1 /* 2 * Copyright (c) 2013, 2020, Red Hat, Inc. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "memory/allocation.hpp" 27 #include "memory/universe.hpp" 28 29 #include "gc/shared/gcArguments.hpp" 30 #include "gc/shared/gcTimer.hpp" 31 #include "gc/shared/gcTraceTime.inline.hpp" 32 #include "gc/shared/locationPrinter.inline.hpp" 33 #include "gc/shared/memAllocator.hpp" 34 #include "gc/shared/oopStorageSet.hpp" 35 #include "gc/shared/plab.hpp" 36 37 #include "gc/shenandoah/shenandoahBarrierSet.hpp" 38 #include "gc/shenandoah/shenandoahClosures.inline.hpp" 39 #include "gc/shenandoah/shenandoahCollectionSet.hpp" 40 #include "gc/shenandoah/shenandoahCollectorPolicy.hpp" 41 #include "gc/shenandoah/shenandoahConcurrentMark.inline.hpp" 42 #include "gc/shenandoah/shenandoahConcurrentRoots.hpp" 43 #include "gc/shenandoah/shenandoahControlThread.hpp" 44 #include "gc/shenandoah/shenandoahFreeSet.hpp" 45 #include "gc/shenandoah/shenandoahPhaseTimings.hpp" 46 #include "gc/shenandoah/shenandoahHeap.inline.hpp" 47 #include "gc/shenandoah/shenandoahHeapRegion.inline.hpp" 48 #include "gc/shenandoah/shenandoahHeapRegionSet.hpp" 49 #include "gc/shenandoah/shenandoahInitLogger.hpp" 50 #include "gc/shenandoah/shenandoahMarkCompact.hpp" 51 #include "gc/shenandoah/shenandoahMarkingContext.inline.hpp" 52 #include "gc/shenandoah/shenandoahMemoryPool.hpp" 53 #include "gc/shenandoah/shenandoahMetrics.hpp" 54 #include "gc/shenandoah/shenandoahMonitoringSupport.hpp" 55 #include "gc/shenandoah/shenandoahOopClosures.inline.hpp" 56 #include "gc/shenandoah/shenandoahPacer.inline.hpp" 57 #include "gc/shenandoah/shenandoahPadding.hpp" 58 #include "gc/shenandoah/shenandoahParallelCleaning.inline.hpp" 59 #include "gc/shenandoah/shenandoahRootProcessor.inline.hpp" 60 #include "gc/shenandoah/shenandoahStringDedup.hpp" 61 #include "gc/shenandoah/shenandoahTaskqueue.hpp" 62 #include "gc/shenandoah/shenandoahUtils.hpp" 63 #include "gc/shenandoah/shenandoahVerifier.hpp" 64 #include "gc/shenandoah/shenandoahCodeRoots.hpp" 65 #include "gc/shenandoah/shenandoahVMOperations.hpp" 66 #include "gc/shenandoah/shenandoahWorkGroup.hpp" 67 #include "gc/shenandoah/shenandoahWorkerPolicy.hpp" 68 #include "gc/shenandoah/mode/shenandoahIUMode.hpp" 69 #include "gc/shenandoah/mode/shenandoahPassiveMode.hpp" 70 #include "gc/shenandoah/mode/shenandoahSATBMode.hpp" 71 #if INCLUDE_JFR 72 #include "gc/shenandoah/shenandoahJfrSupport.hpp" 73 #endif 74 75 #include "memory/metaspace.hpp" 76 #include "oops/compressedOops.inline.hpp" 77 #include "runtime/atomic.hpp" 78 #include "runtime/globals.hpp" 79 #include "runtime/interfaceSupport.inline.hpp" 80 #include "runtime/orderAccess.hpp" 81 #include "runtime/safepointMechanism.hpp" 82 #include "runtime/vmThread.hpp" 83 #include "services/mallocTracker.hpp" 84 #include "utilities/powerOfTwo.hpp" 85 86 ShenandoahHeap* ShenandoahHeap::_heap = NULL; 87 88 #ifdef ASSERT 89 template <class T> 90 void ShenandoahAssertToSpaceClosure::do_oop_work(T* p) { 91 T o = RawAccess<>::oop_load(p); 92 if (! CompressedOops::is_null(o)) { 93 oop obj = CompressedOops::decode_not_null(o); 94 shenandoah_assert_not_forwarded(p, obj); 95 } 96 } 97 98 void ShenandoahAssertToSpaceClosure::do_oop(narrowOop* p) { do_oop_work(p); } 99 void ShenandoahAssertToSpaceClosure::do_oop(oop* p) { do_oop_work(p); } 100 #endif 101 102 class ShenandoahPretouchHeapTask : public AbstractGangTask { 103 private: 104 ShenandoahRegionIterator _regions; 105 const size_t _page_size; 106 public: 107 ShenandoahPretouchHeapTask(size_t page_size) : 108 AbstractGangTask("Shenandoah Pretouch Heap"), 109 _page_size(page_size) {} 110 111 virtual void work(uint worker_id) { 112 ShenandoahHeapRegion* r = _regions.next(); 113 while (r != NULL) { 114 if (r->is_committed()) { 115 os::pretouch_memory(r->bottom(), r->end(), _page_size); 116 } 117 r = _regions.next(); 118 } 119 } 120 }; 121 122 class ShenandoahPretouchBitmapTask : public AbstractGangTask { 123 private: 124 ShenandoahRegionIterator _regions; 125 char* _bitmap_base; 126 const size_t _bitmap_size; 127 const size_t _page_size; 128 public: 129 ShenandoahPretouchBitmapTask(char* bitmap_base, size_t bitmap_size, size_t page_size) : 130 AbstractGangTask("Shenandoah Pretouch Bitmap"), 131 _bitmap_base(bitmap_base), 132 _bitmap_size(bitmap_size), 133 _page_size(page_size) {} 134 135 virtual void work(uint worker_id) { 136 ShenandoahHeapRegion* r = _regions.next(); 137 while (r != NULL) { 138 size_t start = r->index() * ShenandoahHeapRegion::region_size_bytes() / MarkBitMap::heap_map_factor(); 139 size_t end = (r->index() + 1) * ShenandoahHeapRegion::region_size_bytes() / MarkBitMap::heap_map_factor(); 140 assert (end <= _bitmap_size, "end is sane: " SIZE_FORMAT " < " SIZE_FORMAT, end, _bitmap_size); 141 142 if (r->is_committed()) { 143 os::pretouch_memory(_bitmap_base + start, _bitmap_base + end, _page_size); 144 } 145 146 r = _regions.next(); 147 } 148 } 149 }; 150 151 jint ShenandoahHeap::initialize() { 152 // 153 // Figure out heap sizing 154 // 155 156 size_t init_byte_size = InitialHeapSize; 157 size_t min_byte_size = MinHeapSize; 158 size_t max_byte_size = MaxHeapSize; 159 size_t heap_alignment = HeapAlignment; 160 161 size_t reg_size_bytes = ShenandoahHeapRegion::region_size_bytes(); 162 163 Universe::check_alignment(max_byte_size, reg_size_bytes, "Shenandoah heap"); 164 Universe::check_alignment(init_byte_size, reg_size_bytes, "Shenandoah heap"); 165 166 _num_regions = ShenandoahHeapRegion::region_count(); 167 168 // Now we know the number of regions, initialize the heuristics. 169 initialize_heuristics(); 170 171 size_t num_committed_regions = init_byte_size / reg_size_bytes; 172 num_committed_regions = MIN2(num_committed_regions, _num_regions); 173 assert(num_committed_regions <= _num_regions, "sanity"); 174 _initial_size = num_committed_regions * reg_size_bytes; 175 176 size_t num_min_regions = min_byte_size / reg_size_bytes; 177 num_min_regions = MIN2(num_min_regions, _num_regions); 178 assert(num_min_regions <= _num_regions, "sanity"); 179 _minimum_size = num_min_regions * reg_size_bytes; 180 181 _committed = _initial_size; 182 183 size_t heap_page_size = UseLargePages ? (size_t)os::large_page_size() : (size_t)os::vm_page_size(); 184 size_t bitmap_page_size = UseLargePages ? (size_t)os::large_page_size() : (size_t)os::vm_page_size(); 185 size_t region_page_size = UseLargePages ? (size_t)os::large_page_size() : (size_t)os::vm_page_size(); 186 187 // 188 // Reserve and commit memory for heap 189 // 190 191 ReservedHeapSpace heap_rs = Universe::reserve_heap(max_byte_size, heap_alignment); 192 initialize_reserved_region(heap_rs); 193 _heap_region = MemRegion((HeapWord*)heap_rs.base(), heap_rs.size() / HeapWordSize); 194 _heap_region_special = heap_rs.special(); 195 196 assert((((size_t) base()) & ShenandoahHeapRegion::region_size_bytes_mask()) == 0, 197 "Misaligned heap: " PTR_FORMAT, p2i(base())); 198 199 #if SHENANDOAH_OPTIMIZED_OBJTASK 200 // The optimized ObjArrayChunkedTask takes some bits away from the full object bits. 201 // Fail if we ever attempt to address more than we can. 202 if ((uintptr_t)heap_rs.end() >= ObjArrayChunkedTask::max_addressable()) { 203 FormatBuffer<512> buf("Shenandoah reserved [" PTR_FORMAT ", " PTR_FORMAT") for the heap, \n" 204 "but max object address is " PTR_FORMAT ". Try to reduce heap size, or try other \n" 205 "VM options that allocate heap at lower addresses (HeapBaseMinAddress, AllocateHeapAt, etc).", 206 p2i(heap_rs.base()), p2i(heap_rs.end()), ObjArrayChunkedTask::max_addressable()); 207 vm_exit_during_initialization("Fatal Error", buf); 208 } 209 #endif 210 211 ReservedSpace sh_rs = heap_rs.first_part(max_byte_size); 212 if (!_heap_region_special) { 213 os::commit_memory_or_exit(sh_rs.base(), _initial_size, heap_alignment, false, 214 "Cannot commit heap memory"); 215 } 216 217 // 218 // Reserve and commit memory for bitmap(s) 219 // 220 221 _bitmap_size = MarkBitMap::compute_size(heap_rs.size()); 222 _bitmap_size = align_up(_bitmap_size, bitmap_page_size); 223 224 size_t bitmap_bytes_per_region = reg_size_bytes / MarkBitMap::heap_map_factor(); 225 226 guarantee(bitmap_bytes_per_region != 0, 227 "Bitmap bytes per region should not be zero"); 228 guarantee(is_power_of_2(bitmap_bytes_per_region), 229 "Bitmap bytes per region should be power of two: " SIZE_FORMAT, bitmap_bytes_per_region); 230 231 if (bitmap_page_size > bitmap_bytes_per_region) { 232 _bitmap_regions_per_slice = bitmap_page_size / bitmap_bytes_per_region; 233 _bitmap_bytes_per_slice = bitmap_page_size; 234 } else { 235 _bitmap_regions_per_slice = 1; 236 _bitmap_bytes_per_slice = bitmap_bytes_per_region; 237 } 238 239 guarantee(_bitmap_regions_per_slice >= 1, 240 "Should have at least one region per slice: " SIZE_FORMAT, 241 _bitmap_regions_per_slice); 242 243 guarantee(((_bitmap_bytes_per_slice) % bitmap_page_size) == 0, 244 "Bitmap slices should be page-granular: bps = " SIZE_FORMAT ", page size = " SIZE_FORMAT, 245 _bitmap_bytes_per_slice, bitmap_page_size); 246 247 ReservedSpace bitmap(_bitmap_size, bitmap_page_size); 248 MemTracker::record_virtual_memory_type(bitmap.base(), mtGC); 249 _bitmap_region = MemRegion((HeapWord*) bitmap.base(), bitmap.size() / HeapWordSize); 250 _bitmap_region_special = bitmap.special(); 251 252 size_t bitmap_init_commit = _bitmap_bytes_per_slice * 253 align_up(num_committed_regions, _bitmap_regions_per_slice) / _bitmap_regions_per_slice; 254 bitmap_init_commit = MIN2(_bitmap_size, bitmap_init_commit); 255 if (!_bitmap_region_special) { 256 os::commit_memory_or_exit((char *) _bitmap_region.start(), bitmap_init_commit, bitmap_page_size, false, 257 "Cannot commit bitmap memory"); 258 } 259 260 _marking_context = new ShenandoahMarkingContext(_heap_region, _bitmap_region, _num_regions); 261 262 if (ShenandoahVerify) { 263 ReservedSpace verify_bitmap(_bitmap_size, bitmap_page_size); 264 if (!verify_bitmap.special()) { 265 os::commit_memory_or_exit(verify_bitmap.base(), verify_bitmap.size(), bitmap_page_size, false, 266 "Cannot commit verification bitmap memory"); 267 } 268 MemTracker::record_virtual_memory_type(verify_bitmap.base(), mtGC); 269 MemRegion verify_bitmap_region = MemRegion((HeapWord *) verify_bitmap.base(), verify_bitmap.size() / HeapWordSize); 270 _verification_bit_map.initialize(_heap_region, verify_bitmap_region); 271 _verifier = new ShenandoahVerifier(this, &_verification_bit_map); 272 } 273 274 // Reserve aux bitmap for use in object_iterate(). We don't commit it here. 275 ReservedSpace aux_bitmap(_bitmap_size, bitmap_page_size); 276 MemTracker::record_virtual_memory_type(aux_bitmap.base(), mtGC); 277 _aux_bitmap_region = MemRegion((HeapWord*) aux_bitmap.base(), aux_bitmap.size() / HeapWordSize); 278 _aux_bitmap_region_special = aux_bitmap.special(); 279 _aux_bit_map.initialize(_heap_region, _aux_bitmap_region); 280 281 // 282 // Create regions and region sets 283 // 284 size_t region_align = align_up(sizeof(ShenandoahHeapRegion), SHENANDOAH_CACHE_LINE_SIZE); 285 size_t region_storage_size = align_up(region_align * _num_regions, region_page_size); 286 region_storage_size = align_up(region_storage_size, os::vm_allocation_granularity()); 287 288 ReservedSpace region_storage(region_storage_size, region_page_size); 289 MemTracker::record_virtual_memory_type(region_storage.base(), mtGC); 290 if (!region_storage.special()) { 291 os::commit_memory_or_exit(region_storage.base(), region_storage_size, region_page_size, false, 292 "Cannot commit region memory"); 293 } 294 295 // Try to fit the collection set bitmap at lower addresses. This optimizes code generation for cset checks. 296 // Go up until a sensible limit (subject to encoding constraints) and try to reserve the space there. 297 // If not successful, bite a bullet and allocate at whatever address. 298 { 299 size_t cset_align = MAX2<size_t>(os::vm_page_size(), os::vm_allocation_granularity()); 300 size_t cset_size = align_up(((size_t) sh_rs.base() + sh_rs.size()) >> ShenandoahHeapRegion::region_size_bytes_shift(), cset_align); 301 302 uintptr_t min = round_up_power_of_2(cset_align); 303 uintptr_t max = (1u << 30u); 304 305 for (uintptr_t addr = min; addr <= max; addr <<= 1u) { 306 char* req_addr = (char*)addr; 307 assert(is_aligned(req_addr, cset_align), "Should be aligned"); 308 ReservedSpace cset_rs(cset_size, cset_align, false, req_addr); 309 if (cset_rs.is_reserved()) { 310 assert(cset_rs.base() == req_addr, "Allocated where requested: " PTR_FORMAT ", " PTR_FORMAT, p2i(cset_rs.base()), addr); 311 _collection_set = new ShenandoahCollectionSet(this, cset_rs, sh_rs.base()); 312 break; 313 } 314 } 315 316 if (_collection_set == NULL) { 317 ReservedSpace cset_rs(cset_size, cset_align, false); 318 _collection_set = new ShenandoahCollectionSet(this, cset_rs, sh_rs.base()); 319 } 320 } 321 322 _regions = NEW_C_HEAP_ARRAY(ShenandoahHeapRegion*, _num_regions, mtGC); 323 _free_set = new ShenandoahFreeSet(this, _num_regions); 324 325 { 326 ShenandoahHeapLocker locker(lock()); 327 328 for (size_t i = 0; i < _num_regions; i++) { 329 HeapWord* start = (HeapWord*)sh_rs.base() + ShenandoahHeapRegion::region_size_words() * i; 330 bool is_committed = i < num_committed_regions; 331 void* loc = region_storage.base() + i * region_align; 332 333 ShenandoahHeapRegion* r = new (loc) ShenandoahHeapRegion(start, i, is_committed); 334 assert(is_aligned(r, SHENANDOAH_CACHE_LINE_SIZE), "Sanity"); 335 336 _marking_context->initialize_top_at_mark_start(r); 337 _regions[i] = r; 338 assert(!collection_set()->is_in(i), "New region should not be in collection set"); 339 } 340 341 // Initialize to complete 342 _marking_context->mark_complete(); 343 344 _free_set->rebuild(); 345 } 346 347 if (AlwaysPreTouch) { 348 // For NUMA, it is important to pre-touch the storage under bitmaps with worker threads, 349 // before initialize() below zeroes it with initializing thread. For any given region, 350 // we touch the region and the corresponding bitmaps from the same thread. 