1 /* 2 * Copyright (c) 2013, 2018, 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 27 #include "gc_implementation/shared/gcTimer.hpp" 28 #include "gc_implementation/shenandoah/shenandoahGCTraceTime.hpp" 29 30 #include "gc_implementation/shenandoah/shenandoahBarrierSet.hpp" 31 #include "gc_implementation/shenandoah/shenandoahClosures.inline.hpp" 32 #include "gc_implementation/shenandoah/shenandoahCollectionSet.hpp" 33 #include "gc_implementation/shenandoah/shenandoahCollectorPolicy.hpp" 34 #include "gc_implementation/shenandoah/shenandoahConcurrentMark.inline.hpp" 35 #include "gc_implementation/shenandoah/shenandoahControlThread.hpp" 36 #include "gc_implementation/shenandoah/shenandoahFreeSet.hpp" 37 #include "gc_implementation/shenandoah/shenandoahPhaseTimings.hpp" 38 #include "gc_implementation/shenandoah/shenandoahHeap.inline.hpp" 39 #include "gc_implementation/shenandoah/shenandoahHeapRegion.inline.hpp" 40 #include "gc_implementation/shenandoah/shenandoahHeapRegionSet.hpp" 41 #include "gc_implementation/shenandoah/shenandoahMarkCompact.hpp" 42 #include "gc_implementation/shenandoah/shenandoahMarkingContext.inline.hpp" 43 #include "gc_implementation/shenandoah/shenandoahMonitoringSupport.hpp" 44 #include "gc_implementation/shenandoah/shenandoahMetrics.hpp" 45 #include "gc_implementation/shenandoah/shenandoahOopClosures.inline.hpp" 46 #include "gc_implementation/shenandoah/shenandoahPacer.inline.hpp" 47 #include "gc_implementation/shenandoah/shenandoahPadding.hpp" 48 #include "gc_implementation/shenandoah/shenandoahParallelCleaning.hpp" 49 #include "gc_implementation/shenandoah/shenandoahRootProcessor.inline.hpp" 50 #include "gc_implementation/shenandoah/shenandoahTaskqueue.hpp" 51 #include "gc_implementation/shenandoah/shenandoahUtils.hpp" 52 #include "gc_implementation/shenandoah/shenandoahVerifier.hpp" 53 #include "gc_implementation/shenandoah/shenandoahCodeRoots.hpp" 54 #include "gc_implementation/shenandoah/shenandoahVMOperations.hpp" 55 #include "gc_implementation/shenandoah/shenandoahWorkGroup.hpp" 56 #include "gc_implementation/shenandoah/shenandoahWorkerPolicy.hpp" 57 #include "gc_implementation/shenandoah/heuristics/shenandoahHeuristics.hpp" 58 #include "gc_implementation/shenandoah/mode/shenandoahIUMode.hpp" 59 #include "gc_implementation/shenandoah/mode/shenandoahPassiveMode.hpp" 60 #include "gc_implementation/shenandoah/mode/shenandoahSATBMode.hpp" 61 #if INCLUDE_JFR 62 #include "gc_implementation/shenandoah/shenandoahJfrSupport.hpp" 63 #endif 64 65 #include "memory/metaspace.hpp" 66 #include "runtime/vmThread.hpp" 67 #include "services/mallocTracker.hpp" 68 69 ShenandoahHeap* ShenandoahHeap::_heap = NULL; 70 71 class ShenandoahPretouchHeapTask : public AbstractGangTask { 72 private: 73 ShenandoahRegionIterator _regions; 74 const size_t _page_size; 75 public: 76 ShenandoahPretouchHeapTask(size_t page_size) : 77 AbstractGangTask("Shenandoah Pretouch Heap"), 78 _page_size(page_size) {} 79 80 virtual void work(uint worker_id) { 81 ShenandoahHeapRegion* r = _regions.next(); 82 while (r != NULL) { 83 if (r->is_committed()) { 84 os::pretouch_memory((char *) r->bottom(), (char *) r->end()); 85 } 86 r = _regions.next(); 87 } 88 } 89 }; 90 91 class ShenandoahPretouchBitmapTask : public AbstractGangTask { 92 private: 93 ShenandoahRegionIterator _regions; 94 char* _bitmap_base; 95 const size_t _bitmap_size; 96 const size_t _page_size; 97 public: 98 ShenandoahPretouchBitmapTask(char* bitmap_base, size_t bitmap_size, size_t page_size) : 99 AbstractGangTask("Shenandoah Pretouch Bitmap"), 100 _bitmap_base(bitmap_base), 101 _bitmap_size(bitmap_size), 102 _page_size(page_size) {} 103 104 virtual void work(uint worker_id) { 105 ShenandoahHeapRegion* r = _regions.next(); 106 while (r != NULL) { 107 size_t start = r->index() * ShenandoahHeapRegion::region_size_bytes() / MarkBitMap::heap_map_factor(); 108 size_t end = (r->index() + 1) * ShenandoahHeapRegion::region_size_bytes() / MarkBitMap::heap_map_factor(); 109 assert (end <= _bitmap_size, err_msg("end is sane: " SIZE_FORMAT " < " SIZE_FORMAT, end, _bitmap_size)); 110 111 if (r->is_committed()) { 112 os::pretouch_memory(_bitmap_base + start, _bitmap_base + end); 113 } 114 115 r = _regions.next(); 116 } 117 } 118 }; 119 120 jint ShenandoahHeap::initialize() { 121 CollectedHeap::pre_initialize(); 122 123 // 124 // Figure out heap sizing 125 // 126 127 size_t init_byte_size = collector_policy()->initial_heap_byte_size(); 128 size_t min_byte_size = collector_policy()->min_heap_byte_size(); 129 size_t max_byte_size = collector_policy()->max_heap_byte_size(); 130 size_t heap_alignment = collector_policy()->heap_alignment(); 131 132 size_t reg_size_bytes = ShenandoahHeapRegion::region_size_bytes(); 133 134 Universe::check_alignment(max_byte_size, reg_size_bytes, "Shenandoah heap"); 135 Universe::check_alignment(init_byte_size, reg_size_bytes, "Shenandoah heap"); 136 137 _num_regions = ShenandoahHeapRegion::region_count(); 138 assert(_num_regions == (max_byte_size / reg_size_bytes), 139 err_msg("Regions should cover entire heap exactly: " SIZE_FORMAT " != " SIZE_FORMAT "/" SIZE_FORMAT, 140 _num_regions, max_byte_size, reg_size_bytes)); 141 // Now we know the number of regions, initialize the heuristics. 142 initialize_heuristics(); 143 144 size_t num_committed_regions = init_byte_size / reg_size_bytes; 145 num_committed_regions = MIN2(num_committed_regions, _num_regions); 146 assert(num_committed_regions <= _num_regions, "sanity"); 147 _initial_size = num_committed_regions * reg_size_bytes; 148 149 size_t num_min_regions = min_byte_size / reg_size_bytes; 150 num_min_regions = MIN2(num_min_regions, _num_regions); 151 assert(num_min_regions <= _num_regions, "sanity"); 152 _minimum_size = num_min_regions * reg_size_bytes; 153 154 // Default to max heap size. 155 _soft_max_size = _num_regions * reg_size_bytes; 156 157 _committed = _initial_size; 158 159 size_t heap_page_size = UseLargePages ? (size_t)os::large_page_size() : (size_t)os::vm_page_size(); 160 size_t bitmap_page_size = UseLargePages ? (size_t)os::large_page_size() : (size_t)os::vm_page_size(); 161 size_t region_page_size = UseLargePages ? (size_t)os::large_page_size() : (size_t)os::vm_page_size(); 162 163 // 164 // Reserve and commit memory for heap 165 // 166 167 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size, heap_alignment); 168 _reserved.set_word_size(0); 169 _reserved.set_start((HeapWord*)heap_rs.base()); 170 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size())); 171 _heap_region = MemRegion((HeapWord*)heap_rs.base(), heap_rs.size() / HeapWordSize); 172 _heap_region_special = heap_rs.special(); 173 174 assert((((size_t) base()) & ShenandoahHeapRegion::region_size_bytes_mask()) == 0, 175 err_msg("Misaligned heap: " PTR_FORMAT, p2i(base()))); 176 177 #if SHENANDOAH_OPTIMIZED_MARKTASK 178 // The optimized ObjArrayChunkedTask takes some bits away from the full object bits. 179 // Fail if we ever attempt to address more than we can. 180 if ((uintptr_t)(heap_rs.base() + heap_rs.size()) >= ShenandoahMarkTask::max_addressable()) { 181 FormatBuffer<512> buf("Shenandoah reserved [" PTR_FORMAT ", " PTR_FORMAT") for the heap, \n" 182 "but max object address is " PTR_FORMAT ". Try to reduce heap size, or try other \n" 183 "VM options that allocate heap at lower addresses (HeapBaseMinAddress, AllocateHeapAt, etc).", 184 p2i(heap_rs.base()), p2i(heap_rs.base() + heap_rs.size()), ShenandoahMarkTask::max_addressable()); 185 vm_exit_during_initialization("Fatal Error", buf); 186 } 187 #endif 188 189 ReservedSpace sh_rs = heap_rs.first_part(max_byte_size); 190 if (!_heap_region_special) { 191 os::commit_memory_or_exit(sh_rs.base(), _initial_size, heap_alignment, false, 192 "Cannot commit heap memory"); 193 } 194 195 // 196 // Reserve and commit memory for bitmap(s) 197 // 198 199 _bitmap_size = MarkBitMap::compute_size(heap_rs.size()); 200 _bitmap_size = align_size_up(_bitmap_size, bitmap_page_size); 201 202 size_t bitmap_bytes_per_region = reg_size_bytes / MarkBitMap::heap_map_factor(); 203 204 guarantee(bitmap_bytes_per_region != 0, 205 err_msg("Bitmap bytes per region should not be zero")); 206 guarantee(is_power_of_2(bitmap_bytes_per_region), 207 err_msg("Bitmap bytes per region should be power of two: " SIZE_FORMAT, bitmap_bytes_per_region)); 208 209 if (bitmap_page_size > bitmap_bytes_per_region) { 210 _bitmap_regions_per_slice = bitmap_page_size / bitmap_bytes_per_region; 211 _bitmap_bytes_per_slice = bitmap_page_size; 212 } else { 213 _bitmap_regions_per_slice = 1; 214 _bitmap_bytes_per_slice = bitmap_bytes_per_region; 215 } 216 217 guarantee(_bitmap_regions_per_slice >= 1, 218 err_msg("Should have at least one region per slice: " SIZE_FORMAT, 219 _bitmap_regions_per_slice)); 220 221 guarantee(((_bitmap_bytes_per_slice) % bitmap_page_size) == 0, 222 err_msg("Bitmap slices should be page-granular: bps = " SIZE_FORMAT ", page size = " SIZE_FORMAT, 223 _bitmap_bytes_per_slice, bitmap_page_size)); 224 225 ReservedSpace bitmap(_bitmap_size, bitmap_page_size); 226 MemTracker::record_virtual_memory_type(bitmap.base(), mtGC); 227 _bitmap_region = MemRegion((HeapWord*) bitmap.base(), bitmap.size() / HeapWordSize); 228 _bitmap_region_special = bitmap.special(); 229 230 size_t bitmap_init_commit = _bitmap_bytes_per_slice * 231 align_size_up(num_committed_regions, _bitmap_regions_per_slice) / _bitmap_regions_per_slice; 232 bitmap_init_commit = MIN2(_bitmap_size, bitmap_init_commit); 233 if (!