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