1 /*
2 * Copyright (c) 2001, 2012, 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/symbolTable.hpp"
27 #include "gc_implementation/g1/concurrentMark.inline.hpp"
28 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
29 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
30 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
31 #include "gc_implementation/g1/g1ErgoVerbose.hpp"
32 #include "gc_implementation/g1/g1Log.hpp"
33 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
34 #include "gc_implementation/g1/g1RemSet.hpp"
35 #include "gc_implementation/g1/heapRegion.inline.hpp"
36 #include "gc_implementation/g1/heapRegionRemSet.hpp"
37 #include "gc_implementation/g1/heapRegionSeq.inline.hpp"
38 #include "gc_implementation/shared/vmGCOperations.hpp"
39 #include "memory/genOopClosures.inline.hpp"
40 #include "memory/referencePolicy.hpp"
41 #include "memory/resourceArea.hpp"
42 #include "oops/oop.inline.hpp"
43 #include "runtime/handles.inline.hpp"
44 #include "runtime/java.hpp"
45 #include "services/memTracker.hpp"
46
47 // Concurrent marking bit map wrapper
48
49 CMBitMapRO::CMBitMapRO(ReservedSpace rs, int shifter) :
50 _bm((uintptr_t*)NULL,0),
51 _shifter(shifter) {
52 _bmStartWord = (HeapWord*)(rs.base());
53 _bmWordSize = rs.size()/HeapWordSize; // rs.size() is in bytes
54 ReservedSpace brs(ReservedSpace::allocation_align_size_up(
55 (_bmWordSize >> (_shifter + LogBitsPerByte)) + 1));
56
57 MemTracker::record_virtual_memory_type((address)brs.base(), mtGC);
58
59 guarantee(brs.is_reserved(), "couldn't allocate concurrent marking bit map");
60 // For now we'll just commit all of the bit map up fromt.
61 // Later on we'll try to be more parsimonious with swap.
62 guarantee(_virtual_space.initialize(brs, brs.size()),
63 "couldn't reseve backing store for concurrent marking bit map");
64 assert(_virtual_space.committed_size() == brs.size(),
65 "didn't reserve backing store for all of concurrent marking bit map?");
66 _bm.set_map((uintptr_t*)_virtual_space.low());
67 assert(_virtual_space.committed_size() << (_shifter + LogBitsPerByte) >=
68 _bmWordSize, "inconsistency in bit map sizing");
69 _bm.set_size(_bmWordSize >> _shifter);
70 }
71
72 HeapWord* CMBitMapRO::getNextMarkedWordAddress(HeapWord* addr,
73 HeapWord* limit) const {
74 // First we must round addr *up* to a possible object boundary.
75 addr = (HeapWord*)align_size_up((intptr_t)addr,
76 HeapWordSize << _shifter);
77 size_t addrOffset = heapWordToOffset(addr);
78 if (limit == NULL) {
79 limit = _bmStartWord + _bmWordSize;
80 }
81 size_t limitOffset = heapWordToOffset(limit);
82 size_t nextOffset = _bm.get_next_one_offset(addrOffset, limitOffset);
83 HeapWord* nextAddr = offsetToHeapWord(nextOffset);
84 assert(nextAddr >= addr, "get_next_one postcondition");
85 assert(nextAddr == limit || isMarked(nextAddr),
86 "get_next_one postcondition");
87 return nextAddr;
88 }
89
90 HeapWord* CMBitMapRO::getNextUnmarkedWordAddress(HeapWord* addr,
91 HeapWord* limit) const {
92 size_t addrOffset = heapWordToOffset(addr);
93 if (limit == NULL) {
94 limit = _bmStartWord + _bmWordSize;
95 }
96 size_t limitOffset = heapWordToOffset(limit);
97 size_t nextOffset = _bm.get_next_zero_offset(addrOffset, limitOffset);
98 HeapWord* nextAddr = offsetToHeapWord(nextOffset);
99 assert(nextAddr >= addr, "get_next_one postcondition");
100 assert(nextAddr == limit || !isMarked(nextAddr),
101 "get_next_one postcondition");
102 return nextAddr;
103 }
104
105 int CMBitMapRO::heapWordDiffToOffsetDiff(size_t diff) const {
106 assert((diff & ((1 << _shifter) - 1)) == 0, "argument check");
107 return (int) (diff >> _shifter);
108 }
109
110 #ifndef PRODUCT
111 bool CMBitMapRO::covers(ReservedSpace rs) const {
112 // assert(_bm.map() == _virtual_space.low(), "map inconsistency");
113 assert(((size_t)_bm.size() * ((size_t)1 << _shifter)) == _bmWordSize,
114 "size inconsistency");
115 return _bmStartWord == (HeapWord*)(rs.base()) &&
116 _bmWordSize == rs.size()>>LogHeapWordSize;
117 }
118 #endif
119
120 void CMBitMap::clearAll() {
121 _bm.clear();
122 return;
123 }
124
125 void CMBitMap::markRange(MemRegion mr) {
126 mr.intersection(MemRegion(_bmStartWord, _bmWordSize));
127 assert(!mr.is_empty(), "unexpected empty region");
128 assert((offsetToHeapWord(heapWordToOffset(mr.end())) ==
129 ((HeapWord *) mr.end())),
130 "markRange memory region end is not card aligned");
131 // convert address range into offset range
132 _bm.at_put_range(heapWordToOffset(mr.start()),
133 heapWordToOffset(mr.end()), true);
134 }
135
136 void CMBitMap::clearRange(MemRegion mr) {
137 mr.intersection(MemRegion(_bmStartWord, _bmWordSize));
138 assert(!mr.is_empty(), "unexpected empty region");
139 // convert address range into offset range
140 _bm.at_put_range(heapWordToOffset(mr.start()),
141 heapWordToOffset(mr.end()), false);
142 }
143
144 MemRegion CMBitMap::getAndClearMarkedRegion(HeapWord* addr,
145 HeapWord* end_addr) {
146 HeapWord* start = getNextMarkedWordAddress(addr);
147 start = MIN2(start, end_addr);
148 HeapWord* end = getNextUnmarkedWordAddress(start);
149 end = MIN2(end, end_addr);
150 assert(start <= end, "Consistency check");
151 MemRegion mr(start, end);
152 if (!mr.is_empty()) {
153 clearRange(mr);
154 }
155 return mr;
156 }
157
158 CMMarkStack::CMMarkStack(ConcurrentMark* cm) :
159 _base(NULL), _cm(cm)
160 #ifdef ASSERT
161 , _drain_in_progress(false)
162 , _drain_in_progress_yields(false)
163 #endif
164 {}
165
166 void CMMarkStack::allocate(size_t size) {
167 _base = NEW_C_HEAP_ARRAY(oop, size, mtGC);
168 if (_base == NULL) {
169 vm_exit_during_initialization("Failed to allocate CM region mark stack");
170 }
171 _index = 0;
172 _capacity = (jint) size;
173 _saved_index = -1;
174 NOT_PRODUCT(_max_depth = 0);
175 }
176
177 CMMarkStack::~CMMarkStack() {
178 if (_base != NULL) {
179 FREE_C_HEAP_ARRAY(oop, _base, mtGC);
180 }
181 }
182
183 void CMMarkStack::par_push(oop ptr) {
184 while (true) {
185 if (isFull()) {
186 _overflow = true;
187 return;
188 }
189 // Otherwise...
190 jint index = _index;
191 jint next_index = index+1;
192 jint res = Atomic::cmpxchg(next_index, &_index, index);
193 if (res == index) {
194 _base[index] = ptr;
195 // Note that we don't maintain this atomically. We could, but it
196 // doesn't seem necessary.
197 NOT_PRODUCT(_max_depth = MAX2(_max_depth, next_index));
198 return;
199 }
200 // Otherwise, we need to try again.
201 }
202 }
203
204 void CMMarkStack::par_adjoin_arr(oop* ptr_arr, int n) {
205 while (true) {
206 if (isFull()) {
207 _overflow = true;
208 return;
209 }
210 // Otherwise...
211 jint index = _index;
212 jint next_index = index + n;
213 if (next_index > _capacity) {
214 _overflow = true;
215 return;
216 }
217 jint res = Atomic::cmpxchg(next_index, &_index, index);
218 if (res == index) {
219 for (int i = 0; i < n; i++) {
220 int ind = index + i;
221 assert(ind < _capacity, "By overflow test above.");
222 _base[ind] = ptr_arr[i];
223 }
224 NOT_PRODUCT(_max_depth = MAX2(_max_depth, next_index));
225 return;
226 }
227 // Otherwise, we need to try again.
228 }
229 }
230
231
232 void CMMarkStack::par_push_arr(oop* ptr_arr, int n) {
233 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
234 jint start = _index;
235 jint next_index = start + n;
236 if (next_index > _capacity) {
237 _overflow = true;
238 return;
239 }
240 // Otherwise.
241 _index = next_index;
242 for (int i = 0; i < n; i++) {
243 int ind = start + i;
244 assert(ind < _capacity, "By overflow test above.");
245 _base[ind] = ptr_arr[i];
246 }
247 }
248
249
250 bool CMMarkStack::par_pop_arr(oop* ptr_arr, int max, int* n) {
251 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
252 jint index = _index;
253 if (index == 0) {
254 *n = 0;
255 return false;
256 } else {
257 int k = MIN2(max, index);
258 jint new_ind = index - k;
259 for (int j = 0; j < k; j++) {
260 ptr_arr[j] = _base[new_ind + j];
261 }
262 _index = new_ind;
263 *n = k;
264 return true;
265 }
266 }
267
268 template<class OopClosureClass>
269 bool CMMarkStack::drain(OopClosureClass* cl, CMBitMap* bm, bool yield_after) {
270 assert(!_drain_in_progress || !_drain_in_progress_yields || yield_after
271 || SafepointSynchronize::is_at_safepoint(),
272 "Drain recursion must be yield-safe.");
273 bool res = true;
274 debug_only(_drain_in_progress = true);
275 debug_only(_drain_in_progress_yields = yield_after);
276 while (!isEmpty()) {
277 oop newOop = pop();
278 assert(G1CollectedHeap::heap()->is_in_reserved(newOop), "Bad pop");
279 assert(newOop->is_oop(), "Expected an oop");
280 assert(bm == NULL || bm->isMarked((HeapWord*)newOop),
281 "only grey objects on this stack");
282 newOop->oop_iterate(cl);
283 if (yield_after && _cm->do_yield_check()) {
284 res = false;
285 break;
286 }
287 }
288 debug_only(_drain_in_progress = false);
289 return res;
290 }
291
292 void CMMarkStack::note_start_of_gc() {
293 assert(_saved_index == -1,
294 "note_start_of_gc()/end_of_gc() bracketed incorrectly");
295 _saved_index = _index;
296 }
297
298 void CMMarkStack::note_end_of_gc() {
299 // This is intentionally a guarantee, instead of an assert. If we
300 // accidentally add something to the mark stack during GC, it
301 // will be a correctness issue so it's better if we crash. we'll
302 // only check this once per GC anyway, so it won't be a performance
303 // issue in any way.
304 guarantee(_saved_index == _index,
305 err_msg("saved index: %d index: %d", _saved_index, _index));
306 _saved_index = -1;
307 }
308
309 void CMMarkStack::oops_do(OopClosure* f) {
310 assert(_saved_index == _index,
311 err_msg("saved index: %d index: %d", _saved_index, _index));
312 for (int i = 0; i < _index; i += 1) {
313 f->do_oop(&_base[i]);
314 }
315 }
316
317 bool ConcurrentMark::not_yet_marked(oop obj) const {
318 return _g1h->is_obj_ill(obj);
319 }
320
321 CMRootRegions::CMRootRegions() :
322 _young_list(NULL), _cm(NULL), _scan_in_progress(false),
323 _should_abort(false), _next_survivor(NULL) { }
324
325 void CMRootRegions::init(G1CollectedHeap* g1h, ConcurrentMark* cm) {
326 _young_list = g1h->young_list();
327 _cm = cm;
328 }
329
330 void CMRootRegions::prepare_for_scan() {
331 assert(!scan_in_progress(), "pre-condition");
332
333 // Currently, only survivors can be root regions.
334 assert(_next_survivor == NULL, "pre-condition");
335 _next_survivor = _young_list->first_survivor_region();
336 _scan_in_progress = (_next_survivor != NULL);
337 _should_abort = false;
338 }
339
340 HeapRegion* CMRootRegions::claim_next() {
341 if (_should_abort) {
342 // If someone has set the should_abort flag, we return NULL to
343 // force the caller to bail out of their loop.
344 return NULL;
345 }
346
347 // Currently, only survivors can be root regions.
348 HeapRegion* res = _next_survivor;
349 if (res != NULL) {
350 MutexLockerEx x(RootRegionScan_lock, Mutex::_no_safepoint_check_flag);
351 // Read it again in case it changed while we were waiting for the lock.
352 res = _next_survivor;
353 if (res != NULL) {
354 if (res == _young_list->last_survivor_region()) {
355 // We just claimed the last survivor so store NULL to indicate
356 // that we're done.
357 _next_survivor = NULL;
358 } else {
359 _next_survivor = res->get_next_young_region();
360 }
361 } else {
362 // Someone else claimed the last survivor while we were trying
363 // to take the lock so nothing else to do.
364 }
365 }
366 assert(res == NULL || res->is_survivor(), "post-condition");
367
368 return res;
369 }
370
371 void CMRootRegions::scan_finished() {
372 assert(scan_in_progress(), "pre-condition");
373
374 // Currently, only survivors can be root regions.
375 if (!_should_abort) {
376 assert(_next_survivor == NULL, "we should have claimed all survivors");
377 }
378 _next_survivor = NULL;
379
380 {
381 MutexLockerEx x(RootRegionScan_lock, Mutex::_no_safepoint_check_flag);
382 _scan_in_progress = false;
383 RootRegionScan_lock->notify_all();
384 }
385 }
386
387 bool CMRootRegions::wait_until_scan_finished() {
388 if (!scan_in_progress()) return false;
389
390 {
391 MutexLockerEx x(RootRegionScan_lock, Mutex::_no_safepoint_check_flag);
392 while (scan_in_progress()) {
393 RootRegionScan_lock->wait(Mutex::_no_safepoint_check_flag);
394 }
395 }
396 return true;
397 }
398
399 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
400 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
401 #endif // _MSC_VER
402
403 uint ConcurrentMark::scale_parallel_threads(uint n_par_threads) {
404 return MAX2((n_par_threads + 2) / 4, 1U);
405 }
406
407 ConcurrentMark::ConcurrentMark(ReservedSpace rs, uint max_regions) :
408 _markBitMap1(rs, MinObjAlignment - 1),
409 _markBitMap2(rs, MinObjAlignment - 1),
410
411 _parallel_marking_threads(0),
412 _max_parallel_marking_threads(0),
413 _sleep_factor(0.0),
414 _marking_task_overhead(1.0),
415 _cleanup_sleep_factor(0.0),
416 _cleanup_task_overhead(1.0),
417 _cleanup_list("Cleanup List"),
418 _region_bm((BitMap::idx_t) max_regions, false /* in_resource_area*/),
419 _card_bm((rs.size() + CardTableModRefBS::card_size - 1) >>
420 CardTableModRefBS::card_shift,
421 false /* in_resource_area*/),
422
423 _prevMarkBitMap(&_markBitMap1),
424 _nextMarkBitMap(&_markBitMap2),
425
426 _markStack(this),
427 // _finger set in set_non_marking_state
428
429 _max_task_num(MAX2((uint)ParallelGCThreads, 1U)),
430 // _active_tasks set in set_non_marking_state
431 // _tasks set inside the constructor
432 _task_queues(new CMTaskQueueSet((int) _max_task_num)),
433 _terminator(ParallelTaskTerminator((int) _max_task_num, _task_queues)),
434
435 _has_overflown(false),
436 _concurrent(false),
437 _has_aborted(false),
438 _restart_for_overflow(false),
439 _concurrent_marking_in_progress(false),
440
441 // _verbose_level set below
442
443 _init_times(),
444 _remark_times(), _remark_mark_times(), _remark_weak_ref_times(),
445 _cleanup_times(),
446 _total_counting_time(0.0),
447 _total_rs_scrub_time(0.0),
448
449 _parallel_workers(NULL),
450
451 _count_card_bitmaps(NULL),
452 _count_marked_bytes(NULL) {
453 CMVerboseLevel verbose_level = (CMVerboseLevel) G1MarkingVerboseLevel;
454 if (verbose_level < no_verbose) {
455 verbose_level = no_verbose;
456 }
457 if (verbose_level > high_verbose) {
458 verbose_level = high_verbose;
459 }
460 _verbose_level = verbose_level;
461
462 if (verbose_low()) {
463 gclog_or_tty->print_cr("[global] init, heap start = "PTR_FORMAT", "
464 "heap end = "PTR_FORMAT, _heap_start, _heap_end);
465 }
466
467 _markStack.allocate(MarkStackSize);
468
469 // Create & start a ConcurrentMark thread.
470 _cmThread = new ConcurrentMarkThread(this);
471 assert(cmThread() != NULL, "CM Thread should have been created");
472 assert(cmThread()->cm() != NULL, "CM Thread should refer to this cm");
473
474 _g1h = G1CollectedHeap::heap();
475 assert(CGC_lock != NULL, "Where's the CGC_lock?");
476 assert(_markBitMap1.covers(rs), "_markBitMap1 inconsistency");
477 assert(_markBitMap2.covers(rs), "_markBitMap2 inconsistency");
478
479 SATBMarkQueueSet& satb_qs = JavaThread::satb_mark_queue_set();
480 satb_qs.set_buffer_size(G1SATBBufferSize);
481
482 _root_regions.init(_g1h, this);
483
484 _tasks = NEW_C_HEAP_ARRAY(CMTask*, _max_task_num, mtGC);
485 _accum_task_vtime = NEW_C_HEAP_ARRAY(double, _max_task_num, mtGC);
486
487 _count_card_bitmaps = NEW_C_HEAP_ARRAY(BitMap, _max_task_num, mtGC);
488 _count_marked_bytes = NEW_C_HEAP_ARRAY(size_t*, _max_task_num, mtGC);
489
490 BitMap::idx_t card_bm_size = _card_bm.size();
491
492 // so that the assertion in MarkingTaskQueue::task_queue doesn't fail
493 _active_tasks = _max_task_num;
494 for (int i = 0; i < (int) _max_task_num; ++i) {
495 CMTaskQueue* task_queue = new CMTaskQueue();
496 task_queue->initialize();
497 _task_queues->register_queue(i, task_queue);
498
499 _count_card_bitmaps[i] = BitMap(card_bm_size, false);
500 _count_marked_bytes[i] = NEW_C_HEAP_ARRAY(size_t, (size_t) max_regions, mtGC);
501
502 _tasks[i] = new CMTask(i, this,
503 _count_marked_bytes[i],
504 &_count_card_bitmaps[i],
505 task_queue, _task_queues);
506
507 _accum_task_vtime[i] = 0.0;
508 }
509
510 // Calculate the card number for the bottom of the heap. Used
511 // in biasing indexes into the accounting card bitmaps.
512 _heap_bottom_card_num =
513 intptr_t(uintptr_t(_g1h->reserved_region().start()) >>
514 CardTableModRefBS::card_shift);
515
516 // Clear all the liveness counting data
517 clear_all_count_data();
518
519 if (ConcGCThreads > ParallelGCThreads) {
520 vm_exit_during_initialization("Can't have more ConcGCThreads "
521 "than ParallelGCThreads.");
522 }
523 if (ParallelGCThreads == 0) {
524 // if we are not running with any parallel GC threads we will not
525 // spawn any marking threads either
526 _parallel_marking_threads = 0;
527 _max_parallel_marking_threads = 0;
528 _sleep_factor = 0.0;
529 _marking_task_overhead = 1.0;
530 } else {
531 if (ConcGCThreads > 0) {
532 // notice that ConcGCThreads overwrites G1MarkingOverheadPercent
533 // if both are set
534
535 _parallel_marking_threads = (uint) ConcGCThreads;
536 _max_parallel_marking_threads = _parallel_marking_threads;
537 _sleep_factor = 0.0;
538 _marking_task_overhead = 1.0;
539 } else if (G1MarkingOverheadPercent > 0) {
540 // we will calculate the number of parallel marking threads
541 // based on a target overhead with respect to the soft real-time
542 // goal
543
544 double marking_overhead = (double) G1MarkingOverheadPercent / 100.0;
545 double overall_cm_overhead =
546 (double) MaxGCPauseMillis * marking_overhead /
547 (double) GCPauseIntervalMillis;
548 double cpu_ratio = 1.0 / (double) os::processor_count();
549 double marking_thread_num = ceil(overall_cm_overhead / cpu_ratio);
550 double marking_task_overhead =
551 overall_cm_overhead / marking_thread_num *
552 (double) os::processor_count();
553 double sleep_factor =
554 (1.0 - marking_task_overhead) / marking_task_overhead;
555
556 _parallel_marking_threads = (uint) marking_thread_num;
557 _max_parallel_marking_threads = _parallel_marking_threads;
558 _sleep_factor = sleep_factor;
559 _marking_task_overhead = marking_task_overhead;
560 } else {
561 _parallel_marking_threads = scale_parallel_threads((uint)ParallelGCThreads);
562 _max_parallel_marking_threads = _parallel_marking_threads;
563 _sleep_factor = 0.0;
564 _marking_task_overhead = 1.0;
565 }
566
567 if (parallel_marking_threads() > 1) {
568 _cleanup_task_overhead = 1.0;
569 } else {
570 _cleanup_task_overhead = marking_task_overhead();
571 }
572 _cleanup_sleep_factor =
573 (1.0 - cleanup_task_overhead()) / cleanup_task_overhead();
574
575 #if 0
576 gclog_or_tty->print_cr("Marking Threads %d", parallel_marking_threads());
577 gclog_or_tty->print_cr("CM Marking Task Overhead %1.4lf", marking_task_overhead());
578 gclog_or_tty->print_cr("CM Sleep Factor %1.4lf", sleep_factor());
579 gclog_or_tty->print_cr("CL Marking Task Overhead %1.4lf", cleanup_task_overhead());
580 gclog_or_tty->print_cr("CL Sleep Factor %1.4lf", cleanup_sleep_factor());
581 #endif
582
583 guarantee(parallel_marking_threads() > 0, "peace of mind");
584 _parallel_workers = new FlexibleWorkGang("G1 Parallel Marking Threads",
585 _max_parallel_marking_threads, false, true);
586 if (_parallel_workers == NULL) {
587 vm_exit_during_initialization("Failed necessary allocation.");
588 } else {
589 _parallel_workers->initialize_workers();
590 }
591 }
592
593 // so that the call below can read a sensible value
594 _heap_start = (HeapWord*) rs.base();
595 set_non_marking_state();
596 }
597
598 void ConcurrentMark::update_g1_committed(bool force) {
599 // If concurrent marking is not in progress, then we do not need to
600 // update _heap_end.
