1 /*
2 * Copyright (c) 2001, 2020, 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/classLoaderDataGraph.hpp"
27 #include "code/codeCache.hpp"
28 #include "gc/g1/g1BarrierSet.hpp"
29 #include "gc/g1/g1CollectedHeap.inline.hpp"
30 #include "gc/g1/g1CollectorState.hpp"
31 #include "gc/g1/g1ConcurrentMark.inline.hpp"
32 #include "gc/g1/g1ConcurrentMarkThread.inline.hpp"
33 #include "gc/g1/g1DirtyCardQueue.hpp"
34 #include "gc/g1/g1HeapVerifier.hpp"
35 #include "gc/g1/g1OopClosures.inline.hpp"
36 #include "gc/g1/g1Policy.hpp"
37 #include "gc/g1/g1RegionMarkStatsCache.inline.hpp"
38 #include "gc/g1/g1StringDedup.hpp"
39 #include "gc/g1/g1ThreadLocalData.hpp"
40 #include "gc/g1/g1Trace.hpp"
41 #include "gc/g1/heapRegion.inline.hpp"
42 #include "gc/g1/heapRegionRemSet.hpp"
43 #include "gc/g1/heapRegionSet.inline.hpp"
44 #include "gc/shared/gcId.hpp"
45 #include "gc/shared/gcTimer.hpp"
46 #include "gc/shared/gcTraceTime.inline.hpp"
47 #include "gc/shared/gcVMOperations.hpp"
48 #include "gc/shared/genOopClosures.inline.hpp"
49 #include "gc/shared/referencePolicy.hpp"
50 #include "gc/shared/strongRootsScope.hpp"
51 #include "gc/shared/suspendibleThreadSet.hpp"
52 #include "gc/shared/taskTerminator.hpp"
53 #include "gc/shared/taskqueue.inline.hpp"
54 #include "gc/shared/weakProcessor.inline.hpp"
55 #include "gc/shared/workerPolicy.hpp"
56 #include "include/jvm.h"
57 #include "logging/log.hpp"
58 #include "memory/allocation.hpp"
59 #include "memory/iterator.hpp"
60 #include "memory/resourceArea.hpp"
61 #include "memory/universe.hpp"
62 #include "oops/access.inline.hpp"
63 #include "oops/oop.inline.hpp"
64 #include "runtime/atomic.hpp"
65 #include "runtime/handles.inline.hpp"
66 #include "runtime/java.hpp"
67 #include "runtime/orderAccess.hpp"
68 #include "runtime/prefetch.inline.hpp"
69 #include "services/memTracker.hpp"
70 #include "utilities/align.hpp"
71 #include "utilities/growableArray.hpp"
72
73 bool G1CMBitMapClosure::do_addr(HeapWord* const addr) {
74 assert(addr < _cm->finger(), "invariant");
75 assert(addr >= _task->finger(), "invariant");
76
77 // We move that task's local finger along.
78 _task->move_finger_to(addr);
79
80 _task->scan_task_entry(G1TaskQueueEntry::from_oop(oop(addr)));
81 // we only partially drain the local queue and global stack
82 _task->drain_local_queue(true);
83 _task->drain_global_stack(true);
84
85 // if the has_aborted flag has been raised, we need to bail out of
86 // the iteration
87 return !_task->has_aborted();
88 }
89
90 G1CMMarkStack::G1CMMarkStack() :
91 _max_chunk_capacity(0),
92 _base(NULL),
93 _chunk_capacity(0) {
94 set_empty();
95 }
96
97 bool G1CMMarkStack::resize(size_t new_capacity) {
98 assert(is_empty(), "Only resize when stack is empty.");
99 assert(new_capacity <= _max_chunk_capacity,
100 "Trying to resize stack to " SIZE_FORMAT " chunks when the maximum is " SIZE_FORMAT, new_capacity, _max_chunk_capacity);
101
102 TaskQueueEntryChunk* new_base = MmapArrayAllocator<TaskQueueEntryChunk>::allocate_or_null(new_capacity, mtGC);
103
104 if (new_base == NULL) {
105 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));
106 return false;
107 }
108 // Release old mapping.
109 if (_base != NULL) {
110 MmapArrayAllocator<TaskQueueEntryChunk>::free(_base, _chunk_capacity);
111 }
112
113 _base = new_base;
114 _chunk_capacity = new_capacity;
115 set_empty();
116
117 return true;
118 }
119
120 size_t G1CMMarkStack::capacity_alignment() {
121 return (size_t)lcm(os::vm_allocation_granularity(), sizeof(TaskQueueEntryChunk)) / sizeof(G1TaskQueueEntry);
122 }
123
124 bool G1CMMarkStack::initialize(size_t initial_capacity, size_t max_capacity) {
125 guarantee(_max_chunk_capacity == 0, "G1CMMarkStack already initialized.");
126
127 size_t const TaskEntryChunkSizeInVoidStar = sizeof(TaskQueueEntryChunk) / sizeof(G1TaskQueueEntry);
128
129 _max_chunk_capacity = align_up(max_capacity, capacity_alignment()) / TaskEntryChunkSizeInVoidStar;
130 size_t initial_chunk_capacity = align_up(initial_capacity, capacity_alignment()) / TaskEntryChunkSizeInVoidStar;
131
132 guarantee(initial_chunk_capacity <= _max_chunk_capacity,
133 "Maximum chunk capacity " SIZE_FORMAT " smaller than initial capacity " SIZE_FORMAT,
134 _max_chunk_capacity,
135 initial_chunk_capacity);
136
137 log_debug(gc)("Initialize mark stack with " SIZE_FORMAT " chunks, maximum " SIZE_FORMAT,
138 initial_chunk_capacity, _max_chunk_capacity);
139
140 return resize(initial_chunk_capacity);
141 }
142
143 void G1CMMarkStack::expand() {
144 if (_chunk_capacity == _max_chunk_capacity) {
145 log_debug(gc)("Can not expand overflow mark stack further, already at maximum capacity of " SIZE_FORMAT " chunks.", _chunk_capacity);
146 return;
147 }
148 size_t old_capacity = _chunk_capacity;
149 // Double capacity if possible
150 size_t new_capacity = MIN2(old_capacity * 2, _max_chunk_capacity);
151
152 if (resize(new_capacity)) {
153 log_debug(gc)("Expanded mark stack capacity from " SIZE_FORMAT " to " SIZE_FORMAT " chunks",
154 old_capacity, new_capacity);
155 } else {
156 log_warning(gc)("Failed to expand mark stack capacity from " SIZE_FORMAT " to " SIZE_FORMAT " chunks",
157 old_capacity, new_capacity);
158 }
159 }
160
161 G1CMMarkStack::~G1CMMarkStack() {
162 if (_base != NULL) {
163 MmapArrayAllocator<TaskQueueEntryChunk>::free(_base, _chunk_capacity);
164 }
165 }
166
167 void G1CMMarkStack::add_chunk_to_list(TaskQueueEntryChunk* volatile* list, TaskQueueEntryChunk* elem) {
168 elem->next = *list;
169 *list = elem;
170 }
171
172 void G1CMMarkStack::add_chunk_to_chunk_list(TaskQueueEntryChunk* elem) {
173 MutexLocker x(MarkStackChunkList_lock, Mutex::_no_safepoint_check_flag);
174 add_chunk_to_list(&_chunk_list, elem);
175 _chunks_in_chunk_list++;
176 }
177
178 void G1CMMarkStack::add_chunk_to_free_list(TaskQueueEntryChunk* elem) {
179 MutexLocker x(MarkStackFreeList_lock, Mutex::_no_safepoint_check_flag);
180 add_chunk_to_list(&_free_list, elem);
181 }
182
183 G1CMMarkStack::TaskQueueEntryChunk* G1CMMarkStack::remove_chunk_from_list(TaskQueueEntryChunk* volatile* list) {
184 TaskQueueEntryChunk* result = *list;
185 if (result != NULL) {
186 *list = (*list)->next;
187 }
188 return result;
189 }
190
191 G1CMMarkStack::TaskQueueEntryChunk* G1CMMarkStack::remove_chunk_from_chunk_list() {
192 MutexLocker x(MarkStackChunkList_lock, Mutex::_no_safepoint_check_flag);
193 TaskQueueEntryChunk* result = remove_chunk_from_list(&_chunk_list);
194 if (result != NULL) {
195 _chunks_in_chunk_list--;
196 }
197 return result;
198 }
199
200 G1CMMarkStack::TaskQueueEntryChunk* G1CMMarkStack::remove_chunk_from_free_list() {
201 MutexLocker x(MarkStackFreeList_lock, Mutex::_no_safepoint_check_flag);
202 return remove_chunk_from_list(&_free_list);
203 }
204
205 G1CMMarkStack::TaskQueueEntryChunk* G1CMMarkStack::allocate_new_chunk() {
206 // This dirty read of _hwm is okay because we only ever increase the _hwm in parallel code.
207 // Further this limits _hwm to a value of _chunk_capacity + #threads, avoiding
208 // wraparound of _hwm.
209 if (_hwm >= _chunk_capacity) {
210 return NULL;
211 }
212
213 size_t cur_idx = Atomic::fetch_and_add(&_hwm, 1u);
214 if (cur_idx >= _chunk_capacity) {
215 return NULL;
216 }
217
218 TaskQueueEntryChunk* result = ::new (&_base[cur_idx]) TaskQueueEntryChunk;
219 result->next = NULL;
220 return result;
221 }
222
223 bool G1CMMarkStack::par_push_chunk(G1TaskQueueEntry* ptr_arr) {
224 // Get a new chunk.
225 TaskQueueEntryChunk* new_chunk = remove_chunk_from_free_list();
226
227 if (new_chunk == NULL) {
228 // Did not get a chunk from the free list. Allocate from backing memory.
229 new_chunk = allocate_new_chunk();
230
231 if (new_chunk == NULL) {
232 return false;
233 }
234 }
235
236 Copy::conjoint_memory_atomic(ptr_arr, new_chunk->data, EntriesPerChunk * sizeof(G1TaskQueueEntry));
237
238 add_chunk_to_chunk_list(new_chunk);
239
240 return true;
241 }
242
243 bool G1CMMarkStack::par_pop_chunk(G1TaskQueueEntry* ptr_arr) {
244 TaskQueueEntryChunk* cur = remove_chunk_from_chunk_list();
245
246 if (cur == NULL) {
247 return false;
248 }
249
250 Copy::conjoint_memory_atomic(cur->data, ptr_arr, EntriesPerChunk * sizeof(G1TaskQueueEntry));
251
252 add_chunk_to_free_list(cur);
253 return true;
254 }
255
256 void G1CMMarkStack::set_empty() {
257 _chunks_in_chunk_list = 0;
258 _hwm = 0;
259 _chunk_list = NULL;
260 _free_list = NULL;
261 }
262
263 G1CMRootMemRegions::G1CMRootMemRegions(uint const max_regions) :
264 _root_regions(MemRegion::create_array(max_regions, mtGC)),
265 _max_regions(max_regions),
266 _num_root_regions(0),
267 _claimed_root_regions(0),
268 _scan_in_progress(false),
269 _should_abort(false) { }
270
271 G1CMRootMemRegions::~G1CMRootMemRegions() {
272 MemRegion::destroy_array(_root_regions, _max_regions);
273 }
274
275 void G1CMRootMemRegions::reset() {
276 _num_root_regions = 0;
277 }
278
279 void G1CMRootMemRegions::add(HeapWord* start, HeapWord* end) {
280 assert_at_safepoint();
281 size_t idx = Atomic::fetch_and_add(&_num_root_regions, 1u);
282 assert(idx < _max_regions, "Trying to add more root MemRegions than there is space " SIZE_FORMAT, _max_regions);
283 assert(start != NULL && end != NULL && start <= end, "Start (" PTR_FORMAT ") should be less or equal to "
284 "end (" PTR_FORMAT ")", p2i(start), p2i(end));
285 _root_regions[idx].set_start(start);
286 _root_regions[idx].set_end(end);
287 }
288
289 void G1CMRootMemRegions::prepare_for_scan() {
290 assert(!scan_in_progress(), "pre-condition");
291
292 _scan_in_progress = _num_root_regions > 0;
293
294 _claimed_root_regions = 0;
295 _should_abort = false;
296 }
297
298 const MemRegion* G1CMRootMemRegions::claim_next() {
299 if (_should_abort) {
300 // If someone has set the should_abort flag, we return NULL to
301 // force the caller to bail out of their loop.
302 return NULL;
303 }
304
305 if (_claimed_root_regions >= _num_root_regions) {
306 return NULL;
307 }
308
309 size_t claimed_index = Atomic::fetch_and_add(&_claimed_root_regions, 1u);
310 if (claimed_index < _num_root_regions) {
311 return &_root_regions[claimed_index];
312 }
313 return NULL;
314 }
315
316 uint G1CMRootMemRegions::num_root_regions() const {
317 return (uint)_num_root_regions;
318 }
319
320 void G1CMRootMemRegions::notify_scan_done() {
321 MutexLocker x(RootRegionScan_lock, Mutex::_no_safepoint_check_flag);
322 _scan_in_progress = false;
323 RootRegionScan_lock->notify_all();
324 }
325
326 void G1CMRootMemRegions::cancel_scan() {
327 notify_scan_done();
328 }
329
330 void G1CMRootMemRegions::scan_finished() {
331 assert(scan_in_progress(), "pre-condition");
332
333 if (!_should_abort) {
334 assert(_claimed_root_regions >= num_root_regions(),
335 "we should have claimed all root regions, claimed " SIZE_FORMAT ", length = %u",
336 _claimed_root_regions, num_root_regions());
337 }
338
339 notify_scan_done();
340 }
341
342 bool G1CMRootMemRegions::wait_until_scan_finished() {
343 if (!scan_in_progress()) {
344 return false;
345 }
346
347 {
348 MonitorLocker ml(RootRegionScan_lock, Mutex::_no_safepoint_check_flag);
349 while (scan_in_progress()) {
350 ml.wait();
351 }
352 }
353 return true;
354 }
355
356 G1ConcurrentMark::G1ConcurrentMark(G1CollectedHeap* g1h,
357 G1RegionToSpaceMapper* prev_bitmap_storage,
358 G1RegionToSpaceMapper* next_bitmap_storage) :
359 // _cm_thread set inside the constructor
360 _g1h(g1h),
361
362 _mark_bitmap_1(),
363 _mark_bitmap_2(),
364 _prev_mark_bitmap(&_mark_bitmap_1),
365 _next_mark_bitmap(&_mark_bitmap_2),
366
367 _heap(_g1h->reserved_region()),
368
369 _root_regions(_g1h->max_regions()),
370
371 _global_mark_stack(),
372
373 // _finger set in set_non_marking_state
374
375 _worker_id_offset(G1DirtyCardQueueSet::num_par_ids() + G1ConcRefinementThreads),
376 _max_num_tasks(ParallelGCThreads),
377 // _num_active_tasks set in set_non_marking_state()
378 // _tasks set inside the constructor
379
380 _task_queues(new G1CMTaskQueueSet((int) _max_num_tasks)),
381 _terminator((int) _max_num_tasks, _task_queues),
382
383 _first_overflow_barrier_sync(),
384 _second_overflow_barrier_sync(),
385
386 _has_overflown(false),
387 _concurrent(false),
388 _has_aborted(false),
389 _restart_for_overflow(false),
390 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
391 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()),
392
393 // _verbose_level set below
394
395 _init_times(),
396 _remark_times(),
397 _remark_mark_times(),
398 _remark_weak_ref_times(),
399 _cleanup_times(),
400 _total_cleanup_time(0.0),
401
402 _accum_task_vtime(NULL),
403
404 _concurrent_workers(NULL),
405 _num_concurrent_workers(0),
406 _max_concurrent_workers(0),
407
408 _region_mark_stats(NEW_C_HEAP_ARRAY(G1RegionMarkStats, _g1h->max_regions(), mtGC)),
409 _top_at_rebuild_starts(NEW_C_HEAP_ARRAY(HeapWord*, _g1h->max_regions(), mtGC))
410 {
411 assert(CGC_lock != NULL, "CGC_lock must be initialized");
412
413 _mark_bitmap_1.initialize(g1h->reserved_region(), prev_bitmap_storage);
414 _mark_bitmap_2.initialize(g1h->reserved_region(), next_bitmap_storage);
415
416 // Create & start ConcurrentMark thread.
