1 /* 2 * Copyright (c) 2001, 2023, 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 "classfile/metadataOnStackMark.hpp" 28 #include "classfile/stringTable.hpp" 29 #include "code/codeCache.hpp" 30 #include "code/icBuffer.hpp" 31 #include "compiler/oopMap.hpp" 32 #include "gc/g1/g1Allocator.inline.hpp" 33 #include "gc/g1/g1Arguments.hpp" 34 #include "gc/g1/g1BarrierSet.hpp" 35 #include "gc/g1/g1BatchedTask.hpp" 36 #include "gc/g1/g1CollectedHeap.inline.hpp" 37 #include "gc/g1/g1CollectionSet.hpp" 38 #include "gc/g1/g1CollectionSetCandidates.hpp" 39 #include "gc/g1/g1CollectorState.hpp" 40 #include "gc/g1/g1ConcurrentRefine.hpp" 41 #include "gc/g1/g1ConcurrentRefineThread.hpp" 42 #include "gc/g1/g1ConcurrentMarkThread.inline.hpp" 43 #include "gc/g1/g1DirtyCardQueue.hpp" 44 #include "gc/g1/g1EvacStats.inline.hpp" 45 #include "gc/g1/g1FullCollector.hpp" 46 #include "gc/g1/g1GCCounters.hpp" 47 #include "gc/g1/g1GCParPhaseTimesTracker.hpp" 48 #include "gc/g1/g1GCPhaseTimes.hpp" 49 #include "gc/g1/g1GCPauseType.hpp" 50 #include "gc/g1/g1HeapSizingPolicy.hpp" 51 #include "gc/g1/g1HeapTransition.hpp" 52 #include "gc/g1/g1HeapVerifier.hpp" 53 #include "gc/g1/g1InitLogger.hpp" 54 #include "gc/g1/g1MemoryPool.hpp" 55 #include "gc/g1/g1MonotonicArenaFreeMemoryTask.hpp" 56 #include "gc/g1/g1OopClosures.inline.hpp" 57 #include "gc/g1/g1ParallelCleaning.hpp" 58 #include "gc/g1/g1ParScanThreadState.inline.hpp" 59 #include "gc/g1/g1PeriodicGCTask.hpp" 60 #include "gc/g1/g1Policy.hpp" 61 #include "gc/g1/g1RedirtyCardsQueue.hpp" 62 #include "gc/g1/g1RegionToSpaceMapper.hpp" 63 #include "gc/g1/g1RemSet.hpp" 64 #include "gc/g1/g1RootClosures.hpp" 65 #include "gc/g1/g1RootProcessor.hpp" 66 #include "gc/g1/g1SATBMarkQueueSet.hpp" 67 #include "gc/g1/g1ServiceThread.hpp" 68 #include "gc/g1/g1ThreadLocalData.hpp" 69 #include "gc/g1/g1Trace.hpp" 70 #include "gc/g1/g1UncommitRegionTask.hpp" 71 #include "gc/g1/g1VMOperations.hpp" 72 #include "gc/g1/g1YoungCollector.hpp" 73 #include "gc/g1/g1YoungGCEvacFailureInjector.hpp" 74 #include "gc/g1/heapRegion.inline.hpp" 75 #include "gc/g1/heapRegionRemSet.inline.hpp" 76 #include "gc/g1/heapRegionSet.inline.hpp" 77 #include "gc/shared/concurrentGCBreakpoints.hpp" 78 #include "gc/shared/gcBehaviours.hpp" 79 #include "gc/shared/gcForwarding.hpp" 80 #include "gc/shared/gcHeapSummary.hpp" 81 #include "gc/shared/gcId.hpp" 82 #include "gc/shared/gcLocker.inline.hpp" 83 #include "gc/shared/gcTimer.hpp" 84 #include "gc/shared/gcTraceTime.inline.hpp" 85 #include "gc/shared/generationSpec.hpp" 86 #include "gc/shared/isGCActiveMark.hpp" 87 #include "gc/shared/locationPrinter.inline.hpp" 88 #include "gc/shared/oopStorageParState.hpp" 89 #include "gc/shared/preservedMarks.inline.hpp" 90 #include "gc/shared/referenceProcessor.inline.hpp" 91 #include "gc/shared/suspendibleThreadSet.hpp" 92 #include "gc/shared/taskqueue.inline.hpp" 93 #include "gc/shared/taskTerminator.hpp" 94 #include "gc/shared/tlab_globals.hpp" 95 #include "gc/shared/workerPolicy.hpp" 96 #include "gc/shared/weakProcessor.inline.hpp" 97 #include "logging/log.hpp" 98 #include "memory/allocation.hpp" 99 #include "memory/heapInspection.hpp" 100 #include "memory/iterator.hpp" 101 #include "memory/metaspaceUtils.hpp" 102 #include "memory/resourceArea.hpp" 103 #include "memory/universe.hpp" 104 #include "oops/access.inline.hpp" 105 #include "oops/compressedOops.inline.hpp" 106 #include "oops/oop.inline.hpp" 107 #include "runtime/atomic.hpp" 108 #include "runtime/handles.inline.hpp" 109 #include "runtime/init.hpp" 110 #include "runtime/java.hpp" 111 #include "runtime/orderAccess.hpp" 112 #include "runtime/threadSMR.hpp" 113 #include "runtime/vmThread.hpp" 114 #include "utilities/align.hpp" 115 #include "utilities/autoRestore.hpp" 116 #include "utilities/bitMap.inline.hpp" 117 #include "utilities/globalDefinitions.hpp" 118 #include "utilities/stack.inline.hpp" 119 120 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0; 121 122 // INVARIANTS/NOTES 123 // 124 // All allocation activity covered by the G1CollectedHeap interface is 125 // serialized by acquiring the HeapLock. This happens in mem_allocate 126 // and allocate_new_tlab, which are the "entry" points to the 127 // allocation code from the rest of the JVM. (Note that this does not 128 // apply to TLAB allocation, which is not part of this interface: it 129 // is done by clients of this interface.) 130 131 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) { 132 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions); 133 } 134 135 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) { 136 // The from card cache is not the memory that is actually committed. So we cannot 137 // take advantage of the zero_filled parameter. 138 reset_from_card_cache(start_idx, num_regions); 139 } 140 141 void G1CollectedHeap::run_batch_task(G1BatchedTask* cl) { 142 uint num_workers = MAX2(1u, MIN2(cl->num_workers_estimate(), workers()->active_workers())); 143 cl->set_max_workers(num_workers); 144 workers()->run_task(cl, num_workers); 145 } 146 147 uint G1CollectedHeap::get_chunks_per_region() { 148 uint log_region_size = HeapRegion::LogOfHRGrainBytes; 149 // Limit the expected input values to current known possible values of the 150 // (log) region size. Adjust as necessary after testing if changing the permissible 151 // values for region size. 152 assert(log_region_size >= 20 && log_region_size <= 29, 153 "expected value in [20,29], but got %u", log_region_size); 154 return 1u << (log_region_size / 2 - 4); 155 } 156 157 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index, 158 MemRegion mr) { 159 return new HeapRegion(hrs_index, bot(), mr, &_card_set_config); 160 } 161 162 // Private methods. 163 164 HeapRegion* G1CollectedHeap::new_region(size_t word_size, 165 HeapRegionType type, 166 bool do_expand, 167 uint node_index) { 168 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords, 169 "the only time we use this to allocate a humongous region is " 170 "when we are allocating a single humongous region"); 171 172 HeapRegion* res = _hrm.allocate_free_region(type, node_index); 173 174 if (res == nullptr && do_expand) { 175 // Currently, only attempts to allocate GC alloc regions set 176 // do_expand to true. So, we should only reach here during a 177 // safepoint. 178 assert(SafepointSynchronize::is_at_safepoint(), "invariant"); 179 180 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B", 181 word_size * HeapWordSize); 182 183 assert(word_size * HeapWordSize < HeapRegion::GrainBytes, 184 "This kind of expansion should never be more than one region. Size: " SIZE_FORMAT, 185 word_size * HeapWordSize); 186 if (expand_single_region(node_index)) { 187 // Given that expand_single_region() succeeded in expanding the heap, and we 188 // always expand the heap by an amount aligned to the heap 189 // region size, the free list should in theory not be empty. 190 // In either case allocate_free_region() will check for null. 191 res = _hrm.allocate_free_region(type, node_index); 192 } 193 } 194 return res; 195 } 196 197 void G1CollectedHeap::set_humongous_metadata(HeapRegion* first_hr, 198 uint num_regions, 199 size_t word_size, 200 bool update_remsets) { 201 // Calculate the new top of the humongous object. 202 HeapWord* obj_top = first_hr->bottom() + word_size; 203 // The word size sum of all the regions used 204 size_t word_size_sum = num_regions * HeapRegion::GrainWords; 205 assert(word_size <= word_size_sum, "sanity"); 206 207 // How many words memory we "waste" which cannot hold a filler object. 208 size_t words_not_fillable = 0; 209 210 // Pad out the unused tail of the last region with filler 211 // objects, for improved usage accounting. 212 213 // How many words can we use for filler objects. 214 size_t words_fillable = word_size_sum - word_size; 215 216 if (words_fillable >= G1CollectedHeap::min_fill_size()) { 217 G1CollectedHeap::fill_with_objects(obj_top, words_fillable); 218 } else { 219 // We have space to fill, but we cannot fit an object there. 220 words_not_fillable = words_fillable; 221 words_fillable = 0; 222 } 223 224 // We will set up the first region as "starts humongous". This 225 // will also update the BOT covering all the regions to reflect 226 // that there is a single object that starts at the bottom of the 227 // first region. 228 first_hr->hr_clear(false /* clear_space */); 229 first_hr->set_starts_humongous(obj_top, words_fillable); 230 231 if (update_remsets) { 232 _policy->remset_tracker()->update_at_allocate(first_hr); 233 } 234 235 // Indices of first and last regions in the series. 236 uint first = first_hr->hrm_index(); 237 uint last = first + num_regions - 1; 238 239 HeapRegion* hr = nullptr; 240 for (uint i = first + 1; i <= last; ++i) { 241 hr = region_at(i); 242 hr->hr_clear(false /* clear_space */); 243 hr->set_continues_humongous(first_hr); 244 if (update_remsets) { 245 _policy->remset_tracker()->update_at_allocate(hr); 246 } 247 } 248 249 // Up to this point no concurrent thread would have been able to 250 // do any scanning on any region in this series. All the top 251 // fields still point to bottom, so the intersection between 252 // [bottom,top] and [card_start,card_end] will be empty. Before we 253 // update the top fields, we'll do a storestore to make sure that 254 // no thread sees the update to top before the zeroing of the 255 // object header and the BOT initialization. 256 OrderAccess::storestore(); 257 258 // Now, we will update the top fields of the "continues humongous" 259 // regions except the last one. 260 for (uint i = first; i < last; ++i) { 261 hr = region_at(i); 262 hr->set_top(hr->end()); 263 } 264 265 hr = region_at(last); 266 // If we cannot fit a filler object, we must set top to the end 267 // of the humongous object, otherwise we cannot iterate the heap 268 // and the BOT will not be complete. 269 hr->set_top(hr->end() - words_not_fillable); 270 271 assert(hr->bottom() < obj_top && obj_top <= hr->end(), 272 "obj_top should be in last region"); 273 274 assert(words_not_fillable == 0 || 275 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(), 276 "Miscalculation in humongous allocation"); 277 } 278 279 HeapWord* 280 G1CollectedHeap::humongous_obj_allocate_initialize_regions(HeapRegion* first_hr, 281 uint num_regions, 282 size_t word_size) { 283 assert(first_hr != nullptr, "pre-condition"); 284 assert(is_humongous(word_size), "word_size should be humongous"); 285 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition"); 286 287 // Index of last region in the series. 288 uint first = first_hr->hrm_index(); 289 uint last = first + num_regions - 1; 290 291 // We need to initialize the region(s) we just discovered. This is 292 // a bit tricky given that it can happen concurrently with 293 // refinement threads refining cards on these regions and 294 // potentially wanting to refine the BOT as they are scanning 295 // those cards (this can happen shortly after a cleanup; see CR 296 // 6991377). So we have to set up the region(s) carefully and in 297 // a specific order. 298 299 // The passed in hr will be the "starts humongous" region. The header 300 // of the new object will be placed at the bottom of this region. 301 HeapWord* new_obj = first_hr->bottom(); 302 303 // First, we need to zero the header of the space that we will be 304 // allocating. When we update top further down, some refinement 305 // threads might try to scan the region. By zeroing the header we 306 // ensure that any thread that will try to scan the region will 307 // come across the zero klass word and bail out. 308 // 309 // NOTE: It would not have been correct to have used 310 // CollectedHeap::fill_with_object() and make the space look like 311 // an int array. The thread that is doing the allocation will 312 // later update the object header to a potentially different array 313 // type and, for a very short period of time, the klass and length 314 // fields will be inconsistent. This could cause a refinement 315 // thread to calculate the object size incorrectly. 316 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0); 317 318 // Next, update the metadata for the regions. 319 set_humongous_metadata(first_hr, num_regions, word_size, true); 320 321 HeapRegion* last_hr = region_at(last); 322 size_t used = byte_size(first_hr->bottom(), last_hr->top()); 323 324 increase_used(used); 325 326 for (uint i = first; i <= last; ++i) { 327 HeapRegion *hr = region_at(i); 328 _humongous_set.add(hr); 329 _hr_printer.alloc(hr); 330 } 331 332 return new_obj; 333 } 334 335 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) { 336 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size); 337 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords; 338 } 339 340 // If could fit into free regions w/o expansion, try. 341 // Otherwise, if can expand, do so. 342 // Otherwise, if using ex regions might help, try with ex given back. 343 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) { 344 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 345 346 _verifier->verify_region_sets_optional(); 347 348 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size); 349 350 // Policy: First try to allocate a humongous object in the free list. 351 HeapRegion* humongous_start = _hrm.allocate_humongous(obj_regions); 352 if (humongous_start == nullptr) { 353 // Policy: We could not find enough regions for the humongous object in the 354 // free list. Look through the heap to find a mix of free and uncommitted regions. 355 // If so, expand the heap and allocate the humongous object. 