1 /* 2 * Copyright (c) 2023, 2025, Oracle and/or its affiliates. All rights reserved. 3 * Copyright (c) 2013, 2022, Red Hat, Inc. All rights reserved. 4 * Copyright Amazon.com Inc. or its affiliates. All Rights Reserved. 5 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 6 * 7 * This code is free software; you can redistribute it and/or modify it 8 * under the terms of the GNU General Public License version 2 only, as 9 * published by the Free Software Foundation. 10 * 11 * This code is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 * 25 */ 26 27 28 #include "cds/archiveHeapWriter.hpp" 29 #include "classfile/systemDictionary.hpp" 30 #include "gc/shared/classUnloadingContext.hpp" 31 #include "gc/shared/fullGCForwarding.hpp" 32 #include "gc/shared/gcArguments.hpp" 33 #include "gc/shared/gcTimer.hpp" 34 #include "gc/shared/gcTraceTime.inline.hpp" 35 #include "gc/shared/locationPrinter.inline.hpp" 36 #include "gc/shared/memAllocator.hpp" 37 #include "gc/shared/plab.hpp" 38 #include "gc/shared/tlab_globals.hpp" 39 #include "gc/shenandoah/heuristics/shenandoahOldHeuristics.hpp" 40 #include "gc/shenandoah/heuristics/shenandoahYoungHeuristics.hpp" 41 #include "gc/shenandoah/mode/shenandoahGenerationalMode.hpp" 42 #include "gc/shenandoah/mode/shenandoahPassiveMode.hpp" 43 #include "gc/shenandoah/mode/shenandoahSATBMode.hpp" 44 #include "gc/shenandoah/shenandoahAllocRequest.hpp" 45 #include "gc/shenandoah/shenandoahBarrierSet.hpp" 46 #include "gc/shenandoah/shenandoahClosures.inline.hpp" 47 #include "gc/shenandoah/shenandoahCodeRoots.hpp" 48 #include "gc/shenandoah/shenandoahCollectionSet.hpp" 49 #include "gc/shenandoah/shenandoahCollectorPolicy.hpp" 50 #include "gc/shenandoah/shenandoahConcurrentMark.hpp" 51 #include "gc/shenandoah/shenandoahControlThread.hpp" 52 #include "gc/shenandoah/shenandoahFreeSet.hpp" 53 #include "gc/shenandoah/shenandoahGenerationalEvacuationTask.hpp" 54 #include "gc/shenandoah/shenandoahGenerationalHeap.hpp" 55 #include "gc/shenandoah/shenandoahGlobalGeneration.hpp" 56 #include "gc/shenandoah/shenandoahHeap.inline.hpp" 57 #include "gc/shenandoah/shenandoahHeapRegion.inline.hpp" 58 #include "gc/shenandoah/shenandoahHeapRegionClosures.hpp" 59 #include "gc/shenandoah/shenandoahHeapRegionSet.hpp" 60 #include "gc/shenandoah/shenandoahInitLogger.hpp" 61 #include "gc/shenandoah/shenandoahMarkingContext.inline.hpp" 62 #include "gc/shenandoah/shenandoahMemoryPool.hpp" 63 #include "gc/shenandoah/shenandoahMonitoringSupport.hpp" 64 #include "gc/shenandoah/shenandoahOldGeneration.hpp" 65 #include "gc/shenandoah/shenandoahPacer.inline.hpp" 66 #include "gc/shenandoah/shenandoahPadding.hpp" 67 #include "gc/shenandoah/shenandoahParallelCleaning.inline.hpp" 68 #include "gc/shenandoah/shenandoahPhaseTimings.hpp" 69 #include "gc/shenandoah/shenandoahReferenceProcessor.hpp" 70 #include "gc/shenandoah/shenandoahRootProcessor.inline.hpp" 71 #include "gc/shenandoah/shenandoahScanRemembered.inline.hpp" 72 #include "gc/shenandoah/shenandoahSTWMark.hpp" 73 #include "gc/shenandoah/shenandoahUncommitThread.hpp" 74 #include "gc/shenandoah/shenandoahUtils.hpp" 75 #include "gc/shenandoah/shenandoahVerifier.hpp" 76 #include "gc/shenandoah/shenandoahVMOperations.hpp" 77 #include "gc/shenandoah/shenandoahWorkerPolicy.hpp" 78 #include "gc/shenandoah/shenandoahWorkGroup.hpp" 79 #include "gc/shenandoah/shenandoahYoungGeneration.hpp" 80 #include "memory/allocation.hpp" 81 #include "memory/classLoaderMetaspace.hpp" 82 #include "memory/memoryReserver.hpp" 83 #include "memory/metaspaceUtils.hpp" 84 #include "memory/universe.hpp" 85 #include "nmt/mallocTracker.hpp" 86 #include "nmt/memTracker.hpp" 87 #include "oops/compressedOops.inline.hpp" 88 #include "prims/jvmtiTagMap.hpp" 89 #include "runtime/atomic.hpp" 90 #include "runtime/globals.hpp" 91 #include "runtime/interfaceSupport.inline.hpp" 92 #include "runtime/java.hpp" 93 #include "runtime/orderAccess.hpp" 94 #include "runtime/safepointMechanism.hpp" 95 #include "runtime/stackWatermarkSet.hpp" 96 #include "runtime/threads.hpp" 97 #include "runtime/vmThread.hpp" 98 #include "utilities/events.hpp" 99 #include "utilities/globalDefinitions.hpp" 100 #include "utilities/powerOfTwo.hpp" 101 #if INCLUDE_JVMCI 102 #include "jvmci/jvmci.hpp" 103 #endif 104 #if INCLUDE_JFR 105 #include "gc/shenandoah/shenandoahJfrSupport.hpp" 106 #endif 107 108 class ShenandoahPretouchHeapTask : public WorkerTask { 109 private: 110 ShenandoahRegionIterator _regions; 111 const size_t _page_size; 112 public: 113 ShenandoahPretouchHeapTask(size_t page_size) : 114 WorkerTask("Shenandoah Pretouch Heap"), 115 _page_size(page_size) {} 116 117 virtual void work(uint worker_id) { 118 ShenandoahHeapRegion* r = _regions.next(); 119 while (r != nullptr) { 120 if (r->is_committed()) { 121 os::pretouch_memory(r->bottom(), r->end(), _page_size); 122 } 123 r = _regions.next(); 124 } 125 } 126 }; 127 128 class ShenandoahPretouchBitmapTask : public WorkerTask { 129 private: 130 ShenandoahRegionIterator _regions; 131 char* _bitmap_base; 132 const size_t _bitmap_size; 133 const size_t _page_size; 134 public: 135 ShenandoahPretouchBitmapTask(char* bitmap_base, size_t bitmap_size, size_t page_size) : 136 WorkerTask("Shenandoah Pretouch Bitmap"), 137 _bitmap_base(bitmap_base), 138 _bitmap_size(bitmap_size), 139 _page_size(page_size) {} 140 141 virtual void work(uint worker_id) { 142 ShenandoahHeapRegion* r = _regions.next(); 143 while (r != nullptr) { 144 size_t start = r->index() * ShenandoahHeapRegion::region_size_bytes() / MarkBitMap::heap_map_factor(); 145 size_t end = (r->index() + 1) * ShenandoahHeapRegion::region_size_bytes() / MarkBitMap::heap_map_factor(); 146 assert (end <= _bitmap_size, "end is sane: %zu < %zu", end, _bitmap_size); 147 148 if (r->is_committed()) { 149 os::pretouch_memory(_bitmap_base + start, _bitmap_base + end, _page_size); 150 } 151 152 r = _regions.next(); 153 } 154 } 155 }; 156 157 static ReservedSpace reserve(size_t size, size_t preferred_page_size) { 158 // When a page size is given we don't want to mix large 159 // and normal pages. If the size is not a multiple of the 160 // page size it will be aligned up to achieve this. 161 size_t alignment = os::vm_allocation_granularity(); 162 if (preferred_page_size != os::vm_page_size()) { 163 alignment = MAX2(preferred_page_size, alignment); 164 size = align_up(size, alignment); 165 } 166 167 const ReservedSpace reserved = MemoryReserver::reserve(size, alignment, preferred_page_size, mtGC); 168 if (!reserved.is_reserved()) { 169 vm_exit_during_initialization("Could not reserve space"); 170 } 171 return reserved; 172 } 173 174 jint ShenandoahHeap::initialize() { 175 // 176 // Figure out heap sizing 177 // 178 179 size_t init_byte_size = InitialHeapSize; 180 size_t min_byte_size = MinHeapSize; 181 size_t max_byte_size = MaxHeapSize; 182 size_t heap_alignment = HeapAlignment; 183 184 size_t reg_size_bytes = ShenandoahHeapRegion::region_size_bytes(); 185 186 Universe::check_alignment(max_byte_size, reg_size_bytes, "Shenandoah heap"); 187 Universe::check_alignment(init_byte_size, reg_size_bytes, "Shenandoah heap"); 188 189 _num_regions = ShenandoahHeapRegion::region_count(); 190 assert(_num_regions == (max_byte_size / reg_size_bytes), 191 "Regions should cover entire heap exactly: %zu != %zu/%zu", 192 _num_regions, max_byte_size, reg_size_bytes); 193 194 size_t num_committed_regions = init_byte_size / reg_size_bytes; 195 num_committed_regions = MIN2(num_committed_regions, _num_regions); 196 assert(num_committed_regions <= _num_regions, "sanity"); 197 _initial_size = num_committed_regions * reg_size_bytes; 198 199 size_t num_min_regions = min_byte_size / reg_size_bytes; 200 num_min_regions = MIN2(num_min_regions, _num_regions); 201 assert(num_min_regions <= _num_regions, "sanity"); 202 _minimum_size = num_min_regions * reg_size_bytes; 203 204 // Default to max heap size. 205 _soft_max_size = _num_regions * reg_size_bytes; 206 207 _committed = _initial_size; 208 209 size_t heap_page_size = UseLargePages ? os::large_page_size() : os::vm_page_size(); 210 size_t bitmap_page_size = UseLargePages ? os::large_page_size() : os::vm_page_size(); 211 size_t region_page_size = UseLargePages ? os::large_page_size() : os::vm_page_size(); 212 213 // 214 // Reserve and commit memory for heap 215 // 216 217 ReservedHeapSpace heap_rs = Universe::reserve_heap(max_byte_size, heap_alignment); 218 initialize_reserved_region(heap_rs); 219 _heap_region = MemRegion((HeapWord*)heap_rs.base(), heap_rs.size() / HeapWordSize); 220 _heap_region_special = heap_rs.special(); 221 222 assert((((size_t) base()) & ShenandoahHeapRegion::region_size_bytes_mask()) == 0, 223 "Misaligned heap: " PTR_FORMAT, p2i(base())); 224 os::trace_page_sizes_for_requested_size("Heap", 225 max_byte_size, heap_alignment, 226 heap_rs.base(), 227 heap_rs.size(), heap_rs.page_size()); 228 229 #if SHENANDOAH_OPTIMIZED_MARKTASK 230 // The optimized ShenandoahMarkTask takes some bits away from the full object bits. 231 // Fail if we ever attempt to address more than we can. 232 if ((uintptr_t)heap_rs.end() >= ShenandoahMarkTask::max_addressable()) { 233 FormatBuffer<512> buf("Shenandoah reserved [" PTR_FORMAT ", " PTR_FORMAT") for the heap, \n" 234 "but max object address is " PTR_FORMAT ". Try to reduce heap size, or try other \n" 235 "VM options that allocate heap at lower addresses (HeapBaseMinAddress, AllocateHeapAt, etc).", 236 p2i(heap_rs.base()), p2i(heap_rs.end()), ShenandoahMarkTask::max_addressable()); 237 vm_exit_during_initialization("Fatal Error", buf); 238 } 239 #endif 240 241 ReservedSpace sh_rs = heap_rs.first_part(max_byte_size); 242 if (!_heap_region_special) { 243 os::commit_memory_or_exit(sh_rs.base(), _initial_size, heap_alignment, false, 244 "Cannot commit heap memory"); 245 } 246 247 BarrierSet::set_barrier_set(new ShenandoahBarrierSet(this, _heap_region)); 248 249 // Now we know the number of regions and heap sizes, initialize the heuristics. 250 initialize_heuristics(); 251 252 assert(_heap_region.byte_size() == heap_rs.size(), "Need to know reserved size for card table"); 253 254 // 255 // Worker threads must be initialized after the barrier is configured 256 // 257 _workers = new ShenandoahWorkerThreads("Shenandoah GC Threads", _max_workers); 258 if (_workers == nullptr) { 259 vm_exit_during_initialization("Failed necessary allocation."); 260 } else { 261 _workers->initialize_workers(); 262 } 263 264 if (ParallelGCThreads > 1) { 265 _safepoint_workers = new ShenandoahWorkerThreads("Safepoint Cleanup Thread", ParallelGCThreads); 266 _safepoint_workers->initialize_workers(); 267 } 268 269 // 270 // Reserve and commit memory for bitmap(s) 271 // 272 273 size_t bitmap_size_orig = ShenandoahMarkBitMap::compute_size(heap_rs.size()); 274 _bitmap_size = align_up(bitmap_size_orig, bitmap_page_size); 275 276 size_t bitmap_bytes_per_region = reg_size_bytes / ShenandoahMarkBitMap::heap_map_factor(); 277 278 guarantee(bitmap_bytes_per_region != 0, 279 "Bitmap bytes per region should not be zero"); 280 guarantee(is_power_of_2(bitmap_bytes_per_region), 281 "Bitmap bytes per region should be power of two: %zu", bitmap_bytes_per_region); 282 283 if (bitmap_page_size > bitmap_bytes_per_region) { 284 _bitmap_regions_per_slice = bitmap_page_size / bitmap_bytes_per_region; 285 _bitmap_bytes_per_slice = bitmap_page_size; 286 } else { 287 _bitmap_regions_per_slice = 1; 288 _bitmap_bytes_per_slice = bitmap_bytes_per_region; 289 } 290 291 guarantee(_bitmap_regions_per_slice >= 1, 292 "Should have at least one region per slice: %zu", 293 _bitmap_regions_per_slice); 294 295 guarantee(((_bitmap_bytes_per_slice) % bitmap_page_size) == 0, 296 "Bitmap slices should be page-granular: bps = %zu, page size = %zu", 297 _bitmap_bytes_per_slice, bitmap_page_size); 298 299 ReservedSpace bitmap = reserve(_bitmap_size, bitmap_page_size); 300 os::trace_page_sizes_for_requested_size("Mark Bitmap", 301 bitmap_size_orig, bitmap_page_size, 302 bitmap.base(), 303 bitmap.size(), bitmap.page_size()); 304 MemTracker::record_virtual_memory_tag(bitmap, mtGC); 305 _bitmap_region = MemRegion((HeapWord*) bitmap.base(), bitmap.size() / HeapWordSize); 306 _bitmap_region_special = bitmap.special(); 307 308 size_t bitmap_init_commit = _bitmap_bytes_per_slice * 309 align_up(num_committed_regions, _bitmap_regions_per_slice) / _bitmap_regions_per_slice; 310 bitmap_init_commit = MIN2(_bitmap_size, bitmap_init_commit); 311 if (!_bitmap_region_special) { 312 os::commit_memory_or_exit((char *) _bitmap_region.start(), bitmap_init_commit, bitmap_page_size, false, 313 "Cannot commit bitmap memory"); 314 } 315 316 _marking_context = new ShenandoahMarkingContext(_heap_region, _bitmap_region, _num_regions); 317 318 if (ShenandoahVerify) { 319 ReservedSpace verify_bitmap = reserve(_bitmap_size, bitmap_page_size); 320 os::trace_page_sizes_for_requested_size("Verify Bitmap", 321 bitmap_size_orig, bitmap_page_size, 322 verify_bitmap.base(), 323 verify_bitmap.size(), verify_bitmap.page_size()); 324 if (!verify_bitmap.special()) { 325 os::commit_memory_or_exit(verify_bitmap.base(), verify_bitmap.size(), bitmap_page_size, false, 326 "Cannot commit verification bitmap memory"); 327 } 328 MemTracker::record_virtual_memory_tag(verify_bitmap, mtGC); 329 MemRegion verify_bitmap_region = MemRegion((HeapWord *) verify_bitmap.base(), verify_bitmap.size() / HeapWordSize); 330 _verification_bit_map.initialize(_heap_region, verify_bitmap_region); 331 _verifier = new ShenandoahVerifier(this, &_verification_bit_map); 332 } 333 334 // Reserve aux bitmap for use in object_iterate(). We don't commit it here. 335 size_t aux_bitmap_page_size = bitmap_page_size; 336 337 ReservedSpace aux_bitmap = reserve(_bitmap_size, aux_bitmap_page_size); 338 os::trace_page_sizes_for_requested_size("Aux Bitmap", 339 bitmap_size_orig, aux_bitmap_page_size, 340 aux_bitmap.base(), 341 aux_bitmap.size(), aux_bitmap.page_size()); 342 MemTracker::record_virtual_memory_tag(aux_bitmap, mtGC); 343 _aux_bitmap_region = MemRegion((HeapWord*) aux_bitmap.base(), aux_bitmap.size() / HeapWordSize); 344 _aux_bitmap_region_special = aux_bitmap.special(); 345 _aux_bit_map.initialize(_heap_region, _aux_bitmap_region); 346 347 // 348 // Create regions and region sets 349 // 350 size_t region_align = align_up(sizeof(ShenandoahHeapRegion), SHENANDOAH_CACHE_LINE_SIZE); 351 size_t region_storage_size_orig = region_align * _num_regions; 352 size_t region_storage_size = align_up(region_storage_size_orig, 353 MAX2(region_page_size, os::vm_allocation_granularity())); 354 355 ReservedSpace region_storage = reserve(region_storage_size, region_page_size); 356 os::trace_page_sizes_for_requested_size("Region Storage", 357 region_storage_size_orig, region_page_size, 358 region_storage.base(), 359 region_storage.size(), region_storage.page_size()); 360 MemTracker::record_virtual_memory_tag(region_storage, mtGC); 361 if (!region_storage.special()) { 362 os::commit_memory_or_exit(region_storage.base(), region_storage_size, region_page_size, false, 363 "Cannot commit region memory"); 364 } 365 366 // Try to fit the collection set bitmap at lower addresses. This optimizes code generation for cset checks. 