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 _aborted_by_fullgc(false),
389 _aborted_by_initial_mark(false),
390 _restart_for_overflow(false),
391 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
392 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()),
393
394 // _verbose_level set below
395
396 _init_times(),
397 _remark_times(),
398 _remark_mark_times(),
399 _remark_weak_ref_times(),
400 _cleanup_times(),
401 _total_cleanup_time(0.0),
402
403 _accum_task_vtime(NULL),
404
405 _concurrent_workers(NULL),
406 _num_concurrent_workers(0),
407 _max_concurrent_workers(0),
408
409 _region_mark_stats(NEW_C_HEAP_ARRAY(G1RegionMarkStats, _g1h->max_regions(), mtGC)),
410 _top_at_rebuild_starts(NEW_C_HEAP_ARRAY(HeapWord*, _g1h->max_regions(), mtGC))
411 {
412 assert(CGC_lock != NULL, "CGC_lock must be initialized");
413
414 _mark_bitmap_1.initialize(g1h->reserved_region(), prev_bitmap_storage);
415 _mark_bitmap_2.initialize(g1h->reserved_region(), next_bitmap_storage);
416
417 // Create & start ConcurrentMark thread.
418 _cm_thread = new G1ConcurrentMarkThread(this);
419 if (_cm_thread->osthread() == NULL) {
420 vm_shutdown_during_initialization("Could not create ConcurrentMarkThread");
421 }
422
423 log_debug(gc)("ConcGCThreads: %u offset %u", ConcGCThreads, _worker_id_offset);
424 log_debug(gc)("ParallelGCThreads: %u", ParallelGCThreads);
425
426 _num_concurrent_workers = ConcGCThreads;
427 _max_concurrent_workers = _num_concurrent_workers;
428
429 _concurrent_workers = new WorkGang("G1 Conc", _max_concurrent_workers, false, true);
430 _concurrent_workers->initialize_workers();
431
432 if (!_global_mark_stack.initialize(MarkStackSize, MarkStackSizeMax)) {
433 vm_exit_during_initialization("Failed to allocate initial concurrent mark overflow mark stack.");
434 }
435
436 _tasks = NEW_C_HEAP_ARRAY(G1CMTask*, _max_num_tasks, mtGC);
437 _accum_task_vtime = NEW_C_HEAP_ARRAY(double, _max_num_tasks, mtGC);
438
439 // so that the assertion in MarkingTaskQueue::task_queue doesn't fail
440 _num_active_tasks = _max_num_tasks;
441
442 for (uint i = 0; i < _max_num_tasks; ++i) {
443 G1CMTaskQueue* task_queue = new G1CMTaskQueue();
444 task_queue->initialize();
445 _task_queues->register_queue(i, task_queue);
446
447 _tasks[i] = new G1CMTask(i, this, task_queue, _region_mark_stats, _g1h->max_regions());
448
449 _accum_task_vtime[i] = 0.0;
450 }
451
452 reset_at_marking_complete();
453 }
454
455 void G1ConcurrentMark::reset() {
456 _aborted_by_fullgc = false;
457 _aborted_by_initial_mark = false;
458
459 reset_marking_for_restart();
460
461 // Reset all tasks, since different phases will use different number of active
462 // threads. So, it's easiest to have all of them ready.
463 for (uint i = 0; i < _max_num_tasks; ++i) {
464 _tasks[i]->reset(_next_mark_bitmap);
465 }
466
467 uint max_regions = _g1h->max_regions();
468 for (uint i = 0; i < max_regions; i++) {
469 _top_at_rebuild_starts[i] = NULL;
470 _region_mark_stats[i].clear();
471 }
472 }
473
474 void G1ConcurrentMark::clear_statistics_in_region(uint region_idx) {
475 for (uint j = 0; j < _max_num_tasks; ++j) {
476 _tasks[j]->clear_mark_stats_cache(region_idx);
477 }
478 _top_at_rebuild_starts[region_idx] = NULL;
479 _region_mark_stats[region_idx].clear();
480 }
481
482 void G1ConcurrentMark::clear_statistics(HeapRegion* r) {
483 uint const region_idx = r->hrm_index();
484 if (r->is_humongous()) {
485 assert(r->is_starts_humongous(), "Got humongous continues region here");
486 uint const size_in_regions = (uint)_g1h->humongous_obj_size_in_regions(oop(r->humongous_start_region()->bottom())->size());
487 for (uint j = region_idx; j < (region_idx + size_in_regions); j++) {
488 clear_statistics_in_region(j);
489 }
490 } else {
491 clear_statistics_in_region(region_idx);
492 }
493 }
494
495 static void clear_mark_if_set(G1CMBitMap* bitmap, HeapWord* addr) {
496 if (bitmap->is_marked(addr)) {
497 bitmap->clear(addr);
498 }
499 }
500
501 void G1ConcurrentMark::humongous_object_eagerly_reclaimed(HeapRegion* r) {
502 assert_at_safepoint_on_vm_thread();
503
504 // Need to clear all mark bits of the humongous object.
505 clear_mark_if_set(_prev_mark_bitmap, r->bottom());
506 clear_mark_if_set(_next_mark_bitmap, r->bottom());
507
508 if (!_g1h->collector_state()->mark_or_rebuild_in_progress()) {
509 return;
510 }
511
512 // Clear any statistics about the region gathered so far.
513 clear_statistics(r);
514 }
515
516 void G1ConcurrentMark::reset_marking_for_restart() {
517 _global_mark_stack.set_empty();
518
519 // Expand the marking stack, if we have to and if we can.
520 if (has_overflown()) {
521 _global_mark_stack.expand();
522
523 uint max_regions = _g1h->max_regions();
524 for (uint i = 0; i < max_regions; i++) {
525 _region_mark_stats[i].clear_during_overflow();
526 }
527 }
528
529 clear_has_overflown();
530 _finger = _heap.start();
531
532 for (uint i = 0; i < _max_num_tasks; ++i) {
533 G1CMTaskQueue* queue = _task_queues->queue(i);
534 queue->set_empty();
535 }
536 }
537
538 void G1ConcurrentMark::set_concurrency(uint active_tasks) {
539 assert(active_tasks <= _max_num_tasks, "we should not have more");
540
541 _num_active_tasks = active_tasks;
542 // Need to update the three data structures below according to the
543 // number of active threads for this phase.
544 _terminator.reset_for_reuse(active_tasks);
545 _first_overflow_barrier_sync.set_n_workers((int) active_tasks);
546 _second_overflow_barrier_sync.set_n_workers((int) active_tasks);
547 }
548
549 void G1ConcurrentMark::set_concurrency_and_phase(uint active_tasks, bool concurrent) {
550 set_concurrency(active_tasks);
551
552 _concurrent = concurrent;
553
554 if (!concurrent) {
555 // At this point we should be in a STW phase, and completed marking.
556 assert_at_safepoint_on_vm_thread();
557 assert(out_of_regions(),
558 "only way to get here: _finger: " PTR_FORMAT ", _heap_end: " PTR_FORMAT,
559 p2i(_finger), p2i(_heap.end()));
560 }
561 }
562
563 void G1ConcurrentMark::reset_at_marking_complete() {
564 // We set the global marking state to some default values when we're
565 // not doing marking.
566 reset_marking_for_restart();
567 _num_active_tasks = 0;
568 }
569
570 G1ConcurrentMark::~G1ConcurrentMark() {
571 FREE_C_HEAP_ARRAY(HeapWord*, _top_at_rebuild_starts);
572 FREE_C_HEAP_ARRAY(G1RegionMarkStats, _region_mark_stats);
573 // The G1ConcurrentMark instance is never freed.
574 ShouldNotReachHere();
575 }
576
577 class G1ClearBitMapTask : public AbstractGangTask {
578 public:
579 static size_t chunk_size() { return M; }
580
581 private:
582 // Heap region closure used for clearing the given mark bitmap.
583 class G1ClearBitmapHRClosure : public HeapRegionClosure {
584 private:
585 G1CMBitMap* _bitmap;
586 G1ConcurrentMark* _cm;
587 public:
588 G1ClearBitmapHRClosure(G1CMBitMap* bitmap, G1ConcurrentMark* cm) : HeapRegionClosure(), _bitmap(bitmap), _cm(cm) {
589 }
590
591 virtual bool do_heap_region(HeapRegion* r) {
592 size_t const chunk_size_in_words = G1ClearBitMapTask::chunk_size() / HeapWordSize;
593
594 HeapWord* cur = r->bottom();
595 HeapWord* const end = r->end();
596
597 while (cur < end) {
598 MemRegion mr(cur, MIN2(cur + chunk_size_in_words, end));
599 _bitmap->clear_range(mr);
600
601 cur += chunk_size_in_words;
602
603 // Abort iteration if after yielding the marking has been aborted.
604 if (_cm != NULL && _cm->do_yield_check() && _cm->has_aborted()) {
605 return true;
606 }
607 // Repeat the asserts from before the start of the closure. We will do them
608 // as asserts here to minimize their overhead on the product. However, we
609 // will have them as guarantees at the beginning / end of the bitmap
610 // clearing to get some checking in the product.
611 assert(_cm == NULL || _cm->cm_thread()->during_cycle(), "invariant");
612 assert(_cm == NULL || !G1CollectedHeap::heap()->collector_state()->mark_or_rebuild_in_progress(), "invariant");
613 }
614 assert(cur == end, "Must have completed iteration over the bitmap for region %u.", r->hrm_index());
615
616 return false;
617 }
618 };
619
620 G1ClearBitmapHRClosure _cl;
621 HeapRegionClaimer _hr_claimer;
622 bool _suspendible; // If the task is suspendible, workers must join the STS.
623
624 public:
625 G1ClearBitMapTask(G1CMBitMap* bitmap, G1ConcurrentMark* cm, uint n_workers, bool suspendible) :
626 AbstractGangTask("G1 Clear Bitmap"),
627 _cl(bitmap, suspendible ? cm : NULL),
628 _hr_claimer(n_workers),
629 _suspendible(suspendible)
630 { }
631
632 void work(uint worker_id) {
633 SuspendibleThreadSetJoiner sts_join(_suspendible);
634 G1CollectedHeap::heap()->heap_region_par_iterate_from_worker_offset(&_cl, &_hr_claimer, worker_id);
635 }
636
637 bool is_complete() {
638 return _cl.is_complete();
639 }
640 };
641
642 void G1ConcurrentMark::clear_bitmap(G1CMBitMap* bitmap, WorkGang* workers, bool may_yield) {
643 assert(may_yield || SafepointSynchronize::is_at_safepoint(), "Non-yielding bitmap clear only allowed at safepoint.");
644
645 size_t const num_bytes_to_clear = (HeapRegion::GrainBytes * _g1h->num_regions()) / G1CMBitMap::heap_map_factor();
646 size_t const num_chunks = align_up(num_bytes_to_clear, G1ClearBitMapTask::chunk_size()) / G1ClearBitMapTask::chunk_size();
647
648 uint const num_workers = (uint)MIN2(num_chunks, (size_t)workers->active_workers());
649
650 G1ClearBitMapTask cl(bitmap, this, num_workers, may_yield);
651
652 log_debug(gc, ergo)("Running %s with %u workers for " SIZE_FORMAT " work units.", cl.name(), num_workers, num_chunks);
653 workers->run_task(&cl, num_workers);
654 guarantee(!may_yield || cl.is_complete(), "Must have completed iteration when not yielding.");
655 }
656
657 void G1ConcurrentMark::cleanup_for_next_mark() {
658 // Make sure that the concurrent mark thread looks to still be in
659 // the current cycle.
660 guarantee(cm_thread()->during_cycle(), "invariant");
661
662 // We are finishing up the current cycle by clearing the next
663 // marking bitmap and getting it ready for the next cycle. During
664 // this time no other cycle can start. So, let's make sure that this
665 // is the case.
666 guarantee(!_g1h->collector_state()->mark_or_rebuild_in_progress(), "invariant");
667
668 clear_bitmap(_next_mark_bitmap, _concurrent_workers, true);
669
670 // Repeat the asserts from above.
671 guarantee(cm_thread()->during_cycle(), "invariant");
672 guarantee(!_g1h->collector_state()->mark_or_rebuild_in_progress(), "invariant");
673 }
674
675 void G1ConcurrentMark::clear_prev_bitmap(WorkGang* workers) {
676 assert_at_safepoint_on_vm_thread();
677 clear_bitmap(_prev_mark_bitmap, workers, false);
678 }
679
680 class NoteStartOfMarkHRClosure : public HeapRegionClosure {
681 public:
682 bool do_heap_region(HeapRegion* r) {
683 r->note_start_of_marking();
684 return false;
685 }
686 };
687
688 void G1ConcurrentMark::pre_initial_mark() {
689 assert_at_safepoint_on_vm_thread();
690
691 // Reset marking state.
692 reset();
693
694 // For each region note start of marking.
695 NoteStartOfMarkHRClosure startcl;
696 _g1h->heap_region_iterate(&startcl);
697
698 _root_regions.reset();
699 }
700
701
702 void G1ConcurrentMark::post_initial_mark() {
703 // Start Concurrent Marking weak-reference discovery.
704 ReferenceProcessor* rp = _g1h->ref_processor_cm();
705 // enable ("weak") refs discovery
706 rp->enable_discovery();
707 rp->setup_policy(false); // snapshot the soft ref policy to be used in this cycle
708
709 SATBMarkQueueSet& satb_mq_set = G1BarrierSet::satb_mark_queue_set();
710 // This is the start of the marking cycle, we're expected all
711 // threads to have SATB queues with active set to false.
712 satb_mq_set.set_active_all_threads(true, /* new active value */
713 false /* expected_active */);
714
715 _root_regions.prepare_for_scan();
716
717 // update_g1_committed() will be called at the end of an evac pause
718 // when marking is on. So, it's also called at the end of the
719 // initial-mark pause to update the heap end, if the heap expands
720 // during it. No need to call it here.
721 }
722
723 /*
724 * Notice that in the next two methods, we actually leave the STS
725 * during the barrier sync and join it immediately afterwards. If we
726 * do not do this, the following deadlock can occur: one thread could
727 * be in the barrier sync code, waiting for the other thread to also
728 * sync up, whereas another one could be trying to yield, while also
729 * waiting for the other threads to sync up too.
