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::gc_threads_do(ThreadClosure* tcl) const { 1182 workers()->threads_do(tcl); 1183 if (_safepoint_workers != NULL) { 1184 _safepoint_workers->threads_do(tcl); 1185 } 1186 if (ShenandoahStringDedup::is_enabled()) { 1187 ShenandoahStringDedup::threads_do(tcl); 1188 } 1189 } 1190 1191 void ShenandoahHeap::print_tracing_info() const { 1192 LogTarget(Info, gc, stats) lt; 1193 if (lt.is_enabled()) { 1194 ResourceMark rm; 1195 LogStream ls(lt); 1196 1197 phase_timings()->print_global_on(&ls); 1198 1199 ls.cr(); 1200 ls.cr(); 1201 1202 shenandoah_policy()->print_gc_stats(&ls); 1203 1204 ls.cr(); 1205 ls.cr(); 1206 1207 if (ShenandoahPacing) { 1208 pacer()->print_on(&ls); 1209 } 1210 1211 ls.cr(); 1212 ls.cr(); 1213 } 1214 } 1215 1216 void ShenandoahHeap::verify(VerifyOption vo) { 1217 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) { 1218 if (ShenandoahVerify) { 1219 verifier()->verify_generic(vo); 1220 } else { 1221 // TODO: Consider allocating verification bitmaps on demand, 1222 // and turn this on unconditionally. 1223 } 1224 } 1225 } 1226 size_t ShenandoahHeap::tlab_capacity(Thread *thr) const { 1227 return _free_set->capacity(); 1228 } 1229 1230 class ObjectIterateScanRootClosure : public BasicOopIterateClosure { 1231 private: 1232 MarkBitMap* _bitmap; 1233 Stack<oop,mtGC>* _oop_stack; 1234 ShenandoahHeap* const _heap; 1235 ShenandoahMarkingContext* const _marking_context; 1236 1237 template <class T> 1238 void do_oop_work(T* p) { 1239 T o = RawAccess<>::oop_load(p); 1240 if (!CompressedOops::is_null(o)) { 1241 oop obj = CompressedOops::decode_not_null(o); 1242 if (_heap->is_concurrent_weak_root_in_progress() && !_marking_context->is_marked(obj)) { 1243 // There may be dead oops in weak roots in concurrent root phase, do not touch them. 1244 return; 1245 } 1246 obj = ShenandoahBarrierSet::resolve_forwarded_not_null(obj); 1247 1248 assert(oopDesc::is_oop(obj), "must be a valid oop"); 1249 if (!_bitmap->is_marked(obj)) { 1250 _bitmap->mark(obj); 1251 _oop_stack->push(obj); 1252 } 1253 } 1254 } 1255 public: 1256 ObjectIterateScanRootClosure(MarkBitMap* bitmap, Stack<oop,mtGC>* oop_stack) : 1257 _bitmap(bitmap), _oop_stack(oop_stack), _heap(ShenandoahHeap::heap()), 1258 _marking_context(_heap->marking_context()) {} 1259 void do_oop(oop* p) { do_oop_work(p); } 1260 void do_oop(narrowOop* p) { do_oop_work(p); } 1261 }; 1262 1263 /* 1264 * This is public API, used in preparation of object_iterate(). 1265 * Since we don't do linear scan of heap in object_iterate() (see comment below), we don't 1266 * need to make the heap parsable. For Shenandoah-internal linear heap scans that we can 1267 * control, we call SH::make_tlabs_parsable(). 1268 */ 1269 void ShenandoahHeap::ensure_parsability(bool retire_tlabs) { 1270 // No-op. 1271 } 1272 1273 /* 1274 * Iterates objects in the heap. This is public API, used for, e.g., heap dumping. 1275 * 1276 * We cannot safely iterate objects by doing a linear scan at random points in time. Linear 1277 * scanning needs to deal with dead objects, which may have dead Klass* pointers (e.g. 1278 * calling oopDesc::size() would crash) or dangling reference fields (crashes) etc. Linear 1279 * scanning therefore depends on having a valid marking bitmap to support it. However, we only 1280 * have a valid marking bitmap after successful marking. In particular, we *don't* have a valid 1281 * marking bitmap during marking, after aborted marking or during/after cleanup (when we just 1282 * wiped the bitmap in preparation for next marking). 1283 * 1284 * For all those reasons, we implement object iteration as a single marking traversal, reporting 1285 * objects as we mark+traverse through the heap, starting from GC roots. JVMTI IterateThroughHeap 1286 * is allowed to report dead objects, but is not required to do so. 1287 */ 1288 void ShenandoahHeap::object_iterate(ObjectClosure* cl) { 1289 assert(SafepointSynchronize::is_at_safepoint(), "safe iteration is only available during safepoints"); 1290 if (!_aux_bitmap_region_special && !os::commit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size(), false)) { 1291 log_warning(gc)("Could not commit native memory for auxiliary marking bitmap for heap iteration"); 1292 return; 1293 } 1294 1295 // Reset bitmap 1296 _aux_bit_map.clear(); 1297 1298 Stack<oop,mtGC> oop_stack; 1299 1300 ObjectIterateScanRootClosure oops(&_aux_bit_map, &oop_stack); 1301 1302 { 1303 // First, we process GC roots according to current GC cycle. 1304 // This populates the work stack with initial objects. 1305 // It is important to relinquish the associated locks before diving 1306 // into heap dumper. 1307 ShenandoahHeapIterationRootScanner rp; 1308 rp.roots_do(&oops); 1309 } 1310 1311 // Work through the oop stack to traverse heap. 1312 while (! oop_stack.is_empty()) { 1313 oop obj = oop_stack.pop(); 1314 assert(oopDesc::is_oop(obj), "must be a valid oop"); 1315 cl->do_object(obj); 1316 obj->oop_iterate(&oops); 1317 } 1318 1319 assert(oop_stack.is_empty(), "should be empty"); 1320 1321 if (!_aux_bitmap_region_special && !os::uncommit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size())) { 1322 log_warning(gc)("Could not uncommit native memory for auxiliary marking bitmap for heap iteration"); 1323 } 1324 } 1325 1326 // Keep alive an object that was loaded with AS_NO_KEEPALIVE. 1327 void ShenandoahHeap::keep_alive(oop obj) { 1328 if (is_concurrent_mark_in_progress()) { 1329 ShenandoahBarrierSet::barrier_set()->enqueue(obj); 1330 } 1331 } 1332 1333 void ShenandoahHeap::heap_region_iterate(ShenandoahHeapRegionClosure* blk) const { 1334 for (size_t i = 0; i < num_regions(); i++) { 1335 ShenandoahHeapRegion* current = get_region(i); 1336 blk->heap_region_do(current); 1337 } 1338 } 1339 1340 class ShenandoahParallelHeapRegionTask : public AbstractGangTask { 1341 private: 1342 ShenandoahHeap* const _heap; 1343 ShenandoahHeapRegionClosure* const _blk; 1344 1345 shenandoah_padding(0); 1346 volatile size_t _index; 1347 shenandoah_padding(1); 1348 1349 public: 1350 ShenandoahParallelHeapRegionTask(ShenandoahHeapRegionClosure* blk) : 1351 AbstractGangTask("Parallel Region Task"), 1352 _heap(ShenandoahHeap::heap()), _blk(blk), _index(0) {} 1353 1354 void work(uint worker_id) { 1355 ShenandoahParallelWorkerSession worker_session(worker_id); 1356 size_t stride = ShenandoahParallelRegionStride; 1357 1358 size_t max = _heap->num_regions(); 1359 while (_index < max) { 1360 size_t cur = Atomic::fetch_and_add(&_index, stride); 1361 size_t start = cur; 1362 size_t end = MIN2(cur + stride, max); 1363 if (start >= max) break; 1364 1365 for (size_t i = cur; i < end; i++) { 1366 ShenandoahHeapRegion* current = _heap->get_region(i); 1367 _blk->heap_region_do(current); 1368 } 1369 } 1370 } 1371 }; 1372 1373 void ShenandoahHeap::parallel_heap_region_iterate(ShenandoahHeapRegionClosure* blk) const { 1374 assert(blk->is_thread_safe(), "Only thread-safe closures here"); 1375 if (num_regions() > ShenandoahParallelRegionStride) { 1376 ShenandoahParallelHeapRegionTask task(blk); 1377 workers()->run_task(&task); 1378 } else { 1379 heap_region_iterate(blk); 1380 } 1381 } 1382 1383 class ShenandoahInitMarkUpdateRegionStateClosure : public ShenandoahHeapRegionClosure { 1384 private: 1385 ShenandoahMarkingContext* const _ctx; 1386 public: 1387 ShenandoahInitMarkUpdateRegionStateClosure() : _ctx(ShenandoahHeap::heap()->marking_context()) {} 1388 1389 void heap_region_do(ShenandoahHeapRegion* r) { 1390 assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->index()); 1391 if (r->is_active()) { 1392 // Check if region needs updating its TAMS. We have updated it already during concurrent 1393 // reset, so it is very likely we don't need to do another write here. 1394 if (_ctx->top_at_mark_start(r) != r->top()) { 1395 _ctx->capture_top_at_mark_start(r); 1396 } 1397 } else { 1398 assert(_ctx->top_at_mark_start(r) == r->top(), 1399 "Region " SIZE_FORMAT " should already have correct TAMS", r->index()); 1400 } 1401 } 1402 1403 bool is_thread_safe() { return true; } 1404 }; 1405 1406 void ShenandoahHeap::op_init_mark() { 1407 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should