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/slidingForwarding.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/shenandoahStringDedup.hpp" 63 #include "gc/shenandoah/shenandoahSTWMark.hpp" 64 #include "gc/shenandoah/shenandoahUtils.hpp" 65 #include "gc/shenandoah/shenandoahVerifier.hpp" 66 #include "gc/shenandoah/shenandoahCodeRoots.hpp" 67 #include "gc/shenandoah/shenandoahVMOperations.hpp" 68 #include "gc/shenandoah/shenandoahWorkGroup.hpp" 69 #include "gc/shenandoah/shenandoahWorkerPolicy.hpp" 70 #include "gc/shenandoah/mode/shenandoahIUMode.hpp" 71 #include "gc/shenandoah/mode/shenandoahPassiveMode.hpp" 72 #include "gc/shenandoah/mode/shenandoahSATBMode.hpp" 73 #if INCLUDE_JFR 74 #include "gc/shenandoah/shenandoahJfrSupport.hpp" 75 #endif 76 77 #include "classfile/systemDictionary.hpp" 78 #include "code/codeCache.hpp" 79 #include "memory/classLoaderMetaspace.hpp" 80 #include "memory/metaspaceUtils.hpp" 81 #include "oops/compressedOops.inline.hpp" 82 #include "prims/jvmtiTagMap.hpp" 83 #include "runtime/atomic.hpp" 84 #include "runtime/globals.hpp" 85 #include "runtime/interfaceSupport.inline.hpp" 86 #include "runtime/java.hpp" 87 #include "runtime/orderAccess.hpp" 88 #include "runtime/safepointMechanism.hpp" 89 #include "runtime/vmThread.hpp" 90 #include "services/mallocTracker.hpp" 91 #include "services/memTracker.hpp" 92 #include "utilities/events.hpp" 93 #include "utilities/powerOfTwo.hpp" 94 95 class ShenandoahPretouchHeapTask : public WorkerTask { 96 private: 97 ShenandoahRegionIterator _regions; 98 const size_t _page_size; 99 public: 100 ShenandoahPretouchHeapTask(size_t page_size) : 101 WorkerTask("Shenandoah Pretouch Heap"), 102 _page_size(page_size) {} 103 104 virtual void work(uint worker_id) { 105 ShenandoahHeapRegion* r = _regions.next(); 106 while (r != nullptr) { 107 if (r->is_committed()) { 108 os::pretouch_memory(r->bottom(), r->end(), _page_size); 109 } 110 r = _regions.next(); 111 } 112 } 113 }; 114 115 class ShenandoahPretouchBitmapTask : public WorkerTask { 116 private: 117 ShenandoahRegionIterator _regions; 118 char* _bitmap_base; 119 const size_t _bitmap_size; 120 const size_t _page_size; 121 public: 122 ShenandoahPretouchBitmapTask(char* bitmap_base, size_t bitmap_size, size_t page_size) : 123 WorkerTask("Shenandoah Pretouch Bitmap"), 124 _bitmap_base(bitmap_base), 125 _bitmap_size(bitmap_size), 126 _page_size(page_size) {} 127 128 virtual void work(uint worker_id) { 129 ShenandoahHeapRegion* r = _regions.next(); 130 while (r != nullptr) { 131 size_t start = r->index() * ShenandoahHeapRegion::region_size_bytes() / MarkBitMap::heap_map_factor(); 132 size_t end = (r->index() + 1) * ShenandoahHeapRegion::region_size_bytes() / MarkBitMap::heap_map_factor(); 133 assert (end <= _bitmap_size, "end is sane: " SIZE_FORMAT " < " SIZE_FORMAT, end, _bitmap_size); 134 135 if (r->is_committed()) { 136 os::pretouch_memory(_bitmap_base + start, _bitmap_base + end, _page_size); 137 } 138 139 r = _regions.next(); 140 } 141 } 142 }; 143 144 jint ShenandoahHeap::initialize() { 145 // 146 // Figure out heap sizing 147 // 148 149 size_t init_byte_size = InitialHeapSize; 150 size_t min_byte_size = MinHeapSize; 151 size_t max_byte_size = MaxHeapSize; 152 size_t heap_alignment = HeapAlignment; 153 154 size_t reg_size_bytes = ShenandoahHeapRegion::region_size_bytes(); 155 156 Universe::check_alignment(max_byte_size, reg_size_bytes, "Shenandoah heap"); 157 Universe::check_alignment(init_byte_size, reg_size_bytes, "Shenandoah heap"); 158 159 _num_regions = ShenandoahHeapRegion::region_count(); 160 assert(_num_regions == (max_byte_size / reg_size_bytes), 161 "Regions should cover entire heap exactly: " SIZE_FORMAT " != " SIZE_FORMAT "/" SIZE_FORMAT, 162 _num_regions, max_byte_size, reg_size_bytes); 163 164 // Now we know the number of regions, initialize the heuristics. 165 initialize_heuristics(); 166 167 size_t num_committed_regions = init_byte_size / reg_size_bytes; 168 num_committed_regions = MIN2(num_committed_regions, _num_regions); 169 assert(num_committed_regions <= _num_regions, "sanity"); 170 _initial_size = num_committed_regions * reg_size_bytes; 171 172 size_t num_min_regions = min_byte_size / reg_size_bytes; 173 num_min_regions = MIN2(num_min_regions, _num_regions); 174 assert(num_min_regions <= _num_regions, "sanity"); 175 _minimum_size = num_min_regions * reg_size_bytes; 176 177 // Default to max heap size. 178 _soft_max_size = _num_regions * reg_size_bytes; 179 180 _committed = _initial_size; 181 182 size_t heap_page_size = UseLargePages ? os::large_page_size() : os::vm_page_size(); 183 size_t bitmap_page_size = UseLargePages ? os::large_page_size() : os::vm_page_size(); 184 size_t region_page_size = UseLargePages ? os::large_page_size() : os::vm_page_size(); 185 186 // 187 // Reserve and commit memory for heap 188 // 189 190 ReservedHeapSpace heap_rs = Universe::reserve_heap(max_byte_size, heap_alignment); 191 initialize_reserved_region(heap_rs); 192 _heap_region = MemRegion((HeapWord*)heap_rs.base(), heap_rs.size() / HeapWordSize); 193 _heap_region_special = heap_rs.special(); 194 195 assert((((size_t) base()) & ShenandoahHeapRegion::region_size_bytes_mask()) == 0, 196 "Misaligned heap: " PTR_FORMAT, p2i(base())); 197 198 _forwarding = new SlidingForwarding(_heap_region, ShenandoahHeapRegion::region_size_words_shift()); 199 200 #if SHENANDOAH_OPTIMIZED_MARKTASK 201 // The optimized ShenandoahMarkTask takes some bits away from the full object bits. 202 // Fail if we ever attempt to address more than we can. 203 if ((uintptr_t)heap_rs.end() >= ShenandoahMarkTask::max_addressable()) { 204 FormatBuffer<512> buf("Shenandoah reserved [" PTR_FORMAT ", " PTR_FORMAT") for the heap, \n" 205 "but max object address is " PTR_FORMAT ". Try to reduce heap size, or try other \n" 206 "VM options that allocate heap at lower addresses (HeapBaseMinAddress, AllocateHeapAt, etc).", 207 p2i(heap_rs.base()), p2i(heap_rs.end()), ShenandoahMarkTask::max_addressable()); 208 vm_exit_during_initialization("Fatal Error", buf); 209 } 210 #endif 211 212 ReservedSpace sh_rs = heap_rs.first_part(max_byte_size); 213 if (!_heap_region_special) { 214 os::commit_memory_or_exit(sh_rs.base(), _initial_size, heap_alignment, false, 215 "Cannot commit heap memory"); 216 } 217 218 // 219 // Reserve and commit memory for bitmap(s) 220 // 221 222 _bitmap_size = ShenandoahMarkBitMap::compute_size(heap_rs.size()); 223 _bitmap_size = align_up(_bitmap_size, bitmap_page_size); 224 225 size_t bitmap_bytes_per_region = reg_size_bytes / ShenandoahMarkBitMap::heap_map_factor(); 226 227 guarantee(bitmap_bytes_per_region != 0, 228 "Bitmap bytes per region should not be zero"); 229 guarantee(is_power_of_2(bitmap_bytes_per_region), 230 "Bitmap bytes per region should be power of two: " SIZE_FORMAT, bitmap_bytes_per_region); 231 232 if (bitmap_page_size > bitmap_bytes_per_region) { 233 _bitmap_regions_per_slice = bitmap_page_size / bitmap_bytes_per_region; 234 _bitmap_bytes_per_slice = bitmap_page_size; 235 } else { 236 _bitmap_regions_per_slice = 1; 237 _bitmap_bytes_per_slice = bitmap_bytes_per_region; 238 } 239 240 guarantee(_bitmap_regions_per_slice >= 1, 241 "Should have at least one region per slice: " SIZE_FORMAT, 242 _bitmap_regions_per_slice); 243 244 guarantee(((_bitmap_bytes_per_slice) % bitmap_page_size) == 0, 245 "Bitmap slices should be page-granular: bps = " SIZE_FORMAT ", page size = " SIZE_FORMAT, 246 _bitmap_bytes_per_slice, bitmap_page_size); 247 248 ReservedSpace bitmap(_bitmap_size, bitmap_page_size); 249 MemTracker::record_virtual_memory_type(bitmap.base(), mtGC); 250 _bitmap_region = MemRegion((HeapWord*) bitmap.base(), bitmap.size() / HeapWordSize); 251 _bitmap_region_special = bitmap.special(); 252 253 size_t bitmap_init_commit = _bitmap_bytes_per_slice * 254 align_up(num_committed_regions, _bitmap_regions_per_slice) / _bitmap_regions_per_slice; 255 bitmap_init_commit = MIN2(_bitmap_size, bitmap_init_commit); 256 if (!_bitmap_region_special) { 257 os::commit_memory_or_exit((char *) _bitmap_region.start(), bitmap_init_commit, bitmap_page_size, false, 258 "Cannot commit bitmap memory"); 259 } 260 261 _marking_context = new ShenandoahMarkingContext(_heap_region, _bitmap_region, _num_regions, _max_workers); 262 263 if (ShenandoahVerify) { 264 ReservedSpace verify_bitmap(_bitmap_size, bitmap_page_size); 265 if (!verify_bitmap.special()) { 266 os::commit_memory_or_exit(verify_bitmap.base(), verify_bitmap.size(), bitmap_page_size, false, 267 "Cannot commit verification bitmap memory"); 268 } 269 MemTracker::record_virtual_memory_type(verify_bitmap.base(), mtGC); 270 MemRegion verify_bitmap_region = MemRegion((HeapWord *) verify_bitmap.base(), verify_bitmap.size() / HeapWordSize); 271 _verification_bit_map.initialize(_heap_region, verify_bitmap_region); 272 _verifier = new ShenandoahVerifier(this, &_verification_bit_map); 273 } 274 275 // Reserve aux bitmap for use in object_iterate(). We don't commit it here. 276 ReservedSpace aux_bitmap(_bitmap_size, bitmap_page_size); 277 MemTracker::record_virtual_memory_type(aux_bitmap.base(), mtGC); 278 _aux_bitmap_region = MemRegion((HeapWord*) aux_bitmap.base(), aux_bitmap.size() / HeapWordSize); 279 _aux_bitmap_region_special = aux_bitmap.special(); 280 _aux_bit_map.initialize(_heap_region, _aux_bitmap_region); 281 282 // 283 // Create regions and region sets 284 // 285 size_t region_align = align_up(sizeof(ShenandoahHeapRegion), SHENANDOAH_CACHE_LINE_SIZE); 286 size_t region_storage_size = align_up(region_align * _num_regions, region_page_size); 287 region_storage_size = align_up(region_storage_size, os::vm_allocation_granularity()); 288 289 ReservedSpace region_storage(region_storage_size, region_page_size); 290 MemTracker::record_virtual_memory_type(region_storage.base(), mtGC); 291 if (!region_storage.special()) { 292 os::commit_memory_or_exit(region_storage.base(), region_storage_size, region_page_size, false, 293 "Cannot commit region memory"); 294 } 295 296 // Try to fit the collection set bitmap at lower addresses. This optimizes code generation for cset checks. 297 // Go up until a sensible limit (subject to encoding constraints) and try to reserve the space there. 