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
61 // Concurrent marking bit map wrapper
62
63 G1CMBitMapRO::G1CMBitMapRO(int shifter) :
64 _bm(),
65 _shifter(shifter) {
66 _bmStartWord = 0;
67 _bmWordSize = 0;
68 }
69
70 HeapWord* G1CMBitMapRO::getNextMarkedWordAddress(const HeapWord* addr,
71 const HeapWord* limit) const {
72 // First we must round addr *up* to a possible object boundary.
73 addr = (HeapWord*)align_size_up((intptr_t)addr,
74 HeapWordSize << _shifter);
75 size_t addrOffset = heapWordToOffset(addr);
76 assert(limit != NULL, "limit must not be NULL");
77 size_t limitOffset = heapWordToOffset(limit);
78 size_t nextOffset = _bm.get_next_one_offset(addrOffset, limitOffset);
79 HeapWord* nextAddr = offsetToHeapWord(nextOffset);
80 assert(nextAddr >= addr, "get_next_one postcondition");
81 assert(nextAddr == limit || isMarked(nextAddr),
82 "get_next_one postcondition");
83 return nextAddr;
84 }
85
86 #ifndef PRODUCT
87 bool G1CMBitMapRO::covers(MemRegion heap_rs) const {
88 // assert(_bm.map() == _virtual_space.low(), "map inconsistency");
89 assert(((size_t)_bm.size() * ((size_t)1 << _shifter)) == _bmWordSize,
90 "size inconsistency");
91 return _bmStartWord == (HeapWord*)(heap_rs.start()) &&
92 _bmWordSize == heap_rs.word_size();
93 }
94 #endif
95
96 void G1CMBitMapRO::print_on_error(outputStream* st, const char* prefix) const {
97 _bm.print_on_error(st, prefix);
98 }
99
100 size_t G1CMBitMap::compute_size(size_t heap_size) {
101 return ReservedSpace::allocation_align_size_up(heap_size / mark_distance());
102 }
103
104 size_t G1CMBitMap::mark_distance() {
105 return MinObjAlignmentInBytes * BitsPerByte;
106 }
107
108 void G1CMBitMap::initialize(MemRegion heap, G1RegionToSpaceMapper* storage) {
109 _bmStartWord = heap.start();
110 _bmWordSize = heap.word_size();
111
112 _bm.set_map((BitMap::bm_word_t*) storage->reserved().start());
113 _bm.set_size(_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 _young_list(NULL), _cm(NULL), _scan_in_progress(false),
264 _should_abort(false), _next_survivor(NULL) { }
265
266 void G1CMRootRegions::init(G1CollectedHeap* g1h, G1ConcurrentMark* cm) {
267 _young_list = g1h->young_list();
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 assert(_next_survivor == NULL, "pre-condition");
276 _next_survivor = _young_list->first_survivor_region();
277 _scan_in_progress = (_next_survivor != NULL);
278 _should_abort = false;
279 }
280
281 HeapRegion* G1CMRootRegions::claim_next() {
282 if (_should_abort) {
283 // If someone has set the should_abort flag, we return NULL to
284 // force the caller to bail out of their loop.
285 return NULL;
286 }
287
288 // Currently, only survivors can be root regions.
289 HeapRegion* res = _next_survivor;
290 if (res != NULL) {
291 MutexLockerEx x(RootRegionScan_lock, Mutex::_no_safepoint_check_flag);
292 // Read it again in case it changed while we were waiting for the lock.
293 res = _next_survivor;
294 if (res != NULL) {
295 if (res == _young_list->last_survivor_region()) {
296 // We just claimed the last survivor so store NULL to indicate
297 // that we're done.
298 _next_survivor = NULL;
299 } else {
300 _next_survivor = res->get_next_young_region();
301 }
302 } else {
303 // Someone else claimed the last survivor while we were trying
304 // to take the lock so nothing else to do.
305 }
306 }
307 assert(res == NULL || res->is_survivor(), "post-condition");
308
309 return res;
310 }
311
312 void G1CMRootRegions::notify_scan_done() {
313 MutexLockerEx x(RootRegionScan_lock, Mutex::_no_safepoint_check_flag);
314 _scan_in_progress = false;
315 RootRegionScan_lock->notify_all();
316 }
317
318 void G1CMRootRegions::cancel_scan() {
319 notify_scan_done();
320 }
321
322 void G1CMRootRegions::scan_finished() {
323 assert(scan_in_progress(), "pre-condition");
324
325 // Currently, only survivors can be root regions.
326 if (!_should_abort) {
327 assert(_next_survivor == NULL, "we should have claimed all survivors");
328 }
329 _next_survivor = NULL;
330
331 notify_scan_done();
332 }
333
334 bool G1CMRootRegions::wait_until_scan_finished() {
335 if (!scan_in_progress()) return false;
336
337 {
338 MutexLockerEx x(RootRegionScan_lock, Mutex::_no_safepoint_check_flag);
339 while (scan_in_progress()) {
340 RootRegionScan_lock->wait(Mutex::_no_safepoint_check_flag);
341 }
342 }
343 return true;
344 }
345
346 uint G1ConcurrentMark::scale_parallel_threads(uint n_par_threads) {
347 return MAX2((n_par_threads + 2) / 4, 1U);
348 }
349
350 G1ConcurrentMark::G1ConcurrentMark(G1CollectedHeap* g1h, G1RegionToSpaceMapper* prev_bitmap_storage, G1RegionToSpaceMapper* next_bitmap_storage) :
351 _g1h(g1h),
352 _markBitMap1(),
353 _markBitMap2(),
354 _parallel_marking_threads(0),
355 _max_parallel_marking_threads(0),
356 _sleep_factor(0.0),
357 _marking_task_overhead(1.0),
358 _cleanup_list("Cleanup List"),
359
360 _prevMarkBitMap(&_markBitMap1),
361 _nextMarkBitMap(&_markBitMap2),
362
363 _markStack(this),
364 // _finger set in set_non_marking_state
365
366 _max_worker_id(ParallelGCThreads),
367 // _active_tasks set in set_non_marking_state
368 // _tasks set inside the constructor
369 _task_queues(new G1CMTaskQueueSet((int) _max_worker_id)),
370 _terminator(ParallelTaskTerminator((int) _max_worker_id, _task_queues)),
371
372 _has_overflown(false),
373 _concurrent(false),
374 _has_aborted(false),
375 _restart_for_overflow(false),
376 _concurrent_marking_in_progress(false),
377 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
378 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()),
379
380 // _verbose_level set below
381
382 _init_times(),
383 _remark_times(), _remark_mark_times(), _remark_weak_ref_times(),
384 _cleanup_times(),
385 _total_counting_time(0.0),
386 _total_rs_scrub_time(0.0),
387
388 _parallel_workers(NULL),
389
390 _completed_initialization(false) {
391
392 _markBitMap1.initialize(g1h->reserved_region(), prev_bitmap_storage);
393 _markBitMap2.initialize(g1h->reserved_region(), next_bitmap_storage);
394
395 // Create & start a ConcurrentMark thread.
396 _cmThread = new ConcurrentMarkThread(this);
397 assert(cmThread() != NULL, "CM Thread should have been created");
398 assert(cmThread()->cm() != NULL, "CM Thread should refer to this cm");
399 if (_cmThread->osthread() == NULL) {
400 vm_shutdown_during_initialization("Could not create ConcurrentMarkThread");
401 }
402
403 assert(CGC_lock != NULL, "Where's the CGC_lock?");
404 assert(_markBitMap1.covers(g1h->reserved_region()), "_markBitMap1 inconsistency");
405 assert(_markBitMap2.covers(g1h->reserved_region()), "_markBitMap2 inconsistency");
406
407 SATBMarkQueueSet& satb_qs = JavaThread::satb_mark_queue_set();
408 satb_qs.set_buffer_size(G1SATBBufferSize);
409
410 _root_regions.init(_g1h, this);
411
412 if (ConcGCThreads > ParallelGCThreads) {
413 log_warning(gc)("Can't have more ConcGCThreads (%u) than ParallelGCThreads (%u).",
414 ConcGCThreads, ParallelGCThreads);
415 return;
416 }
417 if (!FLAG_IS_DEFAULT(ConcGCThreads) && ConcGCThreads > 0) {
418 // Note: ConcGCThreads has precedence over G1MarkingOverheadPercent
419 // if both are set
420 _sleep_factor = 0.0;
421 _marking_task_overhead = 1.0;
422 } else if (G1MarkingOverheadPercent > 0) {
423 // We will calculate the number of parallel marking threads based
424 // on a target overhead with respect to the soft real-time goal
425 double marking_overhead = (double) G1MarkingOverheadPercent / 100.0;
426 double overall_cm_overhead =
427 (double) MaxGCPauseMillis * marking_overhead /
428 (double) GCPauseIntervalMillis;
429 double cpu_ratio = 1.0 / (double) os::processor_count();
430 double marking_thread_num = ceil(overall_cm_overhead / cpu_ratio);
431 double marking_task_overhead =
432 overall_cm_overhead / marking_thread_num *
433 (double) os::processor_count();
434 double sleep_factor =
435 (1.0 - marking_task_overhead) / marking_task_overhead;
436
437 FLAG_SET_ERGO(uint, ConcGCThreads, (uint) marking_thread_num);
438 _sleep_factor = sleep_factor;
439 _marking_task_overhead = marking_task_overhead;
440 } else {
441 // Calculate the number of parallel marking threads by scaling
442 // the number of parallel GC threads.
443 uint marking_thread_num = scale_parallel_threads(ParallelGCThreads);
444 FLAG_SET_ERGO(uint, ConcGCThreads, marking_thread_num);
445 _sleep_factor = 0.0;
446 _marking_task_overhead = 1.0;
447 }
448
449 assert(ConcGCThreads > 0, "Should have been set");
450 _parallel_marking_threads = ConcGCThreads;
451 _max_parallel_marking_threads = _parallel_marking_threads;
452
453 _parallel_workers = new WorkGang("G1 Marker",
454 _max_parallel_marking_threads, false, true);
455 if (_parallel_workers == NULL) {
456 vm_exit_during_initialization("Failed necessary allocation.");
457 } else {
458 _parallel_workers->initialize_workers();
459 }
460
461 if (FLAG_IS_DEFAULT(MarkStackSize)) {
462 size_t mark_stack_size =
463 MIN2(MarkStackSizeMax,
464 MAX2(MarkStackSize, (size_t) (parallel_marking_threads() * TASKQUEUE_SIZE)));
465 // Verify that the calculated value for MarkStackSize is in range.
466 // It would be nice to use the private utility routine from Arguments.
467 if (!(mark_stack_size >= 1 && mark_stack_size <= MarkStackSizeMax)) {
468 log_warning(gc)("Invalid value calculated for MarkStackSize (" SIZE_FORMAT "): "
469 "must be between 1 and " SIZE_FORMAT,
470 mark_stack_size, MarkStackSizeMax);
471 return;
472 }
473 FLAG_SET_ERGO(size_t, MarkStackSize, mark_stack_size);
474 } else {
475 // Verify MarkStackSize is in range.
476 if (FLAG_IS_CMDLINE(MarkStackSize)) {
477 if (FLAG_IS_DEFAULT(MarkStackSizeMax)) {
478 if (!(MarkStackSize >= 1 && MarkStackSize <= MarkStackSizeMax)) {
479 log_warning(gc)("Invalid value specified for MarkStackSize (" SIZE_FORMAT "): "
480 "must be between 1 and " SIZE_FORMAT,
481 MarkStackSize, MarkStackSizeMax);
482 return;
483 }
484 } else if (FLAG_IS_CMDLINE(MarkStackSizeMax)) {
485 if (!(MarkStackSize >= 1 && MarkStackSize <= MarkStackSizeMax)) {
486 log_warning(gc)("Invalid value specified for MarkStackSize (" SIZE_FORMAT ")"
487 " or for MarkStackSizeMax (" SIZE_FORMAT ")",
488 MarkStackSize, MarkStackSizeMax);
489 return;
490 }
491 }
492 }
493 }
494
495 if (!_markStack.allocate(MarkStackSize)) {
496 log_warning(gc)("Failed to allocate CM marking stack");
497 return;
498 }
499
500 _tasks = NEW_C_HEAP_ARRAY(G1CMTask*, _max_worker_id, mtGC);
501 _accum_task_vtime = NEW_C_HEAP_ARRAY(double, _max_worker_id, mtGC);
502
503 // so that the assertion in MarkingTaskQueue::task_queue doesn't fail
504 _active_tasks = _max_worker_id;
505
506 for (uint i = 0; i < _max_worker_id; ++i) {
507 G1CMTaskQueue* task_queue = new G1CMTaskQueue();
508 task_queue->initialize();
509 _task_queues->register_queue(i, task_queue);
510
511 _tasks[i] = new G1CMTask(i, this, task_queue, _task_queues);
512
513 _accum_task_vtime[i] = 0.0;
514 }
515
516 // so that the call below can read a sensible value
517 _heap_start = g1h->reserved_region().start();
518 set_non_marking_state();
519 _completed_initialization = true;
520 }
521
522 void G1ConcurrentMark::reset() {
523 // Starting values for these two. This should be called in a STW
524 // phase.
525 MemRegion reserved = _g1h->g1_reserved();
526 _heap_start = reserved.start();
527 _heap_end = reserved.end();
528
529 // Separated the asserts so that we know which one fires.
530 assert(_heap_start != NULL, "heap bounds should look ok");
531 assert(_heap_end != NULL, "heap bounds should look ok");
532 assert(_heap_start < _heap_end, "heap bounds should look ok");
533
534 // Reset all the marking data structures and any necessary flags
535 reset_marking_state();
536
537 // We do reset all of them, since different phases will use
538 // different number of active threads. So, it's easiest to have all
539 // of them ready.
540 for (uint i = 0; i < _max_worker_id; ++i) {
541 _tasks[i]->reset(_nextMarkBitMap);
542 }
543
544 // we need this to make sure that the flag is on during the evac
545 // pause with initial mark piggy-backed
546 set_concurrent_marking_in_progress();
547 }
548
549
550 void G1ConcurrentMark::reset_marking_state(bool clear_overflow) {
551 _markStack.set_should_expand();
552 _markStack.setEmpty(); // Also clears the _markStack overflow flag
553 if (clear_overflow) {
554 clear_has_overflown();
555 } else {
556 assert(has_overflown(), "pre-condition");
557 }
558 _finger = _heap_start;
559
560 for (uint i = 0; i < _max_worker_id; ++i) {
561 G1CMTaskQueue* queue = _task_queues->queue(i);
562 queue->set_empty();
563 }
564 }
565
566 void G1ConcurrentMark::set_concurrency(uint active_tasks) {
567 assert(active_tasks <= _max_worker_id, "we should not have more");
568
569 _active_tasks = active_tasks;
570 // Need to update the three data structures below according to the
571 // number of active threads for this phase.
