1 /*
2 * Copyright (c) 2001, 2016, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/metadataOnStackMark.hpp"
27 #include "classfile/symbolTable.hpp"
28 #include "code/codeCache.hpp"
29 #include "gc/g1/concurrentMarkThread.inline.hpp"
30 #include "gc/g1/g1CollectedHeap.inline.hpp"
31 #include "gc/g1/g1CollectorState.hpp"
32 #include "gc/g1/g1ConcurrentMark.inline.hpp"
33 #include "gc/g1/g1HeapVerifier.hpp"
34 #include "gc/g1/g1OopClosures.inline.hpp"
35 #include "gc/g1/g1CardLiveData.inline.hpp"
36 #include "gc/g1/g1Policy.hpp"
37 #include "gc/g1/g1StringDedup.hpp"
38 #include "gc/g1/heapRegion.inline.hpp"
39 #include "gc/g1/heapRegionRemSet.hpp"
40 #include "gc/g1/heapRegionSet.inline.hpp"
41 #include "gc/g1/suspendibleThreadSet.hpp"
42 #include "gc/shared/gcId.hpp"
43 #include "gc/shared/gcTimer.hpp"
44 #include "gc/shared/gcTrace.hpp"
45 #include "gc/shared/gcTraceTime.inline.hpp"
46 #include "gc/shared/genOopClosures.inline.hpp"
47 #include "gc/shared/referencePolicy.hpp"
48 #include "gc/shared/strongRootsScope.hpp"
49 #include "gc/shared/taskqueue.inline.hpp"
50 #include "gc/shared/vmGCOperations.hpp"
51 #include "logging/log.hpp"
52 #include "memory/allocation.hpp"
53 #include "memory/resourceArea.hpp"
54 #include "oops/oop.inline.hpp"
55 #include "runtime/atomic.inline.hpp"
56 #include "runtime/handles.inline.hpp"
57 #include "runtime/java.hpp"
58 #include "runtime/prefetch.inline.hpp"
59 #include "services/memTracker.hpp"
60 #include "utilities/growableArray.hpp"
61
62 // Concurrent marking bit map wrapper
63
64 G1CMBitMapRO::G1CMBitMapRO(int shifter) :
65 _bm(),
66 _shifter(shifter) {
67 _bmStartWord = 0;
68 _bmWordSize = 0;
69 }
70
71 HeapWord* G1CMBitMapRO::getNextMarkedWordAddress(const HeapWord* addr,
72 const HeapWord* limit) const {
73 // First we must round addr *up* to a possible object boundary.
74 addr = (HeapWord*)align_size_up((intptr_t)addr,
75 HeapWordSize << _shifter);
76 size_t addrOffset = heapWordToOffset(addr);
77 assert(limit != NULL, "limit must not be NULL");
78 size_t limitOffset = heapWordToOffset(limit);
79 size_t nextOffset = _bm.get_next_one_offset(addrOffset, limitOffset);
80 HeapWord* nextAddr = offsetToHeapWord(nextOffset);
81 assert(nextAddr >= addr, "get_next_one postcondition");
82 assert(nextAddr == limit || isMarked(nextAddr),
83 "get_next_one postcondition");
84 return nextAddr;
85 }
86
87 #ifndef PRODUCT
88 bool G1CMBitMapRO::covers(MemRegion heap_rs) const {
89 // assert(_bm.map() == _virtual_space.low(), "map inconsistency");
90 assert(((size_t)_bm.size() * ((size_t)1 << _shifter)) == _bmWordSize,
91 "size inconsistency");
92 return _bmStartWord == (HeapWord*)(heap_rs.start()) &&
93 _bmWordSize == heap_rs.word_size();
94 }
95 #endif
96
97 void G1CMBitMapRO::print_on_error(outputStream* st, const char* prefix) const {
98 _bm.print_on_error(st, prefix);
99 }
100
101 size_t G1CMBitMap::compute_size(size_t heap_size) {
102 return ReservedSpace::allocation_align_size_up(heap_size / mark_distance());
103 }
104
105 size_t G1CMBitMap::mark_distance() {
106 return MinObjAlignmentInBytes * BitsPerByte;
107 }
108
109 void G1CMBitMap::initialize(MemRegion heap, G1RegionToSpaceMapper* storage) {
110 _bmStartWord = heap.start();
111 _bmWordSize = heap.word_size();
112
113 _bm = BitMapView((BitMap::bm_word_t*) storage->reserved().start(), _bmWordSize >> _shifter);
114
115 storage->set_mapping_changed_listener(&_listener);
116 }
117
118 void G1CMBitMapMappingChangedListener::on_commit(uint start_region, size_t num_regions, bool zero_filled) {
119 if (zero_filled) {
120 return;
121 }
122 // We need to clear the bitmap on commit, removing any existing information.
123 MemRegion mr(G1CollectedHeap::heap()->bottom_addr_for_region(start_region), num_regions * HeapRegion::GrainWords);
124 _bm->clear_range(mr);
125 }
126
127 void G1CMBitMap::clear_range(MemRegion mr) {
128 mr.intersection(MemRegion(_bmStartWord, _bmWordSize));
129 assert(!mr.is_empty(), "unexpected empty region");
130 // convert address range into offset range
131 _bm.at_put_range(heapWordToOffset(mr.start()),
132 heapWordToOffset(mr.end()), false);
133 }
134
135 G1CMMarkStack::G1CMMarkStack(G1ConcurrentMark* cm) :
136 _base(NULL), _cm(cm)
137 {}
138
139 bool G1CMMarkStack::allocate(size_t capacity) {
140 // allocate a stack of the requisite depth
141 ReservedSpace rs(ReservedSpace::allocation_align_size_up(capacity * sizeof(oop)));
142 if (!rs.is_reserved()) {
143 log_warning(gc)("ConcurrentMark MarkStack allocation failure");
144 return false;
145 }
146 MemTracker::record_virtual_memory_type((address)rs.base(), mtGC);
147 if (!_virtual_space.initialize(rs, rs.size())) {
148 log_warning(gc)("ConcurrentMark MarkStack backing store failure");
149 // Release the virtual memory reserved for the marking stack
150 rs.release();
151 return false;
152 }
153 assert(_virtual_space.committed_size() == rs.size(),
154 "Didn't reserve backing store for all of G1ConcurrentMark stack?");
155 _base = (oop*) _virtual_space.low();
156 setEmpty();
157 _capacity = (jint) capacity;
158 _saved_index = -1;
159 _should_expand = false;
160 return true;
161 }
162
163 void G1CMMarkStack::expand() {
164 // Called, during remark, if we've overflown the marking stack during marking.
165 assert(isEmpty(), "stack should been emptied while handling overflow");
166 assert(_capacity <= (jint) MarkStackSizeMax, "stack bigger than permitted");
167 // Clear expansion flag
168 _should_expand = false;
169 if (_capacity == (jint) MarkStackSizeMax) {
170 log_trace(gc)("(benign) Can't expand marking stack capacity, at max size limit");
171 return;
172 }
173 // Double capacity if possible
174 jint new_capacity = MIN2(_capacity*2, (jint) MarkStackSizeMax);
175 // Do not give up existing stack until we have managed to
176 // get the double capacity that we desired.
177 ReservedSpace rs(ReservedSpace::allocation_align_size_up(new_capacity *
178 sizeof(oop)));
179 if (rs.is_reserved()) {
180 // Release the backing store associated with old stack
181 _virtual_space.release();
182 // Reinitialize virtual space for new stack
183 if (!_virtual_space.initialize(rs, rs.size())) {
184 fatal("Not enough swap for expanded marking stack capacity");
185 }
186 _base = (oop*)(_virtual_space.low());
187 _index = 0;
188 _capacity = new_capacity;
189 } else {
190 // Failed to double capacity, continue;
191 log_trace(gc)("(benign) Failed to expand marking stack capacity from " SIZE_FORMAT "K to " SIZE_FORMAT "K",
192 _capacity / K, new_capacity / K);
193 }
194 }
195
196 void G1CMMarkStack::set_should_expand() {
197 // If we're resetting the marking state because of an
198 // marking stack overflow, record that we should, if
199 // possible, expand the stack.
200 _should_expand = _cm->has_overflown();
201 }
202
203 G1CMMarkStack::~G1CMMarkStack() {
204 if (_base != NULL) {
205 _base = NULL;
206 _virtual_space.release();
207 }
208 }
209
210 void G1CMMarkStack::par_push_arr(oop* ptr_arr, int n) {
211 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
212 jint start = _index;
213 jint next_index = start + n;
214 if (next_index > _capacity) {
215 _overflow = true;
216 return;
217 }
218 // Otherwise.
219 _index = next_index;
220 for (int i = 0; i < n; i++) {
221 int ind = start + i;
222 assert(ind < _capacity, "By overflow test above.");
223 _base[ind] = ptr_arr[i];
224 }
225 }
226
227 bool G1CMMarkStack::par_pop_arr(oop* ptr_arr, int max, int* n) {
228 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
229 jint index = _index;
230 if (index == 0) {
231 *n = 0;
232 return false;
233 } else {
234 int k = MIN2(max, index);
235 jint new_ind = index - k;
236 for (int j = 0; j < k; j++) {
237 ptr_arr[j] = _base[new_ind + j];
238 }
239 _index = new_ind;
240 *n = k;
241 return true;
242 }
243 }
244
245 void G1CMMarkStack::note_start_of_gc() {
246 assert(_saved_index == -1,
247 "note_start_of_gc()/end_of_gc() bracketed incorrectly");
248 _saved_index = _index;
249 }
250
251 void G1CMMarkStack::note_end_of_gc() {
252 // This is intentionally a guarantee, instead of an assert. If we
253 // accidentally add something to the mark stack during GC, it
254 // will be a correctness issue so it's better if we crash. we'll
255 // only check this once per GC anyway, so it won't be a performance
256 // issue in any way.
257 guarantee(_saved_index == _index,
258 "saved index: %d index: %d", _saved_index, _index);
259 _saved_index = -1;
260 }
261
262 G1CMRootRegions::G1CMRootRegions() :
263 _cm(NULL), _scan_in_progress(false),
264 _should_abort(false), _claimed_survivor_index(0) { }
265
266 void G1CMRootRegions::init(const G1SurvivorRegions* survivors, G1ConcurrentMark* cm) {
267 _survivors = survivors;
268 _cm = cm;
269 }
270
271 void G1CMRootRegions::prepare_for_scan() {
272 assert(!scan_in_progress(), "pre-condition");
273
274 // Currently, only survivors can be root regions.
275 _claimed_survivor_index = 0;
276 _scan_in_progress = true;
277 _should_abort = false;
278 }
279
280 HeapRegion* G1CMRootRegions::claim_next() {
281 if (_should_abort) {
282 // If someone has set the should_abort flag, we return NULL to
283 // force the caller to bail out of their loop.
284 return NULL;
285 }
286
287 // Currently, only survivors can be root regions.
288 const GrowableArray<HeapRegion*>* survivor_regions = _survivors->regions();
289
290 int claimed_index = Atomic::add(1, &_claimed_survivor_index) - 1;
291 if (claimed_index < survivor_regions->length()) {
292 return survivor_regions->at(claimed_index);
293 }
294 return NULL;
295 }
296
297 void G1CMRootRegions::notify_scan_done() {
298 MutexLockerEx x(RootRegionScan_lock, Mutex::_no_safepoint_check_flag);
299 _scan_in_progress = false;
300 RootRegionScan_lock->notify_all();
301 }
302
303 void G1CMRootRegions::cancel_scan() {
304 notify_scan_done();
305 }
306
307 void G1CMRootRegions::scan_finished() {
308 assert(scan_in_progress(), "pre-condition");
309
310 // Currently, only survivors can be root regions.
311 if (!_should_abort) {
312 assert(_claimed_survivor_index >= 0, "otherwise comparison is invalid: %d", _claimed_survivor_index);
313 assert((uint)_claimed_survivor_index >= _survivors->length(),
314 "we should have claimed all survivors, claimed index = %u, length = %u",
315 (uint)_claimed_survivor_index, _survivors->length());
316 }
317
318 notify_scan_done();
319 }
320
321 bool G1CMRootRegions::wait_until_scan_finished() {
322 if (!scan_in_progress()) return false;
323
324 {
325 MutexLockerEx x(RootRegionScan_lock, Mutex::_no_safepoint_check_flag);
326 while (scan_in_progress()) {
327 RootRegionScan_lock->wait(Mutex::_no_safepoint_check_flag);
328 }
329 }
330 return true;
331 }
332
333 uint G1ConcurrentMark::scale_parallel_threads(uint n_par_threads) {
334 return MAX2((n_par_threads + 2) / 4, 1U);
335 }
336
337 G1ConcurrentMark::G1ConcurrentMark(G1CollectedHeap* g1h, G1RegionToSpaceMapper* prev_bitmap_storage, G1RegionToSpaceMapper* next_bitmap_storage) :
338 _g1h(g1h),
339 _markBitMap1(),
340 _markBitMap2(),
341 _parallel_marking_threads(0),
342 _max_parallel_marking_threads(0),
343 _sleep_factor(0.0),
344 _marking_task_overhead(1.0),
345 _cleanup_list("Cleanup List"),
346
347 _prevMarkBitMap(&_markBitMap1),
348 _nextMarkBitMap(&_markBitMap2),
349
350 _markStack(this),
351 // _finger set in set_non_marking_state
352
353 _max_worker_id(ParallelGCThreads),
354 // _active_tasks set in set_non_marking_state
355 // _tasks set inside the constructor
356 _task_queues(new G1CMTaskQueueSet((int) _max_worker_id)),
357 _terminator(ParallelTaskTerminator((int) _max_worker_id, _task_queues)),
358
359 _has_overflown(false),
360 _concurrent(false),
361 _has_aborted(false),
362 _restart_for_overflow(false),
363 _concurrent_marking_in_progress(false),
364 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
365 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()),
366
367 // _verbose_level set below
368
369 _init_times(),
370 _remark_times(), _remark_mark_times(), _remark_weak_ref_times(),
371 _cleanup_times(),
372 _total_counting_time(0.0),
373 _total_rs_scrub_time(0.0),
374
375 _parallel_workers(NULL),
376
377 _completed_initialization(false) {
378
379 _markBitMap1.initialize(g1h->reserved_region(), prev_bitmap_storage);
380 _markBitMap2.initialize(g1h->reserved_region(), next_bitmap_storage);
381
382 // Create & start a ConcurrentMark thread.
383 _cmThread = new ConcurrentMarkThread(this);
384 assert(cmThread() != NULL, "CM Thread should have been created");
385 assert(cmThread()->cm() != NULL, "CM Thread should refer to this cm");
386 if (_cmThread->osthread() == NULL) {
387 vm_shutdown_during_initialization("Could not create ConcurrentMarkThread");
388 }
389
390 assert(CGC_lock != NULL, "Where's the CGC_lock?");
391 assert(_markBitMap1.covers(g1h->reserved_region()), "_markBitMap1 inconsistency");
392 assert(_markBitMap2.covers(g1h->reserved_region()), "_markBitMap2 inconsistency");
393
394 SATBMarkQueueSet& satb_qs = JavaThread::satb_mark_queue_set();
395 satb_qs.set_buffer_size(G1SATBBufferSize);
396
397 _root_regions.init(_g1h->survivor(), this);
398
399 if (ConcGCThreads > ParallelGCThreads) {
400 log_warning(gc)("Can't have more ConcGCThreads (%u) than ParallelGCThreads (%u).",
401 ConcGCThreads, ParallelGCThreads);
402 return;
403 }
404 if (!FLAG_IS_DEFAULT(ConcGCThreads) && ConcGCThreads > 0) {
405 // Note: ConcGCThreads has precedence over G1MarkingOverheadPercent
406 // if both are set
407 _sleep_factor = 0.0;
408 _marking_task_overhead = 1.0;
409 } else if (G1MarkingOverheadPercent > 0) {
410 // We will calculate the number of parallel marking threads based
411 // on a target overhead with respect to the soft real-time goal
412 double marking_overhead = (double) G1MarkingOverheadPercent / 100.0;
413 double overall_cm_overhead =
414 (double) MaxGCPauseMillis * marking_overhead /
415 (double) GCPauseIntervalMillis;
416 double cpu_ratio = 1.0 / (double) os::processor_count();
417 double marking_thread_num = ceil(overall_cm_overhead / cpu_ratio);
418 double marking_task_overhead =
419 overall_cm_overhead / marking_thread_num *
420 (double) os::processor_count();
421 double sleep_factor =
422 (1.0 - marking_task_overhead) / marking_task_overhead;
423
424 FLAG_SET_ERGO(uint, ConcGCThreads, (uint) marking_thread_num);
425 _sleep_factor = sleep_factor;
426 _marking_task_overhead = marking_task_overhead;
427 } else {
428 // Calculate the number of parallel marking threads by scaling
429 // the number of parallel GC threads.