367 // Go up until a sensible limit (subject to encoding constraints) and try to reserve the space there. 368 // If not successful, bite a bullet and allocate at whatever address. 369 { 370 const size_t cset_align = MAX2<size_t>(os::vm_page_size(), os::vm_allocation_granularity()); 371 const size_t cset_size = align_up(((size_t) sh_rs.base() + sh_rs.size()) >> ShenandoahHeapRegion::region_size_bytes_shift(), cset_align); 372 const size_t cset_page_size = os::vm_page_size(); 373 374 uintptr_t min = round_up_power_of_2(cset_align); 375 uintptr_t max = (1u << 30u); 376 ReservedSpace cset_rs; 377 378 for (uintptr_t addr = min; addr <= max; addr <<= 1u) { 379 char* req_addr = (char*)addr; 380 assert(is_aligned(req_addr, cset_align), "Should be aligned"); 381 cset_rs = MemoryReserver::reserve(req_addr, cset_size, cset_align, cset_page_size, mtGC); 382 if (cset_rs.is_reserved()) { 383 assert(cset_rs.base() == req_addr, "Allocated where requested: " PTR_FORMAT ", " PTR_FORMAT, p2i(cset_rs.base()), addr); 384 _collection_set = new ShenandoahCollectionSet(this, cset_rs, sh_rs.base()); 385 break; 386 } 387 } 388 389 if (_collection_set == nullptr) { 390 cset_rs = MemoryReserver::reserve(cset_size, cset_align, os::vm_page_size(), mtGC); 391 if (!cset_rs.is_reserved()) { 392 vm_exit_during_initialization("Cannot reserve memory for collection set"); 393 } 394 395 _collection_set = new ShenandoahCollectionSet(this, cset_rs, sh_rs.base()); 396 } 397 os::trace_page_sizes_for_requested_size("Collection Set", 398 cset_size, cset_page_size, 399 cset_rs.base(), 400 cset_rs.size(), cset_rs.page_size()); 401 } 402 403 _regions = NEW_C_HEAP_ARRAY(ShenandoahHeapRegion*, _num_regions, mtGC); 404 _affiliations = NEW_C_HEAP_ARRAY(uint8_t, _num_regions, mtGC); 405 406 { 407 ShenandoahHeapLocker locker(lock()); 408 _free_set = new ShenandoahFreeSet(this, _num_regions); 409 for (size_t i = 0; i < _num_regions; i++) { 410 HeapWord* start = (HeapWord*)sh_rs.base() + ShenandoahHeapRegion::region_size_words() * i; 411 bool is_committed = i < num_committed_regions; 412 void* loc = region_storage.base() + i * region_align; 413 414 ShenandoahHeapRegion* r = new (loc) ShenandoahHeapRegion(start, i, is_committed); 415 assert(is_aligned(r, SHENANDOAH_CACHE_LINE_SIZE), "Sanity"); 416 417 _marking_context->initialize_top_at_mark_start(r); 418 _regions[i] = r; 419 assert(!collection_set()->is_in(i), "New region should not be in collection set"); 420 421 _affiliations[i] = ShenandoahAffiliation::FREE; 422 } 423 424 size_t young_cset_regions, old_cset_regions; 425 426 // We are initializing free set. We ignore cset region tallies. 427 size_t first_old, last_old, num_old; 428 _free_set->prepare_to_rebuild(young_cset_regions, old_cset_regions, first_old, last_old, num_old); 429 _free_set->finish_rebuild(young_cset_regions, old_cset_regions, num_old); 430 } 431 432 if (AlwaysPreTouch) { 433 // For NUMA, it is important to pre-touch the storage under bitmaps with worker threads, 434 // before initialize() below zeroes it with initializing thread. For any given region, 435 // we touch the region and the corresponding bitmaps from the same thread. 436 ShenandoahPushWorkerScope scope(workers(), _max_workers, false); 437 438 _pretouch_heap_page_size = heap_page_size; 439 _pretouch_bitmap_page_size = bitmap_page_size; 440 441 // OS memory managers may want to coalesce back-to-back pages. Make their jobs 442 // simpler by pre-touching continuous spaces (heap and bitmap) separately. 443 444 ShenandoahPretouchBitmapTask bcl(bitmap.base(), _bitmap_size, _pretouch_bitmap_page_size); 445 _workers->run_task(&bcl); 446 447 ShenandoahPretouchHeapTask hcl(_pretouch_heap_page_size); 448 _workers->run_task(&hcl); 449 } 450 451 // 452 // Initialize the rest of GC subsystems 453 // 454 455 _liveness_cache = NEW_C_HEAP_ARRAY(ShenandoahLiveData*, _max_workers, mtGC); 456 for (uint worker = 0; worker < _max_workers; worker++) { 457 _liveness_cache[worker] = NEW_C_HEAP_ARRAY(ShenandoahLiveData, _num_regions, mtGC); 458 Copy::fill_to_bytes(_liveness_cache[worker], _num_regions * sizeof(ShenandoahLiveData)); 459 } 460 461 // There should probably be Shenandoah-specific options for these, 462 // just as there are G1-specific options. 463 { 464 ShenandoahSATBMarkQueueSet& satbqs = ShenandoahBarrierSet::satb_mark_queue_set(); 465 satbqs.set_process_completed_buffers_threshold(20); // G1SATBProcessCompletedThreshold 466 satbqs.set_buffer_enqueue_threshold_percentage(60); // G1SATBBufferEnqueueingThresholdPercent 467 } 468 469 _monitoring_support = new ShenandoahMonitoringSupport(this); 470 _phase_timings = new ShenandoahPhaseTimings(max_workers()); 471 ShenandoahCodeRoots::initialize(); 472 473 if (ShenandoahPacing) { 474 _pacer = new ShenandoahPacer(this); 475 _pacer->setup_for_idle(); 476 } 477 478 initialize_controller(); 479 480 if (ShenandoahUncommit) { 481 _uncommit_thread = new ShenandoahUncommitThread(this); 482 } 483 484 print_init_logger(); 485 486 FullGCForwarding::initialize(_heap_region); 487 488 return JNI_OK; 489 } 490 491 void ShenandoahHeap::initialize_controller() { 492 _control_thread = new ShenandoahControlThread(); 493 } 494 495 void ShenandoahHeap::print_init_logger() const { 496 ShenandoahInitLogger::print(); 497 } 498 499 void ShenandoahHeap::initialize_mode() { 500 if (ShenandoahGCMode != nullptr) { 501 if (strcmp(ShenandoahGCMode, "satb") == 0) { 502 _gc_mode = new ShenandoahSATBMode(); 503 } else if (strcmp(ShenandoahGCMode, "passive") == 0) { 504 _gc_mode = new ShenandoahPassiveMode(); 505 } else if (strcmp(ShenandoahGCMode, "generational") == 0) { 506 _gc_mode = new ShenandoahGenerationalMode(); 507 } else { 508 vm_exit_during_initialization("Unknown -XX:ShenandoahGCMode option"); 509 } 510 } else { 511 vm_exit_during_initialization("Unknown -XX:ShenandoahGCMode option (null)"); 512 } 513 _gc_mode->initialize_flags(); 514 if (_gc_mode->is_diagnostic() && !UnlockDiagnosticVMOptions) { 515 vm_exit_during_initialization( 516 err_msg("GC mode \"%s\" is diagnostic, and must be enabled via -XX:+UnlockDiagnosticVMOptions.", 517 _gc_mode->name())); 518 } 519 if (_gc_mode->is_experimental() && !UnlockExperimentalVMOptions) { 520 vm_exit_during_initialization( 521 err_msg("GC mode \"%s\" is experimental, and must be enabled via -XX:+UnlockExperimentalVMOptions.", 522 _gc_mode->name())); 523 } 524 } 525 526 void ShenandoahHeap::initialize_heuristics() { 527 _global_generation = new ShenandoahGlobalGeneration(mode()->is_generational(), max_workers(), max_capacity(), max_capacity()); 528 _global_generation->initialize_heuristics(mode()); 529 } 530 531 #ifdef _MSC_VER 532 #pragma warning( push ) 533 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list 534 #endif 535 536 ShenandoahHeap::ShenandoahHeap(ShenandoahCollectorPolicy* policy) : 537 CollectedHeap(), 538 _gc_generation(nullptr), 539 _active_generation(nullptr), 540 _initial_size(0), 541 _committed(0), 542 _max_workers(MAX3(ConcGCThreads, ParallelGCThreads, 1U)), 543 _workers(nullptr), 544 _safepoint_workers(nullptr), 545 _heap_region_special(false), 546 _num_regions(0), 547 _regions(nullptr), 548 _affiliations(nullptr), 549 _gc_state_changed(false), 550 _gc_no_progress_count(0), 551 _cancel_requested_time(0), 552 _update_refs_iterator(this), 553 _global_generation(nullptr), 554 _control_thread(nullptr), 555 _uncommit_thread(nullptr), 556 _young_generation(nullptr), 557 _old_generation(nullptr), 558 _shenandoah_policy(policy), 559 _gc_mode(nullptr), 560 _free_set(nullptr), 561 _pacer(nullptr), 562 _verifier(nullptr), 563 _phase_timings(nullptr), 564 _monitoring_support(nullptr), 565 _memory_pool(nullptr), 566 _stw_memory_manager("Shenandoah Pauses"), 567 _cycle_memory_manager("Shenandoah Cycles"), 568 _gc_timer(new ConcurrentGCTimer()), 569 _log_min_obj_alignment_in_bytes(LogMinObjAlignmentInBytes), 570 _marking_context(nullptr), 571 _bitmap_size(0), 572 _bitmap_regions_per_slice(0), 573 _bitmap_bytes_per_slice(0), 574 _bitmap_region_special(false), 575 _aux_bitmap_region_special(false), 576 _liveness_cache(nullptr), 577 _collection_set(nullptr) 578 { 579 // Initialize GC mode early, many subsequent initialization procedures depend on it 580 initialize_mode(); 581 _cancelled_gc.set(GCCause::_no_gc); 582 } 583 584 #ifdef _MSC_VER 585 #pragma warning( pop ) 586 #endif 587 588 void ShenandoahHeap::print_heap_on(outputStream* st) const { 589 st->print_cr("Shenandoah Heap"); 590 st->print_cr(" %zu%s max, %zu%s soft max, %zu%s committed, %zu%s used", 591 byte_size_in_proper_unit(max_capacity()), proper_unit_for_byte_size(max_capacity()), 592 byte_size_in_proper_unit(soft_max_capacity()), proper_unit_for_byte_size(soft_max_capacity()), 593 byte_size_in_proper_unit(committed()), proper_unit_for_byte_size(committed()), 594 byte_size_in_proper_unit(used()), proper_unit_for_byte_size(used())); 595 st->print_cr(" %zu x %zu %s regions", 596 num_regions(), 597 byte_size_in_proper_unit(ShenandoahHeapRegion::region_size_bytes()), 598 proper_unit_for_byte_size(ShenandoahHeapRegion::region_size_bytes())); 599 600 st->print("Status: "); 601 if (has_forwarded_objects()) st->print("has forwarded objects, "); 602 if (!mode()->is_generational()) { 603 if (is_concurrent_mark_in_progress()) st->print("marking,"); 604 } else { 605 if (is_concurrent_old_mark_in_progress()) st->print("old marking, "); 606 if (is_concurrent_young_mark_in_progress()) st->print("young marking, "); 607 } 608 if (is_evacuation_in_progress()) st->print("evacuating, "); 609 if (is_update_refs_in_progress()) st->print("updating refs, "); 610 if (is_degenerated_gc_in_progress()) st->print("degenerated gc, "); 611 if (is_full_gc_in_progress()) st->print("full gc, "); 612 if (is_full_gc_move_in_progress()) st->print("full gc move, "); 613 if (is_concurrent_weak_root_in_progress()) st->print("concurrent weak roots, "); 614 if (is_concurrent_strong_root_in_progress() && 615 !is_concurrent_weak_root_in_progress()) st->print("concurrent strong roots, "); 616 617 if (cancelled_gc()) { 618 st->print("cancelled"); 619 } else { 620 st->print("not cancelled"); 621 } 622 st->cr(); 623 624 st->print_cr("Reserved region:"); 625 st->print_cr(" - [" PTR_FORMAT ", " PTR_FORMAT ") ", 626 p2i(reserved_region().start()), 627 p2i(reserved_region().end())); 628 629 ShenandoahCollectionSet* cset = collection_set(); 630 st->print_cr("Collection set:"); 631 if (cset != nullptr) { 632 st->print_cr(" - map (vanilla): " PTR_FORMAT, p2i(cset->map_address())); 633 st->print_cr(" - map (biased): " PTR_FORMAT, p2i(cset->biased_map_address())); 634 } else { 635 st->print_cr(" (null)"); 636 } 637 638 st->cr(); 639 640 if (Verbose) { 641 st->cr(); 642 print_heap_regions_on(st); 643 } 644 } 645 646 void ShenandoahHeap::print_gc_on(outputStream* st) const { 647 print_heap_regions_on(st); 648 } 649 650 class ShenandoahInitWorkerGCLABClosure : public ThreadClosure { 651 public: 652 void do_thread(Thread* thread) { 653 assert(thread != nullptr, "Sanity"); 654 ShenandoahThreadLocalData::initialize_gclab(thread); 655 } 656 }; 657 658 void ShenandoahHeap::post_initialize() { 659 CollectedHeap::post_initialize(); 660 661 // Schedule periodic task to report on gc thread CPU utilization 662 _mmu_tracker.initialize(); 663 664 MutexLocker ml(Threads_lock); 665 666 ShenandoahInitWorkerGCLABClosure init_gclabs; 667 _workers->threads_do(&init_gclabs); 668 669 // gclab can not be initialized early during VM startup, as it can not determinate its max_size. 670 // Now, we will let WorkerThreads to initialize gclab when new worker is created. 671 _workers->set_initialize_gclab(); 672 673 // Note that the safepoint workers may require gclabs if the threads are used to create a heap dump 674 // during a concurrent evacuation phase. 675 if (_safepoint_workers != nullptr) { 676 _safepoint_workers->threads_do(&init_gclabs); 677 _safepoint_workers->set_initialize_gclab(); 678 } 679 680 JFR_ONLY(ShenandoahJFRSupport::register_jfr_type_serializers();) 681 } 682 683 ShenandoahHeuristics* ShenandoahHeap::heuristics() { 684 return _global_generation->heuristics(); 685 } 686 687 size_t ShenandoahHeap::used() const { 688 return global_generation()->used(); 689 } 690 691 size_t ShenandoahHeap::committed() const { 692 return Atomic::load(&_committed); 693 } 694 695 void ShenandoahHeap::increase_committed(size_t bytes) { 696 shenandoah_assert_heaplocked_or_safepoint(); 697 _committed += bytes; 698 } 699 700 void ShenandoahHeap::decrease_committed(size_t bytes) { 701 shenandoah_assert_heaplocked_or_safepoint(); 702 _committed -= bytes; 703 } 704 705 // For tracking usage based on allocations, it should be the case that: 706 // * The sum of regions::used == heap::used 707 // * The sum of a generation's regions::used == generation::used 708 // * The sum of a generation's humongous regions::free == generation::humongous_waste 709 // These invariants are checked by the verifier on GC safepoints. 