be at safepoint"); 1408 assert(Thread::current()->is_VM_thread(), "can only do this in VMThread"); 1409 1410 assert(marking_context()->is_bitmap_clear(), "need clear marking bitmap"); 1411 assert(!marking_context()->is_complete(), "should not be complete"); 1412 assert(!has_forwarded_objects(), "No forwarded objects on this path"); 1413 1414 if (ShenandoahVerify) { 1415 verifier()->verify_before_concmark(); 1416 } 1417 1418 if (VerifyBeforeGC) { 1419 Universe::verify(); 1420 } 1421 1422 set_concurrent_mark_in_progress(true); 1423 // We need to reset all TLABs because we'd lose marks on all objects allocated in them. 1424 { 1425 ShenandoahGCPhase phase(ShenandoahPhaseTimings::make_parsable); 1426 make_parsable(true); 1427 } 1428 1429 { 1430 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_region_states); 1431 ShenandoahInitMarkUpdateRegionStateClosure cl; 1432 parallel_heap_region_iterate(&cl); 1433 } 1434 1435 // Make above changes visible to worker threads 1436 OrderAccess::fence(); 1437 1438 concurrent_mark()->mark_roots(ShenandoahPhaseTimings::scan_roots); 1439 1440 if (UseTLAB) { 1441 ShenandoahGCPhase phase(ShenandoahPhaseTimings::resize_tlabs); 1442 resize_tlabs(); 1443 } 1444 1445 if (ShenandoahPacing) { 1446 pacer()->setup_for_mark(); 1447 } 1448 1449 // Arm nmethods for concurrent marking. When a nmethod is about to be executed, 1450 // we need to make sure that all its metadata are marked. alternative is to remark 1451 // thread roots at final mark pause, but it can be potential latency killer. 1452 if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) { 1453 ShenandoahCodeRoots::arm_nmethods(); 1454 } 1455 } 1456 1457 void ShenandoahHeap::op_mark() { 1458 concurrent_mark()->mark_from_roots(); 1459 } 1460 1461 class ShenandoahFinalMarkUpdateRegionStateClosure : public ShenandoahHeapRegionClosure { 1462 private: 1463 ShenandoahMarkingContext* const _ctx; 1464 ShenandoahHeapLock* const _lock; 1465 1466 public: 1467 ShenandoahFinalMarkUpdateRegionStateClosure() : 1468 _ctx(ShenandoahHeap::heap()->complete_marking_context()), _lock(ShenandoahHeap::heap()->lock()) {} 1469 1470 void heap_region_do(ShenandoahHeapRegion* r) { 1471 if (r->is_active()) { 1472 // All allocations past TAMS are implicitly live, adjust the region data. 1473 // Bitmaps/TAMS are swapped at this point, so we need to poll complete bitmap. 1474 HeapWord *tams = _ctx->top_at_mark_start(r); 1475 HeapWord *top = r->top(); 1476 if (top > tams) { 1477 r->increase_live_data_alloc_words(pointer_delta(top, tams)); 1478 } 1479 1480 // We are about to select the collection set, make sure it knows about 1481 // current pinning status. Also, this allows trashing more regions that 1482 // now have their pinning status dropped. 1483 if (r->is_pinned()) { 1484 if (r->pin_count() == 0) { 1485 ShenandoahHeapLocker locker(_lock); 1486 r->make_unpinned(); 1487 } 1488 } else { 1489 if (r->pin_count() > 0) { 1490 ShenandoahHeapLocker locker(_lock); 1491 r->make_pinned(); 1492 } 1493 } 1494 1495 // Remember limit for updating refs. It's guaranteed that we get no 1496 // from-space-refs written from here on. 1497 r->set_update_watermark_at_safepoint(r->top()); 1498 } else { 1499 assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->index()); 1500 assert(_ctx->top_at_mark_start(r) == r->top(), 1501 "Region " SIZE_FORMAT " should have correct TAMS", r->index()); 1502 } 1503 } 1504 1505 bool is_thread_safe() { return true; } 1506 }; 1507 1508 void ShenandoahHeap::op_final_mark() { 1509 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should be at safepoint"); 1510 assert(!has_forwarded_objects(), "No forwarded objects on this path"); 1511 1512 // It is critical that we 1513 // evacuate roots right after finishing marking, so that we don't 1514 // get unmarked objects in the roots. 1515 1516 if (!cancelled_gc()) { 1517 concurrent_mark()->finish_mark_from_roots(/* full_gc = */ false); 1518 1519 // Marking is completed, deactivate SATB barrier 1520 set_concurrent_mark_in_progress(false); 1521 mark_complete_marking_context(); 1522 1523 parallel_cleaning(false /* full gc*/); 1524 1525 if (ShenandoahVerify) { 1526 verifier()->verify_roots_no_forwarded(); 1527 } 1528 1529 { 1530 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_region_states); 1531 ShenandoahFinalMarkUpdateRegionStateClosure cl; 1532 parallel_heap_region_iterate(&cl); 1533 1534 assert_pinned_region_status(); 1535 } 1536 1537 // Retire the TLABs, which will force threads to reacquire their TLABs after the pause. 1538 // This is needed for two reasons. Strong one: new allocations would be with new freeset, 1539 // which would be outside the collection set, so no cset writes would happen there. 1540 // Weaker one: new allocations would happen past update watermark, and so less work would 1541 // be needed for reference updates (would update the large filler instead). 1542 { 1543 ShenandoahGCPhase phase(ShenandoahPhaseTimings::retire_tlabs); 1544 make_parsable(true); 1545 } 1546 1547 { 1548 ShenandoahGCPhase phase(ShenandoahPhaseTimings::choose_cset); 1549 ShenandoahHeapLocker locker(lock()); 1550 _collection_set->clear(); 1551 heuristics()->choose_collection_set(_collection_set); 1552 } 1553 1554 { 1555 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_rebuild_freeset); 1556 ShenandoahHeapLocker locker(lock()); 1557 _free_set->rebuild(); 1558 } 1559 1560 if (!is_degenerated_gc_in_progress()) { 1561 prepare_concurrent_roots(); 1562 prepare_concurrent_unloading(); 1563 } 1564 1565 // If collection set has candidates, start evacuation. 1566 // Otherwise, bypass the rest of the cycle. 1567 if (!collection_set()->is_empty()) { 1568 ShenandoahGCPhase init_evac(ShenandoahPhaseTimings::init_evac); 1569 1570 if (ShenandoahVerify) { 1571 verifier()->verify_before_evacuation(); 1572 } 1573 1574 set_evacuation_in_progress(true); 1575 // From here on, we need to update references. 1576 set_has_forwarded_objects(true); 1577 1578 if (!is_degenerated_gc_in_progress()) { 1579 if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) { 1580 ShenandoahCodeRoots::arm_nmethods(); 1581 } 1582 evacuate_and_update_roots(); 1583 } 1584 1585 if (ShenandoahPacing) { 1586 pacer()->setup_for_evac(); 1587 } 1588 1589 if (ShenandoahVerify) { 1590 // If OOM while evacuating/updating of roots, there is no guarantee of their consistencies 1591 if (!cancelled_gc()) { 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 } 1604 verifier()->verify_during_evacuation(); 1605 } 1606 } else { 1607 if (ShenandoahVerify) { 1608 verifier()->verify_after_concmark(); 1609 } 1610 1611 if (VerifyAfterGC) { 1612 Universe::verify(); 1613 } 1614 } 1615 1616 } else { 1617 // If this cycle was updating references, we need to keep the has_forwarded_objects 1618 // flag on, for subsequent phases to deal with it. 1619 concurrent_mark()->cancel(); 1620 set_concurrent_mark_in_progress(false); 1621 1622 if (process_references()) { 1623 // Abandon reference processing right away: pre-cleaning must have failed. 1624 ReferenceProcessor *rp = ref_processor(); 1625 rp->disable_discovery(); 1626 rp->abandon_partial_discovery(); 1627 rp->verify_no_references_recorded(); 1628 } 1629 } 1630 } 1631 1632 void ShenandoahHeap::op_conc_evac() { 1633 ShenandoahEvacuationTask task(this, _collection_set, true); 1634 workers()->run_task(&task); 1635 } 1636 1637 void ShenandoahHeap::op_stw_evac() { 1638 ShenandoahEvacuationTask task(this, _collection_set, false); 1639 workers()->run_task(&task); 1640 } 1641 1642 void ShenandoahHeap::op_updaterefs() { 1643 update_heap_references(true); 1644 } 1645 1646 void ShenandoahHeap::op_cleanup_early() { 1647 free_set()->recycle_trash(); 1648 } 1649 1650 void ShenandoahHeap::op_cleanup_complete() { 1651 free_set()->recycle_trash(); 1652 } 1653 1654 class ShenandoahConcurrentRootsEvacUpdateTask : public AbstractGangTask { 1655 private: 1656 ShenandoahVMRoots<true /*concurrent*/> _vm_roots; 1657 ShenandoahClassLoaderDataRoots<true /*concurrent*/, false /*single threaded*/> _cld_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, ShenandoahHeap::heap()->workers()->active_workers()) {} 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 1683 class ShenandoahEvacUpdateCleanupOopStorageRootsClosure : public BasicOopIterateClosure { 1684 private: 1685 ShenandoahHeap* const _heap; 1686 ShenandoahMarkingContext* const _mark_context; 1687 bool _evac_in_progress; 1688 Thread* const _thread; 1689 1690 public: 1691 ShenandoahEvacUpdateCleanupOopStorageRootsClosure(); 1692 void do_oop(oop* p); 1693 void do_oop(narrowOop* p); 1694 }; 1695 1696 ShenandoahEvacUpdateCleanupOopStorageRootsClosure::ShenandoahEvacUpdateCleanupOopStorageRootsClosure() : 1697 _heap(ShenandoahHeap::heap()), 1698 _mark_context(ShenandoahHeap::heap()->marking_context()), 1699 _evac_in_progress(ShenandoahHeap::heap()->is_evacuation_in_progress()), 1700 _thread(Thread::current()) { 1701 } 1702 1703 void ShenandoahEvacUpdateCleanupOopStorageRootsClosure::do_oop(oop* p) { 1704 const oop obj = RawAccess<>::oop_load(p); 1705 if (!CompressedOops::is_null(obj)) { 1706 if (!