351 ShenandoahPushWorkerScope scope(workers(), _max_workers, false); 352 353 _pretouch_heap_page_size = heap_page_size; 354 _pretouch_bitmap_page_size = bitmap_page_size; 355 356 #ifdef LINUX 357 // UseTransparentHugePages would madvise that backing memory can be coalesced into huge 358 // pages. But, the kernel needs to know that every small page is used, in order to coalesce 359 // them into huge one. Therefore, we need to pretouch with smaller pages. 360 if (UseTransparentHugePages) { 361 _pretouch_heap_page_size = (size_t)os::vm_page_size(); 362 _pretouch_bitmap_page_size = (size_t)os::vm_page_size(); 363 } 364 #endif 365 366 // OS memory managers may want to coalesce back-to-back pages. Make their jobs 367 // simpler by pre-touching continuous spaces (heap and bitmap) separately. 368 369 ShenandoahPretouchBitmapTask bcl(bitmap.base(), _bitmap_size, _pretouch_bitmap_page_size); 370 _workers->run_task(&bcl); 371 372 ShenandoahPretouchHeapTask hcl(_pretouch_heap_page_size); 373 _workers->run_task(&hcl); 374 } 375 376 // 377 // Initialize the rest of GC subsystems 378 // 379 380 _liveness_cache = NEW_C_HEAP_ARRAY(ShenandoahLiveData*, _max_workers, mtGC); 381 for (uint worker = 0; worker < _max_workers; worker++) { 382 _liveness_cache[worker] = NEW_C_HEAP_ARRAY(ShenandoahLiveData, _num_regions, mtGC); 383 Copy::fill_to_bytes(_liveness_cache[worker], _num_regions * sizeof(ShenandoahLiveData)); 384 } 385 386 // There should probably be Shenandoah-specific options for these, 387 // just as there are G1-specific options. 388 { 389 ShenandoahSATBMarkQueueSet& satbqs = ShenandoahBarrierSet::satb_mark_queue_set(); 390 satbqs.set_process_completed_buffers_threshold(20); // G1SATBProcessCompletedThreshold 391 satbqs.set_buffer_enqueue_threshold_percentage(60); // G1SATBBufferEnqueueingThresholdPercent 392 } 393 394 _monitoring_support = new ShenandoahMonitoringSupport(this); 395 _phase_timings = new ShenandoahPhaseTimings(max_workers()); 396 ShenandoahStringDedup::initialize(); 397 ShenandoahCodeRoots::initialize(); 398 399 if (ShenandoahPacing) { 400 _pacer = new ShenandoahPacer(this); 401 _pacer->setup_for_idle(); 402 } else { 403 _pacer = NULL; 404 } 405 406 _control_thread = new ShenandoahControlThread(); 407 408 _ref_proc_mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1); 409 _ref_proc_mt_discovery = _max_workers > 1; 410 411 ShenandoahInitLogger::print(); 412 413 return JNI_OK; 414 } 415 416 void ShenandoahHeap::initialize_heuristics() { 417 if (ShenandoahGCMode != NULL) { 418 if (strcmp(ShenandoahGCMode, "satb") == 0) { 419 _gc_mode = new ShenandoahSATBMode(); 420 } else if (strcmp(ShenandoahGCMode, "iu") == 0) { 421 _gc_mode = new ShenandoahIUMode(); 422 } else if (strcmp(ShenandoahGCMode, "passive") == 0) { 423 _gc_mode = new ShenandoahPassiveMode(); 424 } else { 425 vm_exit_during_initialization("Unknown -XX:ShenandoahGCMode option"); 426 } 427 } else { 428 ShouldNotReachHere(); 429 } 430 _gc_mode->initialize_flags(); 431 if (_gc_mode->is_diagnostic() && !UnlockDiagnosticVMOptions) { 432 vm_exit_during_initialization( 433 err_msg("GC mode \"%s\" is diagnostic, and must be enabled via -XX:+UnlockDiagnosticVMOptions.", 434 _gc_mode->name())); 435 } 436 if (_gc_mode->is_experimental() && !UnlockExperimentalVMOptions) { 437 vm_exit_during_initialization( 438 err_msg("GC mode \"%s\" is experimental, and must be enabled via -XX:+UnlockExperimentalVMOptions.", 439 _gc_mode->name())); 440 } 441 442 _heuristics = _gc_mode->initialize_heuristics(); 443 444 if (_heuristics->is_diagnostic() && !UnlockDiagnosticVMOptions) { 445 vm_exit_during_initialization( 446 err_msg("Heuristics \"%s\" is diagnostic, and must be enabled via -XX:+UnlockDiagnosticVMOptions.", 447 _heuristics->name())); 448 } 449 if (_heuristics->is_experimental() && !UnlockExperimentalVMOptions) { 450 vm_exit_during_initialization( 451 err_msg("Heuristics \"%s\" is experimental, and must be enabled via -XX:+UnlockExperimentalVMOptions.", 452 _heuristics->name())); 453 } 454 } 455 456 #ifdef _MSC_VER 457 #pragma warning( push ) 458 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list 459 #endif 460 461 ShenandoahHeap::ShenandoahHeap(ShenandoahCollectorPolicy* policy) : 462 CollectedHeap(), 463 _initial_size(0), 464 _used(0), 465 _committed(0), 466 _bytes_allocated_since_gc_start(0), 467 _max_workers(MAX2(ConcGCThreads, ParallelGCThreads)), 468 _workers(NULL), 469 _safepoint_workers(NULL), 470 _heap_region_special(false), 471 _num_regions(0), 472 _regions(NULL), 473 _update_refs_iterator(this), 474 _control_thread(NULL), 475 _shenandoah_policy(policy), 476 _heuristics(NULL), 477 _free_set(NULL), 478 _scm(new ShenandoahConcurrentMark()), 479 _full_gc(new ShenandoahMarkCompact()), 480 _pacer(NULL), 481 _verifier(NULL), 482 _phase_timings(NULL), 483 _monitoring_support(NULL), 484 _memory_pool(NULL), 485 _stw_memory_manager("Shenandoah Pauses", "end of GC pause"), 486 _cycle_memory_manager("Shenandoah Cycles", "end of GC cycle"), 487 _gc_timer(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()), 488 _soft_ref_policy(), 489 _log_min_obj_alignment_in_bytes(LogMinObjAlignmentInBytes), 490 _ref_processor(NULL), 491 _marking_context(NULL), 492 _bitmap_size(0), 493 _bitmap_regions_per_slice(0), 494 _bitmap_bytes_per_slice(0), 495 _bitmap_region_special(false), 496 _aux_bitmap_region_special(false), 497 _liveness_cache(NULL), 498 _collection_set(NULL) 499 { 500 _heap = this; 501 502 BarrierSet::set_barrier_set(new ShenandoahBarrierSet(this)); 503 504 _max_workers = MAX2(_max_workers, 1U); 505 _workers = new ShenandoahWorkGang("Shenandoah GC Threads", _max_workers, 506 /* are_GC_task_threads */ true, 507 /* are_ConcurrentGC_threads */ true); 508 if (_workers == NULL) { 509 vm_exit_during_initialization("Failed necessary allocation."); 510 } else { 511 _workers->initialize_workers(); 512 } 513 514 if (ParallelGCThreads > 1) { 515 _safepoint_workers = new ShenandoahWorkGang("Safepoint Cleanup Thread", 516 ParallelGCThreads, 517 /* are_GC_task_threads */ false, 518 /* are_ConcurrentGC_threads */ false); 519 _safepoint_workers->initialize_workers(); 520 } 521 } 522 523 #ifdef _MSC_VER 524 #pragma warning( pop ) 525 #endif 526 527 class ShenandoahResetBitmapTask : public AbstractGangTask { 528 private: 529 ShenandoahRegionIterator _regions; 530 531 public: 532 ShenandoahResetBitmapTask() : 533 AbstractGangTask("Parallel Reset Bitmap Task") {} 534 535 void work(uint worker_id) { 536 ShenandoahHeapRegion* region = _regions.next(); 537 ShenandoahHeap* heap = ShenandoahHeap::heap(); 538 ShenandoahMarkingContext* const ctx = heap->marking_context(); 539 while (region != NULL) { 540 if (heap->is_bitmap_slice_committed(region)) { 541 ctx->clear_bitmap(region); 542 } 543 region = _regions.next(); 544 } 545 } 546 }; 547 548 void ShenandoahHeap::reset_mark_bitmap() { 549 assert_gc_workers(_workers->active_workers()); 550 mark_incomplete_marking_context(); 551 552 ShenandoahResetBitmapTask task; 553 _workers->run_task(&task); 554 } 555 556 void ShenandoahHeap::print_on(outputStream* st) const { 557 st->print_cr("Shenandoah Heap"); 558 st->print_cr(" " SIZE_FORMAT "%s total, " SIZE_FORMAT "%s committed, " SIZE_FORMAT "%s used", 559 byte_size_in_proper_unit(max_capacity()), proper_unit_for_byte_size(max_capacity()), 560 byte_size_in_proper_unit(committed()), proper_unit_for_byte_size(committed()), 561 byte_size_in_proper_unit(used()), proper_unit_for_byte_size(used())); 562 st->print_cr(" " SIZE_FORMAT " x " SIZE_FORMAT"%s regions", 563 num_regions(), 564 byte_size_in_proper_unit(ShenandoahHeapRegion::region_size_bytes()), 565 proper_unit_for_byte_size(ShenandoahHeapRegion::region_size_bytes())); 566 567 st->print("Status: "); 568 if (has_forwarded_objects()) st->print("has forwarded objects, "); 569 if (is_concurrent_mark_in_progress()) st->print("marking, "); 570 if (is_evacuation_in_progress()) st->print("evacuating, "); 571 if (is_update_refs_in_progress()) st->print("updating refs, "); 572 if (is_degenerated_gc_in_progress()) st->print("degenerated gc, "); 573 if (is_full_gc_in_progress()) st->print("full gc, "); 574 if (is_full_gc_move_in_progress()) st->print("full gc move, "); 575 if (is_concurrent_weak_root_in_progress()) st->print("concurrent weak roots, "); 576 if (is_concurrent_strong_root_in_progress() && 577 !is_concurrent_weak_root_in_progress()) st->print("concurrent strong roots, "); 578 579 if (cancelled_gc()) { 580 st->print("cancelled"); 581 } else { 582 st->print("not cancelled"); 583 } 584 st->cr(); 585 586 st->print_cr("Reserved region:"); 587 st->print_cr(" - [" PTR_FORMAT ", " PTR_FORMAT ") ", 588 p2i(reserved_region().start()), 589 p2i(reserved_region().end())); 590 591 ShenandoahCollectionSet* cset = collection_set(); 592 st->print_cr("Collection set:"); 593 if (cset != NULL) { 594 st->print_cr(" - map (vanilla): " PTR_FORMAT, p2i(cset->map_address())); 595 st->print_cr(" - map (biased): " PTR_FORMAT, p2i(cset->biased_map_address())); 596 } else { 597 st->print_cr(" (NULL)"); 598 } 599 600 st->cr(); 601 MetaspaceUtils::print_on(st); 602 603 if (Verbose) { 604 print_heap_regions_on(st); 605 } 606 } 607 608 class ShenandoahInitWorkerGCLABClosure : public ThreadClosure { 609 public: 610 void do_thread(Thread* thread) { 611 assert(thread != NULL, "Sanity"); 612 assert(thread->is_Worker_thread(), "Only worker thread expected"); 613 ShenandoahThreadLocalData::initialize_gclab(thread); 614 } 615 }; 616 617 void ShenandoahHeap::post_initialize() { 618 CollectedHeap::post_initialize(); 619 MutexLocker ml(Threads_lock); 620 621 ShenandoahInitWorkerGCLABClosure init_gclabs; 622 _workers->threads_do(&init_gclabs); 623 624 // gclab can not be initialized early during VM startup, as it can not determinate its max_size. 625 // Now, we will let WorkGang to initialize gclab when new worker is created. 626 _workers->set_initialize_gclab(); 627 628 _scm->initialize(_max_workers); 629 _full_gc->initialize(_gc_timer); 630 631 ref_processing_init(); 632 633 _heuristics->initialize(); 634 635 JFR_ONLY(ShenandoahJFRSupport::register_jfr_type_serializers()); 636 } 637 638 size_t ShenandoahHeap::used() const { 639 return Atomic::load_acquire(&_used); 640 } 641 642 size_t ShenandoahHeap::committed() const { 643 OrderAccess::acquire(); 644 return _committed; 645 } 646 647 void ShenandoahHeap::increase_committed(size_t bytes) { 648 shenandoah_assert_heaplocked_or_safepoint(); 649 _committed += bytes; 650 } 651 652 void ShenandoahHeap::decrease_committed(size_t bytes) { 653 shenandoah_assert_heaplocked_or_safepoint(); 654 _committed -= bytes; 655 } 656 657 void ShenandoahHeap::increase_used(size_t bytes) { 658 Atomic::add(&_used, bytes); 659 } 660 661 void ShenandoahHeap::set_used(size_t bytes) { 662 Atomic::release_store_fence(&_used, bytes); 663 } 664 665 void ShenandoahHeap::decrease_used(size_t bytes) { 666 assert(used() >= bytes, "never decrease heap size by more than we've left"); 667 Atomic::sub(&_used, bytes); 668 } 669 670 void ShenandoahHeap::increase_allocated(size_t bytes) { 671 Atomic::add(&_bytes_allocated_since_gc_start, bytes); 672 } 673 674 void ShenandoahHeap::notify_mutator_alloc_words(size_t words, bool waste) { 675 size_t bytes = words * HeapWordSize; 676 if (!waste) { 677 increase_used(bytes); 678 } 679 increase_allocated(bytes); 680 if (ShenandoahPacing) { 681 control_thread()->pacing_notify_alloc(words); 682 if (waste) { 683 pacer()->claim_for_alloc(words, true); 684 } 685 } 686 } 687 688 size_t ShenandoahHeap::capacity() const { 689 return committed(); 690 } 691 692 size_t ShenandoahHeap::max_capacity() const { 693 return _num_regions * ShenandoahHeapRegion::region_size_bytes(); 694 } 695 696 size_t ShenandoahHeap::min_capacity() const { 697 return _minimum_size; 698 } 699 700 size_t ShenandoahHeap::initial_capacity() const { 701 return _initial_size; 702 } 703 704 bool ShenandoahHeap::is_in(const void* p) const { 705 HeapWord* heap_base = (HeapWord*) base(); 706 HeapWord* last_region_end = heap_base + ShenandoahHeapRegion::region_size_words() * num_regions(); 707 return p >= heap_base && p < last_region_end; 708 } 709 710 void ShenandoahHeap::op_uncommit(double shrink_before) { 711 assert (ShenandoahUncommit, "should be enabled"); 712 713 // Application allocates from the beginning of the heap, and GC allocates at 714 // the end of it. It is more efficient to uncommit from the end, so that applications 715 // could enjoy the near committed regions. GC allocations are much less frequent, 716 // and therefore can accept the committing costs. 717 718 size_t count = 0; 719 for (size_t i = num_regions(); i > 0; i--) { // care about size_t underflow 720 ShenandoahHeapRegion* r = get_region(i - 1); 721 if (r->is_empty_committed() && (r->empty_time() < shrink_before)) { 722 ShenandoahHeapLocker locker(lock()); 723 if (r->is_empty_committed()) { 724 // Do not uncommit below minimal capacity 725 if (committed() < min_capacity() + ShenandoahHeapRegion::region_size_bytes()) { 726 break; 727 } 728 729 r->make_uncommitted(); 730 count++; 731 } 732 } 733 SpinPause(); // allow allocators to take the lock 734 } 735 736 if (count > 0) { 737 control_thread()->notify_heap_changed(); 738 } 739 } 740 741 HeapWord* ShenandoahHeap::allocate_from_gclab_slow(Thread* thread, size_t size) { 742 // New object should fit the GCLAB size 743 size_t min_size = MAX2(size, PLAB::min_size()); 744 745 // Figure out size of new GCLAB, looking back at heuristics. Expand aggressively. 