1 /* 2 * Copyright (c) 2013, 2019, Red Hat, Inc. All rights reserved. 3 * 4 * This code is free software; you can redistribute it and/or modify it 5 * under the terms of the GNU General Public License version 2 only, as 6 * published by the Free Software Foundation. 7 * 8 * This code is distributed in the hope that it will be useful, but WITHOUT 9 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 10 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 11 * version 2 for more details (a copy is included in the LICENSE file that 12 * accompanied this code). 13 * 14 * You should have received a copy of the GNU General Public License version 15 * 2 along with this work; if not, write to the Free Software Foundation, 16 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 17 * 18 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 19 * or visit www.oracle.com if you need additional information or have any 20 * questions. 21 * 22 */ 23 24 #include "precompiled.hpp" 25 #include "memory/allocation.hpp" 26 #include "memory/universe.hpp" 27 28 #include "gc/shared/gcArguments.hpp" 29 #include "gc/shared/gcTimer.hpp" 30 #include "gc/shared/gcTraceTime.inline.hpp" 31 #include "gc/shared/memAllocator.hpp" 32 #include "gc/shared/plab.hpp" 33 34 #include "gc/shenandoah/shenandoahAllocTracker.hpp" 35 #include "gc/shenandoah/shenandoahBarrierSet.hpp" 36 #include "gc/shenandoah/shenandoahClosures.inline.hpp" 37 #include "gc/shenandoah/shenandoahCollectionSet.hpp" 38 #include "gc/shenandoah/shenandoahCollectorPolicy.hpp" 39 #include "gc/shenandoah/shenandoahConcurrentMark.inline.hpp" 40 #include "gc/shenandoah/shenandoahConcurrentRoots.hpp" 41 #include "gc/shenandoah/shenandoahControlThread.hpp" 42 #include "gc/shenandoah/shenandoahFreeSet.hpp" 43 #include "gc/shenandoah/shenandoahPhaseTimings.hpp" 44 #include "gc/shenandoah/shenandoahHeap.inline.hpp" 45 #include "gc/shenandoah/shenandoahHeapRegion.hpp" 46 #include "gc/shenandoah/shenandoahHeapRegionSet.hpp" 47 #include "gc/shenandoah/shenandoahMarkCompact.hpp" 48 #include "gc/shenandoah/shenandoahMarkingContext.inline.hpp" 49 #include "gc/shenandoah/shenandoahMemoryPool.hpp" 50 #include "gc/shenandoah/shenandoahMetrics.hpp" 51 #include "gc/shenandoah/shenandoahMonitoringSupport.hpp" 52 #include "gc/shenandoah/shenandoahNormalMode.hpp" 53 #include "gc/shenandoah/shenandoahOopClosures.inline.hpp" 54 #include "gc/shenandoah/shenandoahPacer.inline.hpp" 55 #include "gc/shenandoah/shenandoahParallelCleaning.inline.hpp" 56 #include "gc/shenandoah/shenandoahPassiveMode.hpp" 57 #include "gc/shenandoah/shenandoahRootProcessor.inline.hpp" 58 #include "gc/shenandoah/shenandoahStringDedup.hpp" 59 #include "gc/shenandoah/shenandoahTaskqueue.hpp" 60 #include "gc/shenandoah/shenandoahTraversalMode.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 #if INCLUDE_JFR 68 #include "gc/shenandoah/shenandoahJfrSupport.hpp" 69 #endif 70 71 #include "memory/metaspace.hpp" 72 #include "oops/compressedOops.inline.hpp" 73 #include "runtime/globals.hpp" 74 #include "runtime/interfaceSupport.inline.hpp" 75 #include "runtime/safepointMechanism.hpp" 76 #include "runtime/vmThread.hpp" 77 #include "services/mallocTracker.hpp" 78 79 #ifdef ASSERT 80 template <class T> 81 void ShenandoahAssertToSpaceClosure::do_oop_work(T* p) { 82 T o = RawAccess<>::oop_load(p); 83 if (! CompressedOops::is_null(o)) { 84 oop obj = CompressedOops::decode_not_null(o); 85 shenandoah_assert_not_forwarded(p, obj); 86 } 87 } 88 89 void ShenandoahAssertToSpaceClosure::do_oop(narrowOop* p) { do_oop_work(p); } 90 void ShenandoahAssertToSpaceClosure::do_oop(oop* p) { do_oop_work(p); } 91 #endif 92 93 class ShenandoahPretouchHeapTask : public AbstractGangTask { 94 private: 95 ShenandoahRegionIterator _regions; 96 const size_t _page_size; 97 public: 98 ShenandoahPretouchHeapTask(size_t page_size) : 99 AbstractGangTask("Shenandoah Pretouch Heap"), 100 _page_size(page_size) {} 101 102 virtual void work(uint worker_id) { 103 ShenandoahHeapRegion* r = _regions.next(); 104 while (r != NULL) { 105 os::pretouch_memory(r->bottom(), r->end(), _page_size); 106 r = _regions.next(); 107 } 108 } 109 }; 110 111 class ShenandoahPretouchBitmapTask : public AbstractGangTask { 112 private: 113 ShenandoahRegionIterator _regions; 114 char* _bitmap_base; 115 const size_t _bitmap_size; 116 const size_t _page_size; 117 public: 118 ShenandoahPretouchBitmapTask(char* bitmap_base, size_t bitmap_size, size_t page_size) : 119 AbstractGangTask("Shenandoah Pretouch Bitmap"), 120 _bitmap_base(bitmap_base), 121 _bitmap_size(bitmap_size), 122 _page_size(page_size) {} 123 124 virtual void work(uint worker_id) { 125 ShenandoahHeapRegion* r = _regions.next(); 126 while (r != NULL) { 127 size_t start = r->region_number() * ShenandoahHeapRegion::region_size_bytes() / MarkBitMap::heap_map_factor(); 128 size_t end = (r->region_number() + 1) * ShenandoahHeapRegion::region_size_bytes() / MarkBitMap::heap_map_factor(); 129 assert (end <= _bitmap_size, "end is sane: " SIZE_FORMAT " < " SIZE_FORMAT, end, _bitmap_size); 130 131 os::pretouch_memory(_bitmap_base + start, _bitmap_base + end, _page_size); 132 133 r = _regions.next(); 134 } 135 } 136 }; 137 138 jint ShenandoahHeap::initialize() { 139 initialize_heuristics(); 140 141 // 142 // Figure out heap sizing 143 // 144 145 size_t init_byte_size = InitialHeapSize; 146 size_t min_byte_size = MinHeapSize; 147 size_t max_byte_size = MaxHeapSize; 148 size_t heap_alignment = HeapAlignment; 149 150 size_t reg_size_bytes = ShenandoahHeapRegion::region_size_bytes(); 151 152 if (ShenandoahAlwaysPreTouch) { 153 // Enabled pre-touch means the entire heap is committed right away. 154 init_byte_size = max_byte_size; 155 } 156 157 Universe::check_alignment(max_byte_size, reg_size_bytes, "Shenandoah heap"); 158 Universe::check_alignment(init_byte_size, reg_size_bytes, "Shenandoah heap"); 159 160 _num_regions = ShenandoahHeapRegion::region_count(); 161 162 size_t num_committed_regions = init_byte_size / reg_size_bytes; 163 num_committed_regions = MIN2(num_committed_regions, _num_regions); 164 assert(num_committed_regions <= _num_regions, "sanity"); 165 _initial_size = num_committed_regions * reg_size_bytes; 166 167 size_t num_min_regions = min_byte_size / reg_size_bytes; 168 num_min_regions = MIN2(num_min_regions, _num_regions); 169 assert(num_min_regions <= _num_regions, "sanity"); 170 _minimum_size = num_min_regions * reg_size_bytes; 171 172 _committed = _initial_size; 173 174 size_t heap_page_size = UseLargePages ? (size_t)os::large_page_size() : (size_t)os::vm_page_size(); 175 size_t bitmap_page_size = UseLargePages ? (size_t)os::large_page_size() : (size_t)os::vm_page_size(); 176 177 // 178 // Reserve and commit memory for heap 179 // 180 181 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size, heap_alignment); 182 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*) (heap_rs.base() + heap_rs.size())); 183 _heap_region = MemRegion((HeapWord*)heap_rs.base(), heap_rs.size() / HeapWordSize); 184 _heap_region_special = heap_rs.special(); 185 186 assert((((size_t) base()) & ShenandoahHeapRegion::region_size_bytes_mask()) == 0, 187 "Misaligned heap: " PTR_FORMAT, p2i(base())); 188 189 #if SHENANDOAH_OPTIMIZED_OBJTASK 190 // The optimized ObjArrayChunkedTask takes some bits away from the full object bits. 191 // Fail if we ever attempt to address more than we can. 192 if ((uintptr_t)heap_rs.end() >= ObjArrayChunkedTask::max_addressable()) { 193 FormatBuffer<512> buf("Shenandoah reserved [" PTR_FORMAT ", " PTR_FORMAT") for the heap, \n" 194 "but max object address is " PTR_FORMAT ". Try to reduce heap size, or try other \n" 195 "VM options that allocate heap at lower addresses (HeapBaseMinAddress, AllocateHeapAt, etc).", 196 p2i(heap_rs.base()), p2i(heap_rs.end()), ObjArrayChunkedTask::max_addressable()); 197 vm_exit_during_initialization("Fatal Error", buf); 198 } 199 #endif 200 201 ReservedSpace sh_rs = heap_rs.first_part(max_byte_size); 202 if (!_heap_region_special) { 203 os::commit_memory_or_exit(sh_rs.base(), _initial_size, heap_alignment, false, 204 "Cannot commit heap memory"); 205 } 206 207 // 208 // Reserve and commit memory for bitmap(s) 209 // 210 211 _bitmap_size = MarkBitMap::compute_size(heap_rs.size()); 212 _bitmap_size = align_up(_bitmap_size, bitmap_page_size); 213 214 size_t bitmap_bytes_per_region = reg_size_bytes / MarkBitMap::heap_map_factor(); 215 216 guarantee(bitmap_bytes_per_region != 0, 217 "Bitmap bytes per region should not be zero"); 218 guarantee(is_power_of_2(bitmap_bytes_per_region), 219 "Bitmap bytes per region should be power of two: " SIZE_FORMAT, bitmap_bytes_per_region); 220 221 if (bitmap_page_size > bitmap_bytes_per_region) { 222 _bitmap_regions_per_slice = bitmap_page_size / bitmap_bytes_per_region; 223 _bitmap_bytes_per_slice = bitmap_page_size; 224 } else { 225 _bitmap_regions_per_slice = 1; 226 _bitmap_bytes_per_slice = bitmap_bytes_per_region; 227 } 228 229 guarantee(_bitmap_regions_per_slice >= 1, 230 "Should have at least one region per slice: " SIZE_FORMAT, 231 _bitmap_regions_per_slice); 232 233 guarantee(((_bitmap_bytes_per_slice) % bitmap_page_size) == 0, 234 "Bitmap slices should be page-granular: bps = " SIZE_FORMAT ", page size = " SIZE_FORMAT, 235 _bitmap_bytes_per_slice, bitmap_page_size); 236 237 ReservedSpace bitmap(_bitmap_size, bitmap_page_size); 238 MemTracker::record_virtual_memory_type(bitmap.base(), mtGC); 239 _bitmap_region = MemRegion((HeapWord*) bitmap.base(), bitmap.size() / HeapWordSize); 240 _bitmap_region_special = bitmap.special(); 241 242 size_t bitmap_init_commit = _bitmap_bytes_per_slice * 243 align_up(num_committed_regions, _bitmap_regions_per_slice) / _bitmap_regions_per_slice; 244 bitmap_init_commit = MIN2(_bitmap_size, bitmap_init_commit); 245 if (!_bitmap_region_special) { 246 os::commit_memory_or_exit((char *) _bitmap_region.start(), bitmap_init_commit, bitmap_page_size, false, 247 "Cannot commit bitmap memory"); 248 } 249 250 _marking_context = new ShenandoahMarkingContext(_heap_region, _bitmap_region, _num_regions); 251 252 if (ShenandoahVerify) { 253 ReservedSpace verify_bitmap(_bitmap_size, bitmap_page_size); 254 if (!verify_bitmap.special()) { 255 os::commit_memory_or_exit(verify_bitmap.base(), verify_bitmap.size(), bitmap_page_size, false, 256 "Cannot commit verification bitmap memory"); 257 } 258 MemTracker::record_virtual_memory_type(verify_bitmap.base(), mtGC); 259 MemRegion verify_bitmap_region = MemRegion((HeapWord *) verify_bitmap.base(), verify_bitmap.size() / HeapWordSize); 260 _verification_bit_map.initialize(_heap_region, verify_bitmap_region); 261 _verifier = new ShenandoahVerifier(this, &_verification_bit_map); 262 } 263 264 // Reserve aux bitmap for use in object_iterate(). We don't commit it here. 265 ReservedSpace aux_bitmap(_bitmap_size, bitmap_page_size); 266 MemTracker::record_virtual_memory_type(aux_bitmap.base(), mtGC); 267 _aux_bitmap_region = MemRegion((HeapWord*) aux_bitmap.base(), aux_bitmap.size() / HeapWordSize); 268 _aux_bitmap_region_special = aux_bitmap.special(); 269 _aux_bit_map.initialize(_heap_region, _aux_bitmap_region); 270 271 // 272 // Create regions and region sets 273 // 274 275 _regions = NEW_C_HEAP_ARRAY(ShenandoahHeapRegion*, _num_regions, mtGC); 276 _free_set = new ShenandoahFreeSet(this, _num_regions); 277 _collection_set = new ShenandoahCollectionSet(this, sh_rs.base(), sh_rs.size()); 278 279 { 280 ShenandoahHeapLocker locker(lock()); 281 282 size_t size_words = ShenandoahHeapRegion::region_size_words(); 283 284 for (size_t i = 0; i < _num_regions; i++) { 285 HeapWord* start = (HeapWord*)sh_rs.base() + size_words * i; 286 bool is_committed = i < num_committed_regions; 287 ShenandoahHeapRegion* r = new ShenandoahHeapRegion(this, start, size_words, i, is_committed); 288 289 _marking_context->initialize_top_at_mark_start(r); 290 _regions[i] = r; 291 assert(!collection_set()->is_in(i), "New region should not be in collection set"); 292 } 293 294 // Initialize to complete 295 _marking_context->mark_complete(); 296 297 _free_set->rebuild(); 298 } 299 300 if (ShenandoahAlwaysPreTouch) { 301 assert(!AlwaysPreTouch, "Should have been overridden"); 302 303 // For NUMA, it is important to pre-touch the storage under bitmaps with worker threads, 304 // before initialize() below zeroes it with initializing thread. For any given region, 305 // we touch the region and the corresponding bitmaps from the same thread. 