1 /*
2 * Copyright (c) 2001, 2016, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/metadataOnStackMark.hpp"
27 #include "classfile/symbolTable.hpp"
28 #include "code/codeCache.hpp"
29 #include "gc/g1/concurrentMarkThread.inline.hpp"
30 #include "gc/g1/g1CollectedHeap.inline.hpp"
31 #include "gc/g1/g1CollectorPolicy.hpp"
32 #include "gc/g1/g1CollectorState.hpp"
33 #include "gc/g1/g1ConcurrentMark.inline.hpp"
34 #include "gc/g1/g1HeapVerifier.hpp"
35 #include "gc/g1/g1OopClosures.inline.hpp"
36 #include "gc/g1/g1StringDedup.hpp"
37 #include "gc/g1/heapRegion.inline.hpp"
38 #include "gc/g1/heapRegionRemSet.hpp"
39 #include "gc/g1/heapRegionSet.inline.hpp"
40 #include "gc/g1/suspendibleThreadSet.hpp"
41 #include "gc/shared/gcId.hpp"
42 #include "gc/shared/gcTimer.hpp"
43 #include "gc/shared/gcTrace.hpp"
44 #include "gc/shared/gcTraceTime.inline.hpp"
45 #include "gc/shared/genOopClosures.inline.hpp"
46 #include "gc/shared/referencePolicy.hpp"
47 #include "gc/shared/strongRootsScope.hpp"
48 #include "gc/shared/taskqueue.inline.hpp"
49 #include "gc/shared/vmGCOperations.hpp"
50 #include "logging/log.hpp"
51 #include "memory/allocation.hpp"
52 #include "memory/resourceArea.hpp"
53 #include "oops/oop.inline.hpp"
54 #include "runtime/atomic.inline.hpp"
55 #include "runtime/handles.inline.hpp"
56 #include "runtime/java.hpp"
57 #include "runtime/prefetch.inline.hpp"
58 #include "services/memTracker.hpp"
59
60 // Concurrent marking bit map wrapper
61
62 G1CMBitMapRO::G1CMBitMapRO(int shifter) :
63 _bm(),
64 _shifter(shifter) {
65 _bmStartWord = 0;
66 _bmWordSize = 0;
67 }
68
69 HeapWord* G1CMBitMapRO::getNextMarkedWordAddress(const HeapWord* addr,
70 const HeapWord* limit) const {
71 // First we must round addr *up* to a possible object boundary.
72 addr = (HeapWord*)align_size_up((intptr_t)addr,
73 HeapWordSize << _shifter);
74 size_t addrOffset = heapWordToOffset(addr);
75 assert(limit != NULL, "limit must not be NULL");
76 size_t limitOffset = heapWordToOffset(limit);
77 size_t nextOffset = _bm.get_next_one_offset(addrOffset, limitOffset);
78 HeapWord* nextAddr = offsetToHeapWord(nextOffset);
79 assert(nextAddr >= addr, "get_next_one postcondition");
80 assert(nextAddr == limit || isMarked(nextAddr),
81 "get_next_one postcondition");
82 return nextAddr;
83 }
84
85 #ifndef PRODUCT
86 bool G1CMBitMapRO::covers(MemRegion heap_rs) const {
87 // assert(_bm.map() == _virtual_space.low(), "map inconsistency");
88 assert(((size_t)_bm.size() * ((size_t)1 << _shifter)) == _bmWordSize,
89 "size inconsistency");
90 return _bmStartWord == (HeapWord*)(heap_rs.start()) &&
91 _bmWordSize == heap_rs.word_size();
92 }
93 #endif
94
95 void G1CMBitMapRO::print_on_error(outputStream* st, const char* prefix) const {
96 _bm.print_on_error(st, prefix);
97 }
98
99 size_t G1CMBitMap::compute_size(size_t heap_size) {
100 return ReservedSpace::allocation_align_size_up(heap_size / mark_distance());
101 }
102
103 size_t G1CMBitMap::mark_distance() {
104 return MinObjAlignmentInBytes * BitsPerByte;
105 }
106
107 void G1CMBitMap::initialize(MemRegion heap, G1RegionToSpaceMapper* storage) {
108 _bmStartWord = heap.start();
109 _bmWordSize = heap.word_size();
110
111 _bm.set_map((BitMap::bm_word_t*) storage->reserved().start());
112 _bm.set_size(_bmWordSize >> _shifter);
113
114 storage->set_mapping_changed_listener(&_listener);
115 }
116
117 void G1CMBitMapMappingChangedListener::on_commit(uint start_region, size_t num_regions, bool zero_filled) {
118 if (zero_filled) {
119 return;
120 }
121 // We need to clear the bitmap on commit, removing any existing information.
122 MemRegion mr(G1CollectedHeap::heap()->bottom_addr_for_region(start_region), num_regions * HeapRegion::GrainWords);
123 _bm->clearRange(mr);
124 }
125
126 // Closure used for clearing the given mark bitmap.
127 class ClearBitmapHRClosure : public AbortableHeapRegionClosure {
128 private:
129 G1ConcurrentMark* _cm;
130 G1CMBitMap* _bitmap;
131 bool _may_yield; // The closure may yield during iteration. If yielded, abort the iteration.
132 public:
133 ClearBitmapHRClosure(G1ConcurrentMark* cm, G1CMBitMap* bitmap, bool may_yield) : AbortableHeapRegionClosure(), _cm(cm), _bitmap(bitmap), _may_yield(may_yield) {
134 assert(!may_yield || cm != NULL, "CM must be non-NULL if this closure is expected to yield.");
135 }
136
137 virtual bool doHeapRegionAbortable(HeapRegion* r) {
138 size_t const chunk_size_in_words = M / HeapWordSize;
139
140 HeapWord* cur = r->bottom();
141 HeapWord* const end = r->end();
142
143 while (cur < end) {
144 MemRegion mr(cur, MIN2(cur + chunk_size_in_words, end));
145 _bitmap->clearRange(mr);
146
147 cur += chunk_size_in_words;
148
149 // Abort iteration if after yielding the marking has been aborted.
150 if (_may_yield && _cm->do_yield_check() && _cm->has_aborted()) {
151 return true;
152 }
153 // Repeat the asserts from before the start of the closure. We will do them
154 // as asserts here to minimize their overhead on the product. However, we
155 // will have them as guarantees at the beginning / end of the bitmap
156 // clearing to get some checking in the product.
157 assert(!_may_yield || _cm->cmThread()->during_cycle(), "invariant");
158 assert(!_may_yield || !G1CollectedHeap::heap()->collector_state()->mark_in_progress(), "invariant");
159 }
160
161 return false;
162 }
163 };
164
165 class ParClearNextMarkBitmapTask : public AbstractGangTask {
166 ClearBitmapHRClosure* _cl;
167 HeapRegionClaimer _hrclaimer;
168 bool _suspendible; // If the task is suspendible, workers must join the STS.
169
170 public:
171 ParClearNextMarkBitmapTask(ClearBitmapHRClosure *cl, uint n_workers, bool suspendible) :
172 _cl(cl), _suspendible(suspendible), AbstractGangTask("Parallel Clear Bitmap Task"), _hrclaimer(n_workers) {}
173
174 void work(uint worker_id) {
175 SuspendibleThreadSetJoiner sts_join(_suspendible);
176 G1CollectedHeap::heap()->heap_region_par_iterate(_cl, worker_id, &_hrclaimer, true);
177 }
178 };
179
180 void G1CMBitMap::clearAll() {
181 G1CollectedHeap* g1h = G1CollectedHeap::heap();
182 ClearBitmapHRClosure cl(NULL, this, false /* may_yield */);
183 uint n_workers = g1h->workers()->active_workers();
184 ParClearNextMarkBitmapTask task(&cl, n_workers, false);
185 g1h->workers()->run_task(&task);
186 guarantee(cl.complete(), "Must have completed iteration.");
187 return;
188 }
189
190 void G1CMBitMap::clearRange(MemRegion mr) {
191 mr.intersection(MemRegion(_bmStartWord, _bmWordSize));
192 assert(!mr.is_empty(), "unexpected empty region");
193 // convert address range into offset range
194 _bm.at_put_range(heapWordToOffset(mr.start()),
195 heapWordToOffset(mr.end()), false);
196 }
197
198 G1CMMarkStack::G1CMMarkStack(G1ConcurrentMark* cm) :
199 _base(NULL), _cm(cm)
200 {}
201
202 bool G1CMMarkStack::allocate(size_t capacity) {
203 // allocate a stack of the requisite depth
204 ReservedSpace rs(ReservedSpace::allocation_align_size_up(capacity * sizeof(oop)));
205 if (!rs.is_reserved()) {
206 warning("ConcurrentMark MarkStack allocation failure");
207 return false;
208 }
209 MemTracker::record_virtual_memory_type((address)rs.base(), mtGC);
210 if (!_virtual_space.initialize(rs, rs.size())) {
211 warning("ConcurrentMark MarkStack backing store failure");
212 // Release the virtual memory reserved for the marking stack
213 rs.release();
214 return false;
215 }
216 assert(_virtual_space.committed_size() == rs.size(),
217 "Didn't reserve backing store for all of G1ConcurrentMark stack?");
218 _base = (oop*) _virtual_space.low();
219 setEmpty();
220 _capacity = (jint) capacity;
221 _saved_index = -1;
222 _should_expand = false;
223 return true;
224 }
225
226 void G1CMMarkStack::expand() {
227 // Called, during remark, if we've overflown the marking stack during marking.
228 assert(isEmpty(), "stack should been emptied while handling overflow");
229 assert(_capacity <= (jint) MarkStackSizeMax, "stack bigger than permitted");
230 // Clear expansion flag
231 _should_expand = false;
232 if (_capacity == (jint) MarkStackSizeMax) {
233 log_trace(gc)("(benign) Can't expand marking stack capacity, at max size limit");
234 return;
235 }
236 // Double capacity if possible
237 jint new_capacity = MIN2(_capacity*2, (jint) MarkStackSizeMax);
238 // Do not give up existing stack until we have managed to
239 // get the double capacity that we desired.
240 ReservedSpace rs(ReservedSpace::allocation_align_size_up(new_capacity *
241 sizeof(oop)));
242 if (rs.is_reserved()) {
243 // Release the backing store associated with old stack
244 _virtual_space.release();
245 // Reinitialize virtual space for new stack
246 if (!_virtual_space.initialize(rs, rs.size())) {
247 fatal("Not enough swap for expanded marking stack capacity");
248 }
249 _base = (oop*)(_virtual_space.low());
250 _index = 0;
251 _capacity = new_capacity;
252 } else {
253 // Failed to double capacity, continue;
254 log_trace(gc)("(benign) Failed to expand marking stack capacity from " SIZE_FORMAT "K to " SIZE_FORMAT "K",
255 _capacity / K, new_capacity / K);
256 }
257 }
258
259 void G1CMMarkStack::set_should_expand() {
260 // If we're resetting the marking state because of an
261 // marking stack overflow, record that we should, if
262 // possible, expand the stack.
263 _should_expand = _cm->has_overflown();
264 }
265
266 G1CMMarkStack::~G1CMMarkStack() {
267 if (_base != NULL) {
268 _base = NULL;
269 _virtual_space.release();
270 }
271 }
272
273 void G1CMMarkStack::par_push_arr(oop* ptr_arr, int n) {
274 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
275 jint start = _index;
276 jint next_index = start + n;
277 if (next_index > _capacity) {
278 _overflow = true;
279 return;
280 }
281 // Otherwise.
282 _index = next_index;
283 for (int i = 0; i < n; i++) {
284 int ind = start + i;
285 assert(ind < _capacity, "By overflow test above.");
286 _base[ind] = ptr_arr[i];
287 }
288 }
289
290 bool G1CMMarkStack::par_pop_arr(oop* ptr_arr, int max, int* n) {
291 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
292 jint index = _index;
293 if (index == 0) {
294 *n = 0;
295 return false;
296 } else {
297 int k = MIN2(max, index);
298 jint new_ind = index - k;
299 for (int j = 0; j < k; j++) {
300 ptr_arr[j] = _base[new_ind + j];
301 }
302 _index = new_ind;
303 *n = k;
304 return true;
305 }
306 }
307
308 void G1CMMarkStack::note_start_of_gc() {
309 assert(_saved_index == -1,
310 "note_start_of_gc()/end_of_gc() bracketed incorrectly");
311 _saved_index = _index;
312 }
313
314 void G1CMMarkStack::note_end_of_gc() {
315 // This is intentionally a guarantee, instead of an assert. If we
316 // accidentally add something to the mark stack during GC, it
317 // will be a correctness issue so it's better if we crash. we'll
318 // only check this once per GC anyway, so it won't be a performance
319 // issue in any way.
320 guarantee(_saved_index == _index,
321 "saved index: %d index: %d", _saved_index, _index);
322 _saved_index = -1;
323 }
324
325 G1CMRootRegions::G1CMRootRegions() :
326 _young_list(NULL), _cm(NULL), _scan_in_progress(false),
327 _should_abort(false), _next_survivor(NULL) { }
328
329 void G1CMRootRegions::init(G1CollectedHeap* g1h, G1ConcurrentMark* cm) {
330 _young_list = g1h->young_list();
331 _cm = cm;
332 }
333
334 void G1CMRootRegions::prepare_for_scan() {
335 assert(!scan_in_progress(), "pre-condition");
336
337 // Currently, only survivors can be root regions.
338 assert(_next_survivor == NULL, "pre-condition");
339 _next_survivor = _young_list->first_survivor_region();
340 _scan_in_progress = (_next_survivor != NULL);
341 _should_abort = false;
342 }
343
344 HeapRegion* G1CMRootRegions::claim_next() {
345 if (_should_abort) {
346 // If someone has set the should_abort flag, we return NULL to
347 // force the caller to bail out of their loop.
348 return NULL;
349 }
350
351 // Currently, only survivors can be root regions.
352 HeapRegion* res = _next_survivor;
353 if (res != NULL) {
354 MutexLockerEx x(RootRegionScan_lock, Mutex::_no_safepoint_check_flag);
355 // Read it again in case it changed while we were waiting for the lock.
356 res = _next_survivor;
357 if (res != NULL) {
358 if (res == _young_list->last_survivor_region()) {
359 // We just claimed the last survivor so store NULL to indicate
360 // that we're done.
361 _next_survivor = NULL;
362 } else {
363 _next_survivor = res->get_next_young_region();
364 }
365 } else {
366 // Someone else claimed the last survivor while we were trying
367 // to take the lock so nothing else to do.
368 }
369 }
370 assert(res == NULL || res->is_survivor(), "post-condition");
371
372 return res;
373 }
374
375 void G1CMRootRegions::notify_scan_done() {
376 MutexLockerEx x(RootRegionScan_lock, Mutex::_no_safepoint_check_flag);
377 _scan_in_progress = false;
378 RootRegionScan_lock->notify_all();
379 }
380
381 void G1CMRootRegions::cancel_scan() {
382 notify_scan_done();
383 }
384
385 void G1CMRootRegions::scan_finished() {
386 assert(scan_in_progress(), "pre-condition");
387
388 // Currently, only survivors can be root regions.
389 if (!_should_abort) {
390 assert(_next_survivor == NULL, "we should have claimed all survivors");
391 }
392 _next_survivor = NULL;
393
394 notify_scan_done();
395 }
396
397 bool G1CMRootRegions::wait_until_scan_finished() {
398 if (!scan_in_progress()) return false;
399
400 {
401 MutexLockerEx x(RootRegionScan_lock, Mutex::_no_safepoint_check_flag);
402 while (scan_in_progress()) {
403 RootRegionScan_lock->wait(Mutex::_no_safepoint_check_flag);
404 }
405 }
406 return true;
407 }
408
409 uint G1ConcurrentMark::scale_parallel_threads(uint n_par_threads) {
410 return MAX2((n_par_threads + 2) / 4, 1U);
411 }
412
413 G1ConcurrentMark::G1ConcurrentMark(G1CollectedHeap* g1h, G1RegionToSpaceMapper* prev_bitmap_storage, G1RegionToSpaceMapper* next_bitmap_storage) :
414 _g1h(g1h),
415 _markBitMap1(),
416 _markBitMap2(),
417 _parallel_marking_threads(0),
418 _max_parallel_marking_threads(0),
419 _sleep_factor(0.0),
420 _marking_task_overhead(1.0),
421 _cleanup_list("Cleanup List"),
422 _region_bm((BitMap::idx_t)(g1h->max_regions()), false /* in_resource_area*/),
423 _card_bm((g1h->reserved_region().byte_size() + CardTableModRefBS::card_size - 1) >>
424 CardTableModRefBS::card_shift,
425 false /* in_resource_area*/),
426
427 _prevMarkBitMap(&_markBitMap1),
428 _nextMarkBitMap(&_markBitMap2),
429
430 _markStack(this),
431 // _finger set in set_non_marking_state
432
433 _max_worker_id(ParallelGCThreads),
434 // _active_tasks set in set_non_marking_state
435 // _tasks set inside the constructor
436 _task_queues(new G1CMTaskQueueSet((int) _max_worker_id)),
437 _terminator(ParallelTaskTerminator((int) _max_worker_id, _task_queues)),
438
439 _has_overflown(false),
440 _concurrent(false),
441 _has_aborted(false),
442 _restart_for_overflow(false),
443 _concurrent_marking_in_progress(false),
444 _concurrent_phase_status(ConcPhaseNotStarted),
445
446 // _verbose_level set below
447
448 _init_times(),
449 _remark_times(), _remark_mark_times(), _remark_weak_ref_times(),
450 _cleanup_times(),
451 _total_counting_time(0.0),
452 _total_rs_scrub_time(0.0),
453
454 _parallel_workers(NULL),
455
456 _count_card_bitmaps(NULL),
457 _count_marked_bytes(NULL),
458 _completed_initialization(false) {
459
460 _markBitMap1.initialize(g1h->reserved_region(), prev_bitmap_storage);
461 _markBitMap2.initialize(g1h->reserved_region(), next_bitmap_storage);
462
463 // Create & start a ConcurrentMark thread.
464 _cmThread = new ConcurrentMarkThread(this);
465 assert(cmThread() != NULL, "CM Thread should have been created");
466 assert(cmThread()->cm() != NULL, "CM Thread should refer to this cm");
467 if (_cmThread->osthread() == NULL) {
468 vm_shutdown_during_initialization("Could not create ConcurrentMarkThread");
469 }
470
471 assert(CGC_lock != NULL, "Where's the CGC_lock?");
472 assert(_markBitMap1.covers(g1h->reserved_region()), "_markBitMap1 inconsistency");
473 assert(_markBitMap2.covers(g1h->reserved_region()), "_markBitMap2 inconsistency");
474
475 SATBMarkQueueSet& satb_qs = JavaThread::satb_mark_queue_set();
476 satb_qs.set_buffer_size(G1SATBBufferSize);
477
478 _root_regions.init(_g1h, this);
479
480 if (ConcGCThreads > ParallelGCThreads) {
481 warning("Can't have more ConcGCThreads (%u) "
482 "than ParallelGCThreads (%u).",
483 ConcGCThreads, ParallelGCThreads);
484 return;
485 }
486 if (!FLAG_IS_DEFAULT(ConcGCThreads) && ConcGCThreads > 0) {
487 // Note: ConcGCThreads has precedence over G1MarkingOverheadPercent
488 // if both are set
489 _sleep_factor = 0.0;
490 _marking_task_overhead = 1.0;
491 } else if (G1MarkingOverheadPercent > 0) {
492 // We will calculate the number of parallel marking threads based
493 // on a target overhead with respect to the soft real-time goal
494 double marking_overhead = (double) G1MarkingOverheadPercent / 100.0;
495 double overall_cm_overhead =
496 (double) MaxGCPauseMillis * marking_overhead /
497 (double) GCPauseIntervalMillis;
498 double cpu_ratio = 1.0 / (double) os::processor_count();
499 double marking_thread_num = ceil(overall_cm_overhead / cpu_ratio);
500 double marking_task_overhead =
501 overall_cm_overhead / marking_thread_num *
502 (double) os::processor_count();
503 double sleep_factor =
504 (1.0 - marking_task_overhead) / marking_task_overhead;
505
506 FLAG_SET_ERGO(uint, ConcGCThreads, (uint) marking_thread_num);
507 _sleep_factor = sleep_factor;
508 _marking_task_overhead = marking_task_overhead;
509 } else {
510 // Calculate the number of parallel marking threads by scaling
511 // the number of parallel GC threads.
