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/gcArguments.hpp" 31 #include "gc/shared/gcTimer.hpp" 32 #include "gc/shared/gcTraceTime.inline.hpp" 33 #include "gc/shared/locationPrinter.inline.hpp" 34 #include "gc/shared/memAllocator.hpp" 35 #include "gc/shared/plab.hpp" 36 #include "gc/shared/tlab_globals.hpp" 37 38 #include "gc/shenandoah/shenandoahBarrierSet.hpp" 39 #include "gc/shenandoah/shenandoahClosures.inline.hpp" 40 #include "gc/shenandoah/shenandoahCollectionSet.hpp" 41 #include "gc/shenandoah/shenandoahCollectorPolicy.hpp" 42 #include "gc/shenandoah/shenandoahConcurrentMark.hpp" 43 #include "gc/shenandoah/shenandoahMarkingContext.inline.hpp" 44 #include "gc/shenandoah/shenandoahControlThread.hpp" 45 #include "gc/shenandoah/shenandoahFreeSet.hpp" 46 #include "gc/shenandoah/shenandoahPhaseTimings.hpp" 47 #include "gc/shenandoah/shenandoahHeap.inline.hpp" 48 #include "gc/shenandoah/shenandoahHeapRegion.inline.hpp" 49 #include "gc/shenandoah/shenandoahHeapRegionSet.hpp" 50 #include "gc/shenandoah/shenandoahInitLogger.hpp" 51 #include "gc/shenandoah/shenandoahMarkingContext.inline.hpp" 52 #include "gc/shenandoah/shenandoahMemoryPool.hpp" 53 #include "gc/shenandoah/shenandoahMetrics.hpp" 54 #include "gc/shenandoah/shenandoahMonitoringSupport.hpp" 55 #include "gc/shenandoah/shenandoahOopClosures.inline.hpp" 56 #include "gc/shenandoah/shenandoahPacer.inline.hpp" 57 #include "gc/shenandoah/shenandoahPadding.hpp" 58 #include "gc/shenandoah/shenandoahParallelCleaning.inline.hpp" 59 #include "gc/shenandoah/shenandoahReferenceProcessor.hpp" 60 #include "gc/shenandoah/shenandoahRootProcessor.inline.hpp" 61 #include "gc/shenandoah/shenandoahSTWMark.hpp" 62 #include "gc/shenandoah/shenandoahUtils.hpp" 63 #include "gc/shenandoah/shenandoahVerifier.hpp" 64 #include "gc/shenandoah/shenandoahCodeRoots.hpp" 65 #include "gc/shenandoah/shenandoahVMOperations.hpp" 66 #include "gc/shenandoah/shenandoahWorkGroup.hpp" 67 #include "gc/shenandoah/shenandoahWorkerPolicy.hpp" 68 #include "gc/shenandoah/mode/shenandoahIUMode.hpp" 69 #include "gc/shenandoah/mode/shenandoahPassiveMode.hpp" 70 #include "gc/shenandoah/mode/shenandoahSATBMode.hpp" 71 #if INCLUDE_JFR 72 #include "gc/shenandoah/shenandoahJfrSupport.hpp" 73 #endif 74 75 #include "classfile/systemDictionary.hpp" 76 #include "code/codeCache.hpp" 77 #include "memory/classLoaderMetaspace.hpp" 78 #include "memory/metaspaceUtils.hpp" 79 #include "oops/compressedOops.inline.hpp" 80 #include "prims/jvmtiTagMap.hpp" 81 #include "runtime/atomic.hpp" 82 #include "runtime/globals.hpp" 83 #include "runtime/interfaceSupport.inline.hpp" 84 #include "runtime/java.hpp" 85 #include "runtime/orderAccess.hpp" 86 #include "runtime/safepointMechanism.hpp" 87 #include "runtime/vmThread.hpp" 88 #include "services/mallocTracker.hpp" 89 #include "services/memTracker.hpp" 90 #include "utilities/events.hpp" 91 #include "utilities/powerOfTwo.hpp" 92 93 class ShenandoahPretouchHeapTask : public WorkerTask { 94 private: 95 ShenandoahRegionIterator _regions; 96 const size_t _page_size; 97 public: 98 ShenandoahPretouchHeapTask(size_t page_size) : 99 WorkerTask("Shenandoah Pretouch Heap"), 100 _page_size(page_size) {} 101 102 virtual void work(uint worker_id) { 103 ShenandoahHeapRegion* r = _regions.next(); 104 while (r != nullptr) { 105 if (r->is_committed()) { 106 os::pretouch_memory(r->bottom(), r->end(), _page_size); 107 } 108 r = _regions.next(); 109 } 110 } 111 }; 112 113 class ShenandoahPretouchBitmapTask : public WorkerTask { 114 private: 115 ShenandoahRegionIterator _regions; 116 char* _bitmap_base; 117 const size_t _bitmap_size; 118 const size_t _page_size; 119 public: 120 ShenandoahPretouchBitmapTask(char* bitmap_base, size_t bitmap_size, size_t page_size) : 121 WorkerTask("Shenandoah Pretouch Bitmap"), 122 _bitmap_base(bitmap_base), 123 _bitmap_size(bitmap_size), 124 _page_size(page_size) {} 125 126 virtual void work(uint worker_id) { 127 ShenandoahHeapRegion* r = _regions.next(); 128 while (r != nullptr) { 129 size_t start = r->index() * ShenandoahHeapRegion::region_size_bytes() / MarkBitMap::heap_map_factor(); 130 size_t end = (r->index() + 1) * ShenandoahHeapRegion::region_size_bytes() / MarkBitMap::heap_map_factor(); 131 assert (end <= _bitmap_size, "end is sane: " SIZE_FORMAT " < " SIZE_FORMAT, end, _bitmap_size); 132 133 if (r->is_committed()) { 134 os::pretouch_memory(_bitmap_base + start, _bitmap_base + end, _page_size); 135 } 136 137 r = _regions.next(); 138 } 139 } 140 }; 141 142 jint ShenandoahHeap::initialize() { 143 // 144 // Figure out heap sizing 145 // 146 147 size_t init_byte_size = InitialHeapSize; 148 size_t min_byte_size = MinHeapSize; 149 size_t max_byte_size = MaxHeapSize; 150 size_t heap_alignment = HeapAlignment; 151 152 size_t reg_size_bytes = ShenandoahHeapRegion::region_size_bytes(); 153 154 Universe::check_alignment(max_byte_size, reg_size_bytes, "Shenandoah heap"); 155 Universe::check_alignment(init_byte_size, reg_size_bytes, "Shenandoah heap"); 156 157 _num_regions = ShenandoahHeapRegion::region_count(); 158 assert(_num_regions == (max_byte_size / reg_size_bytes), 159 "Regions should cover entire heap exactly: " SIZE_FORMAT " != " SIZE_FORMAT "/" SIZE_FORMAT, 160 _num_regions, max_byte_size, reg_size_bytes); 161 162 // Now we know the number of regions, initialize the heuristics. 163 initialize_heuristics(); 164 165 size_t num_committed_regions = init_byte_size / reg_size_bytes; 166 num_committed_regions = MIN2(num_committed_regions, _num_regions); 167 assert(num_committed_regions <= _num_regions, "sanity"); 168 _initial_size = num_committed_regions * reg_size_bytes; 169 170 size_t num_min_regions = min_byte_size / reg_size_bytes; 171 num_min_regions = MIN2(num_min_regions, _num_regions); 172 assert(num_min_regions <= _num_regions, "sanity"); 173 _minimum_size = num_min_regions * reg_size_bytes; 174 175 // Default to max heap size. 176 _soft_max_size = _num_regions * reg_size_bytes; 177 178 _committed = _initial_size; 179 180 size_t heap_page_size = UseLargePages ? os::large_page_size() : os::vm_page_size(); 181 size_t bitmap_page_size = UseLargePages ? os::large_page_size() : os::vm_page_size(); 182 size_t region_page_size = UseLargePages ? os::large_page_size() : os::vm_page_size(); 183 184 // 185 // Reserve and commit memory for heap 186 // 187 188 ReservedHeapSpace heap_rs = Universe::reserve_heap(max_byte_size, heap_alignment); 189 initialize_reserved_region(heap_rs); 190 _heap_region = MemRegion((HeapWord*)heap_rs.base(), heap_rs.size() / HeapWordSize); 191 _heap_region_special = heap_rs.special(); 192 193 assert((((size_t) base()) & ShenandoahHeapRegion::region_size_bytes_mask()) == 0, 194 "Misaligned heap: " PTR_FORMAT, p2i(base())); 195 196 #if SHENANDOAH_OPTIMIZED_MARKTASK 197 // The optimized ShenandoahMarkTask takes some bits away from the full object bits. 198 // Fail if we ever attempt to address more than we can. 199 if ((uintptr_t)heap_rs.end() >= ShenandoahMarkTask::max_addressable()) { 200 FormatBuffer<512> buf("Shenandoah reserved [" PTR_FORMAT ", " PTR_FORMAT") for the heap, \n" 201 "but max object address is " PTR_FORMAT ". Try to reduce heap size, or try other \n" 202 "VM options that allocate heap at lower addresses (HeapBaseMinAddress, AllocateHeapAt, etc).", 203 p2i(heap_rs.base()), p2i(heap_rs.end()), ShenandoahMarkTask::max_addressable()); 204 vm_exit_during_initialization("Fatal Error", buf); 205 } 206 #endif 207 208 ReservedSpace sh_rs = heap_rs.first_part(max_byte_size); 209 if (!_heap_region_special) { 210 os::commit_memory_or_exit(sh_rs.base(), _initial_size, heap_alignment, false, 211 "Cannot commit heap memory"); 212 } 213 214 // 215 // Reserve and commit memory for bitmap(s) 216 // 217 218 _bitmap_size = ShenandoahMarkBitMap::compute_size(heap_rs.size()); 219 _bitmap_size = align_up(_bitmap_size, bitmap_page_size); 220 221 size_t bitmap_bytes_per_region = reg_size_bytes / ShenandoahMarkBitMap::heap_map_factor(); 222 223 guarantee(bitmap_bytes_per_region != 0, 224 "Bitmap bytes per region should not be zero"); 225 guarantee(is_power_of_2(bitmap_bytes_per_region), 226 "Bitmap bytes per region should be power of two: " SIZE_FORMAT, bitmap_bytes_per_region); 227 228 if (bitmap_page_size > bitmap_bytes_per_region) { 229 _bitmap_regions_per_slice = bitmap_page_size / bitmap_bytes_per_region; 230 _bitmap_bytes_per_slice = bitmap_page_size; 231 } else { 232 _bitmap_regions_per_slice = 1; 233 _bitmap_bytes_per_slice = bitmap_bytes_per_region; 234 } 235 236 guarantee(_bitmap_regions_per_slice >= 1, 237 "Should have at least one region per slice: " SIZE_FORMAT, 238 _bitmap_regions_per_slice); 239 240 guarantee(((_bitmap_bytes_per_slice) % bitmap_page_size) == 0, 241 "Bitmap slices should be page-granular: bps = " SIZE_FORMAT ", page size = " SIZE_FORMAT, 242 _bitmap_bytes_per_slice, bitmap_page_size); 243 244 ReservedSpace bitmap(_bitmap_size, bitmap_page_size); 245 MemTracker::record_virtual_memory_type(bitmap.base(), mtGC); 246 _bitmap_region = MemRegion((HeapWord*) bitmap.base(), bitmap.size() / HeapWordSize); 247 _bitmap_region_special = bitmap.special(); 248 249 size_t bitmap_init_commit = _bitmap_bytes_per_slice * 250 align_up(num_committed_regions, _bitmap_regions_per_slice) / _bitmap_regions_per_slice; 251 bitmap_init_commit = MIN2(_bitmap_size, bitmap_init_commit); 252 if (!