marking cycle. This will allow us to skip the next
1921 // concurrent bitmap clearing.
1922 {
1923 GCTraceTime(Debug, gc)("Clear Next Bitmap");
1924 clear_bitmap(_next_mark_bitmap, _g1h->workers(), false);
1925 }
1926 // Note we cannot clear the previous marking bitmap here
1927 // since VerifyDuringGC verifies the objects marked during
1928 // a full GC against the previous bitmap.
1929
1930 // Empty mark stack
1931 reset_marking_for_restart();
1932 for (uint i = 0; i < _max_num_tasks; ++i) {
1933 _tasks[i]->clear_region_fields();
1934 }
1935 _first_overflow_barrier_sync.abort();
1936 _second_overflow_barrier_sync.abort();
1937 _has_aborted = true;
1938
1939 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
1940 satb_mq_set.abandon_partial_marking();
1941 // This can be called either during or outside marking, we'll read
1942 // the expected_active value from the SATB queue set.
1943 satb_mq_set.set_active_all_threads(
1944 false, /* new active value */
1945 satb_mq_set.is_active() /* expected_active */);
1946 }
1947
1948 static void print_ms_time_info(const char* prefix, const char* name,
1949 NumberSeq& ns) {
1950 log_trace(gc, marking)("%s%5d %12s: total time = %8.2f s (avg = %8.2f ms).",
1951 prefix, ns.num(), name, ns.sum()/1000.0, ns.avg());
1952 if (ns.num() > 0) {
1953 log_trace(gc, marking)("%s [std. dev = %8.2f ms, max = %8.2f ms]",
1954 prefix, ns.sd(), ns.maximum());
1955 }
1956 }
1957
1958 void G1ConcurrentMark::print_summary_info() {
1959 Log(gc, marking) log;
1960 if (!log.is_trace()) {
1961 return;
1962 }
1963
1964 log.trace(" Concurrent marking:");
1965 print_ms_time_info(" ", "init marks", _init_times);
1966 print_ms_time_info(" ", "remarks", _remark_times);
1967 {
1968 print_ms_time_info(" ", "final marks", _remark_mark_times);
1969 print_ms_time_info(" ", "weak refs", _remark_weak_ref_times);
1970
1971 }
1972 print_ms_time_info(" ", "cleanups", _cleanup_times);
1973 log.trace(" Finalize live data total time = %8.2f s (avg = %8.2f ms).",
1974 _total_cleanup_time, (_cleanup_times.num() > 0 ? _total_cleanup_time * 1000.0 / (double)_cleanup_times.num() : 0.0));
1975 log.trace(" Total stop_world time = %8.2f s.",
1976 (_init_times.sum() + _remark_times.sum() + _cleanup_times.sum())/1000.0);
1977 log.trace(" Total concurrent time = %8.2f s (%8.2f s marking).",
1978 cm_thread()->vtime_accum(), cm_thread()->vtime_mark_accum());
1979 }
1980
1981 void G1ConcurrentMark::print_worker_threads_on(outputStream* st) const {
1982 _concurrent_workers->print_worker_threads_on(st);
1983 }
1984
1985 void G1ConcurrentMark::threads_do(ThreadClosure* tc) const {
1986 _concurrent_workers->threads_do(tc);
1987 }
1988
1989 void G1ConcurrentMark::print_on_error(outputStream* st) const {
1990 st->print_cr("Marking Bits (Prev, Next): (CMBitMap*) " PTR_FORMAT ", (CMBitMap*) " PTR_FORMAT,
1991 p2i(_prev_mark_bitmap), p2i(_next_mark_bitmap));
1992 _prev_mark_bitmap->print_on_error(st, " Prev Bits: ");
1993 _next_mark_bitmap->print_on_error(st, " Next Bits: ");
1994 }
1995
1996 static ReferenceProcessor* get_cm_oop_closure_ref_processor(G1CollectedHeap* g1h) {
1997 ReferenceProcessor* result = g1h->ref_processor_cm();
1998 assert(result != NULL, "CM reference processor should not be NULL");
1999 return result;
2000 }
2001
2002 G1CMOopClosure::G1CMOopClosure(G1CollectedHeap* g1h,
2003 G1CMTask* task)
2004 : MetadataAwareOopClosure(get_cm_oop_closure_ref_processor(g1h)),
2005 _g1h(g1h), _task(task)
2006 { }
2007
2008 void G1CMTask::setup_for_region(HeapRegion* hr) {
2009 assert(hr != NULL,
2010 "claim_region() should have filtered out NULL regions");
2011 _curr_region = hr;
2012 _finger = hr->bottom();
2013 update_region_limit();
2014 }
2015
2016 void G1CMTask::update_region_limit() {
2017 HeapRegion* hr = _curr_region;
2018 HeapWord* bottom = hr->bottom();
2019 HeapWord* limit = hr->next_top_at_mark_start();
2020
2021 if (limit == bottom) {
2022 // The region was collected underneath our feet.
2023 // We set the finger to bottom to ensure that the bitmap
2024 // iteration that will follow this will not do anything.
2025 // (this is not a condition that holds when we set the region up,
2026 // as the region is not supposed to be empty in the first place)
2027 _finger = bottom;
2028 } else if (limit >= _region_limit) {
2029 assert(limit >= _finger, "peace of mind");
2030 } else {
2031 assert(limit < _region_limit, "only way to get here");
2032 // This can happen under some pretty unusual circumstances. An
2033 // evacuation pause empties the region underneath our feet (NTAMS
2034 // at bottom). We then do some allocation in the region (NTAMS
2035 // stays at bottom), followed by the region being used as a GC
2036 // alloc region (NTAMS will move to top() and the objects
2037 // originally below it will be grayed). All objects now marked in
2038 // the region are explicitly grayed, if below the global finger,
2039 // and we do not need in fact to scan anything else. So, we simply
2040 // set _finger to be limit to ensure that the bitmap iteration
2041 // doesn't do anything.