306 ShenandoahPushWorkerScope scope(workers(), _max_workers, false); 307 308 size_t pretouch_heap_page_size = heap_page_size; 309 size_t pretouch_bitmap_page_size = bitmap_page_size; 310 311 #ifdef LINUX 312 // UseTransparentHugePages would madvise that backing memory can be coalesced into huge 313 // pages. But, the kernel needs to know that every small page is used, in order to coalesce 314 // them into huge one. Therefore, we need to pretouch with smaller pages. 315 if (UseTransparentHugePages) { 316 pretouch_heap_page_size = (size_t)os::vm_page_size(); 317 pretouch_bitmap_page_size = (size_t)os::vm_page_size(); 318 } 319 #endif 320 321 // OS memory managers may want to coalesce back-to-back pages. Make their jobs 322 // simpler by pre-touching continuous spaces (heap and bitmap) separately. 323 324 log_info(gc, init)("Pretouch bitmap: " SIZE_FORMAT " regions, " SIZE_FORMAT " bytes page", 325 _num_regions, pretouch_bitmap_page_size); 326 ShenandoahPretouchBitmapTask bcl(bitmap.base(), _bitmap_size, pretouch_bitmap_page_size); 327 _workers->run_task(&bcl); 328 329 log_info(gc, init)("Pretouch heap: " SIZE_FORMAT " regions, " SIZE_FORMAT " bytes page", 330 _num_regions, pretouch_heap_page_size); 331 ShenandoahPretouchHeapTask hcl(pretouch_heap_page_size); 332 _workers->run_task(&hcl); 333 } 334 335 // 336 // Initialize the rest of GC subsystems 337 // 338 339 _liveness_cache = NEW_C_HEAP_ARRAY(jushort*, _max_workers, mtGC); 340 for (uint worker = 0; worker < _max_workers; worker++) { 341 _liveness_cache[worker] = NEW_C_HEAP_ARRAY(jushort, _num_regions, mtGC); 342 Copy::fill_to_bytes(_liveness_cache[worker], _num_regions * sizeof(jushort)); 343 } 344 345 // The call below uses stuff (the SATB* things) that are in G1, but probably 346 // belong into a shared location. 347 ShenandoahBarrierSet::satb_mark_queue_set().initialize(this, 348 20 /* G1SATBProcessCompletedThreshold */, 349 60 /* G1SATBBufferEnqueueingThresholdPercent */); 350 351 _monitoring_support = new ShenandoahMonitoringSupport(this); 352 _phase_timings = new ShenandoahPhaseTimings(); 353 ShenandoahStringDedup::initialize(); 354 ShenandoahCodeRoots::initialize(); 355 356 if (ShenandoahAllocationTrace) { 357 _alloc_tracker = new ShenandoahAllocTracker(); 358 } 359 360 if (ShenandoahPacing) { 361 _pacer = new ShenandoahPacer(this); 362 _pacer->setup_for_idle(); 363 } else { 364 _pacer = NULL; 365 } 366 367 _traversal_gc = strcmp(ShenandoahGCMode, "traversal") == 0 ? 368 new ShenandoahTraversalGC(this, _num_regions) : 369 NULL; 370 371 _control_thread = new ShenandoahControlThread(); 372 373 log_info(gc, init)("Initialize Shenandoah heap: " SIZE_FORMAT "%s initial, " SIZE_FORMAT "%s min, " SIZE_FORMAT "%s max", 374 byte_size_in_proper_unit(_initial_size), proper_unit_for_byte_size(_initial_size), 375 byte_size_in_proper_unit(_minimum_size), proper_unit_for_byte_size(_minimum_size), 376 byte_size_in_proper_unit(max_capacity()), proper_unit_for_byte_size(max_capacity()) 377 ); 378 379 log_info(gc, init)("Safepointing mechanism: %s", 380 SafepointMechanism::uses_thread_local_poll() ? "thread-local poll" : 381 (SafepointMechanism::uses_global_page_poll() ? "global-page poll" : "unknown")); 382 383 return JNI_OK; 384 } 385 386 void ShenandoahHeap::initialize_heuristics() { 387 if (ShenandoahGCMode != NULL) { 388 if (strcmp(ShenandoahGCMode, "traversal") == 0) { 389 _gc_mode = new ShenandoahTraversalMode(); 390 } else if (strcmp(ShenandoahGCMode, "normal") == 0) { 391 _gc_mode = new ShenandoahNormalMode(); 392 } else if (strcmp(ShenandoahGCMode, "passive") == 0) { 393 _gc_mode = new ShenandoahPassiveMode(); 394 } else { 395 vm_exit_during_initialization("Unknown -XX:ShenandoahGCMode option"); 396 } 397 } else { 398 ShouldNotReachHere(); 399 } 400 _gc_mode->initialize_flags(); 401 _heuristics = _gc_mode->initialize_heuristics(); 402 403 if (_heuristics->is_diagnostic() && !UnlockDiagnosticVMOptions) { 404 vm_exit_during_initialization( 405 err_msg("Heuristics \"%s\" is diagnostic, and must be enabled via -XX:+UnlockDiagnosticVMOptions.", 406 _heuristics->name())); 407 } 408 if (_heuristics->is_experimental() && !UnlockExperimentalVMOptions) { 409 vm_exit_during_initialization( 410 err_msg("Heuristics \"%s\" is experimental, and must be enabled via -XX:+UnlockExperimentalVMOptions.", 411 _heuristics->name())); 412 } 413 log_info(gc, init)("Shenandoah heuristics: %s", 414 _heuristics->name()); 415 } 416 417 #ifdef _MSC_VER 418 #pragma warning( push ) 419 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list 420 #endif 421 422 ShenandoahHeap::ShenandoahHeap(ShenandoahCollectorPolicy* policy) : 423 CollectedHeap(), 424 _initial_size(0), 425 _used(0), 426 _committed(0), 427 _bytes_allocated_since_gc_start(0), 428 _max_workers(MAX2(ConcGCThreads, ParallelGCThreads)), 429 _workers(NULL), 430 _safepoint_workers(NULL), 431 _heap_region_special(false), 432 _num_regions(0), 433 _regions(NULL), 434 _update_refs_iterator(this), 435 _control_thread(NULL), 436 _shenandoah_policy(policy), 437 _heuristics(NULL), 438 _free_set(NULL), 439 _scm(new ShenandoahConcurrentMark()), 440 _traversal_gc(NULL), 441 _full_gc(new ShenandoahMarkCompact()), 442 _pacer(NULL), 443 _verifier(NULL), 444 _alloc_tracker(NULL), 445 _phase_timings(NULL), 446 _monitoring_support(NULL), 447 _memory_pool(NULL), 448 _stw_memory_manager("Shenandoah Pauses", "end of GC pause"), 449 _cycle_memory_manager("Shenandoah Cycles", "end of GC cycle"), 450 _gc_timer(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()), 451 _soft_ref_policy(), 452 _log_min_obj_alignment_in_bytes(LogMinObjAlignmentInBytes), 453 _ref_processor(NULL), 454 _marking_context(NULL), 455 _bitmap_size(0), 456 _bitmap_regions_per_slice(0), 457 _bitmap_bytes_per_slice(0), 458 _bitmap_region_special(false), 459 _aux_bitmap_region_special(false), 460 _liveness_cache(NULL), 461 _collection_set(NULL) 462 { 463 log_info(gc, init)("GC threads: " UINT32_FORMAT " parallel, " UINT32_FORMAT " concurrent", ParallelGCThreads, ConcGCThreads); 464 log_info(gc, init)("Reference processing: %s", ParallelRefProcEnabled ? "parallel" : "serial"); 465 466 BarrierSet::set_barrier_set(new ShenandoahBarrierSet(this)); 467 468 _max_workers = MAX2(_max_workers, 1U); 469 _workers = new ShenandoahWorkGang("Shenandoah GC Threads", _max_workers, 470 /* are_GC_task_threads */ true, 471 /* are_ConcurrentGC_threads */ true); 472 if (_workers == NULL) { 473 vm_exit_during_initialization("Failed necessary allocation."); 474 } else { 475 _workers->initialize_workers(); 476 } 477 478 if (ShenandoahParallelSafepointThreads > 1) { 479 _safepoint_workers = new ShenandoahWorkGang("Safepoint Cleanup Thread", 480 ShenandoahParallelSafepointThreads, 481 /* are_GC_task_threads */ false, 482 /* are_ConcurrentGC_threads */ false); 483 _safepoint_workers->initialize_workers(); 484 } 485 } 486 487 #ifdef _MSC_VER 488 #pragma warning( pop ) 489 #endif 490 491 class ShenandoahResetBitmapTask : public AbstractGangTask { 492 private: 493 ShenandoahRegionIterator _regions; 494 495 public: 496 ShenandoahResetBitmapTask() : 497 AbstractGangTask("Parallel Reset Bitmap Task") {} 498 499 void work(uint worker_id) { 500 ShenandoahHeapRegion* region = _regions.next(); 501 ShenandoahHeap* heap = ShenandoahHeap::heap(); 502 ShenandoahMarkingContext* const ctx = heap->marking_context(); 503 while (region != NULL) { 504 if (heap->is_bitmap_slice_committed(region)) { 505 ctx->clear_bitmap(region); 506 } 507 region = _regions.next(); 508 } 509 } 510 }; 511 512 void ShenandoahHeap::reset_mark_bitmap() { 513 assert_gc_workers(_workers->active_workers()); 514 mark_incomplete_marking_context(); 515 516 ShenandoahResetBitmapTask task; 517 _workers->run_task(&task); 518 } 519 520 void ShenandoahHeap::print_on(outputStream* st) const { 521 st->print_cr("Shenandoah Heap"); 522 st->print_cr(" " SIZE_FORMAT "K total, " SIZE_FORMAT "K committed, " SIZE_FORMAT "K used", 523 max_capacity() / K, committed() / K, used() / K); 524 st->print_cr(" " SIZE_FORMAT " x " SIZE_FORMAT"K regions", 525 num_regions(), ShenandoahHeapRegion::region_size_bytes() / K); 526 527 st->print("Status: "); 528 if (has_forwarded_objects()) st->print("has forwarded objects, "); 529 if (is_concurrent_mark_in_progress()) st->print("marking, "); 530 if (is_evacuation_in_progress()) st->print("evacuating, "); 531 if (is_update_refs_in_progress()) st->print("updating refs, "); 532 if (is_concurrent_traversal_in_progress()) st->print("traversal, "); 533 if (is_degenerated_gc_in_progress()) st->print("degenerated gc, "); 534 if (is_full_gc_in_progress()) st->print("full gc, "); 535 if (is_full_gc_move_in_progress()) st->print("full gc move, "); 536 537 if (cancelled_gc()) { 538 st->print("cancelled"); 539 } else { 540 st->print("not cancelled"); 541 } 542 st->cr(); 543 544 st->print_cr("Reserved region:"); 545 st->print_cr(" - [" PTR_FORMAT ", " PTR_FORMAT ") ", 546 p2i(reserved_region().start()), 547 p2i(reserved_region().end())); 548 549 ShenandoahCollectionSet* cset = collection_set(); 550 st->print_cr("Collection set:"); 551 if (cset != NULL) { 552 st->print_cr(" - map (vanilla): " PTR_FORMAT, p2i(cset->map_address())); 553 st->print_cr(" - map (biased): " PTR_FORMAT, p2i(cset->biased_map_address())); 554 } else { 555 st->print_cr(" (NULL)"); 556 } 557 558 st->cr(); 559 MetaspaceUtils::print_on(st); 560 561 if (Verbose) { 562 print_heap_regions_on(st); 563 } 564 } 565 566 class ShenandoahInitWorkerGCLABClosure : public ThreadClosure { 567 public: 568 void do_thread(Thread* thread) { 569 assert(thread != NULL, "Sanity"); 570 assert(thread->is_Worker_thread(), "Only worker thread expected"); 571 ShenandoahThreadLocalData::initialize_gclab(thread); 572 } 573 }; 574 575 void ShenandoahHeap::post_initialize() { 576 CollectedHeap::post_initialize(); 577 MutexLocker ml(Threads_lock); 578 579 ShenandoahInitWorkerGCLABClosure init_gclabs; 580 _workers->threads_do(&init_gclabs); 581 582 // gclab can not be initialized early during VM startup, as it can not determinate its max_size. 583 // Now, we will let WorkGang to initialize gclab when new worker is created. 584 _workers->set_initialize_gclab(); 585 586 _scm->initialize(_max_workers); 587 _full_gc->initialize(_gc_timer); 588 589 ref_processing_init(); 590 591 _heuristics->initialize(); 592 593 JFR_ONLY(ShenandoahJFRSupport::register_jfr_type_serializers()); 594 } 595 596 size_t ShenandoahHeap::used() const { 597 return OrderAccess::load_acquire(&_used); 598 } 599 600 size_t ShenandoahHeap::committed() const { 601 OrderAccess::acquire(); 602 return _committed; 603 } 604 605 void ShenandoahHeap::increase_committed(size_t bytes) { 606 assert_heaplock_or_safepoint(); 607 _committed += bytes; 608 } 609 610 void ShenandoahHeap::decrease_committed(size_t bytes) { 611 assert_heaplock_or_safepoint(); 612 _committed -= bytes; 613 } 614 615 void ShenandoahHeap::increase_used(size_t bytes) { 616 Atomic::add(bytes, &_used); 617 } 618 619 void ShenandoahHeap::set_used(size_t bytes) { 620 OrderAccess::release_store_fence(&_used, bytes); 621 } 622 623 void ShenandoahHeap::decrease_used(size_t bytes) { 624 assert(used() >= bytes, "never decrease heap size by more than we've left"); 625 Atomic::sub(bytes, &_used); 626 } 627 628 void ShenandoahHeap::increase_allocated(size_t bytes) { 629 Atomic::add(bytes, &_bytes_allocated_since_gc_start); 630 } 631 632 void ShenandoahHeap::notify_mutator_alloc_words(size_t words, bool waste) { 633 size_t bytes = words * HeapWordSize; 634 if (!waste) { 635 increase_used(bytes); 636 } 637 increase_allocated(bytes); 638 if (ShenandoahPacing) { 639 control_thread()->pacing_notify_alloc(words); 640 if (waste) { 641 pacer()->claim_for_alloc(words, true); 642 } 643 } 644 } 645 646 size_t ShenandoahHeap::capacity() const { 647 return committed(); 648 } 649 650 size_t ShenandoahHeap::max_capacity() const { 651 return _num_regions * ShenandoahHeapRegion::region_size_bytes(); 652 } 653 654 size_t ShenandoahHeap::min_capacity() const { 655 return _minimum_size; 656 } 657 658 size_t ShenandoahHeap::initial_capacity() const { 659 return _initial_size; 660 } 661 662 bool ShenandoahHeap::is_in(const void* p) const { 663 HeapWord* heap_base = (HeapWord*) base(); 664 HeapWord* last_region_end = heap_base + ShenandoahHeapRegion::region_size_words() * num_regions(); 665 return p >= heap_base && p < last_region_end; 666 } 667 668 void ShenandoahHeap::op_uncommit(double shrink_before) { 669 assert (ShenandoahUncommit, "should be enabled"); 670 671 // Application allocates from the beginning of the heap, and GC allocates at 672 // the end of it. It is more efficient to uncommit from the end, so that applications 673 // could enjoy the near committed regions. GC allocations are much less frequent, 674 // and therefore can accept the committing costs. 