_bitmap_region_special) { 234 os::commit_memory_or_exit((char *) _bitmap_region.start(), bitmap_init_commit, bitmap_page_size, false, 235 "Cannot commit bitmap memory"); 236 } 237 238 _marking_context = new ShenandoahMarkingContext(_heap_region, _bitmap_region, _num_regions); 239 240 if (ShenandoahVerify) { 241 ReservedSpace verify_bitmap(_bitmap_size, bitmap_page_size); 242 if (!verify_bitmap.special()) { 243 os::commit_memory_or_exit(verify_bitmap.base(), verify_bitmap.size(), bitmap_page_size, false, 244 "Cannot commit verification bitmap memory"); 245 } 246 MemTracker::record_virtual_memory_type(verify_bitmap.base(), mtGC); 247 MemRegion verify_bitmap_region = MemRegion((HeapWord *) verify_bitmap.base(), verify_bitmap.size() / HeapWordSize); 248 _verification_bit_map.initialize(_heap_region, verify_bitmap_region); 249 _verifier = new ShenandoahVerifier(this, &_verification_bit_map); 250 } 251 252 // Reserve aux bitmap for use in object_iterate(). We don't commit it here. 253 ReservedSpace aux_bitmap(_bitmap_size, bitmap_page_size); 254 MemTracker::record_virtual_memory_type(aux_bitmap.base(), mtGC); 255 _aux_bitmap_region = MemRegion((HeapWord*) aux_bitmap.base(), aux_bitmap.size() / HeapWordSize); 256 _aux_bitmap_region_special = aux_bitmap.special(); 257 _aux_bit_map.initialize(_heap_region, _aux_bitmap_region); 258 259 // 260 // Create regions and region sets 261 // 262 size_t region_align = align_size_up(sizeof(ShenandoahHeapRegion), SHENANDOAH_CACHE_LINE_SIZE); 263 size_t region_storage_size = align_size_up(region_align * _num_regions, region_page_size); 264 region_storage_size = align_size_up(region_storage_size, os::vm_allocation_granularity()); 265 266 ReservedSpace region_storage(region_storage_size, region_page_size); 267 MemTracker::record_virtual_memory_type(region_storage.base(), mtGC); 268 if (!region_storage.special()) { 269 os::commit_memory_or_exit(region_storage.base(), region_storage_size, region_page_size, false, 270 "Cannot commit region memory"); 271 } 272 273 // Try to fit the collection set bitmap at lower addresses. This optimizes code generation for cset checks. 274 // Go up until a sensible limit (subject to encoding constraints) and try to reserve the space there. 275 // If not successful, bite a bullet and allocate at whatever address. 276 { 277 size_t cset_align = MAX2<size_t>(os::vm_page_size(), os::vm_allocation_granularity()); 278 size_t cset_size = align_size_up(((size_t) sh_rs.base() + sh_rs.size()) >> ShenandoahHeapRegion::region_size_bytes_shift(), cset_align); 279 280 uintptr_t min = ShenandoahUtils::round_up_power_of_2(cset_align); 281 uintptr_t max = (1u << 30u); 282 283 for (uintptr_t addr = min; addr <= max; addr <<= 1u) { 284 char* req_addr = (char*)addr; 285 assert(is_ptr_aligned(req_addr, cset_align), "Should be aligned"); 286 ReservedSpace cset_rs(cset_size, cset_align, false, req_addr); 287 if (cset_rs.is_reserved()) { 288 assert(cset_rs.base() == req_addr, err_msg("Allocated where requested: " PTR_FORMAT ", " PTR_FORMAT, p2i(cset_rs.base()), addr)); 289 _collection_set = new ShenandoahCollectionSet(this, cset_rs, sh_rs.base()); 290 break; 291 } 292 } 293 294 if (_collection_set == NULL) { 295 ReservedSpace cset_rs(cset_size, cset_align, false); 296 _collection_set = new ShenandoahCollectionSet(this, cset_rs, sh_rs.base()); 297 } 298 } 299 300 _regions = NEW_C_HEAP_ARRAY(ShenandoahHeapRegion*, _num_regions, mtGC); 301 _free_set = new ShenandoahFreeSet(this, _num_regions); 302 303 { 304 ShenandoahHeapLocker locker(lock()); 305 306 for (size_t i = 0; i < _num_regions; i++) { 307 HeapWord* start = (HeapWord*)sh_rs.base() + ShenandoahHeapRegion::region_size_words() * i; 308 bool is_committed = i < num_committed_regions; 309 void* loc = region_storage.base() + i * region_align; 310 311 ShenandoahHeapRegion* r = new (loc) ShenandoahHeapRegion(start, i, is_committed); 312 assert(is_ptr_aligned(r, SHENANDOAH_CACHE_LINE_SIZE), "Sanity"); 313 314 _marking_context->initialize_top_at_mark_start(r); 315 _regions[i] = r; 316 assert(!collection_set()->is_in(i), "New region should not be in collection set"); 317 } 318 319 // Initialize to complete 320 _marking_context->mark_complete(); 321 322 _free_set->rebuild(); 323 } 324 325 if (AlwaysPreTouch) { 326 // For NUMA, it is important to pre-touch the storage under bitmaps with worker threads, 327 // before initialize() below zeroes it with initializing thread. For any given region, 328 // we touch the region and the corresponding bitmaps from the same thread. 329 ShenandoahPushWorkerScope scope(workers(), _max_workers, false); 330 331 _pretouch_heap_page_size = heap_page_size; 332 _pretouch_bitmap_page_size = bitmap_page_size; 333 334 #ifdef LINUX 335 // UseTransparentHugePages would madvise that backing memory can be coalesced into huge 336 // pages. But, the kernel needs to know that every small page is used, in order to coalesce 337 // them into huge one. Therefore, we need to pretouch with smaller pages. 338 if (UseTransparentHugePages) { 339 _pretouch_heap_page_size = (size_t)os::vm_page_size(); 340 _pretouch_bitmap_page_size = (size_t)os::vm_page_size(); 341 } 342 #endif 343 344 // OS memory managers may want to coalesce back-to-back pages. Make their jobs 345 // simpler by pre-touching continuous spaces (heap and bitmap) separately. 346 347 ShenandoahPretouchBitmapTask bcl(bitmap.base(), _bitmap_size, _pretouch_bitmap_page_size); 348 _workers->run_task(&bcl); 349 350 ShenandoahPretouchHeapTask hcl(_pretouch_heap_page_size); 351 _workers->run_task(&hcl); 352 } 353 354 // 355 // Initialize the rest of GC subsystems 356 // 357 358 set_barrier_set(new ShenandoahBarrierSet(this)); 359 360 _liveness_cache = NEW_C_HEAP_ARRAY(ShenandoahLiveData*, _max_workers, mtGC); 361 for (uint worker = 0; worker < _max_workers; worker++) { 362 _liveness_cache[worker] = NEW_C_HEAP_ARRAY(ShenandoahLiveData, _num_regions, mtGC); 363 Copy::fill_to_bytes(_liveness_cache[worker], _num_regions * sizeof(ShenandoahLiveData)); 364 } 365 366 // The call below uses stuff (the SATB* things) that are in G1, but probably 367 // belong into a shared location. 368 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon, 369 SATB_Q_FL_lock, 370 20 /*G1SATBProcessCompletedThreshold */, 371 Shared_SATB_Q_lock); 372 373 _monitoring_support = new ShenandoahMonitoringSupport(this); 374 _phase_timings = new ShenandoahPhaseTimings(max_workers()); 375 ShenandoahStringDedup::initialize(); 376 ShenandoahCodeRoots::initialize(); 377 378 if (ShenandoahPacing) { 379 _pacer = new ShenandoahPacer(this); 380 _pacer->setup_for_idle(); 381 } else { 382 _pacer = NULL; 383 } 384 385 _control_thread = new ShenandoahControlThread(); 386 387 log_info(gc, init)("Initialize Shenandoah heap: " SIZE_FORMAT "%s initial, " SIZE_FORMAT "%s min, " SIZE_FORMAT "%s max", 388 byte_size_in_proper_unit(_initial_size), proper_unit_for_byte_size(_initial_size), 389 byte_size_in_proper_unit(_minimum_size), proper_unit_for_byte_size(_minimum_size), 390 byte_size_in_proper_unit(max_capacity()), proper_unit_for_byte_size(max_capacity()) 391 ); 392 393 return JNI_OK; 394 } 395 396 #ifdef _MSC_VER 397 #pragma warning( push ) 398 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list 399 #endif 400 401 void ShenandoahHeap::initialize_heuristics() { 402 if (ShenandoahGCMode != NULL) { 403 if (strcmp(ShenandoahGCMode, "satb") == 0) { 404 _gc_mode = new ShenandoahSATBMode(); 405 } else if (strcmp(ShenandoahGCMode, "iu") == 0) { 406 _gc_mode = new ShenandoahIUMode(); 407 } else if (strcmp(ShenandoahGCMode, "passive") == 0) { 408 _gc_mode = new ShenandoahPassiveMode(); 409 } else { 410 vm_exit_during_initialization("Unknown -XX:ShenandoahGCMode option"); 411 } 412 } else { 413 ShouldNotReachHere(); 414 } 415 _gc_mode->initialize_flags(); 416 if (_gc_mode->is_diagnostic() && !UnlockDiagnosticVMOptions) { 417 vm_exit_during_initialization( 418 err_msg("GC mode \"%s\" is diagnostic, and must be enabled via -XX:+UnlockDiagnosticVMOptions.", 419 _gc_mode->name())); 420 } 421 if (_gc_mode->is_experimental() && !UnlockExperimentalVMOptions) { 422 vm_exit_during_initialization( 423 err_msg("GC mode \"%s\" is experimental, and must be enabled via -XX:+UnlockExperimentalVMOptions.", 424 _gc_mode->name())); 425 } 426 log_info(gc, init)("Shenandoah GC mode: %s", 427 _gc_mode->name()); 428 429 _heuristics = _gc_mode->initialize_heuristics(); 430 431 if (_heuristics->is_diagnostic() && !UnlockDiagnosticVMOptions) { 432 vm_exit_during_initialization( 433 err_msg("Heuristics \"%s\" is diagnostic, and must be enabled via -XX:+UnlockDiagnosticVMOptions.", 434 _heuristics->name())); 435 } 436 if (_heuristics->is_experimental() && !UnlockExperimentalVMOptions) { 437 vm_exit_during_initialization( 438 err_msg("Heuristics \"%s\" is experimental, and must be enabled via -XX:+UnlockExperimentalVMOptions.", 439 _heuristics->name())); 440 } 441 log_info(gc, init)("Shenandoah heuristics: %s", 442 _heuristics->name()); 443 } 444 445 ShenandoahHeap::ShenandoahHeap(ShenandoahCollectorPolicy* policy) : 446 SharedHeap(policy), 447 _shenandoah_policy(policy), 448 _heap_region_special(false), 449 _regions(NULL), 450 _free_set(NULL), 451 _collection_set(NULL), 452 _update_refs_iterator(this), 453 _bytes_allocated_since_gc_start(0), 454 _max_workers((uint)MAX2(ConcGCThreads, ParallelGCThreads)), 455 _ref_processor(NULL), 456 _marking_context(NULL), 457 _bitmap_size(0), 458 _bitmap_regions_per_slice(0), 459 _bitmap_bytes_per_slice(0), 460 _bitmap_region_special(false), 461 _aux_bitmap_region_special(false), 462 _liveness_cache(NULL), 463 _aux_bit_map(), 464 _verifier(NULL), 465 _pacer(NULL), 466 _gc_timer(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()), 467 _phase_timings(NULL) 468 { 469 _heap = this; 470 471 log_info(gc, init)("GC threads: " UINTX_FORMAT " parallel, " UINTX_FORMAT " concurrent", ParallelGCThreads, ConcGCThreads); 472 473 _scm = new ShenandoahConcurrentMark(); 474 475 _full_gc = new ShenandoahMarkCompact(); 476 _used = 0; 477 478 _max_workers = MAX2(_max_workers, 1U); 479 480 // SharedHeap did not initialize this for us, and we want our own workgang anyway. 481 assert(SharedHeap::_workers == NULL && _workers == NULL, "Should not be initialized yet"); 482 _workers = new ShenandoahWorkGang("Shenandoah GC Threads", _max_workers, 483 /* are_GC_task_threads */true, 484 /* are_ConcurrentGC_threads */false); 485 if (_workers == NULL) { 486 vm_exit_during_initialization("Failed necessary allocation."); 487 } else { 488 _workers->initialize_workers(); 489 } 490 assert(SharedHeap::_workers == _workers, "Sanity: initialized the correct field"); 491 } 492 493 #ifdef _MSC_VER 494 #pragma warning( pop ) 495 #endif 496 497 class ShenandoahResetBitmapTask : public AbstractGangTask { 498 private: 499 ShenandoahRegionIterator _regions; 500 501 public: 502 ShenandoahResetBitmapTask() : 503 AbstractGangTask("Parallel Reset Bitmap Task") {} 504 505 void work(uint worker_id) { 506 ShenandoahHeapRegion* region = _regions.next(); 507 ShenandoahHeap* heap = ShenandoahHeap::heap(); 508 ShenandoahMarkingContext* const ctx = heap->marking_context(); 509 while (region != NULL) { 510 if (heap->is_bitmap_slice_committed(region)) { 511 ctx->clear_bitmap(region); 512 } 513 region = _regions.next(); 514 } 515 } 516 }; 517 518 void ShenandoahHeap::reset_mark_bitmap() { 519 assert_gc_workers(_workers->active_workers()); 520 mark_incomplete_marking_context(); 521 522 ShenandoahResetBitmapTask task; 523 _workers->run_task(&task); 524 } 525 526 void ShenandoahHeap::print_on(outputStream* st) const { 527 st->print_cr("Shenandoah Heap"); 528 st->print_cr(" " SIZE_FORMAT "%s max, " SIZE_FORMAT "%s soft max, " SIZE_FORMAT "%s committed, " SIZE_FORMAT "%s used", 529 byte_size_in_proper_unit(max_capacity()), proper_unit_for_byte_size(max_capacity()), 530 byte_size_in_proper_unit(soft_max_capacity()), proper_unit_for_byte_size(soft_max_capacity()), 531 byte_size_in_proper_unit(committed()), proper_unit_for_byte_size(committed()), 532 byte_size_in_proper_unit(used()), proper_unit_for_byte_size(used())); 533 st->print_cr(" " SIZE_FORMAT " x " SIZE_FORMAT"%s regions", 534 num_regions(), 535 byte_size_in_proper_unit(ShenandoahHeapRegion::region_size_bytes()), 536 proper_unit_for_byte_size(ShenandoahHeapRegion::region_size_bytes())); 537 538 st->print("Status: "); 539 if (has_forwarded_objects()) st->print("has forwarded objects, "); 540 if (is_concurrent_mark_in_progress()) st->print("marking, "); 541 if (is_evacuation_in_progress()) st->print("evacuating, "); 542 if (is_update_refs_in_progress()) st->print("updating refs, "); 543 if (is_degenerated_gc_in_progress()) st->print("degenerated gc, "); 544 if (is_full_gc_in_progress()) st->print("full gc, "); 545 if (is_full_gc_move_in_progress()) st->print("full gc move, "); 546 547 if (cancelled_gc()) { 548 st->print("cancelled"); 549 } else { 550 st->print("not cancelled"); 551 } 552 st->cr(); 553 554 st->print_cr("Reserved region:"); 555 st->print_cr(" - [" PTR_FORMAT ", " PTR_FORMAT ") ", 556 p2i(reserved_region().start()), 557 p2i(reserved_region().end())); 558 559 ShenandoahCollectionSet* cset = collection_set(); 560 st->print_cr("Collection set:"); 561 if (cset != NULL) { 562 st->print_cr(" - map (vanilla): " PTR_FORMAT, p2i(cset->map_address())); 563 st->print_cr(" - map (biased): " PTR_FORMAT, p2i(cset->biased_map_address())); 564 } else { 565 st->print_cr(" (NULL)"); 566 } 567 568 st->cr(); 569 MetaspaceAux::print_on(st); 570 571 if (Verbose) { 572 print_heap_regions_on(st); 573 } 574 } 575 576 class ShenandoahInitGCLABClosure : public ThreadClosure { 577 public: 578 void do_thread(Thread* thread) { 579 assert(thread == NULL || !thread->is_Java_thread(), "Don't expect JavaThread this early"); 580 if (thread != NULL && thread->is_Worker_thread()) { 581 thread->gclab().initialize(true); 582 } 583 } 584 }; 585 586 void ShenandoahHeap::post_initialize() { 587 if (UseTLAB) { 588 MutexLocker ml(Threads_lock); 589 590 ShenandoahInitGCLABClosure init_gclabs; 591 Threads::threads_do(&init_gclabs); 592 } 593 594 _scm->initialize(_max_workers); 595 _full_gc->initialize(_gc_timer); 596 597 ref_processing_init(); 598 599 _heuristics->initialize(); 600 601 JFR_ONLY(ShenandoahJFRSupport::register_jfr_type_serializers()); 602 } 603 604 size_t ShenandoahHeap::used() const { 605 OrderAccess::acquire(); 606 return (size_t) _used; 607 } 608 609 size_t ShenandoahHeap::committed() const { 610 OrderAccess::acquire(); 611 return _committed; 612 } 613 614 void ShenandoahHeap::increase_committed(size_t bytes) { 615 shenandoah_assert_heaplocked_or_safepoint(); 616 _committed += bytes; 617 } 618 619 void ShenandoahHeap::decrease_committed(size_t bytes) { 620 shenandoah_assert_heaplocked_or_safepoint(); 621 _committed -= bytes; 622 } 623 624 void ShenandoahHeap::increase_used(size_t bytes) { 625 Atomic::add(bytes, &_used); 626 } 627 628 void ShenandoahHeap::set_used(size_t bytes) { 629 OrderAccess::release_store_fence(&_used, bytes); 630 } 631 632 void ShenandoahHeap::decrease_used(size_t bytes) { 633 assert(used() >= bytes, "never decrease heap size by more than we've left"); 634 Atomic::add(-(jlong)bytes, &_used); 635 } 636 637 void ShenandoahHeap::increase_allocated(size_t bytes) { 638 Atomic::add(bytes, &_bytes_allocated_since_gc_start); 639 } 640 641 void ShenandoahHeap::notify_mutator_alloc_words(size_t words, bool waste) { 642 size_t bytes = words * HeapWordSize; 643 if (!waste) { 644 increase_used(bytes); 645 } 646 increase_allocated(bytes); 647 if (ShenandoahPacing) { 648 control_thread()->pacing_notify_alloc(words); 649 if (waste) { 650 pacer()->claim_for_alloc(words, true); 651 } 652 } 653 } 654 655 size_t ShenandoahHeap::capacity() const { 656 return committed(); 657 } 658 659 size_t ShenandoahHeap::max_capacity() const { 660 return _num_regions * ShenandoahHeapRegion::region_size_bytes(); 661 } 662 663 size_t ShenandoahHeap::soft_max_capacity() const { 664 size_t v = OrderAccess::load_acquire((volatile size_t*)&_soft_max_size); 665 assert(min_capacity() <= v && v <= max_capacity(), 666 err_msg("Should be in bounds: " SIZE_FORMAT " <= " SIZE_FORMAT " <= " SIZE_FORMAT, 667 min_capacity(), v, max_capacity())); 668 return v; 669 } 670 671 void ShenandoahHeap::set_soft_max_capacity(size_t v) { 672 assert(min_capacity() <= v && v <= max_capacity(), 673 err_msg("Should be in bounds: " SIZE_FORMAT " <= " SIZE_FORMAT " <= " SIZE_FORMAT, 674 min_capacity(), v, max_capacity())); 675 OrderAccess::release_store_fence(&_soft_max_size, v); 676 } 677 678 size_t ShenandoahHeap::min_capacity() const { 679 return _minimum_size; 680 } 681 682 size_t ShenandoahHeap::initial_capacity() const { 683 return _initial_size; 684 } 685 686 bool ShenandoahHeap::is_in(const void* p) const { 687 HeapWord* heap_base = (HeapWord*) base(); 688 HeapWord* last_region_end = heap_base + ShenandoahHeapRegion::region_size_words() * num_regions(); 689 return p >= heap_base && p < last_region_end; 690 } 691 692 void ShenandoahHeap::op_uncommit(double shrink_before, size_t shrink_until) { 693 assert (ShenandoahUncommit, "should be enabled"); 694 695 // Application allocates from the beginning of the heap, and GC allocates at 696 // the end of it. It is more efficient to uncommit from the end, so that applications 697 // could enjoy the near committed regions. GC allocations are much less frequent, 698 // and therefore can accept the committing costs. 