1 /*
2 * Copyright (c) 2001, 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/metadataOnStackMark.hpp"
27 #include "classfile/symbolTable.hpp"
28 #include "code/codeCache.hpp"
29 #include "gc_implementation/g1/concurrentMark.inline.hpp"
30 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
31 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
32 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
33 #include "gc_implementation/g1/g1ErgoVerbose.hpp"
34 #include "gc_implementation/g1/g1Log.hpp"
35 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
36 #include "gc_implementation/g1/g1RemSet.hpp"
37 #include "gc_implementation/g1/heapRegion.inline.hpp"
38 #include "gc_implementation/g1/heapRegionManager.inline.hpp"
39 #include "gc_implementation/g1/heapRegionRemSet.hpp"
40 #include "gc_implementation/g1/heapRegionSet.inline.hpp"
41 #include "gc_implementation/shared/vmGCOperations.hpp"
42 #include "gc_implementation/shared/gcTimer.hpp"
43 #include "gc_implementation/shared/gcTrace.hpp"
44 #include "gc_implementation/shared/gcTraceTime.hpp"
45 #include "memory/allocation.hpp"
46 #include "memory/genOopClosures.inline.hpp"
47 #include "memory/referencePolicy.hpp"
48 #include "memory/resourceArea.hpp"
49 #include "oops/oop.inline.hpp"
50 #include "runtime/handles.inline.hpp"
51 #include "runtime/java.hpp"
52 #include "runtime/atomic.inline.hpp"
53 #include "runtime/prefetch.inline.hpp"
54 #include "services/memTracker.hpp"
55
56 // Concurrent marking bit map wrapper
57
58 CMBitMapRO::CMBitMapRO(int shifter) :
59 _bm(),
60 _shifter(shifter) {
61 _bmStartWord = 0;
62 _bmWordSize = 0;
63 }
64
65 HeapWord* CMBitMapRO::getNextMarkedWordAddress(const HeapWord* addr,
66 const HeapWord* limit) const {
67 // First we must round addr *up* to a possible object boundary.
68 addr = (HeapWord*)align_size_up((intptr_t)addr,
69 HeapWordSize << _shifter);
70 size_t addrOffset = heapWordToOffset(addr);
71 if (limit == NULL) {
72 limit = _bmStartWord + _bmWordSize;
73 }
74 size_t limitOffset = heapWordToOffset(limit);
75 size_t nextOffset = _bm.get_next_one_offset(addrOffset, limitOffset);
76 HeapWord* nextAddr = offsetToHeapWord(nextOffset);
77 assert(nextAddr >= addr, "get_next_one postcondition");
78 assert(nextAddr == limit || isMarked(nextAddr),
79 "get_next_one postcondition");
80 return nextAddr;
81 }
82
83 HeapWord* CMBitMapRO::getNextUnmarkedWordAddress(const HeapWord* addr,
84 const HeapWord* limit) const {
85 size_t addrOffset = heapWordToOffset(addr);
86 if (limit == NULL) {
87 limit = _bmStartWord + _bmWordSize;
88 }
89 size_t limitOffset = heapWordToOffset(limit);
90 size_t nextOffset = _bm.get_next_zero_offset(addrOffset, limitOffset);
91 HeapWord* nextAddr = offsetToHeapWord(nextOffset);
92 assert(nextAddr >= addr, "get_next_one postcondition");
93 assert(nextAddr == limit || !isMarked(nextAddr),
94 "get_next_one postcondition");
95 return nextAddr;
96 }
97
98 int CMBitMapRO::heapWordDiffToOffsetDiff(size_t diff) const {
99 assert((diff & ((1 << _shifter) - 1)) == 0, "argument check");
100 return (int) (diff >> _shifter);
101 }
102
103 #ifndef PRODUCT
104 bool CMBitMapRO::covers(MemRegion heap_rs) const {
105 // assert(_bm.map() == _virtual_space.low(), "map inconsistency");
106 assert(((size_t)_bm.size() * ((size_t)1 << _shifter)) == _bmWordSize,
107 "size inconsistency");
108 return _bmStartWord == (HeapWord*)(heap_rs.start()) &&
109 _bmWordSize == heap_rs.word_size();
110 }
111 #endif
112
113 void CMBitMapRO::print_on_error(outputStream* st, const char* prefix) const {
114 _bm.print_on_error(st, prefix);
115 }
116
117 size_t CMBitMap::compute_size(size_t heap_size) {
118 return heap_size / mark_distance();
119 }
120
121 size_t CMBitMap::mark_distance() {
122 return MinObjAlignmentInBytes * BitsPerByte;
123 }
124
125 void CMBitMap::initialize(MemRegion heap, G1RegionToSpaceMapper* storage) {
126 _bmStartWord = heap.start();
127 _bmWordSize = heap.word_size();
128
129 _bm.set_map((BitMap::bm_word_t*) storage->reserved().start());
130 _bm.set_size(_bmWordSize >> _shifter);
131
132 storage->set_mapping_changed_listener(&_listener);
133 }
134
135 void CMBitMapMappingChangedListener::on_commit(uint start_region, size_t num_regions, bool zero_filled) {
136 if (zero_filled) {
137 return;
138 }
139 // We need to clear the bitmap on commit, removing any existing information.
140 MemRegion mr(G1CollectedHeap::heap()->bottom_addr_for_region(start_region), num_regions * HeapRegion::GrainWords);
141 _bm->clearRange(mr);
142 }
143
144 // Closure used for clearing the given mark bitmap.
145 class ClearBitmapHRClosure : public HeapRegionClosure {
146 private:
147 ConcurrentMark* _cm;
148 CMBitMap* _bitmap;
149 bool _may_yield; // The closure may yield during iteration. If yielded, abort the iteration.
150 public:
151 ClearBitmapHRClosure(ConcurrentMark* cm, CMBitMap* bitmap, bool may_yield) : HeapRegionClosure(), _cm(cm), _bitmap(bitmap), _may_yield(may_yield) {
152 assert(!may_yield || cm != NULL, "CM must be non-NULL if this closure is expected to yield.");
153 }
154
155 virtual bool doHeapRegion(HeapRegion* r) {
156 size_t const chunk_size_in_words = M / HeapWordSize;
157
158 HeapWord* cur = r->bottom();
159 HeapWord* const end = r->end();
160
161 while (cur < end) {
162 MemRegion mr(cur, MIN2(cur + chunk_size_in_words, end));
163 _bitmap->clearRange(mr);
164
165 cur += chunk_size_in_words;
166
167 // Abort iteration if after yielding the marking has been aborted.
168 if (_may_yield && _cm->do_yield_check() && _cm->has_aborted()) {
169 return true;
170 }
171 // Repeat the asserts from before the start of the closure. We will do them
172 // as asserts here to minimize their overhead on the product. However, we
173 // will have them as guarantees at the beginning / end of the bitmap
174 // clearing to get some checking in the product.
175 assert(!_may_yield || _cm->cmThread()->during_cycle(), "invariant");
176 assert(!_may_yield || !G1CollectedHeap::heap()->mark_in_progress(), "invariant");
177 }
178
179 return false;
180 }
181 };
182
183 class ParClearNextMarkBitmapTask : public AbstractGangTask {
184 ClearBitmapHRClosure* _cl;
185 HeapRegionClaimer _hrclaimer;
186 bool _suspendible; // If the task is suspendible, workers must join the STS.
187
188 public:
189 ParClearNextMarkBitmapTask(ClearBitmapHRClosure *cl, uint n_workers, bool suspendible) :
190 _cl(cl), _suspendible(suspendible), AbstractGangTask("Parallel Clear Bitmap Task"), _hrclaimer(n_workers) {}
191
192 void work(uint worker_id) {
193 if (_suspendible) {
194 SuspendibleThreadSet::join();
195 }
196 G1CollectedHeap::heap()->heap_region_par_iterate(_cl, worker_id, &_hrclaimer, true);
197 if (_suspendible) {
198 SuspendibleThreadSet::leave();
199 }
200 }
201 };
202
203 void CMBitMap::clearAll() {
204 G1CollectedHeap* g1h = G1CollectedHeap::heap();
205 ClearBitmapHRClosure cl(NULL, this, false /* may_yield */);
206 uint n_workers = g1h->workers()->active_workers();
207 ParClearNextMarkBitmapTask task(&cl, n_workers, false);
208 g1h->workers()->run_task(&task);
209 guarantee(cl.complete(), "Must have completed iteration.");
210 return;
211 }
212
213 void CMBitMap::markRange(MemRegion mr) {
214 mr.intersection(MemRegion(_bmStartWord, _bmWordSize));
215 assert(!mr.is_empty(), "unexpected empty region");
216 assert((offsetToHeapWord(heapWordToOffset(mr.end())) ==
217 ((HeapWord *) mr.end())),
218 "markRange memory region end is not card aligned");
219 // convert address range into offset range
220 _bm.at_put_range(heapWordToOffset(mr.start()),
221 heapWordToOffset(mr.end()), true);
222 }
223
224 void CMBitMap::clearRange(MemRegion mr) {
225 mr.intersection(MemRegion(_bmStartWord, _bmWordSize));
226 assert(!mr.is_empty(), "unexpected empty region");
227 // convert address range into offset range
228 _bm.at_put_range(heapWordToOffset(mr.start()),
229 heapWordToOffset(mr.end()), false);
230 }
231
232 MemRegion CMBitMap::getAndClearMarkedRegion(HeapWord* addr,
233 HeapWord* end_addr) {
234 HeapWord* start = getNextMarkedWordAddress(addr);
235 start = MIN2(start, end_addr);
236 HeapWord* end = getNextUnmarkedWordAddress(start);
237 end = MIN2(end, end_addr);
238 assert(start <= end, "Consistency check");
239 MemRegion mr(start, end);
240 if (!mr.is_empty()) {
241 clearRange(mr);
242 }
243 return mr;
244 }
245
246 CMMarkStack::CMMarkStack(ConcurrentMark* cm) :
247 _base(NULL), _cm(cm)
248 #ifdef ASSERT
249 , _drain_in_progress(false)
250 , _drain_in_progress_yields(false)
251 #endif
252 {}
253
254 bool CMMarkStack::allocate(size_t capacity) {
255 // allocate a stack of the requisite depth
256 ReservedSpace rs(ReservedSpace::allocation_align_size_up(capacity * sizeof(oop)));
257 if (!rs.is_reserved()) {
258 warning("ConcurrentMark MarkStack allocation failure");
259 return false;
260 }
261 MemTracker::record_virtual_memory_type((address)rs.base(), mtGC);
262 if (!_virtual_space.initialize(rs, rs.size())) {
263 warning("ConcurrentMark MarkStack backing store failure");
264 // Release the virtual memory reserved for the marking stack
265 rs.release();
266 return false;
267 }
268 assert(_virtual_space.committed_size() == rs.size(),
269 "Didn't reserve backing store for all of ConcurrentMark stack?");
270 _base = (oop*) _virtual_space.low();
271 setEmpty();
272 _capacity = (jint) capacity;
273 _saved_index = -1;
274 _should_expand = false;
275 NOT_PRODUCT(_max_depth = 0);
276 return true;
277 }
278
279 void CMMarkStack::expand() {
280 // Called, during remark, if we've overflown the marking stack during marking.
281 assert(isEmpty(), "stack should been emptied while handling overflow");
282 assert(_capacity <= (jint) MarkStackSizeMax, "stack bigger than permitted");
283 // Clear expansion flag
284 _should_expand = false;
285 if (_capacity == (jint) MarkStackSizeMax) {
286 if (PrintGCDetails && Verbose) {
287 gclog_or_tty->print_cr(" (benign) Can't expand marking stack capacity, at max size limit");
288 }
289 return;
290 }
291 // Double capacity if possible
292 jint new_capacity = MIN2(_capacity*2, (jint) MarkStackSizeMax);
293 // Do not give up existing stack until we have managed to
294 // get the double capacity that we desired.
295 ReservedSpace rs(ReservedSpace::allocation_align_size_up(new_capacity *
296 sizeof(oop)));
297 if (rs.is_reserved()) {
298 // Release the backing store associated with old stack
299 _virtual_space.release();
300 // Reinitialize virtual space for new stack
301 if (!_virtual_space.initialize(rs, rs.size())) {
302 fatal("Not enough swap for expanded marking stack capacity");
303 }
304 _base = (oop*)(_virtual_space.low());
305 _index = 0;
306 _capacity = new_capacity;
307 } else {
308 if (PrintGCDetails && Verbose) {
309 // Failed to double capacity, continue;
310 gclog_or_tty->print(" (benign) Failed to expand marking stack capacity from "
311 SIZE_FORMAT"K to " SIZE_FORMAT"K",
312 _capacity / K, new_capacity / K);
313 }
314 }
315 }
316
317 void CMMarkStack::set_should_expand() {
318 // If we're resetting the marking state because of an
319 // marking stack overflow, record that we should, if
320 // possible, expand the stack.
321 _should_expand = _cm->has_overflown();
322 }
323
324 CMMarkStack::~CMMarkStack() {
325 if (_base != NULL) {
326 _base = NULL;
327 _virtual_space.release();
328 }
329 }
330
331 void CMMarkStack::par_push(oop ptr) {
332 while (true) {
333 if (isFull()) {
334 _overflow = true;
335 return;
336 }
337 // Otherwise...
338 jint index = _index;
339 jint next_index = index+1;
340 jint res = Atomic::cmpxchg(next_index, &_index, index);
341 if (res == index) {
342 _base[index] = ptr;
343 // Note that we don't maintain this atomically. We could, but it
344 // doesn't seem necessary.
345 NOT_PRODUCT(_max_depth = MAX2(_max_depth, next_index));
346 return;
347 }
348 // Otherwise, we need to try again.
349 }
350 }
351
352 void CMMarkStack::par_adjoin_arr(oop* ptr_arr, int n) {
353 while (true) {
354 if (isFull()) {
355 _overflow = true;
356 return;
357 }
358 // Otherwise...
359 jint index = _index;
360 jint next_index = index + n;
361 if (next_index > _capacity) {
362 _overflow = true;
363 return;
364 }
365 jint res = Atomic::cmpxchg(next_index, &_index, index);
366 if (res == index) {
367 for (int i = 0; i < n; i++) {
368 int ind = index + i;
369 assert(ind < _capacity, "By overflow test above.");
370 _base[ind] = ptr_arr[i];
371 }
372 NOT_PRODUCT(_max_depth = MAX2(_max_depth, next_index));
373 return;
374 }
375 // Otherwise, we need to try again.
376 }
377 }
378
379 void CMMarkStack::par_push_arr(oop* ptr_arr, int n) {
380 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
381 jint start = _index;
382 jint next_index = start + n;
383 if (next_index > _capacity) {
384 _overflow = true;
385 return;
386 }
387 // Otherwise.
388 _index = next_index;
389 for (int i = 0; i < n; i++) {
390 int ind = start + i;
391 assert(ind < _capacity, "By overflow test above.");
392 _base[ind] = ptr_arr[i];
393 }
394 NOT_PRODUCT(_max_depth = MAX2(_max_depth, next_index));
395 }
396
397 bool CMMarkStack::par_pop_arr(oop* ptr_arr, int max, int* n) {
398 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
399 jint index = _index;
400 if (index == 0) {
401 *n = 0;
402 return false;
403 } else {
404 int k = MIN2(max, index);
405 jint new_ind = index - k;
406 for (int j = 0; j < k; j++) {
407 ptr_arr[j] = _base[new_ind + j];
408 }
409 _index = new_ind;
410 *n = k;
411 return true;
412 }
413 }
414
415 template<class OopClosureClass>
416 bool CMMarkStack::drain(OopClosureClass* cl, CMBitMap* bm, bool yield_after) {
417 assert(!_drain_in_progress || !_drain_in_progress_yields || yield_after
418 || SafepointSynchronize::is_at_safepoint(),
419 "Drain recursion must be yield-safe.");
420 bool res = true;
421 debug_only(_drain_in_progress = true);
422 debug_only(_drain_in_progress_yields = yield_after);
423 while (!isEmpty()) {
424 oop newOop = pop();
425 assert(G1CollectedHeap::heap()->is_in_reserved(newOop), "Bad pop");
426 assert(newOop->is_oop(), "Expected an oop");
427 assert(bm == NULL || bm->isMarked((HeapWord*)newOop),
428 "only grey objects on this stack");
429 newOop->oop_iterate(cl);
430 if (yield_after && _cm->do_yield_check()) {
431 res = false;
432 break;
433 }
434 }
435 debug_only(_drain_in_progress = false);
436 return res;
437 }
438
439 void CMMarkStack::note_start_of_gc() {
440 assert(_saved_index == -1,
441 "note_start_of_gc()/end_of_gc() bracketed incorrectly");
442 _saved_index = _index;
443 }
444
445 void CMMarkStack::note_end_of_gc() {
446 // This is intentionally a guarantee, instead of an assert. If we
447 // accidentally add something to the mark stack during GC, it
448 // will be a correctness issue so it's better if we crash. we'll
449 // only check this once per GC anyway, so it won't be a performance
450 // issue in any way.
451 guarantee(_saved_index == _index,
452 err_msg("saved index: %d index: %d", _saved_index, _index));
453 _saved_index = -1;
454 }
455
456 void CMMarkStack::oops_do(OopClosure* f) {
457 assert(_saved_index == _index,
458 err_msg("saved index: %d index: %d", _saved_index, _index));
459 for (int i = 0; i < _index; i += 1) {
460 f->do_oop(&_base[i]);
461 }
462 }
463
464 CMRootRegions::CMRootRegions() :
465 _young_list(NULL), _cm(NULL), _scan_in_progress(false),
466 _should_abort(false), _next_survivor(NULL) { }
467
468 void CMRootRegions::init(G1CollectedHeap* g1h, ConcurrentMark* cm) {
469 _young_list = g1h->young_list();
470 _cm = cm;
471 }
472
473 void CMRootRegions::prepare_for_scan() {
474 assert(!scan_in_progress(), "pre-condition");
475
476 // Currently, only survivors can be root regions.
477 assert(_next_survivor == NULL, "pre-condition");
478 _next_survivor = _young_list->first_survivor_region();
479 _scan_in_progress = (_next_survivor != NULL);
480 _should_abort = false;
481 }
482
483 HeapRegion* CMRootRegions::claim_next() {
484 if (_should_abort) {
485 // If someone has set the should_abort flag, we return NULL to
486 // force the caller to bail out of their loop.
487 return NULL;
488 }
489
490 // Currently, only survivors can be root regions.
491 HeapRegion* res = _next_survivor;
492 if (res != NULL) {
493 MutexLockerEx x(RootRegionScan_lock, Mutex::_no_safepoint_check_flag);
494 // Read it again in case it changed while we were waiting for the lock.
495 res = _next_survivor;
496 if (res != NULL) {
497 if (res == _young_list->last_survivor_region()) {
498 // We just claimed the last survivor so store NULL to indicate
499 // that we're done.
500 _next_survivor = NULL;
501 } else {
502 _next_survivor = res->get_next_young_region();
503 }
504 } else {
505 // Someone else claimed the last survivor while we were trying
506 // to take the lock so nothing else to do.
507 }
508 }
509 assert(res == NULL || res->is_survivor(), "post-condition");
510
511 return res;
512 }
513
514 void CMRootRegions::scan_finished() {
515 assert(scan_in_progress(), "pre-condition");
516
517 // Currently, only survivors can be root regions.
518 if (!_should_abort) {
519 assert(_next_survivor == NULL, "we should have claimed all survivors");
520 }
521 _next_survivor = NULL;
522
523 {
524 MutexLockerEx x(RootRegionScan_lock, Mutex::_no_safepoint_check_flag);
525 _scan_in_progress = false;
526 RootRegionScan_lock->notify_all();
527 }
528 }
529
530 bool CMRootRegions::wait_until_scan_finished() {
531 if (!scan_in_progress()) return false;
532
533 {
534 MutexLockerEx x(RootRegionScan_lock, Mutex::_no_safepoint_check_flag);
535 while (scan_in_progress()) {
536 RootRegionScan_lock->wait(Mutex::_no_safepoint_check_flag);
537 }
538 }
539 return true;
540 }
541
542 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
543 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
544 #endif // _MSC_VER
545
546 uint ConcurrentMark::scale_parallel_threads(uint n_par_threads) {
547 return MAX2((n_par_threads + 2) / 4, 1U);
548 }
549
550 ConcurrentMark::ConcurrentMark(G1CollectedHeap* g1h, G1RegionToSpaceMapper* prev_bitmap_storage, G1RegionToSpaceMapper* next_bitmap_storage) :
551 _g1h(g1h),
552 _markBitMap1(),
553 _markBitMap2(),
554 _parallel_marking_threads(0),
555 _max_parallel_marking_threads(0),
556 _sleep_factor(0.0),
557 _marking_task_overhead(1.0),
558 _cleanup_sleep_factor(0.0),
559 _cleanup_task_overhead(1.0),
560 _cleanup_list("Cleanup List"),
561 _region_bm((BitMap::idx_t)(g1h->max_regions()), false /* in_resource_area*/),
562 _card_bm((g1h->reserved_region().byte_size() + CardTableModRefBS::card_size - 1) >>
563 CardTableModRefBS::card_shift,
564 false /* in_resource_area*/),
565
566 _prevMarkBitMap(&_markBitMap1),
567 _nextMarkBitMap(&_markBitMap2),
568
569 _markStack(this),
570 // _finger set in set_non_marking_state
571
572 _max_worker_id(MAX2((uint)ParallelGCThreads, 1U)),
573 // _active_tasks set in set_non_marking_state
574 // _tasks set inside the constructor
575 _task_queues(new CMTaskQueueSet((int) _max_worker_id)),
576 _terminator(ParallelTaskTerminator((int) _max_worker_id, _task_queues)),
577
578 _has_overflown(false),
579 _concurrent(false),
580 _has_aborted(false),
581 _aborted_gc_id(GCId::undefined()),
582 _restart_for_overflow(false),
583 _concurrent_marking_in_progress(false),
584
585 // _verbose_level set below
586
587 _init_times(),
588 _remark_times(), _remark_mark_times(), _remark_weak_ref_times(),
589 _cleanup_times(),
590 _total_counting_time(0.0),
591 _total_rs_scrub_time(0.0),
592
593 _parallel_workers(NULL),
594
595 _count_card_bitmaps(NULL),
596 _count_marked_bytes(NULL),
597 _completed_initialization(false) {
598 CMVerboseLevel verbose_level = (CMVerboseLevel) G1MarkingVerboseLevel;
599 if (verbose_level < no_verbose) {
600 verbose_level = no_verbose;
601 }
602 if (verbose_level > high_verbose) {
603 verbose_level = high_verbose;
604 }
605 _verbose_level = verbose_level;
606
607 if (verbose_low()) {
608 gclog_or_tty->print_cr("[global] init, heap start = "PTR_FORMAT", "
609 "heap end = " PTR_FORMAT, p2i(_heap_start), p2i(_heap_end));
610 }
611
612 _markBitMap1.initialize(g1h->reserved_region(), prev_bitmap_storage);
613 _markBitMap2.initialize(g1h->reserved_region(), next_bitmap_storage);
614
615 // Create & start a ConcurrentMark thread.
616 _cmThread = new ConcurrentMarkThread(this);
617 assert(cmThread() != NULL, "CM Thread should have been created");
618 assert(cmThread()->cm() != NULL, "CM Thread should refer to this cm");
619 if (_cmThread->osthread() == NULL) {
620 vm_shutdown_during_initialization("Could not create ConcurrentMarkThread");
621 }
622
623 assert(CGC_lock != NULL, "Where's the CGC_lock?");
624 assert(_markBitMap1.covers(g1h->reserved_region()), "_markBitMap1 inconsistency");
625 assert(_markBitMap2.covers(g1h->reserved_region()), "_markBitMap2 inconsistency");
626
627 SATBMarkQueueSet& satb_qs = JavaThread::satb_mark_queue_set();
628 satb_qs.set_buffer_size(G1SATBBufferSize);
629
630 _root_regions.init(_g1h, this);
631
632 if (ConcGCThreads > ParallelGCThreads) {
633 warning("Can't have more ConcGCThreads (" UINTX_FORMAT ") "
634 "than ParallelGCThreads (" UINTX_FORMAT ").",
635 ConcGCThreads, ParallelGCThreads);
636 return;
637 }
638 if (!FLAG_IS_DEFAULT(ConcGCThreads) && ConcGCThreads > 0) {
639 // Note: ConcGCThreads has precedence over G1MarkingOverheadPercent
640 // if both are set
641 _sleep_factor = 0.0;
642 _marking_task_overhead = 1.0;
643 } else if (G1MarkingOverheadPercent > 0) {
644 // We will calculate the number of parallel marking threads based
645 // on a target overhead with respect to the soft real-time goal
646 double marking_overhead = (double) G1MarkingOverheadPercent / 100.0;
647 double overall_cm_overhead =
648 (double) MaxGCPauseMillis * marking_overhead /
649 (double) GCPauseIntervalMillis;
650 double cpu_ratio = 1.0 / (double) os::processor_count();
651 double marking_thread_num = ceil(overall_cm_overhead / cpu_ratio);
652 double marking_task_overhead =
653 overall_cm_overhead / marking_thread_num *
654 (double) os::processor_count();
655 double sleep_factor =
656 (1.0 - marking_task_overhead) / marking_task_overhead;
657
658 FLAG_SET_ERGO(uintx, ConcGCThreads, (uint) marking_thread_num);
659 _sleep_factor = sleep_factor;
660 _marking_task_overhead = marking_task_overhead;
661 } else {
662 // Calculate the number of parallel marking threads by scaling
663 // the number of parallel GC threads.
