1 /* 2 * Copyright (c) 2013, 2021, Red Hat, Inc. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "memory/allocation.hpp" 27 #include "memory/universe.hpp" 28 29 #include "gc/shared/gcArguments.hpp" 30 #include "gc/shared/gcTimer.hpp" 31 #include "gc/shared/gcTraceTime.inline.hpp" 32 #include "gc/shared/locationPrinter.inline.hpp" 33 #include "gc/shared/memAllocator.hpp" 34 #include "gc/shared/plab.hpp" 35 #include "gc/shared/tlab_globals.hpp" 36 37 #include "gc/shenandoah/shenandoahBarrierSet.hpp" 38 #include "gc/shenandoah/shenandoahClosures.inline.hpp" 39 #include "gc/shenandoah/shenandoahCollectionSet.hpp" 40 #include "gc/shenandoah/shenandoahCollectorPolicy.hpp" 41 #include "gc/shenandoah/shenandoahConcurrentMark.hpp" 42 #include "gc/shenandoah/shenandoahControlThread.hpp" 43 #include "gc/shenandoah/shenandoahFreeSet.hpp" 44 #include "gc/shenandoah/shenandoahPhaseTimings.hpp" 45 #include "gc/shenandoah/shenandoahHeap.inline.hpp" 46 #include "gc/shenandoah/shenandoahHeapRegion.inline.hpp" 47 #include "gc/shenandoah/shenandoahHeapRegionSet.hpp" 48 #include "gc/shenandoah/shenandoahInitLogger.hpp" 49 #include "gc/shenandoah/shenandoahMarkingContext.inline.hpp" 50 #include "gc/shenandoah/shenandoahMemoryPool.hpp" 51 #include "gc/shenandoah/shenandoahMetrics.hpp" 52 #include "gc/shenandoah/shenandoahMonitoringSupport.hpp" 53 #include "gc/shenandoah/shenandoahOopClosures.inline.hpp" 54 #include "gc/shenandoah/shenandoahPacer.inline.hpp" 55 #include "gc/shenandoah/shenandoahPadding.hpp" 56 #include "gc/shenandoah/shenandoahParallelCleaning.inline.hpp" 57 #include "gc/shenandoah/shenandoahReferenceProcessor.hpp" 58 #include "gc/shenandoah/shenandoahRootProcessor.inline.hpp" 59 #include "gc/shenandoah/shenandoahStringDedup.hpp" 60 #include "gc/shenandoah/shenandoahSTWMark.hpp" 61 #include "gc/shenandoah/shenandoahUtils.hpp" 62 #include "gc/shenandoah/shenandoahVerifier.hpp" 63 #include "gc/shenandoah/shenandoahCodeRoots.hpp" 64 #include "gc/shenandoah/shenandoahVMOperations.hpp" 65 #include "gc/shenandoah/shenandoahWorkGroup.hpp" 66 #include "gc/shenandoah/shenandoahWorkerPolicy.hpp" 67 #include "gc/shenandoah/mode/shenandoahIUMode.hpp" 68 #include "gc/shenandoah/mode/shenandoahPassiveMode.hpp" 69 #include "gc/shenandoah/mode/shenandoahSATBMode.hpp" 70 #if INCLUDE_JFR 71 #include "gc/shenandoah/shenandoahJfrSupport.hpp" 72 #endif 73 74 #include "classfile/systemDictionary.hpp" 75 #include "memory/classLoaderMetaspace.hpp" 76 #include "memory/metaspaceUtils.hpp" 77 #include "oops/compressedOops.inline.hpp" 78 #include "prims/jvmtiTagMap.hpp" 79 #include "runtime/atomic.hpp" 80 #include "runtime/globals.hpp" 81 #include "runtime/interfaceSupport.inline.hpp" 82 #include "runtime/java.hpp" 83 #include "runtime/orderAccess.hpp" 84 #include "runtime/safepointMechanism.hpp" 85 #include "runtime/vmThread.hpp" 86 #include "services/mallocTracker.hpp" 87 #include "services/memTracker.hpp" 88 #include "utilities/events.hpp" 89 #include "utilities/powerOfTwo.hpp" 90 91 class ShenandoahPretouchHeapTask : public AbstractGangTask { 92 private: 93 ShenandoahRegionIterator _regions; 94 const size_t _page_size; 95 public: 96 ShenandoahPretouchHeapTask(size_t page_size) : 97 AbstractGangTask("Shenandoah Pretouch Heap"), 98 _page_size(page_size) {} 99 100 virtual void work(uint worker_id) { 101 ShenandoahHeapRegion* r = _regions.next(); 102 while (r != NULL) { 103 if (r->is_committed()) { 104 os::pretouch_memory(r->bottom(), r->end(), _page_size); 105 } 106 r = _regions.next(); 107 } 108 } 109 }; 110 111 class ShenandoahPretouchBitmapTask : public AbstractGangTask { 112 private: 113 ShenandoahRegionIterator _regions; 114 char* _bitmap_base; 115 const size_t _bitmap_size; 116 const size_t _page_size; 117 public: 118 ShenandoahPretouchBitmapTask(char* bitmap_base, size_t bitmap_size, size_t page_size) : 119 AbstractGangTask("Shenandoah Pretouch Bitmap"), 120 _bitmap_base(bitmap_base), 121 _bitmap_size(bitmap_size), 122 _page_size(page_size) {} 123 124 virtual void work(uint worker_id) { 125 ShenandoahHeapRegion* r = _regions.next(); 126 while (r != NULL) { 127 size_t start = r->index() * ShenandoahHeapRegion::region_size_bytes() / MarkBitMap::heap_map_factor(); 128 size_t end = (r->index() + 1) * ShenandoahHeapRegion::region_size_bytes() / MarkBitMap::heap_map_factor(); 129 assert (end <= _bitmap_size, "end is sane: " SIZE_FORMAT " < " SIZE_FORMAT, end, _bitmap_size); 130 131 if (r->is_committed()) { 132 os::pretouch_memory(_bitmap_base + start, _bitmap_base + end, _page_size); 133 } 134 135 r = _regions.next(); 136 } 137 } 138 }; 139 140 jint ShenandoahHeap::initialize() { 141 // 142 // Figure out heap sizing 143 // 144 145 size_t init_byte_size = InitialHeapSize; 146 size_t min_byte_size = MinHeapSize; 147 size_t max_byte_size = MaxHeapSize; 148 size_t heap_alignment = HeapAlignment; 149 150 size_t reg_size_bytes = ShenandoahHeapRegion::region_size_bytes(); 151 152 Universe::check_alignment(max_byte_size, reg_size_bytes, "Shenandoah heap"); 153 Universe::check_alignment(init_byte_size, reg_size_bytes, "Shenandoah heap"); 154 155 _num_regions = ShenandoahHeapRegion::region_count(); 156 assert(_num_regions == (max_byte_size / reg_size_bytes), 157 "Regions should cover entire heap exactly: " SIZE_FORMAT " != " SIZE_FORMAT "/" SIZE_FORMAT, 158 _num_regions, max_byte_size, reg_size_bytes); 159 160 // Now we know the number of regions, initialize the heuristics. 161 initialize_heuristics(); 162 163 size_t num_committed_regions = init_byte_size / reg_size_bytes; 164 num_committed_regions = MIN2(num_committed_regions, _num_regions); 165 assert(num_committed_regions <= _num_regions, "sanity"); 166 _initial_size = num_committed_regions * reg_size_bytes; 167 168 size_t num_min_regions = min_byte_size / reg_size_bytes; 169 num_min_regions = MIN2(num_min_regions, _num_regions); 170 assert(num_min_regions <= _num_regions, "sanity"); 171 _minimum_size = num_min_regions * reg_size_bytes; 172 173 // Default to max heap size. 174 _soft_max_size = _num_regions * reg_size_bytes; 175 176 _committed = _initial_size; 177 178 size_t heap_page_size = UseLargePages ? (size_t)os::large_page_size() : (size_t)os::vm_page_size(); 179 size_t bitmap_page_size = UseLargePages ? (size_t)os::large_page_size() : (size_t)os::vm_page_size(); 180 size_t region_page_size = UseLargePages ? (size_t)os::large_page_size() : (size_t)os::vm_page_size(); 181 182 // 183 // Reserve and commit memory for heap 184 // 185 186 ReservedHeapSpace heap_rs = Universe::reserve_heap(max_byte_size, heap_alignment); 187 initialize_reserved_region(heap_rs); 188 _heap_region = MemRegion((HeapWord*)heap_rs.base(), heap_rs.size() / HeapWordSize); 189 _heap_region_special = heap_rs.special(); 190 191 assert((((size_t) base()) & ShenandoahHeapRegion::region_size_bytes_mask()) == 0, 192 "Misaligned heap: " PTR_FORMAT, p2i(base())); 193 194 #if SHENANDOAH_OPTIMIZED_MARKTASK 195 // The optimized ShenandoahMarkTask takes some bits away from the full object bits. 196 // Fail if we ever attempt to address more than we can. 197 if ((uintptr_t)heap_rs.end() >= ShenandoahMarkTask::max_addressable()) { 198 FormatBuffer<512> buf("Shenandoah reserved [" PTR_FORMAT ", " PTR_FORMAT") for the heap, \n" 199 "but max object address is " PTR_FORMAT ". Try to reduce heap size, or try other \n" 200 "VM options that allocate heap at lower addresses (HeapBaseMinAddress, AllocateHeapAt, etc).", 201 p2i(heap_rs.base()), p2i(heap_rs.end()), ShenandoahMarkTask::max_addressable()); 202 vm_exit_during_initialization("Fatal Error", buf); 203 } 204 #endif 205 206 ReservedSpace sh_rs = heap_rs.first_part(max_byte_size); 207 if (!_heap_region_special) { 208 os::commit_memory_or_exit(sh_rs.base(), _initial_size, heap_alignment, false, 209 "Cannot commit heap memory"); 210 } 211 212 // 213 // Reserve and commit memory for bitmap(s) 214 // 215 216 _bitmap_size = ShenandoahMarkBitMap::compute_size(heap_rs.size()); 217 _bitmap_size = align_up(_bitmap_size, bitmap_page_size); 218 219 size_t bitmap_bytes_per_region = reg_size_bytes / ShenandoahMarkBitMap::heap_map_factor(); 220 221 guarantee(bitmap_bytes_per_region != 0, 222 "Bitmap bytes per region should not be zero"); 223 guarantee(is_power_of_2(bitmap_bytes_per_region), 224 "Bitmap bytes per region should be power of two: " SIZE_FORMAT, bitmap_bytes_per_region); 225 226 if (bitmap_page_size > bitmap_bytes_per_region) { 227 _bitmap_regions_per_slice = bitmap_page_size / bitmap_bytes_per_region; 228 _bitmap_bytes_per_slice = bitmap_page_size; 229 } else { 230 _bitmap_regions_per_slice = 1; 231 _bitmap_bytes_per_slice = bitmap_bytes_per_region; 232 } 233 234 guarantee(_bitmap_regions_per_slice >= 1, 235 "Should have at least one region per slice: " SIZE_FORMAT, 236 _bitmap_regions_per_slice); 237 238 guarantee(((_bitmap_bytes_per_slice) % bitmap_page_size) == 0, 239 "Bitmap slices should be page-granular: bps = " SIZE_FORMAT ", page size = " SIZE_FORMAT, 240 _bitmap_bytes_per_slice, bitmap_page_size); 241 242 ReservedSpace bitmap(_bitmap_size, bitmap_page_size); 243 MemTracker::record_virtual_memory_type(bitmap.base(), mtGC); 244 _bitmap_region = MemRegion((HeapWord*) bitmap.base(), bitmap.size() / HeapWordSize); 245 _bitmap_region_special = bitmap.special(); 246 247 size_t bitmap_init_commit = _bitmap_bytes_per_slice * 248 align_up(num_committed_regions, _bitmap_regions_per_slice) / _bitmap_regions_per_slice; 249 bitmap_init_commit = MIN2(_bitmap_size, bitmap_init_commit); 250 if (!