512 uint marking_thread_num = scale_parallel_threads(ParallelGCThreads);
513 FLAG_SET_ERGO(uint, ConcGCThreads, marking_thread_num);
514 _sleep_factor = 0.0;
515 _marking_task_overhead = 1.0;
516 }
517
518 assert(ConcGCThreads > 0, "Should have been set");
519 _parallel_marking_threads = ConcGCThreads;
520 _max_parallel_marking_threads = _parallel_marking_threads;
521
522 _parallel_workers = new WorkGang("G1 Marker",
523 _max_parallel_marking_threads, false, true);
524 if (_parallel_workers == NULL) {
525 vm_exit_during_initialization("Failed necessary allocation.");
526 } else {
527 _parallel_workers->initialize_workers();
528 }
529
530 if (FLAG_IS_DEFAULT(MarkStackSize)) {
531 size_t mark_stack_size =
532 MIN2(MarkStackSizeMax,
533 MAX2(MarkStackSize, (size_t) (parallel_marking_threads() * TASKQUEUE_SIZE)));
534 // Verify that the calculated value for MarkStackSize is in range.
535 // It would be nice to use the private utility routine from Arguments.
536 if (!(mark_stack_size >= 1 && mark_stack_size <= MarkStackSizeMax)) {
537 warning("Invalid value calculated for MarkStackSize (" SIZE_FORMAT "): "
538 "must be between 1 and " SIZE_FORMAT,
539 mark_stack_size, MarkStackSizeMax);
540 return;
541 }
542 FLAG_SET_ERGO(size_t, MarkStackSize, mark_stack_size);
543 } else {
544 // Verify MarkStackSize is in range.
545 if (FLAG_IS_CMDLINE(MarkStackSize)) {
546 if (FLAG_IS_DEFAULT(MarkStackSizeMax)) {
547 if (!(MarkStackSize >= 1 && MarkStackSize <= MarkStackSizeMax)) {
548 warning("Invalid value specified for MarkStackSize (" SIZE_FORMAT "): "
549 "must be between 1 and " SIZE_FORMAT,
550 MarkStackSize, MarkStackSizeMax);
551 return;
552 }
553 } else if (FLAG_IS_CMDLINE(MarkStackSizeMax)) {
554 if (!(MarkStackSize >= 1 && MarkStackSize <= MarkStackSizeMax)) {
555 warning("Invalid value specified for MarkStackSize (" SIZE_FORMAT ")"
556 " or for MarkStackSizeMax (" SIZE_FORMAT ")",
557 MarkStackSize, MarkStackSizeMax);
558 return;
559 }
560 }
561 }
562 }
563
564 if (!_markStack.allocate(MarkStackSize)) {
565 warning("Failed to allocate CM marking stack");
566 return;
567 }
568
569 _tasks = NEW_C_HEAP_ARRAY(G1CMTask*, _max_worker_id, mtGC);
570 _accum_task_vtime = NEW_C_HEAP_ARRAY(double, _max_worker_id, mtGC);
571
572 _count_card_bitmaps = NEW_C_HEAP_ARRAY(BitMap, _max_worker_id, mtGC);
573 _count_marked_bytes = NEW_C_HEAP_ARRAY(size_t*, _max_worker_id, mtGC);
574
575 BitMap::idx_t card_bm_size = _card_bm.size();
576
577 // so that the assertion in MarkingTaskQueue::task_queue doesn't fail
578 _active_tasks = _max_worker_id;
579
580 uint max_regions = _g1h->max_regions();
581 for (uint i = 0; i < _max_worker_id; ++i) {
582 G1CMTaskQueue* task_queue = new G1CMTaskQueue();
583 task_queue->initialize();
584 _task_queues->register_queue(i, task_queue);
585
586 _count_card_bitmaps[i] = BitMap(card_bm_size, false);
587 _count_marked_bytes[i] = NEW_C_HEAP_ARRAY(size_t, max_regions, mtGC);
588
589 _tasks[i] = new G1CMTask(i, this,
590 _count_marked_bytes[i],
591 &_count_card_bitmaps[i],
592 task_queue, _task_queues);
593
594 _accum_task_vtime[i] = 0.0;
595 }
596
597 // Calculate the card number for the bottom of the heap. Used
598 // in biasing indexes into the accounting card bitmaps.
599 _heap_bottom_card_num =
600 intptr_t(uintptr_t(_g1h->reserved_region().start()) >>
601 CardTableModRefBS::card_shift);
602
603 // Clear all the liveness counting data
604 clear_all_count_data();
605
606 // so that the call below can read a sensible value
607 _heap_start = g1h->reserved_region().start();
608 set_non_marking_state();
609 _completed_initialization = true;
610 }
611
612 void G1ConcurrentMark::reset() {
613 // Starting values for these two. This should be called in a STW
614 // phase.
615 MemRegion reserved = _g1h->g1_reserved();
616 _heap_start = reserved.start();
617 _heap_end = reserved.end();
618
619 // Separated the asserts so that we know which one fires.
620 assert(_heap_start != NULL, "heap bounds should look ok");
621 assert(_heap_end != NULL, "heap bounds should look ok");
622 assert(_heap_start < _heap_end, "heap bounds should look ok");
623
624 // Reset all the marking data structures and any necessary flags
625 reset_marking_state();
626
627 // We do reset all of them, since different phases will use
628 // different number of active threads. So, it's easiest to have all
629 // of them ready.
630 for (uint i = 0; i < _max_worker_id; ++i) {
631 _tasks[i]->reset(_nextMarkBitMap);
632 }
633
634 // we need this to make sure that the flag is on during the evac
635 // pause with initial mark piggy-backed
636 set_concurrent_marking_in_progress();
637 }
638
639
640 void G1ConcurrentMark::reset_marking_state(bool clear_overflow) {
641 _markStack.set_should_expand();
642 _markStack.setEmpty(); // Also clears the _markStack overflow flag
643 if (clear_overflow) {
644 clear_has_overflown();
645 } else {
646 assert(has_overflown(), "pre-condition");
647 }
648 _finger = _heap_start;
649
650 for (uint i = 0; i < _max_worker_id; ++i) {
651 G1CMTaskQueue* queue = _task_queues->queue(i);
652 queue->set_empty();
653 }
654 }
655
656 void G1ConcurrentMark::set_concurrency(uint active_tasks) {
657 assert(active_tasks <= _max_worker_id, "we should not have more");
658
659 _active_tasks = active_tasks;
660 // Need to update the three data structures below according to the
661 // number of active threads for this phase.
662 _terminator = ParallelTaskTerminator((int) active_tasks, _task_queues);
663 _first_overflow_barrier_sync.set_n_workers((int) active_tasks);
664 _second_overflow_barrier_sync.set_n_workers((int) active_tasks);
665 }
666
667 void G1ConcurrentMark::set_concurrency_and_phase(uint active_tasks, bool concurrent) {
668 set_concurrency(active_tasks);
669
670 _concurrent = concurrent;
671 // We propagate this to all tasks, not just the active ones.
672 for (uint i = 0; i < _max_worker_id; ++i)
673 _tasks[i]->set_concurrent(concurrent);
674
675 if (concurrent) {
676 set_concurrent_marking_in_progress();
677 } else {
678 // We currently assume that the concurrent flag has been set to
679 // false before we start remark. At this point we should also be
680 // in a STW phase.
681 assert(!concurrent_marking_in_progress(), "invariant");
682 assert(out_of_regions(),
683 "only way to get here: _finger: " PTR_FORMAT ", _heap_end: " PTR_FORMAT,
684 p2i(_finger), p2i(_heap_end));
685 }
686 }
687
688 void G1ConcurrentMark::set_non_marking_state() {
689 // We set the global marking state to some default values when we're
690 // not doing marking.
691 reset_marking_state();
692 _active_tasks = 0;
693 clear_concurrent_marking_in_progress();
694 }
695
696 G1ConcurrentMark::~G1ConcurrentMark() {
697 // The G1ConcurrentMark instance is never freed.
698 ShouldNotReachHere();
699 }
700
701 void G1ConcurrentMark::clearNextBitmap() {
702 G1CollectedHeap* g1h = G1CollectedHeap::heap();
703
704 // Make sure that the concurrent mark thread looks to still be in
705 // the current cycle.
706 guarantee(cmThread()->during_cycle(), "invariant");
707
708 // We are finishing up the current cycle by clearing the next
709 // marking bitmap and getting it ready for the next cycle. During
710 // this time no other cycle can start. So, let's make sure that this
711 // is the case.
712 guarantee(!g1h->collector_state()->mark_in_progress(), "invariant");
713
714 ClearBitmapHRClosure cl(this, _nextMarkBitMap, true /* may_yield */);
715 ParClearNextMarkBitmapTask task(&cl, parallel_marking_threads(), true);
716 _parallel_workers->run_task(&task);
717
718 // Clear the liveness counting data. If the marking has been aborted, the abort()
719 // call already did that.
720 if (cl.complete()) {
721 clear_all_count_data();
722 }
723
724 // Repeat the asserts from above.
725 guarantee(cmThread()->during_cycle(), "invariant");
726 guarantee(!g1h->collector_state()->mark_in_progress(), "invariant");
727 }
728
729 class CheckBitmapClearHRClosure : public AbortableHeapRegionClosure {
730 G1CMBitMap* _bitmap;
731 bool _error;
732 public:
733 CheckBitmapClearHRClosure(G1CMBitMap* bitmap) : _bitmap(bitmap) {
734 }
735
736 virtual bool doHeapRegionAbortable(HeapRegion* r) {
737 // This closure can be called concurrently to the mutator, so we must make sure
738 // that the result of the getNextMarkedWordAddress() call is compared to the
739 // value passed to it as limit to detect any found bits.
740 // end never changes in G1.
741 HeapWord* end = r->end();
742 return _bitmap->getNextMarkedWordAddress(r->bottom(), end) != end;
743 }
744 };
745
746 bool G1ConcurrentMark::nextMarkBitmapIsClear() {
747 CheckBitmapClearHRClosure cl(_nextMarkBitMap);
748 _g1h->heap_region_iterate(&cl);
749 return cl.complete();
750 }
751
752 class NoteStartOfMarkHRClosure: public HeapRegionClosure {
753 public:
754 void doHeapRegion(HeapRegion* r) {
755 r->note_start_of_marking();
756 }
757 };
758
759 void G1ConcurrentMark::checkpointRootsInitialPre() {
760 G1CollectedHeap* g1h = G1CollectedHeap::heap();
761 G1CollectorPolicy* g1p = g1h->g1_policy();
762
763 _has_aborted = false;
764
765 // Initialize marking structures. This has to be done in a STW phase.
766 reset();
767
768 // For each region note start of marking.
769 NoteStartOfMarkHRClosure startcl;
770 g1h->heap_region_iterate(&startcl);
771 }
772
773
774 void G1ConcurrentMark::checkpointRootsInitialPost() {
775 G1CollectedHeap* g1h = G1CollectedHeap::heap();
776
777 // Start Concurrent Marking weak-reference discovery.
778 ReferenceProcessor* rp = g1h->ref_processor_cm();
779 // enable ("weak") refs discovery
780 rp->enable_discovery();
781 rp->setup_policy(false); // snapshot the soft ref policy to be used in this cycle
782
783 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
784 // This is the start of the marking cycle, we're expected all
785 // threads to have SATB queues with active set to false.
786 satb_mq_set.set_active_all_threads(true, /* new active value */
787 false /* expected_active */);
788
789 _root_regions.prepare_for_scan();
790
791 // update_g1_committed() will be called at the end of an evac pause
792 // when marking is on. So, it's also called at the end of the
793 // initial-mark pause to update the heap end, if the heap expands
794 // during it. No need to call it here.
795 }
796
797 /*
798 * Notice that in the next two methods, we actually leave the STS
799 * during the barrier sync and join it immediately afterwards. If we
800 * do not do this, the following deadlock can occur: one thread could
801 * be in the barrier sync code, waiting for the other thread to also
802 * sync up, whereas another one could be trying to yield, while also
803 * waiting for the other threads to sync up too.
804 *
805 * Note, however, that this code is also used during remark and in
806 * this case we should not attempt to leave / enter the STS, otherwise
807 * we'll either hit an assert (debug / fastdebug) or deadlock
808 * (product). So we should only leave / enter the STS if we are
809 * operating concurrently.
810 *
811 * Because the thread that does the sync barrier has left the STS, it
812 * is possible to be suspended for a Full GC or an evacuation pause
813 * could occur. This is actually safe, since the entering the sync
814 * barrier is one of the last things do_marking_step() does, and it
815 * doesn't manipulate any data structures afterwards.
816 */
817
818 void G1ConcurrentMark::enter_first_sync_barrier(uint worker_id) {
819 bool barrier_aborted;
820 {
821 SuspendibleThreadSetLeaver sts_leave(concurrent());
822 barrier_aborted = !_first_overflow_barrier_sync.enter();
823 }
824
825 // at this point everyone should have synced up and not be doing any
826 // more work
827
828 if (barrier_aborted) {
829 // If the barrier aborted we ignore the overflow condition and
830 // just abort the whole marking phase as quickly as possible.
831 return;
832 }
833
834 // If we're executing the concurrent phase of marking, reset the marking
835 // state; otherwise the marking state is reset after reference processing,
836 // during the remark pause.
837 // If we reset here as a result of an overflow during the remark we will
838 // see assertion failures from any subsequent set_concurrency_and_phase()
839 // calls.
840 if (concurrent()) {
841 // let the task associated with with worker 0 do this
842 if (worker_id == 0) {
843 // task 0 is responsible for clearing the global data structures
844 // We should be here because of an overflow. During STW we should
845 // not clear the overflow flag since we rely on it being true when
846 // we exit this method to abort the pause and restart concurrent
847 // marking.
848 reset_marking_state(true /* clear_overflow */);
849
850 log_info(gc)("Concurrent Mark reset for overflow");
851 }
852 }
853
854 // after this, each task should reset its own data structures then
855 // then go into the second barrier
856 }
857
858 void G1ConcurrentMark::enter_second_sync_barrier(uint worker_id) {
859 SuspendibleThreadSetLeaver sts_leave(concurrent());
860 _second_overflow_barrier_sync.enter();
861
862 // at this point everything should be re-initialized and ready to go
863 }
864
865 class G1CMConcurrentMarkingTask: public AbstractGangTask {
866 private:
867 G1ConcurrentMark* _cm;
868 ConcurrentMarkThread* _cmt;
869
870 public:
871 void work(uint worker_id) {
872 assert(Thread::current()->is_ConcurrentGC_thread(),
873 "this should only be done by a conc GC thread");
874 ResourceMark rm;
875
876 double start_vtime = os::elapsedVTime();
877
878 {
879 SuspendibleThreadSetJoiner sts_join;
880
881 assert(worker_id < _cm->active_tasks(), "invariant");
882 G1CMTask* the_task = _cm->task(worker_id);
883 the_task->record_start_time();
884 if (!_cm->has_aborted()) {
885 do {
886 double start_vtime_sec = os::elapsedVTime();
887 double mark_step_duration_ms = G1ConcMarkStepDurationMillis;
888
889 the_task->do_marking_step(mark_step_duration_ms,
890 true /* do_termination */,
891 false /* is_serial*/);
892
893 double end_vtime_sec = os::elapsedVTime();
894 double elapsed_vtime_sec = end_vtime_sec - start_vtime_sec;
895 _cm->clear_has_overflown();
896
897 _cm->do_yield_check(worker_id);
898
899 jlong sleep_time_ms;
900 if (!_cm->has_aborted() && the_task->has_aborted()) {
901 sleep_time_ms =
902 (jlong) (elapsed_vtime_sec * _cm->sleep_factor() * 1000.0);
903 {
904 SuspendibleThreadSetLeaver sts_leave;
905 os::sleep(Thread::current(), sleep_time_ms, false);
906 }
907 }
908 } while (!_cm->has_aborted() && the_task->has_aborted());
909 }
910 the_task->record_end_time();
911 guarantee(!the_task->has_aborted() || _cm->has_aborted(), "invariant");
912 }
913
914 double end_vtime = os::elapsedVTime();
915 _cm->update_accum_task_vtime(worker_id, end_vtime - start_vtime);
916 }
917
918 G1CMConcurrentMarkingTask(G1ConcurrentMark* cm,
919 ConcurrentMarkThread* cmt) :
920 AbstractGangTask("Concurrent Mark"), _cm(cm), _cmt(cmt) { }
921
922 ~G1CMConcurrentMarkingTask() { }
923 };
924
925 // Calculates the number of active workers for a concurrent
926 // phase.
927 uint G1ConcurrentMark::calc_parallel_marking_threads() {
928 uint n_conc_workers = 0;
929 if (!UseDynamicNumberOfGCThreads ||
930 (!FLAG_IS_DEFAULT(ConcGCThreads) &&
931 !ForceDynamicNumberOfGCThreads)) {
932 n_conc_workers = max_parallel_marking_threads();
933 } else {
934 n_conc_workers =
935 AdaptiveSizePolicy::calc_default_active_workers(
936 max_parallel_marking_threads(),
937 1, /* Minimum workers */
938 parallel_marking_threads(),
939 Threads::number_of_non_daemon_threads());
940 // Don't scale down "n_conc_workers" by scale_parallel_threads() because
941 // that scaling has already gone into "_max_parallel_marking_threads".
942 }
943 assert(n_conc_workers > 0, "Always need at least 1");
944 return n_conc_workers;
945 }
946
947 void G1ConcurrentMark::scanRootRegion(HeapRegion* hr, uint worker_id) {
948 // Currently, only survivors can be root regions.
949 assert(hr->next_top_at_mark_start() == hr->bottom(), "invariant");
950 G1RootRegionScanClosure cl(_g1h, this, worker_id);
951
952 const uintx interval = PrefetchScanIntervalInBytes;
953 HeapWord* curr = hr->bottom();
954 const HeapWord* end = hr->top();
955 while (curr < end) {
956 Prefetch::read(curr, interval);
957 oop obj = oop(curr);
958 int size = obj->oop_iterate_size(&cl);
959 assert(size == obj->size(), "sanity");
960 curr += size;
961 }
962 }
963
964 class G1CMRootRegionScanTask : public AbstractGangTask {
965 private:
966 G1ConcurrentMark* _cm;
967
968 public:
969 G1CMRootRegionScanTask(G1ConcurrentMark* cm) :
970 AbstractGangTask("Root Region Scan"), _cm(cm) { }
971
972 void work(uint worker_id) {
973 assert(Thread::current()->is_ConcurrentGC_thread(),
974 "this should only be done by a conc GC thread");
975
976 G1CMRootRegions* root_regions = _cm->root_regions();
977 HeapRegion* hr = root_regions->claim_next();
978 while (hr != NULL) {
979 _cm->scanRootRegion(hr, worker_id);
980 hr = root_regions->claim_next();
981 }
982 }
983 };
984
985 void G1ConcurrentMark::scanRootRegions() {
986 // scan_in_progress() will have been set to true only if there was
987 // at least one root region to scan. So, if it's false, we
988 // should not attempt to do any further work.
