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 HeapRegionClosure {
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) : HeapRegionClosure(), _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 doHeapRegion(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 HeapRegionClosure {
730 G1CMBitMap* _bitmap;
731 bool _error;
732 public:
733 CheckBitmapClearHRClosure(G1CMBitMap* bitmap) : _bitmap(bitmap) {
734 }
735
736 virtual bool doHeapRegion(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 bool doHeapRegion(HeapRegion* r) {
755 r->note_start_of_marking();
756 return false;
757 }
758 };
759
760 void G1ConcurrentMark::checkpointRootsInitialPre() {
761 G1CollectedHeap* g1h = G1CollectedHeap::heap();
762 G1CollectorPolicy* g1p = g1h->g1_policy();
763
764 _has_aborted = false;
765
766 // Initialize marking structures. This has to be done in a STW phase.
767 reset();
768
769 // For each region note start of marking.
770 NoteStartOfMarkHRClosure startcl;
771 g1h->heap_region_iterate(&startcl);
772 }
773
774
775 void G1ConcurrentMark::checkpointRootsInitialPost() {
776 G1CollectedHeap* g1h = G1CollectedHeap::heap();
777
778 // Start Concurrent Marking weak-reference discovery.
779 ReferenceProcessor* rp = g1h->ref_processor_cm();
780 // enable ("weak") refs discovery
781 rp->enable_discovery();
782 rp->setup_policy(false); // snapshot the soft ref policy to be used in this cycle
783
784 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
785 // This is the start of the marking cycle, we're expected all
786 // threads to have SATB queues with active set to false.
787 satb_mq_set.set_active_all_threads(true, /* new active value */
788 false /* expected_active */);
789
790 _root_regions.prepare_for_scan();
791
792 // update_g1_committed() will be called at the end of an evac pause
793 // when marking is on. So, it's also called at the end of the
794 // initial-mark pause to update the heap end, if the heap expands
795 // during it. No need to call it here.
796 }
797
798 /*
799 * Notice that in the next two methods, we actually leave the STS
800 * during the barrier sync and join it immediately afterwards. If we
801 * do not do this, the following deadlock can occur: one thread could
802 * be in the barrier sync code, waiting for the other thread to also
803 * sync up, whereas another one could be trying to yield, while also
804 * waiting for the other threads to sync up too.
805 *
806 * Note, however, that this code is also used during remark and in
807 * this case we should not attempt to leave / enter the STS, otherwise
808 * we'll either hit an assert (debug / fastdebug) or deadlock
809 * (product). So we should only leave / enter the STS if we are
810 * operating concurrently.
811 *
812 * Because the thread that does the sync barrier has left the STS, it
813 * is possible to be suspended for a Full GC or an evacuation pause
814 * could occur. This is actually safe, since the entering the sync
815 * barrier is one of the last things do_marking_step() does, and it
816 * doesn't manipulate any data structures afterwards.
817 */
818
819 void G1ConcurrentMark::enter_first_sync_barrier(uint worker_id) {
820 bool barrier_aborted;
821 {
822 SuspendibleThreadSetLeaver sts_leave(concurrent());
823 barrier_aborted = !_first_overflow_barrier_sync.enter();
824 }
825
826 // at this point everyone should have synced up and not be doing any
827 // more work
828
829 if (barrier_aborted) {
830 // If the barrier aborted we ignore the overflow condition and
831 // just abort the whole marking phase as quickly as possible.
832 return;
833 }
834
835 // If we're executing the concurrent phase of marking, reset the marking
836 // state; otherwise the marking state is reset after reference processing,
837 // during the remark pause.
838 // If we reset here as a result of an overflow during the remark we will
839 // see assertion failures from any subsequent set_concurrency_and_phase()
840 // calls.
841 if (concurrent()) {
842 // let the task associated with with worker 0 do this
843 if (worker_id == 0) {
844 // task 0 is responsible for clearing the global data structures
845 // We should be here because of an overflow. During STW we should
846 // not clear the overflow flag since we rely on it being true when
847 // we exit this method to abort the pause and restart concurrent
848 // marking.
849 reset_marking_state(true /* clear_overflow */);
850
851 log_info(gc)("Concurrent Mark reset for overflow");
852 }
853 }
854
855 // after this, each task should reset its own data structures then
856 // then go into the second barrier
857 }
858
859 void G1ConcurrentMark::enter_second_sync_barrier(uint worker_id) {
860 SuspendibleThreadSetLeaver sts_leave(concurrent());
861 _second_overflow_barrier_sync.enter();
862
863 // at this point everything should be re-initialized and ready to go
864 }
865
866 class G1CMConcurrentMarkingTask: public AbstractGangTask {
867 private:
868 G1ConcurrentMark* _cm;
869 ConcurrentMarkThread* _cmt;
870
871 public:
872 void work(uint worker_id) {
873 assert(Thread::current()->is_ConcurrentGC_thread(),
874 "this should only be done by a conc GC thread");
875 ResourceMark rm;
876
877 double start_vtime = os::elapsedVTime();
878
879 {
880 SuspendibleThreadSetJoiner sts_join;
881
882 assert(worker_id < _cm->active_tasks(), "invariant");
883 G1CMTask* the_task = _cm->task(worker_id);
884 the_task->record_start_time();
885 if (!_cm->has_aborted()) {
886 do {
887 double start_vtime_sec = os::elapsedVTime();
888 double mark_step_duration_ms = G1ConcMarkStepDurationMillis;
889
890 the_task->do_marking_step(mark_step_duration_ms,
891 true /* do_termination */,
892 false /* is_serial*/);
893
894 double end_vtime_sec = os::elapsedVTime();
895 double elapsed_vtime_sec = end_vtime_sec - start_vtime_sec;
896 _cm->clear_has_overflown();
897
898 _cm->do_yield_check(worker_id);
899
900 jlong sleep_time_ms;
901 if (!_cm->has_aborted() && the_task->has_aborted()) {
902 sleep_time_ms =
903 (jlong) (elapsed_vtime_sec * _cm->sleep_factor() * 1000.0);
904 {
905 SuspendibleThreadSetLeaver sts_leave;
906 os::sleep(Thread::current(), sleep_time_ms, false);
907 }
908 }
909 } while (!_cm->has_aborted() && the_task->has_aborted());
910 }
911 the_task->record_end_time();
912 guarantee(!the_task->has_aborted() || _cm->has_aborted(), "invariant");
913 }
914
915 double end_vtime = os::elapsedVTime();
916 _cm->update_accum_task_vtime(worker_id, end_vtime - start_vtime);
917 }
918
919 G1CMConcurrentMarkingTask(G1ConcurrentMark* cm,
920 ConcurrentMarkThread* cmt) :
921 AbstractGangTask("Concurrent Mark"), _cm(cm), _cmt(cmt) { }
922
923 ~G1CMConcurrentMarkingTask() { }
924 };
925
926 // Calculates the number of active workers for a concurrent
927 // phase.
928 uint G1ConcurrentMark::calc_parallel_marking_threads() {
929 uint n_conc_workers = 0;
930 if (!UseDynamicNumberOfGCThreads ||
931 (!FLAG_IS_DEFAULT(ConcGCThreads) &&
932 !ForceDynamicNumberOfGCThreads)) {
933 n_conc_workers = max_parallel_marking_threads();
934 } else {
935 n_conc_workers =
936 AdaptiveSizePolicy::calc_default_active_workers(
937 max_parallel_marking_threads(),
938 1, /* Minimum workers */
939 parallel_marking_threads(),
940 Threads::number_of_non_daemon_threads());
941 // Don't scale down "n_conc_workers" by scale_parallel_threads() because
942 // that scaling has already gone into "_max_parallel_marking_threads".
943 }
944 assert(n_conc_workers > 0, "Always need at least 1");
945 return n_conc_workers;
946 }
947
948 void G1ConcurrentMark::scanRootRegion(HeapRegion* hr, uint worker_id) {
949 // Currently, only survivors can be root regions.
950 assert(hr->next_top_at_mark_start() == hr->bottom(), "invariant");
951 G1RootRegionScanClosure cl(_g1h, this, worker_id);
952
953 const uintx interval = PrefetchScanIntervalInBytes;
954 HeapWord* curr = hr->bottom();
955 const HeapWord* end = hr->top();
956 while (curr < end) {
957 Prefetch::read(curr, interval);
958 oop obj = oop(curr);
959 int size = obj->oop_iterate_size(&cl);
960 assert(size == obj->size(), "sanity");
961 curr += size;
962 }
963 }
964
965 class G1CMRootRegionScanTask : public AbstractGangTask {
966 private:
967 G1ConcurrentMark* _cm;
968
969 public:
970 G1CMRootRegionScanTask(G1ConcurrentMark* cm) :
971 AbstractGangTask("Root Region Scan"), _cm(cm) { }
972
973 void work(uint worker_id) {
974 assert(Thread::current()->is_ConcurrentGC_thread(),
975 "this should only be done by a conc GC thread");
976
977 G1CMRootRegions* root_regions = _cm->root_regions();
978 HeapRegion* hr = root_regions->claim_next();
979 while (hr != NULL) {
980 _cm->scanRootRegion(hr, worker_id);
981 hr = root_regions->claim_next();
982 }
983 }
984 };
985
986 void G1ConcurrentMark::scanRootRegions() {
987 // scan_in_progress() will have been set to true only if there was
988 // at least one root region to scan. So, if it's false, we
989 // should not attempt to do any further work.
990 if (root_regions()->scan_in_progress()) {
991 assert(!has_aborted(), "Aborting before root region scanning is finished not supported.");
992 GCTraceConcTime(Info, gc) tt("Concurrent Root Region Scan");
993
994 _parallel_marking_threads = calc_parallel_marking_threads();
995 assert(parallel_marking_threads() <= max_parallel_marking_threads(),
996 "Maximum number of marking threads exceeded");
997 uint active_workers = MAX2(1U, parallel_marking_threads());
998
999 G1CMRootRegionScanTask task(this);
1000 _parallel_workers->set_active_workers(active_workers);
1001 _parallel_workers->run_task(&task);
1002
1003 // It's possible that has_aborted() is true here without actually
1004 // aborting the survivor scan earlier. This is OK as it's
1005 // mainly used for sanity checking.
1006 root_regions()->scan_finished();
1007 }
1008 }
1009
1010 void G1ConcurrentMark::register_concurrent_phase_start(const char* title) {
1011 uint old_val = 0;
1012 do {
1013 old_val = Atomic::cmpxchg(ConcPhaseStarted, &_concurrent_phase_status, ConcPhaseNotStarted);
1014 } while (old_val != ConcPhaseNotStarted);
1015 _g1h->gc_timer_cm()->register_gc_concurrent_start(title);
1016 }
1017
1018 void G1ConcurrentMark::register_concurrent_phase_end_common(bool end_timer) {
1019 if (_concurrent_phase_status == ConcPhaseNotStarted) {
1020 return;
1021 }
1022
1023 uint old_val = Atomic::cmpxchg(ConcPhaseStopping, &_concurrent_phase_status, ConcPhaseStarted);
1024 if (old_val == ConcPhaseStarted) {
1025 _g1h->gc_timer_cm()->register_gc_concurrent_end();
1026 // If 'end_timer' is true, we came here to end timer which needs concurrent phase ended.
1027 // We need to end it before changing the status to 'ConcPhaseNotStarted' to prevent
1028 // starting a new concurrent phase by 'ConcurrentMarkThread'.
1029 if (end_timer) {
1030 _g1h->gc_timer_cm()->register_gc_end();
1031 }
1032 old_val = Atomic::cmpxchg(ConcPhaseNotStarted, &_concurrent_phase_status, ConcPhaseStopping);
1033 assert(old_val == ConcPhaseStopping, "Should not have changed since we entered this scope.");
1034 } else {
1035 do {
1036 // Let other thread finish changing '_concurrent_phase_status' to 'ConcPhaseNotStarted'.
1037 os::naked_short_sleep(1);
1038 } while (_concurrent_phase_status != ConcPhaseNotStarted);
1039 }
1040 }
1041
1042 void G1ConcurrentMark::register_concurrent_phase_end() {
1043 register_concurrent_phase_end_common(false);
1044 }
1045
1046 void G1ConcurrentMark::register_concurrent_gc_end_and_stop_timer() {
1047 register_concurrent_phase_end_common(true);
1048 }
1049
1050 void G1ConcurrentMark::markFromRoots() {
1051 // we might be tempted to assert that:
1052 // assert(asynch == !SafepointSynchronize::is_at_safepoint(),
1053 // "inconsistent argument?");
1054 // However that wouldn't be right, because it's possible that
1055 // a safepoint is indeed in progress as a younger generation
1056 // stop-the-world GC happens even as we mark in this generation.
1057
1058 _restart_for_overflow = false;
1059
1060 // _g1h has _n_par_threads
1061 _parallel_marking_threads = calc_parallel_marking_threads();
1062 assert(parallel_marking_threads() <= max_parallel_marking_threads(),
1063 "Maximum number of marking threads exceeded");
1064
1065 uint active_workers = MAX2(1U, parallel_marking_threads());
1066 assert(active_workers > 0, "Should have been set");
1067
1068 // Parallel task terminator is set in "set_concurrency_and_phase()"
1069 set_concurrency_and_phase(active_workers, true /* concurrent */);
1070
1071 G1CMConcurrentMarkingTask markingTask(this, cmThread());
1072 _parallel_workers->set_active_workers(active_workers);
1073 _parallel_workers->run_task(&markingTask);
1074 print_stats();
1075 }
1076
1077 void G1ConcurrentMark::checkpointRootsFinal(bool clear_all_soft_refs) {
1078 // world is stopped at this checkpoint
1079 assert(SafepointSynchronize::is_at_safepoint(),
1080 "world should be stopped");
1081
1082 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1083
1084 // If a full collection has happened, we shouldn't do this.
1085 if (has_aborted()) {
1086 g1h->collector_state()->set_mark_in_progress(false); // So bitmap clearing isn't confused
1087 return;
1088 }
1089
1090 if (VerifyDuringGC) {
1091 HandleMark hm; // handle scope
1092 g1h->prepare_for_verify();
1093 Universe::verify(VerifyOption_G1UsePrevMarking, "During GC (before)");
1094 }
1095 g1h->verifier()->check_bitmaps("Remark Start");
1096
1097 G1CollectorPolicy* g1p = g1h->g1_policy();
1098 g1p->record_concurrent_mark_remark_start();
1099
1100 double start = os::elapsedTime();
1101
1102 checkpointRootsFinalWork();
1103
1104 double mark_work_end = os::elapsedTime();
1105
1106 weakRefsWork(clear_all_soft_refs);
1107
1108 if (has_overflown()) {
1109 // Oops. We overflowed. Restart concurrent marking.
1110 _restart_for_overflow = true;
1111 log_develop_trace(gc)("Remark led to restart for overflow.");
1112
1113 // Verify the heap w.r.t. the previous marking bitmap.
1114 if (VerifyDuringGC) {
1115 HandleMark hm; // handle scope
1116 g1h->prepare_for_verify();
1117 Universe::verify(VerifyOption_G1UsePrevMarking, "During GC (overflow)");
1118 }
1119
1120 // Clear the marking state because we will be restarting
1121 // marking due to overflowing the global mark stack.
1122 reset_marking_state();
1123 } else {
1124 {
1125 GCTraceTime(Debug, gc) trace("Aggregate Data", g1h->gc_timer_cm());
1126
1127 // Aggregate the per-task counting data that we have accumulated
1128 // while marking.
1129 aggregate_count_data();
1130 }
1131
1132 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
1133 // We're done with marking.
1134 // This is the end of the marking cycle, we're expected all
1135 // threads to have SATB queues with active set to true.
