1 /* 2 * Copyright (c) 2001, 2014, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "classfile/metadataOnStackMark.hpp" 27 #include "classfile/symbolTable.hpp" 28 #include "code/codeCache.hpp" 29 #include "gc_implementation/g1/concurrentMark.inline.hpp" 30 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp" 31 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp" 32 #include "gc_implementation/g1/g1CollectorPolicy.hpp" 33 #include "gc_implementation/g1/g1ErgoVerbose.hpp" 34 #include "gc_implementation/g1/g1Log.hpp" 35 #include "gc_implementation/g1/g1OopClosures.inline.hpp" 36 #include "gc_implementation/g1/g1RemSet.hpp" 37 #include "gc_implementation/g1/heapRegion.inline.hpp" 38 #include "gc_implementation/g1/heapRegionManager.inline.hpp" 39 #include "gc_implementation/g1/heapRegionRemSet.hpp" 40 #include "gc_implementation/g1/heapRegionSet.inline.hpp" 41 #include "gc_implementation/shared/vmGCOperations.hpp" 42 #include "gc_implementation/shared/gcTimer.hpp" 43 #include "gc_implementation/shared/gcTrace.hpp" 44 #include "gc_implementation/shared/gcTraceTime.hpp" 45 #include "memory/allocation.hpp" 46 #include "memory/genOopClosures.inline.hpp" 47 #include "memory/referencePolicy.hpp" 48 #include "memory/resourceArea.hpp" 49 #include "oops/oop.inline.hpp" 50 #include "runtime/handles.inline.hpp" 51 #include "runtime/java.hpp" 52 #include "runtime/prefetch.inline.hpp" 53 #include "services/memTracker.hpp" 54 55 // Concurrent marking bit map wrapper 56 57 CMBitMapRO::CMBitMapRO(int shifter) : 58 _bm(), 59 _shifter(shifter) { 60 _bmStartWord = 0; 61 _bmWordSize = 0; 62 } 63 64 HeapWord* CMBitMapRO::getNextMarkedWordAddress(const HeapWord* addr, 65 const HeapWord* limit) const { 66 // First we must round addr *up* to a possible object boundary. 67 addr = (HeapWord*)align_size_up((intptr_t)addr, 68 HeapWordSize << _shifter); 69 size_t addrOffset = heapWordToOffset(addr); 70 if (limit == NULL) { 71 limit = _bmStartWord + _bmWordSize; 72 } 73 size_t limitOffset = heapWordToOffset(limit); 74 size_t nextOffset = _bm.get_next_one_offset(addrOffset, limitOffset); 75 HeapWord* nextAddr = offsetToHeapWord(nextOffset); 76 assert(nextAddr >= addr, "get_next_one postcondition"); 77 assert(nextAddr == limit || isMarked(nextAddr), 78 "get_next_one postcondition"); 79 return nextAddr; 80 } 81 82 HeapWord* CMBitMapRO::getNextUnmarkedWordAddress(const HeapWord* addr, 83 const HeapWord* limit) const { 84 size_t addrOffset = heapWordToOffset(addr); 85 if (limit == NULL) { 86 limit = _bmStartWord + _bmWordSize; 87 } 88 size_t limitOffset = heapWordToOffset(limit); 89 size_t nextOffset = _bm.get_next_zero_offset(addrOffset, limitOffset); 90 HeapWord* nextAddr = offsetToHeapWord(nextOffset); 91 assert(nextAddr >= addr, "get_next_one postcondition"); 92 assert(nextAddr == limit || !isMarked(nextAddr), 93 "get_next_one postcondition"); 94 return nextAddr; 95 } 96 97 int CMBitMapRO::heapWordDiffToOffsetDiff(size_t diff) const { 98 assert((diff & ((1 << _shifter) - 1)) == 0, "argument check"); 99 return (int) (diff >> _shifter); 100 } 101 102 #ifndef PRODUCT 103 bool CMBitMapRO::covers(MemRegion heap_rs) const { 104 // assert(_bm.map() == _virtual_space.low(), "map inconsistency"); 105 assert(((size_t)_bm.size() * ((size_t)1 << _shifter)) == _bmWordSize, 106 "size inconsistency"); 107 return _bmStartWord == (HeapWord*)(heap_rs.start()) && 108 _bmWordSize == heap_rs.word_size(); 109 } 110 #endif 111 112 void CMBitMapRO::print_on_error(outputStream* st, const char* prefix) const { 113 _bm.print_on_error(st, prefix); 114 } 115 116 size_t CMBitMap::compute_size(size_t heap_size) { 117 return ReservedSpace::allocation_align_size_up(heap_size / mark_distance()); 118 } 119 120 size_t CMBitMap::mark_distance() { 121 return MinObjAlignmentInBytes * BitsPerByte; 122 } 123 124 void CMBitMap::initialize(MemRegion heap, G1RegionToSpaceMapper* storage) { 125 _bmStartWord = heap.start(); 126 _bmWordSize = heap.word_size(); 127 128 _bm.set_map((BitMap::bm_word_t*) storage->reserved().start()); 129 _bm.set_size(_bmWordSize >> _shifter); 130 131 storage->set_mapping_changed_listener(&_listener); 132 } 133 134 void CMBitMapMappingChangedListener::on_commit(uint start_region, size_t num_regions, bool zero_filled) { 135 if (zero_filled) { 136 return; 137 } 138 // We need to clear the bitmap on commit, removing any existing information. 139 MemRegion mr(G1CollectedHeap::heap()->bottom_addr_for_region(start_region), num_regions * HeapRegion::GrainWords); 140 _bm->clearRange(mr); 141 } 142 143 // Closure used for clearing the given mark bitmap. 144 class ClearBitmapHRClosure : public HeapRegionClosure { 145 private: 146 ConcurrentMark* _cm; 147 CMBitMap* _bitmap; 148 bool _may_yield; // The closure may yield during iteration. If yielded, abort the iteration. 149 public: 150 ClearBitmapHRClosure(ConcurrentMark* cm, CMBitMap* bitmap, bool may_yield) : HeapRegionClosure(), _cm(cm), _bitmap(bitmap), _may_yield(may_yield) { 151 assert(!may_yield || cm != NULL, "CM must be non-NULL if this closure is expected to yield."); 152 } 153 154 virtual bool doHeapRegion(HeapRegion* r) { 155 size_t const chunk_size_in_words = M / HeapWordSize; 156 157 HeapWord* cur = r->bottom(); 158 HeapWord* const end = r->end(); 159 160 while (cur < end) { 161 MemRegion mr(cur, MIN2(cur + chunk_size_in_words, end)); 162 _bitmap->clearRange(mr); 163 164 cur += chunk_size_in_words; 165 166 // Abort iteration if after yielding the marking has been aborted. 167 if (_may_yield && _cm->do_yield_check() && _cm->has_aborted()) { 168 return true; 169 } 170 // Repeat the asserts from before the start of the closure. We will do them 171 // as asserts here to minimize their overhead on the product. However, we 172 // will have them as guarantees at the beginning / end of the bitmap 173 // clearing to get some checking in the product. 174 assert(!_may_yield || _cm->cmThread()->during_cycle(), "invariant"); 175 assert(!_may_yield || !G1CollectedHeap::heap()->mark_in_progress(), "invariant"); 176 } 177 178 return false; 179 } 180 }; 181 182 void CMBitMap::clearAll() { 183 ClearBitmapHRClosure cl(NULL, this, false /* may_yield */); 184 G1CollectedHeap::heap()->heap_region_iterate(&cl); 185 guarantee(cl.complete(), "Must have completed iteration."); 186 return; 187 } 188 189 void CMBitMap::markRange(MemRegion mr) { 190 mr.intersection(MemRegion(_bmStartWord, _bmWordSize)); 191 assert(!mr.is_empty(), "unexpected empty region"); 192 assert((offsetToHeapWord(heapWordToOffset(mr.end())) == 193 ((HeapWord *) mr.end())), 194 "markRange memory region end is not card aligned"); 195 // convert address range into offset range 196 _bm.at_put_range(heapWordToOffset(mr.start()), 197 heapWordToOffset(mr.end()), true); 198 } 199 200 void CMBitMap::clearRange(MemRegion mr) { 201 mr.intersection(MemRegion(_bmStartWord, _bmWordSize)); 202 assert(!mr.is_empty(), "unexpected empty region"); 203 // convert address range into offset range 204 _bm.at_put_range(heapWordToOffset(mr.start()), 205 heapWordToOffset(mr.end()), false); 206 } 207 208 MemRegion CMBitMap::getAndClearMarkedRegion(HeapWord* addr, 209 HeapWord* end_addr) { 210 HeapWord* start = getNextMarkedWordAddress(addr); 211 start = MIN2(start, end_addr); 212 HeapWord* end = getNextUnmarkedWordAddress(start); 213 end = MIN2(end, end_addr); 214 assert(start <= end, "Consistency check"); 215 MemRegion mr(start, end); 216 if (!mr.is_empty()) { 217 clearRange(mr); 218 } 219 return mr; 220 } 221 222 CMMarkStack::CMMarkStack(ConcurrentMark* cm) : 223 _base(NULL), _cm(cm) 224 #ifdef ASSERT 225 , _drain_in_progress(false) 226 , _drain_in_progress_yields(false) 227 #endif 228 {} 229 230 bool CMMarkStack::allocate(size_t capacity) { 231 // allocate a stack of the requisite depth 232 ReservedSpace rs(ReservedSpace::allocation_align_size_up(capacity * sizeof(oop))); 233 if (!rs.is_reserved()) { 234 warning("ConcurrentMark MarkStack allocation failure"); 235 return false; 236 } 237 MemTracker::record_virtual_memory_type((address)rs.base(), mtGC); 238 if (!_virtual_space.initialize(rs, rs.size())) { 239 warning("ConcurrentMark MarkStack backing store failure"); 240 // Release the virtual memory reserved for the marking stack 241 rs.release(); 242 return false; 243 } 244 assert(_virtual_space.committed_size() == rs.size(), 245 "Didn't reserve backing store for all of ConcurrentMark stack?"); 246 _base = (oop*) _virtual_space.low(); 247 setEmpty(); 248 _capacity = (jint) capacity; 249 _saved_index = -1; 250 _should_expand = false; 251 NOT_PRODUCT(_max_depth = 0); 252 return true; 253 } 254 255 void CMMarkStack::expand() { 256 // Called, during remark, if we've overflown the marking stack during marking. 257 assert(isEmpty(), "stack should been emptied while handling overflow"); 258 assert(_capacity <= (jint) MarkStackSizeMax, "stack bigger than permitted"); 259 // Clear expansion flag 260 _should_expand = false; 261 if (_capacity == (jint) MarkStackSizeMax) { 262 if (PrintGCDetails && Verbose) { 263 gclog_or_tty->print_cr(" (benign) Can't expand marking stack capacity, at max size limit"); 264 } 265 return; 266 } 267 // Double capacity if possible 268 jint new_capacity = MIN2(_capacity*2, (jint) MarkStackSizeMax); 269 // Do not give up existing stack until we have managed to 270 // get the double capacity that we desired. 271 ReservedSpace rs(ReservedSpace::allocation_align_size_up(new_capacity * 272 sizeof(oop))); 273 if (rs.is_reserved()) { 274 // Release the backing store associated with old stack 275 _virtual_space.release(); 276 // Reinitialize virtual space for new stack 277 if (!_virtual_space.initialize(rs, rs.size())) { 278 fatal("Not enough swap for expanded marking stack capacity"); 279 } 280 _base = (oop*)(_virtual_space.low()); 281 _index = 0; 282 _capacity = new_capacity; 283 } else { 284 if (PrintGCDetails && Verbose) { 285 // Failed to double capacity, continue; 286 gclog_or_tty->print(" (benign) Failed to expand marking stack capacity from " 287 SIZE_FORMAT"K to " SIZE_FORMAT"K", 288 _capacity / K, new_capacity / K); 289 } 290 } 291 } 292 293 void CMMarkStack::set_should_expand() { 294 // If we're resetting the marking state because of an 295 // marking stack overflow, record that we should, if 296 // possible, expand the stack. 297 _should_expand = _cm->has_overflown(); 298 } 299 300 CMMarkStack::~CMMarkStack() { 301 if (_base != NULL) { 302 _base = NULL; 303 _virtual_space.release(); 304 } 305 } 306 307 void CMMarkStack::par_push(oop ptr) { 308 while (true) { 309 if (isFull()) { 310 _overflow = true; 311 return; 312 } 313 // Otherwise... 314 jint index = _index; 315 jint next_index = index+1; 316 jint res = Atomic::cmpxchg(next_index, &_index, index); 317 if (res == index) { 318 _base[index] = ptr; 319 // Note that we don't maintain this atomically. We could, but it 320 // doesn't seem necessary. 321 NOT_PRODUCT(_max_depth = MAX2(_max_depth, next_index)); 322 return; 323 } 324 // Otherwise, we need to try again. 325 } 326 } 327 328 void CMMarkStack::par_adjoin_arr(oop* ptr_arr, int n) { 329 while (true) { 330 if (isFull()) { 331 _overflow = true; 332 return; 333 } 334 // Otherwise... 335 jint index = _index; 336 jint next_index = index + n; 337 if (next_index > _capacity) { 338 _overflow = true; 339 return; 340 } 341 jint res = Atomic::cmpxchg(next_index, &_index, index); 342 if (res == index) { 343 for (int i = 0; i < n; i++) { 344 int ind = index + i; 345 assert(ind < _capacity, "By overflow test above."); 346 _base[ind] = ptr_arr[i]; 347 } 348 NOT_PRODUCT(_max_depth = MAX2(_max_depth, next_index)); 349 return; 350 } 351 // Otherwise, we need to try again. 352 } 353 } 354 355 void CMMarkStack::par_push_arr(oop* ptr_arr, int n) { 356 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); 357 jint start = _index; 358 jint next_index = start + n; 359 if (next_index > _capacity) { 360 _overflow = true; 361 return; 362 } 363 // Otherwise. 364 _index = next_index; 365 for (int i = 0; i < n; i++) { 366 int ind = start + i; 367 assert(ind < _capacity, "By overflow test above."); 368 _base[ind] = ptr_arr[i]; 369 } 370 NOT_PRODUCT(_max_depth = MAX2(_max_depth, next_index)); 371 } 372 373 bool CMMarkStack::par_pop_arr(oop* ptr_arr, int max, int* n) { 374 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); 375 jint index = _index; 376 if (index == 0) { 377 *n = 0; 378 return false; 379 } else { 380 int k = MIN2(max, index); 381 jint new_ind = index - k; 382 for (int j = 0; j < k; j++) { 383 ptr_arr[j] = _base[new_ind + j]; 384 } 385 _index = new_ind; 386 *n = k; 387 return true; 388 } 389 } 390 391 template<class OopClosureClass> 392 bool CMMarkStack::drain(OopClosureClass* cl, CMBitMap* bm, bool yield_after) { 393 assert(!_drain_in_progress || !_drain_in_progress_yields || yield_after 394 || SafepointSynchronize::is_at_safepoint(), 395 "Drain recursion must be yield-safe."); 396 bool res = true; 397 debug_only(_drain_in_progress = true); 398 debug_only(_drain_in_progress_yields = yield_after); 399 while (!isEmpty()) { 400 oop newOop = pop(); 401 assert(G1CollectedHeap::heap()->is_in_reserved(newOop), "Bad pop"); 402 assert(newOop->is_oop(), "Expected an oop"); 403 assert(bm == NULL || bm->isMarked((HeapWord*)newOop), 404 "only grey objects on this stack"); 405 newOop->oop_iterate(cl); 406 if (yield_after && _cm->do_yield_check()) { 407 res = false; 408 break; 409 } 410 } 411 debug_only(_drain_in_progress = false); 412 return res; 413 } 414 415 void CMMarkStack::note_start_of_gc() { 416 assert(_saved_index == -1, 417 "note_start_of_gc()/end_of_gc() bracketed incorrectly"); 418 _saved_index = _index; 419 } 420 421 void CMMarkStack::note_end_of_gc() { 422 // This is intentionally a guarantee, instead of an assert. If we 423 // accidentally add something to the mark stack during GC, it 424 // will be a correctness issue so it's better if we crash. we'll 425 // only check this once per GC anyway, so it won't be a performance 426 // issue in any way. 427 guarantee(_saved_index == _index, 428 err_msg("saved index: %d index: %d", _saved_index, _index)); 429 _saved_index = -1; 430 } 431 432 void CMMarkStack::oops_do(OopClosure* f) { 433 assert(_saved_index == _index, 434 err_msg("saved index: %d index: %d", _saved_index, _index)); 435 for (int i = 0; i < _index; i += 1) { 436 f->do_oop(&_base[i]); 437 } 438 } 439 440 CMRootRegions::CMRootRegions() : 441 _young_list(NULL), _cm(NULL), _scan_in_progress(false), 442 _should_abort(false), _next_survivor(NULL) { } 443 444 void CMRootRegions::init(G1CollectedHeap* g1h, ConcurrentMark* cm) { 445 _young_list = g1h->young_list(); 446 _cm = cm; 447 } 448 449 void CMRootRegions::prepare_for_scan() { 450 assert(!scan_in_progress(), "pre-condition"); 451 452 // Currently, only survivors can be root regions. 453 assert(_next_survivor == NULL, "pre-condition"); 454 _next_survivor = _young_list->first_survivor_region(); 455 _scan_in_progress = (_next_survivor != NULL); 456 _should_abort = false; 457 } 458 459 HeapRegion* CMRootRegions::claim_next() { 460 if (_should_abort) { 461 // If someone has set the should_abort flag, we return NULL to 462 // force the caller to bail out of their loop. 463 return NULL; 464 } 465 466 // Currently, only survivors can be root regions. 467 HeapRegion* res = _next_survivor; 468 if (res != NULL) { 469 MutexLockerEx x(RootRegionScan_lock, Mutex::_no_safepoint_check_flag); 470 // Read it again in case it changed while we were waiting for the lock. 471 res = _next_survivor; 472 if (res != NULL) { 473 if (res == _young_list->last_survivor_region()) { 474 // We just claimed the last survivor so store NULL to indicate 475 // that we're done. 476 _next_survivor = NULL; 477 } else { 478 _next_survivor = res->get_next_young_region(); 479 } 480 } else { 481 // Someone else claimed the last survivor while we were trying 482 // to take the lock so nothing else to do. 483 } 484 } 485 assert(res == NULL || res->is_survivor(), "post-condition"); 486 487 return res; 488 } 489 490 void CMRootRegions::scan_finished() { 491 assert(scan_in_progress(), "pre-condition"); 492 493 // Currently, only survivors can be root regions. 494 if (!_should_abort) { 495 assert(_next_survivor == NULL, "we should have claimed all survivors"); 496 } 497 _next_survivor = NULL; 498 499 { 500 MutexLockerEx x(RootRegionScan_lock, Mutex::_no_safepoint_check_flag); 501 _scan_in_progress = false; 502 RootRegionScan_lock->notify_all(); 503 } 504 } 505 506 bool CMRootRegions::wait_until_scan_finished() { 507 if (!scan_in_progress()) return false; 508 509 { 510 MutexLockerEx x(RootRegionScan_lock, Mutex::_no_safepoint_check_flag); 511 while (scan_in_progress()) { 512 RootRegionScan_lock->wait(Mutex::_no_safepoint_check_flag); 513 } 514 } 515 return true; 516 } 517 518 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away 519 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list 520 #endif // _MSC_VER 521 522 uint ConcurrentMark::scale_parallel_threads(uint n_par_threads) { 523 return MAX2((n_par_threads + 2) / 4, 1U); 524 } 525 526 ConcurrentMark::ConcurrentMark(G1CollectedHeap* g1h, G1RegionToSpaceMapper* prev_bitmap_storage, G1RegionToSpaceMapper* next_bitmap_storage) : 527 _g1h(g1h), 528 _markBitMap1(), 529 _markBitMap2(), 530 _parallel_marking_threads(0), 531 _max_parallel_marking_threads(0), 532 _sleep_factor(0.0), 533 _marking_task_overhead(1.0), 534 _cleanup_sleep_factor(0.0), 535 _cleanup_task_overhead(1.0), 536 _cleanup_list("Cleanup List"), 537 _region_bm((BitMap::idx_t)(g1h->max_regions()), false /* in_resource_area*/), 538 _card_bm((g1h->reserved_region().byte_size() + CardTableModRefBS::card_size - 1) >> 539 CardTableModRefBS::card_shift, 540 false /* in_resource_area*/), 541 542 _prevMarkBitMap(&_markBitMap1), 543 _nextMarkBitMap(&_markBitMap2), 544 545 _markStack(this), 546 // _finger set in set_non_marking_state 547 548 _max_worker_id(MAX2((uint)ParallelGCThreads, 1U)), 549 // _active_tasks set in set_non_marking_state 550 // _tasks set inside the constructor 551 _task_queues(new CMTaskQueueSet((int) _max_worker_id)), 552 _terminator(ParallelTaskTerminator((int) _max_worker_id, _task_queues)), 553 554 _has_overflown(false), 555 _concurrent(false), 556 _has_aborted(false), 557 _aborted_gc_id(GCId::undefined()), 558 _restart_for_overflow(false), 559 _concurrent_marking_in_progress(false), 560 561 // _verbose_level set below 562 563 _init_times(), 564 _remark_times(), _remark_mark_times(), _remark_weak_ref_times(), 565 _cleanup_times(), 566 _total_counting_time(0.0), 567 _total_rs_scrub_time(0.0), 568 569 _parallel_workers(NULL), 570 571 _count_card_bitmaps(NULL), 572 _count_marked_bytes(NULL), 573 _completed_initialization(false) { 574 CMVerboseLevel verbose_level = (CMVerboseLevel) G1MarkingVerboseLevel; 575 if (verbose_level < no_verbose) { 576 verbose_level = no_verbose; 577 } 578 if (verbose_level > high_verbose) { 579 verbose_level = high_verbose; 580 } 581 _verbose_level = verbose_level; 582 583 if (verbose_low()) { 584 gclog_or_tty->print_cr("[global] init, heap start = "PTR_FORMAT", " 585 "heap end = " INTPTR_FORMAT, p2i(_heap_start), p2i(_heap_end)); 586 } 587 588 _markBitMap1.initialize(g1h->reserved_region(), prev_bitmap_storage); 589 _markBitMap2.initialize(g1h->reserved_region(), next_bitmap_storage); 590 591 // Create & start a ConcurrentMark thread. 592 _cmThread = new ConcurrentMarkThread(this); 593 assert(cmThread() != NULL, "CM Thread should have been created"); 594 assert(cmThread()->cm() != NULL, "CM Thread should refer to this cm"); 595 if (_cmThread->osthread() == NULL) { 596 vm_shutdown_during_initialization("Could not create ConcurrentMarkThread"); 597 } 598 599 assert(CGC_lock != NULL, "Where's the CGC_lock?"); 600 assert(_markBitMap1.covers(g1h->reserved_region()), "_markBitMap1 inconsistency"); 601 assert(_markBitMap2.covers(g1h->reserved_region()), "_markBitMap2 inconsistency"); 602 603 SATBMarkQueueSet& satb_qs = JavaThread::satb_mark_queue_set(); 604 satb_qs.set_buffer_size(G1SATBBufferSize); 605 606 _root_regions.init(_g1h, this); 607 608 if (ConcGCThreads > ParallelGCThreads) { 609 warning("Can't have more ConcGCThreads (" UINTX_FORMAT ") " 610 "than ParallelGCThreads (" UINTX_FORMAT ").", 611 ConcGCThreads, ParallelGCThreads); 612 return; 613 } 614 if (ParallelGCThreads == 0) { 615 // if we are not running with any parallel GC threads we will not 616 // spawn any marking threads either 617 _parallel_marking_threads = 0; 618 _max_parallel_marking_threads = 0; 619 _sleep_factor = 0.0; 620 _marking_task_overhead = 1.0; 621 } else { 622 if (!FLAG_IS_DEFAULT(ConcGCThreads) && ConcGCThreads > 0) { 623 // Note: ConcGCThreads has precedence over G1MarkingOverheadPercent 624 // if both are set 625 _sleep_factor = 0.0; 626 _marking_task_overhead = 1.0; 627 } else if (G1MarkingOverheadPercent > 0) { 628 // We will calculate the number of parallel marking threads based 629 // on a target overhead with respect to the soft real-time goal 630 double marking_overhead = (double) G1MarkingOverheadPercent / 100.0; 631 double overall_cm_overhead = 632 (double) MaxGCPauseMillis * marking_overhead / 633 (double) GCPauseIntervalMillis; 634 double cpu_ratio = 1.0 / (double) os::processor_count(); 635 double marking_thread_num = ceil(overall_cm_overhead / cpu_ratio); 636 double marking_task_overhead = 637 overall_cm_overhead / marking_thread_num * 638 (double) os::processor_count(); 639 double sleep_factor = 640 (1.0 - marking_task_overhead) / marking_task_overhead; 641 642 FLAG_SET_ERGO(uintx, ConcGCThreads, (uint) marking_thread_num); 643 _sleep_factor = sleep_factor; 644 _marking_task_overhead = marking_task_overhead; 645 } else { 646 // Calculate the number of parallel marking threads by scaling 647 // the number of parallel GC threads. 