_bitmap_region_special) { 253 os::commit_memory_or_exit((char *) _bitmap_region.start(), bitmap_init_commit, bitmap_page_size, false, 254 "Cannot commit bitmap memory"); 255 } 256 257 _marking_context = new ShenandoahMarkingContext(_heap_region, _bitmap_region, _num_regions, _max_workers); 258 259 if (ShenandoahVerify) { 260 ReservedSpace verify_bitmap(_bitmap_size, bitmap_page_size); 261 if (!verify_bitmap.special()) { 262 os::commit_memory_or_exit(verify_bitmap.base(), verify_bitmap.size(), bitmap_page_size, false, 263 "Cannot commit verification bitmap memory"); 264 } 265 MemTracker::record_virtual_memory_type(verify_bitmap.base(), mtGC); 266 MemRegion verify_bitmap_region = MemRegion((HeapWord *) verify_bitmap.base(), verify_bitmap.size() / HeapWordSize); 267 _verification_bit_map.initialize(_heap_region, verify_bitmap_region); 268 _verifier = new ShenandoahVerifier(this, &_verification_bit_map); 269 } 270 271 // Reserve aux bitmap for use in object_iterate(). We don't commit it here. 272 ReservedSpace aux_bitmap(_bitmap_size, bitmap_page_size); 273 MemTracker::record_virtual_memory_type(aux_bitmap.base(), mtGC); 274 _aux_bitmap_region = MemRegion((HeapWord*) aux_bitmap.base(), aux_bitmap.size() / HeapWordSize); 275 _aux_bitmap_region_special = aux_bitmap.special(); 276 _aux_bit_map.initialize(_heap_region, _aux_bitmap_region); 277 278 // 279 // Create regions and region sets 280 // 281 size_t region_align = align_up(sizeof(ShenandoahHeapRegion), SHENANDOAH_CACHE_LINE_SIZE); 282 size_t region_storage_size = align_up(region_align * _num_regions, region_page_size); 283 region_storage_size = align_up(region_storage_size, os::vm_allocation_granularity()); 284 285 ReservedSpace region_storage(region_storage_size, region_page_size); 286 MemTracker::record_virtual_memory_type(region_storage.base(), mtGC); 287 if (!region_storage.special()) { 288 os::commit_memory_or_exit(region_storage.base(), region_storage_size, region_page_size, false, 289 "Cannot commit region memory"); 290 } 291 292 // Try to fit the collection set bitmap at lower addresses. This optimizes code generation for cset checks. 293 // Go up until a sensible limit (subject to encoding constraints) and try to reserve the space there. 294 // If not successful, bite a bullet and allocate at whatever address. 295 { 296 size_t cset_align = MAX2<size_t>(os::vm_page_size(), os::vm_allocation_granularity()); 297 size_t cset_size = align_up(((size_t) sh_rs.base() + sh_rs.size()) >> ShenandoahHeapRegion::region_size_bytes_shift(), cset_align); 298 299 uintptr_t min = round_up_power_of_2(cset_align); 300 uintptr_t max = (1u << 30u); 301 302 for (uintptr_t addr = min; addr <= max; addr <<= 1u) { 303 char* req_addr = (char*)addr; 304 assert(is_aligned(req_addr, cset_align), "Should be aligned"); 305 ReservedSpace cset_rs(cset_size, cset_align, os::vm_page_size(), req_addr); 306 if (cset_rs.is_reserved()) { 307 assert(cset_rs.base() == req_addr, "Allocated where requested: " PTR_FORMAT ", " PTR_FORMAT, p2i(cset_rs.base()), addr); 308 _collection_set = new ShenandoahCollectionSet(this, cset_rs, sh_rs.base()); 309 break; 310 } 311 } 312 313 if (_collection_set == nullptr) { 314 ReservedSpace cset_rs(cset_size, cset_align, os::vm_page_size()); 315 _collection_set = new ShenandoahCollectionSet(this, cset_rs, sh_rs.base()); 316 } 317 } 318 319 _regions = NEW_C_HEAP_ARRAY(ShenandoahHeapRegion*, _num_regions, mtGC); 320 _free_set = new ShenandoahFreeSet(this, _num_regions); 321 322 { 323 ShenandoahHeapLocker locker(lock()); 324 325 for (size_t i = 0; i < _num_regions; i++) { 326 HeapWord* start = (HeapWord*)sh_rs.base() + ShenandoahHeapRegion::region_size_words() * i; 327 bool is_committed = i < num_committed_regions; 328 void* loc = region_storage.base() + i * region_align; 329 330 ShenandoahHeapRegion* r = new (loc) ShenandoahHeapRegion(start, i, is_committed); 331 assert(is_aligned(r, SHENANDOAH_CACHE_LINE_SIZE), "Sanity"); 332 333 _marking_context->initialize_top_at_mark_start(r); 334 _regions[i] = r; 335 assert(!collection_set()->is_in(i), "New region should not be in collection set"); 336 } 337 338 // Initialize to complete 339 _marking_context->mark_complete(); 340 341 _free_set->rebuild(); 342 } 343 344 if (AlwaysPreTouch) { 345 // For NUMA, it is important to pre-touch the storage under bitmaps with worker threads, 346 // before initialize() below zeroes it with initializing thread. For any given region, 347 // we touch the region and the corresponding bitmaps from the same thread. 348 ShenandoahPushWorkerScope scope(workers(), _max_workers, false); 349 350 _pretouch_heap_page_size = heap_page_size; 351 _pretouch_bitmap_page_size = bitmap_page_size; 352 353 #ifdef LINUX 354 // UseTransparentHugePages would madvise that backing memory can be coalesced into huge 355 // pages. But, the kernel needs to know that every small page is used, in order to coalesce 356 // them into huge one. Therefore, we need to pretouch with smaller pages. 357 if (UseTransparentHugePages) { 358 _pretouch_heap_page_size = (size_t)os::vm_page_size(); 359 _pretouch_bitmap_page_size = (size_t)os::vm_page_size(); 360 } 361 #endif 362 363 // OS memory managers may want to coalesce back-to-back pages. Make their jobs 364 // simpler by pre-touching continuous spaces (heap and bitmap) separately. 365 366 ShenandoahPretouchBitmapTask bcl(bitmap.base(), _bitmap_size, _pretouch_bitmap_page_size); 367 _workers->run_task(&bcl); 368 369 ShenandoahPretouchHeapTask hcl(_pretouch_heap_page_size); 370 _workers->run_task(&hcl); 371 } 372 373 // 374 // Initialize the rest of GC subsystems 375 // 376 377 _liveness_cache = NEW_C_HEAP_ARRAY(ShenandoahLiveData*, _max_workers, mtGC); 378 for (uint worker = 0; worker < _max_workers; worker++) { 379 _liveness_cache[worker] = NEW_C_HEAP_ARRAY(ShenandoahLiveData, _num_regions, mtGC); 380 Copy::fill_to_bytes(_liveness_cache[worker], _num_regions * sizeof(ShenandoahLiveData)); 381 } 382 383 // There should probably be Shenandoah-specific options for these, 384 // just as there are G1-specific options. 385 { 386 ShenandoahSATBMarkQueueSet& satbqs = ShenandoahBarrierSet::satb_mark_queue_set(); 387 satbqs.set_process_completed_buffers_threshold(20); // G1SATBProcessCompletedThreshold 388 satbqs.set_buffer_enqueue_threshold_percentage(60); // G1SATBBufferEnqueueingThresholdPercent 389 } 390 391 _monitoring_support = new ShenandoahMonitoringSupport(this); 392 _phase_timings = new ShenandoahPhaseTimings(max_workers()); 393 ShenandoahCodeRoots::initialize(); 394 395 if (ShenandoahPacing) { 396 _pacer = new ShenandoahPacer(this); 397 _pacer->setup_for_idle(); 398 } else { 399 _pacer = nullptr; 400 } 401 402 _control_thread = new ShenandoahControlThread(); 403 404 ShenandoahInitLogger::print(); 405 406 return JNI_OK; 407 } 408 409 void ShenandoahHeap::initialize_mode() { 410 if (ShenandoahGCMode != nullptr) { 411 if (strcmp(ShenandoahGCMode, "satb") == 0) { 412 _gc_mode = new ShenandoahSATBMode(); 413 } else if (strcmp(ShenandoahGCMode, "iu") == 0) { 414 _gc_mode = new ShenandoahIUMode(); 415 } else if (strcmp(ShenandoahGCMode, "passive") == 0) { 416 _gc_mode = new ShenandoahPassiveMode(); 417 } else { 418 vm_exit_during_initialization("Unknown -XX:ShenandoahGCMode option"); 419 } 420 } else { 421 vm_exit_during_initialization("Unknown -XX:ShenandoahGCMode option (null)"); 422 } 423 _gc_mode->initialize_flags(); 424 if (_gc_mode->is_diagnostic() && !UnlockDiagnosticVMOptions) { 425 vm_exit_during_initialization( 426 err_msg("GC mode \"%s\" is diagnostic, and must be enabled via -XX:+UnlockDiagnosticVMOptions.", 427 _gc_mode->name())); 428 } 429 if (_gc_mode->is_experimental() && !UnlockExperimentalVMOptions) { 430 vm_exit_during_initialization( 431 err_msg("GC mode \"%s\" is experimental, and must be enabled via -XX:+UnlockExperimentalVMOptions.", 432 _gc_mode->name())); 433 } 434 } 435 436 void ShenandoahHeap::initialize_heuristics() { 437 assert(_gc_mode != nullptr, "Must be initialized"); 438 _heuristics = _gc_mode->initialize_heuristics(); 439 440 if (_heuristics->is_diagnostic() && !UnlockDiagnosticVMOptions) { 441 vm_exit_during_initialization( 442 err_msg("Heuristics \"%s\" is diagnostic, and must be enabled via -XX:+UnlockDiagnosticVMOptions.", 443 _heuristics->name())); 444 } 445 if (_heuristics->is_experimental() && !UnlockExperimentalVMOptions) { 446 vm_exit_during_initialization( 447 err_msg("Heuristics \"%s\" is experimental, and must be enabled via -XX:+UnlockExperimentalVMOptions.", 448 _heuristics->name())); 449 } 450 } 451 452 #ifdef _MSC_VER 453 #pragma warning( push ) 454 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list 455 #endif 456 457 ShenandoahHeap::ShenandoahHeap(ShenandoahCollectorPolicy* policy) : 458 CollectedHeap(), 459 _initial_size(0), 460 _used(0), 461 _committed(0), 462 _bytes_allocated_since_gc_start(0), 463 _max_workers(MAX2(ConcGCThreads, ParallelGCThreads)), 464 _workers(nullptr), 465 _safepoint_workers(nullptr), 466 _heap_region_special(false), 467 _num_regions(0), 468 _regions(nullptr), 469 _update_refs_iterator(this), 470 _control_thread(nullptr), 471 _shenandoah_policy(policy), 472 _gc_mode(nullptr), 473 _heuristics(nullptr), 474 _free_set(nullptr), 475 _pacer(nullptr), 476 _verifier(nullptr), 477 _phase_timings(nullptr), 478 _monitoring_support(nullptr), 479 _memory_pool(nullptr), 480 _stw_memory_manager("Shenandoah Pauses"), 481 _cycle_memory_manager("Shenandoah Cycles"), 482 _gc_timer(new ConcurrentGCTimer()), 483 _soft_ref_policy(), 484 _log_min_obj_alignment_in_bytes(LogMinObjAlignmentInBytes), 485 _ref_processor(new ShenandoahReferenceProcessor(MAX2(_max_workers, 1U))), 486 _marking_context(nullptr), 487 _bitmap_size(0), 488 _bitmap_regions_per_slice(0), 489 _bitmap_bytes_per_slice(0), 490 _bitmap_region_special(false), 491 _aux_bitmap_region_special(false), 492 _liveness_cache(nullptr), 493 _collection_set(nullptr) 494 { 495 // Initialize GC mode early, so we can adjust barrier support 496 initialize_mode(); 497 BarrierSet::set_barrier_set(new ShenandoahBarrierSet(this)); 498 499 _max_workers = MAX2(_max_workers, 1U); 500 _workers = new ShenandoahWorkerThreads("Shenandoah GC Threads", _max_workers); 501 if (_workers == nullptr) { 502 vm_exit_during_initialization("Failed necessary allocation."); 503 } else { 504 _workers->initialize_workers(); 505 } 506 507 if (ParallelGCThreads > 1) { 508 _safepoint_workers = new ShenandoahWorkerThreads("Safepoint Cleanup Thread", 509 ParallelGCThreads); 510 _safepoint_workers->initialize_workers(); 511 } 512 } 513 514 #ifdef _MSC_VER 515 #pragma warning( pop ) 516 #endif 517 518 class ShenandoahResetBitmapTask : public WorkerTask { 519 private: 520 ShenandoahRegionIterator _regions; 521 522 public: 523 ShenandoahResetBitmapTask() : 524 WorkerTask("Shenandoah Reset Bitmap") {} 525 526 void work(uint worker_id) { 527 ShenandoahHeapRegion* region = _regions.next(); 528 ShenandoahHeap* heap = ShenandoahHeap::heap(); 529 ShenandoahMarkingContext* const ctx = heap->marking_context(); 530 while (region != nullptr) { 531 if (heap->is_bitmap_slice_committed(region)) { 532 ctx->clear_bitmap(region); 533 } 534 region = _regions.next(); 535 } 536 } 537 }; 538 539 void ShenandoahHeap::reset_mark_bitmap() { 540 assert_gc_workers(_workers->active_workers()); 541 mark_incomplete_marking_context(); 542 543 ShenandoahResetBitmapTask task; 544 _workers->run_task(&task); 545 } 546 547 void ShenandoahHeap::print_on(outputStream* st) const { 548 st->print_cr("Shenandoah Heap"); 549 st->print_cr(" " SIZE_FORMAT "%s max, " SIZE_FORMAT "%s soft max, " SIZE_FORMAT "%s committed, " SIZE_FORMAT "%s used", 550 byte_size_in_proper_unit(max_capacity()), proper_unit_for_byte_size(max_capacity()), 551 byte_size_in_proper_unit(soft_max_capacity()), proper_unit_for_byte_size(soft_max_capacity()), 552 byte_size_in_proper_unit(committed()), proper_unit_for_byte_size(committed()), 553 byte_size_in_proper_unit(used()), proper_unit_for_byte_size(used())); 554 st->print_cr(" " SIZE_FORMAT " x " SIZE_FORMAT"%s regions", 555 num_regions(), 556 byte_size_in_proper_unit(ShenandoahHeapRegion::region_size_bytes()), 557 proper_unit_for_byte_size(ShenandoahHeapRegion::region_size_bytes())); 558 559 st->print("Status: "); 560 if (has_forwarded_objects()) st->print("has forwarded objects, "); 561 if (is_concurrent_mark_in_progress()) st->print("marking, "); 562 if (is_evacuation_in_progress()) st->print("evacuating, "); 563 if (is_update_refs_in_progress()) st->print("updating refs, "); 564 if (is_degenerated_gc_in_progress()) st->print("degenerated gc, "); 565 if (is_full_gc_in_progress()) st->print("full gc, "); 566 if (is_full_gc_move_in_progress()) st->print("full gc move, "); 567 if (is_concurrent_weak_root_in_progress()) st->print("concurrent weak roots, "); 568 if (is_concurrent_strong_root_in_progress() && 569 !is_concurrent_weak_root_in_progress()) st->print("concurrent strong roots, "); 570 571 if (cancelled_gc()) { 572 st->print("cancelled"); 573 } else { 574 st->print("not cancelled"); 575 } 576 st->cr(); 577 578 st->print_cr("Reserved region:"); 579 st->print_cr(" - [" PTR_FORMAT ", " PTR_FORMAT ") ", 580 p2i(reserved_region().start()), 581 p2i(reserved_region().end())); 582 583 ShenandoahCollectionSet* cset = collection_set(); 584 st->print_cr("Collection set:"); 585 if (cset != nullptr) { 586 st->print_cr(" - map (vanilla): " PTR_FORMAT, p2i(cset->map_address())); 587 st->print_cr(" - map (biased): " PTR_FORMAT, p2i(cset->biased_map_address())); 588 } else { 589 st->print_cr(" (null)"); 590 } 591 592 st->cr(); 593 MetaspaceUtils::print_on(st); 594 595 if (Verbose) { 596 print_heap_regions_on(st); 597 } 598 } 599 600 class ShenandoahInitWorkerGCLABClosure : public ThreadClosure { 601 public: 602 void do_thread(Thread* thread) { 603 assert(thread != nullptr, "Sanity"); 604 assert(thread->is_Worker_thread(), "Only worker thread expected"); 605 ShenandoahThreadLocalData::initialize_gclab(thread); 606 } 607 }; 608 609 void ShenandoahHeap::post_initialize() { 610 CollectedHeap::post_initialize(); 611 MutexLocker ml(Threads_lock); 612 613 ShenandoahInitWorkerGCLABClosure init_gclabs; 614 _workers->threads_do(&init_gclabs); 615 616 // gclab can not be initialized early during VM startup, as it can not determinate its max_size. 617 // Now, we will let WorkerThreads to initialize gclab when new worker is created. 618 _workers->set_initialize_gclab(); 619 if (_safepoint_workers != nullptr) { 620 _safepoint_workers->threads_do(&init_gclabs); 621 _safepoint_workers->set_initialize_gclab(); 622 } 623 624 _heuristics->initialize(); 625 626 JFR_ONLY(ShenandoahJFRSupport::register_jfr_type_serializers()); 627 } 628 629 size_t ShenandoahHeap::used() const { 630 return Atomic::load(&_used); 631 } 632 633 size_t ShenandoahHeap::committed() const { 634 return Atomic::load(&_committed); 635 } 636 637 void ShenandoahHeap::increase_committed(size_t bytes) { 638 shenandoah_assert_heaplocked_or_safepoint(); 639 _committed += bytes; 640 } 641 642 void ShenandoahHeap::decrease_committed(size_t bytes) { 643 shenandoah_assert_heaplocked_or_safepoint(); 644 _committed -= bytes; 645 } 646 647 void ShenandoahHeap::increase_used(size_t bytes) { 648 Atomic::add(&_used, bytes, memory_order_relaxed); 649 } 650 651 void ShenandoahHeap::set_used(size_t bytes) { 652 Atomic::store(&_used, bytes); 653 } 654 655 void ShenandoahHeap::decrease_used(size_t bytes) { 656 assert(used() >= bytes, "never decrease heap size by more than we've left"); 657 Atomic::sub(&_used, bytes, memory_order_relaxed); 658 } 659 660 void ShenandoahHeap::increase_allocated(size_t bytes) { 661 Atomic::add(&_bytes_allocated_since_gc_start, bytes, memory_order_relaxed); 662 } 663 664 void ShenandoahHeap::notify_mutator_alloc_words(size_t words, bool waste) { 665 size_t bytes = words * HeapWordSize; 666 if (!waste) { 667 increase_used(bytes); 668 } 669 increase_allocated(bytes); 670 if (ShenandoahPacing) { 671 control_thread()->pacing_notify_alloc(words); 672 if (waste) { 673 pacer()->claim_for_alloc(words, true); 674 } 675 } 676 } 677 678 size_t ShenandoahHeap::capacity() const { 679 return committed(); 680 } 681 682 size_t ShenandoahHeap::max_capacity() const { 683 return _num_regions * ShenandoahHeapRegion::region_size_bytes(); 684 } 685 686 size_t ShenandoahHeap::soft_max_capacity() const { 687 size_t v = Atomic::load(&_soft_max_size); 688 assert(min_capacity() <= v && v <= max_capacity(), 689 "Should be in bounds: " SIZE_FORMAT " <= " SIZE_FORMAT " <= " SIZE_FORMAT, 690 min_capacity(), v, max_capacity()); 691 return v; 692 } 693 694 void ShenandoahHeap::set_soft_max_capacity(size_t v) { 695 assert(min_capacity() <= v && v <= max_capacity(), 696 "Should be in bounds: " SIZE_FORMAT " <= " SIZE_FORMAT " <= " SIZE_FORMAT, 697 min_capacity(), v, max_capacity()); 698 Atomic::store(&_soft_max_size, v); 699 } 700 701 size_t ShenandoahHeap::min_capacity() const { 702 return _minimum_size; 703 } 704 705 size_t ShenandoahHeap::initial_capacity() const { 706 return _initial_size; 707 } 708 709 bool ShenandoahHeap::is_in(const void* p) const { 710 HeapWord* heap_base = (HeapWord*) base(); 711 HeapWord* last_region_end = heap_base + ShenandoahHeapRegion::region_size_words() * num_regions(); 712 return p >= heap_base && p < last_region_end; 713 } 714 715 void ShenandoahHeap::op_uncommit(double shrink_before, size_t shrink_until) { 716 assert (ShenandoahUncommit, "should be enabled"); 717 718 // Application allocates from the beginning of the heap, and GC allocates at 719 // the end of it. It is more efficient to uncommit from the end, so that applications 720 // could enjoy the near committed regions. GC allocations are much less frequent, 721 // and therefore can accept the committing costs. 722 723 size_t count = 0; 724 for (size_t i = num_regions(); i > 0; i--) { // care about size_t underflow 725 ShenandoahHeapRegion* r = get_region(i - 1); 726 if (r->is_empty_committed() && (r->empty_time() < shrink_before)) { 727 ShenandoahHeapLocker locker(lock()); 728 if (r->is_empty_committed()) { 729 if (committed() < shrink_until + ShenandoahHeapRegion::region_size_bytes()) { 730 break; 731 } 732 733 r->make_uncommitted(); 734 count++; 735 } 736 } 737 SpinPause(); // allow allocators to take the lock 738 } 739 740 if (count > 0) { 741 control_thread()->notify_heap_changed(); 742 } 743 } 744 745 HeapWord* ShenandoahHeap::allocate_from_gclab_slow(Thread* thread, size_t size) { 746 // New object should fit the GCLAB size 747 size_t min_size = MAX2(size, PLAB::min_size()); 748 749 // Figure out size of new GCLAB, looking back at heuristics. Expand aggressively. 750 size_t new_size = ShenandoahThreadLocalData::gclab_size(thread) * 2; 751 new_size = MIN2(new_size, PLAB::max_size()); 752 new_size = MAX2(new_size, PLAB::min_size()); 753 754 // Record new heuristic value even if we take any shortcut. This captures 755 // the case when moderately-sized objects always take a shortcut. At some point, 756 // heuristics should catch up with them. 757 ShenandoahThreadLocalData::set_gclab_size(thread, new_size); 758 759 if (new_size < size) { 760 // New size still does not fit the object. Fall back to shared allocation. 761 // This avoids retiring perfectly good GCLABs, when we encounter a large object. 762 return nullptr; 763 } 764 765 // Retire current GCLAB, and allocate a new one. 766 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread); 767 gclab->retire(); 768 769 size_t actual_size = 0; 770 HeapWord* gclab_buf = allocate_new_gclab(min_size, new_size, &actual_size); 771 if (gclab_buf == nullptr) { 772 return nullptr; 773 } 774 775 assert (size <= actual_size, "allocation should fit"); 776 777 if (ZeroTLAB) { 778 // ..and clear it. 779 Copy::zero_to_words(gclab_buf, actual_size); 780 } else { 781 // ...and zap just allocated object. 782 #ifdef ASSERT 783 // Skip mangling the space corresponding to the object header to 784 // ensure that the returned space is not considered parsable by 785 // any concurrent GC thread. 786 size_t hdr_size = oopDesc::header_size(); 787 Copy::fill_to_words(gclab_buf + hdr_size, actual_size - hdr_size, badHeapWordVal); 788 #endif // ASSERT 789 } 790 gclab->set_buf(gclab_buf, actual_size); 791 return gclab->allocate(size); 792 } 793 794 HeapWord* ShenandoahHeap::allocate_new_tlab(size_t min_size, 795 size_t requested_size, 796 size_t* actual_size) { 797 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_tlab(min_size, requested_size); 798 HeapWord* res = allocate_memory(req); 799 if (res != nullptr) { 800 *actual_size = req.actual_size(); 801 } else { 802 *actual_size = 0; 803 } 804 return res; 805 } 806 807 HeapWord* ShenandoahHeap::allocate_new_gclab(size_t min_size, 808 size_t word_size, 809 size_t* actual_size) { 810 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_gclab(min_size, word_size); 811 HeapWord* res = allocate_memory(req); 812 if (res != nullptr) { 813 *actual_size = req.actual_size(); 814 } else { 815 *actual_size = 0; 816 } 817 return res; 818 } 819 820 HeapWord* ShenandoahHeap::allocate_memory(ShenandoahAllocRequest& req) { 821 intptr_t pacer_epoch = 0; 822 bool in_new_region = false; 823 HeapWord* result = nullptr; 824 825 if (req.is_mutator_alloc()) { 826 if (ShenandoahPacing) { 827 pacer()->pace_for_alloc(req.size()); 828 pacer_epoch = pacer()->epoch(); 829 } 830 831 if (!ShenandoahAllocFailureALot || !should_inject_alloc_failure()) { 832 result = allocate_memory_under_lock(req, in_new_region); 833 } 834 835 // Allocation failed, block until control thread reacted, then retry allocation. 