989 if (root_regions()->scan_in_progress()) {
990 assert(!has_aborted(), "Aborting before root region scanning is finished not supported.");
991 GCTraceConcTime(Info, gc) tt("Concurrent Root Region Scan");
992
993 _parallel_marking_threads = calc_parallel_marking_threads();
994 assert(parallel_marking_threads() <= max_parallel_marking_threads(),
995 "Maximum number of marking threads exceeded");
996 uint active_workers = MAX2(1U, parallel_marking_threads());
997
998 G1CMRootRegionScanTask task(this);
999 _parallel_workers->set_active_workers(active_workers);
1000 _parallel_workers->run_task(&task);
1001
1002 // It's possible that has_aborted() is true here without actually
1003 // aborting the survivor scan earlier. This is OK as it's
1004 // mainly used for sanity checking.
1005 root_regions()->scan_finished();
1006 }
1007 }
1008
1009 void G1ConcurrentMark::register_concurrent_phase_start(const char* title) {
1010 uint old_val = 0;
1011 do {
1012 old_val = Atomic::cmpxchg(ConcPhaseStarted, &_concurrent_phase_status, ConcPhaseNotStarted);
1013 } while (old_val != ConcPhaseNotStarted);
1014 _g1h->gc_timer_cm()->register_gc_concurrent_start(title);
1015 }
1016
1017 void G1ConcurrentMark::register_concurrent_phase_end_common(bool end_timer) {
1018 if (_concurrent_phase_status == ConcPhaseNotStarted) {
1019 return;
1020 }
1021
1022 uint old_val = Atomic::cmpxchg(ConcPhaseStopping, &_concurrent_phase_status, ConcPhaseStarted);
1023 if (old_val == ConcPhaseStarted) {
1024 _g1h->gc_timer_cm()->register_gc_concurrent_end();
1025 // If 'end_timer' is true, we came here to end timer which needs concurrent phase ended.
1026 // We need to end it before changing the status to 'ConcPhaseNotStarted' to prevent
1027 // starting a new concurrent phase by 'ConcurrentMarkThread'.
1028 if (end_timer) {
1029 _g1h->gc_timer_cm()->register_gc_end();
1030 }
1031 old_val = Atomic::cmpxchg(ConcPhaseNotStarted, &_concurrent_phase_status, ConcPhaseStopping);
1032 assert(old_val == ConcPhaseStopping, "Should not have changed since we entered this scope.");
1033 } else {
1034 do {
1035 // Let other thread finish changing '_concurrent_phase_status' to 'ConcPhaseNotStarted'.
1036 os::naked_short_sleep(1);
1037 } while (_concurrent_phase_status != ConcPhaseNotStarted);
1038 }
1039 }
1040
1041 void G1ConcurrentMark::register_concurrent_phase_end() {
1042 register_concurrent_phase_end_common(false);
1043 }
1044
1045 void G1ConcurrentMark::register_concurrent_gc_end_and_stop_timer() {
1046 register_concurrent_phase_end_common(true);
1047 }
1048
1049 void G1ConcurrentMark::markFromRoots() {
1050 // we might be tempted to assert that:
1051 // assert(asynch == !SafepointSynchronize::is_at_safepoint(),
1052 // "inconsistent argument?");
1053 // However that wouldn't be right, because it's possible that
1054 // a safepoint is indeed in progress as a younger generation
1055 // stop-the-world GC happens even as we mark in this generation.
1056
1057 _restart_for_overflow = false;
1058
1059 // _g1h has _n_par_threads
1060 _parallel_marking_threads = calc_parallel_marking_threads();
1061 assert(parallel_marking_threads() <= max_parallel_marking_threads(),
1062 "Maximum number of marking threads exceeded");
1063
1064 uint active_workers = MAX2(1U, parallel_marking_threads());
1065 assert(active_workers > 0, "Should have been set");
1066
1067 // Parallel task terminator is set in "set_concurrency_and_phase()"
1068 set_concurrency_and_phase(active_workers, true /* concurrent */);
1069
1070 G1CMConcurrentMarkingTask markingTask(this, cmThread());
1071 _parallel_workers->set_active_workers(active_workers);
1072 _parallel_workers->run_task(&markingTask);
1073 print_stats();
1074 }
1075
1076 void G1ConcurrentMark::checkpointRootsFinal(bool clear_all_soft_refs) {
1077 // world is stopped at this checkpoint
1078 assert(SafepointSynchronize::is_at_safepoint(),
1079 "world should be stopped");
1080
1081 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1082
1083 // If a full collection has happened, we shouldn't do this.
1084 if (has_aborted()) {
1085 g1h->collector_state()->set_mark_in_progress(false); // So bitmap clearing isn't confused
1086 return;
1087 }
1088
1089 SvcGCMarker sgcm(SvcGCMarker::OTHER);
1090
1091 if (VerifyDuringGC) {
1092 HandleMark hm; // handle scope
1093 g1h->prepare_for_verify();
1094 Universe::verify(VerifyOption_G1UsePrevMarking, "During GC (before)");
1095 }
1096 g1h->verifier()->check_bitmaps("Remark Start");
1097
1098 G1CollectorPolicy* g1p = g1h->g1_policy();
1099 g1p->record_concurrent_mark_remark_start();
1100
1101 double start = os::elapsedTime();
1102
1103 checkpointRootsFinalWork();
1104
1105 double mark_work_end = os::elapsedTime();
1106
1107 weakRefsWork(clear_all_soft_refs);
1108
1109 if (has_overflown()) {
1110 // Oops. We overflowed. Restart concurrent marking.
1111 _restart_for_overflow = true;
1112 log_develop_trace(gc)("Remark led to restart for overflow.");
1113
1114 // Verify the heap w.r.t. the previous marking bitmap.
1115 if (VerifyDuringGC) {
1116 HandleMark hm; // handle scope
1117 g1h->prepare_for_verify();
1118 Universe::verify(VerifyOption_G1UsePrevMarking, "During GC (overflow)");
1119 }
1120
1121 // Clear the marking state because we will be restarting
1122 // marking due to overflowing the global mark stack.
1123 reset_marking_state();
1124 } else {
1125 {
1126 GCTraceTime(Debug, gc) trace("Aggregate Data", g1h->gc_timer_cm());
1127
1128 // Aggregate the per-task counting data that we have accumulated
1129 // while marking.
1130 aggregate_count_data();
1131 }
1132
1133 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
1134 // We're done with marking.
1135 // This is the end of the marking cycle, we're expected all
1136 // threads to have SATB queues with active set to true.
1137 satb_mq_set.set_active_all_threads(false, /* new active value */
1138 true /* expected_active */);
1139
1140 if (VerifyDuringGC) {
1141 HandleMark hm; // handle scope
1142 g1h->prepare_for_verify();
1143 Universe::verify(VerifyOption_G1UseNextMarking, "During GC (after)");
1144 }
1145 g1h->verifier()->check_bitmaps("Remark End");
1146 assert(!restart_for_overflow(), "sanity");
1147 // Completely reset the marking state since marking completed
1148 set_non_marking_state();
1149 }
1150
1151 // Expand the marking stack, if we have to and if we can.
1152 if (_markStack.should_expand()) {
1153 _markStack.expand();
1154 }
1155
1156 // Statistics
1157 double now = os::elapsedTime();
1158 _remark_mark_times.add((mark_work_end - start) * 1000.0);
1159 _remark_weak_ref_times.add((now - mark_work_end) * 1000.0);
1160 _remark_times.add((now - start) * 1000.0);
1161
1162 g1p->record_concurrent_mark_remark_end();
1163
1164 G1CMIsAliveClosure is_alive(g1h);
1165 g1h->gc_tracer_cm()->report_object_count_after_gc(&is_alive);
1166 }
1167
1168 // Base class of the closures that finalize and verify the
1169 // liveness counting data.
1170 class G1CMCountDataClosureBase: public HeapRegionClosure {
1171 protected:
1172 G1CollectedHeap* _g1h;
1173 G1ConcurrentMark* _cm;
1174 CardTableModRefBS* _ct_bs;
1175
1176 BitMap* _region_bm;
1177 BitMap* _card_bm;
1178
1179 // Takes a region that's not empty (i.e., it has at least one
1180 // live object in it and sets its corresponding bit on the region
1181 // bitmap to 1.
1182 void set_bit_for_region(HeapRegion* hr) {
1183 BitMap::idx_t index = (BitMap::idx_t) hr->hrm_index();
1184 _region_bm->par_at_put(index, true);
1185 }
1186
1187 public:
1188 G1CMCountDataClosureBase(G1CollectedHeap* g1h,
1189 BitMap* region_bm, BitMap* card_bm):
1190 _g1h(g1h), _cm(g1h->concurrent_mark()),
1191 _ct_bs(barrier_set_cast<CardTableModRefBS>(g1h->barrier_set())),
1192 _region_bm(region_bm), _card_bm(card_bm) { }
1193 };
1194
1195 // Closure that calculates the # live objects per region. Used
1196 // for verification purposes during the cleanup pause.
1197 class CalcLiveObjectsClosure: public G1CMCountDataClosureBase {
1198 G1CMBitMapRO* _bm;
1199 size_t _region_marked_bytes;
1200
1201 public:
1202 CalcLiveObjectsClosure(G1CMBitMapRO *bm, G1CollectedHeap* g1h,
1203 BitMap* region_bm, BitMap* card_bm) :
1204 G1CMCountDataClosureBase(g1h, region_bm, card_bm),
1205 _bm(bm), _region_marked_bytes(0) { }
1206
1207 void doHeapRegion(HeapRegion* hr) {
1208 HeapWord* ntams = hr->next_top_at_mark_start();
1209 HeapWord* start = hr->bottom();
1210
1211 assert(start <= hr->end() && start <= ntams && ntams <= hr->end(),
1212 "Preconditions not met - "
1213 "start: " PTR_FORMAT ", ntams: " PTR_FORMAT ", end: " PTR_FORMAT,
1214 p2i(start), p2i(ntams), p2i(hr->end()));
1215
1216 // Find the first marked object at or after "start".
1217 start = _bm->getNextMarkedWordAddress(start, ntams);
1218
1219 size_t marked_bytes = 0;
1220
1221 while (start < ntams) {
1222 oop obj = oop(start);
1223 int obj_sz = obj->size();
1224 HeapWord* obj_end = start + obj_sz;
1225
1226 BitMap::idx_t start_idx = _cm->card_bitmap_index_for(start);
1227 BitMap::idx_t end_idx = _cm->card_bitmap_index_for(obj_end);
1228
1229 // Note: if we're looking at the last region in heap - obj_end
1230 // could be actually just beyond the end of the heap; end_idx
1231 // will then correspond to a (non-existent) card that is also
1232 // just beyond the heap.
1233 if (_g1h->is_in_g1_reserved(obj_end) && !_ct_bs->is_card_aligned(obj_end)) {
1234 // end of object is not card aligned - increment to cover
1235 // all the cards spanned by the object
1236 end_idx += 1;
1237 }
1238
1239 // Set the bits in the card BM for the cards spanned by this object.
1240 _cm->set_card_bitmap_range(_card_bm, start_idx, end_idx, true /* is_par */);
1241
1242 // Add the size of this object to the number of marked bytes.
1243 marked_bytes += (size_t)obj_sz * HeapWordSize;
1244
1245 // This will happen if we are handling a humongous object that spans
1246 // several heap regions.
1247 if (obj_end > hr->end()) {
1248 break;
1249 }
1250 // Find the next marked object after this one.
1251 start = _bm->getNextMarkedWordAddress(obj_end, ntams);
1252 }
1253
1254 // Mark the allocated-since-marking portion...
1255 HeapWord* top = hr->top();
1256 if (ntams < top) {
1257 BitMap::idx_t start_idx = _cm->card_bitmap_index_for(ntams);
1258 BitMap::idx_t end_idx = _cm->card_bitmap_index_for(top);
1259
1260 // Note: if we're looking at the last region in heap - top
1261 // could be actually just beyond the end of the heap; end_idx
1262 // will then correspond to a (non-existent) card that is also
1263 // just beyond the heap.
1264 if (_g1h->is_in_g1_reserved(top) && !_ct_bs->is_card_aligned(top)) {
1265 // end of object is not card aligned - increment to cover
1266 // all the cards spanned by the object
1267 end_idx += 1;
1268 }
1269 _cm->set_card_bitmap_range(_card_bm, start_idx, end_idx, true /* is_par */);
1270
1271 // This definitely means the region has live objects.
1272 set_bit_for_region(hr);
1273 }
1274
1275 // Update the live region bitmap.
1276 if (marked_bytes > 0) {
1277 set_bit_for_region(hr);
1278 }
1279
1280 // Set the marked bytes for the current region so that
1281 // it can be queried by a calling verification routine
1282 _region_marked_bytes = marked_bytes;
1283 }
1284
1285 size_t region_marked_bytes() const { return _region_marked_bytes; }
1286 };
1287
1288 // Heap region closure used for verifying the counting data
1289 // that was accumulated concurrently and aggregated during
1290 // the remark pause. This closure is applied to the heap
1291 // regions during the STW cleanup pause.
1292
1293 class VerifyLiveObjectDataHRClosure: public HeapRegionClosure {
1294 G1CollectedHeap* _g1h;
1295 G1ConcurrentMark* _cm;
1296 CalcLiveObjectsClosure _calc_cl;
1297 BitMap* _region_bm; // Region BM to be verified
1298 BitMap* _card_bm; // Card BM to be verified
1299
1300 BitMap* _exp_region_bm; // Expected Region BM values
1301 BitMap* _exp_card_bm; // Expected card BM values
1302
1303 int _failures;
1304
1305 public:
1306 VerifyLiveObjectDataHRClosure(G1CollectedHeap* g1h,
1307 BitMap* region_bm,
1308 BitMap* card_bm,
1309 BitMap* exp_region_bm,
1310 BitMap* exp_card_bm) :
1311 _g1h(g1h), _cm(g1h->concurrent_mark()),
1312 _calc_cl(_cm->nextMarkBitMap(), g1h, exp_region_bm, exp_card_bm),
1313 _region_bm(region_bm), _card_bm(card_bm),
1314 _exp_region_bm(exp_region_bm), _exp_card_bm(exp_card_bm),
1315 _failures(0) { }
1316
1317 int failures() const { return _failures; }
1318
1319 void doHeapRegion(HeapRegion* hr) {
1320 int failures = 0;
1321
1322 // Call the CalcLiveObjectsClosure to walk the marking bitmap for
1323 // this region and set the corresponding bits in the expected region
1324 // and card bitmaps.
1325 _calc_cl.doHeapRegion(hr);
1326
1327 // Verify the marked bytes for this region.
1328 size_t exp_marked_bytes = _calc_cl.region_marked_bytes();
1329 size_t act_marked_bytes = hr->next_marked_bytes();
1330
1331 if (exp_marked_bytes > act_marked_bytes) {
1332 if (hr->is_starts_humongous()) {
1333 // For start_humongous regions, the size of the whole object will be
1334 // in exp_marked_bytes.
1335 HeapRegion* region = hr;
1336 int num_regions;
1337 for (num_regions = 0; region != NULL; num_regions++) {
1338 region = _g1h->next_region_in_humongous(region);
1339 }
1340 if ((num_regions-1) * HeapRegion::GrainBytes >= exp_marked_bytes) {
1341 failures += 1;
1342 } else if (num_regions * HeapRegion::GrainBytes < exp_marked_bytes) {
1343 failures += 1;
1344 }
1345 } else {
1346 // We're not OK if expected marked bytes > actual marked bytes. It means
1347 // we have missed accounting some objects during the actual marking.
1348 failures += 1;
1349 }
1350 }
1351
1352 // Verify the bit, for this region, in the actual and expected
1353 // (which was just calculated) region bit maps.
1354 // We're not OK if the bit in the calculated expected region
1355 // bitmap is set and the bit in the actual region bitmap is not.
1356 BitMap::idx_t index = (BitMap::idx_t) hr->hrm_index();
1357
1358 bool expected = _exp_region_bm->at(index);
1359 bool actual = _region_bm->at(index);
1360 if (expected && !actual) {
1361 failures += 1;
1362 }
1363
1364 // Verify that the card bit maps for the cards spanned by the current
1365 // region match. We have an error if we have a set bit in the expected
1366 // bit map and the corresponding bit in the actual bitmap is not set.
1367
1368 BitMap::idx_t start_idx = _cm->card_bitmap_index_for(hr->bottom());
1369 BitMap::idx_t end_idx = _cm->card_bitmap_index_for(hr->top());
1370
1371 for (BitMap::idx_t i = start_idx; i < end_idx; i+=1) {
1372 expected = _exp_card_bm->at(i);
1373 actual = _card_bm->at(i);
1374
1375 if (expected && !actual) {
1376 failures += 1;
1377 }
1378 }
1379
1380 _failures += failures;
1381 }
1382 };
1383
1384 class G1ParVerifyFinalCountTask: public AbstractGangTask {
1385 protected:
1386 G1CollectedHeap* _g1h;
1387 G1ConcurrentMark* _cm;
1388 BitMap* _actual_region_bm;
1389 BitMap* _actual_card_bm;
1390
1391 uint _n_workers;
1392
1393 BitMap* _expected_region_bm;
1394 BitMap* _expected_card_bm;
1395
1396 int _failures;
1397
1398 HeapRegionClaimer _hrclaimer;
1399
1400 public:
1401 G1ParVerifyFinalCountTask(G1CollectedHeap* g1h,
1402 BitMap* region_bm, BitMap* card_bm,
1403 BitMap* expected_region_bm, BitMap* expected_card_bm)
1404 : AbstractGangTask("G1 verify final counting"),
1405 _g1h(g1h), _cm(_g1h->concurrent_mark()),
1406 _actual_region_bm(region_bm), _actual_card_bm(card_bm),
1407 _expected_region_bm(expected_region_bm), _expected_card_bm(expected_card_bm),
1408 _failures(0),
1409 _n_workers(_g1h->workers()->active_workers()), _hrclaimer(_n_workers) {
1410 assert(VerifyDuringGC, "don't call this otherwise");
1411 assert(_expected_card_bm->size() == _actual_card_bm->size(), "sanity");
1412 assert(_expected_region_bm->size() == _actual_region_bm->size(), "sanity");
1413 }
1414
1415 void work(uint worker_id) {
1416 assert(worker_id < _n_workers, "invariant");
1417
1418 VerifyLiveObjectDataHRClosure verify_cl(_g1h,
1419 _actual_region_bm, _actual_card_bm,
1420 _expected_region_bm,
1421 _expected_card_bm);
1422
1423 _g1h->heap_region_par_iterate(&verify_cl, worker_id, &_hrclaimer);
1424
1425 Atomic::add(verify_cl.failures(), &_failures);
1426 }
1427
1428 int failures() const { return _failures; }
1429 };
1430
1431 // Closure that finalizes the liveness counting data.