601 if (!concurrent_marking_in_progress() && !force) return;
602
603 MemRegion committed = _g1h->g1_committed();
604 assert(committed.start() == _heap_start, "start shouldn't change");
605 HeapWord* new_end = committed.end();
606 if (new_end > _heap_end) {
607 // The heap has been expanded.
608
609 _heap_end = new_end;
610 }
611 // Notice that the heap can also shrink. However, this only happens
612 // during a Full GC (at least currently) and the entire marking
613 // phase will bail out and the task will not be restarted. So, let's
614 // do nothing.
615 }
616
617 void ConcurrentMark::reset() {
618 // Starting values for these two. This should be called in a STW
619 // phase. CM will be notified of any future g1_committed expansions
620 // will be at the end of evacuation pauses, when tasks are
621 // inactive.
622 MemRegion committed = _g1h->g1_committed();
623 _heap_start = committed.start();
624 _heap_end = committed.end();
625
626 // Separated the asserts so that we know which one fires.
627 assert(_heap_start != NULL, "heap bounds should look ok");
628 assert(_heap_end != NULL, "heap bounds should look ok");
629 assert(_heap_start < _heap_end, "heap bounds should look ok");
630
631 // reset all the marking data structures and any necessary flags
632 clear_marking_state();
633
634 if (verbose_low()) {
635 gclog_or_tty->print_cr("[global] resetting");
636 }
637
638 // We do reset all of them, since different phases will use
639 // different number of active threads. So, it's easiest to have all
640 // of them ready.
641 for (int i = 0; i < (int) _max_task_num; ++i) {
642 _tasks[i]->reset(_nextMarkBitMap);
643 }
644
645 // we need this to make sure that the flag is on during the evac
646 // pause with initial mark piggy-backed
647 set_concurrent_marking_in_progress();
648 }
649
650 void ConcurrentMark::set_phase(uint active_tasks, bool concurrent) {
651 assert(active_tasks <= _max_task_num, "we should not have more");
652
653 _active_tasks = active_tasks;
654 // Need to update the three data structures below according to the
655 // number of active threads for this phase.
656 _terminator = ParallelTaskTerminator((int) active_tasks, _task_queues);
657 _first_overflow_barrier_sync.set_n_workers((int) active_tasks);
658 _second_overflow_barrier_sync.set_n_workers((int) active_tasks);
659
660 _concurrent = concurrent;
661 // We propagate this to all tasks, not just the active ones.
662 for (int i = 0; i < (int) _max_task_num; ++i)
663 _tasks[i]->set_concurrent(concurrent);
664
665 if (concurrent) {
666 set_concurrent_marking_in_progress();
667 } else {
668 // We currently assume that the concurrent flag has been set to
669 // false before we start remark. At this point we should also be
670 // in a STW phase.
671 assert(!concurrent_marking_in_progress(), "invariant");
672 assert(_finger == _heap_end, "only way to get here");
673 update_g1_committed(true);
674 }
675 }
676
677 void ConcurrentMark::set_non_marking_state() {
678 // We set the global marking state to some default values when we're
679 // not doing marking.
680 clear_marking_state();
681 _active_tasks = 0;
682 clear_concurrent_marking_in_progress();
683 }
684
685 ConcurrentMark::~ConcurrentMark() {
686 // The ConcurrentMark instance is never freed.
687 ShouldNotReachHere();
688 }
689
690 void ConcurrentMark::clearNextBitmap() {
691 G1CollectedHeap* g1h = G1CollectedHeap::heap();
692 G1CollectorPolicy* g1p = g1h->g1_policy();
693
694 // Make sure that the concurrent mark thread looks to still be in
695 // the current cycle.
696 guarantee(cmThread()->during_cycle(), "invariant");
697
698 // We are finishing up the current cycle by clearing the next
699 // marking bitmap and getting it ready for the next cycle. During
700 // this time no other cycle can start. So, let's make sure that this
701 // is the case.
702 guarantee(!g1h->mark_in_progress(), "invariant");
703
704 // clear the mark bitmap (no grey objects to start with).
705 // We need to do this in chunks and offer to yield in between
706 // each chunk.
707 HeapWord* start = _nextMarkBitMap->startWord();
708 HeapWord* end = _nextMarkBitMap->endWord();
709 HeapWord* cur = start;
710 size_t chunkSize = M;
711 while (cur < end) {
712 HeapWord* next = cur + chunkSize;
713 if (next > end) {
714 next = end;
715 }
716 MemRegion mr(cur,next);
717 _nextMarkBitMap->clearRange(mr);
718 cur = next;
719 do_yield_check();
720
721 // Repeat the asserts from above. We'll do them as asserts here to
722 // minimize their overhead on the product. However, we'll have
723 // them as guarantees at the beginning / end of the bitmap
724 // clearing to get some checking in the product.
725 assert(cmThread()->during_cycle(), "invariant");
726 assert(!g1h->mark_in_progress(), "invariant");
727 }
728
729 // Clear the liveness counting data
730 clear_all_count_data();
731
732 // Repeat the asserts from above.
733 guarantee(cmThread()->during_cycle(), "invariant");
734 guarantee(!g1h->mark_in_progress(), "invariant");
735 }
736
737 class NoteStartOfMarkHRClosure: public HeapRegionClosure {
738 public:
739 bool doHeapRegion(HeapRegion* r) {
740 if (!r->continuesHumongous()) {
741 r->note_start_of_marking();
742 }
743 return false;
744 }
745 };
746
747 void ConcurrentMark::checkpointRootsInitialPre() {
748 G1CollectedHeap* g1h = G1CollectedHeap::heap();
749 G1CollectorPolicy* g1p = g1h->g1_policy();
750
751 _has_aborted = false;
752
753 #ifndef PRODUCT
754 if (G1PrintReachableAtInitialMark) {
755 print_reachable("at-cycle-start",
756 VerifyOption_G1UsePrevMarking, true /* all */);
757 }
758 #endif
759
760 // Initialise marking structures. This has to be done in a STW phase.
761 reset();
762
763 // For each region note start of marking.
764 NoteStartOfMarkHRClosure startcl;
765 g1h->heap_region_iterate(&startcl);
766 }
767
768
769 void ConcurrentMark::checkpointRootsInitialPost() {
770 G1CollectedHeap* g1h = G1CollectedHeap::heap();
771
772 // If we force an overflow during remark, the remark operation will
773 // actually abort and we'll restart concurrent marking. If we always
774 // force an oveflow during remark we'll never actually complete the
775 // marking phase. So, we initilize this here, at the start of the
776 // cycle, so that at the remaining overflow number will decrease at
777 // every remark and we'll eventually not need to cause one.
778 force_overflow_stw()->init();
779
780 // Start Concurrent Marking weak-reference discovery.
781 ReferenceProcessor* rp = g1h->ref_processor_cm();
782 // enable ("weak") refs discovery
783 rp->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
784 rp->setup_policy(false); // snapshot the soft ref policy to be used in this cycle
785
786 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
787 // This is the start of the marking cycle, we're expected all
788 // threads to have SATB queues with active set to false.
789 satb_mq_set.set_active_all_threads(true, /* new active value */
790 false /* expected_active */);
791
792 _root_regions.prepare_for_scan();
793
794 // update_g1_committed() will be called at the end of an evac pause
795 // when marking is on. So, it's also called at the end of the
796 // initial-mark pause to update the heap end, if the heap expands
797 // during it. No need to call it here.
798 }
799
800 /*
801 * Notice that in the next two methods, we actually leave the STS
802 * during the barrier sync and join it immediately afterwards. If we
803 * do not do this, the following deadlock can occur: one thread could
804 * be in the barrier sync code, waiting for the other thread to also
805 * sync up, whereas another one could be trying to yield, while also
806 * waiting for the other threads to sync up too.
807 *
808 * Note, however, that this code is also used during remark and in
809 * this case we should not attempt to leave / enter the STS, otherwise
810 * we'll either hit an asseert (debug / fastdebug) or deadlock
811 * (product). So we should only leave / enter the STS if we are
812 * operating concurrently.
813 *
814 * Because the thread that does the sync barrier has left the STS, it
815 * is possible to be suspended for a Full GC or an evacuation pause
816 * could occur. This is actually safe, since the entering the sync
817 * barrier is one of the last things do_marking_step() does, and it
818 * doesn't manipulate any data structures afterwards.
819 */
820
821 void ConcurrentMark::enter_first_sync_barrier(int task_num) {
822 if (verbose_low()) {
823 gclog_or_tty->print_cr("[%d] entering first barrier", task_num);
824 }
825
826 if (concurrent()) {
827 ConcurrentGCThread::stsLeave();
828 }
829 _first_overflow_barrier_sync.enter();
830 if (concurrent()) {
831 ConcurrentGCThread::stsJoin();
832 }
833 // at this point everyone should have synced up and not be doing any
834 // more work
835
836 if (verbose_low()) {
837 gclog_or_tty->print_cr("[%d] leaving first barrier", task_num);
838 }
839
840 // let task 0 do this
841 if (task_num == 0) {
842 // task 0 is responsible for clearing the global data structures
843 // We should be here because of an overflow. During STW we should
844 // not clear the overflow flag since we rely on it being true when
845 // we exit this method to abort the pause and restart concurent
846 // marking.
847 clear_marking_state(concurrent() /* clear_overflow */);
848 force_overflow()->update();
849
850 if (G1Log::fine()) {
851 gclog_or_tty->date_stamp(PrintGCDateStamps);
852 gclog_or_tty->stamp(PrintGCTimeStamps);
853 gclog_or_tty->print_cr("[GC concurrent-mark-reset-for-overflow]");
854 }
855 }
856
857 // after this, each task should reset its own data structures then
858 // then go into the second barrier
859 }
860
861 void ConcurrentMark::enter_second_sync_barrier(int task_num) {
862 if (verbose_low()) {
863 gclog_or_tty->print_cr("[%d] entering second barrier", task_num);
864 }
865
866 if (concurrent()) {
867 ConcurrentGCThread::stsLeave();
868 }
869 _second_overflow_barrier_sync.enter();
870 if (concurrent()) {
871 ConcurrentGCThread::stsJoin();
872 }
873 // at this point everything should be re-initialised and ready to go
874
875 if (verbose_low()) {
876 gclog_or_tty->print_cr("[%d] leaving second barrier", task_num);
877 }
878 }
879
880 #ifndef PRODUCT
881 void ForceOverflowSettings::init() {
882 _num_remaining = G1ConcMarkForceOverflow;
883 _force = false;
884 update();
885 }
886
887 void ForceOverflowSettings::update() {
888 if (_num_remaining > 0) {
889 _num_remaining -= 1;
890 _force = true;
891 } else {
892 _force = false;
893 }
894 }
895
896 bool ForceOverflowSettings::should_force() {
897 if (_force) {
898 _force = false;
899 return true;
900 } else {
901 return false;
902 }
903 }
904 #endif // !PRODUCT
905
906 class CMConcurrentMarkingTask: public AbstractGangTask {
907 private:
908 ConcurrentMark* _cm;
909 ConcurrentMarkThread* _cmt;
910
911 public:
912 void work(uint worker_id) {
913 assert(Thread::current()->is_ConcurrentGC_thread(),
914 "this should only be done by a conc GC thread");
915 ResourceMark rm;
916
917 double start_vtime = os::elapsedVTime();
918
919 ConcurrentGCThread::stsJoin();
920
921 assert(worker_id < _cm->active_tasks(), "invariant");
922 CMTask* the_task = _cm->task(worker_id);
923 the_task->record_start_time();
924 if (!_cm->has_aborted()) {
925 do {
926 double start_vtime_sec = os::elapsedVTime();
927 double start_time_sec = os::elapsedTime();
928 double mark_step_duration_ms = G1ConcMarkStepDurationMillis;
929
930 the_task->do_marking_step(mark_step_duration_ms,
931 true /* do_stealing */,
932 true /* do_termination */);
933
934 double end_time_sec = os::elapsedTime();
935 double end_vtime_sec = os::elapsedVTime();
936 double elapsed_vtime_sec = end_vtime_sec - start_vtime_sec;
937 double elapsed_time_sec = end_time_sec - start_time_sec;
938 _cm->clear_has_overflown();
939
940 bool ret = _cm->do_yield_check(worker_id);
941
942 jlong sleep_time_ms;
943 if (!_cm->has_aborted() && the_task->has_aborted()) {
944 sleep_time_ms =
945 (jlong) (elapsed_vtime_sec * _cm->sleep_factor() * 1000.0);
946 ConcurrentGCThread::stsLeave();
947 os::sleep(Thread::current(), sleep_time_ms, false);
948 ConcurrentGCThread::stsJoin();
949 }
950 double end_time2_sec = os::elapsedTime();
951 double elapsed_time2_sec = end_time2_sec - start_time_sec;
952
953 #if 0
954 gclog_or_tty->print_cr("CM: elapsed %1.4lf ms, sleep %1.4lf ms, "
955 "overhead %1.4lf",
956 elapsed_vtime_sec * 1000.0, (double) sleep_time_ms,
957 the_task->conc_overhead(os::elapsedTime()) * 8.0);
958 gclog_or_tty->print_cr("elapsed time %1.4lf ms, time 2: %1.4lf ms",
959 elapsed_time_sec * 1000.0, elapsed_time2_sec * 1000.0);
960 #endif
961 } while (!_cm->has_aborted() && the_task->has_aborted());
962 }
963 the_task->record_end_time();
964 guarantee(!the_task->has_aborted() || _cm->has_aborted(), "invariant");
965
966 ConcurrentGCThread::stsLeave();
967
968 double end_vtime = os::elapsedVTime();
969 _cm->update_accum_task_vtime(worker_id, end_vtime - start_vtime);
970 }
971
972 CMConcurrentMarkingTask(ConcurrentMark* cm,
973 ConcurrentMarkThread* cmt) :
974 AbstractGangTask("Concurrent Mark"), _cm(cm), _cmt(cmt) { }
975
976 ~CMConcurrentMarkingTask() { }
977 };
978
979 // Calculates the number of active workers for a concurrent
980 // phase.
981 uint ConcurrentMark::calc_parallel_marking_threads() {
982 if (G1CollectedHeap::use_parallel_gc_threads()) {
983 uint n_conc_workers = 0;
984 if (!UseDynamicNumberOfGCThreads ||
985 (!FLAG_IS_DEFAULT(ConcGCThreads) &&
986 !ForceDynamicNumberOfGCThreads)) {
987 n_conc_workers = max_parallel_marking_threads();
988 } else {
989 n_conc_workers =
990 AdaptiveSizePolicy::calc_default_active_workers(
991 max_parallel_marking_threads(),
992 1, /* Minimum workers */
993 parallel_marking_threads(),
994 Threads::number_of_non_daemon_threads());
995 // Don't scale down "n_conc_workers" by scale_parallel_threads() because
996 // that scaling has already gone into "_max_parallel_marking_threads".
997 }
998 assert(n_conc_workers > 0, "Always need at least 1");
999 return n_conc_workers;
1000 }
1001 // If we are not running with any parallel GC threads we will not
1002 // have spawned any marking threads either. Hence the number of
1003 // concurrent workers should be 0.
1004 return 0;
1005 }
1006
1007 void ConcurrentMark::scanRootRegion(HeapRegion* hr, uint worker_id) {
1008 // Currently, only survivors can be root regions.
1009 assert(hr->next_top_at_mark_start() == hr->bottom(), "invariant");
1010 G1RootRegionScanClosure cl(_g1h, this, worker_id);
1011
1012 const uintx interval = PrefetchScanIntervalInBytes;
1013 HeapWord* curr = hr->bottom();
1014 const HeapWord* end = hr->top();
1015 while (curr < end) {
1016 Prefetch::read(curr, interval);
1017 oop obj = oop(curr);
1018 int size = obj->oop_iterate(&cl);
1019 assert(size == obj->size(), "sanity");
1020 curr += size;
1021 }
1022 }
1023
1024 class CMRootRegionScanTask : public AbstractGangTask {
1025 private:
1026 ConcurrentMark* _cm;
1027
1028 public:
1029 CMRootRegionScanTask(ConcurrentMark* cm) :
1030 AbstractGangTask("Root Region Scan"), _cm(cm) { }
1031
1032 void work(uint worker_id) {
1033 assert(Thread::current()->is_ConcurrentGC_thread(),
1034 "this should only be done by a conc GC thread");
1035
1036 CMRootRegions* root_regions = _cm->root_regions();
1037 HeapRegion* hr = root_regions->claim_next();
1038 while (hr != NULL) {
1039 _cm->scanRootRegion(hr, worker_id);
1040 hr = root_regions->claim_next();
1041 }
1042 }
1043 };
1044
1045 void ConcurrentMark::scanRootRegions() {
1046 // scan_in_progress() will have been set to true only if there was
1047 // at least one root region to scan. So, if it's false, we
1048 // should not attempt to do any further work.
1049 if (root_regions()->scan_in_progress()) {
1050 _parallel_marking_threads = calc_parallel_marking_threads();
1051 assert(parallel_marking_threads() <= max_parallel_marking_threads(),
1052 "Maximum number of marking threads exceeded");
1053 uint active_workers = MAX2(1U, parallel_marking_threads());
1054
1055 CMRootRegionScanTask task(this);
1056 if (parallel_marking_threads() > 0) {
1057 _parallel_workers->set_active_workers((int) active_workers);
1058 _parallel_workers->run_task(&task);
1059 } else {
1060 task.work(0);
1061 }
1062
1063 // It's possible that has_aborted() is true here without actually
1064 // aborting the survivor scan earlier. This is OK as it's
1065 // mainly used for sanity checking.
1066 root_regions()->scan_finished();
1067 }
1068 }
1069
1070 void ConcurrentMark::markFromRoots() {
1071 // we might be tempted to assert that:
1072 // assert(asynch == !SafepointSynchronize::is_at_safepoint(),
1073 // "inconsistent argument?");
1074 // However that wouldn't be right, because it's possible that
1075 // a safepoint is indeed in progress as a younger generation
1076 // stop-the-world GC happens even as we mark in this generation.
1077
1078 _restart_for_overflow = false;
1079 force_overflow_conc()->init();
1080
1081 // _g1h has _n_par_threads
1082 _parallel_marking_threads = calc_parallel_marking_threads();
1083 assert(parallel_marking_threads() <= max_parallel_marking_threads(),
1084 "Maximum number of marking threads exceeded");
1085
1086 uint active_workers = MAX2(1U, parallel_marking_threads());
1087
1088 // Parallel task terminator is set in "set_phase()"
1089 set_phase(active_workers, true /* concurrent */);
1090
1091 CMConcurrentMarkingTask markingTask(this, cmThread());
1092 if (parallel_marking_threads() > 0) {
1093 _parallel_workers->set_active_workers((int)active_workers);
1094 // Don't set _n_par_threads because it affects MT in proceess_strong_roots()
1095 // and the decisions on that MT processing is made elsewhere.
1096 assert(_parallel_workers->active_workers() > 0, "Should have been set");
1097 _parallel_workers->run_task(&markingTask);
1098 } else {
1099 markingTask.work(0);
1100 }
1101 print_stats();
1102 }
1103
1104 void ConcurrentMark::checkpointRootsFinal(bool clear_all_soft_refs) {
1105 // world is stopped at this checkpoint
1106 assert(SafepointSynchronize::is_at_safepoint(),
1107 "world should be stopped");
1108
1109 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1110
1111 // If a full collection has happened, we shouldn't do this.
1112 if (has_aborted()) {
1113 g1h->set_marking_complete(); // So bitmap clearing isn't confused
1114 return;
1115 }
1116
1117 SvcGCMarker sgcm(SvcGCMarker::OTHER);
1118
1119 if (VerifyDuringGC) {
1120 HandleMark hm; // handle scope
1121 gclog_or_tty->print(" VerifyDuringGC:(before)");
1122 Universe::heap()->prepare_for_verify();
1123 Universe::verify(/* silent */ false,
1124 /* option */ VerifyOption_G1UsePrevMarking);
1125 }
1126
1127 G1CollectorPolicy* g1p = g1h->g1_policy();
1128 g1p->record_concurrent_mark_remark_start();
1129
1130 double start = os::elapsedTime();
1131
1132 checkpointRootsFinalWork();
1133
1134 double mark_work_end = os::elapsedTime();
1135
1136 weakRefsWork(clear_all_soft_refs);
1137
1138 if (has_overflown()) {
1139 // Oops. We overflowed. Restart concurrent marking.
1140 _restart_for_overflow = true;
1141 // Clear the flag. We do not need it any more.
1142 clear_has_overflown();
1143 if (G1TraceMarkStackOverflow) {
1144 gclog_or_tty->print_cr("\nRemark led to restart for overflow.");
1145 }
1146 } else {
1147 // Aggregate the per-task counting data that we have accumulated
1148 // while marking.
1149 aggregate_count_data();
1150
1151 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
1152 // We're done with marking.
1153 // This is the end of the marking cycle, we're expected all
1154 // threads to have SATB queues with active set to true.
1155 satb_mq_set.set_active_all_threads(false, /* new active value */
1156 true /* expected_active */);
1157
1158 if (VerifyDuringGC) {
1159 HandleMark hm; // handle scope
1160 gclog_or_tty->print(" VerifyDuringGC:(after)");
1161 Universe::heap()->prepare_for_verify();
1162 Universe::verify(/* silent */ false,
1163 /* option */ VerifyOption_G1UseNextMarking);
1164 }
1165 assert(!restart_for_overflow(), "sanity");
1166 }
1167
1168 // Reset the marking state if marking completed
1169 if (!restart_for_overflow()) {
1170 set_non_marking_state();
1171 }
1172
1173 #if VERIFY_OBJS_PROCESSED
1174 _scan_obj_cl.objs_processed = 0;
1175 ThreadLocalObjQueue::objs_enqueued = 0;
1176 #endif
1177
1178 // Statistics
1179 double now = os::elapsedTime();
1180 _remark_mark_times.add((mark_work_end - start) * 1000.0);
1181 _remark_weak_ref_times.add((now - mark_work_end) * 1000.0);
1182 _remark_times.add((now - start) * 1000.0);
1183
1184 g1p->record_concurrent_mark_remark_end();
1185 }
1186
1187 // Base class of the closures that finalize and verify the
1188 // liveness counting data.
