Mon, 02 Jul 2012 13:11:28 -0400
Merge
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 */
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"
47 // Concurrent marking bit map wrapper
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));
57 MemTracker::record_virtual_memory_type((address)brs.base(), mtGC);
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 }
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 }
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 }
105 int CMBitMapRO::heapWordDiffToOffsetDiff(size_t diff) const {
106 assert((diff & ((1 << _shifter) - 1)) == 0, "argument check");
107 return (int) (diff >> _shifter);
108 }
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
120 void CMBitMap::clearAll() {
121 _bm.clear();
122 return;
123 }
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 }
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 }
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 }
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 {}
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 }
177 CMMarkStack::~CMMarkStack() {
178 if (_base != NULL) {
179 FREE_C_HEAP_ARRAY(oop, _base, mtGC);
180 }
181 }
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 }
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 }
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 }
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 }
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 }
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 }
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 }
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 }
317 bool ConcurrentMark::not_yet_marked(oop obj) const {
318 return (_g1h->is_obj_ill(obj)
319 || (_g1h->is_in_permanent(obj)
320 && !nextMarkBitMap()->isMarked((HeapWord*)obj)));
321 }
323 CMRootRegions::CMRootRegions() :
324 _young_list(NULL), _cm(NULL), _scan_in_progress(false),
325 _should_abort(false), _next_survivor(NULL) { }
327 void CMRootRegions::init(G1CollectedHeap* g1h, ConcurrentMark* cm) {
328 _young_list = g1h->young_list();
329 _cm = cm;
330 }
332 void CMRootRegions::prepare_for_scan() {
333 assert(!scan_in_progress(), "pre-condition");
335 // Currently, only survivors can be root regions.
336 assert(_next_survivor == NULL, "pre-condition");
337 _next_survivor = _young_list->first_survivor_region();
338 _scan_in_progress = (_next_survivor != NULL);
339 _should_abort = false;
340 }
342 HeapRegion* CMRootRegions::claim_next() {
343 if (_should_abort) {
344 // If someone has set the should_abort flag, we return NULL to
345 // force the caller to bail out of their loop.
346 return NULL;
347 }
349 // Currently, only survivors can be root regions.
350 HeapRegion* res = _next_survivor;
351 if (res != NULL) {
352 MutexLockerEx x(RootRegionScan_lock, Mutex::_no_safepoint_check_flag);
353 // Read it again in case it changed while we were waiting for the lock.
354 res = _next_survivor;
355 if (res != NULL) {
356 if (res == _young_list->last_survivor_region()) {
357 // We just claimed the last survivor so store NULL to indicate
358 // that we're done.
359 _next_survivor = NULL;
360 } else {
361 _next_survivor = res->get_next_young_region();
362 }
363 } else {
364 // Someone else claimed the last survivor while we were trying
365 // to take the lock so nothing else to do.
366 }
367 }
368 assert(res == NULL || res->is_survivor(), "post-condition");
370 return res;
371 }
373 void CMRootRegions::scan_finished() {
374 assert(scan_in_progress(), "pre-condition");
376 // Currently, only survivors can be root regions.
377 if (!_should_abort) {
378 assert(_next_survivor == NULL, "we should have claimed all survivors");
379 }
380 _next_survivor = NULL;
382 {
383 MutexLockerEx x(RootRegionScan_lock, Mutex::_no_safepoint_check_flag);
384 _scan_in_progress = false;
385 RootRegionScan_lock->notify_all();
386 }
387 }
389 bool CMRootRegions::wait_until_scan_finished() {
390 if (!scan_in_progress()) return false;
392 {
393 MutexLockerEx x(RootRegionScan_lock, Mutex::_no_safepoint_check_flag);
394 while (scan_in_progress()) {
395 RootRegionScan_lock->wait(Mutex::_no_safepoint_check_flag);
396 }
397 }
398 return true;
399 }
401 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
402 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
403 #endif // _MSC_VER
405 uint ConcurrentMark::scale_parallel_threads(uint n_par_threads) {
406 return MAX2((n_par_threads + 2) / 4, 1U);
407 }
409 ConcurrentMark::ConcurrentMark(ReservedSpace rs, uint max_regions) :
410 _markBitMap1(rs, MinObjAlignment - 1),
411 _markBitMap2(rs, MinObjAlignment - 1),
413 _parallel_marking_threads(0),
414 _max_parallel_marking_threads(0),
415 _sleep_factor(0.0),
416 _marking_task_overhead(1.0),
417 _cleanup_sleep_factor(0.0),
418 _cleanup_task_overhead(1.0),
419 _cleanup_list("Cleanup List"),
420 _region_bm((BitMap::idx_t) max_regions, false /* in_resource_area*/),
421 _card_bm((rs.size() + CardTableModRefBS::card_size - 1) >>
422 CardTableModRefBS::card_shift,
423 false /* in_resource_area*/),
425 _prevMarkBitMap(&_markBitMap1),
426 _nextMarkBitMap(&_markBitMap2),
428 _markStack(this),
429 // _finger set in set_non_marking_state
431 _max_task_num(MAX2((uint)ParallelGCThreads, 1U)),
432 // _active_tasks set in set_non_marking_state
433 // _tasks set inside the constructor
434 _task_queues(new CMTaskQueueSet((int) _max_task_num)),
435 _terminator(ParallelTaskTerminator((int) _max_task_num, _task_queues)),
437 _has_overflown(false),
438 _concurrent(false),
439 _has_aborted(false),
440 _restart_for_overflow(false),
441 _concurrent_marking_in_progress(false),
443 // _verbose_level set below
445 _init_times(),
446 _remark_times(), _remark_mark_times(), _remark_weak_ref_times(),
447 _cleanup_times(),
448 _total_counting_time(0.0),
449 _total_rs_scrub_time(0.0),
451 _parallel_workers(NULL),
453 _count_card_bitmaps(NULL),
454 _count_marked_bytes(NULL) {
455 CMVerboseLevel verbose_level = (CMVerboseLevel) G1MarkingVerboseLevel;
456 if (verbose_level < no_verbose) {
457 verbose_level = no_verbose;
458 }
459 if (verbose_level > high_verbose) {
460 verbose_level = high_verbose;
461 }
462 _verbose_level = verbose_level;
464 if (verbose_low()) {
465 gclog_or_tty->print_cr("[global] init, heap start = "PTR_FORMAT", "
466 "heap end = "PTR_FORMAT, _heap_start, _heap_end);
467 }
469 _markStack.allocate(MarkStackSize);
471 // Create & start a ConcurrentMark thread.
472 _cmThread = new ConcurrentMarkThread(this);
473 assert(cmThread() != NULL, "CM Thread should have been created");
474 assert(cmThread()->cm() != NULL, "CM Thread should refer to this cm");
476 _g1h = G1CollectedHeap::heap();
477 assert(CGC_lock != NULL, "Where's the CGC_lock?");
478 assert(_markBitMap1.covers(rs), "_markBitMap1 inconsistency");
479 assert(_markBitMap2.covers(rs), "_markBitMap2 inconsistency");
481 SATBMarkQueueSet& satb_qs = JavaThread::satb_mark_queue_set();
482 satb_qs.set_buffer_size(G1SATBBufferSize);
484 _root_regions.init(_g1h, this);
486 _tasks = NEW_C_HEAP_ARRAY(CMTask*, _max_task_num, mtGC);
487 _accum_task_vtime = NEW_C_HEAP_ARRAY(double, _max_task_num, mtGC);
489 _count_card_bitmaps = NEW_C_HEAP_ARRAY(BitMap, _max_task_num, mtGC);
490 _count_marked_bytes = NEW_C_HEAP_ARRAY(size_t*, _max_task_num, mtGC);
492 BitMap::idx_t card_bm_size = _card_bm.size();
494 // so that the assertion in MarkingTaskQueue::task_queue doesn't fail
495 _active_tasks = _max_task_num;
496 for (int i = 0; i < (int) _max_task_num; ++i) {
497 CMTaskQueue* task_queue = new CMTaskQueue();
498 task_queue->initialize();
499 _task_queues->register_queue(i, task_queue);
501 _count_card_bitmaps[i] = BitMap(card_bm_size, false);
502 _count_marked_bytes[i] = NEW_C_HEAP_ARRAY(size_t, (size_t) max_regions, mtGC);
504 _tasks[i] = new CMTask(i, this,
505 _count_marked_bytes[i],
506 &_count_card_bitmaps[i],
507 task_queue, _task_queues);
509 _accum_task_vtime[i] = 0.0;
510 }
512 // Calculate the card number for the bottom of the heap. Used
513 // in biasing indexes into the accounting card bitmaps.
514 _heap_bottom_card_num =
515 intptr_t(uintptr_t(_g1h->reserved_region().start()) >>
516 CardTableModRefBS::card_shift);
518 // Clear all the liveness counting data
519 clear_all_count_data();
521 if (ConcGCThreads > ParallelGCThreads) {
522 vm_exit_during_initialization("Can't have more ConcGCThreads "
523 "than ParallelGCThreads.");
524 }
525 if (ParallelGCThreads == 0) {
526 // if we are not running with any parallel GC threads we will not
527 // spawn any marking threads either
528 _parallel_marking_threads = 0;
529 _max_parallel_marking_threads = 0;
530 _sleep_factor = 0.0;
531 _marking_task_overhead = 1.0;
532 } else {
533 if (ConcGCThreads > 0) {
534 // notice that ConcGCThreads overwrites G1MarkingOverheadPercent
535 // if both are set
537 _parallel_marking_threads = (uint) ConcGCThreads;
538 _max_parallel_marking_threads = _parallel_marking_threads;
539 _sleep_factor = 0.0;
540 _marking_task_overhead = 1.0;
541 } else if (G1MarkingOverheadPercent > 0) {
542 // we will calculate the number of parallel marking threads
543 // based on a target overhead with respect to the soft real-time
544 // goal
546 double marking_overhead = (double) G1MarkingOverheadPercent / 100.0;
547 double overall_cm_overhead =
548 (double) MaxGCPauseMillis * marking_overhead /
549 (double) GCPauseIntervalMillis;
550 double cpu_ratio = 1.0 / (double) os::processor_count();
551 double marking_thread_num = ceil(overall_cm_overhead / cpu_ratio);
552 double marking_task_overhead =
553 overall_cm_overhead / marking_thread_num *
554 (double) os::processor_count();
555 double sleep_factor =
556 (1.0 - marking_task_overhead) / marking_task_overhead;
558 _parallel_marking_threads = (uint) marking_thread_num;
559 _max_parallel_marking_threads = _parallel_marking_threads;
560 _sleep_factor = sleep_factor;
561 _marking_task_overhead = marking_task_overhead;
562 } else {
563 _parallel_marking_threads = scale_parallel_threads((uint)ParallelGCThreads);
564 _max_parallel_marking_threads = _parallel_marking_threads;
565 _sleep_factor = 0.0;
566 _marking_task_overhead = 1.0;
567 }
569 if (parallel_marking_threads() > 1) {
570 _cleanup_task_overhead = 1.0;
571 } else {
572 _cleanup_task_overhead = marking_task_overhead();
573 }
574 _cleanup_sleep_factor =
575 (1.0 - cleanup_task_overhead()) / cleanup_task_overhead();
577 #if 0
578 gclog_or_tty->print_cr("Marking Threads %d", parallel_marking_threads());
579 gclog_or_tty->print_cr("CM Marking Task Overhead %1.4lf", marking_task_overhead());
580 gclog_or_tty->print_cr("CM Sleep Factor %1.4lf", sleep_factor());
581 gclog_or_tty->print_cr("CL Marking Task Overhead %1.4lf", cleanup_task_overhead());
582 gclog_or_tty->print_cr("CL Sleep Factor %1.4lf", cleanup_sleep_factor());
583 #endif
585 guarantee(parallel_marking_threads() > 0, "peace of mind");
586 _parallel_workers = new FlexibleWorkGang("G1 Parallel Marking Threads",
587 _max_parallel_marking_threads, false, true);
588 if (_parallel_workers == NULL) {
589 vm_exit_during_initialization("Failed necessary allocation.");
590 } else {
591 _parallel_workers->initialize_workers();
592 }
593 }
595 // so that the call below can read a sensible value
596 _heap_start = (HeapWord*) rs.base();
597 set_non_marking_state();
598 }
600 void ConcurrentMark::update_g1_committed(bool force) {
601 // If concurrent marking is not in progress, then we do not need to
602 // update _heap_end.
603 if (!concurrent_marking_in_progress() && !force) return;
605 MemRegion committed = _g1h->g1_committed();
606 assert(committed.start() == _heap_start, "start shouldn't change");
607 HeapWord* new_end = committed.end();
608 if (new_end > _heap_end) {
609 // The heap has been expanded.
611 _heap_end = new_end;
612 }
613 // Notice that the heap can also shrink. However, this only happens
614 // during a Full GC (at least currently) and the entire marking
615 // phase will bail out and the task will not be restarted. So, let's
616 // do nothing.
617 }
619 void ConcurrentMark::reset() {
620 // Starting values for these two. This should be called in a STW
621 // phase. CM will be notified of any future g1_committed expansions
622 // will be at the end of evacuation pauses, when tasks are
623 // inactive.
624 MemRegion committed = _g1h->g1_committed();
625 _heap_start = committed.start();
626 _heap_end = committed.end();
628 // Separated the asserts so that we know which one fires.
629 assert(_heap_start != NULL, "heap bounds should look ok");
630 assert(_heap_end != NULL, "heap bounds should look ok");
631 assert(_heap_start < _heap_end, "heap bounds should look ok");
633 // reset all the marking data structures and any necessary flags
634 clear_marking_state();
636 if (verbose_low()) {
637 gclog_or_tty->print_cr("[global] resetting");
638 }
640 // We do reset all of them, since different phases will use
641 // different number of active threads. So, it's easiest to have all
642 // of them ready.
643 for (int i = 0; i < (int) _max_task_num; ++i) {
644 _tasks[i]->reset(_nextMarkBitMap);
645 }
647 // we need this to make sure that the flag is on during the evac
648 // pause with initial mark piggy-backed
649 set_concurrent_marking_in_progress();
650 }
652 void ConcurrentMark::set_phase(uint active_tasks, bool concurrent) {
653 assert(active_tasks <= _max_task_num, "we should not have more");
655 _active_tasks = active_tasks;
656 // Need to update the three data structures below according to the
657 // number of active threads for this phase.
658 _terminator = ParallelTaskTerminator((int) active_tasks, _task_queues);
659 _first_overflow_barrier_sync.set_n_workers((int) active_tasks);
660 _second_overflow_barrier_sync.set_n_workers((int) active_tasks);
662 _concurrent = concurrent;
663 // We propagate this to all tasks, not just the active ones.
664 for (int i = 0; i < (int) _max_task_num; ++i)
665 _tasks[i]->set_concurrent(concurrent);
667 if (concurrent) {
668 set_concurrent_marking_in_progress();
669 } else {
670 // We currently assume that the concurrent flag has been set to
671 // false before we start remark. At this point we should also be
672 // in a STW phase.
673 assert(!concurrent_marking_in_progress(), "invariant");
674 assert(_finger == _heap_end, "only way to get here");
675 update_g1_committed(true);
676 }
677 }
679 void ConcurrentMark::set_non_marking_state() {
680 // We set the global marking state to some default values when we're
681 // not doing marking.
682 clear_marking_state();
683 _active_tasks = 0;
684 clear_concurrent_marking_in_progress();
685 }
687 ConcurrentMark::~ConcurrentMark() {
688 // The ConcurrentMark instance is never freed.
689 ShouldNotReachHere();
690 }
692 void ConcurrentMark::clearNextBitmap() {
693 G1CollectedHeap* g1h = G1CollectedHeap::heap();
694 G1CollectorPolicy* g1p = g1h->g1_policy();
696 // Make sure that the concurrent mark thread looks to still be in
697 // the current cycle.
698 guarantee(cmThread()->during_cycle(), "invariant");
700 // We are finishing up the current cycle by clearing the next
701 // marking bitmap and getting it ready for the next cycle. During
702 // this time no other cycle can start. So, let's make sure that this
703 // is the case.
704 guarantee(!g1h->mark_in_progress(), "invariant");
706 // clear the mark bitmap (no grey objects to start with).
707 // We need to do this in chunks and offer to yield in between
708 // each chunk.
709 HeapWord* start = _nextMarkBitMap->startWord();
710 HeapWord* end = _nextMarkBitMap->endWord();
711 HeapWord* cur = start;
712 size_t chunkSize = M;
713 while (cur < end) {
714 HeapWord* next = cur + chunkSize;
715 if (next > end) {
716 next = end;
717 }
718 MemRegion mr(cur,next);
719 _nextMarkBitMap->clearRange(mr);
720 cur = next;
721 do_yield_check();
723 // Repeat the asserts from above. We'll do them as asserts here to
724 // minimize their overhead on the product. However, we'll have
725 // them as guarantees at the beginning / end of the bitmap
726 // clearing to get some checking in the product.
727 assert(cmThread()->during_cycle(), "invariant");
728 assert(!g1h->mark_in_progress(), "invariant");
729 }
731 // Clear the liveness counting data
732 clear_all_count_data();
734 // Repeat the asserts from above.
735 guarantee(cmThread()->during_cycle(), "invariant");
736 guarantee(!g1h->mark_in_progress(), "invariant");
737 }
739 class NoteStartOfMarkHRClosure: public HeapRegionClosure {
740 public:
741 bool doHeapRegion(HeapRegion* r) {
742 if (!r->continuesHumongous()) {
743 r->note_start_of_marking();
744 }
745 return false;
746 }
747 };
749 void ConcurrentMark::checkpointRootsInitialPre() {
750 G1CollectedHeap* g1h = G1CollectedHeap::heap();
751 G1CollectorPolicy* g1p = g1h->g1_policy();
753 _has_aborted = false;
755 #ifndef PRODUCT
756 if (G1PrintReachableAtInitialMark) {
757 print_reachable("at-cycle-start",
758 VerifyOption_G1UsePrevMarking, true /* all */);
759 }
760 #endif
762 // Initialise marking structures. This has to be done in a STW phase.
763 reset();
765 // For each region note start of marking.
766 NoteStartOfMarkHRClosure startcl;
767 g1h->heap_region_iterate(&startcl);
768 }
771 void ConcurrentMark::checkpointRootsInitialPost() {
772 G1CollectedHeap* g1h = G1CollectedHeap::heap();
774 // If we force an overflow during remark, the remark operation will
775 // actually abort and we'll restart concurrent marking. If we always
776 // force an oveflow during remark we'll never actually complete the
777 // marking phase. So, we initilize this here, at the start of the
778 // cycle, so that at the remaining overflow number will decrease at
779 // every remark and we'll eventually not need to cause one.
780 force_overflow_stw()->init();
782 // Start Concurrent Marking weak-reference discovery.
783 ReferenceProcessor* rp = g1h->ref_processor_cm();
784 // enable ("weak") refs discovery
785 rp->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
786 rp->setup_policy(false); // snapshot the soft ref policy to be used in this cycle
788 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
789 // This is the start of the marking cycle, we're expected all
790 // threads to have SATB queues with active set to false.
791 satb_mq_set.set_active_all_threads(true, /* new active value */
792 false /* expected_active */);
794 _root_regions.prepare_for_scan();
796 // update_g1_committed() will be called at the end of an evac pause
797 // when marking is on. So, it's also called at the end of the
798 // initial-mark pause to update the heap end, if the heap expands
799 // during it. No need to call it here.
800 }
802 /*
803 * Notice that in the next two methods, we actually leave the STS
804 * during the barrier sync and join it immediately afterwards. If we
805 * do not do this, the following deadlock can occur: one thread could
806 * be in the barrier sync code, waiting for the other thread to also
807 * sync up, whereas another one could be trying to yield, while also
808 * waiting for the other threads to sync up too.
809 *
810 * Note, however, that this code is also used during remark and in
811 * this case we should not attempt to leave / enter the STS, otherwise
812 * we'll either hit an asseert (debug / fastdebug) or deadlock
813 * (product). So we should only leave / enter the STS if we are
814 * operating concurrently.
815 *
816 * Because the thread that does the sync barrier has left the STS, it
817 * is possible to be suspended for a Full GC or an evacuation pause
818 * could occur. This is actually safe, since the entering the sync
819 * barrier is one of the last things do_marking_step() does, and it
820 * doesn't manipulate any data structures afterwards.