1136 satb_mq_set.set_active_all_threads(false, /* new active value */
1137 true /* expected_active */);
1138
1139 if (VerifyDuringGC) {
1140 HandleMark hm; // handle scope
1141 g1h->prepare_for_verify();
1142 Universe::verify(VerifyOption_G1UseNextMarking, "During GC (after)");
1143 }
1144 g1h->verifier()->check_bitmaps("Remark End");
1145 assert(!restart_for_overflow(), "sanity");
1146 // Completely reset the marking state since marking completed
1147 set_non_marking_state();
1148 }
1149
1150 // Expand the marking stack, if we have to and if we can.
1151 if (_markStack.should_expand()) {
1152 _markStack.expand();
1153 }
1154
1155 // Statistics
1156 double now = os::elapsedTime();
1157 _remark_mark_times.add((mark_work_end - start) * 1000.0);
1158 _remark_weak_ref_times.add((now - mark_work_end) * 1000.0);
1159 _remark_times.add((now - start) * 1000.0);
1160
1161 g1p->record_concurrent_mark_remark_end();
1162
1163 G1CMIsAliveClosure is_alive(g1h);
1164 g1h->gc_tracer_cm()->report_object_count_after_gc(&is_alive);
1165 }
1166
1167 // Base class of the closures that finalize and verify the
1168 // liveness counting data.
1169 class G1CMCountDataClosureBase: public HeapRegionClosure {
1170 protected:
1171 G1CollectedHeap* _g1h;
1172 G1ConcurrentMark* _cm;
1173 CardTableModRefBS* _ct_bs;
1174
1175 BitMap* _region_bm;
1176 BitMap* _card_bm;
1177
1178 // Takes a region that's not empty (i.e., it has at least one
1179 // live object in it and sets its corresponding bit on the region
1180 // bitmap to 1.
1181 void set_bit_for_region(HeapRegion* hr) {
1182 BitMap::idx_t index = (BitMap::idx_t) hr->hrm_index();
1183 _region_bm->par_at_put(index, true);
1184 }
1185
1186 public:
1187 G1CMCountDataClosureBase(G1CollectedHeap* g1h,
1188 BitMap* region_bm, BitMap* card_bm):
1189 _g1h(g1h), _cm(g1h->concurrent_mark()),
1190 _ct_bs(barrier_set_cast<CardTableModRefBS>(g1h->barrier_set())),
1191 _region_bm(region_bm), _card_bm(card_bm) { }
1192 };
1193
1194 // Closure that calculates the # live objects per region. Used
1195 // for verification purposes during the cleanup pause.
1196 class CalcLiveObjectsClosure: public G1CMCountDataClosureBase {
1197 G1CMBitMapRO* _bm;
1198 size_t _region_marked_bytes;
1199
1200 public:
1201 CalcLiveObjectsClosure(G1CMBitMapRO *bm, G1CollectedHeap* g1h,
1202 BitMap* region_bm, BitMap* card_bm) :
1203 G1CMCountDataClosureBase(g1h, region_bm, card_bm),
1204 _bm(bm), _region_marked_bytes(0) { }
1205
1206 bool doHeapRegion(HeapRegion* hr) {
1207 HeapWord* ntams = hr->next_top_at_mark_start();
1208 HeapWord* start = hr->bottom();
1209
1210 assert(start <= hr->end() && start <= ntams && ntams <= hr->end(),
1211 "Preconditions not met - "
1212 "start: " PTR_FORMAT ", ntams: " PTR_FORMAT ", end: " PTR_FORMAT,
1213 p2i(start), p2i(ntams), p2i(hr->end()));
1214
1215 // Find the first marked object at or after "start".
1216 start = _bm->getNextMarkedWordAddress(start, ntams);
1217
1218 size_t marked_bytes = 0;
1219
1220 while (start < ntams) {
1221 oop obj = oop(start);
1222 int obj_sz = obj->size();
1223 HeapWord* obj_end = start + obj_sz;
1224
1225 BitMap::idx_t start_idx = _cm->card_bitmap_index_for(start);
1226 BitMap::idx_t end_idx = _cm->card_bitmap_index_for(obj_end);
1227
1228 // Note: if we're looking at the last region in heap - obj_end
1229 // could be actually just beyond the end of the heap; end_idx
1230 // will then correspond to a (non-existent) card that is also
1231 // just beyond the heap.
1232 if (_g1h->is_in_g1_reserved(obj_end) && !_ct_bs->is_card_aligned(obj_end)) {
1233 // end of object is not card aligned - increment to cover
1234 // all the cards spanned by the object
1235 end_idx += 1;
1236 }
1237
1238 // Set the bits in the card BM for the cards spanned by this object.
1239 _cm->set_card_bitmap_range(_card_bm, start_idx, end_idx, true /* is_par */);
1240
1241 // Add the size of this object to the number of marked bytes.
1242 marked_bytes += (size_t)obj_sz * HeapWordSize;
1243
1244 // This will happen if we are handling a humongous object that spans
1245 // several heap regions.
1246 if (obj_end > hr->end()) {
1247 break;
1248 }
1249 // Find the next marked object after this one.
1250 start = _bm->getNextMarkedWordAddress(obj_end, ntams);
1251 }
1252
1253 // Mark the allocated-since-marking portion...
1254 HeapWord* top = hr->top();
1255 if (ntams < top) {
1256 BitMap::idx_t start_idx = _cm->card_bitmap_index_for(ntams);
1257 BitMap::idx_t end_idx = _cm->card_bitmap_index_for(top);
1258
1259 // Note: if we're looking at the last region in heap - top
1260 // could be actually just beyond the end of the heap; end_idx
1261 // will then correspond to a (non-existent) card that is also
1262 // just beyond the heap.
1263 if (_g1h->is_in_g1_reserved(top) && !_ct_bs->is_card_aligned(top)) {
1264 // end of object is not card aligned - increment to cover
1265 // all the cards spanned by the object
1266 end_idx += 1;
1267 }
1268 _cm->set_card_bitmap_range(_card_bm, start_idx, end_idx, true /* is_par */);
1269
1270 // This definitely means the region has live objects.
1271 set_bit_for_region(hr);
1272 }
1273
1274 // Update the live region bitmap.
1275 if (marked_bytes > 0) {
1276 set_bit_for_region(hr);
1277 }
1278
1279 // Set the marked bytes for the current region so that
1280 // it can be queried by a calling verification routine
1281 _region_marked_bytes = marked_bytes;
1282
1283 return false;
1284 }
1285
1286 size_t region_marked_bytes() const { return _region_marked_bytes; }
1287 };
1288
1289 // Heap region closure used for verifying the counting data
1290 // that was accumulated concurrently and aggregated during
1291 // the remark pause. This closure is applied to the heap
1292 // regions during the STW cleanup pause.
1293
1294 class VerifyLiveObjectDataHRClosure: public HeapRegionClosure {
1295 G1CollectedHeap* _g1h;
1296 G1ConcurrentMark* _cm;
1297 CalcLiveObjectsClosure _calc_cl;
1298 BitMap* _region_bm; // Region BM to be verified
1299 BitMap* _card_bm; // Card BM to be verified
1300
1301 BitMap* _exp_region_bm; // Expected Region BM values
1302 BitMap* _exp_card_bm; // Expected card BM values
1303
1304 int _failures;
1305
1306 public:
1307 VerifyLiveObjectDataHRClosure(G1CollectedHeap* g1h,
1308 BitMap* region_bm,
1309 BitMap* card_bm,
1310 BitMap* exp_region_bm,
1311 BitMap* exp_card_bm) :
1312 _g1h(g1h), _cm(g1h->concurrent_mark()),
1313 _calc_cl(_cm->nextMarkBitMap(), g1h, exp_region_bm, exp_card_bm),
1314 _region_bm(region_bm), _card_bm(card_bm),
1315 _exp_region_bm(exp_region_bm), _exp_card_bm(exp_card_bm),
1316 _failures(0) { }
1317
1318 int failures() const { return _failures; }
1319
1320 bool doHeapRegion(HeapRegion* hr) {
1321 int failures = 0;
1322
1323 // Call the CalcLiveObjectsClosure to walk the marking bitmap for
1324 // this region and set the corresponding bits in the expected region
1325 // and card bitmaps.
1326 bool res = _calc_cl.doHeapRegion(hr);
1327 assert(res == false, "should be continuing");
1328
1329 // Verify the marked bytes for this region.
1330 size_t exp_marked_bytes = _calc_cl.region_marked_bytes();
1331 size_t act_marked_bytes = hr->next_marked_bytes();
1332
1333 if (exp_marked_bytes > act_marked_bytes) {
1334 if (hr->is_starts_humongous()) {
1335 // For start_humongous regions, the size of the whole object will be
1336 // in exp_marked_bytes.
1337 HeapRegion* region = hr;
1338 int num_regions;
1339 for (num_regions = 0; region != NULL; num_regions++) {
1340 region = _g1h->next_region_in_humongous(region);
1341 }
1342 if ((num_regions-1) * HeapRegion::GrainBytes >= exp_marked_bytes) {
1343 failures += 1;
1344 } else if (num_regions * HeapRegion::GrainBytes < exp_marked_bytes) {
1345 failures += 1;
1346 }
1347 } else {
1348 // We're not OK if expected marked bytes > actual marked bytes. It means
1349 // we have missed accounting some objects during the actual marking.
1350 failures += 1;
1351 }
1352 }
1353
1354 // Verify the bit, for this region, in the actual and expected
1355 // (which was just calculated) region bit maps.
1356 // We're not OK if the bit in the calculated expected region
1357 // bitmap is set and the bit in the actual region bitmap is not.
1358 BitMap::idx_t index = (BitMap::idx_t) hr->hrm_index();
1359
1360 bool expected = _exp_region_bm->at(index);
1361 bool actual = _region_bm->at(index);
1362 if (expected && !actual) {
1363 failures += 1;
1364 }
1365
1366 // Verify that the card bit maps for the cards spanned by the current
1367 // region match. We have an error if we have a set bit in the expected
1368 // bit map and the corresponding bit in the actual bitmap is not set.
1369
1370 BitMap::idx_t start_idx = _cm->card_bitmap_index_for(hr->bottom());
1371 BitMap::idx_t end_idx = _cm->card_bitmap_index_for(hr->top());
1372
1373 for (BitMap::idx_t i = start_idx; i < end_idx; i+=1) {
1374 expected = _exp_card_bm->at(i);
1375 actual = _card_bm->at(i);
1376
1377 if (expected && !actual) {
1378 failures += 1;
1379 }
1380 }
1381
1382 _failures += failures;
1383
1384 // We could stop iteration over the heap when we
1385 // find the first violating region by returning true.
1386 return false;
1387 }
1388 };
1389
1390 class G1ParVerifyFinalCountTask: public AbstractGangTask {
1391 protected:
1392 G1CollectedHeap* _g1h;
1393 G1ConcurrentMark* _cm;
1394 BitMap* _actual_region_bm;
1395 BitMap* _actual_card_bm;
1396
1397 uint _n_workers;
1398
1399 BitMap* _expected_region_bm;
1400 BitMap* _expected_card_bm;
1401
1402 int _failures;
1403
1404 HeapRegionClaimer _hrclaimer;
1405
1406 public:
1407 G1ParVerifyFinalCountTask(G1CollectedHeap* g1h,
1408 BitMap* region_bm, BitMap* card_bm,
1409 BitMap* expected_region_bm, BitMap* expected_card_bm)
1410 : AbstractGangTask("G1 verify final counting"),
1411 _g1h(g1h), _cm(_g1h->concurrent_mark()),
1412 _actual_region_bm(region_bm), _actual_card_bm(card_bm),
1413 _expected_region_bm(expected_region_bm), _expected_card_bm(expected_card_bm),
1414 _failures(0),
1415 _n_workers(_g1h->workers()->active_workers()), _hrclaimer(_n_workers) {
1416 assert(VerifyDuringGC, "don't call this otherwise");
1417 assert(_expected_card_bm->size() == _actual_card_bm->size(), "sanity");
1418 assert(_expected_region_bm->size() == _actual_region_bm->size(), "sanity");
1419 }
1420
1421 void work(uint worker_id) {
1422 assert(worker_id < _n_workers, "invariant");
1423
1424 VerifyLiveObjectDataHRClosure verify_cl(_g1h,
1425 _actual_region_bm, _actual_card_bm,
1426 _expected_region_bm,
1427 _expected_card_bm);
1428
1429 _g1h->heap_region_par_iterate(&verify_cl, worker_id, &_hrclaimer);
1430
1431 Atomic::add(verify_cl.failures(), &_failures);
1432 }
1433
1434 int failures() const { return _failures; }
1435 };
1436
1437 // Closure that finalizes the liveness counting data.
1438 // Used during the cleanup pause.
1439 // Sets the bits corresponding to the interval [NTAMS, top]
1440 // (which contains the implicitly live objects) in the
1441 // card liveness bitmap. Also sets the bit for each region,
1442 // containing live data, in the region liveness bitmap.
1443
1444 class FinalCountDataUpdateClosure: public G1CMCountDataClosureBase {
1445 public:
1446 FinalCountDataUpdateClosure(G1CollectedHeap* g1h,
1447 BitMap* region_bm,
1448 BitMap* card_bm) :
1449 G1CMCountDataClosureBase(g1h, region_bm, card_bm) { }
1450
1451 bool doHeapRegion(HeapRegion* hr) {
1452 HeapWord* ntams = hr->next_top_at_mark_start();
1453 HeapWord* top = hr->top();
1454
1455 assert(hr->bottom() <= ntams && ntams <= hr->end(), "Preconditions.");
1456
1457 // Mark the allocated-since-marking portion...
1458 if (ntams < top) {
1459 // This definitely means the region has live objects.
1460 set_bit_for_region(hr);
1461
1462 // Now set the bits in the card bitmap for [ntams, top)
1463 BitMap::idx_t start_idx = _cm->card_bitmap_index_for(ntams);
1464 BitMap::idx_t end_idx = _cm->card_bitmap_index_for(top);
1465
1466 // Note: if we're looking at the last region in heap - top
1467 // could be actually just beyond the end of the heap; end_idx
1468 // will then correspond to a (non-existent) card that is also
1469 // just beyond the heap.