356 humongous_start = _hrm.expand_and_allocate_humongous(obj_regions); 357 if (humongous_start != nullptr) { 358 // We managed to find a region by expanding the heap. 359 log_debug(gc, ergo, heap)("Heap expansion (humongous allocation request). Allocation request: " SIZE_FORMAT "B", 360 word_size * HeapWordSize); 361 policy()->record_new_heap_size(num_regions()); 362 } else { 363 // Policy: Potentially trigger a defragmentation GC. 364 } 365 } 366 367 HeapWord* result = nullptr; 368 if (humongous_start != nullptr) { 369 result = humongous_obj_allocate_initialize_regions(humongous_start, obj_regions, word_size); 370 assert(result != nullptr, "it should always return a valid result"); 371 372 // A successful humongous object allocation changes the used space 373 // information of the old generation so we need to recalculate the 374 // sizes and update the jstat counters here. 375 monitoring_support()->update_sizes(); 376 } 377 378 _verifier->verify_region_sets_optional(); 379 380 return result; 381 } 382 383 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size, 384 size_t requested_size, 385 size_t* actual_size) { 386 assert_heap_not_locked_and_not_at_safepoint(); 387 assert(!is_humongous(requested_size), "we do not allow humongous TLABs"); 388 389 return attempt_allocation(min_size, requested_size, actual_size); 390 } 391 392 HeapWord* 393 G1CollectedHeap::mem_allocate(size_t word_size, 394 bool* gc_overhead_limit_was_exceeded) { 395 assert_heap_not_locked_and_not_at_safepoint(); 396 397 if (is_humongous(word_size)) { 398 return attempt_allocation_humongous(word_size); 399 } 400 size_t dummy = 0; 401 return attempt_allocation(word_size, word_size, &dummy); 402 } 403 404 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) { 405 ResourceMark rm; // For retrieving the thread names in log messages. 406 407 // Make sure you read the note in attempt_allocation_humongous(). 408 409 assert_heap_not_locked_and_not_at_safepoint(); 410 assert(!is_humongous(word_size), "attempt_allocation_slow() should not " 411 "be called for humongous allocation requests"); 412 413 // We should only get here after the first-level allocation attempt 414 // (attempt_allocation()) failed to allocate. 415 416 // We will loop until a) we manage to successfully perform the 417 // allocation or b) we successfully schedule a collection which 418 // fails to perform the allocation. b) is the only case when we'll 419 // return null. 420 HeapWord* result = nullptr; 421 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 422 bool should_try_gc; 423 uint gc_count_before; 424 425 { 426 MutexLocker x(Heap_lock); 427 428 // Now that we have the lock, we first retry the allocation in case another 429 // thread changed the region while we were waiting to acquire the lock. 430 result = _allocator->attempt_allocation_locked(word_size); 431 if (result != nullptr) { 432 return result; 433 } 434 435 // If the GCLocker is active and we are bound for a GC, try expanding young gen. 436 // This is different to when only GCLocker::needs_gc() is set: try to avoid 437 // waiting because the GCLocker is active to not wait too long. 438 if (GCLocker::is_active_and_needs_gc() && policy()->can_expand_young_list()) { 439 // No need for an ergo message here, can_expand_young_list() does this when 440 // it returns true. 441 result = _allocator->attempt_allocation_force(word_size); 442 if (result != nullptr) { 443 return result; 444 } 445 } 446 447 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until 448 // the GCLocker initiated GC has been performed and then retry. This includes 449 // the case when the GC Locker is not active but has not been performed. 450 should_try_gc = !GCLocker::needs_gc(); 451 // Read the GC count while still holding the Heap_lock. 452 gc_count_before = total_collections(); 453 } 454 455 if (should_try_gc) { 456 bool succeeded; 457 result = do_collection_pause(word_size, gc_count_before, &succeeded, GCCause::_g1_inc_collection_pause); 458 if (result != nullptr) { 459 assert(succeeded, "only way to get back a non-null result"); 460 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT, 461 Thread::current()->name(), p2i(result)); 462 return result; 463 } 464 465 if (succeeded) { 466 // We successfully scheduled a collection which failed to allocate. No 467 // point in trying to allocate further. We'll just return null. 468 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate " 469 SIZE_FORMAT " words", Thread::current()->name(), word_size); 470 return nullptr; 471 } 472 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words", 473 Thread::current()->name(), word_size); 474 } else { 475 // Failed to schedule a collection. 476 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 477 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating " 478 SIZE_FORMAT " words", Thread::current()->name(), word_size); 479 return nullptr; 480 } 481 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name()); 482 // The GCLocker is either active or the GCLocker initiated 483 // GC has not yet been performed. Stall until it is and 484 // then retry the allocation. 485 GCLocker::stall_until_clear(); 486 gclocker_retry_count += 1; 487 } 488 489 // We can reach here if we were unsuccessful in scheduling a 490 // collection (because another thread beat us to it) or if we were 491 // stalled due to the GC locker. In either can we should retry the 492 // allocation attempt in case another thread successfully 493 // performed a collection and reclaimed enough space. We do the 494 // first attempt (without holding the Heap_lock) here and the 495 // follow-on attempt will be at the start of the next loop 496 // iteration (after taking the Heap_lock). 497 size_t dummy = 0; 498 result = _allocator->attempt_allocation(word_size, word_size, &dummy); 499 if (result != nullptr) { 500 return result; 501 } 502 503 // Give a warning if we seem to be looping forever. 504 if ((QueuedAllocationWarningCount > 0) && 505 (try_count % QueuedAllocationWarningCount == 0)) { 506 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words", 507 Thread::current()->name(), try_count, word_size); 508 } 509 } 510 511 ShouldNotReachHere(); 512 return nullptr; 513 } 514 515 template <typename Func> 516 void G1CollectedHeap::iterate_regions_in_range(MemRegion range, const Func& func) { 517 // Mark each G1 region touched by the range as old, add it to 518 // the old set, and set top. 519 HeapRegion* curr_region = _hrm.addr_to_region(range.start()); 520 HeapRegion* end_region = _hrm.addr_to_region(range.last()); 521 522 while (curr_region != nullptr) { 523 bool is_last = curr_region == end_region; 524 HeapRegion* next_region = is_last ? nullptr : _hrm.next_region_in_heap(curr_region); 525 526 func(curr_region, is_last); 527 528 curr_region = next_region; 529 } 530 } 531 532 HeapWord* G1CollectedHeap::alloc_archive_region(size_t word_size, HeapWord* preferred_addr) { 533 assert(!is_init_completed(), "Expect to be called at JVM init time"); 534 MutexLocker x(Heap_lock); 535 536 MemRegion reserved = _hrm.reserved(); 537 538 if (reserved.word_size() <= word_size) { 539 log_info(gc, heap)("Unable to allocate regions as archive heap is too large; size requested = " SIZE_FORMAT 540 " bytes, heap = " SIZE_FORMAT " bytes", word_size, reserved.word_size()); 541 return nullptr; 542 } 543 544 // Temporarily disable pretouching of heap pages. This interface is used 545 // when mmap'ing archived heap data in, so pre-touching is wasted. 546 FlagSetting fs(AlwaysPreTouch, false); 547 548 size_t commits = 0; 549 // Attempt to allocate towards the end of the heap. 550 HeapWord* start_addr = reserved.end() - align_up(word_size, HeapRegion::GrainWords); 551 MemRegion range = MemRegion(start_addr, word_size); 552 HeapWord* last_address = range.last(); 553 if (!_hrm.allocate_containing_regions(range, &commits, workers())) { 554 return nullptr; 555 } 556 increase_used(word_size * HeapWordSize); 557 if (commits != 0) { 558 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B", 559 HeapRegion::GrainWords * HeapWordSize * commits); 560 } 561 562 // Mark each G1 region touched by the range as old, add it to 563 // the old set, and set top. 564 auto set_region_to_old = [&] (HeapRegion* r, bool is_last) { 565 assert(r->is_empty(), "Region already in use (%u)", r->hrm_index()); 566 567 HeapWord* top = is_last ? last_address + 1 : r->end(); 568 r->set_top(top); 569 570 r->set_old(); 571 _hr_printer.alloc(r); 572 _old_set.add(r); 573 }; 574 575 iterate_regions_in_range(range, set_region_to_old); 576 return start_addr; 577 } 578 579 void G1CollectedHeap::populate_archive_regions_bot_part(MemRegion range) { 580 assert(!is_init_completed(), "Expect to be called at JVM init time"); 581 582 iterate_regions_in_range(range, 583 [&] (HeapRegion* r, bool is_last) { 584 r->update_bot(); 585 }); 586 } 587 588 void G1CollectedHeap::dealloc_archive_regions(MemRegion range) { 589 assert(!is_init_completed(), "Expect to be called at JVM init time"); 590 MemRegion reserved = _hrm.reserved(); 591 size_t size_used = 0; 592 uint shrink_count = 0; 593 594 // Free the G1 regions that are within the specified range. 595 MutexLocker x(Heap_lock); 596 HeapWord* start_address = range.start(); 597 HeapWord* last_address = range.last(); 598 599 assert(reserved.contains(start_address) && reserved.contains(last_address), 600 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 601 p2i(start_address), p2i(last_address)); 602 size_used += range.byte_size(); 603 604 // Free, empty and uncommit regions with CDS archive content. 605 auto dealloc_archive_region = [&] (HeapRegion* r, bool is_last) { 606 guarantee(r->is_old(), "Expected old region at index %u", r->hrm_index()); 607 _old_set.remove(r); 608 r->set_free(); 609 r->set_top(r->bottom()); 610 _hrm.shrink_at(r->hrm_index(), 1); 611 shrink_count++; 612 }; 613 614 iterate_regions_in_range(range, dealloc_archive_region); 615 616 if (shrink_count != 0) { 617 log_debug(gc, ergo, heap)("Attempt heap shrinking (CDS archive regions). Total size: " SIZE_FORMAT "B", 618 HeapRegion::GrainWords * HeapWordSize * shrink_count); 619 // Explicit uncommit. 620 uncommit_regions(shrink_count); 621 } 622 decrease_used(size_used); 623 } 624 625 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size, 626 size_t desired_word_size, 627 size_t* actual_word_size) { 628 assert_heap_not_locked_and_not_at_safepoint(); 629 assert(!is_humongous(desired_word_size), "attempt_allocation() should not " 630 "be called for humongous allocation requests"); 631 632 HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size); 633 634 if (result == nullptr) { 635 *actual_word_size = desired_word_size; 636 result = attempt_allocation_slow(desired_word_size); 637 } 638 639 assert_heap_not_locked(); 640 if (result != nullptr) { 641 assert(*actual_word_size != 0, "Actual size must have been set here"); 642 dirty_young_block(result, *actual_word_size); 643 } else { 644 *actual_word_size = 0; 645 } 646 647 return result; 648 } 649 650 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) { 651 ResourceMark rm; // For retrieving the thread names in log messages. 652 653 // The structure of this method has a lot of similarities to 654 // attempt_allocation_slow(). The reason these two were not merged 655 // into a single one is that such a method would require several "if 656 // allocation is not humongous do this, otherwise do that" 657 // conditional paths which would obscure its flow. In fact, an early 658 // version of this code did use a unified method which was harder to 659 // follow and, as a result, it had subtle bugs that were hard to 660 // track down. So keeping these two methods separate allows each to 661 // be more readable. It will be good to keep these two in sync as 662 // much as possible. 663 664 assert_heap_not_locked_and_not_at_safepoint(); 665 assert(is_humongous(word_size), "attempt_allocation_humongous() " 666 "should only be called for humongous allocations"); 667 668 // Humongous objects can exhaust the heap quickly, so we should check if we 669 // need to start a marking cycle at each humongous object allocation. We do 670 // the check before we do the actual allocation. The reason for doing it 671 // before the allocation is that we avoid having to keep track of the newly 672 // allocated memory while we do a GC. 673 if (policy()->need_to_start_conc_mark("concurrent humongous allocation", 674 word_size)) { 675 collect(GCCause::_g1_humongous_allocation); 676 } 677 678 // We will loop until a) we manage to successfully perform the 679 // allocation or b) we successfully schedule a collection which 680 // fails to perform the allocation. b) is the only case when we'll 681 // return null. 682 HeapWord* result = nullptr; 683 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 684 bool should_try_gc; 685 uint gc_count_before; 686 687 688 { 689 MutexLocker x(Heap_lock); 690 691 size_t size_in_regions = humongous_obj_size_in_regions(word_size); 692 // Given that humongous objects are not allocated in young 693 // regions, we'll first try to do the allocation without doing a 694 // collection hoping that there's enough space in the heap. 695 result = humongous_obj_allocate(word_size); 696 if (result != nullptr) { 697 policy()->old_gen_alloc_tracker()-> 698 add_allocated_humongous_bytes_since_last_gc(size_in_regions * HeapRegion::GrainBytes); 699 return result; 700 } 701 702 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until 703 // the GCLocker initiated GC has been performed and then retry. This includes 704 // the case when the GC Locker is not active but has not been performed. 705 should_try_gc = !GCLocker::needs_gc(); 706 // Read the GC count while still holding the Heap_lock. 707 gc_count_before = total_collections(); 708 } 709 710 if (should_try_gc) { 711 bool succeeded; 712 result = do_collection_pause(word_size, gc_count_before, &succeeded, GCCause::_g1_humongous_allocation); 713 if (result != nullptr) { 714 assert(succeeded, "only way to get back a non-null result"); 715 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT, 716 Thread::current()->name(), p2i(result)); 717 size_t size_in_regions = humongous_obj_size_in_regions(word_size); 718 policy()->old_gen_alloc_tracker()-> 719 record_collection_pause_humongous_allocation(size_in_regions * HeapRegion::GrainBytes); 720 return result; 721 } 722 723 if (succeeded) { 724 // We successfully scheduled a collection which failed to allocate. No 725 // point in trying to allocate further. We'll just return null. 726 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate " 727 SIZE_FORMAT " words", Thread::current()->name(), word_size); 728 return nullptr; 729 } 730 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "", 731 Thread::current()->name(), word_size); 732 } else { 733 // Failed to schedule a collection. 734 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 735 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating " 736 SIZE_FORMAT " words", Thread::current()->name(), word_size); 737 return nullptr; 738 } 739 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name()); 740 // The GCLocker is either active or the GCLocker initiated 741 // GC has not yet been performed. Stall until it is and 742 // then retry the allocation. 