1 /*
2 * Copyright (c) 2001, 2014, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/symbolTable.hpp"
27 #include "code/codeCache.hpp"
28 #include "gc_implementation/g1/concurrentMark.inline.hpp"
29 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
30 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
31 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
32 #include "gc_implementation/g1/g1ErgoVerbose.hpp"
33 #include "gc_implementation/g1/g1Log.hpp"
34 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
35 #include "gc_implementation/g1/g1RemSet.hpp"
36 #include "gc_implementation/g1/heapRegion.inline.hpp"
37 #include "gc_implementation/g1/heapRegionManager.inline.hpp"
38 #include "gc_implementation/g1/heapRegionRemSet.hpp"
39 #include "gc_implementation/g1/heapRegionSet.inline.hpp"
40 #include "gc_implementation/shared/vmGCOperations.hpp"
41 #include "gc_implementation/shared/gcTimer.hpp"
42 #include "gc_implementation/shared/gcTrace.hpp"
43 #include "gc_implementation/shared/gcTraceTime.hpp"
44 #include "memory/allocation.hpp"
45 #include "memory/genOopClosures.inline.hpp"
46 #include "memory/referencePolicy.hpp"
47 #include "memory/resourceArea.hpp"
48 #include "oops/oop.inline.hpp"
49 #include "runtime/handles.inline.hpp"
50 #include "runtime/java.hpp"
51 #include "runtime/atomic.inline.hpp"
52 #include "runtime/prefetch.inline.hpp"
53 #include "services/memTracker.hpp"
54
55 // Concurrent marking bit map wrapper
56
57 CMBitMapRO::CMBitMapRO(int shifter) :
58 _bm(),
59 _shifter(shifter) {
60 _bmStartWord = 0;
61 _bmWordSize = 0;
62 }
63
64 HeapWord* CMBitMapRO::getNextMarkedWordAddress(const HeapWord* addr,
65 const HeapWord* limit) const {
66 // First we must round addr *up* to a possible object boundary.
67 addr = (HeapWord*)align_size_up((intptr_t)addr,
68 HeapWordSize << _shifter);
69 size_t addrOffset = heapWordToOffset(addr);
70 if (limit == NULL) {
71 limit = _bmStartWord + _bmWordSize;
72 }
73 size_t limitOffset = heapWordToOffset(limit);
74 size_t nextOffset = _bm.get_next_one_offset(addrOffset, limitOffset);
75 HeapWord* nextAddr = offsetToHeapWord(nextOffset);
76 assert(nextAddr >= addr, "get_next_one postcondition");
77 assert(nextAddr == limit || isMarked(nextAddr),
78 "get_next_one postcondition");
79 return nextAddr;
80 }
81
82 HeapWord* CMBitMapRO::getNextUnmarkedWordAddress(const HeapWord* addr,
83 const HeapWord* limit) const {
84 size_t addrOffset = heapWordToOffset(addr);
85 if (limit == NULL) {
86 limit = _bmStartWord + _bmWordSize;
87 }
88 size_t limitOffset = heapWordToOffset(limit);
89 size_t nextOffset = _bm.get_next_zero_offset(addrOffset, limitOffset);
90 HeapWord* nextAddr = offsetToHeapWord(nextOffset);
91 assert(nextAddr >= addr, "get_next_one postcondition");
92 assert(nextAddr == limit || !isMarked(nextAddr),
93 "get_next_one postcondition");
94 return nextAddr;
95 }
96
97 int CMBitMapRO::heapWordDiffToOffsetDiff(size_t diff) const {
98 assert((diff & ((1 << _shifter) - 1)) == 0, "argument check");
99 return (int) (diff >> _shifter);
100 }
101
102 #ifndef PRODUCT
103 bool CMBitMapRO::covers(MemRegion heap_rs) const {
104 // assert(_bm.map() == _virtual_space.low(), "map inconsistency");
105 assert(((size_t)_bm.size() * ((size_t)1 << _shifter)) == _bmWordSize,
106 "size inconsistency");
107 return _bmStartWord == (HeapWord*)(heap_rs.start()) &&
108 _bmWordSize == heap_rs.word_size();
109 }
110 #endif
111
112 void CMBitMapRO::print_on_error(outputStream* st, const char* prefix) const {
113 _bm.print_on_error(st, prefix);
114 }
115
116 size_t CMBitMap::compute_size(size_t heap_size) {
117 return heap_size / mark_distance();
118 }
119
120 size_t CMBitMap::mark_distance() {
121 return MinObjAlignmentInBytes * BitsPerByte;
122 }
123
124 void CMBitMap::initialize(MemRegion heap, G1RegionToSpaceMapper* storage) {
125 _bmStartWord = heap.start();
126 _bmWordSize = heap.word_size();
127
128 _bm.set_map((BitMap::bm_word_t*) storage->reserved().start());
129 _bm.set_size(_bmWordSize >> _shifter);
130
131 storage->set_mapping_changed_listener(&_listener);
132 }
133
134 void CMBitMapMappingChangedListener::on_commit(uint start_region, size_t num_regions) {
135 // We need to clear the bitmap on commit, removing any existing information.
136 MemRegion mr(G1CollectedHeap::heap()->bottom_addr_for_region(start_region), num_regions * HeapRegion::GrainWords);
137 _bm->clearRange(mr);
138 }
139
140 // Closure used for clearing the given mark bitmap.
141 class ClearBitmapHRClosure : public HeapRegionClosure {
142 private:
143 ConcurrentMark* _cm;
144 CMBitMap* _bitmap;
145 bool _may_yield; // The closure may yield during iteration. If yielded, abort the iteration.
146 public:
147 ClearBitmapHRClosure(ConcurrentMark* cm, CMBitMap* bitmap, bool may_yield) : HeapRegionClosure(), _cm(cm), _bitmap(bitmap), _may_yield(may_yield) {
148 assert(!may_yield || cm != NULL, "CM must be non-NULL if this closure is expected to yield.");
149 }
150
151 virtual bool doHeapRegion(HeapRegion* r) {
152 size_t const chunk_size_in_words = M / HeapWordSize;
153
154 HeapWord* cur = r->bottom();
155 HeapWord* const end = r->end();
156
157 while (cur < end) {
158 MemRegion mr(cur, MIN2(cur + chunk_size_in_words, end));
159 _bitmap->clearRange(mr);
160
161 cur += chunk_size_in_words;
162
163 // Abort iteration if after yielding the marking has been aborted.
164 if (_may_yield && _cm->do_yield_check() && _cm->has_aborted()) {
165 return true;
166 }
167 // Repeat the asserts from before the start of the closure. We will do them
168 // as asserts here to minimize their overhead on the product. However, we
169 // will have them as guarantees at the beginning / end of the bitmap
170 // clearing to get some checking in the product.
171 assert(!_may_yield || _cm->cmThread()->during_cycle(), "invariant");
172 assert(!_may_yield || !G1CollectedHeap::heap()->mark_in_progress(), "invariant");
173 }
174
175 return false;
176 }
177 };
178
179 void CMBitMap::clearAll() {
180 ClearBitmapHRClosure cl(NULL, this, false /* may_yield */);
181 G1CollectedHeap::heap()->heap_region_iterate(&cl);
182 guarantee(cl.complete(), "Must have completed iteration.");
183 return;
184 }
185
186 void CMBitMap::markRange(MemRegion mr) {
187 mr.intersection(MemRegion(_bmStartWord, _bmWordSize));
188 assert(!mr.is_empty(), "unexpected empty region");
189 assert((offsetToHeapWord(heapWordToOffset(mr.end())) ==
190 ((HeapWord *) mr.end())),
191 "markRange memory region end is not card aligned");
192 // convert address range into offset range
193 _bm.at_put_range(heapWordToOffset(mr.start()),
194 heapWordToOffset(mr.end()), true);
195 }
196
197 void CMBitMap::clearRange(MemRegion mr) {
198 mr.intersection(MemRegion(_bmStartWord, _bmWordSize));
199 assert(!mr.is_empty(), "unexpected empty region");
200 // convert address range into offset range
201 _bm.at_put_range(heapWordToOffset(mr.start()),
202 heapWordToOffset(mr.end()), false);
203 }
204
205 MemRegion CMBitMap::getAndClearMarkedRegion(HeapWord* addr,
206 HeapWord* end_addr) {
207 HeapWord* start = getNextMarkedWordAddress(addr);
208 start = MIN2(start, end_addr);
209 HeapWord* end = getNextUnmarkedWordAddress(start);
210 end = MIN2(end, end_addr);
211 assert(start <= end, "Consistency check");
212 MemRegion mr(start, end);
213 if (!mr.is_empty()) {
214 clearRange(mr);
215 }
216 return mr;
217 }
218
219 CMMarkStack::CMMarkStack(ConcurrentMark* cm) :
220 _base(NULL), _cm(cm)
221 #ifdef ASSERT
222 , _drain_in_progress(false)
223 , _drain_in_progress_yields(false)
224 #endif
225 {}
226
227 bool CMMarkStack::allocate(size_t capacity) {
228 // allocate a stack of the requisite depth
229 ReservedSpace rs(ReservedSpace::allocation_align_size_up(capacity * sizeof(oop)));
230 if (!rs.is_reserved()) {
231 warning("ConcurrentMark MarkStack allocation failure");
232 return false;
233 }
234 MemTracker::record_virtual_memory_type((address)rs.base(), mtGC);
235 if (!_virtual_space.initialize(rs, rs.size())) {
236 warning("ConcurrentMark MarkStack backing store failure");
237 // Release the virtual memory reserved for the marking stack
238 rs.release();
239 return false;
240 }
241 assert(_virtual_space.committed_size() == rs.size(),
242 "Didn't reserve backing store for all of ConcurrentMark stack?");
243 _base = (oop*) _virtual_space.low();
244 setEmpty();
245 _capacity = (jint) capacity;
246 _saved_index = -1;
247 _should_expand = false;
248 NOT_PRODUCT(_max_depth = 0);
249 return true;
250 }
251
252 void CMMarkStack::expand() {
253 // Called, during remark, if we've overflown the marking stack during marking.
254 assert(isEmpty(), "stack should been emptied while handling overflow");
255 assert(_capacity <= (jint) MarkStackSizeMax, "stack bigger than permitted");
256 // Clear expansion flag
257 _should_expand = false;
258 if (_capacity == (jint) MarkStackSizeMax) {
259 if (PrintGCDetails && Verbose) {
260 gclog_or_tty->print_cr(" (benign) Can't expand marking stack capacity, at max size limit");
261 }
262 return;
263 }
264 // Double capacity if possible
265 jint new_capacity = MIN2(_capacity*2, (jint) MarkStackSizeMax);
266 // Do not give up existing stack until we have managed to
267 // get the double capacity that we desired.
268 ReservedSpace rs(ReservedSpace::allocation_align_size_up(new_capacity *
269 sizeof(oop)));
270 if (rs.is_reserved()) {
271 // Release the backing store associated with old stack
272 _virtual_space.release();
273 // Reinitialize virtual space for new stack
274 if (!_virtual_space.initialize(rs, rs.size())) {
275 fatal("Not enough swap for expanded marking stack capacity");
276 }
277 _base = (oop*)(_virtual_space.low());
278 _index = 0;
279 _capacity = new_capacity;
280 } else {
281 if (PrintGCDetails && Verbose) {
282 // Failed to double capacity, continue;
283 gclog_or_tty->print(" (benign) Failed to expand marking stack capacity from "
284 SIZE_FORMAT"K to " SIZE_FORMAT"K",
285 _capacity / K, new_capacity / K);
286 }
287 }
288 }
289
290 void CMMarkStack::set_should_expand() {
291 // If we're resetting the marking state because of an
292 // marking stack overflow, record that we should, if
293 // possible, expand the stack.
294 _should_expand = _cm->has_overflown();
295 }
296
297 CMMarkStack::~CMMarkStack() {
298 if (_base != NULL) {
299 _base = NULL;
300 _virtual_space.release();
301 }
302 }
303
304 void CMMarkStack::par_push(oop ptr) {
305 while (true) {
306 if (isFull()) {
307 _overflow = true;
308 return;
309 }
310 // Otherwise...
311 jint index = _index;
312 jint next_index = index+1;
313 jint res = Atomic::cmpxchg(next_index, &_index, index);
314 if (res == index) {
315 _base[index] = ptr;
316 // Note that we don't maintain this atomically. We could, but it
317 // doesn't seem necessary.
318 NOT_PRODUCT(_max_depth = MAX2(_max_depth, next_index));
319 return;
320 }
321 // Otherwise, we need to try again.
322 }
323 }
324
325 void CMMarkStack::par_adjoin_arr(oop* ptr_arr, int n) {
326 while (true) {
327 if (isFull()) {
328 _overflow = true;
329 return;
330 }
331 // Otherwise...
332 jint index = _index;
333 jint next_index = index + n;
334 if (next_index > _capacity) {
335 _overflow = true;
336 return;
337 }
338 jint res = Atomic::cmpxchg(next_index, &_index, index);
339 if (res == index) {
340 for (int i = 0; i < n; i++) {
341 int ind = index + i;
342 assert(ind < _capacity, "By overflow test above.");
343 _base[ind] = ptr_arr[i];
344 }
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_push_arr(oop* ptr_arr, int n) {
353 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
354 jint start = _index;
355 jint next_index = start + n;
356 if (next_index > _capacity) {
357 _overflow = true;
358 return;
359 }
360 // Otherwise.
361 _index = next_index;
362 for (int i = 0; i < n; i++) {
363 int ind = start + i;
364 assert(ind < _capacity, "By overflow test above.");
365 _base[ind] = ptr_arr[i];
366 }
367 NOT_PRODUCT(_max_depth = MAX2(_max_depth, next_index));
368 }
369
370 bool CMMarkStack::par_pop_arr(oop* ptr_arr, int max, int* n) {
371 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
372 jint index = _index;
373 if (index == 0) {
374 *n = 0;
375 return false;
376 } else {
377 int k = MIN2(max, index);
378 jint new_ind = index - k;
379 for (int j = 0; j < k; j++) {
380 ptr_arr[j] = _base[new_ind + j];
381 }
382 _index = new_ind;
383 *n = k;
384 return true;
385 }
386 }
387
388 template<class OopClosureClass>
389 bool CMMarkStack::drain(OopClosureClass* cl, CMBitMap* bm, bool yield_after) {
390 assert(!_drain_in_progress || !_drain_in_progress_yields || yield_after
391 || SafepointSynchronize::is_at_safepoint(),
392 "Drain recursion must be yield-safe.");
393 bool res = true;
394 debug_only(_drain_in_progress = true);
395 debug_only(_drain_in_progress_yields = yield_after);
396 while (!isEmpty()) {
397 oop newOop = pop();
398 assert(G1CollectedHeap::heap()->is_in_reserved(newOop), "Bad pop");
399 assert(newOop->is_oop(), "Expected an oop");
400 assert(bm == NULL || bm->isMarked((HeapWord*)newOop),
401 "only grey objects on this stack");
402 newOop->oop_iterate(cl);
403 if (yield_after && _cm->do_yield_check()) {
404 res = false;
405 break;
406 }
407 }
408 debug_only(_drain_in_progress = false);
409 return res;
410 }
411
412 void CMMarkStack::note_start_of_gc() {
413 assert(_saved_index == -1,
414 "note_start_of_gc()/end_of_gc() bracketed incorrectly");
415 _saved_index = _index;
416 }
417
418 void CMMarkStack::note_end_of_gc() {
419 // This is intentionally a guarantee, instead of an assert. If we
420 // accidentally add something to the mark stack during GC, it
421 // will be a correctness issue so it's better if we crash. we'll
422 // only check this once per GC anyway, so it won't be a performance
423 // issue in any way.
424 guarantee(_saved_index == _index,
425 err_msg("saved index: %d index: %d", _saved_index, _index));
426 _saved_index = -1;
427 }
428
429 void CMMarkStack::oops_do(OopClosure* f) {
430 assert(_saved_index == _index,
431 err_msg("saved index: %d index: %d", _saved_index, _index));
432 for (int i = 0; i < _index; i += 1) {
433 f->do_oop(&_base[i]);
434 }
435 }
436
437 CMRootRegions::CMRootRegions() :
438 _young_list(NULL), _cm(NULL), _scan_in_progress(false),
439 _should_abort(false), _next_survivor(NULL) { }
440
441 void CMRootRegions::init(G1CollectedHeap* g1h, ConcurrentMark* cm) {
442 _young_list = g1h->young_list();
443 _cm = cm;
444 }
445
446 void CMRootRegions::prepare_for_scan() {
447 assert(!scan_in_progress(), "pre-condition");
448
449 // Currently, only survivors can be root regions.
450 assert(_next_survivor == NULL, "pre-condition");
451 _next_survivor = _young_list->first_survivor_region();
452 _scan_in_progress = (_next_survivor != NULL);
453 _should_abort = false;
454 }
455
456 HeapRegion* CMRootRegions::claim_next() {
457 if (_should_abort) {
458 // If someone has set the should_abort flag, we return NULL to
459 // force the caller to bail out of their loop.
460 return NULL;
461 }
462
463 // Currently, only survivors can be root regions.
464 HeapRegion* res = _next_survivor;
465 if (res != NULL) {
466 MutexLockerEx x(RootRegionScan_lock, Mutex::_no_safepoint_check_flag);
467 // Read it again in case it changed while we were waiting for the lock.
468 res = _next_survivor;
469 if (res != NULL) {
470 if (res == _young_list->last_survivor_region()) {
471 // We just claimed the last survivor so store NULL to indicate
472 // that we're done.
473 _next_survivor = NULL;
474 } else {
475 _next_survivor = res->get_next_young_region();
476 }
477 } else {
478 // Someone else claimed the last survivor while we were trying
479 // to take the lock so nothing else to do.
480 }
481 }
482 assert(res == NULL || res->is_survivor(), "post-condition");
483
484 return res;
485 }
486
487 void CMRootRegions::scan_finished() {
488 assert(scan_in_progress(), "pre-condition");
489
490 // Currently, only survivors can be root regions.
491 if (!_should_abort) {
492 assert(_next_survivor == NULL, "we should have claimed all survivors");
493 }
494 _next_survivor = NULL;
495
496 {
497 MutexLockerEx x(RootRegionScan_lock, Mutex::_no_safepoint_check_flag);
498 _scan_in_progress = false;
499 RootRegionScan_lock->notify_all();
500 }
501 }
502
503 bool CMRootRegions::wait_until_scan_finished() {
504 if (!scan_in_progress()) return false;
505
506 {
507 MutexLockerEx x(RootRegionScan_lock, Mutex::_no_safepoint_check_flag);
508 while (scan_in_progress()) {
509 RootRegionScan_lock->wait(Mutex::_no_safepoint_check_flag);
510 }
511 }
512 return true;
513 }
514
515 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
516 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
517 #endif // _MSC_VER
518
519 uint ConcurrentMark::scale_parallel_threads(uint n_par_threads) {
520 return MAX2((n_par_threads + 2) / 4, 1U);
521 }
522
523 ConcurrentMark::ConcurrentMark(G1CollectedHeap* g1h, G1RegionToSpaceMapper* prev_bitmap_storage, G1RegionToSpaceMapper* next_bitmap_storage) :
524 _g1h(g1h),
525 _markBitMap1(),
526 _markBitMap2(),
527 _parallel_marking_threads(0),
528 _max_parallel_marking_threads(0),
529 _sleep_factor(0.0),
530 _marking_task_overhead(1.0),
531 _cleanup_sleep_factor(0.0),
532 _cleanup_task_overhead(1.0),
533 _cleanup_list("Cleanup List"),
534 _region_bm((BitMap::idx_t)(g1h->max_regions()), false /* in_resource_area*/),
535 _card_bm((g1h->reserved_region().byte_size() + CardTableModRefBS::card_size - 1) >>
536 CardTableModRefBS::card_shift,
537 false /* in_resource_area*/),
538
539 _prevMarkBitMap(&_markBitMap1),
540 _nextMarkBitMap(&_markBitMap2),
541
542 _markStack(this),
543 // _finger set in set_non_marking_state
544
545 _max_worker_id(MAX2((uint)ParallelGCThreads, 1U)),
546 // _active_tasks set in set_non_marking_state
547 // _tasks set inside the constructor
548 _task_queues(new CMTaskQueueSet((int) _max_worker_id)),
549 _terminator(ParallelTaskTerminator((int) _max_worker_id, _task_queues)),
550
551 _has_overflown(false),
552 _concurrent(false),
553 _has_aborted(false),
554 _aborted_gc_id(GCId::undefined()),
555 _restart_for_overflow(false),
556 _concurrent_marking_in_progress(false),
557
558 // _verbose_level set below
559
560 _init_times(),
561 _remark_times(), _remark_mark_times(), _remark_weak_ref_times(),
562 _cleanup_times(),
563 _total_counting_time(0.0),
564 _total_rs_scrub_time(0.0),
565
566 _parallel_workers(NULL),
567
568 _count_card_bitmaps(NULL),
569 _count_marked_bytes(NULL),
570 _completed_initialization(false) {
571 CMVerboseLevel verbose_level = (CMVerboseLevel) G1MarkingVerboseLevel;
572 if (verbose_level < no_verbose) {
573 verbose_level = no_verbose;
574 }
575 if (verbose_level > high_verbose) {
576 verbose_level = high_verbose;
577 }
578 _verbose_level = verbose_level;
579
580 if (verbose_low()) {
581 gclog_or_tty->print_cr("[global] init, heap start = "PTR_FORMAT", "
582 "heap end = " PTR_FORMAT, p2i(_heap_start), p2i(_heap_end));
583 }
584
585 _markBitMap1.initialize(g1h->reserved_region(), prev_bitmap_storage);
586 _markBitMap2.initialize(g1h->reserved_region(), next_bitmap_storage);
587
588 // Create & start a ConcurrentMark thread.
589 _cmThread = new ConcurrentMarkThread(this);
590 assert(cmThread() != NULL, "CM Thread should have been created");
591 assert(cmThread()->cm() != NULL, "CM Thread should refer to this cm");
592 if (_cmThread->osthread() == NULL) {
593 vm_shutdown_during_initialization("Could not create ConcurrentMarkThread");
594 }
595
596 assert(CGC_lock != NULL, "Where's the CGC_lock?");
597 assert(_markBitMap1.covers(g1h->reserved_region()), "_markBitMap1 inconsistency");
598 assert(_markBitMap2.covers(g1h->reserved_region()), "_markBitMap2 inconsistency");
599
600 SATBMarkQueueSet& satb_qs = JavaThread::satb_mark_queue_set();
601 satb_qs.set_buffer_size(G1SATBBufferSize);
602
603 _root_regions.init(_g1h, this);
604
605 if (ConcGCThreads > ParallelGCThreads) {
606 warning("Can't have more ConcGCThreads (" UINTX_FORMAT ") "
607 "than ParallelGCThreads (" UINTX_FORMAT ").",
608 ConcGCThreads, ParallelGCThreads);
609 return;
610 }
611 if (ParallelGCThreads == 0) {
612 // if we are not running with any parallel GC threads we will not
613 // spawn any marking threads either
614 _parallel_marking_threads = 0;
615 _max_parallel_marking_threads = 0;
616 _sleep_factor = 0.0;
617 _marking_task_overhead = 1.0;
618 } else {
619 if (!FLAG_IS_DEFAULT(ConcGCThreads) && ConcGCThreads > 0) {
620 // Note: ConcGCThreads has precedence over G1MarkingOverheadPercent
621 // if both are set
622 _sleep_factor = 0.0;
623 _marking_task_overhead = 1.0;
624 } else if (G1MarkingOverheadPercent > 0) {
625 // We will calculate the number of parallel marking threads based
626 // on a target overhead with respect to the soft real-time goal
627 double marking_overhead = (double) G1MarkingOverheadPercent / 100.0;
628 double overall_cm_overhead =
629 (double) MaxGCPauseMillis * marking_overhead /
630 (double) GCPauseIntervalMillis;
631 double cpu_ratio = 1.0 / (double) os::processor_count();
632 double marking_thread_num = ceil(overall_cm_overhead / cpu_ratio);
633 double marking_task_overhead =
634 overall_cm_overhead / marking_thread_num *
635 (double) os::processor_count();
636 double sleep_factor =
637 (1.0 - marking_task_overhead) / marking_task_overhead;
638
639 FLAG_SET_ERGO(uintx, ConcGCThreads, (uint) marking_thread_num);
640 _sleep_factor = sleep_factor;
641 _marking_task_overhead = marking_task_overhead;
642 } else {
643 // Calculate the number of parallel marking threads by scaling
644 // the number of parallel GC threads.
