1 /* 2 * Copyright (c) 2023, Oracle and/or its affiliates. All rights reserved. 3 * Copyright (c) 2013, 2022, Red Hat, Inc. All rights reserved. 4 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 5 * 6 * This code is free software; you can redistribute it and/or modify it 7 * under the terms of the GNU General Public License version 2 only, as 8 * published by the Free Software Foundation. 9 * 10 * This code is distributed in the hope that it will be useful, but WITHOUT 11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 13 * version 2 for more details (a copy is included in the LICENSE file that 14 * accompanied this code). 15 * 16 * You should have received a copy of the GNU General Public License version 17 * 2 along with this work; if not, write to the Free Software Foundation, 18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 19 * 20 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 21 * or visit www.oracle.com if you need additional information or have any 22 * questions. 23 * 24 */ 25 26 #include "precompiled.hpp" 27 #include "memory/allocation.hpp" 28 #include "memory/universe.hpp" 29 30 #include "gc/shared/classUnloadingContext.hpp" 31 #include "gc/shared/gcArguments.hpp" 32 #include "gc/shared/gcTimer.hpp" 33 #include "gc/shared/gcTraceTime.inline.hpp" 34 #include "gc/shared/locationPrinter.inline.hpp" 35 #include "gc/shared/memAllocator.hpp" 36 #include "gc/shared/plab.hpp" 37 #include "gc/shared/tlab_globals.hpp" 38 39 #include "gc/shenandoah/shenandoahBarrierSet.hpp" 40 #include "gc/shenandoah/shenandoahClosures.inline.hpp" 41 #include "gc/shenandoah/shenandoahCollectionSet.hpp" 42 #include "gc/shenandoah/shenandoahCollectorPolicy.hpp" 43 #include "gc/shenandoah/shenandoahConcurrentMark.hpp" 44 #include "gc/shenandoah/shenandoahMarkingContext.inline.hpp" 45 #include "gc/shenandoah/shenandoahControlThread.hpp" 46 #include "gc/shenandoah/shenandoahFreeSet.hpp" 47 #include "gc/shenandoah/shenandoahPhaseTimings.hpp" 48 #include "gc/shenandoah/shenandoahHeap.inline.hpp" 49 #include "gc/shenandoah/shenandoahHeapRegion.inline.hpp" 50 #include "gc/shenandoah/shenandoahHeapRegionSet.hpp" 51 #include "gc/shenandoah/shenandoahInitLogger.hpp" 52 #include "gc/shenandoah/shenandoahMarkingContext.inline.hpp" 53 #include "gc/shenandoah/shenandoahMemoryPool.hpp" 54 #include "gc/shenandoah/shenandoahMetrics.hpp" 55 #include "gc/shenandoah/shenandoahMonitoringSupport.hpp" 56 #include "gc/shenandoah/shenandoahOopClosures.inline.hpp" 57 #include "gc/shenandoah/shenandoahPacer.inline.hpp" 58 #include "gc/shenandoah/shenandoahPadding.hpp" 59 #include "gc/shenandoah/shenandoahParallelCleaning.inline.hpp" 60 #include "gc/shenandoah/shenandoahReferenceProcessor.hpp" 61 #include "gc/shenandoah/shenandoahRootProcessor.inline.hpp" 62 #include "gc/shenandoah/shenandoahSTWMark.hpp" 63 #include "gc/shenandoah/shenandoahUtils.hpp" 64 #include "gc/shenandoah/shenandoahVerifier.hpp" 65 #include "gc/shenandoah/shenandoahCodeRoots.hpp" 66 #include "gc/shenandoah/shenandoahVMOperations.hpp" 67 #include "gc/shenandoah/shenandoahWorkGroup.hpp" 68 #include "gc/shenandoah/shenandoahWorkerPolicy.hpp" 69 #include "gc/shenandoah/mode/shenandoahIUMode.hpp" 70 #include "gc/shenandoah/mode/shenandoahPassiveMode.hpp" 71 #include "gc/shenandoah/mode/shenandoahSATBMode.hpp" 72 #if INCLUDE_JFR 73 #include "gc/shenandoah/shenandoahJfrSupport.hpp" 74 #endif 75 76 #include "classfile/systemDictionary.hpp" 77 #include "code/codeCache.hpp" 78 #include "memory/classLoaderMetaspace.hpp" 79 #include "memory/metaspaceUtils.hpp" 80 #include "oops/compressedOops.inline.hpp" 81 #include "prims/jvmtiTagMap.hpp" 82 #include "runtime/atomic.hpp" 83 #include "runtime/globals.hpp" 84 #include "runtime/interfaceSupport.inline.hpp" 85 #include "runtime/java.hpp" 86 #include "runtime/orderAccess.hpp" 87 #include "runtime/safepointMechanism.hpp" 88 #include "runtime/vmThread.hpp" 89 #include "services/mallocTracker.hpp" 90 #include "services/memTracker.hpp" 91 #include "utilities/events.hpp" 92 #include "utilities/powerOfTwo.hpp" 93 94 class ShenandoahPretouchHeapTask : public WorkerTask { 95 private: 96 ShenandoahRegionIterator _regions; 97 const size_t _page_size; 98 public: 99 ShenandoahPretouchHeapTask(size_t page_size) : 100 WorkerTask("Shenandoah Pretouch Heap"), 101 _page_size(page_size) {} 102 103 virtual void work(uint worker_id) { 104 ShenandoahHeapRegion* r = _regions.next(); 105 while (r != nullptr) { 106 if (r->is_committed()) { 107 os::pretouch_memory(r->bottom(), r->end(), _page_size); 108 } 109 r = _regions.next(); 110 } 111 } 112 }; 113 114 class ShenandoahPretouchBitmapTask : public WorkerTask { 115 private: 116 ShenandoahRegionIterator _regions; 117 char* _bitmap_base; 118 const size_t _bitmap_size; 119 const size_t _page_size; 120 public: 121 ShenandoahPretouchBitmapTask(char* bitmap_base, size_t bitmap_size, size_t page_size) : 122 WorkerTask("Shenandoah Pretouch Bitmap"), 123 _bitmap_base(bitmap_base), 124 _bitmap_size(bitmap_size), 125 _page_size(page_size) {} 126 127 virtual void work(uint worker_id) { 128 ShenandoahHeapRegion* r = _regions.next(); 129 while (r != nullptr) { 130 size_t start = r->index() * ShenandoahHeapRegion::region_size_bytes() / MarkBitMap::heap_map_factor(); 131 size_t end = (r->index() + 1) * ShenandoahHeapRegion::region_size_bytes() / MarkBitMap::heap_map_factor(); 132 assert (end <= _bitmap_size, "end is sane: " SIZE_FORMAT " < " SIZE_FORMAT, end, _bitmap_size); 133 134 if (r->is_committed()) { 135 os::pretouch_memory(_bitmap_base + start, _bitmap_base + end, _page_size); 136 } 137 138 r = _regions.next(); 139 } 140 } 141 }; 142 143 jint ShenandoahHeap::initialize() { 144 // 145 // Figure out heap sizing 146 // 147 148 size_t init_byte_size = InitialHeapSize; 149 size_t min_byte_size = MinHeapSize; 150 size_t max_byte_size = MaxHeapSize; 151 size_t heap_alignment = HeapAlignment; 152 153 size_t reg_size_bytes = ShenandoahHeapRegion::region_size_bytes(); 154 155 Universe::check_alignment(max_byte_size, reg_size_bytes, "Shenandoah heap"); 156 Universe::check_alignment(init_byte_size, reg_size_bytes, "Shenandoah heap"); 157 158 _num_regions = ShenandoahHeapRegion::region_count(); 159 assert(_num_regions == (max_byte_size / reg_size_bytes), 160 "Regions should cover entire heap exactly: " SIZE_FORMAT " != " SIZE_FORMAT "/" SIZE_FORMAT, 161 _num_regions, max_byte_size, reg_size_bytes); 162 163 // Now we know the number of regions, initialize the heuristics. 164 initialize_heuristics(); 165 166 size_t num_committed_regions = init_byte_size / reg_size_bytes; 167 num_committed_regions = MIN2(num_committed_regions, _num_regions); 168 assert(num_committed_regions <= _num_regions, "sanity"); 169 _initial_size = num_committed_regions * reg_size_bytes; 170 171 size_t num_min_regions = min_byte_size / reg_size_bytes; 172 num_min_regions = MIN2(num_min_regions, _num_regions); 173 assert(num_min_regions <= _num_regions, "sanity"); 174 _minimum_size = num_min_regions * reg_size_bytes; 175 176 // Default to max heap size. 177 _soft_max_size = _num_regions * reg_size_bytes; 178 179 _committed = _initial_size; 180 181 size_t heap_page_size = UseLargePages ? os::large_page_size() : os::vm_page_size(); 182 size_t bitmap_page_size = UseLargePages ? os::large_page_size() : os::vm_page_size(); 183 size_t region_page_size = UseLargePages ? os::large_page_size() : os::vm_page_size(); 184 185 // 186 // Reserve and commit memory for heap 187 // 188 189 ReservedHeapSpace heap_rs = Universe::reserve_heap(max_byte_size, heap_alignment); 190 initialize_reserved_region(heap_rs); 191 _heap_region = MemRegion((HeapWord*)heap_rs.base(), heap_rs.size() / HeapWordSize); 192 _heap_region_special = heap_rs.special(); 193 194 assert((((size_t) base()) & ShenandoahHeapRegion::region_size_bytes_mask()) == 0, 195 "Misaligned heap: " PTR_FORMAT, p2i(base())); 196 197 #if SHENANDOAH_OPTIMIZED_MARKTASK 198 // The optimized ShenandoahMarkTask takes some bits away from the full object bits. 199 // Fail if we ever attempt to address more than we can. 200 if ((uintptr_t)heap_rs.end() >= ShenandoahMarkTask::max_addressable()) { 201 FormatBuffer<512> buf("Shenandoah reserved [" PTR_FORMAT ", " PTR_FORMAT") for the heap, \n" 202 "but max object address is " PTR_FORMAT ". Try to reduce heap size, or try other \n" 203 "VM options that allocate heap at lower addresses (HeapBaseMinAddress, AllocateHeapAt, etc).", 204 p2i(heap_rs.base()), p2i(heap_rs.end()), ShenandoahMarkTask::max_addressable()); 205 vm_exit_during_initialization("Fatal Error", buf); 206 } 207 #endif 208 209 ReservedSpace sh_rs = heap_rs.first_part(max_byte_size); 210 if (!_heap_region_special) { 211 os::commit_memory_or_exit(sh_rs.base(), _initial_size, heap_alignment, false, 212 "Cannot commit heap memory"); 213 } 214 215 // 216 // Reserve and commit memory for bitmap(s) 217 // 218 219 _bitmap_size = ShenandoahMarkBitMap::compute_size(heap_rs.size()); 220 _bitmap_size = align_up(_bitmap_size, bitmap_page_size); 221 222 size_t bitmap_bytes_per_region = reg_size_bytes / ShenandoahMarkBitMap::heap_map_factor(); 223 224 guarantee(bitmap_bytes_per_region != 0, 225 "Bitmap bytes per region should not be zero"); 226 guarantee(is_power_of_2(bitmap_bytes_per_region), 227 "Bitmap bytes per region should be power of two: " SIZE_FORMAT, bitmap_bytes_per_region); 228 229 if (bitmap_page_size > bitmap_bytes_per_region) { 230 _bitmap_regions_per_slice = bitmap_page_size / bitmap_bytes_per_region; 231 _bitmap_bytes_per_slice = bitmap_page_size; 232 } else { 233 _bitmap_regions_per_slice = 1; 234 _bitmap_bytes_per_slice = bitmap_bytes_per_region; 235 } 236 237 guarantee(_bitmap_regions_per_slice >= 1, 238 "Should have at least one region per slice: " SIZE_FORMAT, 239 _bitmap_regions_per_slice); 240 241 guarantee(((_bitmap_bytes_per_slice) % bitmap_page_size) == 0, 242 "Bitmap slices should be page-granular: bps = " SIZE_FORMAT ", page size = " SIZE_FORMAT, 243 _bitmap_bytes_per_slice, bitmap_page_size); 244 245 ReservedSpace bitmap(_bitmap_size, bitmap_page_size); 246 MemTracker::record_virtual_memory_type(bitmap.base(), mtGC); 247 _bitmap_region = MemRegion((HeapWord*) bitmap.base(), bitmap.size() / HeapWordSize); 248 _bitmap_region_special = bitmap.special(); 249 250 size_t bitmap_init_commit = _bitmap_bytes_per_slice * 251 align_up(num_committed_regions, _bitmap_regions_per_slice) / _bitmap_regions_per_slice; 252 bitmap_init_commit = MIN2(_bitmap_size, bitmap_init_commit); 253 if (!