648 uint marking_thread_num = scale_parallel_threads((uint) ParallelGCThreads); 649 FLAG_SET_ERGO(uintx, ConcGCThreads, marking_thread_num); 650 _sleep_factor = 0.0; 651 _marking_task_overhead = 1.0; 652 } 653 654 assert(ConcGCThreads > 0, "Should have been set"); 655 _parallel_marking_threads = (uint) ConcGCThreads; 656 _max_parallel_marking_threads = _parallel_marking_threads; 657 658 if (parallel_marking_threads() > 1) { 659 _cleanup_task_overhead = 1.0; 660 } else { 661 _cleanup_task_overhead = marking_task_overhead(); 662 } 663 _cleanup_sleep_factor = 664 (1.0 - cleanup_task_overhead()) / cleanup_task_overhead(); 665 666 #if 0 667 gclog_or_tty->print_cr("Marking Threads %d", parallel_marking_threads()); 668 gclog_or_tty->print_cr("CM Marking Task Overhead %1.4lf", marking_task_overhead()); 669 gclog_or_tty->print_cr("CM Sleep Factor %1.4lf", sleep_factor()); 670 gclog_or_tty->print_cr("CL Marking Task Overhead %1.4lf", cleanup_task_overhead()); 671 gclog_or_tty->print_cr("CL Sleep Factor %1.4lf", cleanup_sleep_factor()); 672 #endif 673 674 guarantee(parallel_marking_threads() > 0, "peace of mind"); 675 _parallel_workers = new FlexibleWorkGang("G1 Parallel Marking Threads", 676 _max_parallel_marking_threads, false, true); 677 if (_parallel_workers == NULL) { 678 vm_exit_during_initialization("Failed necessary allocation."); 679 } else { 680 _parallel_workers->initialize_workers(); 681 } 682 } 683 684 if (FLAG_IS_DEFAULT(MarkStackSize)) { 685 uintx mark_stack_size = 686 MIN2(MarkStackSizeMax, 687 MAX2(MarkStackSize, (uintx) (parallel_marking_threads() * TASKQUEUE_SIZE))); 688 // Verify that the calculated value for MarkStackSize is in range. 689 // It would be nice to use the private utility routine from Arguments. 690 if (!(mark_stack_size >= 1 && mark_stack_size <= MarkStackSizeMax)) { 691 warning("Invalid value calculated for MarkStackSize (" UINTX_FORMAT "): " 692 "must be between " UINTX_FORMAT " and " UINTX_FORMAT, 693 mark_stack_size, (uintx) 1, MarkStackSizeMax); 694 return; 695 } 696 FLAG_SET_ERGO(uintx, MarkStackSize, mark_stack_size); 697 } else { 698 // Verify MarkStackSize is in range. 699 if (FLAG_IS_CMDLINE(MarkStackSize)) { 700 if (FLAG_IS_DEFAULT(MarkStackSizeMax)) { 701 if (!(MarkStackSize >= 1 && MarkStackSize <= MarkStackSizeMax)) { 702 warning("Invalid value specified for MarkStackSize (" UINTX_FORMAT "): " 703 "must be between " UINTX_FORMAT " and " UINTX_FORMAT, 704 MarkStackSize, (uintx) 1, MarkStackSizeMax); 705 return; 706 } 707 } else if (FLAG_IS_CMDLINE(MarkStackSizeMax)) { 708 if (!(MarkStackSize >= 1 && MarkStackSize <= MarkStackSizeMax)) { 709 warning("Invalid value specified for MarkStackSize (" UINTX_FORMAT ")" 710 " or for MarkStackSizeMax (" UINTX_FORMAT ")", 711 MarkStackSize, MarkStackSizeMax); 712 return; 713 } 714 } 715 } 716 } 717 718 if (!_markStack.allocate(MarkStackSize)) { 719 warning("Failed to allocate CM marking stack"); 720 return; 721 } 722 723 _tasks = NEW_C_HEAP_ARRAY(CMTask*, _max_worker_id, mtGC); 724 _accum_task_vtime = NEW_C_HEAP_ARRAY(double, _max_worker_id, mtGC); 725 726 _count_card_bitmaps = NEW_C_HEAP_ARRAY(BitMap, _max_worker_id, mtGC); 727 _count_marked_bytes = NEW_C_HEAP_ARRAY(size_t*, _max_worker_id, mtGC); 728 729 BitMap::idx_t card_bm_size = _card_bm.size(); 730 731 // so that the assertion in MarkingTaskQueue::task_queue doesn't fail 732 _active_tasks = _max_worker_id; 733 734 size_t max_regions = (size_t) _g1h->max_regions(); 735 for (uint i = 0; i < _max_worker_id; ++i) { 736 CMTaskQueue* task_queue = new CMTaskQueue(); 737 task_queue->initialize(); 738 _task_queues->register_queue(i, task_queue); 739 740 _count_card_bitmaps[i] = BitMap(card_bm_size, false); 741 _count_marked_bytes[i] = NEW_C_HEAP_ARRAY(size_t, max_regions, mtGC); 742 743 _tasks[i] = new CMTask(i, this, 744 _count_marked_bytes[i], 745 &_count_card_bitmaps[i], 746 task_queue, _task_queues); 747 748 _accum_task_vtime[i] = 0.0; 749 } 750 751 // Calculate the card number for the bottom of the heap. Used 752 // in biasing indexes into the accounting card bitmaps. 753 _heap_bottom_card_num = 754 intptr_t(uintptr_t(_g1h->reserved_region().start()) >> 755 CardTableModRefBS::card_shift); 756 757 // Clear all the liveness counting data 758 clear_all_count_data(); 759 760 // so that the call below can read a sensible value 761 _heap_start = g1h->reserved_region().start(); 762 set_non_marking_state(); 763 _completed_initialization = true; 764 } 765 766 void ConcurrentMark::reset() { 767 // Starting values for these two. This should be called in a STW 768 // phase. 769 MemRegion reserved = _g1h->g1_reserved(); 770 _heap_start = reserved.start(); 771 _heap_end = reserved.end(); 772 773 // Separated the asserts so that we know which one fires. 774 assert(_heap_start != NULL, "heap bounds should look ok"); 775 assert(_heap_end != NULL, "heap bounds should look ok"); 776 assert(_heap_start < _heap_end, "heap bounds should look ok"); 777 778 // Reset all the marking data structures and any necessary flags 779 reset_marking_state(); 780 781 if (verbose_low()) { 782 gclog_or_tty->print_cr("[global] resetting"); 783 } 784 785 // We do reset all of them, since different phases will use 786 // different number of active threads. So, it's easiest to have all 787 // of them ready. 788 for (uint i = 0; i < _max_worker_id; ++i) { 789 _tasks[i]->reset(_nextMarkBitMap); 790 } 791 792 // we need this to make sure that the flag is on during the evac 793 // pause with initial mark piggy-backed 794 set_concurrent_marking_in_progress(); 795 } 796 797 798 void ConcurrentMark::reset_marking_state(bool clear_overflow) { 799 _markStack.set_should_expand(); 800 _markStack.setEmpty(); // Also clears the _markStack overflow flag 801 if (clear_overflow) { 802 clear_has_overflown(); 803 } else { 804 assert(has_overflown(), "pre-condition"); 805 } 806 _finger = _heap_start; 807 808 for (uint i = 0; i < _max_worker_id; ++i) { 809 CMTaskQueue* queue = _task_queues->queue(i); 810 queue->set_empty(); 811 } 812 } 813 814 void ConcurrentMark::set_concurrency(uint active_tasks) { 815 assert(active_tasks <= _max_worker_id, "we should not have more"); 816 817 _active_tasks = active_tasks; 818 // Need to update the three data structures below according to the 819 // number of active threads for this phase. 820 _terminator = ParallelTaskTerminator((int) active_tasks, _task_queues); 821 _first_overflow_barrier_sync.set_n_workers((int) active_tasks); 822 _second_overflow_barrier_sync.set_n_workers((int) active_tasks); 823 } 824 825 void ConcurrentMark::set_concurrency_and_phase(uint active_tasks, bool concurrent) { 826 set_concurrency(active_tasks); 827 828 _concurrent = concurrent; 829 // We propagate this to all tasks, not just the active ones. 830 for (uint i = 0; i < _max_worker_id; ++i) 831 _tasks[i]->set_concurrent(concurrent); 832 833 if (concurrent) { 834 set_concurrent_marking_in_progress(); 835 } else { 836 // We currently assume that the concurrent flag has been set to 837 // false before we start remark. At this point we should also be 838 // in a STW phase. 839 assert(!concurrent_marking_in_progress(), "invariant"); 840 assert(out_of_regions(), 841 err_msg("only way to get here: _finger: "PTR_FORMAT", _heap_end: "PTR_FORMAT, 842 p2i(_finger), p2i(_heap_end))); 843 } 844 } 845 846 void ConcurrentMark::set_non_marking_state() { 847 // We set the global marking state to some default values when we're 848 // not doing marking. 849 reset_marking_state(); 850 _active_tasks = 0; 851 clear_concurrent_marking_in_progress(); 852 } 853 854 ConcurrentMark::~ConcurrentMark() { 855 // The ConcurrentMark instance is never freed. 856 ShouldNotReachHere(); 857 } 858 859 void ConcurrentMark::clearNextBitmap() { 860 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 861 862 // Make sure that the concurrent mark thread looks to still be in 863 // the current cycle. 864 guarantee(cmThread()->during_cycle(), "invariant"); 865 866 // We are finishing up the current cycle by clearing the next 867 // marking bitmap and getting it ready for the next cycle. During 868 // this time no other cycle can start. So, let's make sure that this 869 // is the case. 870 guarantee(!g1h->mark_in_progress(), "invariant"); 871 872 ClearBitmapHRClosure cl(this, _nextMarkBitMap, true /* may_yield */); 873 g1h->heap_region_iterate(&cl); 874 875 // Clear the liveness counting data. If the marking has been aborted, the abort() 876 // call already did that. 877 if (cl.complete()) { 878 clear_all_count_data(); 879 } 880 881 // Repeat the asserts from above. 882 guarantee(cmThread()->during_cycle(), "invariant"); 883 guarantee(!g1h->mark_in_progress(), "invariant"); 884 } 885 886 class CheckBitmapClearHRClosure : public HeapRegionClosure { 887 CMBitMap* _bitmap; 888 bool _error; 889 public: 890 CheckBitmapClearHRClosure(CMBitMap* bitmap) : _bitmap(bitmap) { 891 } 892 893 virtual bool doHeapRegion(HeapRegion* r) { 894 // This closure can be called concurrently to the mutator, so we must make sure 895 // that the result of the getNextMarkedWordAddress() call is compared to the 896 // value passed to it as limit to detect any found bits. 897 // We can use the region's orig_end() for the limit and the comparison value 898 // as it always contains the "real" end of the region that never changes and 899 // has no side effects. 900 // Due to the latter, there can also be no problem with the compiler generating 901 // reloads of the orig_end() call. 902 HeapWord* end = r->orig_end(); 903 return _bitmap->getNextMarkedWordAddress(r->bottom(), end) != end; 904 } 905 }; 906 907 bool ConcurrentMark::nextMarkBitmapIsClear() { 908 CheckBitmapClearHRClosure cl(_nextMarkBitMap); 909 _g1h->heap_region_iterate(&cl); 910 return cl.complete(); 911 } 912 913 class NoteStartOfMarkHRClosure: public HeapRegionClosure { 914 public: 915 bool doHeapRegion(HeapRegion* r) { 916 if (!r->continuesHumongous()) { 917 r->note_start_of_marking(); 918 } 919 return false; 920 } 921 }; 922 923 void ConcurrentMark::checkpointRootsInitialPre() { 924 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 925 G1CollectorPolicy* g1p = g1h->g1_policy(); 926 927 _has_aborted = false; 928 929 #ifndef PRODUCT 930 if (G1PrintReachableAtInitialMark) { 931 print_reachable("at-cycle-start", 932 VerifyOption_G1UsePrevMarking, true /* all */); 933 } 934 #endif 935 936 // Initialise marking structures. This has to be done in a STW phase. 937 reset(); 938 939 // For each region note start of marking. 940 NoteStartOfMarkHRClosure startcl; 941 g1h->heap_region_iterate(&startcl); 942 } 943 944 945 void ConcurrentMark::checkpointRootsInitialPost() { 946 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 947 948 // If we force an overflow during remark, the remark operation will 949 // actually abort and we'll restart concurrent marking. If we always 950 // force an oveflow during remark we'll never actually complete the 951 // marking phase. So, we initilize this here, at the start of the 952 // cycle, so that at the remaining overflow number will decrease at 953 // every remark and we'll eventually not need to cause one. 954 force_overflow_stw()->init(); 955 956 // Start Concurrent Marking weak-reference discovery. 957 ReferenceProcessor* rp = g1h->ref_processor_cm(); 958 // enable ("weak") refs discovery 959 rp->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/); 960 rp->setup_policy(false); // snapshot the soft ref policy to be used in this cycle 961 962 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set(); 963 // This is the start of the marking cycle, we're expected all 964 // threads to have SATB queues with active set to false. 965 satb_mq_set.set_active_all_threads(true, /* new active value */ 966 false /* expected_active */); 967 968 _root_regions.prepare_for_scan(); 969 970 // update_g1_committed() will be called at the end of an evac pause 971 // when marking is on. So, it's also called at the end of the 972 // initial-mark pause to update the heap end, if the heap expands 973 // during it. No need to call it here. 974 } 975 976 /* 977 * Notice that in the next two methods, we actually leave the STS 978 * during the barrier sync and join it immediately afterwards. If we 979 * do not do this, the following deadlock can occur: one thread could 980 * be in the barrier sync code, waiting for the other thread to also 981 * sync up, whereas another one could be trying to yield, while also 982 * waiting for the other threads to sync up too. 983 * 984 * Note, however, that this code is also used during remark and in 985 * this case we should not attempt to leave / enter the STS, otherwise 986 * we'll either hit an asseert (debug / fastdebug) or deadlock 987 * (product). So we should only leave / enter the STS if we are 988 * operating concurrently. 989 * 990 * Because the thread that does the sync barrier has left the STS, it 991 * is possible to be suspended for a Full GC or an evacuation pause 992 * could occur. This is actually safe, since the entering the sync 993 * barrier is one of the last things do_marking_step() does, and it 994 * doesn't manipulate any data structures afterwards. 995 */ 996 997 void ConcurrentMark::enter_first_sync_barrier(uint worker_id) { 998 if (verbose_low()) { 999 gclog_or_tty->print_cr("[%u] entering first barrier", worker_id); 1000 } 1001 1002 if (concurrent()) { 1003 SuspendibleThreadSet::leave(); 1004 } 1005 1006 bool barrier_aborted = !_first_overflow_barrier_sync.enter(); 1007 1008 if (concurrent()) { 1009 SuspendibleThreadSet::join(); 1010 } 1011 // at this point everyone should have synced up and not be doing any 1012 // more work 1013 1014 if (verbose_low()) { 1015 if (barrier_aborted) { 1016 gclog_or_tty->print_cr("[%u] aborted first barrier", worker_id); 1017 } else { 1018 gclog_or_tty->print_cr("[%u] leaving first barrier", worker_id); 1019 } 1020 } 1021 1022 if (barrier_aborted) { 1023 // If the barrier aborted we ignore the overflow condition and 1024 // just abort the whole marking phase as quickly as possible. 1025 return; 1026 } 1027 1028 // If we're executing the concurrent phase of marking, reset the marking 1029 // state; otherwise the marking state is reset after reference processing, 1030 // during the remark pause. 1031 // If we reset here as a result of an overflow during the remark we will 1032 // see assertion failures from any subsequent set_concurrency_and_phase() 1033 // calls. 1034 if (concurrent()) { 1035 // let the task associated with with worker 0 do this 1036 if (worker_id == 0) { 1037 // task 0 is responsible for clearing the global data structures 1038 // We should be here because of an overflow. During STW we should 1039 // not clear the overflow flag since we rely on it being true when 1040 // we exit this method to abort the pause and restart concurent 1041 // marking. 1042 reset_marking_state(true /* clear_overflow */); 1043 force_overflow()->update(); 1044 1045 if (G1Log::fine()) { 1046 gclog_or_tty->gclog_stamp(concurrent_gc_id()); 1047 gclog_or_tty->print_cr("[GC concurrent-mark-reset-for-overflow]"); 1048 } 1049 } 1050 } 1051 1052 // after this, each task should reset its own data structures then 1053 // then go into the second barrier 1054 } 1055 1056 void ConcurrentMark::enter_second_sync_barrier(uint worker_id) { 1057 if (verbose_low()) { 1058 gclog_or_tty->print_cr("[%u] entering second barrier", worker_id); 1059 } 1060 1061 if (concurrent()) { 1062 SuspendibleThreadSet::leave(); 1063 } 1064 1065 bool barrier_aborted = !_second_overflow_barrier_sync.enter(); 1066 1067 if (concurrent()) { 1068 SuspendibleThreadSet::join(); 1069 } 1070 // at this point everything should be re-initialized and ready to go 1071 1072 if (verbose_low()) { 1073 if (barrier_aborted) { 1074 gclog_or_tty->print_cr("[%u] aborted second barrier", worker_id); 1075 } else { 1076 gclog_or_tty->print_cr("[%u] leaving second barrier", worker_id); 1077 } 1078 } 1079 } 1080 1081 #ifndef PRODUCT 1082 void ForceOverflowSettings::init() { 1083 _num_remaining = G1ConcMarkForceOverflow; 1084 _force = false; 1085 update(); 1086 } 1087 1088 void ForceOverflowSettings::update() { 1089 if (_num_remaining > 0) { 1090 _num_remaining -= 1; 1091 _force = true; 1092 } else { 1093 _force = false; 1094 } 1095 } 1096 1097 bool ForceOverflowSettings::should_force() { 1098 if (_force) { 1099 _force = false; 1100 return true; 1101 } else { 1102 return false; 1103 } 1104 } 1105 #endif // !PRODUCT 1106 1107 class CMConcurrentMarkingTask: public AbstractGangTask { 1108 private: 1109 ConcurrentMark* _cm; 1110 ConcurrentMarkThread* _cmt; 1111 1112 public: 1113 void work(uint worker_id) { 1114 assert(Thread::current()->is_ConcurrentGC_thread(), 1115 "this should only be done by a conc GC thread"); 1116 ResourceMark rm; 1117 1118 double start_vtime = os::elapsedVTime(); 1119 1120 SuspendibleThreadSet::join(); 1121 1122 assert(worker_id < _cm->active_tasks(), "invariant"); 1123 CMTask* the_task = _cm->task(worker_id); 1124 the_task->record_start_time(); 1125 if (!_cm->has_aborted()) { 1126 do { 1127 double start_vtime_sec = os::elapsedVTime(); 1128 double mark_step_duration_ms = G1ConcMarkStepDurationMillis; 1129 1130 the_task->do_marking_step(mark_step_duration_ms, 1131 true /* do_termination */, 1132 false /* is_serial*/); 1133 1134 double end_vtime_sec = os::elapsedVTime(); 1135 double elapsed_vtime_sec = end_vtime_sec - start_vtime_sec; 1136 _cm->clear_has_overflown(); 1137 1138 _cm->do_yield_check(worker_id); 1139 1140 jlong sleep_time_ms; 1141 if (!_cm->has_aborted() && the_task->has_aborted()) { 1142 sleep_time_ms = 1143 (jlong) (elapsed_vtime_sec * _cm->sleep_factor() * 1000.0); 1144 SuspendibleThreadSet::leave(); 1145 os::sleep(Thread::current(), sleep_time_ms, false); 1146 SuspendibleThreadSet::join(); 1147 } 1148 } while (!_cm->has_aborted() && the_task->has_aborted()); 1149 } 1150 the_task->record_end_time(); 1151 guarantee(!the_task->has_aborted() || _cm->has_aborted(), "invariant"); 1152 1153 SuspendibleThreadSet::leave(); 1154 1155 double end_vtime = os::elapsedVTime(); 1156 _cm->update_accum_task_vtime(worker_id, end_vtime - start_vtime); 1157 } 1158 1159 CMConcurrentMarkingTask(ConcurrentMark* cm, 1160 ConcurrentMarkThread* cmt) : 1161 AbstractGangTask("Concurrent Mark"), _cm(cm), _cmt(cmt) { } 1162 1163 ~CMConcurrentMarkingTask() { } 1164 }; 1165 1166 // Calculates the number of active workers for a concurrent 1167 // phase. 1168 uint ConcurrentMark::calc_parallel_marking_threads() { 1169 if (G1CollectedHeap::use_parallel_gc_threads()) { 1170 uint n_conc_workers = 0; 1171 if (!UseDynamicNumberOfGCThreads || 1172 (!FLAG_IS_DEFAULT(ConcGCThreads) && 1173 !ForceDynamicNumberOfGCThreads)) { 1174 n_conc_workers = max_parallel_marking_threads(); 1175 } else { 1176 n_conc_workers = 1177 AdaptiveSizePolicy::calc_default_active_workers( 1178 max_parallel_marking_threads(), 1179 1, /* Minimum workers */ 1180 parallel_marking_threads(), 1181 Threads::number_of_non_daemon_threads()); 1182 // Don't scale down "n_conc_workers" by scale_parallel_threads() because 1183 // that scaling has already gone into "_max_parallel_marking_threads". 1184 } 1185 assert(n_conc_workers > 0, "Always need at least 1"); 1186 return n_conc_workers; 1187 } 1188 // If we are not running with any parallel GC threads we will not 1189 // have spawned any marking threads either. Hence the number of 1190 // concurrent workers should be 0. 1191 return 0; 1192 } 1193 1194 void ConcurrentMark::scanRootRegion(HeapRegion* hr, uint worker_id) { 1195 // Currently, only survivors can be root regions. 1196 assert(hr->next_top_at_mark_start() == hr->bottom(), "invariant"); 1197 G1RootRegionScanClosure cl(_g1h, this, worker_id); 1198 1199 const uintx interval = PrefetchScanIntervalInBytes; 1200 HeapWord* curr = hr->bottom(); 1201 const HeapWord* end = hr->top(); 1202 while (curr < end) { 1203 Prefetch::read(curr, interval); 1204 oop obj = oop(curr); 1205 int size = obj->oop_iterate(&cl); 1206 assert(size == obj->size(), "sanity"); 1207 curr += size; 1208 } 1209 } 1210 1211 class CMRootRegionScanTask : public AbstractGangTask { 1212 private: 1213 ConcurrentMark* _cm; 1214 1215 public: 1216 CMRootRegionScanTask(ConcurrentMark* cm) : 1217 AbstractGangTask("Root Region Scan"), _cm(cm) { } 1218 1219 void work(uint worker_id) { 1220 assert(Thread::current()->is_ConcurrentGC_thread(), 1221 "this should only be done by a conc GC thread"); 1222 1223 CMRootRegions* root_regions = _cm->root_regions(); 1224 HeapRegion* hr = root_regions->claim_next(); 1225 while (hr != NULL) { 1226 _cm->scanRootRegion(hr, worker_id); 1227 hr = root_regions->claim_next(); 1228 } 1229 } 1230 }; 1231 1232 void ConcurrentMark::scanRootRegions() { 1233 // Start of concurrent marking. 1234 ClassLoaderDataGraph::clear_claimed_marks(); 1235 1236 // scan_in_progress() will have been set to true only if there was 1237 // at least one root region to scan. So, if it's false, we 1238 // should not attempt to do any further work. 1239 if (root_regions()->scan_in_progress()) { 1240 _parallel_marking_threads = calc_parallel_marking_threads(); 1241 assert(parallel_marking_threads() <= max_parallel_marking_threads(), 1242 "Maximum number of marking threads exceeded"); 1243 uint active_workers = MAX2(1U, parallel_marking_threads()); 1244 1245 CMRootRegionScanTask task(this); 1246 if (use_parallel_marking_threads()) { 1247 _parallel_workers->set_active_workers((int) active_workers); 1248 _parallel_workers->run_task(&task); 1249 } else { 1250 task.work(0); 1251 } 1252 1253 // It's possible that has_aborted() is true here without actually 1254 // aborting the survivor scan earlier. This is OK as it's 1255 // mainly used for sanity checking. 1256 root_regions()->scan_finished(); 1257 } 1258 } 1259 1260 void ConcurrentMark::markFromRoots() { 1261 // we might be tempted to assert that: 1262 // assert(asynch == !SafepointSynchronize::is_at_safepoint(), 1263 // "inconsistent argument?"); 1264 // However that wouldn't be right, because it's possible that 1265 // a safepoint is indeed in progress as a younger generation 1266 // stop-the-world GC happens even as we mark in this generation. 