1470 if (_g1h->is_in_g1_reserved(top) && !_ct_bs->is_card_aligned(top)) {
1471 // end of object is not card aligned - increment to cover
1472 // all the cards spanned by the object
1473 end_idx += 1;
1474 }
1475
1476 assert(end_idx <= _card_bm->size(),
1477 "oob: end_idx= " SIZE_FORMAT ", bitmap size= " SIZE_FORMAT,
1478 end_idx, _card_bm->size());
1479 assert(start_idx < _card_bm->size(),
1480 "oob: start_idx= " SIZE_FORMAT ", bitmap size= " SIZE_FORMAT,
1481 start_idx, _card_bm->size());
1482
1483 _cm->set_card_bitmap_range(_card_bm, start_idx, end_idx, true /* is_par */);
1484 }
1485
1486 // Set the bit for the region if it contains live data
1487 if (hr->next_marked_bytes() > 0) {
1488 set_bit_for_region(hr);
1489 }
1490
1491 return false;
1492 }
1493 };
1494
1495 class G1ParFinalCountTask: public AbstractGangTask {
1496 protected:
1497 G1CollectedHeap* _g1h;
1498 G1ConcurrentMark* _cm;
1499 BitMap* _actual_region_bm;
1500 BitMap* _actual_card_bm;
1501
1502 uint _n_workers;
1503 HeapRegionClaimer _hrclaimer;
1504
1505 public:
1506 G1ParFinalCountTask(G1CollectedHeap* g1h, BitMap* region_bm, BitMap* card_bm)
1507 : AbstractGangTask("G1 final counting"),
1508 _g1h(g1h), _cm(_g1h->concurrent_mark()),
1509 _actual_region_bm(region_bm), _actual_card_bm(card_bm),
1510 _n_workers(_g1h->workers()->active_workers()), _hrclaimer(_n_workers) {
1511 }
1512
1513 void work(uint worker_id) {
1514 assert(worker_id < _n_workers, "invariant");
1515
1516 FinalCountDataUpdateClosure final_update_cl(_g1h,
1517 _actual_region_bm,
1518 _actual_card_bm);
1519
1520 _g1h->heap_region_par_iterate(&final_update_cl, worker_id, &_hrclaimer);
1521 }
1522 };
1523
1524 class G1NoteEndOfConcMarkClosure : public HeapRegionClosure {
1525 G1CollectedHeap* _g1;
1526 size_t _freed_bytes;
1527 FreeRegionList* _local_cleanup_list;
1528 uint _old_regions_removed;
1529 uint _humongous_regions_removed;
1530 HRRSCleanupTask* _hrrs_cleanup_task;
1531
1532 public:
1533 G1NoteEndOfConcMarkClosure(G1CollectedHeap* g1,
1534 FreeRegionList* local_cleanup_list,
1535 HRRSCleanupTask* hrrs_cleanup_task) :
1536 _g1(g1),
1537 _freed_bytes(0),
1538 _local_cleanup_list(local_cleanup_list),
1539 _old_regions_removed(0),
1540 _humongous_regions_removed(0),
1541 _hrrs_cleanup_task(hrrs_cleanup_task) { }
1542
1543 size_t freed_bytes() { return _freed_bytes; }
1544 const uint old_regions_removed() { return _old_regions_removed; }
1545 const uint humongous_regions_removed() { return _humongous_regions_removed; }
1546
1547 bool doHeapRegion(HeapRegion *hr) {
1548 if (hr->is_archive()) {
1549 return false;
1550 }
1551 // We use a claim value of zero here because all regions
1552 // were claimed with value 1 in the FinalCount task.
1553 _g1->reset_gc_time_stamps(hr);
1554 hr->note_end_of_marking();
1555
1556 if (hr->used() > 0 && hr->max_live_bytes() == 0 && !hr->is_young()) {
1557 _freed_bytes += hr->used();
1558 hr->set_containing_set(NULL);
1559 if (hr->is_humongous()) {
1560 _humongous_regions_removed++;
1561 _g1->free_humongous_region(hr, _local_cleanup_list, true);
1562 } else {
1563 _old_regions_removed++;
1564 _g1->free_region(hr, _local_cleanup_list, true);
1565 }
1566 } else {
1567 hr->rem_set()->do_cleanup_work(_hrrs_cleanup_task);
1568 }
1569
1570 return false;
1571 }
1572 };
1573
1574 class G1ParNoteEndTask: public AbstractGangTask {
1575 friend class G1NoteEndOfConcMarkClosure;
1576
1577 protected:
1578 G1CollectedHeap* _g1h;
1579 FreeRegionList* _cleanup_list;
1580 HeapRegionClaimer _hrclaimer;
1581
1582 public:
1583 G1ParNoteEndTask(G1CollectedHeap* g1h, FreeRegionList* cleanup_list, uint n_workers) :
1584 AbstractGangTask("G1 note end"), _g1h(g1h), _cleanup_list(cleanup_list), _hrclaimer(n_workers) {
1585 }
1586
1587 void work(uint worker_id) {
1588 FreeRegionList local_cleanup_list("Local Cleanup List");
1589 HRRSCleanupTask hrrs_cleanup_task;
1590 G1NoteEndOfConcMarkClosure g1_note_end(_g1h, &local_cleanup_list,
1591 &hrrs_cleanup_task);
1592 _g1h->heap_region_par_iterate(&g1_note_end, worker_id, &_hrclaimer);
1593 assert(g1_note_end.complete(), "Shouldn't have yielded!");
1594
1595 // Now update the lists
1596 _g1h->remove_from_old_sets(g1_note_end.old_regions_removed(), g1_note_end.humongous_regions_removed());
1597 {
1598 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
1599 _g1h->decrement_summary_bytes(g1_note_end.freed_bytes());
1600
1601 // If we iterate over the global cleanup list at the end of
1602 // cleanup to do this printing we will not guarantee to only
1603 // generate output for the newly-reclaimed regions (the list
1604 // might not be empty at the beginning of cleanup; we might
1605 // still be working on its previous contents). So we do the
1606 // printing here, before we append the new regions to the global
1607 // cleanup list.
1608
1609 G1HRPrinter* hr_printer = _g1h->hr_printer();
1610 if (hr_printer->is_active()) {
1611 FreeRegionListIterator iter(&local_cleanup_list);
1612 while (iter.more_available()) {
1613 HeapRegion* hr = iter.get_next();
1614 hr_printer->cleanup(hr);
1615 }
1616 }
1617
1618 _cleanup_list->add_ordered(&local_cleanup_list);
1619 assert(local_cleanup_list.is_empty(), "post-condition");
1620
1621 HeapRegionRemSet::finish_cleanup_task(&hrrs_cleanup_task);
1622 }
1623 }
1624 };
1625
1626 void G1ConcurrentMark::cleanup() {
1627 // world is stopped at this checkpoint
1628 assert(SafepointSynchronize::is_at_safepoint(),
1629 "world should be stopped");
1630 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1631
1632 // If a full collection has happened, we shouldn't do this.
1633 if (has_aborted()) {
1634 g1h->collector_state()->set_mark_in_progress(false); // So bitmap clearing isn't confused
1635 return;
1636 }
1637
1638 g1h->verifier()->verify_region_sets_optional();
1639
1640 if (VerifyDuringGC) {
1641 HandleMark hm; // handle scope
1642 g1h->prepare_for_verify();
1643 Universe::verify(VerifyOption_G1UsePrevMarking, "During GC (before)");
1644 }
1645 g1h->verifier()->check_bitmaps("Cleanup Start");
1646
1647 G1CollectorPolicy* g1p = g1h->g1_policy();
1648 g1p->record_concurrent_mark_cleanup_start();
1649
1650 double start = os::elapsedTime();
1651
1652 HeapRegionRemSet::reset_for_cleanup_tasks();
1653
1654 // Do counting once more with the world stopped for good measure.
1655 G1ParFinalCountTask g1_par_count_task(g1h, &_region_bm, &_card_bm);
1656
1657 g1h->workers()->run_task(&g1_par_count_task);
1658
1659 if (VerifyDuringGC) {
1660 // Verify that the counting data accumulated during marking matches
1661 // that calculated by walking the marking bitmap.
1662
1663 // Bitmaps to hold expected values
1664 BitMap expected_region_bm(_region_bm.size(), true);
1665 BitMap expected_card_bm(_card_bm.size(), true);
1666
1667 G1ParVerifyFinalCountTask g1_par_verify_task(g1h,
1668 &_region_bm,
1669 &_card_bm,
1670 &expected_region_bm,
1671 &expected_card_bm);
1672
1673 g1h->workers()->run_task(&g1_par_verify_task);
1674
1675 guarantee(g1_par_verify_task.failures() == 0, "Unexpected accounting failures");
1676 }
1677
1678 size_t start_used_bytes = g1h->used();
1679 g1h->collector_state()->set_mark_in_progress(false);
1680
1681 double count_end = os::elapsedTime();
1682 double this_final_counting_time = (count_end - start);
1683 _total_counting_time += this_final_counting_time;
1684
1685 if (log_is_enabled(Trace, gc, liveness)) {
1686 G1PrintRegionLivenessInfoClosure cl("Post-Marking");
1687 _g1h->heap_region_iterate(&cl);
1688 }
1689
1690 // Install newly created mark bitMap as "prev".
1691 swapMarkBitMaps();
1692
1693 g1h->reset_gc_time_stamp();
1694
1695 uint n_workers = _g1h->workers()->active_workers();
1696
1697 // Note end of marking in all heap regions.
1698 G1ParNoteEndTask g1_par_note_end_task(g1h, &_cleanup_list, n_workers);
1699 g1h->workers()->run_task(&g1_par_note_end_task);
1700 g1h->check_gc_time_stamps();
1701
1702 if (!cleanup_list_is_empty()) {
1703 // The cleanup list is not empty, so we'll have to process it
1704 // concurrently. Notify anyone else that might be wanting free
1705 // regions that there will be more free regions coming soon.
1706 g1h->set_free_regions_coming();
1707 }
1708
1709 // call below, since it affects the metric by which we sort the heap
1710 // regions.
1711 if (G1ScrubRemSets) {
1712 double rs_scrub_start = os::elapsedTime();
1713 g1h->scrub_rem_set(&_region_bm, &_card_bm);
1714 _total_rs_scrub_time += (os::elapsedTime() - rs_scrub_start);
1715 }
1716
1717 // this will also free any regions totally full of garbage objects,
1718 // and sort the regions.
1719 g1h->g1_policy()->record_concurrent_mark_cleanup_end();
1720
1721 // Statistics.
1722 double end = os::elapsedTime();
1723 _cleanup_times.add((end - start) * 1000.0);
1724
1725 // Clean up will have freed any regions completely full of garbage.
1726 // Update the soft reference policy with the new heap occupancy.
1727 Universe::update_heap_info_at_gc();
1728
1729 if (VerifyDuringGC) {
1730 HandleMark hm; // handle scope
1731 g1h->prepare_for_verify();
1732 Universe::verify(VerifyOption_G1UsePrevMarking, "During GC (after)");
1733 }
1734
1735 g1h->verifier()->check_bitmaps("Cleanup End");
1736
1737 g1h->verifier()->verify_region_sets_optional();
1738
1739 // We need to make this be a "collection" so any collection pause that
1740 // races with it goes around and waits for completeCleanup to finish.
1741 g1h->increment_total_collections();
1742
1743 // Clean out dead classes and update Metaspace sizes.
1744 if (ClassUnloadingWithConcurrentMark) {
1745 ClassLoaderDataGraph::purge();
1746 }
1747 MetaspaceGC::compute_new_size();
1748
1749 // We reclaimed old regions so we should calculate the sizes to make
1750 // sure we update the old gen/space data.
1751 g1h->g1mm()->update_sizes();
1752 g1h->allocation_context_stats().update_after_mark();
1753
1754 g1h->trace_heap_after_concurrent_cycle();
1755 }
1756
1757 void G1ConcurrentMark::completeCleanup() {
1758 if (has_aborted()) return;
1759
1760 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1761
1762 _cleanup_list.verify_optional();
1763 FreeRegionList tmp_free_list("Tmp Free List");
1764
1765 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [complete cleanup] : "
1766 "cleanup list has %u entries",
1767 _cleanup_list.length());
1768
1769 // No one else should be accessing the _cleanup_list at this point,
1770 // so it is not necessary to take any locks
1771 while (!_cleanup_list.is_empty()) {
1772 HeapRegion* hr = _cleanup_list.remove_region(true /* from_head */);
1773 assert(hr != NULL, "Got NULL from a non-empty list");
1774 hr->par_clear();
1775 tmp_free_list.add_ordered(hr);
1776
1777 // Instead of adding one region at a time to the secondary_free_list,
1778 // we accumulate them in the local list and move them a few at a
1779 // time. This also cuts down on the number of notify_all() calls
1780 // we do during this process. We'll also append the local list when
1781 // _cleanup_list is empty (which means we just removed the last
1782 // region from the _cleanup_list).
1783 if ((tmp_free_list.length() % G1SecondaryFreeListAppendLength == 0) ||
1784 _cleanup_list.is_empty()) {
1785 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [complete cleanup] : "
1786 "appending %u entries to the secondary_free_list, "
1787 "cleanup list still has %u entries",
1788 tmp_free_list.length(),
1789 _cleanup_list.length());
1790
1791 {
1792 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
1793 g1h->secondary_free_list_add(&tmp_free_list);
1794 SecondaryFreeList_lock->notify_all();
1795 }
1796 #ifndef PRODUCT
1797 if (G1StressConcRegionFreeing) {
1798 for (uintx i = 0; i < G1StressConcRegionFreeingDelayMillis; ++i) {
1799 os::sleep(Thread::current(), (jlong) 1, false);
1800 }
1801 }
1802 #endif
1803 }
1804 }
1805 assert(tmp_free_list.is_empty(), "post-condition");
1806 }
1807
1808 // Supporting Object and Oop closures for reference discovery
1809 // and processing in during marking
1810
1811 bool G1CMIsAliveClosure::do_object_b(oop obj) {
1812 HeapWord* addr = (HeapWord*)obj;
1813 return addr != NULL &&
1814 (!_g1->is_in_g1_reserved(addr) || !_g1->is_obj_ill(obj));
1815 }
1816
1817 // 'Keep Alive' oop closure used by both serial parallel reference processing.
1818 // Uses the G1CMTask associated with a worker thread (for serial reference
1819 // processing the G1CMTask for worker 0 is used) to preserve (mark) and
1820 // trace referent objects.
1821 //
1822 // Using the G1CMTask and embedded local queues avoids having the worker
1823 // threads operating on the global mark stack. This reduces the risk
1824 // of overflowing the stack - which we would rather avoid at this late
1825 // state. Also using the tasks' local queues removes the potential
1826 // of the workers interfering with each other that could occur if
1827 // operating on the global stack.
1828
1829 class G1CMKeepAliveAndDrainClosure: public OopClosure {
1830 G1ConcurrentMark* _cm;
1831 G1CMTask* _task;
1832 int _ref_counter_limit;
1833 int _ref_counter;
1834 bool _is_serial;
1835 public:
1836 G1CMKeepAliveAndDrainClosure(G1ConcurrentMark* cm, G1CMTask* task, bool is_serial) :
1837 _cm(cm), _task(task), _is_serial(is_serial),
1838 _ref_counter_limit(G1RefProcDrainInterval) {
1839 assert(_ref_counter_limit > 0, "sanity");
1840 assert(!_is_serial || _task->worker_id() == 0, "only task 0 for serial code");
1841 _ref_counter = _ref_counter_limit;
1842 }
1843
1844 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
1845 virtual void do_oop( oop* p) { do_oop_work(p); }
1846
1847 template <class T> void do_oop_work(T* p) {
1848 if (!_cm->has_overflown()) {
1849 oop obj = oopDesc::load_decode_heap_oop(p);
1850 _task->deal_with_reference(obj);
1851 _ref_counter--;
1852
1853 if (_ref_counter == 0) {
1854 // We have dealt with _ref_counter_limit references, pushing them
1855 // and objects reachable from them on to the local stack (and
1856 // possibly the global stack). Call G1CMTask::do_marking_step() to
1857 // process these entries.
1858 //
1859 // We call G1CMTask::do_marking_step() in a loop, which we'll exit if
1860 // there's nothing more to do (i.e. we're done with the entries that
1861 // were pushed as a result of the G1CMTask::deal_with_reference() calls
1862 // above) or we overflow.
1863 //
1864 // Note: G1CMTask::do_marking_step() can set the G1CMTask::has_aborted()
1865 // flag while there may still be some work to do. (See the comment at
1866 // the beginning of G1CMTask::do_marking_step() for those conditions -
1867 // one of which is reaching the specified time target.) It is only
1868 // when G1CMTask::do_marking_step() returns without setting the
1869 // has_aborted() flag that the marking step has completed.
1870 do {
1871 double mark_step_duration_ms = G1ConcMarkStepDurationMillis;
1872 _task->do_marking_step(mark_step_duration_ms,
1873 false /* do_termination */,
1874 _is_serial);
1875 } while (_task->has_aborted() && !_cm->has_overflown());
1876 _ref_counter = _ref_counter_limit;
1877 }
1878 }
1879 }
1880 };
1881
1882 // 'Drain' oop closure used by both serial and parallel reference processing.