743 GCLocker::stall_until_clear(); 744 gclocker_retry_count += 1; 745 } 746 747 748 // We can reach here if we were unsuccessful in scheduling a 749 // collection (because another thread beat us to it) or if we were 750 // stalled due to the GC locker. In either can we should retry the 751 // allocation attempt in case another thread successfully 752 // performed a collection and reclaimed enough space. 753 // Humongous object allocation always needs a lock, so we wait for the retry 754 // in the next iteration of the loop, unlike for the regular iteration case. 755 // Give a warning if we seem to be looping forever. 756 757 if ((QueuedAllocationWarningCount > 0) && 758 (try_count % QueuedAllocationWarningCount == 0)) { 759 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words", 760 Thread::current()->name(), try_count, word_size); 761 } 762 } 763 764 ShouldNotReachHere(); 765 return nullptr; 766 } 767 768 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size, 769 bool expect_null_mutator_alloc_region) { 770 assert_at_safepoint_on_vm_thread(); 771 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region, 772 "the current alloc region was unexpectedly found to be non-null"); 773 774 if (!is_humongous(word_size)) { 775 return _allocator->attempt_allocation_locked(word_size); 776 } else { 777 HeapWord* result = humongous_obj_allocate(word_size); 778 if (result != nullptr && policy()->need_to_start_conc_mark("STW humongous allocation")) { 779 collector_state()->set_initiate_conc_mark_if_possible(true); 780 } 781 return result; 782 } 783 784 ShouldNotReachHere(); 785 } 786 787 class PostCompactionPrinterClosure: public HeapRegionClosure { 788 private: 789 G1HRPrinter* _hr_printer; 790 public: 791 bool do_heap_region(HeapRegion* hr) { 792 assert(!hr->is_young(), "not expecting to find young regions"); 793 _hr_printer->post_compaction(hr); 794 return false; 795 } 796 797 PostCompactionPrinterClosure(G1HRPrinter* hr_printer) 798 : _hr_printer(hr_printer) { } 799 }; 800 801 void G1CollectedHeap::print_heap_after_full_collection() { 802 // Post collection region logging. 803 // We should do this after we potentially resize the heap so 804 // that all the COMMIT / UNCOMMIT events are generated before 805 // the compaction events. 806 if (_hr_printer.is_active()) { 807 PostCompactionPrinterClosure cl(hr_printer()); 808 heap_region_iterate(&cl); 809 } 810 } 811 812 bool G1CollectedHeap::abort_concurrent_cycle() { 813 // Disable discovery and empty the discovered lists 814 // for the CM ref processor. 815 _ref_processor_cm->disable_discovery(); 816 _ref_processor_cm->abandon_partial_discovery(); 817 _ref_processor_cm->verify_no_references_recorded(); 818 819 // Abandon current iterations of concurrent marking and concurrent 820 // refinement, if any are in progress. 821 return concurrent_mark()->concurrent_cycle_abort(); 822 } 823 824 void G1CollectedHeap::prepare_heap_for_full_collection() { 825 // Make sure we'll choose a new allocation region afterwards. 826 _allocator->release_mutator_alloc_regions(); 827 _allocator->abandon_gc_alloc_regions(); 828 829 // We may have added regions to the current incremental collection 830 // set between the last GC or pause and now. We need to clear the 831 // incremental collection set and then start rebuilding it afresh 832 // after this full GC. 833 abandon_collection_set(collection_set()); 834 835 _hrm.remove_all_free_regions(); 836 } 837 838 void G1CollectedHeap::verify_before_full_collection() { 839 assert_used_and_recalculate_used_equal(this); 840 if (!VerifyBeforeGC) { 841 return; 842 } 843 if (!G1HeapVerifier::should_verify(G1HeapVerifier::G1VerifyFull)) { 844 return; 845 } 846 _verifier->verify_region_sets_optional(); 847 _verifier->verify_before_gc(); 848 _verifier->verify_bitmap_clear(true /* above_tams_only */); 849 } 850 851 void G1CollectedHeap::prepare_for_mutator_after_full_collection() { 852 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 853 ClassLoaderDataGraph::purge(/*at_safepoint*/true); 854 DEBUG_ONLY(MetaspaceUtils::verify();) 855 856 // Prepare heap for normal collections. 857 assert(num_free_regions() == 0, "we should not have added any free regions"); 858 rebuild_region_sets(false /* free_list_only */); 859 abort_refinement(); 860 resize_heap_if_necessary(); 861 uncommit_regions_if_necessary(); 862 863 // Rebuild the code root lists for each region 864 rebuild_code_roots(); 865 866 start_new_collection_set(); 867 _allocator->init_mutator_alloc_regions(); 868 869 // Post collection state updates. 870 MetaspaceGC::compute_new_size(); 871 } 872 873 void G1CollectedHeap::abort_refinement() { 874 // Discard all remembered set updates and reset refinement statistics. 875 G1BarrierSet::dirty_card_queue_set().abandon_logs_and_stats(); 876 assert(G1BarrierSet::dirty_card_queue_set().num_cards() == 0, 877 "DCQS should be empty"); 878 concurrent_refine()->get_and_reset_refinement_stats(); 879 } 880 881 void G1CollectedHeap::verify_after_full_collection() { 882 if (!VerifyAfterGC) { 883 return; 884 } 885 if (!G1HeapVerifier::should_verify(G1HeapVerifier::G1VerifyFull)) { 886 return; 887 } 888 _hrm.verify_optional(); 889 _verifier->verify_region_sets_optional(); 890 _verifier->verify_after_gc(); 891 _verifier->verify_bitmap_clear(false /* above_tams_only */); 892 893 // At this point there should be no regions in the 894 // entire heap tagged as young. 895 assert(check_young_list_empty(), "young list should be empty at this point"); 896 897 // Note: since we've just done a full GC, concurrent 898 // marking is no longer active. Therefore we need not 899 // re-enable reference discovery for the CM ref processor. 900 // That will be done at the start of the next marking cycle. 901 // We also know that the STW processor should no longer 902 // discover any new references. 903 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition"); 904 assert(!_ref_processor_cm->discovery_enabled(), "Postcondition"); 905 _ref_processor_stw->verify_no_references_recorded(); 906 _ref_processor_cm->verify_no_references_recorded(); 907 } 908 909 bool G1CollectedHeap::do_full_collection(bool clear_all_soft_refs, 910 bool do_maximal_compaction) { 911 assert_at_safepoint_on_vm_thread(); 912 913 if (GCLocker::check_active_before_gc()) { 914 // Full GC was not completed. 915 return false; 916 } 917 918 const bool do_clear_all_soft_refs = clear_all_soft_refs || 919 soft_ref_policy()->should_clear_all_soft_refs(); 920 921 G1FullGCMark gc_mark; 922 GCTraceTime(Info, gc) tm("Pause Full", nullptr, gc_cause(), true); 923 G1FullCollector collector(this, do_clear_all_soft_refs, do_maximal_compaction, gc_mark.tracer()); 924 925 collector.prepare_collection(); 926 collector.collect(); 927 collector.complete_collection(); 928 929 // Full collection was successfully completed. 930 return true; 931 } 932 933 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) { 934 // Currently, there is no facility in the do_full_collection(bool) API to notify 935 // the caller that the collection did not succeed (e.g., because it was locked 936 // out by the GC locker). So, right now, we'll ignore the return value. 937 938 do_full_collection(clear_all_soft_refs, 939 false /* do_maximal_compaction */); 940 } 941 942 bool G1CollectedHeap::upgrade_to_full_collection() { 943 GCCauseSetter compaction(this, GCCause::_g1_compaction_pause); 944 log_info(gc, ergo)("Attempting full compaction clearing soft references"); 945 bool success = do_full_collection(true /* clear_all_soft_refs */, 946 false /* do_maximal_compaction */); 947 // do_full_collection only fails if blocked by GC locker and that can't 948 // be the case here since we only call this when already completed one gc. 949 assert(success, "invariant"); 950 return success; 951 } 952 953 void G1CollectedHeap::resize_heap_if_necessary() { 954 assert_at_safepoint_on_vm_thread(); 955 956 bool should_expand; 957 size_t resize_amount = _heap_sizing_policy->full_collection_resize_amount(should_expand); 958 959 if (resize_amount == 0) { 960 return; 961 } else if (should_expand) { 962 expand(resize_amount, _workers); 963 } else { 964 shrink(resize_amount); 965 } 966 } 967 968 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size, 969 bool do_gc, 970 bool maximal_compaction, 971 bool expect_null_mutator_alloc_region, 972 bool* gc_succeeded) { 973 *gc_succeeded = true; 974 // Let's attempt the allocation first. 975 HeapWord* result = 976 attempt_allocation_at_safepoint(word_size, 977 expect_null_mutator_alloc_region); 978 if (result != nullptr) { 979 return result; 980 } 981 982 // In a G1 heap, we're supposed to keep allocation from failing by 983 // incremental pauses. Therefore, at least for now, we'll favor 984 // expansion over collection. (This might change in the future if we can 985 // do something smarter than full collection to satisfy a failed alloc.) 986 result = expand_and_allocate(word_size); 987 if (result != nullptr) { 988 return result; 989 } 990 991 if (do_gc) { 992 GCCauseSetter compaction(this, GCCause::_g1_compaction_pause); 993 // Expansion didn't work, we'll try to do a Full GC. 994 // If maximal_compaction is set we clear all soft references and don't 995 // allow any dead wood to be left on the heap. 996 if (maximal_compaction) { 997 log_info(gc, ergo)("Attempting maximal full compaction clearing soft references"); 998 } else { 999 log_info(gc, ergo)("Attempting full compaction"); 1000 } 1001 *gc_succeeded = do_full_collection(maximal_compaction /* clear_all_soft_refs */ , 1002 maximal_compaction /* do_maximal_compaction */); 1003 } 1004 1005 return nullptr; 1006 } 1007 1008 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size, 1009 bool* succeeded) { 1010 assert_at_safepoint_on_vm_thread(); 1011 1012 // Attempts to allocate followed by Full GC. 1013 HeapWord* result = 1014 satisfy_failed_allocation_helper(word_size, 1015 true, /* do_gc */ 1016 false, /* maximum_collection */ 1017 false, /* expect_null_mutator_alloc_region */ 1018 succeeded); 1019 1020 if (result != nullptr || !*succeeded) { 1021 return result; 1022 } 1023 1024 // Attempts to allocate followed by Full GC that will collect all soft references. 1025 result = satisfy_failed_allocation_helper(word_size, 1026 true, /* do_gc */ 1027 true, /* maximum_collection */ 1028 true, /* expect_null_mutator_alloc_region */ 1029 succeeded); 1030 1031 if (result != nullptr || !*succeeded) { 1032 return result; 1033 } 1034 1035 // Attempts to allocate, no GC 1036 result = satisfy_failed_allocation_helper(word_size, 1037 false, /* do_gc */ 1038 false, /* maximum_collection */ 1039 true, /* expect_null_mutator_alloc_region */ 1040 succeeded); 1041 1042 if (result != nullptr) { 1043 return result; 1044 } 1045 1046 assert(!soft_ref_policy()->should_clear_all_soft_refs(), 1047 "Flag should have been handled and cleared prior to this point"); 1048 1049 // What else? We might try synchronous finalization later. If the total 1050 // space available is large enough for the allocation, then a more 1051 // complete compaction phase than we've tried so far might be 1052 // appropriate. 1053 return nullptr; 1054 } 1055 1056 // Attempting to expand the heap sufficiently 1057 // to support an allocation of the given "word_size". If 1058 // successful, perform the allocation and return the address of the 1059 // allocated block, or else null. 1060 1061 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) { 1062 assert_at_safepoint_on_vm_thread(); 1063 1064 _verifier->verify_region_sets_optional(); 1065 1066 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes); 1067 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B", 1068 word_size * HeapWordSize); 1069 1070 1071 if (expand(expand_bytes, _workers)) { 1072 _hrm.verify_optional(); 1073 _verifier->verify_region_sets_optional(); 1074 return attempt_allocation_at_safepoint(word_size, 1075 false /* expect_null_mutator_alloc_region */); 1076 } 1077 return nullptr; 1078 } 1079 1080 bool G1CollectedHeap::expand(size_t expand_bytes, WorkerThreads* pretouch_workers, double* expand_time_ms) { 1081 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); 1082 aligned_expand_bytes = align_up(aligned_expand_bytes, 1083 HeapRegion::GrainBytes); 1084 1085 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B", 1086 expand_bytes, aligned_expand_bytes); 1087 1088 if (is_maximal_no_gc()) { 1089 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)"); 1090 return false; 1091 } 1092 1093 double expand_heap_start_time_sec = os::elapsedTime(); 1094 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes); 1095 assert(regions_to_expand > 0, "Must expand by at least one region"); 1096 1097 uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers); 1098 if (expand_time_ms != nullptr) { 1099 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS; 1100 } 1101 1102 assert(expanded_by > 0, "must have failed during commit."); 1103 1104 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes; 1105 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition"); 1106 policy()->record_new_heap_size(num_regions()); 1107 1108 return true; 1109 } 1110 1111 bool G1CollectedHeap::expand_single_region(uint node_index) { 1112 uint expanded_by = _hrm.expand_on_preferred_node(node_index); 1113 1114 if (expanded_by == 0) { 1115 assert(is_maximal_no_gc(), "Should be no regions left, available: %u", _hrm.available()); 1116 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)"); 1117 return false; 1118 } 1119 1120 policy()->record_new_heap_size(num_regions()); 1121 return true; 1122 } 1123 1124 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) { 1125 size_t aligned_shrink_bytes = 1126 ReservedSpace::page_align_size_down(shrink_bytes); 1127 aligned_shrink_bytes = align_down(aligned_shrink_bytes, 1128 HeapRegion::GrainBytes); 1129 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes); 1130 1131 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove); 1132 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes; 1133 1134 log_debug(gc, ergo, heap)("Shrink the heap. requested shrinking amount: " SIZE_FORMAT "B aligned shrinking amount: " SIZE_FORMAT "B actual amount shrunk: " SIZE_FORMAT "B", 1135 shrink_bytes, aligned_shrink_bytes, shrunk_bytes); 1136 if (num_regions_removed > 0) { 1137 log_debug(gc, heap)("Uncommittable regions after shrink: %u", num_regions_removed); 1138 policy()->record_new_heap_size(num_regions()); 1139 } else { 1140 log_debug(gc, ergo, heap)("Did not shrink the heap (heap shrinking operation failed)"); 1141 } 1142 } 1143 1144 void G1CollectedHeap::shrink(size_t shrink_bytes) { 1145 _verifier->verify_region_sets_optional(); 1146 1147 // We should only reach here at the end of a Full GC or during Remark which 1148 // means we should not not be holding to any GC alloc regions. The method 1149 // below will make sure of that and do any remaining clean up. 1150 _allocator->abandon_gc_alloc_regions(); 1151 1152 // Instead of tearing down / rebuilding the free lists here, we 1153 // could instead use the remove_all_pending() method on free_list to 1154 // remove only the ones that we need to remove. 