699 700 size_t count = 0; 701 for (size_t i = num_regions(); i > 0; i--) { // care about size_t underflow 702 ShenandoahHeapRegion* r = get_region(i - 1); 703 if (r->is_empty_committed() && (r->empty_time() < shrink_before)) { 704 ShenandoahHeapLocker locker(lock()); 705 if (r->is_empty_committed()) { 706 if (committed() < shrink_until + ShenandoahHeapRegion::region_size_bytes()) { 707 break; 708 } 709 710 r->make_uncommitted(); 711 count++; 712 } 713 } 714 SpinPause(); // allow allocators to take the lock 715 } 716 717 if (count > 0) { 718 _control_thread->notify_heap_changed(); 719 } 720 } 721 722 HeapWord* ShenandoahHeap::allocate_from_gclab_slow(Thread* thread, size_t size) { 723 // Retain tlab and allocate object in shared space if 724 // the amount free in the tlab is too large to discard. 725 if (thread->gclab().free() > thread->gclab().refill_waste_limit()) { 726 thread->gclab().record_slow_allocation(size); 727 return NULL; 728 } 729 730 // Discard gclab and allocate a new one. 731 // To minimize fragmentation, the last GCLAB may be smaller than the rest. 732 size_t new_gclab_size = thread->gclab().compute_size(size); 733 734 thread->gclab().clear_before_allocation(); 735 736 if (new_gclab_size == 0) { 737 return NULL; 738 } 739 740 // Allocated object should fit in new GCLAB, and new_gclab_size should be larger than min 741 size_t min_size = MAX2(size + ThreadLocalAllocBuffer::alignment_reserve(), ThreadLocalAllocBuffer::min_size()); 742 new_gclab_size = MAX2(new_gclab_size, min_size); 743 744 // Allocate a new GCLAB... 745 size_t actual_size = 0; 746 HeapWord* obj = allocate_new_gclab(min_size, new_gclab_size, &actual_size); 747 748 if (obj == NULL) { 749 return NULL; 750 } 751 752 assert (size <= actual_size, "allocation should fit"); 753 754 if (ZeroTLAB) { 755 // ..and clear it. 756 Copy::zero_to_words(obj, actual_size); 757 } else { 758 // ...and zap just allocated object. 759 #ifdef ASSERT 760 // Skip mangling the space corresponding to the object header to 761 // ensure that the returned space is not considered parsable by 762 // any concurrent GC thread. 763 size_t hdr_size = oopDesc::header_size(); 764 Copy::fill_to_words(obj + hdr_size, actual_size - hdr_size, badHeapWordVal); 765 #endif // ASSERT 766 } 767 thread->gclab().fill(obj, obj + size, actual_size); 768 return obj; 769 } 770 771 HeapWord* ShenandoahHeap::allocate_new_tlab(size_t word_size) { 772 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_tlab(word_size); 773 return allocate_memory(req); 774 } 775 776 HeapWord* ShenandoahHeap::allocate_new_gclab(size_t min_size, 777 size_t word_size, 778 size_t* actual_size) { 779 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_gclab(min_size, word_size); 780 HeapWord* res = allocate_memory(req); 781 if (res != NULL) { 782 *actual_size = req.actual_size(); 783 } else { 784 *actual_size = 0; 785 } 786 return res; 787 } 788 789 HeapWord* ShenandoahHeap::allocate_memory(ShenandoahAllocRequest& req) { 790 intptr_t pacer_epoch = 0; 791 bool in_new_region = false; 792 HeapWord* result = NULL; 793 794 if (req.is_mutator_alloc()) { 795 if (ShenandoahPacing) { 796 pacer()->pace_for_alloc(req.size()); 797 pacer_epoch = pacer()->epoch(); 798 } 799 800 if (!ShenandoahAllocFailureALot || !should_inject_alloc_failure()) { 801 result = allocate_memory_under_lock(req, in_new_region); 802 } 803 804 // Allocation failed, block until control thread reacted, then retry allocation. 805 // 806 // It might happen that one of the threads requesting allocation would unblock 807 // way later after GC happened, only to fail the second allocation, because 808 // other threads have already depleted the free storage. In this case, a better 809 // strategy is to try again, as long as GC makes progress. 810 // 811 // Then, we need to make sure the allocation was retried after at least one 812 // Full GC, which means we want to try more than ShenandoahFullGCThreshold times. 813 814 size_t tries = 0; 815 816 while (result == NULL && _progress_last_gc.is_set()) { 817 tries++; 818 control_thread()->handle_alloc_failure(req); 819 result = allocate_memory_under_lock(req, in_new_region); 820 } 821 822 while (result == NULL && tries <= ShenandoahFullGCThreshold) { 823 tries++; 824 control_thread()->handle_alloc_failure(req); 825 result = allocate_memory_under_lock(req, in_new_region); 826 } 827 828 } else { 829 assert(req.is_gc_alloc(), "Can only accept GC allocs here"); 830 result = allocate_memory_under_lock(req, in_new_region); 831 // Do not call handle_alloc_failure() here, because we cannot block. 832 // The allocation failure would be handled by the WB slowpath with handle_alloc_failure_evac(). 833 } 834 835 if (in_new_region) { 836 control_thread()->notify_heap_changed(); 837 } 838 839 if (result != NULL) { 840 size_t requested = req.size(); 841 size_t actual = req.actual_size(); 842 843 assert (req.is_lab_alloc() || (requested == actual), 844 err_msg("Only LAB allocations are elastic: %s, requested = " SIZE_FORMAT ", actual = " SIZE_FORMAT, 845 ShenandoahAllocRequest::alloc_type_to_string(req.type()), requested, actual)); 846 847 if (req.is_mutator_alloc()) { 848 notify_mutator_alloc_words(actual, false); 849 850 // If we requested more than we were granted, give the rest back to pacer. 851 // This only matters if we are in the same pacing epoch: do not try to unpace 852 // over the budget for the other phase. 853 if (ShenandoahPacing && (pacer_epoch > 0) && (requested > actual)) { 854 pacer()->unpace_for_alloc(pacer_epoch, requested - actual); 855 } 856 } else { 857 increase_used(actual*HeapWordSize); 858 } 859 } 860 861 return result; 862 } 863 864 HeapWord* ShenandoahHeap::allocate_memory_under_lock(ShenandoahAllocRequest& req, bool& in_new_region) { 865 ShenandoahHeapLocker locker(lock()); 866 return _free_set->allocate(req, in_new_region); 867 } 868 869 HeapWord* ShenandoahHeap::mem_allocate(size_t size, 870 bool* gc_overhead_limit_was_exceeded) { 871 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_shared(size); 872 return allocate_memory(req); 873 } 874 875 class ShenandoahConcurrentEvacuateRegionObjectClosure : public ObjectClosure { 876 private: 877 ShenandoahHeap* const _heap; 878 Thread* const _thread; 879 public: 880 ShenandoahConcurrentEvacuateRegionObjectClosure(ShenandoahHeap* heap) : 881 _heap(heap), _thread(Thread::current()) {} 882 883 void do_object(oop p) { 884 shenandoah_assert_marked(NULL, p); 885 if (!p->is_forwarded()) { 886 _heap->evacuate_object(p, _thread); 887 } 888 } 889 }; 890 891 class ShenandoahEvacuationTask : public AbstractGangTask { 892 private: 893 ShenandoahHeap* const _sh; 894 ShenandoahCollectionSet* const _cs; 895 bool _concurrent; 896 public: 897 ShenandoahEvacuationTask(ShenandoahHeap* sh, 898 ShenandoahCollectionSet* cs, 899 bool concurrent) : 900 AbstractGangTask("Parallel Evacuation Task"), 901 _sh(sh), 902 _cs(cs), 903 _concurrent(concurrent) 904 {} 905 906 void work(uint worker_id) { 907 ShenandoahEvacOOMScope oom_evac_scope; 908 if (_concurrent) { 909 ShenandoahConcurrentWorkerSession worker_session(worker_id); 910 do_work(); 911 } else { 912 ShenandoahParallelWorkerSession worker_session(worker_id); 913 do_work(); 914 } 915 } 916 917 private: 918 void do_work() { 919 ShenandoahConcurrentEvacuateRegionObjectClosure cl(_sh); 920 ShenandoahHeapRegion* r; 921 while ((r =_cs->claim_next()) != NULL) { 922 assert(r->has_live(), err_msg("Region " SIZE_FORMAT " should have been reclaimed early", r->index())); 923 _sh->marked_object_iterate(r, &cl); 924 925 if (ShenandoahPacing) { 926 _sh->pacer()->report_evac(r->used() >> LogHeapWordSize); 927 } 928 929 if (_sh->cancelled_gc()) { 930 break; 