1267 1268 _restart_for_overflow = false; 1269 force_overflow_conc()->init(); 1270 1271 // _g1h has _n_par_threads 1272 _parallel_marking_threads = calc_parallel_marking_threads(); 1273 assert(parallel_marking_threads() <= max_parallel_marking_threads(), 1274 "Maximum number of marking threads exceeded"); 1275 1276 uint active_workers = MAX2(1U, parallel_marking_threads()); 1277 1278 // Parallel task terminator is set in "set_concurrency_and_phase()" 1279 set_concurrency_and_phase(active_workers, true /* concurrent */); 1280 1281 CMConcurrentMarkingTask markingTask(this, cmThread()); 1282 if (use_parallel_marking_threads()) { 1283 _parallel_workers->set_active_workers((int)active_workers); 1284 // Don't set _n_par_threads because it affects MT in process_roots() 1285 // and the decisions on that MT processing is made elsewhere. 1286 assert(_parallel_workers->active_workers() > 0, "Should have been set"); 1287 _parallel_workers->run_task(&markingTask); 1288 } else { 1289 markingTask.work(0); 1290 } 1291 print_stats(); 1292 } 1293 1294 void ConcurrentMark::checkpointRootsFinal(bool clear_all_soft_refs) { 1295 // world is stopped at this checkpoint 1296 assert(SafepointSynchronize::is_at_safepoint(), 1297 "world should be stopped"); 1298 1299 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 1300 1301 // If a full collection has happened, we shouldn't do this. 1302 if (has_aborted()) { 1303 g1h->set_marking_complete(); // So bitmap clearing isn't confused 1304 return; 1305 } 1306 1307 SvcGCMarker sgcm(SvcGCMarker::OTHER); 1308 1309 if (VerifyDuringGC) { 1310 HandleMark hm; // handle scope 1311 Universe::heap()->prepare_for_verify(); 1312 Universe::verify(VerifyOption_G1UsePrevMarking, 1313 " VerifyDuringGC:(before)"); 1314 } 1315 g1h->check_bitmaps("Remark Start"); 1316 1317 G1CollectorPolicy* g1p = g1h->g1_policy(); 1318 g1p->record_concurrent_mark_remark_start(); 1319 1320 double start = os::elapsedTime(); 1321 1322 checkpointRootsFinalWork(); 1323 1324 double mark_work_end = os::elapsedTime(); 1325 1326 weakRefsWork(clear_all_soft_refs); 1327 1328 if (has_overflown()) { 1329 // Oops. We overflowed. Restart concurrent marking. 1330 _restart_for_overflow = true; 1331 if (G1TraceMarkStackOverflow) { 1332 gclog_or_tty->print_cr("\nRemark led to restart for overflow."); 1333 } 1334 1335 // Verify the heap w.r.t. the previous marking bitmap. 1336 if (VerifyDuringGC) { 1337 HandleMark hm; // handle scope 1338 Universe::heap()->prepare_for_verify(); 1339 Universe::verify(VerifyOption_G1UsePrevMarking, 1340 " VerifyDuringGC:(overflow)"); 1341 } 1342 1343 // Clear the marking state because we will be restarting 1344 // marking due to overflowing the global mark stack. 1345 reset_marking_state(); 1346 } else { 1347 // Aggregate the per-task counting data that we have accumulated 1348 // while marking. 1349 aggregate_count_data(); 1350 1351 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set(); 1352 // We're done with marking. 1353 // This is the end of the marking cycle, we're expected all 1354 // threads to have SATB queues with active set to true. 1355 satb_mq_set.set_active_all_threads(false, /* new active value */ 1356 true /* expected_active */); 1357 1358 if (VerifyDuringGC) { 1359 HandleMark hm; // handle scope 1360 Universe::heap()->prepare_for_verify(); 1361 Universe::verify(VerifyOption_G1UseNextMarking, 1362 " VerifyDuringGC:(after)"); 1363 } 1364 g1h->check_bitmaps("Remark End"); 1365 assert(!restart_for_overflow(), "sanity"); 1366 // Completely reset the marking state since marking completed 1367 set_non_marking_state(); 1368 } 1369 1370 // Expand the marking stack, if we have to and if we can. 1371 if (_markStack.should_expand()) { 1372 _markStack.expand(); 1373 } 1374 1375 // Statistics 1376 double now = os::elapsedTime(); 1377 _remark_mark_times.add((mark_work_end - start) * 1000.0); 1378 _remark_weak_ref_times.add((now - mark_work_end) * 1000.0); 1379 _remark_times.add((now - start) * 1000.0); 1380 1381 g1p->record_concurrent_mark_remark_end(); 1382 1383 G1CMIsAliveClosure is_alive(g1h); 1384 g1h->gc_tracer_cm()->report_object_count_after_gc(&is_alive); 1385 } 1386 1387 // Base class of the closures that finalize and verify the 1388 // liveness counting data. 1389 class CMCountDataClosureBase: public HeapRegionClosure { 1390 protected: 1391 G1CollectedHeap* _g1h; 1392 ConcurrentMark* _cm; 1393 CardTableModRefBS* _ct_bs; 1394 1395 BitMap* _region_bm; 1396 BitMap* _card_bm; 1397 1398 // Takes a region that's not empty (i.e., it has at least one 1399 // live object in it and sets its corresponding bit on the region 1400 // bitmap to 1. If the region is "starts humongous" it will also set 1401 // to 1 the bits on the region bitmap that correspond to its 1402 // associated "continues humongous" regions. 1403 void set_bit_for_region(HeapRegion* hr) { 1404 assert(!hr->continuesHumongous(), "should have filtered those out"); 1405 1406 BitMap::idx_t index = (BitMap::idx_t) hr->hrm_index(); 1407 if (!hr->startsHumongous()) { 1408 // Normal (non-humongous) case: just set the bit. 1409 _region_bm->par_at_put(index, true); 1410 } else { 1411 // Starts humongous case: calculate how many regions are part of 1412 // this humongous region and then set the bit range. 1413 BitMap::idx_t end_index = (BitMap::idx_t) hr->last_hc_index(); 1414 _region_bm->par_at_put_range(index, end_index, true); 1415 } 1416 } 1417 1418 public: 1419 CMCountDataClosureBase(G1CollectedHeap* g1h, 1420 BitMap* region_bm, BitMap* card_bm): 1421 _g1h(g1h), _cm(g1h->concurrent_mark()), 1422 _ct_bs((CardTableModRefBS*) (g1h->barrier_set())), 1423 _region_bm(region_bm), _card_bm(card_bm) { } 1424 }; 1425 1426 // Closure that calculates the # live objects per region. Used 1427 // for verification purposes during the cleanup pause. 1428 class CalcLiveObjectsClosure: public CMCountDataClosureBase { 1429 CMBitMapRO* _bm; 1430 size_t _region_marked_bytes; 1431 1432 public: 1433 CalcLiveObjectsClosure(CMBitMapRO *bm, G1CollectedHeap* g1h, 1434 BitMap* region_bm, BitMap* card_bm) : 1435 CMCountDataClosureBase(g1h, region_bm, card_bm), 1436 _bm(bm), _region_marked_bytes(0) { } 1437 1438 bool doHeapRegion(HeapRegion* hr) { 1439 1440 if (hr->continuesHumongous()) { 1441 // We will ignore these here and process them when their 1442 // associated "starts humongous" region is processed (see 1443 // set_bit_for_heap_region()). Note that we cannot rely on their 1444 // associated "starts humongous" region to have their bit set to 1445 // 1 since, due to the region chunking in the parallel region 1446 // iteration, a "continues humongous" region might be visited 1447 // before its associated "starts humongous". 1448 return false; 1449 } 1450 1451 HeapWord* ntams = hr->next_top_at_mark_start(); 1452 HeapWord* start = hr->bottom(); 1453 1454 assert(start <= hr->end() && start <= ntams && ntams <= hr->end(), 1455 err_msg("Preconditions not met - " 1456 "start: "PTR_FORMAT", ntams: "PTR_FORMAT", end: "PTR_FORMAT, 1457 p2i(start), p2i(ntams), p2i(hr->end()))); 1458 1459 // Find the first marked object at or after "start". 1460 start = _bm->getNextMarkedWordAddress(start, ntams); 1461 1462 size_t marked_bytes = 0; 1463 1464 while (start < ntams) { 1465 oop obj = oop(start); 1466 int obj_sz = obj->size(); 1467 HeapWord* obj_end = start + obj_sz; 1468 1469 BitMap::idx_t start_idx = _cm->card_bitmap_index_for(start); 1470 BitMap::idx_t end_idx = _cm->card_bitmap_index_for(obj_end); 1471 1472 // Note: if we're looking at the last region in heap - obj_end 1473 // could be actually just beyond the end of the heap; end_idx 1474 // will then correspond to a (non-existent) card that is also 1475 // just beyond the heap. 1476 if (_g1h->is_in_g1_reserved(obj_end) && !_ct_bs->is_card_aligned(obj_end)) { 1477 // end of object is not card aligned - increment to cover 1478 // all the cards spanned by the object 1479 end_idx += 1; 1480 } 1481 1482 // Set the bits in the card BM for the cards spanned by this object. 1483 _cm->set_card_bitmap_range(_card_bm, start_idx, end_idx, true /* is_par */); 1484 1485 // Add the size of this object to the number of marked bytes. 1486 marked_bytes += (size_t)obj_sz * HeapWordSize; 1487 1488 // Find the next marked object after this one. 1489 start = _bm->getNextMarkedWordAddress(obj_end, ntams); 1490 } 1491 1492 // Mark the allocated-since-marking portion... 1493 HeapWord* top = hr->top(); 1494 if (ntams < top) { 1495 BitMap::idx_t start_idx = _cm->card_bitmap_index_for(ntams); 1496 BitMap::idx_t end_idx = _cm->card_bitmap_index_for(top); 1497 1498 // Note: if we're looking at the last region in heap - top 1499 // could be actually just beyond the end of the heap; end_idx 1500 // will then correspond to a (non-existent) card that is also 1501 // just beyond the heap. 1502 if (_g1h->is_in_g1_reserved(top) && !_ct_bs->is_card_aligned(top)) { 1503 // end of object is not card aligned - increment to cover 1504 // all the cards spanned by the object 1505 end_idx += 1; 1506 } 1507 _cm->set_card_bitmap_range(_card_bm, start_idx, end_idx, true /* is_par */); 1508 1509 // This definitely means the region has live objects. 1510 set_bit_for_region(hr); 1511 } 1512 1513 // Update the live region bitmap. 1514 if (marked_bytes > 0) { 1515 set_bit_for_region(hr); 1516 } 1517 1518 // Set the marked bytes for the current region so that 1519 // it can be queried by a calling verificiation routine 1520 _region_marked_bytes = marked_bytes; 1521 1522 return false; 1523 } 1524 1525 size_t region_marked_bytes() const { return _region_marked_bytes; } 1526 }; 1527 1528 // Heap region closure used for verifying the counting data 1529 // that was accumulated concurrently and aggregated during 1530 // the remark pause. This closure is applied to the heap 1531 // regions during the STW cleanup pause. 1532 1533 class VerifyLiveObjectDataHRClosure: public HeapRegionClosure { 1534 G1CollectedHeap* _g1h; 1535 ConcurrentMark* _cm; 1536 CalcLiveObjectsClosure _calc_cl; 1537 BitMap* _region_bm; // Region BM to be verified 1538 BitMap* _card_bm; // Card BM to be verified 1539 bool _verbose; // verbose output? 1540 1541 BitMap* _exp_region_bm; // Expected Region BM values 1542 BitMap* _exp_card_bm; // Expected card BM values 1543 1544 int _failures; 1545 1546 public: 1547 VerifyLiveObjectDataHRClosure(G1CollectedHeap* g1h, 1548 BitMap* region_bm, 1549 BitMap* card_bm, 1550 BitMap* exp_region_bm, 1551 BitMap* exp_card_bm, 1552 bool verbose) : 1553 _g1h(g1h), _cm(g1h->concurrent_mark()), 1554 _calc_cl(_cm->nextMarkBitMap(), g1h, exp_region_bm, exp_card_bm), 1555 _region_bm(region_bm), _card_bm(card_bm), _verbose(verbose), 1556 _exp_region_bm(exp_region_bm), _exp_card_bm(exp_card_bm), 1557 _failures(0) { } 1558 1559 int failures() const { return _failures; } 1560 1561 bool doHeapRegion(HeapRegion* hr) { 1562 if (hr->continuesHumongous()) { 1563 // We will ignore these here and process them when their 1564 // associated "starts humongous" region is processed (see 1565 // set_bit_for_heap_region()). Note that we cannot rely on their 1566 // associated "starts humongous" region to have their bit set to 1567 // 1 since, due to the region chunking in the parallel region 1568 // iteration, a "continues humongous" region might be visited 1569 // before its associated "starts humongous". 1570 return false; 1571 } 1572 1573 int failures = 0; 1574 1575 // Call the CalcLiveObjectsClosure to walk the marking bitmap for 1576 // this region and set the corresponding bits in the expected region 1577 // and card bitmaps. 1578 bool res = _calc_cl.doHeapRegion(hr); 1579 assert(res == false, "should be continuing"); 1580 1581 MutexLockerEx x((_verbose ? ParGCRareEvent_lock : NULL), 1582 Mutex::_no_safepoint_check_flag); 1583 1584 // Verify the marked bytes for this region. 1585 size_t exp_marked_bytes = _calc_cl.region_marked_bytes(); 1586 size_t act_marked_bytes = hr->next_marked_bytes(); 1587 1588 // We're not OK if expected marked bytes > actual marked bytes. It means 1589 // we have missed accounting some objects during the actual marking. 1590 if (exp_marked_bytes > act_marked_bytes) { 1591 if (_verbose) { 1592 gclog_or_tty->print_cr("Region %u: marked bytes mismatch: " 1593 "expected: " SIZE_FORMAT ", actual: " SIZE_FORMAT, 1594 hr->hrm_index(), exp_marked_bytes, act_marked_bytes); 1595 } 1596 failures += 1; 1597 } 1598 1599 // Verify the bit, for this region, in the actual and expected 1600 // (which was just calculated) region bit maps. 1601 // We're not OK if the bit in the calculated expected region 1602 // bitmap is set and the bit in the actual region bitmap is not. 1603 BitMap::idx_t index = (BitMap::idx_t) hr->hrm_index(); 1604 1605 bool expected = _exp_region_bm->at(index); 1606 bool actual = _region_bm->at(index); 1607 if (expected && !actual) { 1608 if (_verbose) { 1609 gclog_or_tty->print_cr("Region %u: region bitmap mismatch: " 1610 "expected: %s, actual: %s", 1611 hr->hrm_index(), 1612 BOOL_TO_STR(expected), BOOL_TO_STR(actual)); 1613 } 1614 failures += 1; 1615 } 1616 1617 // Verify that the card bit maps for the cards spanned by the current 1618 // region match. We have an error if we have a set bit in the expected 1619 // bit map and the corresponding bit in the actual bitmap is not set. 1620 1621 BitMap::idx_t start_idx = _cm->card_bitmap_index_for(hr->bottom()); 1622 BitMap::idx_t end_idx = _cm->card_bitmap_index_for(hr->top()); 1623 1624 for (BitMap::idx_t i = start_idx; i < end_idx; i+=1) { 1625 expected = _exp_card_bm->at(i); 1626 actual = _card_bm->at(i); 1627 1628 if (expected && !actual) { 1629 if (_verbose) { 1630 gclog_or_tty->print_cr("Region %u: card bitmap mismatch at " SIZE_FORMAT ": " 1631 "expected: %s, actual: %s", 1632 hr->hrm_index(), i, 1633 BOOL_TO_STR(expected), BOOL_TO_STR(actual)); 1634 } 1635 failures += 1; 1636 } 1637 } 1638 1639 if (failures > 0 && _verbose) { 1640 gclog_or_tty->print_cr("Region " HR_FORMAT ", ntams: " PTR_FORMAT ", " 1641 "marked_bytes: calc/actual " SIZE_FORMAT "/" SIZE_FORMAT, 1642 HR_FORMAT_PARAMS(hr), p2i(hr->next_top_at_mark_start()), 1643 _calc_cl.region_marked_bytes(), hr->next_marked_bytes()); 1644 } 1645 1646 _failures += failures; 1647 1648 // We could stop iteration over the heap when we 1649 // find the first violating region by returning true. 1650 return false; 1651 } 1652 }; 1653 1654 class G1ParVerifyFinalCountTask: public AbstractGangTask { 1655 protected: 1656 G1CollectedHeap* _g1h; 1657 ConcurrentMark* _cm; 1658 BitMap* _actual_region_bm; 1659 BitMap* _actual_card_bm; 1660 1661 uint _n_workers; 1662 1663 BitMap* _expected_region_bm; 1664 BitMap* _expected_card_bm; 1665 1666 int _failures; 1667 bool _verbose; 1668 1669 public: 1670 G1ParVerifyFinalCountTask(G1CollectedHeap* g1h, 1671 BitMap* region_bm, BitMap* card_bm, 1672 BitMap* expected_region_bm, BitMap* expected_card_bm) 1673 : AbstractGangTask("G1 verify final counting"), 1674 _g1h(g1h), _cm(_g1h->concurrent_mark()), 1675 _actual_region_bm(region_bm), _actual_card_bm(card_bm), 1676 _expected_region_bm(expected_region_bm), _expected_card_bm(expected_card_bm), 1677 _failures(0), _verbose(false), 1678 _n_workers(0) { 1679 assert(VerifyDuringGC, "don't call this otherwise"); 1680 1681 // Use the value already set as the number of active threads 1682 // in the call to run_task(). 1683 if (G1CollectedHeap::use_parallel_gc_threads()) { 1684 assert( _g1h->workers()->active_workers() > 0, 1685 "Should have been previously set"); 1686 _n_workers = _g1h->workers()->active_workers(); 1687 } else { 1688 _n_workers = 1; 1689 } 1690 1691 assert(_expected_card_bm->size() == _actual_card_bm->size(), "sanity"); 1692 assert(_expected_region_bm->size() == _actual_region_bm->size(), "sanity"); 1693 1694 _verbose = _cm->verbose_medium(); 1695 } 1696 1697 void work(uint worker_id) { 1698 assert(worker_id < _n_workers, "invariant"); 1699 1700 VerifyLiveObjectDataHRClosure verify_cl(_g1h, 1701 _actual_region_bm, _actual_card_bm, 1702 _expected_region_bm, 1703 _expected_card_bm, 1704 _verbose); 1705 1706 if (G1CollectedHeap::use_parallel_gc_threads()) { 1707 _g1h->heap_region_par_iterate_chunked(&verify_cl, 1708 worker_id, 1709 _n_workers, 1710 HeapRegion::VerifyCountClaimValue); 1711 } else { 1712 _g1h->heap_region_iterate(&verify_cl); 1713 } 1714 1715 Atomic::add(verify_cl.failures(), &_failures); 1716 } 1717 1718 int failures() const { return _failures; } 1719 }; 1720 1721 // Closure that finalizes the liveness counting data. 1722 // Used during the cleanup pause. 1723 // Sets the bits corresponding to the interval [NTAMS, top] 1724 // (which contains the implicitly live objects) in the 1725 // card liveness bitmap. Also sets the bit for each region, 1726 // containing live data, in the region liveness bitmap. 1727 1728 class FinalCountDataUpdateClosure: public CMCountDataClosureBase { 1729 public: 1730 FinalCountDataUpdateClosure(G1CollectedHeap* g1h, 1731 BitMap* region_bm, 1732 BitMap* card_bm) : 1733 CMCountDataClosureBase(g1h, region_bm, card_bm) { } 1734 1735 bool doHeapRegion(HeapRegion* hr) { 1736 1737 if (hr->continuesHumongous()) { 1738 // We will ignore these here and process them when their 1739 // associated "starts humongous" region is processed (see 1740 // set_bit_for_heap_region()). Note that we cannot rely on their 1741 // associated "starts humongous" region to have their bit set to 1742 // 1 since, due to the region chunking in the parallel region 1743 // iteration, a "continues humongous" region might be visited 1744 // before its associated "starts humongous". 1745 return false; 1746 } 1747 1748 HeapWord* ntams = hr->next_top_at_mark_start(); 1749 HeapWord* top = hr->top(); 1750 1751 assert(hr->bottom() <= ntams && ntams <= hr->end(), "Preconditions."); 1752 1753 // Mark the allocated-since-marking portion... 1754 if (ntams < top) { 1755 // This definitely means the region has live objects. 1756 set_bit_for_region(hr); 1757 1758 // Now set the bits in the card bitmap for [ntams, top) 1759 BitMap::idx_t start_idx = _cm->card_bitmap_index_for(ntams); 1760 BitMap::idx_t end_idx = _cm->card_bitmap_index_for(top); 1761 1762 // Note: if we're looking at the last region in heap - top 1763 // could be actually just beyond the end of the heap; end_idx 1764 // will then correspond to a (non-existent) card that is also 1765 // just beyond the heap. 1766 if (_g1h->is_in_g1_reserved(top) && !_ct_bs->is_card_aligned(top)) { 1767 // end of object is not card aligned - increment to cover 1768 // all the cards spanned by the object 1769 end_idx += 1; 1770 } 1771 1772 assert(end_idx <= _card_bm->size(), 1773 err_msg("oob: end_idx= "SIZE_FORMAT", bitmap size= "SIZE_FORMAT, 1774 end_idx, _card_bm->size())); 1775 assert(start_idx < _card_bm->size(), 1776 err_msg("oob: start_idx= "SIZE_FORMAT", bitmap size= "SIZE_FORMAT, 1777 start_idx, _card_bm->size())); 1778 1779 _cm->set_card_bitmap_range(_card_bm, start_idx, end_idx, true /* is_par */); 1780 } 1781 1782 // Set the bit for the region if it contains live data 1783 if (hr->next_marked_bytes() > 0) { 1784 set_bit_for_region(hr); 1785 } 1786 1787 return false; 1788 } 1789 }; 1790 1791 class G1ParFinalCountTask: public AbstractGangTask { 1792 protected: 1793 G1CollectedHeap* _g1h; 1794 ConcurrentMark* _cm; 1795 BitMap* _actual_region_bm; 1796 BitMap* _actual_card_bm; 1797 1798 uint _n_workers; 1799 1800 public: 1801 G1ParFinalCountTask(G1CollectedHeap* g1h, BitMap* region_bm, BitMap* card_bm) 1802 : AbstractGangTask("G1 final counting"), 1803 _g1h(g1h), _cm(_g1h->concurrent_mark()), 1804 _actual_region_bm(region_bm), _actual_card_bm(card_bm), 1805 _n_workers(0) { 1806 // Use the value already set as the number of active threads 1807 // in the call to run_task(). 