_bitmap_region_special) { 254 os::commit_memory_or_exit((char *) _bitmap_region.start(), bitmap_init_commit, bitmap_page_size, false, 255 "Cannot commit bitmap memory"); 256 } 257 258 _marking_context = new ShenandoahMarkingContext(_heap_region, _bitmap_region, _num_regions, _max_workers); 259 260 if (ShenandoahVerify) { 261 ReservedSpace verify_bitmap(_bitmap_size, bitmap_page_size); 262 if (!verify_bitmap.special()) { 263 os::commit_memory_or_exit(verify_bitmap.base(), verify_bitmap.size(), bitmap_page_size, false, 264 "Cannot commit verification bitmap memory"); 265 } 266 MemTracker::record_virtual_memory_type(verify_bitmap.base(), mtGC); 267 MemRegion verify_bitmap_region = MemRegion((HeapWord *) verify_bitmap.base(), verify_bitmap.size() / HeapWordSize); 268 _verification_bit_map.initialize(_heap_region, verify_bitmap_region); 269 _verifier = new ShenandoahVerifier(this, &_verification_bit_map); 270 } 271 272 // Reserve aux bitmap for use in object_iterate(). We don't commit it here. 273 ReservedSpace aux_bitmap(_bitmap_size, bitmap_page_size); 274 MemTracker::record_virtual_memory_type(aux_bitmap.base(), mtGC); 275 _aux_bitmap_region = MemRegion((HeapWord*) aux_bitmap.base(), aux_bitmap.size() / HeapWordSize); 276 _aux_bitmap_region_special = aux_bitmap.special(); 277 _aux_bit_map.initialize(_heap_region, _aux_bitmap_region); 278 279 // 280 // Create regions and region sets 281 // 282 size_t region_align = align_up(sizeof(ShenandoahHeapRegion), SHENANDOAH_CACHE_LINE_SIZE); 283 size_t region_storage_size = align_up(region_align * _num_regions, region_page_size); 284 region_storage_size = align_up(region_storage_size, os::vm_allocation_granularity()); 285 286 ReservedSpace region_storage(region_storage_size, region_page_size); 287 MemTracker::record_virtual_memory_type(region_storage.base(), mtGC); 288 if (!region_storage.special()) { 289 os::commit_memory_or_exit(region_storage.base(), region_storage_size, region_page_size, false, 290 "Cannot commit region memory"); 291 } 292 293 // Try to fit the collection set bitmap at lower addresses. This optimizes code generation for cset checks. 294 // Go up until a sensible limit (subject to encoding constraints) and try to reserve the space there. 295 // If not successful, bite a bullet and allocate at whatever address. 296 { 297 size_t cset_align = MAX2<size_t>(os::vm_page_size(), os::vm_allocation_granularity()); 298 size_t cset_size = align_up(((size_t) sh_rs.base() + sh_rs.size()) >> ShenandoahHeapRegion::region_size_bytes_shift(), cset_align); 299 300 uintptr_t min = round_up_power_of_2(cset_align); 301 uintptr_t max = (1u << 30u); 302 303 for (uintptr_t addr = min; addr <= max; addr <<= 1u) { 304 char* req_addr = (char*)addr; 305 assert(is_aligned(req_addr, cset_align), "Should be aligned"); 306 ReservedSpace cset_rs(cset_size, cset_align, os::vm_page_size(), req_addr); 307 if (cset_rs.is_reserved()) { 308 assert(cset_rs.base() == req_addr, "Allocated where requested: " PTR_FORMAT ", " PTR_FORMAT, p2i(cset_rs.base()), addr); 309 _collection_set = new ShenandoahCollectionSet(this, cset_rs, sh_rs.base()); 310 break; 311 } 312 } 313 314 if (_collection_set == nullptr) { 315 ReservedSpace cset_rs(cset_size, cset_align, os::vm_page_size()); 316 _collection_set = new ShenandoahCollectionSet(this, cset_rs, sh_rs.base()); 317 } 318 } 319 320 _regions = NEW_C_HEAP_ARRAY(ShenandoahHeapRegion*, _num_regions, mtGC); 321 _free_set = new ShenandoahFreeSet(this, _num_regions); 322 323 { 324 ShenandoahHeapLocker locker(lock()); 325 326 for (size_t i = 0; i < _num_regions; i++) { 327 HeapWord* start = (HeapWord*)sh_rs.base() + ShenandoahHeapRegion::region_size_words() * i; 328 bool is_committed = i < num_committed_regions; 329 void* loc = region_storage.base() + i * region_align; 330 331 ShenandoahHeapRegion* r = new (loc) ShenandoahHeapRegion(start, i, is_committed); 332 assert(is_aligned(r, SHENANDOAH_CACHE_LINE_SIZE), "Sanity"); 333 334 _marking_context->initialize_top_at_mark_start(r); 335 _regions[i] = r; 336 assert(!collection_set()->is_in(i), "New region should not be in collection set"); 337 } 338 339 // Initialize to complete 340 _marking_context->mark_complete(); 341 342 _free_set->rebuild(); 343 } 344 345 if (AlwaysPreTouch) { 346 // For NUMA, it is important to pre-touch the storage under bitmaps with worker threads, 347 // before initialize() below zeroes it with initializing thread. For any given region, 348 // we touch the region and the corresponding bitmaps from the same thread. 349 ShenandoahPushWorkerScope scope(workers(), _max_workers, false); 350 351 _pretouch_heap_page_size = heap_page_size; 352 _pretouch_bitmap_page_size = bitmap_page_size; 353 354 #ifdef LINUX 355 // UseTransparentHugePages would madvise that backing memory can be coalesced into huge 356 // pages. But, the kernel needs to know that every small page is used, in order to coalesce 357 // them into huge one. Therefore, we need to pretouch with smaller pages. 358 if (UseTransparentHugePages) { 359 _pretouch_heap_page_size = (size_t)os::vm_page_size(); 360 _pretouch_bitmap_page_size = (size_t)os::vm_page_size(); 361 } 362 #endif 363 364 // OS memory managers may want to coalesce back-to-back pages. Make their jobs 365 // simpler by pre-touching continuous spaces (heap and bitmap) separately. 366 367 ShenandoahPretouchBitmapTask bcl(bitmap.base(), _bitmap_size, _pretouch_bitmap_page_size); 368 _workers->run_task(&bcl); 369 370 ShenandoahPretouchHeapTask hcl(_pretouch_heap_page_size); 371 _workers->run_task(&hcl); 372 } 373 374 // 375 // Initialize the rest of GC subsystems 376 // 377 378 _liveness_cache = NEW_C_HEAP_ARRAY(ShenandoahLiveData*, _max_workers, mtGC); 379 for (uint worker = 0; worker < _max_workers; worker++) { 380 _liveness_cache[worker] = NEW_C_HEAP_ARRAY(ShenandoahLiveData, _num_regions, mtGC); 381 Copy::fill_to_bytes(_liveness_cache[worker], _num_regions * sizeof(ShenandoahLiveData)); 382 } 383 384 // There should probably be Shenandoah-specific options for these, 385 // just as there are G1-specific options. 386 { 387 ShenandoahSATBMarkQueueSet& satbqs = ShenandoahBarrierSet::satb_mark_queue_set(); 388 satbqs.set_process_completed_buffers_threshold(20); // G1SATBProcessCompletedThreshold 389 satbqs.set_buffer_enqueue_threshold_percentage(60); // G1SATBBufferEnqueueingThresholdPercent 390 } 391 392 _monitoring_support = new ShenandoahMonitoringSupport(this); 393 _phase_timings = new ShenandoahPhaseTimings(max_workers()); 394 ShenandoahCodeRoots::initialize(); 395 396 if (ShenandoahPacing) { 397 _pacer = new ShenandoahPacer(this); 398 _pacer->setup_for_idle(); 399 } else { 400 _pacer = nullptr; 401 } 402 403 _control_thread = new ShenandoahControlThread(); 404 405 ShenandoahInitLogger::print(); 406 407 return JNI_OK; 408 } 409 410 void ShenandoahHeap::initialize_mode() { 411 if (ShenandoahGCMode != nullptr) { 412 if (strcmp(ShenandoahGCMode, "satb") == 0) { 413 _gc_mode = new ShenandoahSATBMode(); 414 } else if (strcmp(ShenandoahGCMode, "iu") == 0) { 415 _gc_mode = new ShenandoahIUMode(); 416 } else if (strcmp(ShenandoahGCMode, "passive") == 0) { 417 _gc_mode = new ShenandoahPassiveMode(); 418 } else { 419 vm_exit_during_initialization("Unknown -XX:ShenandoahGCMode option"); 420 } 421 } else { 422 vm_exit_during_initialization("Unknown -XX:ShenandoahGCMode option (null)"); 423 } 424 _gc_mode->initialize_flags(); 425 if (_gc_mode->is_diagnostic() && !UnlockDiagnosticVMOptions) { 426 vm_exit_during_initialization( 427 err_msg("GC mode \"%s\" is diagnostic, and must be enabled via -XX:+UnlockDiagnosticVMOptions.", 428 _gc_mode->name())); 429 } 430 if (_gc_mode->is_experimental() && !UnlockExperimentalVMOptions) { 431 vm_exit_during_initialization( 432 err_msg("GC mode \"%s\" is experimental, and must be enabled via -XX:+UnlockExperimentalVMOptions.", 433 _gc_mode->name())); 434 } 435 } 436 437 void ShenandoahHeap::initialize_heuristics() { 438 assert(_gc_mode != nullptr, "Must be initialized"); 439 _heuristics = _gc_mode->initialize_heuristics(); 440 441 if (_heuristics->is_diagnostic() && !UnlockDiagnosticVMOptions) { 442 vm_exit_during_initialization( 443 err_msg("Heuristics \"%s\" is diagnostic, and must be enabled via -XX:+UnlockDiagnosticVMOptions.", 444 _heuristics->name())); 445 } 446 if (_heuristics->is_experimental() && !UnlockExperimentalVMOptions) { 447 vm_exit_during_initialization( 448 err_msg("Heuristics \"%s\" is experimental, and must be enabled via -XX:+UnlockExperimentalVMOptions.", 449 _heuristics->name())); 450 } 451 } 452 453 #ifdef _MSC_VER 454 #pragma warning( push ) 455 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list 456 #endif 457 458 ShenandoahHeap::ShenandoahHeap(ShenandoahCollectorPolicy* policy) : 459 CollectedHeap(), 460 _initial_size(0), 461 _used(0), 462 _committed(0), 463 _bytes_allocated_since_gc_start(0), 464 _max_workers(MAX2(ConcGCThreads, ParallelGCThreads)), 465 _workers(nullptr), 466 _safepoint_workers(nullptr), 467 _heap_region_special(false), 468 _num_regions(0), 469 _regions(nullptr), 470 _update_refs_iterator(this), 471 _gc_state_changed(false), 472 _control_thread(nullptr), 473 _shenandoah_policy(policy), 474 _gc_mode(nullptr), 475 _heuristics(nullptr), 476 _free_set(nullptr), 477 _pacer(nullptr), 478 _verifier(nullptr), 479 _phase_timings(nullptr), 480 _monitoring_support(nullptr), 481 _memory_pool(nullptr), 482 _stw_memory_manager("Shenandoah Pauses"), 483 _cycle_memory_manager("Shenandoah Cycles"), 484 _gc_timer(new ConcurrentGCTimer()), 485 _soft_ref_policy(), 486 _log_min_obj_alignment_in_bytes(LogMinObjAlignmentInBytes), 487 _ref_processor(new ShenandoahReferenceProcessor(MAX2(_max_workers, 1U))), 488 _marking_context(nullptr), 489 _bitmap_size(0), 490 _bitmap_regions_per_slice(0), 491 _bitmap_bytes_per_slice(0), 492 _bitmap_region_special(false), 493 _aux_bitmap_region_special(false), 494 _liveness_cache(nullptr), 495 _collection_set(nullptr) 496 { 497 // Initialize GC mode early, so we can adjust barrier support 498 initialize_mode(); 499 BarrierSet::set_barrier_set(new ShenandoahBarrierSet(this)); 500 501 _max_workers = MAX2(_max_workers, 1U); 502 _workers = new ShenandoahWorkerThreads("Shenandoah GC Threads", _max_workers); 503 if (_workers == nullptr) { 504 vm_exit_during_initialization("Failed necessary allocation."); 505 } else { 506 _workers->initialize_workers(); 507 } 508 509 if (ParallelGCThreads > 1) { 510 _safepoint_workers = new ShenandoahWorkerThreads("Safepoint Cleanup Thread", 511 ParallelGCThreads); 512 _safepoint_workers->initialize_workers(); 513 } 514 } 515 516 #ifdef _MSC_VER 517 #pragma warning( pop ) 518 #endif 519 520 class ShenandoahResetBitmapTask : public WorkerTask { 521 private: 522 ShenandoahRegionIterator _regions; 523 524 public: 525 ShenandoahResetBitmapTask() : 526 WorkerTask("Shenandoah Reset Bitmap") {} 527 528 void work(uint worker_id) { 529 ShenandoahHeapRegion* region = _regions.next(); 530 ShenandoahHeap* heap = ShenandoahHeap::heap(); 531 ShenandoahMarkingContext* const ctx = heap->marking_context(); 532 while (region != nullptr) { 533 if (heap->is_bitmap_slice_committed(region)) { 534 ctx->clear_bitmap(region); 535 } 536 region = _regions.next(); 537 } 538 } 539 }; 540 541 void ShenandoahHeap::reset_mark_bitmap() { 542 assert_gc_workers(_workers->active_workers()); 543 mark_incomplete_marking_context(); 544 545 ShenandoahResetBitmapTask task; 546 _workers->run_task(&task); 547 } 548 549 void ShenandoahHeap::print_on(outputStream* st) const { 550 st->print_cr("Shenandoah Heap"); 551 st->print_cr(" " SIZE_FORMAT "%s max, " SIZE_FORMAT "%s soft max, " SIZE_FORMAT "%s committed, " SIZE_FORMAT "%s used", 552 byte_size_in_proper_unit(max_capacity()), proper_unit_for_byte_size(max_capacity()), 553 byte_size_in_proper_unit(soft_max_capacity()), proper_unit_for_byte_size(soft_max_capacity()), 554 byte_size_in_proper_unit(committed()), proper_unit_for_byte_size(committed()), 555 byte_size_in_proper_unit(used()), proper_unit_for_byte_size(used())); 556 st->print_cr(" " SIZE_FORMAT " x " SIZE_FORMAT"%s regions", 557 num_regions(), 558 byte_size_in_proper_unit(ShenandoahHeapRegion::region_size_bytes()), 559 proper_unit_for_byte_size(ShenandoahHeapRegion::region_size_bytes())); 560 561 st->print("Status: "); 562 if (has_forwarded_objects()) st->print("has forwarded objects, "); 563 if (is_concurrent_mark_in_progress()) st->print("marking, "); 564 if (is_evacuation_in_progress()) st->print("evacuating, "); 565 if (is_update_refs_in_progress()) st->print("updating refs, "); 566 if (is_degenerated_gc_in_progress()) st->print("degenerated gc, "); 567 if (is_full_gc_in_progress()) st->print("full gc, "); 568 if (is_full_gc_move_in_progress()) st->print("full gc move, "); 569 if (is_concurrent_weak_root_in_progress()) st->print("concurrent weak roots, "); 570 if (is_concurrent_strong_root_in_progress() && 571 !is_concurrent_weak_root_in_progress()) st->print("concurrent strong roots, "); 572 573 if (cancelled_gc()) { 574 st->print("cancelled"); 575 } else { 576 st->print("not cancelled"); 577 } 578 st->cr(); 579 580 st->print_cr("Reserved region:"); 581 st->print_cr(" - [" PTR_FORMAT ", " PTR_FORMAT ") ", 582 p2i(reserved_region().start()), 583 p2i(reserved_region().end())); 584 585 ShenandoahCollectionSet* cset = collection_set(); 586 st->print_cr("Collection set:"); 587 if (cset != nullptr) { 588 st->print_cr(" - map (vanilla): " PTR_FORMAT, p2i(cset->map_address())); 589 st->print_cr(" - map (biased): " PTR_FORMAT, p2i(cset->biased_map_address())); 590 } else { 591 st->print_cr(" (null)"); 592 } 593 594 st->cr(); 595 MetaspaceUtils::print_on(st); 596 597 if (Verbose) { 598 st->cr(); 599 print_heap_regions_on(st); 600 } 601 } 602 603 class ShenandoahInitWorkerGCLABClosure : public ThreadClosure { 604 public: 605 void do_thread(Thread* thread) { 606 assert(thread != nullptr, "Sanity"); 607 assert(thread->is_Worker_thread(), "Only worker thread expected"); 608 ShenandoahThreadLocalData::initialize_gclab(thread); 609 } 610 }; 611 612 void ShenandoahHeap::post_initialize() { 613 CollectedHeap::post_initialize(); 614 MutexLocker ml(Threads_lock); 615 616 ShenandoahInitWorkerGCLABClosure init_gclabs; 617 _workers->threads_do(&init_gclabs); 618 619 // gclab can not be initialized early during VM startup, as it can not determinate its max_size. 620 // Now, we will let WorkerThreads to initialize gclab when new worker is created. 621 _workers->set_initialize_gclab(); 622 if (_safepoint_workers != nullptr) { 623 _safepoint_workers->threads_do(&init_gclabs); 624 _safepoint_workers->set_initialize_gclab(); 625 } 626 627 _heuristics->initialize(); 628 629 JFR_ONLY(ShenandoahJFRSupport::register_jfr_type_serializers()); 630 } 631 632 size_t ShenandoahHeap::used() const { 633 return Atomic::load(&_used); 634 } 635 636 size_t ShenandoahHeap::committed() const { 637 return Atomic::load(&_committed); 638 } 639 640 void ShenandoahHeap::increase_committed(size_t bytes) { 641 shenandoah_assert_heaplocked_or_safepoint(); 642 _committed += bytes; 643 } 644 645 void ShenandoahHeap::decrease_committed(size_t bytes) { 646 shenandoah_assert_heaplocked_or_safepoint(); 647 _committed -= bytes; 648 } 649 650 void ShenandoahHeap::increase_used(size_t bytes) { 651 Atomic::add(&_used, bytes, memory_order_relaxed); 652 } 653 654 void ShenandoahHeap::set_used(size_t bytes) { 655 Atomic::store(&_used, bytes); 656 } 657 658 void ShenandoahHeap::decrease_used(size_t bytes) { 659 assert(used() >= bytes, "never decrease heap size by more than we've left"); 660 Atomic::sub(&_used, bytes, memory_order_relaxed); 661 } 662 663 void ShenandoahHeap::increase_allocated(size_t bytes) { 664 Atomic::add(&_bytes_allocated_since_gc_start, bytes, memory_order_relaxed); 665 } 666 667 void ShenandoahHeap::notify_mutator_alloc_words(size_t words, bool waste) { 668 size_t bytes = words * HeapWordSize; 669 if (!waste) { 670 increase_used(bytes); 671 } 672 increase_allocated(bytes); 673 if (ShenandoahPacing) { 674 control_thread()->pacing_notify_alloc(words); 675 if (waste) { 676 pacer()->claim_for_alloc(words, true); 677 } 678 } 679 } 680 681 size_t ShenandoahHeap::capacity() const { 682 return committed(); 683 } 684 685 size_t ShenandoahHeap::max_capacity() const { 686 return _num_regions * ShenandoahHeapRegion::region_size_bytes(); 687 } 688 689 size_t ShenandoahHeap::soft_max_capacity() const { 690 size_t v = Atomic::load(&_soft_max_size); 691 assert(min_capacity() <= v && v <= max_capacity(), 692 "Should be in bounds: " SIZE_FORMAT " <= " SIZE_FORMAT " <= " SIZE_FORMAT, 693 min_capacity(), v, max_capacity()); 694 return v; 695 } 696 697 void ShenandoahHeap::set_soft_max_capacity(size_t v) { 698 assert(min_capacity() <= v && v <= max_capacity(), 699 "Should be in bounds: " SIZE_FORMAT " <= " SIZE_FORMAT " <= " SIZE_FORMAT, 700 min_capacity(), v, max_capacity()); 701 Atomic::store(&_soft_max_size, v); 702 } 703 704 size_t ShenandoahHeap::min_capacity() const { 705 return _minimum_size; 706 } 707 708 size_t ShenandoahHeap::initial_capacity() const { 709 return _initial_size; 710 } 711 712 bool ShenandoahHeap::is_in(const void* p) const { 713 HeapWord* heap_base = (HeapWord*) base(); 714 HeapWord* last_region_end = heap_base + ShenandoahHeapRegion::region_size_words() * num_regions(); 715 return p >= heap_base && p < last_region_end; 716 } 717 718 void ShenandoahHeap::op_uncommit(double shrink_before, size_t shrink_until) { 719 assert (ShenandoahUncommit, "should be enabled"); 720 721 // Application allocates from the beginning of the heap, and GC allocates at 722 // the end of it. It is more efficient to uncommit from the end, so that applications 723 // could enjoy the near committed regions. GC allocations are much less frequent, 724 // and therefore can accept the committing costs. 725 726 size_t count = 0; 727 for (size_t i = num_regions(); i > 0; i--) { // care about size_t underflow 728 ShenandoahHeapRegion* r = get_region(i - 1); 729 if (r->is_empty_committed() && (r->empty_time() < shrink_before)) { 730 ShenandoahHeapLocker locker(lock()); 731 if (r->is_empty_committed()) { 732 if (committed() < shrink_until + ShenandoahHeapRegion::region_size_bytes()) { 733 break; 734 } 735 736 r->make_uncommitted(); 737 count++; 738 } 739 } 740 SpinPause(); // allow allocators to take the lock 741 } 742 743 if (count > 0) { 744 control_thread()->notify_heap_changed(); 745 } 746 } 747 748 HeapWord* ShenandoahHeap::allocate_from_gclab_slow(Thread* thread, size_t size) { 749 // New object should fit the GCLAB size 750 size_t min_size = MAX2(size, PLAB::min_size()); 751 752 // Figure out size of new GCLAB, looking back at heuristics. Expand aggressively. 753 size_t new_size = ShenandoahThreadLocalData::gclab_size(thread) * 2; 754 new_size = MIN2(new_size, PLAB::max_size()); 755 new_size = MAX2(new_size, PLAB::min_size()); 756 757 // Record new heuristic value even if we take any shortcut. This captures 758 // the case when moderately-sized objects always take a shortcut. At some point, 759 // heuristics should catch up with them. 760 ShenandoahThreadLocalData::set_gclab_size(thread, new_size); 761 762 if (new_size < size) { 763 // New size still does not fit the object. Fall back to shared allocation. 764 // This avoids retiring perfectly good GCLABs, when we encounter a large object. 765 return nullptr; 766 } 767 768 // Retire current GCLAB, and allocate a new one. 769 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread); 770 gclab->retire(); 771 772 size_t actual_size = 0; 773 HeapWord* gclab_buf = allocate_new_gclab(min_size, new_size, &actual_size); 774 if (gclab_buf == nullptr) { 775 return nullptr; 776 } 777 778 assert (size <= actual_size, "allocation should fit"); 779 780 if (ZeroTLAB) { 781 // ..and clear it. 782 Copy::zero_to_words(gclab_buf, actual_size); 783 } else { 784 // ...and zap just allocated object. 785 #ifdef ASSERT 786 // Skip mangling the space corresponding to the object header to 787 // ensure that the returned space is not considered parsable by 788 // any concurrent GC thread. 