_mark_context->is_marked(obj)) { 1707 shenandoah_assert_correct(p, obj); 1708 Atomic::cmpxchg(p, obj, oop(NULL)); 1709 } else if (_evac_in_progress && _heap->in_collection_set(obj)) { 1710 oop resolved = ShenandoahBarrierSet::resolve_forwarded_not_null(obj); 1711 if (resolved == obj) { 1712 resolved = _heap->evacuate_object(obj, _thread); 1713 } 1714 Atomic::cmpxchg(p, obj, resolved); 1715 assert(_heap->cancelled_gc() || 1716 _mark_context->is_marked(resolved) && !_heap->in_collection_set(resolved), 1717 "Sanity"); 1718 } 1719 } 1720 } 1721 1722 void ShenandoahEvacUpdateCleanupOopStorageRootsClosure::do_oop(narrowOop* p) { 1723 ShouldNotReachHere(); 1724 } 1725 1726 class ShenandoahIsCLDAliveClosure : public CLDClosure { 1727 public: 1728 void do_cld(ClassLoaderData* cld) { 1729 cld->is_alive(); 1730 } 1731 }; 1732 1733 class ShenandoahIsNMethodAliveClosure: public NMethodClosure { 1734 public: 1735 void do_nmethod(nmethod* n) { 1736 n->is_unloading(); 1737 } 1738 }; 1739 1740 // This task not only evacuates/updates marked weak roots, but also "NULL" 1741 // dead weak roots. 1742 class ShenandoahConcurrentWeakRootsEvacUpdateTask : public AbstractGangTask { 1743 private: 1744 ShenandoahVMWeakRoots<true /*concurrent*/> _vm_roots; 1745 1746 // Roots related to concurrent class unloading 1747 ShenandoahClassLoaderDataRoots<true /* concurrent */, false /* single thread*/> 1748 _cld_roots; 1749 ShenandoahConcurrentNMethodIterator _nmethod_itr; 1750 ShenandoahConcurrentStringDedupRoots _dedup_roots; 1751 bool _concurrent_class_unloading; 1752 1753 public: 1754 ShenandoahConcurrentWeakRootsEvacUpdateTask(ShenandoahPhaseTimings::Phase phase) : 1755 AbstractGangTask("Shenandoah Concurrent Weak Root Task"), 1756 _vm_roots(phase), 1757 _cld_roots(phase, ShenandoahHeap::heap()->workers()->active_workers()), 1758 _nmethod_itr(ShenandoahCodeRoots::table()), 1759 _dedup_roots(phase), 1760 _concurrent_class_unloading(ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) { 1761 if (_concurrent_class_unloading) { 1762 MutexLocker mu(CodeCache_lock, Mutex::_no_safepoint_check_flag); 1763 _nmethod_itr.nmethods_do_begin(); 1764 } 1765 } 1766 1767 ~ShenandoahConcurrentWeakRootsEvacUpdateTask() { 1768 if (_concurrent_class_unloading) { 1769 MutexLocker mu(CodeCache_lock, Mutex::_no_safepoint_check_flag); 1770 _nmethod_itr.nmethods_do_end(); 1771 } 1772 // Notify runtime data structures of potentially dead oops 1773 _vm_roots.notify(); 1774 } 1775 1776 void work(uint worker_id) { 1777 ShenandoahConcurrentWorkerSession worker_session(worker_id); 1778 { 1779 ShenandoahEvacOOMScope oom; 1780 // jni_roots and weak_roots are OopStorage backed roots, concurrent iteration 1781 // may race against OopStorage::release() calls. 1782 ShenandoahEvacUpdateCleanupOopStorageRootsClosure cl; 1783 _vm_roots.oops_do(&cl, worker_id); 1784 1785 // String dedup weak roots 1786 ShenandoahForwardedIsAliveClosure is_alive; 1787 ShenandoahEvacuateUpdateRootsClosure<MO_RELEASE> keep_alive; 1788 _dedup_roots.oops_do(&is_alive, &keep_alive, worker_id); 1789 } 1790 1791 // If we are going to perform concurrent class unloading later on, we need to 1792 // cleanup the weak oops in CLD and determinate nmethod's unloading state, so that we 1793 // can cleanup immediate garbage sooner. 1794 if (_concurrent_class_unloading) { 1795 // Applies ShenandoahIsCLDAlive closure to CLDs, native barrier will either NULL the 1796 // CLD's holder or evacuate it. 1797 ShenandoahIsCLDAliveClosure is_cld_alive; 1798 _cld_roots.cld_do(&is_cld_alive, worker_id); 1799 1800 // Applies ShenandoahIsNMethodAliveClosure to registered nmethods. 1801 // The closure calls nmethod->is_unloading(). The is_unloading 1802 // state is cached, therefore, during concurrent class unloading phase, 1803 // we will not touch the metadata of unloading nmethods 1804 ShenandoahIsNMethodAliveClosure is_nmethod_alive; 1805 _nmethod_itr.nmethods_do(&is_nmethod_alive); 1806 } 1807 } 1808 }; 1809 1810 void ShenandoahHeap::op_weak_roots() { 1811 if (is_concurrent_weak_root_in_progress()) { 1812 // Concurrent weak root processing 1813 { 1814 ShenandoahTimingsTracker t(ShenandoahPhaseTimings::conc_weak_roots_work); 1815 ShenandoahGCWorkerPhase worker_phase(ShenandoahPhaseTimings::conc_weak_roots_work); 1816 ShenandoahConcurrentWeakRootsEvacUpdateTask task(ShenandoahPhaseTimings::conc_weak_roots_work); 1817 workers()->run_task(&task); 1818 if (!ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) { 1819 set_concurrent_weak_root_in_progress(false); 1820 } 1821 } 1822 1823 // Perform handshake to flush out dead oops 1824 { 1825 ShenandoahTimingsTracker t(ShenandoahPhaseTimings::conc_weak_roots_rendezvous); 1826 ShenandoahRendezvousClosure cl; 1827 Handshake::execute(&cl); 1828 } 1829 } 1830 } 1831 1832 void ShenandoahHeap::op_class_unloading() { 1833 assert (is_concurrent_weak_root_in_progress() && 1834 ShenandoahConcurrentRoots::should_do_concurrent_class_unloading(), 1835 "Checked by caller"); 1836 _unloader.unload(); 1837 set_concurrent_weak_root_in_progress(false); 1838 } 1839 1840 void ShenandoahHeap::op_strong_roots() { 1841 assert(is_concurrent_strong_root_in_progress(), "Checked by caller"); 1842 ShenandoahConcurrentRootsEvacUpdateTask task(ShenandoahPhaseTimings::conc_strong_roots); 1843 workers()->run_task(&task); 1844 set_concurrent_strong_root_in_progress(false); 1845 } 1846 1847 class ShenandoahResetUpdateRegionStateClosure : public ShenandoahHeapRegionClosure { 1848 private: 1849 ShenandoahMarkingContext* const _ctx; 1850 public: 1851 ShenandoahResetUpdateRegionStateClosure() : _ctx(ShenandoahHeap::heap()->marking_context()) {} 1852 1853 void heap_region_do(ShenandoahHeapRegion* r) { 1854 if (r->is_active()) { 1855 // Reset live data and set TAMS optimistically. We would recheck these under the pause 1856 // anyway to capture any updates that happened since now. 1857 r->clear_live_data(); 1858 _ctx->capture_top_at_mark_start(r); 1859 } 1860 } 1861 1862 bool is_thread_safe() { return true; } 1863 }; 1864 1865 void ShenandoahHeap::op_reset() { 1866 if (ShenandoahPacing) { 1867 pacer()->setup_for_reset(); 1868 } 1869 reset_mark_bitmap(); 1870 1871 ShenandoahResetUpdateRegionStateClosure cl; 1872 parallel_heap_region_iterate(&cl); 1873 } 1874 1875 void ShenandoahHeap::op_preclean() { 1876 if (ShenandoahPacing) { 1877 pacer()->setup_for_preclean(); 1878 } 1879 concurrent_mark()->preclean_weak_refs(); 1880 } 1881 1882 void ShenandoahHeap::op_full(GCCause::Cause cause) { 1883 ShenandoahMetricsSnapshot metrics; 1884 metrics.snap_before(); 1885 1886 full_gc()->do_it(cause); 1887 if (UseTLAB) { 1888 ShenandoahGCPhase phase(ShenandoahPhaseTimings::full_gc_resize_tlabs); 1889 resize_all_tlabs(); 1890 } 1891 1892 metrics.snap_after(); 1893 1894 if (metrics.is_good_progress()) { 1895 _progress_last_gc.set(); 1896 } else { 1897 // Nothing to do. Tell the allocation path that we have failed to make 1898 // progress, and it can finally fail. 1899 _progress_last_gc.unset(); 1900 } 1901 } 1902 1903 void ShenandoahHeap::op_degenerated(ShenandoahDegenPoint point) { 1904 // Degenerated GC is STW, but it can also fail. Current mechanics communicates 1905 // GC failure via cancelled_concgc() flag. So, if we detect the failure after 1906 // some phase, we have to upgrade the Degenerate GC to Full GC. 1907 1908 clear_cancelled_gc(); 1909 1910 ShenandoahMetricsSnapshot metrics; 1911 metrics.snap_before(); 1912 1913 switch (point) { 1914 // The cases below form the Duff's-like device: it describes the actual GC cycle, 1915 // but enters it at different points, depending on which concurrent phase had 1916 // degenerated. 