417 _cm_thread = new G1ConcurrentMarkThread(this);
418 if (_cm_thread->osthread() == NULL) {
419 vm_shutdown_during_initialization("Could not create ConcurrentMarkThread");
420 }
421
422 log_debug(gc)("ConcGCThreads: %u offset %u", ConcGCThreads, _worker_id_offset);
423 log_debug(gc)("ParallelGCThreads: %u", ParallelGCThreads);
424
425 _num_concurrent_workers = ConcGCThreads;
426 _max_concurrent_workers = _num_concurrent_workers;
427
428 _concurrent_workers = new WorkGang("G1 Conc", _max_concurrent_workers, false, true);
429 _concurrent_workers->initialize_workers();
430
431 if (!_global_mark_stack.initialize(MarkStackSize, MarkStackSizeMax)) {
432 vm_exit_during_initialization("Failed to allocate initial concurrent mark overflow mark stack.");
433 }
434
435 _tasks = NEW_C_HEAP_ARRAY(G1CMTask*, _max_num_tasks, mtGC);
436 _accum_task_vtime = NEW_C_HEAP_ARRAY(double, _max_num_tasks, mtGC);
437
438 // so that the assertion in MarkingTaskQueue::task_queue doesn't fail
439 _num_active_tasks = _max_num_tasks;
440
441 for (uint i = 0; i < _max_num_tasks; ++i) {
442 G1CMTaskQueue* task_queue = new G1CMTaskQueue();
443 task_queue->initialize();
444 _task_queues->register_queue(i, task_queue);
445
446 _tasks[i] = new G1CMTask(i, this, task_queue, _region_mark_stats);
447
448 _accum_task_vtime[i] = 0.0;
449 }
450
451 reset_at_marking_complete();
452 }
453
454 void G1ConcurrentMark::reset() {
455 _has_aborted = false;
456
457 reset_marking_for_restart();
458
459 // Reset all tasks, since different phases will use different number of active
460 // threads. So, it's easiest to have all of them ready.
461 for (uint i = 0; i < _max_num_tasks; ++i) {
462 _tasks[i]->reset(_next_mark_bitmap);
463 }
464
465 uint max_regions = _g1h->max_regions();
466 for (uint i = 0; i < max_regions; i++) {
467 _top_at_rebuild_starts[i] = NULL;
468 _region_mark_stats[i].clear();
469 }
470 }
471
472 void G1ConcurrentMark::clear_statistics_in_region(uint region_idx) {
473 for (uint j = 0; j < _max_num_tasks; ++j) {
474 _tasks[j]->clear_mark_stats_cache(region_idx);
475 }
476 _top_at_rebuild_starts[region_idx] = NULL;
477 _region_mark_stats[region_idx].clear();
478 }
479
480 void G1ConcurrentMark::clear_statistics(HeapRegion* r) {
481 uint const region_idx = r->hrm_index();
482 if (r->is_humongous()) {
483 assert(r->is_starts_humongous(), "Got humongous continues region here");
484 uint const size_in_regions = (uint)_g1h->humongous_obj_size_in_regions(oop(r->humongous_start_region()->bottom())->size());
485 for (uint j = region_idx; j < (region_idx + size_in_regions); j++) {
486 clear_statistics_in_region(j);
487 }
488 } else {
489 clear_statistics_in_region(region_idx);
490 }
491 }
492
493 static void clear_mark_if_set(G1CMBitMap* bitmap, HeapWord* addr) {
494 if (bitmap->is_marked(addr)) {
495 bitmap->clear(addr);
496 }
497 }
498
499 void G1ConcurrentMark::humongous_object_eagerly_reclaimed(HeapRegion* r) {
500 assert_at_safepoint_on_vm_thread();
501
502 // Need to clear all mark bits of the humongous object.
503 clear_mark_if_set(_prev_mark_bitmap, r->bottom());
504 clear_mark_if_set(_next_mark_bitmap, r->bottom());
505
506 if (!_g1h->collector_state()->mark_or_rebuild_in_progress()) {
507 return;
508 }
509
510 // Clear any statistics about the region gathered so far.
511 clear_statistics(r);
512 }
513
514 void G1ConcurrentMark::reset_marking_for_restart() {
515 _global_mark_stack.set_empty();
516
517 // Expand the marking stack, if we have to and if we can.
518 if (has_overflown()) {
519 _global_mark_stack.expand();
520
521 uint max_regions = _g1h->max_regions();
522 for (uint i = 0; i < max_regions; i++) {
523 _region_mark_stats[i].clear_during_overflow();
524 }
525 }
526
527 clear_has_overflown();
528 _finger = _heap.start();
529
530 for (uint i = 0; i < _max_num_tasks; ++i) {
531 G1CMTaskQueue* queue = _task_queues->queue(i);
532 queue->set_empty();
533 }
534 }
535
536 void G1ConcurrentMark::set_concurrency(uint active_tasks) {
537 assert(active_tasks <= _max_num_tasks, "we should not have more");
538
539 _num_active_tasks = active_tasks;
540 // Need to update the three data structures below according to the
541 // number of active threads for this phase.
542 _terminator.reset_for_reuse(active_tasks);
543 _first_overflow_barrier_sync.set_n_workers((int) active_tasks);
544 _second_overflow_barrier_sync.set_n_workers((int) active_tasks);
545 }
546
547 void G1ConcurrentMark::set_concurrency_and_phase(uint active_tasks, bool concurrent) {
548 set_concurrency(active_tasks);
549
550 _concurrent = concurrent;
551
552 if (!concurrent) {
553 // At this point we should be in a STW phase, and completed marking.
554 assert_at_safepoint_on_vm_thread();
555 assert(out_of_regions(),
556 "only way to get here: _finger: " PTR_FORMAT ", _heap_end: " PTR_FORMAT,
557 p2i(_finger), p2i(_heap.end()));
558 }
559 }
560
561 void G1ConcurrentMark::reset_at_marking_complete() {
562 // We set the global marking state to some default values when we're
563 // not doing marking.
564 reset_marking_for_restart();
565 _num_active_tasks = 0;
566 }
567
568 G1ConcurrentMark::~G1ConcurrentMark() {
569 FREE_C_HEAP_ARRAY(HeapWord*, _top_at_rebuild_starts);
570 FREE_C_HEAP_ARRAY(G1RegionMarkStats, _region_mark_stats);
571 // The G1ConcurrentMark instance is never freed.
572 ShouldNotReachHere();
573 }
574
575 class G1ClearBitMapTask : public AbstractGangTask {
576 public:
577 static size_t chunk_size() { return M; }
578
579 private:
580 // Heap region closure used for clearing the given mark bitmap.
581 class G1ClearBitmapHRClosure : public HeapRegionClosure {
582 private:
583 G1CMBitMap* _bitmap;
584 G1ConcurrentMark* _cm;
585 public:
586 G1ClearBitmapHRClosure(G1CMBitMap* bitmap, G1ConcurrentMark* cm) : HeapRegionClosure(), _bitmap(bitmap), _cm(cm) {
587 }
588
589 virtual bool do_heap_region(HeapRegion* r) {
590 size_t const chunk_size_in_words = G1ClearBitMapTask::chunk_size() / HeapWordSize;
591
592 HeapWord* cur = r->bottom();
593 HeapWord* const end = r->end();
594
595 while (cur < end) {
596 MemRegion mr(cur, MIN2(cur + chunk_size_in_words, end));
597 _bitmap->clear_range(mr);
598
599 cur += chunk_size_in_words;
600
601 // Abort iteration if after yielding the marking has been aborted.
602 if (_cm != NULL && _cm->do_yield_check() && _cm->has_aborted()) {
603 return true;
604 }
605 // Repeat the asserts from before the start of the closure. We will do them
606 // as asserts here to minimize their overhead on the product. However, we
607 // will have them as guarantees at the beginning / end of the bitmap
608 // clearing to get some checking in the product.
609 assert(_cm == NULL || _cm->cm_thread()->during_cycle(), "invariant");
610 assert(_cm == NULL || !G1CollectedHeap::heap()->collector_state()->mark_or_rebuild_in_progress(), "invariant");
611 }
612 assert(cur == end, "Must have completed iteration over the bitmap for region %u.", r->hrm_index());
613
614 return false;
615 }
616 };
617
618 G1ClearBitmapHRClosure _cl;
619 HeapRegionClaimer _hr_claimer;
620 bool _suspendible; // If the task is suspendible, workers must join the STS.
621
622 public:
623 G1ClearBitMapTask(G1CMBitMap* bitmap, G1ConcurrentMark* cm, uint n_workers, bool suspendible) :
624 AbstractGangTask("G1 Clear Bitmap"),
625 _cl(bitmap, suspendible ? cm : NULL),
626 _hr_claimer(n_workers),
627 _suspendible(suspendible)
628 { }
629
630 void work(uint worker_id) {
631 SuspendibleThreadSetJoiner sts_join(_suspendible);
632 G1CollectedHeap::heap()->heap_region_par_iterate_from_worker_offset(&_cl, &_hr_claimer, worker_id);
633 }
634
635 bool is_complete() {
636 return _cl.is_complete();
637 }
638 };
639
640 void G1ConcurrentMark::clear_bitmap(G1CMBitMap* bitmap, WorkGang* workers, bool may_yield) {
641 assert(may_yield || SafepointSynchronize::is_at_safepoint(), "Non-yielding bitmap clear only allowed at safepoint.");
642
643 size_t const num_bytes_to_clear = (HeapRegion::GrainBytes * _g1h->num_regions()) / G1CMBitMap::heap_map_factor();
644 size_t const num_chunks = align_up(num_bytes_to_clear, G1ClearBitMapTask::chunk_size()) / G1ClearBitMapTask::chunk_size();
645
646 uint const num_workers = (uint)MIN2(num_chunks, (size_t)workers->active_workers());
647
648 G1ClearBitMapTask cl(bitmap, this, num_workers, may_yield);
649
650 log_debug(gc, ergo)("Running %s with %u workers for " SIZE_FORMAT " work units.", cl.name(), num_workers, num_chunks);
651 workers->run_task(&cl, num_workers);
652 guarantee(!may_yield || cl.is_complete(), "Must have completed iteration when not yielding.");
653 }
654
655 void G1ConcurrentMark::cleanup_for_next_mark() {
656 // Make sure that the concurrent mark thread looks to still be in
657 // the current cycle.
658 guarantee(cm_thread()->during_cycle(), "invariant");
659
660 // We are finishing up the current cycle by clearing the next
661 // marking bitmap and getting it ready for the next cycle. During
662 // this time no other cycle can start. So, let's make sure that this
663 // is the case.
664 guarantee(!_g1h->collector_state()->mark_or_rebuild_in_progress(), "invariant");
665
666 clear_bitmap(_next_mark_bitmap, _concurrent_workers, true);
667
668 // Repeat the asserts from above.
669 guarantee(cm_thread()->during_cycle(), "invariant");
670 guarantee(!_g1h->collector_state()->mark_or_rebuild_in_progress(), "invariant");
671 }
672
673 void G1ConcurrentMark::clear_prev_bitmap(WorkGang* workers) {
674 assert_at_safepoint_on_vm_thread();
675 clear_bitmap(_prev_mark_bitmap, workers, false);
676 }
677
678 class NoteStartOfMarkHRClosure : public HeapRegionClosure {
679 public:
680 bool do_heap_region(HeapRegion* r) {
681 r->note_start_of_marking();
682 return false;
683 }
684 };
685
686 void G1ConcurrentMark::pre_concurrent_start() {
687 assert_at_safepoint_on_vm_thread();
688
689 // Reset marking state.
690 reset();
691
692 // For each region note start of marking.
693 NoteStartOfMarkHRClosure startcl;
694 _g1h->heap_region_iterate(&startcl);
695
696 _root_regions.reset();
697 }
698
699
700 void G1ConcurrentMark::post_concurrent_start() {
701 // Start Concurrent Marking weak-reference discovery.
702 ReferenceProcessor* rp = _g1h->ref_processor_cm();
703 // enable ("weak") refs discovery
704 rp->enable_discovery();
705 rp->setup_policy(false); // snapshot the soft ref policy to be used in this cycle
706
707 SATBMarkQueueSet& satb_mq_set = G1BarrierSet::satb_mark_queue_set();
708 // This is the start of the marking cycle, we're expected all
709 // threads to have SATB queues with active set to false.
710 satb_mq_set.set_active_all_threads(true, /* new active value */
711 false /* expected_active */);
712
713 _root_regions.prepare_for_scan();
714
715 // update_g1_committed() will be called at the end of an evac pause
716 // when marking is on. So, it's also called at the end of the
717 // concurrent start pause to update the heap end, if the heap expands
718 // during it. No need to call it here.
719 }
720
721 /*
722 * Notice that in the next two methods, we actually leave the STS
723 * during the barrier sync and join it immediately afterwards. If we
724 * do not do this, the following deadlock can occur: one thread could
725 * be in the barrier sync code, waiting for the other thread to also
726 * sync up, whereas another one could be trying to yield, while also
727 * waiting for the other threads to sync up too.
728 *
729 * Note, however, that this code is also used during remark and in
730 * this case we should not attempt to leave / enter the STS, otherwise
731 * we'll either hit an assert (debug / fastdebug) or deadlock
732 * (product). So we should only leave / enter the STS if we are
733 * operating concurrently.
734 *
735 * Because the thread that does the sync barrier has left the STS, it
736 * is possible to be suspended for a Full GC or an evacuation pause
737 * could occur. This is actually safe, since the entering the sync
738 * barrier is one of the last things do_marking_step() does, and it
739 * doesn't manipulate any data structures afterwards.
740 */
741
742 void G1ConcurrentMark::enter_first_sync_barrier(uint worker_id) {
743 bool barrier_aborted;
744 {
745 SuspendibleThreadSetLeaver sts_leave(concurrent());
746 barrier_aborted = !_first_overflow_barrier_sync.enter();
747 }
748
749 // at this point everyone should have synced up and not be doing any
750 // more work
751
752 if (barrier_aborted) {
753 // If the barrier aborted we ignore the overflow condition and
754 // just abort the whole marking phase as quickly as possible.
755 return;
756 }
757 }
758
759 void G1ConcurrentMark::enter_second_sync_barrier(uint worker_id) {
760 SuspendibleThreadSetLeaver sts_leave(concurrent());
761 _second_overflow_barrier_sync.enter();
762
763 // at this point everything should be re-initialized and ready to go
764 }
765
766 class G1CMConcurrentMarkingTask : public AbstractGangTask {
767 G1ConcurrentMark* _cm;
768
769 public:
770 void work(uint worker_id) {
771 assert(Thread::current()->is_ConcurrentGC_thread(), "Not a concurrent GC thread");
772 ResourceMark rm;
773
774 double start_vtime = os::elapsedVTime();
775
776 {
777 SuspendibleThreadSetJoiner sts_join;
778
779 assert(worker_id < _cm->active_tasks(), "invariant");
780
781 G1CMTask* task = _cm->task(worker_id);
782 task->record_start_time();
783 if (!_cm->has_aborted()) {
784 do {
785 task->do_marking_step(G1ConcMarkStepDurationMillis,
786 true /* do_termination */,
787 false /* is_serial*/);
788
789 _cm->do_yield_check();
790 } while (!_cm->has_aborted() && task->has_aborted());
791 }
792 task->record_end_time();
793 guarantee(!task->has_aborted() || _cm->has_aborted(), "invariant");
794 }
795
796 double end_vtime = os::elapsedVTime();
797 _cm->update_accum_task_vtime(worker_id, end_vtime - start_vtime);
798 }
799
800 G1CMConcurrentMarkingTask(G1ConcurrentMark* cm) :
801 AbstractGangTask("Concurrent Mark"), _cm(cm) { }
802
803 ~G1CMConcurrentMarkingTask() { }
804 };
805
806 uint G1ConcurrentMark::calc_active_marking_workers() {
807 uint result = 0;
808 if (!UseDynamicNumberOfGCThreads || !FLAG_IS_DEFAULT(ConcGCThreads)) {
809 result = _max_concurrent_workers;
810 } else {
811 result =
812 WorkerPolicy::calc_default_active_workers(_max_concurrent_workers,
813 1, /* Minimum workers */
814 _num_concurrent_workers,
815 Threads::number_of_non_daemon_threads());
816 // Don't scale the result down by scale_concurrent_workers() because
817 // that scaling has already gone into "_max_concurrent_workers".