821 */
823 void ConcurrentMark::enter_first_sync_barrier(int task_num) {
824 if (verbose_low()) {
825 gclog_or_tty->print_cr("[%d] entering first barrier", task_num);
826 }
828 if (concurrent()) {
829 ConcurrentGCThread::stsLeave();
830 }
831 _first_overflow_barrier_sync.enter();
832 if (concurrent()) {
833 ConcurrentGCThread::stsJoin();
834 }
835 // at this point everyone should have synced up and not be doing any
836 // more work
838 if (verbose_low()) {
839 gclog_or_tty->print_cr("[%d] leaving first barrier", task_num);
840 }
842 // let task 0 do this
843 if (task_num == 0) {
844 // task 0 is responsible for clearing the global data structures
845 // We should be here because of an overflow. During STW we should
846 // not clear the overflow flag since we rely on it being true when
847 // we exit this method to abort the pause and restart concurent
848 // marking.
849 clear_marking_state(concurrent() /* clear_overflow */);
850 force_overflow()->update();
852 if (G1Log::fine()) {
853 gclog_or_tty->date_stamp(PrintGCDateStamps);
854 gclog_or_tty->stamp(PrintGCTimeStamps);
855 gclog_or_tty->print_cr("[GC concurrent-mark-reset-for-overflow]");
856 }
857 }
859 // after this, each task should reset its own data structures then
860 // then go into the second barrier
861 }
863 void ConcurrentMark::enter_second_sync_barrier(int task_num) {
864 if (verbose_low()) {
865 gclog_or_tty->print_cr("[%d] entering second barrier", task_num);
866 }
868 if (concurrent()) {
869 ConcurrentGCThread::stsLeave();
870 }
871 _second_overflow_barrier_sync.enter();
872 if (concurrent()) {
873 ConcurrentGCThread::stsJoin();
874 }
875 // at this point everything should be re-initialised and ready to go
877 if (verbose_low()) {
878 gclog_or_tty->print_cr("[%d] leaving second barrier", task_num);
879 }
880 }
882 #ifndef PRODUCT
883 void ForceOverflowSettings::init() {
884 _num_remaining = G1ConcMarkForceOverflow;
885 _force = false;
886 update();
887 }
889 void ForceOverflowSettings::update() {
890 if (_num_remaining > 0) {
891 _num_remaining -= 1;
892 _force = true;
893 } else {
894 _force = false;
895 }
896 }
898 bool ForceOverflowSettings::should_force() {
899 if (_force) {
900 _force = false;
901 return true;
902 } else {
903 return false;
904 }
905 }
906 #endif // !PRODUCT
908 class CMConcurrentMarkingTask: public AbstractGangTask {
909 private:
910 ConcurrentMark* _cm;
911 ConcurrentMarkThread* _cmt;
913 public:
914 void work(uint worker_id) {
915 assert(Thread::current()->is_ConcurrentGC_thread(),
916 "this should only be done by a conc GC thread");
917 ResourceMark rm;
919 double start_vtime = os::elapsedVTime();
921 ConcurrentGCThread::stsJoin();
923 assert(worker_id < _cm->active_tasks(), "invariant");
924 CMTask* the_task = _cm->task(worker_id);
925 the_task->record_start_time();
926 if (!_cm->has_aborted()) {
927 do {
928 double start_vtime_sec = os::elapsedVTime();
929 double start_time_sec = os::elapsedTime();
930 double mark_step_duration_ms = G1ConcMarkStepDurationMillis;
932 the_task->do_marking_step(mark_step_duration_ms,
933 true /* do_stealing */,
934 true /* do_termination */);
936 double end_time_sec = os::elapsedTime();
937 double end_vtime_sec = os::elapsedVTime();
938 double elapsed_vtime_sec = end_vtime_sec - start_vtime_sec;
939 double elapsed_time_sec = end_time_sec - start_time_sec;
940 _cm->clear_has_overflown();
942 bool ret = _cm->do_yield_check(worker_id);
944 jlong sleep_time_ms;
945 if (!_cm->has_aborted() && the_task->has_aborted()) {
946 sleep_time_ms =
947 (jlong) (elapsed_vtime_sec * _cm->sleep_factor() * 1000.0);
948 ConcurrentGCThread::stsLeave();
949 os::sleep(Thread::current(), sleep_time_ms, false);
950 ConcurrentGCThread::stsJoin();
951 }
952 double end_time2_sec = os::elapsedTime();
953 double elapsed_time2_sec = end_time2_sec - start_time_sec;
955 #if 0
956 gclog_or_tty->print_cr("CM: elapsed %1.4lf ms, sleep %1.4lf ms, "
957 "overhead %1.4lf",
958 elapsed_vtime_sec * 1000.0, (double) sleep_time_ms,
959 the_task->conc_overhead(os::elapsedTime()) * 8.0);
960 gclog_or_tty->print_cr("elapsed time %1.4lf ms, time 2: %1.4lf ms",
961 elapsed_time_sec * 1000.0, elapsed_time2_sec * 1000.0);
962 #endif
963 } while (!_cm->has_aborted() && the_task->has_aborted());
964 }
965 the_task->record_end_time();
966 guarantee(!the_task->has_aborted() || _cm->has_aborted(), "invariant");
968 ConcurrentGCThread::stsLeave();
970 double end_vtime = os::elapsedVTime();
971 _cm->update_accum_task_vtime(worker_id, end_vtime - start_vtime);
972 }
974 CMConcurrentMarkingTask(ConcurrentMark* cm,
975 ConcurrentMarkThread* cmt) :
976 AbstractGangTask("Concurrent Mark"), _cm(cm), _cmt(cmt) { }
978 ~CMConcurrentMarkingTask() { }
979 };
981 // Calculates the number of active workers for a concurrent
982 // phase.
983 uint ConcurrentMark::calc_parallel_marking_threads() {
984 if (G1CollectedHeap::use_parallel_gc_threads()) {
985 uint n_conc_workers = 0;
986 if (!UseDynamicNumberOfGCThreads ||
987 (!FLAG_IS_DEFAULT(ConcGCThreads) &&
988 !ForceDynamicNumberOfGCThreads)) {
989 n_conc_workers = max_parallel_marking_threads();
990 } else {
991 n_conc_workers =
992 AdaptiveSizePolicy::calc_default_active_workers(
993 max_parallel_marking_threads(),
994 1, /* Minimum workers */
995 parallel_marking_threads(),
996 Threads::number_of_non_daemon_threads());
997 // Don't scale down "n_conc_workers" by scale_parallel_threads() because
998 // that scaling has already gone into "_max_parallel_marking_threads".
999 }
1000 assert(n_conc_workers > 0, "Always need at least 1");
1001 return n_conc_workers;
1002 }
1003 // If we are not running with any parallel GC threads we will not
1004 // have spawned any marking threads either. Hence the number of
1005 // concurrent workers should be 0.
1006 return 0;
1007 }
1009 void ConcurrentMark::scanRootRegion(HeapRegion* hr, uint worker_id) {
1010 // Currently, only survivors can be root regions.
1011 assert(hr->next_top_at_mark_start() == hr->bottom(), "invariant");
1012 G1RootRegionScanClosure cl(_g1h, this, worker_id);
1014 const uintx interval = PrefetchScanIntervalInBytes;
1015 HeapWord* curr = hr->bottom();
1016 const HeapWord* end = hr->top();
1017 while (curr < end) {
1018 Prefetch::read(curr, interval);
1019 oop obj = oop(curr);
1020 int size = obj->oop_iterate(&cl);
1021 assert(size == obj->size(), "sanity");
1022 curr += size;
1023 }
1024 }
1026 class CMRootRegionScanTask : public AbstractGangTask {
1027 private:
1028 ConcurrentMark* _cm;
1030 public:
1031 CMRootRegionScanTask(ConcurrentMark* cm) :
1032 AbstractGangTask("Root Region Scan"), _cm(cm) { }
1034 void work(uint worker_id) {
1035 assert(Thread::current()->is_ConcurrentGC_thread(),
1036 "this should only be done by a conc GC thread");
1038 CMRootRegions* root_regions = _cm->root_regions();
1039 HeapRegion* hr = root_regions->claim_next();
1040 while (hr != NULL) {
1041 _cm->scanRootRegion(hr, worker_id);
1042 hr = root_regions->claim_next();
1043 }
1044 }
1045 };
1047 void ConcurrentMark::scanRootRegions() {
1048 // scan_in_progress() will have been set to true only if there was
1049 // at least one root region to scan. So, if it's false, we
1050 // should not attempt to do any further work.
1051 if (root_regions()->scan_in_progress()) {
1052 _parallel_marking_threads = calc_parallel_marking_threads();
1053 assert(parallel_marking_threads() <= max_parallel_marking_threads(),
1054 "Maximum number of marking threads exceeded");
1055 uint active_workers = MAX2(1U, parallel_marking_threads());
1057 CMRootRegionScanTask task(this);
1058 if (parallel_marking_threads() > 0) {
1059 _parallel_workers->set_active_workers((int) active_workers);
1060 _parallel_workers->run_task(&task);
1061 } else {
1062 task.work(0);
1063 }
1065 // It's possible that has_aborted() is true here without actually
1066 // aborting the survivor scan earlier. This is OK as it's
1067 // mainly used for sanity checking.
1068 root_regions()->scan_finished();
1069 }
1070 }
1072 void ConcurrentMark::markFromRoots() {
1073 // we might be tempted to assert that:
1074 // assert(asynch == !SafepointSynchronize::is_at_safepoint(),
1075 // "inconsistent argument?");
1076 // However that wouldn't be right, because it's possible that
1077 // a safepoint is indeed in progress as a younger generation
1078 // stop-the-world GC happens even as we mark in this generation.
1080 _restart_for_overflow = false;
1081 force_overflow_conc()->init();
1083 // _g1h has _n_par_threads
1084 _parallel_marking_threads = calc_parallel_marking_threads();
1085 assert(parallel_marking_threads() <= max_parallel_marking_threads(),
1086 "Maximum number of marking threads exceeded");
1088 uint active_workers = MAX2(1U, parallel_marking_threads());
1090 // Parallel task terminator is set in "set_phase()"
1091 set_phase(active_workers, true /* concurrent */);
1093 CMConcurrentMarkingTask markingTask(this, cmThread());
1094 if (parallel_marking_threads() > 0) {
1095 _parallel_workers->set_active_workers((int)active_workers);
1096 // Don't set _n_par_threads because it affects MT in proceess_strong_roots()
1097 // and the decisions on that MT processing is made elsewhere.
1098 assert(_parallel_workers->active_workers() > 0, "Should have been set");
1099 _parallel_workers->run_task(&markingTask);
1100 } else {
1101 markingTask.work(0);
1102 }
1103 print_stats();
1104 }
1106 void ConcurrentMark::checkpointRootsFinal(bool clear_all_soft_refs) {
1107 // world is stopped at this checkpoint
1108 assert(SafepointSynchronize::is_at_safepoint(),
1109 "world should be stopped");
1111 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1113 // If a full collection has happened, we shouldn't do this.
1114 if (has_aborted()) {
1115 g1h->set_marking_complete(); // So bitmap clearing isn't confused
1116 return;
1117 }
1119 SvcGCMarker sgcm(SvcGCMarker::OTHER);
1121 if (VerifyDuringGC) {
1122 HandleMark hm; // handle scope
1123 gclog_or_tty->print(" VerifyDuringGC:(before)");
1124 Universe::heap()->prepare_for_verify();
1125 Universe::verify(/* silent */ false,
1126 /* option */ VerifyOption_G1UsePrevMarking);
1127 }
1129 G1CollectorPolicy* g1p = g1h->g1_policy();
1130 g1p->record_concurrent_mark_remark_start();
1132 double start = os::elapsedTime();
1134 checkpointRootsFinalWork();
1136 double mark_work_end = os::elapsedTime();
1138 weakRefsWork(clear_all_soft_refs);
1140 if (has_overflown()) {
1141 // Oops. We overflowed. Restart concurrent marking.
1142 _restart_for_overflow = true;
1143 // Clear the flag. We do not need it any more.
1144 clear_has_overflown();
1145 if (G1TraceMarkStackOverflow) {
1146 gclog_or_tty->print_cr("\nRemark led to restart for overflow.");
1147 }
1148 } else {
1149 // Aggregate the per-task counting data that we have accumulated
1150 // while marking.
1151 aggregate_count_data();
1153 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
1154 // We're done with marking.
1155 // This is the end of the marking cycle, we're expected all
1156 // threads to have SATB queues with active set to true.
1157 satb_mq_set.set_active_all_threads(false, /* new active value */
1158 true /* expected_active */);
1160 if (VerifyDuringGC) {
1161 HandleMark hm; // handle scope
1162 gclog_or_tty->print(" VerifyDuringGC:(after)");
1163 Universe::heap()->prepare_for_verify();
1164 Universe::verify(/* silent */ false,
1165 /* option */ VerifyOption_G1UseNextMarking);
1166 }
1167 assert(!restart_for_overflow(), "sanity");
1168 }
1170 // Reset the marking state if marking completed
1171 if (!restart_for_overflow()) {
1172 set_non_marking_state();
1173 }
1175 #if VERIFY_OBJS_PROCESSED
1176 _scan_obj_cl.objs_processed = 0;
1177 ThreadLocalObjQueue::objs_enqueued = 0;
1178 #endif
1180 // Statistics
1181 double now = os::elapsedTime();
1182 _remark_mark_times.add((mark_work_end - start) * 1000.0);
1183 _remark_weak_ref_times.add((now - mark_work_end) * 1000.0);
1184 _remark_times.add((now - start) * 1000.0);
1186 g1p->record_concurrent_mark_remark_end();
1187 }
1189 // Base class of the closures that finalize and verify the
1190 // liveness counting data.
1191 class CMCountDataClosureBase: public HeapRegionClosure {
1192 protected:
1193 ConcurrentMark* _cm;
1194 BitMap* _region_bm;
1195 BitMap* _card_bm;
1197 void set_card_bitmap_range(BitMap::idx_t start_idx, BitMap::idx_t last_idx) {
1198 assert(start_idx <= last_idx, "sanity");
1200 // Set the inclusive bit range [start_idx, last_idx].
1201 // For small ranges (up to 8 cards) use a simple loop; otherwise
1202 // use par_at_put_range.
1203 if ((last_idx - start_idx) < 8) {
1204 for (BitMap::idx_t i = start_idx; i <= last_idx; i += 1) {
1205 _card_bm->par_set_bit(i);
1206 }
1207 } else {
1208 assert(last_idx < _card_bm->size(), "sanity");
1209 // Note BitMap::par_at_put_range() is exclusive.
1210 _card_bm->par_at_put_range(start_idx, last_idx+1, true);
1211 }
1212 }
1214 // It takes a region that's not empty (i.e., it has at least one
1215 // live object in it and sets its corresponding bit on the region
1216 // bitmap to 1. If the region is "starts humongous" it will also set
1217 // to 1 the bits on the region bitmap that correspond to its
1218 // associated "continues humongous" regions.
1219 void set_bit_for_region(HeapRegion* hr) {
1220 assert(!hr->continuesHumongous(), "should have filtered those out");
1222 BitMap::idx_t index = (BitMap::idx_t) hr->hrs_index();
1223 if (!hr->startsHumongous()) {
1224 // Normal (non-humongous) case: just set the bit.
1225 _region_bm->par_at_put(index, true);
1226 } else {
1227 // Starts humongous case: calculate how many regions are part of
1228 // this humongous region and then set the bit range.
1229 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1230 HeapRegion *last_hr = g1h->heap_region_containing_raw(hr->end() - 1);
1231 BitMap::idx_t end_index = (BitMap::idx_t) last_hr->hrs_index() + 1;
1232 _region_bm->par_at_put_range(index, end_index, true);
1233 }
1234 }
1236 public:
1237 CMCountDataClosureBase(ConcurrentMark *cm,
1238 BitMap* region_bm, BitMap* card_bm):
1239 _cm(cm), _region_bm(region_bm), _card_bm(card_bm) { }
1240 };
1242 // Closure that calculates the # live objects per region. Used
1243 // for verification purposes during the cleanup pause.
1244 class CalcLiveObjectsClosure: public CMCountDataClosureBase {
1245 CMBitMapRO* _bm;
1246 size_t _region_marked_bytes;
1248 public:
1249 CalcLiveObjectsClosure(CMBitMapRO *bm, ConcurrentMark *cm,
1250 BitMap* region_bm, BitMap* card_bm) :
1251 CMCountDataClosureBase(cm, region_bm, card_bm),
1252 _bm(bm), _region_marked_bytes(0) { }
1254 bool doHeapRegion(HeapRegion* hr) {
1256 if (hr->continuesHumongous()) {
1257 // We will ignore these here and process them when their
1258 // associated "starts humongous" region is processed (see
1259 // set_bit_for_heap_region()). Note that we cannot rely on their
1260 // associated "starts humongous" region to have their bit set to
1261 // 1 since, due to the region chunking in the parallel region
1262 // iteration, a "continues humongous" region might be visited
1263 // before its associated "starts humongous".
1264 return false;
1265 }
1267 HeapWord* nextTop = hr->next_top_at_mark_start();
1268 HeapWord* start = hr->bottom();
1270 assert(start <= hr->end() && start <= nextTop && nextTop <= hr->end(),
1271 err_msg("Preconditions not met - "
1272 "start: "PTR_FORMAT", nextTop: "PTR_FORMAT", end: "PTR_FORMAT,
1273 start, nextTop, hr->end()));
1275 // Find the first marked object at or after "start".
1276 start = _bm->getNextMarkedWordAddress(start, nextTop);
1278 size_t marked_bytes = 0;
1280 while (start < nextTop) {
1281 oop obj = oop(start);
1282 int obj_sz = obj->size();
1283 HeapWord* obj_last = start + obj_sz - 1;
1285 BitMap::idx_t start_idx = _cm->card_bitmap_index_for(start);
1286 BitMap::idx_t last_idx = _cm->card_bitmap_index_for(obj_last);
1288 // Set the bits in the card BM for this object (inclusive).
1289 set_card_bitmap_range(start_idx, last_idx);
1291 // Add the size of this object to the number of marked bytes.
1292 marked_bytes += (size_t)obj_sz * HeapWordSize;
1294 // Find the next marked object after this one.
1295 start = _bm->getNextMarkedWordAddress(obj_last + 1, nextTop);
1296 }
1298 // Mark the allocated-since-marking portion...
1299 HeapWord* top = hr->top();
1300 if (nextTop < top) {
1301 BitMap::idx_t start_idx = _cm->card_bitmap_index_for(nextTop);
1302 BitMap::idx_t last_idx = _cm->card_bitmap_index_for(top - 1);
1304 set_card_bitmap_range(start_idx, last_idx);
1306 // This definitely means the region has live objects.
1307 set_bit_for_region(hr);
1308 }
1310 // Update the live region bitmap.
1311 if (marked_bytes > 0) {
1312 set_bit_for_region(hr);
1313 }
1315 // Set the marked bytes for the current region so that
1316 // it can be queried by a calling verificiation routine
1317 _region_marked_bytes = marked_bytes;
1319 return false;
1320 }
1322 size_t region_marked_bytes() const { return _region_marked_bytes; }
1323 };
1325 // Heap region closure used for verifying the counting data
1326 // that was accumulated concurrently and aggregated during
1327 // the remark pause. This closure is applied to the heap
1328 // regions during the STW cleanup pause.
1330 class VerifyLiveObjectDataHRClosure: public HeapRegionClosure {
1331 ConcurrentMark* _cm;
1332 CalcLiveObjectsClosure _calc_cl;
1333 BitMap* _region_bm; // Region BM to be verified
1334 BitMap* _card_bm; // Card BM to be verified
1335 bool _verbose; // verbose output?
1337 BitMap* _exp_region_bm; // Expected Region BM values
1338 BitMap* _exp_card_bm; // Expected card BM values
1340 int _failures;
1342 public:
1343 VerifyLiveObjectDataHRClosure(ConcurrentMark* cm,
1344 BitMap* region_bm,
1345 BitMap* card_bm,
1346 BitMap* exp_region_bm,
1347 BitMap* exp_card_bm,
1348 bool verbose) :
1349 _cm(cm),
1350 _calc_cl(_cm->nextMarkBitMap(), _cm, exp_region_bm, exp_card_bm),
1351 _region_bm(region_bm), _card_bm(card_bm), _verbose(verbose),
1352 _exp_region_bm(exp_region_bm), _exp_card_bm(exp_card_bm),
1353 _failures(0) { }
1355 int failures() const { return _failures; }
1357 bool doHeapRegion(HeapRegion* hr) {
1358 if (hr->continuesHumongous()) {
1359 // We will ignore these here and process them when their
1360 // associated "starts humongous" region is processed (see
1361 // set_bit_for_heap_region()). Note that we cannot rely on their
1362 // associated "starts humongous" region to have their bit set to
1363 // 1 since, due to the region chunking in the parallel region
1364 // iteration, a "continues humongous" region might be visited
1365 // before its associated "starts humongous".
1366 return false;
1367 }
1369 int failures = 0;
1371 // Call the CalcLiveObjectsClosure to walk the marking bitmap for
1372 // this region and set the corresponding bits in the expected region
1373 // and card bitmaps.