931 } 932 } 933 } 934 }; 935 936 void ShenandoahHeap::trash_cset_regions() { 937 ShenandoahHeapLocker locker(lock()); 938 939 ShenandoahCollectionSet* set = collection_set(); 940 ShenandoahHeapRegion* r; 941 set->clear_current_index(); 942 while ((r = set->next()) != NULL) { 943 r->make_trash(); 944 } 945 collection_set()->clear(); 946 } 947 948 void ShenandoahHeap::print_heap_regions_on(outputStream* st) const { 949 st->print_cr("Heap Regions:"); 950 st->print_cr("EU=empty-uncommitted, EC=empty-committed, R=regular, H=humongous start, HC=humongous continuation, CS=collection set, T=trash, P=pinned"); 951 st->print_cr("BTE=bottom/top/end, U=used, T=TLAB allocs, G=GCLAB allocs, S=shared allocs, L=live data"); 952 st->print_cr("R=root, CP=critical pins, TAMS=top-at-mark-start, UWM=update watermark"); 953 st->print_cr("SN=alloc sequence number"); 954 955 for (size_t i = 0; i < num_regions(); i++) { 956 get_region(i)->print_on(st); 957 } 958 } 959 960 void ShenandoahHeap::trash_humongous_region_at(ShenandoahHeapRegion* start) { 961 assert(start->is_humongous_start(), "reclaim regions starting with the first one"); 962 963 oop humongous_obj = oop(start->bottom()); 964 size_t size = humongous_obj->size(); 965 size_t required_regions = ShenandoahHeapRegion::required_regions(size * HeapWordSize); 966 size_t index = start->index() + required_regions - 1; 967 968 assert(!start->has_live(), "liveness must be zero"); 969 970 for(size_t i = 0; i < required_regions; i++) { 971 // Reclaim from tail. Otherwise, assertion fails when printing region to trace log, 972 // as it expects that every region belongs to a humongous region starting with a humongous start region. 973 ShenandoahHeapRegion* region = get_region(index --); 974 975 assert(region->is_humongous(), "expect correct humongous start or continuation"); 976 assert(!region->is_cset(), "Humongous region should not be in collection set"); 977 978 region->make_trash_immediate(); 979 } 980 } 981 982 class ShenandoahRetireGCLABClosure : public ThreadClosure { 983 private: 984 bool _retire; 985 public: 986 ShenandoahRetireGCLABClosure(bool retire) : _retire(retire) {}; 987 988 void do_thread(Thread* thread) { 989 assert(thread->gclab().is_initialized(), err_msg("GCLAB should be initialized for %s", thread->name())); 990 thread->gclab().make_parsable(_retire); 991 } 992 }; 993 994 void ShenandoahHeap::make_parsable(bool retire_tlabs) { 995 if (UseTLAB) { 996 CollectedHeap::ensure_parsability(retire_tlabs); 997 ShenandoahRetireGCLABClosure cl(retire_tlabs); 998 Threads::java_threads_do(&cl); 999 _workers->threads_do(&cl); 1000 } 1001 } 1002 1003 class ShenandoahEvacuateUpdateRootsTask : public AbstractGangTask { 1004 private: 1005 ShenandoahRootEvacuator* _rp; 1006 1007 public: 1008 ShenandoahEvacuateUpdateRootsTask(ShenandoahRootEvacuator* rp) : 1009 AbstractGangTask("Shenandoah evacuate and update roots"), 1010 _rp(rp) {} 1011 1012 void work(uint worker_id) { 1013 ShenandoahParallelWorkerSession worker_session(worker_id); 1014 ShenandoahEvacOOMScope oom_evac_scope; 1015 ShenandoahEvacuateUpdateRootsClosure cl; 1016 1017 MarkingCodeBlobClosure blobsCl(&cl, CodeBlobToOopClosure::FixRelocations); 1018 _rp->roots_do(worker_id, &cl); 1019 } 1020 }; 1021 1022 void ShenandoahHeap::evacuate_and_update_roots() { 1023 COMPILER2_PRESENT(DerivedPointerTable::clear()); 1024 1025 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Only iterate roots while world is stopped"); 1026 1027 { 1028 ShenandoahRootEvacuator rp(ShenandoahPhaseTimings::init_evac); 1029 ShenandoahEvacuateUpdateRootsTask roots_task(&rp); 1030 workers()->run_task(&roots_task); 1031 } 1032 1033 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 1034 } 1035 1036 size_t ShenandoahHeap::unsafe_max_tlab_alloc(Thread *thread) const { 1037 // Returns size in bytes 1038 return MIN2(_free_set->unsafe_peek_free(), ShenandoahHeapRegion::max_tlab_size_bytes()); 1039 } 1040 1041 size_t ShenandoahHeap::max_tlab_size() const { 1042 // Returns size in words 1043 return ShenandoahHeapRegion::max_tlab_size_words(); 1044 } 1045 1046 class ShenandoahResizeGCLABClosure : public ThreadClosure { 1047 public: 1048 void do_thread(Thread* thread) { 1049 assert(thread->gclab().is_initialized(), err_msg("GCLAB should be initialized for %s", thread->name())); 1050 thread->gclab().resize(); 1051 } 1052 }; 1053 1054 void ShenandoahHeap::resize_all_tlabs() { 1055 CollectedHeap::resize_all_tlabs(); 1056 1057 ShenandoahResizeGCLABClosure cl; 1058 Threads::java_threads_do(&cl); 1059 _workers->threads_do(&cl); 1060 } 1061 1062 class ShenandoahAccumulateStatisticsGCLABClosure : public ThreadClosure { 1063 public: 1064 void do_thread(Thread* thread) { 1065 assert(thread->gclab().is_initialized(), err_msg("GCLAB should be initialized for %s", thread->name())); 1066 thread->gclab().accumulate_statistics(); 1067 thread->gclab().initialize_statistics(); 1068 } 1069 }; 1070 1071 void ShenandoahHeap::accumulate_statistics_all_gclabs() { 1072 ShenandoahAccumulateStatisticsGCLABClosure cl; 1073 Threads::java_threads_do(&cl); 1074 _workers->threads_do(&cl); 1075 } 1076 1077 void ShenandoahHeap::collect(GCCause::Cause cause) { 1078 _control_thread->request_gc(cause); 1079 } 1080 1081 void ShenandoahHeap::do_full_collection(bool clear_all_soft_refs) { 1082 //assert(false, "Shouldn't need to do full collections"); 1083 } 1084 1085 CollectorPolicy* ShenandoahHeap::collector_policy() const { 1086 return _shenandoah_policy; 1087 } 1088 1089 void ShenandoahHeap::resize_tlabs() { 1090 CollectedHeap::resize_all_tlabs(); 1091 } 1092 1093 void ShenandoahHeap::accumulate_statistics_tlabs() { 1094 CollectedHeap::accumulate_statistics_all_tlabs(); 1095 } 1096 1097 HeapWord* ShenandoahHeap::block_start(const void* addr) const { 1098 ShenandoahHeapRegion* r = heap_region_containing(addr); 1099 if (r != NULL) { 1100 return r->block_start(addr); 1101 } 1102 return NULL; 1103 } 1104 1105 size_t ShenandoahHeap::block_size(const HeapWord* addr) const { 1106 ShenandoahHeapRegion* r = heap_region_containing(addr); 1107 return r->block_size(addr); 1108 } 1109 1110 bool ShenandoahHeap::block_is_obj(const HeapWord* addr) const { 1111 ShenandoahHeapRegion* r = heap_region_containing(addr); 1112 return r->block_is_obj(addr); 1113 } 1114 1115 jlong ShenandoahHeap::millis_since_last_gc() { 1116 double v = heuristics()->time_since_last_gc() * 1000; 1117 assert(0 <= v && v <= max_jlong, err_msg("value should fit: %f", v)); 1118 return (jlong)v; 1119 } 1120 1121 void ShenandoahHeap::prepare_for_verify() { 1122 if (SafepointSynchronize::is_at_safepoint()) { 1123 make_parsable(false); 1124 } 1125 } 1126 1127 void ShenandoahHeap::print_gc_threads_on(outputStream* st) const { 1128 workers()->print_worker_threads_on(st); 1129 if (ShenandoahStringDedup::is_enabled()) { 1130 ShenandoahStringDedup::print_worker_threads_on(st); 1131 } 1132 } 1133 1134 void ShenandoahHeap::gc_threads_do(ThreadClosure* tcl) const { 1135 workers()->threads_do(tcl); 1136 if (ShenandoahStringDedup::is_enabled()) { 1137 ShenandoahStringDedup::threads_do(tcl); 1138 } 1139 } 1140 1141 void ShenandoahHeap::print_tracing_info() const { 1142 if (PrintGC || TraceGen0Time || TraceGen1Time) { 1143 ResourceMark rm; 1144 outputStream* out = gclog_or_tty; 1145 phase_timings()->print_global_on(out); 1146 1147 out->cr(); 1148 out->cr(); 1149 1150 shenandoah_policy()->print_gc_stats(out); 1151 1152 out->cr(); 1153 out->cr(); 1154 } 1155 } 1156 1157 void ShenandoahHeap::verify(bool silent, VerifyOption vo) { 1158 if (ShenandoahSafepoint::is_at_shenandoah_safepoint() || ! UseTLAB) { 1159 if (ShenandoahVerify) { 1160 verifier()->verify_generic(vo); 1161 } else { 1162 // TODO: Consider allocating verification bitmaps on demand, 1163 // and turn this on unconditionally. 1164 } 1165 } 1166 } 1167 size_t ShenandoahHeap::tlab_capacity(Thread *thr) const { 1168 return _free_set->capacity(); 1169 } 1170 1171 class ObjectIterateScanRootClosure : public ExtendedOopClosure { 1172 private: 1173 MarkBitMap* _bitmap; 1174 Stack<oop,mtGC>* _oop_stack; 1175 1176 template <class T> 1177 void do_oop_work(T* p) { 1178 T o = oopDesc::load_heap_oop(p); 1179 if (!oopDesc::is_null(o)) { 1180 oop obj = oopDesc::decode_heap_oop_not_null(o); 1181 obj = (oop) ShenandoahBarrierSet::resolve_forwarded_not_null(obj); 1182 assert(obj->is_oop(), "must be a valid oop"); 1183 if (!_bitmap->isMarked((HeapWord*) obj)) { 1184 _bitmap->mark((HeapWord*) obj); 1185 _oop_stack->push(obj); 1186 } 1187 } 1188 } 1189 public: 1190 ObjectIterateScanRootClosure(MarkBitMap* bitmap, Stack<oop,mtGC>* oop_stack) : 1191 _bitmap(bitmap), _oop_stack(oop_stack) {} 1192 void do_oop(oop* p) { do_oop_work(p); } 1193 void do_oop(narrowOop* p) { do_oop_work(p); } 1194 }; 1195 1196 /* 1197 * This is public API, used in preparation of object_iterate(). 