2042 _finger = limit;
2043 }
2044
2045 _region_limit = limit;
2046 }
2047
2048 void G1CMTask::giveup_current_region() {
2049 assert(_curr_region != NULL, "invariant");
2050 clear_region_fields();
2051 }
2052
2053 void G1CMTask::clear_region_fields() {
2054 // Values for these three fields that indicate that we're not
2055 // holding on to a region.
2056 _curr_region = NULL;
2057 _finger = NULL;
2058 _region_limit = NULL;
2059 }
2060
2061 void G1CMTask::set_cm_oop_closure(G1CMOopClosure* cm_oop_closure) {
2062 if (cm_oop_closure == NULL) {
2063 assert(_cm_oop_closure != NULL, "invariant");
2064 } else {
2065 assert(_cm_oop_closure == NULL, "invariant");
2066 }
2067 _cm_oop_closure = cm_oop_closure;
2068 }
2069
2070 void G1CMTask::reset(G1CMBitMap* next_mark_bitmap) {
2071 guarantee(next_mark_bitmap != NULL, "invariant");
2072 _next_mark_bitmap = next_mark_bitmap;
2073 clear_region_fields();
2074
2075 _calls = 0;
2076 _elapsed_time_ms = 0.0;
2077 _termination_time_ms = 0.0;
2078 _termination_start_time_ms = 0.0;
2079
2080 _mark_stats_cache.reset();
2081 }
2082
2083 bool G1CMTask::should_exit_termination() {
2084 regular_clock_call();
2085 // This is called when we are in the termination protocol. We should
2086 // quit if, for some reason, this task wants to abort or the global
2087 // stack is not empty (this means that we can get work from it).
2088 return !_cm->mark_stack_empty() || has_aborted();
2089 }
2090
2091 void G1CMTask::reached_limit() {
2092 assert(_words_scanned >= _words_scanned_limit ||
2093 _refs_reached >= _refs_reached_limit ,
2094 "shouldn't have been called otherwise");
2095 regular_clock_call();
2096 }
2097
2098 void G1CMTask::regular_clock_call() {
2099 if (has_aborted()) {
2100 return;
2101 }
2102
2103 // First, we need to recalculate the words scanned and refs reached
2104 // limits for the next clock call.
2105 recalculate_limits();
2106
2107 // During the regular clock call we do the following
2108
2109 // (1) If an overflow has been flagged, then we abort.
2110 if (_cm->has_overflown()) {
2111 set_has_aborted();
2112 return;
2113 }
2114
2115 // If we are not concurrent (i.e. we're doing remark) we don't need
2116 // to check anything else. The other steps are only needed during
2117 // the concurrent marking phase.
2118 if (!_cm->concurrent()) {
2119 return;
2120 }
2121
2122 // (2) If marking has been aborted for Full GC, then we also abort.
2123 if (_cm->has_aborted()) {
2124 set_has_aborted();
2125 return;
2126 }
2127
2128 double curr_time_ms = os::elapsedVTime() * 1000.0;
2129
2130 // (4) We check whether we should yield. If we have to, then we abort.
2131 if (SuspendibleThreadSet::should_yield()) {
2132 // We should yield. To do this we abort the task. The caller is
2133 // responsible for yielding.
2134 set_has_aborted();
2135 return;
2136 }
2137
2138 // (5) We check whether we've reached our time quota. If we have,
2139 // then we abort.
2140 double elapsed_time_ms = curr_time_ms - _start_time_ms;
2141 if (elapsed_time_ms > _time_target_ms) {
2142 set_has_aborted();
2143 _has_timed_out = true;
2144 return;
2145 }
2146
2147 // (6) Finally, we check whether there are enough completed STAB
2148 // buffers available for processing. If there are, we abort.
2149 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
2150 if (!_draining_satb_buffers && satb_mq_set.process_completed_buffers()) {
2151 // we do need to process SATB buffers, we'll abort and restart
2152 // the marking task to do so
2153 set_has_aborted();
2154 return;
2155 }
2156 }
2157
2158 void G1CMTask::recalculate_limits() {
2159 _real_words_scanned_limit = _words_scanned + words_scanned_period;
2160 _words_scanned_limit = _real_words_scanned_limit;
2161
2162 _real_refs_reached_limit = _refs_reached + refs_reached_period;
2163 _refs_reached_limit = _real_refs_reached_limit;
2164 }
2165
2166 void G1CMTask::decrease_limits() {
2167 // This is called when we believe that we're going to do an infrequent
2168 // operation which will increase the per byte scanned cost (i.e. move
2169 // entries to/from the global stack). It basically tries to decrease the
2170 // scanning limit so that the clock is called earlier.
2171
2172 _words_scanned_limit = _real_words_scanned_limit - 3 * words_scanned_period / 4;
2173 _refs_reached_limit = _real_refs_reached_limit - 3 * refs_reached_period / 4;
2174 }
2175
2176 void G1CMTask::move_entries_to_global_stack() {
2177 // Local array where we'll store the entries that will be popped
2178 // from the local queue.
2179 G1TaskQueueEntry buffer[G1CMMarkStack::EntriesPerChunk];
2180
2181 size_t n = 0;
2182 G1TaskQueueEntry task_entry;
2183 while (n < G1CMMarkStack::EntriesPerChunk && _task_queue->pop_local(task_entry)) {
2184 buffer[n] = task_entry;
2185 ++n;
2186 }
2187 if (n < G1CMMarkStack::EntriesPerChunk) {
2188 buffer[n] = G1TaskQueueEntry();
2189 }
2190
2191 if (n > 0) {
2192 if (!_cm->mark_stack_push(buffer)) {
2193 set_has_aborted();
2194 }
2195 }
2196
2197 // This operation was quite expensive, so decrease the limits.