664 uint marking_thread_num = scale_parallel_threads((uint) ParallelGCThreads);
665 FLAG_SET_ERGO(uintx, ConcGCThreads, marking_thread_num);
666 _sleep_factor = 0.0;
667 _marking_task_overhead = 1.0;
668 }
669
670 assert(ConcGCThreads > 0, "Should have been set");
671 _parallel_marking_threads = (uint) ConcGCThreads;
672 _max_parallel_marking_threads = _parallel_marking_threads;
673
674 if (parallel_marking_threads() > 1) {
675 _cleanup_task_overhead = 1.0;
676 } else {
677 _cleanup_task_overhead = marking_task_overhead();
678 }
679 _cleanup_sleep_factor =
680 (1.0 - cleanup_task_overhead()) / cleanup_task_overhead();
681
682 #if 0
683 gclog_or_tty->print_cr("Marking Threads %d", parallel_marking_threads());
684 gclog_or_tty->print_cr("CM Marking Task Overhead %1.4lf", marking_task_overhead());
685 gclog_or_tty->print_cr("CM Sleep Factor %1.4lf", sleep_factor());
686 gclog_or_tty->print_cr("CL Marking Task Overhead %1.4lf", cleanup_task_overhead());
687 gclog_or_tty->print_cr("CL Sleep Factor %1.4lf", cleanup_sleep_factor());
688 #endif
689
690 _parallel_workers = new FlexibleWorkGang("G1 Marker",
691 _max_parallel_marking_threads, false, true);
692 if (_parallel_workers == NULL) {
693 vm_exit_during_initialization("Failed necessary allocation.");
694 } else {
695 _parallel_workers->initialize_workers();
696 }
697
698 if (FLAG_IS_DEFAULT(MarkStackSize)) {
699 uintx mark_stack_size =
700 MIN2(MarkStackSizeMax,
701 MAX2(MarkStackSize, (uintx) (parallel_marking_threads() * TASKQUEUE_SIZE)));
702 // Verify that the calculated value for MarkStackSize is in range.
703 // It would be nice to use the private utility routine from Arguments.
704 if (!(mark_stack_size >= 1 && mark_stack_size <= MarkStackSizeMax)) {
705 warning("Invalid value calculated for MarkStackSize (" UINTX_FORMAT "): "
706 "must be between " UINTX_FORMAT " and " UINTX_FORMAT,
707 mark_stack_size, (uintx) 1, MarkStackSizeMax);
708 return;
709 }
710 FLAG_SET_ERGO(uintx, MarkStackSize, mark_stack_size);
711 } else {
712 // Verify MarkStackSize is in range.
713 if (FLAG_IS_CMDLINE(MarkStackSize)) {
714 if (FLAG_IS_DEFAULT(MarkStackSizeMax)) {
715 if (!(MarkStackSize >= 1 && MarkStackSize <= MarkStackSizeMax)) {
716 warning("Invalid value specified for MarkStackSize (" UINTX_FORMAT "): "
717 "must be between " UINTX_FORMAT " and " UINTX_FORMAT,
718 MarkStackSize, (uintx) 1, MarkStackSizeMax);
719 return;
720 }
721 } else if (FLAG_IS_CMDLINE(MarkStackSizeMax)) {
722 if (!(MarkStackSize >= 1 && MarkStackSize <= MarkStackSizeMax)) {
723 warning("Invalid value specified for MarkStackSize (" UINTX_FORMAT ")"
724 " or for MarkStackSizeMax (" UINTX_FORMAT ")",
725 MarkStackSize, MarkStackSizeMax);
726 return;
727 }
728 }
729 }
730 }
731
732 if (!_markStack.allocate(MarkStackSize)) {
733 warning("Failed to allocate CM marking stack");
734 return;
735 }
736
737 _tasks = NEW_C_HEAP_ARRAY(CMTask*, _max_worker_id, mtGC);
738 _accum_task_vtime = NEW_C_HEAP_ARRAY(double, _max_worker_id, mtGC);
739
740 _count_card_bitmaps = NEW_C_HEAP_ARRAY(BitMap, _max_worker_id, mtGC);
741 _count_marked_bytes = NEW_C_HEAP_ARRAY(size_t*, _max_worker_id, mtGC);
742
743 BitMap::idx_t card_bm_size = _card_bm.size();
744
745 // so that the assertion in MarkingTaskQueue::task_queue doesn't fail
746 _active_tasks = _max_worker_id;
747
748 size_t max_regions = (size_t) _g1h->max_regions();
749 for (uint i = 0; i < _max_worker_id; ++i) {
750 CMTaskQueue* task_queue = new CMTaskQueue();
751 task_queue->initialize();
752 _task_queues->register_queue(i, task_queue);
753
754 _count_card_bitmaps[i] = BitMap(card_bm_size, false);
755 _count_marked_bytes[i] = NEW_C_HEAP_ARRAY(size_t, max_regions, mtGC);
756
757 _tasks[i] = new CMTask(i, this,
758 _count_marked_bytes[i],
759 &_count_card_bitmaps[i],
760 task_queue, _task_queues);
761
762 _accum_task_vtime[i] = 0.0;
763 }
764
765 // Calculate the card number for the bottom of the heap. Used
766 // in biasing indexes into the accounting card bitmaps.
767 _heap_bottom_card_num =
768 intptr_t(uintptr_t(_g1h->reserved_region().start()) >>
769 CardTableModRefBS::card_shift);
770
771 // Clear all the liveness counting data
772 clear_all_count_data();
773
774 // so that the call below can read a sensible value
775 _heap_start = g1h->reserved_region().start();
776 set_non_marking_state();
777 _completed_initialization = true;
778 }
779
780 void ConcurrentMark::reset() {
781 // Starting values for these two. This should be called in a STW
782 // phase.
783 MemRegion reserved = _g1h->g1_reserved();
784 _heap_start = reserved.start();
785 _heap_end = reserved.end();
786
787 // Separated the asserts so that we know which one fires.
788 assert(_heap_start != NULL, "heap bounds should look ok");
789 assert(_heap_end != NULL, "heap bounds should look ok");
790 assert(_heap_start < _heap_end, "heap bounds should look ok");
791
792 // Reset all the marking data structures and any necessary flags
793 reset_marking_state();
794
795 if (verbose_low()) {
796 gclog_or_tty->print_cr("[global] resetting");
797 }
798
799 // We do reset all of them, since different phases will use
800 // different number of active threads. So, it's easiest to have all
801 // of them ready.
802 for (uint i = 0; i < _max_worker_id; ++i) {
803 _tasks[i]->reset(_nextMarkBitMap);
804 }
805
806 // we need this to make sure that the flag is on during the evac
807 // pause with initial mark piggy-backed
808 set_concurrent_marking_in_progress();
809 }
810
811
812 void ConcurrentMark::reset_marking_state(bool clear_overflow) {
813 _markStack.set_should_expand();
814 _markStack.setEmpty(); // Also clears the _markStack overflow flag
815 if (clear_overflow) {
816 clear_has_overflown();
817 } else {
818 assert(has_overflown(), "pre-condition");
819 }
820 _finger = _heap_start;
821
822 for (uint i = 0; i < _max_worker_id; ++i) {
823 CMTaskQueue* queue = _task_queues->queue(i);
824 queue->set_empty();
825 }
826 }
827
828 void ConcurrentMark::set_concurrency(uint active_tasks) {
829 assert(active_tasks <= _max_worker_id, "we should not have more");
830
831 _active_tasks = active_tasks;
832 // Need to update the three data structures below according to the
833 // number of active threads for this phase.
834 _terminator = ParallelTaskTerminator((int) active_tasks, _task_queues);
835 _first_overflow_barrier_sync.set_n_workers((int) active_tasks);
836 _second_overflow_barrier_sync.set_n_workers((int) active_tasks);
837 }
838
839 void ConcurrentMark::set_concurrency_and_phase(uint active_tasks, bool concurrent) {
840 set_concurrency(active_tasks);
841
842 _concurrent = concurrent;
843 // We propagate this to all tasks, not just the active ones.
844 for (uint i = 0; i < _max_worker_id; ++i)
845 _tasks[i]->set_concurrent(concurrent);
846
847 if (concurrent) {
848 set_concurrent_marking_in_progress();
849 } else {
850 // We currently assume that the concurrent flag has been set to
851 // false before we start remark. At this point we should also be
852 // in a STW phase.
853 assert(!concurrent_marking_in_progress(), "invariant");
854 assert(out_of_regions(),
855 err_msg("only way to get here: _finger: "PTR_FORMAT", _heap_end: "PTR_FORMAT,
856 p2i(_finger), p2i(_heap_end)));
857 }
858 }
859
860 void ConcurrentMark::set_non_marking_state() {
861 // We set the global marking state to some default values when we're
862 // not doing marking.
863 reset_marking_state();
864 _active_tasks = 0;
865 clear_concurrent_marking_in_progress();
866 }
867
868 ConcurrentMark::~ConcurrentMark() {
869 // The ConcurrentMark instance is never freed.
870 ShouldNotReachHere();
871 }
872
873 void ConcurrentMark::clearNextBitmap() {
874 G1CollectedHeap* g1h = G1CollectedHeap::heap();
875
876 // Make sure that the concurrent mark thread looks to still be in
877 // the current cycle.
878 guarantee(cmThread()->during_cycle(), "invariant");
879
880 // We are finishing up the current cycle by clearing the next
881 // marking bitmap and getting it ready for the next cycle. During
882 // this time no other cycle can start. So, let's make sure that this
883 // is the case.
884 guarantee(!g1h->mark_in_progress(), "invariant");
885
886 ClearBitmapHRClosure cl(this, _nextMarkBitMap, true /* may_yield */);
887 ParClearNextMarkBitmapTask task(&cl, parallel_marking_threads(), true);
888 _parallel_workers->run_task(&task);
889
890 // Clear the liveness counting data. If the marking has been aborted, the abort()
891 // call already did that.
892 if (cl.complete()) {
893 clear_all_count_data();
894 }
895
896 // Repeat the asserts from above.
897 guarantee(cmThread()->during_cycle(), "invariant");
898 guarantee(!g1h->mark_in_progress(), "invariant");
899 }
900
901 class CheckBitmapClearHRClosure : public HeapRegionClosure {
902 CMBitMap* _bitmap;
903 bool _error;
904 public:
905 CheckBitmapClearHRClosure(CMBitMap* bitmap) : _bitmap(bitmap) {
906 }
907
908 virtual bool doHeapRegion(HeapRegion* r) {
909 // This closure can be called concurrently to the mutator, so we must make sure
910 // that the result of the getNextMarkedWordAddress() call is compared to the
911 // value passed to it as limit to detect any found bits.
912 // We can use the region's orig_end() for the limit and the comparison value
913 // as it always contains the "real" end of the region that never changes and
914 // has no side effects.
915 // Due to the latter, there can also be no problem with the compiler generating
916 // reloads of the orig_end() call.
917 HeapWord* end = r->orig_end();
918 return _bitmap->getNextMarkedWordAddress(r->bottom(), end) != end;
919 }
920 };
921
922 bool ConcurrentMark::nextMarkBitmapIsClear() {
923 CheckBitmapClearHRClosure cl(_nextMarkBitMap);
924 _g1h->heap_region_iterate(&cl);
925 return cl.complete();
926 }
927
928 class NoteStartOfMarkHRClosure: public HeapRegionClosure {
929 public:
930 bool doHeapRegion(HeapRegion* r) {
931 if (!r->is_continues_humongous()) {
932 r->note_start_of_marking();
933 }
934 return false;
935 }
936 };
937
938 void ConcurrentMark::checkpointRootsInitialPre() {
939 G1CollectedHeap* g1h = G1CollectedHeap::heap();
940 G1CollectorPolicy* g1p = g1h->g1_policy();
941
942 _has_aborted = false;
943
944 #ifndef PRODUCT
945 if (G1PrintReachableAtInitialMark) {
946 print_reachable("at-cycle-start",
947 VerifyOption_G1UsePrevMarking, true /* all */);
948 }
949 #endif
950
951 // Initialize marking structures. This has to be done in a STW phase.
952 reset();
953
954 // For each region note start of marking.
955 NoteStartOfMarkHRClosure startcl;
956 g1h->heap_region_iterate(&startcl);
957 }
958
959
960 void ConcurrentMark::checkpointRootsInitialPost() {
961 G1CollectedHeap* g1h = G1CollectedHeap::heap();
962
963 // If we force an overflow during remark, the remark operation will
964 // actually abort and we'll restart concurrent marking. If we always
965 // force an overflow during remark we'll never actually complete the
966 // marking phase. So, we initialize this here, at the start of the
967 // cycle, so that at the remaining overflow number will decrease at
968 // every remark and we'll eventually not need to cause one.
969 force_overflow_stw()->init();
970
971 // Start Concurrent Marking weak-reference discovery.
972 ReferenceProcessor* rp = g1h->ref_processor_cm();
973 // enable ("weak") refs discovery
974 rp->enable_discovery();
975 rp->setup_policy(false); // snapshot the soft ref policy to be used in this cycle
976
977 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
978 // This is the start of the marking cycle, we're expected all
979 // threads to have SATB queues with active set to false.
980 satb_mq_set.set_active_all_threads(true, /* new active value */
981 false /* expected_active */);
982
983 _root_regions.prepare_for_scan();
984
985 // update_g1_committed() will be called at the end of an evac pause
986 // when marking is on. So, it's also called at the end of the
987 // initial-mark pause to update the heap end, if the heap expands
988 // during it. No need to call it here.
989 }
990
991 /*
992 * Notice that in the next two methods, we actually leave the STS
993 * during the barrier sync and join it immediately afterwards. If we
994 * do not do this, the following deadlock can occur: one thread could
995 * be in the barrier sync code, waiting for the other thread to also
996 * sync up, whereas another one could be trying to yield, while also
997 * waiting for the other threads to sync up too.
998 *
999 * Note, however, that this code is also used during remark and in
1000 * this case we should not attempt to leave / enter the STS, otherwise
1001 * we'll either hit an assert (debug / fastdebug) or deadlock
1002 * (product). So we should only leave / enter the STS if we are
1003 * operating concurrently.
1004 *
1005 * Because the thread that does the sync barrier has left the STS, it
1006 * is possible to be suspended for a Full GC or an evacuation pause
1007 * could occur. This is actually safe, since the entering the sync
1008 * barrier is one of the last things do_marking_step() does, and it
1009 * doesn't manipulate any data structures afterwards.
1010 */
1011
1012 void ConcurrentMark::enter_first_sync_barrier(uint worker_id) {
1013 if (verbose_low()) {
1014 gclog_or_tty->print_cr("[%u] entering first barrier", worker_id);
1015 }
1016
1017 if (concurrent()) {
1018 SuspendibleThreadSet::leave();
1019 }
1020
1021 bool barrier_aborted = !_first_overflow_barrier_sync.enter();
1022
1023 if (concurrent()) {
1024 SuspendibleThreadSet::join();
1025 }
1026 // at this point everyone should have synced up and not be doing any
1027 // more work
1028
1029 if (verbose_low()) {
1030 if (barrier_aborted) {
1031 gclog_or_tty->print_cr("[%u] aborted first barrier", worker_id);
1032 } else {
1033 gclog_or_tty->print_cr("[%u] leaving first barrier", worker_id);
1034 }
1035 }
1036
1037 if (barrier_aborted) {
1038 // If the barrier aborted we ignore the overflow condition and
1039 // just abort the whole marking phase as quickly as possible.
1040 return;
1041 }
1042
1043 // If we're executing the concurrent phase of marking, reset the marking
1044 // state; otherwise the marking state is reset after reference processing,
1045 // during the remark pause.
1046 // If we reset here as a result of an overflow during the remark we will
1047 // see assertion failures from any subsequent set_concurrency_and_phase()
1048 // calls.
1049 if (concurrent()) {
1050 // let the task associated with with worker 0 do this
1051 if (worker_id == 0) {
1052 // task 0 is responsible for clearing the global data structures
1053 // We should be here because of an overflow. During STW we should
1054 // not clear the overflow flag since we rely on it being true when
1055 // we exit this method to abort the pause and restart concurrent
1056 // marking.
1057 reset_marking_state(true /* clear_overflow */);
1058 force_overflow()->update();
1059
1060 if (G1Log::fine()) {
1061 gclog_or_tty->gclog_stamp(concurrent_gc_id());
1062 gclog_or_tty->print_cr("[GC concurrent-mark-reset-for-overflow]");
1063 }
1064 }
1065 }
1066
1067 // after this, each task should reset its own data structures then
1068 // then go into the second barrier
1069 }
1070
1071 void ConcurrentMark::enter_second_sync_barrier(uint worker_id) {
1072 if (verbose_low()) {
1073 gclog_or_tty->print_cr("[%u] entering second barrier", worker_id);
1074 }
1075
1076 if (concurrent()) {
1077 SuspendibleThreadSet::leave();
1078 }
1079
1080 bool barrier_aborted = !_second_overflow_barrier_sync.enter();
1081
1082 if (concurrent()) {
1083 SuspendibleThreadSet::join();
1084 }
1085 // at this point everything should be re-initialized and ready to go
1086
1087 if (verbose_low()) {
1088 if (barrier_aborted) {
1089 gclog_or_tty->print_cr("[%u] aborted second barrier", worker_id);
1090 } else {
1091 gclog_or_tty->print_cr("[%u] leaving second barrier", worker_id);
1092 }
1093 }
1094 }
1095
1096 #ifndef PRODUCT
1097 void ForceOverflowSettings::init() {
1098 _num_remaining = G1ConcMarkForceOverflow;
1099 _force = false;
1100 update();
1101 }
1102
1103 void ForceOverflowSettings::update() {
1104 if (_num_remaining > 0) {
1105 _num_remaining -= 1;
1106 _force = true;
1107 } else {
1108 _force = false;
1109 }
1110 }
1111
1112 bool ForceOverflowSettings::should_force() {
1113 if (_force) {
1114 _force = false;
1115 return true;
1116 } else {
1117 return false;
1118 }
1119 }
1120 #endif // !PRODUCT
1121
1122 class CMConcurrentMarkingTask: public AbstractGangTask {
1123 private:
1124 ConcurrentMark* _cm;
1125 ConcurrentMarkThread* _cmt;
1126
1127 public:
1128 void work(uint worker_id) {
1129 assert(Thread::current()->is_ConcurrentGC_thread(),
1130 "this should only be done by a conc GC thread");
1131 ResourceMark rm;
1132
1133 double start_vtime = os::elapsedVTime();
1134
1135 SuspendibleThreadSet::join();
1136
1137 assert(worker_id < _cm->active_tasks(), "invariant");
1138 CMTask* the_task = _cm->task(worker_id);
1139 the_task->record_start_time();
1140 if (!_cm->has_aborted()) {
1141 do {
1142 double start_vtime_sec = os::elapsedVTime();
1143 double mark_step_duration_ms = G1ConcMarkStepDurationMillis;
1144
1145 the_task->do_marking_step(mark_step_duration_ms,
1146 true /* do_termination */,
1147 false /* is_serial*/);
1148
1149 double end_vtime_sec = os::elapsedVTime();
1150 double elapsed_vtime_sec = end_vtime_sec - start_vtime_sec;
1151 _cm->clear_has_overflown();
1152
1153 _cm->do_yield_check(worker_id);
1154
1155 jlong sleep_time_ms;
1156 if (!_cm->has_aborted() && the_task->has_aborted()) {
1157 sleep_time_ms =
1158 (jlong) (elapsed_vtime_sec * _cm->sleep_factor() * 1000.0);
1159 SuspendibleThreadSet::leave();
1160 os::sleep(Thread::current(), sleep_time_ms, false);
1161 SuspendibleThreadSet::join();
1162 }
1163 } while (!_cm->has_aborted() && the_task->has_aborted());
1164 }
1165 the_task->record_end_time();
1166 guarantee(!the_task->has_aborted() || _cm->has_aborted(), "invariant");
1167
1168 SuspendibleThreadSet::leave();
1169
1170 double end_vtime = os::elapsedVTime();
1171 _cm->update_accum_task_vtime(worker_id, end_vtime - start_vtime);
1172 }
1173
1174 CMConcurrentMarkingTask(ConcurrentMark* cm,
1175 ConcurrentMarkThread* cmt) :
1176 AbstractGangTask("Concurrent Mark"), _cm(cm), _cmt(cmt) { }
1177
1178 ~CMConcurrentMarkingTask() { }
1179 };
1180
1181 // Calculates the number of active workers for a concurrent
1182 // phase.
1183 uint ConcurrentMark::calc_parallel_marking_threads() {
1184 uint n_conc_workers = 0;
1185 if (!UseDynamicNumberOfGCThreads ||
1186 (!FLAG_IS_DEFAULT(ConcGCThreads) &&
1187 !ForceDynamicNumberOfGCThreads)) {
1188 n_conc_workers = max_parallel_marking_threads();
1189 } else {
1190 n_conc_workers =
1191 AdaptiveSizePolicy::calc_default_active_workers(
1192 max_parallel_marking_threads(),
1193 1, /* Minimum workers */
1194 parallel_marking_threads(),
1195 Threads::number_of_non_daemon_threads());
1196 // Don't scale down "n_conc_workers" by scale_parallel_threads() because
1197 // that scaling has already gone into "_max_parallel_marking_threads".
1198 }
1199 assert(n_conc_workers > 0, "Always need at least 1");
1200 return n_conc_workers;
1201 }
1202
1203 void ConcurrentMark::scanRootRegion(HeapRegion* hr, uint worker_id) {
1204 // Currently, only survivors can be root regions.
1205 assert(hr->next_top_at_mark_start() == hr->bottom(), "invariant");
1206 G1RootRegionScanClosure cl(_g1h, this, worker_id);
1207
1208 const uintx interval = PrefetchScanIntervalInBytes;
1209 HeapWord* curr = hr->bottom();
1210 const HeapWord* end = hr->top();
1211 while (curr < end) {
1212 Prefetch::read(curr, interval);
1213 oop obj = oop(curr);
1214 int size = obj->oop_iterate(&cl);
1215 assert(size == obj->size(), "sanity");
1216 curr += size;
1217 }
1218 }
1219
1220 class CMRootRegionScanTask : public AbstractGangTask {
1221 private:
1222 ConcurrentMark* _cm;
1223
1224 public:
1225 CMRootRegionScanTask(ConcurrentMark* cm) :
1226 AbstractGangTask("Root Region Scan"), _cm(cm) { }
1227
1228 void work(uint worker_id) {
1229 assert(Thread::current()->is_ConcurrentGC_thread(),
1230 "this should only be done by a conc GC thread");
1231
1232 CMRootRegions* root_regions = _cm->root_regions();
1233 HeapRegion* hr = root_regions->claim_next();
1234 while (hr != NULL) {
1235 _cm->scanRootRegion(hr, worker_id);
1236 hr = root_regions->claim_next();
1237 }
1238 }
1239 };
1240
1241 void ConcurrentMark::scanRootRegions() {
1242 // Start of concurrent marking.
1243 ClassLoaderDataGraph::clear_claimed_marks();
1244
1245 // scan_in_progress() will have been set to true only if there was
1246 // at least one root region to scan. So, if it's false, we
1247 // should not attempt to do any further work.
1248 if (root_regions()->scan_in_progress()) {
1249 _parallel_marking_threads = calc_parallel_marking_threads();
1250 assert(parallel_marking_threads() <= max_parallel_marking_threads(),
1251 "Maximum number of marking threads exceeded");
1252 uint active_workers = MAX2(1U, parallel_marking_threads());
1253
1254 CMRootRegionScanTask task(this);
1255 _parallel_workers->set_active_workers(active_workers);
1256 _parallel_workers->run_task(&task);
1257
1258 // It's possible that has_aborted() is true here without actually
1259 // aborting the survivor scan earlier. This is OK as it's
1260 // mainly used for sanity checking.