1432 // Used during the cleanup pause.
1433 // Sets the bits corresponding to the interval [NTAMS, top]
1434 // (which contains the implicitly live objects) in the
1435 // card liveness bitmap. Also sets the bit for each region,
1436 // containing live data, in the region liveness bitmap.
1437
1438 class FinalCountDataUpdateClosure: public G1CMCountDataClosureBase {
1439 public:
1440 FinalCountDataUpdateClosure(G1CollectedHeap* g1h,
1441 BitMap* region_bm,
1442 BitMap* card_bm) :
1443 G1CMCountDataClosureBase(g1h, region_bm, card_bm) { }
1444
1445 void doHeapRegion(HeapRegion* hr) {
1446 HeapWord* ntams = hr->next_top_at_mark_start();
1447 HeapWord* top = hr->top();
1448
1449 assert(hr->bottom() <= ntams && ntams <= hr->end(), "Preconditions.");
1450
1451 // Mark the allocated-since-marking portion...
1452 if (ntams < top) {
1453 // This definitely means the region has live objects.
1454 set_bit_for_region(hr);
1455
1456 // Now set the bits in the card bitmap for [ntams, top)
1457 BitMap::idx_t start_idx = _cm->card_bitmap_index_for(ntams);
1458 BitMap::idx_t end_idx = _cm->card_bitmap_index_for(top);
1459
1460 // Note: if we're looking at the last region in heap - top
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(top) && !_ct_bs->is_card_aligned(top)) {
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 assert(end_idx <= _card_bm->size(),
1471 "oob: end_idx= " SIZE_FORMAT ", bitmap size= " SIZE_FORMAT,
1472 end_idx, _card_bm->size());
1473 assert(start_idx < _card_bm->size(),
1474 "oob: start_idx= " SIZE_FORMAT ", bitmap size= " SIZE_FORMAT,
1475 start_idx, _card_bm->size());
1476
1477 _cm->set_card_bitmap_range(_card_bm, start_idx, end_idx, true /* is_par */);
1478 }
1479
1480 // Set the bit for the region if it contains live data
1481 if (hr->next_marked_bytes() > 0) {
1482 set_bit_for_region(hr);
1483 }
1484 }
1485 };
1486
1487 class G1ParFinalCountTask: public AbstractGangTask {
1488 protected:
1489 G1CollectedHeap* _g1h;
1490 G1ConcurrentMark* _cm;
1491 BitMap* _actual_region_bm;
1492 BitMap* _actual_card_bm;
1493
1494 uint _n_workers;
1495 HeapRegionClaimer _hrclaimer;
1496
1497 public:
1498 G1ParFinalCountTask(G1CollectedHeap* g1h, BitMap* region_bm, BitMap* card_bm)
1499 : AbstractGangTask("G1 final counting"),
1500 _g1h(g1h), _cm(_g1h->concurrent_mark()),
1501 _actual_region_bm(region_bm), _actual_card_bm(card_bm),
1502 _n_workers(_g1h->workers()->active_workers()), _hrclaimer(_n_workers) {
1503 }
1504
1505 void work(uint worker_id) {
1506 assert(worker_id < _n_workers, "invariant");
1507
1508 FinalCountDataUpdateClosure final_update_cl(_g1h,
1509 _actual_region_bm,
1510 _actual_card_bm);
1511
1512 _g1h->heap_region_par_iterate(&final_update_cl, worker_id, &_hrclaimer);
1513 }
1514 };
1515
1516 class G1NoteEndOfConcMarkClosure : public HeapRegionClosure {
1517 G1CollectedHeap* _g1;
1518 size_t _freed_bytes;
1519 FreeRegionList* _local_cleanup_list;
1520 uint _old_regions_removed;
1521 uint _humongous_regions_removed;
1522 HRRSCleanupTask* _hrrs_cleanup_task;
1523
1524 public:
1525 G1NoteEndOfConcMarkClosure(G1CollectedHeap* g1,
1526 FreeRegionList* local_cleanup_list,
1527 HRRSCleanupTask* hrrs_cleanup_task) :
1528 _g1(g1),
1529 _freed_bytes(0),
1530 _local_cleanup_list(local_cleanup_list),
1531 _old_regions_removed(0),
1532 _humongous_regions_removed(0),
1533 _hrrs_cleanup_task(hrrs_cleanup_task) { }
1534
1535 size_t freed_bytes() { return _freed_bytes; }
1536 const uint old_regions_removed() { return _old_regions_removed; }
1537 const uint humongous_regions_removed() { return _humongous_regions_removed; }
1538
1539 void doHeapRegion(HeapRegion *hr) {
1540 if (hr->is_archive()) {
1541 return;
1542 }
1543 // We use a claim value of zero here because all regions
1544 // were claimed with value 1 in the FinalCount task.
1545 _g1->reset_gc_time_stamps(hr);
1546 hr->note_end_of_marking();
1547
1548 if (hr->used() > 0 && hr->max_live_bytes() == 0 && !hr->is_young()) {
1549 _freed_bytes += hr->used();
1550 hr->set_containing_set(NULL);
1551 if (hr->is_humongous()) {
1552 _humongous_regions_removed++;
1553 _g1->free_humongous_region(hr, _local_cleanup_list, true);
1554 } else {
1555 _old_regions_removed++;
1556 _g1->free_region(hr, _local_cleanup_list, true);
1557 }
1558 } else {
1559 hr->rem_set()->do_cleanup_work(_hrrs_cleanup_task);
1560 }
1561 }
1562 };
1563
1564 class G1ParNoteEndTask: public AbstractGangTask {
1565 friend class G1NoteEndOfConcMarkClosure;
1566
1567 protected:
1568 G1CollectedHeap* _g1h;
1569 FreeRegionList* _cleanup_list;
1570 HeapRegionClaimer _hrclaimer;
1571
1572 public:
1573 G1ParNoteEndTask(G1CollectedHeap* g1h, FreeRegionList* cleanup_list, uint n_workers) :
1574 AbstractGangTask("G1 note end"), _g1h(g1h), _cleanup_list(cleanup_list), _hrclaimer(n_workers) {
1575 }
1576
1577 void work(uint worker_id) {
1578 FreeRegionList local_cleanup_list("Local Cleanup List");
1579 HRRSCleanupTask hrrs_cleanup_task;
1580 G1NoteEndOfConcMarkClosure g1_note_end(_g1h, &local_cleanup_list,
1581 &hrrs_cleanup_task);
1582 _g1h->heap_region_par_iterate(&g1_note_end, worker_id, &_hrclaimer);
1583
1584 // Now update the lists
1585 _g1h->remove_from_old_sets(g1_note_end.old_regions_removed(), g1_note_end.humongous_regions_removed());
1586 {
1587 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
1588 _g1h->decrement_summary_bytes(g1_note_end.freed_bytes());
1589
1590 // If we iterate over the global cleanup list at the end of
1591 // cleanup to do this printing we will not guarantee to only
1592 // generate output for the newly-reclaimed regions (the list
1593 // might not be empty at the beginning of cleanup; we might
1594 // still be working on its previous contents). So we do the
1595 // printing here, before we append the new regions to the global
1596 // cleanup list.
1597
1598 G1HRPrinter* hr_printer = _g1h->hr_printer();
1599 if (hr_printer->is_active()) {
1600 FreeRegionListIterator iter(&local_cleanup_list);
1601 while (iter.more_available()) {
1602 HeapRegion* hr = iter.get_next();
1603 hr_printer->cleanup(hr);
1604 }
1605 }
1606
1607 _cleanup_list->add_ordered(&local_cleanup_list);
1608 assert(local_cleanup_list.is_empty(), "post-condition");
1609
1610 HeapRegionRemSet::finish_cleanup_task(&hrrs_cleanup_task);
1611 }
1612 }
1613 };
1614
1615 void G1ConcurrentMark::cleanup() {
1616 // world is stopped at this checkpoint
1617 assert(SafepointSynchronize::is_at_safepoint(),
1618 "world should be stopped");
1619 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1620
1621 // If a full collection has happened, we shouldn't do this.
1622 if (has_aborted()) {
1623 g1h->collector_state()->set_mark_in_progress(false); // So bitmap clearing isn't confused
1624 return;
1625 }
1626
1627 g1h->verifier()->verify_region_sets_optional();
1628
1629 if (VerifyDuringGC) {
1630 HandleMark hm; // handle scope
1631 g1h->prepare_for_verify();
1632 Universe::verify(VerifyOption_G1UsePrevMarking, "During GC (before)");
1633 }
1634 g1h->verifier()->check_bitmaps("Cleanup Start");
1635
1636 G1CollectorPolicy* g1p = g1h->g1_policy();
1637 g1p->record_concurrent_mark_cleanup_start();
1638
1639 double start = os::elapsedTime();
1640
1641 HeapRegionRemSet::reset_for_cleanup_tasks();
1642
1643 // Do counting once more with the world stopped for good measure.
1644 G1ParFinalCountTask g1_par_count_task(g1h, &_region_bm, &_card_bm);
1645
1646 g1h->workers()->run_task(&g1_par_count_task);
1647
1648 if (VerifyDuringGC) {
1649 // Verify that the counting data accumulated during marking matches
1650 // that calculated by walking the marking bitmap.
1651
1652 // Bitmaps to hold expected values
1653 BitMap expected_region_bm(_region_bm.size(), true);
1654 BitMap expected_card_bm(_card_bm.size(), true);
1655
1656 G1ParVerifyFinalCountTask g1_par_verify_task(g1h,
1657 &_region_bm,
1658 &_card_bm,
1659 &expected_region_bm,
1660 &expected_card_bm);
1661
1662 g1h->workers()->run_task(&g1_par_verify_task);
1663
1664 guarantee(g1_par_verify_task.failures() == 0, "Unexpected accounting failures");
1665 }
1666
1667 size_t start_used_bytes = g1h->used();
1668 g1h->collector_state()->set_mark_in_progress(false);
1669
1670 double count_end = os::elapsedTime();
1671 double this_final_counting_time = (count_end - start);
1672 _total_counting_time += this_final_counting_time;
1673
1674 if (log_is_enabled(Trace, gc, liveness)) {
1675 G1PrintRegionLivenessInfoClosure cl("Post-Marking");
1676 _g1h->heap_region_iterate(&cl);
1677 }
1678
1679 // Install newly created mark bitMap as "prev".
1680 swapMarkBitMaps();
1681
1682 g1h->reset_gc_time_stamp();
1683
1684 uint n_workers = _g1h->workers()->active_workers();
1685
1686 // Note end of marking in all heap regions.
1687 G1ParNoteEndTask g1_par_note_end_task(g1h, &_cleanup_list, n_workers);
1688 g1h->workers()->run_task(&g1_par_note_end_task);
1689 g1h->check_gc_time_stamps();
1690
1691 if (!cleanup_list_is_empty()) {
1692 // The cleanup list is not empty, so we'll have to process it
1693 // concurrently. Notify anyone else that might be wanting free
1694 // regions that there will be more free regions coming soon.
1695 g1h->set_free_regions_coming();
1696 }
1697
1698 // call below, since it affects the metric by which we sort the heap
1699 // regions.
1700 if (G1ScrubRemSets) {
1701 double rs_scrub_start = os::elapsedTime();
1702 g1h->scrub_rem_set(&_region_bm, &_card_bm);
1703 _total_rs_scrub_time += (os::elapsedTime() - rs_scrub_start);
1704 }
1705
1706 // this will also free any regions totally full of garbage objects,
1707 // and sort the regions.
1708 g1h->g1_policy()->record_concurrent_mark_cleanup_end();
1709
1710 // Statistics.
1711 double end = os::elapsedTime();
1712 _cleanup_times.add((end - start) * 1000.0);
1713
1714 // Clean up will have freed any regions completely full of garbage.
1715 // Update the soft reference policy with the new heap occupancy.
1716 Universe::update_heap_info_at_gc();
1717
1718 if (VerifyDuringGC) {
1719 HandleMark hm; // handle scope
1720 g1h->prepare_for_verify();
1721 Universe::verify(VerifyOption_G1UsePrevMarking, "During GC (after)");
1722 }
1723
1724 g1h->verifier()->check_bitmaps("Cleanup End");
1725
1726 g1h->verifier()->verify_region_sets_optional();
1727
1728 // We need to make this be a "collection" so any collection pause that
1729 // races with it goes around and waits for completeCleanup to finish.
1730 g1h->increment_total_collections();
1731
1732 // Clean out dead classes and update Metaspace sizes.
1733 if (ClassUnloadingWithConcurrentMark) {
1734 ClassLoaderDataGraph::purge();
1735 }
1736 MetaspaceGC::compute_new_size();
1737
1738 // We reclaimed old regions so we should calculate the sizes to make
1739 // sure we update the old gen/space data.
1740 g1h->g1mm()->update_sizes();
1741 g1h->allocation_context_stats().update_after_mark();
1742
1743 g1h->trace_heap_after_concurrent_cycle();
1744 }
1745
1746 void G1ConcurrentMark::completeCleanup() {
1747 if (has_aborted()) return;
1748
1749 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1750
1751 _cleanup_list.verify_optional();
1752 FreeRegionList tmp_free_list("Tmp Free List");
1753
1754 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [complete cleanup] : "
1755 "cleanup list has %u entries",
1756 _cleanup_list.length());
1757
1758 // No one else should be accessing the _cleanup_list at this point,
1759 // so it is not necessary to take any locks
1760 while (!_cleanup_list.is_empty()) {
1761 HeapRegion* hr = _cleanup_list.remove_region(true /* from_head */);
1762 assert(hr != NULL, "Got NULL from a non-empty list");
1763 hr->par_clear();
1764 tmp_free_list.add_ordered(hr);
1765
1766 // Instead of adding one region at a time to the secondary_free_list,
1767 // we accumulate them in the local list and move them a few at a
1768 // time. This also cuts down on the number of notify_all() calls
1769 // we do during this process. We'll also append the local list when
1770 // _cleanup_list is empty (which means we just removed the last
1771 // region from the _cleanup_list).
1772 if ((tmp_free_list.length() % G1SecondaryFreeListAppendLength == 0) ||
1773 _cleanup_list.is_empty()) {
1774 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [complete cleanup] : "
1775 "appending %u entries to the secondary_free_list, "
1776 "cleanup list still has %u entries",
1777 tmp_free_list.length(),
1778 _cleanup_list.length());
1779
1780 {
1781 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
1782 g1h->secondary_free_list_add(&tmp_free_list);
1783 SecondaryFreeList_lock->notify_all();
1784 }
1785 #ifndef PRODUCT
1786 if (G1StressConcRegionFreeing) {
1787 for (uintx i = 0; i < G1StressConcRegionFreeingDelayMillis; ++i) {
1788 os::sleep(Thread::current(), (jlong) 1, false);
1789 }
1790 }
1791 #endif
1792 }
1793 }
1794 assert(tmp_free_list.is_empty(), "post-condition");
1795 }
1796
1797 // Supporting Object and Oop closures for reference discovery
1798 // and processing in during marking
1799
1800 bool G1CMIsAliveClosure::do_object_b(oop obj) {
1801 HeapWord* addr = (HeapWord*)obj;
1802 return addr != NULL &&
1803 (!_g1->is_in_g1_reserved(addr) || !_g1->is_obj_ill(obj));
1804 }
1805
1806 // 'Keep Alive' oop closure used by both serial parallel reference processing.
1807 // Uses the G1CMTask associated with a worker thread (for serial reference
1808 // processing the G1CMTask for worker 0 is used) to preserve (mark) and
1809 // trace referent objects.
1810 //
1811 // Using the G1CMTask and embedded local queues avoids having the worker
1812 // threads operating on the global mark stack. This reduces the risk
1813 // of overflowing the stack - which we would rather avoid at this late
1814 // state. Also using the tasks' local queues removes the potential
1815 // of the workers interfering with each other that could occur if
1816 // operating on the global stack.
1817
1818 class G1CMKeepAliveAndDrainClosure: public OopClosure {
1819 G1ConcurrentMark* _cm;
1820 G1CMTask* _task;
1821 int _ref_counter_limit;
1822 int _ref_counter;
1823 bool _is_serial;
1824 public:
1825 G1CMKeepAliveAndDrainClosure(G1ConcurrentMark* cm, G1CMTask* task, bool is_serial) :
1826 _cm(cm), _task(task), _is_serial(is_serial),
1827 _ref_counter_limit(G1RefProcDrainInterval) {
1828 assert(_ref_counter_limit > 0, "sanity");
1829 assert(!_is_serial || _task->worker_id() == 0, "only task 0 for serial code");
1830 _ref_counter = _ref_counter_limit;
1831 }
1832
1833 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
1834 virtual void do_oop( oop* p) { do_oop_work(p); }
1835
1836 template <class T> void do_oop_work(T* p) {
1837 if (!_cm->has_overflown()) {
1838 oop obj = oopDesc::load_decode_heap_oop(p);
1839 _task->deal_with_reference(obj);
1840 _ref_counter--;
1841
1842 if (_ref_counter == 0) {
1843 // We have dealt with _ref_counter_limit references, pushing them
1844 // and objects reachable from them on to the local stack (and
1845 // possibly the global stack). Call G1CMTask::do_marking_step() to
1846 // process these entries.
1847 //
1848 // We call G1CMTask::do_marking_step() in a loop, which we'll exit if
1849 // there's nothing more to do (i.e. we're done with the entries that
1850 // were pushed as a result of the G1CMTask::deal_with_reference() calls
1851 // above) or we overflow.
1852 //
1853 // Note: G1CMTask::do_marking_step() can set the G1CMTask::has_aborted()
1854 // flag while there may still be some work to do. (See the comment at
1855 // the beginning of G1CMTask::do_marking_step() for those conditions -
1856 // one of which is reaching the specified time target.) It is only
1857 // when G1CMTask::do_marking_step() returns without setting the
1858 // has_aborted() flag that the marking step has completed.
1859 do {
1860 double mark_step_duration_ms = G1ConcMarkStepDurationMillis;
1861 _task->do_marking_step(mark_step_duration_ms,
1862 false /* do_termination */,
1863 _is_serial);
1864 } while (_task->has_aborted() && !_cm->has_overflown());
1865 _ref_counter = _ref_counter_limit;
1866 }
1867 }
1868 }
1869 };
1870
1871 // 'Drain' oop closure used by both serial and parallel reference processing.
1872 // Uses the G1CMTask associated with a given worker thread (for serial
1873 // reference processing the G1CMtask for worker 0 is used). Calls the
1874 // do_marking_step routine, with an unbelievably large timeout value,
1875 // to drain the marking data structures of the remaining entries
1876 // added by the 'keep alive' oop closure above.
1877
1878 class G1CMDrainMarkingStackClosure: public VoidClosure {
1879 G1ConcurrentMark* _cm;
1880 G1CMTask* _task;
1881 bool _is_serial;
1882 public:
1883 G1CMDrainMarkingStackClosure(G1ConcurrentMark* cm, G1CMTask* task, bool is_serial) :
1884 _cm(cm), _task(task), _is_serial(is_serial) {
1885 assert(!_is_serial || _task->worker_id() == 0, "only task 0 for serial code");
1886 }
1887
1888 void do_void() {
1889 do {
1890 // We call G1CMTask::do_marking_step() to completely drain the local
1891 // and global marking stacks of entries pushed by the 'keep alive'
1892 // oop closure (an instance of G1CMKeepAliveAndDrainClosure above).