2198 decrease_limits();
2199 }
2200
2201 bool G1CMTask::get_entries_from_global_stack() {
2202 // Local array where we'll store the entries that will be popped
2203 // from the global stack.
2204 G1TaskQueueEntry buffer[G1CMMarkStack::EntriesPerChunk];
2205
2206 if (!_cm->mark_stack_pop(buffer)) {
2207 return false;
2208 }
2209
2210 // We did actually pop at least one entry.
2211 for (size_t i = 0; i < G1CMMarkStack::EntriesPerChunk; ++i) {
2212 G1TaskQueueEntry task_entry = buffer[i];
2213 if (task_entry.is_null()) {
2214 break;
2215 }
2216 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()));
2217 bool success = _task_queue->push(task_entry);
2218 // We only call this when the local queue is empty or under a
2219 // given target limit. So, we do not expect this push to fail.
2220 assert(success, "invariant");
2221 }
2222
2223 // This operation was quite expensive, so decrease the limits
2224 decrease_limits();
2225 return true;
2226 }
2227
2228 void G1CMTask::drain_local_queue(bool partially) {
2229 if (has_aborted()) {
2230 return;
2231 }
2232
2233 // Decide what the target size is, depending whether we're going to
2234 // drain it partially (so that other tasks can steal if they run out
2235 // of things to do) or totally (at the very end).
2236 size_t target_size;
2237 if (partially) {
2238 target_size = MIN2((size_t)_task_queue->max_elems()/3, GCDrainStackTargetSize);
2239 } else {
2240 target_size = 0;
2241 }
2242
2243 if (_task_queue->size() > target_size) {
2244 G1TaskQueueEntry entry;
2245 bool ret = _task_queue->pop_local(entry);
2246 while (ret) {
2247 scan_task_entry(entry);
2248 if (_task_queue->size() <= target_size || has_aborted()) {
2249 ret = false;
2250 } else {
2251 ret = _task_queue->pop_local(entry);
2252 }
2253 }
2254 }
2255 }
2256
2257 void G1CMTask::drain_global_stack(bool partially) {
2258 if (has_aborted()) {
2259 return;
2260 }
2261
2262 // We have a policy to drain the local queue before we attempt to
2263 // drain the global stack.
2264 assert(partially || _task_queue->size() == 0, "invariant");
2265
2266 // Decide what the target size is, depending whether we're going to
2267 // drain it partially (so that other tasks can steal if they run out
2268 // of things to do) or totally (at the very end).
2269 // Notice that when draining the global mark stack partially, due to the racyness
2270 // of the mark stack size update we might in fact drop below the target. But,
2271 // this is not a problem.
2272 // In case of total draining, we simply process until the global mark stack is
2273 // totally empty, disregarding the size counter.
2274 if (partially) {
2275 size_t const target_size = _cm->partial_mark_stack_size_target();
2276 while (!has_aborted() && _cm->mark_stack_size() > target_size) {
2277 if (get_entries_from_global_stack()) {
2278 drain_local_queue(partially);
2279 }
2280 }
2281 } else {
2282 while (!has_aborted() && get_entries_from_global_stack()) {
2283 drain_local_queue(partially);
2284 }
2285 }
2286 }
2287
2288 // SATB Queue has several assumptions on whether to call the par or
2289 // non-par versions of the methods. this is why some of the code is
2290 // replicated. We should really get rid of the single-threaded version
2291 // of the code to simplify things.
2292 void G1CMTask::drain_satb_buffers() {
2293 if (has_aborted()) {
2294 return;
2295 }
2296
2297 // We set this so that the regular clock knows that we're in the
2298 // middle of draining buffers and doesn't set the abort flag when it
2299 // notices that SATB buffers are available for draining. It'd be
2300 // very counter productive if it did that. :-)
2301 _draining_satb_buffers = true;
2302
2303 G1CMSATBBufferClosure satb_cl(this, _g1h);
2304 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
2305
2306 // This keeps claiming and applying the closure to completed buffers
2307 // until we run out of buffers or we need to abort.