298 // If not successful, bite a bullet and allocate at whatever address. 299 { 300 size_t cset_align = MAX2<size_t>(os::vm_page_size(), os::vm_allocation_granularity()); 301 size_t cset_size = align_up(((size_t) sh_rs.base() + sh_rs.size()) >> ShenandoahHeapRegion::region_size_bytes_shift(), cset_align); 302 303 uintptr_t min = round_up_power_of_2(cset_align); 304 uintptr_t max = (1u << 30u); 305 306 for (uintptr_t addr = min; addr <= max; addr <<= 1u) { 307 char* req_addr = (char*)addr; 308 assert(is_aligned(req_addr, cset_align), "Should be aligned"); 309 ReservedSpace cset_rs(cset_size, cset_align, os::vm_page_size(), req_addr); 310 if (cset_rs.is_reserved()) { 311 assert(cset_rs.base() == req_addr, "Allocated where requested: " PTR_FORMAT ", " PTR_FORMAT, p2i(cset_rs.base()), addr); 312 _collection_set = new ShenandoahCollectionSet(this, cset_rs, sh_rs.base()); 313 break; 314 } 315 } 316 317 if (_collection_set == nullptr) { 318 ReservedSpace cset_rs(cset_size, cset_align, os::vm_page_size()); 319 _collection_set = new ShenandoahCollectionSet(this, cset_rs, sh_rs.base()); 320 } 321 } 322 323 _regions = NEW_C_HEAP_ARRAY(ShenandoahHeapRegion*, _num_regions, mtGC); 324 _free_set = new ShenandoahFreeSet(this, _num_regions); 325 326 { 327 ShenandoahHeapLocker locker(lock()); 328 329 for (size_t i = 0; i < _num_regions; i++) { 330 HeapWord* start = (HeapWord*)sh_rs.base() + ShenandoahHeapRegion::region_size_words() * i; 331 bool is_committed = i < num_committed_regions; 332 void* loc = region_storage.base() + i * region_align; 333 334 ShenandoahHeapRegion* r = new (loc) ShenandoahHeapRegion(start, i, is_committed); 335 assert(is_aligned(r, SHENANDOAH_CACHE_LINE_SIZE), "Sanity"); 336 337 _marking_context->initialize_top_at_mark_start(r); 338 _regions[i] = r; 339 assert(!collection_set()->is_in(i), "New region should not be in collection set"); 340 } 341 342 // Initialize to complete 343 _marking_context->mark_complete(); 344 345 _free_set->rebuild(); 346 } 347 348 if (AlwaysPreTouch) { 349 // For NUMA, it is important to pre-touch the storage under bitmaps with worker threads, 350 // before initialize() below zeroes it with initializing thread. For any given region, 351 // we touch the region and the corresponding bitmaps from the same thread. 352 ShenandoahPushWorkerScope scope(workers(), _max_workers, false); 353 354 _pretouch_heap_page_size = heap_page_size; 355 _pretouch_bitmap_page_size = bitmap_page_size; 356 357 #ifdef LINUX 358 // UseTransparentHugePages would madvise that backing memory can be coalesced into huge 359 // pages. But, the kernel needs to know that every small page is used, in order to coalesce 360 // them into huge one. Therefore, we need to pretouch with smaller pages. 361 if (UseTransparentHugePages) { 362 _pretouch_heap_page_size = (size_t)os::vm_page_size(); 363 _pretouch_bitmap_page_size = (size_t)os::vm_page_size(); 364 } 365 #endif 366 367 // OS memory managers may want to coalesce back-to-back pages. Make their jobs 368 // simpler by pre-touching continuous spaces (heap and bitmap) separately. 369 370 ShenandoahPretouchBitmapTask bcl(bitmap.base(), _bitmap_size, _pretouch_bitmap_page_size); 371 _workers->run_task(&bcl); 372 373 ShenandoahPretouchHeapTask hcl(_pretouch_heap_page_size); 374 _workers->run_task(&hcl); 375 } 376 377 // 378 // Initialize the rest of GC subsystems 379 // 380 381 _liveness_cache = NEW_C_HEAP_ARRAY(ShenandoahLiveData*, _max_workers, mtGC); 382 for (uint worker = 0; worker < _max_workers; worker++) { 383 _liveness_cache[worker] = NEW_C_HEAP_ARRAY(ShenandoahLiveData, _num_regions, mtGC); 384 Copy::fill_to_bytes(_liveness_cache[worker], _num_regions * sizeof(ShenandoahLiveData)); 385 } 386 387 // There should probably be Shenandoah-specific options for these, 388 // just as there are G1-specific options. 389 { 390 ShenandoahSATBMarkQueueSet& satbqs = ShenandoahBarrierSet::satb_mark_queue_set(); 391 satbqs.set_process_completed_buffers_threshold(20); // G1SATBProcessCompletedThreshold 392 satbqs.set_buffer_enqueue_threshold_percentage(60); // G1SATBBufferEnqueueingThresholdPercent 393 } 394 395 _monitoring_support = new ShenandoahMonitoringSupport(this); 396 _phase_timings = new ShenandoahPhaseTimings(max_workers()); 397 ShenandoahCodeRoots::initialize(); 398 399 if (ShenandoahPacing) { 400 _pacer = new ShenandoahPacer(this); 401 _pacer->setup_for_idle(); 402 } else { 403 _pacer = nullptr; 404 } 405 406 _control_thread = new ShenandoahControlThread(); 407 408 ShenandoahInitLogger::print(); 409 410 return JNI_OK; 411 } 412 413 void ShenandoahHeap::initialize_mode() { 414 if (ShenandoahGCMode != nullptr) { 415 if (strcmp(ShenandoahGCMode, "satb") == 0) { 416 _gc_mode = new ShenandoahSATBMode(); 417 } else if (strcmp(ShenandoahGCMode, "iu") == 0) { 418 _gc_mode = new ShenandoahIUMode(); 419 } else if (strcmp(ShenandoahGCMode, "passive") == 0) { 420 _gc_mode = new ShenandoahPassiveMode(); 421 } else { 422 vm_exit_during_initialization("Unknown -XX:ShenandoahGCMode option"); 423 } 424 } else { 425 vm_exit_during_initialization("Unknown -XX:ShenandoahGCMode option (null)"); 426 } 427 _gc_mode->initialize_flags(); 428 if (_gc_mode->is_diagnostic() && !UnlockDiagnosticVMOptions) { 429 vm_exit_during_initialization( 430 err_msg("GC mode \"%s\" is diagnostic, and must be enabled via -XX:+UnlockDiagnosticVMOptions.", 431 _gc_mode->name())); 432 } 433 if (_gc_mode->is_experimental() && !UnlockExperimentalVMOptions) { 434 vm_exit_during_initialization( 435 err_msg("GC mode \"%s\" is experimental, and must be enabled via -XX:+UnlockExperimentalVMOptions.", 436 _gc_mode->name())); 437 } 438 } 439 440 void ShenandoahHeap::initialize_heuristics() { 441 assert(_gc_mode != nullptr, "Must be initialized"); 442 _heuristics = _gc_mode->initialize_heuristics(); 443 444 if (_heuristics->is_diagnostic() && !UnlockDiagnosticVMOptions) { 445 vm_exit_during_initialization( 446 err_msg("Heuristics \"%s\" is diagnostic, and must be enabled via -XX:+UnlockDiagnosticVMOptions.", 447 _heuristics->name())); 448 } 449 if (_heuristics->is_experimental() && !UnlockExperimentalVMOptions) { 450 vm_exit_during_initialization( 451 err_msg("Heuristics \"%s\" is experimental, and must be enabled via -XX:+UnlockExperimentalVMOptions.", 452 _heuristics->name())); 453 } 454 } 455 456 #ifdef _MSC_VER 457 #pragma warning( push ) 458 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list 459 #endif 460 461 ShenandoahHeap::ShenandoahHeap(ShenandoahCollectorPolicy* policy) : 462 CollectedHeap(), 463 _initial_size(0), 464 _used(0), 465 _committed(0), 466 _bytes_allocated_since_gc_start(0), 467 _max_workers(MAX2(ConcGCThreads, ParallelGCThreads)), 468 _workers(nullptr), 469 _safepoint_workers(nullptr), 470 _heap_region_special(false), 471 _num_regions(0), 472 _regions(nullptr), 473 _update_refs_iterator(this), 474 _control_thread(nullptr), 475 _shenandoah_policy(policy), 476 _gc_mode(nullptr), 477 _heuristics(nullptr), 478 _free_set(nullptr), 479 _pacer(nullptr), 480 _verifier(nullptr), 481 _phase_timings(nullptr), 482 _monitoring_support(nullptr), 483 _memory_pool(nullptr), 484 _stw_memory_manager("Shenandoah Pauses", "end of GC pause"), 485 _cycle_memory_manager("Shenandoah Cycles", "end of GC cycle"), 486 _gc_timer(new ConcurrentGCTimer()), 487 _soft_ref_policy(), 488 _log_min_obj_alignment_in_bytes(LogMinObjAlignmentInBytes), 489 _ref_processor(new ShenandoahReferenceProcessor(MAX2(_max_workers, 1U))), 490 _marking_context(nullptr), 491 _bitmap_size(0), 492 _bitmap_regions_per_slice(0), 493 _bitmap_bytes_per_slice(0), 494 _bitmap_region_special(false), 495 _aux_bitmap_region_special(false), 496 _liveness_cache(nullptr), 497 _collection_set(nullptr) 498 { 499 // Initialize GC mode early, so we can adjust barrier support 500 initialize_mode(); 501 BarrierSet::set_barrier_set(new ShenandoahBarrierSet(this)); 502 503 _max_workers = MAX2(_max_workers, 1U); 504 _workers = new ShenandoahWorkerThreads("Shenandoah GC Threads", _max_workers); 505 if (_workers == nullptr) { 506 vm_exit_during_initialization("Failed necessary allocation."); 507 } else { 508 _workers->initialize_workers(); 509 } 510 511 if (ParallelGCThreads > 1) { 512 _safepoint_workers = new ShenandoahWorkerThreads("Safepoint Cleanup Thread", 513 ParallelGCThreads); 514 _safepoint_workers->initialize_workers(); 515 } 516 } 517 518 #ifdef _MSC_VER 519 #pragma warning( pop ) 520 #endif 521 522 class ShenandoahResetBitmapTask : public WorkerTask { 523 private: 524 ShenandoahRegionIterator _regions; 525 526 public: 527 ShenandoahResetBitmapTask() : 528 WorkerTask("Shenandoah Reset Bitmap") {} 529 530 void work(uint worker_id) { 531 ShenandoahHeapRegion* region = _regions.next(); 532 ShenandoahHeap* heap = ShenandoahHeap::heap(); 533 ShenandoahMarkingContext* const ctx = heap->marking_context(); 534 while (region != nullptr) { 535 if (heap->is_bitmap_slice_committed(region)) { 536 ctx->clear_bitmap(region); 537 } 538 region = _regions.next(); 539 } 540 } 541 }; 542 543 void ShenandoahHeap::reset_mark_bitmap() { 544 assert_gc_workers(_workers->active_workers()); 545 mark_incomplete_marking_context(); 546 547 ShenandoahResetBitmapTask task; 548 _workers->run_task(&task); 549 } 550 551 void ShenandoahHeap::print_on(outputStream* st) const { 552 st->print_cr("Shenandoah Heap"); 553 st->print_cr(" " SIZE_FORMAT "%s max, " SIZE_FORMAT "%s soft max, " SIZE_FORMAT "%s committed, " SIZE_FORMAT "%s used", 554 byte_size_in_proper_unit(max_capacity()), proper_unit_for_byte_size(max_capacity()), 555 byte_size_in_proper_unit(soft_max_capacity()), proper_unit_for_byte_size(soft_max_capacity()), 556 byte_size_in_proper_unit(committed()), proper_unit_for_byte_size(committed()), 557 byte_size_in_proper_unit(used()), proper_unit_for_byte_size(used())); 558 st->print_cr(" " SIZE_FORMAT " x " SIZE_FORMAT"%s regions", 559 num_regions(), 560 byte_size_in_proper_unit(ShenandoahHeapRegion::region_size_bytes()), 561 proper_unit_for_byte_size(ShenandoahHeapRegion::region_size_bytes())); 562 563 st->print("Status: "); 564 if (has_forwarded_objects()) st->print("has forwarded objects, "); 565 if (is_concurrent_mark_in_progress()) st->print("marking, "); 566 if (is_evacuation_in_progress()) st->print("evacuating, "); 