1155 _hrm.remove_all_free_regions(); 1156 shrink_helper(shrink_bytes); 1157 rebuild_region_sets(true /* free_list_only */); 1158 1159 _hrm.verify_optional(); 1160 _verifier->verify_region_sets_optional(); 1161 } 1162 1163 class OldRegionSetChecker : public HeapRegionSetChecker { 1164 public: 1165 void check_mt_safety() { 1166 // Master Old Set MT safety protocol: 1167 // (a) If we're at a safepoint, operations on the master old set 1168 // should be invoked: 1169 // - by the VM thread (which will serialize them), or 1170 // - by the GC workers while holding the FreeList_lock, if we're 1171 // at a safepoint for an evacuation pause (this lock is taken 1172 // anyway when an GC alloc region is retired so that a new one 1173 // is allocated from the free list), or 1174 // - by the GC workers while holding the OldSets_lock, if we're at a 1175 // safepoint for a cleanup pause. 1176 // (b) If we're not at a safepoint, operations on the master old set 1177 // should be invoked while holding the Heap_lock. 1178 1179 if (SafepointSynchronize::is_at_safepoint()) { 1180 guarantee(Thread::current()->is_VM_thread() || 1181 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(), 1182 "master old set MT safety protocol at a safepoint"); 1183 } else { 1184 guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint"); 1185 } 1186 } 1187 bool is_correct_type(HeapRegion* hr) { return hr->is_old(); } 1188 const char* get_description() { return "Old Regions"; } 1189 }; 1190 1191 class HumongousRegionSetChecker : public HeapRegionSetChecker { 1192 public: 1193 void check_mt_safety() { 1194 // Humongous Set MT safety protocol: 1195 // (a) If we're at a safepoint, operations on the master humongous 1196 // set should be invoked by either the VM thread (which will 1197 // serialize them) or by the GC workers while holding the 1198 // OldSets_lock. 1199 // (b) If we're not at a safepoint, operations on the master 1200 // humongous set should be invoked while holding the Heap_lock. 1201 1202 if (SafepointSynchronize::is_at_safepoint()) { 1203 guarantee(Thread::current()->is_VM_thread() || 1204 OldSets_lock->owned_by_self(), 1205 "master humongous set MT safety protocol at a safepoint"); 1206 } else { 1207 guarantee(Heap_lock->owned_by_self(), 1208 "master humongous set MT safety protocol outside a safepoint"); 1209 } 1210 } 1211 bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); } 1212 const char* get_description() { return "Humongous Regions"; } 1213 }; 1214 1215 G1CollectedHeap::G1CollectedHeap() : 1216 CollectedHeap(), 1217 _service_thread(nullptr), 1218 _periodic_gc_task(nullptr), 1219 _free_arena_memory_task(nullptr), 1220 _workers(nullptr), 1221 _card_table(nullptr), 1222 _collection_pause_end(Ticks::now()), 1223 _soft_ref_policy(), 1224 _old_set("Old Region Set", new OldRegionSetChecker()), 1225 _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()), 1226 _bot(nullptr), 1227 _listener(), 1228 _numa(G1NUMA::create()), 1229 _hrm(), 1230 _allocator(nullptr), 1231 _evac_failure_injector(), 1232 _verifier(nullptr), 1233 _summary_bytes_used(0), 1234 _bytes_used_during_gc(0), 1235 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight), 1236 _old_evac_stats("Old", OldPLABSize, PLABWeight), 1237 _monitoring_support(nullptr), 1238 _num_humongous_objects(0), 1239 _num_humongous_reclaim_candidates(0), 1240 _hr_printer(), 1241 _collector_state(), 1242 _old_marking_cycles_started(0), 1243 _old_marking_cycles_completed(0), 1244 _eden(), 1245 _survivor(), 1246 _gc_timer_stw(new STWGCTimer()), 1247 _gc_tracer_stw(new G1NewTracer()), 1248 _policy(new G1Policy(_gc_timer_stw)), 1249 _heap_sizing_policy(nullptr), 1250 _collection_set(this, _policy), 1251 _rem_set(nullptr), 1252 _card_set_config(), 1253 _card_set_freelist_pool(G1CardSetConfiguration::num_mem_object_types()), 1254 _cm(nullptr), 1255 _cm_thread(nullptr), 1256 _cr(nullptr), 1257 _task_queues(nullptr), 1258 _ref_processor_stw(nullptr), 1259 _is_alive_closure_stw(this), 1260 _is_subject_to_discovery_stw(this), 1261 _ref_processor_cm(nullptr), 1262 _is_alive_closure_cm(this), 1263 _is_subject_to_discovery_cm(this), 1264 _region_attr() { 1265 1266 _verifier = new G1HeapVerifier(this); 1267 1268 _allocator = new G1Allocator(this); 1269 1270 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _policy->analytics()); 1271 1272 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords); 1273 1274 // Override the default _filler_array_max_size so that no humongous filler 1275 // objects are created. 1276 _filler_array_max_size = _humongous_object_threshold_in_words; 1277 1278 // Override the default _stack_chunk_max_size so that no humongous stack chunks are created 1279 _stack_chunk_max_size = _humongous_object_threshold_in_words; 1280 1281 uint n_queues = ParallelGCThreads; 1282 _task_queues = new G1ScannerTasksQueueSet(n_queues); 1283 1284 for (uint i = 0; i < n_queues; i++) { 1285 G1ScannerTasksQueue* q = new G1ScannerTasksQueue(); 1286 _task_queues->register_queue(i, q); 1287 } 1288 1289 _gc_tracer_stw->initialize(); 1290 1291 guarantee(_task_queues != nullptr, "task_queues allocation failure."); 1292 } 1293 1294 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description, 1295 size_t size, 1296 size_t translation_factor) { 1297 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1); 1298 // Allocate a new reserved space, preferring to use large pages. 1299 ReservedSpace rs(size, preferred_page_size); 1300 size_t page_size = rs.page_size(); 1301 G1RegionToSpaceMapper* result = 1302 G1RegionToSpaceMapper::create_mapper(rs, 1303 size, 1304 page_size, 1305 HeapRegion::GrainBytes, 1306 translation_factor, 1307 mtGC); 1308 1309 os::trace_page_sizes_for_requested_size(description, 1310 size, 1311 preferred_page_size, 1312 rs.base(), 1313 rs.size(), 1314 page_size); 1315 1316 return result; 1317 } 1318 1319 jint G1CollectedHeap::initialize_concurrent_refinement() { 1320 jint ecode = JNI_OK; 1321 _cr = G1ConcurrentRefine::create(policy(), &ecode); 1322 return ecode; 1323 } 1324 1325 jint G1CollectedHeap::initialize_service_thread() { 1326 _service_thread = new G1ServiceThread(); 1327 if (_service_thread->osthread() == nullptr) { 1328 vm_shutdown_during_initialization("Could not create G1ServiceThread"); 1329 return JNI_ENOMEM; 1330 } 1331 return JNI_OK; 1332 } 1333 1334 jint G1CollectedHeap::initialize() { 1335 1336 // Necessary to satisfy locking discipline assertions. 1337 1338 MutexLocker x(Heap_lock); 1339 1340 // While there are no constraints in the GC code that HeapWordSize 1341 // be any particular value, there are multiple other areas in the 1342 // system which believe this to be true (e.g. oop->object_size in some 1343 // cases incorrectly returns the size in wordSize units rather than 1344 // HeapWordSize). 1345 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 1346 1347 size_t init_byte_size = InitialHeapSize; 1348 size_t reserved_byte_size = G1Arguments::heap_reserved_size_bytes(); 1349 1350 // Ensure that the sizes are properly aligned. 1351 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1352 Universe::check_alignment(reserved_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1353 Universe::check_alignment(reserved_byte_size, HeapAlignment, "g1 heap"); 1354 1355 // Reserve the maximum. 1356 1357 // When compressed oops are enabled, the preferred heap base 1358 // is calculated by subtracting the requested size from the 1359 // 32Gb boundary and using the result as the base address for 1360 // heap reservation. If the requested size is not aligned to 1361 // HeapRegion::GrainBytes (i.e. the alignment that is passed 1362 // into the ReservedHeapSpace constructor) then the actual 1363 // base of the reserved heap may end up differing from the 1364 // address that was requested (i.e. the preferred heap base). 1365 // If this happens then we could end up using a non-optimal 1366 // compressed oops mode. 1367 1368 ReservedHeapSpace heap_rs = Universe::reserve_heap(reserved_byte_size, 1369 HeapAlignment); 1370 1371 initialize_reserved_region(heap_rs); 1372 1373 // Create the barrier set for the entire reserved region. 1374 G1CardTable* ct = new G1CardTable(heap_rs.region()); 1375 G1BarrierSet* bs = new G1BarrierSet(ct); 1376 bs->initialize(); 1377 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity"); 1378 BarrierSet::set_barrier_set(bs); 1379 _card_table = ct; 1380 1381 { 1382 G1SATBMarkQueueSet& satbqs = bs->satb_mark_queue_set(); 1383 satbqs.set_process_completed_buffers_threshold(G1SATBProcessCompletedThreshold); 1384 satbqs.set_buffer_enqueue_threshold_percentage(G1SATBBufferEnqueueingThresholdPercent); 1385 } 1386 1387 // Create space mappers. 1388 size_t page_size = heap_rs.page_size(); 1389 G1RegionToSpaceMapper* heap_storage = 1390 G1RegionToSpaceMapper::create_mapper(heap_rs, 1391 heap_rs.size(), 1392 page_size, 1393 HeapRegion::GrainBytes, 1394 1, 1395 mtJavaHeap); 1396 if(heap_storage == nullptr) { 1397 vm_shutdown_during_initialization("Could not initialize G1 heap"); 1398 return JNI_ERR; 1399 } 1400 1401 os::trace_page_sizes("Heap", 1402 MinHeapSize, 1403 reserved_byte_size, 1404 heap_rs.base(), 1405 heap_rs.size(), 1406 page_size); 1407 heap_storage->set_mapping_changed_listener(&_listener); 1408 1409 // Create storage for the BOT, card table and the bitmap. 1410 G1RegionToSpaceMapper* bot_storage = 1411 create_aux_memory_mapper("Block Offset Table", 1412 G1BlockOffsetTable::compute_size(heap_rs.size() / HeapWordSize), 1413 G1BlockOffsetTable::heap_map_factor()); 1414 1415 G1RegionToSpaceMapper* cardtable_storage = 1416 create_aux_memory_mapper("Card Table", 1417 G1CardTable::compute_size(heap_rs.size() / HeapWordSize), 1418 G1CardTable::heap_map_factor()); 1419 1420 size_t bitmap_size = G1CMBitMap::compute_size(heap_rs.size()); 1421 G1RegionToSpaceMapper* bitmap_storage = 1422 create_aux_memory_mapper("Mark Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1423 1424 _hrm.initialize(heap_storage, bitmap_storage, bot_storage, cardtable_storage); 1425 _card_table->initialize(cardtable_storage); 1426 1427 // 6843694 - ensure that the maximum region index can fit 1428 // in the remembered set structures. 1429 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; 1430 guarantee((max_reserved_regions() - 1) <= max_region_idx, "too many regions"); 1431 1432 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not 1433 // start within the first card. 1434 guarantee((uintptr_t)(heap_rs.base()) >= G1CardTable::card_size(), "Java heap must not start within the first card."); 1435 G1FromCardCache::initialize(max_reserved_regions()); 1436 // Also create a G1 rem set. 1437 _rem_set = new G1RemSet(this, _card_table); 1438 _rem_set->initialize(max_reserved_regions()); 1439 1440 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; 1441 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); 1442 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region, 1443 "too many cards per region"); 1444 1445 HeapRegionRemSet::initialize(_reserved); 1446 1447 FreeRegionList::set_unrealistically_long_length(max_regions() + 1); 1448 1449 _bot = new G1BlockOffsetTable(reserved(), bot_storage); 1450 1451 { 1452 size_t granularity = HeapRegion::GrainBytes; 1453 1454 _region_attr.initialize(reserved(), granularity); 1455 } 1456 1457 _workers = new WorkerThreads("GC Thread", ParallelGCThreads); 1458 if (_workers == nullptr) { 1459 return JNI_ENOMEM; 1460 } 1461 _workers->initialize_workers(); 1462 1463 _numa->set_region_info(HeapRegion::GrainBytes, page_size); 1464 1465 // Create the G1ConcurrentMark data structure and thread. 1466 // (Must do this late, so that "max_[reserved_]regions" is defined.) 1467 _cm = new G1ConcurrentMark(this, bitmap_storage); 1468 _cm_thread = _cm->cm_thread(); 1469 1470 // Now expand into the initial heap size. 1471 if (!expand(init_byte_size, _workers)) { 1472 vm_shutdown_during_initialization("Failed to allocate initial heap."); 1473 return JNI_ENOMEM; 1474 } 1475 1476 // Perform any initialization actions delegated to the policy. 1477 policy()->init(this, &_collection_set); 1478 1479 jint ecode = initialize_concurrent_refinement(); 1480 if (ecode != JNI_OK) { 1481 return ecode; 1482 } 1483 1484 ecode = initialize_service_thread(); 1485 if (ecode != JNI_OK) { 1486 return ecode; 1487 } 1488 1489 // Create and schedule the periodic gc task on the service thread. 1490 _periodic_gc_task = new G1PeriodicGCTask("Periodic GC Task"); 1491 _service_thread->register_task(_periodic_gc_task); 1492 1493 _free_arena_memory_task = new G1MonotonicArenaFreeMemoryTask("Card Set Free Memory Task"); 1494 _service_thread->register_task(_free_arena_memory_task); 1495 1496 // Here we allocate the dummy HeapRegion that is required by the 1497 // G1AllocRegion class. 1498 HeapRegion* dummy_region = _hrm.get_dummy_region(); 1499 1500 // We'll re-use the same region whether the alloc region will 1501 // require BOT updates or not and, if it doesn't, then a non-young 1502 // region will complain that it cannot support allocations without 1503 // BOT updates. So we'll tag the dummy region as eden to avoid that. 1504 dummy_region->set_eden(); 1505 // Make sure it's full. 1506 dummy_region->set_top(dummy_region->end()); 1507 G1AllocRegion::setup(this, dummy_region); 1508 1509 _allocator->init_mutator_alloc_regions(); 1510 1511 // Do create of the monitoring and management support so that 1512 // values in the heap have been properly initialized. 1513 _monitoring_support = new G1MonitoringSupport(this); 1514 1515 _collection_set.initialize(max_reserved_regions()); 1516 1517 evac_failure_injector()->reset(); 1518 1519 G1InitLogger::print(); 1520 1521 GCForwarding::initialize(heap_rs.region(), HeapRegion::GrainWords); 1522 1523 return JNI_OK; 1524 } 1525 1526 bool G1CollectedHeap::concurrent_mark_is_terminating() const { 1527 return _cm_thread->should_terminate(); 1528 } 1529 1530 void G1CollectedHeap::stop() { 1531 // Stop all concurrent threads. We do this to make sure these threads 1532 // do not continue to execute and access resources (e.g. logging) 1533 // that are destroyed during shutdown. 