1189 class CMCountDataClosureBase: public HeapRegionClosure {
1190 protected:
1191 G1CollectedHeap* _g1h;
1192 ConcurrentMark* _cm;
1193 CardTableModRefBS* _ct_bs;
1194
1195 BitMap* _region_bm;
1196 BitMap* _card_bm;
1197
1198 // Takes a region that's not empty (i.e., it has at least one
1199 // live object in it and sets its corresponding bit on the region
1200 // bitmap to 1. If the region is "starts humongous" it will also set
1201 // to 1 the bits on the region bitmap that correspond to its
1202 // associated "continues humongous" regions.
1203 void set_bit_for_region(HeapRegion* hr) {
1204 assert(!hr->continuesHumongous(), "should have filtered those out");
1205
1206 BitMap::idx_t index = (BitMap::idx_t) hr->hrs_index();
1207 if (!hr->startsHumongous()) {
1208 // Normal (non-humongous) case: just set the bit.
1209 _region_bm->par_at_put(index, true);
1210 } else {
1211 // Starts humongous case: calculate how many regions are part of
1212 // this humongous region and then set the bit range.
1213 BitMap::idx_t end_index = (BitMap::idx_t) hr->last_hc_index();
1214 _region_bm->par_at_put_range(index, end_index, true);
1215 }
1216 }
1217
1218 public:
1219 CMCountDataClosureBase(G1CollectedHeap* g1h,
1220 BitMap* region_bm, BitMap* card_bm):
1221 _g1h(g1h), _cm(g1h->concurrent_mark()),
1222 _ct_bs((CardTableModRefBS*) (g1h->barrier_set())),
1223 _region_bm(region_bm), _card_bm(card_bm) { }
1224 };
1225
1226 // Closure that calculates the # live objects per region. Used
1227 // for verification purposes during the cleanup pause.
1228 class CalcLiveObjectsClosure: public CMCountDataClosureBase {
1229 CMBitMapRO* _bm;
1230 size_t _region_marked_bytes;
1231
1232 public:
1233 CalcLiveObjectsClosure(CMBitMapRO *bm, G1CollectedHeap* g1h,
1234 BitMap* region_bm, BitMap* card_bm) :
1235 CMCountDataClosureBase(g1h, region_bm, card_bm),
1236 _bm(bm), _region_marked_bytes(0) { }
1237
1238 bool doHeapRegion(HeapRegion* hr) {
1239
1240 if (hr->continuesHumongous()) {
1241 // We will ignore these here and process them when their
1242 // associated "starts humongous" region is processed (see
1243 // set_bit_for_heap_region()). Note that we cannot rely on their
1244 // associated "starts humongous" region to have their bit set to
1245 // 1 since, due to the region chunking in the parallel region
1246 // iteration, a "continues humongous" region might be visited
1247 // before its associated "starts humongous".
1248 return false;
1249 }
1250
1251 HeapWord* ntams = hr->next_top_at_mark_start();
1252 HeapWord* start = hr->bottom();
1253
1254 assert(start <= hr->end() && start <= ntams && ntams <= hr->end(),
1255 err_msg("Preconditions not met - "
1256 "start: "PTR_FORMAT", ntams: "PTR_FORMAT", end: "PTR_FORMAT,
1257 start, ntams, hr->end()));
1258
1259 // Find the first marked object at or after "start".
1260 start = _bm->getNextMarkedWordAddress(start, ntams);
1261
1262 size_t marked_bytes = 0;
1263
1264 while (start < ntams) {
1265 oop obj = oop(start);
1266 int obj_sz = obj->size();
1267 HeapWord* obj_end = start + obj_sz;
1268
1269 BitMap::idx_t start_idx = _cm->card_bitmap_index_for(start);
1270 BitMap::idx_t end_idx = _cm->card_bitmap_index_for(obj_end);
1271
1272 // Note: if we're looking at the last region in heap - obj_end
1273 // could be actually outside the heap and end_idx correspond
1274 // to a card that is also outside the heap.
1275 if (_g1h->is_in_g1_reserved(obj_end) && !_ct_bs->is_card_aligned(obj_end)) {
1276 // end of object is not card aligned - increment to cover
1277 // all the cards spanned by the object
1278 end_idx += 1;
1279 }
1280
1281 // Set the bits in the card BM for the cards spanned by this object.
1282 _cm->set_card_bitmap_range(_card_bm, start_idx, end_idx, true /* is_par */);
1283
1284 // Add the size of this object to the number of marked bytes.
1285 marked_bytes += (size_t)obj_sz * HeapWordSize;
1286
1287 // Find the next marked object after this one.
1288 start = _bm->getNextMarkedWordAddress(obj_end, ntams);
1289 }
1290
1291 // Mark the allocated-since-marking portion...
1292 HeapWord* top = hr->top();
1293 if (ntams < top) {
1294 BitMap::idx_t start_idx = _cm->card_bitmap_index_for(ntams);
1295 BitMap::idx_t end_idx = _cm->card_bitmap_index_for(top);
1296
1297 // Note: if we're looking at the last region in heap - top
1298 // could actually be outside the heap and end_idx correspond
1299 // to a card that is also outside the heap.
1300 if (_g1h->is_in_g1_reserved(top) && !_ct_bs->is_card_aligned(top)) {
1301 // end of object is not card aligned - increment to cover
1302 // all the cards spanned by the object
1303 end_idx += 1;
1304 }
1305 _cm->set_card_bitmap_range(_card_bm, start_idx, end_idx, true /* is_par */);
1306
1307 // This definitely means the region has live objects.
1308 set_bit_for_region(hr);
1309 }
1310
1311 // Update the live region bitmap.
1312 if (marked_bytes > 0) {
1313 set_bit_for_region(hr);
1314 }
1315
1316 // Set the marked bytes for the current region so that
1317 // it can be queried by a calling verificiation routine
1318 _region_marked_bytes = marked_bytes;
1319
1320 return false;
1321 }
1322
1323 size_t region_marked_bytes() const { return _region_marked_bytes; }
1324 };
1325
1326 // Heap region closure used for verifying the counting data
1327 // that was accumulated concurrently and aggregated during
1328 // the remark pause. This closure is applied to the heap
1329 // regions during the STW cleanup pause.
1330
1331 class VerifyLiveObjectDataHRClosure: public HeapRegionClosure {
1332 G1CollectedHeap* _g1h;
1333 ConcurrentMark* _cm;
1334 CalcLiveObjectsClosure _calc_cl;
1335 BitMap* _region_bm; // Region BM to be verified
1336 BitMap* _card_bm; // Card BM to be verified
1337 bool _verbose; // verbose output?
1338
1339 BitMap* _exp_region_bm; // Expected Region BM values
1340 BitMap* _exp_card_bm; // Expected card BM values
1341
1342 int _failures;
1343
1344 public:
1345 VerifyLiveObjectDataHRClosure(G1CollectedHeap* g1h,
1346 BitMap* region_bm,
1347 BitMap* card_bm,
1348 BitMap* exp_region_bm,
1349 BitMap* exp_card_bm,
1350 bool verbose) :
1351 _g1h(g1h), _cm(g1h->concurrent_mark()),
1352 _calc_cl(_cm->nextMarkBitMap(), g1h, exp_region_bm, exp_card_bm),
1353 _region_bm(region_bm), _card_bm(card_bm), _verbose(verbose),
1354 _exp_region_bm(exp_region_bm), _exp_card_bm(exp_card_bm),
1355 _failures(0) { }
1356
1357 int failures() const { return _failures; }
1358
1359 bool doHeapRegion(HeapRegion* hr) {
1360 if (hr->continuesHumongous()) {
1361 // We will ignore these here and process them when their
1362 // associated "starts humongous" region is processed (see
1363 // set_bit_for_heap_region()). Note that we cannot rely on their
1364 // associated "starts humongous" region to have their bit set to
1365 // 1 since, due to the region chunking in the parallel region
1366 // iteration, a "continues humongous" region might be visited
1367 // before its associated "starts humongous".
1368 return false;
1369 }
1370
1371 int failures = 0;
1372
1373 // Call the CalcLiveObjectsClosure to walk the marking bitmap for
1374 // this region and set the corresponding bits in the expected region
1375 // and card bitmaps.
1376 bool res = _calc_cl.doHeapRegion(hr);
1377 assert(res == false, "should be continuing");
1378
1379 MutexLockerEx x((_verbose ? ParGCRareEvent_lock : NULL),
1380 Mutex::_no_safepoint_check_flag);
1381
1382 // Verify the marked bytes for this region.
1383 size_t exp_marked_bytes = _calc_cl.region_marked_bytes();
1384 size_t act_marked_bytes = hr->next_marked_bytes();
1385
1386 // We're not OK if expected marked bytes > actual marked bytes. It means
1387 // we have missed accounting some objects during the actual marking.
1388 if (exp_marked_bytes > act_marked_bytes) {
1389 if (_verbose) {
1390 gclog_or_tty->print_cr("Region %u: marked bytes mismatch: "
1391 "expected: " SIZE_FORMAT ", actual: " SIZE_FORMAT,
1392 hr->hrs_index(), exp_marked_bytes, act_marked_bytes);
1393 }
1394 failures += 1;
1395 }
1396
1397 // Verify the bit, for this region, in the actual and expected
1398 // (which was just calculated) region bit maps.
1399 // We're not OK if the bit in the calculated expected region
1400 // bitmap is set and the bit in the actual region bitmap is not.
1401 BitMap::idx_t index = (BitMap::idx_t) hr->hrs_index();
1402
1403 bool expected = _exp_region_bm->at(index);
1404 bool actual = _region_bm->at(index);
1405 if (expected && !actual) {
1406 if (_verbose) {
1407 gclog_or_tty->print_cr("Region %u: region bitmap mismatch: "
1408 "expected: %s, actual: %s",
1409 hr->hrs_index(),
1410 BOOL_TO_STR(expected), BOOL_TO_STR(actual));
1411 }
1412 failures += 1;
1413 }
1414
1415 // Verify that the card bit maps for the cards spanned by the current
1416 // region match. We have an error if we have a set bit in the expected
1417 // bit map and the corresponding bit in the actual bitmap is not set.
1418
1419 BitMap::idx_t start_idx = _cm->card_bitmap_index_for(hr->bottom());
1420 BitMap::idx_t end_idx = _cm->card_bitmap_index_for(hr->top());
1421
1422 for (BitMap::idx_t i = start_idx; i < end_idx; i+=1) {
1423 expected = _exp_card_bm->at(i);
1424 actual = _card_bm->at(i);
1425
1426 if (expected && !actual) {
1427 if (_verbose) {
1428 gclog_or_tty->print_cr("Region %u: card bitmap mismatch at " SIZE_FORMAT ": "
1429 "expected: %s, actual: %s",
1430 hr->hrs_index(), i,
1431 BOOL_TO_STR(expected), BOOL_TO_STR(actual));
1432 }
1433 failures += 1;
1434 }
1435 }
1436
1437 if (failures > 0 && _verbose) {
1438 gclog_or_tty->print_cr("Region " HR_FORMAT ", ntams: " PTR_FORMAT ", "
1439 "marked_bytes: calc/actual " SIZE_FORMAT "/" SIZE_FORMAT,
1440 HR_FORMAT_PARAMS(hr), hr->next_top_at_mark_start(),
1441 _calc_cl.region_marked_bytes(), hr->next_marked_bytes());
1442 }
1443
1444 _failures += failures;
1445
1446 // We could stop iteration over the heap when we
1447 // find the first violating region by returning true.
1448 return false;
1449 }
1450 };
1451
1452
1453 class G1ParVerifyFinalCountTask: public AbstractGangTask {
1454 protected:
1455 G1CollectedHeap* _g1h;
1456 ConcurrentMark* _cm;
1457 BitMap* _actual_region_bm;
1458 BitMap* _actual_card_bm;
1459
1460 uint _n_workers;
1461
1462 BitMap* _expected_region_bm;
1463 BitMap* _expected_card_bm;
1464
1465 int _failures;
1466 bool _verbose;
1467
1468 public:
1469 G1ParVerifyFinalCountTask(G1CollectedHeap* g1h,
1470 BitMap* region_bm, BitMap* card_bm,
1471 BitMap* expected_region_bm, BitMap* expected_card_bm)
1472 : AbstractGangTask("G1 verify final counting"),
1473 _g1h(g1h), _cm(_g1h->concurrent_mark()),
1474 _actual_region_bm(region_bm), _actual_card_bm(card_bm),
1475 _expected_region_bm(expected_region_bm), _expected_card_bm(expected_card_bm),
1476 _failures(0), _verbose(false),
1477 _n_workers(0) {
1478 assert(VerifyDuringGC, "don't call this otherwise");
1479
1480 // Use the value already set as the number of active threads
1481 // in the call to run_task().
1482 if (G1CollectedHeap::use_parallel_gc_threads()) {
1483 assert( _g1h->workers()->active_workers() > 0,
1484 "Should have been previously set");
1485 _n_workers = _g1h->workers()->active_workers();
1486 } else {
1487 _n_workers = 1;
1488 }
1489
1490 assert(_expected_card_bm->size() == _actual_card_bm->size(), "sanity");
1491 assert(_expected_region_bm->size() == _actual_region_bm->size(), "sanity");
1492
1493 _verbose = _cm->verbose_medium();
1494 }
1495
1496 void work(uint worker_id) {
1497 assert(worker_id < _n_workers, "invariant");
1498
1499 VerifyLiveObjectDataHRClosure verify_cl(_g1h,
1500 _actual_region_bm, _actual_card_bm,
1501 _expected_region_bm,
1502 _expected_card_bm,
1503 _verbose);
1504
1505 if (G1CollectedHeap::use_parallel_gc_threads()) {
1506 _g1h->heap_region_par_iterate_chunked(&verify_cl,
1507 worker_id,
1508 _n_workers,
1509 HeapRegion::VerifyCountClaimValue);
1510 } else {
1511 _g1h->heap_region_iterate(&verify_cl);
1512 }
1513
1514 Atomic::add(verify_cl.failures(), &_failures);
1515 }
1516
1517 int failures() const { return _failures; }
1518 };
1519
1520 // Closure that finalizes the liveness counting data.
1521 // Used during the cleanup pause.
1522 // Sets the bits corresponding to the interval [NTAMS, top]
1523 // (which contains the implicitly live objects) in the
1524 // card liveness bitmap. Also sets the bit for each region,
1525 // containing live data, in the region liveness bitmap.
1526
1527 class FinalCountDataUpdateClosure: public CMCountDataClosureBase {
1528 public:
1529 FinalCountDataUpdateClosure(G1CollectedHeap* g1h,
1530 BitMap* region_bm,
1531 BitMap* card_bm) :
1532 CMCountDataClosureBase(g1h, region_bm, card_bm) { }
1533
1534 bool doHeapRegion(HeapRegion* hr) {
1535
1536 if (hr->continuesHumongous()) {
1537 // We will ignore these here and process them when their
1538 // associated "starts humongous" region is processed (see
1539 // set_bit_for_heap_region()). Note that we cannot rely on their
1540 // associated "starts humongous" region to have their bit set to
1541 // 1 since, due to the region chunking in the parallel region
1542 // iteration, a "continues humongous" region might be visited
1543 // before its associated "starts humongous".
1544 return false;
1545 }
1546
1547 HeapWord* ntams = hr->next_top_at_mark_start();
1548 HeapWord* top = hr->top();
1549
1550 assert(hr->bottom() <= ntams && ntams <= hr->end(), "Preconditions.");
1551
1552 // Mark the allocated-since-marking portion...
1553 if (ntams < top) {
1554 // This definitely means the region has live objects.
1555 set_bit_for_region(hr);
1556
1557 // Now set the bits in the card bitmap for [ntams, top)
1558 BitMap::idx_t start_idx = _cm->card_bitmap_index_for(ntams);
1559 BitMap::idx_t end_idx = _cm->card_bitmap_index_for(top);
1560
1561 // Note: if we're looking at the last region in heap - top
1562 // could actually be outside the heap and end_idx correspond
1563 // to a card that is also outside the heap.
1564 if (_g1h->is_in_g1_reserved(top) && !_ct_bs->is_card_aligned(top)) {
1565 // end of object is not card aligned - increment to cover
1566 // all the cards spanned by the object
1567 end_idx += 1;
1568 }
1569
1570 assert(end_idx <= _card_bm->size(),
1571 err_msg("oob: end_idx= "SIZE_FORMAT", bitmap size= "SIZE_FORMAT,
1572 end_idx, _card_bm->size()));
1573 assert(start_idx < _card_bm->size(),
1574 err_msg("oob: start_idx= "SIZE_FORMAT", bitmap size= "SIZE_FORMAT,
1575 start_idx, _card_bm->size()));
1576
1577 _cm->set_card_bitmap_range(_card_bm, start_idx, end_idx, true /* is_par */);
1578 }
1579
1580 // Set the bit for the region if it contains live data
1581 if (hr->next_marked_bytes() > 0) {
1582 set_bit_for_region(hr);
1583 }
1584
1585 return false;
1586 }
1587 };
1588
1589 class G1ParFinalCountTask: public AbstractGangTask {
1590 protected:
1591 G1CollectedHeap* _g1h;
1592 ConcurrentMark* _cm;
1593 BitMap* _actual_region_bm;
1594 BitMap* _actual_card_bm;
1595
1596 uint _n_workers;
1597
1598 public:
1599 G1ParFinalCountTask(G1CollectedHeap* g1h, BitMap* region_bm, BitMap* card_bm)
1600 : AbstractGangTask("G1 final counting"),
1601 _g1h(g1h), _cm(_g1h->concurrent_mark()),
1602 _actual_region_bm(region_bm), _actual_card_bm(card_bm),
1603 _n_workers(0) {
1604 // Use the value already set as the number of active threads
1605 // in the call to run_task().
1606 if (G1CollectedHeap::use_parallel_gc_threads()) {
1607 assert( _g1h->workers()->active_workers() > 0,
1608 "Should have been previously set");
1609 _n_workers = _g1h->workers()->active_workers();
1610 } else {
1611 _n_workers = 1;
1612 }
1613 }
1614
1615 void work(uint worker_id) {
1616 assert(worker_id < _n_workers, "invariant");
1617
1618 FinalCountDataUpdateClosure final_update_cl(_g1h,
1619 _actual_region_bm,
1620 _actual_card_bm);
1621
1622 if (G1CollectedHeap::use_parallel_gc_threads()) {
1623 _g1h->heap_region_par_iterate_chunked(&final_update_cl,
1624 worker_id,
1625 _n_workers,
1626 HeapRegion::FinalCountClaimValue);
1627 } else {
1628 _g1h->heap_region_iterate(&final_update_cl);
1629 }
1630 }
1631 };
1632
1633 class G1ParNoteEndTask;
1634
1635 class G1NoteEndOfConcMarkClosure : public HeapRegionClosure {
1636 G1CollectedHeap* _g1;
1637 int _worker_num;
1638 size_t _max_live_bytes;
1639 uint _regions_claimed;
1640 size_t _freed_bytes;
1641 FreeRegionList* _local_cleanup_list;
1642 OldRegionSet* _old_proxy_set;
1643 HumongousRegionSet* _humongous_proxy_set;
1644 HRRSCleanupTask* _hrrs_cleanup_task;
1645 double _claimed_region_time;
1646 double _max_region_time;
1647
1648 public:
1649 G1NoteEndOfConcMarkClosure(G1CollectedHeap* g1,
1650 int worker_num,
1651 FreeRegionList* local_cleanup_list,
1652 OldRegionSet* old_proxy_set,
1653 HumongousRegionSet* humongous_proxy_set,
1654 HRRSCleanupTask* hrrs_cleanup_task) :
1655 _g1(g1), _worker_num(worker_num),
1656 _max_live_bytes(0), _regions_claimed(0),
1657 _freed_bytes(0),
1658 _claimed_region_time(0.0), _max_region_time(0.0),
1659 _local_cleanup_list(local_cleanup_list),
1660 _old_proxy_set(old_proxy_set),
1661 _humongous_proxy_set(humongous_proxy_set),
1662 _hrrs_cleanup_task(hrrs_cleanup_task) { }
1663
1664 size_t freed_bytes() { return _freed_bytes; }
1665
1666 bool doHeapRegion(HeapRegion *hr) {
1667 if (hr->continuesHumongous()) {
1668 return false;
1669 }
1670 // We use a claim value of zero here because all regions
1671 // were claimed with value 1 in the FinalCount task.
1672 _g1->reset_gc_time_stamps(hr);
1673 double start = os::elapsedTime();
1674 _regions_claimed++;
1675 hr->note_end_of_marking();
1676 _max_live_bytes += hr->max_live_bytes();
1677 _g1->free_region_if_empty(hr,
1678 &_freed_bytes,
1679 _local_cleanup_list,
1680 _old_proxy_set,
1681 _humongous_proxy_set,
1682 _hrrs_cleanup_task,
1683 true /* par */);
1684 double region_time = (os::elapsedTime() - start);
1685 _claimed_region_time += region_time;
1686 if (region_time > _max_region_time) {
1687 _max_region_time = region_time;
1688 }
1689 return false;
1690 }
1691
1692 size_t max_live_bytes() { return _max_live_bytes; }
1693 uint regions_claimed() { return _regions_claimed; }
1694 double claimed_region_time_sec() { return _claimed_region_time; }
1695 double max_region_time_sec() { return _max_region_time; }
1696 };
1697
1698 class G1ParNoteEndTask: public AbstractGangTask {
1699 friend class G1NoteEndOfConcMarkClosure;
1700
1701 protected:
1702 G1CollectedHeap* _g1h;
1703 size_t _max_live_bytes;
1704 size_t _freed_bytes;
1705 FreeRegionList* _cleanup_list;
1706
1707 public:
1708 G1ParNoteEndTask(G1CollectedHeap* g1h,
1709 FreeRegionList* cleanup_list) :
1710 AbstractGangTask("G1 note end"), _g1h(g1h),
1711 _max_live_bytes(0), _freed_bytes(0), _cleanup_list(cleanup_list) { }
1712
1713 void work(uint worker_id) {
1714 double start = os::elapsedTime();
1715 FreeRegionList local_cleanup_list("Local Cleanup List");
1716 OldRegionSet old_proxy_set("Local Cleanup Old Proxy Set");
1717 HumongousRegionSet humongous_proxy_set("Local Cleanup Humongous Proxy Set");
1718 HRRSCleanupTask hrrs_cleanup_task;
1719 G1NoteEndOfConcMarkClosure g1_note_end(_g1h, worker_id, &local_cleanup_list,
1720 &old_proxy_set,
1721 &humongous_proxy_set,
1722 &hrrs_cleanup_task);
1723 if (G1CollectedHeap::use_parallel_gc_threads()) {
1724 _g1h->heap_region_par_iterate_chunked(&g1_note_end, worker_id,
1725 _g1h->workers()->active_workers(),
1726 HeapRegion::NoteEndClaimValue);
1727 } else {
1728 _g1h->heap_region_iterate(&g1_note_end);
1729 }
1730 assert(g1_note_end.complete(), "Shouldn't have yielded!");
1731
1732 // Now update the lists
1733 _g1h->update_sets_after_freeing_regions(g1_note_end.freed_bytes(),
1734 NULL /* free_list */,
1735 &old_proxy_set,
1736 &humongous_proxy_set,
1737 true /* par */);
1738 {
1739 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
1740 _max_live_bytes += g1_note_end.max_live_bytes();
1741 _freed_bytes += g1_note_end.freed_bytes();
1742
1743 // If we iterate over the global cleanup list at the end of
1744 // cleanup to do this printing we will not guarantee to only
1745 // generate output for the newly-reclaimed regions (the list
1746 // might not be empty at the beginning of cleanup; we might
1747 // still be working on its previous contents). So we do the
1748 // printing here, before we append the new regions to the global
1749 // cleanup list.