_bitmap_region_special) { 251 os::commit_memory_or_exit((char *) _bitmap_region.start(), bitmap_init_commit, bitmap_page_size, false, 252 "Cannot commit bitmap memory"); 253 } 254 255 _marking_context = new ShenandoahMarkingContext(_heap_region, _bitmap_region, _num_regions, _max_workers); 256 257 if (ShenandoahVerify) { 258 ReservedSpace verify_bitmap(_bitmap_size, bitmap_page_size); 259 if (!verify_bitmap.special()) { 260 os::commit_memory_or_exit(verify_bitmap.base(), verify_bitmap.size(), bitmap_page_size, false, 261 "Cannot commit verification bitmap memory"); 262 } 263 MemTracker::record_virtual_memory_type(verify_bitmap.base(), mtGC); 264 MemRegion verify_bitmap_region = MemRegion((HeapWord *) verify_bitmap.base(), verify_bitmap.size() / HeapWordSize); 265 _verification_bit_map.initialize(_heap_region, verify_bitmap_region); 266 _verifier = new ShenandoahVerifier(this, &_verification_bit_map); 267 } 268 269 // Reserve aux bitmap for use in object_iterate(). We don't commit it here. 270 ReservedSpace aux_bitmap(_bitmap_size, bitmap_page_size); 271 MemTracker::record_virtual_memory_type(aux_bitmap.base(), mtGC); 272 _aux_bitmap_region = MemRegion((HeapWord*) aux_bitmap.base(), aux_bitmap.size() / HeapWordSize); 273 _aux_bitmap_region_special = aux_bitmap.special(); 274 _aux_bit_map.initialize(_heap_region, _aux_bitmap_region); 275 276 // 277 // Create regions and region sets 278 // 279 size_t region_align = align_up(sizeof(ShenandoahHeapRegion), SHENANDOAH_CACHE_LINE_SIZE); 280 size_t region_storage_size = align_up(region_align * _num_regions, region_page_size); 281 region_storage_size = align_up(region_storage_size, os::vm_allocation_granularity()); 282 283 ReservedSpace region_storage(region_storage_size, region_page_size); 284 MemTracker::record_virtual_memory_type(region_storage.base(), mtGC); 285 if (!region_storage.special()) { 286 os::commit_memory_or_exit(region_storage.base(), region_storage_size, region_page_size, false, 287 "Cannot commit region memory"); 288 } 289 290 // Try to fit the collection set bitmap at lower addresses. This optimizes code generation for cset checks. 291 // Go up until a sensible limit (subject to encoding constraints) and try to reserve the space there. 292 // If not successful, bite a bullet and allocate at whatever address. 293 { 294 size_t cset_align = MAX2<size_t>(os::vm_page_size(), os::vm_allocation_granularity()); 295 size_t cset_size = align_up(((size_t) sh_rs.base() + sh_rs.size()) >> ShenandoahHeapRegion::region_size_bytes_shift(), cset_align); 296 297 uintptr_t min = round_up_power_of_2(cset_align); 298 uintptr_t max = (1u << 30u); 299 300 for (uintptr_t addr = min; addr <= max; addr <<= 1u) { 301 char* req_addr = (char*)addr; 302 assert(is_aligned(req_addr, cset_align), "Should be aligned"); 303 ReservedSpace cset_rs(cset_size, cset_align, os::vm_page_size(), req_addr); 304 if (cset_rs.is_reserved()) { 305 assert(cset_rs.base() == req_addr, "Allocated where requested: " PTR_FORMAT ", " PTR_FORMAT, p2i(cset_rs.base()), addr); 306 _collection_set = new ShenandoahCollectionSet(this, cset_rs, sh_rs.base()); 307 break; 308 } 309 } 310 311 if (_collection_set == NULL) { 312 ReservedSpace cset_rs(cset_size, cset_align, os::vm_page_size()); 313 _collection_set = new ShenandoahCollectionSet(this, cset_rs, sh_rs.base()); 314 } 315 } 316 317 _regions = NEW_C_HEAP_ARRAY(ShenandoahHeapRegion*, _num_regions, mtGC); 318 _free_set = new ShenandoahFreeSet(this, _num_regions); 319 320 { 321 ShenandoahHeapLocker locker(lock()); 322 323 for (size_t i = 0; i < _num_regions; i++) { 324 HeapWord* start = (HeapWord*)sh_rs.base() + ShenandoahHeapRegion::region_size_words() * i; 325 bool is_committed = i < num_committed_regions; 326 void* loc = region_storage.base() + i * region_align; 327 328 ShenandoahHeapRegion* r = new (loc) ShenandoahHeapRegion(start, i, is_committed); 329 assert(is_aligned(r, SHENANDOAH_CACHE_LINE_SIZE), "Sanity"); 330 331 _marking_context->initialize_top_at_mark_start(r); 332 _regions[i] = r; 333 assert(!collection_set()->is_in(i), "New region should not be in collection set"); 334 } 335 336 // Initialize to complete 337 _marking_context->mark_complete(); 338 339 _free_set->rebuild(); 340 } 341 342 if (AlwaysPreTouch) { 343 // For NUMA, it is important to pre-touch the storage under bitmaps with worker threads, 344 // before initialize() below zeroes it with initializing thread. For any given region, 345 // we touch the region and the corresponding bitmaps from the same thread. 346 ShenandoahPushWorkerScope scope(workers(), _max_workers, false); 347 348 _pretouch_heap_page_size = heap_page_size; 349 _pretouch_bitmap_page_size = bitmap_page_size; 350 351 #ifdef LINUX 352 // UseTransparentHugePages would madvise that backing memory can be coalesced into huge 353 // pages. But, the kernel needs to know that every small page is used, in order to coalesce 354 // them into huge one. Therefore, we need to pretouch with smaller pages. 355 if (UseTransparentHugePages) { 356 _pretouch_heap_page_size = (size_t)os::vm_page_size(); 357 _pretouch_bitmap_page_size = (size_t)os::vm_page_size(); 358 } 359 #endif 360 361 // OS memory managers may want to coalesce back-to-back pages. Make their jobs 362 // simpler by pre-touching continuous spaces (heap and bitmap) separately. 363 364 ShenandoahPretouchBitmapTask bcl(bitmap.base(), _bitmap_size, _pretouch_bitmap_page_size); 365 _workers->run_task(&bcl); 366 367 ShenandoahPretouchHeapTask hcl(_pretouch_heap_page_size); 368 _workers->run_task(&hcl); 369 } 370 371 // 372 // Initialize the rest of GC subsystems 373 // 374 375 _liveness_cache = NEW_C_HEAP_ARRAY(ShenandoahLiveData*, _max_workers, mtGC); 376 for (uint worker = 0; worker < _max_workers; worker++) { 377 _liveness_cache[worker] = NEW_C_HEAP_ARRAY(ShenandoahLiveData, _num_regions, mtGC); 378 Copy::fill_to_bytes(_liveness_cache[worker], _num_regions * sizeof(ShenandoahLiveData)); 379 } 380 381 // There should probably be Shenandoah-specific options for these, 382 // just as there are G1-specific options. 383 { 384 ShenandoahSATBMarkQueueSet& satbqs = ShenandoahBarrierSet::satb_mark_queue_set(); 385 satbqs.set_process_completed_buffers_threshold(20); // G1SATBProcessCompletedThreshold 386 satbqs.set_buffer_enqueue_threshold_percentage(60); // G1SATBBufferEnqueueingThresholdPercent 387 } 388 389 _monitoring_support = new ShenandoahMonitoringSupport(this); 390 _phase_timings = new ShenandoahPhaseTimings(max_workers()); 391 ShenandoahCodeRoots::initialize(); 392 393 if (ShenandoahPacing) { 394 _pacer = new ShenandoahPacer(this); 395 _pacer->setup_for_idle(); 396 } else { 397 _pacer = NULL; 398 } 399 400 _control_thread = new ShenandoahControlThread(); 401 402 ShenandoahInitLogger::print(); 403 404 return JNI_OK; 405 } 406 407 void ShenandoahHeap::initialize_mode() { 408 if (ShenandoahGCMode != NULL) { 409 if (strcmp(ShenandoahGCMode, "satb") == 0) { 410 _gc_mode = new ShenandoahSATBMode(); 411 } else if (strcmp(ShenandoahGCMode, "iu") == 0) { 412 _gc_mode = new ShenandoahIUMode(); 413 } else if (strcmp(ShenandoahGCMode, "passive") == 0) { 414 _gc_mode = new ShenandoahPassiveMode(); 415 } else { 416 vm_exit_during_initialization("Unknown -XX:ShenandoahGCMode option"); 417 } 418 } else { 419 vm_exit_during_initialization("Unknown -XX:ShenandoahGCMode option (null)"); 420 } 421 _gc_mode->initialize_flags(); 422 if (_gc_mode->is_diagnostic() && !UnlockDiagnosticVMOptions) { 423 vm_exit_during_initialization( 424 err_msg("GC mode \"%s\" is diagnostic, and must be enabled via -XX:+UnlockDiagnosticVMOptions.", 425 _gc_mode->name())); 426 } 427 if (_gc_mode->is_experimental() && !UnlockExperimentalVMOptions) { 428 vm_exit_during_initialization( 429 err_msg("GC mode \"%s\" is experimental, and must be enabled via -XX:+UnlockExperimentalVMOptions.", 430 _gc_mode->name())); 431 } 432 } 433 434 void ShenandoahHeap::initialize_heuristics() { 435 assert(_gc_mode != NULL, "Must be initialized"); 436 _heuristics = _gc_mode->initialize_heuristics(); 437 438 if (_heuristics->is_diagnostic() && !UnlockDiagnosticVMOptions) { 439 vm_exit_during_initialization( 440 err_msg("Heuristics \"%s\" is diagnostic, and must be enabled via -XX:+UnlockDiagnosticVMOptions.", 441 _heuristics->name())); 442 } 443 if (_heuristics->is_experimental() && !UnlockExperimentalVMOptions) { 444 vm_exit_during_initialization( 445 err_msg("Heuristics \"%s\" is experimental, and must be enabled via -XX:+UnlockExperimentalVMOptions.", 446 _heuristics->name())); 447 } 448 } 449 450 #ifdef _MSC_VER 451 #pragma warning( push ) 452 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list 453 #endif 454 455 ShenandoahHeap::ShenandoahHeap(ShenandoahCollectorPolicy* policy) : 456 CollectedHeap(), 457 _initial_size(0), 458 _used(0), 459 _committed(0), 460 _bytes_allocated_since_gc_start(0), 461 _max_workers(MAX2(ConcGCThreads, ParallelGCThreads)), 462 _workers(NULL), 463 _safepoint_workers(NULL), 464 _heap_region_special(false), 465 _num_regions(0), 466 _regions(NULL), 467 _update_refs_iterator(this), 468 _control_thread(NULL), 469 _shenandoah_policy(policy), 470 _gc_mode(NULL), 471 _heuristics(NULL), 472 _free_set(NULL), 473 _pacer(NULL), 474 _verifier(NULL), 475 _phase_timings(NULL), 476 _monitoring_support(NULL), 477 _memory_pool(NULL), 478 _stw_memory_manager("Shenandoah Pauses"), 479 _cycle_memory_manager("Shenandoah Cycles"), 480 _gc_timer(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()), 481 _soft_ref_policy(), 482 _log_min_obj_alignment_in_bytes(LogMinObjAlignmentInBytes), 483 _ref_processor(new ShenandoahReferenceProcessor(MAX2(_max_workers, 1U))), 484 _marking_context(NULL), 485 _bitmap_size(0), 486 _bitmap_regions_per_slice(0), 487 _bitmap_bytes_per_slice(0), 488 _bitmap_region_special(false), 489 _aux_bitmap_region_special(false), 490 _liveness_cache(NULL), 491 _collection_set(NULL) 492 { 493 // Initialize GC mode early, so we can adjust barrier support 494 initialize_mode(); 495 BarrierSet::set_barrier_set(new ShenandoahBarrierSet(this)); 496 497 _max_workers = MAX2(_max_workers, 1U); 498 _workers = new ShenandoahWorkGang("Shenandoah GC Threads", _max_workers, 499 /* are_GC_task_threads */ true, 500 /* are_ConcurrentGC_threads */ true); 501 if (_workers == NULL) { 502 vm_exit_during_initialization("Failed necessary allocation."); 503 } else { 504 _workers->initialize_workers(); 505 } 506 507 if (ParallelGCThreads > 1) { 508 _safepoint_workers = new ShenandoahWorkGang("Safepoint Cleanup Thread", 509 ParallelGCThreads, 510 /* are_GC_task_threads */ false, 511 /* are_ConcurrentGC_threads */ false); 512 _safepoint_workers->initialize_workers(); 513 } 514 } 515 516 #ifdef _MSC_VER 517 #pragma warning( pop ) 518 #endif 519 520 class ShenandoahResetBitmapTask : public AbstractGangTask { 521 private: 522 ShenandoahRegionIterator _regions; 523 524 public: 525 ShenandoahResetBitmapTask() : 526 AbstractGangTask("Shenandoah Reset Bitmap") {} 527 528 void work(uint worker_id) { 529 ShenandoahHeapRegion* region = _regions.next(); 530 ShenandoahHeap* heap = ShenandoahHeap::heap(); 531 ShenandoahMarkingContext* const ctx = heap->marking_context(); 532 while (region != NULL) { 533 if (heap->is_bitmap_slice_committed(region)) { 534 ctx->clear_bitmap(region); 535 } 536 region = _regions.next(); 537 } 538 } 539 }; 540 541 void ShenandoahHeap::reset_mark_bitmap() { 542 assert_gc_workers(_workers->active_workers()); 543 mark_incomplete_marking_context(); 544 545 ShenandoahResetBitmapTask task; 546 _workers->run_task(&task); 547 } 548 549 void ShenandoahHeap::print_on(outputStream* st) const { 550 st->print_cr("Shenandoah Heap"); 551 st->print_cr(" " SIZE_FORMAT "%s max, " SIZE_FORMAT "%s soft max, " SIZE_FORMAT "%s committed, " SIZE_FORMAT "%s used", 552 byte_size_in_proper_unit(max_capacity()), proper_unit_for_byte_size(max_capacity()), 553 byte_size_in_proper_unit(soft_max_capacity()), proper_unit_for_byte_size(soft_max_capacity()), 554 byte_size_in_proper_unit(committed()), proper_unit_for_byte_size(committed()), 555 byte_size_in_proper_unit(used()), proper_unit_for_byte_size(used())); 556 st->print_cr(" " SIZE_FORMAT " x " SIZE_FORMAT"%s regions", 557 num_regions(), 558 byte_size_in_proper_unit(ShenandoahHeapRegion::region_size_bytes()), 559 proper_unit_for_byte_size(ShenandoahHeapRegion::region_size_bytes())); 560 561 st->print("Status: "); 562 if (has_forwarded_objects()) st->print("has forwarded objects, "); 563 if (is_concurrent_mark_in_progress()) st->print("marking, "); 564 if (is_evacuation_in_progress()) st->print("evacuating, "); 565 if (is_update_refs_in_progress()) st->print("updating refs, "); 566 if (is_degenerated_gc_in_progress()) st->print("degenerated gc, "); 567 if (is_full_gc_in_progress()) st->print("full gc, "); 568 if (is_full_gc_move_in_progress()) st->print("full gc move, "); 569 if (is_concurrent_weak_root_in_progress()) st->print("concurrent weak roots, "); 570 if (is_concurrent_strong_root_in_progress() && 571 !is_concurrent_weak_root_in_progress()) st->print("concurrent strong roots, "); 572 573 if (cancelled_gc()) { 574 st->print("cancelled"); 575 } else { 576 st->print("not cancelled"); 577 } 578 st->cr(); 579 580 st->print_cr("Reserved region:"); 581 st->print_cr(" - [" PTR_FORMAT ", " PTR_FORMAT ") ", 582 p2i(reserved_region().start()), 583 p2i(reserved_region().end())); 584 585 ShenandoahCollectionSet* cset = collection_set(); 586 st->print_cr("Collection set:"); 587 if (cset != NULL) { 588 st->print_cr(" - map (vanilla): " PTR_FORMAT, p2i(cset->map_address())); 589 st->print_cr(" - map (biased): " PTR_FORMAT, p2i(cset->biased_map_address())); 590 } else { 591 st->print_cr(" (NULL)"); 592 } 593 594 st->cr(); 595 MetaspaceUtils::print_on(st); 596 597 if (Verbose) { 598 st->cr(); 599 print_heap_regions_on(st); 600 } 601 } 602 603 class ShenandoahInitWorkerGCLABClosure : public ThreadClosure { 604 public: 605 void do_thread(Thread* thread) { 606 assert(thread != NULL, "Sanity"); 607 assert(thread->is_Worker_thread(), "Only worker thread expected"); 608 ShenandoahThreadLocalData::initialize_gclab(thread); 609 } 610 }; 611 612 void ShenandoahHeap::post_initialize() { 613 CollectedHeap::post_initialize(); 614 MutexLocker ml(Threads_lock); 615 616 ShenandoahInitWorkerGCLABClosure init_gclabs; 617 _workers->threads_do(&init_gclabs); 618 619 // gclab can not be initialized early during VM startup, as it can not determinate its max_size. 620 // Now, we will let WorkGang to initialize gclab when new worker is created. 621 _workers->set_initialize_gclab(); 622 if (_safepoint_workers != NULL) { 623 _safepoint_workers->threads_do(&init_gclabs); 624 _safepoint_workers->set_initialize_gclab(); 625 } 626 627 _heuristics->initialize(); 628 629 JFR_ONLY(ShenandoahJFRSupport::register_jfr_type_serializers()); 630 } 631 632 size_t ShenandoahHeap::used() const { 633 return Atomic::load(&_used); 634 } 635 636 size_t ShenandoahHeap::committed() const { 637 return Atomic::load(&_committed); 638 } 639 640 void ShenandoahHeap::increase_committed(size_t bytes) { 641 shenandoah_assert_heaplocked_or_safepoint(); 642 _committed += bytes; 643 } 644 645 void ShenandoahHeap::decrease_committed(size_t bytes) { 646 shenandoah_assert_heaplocked_or_safepoint(); 647 _committed -= bytes; 648 } 649 650 void ShenandoahHeap::increase_used(size_t bytes) { 651 Atomic::add(&_used, bytes, memory_order_relaxed); 652 } 653 654 void ShenandoahHeap::set_used(size_t bytes) { 655 Atomic::store(&_used, bytes); 656 } 657 658 void ShenandoahHeap::decrease_used(size_t bytes) { 659 assert(used() >= bytes, "never decrease heap size by more than we've left"); 660 Atomic::sub(&_used, bytes, memory_order_relaxed); 661 } 662 663 void ShenandoahHeap::increase_allocated(size_t bytes) { 664 Atomic::add(&_bytes_allocated_since_gc_start, bytes, memory_order_relaxed); 665 } 666 667 void ShenandoahHeap::notify_mutator_alloc_words(size_t words, bool waste) { 668 size_t bytes = words * HeapWordSize; 669 if (!waste) { 670 increase_used(bytes); 671 } 672 increase_allocated(bytes); 673 if (ShenandoahPacing) { 674 control_thread()->pacing_notify_alloc(words); 675 if (waste) { 676 pacer()->claim_for_alloc(words, true); 677 } 678 } 679 } 680 681 size_t ShenandoahHeap::capacity() const { 682 return committed(); 683 } 684 685 size_t ShenandoahHeap::max_capacity() const { 686 return _num_regions * ShenandoahHeapRegion::region_size_bytes(); 687 } 688 689 size_t ShenandoahHeap::soft_max_capacity() const { 690 size_t v = Atomic::load(&_soft_max_size); 691 assert(min_capacity() <= v && v <= max_capacity(), 692 "Should be in bounds: " SIZE_FORMAT " <= " SIZE_FORMAT " <= " SIZE_FORMAT, 693 min_capacity(), v, max_capacity()); 694 return v; 695 } 696 697 void ShenandoahHeap::set_soft_max_capacity(size_t v) { 698 assert(min_capacity() <= v && v <= max_capacity(), 699 "Should be in bounds: " SIZE_FORMAT " <= " SIZE_FORMAT " <= " SIZE_FORMAT, 700 min_capacity(), v, max_capacity()); 701 Atomic::store(&_soft_max_size, v); 702 } 703 704 size_t ShenandoahHeap::min_capacity() const { 705 return _minimum_size; 706 } 707 708 size_t ShenandoahHeap::initial_capacity() const { 709 return _initial_size; 710 } 711 712 bool ShenandoahHeap::is_in(const void* p) const { 713 HeapWord* heap_base = (HeapWord*) base(); 714 HeapWord* last_region_end = heap_base + ShenandoahHeapRegion::region_size_words() * num_regions(); 715 return p >= heap_base && p < last_region_end; 716 } 717 718 void ShenandoahHeap::op_uncommit(double shrink_before, size_t shrink_until) { 719 assert (ShenandoahUncommit, "should be enabled"); 720 721 // Application allocates from the beginning of the heap, and GC allocates at 722 // the end of it. It is more efficient to uncommit from the end, so that applications 723 // could enjoy the near committed regions. GC allocations are much less frequent, 724 // and therefore can accept the committing costs. 725 726 size_t count = 0; 727 for (size_t i = num_regions(); i > 0; i--) { // care about size_t underflow 728 ShenandoahHeapRegion* r = get_region(i - 1); 729 if (r->is_empty_committed() && (r->empty_time() < shrink_before)) { 730 ShenandoahHeapLocker locker(lock()); 731 if (r->is_empty_committed()) { 732 if (committed() < shrink_until + ShenandoahHeapRegion::region_size_bytes()) { 733 break; 734 } 735 736 r->make_uncommitted(); 737 count++; 738 } 739 } 740 SpinPause(); // allow allocators to take the lock 741 } 742 743 if (count > 0) { 744 control_thread()->notify_heap_changed(); 745 } 746 } 747 748 HeapWord* ShenandoahHeap::allocate_from_gclab_slow(Thread* thread, size_t size) { 749 // New object should fit the GCLAB size 750 size_t min_size = MAX2(size, PLAB::min_size()); 751 752 // Figure out size of new GCLAB, looking back at heuristics. Expand aggressively. 753 size_t new_size = ShenandoahThreadLocalData::gclab_size(thread) * 2; 754 new_size = MIN2(new_size, PLAB::max_size()); 755 new_size = MAX2(new_size, PLAB::min_size()); 756 757 // Record new heuristic value even if we take any shortcut. This captures 758 // the case when moderately-sized objects always take a shortcut. At some point, 759 // heuristics should catch up with them. 760 ShenandoahThreadLocalData::set_gclab_size(thread, new_size); 761 762 if (new_size < size) { 763 // New size still does not fit the object. Fall back to shared allocation. 764 // This avoids retiring perfectly good GCLABs, when we encounter a large object. 765 return NULL; 766 } 767 768 // Retire current GCLAB, and allocate a new one. 769 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread); 770 gclab->retire(); 771 772 size_t actual_size = 0; 773 HeapWord* gclab_buf = allocate_new_gclab(min_size, new_size, &actual_size); 774 if (gclab_buf == NULL) { 775 return NULL; 776 } 777 778 assert (size <= actual_size, "allocation should fit"); 779 780 if (ZeroTLAB) { 781 // ..and clear it. 782 Copy::zero_to_words(gclab_buf, actual_size); 783 } else { 784 // ...and zap just allocated object. 785 #ifdef ASSERT 786 // Skip mangling the space corresponding to the object header to 787 // ensure that the returned space is not considered parsable by 788 // any concurrent GC thread. 