1198 * Since we don't do linear scan of heap in object_iterate() (see comment below), we don't 1199 * need to make the heap parsable. For Shenandoah-internal linear heap scans that we can 1200 * control, we call SH::make_parsable(). 1201 */ 1202 void ShenandoahHeap::ensure_parsability(bool retire_tlabs) { 1203 // No-op. 1204 } 1205 1206 /* 1207 * Iterates objects in the heap. This is public API, used for, e.g., heap dumping. 1208 * 1209 * We cannot safely iterate objects by doing a linear scan at random points in time. Linear 1210 * scanning needs to deal with dead objects, which may have dead Klass* pointers (e.g. 1211 * calling oopDesc::size() would crash) or dangling reference fields (crashes) etc. Linear 1212 * scanning therefore depends on having a valid marking bitmap to support it. However, we only 1213 * have a valid marking bitmap after successful marking. In particular, we *don't* have a valid 1214 * marking bitmap during marking, after aborted marking or during/after cleanup (when we just 1215 * wiped the bitmap in preparation for next marking). 1216 * 1217 * For all those reasons, we implement object iteration as a single marking traversal, reporting 1218 * objects as we mark+traverse through the heap, starting from GC roots. JVMTI IterateThroughHeap 1219 * is allowed to report dead objects, but is not required to do so. 1220 */ 1221 void ShenandoahHeap::object_iterate(ObjectClosure* cl) { 1222 assert(SafepointSynchronize::is_at_safepoint(), "safe iteration is only available during safepoints"); 1223 if (!_aux_bitmap_region_special && !os::commit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size(), false)) { 1224 log_warning(gc)("Could not commit native memory for auxiliary marking bitmap for heap iteration"); 1225 return; 1226 } 1227 1228 // Reset bitmap 1229 _aux_bit_map.clear(); 1230 1231 Stack<oop,mtGC> oop_stack; 1232 1233 ObjectIterateScanRootClosure oops(&_aux_bit_map, &oop_stack); 1234 1235 { 1236 // First, we process GC roots according to current GC cycle. 1237 // This populates the work stack with initial objects. 1238 // It is important to relinquish the associated locks before diving 1239 // into heap dumper. 1240 ShenandoahHeapIterationRootScanner rp; 1241 rp.roots_do(&oops); 1242 } 1243 1244 // Work through the oop stack to traverse heap. 1245 while (! oop_stack.is_empty()) { 1246 oop obj = oop_stack.pop(); 1247 assert(obj->is_oop(), "must be a valid oop"); 1248 cl->do_object(obj); 1249 obj->oop_iterate(&oops); 1250 } 1251 1252 assert(oop_stack.is_empty(), "should be empty"); 1253 1254 if (!_aux_bitmap_region_special && !os::uncommit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size())) { 1255 log_warning(gc)("Could not uncommit native memory for auxiliary marking bitmap for heap iteration"); 1256 } 1257 } 1258 1259 void ShenandoahHeap::safe_object_iterate(ObjectClosure* cl) { 1260 assert(SafepointSynchronize::is_at_safepoint(), "safe iteration is only available during safepoints"); 1261 object_iterate(cl); 1262 } 1263 1264 void ShenandoahHeap::oop_iterate(ExtendedOopClosure* cl) { 1265 ObjectToOopClosure cl2(cl); 1266 object_iterate(&cl2); 1267 } 1268 1269 void ShenandoahHeap::gc_prologue(bool b) { 1270 Unimplemented(); 1271 } 1272 1273 void ShenandoahHeap::gc_epilogue(bool b) { 1274 Unimplemented(); 1275 } 1276 1277 void ShenandoahHeap::heap_region_iterate(ShenandoahHeapRegionClosure* blk) const { 1278 for (size_t i = 0; i < num_regions(); i++) { 1279 ShenandoahHeapRegion* current = get_region(i); 1280 blk->heap_region_do(current); 1281 } 1282 } 1283 1284 class ShenandoahParallelHeapRegionTask : public AbstractGangTask { 1285 private: 1286 ShenandoahHeap* const _heap; 1287 ShenandoahHeapRegionClosure* const _blk; 1288 1289 shenandoah_padding(0); 1290 volatile jint _index; 1291 shenandoah_padding(1); 1292 1293 public: 1294 ShenandoahParallelHeapRegionTask(ShenandoahHeapRegionClosure* blk) : 1295 AbstractGangTask("Parallel Region Task"), 1296 _heap(ShenandoahHeap::heap()), _blk(blk), _index(0) {} 1297 1298 void work(uint worker_id) { 1299 jint stride = (jint)ShenandoahParallelRegionStride; 1300 1301 jint max = (jint)_heap->num_regions(); 1302 while (_index < max) { 1303 jint cur = Atomic::add(stride, &_index) - stride; 1304 jint start = cur; 1305 jint end = MIN2(cur + stride, max); 1306 if (start >= max) break; 1307 1308 for (jint i = cur; i < end; i++) { 1309 ShenandoahHeapRegion* current = _heap->get_region((size_t)i); 1310 _blk->heap_region_do(current); 1311 } 1312 } 1313 } 1314 }; 1315 1316 void ShenandoahHeap::parallel_heap_region_iterate(ShenandoahHeapRegionClosure* blk) const { 1317 assert(blk->is_thread_safe(), "Only thread-safe closures here"); 1318 if (num_regions() > ShenandoahParallelRegionStride) { 1319 ShenandoahParallelHeapRegionTask task(blk); 1320 workers()->run_task(&task); 1321 } else { 1322 heap_region_iterate(blk); 1323 } 1324 } 1325 1326 class ShenandoahInitMarkUpdateRegionStateClosure : public ShenandoahHeapRegionClosure { 1327 private: 1328 ShenandoahMarkingContext* const _ctx; 1329 public: 1330 ShenandoahInitMarkUpdateRegionStateClosure() : _ctx(ShenandoahHeap::heap()->marking_context()) {} 1331 1332 void heap_region_do(ShenandoahHeapRegion* r) { 1333 assert(!r->has_live(), 1334 err_msg("Region " SIZE_FORMAT " should have no live data", r->index())); 1335 if (r->is_active()) { 1336 // Check if region needs updating its TAMS. We have updated it already during concurrent 1337 // reset, so it is very likely we don't need to do another write here. 1338 if (_ctx->top_at_mark_start(r) != r->top()) { 1339 _ctx->capture_top_at_mark_start(r); 1340 } 1341 } else { 1342 assert(_ctx->top_at_mark_start(r) == r->top(), 1343 err_msg("Region " SIZE_FORMAT " should already have correct TAMS", r->index())); 1344 } 1345 } 1346 1347 bool is_thread_safe() { return true; } 1348 }; 1349 1350 void ShenandoahHeap::op_init_mark() { 1351 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should be at safepoint"); 1352 assert(Thread::current()->is_VM_thread(), "can only do this in VMThread"); 1353 1354 assert(marking_context()->is_bitmap_clear(), "need clear marking bitmap"); 1355 assert(!marking_context()->is_complete(), "should not be complete"); 1356 assert(!has_forwarded_objects(), "No forwarded objects on this path"); 1357 1358 if (ShenandoahVerify) { 1359 verifier()->verify_before_concmark(); 1360 } 1361 1362 { 1363 ShenandoahGCPhase phase(ShenandoahPhaseTimings::accumulate_stats); 1364 accumulate_statistics_tlabs(); 1365 } 1366 1367 if (VerifyBeforeGC) { 1368 Universe::verify(); 1369 } 1370 1371 set_concurrent_mark_in_progress(true); 1372 // We need to reset all TLABs because we'd lose marks on all objects allocated in them. 1373 if (UseTLAB) { 1374 ShenandoahGCPhase phase(ShenandoahPhaseTimings::make_parsable); 1375 make_parsable(true); 1376 } 1377 1378 { 1379 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_region_states); 1380 ShenandoahInitMarkUpdateRegionStateClosure cl; 1381 parallel_heap_region_iterate(&cl); 1382 } 1383 1384 // Make above changes visible to worker threads 1385 OrderAccess::fence(); 1386 1387 concurrent_mark()->mark_roots(ShenandoahPhaseTimings::scan_roots); 1388 1389 if (UseTLAB) { 1390 ShenandoahGCPhase phase(ShenandoahPhaseTimings::resize_tlabs); 1391 resize_tlabs(); 1392 } 1393 1394 if (ShenandoahPacing) { 1395 pacer()->setup_for_mark(); 1396 } 1397 } 1398 1399 void ShenandoahHeap::op_mark() { 1400 concurrent_mark()->mark_from_roots(); 1401 } 1402 1403 class ShenandoahFinalMarkUpdateRegionStateClosure : public ShenandoahHeapRegionClosure { 1404 private: 1405 ShenandoahMarkingContext* const _ctx; 1406 ShenandoahHeapLock* const _lock; 1407 1408 public: 1409 ShenandoahFinalMarkUpdateRegionStateClosure() : 1410 _ctx(ShenandoahHeap::heap()->complete_marking_context()), _lock(ShenandoahHeap::heap()->lock()) {} 1411 1412 void heap_region_do(ShenandoahHeapRegion* r) { 1413 if (r->is_active()) { 1414 // All allocations past TAMS are implicitly live, adjust the region data. 1415 // Bitmaps/TAMS are swapped at this point, so we need to poll complete bitmap. 1416 HeapWord *tams = _ctx->top_at_mark_start(r); 1417 HeapWord *top = r->top(); 1418 if (top > tams) { 1419 r->increase_live_data_alloc_words(pointer_delta(top, tams)); 1420 } 1421 1422 // We are about to select the collection set, make sure it knows about 1423 // current pinning status. Also, this allows trashing more regions that 1424 // now have their pinning status dropped. 