836 // 837 // It might happen that one of the threads requesting allocation would unblock 838 // way later after GC happened, only to fail the second allocation, because 839 // other threads have already depleted the free storage. In this case, a better 840 // strategy is to try again, as long as GC makes progress. 841 // 842 // Then, we need to make sure the allocation was retried after at least one 843 // Full GC, which means we want to try more than ShenandoahFullGCThreshold times. 844 845 size_t tries = 0; 846 847 while (result == nullptr && _progress_last_gc.is_set()) { 848 tries++; 849 control_thread()->handle_alloc_failure(req); 850 result = allocate_memory_under_lock(req, in_new_region); 851 } 852 853 while (result == nullptr && tries <= ShenandoahFullGCThreshold) { 854 tries++; 855 control_thread()->handle_alloc_failure(req); 856 result = allocate_memory_under_lock(req, in_new_region); 857 } 858 859 } else { 860 assert(req.is_gc_alloc(), "Can only accept GC allocs here"); 861 result = allocate_memory_under_lock(req, in_new_region); 862 // Do not call handle_alloc_failure() here, because we cannot block. 863 // The allocation failure would be handled by the LRB slowpath with handle_alloc_failure_evac(). 864 } 865 866 if (in_new_region) { 867 control_thread()->notify_heap_changed(); 868 } 869 870 if (result != nullptr) { 871 size_t requested = req.size(); 872 size_t actual = req.actual_size(); 873 874 assert (req.is_lab_alloc() || (requested == actual), 875 "Only LAB allocations are elastic: %s, requested = " SIZE_FORMAT ", actual = " SIZE_FORMAT, 876 ShenandoahAllocRequest::alloc_type_to_string(req.type()), requested, actual); 877 878 if (req.is_mutator_alloc()) { 879 notify_mutator_alloc_words(actual, false); 880 881 // If we requested more than we were granted, give the rest back to pacer. 882 // This only matters if we are in the same pacing epoch: do not try to unpace 883 // over the budget for the other phase. 884 if (ShenandoahPacing && (pacer_epoch > 0) && (requested > actual)) { 885 pacer()->unpace_for_alloc(pacer_epoch, requested - actual); 886 } 887 } else { 888 increase_used(actual*HeapWordSize); 889 } 890 } 891 892 return result; 893 } 894 895 HeapWord* ShenandoahHeap::allocate_memory_under_lock(ShenandoahAllocRequest& req, bool& in_new_region) { 896 ShenandoahHeapLocker locker(lock()); 897 return _free_set->allocate(req, in_new_region); 898 } 899 900 HeapWord* ShenandoahHeap::mem_allocate(size_t size, 901 bool* gc_overhead_limit_was_exceeded) { 902 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_shared(size); 903 return allocate_memory(req); 904 } 905 906 MetaWord* ShenandoahHeap::satisfy_failed_metadata_allocation(ClassLoaderData* loader_data, 907 size_t size, 908 Metaspace::MetadataType mdtype) { 909 MetaWord* result; 910 911 // Inform metaspace OOM to GC heuristics if class unloading is possible. 912 if (heuristics()->can_unload_classes()) { 913 ShenandoahHeuristics* h = heuristics(); 914 h->record_metaspace_oom(); 915 } 916 917 // Expand and retry allocation 918 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype); 919 if (result != nullptr) { 920 return result; 921 } 922 923 // Start full GC 924 collect(GCCause::_metadata_GC_clear_soft_refs); 925 926 // Retry allocation 927 result = loader_data->metaspace_non_null()->allocate(size, mdtype); 928 if (result != nullptr) { 929 return result; 930 } 931 932 // Expand and retry allocation 933 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype); 934 if (result != nullptr) { 935 return result; 936 } 937 938 // Out of memory 939 return nullptr; 940 } 941 942 class ShenandoahConcurrentEvacuateRegionObjectClosure : public ObjectClosure { 943 private: 944 ShenandoahHeap* const _heap; 945 Thread* const _thread; 946 public: 947 ShenandoahConcurrentEvacuateRegionObjectClosure(ShenandoahHeap* heap) : 948 _heap(heap), _thread(Thread::current()) {} 949 950 void do_object(oop p) { 951 shenandoah_assert_marked(nullptr, p); 952 if (!p->is_forwarded()) { 953 _heap->evacuate_object(p, _thread); 954 } 955 } 956 }; 957 958 class ShenandoahEvacuationTask : public WorkerTask { 959 private: 960 ShenandoahHeap* const _sh; 961 ShenandoahCollectionSet* const _cs; 962 bool _concurrent; 963 public: 964 ShenandoahEvacuationTask(ShenandoahHeap* sh, 965 ShenandoahCollectionSet* cs, 966 bool concurrent) : 967 WorkerTask("Shenandoah Evacuation"), 968 _sh(sh), 969 _cs(cs), 970 _concurrent(concurrent) 971 {} 972 973 void work(uint worker_id) { 974 if (_concurrent) { 975 ShenandoahConcurrentWorkerSession worker_session(worker_id); 976 ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers); 977 ShenandoahEvacOOMScope oom_evac_scope; 978 do_work(); 979 } else { 980 ShenandoahParallelWorkerSession worker_session(worker_id); 981 ShenandoahEvacOOMScope oom_evac_scope; 982 do_work(); 983 } 984 } 985 986 private: 987 void do_work() { 988 ShenandoahConcurrentEvacuateRegionObjectClosure cl(_sh); 989 ShenandoahHeapRegion* r; 990 while ((r =_cs->claim_next()) != nullptr) { 991 assert(r->has_live(), "Region " SIZE_FORMAT " should have been reclaimed early", r->index()); 992 _sh->marked_object_iterate(r, &cl); 993 994 if (ShenandoahPacing) { 995 _sh->pacer()->report_evac(r->used() >> LogHeapWordSize); 996 } 997 998 if (_sh->check_cancelled_gc_and_yield(_concurrent)) { 999 break; 1000 } 1001 } 1002 } 1003 }; 1004 1005 void ShenandoahHeap::evacuate_collection_set(bool concurrent) { 1006 ShenandoahEvacuationTask task(this, _collection_set, concurrent); 1007 workers()->run_task(&task); 1008 } 1009 1010 void ShenandoahHeap::trash_cset_regions() { 1011 ShenandoahHeapLocker locker(lock()); 1012 1013 ShenandoahCollectionSet* set = collection_set(); 1014 ShenandoahHeapRegion* r; 1015 set->clear_current_index(); 1016 while ((r = set->next()) != nullptr) { 1017 r->make_trash(); 1018 } 1019 collection_set()->clear(); 1020 } 1021 1022 void ShenandoahHeap::print_heap_regions_on(outputStream* st) const { 1023 st->print_cr("Heap Regions:"); 1024 st->print_cr("EU=empty-uncommitted, EC=empty-committed, R=regular, H=humongous start, HC=humongous continuation, CS=collection set, T=trash, P=pinned"); 1025 st->print_cr("BTE=bottom/top/end, U=used, T=TLAB allocs, G=GCLAB allocs, S=shared allocs, L=live data"); 1026 st->print_cr("R=root, CP=critical pins, TAMS=top-at-mark-start, UWM=update watermark"); 1027 st->print_cr("SN=alloc sequence number"); 1028 1029 for (size_t i = 0; i < num_regions(); i++) { 1030 get_region(i)->print_on(st); 1031 } 1032 } 1033 1034 void ShenandoahHeap::trash_humongous_region_at(ShenandoahHeapRegion* start) { 1035 assert(start->is_humongous_start(), "reclaim regions starting with the first one"); 1036 1037 oop humongous_obj = cast_to_oop(start->bottom()); 1038 size_t size = humongous_obj->size(); 1039 size_t required_regions = ShenandoahHeapRegion::required_regions(size * HeapWordSize); 1040 size_t index = start->index() + required_regions - 1; 1041 1042 assert(!start->has_live(), "liveness must be zero"); 1043 1044 for(size_t i = 0; i < required_regions; i++) { 1045 // Reclaim from tail. Otherwise, assertion fails when printing region to trace log, 1046 // as it expects that every region belongs to a humongous region starting with a humongous start region. 1047 ShenandoahHeapRegion* region = get_region(index --); 1048 1049 assert(region->is_humongous(), "expect correct humongous start or continuation"); 1050 assert(!region->is_cset(), "Humongous region should not be in collection set"); 1051 1052 region->make_trash_immediate(); 1053 } 1054 } 1055 1056 class ShenandoahCheckCleanGCLABClosure : public ThreadClosure { 1057 public: 1058 ShenandoahCheckCleanGCLABClosure() {} 1059 void do_thread(Thread* thread) { 1060 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread); 1061 assert(gclab != nullptr, "GCLAB should be initialized for %s", thread->name()); 1062 assert(gclab->words_remaining() == 0, "GCLAB should not need retirement"); 1063 } 1064 }; 1065 1066 class ShenandoahRetireGCLABClosure : public ThreadClosure { 1067 private: 1068 bool const _resize; 1069 public: 1070 ShenandoahRetireGCLABClosure(bool resize) : _resize(resize) {} 1071 void do_thread(Thread* thread) { 1072 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread); 1073 assert(gclab != nullptr, "GCLAB should be initialized for %s", thread->name()); 1074 gclab->retire(); 1075 if (_resize && ShenandoahThreadLocalData::gclab_size(thread) > 0) { 1076 ShenandoahThreadLocalData::set_gclab_size(thread, 0); 1077 } 1078 } 1079 }; 1080 1081 void ShenandoahHeap::labs_make_parsable() { 1082 assert(UseTLAB, "Only call with UseTLAB"); 1083 1084 ShenandoahRetireGCLABClosure cl(false); 1085 1086 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) { 1087 ThreadLocalAllocBuffer& tlab = t->tlab(); 1088 tlab.make_parsable(); 1089 cl.do_thread(t); 1090 } 1091 1092 workers()->threads_do(&cl); 1093 } 1094 1095 void ShenandoahHeap::tlabs_retire(bool resize) { 1096 assert(UseTLAB, "Only call with UseTLAB"); 1097 assert(!resize || ResizeTLAB, "Only call for resize when ResizeTLAB is enabled"); 1098 1099 ThreadLocalAllocStats stats; 1100 1101 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) { 1102 ThreadLocalAllocBuffer& tlab = t->tlab(); 1103 tlab.retire(&stats); 1104 if (resize) { 1105 tlab.resize(); 1106 } 1107 } 1108 1109 stats.publish(); 1110 1111 #ifdef ASSERT 1112 ShenandoahCheckCleanGCLABClosure cl; 1113 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) { 1114 cl.do_thread(t); 1115 } 1116 workers()->threads_do(&cl); 1117 #endif 1118 } 1119 1120 void ShenandoahHeap::gclabs_retire(bool resize) { 1121 assert(UseTLAB, "Only call with UseTLAB"); 1122 assert(!resize || ResizeTLAB, "Only call for resize when ResizeTLAB is enabled"); 1123 1124 ShenandoahRetireGCLABClosure cl(resize); 1125 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) { 1126 cl.do_thread(t); 1127 } 1128 workers()->threads_do(&cl); 1129 1130 if (safepoint_workers() != nullptr) { 1131 safepoint_workers()->threads_do(&cl); 1132 } 1133 } 1134 1135 // Returns size in bytes 1136 size_t ShenandoahHeap::unsafe_max_tlab_alloc(Thread *thread) const { 1137 if (ShenandoahElasticTLAB) { 1138 // With Elastic TLABs, return the max allowed size, and let the allocation path 1139 // figure out the safe size for current allocation. 