1534 _cr->stop(); 1535 _service_thread->stop(); 1536 _cm_thread->stop(); 1537 } 1538 1539 void G1CollectedHeap::safepoint_synchronize_begin() { 1540 SuspendibleThreadSet::synchronize(); 1541 } 1542 1543 void G1CollectedHeap::safepoint_synchronize_end() { 1544 SuspendibleThreadSet::desynchronize(); 1545 } 1546 1547 void G1CollectedHeap::post_initialize() { 1548 CollectedHeap::post_initialize(); 1549 ref_processing_init(); 1550 } 1551 1552 void G1CollectedHeap::ref_processing_init() { 1553 // Reference processing in G1 currently works as follows: 1554 // 1555 // * There are two reference processor instances. One is 1556 // used to record and process discovered references 1557 // during concurrent marking; the other is used to 1558 // record and process references during STW pauses 1559 // (both full and incremental). 1560 // * Both ref processors need to 'span' the entire heap as 1561 // the regions in the collection set may be dotted around. 1562 // 1563 // * For the concurrent marking ref processor: 1564 // * Reference discovery is enabled at concurrent start. 1565 // * Reference discovery is disabled and the discovered 1566 // references processed etc during remarking. 1567 // * Reference discovery is MT (see below). 1568 // * Reference discovery requires a barrier (see below). 1569 // * Reference processing may or may not be MT 1570 // (depending on the value of ParallelRefProcEnabled 1571 // and ParallelGCThreads). 1572 // * A full GC disables reference discovery by the CM 1573 // ref processor and abandons any entries on it's 1574 // discovered lists. 1575 // 1576 // * For the STW processor: 1577 // * Non MT discovery is enabled at the start of a full GC. 1578 // * Processing and enqueueing during a full GC is non-MT. 1579 // * During a full GC, references are processed after marking. 1580 // 1581 // * Discovery (may or may not be MT) is enabled at the start 1582 // of an incremental evacuation pause. 1583 // * References are processed near the end of a STW evacuation pause. 1584 // * For both types of GC: 1585 // * Discovery is atomic - i.e. not concurrent. 1586 // * Reference discovery will not need a barrier. 1587 1588 // Concurrent Mark ref processor 1589 _ref_processor_cm = 1590 new ReferenceProcessor(&_is_subject_to_discovery_cm, 1591 ParallelGCThreads, // degree of mt processing 1592 // We discover with the gc worker threads during Remark, so both 1593 // thread counts must be considered for discovery. 1594 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery 1595 true, // Reference discovery is concurrent 1596 &_is_alive_closure_cm); // is alive closure 1597 1598 // STW ref processor 1599 _ref_processor_stw = 1600 new ReferenceProcessor(&_is_subject_to_discovery_stw, 1601 ParallelGCThreads, // degree of mt processing 1602 ParallelGCThreads, // degree of mt discovery 1603 false, // Reference discovery is not concurrent 1604 &_is_alive_closure_stw); // is alive closure 1605 } 1606 1607 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() { 1608 return &_soft_ref_policy; 1609 } 1610 1611 size_t G1CollectedHeap::capacity() const { 1612 return _hrm.length() * HeapRegion::GrainBytes; 1613 } 1614 1615 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const { 1616 return _hrm.total_free_bytes(); 1617 } 1618 1619 // Computes the sum of the storage used by the various regions. 1620 size_t G1CollectedHeap::used() const { 1621 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions(); 1622 return result; 1623 } 1624 1625 size_t G1CollectedHeap::used_unlocked() const { 1626 return _summary_bytes_used; 1627 } 1628 1629 class SumUsedClosure: public HeapRegionClosure { 1630 size_t _used; 1631 public: 1632 SumUsedClosure() : _used(0) {} 1633 bool do_heap_region(HeapRegion* r) { 1634 _used += r->used(); 1635 return false; 1636 } 1637 size_t result() { return _used; } 1638 }; 1639 1640 size_t G1CollectedHeap::recalculate_used() const { 1641 SumUsedClosure blk; 1642 heap_region_iterate(&blk); 1643 return blk.result(); 1644 } 1645 1646 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) { 1647 return GCCause::is_user_requested_gc(cause) && ExplicitGCInvokesConcurrent; 1648 } 1649 1650 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 1651 switch (cause) { 1652 case GCCause::_g1_humongous_allocation: return true; 1653 case GCCause::_g1_periodic_collection: return G1PeriodicGCInvokesConcurrent; 1654 case GCCause::_wb_breakpoint: return true; 1655 case GCCause::_codecache_GC_aggressive: return true; 1656 case GCCause::_codecache_GC_threshold: return true; 1657 default: return is_user_requested_concurrent_full_gc(cause); 1658 } 1659 } 1660 1661 void G1CollectedHeap::increment_old_marking_cycles_started() { 1662 assert(_old_marking_cycles_started == _old_marking_cycles_completed || 1663 _old_marking_cycles_started == _old_marking_cycles_completed + 1, 1664 "Wrong marking cycle count (started: %d, completed: %d)", 1665 _old_marking_cycles_started, _old_marking_cycles_completed); 1666 1667 _old_marking_cycles_started++; 1668 } 1669 1670 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent, 1671 bool whole_heap_examined) { 1672 MonitorLocker ml(G1OldGCCount_lock, Mutex::_no_safepoint_check_flag); 1673 1674 // We assume that if concurrent == true, then the caller is a 1675 // concurrent thread that was joined the Suspendible Thread 1676 // Set. If there's ever a cheap way to check this, we should add an 1677 // assert here. 1678 1679 // Given that this method is called at the end of a Full GC or of a 1680 // concurrent cycle, and those can be nested (i.e., a Full GC can 1681 // interrupt a concurrent cycle), the number of full collections 1682 // completed should be either one (in the case where there was no 1683 // nesting) or two (when a Full GC interrupted a concurrent cycle) 1684 // behind the number of full collections started. 1685 1686 // This is the case for the inner caller, i.e. a Full GC. 1687 assert(concurrent || 1688 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || 1689 (_old_marking_cycles_started == _old_marking_cycles_completed + 2), 1690 "for inner caller (Full GC): _old_marking_cycles_started = %u " 1691 "is inconsistent with _old_marking_cycles_completed = %u", 1692 _old_marking_cycles_started, _old_marking_cycles_completed); 1693 1694 // This is the case for the outer caller, i.e. the concurrent cycle. 1695 assert(!concurrent || 1696 (_old_marking_cycles_started == _old_marking_cycles_completed + 1), 1697 "for outer caller (concurrent cycle): " 1698 "_old_marking_cycles_started = %u " 1699 "is inconsistent with _old_marking_cycles_completed = %u", 1700 _old_marking_cycles_started, _old_marking_cycles_completed); 1701 1702 _old_marking_cycles_completed += 1; 1703 if (whole_heap_examined) { 1704 // Signal that we have completed a visit to all live objects. 1705 record_whole_heap_examined_timestamp(); 1706 } 1707 1708 // We need to clear the "in_progress" flag in the CM thread before 1709 // we wake up any waiters (especially when ExplicitInvokesConcurrent 1710 // is set) so that if a waiter requests another System.gc() it doesn't 1711 // incorrectly see that a marking cycle is still in progress. 1712 if (concurrent) { 1713 _cm_thread->set_idle(); 1714 } 1715 1716 // Notify threads waiting in System.gc() (with ExplicitGCInvokesConcurrent) 1717 // for a full GC to finish that their wait is over. 1718 ml.notify_all(); 1719 } 1720 1721 // Helper for collect(). 1722 static G1GCCounters collection_counters(G1CollectedHeap* g1h) { 1723 MutexLocker ml(Heap_lock); 1724 return G1GCCounters(g1h); 1725 } 1726 1727 void G1CollectedHeap::collect(GCCause::Cause cause) { 1728 try_collect(cause, collection_counters(this)); 1729 } 1730 1731 // Return true if (x < y) with allowance for wraparound. 1732 static bool gc_counter_less_than(uint x, uint y) { 1733 return (x - y) > (UINT_MAX/2); 1734 } 1735 1736 // LOG_COLLECT_CONCURRENTLY(cause, msg, args...) 1737 // Macro so msg printing is format-checked. 1738 #define LOG_COLLECT_CONCURRENTLY(cause, ...) \ 1739 do { \ 1740 LogTarget(Trace, gc) LOG_COLLECT_CONCURRENTLY_lt; \ 1741 if (LOG_COLLECT_CONCURRENTLY_lt.is_enabled()) { \ 1742 ResourceMark rm; /* For thread name. */ \ 1743 LogStream LOG_COLLECT_CONCURRENTLY_s(&LOG_COLLECT_CONCURRENTLY_lt); \ 1744 LOG_COLLECT_CONCURRENTLY_s.print("%s: Try Collect Concurrently (%s): ", \ 1745 Thread::current()->name(), \ 1746 GCCause::to_string(cause)); \ 1747 LOG_COLLECT_CONCURRENTLY_s.print(__VA_ARGS__); \ 1748 } \ 1749 } while (0) 1750 1751 #define LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, result) \ 1752 LOG_COLLECT_CONCURRENTLY(cause, "complete %s", BOOL_TO_STR(result)) 1753 1754 bool G1CollectedHeap::try_collect_concurrently(GCCause::Cause cause, 1755 uint gc_counter, 1756 uint old_marking_started_before) { 1757 assert_heap_not_locked(); 1758 assert(should_do_concurrent_full_gc(cause), 1759 "Non-concurrent cause %s", GCCause::to_string(cause)); 1760 1761 for (uint i = 1; true; ++i) { 1762 // Try to schedule concurrent start evacuation pause that will 1763 // start a concurrent cycle. 1764 LOG_COLLECT_CONCURRENTLY(cause, "attempt %u", i); 1765 VM_G1TryInitiateConcMark op(gc_counter, cause); 1766 VMThread::execute(&op); 1767 1768 // Request is trivially finished. 1769 if (cause == GCCause::_g1_periodic_collection) { 1770 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, op.gc_succeeded()); 1771 return op.gc_succeeded(); 1772 } 1773 1774 // If VMOp skipped initiating concurrent marking cycle because 1775 // we're terminating, then we're done. 1776 if (op.terminating()) { 1777 LOG_COLLECT_CONCURRENTLY(cause, "skipped: terminating"); 1778 return false; 1779 } 1780 1781 // Lock to get consistent set of values. 1782 uint old_marking_started_after; 1783 uint old_marking_completed_after; 1784 { 1785 MutexLocker ml(Heap_lock); 1786 // Update gc_counter for retrying VMOp if needed. Captured here to be 1787 // consistent with the values we use below for termination tests. If 1788 // a retry is needed after a possible wait, and another collection 1789 // occurs in the meantime, it will cause our retry to be skipped and 1790 // we'll recheck for termination with updated conditions from that 1791 // more recent collection. That's what we want, rather than having 1792 // our retry possibly perform an unnecessary collection. 1793 gc_counter = total_collections(); 1794 old_marking_started_after = _old_marking_cycles_started; 1795 old_marking_completed_after = _old_marking_cycles_completed; 1796 } 1797 1798 if (cause == GCCause::_wb_breakpoint) { 1799 if (op.gc_succeeded()) { 1800 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true); 1801 return true; 1802 } 1803 // When _wb_breakpoint there can't be another cycle or deferred. 1804 assert(!op.cycle_already_in_progress(), "invariant"); 1805 assert(!op.whitebox_attached(), "invariant"); 1806 // Concurrent cycle attempt might have been cancelled by some other 1807 // collection, so retry. Unlike other cases below, we want to retry 1808 // even if cancelled by a STW full collection, because we really want 1809 // to start a concurrent cycle. 1810 if (old_marking_started_before != old_marking_started_after) { 1811 LOG_COLLECT_CONCURRENTLY(cause, "ignoring STW full GC"); 1812 old_marking_started_before = old_marking_started_after; 1813 } 1814 } else if (!GCCause::is_user_requested_gc(cause)) { 1815 // For an "automatic" (not user-requested) collection, we just need to 1816 // ensure that progress is made. 1817 // 1818 // Request is finished if any of 1819 // (1) the VMOp successfully performed a GC, 1820 // (2) a concurrent cycle was already in progress, 1821 // (3) whitebox is controlling concurrent cycles, 1822 // (4) a new cycle was started (by this thread or some other), or 1823 // (5) a Full GC was performed. 1824 // Cases (4) and (5) are detected together by a change to 1825 // _old_marking_cycles_started. 1826 // 1827 // Note that (1) does not imply (4). If we're still in the mixed 1828 // phase of an earlier concurrent collection, the request to make the 1829 // collection a concurrent start won't be honored. If we don't check for 1830 // both conditions we'll spin doing back-to-back collections. 1831 if (op.gc_succeeded() || 1832 op.cycle_already_in_progress() || 1833 op.whitebox_attached() || 1834 (old_marking_started_before != old_marking_started_after)) { 1835 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true); 1836 return true; 1837 } 1838 } else { // User-requested GC. 1839 // For a user-requested collection, we want to ensure that a complete 1840 // full collection has been performed before returning, but without 1841 // waiting for more than needed. 1842 1843 // For user-requested GCs (unlike non-UR), a successful VMOp implies a 1844 // new cycle was started. That's good, because it's not clear what we 1845 // should do otherwise. Trying again just does back to back GCs. 1846 // Can't wait for someone else to start a cycle. And returning fails 1847 // to meet the goal of ensuring a full collection was performed. 1848 assert(!op.gc_succeeded() || 1849 (old_marking_started_before != old_marking_started_after), 1850 "invariant: succeeded %s, started before %u, started after %u", 1851 BOOL_TO_STR(op.gc_succeeded()), 1852 old_marking_started_before, old_marking_started_after); 1853 1854 // Request is finished if a full collection (concurrent or stw) 1855 // was started after this request and has completed, e.g. 1856 // started_before < completed_after. 1857 if (gc_counter_less_than(old_marking_started_before, 1858 old_marking_completed_after)) { 1859 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true); 1860 return true; 1861 } 1862 1863 if (old_marking_started_after != old_marking_completed_after) { 1864 // If there is an in-progress cycle (possibly started by us), then 1865 // wait for that cycle to complete, e.g. 1866 // while completed_now < started_after. 1867 LOG_COLLECT_CONCURRENTLY(cause, "wait"); 1868 MonitorLocker ml(G1OldGCCount_lock); 1869 while (gc_counter_less_than(_old_marking_cycles_completed, 1870 old_marking_started_after)) { 1871 ml.wait(); 1872 } 1873 // Request is finished if the collection we just waited for was 1874 // started after this request. 