1374 bool res = _calc_cl.doHeapRegion(hr);
1375 assert(res == false, "should be continuing");
1377 MutexLockerEx x((_verbose ? ParGCRareEvent_lock : NULL),
1378 Mutex::_no_safepoint_check_flag);
1380 // Verify the marked bytes for this region.
1381 size_t exp_marked_bytes = _calc_cl.region_marked_bytes();
1382 size_t act_marked_bytes = hr->next_marked_bytes();
1384 // We're not OK if expected marked bytes > actual marked bytes. It means
1385 // we have missed accounting some objects during the actual marking.
1386 if (exp_marked_bytes > act_marked_bytes) {
1387 if (_verbose) {
1388 gclog_or_tty->print_cr("Region %u: marked bytes mismatch: "
1389 "expected: " SIZE_FORMAT ", actual: " SIZE_FORMAT,
1390 hr->hrs_index(), exp_marked_bytes, act_marked_bytes);
1391 }
1392 failures += 1;
1393 }
1395 // Verify the bit, for this region, in the actual and expected
1396 // (which was just calculated) region bit maps.
1397 // We're not OK if the bit in the calculated expected region
1398 // bitmap is set and the bit in the actual region bitmap is not.
1399 BitMap::idx_t index = (BitMap::idx_t) hr->hrs_index();
1401 bool expected = _exp_region_bm->at(index);
1402 bool actual = _region_bm->at(index);
1403 if (expected && !actual) {
1404 if (_verbose) {
1405 gclog_or_tty->print_cr("Region %u: region bitmap mismatch: "
1406 "expected: %s, actual: %s",
1407 hr->hrs_index(),
1408 BOOL_TO_STR(expected), BOOL_TO_STR(actual));
1409 }
1410 failures += 1;
1411 }
1413 // Verify that the card bit maps for the cards spanned by the current
1414 // region match. We have an error if we have a set bit in the expected
1415 // bit map and the corresponding bit in the actual bitmap is not set.
1417 BitMap::idx_t start_idx = _cm->card_bitmap_index_for(hr->bottom());
1418 BitMap::idx_t end_idx = _cm->card_bitmap_index_for(hr->top());
1420 for (BitMap::idx_t i = start_idx; i < end_idx; i+=1) {
1421 expected = _exp_card_bm->at(i);
1422 actual = _card_bm->at(i);
1424 if (expected && !actual) {
1425 if (_verbose) {
1426 gclog_or_tty->print_cr("Region %u: card bitmap mismatch at " SIZE_FORMAT ": "
1427 "expected: %s, actual: %s",
1428 hr->hrs_index(), i,
1429 BOOL_TO_STR(expected), BOOL_TO_STR(actual));
1430 }
1431 failures += 1;
1432 }
1433 }
1435 if (failures > 0 && _verbose) {
1436 gclog_or_tty->print_cr("Region " HR_FORMAT ", ntams: " PTR_FORMAT ", "
1437 "marked_bytes: calc/actual " SIZE_FORMAT "/" SIZE_FORMAT,
1438 HR_FORMAT_PARAMS(hr), hr->next_top_at_mark_start(),
1439 _calc_cl.region_marked_bytes(), hr->next_marked_bytes());
1440 }
1442 _failures += failures;
1444 // We could stop iteration over the heap when we
1445 // find the first violating region by returning true.
1446 return false;
1447 }
1448 };
1451 class G1ParVerifyFinalCountTask: public AbstractGangTask {
1452 protected:
1453 G1CollectedHeap* _g1h;
1454 ConcurrentMark* _cm;
1455 BitMap* _actual_region_bm;
1456 BitMap* _actual_card_bm;
1458 uint _n_workers;
1460 BitMap* _expected_region_bm;
1461 BitMap* _expected_card_bm;
1463 int _failures;
1464 bool _verbose;
1466 public:
1467 G1ParVerifyFinalCountTask(G1CollectedHeap* g1h,
1468 BitMap* region_bm, BitMap* card_bm,
1469 BitMap* expected_region_bm, BitMap* expected_card_bm)
1470 : AbstractGangTask("G1 verify final counting"),
1471 _g1h(g1h), _cm(_g1h->concurrent_mark()),
1472 _actual_region_bm(region_bm), _actual_card_bm(card_bm),
1473 _expected_region_bm(expected_region_bm), _expected_card_bm(expected_card_bm),
1474 _failures(0), _verbose(false),
1475 _n_workers(0) {
1476 assert(VerifyDuringGC, "don't call this otherwise");
1478 // Use the value already set as the number of active threads
1479 // in the call to run_task().
1480 if (G1CollectedHeap::use_parallel_gc_threads()) {
1481 assert( _g1h->workers()->active_workers() > 0,
1482 "Should have been previously set");
1483 _n_workers = _g1h->workers()->active_workers();
1484 } else {
1485 _n_workers = 1;
1486 }
1488 assert(_expected_card_bm->size() == _actual_card_bm->size(), "sanity");
1489 assert(_expected_region_bm->size() == _actual_region_bm->size(), "sanity");
1491 _verbose = _cm->verbose_medium();
1492 }
1494 void work(uint worker_id) {
1495 assert(worker_id < _n_workers, "invariant");
1497 VerifyLiveObjectDataHRClosure verify_cl(_cm,
1498 _actual_region_bm, _actual_card_bm,
1499 _expected_region_bm,
1500 _expected_card_bm,
1501 _verbose);
1503 if (G1CollectedHeap::use_parallel_gc_threads()) {
1504 _g1h->heap_region_par_iterate_chunked(&verify_cl,
1505 worker_id,
1506 _n_workers,
1507 HeapRegion::VerifyCountClaimValue);
1508 } else {
1509 _g1h->heap_region_iterate(&verify_cl);
1510 }
1512 Atomic::add(verify_cl.failures(), &_failures);
1513 }
1515 int failures() const { return _failures; }
1516 };
1518 // Closure that finalizes the liveness counting data.
1519 // Used during the cleanup pause.
1520 // Sets the bits corresponding to the interval [NTAMS, top]
1521 // (which contains the implicitly live objects) in the
1522 // card liveness bitmap. Also sets the bit for each region,
1523 // containing live data, in the region liveness bitmap.
1525 class FinalCountDataUpdateClosure: public CMCountDataClosureBase {
1526 public:
1527 FinalCountDataUpdateClosure(ConcurrentMark* cm,
1528 BitMap* region_bm,
1529 BitMap* card_bm) :
1530 CMCountDataClosureBase(cm, region_bm, card_bm) { }
1532 bool doHeapRegion(HeapRegion* hr) {
1534 if (hr->continuesHumongous()) {
1535 // We will ignore these here and process them when their
1536 // associated "starts humongous" region is processed (see
1537 // set_bit_for_heap_region()). Note that we cannot rely on their
1538 // associated "starts humongous" region to have their bit set to
1539 // 1 since, due to the region chunking in the parallel region
1540 // iteration, a "continues humongous" region might be visited
1541 // before its associated "starts humongous".
1542 return false;
1543 }
1545 HeapWord* ntams = hr->next_top_at_mark_start();
1546 HeapWord* top = hr->top();
1548 assert(hr->bottom() <= ntams && ntams <= hr->end(), "Preconditions.");
1550 // Mark the allocated-since-marking portion...
1551 if (ntams < top) {
1552 // This definitely means the region has live objects.
1553 set_bit_for_region(hr);
1554 }
1556 // Now set the bits for [ntams, top]
1557 BitMap::idx_t start_idx = _cm->card_bitmap_index_for(ntams);
1558 BitMap::idx_t last_idx = _cm->card_bitmap_index_for(top);
1559 set_card_bitmap_range(start_idx, last_idx);
1561 // Set the bit for the region if it contains live data
1562 if (hr->next_marked_bytes() > 0) {
1563 set_bit_for_region(hr);
1564 }
1566 return false;
1567 }
1568 };
1570 class G1ParFinalCountTask: public AbstractGangTask {
1571 protected:
1572 G1CollectedHeap* _g1h;
1573 ConcurrentMark* _cm;
1574 BitMap* _actual_region_bm;
1575 BitMap* _actual_card_bm;
1577 uint _n_workers;
1579 public:
1580 G1ParFinalCountTask(G1CollectedHeap* g1h, BitMap* region_bm, BitMap* card_bm)
1581 : AbstractGangTask("G1 final counting"),
1582 _g1h(g1h), _cm(_g1h->concurrent_mark()),
1583 _actual_region_bm(region_bm), _actual_card_bm(card_bm),
1584 _n_workers(0) {
1585 // Use the value already set as the number of active threads
1586 // in the call to run_task().
1587 if (G1CollectedHeap::use_parallel_gc_threads()) {
1588 assert( _g1h->workers()->active_workers() > 0,
1589 "Should have been previously set");
1590 _n_workers = _g1h->workers()->active_workers();
1591 } else {
1592 _n_workers = 1;
1593 }
1594 }
1596 void work(uint worker_id) {
1597 assert(worker_id < _n_workers, "invariant");
1599 FinalCountDataUpdateClosure final_update_cl(_cm,
1600 _actual_region_bm,
1601 _actual_card_bm);
1603 if (G1CollectedHeap::use_parallel_gc_threads()) {
1604 _g1h->heap_region_par_iterate_chunked(&final_update_cl,
1605 worker_id,
1606 _n_workers,
1607 HeapRegion::FinalCountClaimValue);
1608 } else {
1609 _g1h->heap_region_iterate(&final_update_cl);
1610 }
1611 }
1612 };
1614 class G1ParNoteEndTask;
1616 class G1NoteEndOfConcMarkClosure : public HeapRegionClosure {
1617 G1CollectedHeap* _g1;
1618 int _worker_num;
1619 size_t _max_live_bytes;
1620 uint _regions_claimed;
1621 size_t _freed_bytes;
1622 FreeRegionList* _local_cleanup_list;
1623 OldRegionSet* _old_proxy_set;
1624 HumongousRegionSet* _humongous_proxy_set;
1625 HRRSCleanupTask* _hrrs_cleanup_task;
1626 double _claimed_region_time;
1627 double _max_region_time;
1629 public:
1630 G1NoteEndOfConcMarkClosure(G1CollectedHeap* g1,
1631 int worker_num,
1632 FreeRegionList* local_cleanup_list,
1633 OldRegionSet* old_proxy_set,
1634 HumongousRegionSet* humongous_proxy_set,
1635 HRRSCleanupTask* hrrs_cleanup_task) :
1636 _g1(g1), _worker_num(worker_num),
1637 _max_live_bytes(0), _regions_claimed(0),
1638 _freed_bytes(0),
1639 _claimed_region_time(0.0), _max_region_time(0.0),
1640 _local_cleanup_list(local_cleanup_list),
1641 _old_proxy_set(old_proxy_set),
1642 _humongous_proxy_set(humongous_proxy_set),
1643 _hrrs_cleanup_task(hrrs_cleanup_task) { }
1645 size_t freed_bytes() { return _freed_bytes; }
1647 bool doHeapRegion(HeapRegion *hr) {
1648 // We use a claim value of zero here because all regions
1649 // were claimed with value 1 in the FinalCount task.
1650 hr->reset_gc_time_stamp();
1651 if (!hr->continuesHumongous()) {
1652 double start = os::elapsedTime();
1653 _regions_claimed++;
1654 hr->note_end_of_marking();
1655 _max_live_bytes += hr->max_live_bytes();
1656 _g1->free_region_if_empty(hr,
1657 &_freed_bytes,
1658 _local_cleanup_list,
1659 _old_proxy_set,
1660 _humongous_proxy_set,
1661 _hrrs_cleanup_task,
1662 true /* par */);
1663 double region_time = (os::elapsedTime() - start);
1664 _claimed_region_time += region_time;
1665 if (region_time > _max_region_time) {
1666 _max_region_time = region_time;
1667 }
1668 }
1669 return false;
1670 }
1672 size_t max_live_bytes() { return _max_live_bytes; }
1673 uint regions_claimed() { return _regions_claimed; }
1674 double claimed_region_time_sec() { return _claimed_region_time; }
1675 double max_region_time_sec() { return _max_region_time; }
1676 };
1678 class G1ParNoteEndTask: public AbstractGangTask {
1679 friend class G1NoteEndOfConcMarkClosure;
1681 protected:
1682 G1CollectedHeap* _g1h;
1683 size_t _max_live_bytes;
1684 size_t _freed_bytes;
1685 FreeRegionList* _cleanup_list;
1687 public:
1688 G1ParNoteEndTask(G1CollectedHeap* g1h,
1689 FreeRegionList* cleanup_list) :
1690 AbstractGangTask("G1 note end"), _g1h(g1h),
1691 _max_live_bytes(0), _freed_bytes(0), _cleanup_list(cleanup_list) { }
1693 void work(uint worker_id) {
1694 double start = os::elapsedTime();
1695 FreeRegionList local_cleanup_list("Local Cleanup List");
1696 OldRegionSet old_proxy_set("Local Cleanup Old Proxy Set");
1697 HumongousRegionSet humongous_proxy_set("Local Cleanup Humongous Proxy Set");
1698 HRRSCleanupTask hrrs_cleanup_task;
1699 G1NoteEndOfConcMarkClosure g1_note_end(_g1h, worker_id, &local_cleanup_list,
1700 &old_proxy_set,
1701 &humongous_proxy_set,
1702 &hrrs_cleanup_task);
1703 if (G1CollectedHeap::use_parallel_gc_threads()) {
1704 _g1h->heap_region_par_iterate_chunked(&g1_note_end, worker_id,
1705 _g1h->workers()->active_workers(),
1706 HeapRegion::NoteEndClaimValue);
1707 } else {
1708 _g1h->heap_region_iterate(&g1_note_end);
1709 }
1710 assert(g1_note_end.complete(), "Shouldn't have yielded!");
1712 // Now update the lists
1713 _g1h->update_sets_after_freeing_regions(g1_note_end.freed_bytes(),
1714 NULL /* free_list */,
1715 &old_proxy_set,
1716 &humongous_proxy_set,
1717 true /* par */);
1718 {
1719 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
1720 _max_live_bytes += g1_note_end.max_live_bytes();
1721 _freed_bytes += g1_note_end.freed_bytes();
1723 // If we iterate over the global cleanup list at the end of
1724 // cleanup to do this printing we will not guarantee to only
1725 // generate output for the newly-reclaimed regions (the list
1726 // might not be empty at the beginning of cleanup; we might
1727 // still be working on its previous contents). So we do the
1728 // printing here, before we append the new regions to the global
1729 // cleanup list.
1731 G1HRPrinter* hr_printer = _g1h->hr_printer();
1732 if (hr_printer->is_active()) {
1733 HeapRegionLinkedListIterator iter(&local_cleanup_list);
1734 while (iter.more_available()) {
1735 HeapRegion* hr = iter.get_next();
1736 hr_printer->cleanup(hr);
1737 }
1738 }
1740 _cleanup_list->add_as_tail(&local_cleanup_list);
1741 assert(local_cleanup_list.is_empty(), "post-condition");
1743 HeapRegionRemSet::finish_cleanup_task(&hrrs_cleanup_task);
1744 }
1745 }
1746 size_t max_live_bytes() { return _max_live_bytes; }
1747 size_t freed_bytes() { return _freed_bytes; }
1748 };
1750 class G1ParScrubRemSetTask: public AbstractGangTask {
1751 protected:
1752 G1RemSet* _g1rs;
1753 BitMap* _region_bm;
1754 BitMap* _card_bm;
1755 public:
1756 G1ParScrubRemSetTask(G1CollectedHeap* g1h,
1757 BitMap* region_bm, BitMap* card_bm) :
1758 AbstractGangTask("G1 ScrubRS"), _g1rs(g1h->g1_rem_set()),
1759 _region_bm(region_bm), _card_bm(card_bm) { }
1761 void work(uint worker_id) {
1762 if (G1CollectedHeap::use_parallel_gc_threads()) {
1763 _g1rs->scrub_par(_region_bm, _card_bm, worker_id,
1764 HeapRegion::ScrubRemSetClaimValue);
1765 } else {
1766 _g1rs->scrub(_region_bm, _card_bm);
1767 }
1768 }
1770 };
1772 void ConcurrentMark::cleanup() {
1773 // world is stopped at this checkpoint
1774 assert(SafepointSynchronize::is_at_safepoint(),
1775 "world should be stopped");
1776 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1778 // If a full collection has happened, we shouldn't do this.
1779 if (has_aborted()) {
1780 g1h->set_marking_complete(); // So bitmap clearing isn't confused
1781 return;
1782 }
1784 HRSPhaseSetter x(HRSPhaseCleanup);
1785 g1h->verify_region_sets_optional();
1787 if (VerifyDuringGC) {
1788 HandleMark hm; // handle scope
1789 gclog_or_tty->print(" VerifyDuringGC:(before)");
1790 Universe::heap()->prepare_for_verify();
1791 Universe::verify(/* silent */ false,
1792 /* option */ VerifyOption_G1UsePrevMarking);
1793 }
1795 G1CollectorPolicy* g1p = G1CollectedHeap::heap()->g1_policy();
1796 g1p->record_concurrent_mark_cleanup_start();
1798 double start = os::elapsedTime();
1800 HeapRegionRemSet::reset_for_cleanup_tasks();
1802 uint n_workers;
1804 // Do counting once more with the world stopped for good measure.
1805 G1ParFinalCountTask g1_par_count_task(g1h, &_region_bm, &_card_bm);
1807 if (G1CollectedHeap::use_parallel_gc_threads()) {
1808 assert(g1h->check_heap_region_claim_values(HeapRegion::InitialClaimValue),
1809 "sanity check");
1811 g1h->set_par_threads();
1812 n_workers = g1h->n_par_threads();
1813 assert(g1h->n_par_threads() == n_workers,
1814 "Should not have been reset");
1815 g1h->workers()->run_task(&g1_par_count_task);
1816 // Done with the parallel phase so reset to 0.
1817 g1h->set_par_threads(0);
1819 assert(g1h->check_heap_region_claim_values(HeapRegion::FinalCountClaimValue),
1820 "sanity check");
1821 } else {
1822 n_workers = 1;
1823 g1_par_count_task.work(0);
1824 }
1826 if (VerifyDuringGC) {
1827 // Verify that the counting data accumulated during marking matches
1828 // that calculated by walking the marking bitmap.
1830 // Bitmaps to hold expected values
1831 BitMap expected_region_bm(_region_bm.size(), false);
1832 BitMap expected_card_bm(_card_bm.size(), false);
1834 G1ParVerifyFinalCountTask g1_par_verify_task(g1h,
1835 &_region_bm,
1836 &_card_bm,
1837 &expected_region_bm,
1838 &expected_card_bm);
1840 if (G1CollectedHeap::use_parallel_gc_threads()) {
1841 g1h->set_par_threads((int)n_workers);
1842 g1h->workers()->run_task(&g1_par_verify_task);
1843 // Done with the parallel phase so reset to 0.
1844 g1h->set_par_threads(0);
1846 assert(g1h->check_heap_region_claim_values(HeapRegion::VerifyCountClaimValue),
1847 "sanity check");
1848 } else {
1849 g1_par_verify_task.work(0);
1850 }
1852 guarantee(g1_par_verify_task.failures() == 0, "Unexpected accounting failures");
1853 }
1855 size_t start_used_bytes = g1h->used();
1856 g1h->set_marking_complete();
1858 double count_end = os::elapsedTime();
1859 double this_final_counting_time = (count_end - start);
1860 _total_counting_time += this_final_counting_time;
1862 if (G1PrintRegionLivenessInfo) {
1863 G1PrintRegionLivenessInfoClosure cl(gclog_or_tty, "Post-Marking");
1864 _g1h->heap_region_iterate(&cl);
1865 }
1867 // Install newly created mark bitMap as "prev".
1868 swapMarkBitMaps();
1870 g1h->reset_gc_time_stamp();
1872 // Note end of marking in all heap regions.
1873 G1ParNoteEndTask g1_par_note_end_task(g1h, &_cleanup_list);
1874 if (G1CollectedHeap::use_parallel_gc_threads()) {
1875 g1h->set_par_threads((int)n_workers);
1876 g1h->workers()->run_task(&g1_par_note_end_task);
1877 g1h->set_par_threads(0);
1879 assert(g1h->check_heap_region_claim_values(HeapRegion::NoteEndClaimValue),
1880 "sanity check");
1881 } else {
1882 g1_par_note_end_task.work(0);
1883 }
1885 if (!cleanup_list_is_empty()) {
1886 // The cleanup list is not empty, so we'll have to process it
1887 // concurrently. Notify anyone else that might be wanting free
1888 // regions that there will be more free regions coming soon.
1889 g1h->set_free_regions_coming();
1890 }
1892 // call below, since it affects the metric by which we sort the heap
1893 // regions.