2308 while (!has_aborted() &&
2309 satb_mq_set.apply_closure_to_completed_buffer(&satb_cl)) {
2310 regular_clock_call();
2311 }
2312
2313 _draining_satb_buffers = false;
2314
2315 assert(has_aborted() ||
2316 _cm->concurrent() ||
2317 satb_mq_set.completed_buffers_num() == 0, "invariant");
2318
2319 // again, this was a potentially expensive operation, decrease the
2320 // limits to get the regular clock call early
2321 decrease_limits();
2322 }
2323
2324 void G1CMTask::clear_mark_stats_cache(uint region_idx) {
2325 _mark_stats_cache.reset(region_idx);
2326 }
2327
2328 Pair<size_t, size_t> G1CMTask::flush_mark_stats_cache() {
2329 return _mark_stats_cache.evict_all();
2330 }
2331
2332 void G1CMTask::print_stats() {
2333 log_debug(gc, stats)("Marking Stats, task = %u, calls = %u", _worker_id, _calls);
2334 log_debug(gc, stats)(" Elapsed time = %1.2lfms, Termination time = %1.2lfms",
2335 _elapsed_time_ms, _termination_time_ms);
2336 log_debug(gc, stats)(" Step Times (cum): num = %d, avg = %1.2lfms, sd = %1.2lfms max = %1.2lfms, total = %1.2lfms",
2337 _step_times_ms.num(),
2338 _step_times_ms.avg(),
2339 _step_times_ms.sd(),
2340 _step_times_ms.maximum(),
2341 _step_times_ms.sum());
2342 size_t const hits = _mark_stats_cache.hits();
2343 size_t const misses = _mark_stats_cache.misses();
2344 log_debug(gc, stats)(" Mark Stats Cache: hits " SIZE_FORMAT " misses " SIZE_FORMAT " ratio %.3f",
2345 hits, misses, percent_of(hits, hits + misses));
2346 }
2347
2348 bool G1ConcurrentMark::try_stealing(uint worker_id, int* hash_seed, G1TaskQueueEntry& task_entry) {
2349 return _task_queues->steal(worker_id, hash_seed, task_entry);
2350 }
2351
2352 /*****************************************************************************
2353
2354 The do_marking_step(time_target_ms, ...) method is the building
2355 block of the parallel marking framework. It can be called in parallel
2356 with other invocations of do_marking_step() on different tasks
2357 (but only one per task, obviously) and concurrently with the
2358 mutator threads, or during remark, hence it eliminates the need
2359 for two versions of the code. When called during remark, it will
2360 pick up from where the task left off during the concurrent marking
2361 phase. Interestingly, tasks are also claimable during evacuation
2362 pauses too, since do_marking_step() ensures that it aborts before
2363 it needs to yield.
2364
2365 The data structures that it uses to do marking work are the
2366 following:
2367
2368 (1) Marking Bitmap. If there are gray objects that appear only
2369 on the bitmap (this happens either when dealing with an overflow
2370 or when the initial marking phase has simply marked the roots
2371 and didn't push them on the stack), then tasks claim heap
2372 regions whose bitmap they then scan to find gray objects. A
2373 global finger indicates where the end of the last claimed region
2374 is. A local finger indicates how far into the region a task has
2375 scanned. The two fingers are used to determine how to gray an
2376 object (i.e. whether simply marking it is OK, as it will be
2377 visited by a task in the future, or whether it needs to be also
2378 pushed on a stack).
2379
2380 (2) Local Queue. The local queue of the task which is accessed
2381 reasonably efficiently by the task. Other tasks can steal from
2382 it when they run out of work. Throughout the marking phase, a
2383 task attempts to keep its local queue short but not totally
2384 empty, so that entries are available for stealing by other
2385 tasks. Only when there is no more work, a task will totally
2386 drain its local queue.
2387
2388 (3) Global Mark Stack. This handles local queue overflow. During
2389 marking only sets of entries are moved between it and the local
2390 queues, as access to it requires a mutex and more fine-grain
2391 interaction with it which might cause contention. If it
2392 overflows, then the marking phase should restart and iterate
2393 over the bitmap to identify gray objects. Throughout the marking
2394 phase, tasks attempt to keep the global mark stack at a small
2395 length but not totally empty, so that entries are available for
2396 popping by other tasks. Only when there is no more work, tasks
2397 will totally drain the global mark stack.
2398
2399 (4) SATB Buffer Queue. This is where completed SATB buffers are
2400 made available. Buffers are regularly removed from this queue
2401 and scanned for roots, so that the queue doesn't get too
2402 long. During remark, all completed buffers are processed, as
2403 well as the filled in parts of any uncompleted buffers.
2404
2405 The do_marking_step() method tries to abort when the time target
2406 has been reached. There are a few other cases when the
2407 do_marking_step() method also aborts:
2408
2409 (1) When the marking phase has been aborted (after a Full GC).
2410
2411 (2) When a global overflow (on the global stack) has been
2412 triggered. Before the task aborts, it will actually sync up with
2413 the other tasks to ensure that all the marking data structures
2414 (local queues, stacks, fingers etc.) are re-initialized so that
2415 when do_marking_step() completes, the marking phase can
2416 immediately restart.
2417
2418 (3) When enough completed SATB buffers are available. The
2419 do_marking_step() method only tries to drain SATB buffers right
2420 at the beginning. So, if enough buffers are available, the
2421 marking step aborts and the SATB buffers are processed at
2422 the beginning of the next invocation.
2423
2424 (4) To yield. when we have to yield then we abort and yield
2425 right at the end of do_marking_step(). This saves us from a lot
2426 of hassle as, by yielding we might allow a Full GC. If this
2427 happens then objects will be compacted underneath our feet, the
2428 heap might shrink, etc. We save checking for this by just
2429 aborting and doing the yield right at the end.
2430
2431 From the above it follows that the do_marking_step() method should
2432 be called in a loop (or, otherwise, regularly) until it completes.
2433
2434 If a marking step completes without its has_aborted() flag being
2435 true, it means it has completed the current marking phase (and
2436 also all other marking tasks have done so and have all synced up).
2437
2438 A method called regular_clock_call() is invoked "regularly" (in
2439 sub ms intervals) throughout marking. It is this clock method that
2440 checks all the abort conditions which were mentioned above and
2441 decides when the task should abort. A work-based scheme is used to
2442 trigger this clock method: when the number of object words the
2443 marking phase has scanned or the number of references the marking
2444 phase has visited reach a given limit. Additional invocations to
2445 the method clock have been planted in a few other strategic places
2446 too. The initial reason for the clock method was to avoid calling
2447 vtime too regularly, as it is quite expensive. So, once it was in
2448 place, it was natural to piggy-back all the other conditions on it
2449 too and not constantly check them throughout the code.
2450
2451 If do_termination is true then do_marking_step will enter its
2452 termination protocol.
2453
2454 The value of is_serial must be true when do_marking_step is being
2455 called serially (i.e. by the VMThread) and do_marking_step should
2456 skip any synchronization in the termination and overflow code.