430 uint marking_thread_num = scale_parallel_threads(ParallelGCThreads);
431 FLAG_SET_ERGO(uint, ConcGCThreads, marking_thread_num);
432 _sleep_factor = 0.0;
433 _marking_task_overhead = 1.0;
434 }
435
436 assert(ConcGCThreads > 0, "Should have been set");
437 _parallel_marking_threads = ConcGCThreads;
438 _max_parallel_marking_threads = _parallel_marking_threads;
439
440 _parallel_workers = new WorkGang("G1 Marker",
441 _max_parallel_marking_threads, false, true);
442 if (_parallel_workers == NULL) {
443 vm_exit_during_initialization("Failed necessary allocation.");
444 } else {
445 _parallel_workers->initialize_workers();
446 }
447
448 if (FLAG_IS_DEFAULT(MarkStackSize)) {
449 size_t mark_stack_size =
450 MIN2(MarkStackSizeMax,
451 MAX2(MarkStackSize, (size_t) (parallel_marking_threads() * TASKQUEUE_SIZE)));
452 // Verify that the calculated value for MarkStackSize is in range.
453 // It would be nice to use the private utility routine from Arguments.
454 if (!(mark_stack_size >= 1 && mark_stack_size <= MarkStackSizeMax)) {
455 log_warning(gc)("Invalid value calculated for MarkStackSize (" SIZE_FORMAT "): "
456 "must be between 1 and " SIZE_FORMAT,
457 mark_stack_size, MarkStackSizeMax);
458 return;
459 }
460 FLAG_SET_ERGO(size_t, MarkStackSize, mark_stack_size);
461 } else {
462 // Verify MarkStackSize is in range.
463 if (FLAG_IS_CMDLINE(MarkStackSize)) {
464 if (FLAG_IS_DEFAULT(MarkStackSizeMax)) {
465 if (!(MarkStackSize >= 1 && MarkStackSize <= MarkStackSizeMax)) {
466 log_warning(gc)("Invalid value specified for MarkStackSize (" SIZE_FORMAT "): "
467 "must be between 1 and " SIZE_FORMAT,
468 MarkStackSize, MarkStackSizeMax);
469 return;
470 }
471 } else if (FLAG_IS_CMDLINE(MarkStackSizeMax)) {
472 if (!(MarkStackSize >= 1 && MarkStackSize <= MarkStackSizeMax)) {
473 log_warning(gc)("Invalid value specified for MarkStackSize (" SIZE_FORMAT ")"
474 " or for MarkStackSizeMax (" SIZE_FORMAT ")",
475 MarkStackSize, MarkStackSizeMax);
476 return;
477 }
478 }
479 }
480 }
481
482 if (!_markStack.allocate(MarkStackSize)) {
483 log_warning(gc)("Failed to allocate CM marking stack");
484 return;
485 }
486
487 _tasks = NEW_C_HEAP_ARRAY(G1CMTask*, _max_worker_id, mtGC);
488 _accum_task_vtime = NEW_C_HEAP_ARRAY(double, _max_worker_id, mtGC);
489
490 // so that the assertion in MarkingTaskQueue::task_queue doesn't fail
491 _active_tasks = _max_worker_id;
492
493 for (uint i = 0; i < _max_worker_id; ++i) {
494 G1CMTaskQueue* task_queue = new G1CMTaskQueue();
495 task_queue->initialize();
496 _task_queues->register_queue(i, task_queue);
497
498 _tasks[i] = new G1CMTask(i, this, task_queue, _task_queues);
499
500 _accum_task_vtime[i] = 0.0;
501 }
502
503 // so that the call below can read a sensible value
504 _heap_start = g1h->reserved_region().start();
505 set_non_marking_state();
506 _completed_initialization = true;
507 }
508
509 void G1ConcurrentMark::reset() {
510 // Starting values for these two. This should be called in a STW
511 // phase.
512 MemRegion reserved = _g1h->g1_reserved();
513 _heap_start = reserved.start();
514 _heap_end = reserved.end();
515
516 // Separated the asserts so that we know which one fires.
517 assert(_heap_start != NULL, "heap bounds should look ok");
518 assert(_heap_end != NULL, "heap bounds should look ok");
519 assert(_heap_start < _heap_end, "heap bounds should look ok");
520
521 // Reset all the marking data structures and any necessary flags
522 reset_marking_state();
523
524 // We do reset all of them, since different phases will use
525 // different number of active threads. So, it's easiest to have all
526 // of them ready.
527 for (uint i = 0; i < _max_worker_id; ++i) {
528 _tasks[i]->reset(_nextMarkBitMap);
529 }
530
531 // we need this to make sure that the flag is on during the evac
532 // pause with initial mark piggy-backed
533 set_concurrent_marking_in_progress();
534 }
535
536
537 void G1ConcurrentMark::reset_marking_state(bool clear_overflow) {
538 _markStack.set_should_expand();
539 _markStack.setEmpty(); // Also clears the _markStack overflow flag
540 if (clear_overflow) {
541 clear_has_overflown();
542 } else {
543 assert(has_overflown(), "pre-condition");
544 }
545 _finger = _heap_start;
546
547 for (uint i = 0; i < _max_worker_id; ++i) {
548 G1CMTaskQueue* queue = _task_queues->queue(i);
549 queue->set_empty();
550 }
551 }
552
553 void G1ConcurrentMark::set_concurrency(uint active_tasks) {
554 assert(active_tasks <= _max_worker_id, "we should not have more");
555
556 _active_tasks = active_tasks;
557 // Need to update the three data structures below according to the
558 // number of active threads for this phase.
559 _terminator = ParallelTaskTerminator((int) active_tasks, _task_queues);
560 _first_overflow_barrier_sync.set_n_workers((int) active_tasks);
561 _second_overflow_barrier_sync.set_n_workers((int) active_tasks);
562 }
563
564 void G1ConcurrentMark::set_concurrency_and_phase(uint active_tasks, bool concurrent) {
565 set_concurrency(active_tasks);
566
567 _concurrent = concurrent;
568 // We propagate this to all tasks, not just the active ones.
569 for (uint i = 0; i < _max_worker_id; ++i)
570 _tasks[i]->set_concurrent(concurrent);
571
572 if (concurrent) {
573 set_concurrent_marking_in_progress();
574 } else {
575 // We currently assume that the concurrent flag has been set to
576 // false before we start remark. At this point we should also be
577 // in a STW phase.
578 assert(!concurrent_marking_in_progress(), "invariant");
579 assert(out_of_regions(),
580 "only way to get here: _finger: " PTR_FORMAT ", _heap_end: " PTR_FORMAT,
581 p2i(_finger), p2i(_heap_end));
582 }
583 }
584
585 void G1ConcurrentMark::set_non_marking_state() {
586 // We set the global marking state to some default values when we're
587 // not doing marking.
588 reset_marking_state();
589 _active_tasks = 0;
590 clear_concurrent_marking_in_progress();
591 }
592
593 G1ConcurrentMark::~G1ConcurrentMark() {
594 // The G1ConcurrentMark instance is never freed.
595 ShouldNotReachHere();
596 }
597
598 class G1ClearBitMapTask : public AbstractGangTask {
599 public:
600 static size_t chunk_size() { return M; }
601
602 private:
603 // Heap region closure used for clearing the given mark bitmap.
604 class G1ClearBitmapHRClosure : public HeapRegionClosure {
605 private:
606 G1CMBitMap* _bitmap;
607 G1ConcurrentMark* _cm;
608 public:
609 G1ClearBitmapHRClosure(G1CMBitMap* bitmap, G1ConcurrentMark* cm) : HeapRegionClosure(), _cm(cm), _bitmap(bitmap) {
610 }
611
612 virtual bool doHeapRegion(HeapRegion* r) {
613 size_t const chunk_size_in_words = G1ClearBitMapTask::chunk_size() / HeapWordSize;
614
615 HeapWord* cur = r->bottom();
616 HeapWord* const end = r->end();
617
618 while (cur < end) {
619 MemRegion mr(cur, MIN2(cur + chunk_size_in_words, end));
620 _bitmap->clear_range(mr);
621
622 cur += chunk_size_in_words;
623
624 // Abort iteration if after yielding the marking has been aborted.
625 if (_cm != NULL && _cm->do_yield_check() && _cm->has_aborted()) {
626 return true;
627 }
628 // Repeat the asserts from before the start of the closure. We will do them
629 // as asserts here to minimize their overhead on the product. However, we
630 // will have them as guarantees at the beginning / end of the bitmap
631 // clearing to get some checking in the product.
632 assert(_cm == NULL || _cm->cmThread()->during_cycle(), "invariant");
633 assert(_cm == NULL || !G1CollectedHeap::heap()->collector_state()->mark_in_progress(), "invariant");
634 }
635 assert(cur == end, "Must have completed iteration over the bitmap for region %u.", r->hrm_index());
636
637 return false;
638 }
639 };
640
641 G1ClearBitmapHRClosure _cl;
642 HeapRegionClaimer _hr_claimer;
643 bool _suspendible; // If the task is suspendible, workers must join the STS.
644
645 public:
646 G1ClearBitMapTask(G1CMBitMap* bitmap, G1ConcurrentMark* cm, uint n_workers, bool suspendible) :
647 AbstractGangTask("G1 Clear Bitmap"),
648 _cl(bitmap, suspendible ? cm : NULL),
649 _hr_claimer(n_workers),
650 _suspendible(suspendible)
651 { }
652
653 void work(uint worker_id) {
654 SuspendibleThreadSetJoiner sts_join(_suspendible);
655 G1CollectedHeap::heap()->heap_region_par_iterate(&_cl, worker_id, &_hr_claimer, true);
656 }
657
658 bool is_complete() {
659 return _cl.complete();
660 }
661 };
662
663 void G1ConcurrentMark::clear_bitmap(G1CMBitMap* bitmap, WorkGang* workers, bool may_yield) {
664 assert(may_yield || SafepointSynchronize::is_at_safepoint(), "Non-yielding bitmap clear only allowed at safepoint.");
665
666 size_t const num_bytes_to_clear = (HeapRegion::GrainBytes * _g1h->num_regions()) / G1CMBitMap::heap_map_factor();
667 size_t const num_chunks = align_size_up(num_bytes_to_clear, G1ClearBitMapTask::chunk_size()) / G1ClearBitMapTask::chunk_size();
668
669 uint const num_workers = (uint)MIN2(num_chunks, (size_t)workers->active_workers());
670
671 G1ClearBitMapTask cl(bitmap, this, num_workers, may_yield);
672
673 log_debug(gc, ergo)("Running %s with %u workers for " SIZE_FORMAT " work units.", cl.name(), num_workers, num_chunks);
674 workers->run_task(&cl, num_workers);
675 guarantee(!may_yield || cl.is_complete(), "Must have completed iteration when not yielding.");
676 }
677
678 void G1ConcurrentMark::cleanup_for_next_mark() {
679 // Make sure that the concurrent mark thread looks to still be in
680 // the current cycle.
681 guarantee(cmThread()->during_cycle(), "invariant");
682
683 // We are finishing up the current cycle by clearing the next
684 // marking bitmap and getting it ready for the next cycle. During
685 // this time no other cycle can start. So, let's make sure that this
686 // is the case.
687 guarantee(!_g1h->collector_state()->mark_in_progress(), "invariant");
688
689 clear_bitmap(_nextMarkBitMap, _parallel_workers, true);
690
691 // Clear the live count data. If the marking has been aborted, the abort()
692 // call already did that.
693 if (!has_aborted()) {
694 clear_live_data(_parallel_workers);
695 DEBUG_ONLY(verify_live_data_clear());
696 }
697
698 // Repeat the asserts from above.
699 guarantee(cmThread()->during_cycle(), "invariant");
700 guarantee(!_g1h->collector_state()->mark_in_progress(), "invariant");
701 }
702
703 void G1ConcurrentMark::clear_prev_bitmap(WorkGang* workers) {
704 assert(SafepointSynchronize::is_at_safepoint(), "Should only clear the entire prev bitmap at a safepoint.");
705 clear_bitmap((G1CMBitMap*)_prevMarkBitMap, workers, false);
706 }
707
708 class CheckBitmapClearHRClosure : public HeapRegionClosure {
709 G1CMBitMap* _bitmap;
710 bool _error;
711 public:
712 CheckBitmapClearHRClosure(G1CMBitMap* bitmap) : _bitmap(bitmap) {
713 }
714
715 virtual bool doHeapRegion(HeapRegion* r) {
716 // This closure can be called concurrently to the mutator, so we must make sure
717 // that the result of the getNextMarkedWordAddress() call is compared to the
718 // value passed to it as limit to detect any found bits.
719 // end never changes in G1.
720 HeapWord* end = r->end();
721 return _bitmap->getNextMarkedWordAddress(r->bottom(), end) != end;
722 }
723 };
724
725 bool G1ConcurrentMark::nextMarkBitmapIsClear() {
726 CheckBitmapClearHRClosure cl(_nextMarkBitMap);
727 _g1h->heap_region_iterate(&cl);
728 return cl.complete();
729 }
730
731 class NoteStartOfMarkHRClosure: public HeapRegionClosure {
732 public:
733 bool doHeapRegion(HeapRegion* r) {
734 r->note_start_of_marking();
735 return false;
736 }
737 };
738
739 void G1ConcurrentMark::checkpointRootsInitialPre() {
740 G1CollectedHeap* g1h = G1CollectedHeap::heap();
741 G1Policy* g1p = g1h->g1_policy();
742
743 _has_aborted = false;
744
745 // Initialize marking structures. This has to be done in a STW phase.
746 reset();
747
748 // For each region note start of marking.
749 NoteStartOfMarkHRClosure startcl;
750 g1h->heap_region_iterate(&startcl);
751 }
752
753
754 void G1ConcurrentMark::checkpointRootsInitialPost() {
755 G1CollectedHeap* g1h = G1CollectedHeap::heap();
756
757 // Start Concurrent Marking weak-reference discovery.
758 ReferenceProcessor* rp = g1h->ref_processor_cm();
759 // enable ("weak") refs discovery
760 rp->enable_discovery();
761 rp->setup_policy(false); // snapshot the soft ref policy to be used in this cycle
762
763 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
764 // This is the start of the marking cycle, we're expected all
765 // threads to have SATB queues with active set to false.
766 satb_mq_set.set_active_all_threads(true, /* new active value */
767 false /* expected_active */);
768
769 _root_regions.prepare_for_scan();
770
771 // update_g1_committed() will be called at the end of an evac pause
772 // when marking is on. So, it's also called at the end of the
773 // initial-mark pause to update the heap end, if the heap expands
774 // during it. No need to call it here.
775 }
776
777 /*
778 * Notice that in the next two methods, we actually leave the STS
779 * during the barrier sync and join it immediately afterwards. If we
780 * do not do this, the following deadlock can occur: one thread could
781 * be in the barrier sync code, waiting for the other thread to also
782 * sync up, whereas another one could be trying to yield, while also
783 * waiting for the other threads to sync up too.
784 *
785 * Note, however, that this code is also used during remark and in
786 * this case we should not attempt to leave / enter the STS, otherwise
787 * we'll either hit an assert (debug / fastdebug) or deadlock
788 * (product). So we should only leave / enter the STS if we are
789 * operating concurrently.