1875 if (old_marking_started_before != old_marking_started_after) { 1876 LOG_COLLECT_CONCURRENTLY(cause, "complete after wait"); 1877 return true; 1878 } 1879 } 1880 1881 // If VMOp was successful then it started a new cycle that the above 1882 // wait &etc should have recognized as finishing this request. This 1883 // differs from a non-user-request, where gc_succeeded does not imply 1884 // a new cycle was started. 1885 assert(!op.gc_succeeded(), "invariant"); 1886 1887 if (op.cycle_already_in_progress()) { 1888 // If VMOp failed because a cycle was already in progress, it 1889 // is now complete. But it didn't finish this user-requested 1890 // GC, so try again. 1891 LOG_COLLECT_CONCURRENTLY(cause, "retry after in-progress"); 1892 continue; 1893 } else if (op.whitebox_attached()) { 1894 // If WhiteBox wants control, wait for notification of a state 1895 // change in the controller, then try again. Don't wait for 1896 // release of control, since collections may complete while in 1897 // control. Note: This won't recognize a STW full collection 1898 // while waiting; we can't wait on multiple monitors. 1899 LOG_COLLECT_CONCURRENTLY(cause, "whitebox control stall"); 1900 MonitorLocker ml(ConcurrentGCBreakpoints::monitor()); 1901 if (ConcurrentGCBreakpoints::is_controlled()) { 1902 ml.wait(); 1903 } 1904 continue; 1905 } 1906 } 1907 1908 // Collection failed and should be retried. 1909 assert(op.transient_failure(), "invariant"); 1910 1911 if (GCLocker::is_active_and_needs_gc()) { 1912 // If GCLocker is active, wait until clear before retrying. 1913 LOG_COLLECT_CONCURRENTLY(cause, "gc-locker stall"); 1914 GCLocker::stall_until_clear(); 1915 } 1916 1917 LOG_COLLECT_CONCURRENTLY(cause, "retry"); 1918 } 1919 } 1920 1921 bool G1CollectedHeap::try_collect_fullgc(GCCause::Cause cause, 1922 const G1GCCounters& counters_before) { 1923 assert_heap_not_locked(); 1924 1925 while(true) { 1926 VM_G1CollectFull op(counters_before.total_collections(), 1927 counters_before.total_full_collections(), 1928 cause); 1929 VMThread::execute(&op); 1930 1931 // Request is trivially finished. 1932 if (!GCCause::is_explicit_full_gc(cause) || op.gc_succeeded()) { 1933 return op.gc_succeeded(); 1934 } 1935 1936 { 1937 MutexLocker ml(Heap_lock); 1938 if (counters_before.total_full_collections() != total_full_collections()) { 1939 return true; 1940 } 1941 } 1942 1943 if (GCLocker::is_active_and_needs_gc()) { 1944 // If GCLocker is active, wait until clear before retrying. 1945 GCLocker::stall_until_clear(); 1946 } 1947 } 1948 } 1949 1950 bool G1CollectedHeap::try_collect(GCCause::Cause cause, 1951 const G1GCCounters& counters_before) { 1952 if (should_do_concurrent_full_gc(cause)) { 1953 return try_collect_concurrently(cause, 1954 counters_before.total_collections(), 1955 counters_before.old_marking_cycles_started()); 1956 } else if (GCLocker::should_discard(cause, counters_before.total_collections())) { 1957 // Indicate failure to be consistent with VMOp failure due to 1958 // another collection slipping in after our gc_count but before 1959 // our request is processed. 1960 return false; 1961 } else if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc 1962 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { 1963 1964 // Schedule a standard evacuation pause. We're setting word_size 1965 // to 0 which means that we are not requesting a post-GC allocation. 1966 VM_G1CollectForAllocation op(0, /* word_size */ 1967 counters_before.total_collections(), 1968 cause); 1969 VMThread::execute(&op); 1970 return op.gc_succeeded(); 1971 } else { 1972 // Schedule a Full GC. 1973 return try_collect_fullgc(cause, counters_before); 1974 } 1975 } 1976 1977 void G1CollectedHeap::start_concurrent_gc_for_metadata_allocation(GCCause::Cause gc_cause) { 1978 GCCauseSetter x(this, gc_cause); 1979 1980 // At this point we are supposed to start a concurrent cycle. We 1981 // will do so if one is not already in progress. 1982 bool should_start = policy()->force_concurrent_start_if_outside_cycle(gc_cause); 1983 if (should_start) { 1984 do_collection_pause_at_safepoint(); 1985 } 1986 } 1987 1988 bool G1CollectedHeap::is_in(const void* p) const { 1989 return is_in_reserved(p) && _hrm.is_available(addr_to_region(p)); 1990 } 1991 1992 // Iteration functions. 1993 1994 // Iterates an ObjectClosure over all objects within a HeapRegion. 1995 1996 class IterateObjectClosureRegionClosure: public HeapRegionClosure { 1997 ObjectClosure* _cl; 1998 public: 1999 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} 2000 bool do_heap_region(HeapRegion* r) { 2001 if (!r->is_continues_humongous()) { 2002 r->object_iterate(_cl); 2003 } 2004 return false; 2005 } 2006 }; 2007 2008 void G1CollectedHeap::object_iterate(ObjectClosure* cl) { 2009 IterateObjectClosureRegionClosure blk(cl); 2010 heap_region_iterate(&blk); 2011 } 2012 2013 class G1ParallelObjectIterator : public ParallelObjectIteratorImpl { 2014 private: 2015 G1CollectedHeap* _heap; 2016 HeapRegionClaimer _claimer; 2017 2018 public: 2019 G1ParallelObjectIterator(uint thread_num) : 2020 _heap(G1CollectedHeap::heap()), 2021 _claimer(thread_num == 0 ? G1CollectedHeap::heap()->workers()->active_workers() : thread_num) {} 2022 2023 virtual void object_iterate(ObjectClosure* cl, uint worker_id) { 2024 _heap->object_iterate_parallel(cl, worker_id, &_claimer); 2025 } 2026 }; 2027 2028 ParallelObjectIteratorImpl* G1CollectedHeap::parallel_object_iterator(uint thread_num) { 2029 return new G1ParallelObjectIterator(thread_num); 2030 } 2031 2032 void G1CollectedHeap::object_iterate_parallel(ObjectClosure* cl, uint worker_id, HeapRegionClaimer* claimer) { 2033 IterateObjectClosureRegionClosure blk(cl); 2034 heap_region_par_iterate_from_worker_offset(&blk, claimer, worker_id); 2035 } 2036 2037 void G1CollectedHeap::keep_alive(oop obj) { 2038 G1BarrierSet::enqueue_preloaded(obj); 2039 } 2040 2041 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { 2042 _hrm.iterate(cl); 2043 } 2044 2045 void G1CollectedHeap::heap_region_iterate(HeapRegionIndexClosure* cl) const { 2046 _hrm.iterate(cl); 2047 } 2048 2049 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl, 2050 HeapRegionClaimer *hrclaimer, 2051 uint worker_id) const { 2052 _hrm.par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id)); 2053 } 2054 2055 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl, 2056 HeapRegionClaimer *hrclaimer) const { 2057 _hrm.par_iterate(cl, hrclaimer, 0); 2058 } 2059 2060 void G1CollectedHeap::collection_set_iterate_all(HeapRegionClosure* cl) { 2061 _collection_set.iterate(cl); 2062 } 2063 2064 void G1CollectedHeap::collection_set_par_iterate_all(HeapRegionClosure* cl, 2065 HeapRegionClaimer* hr_claimer, 2066 uint worker_id) { 2067 _collection_set.par_iterate(cl, hr_claimer, worker_id); 2068 } 2069 2070 void G1CollectedHeap::collection_set_iterate_increment_from(HeapRegionClosure *cl, 2071 HeapRegionClaimer* hr_claimer, 2072 uint worker_id) { 2073 _collection_set.iterate_incremental_part_from(cl, hr_claimer, worker_id); 2074 } 2075 2076 void G1CollectedHeap::par_iterate_regions_array(HeapRegionClosure* cl, 2077 HeapRegionClaimer* hr_claimer, 2078 const uint regions[], 2079 size_t length, 2080 uint worker_id) const { 2081 assert_at_safepoint(); 2082 if (length == 0) { 2083 return; 2084 } 2085 uint total_workers = workers()->active_workers(); 2086 2087 size_t start_pos = (worker_id * length) / total_workers; 2088 size_t cur_pos = start_pos; 2089 2090 do { 2091 uint region_idx = regions[cur_pos]; 2092 if (hr_claimer == nullptr || hr_claimer->claim_region(region_idx)) { 2093 HeapRegion* r = region_at(region_idx); 2094 bool result = cl->do_heap_region(r); 2095 guarantee(!result, "Must not cancel iteration"); 2096 } 2097 2098 cur_pos++; 2099 if (cur_pos == length) { 2100 cur_pos = 0; 2101 } 2102 } while (cur_pos != start_pos); 2103 } 2104 2105 HeapWord* G1CollectedHeap::block_start(const void* addr) const { 2106 HeapRegion* hr = heap_region_containing(addr); 2107 // The CollectedHeap API requires us to not fail for any given address within 2108 // the heap. HeapRegion::block_start() has been optimized to not accept addresses 2109 // outside of the allocated area. 2110 if (addr >= hr->top()) { 2111 return nullptr; 2112 } 2113 return hr->block_start(addr); 2114 } 2115 2116 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { 2117 HeapRegion* hr = heap_region_containing(addr); 2118 return hr->block_is_obj(addr, hr->parsable_bottom_acquire()); 2119 } 2120 2121 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { 2122 return (_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes; 2123 } 2124 2125 size_t G1CollectedHeap::tlab_used(Thread* ignored) const { 2126 return _eden.length() * HeapRegion::GrainBytes; 2127 } 2128 2129 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size 2130 // must be equal to the humongous object limit. 2131 size_t G1CollectedHeap::max_tlab_size() const { 2132 return align_down(_humongous_object_threshold_in_words, MinObjAlignment); 2133 } 2134 2135 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { 2136 return _allocator->unsafe_max_tlab_alloc(); 2137 } 2138 2139 size_t G1CollectedHeap::max_capacity() const { 2140 return max_regions() * HeapRegion::GrainBytes; 2141 } 2142 2143 void G1CollectedHeap::prepare_for_verify() { 2144 _verifier->prepare_for_verify(); 2145 } 2146 2147 void G1CollectedHeap::verify(VerifyOption vo) { 2148 _verifier->verify(vo); 2149 } 2150 2151 bool G1CollectedHeap::supports_concurrent_gc_breakpoints() const { 2152 return true; 2153 } 2154 2155 class PrintRegionClosure: public HeapRegionClosure { 2156 outputStream* _st; 2157 public: 2158 PrintRegionClosure(outputStream* st) : _st(st) {} 2159 bool do_heap_region(HeapRegion* r) { 2160 r->print_on(_st); 2161 return false; 2162 } 2163 }; 2164 2165 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2166 const HeapRegion* hr, 2167 const VerifyOption vo) const { 2168 switch (vo) { 2169 case VerifyOption::G1UseConcMarking: return is_obj_dead(obj, hr); 2170 case VerifyOption::G1UseFullMarking: return is_obj_dead_full(obj, hr); 2171 default: ShouldNotReachHere(); 2172 } 2173 return false; // keep some compilers happy 2174 } 2175 2176 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2177 const VerifyOption vo) const { 2178 switch (vo) { 2179 case VerifyOption::G1UseConcMarking: return is_obj_dead(obj); 2180 case VerifyOption::G1UseFullMarking: return is_obj_dead_full(obj); 2181 default: ShouldNotReachHere(); 2182 } 2183 return false; // keep some compilers happy 2184 } 2185 2186 void G1CollectedHeap::pin_object(JavaThread* thread, oop obj) { 2187 GCLocker::lock_critical(thread); 2188 } 2189 2190 void G1CollectedHeap::unpin_object(JavaThread* thread, oop obj) { 2191 GCLocker::unlock_critical(thread); 2192 } 2193 2194 void G1CollectedHeap::print_heap_regions() const { 2195 LogTarget(Trace, gc, heap, region) lt; 2196 if (lt.is_enabled()) { 2197 LogStream ls(lt); 2198 print_regions_on(&ls); 2199 } 2200 } 2201 2202 void G1CollectedHeap::print_on(outputStream* st) const { 2203 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked(); 2204 st->print(" %-20s", "garbage-first heap"); 2205 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 2206 capacity()/K, heap_used/K); 2207 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")", 2208 p2i(_hrm.reserved().start()), 2209 p2i(_hrm.reserved().end())); 2210 st->cr(); 2211 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); 2212 uint young_regions = young_regions_count(); 2213 st->print("%u young (" SIZE_FORMAT "K), ", young_regions, 2214 (size_t) young_regions * HeapRegion::GrainBytes / K); 2215 uint survivor_regions = survivor_regions_count(); 2216 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, 2217 (size_t) survivor_regions * HeapRegion::GrainBytes / K); 2218 st->cr(); 2219 if (_numa->is_enabled()) { 2220 uint num_nodes = _numa->num_active_nodes(); 2221 st->print(" remaining free region(s) on each NUMA node: "); 2222 const int* node_ids = _numa->node_ids(); 2223 for (uint node_index = 0; node_index < num_nodes; node_index++) { 2224 uint num_free_regions = _hrm.num_free_regions(node_index); 2225 st->print("%d=%u ", node_ids[node_index], num_free_regions); 2226 } 2227 st->cr(); 2228 } 2229 MetaspaceUtils::print_on(st); 2230 } 2231 2232 void G1CollectedHeap::print_regions_on(outputStream* st) const { 2233 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, " 2234 "HS=humongous(starts), HC=humongous(continues), " 2235 "CS=collection set, F=free, " 2236 "TAMS=top-at-mark-start, " 2237 "PB=parsable bottom"); 2238 PrintRegionClosure blk(st); 2239 heap_region_iterate(&blk); 2240 } 2241 2242 void G1CollectedHeap::print_extended_on(outputStream* st) const { 2243 print_on(st); 2244 2245 // Print the per-region information. 2246 st->cr(); 2247 print_regions_on(st); 2248 } 2249 2250 void G1CollectedHeap::print_on_error(outputStream* st) const { 2251 this->CollectedHeap::print_on_error(st); 2252 2253 if (_cm != nullptr) { 2254 st->cr(); 2255 _cm->print_on_error(st); 2256 } 2257 } 2258 2259 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { 2260 workers()->threads_do(tc); 2261 tc->do_thread(_cm_thread); 2262 _cm->threads_do(tc); 2263 _cr->threads_do(tc); 2264 tc->do_thread(_service_thread); 2265 } 2266 2267 void G1CollectedHeap::print_tracing_info() const { 2268 rem_set()->print_summary_info(); 2269 concurrent_mark()->print_summary_info(); 2270 } 2271 2272 bool G1CollectedHeap::print_location(outputStream* st, void* addr) const { 2273 return BlockLocationPrinter<G1CollectedHeap>::print_location(st, addr); 2274 } 2275 2276 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() { 2277 2278 size_t eden_used_bytes = _monitoring_support->eden_space_used(); 2279 size_t survivor_used_bytes = _monitoring_support->survivor_space_used(); 2280 size_t old_gen_used_bytes = _monitoring_support->old_gen_used(); 2281 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked(); 2282 2283 size_t eden_capacity_bytes = 2284 (policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes; 2285 2286 VirtualSpaceSummary heap_summary = create_heap_space_summary(); 2287 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes, eden_capacity_bytes, 2288 survivor_used_bytes, old_gen_used_bytes, num_regions()); 2289 } 2290 2291 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) { 2292 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(), 2293 stats->unused(), stats->used(), stats->region_end_waste(), 2294 stats->regions_filled(), stats->num_plab_filled(), 2295 stats->direct_allocated(), stats->num_direct_allocated(), 2296 stats->failure_used(), stats->failure_waste()); 2297 } 2298 2299 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) { 2300 const G1HeapSummary& heap_summary = create_g1_heap_summary(); 2301 gc_tracer->report_gc_heap_summary(when, heap_summary); 2302 2303 const MetaspaceSummary& metaspace_summary = create_metaspace_summary(); 2304 gc_tracer->report_metaspace_summary(when, metaspace_summary); 2305 } 2306 2307 void G1CollectedHeap::gc_prologue(bool full) { 2308 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 2309 2310 // Update common counters. 