1 /* 2 * Copyright (c) 2001, 2019, 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/classLoaderDataGraph.hpp" 27 #include "code/codeCache.hpp" 28 #include "gc/g1/g1BarrierSet.hpp" 29 #include "gc/g1/g1CollectedHeap.inline.hpp" 30 #include "gc/g1/g1CollectorState.hpp" 31 #include "gc/g1/g1ConcurrentMark.inline.hpp" 32 #include "gc/g1/g1ConcurrentMarkThread.inline.hpp" 33 #include "gc/g1/g1DirtyCardQueue.hpp" 34 #include "gc/g1/g1HeapVerifier.hpp" 35 #include "gc/g1/g1OopClosures.inline.hpp" 36 #include "gc/g1/g1Policy.hpp" 37 #include "gc/g1/g1RegionMarkStatsCache.inline.hpp" 38 #include "gc/g1/g1StringDedup.hpp" 39 #include "gc/g1/g1ThreadLocalData.hpp" 40 #include "gc/g1/heapRegion.inline.hpp" 41 #include "gc/g1/heapRegionRemSet.hpp" 42 #include "gc/g1/heapRegionSet.inline.hpp" 43 #include "gc/shared/gcId.hpp" 44 #include "gc/shared/gcTimer.hpp" 45 #include "gc/shared/gcTrace.hpp" 46 #include "gc/shared/gcTraceTime.inline.hpp" 47 #include "gc/shared/gcVMOperations.hpp" 48 #include "gc/shared/genOopClosures.inline.hpp" 49 #include "gc/shared/referencePolicy.hpp" 50 #include "gc/shared/strongRootsScope.hpp" 51 #include "gc/shared/suspendibleThreadSet.hpp" 52 #include "gc/shared/taskqueue.inline.hpp" 53 #include "gc/shared/weakProcessor.inline.hpp" 54 #include "gc/shared/workerPolicy.hpp" 55 #include "include/jvm.h" 56 #include "logging/log.hpp" 57 #include "memory/allocation.hpp" 58 #include "memory/resourceArea.hpp" 59 #include "oops/access.inline.hpp" 60 #include "oops/oop.inline.hpp" 61 #include "runtime/atomic.hpp" 62 #include "runtime/handles.inline.hpp" 63 #include "runtime/java.hpp" 64 #include "runtime/prefetch.inline.hpp" 65 #include "services/memTracker.hpp" 66 #include "utilities/align.hpp" 67 #include "utilities/growableArray.hpp" 68 69 bool G1CMBitMapClosure::do_addr(HeapWord* const addr) { 70 assert(addr < _cm->finger(), "invariant"); 71 assert(addr >= _task->finger(), "invariant"); 72 73 // We move that task's local finger along. 74 _task->move_finger_to(addr); 75 76 _task->scan_task_entry(G1TaskQueueEntry::from_oop(oop(addr))); 77 // we only partially drain the local queue and global stack 78 _task->drain_local_queue(true); 79 _task->drain_global_stack(true); 80 81 // if the has_aborted flag has been raised, we need to bail out of 82 // the iteration 83 return !_task->has_aborted(); 84 } 85 86 G1CMMarkStack::G1CMMarkStack() : 87 _max_chunk_capacity(0), 88 _base(NULL), 89 _chunk_capacity(0) { 90 set_empty(); 91 } 92 93 bool G1CMMarkStack::resize(size_t new_capacity) { 94 assert(is_empty(), "Only resize when stack is empty."); 95 assert(new_capacity <= _max_chunk_capacity, 96 "Trying to resize stack to " SIZE_FORMAT " chunks when the maximum is " SIZE_FORMAT, new_capacity, _max_chunk_capacity); 97 98 TaskQueueEntryChunk* new_base = MmapArrayAllocator<TaskQueueEntryChunk>::allocate_or_null(new_capacity, mtGC); 99 100 if (new_base == NULL) { 101 log_warning(gc)("Failed to reserve memory for new overflow mark stack with " SIZE_FORMAT " chunks and size " SIZE_FORMAT "B.", new_capacity, new_capacity * sizeof(TaskQueueEntryChunk)); 102 return false; 103 } 104 // Release old mapping. 105 if (_base != NULL) { 106 MmapArrayAllocator<TaskQueueEntryChunk>::free(_base, _chunk_capacity); 107 } 108 109 _base = new_base; 110 _chunk_capacity = new_capacity; 111 set_empty(); 112 113 return true; 114 } 115 116 size_t G1CMMarkStack::capacity_alignment() { 117 return (size_t)lcm(os::vm_allocation_granularity(), sizeof(TaskQueueEntryChunk)) / sizeof(G1TaskQueueEntry); 118 } 119 120 bool G1CMMarkStack::initialize(size_t initial_capacity, size_t max_capacity) { 121 guarantee(_max_chunk_capacity == 0, "G1CMMarkStack already initialized."); 122 123 size_t const TaskEntryChunkSizeInVoidStar = sizeof(TaskQueueEntryChunk) / sizeof(G1TaskQueueEntry); 124 125 _max_chunk_capacity = align_up(max_capacity, capacity_alignment()) / TaskEntryChunkSizeInVoidStar; 126 size_t initial_chunk_capacity = align_up(initial_capacity, capacity_alignment()) / TaskEntryChunkSizeInVoidStar; 127 128 guarantee(initial_chunk_capacity <= _max_chunk_capacity, 129 "Maximum chunk capacity " SIZE_FORMAT " smaller than initial capacity " SIZE_FORMAT, 130 _max_chunk_capacity, 131 initial_chunk_capacity); 132 133 log_debug(gc)("Initialize mark stack with " SIZE_FORMAT " chunks, maximum " SIZE_FORMAT, 134 initial_chunk_capacity, _max_chunk_capacity); 135 136 return resize(initial_chunk_capacity); 137 } 138 139 void G1CMMarkStack::expand() { 140 if (_chunk_capacity == _max_chunk_capacity) { 141 log_debug(gc)("Can not expand overflow mark stack further, already at maximum capacity of " SIZE_FORMAT " chunks.", _chunk_capacity); 142 return; 143 } 144 size_t old_capacity = _chunk_capacity; 145 // Double capacity if possible 146 size_t new_capacity = MIN2(old_capacity * 2, _max_chunk_capacity); 147 148 if (resize(new_capacity)) { 149 log_debug(gc)("Expanded mark stack capacity from " SIZE_FORMAT " to " SIZE_FORMAT " chunks", 150 old_capacity, new_capacity); 151 } else { 152 log_warning(gc)("Failed to expand mark stack capacity from " SIZE_FORMAT " to " SIZE_FORMAT " chunks", 153 old_capacity, new_capacity); 154 } 155 } 156 157 G1CMMarkStack::~G1CMMarkStack() { 158 if (_base != NULL) { 159 MmapArrayAllocator<TaskQueueEntryChunk>::free(_base, _chunk_capacity); 160 } 161 } 162 163 void G1CMMarkStack::add_chunk_to_list(TaskQueueEntryChunk* volatile* list, TaskQueueEntryChunk* elem) { 164 elem->next = *list; 165 *list = elem; 166 } 167 168 void G1CMMarkStack::add_chunk_to_chunk_list(TaskQueueEntryChunk* elem) { 169 MutexLockerEx x(MarkStackChunkList_lock, Mutex::_no_safepoint_check_flag); 170 add_chunk_to_list(&_chunk_list, elem); 171 _chunks_in_chunk_list++; 172 } 173 174 void G1CMMarkStack::add_chunk_to_free_list(TaskQueueEntryChunk* elem) { 175 MutexLockerEx x(MarkStackFreeList_lock, Mutex::_no_safepoint_check_flag); 176 add_chunk_to_list(&_free_list, elem); 177 } 178 179 G1CMMarkStack::TaskQueueEntryChunk* G1CMMarkStack::remove_chunk_from_list(TaskQueueEntryChunk* volatile* list) { 180 TaskQueueEntryChunk* result = *list; 181 if (result != NULL) { 182 *list = (*list)->next; 183 } 184 return result; 185 } 186 187 G1CMMarkStack::TaskQueueEntryChunk* G1CMMarkStack::remove_chunk_from_chunk_list() { 188 MutexLockerEx x(MarkStackChunkList_lock, Mutex::_no_safepoint_check_flag); 189 TaskQueueEntryChunk* result = remove_chunk_from_list(&_chunk_list); 190 if (result != NULL) { 191 _chunks_in_chunk_list--; 192 } 193 return result; 194 } 195 196 G1CMMarkStack::TaskQueueEntryChunk* G1CMMarkStack::remove_chunk_from_free_list() { 197 MutexLockerEx x(MarkStackFreeList_lock, Mutex::_no_safepoint_check_flag); 198 return remove_chunk_from_list(&_free_list); 199 } 200 201 G1CMMarkStack::TaskQueueEntryChunk* G1CMMarkStack::allocate_new_chunk() { 202 // This dirty read of _hwm is okay because we only ever increase the _hwm in parallel code. 203 // Further this limits _hwm to a value of _chunk_capacity + #threads, avoiding 204 // wraparound of _hwm. 205 if (_hwm >= _chunk_capacity) { 206 return NULL; 207 } 208 209 size_t cur_idx = Atomic::add(1u, &_hwm) - 1; 210 if (cur_idx >= _chunk_capacity) { 211 return NULL; 212 } 213 214 TaskQueueEntryChunk* result = ::new (&_base[cur_idx]) TaskQueueEntryChunk; 215 result->next = NULL; 216 return result; 217 } 218 219 bool G1CMMarkStack::par_push_chunk(G1TaskQueueEntry* ptr_arr) { 220 // Get a new chunk. 221 TaskQueueEntryChunk* new_chunk = remove_chunk_from_free_list(); 222 223 if (new_chunk == NULL) { 224 // Did not get a chunk from the free list. Allocate from backing memory. 225 new_chunk = allocate_new_chunk(); 226 227 if (new_chunk == NULL) { 228 return false; 229 } 230 } 231 232 Copy::conjoint_memory_atomic(ptr_arr, new_chunk->data, EntriesPerChunk * sizeof(G1TaskQueueEntry)); 233 234 add_chunk_to_chunk_list(new_chunk); 235 236 return true; 237 } 238 239 bool G1CMMarkStack::par_pop_chunk(G1TaskQueueEntry* ptr_arr) { 240 TaskQueueEntryChunk* cur = remove_chunk_from_chunk_list(); 241 242 if (cur == NULL) { 243 return false; 244 } 245 246 Copy::conjoint_memory_atomic(cur->data, ptr_arr, EntriesPerChunk * sizeof(G1TaskQueueEntry)); 247 248 add_chunk_to_free_list(cur); 249 return true; 250 } 251 252 void G1CMMarkStack::set_empty() { 253 _chunks_in_chunk_list = 0; 254 _hwm = 0; 255 _chunk_list = NULL; 256 _free_list = NULL; 257 } 258 259 G1CMRootRegions::G1CMRootRegions(uint const max_regions) : 260 _root_regions(NEW_C_HEAP_ARRAY(HeapRegion*, max_regions, mtGC)), 261 _max_regions(max_regions), 262 _num_root_regions(0), 263 _claimed_root_regions(0), 264 _scan_in_progress(false), 265 _should_abort(false) { } 266 267 G1CMRootRegions::~G1CMRootRegions() { 268 FREE_C_HEAP_ARRAY(HeapRegion*, _max_regions); 269 } 270 271 void G1CMRootRegions::reset() { 272 _num_root_regions = 0; 273 } 274 275 void G1CMRootRegions::add(HeapRegion* hr) { 276 assert_at_safepoint(); 277 size_t idx = Atomic::add((size_t)1, &_num_root_regions) - 1; 278 assert(idx < _max_regions, "Trying to add more root regions than there is space " SIZE_FORMAT, _max_regions); 279 _root_regions[idx] = hr; 280 } 281 282 void G1CMRootRegions::prepare_for_scan() { 283 assert(!scan_in_progress(), "pre-condition"); 284 285 _scan_in_progress = _num_root_regions > 0; 286 287 _claimed_root_regions = 0; 288 _should_abort = false; 289 } 290 291 HeapRegion* G1CMRootRegions::claim_next() { 292 if (_should_abort) { 293 // If someone has set the should_abort flag, we return NULL to 294 // force the caller to bail out of their loop. 295 return NULL; 296 } 297 298 if (_claimed_root_regions >= _num_root_regions) { 299 return NULL; 300 } 301 302 size_t claimed_index = Atomic::add((size_t)1, &_claimed_root_regions) - 1; 303 if (claimed_index < _num_root_regions) { 304 return _root_regions[claimed_index]; 305 } 306 return NULL; 307 } 308 309 uint G1CMRootRegions::num_root_regions() const { 310 return (uint)_num_root_regions; 311 } 312 313 void G1CMRootRegions::notify_scan_done() { 314 MutexLockerEx x(RootRegionScan_lock, Mutex::_no_safepoint_check_flag); 315 _scan_in_progress = false; 316 RootRegionScan_lock->notify_all(); 317 } 318 319 void G1CMRootRegions::cancel_scan() { 320 notify_scan_done(); 321 } 322 323 void G1CMRootRegions::scan_finished() { 324 assert(scan_in_progress(), "pre-condition"); 325 326 if (!_should_abort) { 327 assert(_claimed_root_regions >= num_root_regions(), 328 "we should have claimed all root regions, claimed " SIZE_FORMAT ", length = %u", 329 _claimed_root_regions, num_root_regions()); 330 } 331 332 notify_scan_done(); 333 } 334 335 bool G1CMRootRegions::wait_until_scan_finished() { 336 if (!scan_in_progress()) { 337 return false; 338 } 339 340 { 341 MutexLockerEx x(RootRegionScan_lock, Mutex::_no_safepoint_check_flag); 342 while (scan_in_progress()) { 343 RootRegionScan_lock->wait(Mutex::_no_safepoint_check_flag); 344 } 345 } 346 return true; 347 } 348 349 // Returns the maximum number of workers to be used in a concurrent 350 // phase based on the number of GC workers being used in a STW 351 // phase. 352 static uint scale_concurrent_worker_threads(uint num_gc_workers) { 353 return MAX2((num_gc_workers + 2) / 4, 1U); 354 } 355 356 G1ConcurrentMark::G1ConcurrentMark(G1CollectedHeap* g1h, 357 G1RegionToSpaceMapper* prev_bitmap_storage, 358 G1RegionToSpaceMapper* next_bitmap_storage) : 359 // _cm_thread set inside the constructor 360 _g1h(g1h), 361 _completed_initialization(false), 362 363 _mark_bitmap_1(), 364 _mark_bitmap_2(), 365 _prev_mark_bitmap(&_mark_bitmap_1), 366 _next_mark_bitmap(&_mark_bitmap_2), 367 368 _heap(_g1h->reserved_region()), 369 370 _root_regions(_g1h->max_regions()), 371 372 _global_mark_stack(), 373 374 // _finger set in set_non_marking_state 375 376 _worker_id_offset(G1DirtyCardQueueSet::num_par_ids() + G1ConcRefinementThreads), 377 _max_num_tasks(ParallelGCThreads), 378 // _num_active_tasks set in set_non_marking_state() 379 // _tasks set inside the constructor 380 381 _task_queues(new G1CMTaskQueueSet((int) _max_num_tasks)), 382 _terminator((int) _max_num_tasks, _task_queues), 383 384 _first_overflow_barrier_sync(), 385 _second_overflow_barrier_sync(), 386 387 _has_overflown(false), 388 _concurrent(false), 389 _has_aborted(false), 390 _restart_for_overflow(false), 391 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()), 392 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()), 393 394 // _verbose_level set below 395 396 _init_times(), 397 _remark_times(), 398 _remark_mark_times(), 399 _remark_weak_ref_times(), 400 _cleanup_times(), 401 _total_cleanup_time(0.0), 402 403 _accum_task_vtime(NULL), 404 405 _concurrent_workers(NULL), 406 _num_concurrent_workers(0), 407 _max_concurrent_workers(0), 408 409 _region_mark_stats(NEW_C_HEAP_ARRAY(G1RegionMarkStats, _g1h->max_regions(), mtGC)), 410 _top_at_rebuild_starts(NEW_C_HEAP_ARRAY(HeapWord*, _g1h->max_regions(), mtGC)) 411 { 412 _mark_bitmap_1.initialize(g1h->reserved_region(), prev_bitmap_storage); 413 _mark_bitmap_2.initialize(g1h->reserved_region(), next_bitmap_storage); 414 415 // Create & start ConcurrentMark thread. 416 _cm_thread = new G1ConcurrentMarkThread(this); 417 if (_cm_thread->osthread() == NULL) { 418 vm_shutdown_during_initialization("Could not create ConcurrentMarkThread"); 419 } 420 421 assert(CGC_lock != NULL, "CGC_lock must be initialized"); 422 423 if (FLAG_IS_DEFAULT(ConcGCThreads) || ConcGCThreads == 0) { 424 // Calculate the number of concurrent worker threads by scaling 425 // the number of parallel GC threads. 426 uint marking_thread_num = scale_concurrent_worker_threads(ParallelGCThreads); 427 FLAG_SET_ERGO(uint, ConcGCThreads, marking_thread_num); 428 } 429 430 assert(ConcGCThreads > 0, "ConcGCThreads have been set."); 431 if (ConcGCThreads > ParallelGCThreads) { 432 log_warning(gc)("More ConcGCThreads (%u) than ParallelGCThreads (%u).", 433 ConcGCThreads, ParallelGCThreads); 434 return; 435 } 436 437 log_debug(gc)("ConcGCThreads: %u offset %u", ConcGCThreads, _worker_id_offset); 438 log_debug(gc)("ParallelGCThreads: %u", ParallelGCThreads); 439 440 _num_concurrent_workers = ConcGCThreads; 441 _max_concurrent_workers = _num_concurrent_workers; 442 443 _concurrent_workers = new WorkGang("G1 Conc", _max_concurrent_workers, false, true); 444 _concurrent_workers->initialize_workers(); 445 446 if (FLAG_IS_DEFAULT(MarkStackSize)) { 447 size_t mark_stack_size = 448 MIN2(MarkStackSizeMax, 449 MAX2(MarkStackSize, (size_t) (_max_concurrent_workers * TASKQUEUE_SIZE))); 450 // Verify that the calculated value for MarkStackSize is in range. 