567 if (is_update_refs_in_progress()) st->print("updating refs, "); 568 if (is_degenerated_gc_in_progress()) st->print("degenerated gc, "); 569 if (is_full_gc_in_progress()) st->print("full gc, "); 570 if (is_full_gc_move_in_progress()) st->print("full gc move, "); 571 if (is_concurrent_weak_root_in_progress()) st->print("concurrent weak roots, "); 572 if (is_concurrent_strong_root_in_progress() && 573 !is_concurrent_weak_root_in_progress()) st->print("concurrent strong roots, "); 574 575 if (cancelled_gc()) { 576 st->print("cancelled"); 577 } else { 578 st->print("not cancelled"); 579 } 580 st->cr(); 581 582 st->print_cr("Reserved region:"); 583 st->print_cr(" - [" PTR_FORMAT ", " PTR_FORMAT ") ", 584 p2i(reserved_region().start()), 585 p2i(reserved_region().end())); 586 587 ShenandoahCollectionSet* cset = collection_set(); 588 st->print_cr("Collection set:"); 589 if (cset != nullptr) { 590 st->print_cr(" - map (vanilla): " PTR_FORMAT, p2i(cset->map_address())); 591 st->print_cr(" - map (biased): " PTR_FORMAT, p2i(cset->biased_map_address())); 592 } else { 593 st->print_cr(" (null)"); 594 } 595 596 st->cr(); 597 MetaspaceUtils::print_on(st); 598 599 if (Verbose) { 600 print_heap_regions_on(st); 601 } 602 } 603 604 class ShenandoahInitWorkerGCLABClosure : public ThreadClosure { 605 public: 606 void do_thread(Thread* thread) { 607 assert(thread != nullptr, "Sanity"); 608 assert(thread->is_Worker_thread(), "Only worker thread expected"); 609 ShenandoahThreadLocalData::initialize_gclab(thread); 610 } 611 }; 612 613 void ShenandoahHeap::post_initialize() { 614 CollectedHeap::post_initialize(); 615 MutexLocker ml(Threads_lock); 616 617 ShenandoahInitWorkerGCLABClosure init_gclabs; 618 _workers->threads_do(&init_gclabs); 619 620 // gclab can not be initialized early during VM startup, as it can not determinate its max_size. 621 // Now, we will let WorkerThreads to initialize gclab when new worker is created. 622 _workers->set_initialize_gclab(); 623 if (_safepoint_workers != nullptr) { 624 _safepoint_workers->threads_do(&init_gclabs); 625 _safepoint_workers->set_initialize_gclab(); 626 } 627 628 _heuristics->initialize(); 629 630 JFR_ONLY(ShenandoahJFRSupport::register_jfr_type_serializers()); 631 } 632 633 size_t ShenandoahHeap::used() const { 634 return Atomic::load(&_used); 635 } 636 637 size_t ShenandoahHeap::committed() const { 638 return Atomic::load(&_committed); 639 } 640 641 void ShenandoahHeap::increase_committed(size_t bytes) { 642 shenandoah_assert_heaplocked_or_safepoint(); 643 _committed += bytes; 644 } 645 646 void ShenandoahHeap::decrease_committed(size_t bytes) { 647 shenandoah_assert_heaplocked_or_safepoint(); 648 _committed -= bytes; 649 } 650 651 void ShenandoahHeap::increase_used(size_t bytes) { 652 Atomic::add(&_used, bytes, memory_order_relaxed); 653 } 654 655 void ShenandoahHeap::set_used(size_t bytes) { 656 Atomic::store(&_used, bytes); 657 } 658 659 void ShenandoahHeap::decrease_used(size_t bytes) { 660 assert(used() >= bytes, "never decrease heap size by more than we've left"); 661 Atomic::sub(&_used, bytes, memory_order_relaxed); 662 } 663 664 void ShenandoahHeap::increase_allocated(size_t bytes) { 665 Atomic::add(&_bytes_allocated_since_gc_start, bytes, memory_order_relaxed); 666 } 667 668 void ShenandoahHeap::notify_mutator_alloc_words(size_t words, bool waste) { 669 size_t bytes = words * HeapWordSize; 670 if (!waste) { 671 increase_used(bytes); 672 } 673 increase_allocated(bytes); 674 if (ShenandoahPacing) { 675 control_thread()->pacing_notify_alloc(words); 676 if (waste) { 677 pacer()->claim_for_alloc(words, true); 678 } 679 } 680 } 681 682 size_t ShenandoahHeap::capacity() const { 683 return committed(); 684 } 685 686 size_t ShenandoahHeap::max_capacity() const { 687 return _num_regions * ShenandoahHeapRegion::region_size_bytes(); 688 } 689 690 size_t ShenandoahHeap::soft_max_capacity() const { 691 size_t v = Atomic::load(&_soft_max_size); 692 assert(min_capacity() <= v && v <= max_capacity(), 693 "Should be in bounds: " SIZE_FORMAT " <= " SIZE_FORMAT " <= " SIZE_FORMAT, 694 min_capacity(), v, max_capacity()); 695 return v; 696 } 697 698 void ShenandoahHeap::set_soft_max_capacity(size_t v) { 699 assert(min_capacity() <= v && v <= max_capacity(), 700 "Should be in bounds: " SIZE_FORMAT " <= " SIZE_FORMAT " <= " SIZE_FORMAT, 701 min_capacity(), v, max_capacity()); 702 Atomic::store(&_soft_max_size, v); 703 } 704 705 size_t ShenandoahHeap::min_capacity() const { 706 return _minimum_size; 707 } 708 709 size_t ShenandoahHeap::initial_capacity() const { 710 return _initial_size; 711 } 712 713 bool ShenandoahHeap::is_in(const void* p) const { 714 HeapWord* heap_base = (HeapWord*) base(); 715 HeapWord* last_region_end = heap_base + ShenandoahHeapRegion::region_size_words() * num_regions(); 716 return p >= heap_base && p < last_region_end; 717 } 718 719 void ShenandoahHeap::op_uncommit(double shrink_before, size_t shrink_until) { 720 assert (ShenandoahUncommit, "should be enabled"); 721 722 // Application allocates from the beginning of the heap, and GC allocates at 723 // the end of it. It is more efficient to uncommit from the end, so that applications 724 // could enjoy the near committed regions. GC allocations are much less frequent, 725 // and therefore can accept the committing costs. 726 727 size_t count = 0; 728 for (size_t i = num_regions(); i > 0; i--) { // care about size_t underflow 729 ShenandoahHeapRegion* r = get_region(i - 1); 730 if (r->is_empty_committed() && (r->empty_time() < shrink_before)) { 731 ShenandoahHeapLocker locker(lock()); 732 if (r->is_empty_committed()) { 733 if (committed() < shrink_until + ShenandoahHeapRegion::region_size_bytes()) { 734 break; 735 } 736 737 r->make_uncommitted(); 738 count++; 739 } 740 } 741 SpinPause(); // allow allocators to take the lock 742 } 743 744 if (count > 0) { 745 control_thread()->notify_heap_changed(); 746 } 747 } 748 749 HeapWord* ShenandoahHeap::allocate_from_gclab_slow(Thread* thread, size_t size) { 750 // New object should fit the GCLAB size 751 size_t min_size = MAX2(size, PLAB::min_size()); 752 753 // Figure out size of new GCLAB, looking back at heuristics. Expand aggressively. 754 size_t new_size = ShenandoahThreadLocalData::gclab_size(thread) * 2; 755 new_size = MIN2(new_size, PLAB::max_size()); 756 new_size = MAX2(new_size, PLAB::min_size()); 757 758 // Record new heuristic value even if we take any shortcut. This captures 759 // the case when moderately-sized objects always take a shortcut. At some point, 760 // heuristics should catch up with them. 761 ShenandoahThreadLocalData::set_gclab_size(thread, new_size); 762 763 if (new_size < size) { 764 // New size still does not fit the object. Fall back to shared allocation. 765 // This avoids retiring perfectly good GCLABs, when we encounter a large object. 766 return nullptr; 767 } 768 769 // Retire current GCLAB, and allocate a new one. 770 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread); 771 gclab->retire(); 772 773 size_t actual_size = 0; 774 HeapWord* gclab_buf = allocate_new_gclab(min_size, new_size, &actual_size); 775 if (gclab_buf == nullptr) { 776 return nullptr; 777 } 778 779 assert (size <= actual_size, "allocation should fit"); 780 781 if (ZeroTLAB) { 782 // ..and clear it. 783 Copy::zero_to_words(gclab_buf, actual_size); 784 } else { 785 // ...and zap just allocated object. 786 #ifdef ASSERT 787 // Skip mangling the space corresponding to the object header to 788 // ensure that the returned space is not considered parsable by 789 // any concurrent GC thread. 790 size_t hdr_size = oopDesc::header_size(); 791 Copy::fill_to_words(gclab_buf + hdr_size, actual_size - hdr_size, badHeapWordVal); 792 #endif // ASSERT 793 } 794 gclab->set_buf(gclab_buf, actual_size); 795 return gclab->allocate(size); 796 } 797 798 HeapWord* ShenandoahHeap::allocate_new_tlab(size_t min_size, 799 size_t requested_size, 800 size_t* actual_size) { 801 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_tlab(min_size, requested_size); 802 HeapWord* res = allocate_memory(req); 803 if (res != nullptr) { 804 *actual_size = req.actual_size(); 805 } else { 806 *actual_size = 0; 807 } 808 return res; 809 } 810 811 HeapWord* ShenandoahHeap::allocate_new_gclab(size_t min_size, 812 size_t word_size, 813 size_t* actual_size) { 814 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_gclab(min_size, word_size); 815 HeapWord* res = allocate_memory(req); 816 if (res != nullptr) { 817 *actual_size = req.actual_size(); 818 } else { 819 *actual_size = 0; 820 } 821 return res; 822 } 823 824 HeapWord* ShenandoahHeap::allocate_memory(ShenandoahAllocRequest& req) { 825 intptr_t pacer_epoch = 0; 826 bool in_new_region = false; 827 HeapWord* result = nullptr; 828 829 if (req.is_mutator_alloc()) { 830 if (ShenandoahPacing) { 831 pacer()->pace_for_alloc(req.size()); 832 pacer_epoch = pacer()->epoch(); 833 } 834 835 if (!ShenandoahAllocFailureALot || !should_inject_alloc_failure()) { 836 result = allocate_memory_under_lock(req, in_new_region); 837 } 838 839 // Allocation failed, block until control thread reacted, then retry allocation. 840 // 841 // It might happen that one of the threads requesting allocation would unblock 842 // way later after GC happened, only to fail the second allocation, because 843 // other threads have already depleted the free storage. In this case, a better 844 // strategy is to try again, as long as GC makes progress. 845 // 846 // Then, we need to make sure the allocation was retried after at least one 847 // Full GC, which means we want to try more than ShenandoahFullGCThreshold times. 848 849 size_t tries = 0; 850 851 while (result == nullptr && _progress_last_gc.is_set()) { 852 tries++; 853 control_thread()->handle_alloc_failure(req); 854 result = allocate_memory_under_lock(req, in_new_region); 855 } 856 857 while (result == nullptr && tries <= ShenandoahFullGCThreshold) { 858 tries++; 859 control_thread()->handle_alloc_failure(req); 860 result = allocate_memory_under_lock(req, in_new_region); 861 } 862 863 } else { 864 assert(req.is_gc_alloc(), "Can only accept GC allocs here"); 865 result = allocate_memory_under_lock(req, in_new_region); 866 // Do not call handle_alloc_failure() here, because we cannot block. 