730 *
731 * Note, however, that this code is also used during remark and in
732 * this case we should not attempt to leave / enter the STS, otherwise
733 * we'll either hit an assert (debug / fastdebug) or deadlock
734 * (product). So we should only leave / enter the STS if we are
735 * operating concurrently.
736 *
737 * Because the thread that does the sync barrier has left the STS, it
738 * is possible to be suspended for a Full GC or an evacuation pause
739 * could occur. This is actually safe, since the entering the sync
740 * barrier is one of the last things do_marking_step() does, and it
741 * doesn't manipulate any data structures afterwards.
742 */
743
744 void G1ConcurrentMark::enter_first_sync_barrier(uint worker_id) {
745 bool barrier_aborted;
746 {
747 SuspendibleThreadSetLeaver sts_leave(concurrent());
748 barrier_aborted = !_first_overflow_barrier_sync.enter();
749 }
750
751 // at this point everyone should have synced up and not be doing any
752 // more work
753
754 if (barrier_aborted) {
755 // If the barrier aborted we ignore the overflow condition and
756 // just abort the whole marking phase as quickly as possible.
757 return;
758 }
759 }
760
761 void G1ConcurrentMark::enter_second_sync_barrier(uint worker_id) {
762 SuspendibleThreadSetLeaver sts_leave(concurrent());
763 _second_overflow_barrier_sync.enter();
764
765 // at this point everything should be re-initialized and ready to go
766 }
767
768 class G1CMConcurrentMarkingTask : public AbstractGangTask {
769 G1ConcurrentMark* _cm;
770
771 public:
772 void work(uint worker_id) {
773 assert(Thread::current()->is_ConcurrentGC_thread(), "Not a concurrent GC thread");
774 ResourceMark rm;
775
776 double start_vtime = os::elapsedVTime();
777
778 {
779 SuspendibleThreadSetJoiner sts_join;
780
781 assert(worker_id < _cm->active_tasks(), "invariant");
782
783 G1CMTask* task = _cm->task(worker_id);
784 task->record_start_time();
785 if (!_cm->has_aborted()) {
786 do {
787 task->do_marking_step(G1ConcMarkStepDurationMillis,
788 true /* do_termination */,
789 false /* is_serial*/);
790
791 _cm->do_yield_check();
792 } while (!_cm->has_aborted() && task->has_aborted());
793 }
794 task->record_end_time();
795 guarantee(!task->has_aborted() || _cm->has_aborted(), "invariant");
796 }
797
798 double end_vtime = os::elapsedVTime();
799 _cm->update_accum_task_vtime(worker_id, end_vtime - start_vtime);
800 }
801
802 G1CMConcurrentMarkingTask(G1ConcurrentMark* cm) :
803 AbstractGangTask("Concurrent Mark"), _cm(cm) { }
804
805 ~G1CMConcurrentMarkingTask() { }
806 };
807
808 uint G1ConcurrentMark::calc_active_marking_workers() {
809 uint result = 0;
810 if (!UseDynamicNumberOfGCThreads || !FLAG_IS_DEFAULT(ConcGCThreads)) {
811 result = _max_concurrent_workers;
812 } else {
813 result =
814 WorkerPolicy::calc_default_active_workers(_max_concurrent_workers,
815 1, /* Minimum workers */
816 _num_concurrent_workers,
817 Threads::number_of_non_daemon_threads());
818 // Don't scale the result down by scale_concurrent_workers() because
819 // that scaling has already gone into "_max_concurrent_workers".
820 }
821 assert(result > 0 && result <= _max_concurrent_workers,
822 "Calculated number of marking workers must be larger than zero and at most the maximum %u, but is %u",
823 _max_concurrent_workers, result);
824 return result;
825 }
826
827 void G1ConcurrentMark::scan_root_region(const MemRegion* region, uint worker_id) {
828 #ifdef ASSERT
829 HeapWord* last = region->last();
830 HeapRegion* hr = _g1h->heap_region_containing(last);
831 assert(hr->is_old() || hr->next_top_at_mark_start() == hr->bottom(),
832 "Root regions must be old or survivor/eden but region %u is %s", hr->hrm_index(), hr->get_type_str());
833 assert(hr->next_top_at_mark_start() == region->start(),
834 "MemRegion start should be equal to nTAMS");
835 #endif
836
837 G1RootRegionScanClosure cl(_g1h, this, worker_id);
838
839 const uintx interval = PrefetchScanIntervalInBytes;
840 HeapWord* curr = region->start();
841 const HeapWord* end = region->end();
842 while (curr < end) {
843 Prefetch::read(curr, interval);
844 oop obj = oop(curr);
845 int size = obj->oop_iterate_size(&cl);
846 assert(size == obj->size(), "sanity");
847 curr += size;
848 }
849 }
850
851 class G1CMRootRegionScanTask : public AbstractGangTask {
852 G1ConcurrentMark* _cm;
853 public:
854 G1CMRootRegionScanTask(G1ConcurrentMark* cm) :
855 AbstractGangTask("G1 Root Region Scan"), _cm(cm) { }
856
857 void work(uint worker_id) {
858 assert(Thread::current()->is_ConcurrentGC_thread(),
859 "this should only be done by a conc GC thread");
860
861 G1CMRootMemRegions* root_regions = _cm->root_regions();
862 const MemRegion* region = root_regions->claim_next();
863 while (region != NULL) {
864 _cm->scan_root_region(region, worker_id);
865 region = root_regions->claim_next();
866 }
867 }
868 };
869
870 void G1ConcurrentMark::scan_root_regions() {
871 // scan_in_progress() will have been set to true only if there was
872 // at least one root region to scan. So, if it's false, we
873 // should not attempt to do any further work.
874 if (root_regions()->scan_in_progress()) {
875 assert(!has_aborted(), "Aborting before root region scanning is finished not supported.");
876
877 _num_concurrent_workers = MIN2(calc_active_marking_workers(),
878 // We distribute work on a per-region basis, so starting
879 // more threads than that is useless.
880 root_regions()->num_root_regions());
881 assert(_num_concurrent_workers <= _max_concurrent_workers,
882 "Maximum number of marking threads exceeded");
883
884 G1CMRootRegionScanTask task(this);
885 log_debug(gc, ergo)("Running %s using %u workers for %u work units.",
886 task.name(), _num_concurrent_workers, root_regions()->num_root_regions());
887 _concurrent_workers->run_task(&task, _num_concurrent_workers);
888
889 // It's possible that has_aborted() is true here without actually
890 // aborting the survivor scan earlier. This is OK as it's
891 // mainly used for sanity checking.
892 root_regions()->scan_finished();
893 }
894 }
895
896 void G1ConcurrentMark::concurrent_cycle_start() {
897 _gc_timer_cm->register_gc_start();
898
899 _gc_tracer_cm->report_gc_start(GCCause::_no_gc /* first parameter is not used */, _gc_timer_cm->gc_start());
900
901 _g1h->trace_heap_before_gc(_gc_tracer_cm);
902 }
903
904 void G1ConcurrentMark::concurrent_cycle_end() {
905 _g1h->collector_state()->set_clearing_next_bitmap(false);
906
907 _g1h->trace_heap_after_gc(_gc_tracer_cm);
908
909 if (aborted_by_fullgc()) {
910 log_info(gc, marking)("Concurrent Mark Abort due to Full GC");
911 _gc_tracer_cm->report_concurrent_mode_failure();
912 } else if (aborted_by_initial_mark()) {
913 log_info(gc, marking)("Concurrent Mark Abort due to Humongous Reclaim");
914 }
915
916 _gc_timer_cm->register_gc_end();
917
918 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
919 }
920
921 void G1ConcurrentMark::mark_from_roots() {
922 _restart_for_overflow = false;
923
924 _num_concurrent_workers = calc_active_marking_workers();
925
926 uint active_workers = MAX2(1U, _num_concurrent_workers);
927
928 // Setting active workers is not guaranteed since fewer
929 // worker threads may currently exist and more may not be
930 // available.
931 active_workers = _concurrent_workers->update_active_workers(active_workers);
932 log_info(gc, task)("Using %u workers of %u for marking", active_workers, _concurrent_workers->total_workers());
933
934 // Parallel task terminator is set in "set_concurrency_and_phase()"
935 set_concurrency_and_phase(active_workers, true /* concurrent */);
936
937 G1CMConcurrentMarkingTask marking_task(this);
938 _concurrent_workers->run_task(&marking_task);
939 print_stats();
940 }
941
942 void G1ConcurrentMark::verify_during_pause(G1HeapVerifier::G1VerifyType type, VerifyOption vo, const char* caller) {
943 G1HeapVerifier* verifier = _g1h->verifier();
944
945 verifier->verify_region_sets_optional();
946
947 if (VerifyDuringGC) {
948 GCTraceTime(Debug, gc, phases) debug(caller, _gc_timer_cm);
949
950 size_t const BufLen = 512;
951 char buffer[BufLen];
952
953 jio_snprintf(buffer, BufLen, "During GC (%s)", caller);
954 verifier->verify(type, vo, buffer);
955 }
956
957 verifier->check_bitmaps(caller);
958 }
959
960 class G1UpdateRemSetTrackingBeforeRebuildTask : public AbstractGangTask {
961 G1CollectedHeap* _g1h;
962 G1ConcurrentMark* _cm;
963 HeapRegionClaimer _hrclaimer;
964 uint volatile _total_selected_for_rebuild;
965
966 G1PrintRegionLivenessInfoClosure _cl;
967
968 class G1UpdateRemSetTrackingBeforeRebuild : public HeapRegionClosure {
969 G1CollectedHeap* _g1h;
970 G1ConcurrentMark* _cm;
971
972 G1PrintRegionLivenessInfoClosure* _cl;
973
974 uint _num_regions_selected_for_rebuild; // The number of regions actually selected for rebuild.
975
976 void update_remset_before_rebuild(HeapRegion* hr) {
977 G1RemSetTrackingPolicy* tracking_policy = _g1h->policy()->remset_tracker();
978
979 bool selected_for_rebuild;
980 if (hr->is_humongous()) {
981 bool const is_live = _cm->liveness(hr->humongous_start_region()->hrm_index()) > 0;
982 selected_for_rebuild = tracking_policy->update_humongous_before_rebuild(hr, is_live);
983 } else {
984 size_t const live_bytes = _cm->liveness(hr->hrm_index());
985 selected_for_rebuild = tracking_policy->update_before_rebuild(hr, live_bytes);
986 }
987 if (selected_for_rebuild) {
988 _num_regions_selected_for_rebuild++;
989 }
990 _cm->update_top_at_rebuild_start(hr);
991 }
992
993 // Distribute the given words across the humongous object starting with hr and
994 // note end of marking.
995 void distribute_marked_bytes(HeapRegion* hr, size_t marked_words) {
996 uint const region_idx = hr->hrm_index();
997 size_t const obj_size_in_words = (size_t)oop(hr->bottom())->size();
998 uint const num_regions_in_humongous = (uint)G1CollectedHeap::humongous_obj_size_in_regions(obj_size_in_words);
999
1000 // "Distributing" zero words means that we only note end of marking for these
1001 // regions.
1002 assert(marked_words == 0 || obj_size_in_words == marked_words,
1003 "Marked words should either be 0 or the same as humongous object (" SIZE_FORMAT ") but is " SIZE_FORMAT,
1004 obj_size_in_words, marked_words);
1005
1006 for (uint i = region_idx; i < (region_idx + num_regions_in_humongous); i++) {
1007 HeapRegion* const r = _g1h->region_at(i);
1008 size_t const words_to_add = MIN2(HeapRegion::GrainWords, marked_words);
1009
1010 log_trace(gc, marking)("Adding " SIZE_FORMAT " words to humongous region %u (%s)",
1011 words_to_add, i, r->get_type_str());
1012 add_marked_bytes_and_note_end(r, words_to_add * HeapWordSize);
1013 marked_words -= words_to_add;
1014 }
1015 assert(marked_words == 0,
1016 SIZE_FORMAT " words left after distributing space across %u regions",
1017 marked_words, num_regions_in_humongous);
1018 }
1019
1020 void update_marked_bytes(HeapRegion* hr) {
1021 uint const region_idx = hr->hrm_index();
1022 size_t const marked_words = _cm->liveness(region_idx);
1023 // The marking attributes the object's size completely to the humongous starts
1024 // region. We need to distribute this value across the entire set of regions a
1025 // humongous object spans.
1026 if (hr->is_humongous()) {
1027 assert(hr->is_starts_humongous() || marked_words == 0,
1028 "Should not have marked words " SIZE_FORMAT " in non-starts humongous region %u (%s)",
1029 marked_words, region_idx, hr->get_type_str());
1030 if (hr->is_starts_humongous()) {
1031 distribute_marked_bytes(hr, marked_words);
1032 }
1033 } else {
1034 log_trace(gc, marking)("Adding " SIZE_FORMAT " words to region %u (%s)", marked_words, region_idx, hr->get_type_str());
1035 add_marked_bytes_and_note_end(hr, marked_words * HeapWordSize);
1036 }
1037 }
1038
1039 void add_marked_bytes_and_note_end(HeapRegion* hr, size_t marked_bytes) {
1040 hr->add_to_marked_bytes(marked_bytes);
1041 _cl->do_heap_region(hr);
1042 hr->note_end_of_marking();
1043 }
1044
1045 public:
1046 G1UpdateRemSetTrackingBeforeRebuild(G1CollectedHeap* g1h, G1ConcurrentMark* cm, G1PrintRegionLivenessInfoClosure* cl) :
1047 _g1h(g1h), _cm(cm), _cl(cl), _num_regions_selected_for_rebuild(0) { }
1048
1049 virtual bool do_heap_region(HeapRegion* r) {
1050 update_remset_before_rebuild(r);
1051 update_marked_bytes(r);
1052
1053 return false;
1054 }
1055
1056 uint num_selected_for_rebuild() const { return _num_regions_selected_for_rebuild; }
1057 };
1058
1059 public:
1060 G1UpdateRemSetTrackingBeforeRebuildTask(G1CollectedHeap* g1h, G1ConcurrentMark* cm, uint num_workers) :
1061 AbstractGangTask("G1 Update RemSet Tracking Before Rebuild"),
1062 _g1h(g1h), _cm(cm), _hrclaimer(num_workers), _total_selected_for_rebuild(0), _cl("Post-Marking") { }
1063
1064 virtual void work(uint worker_id) {
1065 G1UpdateRemSetTrackingBeforeRebuild update_cl(_g1h, _cm, &_cl);
1066 _g1h->heap_region_par_iterate_from_worker_offset(&update_cl, &_hrclaimer, worker_id);
1067 Atomic::add(&_total_selected_for_rebuild, update_cl.num_selected_for_rebuild());
1068 }
1069
1070 uint total_selected_for_rebuild() const { return _total_selected_for_rebuild; }
1071
1072 // Number of regions for which roughly one thread should be spawned for this work.