746 size_t new_size = ShenandoahThreadLocalData::gclab_size(thread) * 2; 747 new_size = MIN2(new_size, PLAB::max_size()); 748 new_size = MAX2(new_size, PLAB::min_size()); 749 750 // Record new heuristic value even if we take any shortcut. This captures 751 // the case when moderately-sized objects always take a shortcut. At some point, 752 // heuristics should catch up with them. 753 ShenandoahThreadLocalData::set_gclab_size(thread, new_size); 754 755 if (new_size < size) { 756 // New size still does not fit the object. Fall back to shared allocation. 757 // This avoids retiring perfectly good GCLABs, when we encounter a large object. 758 return NULL; 759 } 760 761 // Retire current GCLAB, and allocate a new one. 762 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread); 763 gclab->retire(); 764 765 size_t actual_size = 0; 766 HeapWord* gclab_buf = allocate_new_gclab(min_size, new_size, &actual_size); 767 if (gclab_buf == NULL) { 768 return NULL; 769 } 770 771 assert (size <= actual_size, "allocation should fit"); 772 773 if (ZeroTLAB) { 774 // ..and clear it. 775 Copy::zero_to_words(gclab_buf, actual_size); 776 } else { 777 // ...and zap just allocated object. 778 #ifdef ASSERT 779 // Skip mangling the space corresponding to the object header to 780 // ensure that the returned space is not considered parsable by 781 // any concurrent GC thread. 782 size_t hdr_size = oopDesc::header_size(); 783 Copy::fill_to_words(gclab_buf + hdr_size, actual_size - hdr_size, badHeapWordVal); 784 #endif // ASSERT 785 } 786 gclab->set_buf(gclab_buf, actual_size); 787 return gclab->allocate(size); 788 } 789 790 HeapWord* ShenandoahHeap::allocate_new_tlab(size_t min_size, 791 size_t requested_size, 792 size_t* actual_size) { 793 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_tlab(min_size, requested_size); 794 HeapWord* res = allocate_memory(req); 795 if (res != NULL) { 796 *actual_size = req.actual_size(); 797 } else { 798 *actual_size = 0; 799 } 800 return res; 801 } 802 803 HeapWord* ShenandoahHeap::allocate_new_gclab(size_t min_size, 804 size_t word_size, 805 size_t* actual_size) { 806 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_gclab(min_size, word_size); 807 HeapWord* res = allocate_memory(req); 808 if (res != NULL) { 809 *actual_size = req.actual_size(); 810 } else { 811 *actual_size = 0; 812 } 813 return res; 814 } 815 816 HeapWord* ShenandoahHeap::allocate_memory(ShenandoahAllocRequest& req) { 817 intptr_t pacer_epoch = 0; 818 bool in_new_region = false; 819 HeapWord* result = NULL; 820 821 if (req.is_mutator_alloc()) { 822 if (ShenandoahPacing) { 823 pacer()->pace_for_alloc(req.size()); 824 pacer_epoch = pacer()->epoch(); 825 } 826 827 if (!ShenandoahAllocFailureALot || !should_inject_alloc_failure()) { 828 result = allocate_memory_under_lock(req, in_new_region); 829 } 830 831 // Allocation failed, block until control thread reacted, then retry allocation. 832 // 833 // It might happen that one of the threads requesting allocation would unblock 834 // way later after GC happened, only to fail the second allocation, because 835 // other threads have already depleted the free storage. In this case, a better 836 // strategy is to try again, as long as GC makes progress. 837 // 838 // Then, we need to make sure the allocation was retried after at least one 839 // Full GC, which means we want to try more than ShenandoahFullGCThreshold times. 840 841 size_t tries = 0; 842 843 while (result == NULL && _progress_last_gc.is_set()) { 844 tries++; 845 control_thread()->handle_alloc_failure(req); 846 result = allocate_memory_under_lock(req, in_new_region); 847 } 848 849 while (result == NULL && tries <= ShenandoahFullGCThreshold) { 850 tries++; 851 control_thread()->handle_alloc_failure(req); 852 result = allocate_memory_under_lock(req, in_new_region); 853 } 854 855 } else { 856 assert(req.is_gc_alloc(), "Can only accept GC allocs here"); 857 result = allocate_memory_under_lock(req, in_new_region); 858 // Do not call handle_alloc_failure() here, because we cannot block. 859 // The allocation failure would be handled by the LRB slowpath with handle_alloc_failure_evac(). 860 } 861 862 if (in_new_region) { 863 control_thread()->notify_heap_changed(); 864 } 865 866 if (result != NULL) { 867 size_t requested = req.size(); 868 size_t actual = req.actual_size(); 869 870 assert (req.is_lab_alloc() || (requested == actual), 871 "Only LAB allocations are elastic: %s, requested = " SIZE_FORMAT ", actual = " SIZE_FORMAT, 872 ShenandoahAllocRequest::alloc_type_to_string(req.type()), requested, actual); 873 874 if (req.is_mutator_alloc()) { 875 notify_mutator_alloc_words(actual, false); 876 877 // If we requested more than we were granted, give the rest back to pacer. 878 // This only matters if we are in the same pacing epoch: do not try to unpace 879 // over the budget for the other phase. 880 if (ShenandoahPacing && (pacer_epoch > 0) && (requested > actual)) { 881 pacer()->unpace_for_alloc(pacer_epoch, requested - actual); 882 } 883 } else { 884 increase_used(actual*HeapWordSize); 885 } 886 } 887 888 return result; 889 } 890 891 HeapWord* ShenandoahHeap::allocate_memory_under_lock(ShenandoahAllocRequest& req, bool& in_new_region) { 892 ShenandoahHeapLocker locker(lock()); 893 return _free_set->allocate(req, in_new_region); 894 } 895 896 HeapWord* ShenandoahHeap::mem_allocate(size_t size, 897 bool* gc_overhead_limit_was_exceeded) { 898 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_shared(size); 899 return allocate_memory(req); 900 } 901 902 MetaWord* ShenandoahHeap::satisfy_failed_metadata_allocation(ClassLoaderData* loader_data, 903 size_t size, 904 Metaspace::MetadataType mdtype) { 905 MetaWord* result; 906 907 // Inform metaspace OOM to GC heuristics if class unloading is possible. 908 if (heuristics()->can_unload_classes()) { 909 ShenandoahHeuristics* h = heuristics(); 910 h->record_metaspace_oom(); 911 } 912 913 // Expand and retry allocation 914 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype); 915 if (result != NULL) { 916 return result; 917 } 918 919 // Start full GC 920 collect(GCCause::_metadata_GC_clear_soft_refs); 921 922 // Retry allocation 923 result = loader_data->metaspace_non_null()->allocate(size, mdtype); 924 if (result != NULL) { 925 return result; 926 } 927 928 // Expand and retry allocation 929 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype); 930 if (result != NULL) { 931 return result; 932 } 933 934 // Out of memory 935 return NULL; 936 } 937 938 class ShenandoahConcurrentEvacuateRegionObjectClosure : public ObjectClosure { 939 private: 940 ShenandoahHeap* const _heap; 941 Thread* const _thread; 942 public: 943 ShenandoahConcurrentEvacuateRegionObjectClosure(ShenandoahHeap* heap) : 944 _heap(heap), _thread(Thread::current()) {} 945 946 void do_object(oop p) { 947 shenandoah_assert_marked(NULL, p); 948 if (!p->is_forwarded()) { 949 _heap->evacuate_object(p, _thread); 950 } 951 } 952 }; 953 954 class ShenandoahEvacuationTask : public AbstractGangTask { 955 private: 956 ShenandoahHeap* const _sh; 957 ShenandoahCollectionSet* const _cs; 958 bool _concurrent; 959 public: 960 ShenandoahEvacuationTask(ShenandoahHeap* sh, 961 ShenandoahCollectionSet* cs, 962 bool concurrent) : 963 AbstractGangTask("Parallel Evacuation Task"), 964 _sh(sh), 965 _cs(cs), 966 _concurrent(concurrent) 967 {} 968 969 void work(uint worker_id) { 970 if (_concurrent) { 971 ShenandoahConcurrentWorkerSession worker_session(worker_id); 972 ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers); 973 ShenandoahEvacOOMScope oom_evac_scope; 974 do_work(); 975 } else { 976 ShenandoahParallelWorkerSession worker_session(worker_id); 977 ShenandoahEvacOOMScope oom_evac_scope; 978 do_work(); 979 } 980 } 981 982 private: 983 void do_work() { 984 ShenandoahConcurrentEvacuateRegionObjectClosure cl(_sh); 985 ShenandoahHeapRegion* r; 986 while ((r =_cs->claim_next()) != NULL) { 987 assert(r->has_live(), "Region " SIZE_FORMAT " should have been reclaimed early", r->index()); 988 _sh->marked_object_iterate(r, &cl); 989 990 if (ShenandoahPacing) { 991 _sh->pacer()->report_evac(r->used() >> LogHeapWordSize); 992 } 993 994 if (_sh->check_cancelled_gc_and_yield(_concurrent)) { 995 break; 996 } 997 } 998 } 999 }; 1000 1001 void ShenandoahHeap::trash_cset_regions() { 1002 ShenandoahHeapLocker locker(lock()); 1003 1004 ShenandoahCollectionSet* set = collection_set(); 1005 ShenandoahHeapRegion* r; 1006 set->clear_current_index(); 1007 while ((r = set->next()) != NULL) { 1008 r->make_trash(); 1009 } 1010 collection_set()->clear(); 1011 } 1012 1013 void ShenandoahHeap::print_heap_regions_on(outputStream* st) const { 1014 st->print_cr("Heap Regions:"); 1015 st->print_cr("EU=empty-uncommitted, EC=empty-committed, R=regular, H=humongous start, HC=humongous continuation, CS=collection set, T=trash, P=pinned"); 1016 st->print_cr("BTE=bottom/top/end, U=used, T=TLAB allocs, G=GCLAB allocs, S=shared allocs, L=live data"); 1017 st->print_cr("R=root, CP=critical pins, TAMS=top-at-mark-start, UWM=update watermark"); 1018 st->print_cr("SN=alloc sequence number"); 1019 1020 for (size_t i = 0; i < num_regions(); i++) { 1021 get_region(i)->print_on(st); 1022 } 1023 } 1024 1025 void ShenandoahHeap::trash_humongous_region_at(ShenandoahHeapRegion* start) { 1026 assert(start->is_humongous_start(), "reclaim regions starting with the first one"); 1027 1028 oop humongous_obj = oop(start->bottom()); 1029 size_t size = humongous_obj->size(); 1030 size_t required_regions = ShenandoahHeapRegion::required_regions(size * HeapWordSize); 1031 size_t index = start->index() + required_regions - 1; 1032 1033 assert(!start->has_live(), "liveness must be zero"); 1034 1035 for(size_t i = 0; i < required_regions; i++) { 1036 // Reclaim from tail. Otherwise, assertion fails when printing region to trace log, 1037 // as it expects that every region belongs to a humongous region starting with a humongous start region. 1038 ShenandoahHeapRegion* region = get_region(index --); 1039 1040 assert(region->is_humongous(), "expect correct humongous start or continuation"); 1041 assert(!region->is_cset(), "Humongous region should not be in collection set"); 1042 1043 region->make_trash_immediate(); 1044 } 1045 } 1046 1047 class ShenandoahRetireGCLABClosure : public ThreadClosure { 1048 public: 1049 void do_thread(Thread* thread) { 1050 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread); 1051 assert(gclab != NULL, "GCLAB should be initialized for %s", thread->name()); 1052 gclab->retire(); 1053 } 1054 }; 1055 1056 void ShenandoahHeap::make_parsable(bool retire_tlabs) { 1057 if (UseTLAB) { 1058 CollectedHeap::ensure_parsability(retire_tlabs); 1059 } 1060 ShenandoahRetireGCLABClosure cl; 1061 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) { 1062 cl.do_thread(t); 1063 } 1064 workers()->threads_do(&cl); 1065 } 1066 1067 void ShenandoahHeap::resize_tlabs() { 1068 CollectedHeap::resize_all_tlabs(); 1069 } 1070 1071 class ShenandoahEvacuateUpdateRootsTask : public AbstractGangTask { 1072 private: 1073 ShenandoahRootEvacuator* _rp; 1074 1075 public: 1076 ShenandoahEvacuateUpdateRootsTask(ShenandoahRootEvacuator* rp) : 1077 AbstractGangTask("Shenandoah evacuate and update roots"), 1078 _rp(rp) {} 1079 1080 void work(uint worker_id) { 1081 ShenandoahParallelWorkerSession worker_session(worker_id); 1082 ShenandoahEvacOOMScope oom_evac_scope; 1083 ShenandoahEvacuateUpdateRootsClosure<> cl; 1084 MarkingCodeBlobClosure blobsCl(&cl, CodeBlobToOopClosure::FixRelocations); 1085 _rp->roots_do(worker_id, &cl); 1086 } 1087 }; 1088 1089 void ShenandoahHeap::evacuate_and_update_roots() { 1090 #if COMPILER2_OR_JVMCI 1091 DerivedPointerTable::clear(); 1092 #endif 1093 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Only iterate roots while world is stopped"); 1094 { 1095 // Include concurrent roots if current cycle can not process those roots concurrently 1096 ShenandoahRootEvacuator rp(workers()->active_workers(), 1097 ShenandoahPhaseTimings::init_evac, 1098 !ShenandoahConcurrentRoots::should_do_concurrent_roots(), 1099 !ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()); 1100 ShenandoahEvacuateUpdateRootsTask roots_task(&rp); 1101 workers()->run_task(&roots_task); 1102 } 1103 1104 #if COMPILER2_OR_JVMCI 1105 DerivedPointerTable::update_pointers(); 1106 #endif 1107 } 1108 1109 // Returns size in bytes 1110 size_t ShenandoahHeap::unsafe_max_tlab_alloc(Thread *thread) const { 1111 if (ShenandoahElasticTLAB) { 1112 // With Elastic TLABs, return the max allowed size, and let the allocation path 1113 // figure out the safe size for current allocation. 