1917 1918 case _degenerated_outside_cycle: 1919 // We have degenerated from outside the cycle, which means something is bad with 1920 // the heap, most probably heavy humongous fragmentation, or we are very low on free 1921 // space. It makes little sense to wait for Full GC to reclaim as much as it can, when 1922 // we can do the most aggressive degen cycle, which includes processing references and 1923 // class unloading, unless those features are explicitly disabled. 1924 // 1925 // Note that we can only do this for "outside-cycle" degens, otherwise we would risk 1926 // changing the cycle parameters mid-cycle during concurrent -> degenerated handover. 1927 set_process_references(heuristics()->can_process_references()); 1928 set_unload_classes(heuristics()->can_unload_classes()); 1929 1930 op_reset(); 1931 1932 op_init_mark(); 1933 if (cancelled_gc()) { 1934 op_degenerated_fail(); 1935 return; 1936 } 1937 1938 case _degenerated_mark: 1939 op_final_mark(); 1940 if (cancelled_gc()) { 1941 op_degenerated_fail(); 1942 return; 1943 } 1944 1945 if (!has_forwarded_objects() && ShenandoahConcurrentRoots::can_do_concurrent_class_unloading()) { 1946 // Disarm nmethods that armed for concurrent mark. On normal cycle, it would 1947 // be disarmed while conc-roots phase is running. 1948 // TODO: Call op_conc_roots() here instead 1949 ShenandoahCodeRoots::disarm_nmethods(); 1950 } 1951 1952 op_cleanup_early(); 1953 1954 case _degenerated_evac: 1955 // If heuristics thinks we should do the cycle, this flag would be set, 1956 // and we can do evacuation. Otherwise, it would be the shortcut cycle. 1957 if (is_evacuation_in_progress()) { 1958 1959 // Degeneration under oom-evac protocol might have left some objects in 1960 // collection set un-evacuated. Restart evacuation from the beginning to 1961 // capture all objects. For all the objects that are already evacuated, 1962 // it would be a simple check, which is supposed to be fast. This is also 1963 // safe to do even without degeneration, as CSet iterator is at beginning 1964 // in preparation for evacuation anyway. 1965 // 1966 // Before doing that, we need to make sure we never had any cset-pinned 1967 // regions. This may happen if allocation failure happened when evacuating 1968 // the about-to-be-pinned object, oom-evac protocol left the object in 1969 // the collection set, and then the pin reached the cset region. If we continue 1970 // the cycle here, we would trash the cset and alive objects in it. To avoid 1971 // it, we fail degeneration right away and slide into Full GC to recover. 1972 1973 { 1974 sync_pinned_region_status(); 1975 collection_set()->clear_current_index(); 1976 1977 ShenandoahHeapRegion* r; 1978 while ((r = collection_set()->next()) != NULL) { 1979 if (r->is_pinned()) { 1980 cancel_gc(GCCause::_shenandoah_upgrade_to_full_gc); 1981 op_degenerated_fail(); 1982 return; 1983 } 1984 } 1985 1986 collection_set()->clear_current_index(); 1987 } 1988 1989 op_stw_evac(); 1990 if (cancelled_gc()) { 1991 op_degenerated_fail(); 1992 return; 1993 } 1994 } 1995 1996 // If heuristics thinks we should do the cycle, this flag would be set, 1997 // and we need to do update-refs. Otherwise, it would be the shortcut cycle. 1998 if (has_forwarded_objects()) { 1999 op_init_updaterefs(); 2000 if (cancelled_gc()) { 2001 op_degenerated_fail(); 2002 return; 2003 } 2004 } 2005 2006 case _degenerated_updaterefs: 2007 if (has_forwarded_objects()) { 2008 op_final_updaterefs(); 2009 if (cancelled_gc()) { 2010 op_degenerated_fail(); 2011 return; 2012 } 2013 } 2014 2015 op_cleanup_complete(); 2016 break; 2017 2018 default: 2019 ShouldNotReachHere(); 2020 } 2021 2022 if (ShenandoahVerify) { 2023 verifier()->verify_after_degenerated(); 2024 } 2025 2026 if (VerifyAfterGC) { 2027 Universe::verify(); 2028 } 2029 2030 metrics.snap_after(); 2031 2032 // Check for futility and fail. There is no reason to do several back-to-back Degenerated cycles, 2033 // because that probably means the heap is overloaded and/or fragmented. 2034 if (!metrics.is_good_progress()) { 2035 _progress_last_gc.unset(); 2036 cancel_gc(GCCause::_shenandoah_upgrade_to_full_gc); 2037 op_degenerated_futile(); 2038 } else { 2039 _progress_last_gc.set(); 2040 } 2041 } 2042 2043 void ShenandoahHeap::op_degenerated_fail() { 2044 log_info(gc)("Cannot finish degeneration, upgrading to Full GC"); 2045 shenandoah_policy()->record_degenerated_upgrade_to_full(); 2046 op_full(GCCause::_shenandoah_upgrade_to_full_gc); 2047 } 2048 2049 void ShenandoahHeap::op_degenerated_futile() { 2050 shenandoah_policy()->record_degenerated_upgrade_to_full(); 2051 op_full(GCCause::_shenandoah_upgrade_to_full_gc); 2052 } 2053 2054 void ShenandoahHeap::force_satb_flush_all_threads() { 2055 if (!is_concurrent_mark_in_progress()) { 2056 // No need to flush SATBs 2057 return; 2058 } 2059 2060 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) { 2061 ShenandoahThreadLocalData::set_force_satb_flush(t, true); 2062 } 2063 // The threads are not "acquiring" their thread-local data, but it does not 2064 // hurt to "release" the updates here anyway. 2065 OrderAccess::fence(); 2066 } 2067 2068 void ShenandoahHeap::set_gc_state_all_threads(char state) { 2069 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) { 2070 ShenandoahThreadLocalData::set_gc_state(t, state); 2071 } 2072 } 2073 2074 void ShenandoahHeap::set_gc_state_mask(uint mask, bool value) { 2075 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should really be Shenandoah safepoint"); 2076 _gc_state.set_cond(mask, value); 2077 set_gc_state_all_threads(_gc_state.raw_value()); 2078 } 2079 2080 void ShenandoahHeap::set_concurrent_mark_in_progress(bool in_progress) { 2081 if (has_forwarded_objects()) { 2082 set_gc_state_mask(MARKING | UPDATEREFS, in_progress); 2083 } else { 2084 set_gc_state_mask(MARKING, in_progress); 2085 } 2086 ShenandoahBarrierSet::satb_mark_queue_set().set_active_all_threads(in_progress, !in_progress); 2087 } 2088 2089 void ShenandoahHeap::set_evacuation_in_progress(bool in_progress) { 2090 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Only call this at safepoint"); 2091 set_gc_state_mask(EVACUATION, in_progress); 2092 } 2093 2094 void ShenandoahHeap::set_concurrent_strong_root_in_progress(bool in_progress) { 2095 assert(ShenandoahConcurrentRoots::can_do_concurrent_roots(), "Why set the flag?"); 2096 if (in_progress) { 2097 _concurrent_strong_root_in_progress.set(); 2098 } else { 2099 _concurrent_strong_root_in_progress.unset(); 2100 } 2101 } 2102 2103 void ShenandoahHeap::set_concurrent_weak_root_in_progress(bool in_progress) { 2104 assert(ShenandoahConcurrentRoots::can_do_concurrent_roots(), "Why set the flag?"); 2105 if (in_progress) { 2106 _concurrent_weak_root_in_progress.set(); 2107 } else { 2108 _concurrent_weak_root_in_progress.unset(); 2109 } 2110 } 2111 2112 void ShenandoahHeap::ref_processing_init() { 2113 assert(_max_workers > 0, "Sanity"); 2114 2115 _ref_processor = 2116 new ReferenceProcessor(&_subject_to_discovery, // is_subject_to_discovery 2117 _ref_proc_mt_processing, // MT processing 2118 _max_workers, // Degree of MT processing 2119 _ref_proc_mt_discovery, // MT discovery 2120 _max_workers, // Degree of MT discovery 2121 false, // Reference discovery is not atomic 2122 NULL, // No closure, should be installed before use 2123 true); // Scale worker threads 2124 2125 shenandoah_assert_rp_isalive_not_installed(); 2126 } 2127 2128 GCTracer* ShenandoahHeap::tracer() { 2129 return shenandoah_policy()->tracer(); 2130 } 2131 2132 size_t ShenandoahHeap::tlab_used(Thread* thread) const { 2133 return _free_set->used(); 2134 } 2135 2136 bool ShenandoahHeap::try_cancel_gc() { 2137 while (true) { 2138 jbyte prev = _cancelled_gc.cmpxchg(CANCELLED, CANCELLABLE); 2139 if (prev == CANCELLABLE) return true; 2140 else if (prev == CANCELLED) return false; 2141 assert(ShenandoahSuspendibleWorkers, "should not get here when not using suspendible workers"); 2142 assert(prev == NOT_CANCELLED, "must be NOT_CANCELLED"); 2143 if (Thread::current()->is_Java_thread()) { 2144 // We need to provide a safepoint here, otherwise we might 2145 // spin forever if a SP is pending. 