1808 if (G1CollectedHeap::use_parallel_gc_threads()) { 1809 assert( _g1h->workers()->active_workers() > 0, 1810 "Should have been previously set"); 1811 _n_workers = _g1h->workers()->active_workers(); 1812 } else { 1813 _n_workers = 1; 1814 } 1815 } 1816 1817 void work(uint worker_id) { 1818 assert(worker_id < _n_workers, "invariant"); 1819 1820 FinalCountDataUpdateClosure final_update_cl(_g1h, 1821 _actual_region_bm, 1822 _actual_card_bm); 1823 1824 if (G1CollectedHeap::use_parallel_gc_threads()) { 1825 _g1h->heap_region_par_iterate_chunked(&final_update_cl, 1826 worker_id, 1827 _n_workers, 1828 HeapRegion::FinalCountClaimValue); 1829 } else { 1830 _g1h->heap_region_iterate(&final_update_cl); 1831 } 1832 } 1833 }; 1834 1835 class G1ParNoteEndTask; 1836 1837 class G1NoteEndOfConcMarkClosure : public HeapRegionClosure { 1838 G1CollectedHeap* _g1; 1839 size_t _max_live_bytes; 1840 uint _regions_claimed; 1841 size_t _freed_bytes; 1842 FreeRegionList* _local_cleanup_list; 1843 HeapRegionSetCount _old_regions_removed; 1844 HeapRegionSetCount _humongous_regions_removed; 1845 HRRSCleanupTask* _hrrs_cleanup_task; 1846 double _claimed_region_time; 1847 double _max_region_time; 1848 1849 public: 1850 G1NoteEndOfConcMarkClosure(G1CollectedHeap* g1, 1851 FreeRegionList* local_cleanup_list, 1852 HRRSCleanupTask* hrrs_cleanup_task) : 1853 _g1(g1), 1854 _max_live_bytes(0), _regions_claimed(0), 1855 _freed_bytes(0), 1856 _claimed_region_time(0.0), _max_region_time(0.0), 1857 _local_cleanup_list(local_cleanup_list), 1858 _old_regions_removed(), 1859 _humongous_regions_removed(), 1860 _hrrs_cleanup_task(hrrs_cleanup_task) { } 1861 1862 size_t freed_bytes() { return _freed_bytes; } 1863 const HeapRegionSetCount& old_regions_removed() { return _old_regions_removed; } 1864 const HeapRegionSetCount& humongous_regions_removed() { return _humongous_regions_removed; } 1865 1866 bool doHeapRegion(HeapRegion *hr) { 1867 if (hr->continuesHumongous()) { 1868 return false; 1869 } 1870 // We use a claim value of zero here because all regions 1871 // were claimed with value 1 in the FinalCount task. 1872 _g1->reset_gc_time_stamps(hr); 1873 double start = os::elapsedTime(); 1874 _regions_claimed++; 1875 hr->note_end_of_marking(); 1876 _max_live_bytes += hr->max_live_bytes(); 1877 1878 if (hr->used() > 0 && hr->max_live_bytes() == 0 && !hr->is_young()) { 1879 _freed_bytes += hr->used(); 1880 hr->set_containing_set(NULL); 1881 if (hr->isHumongous()) { 1882 assert(hr->startsHumongous(), "we should only see starts humongous"); 1883 _humongous_regions_removed.increment(1u, hr->capacity()); 1884 _g1->free_humongous_region(hr, _local_cleanup_list, true); 1885 } else { 1886 _old_regions_removed.increment(1u, hr->capacity()); 1887 _g1->free_region(hr, _local_cleanup_list, true); 1888 } 1889 } else { 1890 hr->rem_set()->do_cleanup_work(_hrrs_cleanup_task); 1891 } 1892 1893 double region_time = (os::elapsedTime() - start); 1894 _claimed_region_time += region_time; 1895 if (region_time > _max_region_time) { 1896 _max_region_time = region_time; 1897 } 1898 return false; 1899 } 1900 1901 size_t max_live_bytes() { return _max_live_bytes; } 1902 uint regions_claimed() { return _regions_claimed; } 1903 double claimed_region_time_sec() { return _claimed_region_time; } 1904 double max_region_time_sec() { return _max_region_time; } 1905 }; 1906 1907 class G1ParNoteEndTask: public AbstractGangTask { 1908 friend class G1NoteEndOfConcMarkClosure; 1909 1910 protected: 1911 G1CollectedHeap* _g1h; 1912 size_t _max_live_bytes; 1913 size_t _freed_bytes; 1914 FreeRegionList* _cleanup_list; 1915 1916 public: 1917 G1ParNoteEndTask(G1CollectedHeap* g1h, 1918 FreeRegionList* cleanup_list) : 1919 AbstractGangTask("G1 note end"), _g1h(g1h), 1920 _max_live_bytes(0), _freed_bytes(0), _cleanup_list(cleanup_list) { } 1921 1922 void work(uint worker_id) { 1923 double start = os::elapsedTime(); 1924 FreeRegionList local_cleanup_list("Local Cleanup List"); 1925 HRRSCleanupTask hrrs_cleanup_task; 1926 G1NoteEndOfConcMarkClosure g1_note_end(_g1h, &local_cleanup_list, 1927 &hrrs_cleanup_task); 1928 if (G1CollectedHeap::use_parallel_gc_threads()) { 1929 _g1h->heap_region_par_iterate_chunked(&g1_note_end, worker_id, 1930 _g1h->workers()->active_workers(), 1931 HeapRegion::NoteEndClaimValue); 1932 } else { 1933 _g1h->heap_region_iterate(&g1_note_end); 1934 } 1935 assert(g1_note_end.complete(), "Shouldn't have yielded!"); 1936 1937 // Now update the lists 1938 _g1h->remove_from_old_sets(g1_note_end.old_regions_removed(), g1_note_end.humongous_regions_removed()); 1939 { 1940 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); 1941 _g1h->decrement_summary_bytes(g1_note_end.freed_bytes()); 1942 _max_live_bytes += g1_note_end.max_live_bytes(); 1943 _freed_bytes += g1_note_end.freed_bytes(); 1944 1945 // If we iterate over the global cleanup list at the end of 1946 // cleanup to do this printing we will not guarantee to only 1947 // generate output for the newly-reclaimed regions (the list 1948 // might not be empty at the beginning of cleanup; we might 1949 // still be working on its previous contents). So we do the 1950 // printing here, before we append the new regions to the global 1951 // cleanup list. 1952 1953 G1HRPrinter* hr_printer = _g1h->hr_printer(); 1954 if (hr_printer->is_active()) { 1955 FreeRegionListIterator iter(&local_cleanup_list); 1956 while (iter.more_available()) { 1957 HeapRegion* hr = iter.get_next(); 1958 hr_printer->cleanup(hr); 1959 } 1960 } 1961 1962 _cleanup_list->add_ordered(&local_cleanup_list); 1963 assert(local_cleanup_list.is_empty(), "post-condition"); 1964 1965 HeapRegionRemSet::finish_cleanup_task(&hrrs_cleanup_task); 1966 } 1967 } 1968 size_t max_live_bytes() { return _max_live_bytes; } 1969 size_t freed_bytes() { return _freed_bytes; } 1970 }; 1971 1972 class G1ParScrubRemSetTask: public AbstractGangTask { 1973 protected: 1974 G1RemSet* _g1rs; 1975 BitMap* _region_bm; 1976 BitMap* _card_bm; 1977 public: 1978 G1ParScrubRemSetTask(G1CollectedHeap* g1h, 1979 BitMap* region_bm, BitMap* card_bm) : 1980 AbstractGangTask("G1 ScrubRS"), _g1rs(g1h->g1_rem_set()), 1981 _region_bm(region_bm), _card_bm(card_bm) { } 1982 1983 void work(uint worker_id) { 1984 if (G1CollectedHeap::use_parallel_gc_threads()) { 1985 _g1rs->scrub_par(_region_bm, _card_bm, worker_id, 1986 HeapRegion::ScrubRemSetClaimValue); 1987 } else { 1988 _g1rs->scrub(_region_bm, _card_bm); 1989 } 1990 } 1991 1992 }; 1993 1994 void ConcurrentMark::cleanup() { 1995 // world is stopped at this checkpoint 1996 assert(SafepointSynchronize::is_at_safepoint(), 1997 "world should be stopped"); 1998 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 1999 2000 // If a full collection has happened, we shouldn't do this. 2001 if (has_aborted()) { 2002 g1h->set_marking_complete(); // So bitmap clearing isn't confused 2003 return; 2004 } 2005 2006 g1h->verify_region_sets_optional(); 2007 2008 if (VerifyDuringGC) { 2009 HandleMark hm; // handle scope 2010 Universe::heap()->prepare_for_verify(); 2011 Universe::verify(VerifyOption_G1UsePrevMarking, 2012 " VerifyDuringGC:(before)"); 2013 } 2014 g1h->check_bitmaps("Cleanup Start"); 2015 2016 G1CollectorPolicy* g1p = G1CollectedHeap::heap()->g1_policy(); 2017 g1p->record_concurrent_mark_cleanup_start(); 2018 2019 double start = os::elapsedTime(); 2020 2021 HeapRegionRemSet::reset_for_cleanup_tasks(); 2022 2023 uint n_workers; 2024 2025 // Do counting once more with the world stopped for good measure. 2026 G1ParFinalCountTask g1_par_count_task(g1h, &_region_bm, &_card_bm); 2027 2028 if (G1CollectedHeap::use_parallel_gc_threads()) { 2029 assert(g1h->check_heap_region_claim_values(HeapRegion::InitialClaimValue), 2030 "sanity check"); 2031 2032 g1h->set_par_threads(); 2033 n_workers = g1h->n_par_threads(); 2034 assert(g1h->n_par_threads() == n_workers, 2035 "Should not have been reset"); 2036 g1h->workers()->run_task(&g1_par_count_task); 2037 // Done with the parallel phase so reset to 0. 2038 g1h->set_par_threads(0); 2039 2040 assert(g1h->check_heap_region_claim_values(HeapRegion::FinalCountClaimValue), 2041 "sanity check"); 2042 } else { 2043 n_workers = 1; 2044 g1_par_count_task.work(0); 2045 } 2046 2047 if (VerifyDuringGC) { 2048 // Verify that the counting data accumulated during marking matches 2049 // that calculated by walking the marking bitmap. 2050 2051 // Bitmaps to hold expected values 2052 BitMap expected_region_bm(_region_bm.size(), true); 2053 BitMap expected_card_bm(_card_bm.size(), true); 2054 2055 G1ParVerifyFinalCountTask g1_par_verify_task(g1h, 2056 &_region_bm, 2057 &_card_bm, 2058 &expected_region_bm, 2059 &expected_card_bm); 2060 2061 if (G1CollectedHeap::use_parallel_gc_threads()) { 2062 g1h->set_par_threads((int)n_workers); 2063 g1h->workers()->run_task(&g1_par_verify_task); 2064 // Done with the parallel phase so reset to 0. 2065 g1h->set_par_threads(0); 2066 2067 assert(g1h->check_heap_region_claim_values(HeapRegion::VerifyCountClaimValue), 2068 "sanity check"); 2069 } else { 2070 g1_par_verify_task.work(0); 2071 } 2072 2073 guarantee(g1_par_verify_task.failures() == 0, "Unexpected accounting failures"); 2074 } 2075 2076 size_t start_used_bytes = g1h->used(); 2077 g1h->set_marking_complete(); 2078 2079 double count_end = os::elapsedTime(); 2080 double this_final_counting_time = (count_end - start); 2081 _total_counting_time += this_final_counting_time; 2082 2083 if (G1PrintRegionLivenessInfo) { 2084 G1PrintRegionLivenessInfoClosure cl(gclog_or_tty, "Post-Marking"); 2085 _g1h->heap_region_iterate(&cl); 2086 } 2087 2088 // Install newly created mark bitMap as "prev". 2089 swapMarkBitMaps(); 2090 2091 g1h->reset_gc_time_stamp(); 2092 2093 // Note end of marking in all heap regions. 2094 G1ParNoteEndTask g1_par_note_end_task(g1h, &_cleanup_list); 2095 if (G1CollectedHeap::use_parallel_gc_threads()) { 2096 g1h->set_par_threads((int)n_workers); 2097 g1h->workers()->run_task(&g1_par_note_end_task); 2098 g1h->set_par_threads(0); 2099 2100 assert(g1h->check_heap_region_claim_values(HeapRegion::NoteEndClaimValue), 2101 "sanity check"); 2102 } else { 2103 g1_par_note_end_task.work(0); 2104 } 2105 g1h->check_gc_time_stamps(); 2106 2107 if (!cleanup_list_is_empty()) { 2108 // The cleanup list is not empty, so we'll have to process it 2109 // concurrently. Notify anyone else that might be wanting free 2110 // regions that there will be more free regions coming soon. 2111 g1h->set_free_regions_coming(); 2112 } 2113 2114 // call below, since it affects the metric by which we sort the heap 2115 // regions. 2116 if (G1ScrubRemSets) { 2117 double rs_scrub_start = os::elapsedTime(); 2118 G1ParScrubRemSetTask g1_par_scrub_rs_task(g1h, &_region_bm, &_card_bm); 2119 if (G1CollectedHeap::use_parallel_gc_threads()) { 2120 g1h->set_par_threads((int)n_workers); 2121 g1h->workers()->run_task(&g1_par_scrub_rs_task); 2122 g1h->set_par_threads(0); 2123 2124 assert(g1h->check_heap_region_claim_values( 2125 HeapRegion::ScrubRemSetClaimValue), 2126 "sanity check"); 2127 } else { 2128 g1_par_scrub_rs_task.work(0); 2129 } 2130 2131 double rs_scrub_end = os::elapsedTime(); 2132 double this_rs_scrub_time = (rs_scrub_end - rs_scrub_start); 2133 _total_rs_scrub_time += this_rs_scrub_time; 2134 } 2135 2136 // this will also free any regions totally full of garbage objects, 2137 // and sort the regions. 2138 g1h->g1_policy()->record_concurrent_mark_cleanup_end((int)n_workers); 2139 2140 // Statistics. 2141 double end = os::elapsedTime(); 2142 _cleanup_times.add((end - start) * 1000.0); 2143 2144 if (G1Log::fine()) { 2145 g1h->print_size_transition(gclog_or_tty, 2146 start_used_bytes, 2147 g1h->used(), 2148 g1h->capacity()); 2149 } 2150 2151 // Clean up will have freed any regions completely full of garbage. 2152 // Update the soft reference policy with the new heap occupancy. 2153 Universe::update_heap_info_at_gc(); 2154 2155 if (VerifyDuringGC) { 2156 HandleMark hm; // handle scope 2157 Universe::heap()->prepare_for_verify(); 2158 Universe::verify(VerifyOption_G1UsePrevMarking, 2159 " VerifyDuringGC:(after)"); 2160 } 2161 g1h->check_bitmaps("Cleanup End"); 2162 2163 g1h->verify_region_sets_optional(); 2164 2165 // We need to make this be a "collection" so any collection pause that 2166 // races with it goes around and waits for completeCleanup to finish. 2167 g1h->increment_total_collections(); 2168 2169 // Clean out dead classes and update Metaspace sizes. 2170 if (ClassUnloadingWithConcurrentMark) { 2171 ClassLoaderDataGraph::purge(); 2172 } 2173 MetaspaceGC::compute_new_size(); 2174 2175 // We reclaimed old regions so we should calculate the sizes to make 2176 // sure we update the old gen/space data. 2177 g1h->g1mm()->update_sizes(); 2178 g1h->allocation_context_stats().update_after_mark(); 2179 2180 g1h->trace_heap_after_concurrent_cycle(); 2181 } 2182 2183 void ConcurrentMark::completeCleanup() { 2184 if (has_aborted()) return; 2185 2186 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 2187 2188 _cleanup_list.verify_optional(); 2189 FreeRegionList tmp_free_list("Tmp Free List"); 2190 2191 if (G1ConcRegionFreeingVerbose) { 2192 gclog_or_tty->print_cr("G1ConcRegionFreeing [complete cleanup] : " 2193 "cleanup list has %u entries", 2194 _cleanup_list.length()); 2195 } 2196 2197 // No one else should be accessing the _cleanup_list at this point, 2198 // so it is not necessary to take any locks 2199 while (!_cleanup_list.is_empty()) { 2200 HeapRegion* hr = _cleanup_list.remove_region(true /* from_head */); 2201 assert(hr != NULL, "Got NULL from a non-empty list"); 2202 hr->par_clear(); 2203 tmp_free_list.add_ordered(hr); 2204 2205 // Instead of adding one region at a time to the secondary_free_list, 2206 // we accumulate them in the local list and move them a few at a 2207 // time. This also cuts down on the number of notify_all() calls 2208 // we do during this process. We'll also append the local list when 2209 // _cleanup_list is empty (which means we just removed the last 2210 // region from the _cleanup_list). 2211 if ((tmp_free_list.length() % G1SecondaryFreeListAppendLength == 0) || 2212 _cleanup_list.is_empty()) { 2213 if (G1ConcRegionFreeingVerbose) { 2214 gclog_or_tty->print_cr("G1ConcRegionFreeing [complete cleanup] : " 2215 "appending %u entries to the secondary_free_list, " 2216 "cleanup list still has %u entries", 2217 tmp_free_list.length(), 2218 _cleanup_list.length()); 2219 } 2220 2221 { 2222 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 2223 g1h->secondary_free_list_add(&tmp_free_list); 2224 SecondaryFreeList_lock->notify_all(); 2225 } 2226 2227 if (G1StressConcRegionFreeing) { 2228 for (uintx i = 0; i < G1StressConcRegionFreeingDelayMillis; ++i) { 2229 os::sleep(Thread::current(), (jlong) 1, false); 2230 } 2231 } 2232 } 2233 } 2234 assert(tmp_free_list.is_empty(), "post-condition"); 2235 } 2236 2237 // Supporting Object and Oop closures for reference discovery 2238 // and processing in during marking 2239 2240 bool G1CMIsAliveClosure::do_object_b(oop obj) { 2241 HeapWord* addr = (HeapWord*)obj; 2242 return addr != NULL && 2243 (!_g1->is_in_g1_reserved(addr) || !_g1->is_obj_ill(obj)); 2244 } 2245 2246 // 'Keep Alive' oop closure used by both serial parallel reference processing. 2247 // Uses the CMTask associated with a worker thread (for serial reference 2248 // processing the CMTask for worker 0 is used) to preserve (mark) and 2249 // trace referent objects. 2250 // 2251 // Using the CMTask and embedded local queues avoids having the worker 2252 // threads operating on the global mark stack. This reduces the risk 2253 // of overflowing the stack - which we would rather avoid at this late 2254 // state. Also using the tasks' local queues removes the potential 2255 // of the workers interfering with each other that could occur if 2256 // operating on the global stack. 2257 2258 class G1CMKeepAliveAndDrainClosure: public OopClosure { 2259 ConcurrentMark* _cm; 2260 CMTask* _task; 2261 int _ref_counter_limit; 2262 int _ref_counter; 2263 bool _is_serial; 2264 public: 2265 G1CMKeepAliveAndDrainClosure(ConcurrentMark* cm, CMTask* task, bool is_serial) : 2266 _cm(cm), _task(task), _is_serial(is_serial), 2267 _ref_counter_limit(G1RefProcDrainInterval) { 2268 assert(_ref_counter_limit > 0, "sanity"); 2269 assert(!_is_serial || _task->worker_id() == 0, "only task 0 for serial code"); 2270 _ref_counter = _ref_counter_limit; 2271 } 2272 2273 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 2274 virtual void do_oop( oop* p) { do_oop_work(p); } 2275 2276 template <class T> void do_oop_work(T* p) { 2277 if (!_cm->has_overflown()) { 2278 oop obj = oopDesc::load_decode_heap_oop(p); 2279 if (_cm->verbose_high()) { 2280 gclog_or_tty->print_cr("\t[%u] we're looking at location " 2281 "*"PTR_FORMAT" = "PTR_FORMAT, 2282 _task->worker_id(), p2i(p), p2i((void*) obj)); 2283 } 2284 2285 _task->deal_with_reference(obj); 2286 _ref_counter--; 2287 2288 if (_ref_counter == 0) { 2289 // We have dealt with _ref_counter_limit references, pushing them 2290 // and objects reachable from them on to the local stack (and 2291 // possibly the global stack). Call CMTask::do_marking_step() to 2292 // process these entries. 2293 // 2294 // We call CMTask::do_marking_step() in a loop, which we'll exit if 2295 // there's nothing more to do (i.e. we're done with the entries that 2296 // were pushed as a result of the CMTask::deal_with_reference() calls 2297 // above) or we overflow. 2298 // 2299 // Note: CMTask::do_marking_step() can set the CMTask::has_aborted() 2300 // flag while there may still be some work to do. (See the comment at 2301 // the beginning of CMTask::do_marking_step() for those conditions - 2302 // one of which is reaching the specified time target.) It is only 2303 // when CMTask::do_marking_step() returns without setting the 2304 // has_aborted() flag that the marking step has completed. 2305 do { 2306 double mark_step_duration_ms = G1ConcMarkStepDurationMillis; 2307 _task->do_marking_step(mark_step_duration_ms, 2308 false /* do_termination */, 2309 _is_serial); 2310 } while (_task->has_aborted() && !_cm->has_overflown()); 2311 _ref_counter = _ref_counter_limit; 2312 } 2313 } else { 2314 if (_cm->verbose_high()) { 2315 gclog_or_tty->print_cr("\t[%u] CM Overflow", _task->worker_id()); 2316 } 2317 } 2318 } 2319 }; 2320 2321 // 'Drain' oop closure used by both serial and parallel reference processing. 2322 // Uses the CMTask associated with a given worker thread (for serial 2323 // reference processing the CMtask for worker 0 is used). Calls the 2324 // do_marking_step routine, with an unbelievably large timeout value, 2325 // to drain the marking data structures of the remaining entries 2326 // added by the 'keep alive' oop closure above. 2327 2328 class G1CMDrainMarkingStackClosure: public VoidClosure { 2329 ConcurrentMark* _cm; 2330 CMTask* _task; 2331 bool _is_serial; 2332 public: 2333 G1CMDrainMarkingStackClosure(ConcurrentMark* cm, CMTask* task, bool is_serial) : 2334 _cm(cm), _task(task), _is_serial(is_serial) { 2335 assert(!_is_serial || _task->worker_id() == 0, "only task 0 for serial code"); 2336 } 2337 2338 void do_void() { 2339 do { 2340 if (_cm->verbose_high()) { 2341 gclog_or_tty->print_cr("\t[%u] Drain: Calling do_marking_step - serial: %s", 2342 _task->worker_id(), BOOL_TO_STR(_is_serial)); 2343 } 2344 2345 // We call CMTask::do_marking_step() to completely drain the local 2346 // and global marking stacks of entries pushed by the 'keep alive' 2347 // oop closure (an instance of G1CMKeepAliveAndDrainClosure above). 2348 // 2349 // CMTask::do_marking_step() is called in a loop, which we'll exit 2350 // if there's nothing more to do (i.e. we'completely drained the 2351 // entries that were pushed as a a result of applying the 'keep alive' 2352 // closure to the entries on the discovered ref lists) or we overflow 2353 // the global marking stack. 2354 // 2355 // Note: CMTask::do_marking_step() can set the CMTask::has_aborted() 2356 // flag while there may still be some work to do. (See the comment at 2357 // the beginning of CMTask::do_marking_step() for those conditions - 2358 // one of which is reaching the specified time target.) It is only 2359 // when CMTask::do_marking_step() returns without setting the 2360 // has_aborted() flag that the marking step has completed. 2361 2362 _task->do_marking_step(1000000000.0 /* something very large */, 2363 true /* do_termination */, 2364 _is_serial); 2365 } while (_task->has_aborted() && !_cm->has_overflown()); 2366 } 2367 }; 2368 2369 // Implementation of AbstractRefProcTaskExecutor for parallel 2370 // reference processing at the end of G1 concurrent marking 2371 2372 class G1CMRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 2373 private: 2374 G1CollectedHeap* _g1h; 2375 ConcurrentMark* _cm; 2376 WorkGang* _workers; 2377 int _active_workers; 2378 2379 public: 2380 G1CMRefProcTaskExecutor(G1CollectedHeap* g1h, 2381 ConcurrentMark* cm, 2382 WorkGang* workers, 2383 int n_workers) : 2384 _g1h(g1h), _cm(cm), 2385 _workers(workers), _active_workers(n_workers) { } 2386 2387 // Executes the given task using concurrent marking worker threads. 2388 virtual void execute(ProcessTask& task); 2389 virtual void execute(EnqueueTask& task); 2390 }; 2391 2392 class G1CMRefProcTaskProxy: public AbstractGangTask { 2393 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 2394 ProcessTask& _proc_task; 2395 G1CollectedHeap* _g1h; 2396 ConcurrentMark* _cm; 2397 2398 public: 2399 G1CMRefProcTaskProxy(ProcessTask& proc_task, 2400 G1CollectedHeap* g1h, 2401 ConcurrentMark* cm) : 2402 AbstractGangTask("Process reference objects in parallel"), 2403 _proc_task(proc_task), _g1h(g1h), _cm(cm) { 2404 ReferenceProcessor* rp = _g1h->ref_processor_cm(); 2405 assert(rp->processing_is_mt(), "shouldn't be here otherwise"); 2406 } 2407 2408 virtual void work(uint worker_id) { 2409 ResourceMark rm; 2410 HandleMark hm; 2411 CMTask* task = _cm->task(worker_id); 2412 G1CMIsAliveClosure g1_is_alive(_g1h); 2413 G1CMKeepAliveAndDrainClosure g1_par_keep_alive(_cm, task, false /* is_serial */); 2414 G1CMDrainMarkingStackClosure g1_par_drain(_cm, task, false /* is_serial */); 2415 2416 _proc_task.work(worker_id, g1_is_alive, g1_par_keep_alive, g1_par_drain); 2417 } 2418 }; 2419 2420 void G1CMRefProcTaskExecutor::execute(ProcessTask& proc_task) { 2421 assert(_workers != NULL, "Need parallel worker threads."); 2422 assert(_g1h->ref_processor_cm()->processing_is_mt(), "processing is not MT"); 2423 2424 G1CMRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _cm); 2425 2426 // We need to reset the concurrency level before each 2427 // proxy task execution, so that the termination protocol 2428 // and overflow handling in CMTask::do_marking_step() knows 2429 // how many workers to wait for. 2430 _cm->set_concurrency(_active_workers); 2431 _g1h->set_par_threads(_active_workers); 2432 _workers->run_task(&proc_task_proxy); 2433 _g1h->set_par_threads(0); 2434 } 2435 2436 class G1CMRefEnqueueTaskProxy: public AbstractGangTask { 2437 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; 2438 EnqueueTask& _enq_task; 2439 2440 public: 2441 G1CMRefEnqueueTaskProxy(EnqueueTask& enq_task) : 2442 AbstractGangTask("Enqueue reference objects in parallel"), 2443 _enq_task(enq_task) { } 2444 2445 virtual void work(uint worker_id) { 2446 _enq_task.work(worker_id); 2447 } 2448 }; 2449 2450 void G1CMRefProcTaskExecutor::execute(EnqueueTask& enq_task) { 2451 assert(_workers != NULL, "Need parallel worker threads."); 2452 assert(_g1h->ref_processor_cm()->processing_is_mt(), "processing is not MT"); 2453 2454 G1CMRefEnqueueTaskProxy enq_task_proxy(enq_task); 2455 2456 // Not strictly necessary but... 2457 // 2458 // We need to reset the concurrency level before each 2459 // proxy task execution, so that the termination protocol 2460 // and overflow handling in CMTask::do_marking_step() knows 2461 // how many workers to wait for. 2462 _cm->set_concurrency(_active_workers); 2463 _g1h->set_par_threads(_active_workers); 2464 _workers->run_task(&enq_task_proxy); 2465 _g1h->set_par_threads(0); 2466 } 2467 2468 void ConcurrentMark::weakRefsWorkParallelPart(BoolObjectClosure* is_alive, bool purged_classes) { 2469 G1CollectedHeap::heap()->parallel_cleaning(is_alive, true, true, purged_classes); 2470 } 2471 2472 // Helper class to get rid of some boilerplate code. 2473 class G1RemarkGCTraceTime : public GCTraceTime { 2474 static bool doit_and_prepend(bool doit) { 2475 if (doit) { 2476 gclog_or_tty->put(' '); 2477 } 2478 return doit; 2479 } 2480 2481 public: 2482 G1RemarkGCTraceTime(const char* title, bool doit) 2483 : GCTraceTime(title, doit_and_prepend(doit), false, G1CollectedHeap::heap()->gc_timer_cm(), 2484 G1CollectedHeap::heap()->concurrent_mark()->concurrent_gc_id()) { 2485 } 2486 }; 2487 2488 void ConcurrentMark::weakRefsWork(bool clear_all_soft_refs) { 2489 if (has_overflown()) { 2490 // Skip processing the discovered references if we have 2491 // overflown the global marking stack. Reference objects 2492 // only get discovered once so it is OK to not 2493 // de-populate the discovered reference lists. We could have, 2494 // but the only benefit would be that, when marking restarts, 2495 // less reference objects are discovered. 