451 // It would be nice to use the private utility routine from Arguments. 452 if (!(mark_stack_size >= 1 && mark_stack_size <= MarkStackSizeMax)) { 453 log_warning(gc)("Invalid value calculated for MarkStackSize (" SIZE_FORMAT "): " 454 "must be between 1 and " SIZE_FORMAT, 455 mark_stack_size, MarkStackSizeMax); 456 return; 457 } 458 FLAG_SET_ERGO(size_t, MarkStackSize, mark_stack_size); 459 } else { 460 // Verify MarkStackSize is in range. 461 if (FLAG_IS_CMDLINE(MarkStackSize)) { 462 if (FLAG_IS_DEFAULT(MarkStackSizeMax)) { 463 if (!(MarkStackSize >= 1 && MarkStackSize <= MarkStackSizeMax)) { 464 log_warning(gc)("Invalid value specified for MarkStackSize (" SIZE_FORMAT "): " 465 "must be between 1 and " SIZE_FORMAT, 466 MarkStackSize, MarkStackSizeMax); 467 return; 468 } 469 } else if (FLAG_IS_CMDLINE(MarkStackSizeMax)) { 470 if (!(MarkStackSize >= 1 && MarkStackSize <= MarkStackSizeMax)) { 471 log_warning(gc)("Invalid value specified for MarkStackSize (" SIZE_FORMAT ")" 472 " or for MarkStackSizeMax (" SIZE_FORMAT ")", 473 MarkStackSize, MarkStackSizeMax); 474 return; 475 } 476 } 477 } 478 } 479 480 if (!_global_mark_stack.initialize(MarkStackSize, MarkStackSizeMax)) { 481 vm_exit_during_initialization("Failed to allocate initial concurrent mark overflow mark stack."); 482 } 483 484 _tasks = NEW_C_HEAP_ARRAY(G1CMTask*, _max_num_tasks, mtGC); 485 _accum_task_vtime = NEW_C_HEAP_ARRAY(double, _max_num_tasks, mtGC); 486 487 // so that the assertion in MarkingTaskQueue::task_queue doesn't fail 488 _num_active_tasks = _max_num_tasks; 489 490 for (uint i = 0; i < _max_num_tasks; ++i) { 491 G1CMTaskQueue* task_queue = new G1CMTaskQueue(); 492 task_queue->initialize(); 493 _task_queues->register_queue(i, task_queue); 494 495 _tasks[i] = new G1CMTask(i, this, task_queue, _region_mark_stats, _g1h->max_regions()); 496 497 _accum_task_vtime[i] = 0.0; 498 } 499 500 reset_at_marking_complete(); 501 _completed_initialization = true; 502 } 503 504 void G1ConcurrentMark::reset() { 505 _has_aborted = false; 506 507 reset_marking_for_restart(); 508 509 // Reset all tasks, since different phases will use different number of active 510 // threads. So, it's easiest to have all of them ready. 511 for (uint i = 0; i < _max_num_tasks; ++i) { 512 _tasks[i]->reset(_next_mark_bitmap); 513 } 514 515 uint max_regions = _g1h->max_regions(); 516 for (uint i = 0; i < max_regions; i++) { 517 _top_at_rebuild_starts[i] = NULL; 518 _region_mark_stats[i].clear(); 519 } 520 } 521 522 void G1ConcurrentMark::clear_statistics_in_region(uint region_idx) { 523 for (uint j = 0; j < _max_num_tasks; ++j) { 524 _tasks[j]->clear_mark_stats_cache(region_idx); 525 } 526 _top_at_rebuild_starts[region_idx] = NULL; 527 _region_mark_stats[region_idx].clear(); 528 } 529 530 void G1ConcurrentMark::clear_statistics(HeapRegion* r) { 531 uint const region_idx = r->hrm_index(); 532 if (r->is_humongous()) { 533 assert(r->is_starts_humongous(), "Got humongous continues region here"); 534 uint const size_in_regions = (uint)_g1h->humongous_obj_size_in_regions(oop(r->humongous_start_region()->bottom())->size()); 535 for (uint j = region_idx; j < (region_idx + size_in_regions); j++) { 536 clear_statistics_in_region(j); 537 } 538 } else { 539 clear_statistics_in_region(region_idx); 540 } 541 } 542 543 static void clear_mark_if_set(G1CMBitMap* bitmap, HeapWord* addr) { 544 if (bitmap->is_marked(addr)) { 545 bitmap->clear(addr); 546 } 547 } 548 549 void G1ConcurrentMark::humongous_object_eagerly_reclaimed(HeapRegion* r) { 550 assert_at_safepoint_on_vm_thread(); 551 552 // Need to clear all mark bits of the humongous object. 553 clear_mark_if_set(_prev_mark_bitmap, r->bottom()); 554 clear_mark_if_set(_next_mark_bitmap, r->bottom()); 555 556 if (!_g1h->collector_state()->mark_or_rebuild_in_progress()) { 557 return; 558 } 559 560 // Clear any statistics about the region gathered so far. 561 clear_statistics(r); 562 } 563 564 void G1ConcurrentMark::reset_marking_for_restart() { 565 _global_mark_stack.set_empty(); 566 567 // Expand the marking stack, if we have to and if we can. 568 if (has_overflown()) { 569 _global_mark_stack.expand(); 570 571 uint max_regions = _g1h->max_regions(); 572 for (uint i = 0; i < max_regions; i++) { 573 _region_mark_stats[i].clear_during_overflow(); 574 } 575 } 576 577 clear_has_overflown(); 578 _finger = _heap.start(); 579 580 for (uint i = 0; i < _max_num_tasks; ++i) { 581 G1CMTaskQueue* queue = _task_queues->queue(i); 582 queue->set_empty(); 583 } 584 } 585 586 void G1ConcurrentMark::set_concurrency(uint active_tasks) { 587 assert(active_tasks <= _max_num_tasks, "we should not have more"); 588 589 _num_active_tasks = active_tasks; 590 // Need to update the three data structures below according to the 591 // number of active threads for this phase. 592 _terminator.terminator()->reset_for_reuse((int) active_tasks); 593 _first_overflow_barrier_sync.set_n_workers((int) active_tasks); 594 _second_overflow_barrier_sync.set_n_workers((int) active_tasks); 595 } 596 597 void G1ConcurrentMark::set_concurrency_and_phase(uint active_tasks, bool concurrent) { 598 set_concurrency(active_tasks); 599 600 _concurrent = concurrent; 601 602 if (!concurrent) { 603 // At this point we should be in a STW phase, and completed marking. 604 assert_at_safepoint_on_vm_thread(); 605 assert(out_of_regions(), 606 "only way to get here: _finger: " PTR_FORMAT ", _heap_end: " PTR_FORMAT, 607 p2i(_finger), p2i(_heap.end())); 608 } 609 } 610 611 void G1ConcurrentMark::reset_at_marking_complete() { 612 // We set the global marking state to some default values when we're 613 // not doing marking. 614 reset_marking_for_restart(); 615 _num_active_tasks = 0; 616 } 617 618 G1ConcurrentMark::~G1ConcurrentMark() { 619 FREE_C_HEAP_ARRAY(HeapWord*, _top_at_rebuild_starts); 620 FREE_C_HEAP_ARRAY(G1RegionMarkStats, _region_mark_stats); 621 // The G1ConcurrentMark instance is never freed. 622 ShouldNotReachHere(); 623 } 624 625 class G1ClearBitMapTask : public AbstractGangTask { 626 public: 627 static size_t chunk_size() { return M; } 628 629 private: 630 // Heap region closure used for clearing the given mark bitmap. 631 class G1ClearBitmapHRClosure : public HeapRegionClosure { 632 private: 633 G1CMBitMap* _bitmap; 634 G1ConcurrentMark* _cm; 635 public: 636 G1ClearBitmapHRClosure(G1CMBitMap* bitmap, G1ConcurrentMark* cm) : HeapRegionClosure(), _bitmap(bitmap), _cm(cm) { 637 } 638 639 virtual bool do_heap_region(HeapRegion* r) { 640 size_t const chunk_size_in_words = G1ClearBitMapTask::chunk_size() / HeapWordSize; 641 642 HeapWord* cur = r->bottom(); 643 HeapWord* const end = r->end(); 644 645 while (cur < end) { 646 MemRegion mr(cur, MIN2(cur + chunk_size_in_words, end)); 647 _bitmap->clear_range(mr); 648 649 cur += chunk_size_in_words; 650 651 // Abort iteration if after yielding the marking has been aborted. 652 if (_cm != NULL && _cm->do_yield_check() && _cm->has_aborted()) { 653 return true; 654 } 655 // Repeat the asserts from before the start of the closure. We will do them 656 // as asserts here to minimize their overhead on the product. However, we 657 // will have them as guarantees at the beginning / end of the bitmap 658 // clearing to get some checking in the product. 659 assert(_cm == NULL || _cm->cm_thread()->during_cycle(), "invariant"); 660 assert(_cm == NULL || !G1CollectedHeap::heap()->collector_state()->mark_or_rebuild_in_progress(), "invariant"); 661 } 662 assert(cur == end, "Must have completed iteration over the bitmap for region %u.", r->hrm_index()); 663 664 return false; 665 } 666 }; 667 668 G1ClearBitmapHRClosure _cl; 669 HeapRegionClaimer _hr_claimer; 670 bool _suspendible; // If the task is suspendible, workers must join the STS. 671 672 public: 673 G1ClearBitMapTask(G1CMBitMap* bitmap, G1ConcurrentMark* cm, uint n_workers, bool suspendible) : 674 AbstractGangTask("G1 Clear Bitmap"), 675 _cl(bitmap, suspendible ? cm : NULL), 676 _hr_claimer(n_workers), 677 _suspendible(suspendible) 678 { } 679 680 void work(uint worker_id) { 681 SuspendibleThreadSetJoiner sts_join(_suspendible); 682 G1CollectedHeap::heap()->heap_region_par_iterate_from_worker_offset(&_cl, &_hr_claimer, worker_id); 683 } 684 685 bool is_complete() { 686 return _cl.is_complete(); 687 } 688 }; 689 690 void G1ConcurrentMark::clear_bitmap(G1CMBitMap* bitmap, WorkGang* workers, bool may_yield) { 691 assert(may_yield || SafepointSynchronize::is_at_safepoint(), "Non-yielding bitmap clear only allowed at safepoint."); 692 693 size_t const num_bytes_to_clear = (HeapRegion::GrainBytes * _g1h->num_regions()) / G1CMBitMap::heap_map_factor(); 694 size_t const num_chunks = align_up(num_bytes_to_clear, G1ClearBitMapTask::chunk_size()) / G1ClearBitMapTask::chunk_size(); 695 696 uint const num_workers = (uint)MIN2(num_chunks, (size_t)workers->active_workers()); 697 698 G1ClearBitMapTask cl(bitmap, this, num_workers, may_yield); 699 700 log_debug(gc, ergo)("Running %s with %u workers for " SIZE_FORMAT " work units.", cl.name(), num_workers, num_chunks); 701 workers->run_task(&cl, num_workers); 702 guarantee(!may_yield || cl.is_complete(), "Must have completed iteration when not yielding."); 703 } 704 705 void G1ConcurrentMark::cleanup_for_next_mark() { 706 // Make sure that the concurrent mark thread looks to still be in 707 // the current cycle. 708 guarantee(cm_thread()->during_cycle(), "invariant"); 709 710 // We are finishing up the current cycle by clearing the next 711 // marking bitmap and getting it ready for the next cycle. During 712 // this time no other cycle can start. So, let's make sure that this 713 // is the case. 714 guarantee(!_g1h->collector_state()->mark_or_rebuild_in_progress(), "invariant"); 715 716 clear_bitmap(_next_mark_bitmap, _concurrent_workers, true); 717 718 // Repeat the asserts from above. 719 guarantee(cm_thread()->during_cycle(), "invariant"); 720 guarantee(!_g1h->collector_state()->mark_or_rebuild_in_progress(), "invariant"); 721 } 722 723 void G1ConcurrentMark::clear_prev_bitmap(WorkGang* workers) { 724 assert_at_safepoint_on_vm_thread(); 725 clear_bitmap(_prev_mark_bitmap, workers, false); 726 } 727 728 class NoteStartOfMarkHRClosure : public HeapRegionClosure { 729 public: 730 bool do_heap_region(HeapRegion* r) { 731 r->note_start_of_marking(); 732 return false; 733 } 734 }; 735 736 void G1ConcurrentMark::pre_initial_mark() { 737 // Initialize marking structures. This has to be done in a STW phase. 738 reset(); 739 740 // For each region note start of marking. 741 NoteStartOfMarkHRClosure startcl; 742 _g1h->heap_region_iterate(&startcl); 743 744 _root_regions.reset(); 745 } 746 747 748 void G1ConcurrentMark::post_initial_mark() { 749 // Start Concurrent Marking weak-reference discovery. 750 ReferenceProcessor* rp = _g1h->ref_processor_cm(); 751 // enable ("weak") refs discovery 752 rp->enable_discovery(); 753 rp->setup_policy(false); // snapshot the soft ref policy to be used in this cycle 754 755 SATBMarkQueueSet& satb_mq_set = G1BarrierSet::satb_mark_queue_set(); 756 // This is the start of the marking cycle, we're expected all 757 // threads to have SATB queues with active set to false. 758 satb_mq_set.set_active_all_threads(true, /* new active value */ 759 false /* expected_active */); 760 761 _root_regions.prepare_for_scan(); 762 763 // update_g1_committed() will be called at the end of an evac pause 764 // when marking is on. So, it's also called at the end of the 765 // initial-mark pause to update the heap end, if the heap expands 766 // during it. No need to call it here. 767 } 768 769 /* 770 * Notice that in the next two methods, we actually leave the STS 771 * during the barrier sync and join it immediately afterwards. If we 772 * do not do this, the following deadlock can occur: one thread could 773 * be in the barrier sync code, waiting for the other thread to also 774 * sync up, whereas another one could be trying to yield, while also 775 * waiting for the other threads to sync up too. 776 * 777 * Note, however, that this code is also used during remark and in 778 * this case we should not attempt to leave / enter the STS, otherwise 779 * we'll either hit an assert (debug / fastdebug) or deadlock 780 * (product). So we should only leave / enter the STS if we are 781 * operating concurrently. 782 * 783 * Because the thread that does the sync barrier has left the STS, it 784 * is possible to be suspended for a Full GC or an evacuation pause 785 * could occur. This is actually safe, since the entering the sync 786 * barrier is one of the last things do_marking_step() does, and it 787 * doesn't manipulate any data structures afterwards. 788 */ 789 790 void G1ConcurrentMark::enter_first_sync_barrier(uint worker_id) { 791 bool barrier_aborted; 792 { 793 SuspendibleThreadSetLeaver sts_leave(concurrent()); 794 barrier_aborted = !_first_overflow_barrier_sync.enter(); 795 } 796 797 // at this point everyone should have synced up and not be doing any 798 // more work 799 800 if (barrier_aborted) { 801 // If the barrier aborted we ignore the overflow condition and 802 // just abort the whole marking phase as quickly as possible. 803 return; 804 } 805 } 806 807 void G1ConcurrentMark::enter_second_sync_barrier(uint worker_id) { 808 SuspendibleThreadSetLeaver sts_leave(concurrent()); 809 _second_overflow_barrier_sync.enter(); 810 811 // at this point everything should be re-initialized and ready to go 812 } 813 814 class G1CMConcurrentMarkingTask : public AbstractGangTask { 815 G1ConcurrentMark* _cm; 816 817 public: 818 void work(uint worker_id) { 819 assert(Thread::current()->is_ConcurrentGC_thread(), "Not a concurrent GC thread"); 820 ResourceMark rm; 821 822 double start_vtime = os::elapsedVTime(); 823 824 { 825 SuspendibleThreadSetJoiner sts_join; 826 827 assert(worker_id < _cm->active_tasks(), "invariant"); 828 829 G1CMTask* task = _cm->task(worker_id); 830 task->record_start_time(); 831 if (!_cm->has_aborted()) { 832 do { 833 task->do_marking_step(G1ConcMarkStepDurationMillis, 834 true /* do_termination */, 835 false /* is_serial*/); 836 837 _cm->do_yield_check(); 838 } while (!