2457 Examples include the serial remark code and the serial reference
2458 processing closures.
2459
2460 The value of is_serial must be false when do_marking_step is
2461 being called by any of the worker threads in a work gang.
2462 Examples include the concurrent marking code (CMMarkingTask),
2463 the MT remark code, and the MT reference processing closures.
2464
2465 *****************************************************************************/
2466
2467 void G1CMTask::do_marking_step(double time_target_ms,
2468 bool do_termination,
2469 bool is_serial) {
2470 assert(time_target_ms >= 1.0, "minimum granularity is 1ms");
2471
2472 _start_time_ms = os::elapsedVTime() * 1000.0;
2473
2474 // If do_stealing is true then do_marking_step will attempt to
2475 // steal work from the other G1CMTasks. It only makes sense to
2476 // enable stealing when the termination protocol is enabled
2477 // and do_marking_step() is not being called serially.
2478 bool do_stealing = do_termination && !is_serial;
2479
2480 double diff_prediction_ms = _g1h->g1_policy()->predictor().get_new_prediction(&_marking_step_diffs_ms);
2481 _time_target_ms = time_target_ms - diff_prediction_ms;
2482
2483 // set up the variables that are used in the work-based scheme to
2484 // call the regular clock method
2485 _words_scanned = 0;
2486 _refs_reached = 0;
2487 recalculate_limits();
2488
2489 // clear all flags
2490 clear_has_aborted();
2491 _has_timed_out = false;
2492 _draining_satb_buffers = false;
2493
2494 ++_calls;
2495
2496 // Set up the bitmap and oop closures. Anything that uses them is
2497 // eventually called from this method, so it is OK to allocate these
2498 // statically.
2499 G1CMBitMapClosure bitmap_closure(this, _cm);
2500 G1CMOopClosure cm_oop_closure(_g1h, this);
2501 set_cm_oop_closure(&cm_oop_closure);
2502
2503 if (_cm->has_overflown()) {
2504 // This can happen if the mark stack overflows during a GC pause
2505 // and this task, after a yield point, restarts. We have to abort
2506 // as we need to get into the overflow protocol which happens
2507 // right at the end of this task.
2508 set_has_aborted();
2509 }
2510
2511 // First drain any available SATB buffers. After this, we will not
2512 // look at SATB buffers before the next invocation of this method.
2513 // If enough completed SATB buffers are queued up, the regular clock
2514 // will abort this task so that it restarts.
2515 drain_satb_buffers();
2516 // ...then partially drain the local queue and the global stack
2517 drain_local_queue(true);
2518 drain_global_stack(true);
2519
2520 do {
2521 if (!has_aborted() && _curr_region != NULL) {
2522 // This means that we're already holding on to a region.
2523 assert(_finger != NULL, "if region is not NULL, then the finger "
2524 "should not be NULL either");
2525
2526 // We might have restarted this task after an evacuation pause
2527 // which might have evacuated the region we're holding on to
2528 // underneath our feet. Let's read its limit again to make sure
2529 // that we do not iterate over a region of the heap that
2530 // contains garbage (update_region_limit() will also move
2531 // _finger to the start of the region if it is found empty).
2532 update_region_limit();
2533 // We will start from _finger not from the start of the region,
2534 // as we might be restarting this task after aborting half-way
2535 // through scanning this region. In this case, _finger points to
2536 // the address where we last found a marked object. If this is a
2537 // fresh region, _finger points to start().
2538 MemRegion mr = MemRegion(_finger, _region_limit);
2539
2540 assert(!_curr_region->is_humongous() || mr.start() == _curr_region->bottom(),
2541 "humongous regions should go around loop once only");
2542
2543 // Some special cases:
2544 // If the memory region is empty, we can just give up the region.
2545 // If the current region is humongous then we only need to check
2546 // the bitmap for the bit associated with the start of the object,
2547 // scan the object if it's live, and give up the region.
2548 // Otherwise, let's iterate over the bitmap of the part of the region
2549 // that is left.
2550 // If the iteration is successful, give up the region.
2551 if (mr.is_empty()) {
2552 giveup_current_region();
2553 regular_clock_call();
2554 } else if (_curr_region->is_humongous() && mr.start() == _curr_region->bottom()) {
2555 if (_next_mark_bitmap->is_marked(mr.start())) {
2556 // The object is marked - apply the closure
2557 bitmap_closure.do_addr(mr.start());
2558 }
2559 // Even if this task aborted while scanning the humongous object
2560 // we can (and should) give up the current region.
2561 giveup_current_region();
2562 regular_clock_call();
2563 } else if (_next_mark_bitmap->iterate(&bitmap_closure, mr)) {
2564 giveup_current_region();
2565 regular_clock_call();
2566 } else {
2567 assert(has_aborted(), "currently the only way to do so");
2568 // The only way to abort the bitmap iteration is to return
2569 // false from the do_bit() method. However, inside the
2570 // do_bit() method we move the _finger to point to the
2571 // object currently being looked at. So, if we bail out, we
2572 // have definitely set _finger to something non-null.
2573 assert(_finger != NULL, "invariant");
2574
2575 // Region iteration was actually aborted. So now _finger
2576 // points to the address of the object we last scanned. If we
2577 // leave it there, when we restart this task, we will rescan
2578 // the object. It is easy to avoid this. We move the finger by
2579 // enough to point to the next possible object header.
2580 assert(_finger < _region_limit, "invariant");
2581 HeapWord* const new_finger = _finger + ((oop)_finger)->size();
2582 // Check if bitmap iteration was aborted while scanning the last object
2583 if (new_finger >= _region_limit) {
2584 giveup_current_region();
2585 } else {
2586 move_finger_to(new_finger);
2587 }
2588 }
2589 }
2590 // At this point we have either completed iterating over the
2591 // region we were holding on to, or we have aborted.