2496 return; 2497 } 2498 2499 ResourceMark rm; 2500 HandleMark hm; 2501 2502 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 2503 2504 // Is alive closure. 2505 G1CMIsAliveClosure g1_is_alive(g1h); 2506 2507 // Inner scope to exclude the cleaning of the string and symbol 2508 // tables from the displayed time. 2509 { 2510 if (G1Log::finer()) { 2511 gclog_or_tty->put(' '); 2512 } 2513 GCTraceTime t("GC ref-proc", G1Log::finer(), false, g1h->gc_timer_cm(), concurrent_gc_id()); 2514 2515 ReferenceProcessor* rp = g1h->ref_processor_cm(); 2516 2517 // See the comment in G1CollectedHeap::ref_processing_init() 2518 // about how reference processing currently works in G1. 2519 2520 // Set the soft reference policy 2521 rp->setup_policy(clear_all_soft_refs); 2522 assert(_markStack.isEmpty(), "mark stack should be empty"); 2523 2524 // Instances of the 'Keep Alive' and 'Complete GC' closures used 2525 // in serial reference processing. Note these closures are also 2526 // used for serially processing (by the the current thread) the 2527 // JNI references during parallel reference processing. 2528 // 2529 // These closures do not need to synchronize with the worker 2530 // threads involved in parallel reference processing as these 2531 // instances are executed serially by the current thread (e.g. 2532 // reference processing is not multi-threaded and is thus 2533 // performed by the current thread instead of a gang worker). 2534 // 2535 // The gang tasks involved in parallel reference procssing create 2536 // their own instances of these closures, which do their own 2537 // synchronization among themselves. 2538 G1CMKeepAliveAndDrainClosure g1_keep_alive(this, task(0), true /* is_serial */); 2539 G1CMDrainMarkingStackClosure g1_drain_mark_stack(this, task(0), true /* is_serial */); 2540 2541 // We need at least one active thread. If reference processing 2542 // is not multi-threaded we use the current (VMThread) thread, 2543 // otherwise we use the work gang from the G1CollectedHeap and 2544 // we utilize all the worker threads we can. 2545 bool processing_is_mt = rp->processing_is_mt() && g1h->workers() != NULL; 2546 uint active_workers = (processing_is_mt ? g1h->workers()->active_workers() : 1U); 2547 active_workers = MAX2(MIN2(active_workers, _max_worker_id), 1U); 2548 2549 // Parallel processing task executor. 2550 G1CMRefProcTaskExecutor par_task_executor(g1h, this, 2551 g1h->workers(), active_workers); 2552 AbstractRefProcTaskExecutor* executor = (processing_is_mt ? &par_task_executor : NULL); 2553 2554 // Set the concurrency level. The phase was already set prior to 2555 // executing the remark task. 2556 set_concurrency(active_workers); 2557 2558 // Set the degree of MT processing here. If the discovery was done MT, 2559 // the number of threads involved during discovery could differ from 2560 // the number of active workers. This is OK as long as the discovered 2561 // Reference lists are balanced (see balance_all_queues() and balance_queues()). 2562 rp->set_active_mt_degree(active_workers); 2563 2564 // Process the weak references. 2565 const ReferenceProcessorStats& stats = 2566 rp->process_discovered_references(&g1_is_alive, 2567 &g1_keep_alive, 2568 &g1_drain_mark_stack, 2569 executor, 2570 g1h->gc_timer_cm(), 2571 concurrent_gc_id()); 2572 g1h->gc_tracer_cm()->report_gc_reference_stats(stats); 2573 2574 // The do_oop work routines of the keep_alive and drain_marking_stack 2575 // oop closures will set the has_overflown flag if we overflow the 2576 // global marking stack. 2577 2578 assert(_markStack.overflow() || _markStack.isEmpty(), 2579 "mark stack should be empty (unless it overflowed)"); 2580 2581 if (_markStack.overflow()) { 2582 // This should have been done already when we tried to push an 2583 // entry on to the global mark stack. But let's do it again. 2584 set_has_overflown(); 2585 } 2586 2587 assert(rp->num_q() == active_workers, "why not"); 2588 2589 rp->enqueue_discovered_references(executor); 2590 2591 rp->verify_no_references_recorded(); 2592 assert(!rp->discovery_enabled(), "Post condition"); 2593 } 2594 2595 if (has_overflown()) { 2596 // We can not trust g1_is_alive if the marking stack overflowed 2597 return; 2598 } 2599 2600 assert(_markStack.isEmpty(), "Marking should have completed"); 2601 2602 // Unload Klasses, String, Symbols, Code Cache, etc. 2603 { 2604 G1RemarkGCTraceTime trace("Unloading", G1Log::finer()); 2605 2606 if (ClassUnloadingWithConcurrentMark) { 2607 // Cleaning of klasses depends on correct information from MetadataMarkOnStack. The CodeCache::mark_on_stack 2608 // part is too slow to be done serially, so it is handled during the weakRefsWorkParallelPart phase. 2609 // Defer the cleaning until we have complete on_stack data. 2610 MetadataOnStackMark md_on_stack(false /* Don't visit the code cache at this point */); 2611 2612 bool purged_classes; 2613 2614 { 2615 G1RemarkGCTraceTime trace("System Dictionary Unloading", G1Log::finest()); 2616 purged_classes = SystemDictionary::do_unloading(&g1_is_alive, false /* Defer klass cleaning */); 2617 } 2618 2619 { 2620 G1RemarkGCTraceTime trace("Parallel Unloading", G1Log::finest()); 2621 weakRefsWorkParallelPart(&g1_is_alive, purged_classes); 2622 } 2623 2624 { 2625 G1RemarkGCTraceTime trace("Deallocate Metadata", G1Log::finest()); 2626 ClassLoaderDataGraph::free_deallocate_lists(); 2627 } 2628 } 2629 2630 if (G1StringDedup::is_enabled()) { 2631 G1RemarkGCTraceTime trace("String Deduplication Unlink", G1Log::finest()); 2632 G1StringDedup::unlink(&g1_is_alive); 2633 } 2634 } 2635 } 2636 2637 void ConcurrentMark::swapMarkBitMaps() { 2638 CMBitMapRO* temp = _prevMarkBitMap; 2639 _prevMarkBitMap = (CMBitMapRO*)_nextMarkBitMap; 2640 _nextMarkBitMap = (CMBitMap*) temp; 2641 } 2642 2643 class CMObjectClosure; 2644 2645 // Closure for iterating over objects, currently only used for 2646 // processing SATB buffers. 2647 class CMObjectClosure : public ObjectClosure { 2648 private: 2649 CMTask* _task; 2650 2651 public: 2652 void do_object(oop obj) { 2653 _task->deal_with_reference(obj); 2654 } 2655 2656 CMObjectClosure(CMTask* task) : _task(task) { } 2657 }; 2658 2659 class G1RemarkThreadsClosure : public ThreadClosure { 2660 CMObjectClosure _cm_obj; 2661 G1CMOopClosure _cm_cl; 2662 MarkingCodeBlobClosure _code_cl; 2663 int _thread_parity; 2664 bool _is_par; 2665 2666 public: 2667 G1RemarkThreadsClosure(G1CollectedHeap* g1h, CMTask* task, bool is_par) : 2668 _cm_obj(task), _cm_cl(g1h, g1h->concurrent_mark(), task), _code_cl(&_cm_cl, !CodeBlobToOopClosure::FixRelocations), 2669 _thread_parity(SharedHeap::heap()->strong_roots_parity()), _is_par(is_par) {} 2670 2671 void do_thread(Thread* thread) { 2672 if (thread->is_Java_thread()) { 2673 if (thread->claim_oops_do(_is_par, _thread_parity)) { 2674 JavaThread* jt = (JavaThread*)thread; 2675 2676 // In theory it should not be neccessary to explicitly walk the nmethods to find roots for concurrent marking 2677 // however the liveness of oops reachable from nmethods have very complex lifecycles: 2678 // * Alive if on the stack of an executing method 2679 // * Weakly reachable otherwise 2680 // Some objects reachable from nmethods, such as the class loader (or klass_holder) of the receiver should be 2681 // live by the SATB invariant but other oops recorded in nmethods may behave differently. 2682 jt->nmethods_do(&_code_cl); 2683 2684 jt->satb_mark_queue().apply_closure_and_empty(&_cm_obj); 2685 } 2686 } else if (thread->is_VM_thread()) { 2687 if (thread->claim_oops_do(_is_par, _thread_parity)) { 2688 JavaThread::satb_mark_queue_set().shared_satb_queue()->apply_closure_and_empty(&_cm_obj); 2689 } 2690 } 2691 } 2692 }; 2693 2694 class CMRemarkTask: public AbstractGangTask { 2695 private: 2696 ConcurrentMark* _cm; 2697 bool _is_serial; 2698 public: 2699 void work(uint worker_id) { 2700 // Since all available tasks are actually started, we should 2701 // only proceed if we're supposed to be actived. 2702 if (worker_id < _cm->active_tasks()) { 2703 CMTask* task = _cm->task(worker_id); 2704 task->record_start_time(); 2705 { 2706 ResourceMark rm; 2707 HandleMark hm; 2708 2709 G1RemarkThreadsClosure threads_f(G1CollectedHeap::heap(), task, !_is_serial); 2710 Threads::threads_do(&threads_f); 2711 } 2712 2713 do { 2714 task->do_marking_step(1000000000.0 /* something very large */, 2715 true /* do_termination */, 2716 _is_serial); 2717 } while (task->has_aborted() && !_cm->has_overflown()); 2718 // If we overflow, then we do not want to restart. We instead 2719 // want to abort remark and do concurrent marking again. 2720 task->record_end_time(); 2721 } 2722 } 2723 2724 CMRemarkTask(ConcurrentMark* cm, int active_workers, bool is_serial) : 2725 AbstractGangTask("Par Remark"), _cm(cm), _is_serial(is_serial) { 2726 _cm->terminator()->reset_for_reuse(active_workers); 2727 } 2728 }; 2729 2730 void ConcurrentMark::checkpointRootsFinalWork() { 2731 ResourceMark rm; 2732 HandleMark hm; 2733 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 2734 2735 G1RemarkGCTraceTime trace("Finalize Marking", G1Log::finer()); 2736 2737 g1h->ensure_parsability(false); 2738 2739 if (G1CollectedHeap::use_parallel_gc_threads()) { 2740 G1CollectedHeap::StrongRootsScope srs(g1h); 2741 // this is remark, so we'll use up all active threads 2742 uint active_workers = g1h->workers()->active_workers(); 2743 if (active_workers == 0) { 2744 assert(active_workers > 0, "Should have been set earlier"); 2745 active_workers = (uint) ParallelGCThreads; 2746 g1h->workers()->set_active_workers(active_workers); 2747 } 2748 set_concurrency_and_phase(active_workers, false /* concurrent */); 2749 // Leave _parallel_marking_threads at it's 2750 // value originally calculated in the ConcurrentMark 2751 // constructor and pass values of the active workers 2752 // through the gang in the task. 2753 2754 CMRemarkTask remarkTask(this, active_workers, false /* is_serial */); 2755 // We will start all available threads, even if we decide that the 2756 // active_workers will be fewer. The extra ones will just bail out 2757 // immediately. 2758 g1h->set_par_threads(active_workers); 2759 g1h->workers()->run_task(&remarkTask); 2760 g1h->set_par_threads(0); 2761 } else { 2762 G1CollectedHeap::StrongRootsScope srs(g1h); 2763 uint active_workers = 1; 2764 set_concurrency_and_phase(active_workers, false /* concurrent */); 2765 2766 // Note - if there's no work gang then the VMThread will be 2767 // the thread to execute the remark - serially. We have 2768 // to pass true for the is_serial parameter so that 2769 // CMTask::do_marking_step() doesn't enter the sync 2770 // barriers in the event of an overflow. Doing so will 2771 // cause an assert that the current thread is not a 2772 // concurrent GC thread. 2773 CMRemarkTask remarkTask(this, active_workers, true /* is_serial*/); 2774 remarkTask.work(0); 2775 } 2776 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set(); 2777 guarantee(has_overflown() || 2778 satb_mq_set.completed_buffers_num() == 0, 2779 err_msg("Invariant: has_overflown = %s, num buffers = %d", 2780 BOOL_TO_STR(has_overflown()), 2781 satb_mq_set.completed_buffers_num())); 2782 2783 print_stats(); 2784 } 2785 2786 #ifndef PRODUCT 2787 2788 class PrintReachableOopClosure: public OopClosure { 2789 private: 2790 G1CollectedHeap* _g1h; 2791 outputStream* _out; 2792 VerifyOption _vo; 2793 bool _all; 2794 2795 public: 2796 PrintReachableOopClosure(outputStream* out, 2797 VerifyOption vo, 2798 bool all) : 2799 _g1h(G1CollectedHeap::heap()), 2800 _out(out), _vo(vo), _all(all) { } 2801 2802 void do_oop(narrowOop* p) { do_oop_work(p); } 2803 void do_oop( oop* p) { do_oop_work(p); } 2804 2805 template <class T> void do_oop_work(T* p) { 2806 oop obj = oopDesc::load_decode_heap_oop(p); 2807 const char* str = NULL; 2808 const char* str2 = ""; 2809 2810 if (obj == NULL) { 2811 str = ""; 2812 } else if (!_g1h->is_in_g1_reserved(obj)) { 2813 str = " O"; 2814 } else { 2815 HeapRegion* hr = _g1h->heap_region_containing(obj); 2816 bool over_tams = _g1h->allocated_since_marking(obj, hr, _vo); 2817 bool marked = _g1h->is_marked(obj, _vo); 2818 2819 if (over_tams) { 2820 str = " >"; 2821 if (marked) { 2822 str2 = " AND MARKED"; 2823 } 2824 } else if (marked) { 2825 str = " M"; 2826 } else { 2827 str = " NOT"; 2828 } 2829 } 2830 2831 _out->print_cr(" "PTR_FORMAT": "PTR_FORMAT"%s%s", 2832 p2i(p), p2i((void*) obj), str, str2); 2833 } 2834 }; 2835 2836 class PrintReachableObjectClosure : public ObjectClosure { 2837 private: 2838 G1CollectedHeap* _g1h; 2839 outputStream* _out; 2840 VerifyOption _vo; 2841 bool _all; 2842 HeapRegion* _hr; 2843 2844 public: 2845 PrintReachableObjectClosure(outputStream* out, 2846 VerifyOption vo, 2847 bool all, 2848 HeapRegion* hr) : 2849 _g1h(G1CollectedHeap::heap()), 2850 _out(out), _vo(vo), _all(all), _hr(hr) { } 2851 2852 void do_object(oop o) { 2853 bool over_tams = _g1h->allocated_since_marking(o, _hr, _vo); 2854 bool marked = _g1h->is_marked(o, _vo); 2855 bool print_it = _all || over_tams || marked; 2856 2857 if (print_it) { 2858 _out->print_cr(" "PTR_FORMAT"%s", 2859 p2i((void *)o), (over_tams) ? " >" : (marked) ? " M" : ""); 2860 PrintReachableOopClosure oopCl(_out, _vo, _all); 2861 o->oop_iterate_no_header(&oopCl); 2862 } 2863 } 2864 }; 2865 2866 class PrintReachableRegionClosure : public HeapRegionClosure { 2867 private: 2868 G1CollectedHeap* _g1h; 2869 outputStream* _out; 2870 VerifyOption _vo; 2871 bool _all; 2872 2873 public: 2874 bool doHeapRegion(HeapRegion* hr) { 2875 HeapWord* b = hr->bottom(); 2876 HeapWord* e = hr->end(); 2877 HeapWord* t = hr->top(); 2878 HeapWord* p = _g1h->top_at_mark_start(hr, _vo); 2879 _out->print_cr("** ["PTR_FORMAT", "PTR_FORMAT"] top: "PTR_FORMAT" " 2880 "TAMS: " PTR_FORMAT, p2i(b), p2i(e), p2i(t), p2i(p)); 2881 _out->cr(); 2882 2883 HeapWord* from = b; 2884 HeapWord* to = t; 2885 2886 if (to > from) { 2887 _out->print_cr("Objects in [" PTR_FORMAT ", " PTR_FORMAT "]", p2i(from), p2i(to)); 2888 _out->cr(); 2889 PrintReachableObjectClosure ocl(_out, _vo, _all, hr); 2890 hr->object_iterate_mem_careful(MemRegion(from, to), &ocl); 2891 _out->cr(); 2892 } 2893 2894 return false; 2895 } 2896 2897 PrintReachableRegionClosure(outputStream* out, 2898 VerifyOption vo, 2899 bool all) : 2900 _g1h(G1CollectedHeap::heap()), _out(out), _vo(vo), _all(all) { } 2901 }; 2902 2903 void ConcurrentMark::print_reachable(const char* str, 2904 VerifyOption vo, 2905 bool all) { 2906 gclog_or_tty->cr(); 2907 gclog_or_tty->print_cr("== Doing heap dump... "); 2908 2909 if (G1PrintReachableBaseFile == NULL) { 2910 gclog_or_tty->print_cr(" #### error: no base file defined"); 2911 return; 2912 } 2913 2914 if (strlen(G1PrintReachableBaseFile) + 1 + strlen(str) > 2915 (JVM_MAXPATHLEN - 1)) { 2916 gclog_or_tty->print_cr(" #### error: file name too long"); 2917 return; 2918 } 2919 2920 char file_name[JVM_MAXPATHLEN]; 2921 sprintf(file_name, "%s.%s", G1PrintReachableBaseFile, str); 2922 gclog_or_tty->print_cr(" dumping to file %s", file_name); 2923 2924 fileStream fout(file_name); 2925 if (!fout.is_open()) { 2926 gclog_or_tty->print_cr(" #### error: could not open file"); 2927 return; 2928 } 2929 2930 outputStream* out = &fout; 2931 out->print_cr("-- USING %s", _g1h->top_at_mark_start_str(vo)); 2932 out->cr(); 2933 2934 out->print_cr("--- ITERATING OVER REGIONS"); 2935 out->cr(); 2936 PrintReachableRegionClosure rcl(out, vo, all); 2937 _g1h->heap_region_iterate(&rcl); 2938 out->cr(); 2939 2940 gclog_or_tty->print_cr(" done"); 2941 gclog_or_tty->flush(); 2942 } 2943 2944 #endif // PRODUCT 2945 2946 void ConcurrentMark::clearRangePrevBitmap(MemRegion mr) { 2947 // Note we are overriding the read-only view of the prev map here, via 2948 // the cast. 2949 ((CMBitMap*)_prevMarkBitMap)->clearRange(mr); 2950 } 2951 2952 void ConcurrentMark::clearRangeNextBitmap(MemRegion mr) { 2953 _nextMarkBitMap->clearRange(mr); 2954 } 2955 2956 HeapRegion* 2957 ConcurrentMark::claim_region(uint worker_id) { 2958 // "checkpoint" the finger 2959 HeapWord* finger = _finger; 2960 2961 // _heap_end will not change underneath our feet; it only changes at 2962 // yield points. 2963 while (finger < _heap_end) { 2964 assert(_g1h->is_in_g1_reserved(finger), "invariant"); 2965 2966 // Note on how this code handles humongous regions. In the 2967 // normal case the finger will reach the start of a "starts 2968 // humongous" (SH) region. Its end will either be the end of the 2969 // last "continues humongous" (CH) region in the sequence, or the 2970 // standard end of the SH region (if the SH is the only region in 2971 // the sequence). That way claim_region() will skip over the CH 2972 // regions. However, there is a subtle race between a CM thread 2973 // executing this method and a mutator thread doing a humongous 2974 // object allocation. The two are not mutually exclusive as the CM 2975 // thread does not need to hold the Heap_lock when it gets 2976 // here. So there is a chance that claim_region() will come across 2977 // a free region that's in the progress of becoming a SH or a CH 2978 // region. In the former case, it will either 2979 // a) Miss the update to the region's end, in which case it will 2980 // visit every subsequent CH region, will find their bitmaps 2981 // empty, and do nothing, or 2982 // b) Will observe the update of the region's end (in which case 2983 // it will skip the subsequent CH regions). 2984 // If it comes across a region that suddenly becomes CH, the 2985 // scenario will be similar to b). So, the race between 2986 // claim_region() and a humongous object allocation might force us 2987 // to do a bit of unnecessary work (due to some unnecessary bitmap 2988 // iterations) but it should not introduce and correctness issues. 2989 HeapRegion* curr_region = _g1h->heap_region_containing_raw(finger); 2990 2991 // Above heap_region_containing_raw may return NULL as we always scan claim 2992 // until the end of the heap. In this case, just jump to the next region. 2993 HeapWord* end = curr_region != NULL ? curr_region->end() : finger + HeapRegion::GrainWords; 2994 2995 // Is the gap between reading the finger and doing the CAS too long? 2996 HeapWord* res = (HeapWord*) Atomic::cmpxchg_ptr(end, &_finger, finger); 2997 if (res == finger && curr_region != NULL) { 2998 // we succeeded 2999 HeapWord* bottom = curr_region->bottom(); 3000 HeapWord* limit = curr_region->next_top_at_mark_start(); 3001 3002 if (verbose_low()) { 3003 gclog_or_tty->print_cr("[%u] curr_region = "PTR_FORMAT" " 3004 "["PTR_FORMAT", "PTR_FORMAT"), " 3005 "limit = "PTR_FORMAT, 3006 worker_id, p2i(curr_region), p2i(bottom), p2i(end), p2i(limit)); 3007 } 3008 3009 // notice that _finger == end cannot be guaranteed here since, 3010 // someone else might have moved the finger even further 3011 assert(_finger >= end, "the finger should have moved forward"); 3012 3013 if (verbose_low()) { 3014 gclog_or_tty->print_cr("[%u] we were successful with region = " 3015 PTR_FORMAT, worker_id, p2i(curr_region)); 3016 } 3017 3018 if (limit > bottom) { 3019 if (verbose_low()) { 3020 gclog_or_tty->print_cr("[%u] region "PTR_FORMAT" is not empty, " 3021 "returning it ", worker_id, p2i(curr_region)); 3022 } 3023 return curr_region; 3024 } else { 3025 assert(limit == bottom, 3026 "the region limit should be at bottom"); 3027 if (verbose_low()) { 3028 gclog_or_tty->print_cr("[%u] region "PTR_FORMAT" is empty, " 3029 "returning NULL", worker_id, p2i(curr_region)); 3030 } 3031 // we return NULL and the caller should try calling 3032 // claim_region() again. 3033 return NULL; 3034 } 3035 } else { 3036 assert(_finger > finger, "the finger should have moved forward"); 3037 if (verbose_low()) { 3038 if (curr_region == NULL) { 3039 gclog_or_tty->print_cr("[%u] found uncommitted region, moving finger, " 3040 "global finger = "PTR_FORMAT", " 3041 "our finger = "PTR_FORMAT, 3042 worker_id, p2i(_finger), p2i(finger)); 3043 } else { 3044 gclog_or_tty->print_cr("[%u] somebody else moved the finger, " 3045 "global finger = "PTR_FORMAT", " 3046 "our finger = "PTR_FORMAT, 3047 worker_id, p2i(_finger), p2i(finger)); 3048 } 3049 } 3050 3051 // read it again 3052 finger = _finger; 3053 } 3054 } 3055 3056 return NULL; 3057 } 3058 3059 #ifndef PRODUCT 3060 enum VerifyNoCSetOopsPhase { 3061 VerifyNoCSetOopsStack, 3062 VerifyNoCSetOopsQueues 3063 }; 3064 3065 class VerifyNoCSetOopsClosure : public OopClosure, public ObjectClosure { 3066 private: 3067 G1CollectedHeap* _g1h; 3068 VerifyNoCSetOopsPhase _phase; 3069 int _info; 3070 3071 const char* phase_str() { 3072 switch (_phase) { 3073 case VerifyNoCSetOopsStack: return "Stack"; 3074 case VerifyNoCSetOopsQueues: return "Queue"; 3075 default: ShouldNotReachHere(); 3076 } 3077 return NULL; 3078 } 3079 3080 void do_object_work(oop obj) { 3081 guarantee(!