710 // 711 // Additional notes: 712 // * When a mutator's allocation request causes a region to be retired, the 713 // free memory left in that region is considered waste. It does not contribute 714 // to the usage, but it _does_ contribute to allocation rate. 715 // * The bottom of a PLAB must be aligned on card size. In some cases this will 716 // require padding in front of the PLAB (a filler object). Because this padding 717 // is included in the region's used memory we include the padding in the usage 718 // accounting as waste. 719 // * Mutator allocations are used to compute an allocation rate. They are also 720 // sent to the Pacer for those purposes. 721 // * There are three sources of waste: 722 // 1. The padding used to align a PLAB on card size 723 // 2. Region's free is less than minimum TLAB size and is retired 724 // 3. The unused portion of memory in the last region of a humongous object 725 void ShenandoahHeap::increase_used(const ShenandoahAllocRequest& req) { 726 size_t actual_bytes = req.actual_size() * HeapWordSize; 727 size_t wasted_bytes = req.waste() * HeapWordSize; 728 ShenandoahGeneration* generation = generation_for(req.affiliation()); 729 730 if (req.is_gc_alloc()) { 731 assert(wasted_bytes == 0 || req.type() == ShenandoahAllocRequest::_alloc_plab, "Only PLABs have waste"); 732 increase_used(generation, actual_bytes + wasted_bytes); 733 } else { 734 assert(req.is_mutator_alloc(), "Expected mutator alloc here"); 735 // padding and actual size both count towards allocation counter 736 generation->increase_allocated(actual_bytes + wasted_bytes); 737 738 // only actual size counts toward usage for mutator allocations 739 increase_used(generation, actual_bytes); 740 741 // notify pacer of both actual size and waste 742 notify_mutator_alloc_words(req.actual_size(), req.waste()); 743 744 if (wasted_bytes > 0 && ShenandoahHeapRegion::requires_humongous(req.actual_size())) { 745 increase_humongous_waste(generation,wasted_bytes); 746 } 747 } 748 } 749 750 void ShenandoahHeap::increase_humongous_waste(ShenandoahGeneration* generation, size_t bytes) { 751 generation->increase_humongous_waste(bytes); 752 if (!generation->is_global()) { 753 global_generation()->increase_humongous_waste(bytes); 754 } 755 } 756 757 void ShenandoahHeap::decrease_humongous_waste(ShenandoahGeneration* generation, size_t bytes) { 758 generation->decrease_humongous_waste(bytes); 759 if (!generation->is_global()) { 760 global_generation()->decrease_humongous_waste(bytes); 761 } 762 } 763 764 void ShenandoahHeap::increase_used(ShenandoahGeneration* generation, size_t bytes) { 765 generation->increase_used(bytes); 766 if (!generation->is_global()) { 767 global_generation()->increase_used(bytes); 768 } 769 } 770 771 void ShenandoahHeap::decrease_used(ShenandoahGeneration* generation, size_t bytes) { 772 generation->decrease_used(bytes); 773 if (!generation->is_global()) { 774 global_generation()->decrease_used(bytes); 775 } 776 } 777 778 void ShenandoahHeap::notify_mutator_alloc_words(size_t words, size_t waste) { 779 if (ShenandoahPacing) { 780 control_thread()->pacing_notify_alloc(words); 781 if (waste > 0) { 782 pacer()->claim_for_alloc<true>(waste); 783 } 784 } 785 } 786 787 size_t ShenandoahHeap::capacity() const { 788 return committed(); 789 } 790 791 size_t ShenandoahHeap::max_capacity() const { 792 return _num_regions * ShenandoahHeapRegion::region_size_bytes(); 793 } 794 795 size_t ShenandoahHeap::soft_max_capacity() const { 796 size_t v = Atomic::load(&_soft_max_size); 797 assert(min_capacity() <= v && v <= max_capacity(), 798 "Should be in bounds: %zu <= %zu <= %zu", 799 min_capacity(), v, max_capacity()); 800 return v; 801 } 802 803 void ShenandoahHeap::set_soft_max_capacity(size_t v) { 804 assert(min_capacity() <= v && v <= max_capacity(), 805 "Should be in bounds: %zu <= %zu <= %zu", 806 min_capacity(), v, max_capacity()); 807 Atomic::store(&_soft_max_size, v); 808 } 809 810 size_t ShenandoahHeap::min_capacity() const { 811 return _minimum_size; 812 } 813 814 size_t ShenandoahHeap::initial_capacity() const { 815 return _initial_size; 816 } 817 818 bool ShenandoahHeap::is_in(const void* p) const { 819 if (!is_in_reserved(p)) { 820 return false; 821 } 822 823 if (is_full_gc_move_in_progress()) { 824 // Full GC move is running, we do not have a consistent region 825 // information yet. But we know the pointer is in heap. 826 return true; 827 } 828 829 // Now check if we point to a live section in active region. 830 const ShenandoahHeapRegion* r = heap_region_containing(p); 831 if (p >= r->top()) { 832 return false; 833 } 834 835 if (r->is_active()) { 836 return true; 837 } 838 839 // The region is trash, but won't be recycled until after concurrent weak 840 // roots. We also don't allow mutators to allocate from trash regions 841 // during weak roots. Concurrent class unloading may access unmarked oops 842 // in trash regions. 843 return r->is_trash() && is_concurrent_weak_root_in_progress(); 844 } 845 846 void ShenandoahHeap::notify_soft_max_changed() { 847 if (_uncommit_thread != nullptr) { 848 _uncommit_thread->notify_soft_max_changed(); 849 } 850 } 851 852 void ShenandoahHeap::notify_explicit_gc_requested() { 853 if (_uncommit_thread != nullptr) { 854 _uncommit_thread->notify_explicit_gc_requested(); 855 } 856 } 857 858 bool ShenandoahHeap::check_soft_max_changed() { 859 size_t new_soft_max = Atomic::load(&SoftMaxHeapSize); 860 size_t old_soft_max = soft_max_capacity(); 861 if (new_soft_max != old_soft_max) { 862 new_soft_max = MAX2(min_capacity(), new_soft_max); 863 new_soft_max = MIN2(max_capacity(), new_soft_max); 864 if (new_soft_max != old_soft_max) { 865 log_info(gc)("Soft Max Heap Size: %zu%s -> %zu%s", 866 byte_size_in_proper_unit(old_soft_max), proper_unit_for_byte_size(old_soft_max), 867 byte_size_in_proper_unit(new_soft_max), proper_unit_for_byte_size(new_soft_max) 868 ); 869 set_soft_max_capacity(new_soft_max); 870 return true; 871 } 872 } 873 return false; 874 } 875 876 void ShenandoahHeap::notify_heap_changed() { 877 // Update monitoring counters when we took a new region. This amortizes the 878 // update costs on slow path. 879 monitoring_support()->notify_heap_changed(); 880 _heap_changed.try_set(); 881 } 882 883 void ShenandoahHeap::set_forced_counters_update(bool value) { 884 monitoring_support()->set_forced_counters_update(value); 885 } 886 887 void ShenandoahHeap::handle_force_counters_update() { 888 monitoring_support()->handle_force_counters_update(); 889 } 890 891 HeapWord* ShenandoahHeap::allocate_from_gclab_slow(Thread* thread, size_t size) { 892 // New object should fit the GCLAB size 893 size_t min_size = MAX2(size, PLAB::min_size()); 894 895 // Figure out size of new GCLAB, looking back at heuristics. Expand aggressively. 896 size_t new_size = ShenandoahThreadLocalData::gclab_size(thread) * 2; 897 898 new_size = MIN2(new_size, PLAB::max_size()); 899 new_size = MAX2(new_size, PLAB::min_size()); 900 901 // Record new heuristic value even if we take any shortcut. This captures 902 // the case when moderately-sized objects always take a shortcut. At some point, 903 // heuristics should catch up with them. 904 log_debug(gc, free)("Set new GCLAB size: %zu", new_size); 905 ShenandoahThreadLocalData::set_gclab_size(thread, new_size); 906 907 if (new_size < size) { 908 // New size still does not fit the object. Fall back to shared allocation. 909 // This avoids retiring perfectly good GCLABs, when we encounter a large object. 910 log_debug(gc, free)("New gclab size (%zu) is too small for %zu", new_size, size); 911 return nullptr; 912 } 913 914 // Retire current GCLAB, and allocate a new one. 915 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread); 916 gclab->retire(); 917 918 size_t actual_size = 0; 919 HeapWord* gclab_buf = allocate_new_gclab(min_size, new_size, &actual_size); 920 if (gclab_buf == nullptr) { 921 return nullptr; 922 } 923 924 assert (size <= actual_size, "allocation should fit"); 925 926 // ...and clear or zap just allocated TLAB, if needed. 927 if (ZeroTLAB) { 928 Copy::zero_to_words(gclab_buf, actual_size); 929 } else if (ZapTLAB) { 930 // Skip mangling the space corresponding to the object header to 931 // ensure that the returned space is not considered parsable by 932 // any concurrent GC thread. 933 size_t hdr_size = oopDesc::header_size(); 934 Copy::fill_to_words(gclab_buf + hdr_size, actual_size - hdr_size, badHeapWordVal); 935 } 936 gclab->set_buf(gclab_buf, actual_size); 937 return gclab->allocate(size); 938 } 939 940 // Called from stubs in JIT code or interpreter 941 HeapWord* ShenandoahHeap::allocate_new_tlab(size_t min_size, 942 size_t requested_size, 943 size_t* actual_size) { 944 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_tlab(min_size, requested_size); 945 HeapWord* res = allocate_memory(req); 946 if (res != nullptr) { 947 *actual_size = req.actual_size(); 948 } else { 949 *actual_size = 0; 950 } 951 return res; 952 } 953 954 HeapWord* ShenandoahHeap::allocate_new_gclab(size_t min_size, 955 size_t word_size, 956 size_t* actual_size) { 957 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_gclab(min_size, word_size); 958 HeapWord* res = allocate_memory(req); 959 if (res != nullptr) { 960 *actual_size = req.actual_size(); 961 } else { 962 *actual_size = 0; 963 } 964 return res; 965 } 966 967 HeapWord* ShenandoahHeap::allocate_memory(ShenandoahAllocRequest& req) { 968 intptr_t pacer_epoch = 0; 969 bool in_new_region = false; 970 HeapWord* result = nullptr; 971 972 if (req.is_mutator_alloc()) { 973 if (ShenandoahPacing) { 974 pacer()->pace_for_alloc(req.size()); 975 pacer_epoch = pacer()->epoch(); 976 } 977 978 if (!ShenandoahAllocFailureALot || !should_inject_alloc_failure()) { 979 result = allocate_memory_under_lock(req, in_new_region); 980 } 981 982 // Check that gc overhead is not exceeded. 983 // 984 // Shenandoah will grind along for quite a while allocating one 985 // object at a time using shared (non-tlab) allocations. This check 986 // is testing that the GC overhead limit has not been exceeded. 987 // This will notify the collector to start a cycle, but will raise 988 // an OOME to the mutator if the last Full GCs have not made progress. 989 // gc_no_progress_count is incremented following each degen or full GC that fails to achieve is_good_progress(). 990 if (result == nullptr && !req.is_lab_alloc() && get_gc_no_progress_count() > ShenandoahNoProgressThreshold) { 991 control_thread()->handle_alloc_failure(req, false); 992 req.set_actual_size(0); 993 return nullptr; 994 } 995 996 if (result == nullptr) { 997 // Block until control thread reacted, then retry allocation. 998 // 999 // It might happen that one of the threads requesting allocation would unblock 1000 // way later after GC happened, only to fail the second allocation, because 1001 // other threads have already depleted the free storage. In this case, a better 1002 // strategy is to try again, until at least one full GC has completed. 1003 // 1004 // Stop retrying and return nullptr to cause OOMError exception if our allocation failed even after: 1005 // a) We experienced a GC that had good progress, or 1006 // b) We experienced at least one Full GC (whether or not it had good progress) 1007 1008 const size_t original_count = shenandoah_policy()->full_gc_count(); 1009 while (result == nullptr && should_retry_allocation(original_count)) { 1010 control_thread()->handle_alloc_failure(req, true); 1011 result = allocate_memory_under_lock(req, in_new_region); 1012 } 1013 if (result != nullptr) { 1014 // If our allocation request has been satisfied after it initially failed, we count this as good gc progress 1015 notify_gc_progress(); 1016 } 1017 if (log_develop_is_enabled(Debug, gc, alloc)) { 1018 ResourceMark rm; 1019 log_debug(gc, alloc)("Thread: %s, Result: " PTR_FORMAT ", Request: %s, Size: %zu" 1020 ", Original: %zu, Latest: %zu", 1021 Thread::current()->name(), p2i(result), req.type_string(), req.size(), 1022 original_count, get_gc_no_progress_count()); 1023 } 1024 } 1025 } else { 1026 assert(req.is_gc_alloc(), "Can only accept GC allocs here"); 1027 result = allocate_memory_under_lock(req, in_new_region); 1028 // Do not call handle_alloc_failure() here, because we cannot block. 1029 // The allocation failure would be handled by the LRB slowpath with handle_alloc_failure_evac(). 1030 } 1031 1032 if (in_new_region) { 1033 notify_heap_changed(); 1034 } 1035 1036 if (result == nullptr) { 1037 req.set_actual_size(0); 1038 } 1039 1040 // This is called regardless of the outcome of the allocation to account 1041 // for any waste created by retiring regions with this request. 1042 increase_used(req); 1043 1044 if (result != nullptr) { 1045 size_t requested = req.size(); 1046 size_t actual = req.actual_size(); 1047 1048 assert (req.is_lab_alloc() || (requested == actual), 1049 "Only LAB allocations are elastic: %s, requested = %zu, actual = %zu", 1050 ShenandoahAllocRequest::alloc_type_to_string(req.type()), requested, actual); 1051 1052 if (req.is_mutator_alloc()) { 1053 // If we requested more than we were granted, give the rest back to pacer. 1054 // This only matters if we are in the same pacing epoch: do not try to unpace 1055 // over the budget for the other phase. 1056 if (ShenandoahPacing && (pacer_epoch > 0) && (requested > actual)) { 1057 pacer()->unpace_for_alloc(pacer_epoch, requested - actual); 1058 } 1059 } 1060 } 1061 1062 return result; 1063 } 1064 1065 inline bool ShenandoahHeap::should_retry_allocation(size_t original_full_gc_count) const { 1066 return shenandoah_policy()->full_gc_count() == original_full_gc_count 1067 && !shenandoah_policy()->is_at_shutdown(); 1068 } 1069 1070 HeapWord* ShenandoahHeap::allocate_memory_under_lock(ShenandoahAllocRequest& req, bool& in_new_region) { 1071 // If we are dealing with mutator allocation, then we may need to block for safepoint. 