2146 ThreadBlockInVM sp(JavaThread::current()); 2147 SpinPause(); 2148 } 2149 } 2150 } 2151 2152 void ShenandoahHeap::cancel_gc(GCCause::Cause cause) { 2153 if (try_cancel_gc()) { 2154 FormatBuffer<> msg("Cancelling GC: %s", GCCause::to_string(cause)); 2155 log_info(gc)("%s", msg.buffer()); 2156 Events::log(Thread::current(), "%s", msg.buffer()); 2157 } 2158 } 2159 2160 uint ShenandoahHeap::max_workers() { 2161 return _max_workers; 2162 } 2163 2164 void ShenandoahHeap::stop() { 2165 // The shutdown sequence should be able to terminate when GC is running. 2166 2167 // Step 0. Notify policy to disable event recording. 2168 _shenandoah_policy->record_shutdown(); 2169 2170 // Step 1. Notify control thread that we are in shutdown. 2171 // Note that we cannot do that with stop(), because stop() is blocking and waits for the actual shutdown. 2172 // Doing stop() here would wait for the normal GC cycle to complete, never falling through to cancel below. 2173 control_thread()->prepare_for_graceful_shutdown(); 2174 2175 // Step 2. Notify GC workers that we are cancelling GC. 2176 cancel_gc(GCCause::_shenandoah_stop_vm); 2177 2178 // Step 3. Wait until GC worker exits normally. 2179 control_thread()->stop(); 2180 2181 // Step 4. Stop String Dedup thread if it is active 2182 if (ShenandoahStringDedup::is_enabled()) { 2183 ShenandoahStringDedup::stop(); 2184 } 2185 } 2186 2187 void ShenandoahHeap::stw_unload_classes(bool full_gc) { 2188 if (!unload_classes()) return; 2189 2190 // Unload classes and purge SystemDictionary. 2191 { 2192 ShenandoahGCPhase phase(full_gc ? 2193 ShenandoahPhaseTimings::full_gc_purge_class_unload : 2194 ShenandoahPhaseTimings::purge_class_unload); 2195 bool purged_class = SystemDictionary::do_unloading(gc_timer()); 2196 2197 ShenandoahIsAliveSelector is_alive; 2198 uint num_workers = _workers->active_workers(); 2199 ShenandoahClassUnloadingTask unlink_task(is_alive.is_alive_closure(), num_workers, purged_class); 2200 _workers->run_task(&unlink_task); 2201 } 2202 2203 { 2204 ShenandoahGCPhase phase(full_gc ? 2205 ShenandoahPhaseTimings::full_gc_purge_cldg : 2206 ShenandoahPhaseTimings::purge_cldg); 2207 ClassLoaderDataGraph::purge(); 2208 } 2209 // Resize and verify metaspace 2210 MetaspaceGC::compute_new_size(); 2211 MetaspaceUtils::verify_metrics(); 2212 } 2213 2214 // Weak roots are either pre-evacuated (final mark) or updated (final updaterefs), 2215 // so they should not have forwarded oops. 2216 // However, we do need to "null" dead oops in the roots, if can not be done 2217 // in concurrent cycles. 2218 void ShenandoahHeap::stw_process_weak_roots(bool full_gc) { 2219 ShenandoahGCPhase root_phase(full_gc ? 2220 ShenandoahPhaseTimings::full_gc_purge : 2221 ShenandoahPhaseTimings::purge); 2222 uint num_workers = _workers->active_workers(); 2223 ShenandoahPhaseTimings::Phase timing_phase = full_gc ? 2224 ShenandoahPhaseTimings::full_gc_purge_weak_par : 2225 ShenandoahPhaseTimings::purge_weak_par; 2226 ShenandoahGCPhase phase(timing_phase); 2227 ShenandoahGCWorkerPhase worker_phase(timing_phase); 2228 2229 // Cleanup weak roots 2230 if (has_forwarded_objects()) { 2231 ShenandoahForwardedIsAliveClosure is_alive; 2232 ShenandoahUpdateRefsClosure keep_alive; 2233 ShenandoahParallelWeakRootsCleaningTask<ShenandoahForwardedIsAliveClosure, ShenandoahUpdateRefsClosure> 2234 cleaning_task(timing_phase, &is_alive, &keep_alive, num_workers, !ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()); 2235 _workers->run_task(&cleaning_task); 2236 } else { 2237 ShenandoahIsAliveClosure is_alive; 2238 #ifdef ASSERT 2239 ShenandoahAssertNotForwardedClosure verify_cl; 2240 ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, ShenandoahAssertNotForwardedClosure> 2241 cleaning_task(timing_phase, &is_alive, &verify_cl, num_workers, !ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()); 2242 #else 2243 ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, DoNothingClosure> 2244 cleaning_task(timing_phase, &is_alive, &do_nothing_cl, num_workers, !ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()); 2245 #endif 2246 _workers->run_task(&cleaning_task); 2247 } 2248 } 2249 2250 void ShenandoahHeap::parallel_cleaning(bool full_gc) { 2251 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint"); 2252 stw_process_weak_roots(full_gc); 2253 if (!ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) { 2254 stw_unload_classes(full_gc); 2255 } 2256 } 2257 2258 void ShenandoahHeap::set_has_forwarded_objects(bool cond) { 2259 set_gc_state_mask(HAS_FORWARDED, cond); 2260 } 2261 2262 void ShenandoahHeap::set_process_references(bool pr) { 2263 _process_references.set_cond(pr); 2264 } 2265 2266 void ShenandoahHeap::set_unload_classes(bool uc) { 2267 _unload_classes.set_cond(uc); 2268 } 2269 2270 bool ShenandoahHeap::process_references() const { 2271 return _process_references.is_set(); 2272 } 2273 2274 bool ShenandoahHeap::unload_classes() const { 2275 return _unload_classes.is_set(); 2276 } 2277 2278 address ShenandoahHeap::in_cset_fast_test_addr() { 2279 ShenandoahHeap* heap = ShenandoahHeap::heap(); 2280 assert(heap->collection_set() != NULL, "Sanity"); 2281 return (address) heap->collection_set()->biased_map_address(); 2282 } 2283 2284 address ShenandoahHeap::cancelled_gc_addr() { 2285 return (address) ShenandoahHeap::heap()->_cancelled_gc.addr_of(); 2286 } 2287 2288 address ShenandoahHeap::gc_state_addr() { 2289 return (address) ShenandoahHeap::heap()->_gc_state.addr_of(); 2290 } 2291 2292 size_t ShenandoahHeap::bytes_allocated_since_gc_start() { 2293 return Atomic::load_acquire(&_bytes_allocated_since_gc_start); 2294 } 2295 2296 void ShenandoahHeap::reset_bytes_allocated_since_gc_start() { 2297 Atomic::release_store_fence(&_bytes_allocated_since_gc_start, (size_t)0); 2298 } 2299 2300 void ShenandoahHeap::set_degenerated_gc_in_progress(bool in_progress) { 2301 _degenerated_gc_in_progress.set_cond(in_progress); 2302 } 2303 2304 void ShenandoahHeap::set_full_gc_in_progress(bool in_progress) { 2305 _full_gc_in_progress.set_cond(in_progress); 2306 } 2307 2308 void ShenandoahHeap::set_full_gc_move_in_progress(bool in_progress) { 2309 assert (is_full_gc_in_progress(), "should be"); 2310 _full_gc_move_in_progress.set_cond(in_progress); 2311 } 2312 2313 void ShenandoahHeap::set_update_refs_in_progress(bool in_progress) { 2314 set_gc_state_mask(UPDATEREFS, in_progress); 2315 } 2316 2317 void ShenandoahHeap::register_nmethod(nmethod* nm) { 2318 ShenandoahCodeRoots::register_nmethod(nm); 2319 } 2320 2321 void ShenandoahHeap::unregister_nmethod(nmethod* nm) { 2322 ShenandoahCodeRoots::unregister_nmethod(nm); 2323 } 2324 2325 void ShenandoahHeap::flush_nmethod(nmethod* nm) { 2326 ShenandoahCodeRoots::flush_nmethod(nm); 2327 } 2328 2329 oop ShenandoahHeap::pin_object(JavaThread* thr, oop o) { 2330 heap_region_containing(o)->record_pin(); 2331 return o; 2332 } 2333 2334 void ShenandoahHeap::unpin_object(JavaThread* thr, oop o) { 2335 heap_region_containing(o)->record_unpin(); 2336 } 2337 2338 void ShenandoahHeap::sync_pinned_region_status() { 2339 ShenandoahHeapLocker locker(lock()); 2340 2341 for (size_t i = 0; i < num_regions(); i++) { 2342 ShenandoahHeapRegion *r = get_region(i); 2343 if (r->is_active()) { 2344 if (r->is_pinned()) { 2345 if (r->pin_count() == 0) { 2346 r->make_unpinned(); 2347 } 2348 } else { 2349 if (r->pin_count() > 0) { 2350 r->make_pinned(); 2351 } 2352 } 2353 } 2354 } 2355 2356 assert_pinned_region_status(); 2357 } 2358 2359 #ifdef ASSERT 2360 void ShenandoahHeap::assert_pinned_region_status() { 2361 for (size_t i = 0; i < num_regions(); i++) { 2362 ShenandoahHeapRegion* r = get_region(i); 2363 assert((r->is_pinned() && r->pin_count() > 0) || (!r->is_pinned() && r->pin_count() == 0), 2364 "Region " SIZE_FORMAT " pinning status is inconsistent", i); 2365 } 2366 } 2367 #endif 2368 2369 ConcurrentGCTimer* ShenandoahHeap::gc_timer() const { 2370 return _gc_timer; 2371 } 2372 2373 void ShenandoahHeap::prepare_concurrent_roots() { 2374 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint"); 2375 if (ShenandoahConcurrentRoots::should_do_concurrent_roots()) { 2376 set_concurrent_strong_root_in_progress(!collection_set()->is_empty()); 2377 set_concurrent_weak_root_in_progress(true); 2378 } 2379 } 2380 2381 void ShenandoahHeap::prepare_concurrent_unloading() { 2382 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint"); 2383 if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) { 2384 _unloader.prepare(); 2385 } 2386 } 2387 2388 void ShenandoahHeap::finish_concurrent_unloading() { 2389 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint"); 2390 if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) { 2391 _unloader.finish(); 2392 } 2393 } 2394 2395 #ifdef ASSERT 2396 void ShenandoahHeap::assert_gc_workers(uint nworkers) { 2397 assert(nworkers > 0 && nworkers <= max_workers(), "Sanity"); 2398 2399 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) { 2400 if (UseDynamicNumberOfGCThreads) { 2401 assert(nworkers <= ParallelGCThreads, "Cannot use more than it has"); 2402 } else { 2403 // Use ParallelGCThreads inside safepoints 2404 assert(nworkers == ParallelGCThreads, "Use ParallelGCThreads within safepoints"); 2405 } 2406 } else { 2407 if (UseDynamicNumberOfGCThreads) { 2408 assert(nworkers <= ConcGCThreads, "Cannot use more than it has"); 2409 } else { 2410 // Use ConcGCThreads outside safepoints 2411 assert(nworkers == ConcGCThreads, "Use ConcGCThreads outside safepoints"); 2412 } 2413 } 2414 } 2415 #endif 2416 2417 ShenandoahVerifier* ShenandoahHeap::verifier() { 2418 guarantee(ShenandoahVerify, "Should be enabled"); 2419 assert (_verifier != NULL, "sanity"); 2420 return _verifier; 2421 } 2422 2423 template<class T> 2424 class ShenandoahUpdateHeapRefsTask : public AbstractGangTask { 2425 private: 2426 T cl; 2427 ShenandoahHeap* _heap; 2428 ShenandoahRegionIterator* _regions; 2429 bool _concurrent; 2430 public: 2431 ShenandoahUpdateHeapRefsTask(ShenandoahRegionIterator* regions, bool concurrent) : 2432 AbstractGangTask("Concurrent Update References Task"), 2433 cl(T()), 2434 _heap(ShenandoahHeap::heap()), 2435 _regions(regions), 2436 _concurrent(concurrent) { 2437 } 2438 2439 void work(uint worker_id) { 2440 if (_concurrent) { 2441 ShenandoahConcurrentWorkerSession worker_session(worker_id); 2442 ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers); 2443 do_work(); 2444 } else { 2445 ShenandoahParallelWorkerSession worker_session(worker_id); 2446 do_work(); 2447 } 2448 } 2449 2450 private: 2451 void do_work() { 2452 ShenandoahHeapRegion* r = _regions->next(); 2453 ShenandoahMarkingContext* const ctx = _heap->complete_marking_context(); 2454 while (r != NULL) { 2455 HeapWord* update_watermark = r->get_update_watermark(); 2456 assert (update_watermark >= r->bottom(), "sanity"); 2457 if (r->is_active() && !r->is_cset()) { 2458 _heap->marked_object_oop_iterate(r, &cl, update_watermark); 2459 } 2460 if (ShenandoahPacing) { 2461 _heap->pacer()->report_updaterefs(pointer_delta(update_watermark, r->bottom())); 2462 } 2463 if (_heap->check_cancelled_gc_and_yield(_concurrent)) { 2464 return; 2465 } 2466 r = _regions->next(); 2467 } 2468 } 2469 }; 2470 2471 void ShenandoahHeap::update_heap_references(bool concurrent) { 2472 ShenandoahUpdateHeapRefsTask<ShenandoahUpdateHeapRefsClosure> task(&_update_refs_iterator, concurrent); 2473 workers()->run_task(&task); 2474 } 2475 2476 void ShenandoahHeap::op_init_updaterefs() { 2477 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint"); 2478 2479 set_evacuation_in_progress(false); 2480 2481 { 2482 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_refs_retire_gclabs); 2483 retire_and_reset_gclabs(); 2484 } 2485 2486 if (ShenandoahVerify) { 2487 if (!is_degenerated_gc_in_progress()) { 2488 verifier()->verify_roots_in_to_space_except(ShenandoahRootVerifier::ThreadRoots); 2489 } 2490 verifier()->verify_before_updaterefs(); 2491 } 2492 2493 set_update_refs_in_progress(true); 2494 2495 _update_refs_iterator.reset(); 2496 2497 if (ShenandoahPacing) { 2498 pacer()->setup_for_updaterefs(); 2499 } 2500 } 2501 2502 class ShenandoahFinalUpdateRefsUpdateRegionStateClosure : public ShenandoahHeapRegionClosure { 2503 private: 2504 ShenandoahHeapLock* const _lock; 2505 2506 public: 2507 ShenandoahFinalUpdateRefsUpdateRegionStateClosure() : _lock(ShenandoahHeap::heap()->lock()) {} 2508 2509 void heap_region_do(ShenandoahHeapRegion* r) { 2510 // Drop unnecessary "pinned" state from regions that does not have CP marks 2511 // anymore, as this would allow trashing them. 2512 2513 if (r->is_active()) { 2514 if (r->is_pinned()) { 2515 if (r->pin_count() == 0) { 2516 ShenandoahHeapLocker locker(_lock); 2517 r->make_unpinned(); 2518 } 2519 } else { 2520 if (r->pin_count() > 0) { 2521 ShenandoahHeapLocker locker(_lock); 2522 r->make_pinned(); 2523 } 2524 } 2525 } 2526 } 2527 2528 bool is_thread_safe() { return true; } 2529 }; 2530 2531 void ShenandoahHeap::op_final_updaterefs() { 2532 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint"); 2533 2534 finish_concurrent_unloading(); 2535 2536 // Check if there is left-over work, and finish it 2537 if (_update_refs_iterator.has_next()) { 2538 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_finish_work); 2539 2540 // Finish updating references where we left off. 2541 clear_cancelled_gc(); 2542 update_heap_references(false); 2543 } 2544 2545 // Clear cancelled GC, if set. On cancellation path, the block before would handle 2546 // everything. On degenerated paths, cancelled gc would not be set anyway. 2547 if (cancelled_gc()) { 2548 clear_cancelled_gc(); 2549 } 2550 assert(!cancelled_gc(), "Should have been done right before"); 2551 2552 if (ShenandoahVerify && !is_degenerated_gc_in_progress()) { 2553 verifier()->verify_roots_in_to_space_except(ShenandoahRootVerifier::ThreadRoots); 2554 } 2555 2556 if (is_degenerated_gc_in_progress()) { 2557 concurrent_mark()->update_roots(ShenandoahPhaseTimings::degen_gc_update_roots); 2558 } else { 2559 concurrent_mark()->update_thread_roots(ShenandoahPhaseTimings::final_update_refs_roots); 2560 } 2561 2562 // Has to be done before cset is clear 2563 if (ShenandoahVerify) { 2564 verifier()->verify_roots_in_to_space(); 2565 } 2566 2567 { 2568 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_update_region_states); 2569 ShenandoahFinalUpdateRefsUpdateRegionStateClosure cl; 2570 parallel_heap_region_iterate(&cl); 2571 2572 assert_pinned_region_status(); 2573 } 2574 2575 { 2576 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_trash_cset); 2577 trash_cset_regions(); 2578 } 2579 2580 set_has_forwarded_objects(false); 2581 set_update_refs_in_progress(false); 2582 2583 if (ShenandoahVerify) { 2584 verifier()->verify_after_updaterefs(); 2585 } 2586 2587 if (VerifyAfterGC) { 2588 Universe::verify(); 2589 } 2590 2591 { 2592 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_rebuild_freeset); 2593 ShenandoahHeapLocker locker(lock()); 2594 _free_set->rebuild(); 2595 } 2596 } 2597 2598 void ShenandoahHeap::print_extended_on(outputStream *st) const { 2599 print_on(st); 2600 print_heap_regions_on(st); 2601 } 2602 2603 bool ShenandoahHeap::is_bitmap_slice_committed(ShenandoahHeapRegion* r, bool skip_self) { 2604 size_t slice = r->index() / _bitmap_regions_per_slice; 2605 2606 size_t regions_from = _bitmap_regions_per_slice * slice; 2607 size_t regions_to = MIN2(num_regions(), _bitmap_regions_per_slice * (slice + 1)); 2608 for (size_t g = regions_from; g < regions_to; g++) { 2609 assert (g / _bitmap_regions_per_slice == slice, "same slice"); 2610 if (skip_self && g == r->index()) continue; 2611 if (get_region(g)->is_committed()) { 2612 return true; 2613 } 2614 } 2615 return false; 2616 } 2617 2618 bool ShenandoahHeap::commit_bitmap_slice(ShenandoahHeapRegion* r) { 2619 shenandoah_assert_heaplocked(); 2620 2621 // Bitmaps in special regions do not need commits 2622 if (_bitmap_region_special) { 2623 