_g1h->obj_in_cs(obj), 3082 err_msg("obj: "PTR_FORMAT" in CSet, phase: %s, info: %d", 3083 p2i((void*) obj), phase_str(), _info)); 3084 } 3085 3086 public: 3087 VerifyNoCSetOopsClosure() : _g1h(G1CollectedHeap::heap()) { } 3088 3089 void set_phase(VerifyNoCSetOopsPhase phase, int info = -1) { 3090 _phase = phase; 3091 _info = info; 3092 } 3093 3094 virtual void do_oop(oop* p) { 3095 oop obj = oopDesc::load_decode_heap_oop(p); 3096 do_object_work(obj); 3097 } 3098 3099 virtual void do_oop(narrowOop* p) { 3100 // We should not come across narrow oops while scanning marking 3101 // stacks 3102 ShouldNotReachHere(); 3103 } 3104 3105 virtual void do_object(oop obj) { 3106 do_object_work(obj); 3107 } 3108 }; 3109 3110 void ConcurrentMark::verify_no_cset_oops() { 3111 assert(SafepointSynchronize::is_at_safepoint(), "should be at a safepoint"); 3112 if (!G1CollectedHeap::heap()->mark_in_progress()) { 3113 return; 3114 } 3115 3116 VerifyNoCSetOopsClosure cl; 3117 3118 // Verify entries on the global mark stack 3119 cl.set_phase(VerifyNoCSetOopsStack); 3120 _markStack.oops_do(&cl); 3121 3122 // Verify entries on the task queues 3123 for (uint i = 0; i < _max_worker_id; i += 1) { 3124 cl.set_phase(VerifyNoCSetOopsQueues, i); 3125 CMTaskQueue* queue = _task_queues->queue(i); 3126 queue->oops_do(&cl); 3127 } 3128 3129 // Verify the global finger 3130 HeapWord* global_finger = finger(); 3131 if (global_finger != NULL && global_finger < _heap_end) { 3132 // The global finger always points to a heap region boundary. We 3133 // use heap_region_containing_raw() to get the containing region 3134 // given that the global finger could be pointing to a free region 3135 // which subsequently becomes continues humongous. If that 3136 // happens, heap_region_containing() will return the bottom of the 3137 // corresponding starts humongous region and the check below will 3138 // not hold any more. 3139 // Since we always iterate over all regions, we might get a NULL HeapRegion 3140 // here. 3141 HeapRegion* global_hr = _g1h->heap_region_containing_raw(global_finger); 3142 guarantee(global_hr == NULL || global_finger == global_hr->bottom(), 3143 err_msg("global finger: "PTR_FORMAT" region: "HR_FORMAT, 3144 p2i(global_finger), HR_FORMAT_PARAMS(global_hr))); 3145 } 3146 3147 // Verify the task fingers 3148 assert(parallel_marking_threads() <= _max_worker_id, "sanity"); 3149 for (int i = 0; i < (int) parallel_marking_threads(); i += 1) { 3150 CMTask* task = _tasks[i]; 3151 HeapWord* task_finger = task->finger(); 3152 if (task_finger != NULL && task_finger < _heap_end) { 3153 // See above note on the global finger verification. 3154 HeapRegion* task_hr = _g1h->heap_region_containing_raw(task_finger); 3155 guarantee(task_hr == NULL || task_finger == task_hr->bottom() || 3156 !task_hr->in_collection_set(), 3157 err_msg("task finger: "PTR_FORMAT" region: "HR_FORMAT, 3158 p2i(task_finger), HR_FORMAT_PARAMS(task_hr))); 3159 } 3160 } 3161 } 3162 #endif // PRODUCT 3163 3164 // Aggregate the counting data that was constructed concurrently 3165 // with marking. 3166 class AggregateCountDataHRClosure: public HeapRegionClosure { 3167 G1CollectedHeap* _g1h; 3168 ConcurrentMark* _cm; 3169 CardTableModRefBS* _ct_bs; 3170 BitMap* _cm_card_bm; 3171 uint _max_worker_id; 3172 3173 public: 3174 AggregateCountDataHRClosure(G1CollectedHeap* g1h, 3175 BitMap* cm_card_bm, 3176 uint max_worker_id) : 3177 _g1h(g1h), _cm(g1h->concurrent_mark()), 3178 _ct_bs((CardTableModRefBS*) (g1h->barrier_set())), 3179 _cm_card_bm(cm_card_bm), _max_worker_id(max_worker_id) { } 3180 3181 bool doHeapRegion(HeapRegion* hr) { 3182 if (hr->continuesHumongous()) { 3183 // We will ignore these here and process them when their 3184 // associated "starts humongous" region is processed. 3185 // Note that we cannot rely on their associated 3186 // "starts humongous" region to have their bit set to 1 3187 // since, due to the region chunking in the parallel region 3188 // iteration, a "continues humongous" region might be visited 3189 // before its associated "starts humongous". 3190 return false; 3191 } 3192 3193 HeapWord* start = hr->bottom(); 3194 HeapWord* limit = hr->next_top_at_mark_start(); 3195 HeapWord* end = hr->end(); 3196 3197 assert(start <= limit && limit <= hr->top() && hr->top() <= hr->end(), 3198 err_msg("Preconditions not met - " 3199 "start: "PTR_FORMAT", limit: "PTR_FORMAT", " 3200 "top: "PTR_FORMAT", end: "PTR_FORMAT, 3201 p2i(start), p2i(limit), p2i(hr->top()), p2i(hr->end()))); 3202 3203 assert(hr->next_marked_bytes() == 0, "Precondition"); 3204 3205 if (start == limit) { 3206 // NTAMS of this region has not been set so nothing to do. 3207 return false; 3208 } 3209 3210 // 'start' should be in the heap. 3211 assert(_g1h->is_in_g1_reserved(start) && _ct_bs->is_card_aligned(start), "sanity"); 3212 // 'end' *may* be just beyone the end of the heap (if hr is the last region) 3213 assert(!_g1h->is_in_g1_reserved(end) || _ct_bs->is_card_aligned(end), "sanity"); 3214 3215 BitMap::idx_t start_idx = _cm->card_bitmap_index_for(start); 3216 BitMap::idx_t limit_idx = _cm->card_bitmap_index_for(limit); 3217 BitMap::idx_t end_idx = _cm->card_bitmap_index_for(end); 3218 3219 // If ntams is not card aligned then we bump card bitmap index 3220 // for limit so that we get the all the cards spanned by 3221 // the object ending at ntams. 3222 // Note: if this is the last region in the heap then ntams 3223 // could be actually just beyond the end of the the heap; 3224 // limit_idx will then correspond to a (non-existent) card 3225 // that is also outside the heap. 3226 if (_g1h->is_in_g1_reserved(limit) && !_ct_bs->is_card_aligned(limit)) { 3227 limit_idx += 1; 3228 } 3229 3230 assert(limit_idx <= end_idx, "or else use atomics"); 3231 3232 // Aggregate the "stripe" in the count data associated with hr. 3233 uint hrm_index = hr->hrm_index(); 3234 size_t marked_bytes = 0; 3235 3236 for (uint i = 0; i < _max_worker_id; i += 1) { 3237 size_t* marked_bytes_array = _cm->count_marked_bytes_array_for(i); 3238 BitMap* task_card_bm = _cm->count_card_bitmap_for(i); 3239 3240 // Fetch the marked_bytes in this region for task i and 3241 // add it to the running total for this region. 3242 marked_bytes += marked_bytes_array[hrm_index]; 3243 3244 // Now union the bitmaps[0,max_worker_id)[start_idx..limit_idx) 3245 // into the global card bitmap. 3246 BitMap::idx_t scan_idx = task_card_bm->get_next_one_offset(start_idx, limit_idx); 3247 3248 while (scan_idx < limit_idx) { 3249 assert(task_card_bm->at(scan_idx) == true, "should be"); 3250 _cm_card_bm->set_bit(scan_idx); 3251 assert(_cm_card_bm->at(scan_idx) == true, "should be"); 3252 3253 // BitMap::get_next_one_offset() can handle the case when 3254 // its left_offset parameter is greater than its right_offset 3255 // parameter. It does, however, have an early exit if 3256 // left_offset == right_offset. So let's limit the value 3257 // passed in for left offset here. 3258 BitMap::idx_t next_idx = MIN2(scan_idx + 1, limit_idx); 3259 scan_idx = task_card_bm->get_next_one_offset(next_idx, limit_idx); 3260 } 3261 } 3262 3263 // Update the marked bytes for this region. 3264 hr->add_to_marked_bytes(marked_bytes); 3265 3266 // Next heap region 3267 return false; 3268 } 3269 }; 3270 3271 class G1AggregateCountDataTask: public AbstractGangTask { 3272 protected: 3273 G1CollectedHeap* _g1h; 3274 ConcurrentMark* _cm; 3275 BitMap* _cm_card_bm; 3276 uint _max_worker_id; 3277 int _active_workers; 3278 3279 public: 3280 G1AggregateCountDataTask(G1CollectedHeap* g1h, 3281 ConcurrentMark* cm, 3282 BitMap* cm_card_bm, 3283 uint max_worker_id, 3284 int n_workers) : 3285 AbstractGangTask("Count Aggregation"), 3286 _g1h(g1h), _cm(cm), _cm_card_bm(cm_card_bm), 3287 _max_worker_id(max_worker_id), 3288 _active_workers(n_workers) { } 3289 3290 void work(uint worker_id) { 3291 AggregateCountDataHRClosure cl(_g1h, _cm_card_bm, _max_worker_id); 3292 3293 if (G1CollectedHeap::use_parallel_gc_threads()) { 3294 _g1h->heap_region_par_iterate_chunked(&cl, worker_id, 3295 _active_workers, 3296 HeapRegion::AggregateCountClaimValue); 3297 } else { 3298 _g1h->heap_region_iterate(&cl); 3299 } 3300 } 3301 }; 3302 3303 3304 void ConcurrentMark::aggregate_count_data() { 3305 int n_workers = (G1CollectedHeap::use_parallel_gc_threads() ? 3306 _g1h->workers()->active_workers() : 3307 1); 3308 3309 G1AggregateCountDataTask g1_par_agg_task(_g1h, this, &_card_bm, 3310 _max_worker_id, n_workers); 3311 3312 if (G1CollectedHeap::use_parallel_gc_threads()) { 3313 assert(_g1h->check_heap_region_claim_values(HeapRegion::InitialClaimValue), 3314 "sanity check"); 3315 _g1h->set_par_threads(n_workers); 3316 _g1h->workers()->run_task(&g1_par_agg_task); 3317 _g1h->set_par_threads(0); 3318 3319 assert(_g1h->check_heap_region_claim_values(HeapRegion::AggregateCountClaimValue), 3320 "sanity check"); 3321 _g1h->reset_heap_region_claim_values(); 3322 } else { 3323 g1_par_agg_task.work(0); 3324 } 3325 } 3326 3327 // Clear the per-worker arrays used to store the per-region counting data 3328 void ConcurrentMark::clear_all_count_data() { 3329 // Clear the global card bitmap - it will be filled during 3330 // liveness count aggregation (during remark) and the 3331 // final counting task. 3332 _card_bm.clear(); 3333 3334 // Clear the global region bitmap - it will be filled as part 3335 // of the final counting task. 3336 _region_bm.clear(); 3337 3338 uint max_regions = _g1h->max_regions(); 3339 assert(_max_worker_id > 0, "uninitialized"); 3340 3341 for (uint i = 0; i < _max_worker_id; i += 1) { 3342 BitMap* task_card_bm = count_card_bitmap_for(i); 3343 size_t* marked_bytes_array = count_marked_bytes_array_for(i); 3344 3345 assert(task_card_bm->size() == _card_bm.size(), "size mismatch"); 3346 assert(marked_bytes_array != NULL, "uninitialized"); 3347 3348 memset(marked_bytes_array, 0, (size_t) max_regions * sizeof(size_t)); 3349 task_card_bm->clear(); 3350 } 3351 } 3352 3353 void ConcurrentMark::print_stats() { 3354 if (verbose_stats()) { 3355 gclog_or_tty->print_cr("---------------------------------------------------------------------"); 3356 for (size_t i = 0; i < _active_tasks; ++i) { 3357 _tasks[i]->print_stats(); 3358 gclog_or_tty->print_cr("---------------------------------------------------------------------"); 3359 } 3360 } 3361 } 3362 3363 // abandon current marking iteration due to a Full GC 3364 void ConcurrentMark::abort() { 3365 // Clear all marks in the next bitmap for the next marking cycle. This will allow us to skip the next 3366 // concurrent bitmap clearing. 3367 _nextMarkBitMap->clearAll(); 3368 3369 // Note we cannot clear the previous marking bitmap here 3370 // since VerifyDuringGC verifies the objects marked during 3371 // a full GC against the previous bitmap. 3372 3373 // Clear the liveness counting data 3374 clear_all_count_data(); 3375 // Empty mark stack 3376 reset_marking_state(); 3377 for (uint i = 0; i < _max_worker_id; ++i) { 3378 _tasks[i]->clear_region_fields(); 3379 } 3380 _first_overflow_barrier_sync.abort(); 3381 _second_overflow_barrier_sync.abort(); 3382 const GCId& gc_id = _g1h->gc_tracer_cm()->gc_id(); 3383 if (!gc_id.is_undefined()) { 3384 // We can do multiple full GCs before ConcurrentMarkThread::run() gets a chance 3385 // to detect that it was aborted. Only keep track of the first GC id that we aborted. 3386 _aborted_gc_id = gc_id; 3387 } 3388 _has_aborted = true; 3389 3390 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set(); 3391 satb_mq_set.abandon_partial_marking(); 3392 // This can be called either during or outside marking, we'll read 3393 // the expected_active value from the SATB queue set. 3394 satb_mq_set.set_active_all_threads( 3395 false, /* new active value */ 3396 satb_mq_set.is_active() /* expected_active */); 3397 3398 _g1h->trace_heap_after_concurrent_cycle(); 3399 _g1h->register_concurrent_cycle_end(); 3400 } 3401 3402 const GCId& ConcurrentMark::concurrent_gc_id() { 3403 if (has_aborted()) { 3404 return _aborted_gc_id; 3405 } 3406 return _g1h->gc_tracer_cm()->gc_id(); 3407 } 3408 3409 static void print_ms_time_info(const char* prefix, const char* name, 3410 NumberSeq& ns) { 3411 gclog_or_tty->print_cr("%s%5d %12s: total time = %8.2f s (avg = %8.2f ms).", 3412 prefix, ns.num(), name, ns.sum()/1000.0, ns.avg()); 3413 if (ns.num() > 0) { 3414 gclog_or_tty->print_cr("%s [std. dev = %8.2f ms, max = %8.2f ms]", 3415 prefix, ns.sd(), ns.maximum()); 3416 } 3417 } 3418 3419 void ConcurrentMark::print_summary_info() { 3420 gclog_or_tty->print_cr(" Concurrent marking:"); 3421 print_ms_time_info(" ", "init marks", _init_times); 3422 print_ms_time_info(" ", "remarks", _remark_times); 3423 { 3424 print_ms_time_info(" ", "final marks", _remark_mark_times); 3425 print_ms_time_info(" ", "weak refs", _remark_weak_ref_times); 3426 3427 } 3428 print_ms_time_info(" ", "cleanups", _cleanup_times); 3429 gclog_or_tty->print_cr(" Final counting total time = %8.2f s (avg = %8.2f ms).", 3430 _total_counting_time, 3431 (_cleanup_times.num() > 0 ? _total_counting_time * 1000.0 / 3432 (double)_cleanup_times.num() 3433 : 0.0)); 3434 if (G1ScrubRemSets) { 3435 gclog_or_tty->print_cr(" RS scrub total time = %8.2f s (avg = %8.2f ms).", 3436 _total_rs_scrub_time, 3437 (_cleanup_times.num() > 0 ? _total_rs_scrub_time * 1000.0 / 3438 (double)_cleanup_times.num() 3439 : 0.0)); 3440 } 3441 gclog_or_tty->print_cr(" Total stop_world time = %8.2f s.", 3442 (_init_times.sum() + _remark_times.sum() + 3443 _cleanup_times.sum())/1000.0); 3444 gclog_or_tty->print_cr(" Total concurrent time = %8.2f s " 3445 "(%8.2f s marking).", 3446 cmThread()->vtime_accum(), 3447 cmThread()->vtime_mark_accum()); 3448 } 3449 3450 void ConcurrentMark::print_worker_threads_on(outputStream* st) const { 3451 if (use_parallel_marking_threads()) { 3452 _parallel_workers->print_worker_threads_on(st); 3453 } 3454 } 3455 3456 void ConcurrentMark::print_on_error(outputStream* st) const { 3457 st->print_cr("Marking Bits (Prev, Next): (CMBitMap*) " PTR_FORMAT ", (CMBitMap*) " PTR_FORMAT, 3458 p2i(_prevMarkBitMap), p2i(_nextMarkBitMap)); 3459 _prevMarkBitMap->print_on_error(st, " Prev Bits: "); 3460 _nextMarkBitMap->print_on_error(st, " Next Bits: "); 3461 } 3462 3463 // We take a break if someone is trying to stop the world. 3464 bool ConcurrentMark::do_yield_check(uint worker_id) { 3465 if (SuspendibleThreadSet::should_yield()) { 3466 if (worker_id == 0) { 3467 _g1h->g1_policy()->record_concurrent_pause(); 3468 } 3469 SuspendibleThreadSet::yield(); 3470 return true; 3471 } else { 3472 return false; 3473 } 3474 } 3475 3476 #ifndef PRODUCT 3477 // for debugging purposes 3478 void ConcurrentMark::print_finger() { 3479 gclog_or_tty->print_cr("heap ["PTR_FORMAT", "PTR_FORMAT"), global finger = "PTR_FORMAT, 3480 p2i(_heap_start), p2i(_heap_end), p2i(_finger)); 3481 for (uint i = 0; i < _max_worker_id; ++i) { 3482 gclog_or_tty->print(" %u: " PTR_FORMAT, i, p2i(_tasks[i]->finger())); 3483 } 3484 gclog_or_tty->cr(); 3485 } 3486 #endif 3487 3488 template<bool scan> 3489 inline void CMTask::process_grey_object(oop obj) { 3490 assert(scan || obj->is_typeArray(), "Skipping scan of grey non-typeArray"); 3491 assert(_nextMarkBitMap->isMarked((HeapWord*) obj), "invariant"); 3492 3493 if (_cm->verbose_high()) { 3494 gclog_or_tty->print_cr("[%u] processing grey object " PTR_FORMAT, 3495 _worker_id, p2i((void*) obj)); 3496 } 3497 3498 size_t obj_size = obj->size(); 3499 _words_scanned += obj_size; 3500 3501 if (scan) { 3502 obj->oop_iterate(_cm_oop_closure); 3503 } 3504 statsOnly( ++_objs_scanned ); 3505 check_limits(); 3506 } 3507 3508 template void CMTask::process_grey_object<true>(oop); 3509 template void CMTask::process_grey_object<false>(oop); 3510 3511 // Closure for iteration over bitmaps 3512 class CMBitMapClosure : public BitMapClosure { 3513 private: 3514 // the bitmap that is being iterated over 3515 CMBitMap* _nextMarkBitMap; 3516 ConcurrentMark* _cm; 3517 CMTask* _task; 3518 3519 public: 3520 CMBitMapClosure(CMTask *task, ConcurrentMark* cm, CMBitMap* nextMarkBitMap) : 3521 _task(task), _cm(cm), _nextMarkBitMap(nextMarkBitMap) { } 3522 3523 bool do_bit(size_t offset) { 3524 HeapWord* addr = _nextMarkBitMap->offsetToHeapWord(offset); 3525 assert(_nextMarkBitMap->isMarked(addr), "invariant"); 3526 assert( addr < _cm->finger(), "invariant"); 3527 3528 statsOnly( _task->increase_objs_found_on_bitmap() ); 3529 assert(addr >= _task->finger(), "invariant"); 3530 3531 // We move that task's local finger along. 3532 _task->move_finger_to(addr); 3533 3534 _task->scan_object(oop(addr)); 3535 // we only partially drain the local queue and global stack 3536 _task->drain_local_queue(true); 3537 _task->drain_global_stack(true); 3538 3539 // if the has_aborted flag has been raised, we need to bail out of 3540 // the iteration 3541 return !_task->has_aborted(); 3542 } 3543 }; 3544 3545 G1CMOopClosure::G1CMOopClosure(G1CollectedHeap* g1h, 3546 ConcurrentMark* cm, 3547 CMTask* task) 3548 : _g1h(g1h), _cm(cm), _task(task) { 3549 assert(_ref_processor == NULL, "should be initialized to NULL"); 3550 3551 if (G1UseConcMarkReferenceProcessing) { 3552 _ref_processor = g1h->ref_processor_cm(); 3553 assert(_ref_processor != NULL, "should not be NULL"); 3554 } 3555 } 3556 3557 void CMTask::setup_for_region(HeapRegion* hr) { 3558 assert(hr != NULL, 3559 "claim_region() should have filtered out NULL regions"); 3560 assert(!hr->continuesHumongous(), 3561 "claim_region() should have filtered out continues humongous regions"); 3562 3563 if (_cm->verbose_low()) { 3564 gclog_or_tty->print_cr("[%u] setting up for region "PTR_FORMAT, 3565 _worker_id, p2i(hr)); 3566 } 3567 3568 _curr_region = hr; 3569 _finger = hr->bottom(); 3570 update_region_limit(); 3571 } 3572 3573 void CMTask::update_region_limit() { 3574 HeapRegion* hr = _curr_region; 3575 HeapWord* bottom = hr->bottom(); 3576 HeapWord* limit = hr->next_top_at_mark_start(); 3577 3578 if (limit == bottom) { 3579 if (_cm->verbose_low()) { 3580 gclog_or_tty->print_cr("[%u] found an empty region " 3581 "["PTR_FORMAT", "PTR_FORMAT")", 3582 _worker_id, p2i(bottom), p2i(limit)); 3583 } 3584 // The region was collected underneath our feet. 3585 // We set the finger to bottom to ensure that the bitmap 3586 // iteration that will follow this will not do anything. 3587 // (this is not a condition that holds when we set the region up, 3588 // as the region is not supposed to be empty in the first place) 3589 _finger = bottom; 3590 } else if (limit >= _region_limit) { 3591 assert(limit >= _finger, "peace of mind"); 3592 } else { 3593 assert(limit < _region_limit, "only way to get here"); 3594 // This can happen under some pretty unusual circumstances. An 3595 // evacuation pause empties the region underneath our feet (NTAMS 3596 // at bottom). We then do some allocation in the region (NTAMS 3597 // stays at bottom), followed by the region being used as a GC 3598 // alloc region (NTAMS will move to top() and the objects 3599 // originally below it will be grayed). All objects now marked in 3600 // the region are explicitly grayed, if below the global finger, 3601 // and we do not need in fact to scan anything else. So, we simply 3602 // set _finger to be limit to ensure that the bitmap iteration 3603 // doesn't do anything. 3604 _finger = limit; 3605 } 3606 3607 _region_limit = limit; 3608 } 3609 3610 void CMTask::giveup_current_region() { 3611 assert(_curr_region != NULL, "invariant"); 3612 if (_cm->verbose_low()) { 3613 gclog_or_tty->print_cr("[%u] giving up region "PTR_FORMAT, 3614 _worker_id, p2i(_curr_region)); 3615 } 3616 clear_region_fields(); 3617 } 3618 3619 void CMTask::clear_region_fields() { 3620 // Values for these three fields that indicate that we're not 3621 // holding on to a region. 3622 _curr_region = NULL; 3623 _finger = NULL; 3624 _region_limit = NULL; 3625 } 3626 3627 void CMTask::set_cm_oop_closure(G1CMOopClosure* cm_oop_closure) { 3628 if (cm_oop_closure == NULL) { 3629 assert(_cm_oop_closure != NULL, "invariant"); 3630 } else { 3631 assert(_cm_oop_closure == NULL, "invariant"); 3632 } 3633 _cm_oop_closure = cm_oop_closure; 3634 } 3635 3636 void CMTask::reset(CMBitMap* nextMarkBitMap) { 3637 guarantee(nextMarkBitMap != NULL, "invariant"); 3638 3639 if (_cm->verbose_low()) { 3640 gclog_or_tty->print_cr("[%u] resetting", _worker_id); 3641 } 3642 3643 _nextMarkBitMap = nextMarkBitMap; 3644 clear_region_fields(); 3645 3646 _calls = 0; 3647 _elapsed_time_ms = 0.0; 3648 _termination_time_ms = 0.0; 3649 _termination_start_time_ms = 0.0; 3650 3651 #if _MARKING_STATS_ 3652 _local_pushes = 0; 3653 _local_pops = 0; 3654 _local_max_size = 0; 3655 _objs_scanned = 0; 3656 _global_pushes = 0; 3657 _global_pops = 0; 3658 _global_max_size = 0; 3659 _global_transfers_to = 0; 3660 _global_transfers_from = 0; 3661 _regions_claimed = 0; 3662 _objs_found_on_bitmap = 0; 3663 _satb_buffers_processed = 0; 3664 _steal_attempts = 0; 3665 _steals = 0; 3666 _aborted = 0; 3667 _aborted_overflow = 0; 3668 _aborted_cm_aborted = 0; 3669 _aborted_yield = 0; 3670 _aborted_timed_out = 0; 3671 _aborted_satb = 0; 3672 _aborted_termination = 0; 3673 #endif // _MARKING_STATS_ 3674 } 3675 3676 bool CMTask::should_exit_termination() { 3677 regular_clock_call(); 3678 // This is called when we are in the termination protocol. We should 3679 // quit if, for some reason, this task wants to abort or the global 3680 // stack is not empty (this means that we can get work from it). 3681 return !