1114 return ShenandoahHeapRegion::max_tlab_size_bytes(); 1115 } else { 1116 return MIN2(_free_set->unsafe_peek_free(), ShenandoahHeapRegion::max_tlab_size_bytes()); 1117 } 1118 } 1119 1120 size_t ShenandoahHeap::max_tlab_size() const { 1121 // Returns size in words 1122 return ShenandoahHeapRegion::max_tlab_size_words(); 1123 } 1124 1125 class ShenandoahRetireAndResetGCLABClosure : public ThreadClosure { 1126 public: 1127 void do_thread(Thread* thread) { 1128 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread); 1129 gclab->retire(); 1130 if (ShenandoahThreadLocalData::gclab_size(thread) > 0) { 1131 ShenandoahThreadLocalData::set_gclab_size(thread, 0); 1132 } 1133 } 1134 }; 1135 1136 void ShenandoahHeap::retire_and_reset_gclabs() { 1137 ShenandoahRetireAndResetGCLABClosure cl; 1138 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) { 1139 cl.do_thread(t); 1140 } 1141 workers()->threads_do(&cl); 1142 } 1143 1144 void ShenandoahHeap::collect(GCCause::Cause cause) { 1145 control_thread()->request_gc(cause); 1146 } 1147 1148 void ShenandoahHeap::do_full_collection(bool clear_all_soft_refs) { 1149 //assert(false, "Shouldn't need to do full collections"); 1150 } 1151 1152 HeapWord* ShenandoahHeap::block_start(const void* addr) const { 1153 ShenandoahHeapRegion* r = heap_region_containing(addr); 1154 if (r != NULL) { 1155 return r->block_start(addr); 1156 } 1157 return NULL; 1158 } 1159 1160 bool ShenandoahHeap::block_is_obj(const HeapWord* addr) const { 1161 ShenandoahHeapRegion* r = heap_region_containing(addr); 1162 return r->block_is_obj(addr); 1163 } 1164 1165 bool ShenandoahHeap::print_location(outputStream* st, void* addr) const { 1166 return BlockLocationPrinter<ShenandoahHeap>::print_location(st, addr); 1167 } 1168 1169 jlong ShenandoahHeap::millis_since_last_gc() { 1170 double v = heuristics()->time_since_last_gc() * 1000; 1171 assert(0 <= v && v <= max_jlong, "value should fit: %f", v); 1172 return (jlong)v; 1173 } 1174 1175 void ShenandoahHeap::prepare_for_verify() { 1176 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) { 1177 make_parsable(false); 1178 } 1179 } 1180 1181 void ShenandoahHeap::print_gc_threads_on(outputStream* st) const { 1182 workers()->print_worker_threads_on(st); 1183 if (ShenandoahStringDedup::is_enabled()) { 1184 ShenandoahStringDedup::print_worker_threads_on(st); 1185 } 1186 } 1187 1188 void ShenandoahHeap::gc_threads_do(ThreadClosure* tcl) const { 1189 workers()->threads_do(tcl); 1190 if (_safepoint_workers != NULL) { 1191 _safepoint_workers->threads_do(tcl); 1192 } 1193 if (ShenandoahStringDedup::is_enabled()) { 1194 ShenandoahStringDedup::threads_do(tcl); 1195 } 1196 } 1197 1198 void ShenandoahHeap::print_tracing_info() const { 1199 LogTarget(Info, gc, stats) lt; 1200 if (lt.is_enabled()) { 1201 ResourceMark rm; 1202 LogStream ls(lt); 1203 1204 phase_timings()->print_global_on(&ls); 1205 1206 ls.cr(); 1207 ls.cr(); 1208 1209 shenandoah_policy()->print_gc_stats(&ls); 1210 1211 ls.cr(); 1212 ls.cr(); 1213 1214 if (ShenandoahPacing) { 1215 pacer()->print_on(&ls); 1216 } 1217 1218 ls.cr(); 1219 ls.cr(); 1220 } 1221 } 1222 1223 void ShenandoahHeap::verify(VerifyOption vo) { 1224 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) { 1225 if (ShenandoahVerify) { 1226 verifier()->verify_generic(vo); 1227 } else { 1228 // TODO: Consider allocating verification bitmaps on demand, 1229 // and turn this on unconditionally. 1230 } 1231 } 1232 } 1233 size_t ShenandoahHeap::tlab_capacity(Thread *thr) const { 1234 return _free_set->capacity(); 1235 } 1236 1237 class ObjectIterateScanRootClosure : public BasicOopIterateClosure { 1238 private: 1239 MarkBitMap* _bitmap; 1240 Stack<oop,mtGC>* _oop_stack; 1241 ShenandoahHeap* const _heap; 1242 ShenandoahMarkingContext* const _marking_context; 1243 1244 template <class T> 1245 void do_oop_work(T* p) { 1246 T o = RawAccess<>::oop_load(p); 1247 if (!CompressedOops::is_null(o)) { 1248 oop obj = CompressedOops::decode_not_null(o); 1249 if (_heap->is_concurrent_weak_root_in_progress() && !_marking_context->is_marked(obj)) { 1250 // There may be dead oops in weak roots in concurrent root phase, do not touch them. 1251 return; 1252 } 1253 obj = ShenandoahBarrierSet::resolve_forwarded_not_null(obj); 1254 1255 assert(oopDesc::is_oop(obj), "must be a valid oop"); 1256 if (!_bitmap->is_marked(obj)) { 1257 _bitmap->mark(obj); 1258 _oop_stack->push(obj); 1259 } 1260 } 1261 } 1262 public: 1263 ObjectIterateScanRootClosure(MarkBitMap* bitmap, Stack<oop,mtGC>* oop_stack) : 1264 _bitmap(bitmap), _oop_stack(oop_stack), _heap(ShenandoahHeap::heap()), 1265 _marking_context(_heap->marking_context()) {} 1266 void do_oop(oop* p) { do_oop_work(p); } 1267 void do_oop(narrowOop* p) { do_oop_work(p); } 1268 }; 1269 1270 /* 1271 * This is public API, used in preparation of object_iterate(). 1272 * Since we don't do linear scan of heap in object_iterate() (see comment below), we don't 1273 * need to make the heap parsable. For Shenandoah-internal linear heap scans that we can 1274 * control, we call SH::make_tlabs_parsable(). 1275 */ 1276 void ShenandoahHeap::ensure_parsability(bool retire_tlabs) { 1277 // No-op. 1278 } 1279 1280 /* 1281 * Iterates objects in the heap. This is public API, used for, e.g., heap dumping. 1282 * 1283 * We cannot safely iterate objects by doing a linear scan at random points in time. Linear 1284 * scanning needs to deal with dead objects, which may have dead Klass* pointers (e.g. 1285 * calling oopDesc::size() would crash) or dangling reference fields (crashes) etc. Linear 1286 * scanning therefore depends on having a valid marking bitmap to support it. However, we only 1287 * have a valid marking bitmap after successful marking. In particular, we *don't* have a valid 1288 * marking bitmap during marking, after aborted marking or during/after cleanup (when we just 1289 * wiped the bitmap in preparation for next marking). 1290 * 1291 * For all those reasons, we implement object iteration as a single marking traversal, reporting 1292 * objects as we mark+traverse through the heap, starting from GC roots. JVMTI IterateThroughHeap 1293 * is allowed to report dead objects, but is not required to do so. 1294 */ 1295 void ShenandoahHeap::object_iterate(ObjectClosure* cl) { 1296 assert(SafepointSynchronize::is_at_safepoint(), "safe iteration is only available during safepoints"); 1297 if (!_aux_bitmap_region_special && !os::commit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size(), false)) { 1298 log_warning(gc)("Could not commit native memory for auxiliary marking bitmap for heap iteration"); 1299 return; 1300 } 1301 1302 // Reset bitmap 1303 _aux_bit_map.clear(); 1304 1305 Stack<oop,mtGC> oop_stack; 1306 1307 // First, we process GC roots according to current GC cycle. This populates the work stack with initial objects. 1308 ShenandoahHeapIterationRootScanner rp; 1309 ObjectIterateScanRootClosure oops(&_aux_bit_map, &oop_stack); 1310 1311 rp.roots_do(&oops); 1312 1313 // Work through the oop stack to traverse heap. 1314 while (! oop_stack.is_empty()) { 1315 oop obj = oop_stack.pop(); 1316 assert(oopDesc::is_oop(obj), "must be a valid oop"); 1317 cl->do_object(obj); 1318 obj->oop_iterate(&oops); 1319 } 1320 1321 assert(oop_stack.is_empty(), "should be empty"); 1322 1323 if (!_aux_bitmap_region_special && !os::uncommit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size())) { 1324 log_warning(gc)("Could not uncommit native memory for auxiliary marking bitmap for heap iteration"); 1325 } 1326 } 1327 1328 // Keep alive an object that was loaded with AS_NO_KEEPALIVE. 1329 void ShenandoahHeap::keep_alive(oop obj) { 1330 if (is_concurrent_mark_in_progress()) { 1331 ShenandoahBarrierSet::barrier_set()->enqueue(obj); 1332 } 1333 } 1334 1335 void ShenandoahHeap::heap_region_iterate(ShenandoahHeapRegionClosure* blk) const { 1336 for (size_t i = 0; i < num_regions(); i++) { 1337 ShenandoahHeapRegion* current = get_region(i); 1338 blk->heap_region_do(current); 1339 } 1340 } 1341 1342 class ShenandoahParallelHeapRegionTask : public AbstractGangTask { 1343 private: 1344 ShenandoahHeap* const _heap; 1345 ShenandoahHeapRegionClosure* const _blk; 1346 1347 shenandoah_padding(0); 1348 volatile size_t _index; 1349 shenandoah_padding(1); 1350 1351 public: 1352 ShenandoahParallelHeapRegionTask(ShenandoahHeapRegionClosure* blk) : 1353 AbstractGangTask("Parallel Region Task"), 1354 _heap(ShenandoahHeap::heap()), _blk(blk), _index(0) {} 1355 1356 void work(uint worker_id) { 1357 ShenandoahParallelWorkerSession worker_session(worker_id); 1358 size_t stride = ShenandoahParallelRegionStride; 1359 1360 size_t max = _heap->num_regions(); 1361 while (_index < max) { 1362 size_t cur = Atomic::fetch_and_add(&_index, stride); 1363 size_t start = cur; 1364 size_t end = MIN2(cur + stride, max); 1365 if (start >= max) break; 1366 1367 for (size_t i = cur; i < end; i++) { 1368 ShenandoahHeapRegion* current = _heap->get_region(i); 1369 _blk->heap_region_do(current); 1370 } 1371 } 1372 } 1373 }; 1374 1375 void ShenandoahHeap::parallel_heap_region_iterate(ShenandoahHeapRegionClosure* blk) const { 1376 assert(blk->is_thread_safe(), "Only thread-safe closures here"); 1377 if (num_regions() > ShenandoahParallelRegionStride) { 1378 ShenandoahParallelHeapRegionTask task(blk); 1379 workers()->run_task(&task); 1380 } else { 1381 heap_region_iterate(blk); 1382 } 1383 } 1384 1385 class ShenandoahInitMarkUpdateRegionStateClosure : public ShenandoahHeapRegionClosure { 1386 private: 1387 ShenandoahMarkingContext* const _ctx; 1388 public: 1389 ShenandoahInitMarkUpdateRegionStateClosure() : _ctx(ShenandoahHeap::heap()->marking_context()) {} 1390 1391 void heap_region_do(ShenandoahHeapRegion* r) { 1392 assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->index()); 1393 if (r->is_active()) { 1394 // Check if region needs updating its TAMS. We have updated it already during concurrent 1395 // reset, so it is very likely we don't need to do another write here. 1396 if (_ctx->top_at_mark_start(r) != r->top()) { 1397 _ctx->capture_top_at_mark_start(r); 1398 } 1399 } else { 1400 assert(_ctx->top_at_mark_start(r) == r->top(), 1401 "Region " SIZE_FORMAT " should already have correct TAMS", r->index()); 1402 } 1403 } 1404 1405 bool is_thread_safe() { return true; } 1406 }; 1407 1408 void ShenandoahHeap::op_init_mark() { 1409 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should be at safepoint"); 1410 assert(Thread::current()->is_VM_thread(), "can only do this in VMThread"); 1411 1412 assert(marking_context()->is_bitmap_clear(), "need clear marking bitmap"); 1413 assert(!marking_context()->is_complete(), "should not be complete"); 1414 assert(!has_forwarded_objects(), "No forwarded objects on this path"); 1415 1416 if (ShenandoahVerify) { 1417 verifier()->verify_before_concmark(); 1418 } 1419 1420 if (VerifyBeforeGC) { 1421 Universe::verify(); 1422 } 1423 1424 set_concurrent_mark_in_progress(true); 1425 // We need to reset all TLABs because we'd lose marks on all objects allocated in them. 1426 { 1427 ShenandoahGCPhase phase(ShenandoahPhaseTimings::make_parsable); 1428 make_parsable(true); 1429 } 1430 1431 { 1432 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_region_states); 1433 ShenandoahInitMarkUpdateRegionStateClosure cl; 1434 parallel_heap_region_iterate(&cl); 1435 } 1436 1437 // Make above changes visible to worker threads 1438 OrderAccess::fence(); 1439 1440 concurrent_mark()->mark_roots(ShenandoahPhaseTimings::scan_roots); 1441 1442 if (UseTLAB) { 1443 ShenandoahGCPhase phase(ShenandoahPhaseTimings::resize_tlabs); 1444 resize_tlabs(); 1445 } 1446 1447 if (ShenandoahPacing) { 1448 pacer()->setup_for_mark(); 1449 } 1450 1451 // Arm nmethods for concurrent marking. When a nmethod is about to be executed, 1452 // we need to make sure that all its metadata are marked. alternative is to remark 1453 // thread roots at final mark pause, but it can be potential latency killer. 1454 if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) { 1455 ShenandoahCodeRoots::arm_nmethods(); 1456 } 1457 } 1458 1459 void ShenandoahHeap::op_mark() { 1460 concurrent_mark()->mark_from_roots(); 1461 } 1462 1463 class ShenandoahFinalMarkUpdateRegionStateClosure : public ShenandoahHeapRegionClosure { 1464 private: 1465 ShenandoahMarkingContext* const _ctx; 1466 ShenandoahHeapLock* const _lock; 1467 1468 public: 1469 ShenandoahFinalMarkUpdateRegionStateClosure() : 1470 _ctx(ShenandoahHeap::heap()->complete_marking_context()), _lock(ShenandoahHeap::heap()->lock()) {} 1471 1472 void heap_region_do(ShenandoahHeapRegion* r) { 1473 if (r->is_active()) { 1474 // All allocations past TAMS are implicitly live, adjust the region data. 1475 // Bitmaps/TAMS are swapped at this point, so we need to poll complete bitmap. 1476 HeapWord *tams = _ctx->top_at_mark_start(r); 1477 HeapWord *top = r->top(); 1478 if (top > tams) { 1479 r->increase_live_data_alloc_words(pointer_delta(top, tams)); 1480 } 1481 1482 // We are about to select the collection set, make sure it knows about 1483 // current pinning status. Also, this allows trashing more regions that 1484 // now have their pinning status dropped. 1485 if (r->is_pinned()) { 1486 if (r->pin_count() == 0) { 1487 ShenandoahHeapLocker locker(_lock); 1488 r->make_unpinned(); 1489 } 1490 } else { 1491 if (r->pin_count() > 0) { 1492 ShenandoahHeapLocker locker(_lock); 1493 r->make_pinned(); 1494 } 1495 } 1496 1497 // Remember limit for updating refs. It's guaranteed that we get no 1498 // from-space-refs written from here on. 1499 r->set_update_watermark_at_safepoint(r->top()); 1500 } else { 1501 assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->index()); 1502 assert(_ctx->top_at_mark_start(r) == r->top(), 1503 "Region " SIZE_FORMAT " should have correct TAMS", r->index()); 1504 } 1505 } 1506 1507 bool is_thread_safe() { return true; } 1508 }; 1509 1510 void ShenandoahHeap::op_final_mark() { 1511 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should be at safepoint"); 1512 assert(!has_forwarded_objects(), "No forwarded objects on this path"); 1513 1514 // It is critical that we 1515 // evacuate roots right after finishing marking, so that we don't 1516 // get unmarked objects in the roots. 1517 1518 if (!cancelled_gc()) { 1519 concurrent_mark()->finish_mark_from_roots(/* full_gc = */ false); 1520 1521 // Marking is completed, deactivate SATB barrier 1522 set_concurrent_mark_in_progress(false); 1523 mark_complete_marking_context(); 1524 1525 parallel_cleaning(false /* full gc*/); 1526 1527 if (ShenandoahVerify) { 1528 verifier()->verify_roots_no_forwarded(); 1529 } 1530 1531 { 1532 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_region_states); 1533 ShenandoahFinalMarkUpdateRegionStateClosure cl; 1534 parallel_heap_region_iterate(&cl); 1535 1536 assert_pinned_region_status(); 1537 } 1538 1539 // Retire the TLABs, which will force threads to reacquire their TLABs after the pause. 