1072 // We cannot block for safepoint for GC allocations, because there is a high chance 1073 // we are already running at safepoint or from stack watermark machinery, and we cannot 1074 // block again. 1075 ShenandoahHeapLocker locker(lock(), req.is_mutator_alloc()); 1076 1077 // Make sure the old generation has room for either evacuations or promotions before trying to allocate. 1078 if (req.is_old() && !old_generation()->can_allocate(req)) { 1079 return nullptr; 1080 } 1081 1082 // If TLAB request size is greater than available, allocate() will attempt to downsize request to fit within available 1083 // memory. 1084 HeapWord* result = _free_set->allocate(req, in_new_region); 1085 1086 // Record the plab configuration for this result and register the object. 1087 if (result != nullptr && req.is_old()) { 1088 old_generation()->configure_plab_for_current_thread(req); 1089 if (req.type() == ShenandoahAllocRequest::_alloc_shared_gc) { 1090 // Register the newly allocated object while we're holding the global lock since there's no synchronization 1091 // built in to the implementation of register_object(). There are potential races when multiple independent 1092 // threads are allocating objects, some of which might span the same card region. For example, consider 1093 // a card table's memory region within which three objects are being allocated by three different threads: 1094 // 1095 // objects being "concurrently" allocated: 1096 // [-----a------][-----b-----][--------------c------------------] 1097 // [---- card table memory range --------------] 1098 // 1099 // Before any objects are allocated, this card's memory range holds no objects. Note that allocation of object a 1100 // wants to set the starts-object, first-start, and last-start attributes of the preceding card region. 1101 // Allocation of object b wants to set the starts-object, first-start, and last-start attributes of this card region. 1102 // Allocation of object c also wants to set the starts-object, first-start, and last-start attributes of this 1103 // card region. 1104 // 1105 // The thread allocating b and the thread allocating c can "race" in various ways, resulting in confusion, such as 1106 // last-start representing object b while first-start represents object c. This is why we need to require all 1107 // register_object() invocations to be "mutually exclusive" with respect to each card's memory range. 1108 old_generation()->card_scan()->register_object(result); 1109 } 1110 } 1111 1112 return result; 1113 } 1114 1115 HeapWord* ShenandoahHeap::mem_allocate(size_t size, 1116 bool* gc_overhead_limit_was_exceeded) { 1117 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_shared(size); 1118 return allocate_memory(req); 1119 } 1120 1121 MetaWord* ShenandoahHeap::satisfy_failed_metadata_allocation(ClassLoaderData* loader_data, 1122 size_t size, 1123 Metaspace::MetadataType mdtype) { 1124 MetaWord* result; 1125 1126 // Inform metaspace OOM to GC heuristics if class unloading is possible. 1127 ShenandoahHeuristics* h = global_generation()->heuristics(); 1128 if (h->can_unload_classes()) { 1129 h->record_metaspace_oom(); 1130 } 1131 1132 // Expand and retry allocation 1133 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype); 1134 if (result != nullptr) { 1135 return result; 1136 } 1137 1138 // Start full GC 1139 collect(GCCause::_metadata_GC_clear_soft_refs); 1140 1141 // Retry allocation 1142 result = loader_data->metaspace_non_null()->allocate(size, mdtype); 1143 if (result != nullptr) { 1144 return result; 1145 } 1146 1147 // Expand and retry allocation 1148 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype); 1149 if (result != nullptr) { 1150 return result; 1151 } 1152 1153 // Out of memory 1154 return nullptr; 1155 } 1156 1157 class ShenandoahConcurrentEvacuateRegionObjectClosure : public ObjectClosure { 1158 private: 1159 ShenandoahHeap* const _heap; 1160 Thread* const _thread; 1161 public: 1162 ShenandoahConcurrentEvacuateRegionObjectClosure(ShenandoahHeap* heap) : 1163 _heap(heap), _thread(Thread::current()) {} 1164 1165 void do_object(oop p) { 1166 shenandoah_assert_marked(nullptr, p); 1167 if (!p->is_forwarded()) { 1168 _heap->evacuate_object(p, _thread); 1169 } 1170 } 1171 }; 1172 1173 class ShenandoahEvacuationTask : public WorkerTask { 1174 private: 1175 ShenandoahHeap* const _sh; 1176 ShenandoahCollectionSet* const _cs; 1177 bool _concurrent; 1178 public: 1179 ShenandoahEvacuationTask(ShenandoahHeap* sh, 1180 ShenandoahCollectionSet* cs, 1181 bool concurrent) : 1182 WorkerTask("Shenandoah Evacuation"), 1183 _sh(sh), 1184 _cs(cs), 1185 _concurrent(concurrent) 1186 {} 1187 1188 void work(uint worker_id) { 1189 if (_concurrent) { 1190 ShenandoahConcurrentWorkerSession worker_session(worker_id); 1191 ShenandoahSuspendibleThreadSetJoiner stsj; 1192 ShenandoahEvacOOMScope oom_evac_scope; 1193 do_work(); 1194 } else { 1195 ShenandoahParallelWorkerSession worker_session(worker_id); 1196 ShenandoahEvacOOMScope oom_evac_scope; 1197 do_work(); 1198 } 1199 } 1200 1201 private: 1202 void do_work() { 1203 ShenandoahConcurrentEvacuateRegionObjectClosure cl(_sh); 1204 ShenandoahHeapRegion* r; 1205 while ((r =_cs->claim_next()) != nullptr) { 1206 assert(r->has_live(), "Region %zu should have been reclaimed early", r->index()); 1207 _sh->marked_object_iterate(r, &cl); 1208 1209 if (ShenandoahPacing) { 1210 _sh->pacer()->report_evac(r->used() >> LogHeapWordSize); 1211 } 1212 1213 if (_sh->check_cancelled_gc_and_yield(_concurrent)) { 1214 break; 1215 } 1216 } 1217 } 1218 }; 1219 1220 class ShenandoahRetireGCLABClosure : public ThreadClosure { 1221 private: 1222 bool const _resize; 1223 public: 1224 explicit ShenandoahRetireGCLABClosure(bool resize) : _resize(resize) {} 1225 void do_thread(Thread* thread) override { 1226 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread); 1227 assert(gclab != nullptr, "GCLAB should be initialized for %s", thread->name()); 1228 gclab->retire(); 1229 if (_resize && ShenandoahThreadLocalData::gclab_size(thread) > 0) { 1230 ShenandoahThreadLocalData::set_gclab_size(thread, 0); 1231 } 1232 1233 if (ShenandoahHeap::heap()->mode()->is_generational()) { 1234 PLAB* plab = ShenandoahThreadLocalData::plab(thread); 1235 assert(plab != nullptr, "PLAB should be initialized for %s", thread->name()); 1236 1237 // There are two reasons to retire all plabs between old-gen evacuation passes. 1238 // 1. We need to make the plab memory parsable by remembered-set scanning. 1239 // 2. We need to establish a trustworthy UpdateWaterMark value within each old-gen heap region 1240 ShenandoahGenerationalHeap::heap()->retire_plab(plab, thread); 1241 if (_resize && ShenandoahThreadLocalData::plab_size(thread) > 0) { 1242 ShenandoahThreadLocalData::set_plab_size(thread, 0); 1243 } 1244 } 1245 } 1246 }; 1247 1248 class ShenandoahGCStatePropagator : public HandshakeClosure { 1249 public: 1250 explicit ShenandoahGCStatePropagator(char gc_state) : 1251 HandshakeClosure("Shenandoah GC State Change"), 1252 _gc_state(gc_state) {} 1253 1254 void do_thread(Thread* thread) override { 1255 ShenandoahThreadLocalData::set_gc_state(thread, _gc_state); 1256 } 1257 private: 1258 char _gc_state; 1259 }; 1260 1261 class ShenandoahPrepareForUpdateRefs : public HandshakeClosure { 1262 public: 1263 explicit ShenandoahPrepareForUpdateRefs(char gc_state) : 1264 HandshakeClosure("Shenandoah Prepare for Update Refs"), 1265 _retire(ResizeTLAB), _propagator(gc_state) {} 1266 1267 void do_thread(Thread* thread) override { 1268 _propagator.do_thread(thread); 1269 if (ShenandoahThreadLocalData::gclab(thread) != nullptr) { 1270 _retire.do_thread(thread); 1271 } 1272 } 1273 private: 1274 ShenandoahRetireGCLABClosure _retire; 1275 ShenandoahGCStatePropagator _propagator; 1276 }; 1277 1278 void ShenandoahHeap::evacuate_collection_set(bool concurrent) { 1279 ShenandoahEvacuationTask task(this, _collection_set, concurrent); 1280 workers()->run_task(&task); 1281 } 1282 1283 void ShenandoahHeap::concurrent_prepare_for_update_refs() { 1284 { 1285 // Java threads take this lock while they are being attached and added to the list of thread. 1286 // If another thread holds this lock before we update the gc state, it will receive a stale 1287 // gc state, but they will have been added to the list of java threads and so will be corrected 1288 // by the following handshake. 1289 MutexLocker lock(Threads_lock); 1290 1291 // A cancellation at this point means the degenerated cycle must resume from update-refs. 1292 set_gc_state_concurrent(EVACUATION, false); 1293 set_gc_state_concurrent(WEAK_ROOTS, false); 1294 set_gc_state_concurrent(UPDATE_REFS, true); 1295 } 1296 1297 // This will propagate the gc state and retire gclabs and plabs for threads that require it. 1298 ShenandoahPrepareForUpdateRefs prepare_for_update_refs(_gc_state.raw_value()); 1299 1300 // The handshake won't touch worker threads (or control thread, or VM thread), so do those separately. 1301 Threads::non_java_threads_do(&prepare_for_update_refs); 1302 1303 // Now retire gclabs and plabs and propagate gc_state for mutator threads 1304 Handshake::execute(&prepare_for_update_refs); 1305 1306 _update_refs_iterator.reset(); 1307 } 1308 1309 class ShenandoahCompositeHandshakeClosure : public HandshakeClosure { 1310 HandshakeClosure* _handshake_1; 1311 HandshakeClosure* _handshake_2; 1312 public: 1313 ShenandoahCompositeHandshakeClosure(HandshakeClosure* handshake_1, HandshakeClosure* handshake_2) : 1314 HandshakeClosure(handshake_2->name()), 1315 _handshake_1(handshake_1), _handshake_2(handshake_2) {} 1316 1317 void do_thread(Thread* thread) override { 1318 _handshake_1->do_thread(thread); 1319 _handshake_2->do_thread(thread); 1320 } 1321 }; 1322 1323 void ShenandoahHeap::concurrent_final_roots(HandshakeClosure* handshake_closure) { 1324 { 1325 assert(!is_evacuation_in_progress(), "Should not evacuate for abbreviated or old cycles"); 1326 MutexLocker lock(Threads_lock); 1327 set_gc_state_concurrent(WEAK_ROOTS, false); 1328 } 1329 1330 ShenandoahGCStatePropagator propagator(_gc_state.raw_value()); 1331 Threads::non_java_threads_do(&propagator); 1332 if (handshake_closure == nullptr) { 1333 Handshake::execute(&propagator); 1334 } else { 1335 ShenandoahCompositeHandshakeClosure composite(&propagator, handshake_closure); 1336 Handshake::execute(&composite); 1337 } 1338 } 1339 1340 oop ShenandoahHeap::evacuate_object(oop p, Thread* thread) { 1341 assert(thread == Thread::current(), "Expected thread parameter to be current thread."); 1342 if (ShenandoahThreadLocalData::is_oom_during_evac(thread)) { 1343 // This thread went through the OOM during evac protocol. It is safe to return 1344 // the forward pointer. It must not attempt to evacuate any other objects. 1345 return ShenandoahBarrierSet::resolve_forwarded(p); 1346 } 1347 1348 assert(ShenandoahThreadLocalData::is_evac_allowed(thread), "must be enclosed in oom-evac scope"); 1349 1350 ShenandoahHeapRegion* r = heap_region_containing(p); 1351 assert(!r->is_humongous(), "never evacuate humongous objects"); 1352 1353 ShenandoahAffiliation target_gen = r->affiliation(); 1354 return try_evacuate_object(p, thread, r, target_gen); 1355 } 1356 1357 oop ShenandoahHeap::try_evacuate_object(oop p, Thread* thread, ShenandoahHeapRegion* from_region, 1358 ShenandoahAffiliation target_gen) { 1359 assert(target_gen == YOUNG_GENERATION, "Only expect evacuations to young in this mode"); 1360 assert(from_region->is_young(), "Only expect evacuations from young in this mode"); 1361 bool alloc_from_lab = true; 1362 HeapWord* copy = nullptr; 1363 size_t size = ShenandoahForwarding::size(p); 1364 1365 #ifdef ASSERT 1366 if (ShenandoahOOMDuringEvacALot && 1367 (os::random() & 1) == 0) { // Simulate OOM every ~2nd slow-path call 1368 copy = nullptr; 1369 } else { 1370 #endif 1371 if (UseTLAB) { 1372 copy = allocate_from_gclab(thread, size); 1373 } 1374 if (copy == nullptr) { 1375 // If we failed to allocate in LAB, we'll try a shared allocation. 1376 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_shared_gc(size, target_gen); 1377 copy = allocate_memory(req); 1378 alloc_from_lab = false; 1379 } 1380 #ifdef ASSERT 1381 } 1382 #endif 1383 1384 if (copy == nullptr) { 1385 control_thread()->handle_alloc_failure_evac(size); 1386 1387 _oom_evac_handler.handle_out_of_memory_during_evacuation(); 1388 1389 return ShenandoahBarrierSet::resolve_forwarded(p); 1390 } 1391 1392 // Copy the object: 1393 Copy::aligned_disjoint_words(cast_from_oop<HeapWord*>(p), copy, size); 1394 1395 // Try to install the new forwarding pointer. 1396 oop copy_val = cast_to_oop(copy); 1397 oop result = ShenandoahForwarding::try_update_forwardee(p, copy_val); 1398 if (result == copy_val) { 1399 // Successfully evacuated. Our copy is now the public one! 1400 ContinuationGCSupport::relativize_stack_chunk(copy_val); 1401 shenandoah_assert_correct(nullptr, copy_val); 1402 return copy_val; 1403 } else { 1404 // Failed to evacuate. We need to deal with the object that is left behind. Since this 1405 // new allocation is certainly after TAMS, it will be considered live in the next cycle. 1406 // But if it happens to contain references to evacuated regions, those references would 1407 // not get updated for this stale copy during this cycle, and we will crash while scanning 1408 // it the next cycle. 