1261 root_regions()->scan_finished();
1262 }
1263 }
1264
1265 void ConcurrentMark::markFromRoots() {
1266 // we might be tempted to assert that:
1267 // assert(asynch == !SafepointSynchronize::is_at_safepoint(),
1268 // "inconsistent argument?");
1269 // However that wouldn't be right, because it's possible that
1270 // a safepoint is indeed in progress as a younger generation
1271 // stop-the-world GC happens even as we mark in this generation.
1272
1273 _restart_for_overflow = false;
1274 force_overflow_conc()->init();
1275
1276 // _g1h has _n_par_threads
1277 _parallel_marking_threads = calc_parallel_marking_threads();
1278 assert(parallel_marking_threads() <= max_parallel_marking_threads(),
1279 "Maximum number of marking threads exceeded");
1280
1281 uint active_workers = MAX2(1U, parallel_marking_threads());
1282
1283 // Parallel task terminator is set in "set_concurrency_and_phase()"
1284 set_concurrency_and_phase(active_workers, true /* concurrent */);
1285
1286 CMConcurrentMarkingTask markingTask(this, cmThread());
1287 _parallel_workers->set_active_workers(active_workers);
1288 // Don't set _n_par_threads because it affects MT in process_roots()
1289 // and the decisions on that MT processing is made elsewhere.
1290 assert(_parallel_workers->active_workers() > 0, "Should have been set");
1291 _parallel_workers->run_task(&markingTask);
1292 print_stats();
1293 }
1294
1295 // Helper class to get rid of some boilerplate code.
1296 class G1CMTraceTime : public GCTraceTime {
1297 static bool doit_and_prepend(bool doit) {
1298 if (doit) {
1299 gclog_or_tty->put(' ');
1300 }
1301 return doit;
1302 }
1303
1304 public:
1305 G1CMTraceTime(const char* title, bool doit)
1306 : GCTraceTime(title, doit_and_prepend(doit), false, G1CollectedHeap::heap()->gc_timer_cm(),
1307 G1CollectedHeap::heap()->concurrent_mark()->concurrent_gc_id()) {
1308 }
1309 };
1310
1311 void ConcurrentMark::checkpointRootsFinal(bool clear_all_soft_refs) {
1312 // world is stopped at this checkpoint
1313 assert(SafepointSynchronize::is_at_safepoint(),
1314 "world should be stopped");
1315
1316 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1317
1318 // If a full collection has happened, we shouldn't do this.
1319 if (has_aborted()) {
1320 g1h->set_marking_complete(); // So bitmap clearing isn't confused
1321 return;
1322 }
1323
1324 SvcGCMarker sgcm(SvcGCMarker::OTHER);
1325
1326 if (VerifyDuringGC) {
1327 HandleMark hm; // handle scope
1328 Universe::heap()->prepare_for_verify();
1329 Universe::verify(VerifyOption_G1UsePrevMarking,
1330 " VerifyDuringGC:(before)");
1331 }
1332 g1h->check_bitmaps("Remark Start");
1333
1334 G1CollectorPolicy* g1p = g1h->g1_policy();
1335 g1p->record_concurrent_mark_remark_start();
1336
1337 double start = os::elapsedTime();
1338
1339 checkpointRootsFinalWork();
1340
1341 double mark_work_end = os::elapsedTime();
1342
1343 weakRefsWork(clear_all_soft_refs);
1344
1345 if (has_overflown()) {
1346 // Oops. We overflowed. Restart concurrent marking.
1347 _restart_for_overflow = true;
1348 if (G1TraceMarkStackOverflow) {
1349 gclog_or_tty->print_cr("\nRemark led to restart for overflow.");
1350 }
1351
1352 // Verify the heap w.r.t. the previous marking bitmap.
1353 if (VerifyDuringGC) {
1354 HandleMark hm; // handle scope
1355 Universe::heap()->prepare_for_verify();
1356 Universe::verify(VerifyOption_G1UsePrevMarking,
1357 " VerifyDuringGC:(overflow)");
1358 }
1359
1360 // Clear the marking state because we will be restarting
1361 // marking due to overflowing the global mark stack.
1362 reset_marking_state();
1363 } else {
1364 {
1365 G1CMTraceTime trace("GC aggregate-data", G1Log::finer());
1366
1367 // Aggregate the per-task counting data that we have accumulated
1368 // while marking.
1369 aggregate_count_data();
1370 }
1371
1372 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
1373 // We're done with marking.
1374 // This is the end of the marking cycle, we're expected all
1375 // threads to have SATB queues with active set to true.
1376 satb_mq_set.set_active_all_threads(false, /* new active value */
1377 true /* expected_active */);
1378
1379 if (VerifyDuringGC) {
1380 HandleMark hm; // handle scope
1381 Universe::heap()->prepare_for_verify();
1382 Universe::verify(VerifyOption_G1UseNextMarking,
1383 " VerifyDuringGC:(after)");
1384 }
1385 g1h->check_bitmaps("Remark End");
1386 assert(!restart_for_overflow(), "sanity");
1387 // Completely reset the marking state since marking completed
1388 set_non_marking_state();
1389 }
1390
1391 // Expand the marking stack, if we have to and if we can.
1392 if (_markStack.should_expand()) {
1393 _markStack.expand();
1394 }
1395
1396 // Statistics
1397 double now = os::elapsedTime();
1398 _remark_mark_times.add((mark_work_end - start) * 1000.0);
1399 _remark_weak_ref_times.add((now - mark_work_end) * 1000.0);
1400 _remark_times.add((now - start) * 1000.0);
1401
1402 g1p->record_concurrent_mark_remark_end();
1403
1404 G1CMIsAliveClosure is_alive(g1h);
1405 g1h->gc_tracer_cm()->report_object_count_after_gc(&is_alive);
1406 }
1407
1408 // Base class of the closures that finalize and verify the
1409 // liveness counting data.
1410 class CMCountDataClosureBase: public HeapRegionClosure {
1411 protected:
1412 G1CollectedHeap* _g1h;
1413 ConcurrentMark* _cm;
1414 CardTableModRefBS* _ct_bs;
1415
1416 BitMap* _region_bm;
1417 BitMap* _card_bm;
1418
1419 // Takes a region that's not empty (i.e., it has at least one
1420 // live object in it and sets its corresponding bit on the region
1421 // bitmap to 1. If the region is "starts humongous" it will also set
1422 // to 1 the bits on the region bitmap that correspond to its
1423 // associated "continues humongous" regions.
1424 void set_bit_for_region(HeapRegion* hr) {
1425 assert(!hr->is_continues_humongous(), "should have filtered those out");
1426
1427 BitMap::idx_t index = (BitMap::idx_t) hr->hrm_index();
1428 if (!hr->is_starts_humongous()) {
1429 // Normal (non-humongous) case: just set the bit.
1430 _region_bm->par_at_put(index, true);
1431 } else {
1432 // Starts humongous case: calculate how many regions are part of
1433 // this humongous region and then set the bit range.
1434 BitMap::idx_t end_index = (BitMap::idx_t) hr->last_hc_index();
1435 _region_bm->par_at_put_range(index, end_index, true);
1436 }
1437 }
1438
1439 public:
1440 CMCountDataClosureBase(G1CollectedHeap* g1h,
1441 BitMap* region_bm, BitMap* card_bm):
1442 _g1h(g1h), _cm(g1h->concurrent_mark()),
1443 _ct_bs(barrier_set_cast<CardTableModRefBS>(g1h->barrier_set())),
1444 _region_bm(region_bm), _card_bm(card_bm) { }
1445 };
1446
1447 // Closure that calculates the # live objects per region. Used
1448 // for verification purposes during the cleanup pause.
1449 class CalcLiveObjectsClosure: public CMCountDataClosureBase {
1450 CMBitMapRO* _bm;
1451 size_t _region_marked_bytes;
1452
1453 public:
1454 CalcLiveObjectsClosure(CMBitMapRO *bm, G1CollectedHeap* g1h,
1455 BitMap* region_bm, BitMap* card_bm) :
1456 CMCountDataClosureBase(g1h, region_bm, card_bm),
1457 _bm(bm), _region_marked_bytes(0) { }
1458
1459 bool doHeapRegion(HeapRegion* hr) {
1460
1461 if (hr->is_continues_humongous()) {
1462 // We will ignore these here and process them when their
1463 // associated "starts humongous" region is processed (see
1464 // set_bit_for_heap_region()). Note that we cannot rely on their
1465 // associated "starts humongous" region to have their bit set to
1466 // 1 since, due to the region chunking in the parallel region
1467 // iteration, a "continues humongous" region might be visited
1468 // before its associated "starts humongous".
1469 return false;
1470 }
1471
1472 HeapWord* ntams = hr->next_top_at_mark_start();
1473 HeapWord* start = hr->bottom();
1474
1475 assert(start <= hr->end() && start <= ntams && ntams <= hr->end(),
1476 err_msg("Preconditions not met - "
1477 "start: "PTR_FORMAT", ntams: "PTR_FORMAT", end: "PTR_FORMAT,
1478 p2i(start), p2i(ntams), p2i(hr->end())));
1479
1480 // Find the first marked object at or after "start".
1481 start = _bm->getNextMarkedWordAddress(start, ntams);
1482
1483 size_t marked_bytes = 0;
1484
1485 while (start < ntams) {
1486 oop obj = oop(start);
1487 int obj_sz = obj->size();
1488 HeapWord* obj_end = start + obj_sz;
1489
1490 BitMap::idx_t start_idx = _cm->card_bitmap_index_for(start);
1491 BitMap::idx_t end_idx = _cm->card_bitmap_index_for(obj_end);
1492
1493 // Note: if we're looking at the last region in heap - obj_end
1494 // could be actually just beyond the end of the heap; end_idx
1495 // will then correspond to a (non-existent) card that is also
1496 // just beyond the heap.
1497 if (_g1h->is_in_g1_reserved(obj_end) && !_ct_bs->is_card_aligned(obj_end)) {
1498 // end of object is not card aligned - increment to cover
1499 // all the cards spanned by the object
1500 end_idx += 1;
1501 }
1502
1503 // Set the bits in the card BM for the cards spanned by this object.
1504 _cm->set_card_bitmap_range(_card_bm, start_idx, end_idx, true /* is_par */);
1505
1506 // Add the size of this object to the number of marked bytes.
1507 marked_bytes += (size_t)obj_sz * HeapWordSize;
1508
1509 // Find the next marked object after this one.
1510 start = _bm->getNextMarkedWordAddress(obj_end, ntams);
1511 }
1512
1513 // Mark the allocated-since-marking portion...
1514 HeapWord* top = hr->top();
1515 if (ntams < top) {
1516 BitMap::idx_t start_idx = _cm->card_bitmap_index_for(ntams);
1517 BitMap::idx_t end_idx = _cm->card_bitmap_index_for(top);
1518
1519 // Note: if we're looking at the last region in heap - top
1520 // could be actually just beyond the end of the heap; end_idx
1521 // will then correspond to a (non-existent) card that is also
1522 // just beyond the heap.
1523 if (_g1h->is_in_g1_reserved(top) && !_ct_bs->is_card_aligned(top)) {
1524 // end of object is not card aligned - increment to cover
1525 // all the cards spanned by the object
1526 end_idx += 1;
1527 }
1528 _cm->set_card_bitmap_range(_card_bm, start_idx, end_idx, true /* is_par */);
1529
1530 // This definitely means the region has live objects.
1531 set_bit_for_region(hr);
1532 }
1533
1534 // Update the live region bitmap.
1535 if (marked_bytes > 0) {
1536 set_bit_for_region(hr);
1537 }
1538
1539 // Set the marked bytes for the current region so that
1540 // it can be queried by a calling verification routine
1541 _region_marked_bytes = marked_bytes;
1542
1543 return false;
1544 }
1545
1546 size_t region_marked_bytes() const { return _region_marked_bytes; }
1547 };
1548
1549 // Heap region closure used for verifying the counting data
1550 // that was accumulated concurrently and aggregated during
1551 // the remark pause. This closure is applied to the heap
1552 // regions during the STW cleanup pause.
1553
1554 class VerifyLiveObjectDataHRClosure: public HeapRegionClosure {
1555 G1CollectedHeap* _g1h;
1556 ConcurrentMark* _cm;
1557 CalcLiveObjectsClosure _calc_cl;
1558 BitMap* _region_bm; // Region BM to be verified
1559 BitMap* _card_bm; // Card BM to be verified
1560 bool _verbose; // verbose output?
1561
1562 BitMap* _exp_region_bm; // Expected Region BM values
1563 BitMap* _exp_card_bm; // Expected card BM values
1564
1565 int _failures;
1566
1567 public:
1568 VerifyLiveObjectDataHRClosure(G1CollectedHeap* g1h,
1569 BitMap* region_bm,
1570 BitMap* card_bm,
1571 BitMap* exp_region_bm,
1572 BitMap* exp_card_bm,
1573 bool verbose) :
1574 _g1h(g1h), _cm(g1h->concurrent_mark()),
1575 _calc_cl(_cm->nextMarkBitMap(), g1h, exp_region_bm, exp_card_bm),
1576 _region_bm(region_bm), _card_bm(card_bm), _verbose(verbose),
1577 _exp_region_bm(exp_region_bm), _exp_card_bm(exp_card_bm),
1578 _failures(0) { }
1579
1580 int failures() const { return _failures; }
1581
1582 bool doHeapRegion(HeapRegion* hr) {
1583 if (hr->is_continues_humongous()) {
1584 // We will ignore these here and process them when their
1585 // associated "starts humongous" region is processed (see
1586 // set_bit_for_heap_region()). Note that we cannot rely on their
1587 // associated "starts humongous" region to have their bit set to
1588 // 1 since, due to the region chunking in the parallel region
1589 // iteration, a "continues humongous" region might be visited
1590 // before its associated "starts humongous".
1591 return false;
1592 }
1593
1594 int failures = 0;
1595
1596 // Call the CalcLiveObjectsClosure to walk the marking bitmap for
1597 // this region and set the corresponding bits in the expected region
1598 // and card bitmaps.
1599 bool res = _calc_cl.doHeapRegion(hr);
1600 assert(res == false, "should be continuing");
1601
1602 MutexLockerEx x((_verbose ? ParGCRareEvent_lock : NULL),
1603 Mutex::_no_safepoint_check_flag);
1604
1605 // Verify the marked bytes for this region.
1606 size_t exp_marked_bytes = _calc_cl.region_marked_bytes();
1607 size_t act_marked_bytes = hr->next_marked_bytes();
1608
1609 // We're not OK if expected marked bytes > actual marked bytes. It means
1610 // we have missed accounting some objects during the actual marking.
1611 if (exp_marked_bytes > act_marked_bytes) {
1612 if (_verbose) {
1613 gclog_or_tty->print_cr("Region %u: marked bytes mismatch: "
1614 "expected: " SIZE_FORMAT ", actual: " SIZE_FORMAT,
1615 hr->hrm_index(), exp_marked_bytes, act_marked_bytes);
1616 }
1617 failures += 1;
1618 }
1619
1620 // Verify the bit, for this region, in the actual and expected
1621 // (which was just calculated) region bit maps.
1622 // We're not OK if the bit in the calculated expected region
1623 // bitmap is set and the bit in the actual region bitmap is not.
1624 BitMap::idx_t index = (BitMap::idx_t) hr->hrm_index();
1625
1626 bool expected = _exp_region_bm->at(index);
1627 bool actual = _region_bm->at(index);
1628 if (expected && !actual) {
1629 if (_verbose) {
1630 gclog_or_tty->print_cr("Region %u: region bitmap mismatch: "
1631 "expected: %s, actual: %s",
1632 hr->hrm_index(),
1633 BOOL_TO_STR(expected), BOOL_TO_STR(actual));
1634 }
1635 failures += 1;
1636 }
1637
1638 // Verify that the card bit maps for the cards spanned by the current
1639 // region match. We have an error if we have a set bit in the expected
1640 // bit map and the corresponding bit in the actual bitmap is not set.
1641
1642 BitMap::idx_t start_idx = _cm->card_bitmap_index_for(hr->bottom());
1643 BitMap::idx_t end_idx = _cm->card_bitmap_index_for(hr->top());
1644
1645 for (BitMap::idx_t i = start_idx; i < end_idx; i+=1) {
1646 expected = _exp_card_bm->at(i);
1647 actual = _card_bm->at(i);
1648
1649 if (expected && !actual) {
1650 if (_verbose) {
1651 gclog_or_tty->print_cr("Region %u: card bitmap mismatch at " SIZE_FORMAT ": "
1652 "expected: %s, actual: %s",
1653 hr->hrm_index(), i,
1654 BOOL_TO_STR(expected), BOOL_TO_STR(actual));
1655 }
1656 failures += 1;
1657 }
1658 }
1659
1660 if (failures > 0 && _verbose) {
1661 gclog_or_tty->print_cr("Region " HR_FORMAT ", ntams: " PTR_FORMAT ", "
1662 "marked_bytes: calc/actual " SIZE_FORMAT "/" SIZE_FORMAT,
1663 HR_FORMAT_PARAMS(hr), p2i(hr->next_top_at_mark_start()),
1664 _calc_cl.region_marked_bytes(), hr->next_marked_bytes());
1665 }
1666
1667 _failures += failures;
1668
1669 // We could stop iteration over the heap when we
1670 // find the first violating region by returning true.
1671 return false;
1672 }
1673 };
1674
1675 class G1ParVerifyFinalCountTask: public AbstractGangTask {
1676 protected:
1677 G1CollectedHeap* _g1h;
1678 ConcurrentMark* _cm;
1679 BitMap* _actual_region_bm;
1680 BitMap* _actual_card_bm;
1681
1682 uint _n_workers;
1683
1684 BitMap* _expected_region_bm;
1685 BitMap* _expected_card_bm;
1686
1687 int _failures;
1688 bool _verbose;
1689
1690 HeapRegionClaimer _hrclaimer;
1691
1692 public:
1693 G1ParVerifyFinalCountTask(G1CollectedHeap* g1h,
1694 BitMap* region_bm, BitMap* card_bm,
1695 BitMap* expected_region_bm, BitMap* expected_card_bm)
1696 : AbstractGangTask("G1 verify final counting"),
1697 _g1h(g1h), _cm(_g1h->concurrent_mark()),
1698 _actual_region_bm(region_bm), _actual_card_bm(card_bm),
1699 _expected_region_bm(expected_region_bm), _expected_card_bm(expected_card_bm),
1700 _failures(0), _verbose(false),
1701 _n_workers(_g1h->workers()->active_workers()), _hrclaimer(_n_workers) {
1702 assert(VerifyDuringGC, "don't call this otherwise");
1703 assert(_expected_card_bm->size() == _actual_card_bm->size(), "sanity");
1704 assert(_expected_region_bm->size() == _actual_region_bm->size(), "sanity");
1705
1706 _verbose = _cm->verbose_medium();
1707 }
1708
1709 void work(uint worker_id) {
1710 assert(worker_id < _n_workers, "invariant");
1711
1712 VerifyLiveObjectDataHRClosure verify_cl(_g1h,
1713 _actual_region_bm, _actual_card_bm,
1714 _expected_region_bm,
1715 _expected_card_bm,
1716 _verbose);
1717
1718 _g1h->heap_region_par_iterate(&verify_cl, worker_id, &_hrclaimer);
1719
1720 Atomic::add(verify_cl.failures(), &_failures);
1721 }
1722
1723 int failures() const { return _failures; }
1724 };
1725
1726 // Closure that finalizes the liveness counting data.
1727 // Used during the cleanup pause.
1728 // Sets the bits corresponding to the interval [NTAMS, top]
1729 // (which contains the implicitly live objects) in the
1730 // card liveness bitmap. Also sets the bit for each region,
1731 // containing live data, in the region liveness bitmap.
1732
1733 class FinalCountDataUpdateClosure: public CMCountDataClosureBase {
1734 public:
1735 FinalCountDataUpdateClosure(G1CollectedHeap* g1h,
1736 BitMap* region_bm,
1737 BitMap* card_bm) :
1738 CMCountDataClosureBase(g1h, region_bm, card_bm) { }
1739
1740 bool doHeapRegion(HeapRegion* hr) {
1741
1742 if (hr->is_continues_humongous()) {
1743 // We will ignore these here and process them when their
1744 // associated "starts humongous" region is processed (see
1745 // set_bit_for_heap_region()). Note that we cannot rely on their
1746 // associated "starts humongous" region to have their bit set to
1747 // 1 since, due to the region chunking in the parallel region
1748 // iteration, a "continues humongous" region might be visited
1749 // before its associated "starts humongous".
1750 return false;
1751 }
1752
1753 HeapWord* ntams = hr->next_top_at_mark_start();
1754 HeapWord* top = hr->top();
1755
1756 assert(hr->bottom() <= ntams && ntams <= hr->end(), "Preconditions.");
1757
1758 // Mark the allocated-since-marking portion...
1759 if (ntams < top) {
1760 // This definitely means the region has live objects.
1761 set_bit_for_region(hr);
1762
1763 // Now set the bits in the card bitmap for [ntams, top)
1764 BitMap::idx_t start_idx = _cm->card_bitmap_index_for(ntams);
1765 BitMap::idx_t end_idx = _cm->card_bitmap_index_for(top);
1766
1767 // Note: if we're looking at the last region in heap - top
1768 // could be actually just beyond the end of the heap; end_idx
1769 // will then correspond to a (non-existent) card that is also
1770 // just beyond the heap.
1771 if (_g1h->is_in_g1_reserved(top) && !_ct_bs->is_card_aligned(top)) {
1772 // end of object is not card aligned - increment to cover
1773 // all the cards spanned by the object
1774 end_idx += 1;
1775 }
1776
1777 assert(end_idx <= _card_bm->size(),
1778 err_msg("oob: end_idx= "SIZE_FORMAT", bitmap size= "SIZE_FORMAT,
1779 end_idx, _card_bm->size()));
1780 assert(start_idx < _card_bm->size(),
1781 err_msg("oob: start_idx= "SIZE_FORMAT", bitmap size= "SIZE_FORMAT,
1782 start_idx, _card_bm->size()));
1783
1784 _cm->set_card_bitmap_range(_card_bm, start_idx, end_idx, true /* is_par */);
1785 }
1786
1787 // Set the bit for the region if it contains live data
1788 if (hr->next_marked_bytes() > 0) {
1789 set_bit_for_region(hr);
1790 }
1791
1792 return false;
1793 }
1794 };
1795
1796 class G1ParFinalCountTask: public AbstractGangTask {
1797 protected:
1798 G1CollectedHeap* _g1h;
1799 ConcurrentMark* _cm;
1800 BitMap* _actual_region_bm;
1801 BitMap* _actual_card_bm;
1802
1803 uint _n_workers;
1804 HeapRegionClaimer _hrclaimer;
1805
1806 public:
1807 G1ParFinalCountTask(G1CollectedHeap* g1h, BitMap* region_bm, BitMap* card_bm)
1808 : AbstractGangTask("G1 final counting"),
1809 _g1h(g1h), _cm(_g1h->concurrent_mark()),
1810 _actual_region_bm(region_bm), _actual_card_bm(card_bm),
1811 _n_workers(_g1h->workers()->active_workers()), _hrclaimer(_n_workers) {
1812 }
1813
1814 void work(uint worker_id) {
1815 assert(worker_id < _n_workers, "invariant");
1816
1817 FinalCountDataUpdateClosure final_update_cl(_g1h,
1818 _actual_region_bm,
1819 _actual_card_bm);
1820
1821 _g1h->heap_region_par_iterate(&final_update_cl, worker_id, &_hrclaimer);
1822 }
1823 };
1824
1825 class G1ParNoteEndTask;
1826
1827 class G1NoteEndOfConcMarkClosure : public HeapRegionClosure {
1828 G1CollectedHeap* _g1;
1829 size_t _max_live_bytes;
1830 uint _regions_claimed;
1831 size_t _freed_bytes;
1832 FreeRegionList* _local_cleanup_list;
1833 HeapRegionSetCount _old_regions_removed;
1834 HeapRegionSetCount _humongous_regions_removed;
1835 HRRSCleanupTask* _hrrs_cleanup_task;
1836 double _claimed_region_time;
1837 double _max_region_time;
1838
1839 public:
1840 G1NoteEndOfConcMarkClosure(G1CollectedHeap* g1,
1841 FreeRegionList* local_cleanup_list,
1842 HRRSCleanupTask* hrrs_cleanup_task) :
1843 _g1(g1),
1844 _max_live_bytes(0), _regions_claimed(0),
1845 _freed_bytes(0),
1846 _claimed_region_time(0.0), _max_region_time(0.0),
1847 _local_cleanup_list(local_cleanup_list),
1848 _old_regions_removed(),
1849 _humongous_regions_removed(),
1850 _hrrs_cleanup_task(hrrs_cleanup_task) { }
1851
1852 size_t freed_bytes() { return _freed_bytes; }
1853 const HeapRegionSetCount& old_regions_removed() { return _old_regions_removed; }
1854 const HeapRegionSetCount& humongous_regions_removed() { return _humongous_regions_removed; }
1855
1856 bool doHeapRegion(HeapRegion *hr) {
1857 if (hr->is_continues_humongous()) {
1858 return false;
1859 }
1860 // We use a claim value of zero here because all regions
1861 // were claimed with value 1 in the FinalCount task.