1073 static const uint RegionsPerThread = 384;
1074 };
1075
1076 class G1UpdateRemSetTrackingAfterRebuild : public HeapRegionClosure {
1077 G1CollectedHeap* _g1h;
1078 public:
1079 G1UpdateRemSetTrackingAfterRebuild(G1CollectedHeap* g1h) : _g1h(g1h) { }
1080
1081 virtual bool do_heap_region(HeapRegion* r) {
1082 _g1h->policy()->remset_tracker()->update_after_rebuild(r);
1083 return false;
1084 }
1085 };
1086
1087 void G1ConcurrentMark::remark() {
1088 assert_at_safepoint_on_vm_thread();
1089
1090 // If a full collection has happened, we should not continue. However we might
1091 // have ended up here as the Remark VM operation has been scheduled already.
1092 if (has_aborted()) {
1093 return;
1094 }
1095
1096 G1Policy* policy = _g1h->policy();
1097 policy->record_concurrent_mark_remark_start();
1098
1099 double start = os::elapsedTime();
1100
1101 verify_during_pause(G1HeapVerifier::G1VerifyRemark, VerifyOption_G1UsePrevMarking, "Remark before");
1102
1103 {
1104 GCTraceTime(Debug, gc, phases) debug("Finalize Marking", _gc_timer_cm);
1105 finalize_marking();
1106 }
1107
1108 double mark_work_end = os::elapsedTime();
1109
1110 bool const mark_finished = !has_overflown();
1111 if (mark_finished) {
1112 weak_refs_work(false /* clear_all_soft_refs */);
1113
1114 SATBMarkQueueSet& satb_mq_set = G1BarrierSet::satb_mark_queue_set();
1115 // We're done with marking.
1116 // This is the end of the marking cycle, we're expected all
1117 // threads to have SATB queues with active set to true.
1118 satb_mq_set.set_active_all_threads(false, /* new active value */
1119 true /* expected_active */);
1120
1121 {
1122 GCTraceTime(Debug, gc, phases) debug("Flush Task Caches", _gc_timer_cm);
1123 flush_all_task_caches();
1124 }
1125
1126 // Install newly created mark bitmap as "prev".
1127 swap_mark_bitmaps();
1128 {
1129 GCTraceTime(Debug, gc, phases) debug("Update Remembered Set Tracking Before Rebuild", _gc_timer_cm);
1130
1131 uint const workers_by_capacity = (_g1h->num_regions() + G1UpdateRemSetTrackingBeforeRebuildTask::RegionsPerThread - 1) /
1132 G1UpdateRemSetTrackingBeforeRebuildTask::RegionsPerThread;
1133 uint const num_workers = MIN2(_g1h->workers()->active_workers(), workers_by_capacity);
1134
1135 G1UpdateRemSetTrackingBeforeRebuildTask cl(_g1h, this, num_workers);
1136 log_debug(gc,ergo)("Running %s using %u workers for %u regions in heap", cl.name(), num_workers, _g1h->num_regions());
1137 _g1h->workers()->run_task(&cl, num_workers);
1138
1139 log_debug(gc, remset, tracking)("Remembered Set Tracking update regions total %u, selected %u",
1140 _g1h->num_regions(), cl.total_selected_for_rebuild());
1141 }
1142 {
1143 GCTraceTime(Debug, gc, phases) debug("Reclaim Empty Regions", _gc_timer_cm);
1144 reclaim_empty_regions();
1145 }
1146
1147 // Clean out dead classes
1148 if (ClassUnloadingWithConcurrentMark) {
1149 GCTraceTime(Debug, gc, phases) debug("Purge Metaspace", _gc_timer_cm);
1150 ClassLoaderDataGraph::purge();
1151 }
1152
1153 _g1h->resize_heap_if_necessary();
1154
1155 compute_new_sizes();
1156
1157 verify_during_pause(G1HeapVerifier::G1VerifyRemark, VerifyOption_G1UsePrevMarking, "Remark after");
1158
1159 assert(!restart_for_overflow(), "sanity");
1160 // Completely reset the marking state since marking completed
1161 reset_at_marking_complete();
1162 } else {
1163 // We overflowed. Restart concurrent marking.
1164 _restart_for_overflow = true;
1165
1166 verify_during_pause(G1HeapVerifier::G1VerifyRemark, VerifyOption_G1UsePrevMarking, "Remark overflow");
1167
1168 // Clear the marking state because we will be restarting
1169 // marking due to overflowing the global mark stack.
1170 reset_marking_for_restart();
1171 }
1172
1173 {
1174 GCTraceTime(Debug, gc, phases) debug("Report Object Count", _gc_timer_cm);
1175 report_object_count(mark_finished);
1176 }
1177
1178 // Statistics
1179 double now = os::elapsedTime();
1180 _remark_mark_times.add((mark_work_end - start) * 1000.0);
1181 _remark_weak_ref_times.add((now - mark_work_end) * 1000.0);
1182 _remark_times.add((now - start) * 1000.0);
1183
1184 policy->record_concurrent_mark_remark_end();
1185 }
1186
1187 class G1ReclaimEmptyRegionsTask : public AbstractGangTask {
1188 // Per-region work during the Cleanup pause.
1189 class G1ReclaimEmptyRegionsClosure : public HeapRegionClosure {
1190 G1CollectedHeap* _g1h;
1191 size_t _freed_bytes;
1192 FreeRegionList* _local_cleanup_list;
1193 uint _old_regions_removed;
1194 uint _humongous_regions_removed;
1195
1196 public:
1197 G1ReclaimEmptyRegionsClosure(G1CollectedHeap* g1h,
1198 FreeRegionList* local_cleanup_list) :
1199 _g1h(g1h),
1200 _freed_bytes(0),
1201 _local_cleanup_list(local_cleanup_list),
1202 _old_regions_removed(0),
1203 _humongous_regions_removed(0) { }
1204
1205 size_t freed_bytes() { return _freed_bytes; }
1206 const uint old_regions_removed() { return _old_regions_removed; }
1207 const uint humongous_regions_removed() { return _humongous_regions_removed; }
1208
1209 bool do_heap_region(HeapRegion *hr) {
1210 if (hr->used() > 0 && hr->max_live_bytes() == 0 && !hr->is_young() && !hr->is_archive()) {
1211 _freed_bytes += hr->used();
1212 hr->set_containing_set(NULL);
1213 if (hr->is_humongous()) {
1214 _humongous_regions_removed++;
1215 _g1h->free_humongous_region(hr, _local_cleanup_list);
1216 } else {
1217 _old_regions_removed++;
1218 _g1h->free_region(hr, _local_cleanup_list);
1219 }
1220 hr->clear_cardtable();
1221 _g1h->concurrent_mark()->clear_statistics_in_region(hr->hrm_index());
1222 log_trace(gc)("Reclaimed empty region %u (%s) bot " PTR_FORMAT, hr->hrm_index(), hr->get_short_type_str(), p2i(hr->bottom()));
1223 }
1224
1225 return false;
1226 }
1227 };
1228
1229 G1CollectedHeap* _g1h;
1230 FreeRegionList* _cleanup_list;
1231 HeapRegionClaimer _hrclaimer;
1232
1233 public:
1234 G1ReclaimEmptyRegionsTask(G1CollectedHeap* g1h, FreeRegionList* cleanup_list, uint n_workers) :
1235 AbstractGangTask("G1 Cleanup"),
1236 _g1h(g1h),
1237 _cleanup_list(cleanup_list),
1238 _hrclaimer(n_workers) {
1239 }
1240
1241 void work(uint worker_id) {
1242 FreeRegionList local_cleanup_list("Local Cleanup List");
1243 G1ReclaimEmptyRegionsClosure cl(_g1h, &local_cleanup_list);
1244 _g1h->heap_region_par_iterate_from_worker_offset(&cl, &_hrclaimer, worker_id);
1245 assert(cl.is_complete(), "Shouldn't have aborted!");
1246
1247 // Now update the old/humongous region sets
1248 _g1h->remove_from_old_sets(cl.old_regions_removed(), cl.humongous_regions_removed());
1249 {
1250 MutexLocker x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
1251 _g1h->decrement_summary_bytes(cl.freed_bytes());
1252
1253 _cleanup_list->add_ordered(&local_cleanup_list);
1254 assert(local_cleanup_list.is_empty(), "post-condition");
1255 }
1256 }
1257 };
1258
1259 void G1ConcurrentMark::reclaim_empty_regions() {
1260 WorkGang* workers = _g1h->workers();
1261 FreeRegionList empty_regions_list("Empty Regions After Mark List");
1262
1263 G1ReclaimEmptyRegionsTask cl(_g1h, &empty_regions_list, workers->active_workers());
1264 workers->run_task(&cl);
1265
1266 if (!empty_regions_list.is_empty()) {
1267 log_debug(gc)("Reclaimed %u empty regions", empty_regions_list.length());
1268 // Now print the empty regions list.
1269 G1HRPrinter* hrp = _g1h->hr_printer();
1270 if (hrp->is_active()) {
1271 FreeRegionListIterator iter(&empty_regions_list);
1272 while (iter.more_available()) {
1273 HeapRegion* hr = iter.get_next();
1274 hrp->cleanup(hr);
1275 }
1276 }
1277 // And actually make them available.
1278 _g1h->prepend_to_freelist(&empty_regions_list);
1279 }
1280 }
1281
1282 void G1ConcurrentMark::compute_new_sizes() {
1283 MetaspaceGC::compute_new_size();
1284
1285 // Cleanup will have freed any regions completely full of garbage.
1286 // Update the soft reference policy with the new heap occupancy.
1287 Universe::update_heap_info_at_gc();
1288
1289 // We reclaimed old regions so we should calculate the sizes to make
1290 // sure we update the old gen/space data.
1291 _g1h->g1mm()->update_sizes();
1292 }
1293
1294 void G1ConcurrentMark::cleanup() {
1295 assert_at_safepoint_on_vm_thread();
1296
1297 // If a full collection has happened, we shouldn't do this.
1298 if (has_aborted()) {
1299 return;
1300 }
1301
1302 G1Policy* policy = _g1h->policy();
1303 policy->record_concurrent_mark_cleanup_start();
1304
1305 double start = os::elapsedTime();
1306
1307 verify_during_pause(G1HeapVerifier::G1VerifyCleanup, VerifyOption_G1UsePrevMarking, "Cleanup before");
1308
1309 {
1310 GCTraceTime(Debug, gc, phases) debug("Update Remembered Set Tracking After Rebuild", _gc_timer_cm);
1311 G1UpdateRemSetTrackingAfterRebuild cl(_g1h);
1312 _g1h->heap_region_iterate(&cl);
1313 }
1314
1315 if (log_is_enabled(Trace, gc, liveness)) {
1316 G1PrintRegionLivenessInfoClosure cl("Post-Cleanup");
1317 _g1h->heap_region_iterate(&cl);
1318 }
1319
1320 verify_during_pause(G1HeapVerifier::G1VerifyCleanup, VerifyOption_G1UsePrevMarking, "Cleanup after");
1321
1322 // We need to make this be a "collection" so any collection pause that
1323 // races with it goes around and waits for Cleanup to finish.
1324 _g1h->increment_total_collections();
1325
1326 // Local statistics
1327 double recent_cleanup_time = (os::elapsedTime() - start);
1328 _total_cleanup_time += recent_cleanup_time;
1329 _cleanup_times.add(recent_cleanup_time);
1330
1331 {
1332 GCTraceTime(Debug, gc, phases) debug("Finalize Concurrent Mark Cleanup", _gc_timer_cm);
1333 policy->record_concurrent_mark_cleanup_end();
1334 }
1335 }
1336
1337 // 'Keep Alive' oop closure used by both serial parallel reference processing.
1338 // Uses the G1CMTask associated with a worker thread (for serial reference
1339 // processing the G1CMTask for worker 0 is used) to preserve (mark) and
1340 // trace referent objects.
1341 //
1342 // Using the G1CMTask and embedded local queues avoids having the worker
1343 // threads operating on the global mark stack. This reduces the risk
1344 // of overflowing the stack - which we would rather avoid at this late
1345 // state. Also using the tasks' local queues removes the potential
1346 // of the workers interfering with each other that could occur if
1347 // operating on the global stack.
1348
1349 class G1CMKeepAliveAndDrainClosure : public OopClosure {
1350 G1ConcurrentMark* _cm;
1351 G1CMTask* _task;
1352 uint _ref_counter_limit;
1353 uint _ref_counter;
1354 bool _is_serial;
1355 public:
1356 G1CMKeepAliveAndDrainClosure(G1ConcurrentMark* cm, G1CMTask* task, bool is_serial) :
1357 _cm(cm), _task(task), _ref_counter_limit(G1RefProcDrainInterval),
1358 _ref_counter(_ref_counter_limit), _is_serial(is_serial) {
1359 assert(!_is_serial || _task->worker_id() == 0, "only task 0 for serial code");
1360 }
1361
1362 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
1363 virtual void do_oop( oop* p) { do_oop_work(p); }
1364
1365 template <class T> void do_oop_work(T* p) {
1366 if (_cm->has_overflown()) {
1367 return;
1368 }
1369 if (!_task->deal_with_reference(p)) {
1370 // We did not add anything to the mark bitmap (or mark stack), so there is
1371 // no point trying to drain it.
1372 return;
1373 }
1374 _ref_counter--;
1375
1376 if (_ref_counter == 0) {
1377 // We have dealt with _ref_counter_limit references, pushing them
1378 // and objects reachable from them on to the local stack (and
1379 // possibly the global stack). Call G1CMTask::do_marking_step() to
1380 // process these entries.
1381 //
1382 // We call G1CMTask::do_marking_step() in a loop, which we'll exit if
1383 // there's nothing more to do (i.e. we're done with the entries that
1384 // were pushed as a result of the G1CMTask::deal_with_reference() calls
1385 // above) or we overflow.