789 size_t hdr_size = oopDesc::header_size(); 790 Copy::fill_to_words(gclab_buf + hdr_size, actual_size - hdr_size, badHeapWordVal); 791 #endif // ASSERT 792 } 793 gclab->set_buf(gclab_buf, actual_size); 794 return gclab->allocate(size); 795 } 796 797 HeapWord* ShenandoahHeap::allocate_new_tlab(size_t min_size, 798 size_t requested_size, 799 size_t* actual_size) { 800 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_tlab(min_size, requested_size); 801 HeapWord* res = allocate_memory(req); 802 if (res != NULL) { 803 *actual_size = req.actual_size(); 804 } else { 805 *actual_size = 0; 806 } 807 return res; 808 } 809 810 HeapWord* ShenandoahHeap::allocate_new_gclab(size_t min_size, 811 size_t word_size, 812 size_t* actual_size) { 813 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_gclab(min_size, word_size); 814 HeapWord* res = allocate_memory(req); 815 if (res != NULL) { 816 *actual_size = req.actual_size(); 817 } else { 818 *actual_size = 0; 819 } 820 return res; 821 } 822 823 HeapWord* ShenandoahHeap::allocate_memory(ShenandoahAllocRequest& req) { 824 intptr_t pacer_epoch = 0; 825 bool in_new_region = false; 826 HeapWord* result = NULL; 827 828 if (req.is_mutator_alloc()) { 829 if (ShenandoahPacing) { 830 pacer()->pace_for_alloc(req.size()); 831 pacer_epoch = pacer()->epoch(); 832 } 833 834 if (!ShenandoahAllocFailureALot || !should_inject_alloc_failure()) { 835 result = allocate_memory_under_lock(req, in_new_region); 836 } 837 838 // Allocation failed, block until control thread reacted, then retry allocation. 839 // 840 // It might happen that one of the threads requesting allocation would unblock 841 // way later after GC happened, only to fail the second allocation, because 842 // other threads have already depleted the free storage. In this case, a better 843 // strategy is to try again, as long as GC makes progress. 844 // 845 // Then, we need to make sure the allocation was retried after at least one 846 // Full GC, which means we want to try more than ShenandoahFullGCThreshold times. 847 848 size_t tries = 0; 849 850 while (result == NULL && _progress_last_gc.is_set()) { 851 tries++; 852 control_thread()->handle_alloc_failure(req); 853 result = allocate_memory_under_lock(req, in_new_region); 854 } 855 856 while (result == NULL && tries <= ShenandoahFullGCThreshold) { 857 tries++; 858 control_thread()->handle_alloc_failure(req); 859 result = allocate_memory_under_lock(req, in_new_region); 860 } 861 862 } else { 863 assert(req.is_gc_alloc(), "Can only accept GC allocs here"); 864 result = allocate_memory_under_lock(req, in_new_region); 865 // Do not call handle_alloc_failure() here, because we cannot block. 866 // The allocation failure would be handled by the LRB slowpath with handle_alloc_failure_evac(). 867 } 868 869 if (in_new_region) { 870 control_thread()->notify_heap_changed(); 871 } 872 873 if (result != NULL) { 874 size_t requested = req.size(); 875 size_t actual = req.actual_size(); 876 877 assert (req.is_lab_alloc() || (requested == actual), 878 "Only LAB allocations are elastic: %s, requested = " SIZE_FORMAT ", actual = " SIZE_FORMAT, 879 ShenandoahAllocRequest::alloc_type_to_string(req.type()), requested, actual); 880 881 if (req.is_mutator_alloc()) { 882 notify_mutator_alloc_words(actual, false); 883 884 // If we requested more than we were granted, give the rest back to pacer. 885 // This only matters if we are in the same pacing epoch: do not try to unpace 886 // over the budget for the other phase. 887 if (ShenandoahPacing && (pacer_epoch > 0) && (requested > actual)) { 888 pacer()->unpace_for_alloc(pacer_epoch, requested - actual); 889 } 890 } else { 891 increase_used(actual*HeapWordSize); 892 } 893 } 894 895 return result; 896 } 897 898 HeapWord* ShenandoahHeap::allocate_memory_under_lock(ShenandoahAllocRequest& req, bool& in_new_region) { 899 ShenandoahHeapLocker locker(lock()); 900 return _free_set->allocate(req, in_new_region); 901 } 902 903 HeapWord* ShenandoahHeap::mem_allocate(size_t size, 904 bool* gc_overhead_limit_was_exceeded) { 905 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_shared(size); 906 return allocate_memory(req); 907 } 908 909 MetaWord* ShenandoahHeap::satisfy_failed_metadata_allocation(ClassLoaderData* loader_data, 910 size_t size, 911 Metaspace::MetadataType mdtype) { 912 MetaWord* result; 913 914 // Inform metaspace OOM to GC heuristics if class unloading is possible. 915 if (heuristics()->can_unload_classes()) { 916 ShenandoahHeuristics* h = heuristics(); 917 h->record_metaspace_oom(); 918 } 919 920 // Expand and retry allocation 921 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype); 922 if (result != NULL) { 923 return result; 924 } 925 926 // Start full GC 927 collect(GCCause::_metadata_GC_clear_soft_refs); 928 929 // Retry allocation 930 result = loader_data->metaspace_non_null()->allocate(size, mdtype); 931 if (result != NULL) { 932 return result; 933 } 934 935 // Expand and retry allocation 936 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype); 937 if (result != NULL) { 938 return result; 939 } 940 941 // Out of memory 942 return NULL; 943 } 944 945 class ShenandoahConcurrentEvacuateRegionObjectClosure : public ObjectClosure { 946 private: 947 ShenandoahHeap* const _heap; 948 Thread* const _thread; 949 public: 950 ShenandoahConcurrentEvacuateRegionObjectClosure(ShenandoahHeap* heap) : 951 _heap(heap), _thread(Thread::current()) {} 952 953 void do_object(oop p) { 954 shenandoah_assert_marked(NULL, p); 955 if (!p->is_forwarded()) { 956 _heap->evacuate_object(p, _thread); 957 } 958 } 959 }; 960 961 class ShenandoahEvacuationTask : public AbstractGangTask { 962 private: 963 ShenandoahHeap* const _sh; 964 ShenandoahCollectionSet* const _cs; 965 bool _concurrent; 966 public: 967 ShenandoahEvacuationTask(ShenandoahHeap* sh, 968 ShenandoahCollectionSet* cs, 969 bool concurrent) : 970 AbstractGangTask("Shenandoah Evacuation"), 971 _sh(sh), 972 _cs(cs), 973 _concurrent(concurrent) 974 {} 975 976 void work(uint worker_id) { 977 if (_concurrent) { 978 ShenandoahConcurrentWorkerSession worker_session(worker_id); 979 ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers); 980 ShenandoahEvacOOMScope oom_evac_scope; 981 do_work(); 982 } else { 983 ShenandoahParallelWorkerSession worker_session(worker_id); 984 ShenandoahEvacOOMScope oom_evac_scope; 985 do_work(); 986 } 987 } 988 989 private: 990 void do_work() { 991 ShenandoahConcurrentEvacuateRegionObjectClosure cl(_sh); 992 ShenandoahHeapRegion* r; 993 while ((r =_cs->claim_next()) != NULL) { 994 assert(r->has_live(), "Region " SIZE_FORMAT " should have been reclaimed early", r->index()); 995 _sh->marked_object_iterate(r, &cl); 996 997 if (ShenandoahPacing) { 998 _sh->pacer()->report_evac(r->used() >> LogHeapWordSize); 999 } 1000 1001 if (_sh->check_cancelled_gc_and_yield(_concurrent)) { 1002 break; 1003 } 1004 } 1005 } 1006 }; 1007 1008 void ShenandoahHeap::evacuate_collection_set(bool concurrent) { 1009 ShenandoahEvacuationTask task(this, _collection_set, concurrent); 1010 workers()->run_task(&task); 1011 } 1012 1013 void ShenandoahHeap::trash_cset_regions() { 1014 ShenandoahHeapLocker locker(lock()); 1015 1016 ShenandoahCollectionSet* set = collection_set(); 1017 ShenandoahHeapRegion* r; 1018 set->clear_current_index(); 1019 while ((r = set->next()) != NULL) { 1020 r->make_trash(); 1021 } 1022 collection_set()->clear(); 1023 } 1024 1025 void ShenandoahHeap::print_heap_regions_on(outputStream* st) const { 1026 st->print_cr("Heap Regions:"); 1027 st->print_cr("Region state: EU=empty-uncommitted, EC=empty-committed, R=regular, H=humongous start, HP=pinned humongous start"); 1028 st->print_cr(" HC=humongous continuation, CS=collection set, TR=trash, P=pinned, CSP=pinned collection set"); 1029 st->print_cr("BTE=bottom/top/end, TAMS=top-at-mark-start"); 1030 st->print_cr("UWM=update watermark, U=used"); 1031 st->print_cr("T=TLAB allocs, G=GCLAB allocs"); 1032 st->print_cr("S=shared allocs, L=live data"); 1033 st->print_cr("CP=critical pins"); 1034 1035 for (size_t i = 0; i < num_regions(); i++) { 1036 get_region(i)->print_on(st); 1037 } 1038 } 1039 1040 void ShenandoahHeap::trash_humongous_region_at(ShenandoahHeapRegion* start) { 1041 assert(start->is_humongous_start(), "reclaim regions starting with the first one"); 1042 1043 oop humongous_obj = cast_to_oop(start->bottom()); 1044 size_t size = humongous_obj->size(); 1045 size_t required_regions = ShenandoahHeapRegion::required_regions(size * HeapWordSize); 1046 size_t index = start->index() + required_regions - 1; 1047 1048 assert(!start->has_live(), "liveness must be zero"); 1049 1050 for(size_t i = 0; i < required_regions; i++) { 1051 // Reclaim from tail. Otherwise, assertion fails when printing region to trace log, 1052 // as it expects that every region belongs to a humongous region starting with a humongous start region. 