1409 if (alloc_from_lab) { 1410 // For LAB allocations, it is enough to rollback the allocation ptr. Either the next 1411 // object will overwrite this stale copy, or the filler object on LAB retirement will 1412 // do this. 1413 ShenandoahThreadLocalData::gclab(thread)->undo_allocation(copy, size); 1414 } else { 1415 // For non-LAB allocations, we have no way to retract the allocation, and 1416 // have to explicitly overwrite the copy with the filler object. With that overwrite, 1417 // we have to keep the fwdptr initialized and pointing to our (stale) copy. 1418 assert(size >= ShenandoahHeap::min_fill_size(), "previously allocated object known to be larger than min_size"); 1419 fill_with_object(copy, size); 1420 shenandoah_assert_correct(nullptr, copy_val); 1421 // For non-LAB allocations, the object has already been registered 1422 } 1423 shenandoah_assert_correct(nullptr, result); 1424 return result; 1425 } 1426 } 1427 1428 void ShenandoahHeap::trash_cset_regions() { 1429 ShenandoahHeapLocker locker(lock()); 1430 1431 ShenandoahCollectionSet* set = collection_set(); 1432 ShenandoahHeapRegion* r; 1433 set->clear_current_index(); 1434 while ((r = set->next()) != nullptr) { 1435 r->make_trash(); 1436 } 1437 collection_set()->clear(); 1438 } 1439 1440 void ShenandoahHeap::print_heap_regions_on(outputStream* st) const { 1441 st->print_cr("Heap Regions:"); 1442 st->print_cr("Region state: EU=empty-uncommitted, EC=empty-committed, R=regular, H=humongous start, HP=pinned humongous start"); 1443 st->print_cr(" HC=humongous continuation, CS=collection set, TR=trash, P=pinned, CSP=pinned collection set"); 1444 st->print_cr("BTE=bottom/top/end, TAMS=top-at-mark-start"); 1445 st->print_cr("UWM=update watermark, U=used"); 1446 st->print_cr("T=TLAB allocs, G=GCLAB allocs"); 1447 st->print_cr("S=shared allocs, L=live data"); 1448 st->print_cr("CP=critical pins"); 1449 1450 for (size_t i = 0; i < num_regions(); i++) { 1451 get_region(i)->print_on(st); 1452 } 1453 } 1454 1455 size_t ShenandoahHeap::trash_humongous_region_at(ShenandoahHeapRegion* start) { 1456 assert(start->is_humongous_start(), "reclaim regions starting with the first one"); 1457 1458 oop humongous_obj = cast_to_oop(start->bottom()); 1459 size_t size = humongous_obj->size(); 1460 size_t required_regions = ShenandoahHeapRegion::required_regions(size * HeapWordSize); 1461 size_t index = start->index() + required_regions - 1; 1462 1463 assert(!start->has_live(), "liveness must be zero"); 1464 1465 for(size_t i = 0; i < required_regions; i++) { 1466 // Reclaim from tail. Otherwise, assertion fails when printing region to trace log, 1467 // as it expects that every region belongs to a humongous region starting with a humongous start region. 1468 ShenandoahHeapRegion* region = get_region(index --); 1469 1470 assert(region->is_humongous(), "expect correct humongous start or continuation"); 1471 assert(!region->is_cset(), "Humongous region should not be in collection set"); 1472 1473 region->make_trash_immediate(); 1474 } 1475 return required_regions; 1476 } 1477 1478 class ShenandoahCheckCleanGCLABClosure : public ThreadClosure { 1479 public: 1480 ShenandoahCheckCleanGCLABClosure() {} 1481 void do_thread(Thread* thread) { 1482 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread); 1483 assert(gclab != nullptr, "GCLAB should be initialized for %s", thread->name()); 1484 assert(gclab->words_remaining() == 0, "GCLAB should not need retirement"); 1485 1486 if (ShenandoahHeap::heap()->mode()->is_generational()) { 1487 PLAB* plab = ShenandoahThreadLocalData::plab(thread); 1488 assert(plab != nullptr, "PLAB should be initialized for %s", thread->name()); 1489 assert(plab->words_remaining() == 0, "PLAB should not need retirement"); 1490 } 1491 } 1492 }; 1493 1494 void ShenandoahHeap::labs_make_parsable() { 1495 assert(UseTLAB, "Only call with UseTLAB"); 1496 1497 ShenandoahRetireGCLABClosure cl(false); 1498 1499 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) { 1500 ThreadLocalAllocBuffer& tlab = t->tlab(); 1501 tlab.make_parsable(); 1502 cl.do_thread(t); 1503 } 1504 1505 workers()->threads_do(&cl); 1506 1507 if (safepoint_workers() != nullptr) { 1508 safepoint_workers()->threads_do(&cl); 1509 } 1510 } 1511 1512 void ShenandoahHeap::tlabs_retire(bool resize) { 1513 assert(UseTLAB, "Only call with UseTLAB"); 1514 assert(!resize || ResizeTLAB, "Only call for resize when ResizeTLAB is enabled"); 1515 1516 ThreadLocalAllocStats stats; 1517 1518 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) { 1519 ThreadLocalAllocBuffer& tlab = t->tlab(); 1520 tlab.retire(&stats); 1521 if (resize) { 1522 tlab.resize(); 1523 } 1524 } 1525 1526 stats.publish(); 1527 1528 #ifdef ASSERT 1529 ShenandoahCheckCleanGCLABClosure cl; 1530 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) { 1531 cl.do_thread(t); 1532 } 1533 workers()->threads_do(&cl); 1534 #endif 1535 } 1536 1537 void ShenandoahHeap::gclabs_retire(bool resize) { 1538 assert(UseTLAB, "Only call with UseTLAB"); 1539 assert(!resize || ResizeTLAB, "Only call for resize when ResizeTLAB is enabled"); 1540 1541 ShenandoahRetireGCLABClosure cl(resize); 1542 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) { 1543 cl.do_thread(t); 1544 } 1545 1546 workers()->threads_do(&cl); 1547 1548 if (safepoint_workers() != nullptr) { 1549 safepoint_workers()->threads_do(&cl); 1550 } 1551 } 1552 1553 // Returns size in bytes 1554 size_t ShenandoahHeap::unsafe_max_tlab_alloc(Thread *thread) const { 1555 // Return the max allowed size, and let the allocation path 1556 // figure out the safe size for current allocation. 1557 return ShenandoahHeapRegion::max_tlab_size_bytes(); 1558 } 1559 1560 size_t ShenandoahHeap::max_tlab_size() const { 1561 // Returns size in words 1562 return ShenandoahHeapRegion::max_tlab_size_words(); 1563 } 1564 1565 void ShenandoahHeap::collect_as_vm_thread(GCCause::Cause cause) { 1566 // These requests are ignored because we can't easily have Shenandoah jump into 1567 // a synchronous (degenerated or full) cycle while it is in the middle of a concurrent 1568 // cycle. We _could_ cancel the concurrent cycle and then try to run a cycle directly 1569 // on the VM thread, but this would confuse the control thread mightily and doesn't 1570 // seem worth the trouble. Instead, we will have the caller thread run (and wait for) a 1571 // concurrent cycle in the prologue of the heap inspect/dump operation. This is how 1572 // other concurrent collectors in the JVM handle this scenario as well. 1573 assert(Thread::current()->is_VM_thread(), "Should be the VM thread"); 1574 guarantee(cause == GCCause::_heap_dump || cause == GCCause::_heap_inspection, "Invalid cause"); 1575 } 1576 1577 void ShenandoahHeap::collect(GCCause::Cause cause) { 1578 control_thread()->request_gc(cause); 1579 } 1580 1581 void ShenandoahHeap::do_full_collection(bool clear_all_soft_refs) { 1582 //assert(false, "Shouldn't need to do full collections"); 1583 } 1584 1585 HeapWord* ShenandoahHeap::block_start(const void* addr) const { 1586 ShenandoahHeapRegion* r = heap_region_containing(addr); 1587 if (r != nullptr) { 1588 return r->block_start(addr); 1589 } 1590 return nullptr; 1591 } 1592 1593 bool ShenandoahHeap::block_is_obj(const HeapWord* addr) const { 1594 ShenandoahHeapRegion* r = heap_region_containing(addr); 1595 return r->block_is_obj(addr); 1596 } 1597 1598 bool ShenandoahHeap::print_location(outputStream* st, void* addr) const { 1599 return BlockLocationPrinter<ShenandoahHeap>::print_location(st, addr); 1600 } 1601 1602 void ShenandoahHeap::prepare_for_verify() { 1603 if (SafepointSynchronize::is_at_safepoint() && UseTLAB) { 1604 labs_make_parsable(); 1605 } 1606 } 1607 1608 void ShenandoahHeap::gc_threads_do(ThreadClosure* tcl) const { 1609 if (_shenandoah_policy->is_at_shutdown()) { 1610 return; 1611 } 1612 1613 if (_control_thread != nullptr) { 1614 tcl->do_thread(_control_thread); 1615 } 1616 1617 if (_uncommit_thread != nullptr) { 1618 tcl->do_thread(_uncommit_thread); 1619 } 1620 1621 workers()->threads_do(tcl); 1622 if (_safepoint_workers != nullptr) { 1623 _safepoint_workers->threads_do(tcl); 1624 } 1625 } 1626 1627 void ShenandoahHeap::print_tracing_info() const { 1628 LogTarget(Info, gc, stats) lt; 1629 if (lt.is_enabled()) { 1630 ResourceMark rm; 1631 LogStream ls(lt); 1632 1633 phase_timings()->print_global_on(&ls); 1634 1635 ls.cr(); 1636 ls.cr(); 1637 1638 shenandoah_policy()->print_gc_stats(&ls); 1639 1640 ls.cr(); 1641 ls.cr(); 1642 } 1643 } 1644 1645 void ShenandoahHeap::set_gc_generation(ShenandoahGeneration* generation) { 1646 shenandoah_assert_control_or_vm_thread_at_safepoint(); 1647 _gc_generation = generation; 1648 } 1649 1650 // Active generation may only be set by the VM thread at a safepoint. 1651 void ShenandoahHeap::set_active_generation() { 1652 assert(Thread::current()->is_VM_thread(), "Only the VM Thread"); 1653 assert(SafepointSynchronize::is_at_safepoint(), "Only at a safepoint!"); 1654 assert(_gc_generation != nullptr, "Will set _active_generation to nullptr"); 1655 _active_generation = _gc_generation; 1656 } 1657 1658 void ShenandoahHeap::on_cycle_start(GCCause::Cause cause, ShenandoahGeneration* generation) { 1659 shenandoah_policy()->record_collection_cause(cause); 1660 1661 const GCCause::Cause current = gc_cause(); 1662 assert(current == GCCause::_no_gc, "Over-writing cause: %s, with: %s", 1663 GCCause::to_string(current), GCCause::to_string(cause)); 1664 assert(_gc_generation == nullptr, "Over-writing _gc_generation"); 1665 1666 set_gc_cause(cause); 1667 set_gc_generation(generation); 1668 1669 generation->heuristics()->record_cycle_start(); 1670 } 1671 1672 void ShenandoahHeap::on_cycle_end(ShenandoahGeneration* generation) { 1673 assert(gc_cause() != GCCause::_no_gc, "cause wasn't set"); 1674 assert(_gc_generation != nullptr, "_gc_generation wasn't set"); 1675 1676 generation->heuristics()->record_cycle_end(); 1677 if (mode()->is_generational() && generation->is_global()) { 1678 // If we just completed a GLOBAL GC, claim credit for completion of young-gen and old-gen GC as well 1679 young_generation()->heuristics()->record_cycle_end(); 1680 old_generation()->heuristics()->record_cycle_end(); 1681 } 1682 1683 set_gc_generation(nullptr); 1684 set_gc_cause(GCCause::_no_gc); 1685 } 1686 1687 void ShenandoahHeap::verify(VerifyOption vo) { 1688 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) { 1689 if (ShenandoahVerify) { 1690 verifier()->verify_generic(vo); 1691 } else { 1692 // TODO: Consider allocating verification bitmaps on demand, 1693 // and turn this on unconditionally. 1694 } 1695 } 1696 } 1697 size_t ShenandoahHeap::tlab_capacity(Thread *thr) const { 1698 return _free_set->capacity(); 1699 } 1700 1701 class ObjectIterateScanRootClosure : public BasicOopIterateClosure { 1702 private: 1703 MarkBitMap* _bitmap; 1704 ShenandoahScanObjectStack* _oop_stack; 1705 ShenandoahHeap* const _heap; 1706 ShenandoahMarkingContext* const _marking_context; 1707 1708 template <class T> 1709 void do_oop_work(T* p) { 1710 T o = RawAccess<>::oop_load(p); 1711 if (!CompressedOops::is_null(o)) { 1712 oop obj = CompressedOops::decode_not_null(o); 1713 if (_heap->is_concurrent_weak_root_in_progress() && !_marking_context->is_marked(obj)) { 1714 // There may be dead oops in weak roots in concurrent root phase, do not touch them. 1715 return; 1716 } 1717 obj = ShenandoahBarrierSet::barrier_set()->load_reference_barrier(obj); 1718 1719 assert(oopDesc::is_oop(obj), "must be a valid oop"); 1720 if (!_bitmap->is_marked(obj)) { 1721 _bitmap->mark(obj); 1722 _oop_stack->push(obj); 1723 } 1724 } 1725 } 1726 public: 1727 ObjectIterateScanRootClosure(MarkBitMap* bitmap, ShenandoahScanObjectStack* oop_stack) : 1728 _bitmap(bitmap), _oop_stack(oop_stack), _heap(ShenandoahHeap::heap()), 1729 _marking_context(_heap->marking_context()) {} 1730 void do_oop(oop* p) { do_oop_work(p); } 1731 void do_oop(narrowOop* p) { do_oop_work(p); } 1732 }; 1733 1734 /* 1735 * This is public API, used in preparation of object_iterate(). 1736 * Since we don't do linear scan of heap in object_iterate() (see comment below), we don't 1737 * need to make the heap parsable. For Shenandoah-internal linear heap scans that we can 1738 * control, we call SH::tlabs_retire, SH::gclabs_retire. 1739 */ 1740 void ShenandoahHeap::ensure_parsability(bool retire_tlabs) { 1741 // No-op. 1742 } 1743 1744 /* 1745 * Iterates objects in the heap. This is public API, used for, e.g., heap dumping. 1746 * 1747 * We cannot safely iterate objects by doing a linear scan at random points in time. Linear 1748 * scanning needs to deal with dead objects, which may have dead Klass* pointers (e.g. 1749 * calling oopDesc::size() would crash) or dangling reference fields (crashes) etc. Linear 1750 * scanning therefore depends on having a valid marking bitmap to support it. However, we only 1751 * have a valid marking bitmap after successful marking. In particular, we *don't* have a valid 1752 * marking bitmap during marking, after aborted marking or during/after cleanup (when we just 1753 * wiped the bitmap in preparation for next marking). 1754 * 1755 * For all those reasons, we implement object iteration as a single marking traversal, reporting 1756 * objects as we mark+traverse through the heap, starting from GC roots. JVMTI IterateThroughHeap 1757 * is allowed to report dead objects, but is not required to do so. 1758 */ 1759 void ShenandoahHeap::object_iterate(ObjectClosure* cl) { 1760 // Reset bitmap 1761 if (!prepare_aux_bitmap_for_iteration()) 1762 return; 1763 1764 ShenandoahScanObjectStack oop_stack; 1765 ObjectIterateScanRootClosure oops(&_aux_bit_map, &oop_stack); 1766 // Seed the stack with root scan 1767 scan_roots_for_iteration(&oop_stack, &oops); 1768 1769 // Work through the oop stack to traverse heap 1770 while (! oop_stack.is_empty()) { 1771 oop obj = oop_stack.pop(); 1772 assert(oopDesc::is_oop(obj), "must be a valid oop"); 1773 cl->do_object(obj); 1774 obj->oop_iterate(&oops); 1775 } 1776 1777 assert(oop_stack.is_empty(), "should be empty"); 1778 // Reclaim bitmap 1779 reclaim_aux_bitmap_for_iteration(); 1780 } 1781 1782 bool ShenandoahHeap::prepare_aux_bitmap_for_iteration() { 1783 assert(SafepointSynchronize::is_at_safepoint(), "safe iteration is only available during safepoints"); 1784 1785 if (!