1386 //
1387 // Note: G1CMTask::do_marking_step() can set the G1CMTask::has_aborted()
1388 // flag while there may still be some work to do. (See the comment at
1389 // the beginning of G1CMTask::do_marking_step() for those conditions -
1390 // one of which is reaching the specified time target.) It is only
1391 // when G1CMTask::do_marking_step() returns without setting the
1392 // has_aborted() flag that the marking step has completed.
1393 do {
1394 double mark_step_duration_ms = G1ConcMarkStepDurationMillis;
1395 _task->do_marking_step(mark_step_duration_ms,
1396 false /* do_termination */,
1397 _is_serial);
1398 } while (_task->has_aborted() && !_cm->has_overflown());
1399 _ref_counter = _ref_counter_limit;
1400 }
1401 }
1402 };
1403
1404 // 'Drain' oop closure used by both serial and parallel reference processing.
1405 // Uses the G1CMTask associated with a given worker thread (for serial
1406 // reference processing the G1CMtask for worker 0 is used). Calls the
1407 // do_marking_step routine, with an unbelievably large timeout value,
1408 // to drain the marking data structures of the remaining entries
1409 // added by the 'keep alive' oop closure above.
1410
1411 class G1CMDrainMarkingStackClosure : public VoidClosure {
1412 G1ConcurrentMark* _cm;
1413 G1CMTask* _task;
1414 bool _is_serial;
1415 public:
1416 G1CMDrainMarkingStackClosure(G1ConcurrentMark* cm, G1CMTask* task, bool is_serial) :
1417 _cm(cm), _task(task), _is_serial(is_serial) {
1418 assert(!_is_serial || _task->worker_id() == 0, "only task 0 for serial code");
1419 }
1420
1421 void do_void() {
1422 do {
1423 // We call G1CMTask::do_marking_step() to completely drain the local
1424 // and global marking stacks of entries pushed by the 'keep alive'
1425 // oop closure (an instance of G1CMKeepAliveAndDrainClosure above).
1426 //
1427 // G1CMTask::do_marking_step() is called in a loop, which we'll exit
1428 // if there's nothing more to do (i.e. we've completely drained the
1429 // entries that were pushed as a a result of applying the 'keep alive'
1430 // closure to the entries on the discovered ref lists) or we overflow
1431 // the global marking stack.
1432 //
1433 // Note: G1CMTask::do_marking_step() can set the G1CMTask::has_aborted()
1434 // flag while there may still be some work to do. (See the comment at
1435 // the beginning of G1CMTask::do_marking_step() for those conditions -
1436 // one of which is reaching the specified time target.) It is only
1437 // when G1CMTask::do_marking_step() returns without setting the
1438 // has_aborted() flag that the marking step has completed.
1439
1440 _task->do_marking_step(1000000000.0 /* something very large */,
1441 true /* do_termination */,
1442 _is_serial);
1443 } while (_task->has_aborted() && !_cm->has_overflown());
1444 }
1445 };
1446
1447 // Implementation of AbstractRefProcTaskExecutor for parallel
1448 // reference processing at the end of G1 concurrent marking
1449
1450 class G1CMRefProcTaskExecutor : public AbstractRefProcTaskExecutor {
1451 private:
1452 G1CollectedHeap* _g1h;
1453 G1ConcurrentMark* _cm;
1454 WorkGang* _workers;
1455 uint _active_workers;
1456
1457 public:
1458 G1CMRefProcTaskExecutor(G1CollectedHeap* g1h,
1459 G1ConcurrentMark* cm,
1460 WorkGang* workers,
1461 uint n_workers) :
1462 _g1h(g1h), _cm(cm),
1463 _workers(workers), _active_workers(n_workers) { }
1464
1465 virtual void execute(ProcessTask& task, uint ergo_workers);
1466 };
1467
1468 class G1CMRefProcTaskProxy : public AbstractGangTask {
1469 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
1470 ProcessTask& _proc_task;
1471 G1CollectedHeap* _g1h;
1472 G1ConcurrentMark* _cm;
1473
1474 public:
1475 G1CMRefProcTaskProxy(ProcessTask& proc_task,
1476 G1CollectedHeap* g1h,
1477 G1ConcurrentMark* cm) :
1478 AbstractGangTask("Process reference objects in parallel"),
1479 _proc_task(proc_task), _g1h(g1h), _cm(cm) {
1480 ReferenceProcessor* rp = _g1h->ref_processor_cm();
1481 assert(rp->processing_is_mt(), "shouldn't be here otherwise");
1482 }
1483
1484 virtual void work(uint worker_id) {
1485 ResourceMark rm;
1486 HandleMark hm;
1487 G1CMTask* task = _cm->task(worker_id);
1488 G1CMIsAliveClosure g1_is_alive(_g1h);
1489 G1CMKeepAliveAndDrainClosure g1_par_keep_alive(_cm, task, false /* is_serial */);
1490 G1CMDrainMarkingStackClosure g1_par_drain(_cm, task, false /* is_serial */);
1491
1492 _proc_task.work(worker_id, g1_is_alive, g1_par_keep_alive, g1_par_drain);
1493 }
1494 };
1495
1496 void G1CMRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) {
1497 assert(_workers != NULL, "Need parallel worker threads.");
1498 assert(_g1h->ref_processor_cm()->processing_is_mt(), "processing is not MT");
1499 assert(_workers->active_workers() >= ergo_workers,
1500 "Ergonomically chosen workers(%u) should be less than or equal to active workers(%u)",
1501 ergo_workers, _workers->active_workers());
1502
1503 G1CMRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _cm);
1504
1505 // We need to reset the concurrency level before each
1506 // proxy task execution, so that the termination protocol
1507 // and overflow handling in G1CMTask::do_marking_step() knows
1508 // how many workers to wait for.
1509 _cm->set_concurrency(ergo_workers);
1510 _workers->run_task(&proc_task_proxy, ergo_workers);
1511 }
1512
1513 void G1ConcurrentMark::weak_refs_work(bool clear_all_soft_refs) {
1514 ResourceMark rm;
1515 HandleMark hm;
1516
1517 // Is alive closure.
1518 G1CMIsAliveClosure g1_is_alive(_g1h);
1519
1520 // Inner scope to exclude the cleaning of the string table
1521 // from the displayed time.
1522 {
1523 GCTraceTime(Debug, gc, phases) debug("Reference Processing", _gc_timer_cm);
1524
1525 ReferenceProcessor* rp = _g1h->ref_processor_cm();
1526
1527 // See the comment in G1CollectedHeap::ref_processing_init()
1528 // about how reference processing currently works in G1.
1529
1530 // Set the soft reference policy
1531 rp->setup_policy(clear_all_soft_refs);
1532 assert(_global_mark_stack.is_empty(), "mark stack should be empty");
1533
1534 // Instances of the 'Keep Alive' and 'Complete GC' closures used
1535 // in serial reference processing. Note these closures are also
1536 // used for serially processing (by the the current thread) the
1537 // JNI references during parallel reference processing.
1538 //
1539 // These closures do not need to synchronize with the worker
1540 // threads involved in parallel reference processing as these
1541 // instances are executed serially by the current thread (e.g.
1542 // reference processing is not multi-threaded and is thus
1543 // performed by the current thread instead of a gang worker).
1544 //
1545 // The gang tasks involved in parallel reference processing create
1546 // their own instances of these closures, which do their own
1547 // synchronization among themselves.
1548 G1CMKeepAliveAndDrainClosure g1_keep_alive(this, task(0), true /* is_serial */);
1549 G1CMDrainMarkingStackClosure g1_drain_mark_stack(this, task(0), true /* is_serial */);
1550
1551 // We need at least one active thread. If reference processing
1552 // is not multi-threaded we use the current (VMThread) thread,
1553 // otherwise we use the work gang from the G1CollectedHeap and
1554 // we utilize all the worker threads we can.
1555 bool processing_is_mt = rp->processing_is_mt();
1556 uint active_workers = (processing_is_mt ? _g1h->workers()->active_workers() : 1U);
1557 active_workers = clamp(active_workers, 1u, _max_num_tasks);
1558
1559 // Parallel processing task executor.
1560 G1CMRefProcTaskExecutor par_task_executor(_g1h, this,
1561 _g1h->workers(), active_workers);
1562 AbstractRefProcTaskExecutor* executor = (processing_is_mt ? &par_task_executor : NULL);
1563
1564 // Set the concurrency level. The phase was already set prior to
1565 // executing the remark task.
1566 set_concurrency(active_workers);
1567
1568 // Set the degree of MT processing here. If the discovery was done MT,
1569 // the number of threads involved during discovery could differ from
1570 // the number of active workers. This is OK as long as the discovered
1571 // Reference lists are balanced (see balance_all_queues() and balance_queues()).
1572 rp->set_active_mt_degree(active_workers);
1573
1574 ReferenceProcessorPhaseTimes pt(_gc_timer_cm, rp->max_num_queues());
1575
1576 // Process the weak references.
1577 const ReferenceProcessorStats& stats =
1578 rp->process_discovered_references(&g1_is_alive,
1579 &g1_keep_alive,
1580 &g1_drain_mark_stack,
1581 executor,
1582 &pt);
1583 _gc_tracer_cm->report_gc_reference_stats(stats);
1584 pt.print_all_references();
1585
1586 // The do_oop work routines of the keep_alive and drain_marking_stack
1587 // oop closures will set the has_overflown flag if we overflow the
1588 // global marking stack.
1589
1590 assert(has_overflown() || _global_mark_stack.is_empty(),
1591 "Mark stack should be empty (unless it has overflown)");
1592
1593 assert(rp->num_queues() == active_workers, "why not");
1594
1595 rp->verify_no_references_recorded();
1596 assert(!rp->discovery_enabled(), "Post condition");
1597 }
1598
1599 if (has_overflown()) {
1600 // We can not trust g1_is_alive and the contents of the heap if the marking stack
1601 // overflowed while processing references. Exit the VM.
1602 fatal("Overflow during reference processing, can not continue. Please "
1603 "increase MarkStackSizeMax (current value: " SIZE_FORMAT ") and "
1604 "restart.", MarkStackSizeMax);
1605 return;
1606 }
1607
1608 assert(_global_mark_stack.is_empty(), "Marking should have completed");
1609
1610 {
1611 GCTraceTime(Debug, gc, phases) debug("Weak Processing", _gc_timer_cm);
1612 WeakProcessor::weak_oops_do(_g1h->workers(), &g1_is_alive, &do_nothing_cl, 1);
1613 }
1614
1615 // Unload Klasses, String, Code Cache, etc.
1616 if (ClassUnloadingWithConcurrentMark) {
1617 GCTraceTime(Debug, gc, phases) debug("Class Unloading", _gc_timer_cm);
1618 bool purged_classes = SystemDictionary::do_unloading(_gc_timer_cm);
1619 _g1h->complete_cleaning(&g1_is_alive, purged_classes);
1620 } else if (StringDedup::is_enabled()) {
1621 GCTraceTime(Debug, gc, phases) debug("String Deduplication", _gc_timer_cm);
1622 _g1h->string_dedup_cleaning(&g1_is_alive, NULL);
1623 }
1624 }
1625
1626 class G1PrecleanYieldClosure : public YieldClosure {
1627 G1ConcurrentMark* _cm;
1628
1629 public:
1630 G1PrecleanYieldClosure(G1ConcurrentMark* cm) : _cm(cm) { }
1631
1632 virtual bool should_return() {
1633 return _cm->has_aborted();
1634 }
1635
1636 virtual bool should_return_fine_grain() {
1637 _cm->do_yield_check();
1638 return _cm->has_aborted();
1639 }
1640 };
1641
1642 void G1ConcurrentMark::preclean() {
1643 assert(G1UseReferencePrecleaning, "Precleaning must be enabled.");
1644
1645 SuspendibleThreadSetJoiner joiner;
1646
1647 G1CMKeepAliveAndDrainClosure keep_alive(this, task(0), true /* is_serial */);
1648 G1CMDrainMarkingStackClosure drain_mark_stack(this, task(0), true /* is_serial */);
1649
1650 set_concurrency_and_phase(1, true);
1651
1652 G1PrecleanYieldClosure yield_cl(this);
1653
1654 ReferenceProcessor* rp = _g1h->ref_processor_cm();
1655 // Precleaning is single threaded. Temporarily disable MT discovery.
1656 ReferenceProcessorMTDiscoveryMutator rp_mut_discovery(rp, false);
1657 rp->preclean_discovered_references(rp->is_alive_non_header(),
1658 &keep_alive,
1659 &drain_mark_stack,
1660 &yield_cl,
1661 _gc_timer_cm);
1662 }
1663
1664 // When sampling object counts, we already swapped the mark bitmaps, so we need to use
1665 // the prev bitmap determining liveness.
1666 class G1ObjectCountIsAliveClosure: public BoolObjectClosure {
1667 G1CollectedHeap* _g1h;
1668 public:
1669 G1ObjectCountIsAliveClosure(G1CollectedHeap* g1h) : _g1h(g1h) { }
1670
1671 bool do_object_b(oop obj) {
1672 return obj != NULL &&
1673 (!_g1h->is_in_g1_reserved(obj) || !_g1h->is_obj_dead(obj));
1674 }
1675 };
1676
1677 void G1ConcurrentMark::report_object_count(bool mark_completed) {
1678 // Depending on the completion of the marking liveness needs to be determined
1679 // using either the next or prev bitmap.
1680 if (mark_completed) {
1681 G1ObjectCountIsAliveClosure is_alive(_g1h);
1682 _gc_tracer_cm->report_object_count_after_gc(&is_alive);
1683 } else {
1684 G1CMIsAliveClosure is_alive(_g1h);
1685 _gc_tracer_cm->report_object_count_after_gc(&is_alive);
1686 }
1687 }
1688
1689
1690 void G1ConcurrentMark::swap_mark_bitmaps() {
1691 G1CMBitMap* temp = _prev_mark_bitmap;
1692 _prev_mark_bitmap = _next_mark_bitmap;
1693 _next_mark_bitmap = temp;
1694 _g1h->collector_state()->set_clearing_next_bitmap(true);
1695 }
1696
1697 // Closure for marking entries in SATB buffers.