572 _terminator = ParallelTaskTerminator((int) active_tasks, _task_queues);
573 _first_overflow_barrier_sync.set_n_workers((int) active_tasks);
574 _second_overflow_barrier_sync.set_n_workers((int) active_tasks);
575 }
576
577 void G1ConcurrentMark::set_concurrency_and_phase(uint active_tasks, bool concurrent) {
578 set_concurrency(active_tasks);
579
580 _concurrent = concurrent;
581 // We propagate this to all tasks, not just the active ones.
582 for (uint i = 0; i < _max_worker_id; ++i)
583 _tasks[i]->set_concurrent(concurrent);
584
585 if (concurrent) {
586 set_concurrent_marking_in_progress();
587 } else {
588 // We currently assume that the concurrent flag has been set to
589 // false before we start remark. At this point we should also be
590 // in a STW phase.
591 assert(!concurrent_marking_in_progress(), "invariant");
592 assert(out_of_regions(),
593 "only way to get here: _finger: " PTR_FORMAT ", _heap_end: " PTR_FORMAT,
594 p2i(_finger), p2i(_heap_end));
595 }
596 }
597
598 void G1ConcurrentMark::set_non_marking_state() {
599 // We set the global marking state to some default values when we're
600 // not doing marking.
601 reset_marking_state();
602 _active_tasks = 0;
603 clear_concurrent_marking_in_progress();
604 }
605
606 G1ConcurrentMark::~G1ConcurrentMark() {
607 // The G1ConcurrentMark instance is never freed.
608 ShouldNotReachHere();
609 }
610
611 class G1ClearBitMapTask : public AbstractGangTask {
612 // Heap region closure used for clearing the given mark bitmap.
613 class G1ClearBitmapHRClosure : public HeapRegionClosure {
614 private:
615 G1CMBitMap* _bitmap;
616 G1ConcurrentMark* _cm;
617 public:
618 G1ClearBitmapHRClosure(G1CMBitMap* bitmap, G1ConcurrentMark* cm) : HeapRegionClosure(), _cm(cm), _bitmap(bitmap) {
619 }
620
621 virtual bool doHeapRegion(HeapRegion* r) {
622 size_t const chunk_size_in_words = M / HeapWordSize;
623
624 HeapWord* cur = r->bottom();
625 HeapWord* const end = r->end();
626
627 while (cur < end) {
628 MemRegion mr(cur, MIN2(cur + chunk_size_in_words, end));
629 _bitmap->clear_range(mr);
630
631 cur += chunk_size_in_words;
632
633 // Abort iteration if after yielding the marking has been aborted.
634 if (_cm != NULL && _cm->do_yield_check() && _cm->has_aborted()) {
635 return true;
636 }
637 // Repeat the asserts from before the start of the closure. We will do them
638 // as asserts here to minimize their overhead on the product. However, we
639 // will have them as guarantees at the beginning / end of the bitmap
640 // clearing to get some checking in the product.
641 assert(_cm == NULL || _cm->cmThread()->during_cycle(), "invariant");
642 assert(_cm == NULL || !G1CollectedHeap::heap()->collector_state()->mark_in_progress(), "invariant");
643 }
644 assert(cur == end, "Must have completed iteration over the bitmap for region %u.", r->hrm_index());
645
646 return false;
647 }
648 };
649
650 G1ClearBitmapHRClosure _cl;
651 HeapRegionClaimer _hr_claimer;
652 bool _suspendible; // If the task is suspendible, workers must join the STS.
653
654 public:
655 G1ClearBitMapTask(G1CMBitMap* bitmap, G1ConcurrentMark* cm, uint n_workers, bool suspendible) :
656 AbstractGangTask("Parallel Clear Bitmap Task"),
657 _cl(bitmap, suspendible ? cm : NULL),
658 _hr_claimer(n_workers),
659 _suspendible(suspendible)
660 { }
661
662 void work(uint worker_id) {
663 SuspendibleThreadSetJoiner sts_join(_suspendible);
664 G1CollectedHeap::heap()->heap_region_par_iterate(&_cl, worker_id, &_hr_claimer, true);
665 }
666
667 bool is_complete() {
668 return _cl.complete();
669 }
670 };
671
672 void G1ConcurrentMark::clear_bitmap(G1CMBitMap* bitmap, WorkGang* workers, bool may_yield) {
673 assert(may_yield || SafepointSynchronize::is_at_safepoint(), "Non-yielding bitmap clear only allowed at safepoint.");
674
675 G1ClearBitMapTask task(bitmap, this, workers->active_workers(), may_yield);
676 workers->run_task(&task);
677 guarantee(!may_yield || task.is_complete(), "Must have completed iteration when not yielding.");
678 }
679
680 void G1ConcurrentMark::cleanup_for_next_mark() {
681 // Make sure that the concurrent mark thread looks to still be in
682 // the current cycle.
683 guarantee(cmThread()->during_cycle(), "invariant");
684
685 // We are finishing up the current cycle by clearing the next
686 // marking bitmap and getting it ready for the next cycle. During
687 // this time no other cycle can start. So, let's make sure that this
688 // is the case.
689 guarantee(!_g1h->collector_state()->mark_in_progress(), "invariant");
690
691 clear_bitmap(_nextMarkBitMap, _parallel_workers, true);
692
693 // Clear the live count data. If the marking has been aborted, the abort()
694 // call already did that.
695 if (!has_aborted()) {
696 clear_live_data(_parallel_workers);
697 DEBUG_ONLY(verify_live_data_clear());
698 }
699
700 // Repeat the asserts from above.
701 guarantee(cmThread()->during_cycle(), "invariant");
702 guarantee(!_g1h->collector_state()->mark_in_progress(), "invariant");
703 }
704
705 void G1ConcurrentMark::clear_prev_bitmap(WorkGang* workers) {
706 assert(SafepointSynchronize::is_at_safepoint(), "Should only clear the entire prev bitmap at a safepoint.");
707 clear_bitmap((G1CMBitMap*)_prevMarkBitMap, workers, false);
708 }
709
710 class CheckBitmapClearHRClosure : public HeapRegionClosure {
711 G1CMBitMap* _bitmap;
712 bool _error;
713 public:
714 CheckBitmapClearHRClosure(G1CMBitMap* bitmap) : _bitmap(bitmap) {
715 }
716
717 virtual bool doHeapRegion(HeapRegion* r) {
718 // This closure can be called concurrently to the mutator, so we must make sure
719 // that the result of the getNextMarkedWordAddress() call is compared to the
720 // value passed to it as limit to detect any found bits.
721 // end never changes in G1.
722 HeapWord* end = r->end();
723 return _bitmap->getNextMarkedWordAddress(r->bottom(), end) != end;
724 }
725 };
726
727 bool G1ConcurrentMark::nextMarkBitmapIsClear() {
728 CheckBitmapClearHRClosure cl(_nextMarkBitMap);
729 _g1h->heap_region_iterate(&cl);
730 return cl.complete();
731 }
732
733 class NoteStartOfMarkHRClosure: public HeapRegionClosure {
734 public:
735 bool doHeapRegion(HeapRegion* r) {
736 r->note_start_of_marking();
737 return false;
738 }
739 };
740
741 void G1ConcurrentMark::checkpointRootsInitialPre() {
742 G1CollectedHeap* g1h = G1CollectedHeap::heap();
743 G1Policy* g1p = g1h->g1_policy();
744
745 _has_aborted = false;
746
747 // Initialize marking structures. This has to be done in a STW phase.
748 reset();
749
750 // For each region note start of marking.
751 NoteStartOfMarkHRClosure startcl;
752 g1h->heap_region_iterate(&startcl);
753 }
754
755
756 void G1ConcurrentMark::checkpointRootsInitialPost() {
757 G1CollectedHeap* g1h = G1CollectedHeap::heap();
758
759 // Start Concurrent Marking weak-reference discovery.
760 ReferenceProcessor* rp = g1h->ref_processor_cm();
761 // enable ("weak") refs discovery
762 rp->enable_discovery();
763 rp->setup_policy(false); // snapshot the soft ref policy to be used in this cycle
764
765 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
766 // This is the start of the marking cycle, we're expected all
767 // threads to have SATB queues with active set to false.
768 satb_mq_set.set_active_all_threads(true, /* new active value */
769 false /* expected_active */);
770
771 _root_regions.prepare_for_scan();
772
773 // update_g1_committed() will be called at the end of an evac pause
774 // when marking is on. So, it's also called at the end of the
775 // initial-mark pause to update the heap end, if the heap expands
776 // during it. No need to call it here.
777 }
778
779 /*
780 * Notice that in the next two methods, we actually leave the STS
781 * during the barrier sync and join it immediately afterwards. If we
782 * do not do this, the following deadlock can occur: one thread could
783 * be in the barrier sync code, waiting for the other thread to also
784 * sync up, whereas another one could be trying to yield, while also
785 * waiting for the other threads to sync up too.
786 *
787 * Note, however, that this code is also used during remark and in
788 * this case we should not attempt to leave / enter the STS, otherwise
789 * we'll either hit an assert (debug / fastdebug) or deadlock
790 * (product). So we should only leave / enter the STS if we are
791 * operating concurrently.
792 *
793 * Because the thread that does the sync barrier has left the STS, it
794 * is possible to be suspended for a Full GC or an evacuation pause
795 * could occur. This is actually safe, since the entering the sync
796 * barrier is one of the last things do_marking_step() does, and it
797 * doesn't manipulate any data structures afterwards.
798 */
799
800 void G1ConcurrentMark::enter_first_sync_barrier(uint worker_id) {
801 bool barrier_aborted;
802 {
803 SuspendibleThreadSetLeaver sts_leave(concurrent());
804 barrier_aborted = !_first_overflow_barrier_sync.enter();
805 }
806
807 // at this point everyone should have synced up and not be doing any
808 // more work
809
810 if (barrier_aborted) {
811 // If the barrier aborted we ignore the overflow condition and
812 // just abort the whole marking phase as quickly as possible.
813 return;
814 }
815
816 // If we're executing the concurrent phase of marking, reset the marking
817 // state; otherwise the marking state is reset after reference processing,
818 // during the remark pause.
819 // If we reset here as a result of an overflow during the remark we will
820 // see assertion failures from any subsequent set_concurrency_and_phase()
821 // calls.
822 if (concurrent()) {
823 // let the task associated with with worker 0 do this
824 if (worker_id == 0) {
825 // task 0 is responsible for clearing the global data structures
826 // We should be here because of an overflow. During STW we should
827 // not clear the overflow flag since we rely on it being true when
828 // we exit this method to abort the pause and restart concurrent
829 // marking.
830 reset_marking_state(true /* clear_overflow */);
831
832 log_info(gc, marking)("Concurrent Mark reset for overflow");
833 }
834 }
835
836 // after this, each task should reset its own data structures then
837 // then go into the second barrier
838 }
839
840 void G1ConcurrentMark::enter_second_sync_barrier(uint worker_id) {
841 SuspendibleThreadSetLeaver sts_leave(concurrent());
842 _second_overflow_barrier_sync.enter();
843
844 // at this point everything should be re-initialized and ready to go
845 }
846
847 class G1CMConcurrentMarkingTask: public AbstractGangTask {
848 private:
849 G1ConcurrentMark* _cm;
850 ConcurrentMarkThread* _cmt;
851
852 public:
853 void work(uint worker_id) {
854 assert(Thread::current()->is_ConcurrentGC_thread(),
855 "this should only be done by a conc GC thread");
856 ResourceMark rm;
857
858 double start_vtime = os::elapsedVTime();
859
860 {
861 SuspendibleThreadSetJoiner sts_join;
862
863 assert(worker_id < _cm->active_tasks(), "invariant");
864 G1CMTask* the_task = _cm->task(worker_id);
865 the_task->record_start_time();
866 if (!_cm->has_aborted()) {
867 do {
868 double start_vtime_sec = os::elapsedVTime();
869 double mark_step_duration_ms = G1ConcMarkStepDurationMillis;
870
871 the_task->do_marking_step(mark_step_duration_ms,
872 true /* do_termination */,
873 false /* is_serial*/);
874
875 double end_vtime_sec = os::elapsedVTime();
876 double elapsed_vtime_sec = end_vtime_sec - start_vtime_sec;
877 _cm->clear_has_overflown();
878
879 _cm->do_yield_check();
880
881 jlong sleep_time_ms;
882 if (!_cm->has_aborted() && the_task->has_aborted()) {
883 sleep_time_ms =
884 (jlong) (elapsed_vtime_sec * _cm->sleep_factor() * 1000.0);
885 {
886 SuspendibleThreadSetLeaver sts_leave;
887 os::sleep(Thread::current(), sleep_time_ms, false);
888 }
889 }
890 } while (!_cm->has_aborted() && the_task->has_aborted());
891 }
892 the_task->record_end_time();
893 guarantee(!the_task->has_aborted() || _cm->has_aborted(), "invariant");
894 }
895
896 double end_vtime = os::elapsedVTime();
897 _cm->update_accum_task_vtime(worker_id, end_vtime - start_vtime);
898 }
899
900 G1CMConcurrentMarkingTask(G1ConcurrentMark* cm,
901 ConcurrentMarkThread* cmt) :
902 AbstractGangTask("Concurrent Mark"), _cm(cm), _cmt(cmt) { }
903
904 ~G1CMConcurrentMarkingTask() { }
905 };
906
907 // Calculates the number of active workers for a concurrent
908 // phase.
909 uint G1ConcurrentMark::calc_parallel_marking_threads() {
910 uint n_conc_workers = 0;
911 if (!UseDynamicNumberOfGCThreads ||
912 (!FLAG_IS_DEFAULT(ConcGCThreads) &&
913 !ForceDynamicNumberOfGCThreads)) {
914 n_conc_workers = max_parallel_marking_threads();
915 } else {
916 n_conc_workers =
917 AdaptiveSizePolicy::calc_default_active_workers(
918 max_parallel_marking_threads(),
919 1, /* Minimum workers */
920 parallel_marking_threads(),
921 Threads::number_of_non_daemon_threads());
922 // Don't scale down "n_conc_workers" by scale_parallel_threads() because
923 // that scaling has already gone into "_max_parallel_marking_threads".
924 }
925 assert(n_conc_workers > 0, "Always need at least 1");
926 return n_conc_workers;
927 }
928
929 void G1ConcurrentMark::scanRootRegion(HeapRegion* hr) {
930 // Currently, only survivors can be root regions.
931 assert(hr->next_top_at_mark_start() == hr->bottom(), "invariant");
932 G1RootRegionScanClosure cl(_g1h, this);
933
934 const uintx interval = PrefetchScanIntervalInBytes;
935 HeapWord* curr = hr->bottom();
936 const HeapWord* end = hr->top();
937 while (curr < end) {
938 Prefetch::read(curr, interval);
939 oop obj = oop(curr);
940 int size = obj->oop_iterate_size(&cl);
941 assert(size == obj->size(), "sanity");
942 curr += size;
943 }
944 }
945
946 class G1CMRootRegionScanTask : public AbstractGangTask {
947 private:
948 G1ConcurrentMark* _cm;
949
950 public:
951 G1CMRootRegionScanTask(G1ConcurrentMark* cm) :
952 AbstractGangTask("Root Region Scan"), _cm(cm) { }
953
954 void work(uint worker_id) {
955 assert(Thread::current()->is_ConcurrentGC_thread(),
956 "this should only be done by a conc GC thread");
957
958 G1CMRootRegions* root_regions = _cm->root_regions();
959 HeapRegion* hr = root_regions->claim_next();
960 while (hr != NULL) {
961 _cm->scanRootRegion(hr);
962 hr = root_regions->claim_next();
963 }
964 }
965 };
966
967 void G1ConcurrentMark::scan_root_regions() {
968 // scan_in_progress() will have been set to true only if there was
969 // at least one root region to scan. So, if it's false, we
970 // should not attempt to do any further work.