1750
1751 G1HRPrinter* hr_printer = _g1h->hr_printer();
1752 if (hr_printer->is_active()) {
1753 HeapRegionLinkedListIterator iter(&local_cleanup_list);
1754 while (iter.more_available()) {
1755 HeapRegion* hr = iter.get_next();
1756 hr_printer->cleanup(hr);
1757 }
1758 }
1759
1760 _cleanup_list->add_as_tail(&local_cleanup_list);
1761 assert(local_cleanup_list.is_empty(), "post-condition");
1762
1763 HeapRegionRemSet::finish_cleanup_task(&hrrs_cleanup_task);
1764 }
1765 }
1766 size_t max_live_bytes() { return _max_live_bytes; }
1767 size_t freed_bytes() { return _freed_bytes; }
1768 };
1769
1770 class G1ParScrubRemSetTask: public AbstractGangTask {
1771 protected:
1772 G1RemSet* _g1rs;
1773 BitMap* _region_bm;
1774 BitMap* _card_bm;
1775 public:
1776 G1ParScrubRemSetTask(G1CollectedHeap* g1h,
1777 BitMap* region_bm, BitMap* card_bm) :
1778 AbstractGangTask("G1 ScrubRS"), _g1rs(g1h->g1_rem_set()),
1779 _region_bm(region_bm), _card_bm(card_bm) { }
1780
1781 void work(uint worker_id) {
1782 if (G1CollectedHeap::use_parallel_gc_threads()) {
1783 _g1rs->scrub_par(_region_bm, _card_bm, worker_id,
1784 HeapRegion::ScrubRemSetClaimValue);
1785 } else {
1786 _g1rs->scrub(_region_bm, _card_bm);
1787 }
1788 }
1789
1790 };
1791
1792 void ConcurrentMark::cleanup() {
1793 // world is stopped at this checkpoint
1794 assert(SafepointSynchronize::is_at_safepoint(),
1795 "world should be stopped");
1796 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1797
1798 // If a full collection has happened, we shouldn't do this.
1799 if (has_aborted()) {
1800 g1h->set_marking_complete(); // So bitmap clearing isn't confused
1801 return;
1802 }
1803
1804 HRSPhaseSetter x(HRSPhaseCleanup);
1805 g1h->verify_region_sets_optional();
1806
1807 if (VerifyDuringGC) {
1808 HandleMark hm; // handle scope
1809 gclog_or_tty->print(" VerifyDuringGC:(before)");
1810 Universe::heap()->prepare_for_verify();
1811 Universe::verify(/* silent */ false,
1812 /* option */ VerifyOption_G1UsePrevMarking);
1813 }
1814
1815 G1CollectorPolicy* g1p = G1CollectedHeap::heap()->g1_policy();
1816 g1p->record_concurrent_mark_cleanup_start();
1817
1818 double start = os::elapsedTime();
1819
1820 HeapRegionRemSet::reset_for_cleanup_tasks();
1821
1822 uint n_workers;
1823
1824 // Do counting once more with the world stopped for good measure.
1825 G1ParFinalCountTask g1_par_count_task(g1h, &_region_bm, &_card_bm);
1826
1827 if (G1CollectedHeap::use_parallel_gc_threads()) {
1828 assert(g1h->check_heap_region_claim_values(HeapRegion::InitialClaimValue),
1829 "sanity check");
1830
1831 g1h->set_par_threads();
1832 n_workers = g1h->n_par_threads();
1833 assert(g1h->n_par_threads() == n_workers,
1834 "Should not have been reset");
1835 g1h->workers()->run_task(&g1_par_count_task);
1836 // Done with the parallel phase so reset to 0.
1837 g1h->set_par_threads(0);
1838
1839 assert(g1h->check_heap_region_claim_values(HeapRegion::FinalCountClaimValue),
1840 "sanity check");
1841 } else {
1842 n_workers = 1;
1843 g1_par_count_task.work(0);
1844 }
1845
1846 if (VerifyDuringGC) {
1847 // Verify that the counting data accumulated during marking matches
1848 // that calculated by walking the marking bitmap.
1849
1850 // Bitmaps to hold expected values
1851 BitMap expected_region_bm(_region_bm.size(), false);
1852 BitMap expected_card_bm(_card_bm.size(), false);
1853
1854 G1ParVerifyFinalCountTask g1_par_verify_task(g1h,
1855 &_region_bm,
1856 &_card_bm,
1857 &expected_region_bm,
1858 &expected_card_bm);
1859
1860 if (G1CollectedHeap::use_parallel_gc_threads()) {
1861 g1h->set_par_threads((int)n_workers);
1862 g1h->workers()->run_task(&g1_par_verify_task);
1863 // Done with the parallel phase so reset to 0.
1864 g1h->set_par_threads(0);
1865
1866 assert(g1h->check_heap_region_claim_values(HeapRegion::VerifyCountClaimValue),
1867 "sanity check");
1868 } else {
1869 g1_par_verify_task.work(0);
1870 }
1871
1872 guarantee(g1_par_verify_task.failures() == 0, "Unexpected accounting failures");
1873 }
1874
1875 size_t start_used_bytes = g1h->used();
1876 g1h->set_marking_complete();
1877
1878 double count_end = os::elapsedTime();
1879 double this_final_counting_time = (count_end - start);
1880 _total_counting_time += this_final_counting_time;
1881
1882 if (G1PrintRegionLivenessInfo) {
1883 G1PrintRegionLivenessInfoClosure cl(gclog_or_tty, "Post-Marking");
1884 _g1h->heap_region_iterate(&cl);
1885 }
1886
1887 // Install newly created mark bitMap as "prev".
1888 swapMarkBitMaps();
1889
1890 g1h->reset_gc_time_stamp();
1891
1892 // Note end of marking in all heap regions.
1893 G1ParNoteEndTask g1_par_note_end_task(g1h, &_cleanup_list);
1894 if (G1CollectedHeap::use_parallel_gc_threads()) {
1895 g1h->set_par_threads((int)n_workers);
1896 g1h->workers()->run_task(&g1_par_note_end_task);
1897 g1h->set_par_threads(0);
1898
1899 assert(g1h->check_heap_region_claim_values(HeapRegion::NoteEndClaimValue),
1900 "sanity check");
1901 } else {
1902 g1_par_note_end_task.work(0);
1903 }
1904 g1h->check_gc_time_stamps();
1905
1906 if (!cleanup_list_is_empty()) {
1907 // The cleanup list is not empty, so we'll have to process it
1908 // concurrently. Notify anyone else that might be wanting free
1909 // regions that there will be more free regions coming soon.
1910 g1h->set_free_regions_coming();
1911 }
1912
1913 // call below, since it affects the metric by which we sort the heap
1914 // regions.
1915 if (G1ScrubRemSets) {
1916 double rs_scrub_start = os::elapsedTime();
1917 G1ParScrubRemSetTask g1_par_scrub_rs_task(g1h, &_region_bm, &_card_bm);
1918 if (G1CollectedHeap::use_parallel_gc_threads()) {
1919 g1h->set_par_threads((int)n_workers);
1920 g1h->workers()->run_task(&g1_par_scrub_rs_task);
1921 g1h->set_par_threads(0);
1922
1923 assert(g1h->check_heap_region_claim_values(
1924 HeapRegion::ScrubRemSetClaimValue),
1925 "sanity check");
1926 } else {
1927 g1_par_scrub_rs_task.work(0);
1928 }
1929
1930 double rs_scrub_end = os::elapsedTime();
1931 double this_rs_scrub_time = (rs_scrub_end - rs_scrub_start);
1932 _total_rs_scrub_time += this_rs_scrub_time;
1933 }
1934
1935 // this will also free any regions totally full of garbage objects,
1936 // and sort the regions.
1937 g1h->g1_policy()->record_concurrent_mark_cleanup_end((int)n_workers);
1938
1939 // Statistics.
1940 double end = os::elapsedTime();
1941 _cleanup_times.add((end - start) * 1000.0);
1942
1943 if (G1Log::fine()) {
1944 g1h->print_size_transition(gclog_or_tty,
1945 start_used_bytes,
1946 g1h->used(),
1947 g1h->capacity());
1948 }
1949
1950 // Clean up will have freed any regions completely full of garbage.
1951 // Update the soft reference policy with the new heap occupancy.
1952 Universe::update_heap_info_at_gc();
1953
1954 // We need to make this be a "collection" so any collection pause that
1955 // races with it goes around and waits for completeCleanup to finish.
1956 g1h->increment_total_collections();
1957
1958 // We reclaimed old regions so we should calculate the sizes to make
1959 // sure we update the old gen/space data.
1960 g1h->g1mm()->update_sizes();
1961
1962 if (VerifyDuringGC) {
1963 HandleMark hm; // handle scope
1964 gclog_or_tty->print(" VerifyDuringGC:(after)");
1965 Universe::heap()->prepare_for_verify();
1966 Universe::verify(/* silent */ false,
1967 /* option */ VerifyOption_G1UsePrevMarking);
1968 }
1969
1970 g1h->verify_region_sets_optional();
1971 }
1972
1973 void ConcurrentMark::completeCleanup() {
1974 if (has_aborted()) return;
1975
1976 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1977
1978 _cleanup_list.verify_optional();
1979 FreeRegionList tmp_free_list("Tmp Free List");
1980
1981 if (G1ConcRegionFreeingVerbose) {
1982 gclog_or_tty->print_cr("G1ConcRegionFreeing [complete cleanup] : "
1983 "cleanup list has %u entries",
1984 _cleanup_list.length());
1985 }
1986
1987 // Noone else should be accessing the _cleanup_list at this point,
1988 // so it's not necessary to take any locks
1989 while (!_cleanup_list.is_empty()) {
1990 HeapRegion* hr = _cleanup_list.remove_head();
1991 assert(hr != NULL, "the list was not empty");
1992 hr->par_clear();
1993 tmp_free_list.add_as_tail(hr);
1994
1995 // Instead of adding one region at a time to the secondary_free_list,
1996 // we accumulate them in the local list and move them a few at a
1997 // time. This also cuts down on the number of notify_all() calls
1998 // we do during this process. We'll also append the local list when
1999 // _cleanup_list is empty (which means we just removed the last
2000 // region from the _cleanup_list).
2001 if ((tmp_free_list.length() % G1SecondaryFreeListAppendLength == 0) ||
2002 _cleanup_list.is_empty()) {
2003 if (G1ConcRegionFreeingVerbose) {
2004 gclog_or_tty->print_cr("G1ConcRegionFreeing [complete cleanup] : "
2005 "appending %u entries to the secondary_free_list, "
2006 "cleanup list still has %u entries",
2007 tmp_free_list.length(),
2008 _cleanup_list.length());
2009 }
2010
2011 {
2012 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
2013 g1h->secondary_free_list_add_as_tail(&tmp_free_list);
2014 SecondaryFreeList_lock->notify_all();
2015 }
2016
2017 if (G1StressConcRegionFreeing) {
2018 for (uintx i = 0; i < G1StressConcRegionFreeingDelayMillis; ++i) {
2019 os::sleep(Thread::current(), (jlong) 1, false);
2020 }
2021 }
2022 }
2023 }
2024 assert(tmp_free_list.is_empty(), "post-condition");
2025 }
2026
2027 // Support closures for reference procssing in G1
2028
2029 bool G1CMIsAliveClosure::do_object_b(oop obj) {
2030 HeapWord* addr = (HeapWord*)obj;
2031 return addr != NULL &&
2032 (!_g1->is_in_g1_reserved(addr) || !_g1->is_obj_ill(obj));
2033 }
2034
2035 class G1CMKeepAliveClosure: public ExtendedOopClosure {
2036 G1CollectedHeap* _g1;
2037 ConcurrentMark* _cm;
2038 public:
2039 G1CMKeepAliveClosure(G1CollectedHeap* g1, ConcurrentMark* cm) :
2040 _g1(g1), _cm(cm) {
2041 assert(Thread::current()->is_VM_thread(), "otherwise fix worker id");
2042 }
2043
2044 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
2045 virtual void do_oop( oop* p) { do_oop_work(p); }
2046
2047 template <class T> void do_oop_work(T* p) {
2048 oop obj = oopDesc::load_decode_heap_oop(p);
2049 HeapWord* addr = (HeapWord*)obj;
2050
2051 if (_cm->verbose_high()) {
2052 gclog_or_tty->print_cr("\t[0] we're looking at location "
2053 "*"PTR_FORMAT" = "PTR_FORMAT,
2054 p, (void*) obj);
2055 }
2056
2057 if (_g1->is_in_g1_reserved(addr) && _g1->is_obj_ill(obj)) {
2058 _cm->mark_and_count(obj);
2059 _cm->mark_stack_push(obj);
2060 }
2061 }
2062 };
2063
2064 class G1CMDrainMarkingStackClosure: public VoidClosure {
2065 ConcurrentMark* _cm;
2066 CMMarkStack* _markStack;
2067 G1CMKeepAliveClosure* _oopClosure;
2068 public:
2069 G1CMDrainMarkingStackClosure(ConcurrentMark* cm, CMMarkStack* markStack,
2070 G1CMKeepAliveClosure* oopClosure) :
2071 _cm(cm),
2072 _markStack(markStack),
2073 _oopClosure(oopClosure) { }
2074
2075 void do_void() {
2076 _markStack->drain(_oopClosure, _cm->nextMarkBitMap(), false);
2077 }
2078 };
2079
2080 // 'Keep Alive' closure used by parallel reference processing.
2081 // An instance of this closure is used in the parallel reference processing
2082 // code rather than an instance of G1CMKeepAliveClosure. We could have used
2083 // the G1CMKeepAliveClosure as it is MT-safe. Also reference objects are
2084 // placed on to discovered ref lists once so we can mark and push with no
2085 // need to check whether the object has already been marked. Using the
2086 // G1CMKeepAliveClosure would mean, however, having all the worker threads
2087 // operating on the global mark stack. This means that an individual
2088 // worker would be doing lock-free pushes while it processes its own
2089 // discovered ref list followed by drain call. If the discovered ref lists
2090 // are unbalanced then this could cause interference with the other
2091 // workers. Using a CMTask (and its embedded local data structures)
2092 // avoids that potential interference.
2093 class G1CMParKeepAliveAndDrainClosure: public OopClosure {
2094 ConcurrentMark* _cm;
2095 CMTask* _task;
2096 int _ref_counter_limit;
2097 int _ref_counter;
2098 public:
2099 G1CMParKeepAliveAndDrainClosure(ConcurrentMark* cm, CMTask* task) :
2100 _cm(cm), _task(task),
2101 _ref_counter_limit(G1RefProcDrainInterval) {
2102 assert(_ref_counter_limit > 0, "sanity");
2103 _ref_counter = _ref_counter_limit;
2104 }
2105
2106 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
2107 virtual void do_oop( oop* p) { do_oop_work(p); }
2108
2109 template <class T> void do_oop_work(T* p) {
2110 if (!_cm->has_overflown()) {
2111 oop obj = oopDesc::load_decode_heap_oop(p);
2112 if (_cm->verbose_high()) {
2113 gclog_or_tty->print_cr("\t[%d] we're looking at location "
2114 "*"PTR_FORMAT" = "PTR_FORMAT,
2115 _task->task_id(), p, (void*) obj);
2116 }
2117
2118 _task->deal_with_reference(obj);
2119 _ref_counter--;
2120
2121 if (_ref_counter == 0) {
2122 // We have dealt with _ref_counter_limit references, pushing them and objects
2123 // reachable from them on to the local stack (and possibly the global stack).
2124 // Call do_marking_step() to process these entries. We call the routine in a
2125 // loop, which we'll exit if there's nothing more to do (i.e. we're done
2126 // with the entries that we've pushed as a result of the deal_with_reference
2127 // calls above) or we overflow.
2128 // Note: CMTask::do_marking_step() can set the CMTask::has_aborted() flag
2129 // while there may still be some work to do. (See the comment at the
2130 // beginning of CMTask::do_marking_step() for those conditions - one of which
2131 // is reaching the specified time target.) It is only when
2132 // CMTask::do_marking_step() returns without setting the has_aborted() flag
2133 // that the marking has completed.
2134 do {
2135 double mark_step_duration_ms = G1ConcMarkStepDurationMillis;
2136 _task->do_marking_step(mark_step_duration_ms,
2137 false /* do_stealing */,
2138 false /* do_termination */);
2139 } while (_task->has_aborted() && !_cm->has_overflown());
2140 _ref_counter = _ref_counter_limit;
2141 }
2142 } else {
2143 if (_cm->verbose_high()) {
2144 gclog_or_tty->print_cr("\t[%d] CM Overflow", _task->task_id());
2145 }
2146 }
2147 }
2148 };
2149
2150 class G1CMParDrainMarkingStackClosure: public VoidClosure {
2151 ConcurrentMark* _cm;
2152 CMTask* _task;
2153 public:
2154 G1CMParDrainMarkingStackClosure(ConcurrentMark* cm, CMTask* task) :
2155 _cm(cm), _task(task) { }
2156
2157 void do_void() {
2158 do {
2159 if (_cm->verbose_high()) {
2160 gclog_or_tty->print_cr("\t[%d] Drain: Calling do marking_step",
2161 _task->task_id());
2162 }
2163
2164 // We call CMTask::do_marking_step() to completely drain the local and
2165 // global marking stacks. The routine is called in a loop, which we'll
2166 // exit if there's nothing more to do (i.e. we'completely drained the
2167 // entries that were pushed as a result of applying the
2168 // G1CMParKeepAliveAndDrainClosure to the entries on the discovered ref
2169 // lists above) or we overflow the global marking stack.
2170 // Note: CMTask::do_marking_step() can set the CMTask::has_aborted() flag
2171 // while there may still be some work to do. (See the comment at the
2172 // beginning of CMTask::do_marking_step() for those conditions - one of which
2173 // is reaching the specified time target.) It is only when
2174 // CMTask::do_marking_step() returns without setting the has_aborted() flag
2175 // that the marking has completed.
2176
2177 _task->do_marking_step(1000000000.0 /* something very large */,
2178 true /* do_stealing */,
2179 true /* do_termination */);
2180 } while (_task->has_aborted() && !_cm->has_overflown());
2181 }
2182 };
2183
2184 // Implementation of AbstractRefProcTaskExecutor for parallel
2185 // reference processing at the end of G1 concurrent marking
2186
2187 class G1CMRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
2188 private:
2189 G1CollectedHeap* _g1h;
2190 ConcurrentMark* _cm;
2191 WorkGang* _workers;
2192 int _active_workers;
2193
2194 public:
2195 G1CMRefProcTaskExecutor(G1CollectedHeap* g1h,
2196 ConcurrentMark* cm,
2197 WorkGang* workers,
2198 int n_workers) :
2199 _g1h(g1h), _cm(cm),
2200 _workers(workers), _active_workers(n_workers) { }
2201
2202 // Executes the given task using concurrent marking worker threads.
2203 virtual void execute(ProcessTask& task);
2204 virtual void execute(EnqueueTask& task);
2205 };
2206
2207 class G1CMRefProcTaskProxy: public AbstractGangTask {
2208 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
2209 ProcessTask& _proc_task;
2210 G1CollectedHeap* _g1h;
2211 ConcurrentMark* _cm;
2212
2213 public:
2214 G1CMRefProcTaskProxy(ProcessTask& proc_task,
2215 G1CollectedHeap* g1h,
2216 ConcurrentMark* cm) :
2217 AbstractGangTask("Process reference objects in parallel"),
2218 _proc_task(proc_task), _g1h(g1h), _cm(cm) { }
2219
2220 virtual void work(uint worker_id) {
2221 CMTask* marking_task = _cm->task(worker_id);
2222 G1CMIsAliveClosure g1_is_alive(_g1h);
2223 G1CMParKeepAliveAndDrainClosure g1_par_keep_alive(_cm, marking_task);
2224 G1CMParDrainMarkingStackClosure g1_par_drain(_cm, marking_task);
2225
2226 _proc_task.work(worker_id, g1_is_alive, g1_par_keep_alive, g1_par_drain);
2227 }
2228 };
2229
2230 void G1CMRefProcTaskExecutor::execute(ProcessTask& proc_task) {
2231 assert(_workers != NULL, "Need parallel worker threads.");
2232
2233 G1CMRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _cm);
2234
2235 // We need to reset the phase for each task execution so that
2236 // the termination protocol of CMTask::do_marking_step works.
2237 _cm->set_phase(_active_workers, false /* concurrent */);
2238 _g1h->set_par_threads(_active_workers);
2239 _workers->run_task(&proc_task_proxy);
2240 _g1h->set_par_threads(0);
2241 }
2242
2243 class G1CMRefEnqueueTaskProxy: public AbstractGangTask {
2244 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
2245 EnqueueTask& _enq_task;
2246
2247 public:
2248 G1CMRefEnqueueTaskProxy(EnqueueTask& enq_task) :
2249 AbstractGangTask("Enqueue reference objects in parallel"),
2250 _enq_task(enq_task) { }
2251
2252 virtual void work(uint worker_id) {
2253 _enq_task.work(worker_id);
2254 }
2255 };
2256
2257 void G1CMRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
2258 assert(_workers != NULL, "Need parallel worker threads.");
2259
2260 G1CMRefEnqueueTaskProxy enq_task_proxy(enq_task);
2261
2262 _g1h->set_par_threads(_active_workers);
2263 _workers->run_task(&enq_task_proxy);
2264 _g1h->set_par_threads(0);
2265 }
2266
2267 void ConcurrentMark::weakRefsWork(bool clear_all_soft_refs) {
2268 ResourceMark rm;
2269 HandleMark hm;
2270
2271 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2272
2273 // Is alive closure.