818 }
819 assert(result > 0 && result <= _max_concurrent_workers,
820 "Calculated number of marking workers must be larger than zero and at most the maximum %u, but is %u",
821 _max_concurrent_workers, result);
822 return result;
823 }
824
825 void G1ConcurrentMark::scan_root_region(const MemRegion* region, uint worker_id) {
826 #ifdef ASSERT
827 HeapWord* last = region->last();
828 HeapRegion* hr = _g1h->heap_region_containing(last);
829 assert(hr->is_old() || hr->next_top_at_mark_start() == hr->bottom(),
830 "Root regions must be old or survivor/eden but region %u is %s", hr->hrm_index(), hr->get_type_str());
831 assert(hr->next_top_at_mark_start() == region->start(),
832 "MemRegion start should be equal to nTAMS");
833 #endif
834
835 G1RootRegionScanClosure cl(_g1h, this, worker_id);
836
837 const uintx interval = PrefetchScanIntervalInBytes;
838 HeapWord* curr = region->start();
839 const HeapWord* end = region->end();
840 while (curr < end) {
841 Prefetch::read(curr, interval);
842 oop obj = oop(curr);
843 int size = obj->oop_iterate_size(&cl);
844 assert(size == obj->size(), "sanity");
845 curr += size;
846 }
847 }
848
849 class G1CMRootRegionScanTask : public AbstractGangTask {
850 G1ConcurrentMark* _cm;
851 public:
852 G1CMRootRegionScanTask(G1ConcurrentMark* cm) :
853 AbstractGangTask("G1 Root Region Scan"), _cm(cm) { }
854
855 void work(uint worker_id) {
856 assert(Thread::current()->is_ConcurrentGC_thread(),
857 "this should only be done by a conc GC thread");
858
859 G1CMRootMemRegions* root_regions = _cm->root_regions();
860 const MemRegion* region = root_regions->claim_next();
861 while (region != NULL) {
862 _cm->scan_root_region(region, worker_id);
863 region = root_regions->claim_next();
864 }
865 }
866 };
867
868 void G1ConcurrentMark::scan_root_regions() {
869 // scan_in_progress() will have been set to true only if there was
870 // at least one root region to scan. So, if it's false, we
871 // should not attempt to do any further work.
872 if (root_regions()->scan_in_progress()) {
873 assert(!has_aborted(), "Aborting before root region scanning is finished not supported.");
874
875 _num_concurrent_workers = MIN2(calc_active_marking_workers(),
876 // We distribute work on a per-region basis, so starting
877 // more threads than that is useless.
878 root_regions()->num_root_regions());
879 assert(_num_concurrent_workers <= _max_concurrent_workers,
880 "Maximum number of marking threads exceeded");
881
882 G1CMRootRegionScanTask task(this);
883 log_debug(gc, ergo)("Running %s using %u workers for %u work units.",
884 task.name(), _num_concurrent_workers, root_regions()->num_root_regions());
885 _concurrent_workers->run_task(&task, _num_concurrent_workers);
886
887 // It's possible that has_aborted() is true here without actually
888 // aborting the survivor scan earlier. This is OK as it's
889 // mainly used for sanity checking.
890 root_regions()->scan_finished();
891 }
892 }
893
894 void G1ConcurrentMark::concurrent_cycle_start() {
895 _gc_timer_cm->register_gc_start();
896
897 _gc_tracer_cm->report_gc_start(GCCause::_no_gc /* first parameter is not used */, _gc_timer_cm->gc_start());
898
899 _g1h->trace_heap_before_gc(_gc_tracer_cm);
900 }
901
902 void G1ConcurrentMark::concurrent_cycle_end() {
903 _g1h->collector_state()->set_clearing_next_bitmap(false);
904
905 _g1h->trace_heap_after_gc(_gc_tracer_cm);
906
907 if (has_aborted()) {
908 log_info(gc, marking)("Concurrent Mark Abort");
909 _gc_tracer_cm->report_concurrent_mode_failure();
910 }
911
912 _gc_timer_cm->register_gc_end();
913
914 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
915 }
916
917 void G1ConcurrentMark::mark_from_roots() {
918 _restart_for_overflow = false;
919
920 _num_concurrent_workers = calc_active_marking_workers();
921
922 uint active_workers = MAX2(1U, _num_concurrent_workers);
923
924 // Setting active workers is not guaranteed since fewer
925 // worker threads may currently exist and more may not be
926 // available.
927 active_workers = _concurrent_workers->update_active_workers(active_workers);
928 log_info(gc, task)("Using %u workers of %u for marking", active_workers, _concurrent_workers->total_workers());
929
930 // Parallel task terminator is set in "set_concurrency_and_phase()"
931 set_concurrency_and_phase(active_workers, true /* concurrent */);
932
933 G1CMConcurrentMarkingTask marking_task(this);
934 _concurrent_workers->run_task(&marking_task);
935 print_stats();
936 }
937
938 void G1ConcurrentMark::verify_during_pause(G1HeapVerifier::G1VerifyType type, VerifyOption vo, const char* caller) {
939 G1HeapVerifier* verifier = _g1h->verifier();
940
941 verifier->verify_region_sets_optional();
942
943 if (VerifyDuringGC) {
944 GCTraceTime(Debug, gc, phases) debug(caller, _gc_timer_cm);
945
946 size_t const BufLen = 512;
947 char buffer[BufLen];
948
949 jio_snprintf(buffer, BufLen, "During GC (%s)", caller);
950 verifier->verify(type, vo, buffer);
951 }
952
953 verifier->check_bitmaps(caller);
954 }
955
956 class G1UpdateRemSetTrackingBeforeRebuildTask : public AbstractGangTask {
957 G1CollectedHeap* _g1h;
958 G1ConcurrentMark* _cm;
959 HeapRegionClaimer _hrclaimer;
960 uint volatile _total_selected_for_rebuild;
961
962 G1PrintRegionLivenessInfoClosure _cl;
963
964 class G1UpdateRemSetTrackingBeforeRebuild : public HeapRegionClosure {
965 G1CollectedHeap* _g1h;
966 G1ConcurrentMark* _cm;
967
968 G1PrintRegionLivenessInfoClosure* _cl;
969
970 uint _num_regions_selected_for_rebuild; // The number of regions actually selected for rebuild.
971
972 void update_remset_before_rebuild(HeapRegion* hr) {
973 G1RemSetTrackingPolicy* tracking_policy = _g1h->policy()->remset_tracker();
974
975 bool selected_for_rebuild;
976 if (hr->is_humongous()) {
977 bool const is_live = _cm->liveness(hr->humongous_start_region()->hrm_index()) > 0;
978 selected_for_rebuild = tracking_policy->update_humongous_before_rebuild(hr, is_live);
979 } else {
980 size_t const live_bytes = _cm->liveness(hr->hrm_index());
981 selected_for_rebuild = tracking_policy->update_before_rebuild(hr, live_bytes);
982 }
983 if (selected_for_rebuild) {
984 _num_regions_selected_for_rebuild++;
985 }
986 _cm->update_top_at_rebuild_start(hr);
987 }
988
989 // Distribute the given words across the humongous object starting with hr and
990 // note end of marking.
991 void distribute_marked_bytes(HeapRegion* hr, size_t marked_words) {
992 uint const region_idx = hr->hrm_index();
993 size_t const obj_size_in_words = (size_t)oop(hr->bottom())->size();
994 uint const num_regions_in_humongous = (uint)G1CollectedHeap::humongous_obj_size_in_regions(obj_size_in_words);
995
996 // "Distributing" zero words means that we only note end of marking for these
997 // regions.
998 assert(marked_words == 0 || obj_size_in_words == marked_words,
999 "Marked words should either be 0 or the same as humongous object (" SIZE_FORMAT ") but is " SIZE_FORMAT,
1000 obj_size_in_words, marked_words);
1001
1002 for (uint i = region_idx; i < (region_idx + num_regions_in_humongous); i++) {
1003 HeapRegion* const r = _g1h->region_at(i);
1004 size_t const words_to_add = MIN2(HeapRegion::GrainWords, marked_words);
1005
1006 log_trace(gc, marking)("Adding " SIZE_FORMAT " words to humongous region %u (%s)",
1007 words_to_add, i, r->get_type_str());
1008 add_marked_bytes_and_note_end(r, words_to_add * HeapWordSize);
1009 marked_words -= words_to_add;
1010 }
1011 assert(marked_words == 0,
1012 SIZE_FORMAT " words left after distributing space across %u regions",
1013 marked_words, num_regions_in_humongous);
1014 }
1015
1016 void update_marked_bytes(HeapRegion* hr) {
1017 uint const region_idx = hr->hrm_index();
1018 size_t const marked_words = _cm->liveness(region_idx);
1019 // The marking attributes the object's size completely to the humongous starts
1020 // region. We need to distribute this value across the entire set of regions a
1021 // humongous object spans.
1022 if (hr->is_humongous()) {
1023 assert(hr->is_starts_humongous() || marked_words == 0,
1024 "Should not have marked words " SIZE_FORMAT " in non-starts humongous region %u (%s)",
1025 marked_words, region_idx, hr->get_type_str());
1026 if (hr->is_starts_humongous()) {
1027 distribute_marked_bytes(hr, marked_words);
1028 }
1029 } else {
1030 log_trace(gc, marking)("Adding " SIZE_FORMAT " words to region %u (%s)", marked_words, region_idx, hr->get_type_str());
1031 add_marked_bytes_and_note_end(hr, marked_words * HeapWordSize);
1032 }
1033 }
1034
1035 void add_marked_bytes_and_note_end(HeapRegion* hr, size_t marked_bytes) {
1036 hr->add_to_marked_bytes(marked_bytes);
1037 _cl->do_heap_region(hr);
1038 hr->note_end_of_marking();
1039 }
1040
1041 public:
1042 G1UpdateRemSetTrackingBeforeRebuild(G1CollectedHeap* g1h, G1ConcurrentMark* cm, G1PrintRegionLivenessInfoClosure* cl) :
1043 _g1h(g1h), _cm(cm), _cl(cl), _num_regions_selected_for_rebuild(0) { }
1044
1045 virtual bool do_heap_region(HeapRegion* r) {
1046 update_remset_before_rebuild(r);
1047 update_marked_bytes(r);
1048
1049 return false;
1050 }
1051
1052 uint num_selected_for_rebuild() const { return _num_regions_selected_for_rebuild; }
1053 };
1054
1055 public:
1056 G1UpdateRemSetTrackingBeforeRebuildTask(G1CollectedHeap* g1h, G1ConcurrentMark* cm, uint num_workers) :
1057 AbstractGangTask("G1 Update RemSet Tracking Before Rebuild"),
1058 _g1h(g1h), _cm(cm), _hrclaimer(num_workers), _total_selected_for_rebuild(0), _cl("Post-Marking") { }
1059
1060 virtual void work(uint worker_id) {
1061 G1UpdateRemSetTrackingBeforeRebuild update_cl(_g1h, _cm, &_cl);
1062 _g1h->heap_region_par_iterate_from_worker_offset(&update_cl, &_hrclaimer, worker_id);
1063 Atomic::add(&_total_selected_for_rebuild, update_cl.num_selected_for_rebuild());
1064 }
1065
1066 uint total_selected_for_rebuild() const { return _total_selected_for_rebuild; }
1067
1068 // Number of regions for which roughly one thread should be spawned for this work.
1069 static const uint RegionsPerThread = 384;
1070 };
1071
1072 class G1UpdateRemSetTrackingAfterRebuild : public HeapRegionClosure {
1073 G1CollectedHeap* _g1h;
1074 public:
1075 G1UpdateRemSetTrackingAfterRebuild(G1CollectedHeap* g1h) : _g1h(g1h) { }
1076
1077 virtual bool do_heap_region(HeapRegion* r) {
1078 _g1h->policy()->remset_tracker()->update_after_rebuild(r);
1079 return false;
1080 }
1081 };
1082
1083 void G1ConcurrentMark::remark() {
1084 assert_at_safepoint_on_vm_thread();
1085
1086 // If a full collection has happened, we should not continue. However we might
1087 // have ended up here as the Remark VM operation has been scheduled already.
1088 if (has_aborted()) {
1089 return;
1090 }
1091
1092 G1Policy* policy = _g1h->policy();
1093 policy->record_concurrent_mark_remark_start();
1094
1095 double start = os::elapsedTime();
1096
1097 verify_during_pause(G1HeapVerifier::G1VerifyRemark, VerifyOption_G1UsePrevMarking, "Remark before");
1098
1099 {
1100 GCTraceTime(Debug, gc, phases) debug("Finalize Marking", _gc_timer_cm);
1101 finalize_marking();
1102 }
1103
1104 double mark_work_end = os::elapsedTime();
1105
1106 bool const mark_finished = !has_overflown();
1107 if (mark_finished) {
1108 weak_refs_work(false /* clear_all_soft_refs */);
1109
1110 SATBMarkQueueSet& satb_mq_set = G1BarrierSet::satb_mark_queue_set();
1111 // We're done with marking.
1112 // This is the end of the marking cycle, we're expected all
1113 // threads to have SATB queues with active set to true.
1114 satb_mq_set.set_active_all_threads(false, /* new active value */
1115 true /* expected_active */);
1116
1117 {
1118 GCTraceTime(Debug, gc, phases) debug("Flush Task Caches", _gc_timer_cm);
1119 flush_all_task_caches();
1120 }
1121
1122 // Install newly created mark bitmap as "prev".
1123 swap_mark_bitmaps();
1124 {
1125 GCTraceTime(Debug, gc, phases) debug("Update Remembered Set Tracking Before Rebuild", _gc_timer_cm);
1126
1127 uint const workers_by_capacity = (_g1h->num_regions() + G1UpdateRemSetTrackingBeforeRebuildTask::RegionsPerThread - 1) /
1128 G1UpdateRemSetTrackingBeforeRebuildTask::RegionsPerThread;
1129 uint const num_workers = MIN2(_g1h->workers()->active_workers(), workers_by_capacity);
1130
1131 G1UpdateRemSetTrackingBeforeRebuildTask cl(_g1h, this, num_workers);
1132 log_debug(gc,ergo)("Running %s using %u workers for %u regions in heap", cl.name(), num_workers, _g1h->num_regions());
1133 _g1h->workers()->run_task(&cl, num_workers);
1134
1135 log_debug(gc, remset, tracking)("Remembered Set Tracking update regions total %u, selected %u",
1136 _g1h->num_regions(), cl.total_selected_for_rebuild());
1137 }
1138 {
1139 GCTraceTime(Debug, gc, phases) debug("Reclaim Empty Regions", _gc_timer_cm);
1140 reclaim_empty_regions();
1141 }
1142
1143 // Clean out dead classes
1144 if (ClassUnloadingWithConcurrentMark) {
1145 GCTraceTime(Debug, gc, phases) debug("Purge Metaspace", _gc_timer_cm);
1146 ClassLoaderDataGraph::purge();
1147 }
1148
1149 _g1h->resize_heap_if_necessary();
1150
1151 compute_new_sizes();
1152
1153 verify_during_pause(G1HeapVerifier::G1VerifyRemark, VerifyOption_G1UsePrevMarking, "Remark after");
1154
1155 assert(!restart_for_overflow(), "sanity");
1156 // Completely reset the marking state since marking completed
1157 reset_at_marking_complete();
1158 } else {
1159 // We overflowed. Restart concurrent marking.