1862 _g1->reset_gc_time_stamps(hr);
1863 double start = os::elapsedTime();
1864 _regions_claimed++;
1865 hr->note_end_of_marking();
1866 _max_live_bytes += hr->max_live_bytes();
1867
1868 if (hr->used() > 0 && hr->max_live_bytes() == 0 && !hr->is_young()) {
1869 _freed_bytes += hr->used();
1870 hr->set_containing_set(NULL);
1871 if (hr->is_humongous()) {
1872 assert(hr->is_starts_humongous(), "we should only see starts humongous");
1873 _humongous_regions_removed.increment(1u, hr->capacity());
1874 _g1->free_humongous_region(hr, _local_cleanup_list, true);
1875 } else {
1876 _old_regions_removed.increment(1u, hr->capacity());
1877 _g1->free_region(hr, _local_cleanup_list, true);
1878 }
1879 } else {
1880 hr->rem_set()->do_cleanup_work(_hrrs_cleanup_task);
1881 }
1882
1883 double region_time = (os::elapsedTime() - start);
1884 _claimed_region_time += region_time;
1885 if (region_time > _max_region_time) {
1886 _max_region_time = region_time;
1887 }
1888 return false;
1889 }
1890
1891 size_t max_live_bytes() { return _max_live_bytes; }
1892 uint regions_claimed() { return _regions_claimed; }
1893 double claimed_region_time_sec() { return _claimed_region_time; }
1894 double max_region_time_sec() { return _max_region_time; }
1895 };
1896
1897 class G1ParNoteEndTask: public AbstractGangTask {
1898 friend class G1NoteEndOfConcMarkClosure;
1899
1900 protected:
1901 G1CollectedHeap* _g1h;
1902 size_t _max_live_bytes;
1903 size_t _freed_bytes;
1904 FreeRegionList* _cleanup_list;
1905 HeapRegionClaimer _hrclaimer;
1906
1907 public:
1908 G1ParNoteEndTask(G1CollectedHeap* g1h, FreeRegionList* cleanup_list, uint n_workers) :
1909 AbstractGangTask("G1 note end"), _g1h(g1h), _max_live_bytes(0), _freed_bytes(0), _cleanup_list(cleanup_list), _hrclaimer(n_workers) {
1910 }
1911
1912 void work(uint worker_id) {
1913 FreeRegionList local_cleanup_list("Local Cleanup List");
1914 HRRSCleanupTask hrrs_cleanup_task;
1915 G1NoteEndOfConcMarkClosure g1_note_end(_g1h, &local_cleanup_list,
1916 &hrrs_cleanup_task);
1917 _g1h->heap_region_par_iterate(&g1_note_end, worker_id, &_hrclaimer);
1918 assert(g1_note_end.complete(), "Shouldn't have yielded!");
1919
1920 // Now update the lists
1921 _g1h->remove_from_old_sets(g1_note_end.old_regions_removed(), g1_note_end.humongous_regions_removed());
1922 {
1923 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
1924 _g1h->decrement_summary_bytes(g1_note_end.freed_bytes());
1925 _max_live_bytes += g1_note_end.max_live_bytes();
1926 _freed_bytes += g1_note_end.freed_bytes();
1927
1928 // If we iterate over the global cleanup list at the end of
1929 // cleanup to do this printing we will not guarantee to only
1930 // generate output for the newly-reclaimed regions (the list
1931 // might not be empty at the beginning of cleanup; we might
1932 // still be working on its previous contents). So we do the
1933 // printing here, before we append the new regions to the global
1934 // cleanup list.
1935
1936 G1HRPrinter* hr_printer = _g1h->hr_printer();
1937 if (hr_printer->is_active()) {
1938 FreeRegionListIterator iter(&local_cleanup_list);
1939 while (iter.more_available()) {
1940 HeapRegion* hr = iter.get_next();
1941 hr_printer->cleanup(hr);
1942 }
1943 }
1944
1945 _cleanup_list->add_ordered(&local_cleanup_list);
1946 assert(local_cleanup_list.is_empty(), "post-condition");
1947
1948 HeapRegionRemSet::finish_cleanup_task(&hrrs_cleanup_task);
1949 }
1950 }
1951 size_t max_live_bytes() { return _max_live_bytes; }
1952 size_t freed_bytes() { return _freed_bytes; }
1953 };
1954
1955 class G1ParScrubRemSetTask: public AbstractGangTask {
1956 protected:
1957 G1RemSet* _g1rs;
1958 BitMap* _region_bm;
1959 BitMap* _card_bm;
1960 HeapRegionClaimer _hrclaimer;
1961
1962 public:
1963 G1ParScrubRemSetTask(G1CollectedHeap* g1h, BitMap* region_bm, BitMap* card_bm, uint n_workers) :
1964 AbstractGangTask("G1 ScrubRS"), _g1rs(g1h->g1_rem_set()), _region_bm(region_bm), _card_bm(card_bm), _hrclaimer(n_workers) {
1965 }
1966
1967 void work(uint worker_id) {
1968 _g1rs->scrub(_region_bm, _card_bm, worker_id, &_hrclaimer);
1969 }
1970
1971 };
1972
1973 void ConcurrentMark::cleanup() {
1974 // world is stopped at this checkpoint
1975 assert(SafepointSynchronize::is_at_safepoint(),
1976 "world should be stopped");
1977 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1978
1979 // If a full collection has happened, we shouldn't do this.
1980 if (has_aborted()) {
1981 g1h->set_marking_complete(); // So bitmap clearing isn't confused
1982 return;
1983 }
1984
1985 g1h->verify_region_sets_optional();
1986
1987 if (VerifyDuringGC) {
1988 HandleMark hm; // handle scope
1989 Universe::heap()->prepare_for_verify();
1990 Universe::verify(VerifyOption_G1UsePrevMarking,
1991 " VerifyDuringGC:(before)");
1992 }
1993 g1h->check_bitmaps("Cleanup Start");
1994
1995 G1CollectorPolicy* g1p = G1CollectedHeap::heap()->g1_policy();
1996 g1p->record_concurrent_mark_cleanup_start();
1997
1998 double start = os::elapsedTime();
1999
2000 HeapRegionRemSet::reset_for_cleanup_tasks();
2001
2002 uint n_workers;
2003
2004 // Do counting once more with the world stopped for good measure.
2005 G1ParFinalCountTask g1_par_count_task(g1h, &_region_bm, &_card_bm);
2006
2007 g1h->set_par_threads();
2008 n_workers = g1h->n_par_threads();
2009 assert(g1h->n_par_threads() == n_workers,
2010 "Should not have been reset");
2011 g1h->workers()->run_task(&g1_par_count_task);
2012 // Done with the parallel phase so reset to 0.
2013 g1h->set_par_threads(0);
2014
2015 if (VerifyDuringGC) {
2016 // Verify that the counting data accumulated during marking matches
2017 // that calculated by walking the marking bitmap.
2018
2019 // Bitmaps to hold expected values
2020 BitMap expected_region_bm(_region_bm.size(), true);
2021 BitMap expected_card_bm(_card_bm.size(), true);
2022
2023 G1ParVerifyFinalCountTask g1_par_verify_task(g1h,
2024 &_region_bm,
2025 &_card_bm,
2026 &expected_region_bm,
2027 &expected_card_bm);
2028
2029 g1h->set_par_threads((int)n_workers);
2030 g1h->workers()->run_task(&g1_par_verify_task);
2031 // Done with the parallel phase so reset to 0.
2032 g1h->set_par_threads(0);
2033
2034 guarantee(g1_par_verify_task.failures() == 0, "Unexpected accounting failures");
2035 }
2036
2037 size_t start_used_bytes = g1h->used();
2038 g1h->set_marking_complete();
2039
2040 double count_end = os::elapsedTime();
2041 double this_final_counting_time = (count_end - start);
2042 _total_counting_time += this_final_counting_time;
2043
2044 if (G1PrintRegionLivenessInfo) {
2045 G1PrintRegionLivenessInfoClosure cl(gclog_or_tty, "Post-Marking");
2046 _g1h->heap_region_iterate(&cl);
2047 }
2048
2049 // Install newly created mark bitMap as "prev".
2050 swapMarkBitMaps();
2051
2052 g1h->reset_gc_time_stamp();
2053
2054 // Note end of marking in all heap regions.
2055 G1ParNoteEndTask g1_par_note_end_task(g1h, &_cleanup_list, n_workers);
2056 g1h->set_par_threads((int)n_workers);
2057 g1h->workers()->run_task(&g1_par_note_end_task);
2058 g1h->set_par_threads(0);
2059 g1h->check_gc_time_stamps();
2060
2061 if (!cleanup_list_is_empty()) {
2062 // The cleanup list is not empty, so we'll have to process it
2063 // concurrently. Notify anyone else that might be wanting free
2064 // regions that there will be more free regions coming soon.
2065 g1h->set_free_regions_coming();
2066 }
2067
2068 // call below, since it affects the metric by which we sort the heap
2069 // regions.
2070 if (G1ScrubRemSets) {
2071 double rs_scrub_start = os::elapsedTime();
2072 G1ParScrubRemSetTask g1_par_scrub_rs_task(g1h, &_region_bm, &_card_bm, n_workers);
2073 g1h->set_par_threads((int)n_workers);
2074 g1h->workers()->run_task(&g1_par_scrub_rs_task);
2075 g1h->set_par_threads(0);
2076
2077 double rs_scrub_end = os::elapsedTime();
2078 double this_rs_scrub_time = (rs_scrub_end - rs_scrub_start);
2079 _total_rs_scrub_time += this_rs_scrub_time;
2080 }
2081
2082 // this will also free any regions totally full of garbage objects,
2083 // and sort the regions.
2084 g1h->g1_policy()->record_concurrent_mark_cleanup_end((int)n_workers);
2085
2086 // Statistics.
2087 double end = os::elapsedTime();
2088 _cleanup_times.add((end - start) * 1000.0);
2089
2090 if (G1Log::fine()) {
2091 g1h->print_size_transition(gclog_or_tty,
2092 start_used_bytes,
2093 g1h->used(),
2094 g1h->capacity());
2095 }
2096
2097 // Clean up will have freed any regions completely full of garbage.
2098 // Update the soft reference policy with the new heap occupancy.
2099 Universe::update_heap_info_at_gc();
2100
2101 if (VerifyDuringGC) {
2102 HandleMark hm; // handle scope
2103 Universe::heap()->prepare_for_verify();
2104 Universe::verify(VerifyOption_G1UsePrevMarking,
2105 " VerifyDuringGC:(after)");
2106 }
2107
2108 g1h->check_bitmaps("Cleanup End");
2109
2110 g1h->verify_region_sets_optional();
2111
2112 // We need to make this be a "collection" so any collection pause that
2113 // races with it goes around and waits for completeCleanup to finish.
2114 g1h->increment_total_collections();
2115
2116 // Clean out dead classes and update Metaspace sizes.
2117 if (ClassUnloadingWithConcurrentMark) {
2118 ClassLoaderDataGraph::purge();
2119 }
2120 MetaspaceGC::compute_new_size();
2121
2122 // We reclaimed old regions so we should calculate the sizes to make
2123 // sure we update the old gen/space data.
2124 g1h->g1mm()->update_sizes();
2125 g1h->allocation_context_stats().update_after_mark();
2126
2127 g1h->trace_heap_after_concurrent_cycle();
2128 }
2129
2130 void ConcurrentMark::completeCleanup() {
2131 if (has_aborted()) return;
2132
2133 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2134
2135 _cleanup_list.verify_optional();
2136 FreeRegionList tmp_free_list("Tmp Free List");
2137
2138 if (G1ConcRegionFreeingVerbose) {
2139 gclog_or_tty->print_cr("G1ConcRegionFreeing [complete cleanup] : "
2140 "cleanup list has %u entries",
2141 _cleanup_list.length());
2142 }
2143
2144 // No one else should be accessing the _cleanup_list at this point,
2145 // so it is not necessary to take any locks
2146 while (!_cleanup_list.is_empty()) {
2147 HeapRegion* hr = _cleanup_list.remove_region(true /* from_head */);
2148 assert(hr != NULL, "Got NULL from a non-empty list");
2149 hr->par_clear();
2150 tmp_free_list.add_ordered(hr);
2151
2152 // Instead of adding one region at a time to the secondary_free_list,
2153 // we accumulate them in the local list and move them a few at a
2154 // time. This also cuts down on the number of notify_all() calls
2155 // we do during this process. We'll also append the local list when
2156 // _cleanup_list is empty (which means we just removed the last
2157 // region from the _cleanup_list).
2158 if ((tmp_free_list.length() % G1SecondaryFreeListAppendLength == 0) ||
2159 _cleanup_list.is_empty()) {
2160 if (G1ConcRegionFreeingVerbose) {
2161 gclog_or_tty->print_cr("G1ConcRegionFreeing [complete cleanup] : "
2162 "appending %u entries to the secondary_free_list, "
2163 "cleanup list still has %u entries",
2164 tmp_free_list.length(),
2165 _cleanup_list.length());
2166 }
2167
2168 {
2169 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
2170 g1h->secondary_free_list_add(&tmp_free_list);
2171 SecondaryFreeList_lock->notify_all();
2172 }
2173
2174 if (G1StressConcRegionFreeing) {
2175 for (uintx i = 0; i < G1StressConcRegionFreeingDelayMillis; ++i) {
2176 os::sleep(Thread::current(), (jlong) 1, false);
2177 }
2178 }
2179 }
2180 }
2181 assert(tmp_free_list.is_empty(), "post-condition");
2182 }
2183
2184 // Supporting Object and Oop closures for reference discovery
2185 // and processing in during marking
2186
2187 bool G1CMIsAliveClosure::do_object_b(oop obj) {
2188 HeapWord* addr = (HeapWord*)obj;
2189 return addr != NULL &&
2190 (!_g1->is_in_g1_reserved(addr) || !_g1->is_obj_ill(obj));
2191 }
2192
2193 // 'Keep Alive' oop closure used by both serial parallel reference processing.
2194 // Uses the CMTask associated with a worker thread (for serial reference
2195 // processing the CMTask for worker 0 is used) to preserve (mark) and
2196 // trace referent objects.
2197 //
2198 // Using the CMTask and embedded local queues avoids having the worker
2199 // threads operating on the global mark stack. This reduces the risk
2200 // of overflowing the stack - which we would rather avoid at this late
2201 // state. Also using the tasks' local queues removes the potential
2202 // of the workers interfering with each other that could occur if
2203 // operating on the global stack.
2204
2205 class G1CMKeepAliveAndDrainClosure: public OopClosure {
2206 ConcurrentMark* _cm;
2207 CMTask* _task;
2208 int _ref_counter_limit;
2209 int _ref_counter;
2210 bool _is_serial;
2211 public:
2212 G1CMKeepAliveAndDrainClosure(ConcurrentMark* cm, CMTask* task, bool is_serial) :
2213 _cm(cm), _task(task), _is_serial(is_serial),
2214 _ref_counter_limit(G1RefProcDrainInterval) {
2215 assert(_ref_counter_limit > 0, "sanity");
2216 assert(!_is_serial || _task->worker_id() == 0, "only task 0 for serial code");
2217 _ref_counter = _ref_counter_limit;
2218 }
2219
2220 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
2221 virtual void do_oop( oop* p) { do_oop_work(p); }
2222
2223 template <class T> void do_oop_work(T* p) {
2224 if (!_cm->has_overflown()) {
2225 oop obj = oopDesc::load_decode_heap_oop(p);
2226 if (_cm->verbose_high()) {
2227 gclog_or_tty->print_cr("\t[%u] we're looking at location "
2228 "*"PTR_FORMAT" = "PTR_FORMAT,
2229 _task->worker_id(), p2i(p), p2i((void*) obj));
2230 }
2231
2232 _task->deal_with_reference(obj);
2233 _ref_counter--;
2234
2235 if (_ref_counter == 0) {
2236 // We have dealt with _ref_counter_limit references, pushing them
2237 // and objects reachable from them on to the local stack (and
2238 // possibly the global stack). Call CMTask::do_marking_step() to
2239 // process these entries.
2240 //
2241 // We call CMTask::do_marking_step() in a loop, which we'll exit if
2242 // there's nothing more to do (i.e. we're done with the entries that
2243 // were pushed as a result of the CMTask::deal_with_reference() calls
2244 // above) or we overflow.
2245 //
2246 // Note: CMTask::do_marking_step() can set the CMTask::has_aborted()
2247 // flag while there may still be some work to do. (See the comment at
2248 // the beginning of CMTask::do_marking_step() for those conditions -
2249 // one of which is reaching the specified time target.) It is only
2250 // when CMTask::do_marking_step() returns without setting the
2251 // has_aborted() flag that the marking step has completed.
2252 do {
2253 double mark_step_duration_ms = G1ConcMarkStepDurationMillis;
2254 _task->do_marking_step(mark_step_duration_ms,
2255 false /* do_termination */,
2256 _is_serial);
2257 } while (_task->has_aborted() && !_cm->has_overflown());
2258 _ref_counter = _ref_counter_limit;
2259 }
2260 } else {
2261 if (_cm->verbose_high()) {
2262 gclog_or_tty->print_cr("\t[%u] CM Overflow", _task->worker_id());
2263 }
2264 }
2265 }
2266 };
2267
2268 // 'Drain' oop closure used by both serial and parallel reference processing.
2269 // Uses the CMTask associated with a given worker thread (for serial
2270 // reference processing the CMtask for worker 0 is used). Calls the
2271 // do_marking_step routine, with an unbelievably large timeout value,
2272 // to drain the marking data structures of the remaining entries
2273 // added by the 'keep alive' oop closure above.
2274
2275 class G1CMDrainMarkingStackClosure: public VoidClosure {
2276 ConcurrentMark* _cm;
2277 CMTask* _task;
2278 bool _is_serial;
2279 public:
2280 G1CMDrainMarkingStackClosure(ConcurrentMark* cm, CMTask* task, bool is_serial) :
2281 _cm(cm), _task(task), _is_serial(is_serial) {
2282 assert(!_is_serial || _task->worker_id() == 0, "only task 0 for serial code");
2283 }
2284
2285 void do_void() {
2286 do {
2287 if (_cm->verbose_high()) {
2288 gclog_or_tty->print_cr("\t[%u] Drain: Calling do_marking_step - serial: %s",
2289 _task->worker_id(), BOOL_TO_STR(_is_serial));
2290 }
2291
2292 // We call CMTask::do_marking_step() to completely drain the local
2293 // and global marking stacks of entries pushed by the 'keep alive'
2294 // oop closure (an instance of G1CMKeepAliveAndDrainClosure above).
2295 //
2296 // CMTask::do_marking_step() is called in a loop, which we'll exit
2297 // if there's nothing more to do (i.e. we've completely drained the
2298 // entries that were pushed as a a result of applying the 'keep alive'
2299 // closure to the entries on the discovered ref lists) or we overflow
2300 // the global marking stack.
2301 //
2302 // Note: CMTask::do_marking_step() can set the CMTask::has_aborted()
2303 // flag while there may still be some work to do. (See the comment at
2304 // the beginning of CMTask::do_marking_step() for those conditions -
2305 // one of which is reaching the specified time target.) It is only
2306 // when CMTask::do_marking_step() returns without setting the
2307 // has_aborted() flag that the marking step has completed.
2308
2309 _task->do_marking_step(1000000000.0 /* something very large */,
2310 true /* do_termination */,
2311 _is_serial);
2312 } while (_task->has_aborted() && !_cm->has_overflown());
2313 }
2314 };
2315
2316 // Implementation of AbstractRefProcTaskExecutor for parallel
2317 // reference processing at the end of G1 concurrent marking
2318
2319 class G1CMRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
2320 private:
2321 G1CollectedHeap* _g1h;
2322 ConcurrentMark* _cm;
2323 WorkGang* _workers;
2324 int _active_workers;
2325
2326 public:
2327 G1CMRefProcTaskExecutor(G1CollectedHeap* g1h,
2328 ConcurrentMark* cm,
2329 WorkGang* workers,
2330 int n_workers) :
2331 _g1h(g1h), _cm(cm),
2332 _workers(workers), _active_workers(n_workers) { }
2333
2334 // Executes the given task using concurrent marking worker threads.
2335 virtual void execute(ProcessTask& task);
2336 virtual void execute(EnqueueTask& task);
2337 };
2338
2339 class G1CMRefProcTaskProxy: public AbstractGangTask {
2340 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
2341 ProcessTask& _proc_task;
2342 G1CollectedHeap* _g1h;
2343 ConcurrentMark* _cm;
2344
2345 public:
2346 G1CMRefProcTaskProxy(ProcessTask& proc_task,
2347 G1CollectedHeap* g1h,
2348 ConcurrentMark* cm) :
2349 AbstractGangTask("Process reference objects in parallel"),
2350 _proc_task(proc_task), _g1h(g1h), _cm(cm) {
2351 ReferenceProcessor* rp = _g1h->ref_processor_cm();
2352 assert(rp->processing_is_mt(), "shouldn't be here otherwise");
2353 }
2354
2355 virtual void work(uint worker_id) {
2356 ResourceMark rm;
2357 HandleMark hm;
2358 CMTask* task = _cm->task(worker_id);
2359 G1CMIsAliveClosure g1_is_alive(_g1h);
2360 G1CMKeepAliveAndDrainClosure g1_par_keep_alive(_cm, task, false /* is_serial */);
2361 G1CMDrainMarkingStackClosure g1_par_drain(_cm, task, false /* is_serial */);
2362
2363 _proc_task.work(worker_id, g1_is_alive, g1_par_keep_alive, g1_par_drain);
2364 }
2365 };
2366
2367 void G1CMRefProcTaskExecutor::execute(ProcessTask& proc_task) {
2368 assert(_workers != NULL, "Need parallel worker threads.");
2369 assert(_g1h->ref_processor_cm()->processing_is_mt(), "processing is not MT");
2370
2371 G1CMRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _cm);
2372
2373 // We need to reset the concurrency level before each
2374 // proxy task execution, so that the termination protocol
2375 // and overflow handling in CMTask::do_marking_step() knows
2376 // how many workers to wait for.
2377 _cm->set_concurrency(_active_workers);
2378 _g1h->set_par_threads(_active_workers);
2379 _workers->run_task(&proc_task_proxy);
2380 _g1h->set_par_threads(0);
2381 }
2382
2383 class G1CMRefEnqueueTaskProxy: public AbstractGangTask {
2384 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
2385 EnqueueTask& _enq_task;
2386
2387 public:
2388 G1CMRefEnqueueTaskProxy(EnqueueTask& enq_task) :
2389 AbstractGangTask("Enqueue reference objects in parallel"),
2390 _enq_task(enq_task) { }
2391
2392 virtual void work(uint worker_id) {
2393 _enq_task.work(worker_id);
2394 }
2395 };
2396
2397 void G1CMRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
2398 assert(_workers != NULL, "Need parallel worker threads.");
2399 assert(_g1h->ref_processor_cm()->processing_is_mt(), "processing is not MT");
2400
2401 G1CMRefEnqueueTaskProxy enq_task_proxy(enq_task);
2402
2403 // Not strictly necessary but...
2404 //
2405 // We need to reset the concurrency level before each
2406 // proxy task execution, so that the termination protocol
2407 // and overflow handling in CMTask::do_marking_step() knows
2408 // how many workers to wait for.