675 676 size_t count = 0; 677 for (size_t i = num_regions(); i > 0; i--) { // care about size_t underflow 678 ShenandoahHeapRegion* r = get_region(i - 1); 679 if (r->is_empty_committed() && (r->empty_time() < shrink_before)) { 680 ShenandoahHeapLocker locker(lock()); 681 if (r->is_empty_committed()) { 682 // Do not uncommit below minimal capacity 683 if (committed() < min_capacity() + ShenandoahHeapRegion::region_size_bytes()) { 684 break; 685 } 686 687 r->make_uncommitted(); 688 count++; 689 } 690 } 691 SpinPause(); // allow allocators to take the lock 692 } 693 694 if (count > 0) { 695 control_thread()->notify_heap_changed(); 696 } 697 } 698 699 HeapWord* ShenandoahHeap::allocate_from_gclab_slow(Thread* thread, size_t size) { 700 // New object should fit the GCLAB size 701 size_t min_size = MAX2(size, PLAB::min_size()); 702 703 // Figure out size of new GCLAB, looking back at heuristics. Expand aggressively. 704 size_t new_size = ShenandoahThreadLocalData::gclab_size(thread) * 2; 705 new_size = MIN2(new_size, PLAB::max_size()); 706 new_size = MAX2(new_size, PLAB::min_size()); 707 708 // Record new heuristic value even if we take any shortcut. This captures 709 // the case when moderately-sized objects always take a shortcut. At some point, 710 // heuristics should catch up with them. 711 ShenandoahThreadLocalData::set_gclab_size(thread, new_size); 712 713 if (new_size < size) { 714 // New size still does not fit the object. Fall back to shared allocation. 715 // This avoids retiring perfectly good GCLABs, when we encounter a large object. 716 return NULL; 717 } 718 719 // Retire current GCLAB, and allocate a new one. 720 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread); 721 gclab->retire(); 722 723 size_t actual_size = 0; 724 HeapWord* gclab_buf = allocate_new_gclab(min_size, new_size, &actual_size); 725 if (gclab_buf == NULL) { 726 return NULL; 727 } 728 729 assert (size <= actual_size, "allocation should fit"); 730 731 if (ZeroTLAB) { 732 // ..and clear it. 733 Copy::zero_to_words(gclab_buf, actual_size); 734 } else { 735 // ...and zap just allocated object. 736 #ifdef ASSERT 737 // Skip mangling the space corresponding to the object header to 738 // ensure that the returned space is not considered parsable by 739 // any concurrent GC thread. 740 size_t hdr_size = oopDesc::header_size(); 741 Copy::fill_to_words(gclab_buf + hdr_size, actual_size - hdr_size, badHeapWordVal); 742 #endif // ASSERT 743 } 744 gclab->set_buf(gclab_buf, actual_size); 745 return gclab->allocate(size); 746 } 747 748 HeapWord* ShenandoahHeap::allocate_new_tlab(size_t min_size, 749 size_t requested_size, 750 size_t* actual_size) { 751 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_tlab(min_size, requested_size); 752 HeapWord* res = allocate_memory(req); 753 if (res != NULL) { 754 *actual_size = req.actual_size(); 755 } else { 756 *actual_size = 0; 757 } 758 return res; 759 } 760 761 HeapWord* ShenandoahHeap::allocate_new_gclab(size_t min_size, 762 size_t word_size, 763 size_t* actual_size) { 764 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_gclab(min_size, word_size); 765 HeapWord* res = allocate_memory(req); 766 if (res != NULL) { 767 *actual_size = req.actual_size(); 768 } else { 769 *actual_size = 0; 770 } 771 return res; 772 } 773 774 ShenandoahHeap* ShenandoahHeap::heap() { 775 CollectedHeap* heap = Universe::heap(); 776 assert(heap != NULL, "Unitialized access to ShenandoahHeap::heap()"); 777 assert(heap->kind() == CollectedHeap::Shenandoah, "not a shenandoah heap"); 778 return (ShenandoahHeap*) heap; 779 } 780 781 ShenandoahHeap* ShenandoahHeap::heap_no_check() { 782 CollectedHeap* heap = Universe::heap(); 783 return (ShenandoahHeap*) heap; 784 } 785 786 HeapWord* ShenandoahHeap::allocate_memory(ShenandoahAllocRequest& req) { 787 ShenandoahAllocTrace trace_alloc(req.size(), req.type()); 788 789 intptr_t pacer_epoch = 0; 790 bool in_new_region = false; 791 HeapWord* result = NULL; 792 793 if (req.is_mutator_alloc()) { 794 if (ShenandoahPacing) { 795 pacer()->pace_for_alloc(req.size()); 796 pacer_epoch = pacer()->epoch(); 797 } 798 799 if (!ShenandoahAllocFailureALot || !should_inject_alloc_failure()) { 800 result = allocate_memory_under_lock(req, in_new_region); 801 } 802 803 // Allocation failed, block until control thread reacted, then retry allocation. 804 // 805 // It might happen that one of the threads requesting allocation would unblock 806 // way later after GC happened, only to fail the second allocation, because 807 // other threads have already depleted the free storage. In this case, a better 808 // strategy is to try again, as long as GC makes progress. 809 // 810 // Then, we need to make sure the allocation was retried after at least one 811 // Full GC, which means we want to try more than ShenandoahFullGCThreshold times. 812 813 size_t tries = 0; 814 815 while (result == NULL && _progress_last_gc.is_set()) { 816 tries++; 817 control_thread()->handle_alloc_failure(req.size()); 818 result = allocate_memory_under_lock(req, in_new_region); 819 } 820 821 while (result == NULL && tries <= ShenandoahFullGCThreshold) { 822 tries++; 823 control_thread()->handle_alloc_failure(req.size()); 824 result = allocate_memory_under_lock(req, in_new_region); 825 } 826 827 } else { 828 assert(req.is_gc_alloc(), "Can only accept GC allocs here"); 829 result = allocate_memory_under_lock(req, in_new_region); 830 // Do not call handle_alloc_failure() here, because we cannot block. 831 // The allocation failure would be handled by the LRB slowpath with handle_alloc_failure_evac(). 832 } 833 834 if (in_new_region) { 835 control_thread()->notify_heap_changed(); 836 } 837 838 if (result != NULL) { 839 size_t requested = req.size(); 840 size_t actual = req.actual_size(); 841 842 assert (req.is_lab_alloc() || (requested == actual), 843 "Only LAB allocations are elastic: %s, requested = " SIZE_FORMAT ", actual = " SIZE_FORMAT, 844 ShenandoahAllocRequest::alloc_type_to_string(req.type()), requested, actual); 845 846 if (req.is_mutator_alloc()) { 847 notify_mutator_alloc_words(actual, false); 848 849 // If we requested more than we were granted, give the rest back to pacer. 850 // This only matters if we are in the same pacing epoch: do not try to unpace 851 // over the budget for the other phase. 852 if (ShenandoahPacing && (pacer_epoch > 0) && (requested > actual)) { 853 pacer()->unpace_for_alloc(pacer_epoch, requested - actual); 854 } 855 } else { 856 increase_used(actual*HeapWordSize); 857 } 858 } 859 860 return result; 861 } 862 863 HeapWord* ShenandoahHeap::allocate_memory_under_lock(ShenandoahAllocRequest& req, bool& in_new_region) { 864 ShenandoahHeapLocker locker(lock()); 865 return _free_set->allocate(req, in_new_region); 866 } 867 868 HeapWord* ShenandoahHeap::mem_allocate(size_t size, 869 bool* gc_overhead_limit_was_exceeded) { 870 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_shared(size); 871 return allocate_memory(req); 872 } 873 874 MetaWord* ShenandoahHeap::satisfy_failed_metadata_allocation(ClassLoaderData* loader_data, 875 size_t size, 876 Metaspace::MetadataType mdtype) { 877 MetaWord* result; 878 879 // Inform metaspace OOM to GC heuristics if class unloading is possible. 880 if (heuristics()->can_unload_classes()) { 881 ShenandoahHeuristics* h = heuristics(); 882 h->record_metaspace_oom(); 883 } 884 885 // Expand and retry allocation 886 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype); 887 if (result != NULL) { 888 return result; 889 } 890 891 // Start full GC 892 collect(GCCause::_metadata_GC_clear_soft_refs); 893 894 // Retry allocation 895 result = loader_data->metaspace_non_null()->allocate(size, mdtype); 896 if (result != NULL) { 897 return result; 898 } 899 900 // Expand and retry allocation 901 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype); 902 if (result != NULL) { 903 return result; 904 } 905 906 // Out of memory 907 return NULL; 908 } 909 910 class ShenandoahConcurrentEvacuateRegionObjectClosure : public ObjectClosure { 911 private: 912 ShenandoahHeap* const _heap; 913 Thread* const _thread; 914 public: 915 ShenandoahConcurrentEvacuateRegionObjectClosure(ShenandoahHeap* heap) : 916 _heap(heap), _thread(Thread::current()) {} 917 918 void do_object(oop p) { 919 shenandoah_assert_marked(NULL, p); 920 if (!p->is_forwarded()) { 921 _heap->evacuate_object(p, _thread); 922 } 923 } 924 }; 925 926 class ShenandoahEvacuationTask : public AbstractGangTask { 927 private: 928 ShenandoahHeap* const _sh; 929 ShenandoahCollectionSet* const _cs; 930 bool _concurrent; 931 public: 932 ShenandoahEvacuationTask(ShenandoahHeap* sh, 933 ShenandoahCollectionSet* cs, 934 bool concurrent) : 935 AbstractGangTask("Parallel Evacuation Task"), 936 _sh(sh), 937 _cs(cs), 938 _concurrent(concurrent) 939 {} 940 941 void work(uint worker_id) { 942 if (_concurrent) { 943 ShenandoahConcurrentWorkerSession worker_session(worker_id); 944 ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers); 945 ShenandoahEvacOOMScope oom_evac_scope; 946 do_work(); 947 } else { 948 ShenandoahParallelWorkerSession worker_session(worker_id); 949 ShenandoahEvacOOMScope oom_evac_scope; 950 do_work(); 951 } 952 } 953 954 private: 955 void do_work() { 956 ShenandoahConcurrentEvacuateRegionObjectClosure cl(_sh); 957 ShenandoahHeapRegion* r; 958 while ((r =_cs->claim_next()) != NULL) { 959 assert(r->has_live(), "all-garbage regions are reclaimed early"); 960 _sh->marked_object_iterate(r, &cl); 961 962 if (ShenandoahPacing) { 963 _sh->pacer()->report_evac(r->used() >> LogHeapWordSize); 964 } 965 966 if (_sh->check_cancelled_gc_and_yield(_concurrent)) { 967 break; 968 } 969 } 970 } 971 }; 972 973 void ShenandoahHeap::trash_cset_regions() { 974 ShenandoahHeapLocker locker(lock()); 975 976 ShenandoahCollectionSet* set = collection_set(); 977 ShenandoahHeapRegion* r; 978 set->clear_current_index(); 979 while ((r = set->next()) != NULL) { 980 r->make_trash(); 981 } 982 collection_set()->clear(); 983 } 984 985 void ShenandoahHeap::print_heap_regions_on(outputStream* st) const { 986 st->print_cr("Heap Regions:"); 987 st->print_cr("EU=empty-uncommitted, EC=empty-committed, R=regular, H=humongous start, HC=humongous continuation, CS=collection set, T=trash, P=pinned"); 988 st->print_cr("BTE=bottom/top/end, U=used, T=TLAB allocs, G=GCLAB allocs, S=shared allocs, L=live data"); 989 st->print_cr("R=root, CP=critical pins, TAMS=top-at-mark-start (previous, next)"); 990 st->print_cr("SN=alloc sequence numbers (first mutator, last mutator, first gc, last gc)"); 991 992 for (size_t i = 0; i < num_regions(); i++) { 993 get_region(i)->print_on(st); 994 } 995 } 996 997 void ShenandoahHeap::trash_humongous_region_at(ShenandoahHeapRegion* start) { 998 assert(start->is_humongous_start(), "reclaim regions starting with the first one"); 999 1000 oop humongous_obj = oop(start->bottom()); 1001 size_t size = humongous_obj->size(); 1002 size_t required_regions = ShenandoahHeapRegion::required_regions(size * HeapWordSize); 1003 size_t index = start->region_number() + required_regions - 1; 1004 1005 assert(!start->has_live(), "liveness must be zero"); 1006 1007 for(size_t i = 0; i < required_regions; i++) { 1008 // Reclaim from tail. Otherwise, assertion fails when printing region to trace log, 1009 // as it expects that every region belongs to a humongous region starting with a humongous start region. 1010 ShenandoahHeapRegion* region = get_region(index --); 1011 1012 assert(region->is_humongous(), "expect correct humongous start or continuation"); 1013 assert(!region->is_cset(), "Humongous region should not be in collection set"); 1014 1015 region->make_trash_immediate(); 1016 } 1017 } 1018 1019 class ShenandoahRetireGCLABClosure : public ThreadClosure { 1020 public: 1021 void do_thread(Thread* thread) { 1022 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread); 1023 assert(gclab != NULL, "GCLAB should be initialized for %s", thread->name()); 1024 gclab->retire(); 1025 } 1026 }; 1027 1028 void ShenandoahHeap::make_parsable(bool retire_tlabs) { 1029 if (UseTLAB) { 1030 CollectedHeap::ensure_parsability(retire_tlabs); 1031 } 1032 ShenandoahRetireGCLABClosure cl; 1033 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) { 1034 cl.do_thread(t); 1035 } 1036 workers()->threads_do(&cl); 1037 } 1038 1039 void ShenandoahHeap::resize_tlabs() { 1040 CollectedHeap::resize_all_tlabs(); 1041 } 1042 1043 class ShenandoahEvacuateUpdateRootsTask : public AbstractGangTask { 1044 private: 1045 ShenandoahRootEvacuator* _rp; 1046 1047 public: 1048 ShenandoahEvacuateUpdateRootsTask(ShenandoahRootEvacuator* rp) : 1049 AbstractGangTask("Shenandoah evacuate and update roots"), 1050 _rp(rp) {} 1051 1052 void work(uint worker_id) { 1053 ShenandoahParallelWorkerSession worker_session(worker_id); 1054 ShenandoahEvacOOMScope oom_evac_scope; 1055 ShenandoahEvacuateUpdateRootsClosure cl; 1056 MarkingCodeBlobClosure blobsCl(&cl, CodeBlobToOopClosure::FixRelocations); 1057 _rp->roots_do(worker_id, &cl); 1058 } 1059 }; 1060 1061 void ShenandoahHeap::evacuate_and_update_roots() { 1062 #if COMPILER2_OR_JVMCI 1063 DerivedPointerTable::clear(); 1064 #endif 1065 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Only iterate roots while world is stopped"); 1066 { 1067 // Include concurrent roots if current cycle can not process those roots concurrently 1068 ShenandoahRootEvacuator rp(workers()->active_workers(), 1069 ShenandoahPhaseTimings::init_evac, 1070 !ShenandoahConcurrentRoots::should_do_concurrent_roots()); 1071 ShenandoahEvacuateUpdateRootsTask roots_task(&rp); 1072 workers()->run_task(&roots_task); 1073 } 1074 1075 #if COMPILER2_OR_JVMCI 1076 DerivedPointerTable::update_pointers(); 1077 #endif 1078 } 1079 1080 // Returns size in bytes 1081 size_t ShenandoahHeap::unsafe_max_tlab_alloc(Thread *thread) const { 1082 if (ShenandoahElasticTLAB) { 1083 // With Elastic TLABs, return the max allowed size, and let the allocation path 1084 // figure out the safe size for current allocation. 