1425 if (r->is_pinned()) { 1426 if (r->pin_count() == 0) { 1427 ShenandoahHeapLocker locker(_lock); 1428 r->make_unpinned(); 1429 } 1430 } else { 1431 if (r->pin_count() > 0) { 1432 ShenandoahHeapLocker locker(_lock); 1433 r->make_pinned(); 1434 } 1435 } 1436 1437 // Remember limit for updating refs. It's guaranteed that we get no 1438 // from-space-refs written from here on. 1439 r->set_update_watermark_at_safepoint(r->top()); 1440 } else { 1441 assert(!r->has_live(), 1442 err_msg("Region " SIZE_FORMAT " should have no live data", r->index())); 1443 assert(_ctx->top_at_mark_start(r) == r->top(), 1444 err_msg("Region " SIZE_FORMAT " should have correct TAMS", r->index())); 1445 } 1446 } 1447 1448 bool is_thread_safe() { return true; } 1449 }; 1450 1451 void ShenandoahHeap::op_final_mark() { 1452 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should be at safepoint"); 1453 assert(!has_forwarded_objects(), "No forwarded objects on this path"); 1454 1455 // It is critical that we 1456 // evacuate roots right after finishing marking, so that we don't 1457 // get unmarked objects in the roots. 1458 1459 if (!cancelled_gc()) { 1460 concurrent_mark()->finish_mark_from_roots(/* full_gc = */ false); 1461 1462 TASKQUEUE_STATS_ONLY(concurrent_mark()->task_queues()->reset_taskqueue_stats()); 1463 1464 if (ShenandoahVerify) { 1465 verifier()->verify_roots_no_forwarded(); 1466 } 1467 1468 TASKQUEUE_STATS_ONLY(concurrent_mark()->task_queues()->print_taskqueue_stats()); 1469 1470 { 1471 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_region_states); 1472 ShenandoahFinalMarkUpdateRegionStateClosure cl; 1473 parallel_heap_region_iterate(&cl); 1474 1475 assert_pinned_region_status(); 1476 } 1477 1478 // Force the threads to reacquire their TLABs outside the collection set. 1479 { 1480 ShenandoahGCPhase phase(ShenandoahPhaseTimings::retire_tlabs); 1481 make_parsable(true); 1482 } 1483 1484 { 1485 ShenandoahGCPhase phase(ShenandoahPhaseTimings::choose_cset); 1486 ShenandoahHeapLocker locker(lock()); 1487 _collection_set->clear(); 1488 heuristics()->choose_collection_set(_collection_set); 1489 } 1490 1491 { 1492 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_rebuild_freeset); 1493 ShenandoahHeapLocker locker(lock()); 1494 _free_set->rebuild(); 1495 } 1496 1497 // If collection set has candidates, start evacuation. 1498 // Otherwise, bypass the rest of the cycle. 1499 if (!collection_set()->is_empty()) { 1500 ShenandoahGCPhase init_evac(ShenandoahPhaseTimings::init_evac); 1501 1502 if (ShenandoahVerify) { 1503 verifier()->verify_before_evacuation(); 1504 } 1505 1506 set_evacuation_in_progress(true); 1507 // From here on, we need to update references. 1508 set_has_forwarded_objects(true); 1509 1510 if (!is_degenerated_gc_in_progress()) { 1511 evacuate_and_update_roots(); 1512 } 1513 1514 if (ShenandoahPacing) { 1515 pacer()->setup_for_evac(); 1516 } 1517 1518 if (ShenandoahVerify) { 1519 verifier()->verify_roots_no_forwarded(); 1520 verifier()->verify_during_evacuation(); 1521 } 1522 } else { 1523 if (ShenandoahVerify) { 1524 verifier()->verify_after_concmark(); 1525 } 1526 1527 if (VerifyAfterGC) { 1528 Universe::verify(); 1529 } 1530 } 1531 1532 } else { 1533 concurrent_mark()->cancel(); 1534 complete_marking(); 1535 1536 if (process_references()) { 1537 // Abandon reference processing right away: pre-cleaning must have failed. 1538 ReferenceProcessor *rp = ref_processor(); 1539 rp->disable_discovery(); 1540 rp->abandon_partial_discovery(); 1541 rp->verify_no_references_recorded(); 1542 } 1543 } 1544 } 1545 1546 void ShenandoahHeap::op_conc_evac() { 1547 ShenandoahEvacuationTask task(this, _collection_set, true); 1548 workers()->run_task(&task); 1549 } 1550 1551 void ShenandoahHeap::op_stw_evac() { 1552 ShenandoahEvacuationTask task(this, _collection_set, false); 1553 workers()->run_task(&task); 1554 } 1555 1556 void ShenandoahHeap::op_updaterefs() { 1557 update_heap_references(true); 1558 } 1559 1560 void ShenandoahHeap::op_cleanup_early() { 1561 free_set()->recycle_trash(); 1562 } 1563 1564 void ShenandoahHeap::op_cleanup_complete() { 1565 free_set()->recycle_trash(); 1566 } 1567 1568 class ShenandoahResetUpdateRegionStateClosure : public ShenandoahHeapRegionClosure { 1569 private: 1570 ShenandoahMarkingContext* const _ctx; 1571 public: 1572 ShenandoahResetUpdateRegionStateClosure() : _ctx(ShenandoahHeap::heap()->marking_context()) {} 1573 1574 void heap_region_do(ShenandoahHeapRegion* r) { 1575 if (r->is_active()) { 1576 // Reset live data and set TAMS optimistically. We would recheck these under the pause 1577 // anyway to capture any updates that happened since now. 1578 r->clear_live_data(); 1579 _ctx->capture_top_at_mark_start(r); 1580 } 1581 } 1582 1583 bool is_thread_safe() { return true; } 1584 }; 1585 1586 void ShenandoahHeap::op_reset() { 1587 if (ShenandoahPacing) { 1588 pacer()->setup_for_reset(); 1589 } 1590 reset_mark_bitmap(); 1591 1592 ShenandoahResetUpdateRegionStateClosure cl; 1593 parallel_heap_region_iterate(&cl); 1594 } 1595 1596 void ShenandoahHeap::op_preclean() { 1597 if (ShenandoahPacing) { 1598 pacer()->setup_for_preclean(); 1599 } 1600 concurrent_mark()->preclean_weak_refs(); 1601 } 1602 1603 void ShenandoahHeap::op_full(GCCause::Cause cause) { 1604 ShenandoahMetricsSnapshot metrics; 1605 metrics.snap_before(); 1606 1607 full_gc()->do_it(cause); 1608 1609 metrics.snap_after(); 1610 1611 if (metrics.is_good_progress()) { 1612 _progress_last_gc.set(); 1613 } else { 1614 // Nothing to do. Tell the allocation path that we have failed to make 1615 // progress, and it can finally fail. 1616 _progress_last_gc.unset(); 1617 } 1618 } 1619 1620 void ShenandoahHeap::op_degenerated(ShenandoahDegenPoint point) { 1621 // Degenerated GC is STW, but it can also fail. Current mechanics communicates 1622 // GC failure via cancelled_concgc() flag. So, if we detect the failure after 1623 // some phase, we have to upgrade the Degenerate GC to Full GC. 1624 1625 clear_cancelled_gc(); 1626 1627 ShenandoahMetricsSnapshot metrics; 1628 metrics.snap_before(); 1629 1630 switch (point) { 1631 // The cases below form the Duff's-like device: it describes the actual GC cycle, 1632 // but enters it at different points, depending on which concurrent phase had 1633 // degenerated. 1634 1635 case _degenerated_outside_cycle: 1636 // We have degenerated from outside the cycle, which means something is bad with 1637 // the heap, most probably heavy humongous fragmentation, or we are very low on free 1638 // space. It makes little sense to wait for Full GC to reclaim as much as it can, when 1639 // we can do the most aggressive degen cycle, which includes processing references and 1640 // class unloading, unless those features are explicitly disabled. 1641 // 1642 // Note that we can only do this for "outside-cycle" degens, otherwise we would risk 1643 // changing the cycle parameters mid-cycle during concurrent -> degenerated handover. 1644 set_process_references(heuristics()->can_process_references()); 1645 set_unload_classes(heuristics()->can_unload_classes()); 1646 1647 if (_heap->process_references()) { 1648 ReferenceProcessor* rp = _heap->ref_processor(); 1649 rp->set_active_mt_degree(_heap->workers()->active_workers()); 1650 1651 // enable ("weak") refs discovery 1652 rp->enable_discovery(true /*verify_no_refs*/, true); 1653 rp->setup_policy(_heap->collector_policy()->should_clear_all_soft_refs()); 1654 } 1655 1656 op_reset(); 1657 1658 op_init_mark(); 1659 if (cancelled_gc()) { 1660 op_degenerated_fail(); 1661 return; 1662 } 1663 1664 case _degenerated_mark: 1665 op_final_mark(); 1666 if (cancelled_gc()) { 1667 op_degenerated_fail(); 1668 return; 1669 } 1670 1671 op_cleanup_early(); 1672 1673 case _degenerated_evac: 1674 // If heuristics thinks we should do the cycle, this flag would be set, 1675 // and we can do evacuation. Otherwise, it would be the shortcut cycle. 1676 if (is_evacuation_in_progress()) { 1677 1678 // Degeneration under oom-evac protocol might have left some objects in 1679 // collection set un-evacuated. Restart evacuation from the beginning to 1680 // capture all objects. For all the objects that are already evacuated, 1681 // it would be a simple check, which is supposed to be fast. This is also 1682 // safe to do even without degeneration, as CSet iterator is at beginning 1683 // in preparation for evacuation anyway. 1684 // 1685 // Before doing that, we need to make sure we never had any cset-pinned 1686 // regions. This may happen if allocation failure happened when evacuating 1687 // the about-to-be-pinned object, oom-evac protocol left the object in 1688 // the collection set, and then the pin reached the cset region. If we continue 1689 // the cycle here, we would trash the cset and alive objects in it. To avoid 1690 // it, we fail degeneration right away and slide into Full GC to recover. 