790 *
791 * Because the thread that does the sync barrier has left the STS, it
792 * is possible to be suspended for a Full GC or an evacuation pause
793 * could occur. This is actually safe, since the entering the sync
794 * barrier is one of the last things do_marking_step() does, and it
795 * doesn't manipulate any data structures afterwards.
796 */
797
798 void G1ConcurrentMark::enter_first_sync_barrier(uint worker_id) {
799 bool barrier_aborted;
800 {
801 SuspendibleThreadSetLeaver sts_leave(concurrent());
802 barrier_aborted = !_first_overflow_barrier_sync.enter();
803 }
804
805 // at this point everyone should have synced up and not be doing any
806 // more work
807
808 if (barrier_aborted) {
809 // If the barrier aborted we ignore the overflow condition and
810 // just abort the whole marking phase as quickly as possible.
811 return;
812 }
813
814 // If we're executing the concurrent phase of marking, reset the marking
815 // state; otherwise the marking state is reset after reference processing,
816 // during the remark pause.
817 // If we reset here as a result of an overflow during the remark we will
818 // see assertion failures from any subsequent set_concurrency_and_phase()
819 // calls.
820 if (concurrent()) {
821 // let the task associated with with worker 0 do this
822 if (worker_id == 0) {
823 // task 0 is responsible for clearing the global data structures
824 // We should be here because of an overflow. During STW we should
825 // not clear the overflow flag since we rely on it being true when
826 // we exit this method to abort the pause and restart concurrent
827 // marking.
828 reset_marking_state(true /* clear_overflow */);
829
830 log_info(gc, marking)("Concurrent Mark reset for overflow");
831 }
832 }
833
834 // after this, each task should reset its own data structures then
835 // then go into the second barrier
836 }
837
838 void G1ConcurrentMark::enter_second_sync_barrier(uint worker_id) {
839 SuspendibleThreadSetLeaver sts_leave(concurrent());
840 _second_overflow_barrier_sync.enter();
841
842 // at this point everything should be re-initialized and ready to go
843 }
844
845 class G1CMConcurrentMarkingTask: public AbstractGangTask {
846 private:
847 G1ConcurrentMark* _cm;
848 ConcurrentMarkThread* _cmt;
849
850 public:
851 void work(uint worker_id) {
852 assert(Thread::current()->is_ConcurrentGC_thread(),
853 "this should only be done by a conc GC thread");
854 ResourceMark rm;
855
856 double start_vtime = os::elapsedVTime();
857
858 {
859 SuspendibleThreadSetJoiner sts_join;
860
861 assert(worker_id < _cm->active_tasks(), "invariant");
862 G1CMTask* the_task = _cm->task(worker_id);
863 the_task->record_start_time();
864 if (!_cm->has_aborted()) {
865 do {
866 double start_vtime_sec = os::elapsedVTime();
867 double mark_step_duration_ms = G1ConcMarkStepDurationMillis;
868
869 the_task->do_marking_step(mark_step_duration_ms,
870 true /* do_termination */,
871 false /* is_serial*/);
872
873 double end_vtime_sec = os::elapsedVTime();
874 double elapsed_vtime_sec = end_vtime_sec - start_vtime_sec;
875 _cm->clear_has_overflown();
876
877 _cm->do_yield_check();
878
879 jlong sleep_time_ms;
880 if (!_cm->has_aborted() && the_task->has_aborted()) {
881 sleep_time_ms =
882 (jlong) (elapsed_vtime_sec * _cm->sleep_factor() * 1000.0);
883 {
884 SuspendibleThreadSetLeaver sts_leave;
885 os::sleep(Thread::current(), sleep_time_ms, false);
886 }
887 }
888 } while (!_cm->has_aborted() && the_task->has_aborted());
889 }
890 the_task->record_end_time();
891 guarantee(!the_task->has_aborted() || _cm->has_aborted(), "invariant");
892 }
893
894 double end_vtime = os::elapsedVTime();
895 _cm->update_accum_task_vtime(worker_id, end_vtime - start_vtime);
896 }
897
898 G1CMConcurrentMarkingTask(G1ConcurrentMark* cm,
899 ConcurrentMarkThread* cmt) :
900 AbstractGangTask("Concurrent Mark"), _cm(cm), _cmt(cmt) { }
901
902 ~G1CMConcurrentMarkingTask() { }
903 };
904
905 // Calculates the number of active workers for a concurrent
906 // phase.
907 uint G1ConcurrentMark::calc_parallel_marking_threads() {
908 uint n_conc_workers = 0;
909 if (!UseDynamicNumberOfGCThreads ||
910 (!FLAG_IS_DEFAULT(ConcGCThreads) &&
911 !ForceDynamicNumberOfGCThreads)) {
912 n_conc_workers = max_parallel_marking_threads();
913 } else {
914 n_conc_workers =
915 AdaptiveSizePolicy::calc_default_active_workers(
916 max_parallel_marking_threads(),
917 1, /* Minimum workers */
918 parallel_marking_threads(),
919 Threads::number_of_non_daemon_threads());
920 // Don't scale down "n_conc_workers" by scale_parallel_threads() because
921 // that scaling has already gone into "_max_parallel_marking_threads".
922 }
923 assert(n_conc_workers > 0, "Always need at least 1");
924 return n_conc_workers;
925 }
926
927 void G1ConcurrentMark::scanRootRegion(HeapRegion* hr) {
928 // Currently, only survivors can be root regions.
929 assert(hr->next_top_at_mark_start() == hr->bottom(), "invariant");
930 G1RootRegionScanClosure cl(_g1h, this);
931
932 const uintx interval = PrefetchScanIntervalInBytes;
933 HeapWord* curr = hr->bottom();
934 const HeapWord* end = hr->top();
935 while (curr < end) {
936 Prefetch::read(curr, interval);
937 oop obj = oop(curr);
938 int size = obj->oop_iterate_size(&cl);
939 assert(size == obj->size(), "sanity");
940 curr += size;
941 }
942 }
943
944 class G1CMRootRegionScanTask : public AbstractGangTask {
945 private:
946 G1ConcurrentMark* _cm;
947
948 public:
949 G1CMRootRegionScanTask(G1ConcurrentMark* cm) :
950 AbstractGangTask("Root Region Scan"), _cm(cm) { }
951
952 void work(uint worker_id) {
953 assert(Thread::current()->is_ConcurrentGC_thread(),
954 "this should only be done by a conc GC thread");
955
956 G1CMRootRegions* root_regions = _cm->root_regions();
957 HeapRegion* hr = root_regions->claim_next();
958 while (hr != NULL) {
959 _cm->scanRootRegion(hr);
960 hr = root_regions->claim_next();
961 }
962 }
963 };
964
965 void G1ConcurrentMark::scan_root_regions() {
966 // scan_in_progress() will have been set to true only if there was
967 // at least one root region to scan. So, if it's false, we
968 // should not attempt to do any further work.
969 if (root_regions()->scan_in_progress()) {
970 assert(!has_aborted(), "Aborting before root region scanning is finished not supported.");
971
972 _parallel_marking_threads = calc_parallel_marking_threads();
973 assert(parallel_marking_threads() <= max_parallel_marking_threads(),
974 "Maximum number of marking threads exceeded");
975 uint active_workers = MAX2(1U, parallel_marking_threads());
976
977 G1CMRootRegionScanTask task(this);
978 _parallel_workers->set_active_workers(active_workers);
979 _parallel_workers->run_task(&task);
980
981 // It's possible that has_aborted() is true here without actually
982 // aborting the survivor scan earlier. This is OK as it's
983 // mainly used for sanity checking.
984 root_regions()->scan_finished();
985 }
986 }
987
988 void G1ConcurrentMark::concurrent_cycle_start() {
989 _gc_timer_cm->register_gc_start();
990
991 _gc_tracer_cm->report_gc_start(GCCause::_no_gc /* first parameter is not used */, _gc_timer_cm->gc_start());
992
993 _g1h->trace_heap_before_gc(_gc_tracer_cm);
994 }
995
996 void G1ConcurrentMark::concurrent_cycle_end() {
997 _g1h->trace_heap_after_gc(_gc_tracer_cm);
998
999 if (has_aborted()) {
1000 _gc_tracer_cm->report_concurrent_mode_failure();
1001 }
1002
1003 _gc_timer_cm->register_gc_end();
1004
1005 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
1006 }
1007
1008 void G1ConcurrentMark::mark_from_roots() {
1009 // we might be tempted to assert that:
1010 // assert(asynch == !SafepointSynchronize::is_at_safepoint(),
1011 // "inconsistent argument?");
1012 // However that wouldn't be right, because it's possible that
1013 // a safepoint is indeed in progress as a younger generation
1014 // stop-the-world GC happens even as we mark in this generation.
1015
1016 _restart_for_overflow = false;
1017
1018 // _g1h has _n_par_threads
1019 _parallel_marking_threads = calc_parallel_marking_threads();
1020 assert(parallel_marking_threads() <= max_parallel_marking_threads(),
1021 "Maximum number of marking threads exceeded");
1022
1023 uint active_workers = MAX2(1U, parallel_marking_threads());
1024 assert(active_workers > 0, "Should have been set");
1025
1026 // Parallel task terminator is set in "set_concurrency_and_phase()"
1027 set_concurrency_and_phase(active_workers, true /* concurrent */);
1028
1029 G1CMConcurrentMarkingTask markingTask(this, cmThread());
1030 _parallel_workers->set_active_workers(active_workers);
1031 _parallel_workers->run_task(&markingTask);
1032 print_stats();
1033 }
1034
1035 void G1ConcurrentMark::checkpointRootsFinal(bool clear_all_soft_refs) {
1036 // world is stopped at this checkpoint
1037 assert(SafepointSynchronize::is_at_safepoint(),
1038 "world should be stopped");
1039
1040 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1041
1042 // If a full collection has happened, we shouldn't do this.
1043 if (has_aborted()) {
1044 g1h->collector_state()->set_mark_in_progress(false); // So bitmap clearing isn't confused
1045 return;
1046 }
1047
1048 if (VerifyDuringGC) {
1049 HandleMark hm; // handle scope
1050 g1h->prepare_for_verify();
1051 Universe::verify(VerifyOption_G1UsePrevMarking, "During GC (before)");
1052 }
1053 g1h->verifier()->check_bitmaps("Remark Start");
1054
1055 G1Policy* g1p = g1h->g1_policy();
1056 g1p->record_concurrent_mark_remark_start();
1057
1058 double start = os::elapsedTime();
1059
1060 checkpointRootsFinalWork();
1061
1062 double mark_work_end = os::elapsedTime();
1063
1064 weakRefsWork(clear_all_soft_refs);
1065
1066 if (has_overflown()) {
1067 // Oops. We overflowed. Restart concurrent marking.
1068 _restart_for_overflow = true;
1069
1070 // Verify the heap w.r.t. the previous marking bitmap.
1071 if (VerifyDuringGC) {
1072 HandleMark hm; // handle scope
1073 g1h->prepare_for_verify();
1074 Universe::verify(VerifyOption_G1UsePrevMarking, "During GC (overflow)");
1075 }
1076
1077 // Clear the marking state because we will be restarting
1078 // marking due to overflowing the global mark stack.
1079 reset_marking_state();
1080 } else {
1081 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
1082 // We're done with marking.
1083 // This is the end of the marking cycle, we're expected all
1084 // threads to have SATB queues with active set to true.
1085 satb_mq_set.set_active_all_threads(false, /* new active value */
1086 true /* expected_active */);
1087
1088 if (VerifyDuringGC) {
1089 HandleMark hm; // handle scope
1090 g1h->prepare_for_verify();
1091 Universe::verify(VerifyOption_G1UseNextMarking, "During GC (after)");
1092 }
1093 g1h->verifier()->check_bitmaps("Remark End");
1094 assert(!restart_for_overflow(), "sanity");
1095 // Completely reset the marking state since marking completed
1096 set_non_marking_state();
1097 }
1098
1099 // Expand the marking stack, if we have to and if we can.
1100 if (_markStack.should_expand()) {
1101 _markStack.expand();
1102 }
1103
1104 // Statistics
1105 double now = os::elapsedTime();
1106 _remark_mark_times.add((mark_work_end - start) * 1000.0);
1107 _remark_weak_ref_times.add((now - mark_work_end) * 1000.0);
1108 _remark_times.add((now - start) * 1000.0);
1109
1110 g1p->record_concurrent_mark_remark_end();
1111
1112 G1CMIsAliveClosure is_alive(g1h);
1113 _gc_tracer_cm->report_object_count_after_gc(&is_alive);
1114 }
1115
1116 class G1NoteEndOfConcMarkClosure : public HeapRegionClosure {
1117 G1CollectedHeap* _g1;
1118 size_t _freed_bytes;
1119 FreeRegionList* _local_cleanup_list;
1120 uint _old_regions_removed;
1121 uint _humongous_regions_removed;
1122 HRRSCleanupTask* _hrrs_cleanup_task;
1123
1124 public:
1125 G1NoteEndOfConcMarkClosure(G1CollectedHeap* g1,
1126 FreeRegionList* local_cleanup_list,
1127 HRRSCleanupTask* hrrs_cleanup_task) :
1128 _g1(g1),
1129 _freed_bytes(0),
1130 _local_cleanup_list(local_cleanup_list),
1131 _old_regions_removed(0),
1132 _humongous_regions_removed(0),
1133 _hrrs_cleanup_task(hrrs_cleanup_task) { }
1134
1135 size_t freed_bytes() { return _freed_bytes; }
1136 const uint old_regions_removed() { return _old_regions_removed; }
1137 const uint humongous_regions_removed() { return _humongous_regions_removed; }
1138
1139 bool doHeapRegion(HeapRegion *hr) {
1140 if (hr->is_archive()) {
1141 return false;
1142 }
1143 _g1->reset_gc_time_stamps(hr);
1144 hr->note_end_of_marking();
1145
1146 if (hr->used() > 0 && hr->max_live_bytes() == 0 && !hr->is_young()) {
1147 _freed_bytes += hr->used();
1148 hr->set_containing_set(NULL);
1149 if (hr->is_humongous()) {
1150 _humongous_regions_removed++;
1151 _g1->free_humongous_region(hr, _local_cleanup_list, true);
1152 } else {
1153 _old_regions_removed++;
1154 _g1->free_region(hr, _local_cleanup_list, true);
1155 }
1156 } else {
1157 hr->rem_set()->do_cleanup_work(_hrrs_cleanup_task);
1158 }
1159
1160 return false;
1161 }
1162 };
1163
1164 class G1ParNoteEndTask: public AbstractGangTask {
1165 friend class G1NoteEndOfConcMarkClosure;
1166
1167 protected:
1168 G1CollectedHeap* _g1h;
1169 FreeRegionList* _cleanup_list;
1170 HeapRegionClaimer _hrclaimer;
1171
1172 public:
1173 G1ParNoteEndTask(G1CollectedHeap* g1h, FreeRegionList* cleanup_list, uint n_workers) :
1174 AbstractGangTask("G1 note end"), _g1h(g1h), _cleanup_list(cleanup_list), _hrclaimer(n_workers) {
1175 }
1176
1177 void work(uint worker_id) {
1178 FreeRegionList local_cleanup_list("Local Cleanup List");
1179 HRRSCleanupTask hrrs_cleanup_task;
1180 G1NoteEndOfConcMarkClosure g1_note_end(_g1h, &local_cleanup_list,
1181 &hrrs_cleanup_task);
1182 _g1h->heap_region_par_iterate(&g1_note_end, worker_id, &_hrclaimer);
1183 assert(g1_note_end.complete(), "Shouldn't have yielded!");
1184
1185 // Now update the lists
1186 _g1h->remove_from_old_sets(g1_note_end.old_regions_removed(), g1_note_end.humongous_regions_removed());
1187 {
1188 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
1189 _g1h->decrement_summary_bytes(g1_note_end.freed_bytes());
1190
1191 // If we iterate over the global cleanup list at the end of
1192 // cleanup to do this printing we will not guarantee to only
1193 // generate output for the newly-reclaimed regions (the list
1194 // might not be empty at the beginning of cleanup; we might
1195 // still be working on its previous contents). So we do the
1196 // printing here, before we append the new regions to the global
1197 // cleanup list.