1883 // Uses the G1CMTask associated with a given worker thread (for serial
1884 // reference processing the G1CMtask for worker 0 is used). Calls the
1885 // do_marking_step routine, with an unbelievably large timeout value,
1886 // to drain the marking data structures of the remaining entries
1887 // added by the 'keep alive' oop closure above.
1888
1889 class G1CMDrainMarkingStackClosure: public VoidClosure {
1890 G1ConcurrentMark* _cm;
1891 G1CMTask* _task;
1892 bool _is_serial;
1893 public:
1894 G1CMDrainMarkingStackClosure(G1ConcurrentMark* cm, G1CMTask* task, bool is_serial) :
1895 _cm(cm), _task(task), _is_serial(is_serial) {
1896 assert(!_is_serial || _task->worker_id() == 0, "only task 0 for serial code");
1897 }
1898
1899 void do_void() {
1900 do {
1901 // We call G1CMTask::do_marking_step() to completely drain the local
1902 // and global marking stacks of entries pushed by the 'keep alive'
1903 // oop closure (an instance of G1CMKeepAliveAndDrainClosure above).
1904 //
1905 // G1CMTask::do_marking_step() is called in a loop, which we'll exit
1906 // if there's nothing more to do (i.e. we've completely drained the
1907 // entries that were pushed as a a result of applying the 'keep alive'
1908 // closure to the entries on the discovered ref lists) or we overflow
1909 // the global marking stack.
1910 //
1911 // Note: G1CMTask::do_marking_step() can set the G1CMTask::has_aborted()
1912 // flag while there may still be some work to do. (See the comment at
1913 // the beginning of G1CMTask::do_marking_step() for those conditions -
1914 // one of which is reaching the specified time target.) It is only
1915 // when G1CMTask::do_marking_step() returns without setting the
1916 // has_aborted() flag that the marking step has completed.
1917
1918 _task->do_marking_step(1000000000.0 /* something very large */,
1919 true /* do_termination */,
1920 _is_serial);
1921 } while (_task->has_aborted() && !_cm->has_overflown());
1922 }
1923 };
1924
1925 // Implementation of AbstractRefProcTaskExecutor for parallel
1926 // reference processing at the end of G1 concurrent marking
1927
1928 class G1CMRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
1929 private:
1930 G1CollectedHeap* _g1h;
1931 G1ConcurrentMark* _cm;
1932 WorkGang* _workers;
1933 uint _active_workers;
1934
1935 public:
1936 G1CMRefProcTaskExecutor(G1CollectedHeap* g1h,
1937 G1ConcurrentMark* cm,
1938 WorkGang* workers,
1939 uint n_workers) :
1940 _g1h(g1h), _cm(cm),
1941 _workers(workers), _active_workers(n_workers) { }
1942
1943 // Executes the given task using concurrent marking worker threads.
1944 virtual void execute(ProcessTask& task);
1945 virtual void execute(EnqueueTask& task);
1946 };
1947
1948 class G1CMRefProcTaskProxy: public AbstractGangTask {
1949 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
1950 ProcessTask& _proc_task;
1951 G1CollectedHeap* _g1h;
1952 G1ConcurrentMark* _cm;
1953
1954 public:
1955 G1CMRefProcTaskProxy(ProcessTask& proc_task,
1956 G1CollectedHeap* g1h,
1957 G1ConcurrentMark* cm) :
1958 AbstractGangTask("Process reference objects in parallel"),
1959 _proc_task(proc_task), _g1h(g1h), _cm(cm) {
1960 ReferenceProcessor* rp = _g1h->ref_processor_cm();
1961 assert(rp->processing_is_mt(), "shouldn't be here otherwise");
1962 }
1963
1964 virtual void work(uint worker_id) {
1965 ResourceMark rm;
1966 HandleMark hm;
1967 G1CMTask* task = _cm->task(worker_id);
1968 G1CMIsAliveClosure g1_is_alive(_g1h);
1969 G1CMKeepAliveAndDrainClosure g1_par_keep_alive(_cm, task, false /* is_serial */);
1970 G1CMDrainMarkingStackClosure g1_par_drain(_cm, task, false /* is_serial */);
1971
1972 _proc_task.work(worker_id, g1_is_alive, g1_par_keep_alive, g1_par_drain);
1973 }
1974 };
1975
1976 void G1CMRefProcTaskExecutor::execute(ProcessTask& proc_task) {
1977 assert(_workers != NULL, "Need parallel worker threads.");
1978 assert(_g1h->ref_processor_cm()->processing_is_mt(), "processing is not MT");
1979
1980 G1CMRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _cm);
1981
1982 // We need to reset the concurrency level before each
1983 // proxy task execution, so that the termination protocol
1984 // and overflow handling in G1CMTask::do_marking_step() knows
1985 // how many workers to wait for.
1986 _cm->set_concurrency(_active_workers);
1987 _workers->run_task(&proc_task_proxy);
1988 }
1989
1990 class G1CMRefEnqueueTaskProxy: public AbstractGangTask {
1991 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
1992 EnqueueTask& _enq_task;
1993
1994 public:
1995 G1CMRefEnqueueTaskProxy(EnqueueTask& enq_task) :
1996 AbstractGangTask("Enqueue reference objects in parallel"),
1997 _enq_task(enq_task) { }
1998
1999 virtual void work(uint worker_id) {
2000 _enq_task.work(worker_id);
2001 }
2002 };
2003
2004 void G1CMRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
2005 assert(_workers != NULL, "Need parallel worker threads.");
2006 assert(_g1h->ref_processor_cm()->processing_is_mt(), "processing is not MT");
2007
2008 G1CMRefEnqueueTaskProxy enq_task_proxy(enq_task);
2009
2010 // Not strictly necessary but...
2011 //
2012 // We need to reset the concurrency level before each
2013 // proxy task execution, so that the termination protocol
2014 // and overflow handling in G1CMTask::do_marking_step() knows
2015 // how many workers to wait for.
2016 _cm->set_concurrency(_active_workers);
2017 _workers->run_task(&enq_task_proxy);
2018 }
2019
2020 void G1ConcurrentMark::weakRefsWorkParallelPart(BoolObjectClosure* is_alive, bool purged_classes) {
2021 G1CollectedHeap::heap()->parallel_cleaning(is_alive, true, true, purged_classes);
2022 }
2023
2024 void G1ConcurrentMark::weakRefsWork(bool clear_all_soft_refs) {
2025 if (has_overflown()) {
2026 // Skip processing the discovered references if we have
2027 // overflown the global marking stack. Reference objects
2028 // only get discovered once so it is OK to not
2029 // de-populate the discovered reference lists. We could have,
2030 // but the only benefit would be that, when marking restarts,
2031 // less reference objects are discovered.
2032 return;
2033 }
2034
2035 ResourceMark rm;
2036 HandleMark hm;
2037
2038 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2039
2040 // Is alive closure.
2041 G1CMIsAliveClosure g1_is_alive(g1h);
2042
2043 // Inner scope to exclude the cleaning of the string and symbol
2044 // tables from the displayed time.
2045 {
2046 GCTraceTime(Debug, gc) trace("Reference Processing", g1h->gc_timer_cm());
2047
2048 ReferenceProcessor* rp = g1h->ref_processor_cm();
2049
2050 // See the comment in G1CollectedHeap::ref_processing_init()
2051 // about how reference processing currently works in G1.
2052
2053 // Set the soft reference policy
2054 rp->setup_policy(clear_all_soft_refs);
2055 assert(_markStack.isEmpty(), "mark stack should be empty");
2056
2057 // Instances of the 'Keep Alive' and 'Complete GC' closures used
2058 // in serial reference processing. Note these closures are also
2059 // used for serially processing (by the the current thread) the
2060 // JNI references during parallel reference processing.
2061 //
2062 // These closures do not need to synchronize with the worker
2063 // threads involved in parallel reference processing as these
2064 // instances are executed serially by the current thread (e.g.
2065 // reference processing is not multi-threaded and is thus
2066 // performed by the current thread instead of a gang worker).
2067 //
2068 // The gang tasks involved in parallel reference processing create
2069 // their own instances of these closures, which do their own
2070 // synchronization among themselves.
2071 G1CMKeepAliveAndDrainClosure g1_keep_alive(this, task(0), true /* is_serial */);
2072 G1CMDrainMarkingStackClosure g1_drain_mark_stack(this, task(0), true /* is_serial */);
2073
2074 // We need at least one active thread. If reference processing
2075 // is not multi-threaded we use the current (VMThread) thread,
2076 // otherwise we use the work gang from the G1CollectedHeap and
2077 // we utilize all the worker threads we can.
2078 bool processing_is_mt = rp->processing_is_mt();
2079 uint active_workers = (processing_is_mt ? g1h->workers()->active_workers() : 1U);
2080 active_workers = MAX2(MIN2(active_workers, _max_worker_id), 1U);
2081
2082 // Parallel processing task executor.
2083 G1CMRefProcTaskExecutor par_task_executor(g1h, this,
2084 g1h->workers(), active_workers);
2085 AbstractRefProcTaskExecutor* executor = (processing_is_mt ? &par_task_executor : NULL);
2086
2087 // Set the concurrency level. The phase was already set prior to
2088 // executing the remark task.
2089 set_concurrency(active_workers);
2090
2091 // Set the degree of MT processing here. If the discovery was done MT,
2092 // the number of threads involved during discovery could differ from
2093 // the number of active workers. This is OK as long as the discovered
2094 // Reference lists are balanced (see balance_all_queues() and balance_queues()).
2095 rp->set_active_mt_degree(active_workers);
2096
2097 // Process the weak references.
2098 const ReferenceProcessorStats& stats =
2099 rp->process_discovered_references(&g1_is_alive,
2100 &g1_keep_alive,
2101 &g1_drain_mark_stack,
2102 executor,
2103 g1h->gc_timer_cm());
2104 g1h->gc_tracer_cm()->report_gc_reference_stats(stats);
2105
2106 // The do_oop work routines of the keep_alive and drain_marking_stack
2107 // oop closures will set the has_overflown flag if we overflow the
2108 // global marking stack.
2109
2110 assert(_markStack.overflow() || _markStack.isEmpty(),
2111 "mark stack should be empty (unless it overflowed)");
2112
2113 if (_markStack.overflow()) {
2114 // This should have been done already when we tried to push an
2115 // entry on to the global mark stack. But let's do it again.
2116 set_has_overflown();
2117 }
2118
2119 assert(rp->num_q() == active_workers, "why not");
2120
2121 rp->enqueue_discovered_references(executor);
2122
2123 rp->verify_no_references_recorded();
2124 assert(!rp->discovery_enabled(), "Post condition");
2125 }
2126
2127 if (has_overflown()) {
2128 // We can not trust g1_is_alive if the marking stack overflowed
2129 return;
2130 }
2131
2132 assert(_markStack.isEmpty(), "Marking should have completed");
2133
2134 // Unload Klasses, String, Symbols, Code Cache, etc.
2135 {
2136 GCTraceTime(Debug, gc) trace("Unloading", g1h->gc_timer_cm());
2137
2138 if (ClassUnloadingWithConcurrentMark) {
2139 bool purged_classes;
2140
2141 {
2142 GCTraceTime(Trace, gc) trace("System Dictionary Unloading", g1h->gc_timer_cm());
2143 purged_classes = SystemDictionary::do_unloading(&g1_is_alive, false /* Defer klass cleaning */);
2144 }
2145
2146 {
2147 GCTraceTime(Trace, gc) trace("Parallel Unloading", g1h->gc_timer_cm());
2148 weakRefsWorkParallelPart(&g1_is_alive, purged_classes);
2149 }
2150 }
2151
2152 if (G1StringDedup::is_enabled()) {
2153 GCTraceTime(Trace, gc) trace("String Deduplication Unlink", g1h->gc_timer_cm());
2154 G1StringDedup::unlink(&g1_is_alive);
2155 }
2156 }
2157 }
2158
2159 void G1ConcurrentMark::swapMarkBitMaps() {
2160 G1CMBitMapRO* temp = _prevMarkBitMap;
2161 _prevMarkBitMap = (G1CMBitMapRO*)_nextMarkBitMap;
2162 _nextMarkBitMap = (G1CMBitMap*) temp;
2163 }
2164
2165 // Closure for marking entries in SATB buffers.
2166 class G1CMSATBBufferClosure : public SATBBufferClosure {
2167 private:
2168 G1CMTask* _task;
2169 G1CollectedHeap* _g1h;
2170
2171 // This is very similar to G1CMTask::deal_with_reference, but with
2172 // more relaxed requirements for the argument, so this must be more
2173 // circumspect about treating the argument as an object.
2174 void do_entry(void* entry) const {
2175 _task->increment_refs_reached();
2176 HeapRegion* hr = _g1h->heap_region_containing(entry);
2177 if (entry < hr->next_top_at_mark_start()) {
2178 // Until we get here, we don't know whether entry refers to a valid
2179 // object; it could instead have been a stale reference.
2180 oop obj = static_cast<oop>(entry);
2181 assert(obj->is_oop(true /* ignore mark word */),
2182 "Invalid oop in SATB buffer: " PTR_FORMAT, p2i(obj));
2183 _task->make_reference_grey(obj, hr);
2184 }
2185 }
2186
2187 public:
2188 G1CMSATBBufferClosure(G1CMTask* task, G1CollectedHeap* g1h)
2189 : _task(task), _g1h(g1h) { }
2190
2191 virtual void do_buffer(void** buffer, size_t size) {
2192 for (size_t i = 0; i < size; ++i) {
2193 do_entry(buffer[i]);
2194 }
2195 }
2196 };
2197
2198 class G1RemarkThreadsClosure : public ThreadClosure {
2199 G1CMSATBBufferClosure _cm_satb_cl;
2200 G1CMOopClosure _cm_cl;
2201 MarkingCodeBlobClosure _code_cl;
2202 int _thread_parity;
2203
2204 public:
2205 G1RemarkThreadsClosure(G1CollectedHeap* g1h, G1CMTask* task) :
2206 _cm_satb_cl(task, g1h),
2207 _cm_cl(g1h, g1h->concurrent_mark(), task),
2208 _code_cl(&_cm_cl, !CodeBlobToOopClosure::FixRelocations),
2209 _thread_parity(Threads::thread_claim_parity()) {}
2210
2211 void do_thread(Thread* thread) {
2212 if (thread->is_Java_thread()) {
2213 if (thread->claim_oops_do(true, _thread_parity)) {
2214 JavaThread* jt = (JavaThread*)thread;
2215
2216 // In theory it should not be neccessary to explicitly walk the nmethods to find roots for concurrent marking
2217 // however the liveness of oops reachable from nmethods have very complex lifecycles:
2218 // * Alive if on the stack of an executing method
2219 // * Weakly reachable otherwise
2220 // Some objects reachable from nmethods, such as the class loader (or klass_holder) of the receiver should be
2221 // live by the SATB invariant but other oops recorded in nmethods may behave differently.
2222 jt->nmethods_do(&_code_cl);
2223
2224 jt->satb_mark_queue().apply_closure_and_empty(&_cm_satb_cl);
2225 }
2226 } else if (thread->is_VM_thread()) {
2227 if (thread->claim_oops_do(true, _thread_parity)) {
2228 JavaThread::satb_mark_queue_set().shared_satb_queue()->apply_closure_and_empty(&_cm_satb_cl);
2229 }
2230 }
2231 }
2232 };
2233
2234 class G1CMRemarkTask: public AbstractGangTask {
2235 private:
2236 G1ConcurrentMark* _cm;
2237 public:
2238 void work(uint worker_id) {
2239 // Since all available tasks are actually started, we should
2240 // only proceed if we're supposed to be active.