971 if (root_regions()->scan_in_progress()) {
972 assert(!has_aborted(), "Aborting before root region scanning is finished not supported.");
973
974 _parallel_marking_threads = calc_parallel_marking_threads();
975 assert(parallel_marking_threads() <= max_parallel_marking_threads(),
976 "Maximum number of marking threads exceeded");
977 uint active_workers = MAX2(1U, parallel_marking_threads());
978
979 G1CMRootRegionScanTask task(this);
980 _parallel_workers->set_active_workers(active_workers);
981 _parallel_workers->run_task(&task);
982
983 // It's possible that has_aborted() is true here without actually
984 // aborting the survivor scan earlier. This is OK as it's
985 // mainly used for sanity checking.
986 root_regions()->scan_finished();
987 }
988 }
989
990 void G1ConcurrentMark::concurrent_cycle_start() {
991 _gc_timer_cm->register_gc_start();
992
993 _gc_tracer_cm->report_gc_start(GCCause::_no_gc /* first parameter is not used */, _gc_timer_cm->gc_start());
994
995 _g1h->trace_heap_before_gc(_gc_tracer_cm);
996 }
997
998 void G1ConcurrentMark::concurrent_cycle_end() {
999 _g1h->trace_heap_after_gc(_gc_tracer_cm);
1000
1001 if (has_aborted()) {
1002 _gc_tracer_cm->report_concurrent_mode_failure();
1003 }
1004
1005 _gc_timer_cm->register_gc_end();
1006
1007 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
1008 }
1009
1010 void G1ConcurrentMark::mark_from_roots() {
1011 // we might be tempted to assert that:
1012 // assert(asynch == !SafepointSynchronize::is_at_safepoint(),
1013 // "inconsistent argument?");
1014 // However that wouldn't be right, because it's possible that
1015 // a safepoint is indeed in progress as a younger generation
1016 // stop-the-world GC happens even as we mark in this generation.
1017
1018 _restart_for_overflow = false;
1019
1020 // _g1h has _n_par_threads
1021 _parallel_marking_threads = calc_parallel_marking_threads();
1022 assert(parallel_marking_threads() <= max_parallel_marking_threads(),
1023 "Maximum number of marking threads exceeded");
1024
1025 uint active_workers = MAX2(1U, parallel_marking_threads());
1026 assert(active_workers > 0, "Should have been set");
1027
1028 // Parallel task terminator is set in "set_concurrency_and_phase()"
1029 set_concurrency_and_phase(active_workers, true /* concurrent */);
1030
1031 G1CMConcurrentMarkingTask markingTask(this, cmThread());
1032 _parallel_workers->set_active_workers(active_workers);
1033 _parallel_workers->run_task(&markingTask);
1034 print_stats();
1035 }
1036
1037 void G1ConcurrentMark::checkpointRootsFinal(bool clear_all_soft_refs) {
1038 // world is stopped at this checkpoint
1039 assert(SafepointSynchronize::is_at_safepoint(),
1040 "world should be stopped");
1041
1042 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1043
1044 // If a full collection has happened, we shouldn't do this.
1045 if (has_aborted()) {
1046 g1h->collector_state()->set_mark_in_progress(false); // So bitmap clearing isn't confused
1047 return;
1048 }
1049
1050 SvcGCMarker sgcm(SvcGCMarker::OTHER);
1051
1052 if (VerifyDuringGC) {
1053 HandleMark hm; // handle scope
1054 g1h->prepare_for_verify();
1055 Universe::verify(VerifyOption_G1UsePrevMarking, "During GC (before)");
1056 }
1057 g1h->verifier()->check_bitmaps("Remark Start");
1058
1059 G1Policy* g1p = g1h->g1_policy();
1060 g1p->record_concurrent_mark_remark_start();
1061
1062 double start = os::elapsedTime();
1063
1064 checkpointRootsFinalWork();
1065
1066 double mark_work_end = os::elapsedTime();
1067
1068 weakRefsWork(clear_all_soft_refs);
1069
1070 if (has_overflown()) {
1071 // Oops. We overflowed. Restart concurrent marking.
1072 _restart_for_overflow = true;
1073
1074 // Verify the heap w.r.t. the previous marking bitmap.
1075 if (VerifyDuringGC) {
1076 HandleMark hm; // handle scope
1077 g1h->prepare_for_verify();
1078 Universe::verify(VerifyOption_G1UsePrevMarking, "During GC (overflow)");
1079 }
1080
1081 // Clear the marking state because we will be restarting
1082 // marking due to overflowing the global mark stack.
1083 reset_marking_state();
1084 } else {
1085 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
1086 // We're done with marking.
1087 // This is the end of the marking cycle, we're expected all
1088 // threads to have SATB queues with active set to true.
1089 satb_mq_set.set_active_all_threads(false, /* new active value */
1090 true /* expected_active */);
1091
1092 if (VerifyDuringGC) {
1093 HandleMark hm; // handle scope
1094 g1h->prepare_for_verify();
1095 Universe::verify(VerifyOption_G1UseNextMarking, "During GC (after)");
1096 }
1097 g1h->verifier()->check_bitmaps("Remark End");
1098 assert(!restart_for_overflow(), "sanity");
1099 // Completely reset the marking state since marking completed
1100 set_non_marking_state();
1101 }
1102
1103 // Expand the marking stack, if we have to and if we can.
1104 if (_markStack.should_expand()) {
1105 _markStack.expand();
1106 }
1107
1108 // Statistics
1109 double now = os::elapsedTime();
1110 _remark_mark_times.add((mark_work_end - start) * 1000.0);
1111 _remark_weak_ref_times.add((now - mark_work_end) * 1000.0);
1112 _remark_times.add((now - start) * 1000.0);
1113
1114 g1p->record_concurrent_mark_remark_end();
1115
1116 G1CMIsAliveClosure is_alive(g1h);
1117 _gc_tracer_cm->report_object_count_after_gc(&is_alive);
1118 }
1119
1120 class G1NoteEndOfConcMarkClosure : public HeapRegionClosure {
1121 G1CollectedHeap* _g1;
1122 size_t _freed_bytes;
1123 FreeRegionList* _local_cleanup_list;
1124 uint _old_regions_removed;
1125 uint _humongous_regions_removed;
1126 HRRSCleanupTask* _hrrs_cleanup_task;
1127
1128 public:
1129 G1NoteEndOfConcMarkClosure(G1CollectedHeap* g1,
1130 FreeRegionList* local_cleanup_list,
1131 HRRSCleanupTask* hrrs_cleanup_task) :
1132 _g1(g1),
1133 _freed_bytes(0),
1134 _local_cleanup_list(local_cleanup_list),
1135 _old_regions_removed(0),
1136 _humongous_regions_removed(0),
1137 _hrrs_cleanup_task(hrrs_cleanup_task) { }
1138
1139 size_t freed_bytes() { return _freed_bytes; }
1140 const uint old_regions_removed() { return _old_regions_removed; }
1141 const uint humongous_regions_removed() { return _humongous_regions_removed; }
1142
1143 bool doHeapRegion(HeapRegion *hr) {
1144 if (hr->is_archive()) {
1145 return false;
1146 }
1147 _g1->reset_gc_time_stamps(hr);
1148 hr->note_end_of_marking();
1149
1150 if (hr->used() > 0 && hr->max_live_bytes() == 0 && !hr->is_young()) {
1151 _freed_bytes += hr->used();
1152 hr->set_containing_set(NULL);
1153 if (hr->is_humongous()) {
1154 _humongous_regions_removed++;
1155 _g1->free_humongous_region(hr, _local_cleanup_list, true);
1156 } else {
1157 _old_regions_removed++;
1158 _g1->free_region(hr, _local_cleanup_list, true);
1159 }
1160 } else {
1161 hr->rem_set()->do_cleanup_work(_hrrs_cleanup_task);
1162 }
1163
1164 return false;
1165 }
1166 };
1167
1168 class G1ParNoteEndTask: public AbstractGangTask {
1169 friend class G1NoteEndOfConcMarkClosure;
1170
1171 protected:
1172 G1CollectedHeap* _g1h;
1173 FreeRegionList* _cleanup_list;
1174 HeapRegionClaimer _hrclaimer;
1175
1176 public:
1177 G1ParNoteEndTask(G1CollectedHeap* g1h, FreeRegionList* cleanup_list, uint n_workers) :
1178 AbstractGangTask("G1 note end"), _g1h(g1h), _cleanup_list(cleanup_list), _hrclaimer(n_workers) {
1179 }
1180
1181 void work(uint worker_id) {
1182 FreeRegionList local_cleanup_list("Local Cleanup List");
1183 HRRSCleanupTask hrrs_cleanup_task;
1184 G1NoteEndOfConcMarkClosure g1_note_end(_g1h, &local_cleanup_list,
1185 &hrrs_cleanup_task);
1186 _g1h->heap_region_par_iterate(&g1_note_end, worker_id, &_hrclaimer);
1187 assert(g1_note_end.complete(), "Shouldn't have yielded!");
1188
1189 // Now update the lists
1190 _g1h->remove_from_old_sets(g1_note_end.old_regions_removed(), g1_note_end.humongous_regions_removed());
1191 {
1192 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
1193 _g1h->decrement_summary_bytes(g1_note_end.freed_bytes());
1194
1195 // If we iterate over the global cleanup list at the end of
1196 // cleanup to do this printing we will not guarantee to only
1197 // generate output for the newly-reclaimed regions (the list
1198 // might not be empty at the beginning of cleanup; we might
1199 // still be working on its previous contents). So we do the
1200 // printing here, before we append the new regions to the global
1201 // cleanup list.
1202
1203 G1HRPrinter* hr_printer = _g1h->hr_printer();
1204 if (hr_printer->is_active()) {
1205 FreeRegionListIterator iter(&local_cleanup_list);
1206 while (iter.more_available()) {
1207 HeapRegion* hr = iter.get_next();
1208 hr_printer->cleanup(hr);
1209 }
1210 }
1211
1212 _cleanup_list->add_ordered(&local_cleanup_list);
1213 assert(local_cleanup_list.is_empty(), "post-condition");
1214
1215 HeapRegionRemSet::finish_cleanup_task(&hrrs_cleanup_task);
1216 }
1217 }
1218 };
1219
1220 void G1ConcurrentMark::cleanup() {
1221 // world is stopped at this checkpoint
1222 assert(SafepointSynchronize::is_at_safepoint(),
1223 "world should be stopped");
1224 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1225
1226 // If a full collection has happened, we shouldn't do this.
1227 if (has_aborted()) {
1228 g1h->collector_state()->set_mark_in_progress(false); // So bitmap clearing isn't confused
1229 return;
1230 }
1231
1232 g1h->verifier()->verify_region_sets_optional();
1233
1234 if (VerifyDuringGC) {
1235 HandleMark hm; // handle scope
1236 g1h->prepare_for_verify();
1237 Universe::verify(VerifyOption_G1UsePrevMarking, "During GC (before)");
1238 }
1239 g1h->verifier()->check_bitmaps("Cleanup Start");
1240
1241 G1Policy* g1p = g1h->g1_policy();
1242 g1p->record_concurrent_mark_cleanup_start();
1243
1244 double start = os::elapsedTime();
1245
1246 HeapRegionRemSet::reset_for_cleanup_tasks();
1247
1248 {
1249 GCTraceTime(Debug, gc)("Finalize Live Data");
1250 finalize_live_data();
1251 }
1252
1253 if (VerifyDuringGC) {
1254 GCTraceTime(Debug, gc)("Verify Live Data");
1255 verify_live_data();
1256 }
1257
1258 g1h->collector_state()->set_mark_in_progress(false);
1259
1260 double count_end = os::elapsedTime();
1261 double this_final_counting_time = (count_end - start);
1262 _total_counting_time += this_final_counting_time;
1263
1264 if (log_is_enabled(Trace, gc, liveness)) {
1265 G1PrintRegionLivenessInfoClosure cl("Post-Marking");
1266 _g1h->heap_region_iterate(&cl);
1267 }
1268
1269 // Install newly created mark bitMap as "prev".
1270 swapMarkBitMaps();
1271
1272 g1h->reset_gc_time_stamp();
1273
1274 uint n_workers = _g1h->workers()->active_workers();
1275
1276 // Note end of marking in all heap regions.
1277 G1ParNoteEndTask g1_par_note_end_task(g1h, &_cleanup_list, n_workers);
1278 g1h->workers()->run_task(&g1_par_note_end_task);
1279 g1h->check_gc_time_stamps();
1280
1281 if (!cleanup_list_is_empty()) {
1282 // The cleanup list is not empty, so we'll have to process it
1283 // concurrently. Notify anyone else that might be wanting free
1284 // regions that there will be more free regions coming soon.
1285 g1h->set_free_regions_coming();
1286 }
1287
1288 // call below, since it affects the metric by which we sort the heap
1289 // regions.
1290 if (G1ScrubRemSets) {
1291 double rs_scrub_start = os::elapsedTime();
1292 g1h->scrub_rem_set();
1293 _total_rs_scrub_time += (os::elapsedTime() - rs_scrub_start);
1294 }
1295
1296 // this will also free any regions totally full of garbage objects,
1297 // and sort the regions.
1298 g1h->g1_policy()->record_concurrent_mark_cleanup_end();
1299
1300 // Statistics.
1301 double end = os::elapsedTime();
1302 _cleanup_times.add((end - start) * 1000.0);
1303
1304 // Clean up will have freed any regions completely full of garbage.
1305 // Update the soft reference policy with the new heap occupancy.
1306 Universe::update_heap_info_at_gc();
1307
1308 if (VerifyDuringGC) {
1309 HandleMark hm; // handle scope
1310 g1h->prepare_for_verify();
1311 Universe::verify(VerifyOption_G1UsePrevMarking, "During GC (after)");
1312 }
1313
1314 g1h->verifier()->check_bitmaps("Cleanup End");
1315
1316 g1h->verifier()->verify_region_sets_optional();
1317
1318 // We need to make this be a "collection" so any collection pause that
1319 // races with it goes around and waits for completeCleanup to finish.
1320 g1h->increment_total_collections();
1321
1322 // Clean out dead classes and update Metaspace sizes.
1323 if (ClassUnloadingWithConcurrentMark) {
1324 ClassLoaderDataGraph::purge();
1325 }
1326 MetaspaceGC::compute_new_size();
1327
1328 // We reclaimed old regions so we should calculate the sizes to make
1329 // sure we update the old gen/space data.