1893 //
1894 // G1CMTask::do_marking_step() is called in a loop, which we'll exit
1895 // if there's nothing more to do (i.e. we've completely drained the
1896 // entries that were pushed as a a result of applying the 'keep alive'
1897 // closure to the entries on the discovered ref lists) or we overflow
1898 // the global marking stack.
1899 //
1900 // Note: G1CMTask::do_marking_step() can set the G1CMTask::has_aborted()
1901 // flag while there may still be some work to do. (See the comment at
1902 // the beginning of G1CMTask::do_marking_step() for those conditions -
1903 // one of which is reaching the specified time target.) It is only
1904 // when G1CMTask::do_marking_step() returns without setting the
1905 // has_aborted() flag that the marking step has completed.
1906
1907 _task->do_marking_step(1000000000.0 /* something very large */,
1908 true /* do_termination */,
1909 _is_serial);
1910 } while (_task->has_aborted() && !_cm->has_overflown());
1911 }
1912 };
1913
1914 // Implementation of AbstractRefProcTaskExecutor for parallel
1915 // reference processing at the end of G1 concurrent marking
1916
1917 class G1CMRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
1918 private:
1919 G1CollectedHeap* _g1h;
1920 G1ConcurrentMark* _cm;
1921 WorkGang* _workers;
1922 uint _active_workers;
1923
1924 public:
1925 G1CMRefProcTaskExecutor(G1CollectedHeap* g1h,
1926 G1ConcurrentMark* cm,
1927 WorkGang* workers,
1928 uint n_workers) :
1929 _g1h(g1h), _cm(cm),
1930 _workers(workers), _active_workers(n_workers) { }
1931
1932 // Executes the given task using concurrent marking worker threads.
1933 virtual void execute(ProcessTask& task);
1934 virtual void execute(EnqueueTask& task);
1935 };
1936
1937 class G1CMRefProcTaskProxy: public AbstractGangTask {
1938 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
1939 ProcessTask& _proc_task;
1940 G1CollectedHeap* _g1h;
1941 G1ConcurrentMark* _cm;
1942
1943 public:
1944 G1CMRefProcTaskProxy(ProcessTask& proc_task,
1945 G1CollectedHeap* g1h,
1946 G1ConcurrentMark* cm) :
1947 AbstractGangTask("Process reference objects in parallel"),
1948 _proc_task(proc_task), _g1h(g1h), _cm(cm) {
1949 ReferenceProcessor* rp = _g1h->ref_processor_cm();
1950 assert(rp->processing_is_mt(), "shouldn't be here otherwise");
1951 }
1952
1953 virtual void work(uint worker_id) {
1954 ResourceMark rm;
1955 HandleMark hm;
1956 G1CMTask* task = _cm->task(worker_id);
1957 G1CMIsAliveClosure g1_is_alive(_g1h);
1958 G1CMKeepAliveAndDrainClosure g1_par_keep_alive(_cm, task, false /* is_serial */);
1959 G1CMDrainMarkingStackClosure g1_par_drain(_cm, task, false /* is_serial */);
1960
1961 _proc_task.work(worker_id, g1_is_alive, g1_par_keep_alive, g1_par_drain);
1962 }
1963 };
1964
1965 void G1CMRefProcTaskExecutor::execute(ProcessTask& proc_task) {
1966 assert(_workers != NULL, "Need parallel worker threads.");
1967 assert(_g1h->ref_processor_cm()->processing_is_mt(), "processing is not MT");
1968
1969 G1CMRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _cm);
1970
1971 // We need to reset the concurrency level before each
1972 // proxy task execution, so that the termination protocol
1973 // and overflow handling in G1CMTask::do_marking_step() knows
1974 // how many workers to wait for.
1975 _cm->set_concurrency(_active_workers);
1976 _workers->run_task(&proc_task_proxy);
1977 }
1978
1979 class G1CMRefEnqueueTaskProxy: public AbstractGangTask {
1980 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
1981 EnqueueTask& _enq_task;
1982
1983 public:
1984 G1CMRefEnqueueTaskProxy(EnqueueTask& enq_task) :
1985 AbstractGangTask("Enqueue reference objects in parallel"),
1986 _enq_task(enq_task) { }
1987
1988 virtual void work(uint worker_id) {
1989 _enq_task.work(worker_id);
1990 }
1991 };
1992
1993 void G1CMRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
1994 assert(_workers != NULL, "Need parallel worker threads.");
1995 assert(_g1h->ref_processor_cm()->processing_is_mt(), "processing is not MT");
1996
1997 G1CMRefEnqueueTaskProxy enq_task_proxy(enq_task);
1998
1999 // Not strictly necessary but...
2000 //
2001 // We need to reset the concurrency level before each
2002 // proxy task execution, so that the termination protocol
2003 // and overflow handling in G1CMTask::do_marking_step() knows
2004 // how many workers to wait for.
2005 _cm->set_concurrency(_active_workers);
2006 _workers->run_task(&enq_task_proxy);
2007 }
2008
2009 void G1ConcurrentMark::weakRefsWorkParallelPart(BoolObjectClosure* is_alive, bool purged_classes) {
2010 G1CollectedHeap::heap()->parallel_cleaning(is_alive, true, true, purged_classes);
2011 }
2012
2013 void G1ConcurrentMark::weakRefsWork(bool clear_all_soft_refs) {
2014 if (has_overflown()) {
2015 // Skip processing the discovered references if we have
2016 // overflown the global marking stack. Reference objects
2017 // only get discovered once so it is OK to not
2018 // de-populate the discovered reference lists. We could have,
2019 // but the only benefit would be that, when marking restarts,
2020 // less reference objects are discovered.
2021 return;
2022 }
2023
2024 ResourceMark rm;
2025 HandleMark hm;
2026
2027 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2028
2029 // Is alive closure.
2030 G1CMIsAliveClosure g1_is_alive(g1h);
2031
2032 // Inner scope to exclude the cleaning of the string and symbol
2033 // tables from the displayed time.
2034 {
2035 GCTraceTime(Debug, gc) trace("Reference Processing", g1h->gc_timer_cm());
2036
2037 ReferenceProcessor* rp = g1h->ref_processor_cm();
2038
2039 // See the comment in G1CollectedHeap::ref_processing_init()
2040 // about how reference processing currently works in G1.
2041
2042 // Set the soft reference policy
2043 rp->setup_policy(clear_all_soft_refs);
2044 assert(_markStack.isEmpty(), "mark stack should be empty");
2045
2046 // Instances of the 'Keep Alive' and 'Complete GC' closures used
2047 // in serial reference processing. Note these closures are also
2048 // used for serially processing (by the the current thread) the
2049 // JNI references during parallel reference processing.
2050 //
2051 // These closures do not need to synchronize with the worker
2052 // threads involved in parallel reference processing as these
2053 // instances are executed serially by the current thread (e.g.
2054 // reference processing is not multi-threaded and is thus
2055 // performed by the current thread instead of a gang worker).
2056 //
2057 // The gang tasks involved in parallel reference processing create
2058 // their own instances of these closures, which do their own
2059 // synchronization among themselves.
2060 G1CMKeepAliveAndDrainClosure g1_keep_alive(this, task(0), true /* is_serial */);
2061 G1CMDrainMarkingStackClosure g1_drain_mark_stack(this, task(0), true /* is_serial */);
2062
2063 // We need at least one active thread. If reference processing
2064 // is not multi-threaded we use the current (VMThread) thread,
2065 // otherwise we use the work gang from the G1CollectedHeap and
2066 // we utilize all the worker threads we can.
2067 bool processing_is_mt = rp->processing_is_mt();
2068 uint active_workers = (processing_is_mt ? g1h->workers()->active_workers() : 1U);
2069 active_workers = MAX2(MIN2(active_workers, _max_worker_id), 1U);
2070
2071 // Parallel processing task executor.
2072 G1CMRefProcTaskExecutor par_task_executor(g1h, this,
2073 g1h->workers(), active_workers);
2074 AbstractRefProcTaskExecutor* executor = (processing_is_mt ? &par_task_executor : NULL);
2075
2076 // Set the concurrency level. The phase was already set prior to
2077 // executing the remark task.
2078 set_concurrency(active_workers);
2079
2080 // Set the degree of MT processing here. If the discovery was done MT,
2081 // the number of threads involved during discovery could differ from
2082 // the number of active workers. This is OK as long as the discovered
2083 // Reference lists are balanced (see balance_all_queues() and balance_queues()).
2084 rp->set_active_mt_degree(active_workers);
2085
2086 // Process the weak references.
2087 const ReferenceProcessorStats& stats =
2088 rp->process_discovered_references(&g1_is_alive,
2089 &g1_keep_alive,
2090 &g1_drain_mark_stack,
2091 executor,
2092 g1h->gc_timer_cm());
2093 g1h->gc_tracer_cm()->report_gc_reference_stats(stats);
2094
2095 // The do_oop work routines of the keep_alive and drain_marking_stack
2096 // oop closures will set the has_overflown flag if we overflow the
2097 // global marking stack.
2098
2099 assert(_markStack.overflow() || _markStack.isEmpty(),
2100 "mark stack should be empty (unless it overflowed)");
2101
2102 if (_markStack.overflow()) {
2103 // This should have been done already when we tried to push an
2104 // entry on to the global mark stack. But let's do it again.
2105 set_has_overflown();
2106 }
2107
2108 assert(rp->num_q() == active_workers, "why not");
2109
2110 rp->enqueue_discovered_references(executor);
2111
2112 rp->verify_no_references_recorded();
2113 assert(!rp->discovery_enabled(), "Post condition");
2114 }
2115
2116 if (has_overflown()) {
2117 // We can not trust g1_is_alive if the marking stack overflowed
2118 return;
2119 }
2120
2121 assert(_markStack.isEmpty(), "Marking should have completed");
2122
2123 // Unload Klasses, String, Symbols, Code Cache, etc.
2124 {
2125 GCTraceTime(Debug, gc) trace("Unloading", g1h->gc_timer_cm());
2126
2127 if (ClassUnloadingWithConcurrentMark) {
2128 bool purged_classes;
2129
2130 {
2131 GCTraceTime(Trace, gc) trace("System Dictionary Unloading", g1h->gc_timer_cm());
2132 purged_classes = SystemDictionary::do_unloading(&g1_is_alive, false /* Defer klass cleaning */);
2133 }
2134
2135 {
2136 GCTraceTime(Trace, gc) trace("Parallel Unloading", g1h->gc_timer_cm());
2137 weakRefsWorkParallelPart(&g1_is_alive, purged_classes);
2138 }
2139 }
2140
2141 if (G1StringDedup::is_enabled()) {
2142 GCTraceTime(Trace, gc) trace("String Deduplication Unlink", g1h->gc_timer_cm());
2143 G1StringDedup::unlink(&g1_is_alive);
2144 }
2145 }
2146 }
2147
2148 void G1ConcurrentMark::swapMarkBitMaps() {
2149 G1CMBitMapRO* temp = _prevMarkBitMap;
2150 _prevMarkBitMap = (G1CMBitMapRO*)_nextMarkBitMap;
2151 _nextMarkBitMap = (G1CMBitMap*) temp;
2152 }
2153
2154 // Closure for marking entries in SATB buffers.
2155 class G1CMSATBBufferClosure : public SATBBufferClosure {
2156 private:
2157 G1CMTask* _task;
2158 G1CollectedHeap* _g1h;
2159
2160 // This is very similar to G1CMTask::deal_with_reference, but with
2161 // more relaxed requirements for the argument, so this must be more
2162 // circumspect about treating the argument as an object.
2163 void do_entry(void* entry) const {
2164 _task->increment_refs_reached();
2165 HeapRegion* hr = _g1h->heap_region_containing(entry);
2166 if (entry < hr->next_top_at_mark_start()) {
2167 // Until we get here, we don't know whether entry refers to a valid
2168 // object; it could instead have been a stale reference.
2169 oop obj = static_cast<oop>(entry);
2170 assert(obj->is_oop(true /* ignore mark word */),
2171 "Invalid oop in SATB buffer: " PTR_FORMAT, p2i(obj));
2172 _task->make_reference_grey(obj, hr);
2173 }
2174 }
2175
2176 public:
2177 G1CMSATBBufferClosure(G1CMTask* task, G1CollectedHeap* g1h)
2178 : _task(task), _g1h(g1h) { }
2179
2180 virtual void do_buffer(void** buffer, size_t size) {
2181 for (size_t i = 0; i < size; ++i) {
2182 do_entry(buffer[i]);
2183 }
2184 }
2185 };
2186
2187 class G1RemarkThreadsClosure : public ThreadClosure {
2188 G1CMSATBBufferClosure _cm_satb_cl;
2189 G1CMOopClosure _cm_cl;
2190 MarkingCodeBlobClosure _code_cl;
2191 int _thread_parity;
2192
2193 public:
2194 G1RemarkThreadsClosure(G1CollectedHeap* g1h, G1CMTask* task) :
2195 _cm_satb_cl(task, g1h),
2196 _cm_cl(g1h, g1h->concurrent_mark(), task),
2197 _code_cl(&_cm_cl, !CodeBlobToOopClosure::FixRelocations),
2198 _thread_parity(Threads::thread_claim_parity()) {}
2199
2200 void do_thread(Thread* thread) {
2201 if (thread->is_Java_thread()) {
2202 if (thread->claim_oops_do(true, _thread_parity)) {
2203 JavaThread* jt = (JavaThread*)thread;
2204
2205 // In theory it should not be neccessary to explicitly walk the nmethods to find roots for concurrent marking
2206 // however the liveness of oops reachable from nmethods have very complex lifecycles:
2207 // * Alive if on the stack of an executing method
2208 // * Weakly reachable otherwise
2209 // Some objects reachable from nmethods, such as the class loader (or klass_holder) of the receiver should be
2210 // live by the SATB invariant but other oops recorded in nmethods may behave differently.
2211 jt->nmethods_do(&_code_cl);
2212
2213 jt->satb_mark_queue().apply_closure_and_empty(&_cm_satb_cl);
2214 }
2215 } else if (thread->is_VM_thread()) {
2216 if (thread->claim_oops_do(true, _thread_parity)) {
2217 JavaThread::satb_mark_queue_set().shared_satb_queue()->apply_closure_and_empty(&_cm_satb_cl);
2218 }
2219 }
2220 }
2221 };
2222
2223 class G1CMRemarkTask: public AbstractGangTask {
2224 private:
2225 G1ConcurrentMark* _cm;
2226 public:
2227 void work(uint worker_id) {
2228 // Since all available tasks are actually started, we should
2229 // only proceed if we're supposed to be active.
2230 if (worker_id < _cm->active_tasks()) {
2231 G1CMTask* task = _cm->task(worker_id);
2232 task->record_start_time();
2233 {
2234 ResourceMark rm;
2235 HandleMark hm;
2236
2237 G1RemarkThreadsClosure threads_f(G1CollectedHeap::heap(), task);
2238 Threads::threads_do(&threads_f);
2239 }
2240
2241 do {
2242 task->do_marking_step(1000000000.0 /* something very large */,
2243 true /* do_termination */,
2244 false /* is_serial */);
2245 } while (task->has_aborted() && !_cm->has_overflown());
2246 // If we overflow, then we do not want to restart. We instead
2247 // want to abort remark and do concurrent marking again.
2248 task->record_end_time();
2249 }
2250 }
2251
2252 G1CMRemarkTask(G1ConcurrentMark* cm, uint active_workers) :
2253 AbstractGangTask("Par Remark"), _cm(cm) {
2254 _cm->terminator()->reset_for_reuse(active_workers);
2255 }
2256 };
2257
2258 void G1ConcurrentMark::checkpointRootsFinalWork() {
2259 ResourceMark rm;
2260 HandleMark hm;
2261 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2262
2263 GCTraceTime(Debug, gc) trace("Finalize Marking", g1h->gc_timer_cm());
2264
2265 g1h->ensure_parsability(false);
2266
2267 // this is remark, so we'll use up all active threads
2268 uint active_workers = g1h->workers()->active_workers();
2269 set_concurrency_and_phase(active_workers, false /* concurrent */);
2270 // Leave _parallel_marking_threads at it's
2271 // value originally calculated in the G1ConcurrentMark
2272 // constructor and pass values of the active workers
2273 // through the gang in the task.
2274
2275 {
2276 StrongRootsScope srs(active_workers);
2277
2278 G1CMRemarkTask remarkTask(this, active_workers);
2279 // We will start all available threads, even if we decide that the
2280 // active_workers will be fewer. The extra ones will just bail out
2281 // immediately.
2282 g1h->workers()->run_task(&remarkTask);
2283 }
2284
2285 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
2286 guarantee(has_overflown() ||
2287 satb_mq_set.completed_buffers_num() == 0,
2288 "Invariant: has_overflown = %s, num buffers = " SIZE_FORMAT,
2289 BOOL_TO_STR(has_overflown()),
2290 satb_mq_set.completed_buffers_num());
2291
2292 print_stats();
2293 }
2294
2295 void G1ConcurrentMark::clearRangePrevBitmap(MemRegion mr) {
2296 // Note we are overriding the read-only view of the prev map here, via
2297 // the cast.
2298 ((G1CMBitMap*)_prevMarkBitMap)->clearRange(mr);
2299 }
2300
2301 HeapRegion*
2302 G1ConcurrentMark::claim_region(uint worker_id) {
2303 // "checkpoint" the finger
2304 HeapWord* finger = _finger;
2305
2306 // _heap_end will not change underneath our feet; it only changes at
2307 // yield points.
2308 while (finger < _heap_end) {
2309 assert(_g1h->is_in_g1_reserved(finger), "invariant");
2310
2311 HeapRegion* curr_region = _g1h->heap_region_containing(finger);
2312
2313 // Above heap_region_containing may return NULL as we always scan claim
2314 // until the end of the heap. In this case, just jump to the next region.
2315 HeapWord* end = curr_region != NULL ? curr_region->end() : finger + HeapRegion::GrainWords;
2316
2317 // Is the gap between reading the finger and doing the CAS too long?
2318 HeapWord* res = (HeapWord*) Atomic::cmpxchg_ptr(end, &_finger, finger);
2319 if (res == finger && curr_region != NULL) {
2320 // we succeeded
2321 HeapWord* bottom = curr_region->bottom();
2322 HeapWord* limit = curr_region->next_top_at_mark_start();
2323
2324 // notice that _finger == end cannot be guaranteed here since,
2325 // someone else might have moved the finger even further
2326 assert(_finger >= end, "the finger should have moved forward");
2327
2328 if (limit > bottom) {
2329 return curr_region;
2330 } else {
2331 assert(limit == bottom,
2332 "the region limit should be at bottom");
2333 // we return NULL and the caller should try calling
2334 // claim_region() again.