1540 // This is needed for two reasons. Strong one: new allocations would be with new freeset, 1541 // which would be outside the collection set, so no cset writes would happen there. 1542 // Weaker one: new allocations would happen past update watermark, and so less work would 1543 // be needed for reference updates (would update the large filler instead). 1544 { 1545 ShenandoahGCPhase phase(ShenandoahPhaseTimings::retire_tlabs); 1546 make_parsable(true); 1547 } 1548 1549 { 1550 ShenandoahGCPhase phase(ShenandoahPhaseTimings::choose_cset); 1551 ShenandoahHeapLocker locker(lock()); 1552 _collection_set->clear(); 1553 heuristics()->choose_collection_set(_collection_set); 1554 } 1555 1556 { 1557 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_rebuild_freeset); 1558 ShenandoahHeapLocker locker(lock()); 1559 _free_set->rebuild(); 1560 } 1561 1562 if (!is_degenerated_gc_in_progress()) { 1563 prepare_concurrent_roots(); 1564 prepare_concurrent_unloading(); 1565 } 1566 1567 // If collection set has candidates, start evacuation. 1568 // Otherwise, bypass the rest of the cycle. 1569 if (!collection_set()->is_empty()) { 1570 ShenandoahGCPhase init_evac(ShenandoahPhaseTimings::init_evac); 1571 1572 if (ShenandoahVerify) { 1573 verifier()->verify_before_evacuation(); 1574 } 1575 1576 set_evacuation_in_progress(true); 1577 // From here on, we need to update references. 1578 set_has_forwarded_objects(true); 1579 1580 if (!is_degenerated_gc_in_progress()) { 1581 if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) { 1582 ShenandoahCodeRoots::arm_nmethods(); 1583 } 1584 evacuate_and_update_roots(); 1585 } 1586 1587 if (ShenandoahPacing) { 1588 pacer()->setup_for_evac(); 1589 } 1590 1591 if (ShenandoahVerify) { 1592 ShenandoahRootVerifier::RootTypes types = ShenandoahRootVerifier::None; 1593 if (ShenandoahConcurrentRoots::should_do_concurrent_roots()) { 1594 types = ShenandoahRootVerifier::combine(ShenandoahRootVerifier::JNIHandleRoots, ShenandoahRootVerifier::WeakRoots); 1595 types = ShenandoahRootVerifier::combine(types, ShenandoahRootVerifier::CLDGRoots); 1596 types = ShenandoahRootVerifier::combine(types, ShenandoahRootVerifier::StringDedupRoots); 1597 } 1598 1599 if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) { 1600 types = ShenandoahRootVerifier::combine(types, ShenandoahRootVerifier::CodeRoots); 1601 } 1602 verifier()->verify_roots_no_forwarded_except(types); 1603 verifier()->verify_during_evacuation(); 1604 } 1605 } else { 1606 if (ShenandoahVerify) { 1607 verifier()->verify_after_concmark(); 1608 } 1609 1610 if (VerifyAfterGC) { 1611 Universe::verify(); 1612 } 1613 } 1614 1615 } else { 1616 // If this cycle was updating references, we need to keep the has_forwarded_objects 1617 // flag on, for subsequent phases to deal with it. 1618 concurrent_mark()->cancel(); 1619 set_concurrent_mark_in_progress(false); 1620 1621 if (process_references()) { 1622 // Abandon reference processing right away: pre-cleaning must have failed. 1623 ReferenceProcessor *rp = ref_processor(); 1624 rp->disable_discovery(); 1625 rp->abandon_partial_discovery(); 1626 rp->verify_no_references_recorded(); 1627 } 1628 } 1629 } 1630 1631 void ShenandoahHeap::op_conc_evac() { 1632 ShenandoahEvacuationTask task(this, _collection_set, true); 1633 workers()->run_task(&task); 1634 } 1635 1636 void ShenandoahHeap::op_stw_evac() { 1637 ShenandoahEvacuationTask task(this, _collection_set, false); 1638 workers()->run_task(&task); 1639 } 1640 1641 void ShenandoahHeap::op_updaterefs() { 1642 update_heap_references(true); 1643 } 1644 1645 void ShenandoahHeap::op_cleanup_early() { 1646 free_set()->recycle_trash(); 1647 } 1648 1649 void ShenandoahHeap::op_cleanup_complete() { 1650 free_set()->recycle_trash(); 1651 } 1652 1653 class ShenandoahConcurrentRootsEvacUpdateTask : public AbstractGangTask { 1654 private: 1655 ShenandoahVMRoots<true /*concurrent*/> _vm_roots; 1656 ShenandoahClassLoaderDataRoots<true /*concurrent*/, false /*single threaded*/> _cld_roots; 1657 ShenandoahConcurrentStringDedupRoots _dedup_roots; 1658 1659 public: 1660 ShenandoahConcurrentRootsEvacUpdateTask(ShenandoahPhaseTimings::Phase phase) : 1661 AbstractGangTask("Shenandoah Evacuate/Update Concurrent Strong Roots Task"), 1662 _vm_roots(phase), 1663 _cld_roots(phase) {} 1664 1665 void work(uint worker_id) { 1666 ShenandoahConcurrentWorkerSession worker_session(worker_id); 1667 ShenandoahEvacOOMScope oom; 1668 { 1669 // vm_roots and weak_roots are OopStorage backed roots, concurrent iteration 1670 // may race against OopStorage::release() calls. 1671 ShenandoahEvacUpdateOopStorageRootsClosure cl; 1672 _vm_roots.oops_do<ShenandoahEvacUpdateOopStorageRootsClosure>(&cl, worker_id); 1673 } 1674 1675 { 1676 ShenandoahEvacuateUpdateRootsClosure<> cl; 1677 CLDToOopClosure clds(&cl, ClassLoaderData::_claim_strong); 1678 _cld_roots.cld_do(&clds, worker_id); 1679 } 1680 1681 { 1682 ShenandoahForwardedIsAliveClosure is_alive; 1683 ShenandoahEvacuateUpdateRootsClosure<MO_RELEASE> keep_alive; 1684 _dedup_roots.oops_do(&is_alive, &keep_alive, worker_id); 1685 } 1686 } 1687 }; 1688 1689 class ShenandoahEvacUpdateCleanupOopStorageRootsClosure : public BasicOopIterateClosure { 1690 private: 1691 ShenandoahHeap* const _heap; 1692 ShenandoahMarkingContext* const _mark_context; 1693 bool _evac_in_progress; 1694 Thread* const _thread; 1695 size_t _dead_counter; 1696 1697 public: 1698 ShenandoahEvacUpdateCleanupOopStorageRootsClosure(); 1699 void do_oop(oop* p); 1700 void do_oop(narrowOop* p); 1701 1702 size_t dead_counter() const; 1703 void reset_dead_counter(); 1704 }; 1705 1706 ShenandoahEvacUpdateCleanupOopStorageRootsClosure::ShenandoahEvacUpdateCleanupOopStorageRootsClosure() : 1707 _heap(ShenandoahHeap::heap()), 1708 _mark_context(ShenandoahHeap::heap()->marking_context()), 1709 _evac_in_progress(ShenandoahHeap::heap()->is_evacuation_in_progress()), 1710 _thread(Thread::current()), 1711 _dead_counter(0) { 1712 } 1713 1714 void ShenandoahEvacUpdateCleanupOopStorageRootsClosure::do_oop(oop* p) { 1715 const oop obj = RawAccess<>::oop_load(p); 1716 if (!CompressedOops::is_null(obj)) { 1717 if (!_mark_context->is_marked(obj)) { 1718 shenandoah_assert_correct(p, obj); 1719 oop old = Atomic::cmpxchg(p, obj, oop(NULL)); 1720 if (obj == old) { 1721 _dead_counter ++; 1722 } 1723 } else if (_evac_in_progress && _heap->in_collection_set(obj)) { 1724 oop resolved = ShenandoahBarrierSet::resolve_forwarded_not_null(obj); 1725 if (resolved == obj) { 1726 resolved = _heap->evacuate_object(obj, _thread); 1727 } 1728 Atomic::cmpxchg(p, obj, resolved); 1729 assert(_heap->cancelled_gc() || 1730 _mark_context->is_marked(resolved) && !_heap->in_collection_set(resolved), 1731 "Sanity"); 1732 } 1733 } 1734 } 1735 1736 void ShenandoahEvacUpdateCleanupOopStorageRootsClosure::do_oop(narrowOop* p) { 1737 ShouldNotReachHere(); 1738 } 1739 1740 size_t ShenandoahEvacUpdateCleanupOopStorageRootsClosure::dead_counter() const { 1741 return _dead_counter; 1742 } 1743 1744 void ShenandoahEvacUpdateCleanupOopStorageRootsClosure::reset_dead_counter() { 1745 _dead_counter = 0; 1746 } 1747 1748 class ShenandoahIsCLDAliveClosure : public CLDClosure { 1749 public: 1750 void do_cld(ClassLoaderData* cld) { 1751 cld->is_alive(); 1752 } 1753 }; 1754 1755 class ShenandoahIsNMethodAliveClosure: public NMethodClosure { 1756 public: 1757 void do_nmethod(nmethod* n) { 1758 n->is_unloading(); 1759 } 1760 }; 1761 1762 // This task not only evacuates/updates marked weak roots, but also "NULL" 1763 // dead weak roots. 1764 class ShenandoahConcurrentWeakRootsEvacUpdateTask : public AbstractGangTask { 1765 private: 1766 ShenandoahWeakRoot<true /*concurrent*/> _jni_roots; 1767 ShenandoahWeakRoot<true /*concurrent*/> _string_table_roots; 1768 ShenandoahWeakRoot<true /*concurrent*/> _resolved_method_table_roots; 1769 ShenandoahWeakRoot<true /*concurrent*/> _vm_roots; 1770 1771 // Roots related to concurrent class unloading 1772 ShenandoahClassLoaderDataRoots<true /* concurrent */, false /* single thread*/> 1773 _cld_roots; 1774 ShenandoahConcurrentNMethodIterator _nmethod_itr; 1775 bool _concurrent_class_unloading; 1776 1777 public: 1778 ShenandoahConcurrentWeakRootsEvacUpdateTask(ShenandoahPhaseTimings::Phase phase) : 1779 AbstractGangTask("Shenandoah Concurrent Weak Root Task"), 1780 _jni_roots(OopStorageSet::jni_weak(), phase, ShenandoahPhaseTimings::JNIWeakRoots), 1781 _string_table_roots(OopStorageSet::string_table_weak(), phase, ShenandoahPhaseTimings::StringTableRoots), 1782 _resolved_method_table_roots(OopStorageSet::resolved_method_table_weak(), phase, ShenandoahPhaseTimings::ResolvedMethodTableRoots), 1783 _vm_roots(OopStorageSet::vm_weak(), phase, ShenandoahPhaseTimings::VMWeakRoots), 1784 _cld_roots(phase), 1785 _nmethod_itr(ShenandoahCodeRoots::table()), 1786 _concurrent_class_unloading(ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) { 1787 StringTable::reset_dead_counter(); 1788 ResolvedMethodTable::reset_dead_counter(); 1789 if (_concurrent_class_unloading) { 1790 MutexLocker mu(CodeCache_lock, Mutex::_no_safepoint_check_flag); 1791 _nmethod_itr.nmethods_do_begin(); 1792 } 1793 } 1794 1795 ~ShenandoahConcurrentWeakRootsEvacUpdateTask() { 1796 StringTable::finish_dead_counter(); 1797 ResolvedMethodTable::finish_dead_counter(); 1798 if (_concurrent_class_unloading) { 1799 MutexLocker mu(CodeCache_lock, Mutex::_no_safepoint_check_flag); 1800 _nmethod_itr.nmethods_do_end(); 1801 } 1802 } 1803 1804 void work(uint worker_id) { 1805 ShenandoahConcurrentWorkerSession worker_session(worker_id); 1806 { 1807 ShenandoahEvacOOMScope oom; 1808 // jni_roots and weak_roots are OopStorage backed roots, concurrent iteration 1809 // may race against OopStorage::release() calls. 1810 ShenandoahEvacUpdateCleanupOopStorageRootsClosure cl; 1811 _jni_roots.oops_do(&cl, worker_id); 1812 _vm_roots.oops_do(&cl, worker_id); 1813 1814 cl.reset_dead_counter(); 1815 _string_table_roots.oops_do(&cl, worker_id); 1816 StringTable::inc_dead_counter(cl.dead_counter()); 1817 1818 cl.reset_dead_counter(); 1819 _resolved_method_table_roots.oops_do(&cl, worker_id); 1820 ResolvedMethodTable::inc_dead_counter(cl.dead_counter()); 1821 } 1822 1823 // If we are going to perform concurrent class unloading later on, we need to 1824 // cleanup the weak oops in CLD and determinate nmethod's unloading state, so that we 1825 // can cleanup immediate garbage sooner. 1826 if (_concurrent_class_unloading) { 1827 // Applies ShenandoahIsCLDAlive closure to CLDs, native barrier will either NULL the 1828 // CLD's holder or evacuate it. 1829 ShenandoahIsCLDAliveClosure is_cld_alive; 1830 _cld_roots.cld_do(&is_cld_alive, worker_id); 1831 1832 // Applies ShenandoahIsNMethodAliveClosure to registered nmethods. 1833 // The closure calls nmethod->is_unloading(). The is_unloading 1834 // state is cached, therefore, during concurrent class unloading phase, 1835 // we will not touch the metadata of unloading nmethods 1836 ShenandoahIsNMethodAliveClosure is_nmethod_alive; 1837 _nmethod_itr.nmethods_do(&is_nmethod_alive); 1838 } 1839 } 1840 }; 1841 1842 void ShenandoahHeap::op_weak_roots() { 1843 if (is_concurrent_weak_root_in_progress()) { 1844 // Concurrent weak root processing 1845 { 1846 ShenandoahTimingsTracker t(ShenandoahPhaseTimings::conc_weak_roots_work); 1847 ShenandoahGCWorkerPhase worker_phase(ShenandoahPhaseTimings::conc_weak_roots_work); 1848 ShenandoahConcurrentWeakRootsEvacUpdateTask task(ShenandoahPhaseTimings::conc_weak_roots_work); 1849 workers()->run_task(&task); 1850 if (!ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) { 1851 set_concurrent_weak_root_in_progress(false); 1852 } 1853 } 1854 1855 // Perform handshake to flush out dead oops 1856 { 1857 ShenandoahTimingsTracker t(ShenandoahPhaseTimings::conc_weak_roots_rendezvous); 1858 ShenandoahRendezvousClosure cl; 1859 Handshake::execute(&cl); 1860 } 1861 } 1862 } 1863 1864 void ShenandoahHeap::op_class_unloading() { 1865 assert (is_concurrent_weak_root_in_progress() && 1866 ShenandoahConcurrentRoots::should_do_concurrent_class_unloading(), 1867 "Checked by caller"); 1868 _unloader.unload(); 1869 set_concurrent_weak_root_in_progress(false); 1870 } 1871 1872 void ShenandoahHeap::op_strong_roots() { 1873 assert(is_concurrent_strong_root_in_progress(), "Checked by caller"); 1874 ShenandoahConcurrentRootsEvacUpdateTask task(ShenandoahPhaseTimings::conc_strong_roots); 1875 workers()->run_task(&task); 1876 set_concurrent_strong_root_in_progress(false); 1877 } 1878 1879 class ShenandoahResetUpdateRegionStateClosure : public ShenandoahHeapRegionClosure { 1880 private: 1881 ShenandoahMarkingContext* const _ctx; 1882 public: 1883 ShenandoahResetUpdateRegionStateClosure() : _ctx(ShenandoahHeap::heap()->marking_context()) {} 1884 1885 void heap_region_do(ShenandoahHeapRegion* r) { 1886 if (r->is_active()) { 1887 // Reset live data and set TAMS optimistically. We would recheck these under the pause 1888 // anyway to capture any updates that happened since now. 1889 r->clear_live_data(); 1890 _ctx->capture_top_at_mark_start(r); 1891 } 1892 } 1893 1894 bool is_thread_safe() { return true; } 1895 }; 1896 1897 void ShenandoahHeap::op_reset() { 1898 if (ShenandoahPacing) { 1899 pacer()->setup_for_reset(); 1900 } 1901 reset_mark_bitmap(); 1902 1903 ShenandoahResetUpdateRegionStateClosure cl; 1904 parallel_heap_region_iterate(&cl); 1905 } 1906 1907 void ShenandoahHeap::op_preclean() { 1908 if (ShenandoahPacing) { 1909 pacer()->setup_for_preclean(); 1910 } 1911 concurrent_mark()->preclean_weak_refs(); 1912 } 1913 1914 void ShenandoahHeap::op_full(GCCause::Cause cause) { 1915 ShenandoahMetricsSnapshot metrics; 1916 metrics.snap_before(); 1917 1918 full_gc()->do_it(cause); 1919 if (UseTLAB) { 1920 ShenandoahGCPhase phase(ShenandoahPhaseTimings::full_gc_resize_tlabs); 1921 resize_all_tlabs(); 1922 } 1923 1924 metrics.snap_after(); 1925 1926 if (metrics.is_good_progress()) { 1927 _progress_last_gc.set(); 1928 } else { 1929 // Nothing to do. Tell the allocation path that we have failed to make 1930 // progress, and it can finally fail. 1931 _progress_last_gc.unset(); 1932 } 1933 } 1934 1935 void ShenandoahHeap::op_degenerated(ShenandoahDegenPoint point) { 1936 // Degenerated GC is STW, but it can also fail. Current mechanics communicates 1937 // GC failure via cancelled_concgc() flag. So, if we detect the failure after 1938 // some phase, we have to upgrade the Degenerate GC to Full GC. 1939 1940 clear_cancelled_gc(); 1941 1942 ShenandoahMetricsSnapshot metrics; 1943 metrics.snap_before(); 1944 1945 switch (point) { 1946 // The cases below form the Duff's-like device: it describes the actual GC cycle, 1947 // but enters it at different points, depending on which concurrent phase had 1948 // degenerated. 