1698 class G1CMSATBBufferClosure : public SATBBufferClosure {
1699 private:
1700 G1CMTask* _task;
1701 G1CollectedHeap* _g1h;
1702
1703 // This is very similar to G1CMTask::deal_with_reference, but with
1704 // more relaxed requirements for the argument, so this must be more
1705 // circumspect about treating the argument as an object.
1706 void do_entry(void* entry) const {
1707 _task->increment_refs_reached();
1708 oop const obj = static_cast<oop>(entry);
1709 _task->make_reference_grey(obj);
1710 }
1711
1712 public:
1713 G1CMSATBBufferClosure(G1CMTask* task, G1CollectedHeap* g1h)
1714 : _task(task), _g1h(g1h) { }
1715
1716 virtual void do_buffer(void** buffer, size_t size) {
1717 for (size_t i = 0; i < size; ++i) {
1718 do_entry(buffer[i]);
1719 }
1720 }
1721 };
1722
1723 class G1RemarkThreadsClosure : public ThreadClosure {
1724 G1CMSATBBufferClosure _cm_satb_cl;
1725 G1CMOopClosure _cm_cl;
1726 MarkingCodeBlobClosure _code_cl;
1727 uintx _claim_token;
1728
1729 public:
1730 G1RemarkThreadsClosure(G1CollectedHeap* g1h, G1CMTask* task) :
1731 _cm_satb_cl(task, g1h),
1732 _cm_cl(g1h, task),
1733 _code_cl(&_cm_cl, !CodeBlobToOopClosure::FixRelocations),
1734 _claim_token(Threads::thread_claim_token()) {}
1735
1736 void do_thread(Thread* thread) {
1737 if (thread->claim_threads_do(true, _claim_token)) {
1738 SATBMarkQueue& queue = G1ThreadLocalData::satb_mark_queue(thread);
1739 queue.apply_closure_and_empty(&_cm_satb_cl);
1740 if (thread->is_Java_thread()) {
1741 // In theory it should not be neccessary to explicitly walk the nmethods to find roots for concurrent marking
1742 // however the liveness of oops reachable from nmethods have very complex lifecycles:
1743 // * Alive if on the stack of an executing method
1744 // * Weakly reachable otherwise
1745 // Some objects reachable from nmethods, such as the class loader (or klass_holder) of the receiver should be
1746 // live by the SATB invariant but other oops recorded in nmethods may behave differently.
1747 JavaThread* jt = (JavaThread*)thread;
1748 jt->nmethods_do(&_code_cl);
1749 }
1750 }
1751 }
1752 };
1753
1754 class G1CMRemarkTask : public AbstractGangTask {
1755 G1ConcurrentMark* _cm;
1756 public:
1757 void work(uint worker_id) {
1758 G1CMTask* task = _cm->task(worker_id);
1759 task->record_start_time();
1760 {
1761 ResourceMark rm;
1762 HandleMark hm;
1763
1764 G1RemarkThreadsClosure threads_f(G1CollectedHeap::heap(), task);
1765 Threads::threads_do(&threads_f);
1766 }
1767
1768 do {
1769 task->do_marking_step(1000000000.0 /* something very large */,
1770 true /* do_termination */,
1771 false /* is_serial */);
1772 } while (task->has_aborted() && !_cm->has_overflown());
1773 // If we overflow, then we do not want to restart. We instead
1774 // want to abort remark and do concurrent marking again.
1775 task->record_end_time();
1776 }
1777
1778 G1CMRemarkTask(G1ConcurrentMark* cm, uint active_workers) :
1779 AbstractGangTask("Par Remark"), _cm(cm) {
1780 _cm->terminator()->reset_for_reuse(active_workers);
1781 }
1782 };
1783
1784 void G1ConcurrentMark::finalize_marking() {
1785 ResourceMark rm;
1786 HandleMark hm;
1787
1788 _g1h->ensure_parsability(false);
1789
1790 // this is remark, so we'll use up all active threads
1791 uint active_workers = _g1h->workers()->active_workers();
1792 set_concurrency_and_phase(active_workers, false /* concurrent */);
1793 // Leave _parallel_marking_threads at it's
1794 // value originally calculated in the G1ConcurrentMark
1795 // constructor and pass values of the active workers
1796 // through the gang in the task.
1797
1798 {
1799 StrongRootsScope srs(active_workers);
1800
1801 G1CMRemarkTask remarkTask(this, active_workers);
1802 // We will start all available threads, even if we decide that the
1803 // active_workers will be fewer. The extra ones will just bail out
1804 // immediately.
1805 _g1h->workers()->run_task(&remarkTask);
1806 }
1807
1808 SATBMarkQueueSet& satb_mq_set = G1BarrierSet::satb_mark_queue_set();
1809 guarantee(has_overflown() ||
1810 satb_mq_set.completed_buffers_num() == 0,
1811 "Invariant: has_overflown = %s, num buffers = " SIZE_FORMAT,
1812 BOOL_TO_STR(has_overflown()),
1813 satb_mq_set.completed_buffers_num());
1814
1815 print_stats();
1816 }
1817
1818 void G1ConcurrentMark::flush_all_task_caches() {
1819 size_t hits = 0;
1820 size_t misses = 0;
1821 for (uint i = 0; i < _max_num_tasks; i++) {
1822 Pair<size_t, size_t> stats = _tasks[i]->flush_mark_stats_cache();
1823 hits += stats.first;
1824 misses += stats.second;
1825 }
1826 size_t sum = hits + misses;
1827 log_debug(gc, stats)("Mark stats cache hits " SIZE_FORMAT " misses " SIZE_FORMAT " ratio %1.3lf",
1828 hits, misses, percent_of(hits, sum));
1829 }
1830
1831 void G1ConcurrentMark::clear_range_in_prev_bitmap(MemRegion mr) {
1832 _prev_mark_bitmap->clear_range(mr);
1833 }
1834
1835 HeapRegion*
1836 G1ConcurrentMark::claim_region(uint worker_id) {
1837 // "checkpoint" the finger
1838 HeapWord* finger = _finger;
1839
1840 while (finger < _heap.end()) {
1841 assert(_g1h->is_in_g1_reserved(finger), "invariant");
1842
1843 HeapRegion* curr_region = _g1h->heap_region_containing(finger);
1844 // Make sure that the reads below do not float before loading curr_region.
1845 OrderAccess::loadload();
1846 // Above heap_region_containing may return NULL as we always scan claim
1847 // until the end of the heap. In this case, just jump to the next region.
1848 HeapWord* end = curr_region != NULL ? curr_region->end() : finger + HeapRegion::GrainWords;
1849
1850 // Is the gap between reading the finger and doing the CAS too long?
1851 HeapWord* res = Atomic::cmpxchg(&_finger, finger, end);
1852 if (res == finger && curr_region != NULL) {
1853 // we succeeded
1854 HeapWord* bottom = curr_region->bottom();
1855 HeapWord* limit = curr_region->next_top_at_mark_start();
1856
1857 // notice that _finger == end cannot be guaranteed here since,
1858 // someone else might have moved the finger even further
1859 assert(_finger >= end, "the finger should have moved forward");
1860
1861 if (limit > bottom) {
1862 return curr_region;
1863 } else {
1864 assert(limit == bottom,
1865 "the region limit should be at bottom");
1866 // we return NULL and the caller should try calling
1867 // claim_region() again.
1868 return NULL;
1869 }
1870 } else {
1871 assert(_finger > finger, "the finger should have moved forward");
1872 // read it again
1873 finger = _finger;
1874 }
1875 }
1876
1877 return NULL;
1878 }
1879
1880 #ifndef PRODUCT
1881 class VerifyNoCSetOops {
1882 G1CollectedHeap* _g1h;
1883 const char* _phase;
1884 int _info;
1885
1886 public:
1887 VerifyNoCSetOops(const char* phase, int info = -1) :
1888 _g1h(G1CollectedHeap::heap()),
1889 _phase(phase),
1890 _info(info)
1891 { }
1892
1893 void operator()(G1TaskQueueEntry task_entry) const {
1894 if (task_entry.is_array_slice()) {
1895 guarantee(_g1h->is_in_reserved(task_entry.slice()), "Slice " PTR_FORMAT " must be in heap.", p2i(task_entry.slice()));
1896 return;
1897 }
1898 guarantee(oopDesc::is_oop(task_entry.obj()),
1899 "Non-oop " PTR_FORMAT ", phase: %s, info: %d",
1900 p2i(task_entry.obj()), _phase, _info);
1901 HeapRegion* r = _g1h->heap_region_containing(task_entry.obj());
1902 guarantee(!(r->in_collection_set() || r->has_index_in_opt_cset()),
1903 "obj " PTR_FORMAT " from %s (%d) in region %u in (optional) collection set",
1904 p2i(task_entry.obj()), _phase, _info, r->hrm_index());
1905 }
1906 };
1907
1908 void G1ConcurrentMark::verify_no_collection_set_oops() {
1909 assert(SafepointSynchronize::is_at_safepoint(), "should be at a safepoint");
1910 if (!_g1h->collector_state()->mark_or_rebuild_in_progress()) {
1911 return;
1912 }
1913
1914 // Verify entries on the global mark stack
1915 _global_mark_stack.iterate(VerifyNoCSetOops("Stack"));
1916
1917 // Verify entries on the task queues
1918 for (uint i = 0; i < _max_num_tasks; ++i) {
1919 G1CMTaskQueue* queue = _task_queues->queue(i);
1920 queue->iterate(VerifyNoCSetOops("Queue", i));
1921 }
1922
1923 // Verify the global finger
1924 HeapWord* global_finger = finger();
1925 if (global_finger != NULL && global_finger < _heap.end()) {
1926 // Since we always iterate over all regions, we might get a NULL HeapRegion
1927 // here.
1928 HeapRegion* global_hr = _g1h->heap_region_containing(global_finger);
1929 guarantee(global_hr == NULL || global_finger == global_hr->bottom(),
1930 "global finger: " PTR_FORMAT " region: " HR_FORMAT,
1931 p2i(global_finger), HR_FORMAT_PARAMS(global_hr));
1932 }
1933
1934 // Verify the task fingers
1935 assert(_num_concurrent_workers <= _max_num_tasks, "sanity");
1936 for (uint i = 0; i < _num_concurrent_workers; ++i) {
1937 G1CMTask* task = _tasks[i];
1938 HeapWord* task_finger = task->finger();
1939 if (task_finger != NULL && task_finger < _heap.end()) {
1940 // See above note on the global finger verification.
1941 HeapRegion* r = _g1h->heap_region_containing(task_finger);
1942 guarantee(r == NULL || task_finger == r->bottom() ||
1943 !r->in_collection_set() || !r->has_index_in_opt_cset(),
1944 "task finger: " PTR_FORMAT " region: " HR_FORMAT,
1945 p2i(task_finger), HR_FORMAT_PARAMS(r));
1946 }
1947 }
1948 }
1949 #endif // PRODUCT
1950
1951 void G1ConcurrentMark::rebuild_rem_set_concurrently() {
1952 _g1h->rem_set()->rebuild_rem_set(this, _concurrent_workers, _worker_id_offset);
1953 }
1954
1955 void G1ConcurrentMark::print_stats() {
1956 if (!log_is_enabled(Debug, gc, stats)) {
1957 return;
1958 }
1959 log_debug(gc, stats)("---------------------------------------------------------------------");
1960 for (size_t i = 0; i < _num_active_tasks; ++i) {
1961 _tasks[i]->print_stats();
1962 log_debug(gc, stats)("---------------------------------------------------------------------");
1963 }
1964 }
1965
1966 void G1ConcurrentMark::concurrent_cycle_abort_by_initial_mark() {
1967 _aborted_by_initial_mark = true;
1968 _g1h->collector_state()->set_in_initial_mark_gc(false);
1969 }
1970
1971 void G1ConcurrentMark::concurrent_cycle_abort_by_fullgc() {
1972 if (!cm_thread()->during_cycle() || _aborted_by_fullgc) {
1973 // We haven't started a concurrent cycle or we have already aborted it. No need to do anything.
1974 return;
1975 }
1976
1977 // Clear all marks in the next bitmap for the next marking cycle. This will allow us to skip the next
1978 // concurrent bitmap clearing.
1979 {
1980 GCTraceTime(Debug, gc) debug("Clear Next Bitmap");
1981 clear_bitmap(_next_mark_bitmap, _g1h->workers(), false);
1982 }
1983 // Note we cannot clear the previous marking bitmap here
1984 // since VerifyDuringGC verifies the objects marked during
1985 // a full GC against the previous bitmap.
1986
1987 // Empty mark stack
1988 reset_marking_for_restart();
1989 for (uint i = 0; i < _max_num_tasks; ++i) {
1990 _tasks[i]->clear_region_fields();
1991 }
1992 _first_overflow_barrier_sync.abort();
1993 _second_overflow_barrier_sync.abort();
1994 _aborted_by_fullgc = true;
1995
1996 SATBMarkQueueSet& satb_mq_set = G1BarrierSet::satb_mark_queue_set();
1997 satb_mq_set.abandon_partial_marking();
1998 // This can be called either during or outside marking, we'll read
1999 // the expected_active value from the SATB queue set.
