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