1330 g1h->g1mm()->update_sizes();
1331 g1h->allocation_context_stats().update_after_mark();
1332 }
1333
1334 void G1ConcurrentMark::complete_cleanup() {
1335 if (has_aborted()) return;
1336
1337 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1338
1339 _cleanup_list.verify_optional();
1340 FreeRegionList tmp_free_list("Tmp Free List");
1341
1342 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [complete cleanup] : "
1343 "cleanup list has %u entries",
1344 _cleanup_list.length());
1345
1346 // No one else should be accessing the _cleanup_list at this point,
1347 // so it is not necessary to take any locks
1348 while (!_cleanup_list.is_empty()) {
1349 HeapRegion* hr = _cleanup_list.remove_region(true /* from_head */);
1350 assert(hr != NULL, "Got NULL from a non-empty list");
1351 hr->par_clear();
1352 tmp_free_list.add_ordered(hr);
1353
1354 // Instead of adding one region at a time to the secondary_free_list,
1355 // we accumulate them in the local list and move them a few at a
1356 // time. This also cuts down on the number of notify_all() calls
1357 // we do during this process. We'll also append the local list when
1358 // _cleanup_list is empty (which means we just removed the last
1359 // region from the _cleanup_list).
1360 if ((tmp_free_list.length() % G1SecondaryFreeListAppendLength == 0) ||
1361 _cleanup_list.is_empty()) {
1362 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [complete cleanup] : "
1363 "appending %u entries to the secondary_free_list, "
1364 "cleanup list still has %u entries",
1365 tmp_free_list.length(),
1366 _cleanup_list.length());
1367
1368 {
1369 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
1370 g1h->secondary_free_list_add(&tmp_free_list);
1371 SecondaryFreeList_lock->notify_all();
1372 }
1373 #ifndef PRODUCT
1374 if (G1StressConcRegionFreeing) {
1375 for (uintx i = 0; i < G1StressConcRegionFreeingDelayMillis; ++i) {
1376 os::sleep(Thread::current(), (jlong) 1, false);
1377 }
1378 }
1379 #endif
1380 }
1381 }
1382 assert(tmp_free_list.is_empty(), "post-condition");
1383 }
1384
1385 // Supporting Object and Oop closures for reference discovery
1386 // and processing in during marking
1387
1388 bool G1CMIsAliveClosure::do_object_b(oop obj) {
1389 HeapWord* addr = (HeapWord*)obj;
1390 return addr != NULL &&
1391 (!_g1->is_in_g1_reserved(addr) || !_g1->is_obj_ill(obj));
1392 }
1393
1394 // 'Keep Alive' oop closure used by both serial parallel reference processing.
1395 // Uses the G1CMTask associated with a worker thread (for serial reference
1396 // processing the G1CMTask for worker 0 is used) to preserve (mark) and
1397 // trace referent objects.
1398 //
1399 // Using the G1CMTask and embedded local queues avoids having the worker
1400 // threads operating on the global mark stack. This reduces the risk
1401 // of overflowing the stack - which we would rather avoid at this late
1402 // state. Also using the tasks' local queues removes the potential
1403 // of the workers interfering with each other that could occur if
1404 // operating on the global stack.
1405
1406 class G1CMKeepAliveAndDrainClosure: public OopClosure {
1407 G1ConcurrentMark* _cm;
1408 G1CMTask* _task;
1409 int _ref_counter_limit;
1410 int _ref_counter;
1411 bool _is_serial;
1412 public:
1413 G1CMKeepAliveAndDrainClosure(G1ConcurrentMark* cm, G1CMTask* task, bool is_serial) :
1414 _cm(cm), _task(task), _is_serial(is_serial),
1415 _ref_counter_limit(G1RefProcDrainInterval) {
1416 assert(_ref_counter_limit > 0, "sanity");
1417 assert(!_is_serial || _task->worker_id() == 0, "only task 0 for serial code");
1418 _ref_counter = _ref_counter_limit;
1419 }
1420
1421 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
1422 virtual void do_oop( oop* p) { do_oop_work(p); }
1423
1424 template <class T> void do_oop_work(T* p) {
1425 if (!_cm->has_overflown()) {
1426 oop obj = oopDesc::load_decode_heap_oop(p);
1427 _task->deal_with_reference(obj);
1428 _ref_counter--;
1429
1430 if (_ref_counter == 0) {
1431 // We have dealt with _ref_counter_limit references, pushing them
1432 // and objects reachable from them on to the local stack (and
1433 // possibly the global stack). Call G1CMTask::do_marking_step() to
1434 // process these entries.
1435 //
1436 // We call G1CMTask::do_marking_step() in a loop, which we'll exit if
1437 // there's nothing more to do (i.e. we're done with the entries that
1438 // were pushed as a result of the G1CMTask::deal_with_reference() calls
1439 // above) or we overflow.
1440 //
1441 // Note: G1CMTask::do_marking_step() can set the G1CMTask::has_aborted()
1442 // flag while there may still be some work to do. (See the comment at
1443 // the beginning of G1CMTask::do_marking_step() for those conditions -
1444 // one of which is reaching the specified time target.) It is only
1445 // when G1CMTask::do_marking_step() returns without setting the
1446 // has_aborted() flag that the marking step has completed.
1447 do {
1448 double mark_step_duration_ms = G1ConcMarkStepDurationMillis;
1449 _task->do_marking_step(mark_step_duration_ms,
1450 false /* do_termination */,
1451 _is_serial);
1452 } while (_task->has_aborted() && !_cm->has_overflown());
1453 _ref_counter = _ref_counter_limit;
1454 }
1455 }
1456 }
1457 };
1458
1459 // 'Drain' oop closure used by both serial and parallel reference processing.
1460 // Uses the G1CMTask associated with a given worker thread (for serial
1461 // reference processing the G1CMtask for worker 0 is used). Calls the
1462 // do_marking_step routine, with an unbelievably large timeout value,
1463 // to drain the marking data structures of the remaining entries
1464 // added by the 'keep alive' oop closure above.
1465
1466 class G1CMDrainMarkingStackClosure: public VoidClosure {
1467 G1ConcurrentMark* _cm;
1468 G1CMTask* _task;
1469 bool _is_serial;
1470 public:
1471 G1CMDrainMarkingStackClosure(G1ConcurrentMark* cm, G1CMTask* task, bool is_serial) :
1472 _cm(cm), _task(task), _is_serial(is_serial) {
1473 assert(!_is_serial || _task->worker_id() == 0, "only task 0 for serial code");
1474 }
1475
1476 void do_void() {
1477 do {
1478 // We call G1CMTask::do_marking_step() to completely drain the local
1479 // and global marking stacks of entries pushed by the 'keep alive'
1480 // oop closure (an instance of G1CMKeepAliveAndDrainClosure above).
1481 //
1482 // G1CMTask::do_marking_step() is called in a loop, which we'll exit
1483 // if there's nothing more to do (i.e. we've completely drained the
1484 // entries that were pushed as a a result of applying the 'keep alive'
1485 // closure to the entries on the discovered ref lists) or we overflow
1486 // the global marking stack.
1487 //
1488 // Note: G1CMTask::do_marking_step() can set the G1CMTask::has_aborted()
1489 // flag while there may still be some work to do. (See the comment at
1490 // the beginning of G1CMTask::do_marking_step() for those conditions -
1491 // one of which is reaching the specified time target.) It is only
1492 // when G1CMTask::do_marking_step() returns without setting the
1493 // has_aborted() flag that the marking step has completed.
1494
1495 _task->do_marking_step(1000000000.0 /* something very large */,
1496 true /* do_termination */,
1497 _is_serial);
1498 } while (_task->has_aborted() && !_cm->has_overflown());
1499 }
1500 };
1501
1502 // Implementation of AbstractRefProcTaskExecutor for parallel
1503 // reference processing at the end of G1 concurrent marking
1504
1505 class G1CMRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
1506 private:
1507 G1CollectedHeap* _g1h;
1508 G1ConcurrentMark* _cm;
1509 WorkGang* _workers;
1510 uint _active_workers;
1511
1512 public:
1513 G1CMRefProcTaskExecutor(G1CollectedHeap* g1h,
1514 G1ConcurrentMark* cm,
1515 WorkGang* workers,
1516 uint n_workers) :
1517 _g1h(g1h), _cm(cm),
1518 _workers(workers), _active_workers(n_workers) { }
1519
1520 // Executes the given task using concurrent marking worker threads.
1521 virtual void execute(ProcessTask& task);
1522 virtual void execute(EnqueueTask& task);
1523 };
1524
1525 class G1CMRefProcTaskProxy: public AbstractGangTask {
1526 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
1527 ProcessTask& _proc_task;
1528 G1CollectedHeap* _g1h;
1529 G1ConcurrentMark* _cm;
1530
1531 public:
1532 G1CMRefProcTaskProxy(ProcessTask& proc_task,
1533 G1CollectedHeap* g1h,
1534 G1ConcurrentMark* cm) :
1535 AbstractGangTask("Process reference objects in parallel"),
1536 _proc_task(proc_task), _g1h(g1h), _cm(cm) {
1537 ReferenceProcessor* rp = _g1h->ref_processor_cm();
1538 assert(rp->processing_is_mt(), "shouldn't be here otherwise");
1539 }
1540
1541 virtual void work(uint worker_id) {
1542 ResourceMark rm;
1543 HandleMark hm;
1544 G1CMTask* task = _cm->task(worker_id);
1545 G1CMIsAliveClosure g1_is_alive(_g1h);
1546 G1CMKeepAliveAndDrainClosure g1_par_keep_alive(_cm, task, false /* is_serial */);
1547 G1CMDrainMarkingStackClosure g1_par_drain(_cm, task, false /* is_serial */);
1548
1549 _proc_task.work(worker_id, g1_is_alive, g1_par_keep_alive, g1_par_drain);
1550 }
1551 };
1552
1553 void G1CMRefProcTaskExecutor::execute(ProcessTask& proc_task) {
1554 assert(_workers != NULL, "Need parallel worker threads.");
1555 assert(_g1h->ref_processor_cm()->processing_is_mt(), "processing is not MT");
1556
1557 G1CMRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _cm);
1558
1559 // We need to reset the concurrency level before each
1560 // proxy task execution, so that the termination protocol
1561 // and overflow handling in G1CMTask::do_marking_step() knows
1562 // how many workers to wait for.
1563 _cm->set_concurrency(_active_workers);
1564 _workers->run_task(&proc_task_proxy);
1565 }
1566
1567 class G1CMRefEnqueueTaskProxy: public AbstractGangTask {
1568 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
1569 EnqueueTask& _enq_task;
1570
1571 public:
1572 G1CMRefEnqueueTaskProxy(EnqueueTask& enq_task) :
1573 AbstractGangTask("Enqueue reference objects in parallel"),
1574 _enq_task(enq_task) { }
1575
1576 virtual void work(uint worker_id) {
1577 _enq_task.work(worker_id);
1578 }
1579 };
1580
1581 void G1CMRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
1582 assert(_workers != NULL, "Need parallel worker threads.");
1583 assert(_g1h->ref_processor_cm()->processing_is_mt(), "processing is not MT");
1584
1585 G1CMRefEnqueueTaskProxy enq_task_proxy(enq_task);
1586
1587 // Not strictly necessary but...
1588 //
1589 // We need to reset the concurrency level before each
1590 // proxy task execution, so that the termination protocol
1591 // and overflow handling in G1CMTask::do_marking_step() knows
1592 // how many workers to wait for.
1593 _cm->set_concurrency(_active_workers);
1594 _workers->run_task(&enq_task_proxy);
1595 }
1596
1597 void G1ConcurrentMark::weakRefsWorkParallelPart(BoolObjectClosure* is_alive, bool purged_classes) {
1598 G1CollectedHeap::heap()->parallel_cleaning(is_alive, true, true, purged_classes);
1599 }
1600
1601 void G1ConcurrentMark::weakRefsWork(bool clear_all_soft_refs) {
1602 if (has_overflown()) {
1603 // Skip processing the discovered references if we have
1604 // overflown the global marking stack. Reference objects
1605 // only get discovered once so it is OK to not
1606 // de-populate the discovered reference lists. We could have,
1607 // but the only benefit would be that, when marking restarts,
1608 // less reference objects are discovered.
1609 return;
1610 }
1611
1612 ResourceMark rm;
1613 HandleMark hm;
1614
1615 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1616
1617 // Is alive closure.
1618 G1CMIsAliveClosure g1_is_alive(g1h);
1619
1620 // Inner scope to exclude the cleaning of the string and symbol
1621 // tables from the displayed time.
1622 {
1623 GCTraceTime(Debug, gc, phases) trace("Reference Processing", _gc_timer_cm);
1624
1625 ReferenceProcessor* rp = g1h->ref_processor_cm();
1626
1627 // See the comment in G1CollectedHeap::ref_processing_init()
1628 // about how reference processing currently works in G1.
1629
1630 // Set the soft reference policy
1631 rp->setup_policy(clear_all_soft_refs);
1632 assert(_markStack.isEmpty(), "mark stack should be empty");
1633
1634 // Instances of the 'Keep Alive' and 'Complete GC' closures used
1635 // in serial reference processing. Note these closures are also
1636 // used for serially processing (by the the current thread) the
1637 // JNI references during parallel reference processing.
1638 //
1639 // These closures do not need to synchronize with the worker
1640 // threads involved in parallel reference processing as these
1641 // instances are executed serially by the current thread (e.g.
1642 // reference processing is not multi-threaded and is thus
1643 // performed by the current thread instead of a gang worker).
1644 //
1645 // The gang tasks involved in parallel reference processing create
1646 // their own instances of these closures, which do their own
1647 // synchronization among themselves.
1648 G1CMKeepAliveAndDrainClosure g1_keep_alive(this, task(0), true /* is_serial */);
1649 G1CMDrainMarkingStackClosure g1_drain_mark_stack(this, task(0), true /* is_serial */);
1650
1651 // We need at least one active thread. If reference processing
1652 // is not multi-threaded we use the current (VMThread) thread,
1653 // otherwise we use the work gang from the G1CollectedHeap and
1654 // we utilize all the worker threads we can.
1655 bool processing_is_mt = rp->processing_is_mt();
1656 uint active_workers = (processing_is_mt ? g1h->workers()->active_workers() : 1U);
1657 active_workers = MAX2(MIN2(active_workers, _max_worker_id), 1U);
1658
1659 // Parallel processing task executor.
1660 G1CMRefProcTaskExecutor par_task_executor(g1h, this,
1661 g1h->workers(), active_workers);
1662 AbstractRefProcTaskExecutor* executor = (processing_is_mt ? &par_task_executor : NULL);
1663
1664 // Set the concurrency level. The phase was already set prior to
1665 // executing the remark task.
1666 set_concurrency(active_workers);
1667
1668 // Set the degree of MT processing here. If the discovery was done MT,
1669 // the number of threads involved during discovery could differ from
1670 // the number of active workers. This is OK as long as the discovered
1671 // Reference lists are balanced (see balance_all_queues() and balance_queues()).