1053 ShenandoahHeapRegion* region = get_region(index --); 1054 1055 assert(region->is_humongous(), "expect correct humongous start or continuation"); 1056 assert(!region->is_cset(), "Humongous region should not be in collection set"); 1057 1058 region->make_trash_immediate(); 1059 } 1060 } 1061 1062 class ShenandoahCheckCleanGCLABClosure : public ThreadClosure { 1063 public: 1064 ShenandoahCheckCleanGCLABClosure() {} 1065 void do_thread(Thread* thread) { 1066 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread); 1067 assert(gclab != NULL, "GCLAB should be initialized for %s", thread->name()); 1068 assert(gclab->words_remaining() == 0, "GCLAB should not need retirement"); 1069 } 1070 }; 1071 1072 class ShenandoahRetireGCLABClosure : public ThreadClosure { 1073 private: 1074 bool const _resize; 1075 public: 1076 ShenandoahRetireGCLABClosure(bool resize) : _resize(resize) {} 1077 void do_thread(Thread* thread) { 1078 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread); 1079 assert(gclab != NULL, "GCLAB should be initialized for %s", thread->name()); 1080 gclab->retire(); 1081 if (_resize && ShenandoahThreadLocalData::gclab_size(thread) > 0) { 1082 ShenandoahThreadLocalData::set_gclab_size(thread, 0); 1083 } 1084 } 1085 }; 1086 1087 void ShenandoahHeap::labs_make_parsable() { 1088 assert(UseTLAB, "Only call with UseTLAB"); 1089 1090 ShenandoahRetireGCLABClosure cl(false); 1091 1092 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) { 1093 ThreadLocalAllocBuffer& tlab = t->tlab(); 1094 tlab.make_parsable(); 1095 cl.do_thread(t); 1096 } 1097 1098 workers()->threads_do(&cl); 1099 } 1100 1101 void ShenandoahHeap::tlabs_retire(bool resize) { 1102 assert(UseTLAB, "Only call with UseTLAB"); 1103 assert(!resize || ResizeTLAB, "Only call for resize when ResizeTLAB is enabled"); 1104 1105 ThreadLocalAllocStats stats; 1106 1107 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) { 1108 ThreadLocalAllocBuffer& tlab = t->tlab(); 1109 tlab.retire(&stats); 1110 if (resize) { 1111 tlab.resize(); 1112 } 1113 } 1114 1115 stats.publish(); 1116 1117 #ifdef ASSERT 1118 ShenandoahCheckCleanGCLABClosure cl; 1119 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) { 1120 cl.do_thread(t); 1121 } 1122 workers()->threads_do(&cl); 1123 #endif 1124 } 1125 1126 void ShenandoahHeap::gclabs_retire(bool resize) { 1127 assert(UseTLAB, "Only call with UseTLAB"); 1128 assert(!resize || ResizeTLAB, "Only call for resize when ResizeTLAB is enabled"); 1129 1130 ShenandoahRetireGCLABClosure cl(resize); 1131 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) { 1132 cl.do_thread(t); 1133 } 1134 workers()->threads_do(&cl); 1135 1136 if (safepoint_workers() != NULL) { 1137 safepoint_workers()->threads_do(&cl); 1138 } 1139 } 1140 1141 // Returns size in bytes 1142 size_t ShenandoahHeap::unsafe_max_tlab_alloc(Thread *thread) const { 1143 if (ShenandoahElasticTLAB) { 1144 // With Elastic TLABs, return the max allowed size, and let the allocation path 1145 // figure out the safe size for current allocation. 1146 return ShenandoahHeapRegion::max_tlab_size_bytes(); 1147 } else { 1148 return MIN2(_free_set->unsafe_peek_free(), ShenandoahHeapRegion::max_tlab_size_bytes()); 1149 } 1150 } 1151 1152 size_t ShenandoahHeap::max_tlab_size() const { 1153 // Returns size in words 1154 return ShenandoahHeapRegion::max_tlab_size_words(); 1155 } 1156 1157 void ShenandoahHeap::collect(GCCause::Cause cause) { 1158 control_thread()->request_gc(cause); 1159 } 1160 1161 void ShenandoahHeap::do_full_collection(bool clear_all_soft_refs) { 1162 //assert(false, "Shouldn't need to do full collections"); 1163 } 1164 1165 HeapWord* ShenandoahHeap::block_start(const void* addr) const { 1166 ShenandoahHeapRegion* r = heap_region_containing(addr); 1167 if (r != NULL) { 1168 return r->block_start(addr); 1169 } 1170 return NULL; 1171 } 1172 1173 bool ShenandoahHeap::block_is_obj(const HeapWord* addr) const { 1174 ShenandoahHeapRegion* r = heap_region_containing(addr); 1175 return r->block_is_obj(addr); 1176 } 1177 1178 bool ShenandoahHeap::print_location(outputStream* st, void* addr) const { 1179 return BlockLocationPrinter<ShenandoahHeap>::print_location(st, addr); 1180 } 1181 1182 void ShenandoahHeap::prepare_for_verify() { 1183 if (SafepointSynchronize::is_at_safepoint() && UseTLAB) { 1184 labs_make_parsable(); 1185 } 1186 } 1187 1188 void ShenandoahHeap::gc_threads_do(ThreadClosure* tcl) const { 1189 tcl->do_thread(_control_thread); 1190 workers()->threads_do(tcl); 1191 if (_safepoint_workers != NULL) { 1192 _safepoint_workers->threads_do(tcl); 1193 } 1194 if (ShenandoahStringDedup::is_enabled()) { 1195 ShenandoahStringDedup::threads_do(tcl); 1196 } 1197 } 1198 1199 void ShenandoahHeap::print_tracing_info() const { 1200 LogTarget(Info, gc, stats) lt; 1201 if (lt.is_enabled()) { 1202 ResourceMark rm; 1203 LogStream ls(lt); 1204 1205 phase_timings()->print_global_on(&ls); 1206 1207 ls.cr(); 1208 ls.cr(); 1209 1210 shenandoah_policy()->print_gc_stats(&ls); 1211 1212 ls.cr(); 1213 ls.cr(); 1214 } 1215 } 1216 1217 void ShenandoahHeap::verify(VerifyOption vo) { 1218 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) { 1219 if (ShenandoahVerify) { 1220 verifier()->verify_generic(vo); 1221 } else { 1222 // TODO: Consider allocating verification bitmaps on demand, 1223 // and turn this on unconditionally. 1224 } 1225 } 1226 } 1227 size_t ShenandoahHeap::tlab_capacity(Thread *thr) const { 1228 return _free_set->capacity(); 1229 } 1230 1231 class ObjectIterateScanRootClosure : public BasicOopIterateClosure { 1232 private: 1233 MarkBitMap* _bitmap; 1234 ShenandoahScanObjectStack* _oop_stack; 1235 ShenandoahHeap* const _heap; 1236 ShenandoahMarkingContext* const _marking_context; 1237 1238 template <class T> 1239 void do_oop_work(T* p) { 1240 T o = RawAccess<>::oop_load(p); 1241 if (!CompressedOops::is_null(o)) { 1242 oop obj = CompressedOops::decode_not_null(o); 1243 if (_heap->is_concurrent_weak_root_in_progress() && !_marking_context->is_marked(obj)) { 1244 // There may be dead oops in weak roots in concurrent root phase, do not touch them. 1245 return; 1246 } 1247 obj = ShenandoahBarrierSet::barrier_set()->load_reference_barrier(obj); 1248 1249 assert(oopDesc::is_oop(obj), "must be a valid oop"); 1250 if (!_bitmap->is_marked(obj)) { 1251 _bitmap->mark(obj); 1252 _oop_stack->push(obj); 1253 } 1254 } 1255 } 1256 public: 1257 ObjectIterateScanRootClosure(MarkBitMap* bitmap, ShenandoahScanObjectStack* oop_stack) : 1258 _bitmap(bitmap), _oop_stack(oop_stack), _heap(ShenandoahHeap::heap()), 1259 _marking_context(_heap->marking_context()) {} 1260 void do_oop(oop* p) { do_oop_work(p); } 1261 void do_oop(narrowOop* p) { do_oop_work(p); } 1262 }; 1263 1264 /* 1265 * This is public API, used in preparation of object_iterate(). 1266 * Since we don't do linear scan of heap in object_iterate() (see comment below), we don't 1267 * need to make the heap parsable. For Shenandoah-internal linear heap scans that we can 1268 * control, we call SH::tlabs_retire, SH::gclabs_retire. 1269 */ 1270 void ShenandoahHeap::ensure_parsability(bool retire_tlabs) { 1271 // No-op. 1272 } 1273 1274 /* 1275 * Iterates objects in the heap. This is public API, used for, e.g., heap dumping. 1276 * 1277 * We cannot safely iterate objects by doing a linear scan at random points in time. Linear 1278 * scanning needs to deal with dead objects, which may have dead Klass* pointers (e.g. 1279 * calling oopDesc::size() would crash) or dangling reference fields (crashes) etc. Linear 1280 * scanning therefore depends on having a valid marking bitmap to support it. However, we only 1281 * have a valid marking bitmap after successful marking. In particular, we *don't* have a valid 1282 * marking bitmap during marking, after aborted marking or during/after cleanup (when we just 1283 * wiped the bitmap in preparation for next marking). 1284 * 1285 * For all those reasons, we implement object iteration as a single marking traversal, reporting 1286 * objects as we mark+traverse through the heap, starting from GC roots. JVMTI IterateThroughHeap 1287 * is allowed to report dead objects, but is not required to do so. 1288 */ 1289 void ShenandoahHeap::object_iterate(ObjectClosure* cl) { 1290 // Reset bitmap 1291 if (!prepare_aux_bitmap_for_iteration()) 1292 return; 1293 1294 ShenandoahScanObjectStack oop_stack; 1295 ObjectIterateScanRootClosure oops(&_aux_bit_map, &oop_stack); 1296 // Seed the stack with root scan 1297 scan_roots_for_iteration(&oop_stack, &oops); 1298 1299 // Work through the oop stack to traverse heap 1300 while (! oop_stack.is_empty()) { 1301 oop obj = oop_stack.pop(); 1302 assert(oopDesc::is_oop(obj), "must be a valid oop"); 1303 cl->do_object(obj); 1304 obj->oop_iterate(&oops); 1305 } 1306 1307 assert(oop_stack.is_empty(), "should be empty"); 1308 // Reclaim bitmap 1309 reclaim_aux_bitmap_for_iteration(); 1310 } 1311 1312 bool ShenandoahHeap::prepare_aux_bitmap_for_iteration() { 1313 assert(SafepointSynchronize::is_at_safepoint(), "safe iteration is only available during safepoints"); 1314 1315 if (!_aux_bitmap_region_special && !os::commit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size(), false)) { 1316 log_warning(gc)("Could not commit native memory for auxiliary marking bitmap for heap iteration"); 1317 return false; 1318 } 1319 // Reset bitmap 1320 _aux_bit_map.clear(); 1321 return true; 1322 } 1323 1324 void ShenandoahHeap::scan_roots_for_iteration(ShenandoahScanObjectStack* oop_stack, ObjectIterateScanRootClosure* oops) { 1325 // Process GC roots according to current GC cycle 1326 // This populates the work stack with initial objects 1327 // It is important to relinquish the associated locks before diving 1328 // into heap dumper 1329 ShenandoahHeapIterationRootScanner rp; 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!= NULL) { 1408 for (uint i = 0; i < _num_workers; ++i) { 1409 ShenandoahObjToScanQueue* q = _task_queues->queue(i); 1410 if (q != NULL) { 1411 delete q; 1412 _task_queues->register_queue(i, NULL); 1413 } 1414 } 1415 delete _task_queues; 1416 _task_queues = NULL; 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_queue->initialize(); 1434 _task_queues->register_queue(i, task_queue); 1435 } 1436 // Divide roots among the workers. Assume that object referencing distribution 1437 // is related with root kind, use round-robin to make every worker have same chance 1438 // to process every kind of roots 1439 size_t roots_num = _roots_stack.size(); 1440 if (roots_num == 0) { 1441 // No work to do 1442 return false; 1443 } 1444 1445 for (uint j = 0; j < roots_num; j++) { 1446 uint stack_id = j % _num_workers; 1447 oop obj = _roots_stack.pop(); 1448 _task_queues->queue(stack_id)->push(ShenandoahMarkTask(obj)); 1449 } 1450 return true; 1451 } 1452 1453 void object_iterate_parallel(ObjectClosure* cl, 1454 uint worker_id, 1455 ShenandoahObjToScanQueueSet* queue_set) { 1456 assert(SafepointSynchronize::is_at_safepoint(), "safe iteration is only available during safepoints"); 1457 assert(queue_set != NULL, "task queue must not be NULL"); 1458 1459 ShenandoahObjToScanQueue* q = queue_set->queue(worker_id); 1460 assert(q != NULL, "object iterate queue must not be NULL"); 1461 1462 ShenandoahMarkTask t; 1463 ShenandoahObjectIterateParScanClosure oops(_aux_bit_map, q); 1464 1465 // Work through the queue to traverse heap. 1466 // Steal when there is no task in queue. 