645 uint marking_thread_num = scale_parallel_threads((uint) ParallelGCThreads);
646 FLAG_SET_ERGO(uintx, ConcGCThreads, marking_thread_num);
647 _sleep_factor = 0.0;
648 _marking_task_overhead = 1.0;
649 }
650
651 assert(ConcGCThreads > 0, "Should have been set");
652 _parallel_marking_threads = (uint) ConcGCThreads;
653 _max_parallel_marking_threads = _parallel_marking_threads;
654
655 if (parallel_marking_threads() > 1) {
656 _cleanup_task_overhead = 1.0;
657 } else {
658 _cleanup_task_overhead = marking_task_overhead();
659 }
660 _cleanup_sleep_factor =
661 (1.0 - cleanup_task_overhead()) / cleanup_task_overhead();
662
663 #if 0
664 gclog_or_tty->print_cr("Marking Threads %d", parallel_marking_threads());
665 gclog_or_tty->print_cr("CM Marking Task Overhead %1.4lf", marking_task_overhead());
666 gclog_or_tty->print_cr("CM Sleep Factor %1.4lf", sleep_factor());
667 gclog_or_tty->print_cr("CL Marking Task Overhead %1.4lf", cleanup_task_overhead());
668 gclog_or_tty->print_cr("CL Sleep Factor %1.4lf", cleanup_sleep_factor());
669 #endif
670
671 guarantee(parallel_marking_threads() > 0, "peace of mind");
672 _parallel_workers = new FlexibleWorkGang("G1 Parallel Marking Threads",
673 _max_parallel_marking_threads, false, true);
674 if (_parallel_workers == NULL) {
675 vm_exit_during_initialization("Failed necessary allocation.");
676 } else {
677 _parallel_workers->initialize_workers();
678 }
679 }
680
681 if (FLAG_IS_DEFAULT(MarkStackSize)) {
682 uintx mark_stack_size =
683 MIN2(MarkStackSizeMax,
684 MAX2(MarkStackSize, (uintx) (parallel_marking_threads() * TASKQUEUE_SIZE)));
685 // Verify that the calculated value for MarkStackSize is in range.
686 // It would be nice to use the private utility routine from Arguments.
687 if (!(mark_stack_size >= 1 && mark_stack_size <= MarkStackSizeMax)) {
688 warning("Invalid value calculated for MarkStackSize (" UINTX_FORMAT "): "
689 "must be between " UINTX_FORMAT " and " UINTX_FORMAT,
690 mark_stack_size, (uintx) 1, MarkStackSizeMax);
691 return;
692 }
693 FLAG_SET_ERGO(uintx, MarkStackSize, mark_stack_size);
694 } else {
695 // Verify MarkStackSize is in range.
696 if (FLAG_IS_CMDLINE(MarkStackSize)) {
697 if (FLAG_IS_DEFAULT(MarkStackSizeMax)) {
698 if (!(MarkStackSize >= 1 && MarkStackSize <= MarkStackSizeMax)) {
699 warning("Invalid value specified for MarkStackSize (" UINTX_FORMAT "): "
700 "must be between " UINTX_FORMAT " and " UINTX_FORMAT,
701 MarkStackSize, (uintx) 1, MarkStackSizeMax);
702 return;
703 }
704 } else if (FLAG_IS_CMDLINE(MarkStackSizeMax)) {
705 if (!(MarkStackSize >= 1 && MarkStackSize <= MarkStackSizeMax)) {
706 warning("Invalid value specified for MarkStackSize (" UINTX_FORMAT ")"
707 " or for MarkStackSizeMax (" UINTX_FORMAT ")",
708 MarkStackSize, MarkStackSizeMax);
709 return;
710 }
711 }
712 }
713 }
714
715 if (!_markStack.allocate(MarkStackSize)) {
716 warning("Failed to allocate CM marking stack");
717 return;
718 }
719
720 _tasks = NEW_C_HEAP_ARRAY(CMTask*, _max_worker_id, mtGC);
721 _accum_task_vtime = NEW_C_HEAP_ARRAY(double, _max_worker_id, mtGC);
722
723 _count_card_bitmaps = NEW_C_HEAP_ARRAY(BitMap, _max_worker_id, mtGC);
724 _count_marked_bytes = NEW_C_HEAP_ARRAY(size_t*, _max_worker_id, mtGC);
725
726 BitMap::idx_t card_bm_size = _card_bm.size();
727
728 // so that the assertion in MarkingTaskQueue::task_queue doesn't fail
729 _active_tasks = _max_worker_id;
730
731 size_t max_regions = (size_t) _g1h->max_regions();
732 for (uint i = 0; i < _max_worker_id; ++i) {
733 CMTaskQueue* task_queue = new CMTaskQueue();
734 task_queue->initialize();
735 _task_queues->register_queue(i, task_queue);
736
737 _count_card_bitmaps[i] = BitMap(card_bm_size, false);
738 _count_marked_bytes[i] = NEW_C_HEAP_ARRAY(size_t, max_regions, mtGC);
739
740 _tasks[i] = new CMTask(i, this,
741 _count_marked_bytes[i],
742 &_count_card_bitmaps[i],
743 task_queue, _task_queues);
744
745 _accum_task_vtime[i] = 0.0;
746 }
747
748 // Calculate the card number for the bottom of the heap. Used
749 // in biasing indexes into the accounting card bitmaps.
750 _heap_bottom_card_num =
751 intptr_t(uintptr_t(_g1h->reserved_region().start()) >>
752 CardTableModRefBS::card_shift);
753
754 // Clear all the liveness counting data
755 clear_all_count_data();
756
757 // so that the call below can read a sensible value
758 _heap_start = g1h->reserved_region().start();
759 set_non_marking_state();
760 _completed_initialization = true;
761 }
762
763 void ConcurrentMark::reset() {
764 // Starting values for these two. This should be called in a STW
765 // phase.
766 MemRegion reserved = _g1h->g1_reserved();
767 _heap_start = reserved.start();
768 _heap_end = reserved.end();
769
770 // Separated the asserts so that we know which one fires.
771 assert(_heap_start != NULL, "heap bounds should look ok");
772 assert(_heap_end != NULL, "heap bounds should look ok");
773 assert(_heap_start < _heap_end, "heap bounds should look ok");
774
775 // Reset all the marking data structures and any necessary flags
776 reset_marking_state();
777
778 if (verbose_low()) {
779 gclog_or_tty->print_cr("[global] resetting");
780 }
781
782 // We do reset all of them, since different phases will use
783 // different number of active threads. So, it's easiest to have all
784 // of them ready.
785 for (uint i = 0; i < _max_worker_id; ++i) {
786 _tasks[i]->reset(_nextMarkBitMap);
787 }
788
789 // we need this to make sure that the flag is on during the evac
790 // pause with initial mark piggy-backed
791 set_concurrent_marking_in_progress();
792 }
793
794
795 void ConcurrentMark::reset_marking_state(bool clear_overflow) {
796 _markStack.set_should_expand();
797 _markStack.setEmpty(); // Also clears the _markStack overflow flag
798 if (clear_overflow) {
799 clear_has_overflown();
800 } else {
801 assert(has_overflown(), "pre-condition");
802 }
803 _finger = _heap_start;
804
805 for (uint i = 0; i < _max_worker_id; ++i) {
806 CMTaskQueue* queue = _task_queues->queue(i);
807 queue->set_empty();
808 }
809 }
810
811 void ConcurrentMark::set_concurrency(uint active_tasks) {
812 assert(active_tasks <= _max_worker_id, "we should not have more");
813
814 _active_tasks = active_tasks;
815 // Need to update the three data structures below according to the
816 // number of active threads for this phase.
817 _terminator = ParallelTaskTerminator((int) active_tasks, _task_queues);
818 _first_overflow_barrier_sync.set_n_workers((int) active_tasks);
819 _second_overflow_barrier_sync.set_n_workers((int) active_tasks);
820 }
821
822 void ConcurrentMark::set_concurrency_and_phase(uint active_tasks, bool concurrent) {
823 set_concurrency(active_tasks);
824
825 _concurrent = concurrent;
826 // We propagate this to all tasks, not just the active ones.
827 for (uint i = 0; i < _max_worker_id; ++i)
828 _tasks[i]->set_concurrent(concurrent);
829
830 if (concurrent) {
831 set_concurrent_marking_in_progress();
832 } else {
833 // We currently assume that the concurrent flag has been set to
834 // false before we start remark. At this point we should also be
835 // in a STW phase.
836 assert(!concurrent_marking_in_progress(), "invariant");
837 assert(out_of_regions(),
838 err_msg("only way to get here: _finger: "PTR_FORMAT", _heap_end: "PTR_FORMAT,
839 p2i(_finger), p2i(_heap_end)));
840 }
841 }
842
843 void ConcurrentMark::set_non_marking_state() {
844 // We set the global marking state to some default values when we're
845 // not doing marking.
846 reset_marking_state();
847 _active_tasks = 0;
848 clear_concurrent_marking_in_progress();
849 }
850
851 ConcurrentMark::~ConcurrentMark() {
852 // The ConcurrentMark instance is never freed.
853 ShouldNotReachHere();
854 }
855
856 void ConcurrentMark::clearNextBitmap() {
857 G1CollectedHeap* g1h = G1CollectedHeap::heap();
858
859 // Make sure that the concurrent mark thread looks to still be in
860 // the current cycle.
861 guarantee(cmThread()->during_cycle(), "invariant");
862
863 // We are finishing up the current cycle by clearing the next
864 // marking bitmap and getting it ready for the next cycle. During
865 // this time no other cycle can start. So, let's make sure that this
866 // is the case.
867 guarantee(!g1h->mark_in_progress(), "invariant");
868
869 ClearBitmapHRClosure cl(this, _nextMarkBitMap, true /* may_yield */);
870 g1h->heap_region_iterate(&cl);
871
872 // Clear the liveness counting data. If the marking has been aborted, the abort()
873 // call already did that.
874 if (cl.complete()) {
875 clear_all_count_data();
876 }
877
878 // Repeat the asserts from above.
879 guarantee(cmThread()->during_cycle(), "invariant");
880 guarantee(!g1h->mark_in_progress(), "invariant");
881 }
882
883 class CheckBitmapClearHRClosure : public HeapRegionClosure {
884 CMBitMap* _bitmap;
885 bool _error;
886 public:
887 CheckBitmapClearHRClosure(CMBitMap* bitmap) : _bitmap(bitmap) {
888 }
889
890 virtual bool doHeapRegion(HeapRegion* r) {
891 return _bitmap->getNextMarkedWordAddress(r->bottom(), r->end()) != r->end();
892 }
893 };
894
895 bool ConcurrentMark::nextMarkBitmapIsClear() {
896 CheckBitmapClearHRClosure cl(_nextMarkBitMap);
897 _g1h->heap_region_iterate(&cl);
898 return cl.complete();
899 }
900
901 class NoteStartOfMarkHRClosure: public HeapRegionClosure {
902 public:
903 bool doHeapRegion(HeapRegion* r) {
904 if (!r->continuesHumongous()) {
905 r->note_start_of_marking();
906 }
907 return false;
908 }
909 };
910
911 void ConcurrentMark::checkpointRootsInitialPre() {
912 G1CollectedHeap* g1h = G1CollectedHeap::heap();
913 G1CollectorPolicy* g1p = g1h->g1_policy();
914
915 _has_aborted = false;
916
917 #ifndef PRODUCT
918 if (G1PrintReachableAtInitialMark) {
919 print_reachable("at-cycle-start",
920 VerifyOption_G1UsePrevMarking, true /* all */);
921 }
922 #endif
923
924 // Initialize marking structures. This has to be done in a STW phase.
925 reset();
926
927 // For each region note start of marking.
928 NoteStartOfMarkHRClosure startcl;
929 g1h->heap_region_iterate(&startcl);
930 }
931
932
933 void ConcurrentMark::checkpointRootsInitialPost() {
934 G1CollectedHeap* g1h = G1CollectedHeap::heap();
935
936 // If we force an overflow during remark, the remark operation will
937 // actually abort and we'll restart concurrent marking. If we always
938 // force an overflow during remark we'll never actually complete the
939 // marking phase. So, we initialize this here, at the start of the
940 // cycle, so that at the remaining overflow number will decrease at
941 // every remark and we'll eventually not need to cause one.
942 force_overflow_stw()->init();
943
944 // Start Concurrent Marking weak-reference discovery.
945 ReferenceProcessor* rp = g1h->ref_processor_cm();
946 // enable ("weak") refs discovery
947 rp->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
948 rp->setup_policy(false); // snapshot the soft ref policy to be used in this cycle
949
950 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
951 // This is the start of the marking cycle, we're expected all
952 // threads to have SATB queues with active set to false.
953 satb_mq_set.set_active_all_threads(true, /* new active value */
954 false /* expected_active */);
955
956 _root_regions.prepare_for_scan();
957
958 // update_g1_committed() will be called at the end of an evac pause
959 // when marking is on. So, it's also called at the end of the
960 // initial-mark pause to update the heap end, if the heap expands
961 // during it. No need to call it here.
962 }
963
964 /*
965 * Notice that in the next two methods, we actually leave the STS
966 * during the barrier sync and join it immediately afterwards. If we
967 * do not do this, the following deadlock can occur: one thread could
968 * be in the barrier sync code, waiting for the other thread to also
969 * sync up, whereas another one could be trying to yield, while also
970 * waiting for the other threads to sync up too.
971 *
972 * Note, however, that this code is also used during remark and in
973 * this case we should not attempt to leave / enter the STS, otherwise
974 * we'll either hit an assert (debug / fastdebug) or deadlock
975 * (product). So we should only leave / enter the STS if we are
976 * operating concurrently.
977 *
978 * Because the thread that does the sync barrier has left the STS, it
979 * is possible to be suspended for a Full GC or an evacuation pause
980 * could occur. This is actually safe, since the entering the sync
981 * barrier is one of the last things do_marking_step() does, and it
982 * doesn't manipulate any data structures afterwards.
983 */
984
985 void ConcurrentMark::enter_first_sync_barrier(uint worker_id) {
986 if (verbose_low()) {
987 gclog_or_tty->print_cr("[%u] entering first barrier", worker_id);
988 }
989
990 if (concurrent()) {
991 SuspendibleThreadSet::leave();
992 }
993
994 bool barrier_aborted = !_first_overflow_barrier_sync.enter();
995
996 if (concurrent()) {
997 SuspendibleThreadSet::join();
998 }
999 // at this point everyone should have synced up and not be doing any
1000 // more work
1001
1002 if (verbose_low()) {
1003 if (barrier_aborted) {
1004 gclog_or_tty->print_cr("[%u] aborted first barrier", worker_id);
1005 } else {
1006 gclog_or_tty->print_cr("[%u] leaving first barrier", worker_id);
1007 }
1008 }
1009
1010 if (barrier_aborted) {
1011 // If the barrier aborted we ignore the overflow condition and
1012 // just abort the whole marking phase as quickly as possible.
1013 return;
1014 }
1015
1016 // If we're executing the concurrent phase of marking, reset the marking
1017 // state; otherwise the marking state is reset after reference processing,
1018 // during the remark pause.
1019 // If we reset here as a result of an overflow during the remark we will
1020 // see assertion failures from any subsequent set_concurrency_and_phase()
1021 // calls.
1022 if (concurrent()) {
1023 // let the task associated with with worker 0 do this
1024 if (worker_id == 0) {
1025 // task 0 is responsible for clearing the global data structures
1026 // We should be here because of an overflow. During STW we should
1027 // not clear the overflow flag since we rely on it being true when
1028 // we exit this method to abort the pause and restart concurrent
1029 // marking.
1030 reset_marking_state(true /* clear_overflow */);
1031 force_overflow()->update();
1032
1033 if (G1Log::fine()) {
1034 gclog_or_tty->gclog_stamp(concurrent_gc_id());
1035 gclog_or_tty->print_cr("[GC concurrent-mark-reset-for-overflow]");
1036 }
1037 }
1038 }
1039
1040 // after this, each task should reset its own data structures then
1041 // then go into the second barrier
1042 }
1043
1044 void ConcurrentMark::enter_second_sync_barrier(uint worker_id) {
1045 if (verbose_low()) {
1046 gclog_or_tty->print_cr("[%u] entering second barrier", worker_id);
1047 }
1048
1049 if (concurrent()) {
1050 SuspendibleThreadSet::leave();
1051 }
1052
1053 bool barrier_aborted = !_second_overflow_barrier_sync.enter();
1054
1055 if (concurrent()) {
1056 SuspendibleThreadSet::join();
1057 }
1058 // at this point everything should be re-initialized and ready to go
1059
1060 if (verbose_low()) {
1061 if (barrier_aborted) {
1062 gclog_or_tty->print_cr("[%u] aborted second barrier", worker_id);
1063 } else {
1064 gclog_or_tty->print_cr("[%u] leaving second barrier", worker_id);
1065 }
1066 }
1067 }
1068
1069 #ifndef PRODUCT
1070 void ForceOverflowSettings::init() {
1071 _num_remaining = G1ConcMarkForceOverflow;
1072 _force = false;
1073 update();
1074 }
1075
1076 void ForceOverflowSettings::update() {
1077 if (_num_remaining > 0) {
1078 _num_remaining -= 1;
1079 _force = true;
1080 } else {
1081 _force = false;
1082 }
1083 }
1084
1085 bool ForceOverflowSettings::should_force() {
1086 if (_force) {
1087 _force = false;
1088 return true;
1089 } else {
1090 return false;
1091 }
1092 }
1093 #endif // !PRODUCT
1094
1095 class CMConcurrentMarkingTask: public AbstractGangTask {
1096 private:
1097 ConcurrentMark* _cm;
1098 ConcurrentMarkThread* _cmt;
1099
1100 public:
1101 void work(uint worker_id) {
1102 assert(Thread::current()->is_ConcurrentGC_thread(),
1103 "this should only be done by a conc GC thread");
1104 ResourceMark rm;
1105
1106 double start_vtime = os::elapsedVTime();
1107
1108 SuspendibleThreadSet::join();
1109
1110 assert(worker_id < _cm->active_tasks(), "invariant");
1111 CMTask* the_task = _cm->task(worker_id);
1112 the_task->record_start_time();
1113 if (!_cm->has_aborted()) {
1114 do {
1115 double start_vtime_sec = os::elapsedVTime();
1116 double mark_step_duration_ms = G1ConcMarkStepDurationMillis;
1117
1118 the_task->do_marking_step(mark_step_duration_ms,
1119 true /* do_termination */,
1120 false /* is_serial*/);
1121
1122 double end_vtime_sec = os::elapsedVTime();
1123 double elapsed_vtime_sec = end_vtime_sec - start_vtime_sec;
1124 _cm->clear_has_overflown();
1125
1126 _cm->do_yield_check(worker_id);
1127
1128 jlong sleep_time_ms;
1129 if (!_cm->has_aborted() && the_task->has_aborted()) {
1130 sleep_time_ms =
1131 (jlong) (elapsed_vtime_sec * _cm->sleep_factor() * 1000.0);
1132 SuspendibleThreadSet::leave();
1133 os::sleep(Thread::current(), sleep_time_ms, false);
1134 SuspendibleThreadSet::join();
1135 }
1136 } while (!_cm->has_aborted() && the_task->has_aborted());
1137 }
1138 the_task->record_end_time();
1139 guarantee(!the_task->has_aborted() || _cm->has_aborted(), "invariant");
1140
1141 SuspendibleThreadSet::leave();
1142
1143 double end_vtime = os::elapsedVTime();
1144 _cm->update_accum_task_vtime(worker_id, end_vtime - start_vtime);
1145 }
1146
1147 CMConcurrentMarkingTask(ConcurrentMark* cm,
1148 ConcurrentMarkThread* cmt) :
1149 AbstractGangTask("Concurrent Mark"), _cm(cm), _cmt(cmt) { }
1150
1151 ~CMConcurrentMarkingTask() { }
1152 };
1153
1154 // Calculates the number of active workers for a concurrent
1155 // phase.
1156 uint ConcurrentMark::calc_parallel_marking_threads() {
1157 if (G1CollectedHeap::use_parallel_gc_threads()) {
1158 uint n_conc_workers = 0;
1159 if (!UseDynamicNumberOfGCThreads ||
1160 (!FLAG_IS_DEFAULT(ConcGCThreads) &&
1161 !ForceDynamicNumberOfGCThreads)) {
1162 n_conc_workers = max_parallel_marking_threads();
1163 } else {
1164 n_conc_workers =
1165 AdaptiveSizePolicy::calc_default_active_workers(
1166 max_parallel_marking_threads(),
1167 1, /* Minimum workers */
1168 parallel_marking_threads(),
1169 Threads::number_of_non_daemon_threads());
1170 // Don't scale down "n_conc_workers" by scale_parallel_threads() because
1171 // that scaling has already gone into "_max_parallel_marking_threads".
1172 }
1173 assert(n_conc_workers > 0, "Always need at least 1");
1174 return n_conc_workers;
1175 }
1176 // If we are not running with any parallel GC threads we will not
1177 // have spawned any marking threads either. Hence the number of
1178 // concurrent workers should be 0.
1179 return 0;
1180 }
1181
1182 void ConcurrentMark::scanRootRegion(HeapRegion* hr, uint worker_id) {
1183 // Currently, only survivors can be root regions.
1184 assert(hr->next_top_at_mark_start() == hr->bottom(), "invariant");
1185 G1RootRegionScanClosure cl(_g1h, this, worker_id);
1186
1187 const uintx interval = PrefetchScanIntervalInBytes;
1188 HeapWord* curr = hr->bottom();
1189 const HeapWord* end = hr->top();
1190 while (curr < end) {
1191 Prefetch::read(curr, interval);
1192 oop obj = oop(curr);
1193 int size = obj->oop_iterate(&cl);
1194 assert(size == obj->size(), "sanity");
1195 curr += size;
1196 }
1197 }
1198
1199 class CMRootRegionScanTask : public AbstractGangTask {
1200 private:
1201 ConcurrentMark* _cm;
1202
1203 public:
1204 CMRootRegionScanTask(ConcurrentMark* cm) :
1205 AbstractGangTask("Root Region Scan"), _cm(cm) { }
1206
1207 void work(uint worker_id) {
1208 assert(Thread::current()->is_ConcurrentGC_thread(),
1209 "this should only be done by a conc GC thread");
1210
1211 CMRootRegions* root_regions = _cm->root_regions();
1212 HeapRegion* hr = root_regions->claim_next();
1213 while (hr != NULL) {
1214 _cm->scanRootRegion(hr, worker_id);
1215 hr = root_regions->claim_next();
1216 }
1217 }
1218 };
1219
1220 void ConcurrentMark::scanRootRegions() {
1221 // Start of concurrent marking.
1222 ClassLoaderDataGraph::clear_claimed_marks();
1223
1224 // scan_in_progress() will have been set to true only if there was
1225 // at least one root region to scan. So, if it's false, we
1226 // should not attempt to do any further work.
1227 if (root_regions()->scan_in_progress()) {
1228 _parallel_marking_threads = calc_parallel_marking_threads();
1229 assert(parallel_marking_threads() <= max_parallel_marking_threads(),
1230 "Maximum number of marking threads exceeded");
1231 uint active_workers = MAX2(1U, parallel_marking_threads());
1232
1233 CMRootRegionScanTask task(this);
1234 if (use_parallel_marking_threads()) {
1235 _parallel_workers->set_active_workers((int) active_workers);
1236 _parallel_workers->run_task(&task);
1237 } else {
1238 task.work(0);
1239 }
1240
1241 // It's possible that has_aborted() is true here without actually
1242 // aborting the survivor scan earlier. This is OK as it's
1243 // mainly used for sanity checking.
1244 root_regions()->scan_finished();
1245 }
1246 }
1247
1248 void ConcurrentMark::markFromRoots() {
1249 // we might be tempted to assert that:
1250 // assert(asynch == !SafepointSynchronize::is_at_safepoint(),
1251 // "inconsistent argument?");
1252 // However that wouldn't be right, because it's possible that
1253 // a safepoint is indeed in progress as a younger generation
1254 // stop-the-world GC happens even as we mark in this generation.
1255
1256 _restart_for_overflow = false;
1257 force_overflow_conc()->init();
1258
1259 // _g1h has _n_par_threads
1260 _parallel_marking_threads = calc_parallel_marking_threads();
1261 assert(parallel_marking_threads() <= max_parallel_marking_threads(),
1262 "Maximum number of marking threads exceeded");
1263
1264 uint active_workers = MAX2(1U, parallel_marking_threads());
1265
1266 // Parallel task terminator is set in "set_concurrency_and_phase()"
1267 set_concurrency_and_phase(active_workers, true /* concurrent */);
1268
1269 CMConcurrentMarkingTask markingTask(this, cmThread());
1270 if (use_parallel_marking_threads()) {
1271 _parallel_workers->set_active_workers((int)active_workers);
1272 // Don't set _n_par_threads because it affects MT in process_roots()
1273 // and the decisions on that MT processing is made elsewhere.
1274 assert(_parallel_workers->active_workers() > 0, "Should have been set");
1275 _parallel_workers->run_task(&markingTask);
1276 } else {
1277 markingTask.work(0);
1278 }
1279 print_stats();
1280 }
1281
1282 void ConcurrentMark::checkpointRootsFinal(bool clear_all_soft_refs) {
1283 // world is stopped at this checkpoint
1284 assert(SafepointSynchronize::is_at_safepoint(),
1285 "world should be stopped");
1286
1287 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1288
1289 // If a full collection has happened, we shouldn't do this.