789 size_t hdr_size = oopDesc::header_size(); 790 Copy::fill_to_words(gclab_buf + hdr_size, actual_size - hdr_size, badHeapWordVal); 791 #endif // ASSERT 792 } 793 gclab->set_buf(gclab_buf, actual_size); 794 return gclab->allocate(size); 795 } 796 797 HeapWord* ShenandoahHeap::allocate_new_tlab(size_t min_size, 798 size_t requested_size, 799 size_t* actual_size) { 800 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_tlab(min_size, requested_size); 801 HeapWord* res = allocate_memory(req); 802 if (res != nullptr) { 803 *actual_size = req.actual_size(); 804 } else { 805 *actual_size = 0; 806 } 807 return res; 808 } 809 810 HeapWord* ShenandoahHeap::allocate_new_gclab(size_t min_size, 811 size_t word_size, 812 size_t* actual_size) { 813 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_gclab(min_size, word_size); 814 HeapWord* res = allocate_memory(req); 815 if (res != nullptr) { 816 *actual_size = req.actual_size(); 817 } else { 818 *actual_size = 0; 819 } 820 return res; 821 } 822 823 HeapWord* ShenandoahHeap::allocate_memory(ShenandoahAllocRequest& req) { 824 intptr_t pacer_epoch = 0; 825 bool in_new_region = false; 826 HeapWord* result = nullptr; 827 828 if (req.is_mutator_alloc()) { 829 if (ShenandoahPacing) { 830 pacer()->pace_for_alloc(req.size()); 831 pacer_epoch = pacer()->epoch(); 832 } 833 834 if (!ShenandoahAllocFailureALot || !should_inject_alloc_failure()) { 835 result = allocate_memory_under_lock(req, in_new_region); 836 } 837 838 // Allocation failed, block until control thread reacted, then retry allocation. 839 // 840 // It might happen that one of the threads requesting allocation would unblock 841 // way later after GC happened, only to fail the second allocation, because 842 // other threads have already depleted the free storage. In this case, a better 843 // strategy is to try again, as long as GC makes progress (or until at least 844 // one full GC has completed). 845 size_t original_count = shenandoah_policy()->full_gc_count(); 846 while (result == nullptr 847 && (_progress_last_gc.is_set() || original_count == shenandoah_policy()->full_gc_count())) { 848 control_thread()->handle_alloc_failure(req); 849 result = allocate_memory_under_lock(req, in_new_region); 850 } 851 } else { 852 assert(req.is_gc_alloc(), "Can only accept GC allocs here"); 853 result = allocate_memory_under_lock(req, in_new_region); 854 // Do not call handle_alloc_failure() here, because we cannot block. 855 // The allocation failure would be handled by the LRB slowpath with handle_alloc_failure_evac(). 856 } 857 858 if (in_new_region) { 859 control_thread()->notify_heap_changed(); 860 } 861 862 if (result != nullptr) { 863 size_t requested = req.size(); 864 size_t actual = req.actual_size(); 865 866 assert (req.is_lab_alloc() || (requested == actual), 867 "Only LAB allocations are elastic: %s, requested = " SIZE_FORMAT ", actual = " SIZE_FORMAT, 868 ShenandoahAllocRequest::alloc_type_to_string(req.type()), requested, actual); 869 870 if (req.is_mutator_alloc()) { 871 notify_mutator_alloc_words(actual, false); 872 873 // If we requested more than we were granted, give the rest back to pacer. 874 // This only matters if we are in the same pacing epoch: do not try to unpace 875 // over the budget for the other phase. 876 if (ShenandoahPacing && (pacer_epoch > 0) && (requested > actual)) { 877 pacer()->unpace_for_alloc(pacer_epoch, requested - actual); 878 } 879 } else { 880 increase_used(actual*HeapWordSize); 881 } 882 } 883 884 return result; 885 } 886 887 HeapWord* ShenandoahHeap::allocate_memory_under_lock(ShenandoahAllocRequest& req, bool& in_new_region) { 888 ShenandoahHeapLocker locker(lock()); 889 return _free_set->allocate(req, in_new_region); 890 } 891 892 HeapWord* ShenandoahHeap::mem_allocate(size_t size, 893 bool* gc_overhead_limit_was_exceeded) { 894 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_shared(size); 895 return allocate_memory(req); 896 } 897 898 MetaWord* ShenandoahHeap::satisfy_failed_metadata_allocation(ClassLoaderData* loader_data, 899 size_t size, 900 Metaspace::MetadataType mdtype) { 901 MetaWord* result; 902 903 // Inform metaspace OOM to GC heuristics if class unloading is possible. 904 if (heuristics()->can_unload_classes()) { 905 ShenandoahHeuristics* h = heuristics(); 906 h->record_metaspace_oom(); 907 } 908 909 // Expand and retry allocation 910 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype); 911 if (result != nullptr) { 912 return result; 913 } 914 915 // Start full GC 916 collect(GCCause::_metadata_GC_clear_soft_refs); 917 918 // Retry allocation 919 result = loader_data->metaspace_non_null()->allocate(size, mdtype); 920 if (result != nullptr) { 921 return result; 922 } 923 924 // Expand and retry allocation 925 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype); 926 if (result != nullptr) { 927 return result; 928 } 929 930 // Out of memory 931 return nullptr; 932 } 933 934 class ShenandoahConcurrentEvacuateRegionObjectClosure : public ObjectClosure { 935 private: 936 ShenandoahHeap* const _heap; 937 Thread* const _thread; 938 public: 939 ShenandoahConcurrentEvacuateRegionObjectClosure(ShenandoahHeap* heap) : 940 _heap(heap), _thread(Thread::current()) {} 941 942 void do_object(oop p) { 943 shenandoah_assert_marked(nullptr, p); 944 if (!p->is_forwarded()) { 945 _heap->evacuate_object(p, _thread); 946 } 947 } 948 }; 949 950 class ShenandoahEvacuationTask : public WorkerTask { 951 private: 952 ShenandoahHeap* const _sh; 953 ShenandoahCollectionSet* const _cs; 954 bool _concurrent; 955 public: 956 ShenandoahEvacuationTask(ShenandoahHeap* sh, 957 ShenandoahCollectionSet* cs, 958 bool concurrent) : 959 WorkerTask("Shenandoah Evacuation"), 960 _sh(sh), 961 _cs(cs), 962 _concurrent(concurrent) 963 {} 964 965 void work(uint worker_id) { 966 if (_concurrent) { 967 ShenandoahConcurrentWorkerSession worker_session(worker_id); 968 ShenandoahSuspendibleThreadSetJoiner stsj; 969 ShenandoahEvacOOMScope oom_evac_scope; 970 do_work(); 971 } else { 972 ShenandoahParallelWorkerSession worker_session(worker_id); 973 ShenandoahEvacOOMScope oom_evac_scope; 974 do_work(); 975 } 976 } 977 978 private: 979 void do_work() { 980 ShenandoahConcurrentEvacuateRegionObjectClosure cl(_sh); 981 ShenandoahHeapRegion* r; 982 while ((r =_cs->claim_next()) != nullptr) { 983 assert(r->has_live(), "Region " SIZE_FORMAT " should have been reclaimed early", r->index()); 984 _sh->marked_object_iterate(r, &cl); 985 986 if (ShenandoahPacing) { 987 _sh->pacer()->report_evac(r->used() >> LogHeapWordSize); 988 } 989 990 if (_sh->check_cancelled_gc_and_yield(_concurrent)) { 991 break; 992 } 993 } 994 } 995 }; 996 997 void ShenandoahHeap::evacuate_collection_set(bool concurrent) { 998 ShenandoahEvacuationTask task(this, _collection_set, concurrent); 999 workers()->run_task(&task); 1000 } 1001 1002 void ShenandoahHeap::trash_cset_regions() { 1003 ShenandoahHeapLocker locker(lock()); 1004 1005 ShenandoahCollectionSet* set = collection_set(); 1006 ShenandoahHeapRegion* r; 1007 set->clear_current_index(); 1008 while ((r = set->next()) != nullptr) { 1009 r->make_trash(); 1010 } 1011 collection_set()->clear(); 1012 } 1013 1014 void ShenandoahHeap::print_heap_regions_on(outputStream* st) const { 1015 st->print_cr("Heap Regions:"); 1016 st->print_cr("Region state: EU=empty-uncommitted, EC=empty-committed, R=regular, H=humongous start, HP=pinned humongous start"); 1017 st->print_cr(" HC=humongous continuation, CS=collection set, TR=trash, P=pinned, CSP=pinned collection set"); 1018 st->print_cr("BTE=bottom/top/end, TAMS=top-at-mark-start"); 1019 st->print_cr("UWM=update watermark, U=used"); 1020 st->print_cr("T=TLAB allocs, G=GCLAB allocs"); 1021 st->print_cr("S=shared allocs, L=live data"); 1022 st->print_cr("CP=critical pins"); 1023 1024 for (size_t i = 0; i < num_regions(); i++) { 1025 get_region(i)->print_on(st); 1026 } 1027 } 1028 1029 void ShenandoahHeap::trash_humongous_region_at(ShenandoahHeapRegion* start) { 1030 assert(start->is_humongous_start(), "reclaim regions starting with the first one"); 1031 1032 oop humongous_obj = cast_to_oop(start->bottom()); 1033 size_t size = humongous_obj->size(); 1034 size_t required_regions = ShenandoahHeapRegion::required_regions(size * HeapWordSize); 1035 size_t index = start->index() + required_regions - 1; 1036 1037 assert(!start->has_live(), "liveness must be zero"); 1038 1039 for(size_t i = 0; i < required_regions; i++) { 1040 // Reclaim from tail. Otherwise, assertion fails when printing region to trace log, 1041 // as it expects that every region belongs to a humongous region starting with a humongous start region. 1042 ShenandoahHeapRegion* region = get_region(index --); 1043 1044 assert(region->is_humongous(), "expect correct humongous start or continuation"); 1045 assert(!region->is_cset(), "Humongous region should not be in collection set"); 1046 1047 region->make_trash_immediate(); 1048 } 1049 } 1050 1051 class ShenandoahCheckCleanGCLABClosure : public ThreadClosure { 1052 public: 1053 ShenandoahCheckCleanGCLABClosure() {} 1054 void do_thread(Thread* thread) { 1055 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread); 1056 assert(gclab != nullptr, "GCLAB should be initialized for %s", thread->name()); 1057 assert(gclab->words_remaining() == 0, "GCLAB should not need retirement"); 1058 } 1059 }; 1060 1061 class ShenandoahRetireGCLABClosure : public ThreadClosure { 1062 private: 1063 bool const _resize; 1064 public: 1065 ShenandoahRetireGCLABClosure(bool resize) : _resize(resize) {} 1066 void do_thread(Thread* thread) { 1067 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread); 1068 assert(gclab != nullptr, "GCLAB should be initialized for %s", thread->name()); 1069 gclab->retire(); 1070 if (_resize && ShenandoahThreadLocalData::gclab_size(thread) > 0) { 1071 ShenandoahThreadLocalData::set_gclab_size(thread, 0); 1072 } 1073 } 1074 }; 1075 1076 void ShenandoahHeap::labs_make_parsable() { 1077 assert(UseTLAB, "Only call with UseTLAB"); 1078 1079 ShenandoahRetireGCLABClosure cl(false); 1080 1081 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) { 1082 ThreadLocalAllocBuffer& tlab = t->tlab(); 1083 tlab.make_parsable(); 1084 cl.do_thread(t); 1085 } 1086 1087 workers()->threads_do(&cl); 1088 } 1089 1090 void ShenandoahHeap::tlabs_retire(bool resize) { 1091 assert(UseTLAB, "Only call with UseTLAB"); 1092 assert(!resize || ResizeTLAB, "Only call for resize when ResizeTLAB is enabled"); 1093 1094 ThreadLocalAllocStats stats; 1095 1096 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) { 1097 ThreadLocalAllocBuffer& tlab = t->tlab(); 1098 tlab.retire(&stats); 1099 if (resize) { 1100 tlab.resize(); 1101 } 1102 } 1103 1104 stats.publish(); 1105 1106 #ifdef ASSERT 1107 ShenandoahCheckCleanGCLABClosure cl; 1108 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) { 1109 cl.do_thread(t); 1110 } 1111 workers()->threads_do(&cl); 1112 #endif 1113 } 1114 1115 void ShenandoahHeap::gclabs_retire(bool resize) { 1116 assert(UseTLAB, "Only call with UseTLAB"); 1117 assert(!resize || ResizeTLAB, "Only call for resize when ResizeTLAB is enabled"); 1118 1119 ShenandoahRetireGCLABClosure cl(resize); 1120 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) { 1121 cl.do_thread(t); 1122 } 1123 workers()->threads_do(&cl); 1124 1125 if (safepoint_workers() != nullptr) { 1126 safepoint_workers()->threads_do(&cl); 1127 } 1128 } 1129 1130 // Returns size in bytes 1131 size_t ShenandoahHeap::unsafe_max_tlab_alloc(Thread *thread) const { 1132 // Return the max allowed size, and let the allocation path 1133 // figure out the safe size for current allocation. 