867 // The allocation failure would be handled by the LRB slowpath with handle_alloc_failure_evac(). 868 } 869 870 if (in_new_region) { 871 control_thread()->notify_heap_changed(); 872 } 873 874 if (result != nullptr) { 875 size_t requested = req.size(); 876 size_t actual = req.actual_size(); 877 878 assert (req.is_lab_alloc() || (requested == actual), 879 "Only LAB allocations are elastic: %s, requested = " SIZE_FORMAT ", actual = " SIZE_FORMAT, 880 ShenandoahAllocRequest::alloc_type_to_string(req.type()), requested, actual); 881 882 if (req.is_mutator_alloc()) { 883 notify_mutator_alloc_words(actual, false); 884 885 // If we requested more than we were granted, give the rest back to pacer. 886 // This only matters if we are in the same pacing epoch: do not try to unpace 887 // over the budget for the other phase. 888 if (ShenandoahPacing && (pacer_epoch > 0) && (requested > actual)) { 889 pacer()->unpace_for_alloc(pacer_epoch, requested - actual); 890 } 891 } else { 892 increase_used(actual*HeapWordSize); 893 } 894 } 895 896 return result; 897 } 898 899 HeapWord* ShenandoahHeap::allocate_memory_under_lock(ShenandoahAllocRequest& req, bool& in_new_region) { 900 ShenandoahHeapLocker locker(lock()); 901 return _free_set->allocate(req, in_new_region); 902 } 903 904 HeapWord* ShenandoahHeap::mem_allocate(size_t size, 905 bool* gc_overhead_limit_was_exceeded) { 906 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_shared(size); 907 return allocate_memory(req); 908 } 909 910 MetaWord* ShenandoahHeap::satisfy_failed_metadata_allocation(ClassLoaderData* loader_data, 911 size_t size, 912 Metaspace::MetadataType mdtype) { 913 MetaWord* result; 914 915 // Inform metaspace OOM to GC heuristics if class unloading is possible. 916 if (heuristics()->can_unload_classes()) { 917 ShenandoahHeuristics* h = heuristics(); 918 h->record_metaspace_oom(); 919 } 920 921 // Expand and retry allocation 922 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype); 923 if (result != nullptr) { 924 return result; 925 } 926 927 // Start full GC 928 collect(GCCause::_metadata_GC_clear_soft_refs); 929 930 // Retry allocation 931 result = loader_data->metaspace_non_null()->allocate(size, mdtype); 932 if (result != nullptr) { 933 return result; 934 } 935 936 // Expand and retry allocation 937 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype); 938 if (result != nullptr) { 939 return result; 940 } 941 942 // Out of memory 943 return nullptr; 944 } 945 946 class ShenandoahConcurrentEvacuateRegionObjectClosure : public ObjectClosure { 947 private: 948 ShenandoahHeap* const _heap; 949 Thread* const _thread; 950 public: 951 ShenandoahConcurrentEvacuateRegionObjectClosure(ShenandoahHeap* heap) : 952 _heap(heap), _thread(Thread::current()) {} 953 954 void do_object(oop p) { 955 shenandoah_assert_marked(nullptr, p); 956 if (!ShenandoahForwarding::is_forwarded(p)) { 957 _heap->evacuate_object(p, _thread); 958 } 959 } 960 }; 961 962 class ShenandoahEvacuationTask : public WorkerTask { 963 private: 964 ShenandoahHeap* const _sh; 965 ShenandoahCollectionSet* const _cs; 966 bool _concurrent; 967 public: 968 ShenandoahEvacuationTask(ShenandoahHeap* sh, 969 ShenandoahCollectionSet* cs, 970 bool concurrent) : 971 WorkerTask("Shenandoah Evacuation"), 972 _sh(sh), 973 _cs(cs), 974 _concurrent(concurrent) 975 {} 976 977 void work(uint worker_id) { 978 if (_concurrent) { 979 ShenandoahConcurrentWorkerSession worker_session(worker_id); 980 ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers); 981 ShenandoahEvacOOMScope oom_evac_scope; 982 do_work(); 983 } else { 984 ShenandoahParallelWorkerSession worker_session(worker_id); 985 ShenandoahEvacOOMScope oom_evac_scope; 986 do_work(); 987 } 988 } 989 990 private: 991 void do_work() { 992 ShenandoahConcurrentEvacuateRegionObjectClosure cl(_sh); 993 ShenandoahHeapRegion* r; 994 while ((r =_cs->claim_next()) != nullptr) { 995 assert(r->has_live(), "Region " SIZE_FORMAT " should have been reclaimed early", r->index()); 996 _sh->marked_object_iterate(r, &cl); 997 998 if (ShenandoahPacing) { 999 _sh->pacer()->report_evac(r->used() >> LogHeapWordSize); 1000 } 1001 1002 if (_sh->check_cancelled_gc_and_yield(_concurrent)) { 1003 break; 1004 } 1005 } 1006 } 1007 }; 1008 1009 void ShenandoahHeap::evacuate_collection_set(bool concurrent) { 1010 ShenandoahEvacuationTask task(this, _collection_set, concurrent); 1011 workers()->run_task(&task); 1012 } 1013 1014 void ShenandoahHeap::trash_cset_regions() { 1015 ShenandoahHeapLocker locker(lock()); 1016 1017 ShenandoahCollectionSet* set = collection_set(); 1018 ShenandoahHeapRegion* r; 1019 set->clear_current_index(); 1020 while ((r = set->next()) != nullptr) { 1021 r->make_trash(); 1022 } 1023 collection_set()->clear(); 1024 } 1025 1026 void ShenandoahHeap::print_heap_regions_on(outputStream* st) const { 1027 st->print_cr("Heap Regions:"); 1028 st->print_cr("EU=empty-uncommitted, EC=empty-committed, R=regular, H=humongous start, HC=humongous continuation, CS=collection set, T=trash, P=pinned"); 1029 st->print_cr("BTE=bottom/top/end, U=used, T=TLAB allocs, G=GCLAB allocs, S=shared allocs, L=live data"); 1030 st->print_cr("R=root, CP=critical pins, TAMS=top-at-mark-start, UWM=update watermark"); 1031 st->print_cr("SN=alloc sequence number"); 1032 1033 for (size_t i = 0; i < num_regions(); i++) { 1034 get_region(i)->print_on(st); 1035 } 1036 } 1037 1038 void ShenandoahHeap::trash_humongous_region_at(ShenandoahHeapRegion* start) { 1039 assert(start->is_humongous_start(), "reclaim regions starting with the first one"); 1040 1041 oop humongous_obj = cast_to_oop(start->bottom()); 1042 size_t size = humongous_obj->size(); 1043 size_t required_regions = ShenandoahHeapRegion::required_regions(size * HeapWordSize); 1044 size_t index = start->index() + required_regions - 1; 1045 1046 assert(!start->has_live(), "liveness must be zero"); 1047 1048 for(size_t i = 0; i < required_regions; i++) { 1049 // Reclaim from tail. Otherwise, assertion fails when printing region to trace log, 1050 // as it expects that every region belongs to a humongous region starting with a humongous start region. 1051 ShenandoahHeapRegion* region = get_region(index --); 1052 1053 assert(region->is_humongous(), "expect correct humongous start or continuation"); 1054 assert(!region->is_cset(), "Humongous region should not be in collection set"); 1055 1056 region->make_trash_immediate(); 1057 } 1058 } 1059 1060 class ShenandoahCheckCleanGCLABClosure : public ThreadClosure { 1061 public: 1062 ShenandoahCheckCleanGCLABClosure() {} 1063 void do_thread(Thread* thread) { 1064 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread); 1065 assert(gclab != nullptr, "GCLAB should be initialized for %s", thread->name()); 1066 assert(gclab->words_remaining() == 0, "GCLAB should not need retirement"); 1067 } 1068 }; 1069 1070 class ShenandoahRetireGCLABClosure : public ThreadClosure { 1071 private: 1072 bool const _resize; 1073 public: 1074 ShenandoahRetireGCLABClosure(bool resize) : _resize(resize) {} 1075 void do_thread(Thread* thread) { 1076 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread); 1077 assert(gclab != nullptr, "GCLAB should be initialized for %s", thread->name()); 1078 gclab->retire(); 1079 if (_resize && ShenandoahThreadLocalData::gclab_size(thread) > 0) { 1080 ShenandoahThreadLocalData::set_gclab_size(thread, 0); 1081 } 1082 } 1083 }; 1084 1085 void ShenandoahHeap::labs_make_parsable() { 1086 assert(UseTLAB, "Only call with UseTLAB"); 1087 1088 ShenandoahRetireGCLABClosure cl(false); 1089 1090 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) { 1091 ThreadLocalAllocBuffer& tlab = t->tlab(); 1092 tlab.make_parsable(); 1093 cl.do_thread(t); 1094 } 1095 1096 workers()->threads_do(&cl); 1097 } 1098 1099 void ShenandoahHeap::tlabs_retire(bool resize) { 1100 assert(UseTLAB, "Only call with UseTLAB"); 1101 assert(!resize || ResizeTLAB, "Only call for resize when ResizeTLAB is enabled"); 1102 1103 ThreadLocalAllocStats stats; 1104 1105 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) { 1106 ThreadLocalAllocBuffer& tlab = t->tlab(); 1107 tlab.retire(&stats); 1108 if (resize) { 1109 tlab.resize(); 1110 } 1111 } 1112 1113 stats.publish(); 1114 1115 #ifdef ASSERT 1116 ShenandoahCheckCleanGCLABClosure cl; 1117 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) { 1118 cl.do_thread(t); 1119 } 1120 workers()->threads_do(&cl); 1121 #endif 1122 } 1123 1124 void ShenandoahHeap::gclabs_retire(bool resize) { 1125 assert(UseTLAB, "Only call with UseTLAB"); 1126 assert(!resize || ResizeTLAB, "Only call for resize when ResizeTLAB is enabled"); 1127 1128 ShenandoahRetireGCLABClosure cl(resize); 1129 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) { 1130 cl.do_thread(t); 1131 } 1132 workers()->threads_do(&cl); 1133 1134 if (safepoint_workers() != nullptr) { 1135 safepoint_workers()->threads_do(&cl); 1136 } 1137 } 1138 1139 // Returns size in bytes 1140 size_t ShenandoahHeap::unsafe_max_tlab_alloc(Thread *thread) const { 1141 if (ShenandoahElasticTLAB) { 1142 // With Elastic TLABs, return the max allowed size, and let the allocation path 1143 // figure out the safe size for current allocation. 