1140 return ShenandoahHeapRegion::max_tlab_size_bytes(); 1141 } else { 1142 return MIN2(_free_set->unsafe_peek_free(), ShenandoahHeapRegion::max_tlab_size_bytes()); 1143 } 1144 } 1145 1146 size_t ShenandoahHeap::max_tlab_size() const { 1147 // Returns size in words 1148 return ShenandoahHeapRegion::max_tlab_size_words(); 1149 } 1150 1151 void ShenandoahHeap::collect(GCCause::Cause cause) { 1152 control_thread()->request_gc(cause); 1153 } 1154 1155 void ShenandoahHeap::do_full_collection(bool clear_all_soft_refs) { 1156 //assert(false, "Shouldn't need to do full collections"); 1157 } 1158 1159 HeapWord* ShenandoahHeap::block_start(const void* addr) const { 1160 ShenandoahHeapRegion* r = heap_region_containing(addr); 1161 if (r != nullptr) { 1162 return r->block_start(addr); 1163 } 1164 return nullptr; 1165 } 1166 1167 bool ShenandoahHeap::block_is_obj(const HeapWord* addr) const { 1168 ShenandoahHeapRegion* r = heap_region_containing(addr); 1169 return r->block_is_obj(addr); 1170 } 1171 1172 bool ShenandoahHeap::print_location(outputStream* st, void* addr) const { 1173 return BlockLocationPrinter<ShenandoahHeap>::print_location(st, addr); 1174 } 1175 1176 void ShenandoahHeap::prepare_for_verify() { 1177 if (SafepointSynchronize::is_at_safepoint() && UseTLAB) { 1178 labs_make_parsable(); 1179 } 1180 } 1181 1182 void ShenandoahHeap::gc_threads_do(ThreadClosure* tcl) const { 1183 tcl->do_thread(_control_thread); 1184 workers()->threads_do(tcl); 1185 if (_safepoint_workers != nullptr) { 1186 _safepoint_workers->threads_do(tcl); 1187 } 1188 } 1189 1190 void ShenandoahHeap::print_tracing_info() const { 1191 LogTarget(Info, gc, stats) lt; 1192 if (lt.is_enabled()) { 1193 ResourceMark rm; 1194 LogStream ls(lt); 1195 1196 phase_timings()->print_global_on(&ls); 1197 1198 ls.cr(); 1199 ls.cr(); 1200 1201 shenandoah_policy()->print_gc_stats(&ls); 1202 1203 ls.cr(); 1204 ls.cr(); 1205 } 1206 } 1207 1208 void ShenandoahHeap::verify(VerifyOption vo) { 1209 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) { 1210 if (ShenandoahVerify) { 1211 verifier()->verify_generic(vo); 1212 } else { 1213 // TODO: Consider allocating verification bitmaps on demand, 1214 // and turn this on unconditionally. 1215 } 1216 } 1217 } 1218 size_t ShenandoahHeap::tlab_capacity(Thread *thr) const { 1219 return _free_set->capacity(); 1220 } 1221 1222 class ObjectIterateScanRootClosure : public BasicOopIterateClosure { 1223 private: 1224 MarkBitMap* _bitmap; 1225 ShenandoahScanObjectStack* _oop_stack; 1226 ShenandoahHeap* const _heap; 1227 ShenandoahMarkingContext* const _marking_context; 1228 1229 template <class T> 1230 void do_oop_work(T* p) { 1231 T o = RawAccess<>::oop_load(p); 1232 if (!CompressedOops::is_null(o)) { 1233 oop obj = CompressedOops::decode_not_null(o); 1234 if (_heap->is_concurrent_weak_root_in_progress() && !_marking_context->is_marked(obj)) { 1235 // There may be dead oops in weak roots in concurrent root phase, do not touch them. 1236 return; 1237 } 1238 obj = ShenandoahBarrierSet::barrier_set()->load_reference_barrier(obj); 1239 1240 assert(oopDesc::is_oop(obj), "must be a valid oop"); 1241 if (!_bitmap->is_marked(obj)) { 1242 _bitmap->mark(obj); 1243 _oop_stack->push(obj); 1244 } 1245 } 1246 } 1247 public: 1248 ObjectIterateScanRootClosure(MarkBitMap* bitmap, ShenandoahScanObjectStack* oop_stack) : 1249 _bitmap(bitmap), _oop_stack(oop_stack), _heap(ShenandoahHeap::heap()), 1250 _marking_context(_heap->marking_context()) {} 1251 void do_oop(oop* p) { do_oop_work(p); } 1252 void do_oop(narrowOop* p) { do_oop_work(p); } 1253 }; 1254 1255 /* 1256 * This is public API, used in preparation of object_iterate(). 1257 * Since we don't do linear scan of heap in object_iterate() (see comment below), we don't 1258 * need to make the heap parsable. For Shenandoah-internal linear heap scans that we can 1259 * control, we call SH::tlabs_retire, SH::gclabs_retire. 1260 */ 1261 void ShenandoahHeap::ensure_parsability(bool retire_tlabs) { 1262 // No-op. 1263 } 1264 1265 /* 1266 * Iterates objects in the heap. This is public API, used for, e.g., heap dumping. 1267 * 1268 * We cannot safely iterate objects by doing a linear scan at random points in time. Linear 1269 * scanning needs to deal with dead objects, which may have dead Klass* pointers (e.g. 1270 * calling oopDesc::size() would crash) or dangling reference fields (crashes) etc. Linear 1271 * scanning therefore depends on having a valid marking bitmap to support it. However, we only 1272 * have a valid marking bitmap after successful marking. In particular, we *don't* have a valid 1273 * marking bitmap during marking, after aborted marking or during/after cleanup (when we just 1274 * wiped the bitmap in preparation for next marking). 1275 * 1276 * For all those reasons, we implement object iteration as a single marking traversal, reporting 1277 * objects as we mark+traverse through the heap, starting from GC roots. JVMTI IterateThroughHeap 1278 * is allowed to report dead objects, but is not required to do so. 1279 */ 1280 void ShenandoahHeap::object_iterate(ObjectClosure* cl) { 1281 // Reset bitmap 1282 if (!prepare_aux_bitmap_for_iteration()) 1283 return; 1284 1285 ShenandoahScanObjectStack oop_stack; 1286 ObjectIterateScanRootClosure oops(&_aux_bit_map, &oop_stack); 1287 // Seed the stack with root scan 1288 scan_roots_for_iteration(&oop_stack, &oops); 1289 1290 // Work through the oop stack to traverse heap 1291 while (! oop_stack.is_empty()) { 1292 oop obj = oop_stack.pop(); 1293 assert(oopDesc::is_oop(obj), "must be a valid oop"); 1294 cl->do_object(obj); 1295 obj->oop_iterate(&oops); 1296 } 1297 1298 assert(oop_stack.is_empty(), "should be empty"); 1299 // Reclaim bitmap 1300 reclaim_aux_bitmap_for_iteration(); 1301 } 1302 1303 bool ShenandoahHeap::prepare_aux_bitmap_for_iteration() { 1304 assert(SafepointSynchronize::is_at_safepoint(), "safe iteration is only available during safepoints"); 1305 1306 if (!_aux_bitmap_region_special && !os::commit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size(), false)) { 1307 log_warning(gc)("Could not commit native memory for auxiliary marking bitmap for heap iteration"); 1308 return false; 1309 } 1310 // Reset bitmap 1311 _aux_bit_map.clear(); 1312 return true; 1313 } 1314 1315 void ShenandoahHeap::scan_roots_for_iteration(ShenandoahScanObjectStack* oop_stack, ObjectIterateScanRootClosure* oops) { 1316 // Process GC roots according to current GC cycle 1317 // This populates the work stack with initial objects 1318 // It is important to relinquish the associated locks before diving 1319 // into heap dumper 1320 uint n_workers = safepoint_workers() != nullptr ? safepoint_workers()->active_workers() : 1; 1321 ShenandoahHeapIterationRootScanner rp(n_workers); 1322 rp.roots_do(oops); 1323 } 1324 1325 void ShenandoahHeap::reclaim_aux_bitmap_for_iteration() { 1326 if (!_aux_bitmap_region_special && !os::uncommit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size())) { 1327 log_warning(gc)("Could not uncommit native memory for auxiliary marking bitmap for heap iteration"); 1328 } 1329 } 1330 1331 // Closure for parallelly iterate objects 1332 class ShenandoahObjectIterateParScanClosure : public BasicOopIterateClosure { 1333 private: 1334 MarkBitMap* _bitmap; 1335 ShenandoahObjToScanQueue* _queue; 1336 ShenandoahHeap* const _heap; 1337 ShenandoahMarkingContext* const _marking_context; 1338 1339 template <class T> 1340 void do_oop_work(T* p) { 1341 T o = RawAccess<>::oop_load(p); 1342 if (!CompressedOops::is_null(o)) { 1343 oop obj = CompressedOops::decode_not_null(o); 1344 if (_heap->is_concurrent_weak_root_in_progress() && !_marking_context->is_marked(obj)) { 1345 // There may be dead oops in weak roots in concurrent root phase, do not touch them. 1346 return; 1347 } 1348 obj = ShenandoahBarrierSet::barrier_set()->load_reference_barrier(obj); 1349 1350 assert(oopDesc::is_oop(obj), "Must be a valid oop"); 1351 if (_bitmap->par_mark(obj)) { 1352 _queue->push(ShenandoahMarkTask(obj)); 1353 } 1354 } 1355 } 1356 public: 1357 ShenandoahObjectIterateParScanClosure(MarkBitMap* bitmap, ShenandoahObjToScanQueue* q) : 1358 _bitmap(bitmap), _queue(q), _heap(ShenandoahHeap::heap()), 1359 _marking_context(_heap->marking_context()) {} 1360 void do_oop(oop* p) { do_oop_work(p); } 1361 void do_oop(narrowOop* p) { do_oop_work(p); } 1362 }; 1363 1364 // Object iterator for parallel heap iteraion. 1365 // The root scanning phase happenes in construction as a preparation of 1366 // parallel marking queues. 1367 // Every worker processes it's own marking queue. work-stealing is used 1368 // to balance workload. 1369 class ShenandoahParallelObjectIterator : public ParallelObjectIteratorImpl { 1370 private: 1371 uint _num_workers; 1372 bool _init_ready; 1373 MarkBitMap* _aux_bit_map; 1374 ShenandoahHeap* _heap; 1375 ShenandoahScanObjectStack _roots_stack; // global roots stack 1376 ShenandoahObjToScanQueueSet* _task_queues; 1377 public: 1378 ShenandoahParallelObjectIterator(uint num_workers, MarkBitMap* bitmap) : 1379 _num_workers(num_workers), 1380 _init_ready(false), 1381 _aux_bit_map(bitmap), 1382 _heap(ShenandoahHeap::heap()) { 1383 // Initialize bitmap 1384 _init_ready = _heap->prepare_aux_bitmap_for_iteration(); 1385 if (!_init_ready) { 1386 return; 1387 } 1388 1389 ObjectIterateScanRootClosure oops(_aux_bit_map, &_roots_stack); 1390 _heap->scan_roots_for_iteration(&_roots_stack, &oops); 1391 1392 _init_ready = prepare_worker_queues(); 1393 } 1394 1395 ~ShenandoahParallelObjectIterator() { 1396 // Reclaim bitmap 1397 _heap->reclaim_aux_bitmap_for_iteration(); 1398 // Reclaim queue for workers 1399 if (_task_queues!