2592
2593 // We then partially drain the local queue and the global stack.
2594 // (Do we really need this?)
2595 drain_local_queue(true);
2596 drain_global_stack(true);
2597
2598 // Read the note on the claim_region() method on why it might
2599 // return NULL with potentially more regions available for
2600 // claiming and why we have to check out_of_regions() to determine
2601 // whether we're done or not.
2602 while (!has_aborted() && _curr_region == NULL && !_cm->out_of_regions()) {
2603 // We are going to try to claim a new region. We should have
2604 // given up on the previous one.
2605 // Separated the asserts so that we know which one fires.
2606 assert(_curr_region == NULL, "invariant");
2607 assert(_finger == NULL, "invariant");
2608 assert(_region_limit == NULL, "invariant");
2609 HeapRegion* claimed_region = _cm->claim_region(_worker_id);
2610 if (claimed_region != NULL) {
2611 // Yes, we managed to claim one
2612 setup_for_region(claimed_region);
2613 assert(_curr_region == claimed_region, "invariant");
2614 }
2615 // It is important to call the regular clock here. It might take
2616 // a while to claim a region if, for example, we hit a large
2617 // block of empty regions. So we need to call the regular clock
2618 // method once round the loop to make sure it's called
2619 // frequently enough.
2620 regular_clock_call();
2621 }
2622
2623 if (!has_aborted() && _curr_region == NULL) {
2624 assert(_cm->out_of_regions(),
2625 "at this point we should be out of regions");
2626 }
2627 } while ( _curr_region != NULL && !has_aborted());
2628
2629 if (!has_aborted()) {
2630 // We cannot check whether the global stack is empty, since other
2631 // tasks might be pushing objects to it concurrently.
2632 assert(_cm->out_of_regions(),
2633 "at this point we should be out of regions");
2634 // Try to reduce the number of available SATB buffers so that
2635 // remark has less work to do.
2636 drain_satb_buffers();
2637 }
2638
2639 // Since we've done everything else, we can now totally drain the
2640 // local queue and global stack.
2641 drain_local_queue(false);
2642 drain_global_stack(false);
2643
2644 // Attempt at work stealing from other task's queues.
2645 if (do_stealing && !has_aborted()) {
2646 // We have not aborted. This means that we have finished all that
2647 // we could. Let's try to do some stealing...
2648
2649 // We cannot check whether the global stack is empty, since other
2650 // tasks might be pushing objects to it concurrently.
2651 assert(_cm->out_of_regions() && _task_queue->size() == 0,
2652 "only way to reach here");
2653 while (!has_aborted()) {
2654 G1TaskQueueEntry entry;
2655 if (_cm->try_stealing(_worker_id, &_hash_seed, entry)) {
2656 scan_task_entry(entry);
2657
2658 // And since we're towards the end, let's totally drain the
2659 // local queue and global stack.
2660 drain_local_queue(false);
2661 drain_global_stack(false);
2662 } else {
2663 break;
2664 }
2665 }
2666 }
2667
2668 // We still haven't aborted. Now, let's try to get into the
2669 // termination protocol.
2670 if (do_termination && !has_aborted()) {
2671 // We cannot check whether the global stack is empty, since other
2672 // tasks might be concurrently pushing objects on it.
2673 // Separated the asserts so that we know which one fires.
2674 assert(_cm->out_of_regions(), "only way to reach here");
2675 assert(_task_queue->size() == 0, "only way to reach here");
2676 _termination_start_time_ms = os::elapsedVTime() * 1000.0;
2677
2678 // The G1CMTask class also extends the TerminatorTerminator class,
2679 // hence its should_exit_termination() method will also decide
2680 // whether to exit the termination protocol or not.
2681 bool finished = (is_serial ||
2682 _cm->terminator()->offer_termination(this));
2683 double termination_end_time_ms = os::elapsedVTime() * 1000.0;
2684 _termination_time_ms +=
2685 termination_end_time_ms - _termination_start_time_ms;
2686
2687 if (finished) {
2688 // We're all done.
2689
2690 // We can now guarantee that the global stack is empty, since
2691 // all other tasks have finished. We separated the guarantees so
2692 // that, if a condition is false, we can immediately find out
2693 // which one.
2694 guarantee(_cm->out_of_regions(), "only way to reach here");
2695 guarantee(_cm->mark_stack_empty(), "only way to reach here");
2696 guarantee(_task_queue->size() == 0, "only way to reach here");
2697 guarantee(!_cm->has_overflown(), "only way to reach here");
2698 } else {
2699 // Apparently there's more work to do. Let's abort this task. It
2700 // will restart it and we can hopefully find more things to do.
2701 set_has_aborted();
2702 }
2703 }
2704
2705 // Mainly for debugging purposes to make sure that a pointer to the
2706 // closure which was statically allocated in this frame doesn't
2707 // escape it by accident.
2708 set_cm_oop_closure(NULL);
2709 double end_time_ms = os::elapsedVTime() * 1000.0;
2710 double elapsed_time_ms = end_time_ms - _start_time_ms;
2711 // Update the step history.
2712 _step_times_ms.add(elapsed_time_ms);
2713
2714 if (has_aborted()) {
2715 // The task was aborted for some reason.
2716 if (_has_timed_out) {
2717 double diff_ms = elapsed_time_ms - _time_target_ms;
2718 // Keep statistics of how well we did with respect to hitting
2719 // our target only if we actually timed out (if we aborted for
2720 // other reasons, then the results might get skewed).