1467 while (q->pop(t) || queue_set->steal(worker_id, t)) { 1468 oop obj = t.obj(); 1469 assert(oopDesc::is_oop(obj), "must be a valid oop"); 1470 cl->do_object(obj); 1471 obj->oop_iterate(&oops); 1472 } 1473 assert(q->is_empty(), "should be empty"); 1474 } 1475 }; 1476 1477 ParallelObjectIteratorImpl* ShenandoahHeap::parallel_object_iterator(uint workers) { 1478 return new ShenandoahParallelObjectIterator(workers, &_aux_bit_map); 1479 } 1480 1481 // Keep alive an object that was loaded with AS_NO_KEEPALIVE. 1482 void ShenandoahHeap::keep_alive(oop obj) { 1483 if (is_concurrent_mark_in_progress() && (obj != NULL)) { 1484 ShenandoahBarrierSet::barrier_set()->enqueue(obj); 1485 } 1486 } 1487 1488 void ShenandoahHeap::heap_region_iterate(ShenandoahHeapRegionClosure* blk) const { 1489 for (size_t i = 0; i < num_regions(); i++) { 1490 ShenandoahHeapRegion* current = get_region(i); 1491 blk->heap_region_do(current); 1492 } 1493 } 1494 1495 class ShenandoahParallelHeapRegionTask : public AbstractGangTask { 1496 private: 1497 ShenandoahHeap* const _heap; 1498 ShenandoahHeapRegionClosure* const _blk; 1499 1500 shenandoah_padding(0); 1501 volatile size_t _index; 1502 shenandoah_padding(1); 1503 1504 public: 1505 ShenandoahParallelHeapRegionTask(ShenandoahHeapRegionClosure* blk) : 1506 AbstractGangTask("Shenandoah Parallel Region Operation"), 1507 _heap(ShenandoahHeap::heap()), _blk(blk), _index(0) {} 1508 1509 void work(uint worker_id) { 1510 ShenandoahParallelWorkerSession worker_session(worker_id); 1511 size_t stride = ShenandoahParallelRegionStride; 1512 1513 size_t max = _heap->num_regions(); 1514 while (Atomic::load(&_index) < max) { 1515 size_t cur = Atomic::fetch_and_add(&_index, stride, memory_order_relaxed); 1516 size_t start = cur; 1517 size_t end = MIN2(cur + stride, max); 1518 if (start >= max) break; 1519 1520 for (size_t i = cur; i < end; i++) { 1521 ShenandoahHeapRegion* current = _heap->get_region(i); 1522 _blk->heap_region_do(current); 1523 } 1524 } 1525 } 1526 }; 1527 1528 void ShenandoahHeap::parallel_heap_region_iterate(ShenandoahHeapRegionClosure* blk) const { 1529 assert(blk->is_thread_safe(), "Only thread-safe closures here"); 1530 if (num_regions() > ShenandoahParallelRegionStride) { 1531 ShenandoahParallelHeapRegionTask task(blk); 1532 workers()->run_task(&task); 1533 } else { 1534 heap_region_iterate(blk); 1535 } 1536 } 1537 1538 class ShenandoahInitMarkUpdateRegionStateClosure : public ShenandoahHeapRegionClosure { 1539 private: 1540 ShenandoahMarkingContext* const _ctx; 1541 public: 1542 ShenandoahInitMarkUpdateRegionStateClosure() : _ctx(ShenandoahHeap::heap()->marking_context()) {} 1543 1544 void heap_region_do(ShenandoahHeapRegion* r) { 1545 assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->index()); 1546 if (r->is_active()) { 1547 // Check if region needs updating its TAMS. We have updated it already during concurrent 1548 // reset, so it is very likely we don't need to do another write here. 1549 if (_ctx->top_at_mark_start(r) != r->top()) { 1550 _ctx->capture_top_at_mark_start(r); 1551 } 1552 } else { 1553 assert(_ctx->top_at_mark_start(r) == r->top(), 1554 "Region " SIZE_FORMAT " should already have correct TAMS", r->index()); 1555 } 1556 } 1557 1558 bool is_thread_safe() { return true; } 1559 }; 1560 1561 class ShenandoahRendezvousClosure : public HandshakeClosure { 1562 public: 1563 inline ShenandoahRendezvousClosure() : HandshakeClosure("ShenandoahRendezvous") {} 1564 inline void do_thread(Thread* thread) {} 1565 }; 1566 1567 void ShenandoahHeap::rendezvous_threads() { 1568 ShenandoahRendezvousClosure cl; 1569 Handshake::execute(&cl); 1570 } 1571 1572 void ShenandoahHeap::recycle_trash() { 1573 free_set()->recycle_trash(); 1574 } 1575 1576 class ShenandoahResetUpdateRegionStateClosure : public ShenandoahHeapRegionClosure { 1577 private: 1578 ShenandoahMarkingContext* const _ctx; 1579 public: 1580 ShenandoahResetUpdateRegionStateClosure() : _ctx(ShenandoahHeap::heap()->marking_context()) {} 1581 1582 void heap_region_do(ShenandoahHeapRegion* r) { 1583 if (r->is_active()) { 1584 // Reset live data and set TAMS optimistically. We would recheck these under the pause 1585 // anyway to capture any updates that happened since now. 1586 r->clear_live_data(); 1587 _ctx->capture_top_at_mark_start(r); 1588 } 1589 } 1590 1591 bool is_thread_safe() { return true; } 1592 }; 1593 1594 void ShenandoahHeap::prepare_gc() { 1595 reset_mark_bitmap(); 1596 1597 ShenandoahResetUpdateRegionStateClosure cl; 1598 parallel_heap_region_iterate(&cl); 1599 } 1600 1601 class ShenandoahFinalMarkUpdateRegionStateClosure : public ShenandoahHeapRegionClosure { 1602 private: 1603 ShenandoahMarkingContext* const _ctx; 1604 ShenandoahHeapLock* const _lock; 1605 1606 public: 1607 ShenandoahFinalMarkUpdateRegionStateClosure() : 1608 _ctx(ShenandoahHeap::heap()->complete_marking_context()), _lock(ShenandoahHeap::heap()->lock()) {} 1609 1610 void heap_region_do(ShenandoahHeapRegion* r) { 1611 if (r->is_active()) { 1612 // All allocations past TAMS are implicitly live, adjust the region data. 1613 // Bitmaps/TAMS are swapped at this point, so we need to poll complete bitmap. 1614 HeapWord *tams = _ctx->top_at_mark_start(r); 1615 HeapWord *top = r->top(); 1616 if (top > tams) { 1617 r->increase_live_data_alloc_words(pointer_delta(top, tams)); 1618 } 1619 1620 // We are about to select the collection set, make sure it knows about 1621 // current pinning status. Also, this allows trashing more regions that 1622 // now have their pinning status dropped. 1623 if (r->is_pinned()) { 1624 if (r->pin_count() == 0) { 1625 ShenandoahHeapLocker locker(_lock); 1626 r->make_unpinned(); 1627 } 1628 } else { 1629 if (r->pin_count() > 0) { 1630 ShenandoahHeapLocker locker(_lock); 1631 r->make_pinned(); 1632 } 1633 } 1634 1635 // Remember limit for updating refs. It's guaranteed that we get no 1636 // from-space-refs written from here on. 1637 r->set_update_watermark_at_safepoint(r->top()); 1638 } else { 1639 assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->index()); 1640 assert(_ctx->top_at_mark_start(r) == r->top(), 1641 "Region " SIZE_FORMAT " should have correct TAMS", r->index()); 1642 } 1643 } 1644 1645 bool is_thread_safe() { return true; } 1646 }; 1647 1648 void ShenandoahHeap::prepare_regions_and_collection_set(bool concurrent) { 1649 assert(!is_full_gc_in_progress(), "Only for concurrent and degenerated GC"); 1650 { 1651 ShenandoahGCPhase phase(concurrent ? ShenandoahPhaseTimings::final_update_region_states : 1652 ShenandoahPhaseTimings::degen_gc_final_update_region_states); 1653 ShenandoahFinalMarkUpdateRegionStateClosure cl; 1654 parallel_heap_region_iterate(&cl); 1655 1656 assert_pinned_region_status(); 1657 } 1658 1659 { 1660 ShenandoahGCPhase phase(concurrent ? ShenandoahPhaseTimings::choose_cset : 1661 ShenandoahPhaseTimings::degen_gc_choose_cset); 1662 ShenandoahHeapLocker locker(lock()); 1663 _collection_set->clear(); 1664 heuristics()->choose_collection_set(_collection_set); 1665 } 1666 1667 { 1668 ShenandoahGCPhase phase(concurrent ? ShenandoahPhaseTimings::final_rebuild_freeset : 1669 ShenandoahPhaseTimings::degen_gc_final_rebuild_freeset); 1670 ShenandoahHeapLocker locker(lock()); 1671 _free_set->rebuild(); 1672 } 1673 } 1674 1675 void ShenandoahHeap::do_class_unloading() { 1676 _unloader.unload(); 1677 } 1678 1679 void ShenandoahHeap::stw_weak_refs(bool full_gc) { 1680 // Weak refs processing 1681 ShenandoahPhaseTimings::Phase phase = full_gc ? ShenandoahPhaseTimings::full_gc_weakrefs 1682 : ShenandoahPhaseTimings::degen_gc_weakrefs; 1683 ShenandoahTimingsTracker t(phase); 1684 ShenandoahGCWorkerPhase worker_phase(phase); 1685 ref_processor()->process_references(phase, workers(), false /* concurrent */); 1686 } 1687 1688 void ShenandoahHeap::prepare_update_heap_references(bool concurrent) { 1689 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint"); 1690 1691 // Evacuation is over, no GCLABs are needed anymore. GCLABs are under URWM, so we need to 1692 // make them parsable for update code to work correctly. Plus, we can compute new sizes 1693 // for future GCLABs here. 1694 if (UseTLAB) { 1695 ShenandoahGCPhase phase(concurrent ? 