= nullptr) { 1400 for (uint i = 0; i < _num_workers; ++i) { 1401 ShenandoahObjToScanQueue* q = _task_queues->queue(i); 1402 if (q != nullptr) { 1403 delete q; 1404 _task_queues->register_queue(i, nullptr); 1405 } 1406 } 1407 delete _task_queues; 1408 _task_queues = nullptr; 1409 } 1410 } 1411 1412 virtual void object_iterate(ObjectClosure* cl, uint worker_id) { 1413 if (_init_ready) { 1414 object_iterate_parallel(cl, worker_id, _task_queues); 1415 } 1416 } 1417 1418 private: 1419 // Divide global root_stack into worker queues 1420 bool prepare_worker_queues() { 1421 _task_queues = new ShenandoahObjToScanQueueSet((int) _num_workers); 1422 // Initialize queues for every workers 1423 for (uint i = 0; i < _num_workers; ++i) { 1424 ShenandoahObjToScanQueue* task_queue = new ShenandoahObjToScanQueue(); 1425 _task_queues->register_queue(i, task_queue); 1426 } 1427 // Divide roots among the workers. Assume that object referencing distribution 1428 // is related with root kind, use round-robin to make every worker have same chance 1429 // to process every kind of roots 1430 size_t roots_num = _roots_stack.size(); 1431 if (roots_num == 0) { 1432 // No work to do 1433 return false; 1434 } 1435 1436 for (uint j = 0; j < roots_num; j++) { 1437 uint stack_id = j % _num_workers; 1438 oop obj = _roots_stack.pop(); 1439 _task_queues->queue(stack_id)->push(ShenandoahMarkTask(obj)); 1440 } 1441 return true; 1442 } 1443 1444 void object_iterate_parallel(ObjectClosure* cl, 1445 uint worker_id, 1446 ShenandoahObjToScanQueueSet* queue_set) { 1447 assert(SafepointSynchronize::is_at_safepoint(), "safe iteration is only available during safepoints"); 1448 assert(queue_set != nullptr, "task queue must not be null"); 1449 1450 ShenandoahObjToScanQueue* q = queue_set->queue(worker_id); 1451 assert(q != nullptr, "object iterate queue must not be null"); 1452 1453 ShenandoahMarkTask t; 1454 ShenandoahObjectIterateParScanClosure oops(_aux_bit_map, q); 1455 1456 // Work through the queue to traverse heap. 1457 // Steal when there is no task in queue. 1458 while (q->pop(t) || queue_set->steal(worker_id, t)) { 1459 oop obj = t.obj(); 1460 assert(oopDesc::is_oop(obj), "must be a valid oop"); 1461 cl->do_object(obj); 1462 obj->oop_iterate(&oops); 1463 } 1464 assert(q->is_empty(), "should be empty"); 1465 } 1466 }; 1467 1468 ParallelObjectIteratorImpl* ShenandoahHeap::parallel_object_iterator(uint workers) { 1469 return new ShenandoahParallelObjectIterator(workers, &_aux_bit_map); 1470 } 1471 1472 // Keep alive an object that was loaded with AS_NO_KEEPALIVE. 1473 void ShenandoahHeap::keep_alive(oop obj) { 1474 if (is_concurrent_mark_in_progress() && (obj != nullptr)) { 1475 ShenandoahBarrierSet::barrier_set()->enqueue(obj); 1476 } 1477 } 1478 1479 void ShenandoahHeap::heap_region_iterate(ShenandoahHeapRegionClosure* blk) const { 1480 for (size_t i = 0; i < num_regions(); i++) { 1481 ShenandoahHeapRegion* current = get_region(i); 1482 blk->heap_region_do(current); 1483 } 1484 } 1485 1486 class ShenandoahParallelHeapRegionTask : public WorkerTask { 1487 private: 1488 ShenandoahHeap* const _heap; 1489 ShenandoahHeapRegionClosure* const _blk; 1490 1491 shenandoah_padding(0); 1492 volatile size_t _index; 1493 shenandoah_padding(1); 1494 1495 public: 1496 ShenandoahParallelHeapRegionTask(ShenandoahHeapRegionClosure* blk) : 1497 WorkerTask("Shenandoah Parallel Region Operation"), 1498 _heap(ShenandoahHeap::heap()), _blk(blk), _index(0) {} 1499 1500 void work(uint worker_id) { 1501 ShenandoahParallelWorkerSession worker_session(worker_id); 1502 size_t stride = ShenandoahParallelRegionStride; 1503 1504 size_t max = _heap->num_regions(); 1505 while (Atomic::load(&_index) < max) { 1506 size_t cur = Atomic::fetch_then_add(&_index, stride, memory_order_relaxed); 1507 size_t start = cur; 1508 size_t end = MIN2(cur + stride, max); 1509 if (start >= max) break; 1510 1511 for (size_t i = cur; i < end; i++) { 1512 ShenandoahHeapRegion* current = _heap->get_region(i); 1513 _blk->heap_region_do(current); 1514 } 1515 } 1516 } 1517 }; 1518 1519 void ShenandoahHeap::parallel_heap_region_iterate(ShenandoahHeapRegionClosure* blk) const { 1520 assert(blk->is_thread_safe(), "Only thread-safe closures here"); 1521 if (num_regions() > ShenandoahParallelRegionStride) { 1522 ShenandoahParallelHeapRegionTask task(blk); 1523 workers()->run_task(&task); 1524 } else { 1525 heap_region_iterate(blk); 1526 } 1527 } 1528 1529 class ShenandoahInitMarkUpdateRegionStateClosure : public ShenandoahHeapRegionClosure { 1530 private: 1531 ShenandoahMarkingContext* const _ctx; 1532 public: 1533 ShenandoahInitMarkUpdateRegionStateClosure() : _ctx(ShenandoahHeap::heap()->marking_context()) {} 1534 1535 void heap_region_do(ShenandoahHeapRegion* r) { 1536 assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->index()); 1537 if (r->is_active()) { 1538 // Check if region needs updating its TAMS. We have updated it already during concurrent 1539 // reset, so it is very likely we don't need to do another write here. 1540 if (_ctx->top_at_mark_start(r) != r->top()) { 1541 _ctx->capture_top_at_mark_start(r); 1542 } 1543 } else { 1544 assert(_ctx->top_at_mark_start(r) == r->top(), 1545 "Region " SIZE_FORMAT " should already have correct TAMS", r->index()); 1546 } 1547 } 1548 1549 bool is_thread_safe() { return true; } 1550 }; 1551 1552 class ShenandoahRendezvousClosure : public HandshakeClosure { 1553 public: 1554 inline ShenandoahRendezvousClosure() : HandshakeClosure("ShenandoahRendezvous") {} 1555 inline void do_thread(Thread* thread) {} 1556 }; 1557 1558 void ShenandoahHeap::rendezvous_threads() { 1559 ShenandoahRendezvousClosure cl; 1560 Handshake::execute(&cl); 1561 } 1562 1563 void ShenandoahHeap::recycle_trash() { 1564 free_set()->recycle_trash(); 1565 } 1566 1567 class ShenandoahResetUpdateRegionStateClosure : public ShenandoahHeapRegionClosure { 1568 private: 1569 ShenandoahMarkingContext* const _ctx; 1570 public: 1571 ShenandoahResetUpdateRegionStateClosure() : _ctx(ShenandoahHeap::heap()->marking_context()) {} 1572 1573 void heap_region_do(ShenandoahHeapRegion* r) { 1574 if (r->is_active()) { 1575 // Reset live data and set TAMS optimistically. We would recheck these under the pause 1576 // anyway to capture any updates that happened since now. 1577 r->clear_live_data(); 1578 _ctx->capture_top_at_mark_start(r); 1579 } 1580 } 1581 1582 bool is_thread_safe() { return true; } 1583 }; 1584 1585 void ShenandoahHeap::prepare_gc() { 1586 reset_mark_bitmap(); 1587 1588 ShenandoahResetUpdateRegionStateClosure cl; 1589 parallel_heap_region_iterate(&cl); 1590 } 1591 1592 class ShenandoahFinalMarkUpdateRegionStateClosure : public ShenandoahHeapRegionClosure { 1593 private: 1594 ShenandoahMarkingContext* const _ctx; 1595 ShenandoahHeapLock* const _lock; 1596 1597 public: 1598 ShenandoahFinalMarkUpdateRegionStateClosure() : 1599 _ctx(ShenandoahHeap::heap()->complete_marking_context()), _lock(ShenandoahHeap::heap()->lock()) {} 1600 1601 void heap_region_do(ShenandoahHeapRegion* r) { 1602 if (r->is_active()) { 1603 // All allocations past TAMS are implicitly live, adjust the region data. 1604 // Bitmaps/TAMS are swapped at this point, so we need to poll complete bitmap. 1605 HeapWord *tams = _ctx->top_at_mark_start(r); 1606 HeapWord *top = r->top(); 1607 if (top > tams) { 1608 r->increase_live_data_alloc_words(pointer_delta(top, tams)); 1609 } 1610 1611 // We are about to select the collection set, make sure it knows about 1612 // current pinning status. Also, this allows trashing more regions that 1613 // now have their pinning status dropped. 1614 if (r->is_pinned()) { 1615 if (r->pin_count() == 0) { 1616 ShenandoahHeapLocker locker(_lock); 1617 r->make_unpinned(); 1618 } 1619 } else { 1620 if (r->pin_count() > 0) { 1621 ShenandoahHeapLocker locker(_lock); 1622 r->make_pinned(); 1623 } 1624 } 1625 1626 // Remember limit for updating refs. It's guaranteed that we get no 1627 // from-space-refs written from here on. 1628 r->set_update_watermark_at_safepoint(r->top()); 1629 } else { 1630 assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->index()); 1631 assert(_ctx->top_at_mark_start(r) == r->top(), 1632 "Region " SIZE_FORMAT " should have correct TAMS", r->index()); 1633 } 1634 } 1635 1636 bool is_thread_safe() { return true; } 1637 }; 1638 1639 void ShenandoahHeap::prepare_regions_and_collection_set(bool concurrent) { 1640 assert(!is_full_gc_in_progress(), "Only for concurrent and degenerated GC"); 1641 { 1642 ShenandoahGCPhase phase(concurrent ? ShenandoahPhaseTimings::final_update_region_states : 1643 ShenandoahPhaseTimings::degen_gc_final_update_region_states); 1644 ShenandoahFinalMarkUpdateRegionStateClosure cl; 1645 parallel_heap_region_iterate(&cl); 1646 1647 assert_pinned_region_status(); 1648 } 1649 1650 { 1651 ShenandoahGCPhase phase(concurrent ? ShenandoahPhaseTimings::choose_cset : 1652 ShenandoahPhaseTimings::degen_gc_choose_cset); 1653 ShenandoahHeapLocker locker(lock()); 1654 _collection_set->clear(); 1655 heuristics()->choose_collection_set(_collection_set); 1656 } 1657 1658 { 1659 ShenandoahGCPhase phase(concurrent ? ShenandoahPhaseTimings::final_rebuild_freeset : 1660 ShenandoahPhaseTimings::degen_gc_final_rebuild_freeset); 1661 ShenandoahHeapLocker locker(lock()); 1662 _free_set->rebuild(); 1663 } 1664 } 1665 1666 void ShenandoahHeap::do_class_unloading() { 1667 _unloader.unload(); 1668 } 1669 1670 void ShenandoahHeap::stw_weak_refs(bool full_gc) { 1671 // Weak refs processing 1672 ShenandoahPhaseTimings::Phase phase = full_gc ? ShenandoahPhaseTimings::full_gc_weakrefs 1673 : ShenandoahPhaseTimings::degen_gc_weakrefs; 1674 ShenandoahTimingsTracker t(phase); 1675 ShenandoahGCWorkerPhase worker_phase(phase); 1676 ref_processor()->process_references(phase, workers(), false /* concurrent */); 1677 } 1678 1679 void ShenandoahHeap::prepare_update_heap_references(bool concurrent) { 1680 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint"); 1681 1682 // Evacuation is over, no GCLABs are needed anymore. GCLABs are under URWM, so we need to 1683 // make them parsable for update code to work correctly. Plus, we can compute new sizes 1684 // for future GCLABs here. 1685 if (UseTLAB) { 1686 ShenandoahGCPhase phase(concurrent ? 