1085 return ShenandoahHeapRegion::max_tlab_size_bytes(); 1086 } else { 1087 return MIN2(_free_set->unsafe_peek_free(), ShenandoahHeapRegion::max_tlab_size_bytes()); 1088 } 1089 } 1090 1091 size_t ShenandoahHeap::max_tlab_size() const { 1092 // Returns size in words 1093 return ShenandoahHeapRegion::max_tlab_size_words(); 1094 } 1095 1096 class ShenandoahRetireAndResetGCLABClosure : public ThreadClosure { 1097 public: 1098 void do_thread(Thread* thread) { 1099 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread); 1100 gclab->retire(); 1101 if (ShenandoahThreadLocalData::gclab_size(thread) > 0) { 1102 ShenandoahThreadLocalData::set_gclab_size(thread, 0); 1103 } 1104 } 1105 }; 1106 1107 void ShenandoahHeap::retire_and_reset_gclabs() { 1108 ShenandoahRetireAndResetGCLABClosure cl; 1109 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) { 1110 cl.do_thread(t); 1111 } 1112 workers()->threads_do(&cl); 1113 } 1114 1115 void ShenandoahHeap::collect(GCCause::Cause cause) { 1116 control_thread()->request_gc(cause); 1117 } 1118 1119 void ShenandoahHeap::do_full_collection(bool clear_all_soft_refs) { 1120 //assert(false, "Shouldn't need to do full collections"); 1121 } 1122 1123 HeapWord* ShenandoahHeap::block_start(const void* addr) const { 1124 Space* sp = heap_region_containing(addr); 1125 if (sp != NULL) { 1126 return sp->block_start(addr); 1127 } 1128 return NULL; 1129 } 1130 1131 bool ShenandoahHeap::block_is_obj(const HeapWord* addr) const { 1132 Space* sp = heap_region_containing(addr); 1133 return sp->block_is_obj(addr); 1134 } 1135 1136 jlong ShenandoahHeap::millis_since_last_gc() { 1137 double v = heuristics()->time_since_last_gc() * 1000; 1138 assert(0 <= v && v <= max_jlong, "value should fit: %f", v); 1139 return (jlong)v; 1140 } 1141 1142 void ShenandoahHeap::prepare_for_verify() { 1143 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) { 1144 make_parsable(false); 1145 } 1146 } 1147 1148 void ShenandoahHeap::print_gc_threads_on(outputStream* st) const { 1149 workers()->print_worker_threads_on(st); 1150 if (ShenandoahStringDedup::is_enabled()) { 1151 ShenandoahStringDedup::print_worker_threads_on(st); 1152 } 1153 } 1154 1155 void ShenandoahHeap::gc_threads_do(ThreadClosure* tcl) const { 1156 workers()->threads_do(tcl); 1157 if (_safepoint_workers != NULL) { 1158 _safepoint_workers->threads_do(tcl); 1159 } 1160 if (ShenandoahStringDedup::is_enabled()) { 1161 ShenandoahStringDedup::threads_do(tcl); 1162 } 1163 } 1164 1165 void ShenandoahHeap::print_tracing_info() const { 1166 LogTarget(Info, gc, stats) lt; 1167 if (lt.is_enabled()) { 1168 ResourceMark rm; 1169 LogStream ls(lt); 1170 1171 phase_timings()->print_on(&ls); 1172 1173 ls.cr(); 1174 ls.cr(); 1175 1176 shenandoah_policy()->print_gc_stats(&ls); 1177 1178 ls.cr(); 1179 ls.cr(); 1180 1181 if (ShenandoahPacing) { 1182 pacer()->print_on(&ls); 1183 } 1184 1185 ls.cr(); 1186 ls.cr(); 1187 1188 if (ShenandoahAllocationTrace) { 1189 assert(alloc_tracker() != NULL, "Must be"); 1190 alloc_tracker()->print_on(&ls); 1191 } else { 1192 ls.print_cr(" Allocation tracing is disabled, use -XX:+ShenandoahAllocationTrace to enable."); 1193 } 1194 } 1195 } 1196 1197 void ShenandoahHeap::verify(VerifyOption vo) { 1198 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) { 1199 if (ShenandoahVerify) { 1200 verifier()->verify_generic(vo); 1201 } else { 1202 // TODO: Consider allocating verification bitmaps on demand, 1203 // and turn this on unconditionally. 1204 } 1205 } 1206 } 1207 size_t ShenandoahHeap::tlab_capacity(Thread *thr) const { 1208 return _free_set->capacity(); 1209 } 1210 1211 class ObjectIterateScanRootClosure : public BasicOopIterateClosure { 1212 private: 1213 MarkBitMap* _bitmap; 1214 Stack<oop,mtGC>* _oop_stack; 1215 1216 template <class T> 1217 void do_oop_work(T* p) { 1218 T o = RawAccess<>::oop_load(p); 1219 if (!CompressedOops::is_null(o)) { 1220 oop obj = CompressedOops::decode_not_null(o); 1221 obj = ShenandoahBarrierSet::resolve_forwarded_not_null(obj); 1222 assert(oopDesc::is_oop(obj), "must be a valid oop"); 1223 if (!_bitmap->is_marked((HeapWord*) obj)) { 1224 _bitmap->mark((HeapWord*) obj); 1225 _oop_stack->push(obj); 1226 } 1227 } 1228 } 1229 public: 1230 ObjectIterateScanRootClosure(MarkBitMap* bitmap, Stack<oop,mtGC>* oop_stack) : 1231 _bitmap(bitmap), _oop_stack(oop_stack) {} 1232 void do_oop(oop* p) { do_oop_work(p); } 1233 void do_oop(narrowOop* p) { do_oop_work(p); } 1234 }; 1235 1236 /* 1237 * This is public API, used in preparation of object_iterate(). 1238 * Since we don't do linear scan of heap in object_iterate() (see comment below), we don't 1239 * need to make the heap parsable. For Shenandoah-internal linear heap scans that we can 1240 * control, we call SH::make_tlabs_parsable(). 1241 */ 1242 void ShenandoahHeap::ensure_parsability(bool retire_tlabs) { 1243 // No-op. 1244 } 1245 1246 /* 1247 * Iterates objects in the heap. This is public API, used for, e.g., heap dumping. 1248 * 1249 * We cannot safely iterate objects by doing a linear scan at random points in time. Linear 1250 * scanning needs to deal with dead objects, which may have dead Klass* pointers (e.g. 1251 * calling oopDesc::size() would crash) or dangling reference fields (crashes) etc. Linear 1252 * scanning therefore depends on having a valid marking bitmap to support it. However, we only 1253 * have a valid marking bitmap after successful marking. In particular, we *don't* have a valid 1254 * marking bitmap during marking, after aborted marking or during/after cleanup (when we just 1255 * wiped the bitmap in preparation for next marking). 1256 * 1257 * For all those reasons, we implement object iteration as a single marking traversal, reporting 1258 * objects as we mark+traverse through the heap, starting from GC roots. JVMTI IterateThroughHeap 1259 * is allowed to report dead objects, but is not required to do so. 1260 */ 1261 void ShenandoahHeap::object_iterate(ObjectClosure* cl) { 1262 assert(SafepointSynchronize::is_at_safepoint(), "safe iteration is only available during safepoints"); 1263 if (!_aux_bitmap_region_special && !os::commit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size(), false)) { 1264 log_warning(gc)("Could not commit native memory for auxiliary marking bitmap for heap iteration"); 1265 return; 1266 } 1267 1268 // Reset bitmap 1269 _aux_bit_map.clear(); 1270 1271 Stack<oop,mtGC> oop_stack; 1272 1273 // First, we process GC roots according to current GC cycle. This populates the work stack with initial objects. 1274 ShenandoahHeapIterationRootScanner rp; 1275 ObjectIterateScanRootClosure oops(&_aux_bit_map, &oop_stack); 1276 1277 if (unload_classes()) { 1278 rp.strong_roots_do(&oops); 1279 } else { 1280 rp.roots_do(&oops); 1281 } 1282 1283 // Work through the oop stack to traverse heap. 1284 while (! oop_stack.is_empty()) { 1285 oop obj = oop_stack.pop(); 1286 assert(oopDesc::is_oop(obj), "must be a valid oop"); 1287 cl->do_object(obj); 1288 obj->oop_iterate(&oops); 1289 } 1290 1291 assert(oop_stack.is_empty(), "should be empty"); 1292 1293 if (!_aux_bitmap_region_special && !os::uncommit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size())) { 1294 log_warning(gc)("Could not uncommit native memory for auxiliary marking bitmap for heap iteration"); 1295 } 1296 } 1297 1298 void ShenandoahHeap::safe_object_iterate(ObjectClosure* cl) { 1299 assert(SafepointSynchronize::is_at_safepoint(), "safe iteration is only available during safepoints"); 1300 object_iterate(cl); 1301 } 1302 1303 void ShenandoahHeap::heap_region_iterate(ShenandoahHeapRegionClosure* blk) const { 1304 for (size_t i = 0; i < num_regions(); i++) { 1305 ShenandoahHeapRegion* current = get_region(i); 1306 blk->heap_region_do(current); 1307 } 1308 } 1309 1310 class ShenandoahParallelHeapRegionTask : public AbstractGangTask { 1311 private: 1312 ShenandoahHeap* const _heap; 1313 ShenandoahHeapRegionClosure* const _blk; 1314 1315 DEFINE_PAD_MINUS_SIZE(0, DEFAULT_CACHE_LINE_SIZE, sizeof(volatile size_t)); 1316 volatile size_t _index; 1317 DEFINE_PAD_MINUS_SIZE(1, DEFAULT_CACHE_LINE_SIZE, 0); 1318 1319 public: 1320 ShenandoahParallelHeapRegionTask(ShenandoahHeapRegionClosure* blk) : 1321 AbstractGangTask("Parallel Region Task"), 1322 _heap(ShenandoahHeap::heap()), _blk(blk), _index(0) {} 1323 1324 void work(uint worker_id) { 1325 size_t stride = ShenandoahParallelRegionStride; 1326 1327 size_t max = _heap->num_regions(); 1328 while (_index < max) { 1329 size_t cur = Atomic::add(stride, &_index) - stride; 1330 size_t start = cur; 1331 size_t end = MIN2(cur + stride, max); 1332 if (start >= max) break; 1333 1334 for (size_t i = cur; i < end; i++) { 1335 ShenandoahHeapRegion* current = _heap->get_region(i); 1336 _blk->heap_region_do(current); 1337 } 1338 } 1339 } 1340 }; 1341 1342 void ShenandoahHeap::parallel_heap_region_iterate(ShenandoahHeapRegionClosure* blk) const { 1343 assert(blk->is_thread_safe(), "Only thread-safe closures here"); 1344 if (num_regions() > ShenandoahParallelRegionStride) { 1345 ShenandoahParallelHeapRegionTask task(blk); 1346 workers()->run_task(&task); 1347 } else { 1348 heap_region_iterate(blk); 1349 } 1350 } 1351 1352 class ShenandoahClearLivenessClosure : public ShenandoahHeapRegionClosure { 1353 private: 1354 ShenandoahMarkingContext* const _ctx; 1355 public: 1356 ShenandoahClearLivenessClosure() : _ctx(ShenandoahHeap::heap()->marking_context()) {} 1357 1358 void heap_region_do(ShenandoahHeapRegion* r) { 1359 if (r->is_active()) { 1360 r->clear_live_data(); 1361 _ctx->capture_top_at_mark_start(r); 1362 } else { 1363 assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->region_number()); 1364 assert(_ctx->top_at_mark_start(r) == r->top(), 1365 "Region " SIZE_FORMAT " should already have correct TAMS", r->region_number()); 1366 } 1367 } 1368 1369 bool is_thread_safe() { return true; } 1370 }; 1371 1372 void ShenandoahHeap::op_init_mark() { 1373 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should be at safepoint"); 1374 assert(Thread::current()->is_VM_thread(), "can only do this in VMThread"); 1375 1376 assert(marking_context()->is_bitmap_clear(), "need clear marking bitmap"); 1377 assert(!marking_context()->is_complete(), "should not be complete"); 1378 1379 if (ShenandoahVerify) { 1380 verifier()->verify_before_concmark(); 1381 } 1382 1383 if (VerifyBeforeGC) { 1384 Universe::verify(); 1385 } 1386 1387 set_concurrent_mark_in_progress(true); 1388 // We need to reset all TLABs because we'd lose marks on all objects allocated in them. 1389 { 1390 ShenandoahGCPhase phase(ShenandoahPhaseTimings::make_parsable); 1391 make_parsable(true); 1392 } 1393 1394 { 1395 ShenandoahGCPhase phase(ShenandoahPhaseTimings::clear_liveness); 1396 ShenandoahClearLivenessClosure clc; 1397 parallel_heap_region_iterate(&clc); 1398 } 1399 1400 // Make above changes visible to worker threads 1401 OrderAccess::fence(); 1402 1403 concurrent_mark()->mark_roots(ShenandoahPhaseTimings::scan_roots); 1404 1405 if (UseTLAB) { 1406 ShenandoahGCPhase phase(ShenandoahPhaseTimings::resize_tlabs); 1407 resize_tlabs(); 1408 } 1409 1410 if (ShenandoahPacing) { 1411 pacer()->setup_for_mark(); 1412 } 1413 } 1414 1415 void ShenandoahHeap::op_mark() { 1416 concurrent_mark()->mark_from_roots(); 1417 } 1418 1419 class ShenandoahCompleteLivenessClosure : public ShenandoahHeapRegionClosure { 1420 private: 1421 ShenandoahMarkingContext* const _ctx; 1422 public: 1423 ShenandoahCompleteLivenessClosure() : _ctx(ShenandoahHeap::heap()->complete_marking_context()) {} 1424 1425 void heap_region_do(ShenandoahHeapRegion* r) { 1426 if (r->is_active()) { 1427 HeapWord *tams = _ctx->top_at_mark_start(r); 1428 HeapWord *top = r->top(); 1429 if (top > tams) { 1430 r->increase_live_data_alloc_words(pointer_delta(top, tams)); 1431 } 1432 } else { 1433 assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->region_number()); 1434 assert(_ctx->top_at_mark_start(r) == r->top(), 1435 "Region " SIZE_FORMAT " should have correct TAMS", r->region_number()); 1436 } 1437 } 1438 1439 bool is_thread_safe() { return true; } 1440 }; 1441 1442 void ShenandoahHeap::op_final_mark() { 1443 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should be at safepoint"); 1444 1445 // It is critical that we 1446 // evacuate roots right after finishing marking, so that we don't 1447 // get unmarked objects in the roots. 