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