return true; 2624 } 2625 2626 if (is_bitmap_slice_committed(r, true)) { 2627 // Some other region from the group is already committed, meaning the bitmap 2628 // slice is already committed, we exit right away. 2629 return true; 2630 } 2631 2632 // Commit the bitmap slice: 2633 size_t slice = r->index() / _bitmap_regions_per_slice; 2634 size_t off = _bitmap_bytes_per_slice * slice; 2635 size_t len = _bitmap_bytes_per_slice; 2636 char* start = (char*) _bitmap_region.start() + off; 2637 2638 if (!os::commit_memory(start, len, false)) { 2639 return false; 2640 } 2641 2642 if (AlwaysPreTouch) { 2643 os::pretouch_memory(start, start + len, _pretouch_bitmap_page_size); 2644 } 2645 2646 return true; 2647 } 2648 2649 bool ShenandoahHeap::uncommit_bitmap_slice(ShenandoahHeapRegion *r) { 2650 shenandoah_assert_heaplocked(); 2651 2652 // Bitmaps in special regions do not need uncommits 2653 if (_bitmap_region_special) { 2654 return true; 2655 } 2656 2657 if (is_bitmap_slice_committed(r, true)) { 2658 // Some other region from the group is still committed, meaning the bitmap 2659 // slice is should stay committed, exit right away. 2660 return true; 2661 } 2662 2663 // Uncommit the bitmap slice: 2664 size_t slice = r->index() / _bitmap_regions_per_slice; 2665 size_t off = _bitmap_bytes_per_slice * slice; 2666 size_t len = _bitmap_bytes_per_slice; 2667 if (!os::uncommit_memory((char*)_bitmap_region.start() + off, len)) { 2668 return false; 2669 } 2670 return true; 2671 } 2672 2673 void ShenandoahHeap::safepoint_synchronize_begin() { 2674 if (ShenandoahSuspendibleWorkers || UseStringDeduplication) { 2675 SuspendibleThreadSet::synchronize(); 2676 } 2677 } 2678 2679 void ShenandoahHeap::safepoint_synchronize_end() { 2680 if (ShenandoahSuspendibleWorkers || UseStringDeduplication) { 2681 SuspendibleThreadSet::desynchronize(); 2682 } 2683 } 2684 2685 void ShenandoahHeap::vmop_entry_init_mark() { 2686 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters()); 2687 ShenandoahTimingsTracker timing(ShenandoahPhaseTimings::init_mark_gross); 2688 2689 try_inject_alloc_failure(); 2690 VM_ShenandoahInitMark op; 2691 VMThread::execute(&op); // jump to entry_init_mark() under safepoint 2692 } 2693 2694 void ShenandoahHeap::vmop_entry_final_mark() { 2695 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters()); 2696 ShenandoahTimingsTracker timing(ShenandoahPhaseTimings::final_mark_gross); 2697 2698 try_inject_alloc_failure(); 2699 VM_ShenandoahFinalMarkStartEvac op; 2700 VMThread::execute(&op); // jump to entry_final_mark under safepoint 2701 } 2702 2703 void ShenandoahHeap::vmop_entry_init_updaterefs() { 2704 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters()); 2705 ShenandoahTimingsTracker timing(ShenandoahPhaseTimings::init_update_refs_gross); 2706 2707 try_inject_alloc_failure(); 2708 VM_ShenandoahInitUpdateRefs op; 2709 VMThread::execute(&op); 2710 } 2711 2712 void ShenandoahHeap::vmop_entry_final_updaterefs() { 2713 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters()); 2714 ShenandoahTimingsTracker timing(ShenandoahPhaseTimings::final_update_refs_gross); 2715 2716 try_inject_alloc_failure(); 2717 VM_ShenandoahFinalUpdateRefs op; 2718 VMThread::execute(&op); 2719 } 2720 2721 void ShenandoahHeap::vmop_entry_full(GCCause::Cause cause) { 2722 TraceCollectorStats tcs(monitoring_support()->full_stw_collection_counters()); 2723 ShenandoahTimingsTracker timing(ShenandoahPhaseTimings::full_gc_gross); 2724 2725 try_inject_alloc_failure(); 2726 VM_ShenandoahFullGC op(cause); 2727 VMThread::execute(&op); 2728 } 2729 2730 void ShenandoahHeap::vmop_degenerated(ShenandoahDegenPoint point) { 2731 TraceCollectorStats tcs(monitoring_support()->full_stw_collection_counters()); 2732 ShenandoahTimingsTracker timing(ShenandoahPhaseTimings::degen_gc_gross); 2733 2734 VM_ShenandoahDegeneratedGC degenerated_gc((int)point); 2735 VMThread::execute(°enerated_gc); 2736 } 2737 2738 void ShenandoahHeap::entry_init_mark() { 2739 const char* msg = init_mark_event_message(); 2740 ShenandoahPausePhase gc_phase(msg, ShenandoahPhaseTimings::init_mark); 2741 EventMark em("%s", msg); 2742 2743 ShenandoahWorkerScope scope(workers(), 2744 ShenandoahWorkerPolicy::calc_workers_for_init_marking(), 2745 "init marking"); 2746 2747 op_init_mark(); 2748 } 2749 2750 void ShenandoahHeap::entry_final_mark() { 2751 const char* msg = final_mark_event_message(); 2752 ShenandoahPausePhase gc_phase(msg, ShenandoahPhaseTimings::final_mark); 2753 EventMark em("%s", msg); 2754 2755 ShenandoahWorkerScope scope(workers(), 2756 ShenandoahWorkerPolicy::calc_workers_for_final_marking(), 2757 "final marking"); 2758 2759 op_final_mark(); 2760 } 2761 2762 void ShenandoahHeap::entry_init_updaterefs() { 2763 static const char* msg = "Pause Init Update Refs"; 2764 ShenandoahPausePhase gc_phase(msg, ShenandoahPhaseTimings::init_update_refs); 2765 EventMark em("%s", msg); 2766 2767 // No workers used in this phase, no setup required 2768 2769 op_init_updaterefs(); 2770 } 2771 2772 void ShenandoahHeap::entry_final_updaterefs() { 2773 static const char* msg = "Pause Final Update Refs"; 2774 ShenandoahPausePhase gc_phase(msg, ShenandoahPhaseTimings::final_update_refs); 2775 EventMark em("%s", msg); 2776 2777 ShenandoahWorkerScope scope(workers(), 2778 ShenandoahWorkerPolicy::calc_workers_for_final_update_ref(), 2779 "final reference update"); 2780 2781 op_final_updaterefs(); 2782 } 2783 2784 void ShenandoahHeap::entry_full(GCCause::Cause cause) { 2785 static const char* msg = "Pause Full"; 2786 ShenandoahPausePhase gc_phase(msg, ShenandoahPhaseTimings::full_gc, true /* log_heap_usage */); 2787 EventMark em("%s", msg); 2788 2789 ShenandoahWorkerScope scope(workers(), 2790 ShenandoahWorkerPolicy::calc_workers_for_fullgc(), 2791 "full gc"); 2792 2793 op_full(cause); 2794 } 2795 2796 void ShenandoahHeap::entry_degenerated(int point) { 2797 ShenandoahDegenPoint dpoint = (ShenandoahDegenPoint)point; 2798 const char* msg = degen_event_message(dpoint); 2799 ShenandoahPausePhase gc_phase(msg, ShenandoahPhaseTimings::degen_gc, true /* log_heap_usage */); 2800 EventMark em("%s", msg); 2801 2802 ShenandoahWorkerScope scope(workers(), 2803 ShenandoahWorkerPolicy::calc_workers_for_stw_degenerated(), 2804 "stw degenerated gc"); 2805 2806 set_degenerated_gc_in_progress(true); 2807 op_degenerated(dpoint); 2808 set_degenerated_gc_in_progress(false); 2809 } 2810 2811 void ShenandoahHeap::entry_mark() { 2812 TraceCollectorStats tcs(monitoring_support()->concurrent_collection_counters()); 2813 2814 const char* msg = conc_mark_event_message(); 2815 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_mark); 2816 EventMark em("%s", msg); 2817 2818 ShenandoahWorkerScope scope(workers(), 2819 ShenandoahWorkerPolicy::calc_workers_for_conc_marking(), 2820 "concurrent marking"); 2821 2822 try_inject_alloc_failure(); 2823 op_mark(); 2824 } 2825 2826 void ShenandoahHeap::entry_evac() { 2827 TraceCollectorStats tcs(monitoring_support()->concurrent_collection_counters()); 2828 2829 static const char* msg = "Concurrent evacuation"; 2830 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_evac); 2831 EventMark em("%s", msg); 2832 2833 ShenandoahWorkerScope scope(workers(), 2834 ShenandoahWorkerPolicy::calc_workers_for_conc_evac(), 2835 "concurrent evacuation"); 2836 2837 try_inject_alloc_failure(); 2838 op_conc_evac(); 2839 } 2840 2841 void ShenandoahHeap::entry_updaterefs() { 2842 static const char* msg = "Concurrent update references"; 2843 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_update_refs); 2844 EventMark em("%s", msg); 2845 2846 ShenandoahWorkerScope scope(workers(), 2847 ShenandoahWorkerPolicy::calc_workers_for_conc_update_ref(), 2848 "concurrent reference update"); 2849 2850 try_inject_alloc_failure(); 2851 op_updaterefs(); 2852 } 2853 2854 void ShenandoahHeap::entry_weak_roots() { 2855 static const char* msg = "Concurrent weak roots"; 2856 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_weak_roots); 2857 EventMark em("%s", msg); 2858 2859 ShenandoahWorkerScope scope(workers(), 2860 ShenandoahWorkerPolicy::calc_workers_for_conc_root_processing(), 2861 "concurrent weak root"); 2862 2863 