2274 G1CMIsAliveClosure g1_is_alive(g1h);
2275
2276 // Inner scope to exclude the cleaning of the string and symbol
2277 // tables from the displayed time.
2278 {
2279 if (G1Log::finer()) {
2280 gclog_or_tty->put(' ');
2281 }
2282 TraceTime t("GC ref-proc", G1Log::finer(), false, gclog_or_tty);
2283
2284 ReferenceProcessor* rp = g1h->ref_processor_cm();
2285
2286 // See the comment in G1CollectedHeap::ref_processing_init()
2287 // about how reference processing currently works in G1.
2288
2289 // Process weak references.
2290 rp->setup_policy(clear_all_soft_refs);
2291 assert(_markStack.isEmpty(), "mark stack should be empty");
2292
2293 G1CMKeepAliveClosure g1_keep_alive(g1h, this);
2294 G1CMDrainMarkingStackClosure
2295 g1_drain_mark_stack(this, &_markStack, &g1_keep_alive);
2296
2297 // We use the work gang from the G1CollectedHeap and we utilize all
2298 // the worker threads.
2299 uint active_workers = g1h->workers() ? g1h->workers()->active_workers() : 1U;
2300 active_workers = MAX2(MIN2(active_workers, _max_task_num), 1U);
2301
2302 G1CMRefProcTaskExecutor par_task_executor(g1h, this,
2303 g1h->workers(), active_workers);
2304
2305 if (rp->processing_is_mt()) {
2306 // Set the degree of MT here. If the discovery is done MT, there
2307 // may have been a different number of threads doing the discovery
2308 // and a different number of discovered lists may have Ref objects.
2309 // That is OK as long as the Reference lists are balanced (see
2310 // balance_all_queues() and balance_queues()).
2311 rp->set_active_mt_degree(active_workers);
2312
2313 rp->process_discovered_references(&g1_is_alive,
2314 &g1_keep_alive,
2315 &g1_drain_mark_stack,
2316 &par_task_executor);
2317
2318 // The work routines of the parallel keep_alive and drain_marking_stack
2319 // will set the has_overflown flag if we overflow the global marking
2320 // stack.
2321 } else {
2322 rp->process_discovered_references(&g1_is_alive,
2323 &g1_keep_alive,
2324 &g1_drain_mark_stack,
2325 NULL);
2326 }
2327
2328 assert(_markStack.overflow() || _markStack.isEmpty(),
2329 "mark stack should be empty (unless it overflowed)");
2330 if (_markStack.overflow()) {
2331 // Should have been done already when we tried to push an
2332 // entry on to the global mark stack. But let's do it again.
2333 set_has_overflown();
2334 }
2335
2336 if (rp->processing_is_mt()) {
2337 assert(rp->num_q() == active_workers, "why not");
2338 rp->enqueue_discovered_references(&par_task_executor);
2339 } else {
2340 rp->enqueue_discovered_references();
2341 }
2342
2343 rp->verify_no_references_recorded();
2344 assert(!rp->discovery_enabled(), "Post condition");
2345 }
2346
2347 // Now clean up stale oops in StringTable
2348 StringTable::unlink(&g1_is_alive);
2349 // Clean up unreferenced symbols in symbol table.
2350 SymbolTable::unlink();
2351 }
2352
2353 void ConcurrentMark::swapMarkBitMaps() {
2354 CMBitMapRO* temp = _prevMarkBitMap;
2355 _prevMarkBitMap = (CMBitMapRO*)_nextMarkBitMap;
2356 _nextMarkBitMap = (CMBitMap*) temp;
2357 }
2358
2359 class CMRemarkTask: public AbstractGangTask {
2360 private:
2361 ConcurrentMark *_cm;
2362
2363 public:
2364 void work(uint worker_id) {
2365 // Since all available tasks are actually started, we should
2366 // only proceed if we're supposed to be actived.
2367 if (worker_id < _cm->active_tasks()) {
2368 CMTask* task = _cm->task(worker_id);
2369 task->record_start_time();
2370 do {
2371 task->do_marking_step(1000000000.0 /* something very large */,
2372 true /* do_stealing */,
2373 true /* do_termination */);
2374 } while (task->has_aborted() && !_cm->has_overflown());
2375 // If we overflow, then we do not want to restart. We instead
2376 // want to abort remark and do concurrent marking again.
2377 task->record_end_time();
2378 }
2379 }
2380
2381 CMRemarkTask(ConcurrentMark* cm, int active_workers) :
2382 AbstractGangTask("Par Remark"), _cm(cm) {
2383 _cm->terminator()->reset_for_reuse(active_workers);
2384 }
2385 };
2386
2387 void ConcurrentMark::checkpointRootsFinalWork() {
2388 ResourceMark rm;
2389 HandleMark hm;
2390 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2391
2392 g1h->ensure_parsability(false);
2393
2394 if (G1CollectedHeap::use_parallel_gc_threads()) {
2395 G1CollectedHeap::StrongRootsScope srs(g1h);
2396 // this is remark, so we'll use up all active threads
2397 uint active_workers = g1h->workers()->active_workers();
2398 if (active_workers == 0) {
2399 assert(active_workers > 0, "Should have been set earlier");
2400 active_workers = (uint) ParallelGCThreads;
2401 g1h->workers()->set_active_workers(active_workers);
2402 }
2403 set_phase(active_workers, false /* concurrent */);
2404 // Leave _parallel_marking_threads at it's
2405 // value originally calculated in the ConcurrentMark
2406 // constructor and pass values of the active workers
2407 // through the gang in the task.
2408
2409 CMRemarkTask remarkTask(this, active_workers);
2410 g1h->set_par_threads(active_workers);
2411 g1h->workers()->run_task(&remarkTask);
2412 g1h->set_par_threads(0);
2413 } else {
2414 G1CollectedHeap::StrongRootsScope srs(g1h);
2415 // this is remark, so we'll use up all available threads
2416 uint active_workers = 1;
2417 set_phase(active_workers, false /* concurrent */);
2418
2419 CMRemarkTask remarkTask(this, active_workers);
2420 // We will start all available threads, even if we decide that the
2421 // active_workers will be fewer. The extra ones will just bail out
2422 // immediately.
2423 remarkTask.work(0);
2424 }
2425 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
2426 guarantee(satb_mq_set.completed_buffers_num() == 0, "invariant");
2427
2428 print_stats();
2429
2430 #if VERIFY_OBJS_PROCESSED
2431 if (_scan_obj_cl.objs_processed != ThreadLocalObjQueue::objs_enqueued) {
2432 gclog_or_tty->print_cr("Processed = %d, enqueued = %d.",
2433 _scan_obj_cl.objs_processed,
2434 ThreadLocalObjQueue::objs_enqueued);
2435 guarantee(_scan_obj_cl.objs_processed ==
2436 ThreadLocalObjQueue::objs_enqueued,
2437 "Different number of objs processed and enqueued.");
2438 }
2439 #endif
2440 }
2441
2442 #ifndef PRODUCT
2443
2444 class PrintReachableOopClosure: public OopClosure {
2445 private:
2446 G1CollectedHeap* _g1h;
2447 outputStream* _out;
2448 VerifyOption _vo;
2449 bool _all;
2450
2451 public:
2452 PrintReachableOopClosure(outputStream* out,
2453 VerifyOption vo,
2454 bool all) :
2455 _g1h(G1CollectedHeap::heap()),
2456 _out(out), _vo(vo), _all(all) { }
2457
2458 void do_oop(narrowOop* p) { do_oop_work(p); }
2459 void do_oop( oop* p) { do_oop_work(p); }
2460
2461 template <class T> void do_oop_work(T* p) {
2462 oop obj = oopDesc::load_decode_heap_oop(p);
2463 const char* str = NULL;
2464 const char* str2 = "";
2465
2466 if (obj == NULL) {
2467 str = "";
2468 } else if (!_g1h->is_in_g1_reserved(obj)) {
2469 str = " O";
2470 } else {
2471 HeapRegion* hr = _g1h->heap_region_containing(obj);
2472 guarantee(hr != NULL, "invariant");
2473 bool over_tams = _g1h->allocated_since_marking(obj, hr, _vo);
2474 bool marked = _g1h->is_marked(obj, _vo);
2475
2476 if (over_tams) {
2477 str = " >";
2478 if (marked) {
2479 str2 = " AND MARKED";
2480 }
2481 } else if (marked) {
2482 str = " M";
2483 } else {
2484 str = " NOT";
2485 }
2486 }
2487
2488 _out->print_cr(" "PTR_FORMAT": "PTR_FORMAT"%s%s",
2489 p, (void*) obj, str, str2);
2490 }
2491 };
2492
2493 class PrintReachableObjectClosure : public ObjectClosure {
2494 private:
2495 G1CollectedHeap* _g1h;
2496 outputStream* _out;
2497 VerifyOption _vo;
2498 bool _all;
2499 HeapRegion* _hr;
2500
2501 public:
2502 PrintReachableObjectClosure(outputStream* out,
2503 VerifyOption vo,
2504 bool all,
2505 HeapRegion* hr) :
2506 _g1h(G1CollectedHeap::heap()),
2507 _out(out), _vo(vo), _all(all), _hr(hr) { }
2508
2509 void do_object(oop o) {
2510 bool over_tams = _g1h->allocated_since_marking(o, _hr, _vo);
2511 bool marked = _g1h->is_marked(o, _vo);
2512 bool print_it = _all || over_tams || marked;
2513
2514 if (print_it) {
2515 _out->print_cr(" "PTR_FORMAT"%s",
2516 o, (over_tams) ? " >" : (marked) ? " M" : "");
2517 PrintReachableOopClosure oopCl(_out, _vo, _all);
2518 o->oop_iterate_no_header(&oopCl);
2519 }
2520 }
2521 };
2522
2523 class PrintReachableRegionClosure : public HeapRegionClosure {
2524 private:
2525 G1CollectedHeap* _g1h;
2526 outputStream* _out;
2527 VerifyOption _vo;
2528 bool _all;
2529
2530 public:
2531 bool doHeapRegion(HeapRegion* hr) {
2532 HeapWord* b = hr->bottom();
2533 HeapWord* e = hr->end();
2534 HeapWord* t = hr->top();
2535 HeapWord* p = _g1h->top_at_mark_start(hr, _vo);
2536 _out->print_cr("** ["PTR_FORMAT", "PTR_FORMAT"] top: "PTR_FORMAT" "
2537 "TAMS: "PTR_FORMAT, b, e, t, p);
2538 _out->cr();
2539
2540 HeapWord* from = b;
2541 HeapWord* to = t;
2542
2543 if (to > from) {
2544 _out->print_cr("Objects in ["PTR_FORMAT", "PTR_FORMAT"]", from, to);
2545 _out->cr();
2546 PrintReachableObjectClosure ocl(_out, _vo, _all, hr);
2547 hr->object_iterate_mem_careful(MemRegion(from, to), &ocl);
2548 _out->cr();
2549 }
2550
2551 return false;
2552 }
2553
2554 PrintReachableRegionClosure(outputStream* out,
2555 VerifyOption vo,
2556 bool all) :
2557 _g1h(G1CollectedHeap::heap()), _out(out), _vo(vo), _all(all) { }
2558 };
2559
2560 void ConcurrentMark::print_reachable(const char* str,
2561 VerifyOption vo,
2562 bool all) {
2563 gclog_or_tty->cr();
2564 gclog_or_tty->print_cr("== Doing heap dump... ");
2565
2566 if (G1PrintReachableBaseFile == NULL) {
2567 gclog_or_tty->print_cr(" #### error: no base file defined");
2568 return;
2569 }
2570
2571 if (strlen(G1PrintReachableBaseFile) + 1 + strlen(str) >
2572 (JVM_MAXPATHLEN - 1)) {
2573 gclog_or_tty->print_cr(" #### error: file name too long");
2574 return;
2575 }
2576
2577 char file_name[JVM_MAXPATHLEN];
2578 sprintf(file_name, "%s.%s", G1PrintReachableBaseFile, str);
2579 gclog_or_tty->print_cr(" dumping to file %s", file_name);
2580
2581 fileStream fout(file_name);
2582 if (!fout.is_open()) {
2583 gclog_or_tty->print_cr(" #### error: could not open file");
2584 return;
2585 }
2586
2587 outputStream* out = &fout;
2588 out->print_cr("-- USING %s", _g1h->top_at_mark_start_str(vo));
2589 out->cr();
2590
2591 out->print_cr("--- ITERATING OVER REGIONS");
2592 out->cr();
2593 PrintReachableRegionClosure rcl(out, vo, all);
2594 _g1h->heap_region_iterate(&rcl);
2595 out->cr();
2596
2597 gclog_or_tty->print_cr(" done");
2598 gclog_or_tty->flush();
2599 }
2600
2601 #endif // PRODUCT
2602
2603 void ConcurrentMark::clearRangePrevBitmap(MemRegion mr) {
2604 // Note we are overriding the read-only view of the prev map here, via
2605 // the cast.
2606 ((CMBitMap*)_prevMarkBitMap)->clearRange(mr);
2607 }
2608
2609 void ConcurrentMark::clearRangeNextBitmap(MemRegion mr) {
2610 _nextMarkBitMap->clearRange(mr);
2611 }
2612
2613 void ConcurrentMark::clearRangeBothBitmaps(MemRegion mr) {
2614 clearRangePrevBitmap(mr);
2615 clearRangeNextBitmap(mr);
2616 }
2617
2618 HeapRegion*
2619 ConcurrentMark::claim_region(int task_num) {
2620 // "checkpoint" the finger
2621 HeapWord* finger = _finger;
2622
2623 // _heap_end will not change underneath our feet; it only changes at
2624 // yield points.
2625 while (finger < _heap_end) {
2626 assert(_g1h->is_in_g1_reserved(finger), "invariant");
2627
2628 // Note on how this code handles humongous regions. In the
2629 // normal case the finger will reach the start of a "starts
2630 // humongous" (SH) region. Its end will either be the end of the
2631 // last "continues humongous" (CH) region in the sequence, or the
2632 // standard end of the SH region (if the SH is the only region in
2633 // the sequence). That way claim_region() will skip over the CH
2634 // regions. However, there is a subtle race between a CM thread
2635 // executing this method and a mutator thread doing a humongous
2636 // object allocation. The two are not mutually exclusive as the CM
2637 // thread does not need to hold the Heap_lock when it gets
2638 // here. So there is a chance that claim_region() will come across
2639 // a free region that's in the progress of becoming a SH or a CH
2640 // region. In the former case, it will either
2641 // a) Miss the update to the region's end, in which case it will
2642 // visit every subsequent CH region, will find their bitmaps
2643 // empty, and do nothing, or
2644 // b) Will observe the update of the region's end (in which case
2645 // it will skip the subsequent CH regions).
2646 // If it comes across a region that suddenly becomes CH, the
2647 // scenario will be similar to b). So, the race between
2648 // claim_region() and a humongous object allocation might force us
2649 // to do a bit of unnecessary work (due to some unnecessary bitmap
2650 // iterations) but it should not introduce and correctness issues.
2651 HeapRegion* curr_region = _g1h->heap_region_containing_raw(finger);
2652 HeapWord* bottom = curr_region->bottom();
2653 HeapWord* end = curr_region->end();
2654 HeapWord* limit = curr_region->next_top_at_mark_start();
2655
2656 if (verbose_low()) {
2657 gclog_or_tty->print_cr("[%d] curr_region = "PTR_FORMAT" "
2658 "["PTR_FORMAT", "PTR_FORMAT"), "
2659 "limit = "PTR_FORMAT,
2660 task_num, curr_region, bottom, end, limit);
2661 }
2662
2663 // Is the gap between reading the finger and doing the CAS too long?
2664 HeapWord* res = (HeapWord*) Atomic::cmpxchg_ptr(end, &_finger, finger);
2665 if (res == finger) {
2666 // we succeeded
2667
2668 // notice that _finger == end cannot be guaranteed here since,
2669 // someone else might have moved the finger even further
2670 assert(_finger >= end, "the finger should have moved forward");
2671
2672 if (verbose_low()) {
2673 gclog_or_tty->print_cr("[%d] we were successful with region = "
2674 PTR_FORMAT, task_num, curr_region);
2675 }
2676
2677 if (limit > bottom) {
2678 if (verbose_low()) {
2679 gclog_or_tty->print_cr("[%d] region "PTR_FORMAT" is not empty, "
2680 "returning it ", task_num, curr_region);
2681 }
2682 return curr_region;
2683 } else {
2684 assert(limit == bottom,
2685 "the region limit should be at bottom");
2686 if (verbose_low()) {
2687 gclog_or_tty->print_cr("[%d] region "PTR_FORMAT" is empty, "
2688 "returning NULL", task_num, curr_region);
2689 }
2690 // we return NULL and the caller should try calling
2691 // claim_region() again.
2692 return NULL;
2693 }
2694 } else {
2695 assert(_finger > finger, "the finger should have moved forward");
2696 if (verbose_low()) {
2697 gclog_or_tty->print_cr("[%d] somebody else moved the finger, "
2698 "global finger = "PTR_FORMAT", "
2699 "our finger = "PTR_FORMAT,
2700 task_num, _finger, finger);
2701 }
2702
2703 // read it again
2704 finger = _finger;
2705 }
2706 }
2707
2708 return NULL;
2709 }
2710
2711 #ifndef PRODUCT
2712 enum VerifyNoCSetOopsPhase {
2713 VerifyNoCSetOopsStack,
2714 VerifyNoCSetOopsQueues,
2715 VerifyNoCSetOopsSATBCompleted,
2716 VerifyNoCSetOopsSATBThread
2717 };
2718
2719 class VerifyNoCSetOopsClosure : public OopClosure, public ObjectClosure {
2720 private:
2721 G1CollectedHeap* _g1h;
2722 VerifyNoCSetOopsPhase _phase;
2723 int _info;
2724
2725 const char* phase_str() {
2726 switch (_phase) {
2727 case VerifyNoCSetOopsStack: return "Stack";
2728 case VerifyNoCSetOopsQueues: return "Queue";
2729 case VerifyNoCSetOopsSATBCompleted: return "Completed SATB Buffers";
2730 case VerifyNoCSetOopsSATBThread: return "Thread SATB Buffers";
2731 default: ShouldNotReachHere();
2732 }
2733 return NULL;
2734 }
2735
2736 void do_object_work(oop obj) {
2737 guarantee(!_g1h->obj_in_cs(obj),
2738 err_msg("obj: "PTR_FORMAT" in CSet, phase: %s, info: %d",
2739 (void*) obj, phase_str(), _info));
2740 }
2741
2742 public:
2743 VerifyNoCSetOopsClosure() : _g1h(G1CollectedHeap::heap()) { }
2744
2745 void set_phase(VerifyNoCSetOopsPhase phase, int info = -1) {
2746 _phase = phase;
2747 _info = info;
2748 }
2749
2750 virtual void do_oop(oop* p) {
2751 oop obj = oopDesc::load_decode_heap_oop(p);
2752 do_object_work(obj);
2753 }
2754
2755 virtual void do_oop(narrowOop* p) {
2756 // We should not come across narrow oops while scanning marking
2757 // stacks and SATB buffers.
2758 ShouldNotReachHere();
2759 }
2760
2761 virtual void do_object(oop obj) {
2762 do_object_work(obj);
2763 }
2764 };
2765
2766 void ConcurrentMark::verify_no_cset_oops(bool verify_stacks,
2767 bool verify_enqueued_buffers,
2768 bool verify_thread_buffers,
2769 bool verify_fingers) {
2770 assert(SafepointSynchronize::is_at_safepoint(), "should be at a safepoint");
2771 if (!G1CollectedHeap::heap()->mark_in_progress()) {
2772 return;
2773 }
2774
2775 VerifyNoCSetOopsClosure cl;
2776
2777 if (verify_stacks) {
2778 // Verify entries on the global mark stack
2779 cl.set_phase(VerifyNoCSetOopsStack);
2780 _markStack.oops_do(&cl);
2781
2782 // Verify entries on the task queues
2783 for (int i = 0; i < (int) _max_task_num; i += 1) {
2784 cl.set_phase(VerifyNoCSetOopsQueues, i);
2785 OopTaskQueue* queue = _task_queues->queue(i);
2786 queue->oops_do(&cl);
2787 }
2788 }
2789
2790 SATBMarkQueueSet& satb_qs = JavaThread::satb_mark_queue_set();
2791
2792 // Verify entries on the enqueued SATB buffers
2793 if (verify_enqueued_buffers) {
2794 cl.set_phase(VerifyNoCSetOopsSATBCompleted);
2795 satb_qs.iterate_completed_buffers_read_only(&cl);
2796 }
2797
2798 // Verify entries on the per-thread SATB buffers
2799 if (verify_thread_buffers) {
2800 cl.set_phase(VerifyNoCSetOopsSATBThread);
2801 satb_qs.iterate_thread_buffers_read_only(&cl);
2802 }
2803
2804 if (verify_fingers) {
2805 // Verify the global finger
2806 HeapWord* global_finger = finger();
2807 if (global_finger != NULL && global_finger < _heap_end) {
2808 // The global finger always points to a heap region boundary. We
2809 // use heap_region_containing_raw() to get the containing region
2810 // given that the global finger could be pointing to a free region
2811 // which subsequently becomes continues humongous. If that
2812 // happens, heap_region_containing() will return the bottom of the
2813 // corresponding starts humongous region and the check below will
2814 // not hold any more.
2815 HeapRegion* global_hr = _g1h->heap_region_containing_raw(global_finger);
2816 guarantee(global_finger == global_hr->bottom(),
2817 err_msg("global finger: "PTR_FORMAT" region: "HR_FORMAT,
2818 global_finger, HR_FORMAT_PARAMS(global_hr)));
2819 }
2820
2821 // Verify the task fingers
2822 assert(parallel_marking_threads() <= _max_task_num, "sanity");
2823 for (int i = 0; i < (int) parallel_marking_threads(); i += 1) {
2824 CMTask* task = _tasks[i];
2825 HeapWord* task_finger = task->finger();
2826 if (task_finger != NULL && task_finger < _heap_end) {
2827 // See above note on the global finger verification.