1198
1199 G1HRPrinter* hr_printer = _g1h->hr_printer();
1200 if (hr_printer->is_active()) {
1201 FreeRegionListIterator iter(&local_cleanup_list);
1202 while (iter.more_available()) {
1203 HeapRegion* hr = iter.get_next();
1204 hr_printer->cleanup(hr);
1205 }
1206 }
1207
1208 _cleanup_list->add_ordered(&local_cleanup_list);
1209 assert(local_cleanup_list.is_empty(), "post-condition");
1210
1211 HeapRegionRemSet::finish_cleanup_task(&hrrs_cleanup_task);
1212 }
1213 }
1214 };
1215
1216 void G1ConcurrentMark::cleanup() {
1217 // world is stopped at this checkpoint
1218 assert(SafepointSynchronize::is_at_safepoint(),
1219 "world should be stopped");
1220 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1221
1222 // If a full collection has happened, we shouldn't do this.
1223 if (has_aborted()) {
1224 g1h->collector_state()->set_mark_in_progress(false); // So bitmap clearing isn't confused
1225 return;
1226 }
1227
1228 g1h->verifier()->verify_region_sets_optional();
1229
1230 if (VerifyDuringGC) {
1231 HandleMark hm; // handle scope
1232 g1h->prepare_for_verify();
1233 Universe::verify(VerifyOption_G1UsePrevMarking, "During GC (before)");
1234 }
1235 g1h->verifier()->check_bitmaps("Cleanup Start");
1236
1237 G1Policy* g1p = g1h->g1_policy();
1238 g1p->record_concurrent_mark_cleanup_start();
1239
1240 double start = os::elapsedTime();
1241
1242 HeapRegionRemSet::reset_for_cleanup_tasks();
1243
1244 {
1245 GCTraceTime(Debug, gc)("Finalize Live Data");
1246 finalize_live_data();
1247 }
1248
1249 if (VerifyDuringGC) {
1250 GCTraceTime(Debug, gc)("Verify Live Data");
1251 verify_live_data();
1252 }
1253
1254 g1h->collector_state()->set_mark_in_progress(false);
1255
1256 double count_end = os::elapsedTime();
1257 double this_final_counting_time = (count_end - start);
1258 _total_counting_time += this_final_counting_time;
1259
1260 if (log_is_enabled(Trace, gc, liveness)) {
1261 G1PrintRegionLivenessInfoClosure cl("Post-Marking");
1262 _g1h->heap_region_iterate(&cl);
1263 }
1264
1265 // Install newly created mark bitMap as "prev".
1266 swapMarkBitMaps();
1267
1268 g1h->reset_gc_time_stamp();
1269
1270 uint n_workers = _g1h->workers()->active_workers();
1271
1272 // Note end of marking in all heap regions.
1273 G1ParNoteEndTask g1_par_note_end_task(g1h, &_cleanup_list, n_workers);
1274 g1h->workers()->run_task(&g1_par_note_end_task);
1275 g1h->check_gc_time_stamps();
1276
1277 if (!cleanup_list_is_empty()) {
1278 // The cleanup list is not empty, so we'll have to process it
1279 // concurrently. Notify anyone else that might be wanting free
1280 // regions that there will be more free regions coming soon.
1281 g1h->set_free_regions_coming();
1282 }
1283
1284 // call below, since it affects the metric by which we sort the heap
1285 // regions.
1286 if (G1ScrubRemSets) {
1287 double rs_scrub_start = os::elapsedTime();
1288 g1h->scrub_rem_set();
1289 _total_rs_scrub_time += (os::elapsedTime() - rs_scrub_start);
1290 }
1291
1292 // this will also free any regions totally full of garbage objects,
1293 // and sort the regions.
1294 g1h->g1_policy()->record_concurrent_mark_cleanup_end();
1295
1296 // Statistics.
1297 double end = os::elapsedTime();
1298 _cleanup_times.add((end - start) * 1000.0);
1299
1300 // Clean up will have freed any regions completely full of garbage.
1301 // Update the soft reference policy with the new heap occupancy.
1302 Universe::update_heap_info_at_gc();
1303
1304 if (VerifyDuringGC) {
1305 HandleMark hm; // handle scope
1306 g1h->prepare_for_verify();
1307 Universe::verify(VerifyOption_G1UsePrevMarking, "During GC (after)");
1308 }
1309
1310 g1h->verifier()->check_bitmaps("Cleanup End");
1311
1312 g1h->verifier()->verify_region_sets_optional();
1313
1314 // We need to make this be a "collection" so any collection pause that
1315 // races with it goes around and waits for completeCleanup to finish.
1316 g1h->increment_total_collections();
1317
1318 // Clean out dead classes and update Metaspace sizes.
1319 if (ClassUnloadingWithConcurrentMark) {
1320 ClassLoaderDataGraph::purge();
1321 }
1322 MetaspaceGC::compute_new_size();
1323
1324 // We reclaimed old regions so we should calculate the sizes to make
1325 // sure we update the old gen/space data.
1326 g1h->g1mm()->update_sizes();
1327 g1h->allocation_context_stats().update_after_mark();
1328 }
1329
1330 void G1ConcurrentMark::complete_cleanup() {
1331 if (has_aborted()) return;
1332
1333 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1334
1335 _cleanup_list.verify_optional();
1336 FreeRegionList tmp_free_list("Tmp Free List");
1337
1338 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [complete cleanup] : "
1339 "cleanup list has %u entries",
1340 _cleanup_list.length());
1341
1342 // No one else should be accessing the _cleanup_list at this point,
1343 // so it is not necessary to take any locks
1344 while (!_cleanup_list.is_empty()) {
1345 HeapRegion* hr = _cleanup_list.remove_region(true /* from_head */);
1346 assert(hr != NULL, "Got NULL from a non-empty list");
1347 hr->par_clear();
1348 tmp_free_list.add_ordered(hr);
1349
1350 // Instead of adding one region at a time to the secondary_free_list,
1351 // we accumulate them in the local list and move them a few at a
1352 // time. This also cuts down on the number of notify_all() calls
1353 // we do during this process. We'll also append the local list when
1354 // _cleanup_list is empty (which means we just removed the last
1355 // region from the _cleanup_list).
1356 if ((tmp_free_list.length() % G1SecondaryFreeListAppendLength == 0) ||
1357 _cleanup_list.is_empty()) {
1358 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [complete cleanup] : "
1359 "appending %u entries to the secondary_free_list, "
1360 "cleanup list still has %u entries",
1361 tmp_free_list.length(),
1362 _cleanup_list.length());
1363
1364 {
1365 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
1366 g1h->secondary_free_list_add(&tmp_free_list);
1367 SecondaryFreeList_lock->notify_all();
1368 }
1369 #ifndef PRODUCT
1370 if (G1StressConcRegionFreeing) {
1371 for (uintx i = 0; i < G1StressConcRegionFreeingDelayMillis; ++i) {
1372 os::sleep(Thread::current(), (jlong) 1, false);
1373 }
1374 }
1375 #endif
1376 }
1377 }
1378 assert(tmp_free_list.is_empty(), "post-condition");
1379 }
1380
1381 // Supporting Object and Oop closures for reference discovery
1382 // and processing in during marking
1383
1384 bool G1CMIsAliveClosure::do_object_b(oop obj) {
1385 HeapWord* addr = (HeapWord*)obj;
1386 return addr != NULL &&
1387 (!_g1->is_in_g1_reserved(addr) || !_g1->is_obj_ill(obj));
1388 }
1389
1390 // 'Keep Alive' oop closure used by both serial parallel reference processing.
1391 // Uses the G1CMTask associated with a worker thread (for serial reference
1392 // processing the G1CMTask for worker 0 is used) to preserve (mark) and
1393 // trace referent objects.
1394 //
1395 // Using the G1CMTask and embedded local queues avoids having the worker
1396 // threads operating on the global mark stack. This reduces the risk
1397 // of overflowing the stack - which we would rather avoid at this late
1398 // state. Also using the tasks' local queues removes the potential
1399 // of the workers interfering with each other that could occur if
1400 // operating on the global stack.
1401
1402 class G1CMKeepAliveAndDrainClosure: public OopClosure {
1403 G1ConcurrentMark* _cm;
1404 G1CMTask* _task;
1405 int _ref_counter_limit;
1406 int _ref_counter;
1407 bool _is_serial;
1408 public:
1409 G1CMKeepAliveAndDrainClosure(G1ConcurrentMark* cm, G1CMTask* task, bool is_serial) :
1410 _cm(cm), _task(task), _is_serial(is_serial),
1411 _ref_counter_limit(G1RefProcDrainInterval) {
1412 assert(_ref_counter_limit > 0, "sanity");
1413 assert(!_is_serial || _task->worker_id() == 0, "only task 0 for serial code");
1414 _ref_counter = _ref_counter_limit;
1415 }
1416
1417 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
1418 virtual void do_oop( oop* p) { do_oop_work(p); }
1419
1420 template <class T> void do_oop_work(T* p) {
1421 if (!_cm->has_overflown()) {
1422 oop obj = oopDesc::load_decode_heap_oop(p);
1423 _task->deal_with_reference(obj);
1424 _ref_counter--;
1425
1426 if (_ref_counter == 0) {
1427 // We have dealt with _ref_counter_limit references, pushing them
1428 // and objects reachable from them on to the local stack (and
1429 // possibly the global stack). Call G1CMTask::do_marking_step() to
1430 // process these entries.
1431 //
1432 // We call G1CMTask::do_marking_step() in a loop, which we'll exit if
1433 // there's nothing more to do (i.e. we're done with the entries that
1434 // were pushed as a result of the G1CMTask::deal_with_reference() calls
1435 // above) or we overflow.
1436 //
1437 // Note: G1CMTask::do_marking_step() can set the G1CMTask::has_aborted()
1438 // flag while there may still be some work to do. (See the comment at
1439 // the beginning of G1CMTask::do_marking_step() for those conditions -
1440 // one of which is reaching the specified time target.) It is only
1441 // when G1CMTask::do_marking_step() returns without setting the
1442 // has_aborted() flag that the marking step has completed.
1443 do {
1444 double mark_step_duration_ms = G1ConcMarkStepDurationMillis;
1445 _task->do_marking_step(mark_step_duration_ms,
1446 false /* do_termination */,
1447 _is_serial);
1448 } while (_task->has_aborted() && !_cm->has_overflown());
1449 _ref_counter = _ref_counter_limit;
1450 }
1451 }
1452 }
1453 };
1454
1455 // 'Drain' oop closure used by both serial and parallel reference processing.
1456 // Uses the G1CMTask associated with a given worker thread (for serial
1457 // reference processing the G1CMtask for worker 0 is used). Calls the
1458 // do_marking_step routine, with an unbelievably large timeout value,
1459 // to drain the marking data structures of the remaining entries
1460 // added by the 'keep alive' oop closure above.
1461
1462 class G1CMDrainMarkingStackClosure: public VoidClosure {
1463 G1ConcurrentMark* _cm;
1464 G1CMTask* _task;
1465 bool _is_serial;
1466 public:
1467 G1CMDrainMarkingStackClosure(G1ConcurrentMark* cm, G1CMTask* task, bool is_serial) :
1468 _cm(cm), _task(task), _is_serial(is_serial) {
1469 assert(!_is_serial || _task->worker_id() == 0, "only task 0 for serial code");
1470 }
1471
1472 void do_void() {
1473 do {
1474 // We call G1CMTask::do_marking_step() to completely drain the local
1475 // and global marking stacks of entries pushed by the 'keep alive'
1476 // oop closure (an instance of G1CMKeepAliveAndDrainClosure above).
1477 //
1478 // G1CMTask::do_marking_step() is called in a loop, which we'll exit
1479 // if there's nothing more to do (i.e. we've completely drained the
1480 // entries that were pushed as a a result of applying the 'keep alive'
1481 // closure to the entries on the discovered ref lists) or we overflow
1482 // the global marking stack.
1483 //
1484 // Note: G1CMTask::do_marking_step() can set the G1CMTask::has_aborted()
1485 // flag while there may still be some work to do. (See the comment at
1486 // the beginning of G1CMTask::do_marking_step() for those conditions -
1487 // one of which is reaching the specified time target.) It is only
1488 // when G1CMTask::do_marking_step() returns without setting the
1489 // has_aborted() flag that the marking step has completed.
1490
1491 _task->do_marking_step(1000000000.0 /* something very large */,
1492 true /* do_termination */,
1493 _is_serial);
1494 } while (_task->has_aborted() && !_cm->has_overflown());
1495 }
1496 };
1497
1498 // Implementation of AbstractRefProcTaskExecutor for parallel
1499 // reference processing at the end of G1 concurrent marking
1500
1501 class G1CMRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
1502 private:
1503 G1CollectedHeap* _g1h;
1504 G1ConcurrentMark* _cm;
1505 WorkGang* _workers;
1506 uint _active_workers;
1507
1508 public:
1509 G1CMRefProcTaskExecutor(G1CollectedHeap* g1h,
1510 G1ConcurrentMark* cm,
1511 WorkGang* workers,
1512 uint n_workers) :
1513 _g1h(g1h), _cm(cm),
1514 _workers(workers), _active_workers(n_workers) { }
1515
1516 // Executes the given task using concurrent marking worker threads.
1517 virtual void execute(ProcessTask& task);
1518 virtual void execute(EnqueueTask& task);
1519 };
1520
1521 class G1CMRefProcTaskProxy: public AbstractGangTask {
1522 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
1523 ProcessTask& _proc_task;
1524 G1CollectedHeap* _g1h;
1525 G1ConcurrentMark* _cm;
1526
1527 public:
1528 G1CMRefProcTaskProxy(ProcessTask& proc_task,
1529 G1CollectedHeap* g1h,
1530 G1ConcurrentMark* cm) :
1531 AbstractGangTask("Process reference objects in parallel"),
1532 _proc_task(proc_task), _g1h(g1h), _cm(cm) {
1533 ReferenceProcessor* rp = _g1h->ref_processor_cm();
1534 assert(rp->processing_is_mt(), "shouldn't be here otherwise");
1535 }
1536
1537 virtual void work(uint worker_id) {
1538 ResourceMark rm;
1539 HandleMark hm;
1540 G1CMTask* task = _cm->task(worker_id);
1541 G1CMIsAliveClosure g1_is_alive(_g1h);
1542 G1CMKeepAliveAndDrainClosure g1_par_keep_alive(_cm, task, false /* is_serial */);
1543 G1CMDrainMarkingStackClosure g1_par_drain(_cm, task, false /* is_serial */);
1544
1545 _proc_task.work(worker_id, g1_is_alive, g1_par_keep_alive, g1_par_drain);
1546 }
1547 };
1548
1549 void G1CMRefProcTaskExecutor::execute(ProcessTask& proc_task) {
1550 assert(_workers != NULL, "Need parallel worker threads.");
1551 assert(_g1h->ref_processor_cm()->processing_is_mt(), "processing is not MT");
1552
1553 G1CMRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _cm);
1554
1555 // We need to reset the concurrency level before each
1556 // proxy task execution, so that the termination protocol
1557 // and overflow handling in G1CMTask::do_marking_step() knows
1558 // how many workers to wait for.
1559 _cm->set_concurrency(_active_workers);
1560 _workers->run_task(&proc_task_proxy);
1561 }
1562
1563 class G1CMRefEnqueueTaskProxy: public AbstractGangTask {
1564 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
1565 EnqueueTask& _enq_task;
1566
1567 public:
1568 G1CMRefEnqueueTaskProxy(EnqueueTask& enq_task) :
1569 AbstractGangTask("Enqueue reference objects in parallel"),
1570 _enq_task(enq_task) { }
1571
1572 virtual void work(uint worker_id) {
1573 _enq_task.work(worker_id);
1574 }
1575 };
1576
1577 void G1CMRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
1578 assert(_workers != NULL, "Need parallel worker threads.");
1579 assert(_g1h->ref_processor_cm()->processing_is_mt(), "processing is not MT");
1580
1581 G1CMRefEnqueueTaskProxy enq_task_proxy(enq_task);
1582
1583 // Not strictly necessary but...