1448 1449 if (!cancelled_gc()) { 1450 concurrent_mark()->finish_mark_from_roots(/* full_gc = */ false); 1451 1452 if (has_forwarded_objects()) { 1453 // Degen may be caused by failed evacuation of roots 1454 if (is_degenerated_gc_in_progress()) { 1455 concurrent_mark()->update_roots(ShenandoahPhaseTimings::degen_gc_update_roots); 1456 } else { 1457 concurrent_mark()->update_thread_roots(ShenandoahPhaseTimings::update_roots); 1458 } 1459 } 1460 1461 if (ShenandoahVerify) { 1462 verifier()->verify_roots_no_forwarded(); 1463 } 1464 1465 stop_concurrent_marking(); 1466 1467 { 1468 ShenandoahGCPhase phase(ShenandoahPhaseTimings::complete_liveness); 1469 1470 // All allocations past TAMS are implicitly live, adjust the region data. 1471 // Bitmaps/TAMS are swapped at this point, so we need to poll complete bitmap. 1472 ShenandoahCompleteLivenessClosure cl; 1473 parallel_heap_region_iterate(&cl); 1474 } 1475 1476 { 1477 ShenandoahGCPhase prepare_evac(ShenandoahPhaseTimings::prepare_evac); 1478 1479 make_parsable(true); 1480 1481 trash_cset_regions(); 1482 1483 { 1484 ShenandoahHeapLocker locker(lock()); 1485 _collection_set->clear(); 1486 _free_set->clear(); 1487 1488 heuristics()->choose_collection_set(_collection_set); 1489 1490 _free_set->rebuild(); 1491 } 1492 } 1493 1494 // If collection set has candidates, start evacuation. 1495 // Otherwise, bypass the rest of the cycle. 1496 if (!collection_set()->is_empty()) { 1497 ShenandoahGCPhase init_evac(ShenandoahPhaseTimings::init_evac); 1498 1499 if (ShenandoahVerify) { 1500 verifier()->verify_before_evacuation(); 1501 } 1502 1503 set_evacuation_in_progress(true); 1504 // From here on, we need to update references. 1505 set_has_forwarded_objects(true); 1506 1507 if (!is_degenerated_gc_in_progress()) { 1508 evacuate_and_update_roots(); 1509 } 1510 1511 if (ShenandoahPacing) { 1512 pacer()->setup_for_evac(); 1513 } 1514 1515 if (ShenandoahVerify) { 1516 if (ShenandoahConcurrentRoots::should_do_concurrent_roots()) { 1517 ShenandoahRootVerifier::RootTypes types = ShenandoahRootVerifier::combine(ShenandoahRootVerifier::JNIHandleRoots, ShenandoahRootVerifier::WeakRoots); 1518 types = ShenandoahRootVerifier::combine(types, ShenandoahRootVerifier::CLDGRoots); 1519 verifier()->verify_roots_no_forwarded_except(types); 1520 } else { 1521 verifier()->verify_roots_no_forwarded(); 1522 } 1523 verifier()->verify_during_evacuation(); 1524 } 1525 } else { 1526 if (ShenandoahVerify) { 1527 verifier()->verify_after_concmark(); 1528 } 1529 1530 if (VerifyAfterGC) { 1531 Universe::verify(); 1532 } 1533 } 1534 1535 } else { 1536 concurrent_mark()->cancel(); 1537 stop_concurrent_marking(); 1538 1539 if (process_references()) { 1540 // Abandon reference processing right away: pre-cleaning must have failed. 1541 ReferenceProcessor *rp = ref_processor(); 1542 rp->disable_discovery(); 1543 rp->abandon_partial_discovery(); 1544 rp->verify_no_references_recorded(); 1545 } 1546 } 1547 } 1548 1549 void ShenandoahHeap::op_final_evac() { 1550 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should be at safepoint"); 1551 1552 set_evacuation_in_progress(false); 1553 1554 retire_and_reset_gclabs(); 1555 1556 if (ShenandoahVerify) { 1557 verifier()->verify_after_evacuation(); 1558 } 1559 1560 if (VerifyAfterGC) { 1561 Universe::verify(); 1562 } 1563 } 1564 1565 void ShenandoahHeap::op_conc_evac() { 1566 ShenandoahEvacuationTask task(this, _collection_set, true); 1567 workers()->run_task(&task); 1568 } 1569 1570 void ShenandoahHeap::op_stw_evac() { 1571 ShenandoahEvacuationTask task(this, _collection_set, false); 1572 workers()->run_task(&task); 1573 } 1574 1575 void ShenandoahHeap::op_updaterefs() { 1576 update_heap_references(true); 1577 } 1578 1579 void ShenandoahHeap::op_cleanup() { 1580 free_set()->recycle_trash(); 1581 } 1582 1583 class ShenandoahConcurrentRootsEvacUpdateTask : public AbstractGangTask { 1584 private: 1585 ShenandoahJNIHandleRoots<true /*concurrent*/> _jni_roots; 1586 ShenandoahWeakRoots<true /*concurrent*/> _weak_roots; 1587 ShenandoahClassLoaderDataRoots<true /*concurrent*/, false /*single threaded*/> _cld_roots; 1588 1589 public: 1590 ShenandoahConcurrentRootsEvacUpdateTask() : 1591 AbstractGangTask("Shenandoah Evacuate/Update Concurrent Roots Task") { 1592 } 1593 1594 void work(uint worker_id) { 1595 ShenandoahEvacOOMScope oom; 1596 { 1597 // jni_roots and weak_roots are OopStorage backed roots, concurrent iteration 1598 // may race against OopStorage::release() calls. 1599 ShenandoahEvacUpdateOopStorageRootsClosure cl; 1600 _jni_roots.oops_do<ShenandoahEvacUpdateOopStorageRootsClosure>(&cl); 1601 _weak_roots.oops_do<ShenandoahEvacUpdateOopStorageRootsClosure>(&cl); 1602 } 1603 1604 { 1605 ShenandoahEvacuateUpdateRootsClosure cl; 1606 CLDToOopClosure clds(&cl, ClassLoaderData::_claim_strong); 1607 _cld_roots.cld_do(&clds); 1608 } 1609 } 1610 }; 1611 1612 void ShenandoahHeap::op_roots() { 1613 if (is_evacuation_in_progress() && 1614 ShenandoahConcurrentRoots::should_do_concurrent_roots()) { 1615 ShenandoahConcurrentRootsEvacUpdateTask task; 1616 workers()->run_task(&task); 1617 } 1618 } 1619 1620 void ShenandoahHeap::op_reset() { 1621 reset_mark_bitmap(); 1622 } 1623 1624 void ShenandoahHeap::op_preclean() { 1625 concurrent_mark()->preclean_weak_refs(); 1626 } 1627 1628 void ShenandoahHeap::op_init_traversal() { 1629 traversal_gc()->init_traversal_collection(); 1630 } 1631 1632 void ShenandoahHeap::op_traversal() { 1633 traversal_gc()->concurrent_traversal_collection(); 1634 } 1635 1636 void ShenandoahHeap::op_final_traversal() { 1637 traversal_gc()->final_traversal_collection(); 1638 } 1639 1640 void ShenandoahHeap::op_full(GCCause::Cause cause) { 1641 ShenandoahMetricsSnapshot metrics; 1642 metrics.snap_before(); 1643 1644 full_gc()->do_it(cause); 1645 if (UseTLAB) { 1646 ShenandoahGCPhase phase(ShenandoahPhaseTimings::full_gc_resize_tlabs); 1647 resize_all_tlabs(); 1648 } 1649 1650 metrics.snap_after(); 1651 1652 if (metrics.is_good_progress()) { 1653 _progress_last_gc.set(); 1654 } else { 1655 // Nothing to do. Tell the allocation path that we have failed to make 1656 // progress, and it can finally fail. 1657 _progress_last_gc.unset(); 1658 } 1659 } 1660 1661 void ShenandoahHeap::op_degenerated(ShenandoahDegenPoint point) { 1662 // Degenerated GC is STW, but it can also fail. Current mechanics communicates 1663 // GC failure via cancelled_concgc() flag. So, if we detect the failure after 1664 // some phase, we have to upgrade the Degenerate GC to Full GC. 1665 1666 clear_cancelled_gc(); 1667 1668 ShenandoahMetricsSnapshot metrics; 1669 metrics.snap_before(); 1670 1671 switch (point) { 1672 case _degenerated_traversal: 1673 { 1674 // Drop the collection set. Note: this leaves some already forwarded objects 1675 // behind, which may be problematic, see comments for ShenandoahEvacAssist 1676 // workarounds in ShenandoahTraversalHeuristics. 1677 1678 ShenandoahHeapLocker locker(lock()); 1679 collection_set()->clear_current_index(); 1680 for (size_t i = 0; i < collection_set()->count(); i++) { 1681 ShenandoahHeapRegion* r = collection_set()->next(); 1682 r->make_regular_bypass(); 1683 } 1684 collection_set()->clear(); 1685 } 1686 op_final_traversal(); 1687 op_cleanup(); 1688 return; 1689 1690 // The cases below form the Duff's-like device: it describes the actual GC cycle, 1691 // but enters it at different points, depending on which concurrent phase had 1692 // degenerated. 1693 1694 case _degenerated_outside_cycle: 1695 // We have degenerated from outside the cycle, which means something is bad with 1696 // the heap, most probably heavy humongous fragmentation, or we are very low on free 1697 // space. It makes little sense to wait for Full GC to reclaim as much as it can, when 1698 // we can do the most aggressive degen cycle, which includes processing references and 1699 // class unloading, unless those features are explicitly disabled. 1700 // 1701 // Note that we can only do this for "outside-cycle" degens, otherwise we would risk 1702 // changing the cycle parameters mid-cycle during concurrent -> degenerated handover. 1703 set_process_references(heuristics()->can_process_references()); 1704 set_unload_classes(heuristics()->can_unload_classes()); 1705 1706 if (is_traversal_mode()) { 1707 // Not possible to degenerate from here, upgrade to Full GC right away. 1708 cancel_gc(GCCause::_shenandoah_upgrade_to_full_gc); 1709 op_degenerated_fail(); 1710 return; 1711 } 1712 1713 op_reset(); 1714 1715 op_init_mark(); 1716 if (cancelled_gc()) { 1717 op_degenerated_fail(); 1718 return; 1719 } 1720 1721 case _degenerated_mark: 1722 op_final_mark(); 1723 if (cancelled_gc()) { 1724 op_degenerated_fail(); 1725 return; 1726 } 1727 1728 op_cleanup(); 1729 1730 case _degenerated_evac: 1731 // If heuristics thinks we should do the cycle, this flag would be set, 1732 // and we can do evacuation. Otherwise, it would be the shortcut cycle. 1733 if (is_evacuation_in_progress()) { 1734 1735 // Degeneration under oom-evac protocol might have left some objects in 1736 // collection set un-evacuated. Restart evacuation from the beginning to 1737 // capture all objects. For all the objects that are already evacuated, 1738 // it would be a simple check, which is supposed to be fast. This is also 1739 // safe to do even without degeneration, as CSet iterator is at beginning 1740 // in preparation for evacuation anyway. 1741 // 1742 // Before doing that, we need to make sure we never had any cset-pinned 1743 // regions. This may happen if allocation failure happened when evacuating 1744 // the about-to-be-pinned object, oom-evac protocol left the object in 1745 // the collection set, and then the pin reached the cset region. If we continue 1746 // the cycle here, we would trash the cset and alive objects in it. To avoid 1747 // it, we fail degeneration right away and slide into Full GC to recover. 1748 1749 { 1750 collection_set()->clear_current_index(); 1751 1752 ShenandoahHeapRegion* r; 1753 while ((r = collection_set()->next()) != NULL) { 1754 if (r->is_pinned()) { 1755 cancel_gc(GCCause::_shenandoah_upgrade_to_full_gc); 1756 op_degenerated_fail(); 1757 return; 1758 } 1759 } 1760 1761 collection_set()->clear_current_index(); 1762 } 1763 1764 op_stw_evac(); 1765 if (cancelled_gc()) { 1766 op_degenerated_fail(); 1767 return; 1768 } 1769 } 1770 1771 // If heuristics thinks we should do the cycle, this flag would be set, 1772 // and we need to do update-refs. Otherwise, it would be the shortcut cycle. 1773 if (has_forwarded_objects()) { 1774 op_init_updaterefs(); 1775 if (cancelled_gc()) { 1776 op_degenerated_fail(); 1777 return; 1778 } 1779 } 1780 1781 case _degenerated_updaterefs: 1782 if (has_forwarded_objects()) { 1783 op_final_updaterefs(); 1784 if (cancelled_gc()) { 1785 op_degenerated_fail(); 1786 return; 1787 } 1788 } 1789 1790 op_cleanup(); 1791 break; 1792 1793 default: 1794 ShouldNotReachHere(); 1795 } 1796 1797 if (ShenandoahVerify) { 1798 verifier()->verify_after_degenerated(); 1799 } 1800 1801 if (VerifyAfterGC) { 1802 Universe::verify(); 1803 } 1804 1805 metrics.snap_after(); 1806 1807 // Check for futility and fail. There is no reason to do several back-to-back Degenerated cycles, 1808 // because that probably means the heap is overloaded and/or fragmented. 