_cm->has_aborted() && task->has_aborted()); 839 } 840 task->record_end_time(); 841 guarantee(!task->has_aborted() || _cm->has_aborted(), "invariant"); 842 } 843 844 double end_vtime = os::elapsedVTime(); 845 _cm->update_accum_task_vtime(worker_id, end_vtime - start_vtime); 846 } 847 848 G1CMConcurrentMarkingTask(G1ConcurrentMark* cm) : 849 AbstractGangTask("Concurrent Mark"), _cm(cm) { } 850 851 ~G1CMConcurrentMarkingTask() { } 852 }; 853 854 uint G1ConcurrentMark::calc_active_marking_workers() { 855 uint result = 0; 856 if (!UseDynamicNumberOfGCThreads || 857 (!FLAG_IS_DEFAULT(ConcGCThreads) && 858 !ForceDynamicNumberOfGCThreads)) { 859 result = _max_concurrent_workers; 860 } else { 861 result = 862 WorkerPolicy::calc_default_active_workers(_max_concurrent_workers, 863 1, /* Minimum workers */ 864 _num_concurrent_workers, 865 Threads::number_of_non_daemon_threads()); 866 // Don't scale the result down by scale_concurrent_workers() because 867 // that scaling has already gone into "_max_concurrent_workers". 868 } 869 assert(result > 0 && result <= _max_concurrent_workers, 870 "Calculated number of marking workers must be larger than zero and at most the maximum %u, but is %u", 871 _max_concurrent_workers, result); 872 return result; 873 } 874 875 void G1ConcurrentMark::scan_root_region(HeapRegion* hr, uint worker_id) { 876 assert(hr->is_old() || (hr->is_survivor() && hr->next_top_at_mark_start() == hr->bottom()), 877 "Root regions must be old or survivor but region %u is %s", hr->hrm_index(), hr->get_type_str()); 878 G1RootRegionScanClosure cl(_g1h, this, worker_id); 879 880 const uintx interval = PrefetchScanIntervalInBytes; 881 HeapWord* curr = hr->next_top_at_mark_start(); 882 const HeapWord* end = hr->top(); 883 while (curr < end) { 884 Prefetch::read(curr, interval); 885 oop obj = oop(curr); 886 int size = obj->oop_iterate_size(&cl); 887 assert(size == obj->size(), "sanity"); 888 curr += size; 889 } 890 } 891 892 class G1CMRootRegionScanTask : public AbstractGangTask { 893 G1ConcurrentMark* _cm; 894 public: 895 G1CMRootRegionScanTask(G1ConcurrentMark* cm) : 896 AbstractGangTask("G1 Root Region Scan"), _cm(cm) { } 897 898 void work(uint worker_id) { 899 assert(Thread::current()->is_ConcurrentGC_thread(), 900 "this should only be done by a conc GC thread"); 901 902 G1CMRootRegions* root_regions = _cm->root_regions(); 903 HeapRegion* hr = root_regions->claim_next(); 904 while (hr != NULL) { 905 _cm->scan_root_region(hr, worker_id); 906 hr = root_regions->claim_next(); 907 } 908 } 909 }; 910 911 void G1ConcurrentMark::scan_root_regions() { 912 // scan_in_progress() will have been set to true only if there was 913 // at least one root region to scan. So, if it's false, we 914 // should not attempt to do any further work. 915 if (root_regions()->scan_in_progress()) { 916 assert(!has_aborted(), "Aborting before root region scanning is finished not supported."); 917 918 _num_concurrent_workers = MIN2(calc_active_marking_workers(), 919 // We distribute work on a per-region basis, so starting 920 // more threads than that is useless. 921 root_regions()->num_root_regions()); 922 assert(_num_concurrent_workers <= _max_concurrent_workers, 923 "Maximum number of marking threads exceeded"); 924 925 G1CMRootRegionScanTask task(this); 926 log_debug(gc, ergo)("Running %s using %u workers for %u work units.", 927 task.name(), _num_concurrent_workers, root_regions()->num_root_regions()); 928 _concurrent_workers->run_task(&task, _num_concurrent_workers); 929 930 // It's possible that has_aborted() is true here without actually 931 // aborting the survivor scan earlier. This is OK as it's 932 // mainly used for sanity checking. 933 root_regions()->scan_finished(); 934 } 935 } 936 937 void G1ConcurrentMark::concurrent_cycle_start() { 938 _gc_timer_cm->register_gc_start(); 939 940 _gc_tracer_cm->report_gc_start(GCCause::_no_gc /* first parameter is not used */, _gc_timer_cm->gc_start()); 941 942 _g1h->trace_heap_before_gc(_gc_tracer_cm); 943 } 944 945 void G1ConcurrentMark::concurrent_cycle_end() { 946 _g1h->collector_state()->set_clearing_next_bitmap(false); 947 948 _g1h->trace_heap_after_gc(_gc_tracer_cm); 949 950 if (has_aborted()) { 951 log_info(gc, marking)("Concurrent Mark Abort"); 952 _gc_tracer_cm->report_concurrent_mode_failure(); 953 } 954 955 _gc_timer_cm->register_gc_end(); 956 957 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions()); 958 } 959 960 void G1ConcurrentMark::mark_from_roots() { 961 _restart_for_overflow = false; 962 963 _num_concurrent_workers = calc_active_marking_workers(); 964 965 uint active_workers = MAX2(1U, _num_concurrent_workers); 966 967 // Setting active workers is not guaranteed since fewer 968 // worker threads may currently exist and more may not be 969 // available. 970 active_workers = _concurrent_workers->update_active_workers(active_workers); 971 log_info(gc, task)("Using %u workers of %u for marking", active_workers, _concurrent_workers->total_workers()); 972 973 // Parallel task terminator is set in "set_concurrency_and_phase()" 974 set_concurrency_and_phase(active_workers, true /* concurrent */); 975 976 G1CMConcurrentMarkingTask marking_task(this); 977 _concurrent_workers->run_task(&marking_task); 978 print_stats(); 979 } 980 981 void G1ConcurrentMark::verify_during_pause(G1HeapVerifier::G1VerifyType type, VerifyOption vo, const char* caller) { 982 G1HeapVerifier* verifier = _g1h->verifier(); 983 984 verifier->verify_region_sets_optional(); 985 986 if (VerifyDuringGC) { 987 GCTraceTime(Debug, gc, phases) debug(caller, _gc_timer_cm); 988 989 size_t const BufLen = 512; 990 char buffer[BufLen]; 991 992 jio_snprintf(buffer, BufLen, "During GC (%s)", caller); 993 verifier->verify(type, vo, buffer); 994 } 995 996 verifier->check_bitmaps(caller); 997 } 998 999 class G1UpdateRemSetTrackingBeforeRebuildTask : public AbstractGangTask { 1000 G1CollectedHeap* _g1h; 1001 G1ConcurrentMark* _cm; 1002 HeapRegionClaimer _hrclaimer; 1003 uint volatile _total_selected_for_rebuild; 1004 1005 G1PrintRegionLivenessInfoClosure _cl; 1006 1007 class G1UpdateRemSetTrackingBeforeRebuild : public HeapRegionClosure { 1008 G1CollectedHeap* _g1h; 1009 G1ConcurrentMark* _cm; 1010 1011 G1PrintRegionLivenessInfoClosure* _cl; 1012 1013 uint _num_regions_selected_for_rebuild; // The number of regions actually selected for rebuild. 1014 1015 void update_remset_before_rebuild(HeapRegion* hr) { 1016 G1RemSetTrackingPolicy* tracking_policy = _g1h->g1_policy()->remset_tracker(); 1017 1018 bool selected_for_rebuild; 1019 if (hr->is_humongous()) { 1020 bool const is_live = _cm->liveness(hr->humongous_start_region()->hrm_index()) > 0; 1021 selected_for_rebuild = tracking_policy->update_humongous_before_rebuild(hr, is_live); 1022 } else { 1023 size_t const live_bytes = _cm->liveness(hr->hrm_index()); 1024 selected_for_rebuild = tracking_policy->update_before_rebuild(hr, live_bytes); 1025 } 1026 if (selected_for_rebuild) { 1027 _num_regions_selected_for_rebuild++; 1028 } 1029 _cm->update_top_at_rebuild_start(hr); 1030 } 1031 1032 // Distribute the given words across the humongous object starting with hr and 1033 // note end of marking. 1034 void distribute_marked_bytes(HeapRegion* hr, size_t marked_words) { 1035 uint const region_idx = hr->hrm_index(); 1036 size_t const obj_size_in_words = (size_t)oop(hr->bottom())->size(); 1037 uint const num_regions_in_humongous = (uint)G1CollectedHeap::humongous_obj_size_in_regions(obj_size_in_words); 1038 1039 // "Distributing" zero words means that we only note end of marking for these 1040 // regions. 1041 assert(marked_words == 0 || obj_size_in_words == marked_words, 1042 "Marked words should either be 0 or the same as humongous object (" SIZE_FORMAT ") but is " SIZE_FORMAT, 1043 obj_size_in_words, marked_words); 1044 1045 for (uint i = region_idx; i < (region_idx + num_regions_in_humongous); i++) { 1046 HeapRegion* const r = _g1h->region_at(i); 1047 size_t const words_to_add = MIN2(HeapRegion::GrainWords, marked_words); 1048 1049 log_trace(gc, marking)("Adding " SIZE_FORMAT " words to humongous region %u (%s)", 1050 words_to_add, i, r->get_type_str()); 1051 add_marked_bytes_and_note_end(r, words_to_add * HeapWordSize); 1052 marked_words -= words_to_add; 1053 } 1054 assert(marked_words == 0, 1055 SIZE_FORMAT " words left after distributing space across %u regions", 1056 marked_words, num_regions_in_humongous); 1057 } 1058 1059 void update_marked_bytes(HeapRegion* hr) { 1060 uint const region_idx = hr->hrm_index(); 1061 size_t const marked_words = _cm->liveness(region_idx); 1062 // The marking attributes the object's size completely to the humongous starts 1063 // region. We need to distribute this value across the entire set of regions a 1064 // humongous object spans. 1065 if (hr->is_humongous()) { 1066 assert(hr->is_starts_humongous() || marked_words == 0, 1067 "Should not have marked words " SIZE_FORMAT " in non-starts humongous region %u (%s)", 1068 marked_words, region_idx, hr->get_type_str()); 1069 if (hr->is_starts_humongous()) { 1070 distribute_marked_bytes(hr, marked_words); 1071 } 1072 } else { 1073 log_trace(gc, marking)("Adding " SIZE_FORMAT " words to region %u (%s)", marked_words, region_idx, hr->get_type_str()); 1074 add_marked_bytes_and_note_end(hr, marked_words * HeapWordSize); 1075 } 1076 } 1077 1078 void add_marked_bytes_and_note_end(HeapRegion* hr, size_t marked_bytes) { 1079 hr->add_to_marked_bytes(marked_bytes); 1080 _cl->do_heap_region(hr); 1081 hr->note_end_of_marking(); 1082 } 1083 1084 public: 1085 G1UpdateRemSetTrackingBeforeRebuild(G1CollectedHeap* g1h, G1ConcurrentMark* cm, G1PrintRegionLivenessInfoClosure* cl) : 1086 _g1h(g1h), _cm(cm), _cl(cl), _num_regions_selected_for_rebuild(0) { } 1087 1088 virtual bool do_heap_region(HeapRegion* r) { 1089 update_remset_before_rebuild(r); 1090 update_marked_bytes(r); 1091 1092 return false; 1093 } 1094 1095 uint num_selected_for_rebuild() const { return _num_regions_selected_for_rebuild; } 1096 }; 1097 1098 public: 1099 G1UpdateRemSetTrackingBeforeRebuildTask(G1CollectedHeap* g1h, G1ConcurrentMark* cm, uint num_workers) : 1100 AbstractGangTask("G1 Update RemSet Tracking Before Rebuild"), 1101 _g1h(g1h), _cm(cm), _hrclaimer(num_workers), _total_selected_for_rebuild(0), _cl("Post-Marking") { } 1102 1103 virtual void work(uint worker_id) { 1104 G1UpdateRemSetTrackingBeforeRebuild update_cl(_g1h, _cm, &_cl); 1105 _g1h->heap_region_par_iterate_from_worker_offset(&update_cl, &_hrclaimer, worker_id); 1106 Atomic::add(update_cl.num_selected_for_rebuild(), &_total_selected_for_rebuild); 1107 } 1108 1109 uint total_selected_for_rebuild() const { return _total_selected_for_rebuild; } 1110 1111 // Number of regions for which roughly one thread should be spawned for this work. 1112 static const uint RegionsPerThread = 384; 1113 }; 1114 1115 class G1UpdateRemSetTrackingAfterRebuild : public HeapRegionClosure { 1116 G1CollectedHeap* _g1h; 1117 public: 1118 G1UpdateRemSetTrackingAfterRebuild(G1CollectedHeap* g1h) : _g1h(g1h) { } 1119 1120 virtual bool do_heap_region(HeapRegion* r) { 1121 _g1h->g1_policy()->remset_tracker()->update_after_rebuild(r); 1122 return false; 1123 } 1124 }; 1125 1126 void G1ConcurrentMark::remark() { 1127 assert_at_safepoint_on_vm_thread(); 1128 1129 // If a full collection has happened, we should not continue. However we might 1130 // have ended up here as the Remark VM operation has been scheduled already. 1131 if (has_aborted()) { 1132 return; 1133 } 1134 1135 G1Policy* g1p = _g1h->g1_policy(); 1136 g1p->record_concurrent_mark_remark_start(); 1137 1138 double start = os::elapsedTime(); 1139 1140 verify_during_pause(G1HeapVerifier::G1VerifyRemark, VerifyOption_G1UsePrevMarking, "Remark before"); 1141 1142 { 1143 GCTraceTime(Debug, gc, phases) debug("Finalize Marking", _gc_timer_cm); 1144 finalize_marking(); 1145 } 1146 1147 double mark_work_end = os::elapsedTime(); 1148 1149 bool const mark_finished = !has_overflown(); 1150 if (mark_finished) { 1151 weak_refs_work(false /* clear_all_soft_refs */); 1152 1153 SATBMarkQueueSet& satb_mq_set = G1BarrierSet::satb_mark_queue_set(); 1154 // We're done with marking. 1155 // This is the end of the marking cycle, we're expected all 1156 // threads to have SATB queues with active set to true. 1157 satb_mq_set.set_active_all_threads(false, /* new active value */ 1158 true /* expected_active */); 1159 1160 { 1161 GCTraceTime(Debug, gc, phases) debug("Flush Task Caches", _gc_timer_cm); 1162 flush_all_task_caches(); 1163 } 1164 1165 // Install newly created mark bitmap as "prev". 1166 swap_mark_bitmaps(); 1167 { 1168 GCTraceTime(Debug, gc, phases) debug("Update Remembered Set Tracking Before Rebuild", _gc_timer_cm); 1169 1170 uint const workers_by_capacity = (_g1h->num_regions() + G1UpdateRemSetTrackingBeforeRebuildTask::RegionsPerThread - 1) / 1171 G1UpdateRemSetTrackingBeforeRebuildTask::RegionsPerThread; 1172 uint const num_workers = MIN2(_g1h->workers()->active_workers(), workers_by_capacity); 1173 1174 G1UpdateRemSetTrackingBeforeRebuildTask cl(_g1h, this, num_workers); 1175 log_debug(gc,ergo)("Running %s using %u workers for %u regions in heap", cl.name(), num_workers, _g1h->num_regions()); 1176 _g1h->workers()->run_task(&cl, num_workers); 1177 1178 log_debug(gc, remset, tracking)("Remembered Set Tracking update regions total %u, selected %u", 1179 _g1h->num_regions(), cl.total_selected_for_rebuild()); 1180 } 1181 { 1182 GCTraceTime(Debug, gc, phases) debug("Reclaim Empty Regions", _gc_timer_cm); 1183 reclaim_empty_regions(); 1184 } 1185 1186 // Clean out dead classes 1187 if (ClassUnloadingWithConcurrentMark) { 1188 GCTraceTime(Debug, gc, phases) debug("Purge Metaspace", _gc_timer_cm); 1189 ClassLoaderDataGraph::purge(); 1190 } 1191 1192 _g1h->resize_heap_if_necessary(); 1193 1194 compute_new_sizes(); 1195 1196 verify_during_pause(G1HeapVerifier::G1VerifyRemark, VerifyOption_G1UsePrevMarking, "Remark after"); 1197 1198 assert(!restart_for_overflow(), "sanity"); 1199 // Completely reset the marking state since marking completed 1200 reset_at_marking_complete(); 1201 } else { 1202 // We overflowed. Restart concurrent marking. 1203 _restart_for_overflow = true; 1204 1205 verify_during_pause(G1HeapVerifier::G1VerifyRemark, VerifyOption_G1UsePrevMarking, "Remark overflow"); 1206 1207 // Clear the marking state because we will be restarting 1208 // marking due to overflowing the global mark stack. 1209 reset_marking_for_restart(); 1210 } 1211 1212 { 1213 GCTraceTime(Debug, gc, phases) debug("Report Object Count", _gc_timer_cm); 1214 report_object_count(mark_finished); 1215 } 1216 1217 // Statistics 1218 double now = os::elapsedTime(); 1219 _remark_mark_times.add((mark_work_end - start) * 1000.0); 1220 _remark_weak_ref_times.add((now - mark_work_end) * 1000.0); 1221 _remark_times.add((now - start) * 1000.0); 1222 1223 g1p->record_concurrent_mark_remark_end(); 1224 } 1225 1226 class G1ReclaimEmptyRegionsTask : public AbstractGangTask { 1227 // Per-region work during the Cleanup pause. 