1672 rp->set_active_mt_degree(active_workers);
1673
1674 // Process the weak references.
1675 const ReferenceProcessorStats& stats =
1676 rp->process_discovered_references(&g1_is_alive,
1677 &g1_keep_alive,
1678 &g1_drain_mark_stack,
1679 executor,
1680 _gc_timer_cm);
1681 _gc_tracer_cm->report_gc_reference_stats(stats);
1682
1683 // The do_oop work routines of the keep_alive and drain_marking_stack
1684 // oop closures will set the has_overflown flag if we overflow the
1685 // global marking stack.
1686
1687 assert(_markStack.overflow() || _markStack.isEmpty(),
1688 "mark stack should be empty (unless it overflowed)");
1689
1690 if (_markStack.overflow()) {
1691 // This should have been done already when we tried to push an
1692 // entry on to the global mark stack. But let's do it again.
1693 set_has_overflown();
1694 }
1695
1696 assert(rp->num_q() == active_workers, "why not");
1697
1698 rp->enqueue_discovered_references(executor);
1699
1700 rp->verify_no_references_recorded();
1701 assert(!rp->discovery_enabled(), "Post condition");
1702 }
1703
1704 if (has_overflown()) {
1705 // We can not trust g1_is_alive if the marking stack overflowed
1706 return;
1707 }
1708
1709 assert(_markStack.isEmpty(), "Marking should have completed");
1710
1711 // Unload Klasses, String, Symbols, Code Cache, etc.
1712 if (ClassUnloadingWithConcurrentMark) {
1713 bool purged_classes;
1714
1715 {
1716 GCTraceTime(Debug, gc, phases) trace("System Dictionary Unloading", _gc_timer_cm);
1717 purged_classes = SystemDictionary::do_unloading(&g1_is_alive, false /* Defer klass cleaning */);
1718 }
1719
1720 {
1721 GCTraceTime(Debug, gc, phases) trace("Parallel Unloading", _gc_timer_cm);
1722 weakRefsWorkParallelPart(&g1_is_alive, purged_classes);
1723 }
1724 }
1725
1726 if (G1StringDedup::is_enabled()) {
1727 GCTraceTime(Debug, gc, phases) trace("String Deduplication Unlink", _gc_timer_cm);
1728 G1StringDedup::unlink(&g1_is_alive);
1729 }
1730 }
1731
1732 void G1ConcurrentMark::swapMarkBitMaps() {
1733 G1CMBitMapRO* temp = _prevMarkBitMap;
1734 _prevMarkBitMap = (G1CMBitMapRO*)_nextMarkBitMap;
1735 _nextMarkBitMap = (G1CMBitMap*) temp;
1736 }
1737
1738 // Closure for marking entries in SATB buffers.
1739 class G1CMSATBBufferClosure : public SATBBufferClosure {
1740 private:
1741 G1CMTask* _task;
1742 G1CollectedHeap* _g1h;
1743
1744 // This is very similar to G1CMTask::deal_with_reference, but with
1745 // more relaxed requirements for the argument, so this must be more
1746 // circumspect about treating the argument as an object.
1747 void do_entry(void* entry) const {
1748 _task->increment_refs_reached();
1749 HeapRegion* hr = _g1h->heap_region_containing(entry);
1750 if (entry < hr->next_top_at_mark_start()) {
1751 // Until we get here, we don't know whether entry refers to a valid
1752 // object; it could instead have been a stale reference.
1753 oop obj = static_cast<oop>(entry);
1754 assert(obj->is_oop(true /* ignore mark word */),
1755 "Invalid oop in SATB buffer: " PTR_FORMAT, p2i(obj));
1756 _task->make_reference_grey(obj);
1757 }
1758 }
1759
1760 public:
1761 G1CMSATBBufferClosure(G1CMTask* task, G1CollectedHeap* g1h)
1762 : _task(task), _g1h(g1h) { }
1763
1764 virtual void do_buffer(void** buffer, size_t size) {
1765 for (size_t i = 0; i < size; ++i) {
1766 do_entry(buffer[i]);
1767 }
1768 }
1769 };
1770
1771 class G1RemarkThreadsClosure : public ThreadClosure {
1772 G1CMSATBBufferClosure _cm_satb_cl;
1773 G1CMOopClosure _cm_cl;
1774 MarkingCodeBlobClosure _code_cl;
1775 int _thread_parity;
1776
1777 public:
1778 G1RemarkThreadsClosure(G1CollectedHeap* g1h, G1CMTask* task) :
1779 _cm_satb_cl(task, g1h),
1780 _cm_cl(g1h, g1h->concurrent_mark(), task),
1781 _code_cl(&_cm_cl, !CodeBlobToOopClosure::FixRelocations),
1782 _thread_parity(Threads::thread_claim_parity()) {}
1783
1784 void do_thread(Thread* thread) {
1785 if (thread->is_Java_thread()) {
1786 if (thread->claim_oops_do(true, _thread_parity)) {
1787 JavaThread* jt = (JavaThread*)thread;
1788
1789 // In theory it should not be neccessary to explicitly walk the nmethods to find roots for concurrent marking
1790 // however the liveness of oops reachable from nmethods have very complex lifecycles:
1791 // * Alive if on the stack of an executing method
1792 // * Weakly reachable otherwise
1793 // Some objects reachable from nmethods, such as the class loader (or klass_holder) of the receiver should be
1794 // live by the SATB invariant but other oops recorded in nmethods may behave differently.
1795 jt->nmethods_do(&_code_cl);
1796
1797 jt->satb_mark_queue().apply_closure_and_empty(&_cm_satb_cl);
1798 }
1799 } else if (thread->is_VM_thread()) {
1800 if (thread->claim_oops_do(true, _thread_parity)) {
1801 JavaThread::satb_mark_queue_set().shared_satb_queue()->apply_closure_and_empty(&_cm_satb_cl);
1802 }
1803 }
1804 }
1805 };
1806
1807 class G1CMRemarkTask: public AbstractGangTask {
1808 private:
1809 G1ConcurrentMark* _cm;
1810 public:
1811 void work(uint worker_id) {
1812 // Since all available tasks are actually started, we should
1813 // only proceed if we're supposed to be active.
1814 if (worker_id < _cm->active_tasks()) {
1815 G1CMTask* task = _cm->task(worker_id);
1816 task->record_start_time();
1817 {
1818 ResourceMark rm;
1819 HandleMark hm;
1820
1821 G1RemarkThreadsClosure threads_f(G1CollectedHeap::heap(), task);
1822 Threads::threads_do(&threads_f);
1823 }
1824
1825 do {
1826 task->do_marking_step(1000000000.0 /* something very large */,
1827 true /* do_termination */,
1828 false /* is_serial */);
1829 } while (task->has_aborted() && !_cm->has_overflown());
1830 // If we overflow, then we do not want to restart. We instead
1831 // want to abort remark and do concurrent marking again.
1832 task->record_end_time();
1833 }
1834 }
1835
1836 G1CMRemarkTask(G1ConcurrentMark* cm, uint active_workers) :
1837 AbstractGangTask("Par Remark"), _cm(cm) {
1838 _cm->terminator()->reset_for_reuse(active_workers);
1839 }
1840 };
1841
1842 void G1ConcurrentMark::checkpointRootsFinalWork() {
1843 ResourceMark rm;
1844 HandleMark hm;
1845 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1846
1847 GCTraceTime(Debug, gc, phases) trace("Finalize Marking", _gc_timer_cm);
1848
1849 g1h->ensure_parsability(false);
1850
1851 // this is remark, so we'll use up all active threads
1852 uint active_workers = g1h->workers()->active_workers();
1853 set_concurrency_and_phase(active_workers, false /* concurrent */);
1854 // Leave _parallel_marking_threads at it's
1855 // value originally calculated in the G1ConcurrentMark
1856 // constructor and pass values of the active workers
1857 // through the gang in the task.
1858
1859 {
1860 StrongRootsScope srs(active_workers);
1861
1862 G1CMRemarkTask remarkTask(this, active_workers);
1863 // We will start all available threads, even if we decide that the
1864 // active_workers will be fewer. The extra ones will just bail out
1865 // immediately.
1866 g1h->workers()->run_task(&remarkTask);
1867 }
1868
1869 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
1870 guarantee(has_overflown() ||
1871 satb_mq_set.completed_buffers_num() == 0,
1872 "Invariant: has_overflown = %s, num buffers = " SIZE_FORMAT,
1873 BOOL_TO_STR(has_overflown()),
1874 satb_mq_set.completed_buffers_num());
1875
1876 print_stats();
1877 }
1878
1879 void G1ConcurrentMark::clearRangePrevBitmap(MemRegion mr) {
1880 // Note we are overriding the read-only view of the prev map here, via
1881 // the cast.
1882 ((G1CMBitMap*)_prevMarkBitMap)->clear_range(mr);
1883 }
1884
1885 HeapRegion*
1886 G1ConcurrentMark::claim_region(uint worker_id) {
1887 // "checkpoint" the finger
1888 HeapWord* finger = _finger;
1889
1890 // _heap_end will not change underneath our feet; it only changes at
1891 // yield points.
1892 while (finger < _heap_end) {
1893 assert(_g1h->is_in_g1_reserved(finger), "invariant");
1894
1895 HeapRegion* curr_region = _g1h->heap_region_containing(finger);
1896
1897 // Above heap_region_containing may return NULL as we always scan claim
1898 // until the end of the heap. In this case, just jump to the next region.
1899 HeapWord* end = curr_region != NULL ? curr_region->end() : finger + HeapRegion::GrainWords;
1900
1901 // Is the gap between reading the finger and doing the CAS too long?
1902 HeapWord* res = (HeapWord*) Atomic::cmpxchg_ptr(end, &_finger, finger);
1903 if (res == finger && curr_region != NULL) {
1904 // we succeeded
1905 HeapWord* bottom = curr_region->bottom();
1906 HeapWord* limit = curr_region->next_top_at_mark_start();
1907
1908 // notice that _finger == end cannot be guaranteed here since,
1909 // someone else might have moved the finger even further
1910 assert(_finger >= end, "the finger should have moved forward");
1911
1912 if (limit > bottom) {
1913 return curr_region;
1914 } else {
1915 assert(limit == bottom,
1916 "the region limit should be at bottom");
1917 // we return NULL and the caller should try calling
1918 // claim_region() again.
1919 return NULL;
1920 }
1921 } else {
1922 assert(_finger > finger, "the finger should have moved forward");
1923 // read it again
1924 finger = _finger;
1925 }
1926 }
1927
1928 return NULL;
1929 }
1930
1931 #ifndef PRODUCT
1932 class VerifyNoCSetOops VALUE_OBJ_CLASS_SPEC {
1933 private:
1934 G1CollectedHeap* _g1h;
1935 const char* _phase;
1936 int _info;
1937
1938 public:
1939 VerifyNoCSetOops(const char* phase, int info = -1) :
1940 _g1h(G1CollectedHeap::heap()),
1941 _phase(phase),
1942 _info(info)
1943 { }
1944
1945 void operator()(oop obj) const {
1946 guarantee(obj->is_oop(),
1947 "Non-oop " PTR_FORMAT ", phase: %s, info: %d",
1948 p2i(obj), _phase, _info);
1949 guarantee(!_g1h->obj_in_cs(obj),
1950 "obj: " PTR_FORMAT " in CSet, phase: %s, info: %d",
1951 p2i(obj), _phase, _info);
1952 }
1953 };
1954
1955 void G1ConcurrentMark::verify_no_cset_oops() {
1956 assert(SafepointSynchronize::is_at_safepoint(), "should be at a safepoint");
1957 if (!G1CollectedHeap::heap()->collector_state()->mark_in_progress()) {
1958 return;
1959 }
1960
1961 // Verify entries on the global mark stack
1962 _markStack.iterate(VerifyNoCSetOops("Stack"));
1963
1964 // Verify entries on the task queues
1965 for (uint i = 0; i < _max_worker_id; ++i) {
1966 G1CMTaskQueue* queue = _task_queues->queue(i);
1967 queue->iterate(VerifyNoCSetOops("Queue", i));
1968 }
1969
1970 // Verify the global finger
1971 HeapWord* global_finger = finger();
1972 if (global_finger != NULL && global_finger < _heap_end) {
1973 // Since we always iterate over all regions, we might get a NULL HeapRegion
1974 // here.
1975 HeapRegion* global_hr = _g1h->heap_region_containing(global_finger);
1976 guarantee(global_hr == NULL || global_finger == global_hr->bottom(),
1977 "global finger: " PTR_FORMAT " region: " HR_FORMAT,
1978 p2i(global_finger), HR_FORMAT_PARAMS(global_hr));
1979 }
1980
1981 // Verify the task fingers
1982 assert(parallel_marking_threads() <= _max_worker_id, "sanity");
1983 for (uint i = 0; i < parallel_marking_threads(); ++i) {
1984 G1CMTask* task = _tasks[i];
1985 HeapWord* task_finger = task->finger();
1986 if (task_finger != NULL && task_finger < _heap_end) {
1987 // See above note on the global finger verification.
1988 HeapRegion* task_hr = _g1h->heap_region_containing(task_finger);
1989 guarantee(task_hr == NULL || task_finger == task_hr->bottom() ||
1990 !task_hr->in_collection_set(),
1991 "task finger: " PTR_FORMAT " region: " HR_FORMAT,
1992 p2i(task_finger), HR_FORMAT_PARAMS(task_hr));
1993 }
1994 }
1995 }
1996 #endif // PRODUCT
1997 void G1ConcurrentMark::create_live_data() {
1998 _g1h->g1_rem_set()->create_card_live_data(_parallel_workers, _nextMarkBitMap);
1999 }
2000
2001 void G1ConcurrentMark::finalize_live_data() {
2002 _g1h->g1_rem_set()->finalize_card_live_data(_g1h->workers(), _nextMarkBitMap);
2003 }
2004
2005 void G1ConcurrentMark::verify_live_data() {
2006 _g1h->g1_rem_set()->verify_card_live_data(_g1h->workers(), _nextMarkBitMap);
2007 }
2008
2009 void G1ConcurrentMark::clear_live_data(WorkGang* workers) {
2010 _g1h->g1_rem_set()->clear_card_live_data(workers);
2011 }
2012
2013 #ifdef ASSERT
2014 void G1ConcurrentMark::verify_live_data_clear() {
2015 _g1h->g1_rem_set()->verify_card_live_data_is_clear();
2016 }
2017 #endif
2018
2019 void G1ConcurrentMark::print_stats() {
2020 if (!log_is_enabled(Debug, gc, stats)) {
2021 return;
2022 }
2023 log_debug(gc, stats)("---------------------------------------------------------------------");
2024 for (size_t i = 0; i < _active_tasks; ++i) {
2025 _tasks[i]->print_stats();
2026 log_debug(gc, stats)("---------------------------------------------------------------------");
2027 }
2028 }
2029
2030 void G1ConcurrentMark::abort() {
2031 if (!cmThread()->during_cycle() || _has_aborted) {
2032 // We haven't started a concurrent cycle or we have already aborted it. No need to do anything.