1809 if (!metrics.is_good_progress()) { 1810 _progress_last_gc.unset(); 1811 cancel_gc(GCCause::_shenandoah_upgrade_to_full_gc); 1812 op_degenerated_futile(); 1813 } else { 1814 _progress_last_gc.set(); 1815 } 1816 } 1817 1818 void ShenandoahHeap::op_degenerated_fail() { 1819 log_info(gc)("Cannot finish degeneration, upgrading to Full GC"); 1820 shenandoah_policy()->record_degenerated_upgrade_to_full(); 1821 op_full(GCCause::_shenandoah_upgrade_to_full_gc); 1822 } 1823 1824 void ShenandoahHeap::op_degenerated_futile() { 1825 shenandoah_policy()->record_degenerated_upgrade_to_full(); 1826 op_full(GCCause::_shenandoah_upgrade_to_full_gc); 1827 } 1828 1829 void ShenandoahHeap::stop_concurrent_marking() { 1830 assert(is_concurrent_mark_in_progress(), "How else could we get here?"); 1831 set_concurrent_mark_in_progress(false); 1832 if (!cancelled_gc()) { 1833 // If we needed to update refs, and concurrent marking has been cancelled, 1834 // we need to finish updating references. 1835 set_has_forwarded_objects(false); 1836 mark_complete_marking_context(); 1837 } 1838 } 1839 1840 void ShenandoahHeap::force_satb_flush_all_threads() { 1841 if (!is_concurrent_mark_in_progress() && !is_concurrent_traversal_in_progress()) { 1842 // No need to flush SATBs 1843 return; 1844 } 1845 1846 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) { 1847 ShenandoahThreadLocalData::set_force_satb_flush(t, true); 1848 } 1849 // The threads are not "acquiring" their thread-local data, but it does not 1850 // hurt to "release" the updates here anyway. 1851 OrderAccess::fence(); 1852 } 1853 1854 void ShenandoahHeap::set_gc_state_all_threads(char state) { 1855 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) { 1856 ShenandoahThreadLocalData::set_gc_state(t, state); 1857 } 1858 } 1859 1860 void ShenandoahHeap::set_gc_state_mask(uint mask, bool value) { 1861 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should really be Shenandoah safepoint"); 1862 _gc_state.set_cond(mask, value); 1863 set_gc_state_all_threads(_gc_state.raw_value()); 1864 } 1865 1866 void ShenandoahHeap::set_concurrent_mark_in_progress(bool in_progress) { 1867 if (has_forwarded_objects()) { 1868 set_gc_state_mask(MARKING | UPDATEREFS, in_progress); 1869 } else { 1870 set_gc_state_mask(MARKING, in_progress); 1871 } 1872 ShenandoahBarrierSet::satb_mark_queue_set().set_active_all_threads(in_progress, !in_progress); 1873 } 1874 1875 void ShenandoahHeap::set_concurrent_traversal_in_progress(bool in_progress) { 1876 set_gc_state_mask(TRAVERSAL | HAS_FORWARDED | UPDATEREFS, in_progress); 1877 ShenandoahBarrierSet::satb_mark_queue_set().set_active_all_threads(in_progress, !in_progress); 1878 } 1879 1880 void ShenandoahHeap::set_evacuation_in_progress(bool in_progress) { 1881 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Only call this at safepoint"); 1882 set_gc_state_mask(EVACUATION, in_progress); 1883 } 1884 1885 void ShenandoahHeap::ref_processing_init() { 1886 assert(_max_workers > 0, "Sanity"); 1887 1888 _ref_processor = 1889 new ReferenceProcessor(&_subject_to_discovery, // is_subject_to_discovery 1890 ParallelRefProcEnabled, // MT processing 1891 _max_workers, // Degree of MT processing 1892 true, // MT discovery 1893 _max_workers, // Degree of MT discovery 1894 false, // Reference discovery is not atomic 1895 NULL, // No closure, should be installed before use 1896 true); // Scale worker threads 1897 1898 shenandoah_assert_rp_isalive_not_installed(); 1899 } 1900 1901 GCTracer* ShenandoahHeap::tracer() { 1902 return shenandoah_policy()->tracer(); 1903 } 1904 1905 size_t ShenandoahHeap::tlab_used(Thread* thread) const { 1906 return _free_set->used(); 1907 } 1908 1909 bool ShenandoahHeap::try_cancel_gc() { 1910 while (true) { 1911 jbyte prev = _cancelled_gc.cmpxchg(CANCELLED, CANCELLABLE); 1912 if (prev == CANCELLABLE) return true; 1913 else if (prev == CANCELLED) return false; 1914 assert(ShenandoahSuspendibleWorkers, "should not get here when not using suspendible workers"); 1915 assert(prev == NOT_CANCELLED, "must be NOT_CANCELLED"); 1916 { 1917 // We need to provide a safepoint here, otherwise we might 1918 // spin forever if a SP is pending. 1919 ThreadBlockInVM sp(JavaThread::current()); 1920 SpinPause(); 1921 } 1922 } 1923 } 1924 1925 void ShenandoahHeap::cancel_gc(GCCause::Cause cause) { 1926 if (try_cancel_gc()) { 1927 FormatBuffer<> msg("Cancelling GC: %s", GCCause::to_string(cause)); 1928 log_info(gc)("%s", msg.buffer()); 1929 Events::log(Thread::current(), "%s", msg.buffer()); 1930 } 1931 } 1932 1933 uint ShenandoahHeap::max_workers() { 1934 return _max_workers; 1935 } 1936 1937 void ShenandoahHeap::stop() { 1938 // The shutdown sequence should be able to terminate when GC is running. 1939 1940 // Step 0. Notify policy to disable event recording. 1941 _shenandoah_policy->record_shutdown(); 1942 1943 // Step 1. Notify control thread that we are in shutdown. 1944 // Note that we cannot do that with stop(), because stop() is blocking and waits for the actual shutdown. 1945 // Doing stop() here would wait for the normal GC cycle to complete, never falling through to cancel below. 1946 control_thread()->prepare_for_graceful_shutdown(); 1947 1948 // Step 2. Notify GC workers that we are cancelling GC. 1949 cancel_gc(GCCause::_shenandoah_stop_vm); 1950 1951 // Step 3. Wait until GC worker exits normally. 1952 control_thread()->stop(); 1953 1954 // Step 4. Stop String Dedup thread if it is active 1955 if (ShenandoahStringDedup::is_enabled()) { 1956 ShenandoahStringDedup::stop(); 1957 } 1958 } 1959 1960 void ShenandoahHeap::stw_unload_classes(bool full_gc) { 1961 if (!unload_classes()) return; 1962 bool purged_class; 1963 1964 // Unload classes and purge SystemDictionary. 1965 { 1966 ShenandoahGCPhase phase(full_gc ? 1967 ShenandoahPhaseTimings::full_gc_purge_class_unload : 1968 ShenandoahPhaseTimings::purge_class_unload); 1969 purged_class = SystemDictionary::do_unloading(gc_timer()); 1970 } 1971 1972 { 1973 ShenandoahGCPhase phase(full_gc ? 1974 ShenandoahPhaseTimings::full_gc_purge_par : 1975 ShenandoahPhaseTimings::purge_par); 1976 ShenandoahIsAliveSelector is_alive; 1977 uint num_workers = _workers->active_workers(); 1978 ShenandoahClassUnloadingTask unlink_task(is_alive.is_alive_closure(), num_workers, purged_class); 1979 _workers->run_task(&unlink_task); 1980 } 1981 1982 { 1983 ShenandoahGCPhase phase(full_gc ? 1984 ShenandoahPhaseTimings::full_gc_purge_cldg : 1985 ShenandoahPhaseTimings::purge_cldg); 1986 ClassLoaderDataGraph::purge(); 1987 } 1988 // Resize and verify metaspace 1989 MetaspaceGC::compute_new_size(); 1990 MetaspaceUtils::verify_metrics(); 1991 } 1992 1993 // Process leftover weak oops: update them, if needed or assert they do not 1994 // need updating otherwise. 1995 // Weak processor API requires us to visit the oops, even if we are not doing 1996 // anything to them. 1997 void ShenandoahHeap::stw_process_weak_roots(bool full_gc) { 1998 ShenandoahGCPhase root_phase(full_gc ? 1999 ShenandoahPhaseTimings::full_gc_purge : 2000 ShenandoahPhaseTimings::purge); 2001 uint num_workers = _workers->active_workers(); 2002 ShenandoahPhaseTimings::Phase timing_phase = full_gc ? 2003 ShenandoahPhaseTimings::full_gc_purge_par : 2004 ShenandoahPhaseTimings::purge_par; 2005 // Cleanup weak roots 2006 ShenandoahGCPhase phase(timing_phase); 2007 if (has_forwarded_objects()) { 2008 ShenandoahForwardedIsAliveClosure is_alive; 2009 ShenandoahUpdateRefsClosure keep_alive; 2010 ShenandoahParallelWeakRootsCleaningTask<ShenandoahForwardedIsAliveClosure, ShenandoahUpdateRefsClosure> 2011 cleaning_task(&is_alive, &keep_alive, num_workers); 2012 _workers->run_task(&cleaning_task); 2013 } else { 2014 ShenandoahIsAliveClosure is_alive; 2015 #ifdef ASSERT 2016 ShenandoahAssertNotForwardedClosure verify_cl; 2017 ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, ShenandoahAssertNotForwardedClosure> 2018 cleaning_task(&is_alive, &verify_cl, num_workers); 2019 #else 2020 ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, DoNothingClosure> 2021 cleaning_task(&is_alive, &do_nothing_cl, num_workers); 2022 #endif 2023 _workers->run_task(&cleaning_task); 2024 } 2025 } 2026 2027 void ShenandoahHeap::parallel_cleaning(bool full_gc) { 2028 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint"); 2029 stw_process_weak_roots(full_gc); 2030 stw_unload_classes(full_gc); 2031 } 2032 2033 void ShenandoahHeap::set_has_forwarded_objects(bool cond) { 2034 set_gc_state_mask(HAS_FORWARDED, cond); 2035 } 2036 2037 void ShenandoahHeap::set_process_references(bool pr) { 2038 _process_references.set_cond(pr); 2039 } 2040 2041 void ShenandoahHeap::set_unload_classes(bool uc) { 2042 _unload_classes.set_cond(uc); 2043 } 2044 2045 bool ShenandoahHeap::process_references() const { 2046 return _process_references.is_set(); 2047 } 2048 2049 bool ShenandoahHeap::unload_classes() const { 2050 return _unload_classes.is_set(); 2051 } 2052 2053 address ShenandoahHeap::in_cset_fast_test_addr() { 2054 ShenandoahHeap* heap = ShenandoahHeap::heap(); 2055 assert(heap->collection_set() != NULL, "Sanity"); 2056 return (address) heap->collection_set()->biased_map_address(); 2057 } 2058 2059 address ShenandoahHeap::cancelled_gc_addr() { 2060 return (address) ShenandoahHeap::heap()->_cancelled_gc.addr_of(); 2061 } 2062 2063 address ShenandoahHeap::gc_state_addr() { 2064 return (address) ShenandoahHeap::heap()->_gc_state.addr_of(); 2065 } 2066 2067 size_t ShenandoahHeap::bytes_allocated_since_gc_start() { 2068 return OrderAccess::load_acquire(&_bytes_allocated_since_gc_start); 2069 } 2070 2071 void ShenandoahHeap::reset_bytes_allocated_since_gc_start() { 2072 OrderAccess::release_store_fence(&_bytes_allocated_since_gc_start, (size_t)0); 2073 } 2074 2075 void ShenandoahHeap::set_degenerated_gc_in_progress(bool in_progress) { 2076 _degenerated_gc_in_progress.set_cond(in_progress); 2077 } 2078 2079 void ShenandoahHeap::set_full_gc_in_progress(bool in_progress) { 2080 _full_gc_in_progress.set_cond(in_progress); 2081 } 2082 2083 void ShenandoahHeap::set_full_gc_move_in_progress(bool in_progress) { 2084 assert (is_full_gc_in_progress(), "should be"); 2085 _full_gc_move_in_progress.set_cond(in_progress); 2086 } 2087 2088 void ShenandoahHeap::set_update_refs_in_progress(bool in_progress) { 2089 set_gc_state_mask(UPDATEREFS, in_progress); 2090 } 2091 2092 void ShenandoahHeap::register_nmethod(nmethod* nm) { 2093 ShenandoahCodeRoots::add_nmethod(nm); 2094 } 2095 2096 void ShenandoahHeap::unregister_nmethod(nmethod* nm) { 2097 ShenandoahCodeRoots::remove_nmethod(nm); 2098 } 2099 2100 oop ShenandoahHeap::pin_object(JavaThread* thr, oop o) { 2101 ShenandoahHeapLocker locker(lock()); 2102 heap_region_containing(o)->make_pinned(); 2103 return o; 2104 } 2105 2106 void ShenandoahHeap::unpin_object(JavaThread* thr, oop o) { 2107 ShenandoahHeapLocker locker(lock()); 2108 heap_region_containing(o)->make_unpinned(); 2109 } 2110 2111 GCTimer* ShenandoahHeap::gc_timer() const { 2112 return _gc_timer; 2113 } 2114 2115 #ifdef ASSERT 2116 void ShenandoahHeap::assert_gc_workers(uint nworkers) { 2117 assert(nworkers > 0 && nworkers <= max_workers(), "Sanity"); 2118 2119 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) { 2120 if (UseDynamicNumberOfGCThreads || 2121 (FLAG_IS_DEFAULT(ParallelGCThreads) && ForceDynamicNumberOfGCThreads)) { 2122 assert(nworkers <= ParallelGCThreads, "Cannot use more than it has"); 2123 } else { 2124 // Use ParallelGCThreads inside safepoints 2125 assert(nworkers == ParallelGCThreads, "Use ParalleGCThreads within safepoints"); 2126 } 2127 } else { 2128 if (UseDynamicNumberOfGCThreads || 2129 (FLAG_IS_DEFAULT(ConcGCThreads) && ForceDynamicNumberOfGCThreads)) { 2130 assert(nworkers <= ConcGCThreads, "Cannot use more than it has"); 2131 } else { 2132 // Use ConcGCThreads outside safepoints 2133 assert(nworkers == ConcGCThreads, "Use ConcGCThreads outside safepoints"); 2134 } 2135 } 2136 } 2137 #endif 2138 2139 ShenandoahVerifier* ShenandoahHeap::verifier() { 2140 guarantee(ShenandoahVerify, "Should be enabled"); 2141 assert (_verifier != NULL, "sanity"); 2142 return _verifier; 2143 } 2144 2145 template<class T> 2146 class ShenandoahUpdateHeapRefsTask : public AbstractGangTask { 2147 private: 2148 T cl; 2149 ShenandoahHeap* _heap; 2150 ShenandoahRegionIterator* _regions; 2151 bool _concurrent; 2152 public: 2153 ShenandoahUpdateHeapRefsTask(ShenandoahRegionIterator* regions, bool concurrent) : 2154 AbstractGangTask("Concurrent Update References Task"), 2155 cl(T()), 2156 _heap(ShenandoahHeap::heap()), 2157 _regions(regions), 2158 _concurrent(concurrent) { 2159 } 2160 2161 void work(uint worker_id) { 2162 if (_concurrent) { 2163 ShenandoahConcurrentWorkerSession worker_session(worker_id); 2164 ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers); 2165 do_work(); 2166 } else { 2167 ShenandoahParallelWorkerSession worker_session(worker_id); 2168 do_work(); 2169 } 2170 } 2171 2172 private: 2173 void do_work() { 2174 ShenandoahHeapRegion* r = _regions->next(); 2175 ShenandoahMarkingContext* const ctx = _heap->complete_marking_context(); 2176 while (r != NULL) { 2177 HeapWord* top_at_start_ur = r->concurrent_iteration_safe_limit(); 2178 assert (top_at_start_ur >= r->bottom(), "sanity"); 2179 if (r->is_active() && !r->is_cset()) { 2180 _heap->marked_object_oop_iterate(r, &cl, top_at_start_ur); 2181 } 2182 if (ShenandoahPacing) { 2183 _heap->pacer()->report_updaterefs(pointer_delta(top_at_start_ur, r->bottom())); 2184 } 2185 if (_heap->check_cancelled_gc_and_yield(_concurrent)) { 2186 return; 2187 } 2188 r = _regions->next(); 2189 } 2190 } 2191 }; 2192 2193 void ShenandoahHeap::update_heap_references(bool concurrent) { 2194 ShenandoahUpdateHeapRefsTask<ShenandoahUpdateHeapRefsClosure> task(&_update_refs_iterator, concurrent); 2195 workers()->run_task(&task); 2196 } 2197 2198 void ShenandoahHeap::op_init_updaterefs() { 2199 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint"); 2200 2201 set_evacuation_in_progress(false); 2202 2203 retire_and_reset_gclabs(); 2204 2205 if (ShenandoahVerify) { 2206 if (!is_degenerated_gc_in_progress()) { 2207 verifier()->verify_roots_no_forwarded_except(ShenandoahRootVerifier::ThreadRoots); 2208 } 2209 verifier()->verify_before_updaterefs(); 2210 } 2211 2212 set_update_refs_in_progress(true); 2213 make_parsable(true); 2214 for (uint i = 0; i < num_regions(); i++) { 2215 ShenandoahHeapRegion* r = get_region(i); 2216 r->set_concurrent_iteration_safe_limit(r->top()); 2217 } 2218 2219 // Reset iterator. 