1160 _restart_for_overflow = true;
1161
1162 verify_during_pause(G1HeapVerifier::G1VerifyRemark, VerifyOption_G1UsePrevMarking, "Remark overflow");
1163
1164 // Clear the marking state because we will be restarting
1165 // marking due to overflowing the global mark stack.
1166 reset_marking_for_restart();
1167 }
1168
1169 {
1170 GCTraceTime(Debug, gc, phases) debug("Report Object Count", _gc_timer_cm);
1171 report_object_count(mark_finished);
1172 }
1173
1174 // Statistics
1175 double now = os::elapsedTime();
1176 _remark_mark_times.add((mark_work_end - start) * 1000.0);
1177 _remark_weak_ref_times.add((now - mark_work_end) * 1000.0);
1178 _remark_times.add((now - start) * 1000.0);
1179
1180 policy->record_concurrent_mark_remark_end();
1181 }
1182
1183 class G1ReclaimEmptyRegionsTask : public AbstractGangTask {
1184 // Per-region work during the Cleanup pause.
1185 class G1ReclaimEmptyRegionsClosure : public HeapRegionClosure {
1186 G1CollectedHeap* _g1h;
1187 size_t _freed_bytes;
1188 FreeRegionList* _local_cleanup_list;
1189 uint _old_regions_removed;
1190 uint _humongous_regions_removed;
1191
1192 public:
1193 G1ReclaimEmptyRegionsClosure(G1CollectedHeap* g1h,
1194 FreeRegionList* local_cleanup_list) :
1195 _g1h(g1h),
1196 _freed_bytes(0),
1197 _local_cleanup_list(local_cleanup_list),
1198 _old_regions_removed(0),
1199 _humongous_regions_removed(0) { }
1200
1201 size_t freed_bytes() { return _freed_bytes; }
1202 const uint old_regions_removed() { return _old_regions_removed; }
1203 const uint humongous_regions_removed() { return _humongous_regions_removed; }
1204
1205 bool do_heap_region(HeapRegion *hr) {
1206 if (hr->used() > 0 && hr->max_live_bytes() == 0 && !hr->is_young() && !hr->is_archive()) {
1207 _freed_bytes += hr->used();
1208 hr->set_containing_set(NULL);
1209 if (hr->is_humongous()) {
1210 _humongous_regions_removed++;
1211 _g1h->free_humongous_region(hr, _local_cleanup_list);
1212 } else {
1213 _old_regions_removed++;
1214 _g1h->free_region(hr, _local_cleanup_list);
1215 }
1216 hr->clear_cardtable();
1217 _g1h->concurrent_mark()->clear_statistics_in_region(hr->hrm_index());
1218 log_trace(gc)("Reclaimed empty region %u (%s) bot " PTR_FORMAT, hr->hrm_index(), hr->get_short_type_str(), p2i(hr->bottom()));
1219 }
1220
1221 return false;
1222 }
1223 };
1224
1225 G1CollectedHeap* _g1h;
1226 FreeRegionList* _cleanup_list;
1227 HeapRegionClaimer _hrclaimer;
1228
1229 public:
1230 G1ReclaimEmptyRegionsTask(G1CollectedHeap* g1h, FreeRegionList* cleanup_list, uint n_workers) :
1231 AbstractGangTask("G1 Cleanup"),
1232 _g1h(g1h),
1233 _cleanup_list(cleanup_list),
1234 _hrclaimer(n_workers) {
1235 }
1236
1237 void work(uint worker_id) {
1238 FreeRegionList local_cleanup_list("Local Cleanup List");
1239 G1ReclaimEmptyRegionsClosure cl(_g1h, &local_cleanup_list);
1240 _g1h->heap_region_par_iterate_from_worker_offset(&cl, &_hrclaimer, worker_id);
1241 assert(cl.is_complete(), "Shouldn't have aborted!");
1242
1243 // Now update the old/humongous region sets
1244 _g1h->remove_from_old_sets(cl.old_regions_removed(), cl.humongous_regions_removed());
1245 {
1246 MutexLocker x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
1247 _g1h->decrement_summary_bytes(cl.freed_bytes());
1248
1249 _cleanup_list->add_ordered(&local_cleanup_list);
1250 assert(local_cleanup_list.is_empty(), "post-condition");
1251 }
1252 }
1253 };
1254
1255 void G1ConcurrentMark::reclaim_empty_regions() {
1256 WorkGang* workers = _g1h->workers();
1257 FreeRegionList empty_regions_list("Empty Regions After Mark List");
1258
1259 G1ReclaimEmptyRegionsTask cl(_g1h, &empty_regions_list, workers->active_workers());
1260 workers->run_task(&cl);
1261
1262 if (!empty_regions_list.is_empty()) {
1263 log_debug(gc)("Reclaimed %u empty regions", empty_regions_list.length());
1264 // Now print the empty regions list.
1265 G1HRPrinter* hrp = _g1h->hr_printer();
1266 if (hrp->is_active()) {
1267 FreeRegionListIterator iter(&empty_regions_list);
1268 while (iter.more_available()) {
1269 HeapRegion* hr = iter.get_next();
1270 hrp->cleanup(hr);
1271 }
1272 }
1273 // And actually make them available.
1274 _g1h->prepend_to_freelist(&empty_regions_list);
1275 }
1276 }
1277
1278 void G1ConcurrentMark::compute_new_sizes() {
1279 MetaspaceGC::compute_new_size();
1280
1281 // Cleanup will have freed any regions completely full of garbage.
1282 // Update the soft reference policy with the new heap occupancy.
1283 Universe::update_heap_info_at_gc();
1284
1285 // We reclaimed old regions so we should calculate the sizes to make
1286 // sure we update the old gen/space data.
1287 _g1h->g1mm()->update_sizes();
1288 }
1289
1290 void G1ConcurrentMark::cleanup() {
1291 assert_at_safepoint_on_vm_thread();
1292
1293 // If a full collection has happened, we shouldn't do this.
1294 if (has_aborted()) {
1295 return;
1296 }
1297
1298 G1Policy* policy = _g1h->policy();
1299 policy->record_concurrent_mark_cleanup_start();
1300
1301 double start = os::elapsedTime();
1302
1303 verify_during_pause(G1HeapVerifier::G1VerifyCleanup, VerifyOption_G1UsePrevMarking, "Cleanup before");
1304
1305 {
1306 GCTraceTime(Debug, gc, phases) debug("Update Remembered Set Tracking After Rebuild", _gc_timer_cm);
1307 G1UpdateRemSetTrackingAfterRebuild cl(_g1h);
1308 _g1h->heap_region_iterate(&cl);
1309 }
1310
1311 if (log_is_enabled(Trace, gc, liveness)) {
1312 G1PrintRegionLivenessInfoClosure cl("Post-Cleanup");
1313 _g1h->heap_region_iterate(&cl);
1314 }
1315
1316 verify_during_pause(G1HeapVerifier::G1VerifyCleanup, VerifyOption_G1UsePrevMarking, "Cleanup after");
1317
1318 // We need to make this be a "collection" so any collection pause that
1319 // races with it goes around and waits for Cleanup to finish.
1320 _g1h->increment_total_collections();
1321
1322 // Local statistics
1323 double recent_cleanup_time = (os::elapsedTime() - start);
1324 _total_cleanup_time += recent_cleanup_time;
1325 _cleanup_times.add(recent_cleanup_time);
1326
1327 {
1328 GCTraceTime(Debug, gc, phases) debug("Finalize Concurrent Mark Cleanup", _gc_timer_cm);
1329 policy->record_concurrent_mark_cleanup_end();
1330 }
1331 }
1332
1333 // 'Keep Alive' oop closure used by both serial parallel reference processing.
1334 // Uses the G1CMTask associated with a worker thread (for serial reference
1335 // processing the G1CMTask for worker 0 is used) to preserve (mark) and
1336 // trace referent objects.
1337 //
1338 // Using the G1CMTask and embedded local queues avoids having the worker
1339 // threads operating on the global mark stack. This reduces the risk
1340 // of overflowing the stack - which we would rather avoid at this late
1341 // state. Also using the tasks' local queues removes the potential
1342 // of the workers interfering with each other that could occur if
1343 // operating on the global stack.
1344
1345 class G1CMKeepAliveAndDrainClosure : public OopClosure {
1346 G1ConcurrentMark* _cm;
1347 G1CMTask* _task;
1348 uint _ref_counter_limit;
1349 uint _ref_counter;
1350 bool _is_serial;
1351 public:
1352 G1CMKeepAliveAndDrainClosure(G1ConcurrentMark* cm, G1CMTask* task, bool is_serial) :
1353 _cm(cm), _task(task), _ref_counter_limit(G1RefProcDrainInterval),
1354 _ref_counter(_ref_counter_limit), _is_serial(is_serial) {
1355 assert(!_is_serial || _task->worker_id() == 0, "only task 0 for serial code");
1356 }
1357
1358 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
1359 virtual void do_oop( oop* p) { do_oop_work(p); }
1360
1361 template <class T> void do_oop_work(T* p) {
1362 if (_cm->has_overflown()) {
1363 return;
1364 }
1365 if (!_task->deal_with_reference(p)) {
1366 // We did not add anything to the mark bitmap (or mark stack), so there is
1367 // no point trying to drain it.
1368 return;
1369 }
1370 _ref_counter--;
1371
1372 if (_ref_counter == 0) {
1373 // We have dealt with _ref_counter_limit references, pushing them
1374 // and objects reachable from them on to the local stack (and
1375 // possibly the global stack). Call G1CMTask::do_marking_step() to
1376 // process these entries.
1377 //
1378 // We call G1CMTask::do_marking_step() in a loop, which we'll exit if
1379 // there's nothing more to do (i.e. we're done with the entries that
1380 // were pushed as a result of the G1CMTask::deal_with_reference() calls
1381 // above) or we overflow.
1382 //
1383 // Note: G1CMTask::do_marking_step() can set the G1CMTask::has_aborted()
1384 // flag while there may still be some work to do. (See the comment at
1385 // the beginning of G1CMTask::do_marking_step() for those conditions -
1386 // one of which is reaching the specified time target.) It is only
1387 // when G1CMTask::do_marking_step() returns without setting the
1388 // has_aborted() flag that the marking step has completed.
1389 do {
1390 double mark_step_duration_ms = G1ConcMarkStepDurationMillis;
1391 _task->do_marking_step(mark_step_duration_ms,
1392 false /* do_termination */,
1393 _is_serial);
1394 } while (_task->has_aborted() && !_cm->has_overflown());
1395 _ref_counter = _ref_counter_limit;
1396 }
1397 }
1398 };
1399
1400 // 'Drain' oop closure used by both serial and parallel reference processing.
1401 // Uses the G1CMTask associated with a given worker thread (for serial
1402 // reference processing the G1CMtask for worker 0 is used). Calls the
1403 // do_marking_step routine, with an unbelievably large timeout value,
1404 // to drain the marking data structures of the remaining entries
1405 // added by the 'keep alive' oop closure above.
1406
1407 class G1CMDrainMarkingStackClosure : public VoidClosure {
1408 G1ConcurrentMark* _cm;
1409 G1CMTask* _task;
1410 bool _is_serial;
1411 public:
1412 G1CMDrainMarkingStackClosure(G1ConcurrentMark* cm, G1CMTask* task, bool is_serial) :
1413 _cm(cm), _task(task), _is_serial(is_serial) {
1414 assert(!_is_serial || _task->worker_id() == 0, "only task 0 for serial code");
1415 }
1416
1417 void do_void() {
1418 do {
1419 // We call G1CMTask::do_marking_step() to completely drain the local
1420 // and global marking stacks of entries pushed by the 'keep alive'
1421 // oop closure (an instance of G1CMKeepAliveAndDrainClosure above).
1422 //
1423 // G1CMTask::do_marking_step() is called in a loop, which we'll exit
1424 // if there's nothing more to do (i.e. we've completely drained the
1425 // entries that were pushed as a a result of applying the 'keep alive'
1426 // closure to the entries on the discovered ref lists) or we overflow
1427 // the global marking stack.
1428 //
1429 // Note: G1CMTask::do_marking_step() can set the G1CMTask::has_aborted()
1430 // flag while there may still be some work to do. (See the comment at
1431 // the beginning of G1CMTask::do_marking_step() for those conditions -
1432 // one of which is reaching the specified time target.) It is only
1433 // when G1CMTask::do_marking_step() returns without setting the
1434 // has_aborted() flag that the marking step has completed.
1435
1436 _task->do_marking_step(1000000000.0 /* something very large */,
1437 true /* do_termination */,
1438 _is_serial);
1439 } while (_task->has_aborted() && !_cm->has_overflown());
1440 }
1441 };
1442
1443 // Implementation of AbstractRefProcTaskExecutor for parallel
1444 // reference processing at the end of G1 concurrent marking
1445
1446 class G1CMRefProcTaskExecutor : public AbstractRefProcTaskExecutor {
1447 private:
1448 G1CollectedHeap* _g1h;
1449 G1ConcurrentMark* _cm;
1450 WorkGang* _workers;
1451 uint _active_workers;
1452
1453 public:
1454 G1CMRefProcTaskExecutor(G1CollectedHeap* g1h,
1455 G1ConcurrentMark* cm,
1456 WorkGang* workers,
1457 uint n_workers) :
1458 _g1h(g1h), _cm(cm),
1459 _workers(workers), _active_workers(n_workers) { }
1460
1461 virtual void execute(ProcessTask& task, uint ergo_workers);
1462 };
1463
1464 class G1CMRefProcTaskProxy : public AbstractGangTask {
1465 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
1466 ProcessTask& _proc_task;
1467 G1CollectedHeap* _g1h;
1468 G1ConcurrentMark* _cm;
1469
1470 public:
1471 G1CMRefProcTaskProxy(ProcessTask& proc_task,
1472 G1CollectedHeap* g1h,
1473 G1ConcurrentMark* cm) :
1474 AbstractGangTask("Process reference objects in parallel"),
1475 _proc_task(proc_task), _g1h(g1h), _cm(cm) {
1476 ReferenceProcessor* rp = _g1h->ref_processor_cm();
1477 assert(rp->processing_is_mt(), "shouldn't be here otherwise");
1478 }
1479
1480 virtual void work(uint worker_id) {
1481 ResourceMark rm;
1482 G1CMTask* task = _cm->task(worker_id);
1483 G1CMIsAliveClosure g1_is_alive(_g1h);
1484 G1CMKeepAliveAndDrainClosure g1_par_keep_alive(_cm, task, false /* is_serial */);
1485 G1CMDrainMarkingStackClosure g1_par_drain(_cm, task, false /* is_serial */);
1486
1487 _proc_task.work(worker_id, g1_is_alive, g1_par_keep_alive, g1_par_drain);
1488 }
1489 };
1490
1491 void G1CMRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) {
1492 assert(_workers != NULL, "Need parallel worker threads.");
1493 assert(_g1h->ref_processor_cm()->processing_is_mt(), "processing is not MT");
1494 assert(_workers->active_workers() >= ergo_workers,
1495 "Ergonomically chosen workers(%u) should be less than or equal to active workers(%u)",
1496 ergo_workers, _workers->active_workers());
1497
1498 G1CMRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _cm);
1499
1500 // We need to reset the concurrency level before each
1501 // proxy task execution, so that the termination protocol
1502 // and overflow handling in G1CMTask::do_marking_step() knows
1503 // how many workers to wait for.
1504 _cm->set_concurrency(ergo_workers);
1505 _workers->run_task(&proc_task_proxy, ergo_workers);
1506 }
1507
1508 void G1ConcurrentMark::weak_refs_work(bool clear_all_soft_refs) {
1509 ResourceMark rm;
1510
1511 // Is alive closure.
1512 G1CMIsAliveClosure g1_is_alive(_g1h);
1513
1514 // Inner scope to exclude the cleaning of the string table
1515 // from the displayed time.
1516 {
1517 GCTraceTime(Debug, gc, phases) debug("Reference Processing", _gc_timer_cm);
1518
1519 ReferenceProcessor* rp = _g1h->ref_processor_cm();
1520
1521 // See the comment in G1CollectedHeap::ref_processing_init()
1522 // about how reference processing currently works in G1.