2311 increment_total_collections(full /* full gc */); 2312 if (full || collector_state()->in_concurrent_start_gc()) { 2313 increment_old_marking_cycles_started(); 2314 } 2315 } 2316 2317 void G1CollectedHeap::gc_epilogue(bool full) { 2318 // Update common counters. 2319 if (full) { 2320 // Update the number of full collections that have been completed. 2321 increment_old_marking_cycles_completed(false /* concurrent */, true /* liveness_completed */); 2322 } 2323 2324 #if COMPILER2_OR_JVMCI 2325 assert(DerivedPointerTable::is_empty(), "derived pointer present"); 2326 #endif 2327 2328 // We have just completed a GC. Update the soft reference 2329 // policy with the new heap occupancy 2330 Universe::heap()->update_capacity_and_used_at_gc(); 2331 2332 _collection_pause_end = Ticks::now(); 2333 2334 _free_arena_memory_task->notify_new_stats(&_young_gen_card_set_stats, 2335 &_collection_set_candidates_card_set_stats); 2336 } 2337 2338 uint G1CollectedHeap::uncommit_regions(uint region_limit) { 2339 return _hrm.uncommit_inactive_regions(region_limit); 2340 } 2341 2342 bool G1CollectedHeap::has_uncommittable_regions() { 2343 return _hrm.has_inactive_regions(); 2344 } 2345 2346 void G1CollectedHeap::uncommit_regions_if_necessary() { 2347 if (has_uncommittable_regions()) { 2348 G1UncommitRegionTask::enqueue(); 2349 } 2350 } 2351 2352 void G1CollectedHeap::verify_numa_regions(const char* desc) { 2353 LogTarget(Trace, gc, heap, verify) lt; 2354 2355 if (lt.is_enabled()) { 2356 LogStream ls(lt); 2357 // Iterate all heap regions to print matching between preferred numa id and actual numa id. 2358 G1NodeIndexCheckClosure cl(desc, _numa, &ls); 2359 heap_region_iterate(&cl); 2360 } 2361 } 2362 2363 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, 2364 uint gc_count_before, 2365 bool* succeeded, 2366 GCCause::Cause gc_cause) { 2367 assert_heap_not_locked_and_not_at_safepoint(); 2368 VM_G1CollectForAllocation op(word_size, gc_count_before, gc_cause); 2369 VMThread::execute(&op); 2370 2371 HeapWord* result = op.result(); 2372 bool ret_succeeded = op.prologue_succeeded() && op.gc_succeeded(); 2373 assert(result == nullptr || ret_succeeded, 2374 "the result should be null if the VM did not succeed"); 2375 *succeeded = ret_succeeded; 2376 2377 assert_heap_not_locked(); 2378 return result; 2379 } 2380 2381 void G1CollectedHeap::start_concurrent_cycle(bool concurrent_operation_is_full_mark) { 2382 assert(!_cm_thread->in_progress(), "Can not start concurrent operation while in progress"); 2383 2384 MutexLocker x(CGC_lock, Mutex::_no_safepoint_check_flag); 2385 if (concurrent_operation_is_full_mark) { 2386 _cm->post_concurrent_mark_start(); 2387 _cm_thread->start_full_mark(); 2388 } else { 2389 _cm->post_concurrent_undo_start(); 2390 _cm_thread->start_undo_mark(); 2391 } 2392 CGC_lock->notify(); 2393 } 2394 2395 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const { 2396 // We don't nominate objects with many remembered set entries, on 2397 // the assumption that such objects are likely still live. 2398 HeapRegionRemSet* rem_set = r->rem_set(); 2399 2400 return rem_set->occupancy_less_or_equal_than(G1EagerReclaimRemSetThreshold); 2401 } 2402 2403 #ifndef PRODUCT 2404 void G1CollectedHeap::verify_region_attr_remset_is_tracked() { 2405 class VerifyRegionAttrRemSet : public HeapRegionClosure { 2406 public: 2407 virtual bool do_heap_region(HeapRegion* r) { 2408 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 2409 bool const remset_is_tracked = g1h->region_attr(r->bottom()).remset_is_tracked(); 2410 assert(r->rem_set()->is_tracked() == remset_is_tracked, 2411 "Region %u remset tracking status (%s) different to region attribute (%s)", 2412 r->hrm_index(), BOOL_TO_STR(r->rem_set()->is_tracked()), BOOL_TO_STR(remset_is_tracked)); 2413 return false; 2414 } 2415 } cl; 2416 heap_region_iterate(&cl); 2417 } 2418 #endif 2419 2420 void G1CollectedHeap::start_new_collection_set() { 2421 collection_set()->start_incremental_building(); 2422 2423 clear_region_attr(); 2424 2425 guarantee(_eden.length() == 0, "eden should have been cleared"); 2426 policy()->transfer_survivors_to_cset(survivor()); 2427 2428 // We redo the verification but now wrt to the new CSet which 2429 // has just got initialized after the previous CSet was freed. 2430 _cm->verify_no_collection_set_oops(); 2431 } 2432 2433 G1HeapVerifier::G1VerifyType G1CollectedHeap::young_collection_verify_type() const { 2434 if (collector_state()->in_concurrent_start_gc()) { 2435 return G1HeapVerifier::G1VerifyConcurrentStart; 2436 } else if (collector_state()->in_young_only_phase()) { 2437 return G1HeapVerifier::G1VerifyYoungNormal; 2438 } else { 2439 return G1HeapVerifier::G1VerifyMixed; 2440 } 2441 } 2442 2443 void G1CollectedHeap::verify_before_young_collection(G1HeapVerifier::G1VerifyType type) { 2444 if (!VerifyBeforeGC) { 2445 return; 2446 } 2447 if (!G1HeapVerifier::should_verify(type)) { 2448 return; 2449 } 2450 Ticks start = Ticks::now(); 2451 _verifier->prepare_for_verify(); 2452 _verifier->verify_region_sets_optional(); 2453 _verifier->verify_dirty_young_regions(); 2454 _verifier->verify_before_gc(); 2455 verify_numa_regions("GC Start"); 2456 phase_times()->record_verify_before_time_ms((Ticks::now() - start).seconds() * MILLIUNITS); 2457 } 2458 2459 void G1CollectedHeap::verify_after_young_collection(G1HeapVerifier::G1VerifyType type) { 2460 if (!VerifyAfterGC) { 2461 return; 2462 } 2463 if (!G1HeapVerifier::should_verify(type)) { 2464 return; 2465 } 2466 Ticks start = Ticks::now(); 2467 _verifier->verify_after_gc(); 2468 verify_numa_regions("GC End"); 2469 _verifier->verify_region_sets_optional(); 2470 2471 if (collector_state()->in_concurrent_start_gc()) { 2472 log_debug(gc, verify)("Marking state"); 2473 _verifier->verify_marking_state(); 2474 } 2475 2476 phase_times()->record_verify_after_time_ms((Ticks::now() - start).seconds() * MILLIUNITS); 2477 } 2478 2479 void G1CollectedHeap::expand_heap_after_young_collection(){ 2480 size_t expand_bytes = _heap_sizing_policy->young_collection_expansion_amount(); 2481 if (expand_bytes > 0) { 2482 // No need for an ergo logging here, 2483 // expansion_amount() does this when it returns a value > 0. 2484 double expand_ms = 0.0; 2485 if (!expand(expand_bytes, _workers, &expand_ms)) { 2486 // We failed to expand the heap. Cannot do anything about it. 2487 } 2488 phase_times()->record_expand_heap_time(expand_ms); 2489 } 2490 } 2491 2492 bool G1CollectedHeap::do_collection_pause_at_safepoint() { 2493 assert_at_safepoint_on_vm_thread(); 2494 guarantee(!is_gc_active(), "collection is not reentrant"); 2495 2496 if (GCLocker::check_active_before_gc()) { 2497 return false; 2498 } 2499 2500 do_collection_pause_at_safepoint_helper(); 2501 return true; 2502 } 2503 2504 G1HeapPrinterMark::G1HeapPrinterMark(G1CollectedHeap* g1h) : _g1h(g1h), _heap_transition(g1h) { 2505 // This summary needs to be printed before incrementing total collections. 2506 _g1h->rem_set()->print_periodic_summary_info("Before GC RS summary", 2507 _g1h->total_collections(), 2508 true /* show_thread_times */); 2509 _g1h->print_heap_before_gc(); 2510 _g1h->print_heap_regions(); 2511 } 2512 2513 G1HeapPrinterMark::~G1HeapPrinterMark() { 2514 _g1h->policy()->print_age_table(); 2515 _g1h->rem_set()->print_coarsen_stats(); 2516 // We are at the end of the GC. Total collections has already been increased. 2517 _g1h->rem_set()->print_periodic_summary_info("After GC RS summary", 2518 _g1h->total_collections() - 1, 2519 false /* show_thread_times */); 2520 2521 _heap_transition.print(); 2522 _g1h->print_heap_regions(); 2523 _g1h->print_heap_after_gc(); 2524 // Print NUMA statistics. 2525 _g1h->numa()->print_statistics(); 2526 } 2527 2528 G1JFRTracerMark::G1JFRTracerMark(STWGCTimer* timer, GCTracer* tracer) : 2529 _timer(timer), _tracer(tracer) { 2530 2531 _timer->register_gc_start(); 2532 _tracer->report_gc_start(G1CollectedHeap::heap()->gc_cause(), _timer->gc_start()); 2533 G1CollectedHeap::heap()->trace_heap_before_gc(_tracer); 2534 } 2535 2536 G1JFRTracerMark::~G1JFRTracerMark() { 2537 G1CollectedHeap::heap()->trace_heap_after_gc(_tracer); 2538 _timer->register_gc_end(); 2539 _tracer->report_gc_end(_timer->gc_end(), _timer->time_partitions()); 2540 } 2541 2542 void G1CollectedHeap::prepare_for_mutator_after_young_collection() { 2543 Ticks start = Ticks::now(); 2544 2545 _survivor_evac_stats.adjust_desired_plab_size(); 2546 _old_evac_stats.adjust_desired_plab_size(); 2547 2548 // Start a new incremental collection set for the mutator phase. 2549 start_new_collection_set(); 2550 _allocator->init_mutator_alloc_regions(); 2551 2552 phase_times()->record_prepare_for_mutator_time_ms((Ticks::now() - start).seconds() * 1000.0); 2553 } 2554 2555 void G1CollectedHeap::retire_tlabs() { 2556 ensure_parsability(true); 2557 } 2558 2559 void G1CollectedHeap::do_collection_pause_at_safepoint_helper() { 2560 ResourceMark rm; 2561 2562 IsGCActiveMark active_gc_mark; 2563 GCIdMark gc_id_mark; 2564 SvcGCMarker sgcm(SvcGCMarker::MINOR); 2565 2566 GCTraceCPUTime tcpu(_gc_tracer_stw); 2567 2568 _bytes_used_during_gc = 0; 2569 2570 policy()->decide_on_concurrent_start_pause(); 2571 // Record whether this pause may need to trigger a concurrent operation. Later, 2572 // when we signal the G1ConcurrentMarkThread, the collector state has already 2573 // been reset for the next pause. 2574 bool should_start_concurrent_mark_operation = collector_state()->in_concurrent_start_gc(); 2575 2576 // Perform the collection. 2577 G1YoungCollector collector(gc_cause()); 2578 collector.collect(); 2579 2580 // It should now be safe to tell the concurrent mark thread to start 2581 // without its logging output interfering with the logging output 2582 // that came from the pause. 2583 if (should_start_concurrent_mark_operation) { 2584 verifier()->verify_bitmap_clear(true /* above_tams_only */); 2585 // CAUTION: after the start_concurrent_cycle() call below, the concurrent marking 2586 // thread(s) could be running concurrently with us. Make sure that anything 2587 // after this point does not assume that we are the only GC thread running. 2588 // Note: of course, the actual marking work will not start until the safepoint 2589 // itself is released in SuspendibleThreadSet::desynchronize(). 2590 start_concurrent_cycle(collector.concurrent_operation_is_full_mark()); 2591 ConcurrentGCBreakpoints::notify_idle_to_active(); 2592 } 2593 } 2594 2595 void G1CollectedHeap::complete_cleaning(bool class_unloading_occurred) { 2596 uint num_workers = workers()->active_workers(); 2597 G1ParallelCleaningTask unlink_task(num_workers, class_unloading_occurred); 2598 workers()->run_task(&unlink_task); 2599 } 2600 2601 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) { 2602 assert(obj != nullptr, "must not be null"); 2603 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj)); 2604 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below 2605 // may falsely indicate that this is not the case here: however the collection set only 2606 // contains old regions when concurrent mark is not running. 2607 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor(); 2608 } 2609 2610 void G1CollectedHeap::make_pending_list_reachable() { 2611 if (collector_state()->in_concurrent_start_gc()) { 2612 oop pll_head = Universe::reference_pending_list(); 2613 if (pll_head != nullptr) { 2614 // Any valid worker id is fine here as we are in the VM thread and single-threaded. 2615 _cm->mark_in_bitmap(0 /* worker_id */, pll_head); 2616 } 2617 } 2618 } 2619 2620 void G1CollectedHeap::set_humongous_stats(uint num_humongous_total, uint num_humongous_candidates) { 2621 _num_humongous_objects = num_humongous_total; 2622 _num_humongous_reclaim_candidates = num_humongous_candidates; 2623 } 2624 2625 bool G1CollectedHeap::should_sample_collection_set_candidates() const { 2626 const G1CollectionSetCandidates* candidates = collection_set()->candidates(); 2627 return !candidates->is_empty(); 2628 } 2629 2630 void G1CollectedHeap::set_collection_set_candidates_stats(G1MonotonicArenaMemoryStats& stats) { 2631 _collection_set_candidates_card_set_stats = stats; 2632 } 2633 2634 void G1CollectedHeap::set_young_gen_card_set_stats(const G1MonotonicArenaMemoryStats& stats) { 2635 _young_gen_card_set_stats = stats; 2636 } 2637 2638 void G1CollectedHeap::record_obj_copy_mem_stats() { 2639 policy()->old_gen_alloc_tracker()-> 2640 add_allocated_bytes_since_last_gc(_old_evac_stats.allocated() * HeapWordSize); 2641 2642 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats), 2643 create_g1_evac_summary(&_old_evac_stats)); 2644 } 2645 2646 void G1CollectedHeap::clear_bitmap_for_region(HeapRegion* hr) { 2647 concurrent_mark()->clear_bitmap_for_region(hr); 2648 } 2649 2650 void G1CollectedHeap::free_region(HeapRegion* hr, FreeRegionList* free_list) { 2651 assert(!hr->is_free(), "the region should not be free"); 2652 assert(!hr->is_empty(), "the region should not be empty"); 2653 assert(_hrm.is_available(hr->hrm_index()), "region should be committed"); 2654 2655 // Reset region metadata to allow reuse. 