1894 if (G1ScrubRemSets) {
1895 double rs_scrub_start = os::elapsedTime();
1896 G1ParScrubRemSetTask g1_par_scrub_rs_task(g1h, &_region_bm, &_card_bm);
1897 if (G1CollectedHeap::use_parallel_gc_threads()) {
1898 g1h->set_par_threads((int)n_workers);
1899 g1h->workers()->run_task(&g1_par_scrub_rs_task);
1900 g1h->set_par_threads(0);
1902 assert(g1h->check_heap_region_claim_values(
1903 HeapRegion::ScrubRemSetClaimValue),
1904 "sanity check");
1905 } else {
1906 g1_par_scrub_rs_task.work(0);
1907 }
1909 double rs_scrub_end = os::elapsedTime();
1910 double this_rs_scrub_time = (rs_scrub_end - rs_scrub_start);
1911 _total_rs_scrub_time += this_rs_scrub_time;
1912 }
1914 // this will also free any regions totally full of garbage objects,
1915 // and sort the regions.
1916 g1h->g1_policy()->record_concurrent_mark_cleanup_end((int)n_workers);
1918 // Statistics.
1919 double end = os::elapsedTime();
1920 _cleanup_times.add((end - start) * 1000.0);
1922 if (G1Log::fine()) {
1923 g1h->print_size_transition(gclog_or_tty,
1924 start_used_bytes,
1925 g1h->used(),
1926 g1h->capacity());
1927 }
1929 // Clean up will have freed any regions completely full of garbage.
1930 // Update the soft reference policy with the new heap occupancy.
1931 Universe::update_heap_info_at_gc();
1933 // We need to make this be a "collection" so any collection pause that
1934 // races with it goes around and waits for completeCleanup to finish.
1935 g1h->increment_total_collections();
1937 // We reclaimed old regions so we should calculate the sizes to make
1938 // sure we update the old gen/space data.
1939 g1h->g1mm()->update_sizes();
1941 if (VerifyDuringGC) {
1942 HandleMark hm; // handle scope
1943 gclog_or_tty->print(" VerifyDuringGC:(after)");
1944 Universe::heap()->prepare_for_verify();
1945 Universe::verify(/* silent */ false,
1946 /* option */ VerifyOption_G1UsePrevMarking);
1947 }
1949 g1h->verify_region_sets_optional();
1950 }
1952 void ConcurrentMark::completeCleanup() {
1953 if (has_aborted()) return;
1955 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1957 _cleanup_list.verify_optional();
1958 FreeRegionList tmp_free_list("Tmp Free List");
1960 if (G1ConcRegionFreeingVerbose) {
1961 gclog_or_tty->print_cr("G1ConcRegionFreeing [complete cleanup] : "
1962 "cleanup list has %u entries",
1963 _cleanup_list.length());
1964 }
1966 // Noone else should be accessing the _cleanup_list at this point,
1967 // so it's not necessary to take any locks
1968 while (!_cleanup_list.is_empty()) {
1969 HeapRegion* hr = _cleanup_list.remove_head();
1970 assert(hr != NULL, "the list was not empty");
1971 hr->par_clear();
1972 tmp_free_list.add_as_tail(hr);
1974 // Instead of adding one region at a time to the secondary_free_list,
1975 // we accumulate them in the local list and move them a few at a
1976 // time. This also cuts down on the number of notify_all() calls
1977 // we do during this process. We'll also append the local list when
1978 // _cleanup_list is empty (which means we just removed the last
1979 // region from the _cleanup_list).
1980 if ((tmp_free_list.length() % G1SecondaryFreeListAppendLength == 0) ||
1981 _cleanup_list.is_empty()) {
1982 if (G1ConcRegionFreeingVerbose) {
1983 gclog_or_tty->print_cr("G1ConcRegionFreeing [complete cleanup] : "
1984 "appending %u entries to the secondary_free_list, "
1985 "cleanup list still has %u entries",
1986 tmp_free_list.length(),
1987 _cleanup_list.length());
1988 }
1990 {
1991 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
1992 g1h->secondary_free_list_add_as_tail(&tmp_free_list);
1993 SecondaryFreeList_lock->notify_all();
1994 }
1996 if (G1StressConcRegionFreeing) {
1997 for (uintx i = 0; i < G1StressConcRegionFreeingDelayMillis; ++i) {
1998 os::sleep(Thread::current(), (jlong) 1, false);
1999 }
2000 }
2001 }
2002 }
2003 assert(tmp_free_list.is_empty(), "post-condition");
2004 }
2006 // Support closures for reference procssing in G1
2008 bool G1CMIsAliveClosure::do_object_b(oop obj) {
2009 HeapWord* addr = (HeapWord*)obj;
2010 return addr != NULL &&
2011 (!_g1->is_in_g1_reserved(addr) || !_g1->is_obj_ill(obj));
2012 }
2014 class G1CMKeepAliveClosure: public OopClosure {
2015 G1CollectedHeap* _g1;
2016 ConcurrentMark* _cm;
2017 public:
2018 G1CMKeepAliveClosure(G1CollectedHeap* g1, ConcurrentMark* cm) :
2019 _g1(g1), _cm(cm) {
2020 assert(Thread::current()->is_VM_thread(), "otherwise fix worker id");
2021 }
2023 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
2024 virtual void do_oop( oop* p) { do_oop_work(p); }
2026 template <class T> void do_oop_work(T* p) {
2027 oop obj = oopDesc::load_decode_heap_oop(p);
2028 HeapWord* addr = (HeapWord*)obj;
2030 if (_cm->verbose_high()) {
2031 gclog_or_tty->print_cr("\t[0] we're looking at location "
2032 "*"PTR_FORMAT" = "PTR_FORMAT,
2033 p, (void*) obj);
2034 }
2036 if (_g1->is_in_g1_reserved(addr) && _g1->is_obj_ill(obj)) {
2037 _cm->mark_and_count(obj);
2038 _cm->mark_stack_push(obj);
2039 }
2040 }
2041 };
2043 class G1CMDrainMarkingStackClosure: public VoidClosure {
2044 ConcurrentMark* _cm;
2045 CMMarkStack* _markStack;
2046 G1CMKeepAliveClosure* _oopClosure;
2047 public:
2048 G1CMDrainMarkingStackClosure(ConcurrentMark* cm, CMMarkStack* markStack,
2049 G1CMKeepAliveClosure* oopClosure) :
2050 _cm(cm),
2051 _markStack(markStack),
2052 _oopClosure(oopClosure) { }
2054 void do_void() {
2055 _markStack->drain((OopClosure*)_oopClosure, _cm->nextMarkBitMap(), false);
2056 }
2057 };
2059 // 'Keep Alive' closure used by parallel reference processing.
2060 // An instance of this closure is used in the parallel reference processing
2061 // code rather than an instance of G1CMKeepAliveClosure. We could have used
2062 // the G1CMKeepAliveClosure as it is MT-safe. Also reference objects are
2063 // placed on to discovered ref lists once so we can mark and push with no
2064 // need to check whether the object has already been marked. Using the
2065 // G1CMKeepAliveClosure would mean, however, having all the worker threads
2066 // operating on the global mark stack. This means that an individual
2067 // worker would be doing lock-free pushes while it processes its own
2068 // discovered ref list followed by drain call. If the discovered ref lists
2069 // are unbalanced then this could cause interference with the other
2070 // workers. Using a CMTask (and its embedded local data structures)
2071 // avoids that potential interference.
2072 class G1CMParKeepAliveAndDrainClosure: public OopClosure {
2073 ConcurrentMark* _cm;
2074 CMTask* _task;
2075 int _ref_counter_limit;
2076 int _ref_counter;
2077 public:
2078 G1CMParKeepAliveAndDrainClosure(ConcurrentMark* cm, CMTask* task) :
2079 _cm(cm), _task(task),
2080 _ref_counter_limit(G1RefProcDrainInterval) {
2081 assert(_ref_counter_limit > 0, "sanity");
2082 _ref_counter = _ref_counter_limit;
2083 }
2085 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
2086 virtual void do_oop( oop* p) { do_oop_work(p); }
2088 template <class T> void do_oop_work(T* p) {
2089 if (!_cm->has_overflown()) {
2090 oop obj = oopDesc::load_decode_heap_oop(p);
2091 if (_cm->verbose_high()) {
2092 gclog_or_tty->print_cr("\t[%d] we're looking at location "
2093 "*"PTR_FORMAT" = "PTR_FORMAT,
2094 _task->task_id(), p, (void*) obj);
2095 }
2097 _task->deal_with_reference(obj);
2098 _ref_counter--;
2100 if (_ref_counter == 0) {
2101 // We have dealt with _ref_counter_limit references, pushing them and objects
2102 // reachable from them on to the local stack (and possibly the global stack).
2103 // Call do_marking_step() to process these entries. We call the routine in a
2104 // loop, which we'll exit if there's nothing more to do (i.e. we're done
2105 // with the entries that we've pushed as a result of the deal_with_reference
2106 // calls above) or we overflow.
2107 // Note: CMTask::do_marking_step() can set the CMTask::has_aborted() flag
2108 // while there may still be some work to do. (See the comment at the
2109 // beginning of CMTask::do_marking_step() for those conditions - one of which
2110 // is reaching the specified time target.) It is only when
2111 // CMTask::do_marking_step() returns without setting the has_aborted() flag
2112 // that the marking has completed.
2113 do {
2114 double mark_step_duration_ms = G1ConcMarkStepDurationMillis;
2115 _task->do_marking_step(mark_step_duration_ms,
2116 false /* do_stealing */,
2117 false /* do_termination */);
2118 } while (_task->has_aborted() && !_cm->has_overflown());
2119 _ref_counter = _ref_counter_limit;
2120 }
2121 } else {
2122 if (_cm->verbose_high()) {
2123 gclog_or_tty->print_cr("\t[%d] CM Overflow", _task->task_id());
2124 }
2125 }
2126 }
2127 };
2129 class G1CMParDrainMarkingStackClosure: public VoidClosure {
2130 ConcurrentMark* _cm;
2131 CMTask* _task;
2132 public:
2133 G1CMParDrainMarkingStackClosure(ConcurrentMark* cm, CMTask* task) :
2134 _cm(cm), _task(task) { }
2136 void do_void() {
2137 do {
2138 if (_cm->verbose_high()) {
2139 gclog_or_tty->print_cr("\t[%d] Drain: Calling do marking_step",
2140 _task->task_id());
2141 }
2143 // We call CMTask::do_marking_step() to completely drain the local and
2144 // global marking stacks. The routine is called in a loop, which we'll
2145 // exit if there's nothing more to do (i.e. we'completely drained the
2146 // entries that were pushed as a result of applying the
2147 // G1CMParKeepAliveAndDrainClosure to the entries on the discovered ref
2148 // lists above) or we overflow the global marking stack.
2149 // Note: CMTask::do_marking_step() can set the CMTask::has_aborted() flag
2150 // while there may still be some work to do. (See the comment at the
2151 // beginning of CMTask::do_marking_step() for those conditions - one of which
2152 // is reaching the specified time target.) It is only when
2153 // CMTask::do_marking_step() returns without setting the has_aborted() flag
2154 // that the marking has completed.
2156 _task->do_marking_step(1000000000.0 /* something very large */,
2157 true /* do_stealing */,
2158 true /* do_termination */);
2159 } while (_task->has_aborted() && !_cm->has_overflown());
2160 }
2161 };
2163 // Implementation of AbstractRefProcTaskExecutor for parallel
2164 // reference processing at the end of G1 concurrent marking
2166 class G1CMRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
2167 private:
2168 G1CollectedHeap* _g1h;
2169 ConcurrentMark* _cm;
2170 WorkGang* _workers;
2171 int _active_workers;
2173 public:
2174 G1CMRefProcTaskExecutor(G1CollectedHeap* g1h,
2175 ConcurrentMark* cm,
2176 WorkGang* workers,
2177 int n_workers) :
2178 _g1h(g1h), _cm(cm),
2179 _workers(workers), _active_workers(n_workers) { }
2181 // Executes the given task using concurrent marking worker threads.
2182 virtual void execute(ProcessTask& task);
2183 virtual void execute(EnqueueTask& task);
2184 };
2186 class G1CMRefProcTaskProxy: public AbstractGangTask {
2187 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
2188 ProcessTask& _proc_task;
2189 G1CollectedHeap* _g1h;
2190 ConcurrentMark* _cm;
2192 public:
2193 G1CMRefProcTaskProxy(ProcessTask& proc_task,
2194 G1CollectedHeap* g1h,
2195 ConcurrentMark* cm) :
2196 AbstractGangTask("Process reference objects in parallel"),
2197 _proc_task(proc_task), _g1h(g1h), _cm(cm) { }
2199 virtual void work(uint worker_id) {
2200 CMTask* marking_task = _cm->task(worker_id);
2201 G1CMIsAliveClosure g1_is_alive(_g1h);
2202 G1CMParKeepAliveAndDrainClosure g1_par_keep_alive(_cm, marking_task);
2203 G1CMParDrainMarkingStackClosure g1_par_drain(_cm, marking_task);
2205 _proc_task.work(worker_id, g1_is_alive, g1_par_keep_alive, g1_par_drain);
2206 }
2207 };
2209 void G1CMRefProcTaskExecutor::execute(ProcessTask& proc_task) {
2210 assert(_workers != NULL, "Need parallel worker threads.");
2212 G1CMRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _cm);
2214 // We need to reset the phase for each task execution so that
2215 // the termination protocol of CMTask::do_marking_step works.
2216 _cm->set_phase(_active_workers, false /* concurrent */);
2217 _g1h->set_par_threads(_active_workers);
2218 _workers->run_task(&proc_task_proxy);
2219 _g1h->set_par_threads(0);
2220 }
2222 class G1CMRefEnqueueTaskProxy: public AbstractGangTask {
2223 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
2224 EnqueueTask& _enq_task;
2226 public:
2227 G1CMRefEnqueueTaskProxy(EnqueueTask& enq_task) :
2228 AbstractGangTask("Enqueue reference objects in parallel"),
2229 _enq_task(enq_task) { }
2231 virtual void work(uint worker_id) {
2232 _enq_task.work(worker_id);
2233 }
2234 };
2236 void G1CMRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
2237 assert(_workers != NULL, "Need parallel worker threads.");
2239 G1CMRefEnqueueTaskProxy enq_task_proxy(enq_task);
2241 _g1h->set_par_threads(_active_workers);
2242 _workers->run_task(&enq_task_proxy);
2243 _g1h->set_par_threads(0);
2244 }
2246 void ConcurrentMark::weakRefsWork(bool clear_all_soft_refs) {
2247 ResourceMark rm;
2248 HandleMark hm;
2250 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2252 // Is alive closure.
2253 G1CMIsAliveClosure g1_is_alive(g1h);
2255 // Inner scope to exclude the cleaning of the string and symbol
2256 // tables from the displayed time.
2257 {
2258 if (G1Log::finer()) {
2259 gclog_or_tty->put(' ');
2260 }
2261 TraceTime t("GC ref-proc", G1Log::finer(), false, gclog_or_tty);
2263 ReferenceProcessor* rp = g1h->ref_processor_cm();
2265 // See the comment in G1CollectedHeap::ref_processing_init()
2266 // about how reference processing currently works in G1.
2268 // Process weak references.
2269 rp->setup_policy(clear_all_soft_refs);
2270 assert(_markStack.isEmpty(), "mark stack should be empty");
2272 G1CMKeepAliveClosure g1_keep_alive(g1h, this);
2273 G1CMDrainMarkingStackClosure
2274 g1_drain_mark_stack(this, &_markStack, &g1_keep_alive);
2276 // We use the work gang from the G1CollectedHeap and we utilize all
2277 // the worker threads.
2278 uint active_workers = g1h->workers() ? g1h->workers()->active_workers() : 1U;
2279 active_workers = MAX2(MIN2(active_workers, _max_task_num), 1U);
2281 G1CMRefProcTaskExecutor par_task_executor(g1h, this,
2282 g1h->workers(), active_workers);
2284 if (rp->processing_is_mt()) {
2285 // Set the degree of MT here. If the discovery is done MT, there
2286 // may have been a different number of threads doing the discovery
2287 // and a different number of discovered lists may have Ref objects.
2288 // That is OK as long as the Reference lists are balanced (see
2289 // balance_all_queues() and balance_queues()).
2290 rp->set_active_mt_degree(active_workers);
2292 rp->process_discovered_references(&g1_is_alive,
2293 &g1_keep_alive,
2294 &g1_drain_mark_stack,
2295 &par_task_executor);
2297 // The work routines of the parallel keep_alive and drain_marking_stack
2298 // will set the has_overflown flag if we overflow the global marking
2299 // stack.
2300 } else {
2301 rp->process_discovered_references(&g1_is_alive,
2302 &g1_keep_alive,
2303 &g1_drain_mark_stack,
2304 NULL);
2305 }
2307 assert(_markStack.overflow() || _markStack.isEmpty(),
2308 "mark stack should be empty (unless it overflowed)");
2309 if (_markStack.overflow()) {
2310 // Should have been done already when we tried to push an
2311 // entry on to the global mark stack. But let's do it again.
2312 set_has_overflown();
2313 }
2315 if (rp->processing_is_mt()) {
2316 assert(rp->num_q() == active_workers, "why not");
2317 rp->enqueue_discovered_references(&par_task_executor);
2318 } else {
2319 rp->enqueue_discovered_references();
2320 }
2322 rp->verify_no_references_recorded();
2323 assert(!rp->discovery_enabled(), "Post condition");
2324 }
2326 // Now clean up stale oops in StringTable
2327 StringTable::unlink(&g1_is_alive);
2328 // Clean up unreferenced symbols in symbol table.
2329 SymbolTable::unlink();
2330 }
2332 void ConcurrentMark::swapMarkBitMaps() {
2333 CMBitMapRO* temp = _prevMarkBitMap;
2334 _prevMarkBitMap = (CMBitMapRO*)_nextMarkBitMap;
2335 _nextMarkBitMap = (CMBitMap*) temp;
2336 }
2338 class CMRemarkTask: public AbstractGangTask {
2339 private:
2340 ConcurrentMark *_cm;
2342 public:
2343 void work(uint worker_id) {
2344 // Since all available tasks are actually started, we should
2345 // only proceed if we're supposed to be actived.
2346 if (worker_id < _cm->active_tasks()) {
2347 CMTask* task = _cm->task(worker_id);
2348 task->record_start_time();
2349 do {
2350 task->do_marking_step(1000000000.0 /* something very large */,
2351 true /* do_stealing */,
2352 true /* do_termination */);
2353 } while (task->has_aborted() && !_cm->has_overflown());
2354 // If we overflow, then we do not want to restart. We instead
2355 // want to abort remark and do concurrent marking again.
2356 task->record_end_time();
2357 }
2358 }
2360 CMRemarkTask(ConcurrentMark* cm, int active_workers) :
2361 AbstractGangTask("Par Remark"), _cm(cm) {
2362 _cm->terminator()->reset_for_reuse(active_workers);
2363 }
2364 };
2366 void ConcurrentMark::checkpointRootsFinalWork() {
2367 ResourceMark rm;
2368 HandleMark hm;
2369 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2371 g1h->ensure_parsability(false);
2373 if (G1CollectedHeap::use_parallel_gc_threads()) {
2374 G1CollectedHeap::StrongRootsScope srs(g1h);
2375 // this is remark, so we'll use up all active threads
2376 uint active_workers = g1h->workers()->active_workers();
2377 if (active_workers == 0) {
2378 assert(active_workers > 0, "Should have been set earlier");
2379 active_workers = (uint) ParallelGCThreads;
2380 g1h->workers()->set_active_workers(active_workers);
2381 }
2382 set_phase(active_workers, false /* concurrent */);
2383 // Leave _parallel_marking_threads at it's
2384 // value originally calculated in the ConcurrentMark
2385 // constructor and pass values of the active workers
2386 // through the gang in the task.
2388 CMRemarkTask remarkTask(this, active_workers);
2389 g1h->set_par_threads(active_workers);
2390 g1h->workers()->run_task(&remarkTask);
2391 g1h->set_par_threads(0);
2392 } else {
2393 G1CollectedHeap::StrongRootsScope srs(g1h);
2394 // this is remark, so we'll use up all available threads
2395 uint active_workers = 1;
2396 set_phase(active_workers, false /* concurrent */);
2398 CMRemarkTask remarkTask(this, active_workers);
2399 // We will start all available threads, even if we decide that the
2400 // active_workers will be fewer. The extra ones will just bail out
2401 // immediately.