1523
1524 // Set the soft reference policy
1525 rp->setup_policy(clear_all_soft_refs);
1526 assert(_global_mark_stack.is_empty(), "mark stack should be empty");
1527
1528 // Instances of the 'Keep Alive' and 'Complete GC' closures used
1529 // in serial reference processing. Note these closures are also
1530 // used for serially processing (by the the current thread) the
1531 // JNI references during parallel reference processing.
1532 //
1533 // These closures do not need to synchronize with the worker
1534 // threads involved in parallel reference processing as these
1535 // instances are executed serially by the current thread (e.g.
1536 // reference processing is not multi-threaded and is thus
1537 // performed by the current thread instead of a gang worker).
1538 //
1539 // The gang tasks involved in parallel reference processing create
1540 // their own instances of these closures, which do their own
1541 // synchronization among themselves.
1542 G1CMKeepAliveAndDrainClosure g1_keep_alive(this, task(0), true /* is_serial */);
1543 G1CMDrainMarkingStackClosure g1_drain_mark_stack(this, task(0), true /* is_serial */);
1544
1545 // We need at least one active thread. If reference processing
1546 // is not multi-threaded we use the current (VMThread) thread,
1547 // otherwise we use the work gang from the G1CollectedHeap and
1548 // we utilize all the worker threads we can.
1549 bool processing_is_mt = rp->processing_is_mt();
1550 uint active_workers = (processing_is_mt ? _g1h->workers()->active_workers() : 1U);
1551 active_workers = clamp(active_workers, 1u, _max_num_tasks);
1552
1553 // Parallel processing task executor.
1554 G1CMRefProcTaskExecutor par_task_executor(_g1h, this,
1555 _g1h->workers(), active_workers);
1556 AbstractRefProcTaskExecutor* executor = (processing_is_mt ? &par_task_executor : NULL);
1557
1558 // Set the concurrency level. The phase was already set prior to
1559 // executing the remark task.
1560 set_concurrency(active_workers);
1561
1562 // Set the degree of MT processing here. If the discovery was done MT,
1563 // the number of threads involved during discovery could differ from
1564 // the number of active workers. This is OK as long as the discovered
1565 // Reference lists are balanced (see balance_all_queues() and balance_queues()).
1566 rp->set_active_mt_degree(active_workers);
1567
1568 ReferenceProcessorPhaseTimes pt(_gc_timer_cm, rp->max_num_queues());
1569
1570 // Process the weak references.
1571 const ReferenceProcessorStats& stats =
1572 rp->process_discovered_references(&g1_is_alive,
1573 &g1_keep_alive,
1574 &g1_drain_mark_stack,
1575 executor,
1576 &pt);
1577 _gc_tracer_cm->report_gc_reference_stats(stats);
1578 pt.print_all_references();
1579
1580 // The do_oop work routines of the keep_alive and drain_marking_stack
1581 // oop closures will set the has_overflown flag if we overflow the
1582 // global marking stack.
1583
1584 assert(has_overflown() || _global_mark_stack.is_empty(),
1585 "Mark stack should be empty (unless it has overflown)");
1586
1587 assert(rp->num_queues() == active_workers, "why not");
1588
1589 rp->verify_no_references_recorded();
1590 assert(!rp->discovery_enabled(), "Post condition");
1591 }
1592
1593 if (has_overflown()) {
1594 // We can not trust g1_is_alive and the contents of the heap if the marking stack
1595 // overflowed while processing references. Exit the VM.
1596 fatal("Overflow during reference processing, can not continue. Please "
1597 "increase MarkStackSizeMax (current value: " SIZE_FORMAT ") and "
1598 "restart.", MarkStackSizeMax);
1599 return;
1600 }
1601
1602 assert(_global_mark_stack.is_empty(), "Marking should have completed");
1603
1604 {
1605 GCTraceTime(Debug, gc, phases) debug("Weak Processing", _gc_timer_cm);
1606 WeakProcessor::weak_oops_do(_g1h->workers(), &g1_is_alive, &do_nothing_cl, 1);
1607 }
1608
1609 // Unload Klasses, String, Code Cache, etc.
1610 if (ClassUnloadingWithConcurrentMark) {
1611 GCTraceTime(Debug, gc, phases) debug("Class Unloading", _gc_timer_cm);
1612 bool purged_classes = SystemDictionary::do_unloading(_gc_timer_cm);
1613 _g1h->complete_cleaning(&g1_is_alive, purged_classes);
1614 } else if (StringDedup::is_enabled()) {
1615 GCTraceTime(Debug, gc, phases) debug("String Deduplication", _gc_timer_cm);
1616 _g1h->string_dedup_cleaning(&g1_is_alive, NULL);
1617 }
1618 }
1619
1620 class G1PrecleanYieldClosure : public YieldClosure {
1621 G1ConcurrentMark* _cm;
1622
1623 public:
1624 G1PrecleanYieldClosure(G1ConcurrentMark* cm) : _cm(cm) { }
1625
1626 virtual bool should_return() {
1627 return _cm->has_aborted();
1628 }
1629
1630 virtual bool should_return_fine_grain() {
1631 _cm->do_yield_check();
1632 return _cm->has_aborted();
1633 }
1634 };
1635
1636 void G1ConcurrentMark::preclean() {
1637 assert(G1UseReferencePrecleaning, "Precleaning must be enabled.");
1638
1639 SuspendibleThreadSetJoiner joiner;
1640
1641 G1CMKeepAliveAndDrainClosure keep_alive(this, task(0), true /* is_serial */);
1642 G1CMDrainMarkingStackClosure drain_mark_stack(this, task(0), true /* is_serial */);
1643
1644 set_concurrency_and_phase(1, true);
1645
1646 G1PrecleanYieldClosure yield_cl(this);
1647
1648 ReferenceProcessor* rp = _g1h->ref_processor_cm();
1649 // Precleaning is single threaded. Temporarily disable MT discovery.
1650 ReferenceProcessorMTDiscoveryMutator rp_mut_discovery(rp, false);
1651 rp->preclean_discovered_references(rp->is_alive_non_header(),
1652 &keep_alive,
1653 &drain_mark_stack,
1654 &yield_cl,
1655 _gc_timer_cm);
1656 }
1657
1658 // When sampling object counts, we already swapped the mark bitmaps, so we need to use
1659 // the prev bitmap determining liveness.
1660 class G1ObjectCountIsAliveClosure: public BoolObjectClosure {
1661 G1CollectedHeap* _g1h;
1662 public:
1663 G1ObjectCountIsAliveClosure(G1CollectedHeap* g1h) : _g1h(g1h) { }
1664
1665 bool do_object_b(oop obj) {
1666 return obj != NULL &&
1667 (!_g1h->is_in_g1_reserved(obj) || !_g1h->is_obj_dead(obj));
1668 }
1669 };
1670
1671 void G1ConcurrentMark::report_object_count(bool mark_completed) {
1672 // Depending on the completion of the marking liveness needs to be determined
1673 // using either the next or prev bitmap.
1674 if (mark_completed) {
1675 G1ObjectCountIsAliveClosure is_alive(_g1h);
1676 _gc_tracer_cm->report_object_count_after_gc(&is_alive);
1677 } else {
1678 G1CMIsAliveClosure is_alive(_g1h);
1679 _gc_tracer_cm->report_object_count_after_gc(&is_alive);
1680 }
1681 }
1682
1683
1684 void G1ConcurrentMark::swap_mark_bitmaps() {
1685 G1CMBitMap* temp = _prev_mark_bitmap;
1686 _prev_mark_bitmap = _next_mark_bitmap;
1687 _next_mark_bitmap = temp;
1688 _g1h->collector_state()->set_clearing_next_bitmap(true);
1689 }
1690
1691 // Closure for marking entries in SATB buffers.
1692 class G1CMSATBBufferClosure : public SATBBufferClosure {
1693 private:
1694 G1CMTask* _task;
1695 G1CollectedHeap* _g1h;
1696
1697 // This is very similar to G1CMTask::deal_with_reference, but with
1698 // more relaxed requirements for the argument, so this must be more
1699 // circumspect about treating the argument as an object.
1700 void do_entry(void* entry) const {
1701 _task->increment_refs_reached();
1702 oop const obj = static_cast<oop>(entry);
1703 _task->make_reference_grey(obj);
1704 }
1705
1706 public:
1707 G1CMSATBBufferClosure(G1CMTask* task, G1CollectedHeap* g1h)
1708 : _task(task), _g1h(g1h) { }
1709
1710 virtual void do_buffer(void** buffer, size_t size) {
1711 for (size_t i = 0; i < size; ++i) {
1712 do_entry(buffer[i]);
1713 }
1714 }
1715 };
1716
1717 class G1RemarkThreadsClosure : public ThreadClosure {
1718 G1CMSATBBufferClosure _cm_satb_cl;
1719 G1CMOopClosure _cm_cl;
1720 MarkingCodeBlobClosure _code_cl;
1721 uintx _claim_token;
1722
1723 public:
1724 G1RemarkThreadsClosure(G1CollectedHeap* g1h, G1CMTask* task) :
1725 _cm_satb_cl(task, g1h),
1726 _cm_cl(g1h, task),
1727 _code_cl(&_cm_cl, !CodeBlobToOopClosure::FixRelocations),
1728 _claim_token(Threads::thread_claim_token()) {}
1729
1730 void do_thread(Thread* thread) {
1731 if (thread->claim_threads_do(true, _claim_token)) {
1732 SATBMarkQueue& queue = G1ThreadLocalData::satb_mark_queue(thread);
1733 queue.apply_closure_and_empty(&_cm_satb_cl);
1734 if (thread->is_Java_thread()) {
1735 // In theory it should not be neccessary to explicitly walk the nmethods to find roots for concurrent marking
1736 // however the liveness of oops reachable from nmethods have very complex lifecycles:
1737 // * Alive if on the stack of an executing method
1738 // * Weakly reachable otherwise
1739 // Some objects reachable from nmethods, such as the class loader (or klass_holder) of the receiver should be
1740 // live by the SATB invariant but other oops recorded in nmethods may behave differently.
1741 JavaThread* jt = (JavaThread*)thread;
1742 jt->nmethods_do(&_code_cl);
1743 }
1744 }
1745 }
1746 };
1747
1748 class G1CMRemarkTask : public AbstractGangTask {
1749 G1ConcurrentMark* _cm;
1750 public:
1751 void work(uint worker_id) {
1752 G1CMTask* task = _cm->task(worker_id);
1753 task->record_start_time();
1754 {
1755 ResourceMark rm;
1756
1757 G1RemarkThreadsClosure threads_f(G1CollectedHeap::heap(), task);
1758 Threads::threads_do(&threads_f);
1759 }
1760
1761 do {
1762 task->do_marking_step(1000000000.0 /* something very large */,
1763 true /* do_termination */,
1764 false /* is_serial */);
1765 } while (task->has_aborted() && !_cm->has_overflown());
1766 // If we overflow, then we do not want to restart. We instead
1767 // want to abort remark and do concurrent marking again.
1768 task->record_end_time();
1769 }
1770
1771 G1CMRemarkTask(G1ConcurrentMark* cm, uint active_workers) :
1772 AbstractGangTask("Par Remark"), _cm(cm) {
1773 _cm->terminator()->reset_for_reuse(active_workers);
1774 }
1775 };
1776
1777 void G1ConcurrentMark::finalize_marking() {
1778 ResourceMark rm;
1779
1780 _g1h->ensure_parsability(false);
1781
1782 // this is remark, so we'll use up all active threads
1783 uint active_workers = _g1h->workers()->active_workers();
1784 set_concurrency_and_phase(active_workers, false /* concurrent */);
1785 // Leave _parallel_marking_threads at it's
1786 // value originally calculated in the G1ConcurrentMark
1787 // constructor and pass values of the active workers
1788 // through the gang in the task.
1789
1790 {
1791 StrongRootsScope srs(active_workers);
1792
1793 G1CMRemarkTask remarkTask(this, active_workers);
1794 // We will start all available threads, even if we decide that the
1795 // active_workers will be fewer. The extra ones will just bail out
1796 // immediately.
1797 _g1h->workers()->run_task(&remarkTask);
1798 }
1799
1800 SATBMarkQueueSet& satb_mq_set = G1BarrierSet::satb_mark_queue_set();
1801 guarantee(has_overflown() ||
1802 satb_mq_set.completed_buffers_num() == 0,
1803 "Invariant: has_overflown = %s, num buffers = " SIZE_FORMAT,
1804 BOOL_TO_STR(has_overflown()),
1805 satb_mq_set.completed_buffers_num());
1806
1807 print_stats();
1808 }
1809
1810 void G1ConcurrentMark::flush_all_task_caches() {
1811 size_t hits = 0;
1812 size_t misses = 0;
1813 for (uint i = 0; i < _max_num_tasks; i++) {
1814 Pair<size_t, size_t> stats = _tasks[i]->flush_mark_stats_cache();
1815 hits += stats.first;
1816 misses += stats.second;
1817 }
1818 size_t sum = hits + misses;
1819 log_debug(gc, stats)("Mark stats cache hits " SIZE_FORMAT " misses " SIZE_FORMAT " ratio %1.3lf",
1820 hits, misses, percent_of(hits, sum));
1821 }
1822
1823 void G1ConcurrentMark::clear_range_in_prev_bitmap(MemRegion mr) {
1824 _prev_mark_bitmap->clear_range(mr);
1825 }
1826
1827 HeapRegion*
1828 G1ConcurrentMark::claim_region(uint worker_id) {
1829 // "checkpoint" the finger
1830 HeapWord* finger = _finger;
1831
1832 while (finger < _heap.end()) {
1833 assert(_g1h->is_in_g1_reserved(finger), "invariant");
1834
1835 HeapRegion* curr_region = _g1h->heap_region_containing(finger);
1836 // Make sure that the reads below do not float before loading curr_region.
1837 OrderAccess::loadload();
1838 // Above heap_region_containing may return NULL as we always scan claim
1839 // until the end of the heap. In this case, just jump to the next region.
1840 HeapWord* end = curr_region != NULL ? curr_region->end() : finger + HeapRegion::GrainWords;
1841
1842 // Is the gap between reading the finger and doing the CAS too long?
1843 HeapWord* res = Atomic::cmpxchg(&_finger, finger, end);
1844 if (res == finger && curr_region != NULL) {
1845 // we succeeded
1846 HeapWord* bottom = curr_region->bottom();
1847 HeapWord* limit = curr_region->next_top_at_mark_start();
1848
1849 // notice that _finger == end cannot be guaranteed here since,
1850 // someone else might have moved the finger even further
1851 assert(_finger >= end, "the finger should have moved forward");
1852
1853 if (limit > bottom) {
1854 return curr_region;
1855 } else {
1856 assert(limit == bottom,
1857 "the region limit should be at bottom");
1858 // we return NULL and the caller should try calling
1859 // claim_region() again.
1860 return NULL;
1861 }
1862 } else {
1863 assert(_finger > finger, "the finger should have moved forward");
1864 // read it again
1865 finger = _finger;
1866 }
1867 }
1868
1869 return NULL;
1870 }
1871
1872 #ifndef PRODUCT
1873 class VerifyNoCSetOops {
1874 G1CollectedHeap* _g1h;
1875 const char* _phase;
1876 int _info;
1877
1878 public:
1879 VerifyNoCSetOops(const char* phase, int info = -1) :
1880 _g1h(G1CollectedHeap::heap()),
1881 _phase(phase),
1882 _info(info)
1883 { }
1884
1885 void operator()(G1TaskQueueEntry task_entry) const {
1886 if (task_entry.is_array_slice()) {
1887 guarantee(_g1h->is_in_reserved(task_entry.slice()), "Slice " PTR_FORMAT " must be in heap.", p2i(task_entry.slice()));
1888 return;
1889 }
1890 guarantee(oopDesc::is_oop(task_entry.obj()),
1891 "Non-oop " PTR_FORMAT ", phase: %s, info: %d",
1892 p2i(task_entry.obj()), _phase, _info);
1893 HeapRegion* r = _g1h->heap_region_containing(task_entry.obj());
1894 guarantee(!(r->in_collection_set() || r->has_index_in_opt_cset()),
1895 "obj " PTR_FORMAT " from %s (%d) in region %u in (optional) collection set",
1896 p2i(task_entry.obj()), _phase, _info, r->hrm_index());
1897 }
1898 };
1899
1900 void G1ConcurrentMark::verify_no_collection_set_oops() {
1901 assert(SafepointSynchronize::is_at_safepoint(), "should be at a safepoint");
1902 if (!_g1h->collector_state()->mark_or_rebuild_in_progress()) {
1903 return;
1904 }
1905
1906 // Verify entries on the global mark stack
1907 _global_mark_stack.iterate(VerifyNoCSetOops("Stack"));
1908
1909 // Verify entries on the task queues
1910 for (uint i = 0; i < _max_num_tasks; ++i) {
1911 G1CMTaskQueue* queue = _task_queues->queue(i);
1912 queue->iterate(VerifyNoCSetOops("Queue", i));
1913 }
1914
1915 // Verify the global finger
1916 HeapWord* global_finger = finger();
1917 if (global_finger != NULL && global_finger < _heap.end()) {
1918 // Since we always iterate over all regions, we might get a NULL HeapRegion
1919 // here.