2656 hr->hr_clear(true /* clear_space */); 2657 _policy->remset_tracker()->update_at_free(hr); 2658 2659 if (free_list != nullptr) { 2660 free_list->add_ordered(hr); 2661 } 2662 } 2663 2664 void G1CollectedHeap::retain_region(HeapRegion* hr) { 2665 MutexLocker x(G1RareEvent_lock, Mutex::_no_safepoint_check_flag); 2666 collection_set()->candidates()->add_retained_region_unsorted(hr); 2667 } 2668 2669 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 2670 FreeRegionList* free_list) { 2671 assert(hr->is_humongous(), "this is only for humongous regions"); 2672 hr->clear_humongous(); 2673 free_region(hr, free_list); 2674 } 2675 2676 void G1CollectedHeap::remove_from_old_gen_sets(const uint old_regions_removed, 2677 const uint humongous_regions_removed) { 2678 if (old_regions_removed > 0 || humongous_regions_removed > 0) { 2679 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag); 2680 _old_set.bulk_remove(old_regions_removed); 2681 _humongous_set.bulk_remove(humongous_regions_removed); 2682 } 2683 2684 } 2685 2686 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) { 2687 assert(list != nullptr, "list can't be null"); 2688 if (!list->is_empty()) { 2689 MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag); 2690 _hrm.insert_list_into_free_list(list); 2691 } 2692 } 2693 2694 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) { 2695 decrease_used(bytes); 2696 } 2697 2698 void G1CollectedHeap::clear_eden() { 2699 _eden.clear(); 2700 } 2701 2702 void G1CollectedHeap::clear_collection_set() { 2703 collection_set()->clear(); 2704 } 2705 2706 void G1CollectedHeap::rebuild_free_region_list() { 2707 Ticks start = Ticks::now(); 2708 _hrm.rebuild_free_list(workers()); 2709 phase_times()->record_total_rebuild_freelist_time_ms((Ticks::now() - start).seconds() * 1000.0); 2710 } 2711 2712 class G1AbandonCollectionSetClosure : public HeapRegionClosure { 2713 public: 2714 virtual bool do_heap_region(HeapRegion* r) { 2715 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index()); 2716 G1CollectedHeap::heap()->clear_region_attr(r); 2717 r->clear_young_index_in_cset(); 2718 return false; 2719 } 2720 }; 2721 2722 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) { 2723 G1AbandonCollectionSetClosure cl; 2724 collection_set_iterate_all(&cl); 2725 2726 collection_set->clear(); 2727 collection_set->stop_incremental_building(); 2728 } 2729 2730 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) { 2731 return _allocator->is_retained_old_region(hr); 2732 } 2733 2734 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 2735 _eden.add(hr); 2736 _policy->set_region_eden(hr); 2737 } 2738 2739 #ifdef ASSERT 2740 2741 class NoYoungRegionsClosure: public HeapRegionClosure { 2742 private: 2743 bool _success; 2744 public: 2745 NoYoungRegionsClosure() : _success(true) { } 2746 bool do_heap_region(HeapRegion* r) { 2747 if (r->is_young()) { 2748 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young", 2749 p2i(r->bottom()), p2i(r->end())); 2750 _success = false; 2751 } 2752 return false; 2753 } 2754 bool success() { return _success; } 2755 }; 2756 2757 bool G1CollectedHeap::check_young_list_empty() { 2758 bool ret = (young_regions_count() == 0); 2759 2760 NoYoungRegionsClosure closure; 2761 heap_region_iterate(&closure); 2762 ret = ret && closure.success(); 2763 2764 return ret; 2765 } 2766 2767 #endif // ASSERT 2768 2769 // Remove the given HeapRegion from the appropriate region set. 2770 void G1CollectedHeap::prepare_region_for_full_compaction(HeapRegion* hr) { 2771 if (hr->is_humongous()) { 2772 _humongous_set.remove(hr); 2773 } else if (hr->is_old()) { 2774 _old_set.remove(hr); 2775 } else if (hr->is_young()) { 2776 // Note that emptying the eden and survivor lists is postponed and instead 2777 // done as the first step when rebuilding the regions sets again. The reason 2778 // for this is that during a full GC string deduplication needs to know if 2779 // a collected region was young or old when the full GC was initiated. 2780 hr->uninstall_surv_rate_group(); 2781 } else { 2782 // We ignore free regions, we'll empty the free list afterwards. 2783 assert(hr->is_free(), "it cannot be another type"); 2784 } 2785 } 2786 2787 void G1CollectedHeap::increase_used(size_t bytes) { 2788 _summary_bytes_used += bytes; 2789 } 2790 2791 void G1CollectedHeap::decrease_used(size_t bytes) { 2792 assert(_summary_bytes_used >= bytes, 2793 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT, 2794 _summary_bytes_used, bytes); 2795 _summary_bytes_used -= bytes; 2796 } 2797 2798 void G1CollectedHeap::set_used(size_t bytes) { 2799 _summary_bytes_used = bytes; 2800 } 2801 2802 class RebuildRegionSetsClosure : public HeapRegionClosure { 2803 private: 2804 bool _free_list_only; 2805 2806 HeapRegionSet* _old_set; 2807 HeapRegionSet* _humongous_set; 2808 2809 HeapRegionManager* _hrm; 2810 2811 size_t _total_used; 2812 2813 public: 2814 RebuildRegionSetsClosure(bool free_list_only, 2815 HeapRegionSet* old_set, 2816 HeapRegionSet* humongous_set, 2817 HeapRegionManager* hrm) : 2818 _free_list_only(free_list_only), _old_set(old_set), 2819 _humongous_set(humongous_set), _hrm(hrm), _total_used(0) { 2820 assert(_hrm->num_free_regions() == 0, "pre-condition"); 2821 if (!free_list_only) { 2822 assert(_old_set->is_empty(), "pre-condition"); 2823 assert(_humongous_set->is_empty(), "pre-condition"); 2824 } 2825 } 2826 2827 bool do_heap_region(HeapRegion* r) { 2828 if (r->is_empty()) { 2829 assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets."); 2830 // Add free regions to the free list 2831 r->set_free(); 2832 _hrm->insert_into_free_list(r); 2833 } else if (!_free_list_only) { 2834 assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared."); 2835 2836 if (r->is_humongous()) { 2837 _humongous_set->add(r); 2838 } else { 2839 assert(r->is_young() || r->is_free() || r->is_old(), "invariant"); 2840 // We now move all (non-humongous, non-old) regions to old gen, 2841 // and register them as such. 2842 r->move_to_old(); 2843 _old_set->add(r); 2844 } 2845 _total_used += r->used(); 2846 } 2847 2848 return false; 2849 } 2850 2851 size_t total_used() { 2852 return _total_used; 2853 } 2854 }; 2855 2856 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { 2857 assert_at_safepoint_on_vm_thread(); 2858 2859 if (!free_list_only) { 2860 _eden.clear(); 2861 _survivor.clear(); 2862 } 2863 2864 RebuildRegionSetsClosure cl(free_list_only, 2865 &_old_set, &_humongous_set, 2866 &_hrm); 2867 heap_region_iterate(&cl); 2868 2869 if (!free_list_only) { 2870 set_used(cl.total_used()); 2871 } 2872 assert_used_and_recalculate_used_equal(this); 2873 } 2874 2875 // Methods for the mutator alloc region 2876 2877 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 2878 bool force, 2879 uint node_index) { 2880 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 2881 bool should_allocate = policy()->should_allocate_mutator_region(); 2882 if (force || should_allocate) { 2883 HeapRegion* new_alloc_region = new_region(word_size, 2884 HeapRegionType::Eden, 2885 false /* do_expand */, 2886 node_index); 2887 if (new_alloc_region != nullptr) { 2888 set_region_short_lived_locked(new_alloc_region); 2889 _hr_printer.alloc(new_alloc_region, !should_allocate); 2890 _policy->remset_tracker()->update_at_allocate(new_alloc_region); 2891 return new_alloc_region; 2892 } 2893 } 2894 return nullptr; 2895 } 2896 2897 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 2898 size_t allocated_bytes) { 2899 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 2900 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden"); 2901 2902 collection_set()->add_eden_region(alloc_region); 2903 increase_used(allocated_bytes); 2904 _eden.add_used_bytes(allocated_bytes); 2905 _hr_printer.retire(alloc_region); 2906 2907 // We update the eden sizes here, when the region is retired, 2908 // instead of when it's allocated, since this is the point that its 2909 // used space has been recorded in _summary_bytes_used. 2910 monitoring_support()->update_eden_size(); 2911 } 2912 2913 // Methods for the GC alloc regions 2914 2915 bool G1CollectedHeap::has_more_regions(G1HeapRegionAttr dest) { 2916 if (dest.is_old()) { 2917 return true; 2918 } else { 2919 return survivor_regions_count() < policy()->max_survivor_regions(); 2920 } 2921 } 2922 2923 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest, uint node_index) { 2924 assert(FreeList_lock->owned_by_self(), "pre-condition"); 2925 2926 if (!has_more_regions(dest)) { 2927 return nullptr; 2928 } 2929 2930 HeapRegionType type; 2931 if (dest.is_young()) { 2932 type = HeapRegionType::Survivor; 2933 } else { 2934 type = HeapRegionType::Old; 2935 } 2936 2937 HeapRegion* new_alloc_region = new_region(word_size, 2938 type, 2939 true /* do_expand */, 2940 node_index); 2941 2942 if (new_alloc_region != nullptr) { 2943 if (type.is_survivor()) { 2944 new_alloc_region->set_survivor(); 2945 _survivor.add(new_alloc_region); 2946 register_new_survivor_region_with_region_attr(new_alloc_region); 2947 } else { 2948 new_alloc_region->set_old(); 2949 } 2950 _policy->remset_tracker()->update_at_allocate(new_alloc_region); 2951 register_region_with_region_attr(new_alloc_region); 2952 _hr_printer.alloc(new_alloc_region); 2953 return new_alloc_region; 2954 } 2955 return nullptr; 2956 } 2957 2958 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 2959 size_t allocated_bytes, 2960 G1HeapRegionAttr dest) { 2961 _bytes_used_during_gc += allocated_bytes; 2962 if (dest.is_old()) { 2963 old_set_add(alloc_region); 2964 } else { 2965 assert(dest.is_young(), "Retiring alloc region should be young (%d)", dest.type()); 2966 _survivor.add_used_bytes(allocated_bytes); 2967 } 2968 2969 bool const during_im = collector_state()->in_concurrent_start_gc(); 2970 if (during_im && allocated_bytes > 0) { 2971 _cm->add_root_region(alloc_region); 2972 } 2973 _hr_printer.retire(alloc_region); 2974 } 2975 2976 HeapRegion* G1CollectedHeap::alloc_highest_free_region() { 2977 bool expanded = false; 2978 uint index = _hrm.find_highest_free(&expanded); 2979 2980 if (index != G1_NO_HRM_INDEX) { 2981 if (expanded) { 2982 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B", 2983 HeapRegion::GrainWords * HeapWordSize); 2984 } 2985 return _hrm.allocate_free_regions_starting_at(index, 1); 2986 } 2987 return nullptr; 2988 } 2989 2990 void G1CollectedHeap::mark_evac_failure_object(uint worker_id, const oop obj, size_t obj_size) const { 2991 assert(!_cm->is_marked_in_bitmap(obj), "must be"); 2992 2993 _cm->raw_mark_in_bitmap(obj); 2994 } 2995 2996 // Optimized nmethod scanning 2997 class RegisterNMethodOopClosure: public OopClosure { 2998 G1CollectedHeap* _g1h; 2999 nmethod* _nm; 3000 3001 public: 3002 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 3003 _g1h(g1h), _nm(nm) {} 3004 3005 void do_oop(oop* p) { 3006 oop heap_oop = RawAccess<>::oop_load(p); 3007 if (!CompressedOops::is_null(heap_oop)) { 3008 oop obj = CompressedOops::decode_not_null(heap_oop); 3009 HeapRegion* hr = _g1h->heap_region_containing(obj); 3010 assert(!hr->is_continues_humongous(), 3011 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 3012 " starting at " HR_FORMAT, 3013 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 3014 3015 // HeapRegion::add_code_root_locked() avoids adding duplicate entries. 3016 hr->add_code_root_locked(_nm); 3017 } 3018 } 3019 3020 void do_oop(narrowOop* p) { ShouldNotReachHere(); } 3021 }; 3022 3023 class UnregisterNMethodOopClosure: public OopClosure { 3024 G1CollectedHeap* _g1h; 3025 nmethod* _nm; 3026 3027 public: 3028 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 3029 _g1h(g1h), _nm(nm) {} 3030 3031 void do_oop(oop* p) { 3032 oop heap_oop = RawAccess<>::oop_load(p); 3033 if (!CompressedOops::is_null(heap_oop)) { 3034 oop obj = CompressedOops::decode_not_null(heap_oop); 3035 HeapRegion* hr = _g1h->heap_region_containing(obj); 3036 assert(!hr->is_continues_humongous(), 3037 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 3038 " starting at " HR_FORMAT, 3039 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 3040 3041 hr->remove_code_root(_nm); 3042 } 3043 } 3044 3045 void do_oop(narrowOop* p) { ShouldNotReachHere(); } 3046 }; 3047 3048 void G1CollectedHeap::register_nmethod(nmethod* nm) { 3049 guarantee(nm != nullptr, "sanity"); 3050 RegisterNMethodOopClosure reg_cl(this, nm); 3051 nm->oops_do(®_cl); 3052 } 3053 3054 void G1CollectedHeap::unregister_nmethod(nmethod* nm) { 3055 guarantee(nm != nullptr, "sanity"); 3056 UnregisterNMethodOopClosure reg_cl(this, nm); 3057 nm->oops_do(®_cl, true); 3058 } 3059 3060 void G1CollectedHeap::update_used_after_gc(bool evacuation_failed) { 3061 if (evacuation_failed) { 3062 // Reset the G1EvacuationFailureALot counters and flags 3063 evac_failure_injector()->reset(); 3064 3065 set_used(recalculate_used()); 3066 } else { 3067 // The "used" of the collection set have already been subtracted 3068 // when they were freed. Add in the bytes used. 3069 increase_used(_bytes_used_during_gc); 3070 } 3071 } 3072 3073 class RebuildCodeRootClosure: public CodeBlobClosure { 3074 G1CollectedHeap* _g1h; 3075 3076 public: 3077 RebuildCodeRootClosure(G1CollectedHeap* g1h) : 3078 _g1h(g1h) {} 3079 3080 void do_code_blob(CodeBlob* cb) { 3081 nmethod* nm = cb->as_nmethod_or_null(); 3082 if (nm != nullptr) { 3083 _g1h->register_nmethod(nm); 3084 } 3085 } 3086 }; 3087 3088 void G1CollectedHeap::rebuild_code_roots() { 3089 RebuildCodeRootClosure blob_cl(this); 3090 CodeCache::blobs_do(&blob_cl); 3091 } 3092 3093 void G1CollectedHeap::initialize_serviceability() { 3094 _monitoring_support->initialize_serviceability(); 3095 } 3096 3097 MemoryUsage G1CollectedHeap::memory_usage() { 3098 return _monitoring_support->memory_usage(); 3099 } 3100 3101 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() { 3102 return _monitoring_support->memory_managers(); 3103 } 3104 3105 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() { 3106 return _monitoring_support->memory_pools(); 3107 } 3108 3109 void G1CollectedHeap::fill_with_dummy_object(HeapWord* start, HeapWord* end, bool zap) { 3110 HeapRegion* region = heap_region_containing(start); 3111 region->fill_with_dummy_object(start, pointer_delta(end, start), zap); 3112 } 3113 3114 void G1CollectedHeap::start_codecache_marking_cycle_if_inactive(bool concurrent_mark_start) { 3115 // We can reach here with an active code cache marking cycle either because the 3116 // previous G1 concurrent marking cycle was undone (if heap occupancy after the 3117 // concurrent start young collection was below the threshold) or aborted. See 3118 // CodeCache::on_gc_marking_cycle_finish() why this is. We must not start a new code 3119 // cache cycle then. If we are about to start a new g1 concurrent marking cycle we 3120 // still have to arm all nmethod entry barriers. They are needed for adding oop 3121 // constants to the SATB snapshot. Full GC does not need nmethods to be armed. 3122 if (!CodeCache::is_gc_marking_cycle_active()) { 3123 CodeCache::on_gc_marking_cycle_start(); 3124 } 3125 if (concurrent_mark_start) { 3126 CodeCache::arm_all_nmethods(); 3127 } 3128 } 3129 3130 void G1CollectedHeap::finish_codecache_marking_cycle() { 3131 CodeCache::on_gc_marking_cycle_finish(); 3132 CodeCache::arm_all_nmethods(); 3133 }