2000 satb_mq_set.set_active_all_threads(
2001 false, /* new active value */
2002 satb_mq_set.is_active() /* expected_active */);
2003 }
2004
2005 static void print_ms_time_info(const char* prefix, const char* name,
2006 NumberSeq& ns) {
2007 log_trace(gc, marking)("%s%5d %12s: total time = %8.2f s (avg = %8.2f ms).",
2008 prefix, ns.num(), name, ns.sum()/1000.0, ns.avg());
2009 if (ns.num() > 0) {
2010 log_trace(gc, marking)("%s [std. dev = %8.2f ms, max = %8.2f ms]",
2011 prefix, ns.sd(), ns.maximum());
2012 }
2013 }
2014
2015 void G1ConcurrentMark::print_summary_info() {
2016 Log(gc, marking) log;
2017 if (!log.is_trace()) {
2018 return;
2019 }
2020
2021 log.trace(" Concurrent marking:");
2022 print_ms_time_info(" ", "init marks", _init_times);
2023 print_ms_time_info(" ", "remarks", _remark_times);
2024 {
2025 print_ms_time_info(" ", "final marks", _remark_mark_times);
2026 print_ms_time_info(" ", "weak refs", _remark_weak_ref_times);
2027
2028 }
2029 print_ms_time_info(" ", "cleanups", _cleanup_times);
2030 log.trace(" Finalize live data total time = %8.2f s (avg = %8.2f ms).",
2031 _total_cleanup_time, (_cleanup_times.num() > 0 ? _total_cleanup_time * 1000.0 / (double)_cleanup_times.num() : 0.0));
2032 log.trace(" Total stop_world time = %8.2f s.",
2033 (_init_times.sum() + _remark_times.sum() + _cleanup_times.sum())/1000.0);
2034 log.trace(" Total concurrent time = %8.2f s (%8.2f s marking).",
2035 cm_thread()->vtime_accum(), cm_thread()->vtime_mark_accum());
2036 }
2037
2038 void G1ConcurrentMark::print_worker_threads_on(outputStream* st) const {
2039 _concurrent_workers->print_worker_threads_on(st);
2040 }
2041
2042 void G1ConcurrentMark::threads_do(ThreadClosure* tc) const {
2043 _concurrent_workers->threads_do(tc);
2044 }
2045
2046 void G1ConcurrentMark::print_on_error(outputStream* st) const {
2047 st->print_cr("Marking Bits (Prev, Next): (CMBitMap*) " PTR_FORMAT ", (CMBitMap*) " PTR_FORMAT,
2048 p2i(_prev_mark_bitmap), p2i(_next_mark_bitmap));
2049 _prev_mark_bitmap->print_on_error(st, " Prev Bits: ");
2050 _next_mark_bitmap->print_on_error(st, " Next Bits: ");
2051 }
2052
2053 static ReferenceProcessor* get_cm_oop_closure_ref_processor(G1CollectedHeap* g1h) {
2054 ReferenceProcessor* result = g1h->ref_processor_cm();
2055 assert(result != NULL, "CM reference processor should not be NULL");
2056 return result;
2057 }
2058
2059 G1CMOopClosure::G1CMOopClosure(G1CollectedHeap* g1h,
2060 G1CMTask* task)
2061 : MetadataVisitingOopIterateClosure(get_cm_oop_closure_ref_processor(g1h)),
2062 _g1h(g1h), _task(task)
2063 { }
2064
2065 void G1CMTask::setup_for_region(HeapRegion* hr) {
2066 assert(hr != NULL,
2067 "claim_region() should have filtered out NULL regions");
2068 _curr_region = hr;
2069 _finger = hr->bottom();
2070 update_region_limit();
2071 }
2072
2073 void G1CMTask::update_region_limit() {
2074 HeapRegion* hr = _curr_region;
2075 HeapWord* bottom = hr->bottom();
2076 HeapWord* limit = hr->next_top_at_mark_start();
2077
2078 if (limit == bottom) {
2079 // The region was collected underneath our feet.
2080 // We set the finger to bottom to ensure that the bitmap
2081 // iteration that will follow this will not do anything.
2082 // (this is not a condition that holds when we set the region up,
2083 // as the region is not supposed to be empty in the first place)
2084 _finger = bottom;
2085 } else if (limit >= _region_limit) {
2086 assert(limit >= _finger, "peace of mind");
2087 } else {
2088 assert(limit < _region_limit, "only way to get here");
2089 // This can happen under some pretty unusual circumstances. An
2090 // evacuation pause empties the region underneath our feet (NTAMS
2091 // at bottom). We then do some allocation in the region (NTAMS
2092 // stays at bottom), followed by the region being used as a GC
2093 // alloc region (NTAMS will move to top() and the objects
2094 // originally below it will be grayed). All objects now marked in
2095 // the region are explicitly grayed, if below the global finger,
2096 // and we do not need in fact to scan anything else. So, we simply
2097 // set _finger to be limit to ensure that the bitmap iteration
2098 // doesn't do anything.
2099 _finger = limit;
2100 }
2101
2102 _region_limit = limit;
2103 }
2104
2105 void G1CMTask::giveup_current_region() {
2106 assert(_curr_region != NULL, "invariant");
2107 clear_region_fields();
2108 }
2109
2110 void G1CMTask::clear_region_fields() {
2111 // Values for these three fields that indicate that we're not
2112 // holding on to a region.
2113 _curr_region = NULL;
2114 _finger = NULL;
2115 _region_limit = NULL;
2116 }
2117
2118 void G1CMTask::set_cm_oop_closure(G1CMOopClosure* cm_oop_closure) {
2119 if (cm_oop_closure == NULL) {
2120 assert(_cm_oop_closure != NULL, "invariant");
2121 } else {
2122 assert(_cm_oop_closure == NULL, "invariant");
2123 }
2124 _cm_oop_closure = cm_oop_closure;
2125 }
2126
2127 void G1CMTask::reset(G1CMBitMap* next_mark_bitmap) {
2128 guarantee(next_mark_bitmap != NULL, "invariant");
2129 _next_mark_bitmap = next_mark_bitmap;
2130 clear_region_fields();
2131
2132 _calls = 0;
2133 _elapsed_time_ms = 0.0;
2134 _termination_time_ms = 0.0;
2135 _termination_start_time_ms = 0.0;
2136
2137 _mark_stats_cache.reset();
2138 }
2139
2140 bool G1CMTask::should_exit_termination() {
2141 if (!regular_clock_call()) {
2142 return true;
2143 }
2144
2145 // This is called when we are in the termination protocol. We should
2146 // quit if, for some reason, this task wants to abort or the global
2147 // stack is not empty (this means that we can get work from it).
2148 return !_cm->mark_stack_empty() || has_aborted();
2149 }
2150
2151 void G1CMTask::reached_limit() {
2152 assert(_words_scanned >= _words_scanned_limit ||
2153 _refs_reached >= _refs_reached_limit ,
2154 "shouldn't have been called otherwise");
2155 abort_marking_if_regular_check_fail();
2156 }
2157
2158 bool G1CMTask::regular_clock_call() {
2159 if (has_aborted()) {
2160 return false;
2161 }
2162
2163 // First, we need to recalculate the words scanned and refs reached
2164 // limits for the next clock call.
2165 recalculate_limits();
2166
2167 // During the regular clock call we do the following
2168
2169 // (1) If an overflow has been flagged, then we abort.
2170 if (_cm->has_overflown()) {
2171 return false;
2172 }
2173
2174 // If we are not concurrent (i.e. we're doing remark) we don't need
2175 // to check anything else. The other steps are only needed during
2176 // the concurrent marking phase.
2177 if (!_cm->concurrent()) {
2178 return true;
2179 }
2180
2181 // (2) If marking has been aborted for Full GC, then we also abort.
2182 if (_cm->has_aborted()) {
2183 return false;
2184 }
2185
2186 double curr_time_ms = os::elapsedVTime() * 1000.0;
2187
2188 // (4) We check whether we should yield. If we have to, then we abort.
2189 if (SuspendibleThreadSet::should_yield()) {
2190 // We should yield. To do this we abort the task. The caller is
2191 // responsible for yielding.
2192 return false;
2193 }
2194
2195 // (5) We check whether we've reached our time quota. If we have,
2196 // then we abort.
2197 double elapsed_time_ms = curr_time_ms - _start_time_ms;
2198 if (elapsed_time_ms > _time_target_ms) {
2199 _has_timed_out = true;
2200 return false;
2201 }
2202
2203 // (6) Finally, we check whether there are enough completed STAB
2204 // buffers available for processing. If there are, we abort.
2205 SATBMarkQueueSet& satb_mq_set = G1BarrierSet::satb_mark_queue_set();
2206 if (!_draining_satb_buffers && satb_mq_set.process_completed_buffers()) {
2207 // we do need to process SATB buffers, we'll abort and restart
2208 // the marking task to do so
2209 return false;
2210 }
2211 return true;
2212 }
2213
2214 void G1CMTask::recalculate_limits() {
2215 _real_words_scanned_limit = _words_scanned + words_scanned_period;
2216 _words_scanned_limit = _real_words_scanned_limit;
2217
2218 _real_refs_reached_limit = _refs_reached + refs_reached_period;
2219 _refs_reached_limit = _real_refs_reached_limit;
2220 }
2221
2222 void G1CMTask::decrease_limits() {
2223 // This is called when we believe that we're going to do an infrequent
2224 // operation which will increase the per byte scanned cost (i.e. move
2225 // entries to/from the global stack). It basically tries to decrease the
2226 // scanning limit so that the clock is called earlier.
2227
2228 _words_scanned_limit = _real_words_scanned_limit - 3 * words_scanned_period / 4;
2229 _refs_reached_limit = _real_refs_reached_limit - 3 * refs_reached_period / 4;
2230 }
2231
2232 void G1CMTask::move_entries_to_global_stack() {
2233 // Local array where we'll store the entries that will be popped
2234 // from the local queue.
2235 G1TaskQueueEntry buffer[G1CMMarkStack::EntriesPerChunk];
2236
2237 size_t n = 0;
2238 G1TaskQueueEntry task_entry;
2239 while (n < G1CMMarkStack::EntriesPerChunk && _task_queue->pop_local(task_entry)) {
2240 buffer[n] = task_entry;
2241 ++n;
2242 }
2243 if (n < G1CMMarkStack::EntriesPerChunk) {
2244 buffer[n] = G1TaskQueueEntry();
2245 }
2246
2247 if (n > 0) {
2248 if (!_cm->mark_stack_push(buffer)) {
2249 set_has_aborted();
2250 }
2251 }
2252
2253 // This operation was quite expensive, so decrease the limits.
2254 decrease_limits();
2255 }
2256
2257 bool G1CMTask::get_entries_from_global_stack() {
2258 // Local array where we'll store the entries that will be popped
2259 // from the global stack.
2260 G1TaskQueueEntry buffer[G1CMMarkStack::EntriesPerChunk];
2261
2262 if (!_cm->mark_stack_pop(buffer)) {
2263 return false;
2264 }
2265
2266 // We did actually pop at least one entry.
2267 for (size_t i = 0; i < G1CMMarkStack::EntriesPerChunk; ++i) {
2268 G1TaskQueueEntry task_entry = buffer[i];
2269 if (task_entry.is_null()) {
2270 break;
2271 }
2272 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()));
2273 bool success = _task_queue->push(task_entry);
2274 // We only call this when the local queue is empty or under a
2275 // given target limit. So, we do not expect this push to fail.
2276 assert(success, "invariant");
2277 }
2278
2279 // This operation was quite expensive, so decrease the limits
2280 decrease_limits();
2281 return true;
2282 }
2283
2284 void G1CMTask::drain_local_queue(bool partially) {
2285 if (has_aborted()) {
2286 return;
2287 }
2288
2289 // Decide what the target size is, depending whether we're going to
2290 // drain it partially (so that other tasks can steal if they run out
2291 // of things to do) or totally (at the very end).
2292 size_t target_size;
2293 if (partially) {
2294 target_size = MIN2((size_t)_task_queue->max_elems()/3, (size_t)GCDrainStackTargetSize);
2295 } else {
2296 target_size = 0;
2297 }
2298
2299 if (_task_queue->size() > target_size) {
2300 G1TaskQueueEntry entry;
2301 bool ret = _task_queue->pop_local(entry);
2302 while (ret) {
2303 scan_task_entry(entry);
2304 if (_task_queue->size() <= target_size || has_aborted()) {
2305 ret = false;
2306 } else {
2307 ret = _task_queue->pop_local(entry);
2308 }
2309 }
2310 }
2311 }
2312
2313 void G1CMTask::drain_global_stack(bool partially) {
2314 if (has_aborted()) {
2315 return;
2316 }
2317
2318 // We have a policy to drain the local queue before we attempt to
2319 // drain the global stack.
2320 assert(partially || _task_queue->size() == 0, "invariant");
2321
2322 // Decide what the target size is, depending whether we're going to
2323 // drain it partially (so that other tasks can steal if they run out
2324 // of things to do) or totally (at the very end).
2325 // Notice that when draining the global mark stack partially, due to the racyness
2326 // of the mark stack size update we might in fact drop below the target. But,
2327 // this is not a problem.
2328 // In case of total draining, we simply process until the global mark stack is
2329 // totally empty, disregarding the size counter.
2330 if (partially) {
2331 size_t const target_size = _cm->partial_mark_stack_size_target();
2332 while (!has_aborted() && _cm->mark_stack_size() > target_size) {
2333 if (get_entries_from_global_stack()) {
2334 drain_local_queue(partially);
2335 }
2336 }
2337 } else {
2338 while (!has_aborted() && get_entries_from_global_stack()) {
2339 drain_local_queue(partially);
2340 }
2341 }
2342 }
2343
2344 // SATB Queue has several assumptions on whether to call the par or
2345 // non-par versions of the methods. this is why some of the code is
2346 // replicated. We should really get rid of the single-threaded version
2347 // of the code to simplify things.
2348 void G1CMTask::drain_satb_buffers() {
2349 if (has_aborted()) {
2350 return;
2351 }
2352
2353 // We set this so that the regular clock knows that we're in the
2354 // middle of draining buffers and doesn't set the abort flag when it
2355 // notices that SATB buffers are available for draining. It'd be
2356 // very counter productive if it did that. :-)
2357 _draining_satb_buffers = true;
2358
2359 G1CMSATBBufferClosure satb_cl(this, _g1h);
2360 SATBMarkQueueSet& satb_mq_set = G1BarrierSet::satb_mark_queue_set();
2361
2362 // This keeps claiming and applying the closure to completed buffers
2363 // until we run out of buffers or we need to abort.
2364 while (!has_aborted() &&
2365 satb_mq_set.apply_closure_to_completed_buffer(&satb_cl)) {
2366 abort_marking_if_regular_check_fail();
2367 }
2368
2369 // Can't assert qset is empty here, even if not aborted. If concurrent,
2370 // some other thread might be adding to the queue. If not concurrent,
2371 // some other thread might have won the race for the last buffer, but
2372 // has not yet decremented the count.