1228 class G1ReclaimEmptyRegionsClosure : public HeapRegionClosure { 1229 G1CollectedHeap* _g1h; 1230 size_t _freed_bytes; 1231 FreeRegionList* _local_cleanup_list; 1232 uint _old_regions_removed; 1233 uint _humongous_regions_removed; 1234 1235 public: 1236 G1ReclaimEmptyRegionsClosure(G1CollectedHeap* g1h, 1237 FreeRegionList* local_cleanup_list) : 1238 _g1h(g1h), 1239 _freed_bytes(0), 1240 _local_cleanup_list(local_cleanup_list), 1241 _old_regions_removed(0), 1242 _humongous_regions_removed(0) { } 1243 1244 size_t freed_bytes() { return _freed_bytes; } 1245 const uint old_regions_removed() { return _old_regions_removed; } 1246 const uint humongous_regions_removed() { return _humongous_regions_removed; } 1247 1248 bool do_heap_region(HeapRegion *hr) { 1249 if (hr->used() > 0 && hr->max_live_bytes() == 0 && !hr->is_young() && !hr->is_archive()) { 1250 _freed_bytes += hr->used(); 1251 hr->set_containing_set(NULL); 1252 if (hr->is_humongous()) { 1253 _humongous_regions_removed++; 1254 _g1h->free_humongous_region(hr, _local_cleanup_list); 1255 } else { 1256 _old_regions_removed++; 1257 _g1h->free_region(hr, _local_cleanup_list, false /* skip_remset */, false /* skip_hcc */, true /* locked */); 1258 } 1259 hr->clear_cardtable(); 1260 _g1h->concurrent_mark()->clear_statistics_in_region(hr->hrm_index()); 1261 log_trace(gc)("Reclaimed empty region %u (%s) bot " PTR_FORMAT, hr->hrm_index(), hr->get_short_type_str(), p2i(hr->bottom())); 1262 } 1263 1264 return false; 1265 } 1266 }; 1267 1268 G1CollectedHeap* _g1h; 1269 FreeRegionList* _cleanup_list; 1270 HeapRegionClaimer _hrclaimer; 1271 1272 public: 1273 G1ReclaimEmptyRegionsTask(G1CollectedHeap* g1h, FreeRegionList* cleanup_list, uint n_workers) : 1274 AbstractGangTask("G1 Cleanup"), 1275 _g1h(g1h), 1276 _cleanup_list(cleanup_list), 1277 _hrclaimer(n_workers) { 1278 } 1279 1280 void work(uint worker_id) { 1281 FreeRegionList local_cleanup_list("Local Cleanup List"); 1282 G1ReclaimEmptyRegionsClosure cl(_g1h, &local_cleanup_list); 1283 _g1h->heap_region_par_iterate_from_worker_offset(&cl, &_hrclaimer, worker_id); 1284 assert(cl.is_complete(), "Shouldn't have aborted!"); 1285 1286 // Now update the old/humongous region sets 1287 _g1h->remove_from_old_sets(cl.old_regions_removed(), cl.humongous_regions_removed()); 1288 { 1289 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); 1290 _g1h->decrement_summary_bytes(cl.freed_bytes()); 1291 1292 _cleanup_list->add_ordered(&local_cleanup_list); 1293 assert(local_cleanup_list.is_empty(), "post-condition"); 1294 } 1295 } 1296 }; 1297 1298 void G1ConcurrentMark::reclaim_empty_regions() { 1299 WorkGang* workers = _g1h->workers(); 1300 FreeRegionList empty_regions_list("Empty Regions After Mark List"); 1301 1302 G1ReclaimEmptyRegionsTask cl(_g1h, &empty_regions_list, workers->active_workers()); 1303 workers->run_task(&cl); 1304 1305 if (!empty_regions_list.is_empty()) { 1306 log_debug(gc)("Reclaimed %u empty regions", empty_regions_list.length()); 1307 // Now print the empty regions list. 1308 G1HRPrinter* hrp = _g1h->hr_printer(); 1309 if (hrp->is_active()) { 1310 FreeRegionListIterator iter(&empty_regions_list); 1311 while (iter.more_available()) { 1312 HeapRegion* hr = iter.get_next(); 1313 hrp->cleanup(hr); 1314 } 1315 } 1316 // And actually make them available. 1317 _g1h->prepend_to_freelist(&empty_regions_list); 1318 } 1319 } 1320 1321 void G1ConcurrentMark::compute_new_sizes() { 1322 MetaspaceGC::compute_new_size(); 1323 1324 // Cleanup will have freed any regions completely full of garbage. 1325 // Update the soft reference policy with the new heap occupancy. 1326 Universe::update_heap_info_at_gc(); 1327 1328 // We reclaimed old regions so we should calculate the sizes to make 1329 // sure we update the old gen/space data. 1330 _g1h->g1mm()->update_sizes(); 1331 } 1332 1333 void G1ConcurrentMark::cleanup() { 1334 assert_at_safepoint_on_vm_thread(); 1335 1336 // If a full collection has happened, we shouldn't do this. 1337 if (has_aborted()) { 1338 return; 1339 } 1340 1341 G1Policy* g1p = _g1h->g1_policy(); 1342 g1p->record_concurrent_mark_cleanup_start(); 1343 1344 double start = os::elapsedTime(); 1345 1346 verify_during_pause(G1HeapVerifier::G1VerifyCleanup, VerifyOption_G1UsePrevMarking, "Cleanup before"); 1347 1348 { 1349 GCTraceTime(Debug, gc, phases) debug("Update Remembered Set Tracking After Rebuild", _gc_timer_cm); 1350 G1UpdateRemSetTrackingAfterRebuild cl(_g1h); 1351 _g1h->heap_region_iterate(&cl); 1352 } 1353 1354 if (log_is_enabled(Trace, gc, liveness)) { 1355 G1PrintRegionLivenessInfoClosure cl("Post-Cleanup"); 1356 _g1h->heap_region_iterate(&cl); 1357 } 1358 1359 verify_during_pause(G1HeapVerifier::G1VerifyCleanup, VerifyOption_G1UsePrevMarking, "Cleanup after"); 1360 1361 // We need to make this be a "collection" so any collection pause that 1362 // races with it goes around and waits for Cleanup to finish. 1363 _g1h->increment_total_collections(); 1364 1365 // Local statistics 1366 double recent_cleanup_time = (os::elapsedTime() - start); 1367 _total_cleanup_time += recent_cleanup_time; 1368 _cleanup_times.add(recent_cleanup_time); 1369 1370 { 1371 GCTraceTime(Debug, gc, phases) debug("Finalize Concurrent Mark Cleanup", _gc_timer_cm); 1372 _g1h->g1_policy()->record_concurrent_mark_cleanup_end(); 1373 } 1374 } 1375 1376 // 'Keep Alive' oop closure used by both serial parallel reference processing. 1377 // Uses the G1CMTask associated with a worker thread (for serial reference 1378 // processing the G1CMTask for worker 0 is used) to preserve (mark) and 1379 // trace referent objects. 1380 // 1381 // Using the G1CMTask and embedded local queues avoids having the worker 1382 // threads operating on the global mark stack. This reduces the risk 1383 // of overflowing the stack - which we would rather avoid at this late 1384 // state. Also using the tasks' local queues removes the potential 1385 // of the workers interfering with each other that could occur if 1386 // operating on the global stack. 1387 1388 class G1CMKeepAliveAndDrainClosure : public OopClosure { 1389 G1ConcurrentMark* _cm; 1390 G1CMTask* _task; 1391 uint _ref_counter_limit; 1392 uint _ref_counter; 1393 bool _is_serial; 1394 public: 1395 G1CMKeepAliveAndDrainClosure(G1ConcurrentMark* cm, G1CMTask* task, bool is_serial) : 1396 _cm(cm), _task(task), _ref_counter_limit(G1RefProcDrainInterval), 1397 _ref_counter(_ref_counter_limit), _is_serial(is_serial) { 1398 assert(!_is_serial || _task->worker_id() == 0, "only task 0 for serial code"); 1399 } 1400 1401 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 1402 virtual void do_oop( oop* p) { do_oop_work(p); } 1403 1404 template <class T> void do_oop_work(T* p) { 1405 if (_cm->has_overflown()) { 1406 return; 1407 } 1408 if (!_task->deal_with_reference(p)) { 1409 // We did not add anything to the mark bitmap (or mark stack), so there is 1410 // no point trying to drain it. 1411 return; 1412 } 1413 _ref_counter--; 1414 1415 if (_ref_counter == 0) { 1416 // We have dealt with _ref_counter_limit references, pushing them 1417 // and objects reachable from them on to the local stack (and 1418 // possibly the global stack). Call G1CMTask::do_marking_step() to 1419 // process these entries. 1420 // 1421 // We call G1CMTask::do_marking_step() in a loop, which we'll exit if 1422 // there's nothing more to do (i.e. we're done with the entries that 1423 // were pushed as a result of the G1CMTask::deal_with_reference() calls 1424 // above) or we overflow. 1425 // 1426 // Note: G1CMTask::do_marking_step() can set the G1CMTask::has_aborted() 1427 // flag while there may still be some work to do. (See the comment at 1428 // the beginning of G1CMTask::do_marking_step() for those conditions - 1429 // one of which is reaching the specified time target.) It is only 1430 // when G1CMTask::do_marking_step() returns without setting the 1431 // has_aborted() flag that the marking step has completed. 1432 do { 1433 double mark_step_duration_ms = G1ConcMarkStepDurationMillis; 1434 _task->do_marking_step(mark_step_duration_ms, 1435 false /* do_termination */, 1436 _is_serial); 1437 } while (_task->has_aborted() && !_cm->has_overflown()); 1438 _ref_counter = _ref_counter_limit; 1439 } 1440 } 1441 }; 1442 1443 // 'Drain' oop closure used by both serial and parallel reference processing. 1444 // Uses the G1CMTask associated with a given worker thread (for serial 1445 // reference processing the G1CMtask for worker 0 is used). Calls the 1446 // do_marking_step routine, with an unbelievably large timeout value, 1447 // to drain the marking data structures of the remaining entries 1448 // added by the 'keep alive' oop closure above. 1449 1450 class G1CMDrainMarkingStackClosure : public VoidClosure { 1451 G1ConcurrentMark* _cm; 1452 G1CMTask* _task; 1453 bool _is_serial; 1454 public: 1455 G1CMDrainMarkingStackClosure(G1ConcurrentMark* cm, G1CMTask* task, bool is_serial) : 1456 _cm(cm), _task(task), _is_serial(is_serial) { 1457 assert(!_is_serial || _task->worker_id() == 0, "only task 0 for serial code"); 1458 } 1459 1460 void do_void() { 1461 do { 1462 // We call G1CMTask::do_marking_step() to completely drain the local 1463 // and global marking stacks of entries pushed by the 'keep alive' 1464 // oop closure (an instance of G1CMKeepAliveAndDrainClosure above). 1465 // 1466 // G1CMTask::do_marking_step() is called in a loop, which we'll exit 1467 // if there's nothing more to do (i.e. we've completely drained the 1468 // entries that were pushed as a a result of applying the 'keep alive' 1469 // closure to the entries on the discovered ref lists) or we overflow 1470 // the global marking stack. 1471 // 1472 // Note: G1CMTask::do_marking_step() can set the G1CMTask::has_aborted() 1473 // flag while there may still be some work to do. (See the comment at 1474 // the beginning of G1CMTask::do_marking_step() for those conditions - 1475 // one of which is reaching the specified time target.) It is only 1476 // when G1CMTask::do_marking_step() returns without setting the 1477 // has_aborted() flag that the marking step has completed. 1478 1479 _task->do_marking_step(1000000000.0 /* something very large */, 1480 true /* do_termination */, 1481 _is_serial); 1482 } while (_task->has_aborted() && !_cm->has_overflown()); 1483 } 1484 }; 1485 1486 // Implementation of AbstractRefProcTaskExecutor for parallel 1487 // reference processing at the end of G1 concurrent marking 1488 1489 class G1CMRefProcTaskExecutor : public AbstractRefProcTaskExecutor { 1490 private: 1491 G1CollectedHeap* _g1h; 1492 G1ConcurrentMark* _cm; 1493 WorkGang* _workers; 1494 uint _active_workers; 1495 1496 public: 1497 G1CMRefProcTaskExecutor(G1CollectedHeap* g1h, 1498 G1ConcurrentMark* cm, 1499 WorkGang* workers, 1500 uint n_workers) : 1501 _g1h(g1h), _cm(cm), 1502 _workers(workers), _active_workers(n_workers) { } 1503 1504 virtual void execute(ProcessTask& task, uint ergo_workers); 1505 }; 1506 1507 class G1CMRefProcTaskProxy : public AbstractGangTask { 1508 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 1509 ProcessTask& _proc_task; 1510 G1CollectedHeap* _g1h; 1511 G1ConcurrentMark* _cm; 1512 1513 public: 1514 G1CMRefProcTaskProxy(ProcessTask& proc_task, 1515 G1CollectedHeap* g1h, 1516 G1ConcurrentMark* cm) : 1517 AbstractGangTask("Process reference objects in parallel"), 1518 _proc_task(proc_task), _g1h(g1h), _cm(cm) { 1519 ReferenceProcessor* rp = _g1h->ref_processor_cm(); 1520 assert(rp->processing_is_mt(), "shouldn't be here otherwise"); 1521 } 1522 1523 virtual void work(uint worker_id) { 1524 ResourceMark rm; 1525 HandleMark hm; 1526 G1CMTask* task = _cm->task(worker_id); 1527 G1CMIsAliveClosure g1_is_alive(_g1h); 1528 G1CMKeepAliveAndDrainClosure g1_par_keep_alive(_cm, task, false /* is_serial */); 1529 G1CMDrainMarkingStackClosure g1_par_drain(_cm, task, false /* is_serial */); 1530 1531 _proc_task.work(worker_id, g1_is_alive, g1_par_keep_alive, g1_par_drain); 1532 } 1533 }; 1534 1535 void G1CMRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) { 1536 assert(_workers != NULL, "Need parallel worker threads."); 1537 assert(_g1h->ref_processor_cm()->processing_is_mt(), "processing is not MT"); 1538 assert(_workers->active_workers() >= ergo_workers, 1539 "Ergonomically chosen workers(%u) should be less than or equal to active workers(%u)", 1540 ergo_workers, _workers->active_workers()); 1541 1542 G1CMRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _cm); 1543 1544 // We need to reset the concurrency level before each 1545 // proxy task execution, so that the termination protocol 1546 // and overflow handling in G1CMTask::do_marking_step() knows 1547 // how many workers to wait for. 1548 _cm->set_concurrency(ergo_workers); 1549 _workers->run_task(&proc_task_proxy, ergo_workers); 1550 } 1551 1552 void G1ConcurrentMark::weak_refs_work(bool clear_all_soft_refs) { 1553 ResourceMark rm; 1554 HandleMark hm; 1555 1556 // Is alive closure. 1557 G1CMIsAliveClosure g1_is_alive(_g1h); 1558 1559 // Inner scope to exclude the cleaning of the string table 1560 // from the displayed time. 1561 { 1562 GCTraceTime(Debug, gc, phases) debug("Reference Processing", _gc_timer_cm); 1563 1564 ReferenceProcessor* rp = _g1h->ref_processor_cm(); 1565 1566 // See the comment in G1CollectedHeap::ref_processing_init() 1567 // about how reference processing currently works in G1. 1568 1569 // Set the soft reference policy 1570 rp->setup_policy(clear_all_soft_refs); 1571 assert(_global_mark_stack.is_empty(), "mark stack should be empty"); 1572 1573 // Instances of the 'Keep Alive' and 'Complete GC' closures used 1574 // in serial reference processing. Note these closures are also 1575 // used for serially processing (by the the current thread) the 1576 // JNI references during parallel reference processing. 1577 // 1578 // These closures do not need to synchronize with the worker 1579 // threads involved in parallel reference processing as these 1580 // instances are executed serially by the current thread (e.g. 1581 // reference processing is not multi-threaded and is thus 1582 // performed by the current thread instead of a gang worker). 1583 // 1584 // The gang tasks involved in parallel reference processing create 1585 // their own instances of these closures, which do their own 1586 // synchronization among themselves. 