2828 HeapRegion* task_hr = _g1h->heap_region_containing_raw(task_finger);
2829 guarantee(task_finger == task_hr->bottom() ||
2830 !task_hr->in_collection_set(),
2831 err_msg("task finger: "PTR_FORMAT" region: "HR_FORMAT,
2832 task_finger, HR_FORMAT_PARAMS(task_hr)));
2833 }
2834 }
2835 }
2836 }
2837 #endif // PRODUCT
2838
2839 void ConcurrentMark::clear_marking_state(bool clear_overflow) {
2840 _markStack.setEmpty();
2841 _markStack.clear_overflow();
2842 if (clear_overflow) {
2843 clear_has_overflown();
2844 } else {
2845 assert(has_overflown(), "pre-condition");
2846 }
2847 _finger = _heap_start;
2848
2849 for (int i = 0; i < (int)_max_task_num; ++i) {
2850 OopTaskQueue* queue = _task_queues->queue(i);
2851 queue->set_empty();
2852 }
2853 }
2854
2855 // Aggregate the counting data that was constructed concurrently
2856 // with marking.
2857 class AggregateCountDataHRClosure: public HeapRegionClosure {
2858 G1CollectedHeap* _g1h;
2859 ConcurrentMark* _cm;
2860 CardTableModRefBS* _ct_bs;
2861 BitMap* _cm_card_bm;
2862 size_t _max_task_num;
2863
2864 public:
2865 AggregateCountDataHRClosure(G1CollectedHeap* g1h,
2866 BitMap* cm_card_bm,
2867 size_t max_task_num) :
2868 _g1h(g1h), _cm(g1h->concurrent_mark()),
2869 _ct_bs((CardTableModRefBS*) (g1h->barrier_set())),
2870 _cm_card_bm(cm_card_bm), _max_task_num(max_task_num) { }
2871
2872 bool doHeapRegion(HeapRegion* hr) {
2873 if (hr->continuesHumongous()) {
2874 // We will ignore these here and process them when their
2875 // associated "starts humongous" region is processed.
2876 // Note that we cannot rely on their associated
2877 // "starts humongous" region to have their bit set to 1
2878 // since, due to the region chunking in the parallel region
2879 // iteration, a "continues humongous" region might be visited
2880 // before its associated "starts humongous".
2881 return false;
2882 }
2883
2884 HeapWord* start = hr->bottom();
2885 HeapWord* limit = hr->next_top_at_mark_start();
2886 HeapWord* end = hr->end();
2887
2888 assert(start <= limit && limit <= hr->top() && hr->top() <= hr->end(),
2889 err_msg("Preconditions not met - "
2890 "start: "PTR_FORMAT", limit: "PTR_FORMAT", "
2891 "top: "PTR_FORMAT", end: "PTR_FORMAT,
2892 start, limit, hr->top(), hr->end()));
2893
2894 assert(hr->next_marked_bytes() == 0, "Precondition");
2895
2896 if (start == limit) {
2897 // NTAMS of this region has not been set so nothing to do.
2898 return false;
2899 }
2900
2901 // 'start' should be in the heap.
2902 assert(_g1h->is_in_g1_reserved(start) && _ct_bs->is_card_aligned(start), "sanity");
2903 // 'end' *may* be outside the heap (if hr is the last region)
2904 assert(!_g1h->is_in_g1_reserved(end) || _ct_bs->is_card_aligned(end), "sanity");
2905
2906 BitMap::idx_t start_idx = _cm->card_bitmap_index_for(start);
2907 BitMap::idx_t limit_idx = _cm->card_bitmap_index_for(limit);
2908 BitMap::idx_t end_idx = _cm->card_bitmap_index_for(end);
2909
2910 // If ntams is not card aligned then we bump card bitmap index
2911 // for limit so that we get the all the cards spanned by
2912 // the object ending at ntams.
2913 // Note: if this is the last region in the heap then ntams
2914 // *may* be outside the heap and limit_idx will correspond
2915 // to a card that is also outside the heap.
2916 if (_g1h->is_in_g1_reserved(limit) && !_ct_bs->is_card_aligned(limit)) {
2917 limit_idx += 1;
2918 }
2919
2920 assert(limit_idx <= end_idx, "or else use atomics");
2921
2922 // Aggregate the "stripe" in the count data associated with hr.
2923 uint hrs_index = hr->hrs_index();
2924 size_t marked_bytes = 0;
2925
2926 for (int i = 0; (size_t)i < _max_task_num; i += 1) {
2927 size_t* marked_bytes_array = _cm->count_marked_bytes_array_for(i);
2928 BitMap* task_card_bm = _cm->count_card_bitmap_for(i);
2929
2930 // Fetch the marked_bytes in this region for task i and
2931 // add it to the running total for this region.
2932 marked_bytes += marked_bytes_array[hrs_index];
2933
2934 // Now union the bitmaps[0,max_task_num)[start_idx..limit_idx)
2935 // into the global card bitmap.
2936 BitMap::idx_t scan_idx = task_card_bm->get_next_one_offset(start_idx, limit_idx);
2937
2938 while (scan_idx < limit_idx) {
2939 assert(task_card_bm->at(scan_idx) == true, "should be");
2940 _cm_card_bm->set_bit(scan_idx);
2941 assert(_cm_card_bm->at(scan_idx) == true, "should be");
2942
2943 // BitMap::get_next_one_offset() can handle the case when
2944 // its left_offset parameter is greater than its right_offset
2945 // parameter. It does, however, have an early exit if
2946 // left_offset == right_offset. So let's limit the value
2947 // passed in for left offset here.
2948 BitMap::idx_t next_idx = MIN2(scan_idx + 1, limit_idx);
2949 scan_idx = task_card_bm->get_next_one_offset(next_idx, limit_idx);
2950 }
2951 }
2952
2953 // Update the marked bytes for this region.
2954 hr->add_to_marked_bytes(marked_bytes);
2955
2956 // Next heap region
2957 return false;
2958 }
2959 };
2960
2961 class G1AggregateCountDataTask: public AbstractGangTask {
2962 protected:
2963 G1CollectedHeap* _g1h;
2964 ConcurrentMark* _cm;
2965 BitMap* _cm_card_bm;
2966 size_t _max_task_num;
2967 int _active_workers;
2968
2969 public:
2970 G1AggregateCountDataTask(G1CollectedHeap* g1h,
2971 ConcurrentMark* cm,
2972 BitMap* cm_card_bm,
2973 size_t max_task_num,
2974 int n_workers) :
2975 AbstractGangTask("Count Aggregation"),
2976 _g1h(g1h), _cm(cm), _cm_card_bm(cm_card_bm),
2977 _max_task_num(max_task_num),
2978 _active_workers(n_workers) { }
2979
2980 void work(uint worker_id) {
2981 AggregateCountDataHRClosure cl(_g1h, _cm_card_bm, _max_task_num);
2982
2983 if (G1CollectedHeap::use_parallel_gc_threads()) {
2984 _g1h->heap_region_par_iterate_chunked(&cl, worker_id,
2985 _active_workers,
2986 HeapRegion::AggregateCountClaimValue);
2987 } else {
2988 _g1h->heap_region_iterate(&cl);
2989 }
2990 }
2991 };
2992
2993
2994 void ConcurrentMark::aggregate_count_data() {
2995 int n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
2996 _g1h->workers()->active_workers() :
2997 1);
2998
2999 G1AggregateCountDataTask g1_par_agg_task(_g1h, this, &_card_bm,
3000 _max_task_num, n_workers);
3001
3002 if (G1CollectedHeap::use_parallel_gc_threads()) {
3003 assert(_g1h->check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3004 "sanity check");
3005 _g1h->set_par_threads(n_workers);
3006 _g1h->workers()->run_task(&g1_par_agg_task);
3007 _g1h->set_par_threads(0);
3008
3009 assert(_g1h->check_heap_region_claim_values(HeapRegion::AggregateCountClaimValue),
3010 "sanity check");
3011 _g1h->reset_heap_region_claim_values();
3012 } else {
3013 g1_par_agg_task.work(0);
3014 }
3015 }
3016
3017 // Clear the per-worker arrays used to store the per-region counting data
3018 void ConcurrentMark::clear_all_count_data() {
3019 // Clear the global card bitmap - it will be filled during
3020 // liveness count aggregation (during remark) and the
3021 // final counting task.
3022 _card_bm.clear();
3023
3024 // Clear the global region bitmap - it will be filled as part
3025 // of the final counting task.
3026 _region_bm.clear();
3027
3028 uint max_regions = _g1h->max_regions();
3029 assert(_max_task_num != 0, "unitialized");
3030
3031 for (int i = 0; (size_t) i < _max_task_num; i += 1) {
3032 BitMap* task_card_bm = count_card_bitmap_for(i);
3033 size_t* marked_bytes_array = count_marked_bytes_array_for(i);
3034
3035 assert(task_card_bm->size() == _card_bm.size(), "size mismatch");
3036 assert(marked_bytes_array != NULL, "uninitialized");
3037
3038 memset(marked_bytes_array, 0, (size_t) max_regions * sizeof(size_t));
3039 task_card_bm->clear();
3040 }
3041 }
3042
3043 void ConcurrentMark::print_stats() {
3044 if (verbose_stats()) {
3045 gclog_or_tty->print_cr("---------------------------------------------------------------------");
3046 for (size_t i = 0; i < _active_tasks; ++i) {
3047 _tasks[i]->print_stats();
3048 gclog_or_tty->print_cr("---------------------------------------------------------------------");
3049 }
3050 }
3051 }
3052
3053 // abandon current marking iteration due to a Full GC
3054 void ConcurrentMark::abort() {
3055 // Clear all marks to force marking thread to do nothing
3056 _nextMarkBitMap->clearAll();
3057 // Clear the liveness counting data
3058 clear_all_count_data();
3059 // Empty mark stack
3060 clear_marking_state();
3061 for (int i = 0; i < (int)_max_task_num; ++i) {
3062 _tasks[i]->clear_region_fields();
3063 }
3064 _has_aborted = true;
3065
3066 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
3067 satb_mq_set.abandon_partial_marking();
3068 // This can be called either during or outside marking, we'll read
3069 // the expected_active value from the SATB queue set.
3070 satb_mq_set.set_active_all_threads(
3071 false, /* new active value */
3072 satb_mq_set.is_active() /* expected_active */);
3073 }
3074
3075 static void print_ms_time_info(const char* prefix, const char* name,
3076 NumberSeq& ns) {
3077 gclog_or_tty->print_cr("%s%5d %12s: total time = %8.2f s (avg = %8.2f ms).",
3078 prefix, ns.num(), name, ns.sum()/1000.0, ns.avg());
3079 if (ns.num() > 0) {
3080 gclog_or_tty->print_cr("%s [std. dev = %8.2f ms, max = %8.2f ms]",
3081 prefix, ns.sd(), ns.maximum());
3082 }
3083 }
3084
3085 void ConcurrentMark::print_summary_info() {
3086 gclog_or_tty->print_cr(" Concurrent marking:");
3087 print_ms_time_info(" ", "init marks", _init_times);
3088 print_ms_time_info(" ", "remarks", _remark_times);
3089 {
3090 print_ms_time_info(" ", "final marks", _remark_mark_times);
3091 print_ms_time_info(" ", "weak refs", _remark_weak_ref_times);
3092
3093 }
3094 print_ms_time_info(" ", "cleanups", _cleanup_times);
3095 gclog_or_tty->print_cr(" Final counting total time = %8.2f s (avg = %8.2f ms).",
3096 _total_counting_time,
3097 (_cleanup_times.num() > 0 ? _total_counting_time * 1000.0 /
3098 (double)_cleanup_times.num()
3099 : 0.0));
3100 if (G1ScrubRemSets) {
3101 gclog_or_tty->print_cr(" RS scrub total time = %8.2f s (avg = %8.2f ms).",
3102 _total_rs_scrub_time,
3103 (_cleanup_times.num() > 0 ? _total_rs_scrub_time * 1000.0 /
3104 (double)_cleanup_times.num()
3105 : 0.0));
3106 }
3107 gclog_or_tty->print_cr(" Total stop_world time = %8.2f s.",
3108 (_init_times.sum() + _remark_times.sum() +
3109 _cleanup_times.sum())/1000.0);
3110 gclog_or_tty->print_cr(" Total concurrent time = %8.2f s "
3111 "(%8.2f s marking).",
3112 cmThread()->vtime_accum(),
3113 cmThread()->vtime_mark_accum());
3114 }
3115
3116 void ConcurrentMark::print_worker_threads_on(outputStream* st) const {
3117 _parallel_workers->print_worker_threads_on(st);
3118 }
3119
3120 // We take a break if someone is trying to stop the world.
3121 bool ConcurrentMark::do_yield_check(uint worker_id) {
3122 if (should_yield()) {
3123 if (worker_id == 0) {
3124 _g1h->g1_policy()->record_concurrent_pause();
3125 }
3126 cmThread()->yield();
3127 return true;
3128 } else {
3129 return false;
3130 }
3131 }
3132
3133 bool ConcurrentMark::should_yield() {
3134 return cmThread()->should_yield();
3135 }
3136
3137 bool ConcurrentMark::containing_card_is_marked(void* p) {
3138 size_t offset = pointer_delta(p, _g1h->reserved_region().start(), 1);
3139 return _card_bm.at(offset >> CardTableModRefBS::card_shift);
3140 }
3141
3142 bool ConcurrentMark::containing_cards_are_marked(void* start,
3143 void* last) {
3144 return containing_card_is_marked(start) &&
3145 containing_card_is_marked(last);
3146 }
3147
3148 #ifndef PRODUCT
3149 // for debugging purposes
3150 void ConcurrentMark::print_finger() {
3151 gclog_or_tty->print_cr("heap ["PTR_FORMAT", "PTR_FORMAT"), global finger = "PTR_FORMAT,
3152 _heap_start, _heap_end, _finger);
3153 for (int i = 0; i < (int) _max_task_num; ++i) {
3154 gclog_or_tty->print(" %d: "PTR_FORMAT, i, _tasks[i]->finger());
3155 }
3156 gclog_or_tty->print_cr("");
3157 }
3158 #endif
3159
3160 void CMTask::scan_object(oop obj) {
3161 assert(_nextMarkBitMap->isMarked((HeapWord*) obj), "invariant");
3162
3163 if (_cm->verbose_high()) {
3164 gclog_or_tty->print_cr("[%d] we're scanning object "PTR_FORMAT,
3165 _task_id, (void*) obj);
3166 }
3167
3168 size_t obj_size = obj->size();
3169 _words_scanned += obj_size;
3170
3171 obj->oop_iterate(_cm_oop_closure);
3172 statsOnly( ++_objs_scanned );
3173 check_limits();
3174 }
3175
3176 // Closure for iteration over bitmaps
3177 class CMBitMapClosure : public BitMapClosure {
3178 private:
3179 // the bitmap that is being iterated over
3180 CMBitMap* _nextMarkBitMap;
3181 ConcurrentMark* _cm;
3182 CMTask* _task;
3183
3184 public:
3185 CMBitMapClosure(CMTask *task, ConcurrentMark* cm, CMBitMap* nextMarkBitMap) :
3186 _task(task), _cm(cm), _nextMarkBitMap(nextMarkBitMap) { }
3187
3188 bool do_bit(size_t offset) {
3189 HeapWord* addr = _nextMarkBitMap->offsetToHeapWord(offset);
3190 assert(_nextMarkBitMap->isMarked(addr), "invariant");
3191 assert( addr < _cm->finger(), "invariant");
3192
3193 statsOnly( _task->increase_objs_found_on_bitmap() );
3194 assert(addr >= _task->finger(), "invariant");
3195
3196 // We move that task's local finger along.
3197 _task->move_finger_to(addr);
3198
3199 _task->scan_object(oop(addr));
3200 // we only partially drain the local queue and global stack
3201 _task->drain_local_queue(true);
3202 _task->drain_global_stack(true);
3203
3204 // if the has_aborted flag has been raised, we need to bail out of
3205 // the iteration
3206 return !_task->has_aborted();
3207 }
3208 };
3209
3210 // Closure for iterating over objects, currently only used for
3211 // processing SATB buffers.
3212 class CMObjectClosure : public ObjectClosure {
3213 private:
3214 CMTask* _task;
3215
3216 public:
3217 void do_object(oop obj) {
3218 _task->deal_with_reference(obj);
3219 }
3220
3221 CMObjectClosure(CMTask* task) : _task(task) { }
3222 };
3223
3224 G1CMOopClosure::G1CMOopClosure(G1CollectedHeap* g1h,
3225 ConcurrentMark* cm,
3226 CMTask* task)
3227 : _g1h(g1h), _cm(cm), _task(task) {
3228 assert(_ref_processor == NULL, "should be initialized to NULL");
3229
3230 if (G1UseConcMarkReferenceProcessing) {
3231 _ref_processor = g1h->ref_processor_cm();
3232 assert(_ref_processor != NULL, "should not be NULL");
3233 }
3234 }
3235
3236 void CMTask::setup_for_region(HeapRegion* hr) {
3237 // Separated the asserts so that we know which one fires.
3238 assert(hr != NULL,
3239 "claim_region() should have filtered out continues humongous regions");
3240 assert(!hr->continuesHumongous(),
3241 "claim_region() should have filtered out continues humongous regions");
3242
3243 if (_cm->verbose_low()) {
3244 gclog_or_tty->print_cr("[%d] setting up for region "PTR_FORMAT,
3245 _task_id, hr);
3246 }
3247
3248 _curr_region = hr;
3249 _finger = hr->bottom();
3250 update_region_limit();
3251 }
3252
3253 void CMTask::update_region_limit() {
3254 HeapRegion* hr = _curr_region;
3255 HeapWord* bottom = hr->bottom();
3256 HeapWord* limit = hr->next_top_at_mark_start();
3257
3258 if (limit == bottom) {
3259 if (_cm->verbose_low()) {
3260 gclog_or_tty->print_cr("[%d] found an empty region "
3261 "["PTR_FORMAT", "PTR_FORMAT")",
3262 _task_id, bottom, limit);
3263 }
3264 // The region was collected underneath our feet.
3265 // We set the finger to bottom to ensure that the bitmap
3266 // iteration that will follow this will not do anything.
3267 // (this is not a condition that holds when we set the region up,
3268 // as the region is not supposed to be empty in the first place)
3269 _finger = bottom;
3270 } else if (limit >= _region_limit) {
3271 assert(limit >= _finger, "peace of mind");
3272 } else {
3273 assert(limit < _region_limit, "only way to get here");
3274 // This can happen under some pretty unusual circumstances. An
3275 // evacuation pause empties the region underneath our feet (NTAMS
3276 // at bottom). We then do some allocation in the region (NTAMS
3277 // stays at bottom), followed by the region being used as a GC
3278 // alloc region (NTAMS will move to top() and the objects
3279 // originally below it will be grayed). All objects now marked in
3280 // the region are explicitly grayed, if below the global finger,
3281 // and we do not need in fact to scan anything else. So, we simply
3282 // set _finger to be limit to ensure that the bitmap iteration
3283 // doesn't do anything.
3284 _finger = limit;
3285 }
3286
3287 _region_limit = limit;
3288 }
3289
3290 void CMTask::giveup_current_region() {
3291 assert(_curr_region != NULL, "invariant");
3292 if (_cm->verbose_low()) {
3293 gclog_or_tty->print_cr("[%d] giving up region "PTR_FORMAT,
3294 _task_id, _curr_region);
3295 }
3296 clear_region_fields();
3297 }
3298
3299 void CMTask::clear_region_fields() {
3300 // Values for these three fields that indicate that we're not
3301 // holding on to a region.
3302 _curr_region = NULL;
3303 _finger = NULL;
3304 _region_limit = NULL;
3305 }
3306
3307 void CMTask::set_cm_oop_closure(G1CMOopClosure* cm_oop_closure) {
3308 if (cm_oop_closure == NULL) {
3309 assert(_cm_oop_closure != NULL, "invariant");
3310 } else {
3311 assert(_cm_oop_closure == NULL, "invariant");
3312 }
3313 _cm_oop_closure = cm_oop_closure;
3314 }
3315
3316 void CMTask::reset(CMBitMap* nextMarkBitMap) {
3317 guarantee(nextMarkBitMap != NULL, "invariant");
3318
3319 if (_cm->verbose_low()) {
3320 gclog_or_tty->print_cr("[%d] resetting", _task_id);
3321 }
3322
3323 _nextMarkBitMap = nextMarkBitMap;
3324 clear_region_fields();
3325
3326 _calls = 0;
3327 _elapsed_time_ms = 0.0;
3328 _termination_time_ms = 0.0;
3329 _termination_start_time_ms = 0.0;
3330
3331 #if _MARKING_STATS_
3332 _local_pushes = 0;
3333 _local_pops = 0;
3334 _local_max_size = 0;
3335 _objs_scanned = 0;
3336 _global_pushes = 0;
3337 _global_pops = 0;
3338 _global_max_size = 0;
3339 _global_transfers_to = 0;
3340 _global_transfers_from = 0;
3341 _regions_claimed = 0;
3342 _objs_found_on_bitmap = 0;
3343 _satb_buffers_processed = 0;
3344 _steal_attempts = 0;
3345 _steals = 0;
3346 _aborted = 0;
3347 _aborted_overflow = 0;
3348 _aborted_cm_aborted = 0;
3349 _aborted_yield = 0;
3350 _aborted_timed_out = 0;
3351 _aborted_satb = 0;
3352 _aborted_termination = 0;
3353 #endif // _MARKING_STATS_
3354 }
3355
3356 bool CMTask::should_exit_termination() {
3357 regular_clock_call();
3358 // This is called when we are in the termination protocol. We should
3359 // quit if, for some reason, this task wants to abort or the global
3360 // stack is not empty (this means that we can get work from it).
3361 return !_cm->mark_stack_empty() || has_aborted();
3362 }
3363
3364 void CMTask::reached_limit() {
3365 assert(_words_scanned >= _words_scanned_limit ||
3366 _refs_reached >= _refs_reached_limit ,
3367 "shouldn't have been called otherwise");
3368 regular_clock_call();
3369 }
3370
3371 void CMTask::regular_clock_call() {
3372 if (has_aborted()) return;
3373
3374 // First, we need to recalculate the words scanned and refs reached
3375 // limits for the next clock call.
3376 recalculate_limits();
3377
3378 // During the regular clock call we do the following
3379
3380 // (1) If an overflow has been flagged, then we abort.
3381 if (_cm->has_overflown()) {
3382 set_has_aborted();
3383 return;
3384 }
3385
3386 // If we are not concurrent (i.e. we're doing remark) we don't need
3387 // to check anything else. The other steps are only needed during
3388 // the concurrent marking phase.
3389 if (!concurrent()) return;
3390
3391 // (2) If marking has been aborted for Full GC, then we also abort.
3392 if (_cm->has_aborted()) {
3393 set_has_aborted();
3394 statsOnly( ++_aborted_cm_aborted );
3395 return;
3396 }
3397
3398 double curr_time_ms = os::elapsedVTime() * 1000.0;
3399
3400 // (3) If marking stats are enabled, then we update the step history.