_aux_bitmap_region_special && !os::commit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size(), false)) { 1786 log_warning(gc)("Could not commit native memory for auxiliary marking bitmap for heap iteration"); 1787 return false; 1788 } 1789 // Reset bitmap 1790 _aux_bit_map.clear(); 1791 return true; 1792 } 1793 1794 void ShenandoahHeap::scan_roots_for_iteration(ShenandoahScanObjectStack* oop_stack, ObjectIterateScanRootClosure* oops) { 1795 // Process GC roots according to current GC cycle 1796 // This populates the work stack with initial objects 1797 // It is important to relinquish the associated locks before diving 1798 // into heap dumper 1799 uint n_workers = safepoint_workers() != nullptr ? safepoint_workers()->active_workers() : 1; 1800 ShenandoahHeapIterationRootScanner rp(n_workers); 1801 rp.roots_do(oops); 1802 } 1803 1804 void ShenandoahHeap::reclaim_aux_bitmap_for_iteration() { 1805 if (!_aux_bitmap_region_special && !os::uncommit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size())) { 1806 log_warning(gc)("Could not uncommit native memory for auxiliary marking bitmap for heap iteration"); 1807 } 1808 } 1809 1810 // Closure for parallelly iterate objects 1811 class ShenandoahObjectIterateParScanClosure : public BasicOopIterateClosure { 1812 private: 1813 MarkBitMap* _bitmap; 1814 ShenandoahObjToScanQueue* _queue; 1815 ShenandoahHeap* const _heap; 1816 ShenandoahMarkingContext* const _marking_context; 1817 1818 template <class T> 1819 void do_oop_work(T* p) { 1820 T o = RawAccess<>::oop_load(p); 1821 if (!CompressedOops::is_null(o)) { 1822 oop obj = CompressedOops::decode_not_null(o); 1823 if (_heap->is_concurrent_weak_root_in_progress() && !_marking_context->is_marked(obj)) { 1824 // There may be dead oops in weak roots in concurrent root phase, do not touch them. 1825 return; 1826 } 1827 obj = ShenandoahBarrierSet::barrier_set()->load_reference_barrier(obj); 1828 1829 assert(oopDesc::is_oop(obj), "Must be a valid oop"); 1830 if (_bitmap->par_mark(obj)) { 1831 _queue->push(ShenandoahMarkTask(obj)); 1832 } 1833 } 1834 } 1835 public: 1836 ShenandoahObjectIterateParScanClosure(MarkBitMap* bitmap, ShenandoahObjToScanQueue* q) : 1837 _bitmap(bitmap), _queue(q), _heap(ShenandoahHeap::heap()), 1838 _marking_context(_heap->marking_context()) {} 1839 void do_oop(oop* p) { do_oop_work(p); } 1840 void do_oop(narrowOop* p) { do_oop_work(p); } 1841 }; 1842 1843 // Object iterator for parallel heap iteraion. 1844 // The root scanning phase happenes in construction as a preparation of 1845 // parallel marking queues. 1846 // Every worker processes it's own marking queue. work-stealing is used 1847 // to balance workload. 1848 class ShenandoahParallelObjectIterator : public ParallelObjectIteratorImpl { 1849 private: 1850 uint _num_workers; 1851 bool _init_ready; 1852 MarkBitMap* _aux_bit_map; 1853 ShenandoahHeap* _heap; 1854 ShenandoahScanObjectStack _roots_stack; // global roots stack 1855 ShenandoahObjToScanQueueSet* _task_queues; 1856 public: 1857 ShenandoahParallelObjectIterator(uint num_workers, MarkBitMap* bitmap) : 1858 _num_workers(num_workers), 1859 _init_ready(false), 1860 _aux_bit_map(bitmap), 1861 _heap(ShenandoahHeap::heap()) { 1862 // Initialize bitmap 1863 _init_ready = _heap->prepare_aux_bitmap_for_iteration(); 1864 if (!_init_ready) { 1865 return; 1866 } 1867 1868 ObjectIterateScanRootClosure oops(_aux_bit_map, &_roots_stack); 1869 _heap->scan_roots_for_iteration(&_roots_stack, &oops); 1870 1871 _init_ready = prepare_worker_queues(); 1872 } 1873 1874 ~ShenandoahParallelObjectIterator() { 1875 // Reclaim bitmap 1876 _heap->reclaim_aux_bitmap_for_iteration(); 1877 // Reclaim queue for workers 1878 if (_task_queues!= nullptr) { 1879 for (uint i = 0; i < _num_workers; ++i) { 1880 ShenandoahObjToScanQueue* q = _task_queues->queue(i); 1881 if (q != nullptr) { 1882 delete q; 1883 _task_queues->register_queue(i, nullptr); 1884 } 1885 } 1886 delete _task_queues; 1887 _task_queues = nullptr; 1888 } 1889 } 1890 1891 virtual void object_iterate(ObjectClosure* cl, uint worker_id) { 1892 if (_init_ready) { 1893 object_iterate_parallel(cl, worker_id, _task_queues); 1894 } 1895 } 1896 1897 private: 1898 // Divide global root_stack into worker queues 1899 bool prepare_worker_queues() { 1900 _task_queues = new ShenandoahObjToScanQueueSet((int) _num_workers); 1901 // Initialize queues for every workers 1902 for (uint i = 0; i < _num_workers; ++i) { 1903 ShenandoahObjToScanQueue* task_queue = new ShenandoahObjToScanQueue(); 1904 _task_queues->register_queue(i, task_queue); 1905 } 1906 // Divide roots among the workers. Assume that object referencing distribution 1907 // is related with root kind, use round-robin to make every worker have same chance 1908 // to process every kind of roots 1909 size_t roots_num = _roots_stack.size(); 1910 if (roots_num == 0) { 1911 // No work to do 1912 return false; 1913 } 1914 1915 for (uint j = 0; j < roots_num; j++) { 1916 uint stack_id = j % _num_workers; 1917 oop obj = _roots_stack.pop(); 1918 _task_queues->queue(stack_id)->push(ShenandoahMarkTask(obj)); 1919 } 1920 return true; 1921 } 1922 1923 void object_iterate_parallel(ObjectClosure* cl, 1924 uint worker_id, 1925 ShenandoahObjToScanQueueSet* queue_set) { 1926 assert(SafepointSynchronize::is_at_safepoint(), "safe iteration is only available during safepoints"); 1927 assert(queue_set != nullptr, "task queue must not be null"); 1928 1929 ShenandoahObjToScanQueue* q = queue_set->queue(worker_id); 1930 assert(q != nullptr, "object iterate queue must not be null"); 1931 1932 ShenandoahMarkTask t; 1933 ShenandoahObjectIterateParScanClosure oops(_aux_bit_map, q); 1934 1935 // Work through the queue to traverse heap. 1936 // Steal when there is no task in queue. 1937 while (q->pop(t) || queue_set->steal(worker_id, t)) { 1938 oop obj = t.obj(); 1939 assert(oopDesc::is_oop(obj), "must be a valid oop"); 1940 cl->do_object(obj); 1941 obj->oop_iterate(&oops); 1942 } 1943 assert(q->is_empty(), "should be empty"); 1944 } 1945 }; 1946 1947 ParallelObjectIteratorImpl* ShenandoahHeap::parallel_object_iterator(uint workers) { 1948 return new ShenandoahParallelObjectIterator(workers, &_aux_bit_map); 1949 } 1950 1951 // Keep alive an object that was loaded with AS_NO_KEEPALIVE. 1952 void ShenandoahHeap::keep_alive(oop obj) { 1953 if (is_concurrent_mark_in_progress() && (obj != nullptr)) { 1954 ShenandoahBarrierSet::barrier_set()->enqueue(obj); 1955 } 1956 } 1957 1958 void ShenandoahHeap::heap_region_iterate(ShenandoahHeapRegionClosure* blk) const { 1959 for (size_t i = 0; i < num_regions(); i++) { 1960 ShenandoahHeapRegion* current = get_region(i); 1961 blk->heap_region_do(current); 1962 } 1963 } 1964 1965 class ShenandoahParallelHeapRegionTask : public WorkerTask { 1966 private: 1967 ShenandoahHeap* const _heap; 1968 ShenandoahHeapRegionClosure* const _blk; 1969 size_t const _stride; 1970 1971 shenandoah_padding(0); 1972 volatile size_t _index; 1973 shenandoah_padding(1); 1974 1975 public: 1976 ShenandoahParallelHeapRegionTask(ShenandoahHeapRegionClosure* blk, size_t stride) : 1977 WorkerTask("Shenandoah Parallel Region Operation"), 1978 _heap(ShenandoahHeap::heap()), _blk(blk), _stride(stride), _index(0) {} 1979 1980 void work(uint worker_id) { 1981 ShenandoahParallelWorkerSession worker_session(worker_id); 1982 size_t stride = _stride; 1983 1984 size_t max = _heap->num_regions(); 1985 while (Atomic::load(&_index) < max) { 1986 size_t cur = Atomic::fetch_then_add(&_index, stride, memory_order_relaxed); 1987 size_t start = cur; 1988 size_t end = MIN2(cur + stride, max); 1989 if (start >= max) break; 1990 1991 for (size_t i = cur; i < end; i++) { 1992 ShenandoahHeapRegion* current = _heap->get_region(i); 1993 _blk->heap_region_do(current); 1994 } 1995 } 1996 } 1997 }; 1998 1999 void ShenandoahHeap::parallel_heap_region_iterate(ShenandoahHeapRegionClosure* blk) const { 2000 assert(blk->is_thread_safe(), "Only thread-safe closures here"); 2001 const uint active_workers = workers()->active_workers(); 2002 const size_t n_regions = num_regions(); 2003 size_t stride = ShenandoahParallelRegionStride; 2004 if (stride == 0 && active_workers > 1) { 2005 // Automatically derive the stride to balance the work between threads 2006 // evenly. Do not try to split work if below the reasonable threshold. 2007 constexpr size_t threshold = 4096; 2008 stride = n_regions <= threshold ? 2009 threshold : 2010 (n_regions + active_workers - 1) / active_workers; 2011 } 2012 2013 if (n_regions > stride && active_workers > 1) { 2014 ShenandoahParallelHeapRegionTask task(blk, stride); 2015 workers()->run_task(&task); 2016 } else { 2017 heap_region_iterate(blk); 2018 } 2019 } 2020 2021 class ShenandoahRendezvousClosure : public HandshakeClosure { 2022 public: 2023 inline ShenandoahRendezvousClosure(const char* name) : HandshakeClosure(name) {} 2024 inline void do_thread(Thread* thread) {} 2025 }; 2026 2027 void ShenandoahHeap::rendezvous_threads(const char* name) { 2028 ShenandoahRendezvousClosure cl(name); 2029 Handshake::execute(&cl); 2030 } 2031 2032 void ShenandoahHeap::recycle_trash() { 2033 free_set()->recycle_trash(); 2034 } 2035 2036 void ShenandoahHeap::do_class_unloading() { 2037 _unloader.unload(); 2038 if (mode()->is_generational()) { 2039 old_generation()->set_parsable(false); 2040 } 2041 } 2042 2043 void ShenandoahHeap::stw_weak_refs(bool full_gc) { 2044 // Weak refs processing 2045 ShenandoahPhaseTimings::Phase phase = full_gc ? ShenandoahPhaseTimings::full_gc_weakrefs 2046 : ShenandoahPhaseTimings::degen_gc_weakrefs; 2047 ShenandoahTimingsTracker t(phase); 2048 ShenandoahGCWorkerPhase worker_phase(phase); 2049 shenandoah_assert_generations_reconciled(); 2050 gc_generation()->ref_processor()->process_references(phase, workers(), false /* concurrent */); 2051 } 2052 2053 void ShenandoahHeap::prepare_update_heap_references() { 2054 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint"); 2055 2056 // Evacuation is over, no GCLABs are needed anymore. GCLABs are under URWM, so we need to 2057 // make them parsable for update code to work correctly. Plus, we can compute new sizes 2058 // for future GCLABs here. 2059 if (UseTLAB) { 2060 ShenandoahGCPhase phase(ShenandoahPhaseTimings::degen_gc_init_update_refs_manage_gclabs); 2061 gclabs_retire(ResizeTLAB); 2062 } 2063 2064 _update_refs_iterator.reset(); 2065 } 2066 2067 void ShenandoahHeap::propagate_gc_state_to_all_threads() { 2068 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Must be at Shenandoah safepoint"); 2069 if (_gc_state_changed) { 2070 ShenandoahGCStatePropagator propagator(_gc_state.raw_value()); 2071 Threads::threads_do(&propagator); 2072 _gc_state_changed = false; 2073 } 2074 } 2075 2076 void ShenandoahHeap::set_gc_state_at_safepoint(uint mask, bool value) { 2077 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Must be at Shenandoah safepoint"); 2078 _gc_state.set_cond(mask, value); 2079 _gc_state_changed = true; 2080 } 2081 2082 void ShenandoahHeap::set_gc_state_concurrent(uint mask, bool value) { 2083 // Holding the thread lock here assures that any thread created after we change the gc 2084 // state will have the correct state. It also prevents attaching threads from seeing 2085 // an inconsistent state. See ShenandoahBarrierSet::on_thread_attach for reference. Established 2086 // threads will use their thread local copy of the gc state (changed by a handshake, or on a 2087 // safepoint). 2088 assert(Threads_lock->is_locked(), "Must hold thread lock for concurrent gc state change"); 2089 _gc_state.set_cond(mask, value); 2090 } 2091 2092 void ShenandoahHeap::set_concurrent_young_mark_in_progress(bool in_progress) { 2093 uint mask; 2094 assert(!has_forwarded_objects(), "Young marking is not concurrent with evacuation"); 2095 if (!in_progress && is_concurrent_old_mark_in_progress()) { 2096 assert(mode()->is_generational(), "Only generational GC has old marking"); 2097 assert(_gc_state.is_set(MARKING), "concurrent_old_marking_in_progress implies MARKING"); 2098 // If old-marking is in progress when we turn off YOUNG_MARKING, leave MARKING (and OLD_MARKING) on 2099 mask = YOUNG_MARKING; 2100 } else { 2101 mask = MARKING | YOUNG_MARKING; 2102 } 2103 set_gc_state_at_safepoint(mask, in_progress); 2104 manage_satb_barrier(in_progress); 2105 } 2106 2107 void ShenandoahHeap::set_concurrent_old_mark_in_progress(bool in_progress) { 2108 #ifdef ASSERT 2109 // has_forwarded_objects() iff UPDATE_REFS or EVACUATION 2110 bool has_forwarded = has_forwarded_objects(); 2111 bool updating_or_evacuating = _gc_state.is_set(UPDATE_REFS | EVACUATION); 2112 bool evacuating = _gc_state.is_set(EVACUATION); 2113 assert ((has_forwarded == updating_or_evacuating) || (evacuating && !has_forwarded && collection_set()->is_empty()), 2114 "Updating or evacuating iff has forwarded objects, or if evacuation phase is promoting in place without forwarding"); 2115 #endif 2116 if (!in_progress && is_concurrent_young_mark_in_progress()) { 2117 // If young-marking is in progress when we turn off OLD_MARKING, leave MARKING (and YOUNG_MARKING) on 2118 assert(_gc_state.is_set(MARKING), "concurrent_young_marking_in_progress implies MARKING"); 2119 set_gc_state_at_safepoint(OLD_MARKING, in_progress); 2120 } else { 2121 set_gc_state_at_safepoint(MARKING | OLD_MARKING, in_progress); 2122 } 2123 manage_satb_barrier(in_progress); 2124 } 2125 2126 bool ShenandoahHeap::is_prepare_for_old_mark_in_progress() const { 2127 return old_generation()->is_preparing_for_mark(); 2128 } 2129 2130 void ShenandoahHeap::manage_satb_barrier(bool active) { 2131 if (is_concurrent_mark_in_progress()) { 2132 // Ignore request to deactivate barrier while concurrent mark is in progress. 2133 // Do not attempt to re-activate the barrier if it is already active. 2134 if (active && !ShenandoahBarrierSet::satb_mark_queue_set().is_active()) { 2135 ShenandoahBarrierSet::satb_mark_queue_set().set_active_all_threads(active, !active); 2136 } 2137 } else { 2138 // No concurrent marking is in progress so honor request to deactivate, 2139 // but only if the barrier is already active. 