1587 G1CMKeepAliveAndDrainClosure g1_keep_alive(this, task(0), true /* is_serial */); 1588 G1CMDrainMarkingStackClosure g1_drain_mark_stack(this, task(0), true /* is_serial */); 1589 1590 // We need at least one active thread. If reference processing 1591 // is not multi-threaded we use the current (VMThread) thread, 1592 // otherwise we use the work gang from the G1CollectedHeap and 1593 // we utilize all the worker threads we can. 1594 bool processing_is_mt = rp->processing_is_mt(); 1595 uint active_workers = (processing_is_mt ? _g1h->workers()->active_workers() : 1U); 1596 active_workers = MAX2(MIN2(active_workers, _max_num_tasks), 1U); 1597 1598 // Parallel processing task executor. 1599 G1CMRefProcTaskExecutor par_task_executor(_g1h, this, 1600 _g1h->workers(), active_workers); 1601 AbstractRefProcTaskExecutor* executor = (processing_is_mt ? &par_task_executor : NULL); 1602 1603 // Set the concurrency level. The phase was already set prior to 1604 // executing the remark task. 1605 set_concurrency(active_workers); 1606 1607 // Set the degree of MT processing here. If the discovery was done MT, 1608 // the number of threads involved during discovery could differ from 1609 // the number of active workers. This is OK as long as the discovered 1610 // Reference lists are balanced (see balance_all_queues() and balance_queues()). 1611 rp->set_active_mt_degree(active_workers); 1612 1613 ReferenceProcessorPhaseTimes pt(_gc_timer_cm, rp->max_num_queues()); 1614 1615 // Process the weak references. 1616 const ReferenceProcessorStats& stats = 1617 rp->process_discovered_references(&g1_is_alive, 1618 &g1_keep_alive, 1619 &g1_drain_mark_stack, 1620 executor, 1621 &pt); 1622 _gc_tracer_cm->report_gc_reference_stats(stats); 1623 pt.print_all_references(); 1624 1625 // The do_oop work routines of the keep_alive and drain_marking_stack 1626 // oop closures will set the has_overflown flag if we overflow the 1627 // global marking stack. 1628 1629 assert(has_overflown() || _global_mark_stack.is_empty(), 1630 "Mark stack should be empty (unless it has overflown)"); 1631 1632 assert(rp->num_queues() == active_workers, "why not"); 1633 1634 rp->verify_no_references_recorded(); 1635 assert(!rp->discovery_enabled(), "Post condition"); 1636 } 1637 1638 if (has_overflown()) { 1639 // We can not trust g1_is_alive and the contents of the heap if the marking stack 1640 // overflowed while processing references. Exit the VM. 1641 fatal("Overflow during reference processing, can not continue. Please " 1642 "increase MarkStackSizeMax (current value: " SIZE_FORMAT ") and " 1643 "restart.", MarkStackSizeMax); 1644 return; 1645 } 1646 1647 assert(_global_mark_stack.is_empty(), "Marking should have completed"); 1648 1649 { 1650 GCTraceTime(Debug, gc, phases) debug("Weak Processing", _gc_timer_cm); 1651 WeakProcessor::weak_oops_do(_g1h->workers(), &g1_is_alive, &do_nothing_cl, 1); 1652 } 1653 1654 // Unload Klasses, String, Code Cache, etc. 1655 if (ClassUnloadingWithConcurrentMark) { 1656 GCTraceTime(Debug, gc, phases) debug("Class Unloading", _gc_timer_cm); 1657 bool purged_classes = SystemDictionary::do_unloading(_gc_timer_cm); 1658 _g1h->complete_cleaning(&g1_is_alive, purged_classes); 1659 } else if (StringDedup::is_enabled()) { 1660 GCTraceTime(Debug, gc, phases) debug("String Deduplication", _gc_timer_cm); 1661 _g1h->string_dedup_cleaning(&g1_is_alive, NULL); 1662 } 1663 } 1664 1665 class G1PrecleanYieldClosure : public YieldClosure { 1666 G1ConcurrentMark* _cm; 1667 1668 public: 1669 G1PrecleanYieldClosure(G1ConcurrentMark* cm) : _cm(cm) { } 1670 1671 virtual bool should_return() { 1672 return _cm->has_aborted(); 1673 } 1674 1675 virtual bool should_return_fine_grain() { 1676 _cm->do_yield_check(); 1677 return _cm->has_aborted(); 1678 } 1679 }; 1680 1681 void G1ConcurrentMark::preclean() { 1682 assert(G1UseReferencePrecleaning, "Precleaning must be enabled."); 1683 1684 SuspendibleThreadSetJoiner joiner; 1685 1686 G1CMKeepAliveAndDrainClosure keep_alive(this, task(0), true /* is_serial */); 1687 G1CMDrainMarkingStackClosure drain_mark_stack(this, task(0), true /* is_serial */); 1688 1689 set_concurrency_and_phase(1, true); 1690 1691 G1PrecleanYieldClosure yield_cl(this); 1692 1693 ReferenceProcessor* rp = _g1h->ref_processor_cm(); 1694 // Precleaning is single threaded. Temporarily disable MT discovery. 1695 ReferenceProcessorMTDiscoveryMutator rp_mut_discovery(rp, false); 1696 rp->preclean_discovered_references(rp->is_alive_non_header(), 1697 &keep_alive, 1698 &drain_mark_stack, 1699 &yield_cl, 1700 _gc_timer_cm); 1701 } 1702 1703 // When sampling object counts, we already swapped the mark bitmaps, so we need to use 1704 // the prev bitmap determining liveness. 1705 class G1ObjectCountIsAliveClosure: public BoolObjectClosure { 1706 G1CollectedHeap* _g1h; 1707 public: 1708 G1ObjectCountIsAliveClosure(G1CollectedHeap* g1h) : _g1h(g1h) { } 1709 1710 bool do_object_b(oop obj) { 1711 HeapWord* addr = (HeapWord*)obj; 1712 return addr != NULL && 1713 (!_g1h->is_in_g1_reserved(addr) || !_g1h->is_obj_dead(obj)); 1714 } 1715 }; 1716 1717 void G1ConcurrentMark::report_object_count(bool mark_completed) { 1718 // Depending on the completion of the marking liveness needs to be determined 1719 // using either the next or prev bitmap. 1720 if (mark_completed) { 1721 G1ObjectCountIsAliveClosure is_alive(_g1h); 1722 _gc_tracer_cm->report_object_count_after_gc(&is_alive); 1723 } else { 1724 G1CMIsAliveClosure is_alive(_g1h); 1725 _gc_tracer_cm->report_object_count_after_gc(&is_alive); 1726 } 1727 } 1728 1729 1730 void G1ConcurrentMark::swap_mark_bitmaps() { 1731 G1CMBitMap* temp = _prev_mark_bitmap; 1732 _prev_mark_bitmap = _next_mark_bitmap; 1733 _next_mark_bitmap = temp; 1734 _g1h->collector_state()->set_clearing_next_bitmap(true); 1735 } 1736 1737 // Closure for marking entries in SATB buffers. 1738 class G1CMSATBBufferClosure : public SATBBufferClosure { 1739 private: 1740 G1CMTask* _task; 1741 G1CollectedHeap* _g1h; 1742 1743 // This is very similar to G1CMTask::deal_with_reference, but with 1744 // more relaxed requirements for the argument, so this must be more 1745 // circumspect about treating the argument as an object. 1746 void do_entry(void* entry) const { 1747 _task->increment_refs_reached(); 1748 oop const obj = static_cast<oop>(entry); 1749 _task->make_reference_grey(obj); 1750 } 1751 1752 public: 1753 G1CMSATBBufferClosure(G1CMTask* task, G1CollectedHeap* g1h) 1754 : _task(task), _g1h(g1h) { } 1755 1756 virtual void do_buffer(void** buffer, size_t size) { 1757 for (size_t i = 0; i < size; ++i) { 1758 do_entry(buffer[i]); 1759 } 1760 } 1761 }; 1762 1763 class G1RemarkThreadsClosure : public ThreadClosure { 1764 G1CMSATBBufferClosure _cm_satb_cl; 1765 G1CMOopClosure _cm_cl; 1766 MarkingCodeBlobClosure _code_cl; 1767 int _thread_parity; 1768 1769 public: 1770 G1RemarkThreadsClosure(G1CollectedHeap* g1h, G1CMTask* task) : 1771 _cm_satb_cl(task, g1h), 1772 _cm_cl(g1h, task), 1773 _code_cl(&_cm_cl, !CodeBlobToOopClosure::FixRelocations), 1774 _thread_parity(Threads::thread_claim_parity()) {} 1775 1776 void do_thread(Thread* thread) { 1777 if (thread->claim_oops_do(true, _thread_parity)) { 1778 SATBMarkQueue& queue = G1ThreadLocalData::satb_mark_queue(thread); 1779 queue.apply_closure_and_empty(&_cm_satb_cl); 1780 if (thread->is_Java_thread()) { 1781 // In theory it should not be neccessary to explicitly walk the nmethods to find roots for concurrent marking 1782 // however the liveness of oops reachable from nmethods have very complex lifecycles: 1783 // * Alive if on the stack of an executing method 1784 // * Weakly reachable otherwise 1785 // Some objects reachable from nmethods, such as the class loader (or klass_holder) of the receiver should be 1786 // live by the SATB invariant but other oops recorded in nmethods may behave differently. 1787 JavaThread* jt = (JavaThread*)thread; 1788 jt->nmethods_do(&_code_cl); 1789 } 1790 } 1791 } 1792 }; 1793 1794 class G1CMRemarkTask : public AbstractGangTask { 1795 G1ConcurrentMark* _cm; 1796 public: 1797 void work(uint worker_id) { 1798 G1CMTask* task = _cm->task(worker_id); 1799 task->record_start_time(); 1800 { 1801 ResourceMark rm; 1802 HandleMark hm; 1803 1804 G1RemarkThreadsClosure threads_f(G1CollectedHeap::heap(), task); 1805 Threads::threads_do(&threads_f); 1806 } 1807 1808 do { 1809 task->do_marking_step(1000000000.0 /* something very large */, 1810 true /* do_termination */, 1811 false /* is_serial */); 1812 } while (task->has_aborted() && !_cm->has_overflown()); 1813 // If we overflow, then we do not want to restart. We instead 1814 // want to abort remark and do concurrent marking again. 1815 task->record_end_time(); 1816 } 1817 1818 G1CMRemarkTask(G1ConcurrentMark* cm, uint active_workers) : 1819 AbstractGangTask("Par Remark"), _cm(cm) { 1820 _cm->terminator()->reset_for_reuse(active_workers); 1821 } 1822 }; 1823 1824 void G1ConcurrentMark::finalize_marking() { 1825 ResourceMark rm; 1826 HandleMark hm; 1827 1828 _g1h->ensure_parsability(false); 1829 1830 // this is remark, so we'll use up all active threads 1831 uint active_workers = _g1h->workers()->active_workers(); 1832 set_concurrency_and_phase(active_workers, false /* concurrent */); 1833 // Leave _parallel_marking_threads at it's 1834 // value originally calculated in the G1ConcurrentMark 1835 // constructor and pass values of the active workers 1836 // through the gang in the task. 1837 1838 { 1839 StrongRootsScope srs(active_workers); 1840 1841 G1CMRemarkTask remarkTask(this, active_workers); 1842 // We will start all available threads, even if we decide that the 1843 // active_workers will be fewer. The extra ones will just bail out 1844 // immediately. 1845 _g1h->workers()->run_task(&remarkTask); 1846 } 1847 1848 SATBMarkQueueSet& satb_mq_set = G1BarrierSet::satb_mark_queue_set(); 1849 guarantee(has_overflown() || 1850 satb_mq_set.completed_buffers_num() == 0, 1851 "Invariant: has_overflown = %s, num buffers = " SIZE_FORMAT, 1852 BOOL_TO_STR(has_overflown()), 1853 satb_mq_set.completed_buffers_num()); 1854 1855 print_stats(); 1856 } 1857 1858 void G1ConcurrentMark::flush_all_task_caches() { 1859 size_t hits = 0; 1860 size_t misses = 0; 1861 for (uint i = 0; i < _max_num_tasks; i++) { 1862 Pair<size_t, size_t> stats = _tasks[i]->flush_mark_stats_cache(); 1863 hits += stats.first; 1864 misses += stats.second; 1865 } 1866 size_t sum = hits + misses; 1867 log_debug(gc, stats)("Mark stats cache hits " SIZE_FORMAT " misses " SIZE_FORMAT " ratio %1.3lf", 1868 hits, misses, percent_of(hits, sum)); 1869 } 1870 1871 void G1ConcurrentMark::clear_range_in_prev_bitmap(MemRegion mr) { 1872 _prev_mark_bitmap->clear_range(mr); 1873 } 1874 1875 HeapRegion* 1876 G1ConcurrentMark::claim_region(uint worker_id) { 1877 // "checkpoint" the finger 1878 HeapWord* finger = _finger; 1879 1880 while (finger < _heap.end()) { 1881 assert(_g1h->is_in_g1_reserved(finger), "invariant"); 1882 1883 HeapRegion* curr_region = _g1h->heap_region_containing(finger); 1884 // Make sure that the reads below do not float before loading curr_region. 1885 OrderAccess::loadload(); 1886 // Above heap_region_containing may return NULL as we always scan claim 1887 // until the end of the heap. In this case, just jump to the next region. 1888 HeapWord* end = curr_region != NULL ? curr_region->end() : finger + HeapRegion::GrainWords; 1889 1890 // Is the gap between reading the finger and doing the CAS too long? 1891 HeapWord* res = Atomic::cmpxchg(end, &_finger, finger); 1892 if (res == finger && curr_region != NULL) { 1893 // we succeeded 1894 HeapWord* bottom = curr_region->bottom(); 1895 HeapWord* limit = curr_region->next_top_at_mark_start(); 1896 1897 // notice that _finger == end cannot be guaranteed here since, 1898 // someone else might have moved the finger even further 1899 assert(_finger >= end, "the finger should have moved forward"); 1900 1901 if (limit > bottom) { 1902 return curr_region; 1903 } else { 1904 assert(limit == bottom, 1905 "the region limit should be at bottom"); 1906 // we return NULL and the caller should try calling 1907 // claim_region() again. 1908 return NULL; 1909 } 1910 } else { 1911 assert(_finger > finger, "the finger should have moved forward"); 1912 // read it again 1913 finger = _finger; 1914 } 1915 } 1916 1917 return NULL; 1918 } 1919 1920 #ifndef PRODUCT 1921 class VerifyNoCSetOops { 1922 G1CollectedHeap* _g1h; 1923 const char* _phase; 1924 int _info; 1925 1926 public: 1927 VerifyNoCSetOops(const char* phase, int info = -1) : 1928 _g1h(G1CollectedHeap::heap()), 1929 _phase(phase), 1930 _info(info) 1931 { } 1932 1933 void operator()(G1TaskQueueEntry task_entry) const { 1934 if (task_entry.is_array_slice()) { 1935 guarantee(_g1h->is_in_reserved(task_entry.slice()), "Slice " PTR_FORMAT " must be in heap.", p2i(task_entry.slice())); 1936 return; 1937 } 1938 guarantee(oopDesc::is_oop(task_entry.obj()), 1939 "Non-oop " PTR_FORMAT ", phase: %s, info: %d", 1940 p2i(task_entry.obj()), _phase, _info); 1941 guarantee(!_g1h->is_in_cset(task_entry.obj()), 1942 "obj: " PTR_FORMAT " in CSet, phase: %s, info: %d", 1943 p2i(task_entry.obj()), _phase, _info); 1944 } 1945 }; 1946 1947 void G1ConcurrentMark::verify_no_cset_oops() { 1948 assert(SafepointSynchronize::is_at_safepoint(), "should be at a safepoint"); 1949 if (!_g1h->collector_state()->mark_or_rebuild_in_progress()) { 1950 return; 1951 } 1952 1953 // Verify entries on the global mark stack 1954 _global_mark_stack.iterate(VerifyNoCSetOops("Stack")); 1955 1956 // Verify entries on the task queues 1957 for (uint i = 0; i < _max_num_tasks; ++i) { 1958 G1CMTaskQueue* queue = _task_queues->queue(i); 1959 queue->iterate(VerifyNoCSetOops("Queue", i)); 1960 } 1961 1962 // Verify the global finger 1963 HeapWord* global_finger = finger(); 1964 if (global_finger != NULL && global_finger < _heap.end()) { 1965 // Since we always iterate over all regions, we might get a NULL HeapRegion 1966 // here. 1967 HeapRegion* global_hr = _g1h->heap_region_containing(global_finger); 1968 guarantee(global_hr == NULL || global_finger == global_hr->bottom(), 1969 "global finger: " PTR_FORMAT " region: " HR_FORMAT, 1970 p2i(global_finger), HR_FORMAT_PARAMS(global_hr)); 1971 } 1972 1973 // Verify the task fingers 1974 assert(_num_concurrent_workers <= _max_num_tasks, "sanity"); 1975 for (uint i = 0; i < _num_concurrent_workers; ++i) { 1976 G1CMTask* task = _tasks[i]; 1977 HeapWord* task_finger = task->finger(); 1978 if (task_finger != NULL && task_finger < _heap.end()) { 1979 // See above note on the global finger verification. 