1144 return ShenandoahHeapRegion::max_tlab_size_bytes(); 1145 } else { 1146 return MIN2(_free_set->unsafe_peek_free(), ShenandoahHeapRegion::max_tlab_size_bytes()); 1147 } 1148 } 1149 1150 size_t ShenandoahHeap::max_tlab_size() const { 1151 // Returns size in words 1152 return ShenandoahHeapRegion::max_tlab_size_words(); 1153 } 1154 1155 void ShenandoahHeap::collect(GCCause::Cause cause) { 1156 control_thread()->request_gc(cause); 1157 } 1158 1159 void ShenandoahHeap::do_full_collection(bool clear_all_soft_refs) { 1160 //assert(false, "Shouldn't need to do full collections"); 1161 } 1162 1163 HeapWord* ShenandoahHeap::block_start(const void* addr) const { 1164 ShenandoahHeapRegion* r = heap_region_containing(addr); 1165 if (r != nullptr) { 1166 return r->block_start(addr); 1167 } 1168 return nullptr; 1169 } 1170 1171 bool ShenandoahHeap::block_is_obj(const HeapWord* addr) const { 1172 ShenandoahHeapRegion* r = heap_region_containing(addr); 1173 return r->block_is_obj(addr); 1174 } 1175 1176 bool ShenandoahHeap::print_location(outputStream* st, void* addr) const { 1177 return BlockLocationPrinter<ShenandoahHeap>::print_location(st, addr); 1178 } 1179 1180 void ShenandoahHeap::prepare_for_verify() { 1181 if (SafepointSynchronize::is_at_safepoint() && UseTLAB) { 1182 labs_make_parsable(); 1183 } 1184 } 1185 1186 void ShenandoahHeap::gc_threads_do(ThreadClosure* tcl) const { 1187 tcl->do_thread(_control_thread); 1188 workers()->threads_do(tcl); 1189 if (_safepoint_workers != nullptr) { 1190 _safepoint_workers->threads_do(tcl); 1191 } 1192 if (ShenandoahStringDedup::is_enabled()) { 1193 ShenandoahStringDedup::threads_do(tcl); 1194 } 1195 } 1196 1197 void ShenandoahHeap::print_tracing_info() const { 1198 LogTarget(Info, gc, stats) lt; 1199 if (lt.is_enabled()) { 1200 ResourceMark rm; 1201 LogStream ls(lt); 1202 1203 phase_timings()->print_global_on(&ls); 1204 1205 ls.cr(); 1206 ls.cr(); 1207 1208 shenandoah_policy()->print_gc_stats(&ls); 1209 1210 ls.cr(); 1211 ls.cr(); 1212 } 1213 } 1214 1215 void ShenandoahHeap::verify(VerifyOption vo) { 1216 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) { 1217 if (ShenandoahVerify) { 1218 verifier()->verify_generic(vo); 1219 } else { 1220 // TODO: Consider allocating verification bitmaps on demand, 1221 // and turn this on unconditionally. 1222 } 1223 } 1224 } 1225 size_t ShenandoahHeap::tlab_capacity(Thread *thr) const { 1226 return _free_set->capacity(); 1227 } 1228 1229 class ObjectIterateScanRootClosure : public BasicOopIterateClosure { 1230 private: 1231 MarkBitMap* _bitmap; 1232 ShenandoahScanObjectStack* _oop_stack; 1233 ShenandoahHeap* const _heap; 1234 ShenandoahMarkingContext* const _marking_context; 1235 1236 template <class T> 1237 void do_oop_work(T* p) { 1238 T o = RawAccess<>::oop_load(p); 1239 if (!CompressedOops::is_null(o)) { 1240 oop obj = CompressedOops::decode_not_null(o); 1241 if (_heap->is_concurrent_weak_root_in_progress() && !_marking_context->is_marked(obj)) { 1242 // There may be dead oops in weak roots in concurrent root phase, do not touch them. 1243 return; 1244 } 1245 obj = ShenandoahBarrierSet::barrier_set()->load_reference_barrier(obj); 1246 1247 assert(oopDesc::is_oop(obj), "must be a valid oop"); 1248 if (!_bitmap->is_marked(obj)) { 1249 _bitmap->mark(obj); 1250 _oop_stack->push(obj); 1251 } 1252 } 1253 } 1254 public: 1255 ObjectIterateScanRootClosure(MarkBitMap* bitmap, ShenandoahScanObjectStack* oop_stack) : 1256 _bitmap(bitmap), _oop_stack(oop_stack), _heap(ShenandoahHeap::heap()), 1257 _marking_context(_heap->marking_context()) {} 1258 void do_oop(oop* p) { do_oop_work(p); } 1259 void do_oop(narrowOop* p) { do_oop_work(p); } 1260 }; 1261 1262 /* 1263 * This is public API, used in preparation of object_iterate(). 1264 * Since we don't do linear scan of heap in object_iterate() (see comment below), we don't 1265 * need to make the heap parsable. For Shenandoah-internal linear heap scans that we can 1266 * control, we call SH::tlabs_retire, SH::gclabs_retire. 1267 */ 1268 void ShenandoahHeap::ensure_parsability(bool retire_tlabs) { 1269 // No-op. 1270 } 1271 1272 /* 1273 * Iterates objects in the heap. This is public API, used for, e.g., heap dumping. 1274 * 1275 * We cannot safely iterate objects by doing a linear scan at random points in time. Linear 1276 * scanning needs to deal with dead objects, which may have dead Klass* pointers (e.g. 1277 * calling oopDesc::size() would crash) or dangling reference fields (crashes) etc. Linear 1278 * scanning therefore depends on having a valid marking bitmap to support it. However, we only 1279 * have a valid marking bitmap after successful marking. In particular, we *don't* have a valid 1280 * marking bitmap during marking, after aborted marking or during/after cleanup (when we just 1281 * wiped the bitmap in preparation for next marking). 1282 * 1283 * For all those reasons, we implement object iteration as a single marking traversal, reporting 1284 * objects as we mark+traverse through the heap, starting from GC roots. JVMTI IterateThroughHeap 1285 * is allowed to report dead objects, but is not required to do so. 1286 */ 1287 void ShenandoahHeap::object_iterate(ObjectClosure* cl) { 1288 // Reset bitmap 1289 if (!prepare_aux_bitmap_for_iteration()) 1290 return; 1291 1292 ShenandoahScanObjectStack oop_stack; 1293 ObjectIterateScanRootClosure oops(&_aux_bit_map, &oop_stack); 1294 // Seed the stack with root scan 1295 scan_roots_for_iteration(&oop_stack, &oops); 1296 1297 // Work through the oop stack to traverse heap 1298 while (! oop_stack.is_empty()) { 1299 oop obj = oop_stack.pop(); 1300 assert(oopDesc::is_oop(obj), "must be a valid oop"); 1301 shenandoah_assert_not_in_cset_except(NULL, obj, cancelled_gc()); 1302 cl->do_object(obj); 1303 obj->oop_iterate(&oops); 1304 } 1305 1306 assert(oop_stack.is_empty(), "should be empty"); 1307 // Reclaim bitmap 1308 reclaim_aux_bitmap_for_iteration(); 1309 } 1310 1311 bool ShenandoahHeap::prepare_aux_bitmap_for_iteration() { 1312 assert(SafepointSynchronize::is_at_safepoint(), "safe iteration is only available during safepoints"); 1313 1314 if (!_aux_bitmap_region_special && !os::commit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size(), false)) { 1315 log_warning(gc)("Could not commit native memory for auxiliary marking bitmap for heap iteration"); 1316 return false; 1317 } 1318 // Reset bitmap 1319 _aux_bit_map.clear(); 1320 return true; 1321 } 1322 1323 void ShenandoahHeap::scan_roots_for_iteration(ShenandoahScanObjectStack* oop_stack, ObjectIterateScanRootClosure* oops) { 1324 // Process GC roots according to current GC cycle 1325 // This populates the work stack with initial objects 1326 // It is important to relinquish the associated locks before diving 1327 // into heap dumper 1328 uint n_workers = safepoint_workers() != nullptr ? safepoint_workers()->active_workers() : 1; 1329 ShenandoahHeapIterationRootScanner rp(n_workers); 1330 rp.roots_do(oops); 1331 } 1332 1333 void ShenandoahHeap::reclaim_aux_bitmap_for_iteration() { 1334 if (!_aux_bitmap_region_special && !os::uncommit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size())) { 1335 log_warning(gc)("Could not uncommit native memory for auxiliary marking bitmap for heap iteration"); 1336 } 1337 } 1338 1339 // Closure for parallelly iterate objects 1340 class ShenandoahObjectIterateParScanClosure : public BasicOopIterateClosure { 1341 private: 1342 MarkBitMap* _bitmap; 1343 ShenandoahObjToScanQueue* _queue; 1344 ShenandoahHeap* const _heap; 1345 ShenandoahMarkingContext* const _marking_context; 1346 1347 template <class T> 1348 void do_oop_work(T* p) { 1349 T o = RawAccess<>::oop_load(p); 1350 if (!CompressedOops::is_null(o)) { 1351 oop obj = CompressedOops::decode_not_null(o); 1352 if (_heap->is_concurrent_weak_root_in_progress() && !_marking_context->is_marked(obj)) { 1353 // There may be dead oops in weak roots in concurrent root phase, do not touch them. 1354 return; 1355 } 1356 obj = ShenandoahBarrierSet::barrier_set()->load_reference_barrier(obj); 1357 1358 assert(oopDesc::is_oop(obj), "Must be a valid oop"); 1359 if (_bitmap->par_mark(obj)) { 1360 _queue->push(ShenandoahMarkTask(obj)); 1361 } 1362 } 1363 } 1364 public: 1365 ShenandoahObjectIterateParScanClosure(MarkBitMap* bitmap, ShenandoahObjToScanQueue* q) : 1366 _bitmap(bitmap), _queue(q), _heap(ShenandoahHeap::heap()), 1367 _marking_context(_heap->marking_context()) {} 1368 void do_oop(oop* p) { do_oop_work(p); } 1369 void do_oop(narrowOop* p) { do_oop_work(p); } 1370 }; 1371 1372 // Object iterator for parallel heap iteraion. 1373 // The root scanning phase happenes in construction as a preparation of 1374 // parallel marking queues. 1375 // Every worker processes it's own marking queue. work-stealing is used 1376 // to balance workload. 1377 class ShenandoahParallelObjectIterator : public ParallelObjectIteratorImpl { 1378 private: 1379 uint _num_workers; 1380 bool _init_ready; 1381 MarkBitMap* _aux_bit_map; 1382 ShenandoahHeap* _heap; 1383 ShenandoahScanObjectStack _roots_stack; // global roots stack 1384 ShenandoahObjToScanQueueSet* _task_queues; 1385 public: 1386 ShenandoahParallelObjectIterator(uint num_workers, MarkBitMap* bitmap) : 1387 _num_workers(num_workers), 1388 _init_ready(false), 1389 _aux_bit_map(bitmap), 1390 _heap(ShenandoahHeap::heap()) { 1391 // Initialize bitmap 1392 _init_ready = _heap->prepare_aux_bitmap_for_iteration(); 1393 if (!_init_ready) { 1394 return; 1395 } 1396 1397 ObjectIterateScanRootClosure oops(_aux_bit_map, &_roots_stack); 1398 _heap->scan_roots_for_iteration(&_roots_stack, &oops); 1399 1400 _init_ready = prepare_worker_queues(); 1401 } 1402 1403 ~ShenandoahParallelObjectIterator() { 1404 // Reclaim bitmap 1405 _heap->reclaim_aux_bitmap_for_iteration(); 1406 // Reclaim queue for workers 1407 if (_task_queues!= nullptr) { 1408 for (uint i = 0; i < _num_workers; ++i) { 1409 ShenandoahObjToScanQueue* q = _task_queues->queue(i); 1410 if (q != nullptr) { 1411 delete q; 1412 _task_queues->register_queue(i, nullptr); 1413 } 1414 } 1415 delete _task_queues; 1416 _task_queues = nullptr; 1417 } 1418 } 1419 1420 virtual void object_iterate(ObjectClosure* cl, uint worker_id) { 1421 if (_init_ready) { 1422 object_iterate_parallel(cl, worker_id, _task_queues); 1423 } 1424 } 1425 1426 private: 1427 // Divide global root_stack into worker queues 1428 bool prepare_worker_queues() { 1429 _task_queues = new ShenandoahObjToScanQueueSet((int) _num_workers); 1430 // Initialize queues for every workers 1431 for (uint i = 0; i < _num_workers; ++i) { 1432 ShenandoahObjToScanQueue* task_queue = new ShenandoahObjToScanQueue(); 1433 _task_queues->register_queue(i, task_queue); 1434 } 1435 // Divide roots among the workers. Assume that object referencing distribution 1436 // is related with root kind, use round-robin to make every worker have same chance 1437 // to process every kind of roots 1438 size_t roots_num = _roots_stack.size(); 1439 if (roots_num == 0) { 1440 // No work to do 1441 return false; 1442 } 1443 1444 for (uint j = 0; j < roots_num; j++) { 1445 uint stack_id = j % _num_workers; 1446 oop obj = _roots_stack.pop(); 1447 _task_queues->queue(stack_id)->push(ShenandoahMarkTask(obj)); 1448 } 1449 return true; 1450 } 1451 1452 void object_iterate_parallel(ObjectClosure* cl, 1453 uint worker_id, 1454 ShenandoahObjToScanQueueSet* queue_set) { 1455 assert(SafepointSynchronize::is_at_safepoint(), "safe iteration is only available during safepoints"); 1456 assert(queue_set != nullptr, "task queue must not be null"); 1457 1458 ShenandoahObjToScanQueue* q = queue_set->queue(worker_id); 1459 assert(q != nullptr, "object iterate queue must not be null"); 1460 1461 ShenandoahMarkTask t; 1462 ShenandoahObjectIterateParScanClosure oops(_aux_bit_map, q); 1463 1464 // Work through the queue to traverse heap. 1465 // Steal when there is no task in queue. 