1290 if (has_aborted()) {
1291 g1h->set_marking_complete(); // So bitmap clearing isn't confused
1292 return;
1293 }
1294
1295 SvcGCMarker sgcm(SvcGCMarker::OTHER);
1296
1297 if (VerifyDuringGC) {
1298 HandleMark hm; // handle scope
1299 Universe::heap()->prepare_for_verify();
1300 Universe::verify(VerifyOption_G1UsePrevMarking,
1301 " VerifyDuringGC:(before)");
1302 }
1303 g1h->check_bitmaps("Remark Start");
1304
1305 G1CollectorPolicy* g1p = g1h->g1_policy();
1306 g1p->record_concurrent_mark_remark_start();
1307
1308 double start = os::elapsedTime();
1309
1310 checkpointRootsFinalWork();
1311
1312 double mark_work_end = os::elapsedTime();
1313
1314 weakRefsWork(clear_all_soft_refs);
1315
1316 if (has_overflown()) {
1317 // Oops. We overflowed. Restart concurrent marking.
1318 _restart_for_overflow = true;
1319 if (G1TraceMarkStackOverflow) {
1320 gclog_or_tty->print_cr("\nRemark led to restart for overflow.");
1321 }
1322
1323 // Verify the heap w.r.t. the previous marking bitmap.
1324 if (VerifyDuringGC) {
1325 HandleMark hm; // handle scope
1326 Universe::heap()->prepare_for_verify();
1327 Universe::verify(VerifyOption_G1UsePrevMarking,
1328 " VerifyDuringGC:(overflow)");
1329 }
1330
1331 // Clear the marking state because we will be restarting
1332 // marking due to overflowing the global mark stack.
1333 reset_marking_state();
1334 } else {
1335 // Aggregate the per-task counting data that we have accumulated
1336 // while marking.
1337 aggregate_count_data();
1338
1339 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
1340 // We're done with marking.
1341 // This is the end of the marking cycle, we're expected all
1342 // threads to have SATB queues with active set to true.
1343 satb_mq_set.set_active_all_threads(false, /* new active value */
1344 true /* expected_active */);
1345
1346 if (VerifyDuringGC) {
1347 HandleMark hm; // handle scope
1348 Universe::heap()->prepare_for_verify();
1349 Universe::verify(VerifyOption_G1UseNextMarking,
1350 " VerifyDuringGC:(after)");
1351 }
1352 g1h->check_bitmaps("Remark End");
1353 assert(!restart_for_overflow(), "sanity");
1354 // Completely reset the marking state since marking completed
1355 set_non_marking_state();
1356 }
1357
1358 // Expand the marking stack, if we have to and if we can.
1359 if (_markStack.should_expand()) {
1360 _markStack.expand();
1361 }
1362
1363 // Statistics
1364 double now = os::elapsedTime();
1365 _remark_mark_times.add((mark_work_end - start) * 1000.0);
1366 _remark_weak_ref_times.add((now - mark_work_end) * 1000.0);
1367 _remark_times.add((now - start) * 1000.0);
1368
1369 g1p->record_concurrent_mark_remark_end();
1370
1371 G1CMIsAliveClosure is_alive(g1h);
1372 g1h->gc_tracer_cm()->report_object_count_after_gc(&is_alive);
1373 }
1374
1375 // Base class of the closures that finalize and verify the
1376 // liveness counting data.
1377 class CMCountDataClosureBase: public HeapRegionClosure {
1378 protected:
1379 G1CollectedHeap* _g1h;
1380 ConcurrentMark* _cm;
1381 CardTableModRefBS* _ct_bs;
1382
1383 BitMap* _region_bm;
1384 BitMap* _card_bm;
1385
1386 // Takes a region that's not empty (i.e., it has at least one
1387 // live object in it and sets its corresponding bit on the region
1388 // bitmap to 1. If the region is "starts humongous" it will also set
1389 // to 1 the bits on the region bitmap that correspond to its
1390 // associated "continues humongous" regions.
1391 void set_bit_for_region(HeapRegion* hr) {
1392 assert(!hr->continuesHumongous(), "should have filtered those out");
1393
1394 BitMap::idx_t index = (BitMap::idx_t) hr->hrm_index();
1395 if (!hr->startsHumongous()) {
1396 // Normal (non-humongous) case: just set the bit.
1397 _region_bm->par_at_put(index, true);
1398 } else {
1399 // Starts humongous case: calculate how many regions are part of
1400 // this humongous region and then set the bit range.
1401 BitMap::idx_t end_index = (BitMap::idx_t) hr->last_hc_index();
1402 _region_bm->par_at_put_range(index, end_index, true);
1403 }
1404 }
1405
1406 public:
1407 CMCountDataClosureBase(G1CollectedHeap* g1h,
1408 BitMap* region_bm, BitMap* card_bm):
1409 _g1h(g1h), _cm(g1h->concurrent_mark()),
1410 _ct_bs((CardTableModRefBS*) (g1h->barrier_set())),
1411 _region_bm(region_bm), _card_bm(card_bm) { }
1412 };
1413
1414 // Closure that calculates the # live objects per region. Used
1415 // for verification purposes during the cleanup pause.
1416 class CalcLiveObjectsClosure: public CMCountDataClosureBase {
1417 CMBitMapRO* _bm;
1418 size_t _region_marked_bytes;
1419
1420 public:
1421 CalcLiveObjectsClosure(CMBitMapRO *bm, G1CollectedHeap* g1h,
1422 BitMap* region_bm, BitMap* card_bm) :
1423 CMCountDataClosureBase(g1h, region_bm, card_bm),
1424 _bm(bm), _region_marked_bytes(0) { }
1425
1426 bool doHeapRegion(HeapRegion* hr) {
1427
1428 if (hr->continuesHumongous()) {
1429 // We will ignore these here and process them when their
1430 // associated "starts humongous" region is processed (see
1431 // set_bit_for_heap_region()). Note that we cannot rely on their
1432 // associated "starts humongous" region to have their bit set to
1433 // 1 since, due to the region chunking in the parallel region
1434 // iteration, a "continues humongous" region might be visited
1435 // before its associated "starts humongous".
1436 return false;
1437 }
1438
1439 HeapWord* ntams = hr->next_top_at_mark_start();
1440 HeapWord* start = hr->bottom();
1441
1442 assert(start <= hr->end() && start <= ntams && ntams <= hr->end(),
1443 err_msg("Preconditions not met - "
1444 "start: "PTR_FORMAT", ntams: "PTR_FORMAT", end: "PTR_FORMAT,
1445 p2i(start), p2i(ntams), p2i(hr->end())));
1446
1447 // Find the first marked object at or after "start".
1448 start = _bm->getNextMarkedWordAddress(start, ntams);
1449
1450 size_t marked_bytes = 0;
1451
1452 while (start < ntams) {
1453 oop obj = oop(start);
1454 int obj_sz = obj->size();
1455 HeapWord* obj_end = start + obj_sz;
1456
1457 BitMap::idx_t start_idx = _cm->card_bitmap_index_for(start);
1458 BitMap::idx_t end_idx = _cm->card_bitmap_index_for(obj_end);
1459
1460 // Note: if we're looking at the last region in heap - obj_end
1461 // could be actually just beyond the end of the heap; end_idx
1462 // will then correspond to a (non-existent) card that is also
1463 // just beyond the heap.
1464 if (_g1h->is_in_g1_reserved(obj_end) && !_ct_bs->is_card_aligned(obj_end)) {
1465 // end of object is not card aligned - increment to cover
1466 // all the cards spanned by the object
1467 end_idx += 1;
1468 }
1469
1470 // Set the bits in the card BM for the cards spanned by this object.
1471 _cm->set_card_bitmap_range(_card_bm, start_idx, end_idx, true /* is_par */);
1472
1473 // Add the size of this object to the number of marked bytes.
1474 marked_bytes += (size_t)obj_sz * HeapWordSize;
1475
1476 // Find the next marked object after this one.
1477 start = _bm->getNextMarkedWordAddress(obj_end, ntams);
1478 }
1479
1480 // Mark the allocated-since-marking portion...
1481 HeapWord* top = hr->top();
1482 if (ntams < top) {
1483 BitMap::idx_t start_idx = _cm->card_bitmap_index_for(ntams);
1484 BitMap::idx_t end_idx = _cm->card_bitmap_index_for(top);
1485
1486 // Note: if we're looking at the last region in heap - top
1487 // could be actually just beyond the end of the heap; end_idx
1488 // will then correspond to a (non-existent) card that is also
1489 // just beyond the heap.
1490 if (_g1h->is_in_g1_reserved(top) && !_ct_bs->is_card_aligned(top)) {
1491 // end of object is not card aligned - increment to cover
1492 // all the cards spanned by the object
1493 end_idx += 1;
1494 }
1495 _cm->set_card_bitmap_range(_card_bm, start_idx, end_idx, true /* is_par */);
1496
1497 // This definitely means the region has live objects.
1498 set_bit_for_region(hr);
1499 }
1500
1501 // Update the live region bitmap.
1502 if (marked_bytes > 0) {
1503 set_bit_for_region(hr);
1504 }
1505
1506 // Set the marked bytes for the current region so that
1507 // it can be queried by a calling verification routine
1508 _region_marked_bytes = marked_bytes;
1509
1510 return false;
1511 }
1512
1513 size_t region_marked_bytes() const { return _region_marked_bytes; }
1514 };
1515
1516 // Heap region closure used for verifying the counting data
1517 // that was accumulated concurrently and aggregated during
1518 // the remark pause. This closure is applied to the heap
1519 // regions during the STW cleanup pause.
1520
1521 class VerifyLiveObjectDataHRClosure: public HeapRegionClosure {
1522 G1CollectedHeap* _g1h;
1523 ConcurrentMark* _cm;
1524 CalcLiveObjectsClosure _calc_cl;
1525 BitMap* _region_bm; // Region BM to be verified
1526 BitMap* _card_bm; // Card BM to be verified
1527 bool _verbose; // verbose output?
1528
1529 BitMap* _exp_region_bm; // Expected Region BM values
1530 BitMap* _exp_card_bm; // Expected card BM values
1531
1532 int _failures;
1533
1534 public:
1535 VerifyLiveObjectDataHRClosure(G1CollectedHeap* g1h,
1536 BitMap* region_bm,
1537 BitMap* card_bm,
1538 BitMap* exp_region_bm,
1539 BitMap* exp_card_bm,
1540 bool verbose) :
1541 _g1h(g1h), _cm(g1h->concurrent_mark()),
1542 _calc_cl(_cm->nextMarkBitMap(), g1h, exp_region_bm, exp_card_bm),
1543 _region_bm(region_bm), _card_bm(card_bm), _verbose(verbose),
1544 _exp_region_bm(exp_region_bm), _exp_card_bm(exp_card_bm),
1545 _failures(0) { }
1546
1547 int failures() const { return _failures; }
1548
1549 bool doHeapRegion(HeapRegion* hr) {
1550 if (hr->continuesHumongous()) {
1551 // We will ignore these here and process them when their
1552 // associated "starts humongous" region is processed (see
1553 // set_bit_for_heap_region()). Note that we cannot rely on their
1554 // associated "starts humongous" region to have their bit set to
1555 // 1 since, due to the region chunking in the parallel region
1556 // iteration, a "continues humongous" region might be visited
1557 // before its associated "starts humongous".
1558 return false;
1559 }
1560
1561 int failures = 0;
1562
1563 // Call the CalcLiveObjectsClosure to walk the marking bitmap for
1564 // this region and set the corresponding bits in the expected region
1565 // and card bitmaps.
1566 bool res = _calc_cl.doHeapRegion(hr);
1567 assert(res == false, "should be continuing");
1568
1569 MutexLockerEx x((_verbose ? ParGCRareEvent_lock : NULL),
1570 Mutex::_no_safepoint_check_flag);
1571
1572 // Verify the marked bytes for this region.
1573 size_t exp_marked_bytes = _calc_cl.region_marked_bytes();
1574 size_t act_marked_bytes = hr->next_marked_bytes();
1575
1576 // We're not OK if expected marked bytes > actual marked bytes. It means
1577 // we have missed accounting some objects during the actual marking.
1578 if (exp_marked_bytes > act_marked_bytes) {
1579 if (_verbose) {
1580 gclog_or_tty->print_cr("Region %u: marked bytes mismatch: "
1581 "expected: " SIZE_FORMAT ", actual: " SIZE_FORMAT,
1582 hr->hrm_index(), exp_marked_bytes, act_marked_bytes);
1583 }
1584 failures += 1;
1585 }
1586
1587 // Verify the bit, for this region, in the actual and expected
1588 // (which was just calculated) region bit maps.
1589 // We're not OK if the bit in the calculated expected region
1590 // bitmap is set and the bit in the actual region bitmap is not.
1591 BitMap::idx_t index = (BitMap::idx_t) hr->hrm_index();
1592
1593 bool expected = _exp_region_bm->at(index);
1594 bool actual = _region_bm->at(index);
1595 if (expected && !actual) {
1596 if (_verbose) {
1597 gclog_or_tty->print_cr("Region %u: region bitmap mismatch: "
1598 "expected: %s, actual: %s",
1599 hr->hrm_index(),
1600 BOOL_TO_STR(expected), BOOL_TO_STR(actual));
1601 }
1602 failures += 1;
1603 }
1604
1605 // Verify that the card bit maps for the cards spanned by the current
1606 // region match. We have an error if we have a set bit in the expected
1607 // bit map and the corresponding bit in the actual bitmap is not set.
1608
1609 BitMap::idx_t start_idx = _cm->card_bitmap_index_for(hr->bottom());
1610 BitMap::idx_t end_idx = _cm->card_bitmap_index_for(hr->top());
1611
1612 for (BitMap::idx_t i = start_idx; i < end_idx; i+=1) {
1613 expected = _exp_card_bm->at(i);
1614 actual = _card_bm->at(i);
1615
1616 if (expected && !actual) {
1617 if (_verbose) {
1618 gclog_or_tty->print_cr("Region %u: card bitmap mismatch at " SIZE_FORMAT ": "
1619 "expected: %s, actual: %s",
1620 hr->hrm_index(), i,
1621 BOOL_TO_STR(expected), BOOL_TO_STR(actual));
1622 }
1623 failures += 1;
1624 }
1625 }
1626
1627 if (failures > 0 && _verbose) {
1628 gclog_or_tty->print_cr("Region " HR_FORMAT ", ntams: " PTR_FORMAT ", "
1629 "marked_bytes: calc/actual " SIZE_FORMAT "/" SIZE_FORMAT,
1630 HR_FORMAT_PARAMS(hr), p2i(hr->next_top_at_mark_start()),
1631 _calc_cl.region_marked_bytes(), hr->next_marked_bytes());
1632 }
1633
1634 _failures += failures;
1635
1636 // We could stop iteration over the heap when we
1637 // find the first violating region by returning true.
1638 return false;
1639 }
1640 };
1641
1642 class G1ParVerifyFinalCountTask: public AbstractGangTask {
1643 protected:
1644 G1CollectedHeap* _g1h;
1645 ConcurrentMark* _cm;
1646 BitMap* _actual_region_bm;
1647 BitMap* _actual_card_bm;
1648
1649 uint _n_workers;
1650
1651 BitMap* _expected_region_bm;
1652 BitMap* _expected_card_bm;
1653
1654 int _failures;
1655 bool _verbose;
1656
1657 public:
1658 G1ParVerifyFinalCountTask(G1CollectedHeap* g1h,
1659 BitMap* region_bm, BitMap* card_bm,
1660 BitMap* expected_region_bm, BitMap* expected_card_bm)
1661 : AbstractGangTask("G1 verify final counting"),
1662 _g1h(g1h), _cm(_g1h->concurrent_mark()),
1663 _actual_region_bm(region_bm), _actual_card_bm(card_bm),
1664 _expected_region_bm(expected_region_bm), _expected_card_bm(expected_card_bm),
1665 _failures(0), _verbose(false),
1666 _n_workers(0) {
1667 assert(VerifyDuringGC, "don't call this otherwise");
1668
1669 // Use the value already set as the number of active threads
1670 // in the call to run_task().
1671 if (G1CollectedHeap::use_parallel_gc_threads()) {
1672 assert( _g1h->workers()->active_workers() > 0,
1673 "Should have been previously set");
1674 _n_workers = _g1h->workers()->active_workers();
1675 } else {
1676 _n_workers = 1;
1677 }
1678
1679 assert(_expected_card_bm->size() == _actual_card_bm->size(), "sanity");
1680 assert(_expected_region_bm->size() == _actual_region_bm->size(), "sanity");
1681
1682 _verbose = _cm->verbose_medium();
1683 }
1684
1685 void work(uint worker_id) {
1686 assert(worker_id < _n_workers, "invariant");
1687
1688 VerifyLiveObjectDataHRClosure verify_cl(_g1h,
1689 _actual_region_bm, _actual_card_bm,
1690 _expected_region_bm,
1691 _expected_card_bm,
1692 _verbose);
1693
1694 if (G1CollectedHeap::use_parallel_gc_threads()) {
1695 _g1h->heap_region_par_iterate_chunked(&verify_cl,
1696 worker_id,
1697 _n_workers,
1698 HeapRegion::VerifyCountClaimValue);
1699 } else {
1700 _g1h->heap_region_iterate(&verify_cl);
1701 }
1702
1703 Atomic::add(verify_cl.failures(), &_failures);
1704 }
1705
1706 int failures() const { return _failures; }
1707 };
1708
1709 // Closure that finalizes the liveness counting data.
1710 // Used during the cleanup pause.
1711 // Sets the bits corresponding to the interval [NTAMS, top]
1712 // (which contains the implicitly live objects) in the
1713 // card liveness bitmap. Also sets the bit for each region,
1714 // containing live data, in the region liveness bitmap.
1715
1716 class FinalCountDataUpdateClosure: public CMCountDataClosureBase {
1717 public:
1718 FinalCountDataUpdateClosure(G1CollectedHeap* g1h,
1719 BitMap* region_bm,
1720 BitMap* card_bm) :
1721 CMCountDataClosureBase(g1h, region_bm, card_bm) { }
1722
1723 bool doHeapRegion(HeapRegion* hr) {
1724
1725 if (hr->continuesHumongous()) {
1726 // We will ignore these here and process them when their
1727 // associated "starts humongous" region is processed (see
1728 // set_bit_for_heap_region()). Note that we cannot rely on their
1729 // associated "starts humongous" region to have their bit set to
1730 // 1 since, due to the region chunking in the parallel region
1731 // iteration, a "continues humongous" region might be visited
1732 // before its associated "starts humongous".
1733 return false;
1734 }
1735
1736 HeapWord* ntams = hr->next_top_at_mark_start();
1737 HeapWord* top = hr->top();
1738
1739 assert(hr->bottom() <= ntams && ntams <= hr->end(), "Preconditions.");
1740
1741 // Mark the allocated-since-marking portion...
1742 if (ntams < top) {
1743 // This definitely means the region has live objects.
1744 set_bit_for_region(hr);
1745
1746 // Now set the bits in the card bitmap for [ntams, top)
1747 BitMap::idx_t start_idx = _cm->card_bitmap_index_for(ntams);
1748 BitMap::idx_t end_idx = _cm->card_bitmap_index_for(top);
1749
1750 // Note: if we're looking at the last region in heap - top
1751 // could be actually just beyond the end of the heap; end_idx
1752 // will then correspond to a (non-existent) card that is also
1753 // just beyond the heap.
1754 if (_g1h->is_in_g1_reserved(top) && !_ct_bs->is_card_aligned(top)) {
1755 // end of object is not card aligned - increment to cover
1756 // all the cards spanned by the object
1757 end_idx += 1;
1758 }
1759
1760 assert(end_idx <= _card_bm->size(),
1761 err_msg("oob: end_idx= "SIZE_FORMAT", bitmap size= "SIZE_FORMAT,
1762 end_idx, _card_bm->size()));
1763 assert(start_idx < _card_bm->size(),
1764 err_msg("oob: start_idx= "SIZE_FORMAT", bitmap size= "SIZE_FORMAT,
1765 start_idx, _card_bm->size()));
1766
1767 _cm->set_card_bitmap_range(_card_bm, start_idx, end_idx, true /* is_par */);
1768 }
1769
1770 // Set the bit for the region if it contains live data
1771 if (hr->next_marked_bytes() > 0) {
1772 set_bit_for_region(hr);
1773 }
1774
1775 return false;
1776 }
1777 };
1778
1779 class G1ParFinalCountTask: public AbstractGangTask {
1780 protected:
1781 G1CollectedHeap* _g1h;
1782 ConcurrentMark* _cm;
1783 BitMap* _actual_region_bm;
1784 BitMap* _actual_card_bm;
1785
1786 uint _n_workers;
1787
1788 public:
1789 G1ParFinalCountTask(G1CollectedHeap* g1h, BitMap* region_bm, BitMap* card_bm)
1790 : AbstractGangTask("G1 final counting"),
1791 _g1h(g1h), _cm(_g1h->concurrent_mark()),
1792 _actual_region_bm(region_bm), _actual_card_bm(card_bm),
1793 _n_workers(0) {
1794 // Use the value already set as the number of active threads
1795 // in the call to run_task().
1796 if (G1CollectedHeap::use_parallel_gc_threads()) {
1797 assert( _g1h->workers()->active_workers() > 0,
1798 "Should have been previously set");
1799 _n_workers = _g1h->workers()->active_workers();
1800 } else {
1801 _n_workers = 1;
1802 }
1803 }
1804
1805 void work(uint worker_id) {
1806 assert(worker_id < _n_workers, "invariant");
1807
1808 FinalCountDataUpdateClosure final_update_cl(_g1h,
1809 _actual_region_bm,
1810 _actual_card_bm);
1811
1812 if (G1CollectedHeap::use_parallel_gc_threads()) {
1813 _g1h->heap_region_par_iterate_chunked(&final_update_cl,
1814 worker_id,
1815 _n_workers,
1816 HeapRegion::FinalCountClaimValue);
1817 } else {
1818 _g1h->heap_region_iterate(&final_update_cl);
1819 }
1820 }
1821 };
1822
1823 class G1ParNoteEndTask;
1824
1825 class G1NoteEndOfConcMarkClosure : public HeapRegionClosure {
1826 G1CollectedHeap* _g1;
1827 size_t _max_live_bytes;
1828 uint _regions_claimed;
1829 size_t _freed_bytes;
1830 FreeRegionList* _local_cleanup_list;
1831 HeapRegionSetCount _old_regions_removed;
1832 HeapRegionSetCount _humongous_regions_removed;
1833 HRRSCleanupTask* _hrrs_cleanup_task;
1834 double _claimed_region_time;
1835 double _max_region_time;
1836
1837 public:
1838 G1NoteEndOfConcMarkClosure(G1CollectedHeap* g1,
1839 FreeRegionList* local_cleanup_list,
1840 HRRSCleanupTask* hrrs_cleanup_task) :
1841 _g1(g1),
1842 _max_live_bytes(0), _regions_claimed(0),
1843 _freed_bytes(0),
1844 _claimed_region_time(0.0), _max_region_time(0.0),
1845 _local_cleanup_list(local_cleanup_list),
1846 _old_regions_removed(),
1847 _humongous_regions_removed(),
1848 _hrrs_cleanup_task(hrrs_cleanup_task) { }
1849
1850 size_t freed_bytes() { return _freed_bytes; }
1851 const HeapRegionSetCount& old_regions_removed() { return _old_regions_removed; }
1852 const HeapRegionSetCount& humongous_regions_removed() { return _humongous_regions_removed; }
1853
1854 bool doHeapRegion(HeapRegion *hr) {
1855 if (hr->continuesHumongous()) {
1856 return false;
1857 }
1858 // We use a claim value of zero here because all regions
1859 // were claimed with value 1 in the FinalCount task.