2721 _marking_step_diffs_ms.add(diff_ms);
2722 }
2723
2724 if (_cm->has_overflown()) {
2725 // This is the interesting one. We aborted because a global
2726 // overflow was raised. This means we have to restart the
2727 // marking phase and start iterating over regions. However, in
2728 // order to do this we have to make sure that all tasks stop
2729 // what they are doing and re-initialize in a safe manner. We
2730 // will achieve this with the use of two barrier sync points.
2731
2732 if (!is_serial) {
2733 // We only need to enter the sync barrier if being called
2734 // from a parallel context
2735 _cm->enter_first_sync_barrier(_worker_id);
2736
2737 // When we exit this sync barrier we know that all tasks have
2738 // stopped doing marking work. So, it's now safe to
2739 // re-initialize our data structures.
2740 }
2741
2742 clear_region_fields();
2743 flush_mark_stats_cache();
2744
2745 if (!is_serial) {
2746 // If we're executing the concurrent phase of marking, reset the marking
2747 // state; otherwise the marking state is reset after reference processing,
2748 // during the remark pause.
2749 // If we reset here as a result of an overflow during the remark we will
2750 // see assertion failures from any subsequent set_concurrency_and_phase()
2751 // calls.
2752 if (_cm->concurrent() && _worker_id == 0) {
2753 // Worker 0 is responsible for clearing the global data structures because
2754 // of an overflow. During STW we should not clear the overflow flag (in
2755 // G1ConcurrentMark::reset_marking_state()) since we rely on it being true when we exit
2756 // method to abort the pause and restart concurrent marking.
2757 _cm->reset_marking_for_restart();
2758
2759 log_info(gc, marking)("Concurrent Mark reset for overflow");
2760 }
2761
2762 // ...and enter the second barrier.
2763 _cm->enter_second_sync_barrier(_worker_id);
2764 }
2765 // At this point, if we're during the concurrent phase of
2766 // marking, everything has been re-initialized and we're
2767 // ready to restart.
2768 }
2769 }
2770 }
2771
2772 G1CMTask::G1CMTask(uint worker_id,
2773 G1ConcurrentMark* cm,
2774 G1CMTaskQueue* task_queue,
2775 G1RegionMarkStats* mark_stats,
2776 uint max_regions) :
2777 _objArray_processor(this),
2778 _worker_id(worker_id),
2779 _g1h(G1CollectedHeap::heap()),
2780 _cm(cm),
2781 _next_mark_bitmap(NULL),
2782 _task_queue(task_queue),
2783 _mark_stats_cache(mark_stats, max_regions, RegionMarkStatsCacheSize),
2784 _calls(0),
2785 _time_target_ms(0.0),
2786 _start_time_ms(0.0),
2787 _cm_oop_closure(NULL),
2788 _curr_region(NULL),
2789 _finger(NULL),
2790 _region_limit(NULL),
2791 _words_scanned(0),
2792 _words_scanned_limit(0),
2793 _real_words_scanned_limit(0),
2794 _refs_reached(0),
2795 _refs_reached_limit(0),
2796 _real_refs_reached_limit(0),
2797 _hash_seed(17),
2798 _has_aborted(false),
2799 _has_timed_out(false),
2800 _draining_satb_buffers(false),
2801 _step_times_ms(),
2802 _elapsed_time_ms(0.0),
2803 _termination_time_ms(0.0),
2804 _termination_start_time_ms(0.0),
2805 _marking_step_diffs_ms()
2806 {
2807 guarantee(task_queue != NULL, "invariant");
2808
2809 _marking_step_diffs_ms.add(0.5);
2810 }
2811
2812 // These are formatting macros that are used below to ensure
2813 // consistent formatting. The *_H_* versions are used to format the
2814 // header for a particular value and they should be kept consistent
2815 // with the corresponding macro. Also note that most of the macros add
2816 // the necessary white space (as a prefix) which makes them a bit
2817 // easier to compose.
2818
2819 // All the output lines are prefixed with this string to be able to
2820 // identify them easily in a large log file.
2821 #define G1PPRL_LINE_PREFIX "###"
2822
2823 #define G1PPRL_ADDR_BASE_FORMAT " " PTR_FORMAT "-" PTR_FORMAT
2824 #ifdef _LP64
2825 #define G1PPRL_ADDR_BASE_H_FORMAT " %37s"
2826 #else // _LP64
2827 #define G1PPRL_ADDR_BASE_H_FORMAT " %21s"
2828 #endif // _LP64
2829
2830 // For per-region info
2831 #define G1PPRL_TYPE_FORMAT " %-4s"
2832 #define G1PPRL_TYPE_H_FORMAT " %4s"
2833 #define G1PPRL_STATE_FORMAT " %-5s"
2834 #define G1PPRL_STATE_H_FORMAT " %5s"
2835 #define G1PPRL_BYTE_FORMAT " " SIZE_FORMAT_W(9)
2836 #define G1PPRL_BYTE_H_FORMAT " %9s"
2837 #define G1PPRL_DOUBLE_FORMAT " %14.1f"
2838 #define G1PPRL_DOUBLE_H_FORMAT " %14s"
2839
2840 // For summary info
2841 #define G1PPRL_SUM_ADDR_FORMAT(tag) " " tag ":" G1PPRL_ADDR_BASE_FORMAT
2842 #define G1PPRL_SUM_BYTE_FORMAT(tag) " " tag ": " SIZE_FORMAT
2843 #define G1PPRL_SUM_MB_FORMAT(tag) " " tag ": %1.2f MB"
2844 #define G1PPRL_SUM_MB_PERC_FORMAT(tag) G1PPRL_SUM_MB_FORMAT(tag) " / %1.2f %%"
2845
2846 G1PrintRegionLivenessInfoClosure::G1PrintRegionLivenessInfoClosure(const char* phase_name) :
2847 _total_used_bytes(0), _total_capacity_bytes(0),
2848 _total_prev_live_bytes(0), _total_next_live_bytes(0),
2849 _total_remset_bytes(0), _total_strong_code_roots_bytes(0)
2850 {
2851 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2852 MemRegion g1_reserved = g1h->g1_reserved();
2853 double now = os::elapsedTime();
2854
2855 // Print the header of the output.