1696 ShenandoahPhaseTimings::init_update_refs_manage_gclabs : 1697 ShenandoahPhaseTimings::degen_gc_init_update_refs_manage_gclabs); 1698 gclabs_retire(ResizeTLAB); 1699 } 1700 1701 _update_refs_iterator.reset(); 1702 } 1703 1704 void ShenandoahHeap::set_gc_state_all_threads(char state) { 1705 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) { 1706 ShenandoahThreadLocalData::set_gc_state(t, state); 1707 } 1708 } 1709 1710 void ShenandoahHeap::set_gc_state_mask(uint mask, bool value) { 1711 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should really be Shenandoah safepoint"); 1712 _gc_state.set_cond(mask, value); 1713 set_gc_state_all_threads(_gc_state.raw_value()); 1714 } 1715 1716 void ShenandoahHeap::set_concurrent_mark_in_progress(bool in_progress) { 1717 assert(!has_forwarded_objects(), "Not expected before/after mark phase"); 1718 set_gc_state_mask(MARKING, in_progress); 1719 ShenandoahBarrierSet::satb_mark_queue_set().set_active_all_threads(in_progress, !in_progress); 1720 } 1721 1722 void ShenandoahHeap::set_evacuation_in_progress(bool in_progress) { 1723 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Only call this at safepoint"); 1724 set_gc_state_mask(EVACUATION, in_progress); 1725 } 1726 1727 void ShenandoahHeap::set_concurrent_strong_root_in_progress(bool in_progress) { 1728 if (in_progress) { 1729 _concurrent_strong_root_in_progress.set(); 1730 } else { 1731 _concurrent_strong_root_in_progress.unset(); 1732 } 1733 } 1734 1735 void ShenandoahHeap::set_concurrent_weak_root_in_progress(bool cond) { 1736 set_gc_state_mask(WEAK_ROOTS, cond); 1737 } 1738 1739 GCTracer* ShenandoahHeap::tracer() { 1740 return shenandoah_policy()->tracer(); 1741 } 1742 1743 size_t ShenandoahHeap::tlab_used(Thread* thread) const { 1744 return _free_set->used(); 1745 } 1746 1747 bool ShenandoahHeap::try_cancel_gc() { 1748 jbyte prev = _cancelled_gc.cmpxchg(CANCELLED, CANCELLABLE); 1749 return prev == CANCELLABLE; 1750 } 1751 1752 void ShenandoahHeap::cancel_gc(GCCause::Cause cause) { 1753 if (try_cancel_gc()) { 1754 FormatBuffer<> msg("Cancelling GC: %s", GCCause::to_string(cause)); 1755 log_info(gc)("%s", msg.buffer()); 1756 Events::log(Thread::current(), "%s", msg.buffer()); 1757 } 1758 } 1759 1760 uint ShenandoahHeap::max_workers() { 1761 return _max_workers; 1762 } 1763 1764 void ShenandoahHeap::stop() { 1765 // The shutdown sequence should be able to terminate when GC is running. 1766 1767 // Step 0. Notify policy to disable event recording. 1768 _shenandoah_policy->record_shutdown(); 1769 1770 // Step 1. Notify control thread that we are in shutdown. 1771 // Note that we cannot do that with stop(), because stop() is blocking and waits for the actual shutdown. 1772 // Doing stop() here would wait for the normal GC cycle to complete, never falling through to cancel below. 1773 control_thread()->prepare_for_graceful_shutdown(); 1774 1775 // Step 2. Notify GC workers that we are cancelling GC. 1776 cancel_gc(GCCause::_shenandoah_stop_vm); 1777 1778 // Step 3. Wait until GC worker exits normally. 1779 control_thread()->stop(); 1780 } 1781 1782 void ShenandoahHeap::stw_unload_classes(bool full_gc) { 1783 if (!unload_classes()) return; 1784 // Unload classes and purge SystemDictionary. 1785 { 1786 ShenandoahPhaseTimings::Phase phase = full_gc ? 1787 ShenandoahPhaseTimings::full_gc_purge_class_unload : 1788 ShenandoahPhaseTimings::degen_gc_purge_class_unload; 1789 ShenandoahGCPhase gc_phase(phase); 1790 ShenandoahGCWorkerPhase worker_phase(phase); 1791 bool purged_class = SystemDictionary::do_unloading(gc_timer()); 1792 1793 ShenandoahIsAliveSelector is_alive; 1794 uint num_workers = _workers->active_workers(); 1795 ShenandoahClassUnloadingTask unlink_task(phase, is_alive.is_alive_closure(), num_workers, purged_class); 1796 _workers->run_task(&unlink_task); 1797 } 1798 1799 { 1800 ShenandoahGCPhase phase(full_gc ? 1801 ShenandoahPhaseTimings::full_gc_purge_cldg : 1802 ShenandoahPhaseTimings::degen_gc_purge_cldg); 1803 ClassLoaderDataGraph::purge(/*at_safepoint*/true); 1804 } 1805 // Resize and verify metaspace 1806 MetaspaceGC::compute_new_size(); 1807 DEBUG_ONLY(MetaspaceUtils::verify();) 1808 } 1809 1810 // Weak roots are either pre-evacuated (final mark) or updated (final updaterefs), 1811 // so they should not have forwarded oops. 1812 // However, we do need to "null" dead oops in the roots, if can not be done 1813 // in concurrent cycles. 1814 void ShenandoahHeap::stw_process_weak_roots(bool full_gc) { 1815 uint num_workers = _workers->active_workers(); 1816 ShenandoahPhaseTimings::Phase timing_phase = full_gc ? 1817 ShenandoahPhaseTimings::full_gc_purge_weak_par : 1818 ShenandoahPhaseTimings::degen_gc_purge_weak_par; 1819 ShenandoahGCPhase phase(timing_phase); 1820 ShenandoahGCWorkerPhase worker_phase(timing_phase); 1821 // Cleanup weak roots 1822 if (has_forwarded_objects()) { 1823 ShenandoahForwardedIsAliveClosure is_alive; 1824 ShenandoahUpdateRefsClosure keep_alive; 1825 ShenandoahParallelWeakRootsCleaningTask<ShenandoahForwardedIsAliveClosure, ShenandoahUpdateRefsClosure> 1826 cleaning_task(timing_phase, &is_alive, &keep_alive, num_workers); 1827 _workers->run_task(&cleaning_task); 1828 } else { 1829 ShenandoahIsAliveClosure is_alive; 1830 #ifdef ASSERT 1831 ShenandoahAssertNotForwardedClosure verify_cl; 1832 ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, ShenandoahAssertNotForwardedClosure> 1833 cleaning_task(timing_phase, &is_alive, &verify_cl, num_workers); 1834 #else 1835 ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, DoNothingClosure> 1836 cleaning_task(timing_phase, &is_alive, &do_nothing_cl, num_workers); 1837 #endif 1838 _workers->run_task(&cleaning_task); 1839 } 1840 } 1841 1842 void ShenandoahHeap::parallel_cleaning(bool full_gc) { 1843 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint"); 1844 assert(is_stw_gc_in_progress(), "Only for Degenerated and Full GC"); 1845 ShenandoahGCPhase phase(full_gc ? 1846 ShenandoahPhaseTimings::full_gc_purge : 1847 ShenandoahPhaseTimings::degen_gc_purge); 1848 stw_weak_refs(full_gc); 1849 stw_process_weak_roots(full_gc); 1850 stw_unload_classes(full_gc); 1851 } 1852 1853 void ShenandoahHeap::set_has_forwarded_objects(bool cond) { 1854 set_gc_state_mask(HAS_FORWARDED, cond); 1855 } 1856 1857 void ShenandoahHeap::set_unload_classes(bool uc) { 1858 _unload_classes.set_cond(uc); 1859 } 1860 1861 bool ShenandoahHeap::unload_classes() const { 1862 return _unload_classes.is_set(); 1863 } 1864 1865 address ShenandoahHeap::in_cset_fast_test_addr() { 1866 ShenandoahHeap* heap = ShenandoahHeap::heap(); 1867 assert(heap->collection_set() != NULL, "Sanity"); 1868 return (address) heap->collection_set()->biased_map_address(); 1869 } 1870 1871 address ShenandoahHeap::cancelled_gc_addr() { 1872 return (address) ShenandoahHeap::heap()->_cancelled_gc.addr_of(); 1873 } 1874 1875 address ShenandoahHeap::gc_state_addr() { 1876 return (address) ShenandoahHeap::heap()->_gc_state.addr_of(); 1877 } 1878 1879 size_t ShenandoahHeap::bytes_allocated_since_gc_start() { 1880 return Atomic::load(&_bytes_allocated_since_gc_start); 1881 } 1882 1883 void ShenandoahHeap::reset_bytes_allocated_since_gc_start() { 1884 Atomic::store(&_bytes_allocated_since_gc_start, (size_t)0); 1885 } 1886 1887 void ShenandoahHeap::set_degenerated_gc_in_progress(bool in_progress) { 1888 _degenerated_gc_in_progress.set_cond(in_progress); 1889 } 1890 1891 void ShenandoahHeap::set_full_gc_in_progress(bool in_progress) { 1892 _full_gc_in_progress.set_cond(in_progress); 1893 } 1894 1895 void ShenandoahHeap::set_full_gc_move_in_progress(bool in_progress) { 1896 assert (is_full_gc_in_progress(), "should be"); 1897 _full_gc_move_in_progress.set_cond(in_progress); 1898 } 1899 1900 void ShenandoahHeap::set_update_refs_in_progress(bool in_progress) { 1901 set_gc_state_mask(UPDATEREFS, in_progress); 1902 } 1903 1904 void ShenandoahHeap::register_nmethod(nmethod* nm) { 1905 ShenandoahCodeRoots::register_nmethod(nm); 1906 } 1907 1908 void ShenandoahHeap::unregister_nmethod(nmethod* nm) { 1909 ShenandoahCodeRoots::unregister_nmethod(nm); 1910 } 1911 1912 void ShenandoahHeap::flush_nmethod(nmethod* nm) { 1913 ShenandoahCodeRoots::flush_nmethod(nm); 1914 } 1915 1916 oop ShenandoahHeap::pin_object(JavaThread* thr, oop o) { 1917 heap_region_containing(o)->record_pin(); 1918 return o; 1919 } 1920 1921 void ShenandoahHeap::unpin_object(JavaThread* thr, oop o) { 1922 ShenandoahHeapRegion* r = heap_region_containing(o); 1923 assert(r != NULL, "Sanity"); 1924 assert(r->pin_count() > 0, "Region " SIZE_FORMAT " should have non-zero pins", r->index()); 1925 r->record_unpin(); 1926 } 1927 1928 void ShenandoahHeap::sync_pinned_region_status() { 1929 ShenandoahHeapLocker locker(lock()); 1930 1931 for (size_t i = 0; i < num_regions(); i++) { 1932 ShenandoahHeapRegion *r = get_region(i); 1933 if (r->is_active()) { 1934 if (r->is_pinned()) { 1935 if (r->pin_count() == 0) { 1936 r->make_unpinned(); 1937 } 1938 } else { 1939 if (r->pin_count() > 0) { 1940 r->make_pinned(); 1941 } 1942 } 1943 } 1944 } 1945 1946 assert_pinned_region_status(); 1947 } 1948 1949 #ifdef ASSERT 1950 void ShenandoahHeap::assert_pinned_region_status() { 1951 for (size_t i = 0; i < num_regions(); i++) { 1952 ShenandoahHeapRegion* r = get_region(i); 1953 assert((r->is_pinned() && r->pin_count() > 0) || (!r->is_pinned() && r->pin_count() == 0), 1954 "Region " SIZE_FORMAT " pinning status is inconsistent", i); 1955 } 1956 } 1957 #endif 1958 1959 ConcurrentGCTimer* ShenandoahHeap::gc_timer() const { 1960 return _gc_timer; 1961 } 1962 1963 void ShenandoahHeap::prepare_concurrent_roots() { 1964 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint"); 1965 assert(!is_stw_gc_in_progress(), "Only concurrent GC"); 1966 set_concurrent_strong_root_in_progress(!collection_set()->is_empty()); 1967 set_concurrent_weak_root_in_progress(true); 1968 if (unload_classes()) { 1969 _unloader.prepare(); 1970 } 1971 } 1972 1973 void ShenandoahHeap::finish_concurrent_roots() { 1974 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint"); 1975 assert(!is_stw_gc_in_progress(), "Only concurrent GC"); 1976 if (unload_classes()) { 1977 _unloader.finish(); 1978 } 1979 } 1980 1981 #ifdef ASSERT 1982 void ShenandoahHeap::assert_gc_workers(uint nworkers) { 1983 assert(nworkers > 0 && nworkers <= max_workers(), "Sanity"); 1984 1985 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) { 1986 if (UseDynamicNumberOfGCThreads) { 1987 assert(nworkers <= ParallelGCThreads, "Cannot use more than it has"); 1988 } else { 1989 // Use ParallelGCThreads inside safepoints 1990 assert(nworkers == ParallelGCThreads, "Use ParallelGCThreads within safepoints"); 1991 } 1992 } else { 1993 if (UseDynamicNumberOfGCThreads) { 1994 assert(nworkers <= ConcGCThreads, "Cannot use more than it has"); 1995 } else { 1996 // Use ConcGCThreads outside safepoints 1997 assert(nworkers == ConcGCThreads, "Use ConcGCThreads outside safepoints"); 1998 } 1999 } 2000 } 2001 #endif 2002 2003 ShenandoahVerifier* ShenandoahHeap::verifier() { 2004 guarantee(ShenandoahVerify, "Should be enabled"); 2005 assert (_verifier != NULL, "sanity"); 2006 return _verifier; 2007 } 2008 2009 template<bool CONCURRENT> 2010 class ShenandoahUpdateHeapRefsTask : public AbstractGangTask { 2011 private: 2012 ShenandoahHeap* _heap; 2013 ShenandoahRegionIterator* _regions; 2014 public: 2015 ShenandoahUpdateHeapRefsTask(ShenandoahRegionIterator* regions) : 2016 AbstractGangTask("Shenandoah Update References"), 2017 _heap(ShenandoahHeap::heap()), 2018 _regions(regions) { 2019 } 2020 2021 void work(uint worker_id) { 2022 if (CONCURRENT) { 2023 ShenandoahConcurrentWorkerSession worker_session(worker_id); 2024 ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers); 2025 do_work<ShenandoahConcUpdateRefsClosure>(); 2026 } else { 2027 ShenandoahParallelWorkerSession worker_session(worker_id); 2028 do_work<ShenandoahSTWUpdateRefsClosure>(); 2029 } 2030 } 2031 2032 private: 2033 template<class T> 2034 void do_work() { 2035 T cl; 2036 ShenandoahHeapRegion* r = _regions->next(); 2037 ShenandoahMarkingContext* const ctx = _heap->complete_marking_context(); 2038 while (r != NULL) { 2039 HeapWord* update_watermark = r->get_update_watermark(); 2040 assert (update_watermark >= r->bottom(), "sanity"); 2041 if (r->is_active() && !r->is_cset()) { 2042 _heap->marked_object_oop_iterate(r, &cl, update_watermark); 2043 } 2044 if (ShenandoahPacing) { 2045 _heap->pacer()->report_updaterefs(pointer_delta(update_watermark, r->bottom())); 2046 } 2047 if (_heap->check_cancelled_gc_and_yield(CONCURRENT)) { 2048 return; 2049 } 2050 r = _regions->next(); 2051 } 2052 } 2053 }; 2054 2055 void ShenandoahHeap::update_heap_references(bool concurrent) { 2056 assert(!is_full_gc_in_progress(), "Only for concurrent and degenerated GC"); 2057 2058 if (concurrent) { 2059 ShenandoahUpdateHeapRefsTask<true> task(&_update_refs_iterator); 2060 workers()->run_task(&task); 2061 } else { 2062 ShenandoahUpdateHeapRefsTask<false> task(&_update_refs_iterator); 2063 workers()->run_task(&task); 2064 } 2065 } 2066 2067 2068 class ShenandoahFinalUpdateRefsUpdateRegionStateClosure : public ShenandoahHeapRegionClosure { 2069 private: 2070 ShenandoahHeapLock* const _lock; 2071 2072 public: 2073 ShenandoahFinalUpdateRefsUpdateRegionStateClosure() : _lock(ShenandoahHeap::heap()->lock()) {} 2074 2075 void heap_region_do(ShenandoahHeapRegion* r) { 2076 // Drop unnecessary "pinned" state from regions that does not have CP marks 2077 // anymore, as this would allow trashing them. 2078 2079 if (r->is_active()) { 2080 if (r->is_pinned()) { 2081 if (r->pin_count() == 0) { 2082 ShenandoahHeapLocker locker(_lock); 2083 r->make_unpinned(); 2084 } 2085 } else { 2086 if (r->pin_count() > 0) { 2087 ShenandoahHeapLocker locker(_lock); 2088 r->make_pinned(); 2089 } 2090 } 2091 } 2092 } 2093 2094 bool is_thread_safe() { return true; } 2095 }; 2096 2097 void ShenandoahHeap::update_heap_region_states(bool concurrent) { 2098 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint"); 2099 assert(!is_full_gc_in_progress(), "Only for concurrent and degenerated GC"); 2100 2101 { 2102 ShenandoahGCPhase phase(concurrent ? 2103 ShenandoahPhaseTimings::final_update_refs_update_region_states : 2104 ShenandoahPhaseTimings::degen_gc_final_update_refs_update_region_states); 2105 ShenandoahFinalUpdateRefsUpdateRegionStateClosure cl; 2106 parallel_heap_region_iterate(&cl); 2107 2108 assert_pinned_region_status(); 2109 } 2110 2111 { 2112 ShenandoahGCPhase phase(concurrent ? 2113 ShenandoahPhaseTimings::final_update_refs_trash_cset : 2114 ShenandoahPhaseTimings::degen_gc_final_update_refs_trash_cset); 2115 trash_cset_regions(); 2116 } 2117 } 2118 2119 void ShenandoahHeap::rebuild_free_set(bool concurrent) { 2120 { 2121 ShenandoahGCPhase phase(concurrent ? 2122 ShenandoahPhaseTimings::final_update_refs_rebuild_freeset : 2123 ShenandoahPhaseTimings::degen_gc_final_update_refs_rebuild_freeset); 2124 ShenandoahHeapLocker locker(lock()); 2125 _free_set->rebuild(); 2126 } 2127 } 2128 2129 void ShenandoahHeap::print_extended_on(outputStream *st) const { 2130 print_on(st); 2131 st->cr(); 2132 print_heap_regions_on(st); 2133 } 2134 2135 bool ShenandoahHeap::is_bitmap_slice_committed(ShenandoahHeapRegion* r, bool skip_self) { 2136 size_t slice = r->index() / _bitmap_regions_per_slice; 2137 2138 size_t regions_from = _bitmap_regions_per_slice * slice; 2139 size_t regions_to = MIN2(num_regions(), _bitmap_regions_per_slice * (slice + 1)); 2140 for (size_t g = regions_from; g < regions_to; g++) { 2141 assert (g / _bitmap_regions_per_slice == slice, "same slice"); 2142 if (skip_self && g == r->index()) continue; 2143 if (get_region(g)->is_committed()) { 2144 return true; 2145 } 2146 } 2147 return false; 2148 } 2149 2150 bool ShenandoahHeap::commit_bitmap_slice(ShenandoahHeapRegion* r) { 2151 shenandoah_assert_heaplocked(); 2152 2153 // Bitmaps in special regions do not need commits 2154 if (_bitmap_region_special) { 2155 return true; 2156 } 2157 2158 if (is_bitmap_slice_committed(r, true)) { 2159 // Some other region from the group is already committed, meaning the bitmap 2160 // slice is already committed, we exit right away. 2161 return true; 2162 } 2163 2164 // Commit the bitmap slice: 2165 size_t slice = r->index() / _bitmap_regions_per_slice; 2166 size_t off = _bitmap_bytes_per_slice * slice; 2167 size_t len = _bitmap_bytes_per_slice; 2168 char* start = (char*) _bitmap_region.start() + off; 2169 2170 if (!os::commit_memory(start, len, false)) { 2171 return false; 2172 } 2173 2174 if (AlwaysPreTouch) { 2175 os::pretouch_memory(start, start + len, _pretouch_bitmap_page_size); 2176 } 2177 2178 return true; 2179 } 2180 2181 bool ShenandoahHeap::uncommit_bitmap_slice(ShenandoahHeapRegion *r) { 2182 shenandoah_assert_heaplocked(); 2183 2184 // Bitmaps in special regions do not need uncommits 2185 if (_bitmap_region_special) { 2186 return true; 2187 } 2188 2189 if (is_bitmap_slice_committed(r, true)) { 2190 // Some other region from the group is still committed, meaning the bitmap 2191 // slice is should stay committed, exit right away. 2192 return true; 2193 } 2194 2195 // Uncommit the bitmap slice: 2196 size_t slice = r->index() / _bitmap_regions_per_slice; 2197 size_t off = _bitmap_bytes_per_slice * slice; 2198 size_t len = _bitmap_bytes_per_slice; 2199 if (!os::uncommit_memory((char*)_bitmap_region.start() + off, len)) { 2200 return false; 2201 } 2202 return true; 2203 } 2204 2205 void ShenandoahHeap::safepoint_synchronize_begin() { 2206 if (ShenandoahSuspendibleWorkers || UseStringDeduplication) { 2207 SuspendibleThreadSet::synchronize(); 2208 } 2209 } 2210 2211 void ShenandoahHeap::safepoint_synchronize_end() { 2212 if (ShenandoahSuspendibleWorkers || UseStringDeduplication) { 2213 SuspendibleThreadSet::desynchronize(); 2214 } 2215 } 2216 2217 void ShenandoahHeap::entry_uncommit(double shrink_before, size_t shrink_until) { 2218 static const char *msg = "Concurrent uncommit"; 2219 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_uncommit, true /* log_heap_usage */); 2220 EventMark em("%s", msg); 2221 2222 op_uncommit(shrink_before, shrink_until); 2223 } 2224 2225 void ShenandoahHeap::try_inject_alloc_failure() { 2226 if (ShenandoahAllocFailureALot && !cancelled_gc() && ((os::random() % 1000) > 950)) { 2227 _inject_alloc_failure.set(); 2228 os::naked_short_sleep(1); 2229 if (cancelled_gc()) { 2230 log_info(gc)("Allocation failure was successfully injected"); 2231 } 2232 } 2233 } 2234 2235 bool ShenandoahHeap::should_inject_alloc_failure() { 2236 return _inject_alloc_failure.is_set() && _inject_alloc_failure.try_unset(); 2237 } 2238 2239 void ShenandoahHeap::initialize_serviceability() { 2240 _memory_pool = new ShenandoahMemoryPool(this); 2241 _cycle_memory_manager.add_pool(_memory_pool); 2242 _stw_memory_manager.add_pool(_memory_pool); 2243 } 2244 2245 GrowableArray<GCMemoryManager*> ShenandoahHeap::memory_managers() { 2246 GrowableArray<GCMemoryManager*> memory_managers(2); 2247 memory_managers.append(&_cycle_memory_manager); 2248 memory_managers.append(&_stw_memory_manager); 2249 return memory_managers; 2250 } 2251 2252 GrowableArray<MemoryPool*> ShenandoahHeap::memory_pools() { 2253 GrowableArray<MemoryPool*> memory_pools(1); 2254 memory_pools.append(_memory_pool); 2255 return memory_pools; 2256 } 2257 2258 MemoryUsage ShenandoahHeap::memory_usage() { 2259 return _memory_pool->get_memory_usage(); 2260 } 2261 2262 ShenandoahRegionIterator::ShenandoahRegionIterator() : 2263 _heap(ShenandoahHeap::heap()), 2264 _index(0) {} 2265 2266 ShenandoahRegionIterator::ShenandoahRegionIterator(ShenandoahHeap* heap) : 2267 _heap(heap), 2268 _index(0) {} 2269 2270 void ShenandoahRegionIterator::reset() { 2271 _index = 0; 2272 } 2273 2274 bool ShenandoahRegionIterator::has_next() const { 2275 return _index < _heap->num_regions(); 2276 } 2277 2278 char ShenandoahHeap::gc_state() const { 2279 return _gc_state.raw_value(); 2280 } 2281 2282 ShenandoahLiveData* ShenandoahHeap::get_liveness_cache(uint worker_id) { 2283 #ifdef ASSERT 2284 assert(_liveness_cache != NULL, "sanity"); 2285 assert(worker_id < _max_workers, "sanity"); 2286 for (uint i = 0; i < num_regions(); i++) { 2287 assert(_liveness_cache[worker_id][i] == 0, "liveness cache should be empty"); 2288 } 2289 #endif 2290 return _liveness_cache[worker_id]; 2291 } 2292 2293 void ShenandoahHeap::flush_liveness_cache(uint worker_id) { 2294 assert(worker_id < _max_workers, "sanity"); 2295 assert(_liveness_cache != NULL, "sanity"); 2296 ShenandoahLiveData* ld = _liveness_cache[worker_id]; 2297 for (uint i = 0; i < num_regions(); i++) { 2298 ShenandoahLiveData live = ld[i]; 2299 if (live > 0) { 2300 ShenandoahHeapRegion* r = get_region(i); 2301 r->increase_live_data_gc_words(live); 2302 ld[i] = 0; 2303 } 2304 } 2305 }