_cm->mark_stack_empty() || has_aborted(); 3682 } 3683 3684 void CMTask::reached_limit() { 3685 assert(_words_scanned >= _words_scanned_limit || 3686 _refs_reached >= _refs_reached_limit , 3687 "shouldn't have been called otherwise"); 3688 regular_clock_call(); 3689 } 3690 3691 void CMTask::regular_clock_call() { 3692 if (has_aborted()) return; 3693 3694 // First, we need to recalculate the words scanned and refs reached 3695 // limits for the next clock call. 3696 recalculate_limits(); 3697 3698 // During the regular clock call we do the following 3699 3700 // (1) If an overflow has been flagged, then we abort. 3701 if (_cm->has_overflown()) { 3702 set_has_aborted(); 3703 return; 3704 } 3705 3706 // If we are not concurrent (i.e. we're doing remark) we don't need 3707 // to check anything else. The other steps are only needed during 3708 // the concurrent marking phase. 3709 if (!concurrent()) return; 3710 3711 // (2) If marking has been aborted for Full GC, then we also abort. 3712 if (_cm->has_aborted()) { 3713 set_has_aborted(); 3714 statsOnly( ++_aborted_cm_aborted ); 3715 return; 3716 } 3717 3718 double curr_time_ms = os::elapsedVTime() * 1000.0; 3719 3720 // (3) If marking stats are enabled, then we update the step history. 3721 #if _MARKING_STATS_ 3722 if (_words_scanned >= _words_scanned_limit) { 3723 ++_clock_due_to_scanning; 3724 } 3725 if (_refs_reached >= _refs_reached_limit) { 3726 ++_clock_due_to_marking; 3727 } 3728 3729 double last_interval_ms = curr_time_ms - _interval_start_time_ms; 3730 _interval_start_time_ms = curr_time_ms; 3731 _all_clock_intervals_ms.add(last_interval_ms); 3732 3733 if (_cm->verbose_medium()) { 3734 gclog_or_tty->print_cr("[%u] regular clock, interval = %1.2lfms, " 3735 "scanned = "SIZE_FORMAT"%s, refs reached = "SIZE_FORMAT"%s", 3736 _worker_id, last_interval_ms, 3737 _words_scanned, 3738 (_words_scanned >= _words_scanned_limit) ? " (*)" : "", 3739 _refs_reached, 3740 (_refs_reached >= _refs_reached_limit) ? " (*)" : ""); 3741 } 3742 #endif // _MARKING_STATS_ 3743 3744 // (4) We check whether we should yield. If we have to, then we abort. 3745 if (SuspendibleThreadSet::should_yield()) { 3746 // We should yield. To do this we abort the task. The caller is 3747 // responsible for yielding. 3748 set_has_aborted(); 3749 statsOnly( ++_aborted_yield ); 3750 return; 3751 } 3752 3753 // (5) We check whether we've reached our time quota. If we have, 3754 // then we abort. 3755 double elapsed_time_ms = curr_time_ms - _start_time_ms; 3756 if (elapsed_time_ms > _time_target_ms) { 3757 set_has_aborted(); 3758 _has_timed_out = true; 3759 statsOnly( ++_aborted_timed_out ); 3760 return; 3761 } 3762 3763 // (6) Finally, we check whether there are enough completed STAB 3764 // buffers available for processing. If there are, we abort. 3765 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set(); 3766 if (!_draining_satb_buffers && satb_mq_set.process_completed_buffers()) { 3767 if (_cm->verbose_low()) { 3768 gclog_or_tty->print_cr("[%u] aborting to deal with pending SATB buffers", 3769 _worker_id); 3770 } 3771 // we do need to process SATB buffers, we'll abort and restart 3772 // the marking task to do so 3773 set_has_aborted(); 3774 statsOnly( ++_aborted_satb ); 3775 return; 3776 } 3777 } 3778 3779 void CMTask::recalculate_limits() { 3780 _real_words_scanned_limit = _words_scanned + words_scanned_period; 3781 _words_scanned_limit = _real_words_scanned_limit; 3782 3783 _real_refs_reached_limit = _refs_reached + refs_reached_period; 3784 _refs_reached_limit = _real_refs_reached_limit; 3785 } 3786 3787 void CMTask::decrease_limits() { 3788 // This is called when we believe that we're going to do an infrequent 3789 // operation which will increase the per byte scanned cost (i.e. move 3790 // entries to/from the global stack). It basically tries to decrease the 3791 // scanning limit so that the clock is called earlier. 3792 3793 if (_cm->verbose_medium()) { 3794 gclog_or_tty->print_cr("[%u] decreasing limits", _worker_id); 3795 } 3796 3797 _words_scanned_limit = _real_words_scanned_limit - 3798 3 * words_scanned_period / 4; 3799 _refs_reached_limit = _real_refs_reached_limit - 3800 3 * refs_reached_period / 4; 3801 } 3802 3803 void CMTask::move_entries_to_global_stack() { 3804 // local array where we'll store the entries that will be popped 3805 // from the local queue 3806 oop buffer[global_stack_transfer_size]; 3807 3808 int n = 0; 3809 oop obj; 3810 while (n < global_stack_transfer_size && _task_queue->pop_local(obj)) { 3811 buffer[n] = obj; 3812 ++n; 3813 } 3814 3815 if (n > 0) { 3816 // we popped at least one entry from the local queue 3817 3818 statsOnly( ++_global_transfers_to; _local_pops += n ); 3819 3820 if (!_cm->mark_stack_push(buffer, n)) { 3821 if (_cm->verbose_low()) { 3822 gclog_or_tty->print_cr("[%u] aborting due to global stack overflow", 3823 _worker_id); 3824 } 3825 set_has_aborted(); 3826 } else { 3827 // the transfer was successful 3828 3829 if (_cm->verbose_medium()) { 3830 gclog_or_tty->print_cr("[%u] pushed %d entries to the global stack", 3831 _worker_id, n); 3832 } 3833 statsOnly( int tmp_size = _cm->mark_stack_size(); 3834 if (tmp_size > _global_max_size) { 3835 _global_max_size = tmp_size; 3836 } 3837 _global_pushes += n ); 3838 } 3839 } 3840 3841 // this operation was quite expensive, so decrease the limits 3842 decrease_limits(); 3843 } 3844 3845 void CMTask::get_entries_from_global_stack() { 3846 // local array where we'll store the entries that will be popped 3847 // from the global stack. 3848 oop buffer[global_stack_transfer_size]; 3849 int n; 3850 _cm->mark_stack_pop(buffer, global_stack_transfer_size, &n); 3851 assert(n <= global_stack_transfer_size, 3852 "we should not pop more than the given limit"); 3853 if (n > 0) { 3854 // yes, we did actually pop at least one entry 3855 3856 statsOnly( ++_global_transfers_from; _global_pops += n ); 3857 if (_cm->verbose_medium()) { 3858 gclog_or_tty->print_cr("[%u] popped %d entries from the global stack", 3859 _worker_id, n); 3860 } 3861 for (int i = 0; i < n; ++i) { 3862 bool success = _task_queue->push(buffer[i]); 3863 // We only call this when the local queue is empty or under a 3864 // given target limit. So, we do not expect this push to fail. 3865 assert(success, "invariant"); 3866 } 3867 3868 statsOnly( int tmp_size = _task_queue->size(); 3869 if (tmp_size > _local_max_size) { 3870 _local_max_size = tmp_size; 3871 } 3872 _local_pushes += n ); 3873 } 3874 3875 // this operation was quite expensive, so decrease the limits 3876 decrease_limits(); 3877 } 3878 3879 void CMTask::drain_local_queue(bool partially) { 3880 if (has_aborted()) return; 3881 3882 // Decide what the target size is, depending whether we're going to 3883 // drain it partially (so that other tasks can steal if they run out 3884 // of things to do) or totally (at the very end). 3885 size_t target_size; 3886 if (partially) { 3887 target_size = MIN2((size_t)_task_queue->max_elems()/3, GCDrainStackTargetSize); 3888 } else { 3889 target_size = 0; 3890 } 3891 3892 if (_task_queue->size() > target_size) { 3893 if (_cm->verbose_high()) { 3894 gclog_or_tty->print_cr("[%u] draining local queue, target size = " SIZE_FORMAT, 3895 _worker_id, target_size); 3896 } 3897 3898 oop obj; 3899 bool ret = _task_queue->pop_local(obj); 3900 while (ret) { 3901 statsOnly( ++_local_pops ); 3902 3903 if (_cm->verbose_high()) { 3904 gclog_or_tty->print_cr("[%u] popped "PTR_FORMAT, _worker_id, 3905 p2i((void*) obj)); 3906 } 3907 3908 assert(_g1h->is_in_g1_reserved((HeapWord*) obj), "invariant" ); 3909 assert(!_g1h->is_on_master_free_list( 3910 _g1h->heap_region_containing((HeapWord*) obj)), "invariant"); 3911 3912 scan_object(obj); 3913 3914 if (_task_queue->size() <= target_size || has_aborted()) { 3915 ret = false; 3916 } else { 3917 ret = _task_queue->pop_local(obj); 3918 } 3919 } 3920 3921 if (_cm->verbose_high()) { 3922 gclog_or_tty->print_cr("[%u] drained local queue, size = %d", 3923 _worker_id, _task_queue->size()); 3924 } 3925 } 3926 } 3927 3928 void CMTask::drain_global_stack(bool partially) { 3929 if (has_aborted()) return; 3930 3931 // We have a policy to drain the local queue before we attempt to 3932 // drain the global stack. 3933 assert(partially || _task_queue->size() == 0, "invariant"); 3934 3935 // Decide what the target size is, depending whether we're going to 3936 // drain it partially (so that other tasks can steal if they run out 3937 // of things to do) or totally (at the very end). Notice that, 3938 // because we move entries from the global stack in chunks or 3939 // because another task might be doing the same, we might in fact 3940 // drop below the target. But, this is not a problem. 3941 size_t target_size; 3942 if (partially) { 3943 target_size = _cm->partial_mark_stack_size_target(); 3944 } else { 3945 target_size = 0; 3946 } 3947 3948 if (_cm->mark_stack_size() > target_size) { 3949 if (_cm->verbose_low()) { 3950 gclog_or_tty->print_cr("[%u] draining global_stack, target size " SIZE_FORMAT, 3951 _worker_id, target_size); 3952 } 3953 3954 while (!has_aborted() && _cm->mark_stack_size() > target_size) { 3955 get_entries_from_global_stack(); 3956 drain_local_queue(partially); 3957 } 3958 3959 if (_cm->verbose_low()) { 3960 gclog_or_tty->print_cr("[%u] drained global stack, size = " SIZE_FORMAT, 3961 _worker_id, _cm->mark_stack_size()); 3962 } 3963 } 3964 } 3965 3966 // SATB Queue has several assumptions on whether to call the par or 3967 // non-par versions of the methods. this is why some of the code is 3968 // replicated. We should really get rid of the single-threaded version 3969 // of the code to simplify things. 3970 void CMTask::drain_satb_buffers() { 3971 if (has_aborted()) return; 3972 3973 // We set this so that the regular clock knows that we're in the 3974 // middle of draining buffers and doesn't set the abort flag when it 3975 // notices that SATB buffers are available for draining. It'd be 3976 // very counter productive if it did that. :-) 3977 _draining_satb_buffers = true; 3978 3979 CMObjectClosure oc(this); 3980 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set(); 3981 3982 // This keeps claiming and applying the closure to completed buffers 3983 // until we run out of buffers or we need to abort. 3984 while (!has_aborted() && 3985 satb_mq_set.apply_closure_to_completed_buffer(&oc)) { 3986 if (_cm->verbose_medium()) { 3987 gclog_or_tty->print_cr("[%u] processed an SATB buffer", _worker_id); 3988 } 3989 statsOnly( ++_satb_buffers_processed ); 3990 regular_clock_call(); 3991 } 3992 3993 _draining_satb_buffers = false; 3994 3995 assert(has_aborted() || 3996 concurrent() || 3997 satb_mq_set.completed_buffers_num() == 0, "invariant"); 3998 3999 // again, this was a potentially expensive operation, decrease the 4000 // limits to get the regular clock call early 4001 decrease_limits(); 4002 } 4003 4004 void CMTask::print_stats() { 4005 gclog_or_tty->print_cr("Marking Stats, task = %u, calls = %d", 4006 _worker_id, _calls); 4007 gclog_or_tty->print_cr(" Elapsed time = %1.2lfms, Termination time = %1.2lfms", 4008 _elapsed_time_ms, _termination_time_ms); 4009 gclog_or_tty->print_cr(" Step Times (cum): num = %d, avg = %1.2lfms, sd = %1.2lfms", 4010 _step_times_ms.num(), _step_times_ms.avg(), 4011 _step_times_ms.sd()); 4012 gclog_or_tty->print_cr(" max = %1.2lfms, total = %1.2lfms", 4013 _step_times_ms.maximum(), _step_times_ms.sum()); 4014 4015 #if _MARKING_STATS_ 4016 gclog_or_tty->print_cr(" Clock Intervals (cum): num = %d, avg = %1.2lfms, sd = %1.2lfms", 4017 _all_clock_intervals_ms.num(), _all_clock_intervals_ms.avg(), 4018 _all_clock_intervals_ms.sd()); 4019 gclog_or_tty->print_cr(" max = %1.2lfms, total = %1.2lfms", 4020 _all_clock_intervals_ms.maximum(), 4021 _all_clock_intervals_ms.sum()); 4022 gclog_or_tty->print_cr(" Clock Causes (cum): scanning = %d, marking = %d", 4023 _clock_due_to_scanning, _clock_due_to_marking); 4024 gclog_or_tty->print_cr(" Objects: scanned = %d, found on the bitmap = %d", 4025 _objs_scanned, _objs_found_on_bitmap); 4026 gclog_or_tty->print_cr(" Local Queue: pushes = %d, pops = %d, max size = %d", 4027 _local_pushes, _local_pops, _local_max_size); 4028 gclog_or_tty->print_cr(" Global Stack: pushes = %d, pops = %d, max size = %d", 4029 _global_pushes, _global_pops, _global_max_size); 4030 gclog_or_tty->print_cr(" transfers to = %d, transfers from = %d", 4031 _global_transfers_to,_global_transfers_from); 4032 gclog_or_tty->print_cr(" Regions: claimed = %d", _regions_claimed); 4033 gclog_or_tty->print_cr(" SATB buffers: processed = %d", _satb_buffers_processed); 4034 gclog_or_tty->print_cr(" Steals: attempts = %d, successes = %d", 4035 _steal_attempts, _steals); 4036 gclog_or_tty->print_cr(" Aborted: %d, due to", _aborted); 4037 gclog_or_tty->print_cr(" overflow: %d, global abort: %d, yield: %d", 4038 _aborted_overflow, _aborted_cm_aborted, _aborted_yield); 4039 gclog_or_tty->print_cr(" time out: %d, SATB: %d, termination: %d", 4040 _aborted_timed_out, _aborted_satb, _aborted_termination); 4041 #endif // _MARKING_STATS_ 4042 } 4043 4044 /***************************************************************************** 4045 4046 The do_marking_step(time_target_ms, ...) method is the building 4047 block of the parallel marking framework. It can be called in parallel 4048 with other invocations of do_marking_step() on different tasks 4049 (but only one per task, obviously) and concurrently with the 4050 mutator threads, or during remark, hence it eliminates the need 4051 for two versions of the code. When called during remark, it will 4052 pick up from where the task left off during the concurrent marking 4053 phase. Interestingly, tasks are also claimable during evacuation 4054 pauses too, since do_marking_step() ensures that it aborts before 4055 it needs to yield. 4056 4057 The data structures that it uses to do marking work are the 4058 following: 4059 4060 (1) Marking Bitmap. If there are gray objects that appear only 4061 on the bitmap (this happens either when dealing with an overflow 4062 or when the initial marking phase has simply marked the roots 4063 and didn't push them on the stack), then tasks claim heap 4064 regions whose bitmap they then scan to find gray objects. A 4065 global finger indicates where the end of the last claimed region 4066 is. A local finger indicates how far into the region a task has 4067 scanned. The two fingers are used to determine how to gray an 4068 object (i.e. whether simply marking it is OK, as it will be 4069 visited by a task in the future, or whether it needs to be also 4070 pushed on a stack). 4071 4072 (2) Local Queue. The local queue of the task which is accessed 4073 reasonably efficiently by the task. Other tasks can steal from 4074 it when they run out of work. Throughout the marking phase, a 4075 task attempts to keep its local queue short but not totally 4076 empty, so that entries are available for stealing by other 4077 tasks. Only when there is no more work, a task will totally 4078 drain its local queue. 4079 4080 (3) Global Mark Stack. This handles local queue overflow. During 4081 marking only sets of entries are moved between it and the local 4082 queues, as access to it requires a mutex and more fine-grain 4083 interaction with it which might cause contention. If it 4084 overflows, then the marking phase should restart and iterate 4085 over the bitmap to identify gray objects. Throughout the marking 4086 phase, tasks attempt to keep the global mark stack at a small 4087 length but not totally empty, so that entries are available for 4088 popping by other tasks. Only when there is no more work, tasks 4089 will totally drain the global mark stack. 4090 4091 (4) SATB Buffer Queue. This is where completed SATB buffers are 4092 made available. Buffers are regularly removed from this queue 4093 and scanned for roots, so that the queue doesn't get too 4094 long. During remark, all completed buffers are processed, as 4095 well as the filled in parts of any uncompleted buffers. 4096 4097 The do_marking_step() method tries to abort when the time target 4098 has been reached. There are a few other cases when the 4099 do_marking_step() method also aborts: 4100 4101 (1) When the marking phase has been aborted (after a Full GC). 4102 4103 (2) When a global overflow (on the global stack) has been 4104 triggered. Before the task aborts, it will actually sync up with 4105 the other tasks to ensure that all the marking data structures 4106 (local queues, stacks, fingers etc.) are re-initialized so that 4107 when do_marking_step() completes, the marking phase can 4108 immediately restart. 4109 4110 (3) When enough completed SATB buffers are available. The 4111 do_marking_step() method only tries to drain SATB buffers right 4112 at the beginning. So, if enough buffers are available, the 4113 marking step aborts and the SATB buffers are processed at 4114 the beginning of the next invocation. 4115 4116 (4) To yield. when we have to yield then we abort and yield 4117 right at the end of do_marking_step(). This saves us from a lot 4118 of hassle as, by yielding we might allow a Full GC. If this 4119 happens then objects will be compacted underneath our feet, the 4120 heap might shrink, etc. We save checking for this by just 4121 aborting and doing the yield right at the end. 4122 4123 From the above it follows that the do_marking_step() method should 4124 be called in a loop (or, otherwise, regularly) until it completes. 4125 4126 If a marking step completes without its has_aborted() flag being 4127 true, it means it has completed the current marking phase (and 4128 also all other marking tasks have done so and have all synced up). 4129 4130 A method called regular_clock_call() is invoked "regularly" (in 4131 sub ms intervals) throughout marking. It is this clock method that 4132 checks all the abort conditions which were mentioned above and 4133 decides when the task should abort. A work-based scheme is used to 4134 trigger this clock method: when the number of object words the 4135 marking phase has scanned or the number of references the marking 4136 phase has visited reach a given limit. Additional invocations to 4137 the method clock have been planted in a few other strategic places 4138 too. The initial reason for the clock method was to avoid calling 4139 vtime too regularly, as it is quite expensive. So, once it was in 4140 place, it was natural to piggy-back all the other conditions on it 4141 too and not constantly check them throughout the code. 4142 4143 If do_termination is true then do_marking_step will enter its 4144 termination protocol. 4145 4146 The value of is_serial must be true when do_marking_step is being 4147 called serially (i.e. by the VMThread) and do_marking_step should 4148 skip any synchronization in the termination and overflow code. 4149 Examples include the serial remark code and the serial reference 4150 processing closures. 4151 4152 The value of is_serial must be false when do_marking_step is 4153 being called by any of the worker threads in a work gang. 4154 Examples include the concurrent marking code (CMMarkingTask), 4155 the MT remark code, and the MT reference processing closures. 4156 4157 *****************************************************************************/ 4158 4159 void CMTask::do_marking_step(double time_target_ms, 4160 bool do_termination, 4161 bool is_serial) { 4162 assert(time_target_ms >= 1.0, "minimum granularity is 1ms"); 4163 assert(concurrent() == _cm->concurrent(), "they should be the same"); 4164 4165 G1CollectorPolicy* g1_policy = _g1h->g1_policy(); 4166 assert(_task_queues != NULL, "invariant"); 4167 assert(_task_queue != NULL, "invariant"); 4168 assert(_task_queues->queue(_worker_id) == _task_queue, "invariant"); 4169 4170 assert(!_claimed, 4171 "only one thread should claim this task at any one time"); 4172 4173 // OK, this doesn't safeguard again all possible scenarios, as it is 4174 // possible for two threads to set the _claimed flag at the same 4175 // time. But it is only for debugging purposes anyway and it will 4176 // catch most problems. 4177 _claimed = true; 4178 4179 _start_time_ms = os::elapsedVTime() * 1000.0; 4180 statsOnly( _interval_start_time_ms = _start_time_ms ); 4181 4182 // If do_stealing is true then do_marking_step will attempt to 4183 // steal work from the other CMTasks. It only makes sense to 4184 // enable stealing when the termination protocol is enabled 4185 // and do_marking_step() is not being called serially. 4186 bool do_stealing = do_termination && !is_serial; 4187 4188 double diff_prediction_ms = 4189 g1_policy->get_new_prediction(&_marking_step_diffs_ms); 4190 _time_target_ms = time_target_ms - diff_prediction_ms; 4191 4192 // set up the variables that are used in the work-based scheme to 4193 // call the regular clock method 4194 _words_scanned = 0; 4195 _refs_reached = 0; 4196 recalculate_limits(); 4197 4198 // clear all flags 4199 clear_has_aborted(); 4200 _has_timed_out = false; 4201 _draining_satb_buffers = false; 4202 4203 ++_calls; 4204 4205 if (_cm->verbose_low()) { 4206 gclog_or_tty->print_cr("[%u] >>>>>>>>>> START, call = %d, " 4207 "target = %1.2lfms >>>>>>>>>>", 4208 _worker_id, _calls, _time_target_ms); 4209 } 4210 4211 // Set up the bitmap and oop closures. Anything that uses them is 4212 // eventually called from this method, so it is OK to allocate these 4213 // statically. 4214 CMBitMapClosure bitmap_closure(this, _cm, _nextMarkBitMap); 4215 G1CMOopClosure cm_oop_closure(_g1h, _cm, this); 4216 set_cm_oop_closure(&cm_oop_closure); 4217 4218 if (_cm->has_overflown()) { 4219 // This can happen if the mark stack overflows during a GC pause 4220 // and this task, after a yield point, restarts. We have to abort 4221 // as we need to get into the overflow protocol which happens 4222 // right at the end of this task. 4223 set_has_aborted(); 4224 } 4225 4226 // First drain any available SATB buffers. After this, we will not 4227 // look at SATB buffers before the next invocation of this method. 4228 // If enough completed SATB buffers are queued up, the regular clock 4229 // will abort this task so that it restarts. 