2033 return;
2034 }
2035
2036 // Clear all marks in the next bitmap for the next marking cycle. This will allow us to skip the next
2037 // concurrent bitmap clearing.
2038 {
2039 GCTraceTime(Debug, gc)("Clear Next Bitmap");
2040 clear_bitmap(_nextMarkBitMap, _g1h->workers(), false);
2041 }
2042 // Note we cannot clear the previous marking bitmap here
2043 // since VerifyDuringGC verifies the objects marked during
2044 // a full GC against the previous bitmap.
2045
2046 {
2047 GCTraceTime(Debug, gc)("Clear Live Data");
2048 clear_live_data(_g1h->workers());
2049 }
2050 DEBUG_ONLY({
2051 GCTraceTime(Debug, gc)("Verify Live Data Clear");
2052 verify_live_data_clear();
2053 })
2054 // Empty mark stack
2055 reset_marking_state();
2056 for (uint i = 0; i < _max_worker_id; ++i) {
2057 _tasks[i]->clear_region_fields();
2058 }
2059 _first_overflow_barrier_sync.abort();
2060 _second_overflow_barrier_sync.abort();
2061 _has_aborted = true;
2062
2063 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
2064 satb_mq_set.abandon_partial_marking();
2065 // This can be called either during or outside marking, we'll read
2066 // the expected_active value from the SATB queue set.
2067 satb_mq_set.set_active_all_threads(
2068 false, /* new active value */
2069 satb_mq_set.is_active() /* expected_active */);
2070 }
2071
2072 static void print_ms_time_info(const char* prefix, const char* name,
2073 NumberSeq& ns) {
2074 log_trace(gc, marking)("%s%5d %12s: total time = %8.2f s (avg = %8.2f ms).",
2075 prefix, ns.num(), name, ns.sum()/1000.0, ns.avg());
2076 if (ns.num() > 0) {
2077 log_trace(gc, marking)("%s [std. dev = %8.2f ms, max = %8.2f ms]",
2078 prefix, ns.sd(), ns.maximum());
2079 }
2080 }
2081
2082 void G1ConcurrentMark::print_summary_info() {
2083 Log(gc, marking) log;
2084 if (!log.is_trace()) {
2085 return;
2086 }
2087
2088 log.trace(" Concurrent marking:");
2089 print_ms_time_info(" ", "init marks", _init_times);
2090 print_ms_time_info(" ", "remarks", _remark_times);
2091 {
2092 print_ms_time_info(" ", "final marks", _remark_mark_times);
2093 print_ms_time_info(" ", "weak refs", _remark_weak_ref_times);
2094
2095 }
2096 print_ms_time_info(" ", "cleanups", _cleanup_times);
2097 log.trace(" Finalize live data total time = %8.2f s (avg = %8.2f ms).",
2098 _total_counting_time, (_cleanup_times.num() > 0 ? _total_counting_time * 1000.0 / (double)_cleanup_times.num() : 0.0));
2099 if (G1ScrubRemSets) {
2100 log.trace(" RS scrub total time = %8.2f s (avg = %8.2f ms).",
2101 _total_rs_scrub_time, (_cleanup_times.num() > 0 ? _total_rs_scrub_time * 1000.0 / (double)_cleanup_times.num() : 0.0));
2102 }
2103 log.trace(" Total stop_world time = %8.2f s.",
2104 (_init_times.sum() + _remark_times.sum() + _cleanup_times.sum())/1000.0);
2105 log.trace(" Total concurrent time = %8.2f s (%8.2f s marking).",
2106 cmThread()->vtime_accum(), cmThread()->vtime_mark_accum());
2107 }
2108
2109 void G1ConcurrentMark::print_worker_threads_on(outputStream* st) const {
2110 _parallel_workers->print_worker_threads_on(st);
2111 }
2112
2113 void G1ConcurrentMark::threads_do(ThreadClosure* tc) const {
2114 _parallel_workers->threads_do(tc);
2115 }
2116
2117 void G1ConcurrentMark::print_on_error(outputStream* st) const {
2118 st->print_cr("Marking Bits (Prev, Next): (CMBitMap*) " PTR_FORMAT ", (CMBitMap*) " PTR_FORMAT,
2119 p2i(_prevMarkBitMap), p2i(_nextMarkBitMap));
2120 _prevMarkBitMap->print_on_error(st, " Prev Bits: ");
2121 _nextMarkBitMap->print_on_error(st, " Next Bits: ");
2122 }
2123
2124 // Closure for iteration over bitmaps
2125 class G1CMBitMapClosure : public BitMapClosure {
2126 private:
2127 // the bitmap that is being iterated over
2128 G1CMBitMap* _nextMarkBitMap;
2129 G1ConcurrentMark* _cm;
2130 G1CMTask* _task;
2131
2132 public:
2133 G1CMBitMapClosure(G1CMTask *task, G1ConcurrentMark* cm, G1CMBitMap* nextMarkBitMap) :
2134 _task(task), _cm(cm), _nextMarkBitMap(nextMarkBitMap) { }
2135
2136 bool do_bit(size_t offset) {
2137 HeapWord* addr = _nextMarkBitMap->offsetToHeapWord(offset);
2138 assert(_nextMarkBitMap->isMarked(addr), "invariant");
2139 assert( addr < _cm->finger(), "invariant");
2140 assert(addr >= _task->finger(), "invariant");
2141
2142 // We move that task's local finger along.
2143 _task->move_finger_to(addr);
2144
2145 _task->scan_object(oop(addr));
2146 // we only partially drain the local queue and global stack
2147 _task->drain_local_queue(true);
2148 _task->drain_global_stack(true);
2149
2150 // if the has_aborted flag has been raised, we need to bail out of
2151 // the iteration
2152 return !_task->has_aborted();
2153 }
2154 };
2155
2156 static ReferenceProcessor* get_cm_oop_closure_ref_processor(G1CollectedHeap* g1h) {
2157 ReferenceProcessor* result = g1h->ref_processor_cm();
2158 assert(result != NULL, "CM reference processor should not be NULL");
2159 return result;
2160 }
2161
2162 G1CMOopClosure::G1CMOopClosure(G1CollectedHeap* g1h,
2163 G1ConcurrentMark* cm,
2164 G1CMTask* task)
2165 : MetadataAwareOopClosure(get_cm_oop_closure_ref_processor(g1h)),
2166 _g1h(g1h), _cm(cm), _task(task)
2167 { }
2168
2169 void G1CMTask::setup_for_region(HeapRegion* hr) {
2170 assert(hr != NULL,
2171 "claim_region() should have filtered out NULL regions");
2172 _curr_region = hr;
2173 _finger = hr->bottom();
2174 update_region_limit();
2175 }
2176
2177 void G1CMTask::update_region_limit() {
2178 HeapRegion* hr = _curr_region;
2179 HeapWord* bottom = hr->bottom();
2180 HeapWord* limit = hr->next_top_at_mark_start();
2181
2182 if (limit == bottom) {
2183 // The region was collected underneath our feet.
2184 // We set the finger to bottom to ensure that the bitmap
2185 // iteration that will follow this will not do anything.
2186 // (this is not a condition that holds when we set the region up,
2187 // as the region is not supposed to be empty in the first place)
2188 _finger = bottom;
2189 } else if (limit >= _region_limit) {
2190 assert(limit >= _finger, "peace of mind");
2191 } else {
2192 assert(limit < _region_limit, "only way to get here");
2193 // This can happen under some pretty unusual circumstances. An
2194 // evacuation pause empties the region underneath our feet (NTAMS
2195 // at bottom). We then do some allocation in the region (NTAMS
2196 // stays at bottom), followed by the region being used as a GC
2197 // alloc region (NTAMS will move to top() and the objects
2198 // originally below it will be grayed). All objects now marked in
2199 // the region are explicitly grayed, if below the global finger,
2200 // and we do not need in fact to scan anything else. So, we simply
2201 // set _finger to be limit to ensure that the bitmap iteration
2202 // doesn't do anything.
2203 _finger = limit;
2204 }
2205
2206 _region_limit = limit;
2207 }
2208
2209 void G1CMTask::giveup_current_region() {
2210 assert(_curr_region != NULL, "invariant");
2211 clear_region_fields();
2212 }
2213
2214 void G1CMTask::clear_region_fields() {
2215 // Values for these three fields that indicate that we're not
2216 // holding on to a region.
2217 _curr_region = NULL;
2218 _finger = NULL;
2219 _region_limit = NULL;
2220 }
2221
2222 void G1CMTask::set_cm_oop_closure(G1CMOopClosure* cm_oop_closure) {
2223 if (cm_oop_closure == NULL) {
2224 assert(_cm_oop_closure != NULL, "invariant");
2225 } else {
2226 assert(_cm_oop_closure == NULL, "invariant");
2227 }
2228 _cm_oop_closure = cm_oop_closure;
2229 }
2230
2231 void G1CMTask::reset(G1CMBitMap* nextMarkBitMap) {
2232 guarantee(nextMarkBitMap != NULL, "invariant");
2233 _nextMarkBitMap = nextMarkBitMap;
2234 clear_region_fields();
2235
2236 _calls = 0;
2237 _elapsed_time_ms = 0.0;
2238 _termination_time_ms = 0.0;
2239 _termination_start_time_ms = 0.0;
2240 }
2241
2242 bool G1CMTask::should_exit_termination() {
2243 regular_clock_call();
2244 // This is called when we are in the termination protocol. We should
2245 // quit if, for some reason, this task wants to abort or the global
2246 // stack is not empty (this means that we can get work from it).
2247 return !_cm->mark_stack_empty() || has_aborted();
2248 }
2249
2250 void G1CMTask::reached_limit() {
2251 assert(_words_scanned >= _words_scanned_limit ||
2252 _refs_reached >= _refs_reached_limit ,
2253 "shouldn't have been called otherwise");
2254 regular_clock_call();
2255 }
2256
2257 void G1CMTask::regular_clock_call() {
2258 if (has_aborted()) return;
2259
2260 // First, we need to recalculate the words scanned and refs reached
2261 // limits for the next clock call.
2262 recalculate_limits();
2263
2264 // During the regular clock call we do the following
2265
2266 // (1) If an overflow has been flagged, then we abort.
2267 if (_cm->has_overflown()) {
2268 set_has_aborted();
2269 return;
2270 }
2271
2272 // If we are not concurrent (i.e. we're doing remark) we don't need
2273 // to check anything else. The other steps are only needed during
2274 // the concurrent marking phase.
2275 if (!concurrent()) return;
2276
2277 // (2) If marking has been aborted for Full GC, then we also abort.
2278 if (_cm->has_aborted()) {
2279 set_has_aborted();
2280 return;
2281 }
2282
2283 double curr_time_ms = os::elapsedVTime() * 1000.0;
2284
2285 // (4) We check whether we should yield. If we have to, then we abort.
2286 if (SuspendibleThreadSet::should_yield()) {
2287 // We should yield. To do this we abort the task. The caller is
2288 // responsible for yielding.
2289 set_has_aborted();
2290 return;
2291 }
2292
2293 // (5) We check whether we've reached our time quota. If we have,
2294 // then we abort.
2295 double elapsed_time_ms = curr_time_ms - _start_time_ms;
2296 if (elapsed_time_ms > _time_target_ms) {
2297 set_has_aborted();
2298 _has_timed_out = true;
2299 return;
2300 }
2301
2302 // (6) Finally, we check whether there are enough completed STAB
2303 // buffers available for processing. If there are, we abort.
2304 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
2305 if (!_draining_satb_buffers && satb_mq_set.process_completed_buffers()) {
2306 // we do need to process SATB buffers, we'll abort and restart
2307 // the marking task to do so
2308 set_has_aborted();
2309 return;
2310 }
2311 }
2312
2313 void G1CMTask::recalculate_limits() {
2314 _real_words_scanned_limit = _words_scanned + words_scanned_period;
2315 _words_scanned_limit = _real_words_scanned_limit;
2316
2317 _real_refs_reached_limit = _refs_reached + refs_reached_period;
2318 _refs_reached_limit = _real_refs_reached_limit;
2319 }
2320
2321 void G1CMTask::decrease_limits() {
2322 // This is called when we believe that we're going to do an infrequent
2323 // operation which will increase the per byte scanned cost (i.e. move
2324 // entries to/from the global stack). It basically tries to decrease the
2325 // scanning limit so that the clock is called earlier.
2326
2327 _words_scanned_limit = _real_words_scanned_limit -
2328 3 * words_scanned_period / 4;
2329 _refs_reached_limit = _real_refs_reached_limit -
2330 3 * refs_reached_period / 4;
2331 }
2332
2333 void G1CMTask::move_entries_to_global_stack() {
2334 // local array where we'll store the entries that will be popped
2335 // from the local queue
2336 oop buffer[global_stack_transfer_size];
2337
2338 int n = 0;
2339 oop obj;
2340 while (n < global_stack_transfer_size && _task_queue->pop_local(obj)) {
2341 buffer[n] = obj;
2342 ++n;
2343 }
2344
2345 if (n > 0) {
2346 // we popped at least one entry from the local queue
2347
2348 if (!_cm->mark_stack_push(buffer, n)) {
2349 set_has_aborted();
2350 }
2351 }
2352
2353 // this operation was quite expensive, so decrease the limits
2354 decrease_limits();
2355 }
2356
2357 void G1CMTask::get_entries_from_global_stack() {
2358 // local array where we'll store the entries that will be popped
2359 // from the global stack.
2360 oop buffer[global_stack_transfer_size];
2361 int n;
2362 _cm->mark_stack_pop(buffer, global_stack_transfer_size, &n);
2363 assert(n <= global_stack_transfer_size,
2364 "we should not pop more than the given limit");
2365 if (n > 0) {
2366 // yes, we did actually pop at least one entry
2367 for (int i = 0; i < n; ++i) {
2368 bool success = _task_queue->push(buffer[i]);
2369 // We only call this when the local queue is empty or under a
2370 // given target limit. So, we do not expect this push to fail.
2371 assert(success, "invariant");
2372 }
2373 }
2374
2375 // this operation was quite expensive, so decrease the limits
2376 decrease_limits();
2377 }
2378
2379 void G1CMTask::drain_local_queue(bool partially) {
2380 if (has_aborted()) return;
2381
2382 // Decide what the target size is, depending whether we're going to
2383 // drain it partially (so that other tasks can steal if they run out
2384 // of things to do) or totally (at the very end).
2385 size_t target_size;
2386 if (partially) {
2387 target_size = MIN2((size_t)_task_queue->max_elems()/3, GCDrainStackTargetSize);
2388 } else {
2389 target_size = 0;
2390 }
2391
2392 if (_task_queue->size() > target_size) {
2393 oop obj;
2394 bool ret = _task_queue->pop_local(obj);
2395 while (ret) {
2396 assert(_g1h->is_in_g1_reserved((HeapWord*) obj), "invariant" );
2397 assert(!_g1h->is_on_master_free_list(
2398 _g1h->heap_region_containing((HeapWord*) obj)), "invariant");
2399
2400 scan_object(obj);
2401
2402 if (_task_queue->size() <= target_size || has_aborted()) {
2403 ret = false;
2404 } else {
2405 ret = _task_queue->pop_local(obj);
2406 }
2407 }
2408 }
2409 }
2410
2411 void G1CMTask::drain_global_stack(bool partially) {
2412 if (has_aborted()) return;
2413
2414 // We have a policy to drain the local queue before we attempt to
2415 // drain the global stack.