2335 return NULL;
2336 }
2337 } else {
2338 assert(_finger > finger, "the finger should have moved forward");
2339 // read it again
2340 finger = _finger;
2341 }
2342 }
2343
2344 return NULL;
2345 }
2346
2347 #ifndef PRODUCT
2348 class VerifyNoCSetOops VALUE_OBJ_CLASS_SPEC {
2349 private:
2350 G1CollectedHeap* _g1h;
2351 const char* _phase;
2352 int _info;
2353
2354 public:
2355 VerifyNoCSetOops(const char* phase, int info = -1) :
2356 _g1h(G1CollectedHeap::heap()),
2357 _phase(phase),
2358 _info(info)
2359 { }
2360
2361 void operator()(oop obj) const {
2362 guarantee(obj->is_oop(),
2363 "Non-oop " PTR_FORMAT ", phase: %s, info: %d",
2364 p2i(obj), _phase, _info);
2365 guarantee(!_g1h->obj_in_cs(obj),
2366 "obj: " PTR_FORMAT " in CSet, phase: %s, info: %d",
2367 p2i(obj), _phase, _info);
2368 }
2369 };
2370
2371 void G1ConcurrentMark::verify_no_cset_oops() {
2372 assert(SafepointSynchronize::is_at_safepoint(), "should be at a safepoint");
2373 if (!G1CollectedHeap::heap()->collector_state()->mark_in_progress()) {
2374 return;
2375 }
2376
2377 // Verify entries on the global mark stack
2378 _markStack.iterate(VerifyNoCSetOops("Stack"));
2379
2380 // Verify entries on the task queues
2381 for (uint i = 0; i < _max_worker_id; ++i) {
2382 G1CMTaskQueue* queue = _task_queues->queue(i);
2383 queue->iterate(VerifyNoCSetOops("Queue", i));
2384 }
2385
2386 // Verify the global finger
2387 HeapWord* global_finger = finger();
2388 if (global_finger != NULL && global_finger < _heap_end) {
2389 // Since we always iterate over all regions, we might get a NULL HeapRegion
2390 // here.
2391 HeapRegion* global_hr = _g1h->heap_region_containing(global_finger);
2392 guarantee(global_hr == NULL || global_finger == global_hr->bottom(),
2393 "global finger: " PTR_FORMAT " region: " HR_FORMAT,
2394 p2i(global_finger), HR_FORMAT_PARAMS(global_hr));
2395 }
2396
2397 // Verify the task fingers
2398 assert(parallel_marking_threads() <= _max_worker_id, "sanity");
2399 for (uint i = 0; i < parallel_marking_threads(); ++i) {
2400 G1CMTask* task = _tasks[i];
2401 HeapWord* task_finger = task->finger();
2402 if (task_finger != NULL && task_finger < _heap_end) {
2403 // See above note on the global finger verification.
2404 HeapRegion* task_hr = _g1h->heap_region_containing(task_finger);
2405 guarantee(task_hr == NULL || task_finger == task_hr->bottom() ||
2406 !task_hr->in_collection_set(),
2407 "task finger: " PTR_FORMAT " region: " HR_FORMAT,
2408 p2i(task_finger), HR_FORMAT_PARAMS(task_hr));
2409 }
2410 }
2411 }
2412 #endif // PRODUCT
2413
2414 // Aggregate the counting data that was constructed concurrently
2415 // with marking.
2416 class AggregateCountDataHRClosure: public HeapRegionClosure {
2417 G1CollectedHeap* _g1h;
2418 G1ConcurrentMark* _cm;
2419 CardTableModRefBS* _ct_bs;
2420 BitMap* _cm_card_bm;
2421 uint _max_worker_id;
2422
2423 public:
2424 AggregateCountDataHRClosure(G1CollectedHeap* g1h,
2425 BitMap* cm_card_bm,
2426 uint max_worker_id) :
2427 _g1h(g1h), _cm(g1h->concurrent_mark()),
2428 _ct_bs(barrier_set_cast<CardTableModRefBS>(g1h->barrier_set())),
2429 _cm_card_bm(cm_card_bm), _max_worker_id(max_worker_id) { }
2430
2431 void doHeapRegion(HeapRegion* hr) {
2432 HeapWord* start = hr->bottom();
2433 HeapWord* limit = hr->next_top_at_mark_start();
2434 HeapWord* end = hr->end();
2435
2436 assert(start <= limit && limit <= hr->top() && hr->top() <= hr->end(),
2437 "Preconditions not met - "
2438 "start: " PTR_FORMAT ", limit: " PTR_FORMAT ", "
2439 "top: " PTR_FORMAT ", end: " PTR_FORMAT,
2440 p2i(start), p2i(limit), p2i(hr->top()), p2i(hr->end()));
2441
2442 assert(hr->next_marked_bytes() == 0, "Precondition");
2443
2444 if (start == limit) {
2445 // NTAMS of this region has not been set so nothing to do.
2446 return;
2447 }
2448
2449 // 'start' should be in the heap.
2450 assert(_g1h->is_in_g1_reserved(start) && _ct_bs->is_card_aligned(start), "sanity");
2451 // 'end' *may* be just beyond the end of the heap (if hr is the last region)
2452 assert(!_g1h->is_in_g1_reserved(end) || _ct_bs->is_card_aligned(end), "sanity");
2453
2454 BitMap::idx_t start_idx = _cm->card_bitmap_index_for(start);
2455 BitMap::idx_t limit_idx = _cm->card_bitmap_index_for(limit);
2456 BitMap::idx_t end_idx = _cm->card_bitmap_index_for(end);
2457
2458 // If ntams is not card aligned then we bump card bitmap index
2459 // for limit so that we get the all the cards spanned by
2460 // the object ending at ntams.
2461 // Note: if this is the last region in the heap then ntams
2462 // could be actually just beyond the end of the the heap;
2463 // limit_idx will then correspond to a (non-existent) card
2464 // that is also outside the heap.
2465 if (_g1h->is_in_g1_reserved(limit) && !_ct_bs->is_card_aligned(limit)) {
2466 limit_idx += 1;
2467 }
2468
2469 assert(limit_idx <= end_idx, "or else use atomics");
2470
2471 // Aggregate the "stripe" in the count data associated with hr.
2472 uint hrm_index = hr->hrm_index();
2473 size_t marked_bytes = 0;
2474
2475 for (uint i = 0; i < _max_worker_id; i += 1) {
2476 size_t* marked_bytes_array = _cm->count_marked_bytes_array_for(i);
2477 BitMap* task_card_bm = _cm->count_card_bitmap_for(i);
2478
2479 // Fetch the marked_bytes in this region for task i and
2480 // add it to the running total for this region.
2481 marked_bytes += marked_bytes_array[hrm_index];
2482
2483 // Now union the bitmaps[0,max_worker_id)[start_idx..limit_idx)
2484 // into the global card bitmap.
2485 BitMap::idx_t scan_idx = task_card_bm->get_next_one_offset(start_idx, limit_idx);
2486
2487 while (scan_idx < limit_idx) {
2488 assert(task_card_bm->at(scan_idx) == true, "should be");
2489 _cm_card_bm->set_bit(scan_idx);
2490 assert(_cm_card_bm->at(scan_idx) == true, "should be");
2491
2492 // BitMap::get_next_one_offset() can handle the case when
2493 // its left_offset parameter is greater than its right_offset
2494 // parameter. It does, however, have an early exit if
2495 // left_offset == right_offset. So let's limit the value
2496 // passed in for left offset here.
2497 BitMap::idx_t next_idx = MIN2(scan_idx + 1, limit_idx);
2498 scan_idx = task_card_bm->get_next_one_offset(next_idx, limit_idx);
2499 }
2500 }
2501
2502 // Update the marked bytes for this region.
2503 hr->add_to_marked_bytes(marked_bytes);
2504 }
2505 };
2506
2507 class G1AggregateCountDataTask: public AbstractGangTask {
2508 protected:
2509 G1CollectedHeap* _g1h;
2510 G1ConcurrentMark* _cm;
2511 BitMap* _cm_card_bm;
2512 uint _max_worker_id;
2513 uint _active_workers;
2514 HeapRegionClaimer _hrclaimer;
2515
2516 public:
2517 G1AggregateCountDataTask(G1CollectedHeap* g1h,
2518 G1ConcurrentMark* cm,
2519 BitMap* cm_card_bm,
2520 uint max_worker_id,
2521 uint n_workers) :
2522 AbstractGangTask("Count Aggregation"),
2523 _g1h(g1h), _cm(cm), _cm_card_bm(cm_card_bm),
2524 _max_worker_id(max_worker_id),
2525 _active_workers(n_workers),
2526 _hrclaimer(_active_workers) {
2527 }
2528
2529 void work(uint worker_id) {
2530 AggregateCountDataHRClosure cl(_g1h, _cm_card_bm, _max_worker_id);
2531
2532 _g1h->heap_region_par_iterate(&cl, worker_id, &_hrclaimer);
2533 }
2534 };
2535
2536
2537 void G1ConcurrentMark::aggregate_count_data() {
2538 uint n_workers = _g1h->workers()->active_workers();
2539
2540 G1AggregateCountDataTask g1_par_agg_task(_g1h, this, &_card_bm,
2541 _max_worker_id, n_workers);
2542
2543 _g1h->workers()->run_task(&g1_par_agg_task);
2544 }
2545
2546 // Clear the per-worker arrays used to store the per-region counting data
2547 void G1ConcurrentMark::clear_all_count_data() {
2548 // Clear the global card bitmap - it will be filled during
2549 // liveness count aggregation (during remark) and the
2550 // final counting task.
2551 _card_bm.clear();
2552
2553 // Clear the global region bitmap - it will be filled as part
2554 // of the final counting task.
2555 _region_bm.clear();
2556
2557 uint max_regions = _g1h->max_regions();
2558 assert(_max_worker_id > 0, "uninitialized");
2559
2560 for (uint i = 0; i < _max_worker_id; i += 1) {
2561 BitMap* task_card_bm = count_card_bitmap_for(i);
2562 size_t* marked_bytes_array = count_marked_bytes_array_for(i);
2563
2564 assert(task_card_bm->size() == _card_bm.size(), "size mismatch");
2565 assert(marked_bytes_array != NULL, "uninitialized");
2566
2567 memset(marked_bytes_array, 0, (size_t) max_regions * sizeof(size_t));
2568 task_card_bm->clear();
2569 }
2570 }
2571
2572 void G1ConcurrentMark::print_stats() {
2573 if (!log_is_enabled(Debug, gc, stats)) {
2574 return;
2575 }
2576 log_debug(gc, stats)("---------------------------------------------------------------------");
2577 for (size_t i = 0; i < _active_tasks; ++i) {
2578 _tasks[i]->print_stats();
2579 log_debug(gc, stats)("---------------------------------------------------------------------");
2580 }
2581 }
2582
2583 // abandon current marking iteration due to a Full GC
2584 void G1ConcurrentMark::abort() {
2585 if (!cmThread()->during_cycle() || _has_aborted) {
2586 // We haven't started a concurrent cycle or we have already aborted it. No need to do anything.
2587 return;
2588 }
2589
2590 // Clear all marks in the next bitmap for the next marking cycle. This will allow us to skip the next
2591 // concurrent bitmap clearing.
2592 _nextMarkBitMap->clearAll();
2593
2594 // Note we cannot clear the previous marking bitmap here
2595 // since VerifyDuringGC verifies the objects marked during
2596 // a full GC against the previous bitmap.
2597
2598 // Clear the liveness counting data
2599 clear_all_count_data();
2600 // Empty mark stack
2601 reset_marking_state();
2602 for (uint i = 0; i < _max_worker_id; ++i) {
2603 _tasks[i]->clear_region_fields();
2604 }
2605 _first_overflow_barrier_sync.abort();
2606 _second_overflow_barrier_sync.abort();
2607 _has_aborted = true;
2608
2609 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
2610 satb_mq_set.abandon_partial_marking();
2611 // This can be called either during or outside marking, we'll read
2612 // the expected_active value from the SATB queue set.
2613 satb_mq_set.set_active_all_threads(
2614 false, /* new active value */
2615 satb_mq_set.is_active() /* expected_active */);
2616
2617 _g1h->trace_heap_after_concurrent_cycle();
2618
2619 _g1h->register_concurrent_cycle_end();
2620 }
2621
2622 static void print_ms_time_info(const char* prefix, const char* name,
2623 NumberSeq& ns) {
2624 log_trace(gc, marking)("%s%5d %12s: total time = %8.2f s (avg = %8.2f ms).",
2625 prefix, ns.num(), name, ns.sum()/1000.0, ns.avg());
2626 if (ns.num() > 0) {
2627 log_trace(gc, marking)("%s [std. dev = %8.2f ms, max = %8.2f ms]",
2628 prefix, ns.sd(), ns.maximum());
2629 }
2630 }
2631
2632 void G1ConcurrentMark::print_summary_info() {
2633 LogHandle(gc, marking) log;
2634 if (!log.is_trace()) {
2635 return;
2636 }
2637
2638 log.trace(" Concurrent marking:");
2639 print_ms_time_info(" ", "init marks", _init_times);
2640 print_ms_time_info(" ", "remarks", _remark_times);
2641 {
2642 print_ms_time_info(" ", "final marks", _remark_mark_times);
2643 print_ms_time_info(" ", "weak refs", _remark_weak_ref_times);
2644
2645 }
2646 print_ms_time_info(" ", "cleanups", _cleanup_times);
2647 log.trace(" Final counting total time = %8.2f s (avg = %8.2f ms).",
2648 _total_counting_time, (_cleanup_times.num() > 0 ? _total_counting_time * 1000.0 / (double)_cleanup_times.num() : 0.0));
2649 if (G1ScrubRemSets) {
2650 log.trace(" RS scrub total time = %8.2f s (avg = %8.2f ms).",
2651 _total_rs_scrub_time, (_cleanup_times.num() > 0 ? _total_rs_scrub_time * 1000.0 / (double)_cleanup_times.num() : 0.0));
2652 }
2653 log.trace(" Total stop_world time = %8.2f s.",
2654 (_init_times.sum() + _remark_times.sum() + _cleanup_times.sum())/1000.0);
2655 log.trace(" Total concurrent time = %8.2f s (%8.2f s marking).",
2656 cmThread()->vtime_accum(), cmThread()->vtime_mark_accum());
2657 }
2658
2659 void G1ConcurrentMark::print_worker_threads_on(outputStream* st) const {
2660 _parallel_workers->print_worker_threads_on(st);
2661 }
2662
2663 void G1ConcurrentMark::print_on_error(outputStream* st) const {
2664 st->print_cr("Marking Bits (Prev, Next): (CMBitMap*) " PTR_FORMAT ", (CMBitMap*) " PTR_FORMAT,
2665 p2i(_prevMarkBitMap), p2i(_nextMarkBitMap));
2666 _prevMarkBitMap->print_on_error(st, " Prev Bits: ");
2667 _nextMarkBitMap->print_on_error(st, " Next Bits: ");
2668 }
2669
2670 // We take a break if someone is trying to stop the world.
2671 bool G1ConcurrentMark::do_yield_check(uint worker_id) {
2672 if (SuspendibleThreadSet::should_yield()) {
2673 SuspendibleThreadSet::yield();
2674 return true;
2675 } else {
2676 return false;
2677 }
2678 }
2679
2680 // Closure for iteration over bitmaps
2681 class G1CMBitMapClosure : public BitMapClosure {
2682 private:
2683 // the bitmap that is being iterated over
2684 G1CMBitMap* _nextMarkBitMap;
2685 G1ConcurrentMark* _cm;
2686 G1CMTask* _task;
2687
2688 public:
2689 G1CMBitMapClosure(G1CMTask *task, G1ConcurrentMark* cm, G1CMBitMap* nextMarkBitMap) :
2690 _task(task), _cm(cm), _nextMarkBitMap(nextMarkBitMap) { }
2691
2692 bool do_bit(size_t offset) {
2693 HeapWord* addr = _nextMarkBitMap->offsetToHeapWord(offset);
2694 assert(_nextMarkBitMap->isMarked(addr), "invariant");
2695 assert( addr < _cm->finger(), "invariant");
2696 assert(addr >= _task->finger(), "invariant");
2697
2698 // We move that task's local finger along.
2699 _task->move_finger_to(addr);
2700
2701 _task->scan_object(oop(addr));
2702 // we only partially drain the local queue and global stack
2703 _task->drain_local_queue(true);
2704 _task->drain_global_stack(true);
2705
2706 // if the has_aborted flag has been raised, we need to bail out of
2707 // the iteration
2708 return !_task->has_aborted();
2709 }
2710 };
2711
2712 static ReferenceProcessor* get_cm_oop_closure_ref_processor(G1CollectedHeap* g1h) {
2713 ReferenceProcessor* result = g1h->ref_processor_cm();
2714 assert(result != NULL, "CM reference processor should not be NULL");
2715 return result;
2716 }
2717
2718 G1CMOopClosure::G1CMOopClosure(G1CollectedHeap* g1h,
2719 G1ConcurrentMark* cm,
2720 G1CMTask* task)
2721 : MetadataAwareOopClosure(get_cm_oop_closure_ref_processor(g1h)),
2722 _g1h(g1h), _cm(cm), _task(task)
2723 { }
2724
2725 void G1CMTask::setup_for_region(HeapRegion* hr) {
2726 assert(hr != NULL,
2727 "claim_region() should have filtered out NULL regions");
2728 _curr_region = hr;
2729 _finger = hr->bottom();
2730 update_region_limit();
2731 }
2732
2733 void G1CMTask::update_region_limit() {
2734 HeapRegion* hr = _curr_region;
2735 HeapWord* bottom = hr->bottom();
2736 HeapWord* limit = hr->next_top_at_mark_start();
2737
2738 if (limit == bottom) {
2739 // The region was collected underneath our feet.
2740 // We set the finger to bottom to ensure that the bitmap
2741 // iteration that will follow this will not do anything.
2742 // (this is not a condition that holds when we set the region up,
2743 // as the region is not supposed to be empty in the first place)
2744 _finger = bottom;
2745 } else if (limit >= _region_limit) {
2746 assert(limit >= _finger, "peace of mind");
2747 } else {
2748 assert(limit < _region_limit, "only way to get here");
2749 // This can happen under some pretty unusual circumstances. An
2750 // evacuation pause empties the region underneath our feet (NTAMS
2751 // at bottom). We then do some allocation in the region (NTAMS
2752 // stays at bottom), followed by the region being used as a GC
2753 // alloc region (NTAMS will move to top() and the objects
2754 // originally below it will be grayed). All objects now marked in
2755 // the region are explicitly grayed, if below the global finger,
2756 // and we do not need in fact to scan anything else. So, we simply
2757 // set _finger to be limit to ensure that the bitmap iteration
2758 // doesn't do anything.
2759 _finger = limit;
2760 }
2761
2762 _region_limit = limit;
2763 }
2764
2765 void G1CMTask::giveup_current_region() {
2766 assert(_curr_region != NULL, "invariant");
2767 clear_region_fields();
2768 }
2769
2770 void G1CMTask::clear_region_fields() {
2771 // Values for these three fields that indicate that we're not
2772 // holding on to a region.
2773 _curr_region = NULL;
2774 _finger = NULL;
2775 _region_limit = NULL;
2776 }
2777
2778 void G1CMTask::set_cm_oop_closure(G1CMOopClosure* cm_oop_closure) {
2779 if (cm_oop_closure == NULL) {
2780 assert(_cm_oop_closure != NULL, "invariant");
2781 } else {
2782 assert(_cm_oop_closure == NULL, "invariant");
2783 }
2784 _cm_oop_closure = cm_oop_closure;
2785 }
2786
2787 void G1CMTask::reset(G1CMBitMap* nextMarkBitMap) {
2788 guarantee(nextMarkBitMap != NULL, "invariant");
2789 _nextMarkBitMap = nextMarkBitMap;
2790 clear_region_fields();
2791
2792 _calls = 0;
2793 _elapsed_time_ms = 0.0;
2794 _termination_time_ms = 0.0;
2795 _termination_start_time_ms = 0.0;
2796 }
2797
2798 bool G1CMTask::should_exit_termination() {
2799 regular_clock_call();
2800 // This is called when we are in the termination protocol. We should
2801 // quit if, for some reason, this task wants to abort or the global
2802 // stack is not empty (this means that we can get work from it).