1134 return ShenandoahHeapRegion::max_tlab_size_bytes(); 1135 } 1136 1137 size_t ShenandoahHeap::max_tlab_size() const { 1138 // Returns size in words 1139 return ShenandoahHeapRegion::max_tlab_size_words(); 1140 } 1141 1142 void ShenandoahHeap::collect(GCCause::Cause cause) { 1143 control_thread()->request_gc(cause); 1144 } 1145 1146 void ShenandoahHeap::do_full_collection(bool clear_all_soft_refs) { 1147 //assert(false, "Shouldn't need to do full collections"); 1148 } 1149 1150 HeapWord* ShenandoahHeap::block_start(const void* addr) const { 1151 ShenandoahHeapRegion* r = heap_region_containing(addr); 1152 if (r != nullptr) { 1153 return r->block_start(addr); 1154 } 1155 return nullptr; 1156 } 1157 1158 bool ShenandoahHeap::block_is_obj(const HeapWord* addr) const { 1159 ShenandoahHeapRegion* r = heap_region_containing(addr); 1160 return r->block_is_obj(addr); 1161 } 1162 1163 bool ShenandoahHeap::print_location(outputStream* st, void* addr) const { 1164 return BlockLocationPrinter<ShenandoahHeap>::print_location(st, addr); 1165 } 1166 1167 void ShenandoahHeap::prepare_for_verify() { 1168 if (SafepointSynchronize::is_at_safepoint() && UseTLAB) { 1169 labs_make_parsable(); 1170 } 1171 } 1172 1173 void ShenandoahHeap::gc_threads_do(ThreadClosure* tcl) const { 1174 tcl->do_thread(_control_thread); 1175 workers()->threads_do(tcl); 1176 if (_safepoint_workers != nullptr) { 1177 _safepoint_workers->threads_do(tcl); 1178 } 1179 } 1180 1181 void ShenandoahHeap::print_tracing_info() const { 1182 LogTarget(Info, gc, stats) lt; 1183 if (lt.is_enabled()) { 1184 ResourceMark rm; 1185 LogStream ls(lt); 1186 1187 phase_timings()->print_global_on(&ls); 1188 1189 ls.cr(); 1190 ls.cr(); 1191 1192 shenandoah_policy()->print_gc_stats(&ls); 1193 1194 ls.cr(); 1195 ls.cr(); 1196 } 1197 } 1198 1199 void ShenandoahHeap::verify(VerifyOption vo) { 1200 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) { 1201 if (ShenandoahVerify) { 1202 verifier()->verify_generic(vo); 1203 } else { 1204 // TODO: Consider allocating verification bitmaps on demand, 1205 // and turn this on unconditionally. 1206 } 1207 } 1208 } 1209 size_t ShenandoahHeap::tlab_capacity(Thread *thr) const { 1210 return _free_set->capacity(); 1211 } 1212 1213 class ObjectIterateScanRootClosure : public BasicOopIterateClosure { 1214 private: 1215 MarkBitMap* _bitmap; 1216 ShenandoahScanObjectStack* _oop_stack; 1217 ShenandoahHeap* const _heap; 1218 ShenandoahMarkingContext* const _marking_context; 1219 1220 template <class T> 1221 void do_oop_work(T* p) { 1222 T o = RawAccess<>::oop_load(p); 1223 if (!CompressedOops::is_null(o)) { 1224 oop obj = CompressedOops::decode_not_null(o); 1225 if (_heap->is_concurrent_weak_root_in_progress() && !_marking_context->is_marked(obj)) { 1226 // There may be dead oops in weak roots in concurrent root phase, do not touch them. 1227 return; 1228 } 1229 obj = ShenandoahBarrierSet::barrier_set()->load_reference_barrier(obj); 1230 1231 assert(oopDesc::is_oop(obj), "must be a valid oop"); 1232 if (!_bitmap->is_marked(obj)) { 1233 _bitmap->mark(obj); 1234 _oop_stack->push(obj); 1235 } 1236 } 1237 } 1238 public: 1239 ObjectIterateScanRootClosure(MarkBitMap* bitmap, ShenandoahScanObjectStack* oop_stack) : 1240 _bitmap(bitmap), _oop_stack(oop_stack), _heap(ShenandoahHeap::heap()), 1241 _marking_context(_heap->marking_context()) {} 1242 void do_oop(oop* p) { do_oop_work(p); } 1243 void do_oop(narrowOop* p) { do_oop_work(p); } 1244 }; 1245 1246 /* 1247 * This is public API, used in preparation of object_iterate(). 1248 * Since we don't do linear scan of heap in object_iterate() (see comment below), we don't 1249 * need to make the heap parsable. For Shenandoah-internal linear heap scans that we can 1250 * control, we call SH::tlabs_retire, SH::gclabs_retire. 1251 */ 1252 void ShenandoahHeap::ensure_parsability(bool retire_tlabs) { 1253 // No-op. 1254 } 1255 1256 /* 1257 * Iterates objects in the heap. This is public API, used for, e.g., heap dumping. 1258 * 1259 * We cannot safely iterate objects by doing a linear scan at random points in time. Linear 1260 * scanning needs to deal with dead objects, which may have dead Klass* pointers (e.g. 1261 * calling oopDesc::size() would crash) or dangling reference fields (crashes) etc. Linear 1262 * scanning therefore depends on having a valid marking bitmap to support it. However, we only 1263 * have a valid marking bitmap after successful marking. In particular, we *don't* have a valid 1264 * marking bitmap during marking, after aborted marking or during/after cleanup (when we just 1265 * wiped the bitmap in preparation for next marking). 1266 * 1267 * For all those reasons, we implement object iteration as a single marking traversal, reporting 1268 * objects as we mark+traverse through the heap, starting from GC roots. JVMTI IterateThroughHeap 1269 * is allowed to report dead objects, but is not required to do so. 1270 */ 1271 void ShenandoahHeap::object_iterate(ObjectClosure* cl) { 1272 // Reset bitmap 1273 if (!prepare_aux_bitmap_for_iteration()) 1274 return; 1275 1276 ShenandoahScanObjectStack oop_stack; 1277 ObjectIterateScanRootClosure oops(&_aux_bit_map, &oop_stack); 1278 // Seed the stack with root scan 1279 scan_roots_for_iteration(&oop_stack, &oops); 1280 1281 // Work through the oop stack to traverse heap 1282 while (! oop_stack.is_empty()) { 1283 oop obj = oop_stack.pop(); 1284 assert(oopDesc::is_oop(obj), "must be a valid oop"); 1285 cl->do_object(obj); 1286 obj->oop_iterate(&oops); 1287 } 1288 1289 assert(oop_stack.is_empty(), "should be empty"); 1290 // Reclaim bitmap 1291 reclaim_aux_bitmap_for_iteration(); 1292 } 1293 1294 bool ShenandoahHeap::prepare_aux_bitmap_for_iteration() { 1295 assert(SafepointSynchronize::is_at_safepoint(), "safe iteration is only available during safepoints"); 1296 1297 if (!_aux_bitmap_region_special && !os::commit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size(), false)) { 1298 log_warning(gc)("Could not commit native memory for auxiliary marking bitmap for heap iteration"); 1299 return false; 1300 } 1301 // Reset bitmap 1302 _aux_bit_map.clear(); 1303 return true; 1304 } 1305 1306 void ShenandoahHeap::scan_roots_for_iteration(ShenandoahScanObjectStack* oop_stack, ObjectIterateScanRootClosure* oops) { 1307 // Process GC roots according to current GC cycle 1308 // This populates the work stack with initial objects 1309 // It is important to relinquish the associated locks before diving 1310 // into heap dumper 1311 uint n_workers = safepoint_workers() != nullptr ? safepoint_workers()->active_workers() : 1; 1312 ShenandoahHeapIterationRootScanner rp(n_workers); 1313 rp.roots_do(oops); 1314 } 1315 1316 void ShenandoahHeap::reclaim_aux_bitmap_for_iteration() { 1317 if (!_aux_bitmap_region_special && !os::uncommit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size())) { 1318 log_warning(gc)("Could not uncommit native memory for auxiliary marking bitmap for heap iteration"); 1319 } 1320 } 1321 1322 // Closure for parallelly iterate objects 1323 class ShenandoahObjectIterateParScanClosure : public BasicOopIterateClosure { 1324 private: 1325 MarkBitMap* _bitmap; 1326 ShenandoahObjToScanQueue* _queue; 1327 ShenandoahHeap* const _heap; 1328 ShenandoahMarkingContext* const _marking_context; 1329 1330 template <class T> 1331 void do_oop_work(T* p) { 1332 T o = RawAccess<>::oop_load(p); 1333 if (!CompressedOops::is_null(o)) { 1334 oop obj = CompressedOops::decode_not_null(o); 1335 if (_heap->is_concurrent_weak_root_in_progress() && !_marking_context->is_marked(obj)) { 1336 // There may be dead oops in weak roots in concurrent root phase, do not touch them. 1337 return; 1338 } 1339 obj = ShenandoahBarrierSet::barrier_set()->load_reference_barrier(obj); 1340 1341 assert(oopDesc::is_oop(obj), "Must be a valid oop"); 1342 if (_bitmap->par_mark(obj)) { 1343 _queue->push(ShenandoahMarkTask(obj)); 1344 } 1345 } 1346 } 1347 public: 1348 ShenandoahObjectIterateParScanClosure(MarkBitMap* bitmap, ShenandoahObjToScanQueue* q) : 1349 _bitmap(bitmap), _queue(q), _heap(ShenandoahHeap::heap()), 1350 _marking_context(_heap->marking_context()) {} 1351 void do_oop(oop* p) { do_oop_work(p); } 1352 void do_oop(narrowOop* p) { do_oop_work(p); } 1353 }; 1354 1355 // Object iterator for parallel heap iteraion. 1356 // The root scanning phase happenes in construction as a preparation of 1357 // parallel marking queues. 1358 // Every worker processes it's own marking queue. work-stealing is used 1359 // to balance workload. 1360 class ShenandoahParallelObjectIterator : public ParallelObjectIteratorImpl { 1361 private: 1362 uint _num_workers; 1363 bool _init_ready; 1364 MarkBitMap* _aux_bit_map; 1365 ShenandoahHeap* _heap; 1366 ShenandoahScanObjectStack _roots_stack; // global roots stack 1367 ShenandoahObjToScanQueueSet* _task_queues; 1368 public: 1369 ShenandoahParallelObjectIterator(uint num_workers, MarkBitMap* bitmap) : 1370 _num_workers(num_workers), 1371 _init_ready(false), 1372 _aux_bit_map(bitmap), 1373 _heap(ShenandoahHeap::heap()) { 1374 // Initialize bitmap 1375 _init_ready = _heap->prepare_aux_bitmap_for_iteration(); 1376 if (!_init_ready) { 1377 return; 1378 } 1379 1380 ObjectIterateScanRootClosure oops(_aux_bit_map, &_roots_stack); 1381 _heap->scan_roots_for_iteration(&_roots_stack, &oops); 1382 1383 _init_ready = prepare_worker_queues(); 1384 } 1385 1386 ~ShenandoahParallelObjectIterator() { 1387 // Reclaim bitmap 1388 _heap->reclaim_aux_bitmap_for_iteration(); 1389 // Reclaim queue for workers 1390 if (_task_queues!