2402 remarkTask.work(0);
2403 }
2404 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
2405 guarantee(satb_mq_set.completed_buffers_num() == 0, "invariant");
2407 print_stats();
2409 #if VERIFY_OBJS_PROCESSED
2410 if (_scan_obj_cl.objs_processed != ThreadLocalObjQueue::objs_enqueued) {
2411 gclog_or_tty->print_cr("Processed = %d, enqueued = %d.",
2412 _scan_obj_cl.objs_processed,
2413 ThreadLocalObjQueue::objs_enqueued);
2414 guarantee(_scan_obj_cl.objs_processed ==
2415 ThreadLocalObjQueue::objs_enqueued,
2416 "Different number of objs processed and enqueued.");
2417 }
2418 #endif
2419 }
2421 #ifndef PRODUCT
2423 class PrintReachableOopClosure: public OopClosure {
2424 private:
2425 G1CollectedHeap* _g1h;
2426 outputStream* _out;
2427 VerifyOption _vo;
2428 bool _all;
2430 public:
2431 PrintReachableOopClosure(outputStream* out,
2432 VerifyOption vo,
2433 bool all) :
2434 _g1h(G1CollectedHeap::heap()),
2435 _out(out), _vo(vo), _all(all) { }
2437 void do_oop(narrowOop* p) { do_oop_work(p); }
2438 void do_oop( oop* p) { do_oop_work(p); }
2440 template <class T> void do_oop_work(T* p) {
2441 oop obj = oopDesc::load_decode_heap_oop(p);
2442 const char* str = NULL;
2443 const char* str2 = "";
2445 if (obj == NULL) {
2446 str = "";
2447 } else if (!_g1h->is_in_g1_reserved(obj)) {
2448 str = " O";
2449 } else {
2450 HeapRegion* hr = _g1h->heap_region_containing(obj);
2451 guarantee(hr != NULL, "invariant");
2452 bool over_tams = false;
2453 bool marked = false;
2455 switch (_vo) {
2456 case VerifyOption_G1UsePrevMarking:
2457 over_tams = hr->obj_allocated_since_prev_marking(obj);
2458 marked = _g1h->isMarkedPrev(obj);
2459 break;
2460 case VerifyOption_G1UseNextMarking:
2461 over_tams = hr->obj_allocated_since_next_marking(obj);
2462 marked = _g1h->isMarkedNext(obj);
2463 break;
2464 case VerifyOption_G1UseMarkWord:
2465 marked = obj->is_gc_marked();
2466 break;
2467 default:
2468 ShouldNotReachHere();
2469 }
2471 if (over_tams) {
2472 str = " >";
2473 if (marked) {
2474 str2 = " AND MARKED";
2475 }
2476 } else if (marked) {
2477 str = " M";
2478 } else {
2479 str = " NOT";
2480 }
2481 }
2483 _out->print_cr(" "PTR_FORMAT": "PTR_FORMAT"%s%s",
2484 p, (void*) obj, str, str2);
2485 }
2486 };
2488 class PrintReachableObjectClosure : public ObjectClosure {
2489 private:
2490 G1CollectedHeap* _g1h;
2491 outputStream* _out;
2492 VerifyOption _vo;
2493 bool _all;
2494 HeapRegion* _hr;
2496 public:
2497 PrintReachableObjectClosure(outputStream* out,
2498 VerifyOption vo,
2499 bool all,
2500 HeapRegion* hr) :
2501 _g1h(G1CollectedHeap::heap()),
2502 _out(out), _vo(vo), _all(all), _hr(hr) { }
2504 void do_object(oop o) {
2505 bool over_tams = false;
2506 bool marked = false;
2508 switch (_vo) {
2509 case VerifyOption_G1UsePrevMarking:
2510 over_tams = _hr->obj_allocated_since_prev_marking(o);
2511 marked = _g1h->isMarkedPrev(o);
2512 break;
2513 case VerifyOption_G1UseNextMarking:
2514 over_tams = _hr->obj_allocated_since_next_marking(o);
2515 marked = _g1h->isMarkedNext(o);
2516 break;
2517 case VerifyOption_G1UseMarkWord:
2518 marked = o->is_gc_marked();
2519 break;
2520 default:
2521 ShouldNotReachHere();
2522 }
2523 bool print_it = _all || over_tams || marked;
2525 if (print_it) {
2526 _out->print_cr(" "PTR_FORMAT"%s",
2527 o, (over_tams) ? " >" : (marked) ? " M" : "");
2528 PrintReachableOopClosure oopCl(_out, _vo, _all);
2529 o->oop_iterate(&oopCl);
2530 }
2531 }
2532 };
2534 class PrintReachableRegionClosure : public HeapRegionClosure {
2535 private:
2536 outputStream* _out;
2537 VerifyOption _vo;
2538 bool _all;
2540 public:
2541 bool doHeapRegion(HeapRegion* hr) {
2542 HeapWord* b = hr->bottom();
2543 HeapWord* e = hr->end();
2544 HeapWord* t = hr->top();
2545 HeapWord* p = NULL;
2547 switch (_vo) {
2548 case VerifyOption_G1UsePrevMarking:
2549 p = hr->prev_top_at_mark_start();
2550 break;
2551 case VerifyOption_G1UseNextMarking:
2552 p = hr->next_top_at_mark_start();
2553 break;
2554 case VerifyOption_G1UseMarkWord:
2555 // When we are verifying marking using the mark word
2556 // TAMS has no relevance.
2557 assert(p == NULL, "post-condition");
2558 break;
2559 default:
2560 ShouldNotReachHere();
2561 }
2562 _out->print_cr("** ["PTR_FORMAT", "PTR_FORMAT"] top: "PTR_FORMAT" "
2563 "TAMS: "PTR_FORMAT, b, e, t, p);
2564 _out->cr();
2566 HeapWord* from = b;
2567 HeapWord* to = t;
2569 if (to > from) {
2570 _out->print_cr("Objects in ["PTR_FORMAT", "PTR_FORMAT"]", from, to);
2571 _out->cr();
2572 PrintReachableObjectClosure ocl(_out, _vo, _all, hr);
2573 hr->object_iterate_mem_careful(MemRegion(from, to), &ocl);
2574 _out->cr();
2575 }
2577 return false;
2578 }
2580 PrintReachableRegionClosure(outputStream* out,
2581 VerifyOption vo,
2582 bool all) :
2583 _out(out), _vo(vo), _all(all) { }
2584 };
2586 static const char* verify_option_to_tams(VerifyOption vo) {
2587 switch (vo) {
2588 case VerifyOption_G1UsePrevMarking:
2589 return "PTAMS";
2590 case VerifyOption_G1UseNextMarking:
2591 return "NTAMS";
2592 default:
2593 return "NONE";
2594 }
2595 }
2597 void ConcurrentMark::print_reachable(const char* str,
2598 VerifyOption vo,
2599 bool all) {
2600 gclog_or_tty->cr();
2601 gclog_or_tty->print_cr("== Doing heap dump... ");
2603 if (G1PrintReachableBaseFile == NULL) {
2604 gclog_or_tty->print_cr(" #### error: no base file defined");
2605 return;
2606 }
2608 if (strlen(G1PrintReachableBaseFile) + 1 + strlen(str) >
2609 (JVM_MAXPATHLEN - 1)) {
2610 gclog_or_tty->print_cr(" #### error: file name too long");
2611 return;
2612 }
2614 char file_name[JVM_MAXPATHLEN];
2615 sprintf(file_name, "%s.%s", G1PrintReachableBaseFile, str);
2616 gclog_or_tty->print_cr(" dumping to file %s", file_name);
2618 fileStream fout(file_name);
2619 if (!fout.is_open()) {
2620 gclog_or_tty->print_cr(" #### error: could not open file");
2621 return;
2622 }
2624 outputStream* out = &fout;
2625 out->print_cr("-- USING %s", verify_option_to_tams(vo));
2626 out->cr();
2628 out->print_cr("--- ITERATING OVER REGIONS");
2629 out->cr();
2630 PrintReachableRegionClosure rcl(out, vo, all);
2631 _g1h->heap_region_iterate(&rcl);
2632 out->cr();
2634 gclog_or_tty->print_cr(" done");
2635 gclog_or_tty->flush();
2636 }
2638 #endif // PRODUCT
2640 void ConcurrentMark::clearRangePrevBitmap(MemRegion mr) {
2641 // Note we are overriding the read-only view of the prev map here, via
2642 // the cast.
2643 ((CMBitMap*)_prevMarkBitMap)->clearRange(mr);
2644 }
2646 void ConcurrentMark::clearRangeNextBitmap(MemRegion mr) {
2647 _nextMarkBitMap->clearRange(mr);
2648 }
2650 void ConcurrentMark::clearRangeBothBitmaps(MemRegion mr) {
2651 clearRangePrevBitmap(mr);
2652 clearRangeNextBitmap(mr);
2653 }
2655 HeapRegion*
2656 ConcurrentMark::claim_region(int task_num) {
2657 // "checkpoint" the finger
2658 HeapWord* finger = _finger;
2660 // _heap_end will not change underneath our feet; it only changes at
2661 // yield points.
2662 while (finger < _heap_end) {
2663 assert(_g1h->is_in_g1_reserved(finger), "invariant");
2665 // Note on how this code handles humongous regions. In the
2666 // normal case the finger will reach the start of a "starts
2667 // humongous" (SH) region. Its end will either be the end of the
2668 // last "continues humongous" (CH) region in the sequence, or the
2669 // standard end of the SH region (if the SH is the only region in
2670 // the sequence). That way claim_region() will skip over the CH
2671 // regions. However, there is a subtle race between a CM thread
2672 // executing this method and a mutator thread doing a humongous
2673 // object allocation. The two are not mutually exclusive as the CM
2674 // thread does not need to hold the Heap_lock when it gets
2675 // here. So there is a chance that claim_region() will come across
2676 // a free region that's in the progress of becoming a SH or a CH
2677 // region. In the former case, it will either
2678 // a) Miss the update to the region's end, in which case it will
2679 // visit every subsequent CH region, will find their bitmaps
2680 // empty, and do nothing, or
2681 // b) Will observe the update of the region's end (in which case
2682 // it will skip the subsequent CH regions).
2683 // If it comes across a region that suddenly becomes CH, the
2684 // scenario will be similar to b). So, the race between
2685 // claim_region() and a humongous object allocation might force us
2686 // to do a bit of unnecessary work (due to some unnecessary bitmap
2687 // iterations) but it should not introduce and correctness issues.
2688 HeapRegion* curr_region = _g1h->heap_region_containing_raw(finger);
2689 HeapWord* bottom = curr_region->bottom();
2690 HeapWord* end = curr_region->end();
2691 HeapWord* limit = curr_region->next_top_at_mark_start();
2693 if (verbose_low()) {
2694 gclog_or_tty->print_cr("[%d] curr_region = "PTR_FORMAT" "
2695 "["PTR_FORMAT", "PTR_FORMAT"), "
2696 "limit = "PTR_FORMAT,
2697 task_num, curr_region, bottom, end, limit);
2698 }
2700 // Is the gap between reading the finger and doing the CAS too long?
2701 HeapWord* res = (HeapWord*) Atomic::cmpxchg_ptr(end, &_finger, finger);
2702 if (res == finger) {
2703 // we succeeded
2705 // notice that _finger == end cannot be guaranteed here since,
2706 // someone else might have moved the finger even further
2707 assert(_finger >= end, "the finger should have moved forward");
2709 if (verbose_low()) {
2710 gclog_or_tty->print_cr("[%d] we were successful with region = "
2711 PTR_FORMAT, task_num, curr_region);
2712 }
2714 if (limit > bottom) {
2715 if (verbose_low()) {
2716 gclog_or_tty->print_cr("[%d] region "PTR_FORMAT" is not empty, "
2717 "returning it ", task_num, curr_region);
2718 }
2719 return curr_region;
2720 } else {
2721 assert(limit == bottom,
2722 "the region limit should be at bottom");
2723 if (verbose_low()) {
2724 gclog_or_tty->print_cr("[%d] region "PTR_FORMAT" is empty, "
2725 "returning NULL", task_num, curr_region);
2726 }
2727 // we return NULL and the caller should try calling
2728 // claim_region() again.
2729 return NULL;
2730 }
2731 } else {
2732 assert(_finger > finger, "the finger should have moved forward");
2733 if (verbose_low()) {
2734 gclog_or_tty->print_cr("[%d] somebody else moved the finger, "
2735 "global finger = "PTR_FORMAT", "
2736 "our finger = "PTR_FORMAT,
2737 task_num, _finger, finger);
2738 }
2740 // read it again
2741 finger = _finger;
2742 }
2743 }
2745 return NULL;
2746 }
2748 #ifndef PRODUCT
2749 enum VerifyNoCSetOopsPhase {
2750 VerifyNoCSetOopsStack,
2751 VerifyNoCSetOopsQueues,
2752 VerifyNoCSetOopsSATBCompleted,
2753 VerifyNoCSetOopsSATBThread
2754 };
2756 class VerifyNoCSetOopsClosure : public OopClosure, public ObjectClosure {
2757 private:
2758 G1CollectedHeap* _g1h;
2759 VerifyNoCSetOopsPhase _phase;
2760 int _info;
2762 const char* phase_str() {
2763 switch (_phase) {
2764 case VerifyNoCSetOopsStack: return "Stack";
2765 case VerifyNoCSetOopsQueues: return "Queue";
2766 case VerifyNoCSetOopsSATBCompleted: return "Completed SATB Buffers";
2767 case VerifyNoCSetOopsSATBThread: return "Thread SATB Buffers";
2768 default: ShouldNotReachHere();
2769 }
2770 return NULL;
2771 }
2773 void do_object_work(oop obj) {
2774 guarantee(!_g1h->obj_in_cs(obj),
2775 err_msg("obj: "PTR_FORMAT" in CSet, phase: %s, info: %d",
2776 (void*) obj, phase_str(), _info));
2777 }
2779 public:
2780 VerifyNoCSetOopsClosure() : _g1h(G1CollectedHeap::heap()) { }
2782 void set_phase(VerifyNoCSetOopsPhase phase, int info = -1) {
2783 _phase = phase;
2784 _info = info;
2785 }
2787 virtual void do_oop(oop* p) {
2788 oop obj = oopDesc::load_decode_heap_oop(p);
2789 do_object_work(obj);
2790 }
2792 virtual void do_oop(narrowOop* p) {
2793 // We should not come across narrow oops while scanning marking
2794 // stacks and SATB buffers.
2795 ShouldNotReachHere();
2796 }
2798 virtual void do_object(oop obj) {
2799 do_object_work(obj);
2800 }
2801 };
2803 void ConcurrentMark::verify_no_cset_oops(bool verify_stacks,
2804 bool verify_enqueued_buffers,
2805 bool verify_thread_buffers,
2806 bool verify_fingers) {
2807 assert(SafepointSynchronize::is_at_safepoint(), "should be at a safepoint");
2808 if (!G1CollectedHeap::heap()->mark_in_progress()) {
2809 return;
2810 }
2812 VerifyNoCSetOopsClosure cl;
2814 if (verify_stacks) {
2815 // Verify entries on the global mark stack
2816 cl.set_phase(VerifyNoCSetOopsStack);
2817 _markStack.oops_do(&cl);
2819 // Verify entries on the task queues
2820 for (int i = 0; i < (int) _max_task_num; i += 1) {
2821 cl.set_phase(VerifyNoCSetOopsQueues, i);
2822 OopTaskQueue* queue = _task_queues->queue(i);
2823 queue->oops_do(&cl);
2824 }
2825 }
2827 SATBMarkQueueSet& satb_qs = JavaThread::satb_mark_queue_set();
2829 // Verify entries on the enqueued SATB buffers
2830 if (verify_enqueued_buffers) {
2831 cl.set_phase(VerifyNoCSetOopsSATBCompleted);
2832 satb_qs.iterate_completed_buffers_read_only(&cl);
2833 }
2835 // Verify entries on the per-thread SATB buffers
2836 if (verify_thread_buffers) {
2837 cl.set_phase(VerifyNoCSetOopsSATBThread);
2838 satb_qs.iterate_thread_buffers_read_only(&cl);
2839 }
2841 if (verify_fingers) {
2842 // Verify the global finger
2843 HeapWord* global_finger = finger();
2844 if (global_finger != NULL && global_finger < _heap_end) {
2845 // The global finger always points to a heap region boundary. We
2846 // use heap_region_containing_raw() to get the containing region
2847 // given that the global finger could be pointing to a free region
2848 // which subsequently becomes continues humongous. If that
2849 // happens, heap_region_containing() will return the bottom of the
2850 // corresponding starts humongous region and the check below will
2851 // not hold any more.
2852 HeapRegion* global_hr = _g1h->heap_region_containing_raw(global_finger);
2853 guarantee(global_finger == global_hr->bottom(),
2854 err_msg("global finger: "PTR_FORMAT" region: "HR_FORMAT,
2855 global_finger, HR_FORMAT_PARAMS(global_hr)));
2856 }
2858 // Verify the task fingers
2859 assert(parallel_marking_threads() <= _max_task_num, "sanity");
2860 for (int i = 0; i < (int) parallel_marking_threads(); i += 1) {
2861 CMTask* task = _tasks[i];
2862 HeapWord* task_finger = task->finger();
2863 if (task_finger != NULL && task_finger < _heap_end) {
2864 // See above note on the global finger verification.
2865 HeapRegion* task_hr = _g1h->heap_region_containing_raw(task_finger);
2866 guarantee(task_finger == task_hr->bottom() ||
2867 !task_hr->in_collection_set(),
2868 err_msg("task finger: "PTR_FORMAT" region: "HR_FORMAT,
2869 task_finger, HR_FORMAT_PARAMS(task_hr)));
2870 }
2871 }
2872 }
2873 }
2874 #endif // PRODUCT
2876 void ConcurrentMark::clear_marking_state(bool clear_overflow) {
2877 _markStack.setEmpty();
2878 _markStack.clear_overflow();
2879 if (clear_overflow) {
2880 clear_has_overflown();
2881 } else {
2882 assert(has_overflown(), "pre-condition");
2883 }
2884 _finger = _heap_start;
2886 for (int i = 0; i < (int)_max_task_num; ++i) {
2887 OopTaskQueue* queue = _task_queues->queue(i);
2888 queue->set_empty();
2889 }
2890 }
2892 // Aggregate the counting data that was constructed concurrently
2893 // with marking.
2894 class AggregateCountDataHRClosure: public HeapRegionClosure {
2895 ConcurrentMark* _cm;
2896 BitMap* _cm_card_bm;
2897 size_t _max_task_num;
2899 public:
2900 AggregateCountDataHRClosure(ConcurrentMark *cm,
2901 BitMap* cm_card_bm,
2902 size_t max_task_num) :
2903 _cm(cm), _cm_card_bm(cm_card_bm),
2904 _max_task_num(max_task_num) { }
2906 bool is_card_aligned(HeapWord* p) {
2907 return ((uintptr_t(p) & (CardTableModRefBS::card_size - 1)) == 0);
2908 }
2910 bool doHeapRegion(HeapRegion* hr) {
2911 if (hr->continuesHumongous()) {
2912 // We will ignore these here and process them when their
2913 // associated "starts humongous" region is processed.
2914 // Note that we cannot rely on their associated
2915 // "starts humongous" region to have their bit set to 1
2916 // since, due to the region chunking in the parallel region
2917 // iteration, a "continues humongous" region might be visited
2918 // before its associated "starts humongous".
2919 return false;
2920 }
2922 HeapWord* start = hr->bottom();
2923 HeapWord* limit = hr->next_top_at_mark_start();
2924 HeapWord* end = hr->end();
2926 assert(start <= limit && limit <= hr->top() && hr->top() <= hr->end(),
2927 err_msg("Preconditions not met - "
2928 "start: "PTR_FORMAT", limit: "PTR_FORMAT", "
2929 "top: "PTR_FORMAT", end: "PTR_FORMAT,
2930 start, limit, hr->top(), hr->end()));
2932 assert(hr->next_marked_bytes() == 0, "Precondition");
2934 if (start == limit) {
2935 // NTAMS of this region has not been set so nothing to do.
2936 return false;
2937 }
2939 assert(is_card_aligned(start), "sanity");
2940 assert(is_card_aligned(end), "sanity");
2942 BitMap::idx_t start_idx = _cm->card_bitmap_index_for(start);
2943 BitMap::idx_t limit_idx = _cm->card_bitmap_index_for(limit);
2944 BitMap::idx_t end_idx = _cm->card_bitmap_index_for(end);
2946 // If ntams is not card aligned then we bump the index for
2947 // limit so that we get the card spanning ntams.
2948 if (!is_card_aligned(limit)) {
2949 limit_idx += 1;
2950 }
2952 assert(limit_idx <= end_idx, "or else use atomics");
2954 // Aggregate the "stripe" in the count data associated with hr.
2955 uint hrs_index = hr->hrs_index();
2956 size_t marked_bytes = 0;
2958 for (int i = 0; (size_t)i < _max_task_num; i += 1) {
2959 size_t* marked_bytes_array = _cm->count_marked_bytes_array_for(i);
2960 BitMap* task_card_bm = _cm->count_card_bitmap_for(i);
2962 // Fetch the marked_bytes in this region for task i and
2963 // add it to the running total for this region.