1920 HeapRegion* global_hr = _g1h->heap_region_containing(global_finger);
1921 guarantee(global_hr == NULL || global_finger == global_hr->bottom(),
1922 "global finger: " PTR_FORMAT " region: " HR_FORMAT,
1923 p2i(global_finger), HR_FORMAT_PARAMS(global_hr));
1924 }
1925
1926 // Verify the task fingers
1927 assert(_num_concurrent_workers <= _max_num_tasks, "sanity");
1928 for (uint i = 0; i < _num_concurrent_workers; ++i) {
1929 G1CMTask* task = _tasks[i];
1930 HeapWord* task_finger = task->finger();
1931 if (task_finger != NULL && task_finger < _heap.end()) {
1932 // See above note on the global finger verification.
1933 HeapRegion* r = _g1h->heap_region_containing(task_finger);
1934 guarantee(r == NULL || task_finger == r->bottom() ||
1935 !r->in_collection_set() || !r->has_index_in_opt_cset(),
1936 "task finger: " PTR_FORMAT " region: " HR_FORMAT,
1937 p2i(task_finger), HR_FORMAT_PARAMS(r));
1938 }
1939 }
1940 }
1941 #endif // PRODUCT
1942
1943 void G1ConcurrentMark::rebuild_rem_set_concurrently() {
1944 _g1h->rem_set()->rebuild_rem_set(this, _concurrent_workers, _worker_id_offset);
1945 }
1946
1947 void G1ConcurrentMark::print_stats() {
1948 if (!log_is_enabled(Debug, gc, stats)) {
1949 return;
1950 }
1951 log_debug(gc, stats)("---------------------------------------------------------------------");
1952 for (size_t i = 0; i < _num_active_tasks; ++i) {
1953 _tasks[i]->print_stats();
1954 log_debug(gc, stats)("---------------------------------------------------------------------");
1955 }
1956 }
1957
1958 void G1ConcurrentMark::concurrent_cycle_abort() {
1959 if (!cm_thread()->during_cycle() || _has_aborted) {
1960 // We haven't started a concurrent cycle or we have already aborted it. No need to do anything.
1961 return;
1962 }
1963
1964 // Clear all marks in the next bitmap for the next marking cycle. This will allow us to skip the next
1965 // concurrent bitmap clearing.
1966 {
1967 GCTraceTime(Debug, gc) debug("Clear Next Bitmap");
1968 clear_bitmap(_next_mark_bitmap, _g1h->workers(), false);
1969 }
1970 // Note we cannot clear the previous marking bitmap here
1971 // since VerifyDuringGC verifies the objects marked during
1972 // a full GC against the previous bitmap.
1973
1974 // Empty mark stack
1975 reset_marking_for_restart();
1976 for (uint i = 0; i < _max_num_tasks; ++i) {
1977 _tasks[i]->clear_region_fields();
1978 }
1979 _first_overflow_barrier_sync.abort();
1980 _second_overflow_barrier_sync.abort();
1981 _has_aborted = true;
1982
1983 SATBMarkQueueSet& satb_mq_set = G1BarrierSet::satb_mark_queue_set();
1984 satb_mq_set.abandon_partial_marking();
1985 // This can be called either during or outside marking, we'll read
1986 // the expected_active value from the SATB queue set.
1987 satb_mq_set.set_active_all_threads(
1988 false, /* new active value */
1989 satb_mq_set.is_active() /* expected_active */);
1990 }
1991
1992 static void print_ms_time_info(const char* prefix, const char* name,
1993 NumberSeq& ns) {
1994 log_trace(gc, marking)("%s%5d %12s: total time = %8.2f s (avg = %8.2f ms).",
1995 prefix, ns.num(), name, ns.sum()/1000.0, ns.avg());
1996 if (ns.num() > 0) {
1997 log_trace(gc, marking)("%s [std. dev = %8.2f ms, max = %8.2f ms]",
1998 prefix, ns.sd(), ns.maximum());
1999 }
2000 }
2001
2002 void G1ConcurrentMark::print_summary_info() {
2003 Log(gc, marking) log;
2004 if (!log.is_trace()) {
2005 return;
2006 }
2007
2008 log.trace(" Concurrent marking:");
2009 print_ms_time_info(" ", "init marks", _init_times);
2010 print_ms_time_info(" ", "remarks", _remark_times);
2011 {
2012 print_ms_time_info(" ", "final marks", _remark_mark_times);
2013 print_ms_time_info(" ", "weak refs", _remark_weak_ref_times);
2014
2015 }
2016 print_ms_time_info(" ", "cleanups", _cleanup_times);
2017 log.trace(" Finalize live data total time = %8.2f s (avg = %8.2f ms).",
2018 _total_cleanup_time, (_cleanup_times.num() > 0 ? _total_cleanup_time * 1000.0 / (double)_cleanup_times.num() : 0.0));
2019 log.trace(" Total stop_world time = %8.2f s.",
2020 (_init_times.sum() + _remark_times.sum() + _cleanup_times.sum())/1000.0);
2021 log.trace(" Total concurrent time = %8.2f s (%8.2f s marking).",
2022 cm_thread()->vtime_accum(), cm_thread()->vtime_mark_accum());
2023 }
2024
2025 void G1ConcurrentMark::threads_do(ThreadClosure* tc) const {
2026 _concurrent_workers->threads_do(tc);
2027 }
2028
2029 void G1ConcurrentMark::print_on_error(outputStream* st) const {
2030 st->print_cr("Marking Bits (Prev, Next): (CMBitMap*) " PTR_FORMAT ", (CMBitMap*) " PTR_FORMAT,
2031 p2i(_prev_mark_bitmap), p2i(_next_mark_bitmap));
2032 _prev_mark_bitmap->print_on_error(st, " Prev Bits: ");
2033 _next_mark_bitmap->print_on_error(st, " Next Bits: ");
2034 }
2035
2036 static ReferenceProcessor* get_cm_oop_closure_ref_processor(G1CollectedHeap* g1h) {
2037 ReferenceProcessor* result = g1h->ref_processor_cm();
2038 assert(result != NULL, "CM reference processor should not be NULL");
2039 return result;
2040 }
2041
2042 G1CMOopClosure::G1CMOopClosure(G1CollectedHeap* g1h,
2043 G1CMTask* task)
2044 : MetadataVisitingOopIterateClosure(get_cm_oop_closure_ref_processor(g1h)),
2045 _g1h(g1h), _task(task)
2046 { }
2047
2048 void G1CMTask::setup_for_region(HeapRegion* hr) {
2049 assert(hr != NULL,
2050 "claim_region() should have filtered out NULL regions");
2051 _curr_region = hr;
2052 _finger = hr->bottom();
2053 update_region_limit();
2054 }
2055
2056 void G1CMTask::update_region_limit() {
2057 HeapRegion* hr = _curr_region;
2058 HeapWord* bottom = hr->bottom();
2059 HeapWord* limit = hr->next_top_at_mark_start();
2060
2061 if (limit == bottom) {
2062 // The region was collected underneath our feet.
2063 // We set the finger to bottom to ensure that the bitmap
2064 // iteration that will follow this will not do anything.
2065 // (this is not a condition that holds when we set the region up,
2066 // as the region is not supposed to be empty in the first place)
2067 _finger = bottom;
2068 } else if (limit >= _region_limit) {
2069 assert(limit >= _finger, "peace of mind");
2070 } else {
2071 assert(limit < _region_limit, "only way to get here");
2072 // This can happen under some pretty unusual circumstances. An
2073 // evacuation pause empties the region underneath our feet (NTAMS
2074 // at bottom). We then do some allocation in the region (NTAMS
2075 // stays at bottom), followed by the region being used as a GC
2076 // alloc region (NTAMS will move to top() and the objects
2077 // originally below it will be grayed). All objects now marked in
2078 // the region are explicitly grayed, if below the global finger,
2079 // and we do not need in fact to scan anything else. So, we simply
2080 // set _finger to be limit to ensure that the bitmap iteration
2081 // doesn't do anything.
2082 _finger = limit;
2083 }
2084
2085 _region_limit = limit;
2086 }
2087
2088 void G1CMTask::giveup_current_region() {
2089 assert(_curr_region != NULL, "invariant");
2090 clear_region_fields();
2091 }
2092
2093 void G1CMTask::clear_region_fields() {
2094 // Values for these three fields that indicate that we're not
2095 // holding on to a region.
2096 _curr_region = NULL;
2097 _finger = NULL;
2098 _region_limit = NULL;
2099 }
2100
2101 void G1CMTask::set_cm_oop_closure(G1CMOopClosure* cm_oop_closure) {
2102 if (cm_oop_closure == NULL) {
2103 assert(_cm_oop_closure != NULL, "invariant");
2104 } else {
2105 assert(_cm_oop_closure == NULL, "invariant");
2106 }
2107 _cm_oop_closure = cm_oop_closure;
2108 }
2109
2110 void G1CMTask::reset(G1CMBitMap* next_mark_bitmap) {
2111 guarantee(next_mark_bitmap != NULL, "invariant");
2112 _next_mark_bitmap = next_mark_bitmap;
2113 clear_region_fields();
2114
2115 _calls = 0;
2116 _elapsed_time_ms = 0.0;
2117 _termination_time_ms = 0.0;
2118 _termination_start_time_ms = 0.0;
2119
2120 _mark_stats_cache.reset();
2121 }
2122
2123 bool G1CMTask::should_exit_termination() {
2124 if (!regular_clock_call()) {
2125 return true;
2126 }
2127
2128 // This is called when we are in the termination protocol. We should
2129 // quit if, for some reason, this task wants to abort or the global
2130 // stack is not empty (this means that we can get work from it).
2131 return !_cm->mark_stack_empty() || has_aborted();
2132 }
2133
2134 void G1CMTask::reached_limit() {
2135 assert(_words_scanned >= _words_scanned_limit ||
2136 _refs_reached >= _refs_reached_limit ,
2137 "shouldn't have been called otherwise");
2138 abort_marking_if_regular_check_fail();
2139 }
2140
2141 bool G1CMTask::regular_clock_call() {
2142 if (has_aborted()) {
2143 return false;
2144 }
2145
2146 // First, we need to recalculate the words scanned and refs reached
2147 // limits for the next clock call.
2148 recalculate_limits();
2149
2150 // During the regular clock call we do the following
2151
2152 // (1) If an overflow has been flagged, then we abort.
2153 if (_cm->has_overflown()) {
2154 return false;
2155 }
2156
2157 // If we are not concurrent (i.e. we're doing remark) we don't need
2158 // to check anything else. The other steps are only needed during
2159 // the concurrent marking phase.
2160 if (!_cm->concurrent()) {
2161 return true;
2162 }
2163
2164 // (2) If marking has been aborted for Full GC, then we also abort.
2165 if (_cm->has_aborted()) {
2166 return false;
2167 }
2168
2169 double curr_time_ms = os::elapsedVTime() * 1000.0;
2170
2171 // (4) We check whether we should yield. If we have to, then we abort.
2172 if (SuspendibleThreadSet::should_yield()) {
2173 // We should yield. To do this we abort the task. The caller is
2174 // responsible for yielding.
2175 return false;
2176 }
2177
2178 // (5) We check whether we've reached our time quota. If we have,
2179 // then we abort.
2180 double elapsed_time_ms = curr_time_ms - _start_time_ms;
2181 if (elapsed_time_ms > _time_target_ms) {
2182 _has_timed_out = true;
2183 return false;
2184 }
2185
2186 // (6) Finally, we check whether there are enough completed STAB
2187 // buffers available for processing. If there are, we abort.
2188 SATBMarkQueueSet& satb_mq_set = G1BarrierSet::satb_mark_queue_set();
2189 if (!_draining_satb_buffers && satb_mq_set.process_completed_buffers()) {
2190 // we do need to process SATB buffers, we'll abort and restart
2191 // the marking task to do so
2192 return false;
2193 }
2194 return true;
2195 }
2196
2197 void G1CMTask::recalculate_limits() {
2198 _real_words_scanned_limit = _words_scanned + words_scanned_period;
2199 _words_scanned_limit = _real_words_scanned_limit;
2200
2201 _real_refs_reached_limit = _refs_reached + refs_reached_period;
2202 _refs_reached_limit = _real_refs_reached_limit;
2203 }
2204
2205 void G1CMTask::decrease_limits() {
2206 // This is called when we believe that we're going to do an infrequent
2207 // operation which will increase the per byte scanned cost (i.e. move
2208 // entries to/from the global stack). It basically tries to decrease the
2209 // scanning limit so that the clock is called earlier.
2210
2211 _words_scanned_limit = _real_words_scanned_limit - 3 * words_scanned_period / 4;
2212 _refs_reached_limit = _real_refs_reached_limit - 3 * refs_reached_period / 4;
2213 }
2214
2215 void G1CMTask::move_entries_to_global_stack() {
2216 // Local array where we'll store the entries that will be popped
2217 // from the local queue.
2218 G1TaskQueueEntry buffer[G1CMMarkStack::EntriesPerChunk];
2219
2220 size_t n = 0;
2221 G1TaskQueueEntry task_entry;
2222 while (n < G1CMMarkStack::EntriesPerChunk && _task_queue->pop_local(task_entry)) {
2223 buffer[n] = task_entry;
2224 ++n;
2225 }
2226 if (n < G1CMMarkStack::EntriesPerChunk) {
2227 buffer[n] = G1TaskQueueEntry();
2228 }
2229
2230 if (n > 0) {
2231 if (!_cm->mark_stack_push(buffer)) {
2232 set_has_aborted();
2233 }
2234 }
2235
2236 // This operation was quite expensive, so decrease the limits.
2237 decrease_limits();
2238 }
2239
2240 bool G1CMTask::get_entries_from_global_stack() {
2241 // Local array where we'll store the entries that will be popped
2242 // from the global stack.
2243 G1TaskQueueEntry buffer[G1CMMarkStack::EntriesPerChunk];
2244
2245 if (!_cm->mark_stack_pop(buffer)) {
2246 return false;
2247 }
2248
2249 // We did actually pop at least one entry.
2250 for (size_t i = 0; i < G1CMMarkStack::EntriesPerChunk; ++i) {
2251 G1TaskQueueEntry task_entry = buffer[i];
2252 if (task_entry.is_null()) {
2253 break;
2254 }
2255 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()));
2256 bool success = _task_queue->push(task_entry);
2257 // We only call this when the local queue is empty or under a
2258 // given target limit. So, we do not expect this push to fail.
2259 assert(success, "invariant");
2260 }
2261
2262 // This operation was quite expensive, so decrease the limits
2263 decrease_limits();
2264 return true;
2265 }
2266
2267 void G1CMTask::drain_local_queue(bool partially) {
2268 if (has_aborted()) {
2269 return;
2270 }
2271
2272 // Decide what the target size is, depending whether we're going to
2273 // drain it partially (so that other tasks can steal if they run out
2274 // of things to do) or totally (at the very end).