1860 _g1->reset_gc_time_stamps(hr);
1861 double start = os::elapsedTime();
1862 _regions_claimed++;
1863 hr->note_end_of_marking();
1864 _max_live_bytes += hr->max_live_bytes();
1865
1866 if (hr->used() > 0 && hr->max_live_bytes() == 0 && !hr->is_young()) {
1867 _freed_bytes += hr->used();
1868 hr->set_containing_set(NULL);
1869 if (hr->isHumongous()) {
1870 assert(hr->startsHumongous(), "we should only see starts humongous");
1871 _humongous_regions_removed.increment(1u, hr->capacity());
1872 _g1->free_humongous_region(hr, _local_cleanup_list, true);
1873 } else {
1874 _old_regions_removed.increment(1u, hr->capacity());
1875 _g1->free_region(hr, _local_cleanup_list, true);
1876 }
1877 } else {
1878 hr->rem_set()->do_cleanup_work(_hrrs_cleanup_task);
1879 }
1880
1881 double region_time = (os::elapsedTime() - start);
1882 _claimed_region_time += region_time;
1883 if (region_time > _max_region_time) {
1884 _max_region_time = region_time;
1885 }
1886 return false;
1887 }
1888
1889 size_t max_live_bytes() { return _max_live_bytes; }
1890 uint regions_claimed() { return _regions_claimed; }
1891 double claimed_region_time_sec() { return _claimed_region_time; }
1892 double max_region_time_sec() { return _max_region_time; }
1893 };
1894
1895 class G1ParNoteEndTask: public AbstractGangTask {
1896 friend class G1NoteEndOfConcMarkClosure;
1897
1898 protected:
1899 G1CollectedHeap* _g1h;
1900 size_t _max_live_bytes;
1901 size_t _freed_bytes;
1902 FreeRegionList* _cleanup_list;
1903
1904 public:
1905 G1ParNoteEndTask(G1CollectedHeap* g1h,
1906 FreeRegionList* cleanup_list) :
1907 AbstractGangTask("G1 note end"), _g1h(g1h),
1908 _max_live_bytes(0), _freed_bytes(0), _cleanup_list(cleanup_list) { }
1909
1910 void work(uint worker_id) {
1911 double start = os::elapsedTime();
1912 FreeRegionList local_cleanup_list("Local Cleanup List");
1913 HRRSCleanupTask hrrs_cleanup_task;
1914 G1NoteEndOfConcMarkClosure g1_note_end(_g1h, &local_cleanup_list,
1915 &hrrs_cleanup_task);
1916 if (G1CollectedHeap::use_parallel_gc_threads()) {
1917 _g1h->heap_region_par_iterate_chunked(&g1_note_end, worker_id,
1918 _g1h->workers()->active_workers(),
1919 HeapRegion::NoteEndClaimValue);
1920 } else {
1921 _g1h->heap_region_iterate(&g1_note_end);
1922 }
1923 assert(g1_note_end.complete(), "Shouldn't have yielded!");
1924
1925 // Now update the lists
1926 _g1h->remove_from_old_sets(g1_note_end.old_regions_removed(), g1_note_end.humongous_regions_removed());
1927 {
1928 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
1929 _g1h->decrement_summary_bytes(g1_note_end.freed_bytes());
1930 _max_live_bytes += g1_note_end.max_live_bytes();
1931 _freed_bytes += g1_note_end.freed_bytes();
1932
1933 // If we iterate over the global cleanup list at the end of
1934 // cleanup to do this printing we will not guarantee to only
1935 // generate output for the newly-reclaimed regions (the list
1936 // might not be empty at the beginning of cleanup; we might
1937 // still be working on its previous contents). So we do the
1938 // printing here, before we append the new regions to the global
1939 // cleanup list.
1940
1941 G1HRPrinter* hr_printer = _g1h->hr_printer();
1942 if (hr_printer->is_active()) {
1943 FreeRegionListIterator iter(&local_cleanup_list);
1944 while (iter.more_available()) {
1945 HeapRegion* hr = iter.get_next();
1946 hr_printer->cleanup(hr);
1947 }
1948 }
1949
1950 _cleanup_list->add_ordered(&local_cleanup_list);
1951 assert(local_cleanup_list.is_empty(), "post-condition");
1952
1953 HeapRegionRemSet::finish_cleanup_task(&hrrs_cleanup_task);
1954 }
1955 }
1956 size_t max_live_bytes() { return _max_live_bytes; }
1957 size_t freed_bytes() { return _freed_bytes; }
1958 };
1959
1960 class G1ParScrubRemSetTask: public AbstractGangTask {
1961 protected:
1962 G1RemSet* _g1rs;
1963 BitMap* _region_bm;
1964 BitMap* _card_bm;
1965 public:
1966 G1ParScrubRemSetTask(G1CollectedHeap* g1h,
1967 BitMap* region_bm, BitMap* card_bm) :
1968 AbstractGangTask("G1 ScrubRS"), _g1rs(g1h->g1_rem_set()),
1969 _region_bm(region_bm), _card_bm(card_bm) { }
1970
1971 void work(uint worker_id) {
1972 if (G1CollectedHeap::use_parallel_gc_threads()) {
1973 _g1rs->scrub_par(_region_bm, _card_bm, worker_id,
1974 HeapRegion::ScrubRemSetClaimValue);
1975 } else {
1976 _g1rs->scrub(_region_bm, _card_bm);
1977 }
1978 }
1979
1980 };
1981
1982 void ConcurrentMark::cleanup() {
1983 // world is stopped at this checkpoint
1984 assert(SafepointSynchronize::is_at_safepoint(),
1985 "world should be stopped");
1986 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1987
1988 // If a full collection has happened, we shouldn't do this.
1989 if (has_aborted()) {
1990 g1h->set_marking_complete(); // So bitmap clearing isn't confused
1991 return;
1992 }
1993
1994 g1h->verify_region_sets_optional();
1995
1996 if (VerifyDuringGC) {
1997 HandleMark hm; // handle scope
1998 Universe::heap()->prepare_for_verify();
1999 Universe::verify(VerifyOption_G1UsePrevMarking,
2000 " VerifyDuringGC:(before)");
2001 }
2002 g1h->check_bitmaps("Cleanup Start");
2003
2004 G1CollectorPolicy* g1p = G1CollectedHeap::heap()->g1_policy();
2005 g1p->record_concurrent_mark_cleanup_start();
2006
2007 double start = os::elapsedTime();
2008
2009 HeapRegionRemSet::reset_for_cleanup_tasks();
2010
2011 uint n_workers;
2012
2013 // Do counting once more with the world stopped for good measure.
2014 G1ParFinalCountTask g1_par_count_task(g1h, &_region_bm, &_card_bm);
2015
2016 if (G1CollectedHeap::use_parallel_gc_threads()) {
2017 assert(g1h->check_heap_region_claim_values(HeapRegion::InitialClaimValue),
2018 "sanity check");
2019
2020 g1h->set_par_threads();
2021 n_workers = g1h->n_par_threads();
2022 assert(g1h->n_par_threads() == n_workers,
2023 "Should not have been reset");
2024 g1h->workers()->run_task(&g1_par_count_task);
2025 // Done with the parallel phase so reset to 0.
2026 g1h->set_par_threads(0);
2027
2028 assert(g1h->check_heap_region_claim_values(HeapRegion::FinalCountClaimValue),
2029 "sanity check");
2030 } else {
2031 n_workers = 1;
2032 g1_par_count_task.work(0);
2033 }
2034
2035 if (VerifyDuringGC) {
2036 // Verify that the counting data accumulated during marking matches
2037 // that calculated by walking the marking bitmap.
2038
2039 // Bitmaps to hold expected values
2040 BitMap expected_region_bm(_region_bm.size(), true);
2041 BitMap expected_card_bm(_card_bm.size(), true);
2042
2043 G1ParVerifyFinalCountTask g1_par_verify_task(g1h,
2044 &_region_bm,
2045 &_card_bm,
2046 &expected_region_bm,
2047 &expected_card_bm);
2048
2049 if (G1CollectedHeap::use_parallel_gc_threads()) {
2050 g1h->set_par_threads((int)n_workers);
2051 g1h->workers()->run_task(&g1_par_verify_task);
2052 // Done with the parallel phase so reset to 0.
2053 g1h->set_par_threads(0);
2054
2055 assert(g1h->check_heap_region_claim_values(HeapRegion::VerifyCountClaimValue),
2056 "sanity check");
2057 } else {
2058 g1_par_verify_task.work(0);
2059 }
2060
2061 guarantee(g1_par_verify_task.failures() == 0, "Unexpected accounting failures");
2062 }
2063
2064 size_t start_used_bytes = g1h->used();
2065 g1h->set_marking_complete();
2066
2067 double count_end = os::elapsedTime();
2068 double this_final_counting_time = (count_end - start);
2069 _total_counting_time += this_final_counting_time;
2070
2071 if (G1PrintRegionLivenessInfo) {
2072 G1PrintRegionLivenessInfoClosure cl(gclog_or_tty, "Post-Marking");
2073 _g1h->heap_region_iterate(&cl);
2074 }
2075
2076 // Install newly created mark bitMap as "prev".
2077 swapMarkBitMaps();
2078
2079 g1h->reset_gc_time_stamp();
2080
2081 // Note end of marking in all heap regions.
2082 G1ParNoteEndTask g1_par_note_end_task(g1h, &_cleanup_list);
2083 if (G1CollectedHeap::use_parallel_gc_threads()) {
2084 g1h->set_par_threads((int)n_workers);
2085 g1h->workers()->run_task(&g1_par_note_end_task);
2086 g1h->set_par_threads(0);
2087
2088 assert(g1h->check_heap_region_claim_values(HeapRegion::NoteEndClaimValue),
2089 "sanity check");
2090 } else {
2091 g1_par_note_end_task.work(0);
2092 }
2093 g1h->check_gc_time_stamps();
2094
2095 if (!cleanup_list_is_empty()) {
2096 // The cleanup list is not empty, so we'll have to process it
2097 // concurrently. Notify anyone else that might be wanting free
2098 // regions that there will be more free regions coming soon.
2099 g1h->set_free_regions_coming();
2100 }
2101
2102 // call below, since it affects the metric by which we sort the heap
2103 // regions.
2104 if (G1ScrubRemSets) {
2105 double rs_scrub_start = os::elapsedTime();
2106 G1ParScrubRemSetTask g1_par_scrub_rs_task(g1h, &_region_bm, &_card_bm);
2107 if (G1CollectedHeap::use_parallel_gc_threads()) {
2108 g1h->set_par_threads((int)n_workers);
2109 g1h->workers()->run_task(&g1_par_scrub_rs_task);
2110 g1h->set_par_threads(0);
2111
2112 assert(g1h->check_heap_region_claim_values(
2113 HeapRegion::ScrubRemSetClaimValue),
2114 "sanity check");
2115 } else {
2116 g1_par_scrub_rs_task.work(0);
2117 }
2118
2119 double rs_scrub_end = os::elapsedTime();
2120 double this_rs_scrub_time = (rs_scrub_end - rs_scrub_start);
2121 _total_rs_scrub_time += this_rs_scrub_time;
2122 }
2123
2124 // this will also free any regions totally full of garbage objects,
2125 // and sort the regions.
2126 g1h->g1_policy()->record_concurrent_mark_cleanup_end((int)n_workers);
2127
2128 // Statistics.
2129 double end = os::elapsedTime();
2130 _cleanup_times.add((end - start) * 1000.0);
2131
2132 if (G1Log::fine()) {
2133 g1h->print_size_transition(gclog_or_tty,
2134 start_used_bytes,
2135 g1h->used(),
2136 g1h->capacity());
2137 }
2138
2139 // Clean up will have freed any regions completely full of garbage.
2140 // Update the soft reference policy with the new heap occupancy.
2141 Universe::update_heap_info_at_gc();
2142
2143 if (VerifyDuringGC) {
2144 HandleMark hm; // handle scope
2145 Universe::heap()->prepare_for_verify();
2146 Universe::verify(VerifyOption_G1UsePrevMarking,
2147 " VerifyDuringGC:(after)");
2148 }
2149
2150 g1h->check_bitmaps("Cleanup End");
2151
2152 g1h->verify_region_sets_optional();
2153
2154 // We need to make this be a "collection" so any collection pause that
2155 // races with it goes around and waits for completeCleanup to finish.
2156 g1h->increment_total_collections();
2157
2158 // Clean out dead classes and update Metaspace sizes.
2159 if (ClassUnloadingWithConcurrentMark) {
2160 ClassLoaderDataGraph::purge();
2161 }
2162 MetaspaceGC::compute_new_size();
2163
2164 // We reclaimed old regions so we should calculate the sizes to make
2165 // sure we update the old gen/space data.
2166 g1h->g1mm()->update_sizes();
2167
2168 g1h->trace_heap_after_concurrent_cycle();
2169 }
2170
2171 void ConcurrentMark::completeCleanup() {
2172 if (has_aborted()) return;
2173
2174 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2175
2176 _cleanup_list.verify_optional();
2177 FreeRegionList tmp_free_list("Tmp Free List");
2178
2179 if (G1ConcRegionFreeingVerbose) {
2180 gclog_or_tty->print_cr("G1ConcRegionFreeing [complete cleanup] : "
2181 "cleanup list has %u entries",
2182 _cleanup_list.length());
2183 }
2184
2185 // No one else should be accessing the _cleanup_list at this point,
2186 // so it is not necessary to take any locks
2187 while (!_cleanup_list.is_empty()) {
2188 HeapRegion* hr = _cleanup_list.remove_region(true /* from_head */);
2189 assert(hr != NULL, "Got NULL from a non-empty list");
2190 hr->par_clear();
2191 tmp_free_list.add_ordered(hr);
2192
2193 // Instead of adding one region at a time to the secondary_free_list,
2194 // we accumulate them in the local list and move them a few at a
2195 // time. This also cuts down on the number of notify_all() calls
2196 // we do during this process. We'll also append the local list when
2197 // _cleanup_list is empty (which means we just removed the last
2198 // region from the _cleanup_list).
2199 if ((tmp_free_list.length() % G1SecondaryFreeListAppendLength == 0) ||
2200 _cleanup_list.is_empty()) {
2201 if (G1ConcRegionFreeingVerbose) {
2202 gclog_or_tty->print_cr("G1ConcRegionFreeing [complete cleanup] : "
2203 "appending %u entries to the secondary_free_list, "
2204 "cleanup list still has %u entries",
2205 tmp_free_list.length(),
2206 _cleanup_list.length());
2207 }
2208
2209 {
2210 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
2211 g1h->secondary_free_list_add(&tmp_free_list);
2212 SecondaryFreeList_lock->notify_all();
2213 }
2214
2215 if (G1StressConcRegionFreeing) {
2216 for (uintx i = 0; i < G1StressConcRegionFreeingDelayMillis; ++i) {
2217 os::sleep(Thread::current(), (jlong) 1, false);
2218 }
2219 }
2220 }
2221 }
2222 assert(tmp_free_list.is_empty(), "post-condition");
2223 }
2224
2225 // Supporting Object and Oop closures for reference discovery
2226 // and processing in during marking
2227
2228 bool G1CMIsAliveClosure::do_object_b(oop obj) {
2229 HeapWord* addr = (HeapWord*)obj;
2230 return addr != NULL &&
2231 (!_g1->is_in_g1_reserved(addr) || !_g1->is_obj_ill(obj));
2232 }
2233
2234 // 'Keep Alive' oop closure used by both serial parallel reference processing.
2235 // Uses the CMTask associated with a worker thread (for serial reference
2236 // processing the CMTask for worker 0 is used) to preserve (mark) and
2237 // trace referent objects.
2238 //
2239 // Using the CMTask and embedded local queues avoids having the worker
2240 // threads operating on the global mark stack. This reduces the risk
2241 // of overflowing the stack - which we would rather avoid at this late
2242 // state. Also using the tasks' local queues removes the potential
2243 // of the workers interfering with each other that could occur if
2244 // operating on the global stack.
2245
2246 class G1CMKeepAliveAndDrainClosure: public OopClosure {
2247 ConcurrentMark* _cm;
2248 CMTask* _task;
2249 int _ref_counter_limit;
2250 int _ref_counter;
2251 bool _is_serial;
2252 public:
2253 G1CMKeepAliveAndDrainClosure(ConcurrentMark* cm, CMTask* task, bool is_serial) :
2254 _cm(cm), _task(task), _is_serial(is_serial),
2255 _ref_counter_limit(G1RefProcDrainInterval) {
2256 assert(_ref_counter_limit > 0, "sanity");
2257 assert(!_is_serial || _task->worker_id() == 0, "only task 0 for serial code");
2258 _ref_counter = _ref_counter_limit;
2259 }
2260
2261 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
2262 virtual void do_oop( oop* p) { do_oop_work(p); }
2263
2264 template <class T> void do_oop_work(T* p) {
2265 if (!_cm->has_overflown()) {
2266 oop obj = oopDesc::load_decode_heap_oop(p);
2267 if (_cm->verbose_high()) {
2268 gclog_or_tty->print_cr("\t[%u] we're looking at location "
2269 "*"PTR_FORMAT" = "PTR_FORMAT,
2270 _task->worker_id(), p2i(p), p2i((void*) obj));
2271 }
2272
2273 _task->deal_with_reference(obj);
2274 _ref_counter--;
2275
2276 if (_ref_counter == 0) {
2277 // We have dealt with _ref_counter_limit references, pushing them
2278 // and objects reachable from them on to the local stack (and
2279 // possibly the global stack). Call CMTask::do_marking_step() to
2280 // process these entries.
2281 //
2282 // We call CMTask::do_marking_step() in a loop, which we'll exit if
2283 // there's nothing more to do (i.e. we're done with the entries that
2284 // were pushed as a result of the CMTask::deal_with_reference() calls
2285 // above) or we overflow.
2286 //
2287 // Note: CMTask::do_marking_step() can set the CMTask::has_aborted()
2288 // flag while there may still be some work to do. (See the comment at
2289 // the beginning of CMTask::do_marking_step() for those conditions -
2290 // one of which is reaching the specified time target.) It is only
2291 // when CMTask::do_marking_step() returns without setting the
2292 // has_aborted() flag that the marking step has completed.
2293 do {
2294 double mark_step_duration_ms = G1ConcMarkStepDurationMillis;
2295 _task->do_marking_step(mark_step_duration_ms,
2296 false /* do_termination */,
2297 _is_serial);
2298 } while (_task->has_aborted() && !_cm->has_overflown());
2299 _ref_counter = _ref_counter_limit;
2300 }
2301 } else {
2302 if (_cm->verbose_high()) {
2303 gclog_or_tty->print_cr("\t[%u] CM Overflow", _task->worker_id());
2304 }
2305 }
2306 }
2307 };
2308
2309 // 'Drain' oop closure used by both serial and parallel reference processing.
2310 // Uses the CMTask associated with a given worker thread (for serial
2311 // reference processing the CMtask for worker 0 is used). Calls the
2312 // do_marking_step routine, with an unbelievably large timeout value,
2313 // to drain the marking data structures of the remaining entries
2314 // added by the 'keep alive' oop closure above.
2315
2316 class G1CMDrainMarkingStackClosure: public VoidClosure {
2317 ConcurrentMark* _cm;
2318 CMTask* _task;
2319 bool _is_serial;
2320 public:
2321 G1CMDrainMarkingStackClosure(ConcurrentMark* cm, CMTask* task, bool is_serial) :
2322 _cm(cm), _task(task), _is_serial(is_serial) {
2323 assert(!_is_serial || _task->worker_id() == 0, "only task 0 for serial code");
2324 }
2325
2326 void do_void() {
2327 do {
2328 if (_cm->verbose_high()) {
2329 gclog_or_tty->print_cr("\t[%u] Drain: Calling do_marking_step - serial: %s",
2330 _task->worker_id(), BOOL_TO_STR(_is_serial));
2331 }
2332
2333 // We call CMTask::do_marking_step() to completely drain the local
2334 // and global marking stacks of entries pushed by the 'keep alive'
2335 // oop closure (an instance of G1CMKeepAliveAndDrainClosure above).
2336 //
2337 // CMTask::do_marking_step() is called in a loop, which we'll exit
2338 // if there's nothing more to do (i.e. we've completely drained the
2339 // entries that were pushed as a a result of applying the 'keep alive'
2340 // closure to the entries on the discovered ref lists) or we overflow
2341 // the global marking stack.
2342 //
2343 // Note: CMTask::do_marking_step() can set the CMTask::has_aborted()
2344 // flag while there may still be some work to do. (See the comment at
2345 // the beginning of CMTask::do_marking_step() for those conditions -
2346 // one of which is reaching the specified time target.) It is only
2347 // when CMTask::do_marking_step() returns without setting the
2348 // has_aborted() flag that the marking step has completed.
2349
2350 _task->do_marking_step(1000000000.0 /* something very large */,
2351 true /* do_termination */,
2352 _is_serial);
2353 } while (_task->has_aborted() && !_cm->has_overflown());
2354 }
2355 };
2356
2357 // Implementation of AbstractRefProcTaskExecutor for parallel
2358 // reference processing at the end of G1 concurrent marking
2359
2360 class G1CMRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
2361 private:
2362 G1CollectedHeap* _g1h;
2363 ConcurrentMark* _cm;
2364 WorkGang* _workers;
2365 int _active_workers;
2366
2367 public:
2368 G1CMRefProcTaskExecutor(G1CollectedHeap* g1h,
2369 ConcurrentMark* cm,
2370 WorkGang* workers,
2371 int n_workers) :
2372 _g1h(g1h), _cm(cm),
2373 _workers(workers), _active_workers(n_workers) { }
2374
2375 // Executes the given task using concurrent marking worker threads.
2376 virtual void execute(ProcessTask& task);
2377 virtual void execute(EnqueueTask& task);
2378 };
2379
2380 class G1CMRefProcTaskProxy: public AbstractGangTask {
2381 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
2382 ProcessTask& _proc_task;
2383 G1CollectedHeap* _g1h;
2384 ConcurrentMark* _cm;
2385
2386 public:
2387 G1CMRefProcTaskProxy(ProcessTask& proc_task,
2388 G1CollectedHeap* g1h,
2389 ConcurrentMark* cm) :
2390 AbstractGangTask("Process reference objects in parallel"),
2391 _proc_task(proc_task), _g1h(g1h), _cm(cm) {
2392 ReferenceProcessor* rp = _g1h->ref_processor_cm();
2393 assert(rp->processing_is_mt(), "shouldn't be here otherwise");
2394 }
2395
2396 virtual void work(uint worker_id) {
2397 ResourceMark rm;
2398 HandleMark hm;
2399 CMTask* task = _cm->task(worker_id);
2400 G1CMIsAliveClosure g1_is_alive(_g1h);
2401 G1CMKeepAliveAndDrainClosure g1_par_keep_alive(_cm, task, false /* is_serial */);
2402 G1CMDrainMarkingStackClosure g1_par_drain(_cm, task, false /* is_serial */);
2403
2404 _proc_task.work(worker_id, g1_is_alive, g1_par_keep_alive, g1_par_drain);
2405 }
2406 };
2407
2408 void G1CMRefProcTaskExecutor::execute(ProcessTask& proc_task) {
2409 assert(_workers != NULL, "Need parallel worker threads.");
2410 assert(_g1h->ref_processor_cm()->processing_is_mt(), "processing is not MT");
2411
2412 G1CMRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _cm);
2413
2414 // We need to reset the concurrency level before each
2415 // proxy task execution, so that the termination protocol
2416 // and overflow handling in CMTask::do_marking_step() knows
2417 // how many workers to wait for.
2418 _cm->set_concurrency(_active_workers);
2419 _g1h->set_par_threads(_active_workers);
2420 _workers->run_task(&proc_task_proxy);
2421 _g1h->set_par_threads(0);
2422 }
2423
2424 class G1CMRefEnqueueTaskProxy: public AbstractGangTask {
2425 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
2426 EnqueueTask& _enq_task;
2427
2428 public:
2429 G1CMRefEnqueueTaskProxy(EnqueueTask& enq_task) :
2430 AbstractGangTask("Enqueue reference objects in parallel"),
2431 _enq_task(enq_task) { }
2432
2433 virtual void work(uint worker_id) {
2434 _enq_task.work(worker_id);
2435 }
2436 };
2437
2438 void G1CMRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
2439 assert(_workers != NULL, "Need parallel worker threads.");
2440 assert(_g1h->ref_processor_cm()->processing_is_mt(), "processing is not MT");
2441
2442 G1CMRefEnqueueTaskProxy enq_task_proxy(enq_task);
2443
2444 // Not strictly necessary but...
2445 //
2446 // We need to reset the concurrency level before each
2447 // proxy task execution, so that the termination protocol
2448 // and overflow handling in CMTask::do_marking_step() knows
2449 // how many workers to wait for.
2450 _cm->set_concurrency(_active_workers);
2451 _g1h->set_par_threads(_active_workers);
2452 _workers->run_task(&enq_task_proxy);
2453 _g1h->set_par_threads(0);
2454 }
2455
2456 void ConcurrentMark::weakRefsWorkParallelPart(BoolObjectClosure* is_alive, bool purged_classes) {
2457 G1CollectedHeap::heap()->parallel_cleaning(is_alive, true, true, purged_classes);
2458 }
2459
2460 // Helper class to get rid of some boilerplate code.
2461 class G1RemarkGCTraceTime : public GCTraceTime {
2462 static bool doit_and_prepend(bool doit) {
2463 if (doit) {
2464 gclog_or_tty->put(' ');
2465 }
2466 return doit;
2467 }
2468
2469 public:
2470 G1RemarkGCTraceTime(const char* title, bool doit)
2471 : GCTraceTime(title, doit_and_prepend(doit), false, G1CollectedHeap::heap()->gc_timer_cm(),
2472 G1CollectedHeap::heap()->concurrent_mark()->concurrent_gc_id()) {
2473 }
2474 };
2475
2476 void ConcurrentMark::weakRefsWork(bool clear_all_soft_refs) {
2477 if (has_overflown()) {
2478 // Skip processing the discovered references if we have
2479 // overflown the global marking stack. Reference objects
2480 // only get discovered once so it is OK to not
2481 // de-populate the discovered reference lists. We could have,
2482 // but the only benefit would be that, when marking restarts,
2483 // less reference objects are discovered.