2964 marked_bytes += marked_bytes_array[hrs_index];
2966 // Now union the bitmaps[0,max_task_num)[start_idx..limit_idx)
2967 // into the global card bitmap.
2968 BitMap::idx_t scan_idx = task_card_bm->get_next_one_offset(start_idx, limit_idx);
2970 while (scan_idx < limit_idx) {
2971 assert(task_card_bm->at(scan_idx) == true, "should be");
2972 _cm_card_bm->set_bit(scan_idx);
2973 assert(_cm_card_bm->at(scan_idx) == true, "should be");
2975 // BitMap::get_next_one_offset() can handle the case when
2976 // its left_offset parameter is greater than its right_offset
2977 // parameter. If does, however, have an early exit if
2978 // left_offset == right_offset. So let's limit the value
2979 // passed in for left offset here.
2980 BitMap::idx_t next_idx = MIN2(scan_idx + 1, limit_idx);
2981 scan_idx = task_card_bm->get_next_one_offset(next_idx, limit_idx);
2982 }
2983 }
2985 // Update the marked bytes for this region.
2986 hr->add_to_marked_bytes(marked_bytes);
2988 // Next heap region
2989 return false;
2990 }
2991 };
2993 class G1AggregateCountDataTask: public AbstractGangTask {
2994 protected:
2995 G1CollectedHeap* _g1h;
2996 ConcurrentMark* _cm;
2997 BitMap* _cm_card_bm;
2998 size_t _max_task_num;
2999 int _active_workers;
3001 public:
3002 G1AggregateCountDataTask(G1CollectedHeap* g1h,
3003 ConcurrentMark* cm,
3004 BitMap* cm_card_bm,
3005 size_t max_task_num,
3006 int n_workers) :
3007 AbstractGangTask("Count Aggregation"),
3008 _g1h(g1h), _cm(cm), _cm_card_bm(cm_card_bm),
3009 _max_task_num(max_task_num),
3010 _active_workers(n_workers) { }
3012 void work(uint worker_id) {
3013 AggregateCountDataHRClosure cl(_cm, _cm_card_bm, _max_task_num);
3015 if (G1CollectedHeap::use_parallel_gc_threads()) {
3016 _g1h->heap_region_par_iterate_chunked(&cl, worker_id,
3017 _active_workers,
3018 HeapRegion::AggregateCountClaimValue);
3019 } else {
3020 _g1h->heap_region_iterate(&cl);
3021 }
3022 }
3023 };
3026 void ConcurrentMark::aggregate_count_data() {
3027 int n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
3028 _g1h->workers()->active_workers() :
3029 1);
3031 G1AggregateCountDataTask g1_par_agg_task(_g1h, this, &_card_bm,
3032 _max_task_num, n_workers);
3034 if (G1CollectedHeap::use_parallel_gc_threads()) {
3035 assert(_g1h->check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3036 "sanity check");
3037 _g1h->set_par_threads(n_workers);
3038 _g1h->workers()->run_task(&g1_par_agg_task);
3039 _g1h->set_par_threads(0);
3041 assert(_g1h->check_heap_region_claim_values(HeapRegion::AggregateCountClaimValue),
3042 "sanity check");
3043 _g1h->reset_heap_region_claim_values();
3044 } else {
3045 g1_par_agg_task.work(0);
3046 }
3047 }
3049 // Clear the per-worker arrays used to store the per-region counting data
3050 void ConcurrentMark::clear_all_count_data() {
3051 // Clear the global card bitmap - it will be filled during
3052 // liveness count aggregation (during remark) and the
3053 // final counting task.
3054 _card_bm.clear();
3056 // Clear the global region bitmap - it will be filled as part
3057 // of the final counting task.
3058 _region_bm.clear();
3060 uint max_regions = _g1h->max_regions();
3061 assert(_max_task_num != 0, "unitialized");
3063 for (int i = 0; (size_t) i < _max_task_num; i += 1) {
3064 BitMap* task_card_bm = count_card_bitmap_for(i);
3065 size_t* marked_bytes_array = count_marked_bytes_array_for(i);
3067 assert(task_card_bm->size() == _card_bm.size(), "size mismatch");
3068 assert(marked_bytes_array != NULL, "uninitialized");
3070 memset(marked_bytes_array, 0, (size_t) max_regions * sizeof(size_t));
3071 task_card_bm->clear();
3072 }
3073 }
3075 void ConcurrentMark::print_stats() {
3076 if (verbose_stats()) {
3077 gclog_or_tty->print_cr("---------------------------------------------------------------------");
3078 for (size_t i = 0; i < _active_tasks; ++i) {
3079 _tasks[i]->print_stats();
3080 gclog_or_tty->print_cr("---------------------------------------------------------------------");
3081 }
3082 }
3083 }
3085 // abandon current marking iteration due to a Full GC
3086 void ConcurrentMark::abort() {
3087 // Clear all marks to force marking thread to do nothing
3088 _nextMarkBitMap->clearAll();
3089 // Clear the liveness counting data
3090 clear_all_count_data();
3091 // Empty mark stack
3092 clear_marking_state();
3093 for (int i = 0; i < (int)_max_task_num; ++i) {
3094 _tasks[i]->clear_region_fields();
3095 }
3096 _has_aborted = true;
3098 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
3099 satb_mq_set.abandon_partial_marking();
3100 // This can be called either during or outside marking, we'll read
3101 // the expected_active value from the SATB queue set.
3102 satb_mq_set.set_active_all_threads(
3103 false, /* new active value */
3104 satb_mq_set.is_active() /* expected_active */);
3105 }
3107 static void print_ms_time_info(const char* prefix, const char* name,
3108 NumberSeq& ns) {
3109 gclog_or_tty->print_cr("%s%5d %12s: total time = %8.2f s (avg = %8.2f ms).",
3110 prefix, ns.num(), name, ns.sum()/1000.0, ns.avg());
3111 if (ns.num() > 0) {
3112 gclog_or_tty->print_cr("%s [std. dev = %8.2f ms, max = %8.2f ms]",
3113 prefix, ns.sd(), ns.maximum());
3114 }
3115 }
3117 void ConcurrentMark::print_summary_info() {
3118 gclog_or_tty->print_cr(" Concurrent marking:");
3119 print_ms_time_info(" ", "init marks", _init_times);
3120 print_ms_time_info(" ", "remarks", _remark_times);
3121 {
3122 print_ms_time_info(" ", "final marks", _remark_mark_times);
3123 print_ms_time_info(" ", "weak refs", _remark_weak_ref_times);
3125 }
3126 print_ms_time_info(" ", "cleanups", _cleanup_times);
3127 gclog_or_tty->print_cr(" Final counting total time = %8.2f s (avg = %8.2f ms).",
3128 _total_counting_time,
3129 (_cleanup_times.num() > 0 ? _total_counting_time * 1000.0 /
3130 (double)_cleanup_times.num()
3131 : 0.0));
3132 if (G1ScrubRemSets) {
3133 gclog_or_tty->print_cr(" RS scrub total time = %8.2f s (avg = %8.2f ms).",
3134 _total_rs_scrub_time,
3135 (_cleanup_times.num() > 0 ? _total_rs_scrub_time * 1000.0 /
3136 (double)_cleanup_times.num()
3137 : 0.0));
3138 }
3139 gclog_or_tty->print_cr(" Total stop_world time = %8.2f s.",
3140 (_init_times.sum() + _remark_times.sum() +
3141 _cleanup_times.sum())/1000.0);
3142 gclog_or_tty->print_cr(" Total concurrent time = %8.2f s "
3143 "(%8.2f s marking).",
3144 cmThread()->vtime_accum(),
3145 cmThread()->vtime_mark_accum());
3146 }
3148 void ConcurrentMark::print_worker_threads_on(outputStream* st) const {
3149 _parallel_workers->print_worker_threads_on(st);
3150 }
3152 // We take a break if someone is trying to stop the world.
3153 bool ConcurrentMark::do_yield_check(uint worker_id) {
3154 if (should_yield()) {
3155 if (worker_id == 0) {
3156 _g1h->g1_policy()->record_concurrent_pause();
3157 }
3158 cmThread()->yield();
3159 if (worker_id == 0) {
3160 _g1h->g1_policy()->record_concurrent_pause_end();
3161 }
3162 return true;
3163 } else {
3164 return false;
3165 }
3166 }
3168 bool ConcurrentMark::should_yield() {
3169 return cmThread()->should_yield();
3170 }
3172 bool ConcurrentMark::containing_card_is_marked(void* p) {
3173 size_t offset = pointer_delta(p, _g1h->reserved_region().start(), 1);
3174 return _card_bm.at(offset >> CardTableModRefBS::card_shift);
3175 }
3177 bool ConcurrentMark::containing_cards_are_marked(void* start,
3178 void* last) {
3179 return containing_card_is_marked(start) &&
3180 containing_card_is_marked(last);
3181 }
3183 #ifndef PRODUCT
3184 // for debugging purposes
3185 void ConcurrentMark::print_finger() {
3186 gclog_or_tty->print_cr("heap ["PTR_FORMAT", "PTR_FORMAT"), global finger = "PTR_FORMAT,
3187 _heap_start, _heap_end, _finger);
3188 for (int i = 0; i < (int) _max_task_num; ++i) {
3189 gclog_or_tty->print(" %d: "PTR_FORMAT, i, _tasks[i]->finger());
3190 }
3191 gclog_or_tty->print_cr("");
3192 }
3193 #endif
3195 void CMTask::scan_object(oop obj) {
3196 assert(_nextMarkBitMap->isMarked((HeapWord*) obj), "invariant");
3198 if (_cm->verbose_high()) {
3199 gclog_or_tty->print_cr("[%d] we're scanning object "PTR_FORMAT,
3200 _task_id, (void*) obj);
3201 }
3203 size_t obj_size = obj->size();
3204 _words_scanned += obj_size;
3206 obj->oop_iterate(_cm_oop_closure);
3207 statsOnly( ++_objs_scanned );
3208 check_limits();
3209 }
3211 // Closure for iteration over bitmaps
3212 class CMBitMapClosure : public BitMapClosure {
3213 private:
3214 // the bitmap that is being iterated over
3215 CMBitMap* _nextMarkBitMap;
3216 ConcurrentMark* _cm;
3217 CMTask* _task;
3219 public:
3220 CMBitMapClosure(CMTask *task, ConcurrentMark* cm, CMBitMap* nextMarkBitMap) :
3221 _task(task), _cm(cm), _nextMarkBitMap(nextMarkBitMap) { }
3223 bool do_bit(size_t offset) {
3224 HeapWord* addr = _nextMarkBitMap->offsetToHeapWord(offset);
3225 assert(_nextMarkBitMap->isMarked(addr), "invariant");
3226 assert( addr < _cm->finger(), "invariant");
3228 statsOnly( _task->increase_objs_found_on_bitmap() );
3229 assert(addr >= _task->finger(), "invariant");
3231 // We move that task's local finger along.
3232 _task->move_finger_to(addr);
3234 _task->scan_object(oop(addr));
3235 // we only partially drain the local queue and global stack
3236 _task->drain_local_queue(true);
3237 _task->drain_global_stack(true);
3239 // if the has_aborted flag has been raised, we need to bail out of
3240 // the iteration
3241 return !_task->has_aborted();
3242 }
3243 };
3245 // Closure for iterating over objects, currently only used for
3246 // processing SATB buffers.
3247 class CMObjectClosure : public ObjectClosure {
3248 private:
3249 CMTask* _task;
3251 public:
3252 void do_object(oop obj) {
3253 _task->deal_with_reference(obj);
3254 }
3256 CMObjectClosure(CMTask* task) : _task(task) { }
3257 };
3259 G1CMOopClosure::G1CMOopClosure(G1CollectedHeap* g1h,
3260 ConcurrentMark* cm,
3261 CMTask* task)
3262 : _g1h(g1h), _cm(cm), _task(task) {
3263 assert(_ref_processor == NULL, "should be initialized to NULL");
3265 if (G1UseConcMarkReferenceProcessing) {
3266 _ref_processor = g1h->ref_processor_cm();
3267 assert(_ref_processor != NULL, "should not be NULL");
3268 }
3269 }
3271 void CMTask::setup_for_region(HeapRegion* hr) {
3272 // Separated the asserts so that we know which one fires.
3273 assert(hr != NULL,
3274 "claim_region() should have filtered out continues humongous regions");
3275 assert(!hr->continuesHumongous(),
3276 "claim_region() should have filtered out continues humongous regions");
3278 if (_cm->verbose_low()) {
3279 gclog_or_tty->print_cr("[%d] setting up for region "PTR_FORMAT,
3280 _task_id, hr);
3281 }
3283 _curr_region = hr;
3284 _finger = hr->bottom();
3285 update_region_limit();
3286 }
3288 void CMTask::update_region_limit() {
3289 HeapRegion* hr = _curr_region;
3290 HeapWord* bottom = hr->bottom();
3291 HeapWord* limit = hr->next_top_at_mark_start();
3293 if (limit == bottom) {
3294 if (_cm->verbose_low()) {
3295 gclog_or_tty->print_cr("[%d] found an empty region "
3296 "["PTR_FORMAT", "PTR_FORMAT")",
3297 _task_id, bottom, limit);
3298 }
3299 // The region was collected underneath our feet.
3300 // We set the finger to bottom to ensure that the bitmap
3301 // iteration that will follow this will not do anything.
3302 // (this is not a condition that holds when we set the region up,
3303 // as the region is not supposed to be empty in the first place)
3304 _finger = bottom;
3305 } else if (limit >= _region_limit) {
3306 assert(limit >= _finger, "peace of mind");
3307 } else {
3308 assert(limit < _region_limit, "only way to get here");
3309 // This can happen under some pretty unusual circumstances. An
3310 // evacuation pause empties the region underneath our feet (NTAMS
3311 // at bottom). We then do some allocation in the region (NTAMS
3312 // stays at bottom), followed by the region being used as a GC
3313 // alloc region (NTAMS will move to top() and the objects
3314 // originally below it will be grayed). All objects now marked in
3315 // the region are explicitly grayed, if below the global finger,
3316 // and we do not need in fact to scan anything else. So, we simply
3317 // set _finger to be limit to ensure that the bitmap iteration
3318 // doesn't do anything.
3319 _finger = limit;
3320 }
3322 _region_limit = limit;
3323 }
3325 void CMTask::giveup_current_region() {
3326 assert(_curr_region != NULL, "invariant");
3327 if (_cm->verbose_low()) {
3328 gclog_or_tty->print_cr("[%d] giving up region "PTR_FORMAT,
3329 _task_id, _curr_region);
3330 }
3331 clear_region_fields();
3332 }
3334 void CMTask::clear_region_fields() {
3335 // Values for these three fields that indicate that we're not
3336 // holding on to a region.
3337 _curr_region = NULL;
3338 _finger = NULL;
3339 _region_limit = NULL;
3340 }
3342 void CMTask::set_cm_oop_closure(G1CMOopClosure* cm_oop_closure) {
3343 if (cm_oop_closure == NULL) {
3344 assert(_cm_oop_closure != NULL, "invariant");
3345 } else {
3346 assert(_cm_oop_closure == NULL, "invariant");
3347 }
3348 _cm_oop_closure = cm_oop_closure;
3349 }
3351 void CMTask::reset(CMBitMap* nextMarkBitMap) {
3352 guarantee(nextMarkBitMap != NULL, "invariant");
3354 if (_cm->verbose_low()) {
3355 gclog_or_tty->print_cr("[%d] resetting", _task_id);
3356 }
3358 _nextMarkBitMap = nextMarkBitMap;
3359 clear_region_fields();
3361 _calls = 0;
3362 _elapsed_time_ms = 0.0;
3363 _termination_time_ms = 0.0;
3364 _termination_start_time_ms = 0.0;
3366 #if _MARKING_STATS_
3367 _local_pushes = 0;
3368 _local_pops = 0;
3369 _local_max_size = 0;
3370 _objs_scanned = 0;
3371 _global_pushes = 0;
3372 _global_pops = 0;
3373 _global_max_size = 0;
3374 _global_transfers_to = 0;
3375 _global_transfers_from = 0;
3376 _regions_claimed = 0;
3377 _objs_found_on_bitmap = 0;
3378 _satb_buffers_processed = 0;
3379 _steal_attempts = 0;
3380 _steals = 0;
3381 _aborted = 0;
3382 _aborted_overflow = 0;
3383 _aborted_cm_aborted = 0;
3384 _aborted_yield = 0;
3385 _aborted_timed_out = 0;
3386 _aborted_satb = 0;
3387 _aborted_termination = 0;
3388 #endif // _MARKING_STATS_
3389 }
3391 bool CMTask::should_exit_termination() {
3392 regular_clock_call();
3393 // This is called when we are in the termination protocol. We should
3394 // quit if, for some reason, this task wants to abort or the global
3395 // stack is not empty (this means that we can get work from it).
3396 return !_cm->mark_stack_empty() || has_aborted();
3397 }
3399 void CMTask::reached_limit() {
3400 assert(_words_scanned >= _words_scanned_limit ||
3401 _refs_reached >= _refs_reached_limit ,
3402 "shouldn't have been called otherwise");
3403 regular_clock_call();
3404 }
3406 void CMTask::regular_clock_call() {
3407 if (has_aborted()) return;
3409 // First, we need to recalculate the words scanned and refs reached
3410 // limits for the next clock call.
3411 recalculate_limits();
3413 // During the regular clock call we do the following
3415 // (1) If an overflow has been flagged, then we abort.
3416 if (_cm->has_overflown()) {
3417 set_has_aborted();
3418 return;
3419 }
3421 // If we are not concurrent (i.e. we're doing remark) we don't need
3422 // to check anything else. The other steps are only needed during
3423 // the concurrent marking phase.
3424 if (!concurrent()) return;
3426 // (2) If marking has been aborted for Full GC, then we also abort.
3427 if (_cm->has_aborted()) {
3428 set_has_aborted();
3429 statsOnly( ++_aborted_cm_aborted );
3430 return;
3431 }
3433 double curr_time_ms = os::elapsedVTime() * 1000.0;
3435 // (3) If marking stats are enabled, then we update the step history.
3436 #if _MARKING_STATS_
3437 if (_words_scanned >= _words_scanned_limit) {
3438 ++_clock_due_to_scanning;
3439 }
3440 if (_refs_reached >= _refs_reached_limit) {
3441 ++_clock_due_to_marking;
3442 }
3444 double last_interval_ms = curr_time_ms - _interval_start_time_ms;
3445 _interval_start_time_ms = curr_time_ms;
3446 _all_clock_intervals_ms.add(last_interval_ms);
3448 if (_cm->verbose_medium()) {
3449 gclog_or_tty->print_cr("[%d] regular clock, interval = %1.2lfms, "
3450 "scanned = %d%s, refs reached = %d%s",
3451 _task_id, last_interval_ms,
3452 _words_scanned,
3453 (_words_scanned >= _words_scanned_limit) ? " (*)" : "",
3454 _refs_reached,
3455 (_refs_reached >= _refs_reached_limit) ? " (*)" : "");
3456 }
3457 #endif // _MARKING_STATS_
3459 // (4) We check whether we should yield. If we have to, then we abort.
3460 if (_cm->should_yield()) {
3461 // We should yield. To do this we abort the task. The caller is
3462 // responsible for yielding.
3463 set_has_aborted();
3464 statsOnly( ++_aborted_yield );
3465 return;
3466 }
3468 // (5) We check whether we've reached our time quota. If we have,
3469 // then we abort.
3470 double elapsed_time_ms = curr_time_ms - _start_time_ms;
3471 if (elapsed_time_ms > _time_target_ms) {
3472 set_has_aborted();
3473 _has_timed_out = true;
3474 statsOnly( ++_aborted_timed_out );
3475 return;
3476 }
3478 // (6) Finally, we check whether there are enough completed STAB
3479 // buffers available for processing. If there are, we abort.
3480 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
3481 if (!_draining_satb_buffers && satb_mq_set.process_completed_buffers()) {
3482 if (_cm->verbose_low()) {
3483 gclog_or_tty->print_cr("[%d] aborting to deal with pending SATB buffers",
3484 _task_id);
3485 }
3486 // we do need to process SATB buffers, we'll abort and restart
3487 // the marking task to do so
3488 set_has_aborted();
3489 statsOnly( ++_aborted_satb );
3490 return;
3491 }
3492 }
3494 void CMTask::recalculate_limits() {
3495 _real_words_scanned_limit = _words_scanned + words_scanned_period;
3496 _words_scanned_limit = _real_words_scanned_limit;
3498 _real_refs_reached_limit = _refs_reached + refs_reached_period;
3499 _refs_reached_limit = _real_refs_reached_limit;
3500 }
3502 void CMTask::decrease_limits() {
3503 // This is called when we believe that we're going to do an infrequent
3504 // operation which will increase the per byte scanned cost (i.e. move
3505 // entries to/from the global stack). It basically tries to decrease the
3506 // scanning limit so that the clock is called earlier.