2373
2374 _draining_satb_buffers = false;
2375
2376 // again, this was a potentially expensive operation, decrease the
2377 // limits to get the regular clock call early
2378 decrease_limits();
2379 }
2380
2381 void G1CMTask::clear_mark_stats_cache(uint region_idx) {
2382 _mark_stats_cache.reset(region_idx);
2383 }
2384
2385 Pair<size_t, size_t> G1CMTask::flush_mark_stats_cache() {
2386 return _mark_stats_cache.evict_all();
2387 }
2388
2389 void G1CMTask::print_stats() {
2390 log_debug(gc, stats)("Marking Stats, task = %u, calls = %u", _worker_id, _calls);
2391 log_debug(gc, stats)(" Elapsed time = %1.2lfms, Termination time = %1.2lfms",
2392 _elapsed_time_ms, _termination_time_ms);
2393 log_debug(gc, stats)(" Step Times (cum): num = %d, avg = %1.2lfms, sd = %1.2lfms max = %1.2lfms, total = %1.2lfms",
2394 _step_times_ms.num(),
2395 _step_times_ms.avg(),
2396 _step_times_ms.sd(),
2397 _step_times_ms.maximum(),
2398 _step_times_ms.sum());
2399 size_t const hits = _mark_stats_cache.hits();
2400 size_t const misses = _mark_stats_cache.misses();
2401 log_debug(gc, stats)(" Mark Stats Cache: hits " SIZE_FORMAT " misses " SIZE_FORMAT " ratio %.3f",
2402 hits, misses, percent_of(hits, hits + misses));
2403 }
2404
2405 bool G1ConcurrentMark::try_stealing(uint worker_id, G1TaskQueueEntry& task_entry) {
2406 return _task_queues->steal(worker_id, task_entry);
2407 }
2408
2409 /*****************************************************************************
2410
2411 The do_marking_step(time_target_ms, ...) method is the building
2412 block of the parallel marking framework. It can be called in parallel
2413 with other invocations of do_marking_step() on different tasks
2414 (but only one per task, obviously) and concurrently with the
2415 mutator threads, or during remark, hence it eliminates the need
2416 for two versions of the code. When called during remark, it will
2417 pick up from where the task left off during the concurrent marking
2418 phase. Interestingly, tasks are also claimable during evacuation
2419 pauses too, since do_marking_step() ensures that it aborts before
2420 it needs to yield.
2421
2422 The data structures that it uses to do marking work are the
2423 following:
2424
2425 (1) Marking Bitmap. If there are gray objects that appear only
2426 on the bitmap (this happens either when dealing with an overflow
2427 or when the initial marking phase has simply marked the roots
2428 and didn't push them on the stack), then tasks claim heap
2429 regions whose bitmap they then scan to find gray objects. A
2430 global finger indicates where the end of the last claimed region
2431 is. A local finger indicates how far into the region a task has
2432 scanned. The two fingers are used to determine how to gray an
2433 object (i.e. whether simply marking it is OK, as it will be
2434 visited by a task in the future, or whether it needs to be also
2435 pushed on a stack).
2436
2437 (2) Local Queue. The local queue of the task which is accessed
2438 reasonably efficiently by the task. Other tasks can steal from
2439 it when they run out of work. Throughout the marking phase, a
2440 task attempts to keep its local queue short but not totally
2441 empty, so that entries are available for stealing by other
2442 tasks. Only when there is no more work, a task will totally
2443 drain its local queue.
2444
2445 (3) Global Mark Stack. This handles local queue overflow. During
2446 marking only sets of entries are moved between it and the local
2447 queues, as access to it requires a mutex and more fine-grain
2448 interaction with it which might cause contention. If it
2449 overflows, then the marking phase should restart and iterate
2450 over the bitmap to identify gray objects. Throughout the marking
2451 phase, tasks attempt to keep the global mark stack at a small
2452 length but not totally empty, so that entries are available for
2453 popping by other tasks. Only when there is no more work, tasks
2454 will totally drain the global mark stack.
2455
2456 (4) SATB Buffer Queue. This is where completed SATB buffers are
2457 made available. Buffers are regularly removed from this queue
2458 and scanned for roots, so that the queue doesn't get too
2459 long. During remark, all completed buffers are processed, as
2460 well as the filled in parts of any uncompleted buffers.
2461
2462 The do_marking_step() method tries to abort when the time target
2463 has been reached. There are a few other cases when the
2464 do_marking_step() method also aborts:
2465
2466 (1) When the marking phase has been aborted (after a Full GC).
2467
2468 (2) When a global overflow (on the global stack) has been
2469 triggered. Before the task aborts, it will actually sync up with
2470 the other tasks to ensure that all the marking data structures
2471 (local queues, stacks, fingers etc.) are re-initialized so that
2472 when do_marking_step() completes, the marking phase can
2473 immediately restart.
2474
2475 (3) When enough completed SATB buffers are available. The
2476 do_marking_step() method only tries to drain SATB buffers right
2477 at the beginning. So, if enough buffers are available, the
2478 marking step aborts and the SATB buffers are processed at
2479 the beginning of the next invocation.
2480
2481 (4) To yield. when we have to yield then we abort and yield
2482 right at the end of do_marking_step(). This saves us from a lot
2483 of hassle as, by yielding we might allow a Full GC. If this
2484 happens then objects will be compacted underneath our feet, the
2485 heap might shrink, etc. We save checking for this by just
2486 aborting and doing the yield right at the end.
2487
2488 From the above it follows that the do_marking_step() method should
2489 be called in a loop (or, otherwise, regularly) until it completes.
2490
2491 If a marking step completes without its has_aborted() flag being
2492 true, it means it has completed the current marking phase (and
2493 also all other marking tasks have done so and have all synced up).
2494
2495 A method called regular_clock_call() is invoked "regularly" (in
2496 sub ms intervals) throughout marking. It is this clock method that
2497 checks all the abort conditions which were mentioned above and
2498 decides when the task should abort. A work-based scheme is used to
2499 trigger this clock method: when the number of object words the
2500 marking phase has scanned or the number of references the marking
2501 phase has visited reach a given limit. Additional invocations to
2502 the method clock have been planted in a few other strategic places
2503 too. The initial reason for the clock method was to avoid calling
2504 vtime too regularly, as it is quite expensive. So, once it was in
2505 place, it was natural to piggy-back all the other conditions on it
2506 too and not constantly check them throughout the code.
2507
2508 If do_termination is true then do_marking_step will enter its
2509 termination protocol.
2510
2511 The value of is_serial must be true when do_marking_step is being
2512 called serially (i.e. by the VMThread) and do_marking_step should
2513 skip any synchronization in the termination and overflow code.
2514 Examples include the serial remark code and the serial reference
2515 processing closures.
2516
2517 The value of is_serial must be false when do_marking_step is
2518 being called by any of the worker threads in a work gang.
2519 Examples include the concurrent marking code (CMMarkingTask),
2520 the MT remark code, and the MT reference processing closures.
2521
2522 *****************************************************************************/
2523
2524 void G1CMTask::do_marking_step(double time_target_ms,
2525 bool do_termination,
2526 bool is_serial) {
2527 assert(time_target_ms >= 1.0, "minimum granularity is 1ms");
2528
2529 _start_time_ms = os::elapsedVTime() * 1000.0;
2530
2531 // If do_stealing is true then do_marking_step will attempt to
2532 // steal work from the other G1CMTasks. It only makes sense to
2533 // enable stealing when the termination protocol is enabled
2534 // and do_marking_step() is not being called serially.
2535 bool do_stealing = do_termination && !is_serial;
2536
2537 G1Predictions const& predictor = _g1h->policy()->predictor();
2538 double diff_prediction_ms = predictor.predict_zero_bounded(&_marking_step_diff_ms);
2539 _time_target_ms = time_target_ms - diff_prediction_ms;
2540
2541 // set up the variables that are used in the work-based scheme to
2542 // call the regular clock method
2543 _words_scanned = 0;
2544 _refs_reached = 0;
2545 recalculate_limits();
2546
2547 // clear all flags
2548 clear_has_aborted();
2549 _has_timed_out = false;
2550 _draining_satb_buffers = false;
2551
2552 ++_calls;
2553
2554 // Set up the bitmap and oop closures. Anything that uses them is
2555 // eventually called from this method, so it is OK to allocate these
2556 // statically.
2557 G1CMBitMapClosure bitmap_closure(this, _cm);
2558 G1CMOopClosure cm_oop_closure(_g1h, this);
2559 set_cm_oop_closure(&cm_oop_closure);
2560
2561 if (_cm->has_overflown()) {
2562 // This can happen if the mark stack overflows during a GC pause
2563 // and this task, after a yield point, restarts. We have to abort
2564 // as we need to get into the overflow protocol which happens
2565 // right at the end of this task.
2566 set_has_aborted();
2567 }
2568
2569 // First drain any available SATB buffers. After this, we will not
2570 // look at SATB buffers before the next invocation of this method.
2571 // If enough completed SATB buffers are queued up, the regular clock
2572 // will abort this task so that it restarts.
2573 drain_satb_buffers();
2574 // ...then partially drain the local queue and the global stack
2575 drain_local_queue(true);
2576 drain_global_stack(true);
2577
2578 do {
2579 if (!has_aborted() && _curr_region != NULL) {
2580 // This means that we're already holding on to a region.
2581 assert(_finger != NULL, "if region is not NULL, then the finger "
2582 "should not be NULL either");
2583
2584 // We might have restarted this task after an evacuation pause
2585 // which might have evacuated the region we're holding on to
2586 // underneath our feet. Let's read its limit again to make sure
2587 // that we do not iterate over a region of the heap that
2588 // contains garbage (update_region_limit() will also move
2589 // _finger to the start of the region if it is found empty).
2590 update_region_limit();
2591 // We will start from _finger not from the start of the region,
2592 // as we might be restarting this task after aborting half-way
2593 // through scanning this region. In this case, _finger points to
2594 // the address where we last found a marked object. If this is a
2595 // fresh region, _finger points to start().
2596 MemRegion mr = MemRegion(_finger, _region_limit);
2597
2598 assert(!_curr_region->is_humongous() || mr.start() == _curr_region->bottom(),
2599 "humongous regions should go around loop once only");
2600
2601 // Some special cases:
2602 // If the memory region is empty, we can just give up the region.
2603 // If the current region is humongous then we only need to check
2604 // the bitmap for the bit associated with the start of the object,
2605 // scan the object if it's live, and give up the region.
2606 // Otherwise, let's iterate over the bitmap of the part of the region
2607 // that is left.
2608 // If the iteration is successful, give up the region.
2609 if (mr.is_empty()) {
2610 giveup_current_region();
2611 abort_marking_if_regular_check_fail();
2612 } else if (_curr_region->is_humongous() && mr.start() == _curr_region->bottom()) {
2613 if (_next_mark_bitmap->is_marked(mr.start())) {
2614 // The object is marked - apply the closure
2615 bitmap_closure.do_addr(mr.start());
2616 }
2617 // Even if this task aborted while scanning the humongous object
2618 // we can (and should) give up the current region.
2619 giveup_current_region();
2620 abort_marking_if_regular_check_fail();
2621 } else if (_next_mark_bitmap->iterate(&bitmap_closure, mr)) {
2622 giveup_current_region();
2623 abort_marking_if_regular_check_fail();
2624 } else {
2625 assert(has_aborted(), "currently the only way to do so");
2626 // The only way to abort the bitmap iteration is to return
2627 // false from the do_bit() method. However, inside the
2628 // do_bit() method we move the _finger to point to the
2629 // object currently being looked at. So, if we bail out, we
2630 // have definitely set _finger to something non-null.
2631 assert(_finger != NULL, "invariant");
2632
2633 // Region iteration was actually aborted. So now _finger
2634 // points to the address of the object we last scanned. If we
2635 // leave it there, when we restart this task, we will rescan
2636 // the object. It is easy to avoid this. We move the finger by
2637 // enough to point to the next possible object header.
2638 assert(_finger < _region_limit, "invariant");
2639 HeapWord* const new_finger = _finger + ((oop)_finger)->size();
2640 // Check if bitmap iteration was aborted while scanning the last object
2641 if (new_finger >= _region_limit) {
2642 giveup_current_region();
2643 } else {
2644 move_finger_to(new_finger);
2645 }
2646 }
2647 }
2648 // At this point we have either completed iterating over the
2649 // region we were holding on to, or we have aborted.
2650
2651 // We then partially drain the local queue and the global stack.
2652 // (Do we really need this?)
2653 drain_local_queue(true);
2654 drain_global_stack(true);
2655
2656 // Read the note on the claim_region() method on why it might
2657 // return NULL with potentially more regions available for
2658 // claiming and why we have to check out_of_regions() to determine
2659 // whether we're done or not.
2660 while (!has_aborted() && _curr_region == NULL && !_cm->out_of_regions()) {
2661 // We are going to try to claim a new region. We should have
2662 // given up on the previous one.
2663 // Separated the asserts so that we know which one fires.
2664 assert(_curr_region == NULL, "invariant");
2665 assert(_finger == NULL, "invariant");
2666 assert(_region_limit == NULL, "invariant");
2667 HeapRegion* claimed_region = _cm->claim_region(_worker_id);
2668 if (claimed_region != NULL) {
2669 // Yes, we managed to claim one
2670 setup_for_region(claimed_region);
2671 assert(_curr_region == claimed_region, "invariant");
2672 }
2673 // It is important to call the regular clock here. It might take
2674 // a while to claim a region if, for example, we hit a large
2675 // block of empty regions. So we need to call the regular clock
2676 // method once round the loop to make sure it's called
2677 // frequently enough.
2678 abort_marking_if_regular_check_fail();
2679 }
2680
2681 if (!has_aborted() && _curr_region == NULL) {
2682 assert(_cm->out_of_regions(),
2683 "at this point we should be out of regions");
2684 }
2685 } while ( _curr_region != NULL && !has_aborted());
2686
2687 if (!has_aborted()) {
2688 // We cannot check whether the global stack is empty, since other
2689 // tasks might be pushing objects to it concurrently.
2690 assert(_cm->out_of_regions(),
2691 "at this point we should be out of regions");
2692 // Try to reduce the number of available SATB buffers so that
2693 // remark has less work to do.
2694 drain_satb_buffers();
2695 }
2696
2697 // Since we've done everything else, we can now totally drain the
2698 // local queue and global stack.
2699 drain_local_queue(false);
2700 drain_global_stack(false);
2701
2702 // Attempt at work stealing from other task's queues.
2703 if (do_stealing && !has_aborted()) {
2704 // We have not aborted. This means that we have finished all that
2705 // we could. Let's try to do some stealing...
2706
2707 // We cannot check whether the global stack is empty, since other
2708 // tasks might be pushing objects to it concurrently.