= nullptr) { 1391 for (uint i = 0; i < _num_workers; ++i) { 1392 ShenandoahObjToScanQueue* q = _task_queues->queue(i); 1393 if (q != nullptr) { 1394 delete q; 1395 _task_queues->register_queue(i, nullptr); 1396 } 1397 } 1398 delete _task_queues; 1399 _task_queues = nullptr; 1400 } 1401 } 1402 1403 virtual void object_iterate(ObjectClosure* cl, uint worker_id) { 1404 if (_init_ready) { 1405 object_iterate_parallel(cl, worker_id, _task_queues); 1406 } 1407 } 1408 1409 private: 1410 // Divide global root_stack into worker queues 1411 bool prepare_worker_queues() { 1412 _task_queues = new ShenandoahObjToScanQueueSet((int) _num_workers); 1413 // Initialize queues for every workers 1414 for (uint i = 0; i < _num_workers; ++i) { 1415 ShenandoahObjToScanQueue* task_queue = new ShenandoahObjToScanQueue(); 1416 _task_queues->register_queue(i, task_queue); 1417 } 1418 // Divide roots among the workers. Assume that object referencing distribution 1419 // is related with root kind, use round-robin to make every worker have same chance 1420 // to process every kind of roots 1421 size_t roots_num = _roots_stack.size(); 1422 if (roots_num == 0) { 1423 // No work to do 1424 return false; 1425 } 1426 1427 for (uint j = 0; j < roots_num; j++) { 1428 uint stack_id = j % _num_workers; 1429 oop obj = _roots_stack.pop(); 1430 _task_queues->queue(stack_id)->push(ShenandoahMarkTask(obj)); 1431 } 1432 return true; 1433 } 1434 1435 void object_iterate_parallel(ObjectClosure* cl, 1436 uint worker_id, 1437 ShenandoahObjToScanQueueSet* queue_set) { 1438 assert(SafepointSynchronize::is_at_safepoint(), "safe iteration is only available during safepoints"); 1439 assert(queue_set != nullptr, "task queue must not be null"); 1440 1441 ShenandoahObjToScanQueue* q = queue_set->queue(worker_id); 1442 assert(q != nullptr, "object iterate queue must not be null"); 1443 1444 ShenandoahMarkTask t; 1445 ShenandoahObjectIterateParScanClosure oops(_aux_bit_map, q); 1446 1447 // Work through the queue to traverse heap. 1448 // Steal when there is no task in queue. 1449 while (q->pop(t) || queue_set->steal(worker_id, t)) { 1450 oop obj = t.obj(); 1451 assert(oopDesc::is_oop(obj), "must be a valid oop"); 1452 cl->do_object(obj); 1453 obj->oop_iterate(&oops); 1454 } 1455 assert(q->is_empty(), "should be empty"); 1456 } 1457 }; 1458 1459 ParallelObjectIteratorImpl* ShenandoahHeap::parallel_object_iterator(uint workers) { 1460 return new ShenandoahParallelObjectIterator(workers, &_aux_bit_map); 1461 } 1462 1463 // Keep alive an object that was loaded with AS_NO_KEEPALIVE. 1464 void ShenandoahHeap::keep_alive(oop obj) { 1465 if (is_concurrent_mark_in_progress() && (obj != nullptr)) { 1466 ShenandoahBarrierSet::barrier_set()->enqueue(obj); 1467 } 1468 } 1469 1470 void ShenandoahHeap::heap_region_iterate(ShenandoahHeapRegionClosure* blk) const { 1471 for (size_t i = 0; i < num_regions(); i++) { 1472 ShenandoahHeapRegion* current = get_region(i); 1473 blk->heap_region_do(current); 1474 } 1475 } 1476 1477 class ShenandoahParallelHeapRegionTask : public WorkerTask { 1478 private: 1479 ShenandoahHeap* const _heap; 1480 ShenandoahHeapRegionClosure* const _blk; 1481 1482 shenandoah_padding(0); 1483 volatile size_t _index; 1484 shenandoah_padding(1); 1485 1486 public: 1487 ShenandoahParallelHeapRegionTask(ShenandoahHeapRegionClosure* blk) : 1488 WorkerTask("Shenandoah Parallel Region Operation"), 1489 _heap(ShenandoahHeap::heap()), _blk(blk), _index(0) {} 1490 1491 void work(uint worker_id) { 1492 ShenandoahParallelWorkerSession worker_session(worker_id); 1493 size_t stride = ShenandoahParallelRegionStride; 1494 1495 size_t max = _heap->num_regions(); 1496 while (Atomic::load(&_index) < max) { 1497 size_t cur = Atomic::fetch_then_add(&_index, stride, memory_order_relaxed); 1498 size_t start = cur; 1499 size_t end = MIN2(cur + stride, max); 1500 if (start >= max) break; 1501 1502 for (size_t i = cur; i < end; i++) { 1503 ShenandoahHeapRegion* current = _heap->get_region(i); 1504 _blk->heap_region_do(current); 1505 } 1506 } 1507 } 1508 }; 1509 1510 void ShenandoahHeap::parallel_heap_region_iterate(ShenandoahHeapRegionClosure* blk) const { 1511 assert(blk->is_thread_safe(), "Only thread-safe closures here"); 1512 if (num_regions() > ShenandoahParallelRegionStride) { 1513 ShenandoahParallelHeapRegionTask task(blk); 1514 workers()->run_task(&task); 1515 } else { 1516 heap_region_iterate(blk); 1517 } 1518 } 1519 1520 class ShenandoahInitMarkUpdateRegionStateClosure : public ShenandoahHeapRegionClosure { 1521 private: 1522 ShenandoahMarkingContext* const _ctx; 1523 public: 1524 ShenandoahInitMarkUpdateRegionStateClosure() : _ctx(ShenandoahHeap::heap()->marking_context()) {} 1525 1526 void heap_region_do(ShenandoahHeapRegion* r) { 1527 assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->index()); 1528 if (r->is_active()) { 1529 // Check if region needs updating its TAMS. We have updated it already during concurrent 1530 // reset, so it is very likely we don't need to do another write here. 1531 if (_ctx->top_at_mark_start(r) != r->top()) { 1532 _ctx->capture_top_at_mark_start(r); 1533 } 1534 } else { 1535 assert(_ctx->top_at_mark_start(r) == r->top(), 1536 "Region " SIZE_FORMAT " should already have correct TAMS", r->index()); 1537 } 1538 } 1539 1540 bool is_thread_safe() { return true; } 1541 }; 1542 1543 class ShenandoahRendezvousClosure : public HandshakeClosure { 1544 public: 1545 inline ShenandoahRendezvousClosure() : HandshakeClosure("ShenandoahRendezvous") {} 1546 inline void do_thread(Thread* thread) {} 1547 }; 1548 1549 void ShenandoahHeap::rendezvous_threads() { 1550 ShenandoahRendezvousClosure cl; 1551 Handshake::execute(&cl); 1552 } 1553 1554 void ShenandoahHeap::recycle_trash() { 1555 free_set()->recycle_trash(); 1556 } 1557 1558 class ShenandoahResetUpdateRegionStateClosure : public ShenandoahHeapRegionClosure { 1559 private: 1560 ShenandoahMarkingContext* const _ctx; 1561 public: 1562 ShenandoahResetUpdateRegionStateClosure() : _ctx(ShenandoahHeap::heap()->marking_context()) {} 1563 1564 void heap_region_do(ShenandoahHeapRegion* r) { 1565 if (r->is_active()) { 1566 // Reset live data and set TAMS optimistically. We would recheck these under the pause 1567 // anyway to capture any updates that happened since now. 1568 r->clear_live_data(); 1569 _ctx->capture_top_at_mark_start(r); 1570 } 1571 } 1572 1573 bool is_thread_safe() { return true; } 1574 }; 1575 1576 void ShenandoahHeap::prepare_gc() { 1577 reset_mark_bitmap(); 1578 1579 ShenandoahResetUpdateRegionStateClosure cl; 1580 parallel_heap_region_iterate(&cl); 1581 } 1582 1583 class ShenandoahFinalMarkUpdateRegionStateClosure : public ShenandoahHeapRegionClosure { 1584 private: 1585 ShenandoahMarkingContext* const _ctx; 1586 ShenandoahHeapLock* const _lock; 1587 1588 public: 1589 ShenandoahFinalMarkUpdateRegionStateClosure() : 1590 _ctx(ShenandoahHeap::heap()->complete_marking_context()), _lock(ShenandoahHeap::heap()->lock()) {} 1591 1592 void heap_region_do(ShenandoahHeapRegion* r) { 1593 if (r->is_active()) { 1594 // All allocations past TAMS are implicitly live, adjust the region data. 1595 // Bitmaps/TAMS are swapped at this point, so we need to poll complete bitmap. 1596 HeapWord *tams = _ctx->top_at_mark_start(r); 1597 HeapWord *top = r->top(); 1598 if (top > tams) { 1599 r->increase_live_data_alloc_words(pointer_delta(top, tams)); 1600 } 1601 1602 // We are about to select the collection set, make sure it knows about 1603 // current pinning status. Also, this allows trashing more regions that 1604 // now have their pinning status dropped. 1605 if (r->is_pinned()) { 1606 if (r->pin_count() == 0) { 1607 ShenandoahHeapLocker locker(_lock); 1608 r->make_unpinned(); 1609 } 1610 } else { 1611 if (r->pin_count() > 0) { 1612 ShenandoahHeapLocker locker(_lock); 1613 r->make_pinned(); 1614 } 1615 } 1616 1617 // Remember limit for updating refs. It's guaranteed that we get no 1618 // from-space-refs written from here on. 1619 r->set_update_watermark_at_safepoint(r->top()); 1620 } else { 1621 assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->index()); 1622 assert(_ctx->top_at_mark_start(r) == r->top(), 1623 "Region " SIZE_FORMAT " should have correct TAMS", r->index()); 1624 } 1625 } 1626 1627 bool is_thread_safe() { return true; } 1628 }; 1629 1630 void ShenandoahHeap::prepare_regions_and_collection_set(bool concurrent) { 1631 assert(!is_full_gc_in_progress(), "Only for concurrent and degenerated GC"); 1632 { 1633 ShenandoahGCPhase phase(concurrent ? ShenandoahPhaseTimings::final_update_region_states : 1634 ShenandoahPhaseTimings::degen_gc_final_update_region_states); 1635 ShenandoahFinalMarkUpdateRegionStateClosure cl; 1636 parallel_heap_region_iterate(&cl); 1637 1638 assert_pinned_region_status(); 1639 } 1640 1641 { 1642 ShenandoahGCPhase phase(concurrent ? ShenandoahPhaseTimings::choose_cset : 1643 ShenandoahPhaseTimings::degen_gc_choose_cset); 1644 ShenandoahHeapLocker locker(lock()); 1645 _collection_set->clear(); 1646 heuristics()->choose_collection_set(_collection_set); 1647 } 1648 1649 { 1650 ShenandoahGCPhase phase(concurrent ? ShenandoahPhaseTimings::final_rebuild_freeset : 1651 ShenandoahPhaseTimings::degen_gc_final_rebuild_freeset); 1652 ShenandoahHeapLocker locker(lock()); 1653 _free_set->rebuild(); 1654 } 1655 } 1656 1657 void ShenandoahHeap::do_class_unloading() { 1658 _unloader.unload(); 1659 } 1660 1661 void ShenandoahHeap::stw_weak_refs(bool full_gc) { 1662 // Weak refs processing 1663 ShenandoahPhaseTimings::Phase phase = full_gc ? ShenandoahPhaseTimings::full_gc_weakrefs 1664 : ShenandoahPhaseTimings::degen_gc_weakrefs; 1665 ShenandoahTimingsTracker t(phase); 1666 ShenandoahGCWorkerPhase worker_phase(phase); 1667 ref_processor()->process_references(phase, workers(), false /* concurrent */); 1668 } 1669 1670 void ShenandoahHeap::prepare_update_heap_references(bool concurrent) { 1671 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint"); 1672 1673 // Evacuation is over, no GCLABs are needed anymore. GCLABs are under URWM, so we need to 1674 // make them parsable for update code to work correctly. Plus, we can compute new sizes 1675 // for future GCLABs here. 1676 if (UseTLAB) { 1677 ShenandoahGCPhase phase(concurrent ? 