1584 //
1585 // We need to reset the concurrency level before each
1586 // proxy task execution, so that the termination protocol
1587 // and overflow handling in G1CMTask::do_marking_step() knows
1588 // how many workers to wait for.
1589 _cm->set_concurrency(_active_workers);
1590 _workers->run_task(&enq_task_proxy);
1591 }
1592
1593 void G1ConcurrentMark::weakRefsWorkParallelPart(BoolObjectClosure* is_alive, bool purged_classes) {
1594 G1CollectedHeap::heap()->parallel_cleaning(is_alive, true, true, purged_classes);
1595 }
1596
1597 void G1ConcurrentMark::weakRefsWork(bool clear_all_soft_refs) {
1598 if (has_overflown()) {
1599 // Skip processing the discovered references if we have
1600 // overflown the global marking stack. Reference objects
1601 // only get discovered once so it is OK to not
1602 // de-populate the discovered reference lists. We could have,
1603 // but the only benefit would be that, when marking restarts,
1604 // less reference objects are discovered.
1605 return;
1606 }
1607
1608 ResourceMark rm;
1609 HandleMark hm;
1610
1611 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1612
1613 // Is alive closure.
1614 G1CMIsAliveClosure g1_is_alive(g1h);
1615
1616 // Inner scope to exclude the cleaning of the string and symbol
1617 // tables from the displayed time.
1618 {
1619 GCTraceTime(Debug, gc, phases) trace("Reference Processing", _gc_timer_cm);
1620
1621 ReferenceProcessor* rp = g1h->ref_processor_cm();
1622
1623 // See the comment in G1CollectedHeap::ref_processing_init()
1624 // about how reference processing currently works in G1.
1625
1626 // Set the soft reference policy
1627 rp->setup_policy(clear_all_soft_refs);
1628 assert(_markStack.isEmpty(), "mark stack should be empty");
1629
1630 // Instances of the 'Keep Alive' and 'Complete GC' closures used
1631 // in serial reference processing. Note these closures are also
1632 // used for serially processing (by the the current thread) the
1633 // JNI references during parallel reference processing.
1634 //
1635 // These closures do not need to synchronize with the worker
1636 // threads involved in parallel reference processing as these
1637 // instances are executed serially by the current thread (e.g.
1638 // reference processing is not multi-threaded and is thus
1639 // performed by the current thread instead of a gang worker).
1640 //
1641 // The gang tasks involved in parallel reference processing create
1642 // their own instances of these closures, which do their own
1643 // synchronization among themselves.
1644 G1CMKeepAliveAndDrainClosure g1_keep_alive(this, task(0), true /* is_serial */);
1645 G1CMDrainMarkingStackClosure g1_drain_mark_stack(this, task(0), true /* is_serial */);
1646
1647 // We need at least one active thread. If reference processing
1648 // is not multi-threaded we use the current (VMThread) thread,
1649 // otherwise we use the work gang from the G1CollectedHeap and
1650 // we utilize all the worker threads we can.
1651 bool processing_is_mt = rp->processing_is_mt();
1652 uint active_workers = (processing_is_mt ? g1h->workers()->active_workers() : 1U);
1653 active_workers = MAX2(MIN2(active_workers, _max_worker_id), 1U);
1654
1655 // Parallel processing task executor.
1656 G1CMRefProcTaskExecutor par_task_executor(g1h, this,
1657 g1h->workers(), active_workers);
1658 AbstractRefProcTaskExecutor* executor = (processing_is_mt ? &par_task_executor : NULL);
1659
1660 // Set the concurrency level. The phase was already set prior to
1661 // executing the remark task.
1662 set_concurrency(active_workers);
1663
1664 // Set the degree of MT processing here. If the discovery was done MT,
1665 // the number of threads involved during discovery could differ from
1666 // the number of active workers. This is OK as long as the discovered
1667 // Reference lists are balanced (see balance_all_queues() and balance_queues()).
1668 rp->set_active_mt_degree(active_workers);
1669
1670 // Process the weak references.
1671 const ReferenceProcessorStats& stats =
1672 rp->process_discovered_references(&g1_is_alive,
1673 &g1_keep_alive,
1674 &g1_drain_mark_stack,
1675 executor,
1676 _gc_timer_cm);
1677 _gc_tracer_cm->report_gc_reference_stats(stats);
1678
1679 // The do_oop work routines of the keep_alive and drain_marking_stack
1680 // oop closures will set the has_overflown flag if we overflow the
1681 // global marking stack.
1682
1683 assert(_markStack.overflow() || _markStack.isEmpty(),
1684 "mark stack should be empty (unless it overflowed)");
1685
1686 if (_markStack.overflow()) {
1687 // This should have been done already when we tried to push an
1688 // entry on to the global mark stack. But let's do it again.
1689 set_has_overflown();
1690 }
1691
1692 assert(rp->num_q() == active_workers, "why not");
1693
1694 rp->enqueue_discovered_references(executor);
1695
1696 rp->verify_no_references_recorded();
1697 assert(!rp->discovery_enabled(), "Post condition");
1698 }
1699
1700 if (has_overflown()) {
1701 // We can not trust g1_is_alive if the marking stack overflowed
1702 return;
1703 }
1704
1705 assert(_markStack.isEmpty(), "Marking should have completed");
1706
1707 // Unload Klasses, String, Symbols, Code Cache, etc.
1708 if (ClassUnloadingWithConcurrentMark) {
1709 bool purged_classes;
1710
1711 {
1712 GCTraceTime(Debug, gc, phases) trace("System Dictionary Unloading", _gc_timer_cm);
1713 purged_classes = SystemDictionary::do_unloading(&g1_is_alive, false /* Defer klass cleaning */);
1714 }
1715
1716 {
1717 GCTraceTime(Debug, gc, phases) trace("Parallel Unloading", _gc_timer_cm);
1718 weakRefsWorkParallelPart(&g1_is_alive, purged_classes);
1719 }
1720 }
1721
1722 if (G1StringDedup::is_enabled()) {
1723 GCTraceTime(Debug, gc, phases) trace("String Deduplication Unlink", _gc_timer_cm);
1724 G1StringDedup::unlink(&g1_is_alive);
1725 }
1726 }
1727
1728 void G1ConcurrentMark::swapMarkBitMaps() {
1729 G1CMBitMapRO* temp = _prevMarkBitMap;
1730 _prevMarkBitMap = (G1CMBitMapRO*)_nextMarkBitMap;
1731 _nextMarkBitMap = (G1CMBitMap*) temp;
1732 }
1733
1734 // Closure for marking entries in SATB buffers.
1735 class G1CMSATBBufferClosure : public SATBBufferClosure {
1736 private:
1737 G1CMTask* _task;
1738 G1CollectedHeap* _g1h;
1739
1740 // This is very similar to G1CMTask::deal_with_reference, but with
1741 // more relaxed requirements for the argument, so this must be more
1742 // circumspect about treating the argument as an object.
1743 void do_entry(void* entry) const {
1744 _task->increment_refs_reached();
1745 HeapRegion* hr = _g1h->heap_region_containing(entry);
1746 if (entry < hr->next_top_at_mark_start()) {
1747 // Until we get here, we don't know whether entry refers to a valid
1748 // object; it could instead have been a stale reference.
1749 oop obj = static_cast<oop>(entry);
1750 assert(obj->is_oop(true /* ignore mark word */),
1751 "Invalid oop in SATB buffer: " PTR_FORMAT, p2i(obj));
1752 _task->make_reference_grey(obj);
1753 }
1754 }
1755
1756 public:
1757 G1CMSATBBufferClosure(G1CMTask* task, G1CollectedHeap* g1h)
1758 : _task(task), _g1h(g1h) { }
1759
1760 virtual void do_buffer(void** buffer, size_t size) {
1761 for (size_t i = 0; i < size; ++i) {
1762 do_entry(buffer[i]);
1763 }
1764 }
1765 };
1766
1767 class G1RemarkThreadsClosure : public ThreadClosure {
1768 G1CMSATBBufferClosure _cm_satb_cl;
1769 G1CMOopClosure _cm_cl;
1770 MarkingCodeBlobClosure _code_cl;
1771 int _thread_parity;
1772
1773 public:
1774 G1RemarkThreadsClosure(G1CollectedHeap* g1h, G1CMTask* task) :
1775 _cm_satb_cl(task, g1h),
1776 _cm_cl(g1h, g1h->concurrent_mark(), task),
1777 _code_cl(&_cm_cl, !CodeBlobToOopClosure::FixRelocations),
1778 _thread_parity(Threads::thread_claim_parity()) {}
1779
1780 void do_thread(Thread* thread) {
1781 if (thread->is_Java_thread()) {
1782 if (thread->claim_oops_do(true, _thread_parity)) {
1783 JavaThread* jt = (JavaThread*)thread;
1784
1785 // In theory it should not be neccessary to explicitly walk the nmethods to find roots for concurrent marking
1786 // however the liveness of oops reachable from nmethods have very complex lifecycles:
1787 // * Alive if on the stack of an executing method
1788 // * Weakly reachable otherwise
1789 // Some objects reachable from nmethods, such as the class loader (or klass_holder) of the receiver should be
1790 // live by the SATB invariant but other oops recorded in nmethods may behave differently.
1791 jt->nmethods_do(&_code_cl);
1792
1793 jt->satb_mark_queue().apply_closure_and_empty(&_cm_satb_cl);
1794 }
1795 } else if (thread->is_VM_thread()) {
1796 if (thread->claim_oops_do(true, _thread_parity)) {
1797 JavaThread::satb_mark_queue_set().shared_satb_queue()->apply_closure_and_empty(&_cm_satb_cl);
1798 }
1799 }
1800 }
1801 };
1802
1803 class G1CMRemarkTask: public AbstractGangTask {
1804 private:
1805 G1ConcurrentMark* _cm;
1806 public:
1807 void work(uint worker_id) {
1808 // Since all available tasks are actually started, we should
1809 // only proceed if we're supposed to be active.
1810 if (worker_id < _cm->active_tasks()) {
1811 G1CMTask* task = _cm->task(worker_id);
1812 task->record_start_time();
1813 {
1814 ResourceMark rm;
1815 HandleMark hm;
1816
1817 G1RemarkThreadsClosure threads_f(G1CollectedHeap::heap(), task);
1818 Threads::threads_do(&threads_f);
1819 }
1820
1821 do {
1822 task->do_marking_step(1000000000.0 /* something very large */,
1823 true /* do_termination */,
1824 false /* is_serial */);
1825 } while (task->has_aborted() && !_cm->has_overflown());
1826 // If we overflow, then we do not want to restart. We instead
1827 // want to abort remark and do concurrent marking again.
1828 task->record_end_time();
1829 }
1830 }
1831
1832 G1CMRemarkTask(G1ConcurrentMark* cm, uint active_workers) :
1833 AbstractGangTask("Par Remark"), _cm(cm) {
1834 _cm->terminator()->reset_for_reuse(active_workers);
1835 }
1836 };
1837
1838 void G1ConcurrentMark::checkpointRootsFinalWork() {
1839 ResourceMark rm;
1840 HandleMark hm;
1841 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1842
1843 GCTraceTime(Debug, gc, phases) trace("Finalize Marking", _gc_timer_cm);
1844
1845 g1h->ensure_parsability(false);
1846
1847 // this is remark, so we'll use up all active threads
1848 uint active_workers = g1h->workers()->active_workers();
1849 set_concurrency_and_phase(active_workers, false /* concurrent */);
1850 // Leave _parallel_marking_threads at it's
1851 // value originally calculated in the G1ConcurrentMark
1852 // constructor and pass values of the active workers
1853 // through the gang in the task.
1854
1855 {
1856 StrongRootsScope srs(active_workers);
1857
1858 G1CMRemarkTask remarkTask(this, active_workers);
1859 // We will start all available threads, even if we decide that the
1860 // active_workers will be fewer. The extra ones will just bail out
1861 // immediately.
1862 g1h->workers()->run_task(&remarkTask);
1863 }
1864
1865 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
1866 guarantee(has_overflown() ||
1867 satb_mq_set.completed_buffers_num() == 0,
1868 "Invariant: has_overflown = %s, num buffers = " SIZE_FORMAT,
1869 BOOL_TO_STR(has_overflown()),
1870 satb_mq_set.completed_buffers_num());
1871
1872 print_stats();
1873 }
1874
1875 void G1ConcurrentMark::clearRangePrevBitmap(MemRegion mr) {
1876 // Note we are overriding the read-only view of the prev map here, via
1877 // the cast.
1878 ((G1CMBitMap*)_prevMarkBitMap)->clear_range(mr);
1879 }
1880
1881 HeapRegion*
1882 G1ConcurrentMark::claim_region(uint worker_id) {
1883 // "checkpoint" the finger
1884 HeapWord* finger = _finger;
1885
1886 // _heap_end will not change underneath our feet; it only changes at
1887 // yield points.
1888 while (finger < _heap_end) {
1889 assert(_g1h->is_in_g1_reserved(finger), "invariant");
1890
1891 HeapRegion* curr_region = _g1h->heap_region_containing(finger);
1892
1893 // Above heap_region_containing may return NULL as we always scan claim
1894 // until the end of the heap. In this case, just jump to the next region.
1895 HeapWord* end = curr_region != NULL ? curr_region->end() : finger + HeapRegion::GrainWords;
1896
1897 // Is the gap between reading the finger and doing the CAS too long?
1898 HeapWord* res = (HeapWord*) Atomic::cmpxchg_ptr(end, &_finger, finger);
1899 if (res == finger && curr_region != NULL) {
1900 // we succeeded
1901 HeapWord* bottom = curr_region->bottom();
1902 HeapWord* limit = curr_region->next_top_at_mark_start();
1903
1904 // notice that _finger == end cannot be guaranteed here since,
1905 // someone else might have moved the finger even further
1906 assert(_finger >= end, "the finger should have moved forward");
1907
1908 if (limit > bottom) {
1909 return curr_region;
1910 } else {
1911 assert(limit == bottom,
1912 "the region limit should be at bottom");
1913 // we return NULL and the caller should try calling
1914 // claim_region() again.
1915 return NULL;
1916 }
1917 } else {
1918 assert(_finger > finger, "the finger should have moved forward");
1919 // read it again
1920 finger = _finger;
1921 }
1922 }
1923
1924 return NULL;
1925 }
1926
1927 #ifndef PRODUCT
1928 class VerifyNoCSetOops VALUE_OBJ_CLASS_SPEC {
1929 private:
1930 G1CollectedHeap* _g1h;
1931 const char* _phase;
1932 int _info;
1933
1934 public:
1935 VerifyNoCSetOops(const char* phase, int info = -1) :
1936 _g1h(G1CollectedHeap::heap()),
1937 _phase(phase),
1938 _info(info)
1939 { }
1940
1941 void operator()(oop obj) const {
1942 guarantee(obj->is_oop(),
1943 "Non-oop " PTR_FORMAT ", phase: %s, info: %d",
1944 p2i(obj), _phase, _info);
1945 guarantee(!_g1h->obj_in_cs(obj),
1946 "obj: " PTR_FORMAT " in CSet, phase: %s, info: %d",
1947 p2i(obj), _phase, _info);
1948 }
1949 };
1950
1951 void G1ConcurrentMark::verify_no_cset_oops() {
1952 assert(SafepointSynchronize::is_at_safepoint(), "should be at a safepoint");
1953 if (!G1CollectedHeap::heap()->collector_state()->mark_in_progress()) {
1954 return;
1955 }
1956
1957 // Verify entries on the global mark stack
1958 _markStack.iterate(VerifyNoCSetOops("Stack"));
1959
1960 // Verify entries on the task queues
1961 for (uint i = 0; i < _max_worker_id; ++i) {
1962 G1CMTaskQueue* queue = _task_queues->queue(i);
1963 queue->iterate(VerifyNoCSetOops("Queue", i));
1964 }
1965
1966 // Verify the global finger
1967 HeapWord* global_finger = finger();
1968 if (global_finger != NULL && global_finger < _heap_end) {
1969 // Since we always iterate over all regions, we might get a NULL HeapRegion
1970 // here.