2709 assert(_cm->out_of_regions() && _task_queue->size() == 0,
2710 "only way to reach here");
2711 while (!has_aborted()) {
2712 G1TaskQueueEntry entry;
2713 if (_cm->try_stealing(_worker_id, entry)) {
2714 scan_task_entry(entry);
2715
2716 // And since we're towards the end, let's totally drain the
2717 // local queue and global stack.
2718 drain_local_queue(false);
2719 drain_global_stack(false);
2720 } else {
2721 break;
2722 }
2723 }
2724 }
2725
2726 // We still haven't aborted. Now, let's try to get into the
2727 // termination protocol.
2728 if (do_termination && !has_aborted()) {
2729 // We cannot check whether the global stack is empty, since other
2730 // tasks might be concurrently pushing objects on it.
2731 // Separated the asserts so that we know which one fires.
2732 assert(_cm->out_of_regions(), "only way to reach here");
2733 assert(_task_queue->size() == 0, "only way to reach here");
2734 _termination_start_time_ms = os::elapsedVTime() * 1000.0;
2735
2736 // The G1CMTask class also extends the TerminatorTerminator class,
2737 // hence its should_exit_termination() method will also decide
2738 // whether to exit the termination protocol or not.
2739 bool finished = (is_serial ||
2740 _cm->terminator()->offer_termination(this));
2741 double termination_end_time_ms = os::elapsedVTime() * 1000.0;
2742 _termination_time_ms +=
2743 termination_end_time_ms - _termination_start_time_ms;
2744
2745 if (finished) {
2746 // We're all done.
2747
2748 // We can now guarantee that the global stack is empty, since
2749 // all other tasks have finished. We separated the guarantees so
2750 // that, if a condition is false, we can immediately find out
2751 // which one.
2752 guarantee(_cm->out_of_regions(), "only way to reach here");
2753 guarantee(_cm->mark_stack_empty(), "only way to reach here");
2754 guarantee(_task_queue->size() == 0, "only way to reach here");
2755 guarantee(!_cm->has_overflown(), "only way to reach here");
2756 guarantee(!has_aborted(), "should never happen if termination has completed");
2757 } else {
2758 // Apparently there's more work to do. Let's abort this task. It
2759 // will restart it and we can hopefully find more things to do.
2760 set_has_aborted();
2761 }
2762 }
2763
2764 // Mainly for debugging purposes to make sure that a pointer to the
2765 // closure which was statically allocated in this frame doesn't
2766 // escape it by accident.
2767 set_cm_oop_closure(NULL);
2768 double end_time_ms = os::elapsedVTime() * 1000.0;
2769 double elapsed_time_ms = end_time_ms - _start_time_ms;
2770 // Update the step history.
2771 _step_times_ms.add(elapsed_time_ms);
2772
2773 if (has_aborted()) {
2774 // The task was aborted for some reason.
2775 if (_has_timed_out) {
2776 double diff_ms = elapsed_time_ms - _time_target_ms;
2777 // Keep statistics of how well we did with respect to hitting
2778 // our target only if we actually timed out (if we aborted for
2779 // other reasons, then the results might get skewed).
2780 _marking_step_diff_ms.add(diff_ms);
2781 }
2782
2783 if (_cm->has_overflown()) {
2784 // This is the interesting one. We aborted because a global
2785 // overflow was raised. This means we have to restart the
2786 // marking phase and start iterating over regions. However, in
2787 // order to do this we have to make sure that all tasks stop
2788 // what they are doing and re-initialize in a safe manner. We
2789 // will achieve this with the use of two barrier sync points.
2790
2791 if (!is_serial) {
2792 // We only need to enter the sync barrier if being called
2793 // from a parallel context
2794 _cm->enter_first_sync_barrier(_worker_id);
2795
2796 // When we exit this sync barrier we know that all tasks have
2797 // stopped doing marking work. So, it's now safe to
2798 // re-initialize our data structures.
2799 }
2800
2801 clear_region_fields();
2802 flush_mark_stats_cache();
2803
2804 if (!is_serial) {
2805 // If we're executing the concurrent phase of marking, reset the marking
2806 // state; otherwise the marking state is reset after reference processing,
2807 // during the remark pause.
2808 // If we reset here as a result of an overflow during the remark we will
2809 // see assertion failures from any subsequent set_concurrency_and_phase()
2810 // calls.
2811 if (_cm->concurrent() && _worker_id == 0) {
2812 // Worker 0 is responsible for clearing the global data structures because
2813 // of an overflow. During STW we should not clear the overflow flag (in
2814 // G1ConcurrentMark::reset_marking_state()) since we rely on it being true when we exit
2815 // method to abort the pause and restart concurrent marking.
2816 _cm->reset_marking_for_restart();
2817
2818 log_info(gc, marking)("Concurrent Mark reset for overflow");
2819 }
2820
2821 // ...and enter the second barrier.
2822 _cm->enter_second_sync_barrier(_worker_id);
2823 }
2824 // At this point, if we're during the concurrent phase of
2825 // marking, everything has been re-initialized and we're
2826 // ready to restart.
2827 }
2828 }
2829 }
2830
2831 G1CMTask::G1CMTask(uint worker_id,
2832 G1ConcurrentMark* cm,
2833 G1CMTaskQueue* task_queue,
2834 G1RegionMarkStats* mark_stats,
2835 uint max_regions) :
2836 _objArray_processor(this),
2837 _worker_id(worker_id),
2838 _g1h(G1CollectedHeap::heap()),
2839 _cm(cm),
2840 _next_mark_bitmap(NULL),
2841 _task_queue(task_queue),
2842 _mark_stats_cache(mark_stats, max_regions, RegionMarkStatsCacheSize),
2843 _calls(0),
2844 _time_target_ms(0.0),
2845 _start_time_ms(0.0),
2846 _cm_oop_closure(NULL),
2847 _curr_region(NULL),
2848 _finger(NULL),
2849 _region_limit(NULL),
2850 _words_scanned(0),
2851 _words_scanned_limit(0),
2852 _real_words_scanned_limit(0),
2853 _refs_reached(0),
2854 _refs_reached_limit(0),
2855 _real_refs_reached_limit(0),
2856 _has_aborted(false),
2857 _has_timed_out(false),
2858 _draining_satb_buffers(false),
2859 _step_times_ms(),
2860 _elapsed_time_ms(0.0),
2861 _termination_time_ms(0.0),
2862 _termination_start_time_ms(0.0),
2863 _marking_step_diff_ms()
2864 {
2865 guarantee(task_queue != NULL, "invariant");
2866
2867 _marking_step_diff_ms.add(0.5);
2868 }
2869
2870 // These are formatting macros that are used below to ensure
2871 // consistent formatting. The *_H_* versions are used to format the
2872 // header for a particular value and they should be kept consistent
2873 // with the corresponding macro. Also note that most of the macros add
2874 // the necessary white space (as a prefix) which makes them a bit
2875 // easier to compose.
2876
2877 // All the output lines are prefixed with this string to be able to
2878 // identify them easily in a large log file.
2879 #define G1PPRL_LINE_PREFIX "###"
2880
2881 #define G1PPRL_ADDR_BASE_FORMAT " " PTR_FORMAT "-" PTR_FORMAT
2882 #ifdef _LP64
2883 #define G1PPRL_ADDR_BASE_H_FORMAT " %37s"
2884 #else // _LP64
2885 #define G1PPRL_ADDR_BASE_H_FORMAT " %21s"
2886 #endif // _LP64
2887
2888 // For per-region info
2889 #define G1PPRL_TYPE_FORMAT " %-4s"
2890 #define G1PPRL_TYPE_H_FORMAT " %4s"
2891 #define G1PPRL_STATE_FORMAT " %-5s"
2892 #define G1PPRL_STATE_H_FORMAT " %5s"
2893 #define G1PPRL_BYTE_FORMAT " " SIZE_FORMAT_W(9)
2894 #define G1PPRL_BYTE_H_FORMAT " %9s"
2895 #define G1PPRL_DOUBLE_FORMAT " %14.1f"
2896 #define G1PPRL_DOUBLE_H_FORMAT " %14s"
2897
2898 // For summary info
2899 #define G1PPRL_SUM_ADDR_FORMAT(tag) " " tag ":" G1PPRL_ADDR_BASE_FORMAT
2900 #define G1PPRL_SUM_BYTE_FORMAT(tag) " " tag ": " SIZE_FORMAT
2901 #define G1PPRL_SUM_MB_FORMAT(tag) " " tag ": %1.2f MB"
2902 #define G1PPRL_SUM_MB_PERC_FORMAT(tag) G1PPRL_SUM_MB_FORMAT(tag) " / %1.2f %%"
2903
2904 G1PrintRegionLivenessInfoClosure::G1PrintRegionLivenessInfoClosure(const char* phase_name) :
2905 _total_used_bytes(0), _total_capacity_bytes(0),
2906 _total_prev_live_bytes(0), _total_next_live_bytes(0),
2907 _total_remset_bytes(0), _total_strong_code_roots_bytes(0)
2908 {
2909 if (!log_is_enabled(Trace, gc, liveness)) {
2910 return;
2911 }
2912
2913 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2914 MemRegion g1_reserved = g1h->g1_reserved();
2915 double now = os::elapsedTime();
2916
2917 // Print the header of the output.
2918 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX" PHASE %s @ %1.3f", phase_name, now);
2919 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX" HEAP"
2920 G1PPRL_SUM_ADDR_FORMAT("reserved")
2921 G1PPRL_SUM_BYTE_FORMAT("region-size"),
2922 p2i(g1_reserved.start()), p2i(g1_reserved.end()),
2923 HeapRegion::GrainBytes);
2924 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX);
2925 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX
2926 G1PPRL_TYPE_H_FORMAT
2927 G1PPRL_ADDR_BASE_H_FORMAT
2928 G1PPRL_BYTE_H_FORMAT
2929 G1PPRL_BYTE_H_FORMAT
2930 G1PPRL_BYTE_H_FORMAT
2931 G1PPRL_DOUBLE_H_FORMAT
2932 G1PPRL_BYTE_H_FORMAT
2933 G1PPRL_STATE_H_FORMAT
2934 G1PPRL_BYTE_H_FORMAT,
2935 "type", "address-range",
2936 "used", "prev-live", "next-live", "gc-eff",
2937 "remset", "state", "code-roots");
2938 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX
2939 G1PPRL_TYPE_H_FORMAT
2940 G1PPRL_ADDR_BASE_H_FORMAT
2941 G1PPRL_BYTE_H_FORMAT
2942 G1PPRL_BYTE_H_FORMAT
2943 G1PPRL_BYTE_H_FORMAT
2944 G1PPRL_DOUBLE_H_FORMAT
2945 G1PPRL_BYTE_H_FORMAT
2946 G1PPRL_STATE_H_FORMAT
2947 G1PPRL_BYTE_H_FORMAT,
2948 "", "",
2949 "(bytes)", "(bytes)", "(bytes)", "(bytes/ms)",
2950 "(bytes)", "", "(bytes)");
2951 }
2952
2953 bool G1PrintRegionLivenessInfoClosure::do_heap_region(HeapRegion* r) {
2954 if (!log_is_enabled(Trace, gc, liveness)) {
2955 return false;
2956 }
2957
2958 const char* type = r->get_type_str();
2959 HeapWord* bottom = r->bottom();
2960 HeapWord* end = r->end();
2961 size_t capacity_bytes = r->capacity();
2962 size_t used_bytes = r->used();
2963 size_t prev_live_bytes = r->live_bytes();
2964 size_t next_live_bytes = r->next_live_bytes();
2965 double gc_eff = r->gc_efficiency();
2966 size_t remset_bytes = r->rem_set()->mem_size();
2967 size_t strong_code_roots_bytes = r->rem_set()->strong_code_roots_mem_size();
2968 const char* remset_type = r->rem_set()->get_short_state_str();
2969
2970 _total_used_bytes += used_bytes;
2971 _total_capacity_bytes += capacity_bytes;
2972 _total_prev_live_bytes += prev_live_bytes;
2973 _total_next_live_bytes += next_live_bytes;
2974 _total_remset_bytes += remset_bytes;
2975 _total_strong_code_roots_bytes += strong_code_roots_bytes;
2976
2977 // Print a line for this particular region.
2978 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX
2979 G1PPRL_TYPE_FORMAT
2980 G1PPRL_ADDR_BASE_FORMAT
2981 G1PPRL_BYTE_FORMAT
2982 G1PPRL_BYTE_FORMAT
2983 G1PPRL_BYTE_FORMAT
2984 G1PPRL_DOUBLE_FORMAT
2985 G1PPRL_BYTE_FORMAT
2986 G1PPRL_STATE_FORMAT
2987 G1PPRL_BYTE_FORMAT,
2988 type, p2i(bottom), p2i(end),
2989 used_bytes, prev_live_bytes, next_live_bytes, gc_eff,
2990 remset_bytes, remset_type, strong_code_roots_bytes);
2991
2992 return false;
2993 }
2994
2995 G1PrintRegionLivenessInfoClosure::~G1PrintRegionLivenessInfoClosure() {
2996 if (!log_is_enabled(Trace, gc, liveness)) {
2997 return;
2998 }
2999
3000 // add static memory usages to remembered set sizes
3001 _total_remset_bytes += HeapRegionRemSet::fl_mem_size() + HeapRegionRemSet::static_mem_size();
3002 // Print the footer of the output.
3003 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX);
3004 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX
3005 " SUMMARY"
3006 G1PPRL_SUM_MB_FORMAT("capacity")
3007 G1PPRL_SUM_MB_PERC_FORMAT("used")
3008 G1PPRL_SUM_MB_PERC_FORMAT("prev-live")
3009 G1PPRL_SUM_MB_PERC_FORMAT("next-live")
3010 G1PPRL_SUM_MB_FORMAT("remset")
3011 G1PPRL_SUM_MB_FORMAT("code-roots"),
3012 bytes_to_mb(_total_capacity_bytes),
3013 bytes_to_mb(_total_used_bytes),
3014 percent_of(_total_used_bytes, _total_capacity_bytes),
3015 bytes_to_mb(_total_prev_live_bytes),
3016 percent_of(_total_prev_live_bytes, _total_capacity_bytes),
3017 bytes_to_mb(_total_next_live_bytes),
3018 percent_of(_total_next_live_bytes, _total_capacity_bytes),
3019 bytes_to_mb(_total_remset_bytes),
3020 bytes_to_mb(_total_strong_code_roots_bytes));
3021 }