1678 ShenandoahPhaseTimings::init_update_refs_manage_gclabs : 1679 ShenandoahPhaseTimings::degen_gc_init_update_refs_manage_gclabs); 1680 gclabs_retire(ResizeTLAB); 1681 } 1682 1683 _update_refs_iterator.reset(); 1684 } 1685 1686 void ShenandoahHeap::propagate_gc_state_to_java_threads() { 1687 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Must be at Shenandoah safepoint"); 1688 if (_gc_state_changed) { 1689 _gc_state_changed = false; 1690 char state = gc_state(); 1691 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) { 1692 ShenandoahThreadLocalData::set_gc_state(t, state); 1693 } 1694 } 1695 } 1696 1697 void ShenandoahHeap::set_gc_state(uint mask, bool value) { 1698 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Must be at Shenandoah safepoint"); 1699 _gc_state.set_cond(mask, value); 1700 _gc_state_changed = true; 1701 } 1702 1703 void ShenandoahHeap::set_concurrent_mark_in_progress(bool in_progress) { 1704 assert(!has_forwarded_objects(), "Not expected before/after mark phase"); 1705 set_gc_state(MARKING, in_progress); 1706 ShenandoahBarrierSet::satb_mark_queue_set().set_active_all_threads(in_progress, !in_progress); 1707 } 1708 1709 void ShenandoahHeap::set_evacuation_in_progress(bool in_progress) { 1710 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Only call this at safepoint"); 1711 set_gc_state(EVACUATION, in_progress); 1712 } 1713 1714 void ShenandoahHeap::set_concurrent_strong_root_in_progress(bool in_progress) { 1715 if (in_progress) { 1716 _concurrent_strong_root_in_progress.set(); 1717 } else { 1718 _concurrent_strong_root_in_progress.unset(); 1719 } 1720 } 1721 1722 void ShenandoahHeap::set_concurrent_weak_root_in_progress(bool cond) { 1723 set_gc_state(WEAK_ROOTS, cond); 1724 } 1725 1726 GCTracer* ShenandoahHeap::tracer() { 1727 return shenandoah_policy()->tracer(); 1728 } 1729 1730 size_t ShenandoahHeap::tlab_used(Thread* thread) const { 1731 return _free_set->used(); 1732 } 1733 1734 bool ShenandoahHeap::try_cancel_gc() { 1735 jbyte prev = _cancelled_gc.cmpxchg(CANCELLED, CANCELLABLE); 1736 return prev == CANCELLABLE; 1737 } 1738 1739 void ShenandoahHeap::cancel_gc(GCCause::Cause cause) { 1740 if (try_cancel_gc()) { 1741 FormatBuffer<> msg("Cancelling GC: %s", GCCause::to_string(cause)); 1742 log_info(gc)("%s", msg.buffer()); 1743 Events::log(Thread::current(), "%s", msg.buffer()); 1744 } 1745 } 1746 1747 uint ShenandoahHeap::max_workers() { 1748 return _max_workers; 1749 } 1750 1751 void ShenandoahHeap::stop() { 1752 // The shutdown sequence should be able to terminate when GC is running. 1753 1754 // Step 0. Notify policy to disable event recording. 1755 _shenandoah_policy->record_shutdown(); 1756 1757 // Step 1. Notify control thread that we are in shutdown. 1758 // Note that we cannot do that with stop(), because stop() is blocking and waits for the actual shutdown. 1759 // Doing stop() here would wait for the normal GC cycle to complete, never falling through to cancel below. 1760 control_thread()->prepare_for_graceful_shutdown(); 1761 1762 // Step 2. Notify GC workers that we are cancelling GC. 1763 cancel_gc(GCCause::_shenandoah_stop_vm); 1764 1765 // Step 3. Wait until GC worker exits normally. 1766 control_thread()->stop(); 1767 } 1768 1769 void ShenandoahHeap::stw_unload_classes(bool full_gc) { 1770 if (!unload_classes()) return; 1771 ClassUnloadingContext ctx(_workers->active_workers(), 1772 true /* unregister_nmethods_during_purge */, 1773 false /* lock_codeblob_free_separately */); 1774 1775 // Unload classes and purge SystemDictionary. 1776 { 1777 ShenandoahPhaseTimings::Phase phase = full_gc ? 1778 ShenandoahPhaseTimings::full_gc_purge_class_unload : 1779 ShenandoahPhaseTimings::degen_gc_purge_class_unload; 1780 ShenandoahIsAliveSelector is_alive; 1781 { 1782 CodeCache::UnlinkingScope scope(is_alive.is_alive_closure()); 1783 ShenandoahGCPhase gc_phase(phase); 1784 ShenandoahGCWorkerPhase worker_phase(phase); 1785 bool unloading_occurred = SystemDictionary::do_unloading(gc_timer()); 1786 1787 uint num_workers = _workers->active_workers(); 1788 ShenandoahClassUnloadingTask unlink_task(phase, num_workers, unloading_occurred); 1789 _workers->run_task(&unlink_task); 1790 } 1791 // Release unloaded nmethods's memory. 1792 ClassUnloadingContext::context()->purge_and_free_nmethods(); 1793 } 1794 1795 { 1796 ShenandoahGCPhase phase(full_gc ? 1797 ShenandoahPhaseTimings::full_gc_purge_cldg : 1798 ShenandoahPhaseTimings::degen_gc_purge_cldg); 1799 ClassLoaderDataGraph::purge(true /* at_safepoint */); 1800 } 1801 // Resize and verify metaspace 1802 MetaspaceGC::compute_new_size(); 1803 DEBUG_ONLY(MetaspaceUtils::verify();) 1804 } 1805 1806 // Weak roots are either pre-evacuated (final mark) or updated (final updaterefs), 1807 // so they should not have forwarded oops. 1808 // However, we do need to "null" dead oops in the roots, if can not be done 1809 // in concurrent cycles. 1810 void ShenandoahHeap::stw_process_weak_roots(bool full_gc) { 1811 uint num_workers = _workers->active_workers(); 1812 ShenandoahPhaseTimings::Phase timing_phase = full_gc ? 1813 ShenandoahPhaseTimings::full_gc_purge_weak_par : 1814 ShenandoahPhaseTimings::degen_gc_purge_weak_par; 1815 ShenandoahGCPhase phase(timing_phase); 1816 ShenandoahGCWorkerPhase worker_phase(timing_phase); 1817 // Cleanup weak roots 1818 if (has_forwarded_objects()) { 1819 ShenandoahForwardedIsAliveClosure is_alive; 1820 ShenandoahUpdateRefsClosure keep_alive; 1821 ShenandoahParallelWeakRootsCleaningTask<ShenandoahForwardedIsAliveClosure, ShenandoahUpdateRefsClosure> 1822 cleaning_task(timing_phase, &is_alive, &keep_alive, num_workers); 1823 _workers->run_task(&cleaning_task); 1824 } else { 1825 ShenandoahIsAliveClosure is_alive; 1826 #ifdef ASSERT 1827 ShenandoahAssertNotForwardedClosure verify_cl; 1828 ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, ShenandoahAssertNotForwardedClosure> 1829 cleaning_task(timing_phase, &is_alive, &verify_cl, num_workers); 1830 #else 1831 ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, DoNothingClosure> 1832 cleaning_task(timing_phase, &is_alive, &do_nothing_cl, num_workers); 1833 #endif 1834 _workers->run_task(&cleaning_task); 1835 } 1836 } 1837 1838 void ShenandoahHeap::parallel_cleaning(bool full_gc) { 1839 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint"); 1840 assert(is_stw_gc_in_progress(), "Only for Degenerated and Full GC"); 1841 ShenandoahGCPhase phase(full_gc ? 1842 ShenandoahPhaseTimings::full_gc_purge : 1843 ShenandoahPhaseTimings::degen_gc_purge); 1844 stw_weak_refs(full_gc); 1845 stw_process_weak_roots(full_gc); 1846 stw_unload_classes(full_gc); 1847 } 1848 1849 void ShenandoahHeap::set_has_forwarded_objects(bool cond) { 1850 set_gc_state(HAS_FORWARDED, cond); 1851 } 1852 1853 void ShenandoahHeap::set_unload_classes(bool uc) { 1854 _unload_classes.set_cond(uc); 1855 } 1856 1857 bool ShenandoahHeap::unload_classes() const { 1858 return _unload_classes.is_set(); 1859 } 1860 1861 address ShenandoahHeap::in_cset_fast_test_addr() { 1862 ShenandoahHeap* heap = ShenandoahHeap::heap(); 1863 assert(heap->collection_set() != nullptr, "Sanity"); 1864 return (address) heap->collection_set()->biased_map_address(); 1865 } 1866 1867 size_t ShenandoahHeap::bytes_allocated_since_gc_start() { 1868 return Atomic::load(&_bytes_allocated_since_gc_start); 1869 } 1870 1871 void ShenandoahHeap::reset_bytes_allocated_since_gc_start() { 1872 Atomic::store(&_bytes_allocated_since_gc_start, (size_t)0); 1873 } 1874 1875 void ShenandoahHeap::set_degenerated_gc_in_progress(bool in_progress) { 1876 _degenerated_gc_in_progress.set_cond(in_progress); 1877 } 1878 1879 void ShenandoahHeap::set_full_gc_in_progress(bool in_progress) { 1880 _full_gc_in_progress.set_cond(in_progress); 1881 } 1882 1883 void ShenandoahHeap::set_full_gc_move_in_progress(bool in_progress) { 1884 assert (is_full_gc_in_progress(), "should be"); 1885 _full_gc_move_in_progress.set_cond(in_progress); 1886 } 1887 1888 void ShenandoahHeap::set_update_refs_in_progress(bool in_progress) { 1889 set_gc_state(UPDATEREFS, in_progress); 1890 } 1891 1892 void ShenandoahHeap::register_nmethod(nmethod* nm) { 1893 ShenandoahCodeRoots::register_nmethod(nm); 1894 } 1895 1896 void ShenandoahHeap::unregister_nmethod(nmethod* nm) { 1897 ShenandoahCodeRoots::unregister_nmethod(nm); 1898 } 1899 1900 void ShenandoahHeap::pin_object(JavaThread* thr, oop o) { 1901 heap_region_containing(o)->record_pin(); 1902 } 1903 1904 void ShenandoahHeap::unpin_object(JavaThread* thr, oop o) { 1905 ShenandoahHeapRegion* r = heap_region_containing(o); 1906 assert(r != nullptr, "Sanity"); 1907 assert(r->pin_count() > 0, "Region " SIZE_FORMAT " should have non-zero pins", r->index()); 1908 r->record_unpin(); 1909 } 1910 1911 void ShenandoahHeap::sync_pinned_region_status() { 1912 ShenandoahHeapLocker locker(lock()); 1913 1914 for (size_t i = 0; i < num_regions(); i++) { 1915 ShenandoahHeapRegion *r = get_region(i); 1916 if (r->is_active()) { 1917 if (r->is_pinned()) { 1918 if (r->pin_count() == 0) { 1919 r->make_unpinned(); 1920 } 1921 } else { 1922 if (r->pin_count() > 0) { 1923 r->make_pinned(); 1924 } 1925 } 1926 } 1927 } 1928 1929 assert_pinned_region_status(); 1930 } 1931 1932 #ifdef ASSERT 1933 void ShenandoahHeap::assert_pinned_region_status() { 1934 for (size_t i = 0; i < num_regions(); i++) { 1935 ShenandoahHeapRegion* r = get_region(i); 1936 assert((r->is_pinned() && r->pin_count() > 0) || (!r->is_pinned() && r->pin_count() == 0), 1937 "Region " SIZE_FORMAT " pinning status is inconsistent", i); 1938 } 1939 } 1940 #endif 1941 1942 ConcurrentGCTimer* ShenandoahHeap::gc_timer() const { 1943 return _gc_timer; 1944 } 1945 1946 void ShenandoahHeap::prepare_concurrent_roots() { 1947 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint"); 1948 assert(!is_stw_gc_in_progress(), "Only concurrent GC"); 1949 set_concurrent_strong_root_in_progress(!collection_set()->is_empty()); 1950 set_concurrent_weak_root_in_progress(true); 1951 if (unload_classes()) { 1952 _unloader.prepare(); 1953 } 1954 } 1955 1956 void ShenandoahHeap::finish_concurrent_roots() { 1957 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint"); 1958 assert(!is_stw_gc_in_progress(), "Only concurrent GC"); 1959 if (unload_classes()) { 1960 _unloader.finish(); 1961 } 1962 } 1963 1964 #ifdef ASSERT 1965 void ShenandoahHeap::assert_gc_workers(uint nworkers) { 1966 assert(nworkers > 0 && nworkers <= max_workers(), "Sanity"); 1967 1968 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) { 1969 if (UseDynamicNumberOfGCThreads) { 1970 assert(nworkers <= ParallelGCThreads, "Cannot use more than it has"); 1971 } else { 1972 // Use ParallelGCThreads inside safepoints 1973 assert(nworkers == ParallelGCThreads, "Use ParallelGCThreads within safepoints"); 1974 } 1975 } else { 1976 if (UseDynamicNumberOfGCThreads) { 1977 assert(nworkers <= ConcGCThreads, "Cannot use more than it has"); 1978 } else { 1979 // Use ConcGCThreads outside safepoints 1980 assert(nworkers == ConcGCThreads, "Use ConcGCThreads outside safepoints"); 1981 } 1982 } 1983 } 1984 #endif 1985 1986 ShenandoahVerifier* ShenandoahHeap::verifier() { 1987 guarantee(ShenandoahVerify, "Should be enabled"); 1988 assert (_verifier != nullptr, "sanity"); 1989 return _verifier; 1990 } 1991 1992 template<bool CONCURRENT> 1993 class ShenandoahUpdateHeapRefsTask : public WorkerTask { 1994 private: 1995 ShenandoahHeap* _heap; 1996 ShenandoahRegionIterator* _regions; 1997 public: 1998 ShenandoahUpdateHeapRefsTask(ShenandoahRegionIterator* regions) : 1999 WorkerTask("Shenandoah Update References"), 2000 _heap(ShenandoahHeap::heap()), 2001 _regions(regions) { 2002 } 2003 2004 void work(uint worker_id) { 2005 if (CONCURRENT) { 2006 ShenandoahConcurrentWorkerSession worker_session(worker_id); 2007 ShenandoahSuspendibleThreadSetJoiner stsj; 2008 do_work<ShenandoahConcUpdateRefsClosure>(); 2009 } else { 2010 ShenandoahParallelWorkerSession worker_session(worker_id); 2011 do_work<ShenandoahSTWUpdateRefsClosure>(); 2012 } 2013 } 2014 2015 private: 2016 template<class T> 2017 void do_work() { 2018 T cl; 2019 ShenandoahHeapRegion* r = _regions->next(); 2020 ShenandoahMarkingContext* const ctx = _heap->complete_marking_context(); 2021 while (r != nullptr) { 2022 HeapWord* update_watermark = r->get_update_watermark(); 2023 assert (update_watermark >= r->bottom(), "sanity"); 2024 if (r->is_active() && !r->is_cset()) { 2025 _heap->marked_object_oop_iterate(r, &cl, update_watermark); 2026 } 2027 if (ShenandoahPacing) { 2028 _heap->pacer()->report_updaterefs(pointer_delta(update_watermark, r->bottom())); 2029 } 2030 if (_heap->check_cancelled_gc_and_yield(CONCURRENT)) { 2031 return; 2032 } 2033 r = _regions->next(); 2034 } 2035 } 2036 }; 2037 2038 void ShenandoahHeap::update_heap_references(bool concurrent) { 2039 assert(!is_full_gc_in_progress(), "Only for concurrent and degenerated GC"); 2040 2041 if (concurrent) { 2042 ShenandoahUpdateHeapRefsTask<true> task(&_update_refs_iterator); 2043 workers()->run_task(&task); 2044 } else { 2045 ShenandoahUpdateHeapRefsTask<false> task(&_update_refs_iterator); 2046 workers()->run_task(&task); 2047 } 2048 } 2049 2050 2051 class ShenandoahFinalUpdateRefsUpdateRegionStateClosure : public ShenandoahHeapRegionClosure { 2052 private: 2053 ShenandoahHeapLock* const _lock; 2054 2055 public: 2056 ShenandoahFinalUpdateRefsUpdateRegionStateClosure() : _lock(ShenandoahHeap::heap()->lock()) {} 2057 2058 void heap_region_do(ShenandoahHeapRegion* r) { 2059 // Drop unnecessary "pinned" state from regions that does not have CP marks 2060 // anymore, as this would allow trashing them. 2061 2062 if (r->is_active()) { 2063 if (r->is_pinned()) { 2064 if (r->pin_count() == 0) { 2065 ShenandoahHeapLocker locker(_lock); 2066 r->make_unpinned(); 2067 } 2068 } else { 2069 if (r->pin_count() > 0) { 2070 ShenandoahHeapLocker locker(_lock); 2071 r->make_pinned(); 2072 } 2073 } 2074 } 2075 } 2076 2077 bool is_thread_safe() { return true; } 2078 }; 2079 2080 void ShenandoahHeap::update_heap_region_states(bool concurrent) { 2081 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint"); 2082 assert(!is_full_gc_in_progress(), "Only for concurrent and degenerated GC"); 2083 2084 { 2085 ShenandoahGCPhase phase(concurrent ? 2086 ShenandoahPhaseTimings::final_update_refs_update_region_states : 2087 ShenandoahPhaseTimings::degen_gc_final_update_refs_update_region_states); 2088 ShenandoahFinalUpdateRefsUpdateRegionStateClosure cl; 2089 parallel_heap_region_iterate(&cl); 2090 2091 assert_pinned_region_status(); 2092 } 2093 2094 { 2095 ShenandoahGCPhase phase(concurrent ? 2096 ShenandoahPhaseTimings::final_update_refs_trash_cset : 2097 ShenandoahPhaseTimings::degen_gc_final_update_refs_trash_cset); 2098 trash_cset_regions(); 2099 } 2100 } 2101 2102 void ShenandoahHeap::rebuild_free_set(bool concurrent) { 2103 { 2104 ShenandoahGCPhase phase(concurrent ? 2105 ShenandoahPhaseTimings::final_update_refs_rebuild_freeset : 2106 ShenandoahPhaseTimings::degen_gc_final_update_refs_rebuild_freeset); 2107 ShenandoahHeapLocker locker(lock()); 2108 _free_set->rebuild(); 2109 } 2110 } 2111 2112 void ShenandoahHeap::print_extended_on(outputStream *st) const { 2113 print_on(st); 2114 st->cr(); 2115 print_heap_regions_on(st); 2116 } 2117 2118 bool ShenandoahHeap::is_bitmap_slice_committed(ShenandoahHeapRegion* r, bool skip_self) { 2119 size_t slice = r->index() / _bitmap_regions_per_slice; 2120 2121 size_t regions_from = _bitmap_regions_per_slice * slice; 2122 size_t regions_to = MIN2(num_regions(), _bitmap_regions_per_slice * (slice + 1)); 2123 for (size_t g = regions_from; g < regions_to; g++) { 2124 assert (g / _bitmap_regions_per_slice == slice, "same slice"); 2125 if (skip_self && g == r->index()) continue; 2126 if (get_region(g)->is_committed()) { 2127 return true; 2128 } 2129 } 2130 return false; 2131 } 2132 2133 bool ShenandoahHeap::commit_bitmap_slice(ShenandoahHeapRegion* r) { 2134 shenandoah_assert_heaplocked(); 2135 2136 // Bitmaps in special regions do not need commits 2137 if (_bitmap_region_special) { 2138 return true; 2139 } 2140 2141 if (is_bitmap_slice_committed(r, true)) { 2142 // Some other region from the group is already committed, meaning the bitmap 2143 // slice is already committed, we exit right away. 2144 return true; 2145 } 2146 2147 // Commit the bitmap slice: 2148 size_t slice = r->index() / _bitmap_regions_per_slice; 2149 size_t off = _bitmap_bytes_per_slice * slice; 2150 size_t len = _bitmap_bytes_per_slice; 2151 char* start = (char*) _bitmap_region.start() + off; 2152 2153 if (!os::commit_memory(start, len, false)) { 2154 return false; 2155 } 2156 2157 if (AlwaysPreTouch) { 2158 os::pretouch_memory(start, start + len, _pretouch_bitmap_page_size); 2159 } 2160 2161 return true; 2162 } 2163 2164 bool ShenandoahHeap::uncommit_bitmap_slice(ShenandoahHeapRegion *r) { 2165 shenandoah_assert_heaplocked(); 2166 2167 // Bitmaps in special regions do not need uncommits 2168 if (_bitmap_region_special) { 2169 return true; 2170 } 2171 2172 if (is_bitmap_slice_committed(r, true)) { 2173 // Some other region from the group is still committed, meaning the bitmap 2174 // slice is should stay committed, exit right away. 2175 return true; 2176 } 2177 2178 // Uncommit the bitmap slice: 2179 size_t slice = r->index() / _bitmap_regions_per_slice; 2180 size_t off = _bitmap_bytes_per_slice * slice; 2181 size_t len = _bitmap_bytes_per_slice; 2182 if (!os::uncommit_memory((char*)_bitmap_region.start() + off, len)) { 2183 return false; 2184 } 2185 return true; 2186 } 2187 2188 void ShenandoahHeap::safepoint_synchronize_begin() { 2189 SuspendibleThreadSet::synchronize(); 2190 } 2191 2192 void ShenandoahHeap::safepoint_synchronize_end() { 2193 SuspendibleThreadSet::desynchronize(); 2194 } 2195 2196 void ShenandoahHeap::entry_uncommit(double shrink_before, size_t shrink_until) { 2197 static const char *msg = "Concurrent uncommit"; 2198 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_uncommit, true /* log_heap_usage */); 2199 EventMark em("%s", msg); 2200 2201 op_uncommit(shrink_before, shrink_until); 2202 } 2203 2204 void ShenandoahHeap::try_inject_alloc_failure() { 2205 if (ShenandoahAllocFailureALot && !cancelled_gc() && ((os::random() % 1000) > 950)) { 2206 _inject_alloc_failure.set(); 2207 os::naked_short_sleep(1); 2208 if (cancelled_gc()) { 2209 log_info(gc)("Allocation failure was successfully injected"); 2210 } 2211 } 2212 } 2213 2214 bool ShenandoahHeap::should_inject_alloc_failure() { 2215 return _inject_alloc_failure.is_set() && _inject_alloc_failure.try_unset(); 2216 } 2217 2218 void ShenandoahHeap::initialize_serviceability() { 2219 _memory_pool = new ShenandoahMemoryPool(this); 2220 _cycle_memory_manager.add_pool(_memory_pool); 2221 _stw_memory_manager.add_pool(_memory_pool); 2222 } 2223 2224 GrowableArray<GCMemoryManager*> ShenandoahHeap::memory_managers() { 2225 GrowableArray<GCMemoryManager*> memory_managers(2); 2226 memory_managers.append(&_cycle_memory_manager); 2227 memory_managers.append(&_stw_memory_manager); 2228 return memory_managers; 2229 } 2230 2231 GrowableArray<MemoryPool*> ShenandoahHeap::memory_pools() { 2232 GrowableArray<MemoryPool*> memory_pools(1); 2233 memory_pools.append(_memory_pool); 2234 return memory_pools; 2235 } 2236 2237 MemoryUsage ShenandoahHeap::memory_usage() { 2238 return _memory_pool->get_memory_usage(); 2239 } 2240 2241 ShenandoahRegionIterator::ShenandoahRegionIterator() : 2242 _heap(ShenandoahHeap::heap()), 2243 _index(0) {} 2244 2245 ShenandoahRegionIterator::ShenandoahRegionIterator(ShenandoahHeap* heap) : 2246 _heap(heap), 2247 _index(0) {} 2248 2249 void ShenandoahRegionIterator::reset() { 2250 _index = 0; 2251 } 2252 2253 bool ShenandoahRegionIterator::has_next() const { 2254 return _index < _heap->num_regions(); 2255 } 2256 2257 char ShenandoahHeap::gc_state() const { 2258 return _gc_state.raw_value(); 2259 } 2260 2261 ShenandoahLiveData* ShenandoahHeap::get_liveness_cache(uint worker_id) { 2262 #ifdef ASSERT 2263 assert(_liveness_cache != nullptr, "sanity"); 2264 assert(worker_id < _max_workers, "sanity"); 2265 for (uint i = 0; i < num_regions(); i++) { 2266 assert(_liveness_cache[worker_id][i] == 0, "liveness cache should be empty"); 2267 } 2268 #endif 2269 return _liveness_cache[worker_id]; 2270 } 2271 2272 void ShenandoahHeap::flush_liveness_cache(uint worker_id) { 2273 assert(worker_id < _max_workers, "sanity"); 2274 assert(_liveness_cache != nullptr, "sanity"); 2275 ShenandoahLiveData* ld = _liveness_cache[worker_id]; 2276 for (uint i = 0; i < num_regions(); i++) { 2277 ShenandoahLiveData live = ld[i]; 2278 if (live > 0) { 2279 ShenandoahHeapRegion* r = get_region(i); 2280 r->increase_live_data_gc_words(live); 2281 ld[i] = 0; 2282 } 2283 } 2284 } 2285 2286 bool ShenandoahHeap::requires_barriers(stackChunkOop obj) const { 2287 if (is_idle()) return false; 2288 2289 // Objects allocated after marking start are implicitly alive, don't need any barriers during 2290 // marking phase. 2291 if (is_concurrent_mark_in_progress() && 2292 !marking_context()->allocated_after_mark_start(obj)) { 2293 return true; 2294 } 2295 2296 // Can not guarantee obj is deeply good. 2297 if (has_forwarded_objects()) { 2298 return true; 2299 } 2300 2301 return false; 2302 }