2140 if (!active && ShenandoahBarrierSet::satb_mark_queue_set().is_active()) { 2141 ShenandoahBarrierSet::satb_mark_queue_set().set_active_all_threads(active, !active); 2142 } 2143 } 2144 } 2145 2146 void ShenandoahHeap::set_evacuation_in_progress(bool in_progress) { 2147 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Only call this at safepoint"); 2148 set_gc_state_at_safepoint(EVACUATION, in_progress); 2149 } 2150 2151 void ShenandoahHeap::set_concurrent_strong_root_in_progress(bool in_progress) { 2152 if (in_progress) { 2153 _concurrent_strong_root_in_progress.set(); 2154 } else { 2155 _concurrent_strong_root_in_progress.unset(); 2156 } 2157 } 2158 2159 void ShenandoahHeap::set_concurrent_weak_root_in_progress(bool cond) { 2160 set_gc_state_at_safepoint(WEAK_ROOTS, cond); 2161 } 2162 2163 GCTracer* ShenandoahHeap::tracer() { 2164 return shenandoah_policy()->tracer(); 2165 } 2166 2167 size_t ShenandoahHeap::tlab_used(Thread* thread) const { 2168 return _free_set->used(); 2169 } 2170 2171 bool ShenandoahHeap::try_cancel_gc(GCCause::Cause cause) { 2172 const GCCause::Cause prev = _cancelled_gc.xchg(cause); 2173 return prev == GCCause::_no_gc || prev == GCCause::_shenandoah_concurrent_gc; 2174 } 2175 2176 void ShenandoahHeap::cancel_concurrent_mark() { 2177 if (mode()->is_generational()) { 2178 young_generation()->cancel_marking(); 2179 old_generation()->cancel_marking(); 2180 } 2181 2182 global_generation()->cancel_marking(); 2183 2184 ShenandoahBarrierSet::satb_mark_queue_set().abandon_partial_marking(); 2185 } 2186 2187 bool ShenandoahHeap::cancel_gc(GCCause::Cause cause) { 2188 if (try_cancel_gc(cause)) { 2189 FormatBuffer<> msg("Cancelling GC: %s", GCCause::to_string(cause)); 2190 log_info(gc,thread)("%s", msg.buffer()); 2191 Events::log(Thread::current(), "%s", msg.buffer()); 2192 _cancel_requested_time = os::elapsedTime(); 2193 return true; 2194 } 2195 return false; 2196 } 2197 2198 uint ShenandoahHeap::max_workers() { 2199 return _max_workers; 2200 } 2201 2202 void ShenandoahHeap::stop() { 2203 // The shutdown sequence should be able to terminate when GC is running. 2204 2205 // Step 0. Notify policy to disable event recording and prevent visiting gc threads during shutdown 2206 _shenandoah_policy->record_shutdown(); 2207 2208 // Step 1. Stop reporting on gc thread cpu utilization 2209 mmu_tracker()->stop(); 2210 2211 // Step 2. Wait until GC worker exits normally (this will cancel any ongoing GC). 2212 control_thread()->stop(); 2213 2214 // Stop 4. Shutdown uncommit thread. 2215 if (_uncommit_thread != nullptr) { 2216 _uncommit_thread->stop(); 2217 } 2218 } 2219 2220 void ShenandoahHeap::stw_unload_classes(bool full_gc) { 2221 if (!unload_classes()) return; 2222 ClassUnloadingContext ctx(_workers->active_workers(), 2223 true /* unregister_nmethods_during_purge */, 2224 false /* lock_nmethod_free_separately */); 2225 2226 // Unload classes and purge SystemDictionary. 2227 { 2228 ShenandoahPhaseTimings::Phase phase = full_gc ? 2229 ShenandoahPhaseTimings::full_gc_purge_class_unload : 2230 ShenandoahPhaseTimings::degen_gc_purge_class_unload; 2231 ShenandoahIsAliveSelector is_alive; 2232 { 2233 CodeCache::UnlinkingScope scope(is_alive.is_alive_closure()); 2234 ShenandoahGCPhase gc_phase(phase); 2235 ShenandoahGCWorkerPhase worker_phase(phase); 2236 bool unloading_occurred = SystemDictionary::do_unloading(gc_timer()); 2237 2238 // Clean JVMCI metadata handles. 2239 JVMCI_ONLY(JVMCI::do_unloading(unloading_occurred)); 2240 2241 uint num_workers = _workers->active_workers(); 2242 ShenandoahClassUnloadingTask unlink_task(phase, num_workers, unloading_occurred); 2243 _workers->run_task(&unlink_task); 2244 } 2245 // Release unloaded nmethods's memory. 2246 ClassUnloadingContext::context()->purge_and_free_nmethods(); 2247 } 2248 2249 { 2250 ShenandoahGCPhase phase(full_gc ? 2251 ShenandoahPhaseTimings::full_gc_purge_cldg : 2252 ShenandoahPhaseTimings::degen_gc_purge_cldg); 2253 ClassLoaderDataGraph::purge(true /* at_safepoint */); 2254 } 2255 // Resize and verify metaspace 2256 MetaspaceGC::compute_new_size(); 2257 DEBUG_ONLY(MetaspaceUtils::verify();) 2258 } 2259 2260 // Weak roots are either pre-evacuated (final mark) or updated (final update refs), 2261 // so they should not have forwarded oops. 2262 // However, we do need to "null" dead oops in the roots, if can not be done 2263 // in concurrent cycles. 2264 void ShenandoahHeap::stw_process_weak_roots(bool full_gc) { 2265 uint num_workers = _workers->active_workers(); 2266 ShenandoahPhaseTimings::Phase timing_phase = full_gc ? 2267 ShenandoahPhaseTimings::full_gc_purge_weak_par : 2268 ShenandoahPhaseTimings::degen_gc_purge_weak_par; 2269 ShenandoahGCPhase phase(timing_phase); 2270 ShenandoahGCWorkerPhase worker_phase(timing_phase); 2271 // Cleanup weak roots 2272 if (has_forwarded_objects()) { 2273 ShenandoahForwardedIsAliveClosure is_alive; 2274 ShenandoahNonConcUpdateRefsClosure keep_alive; 2275 ShenandoahParallelWeakRootsCleaningTask<ShenandoahForwardedIsAliveClosure, ShenandoahNonConcUpdateRefsClosure> 2276 cleaning_task(timing_phase, &is_alive, &keep_alive, num_workers); 2277 _workers->run_task(&cleaning_task); 2278 } else { 2279 ShenandoahIsAliveClosure is_alive; 2280 #ifdef ASSERT 2281 ShenandoahAssertNotForwardedClosure verify_cl; 2282 ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, ShenandoahAssertNotForwardedClosure> 2283 cleaning_task(timing_phase, &is_alive, &verify_cl, num_workers); 2284 #else 2285 ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, DoNothingClosure> 2286 cleaning_task(timing_phase, &is_alive, &do_nothing_cl, num_workers); 2287 #endif 2288 _workers->run_task(&cleaning_task); 2289 } 2290 } 2291 2292 void ShenandoahHeap::parallel_cleaning(bool full_gc) { 2293 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint"); 2294 assert(is_stw_gc_in_progress(), "Only for Degenerated and Full GC"); 2295 ShenandoahGCPhase phase(full_gc ? 2296 ShenandoahPhaseTimings::full_gc_purge : 2297 ShenandoahPhaseTimings::degen_gc_purge); 2298 stw_weak_refs(full_gc); 2299 stw_process_weak_roots(full_gc); 2300 stw_unload_classes(full_gc); 2301 } 2302 2303 void ShenandoahHeap::set_has_forwarded_objects(bool cond) { 2304 set_gc_state_at_safepoint(HAS_FORWARDED, cond); 2305 } 2306 2307 void ShenandoahHeap::set_unload_classes(bool uc) { 2308 _unload_classes.set_cond(uc); 2309 } 2310 2311 bool ShenandoahHeap::unload_classes() const { 2312 return _unload_classes.is_set(); 2313 } 2314 2315 address ShenandoahHeap::in_cset_fast_test_addr() { 2316 ShenandoahHeap* heap = ShenandoahHeap::heap(); 2317 assert(heap->collection_set() != nullptr, "Sanity"); 2318 return (address) heap->collection_set()->biased_map_address(); 2319 } 2320 2321 void ShenandoahHeap::reset_bytes_allocated_since_gc_start() { 2322 if (mode()->is_generational()) { 2323 young_generation()->reset_bytes_allocated_since_gc_start(); 2324 old_generation()->reset_bytes_allocated_since_gc_start(); 2325 } 2326 2327 global_generation()->reset_bytes_allocated_since_gc_start(); 2328 } 2329 2330 void ShenandoahHeap::set_degenerated_gc_in_progress(bool in_progress) { 2331 _degenerated_gc_in_progress.set_cond(in_progress); 2332 } 2333 2334 void ShenandoahHeap::set_full_gc_in_progress(bool in_progress) { 2335 _full_gc_in_progress.set_cond(in_progress); 2336 } 2337 2338 void ShenandoahHeap::set_full_gc_move_in_progress(bool in_progress) { 2339 assert (is_full_gc_in_progress(), "should be"); 2340 _full_gc_move_in_progress.set_cond(in_progress); 2341 } 2342 2343 void ShenandoahHeap::set_update_refs_in_progress(bool in_progress) { 2344 set_gc_state_at_safepoint(UPDATE_REFS, in_progress); 2345 } 2346 2347 void ShenandoahHeap::register_nmethod(nmethod* nm) { 2348 ShenandoahCodeRoots::register_nmethod(nm); 2349 } 2350 2351 void ShenandoahHeap::unregister_nmethod(nmethod* nm) { 2352 ShenandoahCodeRoots::unregister_nmethod(nm); 2353 } 2354 2355 void ShenandoahHeap::pin_object(JavaThread* thr, oop o) { 2356 heap_region_containing(o)->record_pin(); 2357 } 2358 2359 void ShenandoahHeap::unpin_object(JavaThread* thr, oop o) { 2360 ShenandoahHeapRegion* r = heap_region_containing(o); 2361 assert(r != nullptr, "Sanity"); 2362 assert(r->pin_count() > 0, "Region %zu should have non-zero pins", r->index()); 2363 r->record_unpin(); 2364 } 2365 2366 void ShenandoahHeap::sync_pinned_region_status() { 2367 ShenandoahHeapLocker locker(lock()); 2368 2369 for (size_t i = 0; i < num_regions(); i++) { 2370 ShenandoahHeapRegion *r = get_region(i); 2371 if (r->is_active()) { 2372 if (r->is_pinned()) { 2373 if (r->pin_count() == 0) { 2374 r->make_unpinned(); 2375 } 2376 } else { 2377 if (r->pin_count() > 0) { 2378 r->make_pinned(); 2379 } 2380 } 2381 } 2382 } 2383 2384 assert_pinned_region_status(); 2385 } 2386 2387 #ifdef ASSERT 2388 void ShenandoahHeap::assert_pinned_region_status() { 2389 for (size_t i = 0; i < num_regions(); i++) { 2390 ShenandoahHeapRegion* r = get_region(i); 2391 shenandoah_assert_generations_reconciled(); 2392 if (gc_generation()->contains(r)) { 2393 assert((r->is_pinned() && r->pin_count() > 0) || (!r->is_pinned() && r->pin_count() == 0), 2394 "Region %zu pinning status is inconsistent", i); 2395 } 2396 } 2397 } 2398 #endif 2399 2400 ConcurrentGCTimer* ShenandoahHeap::gc_timer() const { 2401 return _gc_timer; 2402 } 2403 2404 void ShenandoahHeap::prepare_concurrent_roots() { 2405 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint"); 2406 assert(!is_stw_gc_in_progress(), "Only concurrent GC"); 2407 set_concurrent_strong_root_in_progress(!collection_set()->is_empty()); 2408 set_concurrent_weak_root_in_progress(true); 2409 if (unload_classes()) { 2410 _unloader.prepare(); 2411 } 2412 } 2413 2414 void ShenandoahHeap::finish_concurrent_roots() { 2415 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint"); 2416 assert(!is_stw_gc_in_progress(), "Only concurrent GC"); 2417 if (unload_classes()) { 2418 _unloader.finish(); 2419 } 2420 } 2421 2422 #ifdef ASSERT 2423 void ShenandoahHeap::assert_gc_workers(uint nworkers) { 2424 assert(nworkers > 0 && nworkers <= max_workers(), "Sanity"); 2425 2426 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) { 2427 // Use ParallelGCThreads inside safepoints 2428 assert(nworkers == ParallelGCThreads, "Use ParallelGCThreads (%u) within safepoint, not %u", 2429 ParallelGCThreads, nworkers); 2430 } else { 2431 // Use ConcGCThreads outside safepoints 2432 assert(nworkers == ConcGCThreads, "Use ConcGCThreads (%u) outside safepoints, %u", 2433 ConcGCThreads, nworkers); 2434 } 2435 } 2436 #endif 2437 2438 ShenandoahVerifier* ShenandoahHeap::verifier() { 2439 guarantee(ShenandoahVerify, "Should be enabled"); 2440 assert (_verifier != nullptr, "sanity"); 2441 return _verifier; 2442 } 2443 2444 template<bool CONCURRENT> 2445 class ShenandoahUpdateHeapRefsTask : public WorkerTask { 2446 private: 2447 ShenandoahHeap* _heap; 2448 ShenandoahRegionIterator* _regions; 2449 public: 2450 explicit ShenandoahUpdateHeapRefsTask(ShenandoahRegionIterator* regions) : 2451 WorkerTask("Shenandoah Update References"), 2452 _heap(ShenandoahHeap::heap()), 2453 _regions(regions) { 2454 } 2455 2456 void work(uint worker_id) { 2457 if (CONCURRENT) { 2458 ShenandoahConcurrentWorkerSession worker_session(worker_id); 2459 ShenandoahSuspendibleThreadSetJoiner stsj; 2460 do_work<ShenandoahConcUpdateRefsClosure>(worker_id); 2461 } else { 2462 ShenandoahParallelWorkerSession worker_session(worker_id); 2463 do_work<ShenandoahNonConcUpdateRefsClosure>(worker_id); 2464 } 2465 } 2466 2467 private: 2468 template<class T> 2469 void do_work(uint worker_id) { 2470 if (CONCURRENT && (worker_id == 0)) { 2471 // We ask the first worker to replenish the Mutator free set by moving regions previously reserved to hold the 2472 // results of evacuation. These reserves are no longer necessary because evacuation has completed. 2473 size_t cset_regions = _heap->collection_set()->count(); 2474 2475 // Now that evacuation is done, we can reassign any regions that had been reserved to hold the results of evacuation 2476 // to the mutator free set. At the end of GC, we will have cset_regions newly evacuated fully empty regions from 2477 // which we will be able to replenish the Collector free set and the OldCollector free set in preparation for the 2478 // next GC cycle. 2479 _heap->free_set()->move_regions_from_collector_to_mutator(cset_regions); 2480 } 2481 // If !CONCURRENT, there's no value in expanding Mutator free set 2482 T cl; 2483 ShenandoahHeapRegion* r = _regions->next(); 2484 while (r != nullptr) { 2485 HeapWord* update_watermark = r->get_update_watermark(); 2486 assert (update_watermark >= r->bottom(), "sanity"); 2487 if (r->is_active() && !r->is_cset()) { 2488 _heap->marked_object_oop_iterate(r, &cl, update_watermark); 2489 if (ShenandoahPacing) { 2490 _heap->pacer()->report_update_refs(pointer_delta(update_watermark, r->bottom())); 2491 } 2492 } 2493 if (_heap->check_cancelled_gc_and_yield(CONCURRENT)) { 2494 return; 2495 } 2496 r = _regions->next(); 2497 } 2498 } 2499 }; 2500 2501 void ShenandoahHeap::update_heap_references(bool concurrent) { 2502 assert(!is_full_gc_in_progress(), "Only for concurrent and degenerated GC"); 2503 2504 if (concurrent) { 2505 ShenandoahUpdateHeapRefsTask<true> task(&_update_refs_iterator); 2506 workers()->run_task(&task); 2507 } else { 2508 ShenandoahUpdateHeapRefsTask<false> task(&_update_refs_iterator); 2509 workers()->run_task(&task); 2510 } 2511 } 2512 2513 void ShenandoahHeap::update_heap_region_states(bool concurrent) { 2514 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint"); 2515 assert(!is_full_gc_in_progress(), "Only for concurrent and degenerated GC"); 2516 2517 { 2518 ShenandoahGCPhase phase(concurrent ? 