1466 while (q->pop(t) || queue_set->steal(worker_id, t)) { 1467 oop obj = t.obj(); 1468 assert(oopDesc::is_oop(obj), "must be a valid oop"); 1469 cl->do_object(obj); 1470 obj->oop_iterate(&oops); 1471 } 1472 assert(q->is_empty(), "should be empty"); 1473 } 1474 }; 1475 1476 ParallelObjectIteratorImpl* ShenandoahHeap::parallel_object_iterator(uint workers) { 1477 return new ShenandoahParallelObjectIterator(workers, &_aux_bit_map); 1478 } 1479 1480 // Keep alive an object that was loaded with AS_NO_KEEPALIVE. 1481 void ShenandoahHeap::keep_alive(oop obj) { 1482 if (is_concurrent_mark_in_progress() && (obj != nullptr)) { 1483 ShenandoahBarrierSet::barrier_set()->enqueue(obj); 1484 } 1485 } 1486 1487 void ShenandoahHeap::heap_region_iterate(ShenandoahHeapRegionClosure* blk) const { 1488 for (size_t i = 0; i < num_regions(); i++) { 1489 ShenandoahHeapRegion* current = get_region(i); 1490 blk->heap_region_do(current); 1491 } 1492 } 1493 1494 class ShenandoahParallelHeapRegionTask : public WorkerTask { 1495 private: 1496 ShenandoahHeap* const _heap; 1497 ShenandoahHeapRegionClosure* const _blk; 1498 1499 shenandoah_padding(0); 1500 volatile size_t _index; 1501 shenandoah_padding(1); 1502 1503 public: 1504 ShenandoahParallelHeapRegionTask(ShenandoahHeapRegionClosure* blk) : 1505 WorkerTask("Shenandoah Parallel Region Operation"), 1506 _heap(ShenandoahHeap::heap()), _blk(blk), _index(0) {} 1507 1508 void work(uint worker_id) { 1509 ShenandoahParallelWorkerSession worker_session(worker_id); 1510 size_t stride = ShenandoahParallelRegionStride; 1511 1512 size_t max = _heap->num_regions(); 1513 while (Atomic::load(&_index) < max) { 1514 size_t cur = Atomic::fetch_and_add(&_index, stride, memory_order_relaxed); 1515 size_t start = cur; 1516 size_t end = MIN2(cur + stride, max); 1517 if (start >= max) break; 1518 1519 for (size_t i = cur; i < end; i++) { 1520 ShenandoahHeapRegion* current = _heap->get_region(i); 1521 _blk->heap_region_do(current); 1522 } 1523 } 1524 } 1525 }; 1526 1527 void ShenandoahHeap::parallel_heap_region_iterate(ShenandoahHeapRegionClosure* blk) const { 1528 assert(blk->is_thread_safe(), "Only thread-safe closures here"); 1529 if (num_regions() > ShenandoahParallelRegionStride) { 1530 ShenandoahParallelHeapRegionTask task(blk); 1531 workers()->run_task(&task); 1532 } else { 1533 heap_region_iterate(blk); 1534 } 1535 } 1536 1537 class ShenandoahInitMarkUpdateRegionStateClosure : public ShenandoahHeapRegionClosure { 1538 private: 1539 ShenandoahMarkingContext* const _ctx; 1540 public: 1541 ShenandoahInitMarkUpdateRegionStateClosure() : _ctx(ShenandoahHeap::heap()->marking_context()) {} 1542 1543 void heap_region_do(ShenandoahHeapRegion* r) { 1544 assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->index()); 1545 if (r->is_active()) { 1546 // Check if region needs updating its TAMS. We have updated it already during concurrent 1547 // reset, so it is very likely we don't need to do another write here. 1548 if (_ctx->top_at_mark_start(r) != r->top()) { 1549 _ctx->capture_top_at_mark_start(r); 1550 } 1551 } else { 1552 assert(_ctx->top_at_mark_start(r) == r->top(), 1553 "Region " SIZE_FORMAT " should already have correct TAMS", r->index()); 1554 } 1555 } 1556 1557 bool is_thread_safe() { return true; } 1558 }; 1559 1560 class ShenandoahRendezvousClosure : public HandshakeClosure { 1561 public: 1562 inline ShenandoahRendezvousClosure() : HandshakeClosure("ShenandoahRendezvous") {} 1563 inline void do_thread(Thread* thread) {} 1564 }; 1565 1566 void ShenandoahHeap::rendezvous_threads() { 1567 ShenandoahRendezvousClosure cl; 1568 Handshake::execute(&cl); 1569 } 1570 1571 void ShenandoahHeap::recycle_trash() { 1572 free_set()->recycle_trash(); 1573 } 1574 1575 class ShenandoahResetUpdateRegionStateClosure : public ShenandoahHeapRegionClosure { 1576 private: 1577 ShenandoahMarkingContext* const _ctx; 1578 public: 1579 ShenandoahResetUpdateRegionStateClosure() : _ctx(ShenandoahHeap::heap()->marking_context()) {} 1580 1581 void heap_region_do(ShenandoahHeapRegion* r) { 1582 if (r->is_active()) { 1583 // Reset live data and set TAMS optimistically. We would recheck these under the pause 1584 // anyway to capture any updates that happened since now. 1585 r->clear_live_data(); 1586 _ctx->capture_top_at_mark_start(r); 1587 } 1588 } 1589 1590 bool is_thread_safe() { return true; } 1591 }; 1592 1593 void ShenandoahHeap::prepare_gc() { 1594 reset_mark_bitmap(); 1595 1596 ShenandoahResetUpdateRegionStateClosure cl; 1597 parallel_heap_region_iterate(&cl); 1598 } 1599 1600 class ShenandoahFinalMarkUpdateRegionStateClosure : public ShenandoahHeapRegionClosure { 1601 private: 1602 ShenandoahMarkingContext* const _ctx; 1603 ShenandoahHeapLock* const _lock; 1604 1605 public: 1606 ShenandoahFinalMarkUpdateRegionStateClosure() : 1607 _ctx(ShenandoahHeap::heap()->complete_marking_context()), _lock(ShenandoahHeap::heap()->lock()) {} 1608 1609 void heap_region_do(ShenandoahHeapRegion* r) { 1610 if (r->is_active()) { 1611 // All allocations past TAMS are implicitly live, adjust the region data. 1612 // Bitmaps/TAMS are swapped at this point, so we need to poll complete bitmap. 1613 HeapWord *tams = _ctx->top_at_mark_start(r); 1614 HeapWord *top = r->top(); 1615 if (top > tams) { 1616 r->increase_live_data_alloc_words(pointer_delta(top, tams)); 1617 } 1618 1619 // We are about to select the collection set, make sure it knows about 1620 // current pinning status. Also, this allows trashing more regions that 1621 // now have their pinning status dropped. 1622 if (r->is_pinned()) { 1623 if (r->pin_count() == 0) { 1624 ShenandoahHeapLocker locker(_lock); 1625 r->make_unpinned(); 1626 } 1627 } else { 1628 if (r->pin_count() > 0) { 1629 ShenandoahHeapLocker locker(_lock); 1630 r->make_pinned(); 1631 } 1632 } 1633 1634 // Remember limit for updating refs. It's guaranteed that we get no 1635 // from-space-refs written from here on. 1636 r->set_update_watermark_at_safepoint(r->top()); 1637 } else { 1638 assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->index()); 1639 assert(_ctx->top_at_mark_start(r) == r->top(), 1640 "Region " SIZE_FORMAT " should have correct TAMS", r->index()); 1641 } 1642 } 1643 1644 bool is_thread_safe() { return true; } 1645 }; 1646 1647 void ShenandoahHeap::prepare_regions_and_collection_set(bool concurrent) { 1648 assert(!is_full_gc_in_progress(), "Only for concurrent and degenerated GC"); 1649 { 1650 ShenandoahGCPhase phase(concurrent ? ShenandoahPhaseTimings::final_update_region_states : 1651 ShenandoahPhaseTimings::degen_gc_final_update_region_states); 1652 ShenandoahFinalMarkUpdateRegionStateClosure cl; 1653 parallel_heap_region_iterate(&cl); 1654 1655 assert_pinned_region_status(); 1656 } 1657 1658 { 1659 ShenandoahGCPhase phase(concurrent ? ShenandoahPhaseTimings::choose_cset : 1660 ShenandoahPhaseTimings::degen_gc_choose_cset); 1661 ShenandoahHeapLocker locker(lock()); 1662 _collection_set->clear(); 1663 heuristics()->choose_collection_set(_collection_set); 1664 } 1665 1666 { 1667 ShenandoahGCPhase phase(concurrent ? ShenandoahPhaseTimings::final_rebuild_freeset : 1668 ShenandoahPhaseTimings::degen_gc_final_rebuild_freeset); 1669 ShenandoahHeapLocker locker(lock()); 1670 _free_set->rebuild(); 1671 } 1672 } 1673 1674 void ShenandoahHeap::do_class_unloading() { 1675 _unloader.unload(); 1676 } 1677 1678 void ShenandoahHeap::stw_weak_refs(bool full_gc) { 1679 // Weak refs processing 1680 ShenandoahPhaseTimings::Phase phase = full_gc ? ShenandoahPhaseTimings::full_gc_weakrefs 1681 : ShenandoahPhaseTimings::degen_gc_weakrefs; 1682 ShenandoahTimingsTracker t(phase); 1683 ShenandoahGCWorkerPhase worker_phase(phase); 1684 ref_processor()->process_references(phase, workers(), false /* concurrent */); 1685 } 1686 1687 void ShenandoahHeap::prepare_update_heap_references(bool concurrent) { 1688 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint"); 1689 1690 // Evacuation is over, no GCLABs are needed anymore. GCLABs are under URWM, so we need to 1691 // make them parsable for update code to work correctly. Plus, we can compute new sizes 1692 // for future GCLABs here. 1693 if (UseTLAB) { 1694 ShenandoahGCPhase phase(concurrent ? 1695 ShenandoahPhaseTimings::init_update_refs_manage_gclabs : 1696 ShenandoahPhaseTimings::degen_gc_init_update_refs_manage_gclabs); 1697 gclabs_retire(ResizeTLAB); 1698 } 1699 1700 _update_refs_iterator.reset(); 1701 } 1702 1703 void ShenandoahHeap::set_gc_state_all_threads(char state) { 1704 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) { 1705 ShenandoahThreadLocalData::set_gc_state(t, state); 1706 } 1707 } 1708 1709 void ShenandoahHeap::set_gc_state_mask(uint mask, bool value) { 1710 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should really be Shenandoah safepoint"); 1711 _gc_state.set_cond(mask, value); 1712 set_gc_state_all_threads(_gc_state.raw_value()); 1713 } 1714 1715 void ShenandoahHeap::set_concurrent_mark_in_progress(bool in_progress) { 1716 assert(!has_forwarded_objects(), "Not expected before/after mark phase"); 1717 set_gc_state_mask(MARKING, in_progress); 1718 ShenandoahBarrierSet::satb_mark_queue_set().set_active_all_threads(in_progress, !in_progress); 1719 } 1720 1721 void ShenandoahHeap::set_evacuation_in_progress(bool in_progress) { 1722 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Only call this at safepoint"); 1723 set_gc_state_mask(EVACUATION, in_progress); 1724 } 1725 1726 void ShenandoahHeap::set_concurrent_strong_root_in_progress(bool in_progress) { 1727 if (in_progress) { 1728 _concurrent_strong_root_in_progress.set(); 1729 } else { 1730 _concurrent_strong_root_in_progress.unset(); 1731 } 1732 } 1733 1734 void ShenandoahHeap::set_concurrent_weak_root_in_progress(bool cond) { 1735 set_gc_state_mask(WEAK_ROOTS, cond); 1736 } 1737 1738 GCTracer* ShenandoahHeap::tracer() { 1739 return shenandoah_policy()->tracer(); 1740 } 1741 1742 size_t ShenandoahHeap::tlab_used(Thread* thread) const { 1743 return _free_set->used(); 1744 } 1745 1746 bool ShenandoahHeap::try_cancel_gc() { 1747 while (true) { 1748 jbyte prev = _cancelled_gc.cmpxchg(CANCELLED, CANCELLABLE); 1749 if (prev == CANCELLABLE) return true; 1750 else if (prev == CANCELLED) return false; 1751 assert(ShenandoahSuspendibleWorkers, "should not get here when not using suspendible workers"); 1752 assert(prev == NOT_CANCELLED, "must be NOT_CANCELLED"); 1753 Thread* thread = Thread::current(); 1754 if (thread->is_Java_thread()) { 1755 // We need to provide a safepoint here, otherwise we might 1756 // spin forever if a SP is pending. 