3508 if (_cm->verbose_medium()) {
3509 gclog_or_tty->print_cr("[%d] decreasing limits", _task_id);
3510 }
3512 _words_scanned_limit = _real_words_scanned_limit -
3513 3 * words_scanned_period / 4;
3514 _refs_reached_limit = _real_refs_reached_limit -
3515 3 * refs_reached_period / 4;
3516 }
3518 void CMTask::move_entries_to_global_stack() {
3519 // local array where we'll store the entries that will be popped
3520 // from the local queue
3521 oop buffer[global_stack_transfer_size];
3523 int n = 0;
3524 oop obj;
3525 while (n < global_stack_transfer_size && _task_queue->pop_local(obj)) {
3526 buffer[n] = obj;
3527 ++n;
3528 }
3530 if (n > 0) {
3531 // we popped at least one entry from the local queue
3533 statsOnly( ++_global_transfers_to; _local_pops += n );
3535 if (!_cm->mark_stack_push(buffer, n)) {
3536 if (_cm->verbose_low()) {
3537 gclog_or_tty->print_cr("[%d] aborting due to global stack overflow",
3538 _task_id);
3539 }
3540 set_has_aborted();
3541 } else {
3542 // the transfer was successful
3544 if (_cm->verbose_medium()) {
3545 gclog_or_tty->print_cr("[%d] pushed %d entries to the global stack",
3546 _task_id, n);
3547 }
3548 statsOnly( int tmp_size = _cm->mark_stack_size();
3549 if (tmp_size > _global_max_size) {
3550 _global_max_size = tmp_size;
3551 }
3552 _global_pushes += n );
3553 }
3554 }
3556 // this operation was quite expensive, so decrease the limits
3557 decrease_limits();
3558 }
3560 void CMTask::get_entries_from_global_stack() {
3561 // local array where we'll store the entries that will be popped
3562 // from the global stack.
3563 oop buffer[global_stack_transfer_size];
3564 int n;
3565 _cm->mark_stack_pop(buffer, global_stack_transfer_size, &n);
3566 assert(n <= global_stack_transfer_size,
3567 "we should not pop more than the given limit");
3568 if (n > 0) {
3569 // yes, we did actually pop at least one entry
3571 statsOnly( ++_global_transfers_from; _global_pops += n );
3572 if (_cm->verbose_medium()) {
3573 gclog_or_tty->print_cr("[%d] popped %d entries from the global stack",
3574 _task_id, n);
3575 }
3576 for (int i = 0; i < n; ++i) {
3577 bool success = _task_queue->push(buffer[i]);
3578 // We only call this when the local queue is empty or under a
3579 // given target limit. So, we do not expect this push to fail.
3580 assert(success, "invariant");
3581 }
3583 statsOnly( int tmp_size = _task_queue->size();
3584 if (tmp_size > _local_max_size) {
3585 _local_max_size = tmp_size;
3586 }
3587 _local_pushes += n );
3588 }
3590 // this operation was quite expensive, so decrease the limits
3591 decrease_limits();
3592 }
3594 void CMTask::drain_local_queue(bool partially) {
3595 if (has_aborted()) return;
3597 // Decide what the target size is, depending whether we're going to
3598 // drain it partially (so that other tasks can steal if they run out
3599 // of things to do) or totally (at the very end).
3600 size_t target_size;
3601 if (partially) {
3602 target_size = MIN2((size_t)_task_queue->max_elems()/3, GCDrainStackTargetSize);
3603 } else {
3604 target_size = 0;
3605 }
3607 if (_task_queue->size() > target_size) {
3608 if (_cm->verbose_high()) {
3609 gclog_or_tty->print_cr("[%d] draining local queue, target size = %d",
3610 _task_id, target_size);
3611 }
3613 oop obj;
3614 bool ret = _task_queue->pop_local(obj);
3615 while (ret) {
3616 statsOnly( ++_local_pops );
3618 if (_cm->verbose_high()) {
3619 gclog_or_tty->print_cr("[%d] popped "PTR_FORMAT, _task_id,
3620 (void*) obj);
3621 }
3623 assert(_g1h->is_in_g1_reserved((HeapWord*) obj), "invariant" );
3624 assert(!_g1h->is_on_master_free_list(
3625 _g1h->heap_region_containing((HeapWord*) obj)), "invariant");
3627 scan_object(obj);
3629 if (_task_queue->size() <= target_size || has_aborted()) {
3630 ret = false;
3631 } else {
3632 ret = _task_queue->pop_local(obj);
3633 }
3634 }
3636 if (_cm->verbose_high()) {
3637 gclog_or_tty->print_cr("[%d] drained local queue, size = %d",
3638 _task_id, _task_queue->size());
3639 }
3640 }
3641 }
3643 void CMTask::drain_global_stack(bool partially) {
3644 if (has_aborted()) return;
3646 // We have a policy to drain the local queue before we attempt to
3647 // drain the global stack.
3648 assert(partially || _task_queue->size() == 0, "invariant");
3650 // Decide what the target size is, depending whether we're going to
3651 // drain it partially (so that other tasks can steal if they run out
3652 // of things to do) or totally (at the very end). Notice that,
3653 // because we move entries from the global stack in chunks or
3654 // because another task might be doing the same, we might in fact
3655 // drop below the target. But, this is not a problem.
3656 size_t target_size;
3657 if (partially) {
3658 target_size = _cm->partial_mark_stack_size_target();
3659 } else {
3660 target_size = 0;
3661 }
3663 if (_cm->mark_stack_size() > target_size) {
3664 if (_cm->verbose_low()) {
3665 gclog_or_tty->print_cr("[%d] draining global_stack, target size %d",
3666 _task_id, target_size);
3667 }
3669 while (!has_aborted() && _cm->mark_stack_size() > target_size) {
3670 get_entries_from_global_stack();
3671 drain_local_queue(partially);
3672 }
3674 if (_cm->verbose_low()) {
3675 gclog_or_tty->print_cr("[%d] drained global stack, size = %d",
3676 _task_id, _cm->mark_stack_size());
3677 }
3678 }
3679 }
3681 // SATB Queue has several assumptions on whether to call the par or
3682 // non-par versions of the methods. this is why some of the code is
3683 // replicated. We should really get rid of the single-threaded version
3684 // of the code to simplify things.
3685 void CMTask::drain_satb_buffers() {
3686 if (has_aborted()) return;
3688 // We set this so that the regular clock knows that we're in the
3689 // middle of draining buffers and doesn't set the abort flag when it
3690 // notices that SATB buffers are available for draining. It'd be
3691 // very counter productive if it did that. :-)
3692 _draining_satb_buffers = true;
3694 CMObjectClosure oc(this);
3695 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
3696 if (G1CollectedHeap::use_parallel_gc_threads()) {
3697 satb_mq_set.set_par_closure(_task_id, &oc);
3698 } else {
3699 satb_mq_set.set_closure(&oc);
3700 }
3702 // This keeps claiming and applying the closure to completed buffers
3703 // until we run out of buffers or we need to abort.
3704 if (G1CollectedHeap::use_parallel_gc_threads()) {
3705 while (!has_aborted() &&
3706 satb_mq_set.par_apply_closure_to_completed_buffer(_task_id)) {
3707 if (_cm->verbose_medium()) {
3708 gclog_or_tty->print_cr("[%d] processed an SATB buffer", _task_id);
3709 }
3710 statsOnly( ++_satb_buffers_processed );
3711 regular_clock_call();
3712 }
3713 } else {
3714 while (!has_aborted() &&
3715 satb_mq_set.apply_closure_to_completed_buffer()) {
3716 if (_cm->verbose_medium()) {
3717 gclog_or_tty->print_cr("[%d] processed an SATB buffer", _task_id);
3718 }
3719 statsOnly( ++_satb_buffers_processed );
3720 regular_clock_call();
3721 }
3722 }
3724 if (!concurrent() && !has_aborted()) {
3725 // We should only do this during remark.
3726 if (G1CollectedHeap::use_parallel_gc_threads()) {
3727 satb_mq_set.par_iterate_closure_all_threads(_task_id);
3728 } else {
3729 satb_mq_set.iterate_closure_all_threads();
3730 }
3731 }
3733 _draining_satb_buffers = false;
3735 assert(has_aborted() ||
3736 concurrent() ||
3737 satb_mq_set.completed_buffers_num() == 0, "invariant");
3739 if (G1CollectedHeap::use_parallel_gc_threads()) {
3740 satb_mq_set.set_par_closure(_task_id, NULL);
3741 } else {
3742 satb_mq_set.set_closure(NULL);
3743 }
3745 // again, this was a potentially expensive operation, decrease the
3746 // limits to get the regular clock call early
3747 decrease_limits();
3748 }
3750 void CMTask::print_stats() {
3751 gclog_or_tty->print_cr("Marking Stats, task = %d, calls = %d",
3752 _task_id, _calls);
3753 gclog_or_tty->print_cr(" Elapsed time = %1.2lfms, Termination time = %1.2lfms",
3754 _elapsed_time_ms, _termination_time_ms);
3755 gclog_or_tty->print_cr(" Step Times (cum): num = %d, avg = %1.2lfms, sd = %1.2lfms",
3756 _step_times_ms.num(), _step_times_ms.avg(),
3757 _step_times_ms.sd());
3758 gclog_or_tty->print_cr(" max = %1.2lfms, total = %1.2lfms",
3759 _step_times_ms.maximum(), _step_times_ms.sum());
3761 #if _MARKING_STATS_
3762 gclog_or_tty->print_cr(" Clock Intervals (cum): num = %d, avg = %1.2lfms, sd = %1.2lfms",
3763 _all_clock_intervals_ms.num(), _all_clock_intervals_ms.avg(),
3764 _all_clock_intervals_ms.sd());
3765 gclog_or_tty->print_cr(" max = %1.2lfms, total = %1.2lfms",
3766 _all_clock_intervals_ms.maximum(),
3767 _all_clock_intervals_ms.sum());
3768 gclog_or_tty->print_cr(" Clock Causes (cum): scanning = %d, marking = %d",
3769 _clock_due_to_scanning, _clock_due_to_marking);
3770 gclog_or_tty->print_cr(" Objects: scanned = %d, found on the bitmap = %d",
3771 _objs_scanned, _objs_found_on_bitmap);
3772 gclog_or_tty->print_cr(" Local Queue: pushes = %d, pops = %d, max size = %d",
3773 _local_pushes, _local_pops, _local_max_size);
3774 gclog_or_tty->print_cr(" Global Stack: pushes = %d, pops = %d, max size = %d",
3775 _global_pushes, _global_pops, _global_max_size);
3776 gclog_or_tty->print_cr(" transfers to = %d, transfers from = %d",
3777 _global_transfers_to,_global_transfers_from);
3778 gclog_or_tty->print_cr(" Regions: claimed = %d", _regions_claimed);
3779 gclog_or_tty->print_cr(" SATB buffers: processed = %d", _satb_buffers_processed);
3780 gclog_or_tty->print_cr(" Steals: attempts = %d, successes = %d",
3781 _steal_attempts, _steals);
3782 gclog_or_tty->print_cr(" Aborted: %d, due to", _aborted);
3783 gclog_or_tty->print_cr(" overflow: %d, global abort: %d, yield: %d",
3784 _aborted_overflow, _aborted_cm_aborted, _aborted_yield);
3785 gclog_or_tty->print_cr(" time out: %d, SATB: %d, termination: %d",
3786 _aborted_timed_out, _aborted_satb, _aborted_termination);
3787 #endif // _MARKING_STATS_
3788 }
3790 /*****************************************************************************
3792 The do_marking_step(time_target_ms) method is the building block
3793 of the parallel marking framework. It can be called in parallel
3794 with other invocations of do_marking_step() on different tasks
3795 (but only one per task, obviously) and concurrently with the
3796 mutator threads, or during remark, hence it eliminates the need
3797 for two versions of the code. When called during remark, it will
3798 pick up from where the task left off during the concurrent marking
3799 phase. Interestingly, tasks are also claimable during evacuation
3800 pauses too, since do_marking_step() ensures that it aborts before
3801 it needs to yield.
3803 The data structures that is uses to do marking work are the
3804 following:
3806 (1) Marking Bitmap. If there are gray objects that appear only
3807 on the bitmap (this happens either when dealing with an overflow
3808 or when the initial marking phase has simply marked the roots
3809 and didn't push them on the stack), then tasks claim heap
3810 regions whose bitmap they then scan to find gray objects. A
3811 global finger indicates where the end of the last claimed region
3812 is. A local finger indicates how far into the region a task has
3813 scanned. The two fingers are used to determine how to gray an
3814 object (i.e. whether simply marking it is OK, as it will be
3815 visited by a task in the future, or whether it needs to be also
3816 pushed on a stack).
3818 (2) Local Queue. The local queue of the task which is accessed
3819 reasonably efficiently by the task. Other tasks can steal from
3820 it when they run out of work. Throughout the marking phase, a
3821 task attempts to keep its local queue short but not totally
3822 empty, so that entries are available for stealing by other
3823 tasks. Only when there is no more work, a task will totally
3824 drain its local queue.
3826 (3) Global Mark Stack. This handles local queue overflow. During
3827 marking only sets of entries are moved between it and the local
3828 queues, as access to it requires a mutex and more fine-grain
3829 interaction with it which might cause contention. If it
3830 overflows, then the marking phase should restart and iterate
3831 over the bitmap to identify gray objects. Throughout the marking
3832 phase, tasks attempt to keep the global mark stack at a small
3833 length but not totally empty, so that entries are available for
3834 popping by other tasks. Only when there is no more work, tasks
3835 will totally drain the global mark stack.
3837 (4) SATB Buffer Queue. This is where completed SATB buffers are
3838 made available. Buffers are regularly removed from this queue
3839 and scanned for roots, so that the queue doesn't get too
3840 long. During remark, all completed buffers are processed, as
3841 well as the filled in parts of any uncompleted buffers.
3843 The do_marking_step() method tries to abort when the time target
3844 has been reached. There are a few other cases when the
3845 do_marking_step() method also aborts:
3847 (1) When the marking phase has been aborted (after a Full GC).
3849 (2) When a global overflow (on the global stack) has been
3850 triggered. Before the task aborts, it will actually sync up with
3851 the other tasks to ensure that all the marking data structures
3852 (local queues, stacks, fingers etc.) are re-initialised so that
3853 when do_marking_step() completes, the marking phase can
3854 immediately restart.
3856 (3) When enough completed SATB buffers are available. The
3857 do_marking_step() method only tries to drain SATB buffers right
3858 at the beginning. So, if enough buffers are available, the
3859 marking step aborts and the SATB buffers are processed at
3860 the beginning of the next invocation.
3862 (4) To yield. when we have to yield then we abort and yield
3863 right at the end of do_marking_step(). This saves us from a lot
3864 of hassle as, by yielding we might allow a Full GC. If this
3865 happens then objects will be compacted underneath our feet, the
3866 heap might shrink, etc. We save checking for this by just
3867 aborting and doing the yield right at the end.
3869 From the above it follows that the do_marking_step() method should
3870 be called in a loop (or, otherwise, regularly) until it completes.
3872 If a marking step completes without its has_aborted() flag being
3873 true, it means it has completed the current marking phase (and
3874 also all other marking tasks have done so and have all synced up).
3876 A method called regular_clock_call() is invoked "regularly" (in
3877 sub ms intervals) throughout marking. It is this clock method that
3878 checks all the abort conditions which were mentioned above and
3879 decides when the task should abort. A work-based scheme is used to
3880 trigger this clock method: when the number of object words the
3881 marking phase has scanned or the number of references the marking
3882 phase has visited reach a given limit. Additional invocations to
3883 the method clock have been planted in a few other strategic places
3884 too. The initial reason for the clock method was to avoid calling
3885 vtime too regularly, as it is quite expensive. So, once it was in
3886 place, it was natural to piggy-back all the other conditions on it
3887 too and not constantly check them throughout the code.
3889 *****************************************************************************/
3891 void CMTask::do_marking_step(double time_target_ms,
3892 bool do_stealing,
3893 bool do_termination) {
3894 assert(time_target_ms >= 1.0, "minimum granularity is 1ms");
3895 assert(concurrent() == _cm->concurrent(), "they should be the same");
3897 G1CollectorPolicy* g1_policy = _g1h->g1_policy();
3898 assert(_task_queues != NULL, "invariant");
3899 assert(_task_queue != NULL, "invariant");
3900 assert(_task_queues->queue(_task_id) == _task_queue, "invariant");
3902 assert(!_claimed,
3903 "only one thread should claim this task at any one time");
3905 // OK, this doesn't safeguard again all possible scenarios, as it is
3906 // possible for two threads to set the _claimed flag at the same
3907 // time. But it is only for debugging purposes anyway and it will
3908 // catch most problems.
3909 _claimed = true;
3911 _start_time_ms = os::elapsedVTime() * 1000.0;
3912 statsOnly( _interval_start_time_ms = _start_time_ms );
3914 double diff_prediction_ms =
3915 g1_policy->get_new_prediction(&_marking_step_diffs_ms);
3916 _time_target_ms = time_target_ms - diff_prediction_ms;
3918 // set up the variables that are used in the work-based scheme to
3919 // call the regular clock method
3920 _words_scanned = 0;
3921 _refs_reached = 0;
3922 recalculate_limits();
3924 // clear all flags
3925 clear_has_aborted();
3926 _has_timed_out = false;
3927 _draining_satb_buffers = false;
3929 ++_calls;
3931 if (_cm->verbose_low()) {
3932 gclog_or_tty->print_cr("[%d] >>>>>>>>>> START, call = %d, "
3933 "target = %1.2lfms >>>>>>>>>>",
3934 _task_id, _calls, _time_target_ms);
3935 }
3937 // Set up the bitmap and oop closures. Anything that uses them is
3938 // eventually called from this method, so it is OK to allocate these
3939 // statically.
3940 CMBitMapClosure bitmap_closure(this, _cm, _nextMarkBitMap);
3941 G1CMOopClosure cm_oop_closure(_g1h, _cm, this);
3942 set_cm_oop_closure(&cm_oop_closure);
3944 if (_cm->has_overflown()) {
3945 // This can happen if the mark stack overflows during a GC pause
3946 // and this task, after a yield point, restarts. We have to abort
3947 // as we need to get into the overflow protocol which happens
3948 // right at the end of this task.
3949 set_has_aborted();
3950 }
3952 // First drain any available SATB buffers. After this, we will not
3953 // look at SATB buffers before the next invocation of this method.
3954 // If enough completed SATB buffers are queued up, the regular clock
3955 // will abort this task so that it restarts.
3956 drain_satb_buffers();
3957 // ...then partially drain the local queue and the global stack
3958 drain_local_queue(true);
3959 drain_global_stack(true);
3961 do {
3962 if (!has_aborted() && _curr_region != NULL) {
3963 // This means that we're already holding on to a region.
3964 assert(_finger != NULL, "if region is not NULL, then the finger "
3965 "should not be NULL either");
3967 // We might have restarted this task after an evacuation pause
3968 // which might have evacuated the region we're holding on to
3969 // underneath our feet. Let's read its limit again to make sure
3970 // that we do not iterate over a region of the heap that
3971 // contains garbage (update_region_limit() will also move
3972 // _finger to the start of the region if it is found empty).
3973 update_region_limit();
3974 // We will start from _finger not from the start of the region,
3975 // as we might be restarting this task after aborting half-way
3976 // through scanning this region. In this case, _finger points to
3977 // the address where we last found a marked object. If this is a
3978 // fresh region, _finger points to start().
3979 MemRegion mr = MemRegion(_finger, _region_limit);
3981 if (_cm->verbose_low()) {
3982 gclog_or_tty->print_cr("[%d] we're scanning part "
3983 "["PTR_FORMAT", "PTR_FORMAT") "
3984 "of region "PTR_FORMAT,
3985 _task_id, _finger, _region_limit, _curr_region);
3986 }
3988 // Let's iterate over the bitmap of the part of the
3989 // region that is left.
3990 if (mr.is_empty() || _nextMarkBitMap->iterate(&bitmap_closure, mr)) {
3991 // We successfully completed iterating over the region. Now,
3992 // let's give up the region.
3993 giveup_current_region();
3994 regular_clock_call();
3995 } else {
3996 assert(has_aborted(), "currently the only way to do so");
3997 // The only way to abort the bitmap iteration is to return
3998 // false from the do_bit() method. However, inside the
3999 // do_bit() method we move the _finger to point to the
4000 // object currently being looked at. So, if we bail out, we
4001 // have definitely set _finger to something non-null.