2416 assert(partially || _task_queue->size() == 0, "invariant");
2417
2418 // Decide what the target size is, depending whether we're going to
2419 // drain it partially (so that other tasks can steal if they run out
2420 // of things to do) or totally (at the very end). Notice that,
2421 // because we move entries from the global stack in chunks or
2422 // because another task might be doing the same, we might in fact
2423 // drop below the target. But, this is not a problem.
2424 size_t target_size;
2425 if (partially) {
2426 target_size = _cm->partial_mark_stack_size_target();
2427 } else {
2428 target_size = 0;
2429 }
2430
2431 if (_cm->mark_stack_size() > target_size) {
2432 while (!has_aborted() && _cm->mark_stack_size() > target_size) {
2433 get_entries_from_global_stack();
2434 drain_local_queue(partially);
2435 }
2436 }
2437 }
2438
2439 // SATB Queue has several assumptions on whether to call the par or
2440 // non-par versions of the methods. this is why some of the code is
2441 // replicated. We should really get rid of the single-threaded version
2442 // of the code to simplify things.
2443 void G1CMTask::drain_satb_buffers() {
2444 if (has_aborted()) return;
2445
2446 // We set this so that the regular clock knows that we're in the
2447 // middle of draining buffers and doesn't set the abort flag when it
2448 // notices that SATB buffers are available for draining. It'd be
2449 // very counter productive if it did that. :-)
2450 _draining_satb_buffers = true;
2451
2452 G1CMSATBBufferClosure satb_cl(this, _g1h);
2453 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
2454
2455 // This keeps claiming and applying the closure to completed buffers
2456 // until we run out of buffers or we need to abort.
2457 while (!has_aborted() &&
2458 satb_mq_set.apply_closure_to_completed_buffer(&satb_cl)) {
2459 regular_clock_call();
2460 }
2461
2462 _draining_satb_buffers = false;
2463
2464 assert(has_aborted() ||
2465 concurrent() ||
2466 satb_mq_set.completed_buffers_num() == 0, "invariant");
2467
2468 // again, this was a potentially expensive operation, decrease the
2469 // limits to get the regular clock call early
2470 decrease_limits();
2471 }
2472
2473 void G1CMTask::print_stats() {
2474 log_debug(gc, stats)("Marking Stats, task = %u, calls = %d",
2475 _worker_id, _calls);
2476 log_debug(gc, stats)(" Elapsed time = %1.2lfms, Termination time = %1.2lfms",
2477 _elapsed_time_ms, _termination_time_ms);
2478 log_debug(gc, stats)(" Step Times (cum): num = %d, avg = %1.2lfms, sd = %1.2lfms",
2479 _step_times_ms.num(), _step_times_ms.avg(),
2480 _step_times_ms.sd());
2481 log_debug(gc, stats)(" max = %1.2lfms, total = %1.2lfms",
2482 _step_times_ms.maximum(), _step_times_ms.sum());
2483 }
2484
2485 bool G1ConcurrentMark::try_stealing(uint worker_id, int* hash_seed, oop& obj) {
2486 return _task_queues->steal(worker_id, hash_seed, obj);
2487 }
2488
2489 /*****************************************************************************
2490
2491 The do_marking_step(time_target_ms, ...) method is the building
2492 block of the parallel marking framework. It can be called in parallel
2493 with other invocations of do_marking_step() on different tasks
2494 (but only one per task, obviously) and concurrently with the
2495 mutator threads, or during remark, hence it eliminates the need
2496 for two versions of the code. When called during remark, it will
2497 pick up from where the task left off during the concurrent marking
2498 phase. Interestingly, tasks are also claimable during evacuation
2499 pauses too, since do_marking_step() ensures that it aborts before
2500 it needs to yield.
2501
2502 The data structures that it uses to do marking work are the
2503 following:
2504
2505 (1) Marking Bitmap. If there are gray objects that appear only
2506 on the bitmap (this happens either when dealing with an overflow
2507 or when the initial marking phase has simply marked the roots
2508 and didn't push them on the stack), then tasks claim heap
2509 regions whose bitmap they then scan to find gray objects. A
2510 global finger indicates where the end of the last claimed region
2511 is. A local finger indicates how far into the region a task has
2512 scanned. The two fingers are used to determine how to gray an
2513 object (i.e. whether simply marking it is OK, as it will be
2514 visited by a task in the future, or whether it needs to be also
2515 pushed on a stack).
2516
2517 (2) Local Queue. The local queue of the task which is accessed
2518 reasonably efficiently by the task. Other tasks can steal from
2519 it when they run out of work. Throughout the marking phase, a
2520 task attempts to keep its local queue short but not totally
2521 empty, so that entries are available for stealing by other
2522 tasks. Only when there is no more work, a task will totally
2523 drain its local queue.
2524
2525 (3) Global Mark Stack. This handles local queue overflow. During
2526 marking only sets of entries are moved between it and the local
2527 queues, as access to it requires a mutex and more fine-grain
2528 interaction with it which might cause contention. If it
2529 overflows, then the marking phase should restart and iterate
2530 over the bitmap to identify gray objects. Throughout the marking
2531 phase, tasks attempt to keep the global mark stack at a small
2532 length but not totally empty, so that entries are available for
2533 popping by other tasks. Only when there is no more work, tasks
2534 will totally drain the global mark stack.
2535
2536 (4) SATB Buffer Queue. This is where completed SATB buffers are
2537 made available. Buffers are regularly removed from this queue
2538 and scanned for roots, so that the queue doesn't get too
2539 long. During remark, all completed buffers are processed, as
2540 well as the filled in parts of any uncompleted buffers.
2541
2542 The do_marking_step() method tries to abort when the time target
2543 has been reached. There are a few other cases when the
2544 do_marking_step() method also aborts:
2545
2546 (1) When the marking phase has been aborted (after a Full GC).
2547
2548 (2) When a global overflow (on the global stack) has been
2549 triggered. Before the task aborts, it will actually sync up with
2550 the other tasks to ensure that all the marking data structures
2551 (local queues, stacks, fingers etc.) are re-initialized so that
2552 when do_marking_step() completes, the marking phase can
2553 immediately restart.
2554
2555 (3) When enough completed SATB buffers are available. The
2556 do_marking_step() method only tries to drain SATB buffers right
2557 at the beginning. So, if enough buffers are available, the
2558 marking step aborts and the SATB buffers are processed at
2559 the beginning of the next invocation.
2560
2561 (4) To yield. when we have to yield then we abort and yield
2562 right at the end of do_marking_step(). This saves us from a lot
2563 of hassle as, by yielding we might allow a Full GC. If this
2564 happens then objects will be compacted underneath our feet, the
2565 heap might shrink, etc. We save checking for this by just
2566 aborting and doing the yield right at the end.
2567
2568 From the above it follows that the do_marking_step() method should
2569 be called in a loop (or, otherwise, regularly) until it completes.
2570
2571 If a marking step completes without its has_aborted() flag being
2572 true, it means it has completed the current marking phase (and
2573 also all other marking tasks have done so and have all synced up).
2574
2575 A method called regular_clock_call() is invoked "regularly" (in
2576 sub ms intervals) throughout marking. It is this clock method that
2577 checks all the abort conditions which were mentioned above and
2578 decides when the task should abort. A work-based scheme is used to
2579 trigger this clock method: when the number of object words the
2580 marking phase has scanned or the number of references the marking
2581 phase has visited reach a given limit. Additional invocations to
2582 the method clock have been planted in a few other strategic places
2583 too. The initial reason for the clock method was to avoid calling
2584 vtime too regularly, as it is quite expensive. So, once it was in
2585 place, it was natural to piggy-back all the other conditions on it
2586 too and not constantly check them throughout the code.
2587
2588 If do_termination is true then do_marking_step will enter its
2589 termination protocol.
2590
2591 The value of is_serial must be true when do_marking_step is being
2592 called serially (i.e. by the VMThread) and do_marking_step should
2593 skip any synchronization in the termination and overflow code.
2594 Examples include the serial remark code and the serial reference
2595 processing closures.
2596
2597 The value of is_serial must be false when do_marking_step is
2598 being called by any of the worker threads in a work gang.
2599 Examples include the concurrent marking code (CMMarkingTask),
2600 the MT remark code, and the MT reference processing closures.
2601
2602 *****************************************************************************/
2603
2604 void G1CMTask::do_marking_step(double time_target_ms,
2605 bool do_termination,
2606 bool is_serial) {
2607 assert(time_target_ms >= 1.0, "minimum granularity is 1ms");
2608 assert(concurrent() == _cm->concurrent(), "they should be the same");
2609
2610 G1Policy* g1_policy = _g1h->g1_policy();
2611 assert(_task_queues != NULL, "invariant");
2612 assert(_task_queue != NULL, "invariant");
2613 assert(_task_queues->queue(_worker_id) == _task_queue, "invariant");
2614
2615 assert(!_claimed,
2616 "only one thread should claim this task at any one time");
2617
2618 // OK, this doesn't safeguard again all possible scenarios, as it is
2619 // possible for two threads to set the _claimed flag at the same
2620 // time. But it is only for debugging purposes anyway and it will
2621 // catch most problems.
2622 _claimed = true;
2623
2624 _start_time_ms = os::elapsedVTime() * 1000.0;
2625
2626 // If do_stealing is true then do_marking_step will attempt to
2627 // steal work from the other G1CMTasks. It only makes sense to
2628 // enable stealing when the termination protocol is enabled
2629 // and do_marking_step() is not being called serially.
2630 bool do_stealing = do_termination && !is_serial;
2631
2632 double diff_prediction_ms = _g1h->g1_policy()->predictor().get_new_prediction(&_marking_step_diffs_ms);
2633 _time_target_ms = time_target_ms - diff_prediction_ms;
2634
2635 // set up the variables that are used in the work-based scheme to
2636 // call the regular clock method
2637 _words_scanned = 0;
2638 _refs_reached = 0;
2639 recalculate_limits();
2640
2641 // clear all flags
2642 clear_has_aborted();
2643 _has_timed_out = false;
2644 _draining_satb_buffers = false;
2645
2646 ++_calls;
2647
2648 // Set up the bitmap and oop closures. Anything that uses them is
2649 // eventually called from this method, so it is OK to allocate these
2650 // statically.
2651 G1CMBitMapClosure bitmap_closure(this, _cm, _nextMarkBitMap);
2652 G1CMOopClosure cm_oop_closure(_g1h, _cm, this);
2653 set_cm_oop_closure(&cm_oop_closure);
2654
2655 if (_cm->has_overflown()) {
2656 // This can happen if the mark stack overflows during a GC pause
2657 // and this task, after a yield point, restarts. We have to abort
2658 // as we need to get into the overflow protocol which happens
2659 // right at the end of this task.
2660 set_has_aborted();
2661 }
2662
2663 // First drain any available SATB buffers. After this, we will not
2664 // look at SATB buffers before the next invocation of this method.
2665 // If enough completed SATB buffers are queued up, the regular clock
2666 // will abort this task so that it restarts.
2667 drain_satb_buffers();
2668 // ...then partially drain the local queue and the global stack
2669 drain_local_queue(true);
2670 drain_global_stack(true);
2671
2672 do {
2673 if (!has_aborted() && _curr_region != NULL) {
2674 // This means that we're already holding on to a region.
2675 assert(_finger != NULL, "if region is not NULL, then the finger "
2676 "should not be NULL either");
2677
2678 // We might have restarted this task after an evacuation pause
2679 // which might have evacuated the region we're holding on to
2680 // underneath our feet. Let's read its limit again to make sure
2681 // that we do not iterate over a region of the heap that
2682 // contains garbage (update_region_limit() will also move
2683 // _finger to the start of the region if it is found empty).
2684 update_region_limit();
2685 // We will start from _finger not from the start of the region,
2686 // as we might be restarting this task after aborting half-way
2687 // through scanning this region. In this case, _finger points to
2688 // the address where we last found a marked object. If this is a
2689 // fresh region, _finger points to start().
2690 MemRegion mr = MemRegion(_finger, _region_limit);
2691
2692 assert(!_curr_region->is_humongous() || mr.start() == _curr_region->bottom(),
2693 "humongous regions should go around loop once only");
2694
2695 // Some special cases:
2696 // If the memory region is empty, we can just give up the region.
2697 // If the current region is humongous then we only need to check
2698 // the bitmap for the bit associated with the start of the object,
2699 // scan the object if it's live, and give up the region.
2700 // Otherwise, let's iterate over the bitmap of the part of the region
2701 // that is left.
2702 // If the iteration is successful, give up the region.
2703 if (mr.is_empty()) {
2704 giveup_current_region();
2705 regular_clock_call();
2706 } else if (_curr_region->is_humongous() && mr.start() == _curr_region->bottom()) {
2707 if (_nextMarkBitMap->isMarked(mr.start())) {
2708 // The object is marked - apply the closure
2709 BitMap::idx_t offset = _nextMarkBitMap->heapWordToOffset(mr.start());
2710 bitmap_closure.do_bit(offset);
2711 }
2712 // Even if this task aborted while scanning the humongous object
2713 // we can (and should) give up the current region.
2714 giveup_current_region();
2715 regular_clock_call();
2716 } else if (_nextMarkBitMap->iterate(&bitmap_closure, mr)) {
2717 giveup_current_region();
2718 regular_clock_call();
2719 } else {
2720 assert(has_aborted(), "currently the only way to do so");
2721 // The only way to abort the bitmap iteration is to return
2722 // false from the do_bit() method. However, inside the
2723 // do_bit() method we move the _finger to point to the
2724 // object currently being looked at. So, if we bail out, we
2725 // have definitely set _finger to something non-null.
2726 assert(_finger != NULL, "invariant");
2727
2728 // Region iteration was actually aborted. So now _finger
2729 // points to the address of the object we last scanned. If we
2730 // leave it there, when we restart this task, we will rescan
2731 // the object. It is easy to avoid this. We move the finger by
2732 // enough to point to the next possible object header (the
2733 // bitmap knows by how much we need to move it as it knows its
2734 // granularity).
2735 assert(_finger < _region_limit, "invariant");
2736 HeapWord* new_finger = _nextMarkBitMap->nextObject(_finger);
2737 // Check if bitmap iteration was aborted while scanning the last object
2738 if (new_finger >= _region_limit) {
2739 giveup_current_region();
2740 } else {
2741 move_finger_to(new_finger);
2742 }
2743 }
2744 }
2745 // At this point we have either completed iterating over the
2746 // region we were holding on to, or we have aborted.
2747
2748 // We then partially drain the local queue and the global stack.
2749 // (Do we really need this?)