2409 _cm->set_concurrency(_active_workers);
2410 _g1h->set_par_threads(_active_workers);
2411 _workers->run_task(&enq_task_proxy);
2412 _g1h->set_par_threads(0);
2413 }
2414
2415 void ConcurrentMark::weakRefsWorkParallelPart(BoolObjectClosure* is_alive, bool purged_classes) {
2416 G1CollectedHeap::heap()->parallel_cleaning(is_alive, true, true, purged_classes);
2417 }
2418
2419 void ConcurrentMark::weakRefsWork(bool clear_all_soft_refs) {
2420 if (has_overflown()) {
2421 // Skip processing the discovered references if we have
2422 // overflown the global marking stack. Reference objects
2423 // only get discovered once so it is OK to not
2424 // de-populate the discovered reference lists. We could have,
2425 // but the only benefit would be that, when marking restarts,
2426 // less reference objects are discovered.
2427 return;
2428 }
2429
2430 ResourceMark rm;
2431 HandleMark hm;
2432
2433 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2434
2435 // Is alive closure.
2436 G1CMIsAliveClosure g1_is_alive(g1h);
2437
2438 // Inner scope to exclude the cleaning of the string and symbol
2439 // tables from the displayed time.
2440 {
2441 G1CMTraceTime t("GC ref-proc", G1Log::finer());
2442
2443 ReferenceProcessor* rp = g1h->ref_processor_cm();
2444
2445 // See the comment in G1CollectedHeap::ref_processing_init()
2446 // about how reference processing currently works in G1.
2447
2448 // Set the soft reference policy
2449 rp->setup_policy(clear_all_soft_refs);
2450 assert(_markStack.isEmpty(), "mark stack should be empty");
2451
2452 // Instances of the 'Keep Alive' and 'Complete GC' closures used
2453 // in serial reference processing. Note these closures are also
2454 // used for serially processing (by the the current thread) the
2455 // JNI references during parallel reference processing.
2456 //
2457 // These closures do not need to synchronize with the worker
2458 // threads involved in parallel reference processing as these
2459 // instances are executed serially by the current thread (e.g.
2460 // reference processing is not multi-threaded and is thus
2461 // performed by the current thread instead of a gang worker).
2462 //
2463 // The gang tasks involved in parallel reference processing create
2464 // their own instances of these closures, which do their own
2465 // synchronization among themselves.
2466 G1CMKeepAliveAndDrainClosure g1_keep_alive(this, task(0), true /* is_serial */);
2467 G1CMDrainMarkingStackClosure g1_drain_mark_stack(this, task(0), true /* is_serial */);
2468
2469 // We need at least one active thread. If reference processing
2470 // is not multi-threaded we use the current (VMThread) thread,
2471 // otherwise we use the work gang from the G1CollectedHeap and
2472 // we utilize all the worker threads we can.
2473 bool processing_is_mt = rp->processing_is_mt();
2474 uint active_workers = (processing_is_mt ? g1h->workers()->active_workers() : 1U);
2475 active_workers = MAX2(MIN2(active_workers, _max_worker_id), 1U);
2476
2477 // Parallel processing task executor.
2478 G1CMRefProcTaskExecutor par_task_executor(g1h, this,
2479 g1h->workers(), active_workers);
2480 AbstractRefProcTaskExecutor* executor = (processing_is_mt ? &par_task_executor : NULL);
2481
2482 // Set the concurrency level. The phase was already set prior to
2483 // executing the remark task.
2484 set_concurrency(active_workers);
2485
2486 // Set the degree of MT processing here. If the discovery was done MT,
2487 // the number of threads involved during discovery could differ from
2488 // the number of active workers. This is OK as long as the discovered
2489 // Reference lists are balanced (see balance_all_queues() and balance_queues()).
2490 rp->set_active_mt_degree(active_workers);
2491
2492 // Process the weak references.
2493 const ReferenceProcessorStats& stats =
2494 rp->process_discovered_references(&g1_is_alive,
2495 &g1_keep_alive,
2496 &g1_drain_mark_stack,
2497 executor,
2498 g1h->gc_timer_cm(),
2499 concurrent_gc_id());
2500 g1h->gc_tracer_cm()->report_gc_reference_stats(stats);
2501
2502 // The do_oop work routines of the keep_alive and drain_marking_stack
2503 // oop closures will set the has_overflown flag if we overflow the
2504 // global marking stack.
2505
2506 assert(_markStack.overflow() || _markStack.isEmpty(),
2507 "mark stack should be empty (unless it overflowed)");
2508
2509 if (_markStack.overflow()) {
2510 // This should have been done already when we tried to push an
2511 // entry on to the global mark stack. But let's do it again.
2512 set_has_overflown();
2513 }
2514
2515 assert(rp->num_q() == active_workers, "why not");
2516
2517 rp->enqueue_discovered_references(executor);
2518
2519 rp->verify_no_references_recorded();
2520 assert(!rp->discovery_enabled(), "Post condition");
2521 }
2522
2523 if (has_overflown()) {
2524 // We can not trust g1_is_alive if the marking stack overflowed
2525 return;
2526 }
2527
2528 assert(_markStack.isEmpty(), "Marking should have completed");
2529
2530 // Unload Klasses, String, Symbols, Code Cache, etc.
2531 {
2532 G1CMTraceTime trace("Unloading", G1Log::finer());
2533
2534 if (ClassUnloadingWithConcurrentMark) {
2535 // Cleaning of klasses depends on correct information from MetadataMarkOnStack. The CodeCache::mark_on_stack
2536 // part is too slow to be done serially, so it is handled during the weakRefsWorkParallelPart phase.
2537 // Defer the cleaning until we have complete on_stack data.
2538 MetadataOnStackMark md_on_stack(false /* Don't visit the code cache at this point */);
2539
2540 bool purged_classes;
2541
2542 {
2543 G1CMTraceTime trace("System Dictionary Unloading", G1Log::finest());
2544 purged_classes = SystemDictionary::do_unloading(&g1_is_alive, false /* Defer klass cleaning */);
2545 }
2546
2547 {
2548 G1CMTraceTime trace("Parallel Unloading", G1Log::finest());
2549 weakRefsWorkParallelPart(&g1_is_alive, purged_classes);
2550 }
2551
2552 {
2553 G1CMTraceTime trace("Deallocate Metadata", G1Log::finest());
2554 ClassLoaderDataGraph::free_deallocate_lists();
2555 }
2556 }
2557
2558 if (G1StringDedup::is_enabled()) {
2559 G1CMTraceTime trace("String Deduplication Unlink", G1Log::finest());
2560 G1StringDedup::unlink(&g1_is_alive);
2561 }
2562 }
2563 }
2564
2565 void ConcurrentMark::swapMarkBitMaps() {
2566 CMBitMapRO* temp = _prevMarkBitMap;
2567 _prevMarkBitMap = (CMBitMapRO*)_nextMarkBitMap;
2568 _nextMarkBitMap = (CMBitMap*) temp;
2569 }
2570
2571 class CMObjectClosure;
2572
2573 // Closure for iterating over objects, currently only used for
2574 // processing SATB buffers.
2575 class CMObjectClosure : public ObjectClosure {
2576 private:
2577 CMTask* _task;
2578
2579 public:
2580 void do_object(oop obj) {
2581 _task->deal_with_reference(obj);
2582 }
2583
2584 CMObjectClosure(CMTask* task) : _task(task) { }
2585 };
2586
2587 class G1RemarkThreadsClosure : public ThreadClosure {
2588 CMObjectClosure _cm_obj;
2589 G1CMOopClosure _cm_cl;
2590 MarkingCodeBlobClosure _code_cl;
2591 int _thread_parity;
2592
2593 public:
2594 G1RemarkThreadsClosure(G1CollectedHeap* g1h, CMTask* task) :
2595 _cm_obj(task), _cm_cl(g1h, g1h->concurrent_mark(), task), _code_cl(&_cm_cl, !CodeBlobToOopClosure::FixRelocations),
2596 _thread_parity(SharedHeap::heap()->strong_roots_parity()) {}
2597
2598 void do_thread(Thread* thread) {
2599 if (thread->is_Java_thread()) {
2600 if (thread->claim_oops_do(true, _thread_parity)) {
2601 JavaThread* jt = (JavaThread*)thread;
2602
2603 // In theory it should not be neccessary to explicitly walk the nmethods to find roots for concurrent marking
2604 // however the liveness of oops reachable from nmethods have very complex lifecycles:
2605 // * Alive if on the stack of an executing method
2606 // * Weakly reachable otherwise
2607 // Some objects reachable from nmethods, such as the class loader (or klass_holder) of the receiver should be
2608 // live by the SATB invariant but other oops recorded in nmethods may behave differently.
2609 jt->nmethods_do(&_code_cl);
2610
2611 jt->satb_mark_queue().apply_closure_and_empty(&_cm_obj);
2612 }
2613 } else if (thread->is_VM_thread()) {
2614 if (thread->claim_oops_do(true, _thread_parity)) {
2615 JavaThread::satb_mark_queue_set().shared_satb_queue()->apply_closure_and_empty(&_cm_obj);
2616 }
2617 }
2618 }
2619 };
2620
2621 class CMRemarkTask: public AbstractGangTask {
2622 private:
2623 ConcurrentMark* _cm;
2624 public:
2625 void work(uint worker_id) {
2626 // Since all available tasks are actually started, we should
2627 // only proceed if we're supposed to be active.
2628 if (worker_id < _cm->active_tasks()) {
2629 CMTask* task = _cm->task(worker_id);
2630 task->record_start_time();
2631 {
2632 ResourceMark rm;
2633 HandleMark hm;
2634
2635 G1RemarkThreadsClosure threads_f(G1CollectedHeap::heap(), task);
2636 Threads::threads_do(&threads_f);
2637 }
2638
2639 do {
2640 task->do_marking_step(1000000000.0 /* something very large */,
2641 true /* do_termination */,
2642 false /* is_serial */);
2643 } while (task->has_aborted() && !_cm->has_overflown());
2644 // If we overflow, then we do not want to restart. We instead
2645 // want to abort remark and do concurrent marking again.
2646 task->record_end_time();
2647 }
2648 }
2649
2650 CMRemarkTask(ConcurrentMark* cm, int active_workers) :
2651 AbstractGangTask("Par Remark"), _cm(cm) {
2652 _cm->terminator()->reset_for_reuse(active_workers);
2653 }
2654 };
2655
2656 void ConcurrentMark::checkpointRootsFinalWork() {
2657 ResourceMark rm;
2658 HandleMark hm;
2659 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2660
2661 G1CMTraceTime trace("Finalize Marking", G1Log::finer());
2662
2663 g1h->ensure_parsability(false);
2664
2665 G1CollectedHeap::StrongRootsScope srs(g1h);
2666 // this is remark, so we'll use up all active threads
2667 uint active_workers = g1h->workers()->active_workers();
2668 if (active_workers == 0) {
2669 assert(active_workers > 0, "Should have been set earlier");
2670 active_workers = (uint) ParallelGCThreads;
2671 g1h->workers()->set_active_workers(active_workers);
2672 }
2673 set_concurrency_and_phase(active_workers, false /* concurrent */);
2674 // Leave _parallel_marking_threads at it's
2675 // value originally calculated in the ConcurrentMark
2676 // constructor and pass values of the active workers
2677 // through the gang in the task.
2678
2679 CMRemarkTask remarkTask(this, active_workers);
2680 // We will start all available threads, even if we decide that the
2681 // active_workers will be fewer. The extra ones will just bail out
2682 // immediately.
2683 g1h->set_par_threads(active_workers);
2684 g1h->workers()->run_task(&remarkTask);
2685 g1h->set_par_threads(0);
2686
2687 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
2688 guarantee(has_overflown() ||
2689 satb_mq_set.completed_buffers_num() == 0,
2690 err_msg("Invariant: has_overflown = %s, num buffers = %d",
2691 BOOL_TO_STR(has_overflown()),
2692 satb_mq_set.completed_buffers_num()));
2693
2694 print_stats();
2695 }
2696
2697 #ifndef PRODUCT
2698
2699 class PrintReachableOopClosure: public OopClosure {
2700 private:
2701 G1CollectedHeap* _g1h;
2702 outputStream* _out;
2703 VerifyOption _vo;
2704 bool _all;
2705
2706 public:
2707 PrintReachableOopClosure(outputStream* out,
2708 VerifyOption vo,
2709 bool all) :
2710 _g1h(G1CollectedHeap::heap()),
2711 _out(out), _vo(vo), _all(all) { }
2712
2713 void do_oop(narrowOop* p) { do_oop_work(p); }
2714 void do_oop( oop* p) { do_oop_work(p); }
2715
2716 template <class T> void do_oop_work(T* p) {
2717 oop obj = oopDesc::load_decode_heap_oop(p);
2718 const char* str = NULL;
2719 const char* str2 = "";
2720
2721 if (obj == NULL) {
2722 str = "";
2723 } else if (!_g1h->is_in_g1_reserved(obj)) {
2724 str = " O";
2725 } else {
2726 HeapRegion* hr = _g1h->heap_region_containing(obj);
2727 bool over_tams = _g1h->allocated_since_marking(obj, hr, _vo);
2728 bool marked = _g1h->is_marked(obj, _vo);
2729
2730 if (over_tams) {
2731 str = " >";
2732 if (marked) {
2733 str2 = " AND MARKED";
2734 }
2735 } else if (marked) {
2736 str = " M";
2737 } else {
2738 str = " NOT";
2739 }
2740 }
2741
2742 _out->print_cr(" "PTR_FORMAT": "PTR_FORMAT"%s%s",
2743 p2i(p), p2i((void*) obj), str, str2);
2744 }
2745 };
2746
2747 class PrintReachableObjectClosure : public ObjectClosure {
2748 private:
2749 G1CollectedHeap* _g1h;
2750 outputStream* _out;
2751 VerifyOption _vo;
2752 bool _all;
2753 HeapRegion* _hr;
2754
2755 public:
2756 PrintReachableObjectClosure(outputStream* out,
2757 VerifyOption vo,
2758 bool all,
2759 HeapRegion* hr) :
2760 _g1h(G1CollectedHeap::heap()),
2761 _out(out), _vo(vo), _all(all), _hr(hr) { }
2762
2763 void do_object(oop o) {
2764 bool over_tams = _g1h->allocated_since_marking(o, _hr, _vo);
2765 bool marked = _g1h->is_marked(o, _vo);
2766 bool print_it = _all || over_tams || marked;
2767
2768 if (print_it) {
2769 _out->print_cr(" "PTR_FORMAT"%s",
2770 p2i((void *)o), (over_tams) ? " >" : (marked) ? " M" : "");
2771 PrintReachableOopClosure oopCl(_out, _vo, _all);
2772 o->oop_iterate_no_header(&oopCl);
2773 }
2774 }
2775 };
2776
2777 class PrintReachableRegionClosure : public HeapRegionClosure {
2778 private:
2779 G1CollectedHeap* _g1h;
2780 outputStream* _out;
2781 VerifyOption _vo;
2782 bool _all;
2783
2784 public:
2785 bool doHeapRegion(HeapRegion* hr) {
2786 HeapWord* b = hr->bottom();
2787 HeapWord* e = hr->end();
2788 HeapWord* t = hr->top();
2789 HeapWord* p = _g1h->top_at_mark_start(hr, _vo);
2790 _out->print_cr("** ["PTR_FORMAT", "PTR_FORMAT"] top: "PTR_FORMAT" "
2791 "TAMS: " PTR_FORMAT, p2i(b), p2i(e), p2i(t), p2i(p));
2792 _out->cr();
2793
2794 HeapWord* from = b;
2795 HeapWord* to = t;
2796
2797 if (to > from) {
2798 _out->print_cr("Objects in [" PTR_FORMAT ", " PTR_FORMAT "]", p2i(from), p2i(to));
2799 _out->cr();
2800 PrintReachableObjectClosure ocl(_out, _vo, _all, hr);
2801 hr->object_iterate_mem_careful(MemRegion(from, to), &ocl);
2802 _out->cr();
2803 }
2804
2805 return false;
2806 }
2807
2808 PrintReachableRegionClosure(outputStream* out,
2809 VerifyOption vo,
2810 bool all) :
2811 _g1h(G1CollectedHeap::heap()), _out(out), _vo(vo), _all(all) { }
2812 };
2813
2814 void ConcurrentMark::print_reachable(const char* str,
2815 VerifyOption vo,
2816 bool all) {
2817 gclog_or_tty->cr();
2818 gclog_or_tty->print_cr("== Doing heap dump... ");
2819
2820 if (G1PrintReachableBaseFile == NULL) {
2821 gclog_or_tty->print_cr(" #### error: no base file defined");
2822 return;
2823 }
2824
2825 if (strlen(G1PrintReachableBaseFile) + 1 + strlen(str) >
2826 (JVM_MAXPATHLEN - 1)) {
2827 gclog_or_tty->print_cr(" #### error: file name too long");
2828 return;
2829 }
2830
2831 char file_name[JVM_MAXPATHLEN];
2832 sprintf(file_name, "%s.%s", G1PrintReachableBaseFile, str);
2833 gclog_or_tty->print_cr(" dumping to file %s", file_name);
2834
2835 fileStream fout(file_name);
2836 if (!fout.is_open()) {
2837 gclog_or_tty->print_cr(" #### error: could not open file");
2838 return;
2839 }
2840
2841 outputStream* out = &fout;
2842 out->print_cr("-- USING %s", _g1h->top_at_mark_start_str(vo));
2843 out->cr();
2844
2845 out->print_cr("--- ITERATING OVER REGIONS");
2846 out->cr();
2847 PrintReachableRegionClosure rcl(out, vo, all);
2848 _g1h->heap_region_iterate(&rcl);
2849 out->cr();
2850
2851 gclog_or_tty->print_cr(" done");
2852 gclog_or_tty->flush();
2853 }
2854
2855 #endif // PRODUCT
2856
2857 void ConcurrentMark::clearRangePrevBitmap(MemRegion mr) {
2858 // Note we are overriding the read-only view of the prev map here, via
2859 // the cast.
2860 ((CMBitMap*)_prevMarkBitMap)->clearRange(mr);
2861 }
2862
2863 void ConcurrentMark::clearRangeNextBitmap(MemRegion mr) {
2864 _nextMarkBitMap->clearRange(mr);
2865 }
2866
2867 HeapRegion*
2868 ConcurrentMark::claim_region(uint worker_id) {
2869 // "checkpoint" the finger
2870 HeapWord* finger = _finger;
2871
2872 // _heap_end will not change underneath our feet; it only changes at
2873 // yield points.
2874 while (finger < _heap_end) {
2875 assert(_g1h->is_in_g1_reserved(finger), "invariant");
2876
2877 // Note on how this code handles humongous regions. In the
2878 // normal case the finger will reach the start of a "starts
2879 // humongous" (SH) region. Its end will either be the end of the
2880 // last "continues humongous" (CH) region in the sequence, or the
2881 // standard end of the SH region (if the SH is the only region in
2882 // the sequence). That way claim_region() will skip over the CH
2883 // regions. However, there is a subtle race between a CM thread
2884 // executing this method and a mutator thread doing a humongous
2885 // object allocation. The two are not mutually exclusive as the CM
2886 // thread does not need to hold the Heap_lock when it gets
2887 // here. So there is a chance that claim_region() will come across
2888 // a free region that's in the progress of becoming a SH or a CH
2889 // region. In the former case, it will either
2890 // a) Miss the update to the region's end, in which case it will
2891 // visit every subsequent CH region, will find their bitmaps
2892 // empty, and do nothing, or
2893 // b) Will observe the update of the region's end (in which case
2894 // it will skip the subsequent CH regions).
2895 // If it comes across a region that suddenly becomes CH, the
2896 // scenario will be similar to b). So, the race between
2897 // claim_region() and a humongous object allocation might force us
2898 // to do a bit of unnecessary work (due to some unnecessary bitmap
2899 // iterations) but it should not introduce and correctness issues.
2900 HeapRegion* curr_region = _g1h->heap_region_containing_raw(finger);
2901
2902 // Above heap_region_containing_raw may return NULL as we always scan claim
2903 // until the end of the heap. In this case, just jump to the next region.
2904 HeapWord* end = curr_region != NULL ? curr_region->end() : finger + HeapRegion::GrainWords;
2905
2906 // Is the gap between reading the finger and doing the CAS too long?
2907 HeapWord* res = (HeapWord*) Atomic::cmpxchg_ptr(end, &_finger, finger);
2908 if (res == finger && curr_region != NULL) {
2909 // we succeeded
2910 HeapWord* bottom = curr_region->bottom();
2911 HeapWord* limit = curr_region->next_top_at_mark_start();
2912
2913 if (verbose_low()) {
2914 gclog_or_tty->print_cr("[%u] curr_region = "PTR_FORMAT" "
2915 "["PTR_FORMAT", "PTR_FORMAT"), "
2916 "limit = "PTR_FORMAT,
2917 worker_id, p2i(curr_region), p2i(bottom), p2i(end), p2i(limit));
2918 }
2919
2920 // notice that _finger == end cannot be guaranteed here since,
2921 // someone else might have moved the finger even further
2922 assert(_finger >= end, "the finger should have moved forward");
2923
2924 if (verbose_low()) {
2925 gclog_or_tty->print_cr("[%u] we were successful with region = "
2926 PTR_FORMAT, worker_id, p2i(curr_region));
2927 }
2928
2929 if (limit > bottom) {
2930 if (verbose_low()) {
2931 gclog_or_tty->print_cr("[%u] region "PTR_FORMAT" is not empty, "
2932 "returning it ", worker_id, p2i(curr_region));
2933 }
2934 return curr_region;
2935 } else {
2936 assert(limit == bottom,
2937 "the region limit should be at bottom");
2938 if (verbose_low()) {
2939 gclog_or_tty->print_cr("[%u] region "PTR_FORMAT" is empty, "
2940 "returning NULL", worker_id, p2i(curr_region));
2941 }
2942 // we return NULL and the caller should try calling
2943 // claim_region() again.
2944 return NULL;
2945 }
2946 } else {
2947 assert(_finger > finger, "the finger should have moved forward");
2948 if (verbose_low()) {
2949 if (curr_region == NULL) {
2950 gclog_or_tty->print_cr("[%u] found uncommitted region, moving finger, "
2951 "global finger = "PTR_FORMAT", "
2952 "our finger = "PTR_FORMAT,
2953 worker_id, p2i(_finger), p2i(finger));
2954 } else {
2955 gclog_or_tty->print_cr("[%u] somebody else moved the finger, "
2956 "global finger = "PTR_FORMAT", "
2957 "our finger = "PTR_FORMAT,
2958 worker_id, p2i(_finger), p2i(finger));
2959 }
2960 }
2961
2962 // read it again
2963 finger = _finger;
2964 }
2965 }
2966
2967 return NULL;
2968 }
2969
2970 #ifndef PRODUCT
2971 enum VerifyNoCSetOopsPhase {
2972 VerifyNoCSetOopsStack,
2973 VerifyNoCSetOopsQueues,
2974 VerifyNoCSetOopsSATBCompleted,
2975 VerifyNoCSetOopsSATBThread
2976 };
2977
2978 class VerifyNoCSetOopsClosure : public OopClosure, public ObjectClosure {
2979 private:
2980 G1CollectedHeap* _g1h;
2981 ConcurrentMark* _cm;
2982 VerifyNoCSetOopsPhase _phase;
2983 int _info;
2984
2985 const char* phase_str() {
2986 switch (_phase) {
2987 case VerifyNoCSetOopsStack: return "Stack";
2988 case VerifyNoCSetOopsQueues: return "Queue";
2989 case VerifyNoCSetOopsSATBCompleted: return "Completed SATB Buffers";
2990 case VerifyNoCSetOopsSATBThread: return "Thread SATB Buffers";
2991 default: ShouldNotReachHere();
2992 }
2993 return NULL;
2994 }
2995
2996 void do_object_work(oop obj) {
2997 switch (_phase) {
2998 case VerifyNoCSetOopsStack:
2999 case VerifyNoCSetOopsQueues:
3000 // Ignore reclaimed humongous object entries in mark stack and
3001 // thread queues.
3002 if (_cm->is_stale_humongous_marked_entry(obj)) break;
3003 default:
3004 guarantee(!_g1h->obj_in_cs(obj),
3005 err_msg("obj: "PTR_FORMAT" in CSet, phase: %s, info: %d",
3006 p2i((void*) obj), phase_str(), _info));
3007 }
3008 }
3009
3010 public:
3011 VerifyNoCSetOopsClosure(G1CollectedHeap* g1h, ConcurrentMark* cm)
3012 : _g1h(g1h), _cm(cm) { }
3013
3014 void set_phase(VerifyNoCSetOopsPhase phase, int info = -1) {
3015 _phase = phase;
3016 _info = info;
3017 }
3018
3019 virtual void do_oop(oop* p) {
3020 oop obj = oopDesc::load_decode_heap_oop(p);
3021 do_object_work(obj);
3022 }
3023
3024 virtual void do_oop(narrowOop* p) {
3025 // We should not come across narrow oops while scanning marking
3026 // stacks and SATB buffers.