1971 HeapRegion* global_hr = _g1h->heap_region_containing(global_finger);
1972 guarantee(global_hr == NULL || global_finger == global_hr->bottom(),
1973 "global finger: " PTR_FORMAT " region: " HR_FORMAT,
1974 p2i(global_finger), HR_FORMAT_PARAMS(global_hr));
1975 }
1976
1977 // Verify the task fingers
1978 assert(parallel_marking_threads() <= _max_worker_id, "sanity");
1979 for (uint i = 0; i < parallel_marking_threads(); ++i) {
1980 G1CMTask* task = _tasks[i];
1981 HeapWord* task_finger = task->finger();
1982 if (task_finger != NULL && task_finger < _heap_end) {
1983 // See above note on the global finger verification.
1984 HeapRegion* task_hr = _g1h->heap_region_containing(task_finger);
1985 guarantee(task_hr == NULL || task_finger == task_hr->bottom() ||
1986 !task_hr->in_collection_set(),
1987 "task finger: " PTR_FORMAT " region: " HR_FORMAT,
1988 p2i(task_finger), HR_FORMAT_PARAMS(task_hr));
1989 }
1990 }
1991 }
1992 #endif // PRODUCT
1993 void G1ConcurrentMark::create_live_data() {
1994 _g1h->g1_rem_set()->create_card_live_data(_parallel_workers, _nextMarkBitMap);
1995 }
1996
1997 void G1ConcurrentMark::finalize_live_data() {
1998 _g1h->g1_rem_set()->finalize_card_live_data(_g1h->workers(), _nextMarkBitMap);
1999 }
2000
2001 void G1ConcurrentMark::verify_live_data() {
2002 _g1h->g1_rem_set()->verify_card_live_data(_g1h->workers(), _nextMarkBitMap);
2003 }
2004
2005 void G1ConcurrentMark::clear_live_data(WorkGang* workers) {
2006 _g1h->g1_rem_set()->clear_card_live_data(workers);
2007 }
2008
2009 #ifdef ASSERT
2010 void G1ConcurrentMark::verify_live_data_clear() {
2011 _g1h->g1_rem_set()->verify_card_live_data_is_clear();
2012 }
2013 #endif
2014
2015 void G1ConcurrentMark::print_stats() {
2016 if (!log_is_enabled(Debug, gc, stats)) {
2017 return;
2018 }
2019 log_debug(gc, stats)("---------------------------------------------------------------------");
2020 for (size_t i = 0; i < _active_tasks; ++i) {
2021 _tasks[i]->print_stats();
2022 log_debug(gc, stats)("---------------------------------------------------------------------");
2023 }
2024 }
2025
2026 void G1ConcurrentMark::abort() {
2027 if (!cmThread()->during_cycle() || _has_aborted) {
2028 // We haven't started a concurrent cycle or we have already aborted it. No need to do anything.
2029 return;
2030 }
2031
2032 // Clear all marks in the next bitmap for the next marking cycle. This will allow us to skip the next
2033 // concurrent bitmap clearing.
2034 {
2035 GCTraceTime(Debug, gc)("Clear Next Bitmap");
2036 clear_bitmap(_nextMarkBitMap, _g1h->workers(), false);
2037 }
2038 // Note we cannot clear the previous marking bitmap here
2039 // since VerifyDuringGC verifies the objects marked during
2040 // a full GC against the previous bitmap.
2041
2042 {
2043 GCTraceTime(Debug, gc)("Clear Live Data");
2044 clear_live_data(_g1h->workers());
2045 }
2046 DEBUG_ONLY({
2047 GCTraceTime(Debug, gc)("Verify Live Data Clear");
2048 verify_live_data_clear();
2049 })
2050 // Empty mark stack
2051 reset_marking_state();
2052 for (uint i = 0; i < _max_worker_id; ++i) {
2053 _tasks[i]->clear_region_fields();
2054 }
2055 _first_overflow_barrier_sync.abort();
2056 _second_overflow_barrier_sync.abort();
2057 _has_aborted = true;
2058
2059 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
2060 satb_mq_set.abandon_partial_marking();
2061 // This can be called either during or outside marking, we'll read
2062 // the expected_active value from the SATB queue set.
2063 satb_mq_set.set_active_all_threads(
2064 false, /* new active value */
2065 satb_mq_set.is_active() /* expected_active */);
2066 }
2067
2068 static void print_ms_time_info(const char* prefix, const char* name,
2069 NumberSeq& ns) {
2070 log_trace(gc, marking)("%s%5d %12s: total time = %8.2f s (avg = %8.2f ms).",
2071 prefix, ns.num(), name, ns.sum()/1000.0, ns.avg());
2072 if (ns.num() > 0) {
2073 log_trace(gc, marking)("%s [std. dev = %8.2f ms, max = %8.2f ms]",
2074 prefix, ns.sd(), ns.maximum());
2075 }
2076 }
2077
2078 void G1ConcurrentMark::print_summary_info() {
2079 Log(gc, marking) log;
2080 if (!log.is_trace()) {
2081 return;
2082 }
2083
2084 log.trace(" Concurrent marking:");
2085 print_ms_time_info(" ", "init marks", _init_times);
2086 print_ms_time_info(" ", "remarks", _remark_times);
2087 {
2088 print_ms_time_info(" ", "final marks", _remark_mark_times);
2089 print_ms_time_info(" ", "weak refs", _remark_weak_ref_times);
2090
2091 }
2092 print_ms_time_info(" ", "cleanups", _cleanup_times);
2093 log.trace(" Finalize live data total time = %8.2f s (avg = %8.2f ms).",
2094 _total_counting_time, (_cleanup_times.num() > 0 ? _total_counting_time * 1000.0 / (double)_cleanup_times.num() : 0.0));
2095 if (G1ScrubRemSets) {
2096 log.trace(" RS scrub total time = %8.2f s (avg = %8.2f ms).",
2097 _total_rs_scrub_time, (_cleanup_times.num() > 0 ? _total_rs_scrub_time * 1000.0 / (double)_cleanup_times.num() : 0.0));
2098 }
2099 log.trace(" Total stop_world time = %8.2f s.",
2100 (_init_times.sum() + _remark_times.sum() + _cleanup_times.sum())/1000.0);
2101 log.trace(" Total concurrent time = %8.2f s (%8.2f s marking).",
2102 cmThread()->vtime_accum(), cmThread()->vtime_mark_accum());
2103 }
2104
2105 void G1ConcurrentMark::print_worker_threads_on(outputStream* st) const {
2106 _parallel_workers->print_worker_threads_on(st);
2107 }
2108
2109 void G1ConcurrentMark::threads_do(ThreadClosure* tc) const {
2110 _parallel_workers->threads_do(tc);
2111 }
2112
2113 void G1ConcurrentMark::print_on_error(outputStream* st) const {
2114 st->print_cr("Marking Bits (Prev, Next): (CMBitMap*) " PTR_FORMAT ", (CMBitMap*) " PTR_FORMAT,
2115 p2i(_prevMarkBitMap), p2i(_nextMarkBitMap));
2116 _prevMarkBitMap->print_on_error(st, " Prev Bits: ");
2117 _nextMarkBitMap->print_on_error(st, " Next Bits: ");
2118 }
2119
2120 // Closure for iteration over bitmaps
2121 class G1CMBitMapClosure : public BitMapClosure {
2122 private:
2123 // the bitmap that is being iterated over
2124 G1CMBitMap* _nextMarkBitMap;
2125 G1ConcurrentMark* _cm;
2126 G1CMTask* _task;
2127
2128 public:
2129 G1CMBitMapClosure(G1CMTask *task, G1ConcurrentMark* cm, G1CMBitMap* nextMarkBitMap) :
2130 _task(task), _cm(cm), _nextMarkBitMap(nextMarkBitMap) { }
2131
2132 bool do_bit(size_t offset) {
2133 HeapWord* addr = _nextMarkBitMap->offsetToHeapWord(offset);
2134 assert(_nextMarkBitMap->isMarked(addr), "invariant");
2135 assert( addr < _cm->finger(), "invariant");
2136 assert(addr >= _task->finger(), "invariant");
2137
2138 // We move that task's local finger along.
2139 _task->move_finger_to(addr);
2140
2141 _task->scan_object(oop(addr));
2142 // we only partially drain the local queue and global stack
2143 _task->drain_local_queue(true);
2144 _task->drain_global_stack(true);
2145
2146 // if the has_aborted flag has been raised, we need to bail out of
2147 // the iteration
2148 return !_task->has_aborted();
2149 }
2150 };
2151
2152 static ReferenceProcessor* get_cm_oop_closure_ref_processor(G1CollectedHeap* g1h) {
2153 ReferenceProcessor* result = g1h->ref_processor_cm();
2154 assert(result != NULL, "CM reference processor should not be NULL");
2155 return result;
2156 }
2157
2158 G1CMOopClosure::G1CMOopClosure(G1CollectedHeap* g1h,
2159 G1ConcurrentMark* cm,
2160 G1CMTask* task)
2161 : MetadataAwareOopClosure(get_cm_oop_closure_ref_processor(g1h)),
2162 _g1h(g1h), _cm(cm), _task(task)
2163 { }
2164
2165 void G1CMTask::setup_for_region(HeapRegion* hr) {
2166 assert(hr != NULL,
2167 "claim_region() should have filtered out NULL regions");
2168 _curr_region = hr;
2169 _finger = hr->bottom();
2170 update_region_limit();
2171 }
2172
2173 void G1CMTask::update_region_limit() {
2174 HeapRegion* hr = _curr_region;
2175 HeapWord* bottom = hr->bottom();
2176 HeapWord* limit = hr->next_top_at_mark_start();
2177
2178 if (limit == bottom) {
2179 // The region was collected underneath our feet.
2180 // We set the finger to bottom to ensure that the bitmap
2181 // iteration that will follow this will not do anything.
2182 // (this is not a condition that holds when we set the region up,
2183 // as the region is not supposed to be empty in the first place)
2184 _finger = bottom;
2185 } else if (limit >= _region_limit) {
2186 assert(limit >= _finger, "peace of mind");
2187 } else {
2188 assert(limit < _region_limit, "only way to get here");
2189 // This can happen under some pretty unusual circumstances. An
2190 // evacuation pause empties the region underneath our feet (NTAMS
2191 // at bottom). We then do some allocation in the region (NTAMS
2192 // stays at bottom), followed by the region being used as a GC
2193 // alloc region (NTAMS will move to top() and the objects
2194 // originally below it will be grayed). All objects now marked in
2195 // the region are explicitly grayed, if below the global finger,
2196 // and we do not need in fact to scan anything else. So, we simply
2197 // set _finger to be limit to ensure that the bitmap iteration
2198 // doesn't do anything.
2199 _finger = limit;
2200 }
2201
2202 _region_limit = limit;
2203 }
2204
2205 void G1CMTask::giveup_current_region() {
2206 assert(_curr_region != NULL, "invariant");
2207 clear_region_fields();
2208 }
2209
2210 void G1CMTask::clear_region_fields() {
2211 // Values for these three fields that indicate that we're not
2212 // holding on to a region.
2213 _curr_region = NULL;
2214 _finger = NULL;
2215 _region_limit = NULL;
2216 }
2217
2218 void G1CMTask::set_cm_oop_closure(G1CMOopClosure* cm_oop_closure) {
2219 if (cm_oop_closure == NULL) {
2220 assert(_cm_oop_closure != NULL, "invariant");
2221 } else {
2222 assert(_cm_oop_closure == NULL, "invariant");
2223 }
2224 _cm_oop_closure = cm_oop_closure;
2225 }
2226
2227 void G1CMTask::reset(G1CMBitMap* nextMarkBitMap) {
2228 guarantee(nextMarkBitMap != NULL, "invariant");
2229 _nextMarkBitMap = nextMarkBitMap;
2230 clear_region_fields();
2231
2232 _calls = 0;
2233 _elapsed_time_ms = 0.0;
2234 _termination_time_ms = 0.0;
2235 _termination_start_time_ms = 0.0;
2236 }
2237
2238 bool G1CMTask::should_exit_termination() {
2239 regular_clock_call();
2240 // This is called when we are in the termination protocol. We should
2241 // quit if, for some reason, this task wants to abort or the global
2242 // stack is not empty (this means that we can get work from it).
2243 return !_cm->mark_stack_empty() || has_aborted();
2244 }
2245
2246 void G1CMTask::reached_limit() {
2247 assert(_words_scanned >= _words_scanned_limit ||
2248 _refs_reached >= _refs_reached_limit ,
2249 "shouldn't have been called otherwise");
2250 regular_clock_call();
2251 }
2252
2253 void G1CMTask::regular_clock_call() {
2254 if (has_aborted()) return;
2255
2256 // First, we need to recalculate the words scanned and refs reached
2257 // limits for the next clock call.
2258 recalculate_limits();
2259
2260 // During the regular clock call we do the following
2261
2262 // (1) If an overflow has been flagged, then we abort.
2263 if (_cm->has_overflown()) {
2264 set_has_aborted();
2265 return;
2266 }
2267
2268 // If we are not concurrent (i.e. we're doing remark) we don't need
2269 // to check anything else. The other steps are only needed during
2270 // the concurrent marking phase.
2271 if (!concurrent()) return;
2272
2273 // (2) If marking has been aborted for Full GC, then we also abort.
2274 if (_cm->has_aborted()) {
2275 set_has_aborted();
2276 return;
2277 }
2278
2279 double curr_time_ms = os::elapsedVTime() * 1000.0;
2280
2281 // (4) We check whether we should yield. If we have to, then we abort.
2282 if (SuspendibleThreadSet::should_yield()) {
2283 // We should yield. To do this we abort the task. The caller is
2284 // responsible for yielding.
2285 set_has_aborted();
2286 return;
2287 }
2288
2289 // (5) We check whether we've reached our time quota. If we have,
2290 // then we abort.
2291 double elapsed_time_ms = curr_time_ms - _start_time_ms;
2292 if (elapsed_time_ms > _time_target_ms) {
2293 set_has_aborted();
2294 _has_timed_out = true;
2295 return;
2296 }
2297
2298 // (6) Finally, we check whether there are enough completed STAB
2299 // buffers available for processing. If there are, we abort.
2300 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
2301 if (!_draining_satb_buffers && satb_mq_set.process_completed_buffers()) {
2302 // we do need to process SATB buffers, we'll abort and restart
2303 // the marking task to do so
2304 set_has_aborted();
2305 return;
2306 }
2307 }
2308
2309 void G1CMTask::recalculate_limits() {
2310 _real_words_scanned_limit = _words_scanned + words_scanned_period;
2311 _words_scanned_limit = _real_words_scanned_limit;
2312
2313 _real_refs_reached_limit = _refs_reached + refs_reached_period;
2314 _refs_reached_limit = _real_refs_reached_limit;
2315 }
2316
2317 void G1CMTask::decrease_limits() {
2318 // This is called when we believe that we're going to do an infrequent
2319 // operation which will increase the per byte scanned cost (i.e. move
2320 // entries to/from the global stack). It basically tries to decrease the
2321 // scanning limit so that the clock is called earlier.
2322
2323 _words_scanned_limit = _real_words_scanned_limit -
2324 3 * words_scanned_period / 4;
2325 _refs_reached_limit = _real_refs_reached_limit -
2326 3 * refs_reached_period / 4;
2327 }
2328
2329 void G1CMTask::move_entries_to_global_stack() {
2330 // local array where we'll store the entries that will be popped
2331 // from the local queue
2332 oop buffer[global_stack_transfer_size];
2333
2334 int n = 0;
2335 oop obj;
2336 while (n < global_stack_transfer_size && _task_queue->pop_local(obj)) {
2337 buffer[n] = obj;
2338 ++n;
2339 }
2340
2341 if (n > 0) {
2342 // we popped at least one entry from the local queue
2343
2344 if (!_cm->mark_stack_push(buffer, n)) {
2345 set_has_aborted();
2346 }
2347 }
2348
2349 // this operation was quite expensive, so decrease the limits
2350 decrease_limits();
2351 }
2352
2353 void G1CMTask::get_entries_from_global_stack() {
2354 // local array where we'll store the entries that will be popped
2355 // from the global stack.