try_inject_alloc_failure(); 2864 op_weak_roots(); 2865 } 2866 2867 void ShenandoahHeap::entry_class_unloading() { 2868 static const char* msg = "Concurrent class unloading"; 2869 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_class_unload); 2870 EventMark em("%s", msg); 2871 2872 ShenandoahWorkerScope scope(workers(), 2873 ShenandoahWorkerPolicy::calc_workers_for_conc_root_processing(), 2874 "concurrent class unloading"); 2875 2876 try_inject_alloc_failure(); 2877 op_class_unloading(); 2878 } 2879 2880 void ShenandoahHeap::entry_strong_roots() { 2881 static const char* msg = "Concurrent strong roots"; 2882 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_strong_roots); 2883 EventMark em("%s", msg); 2884 2885 ShenandoahGCWorkerPhase worker_phase(ShenandoahPhaseTimings::conc_strong_roots); 2886 2887 ShenandoahWorkerScope scope(workers(), 2888 ShenandoahWorkerPolicy::calc_workers_for_conc_root_processing(), 2889 "concurrent strong root"); 2890 2891 try_inject_alloc_failure(); 2892 op_strong_roots(); 2893 } 2894 2895 void ShenandoahHeap::entry_cleanup_early() { 2896 static const char* msg = "Concurrent cleanup"; 2897 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_cleanup_early, true /* log_heap_usage */); 2898 EventMark em("%s", msg); 2899 2900 // This phase does not use workers, no need for setup 2901 2902 try_inject_alloc_failure(); 2903 op_cleanup_early(); 2904 } 2905 2906 void ShenandoahHeap::entry_cleanup_complete() { 2907 static const char* msg = "Concurrent cleanup"; 2908 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_cleanup_complete, true /* log_heap_usage */); 2909 EventMark em("%s", msg); 2910 2911 // This phase does not use workers, no need for setup 2912 2913 try_inject_alloc_failure(); 2914 op_cleanup_complete(); 2915 } 2916 2917 void ShenandoahHeap::entry_reset() { 2918 static const char* msg = "Concurrent reset"; 2919 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_reset); 2920 EventMark em("%s", msg); 2921 2922 ShenandoahWorkerScope scope(workers(), 2923 ShenandoahWorkerPolicy::calc_workers_for_conc_reset(), 2924 "concurrent reset"); 2925 2926 try_inject_alloc_failure(); 2927 op_reset(); 2928 } 2929 2930 void ShenandoahHeap::entry_preclean() { 2931 if (ShenandoahPreclean && process_references()) { 2932 static const char* msg = "Concurrent precleaning"; 2933 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_preclean); 2934 EventMark em("%s", msg); 2935 2936 ShenandoahWorkerScope scope(workers(), 2937 ShenandoahWorkerPolicy::calc_workers_for_conc_preclean(), 2938 "concurrent preclean", 2939 /* check_workers = */ false); 2940 2941 try_inject_alloc_failure(); 2942 op_preclean(); 2943 } 2944 } 2945 2946 void ShenandoahHeap::entry_uncommit(double shrink_before) { 2947 static const char *msg = "Concurrent uncommit"; 2948 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_uncommit, true /* log_heap_usage */); 2949 EventMark em("%s", msg); 2950 2951 op_uncommit(shrink_before); 2952 } 2953 2954 void ShenandoahHeap::try_inject_alloc_failure() { 2955 if (ShenandoahAllocFailureALot && !cancelled_gc() && ((os::random() % 1000) > 950)) { 2956 _inject_alloc_failure.set(); 2957 os::naked_short_sleep(1); 2958 if (cancelled_gc()) { 2959 log_info(gc)("Allocation failure was successfully injected"); 2960 } 2961 } 2962 } 2963 2964 bool ShenandoahHeap::should_inject_alloc_failure() { 2965 return _inject_alloc_failure.is_set() && _inject_alloc_failure.try_unset(); 2966 } 2967 2968 void ShenandoahHeap::initialize_serviceability() { 2969 _memory_pool = new ShenandoahMemoryPool(this); 2970 _cycle_memory_manager.add_pool(_memory_pool); 2971 _stw_memory_manager.add_pool(_memory_pool); 2972 } 2973 2974 GrowableArray<GCMemoryManager*> ShenandoahHeap::memory_managers() { 2975 GrowableArray<GCMemoryManager*> memory_managers(2); 2976 memory_managers.append(&_cycle_memory_manager); 2977 memory_managers.append(&_stw_memory_manager); 2978 return memory_managers; 2979 } 2980 2981 GrowableArray<MemoryPool*> ShenandoahHeap::memory_pools() { 2982 GrowableArray<MemoryPool*> memory_pools(1); 2983 memory_pools.append(_memory_pool); 2984 return memory_pools; 2985 } 2986 2987 MemoryUsage ShenandoahHeap::memory_usage() { 2988 return _memory_pool->get_memory_usage(); 2989 } 2990 2991 ShenandoahRegionIterator::ShenandoahRegionIterator() : 2992 _heap(ShenandoahHeap::heap()), 2993 _index(0) {} 2994 2995 ShenandoahRegionIterator::ShenandoahRegionIterator(ShenandoahHeap* heap) : 2996 _heap(heap), 2997 _index(0) {} 2998 2999 void ShenandoahRegionIterator::reset() { 3000 _index = 0; 3001 } 3002 3003 bool ShenandoahRegionIterator::has_next() const { 3004 return _index < _heap->num_regions(); 3005 } 3006 3007 char ShenandoahHeap::gc_state() const { 3008 return _gc_state.raw_value(); 3009 } 3010 3011 void ShenandoahHeap::deduplicate_string(oop str) { 3012 assert(java_lang_String::is_instance(str), "invariant"); 3013 3014 if (ShenandoahStringDedup::is_enabled()) { 3015 ShenandoahStringDedup::deduplicate(str); 3016 } 3017 } 3018 3019 const char* ShenandoahHeap::init_mark_event_message() const { 3020 assert(!has_forwarded_objects(), "Should not have forwarded objects here"); 3021 3022 bool proc_refs = process_references(); 3023 bool unload_cls = unload_classes(); 3024 3025 if (proc_refs && unload_cls) { 3026 return "Pause Init Mark (process weakrefs) (unload classes)"; 3027 } else if (proc_refs) { 3028 return "Pause Init Mark (process weakrefs)"; 3029 } else if (unload_cls) { 3030 return "Pause Init Mark (unload classes)"; 3031 } else { 3032 return "Pause Init Mark"; 3033 } 3034 } 3035 3036 const char* ShenandoahHeap::final_mark_event_message() const { 3037 assert(!has_forwarded_objects(), "Should not have forwarded objects here"); 3038 3039 bool proc_refs = process_references(); 3040 bool unload_cls = unload_classes(); 3041 3042 if (proc_refs && unload_cls) { 3043 return "Pause Final Mark (process weakrefs) (unload classes)"; 3044 } else if (proc_refs) { 3045 return "Pause Final Mark (process weakrefs)"; 3046 } else if (unload_cls) { 3047 return "Pause Final Mark (unload classes)"; 3048 } else { 3049 return "Pause Final Mark"; 3050 } 3051 } 3052 3053 const char* ShenandoahHeap::conc_mark_event_message() const { 3054 assert(!has_forwarded_objects(), "Should not have forwarded objects here"); 3055 3056 bool proc_refs = process_references(); 3057 bool unload_cls = unload_classes(); 3058 3059 if (proc_refs && unload_cls) { 3060 return "Concurrent marking (process weakrefs) (unload classes)"; 3061 } else if (proc_refs) { 3062 return "Concurrent marking (process weakrefs)"; 3063 } else if (unload_cls) { 3064 return "Concurrent marking (unload classes)"; 3065 } else { 3066 return "Concurrent marking"; 3067 } 3068 } 3069 3070 const char* ShenandoahHeap::degen_event_message(ShenandoahDegenPoint point) const { 3071 switch (point) { 3072 case _degenerated_unset: 3073 return "Pause Degenerated GC (<UNSET>)"; 3074 case _degenerated_outside_cycle: 3075 return "Pause Degenerated GC (Outside of Cycle)"; 3076 case _degenerated_mark: 3077 return "Pause Degenerated GC (Mark)"; 3078 case _degenerated_evac: 3079 return "Pause Degenerated GC (Evacuation)"; 3080 case _degenerated_updaterefs: 3081 return "Pause Degenerated GC (Update Refs)"; 3082 default: 3083 ShouldNotReachHere(); 3084 return "ERROR"; 3085 } 3086 } 3087 3088 ShenandoahLiveData* ShenandoahHeap::get_liveness_cache(uint worker_id) { 3089 #ifdef ASSERT 3090 assert(_liveness_cache != NULL, "sanity"); 3091 assert(worker_id < _max_workers, "sanity"); 3092 for (uint i = 0; i < num_regions(); i++) { 3093 assert(_liveness_cache[worker_id][i] == 0, "liveness cache should be empty"); 3094 } 3095 #endif 3096 return _liveness_cache[worker_id]; 3097 } 3098 3099 void ShenandoahHeap::flush_liveness_cache(uint worker_id) { 3100 assert(worker_id < _max_workers, "sanity"); 3101 assert(_liveness_cache != NULL, "sanity"); 3102 ShenandoahLiveData* ld = _liveness_cache[worker_id]; 3103 for (uint i = 0; i < num_regions(); i++) { 3104 ShenandoahLiveData live = ld[i]; 3105 if (live > 0) { 3106 ShenandoahHeapRegion* r = get_region(i); 3107 r->increase_live_data_gc_words(live); 3108 ld[i] = 0; 3109 } 3110 } 3111 }