3401 #if _MARKING_STATS_
3402 if (_words_scanned >= _words_scanned_limit) {
3403 ++_clock_due_to_scanning;
3404 }
3405 if (_refs_reached >= _refs_reached_limit) {
3406 ++_clock_due_to_marking;
3407 }
3408
3409 double last_interval_ms = curr_time_ms - _interval_start_time_ms;
3410 _interval_start_time_ms = curr_time_ms;
3411 _all_clock_intervals_ms.add(last_interval_ms);
3412
3413 if (_cm->verbose_medium()) {
3414 gclog_or_tty->print_cr("[%d] regular clock, interval = %1.2lfms, "
3415 "scanned = %d%s, refs reached = %d%s",
3416 _task_id, last_interval_ms,
3417 _words_scanned,
3418 (_words_scanned >= _words_scanned_limit) ? " (*)" : "",
3419 _refs_reached,
3420 (_refs_reached >= _refs_reached_limit) ? " (*)" : "");
3421 }
3422 #endif // _MARKING_STATS_
3423
3424 // (4) We check whether we should yield. If we have to, then we abort.
3425 if (_cm->should_yield()) {
3426 // We should yield. To do this we abort the task. The caller is
3427 // responsible for yielding.
3428 set_has_aborted();
3429 statsOnly( ++_aborted_yield );
3430 return;
3431 }
3432
3433 // (5) We check whether we've reached our time quota. If we have,
3434 // then we abort.
3435 double elapsed_time_ms = curr_time_ms - _start_time_ms;
3436 if (elapsed_time_ms > _time_target_ms) {
3437 set_has_aborted();
3438 _has_timed_out = true;
3439 statsOnly( ++_aborted_timed_out );
3440 return;
3441 }
3442
3443 // (6) Finally, we check whether there are enough completed STAB
3444 // buffers available for processing. If there are, we abort.
3445 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
3446 if (!_draining_satb_buffers && satb_mq_set.process_completed_buffers()) {
3447 if (_cm->verbose_low()) {
3448 gclog_or_tty->print_cr("[%d] aborting to deal with pending SATB buffers",
3449 _task_id);
3450 }
3451 // we do need to process SATB buffers, we'll abort and restart
3452 // the marking task to do so
3453 set_has_aborted();
3454 statsOnly( ++_aborted_satb );
3455 return;
3456 }
3457 }
3458
3459 void CMTask::recalculate_limits() {
3460 _real_words_scanned_limit = _words_scanned + words_scanned_period;
3461 _words_scanned_limit = _real_words_scanned_limit;
3462
3463 _real_refs_reached_limit = _refs_reached + refs_reached_period;
3464 _refs_reached_limit = _real_refs_reached_limit;
3465 }
3466
3467 void CMTask::decrease_limits() {
3468 // This is called when we believe that we're going to do an infrequent
3469 // operation which will increase the per byte scanned cost (i.e. move
3470 // entries to/from the global stack). It basically tries to decrease the
3471 // scanning limit so that the clock is called earlier.
3472
3473 if (_cm->verbose_medium()) {
3474 gclog_or_tty->print_cr("[%d] decreasing limits", _task_id);
3475 }
3476
3477 _words_scanned_limit = _real_words_scanned_limit -
3478 3 * words_scanned_period / 4;
3479 _refs_reached_limit = _real_refs_reached_limit -
3480 3 * refs_reached_period / 4;
3481 }
3482
3483 void CMTask::move_entries_to_global_stack() {
3484 // local array where we'll store the entries that will be popped
3485 // from the local queue
3486 oop buffer[global_stack_transfer_size];
3487
3488 int n = 0;
3489 oop obj;
3490 while (n < global_stack_transfer_size && _task_queue->pop_local(obj)) {
3491 buffer[n] = obj;
3492 ++n;
3493 }
3494
3495 if (n > 0) {
3496 // we popped at least one entry from the local queue
3497
3498 statsOnly( ++_global_transfers_to; _local_pops += n );
3499
3500 if (!_cm->mark_stack_push(buffer, n)) {
3501 if (_cm->verbose_low()) {
3502 gclog_or_tty->print_cr("[%d] aborting due to global stack overflow",
3503 _task_id);
3504 }
3505 set_has_aborted();
3506 } else {
3507 // the transfer was successful
3508
3509 if (_cm->verbose_medium()) {
3510 gclog_or_tty->print_cr("[%d] pushed %d entries to the global stack",
3511 _task_id, n);
3512 }
3513 statsOnly( int tmp_size = _cm->mark_stack_size();
3514 if (tmp_size > _global_max_size) {
3515 _global_max_size = tmp_size;
3516 }
3517 _global_pushes += n );
3518 }
3519 }
3520
3521 // this operation was quite expensive, so decrease the limits
3522 decrease_limits();
3523 }
3524
3525 void CMTask::get_entries_from_global_stack() {
3526 // local array where we'll store the entries that will be popped
3527 // from the global stack.
3528 oop buffer[global_stack_transfer_size];
3529 int n;
3530 _cm->mark_stack_pop(buffer, global_stack_transfer_size, &n);
3531 assert(n <= global_stack_transfer_size,
3532 "we should not pop more than the given limit");
3533 if (n > 0) {
3534 // yes, we did actually pop at least one entry
3535
3536 statsOnly( ++_global_transfers_from; _global_pops += n );
3537 if (_cm->verbose_medium()) {
3538 gclog_or_tty->print_cr("[%d] popped %d entries from the global stack",
3539 _task_id, n);
3540 }
3541 for (int i = 0; i < n; ++i) {
3542 bool success = _task_queue->push(buffer[i]);
3543 // We only call this when the local queue is empty or under a
3544 // given target limit. So, we do not expect this push to fail.
3545 assert(success, "invariant");
3546 }
3547
3548 statsOnly( int tmp_size = _task_queue->size();
3549 if (tmp_size > _local_max_size) {
3550 _local_max_size = tmp_size;
3551 }
3552 _local_pushes += n );
3553 }
3554
3555 // this operation was quite expensive, so decrease the limits
3556 decrease_limits();
3557 }
3558
3559 void CMTask::drain_local_queue(bool partially) {
3560 if (has_aborted()) return;
3561
3562 // Decide what the target size is, depending whether we're going to
3563 // drain it partially (so that other tasks can steal if they run out
3564 // of things to do) or totally (at the very end).
3565 size_t target_size;
3566 if (partially) {
3567 target_size = MIN2((size_t)_task_queue->max_elems()/3, GCDrainStackTargetSize);
3568 } else {
3569 target_size = 0;
3570 }
3571
3572 if (_task_queue->size() > target_size) {
3573 if (_cm->verbose_high()) {
3574 gclog_or_tty->print_cr("[%d] draining local queue, target size = %d",
3575 _task_id, target_size);
3576 }
3577
3578 oop obj;
3579 bool ret = _task_queue->pop_local(obj);
3580 while (ret) {
3581 statsOnly( ++_local_pops );
3582
3583 if (_cm->verbose_high()) {
3584 gclog_or_tty->print_cr("[%d] popped "PTR_FORMAT, _task_id,
3585 (void*) obj);
3586 }
3587
3588 assert(_g1h->is_in_g1_reserved((HeapWord*) obj), "invariant" );
3589 assert(!_g1h->is_on_master_free_list(
3590 _g1h->heap_region_containing((HeapWord*) obj)), "invariant");
3591
3592 scan_object(obj);
3593
3594 if (_task_queue->size() <= target_size || has_aborted()) {
3595 ret = false;
3596 } else {
3597 ret = _task_queue->pop_local(obj);
3598 }
3599 }
3600
3601 if (_cm->verbose_high()) {
3602 gclog_or_tty->print_cr("[%d] drained local queue, size = %d",
3603 _task_id, _task_queue->size());
3604 }
3605 }
3606 }
3607
3608 void CMTask::drain_global_stack(bool partially) {
3609 if (has_aborted()) return;
3610
3611 // We have a policy to drain the local queue before we attempt to
3612 // drain the global stack.
3613 assert(partially || _task_queue->size() == 0, "invariant");
3614
3615 // Decide what the target size is, depending whether we're going to
3616 // drain it partially (so that other tasks can steal if they run out
3617 // of things to do) or totally (at the very end). Notice that,
3618 // because we move entries from the global stack in chunks or
3619 // because another task might be doing the same, we might in fact
3620 // drop below the target. But, this is not a problem.
3621 size_t target_size;
3622 if (partially) {
3623 target_size = _cm->partial_mark_stack_size_target();
3624 } else {
3625 target_size = 0;
3626 }
3627
3628 if (_cm->mark_stack_size() > target_size) {
3629 if (_cm->verbose_low()) {
3630 gclog_or_tty->print_cr("[%d] draining global_stack, target size %d",
3631 _task_id, target_size);
3632 }
3633
3634 while (!has_aborted() && _cm->mark_stack_size() > target_size) {
3635 get_entries_from_global_stack();
3636 drain_local_queue(partially);
3637 }
3638
3639 if (_cm->verbose_low()) {
3640 gclog_or_tty->print_cr("[%d] drained global stack, size = %d",
3641 _task_id, _cm->mark_stack_size());
3642 }
3643 }
3644 }
3645
3646 // SATB Queue has several assumptions on whether to call the par or
3647 // non-par versions of the methods. this is why some of the code is
3648 // replicated. We should really get rid of the single-threaded version
3649 // of the code to simplify things.
3650 void CMTask::drain_satb_buffers() {
3651 if (has_aborted()) return;
3652
3653 // We set this so that the regular clock knows that we're in the
3654 // middle of draining buffers and doesn't set the abort flag when it
3655 // notices that SATB buffers are available for draining. It'd be
3656 // very counter productive if it did that. :-)
3657 _draining_satb_buffers = true;
3658
3659 CMObjectClosure oc(this);
3660 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
3661 if (G1CollectedHeap::use_parallel_gc_threads()) {
3662 satb_mq_set.set_par_closure(_task_id, &oc);
3663 } else {
3664 satb_mq_set.set_closure(&oc);
3665 }
3666
3667 // This keeps claiming and applying the closure to completed buffers
3668 // until we run out of buffers or we need to abort.
3669 if (G1CollectedHeap::use_parallel_gc_threads()) {
3670 while (!has_aborted() &&
3671 satb_mq_set.par_apply_closure_to_completed_buffer(_task_id)) {
3672 if (_cm->verbose_medium()) {
3673 gclog_or_tty->print_cr("[%d] processed an SATB buffer", _task_id);
3674 }
3675 statsOnly( ++_satb_buffers_processed );
3676 regular_clock_call();
3677 }
3678 } else {
3679 while (!has_aborted() &&
3680 satb_mq_set.apply_closure_to_completed_buffer()) {
3681 if (_cm->verbose_medium()) {
3682 gclog_or_tty->print_cr("[%d] processed an SATB buffer", _task_id);
3683 }
3684 statsOnly( ++_satb_buffers_processed );
3685 regular_clock_call();
3686 }
3687 }
3688
3689 if (!concurrent() && !has_aborted()) {
3690 // We should only do this during remark.
3691 if (G1CollectedHeap::use_parallel_gc_threads()) {
3692 satb_mq_set.par_iterate_closure_all_threads(_task_id);
3693 } else {
3694 satb_mq_set.iterate_closure_all_threads();
3695 }
3696 }
3697
3698 _draining_satb_buffers = false;
3699
3700 assert(has_aborted() ||
3701 concurrent() ||
3702 satb_mq_set.completed_buffers_num() == 0, "invariant");
3703
3704 if (G1CollectedHeap::use_parallel_gc_threads()) {
3705 satb_mq_set.set_par_closure(_task_id, NULL);
3706 } else {
3707 satb_mq_set.set_closure(NULL);
3708 }
3709
3710 // again, this was a potentially expensive operation, decrease the
3711 // limits to get the regular clock call early
3712 decrease_limits();
3713 }
3714
3715 void CMTask::print_stats() {
3716 gclog_or_tty->print_cr("Marking Stats, task = %d, calls = %d",
3717 _task_id, _calls);
3718 gclog_or_tty->print_cr(" Elapsed time = %1.2lfms, Termination time = %1.2lfms",
3719 _elapsed_time_ms, _termination_time_ms);
3720 gclog_or_tty->print_cr(" Step Times (cum): num = %d, avg = %1.2lfms, sd = %1.2lfms",
3721 _step_times_ms.num(), _step_times_ms.avg(),
3722 _step_times_ms.sd());
3723 gclog_or_tty->print_cr(" max = %1.2lfms, total = %1.2lfms",
3724 _step_times_ms.maximum(), _step_times_ms.sum());
3725
3726 #if _MARKING_STATS_
3727 gclog_or_tty->print_cr(" Clock Intervals (cum): num = %d, avg = %1.2lfms, sd = %1.2lfms",
3728 _all_clock_intervals_ms.num(), _all_clock_intervals_ms.avg(),
3729 _all_clock_intervals_ms.sd());
3730 gclog_or_tty->print_cr(" max = %1.2lfms, total = %1.2lfms",
3731 _all_clock_intervals_ms.maximum(),
3732 _all_clock_intervals_ms.sum());
3733 gclog_or_tty->print_cr(" Clock Causes (cum): scanning = %d, marking = %d",
3734 _clock_due_to_scanning, _clock_due_to_marking);
3735 gclog_or_tty->print_cr(" Objects: scanned = %d, found on the bitmap = %d",
3736 _objs_scanned, _objs_found_on_bitmap);
3737 gclog_or_tty->print_cr(" Local Queue: pushes = %d, pops = %d, max size = %d",
3738 _local_pushes, _local_pops, _local_max_size);
3739 gclog_or_tty->print_cr(" Global Stack: pushes = %d, pops = %d, max size = %d",
3740 _global_pushes, _global_pops, _global_max_size);
3741 gclog_or_tty->print_cr(" transfers to = %d, transfers from = %d",
3742 _global_transfers_to,_global_transfers_from);
3743 gclog_or_tty->print_cr(" Regions: claimed = %d", _regions_claimed);
3744 gclog_or_tty->print_cr(" SATB buffers: processed = %d", _satb_buffers_processed);
3745 gclog_or_tty->print_cr(" Steals: attempts = %d, successes = %d",
3746 _steal_attempts, _steals);
3747 gclog_or_tty->print_cr(" Aborted: %d, due to", _aborted);
3748 gclog_or_tty->print_cr(" overflow: %d, global abort: %d, yield: %d",
3749 _aborted_overflow, _aborted_cm_aborted, _aborted_yield);
3750 gclog_or_tty->print_cr(" time out: %d, SATB: %d, termination: %d",
3751 _aborted_timed_out, _aborted_satb, _aborted_termination);
3752 #endif // _MARKING_STATS_
3753 }
3754
3755 /*****************************************************************************
3756
3757 The do_marking_step(time_target_ms) method is the building block
3758 of the parallel marking framework. It can be called in parallel
3759 with other invocations of do_marking_step() on different tasks
3760 (but only one per task, obviously) and concurrently with the
3761 mutator threads, or during remark, hence it eliminates the need
3762 for two versions of the code. When called during remark, it will
3763 pick up from where the task left off during the concurrent marking
3764 phase. Interestingly, tasks are also claimable during evacuation
3765 pauses too, since do_marking_step() ensures that it aborts before
3766 it needs to yield.
3767
3768 The data structures that is uses to do marking work are the
3769 following:
3770
3771 (1) Marking Bitmap. If there are gray objects that appear only
3772 on the bitmap (this happens either when dealing with an overflow
3773 or when the initial marking phase has simply marked the roots
3774 and didn't push them on the stack), then tasks claim heap
3775 regions whose bitmap they then scan to find gray objects. A
3776 global finger indicates where the end of the last claimed region
3777 is. A local finger indicates how far into the region a task has
3778 scanned. The two fingers are used to determine how to gray an
3779 object (i.e. whether simply marking it is OK, as it will be
3780 visited by a task in the future, or whether it needs to be also
3781 pushed on a stack).
3782
3783 (2) Local Queue. The local queue of the task which is accessed
3784 reasonably efficiently by the task. Other tasks can steal from
3785 it when they run out of work. Throughout the marking phase, a
3786 task attempts to keep its local queue short but not totally
3787 empty, so that entries are available for stealing by other
3788 tasks. Only when there is no more work, a task will totally
3789 drain its local queue.
3790
3791 (3) Global Mark Stack. This handles local queue overflow. During
3792 marking only sets of entries are moved between it and the local
3793 queues, as access to it requires a mutex and more fine-grain
3794 interaction with it which might cause contention. If it
3795 overflows, then the marking phase should restart and iterate
3796 over the bitmap to identify gray objects. Throughout the marking
3797 phase, tasks attempt to keep the global mark stack at a small
3798 length but not totally empty, so that entries are available for
3799 popping by other tasks. Only when there is no more work, tasks
3800 will totally drain the global mark stack.
3801
3802 (4) SATB Buffer Queue. This is where completed SATB buffers are
3803 made available. Buffers are regularly removed from this queue
3804 and scanned for roots, so that the queue doesn't get too
3805 long. During remark, all completed buffers are processed, as
3806 well as the filled in parts of any uncompleted buffers.
3807
3808 The do_marking_step() method tries to abort when the time target
3809 has been reached. There are a few other cases when the
3810 do_marking_step() method also aborts:
3811
3812 (1) When the marking phase has been aborted (after a Full GC).
3813
3814 (2) When a global overflow (on the global stack) has been
3815 triggered. Before the task aborts, it will actually sync up with
3816 the other tasks to ensure that all the marking data structures
3817 (local queues, stacks, fingers etc.) are re-initialised so that
3818 when do_marking_step() completes, the marking phase can
3819 immediately restart.
3820
3821 (3) When enough completed SATB buffers are available. The
3822 do_marking_step() method only tries to drain SATB buffers right
3823 at the beginning. So, if enough buffers are available, the
3824 marking step aborts and the SATB buffers are processed at
3825 the beginning of the next invocation.
3826
3827 (4) To yield. when we have to yield then we abort and yield
3828 right at the end of do_marking_step(). This saves us from a lot
3829 of hassle as, by yielding we might allow a Full GC. If this
3830 happens then objects will be compacted underneath our feet, the
3831 heap might shrink, etc. We save checking for this by just
3832 aborting and doing the yield right at the end.
3833
3834 From the above it follows that the do_marking_step() method should
3835 be called in a loop (or, otherwise, regularly) until it completes.
3836
3837 If a marking step completes without its has_aborted() flag being
3838 true, it means it has completed the current marking phase (and
3839 also all other marking tasks have done so and have all synced up).
3840
3841 A method called regular_clock_call() is invoked "regularly" (in
3842 sub ms intervals) throughout marking. It is this clock method that
3843 checks all the abort conditions which were mentioned above and
3844 decides when the task should abort. A work-based scheme is used to
3845 trigger this clock method: when the number of object words the
3846 marking phase has scanned or the number of references the marking
3847 phase has visited reach a given limit. Additional invocations to
3848 the method clock have been planted in a few other strategic places
3849 too. The initial reason for the clock method was to avoid calling
3850 vtime too regularly, as it is quite expensive. So, once it was in
3851 place, it was natural to piggy-back all the other conditions on it
3852 too and not constantly check them throughout the code.
3853
3854 *****************************************************************************/
3855
3856 void CMTask::do_marking_step(double time_target_ms,
3857 bool do_stealing,
3858 bool do_termination) {
3859 assert(time_target_ms >= 1.0, "minimum granularity is 1ms");
3860 assert(concurrent() == _cm->concurrent(), "they should be the same");
3861
3862 G1CollectorPolicy* g1_policy = _g1h->g1_policy();
3863 assert(_task_queues != NULL, "invariant");
3864 assert(_task_queue != NULL, "invariant");
3865 assert(_task_queues->queue(_task_id) == _task_queue, "invariant");
3866
3867 assert(!_claimed,
3868 "only one thread should claim this task at any one time");
3869
3870 // OK, this doesn't safeguard again all possible scenarios, as it is
3871 // possible for two threads to set the _claimed flag at the same
3872 // time. But it is only for debugging purposes anyway and it will
3873 // catch most problems.
3874 _claimed = true;
3875
3876 _start_time_ms = os::elapsedVTime() * 1000.0;
3877 statsOnly( _interval_start_time_ms = _start_time_ms );
3878
3879 double diff_prediction_ms =
3880 g1_policy->get_new_prediction(&_marking_step_diffs_ms);
3881 _time_target_ms = time_target_ms - diff_prediction_ms;
3882
3883 // set up the variables that are used in the work-based scheme to
3884 // call the regular clock method
3885 _words_scanned = 0;
3886 _refs_reached = 0;
3887 recalculate_limits();
3888
3889 // clear all flags
3890 clear_has_aborted();
3891 _has_timed_out = false;
3892 _draining_satb_buffers = false;
3893
3894 ++_calls;
3895
3896 if (_cm->verbose_low()) {
3897 gclog_or_tty->print_cr("[%d] >>>>>>>>>> START, call = %d, "
3898 "target = %1.2lfms >>>>>>>>>>",
3899 _task_id, _calls, _time_target_ms);
3900 }
3901
3902 // Set up the bitmap and oop closures. Anything that uses them is
3903 // eventually called from this method, so it is OK to allocate these
3904 // statically.
3905 CMBitMapClosure bitmap_closure(this, _cm, _nextMarkBitMap);
3906 G1CMOopClosure cm_oop_closure(_g1h, _cm, this);
3907 set_cm_oop_closure(&cm_oop_closure);
3908
3909 if (_cm->has_overflown()) {
3910 // This can happen if the mark stack overflows during a GC pause
3911 // and this task, after a yield point, restarts. We have to abort
3912 // as we need to get into the overflow protocol which happens
3913 // right at the end of this task.
3914 set_has_aborted();
3915 }
3916
3917 // First drain any available SATB buffers. After this, we will not
3918 // look at SATB buffers before the next invocation of this method.
3919 // If enough completed SATB buffers are queued up, the regular clock
3920 // will abort this task so that it restarts.
3921 drain_satb_buffers();
3922 // ...then partially drain the local queue and the global stack
3923 drain_local_queue(true);
3924 drain_global_stack(true);
3925
3926 do {
3927 if (!has_aborted() && _curr_region != NULL) {
3928 // This means that we're already holding on to a region.
3929 assert(_finger != NULL, "if region is not NULL, then the finger "
3930 "should not be NULL either");
3931
3932 // We might have restarted this task after an evacuation pause
3933 // which might have evacuated the region we're holding on to
3934 // underneath our feet. Let's read its limit again to make sure
3935 // that we do not iterate over a region of the heap that
3936 // contains garbage (update_region_limit() will also move
3937 // _finger to the start of the region if it is found empty).