3027 ShouldNotReachHere();
3028 }
3029
3030 virtual void do_object(oop obj) {
3031 do_object_work(obj);
3032 }
3033 };
3034
3035 void ConcurrentMark::verify_no_cset_oops(bool verify_stacks,
3036 bool verify_enqueued_buffers,
3037 bool verify_thread_buffers,
3038 bool verify_fingers) {
3039 assert(SafepointSynchronize::is_at_safepoint(), "should be at a safepoint");
3040 if (!G1CollectedHeap::heap()->mark_in_progress()) {
3041 return;
3042 }
3043
3044 VerifyNoCSetOopsClosure cl(_g1h, this);
3045
3046 if (verify_stacks) {
3047 // Verify entries on the global mark stack
3048 cl.set_phase(VerifyNoCSetOopsStack);
3049 _markStack.oops_do(&cl);
3050
3051 // Verify entries on the task queues
3052 for (uint i = 0; i < _max_worker_id; i += 1) {
3053 cl.set_phase(VerifyNoCSetOopsQueues, i);
3054 CMTaskQueue* queue = _task_queues->queue(i);
3055 queue->oops_do(&cl);
3056 }
3057 }
3058
3059 SATBMarkQueueSet& satb_qs = JavaThread::satb_mark_queue_set();
3060
3061 // Verify entries on the enqueued SATB buffers
3062 if (verify_enqueued_buffers) {
3063 cl.set_phase(VerifyNoCSetOopsSATBCompleted);
3064 satb_qs.iterate_completed_buffers_read_only(&cl);
3065 }
3066
3067 // Verify entries on the per-thread SATB buffers
3068 if (verify_thread_buffers) {
3069 cl.set_phase(VerifyNoCSetOopsSATBThread);
3070 satb_qs.iterate_thread_buffers_read_only(&cl);
3071 }
3072
3073 if (verify_fingers) {
3074 // Verify the global finger
3075 HeapWord* global_finger = finger();
3076 if (global_finger != NULL && global_finger < _heap_end) {
3077 // The global finger always points to a heap region boundary. We
3078 // use heap_region_containing_raw() to get the containing region
3079 // given that the global finger could be pointing to a free region
3080 // which subsequently becomes continues humongous. If that
3081 // happens, heap_region_containing() will return the bottom of the
3082 // corresponding starts humongous region and the check below will
3083 // not hold any more.
3084 // Since we always iterate over all regions, we might get a NULL HeapRegion
3085 // here.
3086 HeapRegion* global_hr = _g1h->heap_region_containing_raw(global_finger);
3087 guarantee(global_hr == NULL || global_finger == global_hr->bottom(),
3088 err_msg("global finger: "PTR_FORMAT" region: "HR_FORMAT,
3089 p2i(global_finger), HR_FORMAT_PARAMS(global_hr)));
3090 }
3091
3092 // Verify the task fingers
3093 assert(parallel_marking_threads() <= _max_worker_id, "sanity");
3094 for (int i = 0; i < (int) parallel_marking_threads(); i += 1) {
3095 CMTask* task = _tasks[i];
3096 HeapWord* task_finger = task->finger();
3097 if (task_finger != NULL && task_finger < _heap_end) {
3098 // See above note on the global finger verification.
3099 HeapRegion* task_hr = _g1h->heap_region_containing_raw(task_finger);
3100 guarantee(task_hr == NULL || task_finger == task_hr->bottom() ||
3101 !task_hr->in_collection_set(),
3102 err_msg("task finger: "PTR_FORMAT" region: "HR_FORMAT,
3103 p2i(task_finger), HR_FORMAT_PARAMS(task_hr)));
3104 }
3105 }
3106 }
3107 }
3108 #endif // PRODUCT
3109
3110 // Aggregate the counting data that was constructed concurrently
3111 // with marking.
3112 class AggregateCountDataHRClosure: public HeapRegionClosure {
3113 G1CollectedHeap* _g1h;
3114 ConcurrentMark* _cm;
3115 CardTableModRefBS* _ct_bs;
3116 BitMap* _cm_card_bm;
3117 uint _max_worker_id;
3118
3119 public:
3120 AggregateCountDataHRClosure(G1CollectedHeap* g1h,
3121 BitMap* cm_card_bm,
3122 uint max_worker_id) :
3123 _g1h(g1h), _cm(g1h->concurrent_mark()),
3124 _ct_bs(barrier_set_cast<CardTableModRefBS>(g1h->barrier_set())),
3125 _cm_card_bm(cm_card_bm), _max_worker_id(max_worker_id) { }
3126
3127 bool doHeapRegion(HeapRegion* hr) {
3128 if (hr->is_continues_humongous()) {
3129 // We will ignore these here and process them when their
3130 // associated "starts humongous" region is processed.
3131 // Note that we cannot rely on their associated
3132 // "starts humongous" region to have their bit set to 1
3133 // since, due to the region chunking in the parallel region
3134 // iteration, a "continues humongous" region might be visited
3135 // before its associated "starts humongous".
3136 return false;
3137 }
3138
3139 HeapWord* start = hr->bottom();
3140 HeapWord* limit = hr->next_top_at_mark_start();
3141 HeapWord* end = hr->end();
3142
3143 assert(start <= limit && limit <= hr->top() && hr->top() <= hr->end(),
3144 err_msg("Preconditions not met - "
3145 "start: "PTR_FORMAT", limit: "PTR_FORMAT", "
3146 "top: "PTR_FORMAT", end: "PTR_FORMAT,
3147 p2i(start), p2i(limit), p2i(hr->top()), p2i(hr->end())));
3148
3149 assert(hr->next_marked_bytes() == 0, "Precondition");
3150
3151 if (start == limit) {
3152 // NTAMS of this region has not been set so nothing to do.
3153 return false;
3154 }
3155
3156 // 'start' should be in the heap.
3157 assert(_g1h->is_in_g1_reserved(start) && _ct_bs->is_card_aligned(start), "sanity");
3158 // 'end' *may* be just beyond the end of the heap (if hr is the last region)
3159 assert(!_g1h->is_in_g1_reserved(end) || _ct_bs->is_card_aligned(end), "sanity");
3160
3161 BitMap::idx_t start_idx = _cm->card_bitmap_index_for(start);
3162 BitMap::idx_t limit_idx = _cm->card_bitmap_index_for(limit);
3163 BitMap::idx_t end_idx = _cm->card_bitmap_index_for(end);
3164
3165 // If ntams is not card aligned then we bump card bitmap index
3166 // for limit so that we get the all the cards spanned by
3167 // the object ending at ntams.
3168 // Note: if this is the last region in the heap then ntams
3169 // could be actually just beyond the end of the the heap;
3170 // limit_idx will then correspond to a (non-existent) card
3171 // that is also outside the heap.
3172 if (_g1h->is_in_g1_reserved(limit) && !_ct_bs->is_card_aligned(limit)) {
3173 limit_idx += 1;
3174 }
3175
3176 assert(limit_idx <= end_idx, "or else use atomics");
3177
3178 // Aggregate the "stripe" in the count data associated with hr.
3179 uint hrm_index = hr->hrm_index();
3180 size_t marked_bytes = 0;
3181
3182 for (uint i = 0; i < _max_worker_id; i += 1) {
3183 size_t* marked_bytes_array = _cm->count_marked_bytes_array_for(i);
3184 BitMap* task_card_bm = _cm->count_card_bitmap_for(i);
3185
3186 // Fetch the marked_bytes in this region for task i and
3187 // add it to the running total for this region.
3188 marked_bytes += marked_bytes_array[hrm_index];
3189
3190 // Now union the bitmaps[0,max_worker_id)[start_idx..limit_idx)
3191 // into the global card bitmap.
3192 BitMap::idx_t scan_idx = task_card_bm->get_next_one_offset(start_idx, limit_idx);
3193
3194 while (scan_idx < limit_idx) {
3195 assert(task_card_bm->at(scan_idx) == true, "should be");
3196 _cm_card_bm->set_bit(scan_idx);
3197 assert(_cm_card_bm->at(scan_idx) == true, "should be");
3198
3199 // BitMap::get_next_one_offset() can handle the case when
3200 // its left_offset parameter is greater than its right_offset
3201 // parameter. It does, however, have an early exit if
3202 // left_offset == right_offset. So let's limit the value
3203 // passed in for left offset here.
3204 BitMap::idx_t next_idx = MIN2(scan_idx + 1, limit_idx);
3205 scan_idx = task_card_bm->get_next_one_offset(next_idx, limit_idx);
3206 }
3207 }
3208
3209 // Update the marked bytes for this region.
3210 hr->add_to_marked_bytes(marked_bytes);
3211
3212 // Next heap region
3213 return false;
3214 }
3215 };
3216
3217 class G1AggregateCountDataTask: public AbstractGangTask {
3218 protected:
3219 G1CollectedHeap* _g1h;
3220 ConcurrentMark* _cm;
3221 BitMap* _cm_card_bm;
3222 uint _max_worker_id;
3223 int _active_workers;
3224 HeapRegionClaimer _hrclaimer;
3225
3226 public:
3227 G1AggregateCountDataTask(G1CollectedHeap* g1h,
3228 ConcurrentMark* cm,
3229 BitMap* cm_card_bm,
3230 uint max_worker_id,
3231 int n_workers) :
3232 AbstractGangTask("Count Aggregation"),
3233 _g1h(g1h), _cm(cm), _cm_card_bm(cm_card_bm),
3234 _max_worker_id(max_worker_id),
3235 _active_workers(n_workers),
3236 _hrclaimer(_active_workers) {
3237 }
3238
3239 void work(uint worker_id) {
3240 AggregateCountDataHRClosure cl(_g1h, _cm_card_bm, _max_worker_id);
3241
3242 _g1h->heap_region_par_iterate(&cl, worker_id, &_hrclaimer);
3243 }
3244 };
3245
3246
3247 void ConcurrentMark::aggregate_count_data() {
3248 int n_workers = _g1h->workers()->active_workers();
3249
3250 G1AggregateCountDataTask g1_par_agg_task(_g1h, this, &_card_bm,
3251 _max_worker_id, n_workers);
3252
3253 _g1h->set_par_threads(n_workers);
3254 _g1h->workers()->run_task(&g1_par_agg_task);
3255 _g1h->set_par_threads(0);
3256 }
3257
3258 // Clear the per-worker arrays used to store the per-region counting data
3259 void ConcurrentMark::clear_all_count_data() {
3260 // Clear the global card bitmap - it will be filled during
3261 // liveness count aggregation (during remark) and the
3262 // final counting task.
3263 _card_bm.clear();
3264
3265 // Clear the global region bitmap - it will be filled as part
3266 // of the final counting task.
3267 _region_bm.clear();
3268
3269 uint max_regions = _g1h->max_regions();
3270 assert(_max_worker_id > 0, "uninitialized");
3271
3272 for (uint i = 0; i < _max_worker_id; i += 1) {
3273 BitMap* task_card_bm = count_card_bitmap_for(i);
3274 size_t* marked_bytes_array = count_marked_bytes_array_for(i);
3275
3276 assert(task_card_bm->size() == _card_bm.size(), "size mismatch");
3277 assert(marked_bytes_array != NULL, "uninitialized");
3278
3279 memset(marked_bytes_array, 0, (size_t) max_regions * sizeof(size_t));
3280 task_card_bm->clear();
3281 }
3282 }
3283
3284 void ConcurrentMark::print_stats() {
3285 if (verbose_stats()) {
3286 gclog_or_tty->print_cr("---------------------------------------------------------------------");
3287 for (size_t i = 0; i < _active_tasks; ++i) {
3288 _tasks[i]->print_stats();
3289 gclog_or_tty->print_cr("---------------------------------------------------------------------");
3290 }
3291 }
3292 }
3293
3294 // abandon current marking iteration due to a Full GC
3295 void ConcurrentMark::abort() {
3296 // Clear all marks in the next bitmap for the next marking cycle. This will allow us to skip the next
3297 // concurrent bitmap clearing.
3298 _nextMarkBitMap->clearAll();
3299
3300 // Note we cannot clear the previous marking bitmap here
3301 // since VerifyDuringGC verifies the objects marked during
3302 // a full GC against the previous bitmap.
3303
3304 // Clear the liveness counting data
3305 clear_all_count_data();
3306 // Empty mark stack
3307 reset_marking_state();
3308 for (uint i = 0; i < _max_worker_id; ++i) {
3309 _tasks[i]->clear_region_fields();
3310 }
3311 _first_overflow_barrier_sync.abort();
3312 _second_overflow_barrier_sync.abort();
3313 const GCId& gc_id = _g1h->gc_tracer_cm()->gc_id();
3314 if (!gc_id.is_undefined()) {
3315 // We can do multiple full GCs before ConcurrentMarkThread::run() gets a chance
3316 // to detect that it was aborted. Only keep track of the first GC id that we aborted.
3317 _aborted_gc_id = gc_id;
3318 }
3319 _has_aborted = true;
3320
3321 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
3322 satb_mq_set.abandon_partial_marking();
3323 // This can be called either during or outside marking, we'll read
3324 // the expected_active value from the SATB queue set.
3325 satb_mq_set.set_active_all_threads(
3326 false, /* new active value */
3327 satb_mq_set.is_active() /* expected_active */);
3328
3329 _g1h->trace_heap_after_concurrent_cycle();
3330 _g1h->register_concurrent_cycle_end();
3331 }
3332
3333 const GCId& ConcurrentMark::concurrent_gc_id() {
3334 if (has_aborted()) {
3335 return _aborted_gc_id;
3336 }
3337 return _g1h->gc_tracer_cm()->gc_id();
3338 }
3339
3340 static void print_ms_time_info(const char* prefix, const char* name,
3341 NumberSeq& ns) {
3342 gclog_or_tty->print_cr("%s%5d %12s: total time = %8.2f s (avg = %8.2f ms).",
3343 prefix, ns.num(), name, ns.sum()/1000.0, ns.avg());
3344 if (ns.num() > 0) {
3345 gclog_or_tty->print_cr("%s [std. dev = %8.2f ms, max = %8.2f ms]",
3346 prefix, ns.sd(), ns.maximum());
3347 }
3348 }
3349
3350 void ConcurrentMark::print_summary_info() {
3351 gclog_or_tty->print_cr(" Concurrent marking:");
3352 print_ms_time_info(" ", "init marks", _init_times);
3353 print_ms_time_info(" ", "remarks", _remark_times);
3354 {
3355 print_ms_time_info(" ", "final marks", _remark_mark_times);
3356 print_ms_time_info(" ", "weak refs", _remark_weak_ref_times);
3357
3358 }
3359 print_ms_time_info(" ", "cleanups", _cleanup_times);
3360 gclog_or_tty->print_cr(" Final counting total time = %8.2f s (avg = %8.2f ms).",
3361 _total_counting_time,
3362 (_cleanup_times.num() > 0 ? _total_counting_time * 1000.0 /
3363 (double)_cleanup_times.num()
3364 : 0.0));
3365 if (G1ScrubRemSets) {
3366 gclog_or_tty->print_cr(" RS scrub total time = %8.2f s (avg = %8.2f ms).",
3367 _total_rs_scrub_time,
3368 (_cleanup_times.num() > 0 ? _total_rs_scrub_time * 1000.0 /
3369 (double)_cleanup_times.num()
3370 : 0.0));
3371 }
3372 gclog_or_tty->print_cr(" Total stop_world time = %8.2f s.",
3373 (_init_times.sum() + _remark_times.sum() +
3374 _cleanup_times.sum())/1000.0);
3375 gclog_or_tty->print_cr(" Total concurrent time = %8.2f s "
3376 "(%8.2f s marking).",
3377 cmThread()->vtime_accum(),
3378 cmThread()->vtime_mark_accum());
3379 }
3380
3381 void ConcurrentMark::print_worker_threads_on(outputStream* st) const {
3382 _parallel_workers->print_worker_threads_on(st);
3383 }
3384
3385 void ConcurrentMark::print_on_error(outputStream* st) const {
3386 st->print_cr("Marking Bits (Prev, Next): (CMBitMap*) " PTR_FORMAT ", (CMBitMap*) " PTR_FORMAT,
3387 p2i(_prevMarkBitMap), p2i(_nextMarkBitMap));
3388 _prevMarkBitMap->print_on_error(st, " Prev Bits: ");
3389 _nextMarkBitMap->print_on_error(st, " Next Bits: ");
3390 }
3391
3392 // We take a break if someone is trying to stop the world.
3393 bool ConcurrentMark::do_yield_check(uint worker_id) {
3394 if (SuspendibleThreadSet::should_yield()) {
3395 if (worker_id == 0) {
3396 _g1h->g1_policy()->record_concurrent_pause();
3397 }
3398 SuspendibleThreadSet::yield();
3399 return true;
3400 } else {
3401 return false;
3402 }
3403 }
3404
3405 #ifndef PRODUCT
3406 // for debugging purposes
3407 void ConcurrentMark::print_finger() {
3408 gclog_or_tty->print_cr("heap ["PTR_FORMAT", "PTR_FORMAT"), global finger = "PTR_FORMAT,
3409 p2i(_heap_start), p2i(_heap_end), p2i(_finger));
3410 for (uint i = 0; i < _max_worker_id; ++i) {
3411 gclog_or_tty->print(" %u: " PTR_FORMAT, i, p2i(_tasks[i]->finger()));
3412 }
3413 gclog_or_tty->cr();
3414 }
3415 #endif
3416
3417 void CMTask::scan_object(oop obj) {
3418 assert(_nextMarkBitMap->isMarked((HeapWord*) obj), "invariant");
3419 assert(!_g1h->is_on_master_free_list(_g1h->heap_region_containing(obj)), "invariant");
3420
3421 if (_cm->verbose_high()) {
3422 gclog_or_tty->print_cr("[%u] we're scanning object "PTR_FORMAT,
3423 _worker_id, p2i((void*) obj));
3424 }
3425
3426 size_t obj_size = obj->size();
3427 _words_scanned += obj_size;
3428
3429 obj->oop_iterate(_cm_oop_closure);
3430 statsOnly( ++_objs_scanned );
3431 check_limits();
3432 }
3433
3434 // Closure for iteration over bitmaps
3435 class CMBitMapClosure : public BitMapClosure {
3436 private:
3437 // the bitmap that is being iterated over
3438 CMBitMap* _nextMarkBitMap;
3439 ConcurrentMark* _cm;
3440 CMTask* _task;
3441
3442 public:
3443 CMBitMapClosure(CMTask *task, ConcurrentMark* cm, CMBitMap* nextMarkBitMap) :
3444 _task(task), _cm(cm), _nextMarkBitMap(nextMarkBitMap) { }
3445
3446 bool do_bit(size_t offset) {
3447 HeapWord* addr = _nextMarkBitMap->offsetToHeapWord(offset);
3448 assert(_nextMarkBitMap->isMarked(addr), "invariant");
3449 assert( addr < _cm->finger(), "invariant");
3450
3451 statsOnly( _task->increase_objs_found_on_bitmap() );
3452 assert(addr >= _task->finger(), "invariant");
3453
3454 // We move that task's local finger along.
3455 _task->move_finger_to(addr);
3456
3457 _task->scan_object(oop(addr));
3458 // we only partially drain the local queue and global stack
3459 _task->drain_local_queue(true);
3460 _task->drain_global_stack(true);
3461
3462 // if the has_aborted flag has been raised, we need to bail out of
3463 // the iteration
3464 return !_task->has_aborted();
3465 }
3466 };
3467
3468 G1CMOopClosure::G1CMOopClosure(G1CollectedHeap* g1h,
3469 ConcurrentMark* cm,
3470 CMTask* task)
3471 : _g1h(g1h), _cm(cm), _task(task) {
3472 assert(_ref_processor == NULL, "should be initialized to NULL");
3473
3474 if (G1UseConcMarkReferenceProcessing) {
3475 _ref_processor = g1h->ref_processor_cm();
3476 assert(_ref_processor != NULL, "should not be NULL");
3477 }
3478 }
3479
3480 void CMTask::setup_for_region(HeapRegion* hr) {
3481 assert(hr != NULL,
3482 "claim_region() should have filtered out NULL regions");
3483 assert(!hr->is_continues_humongous(),
3484 "claim_region() should have filtered out continues humongous regions");
3485
3486 if (_cm->verbose_low()) {
3487 gclog_or_tty->print_cr("[%u] setting up for region "PTR_FORMAT,
3488 _worker_id, p2i(hr));
3489 }
3490
3491 _curr_region = hr;
3492 _finger = hr->bottom();
3493 update_region_limit();
3494 }
3495
3496 void CMTask::update_region_limit() {
3497 HeapRegion* hr = _curr_region;
3498 HeapWord* bottom = hr->bottom();
3499 HeapWord* limit = hr->next_top_at_mark_start();
3500
3501 if (limit == bottom) {
3502 if (_cm->verbose_low()) {
3503 gclog_or_tty->print_cr("[%u] found an empty region "
3504 "["PTR_FORMAT", "PTR_FORMAT")",
3505 _worker_id, p2i(bottom), p2i(limit));
3506 }
3507 // The region was collected underneath our feet.
3508 // We set the finger to bottom to ensure that the bitmap
3509 // iteration that will follow this will not do anything.
3510 // (this is not a condition that holds when we set the region up,
3511 // as the region is not supposed to be empty in the first place)
3512 _finger = bottom;
3513 } else if (limit >= _region_limit) {
3514 assert(limit >= _finger, "peace of mind");
3515 } else {
3516 assert(limit < _region_limit, "only way to get here");
3517 // This can happen under some pretty unusual circumstances. An
3518 // evacuation pause empties the region underneath our feet (NTAMS
3519 // at bottom). We then do some allocation in the region (NTAMS
3520 // stays at bottom), followed by the region being used as a GC
3521 // alloc region (NTAMS will move to top() and the objects
3522 // originally below it will be grayed). All objects now marked in
3523 // the region are explicitly grayed, if below the global finger,
3524 // and we do not need in fact to scan anything else. So, we simply
3525 // set _finger to be limit to ensure that the bitmap iteration
3526 // doesn't do anything.
3527 _finger = limit;
3528 }
3529
3530 _region_limit = limit;
3531 }
3532
3533 void CMTask::giveup_current_region() {
3534 assert(_curr_region != NULL, "invariant");
3535 if (_cm->verbose_low()) {
3536 gclog_or_tty->print_cr("[%u] giving up region "PTR_FORMAT,
3537 _worker_id, p2i(_curr_region));
3538 }
3539 clear_region_fields();
3540 }
3541
3542 void CMTask::clear_region_fields() {
3543 // Values for these three fields that indicate that we're not
3544 // holding on to a region.
3545 _curr_region = NULL;
3546 _finger = NULL;
3547 _region_limit = NULL;
3548 }
3549
3550 void CMTask::set_cm_oop_closure(G1CMOopClosure* cm_oop_closure) {
3551 if (cm_oop_closure == NULL) {
3552 assert(_cm_oop_closure != NULL, "invariant");
3553 } else {
3554 assert(_cm_oop_closure == NULL, "invariant");
3555 }
3556 _cm_oop_closure = cm_oop_closure;
3557 }
3558
3559 void CMTask::reset(CMBitMap* nextMarkBitMap) {
3560 guarantee(nextMarkBitMap != NULL, "invariant");
3561
3562 if (_cm->verbose_low()) {
3563 gclog_or_tty->print_cr("[%u] resetting", _worker_id);
3564 }
3565
3566 _nextMarkBitMap = nextMarkBitMap;
3567 clear_region_fields();
3568
3569 _calls = 0;
3570 _elapsed_time_ms = 0.0;
3571 _termination_time_ms = 0.0;
3572 _termination_start_time_ms = 0.0;
3573
3574 #if _MARKING_STATS_
3575 _aborted = 0;
3576 _aborted_overflow = 0;
3577 _aborted_cm_aborted = 0;
3578 _aborted_yield = 0;
3579 _aborted_timed_out = 0;
3580 _aborted_satb = 0;
3581 _aborted_termination = 0;
3582 _steal_attempts = 0;
3583 _steals = 0;
3584 _local_pushes = 0;
3585 _local_pops = 0;
3586 _local_max_size = 0;
3587 _objs_scanned = 0;
3588 _stale_humongous_queue_entries = 0;
3589 _global_pushes = 0;
3590 _global_pops = 0;
3591 _global_max_size = 0;
3592 _global_transfers_to = 0;
3593 _global_transfers_from = 0;
3594 _regions_claimed = 0;
3595 _objs_found_on_bitmap = 0;
3596 _satb_buffers_processed = 0;
3597 #endif // _MARKING_STATS_
3598 }
3599
3600 bool CMTask::should_exit_termination() {
3601 regular_clock_call();
3602 // This is called when we are in the termination protocol. We should
3603 // quit if, for some reason, this task wants to abort or the global
3604 // stack is not empty (this means that we can get work from it).