2484 return;
2485 }
2486
2487 ResourceMark rm;
2488 HandleMark hm;
2489
2490 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2491
2492 // Is alive closure.
2493 G1CMIsAliveClosure g1_is_alive(g1h);
2494
2495 // Inner scope to exclude the cleaning of the string and symbol
2496 // tables from the displayed time.
2497 {
2498 if (G1Log::finer()) {
2499 gclog_or_tty->put(' ');
2500 }
2501 GCTraceTime t("GC ref-proc", G1Log::finer(), false, g1h->gc_timer_cm(), concurrent_gc_id());
2502
2503 ReferenceProcessor* rp = g1h->ref_processor_cm();
2504
2505 // See the comment in G1CollectedHeap::ref_processing_init()
2506 // about how reference processing currently works in G1.
2507
2508 // Set the soft reference policy
2509 rp->setup_policy(clear_all_soft_refs);
2510 assert(_markStack.isEmpty(), "mark stack should be empty");
2511
2512 // Instances of the 'Keep Alive' and 'Complete GC' closures used
2513 // in serial reference processing. Note these closures are also
2514 // used for serially processing (by the the current thread) the
2515 // JNI references during parallel reference processing.
2516 //
2517 // These closures do not need to synchronize with the worker
2518 // threads involved in parallel reference processing as these
2519 // instances are executed serially by the current thread (e.g.
2520 // reference processing is not multi-threaded and is thus
2521 // performed by the current thread instead of a gang worker).
2522 //
2523 // The gang tasks involved in parallel reference processing create
2524 // their own instances of these closures, which do their own
2525 // synchronization among themselves.
2526 G1CMKeepAliveAndDrainClosure g1_keep_alive(this, task(0), true /* is_serial */);
2527 G1CMDrainMarkingStackClosure g1_drain_mark_stack(this, task(0), true /* is_serial */);
2528
2529 // We need at least one active thread. If reference processing
2530 // is not multi-threaded we use the current (VMThread) thread,
2531 // otherwise we use the work gang from the G1CollectedHeap and
2532 // we utilize all the worker threads we can.
2533 bool processing_is_mt = rp->processing_is_mt() && g1h->workers() != NULL;
2534 uint active_workers = (processing_is_mt ? g1h->workers()->active_workers() : 1U);
2535 active_workers = MAX2(MIN2(active_workers, _max_worker_id), 1U);
2536
2537 // Parallel processing task executor.
2538 G1CMRefProcTaskExecutor par_task_executor(g1h, this,
2539 g1h->workers(), active_workers);
2540 AbstractRefProcTaskExecutor* executor = (processing_is_mt ? &par_task_executor : NULL);
2541
2542 // Set the concurrency level. The phase was already set prior to
2543 // executing the remark task.
2544 set_concurrency(active_workers);
2545
2546 // Set the degree of MT processing here. If the discovery was done MT,
2547 // the number of threads involved during discovery could differ from
2548 // the number of active workers. This is OK as long as the discovered
2549 // Reference lists are balanced (see balance_all_queues() and balance_queues()).
2550 rp->set_active_mt_degree(active_workers);
2551
2552 // Process the weak references.
2553 const ReferenceProcessorStats& stats =
2554 rp->process_discovered_references(&g1_is_alive,
2555 &g1_keep_alive,
2556 &g1_drain_mark_stack,
2557 executor,
2558 g1h->gc_timer_cm(),
2559 concurrent_gc_id());
2560 g1h->gc_tracer_cm()->report_gc_reference_stats(stats);
2561
2562 // The do_oop work routines of the keep_alive and drain_marking_stack
2563 // oop closures will set the has_overflown flag if we overflow the
2564 // global marking stack.
2565
2566 assert(_markStack.overflow() || _markStack.isEmpty(),
2567 "mark stack should be empty (unless it overflowed)");
2568
2569 if (_markStack.overflow()) {
2570 // This should have been done already when we tried to push an
2571 // entry on to the global mark stack. But let's do it again.
2572 set_has_overflown();
2573 }
2574
2575 assert(rp->num_q() == active_workers, "why not");
2576
2577 rp->enqueue_discovered_references(executor);
2578
2579 rp->verify_no_references_recorded();
2580 assert(!rp->discovery_enabled(), "Post condition");
2581 }
2582
2583 if (has_overflown()) {
2584 // We can not trust g1_is_alive if the marking stack overflowed
2585 return;
2586 }
2587
2588 assert(_markStack.isEmpty(), "Marking should have completed");
2589
2590 // Unload Klasses, String, Symbols, Code Cache, etc.
2591 {
2592 G1RemarkGCTraceTime trace("Unloading", G1Log::finer());
2593
2594 if (ClassUnloadingWithConcurrentMark) {
2595 bool purged_classes;
2596
2597 {
2598 G1RemarkGCTraceTime trace("System Dictionary Unloading", G1Log::finest());
2599 purged_classes = SystemDictionary::do_unloading(&g1_is_alive);
2600 }
2601
2602 {
2603 G1RemarkGCTraceTime trace("Parallel Unloading", G1Log::finest());
2604 weakRefsWorkParallelPart(&g1_is_alive, purged_classes);
2605 }
2606 }
2607
2608 if (G1StringDedup::is_enabled()) {
2609 G1RemarkGCTraceTime trace("String Deduplication Unlink", G1Log::finest());
2610 G1StringDedup::unlink(&g1_is_alive);
2611 }
2612 }
2613 }
2614
2615 void ConcurrentMark::swapMarkBitMaps() {
2616 CMBitMapRO* temp = _prevMarkBitMap;
2617 _prevMarkBitMap = (CMBitMapRO*)_nextMarkBitMap;
2618 _nextMarkBitMap = (CMBitMap*) temp;
2619 }
2620
2621 class CMObjectClosure;
2622
2623 // Closure for iterating over objects, currently only used for
2624 // processing SATB buffers.
2625 class CMObjectClosure : public ObjectClosure {
2626 private:
2627 CMTask* _task;
2628
2629 public:
2630 void do_object(oop obj) {
2631 _task->deal_with_reference(obj);
2632 }
2633
2634 CMObjectClosure(CMTask* task) : _task(task) { }
2635 };
2636
2637 class G1RemarkThreadsClosure : public ThreadClosure {
2638 CMObjectClosure _cm_obj;
2639 G1CMOopClosure _cm_cl;
2640 MarkingCodeBlobClosure _code_cl;
2641 int _thread_parity;
2642 bool _is_par;
2643
2644 public:
2645 G1RemarkThreadsClosure(G1CollectedHeap* g1h, CMTask* task, bool is_par) :
2646 _cm_obj(task), _cm_cl(g1h, g1h->concurrent_mark(), task), _code_cl(&_cm_cl, !CodeBlobToOopClosure::FixRelocations),
2647 _thread_parity(SharedHeap::heap()->strong_roots_parity()), _is_par(is_par) {}
2648
2649 void do_thread(Thread* thread) {
2650 if (thread->is_Java_thread()) {
2651 if (thread->claim_oops_do(_is_par, _thread_parity)) {
2652 JavaThread* jt = (JavaThread*)thread;
2653
2654 // In theory it should not be neccessary to explicitly walk the nmethods to find roots for concurrent marking
2655 // however the liveness of oops reachable from nmethods have very complex lifecycles:
2656 // * Alive if on the stack of an executing method
2657 // * Weakly reachable otherwise
2658 // Some objects reachable from nmethods, such as the class loader (or klass_holder) of the receiver should be
2659 // live by the SATB invariant but other oops recorded in nmethods may behave differently.
2660 jt->nmethods_do(&_code_cl);
2661
2662 jt->satb_mark_queue().apply_closure_and_empty(&_cm_obj);
2663 }
2664 } else if (thread->is_VM_thread()) {
2665 if (thread->claim_oops_do(_is_par, _thread_parity)) {
2666 JavaThread::satb_mark_queue_set().shared_satb_queue()->apply_closure_and_empty(&_cm_obj);
2667 }
2668 }
2669 }
2670 };
2671
2672 class CMRemarkTask: public AbstractGangTask {
2673 private:
2674 ConcurrentMark* _cm;
2675 bool _is_serial;
2676 public:
2677 void work(uint worker_id) {
2678 // Since all available tasks are actually started, we should
2679 // only proceed if we're supposed to be active.
2680 if (worker_id < _cm->active_tasks()) {
2681 CMTask* task = _cm->task(worker_id);
2682 task->record_start_time();
2683 {
2684 ResourceMark rm;
2685 HandleMark hm;
2686
2687 G1RemarkThreadsClosure threads_f(G1CollectedHeap::heap(), task, !_is_serial);
2688 Threads::threads_do(&threads_f);
2689 }
2690
2691 do {
2692 task->do_marking_step(1000000000.0 /* something very large */,
2693 true /* do_termination */,
2694 _is_serial);
2695 } while (task->has_aborted() && !_cm->has_overflown());
2696 // If we overflow, then we do not want to restart. We instead
2697 // want to abort remark and do concurrent marking again.
2698 task->record_end_time();
2699 }
2700 }
2701
2702 CMRemarkTask(ConcurrentMark* cm, int active_workers, bool is_serial) :
2703 AbstractGangTask("Par Remark"), _cm(cm), _is_serial(is_serial) {
2704 _cm->terminator()->reset_for_reuse(active_workers);
2705 }
2706 };
2707
2708 void ConcurrentMark::checkpointRootsFinalWork() {
2709 ResourceMark rm;
2710 HandleMark hm;
2711 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2712
2713 G1RemarkGCTraceTime trace("Finalize Marking", G1Log::finer());
2714
2715 g1h->ensure_parsability(false);
2716
2717 if (G1CollectedHeap::use_parallel_gc_threads()) {
2718 G1CollectedHeap::StrongRootsScope srs(g1h);
2719 // this is remark, so we'll use up all active threads
2720 uint active_workers = g1h->workers()->active_workers();
2721 if (active_workers == 0) {
2722 assert(active_workers > 0, "Should have been set earlier");
2723 active_workers = (uint) ParallelGCThreads;
2724 g1h->workers()->set_active_workers(active_workers);
2725 }
2726 set_concurrency_and_phase(active_workers, false /* concurrent */);
2727 // Leave _parallel_marking_threads at it's
2728 // value originally calculated in the ConcurrentMark
2729 // constructor and pass values of the active workers
2730 // through the gang in the task.
2731
2732 CMRemarkTask remarkTask(this, active_workers, false /* is_serial */);
2733 // We will start all available threads, even if we decide that the
2734 // active_workers will be fewer. The extra ones will just bail out
2735 // immediately.
2736 g1h->set_par_threads(active_workers);
2737 g1h->workers()->run_task(&remarkTask);
2738 g1h->set_par_threads(0);
2739 } else {
2740 G1CollectedHeap::StrongRootsScope srs(g1h);
2741 uint active_workers = 1;
2742 set_concurrency_and_phase(active_workers, false /* concurrent */);
2743
2744 // Note - if there's no work gang then the VMThread will be
2745 // the thread to execute the remark - serially. We have
2746 // to pass true for the is_serial parameter so that
2747 // CMTask::do_marking_step() doesn't enter the sync
2748 // barriers in the event of an overflow. Doing so will
2749 // cause an assert that the current thread is not a
2750 // concurrent GC thread.
2751 CMRemarkTask remarkTask(this, active_workers, true /* is_serial*/);
2752 remarkTask.work(0);
2753 }
2754 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
2755 guarantee(has_overflown() ||
2756 satb_mq_set.completed_buffers_num() == 0,
2757 err_msg("Invariant: has_overflown = %s, num buffers = %d",
2758 BOOL_TO_STR(has_overflown()),
2759 satb_mq_set.completed_buffers_num()));
2760
2761 print_stats();
2762 }
2763
2764 #ifndef PRODUCT
2765
2766 class PrintReachableOopClosure: public OopClosure {
2767 private:
2768 G1CollectedHeap* _g1h;
2769 outputStream* _out;
2770 VerifyOption _vo;
2771 bool _all;
2772
2773 public:
2774 PrintReachableOopClosure(outputStream* out,
2775 VerifyOption vo,
2776 bool all) :
2777 _g1h(G1CollectedHeap::heap()),
2778 _out(out), _vo(vo), _all(all) { }
2779
2780 void do_oop(narrowOop* p) { do_oop_work(p); }
2781 void do_oop( oop* p) { do_oop_work(p); }
2782
2783 template <class T> void do_oop_work(T* p) {
2784 oop obj = oopDesc::load_decode_heap_oop(p);
2785 const char* str = NULL;
2786 const char* str2 = "";
2787
2788 if (obj == NULL) {
2789 str = "";
2790 } else if (!_g1h->is_in_g1_reserved(obj)) {
2791 str = " O";
2792 } else {
2793 HeapRegion* hr = _g1h->heap_region_containing(obj);
2794 bool over_tams = _g1h->allocated_since_marking(obj, hr, _vo);
2795 bool marked = _g1h->is_marked(obj, _vo);
2796
2797 if (over_tams) {
2798 str = " >";
2799 if (marked) {
2800 str2 = " AND MARKED";
2801 }
2802 } else if (marked) {
2803 str = " M";
2804 } else {
2805 str = " NOT";
2806 }
2807 }
2808
2809 _out->print_cr(" "PTR_FORMAT": "PTR_FORMAT"%s%s",
2810 p2i(p), p2i((void*) obj), str, str2);
2811 }
2812 };
2813
2814 class PrintReachableObjectClosure : public ObjectClosure {
2815 private:
2816 G1CollectedHeap* _g1h;
2817 outputStream* _out;
2818 VerifyOption _vo;
2819 bool _all;
2820 HeapRegion* _hr;
2821
2822 public:
2823 PrintReachableObjectClosure(outputStream* out,
2824 VerifyOption vo,
2825 bool all,
2826 HeapRegion* hr) :
2827 _g1h(G1CollectedHeap::heap()),
2828 _out(out), _vo(vo), _all(all), _hr(hr) { }
2829
2830 void do_object(oop o) {
2831 bool over_tams = _g1h->allocated_since_marking(o, _hr, _vo);
2832 bool marked = _g1h->is_marked(o, _vo);
2833 bool print_it = _all || over_tams || marked;
2834
2835 if (print_it) {
2836 _out->print_cr(" "PTR_FORMAT"%s",
2837 p2i((void *)o), (over_tams) ? " >" : (marked) ? " M" : "");
2838 PrintReachableOopClosure oopCl(_out, _vo, _all);
2839 o->oop_iterate_no_header(&oopCl);
2840 }
2841 }
2842 };
2843
2844 class PrintReachableRegionClosure : public HeapRegionClosure {
2845 private:
2846 G1CollectedHeap* _g1h;
2847 outputStream* _out;
2848 VerifyOption _vo;
2849 bool _all;
2850
2851 public:
2852 bool doHeapRegion(HeapRegion* hr) {
2853 HeapWord* b = hr->bottom();
2854 HeapWord* e = hr->end();
2855 HeapWord* t = hr->top();
2856 HeapWord* p = _g1h->top_at_mark_start(hr, _vo);
2857 _out->print_cr("** ["PTR_FORMAT", "PTR_FORMAT"] top: "PTR_FORMAT" "
2858 "TAMS: " PTR_FORMAT, p2i(b), p2i(e), p2i(t), p2i(p));
2859 _out->cr();
2860
2861 HeapWord* from = b;
2862 HeapWord* to = t;
2863
2864 if (to > from) {
2865 _out->print_cr("Objects in [" PTR_FORMAT ", " PTR_FORMAT "]", p2i(from), p2i(to));
2866 _out->cr();
2867 PrintReachableObjectClosure ocl(_out, _vo, _all, hr);
2868 hr->object_iterate_mem_careful(MemRegion(from, to), &ocl);
2869 _out->cr();
2870 }
2871
2872 return false;
2873 }
2874
2875 PrintReachableRegionClosure(outputStream* out,
2876 VerifyOption vo,
2877 bool all) :
2878 _g1h(G1CollectedHeap::heap()), _out(out), _vo(vo), _all(all) { }
2879 };
2880
2881 void ConcurrentMark::print_reachable(const char* str,
2882 VerifyOption vo,
2883 bool all) {
2884 gclog_or_tty->cr();
2885 gclog_or_tty->print_cr("== Doing heap dump... ");
2886
2887 if (G1PrintReachableBaseFile == NULL) {
2888 gclog_or_tty->print_cr(" #### error: no base file defined");
2889 return;
2890 }
2891
2892 if (strlen(G1PrintReachableBaseFile) + 1 + strlen(str) >
2893 (JVM_MAXPATHLEN - 1)) {
2894 gclog_or_tty->print_cr(" #### error: file name too long");
2895 return;
2896 }
2897
2898 char file_name[JVM_MAXPATHLEN];
2899 sprintf(file_name, "%s.%s", G1PrintReachableBaseFile, str);
2900 gclog_or_tty->print_cr(" dumping to file %s", file_name);
2901
2902 fileStream fout(file_name);
2903 if (!fout.is_open()) {
2904 gclog_or_tty->print_cr(" #### error: could not open file");
2905 return;
2906 }
2907
2908 outputStream* out = &fout;
2909 out->print_cr("-- USING %s", _g1h->top_at_mark_start_str(vo));
2910 out->cr();
2911
2912 out->print_cr("--- ITERATING OVER REGIONS");
2913 out->cr();
2914 PrintReachableRegionClosure rcl(out, vo, all);
2915 _g1h->heap_region_iterate(&rcl);
2916 out->cr();
2917
2918 gclog_or_tty->print_cr(" done");
2919 gclog_or_tty->flush();
2920 }
2921
2922 #endif // PRODUCT
2923
2924 void ConcurrentMark::clearRangePrevBitmap(MemRegion mr) {
2925 // Note we are overriding the read-only view of the prev map here, via
2926 // the cast.
2927 ((CMBitMap*)_prevMarkBitMap)->clearRange(mr);
2928 }
2929
2930 void ConcurrentMark::clearRangeNextBitmap(MemRegion mr) {
2931 _nextMarkBitMap->clearRange(mr);
2932 }
2933
2934 HeapRegion*
2935 ConcurrentMark::claim_region(uint worker_id) {
2936 // "checkpoint" the finger
2937 HeapWord* finger = _finger;
2938
2939 // _heap_end will not change underneath our feet; it only changes at
2940 // yield points.
2941 while (finger < _heap_end) {
2942 assert(_g1h->is_in_g1_reserved(finger), "invariant");
2943
2944 // Note on how this code handles humongous regions. In the
2945 // normal case the finger will reach the start of a "starts
2946 // humongous" (SH) region. Its end will either be the end of the
2947 // last "continues humongous" (CH) region in the sequence, or the
2948 // standard end of the SH region (if the SH is the only region in
2949 // the sequence). That way claim_region() will skip over the CH
2950 // regions. However, there is a subtle race between a CM thread
2951 // executing this method and a mutator thread doing a humongous
2952 // object allocation. The two are not mutually exclusive as the CM
2953 // thread does not need to hold the Heap_lock when it gets
2954 // here. So there is a chance that claim_region() will come across
2955 // a free region that's in the progress of becoming a SH or a CH
2956 // region. In the former case, it will either
2957 // a) Miss the update to the region's end, in which case it will
2958 // visit every subsequent CH region, will find their bitmaps
2959 // empty, and do nothing, or
2960 // b) Will observe the update of the region's end (in which case
2961 // it will skip the subsequent CH regions).
2962 // If it comes across a region that suddenly becomes CH, the
2963 // scenario will be similar to b). So, the race between
2964 // claim_region() and a humongous object allocation might force us
2965 // to do a bit of unnecessary work (due to some unnecessary bitmap
2966 // iterations) but it should not introduce and correctness issues.
2967 HeapRegion* curr_region = _g1h->heap_region_containing_raw(finger);
2968
2969 // Above heap_region_containing_raw may return NULL as we always scan claim
2970 // until the end of the heap. In this case, just jump to the next region.
2971 HeapWord* end = curr_region != NULL ? curr_region->end() : finger + HeapRegion::GrainWords;
2972
2973 // Is the gap between reading the finger and doing the CAS too long?
2974 HeapWord* res = (HeapWord*) Atomic::cmpxchg_ptr(end, &_finger, finger);
2975 if (res == finger && curr_region != NULL) {
2976 // we succeeded
2977 HeapWord* bottom = curr_region->bottom();
2978 HeapWord* limit = curr_region->next_top_at_mark_start();
2979
2980 if (verbose_low()) {
2981 gclog_or_tty->print_cr("[%u] curr_region = "PTR_FORMAT" "
2982 "["PTR_FORMAT", "PTR_FORMAT"), "
2983 "limit = "PTR_FORMAT,
2984 worker_id, p2i(curr_region), p2i(bottom), p2i(end), p2i(limit));
2985 }
2986
2987 // notice that _finger == end cannot be guaranteed here since,
2988 // someone else might have moved the finger even further
2989 assert(_finger >= end, "the finger should have moved forward");
2990
2991 if (verbose_low()) {
2992 gclog_or_tty->print_cr("[%u] we were successful with region = "
2993 PTR_FORMAT, worker_id, p2i(curr_region));
2994 }
2995
2996 if (limit > bottom) {
2997 if (verbose_low()) {
2998 gclog_or_tty->print_cr("[%u] region "PTR_FORMAT" is not empty, "
2999 "returning it ", worker_id, p2i(curr_region));
3000 }
3001 return curr_region;
3002 } else {
3003 assert(limit == bottom,
3004 "the region limit should be at bottom");
3005 if (verbose_low()) {
3006 gclog_or_tty->print_cr("[%u] region "PTR_FORMAT" is empty, "
3007 "returning NULL", worker_id, p2i(curr_region));
3008 }
3009 // we return NULL and the caller should try calling
3010 // claim_region() again.
3011 return NULL;
3012 }
3013 } else {
3014 assert(_finger > finger, "the finger should have moved forward");
3015 if (verbose_low()) {
3016 if (curr_region == NULL) {
3017 gclog_or_tty->print_cr("[%u] found uncommitted region, moving finger, "
3018 "global finger = "PTR_FORMAT", "
3019 "our finger = "PTR_FORMAT,
3020 worker_id, p2i(_finger), p2i(finger));
3021 } else {
3022 gclog_or_tty->print_cr("[%u] somebody else moved the finger, "
3023 "global finger = "PTR_FORMAT", "
3024 "our finger = "PTR_FORMAT,
3025 worker_id, p2i(_finger), p2i(finger));
3026 }
3027 }
3028
3029 // read it again
3030 finger = _finger;
3031 }
3032 }
3033
3034 return NULL;
3035 }
3036
3037 #ifndef PRODUCT
3038 enum VerifyNoCSetOopsPhase {
3039 VerifyNoCSetOopsStack,
3040 VerifyNoCSetOopsQueues,
3041 VerifyNoCSetOopsSATBCompleted,
3042 VerifyNoCSetOopsSATBThread
3043 };
3044
3045 class VerifyNoCSetOopsClosure : public OopClosure, public ObjectClosure {
3046 private:
3047 G1CollectedHeap* _g1h;
3048 VerifyNoCSetOopsPhase _phase;
3049 int _info;
3050
3051 const char* phase_str() {
3052 switch (_phase) {
3053 case VerifyNoCSetOopsStack: return "Stack";
3054 case VerifyNoCSetOopsQueues: return "Queue";
3055 case VerifyNoCSetOopsSATBCompleted: return "Completed SATB Buffers";
3056 case VerifyNoCSetOopsSATBThread: return "Thread SATB Buffers";
3057 default: ShouldNotReachHere();
3058 }
3059 return NULL;
3060 }
3061
3062 void do_object_work(oop obj) {
3063 guarantee(!_g1h->obj_in_cs(obj),
3064 err_msg("obj: "PTR_FORMAT" in CSet, phase: %s, info: %d",
3065 p2i((void*) obj), phase_str(), _info));
3066 }
3067
3068 public:
3069 VerifyNoCSetOopsClosure() : _g1h(G1CollectedHeap::heap()) { }
3070
3071 void set_phase(VerifyNoCSetOopsPhase phase, int info = -1) {
3072 _phase = phase;
3073 _info = info;
3074 }
3075
3076 virtual void do_oop(oop* p) {
3077 oop obj = oopDesc::load_decode_heap_oop(p);
3078 do_object_work(obj);
3079 }
3080
3081 virtual void do_oop(narrowOop* p) {
3082 // We should not come across narrow oops while scanning marking
3083 // stacks and SATB buffers.