2275 size_t target_size;
2276 if (partially) {
2277 target_size = MIN2((size_t)_task_queue->max_elems()/3, (size_t)GCDrainStackTargetSize);
2278 } else {
2279 target_size = 0;
2280 }
2281
2282 if (_task_queue->size() > target_size) {
2283 G1TaskQueueEntry entry;
2284 bool ret = _task_queue->pop_local(entry);
2285 while (ret) {
2286 scan_task_entry(entry);
2287 if (_task_queue->size() <= target_size || has_aborted()) {
2288 ret = false;
2289 } else {
2290 ret = _task_queue->pop_local(entry);
2291 }
2292 }
2293 }
2294 }
2295
2296 void G1CMTask::drain_global_stack(bool partially) {
2297 if (has_aborted()) {
2298 return;
2299 }
2300
2301 // We have a policy to drain the local queue before we attempt to
2302 // drain the global stack.
2303 assert(partially || _task_queue->size() == 0, "invariant");
2304
2305 // Decide what the target size is, depending whether we're going to
2306 // drain it partially (so that other tasks can steal if they run out
2307 // of things to do) or totally (at the very end).
2308 // Notice that when draining the global mark stack partially, due to the racyness
2309 // of the mark stack size update we might in fact drop below the target. But,
2310 // this is not a problem.
2311 // In case of total draining, we simply process until the global mark stack is
2312 // totally empty, disregarding the size counter.
2313 if (partially) {
2314 size_t const target_size = _cm->partial_mark_stack_size_target();
2315 while (!has_aborted() && _cm->mark_stack_size() > target_size) {
2316 if (get_entries_from_global_stack()) {
2317 drain_local_queue(partially);
2318 }
2319 }
2320 } else {
2321 while (!has_aborted() && get_entries_from_global_stack()) {
2322 drain_local_queue(partially);
2323 }
2324 }
2325 }
2326
2327 // SATB Queue has several assumptions on whether to call the par or
2328 // non-par versions of the methods. this is why some of the code is
2329 // replicated. We should really get rid of the single-threaded version
2330 // of the code to simplify things.
2331 void G1CMTask::drain_satb_buffers() {
2332 if (has_aborted()) {
2333 return;
2334 }
2335
2336 // We set this so that the regular clock knows that we're in the
2337 // middle of draining buffers and doesn't set the abort flag when it
2338 // notices that SATB buffers are available for draining. It'd be
2339 // very counter productive if it did that. :-)
2340 _draining_satb_buffers = true;
2341
2342 G1CMSATBBufferClosure satb_cl(this, _g1h);
2343 SATBMarkQueueSet& satb_mq_set = G1BarrierSet::satb_mark_queue_set();
2344
2345 // This keeps claiming and applying the closure to completed buffers
2346 // until we run out of buffers or we need to abort.
2347 while (!has_aborted() &&
2348 satb_mq_set.apply_closure_to_completed_buffer(&satb_cl)) {
2349 abort_marking_if_regular_check_fail();
2350 }
2351
2352 // Can't assert qset is empty here, even if not aborted. If concurrent,
2353 // some other thread might be adding to the queue. If not concurrent,
2354 // some other thread might have won the race for the last buffer, but
2355 // has not yet decremented the count.
2356
2357 _draining_satb_buffers = false;
2358
2359 // again, this was a potentially expensive operation, decrease the
2360 // limits to get the regular clock call early
2361 decrease_limits();
2362 }
2363
2364 void G1CMTask::clear_mark_stats_cache(uint region_idx) {
2365 _mark_stats_cache.reset(region_idx);
2366 }
2367
2368 Pair<size_t, size_t> G1CMTask::flush_mark_stats_cache() {
2369 return _mark_stats_cache.evict_all();
2370 }
2371
2372 void G1CMTask::print_stats() {
2373 log_debug(gc, stats)("Marking Stats, task = %u, calls = %u", _worker_id, _calls);
2374 log_debug(gc, stats)(" Elapsed time = %1.2lfms, Termination time = %1.2lfms",
2375 _elapsed_time_ms, _termination_time_ms);
2376 log_debug(gc, stats)(" Step Times (cum): num = %d, avg = %1.2lfms, sd = %1.2lfms max = %1.2lfms, total = %1.2lfms",
2377 _step_times_ms.num(),
2378 _step_times_ms.avg(),
2379 _step_times_ms.sd(),
2380 _step_times_ms.maximum(),
2381 _step_times_ms.sum());
2382 size_t const hits = _mark_stats_cache.hits();
2383 size_t const misses = _mark_stats_cache.misses();
2384 log_debug(gc, stats)(" Mark Stats Cache: hits " SIZE_FORMAT " misses " SIZE_FORMAT " ratio %.3f",
2385 hits, misses, percent_of(hits, hits + misses));
2386 }
2387
2388 bool G1ConcurrentMark::try_stealing(uint worker_id, G1TaskQueueEntry& task_entry) {
2389 return _task_queues->steal(worker_id, task_entry);
2390 }
2391
2392 /*****************************************************************************
2393
2394 The do_marking_step(time_target_ms, ...) method is the building
2395 block of the parallel marking framework. It can be called in parallel
2396 with other invocations of do_marking_step() on different tasks
2397 (but only one per task, obviously) and concurrently with the
2398 mutator threads, or during remark, hence it eliminates the need
2399 for two versions of the code. When called during remark, it will
2400 pick up from where the task left off during the concurrent marking
2401 phase. Interestingly, tasks are also claimable during evacuation
2402 pauses too, since do_marking_step() ensures that it aborts before
2403 it needs to yield.
2404
2405 The data structures that it uses to do marking work are the
2406 following:
2407
2408 (1) Marking Bitmap. If there are gray objects that appear only
2409 on the bitmap (this happens either when dealing with an overflow
2410 or when the concurrent start pause has simply marked the roots
2411 and didn't push them on the stack), then tasks claim heap
2412 regions whose bitmap they then scan to find gray objects. A
2413 global finger indicates where the end of the last claimed region
2414 is. A local finger indicates how far into the region a task has
2415 scanned. The two fingers are used to determine how to gray an
2416 object (i.e. whether simply marking it is OK, as it will be
2417 visited by a task in the future, or whether it needs to be also
2418 pushed on a stack).
2419
2420 (2) Local Queue. The local queue of the task which is accessed
2421 reasonably efficiently by the task. Other tasks can steal from
2422 it when they run out of work. Throughout the marking phase, a
2423 task attempts to keep its local queue short but not totally
2424 empty, so that entries are available for stealing by other
2425 tasks. Only when there is no more work, a task will totally
2426 drain its local queue.
2427
2428 (3) Global Mark Stack. This handles local queue overflow. During
2429 marking only sets of entries are moved between it and the local
2430 queues, as access to it requires a mutex and more fine-grain
2431 interaction with it which might cause contention. If it
2432 overflows, then the marking phase should restart and iterate
2433 over the bitmap to identify gray objects. Throughout the marking
2434 phase, tasks attempt to keep the global mark stack at a small
2435 length but not totally empty, so that entries are available for
2436 popping by other tasks. Only when there is no more work, tasks
2437 will totally drain the global mark stack.
2438
2439 (4) SATB Buffer Queue. This is where completed SATB buffers are
2440 made available. Buffers are regularly removed from this queue
2441 and scanned for roots, so that the queue doesn't get too
2442 long. During remark, all completed buffers are processed, as
2443 well as the filled in parts of any uncompleted buffers.
2444
2445 The do_marking_step() method tries to abort when the time target
2446 has been reached. There are a few other cases when the
2447 do_marking_step() method also aborts:
2448
2449 (1) When the marking phase has been aborted (after a Full GC).
2450
2451 (2) When a global overflow (on the global stack) has been
2452 triggered. Before the task aborts, it will actually sync up with
2453 the other tasks to ensure that all the marking data structures
2454 (local queues, stacks, fingers etc.) are re-initialized so that
2455 when do_marking_step() completes, the marking phase can
2456 immediately restart.
2457
2458 (3) When enough completed SATB buffers are available. The
2459 do_marking_step() method only tries to drain SATB buffers right
2460 at the beginning. So, if enough buffers are available, the
2461 marking step aborts and the SATB buffers are processed at
2462 the beginning of the next invocation.
2463
2464 (4) To yield. when we have to yield then we abort and yield
2465 right at the end of do_marking_step(). This saves us from a lot
2466 of hassle as, by yielding we might allow a Full GC. If this
2467 happens then objects will be compacted underneath our feet, the
2468 heap might shrink, etc. We save checking for this by just
2469 aborting and doing the yield right at the end.
2470
2471 From the above it follows that the do_marking_step() method should
2472 be called in a loop (or, otherwise, regularly) until it completes.
2473
2474 If a marking step completes without its has_aborted() flag being
2475 true, it means it has completed the current marking phase (and
2476 also all other marking tasks have done so and have all synced up).
2477
2478 A method called regular_clock_call() is invoked "regularly" (in
2479 sub ms intervals) throughout marking. It is this clock method that
2480 checks all the abort conditions which were mentioned above and
2481 decides when the task should abort. A work-based scheme is used to
2482 trigger this clock method: when the number of object words the
2483 marking phase has scanned or the number of references the marking
2484 phase has visited reach a given limit. Additional invocations to
2485 the method clock have been planted in a few other strategic places
2486 too. The initial reason for the clock method was to avoid calling
2487 vtime too regularly, as it is quite expensive. So, once it was in
2488 place, it was natural to piggy-back all the other conditions on it
2489 too and not constantly check them throughout the code.
2490
2491 If do_termination is true then do_marking_step will enter its
2492 termination protocol.
2493
2494 The value of is_serial must be true when do_marking_step is being
2495 called serially (i.e. by the VMThread) and do_marking_step should
2496 skip any synchronization in the termination and overflow code.
2497 Examples include the serial remark code and the serial reference
2498 processing closures.
2499
2500 The value of is_serial must be false when do_marking_step is
2501 being called by any of the worker threads in a work gang.
2502 Examples include the concurrent marking code (CMMarkingTask),
2503 the MT remark code, and the MT reference processing closures.
2504
2505 *****************************************************************************/
2506
2507 void G1CMTask::do_marking_step(double time_target_ms,
2508 bool do_termination,
2509 bool is_serial) {
2510 assert(time_target_ms >= 1.0, "minimum granularity is 1ms");
2511
2512 _start_time_ms = os::elapsedVTime() * 1000.0;
2513
2514 // If do_stealing is true then do_marking_step will attempt to
2515 // steal work from the other G1CMTasks. It only makes sense to
2516 // enable stealing when the termination protocol is enabled
2517 // and do_marking_step() is not being called serially.
2518 bool do_stealing = do_termination && !is_serial;
2519
2520 G1Predictions const& predictor = _g1h->policy()->predictor();
2521 double diff_prediction_ms = predictor.predict_zero_bounded(&_marking_step_diff_ms);
2522 _time_target_ms = time_target_ms - diff_prediction_ms;
2523
2524 // set up the variables that are used in the work-based scheme to
2525 // call the regular clock method
2526 _words_scanned = 0;
2527 _refs_reached = 0;
2528 recalculate_limits();
2529
2530 // clear all flags
2531 clear_has_aborted();
2532 _has_timed_out = false;
2533 _draining_satb_buffers = false;
2534
2535 ++_calls;
2536
2537 // Set up the bitmap and oop closures. Anything that uses them is
2538 // eventually called from this method, so it is OK to allocate these
2539 // statically.
2540 G1CMBitMapClosure bitmap_closure(this, _cm);
2541 G1CMOopClosure cm_oop_closure(_g1h, this);
2542 set_cm_oop_closure(&cm_oop_closure);
2543
2544 if (_cm->has_overflown()) {
2545 // This can happen if the mark stack overflows during a GC pause
2546 // and this task, after a yield point, restarts. We have to abort
2547 // as we need to get into the overflow protocol which happens
2548 // right at the end of this task.
2549 set_has_aborted();
2550 }
2551
2552 // First drain any available SATB buffers. After this, we will not
2553 // look at SATB buffers before the next invocation of this method.
2554 // If enough completed SATB buffers are queued up, the regular clock
2555 // will abort this task so that it restarts.
2556 drain_satb_buffers();
2557 // ...then partially drain the local queue and the global stack
2558 drain_local_queue(true);
2559 drain_global_stack(true);
2560
2561 do {
2562 if (!has_aborted() && _curr_region != NULL) {
2563 // This means that we're already holding on to a region.
2564 assert(_finger != NULL, "if region is not NULL, then the finger "
2565 "should not be NULL either");
2566
2567 // We might have restarted this task after an evacuation pause
2568 // which might have evacuated the region we're holding on to
2569 // underneath our feet. Let's read its limit again to make sure
2570 // that we do not iterate over a region of the heap that
2571 // contains garbage (update_region_limit() will also move
2572 // _finger to the start of the region if it is found empty).
2573 update_region_limit();
2574 // We will start from _finger not from the start of the region,
2575 // as we might be restarting this task after aborting half-way
2576 // through scanning this region. In this case, _finger points to
2577 // the address where we last found a marked object. If this is a
2578 // fresh region, _finger points to start().
2579 MemRegion mr = MemRegion(_finger, _region_limit);
2580
2581 assert(!_curr_region->is_humongous() || mr.start() == _curr_region->bottom(),
2582 "humongous regions should go around loop once only");
2583
2584 // Some special cases:
2585 // If the memory region is empty, we can just give up the region.
2586 // If the current region is humongous then we only need to check
2587 // the bitmap for the bit associated with the start of the object,
2588 // scan the object if it's live, and give up the region.
2589 // Otherwise, let's iterate over the bitmap of the part of the region
2590 // that is left.
2591 // If the iteration is successful, give up the region.
2592 if (mr.is_empty()) {
2593 giveup_current_region();
2594 abort_marking_if_regular_check_fail();
2595 } else if (_curr_region->is_humongous() && mr.start() == _curr_region->bottom()) {
2596 if (_next_mark_bitmap->is_marked(mr.start())) {
2597 // The object is marked - apply the closure
2598 bitmap_closure.do_addr(mr.start());
2599 }
2600 // Even if this task aborted while scanning the humongous object
2601 // we can (and should) give up the current region.
2602 giveup_current_region();
2603 abort_marking_if_regular_check_fail();
2604 } else if (_next_mark_bitmap->iterate(&bitmap_closure, mr)) {
2605 giveup_current_region();
2606 abort_marking_if_regular_check_fail();
2607 } else {
2608 assert(has_aborted(), "currently the only way to do so");
2609 // The only way to abort the bitmap iteration is to return
2610 // false from the do_bit() method. However, inside the
2611 // do_bit() method we move the _finger to point to the
2612 // object currently being looked at. So, if we bail out, we
2613 // have definitely set _finger to something non-null.
2614 assert(_finger != NULL, "invariant");
2615
2616 // Region iteration was actually aborted. So now _finger
2617 // points to the address of the object we last scanned. If we
2618 // leave it there, when we restart this task, we will rescan
2619 // the object. It is easy to avoid this. We move the finger by
2620 // enough to point to the next possible object header.
2621 assert(_finger < _region_limit, "invariant");
2622 HeapWord* const new_finger = _finger + ((oop)_finger)->size();
2623 // Check if bitmap iteration was aborted while scanning the last object
2624 if (new_finger >= _region_limit) {
2625 giveup_current_region();
2626 } else {
2627 move_finger_to(new_finger);
2628 }
2629 }
2630 }
2631 // At this point we have either completed iterating over the
2632 // region we were holding on to, or we have aborted.
2633
2634 // We then partially drain the local queue and the global stack.
2635 // (Do we really need this?)
2636 drain_local_queue(true);
2637 drain_global_stack(true);
2638
2639 // Read the note on the claim_region() method on why it might
2640 // return NULL with potentially more regions available for
2641 // claiming and why we have to check out_of_regions() to determine
2642 // whether we're done or not.
2643 while (!has_aborted() && _curr_region == NULL && !_cm->out_of_regions()) {
2644 // We are going to try to claim a new region. We should have
2645 // given up on the previous one.
2646 // Separated the asserts so that we know which one fires.