2220 _update_refs_iterator.reset(); 2221 2222 if (ShenandoahPacing) { 2223 pacer()->setup_for_updaterefs(); 2224 } 2225 } 2226 2227 void ShenandoahHeap::op_final_updaterefs() { 2228 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint"); 2229 2230 // Check if there is left-over work, and finish it 2231 if (_update_refs_iterator.has_next()) { 2232 ShenandoahGCPhase final_work(ShenandoahPhaseTimings::final_update_refs_finish_work); 2233 2234 // Finish updating references where we left off. 2235 clear_cancelled_gc(); 2236 update_heap_references(false); 2237 } 2238 2239 // Clear cancelled GC, if set. On cancellation path, the block before would handle 2240 // everything. On degenerated paths, cancelled gc would not be set anyway. 2241 if (cancelled_gc()) { 2242 clear_cancelled_gc(); 2243 } 2244 assert(!cancelled_gc(), "Should have been done right before"); 2245 2246 if (ShenandoahVerify && !is_degenerated_gc_in_progress()) { 2247 verifier()->verify_roots_no_forwarded_except(ShenandoahRootVerifier::ThreadRoots); 2248 } 2249 2250 if (is_degenerated_gc_in_progress()) { 2251 concurrent_mark()->update_roots(ShenandoahPhaseTimings::degen_gc_update_roots); 2252 } else { 2253 concurrent_mark()->update_thread_roots(ShenandoahPhaseTimings::final_update_refs_roots); 2254 } 2255 2256 // Has to be done before cset is clear 2257 if (ShenandoahVerify) { 2258 verifier()->verify_roots_in_to_space(); 2259 } 2260 2261 ShenandoahGCPhase final_update_refs(ShenandoahPhaseTimings::final_update_refs_recycle); 2262 2263 trash_cset_regions(); 2264 set_has_forwarded_objects(false); 2265 set_update_refs_in_progress(false); 2266 2267 if (ShenandoahVerify) { 2268 verifier()->verify_after_updaterefs(); 2269 } 2270 2271 if (VerifyAfterGC) { 2272 Universe::verify(); 2273 } 2274 2275 { 2276 ShenandoahHeapLocker locker(lock()); 2277 _free_set->rebuild(); 2278 } 2279 } 2280 2281 #ifdef ASSERT 2282 void ShenandoahHeap::assert_heaplock_owned_by_current_thread() { 2283 _lock.assert_owned_by_current_thread(); 2284 } 2285 2286 void ShenandoahHeap::assert_heaplock_not_owned_by_current_thread() { 2287 _lock.assert_not_owned_by_current_thread(); 2288 } 2289 2290 void ShenandoahHeap::assert_heaplock_or_safepoint() { 2291 _lock.assert_owned_by_current_thread_or_safepoint(); 2292 } 2293 #endif 2294 2295 void ShenandoahHeap::print_extended_on(outputStream *st) const { 2296 print_on(st); 2297 print_heap_regions_on(st); 2298 } 2299 2300 bool ShenandoahHeap::is_bitmap_slice_committed(ShenandoahHeapRegion* r, bool skip_self) { 2301 size_t slice = r->region_number() / _bitmap_regions_per_slice; 2302 2303 size_t regions_from = _bitmap_regions_per_slice * slice; 2304 size_t regions_to = MIN2(num_regions(), _bitmap_regions_per_slice * (slice + 1)); 2305 for (size_t g = regions_from; g < regions_to; g++) { 2306 assert (g / _bitmap_regions_per_slice == slice, "same slice"); 2307 if (skip_self && g == r->region_number()) continue; 2308 if (get_region(g)->is_committed()) { 2309 return true; 2310 } 2311 } 2312 return false; 2313 } 2314 2315 bool ShenandoahHeap::commit_bitmap_slice(ShenandoahHeapRegion* r) { 2316 assert_heaplock_owned_by_current_thread(); 2317 2318 // Bitmaps in special regions do not need commits 2319 if (_bitmap_region_special) { 2320 return true; 2321 } 2322 2323 if (is_bitmap_slice_committed(r, true)) { 2324 // Some other region from the group is already committed, meaning the bitmap 2325 // slice is already committed, we exit right away. 2326 return true; 2327 } 2328 2329 // Commit the bitmap slice: 2330 size_t slice = r->region_number() / _bitmap_regions_per_slice; 2331 size_t off = _bitmap_bytes_per_slice * slice; 2332 size_t len = _bitmap_bytes_per_slice; 2333 if (!os::commit_memory((char*)_bitmap_region.start() + off, len, false)) { 2334 return false; 2335 } 2336 return true; 2337 } 2338 2339 bool ShenandoahHeap::uncommit_bitmap_slice(ShenandoahHeapRegion *r) { 2340 assert_heaplock_owned_by_current_thread(); 2341 2342 // Bitmaps in special regions do not need uncommits 2343 if (_bitmap_region_special) { 2344 return true; 2345 } 2346 2347 if (is_bitmap_slice_committed(r, true)) { 2348 // Some other region from the group is still committed, meaning the bitmap 2349 // slice is should stay committed, exit right away. 2350 return true; 2351 } 2352 2353 // Uncommit the bitmap slice: 2354 size_t slice = r->region_number() / _bitmap_regions_per_slice; 2355 size_t off = _bitmap_bytes_per_slice * slice; 2356 size_t len = _bitmap_bytes_per_slice; 2357 if (!os::uncommit_memory((char*)_bitmap_region.start() + off, len)) { 2358 return false; 2359 } 2360 return true; 2361 } 2362 2363 void ShenandoahHeap::safepoint_synchronize_begin() { 2364 if (ShenandoahSuspendibleWorkers || UseStringDeduplication) { 2365 SuspendibleThreadSet::synchronize(); 2366 } 2367 } 2368 2369 void ShenandoahHeap::safepoint_synchronize_end() { 2370 if (ShenandoahSuspendibleWorkers || UseStringDeduplication) { 2371 SuspendibleThreadSet::desynchronize(); 2372 } 2373 } 2374 2375 void ShenandoahHeap::vmop_entry_init_mark() { 2376 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters()); 2377 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross); 2378 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_mark_gross); 2379 2380 try_inject_alloc_failure(); 2381 VM_ShenandoahInitMark op; 2382 VMThread::execute(&op); // jump to entry_init_mark() under safepoint 2383 } 2384 2385 void ShenandoahHeap::vmop_entry_final_mark() { 2386 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters()); 2387 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross); 2388 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_mark_gross); 2389 2390 try_inject_alloc_failure(); 2391 VM_ShenandoahFinalMarkStartEvac op; 2392 VMThread::execute(&op); // jump to entry_final_mark under safepoint 2393 } 2394 2395 void ShenandoahHeap::vmop_entry_final_evac() { 2396 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters()); 2397 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross); 2398 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_evac_gross); 2399 2400 VM_ShenandoahFinalEvac op; 2401 VMThread::execute(&op); // jump to entry_final_evac under safepoint 2402 } 2403 2404 void ShenandoahHeap::vmop_entry_init_updaterefs() { 2405 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters()); 2406 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross); 2407 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_refs_gross); 2408 2409 try_inject_alloc_failure(); 2410 VM_ShenandoahInitUpdateRefs op; 2411 VMThread::execute(&op); 2412 } 2413 2414 void ShenandoahHeap::vmop_entry_final_updaterefs() { 2415 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters()); 2416 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross); 2417 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_gross); 2418 2419 try_inject_alloc_failure(); 2420 VM_ShenandoahFinalUpdateRefs op; 2421 VMThread::execute(&op); 2422 } 2423 2424 void ShenandoahHeap::vmop_entry_init_traversal() { 2425 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters()); 2426 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross); 2427 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_traversal_gc_gross); 2428 2429 try_inject_alloc_failure(); 2430 VM_ShenandoahInitTraversalGC op; 2431 VMThread::execute(&op); 2432 } 2433 2434 void ShenandoahHeap::vmop_entry_final_traversal() { 2435 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters()); 2436 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross); 2437 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_traversal_gc_gross); 2438 2439 try_inject_alloc_failure(); 2440 VM_ShenandoahFinalTraversalGC op; 2441 VMThread::execute(&op); 2442 } 2443 2444 void ShenandoahHeap::vmop_entry_full(GCCause::Cause cause) { 2445 TraceCollectorStats tcs(monitoring_support()->full_stw_collection_counters()); 2446 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross); 2447 ShenandoahGCPhase phase(ShenandoahPhaseTimings::full_gc_gross); 2448 2449 try_inject_alloc_failure(); 2450 VM_ShenandoahFullGC op(cause); 2451 VMThread::execute(&op); 2452 } 2453 2454 void ShenandoahHeap::vmop_degenerated(ShenandoahDegenPoint point) { 2455 TraceCollectorStats tcs(monitoring_support()->full_stw_collection_counters()); 2456 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross); 2457 ShenandoahGCPhase phase(ShenandoahPhaseTimings::degen_gc_gross); 2458 2459 VM_ShenandoahDegeneratedGC degenerated_gc((int)point); 2460 VMThread::execute(°enerated_gc); 2461 } 2462 2463 void ShenandoahHeap::entry_init_mark() { 2464 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause); 2465 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_mark); 2466 const char* msg = init_mark_event_message(); 2467 GCTraceTime(Info, gc) time(msg, gc_timer()); 2468 EventMark em("%s", msg); 2469 2470 ShenandoahWorkerScope scope(workers(), 2471 ShenandoahWorkerPolicy::calc_workers_for_init_marking(), 2472 "init marking"); 2473 2474 op_init_mark(); 2475 } 2476 2477 void ShenandoahHeap::entry_final_mark() { 2478 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause); 2479 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_mark); 2480 const char* msg = final_mark_event_message(); 2481 GCTraceTime(Info, gc) time(msg, gc_timer()); 2482 EventMark em("%s", msg); 2483 2484 ShenandoahWorkerScope scope(workers(), 2485 ShenandoahWorkerPolicy::calc_workers_for_final_marking(), 2486 "final marking"); 2487 2488 op_final_mark(); 2489 } 2490 2491 void ShenandoahHeap::entry_final_evac() { 2492 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause); 2493 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_evac); 2494 static const char* msg = "Pause Final Evac"; 2495 GCTraceTime(Info, gc) time(msg, gc_timer()); 2496 EventMark em("%s", msg); 2497 2498 op_final_evac(); 2499 } 2500 2501 void ShenandoahHeap::entry_init_updaterefs() { 2502 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause); 2503 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_refs); 2504 2505 static const char* msg = "Pause Init Update Refs"; 2506 GCTraceTime(Info, gc) time(msg, gc_timer()); 2507 EventMark em("%s", msg); 2508 2509 // No workers used in this phase, no setup required 2510 2511 op_init_updaterefs(); 2512 } 2513 2514 void ShenandoahHeap::entry_final_updaterefs() { 2515 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause); 2516 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs); 2517 2518 static const char* msg = "Pause Final Update Refs"; 2519 GCTraceTime(Info, gc) time(msg, gc_timer()); 2520 EventMark em("%s", msg); 2521 2522 ShenandoahWorkerScope scope(workers(), 2523 ShenandoahWorkerPolicy::calc_workers_for_final_update_ref(), 2524 "final reference update"); 2525 2526 op_final_updaterefs(); 2527 } 2528 2529 void ShenandoahHeap::entry_init_traversal() { 2530 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause); 2531 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_traversal_gc); 2532 2533 static const char* msg = "Pause Init Traversal"; 2534 GCTraceTime(Info, gc) time(msg, gc_timer()); 2535 EventMark em("%s", msg); 2536 2537 ShenandoahWorkerScope scope(workers(), 2538 ShenandoahWorkerPolicy::calc_workers_for_stw_traversal(), 2539 "init traversal"); 2540 2541 op_init_traversal(); 