2356 oop buffer[global_stack_transfer_size];
2357 int n;
2358 _cm->mark_stack_pop(buffer, global_stack_transfer_size, &n);
2359 assert(n <= global_stack_transfer_size,
2360 "we should not pop more than the given limit");
2361 if (n > 0) {
2362 // yes, we did actually pop at least one entry
2363 for (int i = 0; i < n; ++i) {
2364 bool success = _task_queue->push(buffer[i]);
2365 // We only call this when the local queue is empty or under a
2366 // given target limit. So, we do not expect this push to fail.
2367 assert(success, "invariant");
2368 }
2369 }
2370
2371 // this operation was quite expensive, so decrease the limits
2372 decrease_limits();
2373 }
2374
2375 void G1CMTask::drain_local_queue(bool partially) {
2376 if (has_aborted()) return;
2377
2378 // Decide what the target size is, depending whether we're going to
2379 // drain it partially (so that other tasks can steal if they run out
2380 // of things to do) or totally (at the very end).
2381 size_t target_size;
2382 if (partially) {
2383 target_size = MIN2((size_t)_task_queue->max_elems()/3, GCDrainStackTargetSize);
2384 } else {
2385 target_size = 0;
2386 }
2387
2388 if (_task_queue->size() > target_size) {
2389 oop obj;
2390 bool ret = _task_queue->pop_local(obj);
2391 while (ret) {
2392 assert(_g1h->is_in_g1_reserved((HeapWord*) obj), "invariant" );
2393 assert(!_g1h->is_on_master_free_list(
2394 _g1h->heap_region_containing((HeapWord*) obj)), "invariant");
2395
2396 scan_object(obj);
2397
2398 if (_task_queue->size() <= target_size || has_aborted()) {
2399 ret = false;
2400 } else {
2401 ret = _task_queue->pop_local(obj);
2402 }
2403 }
2404 }
2405 }
2406
2407 void G1CMTask::drain_global_stack(bool partially) {
2408 if (has_aborted()) return;
2409
2410 // We have a policy to drain the local queue before we attempt to
2411 // drain the global stack.
2412 assert(partially || _task_queue->size() == 0, "invariant");
2413
2414 // Decide what the target size is, depending whether we're going to
2415 // drain it partially (so that other tasks can steal if they run out
2416 // of things to do) or totally (at the very end). Notice that,
2417 // because we move entries from the global stack in chunks or
2418 // because another task might be doing the same, we might in fact
2419 // drop below the target. But, this is not a problem.
2420 size_t target_size;
2421 if (partially) {
2422 target_size = _cm->partial_mark_stack_size_target();
2423 } else {
2424 target_size = 0;
2425 }
2426
2427 if (_cm->mark_stack_size() > target_size) {
2428 while (!has_aborted() && _cm->mark_stack_size() > target_size) {
2429 get_entries_from_global_stack();
2430 drain_local_queue(partially);
2431 }
2432 }
2433 }
2434
2435 // SATB Queue has several assumptions on whether to call the par or
2436 // non-par versions of the methods. this is why some of the code is
2437 // replicated. We should really get rid of the single-threaded version
2438 // of the code to simplify things.
2439 void G1CMTask::drain_satb_buffers() {
2440 if (has_aborted()) return;
2441
2442 // We set this so that the regular clock knows that we're in the
2443 // middle of draining buffers and doesn't set the abort flag when it
2444 // notices that SATB buffers are available for draining. It'd be
2445 // very counter productive if it did that. :-)
2446 _draining_satb_buffers = true;
2447
2448 G1CMSATBBufferClosure satb_cl(this, _g1h);
2449 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
2450
2451 // This keeps claiming and applying the closure to completed buffers
2452 // until we run out of buffers or we need to abort.
2453 while (!has_aborted() &&
2454 satb_mq_set.apply_closure_to_completed_buffer(&satb_cl)) {
2455 regular_clock_call();
2456 }
2457
2458 _draining_satb_buffers = false;
2459
2460 assert(has_aborted() ||
2461 concurrent() ||
2462 satb_mq_set.completed_buffers_num() == 0, "invariant");
2463
2464 // again, this was a potentially expensive operation, decrease the
2465 // limits to get the regular clock call early
2466 decrease_limits();
2467 }
2468
2469 void G1CMTask::print_stats() {
2470 log_debug(gc, stats)("Marking Stats, task = %u, calls = %d",
2471 _worker_id, _calls);
2472 log_debug(gc, stats)(" Elapsed time = %1.2lfms, Termination time = %1.2lfms",
2473 _elapsed_time_ms, _termination_time_ms);
2474 log_debug(gc, stats)(" Step Times (cum): num = %d, avg = %1.2lfms, sd = %1.2lfms",
2475 _step_times_ms.num(), _step_times_ms.avg(),
2476 _step_times_ms.sd());
2477 log_debug(gc, stats)(" max = %1.2lfms, total = %1.2lfms",
2478 _step_times_ms.maximum(), _step_times_ms.sum());
2479 }
2480
2481 bool G1ConcurrentMark::try_stealing(uint worker_id, int* hash_seed, oop& obj) {
2482 return _task_queues->steal(worker_id, hash_seed, obj);
2483 }
2484
2485 /*****************************************************************************
2486
2487 The do_marking_step(time_target_ms, ...) method is the building
2488 block of the parallel marking framework. It can be called in parallel
2489 with other invocations of do_marking_step() on different tasks
2490 (but only one per task, obviously) and concurrently with the
2491 mutator threads, or during remark, hence it eliminates the need
2492 for two versions of the code. When called during remark, it will
2493 pick up from where the task left off during the concurrent marking
2494 phase. Interestingly, tasks are also claimable during evacuation
2495 pauses too, since do_marking_step() ensures that it aborts before
2496 it needs to yield.
2497
2498 The data structures that it uses to do marking work are the
2499 following:
2500
2501 (1) Marking Bitmap. If there are gray objects that appear only
2502 on the bitmap (this happens either when dealing with an overflow
2503 or when the initial marking phase has simply marked the roots
2504 and didn't push them on the stack), then tasks claim heap
2505 regions whose bitmap they then scan to find gray objects. A
2506 global finger indicates where the end of the last claimed region
2507 is. A local finger indicates how far into the region a task has
2508 scanned. The two fingers are used to determine how to gray an
2509 object (i.e. whether simply marking it is OK, as it will be
2510 visited by a task in the future, or whether it needs to be also
2511 pushed on a stack).
2512
2513 (2) Local Queue. The local queue of the task which is accessed
2514 reasonably efficiently by the task. Other tasks can steal from
2515 it when they run out of work. Throughout the marking phase, a
2516 task attempts to keep its local queue short but not totally
2517 empty, so that entries are available for stealing by other
2518 tasks. Only when there is no more work, a task will totally
2519 drain its local queue.
2520
2521 (3) Global Mark Stack. This handles local queue overflow. During
2522 marking only sets of entries are moved between it and the local
2523 queues, as access to it requires a mutex and more fine-grain
2524 interaction with it which might cause contention. If it
2525 overflows, then the marking phase should restart and iterate
2526 over the bitmap to identify gray objects. Throughout the marking
2527 phase, tasks attempt to keep the global mark stack at a small
2528 length but not totally empty, so that entries are available for
2529 popping by other tasks. Only when there is no more work, tasks
2530 will totally drain the global mark stack.
2531
2532 (4) SATB Buffer Queue. This is where completed SATB buffers are
2533 made available. Buffers are regularly removed from this queue
2534 and scanned for roots, so that the queue doesn't get too
2535 long. During remark, all completed buffers are processed, as
2536 well as the filled in parts of any uncompleted buffers.
2537
2538 The do_marking_step() method tries to abort when the time target
2539 has been reached. There are a few other cases when the
2540 do_marking_step() method also aborts:
2541
2542 (1) When the marking phase has been aborted (after a Full GC).
2543
2544 (2) When a global overflow (on the global stack) has been
2545 triggered. Before the task aborts, it will actually sync up with
2546 the other tasks to ensure that all the marking data structures
2547 (local queues, stacks, fingers etc.) are re-initialized so that
2548 when do_marking_step() completes, the marking phase can
2549 immediately restart.
2550
2551 (3) When enough completed SATB buffers are available. The
2552 do_marking_step() method only tries to drain SATB buffers right
2553 at the beginning. So, if enough buffers are available, the
2554 marking step aborts and the SATB buffers are processed at
2555 the beginning of the next invocation.
2556
2557 (4) To yield. when we have to yield then we abort and yield
2558 right at the end of do_marking_step(). This saves us from a lot
2559 of hassle as, by yielding we might allow a Full GC. If this
2560 happens then objects will be compacted underneath our feet, the
2561 heap might shrink, etc. We save checking for this by just
2562 aborting and doing the yield right at the end.
2563
2564 From the above it follows that the do_marking_step() method should
2565 be called in a loop (or, otherwise, regularly) until it completes.
2566
2567 If a marking step completes without its has_aborted() flag being
2568 true, it means it has completed the current marking phase (and
2569 also all other marking tasks have done so and have all synced up).
2570
2571 A method called regular_clock_call() is invoked "regularly" (in
2572 sub ms intervals) throughout marking. It is this clock method that
2573 checks all the abort conditions which were mentioned above and
2574 decides when the task should abort. A work-based scheme is used to
2575 trigger this clock method: when the number of object words the
2576 marking phase has scanned or the number of references the marking
2577 phase has visited reach a given limit. Additional invocations to
2578 the method clock have been planted in a few other strategic places
2579 too. The initial reason for the clock method was to avoid calling
2580 vtime too regularly, as it is quite expensive. So, once it was in
2581 place, it was natural to piggy-back all the other conditions on it
2582 too and not constantly check them throughout the code.
2583
2584 If do_termination is true then do_marking_step will enter its
2585 termination protocol.
2586
2587 The value of is_serial must be true when do_marking_step is being
2588 called serially (i.e. by the VMThread) and do_marking_step should
2589 skip any synchronization in the termination and overflow code.
2590 Examples include the serial remark code and the serial reference
2591 processing closures.
2592
2593 The value of is_serial must be false when do_marking_step is
2594 being called by any of the worker threads in a work gang.
2595 Examples include the concurrent marking code (CMMarkingTask),
2596 the MT remark code, and the MT reference processing closures.
2597
2598 *****************************************************************************/
2599
2600 void G1CMTask::do_marking_step(double time_target_ms,
2601 bool do_termination,
2602 bool is_serial) {
2603 assert(time_target_ms >= 1.0, "minimum granularity is 1ms");
2604 assert(concurrent() == _cm->concurrent(), "they should be the same");
2605
2606 G1Policy* g1_policy = _g1h->g1_policy();
2607 assert(_task_queues != NULL, "invariant");
2608 assert(_task_queue != NULL, "invariant");
2609 assert(_task_queues->queue(_worker_id) == _task_queue, "invariant");
2610
2611 assert(!_claimed,
2612 "only one thread should claim this task at any one time");
2613
2614 // OK, this doesn't safeguard again all possible scenarios, as it is
2615 // possible for two threads to set the _claimed flag at the same
2616 // time. But it is only for debugging purposes anyway and it will
2617 // catch most problems.
2618 _claimed = true;
2619
2620 _start_time_ms = os::elapsedVTime() * 1000.0;
2621
2622 // If do_stealing is true then do_marking_step will attempt to
2623 // steal work from the other G1CMTasks. It only makes sense to
2624 // enable stealing when the termination protocol is enabled
2625 // and do_marking_step() is not being called serially.
2626 bool do_stealing = do_termination && !is_serial;
2627
2628 double diff_prediction_ms = _g1h->g1_policy()->predictor().get_new_prediction(&_marking_step_diffs_ms);
2629 _time_target_ms = time_target_ms - diff_prediction_ms;
2630
2631 // set up the variables that are used in the work-based scheme to
2632 // call the regular clock method
2633 _words_scanned = 0;
2634 _refs_reached = 0;
2635 recalculate_limits();
2636
2637 // clear all flags
2638 clear_has_aborted();
2639 _has_timed_out = false;
2640 _draining_satb_buffers = false;
2641
2642 ++_calls;
2643
2644 // Set up the bitmap and oop closures. Anything that uses them is
2645 // eventually called from this method, so it is OK to allocate these
2646 // statically.
2647 G1CMBitMapClosure bitmap_closure(this, _cm, _nextMarkBitMap);
2648 G1CMOopClosure cm_oop_closure(_g1h, _cm, this);
2649 set_cm_oop_closure(&cm_oop_closure);
2650
2651 if (_cm->has_overflown()) {
2652 // This can happen if the mark stack overflows during a GC pause
2653 // and this task, after a yield point, restarts. We have to abort
2654 // as we need to get into the overflow protocol which happens
2655 // right at the end of this task.
2656 set_has_aborted();
2657 }
2658
2659 // First drain any available SATB buffers. After this, we will not
2660 // look at SATB buffers before the next invocation of this method.
2661 // If enough completed SATB buffers are queued up, the regular clock
2662 // will abort this task so that it restarts.
2663 drain_satb_buffers();
2664 // ...then partially drain the local queue and the global stack
2665 drain_local_queue(true);
2666 drain_global_stack(true);
2667
2668 do {
2669 if (!has_aborted() && _curr_region != NULL) {
2670 // This means that we're already holding on to a region.
2671 assert(_finger != NULL, "if region is not NULL, then the finger "
2672 "should not be NULL either");
2673
2674 // We might have restarted this task after an evacuation pause
2675 // which might have evacuated the region we're holding on to
2676 // underneath our feet. Let's read its limit again to make sure
2677 // that we do not iterate over a region of the heap that
2678 // contains garbage (update_region_limit() will also move
2679 // _finger to the start of the region if it is found empty).
2680 update_region_limit();
2681 // We will start from _finger not from the start of the region,
2682 // as we might be restarting this task after aborting half-way
2683 // through scanning this region. In this case, _finger points to
2684 // the address where we last found a marked object. If this is a
2685 // fresh region, _finger points to start().
2686 MemRegion mr = MemRegion(_finger, _region_limit);
2687
2688 assert(!_curr_region->is_humongous() || mr.start() == _curr_region->bottom(),
2689 "humongous regions should go around loop once only");
2690
2691 // Some special cases:
2692 // If the memory region is empty, we can just give up the region.
2693 // If the current region is humongous then we only need to check
2694 // the bitmap for the bit associated with the start of the object,
2695 // scan the object if it's live, and give up the region.
2696 // Otherwise, let's iterate over the bitmap of the part of the region
2697 // that is left.
2698 // If the iteration is successful, give up the region.
2699 if (mr.is_empty()) {
2700 giveup_current_region();
2701 regular_clock_call();
2702 } else if (_curr_region->is_humongous() && mr.start() == _curr_region->bottom()) {
2703 if (_nextMarkBitMap->isMarked(mr.start())) {
2704 // The object is marked - apply the closure
2705 BitMap::idx_t offset = _nextMarkBitMap->heapWordToOffset(mr.start());
2706 bitmap_closure.do_bit(offset);
2707 }
2708 // Even if this task aborted while scanning the humongous object
2709 // we can (and should) give up the current region.
2710 giveup_current_region();
2711 regular_clock_call();
2712 } else if (_nextMarkBitMap->iterate(&bitmap_closure, mr)) {
2713 giveup_current_region();
2714 regular_clock_call();
2715 } else {
2716 assert(has_aborted(), "currently the only way to do so");
2717 // The only way to abort the bitmap iteration is to return
2718 // false from the do_bit() method. However, inside the
2719 // do_bit() method we move the _finger to point to the
2720 // object currently being looked at. So, if we bail out, we
2721 // have definitely set _finger to something non-null.