3605 return !_cm->mark_stack_empty() || has_aborted();
3606 }
3607
3608 void CMTask::reached_limit() {
3609 assert(_words_scanned >= _words_scanned_limit ||
3610 _refs_reached >= _refs_reached_limit ,
3611 "shouldn't have been called otherwise");
3612 regular_clock_call();
3613 }
3614
3615 void CMTask::regular_clock_call() {
3616 if (has_aborted()) return;
3617
3618 // First, we need to recalculate the words scanned and refs reached
3619 // limits for the next clock call.
3620 recalculate_limits();
3621
3622 // During the regular clock call we do the following
3623
3624 // (1) If an overflow has been flagged, then we abort.
3625 if (_cm->has_overflown()) {
3626 set_has_aborted();
3627 return;
3628 }
3629
3630 // If we are not concurrent (i.e. we're doing remark) we don't need
3631 // to check anything else. The other steps are only needed during
3632 // the concurrent marking phase.
3633 if (!concurrent()) return;
3634
3635 // (2) If marking has been aborted for Full GC, then we also abort.
3636 if (_cm->has_aborted()) {
3637 set_has_aborted();
3638 statsOnly( ++_aborted_cm_aborted );
3639 return;
3640 }
3641
3642 double curr_time_ms = os::elapsedVTime() * 1000.0;
3643
3644 // (3) If marking stats are enabled, then we update the step history.
3645 #if _MARKING_STATS_
3646 if (_words_scanned >= _words_scanned_limit) {
3647 ++_clock_due_to_scanning;
3648 }
3649 if (_refs_reached >= _refs_reached_limit) {
3650 ++_clock_due_to_marking;
3651 }
3652
3653 double last_interval_ms = curr_time_ms - _interval_start_time_ms;
3654 _interval_start_time_ms = curr_time_ms;
3655 _all_clock_intervals_ms.add(last_interval_ms);
3656
3657 if (_cm->verbose_medium()) {
3658 gclog_or_tty->print_cr("[%u] regular clock, interval = %1.2lfms, "
3659 "scanned = "SIZE_FORMAT"%s, refs reached = "SIZE_FORMAT"%s",
3660 _worker_id, last_interval_ms,
3661 _words_scanned,
3662 (_words_scanned >= _words_scanned_limit) ? " (*)" : "",
3663 _refs_reached,
3664 (_refs_reached >= _refs_reached_limit) ? " (*)" : "");
3665 }
3666 #endif // _MARKING_STATS_
3667
3668 // (4) We check whether we should yield. If we have to, then we abort.
3669 if (SuspendibleThreadSet::should_yield()) {
3670 // We should yield. To do this we abort the task. The caller is
3671 // responsible for yielding.
3672 set_has_aborted();
3673 statsOnly( ++_aborted_yield );
3674 return;
3675 }
3676
3677 // (5) We check whether we've reached our time quota. If we have,
3678 // then we abort.
3679 double elapsed_time_ms = curr_time_ms - _start_time_ms;
3680 if (elapsed_time_ms > _time_target_ms) {
3681 set_has_aborted();
3682 _has_timed_out = true;
3683 statsOnly( ++_aborted_timed_out );
3684 return;
3685 }
3686
3687 // (6) Finally, we check whether there are enough completed STAB
3688 // buffers available for processing. If there are, we abort.
3689 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
3690 if (!_draining_satb_buffers && satb_mq_set.process_completed_buffers()) {
3691 if (_cm->verbose_low()) {
3692 gclog_or_tty->print_cr("[%u] aborting to deal with pending SATB buffers",
3693 _worker_id);
3694 }
3695 // we do need to process SATB buffers, we'll abort and restart
3696 // the marking task to do so
3697 set_has_aborted();
3698 statsOnly( ++_aborted_satb );
3699 return;
3700 }
3701 }
3702
3703 void CMTask::recalculate_limits() {
3704 _real_words_scanned_limit = _words_scanned + words_scanned_period;
3705 _words_scanned_limit = _real_words_scanned_limit;
3706
3707 _real_refs_reached_limit = _refs_reached + refs_reached_period;
3708 _refs_reached_limit = _real_refs_reached_limit;
3709 }
3710
3711 void CMTask::decrease_limits() {
3712 // This is called when we believe that we're going to do an infrequent
3713 // operation which will increase the per byte scanned cost (i.e. move
3714 // entries to/from the global stack). It basically tries to decrease the
3715 // scanning limit so that the clock is called earlier.
3716
3717 if (_cm->verbose_medium()) {
3718 gclog_or_tty->print_cr("[%u] decreasing limits", _worker_id);
3719 }
3720
3721 _words_scanned_limit = _real_words_scanned_limit -
3722 3 * words_scanned_period / 4;
3723 _refs_reached_limit = _real_refs_reached_limit -
3724 3 * refs_reached_period / 4;
3725 }
3726
3727 void CMTask::move_entries_to_global_stack() {
3728 // local array where we'll store the entries that will be popped
3729 // from the local queue
3730 oop buffer[global_stack_transfer_size];
3731
3732 int n = 0;
3733 oop obj;
3734 while (n < global_stack_transfer_size && _task_queue->pop_local(obj)) {
3735 buffer[n] = obj;
3736 ++n;
3737 }
3738
3739 if (n > 0) {
3740 // we popped at least one entry from the local queue
3741
3742 statsOnly( ++_global_transfers_to; _local_pops += n );
3743
3744 if (!_cm->mark_stack_push(buffer, n)) {
3745 if (_cm->verbose_low()) {
3746 gclog_or_tty->print_cr("[%u] aborting due to global stack overflow",
3747 _worker_id);
3748 }
3749 set_has_aborted();
3750 } else {
3751 // the transfer was successful
3752
3753 if (_cm->verbose_medium()) {
3754 gclog_or_tty->print_cr("[%u] pushed %d entries to the global stack",
3755 _worker_id, n);
3756 }
3757 statsOnly( size_t tmp_size = _cm->mark_stack_size();
3758 if (tmp_size > _global_max_size) {
3759 _global_max_size = tmp_size;
3760 }
3761 _global_pushes += n );
3762 }
3763 }
3764
3765 // this operation was quite expensive, so decrease the limits
3766 decrease_limits();
3767 }
3768
3769 void CMTask::get_entries_from_global_stack() {
3770 // local array where we'll store the entries that will be popped
3771 // from the global stack.
3772 oop buffer[global_stack_transfer_size];
3773 int n;
3774 _cm->mark_stack_pop(buffer, global_stack_transfer_size, &n);
3775 assert(n <= global_stack_transfer_size,
3776 "we should not pop more than the given limit");
3777 if (n > 0) {
3778 // yes, we did actually pop at least one entry
3779
3780 statsOnly( ++_global_transfers_from; _global_pops += n );
3781 if (_cm->verbose_medium()) {
3782 gclog_or_tty->print_cr("[%u] popped %d entries from the global stack",
3783 _worker_id, n);
3784 }
3785 for (int i = 0; i < n; ++i) {
3786 bool success = _task_queue->push(buffer[i]);
3787 // We only call this when the local queue is empty or under a
3788 // given target limit. So, we do not expect this push to fail.
3789 assert(success, "invariant");
3790 }
3791
3792 statsOnly( size_t tmp_size = (size_t)_task_queue->size();
3793 if (tmp_size > _local_max_size) {
3794 _local_max_size = tmp_size;
3795 }
3796 _local_pushes += n );
3797 }
3798
3799 // this operation was quite expensive, so decrease the limits
3800 decrease_limits();
3801 }
3802
3803 void CMTask::drain_local_queue(bool partially) {
3804 if (has_aborted()) return;
3805
3806 // Decide what the target size is, depending whether we're going to
3807 // drain it partially (so that other tasks can steal if they run out
3808 // of things to do) or totally (at the very end).
3809 size_t target_size;
3810 if (partially) {
3811 target_size = MIN2((size_t)_task_queue->max_elems()/3, GCDrainStackTargetSize);
3812 } else {
3813 target_size = 0;
3814 }
3815
3816 if (_task_queue->size() > target_size) {
3817 if (_cm->verbose_high()) {
3818 gclog_or_tty->print_cr("[%u] draining local queue, target size = " SIZE_FORMAT,
3819 _worker_id, target_size);
3820 }
3821
3822 oop obj;
3823 bool ret = _task_queue->pop_local(obj);
3824 while (ret) {
3825 statsOnly( ++_local_pops );
3826
3827 if (_cm->verbose_high()) {
3828 gclog_or_tty->print_cr("[%u] popped "PTR_FORMAT, _worker_id,
3829 p2i((void*) obj));
3830 }
3831
3832 process_queue_entry(obj);
3833
3834 if (_task_queue->size() <= target_size || has_aborted()) {
3835 ret = false;
3836 } else {
3837 ret = _task_queue->pop_local(obj);
3838 }
3839 }
3840
3841 if (_cm->verbose_high()) {
3842 gclog_or_tty->print_cr("[%u] drained local queue, size = %u",
3843 _worker_id, _task_queue->size());
3844 }
3845 }
3846 }
3847
3848 void CMTask::drain_global_stack(bool partially) {
3849 if (has_aborted()) return;
3850
3851 // We have a policy to drain the local queue before we attempt to
3852 // drain the global stack.
3853 assert(partially || _task_queue->size() == 0, "invariant");
3854
3855 // Decide what the target size is, depending whether we're going to
3856 // drain it partially (so that other tasks can steal if they run out
3857 // of things to do) or totally (at the very end). Notice that,
3858 // because we move entries from the global stack in chunks or
3859 // because another task might be doing the same, we might in fact
3860 // drop below the target. But, this is not a problem.
3861 size_t target_size;
3862 if (partially) {
3863 target_size = _cm->partial_mark_stack_size_target();
3864 } else {
3865 target_size = 0;
3866 }
3867
3868 if (_cm->mark_stack_size() > target_size) {
3869 if (_cm->verbose_low()) {
3870 gclog_or_tty->print_cr("[%u] draining global_stack, target size " SIZE_FORMAT,
3871 _worker_id, target_size);
3872 }
3873
3874 while (!has_aborted() && _cm->mark_stack_size() > target_size) {
3875 get_entries_from_global_stack();
3876 drain_local_queue(partially);
3877 }
3878
3879 if (_cm->verbose_low()) {
3880 gclog_or_tty->print_cr("[%u] drained global stack, size = " SIZE_FORMAT,
3881 _worker_id, _cm->mark_stack_size());
3882 }
3883 }
3884 }
3885
3886 // SATB Queue has several assumptions on whether to call the par or
3887 // non-par versions of the methods. this is why some of the code is
3888 // replicated. We should really get rid of the single-threaded version
3889 // of the code to simplify things.
3890 void CMTask::drain_satb_buffers() {
3891 if (has_aborted()) return;
3892
3893 // We set this so that the regular clock knows that we're in the
3894 // middle of draining buffers and doesn't set the abort flag when it
3895 // notices that SATB buffers are available for draining. It'd be
3896 // very counter productive if it did that. :-)
3897 _draining_satb_buffers = true;
3898
3899 CMObjectClosure oc(this);
3900 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
3901 satb_mq_set.set_closure(_worker_id, &oc);
3902
3903 // This keeps claiming and applying the closure to completed buffers
3904 // until we run out of buffers or we need to abort.
3905 while (!has_aborted() &&
3906 satb_mq_set.apply_closure_to_completed_buffer(_worker_id)) {
3907 if (_cm->verbose_medium()) {
3908 gclog_or_tty->print_cr("[%u] processed an SATB buffer", _worker_id);
3909 }
3910 statsOnly( ++_satb_buffers_processed );
3911 regular_clock_call();
3912 }
3913
3914 _draining_satb_buffers = false;
3915
3916 assert(has_aborted() ||
3917 concurrent() ||
3918 satb_mq_set.completed_buffers_num() == 0, "invariant");
3919
3920 satb_mq_set.set_closure(_worker_id, NULL);
3921
3922 // again, this was a potentially expensive operation, decrease the
3923 // limits to get the regular clock call early
3924 decrease_limits();
3925 }
3926
3927 void CMTask::print_stats() {
3928 gclog_or_tty->print_cr("Marking Stats, task = %u, calls = %d",
3929 _worker_id, _calls);
3930 gclog_or_tty->print_cr(" Elapsed time = %1.2lfms, Termination time = %1.2lfms",
3931 _elapsed_time_ms, _termination_time_ms);
3932 gclog_or_tty->print_cr(" Step Times (cum): num = %d, avg = %1.2lfms, sd = %1.2lfms",
3933 _step_times_ms.num(), _step_times_ms.avg(),
3934 _step_times_ms.sd());
3935 gclog_or_tty->print_cr(" max = %1.2lfms, total = %1.2lfms",
3936 _step_times_ms.maximum(), _step_times_ms.sum());
3937
3938 #if _MARKING_STATS_
3939 gclog_or_tty->print_cr(" Clock Intervals (cum): num = %d, avg = %1.2lfms, sd = %1.2lfms",
3940 _all_clock_intervals_ms.num(), _all_clock_intervals_ms.avg(),
3941 _all_clock_intervals_ms.sd());
3942 gclog_or_tty->print_cr(" max = %1.2lfms, total = %1.2lfms",
3943 _all_clock_intervals_ms.maximum(),
3944 _all_clock_intervals_ms.sum());
3945 gclog_or_tty->print_cr(" Clock Causes (cum): scanning = " SIZE_FORMAT ", marking = " SIZE_FORMAT,
3946 _clock_due_to_scanning, _clock_due_to_marking);
3947 gclog_or_tty->print_cr(" Objects: scanned = " SIZE_FORMAT ", found on the bitmap = " SIZE_FORMAT,
3948 _objs_scanned, _objs_found_on_bitmap);
3949 gclog_or_tty->print_cr(" Local Queue: pushes = " SIZE_FORMAT ", pops = " SIZE_FORMAT ", max size = " SIZE_FORMAT,
3950 _local_pushes, _local_pops, _local_max_size);
3951 gclog_or_tty->print_cr(" Global Stack: pushes = " SIZE_FORMAT ", pops = " SIZE_FORMAT ", max size = " SIZE_FORMAT,
3952 _global_pushes, _global_pops, _global_max_size);
3953 gclog_or_tty->print_cr(" transfers to = " SIZE_FORMAT ", transfers from = " SIZE_FORMAT,
3954 _global_transfers_to,_global_transfers_from);
3955 gclog_or_tty->print_cr(" Regions: claimed = " SIZE_FORMAT, _regions_claimed);
3956 gclog_or_tty->print_cr(" SATB buffers: processed = " SIZE_FORMAT, _satb_buffers_processed);
3957 gclog_or_tty->print_cr(" Steals: attempts = " SIZE_FORMAT ", successes = " SIZE_FORMAT,
3958 _steal_attempts, _steals);
3959 gclog_or_tty->print_cr(" Skipped stale humongous queue entries = " SIZE_FORMAT,
3960 _stale_humongous_queue_entries);
3961 gclog_or_tty->print_cr(" Aborted: " SIZE_FORMAT ", due to", _aborted);
3962 gclog_or_tty->print_cr(" overflow: " SIZE_FORMAT ", global abort: " SIZE_FORMAT ", yield: " SIZE_FORMAT,
3963 _aborted_overflow, _aborted_cm_aborted, _aborted_yield);
3964 gclog_or_tty->print_cr(" time out: " SIZE_FORMAT ", SATB: " SIZE_FORMAT ", termination: " SIZE_FORMAT,
3965 _aborted_timed_out, _aborted_satb, _aborted_termination);
3966 #endif // _MARKING_STATS_
3967 }
3968
3969 /*****************************************************************************
3970
3971 The do_marking_step(time_target_ms, ...) method is the building
3972 block of the parallel marking framework. It can be called in parallel
3973 with other invocations of do_marking_step() on different tasks
3974 (but only one per task, obviously) and concurrently with the
3975 mutator threads, or during remark, hence it eliminates the need
3976 for two versions of the code. When called during remark, it will
3977 pick up from where the task left off during the concurrent marking
3978 phase. Interestingly, tasks are also claimable during evacuation
3979 pauses too, since do_marking_step() ensures that it aborts before
3980 it needs to yield.
3981
3982 The data structures that it uses to do marking work are the
3983 following:
3984
3985 (1) Marking Bitmap. If there are gray objects that appear only
3986 on the bitmap (this happens either when dealing with an overflow
3987 or when the initial marking phase has simply marked the roots
3988 and didn't push them on the stack), then tasks claim heap
3989 regions whose bitmap they then scan to find gray objects. A
3990 global finger indicates where the end of the last claimed region
3991 is. A local finger indicates how far into the region a task has
3992 scanned. The two fingers are used to determine how to gray an
3993 object (i.e. whether simply marking it is OK, as it will be
3994 visited by a task in the future, or whether it needs to be also
3995 pushed on a stack).
3996
3997 (2) Local Queue. The local queue of the task which is accessed
3998 reasonably efficiently by the task. Other tasks can steal from
3999 it when they run out of work. Throughout the marking phase, a
4000 task attempts to keep its local queue short but not totally
4001 empty, so that entries are available for stealing by other
4002 tasks. Only when there is no more work, a task will totally
4003 drain its local queue.
4004
4005 (3) Global Mark Stack. This handles local queue overflow. During
4006 marking only sets of entries are moved between it and the local
4007 queues, as access to it requires a mutex and more fine-grain
4008 interaction with it which might cause contention. If it
4009 overflows, then the marking phase should restart and iterate
4010 over the bitmap to identify gray objects. Throughout the marking
4011 phase, tasks attempt to keep the global mark stack at a small
4012 length but not totally empty, so that entries are available for
4013 popping by other tasks. Only when there is no more work, tasks
4014 will totally drain the global mark stack.
4015
4016 (4) SATB Buffer Queue. This is where completed SATB buffers are
4017 made available. Buffers are regularly removed from this queue
4018 and scanned for roots, so that the queue doesn't get too
4019 long. During remark, all completed buffers are processed, as
4020 well as the filled in parts of any uncompleted buffers.
4021
4022 The do_marking_step() method tries to abort when the time target
4023 has been reached. There are a few other cases when the
4024 do_marking_step() method also aborts:
4025
4026 (1) When the marking phase has been aborted (after a Full GC).
4027
4028 (2) When a global overflow (on the global stack) has been
4029 triggered. Before the task aborts, it will actually sync up with
4030 the other tasks to ensure that all the marking data structures
4031 (local queues, stacks, fingers etc.) are re-initialized so that
4032 when do_marking_step() completes, the marking phase can
4033 immediately restart.
4034
4035 (3) When enough completed SATB buffers are available. The
4036 do_marking_step() method only tries to drain SATB buffers right
4037 at the beginning. So, if enough buffers are available, the
4038 marking step aborts and the SATB buffers are processed at
4039 the beginning of the next invocation.
4040
4041 (4) To yield. when we have to yield then we abort and yield
4042 right at the end of do_marking_step(). This saves us from a lot
4043 of hassle as, by yielding we might allow a Full GC. If this
4044 happens then objects will be compacted underneath our feet, the
4045 heap might shrink, etc. We save checking for this by just
4046 aborting and doing the yield right at the end.
4047
4048 From the above it follows that the do_marking_step() method should
4049 be called in a loop (or, otherwise, regularly) until it completes.
4050
4051 If a marking step completes without its has_aborted() flag being
4052 true, it means it has completed the current marking phase (and
4053 also all other marking tasks have done so and have all synced up).
4054
4055 A method called regular_clock_call() is invoked "regularly" (in
4056 sub ms intervals) throughout marking. It is this clock method that
4057 checks all the abort conditions which were mentioned above and
4058 decides when the task should abort. A work-based scheme is used to
4059 trigger this clock method: when the number of object words the
4060 marking phase has scanned or the number of references the marking
4061 phase has visited reach a given limit. Additional invocations to
4062 the method clock have been planted in a few other strategic places
4063 too. The initial reason for the clock method was to avoid calling
4064 vtime too regularly, as it is quite expensive. So, once it was in
4065 place, it was natural to piggy-back all the other conditions on it
4066 too and not constantly check them throughout the code.
4067
4068 If do_termination is true then do_marking_step will enter its
4069 termination protocol.
4070
4071 The value of is_serial must be true when do_marking_step is being
4072 called serially (i.e. by the VMThread) and do_marking_step should
4073 skip any synchronization in the termination and overflow code.
4074 Examples include the serial remark code and the serial reference
4075 processing closures.
4076
4077 The value of is_serial must be false when do_marking_step is
4078 being called by any of the worker threads in a work gang.
4079 Examples include the concurrent marking code (CMMarkingTask),
4080 the MT remark code, and the MT reference processing closures.
4081
4082 *****************************************************************************/
4083
4084 void CMTask::do_marking_step(double time_target_ms,
4085 bool do_termination,
4086 bool is_serial) {
4087 assert(time_target_ms >= 1.0, "minimum granularity is 1ms");
4088 assert(concurrent() == _cm->concurrent(), "they should be the same");
4089
4090 G1CollectorPolicy* g1_policy = _g1h->g1_policy();
4091 assert(_task_queues != NULL, "invariant");
4092 assert(_task_queue != NULL, "invariant");
4093 assert(_task_queues->queue(_worker_id) == _task_queue, "invariant");
4094
4095 assert(!_claimed,
4096 "only one thread should claim this task at any one time");
4097
4098 // OK, this doesn't safeguard again all possible scenarios, as it is
4099 // possible for two threads to set the _claimed flag at the same
4100 // time. But it is only for debugging purposes anyway and it will
4101 // catch most problems.
4102 _claimed = true;
4103
4104 _start_time_ms = os::elapsedVTime() * 1000.0;
4105 statsOnly( _interval_start_time_ms = _start_time_ms );
4106
4107 // If do_stealing is true then do_marking_step will attempt to
4108 // steal work from the other CMTasks. It only makes sense to
4109 // enable stealing when the termination protocol is enabled
4110 // and do_marking_step() is not being called serially.
4111 bool do_stealing = do_termination && !is_serial;
4112
4113 double diff_prediction_ms =
4114 g1_policy->get_new_prediction(&_marking_step_diffs_ms);
4115 _time_target_ms = time_target_ms - diff_prediction_ms;
4116
4117 // set up the variables that are used in the work-based scheme to
4118 // call the regular clock method
4119 _words_scanned = 0;
4120 _refs_reached = 0;
4121 recalculate_limits();
4122
4123 // clear all flags
4124 clear_has_aborted();
4125 _has_timed_out = false;
4126 _draining_satb_buffers = false;
4127
4128 ++_calls;
4129
4130 if (_cm->verbose_low()) {
4131 gclog_or_tty->print_cr("[%u] >>>>>>>>>> START, call = %d, "
4132 "target = %1.2lfms >>>>>>>>>>",
4133 _worker_id, _calls, _time_target_ms);
4134 }
4135
4136 // Set up the bitmap and oop closures. Anything that uses them is
4137 // eventually called from this method, so it is OK to allocate these
4138 // statically.
4139 CMBitMapClosure bitmap_closure(this, _cm, _nextMarkBitMap);
4140 G1CMOopClosure cm_oop_closure(_g1h, _cm, this);
4141 set_cm_oop_closure(&cm_oop_closure);
4142
4143 if (_cm->has_overflown()) {
4144 // This can happen if the mark stack overflows during a GC pause
4145 // and this task, after a yield point, restarts. We have to abort
4146 // as we need to get into the overflow protocol which happens
4147 // right at the end of this task.
4148 set_has_aborted();
4149 }
4150
4151 // First drain any available SATB buffers. After this, we will not
4152 // look at SATB buffers before the next invocation of this method.
4153 // If enough completed SATB buffers are queued up, the regular clock
4154 // will abort this task so that it restarts.
4155 drain_satb_buffers();
4156 // ...then partially drain the local queue and the global stack
4157 drain_local_queue(true);
4158 drain_global_stack(true);
4159
4160 do {
4161 if (!has_aborted() && _curr_region != NULL) {
4162 // This means that we're already holding on to a region.
4163 assert(_finger != NULL, "if region is not NULL, then the finger "
4164 "should not be NULL either");
4165
4166 // We might have restarted this task after an evacuation pause
4167 // which might have evacuated the region we're holding on to
4168 // underneath our feet. Let's read its limit again to make sure
4169 // that we do not iterate over a region of the heap that
4170 // contains garbage (update_region_limit() will also move
4171 // _finger to the start of the region if it is found empty).