3084 ShouldNotReachHere();
3085 }
3086
3087 virtual void do_object(oop obj) {
3088 do_object_work(obj);
3089 }
3090 };
3091
3092 void ConcurrentMark::verify_no_cset_oops(bool verify_stacks,
3093 bool verify_enqueued_buffers,
3094 bool verify_thread_buffers,
3095 bool verify_fingers) {
3096 assert(SafepointSynchronize::is_at_safepoint(), "should be at a safepoint");
3097 if (!G1CollectedHeap::heap()->mark_in_progress()) {
3098 return;
3099 }
3100
3101 VerifyNoCSetOopsClosure cl;
3102
3103 if (verify_stacks) {
3104 // Verify entries on the global mark stack
3105 cl.set_phase(VerifyNoCSetOopsStack);
3106 _markStack.oops_do(&cl);
3107
3108 // Verify entries on the task queues
3109 for (uint i = 0; i < _max_worker_id; i += 1) {
3110 cl.set_phase(VerifyNoCSetOopsQueues, i);
3111 CMTaskQueue* queue = _task_queues->queue(i);
3112 queue->oops_do(&cl);
3113 }
3114 }
3115
3116 SATBMarkQueueSet& satb_qs = JavaThread::satb_mark_queue_set();
3117
3118 // Verify entries on the enqueued SATB buffers
3119 if (verify_enqueued_buffers) {
3120 cl.set_phase(VerifyNoCSetOopsSATBCompleted);
3121 satb_qs.iterate_completed_buffers_read_only(&cl);
3122 }
3123
3124 // Verify entries on the per-thread SATB buffers
3125 if (verify_thread_buffers) {
3126 cl.set_phase(VerifyNoCSetOopsSATBThread);
3127 satb_qs.iterate_thread_buffers_read_only(&cl);
3128 }
3129
3130 if (verify_fingers) {
3131 // Verify the global finger
3132 HeapWord* global_finger = finger();
3133 if (global_finger != NULL && global_finger < _heap_end) {
3134 // The global finger always points to a heap region boundary. We
3135 // use heap_region_containing_raw() to get the containing region
3136 // given that the global finger could be pointing to a free region
3137 // which subsequently becomes continues humongous. If that
3138 // happens, heap_region_containing() will return the bottom of the
3139 // corresponding starts humongous region and the check below will
3140 // not hold any more.
3141 // Since we always iterate over all regions, we might get a NULL HeapRegion
3142 // here.
3143 HeapRegion* global_hr = _g1h->heap_region_containing_raw(global_finger);
3144 guarantee(global_hr == NULL || global_finger == global_hr->bottom(),
3145 err_msg("global finger: "PTR_FORMAT" region: "HR_FORMAT,
3146 p2i(global_finger), HR_FORMAT_PARAMS(global_hr)));
3147 }
3148
3149 // Verify the task fingers
3150 assert(parallel_marking_threads() <= _max_worker_id, "sanity");
3151 for (int i = 0; i < (int) parallel_marking_threads(); i += 1) {
3152 CMTask* task = _tasks[i];
3153 HeapWord* task_finger = task->finger();
3154 if (task_finger != NULL && task_finger < _heap_end) {
3155 // See above note on the global finger verification.
3156 HeapRegion* task_hr = _g1h->heap_region_containing_raw(task_finger);
3157 guarantee(task_hr == NULL || task_finger == task_hr->bottom() ||
3158 !task_hr->in_collection_set(),
3159 err_msg("task finger: "PTR_FORMAT" region: "HR_FORMAT,
3160 p2i(task_finger), HR_FORMAT_PARAMS(task_hr)));
3161 }
3162 }
3163 }
3164 }
3165 #endif // PRODUCT
3166
3167 // Aggregate the counting data that was constructed concurrently
3168 // with marking.
3169 class AggregateCountDataHRClosure: public HeapRegionClosure {
3170 G1CollectedHeap* _g1h;
3171 ConcurrentMark* _cm;
3172 CardTableModRefBS* _ct_bs;
3173 BitMap* _cm_card_bm;
3174 uint _max_worker_id;
3175
3176 public:
3177 AggregateCountDataHRClosure(G1CollectedHeap* g1h,
3178 BitMap* cm_card_bm,
3179 uint max_worker_id) :
3180 _g1h(g1h), _cm(g1h->concurrent_mark()),
3181 _ct_bs((CardTableModRefBS*) (g1h->barrier_set())),
3182 _cm_card_bm(cm_card_bm), _max_worker_id(max_worker_id) { }
3183
3184 bool doHeapRegion(HeapRegion* hr) {
3185 if (hr->continuesHumongous()) {
3186 // We will ignore these here and process them when their
3187 // associated "starts humongous" region is processed.
3188 // Note that we cannot rely on their associated
3189 // "starts humongous" region to have their bit set to 1
3190 // since, due to the region chunking in the parallel region
3191 // iteration, a "continues humongous" region might be visited
3192 // before its associated "starts humongous".
3193 return false;
3194 }
3195
3196 HeapWord* start = hr->bottom();
3197 HeapWord* limit = hr->next_top_at_mark_start();
3198 HeapWord* end = hr->end();
3199
3200 assert(start <= limit && limit <= hr->top() && hr->top() <= hr->end(),
3201 err_msg("Preconditions not met - "
3202 "start: "PTR_FORMAT", limit: "PTR_FORMAT", "
3203 "top: "PTR_FORMAT", end: "PTR_FORMAT,
3204 p2i(start), p2i(limit), p2i(hr->top()), p2i(hr->end())));
3205
3206 assert(hr->next_marked_bytes() == 0, "Precondition");
3207
3208 if (start == limit) {
3209 // NTAMS of this region has not been set so nothing to do.
3210 return false;
3211 }
3212
3213 // 'start' should be in the heap.
3214 assert(_g1h->is_in_g1_reserved(start) && _ct_bs->is_card_aligned(start), "sanity");
3215 // 'end' *may* be just beyond the end of the heap (if hr is the last region)
3216 assert(!_g1h->is_in_g1_reserved(end) || _ct_bs->is_card_aligned(end), "sanity");
3217
3218 BitMap::idx_t start_idx = _cm->card_bitmap_index_for(start);
3219 BitMap::idx_t limit_idx = _cm->card_bitmap_index_for(limit);
3220 BitMap::idx_t end_idx = _cm->card_bitmap_index_for(end);
3221
3222 // If ntams is not card aligned then we bump card bitmap index
3223 // for limit so that we get the all the cards spanned by
3224 // the object ending at ntams.
3225 // Note: if this is the last region in the heap then ntams
3226 // could be actually just beyond the end of the the heap;
3227 // limit_idx will then correspond to a (non-existent) card
3228 // that is also outside the heap.
3229 if (_g1h->is_in_g1_reserved(limit) && !_ct_bs->is_card_aligned(limit)) {
3230 limit_idx += 1;
3231 }
3232
3233 assert(limit_idx <= end_idx, "or else use atomics");
3234
3235 // Aggregate the "stripe" in the count data associated with hr.
3236 uint hrm_index = hr->hrm_index();
3237 size_t marked_bytes = 0;
3238
3239 for (uint i = 0; i < _max_worker_id; i += 1) {
3240 size_t* marked_bytes_array = _cm->count_marked_bytes_array_for(i);
3241 BitMap* task_card_bm = _cm->count_card_bitmap_for(i);
3242
3243 // Fetch the marked_bytes in this region for task i and
3244 // add it to the running total for this region.
3245 marked_bytes += marked_bytes_array[hrm_index];
3246
3247 // Now union the bitmaps[0,max_worker_id)[start_idx..limit_idx)
3248 // into the global card bitmap.
3249 BitMap::idx_t scan_idx = task_card_bm->get_next_one_offset(start_idx, limit_idx);
3250
3251 while (scan_idx < limit_idx) {
3252 assert(task_card_bm->at(scan_idx) == true, "should be");
3253 _cm_card_bm->set_bit(scan_idx);
3254 assert(_cm_card_bm->at(scan_idx) == true, "should be");
3255
3256 // BitMap::get_next_one_offset() can handle the case when
3257 // its left_offset parameter is greater than its right_offset
3258 // parameter. It does, however, have an early exit if
3259 // left_offset == right_offset. So let's limit the value
3260 // passed in for left offset here.
3261 BitMap::idx_t next_idx = MIN2(scan_idx + 1, limit_idx);
3262 scan_idx = task_card_bm->get_next_one_offset(next_idx, limit_idx);
3263 }
3264 }
3265
3266 // Update the marked bytes for this region.
3267 hr->add_to_marked_bytes(marked_bytes);
3268
3269 // Next heap region
3270 return false;
3271 }
3272 };
3273
3274 class G1AggregateCountDataTask: public AbstractGangTask {
3275 protected:
3276 G1CollectedHeap* _g1h;
3277 ConcurrentMark* _cm;
3278 BitMap* _cm_card_bm;
3279 uint _max_worker_id;
3280 int _active_workers;
3281
3282 public:
3283 G1AggregateCountDataTask(G1CollectedHeap* g1h,
3284 ConcurrentMark* cm,
3285 BitMap* cm_card_bm,
3286 uint max_worker_id,
3287 int n_workers) :
3288 AbstractGangTask("Count Aggregation"),
3289 _g1h(g1h), _cm(cm), _cm_card_bm(cm_card_bm),
3290 _max_worker_id(max_worker_id),
3291 _active_workers(n_workers) { }
3292
3293 void work(uint worker_id) {
3294 AggregateCountDataHRClosure cl(_g1h, _cm_card_bm, _max_worker_id);
3295
3296 if (G1CollectedHeap::use_parallel_gc_threads()) {
3297 _g1h->heap_region_par_iterate_chunked(&cl, worker_id,
3298 _active_workers,
3299 HeapRegion::AggregateCountClaimValue);
3300 } else {
3301 _g1h->heap_region_iterate(&cl);
3302 }
3303 }
3304 };
3305
3306
3307 void ConcurrentMark::aggregate_count_data() {
3308 int n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
3309 _g1h->workers()->active_workers() :
3310 1);
3311
3312 G1AggregateCountDataTask g1_par_agg_task(_g1h, this, &_card_bm,
3313 _max_worker_id, n_workers);
3314
3315 if (G1CollectedHeap::use_parallel_gc_threads()) {
3316 assert(_g1h->check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3317 "sanity check");
3318 _g1h->set_par_threads(n_workers);
3319 _g1h->workers()->run_task(&g1_par_agg_task);
3320 _g1h->set_par_threads(0);
3321
3322 assert(_g1h->check_heap_region_claim_values(HeapRegion::AggregateCountClaimValue),
3323 "sanity check");
3324 _g1h->reset_heap_region_claim_values();
3325 } else {
3326 g1_par_agg_task.work(0);
3327 }
3328 }
3329
3330 // Clear the per-worker arrays used to store the per-region counting data
3331 void ConcurrentMark::clear_all_count_data() {
3332 // Clear the global card bitmap - it will be filled during
3333 // liveness count aggregation (during remark) and the
3334 // final counting task.
3335 _card_bm.clear();
3336
3337 // Clear the global region bitmap - it will be filled as part
3338 // of the final counting task.
3339 _region_bm.clear();
3340
3341 uint max_regions = _g1h->max_regions();
3342 assert(_max_worker_id > 0, "uninitialized");
3343
3344 for (uint i = 0; i < _max_worker_id; i += 1) {
3345 BitMap* task_card_bm = count_card_bitmap_for(i);
3346 size_t* marked_bytes_array = count_marked_bytes_array_for(i);
3347
3348 assert(task_card_bm->size() == _card_bm.size(), "size mismatch");
3349 assert(marked_bytes_array != NULL, "uninitialized");
3350
3351 memset(marked_bytes_array, 0, (size_t) max_regions * sizeof(size_t));
3352 task_card_bm->clear();
3353 }
3354 }
3355
3356 void ConcurrentMark::print_stats() {
3357 if (verbose_stats()) {
3358 gclog_or_tty->print_cr("---------------------------------------------------------------------");
3359 for (size_t i = 0; i < _active_tasks; ++i) {
3360 _tasks[i]->print_stats();
3361 gclog_or_tty->print_cr("---------------------------------------------------------------------");
3362 }
3363 }
3364 }
3365
3366 // abandon current marking iteration due to a Full GC
3367 void ConcurrentMark::abort() {
3368 // Clear all marks in the next bitmap for the next marking cycle. This will allow us to skip the next
3369 // concurrent bitmap clearing.
3370 _nextMarkBitMap->clearAll();
3371
3372 // Note we cannot clear the previous marking bitmap here
3373 // since VerifyDuringGC verifies the objects marked during
3374 // a full GC against the previous bitmap.
3375
3376 // Clear the liveness counting data
3377 clear_all_count_data();
3378 // Empty mark stack
3379 reset_marking_state();
3380 for (uint i = 0; i < _max_worker_id; ++i) {
3381 _tasks[i]->clear_region_fields();
3382 }
3383 _first_overflow_barrier_sync.abort();
3384 _second_overflow_barrier_sync.abort();
3385 const GCId& gc_id = _g1h->gc_tracer_cm()->gc_id();
3386 if (!gc_id.is_undefined()) {
3387 // We can do multiple full GCs before ConcurrentMarkThread::run() gets a chance
3388 // to detect that it was aborted. Only keep track of the first GC id that we aborted.
3389 _aborted_gc_id = gc_id;
3390 }
3391 _has_aborted = true;
3392
3393 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
3394 satb_mq_set.abandon_partial_marking();
3395 // This can be called either during or outside marking, we'll read
3396 // the expected_active value from the SATB queue set.
3397 satb_mq_set.set_active_all_threads(
3398 false, /* new active value */
3399 satb_mq_set.is_active() /* expected_active */);
3400
3401 _g1h->trace_heap_after_concurrent_cycle();
3402 _g1h->register_concurrent_cycle_end();
3403 }
3404
3405 const GCId& ConcurrentMark::concurrent_gc_id() {
3406 if (has_aborted()) {
3407 return _aborted_gc_id;
3408 }
3409 return _g1h->gc_tracer_cm()->gc_id();
3410 }
3411
3412 static void print_ms_time_info(const char* prefix, const char* name,
3413 NumberSeq& ns) {
3414 gclog_or_tty->print_cr("%s%5d %12s: total time = %8.2f s (avg = %8.2f ms).",
3415 prefix, ns.num(), name, ns.sum()/1000.0, ns.avg());
3416 if (ns.num() > 0) {
3417 gclog_or_tty->print_cr("%s [std. dev = %8.2f ms, max = %8.2f ms]",
3418 prefix, ns.sd(), ns.maximum());
3419 }
3420 }
3421
3422 void ConcurrentMark::print_summary_info() {
3423 gclog_or_tty->print_cr(" Concurrent marking:");
3424 print_ms_time_info(" ", "init marks", _init_times);
3425 print_ms_time_info(" ", "remarks", _remark_times);
3426 {
3427 print_ms_time_info(" ", "final marks", _remark_mark_times);
3428 print_ms_time_info(" ", "weak refs", _remark_weak_ref_times);
3429
3430 }
3431 print_ms_time_info(" ", "cleanups", _cleanup_times);
3432 gclog_or_tty->print_cr(" Final counting total time = %8.2f s (avg = %8.2f ms).",
3433 _total_counting_time,
3434 (_cleanup_times.num() > 0 ? _total_counting_time * 1000.0 /
3435 (double)_cleanup_times.num()
3436 : 0.0));
3437 if (G1ScrubRemSets) {
3438 gclog_or_tty->print_cr(" RS scrub total time = %8.2f s (avg = %8.2f ms).",
3439 _total_rs_scrub_time,
3440 (_cleanup_times.num() > 0 ? _total_rs_scrub_time * 1000.0 /
3441 (double)_cleanup_times.num()
3442 : 0.0));
3443 }
3444 gclog_or_tty->print_cr(" Total stop_world time = %8.2f s.",
3445 (_init_times.sum() + _remark_times.sum() +
3446 _cleanup_times.sum())/1000.0);
3447 gclog_or_tty->print_cr(" Total concurrent time = %8.2f s "
3448 "(%8.2f s marking).",
3449 cmThread()->vtime_accum(),
3450 cmThread()->vtime_mark_accum());
3451 }
3452
3453 void ConcurrentMark::print_worker_threads_on(outputStream* st) const {
3454 if (use_parallel_marking_threads()) {
3455 _parallel_workers->print_worker_threads_on(st);
3456 }
3457 }
3458
3459 void ConcurrentMark::print_on_error(outputStream* st) const {
3460 st->print_cr("Marking Bits (Prev, Next): (CMBitMap*) " PTR_FORMAT ", (CMBitMap*) " PTR_FORMAT,
3461 p2i(_prevMarkBitMap), p2i(_nextMarkBitMap));
3462 _prevMarkBitMap->print_on_error(st, " Prev Bits: ");
3463 _nextMarkBitMap->print_on_error(st, " Next Bits: ");
3464 }
3465
3466 // We take a break if someone is trying to stop the world.
3467 bool ConcurrentMark::do_yield_check(uint worker_id) {
3468 if (SuspendibleThreadSet::should_yield()) {
3469 if (worker_id == 0) {
3470 _g1h->g1_policy()->record_concurrent_pause();
3471 }
3472 SuspendibleThreadSet::yield();
3473 return true;
3474 } else {
3475 return false;
3476 }
3477 }
3478
3479 #ifndef PRODUCT
3480 // for debugging purposes
3481 void ConcurrentMark::print_finger() {
3482 gclog_or_tty->print_cr("heap ["PTR_FORMAT", "PTR_FORMAT"), global finger = "PTR_FORMAT,
3483 p2i(_heap_start), p2i(_heap_end), p2i(_finger));
3484 for (uint i = 0; i < _max_worker_id; ++i) {
3485 gclog_or_tty->print(" %u: " PTR_FORMAT, i, p2i(_tasks[i]->finger()));
3486 }
3487 gclog_or_tty->cr();
3488 }
3489 #endif
3490
3491 void CMTask::scan_object(oop obj) {
3492 assert(_nextMarkBitMap->isMarked((HeapWord*) obj), "invariant");
3493
3494 if (_cm->verbose_high()) {
3495 gclog_or_tty->print_cr("[%u] we're scanning object "PTR_FORMAT,
3496 _worker_id, p2i((void*) obj));
3497 }
3498
3499 size_t obj_size = obj->size();
3500 _words_scanned += obj_size;
3501
3502 obj->oop_iterate(_cm_oop_closure);
3503 statsOnly( ++_objs_scanned );
3504 check_limits();
3505 }
3506
3507 // Closure for iteration over bitmaps
3508 class CMBitMapClosure : public BitMapClosure {
3509 private:
3510 // the bitmap that is being iterated over
3511 CMBitMap* _nextMarkBitMap;
3512 ConcurrentMark* _cm;
3513 CMTask* _task;
3514
3515 public:
3516 CMBitMapClosure(CMTask *task, ConcurrentMark* cm, CMBitMap* nextMarkBitMap) :
3517 _task(task), _cm(cm), _nextMarkBitMap(nextMarkBitMap) { }
3518
3519 bool do_bit(size_t offset) {
3520 HeapWord* addr = _nextMarkBitMap->offsetToHeapWord(offset);
3521 assert(_nextMarkBitMap->isMarked(addr), "invariant");
3522 assert( addr < _cm->finger(), "invariant");
3523
3524 statsOnly( _task->increase_objs_found_on_bitmap() );
3525 assert(addr >= _task->finger(), "invariant");
3526
3527 // We move that task's local finger along.
3528 _task->move_finger_to(addr);
3529
3530 _task->scan_object(oop(addr));
3531 // we only partially drain the local queue and global stack
3532 _task->drain_local_queue(true);
3533 _task->drain_global_stack(true);
3534
3535 // if the has_aborted flag has been raised, we need to bail out of
3536 // the iteration
3537 return !_task->has_aborted();
3538 }
3539 };
3540
3541 G1CMOopClosure::G1CMOopClosure(G1CollectedHeap* g1h,
3542 ConcurrentMark* cm,
3543 CMTask* task)
3544 : _g1h(g1h), _cm(cm), _task(task) {
3545 assert(_ref_processor == NULL, "should be initialized to NULL");
3546
3547 if (G1UseConcMarkReferenceProcessing) {
3548 _ref_processor = g1h->ref_processor_cm();
3549 assert(_ref_processor != NULL, "should not be NULL");
3550 }
3551 }
3552
3553 void CMTask::setup_for_region(HeapRegion* hr) {
3554 assert(hr != NULL,
3555 "claim_region() should have filtered out NULL regions");
3556 assert(!hr->continuesHumongous(),
3557 "claim_region() should have filtered out continues humongous regions");
3558
3559 if (_cm->verbose_low()) {
3560 gclog_or_tty->print_cr("[%u] setting up for region "PTR_FORMAT,
3561 _worker_id, p2i(hr));
3562 }
3563
3564 _curr_region = hr;
3565 _finger = hr->bottom();
3566 update_region_limit();
3567 }
3568
3569 void CMTask::update_region_limit() {
3570 HeapRegion* hr = _curr_region;
3571 HeapWord* bottom = hr->bottom();
3572 HeapWord* limit = hr->next_top_at_mark_start();
3573
3574 if (limit == bottom) {
3575 if (_cm->verbose_low()) {
3576 gclog_or_tty->print_cr("[%u] found an empty region "
3577 "["PTR_FORMAT", "PTR_FORMAT")",
3578 _worker_id, p2i(bottom), p2i(limit));
3579 }
3580 // The region was collected underneath our feet.
3581 // We set the finger to bottom to ensure that the bitmap
3582 // iteration that will follow this will not do anything.
3583 // (this is not a condition that holds when we set the region up,
3584 // as the region is not supposed to be empty in the first place)
3585 _finger = bottom;
3586 } else if (limit >= _region_limit) {
3587 assert(limit >= _finger, "peace of mind");
3588 } else {
3589 assert(limit < _region_limit, "only way to get here");
3590 // This can happen under some pretty unusual circumstances. An
3591 // evacuation pause empties the region underneath our feet (NTAMS
3592 // at bottom). We then do some allocation in the region (NTAMS
3593 // stays at bottom), followed by the region being used as a GC
3594 // alloc region (NTAMS will move to top() and the objects
3595 // originally below it will be grayed). All objects now marked in
3596 // the region are explicitly grayed, if below the global finger,
3597 // and we do not need in fact to scan anything else. So, we simply
3598 // set _finger to be limit to ensure that the bitmap iteration
3599 // doesn't do anything.
3600 _finger = limit;
3601 }
3602
3603 _region_limit = limit;
3604 }
3605
3606 void CMTask::giveup_current_region() {
3607 assert(_curr_region != NULL, "invariant");
3608 if (_cm->verbose_low()) {
3609 gclog_or_tty->print_cr("[%u] giving up region "PTR_FORMAT,
3610 _worker_id, p2i(_curr_region));
3611 }
3612 clear_region_fields();
3613 }
3614
3615 void CMTask::clear_region_fields() {
3616 // Values for these three fields that indicate that we're not
3617 // holding on to a region.
3618 _curr_region = NULL;
3619 _finger = NULL;
3620 _region_limit = NULL;
3621 }
3622
3623 void CMTask::set_cm_oop_closure(G1CMOopClosure* cm_oop_closure) {
3624 if (cm_oop_closure == NULL) {
3625 assert(_cm_oop_closure != NULL, "invariant");
3626 } else {
3627 assert(_cm_oop_closure == NULL, "invariant");
3628 }
3629 _cm_oop_closure = cm_oop_closure;
3630 }
3631
3632 void CMTask::reset(CMBitMap* nextMarkBitMap) {
3633 guarantee(nextMarkBitMap != NULL, "invariant");
3634
3635 if (_cm->verbose_low()) {
3636 gclog_or_tty->print_cr("[%u] resetting", _worker_id);
3637 }
3638
3639 _nextMarkBitMap = nextMarkBitMap;
3640 clear_region_fields();
3641
3642 _calls = 0;
3643 _elapsed_time_ms = 0.0;
3644 _termination_time_ms = 0.0;
3645 _termination_start_time_ms = 0.0;
3646
3647 #if _MARKING_STATS_
3648 _local_pushes = 0;
3649 _local_pops = 0;
3650 _local_max_size = 0;
3651 _objs_scanned = 0;
3652 _global_pushes = 0;
3653 _global_pops = 0;
3654 _global_max_size = 0;
3655 _global_transfers_to = 0;
3656 _global_transfers_from = 0;
3657 _regions_claimed = 0;
3658 _objs_found_on_bitmap = 0;
3659 _satb_buffers_processed = 0;
3660 _steal_attempts = 0;
3661 _steals = 0;
3662 _aborted = 0;
3663 _aborted_overflow = 0;
3664 _aborted_cm_aborted = 0;
3665 _aborted_yield = 0;
3666 _aborted_timed_out = 0;
3667 _aborted_satb = 0;
3668 _aborted_termination = 0;
3669 #endif // _MARKING_STATS_
3670 }
3671
3672 bool CMTask::should_exit_termination() {
3673 regular_clock_call();
3674 // This is called when we are in the termination protocol. We should
3675 // quit if, for some reason, this task wants to abort or the global
3676 // stack is not empty (this means that we can get work from it).