2803 return !_cm->mark_stack_empty() || has_aborted();
2804 }
2805
2806 void G1CMTask::reached_limit() {
2807 assert(_words_scanned >= _words_scanned_limit ||
2808 _refs_reached >= _refs_reached_limit ,
2809 "shouldn't have been called otherwise");
2810 regular_clock_call();
2811 }
2812
2813 void G1CMTask::regular_clock_call() {
2814 if (has_aborted()) return;
2815
2816 // First, we need to recalculate the words scanned and refs reached
2817 // limits for the next clock call.
2818 recalculate_limits();
2819
2820 // During the regular clock call we do the following
2821
2822 // (1) If an overflow has been flagged, then we abort.
2823 if (_cm->has_overflown()) {
2824 set_has_aborted();
2825 return;
2826 }
2827
2828 // If we are not concurrent (i.e. we're doing remark) we don't need
2829 // to check anything else. The other steps are only needed during
2830 // the concurrent marking phase.
2831 if (!concurrent()) return;
2832
2833 // (2) If marking has been aborted for Full GC, then we also abort.
2834 if (_cm->has_aborted()) {
2835 set_has_aborted();
2836 return;
2837 }
2838
2839 double curr_time_ms = os::elapsedVTime() * 1000.0;
2840
2841 // (4) We check whether we should yield. If we have to, then we abort.
2842 if (SuspendibleThreadSet::should_yield()) {
2843 // We should yield. To do this we abort the task. The caller is
2844 // responsible for yielding.
2845 set_has_aborted();
2846 return;
2847 }
2848
2849 // (5) We check whether we've reached our time quota. If we have,
2850 // then we abort.
2851 double elapsed_time_ms = curr_time_ms - _start_time_ms;
2852 if (elapsed_time_ms > _time_target_ms) {
2853 set_has_aborted();
2854 _has_timed_out = true;
2855 return;
2856 }
2857
2858 // (6) Finally, we check whether there are enough completed STAB
2859 // buffers available for processing. If there are, we abort.
2860 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
2861 if (!_draining_satb_buffers && satb_mq_set.process_completed_buffers()) {
2862 // we do need to process SATB buffers, we'll abort and restart
2863 // the marking task to do so
2864 set_has_aborted();
2865 return;
2866 }
2867 }
2868
2869 void G1CMTask::recalculate_limits() {
2870 _real_words_scanned_limit = _words_scanned + words_scanned_period;
2871 _words_scanned_limit = _real_words_scanned_limit;
2872
2873 _real_refs_reached_limit = _refs_reached + refs_reached_period;
2874 _refs_reached_limit = _real_refs_reached_limit;
2875 }
2876
2877 void G1CMTask::decrease_limits() {
2878 // This is called when we believe that we're going to do an infrequent
2879 // operation which will increase the per byte scanned cost (i.e. move
2880 // entries to/from the global stack). It basically tries to decrease the
2881 // scanning limit so that the clock is called earlier.
2882
2883 _words_scanned_limit = _real_words_scanned_limit -
2884 3 * words_scanned_period / 4;
2885 _refs_reached_limit = _real_refs_reached_limit -
2886 3 * refs_reached_period / 4;
2887 }
2888
2889 void G1CMTask::move_entries_to_global_stack() {
2890 // local array where we'll store the entries that will be popped
2891 // from the local queue
2892 oop buffer[global_stack_transfer_size];
2893
2894 int n = 0;
2895 oop obj;
2896 while (n < global_stack_transfer_size && _task_queue->pop_local(obj)) {
2897 buffer[n] = obj;
2898 ++n;
2899 }
2900
2901 if (n > 0) {
2902 // we popped at least one entry from the local queue
2903
2904 if (!_cm->mark_stack_push(buffer, n)) {
2905 set_has_aborted();
2906 }
2907 }
2908
2909 // this operation was quite expensive, so decrease the limits
2910 decrease_limits();
2911 }
2912
2913 void G1CMTask::get_entries_from_global_stack() {
2914 // local array where we'll store the entries that will be popped
2915 // from the global stack.
2916 oop buffer[global_stack_transfer_size];
2917 int n;
2918 _cm->mark_stack_pop(buffer, global_stack_transfer_size, &n);
2919 assert(n <= global_stack_transfer_size,
2920 "we should not pop more than the given limit");
2921 if (n > 0) {
2922 // yes, we did actually pop at least one entry
2923 for (int i = 0; i < n; ++i) {
2924 bool success = _task_queue->push(buffer[i]);
2925 // We only call this when the local queue is empty or under a
2926 // given target limit. So, we do not expect this push to fail.
2927 assert(success, "invariant");
2928 }
2929 }
2930
2931 // this operation was quite expensive, so decrease the limits
2932 decrease_limits();
2933 }
2934
2935 void G1CMTask::drain_local_queue(bool partially) {
2936 if (has_aborted()) return;
2937
2938 // Decide what the target size is, depending whether we're going to
2939 // drain it partially (so that other tasks can steal if they run out
2940 // of things to do) or totally (at the very end).
2941 size_t target_size;
2942 if (partially) {
2943 target_size = MIN2((size_t)_task_queue->max_elems()/3, GCDrainStackTargetSize);
2944 } else {
2945 target_size = 0;
2946 }
2947
2948 if (_task_queue->size() > target_size) {
2949 oop obj;
2950 bool ret = _task_queue->pop_local(obj);
2951 while (ret) {
2952 assert(_g1h->is_in_g1_reserved((HeapWord*) obj), "invariant" );
2953 assert(!_g1h->is_on_master_free_list(
2954 _g1h->heap_region_containing((HeapWord*) obj)), "invariant");
2955
2956 scan_object(obj);
2957
2958 if (_task_queue->size() <= target_size || has_aborted()) {
2959 ret = false;
2960 } else {
2961 ret = _task_queue->pop_local(obj);
2962 }
2963 }
2964 }
2965 }
2966
2967 void G1CMTask::drain_global_stack(bool partially) {
2968 if (has_aborted()) return;
2969
2970 // We have a policy to drain the local queue before we attempt to
2971 // drain the global stack.
2972 assert(partially || _task_queue->size() == 0, "invariant");
2973
2974 // Decide what the target size is, depending whether we're going to
2975 // drain it partially (so that other tasks can steal if they run out
2976 // of things to do) or totally (at the very end). Notice that,
2977 // because we move entries from the global stack in chunks or
2978 // because another task might be doing the same, we might in fact
2979 // drop below the target. But, this is not a problem.
2980 size_t target_size;
2981 if (partially) {
2982 target_size = _cm->partial_mark_stack_size_target();
2983 } else {
2984 target_size = 0;
2985 }
2986
2987 if (_cm->mark_stack_size() > target_size) {
2988 while (!has_aborted() && _cm->mark_stack_size() > target_size) {
2989 get_entries_from_global_stack();
2990 drain_local_queue(partially);
2991 }
2992 }
2993 }
2994
2995 // SATB Queue has several assumptions on whether to call the par or
2996 // non-par versions of the methods. this is why some of the code is
2997 // replicated. We should really get rid of the single-threaded version
2998 // of the code to simplify things.
2999 void G1CMTask::drain_satb_buffers() {
3000 if (has_aborted()) return;
3001
3002 // We set this so that the regular clock knows that we're in the
3003 // middle of draining buffers and doesn't set the abort flag when it
3004 // notices that SATB buffers are available for draining. It'd be
3005 // very counter productive if it did that. :-)
3006 _draining_satb_buffers = true;
3007
3008 G1CMSATBBufferClosure satb_cl(this, _g1h);
3009 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
3010
3011 // This keeps claiming and applying the closure to completed buffers
3012 // until we run out of buffers or we need to abort.
3013 while (!has_aborted() &&
3014 satb_mq_set.apply_closure_to_completed_buffer(&satb_cl)) {
3015 regular_clock_call();
3016 }
3017
3018 _draining_satb_buffers = false;
3019
3020 assert(has_aborted() ||
3021 concurrent() ||
3022 satb_mq_set.completed_buffers_num() == 0, "invariant");
3023
3024 // again, this was a potentially expensive operation, decrease the
3025 // limits to get the regular clock call early
3026 decrease_limits();
3027 }
3028
3029 void G1CMTask::print_stats() {
3030 log_debug(gc, stats)("Marking Stats, task = %u, calls = %d",
3031 _worker_id, _calls);
3032 log_debug(gc, stats)(" Elapsed time = %1.2lfms, Termination time = %1.2lfms",
3033 _elapsed_time_ms, _termination_time_ms);
3034 log_debug(gc, stats)(" Step Times (cum): num = %d, avg = %1.2lfms, sd = %1.2lfms",
3035 _step_times_ms.num(), _step_times_ms.avg(),
3036 _step_times_ms.sd());
3037 log_debug(gc, stats)(" max = %1.2lfms, total = %1.2lfms",
3038 _step_times_ms.maximum(), _step_times_ms.sum());
3039 }
3040
3041 bool G1ConcurrentMark::try_stealing(uint worker_id, int* hash_seed, oop& obj) {
3042 return _task_queues->steal(worker_id, hash_seed, obj);
3043 }
3044
3045 /*****************************************************************************
3046
3047 The do_marking_step(time_target_ms, ...) method is the building
3048 block of the parallel marking framework. It can be called in parallel
3049 with other invocations of do_marking_step() on different tasks
3050 (but only one per task, obviously) and concurrently with the
3051 mutator threads, or during remark, hence it eliminates the need
3052 for two versions of the code. When called during remark, it will
3053 pick up from where the task left off during the concurrent marking
3054 phase. Interestingly, tasks are also claimable during evacuation
3055 pauses too, since do_marking_step() ensures that it aborts before
3056 it needs to yield.
3057
3058 The data structures that it uses to do marking work are the
3059 following:
3060
3061 (1) Marking Bitmap. If there are gray objects that appear only
3062 on the bitmap (this happens either when dealing with an overflow
3063 or when the initial marking phase has simply marked the roots
3064 and didn't push them on the stack), then tasks claim heap
3065 regions whose bitmap they then scan to find gray objects. A
3066 global finger indicates where the end of the last claimed region
3067 is. A local finger indicates how far into the region a task has
3068 scanned. The two fingers are used to determine how to gray an
3069 object (i.e. whether simply marking it is OK, as it will be
3070 visited by a task in the future, or whether it needs to be also
3071 pushed on a stack).
3072
3073 (2) Local Queue. The local queue of the task which is accessed
3074 reasonably efficiently by the task. Other tasks can steal from
3075 it when they run out of work. Throughout the marking phase, a
3076 task attempts to keep its local queue short but not totally
3077 empty, so that entries are available for stealing by other
3078 tasks. Only when there is no more work, a task will totally
3079 drain its local queue.
3080
3081 (3) Global Mark Stack. This handles local queue overflow. During
3082 marking only sets of entries are moved between it and the local
3083 queues, as access to it requires a mutex and more fine-grain
3084 interaction with it which might cause contention. If it
3085 overflows, then the marking phase should restart and iterate
3086 over the bitmap to identify gray objects. Throughout the marking
3087 phase, tasks attempt to keep the global mark stack at a small
3088 length but not totally empty, so that entries are available for
3089 popping by other tasks. Only when there is no more work, tasks
3090 will totally drain the global mark stack.
3091
3092 (4) SATB Buffer Queue. This is where completed SATB buffers are
3093 made available. Buffers are regularly removed from this queue
3094 and scanned for roots, so that the queue doesn't get too
3095 long. During remark, all completed buffers are processed, as
3096 well as the filled in parts of any uncompleted buffers.
3097
3098 The do_marking_step() method tries to abort when the time target
3099 has been reached. There are a few other cases when the
3100 do_marking_step() method also aborts:
3101
3102 (1) When the marking phase has been aborted (after a Full GC).
3103
3104 (2) When a global overflow (on the global stack) has been
3105 triggered. Before the task aborts, it will actually sync up with
3106 the other tasks to ensure that all the marking data structures
3107 (local queues, stacks, fingers etc.) are re-initialized so that
3108 when do_marking_step() completes, the marking phase can
3109 immediately restart.
3110
3111 (3) When enough completed SATB buffers are available. The
3112 do_marking_step() method only tries to drain SATB buffers right
3113 at the beginning. So, if enough buffers are available, the
3114 marking step aborts and the SATB buffers are processed at
3115 the beginning of the next invocation.
3116
3117 (4) To yield. when we have to yield then we abort and yield
3118 right at the end of do_marking_step(). This saves us from a lot
3119 of hassle as, by yielding we might allow a Full GC. If this
3120 happens then objects will be compacted underneath our feet, the
3121 heap might shrink, etc. We save checking for this by just
3122 aborting and doing the yield right at the end.
3123
3124 From the above it follows that the do_marking_step() method should
3125 be called in a loop (or, otherwise, regularly) until it completes.
3126
3127 If a marking step completes without its has_aborted() flag being
3128 true, it means it has completed the current marking phase (and
3129 also all other marking tasks have done so and have all synced up).
3130
3131 A method called regular_clock_call() is invoked "regularly" (in
3132 sub ms intervals) throughout marking. It is this clock method that
3133 checks all the abort conditions which were mentioned above and
3134 decides when the task should abort. A work-based scheme is used to
3135 trigger this clock method: when the number of object words the
3136 marking phase has scanned or the number of references the marking
3137 phase has visited reach a given limit. Additional invocations to
3138 the method clock have been planted in a few other strategic places
3139 too. The initial reason for the clock method was to avoid calling
3140 vtime too regularly, as it is quite expensive. So, once it was in
3141 place, it was natural to piggy-back all the other conditions on it
3142 too and not constantly check them throughout the code.
3143
3144 If do_termination is true then do_marking_step will enter its
3145 termination protocol.
3146
3147 The value of is_serial must be true when do_marking_step is being
3148 called serially (i.e. by the VMThread) and do_marking_step should
3149 skip any synchronization in the termination and overflow code.
3150 Examples include the serial remark code and the serial reference
3151 processing closures.
3152
3153 The value of is_serial must be false when do_marking_step is
3154 being called by any of the worker threads in a work gang.
3155 Examples include the concurrent marking code (CMMarkingTask),
3156 the MT remark code, and the MT reference processing closures.
3157
3158 *****************************************************************************/
3159
3160 void G1CMTask::do_marking_step(double time_target_ms,
3161 bool do_termination,
3162 bool is_serial) {
3163 assert(time_target_ms >= 1.0, "minimum granularity is 1ms");
3164 assert(concurrent() == _cm->concurrent(), "they should be the same");
3165
3166 G1CollectorPolicy* g1_policy = _g1h->g1_policy();
3167 assert(_task_queues != NULL, "invariant");
3168 assert(_task_queue != NULL, "invariant");
3169 assert(_task_queues->queue(_worker_id) == _task_queue, "invariant");
3170
3171 assert(!_claimed,
3172 "only one thread should claim this task at any one time");
3173
3174 // OK, this doesn't safeguard again all possible scenarios, as it is
3175 // possible for two threads to set the _claimed flag at the same
3176 // time. But it is only for debugging purposes anyway and it will
3177 // catch most problems.
3178 _claimed = true;
3179
3180 _start_time_ms = os::elapsedVTime() * 1000.0;
3181
3182 // If do_stealing is true then do_marking_step will attempt to
3183 // steal work from the other G1CMTasks. It only makes sense to
3184 // enable stealing when the termination protocol is enabled
3185 // and do_marking_step() is not being called serially.
3186 bool do_stealing = do_termination && !is_serial;
3187
3188 double diff_prediction_ms = _g1h->g1_policy()->predictor().get_new_prediction(&_marking_step_diffs_ms);
3189 _time_target_ms = time_target_ms - diff_prediction_ms;
3190
3191 // set up the variables that are used in the work-based scheme to
3192 // call the regular clock method
3193 _words_scanned = 0;
3194 _refs_reached = 0;
3195 recalculate_limits();
3196
3197 // clear all flags
3198 clear_has_aborted();
3199 _has_timed_out = false;
3200 _draining_satb_buffers = false;
3201
3202 ++_calls;
3203
3204 // Set up the bitmap and oop closures. Anything that uses them is
3205 // eventually called from this method, so it is OK to allocate these
3206 // statically.
3207 G1CMBitMapClosure bitmap_closure(this, _cm, _nextMarkBitMap);
3208 G1CMOopClosure cm_oop_closure(_g1h, _cm, this);
3209 set_cm_oop_closure(&cm_oop_closure);
3210
3211 if (_cm->has_overflown()) {
3212 // This can happen if the mark stack overflows during a GC pause
3213 // and this task, after a yield point, restarts. We have to abort
3214 // as we need to get into the overflow protocol which happens
3215 // right at the end of this task.
3216 set_has_aborted();
3217 }
3218
3219 // First drain any available SATB buffers. After this, we will not
3220 // look at SATB buffers before the next invocation of this method.
3221 // If enough completed SATB buffers are queued up, the regular clock
3222 // will abort this task so that it restarts.
3223 drain_satb_buffers();
3224 // ...then partially drain the local queue and the global stack
3225 drain_local_queue(true);
3226 drain_global_stack(true);
3227
3228 do {
3229 if (!has_aborted() && _curr_region != NULL) {
3230 // This means that we're already holding on to a region.
3231 assert(_finger != NULL, "if region is not NULL, then the finger "
3232 "should not be NULL either");
3233
3234 // We might have restarted this task after an evacuation pause
3235 // which might have evacuated the region we're holding on to
3236 // underneath our feet. Let's read its limit again to make sure
3237 // that we do not iterate over a region of the heap that
3238 // contains garbage (update_region_limit() will also move
3239 // _finger to the start of the region if it is found empty).
3240 update_region_limit();
3241 // We will start from _finger not from the start of the region,
3242 // as we might be restarting this task after aborting half-way
3243 // through scanning this region. In this case, _finger points to
3244 // the address where we last found a marked object. If this is a
3245 // fresh region, _finger points to start().
3246 MemRegion mr = MemRegion(_finger, _region_limit);
3247
3248 assert(!_curr_region->is_humongous() || mr.start() == _curr_region->bottom(),
3249 "humongous regions should go around loop once only");
3250
3251 // Some special cases:
3252 // If the memory region is empty, we can just give up the region.
3253 // If the current region is humongous then we only need to check
3254 // the bitmap for the bit associated with the start of the object,
3255 // scan the object if it's live, and give up the region.
3256 // Otherwise, let's iterate over the bitmap of the part of the region
3257 // that is left.
3258 // If the iteration is successful, give up the region.
3259 if (mr.is_empty()) {
3260 giveup_current_region();
3261 regular_clock_call();
3262 } else if (_curr_region->is_humongous() && mr.start() == _curr_region->bottom()) {
3263 if (_nextMarkBitMap->isMarked(mr.start())) {
3264 // The object is marked - apply the closure
3265 BitMap::idx_t offset = _nextMarkBitMap->heapWordToOffset(mr.start());
3266 bitmap_closure.do_bit(offset);
3267 }
3268 // Even if this task aborted while scanning the humongous object
3269 // we can (and should) give up the current region.