2542 } 2543 2544 void ShenandoahHeap::entry_final_traversal() { 2545 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause); 2546 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_traversal_gc); 2547 2548 static const char* msg = "Pause Final Traversal"; 2549 GCTraceTime(Info, gc) time(msg, gc_timer()); 2550 EventMark em("%s", msg); 2551 2552 ShenandoahWorkerScope scope(workers(), 2553 ShenandoahWorkerPolicy::calc_workers_for_stw_traversal(), 2554 "final traversal"); 2555 2556 op_final_traversal(); 2557 } 2558 2559 void ShenandoahHeap::entry_full(GCCause::Cause cause) { 2560 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause); 2561 ShenandoahGCPhase phase(ShenandoahPhaseTimings::full_gc); 2562 2563 static const char* msg = "Pause Full"; 2564 GCTraceTime(Info, gc) time(msg, gc_timer(), cause, true); 2565 EventMark em("%s", msg); 2566 2567 ShenandoahWorkerScope scope(workers(), 2568 ShenandoahWorkerPolicy::calc_workers_for_fullgc(), 2569 "full gc"); 2570 2571 op_full(cause); 2572 } 2573 2574 void ShenandoahHeap::entry_degenerated(int point) { 2575 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause); 2576 ShenandoahGCPhase phase(ShenandoahPhaseTimings::degen_gc); 2577 2578 ShenandoahDegenPoint dpoint = (ShenandoahDegenPoint)point; 2579 const char* msg = degen_event_message(dpoint); 2580 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true); 2581 EventMark em("%s", msg); 2582 2583 ShenandoahWorkerScope scope(workers(), 2584 ShenandoahWorkerPolicy::calc_workers_for_stw_degenerated(), 2585 "stw degenerated gc"); 2586 2587 set_degenerated_gc_in_progress(true); 2588 op_degenerated(dpoint); 2589 set_degenerated_gc_in_progress(false); 2590 } 2591 2592 void ShenandoahHeap::entry_mark() { 2593 TraceCollectorStats tcs(monitoring_support()->concurrent_collection_counters()); 2594 2595 const char* msg = conc_mark_event_message(); 2596 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true); 2597 EventMark em("%s", msg); 2598 2599 ShenandoahWorkerScope scope(workers(), 2600 ShenandoahWorkerPolicy::calc_workers_for_conc_marking(), 2601 "concurrent marking"); 2602 2603 try_inject_alloc_failure(); 2604 op_mark(); 2605 } 2606 2607 void ShenandoahHeap::entry_evac() { 2608 ShenandoahGCPhase conc_evac_phase(ShenandoahPhaseTimings::conc_evac); 2609 TraceCollectorStats tcs(monitoring_support()->concurrent_collection_counters()); 2610 2611 static const char* msg = "Concurrent evacuation"; 2612 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true); 2613 EventMark em("%s", msg); 2614 2615 ShenandoahWorkerScope scope(workers(), 2616 ShenandoahWorkerPolicy::calc_workers_for_conc_evac(), 2617 "concurrent evacuation"); 2618 2619 try_inject_alloc_failure(); 2620 op_conc_evac(); 2621 } 2622 2623 void ShenandoahHeap::entry_updaterefs() { 2624 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_update_refs); 2625 2626 static const char* msg = "Concurrent update references"; 2627 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true); 2628 EventMark em("%s", msg); 2629 2630 ShenandoahWorkerScope scope(workers(), 2631 ShenandoahWorkerPolicy::calc_workers_for_conc_update_ref(), 2632 "concurrent reference update"); 2633 2634 try_inject_alloc_failure(); 2635 op_updaterefs(); 2636 } 2637 2638 void ShenandoahHeap::entry_roots() { 2639 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_roots); 2640 2641 static const char* msg = "Concurrent roots processing"; 2642 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true); 2643 EventMark em("%s", msg); 2644 2645 ShenandoahWorkerScope scope(workers(), 2646 ShenandoahWorkerPolicy::calc_workers_for_conc_root_processing(), 2647 "concurrent root processing"); 2648 2649 try_inject_alloc_failure(); 2650 op_roots(); 2651 } 2652 2653 void ShenandoahHeap::entry_cleanup() { 2654 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_cleanup); 2655 2656 static const char* msg = "Concurrent cleanup"; 2657 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true); 2658 EventMark em("%s", msg); 2659 2660 // This phase does not use workers, no need for setup 2661 2662 try_inject_alloc_failure(); 2663 op_cleanup(); 2664 } 2665 2666 void ShenandoahHeap::entry_reset() { 2667 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_reset); 2668 2669 static const char* msg = "Concurrent reset"; 2670 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true); 2671 EventMark em("%s", msg); 2672 2673 ShenandoahWorkerScope scope(workers(), 2674 ShenandoahWorkerPolicy::calc_workers_for_conc_reset(), 2675 "concurrent reset"); 2676 2677 try_inject_alloc_failure(); 2678 op_reset(); 2679 } 2680 2681 void ShenandoahHeap::entry_preclean() { 2682 if (ShenandoahPreclean && process_references()) { 2683 static const char* msg = "Concurrent precleaning"; 2684 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true); 2685 EventMark em("%s", msg); 2686 2687 ShenandoahGCPhase conc_preclean(ShenandoahPhaseTimings::conc_preclean); 2688 2689 ShenandoahWorkerScope scope(workers(), 2690 ShenandoahWorkerPolicy::calc_workers_for_conc_preclean(), 2691 "concurrent preclean", 2692 /* check_workers = */ false); 2693 2694 try_inject_alloc_failure(); 2695 op_preclean(); 2696 } 2697 } 2698 2699 void ShenandoahHeap::entry_traversal() { 2700 static const char* msg = "Concurrent traversal"; 2701 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true); 2702 EventMark em("%s", msg); 2703 2704 TraceCollectorStats tcs(monitoring_support()->concurrent_collection_counters()); 2705 2706 ShenandoahWorkerScope scope(workers(), 2707 ShenandoahWorkerPolicy::calc_workers_for_conc_traversal(), 2708 "concurrent traversal"); 2709 2710 try_inject_alloc_failure(); 2711 op_traversal(); 2712 } 2713 2714 void ShenandoahHeap::entry_uncommit(double shrink_before) { 2715 static const char *msg = "Concurrent uncommit"; 2716 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true); 2717 EventMark em("%s", msg); 2718 2719 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_uncommit); 2720 2721 op_uncommit(shrink_before); 2722 } 2723 2724 void ShenandoahHeap::try_inject_alloc_failure() { 2725 if (ShenandoahAllocFailureALot && !cancelled_gc() && ((os::random() % 1000) > 950)) { 2726 _inject_alloc_failure.set(); 2727 os::naked_short_sleep(1); 2728 if (cancelled_gc()) { 2729 log_info(gc)("Allocation failure was successfully injected"); 2730 } 2731 } 2732 } 2733 2734 bool ShenandoahHeap::should_inject_alloc_failure() { 2735 return _inject_alloc_failure.is_set() && _inject_alloc_failure.try_unset(); 2736 } 2737 2738 void ShenandoahHeap::initialize_serviceability() { 2739 _memory_pool = new ShenandoahMemoryPool(this); 2740 _cycle_memory_manager.add_pool(_memory_pool); 2741 _stw_memory_manager.add_pool(_memory_pool); 2742 } 2743 2744 GrowableArray<GCMemoryManager*> ShenandoahHeap::memory_managers() { 2745 GrowableArray<GCMemoryManager*> memory_managers(2); 2746 memory_managers.append(&_cycle_memory_manager); 2747 memory_managers.append(&_stw_memory_manager); 2748 return memory_managers; 2749 } 2750 2751 GrowableArray<MemoryPool*> ShenandoahHeap::memory_pools() { 2752 GrowableArray<MemoryPool*> memory_pools(1); 2753 memory_pools.append(_memory_pool); 2754 return memory_pools; 2755 } 2756 2757 MemoryUsage ShenandoahHeap::memory_usage() { 2758 return _memory_pool->get_memory_usage(); 2759 } 2760 2761 void ShenandoahHeap::enter_evacuation() { 2762 _oom_evac_handler.enter_evacuation(); 2763 } 2764 2765 void ShenandoahHeap::leave_evacuation() { 2766 _oom_evac_handler.leave_evacuation(); 2767 } 2768 2769 ShenandoahRegionIterator::ShenandoahRegionIterator() : 2770 _heap(ShenandoahHeap::heap()), 2771 _index(0) {} 2772 2773 ShenandoahRegionIterator::ShenandoahRegionIterator(ShenandoahHeap* heap) : 2774 _heap(heap), 2775 _index(0) {} 2776 2777 void ShenandoahRegionIterator::reset() { 2778 _index = 0; 2779 } 2780 2781 bool ShenandoahRegionIterator::has_next() const { 2782 return _index < _heap->num_regions(); 2783 } 2784 2785 char ShenandoahHeap::gc_state() const { 2786 return _gc_state.raw_value(); 2787 } 2788 2789 void ShenandoahHeap::deduplicate_string(oop str) { 2790 assert(java_lang_String::is_instance(str), "invariant"); 2791 2792 if (ShenandoahStringDedup::is_enabled()) { 2793 ShenandoahStringDedup::deduplicate(str); 2794 } 2795 } 2796 2797 const char* ShenandoahHeap::init_mark_event_message() const { 2798 bool update_refs = has_forwarded_objects(); 2799 bool proc_refs = process_references(); 2800 bool unload_cls = unload_classes(); 2801 2802 if (update_refs && proc_refs && unload_cls) { 2803 return "Pause Init Mark (update refs) (process weakrefs) (unload classes)"; 2804 } else if (update_refs && proc_refs) { 2805 return "Pause Init Mark (update refs) (process weakrefs)"; 2806 } else if (update_refs && unload_cls) { 2807 return "Pause Init Mark (update refs) (unload classes)"; 2808 } else if (proc_refs && unload_cls) { 2809 return "Pause Init Mark (process weakrefs) (unload classes)"; 2810 } else if (update_refs) { 2811 return "Pause Init Mark (update refs)"; 2812 } else if (proc_refs) { 2813 return "Pause Init Mark (process weakrefs)"; 2814 } else if (unload_cls) { 2815 return "Pause Init Mark (unload classes)"; 2816 } else { 2817 return "Pause Init Mark"; 2818 } 2819 } 2820 2821 const char* ShenandoahHeap::final_mark_event_message() const { 2822 bool update_refs = has_forwarded_objects(); 2823 bool proc_refs = process_references(); 2824 bool unload_cls = unload_classes(); 2825 2826 if (update_refs && proc_refs && unload_cls) { 2827 return "Pause Final Mark (update refs) (process weakrefs) (unload classes)"; 2828 } else if (update_refs && proc_refs) { 2829 return "Pause Final Mark (update refs) (process weakrefs)"; 2830 } else if (update_refs && unload_cls) { 2831 return "Pause Final Mark (update refs) (unload classes)"; 2832 } else if (proc_refs && unload_cls) { 2833 return "Pause Final Mark (process weakrefs) (unload classes)"; 2834 } else if (update_refs) { 2835 return "Pause Final Mark (update refs)"; 2836 } else if (proc_refs) { 2837 return "Pause Final Mark (process weakrefs)"; 2838 } else if (unload_cls) { 2839 return "Pause Final Mark (unload classes)"; 2840 } else { 2841 return "Pause Final Mark"; 2842 } 2843 } 2844 2845 const char* ShenandoahHeap::conc_mark_event_message() const { 2846 bool update_refs = has_forwarded_objects(); 2847 bool proc_refs = process_references(); 2848 bool unload_cls = unload_classes(); 2849 2850 if (update_refs && proc_refs && unload_cls) { 2851 return "Concurrent marking (update refs) (process weakrefs) (unload classes)"; 2852 } else if (update_refs && proc_refs) { 2853 return "Concurrent marking (update refs) (process weakrefs)"; 2854 } else if (update_refs && unload_cls) { 2855 return "Concurrent marking (update refs) (unload classes)"; 2856 } else if (proc_refs && unload_cls) { 2857 return "Concurrent marking (process weakrefs) (unload classes)"; 2858 } else if (update_refs) { 2859 return "Concurrent marking (update refs)"; 2860 } else if (proc_refs) { 2861 return "Concurrent marking (process weakrefs)"; 2862 } else if (unload_cls) { 2863 return "Concurrent marking (unload classes)"; 2864 } else { 2865 return "Concurrent marking"; 2866 } 2867 } 2868 2869 const char* ShenandoahHeap::degen_event_message(ShenandoahDegenPoint point) const { 2870 switch (point) { 2871 case _degenerated_unset: 2872 return "Pause Degenerated GC (<UNSET>)"; 2873 case _degenerated_traversal: 2874 return "Pause Degenerated GC (Traversal)"; 2875 case _degenerated_outside_cycle: 2876 return "Pause Degenerated GC (Outside of Cycle)"; 2877 case _degenerated_mark: 2878 return "Pause Degenerated GC (Mark)"; 2879 case _degenerated_evac: 2880 return "Pause Degenerated GC (Evacuation)"; 2881 case _degenerated_updaterefs: 2882 return "Pause Degenerated GC (Update Refs)"; 2883 default: 2884 ShouldNotReachHere(); 2885 return "ERROR"; 2886 } 2887 } 2888 2889 jushort* ShenandoahHeap::get_liveness_cache(uint worker_id) { 2890 #ifdef ASSERT 2891 assert(_liveness_cache != NULL, "sanity"); 2892 assert(worker_id < _max_workers, "sanity"); 2893 for (uint i = 0; i < num_regions(); i++) { 2894 assert(_liveness_cache[worker_id][i] == 0, "liveness cache should be empty"); 2895 } 2896 #endif 2897 return _liveness_cache[worker_id]; 2898 } 2899 2900 void ShenandoahHeap::flush_liveness_cache(uint worker_id) { 2901 assert(worker_id < _max_workers, "sanity"); 2902 assert(_liveness_cache != NULL, "sanity"); 2903 jushort* ld = _liveness_cache[worker_id]; 2904 for (uint i = 0; i < num_regions(); i++) { 2905 ShenandoahHeapRegion* r = get_region(i); 2906 jushort live = ld[i]; 2907 if (live > 0) { 2908 r->increase_live_data_gc_words(live); 2909 ld[i] = 0; 2910 } 2911 } 2912 }