1980 HeapRegion* task_hr = _g1h->heap_region_containing(task_finger); 1981 guarantee(task_hr == NULL || task_finger == task_hr->bottom() || 1982 !task_hr->in_collection_set(), 1983 "task finger: " PTR_FORMAT " region: " HR_FORMAT, 1984 p2i(task_finger), HR_FORMAT_PARAMS(task_hr)); 1985 } 1986 } 1987 } 1988 #endif // PRODUCT 1989 1990 void G1ConcurrentMark::rebuild_rem_set_concurrently() { 1991 _g1h->g1_rem_set()->rebuild_rem_set(this, _concurrent_workers, _worker_id_offset); 1992 } 1993 1994 void G1ConcurrentMark::print_stats() { 1995 if (!log_is_enabled(Debug, gc, stats)) { 1996 return; 1997 } 1998 log_debug(gc, stats)("---------------------------------------------------------------------"); 1999 for (size_t i = 0; i < _num_active_tasks; ++i) { 2000 _tasks[i]->print_stats(); 2001 log_debug(gc, stats)("---------------------------------------------------------------------"); 2002 } 2003 } 2004 2005 void G1ConcurrentMark::concurrent_cycle_abort() { 2006 if (!cm_thread()->during_cycle() || _has_aborted) { 2007 // We haven't started a concurrent cycle or we have already aborted it. No need to do anything. 2008 return; 2009 } 2010 2011 // Clear all marks in the next bitmap for the next marking cycle. This will allow us to skip the next 2012 // concurrent bitmap clearing. 2013 { 2014 GCTraceTime(Debug, gc) debug("Clear Next Bitmap"); 2015 clear_bitmap(_next_mark_bitmap, _g1h->workers(), false); 2016 } 2017 // Note we cannot clear the previous marking bitmap here 2018 // since VerifyDuringGC verifies the objects marked during 2019 // a full GC against the previous bitmap. 2020 2021 // Empty mark stack 2022 reset_marking_for_restart(); 2023 for (uint i = 0; i < _max_num_tasks; ++i) { 2024 _tasks[i]->clear_region_fields(); 2025 } 2026 _first_overflow_barrier_sync.abort(); 2027 _second_overflow_barrier_sync.abort(); 2028 _has_aborted = true; 2029 2030 SATBMarkQueueSet& satb_mq_set = G1BarrierSet::satb_mark_queue_set(); 2031 satb_mq_set.abandon_partial_marking(); 2032 // This can be called either during or outside marking, we'll read 2033 // the expected_active value from the SATB queue set. 2034 satb_mq_set.set_active_all_threads( 2035 false, /* new active value */ 2036 satb_mq_set.is_active() /* expected_active */); 2037 } 2038 2039 static void print_ms_time_info(const char* prefix, const char* name, 2040 NumberSeq& ns) { 2041 log_trace(gc, marking)("%s%5d %12s: total time = %8.2f s (avg = %8.2f ms).", 2042 prefix, ns.num(), name, ns.sum()/1000.0, ns.avg()); 2043 if (ns.num() > 0) { 2044 log_trace(gc, marking)("%s [std. dev = %8.2f ms, max = %8.2f ms]", 2045 prefix, ns.sd(), ns.maximum()); 2046 } 2047 } 2048 2049 void G1ConcurrentMark::print_summary_info() { 2050 Log(gc, marking) log; 2051 if (!log.is_trace()) { 2052 return; 2053 } 2054 2055 log.trace(" Concurrent marking:"); 2056 print_ms_time_info(" ", "init marks", _init_times); 2057 print_ms_time_info(" ", "remarks", _remark_times); 2058 { 2059 print_ms_time_info(" ", "final marks", _remark_mark_times); 2060 print_ms_time_info(" ", "weak refs", _remark_weak_ref_times); 2061 2062 } 2063 print_ms_time_info(" ", "cleanups", _cleanup_times); 2064 log.trace(" Finalize live data total time = %8.2f s (avg = %8.2f ms).", 2065 _total_cleanup_time, (_cleanup_times.num() > 0 ? _total_cleanup_time * 1000.0 / (double)_cleanup_times.num() : 0.0)); 2066 log.trace(" Total stop_world time = %8.2f s.", 2067 (_init_times.sum() + _remark_times.sum() + _cleanup_times.sum())/1000.0); 2068 log.trace(" Total concurrent time = %8.2f s (%8.2f s marking).", 2069 cm_thread()->vtime_accum(), cm_thread()->vtime_mark_accum()); 2070 } 2071 2072 void G1ConcurrentMark::print_worker_threads_on(outputStream* st) const { 2073 _concurrent_workers->print_worker_threads_on(st); 2074 } 2075 2076 void G1ConcurrentMark::threads_do(ThreadClosure* tc) const { 2077 _concurrent_workers->threads_do(tc); 2078 } 2079 2080 void G1ConcurrentMark::print_on_error(outputStream* st) const { 2081 st->print_cr("Marking Bits (Prev, Next): (CMBitMap*) " PTR_FORMAT ", (CMBitMap*) " PTR_FORMAT, 2082 p2i(_prev_mark_bitmap), p2i(_next_mark_bitmap)); 2083 _prev_mark_bitmap->print_on_error(st, " Prev Bits: "); 2084 _next_mark_bitmap->print_on_error(st, " Next Bits: "); 2085 } 2086 2087 static ReferenceProcessor* get_cm_oop_closure_ref_processor(G1CollectedHeap* g1h) { 2088 ReferenceProcessor* result = g1h->ref_processor_cm(); 2089 assert(result != NULL, "CM reference processor should not be NULL"); 2090 return result; 2091 } 2092 2093 G1CMOopClosure::G1CMOopClosure(G1CollectedHeap* g1h, 2094 G1CMTask* task) 2095 : MetadataVisitingOopIterateClosure(get_cm_oop_closure_ref_processor(g1h)), 2096 _g1h(g1h), _task(task) 2097 { } 2098 2099 void G1CMTask::setup_for_region(HeapRegion* hr) { 2100 assert(hr != NULL, 2101 "claim_region() should have filtered out NULL regions"); 2102 _curr_region = hr; 2103 _finger = hr->bottom(); 2104 update_region_limit(); 2105 } 2106 2107 void G1CMTask::update_region_limit() { 2108 HeapRegion* hr = _curr_region; 2109 HeapWord* bottom = hr->bottom(); 2110 HeapWord* limit = hr->next_top_at_mark_start(); 2111 2112 if (limit == bottom) { 2113 // The region was collected underneath our feet. 2114 // We set the finger to bottom to ensure that the bitmap 2115 // iteration that will follow this will not do anything. 2116 // (this is not a condition that holds when we set the region up, 2117 // as the region is not supposed to be empty in the first place) 2118 _finger = bottom; 2119 } else if (limit >= _region_limit) { 2120 assert(limit >= _finger, "peace of mind"); 2121 } else { 2122 assert(limit < _region_limit, "only way to get here"); 2123 // This can happen under some pretty unusual circumstances. An 2124 // evacuation pause empties the region underneath our feet (NTAMS 2125 // at bottom). We then do some allocation in the region (NTAMS 2126 // stays at bottom), followed by the region being used as a GC 2127 // alloc region (NTAMS will move to top() and the objects 2128 // originally below it will be grayed). All objects now marked in 2129 // the region are explicitly grayed, if below the global finger, 2130 // and we do not need in fact to scan anything else. So, we simply 2131 // set _finger to be limit to ensure that the bitmap iteration 2132 // doesn't do anything. 2133 _finger = limit; 2134 } 2135 2136 _region_limit = limit; 2137 } 2138 2139 void G1CMTask::giveup_current_region() { 2140 assert(_curr_region != NULL, "invariant"); 2141 clear_region_fields(); 2142 } 2143 2144 void G1CMTask::clear_region_fields() { 2145 // Values for these three fields that indicate that we're not 2146 // holding on to a region. 2147 _curr_region = NULL; 2148 _finger = NULL; 2149 _region_limit = NULL; 2150 } 2151 2152 void G1CMTask::set_cm_oop_closure(G1CMOopClosure* cm_oop_closure) { 2153 if (cm_oop_closure == NULL) { 2154 assert(_cm_oop_closure != NULL, "invariant"); 2155 } else { 2156 assert(_cm_oop_closure == NULL, "invariant"); 2157 } 2158 _cm_oop_closure = cm_oop_closure; 2159 } 2160 2161 void G1CMTask::reset(G1CMBitMap* next_mark_bitmap) { 2162 guarantee(next_mark_bitmap != NULL, "invariant"); 2163 _next_mark_bitmap = next_mark_bitmap; 2164 clear_region_fields(); 2165 2166 _calls = 0; 2167 _elapsed_time_ms = 0.0; 2168 _termination_time_ms = 0.0; 2169 _termination_start_time_ms = 0.0; 2170 2171 _mark_stats_cache.reset(); 2172 } 2173 2174 bool G1CMTask::should_exit_termination() { 2175 if (!regular_clock_call()) { 2176 return true; 2177 } 2178 2179 // This is called when we are in the termination protocol. We should 2180 // quit if, for some reason, this task wants to abort or the global 2181 // stack is not empty (this means that we can get work from it). 2182 return !_cm->mark_stack_empty() || has_aborted(); 2183 } 2184 2185 void G1CMTask::reached_limit() { 2186 assert(_words_scanned >= _words_scanned_limit || 2187 _refs_reached >= _refs_reached_limit , 2188 "shouldn't have been called otherwise"); 2189 abort_marking_if_regular_check_fail(); 2190 } 2191 2192 bool G1CMTask::regular_clock_call() { 2193 if (has_aborted()) { 2194 return false; 2195 } 2196 2197 // First, we need to recalculate the words scanned and refs reached 2198 // limits for the next clock call. 2199 recalculate_limits(); 2200 2201 // During the regular clock call we do the following 2202 2203 // (1) If an overflow has been flagged, then we abort. 2204 if (_cm->has_overflown()) { 2205 return false; 2206 } 2207 2208 // If we are not concurrent (i.e. we're doing remark) we don't need 2209 // to check anything else. The other steps are only needed during 2210 // the concurrent marking phase. 2211 if (!_cm->concurrent()) { 2212 return true; 2213 } 2214 2215 // (2) If marking has been aborted for Full GC, then we also abort. 2216 if (_cm->has_aborted()) { 2217 return false; 2218 } 2219 2220 double curr_time_ms = os::elapsedVTime() * 1000.0; 2221 2222 // (4) We check whether we should yield. If we have to, then we abort. 2223 if (SuspendibleThreadSet::should_yield()) { 2224 // We should yield. To do this we abort the task. The caller is 2225 // responsible for yielding. 2226 return false; 2227 } 2228 2229 // (5) We check whether we've reached our time quota. If we have, 2230 // then we abort. 2231 double elapsed_time_ms = curr_time_ms - _start_time_ms; 2232 if (elapsed_time_ms > _time_target_ms) { 2233 _has_timed_out = true; 2234 return false; 2235 } 2236 2237 // (6) Finally, we check whether there are enough completed STAB 2238 // buffers available for processing. If there are, we abort. 2239 SATBMarkQueueSet& satb_mq_set = G1BarrierSet::satb_mark_queue_set(); 2240 if (!_draining_satb_buffers && satb_mq_set.process_completed_buffers()) { 2241 // we do need to process SATB buffers, we'll abort and restart 2242 // the marking task to do so 2243 return false; 2244 } 2245 return true; 2246 } 2247 2248 void G1CMTask::recalculate_limits() { 2249 _real_words_scanned_limit = _words_scanned + words_scanned_period; 2250 _words_scanned_limit = _real_words_scanned_limit; 2251 2252 _real_refs_reached_limit = _refs_reached + refs_reached_period; 2253 _refs_reached_limit = _real_refs_reached_limit; 2254 } 2255 2256 void G1CMTask::decrease_limits() { 2257 // This is called when we believe that we're going to do an infrequent 2258 // operation which will increase the per byte scanned cost (i.e. move 2259 // entries to/from the global stack). It basically tries to decrease the 2260 // scanning limit so that the clock is called earlier. 2261 2262 _words_scanned_limit = _real_words_scanned_limit - 3 * words_scanned_period / 4; 2263 _refs_reached_limit = _real_refs_reached_limit - 3 * refs_reached_period / 4; 2264 } 2265 2266 void G1CMTask::move_entries_to_global_stack() { 2267 // Local array where we'll store the entries that will be popped 2268 // from the local queue. 2269 G1TaskQueueEntry buffer[G1CMMarkStack::EntriesPerChunk]; 2270 2271 size_t n = 0; 2272 G1TaskQueueEntry task_entry; 2273 while (n < G1CMMarkStack::EntriesPerChunk && _task_queue->pop_local(task_entry)) { 2274 buffer[n] = task_entry; 2275 ++n; 2276 } 2277 if (n < G1CMMarkStack::EntriesPerChunk) { 2278 buffer[n] = G1TaskQueueEntry(); 2279 } 2280 2281 if (n > 0) { 2282 if (!_cm->mark_stack_push(buffer)) { 2283 set_has_aborted(); 2284 } 2285 } 2286 2287 // This operation was quite expensive, so decrease the limits. 2288 decrease_limits(); 2289 } 2290 2291 bool G1CMTask::get_entries_from_global_stack() { 2292 // Local array where we'll store the entries that will be popped 2293 // from the global stack. 2294 G1TaskQueueEntry buffer[G1CMMarkStack::EntriesPerChunk]; 2295 2296 if (!_cm->mark_stack_pop(buffer)) { 2297 return false; 2298 } 2299 2300 // We did actually pop at least one entry. 2301 for (size_t i = 0; i < G1CMMarkStack::EntriesPerChunk; ++i) { 2302 G1TaskQueueEntry task_entry = buffer[i]; 2303 if (task_entry.is_null()) { 2304 break; 2305 } 2306 assert(task_entry.is_array_slice() || oopDesc::is_oop(task_entry.obj()), "Element " PTR_FORMAT " must be an array slice or oop", p2i(task_entry.obj())); 2307 bool success = _task_queue->push(task_entry); 2308 // We only call this when the local queue is empty or under a 2309 // given target limit. So, we do not expect this push to fail. 2310 assert(success, "invariant"); 2311 } 2312 2313 // This operation was quite expensive, so decrease the limits 2314 decrease_limits(); 2315 return true; 2316 } 2317 2318 void G1CMTask::drain_local_queue(bool partially) { 2319 if (has_aborted()) { 2320 return; 2321 } 2322 2323 // Decide what the target size is, depending whether we're going to 2324 // drain it partially (so that other tasks can steal if they run out 2325 // of things to do) or totally (at the very end). 2326 size_t target_size; 2327 if (partially) { 2328 target_size = MIN2((size_t)_task_queue->max_elems()/3, (size_t)GCDrainStackTargetSize); 2329 } else { 2330 target_size = 0; 2331 } 2332 2333 if (_task_queue->size() > target_size) { 2334 G1TaskQueueEntry entry; 2335 bool ret = _task_queue->pop_local(entry); 2336 while (ret) { 2337 scan_task_entry(entry); 2338 if (_task_queue->size() <= target_size || has_aborted()) { 2339 ret = false; 2340 } else { 2341 ret = _task_queue->pop_local(entry); 2342 } 2343 } 2344 } 2345 } 2346 2347 void G1CMTask::drain_global_stack(bool partially) { 2348 if (has_aborted()) { 2349 return; 2350 } 2351 2352 // We have a policy to drain the local queue before we attempt to 2353 // drain the global stack. 2354 assert(partially || _task_queue->size() == 0, "invariant"); 2355 2356 // Decide what the target size is, depending whether we're going to 2357 // drain it partially (so that other tasks can steal if they run out 2358 // of things to do) or totally (at the very end). 2359 // Notice that when draining the global mark stack partially, due to the racyness 2360 // of the mark stack size update we might in fact drop below the target. But, 2361 // this is not a problem. 2362 // In case of total draining, we simply process until the global mark stack is 2363 // totally empty, disregarding the size counter. 2364 if (partially) { 2365 size_t const target_size = _cm->partial_mark_stack_size_target(); 2366 while (!has_aborted() && _cm->mark_stack_size() > target_size) { 2367 if (get_entries_from_global_stack()) { 2368 drain_local_queue(partially); 2369 } 2370 } 2371 } else { 2372 while (!has_aborted() && get_entries_from_global_stack()) { 2373 drain_local_queue(partially); 2374 } 2375 } 2376 } 2377 2378 // SATB Queue has several assumptions on whether to call the par or 2379 // non-par versions of the methods. this is why some of the code is 2380 // replicated. We should really get rid of the single-threaded version 2381 // of the code to simplify things. 