4230 drain_satb_buffers(); 4231 // ...then partially drain the local queue and the global stack 4232 drain_local_queue(true); 4233 drain_global_stack(true); 4234 4235 do { 4236 if (!has_aborted() && _curr_region != NULL) { 4237 // This means that we're already holding on to a region. 4238 assert(_finger != NULL, "if region is not NULL, then the finger " 4239 "should not be NULL either"); 4240 4241 // We might have restarted this task after an evacuation pause 4242 // which might have evacuated the region we're holding on to 4243 // underneath our feet. Let's read its limit again to make sure 4244 // that we do not iterate over a region of the heap that 4245 // contains garbage (update_region_limit() will also move 4246 // _finger to the start of the region if it is found empty). 4247 update_region_limit(); 4248 // We will start from _finger not from the start of the region, 4249 // as we might be restarting this task after aborting half-way 4250 // through scanning this region. In this case, _finger points to 4251 // the address where we last found a marked object. If this is a 4252 // fresh region, _finger points to start(). 4253 MemRegion mr = MemRegion(_finger, _region_limit); 4254 4255 if (_cm->verbose_low()) { 4256 gclog_or_tty->print_cr("[%u] we're scanning part " 4257 "["PTR_FORMAT", "PTR_FORMAT") " 4258 "of region "HR_FORMAT, 4259 _worker_id, p2i(_finger), p2i(_region_limit), 4260 HR_FORMAT_PARAMS(_curr_region)); 4261 } 4262 4263 assert(!_curr_region->isHumongous() || mr.start() == _curr_region->bottom(), 4264 "humongous regions should go around loop once only"); 4265 4266 // Some special cases: 4267 // If the memory region is empty, we can just give up the region. 4268 // If the current region is humongous then we only need to check 4269 // the bitmap for the bit associated with the start of the object, 4270 // scan the object if it's live, and give up the region. 4271 // Otherwise, let's iterate over the bitmap of the part of the region 4272 // that is left. 4273 // If the iteration is successful, give up the region. 4274 if (mr.is_empty()) { 4275 giveup_current_region(); 4276 regular_clock_call(); 4277 } else if (_curr_region->isHumongous() && mr.start() == _curr_region->bottom()) { 4278 if (_nextMarkBitMap->isMarked(mr.start())) { 4279 // The object is marked - apply the closure 4280 BitMap::idx_t offset = _nextMarkBitMap->heapWordToOffset(mr.start()); 4281 bitmap_closure.do_bit(offset); 4282 } 4283 // Even if this task aborted while scanning the humongous object 4284 // we can (and should) give up the current region. 4285 giveup_current_region(); 4286 regular_clock_call(); 4287 } else if (_nextMarkBitMap->iterate(&bitmap_closure, mr)) { 4288 giveup_current_region(); 4289 regular_clock_call(); 4290 } else { 4291 assert(has_aborted(), "currently the only way to do so"); 4292 // The only way to abort the bitmap iteration is to return 4293 // false from the do_bit() method. However, inside the 4294 // do_bit() method we move the _finger to point to the 4295 // object currently being looked at. So, if we bail out, we 4296 // have definitely set _finger to something non-null. 4297 assert(_finger != NULL, "invariant"); 4298 4299 // Region iteration was actually aborted. So now _finger 4300 // points to the address of the object we last scanned. If we 4301 // leave it there, when we restart this task, we will rescan 4302 // the object. It is easy to avoid this. We move the finger by 4303 // enough to point to the next possible object header (the 4304 // bitmap knows by how much we need to move it as it knows its 4305 // granularity). 4306 assert(_finger < _region_limit, "invariant"); 4307 HeapWord* new_finger = _nextMarkBitMap->nextObject(_finger); 4308 // Check if bitmap iteration was aborted while scanning the last object 4309 if (new_finger >= _region_limit) { 4310 giveup_current_region(); 4311 } else { 4312 move_finger_to(new_finger); 4313 } 4314 } 4315 } 4316 // At this point we have either completed iterating over the 4317 // region we were holding on to, or we have aborted. 4318 4319 // We then partially drain the local queue and the global stack. 4320 // (Do we really need this?) 4321 drain_local_queue(true); 4322 drain_global_stack(true); 4323 4324 // Read the note on the claim_region() method on why it might 4325 // return NULL with potentially more regions available for 4326 // claiming and why we have to check out_of_regions() to determine 4327 // whether we're done or not. 4328 while (!has_aborted() && _curr_region == NULL && !_cm->out_of_regions()) { 4329 // We are going to try to claim a new region. We should have 4330 // given up on the previous one. 4331 // Separated the asserts so that we know which one fires. 4332 assert(_curr_region == NULL, "invariant"); 4333 assert(_finger == NULL, "invariant"); 4334 assert(_region_limit == NULL, "invariant"); 4335 if (_cm->verbose_low()) { 4336 gclog_or_tty->print_cr("[%u] trying to claim a new region", _worker_id); 4337 } 4338 HeapRegion* claimed_region = _cm->claim_region(_worker_id); 4339 if (claimed_region != NULL) { 4340 // Yes, we managed to claim one 4341 statsOnly( ++_regions_claimed ); 4342 4343 if (_cm->verbose_low()) { 4344 gclog_or_tty->print_cr("[%u] we successfully claimed " 4345 "region "PTR_FORMAT, 4346 _worker_id, p2i(claimed_region)); 4347 } 4348 4349 setup_for_region(claimed_region); 4350 assert(_curr_region == claimed_region, "invariant"); 4351 } 4352 // It is important to call the regular clock here. It might take 4353 // a while to claim a region if, for example, we hit a large 4354 // block of empty regions. So we need to call the regular clock 4355 // method once round the loop to make sure it's called 4356 // frequently enough. 4357 regular_clock_call(); 4358 } 4359 4360 if (!has_aborted() && _curr_region == NULL) { 4361 assert(_cm->out_of_regions(), 4362 "at this point we should be out of regions"); 4363 } 4364 } while ( _curr_region != NULL && !has_aborted()); 4365 4366 if (!has_aborted()) { 4367 // We cannot check whether the global stack is empty, since other 4368 // tasks might be pushing objects to it concurrently. 4369 assert(_cm->out_of_regions(), 4370 "at this point we should be out of regions"); 4371 4372 if (_cm->verbose_low()) { 4373 gclog_or_tty->print_cr("[%u] all regions claimed", _worker_id); 4374 } 4375 4376 // Try to reduce the number of available SATB buffers so that 4377 // remark has less work to do. 4378 drain_satb_buffers(); 4379 } 4380 4381 // Since we've done everything else, we can now totally drain the 4382 // local queue and global stack. 4383 drain_local_queue(false); 4384 drain_global_stack(false); 4385 4386 // Attempt at work stealing from other task's queues. 4387 if (do_stealing && !has_aborted()) { 4388 // We have not aborted. This means that we have finished all that 4389 // we could. Let's try to do some stealing... 4390 4391 // We cannot check whether the global stack is empty, since other 4392 // tasks might be pushing objects to it concurrently. 4393 assert(_cm->out_of_regions() && _task_queue->size() == 0, 4394 "only way to reach here"); 4395 4396 if (_cm->verbose_low()) { 4397 gclog_or_tty->print_cr("[%u] starting to steal", _worker_id); 4398 } 4399 4400 while (!has_aborted()) { 4401 oop obj; 4402 statsOnly( ++_steal_attempts ); 4403 4404 if (_cm->try_stealing(_worker_id, &_hash_seed, obj)) { 4405 if (_cm->verbose_medium()) { 4406 gclog_or_tty->print_cr("[%u] stolen "PTR_FORMAT" successfully", 4407 _worker_id, p2i((void*) obj)); 4408 } 4409 4410 statsOnly( ++_steals ); 4411 4412 assert(_nextMarkBitMap->isMarked((HeapWord*) obj), 4413 "any stolen object should be marked"); 4414 scan_object(obj); 4415 4416 // And since we're towards the end, let's totally drain the 4417 // local queue and global stack. 4418 drain_local_queue(false); 4419 drain_global_stack(false); 4420 } else { 4421 break; 4422 } 4423 } 4424 } 4425 4426 // If we are about to wrap up and go into termination, check if we 4427 // should raise the overflow flag. 4428 if (do_termination && !has_aborted()) { 4429 if (_cm->force_overflow()->should_force()) { 4430 _cm->set_has_overflown(); 4431 regular_clock_call(); 4432 } 4433 } 4434 4435 // We still haven't aborted. Now, let's try to get into the 4436 // termination protocol. 4437 if (do_termination && !has_aborted()) { 4438 // We cannot check whether the global stack is empty, since other 4439 // tasks might be concurrently pushing objects on it. 4440 // Separated the asserts so that we know which one fires. 4441 assert(_cm->out_of_regions(), "only way to reach here"); 4442 assert(_task_queue->size() == 0, "only way to reach here"); 4443 4444 if (_cm->verbose_low()) { 4445 gclog_or_tty->print_cr("[%u] starting termination protocol", _worker_id); 4446 } 4447 4448 _termination_start_time_ms = os::elapsedVTime() * 1000.0; 4449 4450 // The CMTask class also extends the TerminatorTerminator class, 4451 // hence its should_exit_termination() method will also decide 4452 // whether to exit the termination protocol or not. 4453 bool finished = (is_serial || 4454 _cm->terminator()->offer_termination(this)); 4455 double termination_end_time_ms = os::elapsedVTime() * 1000.0; 4456 _termination_time_ms += 4457 termination_end_time_ms - _termination_start_time_ms; 4458 4459 if (finished) { 4460 // We're all done. 4461 4462 if (_worker_id == 0) { 4463 // let's allow task 0 to do this 4464 if (concurrent()) { 4465 assert(_cm->concurrent_marking_in_progress(), "invariant"); 4466 // we need to set this to false before the next 4467 // safepoint. This way we ensure that the marking phase 4468 // doesn't observe any more heap expansions. 4469 _cm->clear_concurrent_marking_in_progress(); 4470 } 4471 } 4472 4473 // We can now guarantee that the global stack is empty, since 4474 // all other tasks have finished. We separated the guarantees so 4475 // that, if a condition is false, we can immediately find out 4476 // which one. 4477 guarantee(_cm->out_of_regions(), "only way to reach here"); 4478 guarantee(_cm->mark_stack_empty(), "only way to reach here"); 4479 guarantee(_task_queue->size() == 0, "only way to reach here"); 4480 guarantee(!_cm->has_overflown(), "only way to reach here"); 4481 guarantee(!_cm->mark_stack_overflow(), "only way to reach here"); 4482 4483 if (_cm->verbose_low()) { 4484 gclog_or_tty->print_cr("[%u] all tasks terminated", _worker_id); 4485 } 4486 } else { 4487 // Apparently there's more work to do. Let's abort this task. It 4488 // will restart it and we can hopefully find more things to do. 4489 4490 if (_cm->verbose_low()) { 4491 gclog_or_tty->print_cr("[%u] apparently there is more work to do", 4492 _worker_id); 4493 } 4494 4495 set_has_aborted(); 4496 statsOnly( ++_aborted_termination ); 4497 } 4498 } 4499 4500 // Mainly for debugging purposes to make sure that a pointer to the 4501 // closure which was statically allocated in this frame doesn't 4502 // escape it by accident. 4503 set_cm_oop_closure(NULL); 4504 double end_time_ms = os::elapsedVTime() * 1000.0; 4505 double elapsed_time_ms = end_time_ms - _start_time_ms; 4506 // Update the step history. 4507 _step_times_ms.add(elapsed_time_ms); 4508 4509 if (has_aborted()) { 4510 // The task was aborted for some reason. 4511 4512 statsOnly( ++_aborted ); 4513 4514 if (_has_timed_out) { 4515 double diff_ms = elapsed_time_ms - _time_target_ms; 4516 // Keep statistics of how well we did with respect to hitting 4517 // our target only if we actually timed out (if we aborted for 4518 // other reasons, then the results might get skewed). 4519 _marking_step_diffs_ms.add(diff_ms); 4520 } 4521 4522 if (_cm->has_overflown()) { 4523 // This is the interesting one. We aborted because a global 4524 // overflow was raised. This means we have to restart the 4525 // marking phase and start iterating over regions. However, in 4526 // order to do this we have to make sure that all tasks stop 4527 // what they are doing and re-initialise in a safe manner. We 4528 // will achieve this with the use of two barrier sync points. 4529 4530 if (_cm->verbose_low()) { 4531 gclog_or_tty->print_cr("[%u] detected overflow", _worker_id); 4532 } 4533 4534 if (!is_serial) { 4535 // We only need to enter the sync barrier if being called 4536 // from a parallel context 4537 _cm->enter_first_sync_barrier(_worker_id); 4538 4539 // When we exit this sync barrier we know that all tasks have 4540 // stopped doing marking work. So, it's now safe to 4541 // re-initialise our data structures. At the end of this method, 4542 // task 0 will clear the global data structures. 4543 } 4544 4545 statsOnly( ++_aborted_overflow ); 4546 4547 // We clear the local state of this task... 4548 clear_region_fields(); 4549 4550 if (!is_serial) { 4551 // ...and enter the second barrier. 4552 _cm->enter_second_sync_barrier(_worker_id); 4553 } 4554 // At this point, if we're during the concurrent phase of 4555 // marking, everything has been re-initialized and we're 4556 // ready to restart. 4557 } 4558 4559 if (_cm->verbose_low()) { 4560 gclog_or_tty->print_cr("[%u] <<<<<<<<<< ABORTING, target = %1.2lfms, " 4561 "elapsed = %1.2lfms <<<<<<<<<<", 4562 _worker_id, _time_target_ms, elapsed_time_ms); 4563 if (_cm->has_aborted()) { 4564 gclog_or_tty->print_cr("[%u] ========== MARKING ABORTED ==========", 4565 _worker_id); 4566 } 4567 } 4568 } else { 4569 if (_cm->verbose_low()) { 4570 gclog_or_tty->print_cr("[%u] <<<<<<<<<< FINISHED, target = %1.2lfms, " 4571 "elapsed = %1.2lfms <<<<<<<<<<", 4572 _worker_id, _time_target_ms, elapsed_time_ms); 4573 } 4574 } 4575 4576 _claimed = false; 4577 } 4578 4579 CMTask::CMTask(uint worker_id, 4580 ConcurrentMark* cm, 4581 size_t* marked_bytes, 4582 BitMap* card_bm, 4583 CMTaskQueue* task_queue, 4584 CMTaskQueueSet* task_queues) 4585 : _g1h(G1CollectedHeap::heap()), 4586 _worker_id(worker_id), _cm(cm), 4587 _claimed(false), 4588 _nextMarkBitMap(NULL), _hash_seed(17), 4589 _task_queue(task_queue), 4590 _task_queues(task_queues), 4591 _cm_oop_closure(NULL), 4592 _marked_bytes_array(marked_bytes), 4593 _card_bm(card_bm) { 4594 guarantee(task_queue != NULL, "invariant"); 4595 guarantee(task_queues != NULL, "invariant"); 4596 4597 statsOnly( _clock_due_to_scanning = 0; 4598 _clock_due_to_marking = 0 ); 4599 4600 _marking_step_diffs_ms.add(0.5); 4601 } 4602 4603 // These are formatting macros that are used below to ensure 4604 // consistent formatting. The *_H_* versions are used to format the 4605 // header for a particular value and they should be kept consistent 4606 // with the corresponding macro. Also note that most of the macros add 4607 // the necessary white space (as a prefix) which makes them a bit 4608 // easier to compose. 4609 4610 // All the output lines are prefixed with this string to be able to 4611 // identify them easily in a large log file. 4612 #define G1PPRL_LINE_PREFIX "###" 4613 4614 #define G1PPRL_ADDR_BASE_FORMAT " "PTR_FORMAT"-"PTR_FORMAT 4615 #ifdef _LP64 4616 #define G1PPRL_ADDR_BASE_H_FORMAT " %37s" 4617 #else // _LP64 4618 #define G1PPRL_ADDR_BASE_H_FORMAT " %21s" 4619 #endif // _LP64 4620 4621 // For per-region info 4622 #define G1PPRL_TYPE_FORMAT " %-4s" 4623 #define G1PPRL_TYPE_H_FORMAT " %4s" 4624 #define G1PPRL_BYTE_FORMAT " "SIZE_FORMAT_W(9) 4625 #define G1PPRL_BYTE_H_FORMAT " %9s" 4626 #define G1PPRL_DOUBLE_FORMAT " %14.1f" 4627 #define G1PPRL_DOUBLE_H_FORMAT " %14s" 4628 4629 // For summary info 4630 #define G1PPRL_SUM_ADDR_FORMAT(tag) " "tag":"G1PPRL_ADDR_BASE_FORMAT 4631 #define G1PPRL_SUM_BYTE_FORMAT(tag) " "tag": "SIZE_FORMAT 4632 #define G1PPRL_SUM_MB_FORMAT(tag) " "tag": %1.2f MB" 4633 #define G1PPRL_SUM_MB_PERC_FORMAT(tag) G1PPRL_SUM_MB_FORMAT(tag)" / %1.2f %%" 4634 4635 G1PrintRegionLivenessInfoClosure:: 4636 G1PrintRegionLivenessInfoClosure(outputStream* out, const char* phase_name) 4637 : _out(out), 4638 _total_used_bytes(0), _total_capacity_bytes(0), 4639 _total_prev_live_bytes(0), _total_next_live_bytes(0), 4640 _hum_used_bytes(0), _hum_capacity_bytes(0), 4641 _hum_prev_live_bytes(0), _hum_next_live_bytes(0), 4642 _total_remset_bytes(0), _total_strong_code_roots_bytes(0) { 4643 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4644 MemRegion g1_reserved = g1h->g1_reserved(); 4645 double now = os::elapsedTime(); 4646 4647 // Print the header of the output. 4648 _out->cr(); 4649 _out->print_cr(G1PPRL_LINE_PREFIX" PHASE %s @ %1.3f", phase_name, now); 4650 _out->print_cr(G1PPRL_LINE_PREFIX" HEAP" 4651 G1PPRL_SUM_ADDR_FORMAT("reserved") 4652 G1PPRL_SUM_BYTE_FORMAT("region-size"), 4653 p2i(g1_reserved.start()), p2i(g1_reserved.end()), 4654 HeapRegion::GrainBytes); 4655 _out->print_cr(G1PPRL_LINE_PREFIX); 4656 _out->print_cr(G1PPRL_LINE_PREFIX 4657 G1PPRL_TYPE_H_FORMAT 4658 G1PPRL_ADDR_BASE_H_FORMAT 4659 G1PPRL_BYTE_H_FORMAT 4660 G1PPRL_BYTE_H_FORMAT 4661 G1PPRL_BYTE_H_FORMAT 4662 G1PPRL_DOUBLE_H_FORMAT 4663 G1PPRL_BYTE_H_FORMAT 4664 G1PPRL_BYTE_H_FORMAT, 4665 "type", "address-range", 4666 "used", "prev-live", "next-live", "gc-eff", 4667 "remset", "code-roots"); 4668 _out->print_cr(G1PPRL_LINE_PREFIX 4669 G1PPRL_TYPE_H_FORMAT 4670 G1PPRL_ADDR_BASE_H_FORMAT 4671 G1PPRL_BYTE_H_FORMAT 4672 G1PPRL_BYTE_H_FORMAT 4673 G1PPRL_BYTE_H_FORMAT 4674 G1PPRL_DOUBLE_H_FORMAT 4675 G1PPRL_BYTE_H_FORMAT 4676 G1PPRL_BYTE_H_FORMAT, 4677 "", "", 4678 "(bytes)", "(bytes)", "(bytes)", "(bytes/ms)", 4679 "(bytes)", "(bytes)"); 4680 } 4681 4682 // It takes as a parameter a reference to one of the _hum_* fields, it 4683 // deduces the corresponding value for a region in a humongous region 4684 // series (either the region size, or what's left if the _hum_* field 4685 // is < the region size), and updates the _hum_* field accordingly. 4686 size_t G1PrintRegionLivenessInfoClosure::get_hum_bytes(size_t* hum_bytes) { 4687 size_t bytes = 0; 4688 // The > 0 check is to deal with the prev and next live bytes which 4689 // could be 0. 4690 if (*hum_bytes > 0) { 4691 bytes = MIN2(HeapRegion::GrainBytes, *hum_bytes); 4692 *hum_bytes -= bytes; 4693 } 4694 return bytes; 4695 } 4696 4697 // It deduces the values for a region in a humongous region series 4698 // from the _hum_* fields and updates those accordingly. It assumes 4699 // that that _hum_* fields have already been set up from the "starts 4700 // humongous" region and we visit the regions in address order. 4701 void G1PrintRegionLivenessInfoClosure::get_hum_bytes(size_t* used_bytes, 4702 size_t* capacity_bytes, 4703 size_t* prev_live_bytes, 4704 size_t* next_live_bytes) { 4705 assert(_hum_used_bytes > 0 && _hum_capacity_bytes > 0, "pre-condition"); 4706 *used_bytes = get_hum_bytes(&_hum_used_bytes); 4707 *capacity_bytes = get_hum_bytes(&_hum_capacity_bytes); 4708 *prev_live_bytes = get_hum_bytes(&_hum_prev_live_bytes); 4709 *next_live_bytes = get_hum_bytes(&_hum_next_live_bytes); 4710 } 4711 4712 bool G1PrintRegionLivenessInfoClosure::doHeapRegion(HeapRegion* r) { 4713 const char* type = r->get_type_str(); 4714 HeapWord* bottom = r->bottom(); 4715 HeapWord* end = r->end(); 4716 size_t capacity_bytes = r->capacity(); 4717 size_t used_bytes = r->used(); 4718 size_t prev_live_bytes = r->live_bytes(); 4719 size_t next_live_bytes = r->next_live_bytes(); 4720 double gc_eff = r->gc_efficiency(); 4721 size_t remset_bytes = r->rem_set()->mem_size(); 4722 size_t strong_code_roots_bytes = r->rem_set()->strong_code_roots_mem_size(); 4723 4724 if (r->startsHumongous()) { 4725 assert(_hum_used_bytes == 0 && _hum_capacity_bytes == 0 && 4726 _hum_prev_live_bytes == 0 && _hum_next_live_bytes == 0, 4727 "they should have been zeroed after the last time we used them"); 4728 // Set up the _hum_* fields. 4729 _hum_capacity_bytes = capacity_bytes; 4730 _hum_used_bytes = used_bytes; 4731 _hum_prev_live_bytes = prev_live_bytes; 4732 _hum_next_live_bytes = next_live_bytes; 4733 get_hum_bytes(&used_bytes, &capacity_bytes, 4734 &prev_live_bytes, &next_live_bytes); 4735 end = bottom + HeapRegion::GrainWords; 4736 } else if (r->continuesHumongous()) { 4737 get_hum_bytes(&used_bytes, &capacity_bytes, 4738 &prev_live_bytes, &next_live_bytes); 4739 assert(end == bottom + HeapRegion::GrainWords, "invariant"); 4740 } 4741 4742 _total_used_bytes += used_bytes; 4743 _total_capacity_bytes += capacity_bytes; 4744 _total_prev_live_bytes += prev_live_bytes; 4745 _total_next_live_bytes += next_live_bytes; 4746 _total_remset_bytes += remset_bytes; 4747 _total_strong_code_roots_bytes += strong_code_roots_bytes; 4748 4749 // Print a line for this particular region. 4750 _out->print_cr(G1PPRL_LINE_PREFIX 4751 G1PPRL_TYPE_FORMAT 4752 G1PPRL_ADDR_BASE_FORMAT 4753 G1PPRL_BYTE_FORMAT 4754 G1PPRL_BYTE_FORMAT 4755 G1PPRL_BYTE_FORMAT 4756 G1PPRL_DOUBLE_FORMAT 4757 G1PPRL_BYTE_FORMAT 4758 G1PPRL_BYTE_FORMAT, 4759 type, p2i(bottom), p2i(end), 4760 used_bytes, prev_live_bytes, next_live_bytes, gc_eff, 4761 remset_bytes, strong_code_roots_bytes); 4762 4763 return false; 4764 } 4765 4766 G1PrintRegionLivenessInfoClosure::~G1PrintRegionLivenessInfoClosure() { 4767 // add static memory usages to remembered set sizes 4768 _total_remset_bytes += HeapRegionRemSet::fl_mem_size() + HeapRegionRemSet::static_mem_size(); 4769 // Print the footer of the output. 4770 _out->print_cr(G1PPRL_LINE_PREFIX); 4771 _out->print_cr(G1PPRL_LINE_PREFIX 4772 " SUMMARY" 4773 G1PPRL_SUM_MB_FORMAT("capacity") 4774 G1PPRL_SUM_MB_PERC_FORMAT("used") 4775 G1PPRL_SUM_MB_PERC_FORMAT("prev-live") 4776 G1PPRL_SUM_MB_PERC_FORMAT("next-live") 4777 G1PPRL_SUM_MB_FORMAT("remset") 4778 G1PPRL_SUM_MB_FORMAT("code-roots"), 4779 bytes_to_mb(_total_capacity_bytes), 4780 bytes_to_mb(_total_used_bytes), 4781 perc(_total_used_bytes, _total_capacity_bytes), 4782 bytes_to_mb(_total_prev_live_bytes), 4783 perc(_total_prev_live_bytes, _total_capacity_bytes), 4784 bytes_to_mb(_total_next_live_bytes), 4785 perc(_total_next_live_bytes, _total_capacity_bytes), 4786 bytes_to_mb(_total_remset_bytes), 4787 bytes_to_mb(_total_strong_code_roots_bytes)); 4788 _out->cr(); 4789 }