3677 return !_cm->mark_stack_empty() || has_aborted();
3678 }
3679
3680 void CMTask::reached_limit() {
3681 assert(_words_scanned >= _words_scanned_limit ||
3682 _refs_reached >= _refs_reached_limit ,
3683 "shouldn't have been called otherwise");
3684 regular_clock_call();
3685 }
3686
3687 void CMTask::regular_clock_call() {
3688 if (has_aborted()) return;
3689
3690 // First, we need to recalculate the words scanned and refs reached
3691 // limits for the next clock call.
3692 recalculate_limits();
3693
3694 // During the regular clock call we do the following
3695
3696 // (1) If an overflow has been flagged, then we abort.
3697 if (_cm->has_overflown()) {
3698 set_has_aborted();
3699 return;
3700 }
3701
3702 // If we are not concurrent (i.e. we're doing remark) we don't need
3703 // to check anything else. The other steps are only needed during
3704 // the concurrent marking phase.
3705 if (!concurrent()) return;
3706
3707 // (2) If marking has been aborted for Full GC, then we also abort.
3708 if (_cm->has_aborted()) {
3709 set_has_aborted();
3710 statsOnly( ++_aborted_cm_aborted );
3711 return;
3712 }
3713
3714 double curr_time_ms = os::elapsedVTime() * 1000.0;
3715
3716 // (3) If marking stats are enabled, then we update the step history.
3717 #if _MARKING_STATS_
3718 if (_words_scanned >= _words_scanned_limit) {
3719 ++_clock_due_to_scanning;
3720 }
3721 if (_refs_reached >= _refs_reached_limit) {
3722 ++_clock_due_to_marking;
3723 }
3724
3725 double last_interval_ms = curr_time_ms - _interval_start_time_ms;
3726 _interval_start_time_ms = curr_time_ms;
3727 _all_clock_intervals_ms.add(last_interval_ms);
3728
3729 if (_cm->verbose_medium()) {
3730 gclog_or_tty->print_cr("[%u] regular clock, interval = %1.2lfms, "
3731 "scanned = "SIZE_FORMAT"%s, refs reached = "SIZE_FORMAT"%s",
3732 _worker_id, last_interval_ms,
3733 _words_scanned,
3734 (_words_scanned >= _words_scanned_limit) ? " (*)" : "",
3735 _refs_reached,
3736 (_refs_reached >= _refs_reached_limit) ? " (*)" : "");
3737 }
3738 #endif // _MARKING_STATS_
3739
3740 // (4) We check whether we should yield. If we have to, then we abort.
3741 if (SuspendibleThreadSet::should_yield()) {
3742 // We should yield. To do this we abort the task. The caller is
3743 // responsible for yielding.
3744 set_has_aborted();
3745 statsOnly( ++_aborted_yield );
3746 return;
3747 }
3748
3749 // (5) We check whether we've reached our time quota. If we have,
3750 // then we abort.
3751 double elapsed_time_ms = curr_time_ms - _start_time_ms;
3752 if (elapsed_time_ms > _time_target_ms) {
3753 set_has_aborted();
3754 _has_timed_out = true;
3755 statsOnly( ++_aborted_timed_out );
3756 return;
3757 }
3758
3759 // (6) Finally, we check whether there are enough completed STAB
3760 // buffers available for processing. If there are, we abort.
3761 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
3762 if (!_draining_satb_buffers && satb_mq_set.process_completed_buffers()) {
3763 if (_cm->verbose_low()) {
3764 gclog_or_tty->print_cr("[%u] aborting to deal with pending SATB buffers",
3765 _worker_id);
3766 }
3767 // we do need to process SATB buffers, we'll abort and restart
3768 // the marking task to do so
3769 set_has_aborted();
3770 statsOnly( ++_aborted_satb );
3771 return;
3772 }
3773 }
3774
3775 void CMTask::recalculate_limits() {
3776 _real_words_scanned_limit = _words_scanned + words_scanned_period;
3777 _words_scanned_limit = _real_words_scanned_limit;
3778
3779 _real_refs_reached_limit = _refs_reached + refs_reached_period;
3780 _refs_reached_limit = _real_refs_reached_limit;
3781 }
3782
3783 void CMTask::decrease_limits() {
3784 // This is called when we believe that we're going to do an infrequent
3785 // operation which will increase the per byte scanned cost (i.e. move
3786 // entries to/from the global stack). It basically tries to decrease the
3787 // scanning limit so that the clock is called earlier.
3788
3789 if (_cm->verbose_medium()) {
3790 gclog_or_tty->print_cr("[%u] decreasing limits", _worker_id);
3791 }
3792
3793 _words_scanned_limit = _real_words_scanned_limit -
3794 3 * words_scanned_period / 4;
3795 _refs_reached_limit = _real_refs_reached_limit -
3796 3 * refs_reached_period / 4;
3797 }
3798
3799 void CMTask::move_entries_to_global_stack() {
3800 // local array where we'll store the entries that will be popped
3801 // from the local queue
3802 oop buffer[global_stack_transfer_size];
3803
3804 int n = 0;
3805 oop obj;
3806 while (n < global_stack_transfer_size && _task_queue->pop_local(obj)) {
3807 buffer[n] = obj;
3808 ++n;
3809 }
3810
3811 if (n > 0) {
3812 // we popped at least one entry from the local queue
3813
3814 statsOnly( ++_global_transfers_to; _local_pops += n );
3815
3816 if (!_cm->mark_stack_push(buffer, n)) {
3817 if (_cm->verbose_low()) {
3818 gclog_or_tty->print_cr("[%u] aborting due to global stack overflow",
3819 _worker_id);
3820 }
3821 set_has_aborted();
3822 } else {
3823 // the transfer was successful
3824
3825 if (_cm->verbose_medium()) {
3826 gclog_or_tty->print_cr("[%u] pushed %d entries to the global stack",
3827 _worker_id, n);
3828 }
3829 statsOnly( int tmp_size = _cm->mark_stack_size();
3830 if (tmp_size > _global_max_size) {
3831 _global_max_size = tmp_size;
3832 }
3833 _global_pushes += n );
3834 }
3835 }
3836
3837 // this operation was quite expensive, so decrease the limits
3838 decrease_limits();
3839 }
3840
3841 void CMTask::get_entries_from_global_stack() {
3842 // local array where we'll store the entries that will be popped
3843 // from the global stack.
3844 oop buffer[global_stack_transfer_size];
3845 int n;
3846 _cm->mark_stack_pop(buffer, global_stack_transfer_size, &n);
3847 assert(n <= global_stack_transfer_size,
3848 "we should not pop more than the given limit");
3849 if (n > 0) {
3850 // yes, we did actually pop at least one entry
3851
3852 statsOnly( ++_global_transfers_from; _global_pops += n );
3853 if (_cm->verbose_medium()) {
3854 gclog_or_tty->print_cr("[%u] popped %d entries from the global stack",
3855 _worker_id, n);
3856 }
3857 for (int i = 0; i < n; ++i) {
3858 bool success = _task_queue->push(buffer[i]);
3859 // We only call this when the local queue is empty or under a
3860 // given target limit. So, we do not expect this push to fail.
3861 assert(success, "invariant");
3862 }
3863
3864 statsOnly( int tmp_size = _task_queue->size();
3865 if (tmp_size > _local_max_size) {
3866 _local_max_size = tmp_size;
3867 }
3868 _local_pushes += n );
3869 }
3870
3871 // this operation was quite expensive, so decrease the limits
3872 decrease_limits();
3873 }
3874
3875 void CMTask::drain_local_queue(bool partially) {
3876 if (has_aborted()) return;
3877
3878 // Decide what the target size is, depending whether we're going to
3879 // drain it partially (so that other tasks can steal if they run out
3880 // of things to do) or totally (at the very end).
3881 size_t target_size;
3882 if (partially) {
3883 target_size = MIN2((size_t)_task_queue->max_elems()/3, GCDrainStackTargetSize);
3884 } else {
3885 target_size = 0;
3886 }
3887
3888 if (_task_queue->size() > target_size) {
3889 if (_cm->verbose_high()) {
3890 gclog_or_tty->print_cr("[%u] draining local queue, target size = " SIZE_FORMAT,
3891 _worker_id, target_size);
3892 }
3893
3894 oop obj;
3895 bool ret = _task_queue->pop_local(obj);
3896 while (ret) {
3897 statsOnly( ++_local_pops );
3898
3899 if (_cm->verbose_high()) {
3900 gclog_or_tty->print_cr("[%u] popped "PTR_FORMAT, _worker_id,
3901 p2i((void*) obj));
3902 }
3903
3904 assert(_g1h->is_in_g1_reserved((HeapWord*) obj), "invariant" );
3905 assert(!_g1h->is_on_master_free_list(
3906 _g1h->heap_region_containing((HeapWord*) obj)), "invariant");
3907
3908 scan_object(obj);
3909
3910 if (_task_queue->size() <= target_size || has_aborted()) {
3911 ret = false;
3912 } else {
3913 ret = _task_queue->pop_local(obj);
3914 }
3915 }
3916
3917 if (_cm->verbose_high()) {
3918 gclog_or_tty->print_cr("[%u] drained local queue, size = %u",
3919 _worker_id, _task_queue->size());
3920 }
3921 }
3922 }
3923
3924 void CMTask::drain_global_stack(bool partially) {
3925 if (has_aborted()) return;
3926
3927 // We have a policy to drain the local queue before we attempt to
3928 // drain the global stack.
3929 assert(partially || _task_queue->size() == 0, "invariant");
3930
3931 // Decide what the target size is, depending whether we're going to
3932 // drain it partially (so that other tasks can steal if they run out
3933 // of things to do) or totally (at the very end). Notice that,
3934 // because we move entries from the global stack in chunks or
3935 // because another task might be doing the same, we might in fact
3936 // drop below the target. But, this is not a problem.
3937 size_t target_size;
3938 if (partially) {
3939 target_size = _cm->partial_mark_stack_size_target();
3940 } else {
3941 target_size = 0;
3942 }
3943
3944 if (_cm->mark_stack_size() > target_size) {
3945 if (_cm->verbose_low()) {
3946 gclog_or_tty->print_cr("[%u] draining global_stack, target size " SIZE_FORMAT,
3947 _worker_id, target_size);
3948 }
3949
3950 while (!has_aborted() && _cm->mark_stack_size() > target_size) {
3951 get_entries_from_global_stack();
3952 drain_local_queue(partially);
3953 }
3954
3955 if (_cm->verbose_low()) {
3956 gclog_or_tty->print_cr("[%u] drained global stack, size = " SIZE_FORMAT,
3957 _worker_id, _cm->mark_stack_size());
3958 }
3959 }
3960 }
3961
3962 // SATB Queue has several assumptions on whether to call the par or
3963 // non-par versions of the methods. this is why some of the code is
3964 // replicated. We should really get rid of the single-threaded version
3965 // of the code to simplify things.
3966 void CMTask::drain_satb_buffers() {
3967 if (has_aborted()) return;
3968
3969 // We set this so that the regular clock knows that we're in the
3970 // middle of draining buffers and doesn't set the abort flag when it
3971 // notices that SATB buffers are available for draining. It'd be
3972 // very counter productive if it did that. :-)
3973 _draining_satb_buffers = true;
3974
3975 CMObjectClosure oc(this);
3976 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
3977 if (G1CollectedHeap::use_parallel_gc_threads()) {
3978 satb_mq_set.set_par_closure(_worker_id, &oc);
3979 } else {
3980 satb_mq_set.set_closure(&oc);
3981 }
3982
3983 // This keeps claiming and applying the closure to completed buffers
3984 // until we run out of buffers or we need to abort.
3985 if (G1CollectedHeap::use_parallel_gc_threads()) {
3986 while (!has_aborted() &&
3987 satb_mq_set.par_apply_closure_to_completed_buffer(_worker_id)) {
3988 if (_cm->verbose_medium()) {
3989 gclog_or_tty->print_cr("[%u] processed an SATB buffer", _worker_id);
3990 }
3991 statsOnly( ++_satb_buffers_processed );
3992 regular_clock_call();
3993 }
3994 } else {
3995 while (!has_aborted() &&
3996 satb_mq_set.apply_closure_to_completed_buffer()) {
3997 if (_cm->verbose_medium()) {
3998 gclog_or_tty->print_cr("[%u] processed an SATB buffer", _worker_id);
3999 }
4000 statsOnly( ++_satb_buffers_processed );
4001 regular_clock_call();
4002 }
4003 }
4004
4005 _draining_satb_buffers = false;
4006
4007 assert(has_aborted() ||
4008 concurrent() ||
4009 satb_mq_set.completed_buffers_num() == 0, "invariant");
4010
4011 if (G1CollectedHeap::use_parallel_gc_threads()) {
4012 satb_mq_set.set_par_closure(_worker_id, NULL);
4013 } else {
4014 satb_mq_set.set_closure(NULL);
4015 }
4016
4017 // again, this was a potentially expensive operation, decrease the
4018 // limits to get the regular clock call early
4019 decrease_limits();
4020 }
4021
4022 void CMTask::print_stats() {
4023 gclog_or_tty->print_cr("Marking Stats, task = %u, calls = %d",
4024 _worker_id, _calls);
4025 gclog_or_tty->print_cr(" Elapsed time = %1.2lfms, Termination time = %1.2lfms",
4026 _elapsed_time_ms, _termination_time_ms);
4027 gclog_or_tty->print_cr(" Step Times (cum): num = %d, avg = %1.2lfms, sd = %1.2lfms",
4028 _step_times_ms.num(), _step_times_ms.avg(),
4029 _step_times_ms.sd());
4030 gclog_or_tty->print_cr(" max = %1.2lfms, total = %1.2lfms",
4031 _step_times_ms.maximum(), _step_times_ms.sum());
4032
4033 #if _MARKING_STATS_
4034 gclog_or_tty->print_cr(" Clock Intervals (cum): num = %d, avg = %1.2lfms, sd = %1.2lfms",
4035 _all_clock_intervals_ms.num(), _all_clock_intervals_ms.avg(),
4036 _all_clock_intervals_ms.sd());
4037 gclog_or_tty->print_cr(" max = %1.2lfms, total = %1.2lfms",
4038 _all_clock_intervals_ms.maximum(),
4039 _all_clock_intervals_ms.sum());
4040 gclog_or_tty->print_cr(" Clock Causes (cum): scanning = %d, marking = %d",
4041 _clock_due_to_scanning, _clock_due_to_marking);
4042 gclog_or_tty->print_cr(" Objects: scanned = %d, found on the bitmap = %d",
4043 _objs_scanned, _objs_found_on_bitmap);
4044 gclog_or_tty->print_cr(" Local Queue: pushes = %d, pops = %d, max size = %d",
4045 _local_pushes, _local_pops, _local_max_size);
4046 gclog_or_tty->print_cr(" Global Stack: pushes = %d, pops = %d, max size = %d",
4047 _global_pushes, _global_pops, _global_max_size);
4048 gclog_or_tty->print_cr(" transfers to = %d, transfers from = %d",
4049 _global_transfers_to,_global_transfers_from);
4050 gclog_or_tty->print_cr(" Regions: claimed = %d", _regions_claimed);
4051 gclog_or_tty->print_cr(" SATB buffers: processed = %d", _satb_buffers_processed);
4052 gclog_or_tty->print_cr(" Steals: attempts = %d, successes = %d",
4053 _steal_attempts, _steals);
4054 gclog_or_tty->print_cr(" Aborted: %d, due to", _aborted);
4055 gclog_or_tty->print_cr(" overflow: %d, global abort: %d, yield: %d",
4056 _aborted_overflow, _aborted_cm_aborted, _aborted_yield);
4057 gclog_or_tty->print_cr(" time out: %d, SATB: %d, termination: %d",
4058 _aborted_timed_out, _aborted_satb, _aborted_termination);
4059 #endif // _MARKING_STATS_
4060 }
4061
4062 /*****************************************************************************
4063
4064 The do_marking_step(time_target_ms, ...) method is the building
4065 block of the parallel marking framework. It can be called in parallel
4066 with other invocations of do_marking_step() on different tasks
4067 (but only one per task, obviously) and concurrently with the
4068 mutator threads, or during remark, hence it eliminates the need
4069 for two versions of the code. When called during remark, it will
4070 pick up from where the task left off during the concurrent marking
4071 phase. Interestingly, tasks are also claimable during evacuation
4072 pauses too, since do_marking_step() ensures that it aborts before
4073 it needs to yield.
4074
4075 The data structures that it uses to do marking work are the
4076 following:
4077
4078 (1) Marking Bitmap. If there are gray objects that appear only
4079 on the bitmap (this happens either when dealing with an overflow
4080 or when the initial marking phase has simply marked the roots
4081 and didn't push them on the stack), then tasks claim heap
4082 regions whose bitmap they then scan to find gray objects. A
4083 global finger indicates where the end of the last claimed region
4084 is. A local finger indicates how far into the region a task has
4085 scanned. The two fingers are used to determine how to gray an
4086 object (i.e. whether simply marking it is OK, as it will be
4087 visited by a task in the future, or whether it needs to be also
4088 pushed on a stack).
4089
4090 (2) Local Queue. The local queue of the task which is accessed
4091 reasonably efficiently by the task. Other tasks can steal from
4092 it when they run out of work. Throughout the marking phase, a
4093 task attempts to keep its local queue short but not totally
4094 empty, so that entries are available for stealing by other
4095 tasks. Only when there is no more work, a task will totally
4096 drain its local queue.
4097
4098 (3) Global Mark Stack. This handles local queue overflow. During
4099 marking only sets of entries are moved between it and the local
4100 queues, as access to it requires a mutex and more fine-grain
4101 interaction with it which might cause contention. If it
4102 overflows, then the marking phase should restart and iterate
4103 over the bitmap to identify gray objects. Throughout the marking
4104 phase, tasks attempt to keep the global mark stack at a small
4105 length but not totally empty, so that entries are available for
4106 popping by other tasks. Only when there is no more work, tasks
4107 will totally drain the global mark stack.
4108
4109 (4) SATB Buffer Queue. This is where completed SATB buffers are
4110 made available. Buffers are regularly removed from this queue
4111 and scanned for roots, so that the queue doesn't get too
4112 long. During remark, all completed buffers are processed, as
4113 well as the filled in parts of any uncompleted buffers.
4114
4115 The do_marking_step() method tries to abort when the time target
4116 has been reached. There are a few other cases when the
4117 do_marking_step() method also aborts:
4118
4119 (1) When the marking phase has been aborted (after a Full GC).
4120
4121 (2) When a global overflow (on the global stack) has been
4122 triggered. Before the task aborts, it will actually sync up with
4123 the other tasks to ensure that all the marking data structures
4124 (local queues, stacks, fingers etc.) are re-initialized so that
4125 when do_marking_step() completes, the marking phase can
4126 immediately restart.
4127
4128 (3) When enough completed SATB buffers are available. The
4129 do_marking_step() method only tries to drain SATB buffers right
4130 at the beginning. So, if enough buffers are available, the
4131 marking step aborts and the SATB buffers are processed at
4132 the beginning of the next invocation.
4133
4134 (4) To yield. when we have to yield then we abort and yield
4135 right at the end of do_marking_step(). This saves us from a lot
4136 of hassle as, by yielding we might allow a Full GC. If this
4137 happens then objects will be compacted underneath our feet, the
4138 heap might shrink, etc. We save checking for this by just
4139 aborting and doing the yield right at the end.
4140
4141 From the above it follows that the do_marking_step() method should
4142 be called in a loop (or, otherwise, regularly) until it completes.
4143
4144 If a marking step completes without its has_aborted() flag being
4145 true, it means it has completed the current marking phase (and
4146 also all other marking tasks have done so and have all synced up).
4147
4148 A method called regular_clock_call() is invoked "regularly" (in
4149 sub ms intervals) throughout marking. It is this clock method that
4150 checks all the abort conditions which were mentioned above and
4151 decides when the task should abort. A work-based scheme is used to
4152 trigger this clock method: when the number of object words the
4153 marking phase has scanned or the number of references the marking
4154 phase has visited reach a given limit. Additional invocations to
4155 the method clock have been planted in a few other strategic places
4156 too. The initial reason for the clock method was to avoid calling
4157 vtime too regularly, as it is quite expensive. So, once it was in
4158 place, it was natural to piggy-back all the other conditions on it
4159 too and not constantly check them throughout the code.
4160
4161 If do_termination is true then do_marking_step will enter its
4162 termination protocol.
4163
4164 The value of is_serial must be true when do_marking_step is being
4165 called serially (i.e. by the VMThread) and do_marking_step should
4166 skip any synchronization in the termination and overflow code.
4167 Examples include the serial remark code and the serial reference
4168 processing closures.
4169
4170 The value of is_serial must be false when do_marking_step is
4171 being called by any of the worker threads in a work gang.
4172 Examples include the concurrent marking code (CMMarkingTask),
4173 the MT remark code, and the MT reference processing closures.
4174
4175 *****************************************************************************/
4176
4177 void CMTask::do_marking_step(double time_target_ms,
4178 bool do_termination,
4179 bool is_serial) {
4180 assert(time_target_ms >= 1.0, "minimum granularity is 1ms");
4181 assert(concurrent() == _cm->concurrent(), "they should be the same");
4182
4183 G1CollectorPolicy* g1_policy = _g1h->g1_policy();
4184 assert(_task_queues != NULL, "invariant");
4185 assert(_task_queue != NULL, "invariant");
4186 assert(_task_queues->queue(_worker_id) == _task_queue, "invariant");
4187
4188 assert(!_claimed,
4189 "only one thread should claim this task at any one time");
4190
4191 // OK, this doesn't safeguard again all possible scenarios, as it is
4192 // possible for two threads to set the _claimed flag at the same
4193 // time. But it is only for debugging purposes anyway and it will
4194 // catch most problems.
4195 _claimed = true;
4196
4197 _start_time_ms = os::elapsedVTime() * 1000.0;
4198 statsOnly( _interval_start_time_ms = _start_time_ms );
4199
4200 // If do_stealing is true then do_marking_step will attempt to
4201 // steal work from the other CMTasks. It only makes sense to
4202 // enable stealing when the termination protocol is enabled
4203 // and do_marking_step() is not being called serially.
4204 bool do_stealing = do_termination && !is_serial;
4205
4206 double diff_prediction_ms =
4207 g1_policy->get_new_prediction(&_marking_step_diffs_ms);
4208 _time_target_ms = time_target_ms - diff_prediction_ms;
4209
4210 // set up the variables that are used in the work-based scheme to
4211 // call the regular clock method
4212 _words_scanned = 0;
4213 _refs_reached = 0;
4214 recalculate_limits();
4215
4216 // clear all flags
4217 clear_has_aborted();
4218 _has_timed_out = false;
4219 _draining_satb_buffers = false;
4220
4221 ++_calls;
4222
4223 if (_cm->verbose_low()) {
4224 gclog_or_tty->print_cr("[%u] >>>>>>>>>> START, call = %d, "
4225 "target = %1.2lfms >>>>>>>>>>",
4226 _worker_id, _calls, _time_target_ms);
4227 }
4228
4229 // Set up the bitmap and oop closures. Anything that uses them is
4230 // eventually called from this method, so it is OK to allocate these
4231 // statically.
4232 CMBitMapClosure bitmap_closure(this, _cm, _nextMarkBitMap);
4233 G1CMOopClosure cm_oop_closure(_g1h, _cm, this);
4234 set_cm_oop_closure(&cm_oop_closure);
4235
4236 if (_cm->has_overflown()) {
4237 // This can happen if the mark stack overflows during a GC pause
4238 // and this task, after a yield point, restarts. We have to abort
4239 // as we need to get into the overflow protocol which happens
4240 // right at the end of this task.
4241 set_has_aborted();
4242 }
4243
4244 // First drain any available SATB buffers. After this, we will not
4245 // look at SATB buffers before the next invocation of this method.
4246 // If enough completed SATB buffers are queued up, the regular clock
4247 // will abort this task so that it restarts.
4248 drain_satb_buffers();
4249 // ...then partially drain the local queue and the global stack
4250 drain_local_queue(true);
4251 drain_global_stack(true);
4252
4253 do {
4254 if (!has_aborted() && _curr_region != NULL) {
4255 // This means that we're already holding on to a region.
4256 assert(_finger != NULL, "if region is not NULL, then the finger "
4257 "should not be NULL either");
4258
4259 // We might have restarted this task after an evacuation pause
4260 // which might have evacuated the region we're holding on to
4261 // underneath our feet. Let's read its limit again to make sure
4262 // that we do not iterate over a region of the heap that
4263 // contains garbage (update_region_limit() will also move
4264 // _finger to the start of the region if it is found empty).