2519 ShenandoahPhaseTimings::final_update_refs_update_region_states : 2520 ShenandoahPhaseTimings::degen_gc_final_update_refs_update_region_states); 2521 2522 final_update_refs_update_region_states(); 2523 2524 assert_pinned_region_status(); 2525 } 2526 2527 { 2528 ShenandoahGCPhase phase(concurrent ? 2529 ShenandoahPhaseTimings::final_update_refs_trash_cset : 2530 ShenandoahPhaseTimings::degen_gc_final_update_refs_trash_cset); 2531 trash_cset_regions(); 2532 } 2533 } 2534 2535 void ShenandoahHeap::final_update_refs_update_region_states() { 2536 ShenandoahSynchronizePinnedRegionStates cl; 2537 parallel_heap_region_iterate(&cl); 2538 } 2539 2540 void ShenandoahHeap::rebuild_free_set(bool concurrent) { 2541 ShenandoahGCPhase phase(concurrent ? 2542 ShenandoahPhaseTimings::final_update_refs_rebuild_freeset : 2543 ShenandoahPhaseTimings::degen_gc_final_update_refs_rebuild_freeset); 2544 ShenandoahHeapLocker locker(lock()); 2545 size_t young_cset_regions, old_cset_regions; 2546 size_t first_old_region, last_old_region, old_region_count; 2547 _free_set->prepare_to_rebuild(young_cset_regions, old_cset_regions, first_old_region, last_old_region, old_region_count); 2548 // If there are no old regions, first_old_region will be greater than last_old_region 2549 assert((first_old_region > last_old_region) || 2550 ((last_old_region + 1 - first_old_region >= old_region_count) && 2551 get_region(first_old_region)->is_old() && get_region(last_old_region)->is_old()), 2552 "sanity: old_region_count: %zu, first_old_region: %zu, last_old_region: %zu", 2553 old_region_count, first_old_region, last_old_region); 2554 2555 if (mode()->is_generational()) { 2556 #ifdef ASSERT 2557 if (ShenandoahVerify) { 2558 verifier()->verify_before_rebuilding_free_set(); 2559 } 2560 #endif 2561 2562 // The computation of bytes_of_allocation_runway_before_gc_trigger is quite conservative so consider all of this 2563 // available for transfer to old. Note that transfer of humongous regions does not impact available. 2564 ShenandoahGenerationalHeap* gen_heap = ShenandoahGenerationalHeap::heap(); 2565 size_t allocation_runway = gen_heap->young_generation()->heuristics()->bytes_of_allocation_runway_before_gc_trigger(young_cset_regions); 2566 gen_heap->compute_old_generation_balance(allocation_runway, old_cset_regions); 2567 2568 // Total old_available may have been expanded to hold anticipated promotions. We trigger if the fragmented available 2569 // memory represents more than 16 regions worth of data. Note that fragmentation may increase when we promote regular 2570 // regions in place when many of these regular regions have an abundant amount of available memory within them. Fragmentation 2571 // will decrease as promote-by-copy consumes the available memory within these partially consumed regions. 2572 // 2573 // We consider old-gen to have excessive fragmentation if more than 12.5% of old-gen is free memory that resides 2574 // within partially consumed regions of memory. 2575 } 2576 // Rebuild free set based on adjusted generation sizes. 2577 _free_set->finish_rebuild(young_cset_regions, old_cset_regions, old_region_count); 2578 2579 if (mode()->is_generational()) { 2580 ShenandoahGenerationalHeap* gen_heap = ShenandoahGenerationalHeap::heap(); 2581 ShenandoahOldGeneration* old_gen = gen_heap->old_generation(); 2582 old_gen->heuristics()->evaluate_triggers(first_old_region, last_old_region, old_region_count, num_regions()); 2583 } 2584 } 2585 2586 bool ShenandoahHeap::is_bitmap_slice_committed(ShenandoahHeapRegion* r, bool skip_self) { 2587 size_t slice = r->index() / _bitmap_regions_per_slice; 2588 2589 size_t regions_from = _bitmap_regions_per_slice * slice; 2590 size_t regions_to = MIN2(num_regions(), _bitmap_regions_per_slice * (slice + 1)); 2591 for (size_t g = regions_from; g < regions_to; g++) { 2592 assert (g / _bitmap_regions_per_slice == slice, "same slice"); 2593 if (skip_self && g == r->index()) continue; 2594 if (get_region(g)->is_committed()) { 2595 return true; 2596 } 2597 } 2598 return false; 2599 } 2600 2601 bool ShenandoahHeap::commit_bitmap_slice(ShenandoahHeapRegion* r) { 2602 shenandoah_assert_heaplocked(); 2603 2604 // Bitmaps in special regions do not need commits 2605 if (_bitmap_region_special) { 2606 return true; 2607 } 2608 2609 if (is_bitmap_slice_committed(r, true)) { 2610 // Some other region from the group is already committed, meaning the bitmap 2611 // slice is already committed, we exit right away. 2612 return true; 2613 } 2614 2615 // Commit the bitmap slice: 2616 size_t slice = r->index() / _bitmap_regions_per_slice; 2617 size_t off = _bitmap_bytes_per_slice * slice; 2618 size_t len = _bitmap_bytes_per_slice; 2619 char* start = (char*) _bitmap_region.start() + off; 2620 2621 if (!os::commit_memory(start, len, false)) { 2622 return false; 2623 } 2624 2625 if (AlwaysPreTouch) { 2626 os::pretouch_memory(start, start + len, _pretouch_bitmap_page_size); 2627 } 2628 2629 return true; 2630 } 2631 2632 bool ShenandoahHeap::uncommit_bitmap_slice(ShenandoahHeapRegion *r) { 2633 shenandoah_assert_heaplocked(); 2634 2635 // Bitmaps in special regions do not need uncommits 2636 if (_bitmap_region_special) { 2637 return true; 2638 } 2639 2640 if (is_bitmap_slice_committed(r, true)) { 2641 // Some other region from the group is still committed, meaning the bitmap 2642 // slice should stay committed, exit right away. 2643 return true; 2644 } 2645 2646 // Uncommit the bitmap slice: 2647 size_t slice = r->index() / _bitmap_regions_per_slice; 2648 size_t off = _bitmap_bytes_per_slice * slice; 2649 size_t len = _bitmap_bytes_per_slice; 2650 if (!os::uncommit_memory((char*)_bitmap_region.start() + off, len)) { 2651 return false; 2652 } 2653 return true; 2654 } 2655 2656 void ShenandoahHeap::forbid_uncommit() { 2657 if (_uncommit_thread != nullptr) { 2658 _uncommit_thread->forbid_uncommit(); 2659 } 2660 } 2661 2662 void ShenandoahHeap::allow_uncommit() { 2663 if (_uncommit_thread != nullptr) { 2664 _uncommit_thread->allow_uncommit(); 2665 } 2666 } 2667 2668 #ifdef ASSERT 2669 bool ShenandoahHeap::is_uncommit_in_progress() { 2670 if (_uncommit_thread != nullptr) { 2671 return _uncommit_thread->is_uncommit_in_progress(); 2672 } 2673 return false; 2674 } 2675 #endif 2676 2677 void ShenandoahHeap::safepoint_synchronize_begin() { 2678 StackWatermarkSet::safepoint_synchronize_begin(); 2679 SuspendibleThreadSet::synchronize(); 2680 } 2681 2682 void ShenandoahHeap::safepoint_synchronize_end() { 2683 SuspendibleThreadSet::desynchronize(); 2684 } 2685 2686 void ShenandoahHeap::try_inject_alloc_failure() { 2687 if (ShenandoahAllocFailureALot && !cancelled_gc() && ((os::random() % 1000) > 950)) { 2688 _inject_alloc_failure.set(); 2689 os::naked_short_sleep(1); 2690 if (cancelled_gc()) { 2691 log_info(gc)("Allocation failure was successfully injected"); 2692 } 2693 } 2694 } 2695 2696 bool ShenandoahHeap::should_inject_alloc_failure() { 2697 return _inject_alloc_failure.is_set() && _inject_alloc_failure.try_unset(); 2698 } 2699 2700 void ShenandoahHeap::initialize_serviceability() { 2701 _memory_pool = new ShenandoahMemoryPool(this); 2702 _cycle_memory_manager.add_pool(_memory_pool); 2703 _stw_memory_manager.add_pool(_memory_pool); 2704 } 2705 2706 GrowableArray<GCMemoryManager*> ShenandoahHeap::memory_managers() { 2707 GrowableArray<GCMemoryManager*> memory_managers(2); 2708 memory_managers.append(&_cycle_memory_manager); 2709 memory_managers.append(&_stw_memory_manager); 2710 return memory_managers; 2711 } 2712 2713 GrowableArray<MemoryPool*> ShenandoahHeap::memory_pools() { 2714 GrowableArray<MemoryPool*> memory_pools(1); 2715 memory_pools.append(_memory_pool); 2716 return memory_pools; 2717 } 2718 2719 MemoryUsage ShenandoahHeap::memory_usage() { 2720 return MemoryUsage(_initial_size, used(), committed(), max_capacity()); 2721 } 2722 2723 ShenandoahRegionIterator::ShenandoahRegionIterator() : 2724 _heap(ShenandoahHeap::heap()), 2725 _index(0) {} 2726 2727 ShenandoahRegionIterator::ShenandoahRegionIterator(ShenandoahHeap* heap) : 2728 _heap(heap), 2729 _index(0) {} 2730 2731 void ShenandoahRegionIterator::reset() { 2732 _index = 0; 2733 } 2734 2735 bool ShenandoahRegionIterator::has_next() const { 2736 return _index < _heap->num_regions(); 2737 } 2738 2739 char ShenandoahHeap::gc_state() const { 2740 return _gc_state.raw_value(); 2741 } 2742 2743 bool ShenandoahHeap::is_gc_state(GCState state) const { 2744 // If the global gc state has been changed, but hasn't yet been propagated to all threads, then 2745 // the global gc state is the correct value. Once the gc state has been synchronized with all threads, 2746 // _gc_state_changed will be toggled to false and we need to use the thread local state. 2747 return _gc_state_changed ? _gc_state.is_set(state) : ShenandoahThreadLocalData::is_gc_state(state); 2748 } 2749 2750 2751 ShenandoahLiveData* ShenandoahHeap::get_liveness_cache(uint worker_id) { 2752 #ifdef ASSERT 2753 assert(_liveness_cache != nullptr, "sanity"); 2754 assert(worker_id < _max_workers, "sanity"); 2755 for (uint i = 0; i < num_regions(); i++) { 2756 assert(_liveness_cache[worker_id][i] == 0, "liveness cache should be empty"); 2757 } 2758 #endif 2759 return _liveness_cache[worker_id]; 2760 } 2761 2762 void ShenandoahHeap::flush_liveness_cache(uint worker_id) { 2763 assert(worker_id < _max_workers, "sanity"); 2764 assert(_liveness_cache != nullptr, "sanity"); 2765 ShenandoahLiveData* ld = _liveness_cache[worker_id]; 2766 for (uint i = 0; i < num_regions(); i++) { 2767 ShenandoahLiveData live = ld[i]; 2768 if (live > 0) { 2769 ShenandoahHeapRegion* r = get_region(i); 2770 r->increase_live_data_gc_words(live); 2771 ld[i] = 0; 2772 } 2773 } 2774 } 2775 2776 bool ShenandoahHeap::requires_barriers(stackChunkOop obj) const { 2777 if (is_idle()) return false; 2778 2779 // Objects allocated after marking start are implicitly alive, don't need any barriers during 2780 // marking phase. 2781 if (is_concurrent_mark_in_progress() && 2782 !marking_context()->allocated_after_mark_start(obj)) { 2783 return true; 2784 } 2785 2786 // Can not guarantee obj is deeply good. 2787 if (has_forwarded_objects()) { 2788 return true; 2789 } 2790 2791 return false; 2792 } 2793 2794 HeapWord* ShenandoahHeap::allocate_loaded_archive_space(size_t size) { 2795 #if INCLUDE_CDS_JAVA_HEAP 2796 // CDS wants a continuous memory range to load a bunch of objects. 2797 // This effectively bypasses normal allocation paths, and requires 2798 // a bit of massaging to unbreak GC invariants. 2799 2800 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_shared(size); 2801 2802 // Easy case: a single regular region, no further adjustments needed. 2803 if (!ShenandoahHeapRegion::requires_humongous(size)) { 2804 return allocate_memory(req); 2805 } 2806 2807 // Hard case: the requested size would cause a humongous allocation. 2808 // We need to make sure it looks like regular allocation to the rest of GC. 2809 2810 // CDS code would guarantee no objects straddle multiple regions, as long as 2811 // regions are as large as MIN_GC_REGION_ALIGNMENT. It is impractical at this 2812 // point to deal with case when Shenandoah runs with smaller regions. 2813 // TODO: This check can be dropped once MIN_GC_REGION_ALIGNMENT agrees more with Shenandoah. 2814 if (ShenandoahHeapRegion::region_size_bytes() < ArchiveHeapWriter::MIN_GC_REGION_ALIGNMENT) { 2815 return nullptr; 2816 } 2817 2818 HeapWord* mem = allocate_memory(req); 2819 size_t start_idx = heap_region_index_containing(mem); 2820 size_t num_regions = ShenandoahHeapRegion::required_regions(size * HeapWordSize); 2821 2822 // Flip humongous -> regular. 2823 { 2824 ShenandoahHeapLocker locker(lock(), false); 2825 for (size_t c = start_idx; c < start_idx + num_regions; c++) { 2826 get_region(c)->make_regular_bypass(); 2827 } 2828 } 2829 2830 return mem; 2831 #else 2832 assert(false, "Archive heap loader should not be available, should not be here"); 2833 return nullptr; 2834 #endif // INCLUDE_CDS_JAVA_HEAP 2835 } 2836 2837 void ShenandoahHeap::complete_loaded_archive_space(MemRegion archive_space) { 2838 // Nothing to do here, except checking that heap looks fine. 2839 #ifdef ASSERT 2840 HeapWord* start = archive_space.start(); 2841 HeapWord* end = archive_space.end(); 2842 2843 // No unclaimed space between the objects. 2844 // Objects are properly allocated in correct regions. 2845 HeapWord* cur = start; 2846 while (cur < end) { 2847 oop oop = cast_to_oop(cur); 2848 shenandoah_assert_in_correct_region(nullptr, oop); 2849 cur += oop->size(); 2850 } 2851 2852 // No unclaimed tail at the end of archive space. 2853 assert(cur == end, 2854 "Archive space should be fully used: " PTR_FORMAT " " PTR_FORMAT, 2855 p2i(cur), p2i(end)); 2856 2857 // Region bounds are good. 2858 ShenandoahHeapRegion* begin_reg = heap_region_containing(start); 2859 ShenandoahHeapRegion* end_reg = heap_region_containing(end); 2860 assert(begin_reg->is_regular(), "Must be"); 2861 assert(end_reg->is_regular(), "Must be"); 2862 assert(begin_reg->bottom() == start, 2863 "Must agree: archive-space-start: " PTR_FORMAT ", begin-region-bottom: " PTR_FORMAT, 2864 p2i(start), p2i(begin_reg->bottom())); 2865 assert(end_reg->top() == end, 2866 "Must agree: archive-space-end: " PTR_FORMAT ", end-region-top: " PTR_FORMAT, 2867 p2i(end), p2i(end_reg->top())); 2868 #endif 2869 } 2870 2871 ShenandoahGeneration* ShenandoahHeap::generation_for(ShenandoahAffiliation affiliation) const { 2872 if (!mode()->is_generational()) { 2873 return global_generation(); 2874 } else if (affiliation == YOUNG_GENERATION) { 2875 return young_generation(); 2876 } else if (affiliation == OLD_GENERATION) { 2877 return old_generation(); 2878 } 2879 2880 ShouldNotReachHere(); 2881 return nullptr; 2882 } 2883 2884 void ShenandoahHeap::log_heap_status(const char* msg) const { 2885 if (mode()->is_generational()) { 2886 young_generation()->log_status(msg); 2887 old_generation()->log_status(msg); 2888 } else { 2889 global_generation()->log_status(msg); 2890 } 2891 }