2241 if (worker_id < _cm->active_tasks()) {
2242 G1CMTask* task = _cm->task(worker_id);
2243 task->record_start_time();
2244 {
2245 ResourceMark rm;
2246 HandleMark hm;
2247
2248 G1RemarkThreadsClosure threads_f(G1CollectedHeap::heap(), task);
2249 Threads::threads_do(&threads_f);
2250 }
2251
2252 do {
2253 task->do_marking_step(1000000000.0 /* something very large */,
2254 true /* do_termination */,
2255 false /* is_serial */);
2256 } while (task->has_aborted() && !_cm->has_overflown());
2257 // If we overflow, then we do not want to restart. We instead
2258 // want to abort remark and do concurrent marking again.
2259 task->record_end_time();
2260 }
2261 }
2262
2263 G1CMRemarkTask(G1ConcurrentMark* cm, uint active_workers) :
2264 AbstractGangTask("Par Remark"), _cm(cm) {
2265 _cm->terminator()->reset_for_reuse(active_workers);
2266 }
2267 };
2268
2269 void G1ConcurrentMark::checkpointRootsFinalWork() {
2270 ResourceMark rm;
2271 HandleMark hm;
2272 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2273
2274 GCTraceTime(Debug, gc) trace("Finalize Marking", g1h->gc_timer_cm());
2275
2276 g1h->ensure_parsability(false);
2277
2278 // this is remark, so we'll use up all active threads
2279 uint active_workers = g1h->workers()->active_workers();
2280 set_concurrency_and_phase(active_workers, false /* concurrent */);
2281 // Leave _parallel_marking_threads at it's
2282 // value originally calculated in the G1ConcurrentMark
2283 // constructor and pass values of the active workers
2284 // through the gang in the task.
2285
2286 {
2287 StrongRootsScope srs(active_workers);
2288
2289 G1CMRemarkTask remarkTask(this, active_workers);
2290 // We will start all available threads, even if we decide that the
2291 // active_workers will be fewer. The extra ones will just bail out
2292 // immediately.
2293 g1h->workers()->run_task(&remarkTask);
2294 }
2295
2296 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
2297 guarantee(has_overflown() ||
2298 satb_mq_set.completed_buffers_num() == 0,
2299 "Invariant: has_overflown = %s, num buffers = " SIZE_FORMAT,
2300 BOOL_TO_STR(has_overflown()),
2301 satb_mq_set.completed_buffers_num());
2302
2303 print_stats();
2304 }
2305
2306 void G1ConcurrentMark::clearRangePrevBitmap(MemRegion mr) {
2307 // Note we are overriding the read-only view of the prev map here, via
2308 // the cast.
2309 ((G1CMBitMap*)_prevMarkBitMap)->clearRange(mr);
2310 }
2311
2312 HeapRegion*
2313 G1ConcurrentMark::claim_region(uint worker_id) {
2314 // "checkpoint" the finger
2315 HeapWord* finger = _finger;
2316
2317 // _heap_end will not change underneath our feet; it only changes at
2318 // yield points.
2319 while (finger < _heap_end) {
2320 assert(_g1h->is_in_g1_reserved(finger), "invariant");
2321
2322 HeapRegion* curr_region = _g1h->heap_region_containing(finger);
2323
2324 // Above heap_region_containing may return NULL as we always scan claim
2325 // until the end of the heap. In this case, just jump to the next region.
2326 HeapWord* end = curr_region != NULL ? curr_region->end() : finger + HeapRegion::GrainWords;
2327
2328 // Is the gap between reading the finger and doing the CAS too long?
2329 HeapWord* res = (HeapWord*) Atomic::cmpxchg_ptr(end, &_finger, finger);
2330 if (res == finger && curr_region != NULL) {
2331 // we succeeded
2332 HeapWord* bottom = curr_region->bottom();
2333 HeapWord* limit = curr_region->next_top_at_mark_start();
2334
2335 // notice that _finger == end cannot be guaranteed here since,
2336 // someone else might have moved the finger even further
2337 assert(_finger >= end, "the finger should have moved forward");
2338
2339 if (limit > bottom) {
2340 return curr_region;
2341 } else {
2342 assert(limit == bottom,
2343 "the region limit should be at bottom");
2344 // we return NULL and the caller should try calling
2345 // claim_region() again.
2346 return NULL;
2347 }
2348 } else {
2349 assert(_finger > finger, "the finger should have moved forward");
2350 // read it again
2351 finger = _finger;
2352 }
2353 }
2354
2355 return NULL;
2356 }
2357
2358 #ifndef PRODUCT
2359 class VerifyNoCSetOops VALUE_OBJ_CLASS_SPEC {
2360 private:
2361 G1CollectedHeap* _g1h;
2362 const char* _phase;
2363 int _info;
2364
2365 public:
2366 VerifyNoCSetOops(const char* phase, int info = -1) :
2367 _g1h(G1CollectedHeap::heap()),
2368 _phase(phase),
2369 _info(info)
2370 { }
2371
2372 void operator()(oop obj) const {
2373 guarantee(obj->is_oop(),
2374 "Non-oop " PTR_FORMAT ", phase: %s, info: %d",
2375 p2i(obj), _phase, _info);
2376 guarantee(!_g1h->obj_in_cs(obj),
2377 "obj: " PTR_FORMAT " in CSet, phase: %s, info: %d",
2378 p2i(obj), _phase, _info);
2379 }
2380 };
2381
2382 void G1ConcurrentMark::verify_no_cset_oops() {
2383 assert(SafepointSynchronize::is_at_safepoint(), "should be at a safepoint");
2384 if (!G1CollectedHeap::heap()->collector_state()->mark_in_progress()) {
2385 return;
2386 }
2387
2388 // Verify entries on the global mark stack
2389 _markStack.iterate(VerifyNoCSetOops("Stack"));
2390
2391 // Verify entries on the task queues
2392 for (uint i = 0; i < _max_worker_id; ++i) {
2393 G1CMTaskQueue* queue = _task_queues->queue(i);
2394 queue->iterate(VerifyNoCSetOops("Queue", i));
2395 }
2396
2397 // Verify the global finger
2398 HeapWord* global_finger = finger();
2399 if (global_finger != NULL && global_finger < _heap_end) {
2400 // Since we always iterate over all regions, we might get a NULL HeapRegion
2401 // here.
2402 HeapRegion* global_hr = _g1h->heap_region_containing(global_finger);
2403 guarantee(global_hr == NULL || global_finger == global_hr->bottom(),
2404 "global finger: " PTR_FORMAT " region: " HR_FORMAT,
2405 p2i(global_finger), HR_FORMAT_PARAMS(global_hr));
2406 }
2407
2408 // Verify the task fingers
2409 assert(parallel_marking_threads() <= _max_worker_id, "sanity");
2410 for (uint i = 0; i < parallel_marking_threads(); ++i) {
2411 G1CMTask* task = _tasks[i];
2412 HeapWord* task_finger = task->finger();
2413 if (task_finger != NULL && task_finger < _heap_end) {
2414 // See above note on the global finger verification.
2415 HeapRegion* task_hr = _g1h->heap_region_containing(task_finger);
2416 guarantee(task_hr == NULL || task_finger == task_hr->bottom() ||
2417 !task_hr->in_collection_set(),
2418 "task finger: " PTR_FORMAT " region: " HR_FORMAT,
2419 p2i(task_finger), HR_FORMAT_PARAMS(task_hr));
2420 }
2421 }
2422 }
2423 #endif // PRODUCT
2424
2425 // Aggregate the counting data that was constructed concurrently
2426 // with marking.
2427 class AggregateCountDataHRClosure: public HeapRegionClosure {
2428 G1CollectedHeap* _g1h;
2429 G1ConcurrentMark* _cm;
2430 CardTableModRefBS* _ct_bs;
2431 BitMap* _cm_card_bm;
2432 uint _max_worker_id;
2433
2434 public:
2435 AggregateCountDataHRClosure(G1CollectedHeap* g1h,
2436 BitMap* cm_card_bm,
2437 uint max_worker_id) :
2438 _g1h(g1h), _cm(g1h->concurrent_mark()),
2439 _ct_bs(barrier_set_cast<CardTableModRefBS>(g1h->barrier_set())),
2440 _cm_card_bm(cm_card_bm), _max_worker_id(max_worker_id) { }
2441
2442 bool doHeapRegion(HeapRegion* hr) {
2443 HeapWord* start = hr->bottom();
2444 HeapWord* limit = hr->next_top_at_mark_start();
2445 HeapWord* end = hr->end();
2446
2447 assert(start <= limit && limit <= hr->top() && hr->top() <= hr->end(),
2448 "Preconditions not met - "
2449 "start: " PTR_FORMAT ", limit: " PTR_FORMAT ", "
2450 "top: " PTR_FORMAT ", end: " PTR_FORMAT,
2451 p2i(start), p2i(limit), p2i(hr->top()), p2i(hr->end()));
2452
2453 assert(hr->next_marked_bytes() == 0, "Precondition");
2454
2455 if (start == limit) {
2456 // NTAMS of this region has not been set so nothing to do.
2457 return false;
2458 }
2459
2460 // 'start' should be in the heap.
2461 assert(_g1h->is_in_g1_reserved(start) && _ct_bs->is_card_aligned(start), "sanity");
2462 // 'end' *may* be just beyond the end of the heap (if hr is the last region)
2463 assert(!_g1h->is_in_g1_reserved(end) || _ct_bs->is_card_aligned(end), "sanity");
2464
2465 BitMap::idx_t start_idx = _cm->card_bitmap_index_for(start);
2466 BitMap::idx_t limit_idx = _cm->card_bitmap_index_for(limit);
2467 BitMap::idx_t end_idx = _cm->card_bitmap_index_for(end);
2468
2469 // If ntams is not card aligned then we bump card bitmap index
2470 // for limit so that we get the all the cards spanned by
2471 // the object ending at ntams.
2472 // Note: if this is the last region in the heap then ntams
2473 // could be actually just beyond the end of the the heap;
2474 // limit_idx will then correspond to a (non-existent) card
2475 // that is also outside the heap.
2476 if (_g1h->is_in_g1_reserved(limit) && !_ct_bs->is_card_aligned(limit)) {
2477 limit_idx += 1;
2478 }
2479
2480 assert(limit_idx <= end_idx, "or else use atomics");
2481
2482 // Aggregate the "stripe" in the count data associated with hr.
2483 uint hrm_index = hr->hrm_index();
2484 size_t marked_bytes = 0;
2485
2486 for (uint i = 0; i < _max_worker_id; i += 1) {
2487 size_t* marked_bytes_array = _cm->count_marked_bytes_array_for(i);
2488 BitMap* task_card_bm = _cm->count_card_bitmap_for(i);
2489
2490 // Fetch the marked_bytes in this region for task i and
2491 // add it to the running total for this region.
2492 marked_bytes += marked_bytes_array[hrm_index];
2493
2494 // Now union the bitmaps[0,max_worker_id)[start_idx..limit_idx)
2495 // into the global card bitmap.
2496 BitMap::idx_t scan_idx = task_card_bm->get_next_one_offset(start_idx, limit_idx);
2497
2498 while (scan_idx < limit_idx) {
2499 assert(task_card_bm->at(scan_idx) == true, "should be");
2500 _cm_card_bm->set_bit(scan_idx);
2501 assert(_cm_card_bm->at(scan_idx) == true, "should be");
2502
2503 // BitMap::get_next_one_offset() can handle the case when
2504 // its left_offset parameter is greater than its right_offset
2505 // parameter. It does, however, have an early exit if
2506 // left_offset == right_offset. So let's limit the value
2507 // passed in for left offset here.
2508 BitMap::idx_t next_idx = MIN2(scan_idx + 1, limit_idx);
2509 scan_idx = task_card_bm->get_next_one_offset(next_idx, limit_idx);
2510 }
2511 }
2512
2513 // Update the marked bytes for this region.
2514 hr->add_to_marked_bytes(marked_bytes);
2515
2516 // Next heap region
2517 return false;
2518 }
2519 };
2520
2521 class G1AggregateCountDataTask: public AbstractGangTask {
2522 protected:
2523 G1CollectedHeap* _g1h;
2524 G1ConcurrentMark* _cm;
2525 BitMap* _cm_card_bm;
2526 uint _max_worker_id;
2527 uint _active_workers;
2528 HeapRegionClaimer _hrclaimer;
2529
2530 public:
2531 G1AggregateCountDataTask(G1CollectedHeap* g1h,
2532 G1ConcurrentMark* cm,
2533 BitMap* cm_card_bm,
2534 uint max_worker_id,
2535 uint n_workers) :
2536 AbstractGangTask("Count Aggregation"),
2537 _g1h(g1h), _cm(cm), _cm_card_bm(cm_card_bm),
2538 _max_worker_id(max_worker_id),
2539 _active_workers(n_workers),
2540 _hrclaimer(_active_workers) {
2541 }
2542
2543 void work(uint worker_id) {
2544 AggregateCountDataHRClosure cl(_g1h, _cm_card_bm, _max_worker_id);
2545
2546 _g1h->heap_region_par_iterate(&cl, worker_id, &_hrclaimer);
2547 }
2548 };
2549
2550
2551 void G1ConcurrentMark::aggregate_count_data() {
2552 uint n_workers = _g1h->workers()->active_workers();
2553
2554 G1AggregateCountDataTask g1_par_agg_task(_g1h, this, &_card_bm,
2555 _max_worker_id, n_workers);
2556
2557 _g1h->workers()->run_task(&g1_par_agg_task);
2558 }
2559
2560 // Clear the per-worker arrays used to store the per-region counting data
2561 void G1ConcurrentMark::clear_all_count_data() {
2562 // Clear the global card bitmap - it will be filled during
2563 // liveness count aggregation (during remark) and the
2564 // final counting task.
2565 _card_bm.clear();
2566
2567 // Clear the global region bitmap - it will be filled as part
2568 // of the final counting task.
2569 _region_bm.clear();
2570
2571 uint max_regions = _g1h->max_regions();
2572 assert(_max_worker_id > 0, "uninitialized");
2573
2574 for (uint i = 0; i < _max_worker_id; i += 1) {
2575 BitMap* task_card_bm = count_card_bitmap_for(i);
2576 size_t* marked_bytes_array = count_marked_bytes_array_for(i);
2577
2578 assert(task_card_bm->size() == _card_bm.size(), "size mismatch");
2579 assert(marked_bytes_array != NULL, "uninitialized");
2580
2581 memset(marked_bytes_array, 0, (size_t) max_regions * sizeof(size_t));
2582 task_card_bm->clear();
2583 }
2584 }
2585
2586 void G1ConcurrentMark::print_stats() {
2587 if (!log_is_enabled(Debug, gc, stats)) {
2588 return;
2589 }
2590 log_debug(gc, stats)("---------------------------------------------------------------------");
2591 for (size_t i = 0; i < _active_tasks; ++i) {
2592 _tasks[i]->print_stats();
2593 log_debug(gc, stats)("---------------------------------------------------------------------");
2594 }
2595 }
2596
2597 // abandon current marking iteration due to a Full GC
2598 void G1ConcurrentMark::abort() {
2599 if (!cmThread()->during_cycle() || _has_aborted) {
2600 // We haven't started a concurrent cycle or we have already aborted it. No need to do anything.
2601 return;
2602 }
2603
2604 // Clear all marks in the next bitmap for the next marking cycle. This will allow us to skip the next
2605 // concurrent bitmap clearing.
2606 _nextMarkBitMap->clearAll();
2607
2608 // Note we cannot clear the previous marking bitmap here
2609 // since VerifyDuringGC verifies the objects marked during
2610 // a full GC against the previous bitmap.
2611
2612 // Clear the liveness counting data
2613 clear_all_count_data();
2614 // Empty mark stack
2615 reset_marking_state();
2616 for (uint i = 0; i < _max_worker_id; ++i) {
2617 _tasks[i]->clear_region_fields();
2618 }
2619 _first_overflow_barrier_sync.abort();
2620 _second_overflow_barrier_sync.abort();
2621 _has_aborted = true;
2622
2623 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
2624 satb_mq_set.abandon_partial_marking();
2625 // This can be called either during or outside marking, we'll read
2626 // the expected_active value from the SATB queue set.