4265 update_region_limit();
4266 // We will start from _finger not from the start of the region,
4267 // as we might be restarting this task after aborting half-way
4268 // through scanning this region. In this case, _finger points to
4269 // the address where we last found a marked object. If this is a
4270 // fresh region, _finger points to start().
4271 MemRegion mr = MemRegion(_finger, _region_limit);
4272
4273 if (_cm->verbose_low()) {
4274 gclog_or_tty->print_cr("[%u] we're scanning part "
4275 "["PTR_FORMAT", "PTR_FORMAT") "
4276 "of region "HR_FORMAT,
4277 _worker_id, p2i(_finger), p2i(_region_limit),
4278 HR_FORMAT_PARAMS(_curr_region));
4279 }
4280
4281 assert(!_curr_region->isHumongous() || mr.start() == _curr_region->bottom(),
4282 "humongous regions should go around loop once only");
4283
4284 // Some special cases:
4285 // If the memory region is empty, we can just give up the region.
4286 // If the current region is humongous then we only need to check
4287 // the bitmap for the bit associated with the start of the object,
4288 // scan the object if it's live, and give up the region.
4289 // Otherwise, let's iterate over the bitmap of the part of the region
4290 // that is left.
4291 // If the iteration is successful, give up the region.
4292 if (mr.is_empty()) {
4293 giveup_current_region();
4294 regular_clock_call();
4295 } else if (_curr_region->isHumongous() && mr.start() == _curr_region->bottom()) {
4296 if (_nextMarkBitMap->isMarked(mr.start())) {
4297 // The object is marked - apply the closure
4298 BitMap::idx_t offset = _nextMarkBitMap->heapWordToOffset(mr.start());
4299 bitmap_closure.do_bit(offset);
4300 }
4301 // Even if this task aborted while scanning the humongous object
4302 // we can (and should) give up the current region.
4303 giveup_current_region();
4304 regular_clock_call();
4305 } else if (_nextMarkBitMap->iterate(&bitmap_closure, mr)) {
4306 giveup_current_region();
4307 regular_clock_call();
4308 } else {
4309 assert(has_aborted(), "currently the only way to do so");
4310 // The only way to abort the bitmap iteration is to return
4311 // false from the do_bit() method. However, inside the
4312 // do_bit() method we move the _finger to point to the
4313 // object currently being looked at. So, if we bail out, we
4314 // have definitely set _finger to something non-null.
4315 assert(_finger != NULL, "invariant");
4316
4317 // Region iteration was actually aborted. So now _finger
4318 // points to the address of the object we last scanned. If we
4319 // leave it there, when we restart this task, we will rescan
4320 // the object. It is easy to avoid this. We move the finger by
4321 // enough to point to the next possible object header (the
4322 // bitmap knows by how much we need to move it as it knows its
4323 // granularity).
4324 assert(_finger < _region_limit, "invariant");
4325 HeapWord* new_finger = _nextMarkBitMap->nextObject(_finger);
4326 // Check if bitmap iteration was aborted while scanning the last object
4327 if (new_finger >= _region_limit) {
4328 giveup_current_region();
4329 } else {
4330 move_finger_to(new_finger);
4331 }
4332 }
4333 }
4334 // At this point we have either completed iterating over the
4335 // region we were holding on to, or we have aborted.
4336
4337 // We then partially drain the local queue and the global stack.
4338 // (Do we really need this?)
4339 drain_local_queue(true);
4340 drain_global_stack(true);
4341
4342 // Read the note on the claim_region() method on why it might
4343 // return NULL with potentially more regions available for
4344 // claiming and why we have to check out_of_regions() to determine
4345 // whether we're done or not.
4346 while (!has_aborted() && _curr_region == NULL && !_cm->out_of_regions()) {
4347 // We are going to try to claim a new region. We should have
4348 // given up on the previous one.
4349 // Separated the asserts so that we know which one fires.
4350 assert(_curr_region == NULL, "invariant");
4351 assert(_finger == NULL, "invariant");
4352 assert(_region_limit == NULL, "invariant");
4353 if (_cm->verbose_low()) {
4354 gclog_or_tty->print_cr("[%u] trying to claim a new region", _worker_id);
4355 }
4356 HeapRegion* claimed_region = _cm->claim_region(_worker_id);
4357 if (claimed_region != NULL) {
4358 // Yes, we managed to claim one
4359 statsOnly( ++_regions_claimed );
4360
4361 if (_cm->verbose_low()) {
4362 gclog_or_tty->print_cr("[%u] we successfully claimed "
4363 "region "PTR_FORMAT,
4364 _worker_id, p2i(claimed_region));
4365 }
4366
4367 setup_for_region(claimed_region);
4368 assert(_curr_region == claimed_region, "invariant");
4369 }
4370 // It is important to call the regular clock here. It might take
4371 // a while to claim a region if, for example, we hit a large
4372 // block of empty regions. So we need to call the regular clock
4373 // method once round the loop to make sure it's called
4374 // frequently enough.
4375 regular_clock_call();
4376 }
4377
4378 if (!has_aborted() && _curr_region == NULL) {
4379 assert(_cm->out_of_regions(),
4380 "at this point we should be out of regions");
4381 }
4382 } while ( _curr_region != NULL && !has_aborted());
4383
4384 if (!has_aborted()) {
4385 // We cannot check whether the global stack is empty, since other
4386 // tasks might be pushing objects to it concurrently.
4387 assert(_cm->out_of_regions(),
4388 "at this point we should be out of regions");
4389
4390 if (_cm->verbose_low()) {
4391 gclog_or_tty->print_cr("[%u] all regions claimed", _worker_id);
4392 }
4393
4394 // Try to reduce the number of available SATB buffers so that
4395 // remark has less work to do.
4396 drain_satb_buffers();
4397 }
4398
4399 // Since we've done everything else, we can now totally drain the
4400 // local queue and global stack.
4401 drain_local_queue(false);
4402 drain_global_stack(false);
4403
4404 // Attempt at work stealing from other task's queues.
4405 if (do_stealing && !has_aborted()) {
4406 // We have not aborted. This means that we have finished all that
4407 // we could. Let's try to do some stealing...
4408
4409 // We cannot check whether the global stack is empty, since other
4410 // tasks might be pushing objects to it concurrently.
4411 assert(_cm->out_of_regions() && _task_queue->size() == 0,
4412 "only way to reach here");
4413
4414 if (_cm->verbose_low()) {
4415 gclog_or_tty->print_cr("[%u] starting to steal", _worker_id);
4416 }
4417
4418 while (!has_aborted()) {
4419 oop obj;
4420 statsOnly( ++_steal_attempts );
4421
4422 if (_cm->try_stealing(_worker_id, &_hash_seed, obj)) {
4423 if (_cm->verbose_medium()) {
4424 gclog_or_tty->print_cr("[%u] stolen "PTR_FORMAT" successfully",
4425 _worker_id, p2i((void*) obj));
4426 }
4427
4428 statsOnly( ++_steals );
4429
4430 assert(_nextMarkBitMap->isMarked((HeapWord*) obj),
4431 "any stolen object should be marked");
4432 scan_object(obj);
4433
4434 // And since we're towards the end, let's totally drain the
4435 // local queue and global stack.
4436 drain_local_queue(false);
4437 drain_global_stack(false);
4438 } else {
4439 break;
4440 }
4441 }
4442 }
4443
4444 // If we are about to wrap up and go into termination, check if we
4445 // should raise the overflow flag.
4446 if (do_termination && !has_aborted()) {
4447 if (_cm->force_overflow()->should_force()) {
4448 _cm->set_has_overflown();
4449 regular_clock_call();
4450 }
4451 }
4452
4453 // We still haven't aborted. Now, let's try to get into the
4454 // termination protocol.
4455 if (do_termination && !has_aborted()) {
4456 // We cannot check whether the global stack is empty, since other
4457 // tasks might be concurrently pushing objects on it.
4458 // Separated the asserts so that we know which one fires.
4459 assert(_cm->out_of_regions(), "only way to reach here");
4460 assert(_task_queue->size() == 0, "only way to reach here");
4461
4462 if (_cm->verbose_low()) {
4463 gclog_or_tty->print_cr("[%u] starting termination protocol", _worker_id);
4464 }
4465
4466 _termination_start_time_ms = os::elapsedVTime() * 1000.0;
4467
4468 // The CMTask class also extends the TerminatorTerminator class,
4469 // hence its should_exit_termination() method will also decide
4470 // whether to exit the termination protocol or not.
4471 bool finished = (is_serial ||
4472 _cm->terminator()->offer_termination(this));
4473 double termination_end_time_ms = os::elapsedVTime() * 1000.0;
4474 _termination_time_ms +=
4475 termination_end_time_ms - _termination_start_time_ms;
4476
4477 if (finished) {
4478 // We're all done.
4479
4480 if (_worker_id == 0) {
4481 // let's allow task 0 to do this
4482 if (concurrent()) {
4483 assert(_cm->concurrent_marking_in_progress(), "invariant");
4484 // we need to set this to false before the next
4485 // safepoint. This way we ensure that the marking phase
4486 // doesn't observe any more heap expansions.
4487 _cm->clear_concurrent_marking_in_progress();
4488 }
4489 }
4490
4491 // We can now guarantee that the global stack is empty, since
4492 // all other tasks have finished. We separated the guarantees so
4493 // that, if a condition is false, we can immediately find out
4494 // which one.
4495 guarantee(_cm->out_of_regions(), "only way to reach here");
4496 guarantee(_cm->mark_stack_empty(), "only way to reach here");
4497 guarantee(_task_queue->size() == 0, "only way to reach here");
4498 guarantee(!_cm->has_overflown(), "only way to reach here");
4499 guarantee(!_cm->mark_stack_overflow(), "only way to reach here");
4500
4501 if (_cm->verbose_low()) {
4502 gclog_or_tty->print_cr("[%u] all tasks terminated", _worker_id);
4503 }
4504 } else {
4505 // Apparently there's more work to do. Let's abort this task. It
4506 // will restart it and we can hopefully find more things to do.
4507
4508 if (_cm->verbose_low()) {
4509 gclog_or_tty->print_cr("[%u] apparently there is more work to do",
4510 _worker_id);
4511 }
4512
4513 set_has_aborted();
4514 statsOnly( ++_aborted_termination );
4515 }
4516 }
4517
4518 // Mainly for debugging purposes to make sure that a pointer to the
4519 // closure which was statically allocated in this frame doesn't
4520 // escape it by accident.
4521 set_cm_oop_closure(NULL);
4522 double end_time_ms = os::elapsedVTime() * 1000.0;
4523 double elapsed_time_ms = end_time_ms - _start_time_ms;
4524 // Update the step history.
4525 _step_times_ms.add(elapsed_time_ms);
4526
4527 if (has_aborted()) {
4528 // The task was aborted for some reason.
4529
4530 statsOnly( ++_aborted );
4531
4532 if (_has_timed_out) {
4533 double diff_ms = elapsed_time_ms - _time_target_ms;
4534 // Keep statistics of how well we did with respect to hitting
4535 // our target only if we actually timed out (if we aborted for
4536 // other reasons, then the results might get skewed).
4537 _marking_step_diffs_ms.add(diff_ms);
4538 }
4539
4540 if (_cm->has_overflown()) {
4541 // This is the interesting one. We aborted because a global
4542 // overflow was raised. This means we have to restart the
4543 // marking phase and start iterating over regions. However, in
4544 // order to do this we have to make sure that all tasks stop
4545 // what they are doing and re-initialize in a safe manner. We
4546 // will achieve this with the use of two barrier sync points.
4547
4548 if (_cm->verbose_low()) {
4549 gclog_or_tty->print_cr("[%u] detected overflow", _worker_id);
4550 }
4551
4552 if (!is_serial) {
4553 // We only need to enter the sync barrier if being called
4554 // from a parallel context
4555 _cm->enter_first_sync_barrier(_worker_id);
4556
4557 // When we exit this sync barrier we know that all tasks have
4558 // stopped doing marking work. So, it's now safe to
4559 // re-initialize our data structures. At the end of this method,
4560 // task 0 will clear the global data structures.
4561 }
4562
4563 statsOnly( ++_aborted_overflow );
4564
4565 // We clear the local state of this task...
4566 clear_region_fields();
4567
4568 if (!is_serial) {
4569 // ...and enter the second barrier.
4570 _cm->enter_second_sync_barrier(_worker_id);
4571 }
4572 // At this point, if we're during the concurrent phase of
4573 // marking, everything has been re-initialized and we're
4574 // ready to restart.
4575 }
4576
4577 if (_cm->verbose_low()) {
4578 gclog_or_tty->print_cr("[%u] <<<<<<<<<< ABORTING, target = %1.2lfms, "
4579 "elapsed = %1.2lfms <<<<<<<<<<",
4580 _worker_id, _time_target_ms, elapsed_time_ms);
4581 if (_cm->has_aborted()) {
4582 gclog_or_tty->print_cr("[%u] ========== MARKING ABORTED ==========",
4583 _worker_id);
4584 }
4585 }
4586 } else {
4587 if (_cm->verbose_low()) {
4588 gclog_or_tty->print_cr("[%u] <<<<<<<<<< FINISHED, target = %1.2lfms, "
4589 "elapsed = %1.2lfms <<<<<<<<<<",
4590 _worker_id, _time_target_ms, elapsed_time_ms);
4591 }
4592 }
4593
4594 _claimed = false;
4595 }
4596
4597 CMTask::CMTask(uint worker_id,
4598 ConcurrentMark* cm,
4599 size_t* marked_bytes,
4600 BitMap* card_bm,
4601 CMTaskQueue* task_queue,
4602 CMTaskQueueSet* task_queues)
4603 : _g1h(G1CollectedHeap::heap()),
4604 _worker_id(worker_id), _cm(cm),
4605 _claimed(false),
4606 _nextMarkBitMap(NULL), _hash_seed(17),
4607 _task_queue(task_queue),
4608 _task_queues(task_queues),
4609 _cm_oop_closure(NULL),
4610 _marked_bytes_array(marked_bytes),
4611 _card_bm(card_bm) {
4612 guarantee(task_queue != NULL, "invariant");
4613 guarantee(task_queues != NULL, "invariant");
4614
4615 statsOnly( _clock_due_to_scanning = 0;
4616 _clock_due_to_marking = 0 );
4617
4618 _marking_step_diffs_ms.add(0.5);
4619 }
4620
4621 // These are formatting macros that are used below to ensure
4622 // consistent formatting. The *_H_* versions are used to format the
4623 // header for a particular value and they should be kept consistent
4624 // with the corresponding macro. Also note that most of the macros add
4625 // the necessary white space (as a prefix) which makes them a bit
4626 // easier to compose.
4627
4628 // All the output lines are prefixed with this string to be able to
4629 // identify them easily in a large log file.
4630 #define G1PPRL_LINE_PREFIX "###"
4631
4632 #define G1PPRL_ADDR_BASE_FORMAT " "PTR_FORMAT"-"PTR_FORMAT
4633 #ifdef _LP64
4634 #define G1PPRL_ADDR_BASE_H_FORMAT " %37s"
4635 #else // _LP64
4636 #define G1PPRL_ADDR_BASE_H_FORMAT " %21s"
4637 #endif // _LP64
4638
4639 // For per-region info
4640 #define G1PPRL_TYPE_FORMAT " %-4s"
4641 #define G1PPRL_TYPE_H_FORMAT " %4s"
4642 #define G1PPRL_BYTE_FORMAT " "SIZE_FORMAT_W(9)
4643 #define G1PPRL_BYTE_H_FORMAT " %9s"
4644 #define G1PPRL_DOUBLE_FORMAT " %14.1f"
4645 #define G1PPRL_DOUBLE_H_FORMAT " %14s"
4646
4647 // For summary info
4648 #define G1PPRL_SUM_ADDR_FORMAT(tag) " "tag":"G1PPRL_ADDR_BASE_FORMAT
4649 #define G1PPRL_SUM_BYTE_FORMAT(tag) " "tag": "SIZE_FORMAT
4650 #define G1PPRL_SUM_MB_FORMAT(tag) " "tag": %1.2f MB"
4651 #define G1PPRL_SUM_MB_PERC_FORMAT(tag) G1PPRL_SUM_MB_FORMAT(tag)" / %1.2f %%"
4652
4653 G1PrintRegionLivenessInfoClosure::
4654 G1PrintRegionLivenessInfoClosure(outputStream* out, const char* phase_name)
4655 : _out(out),
4656 _total_used_bytes(0), _total_capacity_bytes(0),
4657 _total_prev_live_bytes(0), _total_next_live_bytes(0),
4658 _hum_used_bytes(0), _hum_capacity_bytes(0),
4659 _hum_prev_live_bytes(0), _hum_next_live_bytes(0),
4660 _total_remset_bytes(0), _total_strong_code_roots_bytes(0) {
4661 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4662 MemRegion g1_reserved = g1h->g1_reserved();
4663 double now = os::elapsedTime();
4664
4665 // Print the header of the output.
4666 _out->cr();
4667 _out->print_cr(G1PPRL_LINE_PREFIX" PHASE %s @ %1.3f", phase_name, now);
4668 _out->print_cr(G1PPRL_LINE_PREFIX" HEAP"
4669 G1PPRL_SUM_ADDR_FORMAT("reserved")
4670 G1PPRL_SUM_BYTE_FORMAT("region-size"),
4671 p2i(g1_reserved.start()), p2i(g1_reserved.end()),
4672 HeapRegion::GrainBytes);
4673 _out->print_cr(G1PPRL_LINE_PREFIX);
4674 _out->print_cr(G1PPRL_LINE_PREFIX
4675 G1PPRL_TYPE_H_FORMAT
4676 G1PPRL_ADDR_BASE_H_FORMAT
4677 G1PPRL_BYTE_H_FORMAT
4678 G1PPRL_BYTE_H_FORMAT
4679 G1PPRL_BYTE_H_FORMAT
4680 G1PPRL_DOUBLE_H_FORMAT
4681 G1PPRL_BYTE_H_FORMAT
4682 G1PPRL_BYTE_H_FORMAT,
4683 "type", "address-range",
4684 "used", "prev-live", "next-live", "gc-eff",
4685 "remset", "code-roots");
4686 _out->print_cr(G1PPRL_LINE_PREFIX
4687 G1PPRL_TYPE_H_FORMAT
4688 G1PPRL_ADDR_BASE_H_FORMAT
4689 G1PPRL_BYTE_H_FORMAT
4690 G1PPRL_BYTE_H_FORMAT
4691 G1PPRL_BYTE_H_FORMAT
4692 G1PPRL_DOUBLE_H_FORMAT
4693 G1PPRL_BYTE_H_FORMAT
4694 G1PPRL_BYTE_H_FORMAT,
4695 "", "",
4696 "(bytes)", "(bytes)", "(bytes)", "(bytes/ms)",
4697 "(bytes)", "(bytes)");
4698 }
4699
4700 // It takes as a parameter a reference to one of the _hum_* fields, it
4701 // deduces the corresponding value for a region in a humongous region
4702 // series (either the region size, or what's left if the _hum_* field
4703 // is < the region size), and updates the _hum_* field accordingly.
4704 size_t G1PrintRegionLivenessInfoClosure::get_hum_bytes(size_t* hum_bytes) {
4705 size_t bytes = 0;
4706 // The > 0 check is to deal with the prev and next live bytes which
4707 // could be 0.
4708 if (*hum_bytes > 0) {
4709 bytes = MIN2(HeapRegion::GrainBytes, *hum_bytes);
4710 *hum_bytes -= bytes;
4711 }
4712 return bytes;
4713 }
4714
4715 // It deduces the values for a region in a humongous region series
4716 // from the _hum_* fields and updates those accordingly. It assumes
4717 // that that _hum_* fields have already been set up from the "starts
4718 // humongous" region and we visit the regions in address order.
4719 void G1PrintRegionLivenessInfoClosure::get_hum_bytes(size_t* used_bytes,
4720 size_t* capacity_bytes,
4721 size_t* prev_live_bytes,
4722 size_t* next_live_bytes) {
4723 assert(_hum_used_bytes > 0 && _hum_capacity_bytes > 0, "pre-condition");
4724 *used_bytes = get_hum_bytes(&_hum_used_bytes);
4725 *capacity_bytes = get_hum_bytes(&_hum_capacity_bytes);
4726 *prev_live_bytes = get_hum_bytes(&_hum_prev_live_bytes);
4727 *next_live_bytes = get_hum_bytes(&_hum_next_live_bytes);
4728 }
4729
4730 bool G1PrintRegionLivenessInfoClosure::doHeapRegion(HeapRegion* r) {
4731 const char* type = "";
4732 HeapWord* bottom = r->bottom();
4733 HeapWord* end = r->end();
4734 size_t capacity_bytes = r->capacity();
4735 size_t used_bytes = r->used();
4736 size_t prev_live_bytes = r->live_bytes();
4737 size_t next_live_bytes = r->next_live_bytes();
4738 double gc_eff = r->gc_efficiency();
4739 size_t remset_bytes = r->rem_set()->mem_size();
4740 size_t strong_code_roots_bytes = r->rem_set()->strong_code_roots_mem_size();
4741
4742 if (r->used() == 0) {
4743 type = "FREE";
4744 } else if (r->is_survivor()) {
4745 type = "SURV";
4746 } else if (r->is_young()) {
4747 type = "EDEN";
4748 } else if (r->startsHumongous()) {
4749 type = "HUMS";
4750
4751 assert(_hum_used_bytes == 0 && _hum_capacity_bytes == 0 &&
4752 _hum_prev_live_bytes == 0 && _hum_next_live_bytes == 0,
4753 "they should have been zeroed after the last time we used them");
4754 // Set up the _hum_* fields.
4755 _hum_capacity_bytes = capacity_bytes;
4756 _hum_used_bytes = used_bytes;
4757 _hum_prev_live_bytes = prev_live_bytes;
4758 _hum_next_live_bytes = next_live_bytes;
4759 get_hum_bytes(&used_bytes, &capacity_bytes,
4760 &prev_live_bytes, &next_live_bytes);
4761 end = bottom + HeapRegion::GrainWords;
4762 } else if (r->continuesHumongous()) {
4763 type = "HUMC";
4764 get_hum_bytes(&used_bytes, &capacity_bytes,
4765 &prev_live_bytes, &next_live_bytes);
4766 assert(end == bottom + HeapRegion::GrainWords, "invariant");
4767 } else {
4768 type = "OLD";
4769 }
4770
4771 _total_used_bytes += used_bytes;
4772 _total_capacity_bytes += capacity_bytes;
4773 _total_prev_live_bytes += prev_live_bytes;
4774 _total_next_live_bytes += next_live_bytes;
4775 _total_remset_bytes += remset_bytes;
4776 _total_strong_code_roots_bytes += strong_code_roots_bytes;
4777
4778 // Print a line for this particular region.
4779 _out->print_cr(G1PPRL_LINE_PREFIX
4780 G1PPRL_TYPE_FORMAT
4781 G1PPRL_ADDR_BASE_FORMAT
4782 G1PPRL_BYTE_FORMAT
4783 G1PPRL_BYTE_FORMAT
4784 G1PPRL_BYTE_FORMAT
4785 G1PPRL_DOUBLE_FORMAT
4786 G1PPRL_BYTE_FORMAT
4787 G1PPRL_BYTE_FORMAT,
4788 type, p2i(bottom), p2i(end),
4789 used_bytes, prev_live_bytes, next_live_bytes, gc_eff,
4790 remset_bytes, strong_code_roots_bytes);
4791
4792 return false;
4793 }
4794
4795 G1PrintRegionLivenessInfoClosure::~G1PrintRegionLivenessInfoClosure() {
4796 // add static memory usages to remembered set sizes
4797 _total_remset_bytes += HeapRegionRemSet::fl_mem_size() + HeapRegionRemSet::static_mem_size();
4798 // Print the footer of the output.
4799 _out->print_cr(G1PPRL_LINE_PREFIX);
4800 _out->print_cr(G1PPRL_LINE_PREFIX
4801 " SUMMARY"
4802 G1PPRL_SUM_MB_FORMAT("capacity")
4803 G1PPRL_SUM_MB_PERC_FORMAT("used")
4804 G1PPRL_SUM_MB_PERC_FORMAT("prev-live")
4805 G1PPRL_SUM_MB_PERC_FORMAT("next-live")
4806 G1PPRL_SUM_MB_FORMAT("remset")
4807 G1PPRL_SUM_MB_FORMAT("code-roots"),
4808 bytes_to_mb(_total_capacity_bytes),
4809 bytes_to_mb(_total_used_bytes),
4810 perc(_total_used_bytes, _total_capacity_bytes),
4811 bytes_to_mb(_total_prev_live_bytes),
4812 perc(_total_prev_live_bytes, _total_capacity_bytes),
4813 bytes_to_mb(_total_next_live_bytes),
4814 perc(_total_next_live_bytes, _total_capacity_bytes),
4815 bytes_to_mb(_total_remset_bytes),
4816 bytes_to_mb(_total_strong_code_roots_bytes));
4817 _out->cr();
4818 }