1687 ShenandoahPhaseTimings::init_update_refs_manage_gclabs : 1688 ShenandoahPhaseTimings::degen_gc_init_update_refs_manage_gclabs); 1689 gclabs_retire(ResizeTLAB); 1690 } 1691 1692 _update_refs_iterator.reset(); 1693 } 1694 1695 void ShenandoahHeap::set_gc_state_all_threads(char state) { 1696 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) { 1697 ShenandoahThreadLocalData::set_gc_state(t, state); 1698 } 1699 } 1700 1701 void ShenandoahHeap::set_gc_state_mask(uint mask, bool value) { 1702 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should really be Shenandoah safepoint"); 1703 _gc_state.set_cond(mask, value); 1704 set_gc_state_all_threads(_gc_state.raw_value()); 1705 } 1706 1707 void ShenandoahHeap::set_concurrent_mark_in_progress(bool in_progress) { 1708 assert(!has_forwarded_objects(), "Not expected before/after mark phase"); 1709 set_gc_state_mask(MARKING, in_progress); 1710 ShenandoahBarrierSet::satb_mark_queue_set().set_active_all_threads(in_progress, !in_progress); 1711 } 1712 1713 void ShenandoahHeap::set_evacuation_in_progress(bool in_progress) { 1714 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Only call this at safepoint"); 1715 set_gc_state_mask(EVACUATION, in_progress); 1716 } 1717 1718 void ShenandoahHeap::set_concurrent_strong_root_in_progress(bool in_progress) { 1719 if (in_progress) { 1720 _concurrent_strong_root_in_progress.set(); 1721 } else { 1722 _concurrent_strong_root_in_progress.unset(); 1723 } 1724 } 1725 1726 void ShenandoahHeap::set_concurrent_weak_root_in_progress(bool cond) { 1727 set_gc_state_mask(WEAK_ROOTS, cond); 1728 } 1729 1730 GCTracer* ShenandoahHeap::tracer() { 1731 return shenandoah_policy()->tracer(); 1732 } 1733 1734 size_t ShenandoahHeap::tlab_used(Thread* thread) const { 1735 return _free_set->used(); 1736 } 1737 1738 bool ShenandoahHeap::try_cancel_gc() { 1739 jbyte prev = _cancelled_gc.cmpxchg(CANCELLED, CANCELLABLE); 1740 return prev == CANCELLABLE; 1741 } 1742 1743 void ShenandoahHeap::cancel_gc(GCCause::Cause cause) { 1744 if (try_cancel_gc()) { 1745 FormatBuffer<> msg("Cancelling GC: %s", GCCause::to_string(cause)); 1746 log_info(gc)("%s", msg.buffer()); 1747 Events::log(Thread::current(), "%s", msg.buffer()); 1748 } 1749 } 1750 1751 uint ShenandoahHeap::max_workers() { 1752 return _max_workers; 1753 } 1754 1755 void ShenandoahHeap::stop() { 1756 // The shutdown sequence should be able to terminate when GC is running. 1757 1758 // Step 0. Notify policy to disable event recording. 1759 _shenandoah_policy->record_shutdown(); 1760 1761 // Step 1. Notify control thread that we are in shutdown. 1762 // Note that we cannot do that with stop(), because stop() is blocking and waits for the actual shutdown. 1763 // Doing stop() here would wait for the normal GC cycle to complete, never falling through to cancel below. 1764 control_thread()->prepare_for_graceful_shutdown(); 1765 1766 // Step 2. Notify GC workers that we are cancelling GC. 1767 cancel_gc(GCCause::_shenandoah_stop_vm); 1768 1769 // Step 3. Wait until GC worker exits normally. 1770 control_thread()->stop(); 1771 } 1772 1773 void ShenandoahHeap::stw_unload_classes(bool full_gc) { 1774 if (!unload_classes()) return; 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 CodeCache::UnloadingScope scope(is_alive.is_alive_closure()); 1782 ShenandoahGCPhase gc_phase(phase); 1783 ShenandoahGCWorkerPhase worker_phase(phase); 1784 bool purged_class = SystemDictionary::do_unloading(gc_timer()); 1785 1786 uint num_workers = _workers->active_workers(); 1787 ShenandoahClassUnloadingTask unlink_task(phase, num_workers, purged_class); 1788 _workers->run_task(&unlink_task); 1789 } 1790 1791 { 1792 ShenandoahGCPhase phase(full_gc ? 1793 ShenandoahPhaseTimings::full_gc_purge_cldg : 1794 ShenandoahPhaseTimings::degen_gc_purge_cldg); 1795 ClassLoaderDataGraph::purge(/*at_safepoint*/true); 1796 } 1797 // Resize and verify metaspace 1798 MetaspaceGC::compute_new_size(); 1799 DEBUG_ONLY(MetaspaceUtils::verify();) 1800 } 1801 1802 // Weak roots are either pre-evacuated (final mark) or updated (final updaterefs), 1803 // so they should not have forwarded oops. 1804 // However, we do need to "null" dead oops in the roots, if can not be done 1805 // in concurrent cycles. 1806 void ShenandoahHeap::stw_process_weak_roots(bool full_gc) { 1807 uint num_workers = _workers->active_workers(); 1808 ShenandoahPhaseTimings::Phase timing_phase = full_gc ? 1809 ShenandoahPhaseTimings::full_gc_purge_weak_par : 1810 ShenandoahPhaseTimings::degen_gc_purge_weak_par; 1811 ShenandoahGCPhase phase(timing_phase); 1812 ShenandoahGCWorkerPhase worker_phase(timing_phase); 1813 // Cleanup weak roots 1814 if (has_forwarded_objects()) { 1815 ShenandoahForwardedIsAliveClosure is_alive; 1816 ShenandoahUpdateRefsClosure keep_alive; 1817 ShenandoahParallelWeakRootsCleaningTask<ShenandoahForwardedIsAliveClosure, ShenandoahUpdateRefsClosure> 1818 cleaning_task(timing_phase, &is_alive, &keep_alive, num_workers); 1819 _workers->run_task(&cleaning_task); 1820 } else { 1821 ShenandoahIsAliveClosure is_alive; 1822 #ifdef ASSERT 1823 ShenandoahAssertNotForwardedClosure verify_cl; 1824 ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, ShenandoahAssertNotForwardedClosure> 1825 cleaning_task(timing_phase, &is_alive, &verify_cl, num_workers); 1826 #else 1827 ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, DoNothingClosure> 1828 cleaning_task(timing_phase, &is_alive, &do_nothing_cl, num_workers); 1829 #endif 1830 _workers->run_task(&cleaning_task); 1831 } 1832 } 1833 1834 void ShenandoahHeap::parallel_cleaning(bool full_gc) { 1835 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint"); 1836 assert(is_stw_gc_in_progress(), "Only for Degenerated and Full GC"); 1837 ShenandoahGCPhase phase(full_gc ? 1838 ShenandoahPhaseTimings::full_gc_purge : 1839 ShenandoahPhaseTimings::degen_gc_purge); 1840 stw_weak_refs(full_gc); 1841 stw_process_weak_roots(full_gc); 1842 stw_unload_classes(full_gc); 1843 } 1844 1845 void ShenandoahHeap::set_has_forwarded_objects(bool cond) { 1846 set_gc_state_mask(HAS_FORWARDED, cond); 1847 } 1848 1849 void ShenandoahHeap::set_unload_classes(bool uc) { 1850 _unload_classes.set_cond(uc); 1851 } 1852 1853 bool ShenandoahHeap::unload_classes() const { 1854 return _unload_classes.is_set(); 1855 } 1856 1857 address ShenandoahHeap::in_cset_fast_test_addr() { 1858 ShenandoahHeap* heap = ShenandoahHeap::heap(); 1859 assert(heap->collection_set() != nullptr, "Sanity"); 1860 return (address) heap->collection_set()->biased_map_address(); 1861 } 1862 1863 address ShenandoahHeap::cancelled_gc_addr() { 1864 return (address) ShenandoahHeap::heap()->_cancelled_gc.addr_of(); 1865 } 1866 1867 address ShenandoahHeap::gc_state_addr() { 1868 return (address) ShenandoahHeap::heap()->_gc_state.addr_of(); 1869 } 1870 1871 size_t ShenandoahHeap::bytes_allocated_since_gc_start() { 1872 return Atomic::load(&_bytes_allocated_since_gc_start); 1873 } 1874 1875 void ShenandoahHeap::reset_bytes_allocated_since_gc_start() { 1876 Atomic::store(&_bytes_allocated_since_gc_start, (size_t)0); 1877 } 1878 1879 void ShenandoahHeap::set_degenerated_gc_in_progress(bool in_progress) { 1880 _degenerated_gc_in_progress.set_cond(in_progress); 1881 } 1882 1883 void ShenandoahHeap::set_full_gc_in_progress(bool in_progress) { 1884 _full_gc_in_progress.set_cond(in_progress); 1885 } 1886 1887 void ShenandoahHeap::set_full_gc_move_in_progress(bool in_progress) { 1888 assert (is_full_gc_in_progress(), "should be"); 1889 _full_gc_move_in_progress.set_cond(in_progress); 1890 } 1891 1892 void ShenandoahHeap::set_update_refs_in_progress(bool in_progress) { 1893 set_gc_state_mask(UPDATEREFS, in_progress); 1894 } 1895 1896 void ShenandoahHeap::register_nmethod(nmethod* nm) { 1897 ShenandoahCodeRoots::register_nmethod(nm); 1898 } 1899 1900 void ShenandoahHeap::unregister_nmethod(nmethod* nm) { 1901 ShenandoahCodeRoots::unregister_nmethod(nm); 1902 } 1903 1904 void ShenandoahHeap::pin_object(JavaThread* thr, oop o) { 1905 heap_region_containing(o)->record_pin(); 1906 } 1907 1908 void ShenandoahHeap::unpin_object(JavaThread* thr, oop o) { 1909 ShenandoahHeapRegion* r = heap_region_containing(o); 1910 assert(r != nullptr, "Sanity"); 1911 assert(r->pin_count() > 0, "Region " SIZE_FORMAT " should have non-zero pins", r->index()); 1912 r->record_unpin(); 1913 } 1914 1915 void ShenandoahHeap::sync_pinned_region_status() { 1916 ShenandoahHeapLocker locker(lock()); 1917 1918 for (size_t i = 0; i < num_regions(); i++) { 1919 ShenandoahHeapRegion *r = get_region(i); 1920 if (r->is_active()) { 1921 if (r->is_pinned()) { 1922 if (r->pin_count() == 0) { 1923 r->make_unpinned(); 1924 } 1925 } else { 1926 if (r->pin_count() > 0) { 1927 r->make_pinned(); 1928 } 1929 } 1930 } 1931 } 1932 1933 assert_pinned_region_status(); 1934 } 1935 1936 #ifdef ASSERT 1937 void ShenandoahHeap::assert_pinned_region_status() { 1938 for (size_t i = 0; i < num_regions(); i++) { 1939 ShenandoahHeapRegion* r = get_region(i); 1940 assert((r->is_pinned() && r->pin_count() > 0) || (!r->is_pinned() && r->pin_count() == 0), 1941 "Region " SIZE_FORMAT " pinning status is inconsistent", i); 1942 } 1943 } 1944 #endif 1945 1946 ConcurrentGCTimer* ShenandoahHeap::gc_timer() const { 1947 return _gc_timer; 1948 } 1949 1950 void ShenandoahHeap::prepare_concurrent_roots() { 1951 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint"); 1952 assert(!is_stw_gc_in_progress(), "Only concurrent GC"); 1953 set_concurrent_strong_root_in_progress(!collection_set()->is_empty()); 1954 set_concurrent_weak_root_in_progress(true); 1955 if (unload_classes()) { 1956 _unloader.prepare(); 1957 } 1958 } 1959 1960 void ShenandoahHeap::finish_concurrent_roots() { 1961 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint"); 1962 assert(!is_stw_gc_in_progress(), "Only concurrent GC"); 1963 if (unload_classes()) { 1964 _unloader.finish(); 1965 } 1966 } 1967 1968 #ifdef ASSERT 1969 void ShenandoahHeap::assert_gc_workers(uint nworkers) { 1970 assert(nworkers > 0 && nworkers <= max_workers(), "Sanity"); 1971 1972 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) { 1973 if (UseDynamicNumberOfGCThreads) { 1974 assert(nworkers <= ParallelGCThreads, "Cannot use more than it has"); 1975 } else { 1976 // Use ParallelGCThreads inside safepoints 1977 assert(nworkers == ParallelGCThreads, "Use ParallelGCThreads within safepoints"); 1978 } 1979 } else { 1980 if (UseDynamicNumberOfGCThreads) { 1981 assert(nworkers <= ConcGCThreads, "Cannot use more than it has"); 1982 } else { 1983 // Use ConcGCThreads outside safepoints 1984 assert(nworkers == ConcGCThreads, "Use ConcGCThreads outside safepoints"); 1985 } 1986 } 1987 } 1988 #endif 1989 1990 