1757 ThreadBlockInVM sp(JavaThread::cast(thread)); 1758 SpinPause(); 1759 } 1760 } 1761 } 1762 1763 void ShenandoahHeap::cancel_gc(GCCause::Cause cause) { 1764 if (try_cancel_gc()) { 1765 FormatBuffer<> msg("Cancelling GC: %s", GCCause::to_string(cause)); 1766 log_info(gc)("%s", msg.buffer()); 1767 Events::log(Thread::current(), "%s", msg.buffer()); 1768 } 1769 } 1770 1771 uint ShenandoahHeap::max_workers() { 1772 return _max_workers; 1773 } 1774 1775 void ShenandoahHeap::stop() { 1776 // The shutdown sequence should be able to terminate when GC is running. 1777 1778 // Step 0. Notify policy to disable event recording. 1779 _shenandoah_policy->record_shutdown(); 1780 1781 // Step 1. Notify control thread that we are in shutdown. 1782 // Note that we cannot do that with stop(), because stop() is blocking and waits for the actual shutdown. 1783 // Doing stop() here would wait for the normal GC cycle to complete, never falling through to cancel below. 1784 control_thread()->prepare_for_graceful_shutdown(); 1785 1786 // Step 2. Notify GC workers that we are cancelling GC. 1787 cancel_gc(GCCause::_shenandoah_stop_vm); 1788 1789 // Step 3. Wait until GC worker exits normally. 1790 control_thread()->stop(); 1791 } 1792 1793 void ShenandoahHeap::stw_unload_classes(bool full_gc) { 1794 if (!unload_classes()) return; 1795 // Unload classes and purge SystemDictionary. 1796 { 1797 ShenandoahPhaseTimings::Phase phase = full_gc ? 1798 ShenandoahPhaseTimings::full_gc_purge_class_unload : 1799 ShenandoahPhaseTimings::degen_gc_purge_class_unload; 1800 ShenandoahIsAliveSelector is_alive; 1801 CodeCache::UnloadingScope scope(is_alive.is_alive_closure()); 1802 ShenandoahGCPhase gc_phase(phase); 1803 ShenandoahGCWorkerPhase worker_phase(phase); 1804 bool purged_class = SystemDictionary::do_unloading(gc_timer()); 1805 1806 uint num_workers = _workers->active_workers(); 1807 ShenandoahClassUnloadingTask unlink_task(phase, num_workers, purged_class); 1808 _workers->run_task(&unlink_task); 1809 } 1810 1811 { 1812 ShenandoahGCPhase phase(full_gc ? 1813 ShenandoahPhaseTimings::full_gc_purge_cldg : 1814 ShenandoahPhaseTimings::degen_gc_purge_cldg); 1815 ClassLoaderDataGraph::purge(/*at_safepoint*/true); 1816 } 1817 // Resize and verify metaspace 1818 MetaspaceGC::compute_new_size(); 1819 DEBUG_ONLY(MetaspaceUtils::verify();) 1820 } 1821 1822 // Weak roots are either pre-evacuated (final mark) or updated (final updaterefs), 1823 // so they should not have forwarded oops. 1824 // However, we do need to "null" dead oops in the roots, if can not be done 1825 // in concurrent cycles. 1826 void ShenandoahHeap::stw_process_weak_roots(bool full_gc) { 1827 uint num_workers = _workers->active_workers(); 1828 ShenandoahPhaseTimings::Phase timing_phase = full_gc ? 1829 ShenandoahPhaseTimings::full_gc_purge_weak_par : 1830 ShenandoahPhaseTimings::degen_gc_purge_weak_par; 1831 ShenandoahGCPhase phase(timing_phase); 1832 ShenandoahGCWorkerPhase worker_phase(timing_phase); 1833 // Cleanup weak roots 1834 if (has_forwarded_objects()) { 1835 ShenandoahForwardedIsAliveClosure is_alive; 1836 ShenandoahUpdateRefsClosure keep_alive; 1837 ShenandoahParallelWeakRootsCleaningTask<ShenandoahForwardedIsAliveClosure, ShenandoahUpdateRefsClosure> 1838 cleaning_task(timing_phase, &is_alive, &keep_alive, num_workers); 1839 _workers->run_task(&cleaning_task); 1840 } else { 1841 ShenandoahIsAliveClosure is_alive; 1842 #ifdef ASSERT 1843 ShenandoahAssertNotForwardedClosure verify_cl; 1844 ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, ShenandoahAssertNotForwardedClosure> 1845 cleaning_task(timing_phase, &is_alive, &verify_cl, num_workers); 1846 #else 1847 ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, DoNothingClosure> 1848 cleaning_task(timing_phase, &is_alive, &do_nothing_cl, num_workers); 1849 #endif 1850 _workers->run_task(&cleaning_task); 1851 } 1852 } 1853 1854 void ShenandoahHeap::parallel_cleaning(bool full_gc) { 1855 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint"); 1856 assert(is_stw_gc_in_progress(), "Only for Degenerated and Full GC"); 1857 ShenandoahGCPhase phase(full_gc ? 1858 ShenandoahPhaseTimings::full_gc_purge : 1859 ShenandoahPhaseTimings::degen_gc_purge); 1860 stw_weak_refs(full_gc); 1861 stw_process_weak_roots(full_gc); 1862 stw_unload_classes(full_gc); 1863 } 1864 1865 void ShenandoahHeap::set_has_forwarded_objects(bool cond) { 1866 set_gc_state_mask(HAS_FORWARDED, cond); 1867 } 1868 1869 void ShenandoahHeap::set_unload_classes(bool uc) { 1870 _unload_classes.set_cond(uc); 1871 } 1872 1873 bool ShenandoahHeap::unload_classes() const { 1874 return _unload_classes.is_set(); 1875 } 1876 1877 address ShenandoahHeap::in_cset_fast_test_addr() { 1878 ShenandoahHeap* heap = ShenandoahHeap::heap(); 1879 assert(heap->collection_set() != nullptr, "Sanity"); 1880 return (address) heap->collection_set()->biased_map_address(); 1881 } 1882 1883 address ShenandoahHeap::cancelled_gc_addr() { 1884 return (address) ShenandoahHeap::heap()->_cancelled_gc.addr_of(); 1885 } 1886 1887 address ShenandoahHeap::gc_state_addr() { 1888 return (address) ShenandoahHeap::heap()->_gc_state.addr_of(); 1889 } 1890 1891 size_t ShenandoahHeap::bytes_allocated_since_gc_start() { 1892 return Atomic::load(&_bytes_allocated_since_gc_start); 1893 } 1894 1895 void ShenandoahHeap::reset_bytes_allocated_since_gc_start() { 1896 Atomic::store(&_bytes_allocated_since_gc_start, (size_t)0); 1897 } 1898 1899 void ShenandoahHeap::set_degenerated_gc_in_progress(bool in_progress) { 1900 _degenerated_gc_in_progress.set_cond(in_progress); 1901 } 1902 1903 void ShenandoahHeap::set_full_gc_in_progress(bool in_progress) { 1904 _full_gc_in_progress.set_cond(in_progress); 1905 } 1906 1907 void ShenandoahHeap::set_full_gc_move_in_progress(bool in_progress) { 1908 assert (is_full_gc_in_progress(), "should be"); 1909 _full_gc_move_in_progress.set_cond(in_progress); 1910 } 1911 1912 void ShenandoahHeap::set_update_refs_in_progress(bool in_progress) { 1913 set_gc_state_mask(UPDATEREFS, in_progress); 1914 } 1915 1916 void ShenandoahHeap::register_nmethod(nmethod* nm) { 1917 ShenandoahCodeRoots::register_nmethod(nm); 1918 } 1919 1920 void ShenandoahHeap::unregister_nmethod(nmethod* nm) { 1921 ShenandoahCodeRoots::unregister_nmethod(nm); 1922 } 1923 1924 void ShenandoahHeap::pin_object(JavaThread* thr, oop o) { 1925 heap_region_containing(o)->record_pin(); 1926 } 1927 1928 void ShenandoahHeap::unpin_object(JavaThread* thr, oop o) { 1929 ShenandoahHeapRegion* r = heap_region_containing(o); 1930 assert(r != nullptr, "Sanity"); 1931 assert(r->pin_count() > 0, "Region " SIZE_FORMAT " should have non-zero pins", r->index()); 1932 r->record_unpin(); 1933 } 1934 1935 void ShenandoahHeap::sync_pinned_region_status() { 1936 ShenandoahHeapLocker locker(lock()); 1937 1938 for (size_t i = 0; i < num_regions(); i++) { 1939 ShenandoahHeapRegion *r = get_region(i); 1940 if (r->is_active()) { 1941 if (r->is_pinned()) { 1942 if (r->pin_count() == 0) { 1943 r->make_unpinned(); 1944 } 1945 } else { 1946 if (r->pin_count() > 0) { 1947 r->make_pinned(); 1948 } 1949 } 1950 } 1951 } 1952 1953 assert_pinned_region_status(); 1954 } 1955 1956 #ifdef ASSERT 1957 void ShenandoahHeap::assert_pinned_region_status() { 1958 for (size_t i = 0; i < num_regions(); i++) { 1959 ShenandoahHeapRegion* r = get_region(i); 1960 assert((r->is_pinned() && r->pin_count() > 0) || (!r->is_pinned() && r->pin_count() == 0), 1961 "Region " SIZE_FORMAT " pinning status is inconsistent", i); 1962 } 1963 } 1964 #endif 1965 1966 ConcurrentGCTimer* ShenandoahHeap::gc_timer() const { 1967 return _gc_timer; 1968 } 1969 1970 void ShenandoahHeap::prepare_concurrent_roots() { 1971 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint"); 1972 assert(!is_stw_gc_in_progress(), "Only concurrent GC"); 1973 set_concurrent_strong_root_in_progress(!collection_set()->is_empty()); 1974 set_concurrent_weak_root_in_progress(true); 1975 if (unload_classes()) { 1976 _unloader.prepare(); 1977 } 1978 } 1979 1980 void ShenandoahHeap::finish_concurrent_roots() { 1981 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint"); 1982 assert(!is_stw_gc_in_progress(), "Only concurrent GC"); 1983 if (unload_classes()) { 1984 _unloader.finish(); 1985 } 1986 } 1987 1988 #ifdef ASSERT 1989 void ShenandoahHeap::assert_gc_workers(uint nworkers) { 1990 assert(nworkers > 0 && nworkers <= max_workers(), "Sanity"); 1991 1992 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) { 1993 if (UseDynamicNumberOfGCThreads) { 1994 assert(nworkers <= ParallelGCThreads, "Cannot use more than it has"); 1995 } else { 1996 // Use ParallelGCThreads inside safepoints 1997 assert(nworkers == ParallelGCThreads, "Use ParallelGCThreads within safepoints"); 1998 } 1999 } else { 2000 if (UseDynamicNumberOfGCThreads) { 2001 assert(nworkers <= ConcGCThreads, "Cannot use more than it has"); 2002 } else { 2003 // Use ConcGCThreads outside safepoints 2004 assert(nworkers == ConcGCThreads, "Use ConcGCThreads outside safepoints"); 2005 } 2006 } 2007 } 2008 #endif 2009 2010 ShenandoahVerifier* ShenandoahHeap::verifier() { 2011 guarantee(ShenandoahVerify, "Should be enabled"); 2012 