2382 void G1CMTask::drain_satb_buffers() { 2383 if (has_aborted()) { 2384 return; 2385 } 2386 2387 // We set this so that the regular clock knows that we're in the 2388 // middle of draining buffers and doesn't set the abort flag when it 2389 // notices that SATB buffers are available for draining. It'd be 2390 // very counter productive if it did that. :-) 2391 _draining_satb_buffers = true; 2392 2393 G1CMSATBBufferClosure satb_cl(this, _g1h); 2394 SATBMarkQueueSet& satb_mq_set = G1BarrierSet::satb_mark_queue_set(); 2395 2396 // This keeps claiming and applying the closure to completed buffers 2397 // until we run out of buffers or we need to abort. 2398 while (!has_aborted() && 2399 satb_mq_set.apply_closure_to_completed_buffer(&satb_cl)) { 2400 abort_marking_if_regular_check_fail(); 2401 } 2402 2403 _draining_satb_buffers = false; 2404 2405 assert(has_aborted() || 2406 _cm->concurrent() || 2407 satb_mq_set.completed_buffers_num() == 0, "invariant"); 2408 2409 // again, this was a potentially expensive operation, decrease the 2410 // limits to get the regular clock call early 2411 decrease_limits(); 2412 } 2413 2414 void G1CMTask::clear_mark_stats_cache(uint region_idx) { 2415 _mark_stats_cache.reset(region_idx); 2416 } 2417 2418 Pair<size_t, size_t> G1CMTask::flush_mark_stats_cache() { 2419 return _mark_stats_cache.evict_all(); 2420 } 2421 2422 void G1CMTask::print_stats() { 2423 log_debug(gc, stats)("Marking Stats, task = %u, calls = %u", _worker_id, _calls); 2424 log_debug(gc, stats)(" Elapsed time = %1.2lfms, Termination time = %1.2lfms", 2425 _elapsed_time_ms, _termination_time_ms); 2426 log_debug(gc, stats)(" Step Times (cum): num = %d, avg = %1.2lfms, sd = %1.2lfms max = %1.2lfms, total = %1.2lfms", 2427 _step_times_ms.num(), 2428 _step_times_ms.avg(), 2429 _step_times_ms.sd(), 2430 _step_times_ms.maximum(), 2431 _step_times_ms.sum()); 2432 size_t const hits = _mark_stats_cache.hits(); 2433 size_t const misses = _mark_stats_cache.misses(); 2434 log_debug(gc, stats)(" Mark Stats Cache: hits " SIZE_FORMAT " misses " SIZE_FORMAT " ratio %.3f", 2435 hits, misses, percent_of(hits, hits + misses)); 2436 } 2437 2438 bool G1ConcurrentMark::try_stealing(uint worker_id, G1TaskQueueEntry& task_entry) { 2439 return _task_queues->steal(worker_id, task_entry); 2440 } 2441 2442 /***************************************************************************** 2443 2444 The do_marking_step(time_target_ms, ...) method is the building 2445 block of the parallel marking framework. It can be called in parallel 2446 with other invocations of do_marking_step() on different tasks 2447 (but only one per task, obviously) and concurrently with the 2448 mutator threads, or during remark, hence it eliminates the need 2449 for two versions of the code. When called during remark, it will 2450 pick up from where the task left off during the concurrent marking 2451 phase. Interestingly, tasks are also claimable during evacuation 2452 pauses too, since do_marking_step() ensures that it aborts before 2453 it needs to yield. 2454 2455 The data structures that it uses to do marking work are the 2456 following: 2457 2458 (1) Marking Bitmap. If there are gray objects that appear only 2459 on the bitmap (this happens either when dealing with an overflow 2460 or when the initial marking phase has simply marked the roots 2461 and didn't push them on the stack), then tasks claim heap 2462 regions whose bitmap they then scan to find gray objects. A 2463 global finger indicates where the end of the last claimed region 2464 is. A local finger indicates how far into the region a task has 2465 scanned. The two fingers are used to determine how to gray an 2466 object (i.e. whether simply marking it is OK, as it will be 2467 visited by a task in the future, or whether it needs to be also 2468 pushed on a stack). 2469 2470 (2) Local Queue. The local queue of the task which is accessed 2471 reasonably efficiently by the task. Other tasks can steal from 2472 it when they run out of work. Throughout the marking phase, a 2473 task attempts to keep its local queue short but not totally 2474 empty, so that entries are available for stealing by other 2475 tasks. Only when there is no more work, a task will totally 2476 drain its local queue. 2477 2478 (3) Global Mark Stack. This handles local queue overflow. During 2479 marking only sets of entries are moved between it and the local 2480 queues, as access to it requires a mutex and more fine-grain 2481 interaction with it which might cause contention. If it 2482 overflows, then the marking phase should restart and iterate 2483 over the bitmap to identify gray objects. Throughout the marking 2484 phase, tasks attempt to keep the global mark stack at a small 2485 length but not totally empty, so that entries are available for 2486 popping by other tasks. Only when there is no more work, tasks 2487 will totally drain the global mark stack. 2488 2489 (4) SATB Buffer Queue. This is where completed SATB buffers are 2490 made available. Buffers are regularly removed from this queue 2491 and scanned for roots, so that the queue doesn't get too 2492 long. During remark, all completed buffers are processed, as 2493 well as the filled in parts of any uncompleted buffers. 2494 2495 The do_marking_step() method tries to abort when the time target 2496 has been reached. There are a few other cases when the 2497 do_marking_step() method also aborts: 2498 2499 (1) When the marking phase has been aborted (after a Full GC). 2500 2501 (2) When a global overflow (on the global stack) has been 2502 triggered. Before the task aborts, it will actually sync up with 2503 the other tasks to ensure that all the marking data structures 2504 (local queues, stacks, fingers etc.) are re-initialized so that 2505 when do_marking_step() completes, the marking phase can 2506 immediately restart. 2507 2508 (3) When enough completed SATB buffers are available. The 2509 do_marking_step() method only tries to drain SATB buffers right 2510 at the beginning. So, if enough buffers are available, the 2511 marking step aborts and the SATB buffers are processed at 2512 the beginning of the next invocation. 2513 2514 (4) To yield. when we have to yield then we abort and yield 2515 right at the end of do_marking_step(). This saves us from a lot 2516 of hassle as, by yielding we might allow a Full GC. If this 2517 happens then objects will be compacted underneath our feet, the 2518 heap might shrink, etc. We save checking for this by just 2519 aborting and doing the yield right at the end. 2520 2521 From the above it follows that the do_marking_step() method should 2522 be called in a loop (or, otherwise, regularly) until it completes. 2523 2524 If a marking step completes without its has_aborted() flag being 2525 true, it means it has completed the current marking phase (and 2526 also all other marking tasks have done so and have all synced up). 2527 2528 A method called regular_clock_call() is invoked "regularly" (in 2529 sub ms intervals) throughout marking. It is this clock method that 2530 checks all the abort conditions which were mentioned above and 2531 decides when the task should abort. A work-based scheme is used to 2532 trigger this clock method: when the number of object words the 2533 marking phase has scanned or the number of references the marking 2534 phase has visited reach a given limit. Additional invocations to 2535 the method clock have been planted in a few other strategic places 2536 too. The initial reason for the clock method was to avoid calling 2537 vtime too regularly, as it is quite expensive. So, once it was in 2538 place, it was natural to piggy-back all the other conditions on it 2539 too and not constantly check them throughout the code. 2540 2541 If do_termination is true then do_marking_step will enter its 2542 termination protocol. 2543 2544 The value of is_serial must be true when do_marking_step is being 2545 called serially (i.e. by the VMThread) and do_marking_step should 2546 skip any synchronization in the termination and overflow code. 2547 Examples include the serial remark code and the serial reference 2548 processing closures. 2549 2550 The value of is_serial must be false when do_marking_step is 2551 being called by any of the worker threads in a work gang. 2552 Examples include the concurrent marking code (CMMarkingTask), 2553 the MT remark code, and the MT reference processing closures. 2554 2555 *****************************************************************************/ 2556 2557 void G1CMTask::do_marking_step(double time_target_ms, 2558 bool do_termination, 2559 bool is_serial) { 2560 assert(time_target_ms >= 1.0, "minimum granularity is 1ms"); 2561 2562 _start_time_ms = os::elapsedVTime() * 1000.0; 2563 2564 // If do_stealing is true then do_marking_step will attempt to 2565 // steal work from the other G1CMTasks. It only makes sense to 2566 // enable stealing when the termination protocol is enabled 2567 // and do_marking_step() is not being called serially. 2568 bool do_stealing = do_termination && !is_serial; 2569 2570 double diff_prediction_ms = _g1h->g1_policy()->predictor().get_new_prediction(&_marking_step_diffs_ms); 2571 _time_target_ms = time_target_ms - diff_prediction_ms; 2572 2573 // set up the variables that are used in the work-based scheme to 2574 // call the regular clock method 2575 _words_scanned = 0; 2576 _refs_reached = 0; 2577 recalculate_limits(); 2578 2579 // clear all flags 2580 clear_has_aborted(); 2581 _has_timed_out = false; 2582 _draining_satb_buffers = false; 2583 2584 ++_calls; 2585 2586 // Set up the bitmap and oop closures. Anything that uses them is 2587 // eventually called from this method, so it is OK to allocate these 2588 // statically. 2589 G1CMBitMapClosure bitmap_closure(this, _cm); 2590 G1CMOopClosure cm_oop_closure(_g1h, this); 2591 set_cm_oop_closure(&cm_oop_closure); 2592 2593 if (_cm->has_overflown()) { 2594 // This can happen if the mark stack overflows during a GC pause 2595 // and this task, after a yield point, restarts. We have to abort 2596 // as we need to get into the overflow protocol which happens 2597 // right at the end of this task. 2598 set_has_aborted(); 2599 } 2600 2601 // First drain any available SATB buffers. After this, we will not 2602 // look at SATB buffers before the next invocation of this method. 2603 // If enough completed SATB buffers are queued up, the regular clock 2604 // will abort this task so that it restarts. 2605 drain_satb_buffers(); 2606 // ...then partially drain the local queue and the global stack 2607 drain_local_queue(true); 2608 drain_global_stack(true); 2609 2610 do { 2611 if (!has_aborted() && _curr_region != NULL) { 2612 // This means that we're already holding on to a region. 2613 assert(_finger != NULL, "if region is not NULL, then the finger " 2614 "should not be NULL either"); 2615 2616 // We might have restarted this task after an evacuation pause 2617 // which might have evacuated the region we're holding on to 2618 // underneath our feet. Let's read its limit again to make sure 2619 // that we do not iterate over a region of the heap that 2620 // contains garbage (update_region_limit() will also move 2621 // _finger to the start of the region if it is found empty). 2622 update_region_limit(); 2623 // We will start from _finger not from the start of the region, 2624 // as we might be restarting this task after aborting half-way 2625 // through scanning this region. In this case, _finger points to 2626 // the address where we last found a marked object. If this is a 2627 // fresh region, _finger points to start(). 2628 MemRegion mr = MemRegion(_finger, _region_limit); 2629 2630 assert(!_curr_region->is_humongous() || mr.start() == _curr_region->bottom(), 2631 "humongous regions should go around loop once only"); 2632 2633 // Some special cases: 2634 // If the memory region is empty, we can just give up the region. 2635 // If the current region is humongous then we only need to check 2636 // the bitmap for the bit associated with the start of the object, 2637 // scan the object if it's live, and give up the region. 2638 // Otherwise, let's iterate over the bitmap of the part of the region 2639 // that is left. 2640 // If the iteration is successful, give up the region. 2641 if (mr.is_empty()) { 2642 giveup_current_region(); 2643 abort_marking_if_regular_check_fail(); 2644 } else if (_curr_region->is_humongous() && mr.start() == _curr_region->bottom()) { 2645 if (_next_mark_bitmap->is_marked(mr.start())) { 2646 // The object is marked - apply the closure 2647 bitmap_closure.do_addr(mr.start()); 2648 } 2649 // Even if this task aborted while scanning the humongous object 2650 // we can (and should) give up the current region. 2651 giveup_current_region(); 2652 abort_marking_if_regular_check_fail(); 2653 } else if (_next_mark_bitmap->iterate(&bitmap_closure, mr)) { 2654 giveup_current_region(); 2655 abort_marking_if_regular_check_fail(); 2656 } else { 2657 assert(has_aborted(), "currently the only way to do so"); 2658 // The only way to abort the bitmap iteration is to return 2659 // false from the do_bit() method. However, inside the 2660 // do_bit() method we move the _finger to point to the 2661 // object currently being looked at. So, if we bail out, we 2662 // have definitely set _finger to something non-null. 2663 assert(_finger != NULL, "invariant"); 2664 2665 // Region iteration was actually aborted. So now _finger 2666 // points to the address of the object we last scanned. If we 2667 // leave it there, when we restart this task, we will rescan 2668 // the object. It is easy to avoid this. We move the finger by 2669 // enough to point to the next possible object header. 2670 assert(_finger < _region_limit, "invariant"); 2671 HeapWord* const new_finger = _finger + ((oop)_finger)->size(); 2672 // Check if bitmap iteration was aborted while scanning the last object 2673 if (new_finger >= _region_limit) { 2674 giveup_current_region(); 2675 } else { 2676 move_finger_to(new_finger); 2677 } 2678 } 2679 } 2680 // At this point we have either completed iterating over the 2681 // region we were holding on to, or we have aborted. 2682 2683 // We then partially drain the local queue and the global stack. 