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