2722 assert(_finger != NULL, "invariant");
2723
2724 // Region iteration was actually aborted. So now _finger
2725 // points to the address of the object we last scanned. If we
2726 // leave it there, when we restart this task, we will rescan
2727 // the object. It is easy to avoid this. We move the finger by
2728 // enough to point to the next possible object header (the
2729 // bitmap knows by how much we need to move it as it knows its
2730 // granularity).
2731 assert(_finger < _region_limit, "invariant");
2732 HeapWord* new_finger = _nextMarkBitMap->nextObject(_finger);
2733 // Check if bitmap iteration was aborted while scanning the last object
2734 if (new_finger >= _region_limit) {
2735 giveup_current_region();
2736 } else {
2737 move_finger_to(new_finger);
2738 }
2739 }
2740 }
2741 // At this point we have either completed iterating over the
2742 // region we were holding on to, or we have aborted.
2743
2744 // We then partially drain the local queue and the global stack.
2745 // (Do we really need this?)
2746 drain_local_queue(true);
2747 drain_global_stack(true);
2748
2749 // Read the note on the claim_region() method on why it might
2750 // return NULL with potentially more regions available for
2751 // claiming and why we have to check out_of_regions() to determine
2752 // whether we're done or not.
2753 while (!has_aborted() && _curr_region == NULL && !_cm->out_of_regions()) {
2754 // We are going to try to claim a new region. We should have
2755 // given up on the previous one.
2756 // Separated the asserts so that we know which one fires.
2757 assert(_curr_region == NULL, "invariant");
2758 assert(_finger == NULL, "invariant");
2759 assert(_region_limit == NULL, "invariant");
2760 HeapRegion* claimed_region = _cm->claim_region(_worker_id);
2761 if (claimed_region != NULL) {
2762 // Yes, we managed to claim one
2763 setup_for_region(claimed_region);
2764 assert(_curr_region == claimed_region, "invariant");
2765 }
2766 // It is important to call the regular clock here. It might take
2767 // a while to claim a region if, for example, we hit a large
2768 // block of empty regions. So we need to call the regular clock
2769 // method once round the loop to make sure it's called
2770 // frequently enough.
2771 regular_clock_call();
2772 }
2773
2774 if (!has_aborted() && _curr_region == NULL) {
2775 assert(_cm->out_of_regions(),
2776 "at this point we should be out of regions");
2777 }
2778 } while ( _curr_region != NULL && !has_aborted());
2779
2780 if (!has_aborted()) {
2781 // We cannot check whether the global stack is empty, since other
2782 // tasks might be pushing objects to it concurrently.
2783 assert(_cm->out_of_regions(),
2784 "at this point we should be out of regions");
2785 // Try to reduce the number of available SATB buffers so that
2786 // remark has less work to do.
2787 drain_satb_buffers();
2788 }
2789
2790 // Since we've done everything else, we can now totally drain the
2791 // local queue and global stack.
2792 drain_local_queue(false);
2793 drain_global_stack(false);
2794
2795 // Attempt at work stealing from other task's queues.
2796 if (do_stealing && !has_aborted()) {
2797 // We have not aborted. This means that we have finished all that
2798 // we could. Let's try to do some stealing...
2799
2800 // We cannot check whether the global stack is empty, since other
2801 // tasks might be pushing objects to it concurrently.
2802 assert(_cm->out_of_regions() && _task_queue->size() == 0,
2803 "only way to reach here");
2804 while (!has_aborted()) {
2805 oop obj;
2806 if (_cm->try_stealing(_worker_id, &_hash_seed, obj)) {
2807 assert(_nextMarkBitMap->isMarked((HeapWord*) obj),
2808 "any stolen object should be marked");
2809 scan_object(obj);
2810
2811 // And since we're towards the end, let's totally drain the
2812 // local queue and global stack.
2813 drain_local_queue(false);
2814 drain_global_stack(false);
2815 } else {
2816 break;
2817 }
2818 }
2819 }
2820
2821 // We still haven't aborted. Now, let's try to get into the
2822 // termination protocol.
2823 if (do_termination && !has_aborted()) {
2824 // We cannot check whether the global stack is empty, since other
2825 // tasks might be concurrently pushing objects on it.
2826 // Separated the asserts so that we know which one fires.
2827 assert(_cm->out_of_regions(), "only way to reach here");
2828 assert(_task_queue->size() == 0, "only way to reach here");
2829 _termination_start_time_ms = os::elapsedVTime() * 1000.0;
2830
2831 // The G1CMTask class also extends the TerminatorTerminator class,
2832 // hence its should_exit_termination() method will also decide
2833 // whether to exit the termination protocol or not.
2834 bool finished = (is_serial ||
2835 _cm->terminator()->offer_termination(this));
2836 double termination_end_time_ms = os::elapsedVTime() * 1000.0;
2837 _termination_time_ms +=
2838 termination_end_time_ms - _termination_start_time_ms;
2839
2840 if (finished) {
2841 // We're all done.
2842
2843 if (_worker_id == 0) {
2844 // let's allow task 0 to do this
2845 if (concurrent()) {
2846 assert(_cm->concurrent_marking_in_progress(), "invariant");
2847 // we need to set this to false before the next
2848 // safepoint. This way we ensure that the marking phase
2849 // doesn't observe any more heap expansions.
2850 _cm->clear_concurrent_marking_in_progress();
2851 }
2852 }
2853
2854 // We can now guarantee that the global stack is empty, since
2855 // all other tasks have finished. We separated the guarantees so
2856 // that, if a condition is false, we can immediately find out
2857 // which one.
2858 guarantee(_cm->out_of_regions(), "only way to reach here");
2859 guarantee(_cm->mark_stack_empty(), "only way to reach here");
2860 guarantee(_task_queue->size() == 0, "only way to reach here");
2861 guarantee(!_cm->has_overflown(), "only way to reach here");
2862 guarantee(!_cm->mark_stack_overflow(), "only way to reach here");
2863 } else {
2864 // Apparently there's more work to do. Let's abort this task. It
2865 // will restart it and we can hopefully find more things to do.
2866 set_has_aborted();
2867 }
2868 }
2869
2870 // Mainly for debugging purposes to make sure that a pointer to the
2871 // closure which was statically allocated in this frame doesn't
2872 // escape it by accident.
2873 set_cm_oop_closure(NULL);
2874 double end_time_ms = os::elapsedVTime() * 1000.0;
2875 double elapsed_time_ms = end_time_ms - _start_time_ms;
2876 // Update the step history.
2877 _step_times_ms.add(elapsed_time_ms);
2878
2879 if (has_aborted()) {
2880 // The task was aborted for some reason.
2881 if (_has_timed_out) {
2882 double diff_ms = elapsed_time_ms - _time_target_ms;
2883 // Keep statistics of how well we did with respect to hitting
2884 // our target only if we actually timed out (if we aborted for
2885 // other reasons, then the results might get skewed).
2886 _marking_step_diffs_ms.add(diff_ms);
2887 }
2888
2889 if (_cm->has_overflown()) {
2890 // This is the interesting one. We aborted because a global
2891 // overflow was raised. This means we have to restart the
2892 // marking phase and start iterating over regions. However, in
2893 // order to do this we have to make sure that all tasks stop
2894 // what they are doing and re-initialize in a safe manner. We
2895 // will achieve this with the use of two barrier sync points.
2896
2897 if (!is_serial) {
2898 // We only need to enter the sync barrier if being called
2899 // from a parallel context
2900 _cm->enter_first_sync_barrier(_worker_id);
2901
2902 // When we exit this sync barrier we know that all tasks have
2903 // stopped doing marking work. So, it's now safe to
2904 // re-initialize our data structures. At the end of this method,
2905 // task 0 will clear the global data structures.
2906 }
2907
2908 // We clear the local state of this task...
2909 clear_region_fields();
2910
2911 if (!is_serial) {
2912 // ...and enter the second barrier.
2913 _cm->enter_second_sync_barrier(_worker_id);
2914 }
2915 // At this point, if we're during the concurrent phase of
2916 // marking, everything has been re-initialized and we're
2917 // ready to restart.
2918 }
2919 }
2920
2921 _claimed = false;
2922 }
2923
2924 G1CMTask::G1CMTask(uint worker_id,
2925 G1ConcurrentMark* cm,
2926 G1CMTaskQueue* task_queue,
2927 G1CMTaskQueueSet* task_queues)
2928 : _g1h(G1CollectedHeap::heap()),
2929 _worker_id(worker_id), _cm(cm),
2930 _claimed(false),
2931 _nextMarkBitMap(NULL), _hash_seed(17),
2932 _task_queue(task_queue),
2933 _task_queues(task_queues),
2934 _cm_oop_closure(NULL) {
2935 guarantee(task_queue != NULL, "invariant");
2936 guarantee(task_queues != NULL, "invariant");
2937
2938 _marking_step_diffs_ms.add(0.5);
2939 }
2940
2941 // These are formatting macros that are used below to ensure
2942 // consistent formatting. The *_H_* versions are used to format the
2943 // header for a particular value and they should be kept consistent
2944 // with the corresponding macro. Also note that most of the macros add
2945 // the necessary white space (as a prefix) which makes them a bit
2946 // easier to compose.
2947
2948 // All the output lines are prefixed with this string to be able to
2949 // identify them easily in a large log file.
2950 #define G1PPRL_LINE_PREFIX "###"
2951
2952 #define G1PPRL_ADDR_BASE_FORMAT " " PTR_FORMAT "-" PTR_FORMAT
2953 #ifdef _LP64
2954 #define G1PPRL_ADDR_BASE_H_FORMAT " %37s"
2955 #else // _LP64
2956 #define G1PPRL_ADDR_BASE_H_FORMAT " %21s"
2957 #endif // _LP64
2958
2959 // For per-region info
2960 #define G1PPRL_TYPE_FORMAT " %-4s"
2961 #define G1PPRL_TYPE_H_FORMAT " %4s"
2962 #define G1PPRL_BYTE_FORMAT " " SIZE_FORMAT_W(9)
2963 #define G1PPRL_BYTE_H_FORMAT " %9s"
2964 #define G1PPRL_DOUBLE_FORMAT " %14.1f"
2965 #define G1PPRL_DOUBLE_H_FORMAT " %14s"
2966
2967 // For summary info
2968 #define G1PPRL_SUM_ADDR_FORMAT(tag) " " tag ":" G1PPRL_ADDR_BASE_FORMAT
2969 #define G1PPRL_SUM_BYTE_FORMAT(tag) " " tag ": " SIZE_FORMAT
2970 #define G1PPRL_SUM_MB_FORMAT(tag) " " tag ": %1.2f MB"
2971 #define G1PPRL_SUM_MB_PERC_FORMAT(tag) G1PPRL_SUM_MB_FORMAT(tag) " / %1.2f %%"
2972
2973 G1PrintRegionLivenessInfoClosure::
2974 G1PrintRegionLivenessInfoClosure(const char* phase_name)
2975 : _total_used_bytes(0), _total_capacity_bytes(0),
2976 _total_prev_live_bytes(0), _total_next_live_bytes(0),
2977 _total_remset_bytes(0), _total_strong_code_roots_bytes(0) {
2978 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2979 MemRegion g1_reserved = g1h->g1_reserved();
2980 double now = os::elapsedTime();
2981
2982 // Print the header of the output.
2983 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX" PHASE %s @ %1.3f", phase_name, now);
2984 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX" HEAP"
2985 G1PPRL_SUM_ADDR_FORMAT("reserved")
2986 G1PPRL_SUM_BYTE_FORMAT("region-size"),
2987 p2i(g1_reserved.start()), p2i(g1_reserved.end()),
2988 HeapRegion::GrainBytes);
2989 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX);
2990 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX
2991 G1PPRL_TYPE_H_FORMAT
2992 G1PPRL_ADDR_BASE_H_FORMAT
2993 G1PPRL_BYTE_H_FORMAT
2994 G1PPRL_BYTE_H_FORMAT
2995 G1PPRL_BYTE_H_FORMAT
2996 G1PPRL_DOUBLE_H_FORMAT
2997 G1PPRL_BYTE_H_FORMAT
2998 G1PPRL_BYTE_H_FORMAT,
2999 "type", "address-range",
3000 "used", "prev-live", "next-live", "gc-eff",
3001 "remset", "code-roots");
3002 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX
3003 G1PPRL_TYPE_H_FORMAT
3004 G1PPRL_ADDR_BASE_H_FORMAT
3005 G1PPRL_BYTE_H_FORMAT
3006 G1PPRL_BYTE_H_FORMAT
3007 G1PPRL_BYTE_H_FORMAT
3008 G1PPRL_DOUBLE_H_FORMAT
3009 G1PPRL_BYTE_H_FORMAT
3010 G1PPRL_BYTE_H_FORMAT,
3011 "", "",
3012 "(bytes)", "(bytes)", "(bytes)", "(bytes/ms)",
3013 "(bytes)", "(bytes)");
3014 }
3015
3016 bool G1PrintRegionLivenessInfoClosure::doHeapRegion(HeapRegion* r) {
3017 const char* type = r->get_type_str();
3018 HeapWord* bottom = r->bottom();
3019 HeapWord* end = r->end();
3020 size_t capacity_bytes = r->capacity();
3021 size_t used_bytes = r->used();
3022 size_t prev_live_bytes = r->live_bytes();
3023 size_t next_live_bytes = r->next_live_bytes();
3024 double gc_eff = r->gc_efficiency();
3025 size_t remset_bytes = r->rem_set()->mem_size();
3026 size_t strong_code_roots_bytes = r->rem_set()->strong_code_roots_mem_size();
3027
3028 _total_used_bytes += used_bytes;
3029 _total_capacity_bytes += capacity_bytes;
3030 _total_prev_live_bytes += prev_live_bytes;
3031 _total_next_live_bytes += next_live_bytes;
3032 _total_remset_bytes += remset_bytes;
3033 _total_strong_code_roots_bytes += strong_code_roots_bytes;
3034
3035 // Print a line for this particular region.
3036 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX
3037 G1PPRL_TYPE_FORMAT
3038 G1PPRL_ADDR_BASE_FORMAT
3039 G1PPRL_BYTE_FORMAT
3040 G1PPRL_BYTE_FORMAT
3041 G1PPRL_BYTE_FORMAT
3042 G1PPRL_DOUBLE_FORMAT
3043 G1PPRL_BYTE_FORMAT
3044 G1PPRL_BYTE_FORMAT,
3045 type, p2i(bottom), p2i(end),
3046 used_bytes, prev_live_bytes, next_live_bytes, gc_eff,
3047 remset_bytes, strong_code_roots_bytes);
3048
3049 return false;
3050 }
3051
3052 G1PrintRegionLivenessInfoClosure::~G1PrintRegionLivenessInfoClosure() {
3053 // add static memory usages to remembered set sizes
3054 _total_remset_bytes += HeapRegionRemSet::fl_mem_size() + HeapRegionRemSet::static_mem_size();
3055 // Print the footer of the output.
3056 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX);
3057 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX
3058 " SUMMARY"
3059 G1PPRL_SUM_MB_FORMAT("capacity")
3060 G1PPRL_SUM_MB_PERC_FORMAT("used")
3061 G1PPRL_SUM_MB_PERC_FORMAT("prev-live")
3062 G1PPRL_SUM_MB_PERC_FORMAT("next-live")
3063 G1PPRL_SUM_MB_FORMAT("remset")
3064 G1PPRL_SUM_MB_FORMAT("code-roots"),
3065 bytes_to_mb(_total_capacity_bytes),
3066 bytes_to_mb(_total_used_bytes),
3067 perc(_total_used_bytes, _total_capacity_bytes),
3068 bytes_to_mb(_total_prev_live_bytes),
3069 perc(_total_prev_live_bytes, _total_capacity_bytes),
3070 bytes_to_mb(_total_next_live_bytes),
3071 perc(_total_next_live_bytes, _total_capacity_bytes),
3072 bytes_to_mb(_total_remset_bytes),
3073 bytes_to_mb(_total_strong_code_roots_bytes));
3074 }