2684 // (Do we really need this?) 2685 drain_local_queue(true); 2686 drain_global_stack(true); 2687 2688 // Read the note on the claim_region() method on why it might 2689 // return NULL with potentially more regions available for 2690 // claiming and why we have to check out_of_regions() to determine 2691 // whether we're done or not. 2692 while (!has_aborted() && _curr_region == NULL && !_cm->out_of_regions()) { 2693 // We are going to try to claim a new region. We should have 2694 // given up on the previous one. 2695 // Separated the asserts so that we know which one fires. 2696 assert(_curr_region == NULL, "invariant"); 2697 assert(_finger == NULL, "invariant"); 2698 assert(_region_limit == NULL, "invariant"); 2699 HeapRegion* claimed_region = _cm->claim_region(_worker_id); 2700 if (claimed_region != NULL) { 2701 // Yes, we managed to claim one 2702 setup_for_region(claimed_region); 2703 assert(_curr_region == claimed_region, "invariant"); 2704 } 2705 // It is important to call the regular clock here. It might take 2706 // a while to claim a region if, for example, we hit a large 2707 // block of empty regions. So we need to call the regular clock 2708 // method once round the loop to make sure it's called 2709 // frequently enough. 2710 abort_marking_if_regular_check_fail(); 2711 } 2712 2713 if (!has_aborted() && _curr_region == NULL) { 2714 assert(_cm->out_of_regions(), 2715 "at this point we should be out of regions"); 2716 } 2717 } while ( _curr_region != NULL && !has_aborted()); 2718 2719 if (!has_aborted()) { 2720 // We cannot check whether the global stack is empty, since other 2721 // tasks might be pushing objects to it concurrently. 2722 assert(_cm->out_of_regions(), 2723 "at this point we should be out of regions"); 2724 // Try to reduce the number of available SATB buffers so that 2725 // remark has less work to do. 2726 drain_satb_buffers(); 2727 } 2728 2729 // Since we've done everything else, we can now totally drain the 2730 // local queue and global stack. 2731 drain_local_queue(false); 2732 drain_global_stack(false); 2733 2734 // Attempt at work stealing from other task's queues. 2735 if (do_stealing && !has_aborted()) { 2736 // We have not aborted. This means that we have finished all that 2737 // we could. Let's try to do some stealing... 2738 2739 // We cannot check whether the global stack is empty, since other 2740 // tasks might be pushing objects to it concurrently. 2741 assert(_cm->out_of_regions() && _task_queue->size() == 0, 2742 "only way to reach here"); 2743 while (!has_aborted()) { 2744 G1TaskQueueEntry entry; 2745 if (_cm->try_stealing(_worker_id, entry)) { 2746 scan_task_entry(entry); 2747 2748 // And since we're towards the end, let's totally drain the 2749 // local queue and global stack. 2750 drain_local_queue(false); 2751 drain_global_stack(false); 2752 } else { 2753 break; 2754 } 2755 } 2756 } 2757 2758 // We still haven't aborted. Now, let's try to get into the 2759 // termination protocol. 2760 if (do_termination && !has_aborted()) { 2761 // We cannot check whether the global stack is empty, since other 2762 // tasks might be concurrently pushing objects on it. 2763 // Separated the asserts so that we know which one fires. 2764 assert(_cm->out_of_regions(), "only way to reach here"); 2765 assert(_task_queue->size() == 0, "only way to reach here"); 2766 _termination_start_time_ms = os::elapsedVTime() * 1000.0; 2767 2768 // The G1CMTask class also extends the TerminatorTerminator class, 2769 // hence its should_exit_termination() method will also decide 2770 // whether to exit the termination protocol or not. 2771 bool finished = (is_serial || 2772 _cm->terminator()->offer_termination(this)); 2773 double termination_end_time_ms = os::elapsedVTime() * 1000.0; 2774 _termination_time_ms += 2775 termination_end_time_ms - _termination_start_time_ms; 2776 2777 if (finished) { 2778 // We're all done. 2779 2780 // We can now guarantee that the global stack is empty, since 2781 // all other tasks have finished. We separated the guarantees so 2782 // that, if a condition is false, we can immediately find out 2783 // which one. 2784 guarantee(_cm->out_of_regions(), "only way to reach here"); 2785 guarantee(_cm->mark_stack_empty(), "only way to reach here"); 2786 guarantee(_task_queue->size() == 0, "only way to reach here"); 2787 guarantee(!_cm->has_overflown(), "only way to reach here"); 2788 guarantee(!has_aborted(), "should never happen if termination has completed"); 2789 } else { 2790 // Apparently there's more work to do. Let's abort this task. It 2791 // will restart it and we can hopefully find more things to do. 2792 set_has_aborted(); 2793 } 2794 } 2795 2796 // Mainly for debugging purposes to make sure that a pointer to the 2797 // closure which was statically allocated in this frame doesn't 2798 // escape it by accident. 2799 set_cm_oop_closure(NULL); 2800 double end_time_ms = os::elapsedVTime() * 1000.0; 2801 double elapsed_time_ms = end_time_ms - _start_time_ms; 2802 // Update the step history. 2803 _step_times_ms.add(elapsed_time_ms); 2804 2805 if (has_aborted()) { 2806 // The task was aborted for some reason. 2807 if (_has_timed_out) { 2808 double diff_ms = elapsed_time_ms - _time_target_ms; 2809 // Keep statistics of how well we did with respect to hitting 2810 // our target only if we actually timed out (if we aborted for 2811 // other reasons, then the results might get skewed). 2812 _marking_step_diffs_ms.add(diff_ms); 2813 } 2814 2815 if (_cm->has_overflown()) { 2816 // This is the interesting one. We aborted because a global 2817 // overflow was raised. This means we have to restart the 2818 // marking phase and start iterating over regions. However, in 2819 // order to do this we have to make sure that all tasks stop 2820 // what they are doing and re-initialize in a safe manner. We 2821 // will achieve this with the use of two barrier sync points. 2822 2823 if (!is_serial) { 2824 // We only need to enter the sync barrier if being called 2825 // from a parallel context 2826 _cm->enter_first_sync_barrier(_worker_id); 2827 2828 // When we exit this sync barrier we know that all tasks have 2829 // stopped doing marking work. So, it's now safe to 2830 // re-initialize our data structures. 2831 } 2832 2833 clear_region_fields(); 2834 flush_mark_stats_cache(); 2835 2836 if (!is_serial) { 2837 // If we're executing the concurrent phase of marking, reset the marking 2838 // state; otherwise the marking state is reset after reference processing, 2839 // during the remark pause. 2840 // If we reset here as a result of an overflow during the remark we will 2841 // see assertion failures from any subsequent set_concurrency_and_phase() 2842 // calls. 2843 if (_cm->concurrent() && _worker_id == 0) { 2844 // Worker 0 is responsible for clearing the global data structures because 2845 // of an overflow. During STW we should not clear the overflow flag (in 2846 // G1ConcurrentMark::reset_marking_state()) since we rely on it being true when we exit 2847 // method to abort the pause and restart concurrent marking. 2848 _cm->reset_marking_for_restart(); 2849 2850 log_info(gc, marking)("Concurrent Mark reset for overflow"); 2851 } 2852 2853 // ...and enter the second barrier. 2854 _cm->enter_second_sync_barrier(_worker_id); 2855 } 2856 // At this point, if we're during the concurrent phase of 2857 // marking, everything has been re-initialized and we're 2858 // ready to restart. 2859 } 2860 } 2861 } 2862 2863 G1CMTask::G1CMTask(uint worker_id, 2864 G1ConcurrentMark* cm, 2865 G1CMTaskQueue* task_queue, 2866 G1RegionMarkStats* mark_stats, 2867 uint max_regions) : 2868 _objArray_processor(this), 2869 _worker_id(worker_id), 2870 _g1h(G1CollectedHeap::heap()), 2871 _cm(cm), 2872 _next_mark_bitmap(NULL), 2873 _task_queue(task_queue), 2874 _mark_stats_cache(mark_stats, max_regions, RegionMarkStatsCacheSize), 2875 _calls(0), 2876 _time_target_ms(0.0), 2877 _start_time_ms(0.0), 2878 _cm_oop_closure(NULL), 2879 _curr_region(NULL), 2880 _finger(NULL), 2881 _region_limit(NULL), 2882 _words_scanned(0), 2883 _words_scanned_limit(0), 2884 _real_words_scanned_limit(0), 2885 _refs_reached(0), 2886 _refs_reached_limit(0), 2887 _real_refs_reached_limit(0), 2888 _has_aborted(false), 2889 _has_timed_out(false), 2890 _draining_satb_buffers(false), 2891 _step_times_ms(), 2892 _elapsed_time_ms(0.0), 2893 _termination_time_ms(0.0), 2894 _termination_start_time_ms(0.0), 2895 _marking_step_diffs_ms() 2896 { 2897 guarantee(task_queue != NULL, "invariant"); 2898 2899 _marking_step_diffs_ms.add(0.5); 2900 } 2901 2902 // These are formatting macros that are used below to ensure 2903 // consistent formatting. The *_H_* versions are used to format the 2904 // header for a particular value and they should be kept consistent 2905 // with the corresponding macro. Also note that most of the macros add 2906 // the necessary white space (as a prefix) which makes them a bit 2907 // easier to compose. 2908 2909 // All the output lines are prefixed with this string to be able to 2910 // identify them easily in a large log file. 2911 #define G1PPRL_LINE_PREFIX "###" 2912 2913 #define G1PPRL_ADDR_BASE_FORMAT " " PTR_FORMAT "-" PTR_FORMAT 2914 #ifdef _LP64 2915 #define G1PPRL_ADDR_BASE_H_FORMAT " %37s" 2916 #else // _LP64 2917 #define G1PPRL_ADDR_BASE_H_FORMAT " %21s" 2918 #endif // _LP64 2919 2920 // For per-region info 2921 #define G1PPRL_TYPE_FORMAT " %-4s" 2922 #define G1PPRL_TYPE_H_FORMAT " %4s" 2923 #define G1PPRL_STATE_FORMAT " %-5s" 2924 #define G1PPRL_STATE_H_FORMAT " %5s" 2925 #define G1PPRL_BYTE_FORMAT " " SIZE_FORMAT_W(9) 2926 #define G1PPRL_BYTE_H_FORMAT " %9s" 2927 #define G1PPRL_DOUBLE_FORMAT " %14.1f" 2928 #define G1PPRL_DOUBLE_H_FORMAT " %14s" 2929 2930 // For summary info 2931 #define G1PPRL_SUM_ADDR_FORMAT(tag) " " tag ":" G1PPRL_ADDR_BASE_FORMAT 2932 #define G1PPRL_SUM_BYTE_FORMAT(tag) " " tag ": " SIZE_FORMAT 2933 #define G1PPRL_SUM_MB_FORMAT(tag) " " tag ": %1.2f MB" 2934 #define G1PPRL_SUM_MB_PERC_FORMAT(tag) G1PPRL_SUM_MB_FORMAT(tag) " / %1.2f %%" 2935 2936 G1PrintRegionLivenessInfoClosure::G1PrintRegionLivenessInfoClosure(const char* phase_name) : 2937 _total_used_bytes(0), _total_capacity_bytes(0), 2938 _total_prev_live_bytes(0), _total_next_live_bytes(0), 2939 _total_remset_bytes(0), _total_strong_code_roots_bytes(0) 2940 { 2941 if (!log_is_enabled(Trace, gc, liveness)) { 2942 return; 2943 } 2944 2945 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 2946 MemRegion g1_reserved = g1h->g1_reserved(); 2947 double now = os::elapsedTime(); 2948 2949 // Print the header of the output. 2950 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX" PHASE %s @ %1.3f", phase_name, now); 2951 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX" HEAP" 2952 G1PPRL_SUM_ADDR_FORMAT("reserved") 2953 G1PPRL_SUM_BYTE_FORMAT("region-size"), 2954 p2i(g1_reserved.start()), p2i(g1_reserved.end()), 2955 HeapRegion::GrainBytes); 2956 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX); 2957 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX 2958 G1PPRL_TYPE_H_FORMAT 2959 G1PPRL_ADDR_BASE_H_FORMAT 2960 G1PPRL_BYTE_H_FORMAT 2961 G1PPRL_BYTE_H_FORMAT 2962 G1PPRL_BYTE_H_FORMAT 2963 G1PPRL_DOUBLE_H_FORMAT 2964 G1PPRL_BYTE_H_FORMAT 2965 G1PPRL_STATE_H_FORMAT 2966 G1PPRL_BYTE_H_FORMAT, 2967 "type", "address-range", 2968 "used", "prev-live", "next-live", "gc-eff", 2969 "remset", "state", "code-roots"); 2970 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX 2971 G1PPRL_TYPE_H_FORMAT 2972 G1PPRL_ADDR_BASE_H_FORMAT 2973 G1PPRL_BYTE_H_FORMAT 2974 G1PPRL_BYTE_H_FORMAT 2975 G1PPRL_BYTE_H_FORMAT 2976 G1PPRL_DOUBLE_H_FORMAT 2977 G1PPRL_BYTE_H_FORMAT 2978 G1PPRL_STATE_H_FORMAT 2979 G1PPRL_BYTE_H_FORMAT, 2980 "", "", 2981 "(bytes)", "(bytes)", "(bytes)", "(bytes/ms)", 2982 "(bytes)", "", "(bytes)"); 2983 } 2984 2985 bool G1PrintRegionLivenessInfoClosure::do_heap_region(HeapRegion* r) { 2986 if (!log_is_enabled(Trace, gc, liveness)) { 2987 return false; 2988 } 2989 2990 const char* type = r->get_type_str(); 2991 HeapWord* bottom = r->bottom(); 2992 HeapWord* end = r->end(); 2993 size_t capacity_bytes = r->capacity(); 2994 size_t used_bytes = r->used(); 2995 size_t prev_live_bytes = r->live_bytes(); 2996 size_t next_live_bytes = r->next_live_bytes(); 2997 double gc_eff = r->gc_efficiency(); 2998 size_t remset_bytes = r->rem_set()->mem_size(); 2999 size_t strong_code_roots_bytes = r->rem_set()->strong_code_roots_mem_size(); 3000 const char* remset_type = r->rem_set()->get_short_state_str(); 3001 3002 _total_used_bytes += used_bytes; 3003 _total_capacity_bytes += capacity_bytes; 3004 _total_prev_live_bytes += prev_live_bytes; 3005 _total_next_live_bytes += next_live_bytes; 3006 _total_remset_bytes += remset_bytes; 3007 _total_strong_code_roots_bytes += strong_code_roots_bytes; 3008 3009 // Print a line for this particular region. 3010 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX 3011 G1PPRL_TYPE_FORMAT 3012 G1PPRL_ADDR_BASE_FORMAT 3013 G1PPRL_BYTE_FORMAT 3014 G1PPRL_BYTE_FORMAT 3015 G1PPRL_BYTE_FORMAT 3016 G1PPRL_DOUBLE_FORMAT 3017 G1PPRL_BYTE_FORMAT 3018 G1PPRL_STATE_FORMAT 3019 G1PPRL_BYTE_FORMAT, 3020 type, p2i(bottom), p2i(end), 3021 used_bytes, prev_live_bytes, next_live_bytes, gc_eff, 3022 remset_bytes, remset_type, strong_code_roots_bytes); 3023 3024 return false; 3025 } 3026 3027 G1PrintRegionLivenessInfoClosure::~G1PrintRegionLivenessInfoClosure() { 3028 if (!log_is_enabled(Trace, gc, liveness)) { 3029 return; 3030 } 3031 3032 // add static memory usages to remembered set sizes 3033 _total_remset_bytes += HeapRegionRemSet::fl_mem_size() + HeapRegionRemSet::static_mem_size(); 3034 // Print the footer of the output. 3035 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX); 3036 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX 3037 " SUMMARY" 3038 G1PPRL_SUM_MB_FORMAT("capacity") 3039 G1PPRL_SUM_MB_PERC_FORMAT("used") 3040 G1PPRL_SUM_MB_PERC_FORMAT("prev-live") 3041 G1PPRL_SUM_MB_PERC_FORMAT("next-live") 3042 G1PPRL_SUM_MB_FORMAT("remset") 3043 G1PPRL_SUM_MB_FORMAT("code-roots"), 3044 bytes_to_mb(_total_capacity_bytes), 3045 bytes_to_mb(_total_used_bytes), 3046 percent_of(_total_used_bytes, _total_capacity_bytes), 3047 bytes_to_mb(_total_prev_live_bytes), 3048 percent_of(_total_prev_live_bytes, _total_capacity_bytes), 3049 bytes_to_mb(_total_next_live_bytes), 3050 percent_of(_total_next_live_bytes, _total_capacity_bytes), 3051 bytes_to_mb(_total_remset_bytes), 3052 bytes_to_mb(_total_strong_code_roots_bytes)); 3053 }