2627 satb_mq_set.set_active_all_threads(
2628 false, /* new active value */
2629 satb_mq_set.is_active() /* expected_active */);
2630
2631 _g1h->trace_heap_after_concurrent_cycle();
2632
2633 _g1h->register_concurrent_cycle_end();
2634 }
2635
2636 static void print_ms_time_info(const char* prefix, const char* name,
2637 NumberSeq& ns) {
2638 log_trace(gc, marking)("%s%5d %12s: total time = %8.2f s (avg = %8.2f ms).",
2639 prefix, ns.num(), name, ns.sum()/1000.0, ns.avg());
2640 if (ns.num() > 0) {
2641 log_trace(gc, marking)("%s [std. dev = %8.2f ms, max = %8.2f ms]",
2642 prefix, ns.sd(), ns.maximum());
2643 }
2644 }
2645
2646 void G1ConcurrentMark::print_summary_info() {
2647 LogHandle(gc, marking) log;
2648 if (!log.is_trace()) {
2649 return;
2650 }
2651
2652 log.trace(" Concurrent marking:");
2653 print_ms_time_info(" ", "init marks", _init_times);
2654 print_ms_time_info(" ", "remarks", _remark_times);
2655 {
2656 print_ms_time_info(" ", "final marks", _remark_mark_times);
2657 print_ms_time_info(" ", "weak refs", _remark_weak_ref_times);
2658
2659 }
2660 print_ms_time_info(" ", "cleanups", _cleanup_times);
2661 log.trace(" Final counting total time = %8.2f s (avg = %8.2f ms).",
2662 _total_counting_time, (_cleanup_times.num() > 0 ? _total_counting_time * 1000.0 / (double)_cleanup_times.num() : 0.0));
2663 if (G1ScrubRemSets) {
2664 log.trace(" RS scrub total time = %8.2f s (avg = %8.2f ms).",
2665 _total_rs_scrub_time, (_cleanup_times.num() > 0 ? _total_rs_scrub_time * 1000.0 / (double)_cleanup_times.num() : 0.0));
2666 }
2667 log.trace(" Total stop_world time = %8.2f s.",
2668 (_init_times.sum() + _remark_times.sum() + _cleanup_times.sum())/1000.0);
2669 log.trace(" Total concurrent time = %8.2f s (%8.2f s marking).",
2670 cmThread()->vtime_accum(), cmThread()->vtime_mark_accum());
2671 }
2672
2673 void G1ConcurrentMark::print_worker_threads_on(outputStream* st) const {
2674 _parallel_workers->print_worker_threads_on(st);
2675 }
2676
2677 void G1ConcurrentMark::print_on_error(outputStream* st) const {
2678 st->print_cr("Marking Bits (Prev, Next): (CMBitMap*) " PTR_FORMAT ", (CMBitMap*) " PTR_FORMAT,
2679 p2i(_prevMarkBitMap), p2i(_nextMarkBitMap));
2680 _prevMarkBitMap->print_on_error(st, " Prev Bits: ");
2681 _nextMarkBitMap->print_on_error(st, " Next Bits: ");
2682 }
2683
2684 // We take a break if someone is trying to stop the world.
2685 bool G1ConcurrentMark::do_yield_check(uint worker_id) {
2686 if (SuspendibleThreadSet::should_yield()) {
2687 SuspendibleThreadSet::yield();
2688 return true;
2689 } else {
2690 return false;
2691 }
2692 }
2693
2694 // Closure for iteration over bitmaps
2695 class G1CMBitMapClosure : public BitMapClosure {
2696 private:
2697 // the bitmap that is being iterated over
2698 G1CMBitMap* _nextMarkBitMap;
2699 G1ConcurrentMark* _cm;
2700 G1CMTask* _task;
2701
2702 public:
2703 G1CMBitMapClosure(G1CMTask *task, G1ConcurrentMark* cm, G1CMBitMap* nextMarkBitMap) :
2704 _task(task), _cm(cm), _nextMarkBitMap(nextMarkBitMap) { }
2705
2706 bool do_bit(size_t offset) {
2707 HeapWord* addr = _nextMarkBitMap->offsetToHeapWord(offset);
2708 assert(_nextMarkBitMap->isMarked(addr), "invariant");
2709 assert( addr < _cm->finger(), "invariant");
2710 assert(addr >= _task->finger(), "invariant");
2711
2712 // We move that task's local finger along.
2713 _task->move_finger_to(addr);
2714
2715 _task->scan_object(oop(addr));
2716 // we only partially drain the local queue and global stack
2717 _task->drain_local_queue(true);
2718 _task->drain_global_stack(true);
2719
2720 // if the has_aborted flag has been raised, we need to bail out of
2721 // the iteration
2722 return !_task->has_aborted();
2723 }
2724 };
2725
2726 static ReferenceProcessor* get_cm_oop_closure_ref_processor(G1CollectedHeap* g1h) {
2727 ReferenceProcessor* result = g1h->ref_processor_cm();
2728 assert(result != NULL, "CM reference processor should not be NULL");
2729 return result;
2730 }
2731
2732 G1CMOopClosure::G1CMOopClosure(G1CollectedHeap* g1h,
2733 G1ConcurrentMark* cm,
2734 G1CMTask* task)
2735 : MetadataAwareOopClosure(get_cm_oop_closure_ref_processor(g1h)),
2736 _g1h(g1h), _cm(cm), _task(task)
2737 { }
2738
2739 void G1CMTask::setup_for_region(HeapRegion* hr) {
2740 assert(hr != NULL,
2741 "claim_region() should have filtered out NULL regions");
2742 _curr_region = hr;
2743 _finger = hr->bottom();
2744 update_region_limit();
2745 }
2746
2747 void G1CMTask::update_region_limit() {
2748 HeapRegion* hr = _curr_region;
2749 HeapWord* bottom = hr->bottom();
2750 HeapWord* limit = hr->next_top_at_mark_start();
2751
2752 if (limit == bottom) {
2753 // The region was collected underneath our feet.
2754 // We set the finger to bottom to ensure that the bitmap
2755 // iteration that will follow this will not do anything.
2756 // (this is not a condition that holds when we set the region up,
2757 // as the region is not supposed to be empty in the first place)
2758 _finger = bottom;
2759 } else if (limit >= _region_limit) {
2760 assert(limit >= _finger, "peace of mind");
2761 } else {
2762 assert(limit < _region_limit, "only way to get here");
2763 // This can happen under some pretty unusual circumstances. An
2764 // evacuation pause empties the region underneath our feet (NTAMS
2765 // at bottom). We then do some allocation in the region (NTAMS
2766 // stays at bottom), followed by the region being used as a GC
2767 // alloc region (NTAMS will move to top() and the objects
2768 // originally below it will be grayed). All objects now marked in
2769 // the region are explicitly grayed, if below the global finger,
2770 // and we do not need in fact to scan anything else. So, we simply
2771 // set _finger to be limit to ensure that the bitmap iteration
2772 // doesn't do anything.
2773 _finger = limit;
2774 }
2775
2776 _region_limit = limit;
2777 }
2778
2779 void G1CMTask::giveup_current_region() {
2780 assert(_curr_region != NULL, "invariant");
2781 clear_region_fields();
2782 }
2783
2784 void G1CMTask::clear_region_fields() {
2785 // Values for these three fields that indicate that we're not
2786 // holding on to a region.
2787 _curr_region = NULL;
2788 _finger = NULL;
2789 _region_limit = NULL;
2790 }
2791
2792 void G1CMTask::set_cm_oop_closure(G1CMOopClosure* cm_oop_closure) {
2793 if (cm_oop_closure == NULL) {
2794 assert(_cm_oop_closure != NULL, "invariant");
2795 } else {
2796 assert(_cm_oop_closure == NULL, "invariant");
2797 }
2798 _cm_oop_closure = cm_oop_closure;
2799 }
2800
2801 void G1CMTask::reset(G1CMBitMap* nextMarkBitMap) {
2802 guarantee(nextMarkBitMap != NULL, "invariant");
2803 _nextMarkBitMap = nextMarkBitMap;
2804 clear_region_fields();
2805
2806 _calls = 0;
2807 _elapsed_time_ms = 0.0;
2808 _termination_time_ms = 0.0;
2809 _termination_start_time_ms = 0.0;
2810 }
2811
2812 bool G1CMTask::should_exit_termination() {
2813 regular_clock_call();
2814 // This is called when we are in the termination protocol. We should
2815 // quit if, for some reason, this task wants to abort or the global
2816 // stack is not empty (this means that we can get work from it).
2817 return !_cm->mark_stack_empty() || has_aborted();
2818 }
2819
2820 void G1CMTask::reached_limit() {
2821 assert(_words_scanned >= _words_scanned_limit ||
2822 _refs_reached >= _refs_reached_limit ,
2823 "shouldn't have been called otherwise");
2824 regular_clock_call();
2825 }
2826
2827 void G1CMTask::regular_clock_call() {
2828 if (has_aborted()) return;
2829
2830 // First, we need to recalculate the words scanned and refs reached
2831 // limits for the next clock call.
2832 recalculate_limits();
2833
2834 // During the regular clock call we do the following
2835
2836 // (1) If an overflow has been flagged, then we abort.
2837 if (_cm->has_overflown()) {
2838 set_has_aborted();
2839 return;
2840 }
2841
2842 // If we are not concurrent (i.e. we're doing remark) we don't need
2843 // to check anything else. The other steps are only needed during
2844 // the concurrent marking phase.
2845 if (!concurrent()) return;
2846
2847 // (2) If marking has been aborted for Full GC, then we also abort.
2848 if (_cm->has_aborted()) {
2849 set_has_aborted();
2850 return;
2851 }
2852
2853 double curr_time_ms = os::elapsedVTime() * 1000.0;
2854
2855 // (4) We check whether we should yield. If we have to, then we abort.
2856 if (SuspendibleThreadSet::should_yield()) {
2857 // We should yield. To do this we abort the task. The caller is
2858 // responsible for yielding.
2859 set_has_aborted();
2860 return;
2861 }
2862
2863 // (5) We check whether we've reached our time quota. If we have,
2864 // then we abort.
2865 double elapsed_time_ms = curr_time_ms - _start_time_ms;
2866 if (elapsed_time_ms > _time_target_ms) {
2867 set_has_aborted();
2868 _has_timed_out = true;
2869 return;
2870 }
2871
2872 // (6) Finally, we check whether there are enough completed STAB
2873 // buffers available for processing. If there are, we abort.
2874 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
2875 if (!_draining_satb_buffers && satb_mq_set.process_completed_buffers()) {
2876 // we do need to process SATB buffers, we'll abort and restart
2877 // the marking task to do so
2878 set_has_aborted();
2879 return;
2880 }
2881 }
2882
2883 void G1CMTask::recalculate_limits() {
2884 _real_words_scanned_limit = _words_scanned + words_scanned_period;
2885 _words_scanned_limit = _real_words_scanned_limit;
2886
2887 _real_refs_reached_limit = _refs_reached + refs_reached_period;
2888 _refs_reached_limit = _real_refs_reached_limit;
2889 }
2890
2891 void G1CMTask::decrease_limits() {
2892 // This is called when we believe that we're going to do an infrequent
2893 // operation which will increase the per byte scanned cost (i.e. move
2894 // entries to/from the global stack). It basically tries to decrease the
2895 // scanning limit so that the clock is called earlier.
2896
2897 _words_scanned_limit = _real_words_scanned_limit -
2898 3 * words_scanned_period / 4;
2899 _refs_reached_limit = _real_refs_reached_limit -
2900 3 * refs_reached_period / 4;
2901 }
2902
2903 void G1CMTask::move_entries_to_global_stack() {
2904 // local array where we'll store the entries that will be popped
2905 // from the local queue
2906 oop buffer[global_stack_transfer_size];
2907
2908 int n = 0;
2909 oop obj;
2910 while (n < global_stack_transfer_size && _task_queue->pop_local(obj)) {
2911 buffer[n] = obj;
2912 ++n;
2913 }
2914
2915 if (n > 0) {
2916 // we popped at least one entry from the local queue
2917
2918 if (!_cm->mark_stack_push(buffer, n)) {
2919 set_has_aborted();
2920 }
2921 }
2922
2923 // this operation was quite expensive, so decrease the limits
2924 decrease_limits();
2925 }
2926
2927 void G1CMTask::get_entries_from_global_stack() {
2928 // local array where we'll store the entries that will be popped
2929 // from the global stack.
2930 oop buffer[global_stack_transfer_size];
2931 int n;
2932 _cm->mark_stack_pop(buffer, global_stack_transfer_size, &n);
2933 assert(n <= global_stack_transfer_size,
2934 "we should not pop more than the given limit");
2935 if (n > 0) {
2936 // yes, we did actually pop at least one entry
2937 for (int i = 0; i < n; ++i) {
2938 bool success = _task_queue->push(buffer[i]);
2939 // We only call this when the local queue is empty or under a
2940 // given target limit. So, we do not expect this push to fail.
2941 assert(success, "invariant");
2942 }
2943 }
2944
2945 // this operation was quite expensive, so decrease the limits
2946 decrease_limits();
2947 }
2948
2949 void G1CMTask::drain_local_queue(bool partially) {
2950 if (has_aborted()) return;
2951
2952 // Decide what the target size is, depending whether we're going to
2953 // drain it partially (so that other tasks can steal if they run out
2954 // of things to do) or totally (at the very end).
2955 size_t target_size;
2956 if (partially) {
2957 target_size = MIN2((size_t)_task_queue->max_elems()/3, GCDrainStackTargetSize);
2958 } else {
2959 target_size = 0;
2960 }
2961
2962 if (_task_queue->size() > target_size) {
2963 oop obj;
2964 bool ret = _task_queue->pop_local(obj);
2965 while (ret) {
2966 assert(_g1h->is_in_g1_reserved((HeapWord*) obj), "invariant" );
2967 assert(!_g1h->is_on_master_free_list(
2968 _g1h->heap_region_containing((HeapWord*) obj)), "invariant");
2969
2970 scan_object(obj);
2971
2972 if (_task_queue->size() <= target_size || has_aborted()) {
2973 ret = false;
2974 } else {
2975 ret = _task_queue->pop_local(obj);
2976 }
2977 }
2978 }
2979 }
2980
2981 void G1CMTask::drain_global_stack(bool partially) {
2982 if (has_aborted()) return;
2983
2984 // We have a policy to drain the local queue before we attempt to
2985 // drain the global stack.
2986 assert(partially || _task_queue->size() == 0, "invariant");
2987
2988 // Decide what the target size is, depending whether we're going to
2989 // drain it partially (so that other tasks can steal if they run out
2990 // of things to do) or totally (at the very end). Notice that,
2991 // because we move entries from the global stack in chunks or
2992 // because another task might be doing the same, we might in fact
2993 // drop below the target. But, this is not a problem.
2994 size_t target_size;
2995 if (partially) {
2996 target_size = _cm->partial_mark_stack_size_target();
2997 } else {
2998 target_size = 0;
2999 }
3000
3001 if (_cm->mark_stack_size() > target_size) {
3002 while (!has_aborted() && _cm->mark_stack_size() > target_size) {
3003 get_entries_from_global_stack();
3004 drain_local_queue(partially);
3005 }
3006 }
3007 }
3008
3009 // SATB Queue has several assumptions on whether to call the par or
3010 // non-par versions of the methods. this is why some of the code is
3011 // replicated. We should really get rid of the single-threaded version
3012 // of the code to simplify things.