2750 drain_local_queue(true);
2751 drain_global_stack(true);
2752
2753 // Read the note on the claim_region() method on why it might
2754 // return NULL with potentially more regions available for
2755 // claiming and why we have to check out_of_regions() to determine
2756 // whether we're done or not.
2757 while (!has_aborted() && _curr_region == NULL && !_cm->out_of_regions()) {
2758 // We are going to try to claim a new region. We should have
2759 // given up on the previous one.
2760 // Separated the asserts so that we know which one fires.
2761 assert(_curr_region == NULL, "invariant");
2762 assert(_finger == NULL, "invariant");
2763 assert(_region_limit == NULL, "invariant");
2764 HeapRegion* claimed_region = _cm->claim_region(_worker_id);
2765 if (claimed_region != NULL) {
2766 // Yes, we managed to claim one
2767 setup_for_region(claimed_region);
2768 assert(_curr_region == claimed_region, "invariant");
2769 }
2770 // It is important to call the regular clock here. It might take
2771 // a while to claim a region if, for example, we hit a large
2772 // block of empty regions. So we need to call the regular clock
2773 // method once round the loop to make sure it's called
2774 // frequently enough.
2775 regular_clock_call();
2776 }
2777
2778 if (!has_aborted() && _curr_region == NULL) {
2779 assert(_cm->out_of_regions(),
2780 "at this point we should be out of regions");
2781 }
2782 } while ( _curr_region != NULL && !has_aborted());
2783
2784 if (!has_aborted()) {
2785 // We cannot check whether the global stack is empty, since other
2786 // tasks might be pushing objects to it concurrently.
2787 assert(_cm->out_of_regions(),
2788 "at this point we should be out of regions");
2789 // Try to reduce the number of available SATB buffers so that
2790 // remark has less work to do.
2791 drain_satb_buffers();
2792 }
2793
2794 // Since we've done everything else, we can now totally drain the
2795 // local queue and global stack.
2796 drain_local_queue(false);
2797 drain_global_stack(false);
2798
2799 // Attempt at work stealing from other task's queues.
2800 if (do_stealing && !has_aborted()) {
2801 // We have not aborted. This means that we have finished all that
2802 // we could. Let's try to do some stealing...
2803
2804 // We cannot check whether the global stack is empty, since other
2805 // tasks might be pushing objects to it concurrently.
2806 assert(_cm->out_of_regions() && _task_queue->size() == 0,
2807 "only way to reach here");
2808 while (!has_aborted()) {
2809 oop obj;
2810 if (_cm->try_stealing(_worker_id, &_hash_seed, obj)) {
2811 assert(_nextMarkBitMap->isMarked((HeapWord*) obj),
2812 "any stolen object should be marked");
2813 scan_object(obj);
2814
2815 // And since we're towards the end, let's totally drain the
2816 // local queue and global stack.
2817 drain_local_queue(false);
2818 drain_global_stack(false);
2819 } else {
2820 break;
2821 }
2822 }
2823 }
2824
2825 // We still haven't aborted. Now, let's try to get into the
2826 // termination protocol.
2827 if (do_termination && !has_aborted()) {
2828 // We cannot check whether the global stack is empty, since other
2829 // tasks might be concurrently pushing objects on it.
2830 // Separated the asserts so that we know which one fires.
2831 assert(_cm->out_of_regions(), "only way to reach here");
2832 assert(_task_queue->size() == 0, "only way to reach here");
2833 _termination_start_time_ms = os::elapsedVTime() * 1000.0;
2834
2835 // The G1CMTask class also extends the TerminatorTerminator class,
2836 // hence its should_exit_termination() method will also decide
2837 // whether to exit the termination protocol or not.
2838 bool finished = (is_serial ||
2839 _cm->terminator()->offer_termination(this));
2840 double termination_end_time_ms = os::elapsedVTime() * 1000.0;
2841 _termination_time_ms +=
2842 termination_end_time_ms - _termination_start_time_ms;
2843
2844 if (finished) {
2845 // We're all done.
2846
2847 if (_worker_id == 0) {
2848 // let's allow task 0 to do this
2849 if (concurrent()) {
2850 assert(_cm->concurrent_marking_in_progress(), "invariant");
2851 // we need to set this to false before the next
2852 // safepoint. This way we ensure that the marking phase
2853 // doesn't observe any more heap expansions.
2854 _cm->clear_concurrent_marking_in_progress();
2855 }
2856 }
2857
2858 // We can now guarantee that the global stack is empty, since
2859 // all other tasks have finished. We separated the guarantees so
2860 // that, if a condition is false, we can immediately find out
2861 // which one.
2862 guarantee(_cm->out_of_regions(), "only way to reach here");
2863 guarantee(_cm->mark_stack_empty(), "only way to reach here");
2864 guarantee(_task_queue->size() == 0, "only way to reach here");
2865 guarantee(!_cm->has_overflown(), "only way to reach here");
2866 guarantee(!_cm->mark_stack_overflow(), "only way to reach here");
2867 } else {
2868 // Apparently there's more work to do. Let's abort this task. It
2869 // will restart it and we can hopefully find more things to do.
2870 set_has_aborted();
2871 }
2872 }
2873
2874 // Mainly for debugging purposes to make sure that a pointer to the
2875 // closure which was statically allocated in this frame doesn't
2876 // escape it by accident.
2877 set_cm_oop_closure(NULL);
2878 double end_time_ms = os::elapsedVTime() * 1000.0;
2879 double elapsed_time_ms = end_time_ms - _start_time_ms;
2880 // Update the step history.
2881 _step_times_ms.add(elapsed_time_ms);
2882
2883 if (has_aborted()) {
2884 // The task was aborted for some reason.
2885 if (_has_timed_out) {
2886 double diff_ms = elapsed_time_ms - _time_target_ms;
2887 // Keep statistics of how well we did with respect to hitting
2888 // our target only if we actually timed out (if we aborted for
2889 // other reasons, then the results might get skewed).
2890 _marking_step_diffs_ms.add(diff_ms);
2891 }
2892
2893 if (_cm->has_overflown()) {
2894 // This is the interesting one. We aborted because a global
2895 // overflow was raised. This means we have to restart the
2896 // marking phase and start iterating over regions. However, in
2897 // order to do this we have to make sure that all tasks stop
2898 // what they are doing and re-initialize in a safe manner. We
2899 // will achieve this with the use of two barrier sync points.
2900
2901 if (!is_serial) {
2902 // We only need to enter the sync barrier if being called
2903 // from a parallel context
2904 _cm->enter_first_sync_barrier(_worker_id);
2905
2906 // When we exit this sync barrier we know that all tasks have
2907 // stopped doing marking work. So, it's now safe to
2908 // re-initialize our data structures. At the end of this method,
2909 // task 0 will clear the global data structures.
2910 }
2911
2912 // We clear the local state of this task...
2913 clear_region_fields();
2914
2915 if (!is_serial) {
2916 // ...and enter the second barrier.
2917 _cm->enter_second_sync_barrier(_worker_id);
2918 }
2919 // At this point, if we're during the concurrent phase of
2920 // marking, everything has been re-initialized and we're
2921 // ready to restart.
2922 }
2923 }
2924
2925 _claimed = false;
2926 }
2927
2928 G1CMTask::G1CMTask(uint worker_id,
2929 G1ConcurrentMark* cm,
2930 G1CMTaskQueue* task_queue,
2931 G1CMTaskQueueSet* task_queues)
2932 : _g1h(G1CollectedHeap::heap()),
2933 _worker_id(worker_id), _cm(cm),
2934 _claimed(false),
2935 _nextMarkBitMap(NULL), _hash_seed(17),
2936 _task_queue(task_queue),
2937 _task_queues(task_queues),
2938 _cm_oop_closure(NULL) {
2939 guarantee(task_queue != NULL, "invariant");
2940 guarantee(task_queues != NULL, "invariant");
2941
2942 _marking_step_diffs_ms.add(0.5);
2943 }
2944
2945 // These are formatting macros that are used below to ensure
2946 // consistent formatting. The *_H_* versions are used to format the
2947 // header for a particular value and they should be kept consistent
2948 // with the corresponding macro. Also note that most of the macros add
2949 // the necessary white space (as a prefix) which makes them a bit
2950 // easier to compose.
2951
2952 // All the output lines are prefixed with this string to be able to
2953 // identify them easily in a large log file.
2954 #define G1PPRL_LINE_PREFIX "###"
2955
2956 #define G1PPRL_ADDR_BASE_FORMAT " " PTR_FORMAT "-" PTR_FORMAT
2957 #ifdef _LP64
2958 #define G1PPRL_ADDR_BASE_H_FORMAT " %37s"
2959 #else // _LP64
2960 #define G1PPRL_ADDR_BASE_H_FORMAT " %21s"
2961 #endif // _LP64
2962
2963 // For per-region info
2964 #define G1PPRL_TYPE_FORMAT " %-4s"
2965 #define G1PPRL_TYPE_H_FORMAT " %4s"
2966 #define G1PPRL_BYTE_FORMAT " " SIZE_FORMAT_W(9)
2967 #define G1PPRL_BYTE_H_FORMAT " %9s"
2968 #define G1PPRL_DOUBLE_FORMAT " %14.1f"
2969 #define G1PPRL_DOUBLE_H_FORMAT " %14s"
2970
2971 // For summary info
2972 #define G1PPRL_SUM_ADDR_FORMAT(tag) " " tag ":" G1PPRL_ADDR_BASE_FORMAT
2973 #define G1PPRL_SUM_BYTE_FORMAT(tag) " " tag ": " SIZE_FORMAT
2974 #define G1PPRL_SUM_MB_FORMAT(tag) " " tag ": %1.2f MB"
2975 #define G1PPRL_SUM_MB_PERC_FORMAT(tag) G1PPRL_SUM_MB_FORMAT(tag) " / %1.2f %%"
2976
2977 G1PrintRegionLivenessInfoClosure::
2978 G1PrintRegionLivenessInfoClosure(const char* phase_name)
2979 : _total_used_bytes(0), _total_capacity_bytes(0),
2980 _total_prev_live_bytes(0), _total_next_live_bytes(0),
2981 _total_remset_bytes(0), _total_strong_code_roots_bytes(0) {
2982 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2983 MemRegion g1_reserved = g1h->g1_reserved();
2984 double now = os::elapsedTime();
2985
2986 // Print the header of the output.
2987 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX" PHASE %s @ %1.3f", phase_name, now);
2988 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX" HEAP"
2989 G1PPRL_SUM_ADDR_FORMAT("reserved")
2990 G1PPRL_SUM_BYTE_FORMAT("region-size"),
2991 p2i(g1_reserved.start()), p2i(g1_reserved.end()),
2992 HeapRegion::GrainBytes);
2993 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX);
2994 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX
2995 G1PPRL_TYPE_H_FORMAT
2996 G1PPRL_ADDR_BASE_H_FORMAT
2997 G1PPRL_BYTE_H_FORMAT
2998 G1PPRL_BYTE_H_FORMAT
2999 G1PPRL_BYTE_H_FORMAT
3000 G1PPRL_DOUBLE_H_FORMAT
3001 G1PPRL_BYTE_H_FORMAT
3002 G1PPRL_BYTE_H_FORMAT,
3003 "type", "address-range",
3004 "used", "prev-live", "next-live", "gc-eff",
3005 "remset", "code-roots");
3006 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX
3007 G1PPRL_TYPE_H_FORMAT
3008 G1PPRL_ADDR_BASE_H_FORMAT
3009 G1PPRL_BYTE_H_FORMAT
3010 G1PPRL_BYTE_H_FORMAT
3011 G1PPRL_BYTE_H_FORMAT
3012 G1PPRL_DOUBLE_H_FORMAT
3013 G1PPRL_BYTE_H_FORMAT
3014 G1PPRL_BYTE_H_FORMAT,
3015 "", "",
3016 "(bytes)", "(bytes)", "(bytes)", "(bytes/ms)",
3017 "(bytes)", "(bytes)");
3018 }
3019
3020 bool G1PrintRegionLivenessInfoClosure::doHeapRegion(HeapRegion* r) {
3021 const char* type = r->get_type_str();
3022 HeapWord* bottom = r->bottom();
3023 HeapWord* end = r->end();
3024 size_t capacity_bytes = r->capacity();
3025 size_t used_bytes = r->used();
3026 size_t prev_live_bytes = r->live_bytes();
3027 size_t next_live_bytes = r->next_live_bytes();
3028 double gc_eff = r->gc_efficiency();
3029 size_t remset_bytes = r->rem_set()->mem_size();
3030 size_t strong_code_roots_bytes = r->rem_set()->strong_code_roots_mem_size();
3031
3032 _total_used_bytes += used_bytes;
3033 _total_capacity_bytes += capacity_bytes;
3034 _total_prev_live_bytes += prev_live_bytes;
3035 _total_next_live_bytes += next_live_bytes;
3036 _total_remset_bytes += remset_bytes;
3037 _total_strong_code_roots_bytes += strong_code_roots_bytes;
3038
3039 // Print a line for this particular region.
3040 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX
3041 G1PPRL_TYPE_FORMAT
3042 G1PPRL_ADDR_BASE_FORMAT
3043 G1PPRL_BYTE_FORMAT
3044 G1PPRL_BYTE_FORMAT
3045 G1PPRL_BYTE_FORMAT
3046 G1PPRL_DOUBLE_FORMAT
3047 G1PPRL_BYTE_FORMAT
3048 G1PPRL_BYTE_FORMAT,
3049 type, p2i(bottom), p2i(end),
3050 used_bytes, prev_live_bytes, next_live_bytes, gc_eff,
3051 remset_bytes, strong_code_roots_bytes);
3052
3053 return false;
3054 }
3055
3056 G1PrintRegionLivenessInfoClosure::~G1PrintRegionLivenessInfoClosure() {
3057 // add static memory usages to remembered set sizes
3058 _total_remset_bytes += HeapRegionRemSet::fl_mem_size() + HeapRegionRemSet::static_mem_size();
3059 // Print the footer of the output.
3060 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX);
3061 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX
3062 " SUMMARY"
3063 G1PPRL_SUM_MB_FORMAT("capacity")
3064 G1PPRL_SUM_MB_PERC_FORMAT("used")
3065 G1PPRL_SUM_MB_PERC_FORMAT("prev-live")
3066 G1PPRL_SUM_MB_PERC_FORMAT("next-live")
3067 G1PPRL_SUM_MB_FORMAT("remset")
3068 G1PPRL_SUM_MB_FORMAT("code-roots"),
3069 bytes_to_mb(_total_capacity_bytes),
3070 bytes_to_mb(_total_used_bytes),
3071 perc(_total_used_bytes, _total_capacity_bytes),
3072 bytes_to_mb(_total_prev_live_bytes),
3073 perc(_total_prev_live_bytes, _total_capacity_bytes),
3074 bytes_to_mb(_total_next_live_bytes),
3075 perc(_total_next_live_bytes, _total_capacity_bytes),
3076 bytes_to_mb(_total_remset_bytes),
3077 bytes_to_mb(_total_strong_code_roots_bytes));
3078 }