4002 assert(_finger != NULL, "invariant");
4004 // Region iteration was actually aborted. So now _finger
4005 // points to the address of the object we last scanned. If we
4006 // leave it there, when we restart this task, we will rescan
4007 // the object. It is easy to avoid this. We move the finger by
4008 // enough to point to the next possible object header (the
4009 // bitmap knows by how much we need to move it as it knows its
4010 // granularity).
4011 assert(_finger < _region_limit, "invariant");
4012 HeapWord* new_finger = _nextMarkBitMap->nextWord(_finger);
4013 // Check if bitmap iteration was aborted while scanning the last object
4014 if (new_finger >= _region_limit) {
4015 giveup_current_region();
4016 } else {
4017 move_finger_to(new_finger);
4018 }
4019 }
4020 }
4021 // At this point we have either completed iterating over the
4022 // region we were holding on to, or we have aborted.
4024 // We then partially drain the local queue and the global stack.
4025 // (Do we really need this?)
4026 drain_local_queue(true);
4027 drain_global_stack(true);
4029 // Read the note on the claim_region() method on why it might
4030 // return NULL with potentially more regions available for
4031 // claiming and why we have to check out_of_regions() to determine
4032 // whether we're done or not.
4033 while (!has_aborted() && _curr_region == NULL && !_cm->out_of_regions()) {
4034 // We are going to try to claim a new region. We should have
4035 // given up on the previous one.
4036 // Separated the asserts so that we know which one fires.
4037 assert(_curr_region == NULL, "invariant");
4038 assert(_finger == NULL, "invariant");
4039 assert(_region_limit == NULL, "invariant");
4040 if (_cm->verbose_low()) {
4041 gclog_or_tty->print_cr("[%d] trying to claim a new region", _task_id);
4042 }
4043 HeapRegion* claimed_region = _cm->claim_region(_task_id);
4044 if (claimed_region != NULL) {
4045 // Yes, we managed to claim one
4046 statsOnly( ++_regions_claimed );
4048 if (_cm->verbose_low()) {
4049 gclog_or_tty->print_cr("[%d] we successfully claimed "
4050 "region "PTR_FORMAT,
4051 _task_id, claimed_region);
4052 }
4054 setup_for_region(claimed_region);
4055 assert(_curr_region == claimed_region, "invariant");
4056 }
4057 // It is important to call the regular clock here. It might take
4058 // a while to claim a region if, for example, we hit a large
4059 // block of empty regions. So we need to call the regular clock
4060 // method once round the loop to make sure it's called
4061 // frequently enough.
4062 regular_clock_call();
4063 }
4065 if (!has_aborted() && _curr_region == NULL) {
4066 assert(_cm->out_of_regions(),
4067 "at this point we should be out of regions");
4068 }
4069 } while ( _curr_region != NULL && !has_aborted());
4071 if (!has_aborted()) {
4072 // We cannot check whether the global stack is empty, since other
4073 // tasks might be pushing objects to it concurrently.
4074 assert(_cm->out_of_regions(),
4075 "at this point we should be out of regions");
4077 if (_cm->verbose_low()) {
4078 gclog_or_tty->print_cr("[%d] all regions claimed", _task_id);
4079 }
4081 // Try to reduce the number of available SATB buffers so that
4082 // remark has less work to do.
4083 drain_satb_buffers();
4084 }
4086 // Since we've done everything else, we can now totally drain the
4087 // local queue and global stack.
4088 drain_local_queue(false);
4089 drain_global_stack(false);
4091 // Attempt at work stealing from other task's queues.
4092 if (do_stealing && !has_aborted()) {
4093 // We have not aborted. This means that we have finished all that
4094 // we could. Let's try to do some stealing...
4096 // We cannot check whether the global stack is empty, since other
4097 // tasks might be pushing objects to it concurrently.
4098 assert(_cm->out_of_regions() && _task_queue->size() == 0,
4099 "only way to reach here");
4101 if (_cm->verbose_low()) {
4102 gclog_or_tty->print_cr("[%d] starting to steal", _task_id);
4103 }
4105 while (!has_aborted()) {
4106 oop obj;
4107 statsOnly( ++_steal_attempts );
4109 if (_cm->try_stealing(_task_id, &_hash_seed, obj)) {
4110 if (_cm->verbose_medium()) {
4111 gclog_or_tty->print_cr("[%d] stolen "PTR_FORMAT" successfully",
4112 _task_id, (void*) obj);
4113 }
4115 statsOnly( ++_steals );
4117 assert(_nextMarkBitMap->isMarked((HeapWord*) obj),
4118 "any stolen object should be marked");
4119 scan_object(obj);
4121 // And since we're towards the end, let's totally drain the
4122 // local queue and global stack.
4123 drain_local_queue(false);
4124 drain_global_stack(false);
4125 } else {
4126 break;
4127 }
4128 }
4129 }
4131 // If we are about to wrap up and go into termination, check if we
4132 // should raise the overflow flag.
4133 if (do_termination && !has_aborted()) {
4134 if (_cm->force_overflow()->should_force()) {
4135 _cm->set_has_overflown();
4136 regular_clock_call();
4137 }
4138 }
4140 // We still haven't aborted. Now, let's try to get into the
4141 // termination protocol.
4142 if (do_termination && !has_aborted()) {
4143 // We cannot check whether the global stack is empty, since other
4144 // tasks might be concurrently pushing objects on it.
4145 // Separated the asserts so that we know which one fires.
4146 assert(_cm->out_of_regions(), "only way to reach here");
4147 assert(_task_queue->size() == 0, "only way to reach here");
4149 if (_cm->verbose_low()) {
4150 gclog_or_tty->print_cr("[%d] starting termination protocol", _task_id);
4151 }
4153 _termination_start_time_ms = os::elapsedVTime() * 1000.0;
4154 // The CMTask class also extends the TerminatorTerminator class,
4155 // hence its should_exit_termination() method will also decide
4156 // whether to exit the termination protocol or not.
4157 bool finished = _cm->terminator()->offer_termination(this);
4158 double termination_end_time_ms = os::elapsedVTime() * 1000.0;
4159 _termination_time_ms +=
4160 termination_end_time_ms - _termination_start_time_ms;
4162 if (finished) {
4163 // We're all done.
4165 if (_task_id == 0) {
4166 // let's allow task 0 to do this
4167 if (concurrent()) {
4168 assert(_cm->concurrent_marking_in_progress(), "invariant");
4169 // we need to set this to false before the next
4170 // safepoint. This way we ensure that the marking phase
4171 // doesn't observe any more heap expansions.
4172 _cm->clear_concurrent_marking_in_progress();
4173 }
4174 }
4176 // We can now guarantee that the global stack is empty, since
4177 // all other tasks have finished. We separated the guarantees so
4178 // that, if a condition is false, we can immediately find out
4179 // which one.
4180 guarantee(_cm->out_of_regions(), "only way to reach here");
4181 guarantee(_cm->mark_stack_empty(), "only way to reach here");
4182 guarantee(_task_queue->size() == 0, "only way to reach here");
4183 guarantee(!_cm->has_overflown(), "only way to reach here");
4184 guarantee(!_cm->mark_stack_overflow(), "only way to reach here");
4186 if (_cm->verbose_low()) {
4187 gclog_or_tty->print_cr("[%d] all tasks terminated", _task_id);
4188 }
4189 } else {
4190 // Apparently there's more work to do. Let's abort this task. It
4191 // will restart it and we can hopefully find more things to do.
4193 if (_cm->verbose_low()) {
4194 gclog_or_tty->print_cr("[%d] apparently there is more work to do",
4195 _task_id);
4196 }
4198 set_has_aborted();
4199 statsOnly( ++_aborted_termination );
4200 }
4201 }
4203 // Mainly for debugging purposes to make sure that a pointer to the
4204 // closure which was statically allocated in this frame doesn't
4205 // escape it by accident.
4206 set_cm_oop_closure(NULL);
4207 double end_time_ms = os::elapsedVTime() * 1000.0;
4208 double elapsed_time_ms = end_time_ms - _start_time_ms;
4209 // Update the step history.
4210 _step_times_ms.add(elapsed_time_ms);
4212 if (has_aborted()) {
4213 // The task was aborted for some reason.
4215 statsOnly( ++_aborted );
4217 if (_has_timed_out) {
4218 double diff_ms = elapsed_time_ms - _time_target_ms;
4219 // Keep statistics of how well we did with respect to hitting
4220 // our target only if we actually timed out (if we aborted for
4221 // other reasons, then the results might get skewed).
4222 _marking_step_diffs_ms.add(diff_ms);
4223 }
4225 if (_cm->has_overflown()) {
4226 // This is the interesting one. We aborted because a global
4227 // overflow was raised. This means we have to restart the
4228 // marking phase and start iterating over regions. However, in
4229 // order to do this we have to make sure that all tasks stop
4230 // what they are doing and re-initialise in a safe manner. We
4231 // will achieve this with the use of two barrier sync points.
4233 if (_cm->verbose_low()) {
4234 gclog_or_tty->print_cr("[%d] detected overflow", _task_id);
4235 }
4237 _cm->enter_first_sync_barrier(_task_id);
4238 // When we exit this sync barrier we know that all tasks have
4239 // stopped doing marking work. So, it's now safe to
4240 // re-initialise our data structures. At the end of this method,
4241 // task 0 will clear the global data structures.
4243 statsOnly( ++_aborted_overflow );
4245 // We clear the local state of this task...
4246 clear_region_fields();
4248 // ...and enter the second barrier.
4249 _cm->enter_second_sync_barrier(_task_id);
4250 // At this point everything has bee re-initialised and we're
4251 // ready to restart.
4252 }
4254 if (_cm->verbose_low()) {
4255 gclog_or_tty->print_cr("[%d] <<<<<<<<<< ABORTING, target = %1.2lfms, "
4256 "elapsed = %1.2lfms <<<<<<<<<<",
4257 _task_id, _time_target_ms, elapsed_time_ms);
4258 if (_cm->has_aborted()) {
4259 gclog_or_tty->print_cr("[%d] ========== MARKING ABORTED ==========",
4260 _task_id);
4261 }
4262 }
4263 } else {
4264 if (_cm->verbose_low()) {
4265 gclog_or_tty->print_cr("[%d] <<<<<<<<<< FINISHED, target = %1.2lfms, "
4266 "elapsed = %1.2lfms <<<<<<<<<<",
4267 _task_id, _time_target_ms, elapsed_time_ms);
4268 }
4269 }
4271 _claimed = false;
4272 }
4274 CMTask::CMTask(int task_id,
4275 ConcurrentMark* cm,
4276 size_t* marked_bytes,
4277 BitMap* card_bm,
4278 CMTaskQueue* task_queue,
4279 CMTaskQueueSet* task_queues)
4280 : _g1h(G1CollectedHeap::heap()),
4281 _task_id(task_id), _cm(cm),
4282 _claimed(false),
4283 _nextMarkBitMap(NULL), _hash_seed(17),
4284 _task_queue(task_queue),
4285 _task_queues(task_queues),
4286 _cm_oop_closure(NULL),
4287 _marked_bytes_array(marked_bytes),
4288 _card_bm(card_bm) {
4289 guarantee(task_queue != NULL, "invariant");
4290 guarantee(task_queues != NULL, "invariant");
4292 statsOnly( _clock_due_to_scanning = 0;
4293 _clock_due_to_marking = 0 );
4295 _marking_step_diffs_ms.add(0.5);
4296 }
4298 // These are formatting macros that are used below to ensure
4299 // consistent formatting. The *_H_* versions are used to format the
4300 // header for a particular value and they should be kept consistent
4301 // with the corresponding macro. Also note that most of the macros add
4302 // the necessary white space (as a prefix) which makes them a bit
4303 // easier to compose.
4305 // All the output lines are prefixed with this string to be able to
4306 // identify them easily in a large log file.
4307 #define G1PPRL_LINE_PREFIX "###"
4309 #define G1PPRL_ADDR_BASE_FORMAT " "PTR_FORMAT"-"PTR_FORMAT
4310 #ifdef _LP64
4311 #define G1PPRL_ADDR_BASE_H_FORMAT " %37s"
4312 #else // _LP64
4313 #define G1PPRL_ADDR_BASE_H_FORMAT " %21s"
4314 #endif // _LP64
4316 // For per-region info
4317 #define G1PPRL_TYPE_FORMAT " %-4s"
4318 #define G1PPRL_TYPE_H_FORMAT " %4s"
4319 #define G1PPRL_BYTE_FORMAT " "SIZE_FORMAT_W(9)
4320 #define G1PPRL_BYTE_H_FORMAT " %9s"
4321 #define G1PPRL_DOUBLE_FORMAT " %14.1f"
4322 #define G1PPRL_DOUBLE_H_FORMAT " %14s"
4324 // For summary info
4325 #define G1PPRL_SUM_ADDR_FORMAT(tag) " "tag":"G1PPRL_ADDR_BASE_FORMAT
4326 #define G1PPRL_SUM_BYTE_FORMAT(tag) " "tag": "SIZE_FORMAT
4327 #define G1PPRL_SUM_MB_FORMAT(tag) " "tag": %1.2f MB"
4328 #define G1PPRL_SUM_MB_PERC_FORMAT(tag) G1PPRL_SUM_MB_FORMAT(tag)" / %1.2f %%"
4330 G1PrintRegionLivenessInfoClosure::
4331 G1PrintRegionLivenessInfoClosure(outputStream* out, const char* phase_name)
4332 : _out(out),
4333 _total_used_bytes(0), _total_capacity_bytes(0),
4334 _total_prev_live_bytes(0), _total_next_live_bytes(0),
4335 _hum_used_bytes(0), _hum_capacity_bytes(0),
4336 _hum_prev_live_bytes(0), _hum_next_live_bytes(0) {
4337 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4338 MemRegion g1_committed = g1h->g1_committed();
4339 MemRegion g1_reserved = g1h->g1_reserved();
4340 double now = os::elapsedTime();
4342 // Print the header of the output.
4343 _out->cr();
4344 _out->print_cr(G1PPRL_LINE_PREFIX" PHASE %s @ %1.3f", phase_name, now);
4345 _out->print_cr(G1PPRL_LINE_PREFIX" HEAP"
4346 G1PPRL_SUM_ADDR_FORMAT("committed")
4347 G1PPRL_SUM_ADDR_FORMAT("reserved")
4348 G1PPRL_SUM_BYTE_FORMAT("region-size"),
4349 g1_committed.start(), g1_committed.end(),
4350 g1_reserved.start(), g1_reserved.end(),
4351 HeapRegion::GrainBytes);
4352 _out->print_cr(G1PPRL_LINE_PREFIX);
4353 _out->print_cr(G1PPRL_LINE_PREFIX
4354 G1PPRL_TYPE_H_FORMAT
4355 G1PPRL_ADDR_BASE_H_FORMAT
4356 G1PPRL_BYTE_H_FORMAT
4357 G1PPRL_BYTE_H_FORMAT
4358 G1PPRL_BYTE_H_FORMAT
4359 G1PPRL_DOUBLE_H_FORMAT,
4360 "type", "address-range",
4361 "used", "prev-live", "next-live", "gc-eff");
4362 _out->print_cr(G1PPRL_LINE_PREFIX
4363 G1PPRL_TYPE_H_FORMAT
4364 G1PPRL_ADDR_BASE_H_FORMAT
4365 G1PPRL_BYTE_H_FORMAT
4366 G1PPRL_BYTE_H_FORMAT
4367 G1PPRL_BYTE_H_FORMAT
4368 G1PPRL_DOUBLE_H_FORMAT,
4369 "", "",
4370 "(bytes)", "(bytes)", "(bytes)", "(bytes/ms)");
4371 }
4373 // It takes as a parameter a reference to one of the _hum_* fields, it
4374 // deduces the corresponding value for a region in a humongous region
4375 // series (either the region size, or what's left if the _hum_* field
4376 // is < the region size), and updates the _hum_* field accordingly.
4377 size_t G1PrintRegionLivenessInfoClosure::get_hum_bytes(size_t* hum_bytes) {
4378 size_t bytes = 0;
4379 // The > 0 check is to deal with the prev and next live bytes which
4380 // could be 0.
4381 if (*hum_bytes > 0) {
4382 bytes = MIN2(HeapRegion::GrainBytes, *hum_bytes);
4383 *hum_bytes -= bytes;
4384 }
4385 return bytes;
4386 }
4388 // It deduces the values for a region in a humongous region series
4389 // from the _hum_* fields and updates those accordingly. It assumes
4390 // that that _hum_* fields have already been set up from the "starts
4391 // humongous" region and we visit the regions in address order.
4392 void G1PrintRegionLivenessInfoClosure::get_hum_bytes(size_t* used_bytes,
4393 size_t* capacity_bytes,
4394 size_t* prev_live_bytes,
4395 size_t* next_live_bytes) {
4396 assert(_hum_used_bytes > 0 && _hum_capacity_bytes > 0, "pre-condition");
4397 *used_bytes = get_hum_bytes(&_hum_used_bytes);
4398 *capacity_bytes = get_hum_bytes(&_hum_capacity_bytes);
4399 *prev_live_bytes = get_hum_bytes(&_hum_prev_live_bytes);
4400 *next_live_bytes = get_hum_bytes(&_hum_next_live_bytes);
4401 }
4403 bool G1PrintRegionLivenessInfoClosure::doHeapRegion(HeapRegion* r) {
4404 const char* type = "";
4405 HeapWord* bottom = r->bottom();
4406 HeapWord* end = r->end();
4407 size_t capacity_bytes = r->capacity();
4408 size_t used_bytes = r->used();
4409 size_t prev_live_bytes = r->live_bytes();
4410 size_t next_live_bytes = r->next_live_bytes();
4411 double gc_eff = r->gc_efficiency();
4412 if (r->used() == 0) {
4413 type = "FREE";
4414 } else if (r->is_survivor()) {
4415 type = "SURV";
4416 } else if (r->is_young()) {
4417 type = "EDEN";
4418 } else if (r->startsHumongous()) {
4419 type = "HUMS";
4421 assert(_hum_used_bytes == 0 && _hum_capacity_bytes == 0 &&
4422 _hum_prev_live_bytes == 0 && _hum_next_live_bytes == 0,
4423 "they should have been zeroed after the last time we used them");
4424 // Set up the _hum_* fields.
4425 _hum_capacity_bytes = capacity_bytes;
4426 _hum_used_bytes = used_bytes;
4427 _hum_prev_live_bytes = prev_live_bytes;
4428 _hum_next_live_bytes = next_live_bytes;
4429 get_hum_bytes(&used_bytes, &capacity_bytes,
4430 &prev_live_bytes, &next_live_bytes);
4431 end = bottom + HeapRegion::GrainWords;
4432 } else if (r->continuesHumongous()) {
4433 type = "HUMC";
4434 get_hum_bytes(&used_bytes, &capacity_bytes,
4435 &prev_live_bytes, &next_live_bytes);
4436 assert(end == bottom + HeapRegion::GrainWords, "invariant");
4437 } else {
4438 type = "OLD";
4439 }
4441 _total_used_bytes += used_bytes;
4442 _total_capacity_bytes += capacity_bytes;
4443 _total_prev_live_bytes += prev_live_bytes;
4444 _total_next_live_bytes += next_live_bytes;
4446 // Print a line for this particular region.
4447 _out->print_cr(G1PPRL_LINE_PREFIX
4448 G1PPRL_TYPE_FORMAT
4449 G1PPRL_ADDR_BASE_FORMAT
4450 G1PPRL_BYTE_FORMAT
4451 G1PPRL_BYTE_FORMAT
4452 G1PPRL_BYTE_FORMAT
4453 G1PPRL_DOUBLE_FORMAT,
4454 type, bottom, end,
4455 used_bytes, prev_live_bytes, next_live_bytes, gc_eff);
4457 return false;
4458 }
4460 G1PrintRegionLivenessInfoClosure::~G1PrintRegionLivenessInfoClosure() {
4461 // Print the footer of the output.
4462 _out->print_cr(G1PPRL_LINE_PREFIX);
4463 _out->print_cr(G1PPRL_LINE_PREFIX
4464 " SUMMARY"
4465 G1PPRL_SUM_MB_FORMAT("capacity")
4466 G1PPRL_SUM_MB_PERC_FORMAT("used")
4467 G1PPRL_SUM_MB_PERC_FORMAT("prev-live")
4468 G1PPRL_SUM_MB_PERC_FORMAT("next-live"),
4469 bytes_to_mb(_total_capacity_bytes),
4470 bytes_to_mb(_total_used_bytes),
4471 perc(_total_used_bytes, _total_capacity_bytes),
4472 bytes_to_mb(_total_prev_live_bytes),
4473 perc(_total_prev_live_bytes, _total_capacity_bytes),
4474 bytes_to_mb(_total_next_live_bytes),
4475 perc(_total_next_live_bytes, _total_capacity_bytes));
4476 _out->cr();
4477 }