1949 1950 case _degenerated_outside_cycle: 1951 // We have degenerated from outside the cycle, which means something is bad with 1952 // the heap, most probably heavy humongous fragmentation, or we are very low on free 1953 // space. It makes little sense to wait for Full GC to reclaim as much as it can, when 1954 // we can do the most aggressive degen cycle, which includes processing references and 1955 // class unloading, unless those features are explicitly disabled. 1956 // 1957 // Note that we can only do this for "outside-cycle" degens, otherwise we would risk 1958 // changing the cycle parameters mid-cycle during concurrent -> degenerated handover. 1959 set_process_references(heuristics()->can_process_references()); 1960 set_unload_classes(heuristics()->can_unload_classes()); 1961 1962 op_reset(); 1963 1964 op_init_mark(); 1965 if (cancelled_gc()) { 1966 op_degenerated_fail(); 1967 return; 1968 } 1969 1970 case _degenerated_mark: 1971 op_final_mark(); 1972 if (cancelled_gc()) { 1973 op_degenerated_fail(); 1974 return; 1975 } 1976 1977 if (!has_forwarded_objects() && ShenandoahConcurrentRoots::can_do_concurrent_class_unloading()) { 1978 // Disarm nmethods that armed for concurrent mark. On normal cycle, it would 1979 // be disarmed while conc-roots phase is running. 1980 // TODO: Call op_conc_roots() here instead 1981 ShenandoahCodeRoots::disarm_nmethods(); 1982 } 1983 1984 op_cleanup_early(); 1985 1986 case _degenerated_evac: 1987 // If heuristics thinks we should do the cycle, this flag would be set, 1988 // and we can do evacuation. Otherwise, it would be the shortcut cycle. 1989 if (is_evacuation_in_progress()) { 1990 1991 // Degeneration under oom-evac protocol might have left some objects in 1992 // collection set un-evacuated. Restart evacuation from the beginning to 1993 // capture all objects. For all the objects that are already evacuated, 1994 // it would be a simple check, which is supposed to be fast. This is also 1995 // safe to do even without degeneration, as CSet iterator is at beginning 1996 // in preparation for evacuation anyway. 1997 // 1998 // Before doing that, we need to make sure we never had any cset-pinned 1999 // regions. This may happen if allocation failure happened when evacuating 2000 // the about-to-be-pinned object, oom-evac protocol left the object in 2001 // the collection set, and then the pin reached the cset region. If we continue 2002 // the cycle here, we would trash the cset and alive objects in it. To avoid 2003 // it, we fail degeneration right away and slide into Full GC to recover. 2004 2005 { 2006 sync_pinned_region_status(); 2007 collection_set()->clear_current_index(); 2008 2009 ShenandoahHeapRegion* r; 2010 while ((r = collection_set()->next()) != NULL) { 2011 if (r->is_pinned()) { 2012 cancel_gc(GCCause::_shenandoah_upgrade_to_full_gc); 2013 op_degenerated_fail(); 2014 return; 2015 } 2016 } 2017 2018 collection_set()->clear_current_index(); 2019 } 2020 2021 op_stw_evac(); 2022 if (cancelled_gc()) { 2023 op_degenerated_fail(); 2024 return; 2025 } 2026 } 2027 2028 // If heuristics thinks we should do the cycle, this flag would be set, 2029 // and we need to do update-refs. Otherwise, it would be the shortcut cycle. 2030 if (has_forwarded_objects()) { 2031 op_init_updaterefs(); 2032 if (cancelled_gc()) { 2033 op_degenerated_fail(); 2034 return; 2035 } 2036 } 2037 2038 case _degenerated_updaterefs: 2039 if (has_forwarded_objects()) { 2040 op_final_updaterefs(); 2041 if (cancelled_gc()) { 2042 op_degenerated_fail(); 2043 return; 2044 } 2045 } 2046 2047 op_cleanup_complete(); 2048 break; 2049 2050 default: 2051 ShouldNotReachHere(); 2052 } 2053 2054 if (ShenandoahVerify) { 2055 verifier()->verify_after_degenerated(); 2056 } 2057 2058 if (VerifyAfterGC) { 2059 Universe::verify(); 2060 } 2061 2062 metrics.snap_after(); 2063 2064 // Check for futility and fail. There is no reason to do several back-to-back Degenerated cycles, 2065 // because that probably means the heap is overloaded and/or fragmented. 2066 if (!metrics.is_good_progress()) { 2067 _progress_last_gc.unset(); 2068 cancel_gc(GCCause::_shenandoah_upgrade_to_full_gc); 2069 op_degenerated_futile(); 2070 } else { 2071 _progress_last_gc.set(); 2072 } 2073 } 2074 2075 void ShenandoahHeap::op_degenerated_fail() { 2076 log_info(gc)("Cannot finish degeneration, upgrading to Full GC"); 2077 shenandoah_policy()->record_degenerated_upgrade_to_full(); 2078 op_full(GCCause::_shenandoah_upgrade_to_full_gc); 2079 } 2080 2081 void ShenandoahHeap::op_degenerated_futile() { 2082 shenandoah_policy()->record_degenerated_upgrade_to_full(); 2083 op_full(GCCause::_shenandoah_upgrade_to_full_gc); 2084 } 2085 2086 void ShenandoahHeap::force_satb_flush_all_threads() { 2087 if (!is_concurrent_mark_in_progress()) { 2088 // No need to flush SATBs 2089 return; 2090 } 2091 2092 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) { 2093 ShenandoahThreadLocalData::set_force_satb_flush(t, true); 2094 } 2095 // The threads are not "acquiring" their thread-local data, but it does not 2096 // hurt to "release" the updates here anyway. 2097 OrderAccess::fence(); 2098 } 2099 2100 void ShenandoahHeap::set_gc_state_all_threads(char state) { 2101 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) { 2102 ShenandoahThreadLocalData::set_gc_state(t, state); 2103 } 2104 } 2105 2106 void ShenandoahHeap::set_gc_state_mask(uint mask, bool value) { 2107 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should really be Shenandoah safepoint"); 2108 _gc_state.set_cond(mask, value); 2109 set_gc_state_all_threads(_gc_state.raw_value()); 2110 } 2111 2112 void ShenandoahHeap::set_concurrent_mark_in_progress(bool in_progress) { 2113 if (has_forwarded_objects()) { 2114 set_gc_state_mask(MARKING | UPDATEREFS, in_progress); 2115 } else { 2116 set_gc_state_mask(MARKING, in_progress); 2117 } 2118 ShenandoahBarrierSet::satb_mark_queue_set().set_active_all_threads(in_progress, !in_progress); 2119 } 2120 2121 void ShenandoahHeap::set_evacuation_in_progress(bool in_progress) { 2122 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Only call this at safepoint"); 2123 set_gc_state_mask(EVACUATION, in_progress); 2124 } 2125 2126 void ShenandoahHeap::set_concurrent_strong_root_in_progress(bool in_progress) { 2127 assert(ShenandoahConcurrentRoots::can_do_concurrent_roots(), "Why set the flag?"); 2128 if (in_progress) { 2129 _concurrent_strong_root_in_progress.set(); 2130 } else { 2131 _concurrent_strong_root_in_progress.unset(); 2132 } 2133 } 2134 2135 void ShenandoahHeap::set_concurrent_weak_root_in_progress(bool in_progress) { 2136 assert(ShenandoahConcurrentRoots::can_do_concurrent_roots(), "Why set the flag?"); 2137 if (in_progress) { 2138 _concurrent_weak_root_in_progress.set(); 2139 } else { 2140 _concurrent_weak_root_in_progress.unset(); 2141 } 2142 } 2143 2144 void ShenandoahHeap::ref_processing_init() { 2145 assert(_max_workers > 0, "Sanity"); 2146 2147 _ref_processor = 2148 new ReferenceProcessor(&_subject_to_discovery, // is_subject_to_discovery 2149 _ref_proc_mt_processing, // MT processing 2150 _max_workers, // Degree of MT processing 2151 _ref_proc_mt_discovery, // MT discovery 2152 _max_workers, // Degree of MT discovery 2153 false, // Reference discovery is not atomic 2154 NULL, // No closure, should be installed before use 2155 true); // Scale worker threads 2156 2157 shenandoah_assert_rp_isalive_not_installed(); 2158 } 2159 2160 GCTracer* ShenandoahHeap::tracer() { 2161 return shenandoah_policy()->tracer(); 2162 } 2163 2164 size_t ShenandoahHeap::tlab_used(Thread* thread) const { 2165 return _free_set->used(); 2166 } 2167 2168 bool ShenandoahHeap::try_cancel_gc() { 2169 while (true) { 2170 jbyte prev = _cancelled_gc.cmpxchg(CANCELLED, CANCELLABLE); 2171 if (prev == CANCELLABLE) return true; 2172 else if (prev == CANCELLED) return false; 2173 assert(ShenandoahSuspendibleWorkers, "should not get here when not using suspendible workers"); 2174 assert(prev == NOT_CANCELLED, "must be NOT_CANCELLED"); 2175 if (Thread::current()->is_Java_thread()) { 2176 // We need to provide a safepoint here, otherwise we might 2177 // spin forever if a SP is pending. 2178 ThreadBlockInVM sp(JavaThread::current()); 2179 SpinPause(); 2180 } 2181 } 2182 } 2183 2184 void ShenandoahHeap::cancel_gc(GCCause::Cause cause) { 2185 if (try_cancel_gc()) { 2186 FormatBuffer<> msg("Cancelling GC: %s", GCCause::to_string(cause)); 2187 log_info(gc)("%s", msg.buffer()); 2188 Events::log(Thread::current(), "%s", msg.buffer()); 2189 } 2190 } 2191 2192 uint ShenandoahHeap::max_workers() { 2193 return _max_workers; 2194 } 2195 2196 void ShenandoahHeap::stop() { 2197 // The shutdown sequence should be able to terminate when GC is running. 2198 2199 // Step 0. Notify policy to disable event recording. 2200 _shenandoah_policy->record_shutdown(); 2201 2202 // Step 1. Notify control thread that we are in shutdown. 2203 // Note that we cannot do that with stop(), because stop() is blocking and waits for the actual shutdown. 2204 // Doing stop() here would wait for the normal GC cycle to complete, never falling through to cancel below. 2205 control_thread()->prepare_for_graceful_shutdown(); 2206 2207 // Step 2. Notify GC workers that we are cancelling GC. 2208 cancel_gc(GCCause::_shenandoah_stop_vm); 2209 2210 // Step 3. Wait until GC worker exits normally. 2211 control_thread()->stop(); 2212 2213 // Step 4. Stop String Dedup thread if it is active 2214 if (ShenandoahStringDedup::is_enabled()) { 2215 ShenandoahStringDedup::stop(); 2216 } 2217 } 2218 2219 void ShenandoahHeap::stw_unload_classes(bool full_gc) { 2220 if (!unload_classes()) return; 2221 2222 // Unload classes and purge SystemDictionary. 2223 { 2224 ShenandoahGCPhase phase(full_gc ? 2225 ShenandoahPhaseTimings::full_gc_purge_class_unload : 2226 ShenandoahPhaseTimings::purge_class_unload); 2227 bool purged_class = SystemDictionary::do_unloading(gc_timer()); 2228 2229 ShenandoahIsAliveSelector is_alive; 2230 uint num_workers = _workers->active_workers(); 2231 ShenandoahClassUnloadingTask unlink_task(is_alive.is_alive_closure(), num_workers, purged_class); 2232 _workers->run_task(&unlink_task); 2233 } 2234 2235 { 2236 ShenandoahGCPhase phase(full_gc ? 2237 ShenandoahPhaseTimings::full_gc_purge_cldg : 2238 ShenandoahPhaseTimings::purge_cldg); 2239 ClassLoaderDataGraph::purge(); 2240 } 2241 // Resize and verify metaspace 2242 MetaspaceGC::compute_new_size(); 2243 MetaspaceUtils::verify_metrics(); 2244 } 2245 2246 // Weak roots are either pre-evacuated (final mark) or updated (final updaterefs), 2247 // so they should not have forwarded oops. 2248 // However, we do need to "null" dead oops in the roots, if can not be done 2249 // in concurrent cycles. 2250 void ShenandoahHeap::stw_process_weak_roots(bool full_gc) { 2251 ShenandoahGCPhase root_phase(full_gc ? 2252 ShenandoahPhaseTimings::full_gc_purge : 2253 ShenandoahPhaseTimings::purge); 2254 uint num_workers = _workers->active_workers(); 2255 ShenandoahPhaseTimings::Phase timing_phase = full_gc ? 2256 ShenandoahPhaseTimings::full_gc_purge_weak_par : 2257 ShenandoahPhaseTimings::purge_weak_par; 2258 ShenandoahGCPhase phase(timing_phase); 2259 ShenandoahGCWorkerPhase worker_phase(timing_phase); 2260 2261 // Cleanup weak roots 2262 if (has_forwarded_objects()) { 2263 ShenandoahForwardedIsAliveClosure is_alive; 2264 ShenandoahUpdateRefsClosure keep_alive; 2265 ShenandoahParallelWeakRootsCleaningTask<ShenandoahForwardedIsAliveClosure, ShenandoahUpdateRefsClosure> 2266 cleaning_task(timing_phase, &is_alive, &keep_alive, num_workers, !ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()); 2267 _workers->run_task(&cleaning_task); 2268 } else { 2269 ShenandoahIsAliveClosure is_alive; 2270 #ifdef ASSERT 2271 ShenandoahAssertNotForwardedClosure verify_cl; 2272 ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, ShenandoahAssertNotForwardedClosure> 2273 cleaning_task(timing_phase, &is_alive, &verify_cl, num_workers, !ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()); 2274 #else 2275 ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, DoNothingClosure> 2276 cleaning_task(timing_phase, &is_alive, &do_nothing_cl, num_workers, !ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()); 2277 #endif 2278 _workers->run_task(&cleaning_task); 2279 } 2280 } 2281 2282 void ShenandoahHeap::parallel_cleaning(bool full_gc) { 2283 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint"); 2284 stw_process_weak_roots(full_gc); 2285 if (!ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) { 2286 stw_unload_classes(full_gc); 2287 } 2288 } 2289 2290 void ShenandoahHeap::set_has_forwarded_objects(bool cond) { 2291 set_gc_state_mask(HAS_FORWARDED, cond); 2292 } 2293 2294 void ShenandoahHeap::set_process_references(bool pr) { 2295 _process_references.set_cond(pr); 2296 } 2297 2298 void ShenandoahHeap::set_unload_classes(bool uc) { 2299 _unload_classes.set_cond(uc); 2300 } 2301 2302 bool ShenandoahHeap::process_references() const { 2303 return _process_references.is_set(); 2304 } 2305 2306 bool ShenandoahHeap::unload_classes() const { 2307 return _unload_classes.is_set(); 2308 } 2309 2310 address ShenandoahHeap::in_cset_fast_test_addr() { 2311 ShenandoahHeap* heap = ShenandoahHeap::heap(); 2312 assert(heap->collection_set() != NULL, "Sanity"); 2313 return (address) heap->collection_set()->biased_map_address(); 2314 } 2315 2316 address ShenandoahHeap::cancelled_gc_addr() { 2317 return (address) ShenandoahHeap::heap()->_cancelled_gc.addr_of(); 2318 } 2319 2320 address ShenandoahHeap::gc_state_addr() { 2321 return (address) ShenandoahHeap::heap()->_gc_state.addr_of(); 2322 } 2323 2324 size_t ShenandoahHeap::bytes_allocated_since_gc_start() { 2325 return Atomic::load_acquire(&_bytes_allocated_since_gc_start); 2326 } 2327 2328 void ShenandoahHeap::reset_bytes_allocated_since_gc_start() { 2329 Atomic::release_store_fence(&_bytes_allocated_since_gc_start, (size_t)0); 2330 } 2331 2332 void ShenandoahHeap::set_degenerated_gc_in_progress(bool in_progress) { 2333 _degenerated_gc_in_progress.set_cond(in_progress); 2334 } 2335 2336 void ShenandoahHeap::set_full_gc_in_progress(bool in_progress) { 2337 _full_gc_in_progress.set_cond(in_progress); 2338 } 2339 2340 void ShenandoahHeap::set_full_gc_move_in_progress(bool in_progress) { 2341 assert (is_full_gc_in_progress(), "should be"); 2342 _full_gc_move_in_progress.set_cond(in_progress); 2343 } 2344 2345 void ShenandoahHeap::set_update_refs_in_progress(bool in_progress) { 2346 set_gc_state_mask(UPDATEREFS, in_progress); 2347 } 2348 2349 void ShenandoahHeap::register_nmethod(nmethod* nm) { 2350 ShenandoahCodeRoots::register_nmethod(nm); 2351 } 2352 2353 void ShenandoahHeap::unregister_nmethod(nmethod* nm) { 2354 ShenandoahCodeRoots::unregister_nmethod(nm); 2355 } 2356 2357 void ShenandoahHeap::flush_nmethod(nmethod* nm) { 2358 ShenandoahCodeRoots::flush_nmethod(nm); 2359 } 2360 2361 oop ShenandoahHeap::pin_object(JavaThread* thr, oop o) { 2362 heap_region_containing(o)->record_pin(); 2363 return o; 2364 } 2365 2366 void ShenandoahHeap::unpin_object(JavaThread* thr, oop o) { 2367 heap_region_containing(o)->record_unpin(); 2368 } 2369 2370 void ShenandoahHeap::sync_pinned_region_status() { 2371 ShenandoahHeapLocker locker(lock()); 2372 2373 for (size_t i = 0; i < num_regions(); i++) { 2374 ShenandoahHeapRegion *r = get_region(i); 2375 if (r->is_active()) { 2376 if (r->is_pinned()) { 2377 if (r->pin_count() == 0) { 2378 r->make_unpinned(); 2379 } 2380 } else { 2381 if (r->pin_count() > 0) { 2382 r->make_pinned(); 2383 } 2384 } 2385 } 2386 } 2387 2388 assert_pinned_region_status(); 2389 } 2390 2391 #ifdef ASSERT 2392 void ShenandoahHeap::assert_pinned_region_status() { 2393 for (size_t i = 0; i < num_regions(); i++) { 2394 ShenandoahHeapRegion* r = get_region(i); 2395 assert((r->is_pinned() && r->pin_count() > 0) || (!r->is_pinned() && r->pin_count() == 0), 2396 "Region " SIZE_FORMAT " pinning status is inconsistent", i); 2397 } 2398 } 2399 #endif 2400 2401 ConcurrentGCTimer* ShenandoahHeap::gc_timer() const { 2402 return _gc_timer; 2403 } 2404 2405 void ShenandoahHeap::prepare_concurrent_roots() { 2406 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint"); 2407 if (ShenandoahConcurrentRoots::should_do_concurrent_roots()) { 2408 set_concurrent_strong_root_in_progress(!collection_set()->is_empty()); 2409 set_concurrent_weak_root_in_progress(true); 2410 } 2411 } 2412 2413 void ShenandoahHeap::prepare_concurrent_unloading() { 2414 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint"); 2415 if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) { 2416 _unloader.prepare(); 2417 } 2418 } 2419 2420 void ShenandoahHeap::finish_concurrent_unloading() { 2421 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint"); 2422 if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) { 2423 _unloader.finish(); 2424 } 2425 } 2426 2427 #ifdef ASSERT 2428 void ShenandoahHeap::assert_gc_workers(uint nworkers) { 2429 assert(nworkers > 0 && nworkers <= max_workers(), "Sanity"); 2430 2431 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) { 2432 if (UseDynamicNumberOfGCThreads) { 2433 assert(nworkers <= ParallelGCThreads, "Cannot use more than it has"); 2434 } else { 2435 // Use ParallelGCThreads inside safepoints 2436 assert(nworkers == ParallelGCThreads, "Use ParallelGCThreads within safepoints"); 2437 } 2438 } else { 2439 if (UseDynamicNumberOfGCThreads) { 2440 assert(nworkers <= ConcGCThreads, "Cannot use more than it has"); 2441 } else { 2442 // Use ConcGCThreads outside safepoints 2443 assert(nworkers == ConcGCThreads, "Use ConcGCThreads outside safepoints"); 2444 } 2445 } 2446 } 2447 #endif 2448 2449 ShenandoahVerifier* ShenandoahHeap::verifier() { 2450 guarantee(ShenandoahVerify, "Should be enabled"); 2451 assert (_verifier != NULL, "sanity"); 2452 return _verifier; 2453 } 2454 2455 template<class T> 2456 class ShenandoahUpdateHeapRefsTask : public AbstractGangTask { 2457 private: 2458 T cl; 2459 ShenandoahHeap* _heap; 2460 ShenandoahRegionIterator* _regions; 2461 bool _concurrent; 2462 public: 2463 ShenandoahUpdateHeapRefsTask(ShenandoahRegionIterator* regions, bool concurrent) : 2464 AbstractGangTask("Concurrent Update References Task"), 2465 cl(T()), 2466 _heap(ShenandoahHeap::heap()), 2467 _regions(regions), 2468 _concurrent(concurrent) { 2469 } 2470 2471 void work(uint worker_id) { 2472 if (_concurrent) { 2473 ShenandoahConcurrentWorkerSession worker_session(worker_id); 2474 ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers); 2475 do_work(); 2476 } else { 2477 ShenandoahParallelWorkerSession worker_session(worker_id); 2478 do_work(); 2479 } 2480 } 2481 2482 private: 2483 void do_work() { 2484 ShenandoahHeapRegion* r = _regions->next(); 2485 ShenandoahMarkingContext* const ctx = _heap->complete_marking_context(); 2486 while (r != NULL) { 2487 HeapWord* update_watermark = r->get_update_watermark(); 2488 assert (update_watermark >= r->bottom(), "sanity"); 2489 if (r->is_active() && !r->is_cset()) { 2490 _heap->marked_object_oop_iterate(r, &cl, update_watermark); 2491 } 2492 if (ShenandoahPacing) { 2493 _heap->pacer()->report_updaterefs(pointer_delta(update_watermark, r->bottom())); 2494 } 2495 if (_heap->check_cancelled_gc_and_yield(_concurrent)) { 2496 return; 2497 } 2498 r = _regions->next(); 2499 } 2500 } 2501 }; 2502 2503 void ShenandoahHeap::update_heap_references(bool concurrent) { 2504 ShenandoahUpdateHeapRefsTask<ShenandoahUpdateHeapRefsClosure> task(&_update_refs_iterator, concurrent); 2505 workers()->run_task(&task); 2506 } 2507 2508 void ShenandoahHeap::op_init_updaterefs() { 2509 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint"); 2510 2511 set_evacuation_in_progress(false); 2512 2513 { 2514 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_refs_retire_gclabs); 2515 retire_and_reset_gclabs(); 2516 } 2517 2518 if (ShenandoahVerify) { 2519 if (!is_degenerated_gc_in_progress()) { 2520 verifier()->verify_roots_in_to_space_except(ShenandoahRootVerifier::ThreadRoots); 2521 } 2522 verifier()->verify_before_updaterefs(); 2523 } 2524 2525 set_update_refs_in_progress(true); 2526 2527 _update_refs_iterator.reset(); 2528 2529 if (ShenandoahPacing) { 2530 pacer()->setup_for_updaterefs(); 2531 } 2532 } 2533 2534 class ShenandoahFinalUpdateRefsUpdateRegionStateClosure : public ShenandoahHeapRegionClosure { 2535 private: 2536 ShenandoahHeapLock* const _lock; 2537 2538 public: 2539 ShenandoahFinalUpdateRefsUpdateRegionStateClosure() : _lock(ShenandoahHeap::heap()->lock()) {} 2540 2541 void heap_region_do(ShenandoahHeapRegion* r) { 2542 // Drop unnecessary "pinned" state from regions that does not have CP marks 2543 // anymore, as this would allow trashing them. 2544 2545 if (r->is_active()) { 2546 if (r->is_pinned()) { 2547 if (r->pin_count() == 0) { 2548 ShenandoahHeapLocker locker(_lock); 2549 r->make_unpinned(); 2550 } 2551 } else { 2552 if (r->pin_count() > 0) { 2553 ShenandoahHeapLocker locker(_lock); 2554 r->make_pinned(); 2555 } 2556 } 2557 } 2558 } 2559 2560 bool is_thread_safe() { return true; } 2561 }; 2562 2563 void ShenandoahHeap::op_final_updaterefs() { 2564 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint"); 2565 2566 finish_concurrent_unloading(); 2567 2568 // Check if there is left-over work, and finish it 2569 if (_update_refs_iterator.has_next()) { 2570 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_finish_work); 2571 2572 // Finish updating references where we left off. 2573 clear_cancelled_gc(); 2574 update_heap_references(false); 2575 } 2576 2577 // Clear cancelled GC, if set. On cancellation path, the block before would handle 2578 // everything. On degenerated paths, cancelled gc would not be set anyway. 2579 if (cancelled_gc()) { 2580 clear_cancelled_gc(); 2581 } 2582 assert(!cancelled_gc(), "Should have been done right before"); 2583 2584 if (ShenandoahVerify && !is_degenerated_gc_in_progress()) { 2585 verifier()->verify_roots_in_to_space_except(ShenandoahRootVerifier::ThreadRoots); 2586 } 2587 2588 if (is_degenerated_gc_in_progress()) { 2589 concurrent_mark()->update_roots(ShenandoahPhaseTimings::degen_gc_update_roots); 2590 } else { 2591 concurrent_mark()->update_thread_roots(ShenandoahPhaseTimings::final_update_refs_roots); 2592 } 2593 2594 // Has to be done before cset is clear 2595 if (ShenandoahVerify) { 2596 verifier()->verify_roots_in_to_space(); 2597 } 2598 2599 { 2600 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_update_region_states); 2601 ShenandoahFinalUpdateRefsUpdateRegionStateClosure cl; 2602 parallel_heap_region_iterate(&cl); 2603 2604 assert_pinned_region_status(); 2605 } 2606 2607 { 2608 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_trash_cset); 2609 trash_cset_regions(); 2610 } 2611 2612 set_has_forwarded_objects(false); 2613 set_update_refs_in_progress(false); 2614 2615 if (ShenandoahVerify) { 2616 verifier()->verify_after_updaterefs(); 2617 } 2618 2619 if (VerifyAfterGC) { 2620 Universe::verify(); 2621 } 2622 2623 { 2624 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_rebuild_freeset); 2625 ShenandoahHeapLocker locker(lock()); 2626 _free_set->rebuild(); 2627 } 2628 } 2629 2630 void ShenandoahHeap::print_extended_on(outputStream *st) const { 2631 print_on(st); 2632 print_heap_regions_on(st); 2633 } 2634 2635 bool ShenandoahHeap::is_bitmap_slice_committed(ShenandoahHeapRegion* r, bool skip_self) { 2636 size_t slice = r->index() / _bitmap_regions_per_slice; 2637 2638 size_t regions_from = _bitmap_regions_per_slice * slice; 2639 size_t regions_to = MIN2(num_regions(), _bitmap_regions_per_slice * (slice + 1)); 2640 for (size_t g = regions_from; g < regions_to; g++) { 2641 assert (g / _bitmap_regions_per_slice == slice, "same slice"); 2642 if (skip_self && g == r->index()) continue; 2643 if (get_region(g)->is_committed()) { 2644 return true; 2645 } 2646 } 2647 return false; 2648 } 2649 2650 bool ShenandoahHeap::commit_bitmap_slice(ShenandoahHeapRegion* r) { 2651 shenandoah_assert_heaplocked(); 2652 2653 // Bitmaps in special regions do not need commits 2654 if (_bitmap_region_special) { 2655 return true; 2656 } 2657 2658 if (is_bitmap_slice_committed(r, true)) { 2659 // Some other region from the group is already committed, meaning the bitmap 2660 // slice is already committed, we exit right away. 2661 return true; 2662 } 2663 2664 // Commit the bitmap slice: 2665 size_t slice = r->index() / _bitmap_regions_per_slice; 2666 size_t off = _bitmap_bytes_per_slice * slice; 2667 size_t len = _bitmap_bytes_per_slice; 2668 char* start = (char*) _bitmap_region.start() + off; 2669 2670 if (!os::commit_memory(start, len, false)) { 2671 return false; 2672 } 2673 2674 if (AlwaysPreTouch) { 2675 os::pretouch_memory(start, start + len, _pretouch_bitmap_page_size); 2676 } 2677 2678 return true; 2679 } 2680 2681 bool ShenandoahHeap::uncommit_bitmap_slice(ShenandoahHeapRegion *r) { 2682 shenandoah_assert_heaplocked(); 2683 2684 // Bitmaps in special regions do not need uncommits 2685 if (_bitmap_region_special) { 2686 return true; 2687 } 2688 2689 if (is_bitmap_slice_committed(r, true)) { 2690 // Some other region from the group is still committed, meaning the bitmap 2691 // slice is should stay committed, exit right away. 2692 return true; 2693 } 2694 2695 // Uncommit the bitmap slice: 2696 size_t slice = r->index() / _bitmap_regions_per_slice; 2697 size_t off = _bitmap_bytes_per_slice * slice; 2698 size_t len = _bitmap_bytes_per_slice; 2699 if (!os::uncommit_memory((char*)_bitmap_region.start() + off, len)) { 2700 return false; 2701 } 2702 return true; 2703 } 2704 2705 void ShenandoahHeap::safepoint_synchronize_begin() { 2706 if (ShenandoahSuspendibleWorkers || UseStringDeduplication) { 2707 SuspendibleThreadSet::synchronize(); 2708 } 2709 } 2710 2711 void ShenandoahHeap::safepoint_synchronize_end() { 2712 if (ShenandoahSuspendibleWorkers || UseStringDeduplication) { 2713 SuspendibleThreadSet::desynchronize(); 2714 } 2715 } 2716 2717 void ShenandoahHeap::vmop_entry_init_mark() { 2718 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters()); 2719 ShenandoahTimingsTracker timing(ShenandoahPhaseTimings::init_mark_gross); 2720 2721 try_inject_alloc_failure(); 2722 VM_ShenandoahInitMark op; 2723 VMThread::execute(&op); // jump to entry_init_mark() under safepoint 2724 } 2725 2726 void ShenandoahHeap::vmop_entry_final_mark() { 2727 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters()); 2728 ShenandoahTimingsTracker timing(ShenandoahPhaseTimings::final_mark_gross); 2729 2730 try_inject_alloc_failure(); 2731 VM_ShenandoahFinalMarkStartEvac op; 2732 VMThread::execute(&op); // jump to entry_final_mark under safepoint 2733 } 2734 2735 void ShenandoahHeap::vmop_entry_init_updaterefs() { 2736 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters()); 2737 ShenandoahTimingsTracker timing(ShenandoahPhaseTimings::init_update_refs_gross); 2738 2739 try_inject_alloc_failure(); 2740 VM_ShenandoahInitUpdateRefs op; 2741 VMThread::execute(&op); 2742 } 2743 2744 void ShenandoahHeap::vmop_entry_final_updaterefs() { 2745 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters()); 2746 ShenandoahTimingsTracker timing(ShenandoahPhaseTimings::final_update_refs_gross); 2747 2748 try_inject_alloc_failure(); 2749 VM_ShenandoahFinalUpdateRefs op; 2750 VMThread::execute(&op); 2751 } 2752 2753 void ShenandoahHeap::vmop_entry_full(GCCause::Cause cause) { 2754 TraceCollectorStats tcs(monitoring_support()->full_stw_collection_counters()); 2755 ShenandoahTimingsTracker timing(ShenandoahPhaseTimings::full_gc_gross); 2756 2757 try_inject_alloc_failure(); 2758 VM_ShenandoahFullGC op(cause); 2759 VMThread::execute(&op); 2760 } 2761 2762 void ShenandoahHeap::vmop_degenerated(ShenandoahDegenPoint point) { 2763 TraceCollectorStats tcs(monitoring_support()->full_stw_collection_counters()); 2764 ShenandoahTimingsTracker timing(ShenandoahPhaseTimings::degen_gc_gross); 2765 2766 VM_ShenandoahDegeneratedGC degenerated_gc((int)point); 2767 VMThread::execute(°enerated_gc); 2768 } 2769 2770 void ShenandoahHeap::entry_init_mark() { 2771 const char* msg = init_mark_event_message(); 2772 ShenandoahPausePhase gc_phase(msg, ShenandoahPhaseTimings::init_mark); 2773 EventMark em("%s", msg); 2774 2775 ShenandoahWorkerScope scope(workers(), 2776 ShenandoahWorkerPolicy::calc_workers_for_init_marking(), 2777 "init marking"); 2778 2779 op_init_mark(); 2780 } 2781 2782 void ShenandoahHeap::entry_final_mark() { 2783 const char* msg = final_mark_event_message(); 2784 ShenandoahPausePhase gc_phase(msg, ShenandoahPhaseTimings::final_mark); 2785 EventMark em("%s", msg); 2786 2787 ShenandoahWorkerScope scope(workers(), 2788 ShenandoahWorkerPolicy::calc_workers_for_final_marking(), 2789 "final marking"); 2790 2791 op_final_mark(); 2792 } 2793 2794 void ShenandoahHeap::entry_init_updaterefs() { 2795 static const char* msg = "Pause Init Update Refs"; 2796 ShenandoahPausePhase gc_phase(msg, ShenandoahPhaseTimings::init_update_refs); 2797 EventMark em("%s", msg); 2798 2799 // No workers used in this phase, no setup required 2800 2801 op_init_updaterefs(); 2802 } 2803 2804 void ShenandoahHeap::entry_final_updaterefs() { 2805 static const char* msg = "Pause Final Update Refs"; 2806 ShenandoahPausePhase gc_phase(msg, ShenandoahPhaseTimings::final_update_refs); 2807 EventMark em("%s", msg); 2808 2809 ShenandoahWorkerScope scope(workers(), 2810 ShenandoahWorkerPolicy::calc_workers_for_final_update_ref(), 2811 "final reference update"); 2812 2813 op_final_updaterefs(); 2814 } 2815 2816 void ShenandoahHeap::entry_full(GCCause::Cause cause) { 2817 static const char* msg = "Pause Full"; 2818 ShenandoahPausePhase gc_phase(msg, ShenandoahPhaseTimings::full_gc, true /* log_heap_usage */); 2819 EventMark em("%s", msg); 2820 2821 ShenandoahWorkerScope scope(workers(), 2822 ShenandoahWorkerPolicy::calc_workers_for_fullgc(), 2823 "full gc"); 2824 2825 op_full(cause); 2826 } 2827 2828 void ShenandoahHeap::entry_degenerated(int point) { 2829 ShenandoahDegenPoint dpoint = (ShenandoahDegenPoint)point; 2830 const char* msg = degen_event_message(dpoint); 2831 ShenandoahPausePhase gc_phase(msg, ShenandoahPhaseTimings::degen_gc, true /* log_heap_usage */); 2832 EventMark em("%s", msg); 2833 2834 ShenandoahWorkerScope scope(workers(), 2835 ShenandoahWorkerPolicy::calc_workers_for_stw_degenerated(), 2836 "stw degenerated gc"); 2837 2838 set_degenerated_gc_in_progress(true); 2839 op_degenerated(dpoint); 2840 set_degenerated_gc_in_progress(false); 2841 } 2842 2843 void ShenandoahHeap::entry_mark() { 2844 TraceCollectorStats tcs(monitoring_support()->concurrent_collection_counters()); 2845 2846 const char* msg = conc_mark_event_message(); 2847 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_mark); 2848 EventMark em("%s", msg); 2849 2850 ShenandoahWorkerScope scope(workers(), 2851 ShenandoahWorkerPolicy::calc_workers_for_conc_marking(), 2852 "concurrent marking"); 2853 2854 try_inject_alloc_failure(); 2855 op_mark(); 2856 } 2857 2858 void ShenandoahHeap::entry_evac() { 2859 TraceCollectorStats tcs(monitoring_support()->concurrent_collection_counters()); 2860 2861 static const char* msg = "Concurrent evacuation"; 2862 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_evac); 2863 EventMark em("%s", msg); 2864 2865 ShenandoahWorkerScope scope(workers(), 2866 ShenandoahWorkerPolicy::calc_workers_for_conc_evac(), 2867 "concurrent evacuation"); 2868 2869 try_inject_alloc_failure(); 2870 op_conc_evac(); 2871 } 2872 2873 void ShenandoahHeap::entry_updaterefs() { 2874 static const char* msg = "Concurrent update references"; 2875 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_update_refs); 2876 EventMark em("%s", msg); 2877 2878 ShenandoahWorkerScope scope(workers(), 2879 ShenandoahWorkerPolicy::calc_workers_for_conc_update_ref(), 2880 "concurrent reference update"); 2881 2882 try_inject_alloc_failure(); 2883 op_updaterefs(); 2884 } 2885 2886 void ShenandoahHeap::entry_weak_roots() { 2887 static const char* msg = "Concurrent weak roots"; 2888 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_weak_roots); 2889 EventMark em("%s", msg); 2890 2891 ShenandoahWorkerScope scope(workers(), 2892 ShenandoahWorkerPolicy::calc_workers_for_conc_root_processing(), 2893 "concurrent weak root"); 2894 2895 try_inject_alloc_failure(); 2896 op_weak_roots(); 2897 } 2898 2899 void ShenandoahHeap::entry_class_unloading() { 2900 static const char* msg = "Concurrent class unloading"; 2901 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_class_unload); 2902 EventMark em("%s", msg); 2903 2904 ShenandoahWorkerScope scope(workers(), 2905 ShenandoahWorkerPolicy::calc_workers_for_conc_root_processing(), 2906 "concurrent class unloading"); 2907 2908 try_inject_alloc_failure(); 2909 op_class_unloading(); 2910 } 2911 2912 void ShenandoahHeap::entry_strong_roots() { 2913 static const char* msg = "Concurrent strong roots"; 2914 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_strong_roots); 2915 EventMark em("%s", msg); 2916 2917 ShenandoahGCWorkerPhase worker_phase(ShenandoahPhaseTimings::conc_strong_roots); 2918 2919 ShenandoahWorkerScope scope(workers(), 2920 ShenandoahWorkerPolicy::calc_workers_for_conc_root_processing(), 2921 "concurrent strong root"); 2922 2923 try_inject_alloc_failure(); 2924 op_strong_roots(); 2925 } 2926 2927 void ShenandoahHeap::entry_cleanup_early() { 2928 static const char* msg = "Concurrent cleanup"; 2929 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_cleanup_early, true /* log_heap_usage */); 2930 EventMark em("%s", msg); 2931 2932 // This phase does not use workers, no need for setup 2933 2934 try_inject_alloc_failure(); 2935 op_cleanup_early(); 2936 } 2937 2938 void ShenandoahHeap::entry_cleanup_complete() { 2939 static const char* msg = "Concurrent cleanup"; 2940 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_cleanup_complete, true /* log_heap_usage */); 2941 EventMark em("%s", msg); 2942 2943 // This phase does not use workers, no need for setup 2944 2945 try_inject_alloc_failure(); 2946 op_cleanup_complete(); 2947 } 2948 2949 void ShenandoahHeap::entry_reset() { 2950 static const char* msg = "Concurrent reset"; 2951 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_reset); 2952 EventMark em("%s", msg); 2953 2954 ShenandoahWorkerScope scope(workers(), 2955 ShenandoahWorkerPolicy::calc_workers_for_conc_reset(), 2956 "concurrent reset"); 2957 2958 try_inject_alloc_failure(); 2959 op_reset(); 2960 } 2961 2962 void ShenandoahHeap::entry_preclean() { 2963 if (ShenandoahPreclean && process_references()) { 2964 static const char* msg = "Concurrent precleaning"; 2965 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_preclean); 2966 EventMark em("%s", msg); 2967 2968 ShenandoahWorkerScope scope(workers(), 2969 ShenandoahWorkerPolicy::calc_workers_for_conc_preclean(), 2970 "concurrent preclean", 2971 /* check_workers = */ false); 2972 2973 try_inject_alloc_failure(); 2974 op_preclean(); 2975 } 2976 } 2977 2978 void ShenandoahHeap::entry_uncommit(double shrink_before) { 2979 static const char *msg = "Concurrent uncommit"; 2980 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_uncommit, true /* log_heap_usage */); 2981 EventMark em("%s", msg); 2982 2983 op_uncommit(shrink_before); 2984 } 2985 2986 void ShenandoahHeap::try_inject_alloc_failure() { 2987 if (ShenandoahAllocFailureALot && !cancelled_gc() && ((os::random() % 1000) > 950)) { 2988 _inject_alloc_failure.set(); 2989 os::naked_short_sleep(1); 2990 if (cancelled_gc()) { 2991 log_info(gc)("Allocation failure was successfully injected"); 2992 } 2993 } 2994 } 2995 2996 bool ShenandoahHeap::should_inject_alloc_failure() { 2997 return _inject_alloc_failure.is_set() && _inject_alloc_failure.try_unset(); 2998 } 2999 3000 void ShenandoahHeap::initialize_serviceability() { 3001 _memory_pool = new ShenandoahMemoryPool(this); 3002 _cycle_memory_manager.add_pool(_memory_pool); 3003 _stw_memory_manager.add_pool(_memory_pool); 3004 } 3005 3006 GrowableArray<GCMemoryManager*> ShenandoahHeap::memory_managers() { 3007 GrowableArray<GCMemoryManager*> memory_managers(2); 3008 memory_managers.append(&_cycle_memory_manager); 3009 memory_managers.append(&_stw_memory_manager); 3010 return memory_managers; 3011 } 3012 3013 GrowableArray<MemoryPool*> ShenandoahHeap::memory_pools() { 3014 GrowableArray<MemoryPool*> memory_pools(1); 3015 memory_pools.append(_memory_pool); 3016 return memory_pools; 3017 } 3018 3019 MemoryUsage ShenandoahHeap::memory_usage() { 3020 return _memory_pool->get_memory_usage(); 3021 } 3022 3023 ShenandoahRegionIterator::ShenandoahRegionIterator() : 3024 _heap(ShenandoahHeap::heap()), 3025 _index(0) {} 3026 3027 ShenandoahRegionIterator::ShenandoahRegionIterator(ShenandoahHeap* heap) : 3028 _heap(heap), 3029 _index(0) {} 3030 3031 void ShenandoahRegionIterator::reset() { 3032 _index = 0; 3033 } 3034 3035 bool ShenandoahRegionIterator::has_next() const { 3036 return _index < _heap->num_regions(); 3037 } 3038 3039 char ShenandoahHeap::gc_state() const { 3040 return _gc_state.raw_value(); 3041 } 3042 3043 void ShenandoahHeap::deduplicate_string(oop str) { 3044 assert(java_lang_String::is_instance(str), "invariant"); 3045 3046 if (ShenandoahStringDedup::is_enabled()) { 3047 ShenandoahStringDedup::deduplicate(str); 3048 } 3049 } 3050 3051 const char* ShenandoahHeap::init_mark_event_message() const { 3052 assert(!has_forwarded_objects(), "Should not have forwarded objects here"); 3053 3054 bool proc_refs = process_references(); 3055 bool unload_cls = unload_classes(); 3056 3057 if (proc_refs && unload_cls) { 3058 return "Pause Init Mark (process weakrefs) (unload classes)"; 3059 } else if (proc_refs) { 3060 return "Pause Init Mark (process weakrefs)"; 3061 } else if (unload_cls) { 3062 return "Pause Init Mark (unload classes)"; 3063 } else { 3064 return "Pause Init Mark"; 3065 } 3066 } 3067 3068 const char* ShenandoahHeap::final_mark_event_message() const { 3069 assert(!has_forwarded_objects(), "Should not have forwarded objects here"); 3070 3071 bool proc_refs = process_references(); 3072 bool unload_cls = unload_classes(); 3073 3074 if (proc_refs && unload_cls) { 3075 return "Pause Final Mark (process weakrefs) (unload classes)"; 3076 } else if (proc_refs) { 3077 return "Pause Final Mark (process weakrefs)"; 3078 } else if (unload_cls) { 3079 return "Pause Final Mark (unload classes)"; 3080 } else { 3081 return "Pause Final Mark"; 3082 } 3083 } 3084 3085 const char* ShenandoahHeap::conc_mark_event_message() const { 3086 assert(!has_forwarded_objects(), "Should not have forwarded objects here"); 3087 3088 bool proc_refs = process_references(); 3089 bool unload_cls = unload_classes(); 3090 3091 if (proc_refs && unload_cls) { 3092 return "Concurrent marking (process weakrefs) (unload classes)"; 3093 } else if (proc_refs) { 3094 return "Concurrent marking (process weakrefs)"; 3095 } else if (unload_cls) { 3096 return "Concurrent marking (unload classes)"; 3097 } else { 3098 return "Concurrent marking"; 3099 } 3100 } 3101 3102 const char* ShenandoahHeap::degen_event_message(ShenandoahDegenPoint point) const { 3103 switch (point) { 3104 case _degenerated_unset: 3105 return "Pause Degenerated GC (<UNSET>)"; 3106 case _degenerated_outside_cycle: 3107 return "Pause Degenerated GC (Outside of Cycle)"; 3108 case _degenerated_mark: 3109 return "Pause Degenerated GC (Mark)"; 3110 case _degenerated_evac: 3111 return "Pause Degenerated GC (Evacuation)"; 3112 case _degenerated_updaterefs: 3113 return "Pause Degenerated GC (Update Refs)"; 3114 default: 3115 ShouldNotReachHere(); 3116 return "ERROR"; 3117 } 3118 } 3119 3120 ShenandoahLiveData* ShenandoahHeap::get_liveness_cache(uint worker_id) { 3121 #ifdef ASSERT 3122 assert(_liveness_cache != NULL, "sanity"); 3123 assert(worker_id < _max_workers, "sanity"); 3124 for (uint i = 0; i < num_regions(); i++) { 3125 assert(_liveness_cache[worker_id][i] == 0, "liveness cache should be empty"); 3126 } 3127 #endif 3128 return _liveness_cache[worker_id]; 3129 } 3130 3131 void ShenandoahHeap::flush_liveness_cache(uint worker_id) { 3132 assert(worker_id < _max_workers, "sanity"); 3133 assert(_liveness_cache != NULL, "sanity"); 3134 ShenandoahLiveData* ld = _liveness_cache[worker_id]; 3135 for (uint i = 0; i < num_regions(); i++) { 3136 ShenandoahLiveData live = ld[i]; 3137 if (live > 0) { 3138 ShenandoahHeapRegion* r = get_region(i); 3139 r->increase_live_data_gc_words(live); 3140 ld[i] = 0; 3141 } 3142 } 3143 }