3938 update_region_limit();
3939 // We will start from _finger not from the start of the region,
3940 // as we might be restarting this task after aborting half-way
3941 // through scanning this region. In this case, _finger points to
3942 // the address where we last found a marked object. If this is a
3943 // fresh region, _finger points to start().
3944 MemRegion mr = MemRegion(_finger, _region_limit);
3945
3946 if (_cm->verbose_low()) {
3947 gclog_or_tty->print_cr("[%d] we're scanning part "
3948 "["PTR_FORMAT", "PTR_FORMAT") "
3949 "of region "PTR_FORMAT,
3950 _task_id, _finger, _region_limit, _curr_region);
3951 }
3952
3953 // Let's iterate over the bitmap of the part of the
3954 // region that is left.
3955 if (mr.is_empty() || _nextMarkBitMap->iterate(&bitmap_closure, mr)) {
3956 // We successfully completed iterating over the region. Now,
3957 // let's give up the region.
3958 giveup_current_region();
3959 regular_clock_call();
3960 } else {
3961 assert(has_aborted(), "currently the only way to do so");
3962 // The only way to abort the bitmap iteration is to return
3963 // false from the do_bit() method. However, inside the
3964 // do_bit() method we move the _finger to point to the
3965 // object currently being looked at. So, if we bail out, we
3966 // have definitely set _finger to something non-null.
3967 assert(_finger != NULL, "invariant");
3968
3969 // Region iteration was actually aborted. So now _finger
3970 // points to the address of the object we last scanned. If we
3971 // leave it there, when we restart this task, we will rescan
3972 // the object. It is easy to avoid this. We move the finger by
3973 // enough to point to the next possible object header (the
3974 // bitmap knows by how much we need to move it as it knows its
3975 // granularity).
3976 assert(_finger < _region_limit, "invariant");
3977 HeapWord* new_finger = _nextMarkBitMap->nextWord(_finger);
3978 // Check if bitmap iteration was aborted while scanning the last object
3979 if (new_finger >= _region_limit) {
3980 giveup_current_region();
3981 } else {
3982 move_finger_to(new_finger);
3983 }
3984 }
3985 }
3986 // At this point we have either completed iterating over the
3987 // region we were holding on to, or we have aborted.
3988
3989 // We then partially drain the local queue and the global stack.
3990 // (Do we really need this?)
3991 drain_local_queue(true);
3992 drain_global_stack(true);
3993
3994 // Read the note on the claim_region() method on why it might
3995 // return NULL with potentially more regions available for
3996 // claiming and why we have to check out_of_regions() to determine
3997 // whether we're done or not.
3998 while (!has_aborted() && _curr_region == NULL && !_cm->out_of_regions()) {
3999 // We are going to try to claim a new region. We should have
4000 // given up on the previous one.
4001 // Separated the asserts so that we know which one fires.
4002 assert(_curr_region == NULL, "invariant");
4003 assert(_finger == NULL, "invariant");
4004 assert(_region_limit == NULL, "invariant");
4005 if (_cm->verbose_low()) {
4006 gclog_or_tty->print_cr("[%d] trying to claim a new region", _task_id);
4007 }
4008 HeapRegion* claimed_region = _cm->claim_region(_task_id);
4009 if (claimed_region != NULL) {
4010 // Yes, we managed to claim one
4011 statsOnly( ++_regions_claimed );
4012
4013 if (_cm->verbose_low()) {
4014 gclog_or_tty->print_cr("[%d] we successfully claimed "
4015 "region "PTR_FORMAT,
4016 _task_id, claimed_region);
4017 }
4018
4019 setup_for_region(claimed_region);
4020 assert(_curr_region == claimed_region, "invariant");
4021 }
4022 // It is important to call the regular clock here. It might take
4023 // a while to claim a region if, for example, we hit a large
4024 // block of empty regions. So we need to call the regular clock
4025 // method once round the loop to make sure it's called
4026 // frequently enough.
4027 regular_clock_call();
4028 }
4029
4030 if (!has_aborted() && _curr_region == NULL) {
4031 assert(_cm->out_of_regions(),
4032 "at this point we should be out of regions");
4033 }
4034 } while ( _curr_region != NULL && !has_aborted());
4035
4036 if (!has_aborted()) {
4037 // We cannot check whether the global stack is empty, since other
4038 // tasks might be pushing objects to it concurrently.
4039 assert(_cm->out_of_regions(),
4040 "at this point we should be out of regions");
4041
4042 if (_cm->verbose_low()) {
4043 gclog_or_tty->print_cr("[%d] all regions claimed", _task_id);
4044 }
4045
4046 // Try to reduce the number of available SATB buffers so that
4047 // remark has less work to do.
4048 drain_satb_buffers();
4049 }
4050
4051 // Since we've done everything else, we can now totally drain the
4052 // local queue and global stack.
4053 drain_local_queue(false);
4054 drain_global_stack(false);
4055
4056 // Attempt at work stealing from other task's queues.
4057 if (do_stealing && !has_aborted()) {
4058 // We have not aborted. This means that we have finished all that
4059 // we could. Let's try to do some stealing...
4060
4061 // We cannot check whether the global stack is empty, since other
4062 // tasks might be pushing objects to it concurrently.
4063 assert(_cm->out_of_regions() && _task_queue->size() == 0,
4064 "only way to reach here");
4065
4066 if (_cm->verbose_low()) {
4067 gclog_or_tty->print_cr("[%d] starting to steal", _task_id);
4068 }
4069
4070 while (!has_aborted()) {
4071 oop obj;
4072 statsOnly( ++_steal_attempts );
4073
4074 if (_cm->try_stealing(_task_id, &_hash_seed, obj)) {
4075 if (_cm->verbose_medium()) {
4076 gclog_or_tty->print_cr("[%d] stolen "PTR_FORMAT" successfully",
4077 _task_id, (void*) obj);
4078 }
4079
4080 statsOnly( ++_steals );
4081
4082 assert(_nextMarkBitMap->isMarked((HeapWord*) obj),
4083 "any stolen object should be marked");
4084 scan_object(obj);
4085
4086 // And since we're towards the end, let's totally drain the
4087 // local queue and global stack.
4088 drain_local_queue(false);
4089 drain_global_stack(false);
4090 } else {
4091 break;
4092 }
4093 }
4094 }
4095
4096 // If we are about to wrap up and go into termination, check if we
4097 // should raise the overflow flag.
4098 if (do_termination && !has_aborted()) {
4099 if (_cm->force_overflow()->should_force()) {
4100 _cm->set_has_overflown();
4101 regular_clock_call();
4102 }
4103 }
4104
4105 // We still haven't aborted. Now, let's try to get into the
4106 // termination protocol.
4107 if (do_termination && !has_aborted()) {
4108 // We cannot check whether the global stack is empty, since other
4109 // tasks might be concurrently pushing objects on it.
4110 // Separated the asserts so that we know which one fires.
4111 assert(_cm->out_of_regions(), "only way to reach here");
4112 assert(_task_queue->size() == 0, "only way to reach here");
4113
4114 if (_cm->verbose_low()) {
4115 gclog_or_tty->print_cr("[%d] starting termination protocol", _task_id);
4116 }
4117
4118 _termination_start_time_ms = os::elapsedVTime() * 1000.0;
4119 // The CMTask class also extends the TerminatorTerminator class,
4120 // hence its should_exit_termination() method will also decide
4121 // whether to exit the termination protocol or not.
4122 bool finished = _cm->terminator()->offer_termination(this);
4123 double termination_end_time_ms = os::elapsedVTime() * 1000.0;
4124 _termination_time_ms +=
4125 termination_end_time_ms - _termination_start_time_ms;
4126
4127 if (finished) {
4128 // We're all done.
4129
4130 if (_task_id == 0) {
4131 // let's allow task 0 to do this
4132 if (concurrent()) {
4133 assert(_cm->concurrent_marking_in_progress(), "invariant");
4134 // we need to set this to false before the next
4135 // safepoint. This way we ensure that the marking phase
4136 // doesn't observe any more heap expansions.
4137 _cm->clear_concurrent_marking_in_progress();
4138 }
4139 }
4140
4141 // We can now guarantee that the global stack is empty, since
4142 // all other tasks have finished. We separated the guarantees so
4143 // that, if a condition is false, we can immediately find out
4144 // which one.
4145 guarantee(_cm->out_of_regions(), "only way to reach here");
4146 guarantee(_cm->mark_stack_empty(), "only way to reach here");
4147 guarantee(_task_queue->size() == 0, "only way to reach here");
4148 guarantee(!_cm->has_overflown(), "only way to reach here");
4149 guarantee(!_cm->mark_stack_overflow(), "only way to reach here");
4150
4151 if (_cm->verbose_low()) {
4152 gclog_or_tty->print_cr("[%d] all tasks terminated", _task_id);
4153 }
4154 } else {
4155 // Apparently there's more work to do. Let's abort this task. It
4156 // will restart it and we can hopefully find more things to do.
4157
4158 if (_cm->verbose_low()) {
4159 gclog_or_tty->print_cr("[%d] apparently there is more work to do",
4160 _task_id);
4161 }
4162
4163 set_has_aborted();
4164 statsOnly( ++_aborted_termination );
4165 }
4166 }
4167
4168 // Mainly for debugging purposes to make sure that a pointer to the
4169 // closure which was statically allocated in this frame doesn't
4170 // escape it by accident.
4171 set_cm_oop_closure(NULL);
4172 double end_time_ms = os::elapsedVTime() * 1000.0;
4173 double elapsed_time_ms = end_time_ms - _start_time_ms;
4174 // Update the step history.
4175 _step_times_ms.add(elapsed_time_ms);
4176
4177 if (has_aborted()) {
4178 // The task was aborted for some reason.
4179
4180 statsOnly( ++_aborted );
4181
4182 if (_has_timed_out) {
4183 double diff_ms = elapsed_time_ms - _time_target_ms;
4184 // Keep statistics of how well we did with respect to hitting
4185 // our target only if we actually timed out (if we aborted for
4186 // other reasons, then the results might get skewed).
4187 _marking_step_diffs_ms.add(diff_ms);
4188 }
4189
4190 if (_cm->has_overflown()) {
4191 // This is the interesting one. We aborted because a global
4192 // overflow was raised. This means we have to restart the
4193 // marking phase and start iterating over regions. However, in
4194 // order to do this we have to make sure that all tasks stop
4195 // what they are doing and re-initialise in a safe manner. We
4196 // will achieve this with the use of two barrier sync points.
4197
4198 if (_cm->verbose_low()) {
4199 gclog_or_tty->print_cr("[%d] detected overflow", _task_id);
4200 }
4201
4202 _cm->enter_first_sync_barrier(_task_id);
4203 // When we exit this sync barrier we know that all tasks have
4204 // stopped doing marking work. So, it's now safe to
4205 // re-initialise our data structures. At the end of this method,
4206 // task 0 will clear the global data structures.
4207
4208 statsOnly( ++_aborted_overflow );
4209
4210 // We clear the local state of this task...
4211 clear_region_fields();
4212
4213 // ...and enter the second barrier.
4214 _cm->enter_second_sync_barrier(_task_id);
4215 // At this point everything has bee re-initialised and we're
4216 // ready to restart.
4217 }
4218
4219 if (_cm->verbose_low()) {
4220 gclog_or_tty->print_cr("[%d] <<<<<<<<<< ABORTING, target = %1.2lfms, "
4221 "elapsed = %1.2lfms <<<<<<<<<<",
4222 _task_id, _time_target_ms, elapsed_time_ms);
4223 if (_cm->has_aborted()) {
4224 gclog_or_tty->print_cr("[%d] ========== MARKING ABORTED ==========",
4225 _task_id);
4226 }
4227 }
4228 } else {
4229 if (_cm->verbose_low()) {
4230 gclog_or_tty->print_cr("[%d] <<<<<<<<<< FINISHED, target = %1.2lfms, "
4231 "elapsed = %1.2lfms <<<<<<<<<<",
4232 _task_id, _time_target_ms, elapsed_time_ms);
4233 }
4234 }
4235
4236 _claimed = false;
4237 }
4238
4239 CMTask::CMTask(int task_id,
4240 ConcurrentMark* cm,
4241 size_t* marked_bytes,
4242 BitMap* card_bm,
4243 CMTaskQueue* task_queue,
4244 CMTaskQueueSet* task_queues)
4245 : _g1h(G1CollectedHeap::heap()),
4246 _task_id(task_id), _cm(cm),
4247 _claimed(false),
4248 _nextMarkBitMap(NULL), _hash_seed(17),
4249 _task_queue(task_queue),
4250 _task_queues(task_queues),
4251 _cm_oop_closure(NULL),
4252 _marked_bytes_array(marked_bytes),
4253 _card_bm(card_bm) {
4254 guarantee(task_queue != NULL, "invariant");
4255 guarantee(task_queues != NULL, "invariant");
4256
4257 statsOnly( _clock_due_to_scanning = 0;
4258 _clock_due_to_marking = 0 );
4259
4260 _marking_step_diffs_ms.add(0.5);
4261 }
4262
4263 // These are formatting macros that are used below to ensure
4264 // consistent formatting. The *_H_* versions are used to format the
4265 // header for a particular value and they should be kept consistent
4266 // with the corresponding macro. Also note that most of the macros add
4267 // the necessary white space (as a prefix) which makes them a bit
4268 // easier to compose.
4269
4270 // All the output lines are prefixed with this string to be able to
4271 // identify them easily in a large log file.
4272 #define G1PPRL_LINE_PREFIX "###"
4273
4274 #define G1PPRL_ADDR_BASE_FORMAT " "PTR_FORMAT"-"PTR_FORMAT
4275 #ifdef _LP64
4276 #define G1PPRL_ADDR_BASE_H_FORMAT " %37s"
4277 #else // _LP64
4278 #define G1PPRL_ADDR_BASE_H_FORMAT " %21s"
4279 #endif // _LP64
4280
4281 // For per-region info
4282 #define G1PPRL_TYPE_FORMAT " %-4s"
4283 #define G1PPRL_TYPE_H_FORMAT " %4s"
4284 #define G1PPRL_BYTE_FORMAT " "SIZE_FORMAT_W(9)
4285 #define G1PPRL_BYTE_H_FORMAT " %9s"
4286 #define G1PPRL_DOUBLE_FORMAT " %14.1f"
4287 #define G1PPRL_DOUBLE_H_FORMAT " %14s"
4288
4289 // For summary info
4290 #define G1PPRL_SUM_ADDR_FORMAT(tag) " "tag":"G1PPRL_ADDR_BASE_FORMAT
4291 #define G1PPRL_SUM_BYTE_FORMAT(tag) " "tag": "SIZE_FORMAT
4292 #define G1PPRL_SUM_MB_FORMAT(tag) " "tag": %1.2f MB"
4293 #define G1PPRL_SUM_MB_PERC_FORMAT(tag) G1PPRL_SUM_MB_FORMAT(tag)" / %1.2f %%"
4294
4295 G1PrintRegionLivenessInfoClosure::
4296 G1PrintRegionLivenessInfoClosure(outputStream* out, const char* phase_name)
4297 : _out(out),
4298 _total_used_bytes(0), _total_capacity_bytes(0),
4299 _total_prev_live_bytes(0), _total_next_live_bytes(0),
4300 _hum_used_bytes(0), _hum_capacity_bytes(0),
4301 _hum_prev_live_bytes(0), _hum_next_live_bytes(0) {
4302 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4303 MemRegion g1_committed = g1h->g1_committed();
4304 MemRegion g1_reserved = g1h->g1_reserved();
4305 double now = os::elapsedTime();
4306
4307 // Print the header of the output.
4308 _out->cr();
4309 _out->print_cr(G1PPRL_LINE_PREFIX" PHASE %s @ %1.3f", phase_name, now);
4310 _out->print_cr(G1PPRL_LINE_PREFIX" HEAP"
4311 G1PPRL_SUM_ADDR_FORMAT("committed")
4312 G1PPRL_SUM_ADDR_FORMAT("reserved")
4313 G1PPRL_SUM_BYTE_FORMAT("region-size"),
4314 g1_committed.start(), g1_committed.end(),
4315 g1_reserved.start(), g1_reserved.end(),
4316 HeapRegion::GrainBytes);
4317 _out->print_cr(G1PPRL_LINE_PREFIX);
4318 _out->print_cr(G1PPRL_LINE_PREFIX
4319 G1PPRL_TYPE_H_FORMAT
4320 G1PPRL_ADDR_BASE_H_FORMAT
4321 G1PPRL_BYTE_H_FORMAT
4322 G1PPRL_BYTE_H_FORMAT
4323 G1PPRL_BYTE_H_FORMAT
4324 G1PPRL_DOUBLE_H_FORMAT,
4325 "type", "address-range",
4326 "used", "prev-live", "next-live", "gc-eff");
4327 _out->print_cr(G1PPRL_LINE_PREFIX
4328 G1PPRL_TYPE_H_FORMAT
4329 G1PPRL_ADDR_BASE_H_FORMAT
4330 G1PPRL_BYTE_H_FORMAT
4331 G1PPRL_BYTE_H_FORMAT
4332 G1PPRL_BYTE_H_FORMAT
4333 G1PPRL_DOUBLE_H_FORMAT,
4334 "", "",
4335 "(bytes)", "(bytes)", "(bytes)", "(bytes/ms)");
4336 }
4337
4338 // It takes as a parameter a reference to one of the _hum_* fields, it
4339 // deduces the corresponding value for a region in a humongous region
4340 // series (either the region size, or what's left if the _hum_* field
4341 // is < the region size), and updates the _hum_* field accordingly.
4342 size_t G1PrintRegionLivenessInfoClosure::get_hum_bytes(size_t* hum_bytes) {
4343 size_t bytes = 0;
4344 // The > 0 check is to deal with the prev and next live bytes which
4345 // could be 0.
4346 if (*hum_bytes > 0) {
4347 bytes = MIN2(HeapRegion::GrainBytes, *hum_bytes);
4348 *hum_bytes -= bytes;
4349 }
4350 return bytes;
4351 }
4352
4353 // It deduces the values for a region in a humongous region series
4354 // from the _hum_* fields and updates those accordingly. It assumes
4355 // that that _hum_* fields have already been set up from the "starts
4356 // humongous" region and we visit the regions in address order.
4357 void G1PrintRegionLivenessInfoClosure::get_hum_bytes(size_t* used_bytes,
4358 size_t* capacity_bytes,
4359 size_t* prev_live_bytes,
4360 size_t* next_live_bytes) {
4361 assert(_hum_used_bytes > 0 && _hum_capacity_bytes > 0, "pre-condition");
4362 *used_bytes = get_hum_bytes(&_hum_used_bytes);
4363 *capacity_bytes = get_hum_bytes(&_hum_capacity_bytes);
4364 *prev_live_bytes = get_hum_bytes(&_hum_prev_live_bytes);
4365 *next_live_bytes = get_hum_bytes(&_hum_next_live_bytes);
4366 }
4367
4368 bool G1PrintRegionLivenessInfoClosure::doHeapRegion(HeapRegion* r) {
4369 const char* type = "";
4370 HeapWord* bottom = r->bottom();
4371 HeapWord* end = r->end();
4372 size_t capacity_bytes = r->capacity();
4373 size_t used_bytes = r->used();
4374 size_t prev_live_bytes = r->live_bytes();
4375 size_t next_live_bytes = r->next_live_bytes();
4376 double gc_eff = r->gc_efficiency();
4377 if (r->used() == 0) {
4378 type = "FREE";
4379 } else if (r->is_survivor()) {
4380 type = "SURV";
4381 } else if (r->is_young()) {
4382 type = "EDEN";
4383 } else if (r->startsHumongous()) {
4384 type = "HUMS";
4385
4386 assert(_hum_used_bytes == 0 && _hum_capacity_bytes == 0 &&
4387 _hum_prev_live_bytes == 0 && _hum_next_live_bytes == 0,
4388 "they should have been zeroed after the last time we used them");
4389 // Set up the _hum_* fields.
4390 _hum_capacity_bytes = capacity_bytes;
4391 _hum_used_bytes = used_bytes;
4392 _hum_prev_live_bytes = prev_live_bytes;
4393 _hum_next_live_bytes = next_live_bytes;
4394 get_hum_bytes(&used_bytes, &capacity_bytes,
4395 &prev_live_bytes, &next_live_bytes);
4396 end = bottom + HeapRegion::GrainWords;
4397 } else if (r->continuesHumongous()) {
4398 type = "HUMC";
4399 get_hum_bytes(&used_bytes, &capacity_bytes,
4400 &prev_live_bytes, &next_live_bytes);
4401 assert(end == bottom + HeapRegion::GrainWords, "invariant");
4402 } else {
4403 type = "OLD";
4404 }
4405
4406 _total_used_bytes += used_bytes;
4407 _total_capacity_bytes += capacity_bytes;
4408 _total_prev_live_bytes += prev_live_bytes;
4409 _total_next_live_bytes += next_live_bytes;
4410
4411 // Print a line for this particular region.
4412 _out->print_cr(G1PPRL_LINE_PREFIX
4413 G1PPRL_TYPE_FORMAT
4414 G1PPRL_ADDR_BASE_FORMAT
4415 G1PPRL_BYTE_FORMAT
4416 G1PPRL_BYTE_FORMAT
4417 G1PPRL_BYTE_FORMAT
4418 G1PPRL_DOUBLE_FORMAT,
4419 type, bottom, end,
4420 used_bytes, prev_live_bytes, next_live_bytes, gc_eff);
4421
4422 return false;
4423 }
4424
4425 G1PrintRegionLivenessInfoClosure::~G1PrintRegionLivenessInfoClosure() {
4426 // Print the footer of the output.
4427 _out->print_cr(G1PPRL_LINE_PREFIX);
4428 _out->print_cr(G1PPRL_LINE_PREFIX
4429 " SUMMARY"
4430 G1PPRL_SUM_MB_FORMAT("capacity")
4431 G1PPRL_SUM_MB_PERC_FORMAT("used")
4432 G1PPRL_SUM_MB_PERC_FORMAT("prev-live")
4433 G1PPRL_SUM_MB_PERC_FORMAT("next-live"),
4434 bytes_to_mb(_total_capacity_bytes),
4435 bytes_to_mb(_total_used_bytes),
4436 perc(_total_used_bytes, _total_capacity_bytes),
4437 bytes_to_mb(_total_prev_live_bytes),
4438 perc(_total_prev_live_bytes, _total_capacity_bytes),
4439 bytes_to_mb(_total_next_live_bytes),
4440 perc(_total_next_live_bytes, _total_capacity_bytes));
4441 _out->cr();
4442 }