2647 assert(_curr_region == NULL, "invariant");
2648 assert(_finger == NULL, "invariant");
2649 assert(_region_limit == NULL, "invariant");
2650 HeapRegion* claimed_region = _cm->claim_region(_worker_id);
2651 if (claimed_region != NULL) {
2652 // Yes, we managed to claim one
2653 setup_for_region(claimed_region);
2654 assert(_curr_region == claimed_region, "invariant");
2655 }
2656 // It is important to call the regular clock here. It might take
2657 // a while to claim a region if, for example, we hit a large
2658 // block of empty regions. So we need to call the regular clock
2659 // method once round the loop to make sure it's called
2660 // frequently enough.
2661 abort_marking_if_regular_check_fail();
2662 }
2663
2664 if (!has_aborted() && _curr_region == NULL) {
2665 assert(_cm->out_of_regions(),
2666 "at this point we should be out of regions");
2667 }
2668 } while ( _curr_region != NULL && !has_aborted());
2669
2670 if (!has_aborted()) {
2671 // We cannot check whether the global stack is empty, since other
2672 // tasks might be pushing objects to it concurrently.
2673 assert(_cm->out_of_regions(),
2674 "at this point we should be out of regions");
2675 // Try to reduce the number of available SATB buffers so that
2676 // remark has less work to do.
2677 drain_satb_buffers();
2678 }
2679
2680 // Since we've done everything else, we can now totally drain the
2681 // local queue and global stack.
2682 drain_local_queue(false);
2683 drain_global_stack(false);
2684
2685 // Attempt at work stealing from other task's queues.
2686 if (do_stealing && !has_aborted()) {
2687 // We have not aborted. This means that we have finished all that
2688 // we could. Let's try to do some stealing...
2689
2690 // We cannot check whether the global stack is empty, since other
2691 // tasks might be pushing objects to it concurrently.
2692 assert(_cm->out_of_regions() && _task_queue->size() == 0,
2693 "only way to reach here");
2694 while (!has_aborted()) {
2695 G1TaskQueueEntry entry;
2696 if (_cm->try_stealing(_worker_id, entry)) {
2697 scan_task_entry(entry);
2698
2699 // And since we're towards the end, let's totally drain the
2700 // local queue and global stack.
2701 drain_local_queue(false);
2702 drain_global_stack(false);
2703 } else {
2704 break;
2705 }
2706 }
2707 }
2708
2709 // We still haven't aborted. Now, let's try to get into the
2710 // termination protocol.
2711 if (do_termination && !has_aborted()) {
2712 // We cannot check whether the global stack is empty, since other
2713 // tasks might be concurrently pushing objects on it.
2714 // Separated the asserts so that we know which one fires.
2715 assert(_cm->out_of_regions(), "only way to reach here");
2716 assert(_task_queue->size() == 0, "only way to reach here");
2717 _termination_start_time_ms = os::elapsedVTime() * 1000.0;
2718
2719 // The G1CMTask class also extends the TerminatorTerminator class,
2720 // hence its should_exit_termination() method will also decide
2721 // whether to exit the termination protocol or not.
2722 bool finished = (is_serial ||
2723 _cm->terminator()->offer_termination(this));
2724 double termination_end_time_ms = os::elapsedVTime() * 1000.0;
2725 _termination_time_ms +=
2726 termination_end_time_ms - _termination_start_time_ms;
2727
2728 if (finished) {
2729 // We're all done.
2730
2731 // We can now guarantee that the global stack is empty, since
2732 // all other tasks have finished. We separated the guarantees so
2733 // that, if a condition is false, we can immediately find out
2734 // which one.
2735 guarantee(_cm->out_of_regions(), "only way to reach here");
2736 guarantee(_cm->mark_stack_empty(), "only way to reach here");
2737 guarantee(_task_queue->size() == 0, "only way to reach here");
2738 guarantee(!_cm->has_overflown(), "only way to reach here");
2739 guarantee(!has_aborted(), "should never happen if termination has completed");
2740 } else {
2741 // Apparently there's more work to do. Let's abort this task. It
2742 // will restart it and we can hopefully find more things to do.
2743 set_has_aborted();
2744 }
2745 }
2746
2747 // Mainly for debugging purposes to make sure that a pointer to the
2748 // closure which was statically allocated in this frame doesn't
2749 // escape it by accident.
2750 set_cm_oop_closure(NULL);
2751 double end_time_ms = os::elapsedVTime() * 1000.0;
2752 double elapsed_time_ms = end_time_ms - _start_time_ms;
2753 // Update the step history.
2754 _step_times_ms.add(elapsed_time_ms);
2755
2756 if (has_aborted()) {
2757 // The task was aborted for some reason.
2758 if (_has_timed_out) {
2759 double diff_ms = elapsed_time_ms - _time_target_ms;
2760 // Keep statistics of how well we did with respect to hitting
2761 // our target only if we actually timed out (if we aborted for
2762 // other reasons, then the results might get skewed).
2763 _marking_step_diff_ms.add(diff_ms);
2764 }
2765
2766 if (_cm->has_overflown()) {
2767 // This is the interesting one. We aborted because a global
2768 // overflow was raised. This means we have to restart the
2769 // marking phase and start iterating over regions. However, in
2770 // order to do this we have to make sure that all tasks stop
2771 // what they are doing and re-initialize in a safe manner. We
2772 // will achieve this with the use of two barrier sync points.
2773
2774 if (!is_serial) {
2775 // We only need to enter the sync barrier if being called
2776 // from a parallel context
2777 _cm->enter_first_sync_barrier(_worker_id);
2778
2779 // When we exit this sync barrier we know that all tasks have
2780 // stopped doing marking work. So, it's now safe to
2781 // re-initialize our data structures.
2782 }
2783
2784 clear_region_fields();
2785 flush_mark_stats_cache();
2786
2787 if (!is_serial) {
2788 // If we're executing the concurrent phase of marking, reset the marking
2789 // state; otherwise the marking state is reset after reference processing,
2790 // during the remark pause.
2791 // If we reset here as a result of an overflow during the remark we will
2792 // see assertion failures from any subsequent set_concurrency_and_phase()
2793 // calls.
2794 if (_cm->concurrent() && _worker_id == 0) {
2795 // Worker 0 is responsible for clearing the global data structures because
2796 // of an overflow. During STW we should not clear the overflow flag (in
2797 // G1ConcurrentMark::reset_marking_state()) since we rely on it being true when we exit
2798 // method to abort the pause and restart concurrent marking.
2799 _cm->reset_marking_for_restart();
2800
2801 log_info(gc, marking)("Concurrent Mark reset for overflow");
2802 }
2803
2804 // ...and enter the second barrier.
2805 _cm->enter_second_sync_barrier(_worker_id);
2806 }
2807 // At this point, if we're during the concurrent phase of
2808 // marking, everything has been re-initialized and we're
2809 // ready to restart.
2810 }
2811 }
2812 }
2813
2814 G1CMTask::G1CMTask(uint worker_id,
2815 G1ConcurrentMark* cm,
2816 G1CMTaskQueue* task_queue,
2817 G1RegionMarkStats* mark_stats) :
2818 _objArray_processor(this),
2819 _worker_id(worker_id),
2820 _g1h(G1CollectedHeap::heap()),
2821 _cm(cm),
2822 _next_mark_bitmap(NULL),
2823 _task_queue(task_queue),
2824 _mark_stats_cache(mark_stats, RegionMarkStatsCacheSize),
2825 _calls(0),
2826 _time_target_ms(0.0),
2827 _start_time_ms(0.0),
2828 _cm_oop_closure(NULL),
2829 _curr_region(NULL),
2830 _finger(NULL),
2831 _region_limit(NULL),
2832 _words_scanned(0),
2833 _words_scanned_limit(0),
2834 _real_words_scanned_limit(0),
2835 _refs_reached(0),
2836 _refs_reached_limit(0),
2837 _real_refs_reached_limit(0),
2838 _has_aborted(false),
2839 _has_timed_out(false),
2840 _draining_satb_buffers(false),
2841 _step_times_ms(),
2842 _elapsed_time_ms(0.0),
2843 _termination_time_ms(0.0),
2844 _termination_start_time_ms(0.0),
2845 _marking_step_diff_ms()
2846 {
2847 guarantee(task_queue != NULL, "invariant");
2848
2849 _marking_step_diff_ms.add(0.5);
2850 }
2851
2852 // These are formatting macros that are used below to ensure
2853 // consistent formatting. The *_H_* versions are used to format the
2854 // header for a particular value and they should be kept consistent
2855 // with the corresponding macro. Also note that most of the macros add
2856 // the necessary white space (as a prefix) which makes them a bit
2857 // easier to compose.
2858
2859 // All the output lines are prefixed with this string to be able to
2860 // identify them easily in a large log file.
2861 #define G1PPRL_LINE_PREFIX "###"
2862
2863 #define G1PPRL_ADDR_BASE_FORMAT " " PTR_FORMAT "-" PTR_FORMAT
2864 #ifdef _LP64
2865 #define G1PPRL_ADDR_BASE_H_FORMAT " %37s"
2866 #else // _LP64
2867 #define G1PPRL_ADDR_BASE_H_FORMAT " %21s"
2868 #endif // _LP64
2869
2870 // For per-region info
2871 #define G1PPRL_TYPE_FORMAT " %-4s"
2872 #define G1PPRL_TYPE_H_FORMAT " %4s"
2873 #define G1PPRL_STATE_FORMAT " %-5s"
2874 #define G1PPRL_STATE_H_FORMAT " %5s"
2875 #define G1PPRL_BYTE_FORMAT " " SIZE_FORMAT_W(9)
2876 #define G1PPRL_BYTE_H_FORMAT " %9s"
2877 #define G1PPRL_DOUBLE_FORMAT " %14.1f"
2878 #define G1PPRL_DOUBLE_H_FORMAT " %14s"
2879
2880 // For summary info
2881 #define G1PPRL_SUM_ADDR_FORMAT(tag) " " tag ":" G1PPRL_ADDR_BASE_FORMAT
2882 #define G1PPRL_SUM_BYTE_FORMAT(tag) " " tag ": " SIZE_FORMAT
2883 #define G1PPRL_SUM_MB_FORMAT(tag) " " tag ": %1.2f MB"
2884 #define G1PPRL_SUM_MB_PERC_FORMAT(tag) G1PPRL_SUM_MB_FORMAT(tag) " / %1.2f %%"
2885
2886 G1PrintRegionLivenessInfoClosure::G1PrintRegionLivenessInfoClosure(const char* phase_name) :
2887 _total_used_bytes(0), _total_capacity_bytes(0),
2888 _total_prev_live_bytes(0), _total_next_live_bytes(0),
2889 _total_remset_bytes(0), _total_strong_code_roots_bytes(0)
2890 {
2891 if (!log_is_enabled(Trace, gc, liveness)) {
2892 return;
2893 }
2894
2895 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2896 MemRegion g1_reserved = g1h->g1_reserved();
2897 double now = os::elapsedTime();
2898
2899 // Print the header of the output.
2900 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX" PHASE %s @ %1.3f", phase_name, now);
2901 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX" HEAP"
2902 G1PPRL_SUM_ADDR_FORMAT("reserved")
2903 G1PPRL_SUM_BYTE_FORMAT("region-size"),
2904 p2i(g1_reserved.start()), p2i(g1_reserved.end()),
2905 HeapRegion::GrainBytes);
2906 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX);
2907 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX
2908 G1PPRL_TYPE_H_FORMAT
2909 G1PPRL_ADDR_BASE_H_FORMAT
2910 G1PPRL_BYTE_H_FORMAT
2911 G1PPRL_BYTE_H_FORMAT
2912 G1PPRL_BYTE_H_FORMAT
2913 G1PPRL_DOUBLE_H_FORMAT
2914 G1PPRL_BYTE_H_FORMAT
2915 G1PPRL_STATE_H_FORMAT
2916 G1PPRL_BYTE_H_FORMAT,
2917 "type", "address-range",
2918 "used", "prev-live", "next-live", "gc-eff",
2919 "remset", "state", "code-roots");
2920 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX
2921 G1PPRL_TYPE_H_FORMAT
2922 G1PPRL_ADDR_BASE_H_FORMAT
2923 G1PPRL_BYTE_H_FORMAT
2924 G1PPRL_BYTE_H_FORMAT
2925 G1PPRL_BYTE_H_FORMAT
2926 G1PPRL_DOUBLE_H_FORMAT
2927 G1PPRL_BYTE_H_FORMAT
2928 G1PPRL_STATE_H_FORMAT
2929 G1PPRL_BYTE_H_FORMAT,
2930 "", "",
2931 "(bytes)", "(bytes)", "(bytes)", "(bytes/ms)",
2932 "(bytes)", "", "(bytes)");
2933 }
2934
2935 bool G1PrintRegionLivenessInfoClosure::do_heap_region(HeapRegion* r) {
2936 if (!log_is_enabled(Trace, gc, liveness)) {
2937 return false;
2938 }
2939
2940 const char* type = r->get_type_str();
2941 HeapWord* bottom = r->bottom();
2942 HeapWord* end = r->end();
2943 size_t capacity_bytes = r->capacity();
2944 size_t used_bytes = r->used();
2945 size_t prev_live_bytes = r->live_bytes();
2946 size_t next_live_bytes = r->next_live_bytes();
2947 double gc_eff = r->gc_efficiency();
2948 size_t remset_bytes = r->rem_set()->mem_size();
2949 size_t strong_code_roots_bytes = r->rem_set()->strong_code_roots_mem_size();
2950 const char* remset_type = r->rem_set()->get_short_state_str();
2951
2952 _total_used_bytes += used_bytes;
2953 _total_capacity_bytes += capacity_bytes;
2954 _total_prev_live_bytes += prev_live_bytes;
2955 _total_next_live_bytes += next_live_bytes;
2956 _total_remset_bytes += remset_bytes;
2957 _total_strong_code_roots_bytes += strong_code_roots_bytes;
2958
2959 // Print a line for this particular region.
2960 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX
2961 G1PPRL_TYPE_FORMAT
2962 G1PPRL_ADDR_BASE_FORMAT
2963 G1PPRL_BYTE_FORMAT
2964 G1PPRL_BYTE_FORMAT
2965 G1PPRL_BYTE_FORMAT
2966 G1PPRL_DOUBLE_FORMAT
2967 G1PPRL_BYTE_FORMAT
2968 G1PPRL_STATE_FORMAT
2969 G1PPRL_BYTE_FORMAT,
2970 type, p2i(bottom), p2i(end),
2971 used_bytes, prev_live_bytes, next_live_bytes, gc_eff,
2972 remset_bytes, remset_type, strong_code_roots_bytes);
2973
2974 return false;
2975 }
2976
2977 G1PrintRegionLivenessInfoClosure::~G1PrintRegionLivenessInfoClosure() {
2978 if (!log_is_enabled(Trace, gc, liveness)) {
2979 return;
2980 }
2981
2982 // add static memory usages to remembered set sizes
2983 _total_remset_bytes += HeapRegionRemSet::fl_mem_size() + HeapRegionRemSet::static_mem_size();
2984 // Print the footer of the output.
2985 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX);
2986 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX
2987 " SUMMARY"
2988 G1PPRL_SUM_MB_FORMAT("capacity")
2989 G1PPRL_SUM_MB_PERC_FORMAT("used")
2990 G1PPRL_SUM_MB_PERC_FORMAT("prev-live")
2991 G1PPRL_SUM_MB_PERC_FORMAT("next-live")
2992 G1PPRL_SUM_MB_FORMAT("remset")
2993 G1PPRL_SUM_MB_FORMAT("code-roots"),
2994 bytes_to_mb(_total_capacity_bytes),
2995 bytes_to_mb(_total_used_bytes),
2996 percent_of(_total_used_bytes, _total_capacity_bytes),
2997 bytes_to_mb(_total_prev_live_bytes),
2998 percent_of(_total_prev_live_bytes, _total_capacity_bytes),
2999 bytes_to_mb(_total_next_live_bytes),
3000 percent_of(_total_next_live_bytes, _total_capacity_bytes),
3001 bytes_to_mb(_total_remset_bytes),
3002 bytes_to_mb(_total_strong_code_roots_bytes));
3003 }