assert (_verifier != nullptr, "sanity"); 2013 return _verifier; 2014 } 2015 2016 template<bool CONCURRENT> 2017 class ShenandoahUpdateHeapRefsTask : public WorkerTask { 2018 private: 2019 ShenandoahHeap* _heap; 2020 ShenandoahRegionIterator* _regions; 2021 public: 2022 ShenandoahUpdateHeapRefsTask(ShenandoahRegionIterator* regions) : 2023 WorkerTask("Shenandoah Update References"), 2024 _heap(ShenandoahHeap::heap()), 2025 _regions(regions) { 2026 } 2027 2028 void work(uint worker_id) { 2029 if (CONCURRENT) { 2030 ShenandoahConcurrentWorkerSession worker_session(worker_id); 2031 ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers); 2032 do_work<ShenandoahConcUpdateRefsClosure>(); 2033 } else { 2034 ShenandoahParallelWorkerSession worker_session(worker_id); 2035 do_work<ShenandoahSTWUpdateRefsClosure>(); 2036 } 2037 } 2038 2039 private: 2040 template<class T> 2041 void do_work() { 2042 T cl; 2043 ShenandoahHeapRegion* r = _regions->next(); 2044 ShenandoahMarkingContext* const ctx = _heap->complete_marking_context(); 2045 while (r != nullptr) { 2046 HeapWord* update_watermark = r->get_update_watermark(); 2047 assert (update_watermark >= r->bottom(), "sanity"); 2048 if (r->is_active() && !r->is_cset()) { 2049 _heap->marked_object_oop_iterate(r, &cl, update_watermark); 2050 } 2051 if (ShenandoahPacing) { 2052 _heap->pacer()->report_updaterefs(pointer_delta(update_watermark, r->bottom())); 2053 } 2054 if (_heap->check_cancelled_gc_and_yield(CONCURRENT)) { 2055 return; 2056 } 2057 r = _regions->next(); 2058 } 2059 } 2060 }; 2061 2062 void ShenandoahHeap::update_heap_references(bool concurrent) { 2063 assert(!is_full_gc_in_progress(), "Only for concurrent and degenerated GC"); 2064 2065 if (concurrent) { 2066 ShenandoahUpdateHeapRefsTask<true> task(&_update_refs_iterator); 2067 workers()->run_task(&task); 2068 } else { 2069 ShenandoahUpdateHeapRefsTask<false> task(&_update_refs_iterator); 2070 workers()->run_task(&task); 2071 } 2072 } 2073 2074 2075 class ShenandoahFinalUpdateRefsUpdateRegionStateClosure : public ShenandoahHeapRegionClosure { 2076 private: 2077 ShenandoahHeapLock* const _lock; 2078 2079 public: 2080 ShenandoahFinalUpdateRefsUpdateRegionStateClosure() : _lock(ShenandoahHeap::heap()->lock()) {} 2081 2082 void heap_region_do(ShenandoahHeapRegion* r) { 2083 // Drop unnecessary "pinned" state from regions that does not have CP marks 2084 // anymore, as this would allow trashing them. 2085 2086 if (r->is_active()) { 2087 if (r->is_pinned()) { 2088 if (r->pin_count() == 0) { 2089 ShenandoahHeapLocker locker(_lock); 2090 r->make_unpinned(); 2091 } 2092 } else { 2093 if (r->pin_count() > 0) { 2094 ShenandoahHeapLocker locker(_lock); 2095 r->make_pinned(); 2096 } 2097 } 2098 } 2099 } 2100 2101 bool is_thread_safe() { return true; } 2102 }; 2103 2104 void ShenandoahHeap::update_heap_region_states(bool concurrent) { 2105 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint"); 2106 assert(!is_full_gc_in_progress(), "Only for concurrent and degenerated GC"); 2107 2108 { 2109 ShenandoahGCPhase phase(concurrent ? 2110 ShenandoahPhaseTimings::final_update_refs_update_region_states : 2111 ShenandoahPhaseTimings::degen_gc_final_update_refs_update_region_states); 2112 ShenandoahFinalUpdateRefsUpdateRegionStateClosure cl; 2113 parallel_heap_region_iterate(&cl); 2114 2115 assert_pinned_region_status(); 2116 } 2117 2118 { 2119 ShenandoahGCPhase phase(concurrent ? 2120 ShenandoahPhaseTimings::final_update_refs_trash_cset : 2121 ShenandoahPhaseTimings::degen_gc_final_update_refs_trash_cset); 2122 trash_cset_regions(); 2123 } 2124 } 2125 2126 void ShenandoahHeap::rebuild_free_set(bool concurrent) { 2127 { 2128 ShenandoahGCPhase phase(concurrent ? 2129 ShenandoahPhaseTimings::final_update_refs_rebuild_freeset : 2130 ShenandoahPhaseTimings::degen_gc_final_update_refs_rebuild_freeset); 2131 ShenandoahHeapLocker locker(lock()); 2132 _free_set->rebuild(); 2133 } 2134 } 2135 2136 void ShenandoahHeap::print_extended_on(outputStream *st) const { 2137 print_on(st); 2138 print_heap_regions_on(st); 2139 } 2140 2141 bool ShenandoahHeap::is_bitmap_slice_committed(ShenandoahHeapRegion* r, bool skip_self) { 2142 size_t slice = r->index() / _bitmap_regions_per_slice; 2143 2144 size_t regions_from = _bitmap_regions_per_slice * slice; 2145 size_t regions_to = MIN2(num_regions(), _bitmap_regions_per_slice * (slice + 1)); 2146 for (size_t g = regions_from; g < regions_to; g++) { 2147 assert (g / _bitmap_regions_per_slice == slice, "same slice"); 2148 if (skip_self && g == r->index()) continue; 2149 if (get_region(g)->is_committed()) { 2150 return true; 2151 } 2152 } 2153 return false; 2154 } 2155 2156 bool ShenandoahHeap::commit_bitmap_slice(ShenandoahHeapRegion* r) { 2157 shenandoah_assert_heaplocked(); 2158 2159 // Bitmaps in special regions do not need commits 2160 if (_bitmap_region_special) { 2161 return true; 2162 } 2163 2164 if (is_bitmap_slice_committed(r, true)) { 2165 // Some other region from the group is already committed, meaning the bitmap 2166 // slice is already committed, we exit right away. 2167 return true; 2168 } 2169 2170 // Commit the bitmap slice: 2171 size_t slice = r->index() / _bitmap_regions_per_slice; 2172 size_t off = _bitmap_bytes_per_slice * slice; 2173 size_t len = _bitmap_bytes_per_slice; 2174 char* start = (char*) _bitmap_region.start() + off; 2175 2176 if (!os::commit_memory(start, len, false)) { 2177 return false; 2178 } 2179 2180 if (AlwaysPreTouch) { 2181 os::pretouch_memory(start, start + len, _pretouch_bitmap_page_size); 2182 } 2183 2184 return true; 2185 } 2186 2187 bool ShenandoahHeap::uncommit_bitmap_slice(ShenandoahHeapRegion *r) { 2188 shenandoah_assert_heaplocked(); 2189 2190 // Bitmaps in special regions do not need uncommits 2191 if (_bitmap_region_special) { 2192 return true; 2193 } 2194 2195 if (is_bitmap_slice_committed(r, true)) { 2196 // Some other region from the group is still committed, meaning the bitmap 2197 // slice is should stay committed, exit right away. 2198 return true; 2199 } 2200 2201 // Uncommit the bitmap slice: 2202 size_t slice = r->index() / _bitmap_regions_per_slice; 2203 size_t off = _bitmap_bytes_per_slice * slice; 2204 size_t len = _bitmap_bytes_per_slice; 2205 if (!os::uncommit_memory((char*)_bitmap_region.start() + off, len)) { 2206 return false; 2207 } 2208 return true; 2209 } 2210 2211 void ShenandoahHeap::safepoint_synchronize_begin() { 2212 if (ShenandoahSuspendibleWorkers || UseStringDeduplication) { 2213 SuspendibleThreadSet::synchronize(); 2214 } 2215 } 2216 2217 void ShenandoahHeap::safepoint_synchronize_end() { 2218 if (ShenandoahSuspendibleWorkers || UseStringDeduplication) { 2219 SuspendibleThreadSet::desynchronize(); 2220 } 2221 } 2222 2223 void ShenandoahHeap::entry_uncommit(double shrink_before, size_t shrink_until) { 2224 static const char *msg = "Concurrent uncommit"; 2225 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_uncommit, true /* log_heap_usage */); 2226 EventMark em("%s", msg); 2227 2228 op_uncommit(shrink_before, shrink_until); 2229 } 2230 2231 void ShenandoahHeap::try_inject_alloc_failure() { 2232 if (ShenandoahAllocFailureALot && !cancelled_gc() && ((os::random() % 1000) > 950)) { 2233 _inject_alloc_failure.set(); 2234 os::naked_short_sleep(1); 2235 if (cancelled_gc()) { 2236 log_info(gc)("Allocation failure was successfully injected"); 2237 } 2238 } 2239 } 2240 2241 bool ShenandoahHeap::should_inject_alloc_failure() { 2242 return _inject_alloc_failure.is_set() && _inject_alloc_failure.try_unset(); 2243 } 2244 2245 void ShenandoahHeap::initialize_serviceability() { 2246 _memory_pool = new ShenandoahMemoryPool(this); 2247 _cycle_memory_manager.add_pool(_memory_pool); 2248 _stw_memory_manager.add_pool(_memory_pool); 2249 } 2250 2251 GrowableArray<GCMemoryManager*> ShenandoahHeap::memory_managers() { 2252 GrowableArray<GCMemoryManager*> memory_managers(2); 2253 memory_managers.append(&_cycle_memory_manager); 2254 memory_managers.append(&_stw_memory_manager); 2255 return memory_managers; 2256 } 2257 2258 GrowableArray<MemoryPool*> ShenandoahHeap::memory_pools() { 2259 GrowableArray<MemoryPool*> memory_pools(1); 2260 memory_pools.append(_memory_pool); 2261 return memory_pools; 2262 } 2263 2264 MemoryUsage ShenandoahHeap::memory_usage() { 2265 return _memory_pool->get_memory_usage(); 2266 } 2267 2268 ShenandoahRegionIterator::ShenandoahRegionIterator() : 2269 _heap(ShenandoahHeap::heap()), 2270 _index(0) {} 2271 2272 ShenandoahRegionIterator::ShenandoahRegionIterator(ShenandoahHeap* heap) : 2273 _heap(heap), 2274 _index(0) {} 2275 2276 void ShenandoahRegionIterator::reset() { 2277 _index = 0; 2278 } 2279 2280 bool ShenandoahRegionIterator::has_next() const { 2281 return _index < _heap->num_regions(); 2282 } 2283 2284 char ShenandoahHeap::gc_state() const { 2285 return _gc_state.raw_value(); 2286 } 2287 2288 ShenandoahLiveData* ShenandoahHeap::get_liveness_cache(uint worker_id) { 2289 #ifdef ASSERT 2290 assert(_liveness_cache != nullptr, "sanity"); 2291 assert(worker_id < _max_workers, "sanity"); 2292 for (uint i = 0; i < num_regions(); i++) { 2293 assert(_liveness_cache[worker_id][i] == 0, "liveness cache should be empty"); 2294 } 2295 #endif 2296 return _liveness_cache[worker_id]; 2297 } 2298 2299 void ShenandoahHeap::flush_liveness_cache(uint worker_id) { 2300 assert(worker_id < _max_workers, "sanity"); 2301 assert(_liveness_cache != nullptr, "sanity"); 2302 ShenandoahLiveData* ld = _liveness_cache[worker_id]; 2303 for (uint i = 0; i < num_regions(); i++) { 2304 ShenandoahLiveData live = ld[i]; 2305 if (live > 0) { 2306 ShenandoahHeapRegion* r = get_region(i); 2307 r->increase_live_data_gc_words(live); 2308 ld[i] = 0; 2309 } 2310 } 2311 } 2312 2313 bool ShenandoahHeap::requires_barriers(stackChunkOop obj) const { 2314 if (is_idle()) return false; 2315 2316 // Objects allocated after marking start are implicitly alive, don't need any barriers during 2317 // marking phase. 2318 if (is_concurrent_mark_in_progress() && 2319 !marking_context()->allocated_after_mark_start(obj)) { 2320 return true; 2321 } 2322 2323 // Can not guarantee obj is deeply good. 2324 if (has_forwarded_objects()) { 2325 return true; 2326 } 2327 2328 return false; 2329 }