4172 update_region_limit();
4173 // We will start from _finger not from the start of the region,
4174 // as we might be restarting this task after aborting half-way
4175 // through scanning this region. In this case, _finger points to
4176 // the address where we last found a marked object. If this is a
4177 // fresh region, _finger points to start().
4178 MemRegion mr = MemRegion(_finger, _region_limit);
4179
4180 if (_cm->verbose_low()) {
4181 gclog_or_tty->print_cr("[%u] we're scanning part "
4182 "["PTR_FORMAT", "PTR_FORMAT") "
4183 "of region "HR_FORMAT,
4184 _worker_id, p2i(_finger), p2i(_region_limit),
4185 HR_FORMAT_PARAMS(_curr_region));
4186 }
4187
4188 assert(!_curr_region->is_humongous() || mr.start() == _curr_region->bottom(),
4189 "humongous regions should go around loop once only");
4190
4191 // Some special cases:
4192 // If the memory region is empty, we can just give up the region.
4193 // If the current region is humongous then we only need to check
4194 // the bitmap for the bit associated with the start of the object,
4195 // scan the object if it's live, and give up the region.
4196 // Otherwise, let's iterate over the bitmap of the part of the region
4197 // that is left.
4198 // If the iteration is successful, give up the region.
4199 if (mr.is_empty()) {
4200 giveup_current_region();
4201 regular_clock_call();
4202 } else if (_curr_region->is_humongous() && mr.start() == _curr_region->bottom()) {
4203 if (_nextMarkBitMap->isMarked(mr.start())) {
4204 // The object is marked - apply the closure
4205 BitMap::idx_t offset = _nextMarkBitMap->heapWordToOffset(mr.start());
4206 bitmap_closure.do_bit(offset);
4207 }
4208 // Even if this task aborted while scanning the humongous object
4209 // we can (and should) give up the current region.
4210 giveup_current_region();
4211 regular_clock_call();
4212 } else if (_nextMarkBitMap->iterate(&bitmap_closure, mr)) {
4213 giveup_current_region();
4214 regular_clock_call();
4215 } else {
4216 assert(has_aborted(), "currently the only way to do so");
4217 // The only way to abort the bitmap iteration is to return
4218 // false from the do_bit() method. However, inside the
4219 // do_bit() method we move the _finger to point to the
4220 // object currently being looked at. So, if we bail out, we
4221 // have definitely set _finger to something non-null.
4222 assert(_finger != NULL, "invariant");
4223
4224 // Region iteration was actually aborted. So now _finger
4225 // points to the address of the object we last scanned. If we
4226 // leave it there, when we restart this task, we will rescan
4227 // the object. It is easy to avoid this. We move the finger by
4228 // enough to point to the next possible object header (the
4229 // bitmap knows by how much we need to move it as it knows its
4230 // granularity).
4231 assert(_finger < _region_limit, "invariant");
4232 HeapWord* new_finger = _nextMarkBitMap->nextObject(_finger);
4233 // Check if bitmap iteration was aborted while scanning the last object
4234 if (new_finger >= _region_limit) {
4235 giveup_current_region();
4236 } else {
4237 move_finger_to(new_finger);
4238 }
4239 }
4240 }
4241 // At this point we have either completed iterating over the
4242 // region we were holding on to, or we have aborted.
4243
4244 // We then partially drain the local queue and the global stack.
4245 // (Do we really need this?)
4246 drain_local_queue(true);
4247 drain_global_stack(true);
4248
4249 // Read the note on the claim_region() method on why it might
4250 // return NULL with potentially more regions available for
4251 // claiming and why we have to check out_of_regions() to determine
4252 // whether we're done or not.
4253 while (!has_aborted() && _curr_region == NULL && !_cm->out_of_regions()) {
4254 // We are going to try to claim a new region. We should have
4255 // given up on the previous one.
4256 // Separated the asserts so that we know which one fires.
4257 assert(_curr_region == NULL, "invariant");
4258 assert(_finger == NULL, "invariant");
4259 assert(_region_limit == NULL, "invariant");
4260 if (_cm->verbose_low()) {
4261 gclog_or_tty->print_cr("[%u] trying to claim a new region", _worker_id);
4262 }
4263 HeapRegion* claimed_region = _cm->claim_region(_worker_id);
4264 if (claimed_region != NULL) {
4265 // Yes, we managed to claim one
4266 statsOnly( ++_regions_claimed );
4267
4268 if (_cm->verbose_low()) {
4269 gclog_or_tty->print_cr("[%u] we successfully claimed "
4270 "region "PTR_FORMAT,
4271 _worker_id, p2i(claimed_region));
4272 }
4273
4274 setup_for_region(claimed_region);
4275 assert(_curr_region == claimed_region, "invariant");
4276 }
4277 // It is important to call the regular clock here. It might take
4278 // a while to claim a region if, for example, we hit a large
4279 // block of empty regions. So we need to call the regular clock
4280 // method once round the loop to make sure it's called
4281 // frequently enough.
4282 regular_clock_call();
4283 }
4284
4285 if (!has_aborted() && _curr_region == NULL) {
4286 assert(_cm->out_of_regions(),
4287 "at this point we should be out of regions");
4288 }
4289 } while ( _curr_region != NULL && !has_aborted());
4290
4291 if (!has_aborted()) {
4292 // We cannot check whether the global stack is empty, since other
4293 // tasks might be pushing objects to it concurrently.
4294 assert(_cm->out_of_regions(),
4295 "at this point we should be out of regions");
4296
4297 if (_cm->verbose_low()) {
4298 gclog_or_tty->print_cr("[%u] all regions claimed", _worker_id);
4299 }
4300
4301 // Try to reduce the number of available SATB buffers so that
4302 // remark has less work to do.
4303 drain_satb_buffers();
4304 }
4305
4306 // Since we've done everything else, we can now totally drain the
4307 // local queue and global stack.
4308 drain_local_queue(false);
4309 drain_global_stack(false);
4310
4311 // Attempt at work stealing from other task's queues.
4312 if (do_stealing && !has_aborted()) {
4313 // We have not aborted. This means that we have finished all that
4314 // we could. Let's try to do some stealing...
4315
4316 // We cannot check whether the global stack is empty, since other
4317 // tasks might be pushing objects to it concurrently.
4318 assert(_cm->out_of_regions() && _task_queue->size() == 0,
4319 "only way to reach here");
4320
4321 if (_cm->verbose_low()) {
4322 gclog_or_tty->print_cr("[%u] starting to steal", _worker_id);
4323 }
4324
4325 while (!has_aborted()) {
4326 oop obj;
4327 statsOnly( ++_steal_attempts );
4328
4329 if (_cm->try_stealing(_worker_id, &_hash_seed, obj)) {
4330 if (_cm->verbose_medium()) {
4331 gclog_or_tty->print_cr("[%u] stolen "PTR_FORMAT" successfully",
4332 _worker_id, p2i((void*) obj));
4333 }
4334
4335 statsOnly( ++_steals );
4336 process_queue_entry(obj);
4337
4338 // And since we're towards the end, let's totally drain the
4339 // local queue and global stack.
4340 drain_local_queue(false);
4341 drain_global_stack(false);
4342 } else {
4343 break;
4344 }
4345 }
4346 }
4347
4348 // If we are about to wrap up and go into termination, check if we
4349 // should raise the overflow flag.
4350 if (do_termination && !has_aborted()) {
4351 if (_cm->force_overflow()->should_force()) {
4352 _cm->set_has_overflown();
4353 regular_clock_call();
4354 }
4355 }
4356
4357 // We still haven't aborted. Now, let's try to get into the
4358 // termination protocol.
4359 if (do_termination && !has_aborted()) {
4360 // We cannot check whether the global stack is empty, since other
4361 // tasks might be concurrently pushing objects on it.
4362 // Separated the asserts so that we know which one fires.
4363 assert(_cm->out_of_regions(), "only way to reach here");
4364 assert(_task_queue->size() == 0, "only way to reach here");
4365
4366 if (_cm->verbose_low()) {
4367 gclog_or_tty->print_cr("[%u] starting termination protocol", _worker_id);
4368 }
4369
4370 _termination_start_time_ms = os::elapsedVTime() * 1000.0;
4371
4372 // The CMTask class also extends the TerminatorTerminator class,
4373 // hence its should_exit_termination() method will also decide
4374 // whether to exit the termination protocol or not.
4375 bool finished = (is_serial ||
4376 _cm->terminator()->offer_termination(this));
4377 double termination_end_time_ms = os::elapsedVTime() * 1000.0;
4378 _termination_time_ms +=
4379 termination_end_time_ms - _termination_start_time_ms;
4380
4381 if (finished) {
4382 // We're all done.
4383
4384 if (_worker_id == 0) {
4385 // let's allow task 0 to do this
4386 if (concurrent()) {
4387 assert(_cm->concurrent_marking_in_progress(), "invariant");
4388 // we need to set this to false before the next
4389 // safepoint. This way we ensure that the marking phase
4390 // doesn't observe any more heap expansions.
4391 _cm->clear_concurrent_marking_in_progress();
4392 }
4393 }
4394
4395 // We can now guarantee that the global stack is empty, since
4396 // all other tasks have finished. We separated the guarantees so
4397 // that, if a condition is false, we can immediately find out
4398 // which one.
4399 guarantee(_cm->out_of_regions(), "only way to reach here");
4400 guarantee(_cm->mark_stack_empty(), "only way to reach here");
4401 guarantee(_task_queue->size() == 0, "only way to reach here");
4402 guarantee(!_cm->has_overflown(), "only way to reach here");
4403 guarantee(!_cm->mark_stack_overflow(), "only way to reach here");
4404
4405 if (_cm->verbose_low()) {
4406 gclog_or_tty->print_cr("[%u] all tasks terminated", _worker_id);
4407 }
4408 } else {
4409 // Apparently there's more work to do. Let's abort this task. It
4410 // will restart it and we can hopefully find more things to do.
4411
4412 if (_cm->verbose_low()) {
4413 gclog_or_tty->print_cr("[%u] apparently there is more work to do",
4414 _worker_id);
4415 }
4416
4417 set_has_aborted();
4418 statsOnly( ++_aborted_termination );
4419 }
4420 }
4421
4422 // Mainly for debugging purposes to make sure that a pointer to the
4423 // closure which was statically allocated in this frame doesn't
4424 // escape it by accident.
4425 set_cm_oop_closure(NULL);
4426 double end_time_ms = os::elapsedVTime() * 1000.0;
4427 double elapsed_time_ms = end_time_ms - _start_time_ms;
4428 // Update the step history.
4429 _step_times_ms.add(elapsed_time_ms);
4430
4431 if (has_aborted()) {
4432 // The task was aborted for some reason.
4433
4434 statsOnly( ++_aborted );
4435
4436 if (_has_timed_out) {
4437 double diff_ms = elapsed_time_ms - _time_target_ms;
4438 // Keep statistics of how well we did with respect to hitting
4439 // our target only if we actually timed out (if we aborted for
4440 // other reasons, then the results might get skewed).
4441 _marking_step_diffs_ms.add(diff_ms);
4442 }
4443
4444 if (_cm->has_overflown()) {
4445 // This is the interesting one. We aborted because a global
4446 // overflow was raised. This means we have to restart the
4447 // marking phase and start iterating over regions. However, in
4448 // order to do this we have to make sure that all tasks stop
4449 // what they are doing and re-initialize in a safe manner. We
4450 // will achieve this with the use of two barrier sync points.
4451
4452 if (_cm->verbose_low()) {
4453 gclog_or_tty->print_cr("[%u] detected overflow", _worker_id);
4454 }
4455
4456 if (!is_serial) {
4457 // We only need to enter the sync barrier if being called
4458 // from a parallel context
4459 _cm->enter_first_sync_barrier(_worker_id);
4460
4461 // When we exit this sync barrier we know that all tasks have
4462 // stopped doing marking work. So, it's now safe to
4463 // re-initialize our data structures. At the end of this method,
4464 // task 0 will clear the global data structures.
4465 }
4466
4467 statsOnly( ++_aborted_overflow );
4468
4469 // We clear the local state of this task...
4470 clear_region_fields();
4471
4472 if (!is_serial) {
4473 // ...and enter the second barrier.
4474 _cm->enter_second_sync_barrier(_worker_id);
4475 }
4476 // At this point, if we're during the concurrent phase of
4477 // marking, everything has been re-initialized and we're
4478 // ready to restart.
4479 }
4480
4481 if (_cm->verbose_low()) {
4482 gclog_or_tty->print_cr("[%u] <<<<<<<<<< ABORTING, target = %1.2lfms, "
4483 "elapsed = %1.2lfms <<<<<<<<<<",
4484 _worker_id, _time_target_ms, elapsed_time_ms);
4485 if (_cm->has_aborted()) {
4486 gclog_or_tty->print_cr("[%u] ========== MARKING ABORTED ==========",
4487 _worker_id);
4488 }
4489 }
4490 } else {
4491 if (_cm->verbose_low()) {
4492 gclog_or_tty->print_cr("[%u] <<<<<<<<<< FINISHED, target = %1.2lfms, "
4493 "elapsed = %1.2lfms <<<<<<<<<<",
4494 _worker_id, _time_target_ms, elapsed_time_ms);
4495 }
4496 }
4497
4498 _claimed = false;
4499 }
4500
4501 CMTask::CMTask(uint worker_id,
4502 ConcurrentMark* cm,
4503 size_t* marked_bytes,
4504 BitMap* card_bm,
4505 CMTaskQueue* task_queue,
4506 CMTaskQueueSet* task_queues)
4507 : _g1h(G1CollectedHeap::heap()),
4508 _worker_id(worker_id), _cm(cm),
4509 _claimed(false),
4510 _nextMarkBitMap(NULL), _hash_seed(17),
4511 _task_queue(task_queue),
4512 _task_queues(task_queues),
4513 _cm_oop_closure(NULL),
4514 _marked_bytes_array(marked_bytes),
4515 _card_bm(card_bm) {
4516 guarantee(task_queue != NULL, "invariant");
4517 guarantee(task_queues != NULL, "invariant");
4518
4519 statsOnly( _clock_due_to_scanning = 0;
4520 _clock_due_to_marking = 0 );
4521
4522 _marking_step_diffs_ms.add(0.5);
4523 }
4524
4525 // These are formatting macros that are used below to ensure
4526 // consistent formatting. The *_H_* versions are used to format the
4527 // header for a particular value and they should be kept consistent
4528 // with the corresponding macro. Also note that most of the macros add
4529 // the necessary white space (as a prefix) which makes them a bit
4530 // easier to compose.
4531
4532 // All the output lines are prefixed with this string to be able to
4533 // identify them easily in a large log file.
4534 #define G1PPRL_LINE_PREFIX "###"
4535
4536 #define G1PPRL_ADDR_BASE_FORMAT " "PTR_FORMAT"-"PTR_FORMAT
4537 #ifdef _LP64
4538 #define G1PPRL_ADDR_BASE_H_FORMAT " %37s"
4539 #else // _LP64
4540 #define G1PPRL_ADDR_BASE_H_FORMAT " %21s"
4541 #endif // _LP64
4542
4543 // For per-region info
4544 #define G1PPRL_TYPE_FORMAT " %-4s"
4545 #define G1PPRL_TYPE_H_FORMAT " %4s"
4546 #define G1PPRL_BYTE_FORMAT " "SIZE_FORMAT_W(9)
4547 #define G1PPRL_BYTE_H_FORMAT " %9s"
4548 #define G1PPRL_DOUBLE_FORMAT " %14.1f"
4549 #define G1PPRL_DOUBLE_H_FORMAT " %14s"
4550
4551 // For summary info
4552 #define G1PPRL_SUM_ADDR_FORMAT(tag) " "tag":"G1PPRL_ADDR_BASE_FORMAT
4553 #define G1PPRL_SUM_BYTE_FORMAT(tag) " "tag": "SIZE_FORMAT
4554 #define G1PPRL_SUM_MB_FORMAT(tag) " "tag": %1.2f MB"
4555 #define G1PPRL_SUM_MB_PERC_FORMAT(tag) G1PPRL_SUM_MB_FORMAT(tag)" / %1.2f %%"
4556
4557 G1PrintRegionLivenessInfoClosure::
4558 G1PrintRegionLivenessInfoClosure(outputStream* out, const char* phase_name)
4559 : _out(out),
4560 _total_used_bytes(0), _total_capacity_bytes(0),
4561 _total_prev_live_bytes(0), _total_next_live_bytes(0),
4562 _hum_used_bytes(0), _hum_capacity_bytes(0),
4563 _hum_prev_live_bytes(0), _hum_next_live_bytes(0),
4564 _total_remset_bytes(0), _total_strong_code_roots_bytes(0) {
4565 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4566 MemRegion g1_reserved = g1h->g1_reserved();
4567 double now = os::elapsedTime();
4568
4569 // Print the header of the output.
4570 _out->cr();
4571 _out->print_cr(G1PPRL_LINE_PREFIX" PHASE %s @ %1.3f", phase_name, now);
4572 _out->print_cr(G1PPRL_LINE_PREFIX" HEAP"
4573 G1PPRL_SUM_ADDR_FORMAT("reserved")
4574 G1PPRL_SUM_BYTE_FORMAT("region-size"),
4575 p2i(g1_reserved.start()), p2i(g1_reserved.end()),
4576 HeapRegion::GrainBytes);
4577 _out->print_cr(G1PPRL_LINE_PREFIX);
4578 _out->print_cr(G1PPRL_LINE_PREFIX
4579 G1PPRL_TYPE_H_FORMAT
4580 G1PPRL_ADDR_BASE_H_FORMAT
4581 G1PPRL_BYTE_H_FORMAT
4582 G1PPRL_BYTE_H_FORMAT
4583 G1PPRL_BYTE_H_FORMAT
4584 G1PPRL_DOUBLE_H_FORMAT
4585 G1PPRL_BYTE_H_FORMAT
4586 G1PPRL_BYTE_H_FORMAT,
4587 "type", "address-range",
4588 "used", "prev-live", "next-live", "gc-eff",
4589 "remset", "code-roots");
4590 _out->print_cr(G1PPRL_LINE_PREFIX
4591 G1PPRL_TYPE_H_FORMAT
4592 G1PPRL_ADDR_BASE_H_FORMAT
4593 G1PPRL_BYTE_H_FORMAT
4594 G1PPRL_BYTE_H_FORMAT
4595 G1PPRL_BYTE_H_FORMAT
4596 G1PPRL_DOUBLE_H_FORMAT
4597 G1PPRL_BYTE_H_FORMAT
4598 G1PPRL_BYTE_H_FORMAT,
4599 "", "",
4600 "(bytes)", "(bytes)", "(bytes)", "(bytes/ms)",
4601 "(bytes)", "(bytes)");
4602 }
4603
4604 // It takes as a parameter a reference to one of the _hum_* fields, it
4605 // deduces the corresponding value for a region in a humongous region
4606 // series (either the region size, or what's left if the _hum_* field
4607 // is < the region size), and updates the _hum_* field accordingly.
4608 size_t G1PrintRegionLivenessInfoClosure::get_hum_bytes(size_t* hum_bytes) {
4609 size_t bytes = 0;
4610 // The > 0 check is to deal with the prev and next live bytes which
4611 // could be 0.
4612 if (*hum_bytes > 0) {
4613 bytes = MIN2(HeapRegion::GrainBytes, *hum_bytes);
4614 *hum_bytes -= bytes;
4615 }
4616 return bytes;
4617 }
4618
4619 // It deduces the values for a region in a humongous region series
4620 // from the _hum_* fields and updates those accordingly. It assumes
4621 // that that _hum_* fields have already been set up from the "starts
4622 // humongous" region and we visit the regions in address order.
4623 void G1PrintRegionLivenessInfoClosure::get_hum_bytes(size_t* used_bytes,
4624 size_t* capacity_bytes,
4625 size_t* prev_live_bytes,
4626 size_t* next_live_bytes) {
4627 assert(_hum_used_bytes > 0 && _hum_capacity_bytes > 0, "pre-condition");
4628 *used_bytes = get_hum_bytes(&_hum_used_bytes);
4629 *capacity_bytes = get_hum_bytes(&_hum_capacity_bytes);
4630 *prev_live_bytes = get_hum_bytes(&_hum_prev_live_bytes);
4631 *next_live_bytes = get_hum_bytes(&_hum_next_live_bytes);
4632 }
4633
4634 bool G1PrintRegionLivenessInfoClosure::doHeapRegion(HeapRegion* r) {
4635 const char* type = r->get_type_str();
4636 HeapWord* bottom = r->bottom();
4637 HeapWord* end = r->end();
4638 size_t capacity_bytes = r->capacity();
4639 size_t used_bytes = r->used();
4640 size_t prev_live_bytes = r->live_bytes();
4641 size_t next_live_bytes = r->next_live_bytes();
4642 double gc_eff = r->gc_efficiency();
4643 size_t remset_bytes = r->rem_set()->mem_size();
4644 size_t strong_code_roots_bytes = r->rem_set()->strong_code_roots_mem_size();
4645
4646 if (r->is_starts_humongous()) {
4647 assert(_hum_used_bytes == 0 && _hum_capacity_bytes == 0 &&
4648 _hum_prev_live_bytes == 0 && _hum_next_live_bytes == 0,
4649 "they should have been zeroed after the last time we used them");
4650 // Set up the _hum_* fields.
4651 _hum_capacity_bytes = capacity_bytes;
4652 _hum_used_bytes = used_bytes;
4653 _hum_prev_live_bytes = prev_live_bytes;
4654 _hum_next_live_bytes = next_live_bytes;
4655 get_hum_bytes(&used_bytes, &capacity_bytes,
4656 &prev_live_bytes, &next_live_bytes);
4657 end = bottom + HeapRegion::GrainWords;
4658 } else if (r->is_continues_humongous()) {
4659 get_hum_bytes(&used_bytes, &capacity_bytes,
4660 &prev_live_bytes, &next_live_bytes);
4661 assert(end == bottom + HeapRegion::GrainWords, "invariant");
4662 }
4663
4664 _total_used_bytes += used_bytes;
4665 _total_capacity_bytes += capacity_bytes;
4666 _total_prev_live_bytes += prev_live_bytes;
4667 _total_next_live_bytes += next_live_bytes;
4668 _total_remset_bytes += remset_bytes;
4669 _total_strong_code_roots_bytes += strong_code_roots_bytes;
4670
4671 // Print a line for this particular region.
4672 _out->print_cr(G1PPRL_LINE_PREFIX
4673 G1PPRL_TYPE_FORMAT
4674 G1PPRL_ADDR_BASE_FORMAT
4675 G1PPRL_BYTE_FORMAT
4676 G1PPRL_BYTE_FORMAT
4677 G1PPRL_BYTE_FORMAT
4678 G1PPRL_DOUBLE_FORMAT
4679 G1PPRL_BYTE_FORMAT
4680 G1PPRL_BYTE_FORMAT,
4681 type, p2i(bottom), p2i(end),
4682 used_bytes, prev_live_bytes, next_live_bytes, gc_eff,
4683 remset_bytes, strong_code_roots_bytes);
4684
4685 return false;
4686 }
4687
4688 G1PrintRegionLivenessInfoClosure::~G1PrintRegionLivenessInfoClosure() {
4689 // add static memory usages to remembered set sizes
4690 _total_remset_bytes += HeapRegionRemSet::fl_mem_size() + HeapRegionRemSet::static_mem_size();
4691 // Print the footer of the output.
4692 _out->print_cr(G1PPRL_LINE_PREFIX);
4693 _out->print_cr(G1PPRL_LINE_PREFIX
4694 " SUMMARY"
4695 G1PPRL_SUM_MB_FORMAT("capacity")
4696 G1PPRL_SUM_MB_PERC_FORMAT("used")
4697 G1PPRL_SUM_MB_PERC_FORMAT("prev-live")
4698 G1PPRL_SUM_MB_PERC_FORMAT("next-live")
4699 G1PPRL_SUM_MB_FORMAT("remset")
4700 G1PPRL_SUM_MB_FORMAT("code-roots"),
4701 bytes_to_mb(_total_capacity_bytes),
4702 bytes_to_mb(_total_used_bytes),
4703 perc(_total_used_bytes, _total_capacity_bytes),
4704 bytes_to_mb(_total_prev_live_bytes),
4705 perc(_total_prev_live_bytes, _total_capacity_bytes),
4706 bytes_to_mb(_total_next_live_bytes),
4707 perc(_total_next_live_bytes, _total_capacity_bytes),
4708 bytes_to_mb(_total_remset_bytes),
4709 bytes_to_mb(_total_strong_code_roots_bytes));
4710 _out->cr();
4711 }