3270 giveup_current_region();
3271 regular_clock_call();
3272 } else if (_nextMarkBitMap->iterate(&bitmap_closure, mr)) {
3273 giveup_current_region();
3274 regular_clock_call();
3275 } else {
3276 assert(has_aborted(), "currently the only way to do so");
3277 // The only way to abort the bitmap iteration is to return
3278 // false from the do_bit() method. However, inside the
3279 // do_bit() method we move the _finger to point to the
3280 // object currently being looked at. So, if we bail out, we
3281 // have definitely set _finger to something non-null.
3282 assert(_finger != NULL, "invariant");
3283
3284 // Region iteration was actually aborted. So now _finger
3285 // points to the address of the object we last scanned. If we
3286 // leave it there, when we restart this task, we will rescan
3287 // the object. It is easy to avoid this. We move the finger by
3288 // enough to point to the next possible object header (the
3289 // bitmap knows by how much we need to move it as it knows its
3290 // granularity).
3291 assert(_finger < _region_limit, "invariant");
3292 HeapWord* new_finger = _nextMarkBitMap->nextObject(_finger);
3293 // Check if bitmap iteration was aborted while scanning the last object
3294 if (new_finger >= _region_limit) {
3295 giveup_current_region();
3296 } else {
3297 move_finger_to(new_finger);
3298 }
3299 }
3300 }
3301 // At this point we have either completed iterating over the
3302 // region we were holding on to, or we have aborted.
3303
3304 // We then partially drain the local queue and the global stack.
3305 // (Do we really need this?)
3306 drain_local_queue(true);
3307 drain_global_stack(true);
3308
3309 // Read the note on the claim_region() method on why it might
3310 // return NULL with potentially more regions available for
3311 // claiming and why we have to check out_of_regions() to determine
3312 // whether we're done or not.
3313 while (!has_aborted() && _curr_region == NULL && !_cm->out_of_regions()) {
3314 // We are going to try to claim a new region. We should have
3315 // given up on the previous one.
3316 // Separated the asserts so that we know which one fires.
3317 assert(_curr_region == NULL, "invariant");
3318 assert(_finger == NULL, "invariant");
3319 assert(_region_limit == NULL, "invariant");
3320 HeapRegion* claimed_region = _cm->claim_region(_worker_id);
3321 if (claimed_region != NULL) {
3322 // Yes, we managed to claim one
3323 setup_for_region(claimed_region);
3324 assert(_curr_region == claimed_region, "invariant");
3325 }
3326 // It is important to call the regular clock here. It might take
3327 // a while to claim a region if, for example, we hit a large
3328 // block of empty regions. So we need to call the regular clock
3329 // method once round the loop to make sure it's called
3330 // frequently enough.
3331 regular_clock_call();
3332 }
3333
3334 if (!has_aborted() && _curr_region == NULL) {
3335 assert(_cm->out_of_regions(),
3336 "at this point we should be out of regions");
3337 }
3338 } while ( _curr_region != NULL && !has_aborted());
3339
3340 if (!has_aborted()) {
3341 // We cannot check whether the global stack is empty, since other
3342 // tasks might be pushing objects to it concurrently.
3343 assert(_cm->out_of_regions(),
3344 "at this point we should be out of regions");
3345 // Try to reduce the number of available SATB buffers so that
3346 // remark has less work to do.
3347 drain_satb_buffers();
3348 }
3349
3350 // Since we've done everything else, we can now totally drain the
3351 // local queue and global stack.
3352 drain_local_queue(false);
3353 drain_global_stack(false);
3354
3355 // Attempt at work stealing from other task's queues.
3356 if (do_stealing && !has_aborted()) {
3357 // We have not aborted. This means that we have finished all that
3358 // we could. Let's try to do some stealing...
3359
3360 // We cannot check whether the global stack is empty, since other
3361 // tasks might be pushing objects to it concurrently.
3362 assert(_cm->out_of_regions() && _task_queue->size() == 0,
3363 "only way to reach here");
3364 while (!has_aborted()) {
3365 oop obj;
3366 if (_cm->try_stealing(_worker_id, &_hash_seed, obj)) {
3367 assert(_nextMarkBitMap->isMarked((HeapWord*) obj),
3368 "any stolen object should be marked");
3369 scan_object(obj);
3370
3371 // And since we're towards the end, let's totally drain the
3372 // local queue and global stack.
3373 drain_local_queue(false);
3374 drain_global_stack(false);
3375 } else {
3376 break;
3377 }
3378 }
3379 }
3380
3381 // We still haven't aborted. Now, let's try to get into the
3382 // termination protocol.
3383 if (do_termination && !has_aborted()) {
3384 // We cannot check whether the global stack is empty, since other
3385 // tasks might be concurrently pushing objects on it.
3386 // Separated the asserts so that we know which one fires.
3387 assert(_cm->out_of_regions(), "only way to reach here");
3388 assert(_task_queue->size() == 0, "only way to reach here");
3389 _termination_start_time_ms = os::elapsedVTime() * 1000.0;
3390
3391 // The G1CMTask class also extends the TerminatorTerminator class,
3392 // hence its should_exit_termination() method will also decide
3393 // whether to exit the termination protocol or not.
3394 bool finished = (is_serial ||
3395 _cm->terminator()->offer_termination(this));
3396 double termination_end_time_ms = os::elapsedVTime() * 1000.0;
3397 _termination_time_ms +=
3398 termination_end_time_ms - _termination_start_time_ms;
3399
3400 if (finished) {
3401 // We're all done.
3402
3403 if (_worker_id == 0) {
3404 // let's allow task 0 to do this
3405 if (concurrent()) {
3406 assert(_cm->concurrent_marking_in_progress(), "invariant");
3407 // we need to set this to false before the next
3408 // safepoint. This way we ensure that the marking phase
3409 // doesn't observe any more heap expansions.
3410 _cm->clear_concurrent_marking_in_progress();
3411 }
3412 }
3413
3414 // We can now guarantee that the global stack is empty, since
3415 // all other tasks have finished. We separated the guarantees so
3416 // that, if a condition is false, we can immediately find out
3417 // which one.
3418 guarantee(_cm->out_of_regions(), "only way to reach here");
3419 guarantee(_cm->mark_stack_empty(), "only way to reach here");
3420 guarantee(_task_queue->size() == 0, "only way to reach here");
3421 guarantee(!_cm->has_overflown(), "only way to reach here");
3422 guarantee(!_cm->mark_stack_overflow(), "only way to reach here");
3423 } else {
3424 // Apparently there's more work to do. Let's abort this task. It
3425 // will restart it and we can hopefully find more things to do.
3426 set_has_aborted();
3427 }
3428 }
3429
3430 // Mainly for debugging purposes to make sure that a pointer to the
3431 // closure which was statically allocated in this frame doesn't
3432 // escape it by accident.
3433 set_cm_oop_closure(NULL);
3434 double end_time_ms = os::elapsedVTime() * 1000.0;
3435 double elapsed_time_ms = end_time_ms - _start_time_ms;
3436 // Update the step history.
3437 _step_times_ms.add(elapsed_time_ms);
3438
3439 if (has_aborted()) {
3440 // The task was aborted for some reason.
3441 if (_has_timed_out) {
3442 double diff_ms = elapsed_time_ms - _time_target_ms;
3443 // Keep statistics of how well we did with respect to hitting
3444 // our target only if we actually timed out (if we aborted for
3445 // other reasons, then the results might get skewed).
3446 _marking_step_diffs_ms.add(diff_ms);
3447 }
3448
3449 if (_cm->has_overflown()) {
3450 // This is the interesting one. We aborted because a global
3451 // overflow was raised. This means we have to restart the
3452 // marking phase and start iterating over regions. However, in
3453 // order to do this we have to make sure that all tasks stop
3454 // what they are doing and re-initialize in a safe manner. We
3455 // will achieve this with the use of two barrier sync points.
3456
3457 if (!is_serial) {
3458 // We only need to enter the sync barrier if being called
3459 // from a parallel context
3460 _cm->enter_first_sync_barrier(_worker_id);
3461
3462 // When we exit this sync barrier we know that all tasks have
3463 // stopped doing marking work. So, it's now safe to
3464 // re-initialize our data structures. At the end of this method,
3465 // task 0 will clear the global data structures.
3466 }
3467
3468 // We clear the local state of this task...
3469 clear_region_fields();
3470
3471 if (!is_serial) {
3472 // ...and enter the second barrier.
3473 _cm->enter_second_sync_barrier(_worker_id);
3474 }
3475 // At this point, if we're during the concurrent phase of
3476 // marking, everything has been re-initialized and we're
3477 // ready to restart.
3478 }
3479 }
3480
3481 _claimed = false;
3482 }
3483
3484 G1CMTask::G1CMTask(uint worker_id,
3485 G1ConcurrentMark* cm,
3486 size_t* marked_bytes,
3487 BitMap* card_bm,
3488 G1CMTaskQueue* task_queue,
3489 G1CMTaskQueueSet* task_queues)
3490 : _g1h(G1CollectedHeap::heap()),
3491 _worker_id(worker_id), _cm(cm),
3492 _claimed(false),
3493 _nextMarkBitMap(NULL), _hash_seed(17),
3494 _task_queue(task_queue),
3495 _task_queues(task_queues),
3496 _cm_oop_closure(NULL),
3497 _marked_bytes_array(marked_bytes),
3498 _card_bm(card_bm) {
3499 guarantee(task_queue != NULL, "invariant");
3500 guarantee(task_queues != NULL, "invariant");
3501
3502 _marking_step_diffs_ms.add(0.5);
3503 }
3504
3505 // These are formatting macros that are used below to ensure
3506 // consistent formatting. The *_H_* versions are used to format the
3507 // header for a particular value and they should be kept consistent
3508 // with the corresponding macro. Also note that most of the macros add
3509 // the necessary white space (as a prefix) which makes them a bit
3510 // easier to compose.
3511
3512 // All the output lines are prefixed with this string to be able to
3513 // identify them easily in a large log file.
3514 #define G1PPRL_LINE_PREFIX "###"
3515
3516 #define G1PPRL_ADDR_BASE_FORMAT " " PTR_FORMAT "-" PTR_FORMAT
3517 #ifdef _LP64
3518 #define G1PPRL_ADDR_BASE_H_FORMAT " %37s"
3519 #else // _LP64
3520 #define G1PPRL_ADDR_BASE_H_FORMAT " %21s"
3521 #endif // _LP64
3522
3523 // For per-region info
3524 #define G1PPRL_TYPE_FORMAT " %-4s"
3525 #define G1PPRL_TYPE_H_FORMAT " %4s"
3526 #define G1PPRL_BYTE_FORMAT " " SIZE_FORMAT_W(9)
3527 #define G1PPRL_BYTE_H_FORMAT " %9s"
3528 #define G1PPRL_DOUBLE_FORMAT " %14.1f"
3529 #define G1PPRL_DOUBLE_H_FORMAT " %14s"
3530
3531 // For summary info
3532 #define G1PPRL_SUM_ADDR_FORMAT(tag) " " tag ":" G1PPRL_ADDR_BASE_FORMAT
3533 #define G1PPRL_SUM_BYTE_FORMAT(tag) " " tag ": " SIZE_FORMAT
3534 #define G1PPRL_SUM_MB_FORMAT(tag) " " tag ": %1.2f MB"
3535 #define G1PPRL_SUM_MB_PERC_FORMAT(tag) G1PPRL_SUM_MB_FORMAT(tag) " / %1.2f %%"
3536
3537 G1PrintRegionLivenessInfoClosure::
3538 G1PrintRegionLivenessInfoClosure(const char* phase_name)
3539 : _total_used_bytes(0), _total_capacity_bytes(0),
3540 _total_prev_live_bytes(0), _total_next_live_bytes(0),
3541 _hum_used_bytes(0), _hum_capacity_bytes(0),
3542 _hum_prev_live_bytes(0), _hum_next_live_bytes(0),
3543 _total_remset_bytes(0), _total_strong_code_roots_bytes(0) {
3544 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3545 MemRegion g1_reserved = g1h->g1_reserved();
3546 double now = os::elapsedTime();
3547
3548 // Print the header of the output.
3549 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX" PHASE %s @ %1.3f", phase_name, now);
3550 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX" HEAP"
3551 G1PPRL_SUM_ADDR_FORMAT("reserved")
3552 G1PPRL_SUM_BYTE_FORMAT("region-size"),
3553 p2i(g1_reserved.start()), p2i(g1_reserved.end()),
3554 HeapRegion::GrainBytes);
3555 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX);
3556 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX
3557 G1PPRL_TYPE_H_FORMAT
3558 G1PPRL_ADDR_BASE_H_FORMAT
3559 G1PPRL_BYTE_H_FORMAT
3560 G1PPRL_BYTE_H_FORMAT
3561 G1PPRL_BYTE_H_FORMAT
3562 G1PPRL_DOUBLE_H_FORMAT
3563 G1PPRL_BYTE_H_FORMAT
3564 G1PPRL_BYTE_H_FORMAT,
3565 "type", "address-range",
3566 "used", "prev-live", "next-live", "gc-eff",
3567 "remset", "code-roots");
3568 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX
3569 G1PPRL_TYPE_H_FORMAT
3570 G1PPRL_ADDR_BASE_H_FORMAT
3571 G1PPRL_BYTE_H_FORMAT
3572 G1PPRL_BYTE_H_FORMAT
3573 G1PPRL_BYTE_H_FORMAT
3574 G1PPRL_DOUBLE_H_FORMAT
3575 G1PPRL_BYTE_H_FORMAT
3576 G1PPRL_BYTE_H_FORMAT,
3577 "", "",
3578 "(bytes)", "(bytes)", "(bytes)", "(bytes/ms)",
3579 "(bytes)", "(bytes)");
3580 }
3581
3582 // It takes as a parameter a reference to one of the _hum_* fields, it
3583 // deduces the corresponding value for a region in a humongous region
3584 // series (either the region size, or what's left if the _hum_* field
3585 // is < the region size), and updates the _hum_* field accordingly.
3586 size_t G1PrintRegionLivenessInfoClosure::get_hum_bytes(size_t* hum_bytes) {
3587 size_t bytes = 0;
3588 // The > 0 check is to deal with the prev and next live bytes which
3589 // could be 0.
3590 if (*hum_bytes > 0) {
3591 bytes = MIN2(HeapRegion::GrainBytes, *hum_bytes);
3592 *hum_bytes -= bytes;
3593 }
3594 return bytes;
3595 }
3596
3597 // It deduces the values for a region in a humongous region series
3598 // from the _hum_* fields and updates those accordingly. It assumes
3599 // that that _hum_* fields have already been set up from the "starts
3600 // humongous" region and we visit the regions in address order.
3601 void G1PrintRegionLivenessInfoClosure::get_hum_bytes(size_t* used_bytes,
3602 size_t* capacity_bytes,
3603 size_t* prev_live_bytes,
3604 size_t* next_live_bytes) {
3605 assert(_hum_used_bytes > 0 && _hum_capacity_bytes > 0, "pre-condition");
3606 *used_bytes = get_hum_bytes(&_hum_used_bytes);
3607 *capacity_bytes = get_hum_bytes(&_hum_capacity_bytes);
3608 *prev_live_bytes = get_hum_bytes(&_hum_prev_live_bytes);
3609 *next_live_bytes = get_hum_bytes(&_hum_next_live_bytes);
3610 }
3611
3612 void G1PrintRegionLivenessInfoClosure::doHeapRegion(HeapRegion* r) {
3613 const char* type = r->get_type_str();
3614 HeapWord* bottom = r->bottom();
3615 HeapWord* end = r->end();
3616 size_t capacity_bytes = r->capacity();
3617 size_t used_bytes = r->used();
3618 size_t prev_live_bytes = r->live_bytes();
3619 size_t next_live_bytes = r->next_live_bytes();
3620 double gc_eff = r->gc_efficiency();
3621 size_t remset_bytes = r->rem_set()->mem_size();
3622 size_t strong_code_roots_bytes = r->rem_set()->strong_code_roots_mem_size();
3623
3624 if (r->is_starts_humongous()) {
3625 assert(_hum_used_bytes == 0 && _hum_capacity_bytes == 0 &&
3626 _hum_prev_live_bytes == 0 && _hum_next_live_bytes == 0,
3627 "they should have been zeroed after the last time we used them");
3628 // Set up the _hum_* fields.
3629 _hum_capacity_bytes = capacity_bytes;
3630 _hum_used_bytes = used_bytes;
3631 _hum_prev_live_bytes = prev_live_bytes;
3632 _hum_next_live_bytes = next_live_bytes;
3633 get_hum_bytes(&used_bytes, &capacity_bytes,
3634 &prev_live_bytes, &next_live_bytes);
3635 end = bottom + HeapRegion::GrainWords;
3636 } else if (r->is_continues_humongous()) {
3637 get_hum_bytes(&used_bytes, &capacity_bytes,
3638 &prev_live_bytes, &next_live_bytes);
3639 assert(end == bottom + HeapRegion::GrainWords, "invariant");
3640 }
3641
3642 _total_used_bytes += used_bytes;
3643 _total_capacity_bytes += capacity_bytes;
3644 _total_prev_live_bytes += prev_live_bytes;
3645 _total_next_live_bytes += next_live_bytes;
3646 _total_remset_bytes += remset_bytes;
3647 _total_strong_code_roots_bytes += strong_code_roots_bytes;
3648
3649 // Print a line for this particular region.
3650 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX
3651 G1PPRL_TYPE_FORMAT
3652 G1PPRL_ADDR_BASE_FORMAT
3653 G1PPRL_BYTE_FORMAT
3654 G1PPRL_BYTE_FORMAT
3655 G1PPRL_BYTE_FORMAT
3656 G1PPRL_DOUBLE_FORMAT
3657 G1PPRL_BYTE_FORMAT
3658 G1PPRL_BYTE_FORMAT,
3659 type, p2i(bottom), p2i(end),
3660 used_bytes, prev_live_bytes, next_live_bytes, gc_eff,
3661 remset_bytes, strong_code_roots_bytes);
3662 }
3663
3664 G1PrintRegionLivenessInfoClosure::~G1PrintRegionLivenessInfoClosure() {
3665 // add static memory usages to remembered set sizes
3666 _total_remset_bytes += HeapRegionRemSet::fl_mem_size() + HeapRegionRemSet::static_mem_size();
3667 // Print the footer of the output.
3668 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX);
3669 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX
3670 " SUMMARY"
3671 G1PPRL_SUM_MB_FORMAT("capacity")
3672 G1PPRL_SUM_MB_PERC_FORMAT("used")
3673 G1PPRL_SUM_MB_PERC_FORMAT("prev-live")
3674 G1PPRL_SUM_MB_PERC_FORMAT("next-live")
3675 G1PPRL_SUM_MB_FORMAT("remset")
3676 G1PPRL_SUM_MB_FORMAT("code-roots"),
3677 bytes_to_mb(_total_capacity_bytes),
3678 bytes_to_mb(_total_used_bytes),
3679 perc(_total_used_bytes, _total_capacity_bytes),
3680 bytes_to_mb(_total_prev_live_bytes),
3681 perc(_total_prev_live_bytes, _total_capacity_bytes),
3682 bytes_to_mb(_total_next_live_bytes),
3683 perc(_total_next_live_bytes, _total_capacity_bytes),
3684 bytes_to_mb(_total_remset_bytes),
3685 bytes_to_mb(_total_strong_code_roots_bytes));
3686 }