3013 void G1CMTask::drain_satb_buffers() {
3014 if (has_aborted()) return;
3015
3016 // We set this so that the regular clock knows that we're in the
3017 // middle of draining buffers and doesn't set the abort flag when it
3018 // notices that SATB buffers are available for draining. It'd be
3019 // very counter productive if it did that. :-)
3020 _draining_satb_buffers = true;
3021
3022 G1CMSATBBufferClosure satb_cl(this, _g1h);
3023 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
3024
3025 // This keeps claiming and applying the closure to completed buffers
3026 // until we run out of buffers or we need to abort.
3027 while (!has_aborted() &&
3028 satb_mq_set.apply_closure_to_completed_buffer(&satb_cl)) {
3029 regular_clock_call();
3030 }
3031
3032 _draining_satb_buffers = false;
3033
3034 assert(has_aborted() ||
3035 concurrent() ||
3036 satb_mq_set.completed_buffers_num() == 0, "invariant");
3037
3038 // again, this was a potentially expensive operation, decrease the
3039 // limits to get the regular clock call early
3040 decrease_limits();
3041 }
3042
3043 void G1CMTask::print_stats() {
3044 log_debug(gc, stats)("Marking Stats, task = %u, calls = %d",
3045 _worker_id, _calls);
3046 log_debug(gc, stats)(" Elapsed time = %1.2lfms, Termination time = %1.2lfms",
3047 _elapsed_time_ms, _termination_time_ms);
3048 log_debug(gc, stats)(" Step Times (cum): num = %d, avg = %1.2lfms, sd = %1.2lfms",
3049 _step_times_ms.num(), _step_times_ms.avg(),
3050 _step_times_ms.sd());
3051 log_debug(gc, stats)(" max = %1.2lfms, total = %1.2lfms",
3052 _step_times_ms.maximum(), _step_times_ms.sum());
3053 }
3054
3055 bool G1ConcurrentMark::try_stealing(uint worker_id, int* hash_seed, oop& obj) {
3056 return _task_queues->steal(worker_id, hash_seed, obj);
3057 }
3058
3059 /*****************************************************************************
3060
3061 The do_marking_step(time_target_ms, ...) method is the building
3062 block of the parallel marking framework. It can be called in parallel
3063 with other invocations of do_marking_step() on different tasks
3064 (but only one per task, obviously) and concurrently with the
3065 mutator threads, or during remark, hence it eliminates the need
3066 for two versions of the code. When called during remark, it will
3067 pick up from where the task left off during the concurrent marking
3068 phase. Interestingly, tasks are also claimable during evacuation
3069 pauses too, since do_marking_step() ensures that it aborts before
3070 it needs to yield.
3071
3072 The data structures that it uses to do marking work are the
3073 following:
3074
3075 (1) Marking Bitmap. If there are gray objects that appear only
3076 on the bitmap (this happens either when dealing with an overflow
3077 or when the initial marking phase has simply marked the roots
3078 and didn't push them on the stack), then tasks claim heap
3079 regions whose bitmap they then scan to find gray objects. A
3080 global finger indicates where the end of the last claimed region
3081 is. A local finger indicates how far into the region a task has
3082 scanned. The two fingers are used to determine how to gray an
3083 object (i.e. whether simply marking it is OK, as it will be
3084 visited by a task in the future, or whether it needs to be also
3085 pushed on a stack).
3086
3087 (2) Local Queue. The local queue of the task which is accessed
3088 reasonably efficiently by the task. Other tasks can steal from
3089 it when they run out of work. Throughout the marking phase, a
3090 task attempts to keep its local queue short but not totally
3091 empty, so that entries are available for stealing by other
3092 tasks. Only when there is no more work, a task will totally
3093 drain its local queue.
3094
3095 (3) Global Mark Stack. This handles local queue overflow. During
3096 marking only sets of entries are moved between it and the local
3097 queues, as access to it requires a mutex and more fine-grain
3098 interaction with it which might cause contention. If it
3099 overflows, then the marking phase should restart and iterate
3100 over the bitmap to identify gray objects. Throughout the marking
3101 phase, tasks attempt to keep the global mark stack at a small
3102 length but not totally empty, so that entries are available for
3103 popping by other tasks. Only when there is no more work, tasks
3104 will totally drain the global mark stack.
3105
3106 (4) SATB Buffer Queue. This is where completed SATB buffers are
3107 made available. Buffers are regularly removed from this queue
3108 and scanned for roots, so that the queue doesn't get too
3109 long. During remark, all completed buffers are processed, as
3110 well as the filled in parts of any uncompleted buffers.
3111
3112 The do_marking_step() method tries to abort when the time target
3113 has been reached. There are a few other cases when the
3114 do_marking_step() method also aborts:
3115
3116 (1) When the marking phase has been aborted (after a Full GC).
3117
3118 (2) When a global overflow (on the global stack) has been
3119 triggered. Before the task aborts, it will actually sync up with
3120 the other tasks to ensure that all the marking data structures
3121 (local queues, stacks, fingers etc.) are re-initialized so that
3122 when do_marking_step() completes, the marking phase can
3123 immediately restart.
3124
3125 (3) When enough completed SATB buffers are available. The
3126 do_marking_step() method only tries to drain SATB buffers right
3127 at the beginning. So, if enough buffers are available, the
3128 marking step aborts and the SATB buffers are processed at
3129 the beginning of the next invocation.
3130
3131 (4) To yield. when we have to yield then we abort and yield
3132 right at the end of do_marking_step(). This saves us from a lot
3133 of hassle as, by yielding we might allow a Full GC. If this
3134 happens then objects will be compacted underneath our feet, the
3135 heap might shrink, etc. We save checking for this by just
3136 aborting and doing the yield right at the end.
3137
3138 From the above it follows that the do_marking_step() method should
3139 be called in a loop (or, otherwise, regularly) until it completes.
3140
3141 If a marking step completes without its has_aborted() flag being
3142 true, it means it has completed the current marking phase (and
3143 also all other marking tasks have done so and have all synced up).
3144
3145 A method called regular_clock_call() is invoked "regularly" (in
3146 sub ms intervals) throughout marking. It is this clock method that
3147 checks all the abort conditions which were mentioned above and
3148 decides when the task should abort. A work-based scheme is used to
3149 trigger this clock method: when the number of object words the
3150 marking phase has scanned or the number of references the marking
3151 phase has visited reach a given limit. Additional invocations to
3152 the method clock have been planted in a few other strategic places
3153 too. The initial reason for the clock method was to avoid calling
3154 vtime too regularly, as it is quite expensive. So, once it was in
3155 place, it was natural to piggy-back all the other conditions on it
3156 too and not constantly check them throughout the code.
3157
3158 If do_termination is true then do_marking_step will enter its
3159 termination protocol.
3160
3161 The value of is_serial must be true when do_marking_step is being
3162 called serially (i.e. by the VMThread) and do_marking_step should
3163 skip any synchronization in the termination and overflow code.
3164 Examples include the serial remark code and the serial reference
3165 processing closures.
3166
3167 The value of is_serial must be false when do_marking_step is
3168 being called by any of the worker threads in a work gang.
3169 Examples include the concurrent marking code (CMMarkingTask),
3170 the MT remark code, and the MT reference processing closures.
3171
3172 *****************************************************************************/
3173
3174 void G1CMTask::do_marking_step(double time_target_ms,
3175 bool do_termination,
3176 bool is_serial) {
3177 assert(time_target_ms >= 1.0, "minimum granularity is 1ms");
3178 assert(concurrent() == _cm->concurrent(), "they should be the same");
3179
3180 G1CollectorPolicy* g1_policy = _g1h->g1_policy();
3181 assert(_task_queues != NULL, "invariant");
3182 assert(_task_queue != NULL, "invariant");
3183 assert(_task_queues->queue(_worker_id) == _task_queue, "invariant");
3184
3185 assert(!_claimed,
3186 "only one thread should claim this task at any one time");
3187
3188 // OK, this doesn't safeguard again all possible scenarios, as it is
3189 // possible for two threads to set the _claimed flag at the same
3190 // time. But it is only for debugging purposes anyway and it will
3191 // catch most problems.
3192 _claimed = true;
3193
3194 _start_time_ms = os::elapsedVTime() * 1000.0;
3195
3196 // If do_stealing is true then do_marking_step will attempt to
3197 // steal work from the other G1CMTasks. It only makes sense to
3198 // enable stealing when the termination protocol is enabled
3199 // and do_marking_step() is not being called serially.
3200 bool do_stealing = do_termination && !is_serial;
3201
3202 double diff_prediction_ms = _g1h->g1_policy()->predictor().get_new_prediction(&_marking_step_diffs_ms);
3203 _time_target_ms = time_target_ms - diff_prediction_ms;
3204
3205 // set up the variables that are used in the work-based scheme to
3206 // call the regular clock method
3207 _words_scanned = 0;
3208 _refs_reached = 0;
3209 recalculate_limits();
3210
3211 // clear all flags
3212 clear_has_aborted();
3213 _has_timed_out = false;
3214 _draining_satb_buffers = false;
3215
3216 ++_calls;
3217
3218 // Set up the bitmap and oop closures. Anything that uses them is
3219 // eventually called from this method, so it is OK to allocate these
3220 // statically.
3221 G1CMBitMapClosure bitmap_closure(this, _cm, _nextMarkBitMap);
3222 G1CMOopClosure cm_oop_closure(_g1h, _cm, this);
3223 set_cm_oop_closure(&cm_oop_closure);
3224
3225 if (_cm->has_overflown()) {
3226 // This can happen if the mark stack overflows during a GC pause
3227 // and this task, after a yield point, restarts. We have to abort
3228 // as we need to get into the overflow protocol which happens
3229 // right at the end of this task.
3230 set_has_aborted();
3231 }
3232
3233 // First drain any available SATB buffers. After this, we will not
3234 // look at SATB buffers before the next invocation of this method.
3235 // If enough completed SATB buffers are queued up, the regular clock
3236 // will abort this task so that it restarts.
3237 drain_satb_buffers();
3238 // ...then partially drain the local queue and the global stack
3239 drain_local_queue(true);
3240 drain_global_stack(true);
3241
3242 do {
3243 if (!has_aborted() && _curr_region != NULL) {
3244 // This means that we're already holding on to a region.
3245 assert(_finger != NULL, "if region is not NULL, then the finger "
3246 "should not be NULL either");
3247
3248 // We might have restarted this task after an evacuation pause
3249 // which might have evacuated the region we're holding on to
3250 // underneath our feet. Let's read its limit again to make sure
3251 // that we do not iterate over a region of the heap that
3252 // contains garbage (update_region_limit() will also move
3253 // _finger to the start of the region if it is found empty).
3254 update_region_limit();
3255 // We will start from _finger not from the start of the region,
3256 // as we might be restarting this task after aborting half-way
3257 // through scanning this region. In this case, _finger points to
3258 // the address where we last found a marked object. If this is a
3259 // fresh region, _finger points to start().
3260 MemRegion mr = MemRegion(_finger, _region_limit);
3261
3262 assert(!_curr_region->is_humongous() || mr.start() == _curr_region->bottom(),
3263 "humongous regions should go around loop once only");
3264
3265 // Some special cases:
3266 // If the memory region is empty, we can just give up the region.
3267 // If the current region is humongous then we only need to check
3268 // the bitmap for the bit associated with the start of the object,
3269 // scan the object if it's live, and give up the region.
3270 // Otherwise, let's iterate over the bitmap of the part of the region
3271 // that is left.
3272 // If the iteration is successful, give up the region.
3273 if (mr.is_empty()) {
3274 giveup_current_region();
3275 regular_clock_call();
3276 } else if (_curr_region->is_humongous() && mr.start() == _curr_region->bottom()) {
3277 if (_nextMarkBitMap->isMarked(mr.start())) {
3278 // The object is marked - apply the closure
3279 BitMap::idx_t offset = _nextMarkBitMap->heapWordToOffset(mr.start());
3280 bitmap_closure.do_bit(offset);
3281 }
3282 // Even if this task aborted while scanning the humongous object
3283 // we can (and should) give up the current region.
3284 giveup_current_region();
3285 regular_clock_call();
3286 } else if (_nextMarkBitMap->iterate(&bitmap_closure, mr)) {
3287 giveup_current_region();
3288 regular_clock_call();
3289 } else {
3290 assert(has_aborted(), "currently the only way to do so");
3291 // The only way to abort the bitmap iteration is to return
3292 // false from the do_bit() method. However, inside the
3293 // do_bit() method we move the _finger to point to the
3294 // object currently being looked at. So, if we bail out, we
3295 // have definitely set _finger to something non-null.
3296 assert(_finger != NULL, "invariant");
3297
3298 // Region iteration was actually aborted. So now _finger
3299 // points to the address of the object we last scanned. If we
3300 // leave it there, when we restart this task, we will rescan
3301 // the object. It is easy to avoid this. We move the finger by
3302 // enough to point to the next possible object header (the
3303 // bitmap knows by how much we need to move it as it knows its
3304 // granularity).
3305 assert(_finger < _region_limit, "invariant");
3306 HeapWord* new_finger = _nextMarkBitMap->nextObject(_finger);
3307 // Check if bitmap iteration was aborted while scanning the last object
3308 if (new_finger >= _region_limit) {
3309 giveup_current_region();
3310 } else {
3311 move_finger_to(new_finger);
3312 }
3313 }
3314 }
3315 // At this point we have either completed iterating over the
3316 // region we were holding on to, or we have aborted.
3317
3318 // We then partially drain the local queue and the global stack.
3319 // (Do we really need this?)
3320 drain_local_queue(true);
3321 drain_global_stack(true);
3322
3323 // Read the note on the claim_region() method on why it might
3324 // return NULL with potentially more regions available for
3325 // claiming and why we have to check out_of_regions() to determine
3326 // whether we're done or not.
3327 while (!has_aborted() && _curr_region == NULL && !_cm->out_of_regions()) {
3328 // We are going to try to claim a new region. We should have
3329 // given up on the previous one.
3330 // Separated the asserts so that we know which one fires.
3331 assert(_curr_region == NULL, "invariant");
3332 assert(_finger == NULL, "invariant");
3333 assert(_region_limit == NULL, "invariant");
3334 HeapRegion* claimed_region = _cm->claim_region(_worker_id);
3335 if (claimed_region != NULL) {
3336 // Yes, we managed to claim one
3337 setup_for_region(claimed_region);
3338 assert(_curr_region == claimed_region, "invariant");
3339 }
3340 // It is important to call the regular clock here. It might take
3341 // a while to claim a region if, for example, we hit a large
3342 // block of empty regions. So we need to call the regular clock
3343 // method once round the loop to make sure it's called
3344 // frequently enough.
3345 regular_clock_call();
3346 }
3347
3348 if (!has_aborted() && _curr_region == NULL) {
3349 assert(_cm->out_of_regions(),
3350 "at this point we should be out of regions");
3351 }
3352 } while ( _curr_region != NULL && !has_aborted());
3353
3354 if (!has_aborted()) {
3355 // We cannot check whether the global stack is empty, since other
3356 // tasks might be pushing objects to it concurrently.
3357 assert(_cm->out_of_regions(),
3358 "at this point we should be out of regions");
3359 // Try to reduce the number of available SATB buffers so that
3360 // remark has less work to do.
3361 drain_satb_buffers();
3362 }
3363
3364 // Since we've done everything else, we can now totally drain the
3365 // local queue and global stack.
3366 drain_local_queue(false);
3367 drain_global_stack(false);
3368
3369 // Attempt at work stealing from other task's queues.
3370 if (do_stealing && !has_aborted()) {
3371 // We have not aborted. This means that we have finished all that
3372 // we could. Let's try to do some stealing...
3373
3374 // We cannot check whether the global stack is empty, since other
3375 // tasks might be pushing objects to it concurrently.