2856 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX" PHASE %s @ %1.3f", phase_name, now);
2857 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX" HEAP"
2858 G1PPRL_SUM_ADDR_FORMAT("reserved")
2859 G1PPRL_SUM_BYTE_FORMAT("region-size"),
2860 p2i(g1_reserved.start()), p2i(g1_reserved.end()),
2861 HeapRegion::GrainBytes);
2862 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX);
2863 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX
2864 G1PPRL_TYPE_H_FORMAT
2865 G1PPRL_ADDR_BASE_H_FORMAT
2866 G1PPRL_BYTE_H_FORMAT
2867 G1PPRL_BYTE_H_FORMAT
2868 G1PPRL_BYTE_H_FORMAT
2869 G1PPRL_DOUBLE_H_FORMAT
2870 G1PPRL_BYTE_H_FORMAT
2871 G1PPRL_STATE_H_FORMAT
2872 G1PPRL_BYTE_H_FORMAT,
2873 "type", "address-range",
2874 "used", "prev-live", "next-live", "gc-eff",
2875 "remset", "state", "code-roots");
2876 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX
2877 G1PPRL_TYPE_H_FORMAT
2878 G1PPRL_ADDR_BASE_H_FORMAT
2879 G1PPRL_BYTE_H_FORMAT
2880 G1PPRL_BYTE_H_FORMAT
2881 G1PPRL_BYTE_H_FORMAT
2882 G1PPRL_DOUBLE_H_FORMAT
2883 G1PPRL_BYTE_H_FORMAT
2884 G1PPRL_STATE_H_FORMAT
2885 G1PPRL_BYTE_H_FORMAT,
2886 "", "",
2887 "(bytes)", "(bytes)", "(bytes)", "(bytes/ms)",
2888 "(bytes)", "", "(bytes)");
2889 }
2890
2891 bool G1PrintRegionLivenessInfoClosure::do_heap_region(HeapRegion* r) {
2892 const char* type = r->get_type_str();
2893 HeapWord* bottom = r->bottom();
2894 HeapWord* end = r->end();
2895 size_t capacity_bytes = r->capacity();
2896 size_t used_bytes = r->used();
2897 size_t prev_live_bytes = r->live_bytes();
2898 size_t next_live_bytes = r->next_live_bytes();
2899 double gc_eff = r->gc_efficiency();
2900 size_t remset_bytes = r->rem_set()->mem_size();
2901 size_t strong_code_roots_bytes = r->rem_set()->strong_code_roots_mem_size();
2902 const char* remset_type = r->rem_set()->get_short_state_str();
2903
2904 _total_used_bytes += used_bytes;
2905 _total_capacity_bytes += capacity_bytes;
2906 _total_prev_live_bytes += prev_live_bytes;
2907 _total_next_live_bytes += next_live_bytes;
2908 _total_remset_bytes += remset_bytes;
2909 _total_strong_code_roots_bytes += strong_code_roots_bytes;
2910
2911 // Print a line for this particular region.
2912 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX
2913 G1PPRL_TYPE_FORMAT
2914 G1PPRL_ADDR_BASE_FORMAT
2915 G1PPRL_BYTE_FORMAT
2916 G1PPRL_BYTE_FORMAT
2917 G1PPRL_BYTE_FORMAT
2918 G1PPRL_DOUBLE_FORMAT
2919 G1PPRL_BYTE_FORMAT
2920 G1PPRL_STATE_FORMAT
2921 G1PPRL_BYTE_FORMAT,
2922 type, p2i(bottom), p2i(end),
2923 used_bytes, prev_live_bytes, next_live_bytes, gc_eff,
2924 remset_bytes, remset_type, strong_code_roots_bytes);
2925
2926 return false;
2927 }
2928
2929 G1PrintRegionLivenessInfoClosure::~G1PrintRegionLivenessInfoClosure() {
2930 // add static memory usages to remembered set sizes
2931 _total_remset_bytes += HeapRegionRemSet::fl_mem_size() + HeapRegionRemSet::static_mem_size();
2932 // Print the footer of the output.
2933 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX);
2934 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX
2935 " SUMMARY"
2936 G1PPRL_SUM_MB_FORMAT("capacity")
2937 G1PPRL_SUM_MB_PERC_FORMAT("used")
2938 G1PPRL_SUM_MB_PERC_FORMAT("prev-live")
2939 G1PPRL_SUM_MB_PERC_FORMAT("next-live")
2940 G1PPRL_SUM_MB_FORMAT("remset")
2941 G1PPRL_SUM_MB_FORMAT("code-roots"),
2942 bytes_to_mb(_total_capacity_bytes),
2943 bytes_to_mb(_total_used_bytes),
2944 percent_of(_total_used_bytes, _total_capacity_bytes),
2945 bytes_to_mb(_total_prev_live_bytes),
2946 percent_of(_total_prev_live_bytes, _total_capacity_bytes),
2947 bytes_to_mb(_total_next_live_bytes),
2948 percent_of(_total_next_live_bytes, _total_capacity_bytes),
2949 bytes_to_mb(_total_remset_bytes),
2950 bytes_to_mb(_total_strong_code_roots_bytes));
2951 }