ShenandoahVerifier* ShenandoahHeap::verifier() { 1991 guarantee(ShenandoahVerify, "Should be enabled"); 1992 assert (_verifier != nullptr, "sanity"); 1993 return _verifier; 1994 } 1995 1996 template<bool CONCURRENT> 1997 class ShenandoahUpdateHeapRefsTask : public WorkerTask { 1998 private: 1999 ShenandoahHeap* _heap; 2000 ShenandoahRegionIterator* _regions; 2001 public: 2002 ShenandoahUpdateHeapRefsTask(ShenandoahRegionIterator* regions) : 2003 WorkerTask("Shenandoah Update References"), 2004 _heap(ShenandoahHeap::heap()), 2005 _regions(regions) { 2006 } 2007 2008 void work(uint worker_id) { 2009 if (CONCURRENT) { 2010 ShenandoahConcurrentWorkerSession worker_session(worker_id); 2011 ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers); 2012 do_work<ShenandoahConcUpdateRefsClosure>(); 2013 } else { 2014 ShenandoahParallelWorkerSession worker_session(worker_id); 2015 do_work<ShenandoahSTWUpdateRefsClosure>(); 2016 } 2017 } 2018 2019 private: 2020 template<class T> 2021 void do_work() { 2022 T cl; 2023 ShenandoahHeapRegion* r = _regions->next(); 2024 ShenandoahMarkingContext* const ctx = _heap->complete_marking_context(); 2025 while (r != nullptr) { 2026 HeapWord* update_watermark = r->get_update_watermark(); 2027 assert (update_watermark >= r->bottom(), "sanity"); 2028 if (r->is_active() && !r->is_cset()) { 2029 _heap->marked_object_oop_iterate(r, &cl, update_watermark); 2030 } 2031 if (ShenandoahPacing) { 2032 _heap->pacer()->report_updaterefs(pointer_delta(update_watermark, r->bottom())); 2033 } 2034 if (_heap->check_cancelled_gc_and_yield(CONCURRENT)) { 2035 return; 2036 } 2037 r = _regions->next(); 2038 } 2039 } 2040 }; 2041 2042 void ShenandoahHeap::update_heap_references(bool concurrent) { 2043 assert(!is_full_gc_in_progress(), "Only for concurrent and degenerated GC"); 2044 2045 if (concurrent) { 2046 ShenandoahUpdateHeapRefsTask<true> task(&_update_refs_iterator); 2047 workers()->run_task(&task); 2048 } else { 2049 ShenandoahUpdateHeapRefsTask<false> task(&_update_refs_iterator); 2050 workers()->run_task(&task); 2051 } 2052 } 2053 2054 2055 class ShenandoahFinalUpdateRefsUpdateRegionStateClosure : public ShenandoahHeapRegionClosure { 2056 private: 2057 ShenandoahHeapLock* const _lock; 2058 2059 public: 2060 ShenandoahFinalUpdateRefsUpdateRegionStateClosure() : _lock(ShenandoahHeap::heap()->lock()) {} 2061 2062 void heap_region_do(ShenandoahHeapRegion* r) { 2063 // Drop unnecessary "pinned" state from regions that does not have CP marks 2064 // anymore, as this would allow trashing them. 2065 2066 if (r->is_active()) { 2067 if (r->is_pinned()) { 2068 if (r->pin_count() == 0) { 2069 ShenandoahHeapLocker locker(_lock); 2070 r->make_unpinned(); 2071 } 2072 } else { 2073 if (r->pin_count() > 0) { 2074 ShenandoahHeapLocker locker(_lock); 2075 r->make_pinned(); 2076 } 2077 } 2078 } 2079 } 2080 2081 bool is_thread_safe() { return true; } 2082 }; 2083 2084 void ShenandoahHeap::update_heap_region_states(bool concurrent) { 2085 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint"); 2086 assert(!is_full_gc_in_progress(), "Only for concurrent and degenerated GC"); 2087 2088 { 2089 ShenandoahGCPhase phase(concurrent ? 2090 ShenandoahPhaseTimings::final_update_refs_update_region_states : 2091 ShenandoahPhaseTimings::degen_gc_final_update_refs_update_region_states); 2092 ShenandoahFinalUpdateRefsUpdateRegionStateClosure cl; 2093 parallel_heap_region_iterate(&cl); 2094 2095 assert_pinned_region_status(); 2096 } 2097 2098 { 2099 ShenandoahGCPhase phase(concurrent ? 2100 ShenandoahPhaseTimings::final_update_refs_trash_cset : 2101 ShenandoahPhaseTimings::degen_gc_final_update_refs_trash_cset); 2102 trash_cset_regions(); 2103 } 2104 } 2105 2106 void ShenandoahHeap::rebuild_free_set(bool concurrent) { 2107 { 2108 ShenandoahGCPhase phase(concurrent ? 2109 ShenandoahPhaseTimings::final_update_refs_rebuild_freeset : 2110 ShenandoahPhaseTimings::degen_gc_final_update_refs_rebuild_freeset); 2111 ShenandoahHeapLocker locker(lock()); 2112 _free_set->rebuild(); 2113 } 2114 } 2115 2116 void ShenandoahHeap::print_extended_on(outputStream *st) const { 2117 print_on(st); 2118 print_heap_regions_on(st); 2119 } 2120 2121 bool ShenandoahHeap::is_bitmap_slice_committed(ShenandoahHeapRegion* r, bool skip_self) { 2122 size_t slice = r->index() / _bitmap_regions_per_slice; 2123 2124 size_t regions_from = _bitmap_regions_per_slice * slice; 2125 size_t regions_to = MIN2(num_regions(), _bitmap_regions_per_slice * (slice + 1)); 2126 for (size_t g = regions_from; g < regions_to; g++) { 2127 assert (g / _bitmap_regions_per_slice == slice, "same slice"); 2128 if (skip_self && g == r->index()) continue; 2129 if (get_region(g)->is_committed()) { 2130 return true; 2131 } 2132 } 2133 return false; 2134 } 2135 2136 bool ShenandoahHeap::commit_bitmap_slice(ShenandoahHeapRegion* r) { 2137 shenandoah_assert_heaplocked(); 2138 2139 // Bitmaps in special regions do not need commits 2140 if (_bitmap_region_special) { 2141 return true; 2142 } 2143 2144 if (is_bitmap_slice_committed(r, true)) { 2145 // Some other region from the group is already committed, meaning the bitmap 2146 // slice is already committed, we exit right away. 2147 return true; 2148 } 2149 2150 // Commit the bitmap slice: 2151 size_t slice = r->index() / _bitmap_regions_per_slice; 2152 size_t off = _bitmap_bytes_per_slice * slice; 2153 size_t len = _bitmap_bytes_per_slice; 2154 char* start = (char*) _bitmap_region.start() + off; 2155 2156 if (!os::commit_memory(start, len, false)) { 2157 return false; 2158 } 2159 2160 if (AlwaysPreTouch) { 2161 os::pretouch_memory(start, start + len, _pretouch_bitmap_page_size); 2162 } 2163 2164 return true; 2165 } 2166 2167 bool ShenandoahHeap::uncommit_bitmap_slice(ShenandoahHeapRegion *r) { 2168 shenandoah_assert_heaplocked(); 2169 2170 // Bitmaps in special regions do not need uncommits 2171 if (_bitmap_region_special) { 2172 return true; 2173 } 2174 2175 if (is_bitmap_slice_committed(r, true)) { 2176 // Some other region from the group is still committed, meaning the bitmap 2177 // slice is should stay committed, exit right away. 2178 return true; 2179 } 2180 2181 // Uncommit the bitmap slice: 2182 size_t slice = r->index() / _bitmap_regions_per_slice; 2183 size_t off = _bitmap_bytes_per_slice * slice; 2184 size_t len = _bitmap_bytes_per_slice; 2185 if (!os::uncommit_memory((char*)_bitmap_region.start() + off, len)) { 2186 return false; 2187 } 2188 return true; 2189 } 2190 2191 void ShenandoahHeap::safepoint_synchronize_begin() { 2192 if (ShenandoahSuspendibleWorkers) { 2193 SuspendibleThreadSet::synchronize(); 2194 } 2195 } 2196 2197 void ShenandoahHeap::safepoint_synchronize_end() { 2198 if (ShenandoahSuspendibleWorkers) { 2199 SuspendibleThreadSet::desynchronize(); 2200 } 2201 } 2202 2203 void ShenandoahHeap::entry_uncommit(double shrink_before, size_t shrink_until) { 2204 static const char *msg = "Concurrent uncommit"; 2205 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_uncommit, true /* log_heap_usage */); 2206 EventMark em("%s", msg); 2207 2208 op_uncommit(shrink_before, shrink_until); 2209 } 2210 2211 void ShenandoahHeap::try_inject_alloc_failure() { 2212 if (ShenandoahAllocFailureALot && !cancelled_gc() && ((os::random() % 1000) > 950)) { 2213 _inject_alloc_failure.set(); 2214 os::naked_short_sleep(1); 2215 if (cancelled_gc()) { 2216 log_info(gc)("Allocation failure was successfully injected"); 2217 } 2218 } 2219 } 2220 2221 bool ShenandoahHeap::should_inject_alloc_failure() { 2222 return _inject_alloc_failure.is_set() && _inject_alloc_failure.try_unset(); 2223 } 2224 2225 void ShenandoahHeap::initialize_serviceability() { 2226 _memory_pool = new ShenandoahMemoryPool(this); 2227 _cycle_memory_manager.add_pool(_memory_pool); 2228 _stw_memory_manager.add_pool(_memory_pool); 2229 } 2230 2231 GrowableArray<GCMemoryManager*> ShenandoahHeap::memory_managers() { 2232 GrowableArray<GCMemoryManager*> memory_managers(2); 2233 memory_managers.append(&_cycle_memory_manager); 2234 memory_managers.append(&_stw_memory_manager); 2235 return memory_managers; 2236 } 2237 2238 GrowableArray<MemoryPool*> ShenandoahHeap::memory_pools() { 2239 GrowableArray<MemoryPool*> memory_pools(1); 2240 memory_pools.append(_memory_pool); 2241 return memory_pools; 2242 } 2243 2244 MemoryUsage ShenandoahHeap::memory_usage() { 2245 return _memory_pool->get_memory_usage(); 2246 } 2247 2248 ShenandoahRegionIterator::ShenandoahRegionIterator() : 2249 _heap(ShenandoahHeap::heap()), 2250 _index(0) {} 2251 2252 ShenandoahRegionIterator::ShenandoahRegionIterator(ShenandoahHeap* heap) : 2253 _heap(heap), 2254 _index(0) {} 2255 2256 void ShenandoahRegionIterator::reset() { 2257 _index = 0; 2258 } 2259 2260 bool ShenandoahRegionIterator::has_next() const { 2261 return _index < _heap->num_regions(); 2262 } 2263 2264 char ShenandoahHeap::gc_state() const { 2265 return _gc_state.raw_value(); 2266 } 2267 2268 ShenandoahLiveData* ShenandoahHeap::get_liveness_cache(uint worker_id) { 2269 #ifdef ASSERT 2270 assert(_liveness_cache != nullptr, "sanity"); 2271 assert(worker_id < _max_workers, "sanity"); 2272 for (uint i = 0; i < num_regions(); i++) { 2273 assert(_liveness_cache[worker_id][i] == 0, "liveness cache should be empty"); 2274 } 2275 #endif 2276 return _liveness_cache[worker_id]; 2277 } 2278 2279 void ShenandoahHeap::flush_liveness_cache(uint worker_id) { 2280 assert(worker_id < _max_workers, "sanity"); 2281 assert(_liveness_cache != nullptr, "sanity"); 2282 ShenandoahLiveData* ld = _liveness_cache[worker_id]; 2283 for (uint i = 0; i < num_regions(); i++) { 2284 ShenandoahLiveData live = ld[i]; 2285 if (live > 0) { 2286 ShenandoahHeapRegion* r = get_region(i); 2287 r->increase_live_data_gc_words(live); 2288 ld[i] = 0; 2289 } 2290 } 2291 } 2292 2293 bool ShenandoahHeap::requires_barriers(stackChunkOop obj) const { 2294 if (is_idle()) return false; 2295 2296 // Objects allocated after marking start are implicitly alive, don't need any barriers during 2297 // marking phase. 2298 if (is_concurrent_mark_in_progress() && 2299 !marking_context()->allocated_after_mark_start(obj)) { 2300 return true; 2301 } 2302 2303 // Can not guarantee obj is deeply good. 2304 if (has_forwarded_objects()) { 2305 return true; 2306 } 2307 2308 return false; 2309 }