3376 assert(_cm->out_of_regions() && _task_queue->size() == 0,
3377 "only way to reach here");
3378 while (!has_aborted()) {
3379 oop obj;
3380 if (_cm->try_stealing(_worker_id, &_hash_seed, obj)) {
3381 assert(_nextMarkBitMap->isMarked((HeapWord*) obj),
3382 "any stolen object should be marked");
3383 scan_object(obj);
3384
3385 // And since we're towards the end, let's totally drain the
3386 // local queue and global stack.
3387 drain_local_queue(false);
3388 drain_global_stack(false);
3389 } else {
3390 break;
3391 }
3392 }
3393 }
3394
3395 // We still haven't aborted. Now, let's try to get into the
3396 // termination protocol.
3397 if (do_termination && !has_aborted()) {
3398 // We cannot check whether the global stack is empty, since other
3399 // tasks might be concurrently pushing objects on it.
3400 // Separated the asserts so that we know which one fires.
3401 assert(_cm->out_of_regions(), "only way to reach here");
3402 assert(_task_queue->size() == 0, "only way to reach here");
3403 _termination_start_time_ms = os::elapsedVTime() * 1000.0;
3404
3405 // The G1CMTask class also extends the TerminatorTerminator class,
3406 // hence its should_exit_termination() method will also decide
3407 // whether to exit the termination protocol or not.
3408 bool finished = (is_serial ||
3409 _cm->terminator()->offer_termination(this));
3410 double termination_end_time_ms = os::elapsedVTime() * 1000.0;
3411 _termination_time_ms +=
3412 termination_end_time_ms - _termination_start_time_ms;
3413
3414 if (finished) {
3415 // We're all done.
3416
3417 if (_worker_id == 0) {
3418 // let's allow task 0 to do this
3419 if (concurrent()) {
3420 assert(_cm->concurrent_marking_in_progress(), "invariant");
3421 // we need to set this to false before the next
3422 // safepoint. This way we ensure that the marking phase
3423 // doesn't observe any more heap expansions.
3424 _cm->clear_concurrent_marking_in_progress();
3425 }
3426 }
3427
3428 // We can now guarantee that the global stack is empty, since
3429 // all other tasks have finished. We separated the guarantees so
3430 // that, if a condition is false, we can immediately find out
3431 // which one.
3432 guarantee(_cm->out_of_regions(), "only way to reach here");
3433 guarantee(_cm->mark_stack_empty(), "only way to reach here");
3434 guarantee(_task_queue->size() == 0, "only way to reach here");
3435 guarantee(!_cm->has_overflown(), "only way to reach here");
3436 guarantee(!_cm->mark_stack_overflow(), "only way to reach here");
3437 } else {
3438 // Apparently there's more work to do. Let's abort this task. It
3439 // will restart it and we can hopefully find more things to do.
3440 set_has_aborted();
3441 }
3442 }
3443
3444 // Mainly for debugging purposes to make sure that a pointer to the
3445 // closure which was statically allocated in this frame doesn't
3446 // escape it by accident.
3447 set_cm_oop_closure(NULL);
3448 double end_time_ms = os::elapsedVTime() * 1000.0;
3449 double elapsed_time_ms = end_time_ms - _start_time_ms;
3450 // Update the step history.
3451 _step_times_ms.add(elapsed_time_ms);
3452
3453 if (has_aborted()) {
3454 // The task was aborted for some reason.
3455 if (_has_timed_out) {
3456 double diff_ms = elapsed_time_ms - _time_target_ms;
3457 // Keep statistics of how well we did with respect to hitting
3458 // our target only if we actually timed out (if we aborted for
3459 // other reasons, then the results might get skewed).
3460 _marking_step_diffs_ms.add(diff_ms);
3461 }
3462
3463 if (_cm->has_overflown()) {
3464 // This is the interesting one. We aborted because a global
3465 // overflow was raised. This means we have to restart the
3466 // marking phase and start iterating over regions. However, in
3467 // order to do this we have to make sure that all tasks stop
3468 // what they are doing and re-initialize in a safe manner. We
3469 // will achieve this with the use of two barrier sync points.
3470
3471 if (!is_serial) {
3472 // We only need to enter the sync barrier if being called
3473 // from a parallel context
3474 _cm->enter_first_sync_barrier(_worker_id);
3475
3476 // When we exit this sync barrier we know that all tasks have
3477 // stopped doing marking work. So, it's now safe to
3478 // re-initialize our data structures. At the end of this method,
3479 // task 0 will clear the global data structures.
3480 }
3481
3482 // We clear the local state of this task...
3483 clear_region_fields();
3484
3485 if (!is_serial) {
3486 // ...and enter the second barrier.
3487 _cm->enter_second_sync_barrier(_worker_id);
3488 }
3489 // At this point, if we're during the concurrent phase of
3490 // marking, everything has been re-initialized and we're
3491 // ready to restart.
3492 }
3493 }
3494
3495 _claimed = false;
3496 }
3497
3498 G1CMTask::G1CMTask(uint worker_id,
3499 G1ConcurrentMark* cm,
3500 size_t* marked_bytes,
3501 BitMap* card_bm,
3502 G1CMTaskQueue* task_queue,
3503 G1CMTaskQueueSet* task_queues)
3504 : _g1h(G1CollectedHeap::heap()),
3505 _worker_id(worker_id), _cm(cm),
3506 _claimed(false),
3507 _nextMarkBitMap(NULL), _hash_seed(17),
3508 _task_queue(task_queue),
3509 _task_queues(task_queues),
3510 _cm_oop_closure(NULL),
3511 _marked_bytes_array(marked_bytes),
3512 _card_bm(card_bm) {
3513 guarantee(task_queue != NULL, "invariant");
3514 guarantee(task_queues != NULL, "invariant");
3515
3516 _marking_step_diffs_ms.add(0.5);
3517 }
3518
3519 // These are formatting macros that are used below to ensure
3520 // consistent formatting. The *_H_* versions are used to format the
3521 // header for a particular value and they should be kept consistent
3522 // with the corresponding macro. Also note that most of the macros add
3523 // the necessary white space (as a prefix) which makes them a bit
3524 // easier to compose.
3525
3526 // All the output lines are prefixed with this string to be able to
3527 // identify them easily in a large log file.
3528 #define G1PPRL_LINE_PREFIX "###"
3529
3530 #define G1PPRL_ADDR_BASE_FORMAT " " PTR_FORMAT "-" PTR_FORMAT
3531 #ifdef _LP64
3532 #define G1PPRL_ADDR_BASE_H_FORMAT " %37s"
3533 #else // _LP64
3534 #define G1PPRL_ADDR_BASE_H_FORMAT " %21s"
3535 #endif // _LP64
3536
3537 // For per-region info
3538 #define G1PPRL_TYPE_FORMAT " %-4s"
3539 #define G1PPRL_TYPE_H_FORMAT " %4s"
3540 #define G1PPRL_BYTE_FORMAT " " SIZE_FORMAT_W(9)
3541 #define G1PPRL_BYTE_H_FORMAT " %9s"
3542 #define G1PPRL_DOUBLE_FORMAT " %14.1f"
3543 #define G1PPRL_DOUBLE_H_FORMAT " %14s"
3544
3545 // For summary info
3546 #define G1PPRL_SUM_ADDR_FORMAT(tag) " " tag ":" G1PPRL_ADDR_BASE_FORMAT
3547 #define G1PPRL_SUM_BYTE_FORMAT(tag) " " tag ": " SIZE_FORMAT
3548 #define G1PPRL_SUM_MB_FORMAT(tag) " " tag ": %1.2f MB"
3549 #define G1PPRL_SUM_MB_PERC_FORMAT(tag) G1PPRL_SUM_MB_FORMAT(tag) " / %1.2f %%"
3550
3551 G1PrintRegionLivenessInfoClosure::
3552 G1PrintRegionLivenessInfoClosure(const char* phase_name)
3553 : _total_used_bytes(0), _total_capacity_bytes(0),
3554 _total_prev_live_bytes(0), _total_next_live_bytes(0),
3555 _hum_used_bytes(0), _hum_capacity_bytes(0),
3556 _hum_prev_live_bytes(0), _hum_next_live_bytes(0),
3557 _total_remset_bytes(0), _total_strong_code_roots_bytes(0) {
3558 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3559 MemRegion g1_reserved = g1h->g1_reserved();
3560 double now = os::elapsedTime();
3561
3562 // Print the header of the output.
3563 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX" PHASE %s @ %1.3f", phase_name, now);
3564 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX" HEAP"
3565 G1PPRL_SUM_ADDR_FORMAT("reserved")
3566 G1PPRL_SUM_BYTE_FORMAT("region-size"),
3567 p2i(g1_reserved.start()), p2i(g1_reserved.end()),
3568 HeapRegion::GrainBytes);
3569 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX);
3570 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX
3571 G1PPRL_TYPE_H_FORMAT
3572 G1PPRL_ADDR_BASE_H_FORMAT
3573 G1PPRL_BYTE_H_FORMAT
3574 G1PPRL_BYTE_H_FORMAT
3575 G1PPRL_BYTE_H_FORMAT
3576 G1PPRL_DOUBLE_H_FORMAT
3577 G1PPRL_BYTE_H_FORMAT
3578 G1PPRL_BYTE_H_FORMAT,
3579 "type", "address-range",
3580 "used", "prev-live", "next-live", "gc-eff",
3581 "remset", "code-roots");
3582 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX
3583 G1PPRL_TYPE_H_FORMAT
3584 G1PPRL_ADDR_BASE_H_FORMAT
3585 G1PPRL_BYTE_H_FORMAT
3586 G1PPRL_BYTE_H_FORMAT
3587 G1PPRL_BYTE_H_FORMAT
3588 G1PPRL_DOUBLE_H_FORMAT
3589 G1PPRL_BYTE_H_FORMAT
3590 G1PPRL_BYTE_H_FORMAT,
3591 "", "",
3592 "(bytes)", "(bytes)", "(bytes)", "(bytes/ms)",
3593 "(bytes)", "(bytes)");
3594 }
3595
3596 // It takes as a parameter a reference to one of the _hum_* fields, it
3597 // deduces the corresponding value for a region in a humongous region
3598 // series (either the region size, or what's left if the _hum_* field
3599 // is < the region size), and updates the _hum_* field accordingly.
3600 size_t G1PrintRegionLivenessInfoClosure::get_hum_bytes(size_t* hum_bytes) {
3601 size_t bytes = 0;
3602 // The > 0 check is to deal with the prev and next live bytes which
3603 // could be 0.
3604 if (*hum_bytes > 0) {
3605 bytes = MIN2(HeapRegion::GrainBytes, *hum_bytes);
3606 *hum_bytes -= bytes;
3607 }
3608 return bytes;
3609 }
3610
3611 // It deduces the values for a region in a humongous region series
3612 // from the _hum_* fields and updates those accordingly. It assumes
3613 // that that _hum_* fields have already been set up from the "starts
3614 // humongous" region and we visit the regions in address order.
3615 void G1PrintRegionLivenessInfoClosure::get_hum_bytes(size_t* used_bytes,
3616 size_t* capacity_bytes,
3617 size_t* prev_live_bytes,
3618 size_t* next_live_bytes) {
3619 assert(_hum_used_bytes > 0 && _hum_capacity_bytes > 0, "pre-condition");
3620 *used_bytes = get_hum_bytes(&_hum_used_bytes);
3621 *capacity_bytes = get_hum_bytes(&_hum_capacity_bytes);
3622 *prev_live_bytes = get_hum_bytes(&_hum_prev_live_bytes);
3623 *next_live_bytes = get_hum_bytes(&_hum_next_live_bytes);
3624 }
3625
3626 bool G1PrintRegionLivenessInfoClosure::doHeapRegion(HeapRegion* r) {
3627 const char* type = r->get_type_str();
3628 HeapWord* bottom = r->bottom();
3629 HeapWord* end = r->end();
3630 size_t capacity_bytes = r->capacity();
3631 size_t used_bytes = r->used();
3632 size_t prev_live_bytes = r->live_bytes();
3633 size_t next_live_bytes = r->next_live_bytes();
3634 double gc_eff = r->gc_efficiency();
3635 size_t remset_bytes = r->rem_set()->mem_size();
3636 size_t strong_code_roots_bytes = r->rem_set()->strong_code_roots_mem_size();
3637
3638 if (r->is_starts_humongous()) {
3639 assert(_hum_used_bytes == 0 && _hum_capacity_bytes == 0 &&
3640 _hum_prev_live_bytes == 0 && _hum_next_live_bytes == 0,
3641 "they should have been zeroed after the last time we used them");
3642 // Set up the _hum_* fields.
3643 _hum_capacity_bytes = capacity_bytes;
3644 _hum_used_bytes = used_bytes;
3645 _hum_prev_live_bytes = prev_live_bytes;
3646 _hum_next_live_bytes = next_live_bytes;
3647 get_hum_bytes(&used_bytes, &capacity_bytes,
3648 &prev_live_bytes, &next_live_bytes);
3649 end = bottom + HeapRegion::GrainWords;
3650 } else if (r->is_continues_humongous()) {
3651 get_hum_bytes(&used_bytes, &capacity_bytes,
3652 &prev_live_bytes, &next_live_bytes);
3653 assert(end == bottom + HeapRegion::GrainWords, "invariant");
3654 }
3655
3656 _total_used_bytes += used_bytes;
3657 _total_capacity_bytes += capacity_bytes;
3658 _total_prev_live_bytes += prev_live_bytes;
3659 _total_next_live_bytes += next_live_bytes;
3660 _total_remset_bytes += remset_bytes;
3661 _total_strong_code_roots_bytes += strong_code_roots_bytes;
3662
3663 // Print a line for this particular region.
3664 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX
3665 G1PPRL_TYPE_FORMAT
3666 G1PPRL_ADDR_BASE_FORMAT
3667 G1PPRL_BYTE_FORMAT
3668 G1PPRL_BYTE_FORMAT
3669 G1PPRL_BYTE_FORMAT
3670 G1PPRL_DOUBLE_FORMAT
3671 G1PPRL_BYTE_FORMAT
3672 G1PPRL_BYTE_FORMAT,
3673 type, p2i(bottom), p2i(end),
3674 used_bytes, prev_live_bytes, next_live_bytes, gc_eff,
3675 remset_bytes, strong_code_roots_bytes);
3676
3677 return false;
3678 }
3679
3680 G1PrintRegionLivenessInfoClosure::~G1PrintRegionLivenessInfoClosure() {
3681 // add static memory usages to remembered set sizes
3682 _total_remset_bytes += HeapRegionRemSet::fl_mem_size() + HeapRegionRemSet::static_mem_size();
3683 // Print the footer of the output.
3684 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX);
3685 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX
3686 " SUMMARY"
3687 G1PPRL_SUM_MB_FORMAT("capacity")
3688 G1PPRL_SUM_MB_PERC_FORMAT("used")
3689 G1PPRL_SUM_MB_PERC_FORMAT("prev-live")
3690 G1PPRL_SUM_MB_PERC_FORMAT("next-live")
3691 G1PPRL_SUM_MB_FORMAT("remset")
3692 G1PPRL_SUM_MB_FORMAT("code-roots"),
3693 bytes_to_mb(_total_capacity_bytes),
3694 bytes_to_mb(_total_used_bytes),
3695 perc(_total_used_bytes, _total_capacity_bytes),
3696 bytes_to_mb(_total_prev_live_bytes),
3697 perc(_total_prev_live_bytes, _total_capacity_bytes),
3698 bytes_to_mb(_total_next_live_bytes),
3699 perc(_total_next_live_bytes, _total_capacity_bytes),
3700 bytes_to_mb(_total_remset_bytes),
3701 bytes_to_mb(_total_strong_code_roots_bytes));
3702 }