1691 1692 { 1693 sync_pinned_region_status(); 1694 collection_set()->clear_current_index(); 1695 1696 ShenandoahHeapRegion* r; 1697 while ((r = collection_set()->next()) != NULL) { 1698 if (r->is_pinned()) { 1699 cancel_gc(GCCause::_shenandoah_upgrade_to_full_gc); 1700 op_degenerated_fail(); 1701 return; 1702 } 1703 } 1704 1705 collection_set()->clear_current_index(); 1706 } 1707 1708 op_stw_evac(); 1709 if (cancelled_gc()) { 1710 op_degenerated_fail(); 1711 return; 1712 } 1713 } 1714 1715 // If heuristics thinks we should do the cycle, this flag would be set, 1716 // and we need to do update-refs. Otherwise, it would be the shortcut cycle. 1717 if (has_forwarded_objects()) { 1718 op_init_updaterefs(); 1719 if (cancelled_gc()) { 1720 op_degenerated_fail(); 1721 return; 1722 } 1723 } 1724 1725 case _degenerated_updaterefs: 1726 if (has_forwarded_objects()) { 1727 op_final_updaterefs(); 1728 if (cancelled_gc()) { 1729 op_degenerated_fail(); 1730 return; 1731 } 1732 } 1733 1734 op_cleanup_complete(); 1735 break; 1736 1737 default: 1738 ShouldNotReachHere(); 1739 } 1740 1741 if (ShenandoahVerify) { 1742 verifier()->verify_after_degenerated(); 1743 } 1744 1745 if (VerifyAfterGC) { 1746 Universe::verify(); 1747 } 1748 1749 metrics.snap_after(); 1750 1751 // Check for futility and fail. There is no reason to do several back-to-back Degenerated cycles, 1752 // because that probably means the heap is overloaded and/or fragmented. 1753 if (!metrics.is_good_progress()) { 1754 _progress_last_gc.unset(); 1755 cancel_gc(GCCause::_shenandoah_upgrade_to_full_gc); 1756 op_degenerated_futile(); 1757 } else { 1758 _progress_last_gc.set(); 1759 } 1760 } 1761 1762 void ShenandoahHeap::op_degenerated_fail() { 1763 log_info(gc)("Cannot finish degeneration, upgrading to Full GC"); 1764 shenandoah_policy()->record_degenerated_upgrade_to_full(); 1765 op_full(GCCause::_shenandoah_upgrade_to_full_gc); 1766 } 1767 1768 void ShenandoahHeap::op_degenerated_futile() { 1769 shenandoah_policy()->record_degenerated_upgrade_to_full(); 1770 op_full(GCCause::_shenandoah_upgrade_to_full_gc); 1771 } 1772 1773 void ShenandoahHeap::complete_marking() { 1774 if (is_concurrent_mark_in_progress()) { 1775 set_concurrent_mark_in_progress(false); 1776 } 1777 1778 if (!cancelled_gc()) { 1779 // If we needed to update refs, and concurrent marking has been cancelled, 1780 // we need to finish updating references. 1781 set_has_forwarded_objects(false); 1782 mark_complete_marking_context(); 1783 } 1784 } 1785 1786 void ShenandoahHeap::force_satb_flush_all_threads() { 1787 if (!is_concurrent_mark_in_progress()) { 1788 // No need to flush SATBs 1789 return; 1790 } 1791 1792 // Do not block if Threads lock is busy. This avoids the potential deadlock 1793 // when this code is called from the periodic task, and something else is 1794 // expecting the periodic task to complete without blocking. On the off-chance 1795 // Threads lock is busy momentarily, try to acquire several times. 1796 for (int t = 0; t < 10; t++) { 1797 if (Threads_lock->try_lock()) { 1798 JavaThread::set_force_satb_flush_all_threads(true); 1799 Threads_lock->unlock(); 1800 1801 // The threads are not "acquiring" their thread-local data, but it does not 1802 // hurt to "release" the updates here anyway. 1803 OrderAccess::fence(); 1804 break; 1805 } 1806 os::naked_short_sleep(1); 1807 } 1808 } 1809 1810 void ShenandoahHeap::set_gc_state_mask(uint mask, bool value) { 1811 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should really be Shenandoah safepoint"); 1812 _gc_state.set_cond(mask, value); 1813 JavaThread::set_gc_state_all_threads(_gc_state.raw_value()); 1814 } 1815 1816 void ShenandoahHeap::set_concurrent_mark_in_progress(bool in_progress) { 1817 if (has_forwarded_objects()) { 1818 set_gc_state_mask(MARKING | UPDATEREFS, in_progress); 1819 } else { 1820 set_gc_state_mask(MARKING, in_progress); 1821 } 1822 JavaThread::satb_mark_queue_set().set_active_all_threads(in_progress, !in_progress); 1823 } 1824 1825 void ShenandoahHeap::set_evacuation_in_progress(bool in_progress) { 1826 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Only call this at safepoint"); 1827 set_gc_state_mask(EVACUATION, in_progress); 1828 } 1829 1830 void ShenandoahHeap::ref_processing_init() { 1831 MemRegion mr = reserved_region(); 1832 1833 assert(_max_workers > 0, "Sanity"); 1834 1835 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1); 1836 bool mt_discovery = _max_workers > 1; 1837 1838 _ref_processor = 1839 new ReferenceProcessor(mr, // span 1840 mt_processing, // MT processing 1841 _max_workers, // Degree of MT processing 1842 mt_discovery, // MT discovery 1843 _max_workers, // Degree of MT discovery 1844 false, // Reference discovery is not atomic 1845 NULL); // No closure, should be installed before use 1846 1847 log_info(gc, init)("Reference processing: %s discovery, %s processing", 1848 mt_discovery ? "parallel" : "serial", 1849 mt_processing ? "parallel" : "serial"); 1850 1851 shenandoah_assert_rp_isalive_not_installed(); 1852 } 1853 1854 void ShenandoahHeap::acquire_pending_refs_lock() { 1855 _control_thread->slt()->manipulatePLL(SurrogateLockerThread::acquirePLL); 1856 } 1857 1858 void ShenandoahHeap::release_pending_refs_lock() { 1859 _control_thread->slt()->manipulatePLL(SurrogateLockerThread::releaseAndNotifyPLL); 1860 } 1861 1862 GCTracer* ShenandoahHeap::tracer() { 1863 return shenandoah_policy()->tracer(); 1864 } 1865 1866 size_t ShenandoahHeap::tlab_used(Thread* thread) const { 1867 return _free_set->used(); 1868 } 1869 1870 void ShenandoahHeap::cancel_gc(GCCause::Cause cause) { 1871 if (try_cancel_gc()) { 1872 FormatBuffer<> msg("Cancelling GC: %s", GCCause::to_string(cause)); 1873 log_info(gc)("%s", msg.buffer()); 1874 Events::log(Thread::current(), "%s", msg.buffer()); 1875 } 1876 } 1877 1878 uint ShenandoahHeap::max_workers() { 1879 return _max_workers; 1880 } 1881 1882 void ShenandoahHeap::stop() { 1883 // The shutdown sequence should be able to terminate when GC is running. 1884 1885 // Step 0. Notify policy to disable event recording. 1886 _shenandoah_policy->record_shutdown(); 1887 1888 // Step 1. Notify control thread that we are in shutdown. 1889 // Note that we cannot do that with stop(), because stop() is blocking and waits for the actual shutdown. 1890 // Doing stop() here would wait for the normal GC cycle to complete, never falling through to cancel below. 1891 _control_thread->prepare_for_graceful_shutdown(); 1892 1893 // Step 2. Notify GC workers that we are cancelling GC. 1894 cancel_gc(GCCause::_shenandoah_stop_vm); 1895 1896 // Step 3. Wait until GC worker exits normally. 1897 _control_thread->stop(); 1898 1899 // Step 4. Stop String Dedup thread if it is active 1900 if (ShenandoahStringDedup::is_enabled()) { 1901 ShenandoahStringDedup::stop(); 1902 } 1903 } 1904 1905 void ShenandoahHeap::unload_classes_and_cleanup_tables(bool full_gc) { 1906 assert(heuristics()->can_unload_classes(), "Class unloading should be enabled"); 1907 1908 ShenandoahGCPhase root_phase(full_gc ? 1909 ShenandoahPhaseTimings::full_gc_purge : 1910 ShenandoahPhaseTimings::purge); 1911 1912 ShenandoahIsAliveSelector alive; 1913 BoolObjectClosure* is_alive = alive.is_alive_closure(); 1914 1915 // Cleaning of klasses depends on correct information from MetadataMarkOnStack. The CodeCache::mark_on_stack 1916 // part is too slow to be done serially, so it is handled during the ShenandoahParallelCleaning phase. 1917 // Defer the cleaning until we have complete on_stack data. 1918 MetadataOnStackMark md_on_stack(false /* Don't visit the code cache at this point */); 1919 1920 bool purged_class; 1921 1922 // Unload classes and purge SystemDictionary. 1923 { 1924 ShenandoahGCPhase phase(full_gc ? 1925 ShenandoahPhaseTimings::full_gc_purge_class_unload : 1926 ShenandoahPhaseTimings::purge_class_unload); 1927 purged_class = SystemDictionary::do_unloading(is_alive, 1928 false /* Defer klass cleaning */); 1929 } 1930 { 1931 ShenandoahGCPhase phase(full_gc ? 1932 ShenandoahPhaseTimings::full_gc_purge_par : 1933 ShenandoahPhaseTimings::purge_par); 1934 uint active = _workers->active_workers(); 1935 ShenandoahParallelCleaningTask unlink_task(is_alive, true, true, active, purged_class); 1936 _workers->run_task(&unlink_task); 1937 } 1938 1939 { 1940 ShenandoahGCPhase phase(full_gc ? 1941 ShenandoahPhaseTimings::full_gc_purge_metadata : 1942 ShenandoahPhaseTimings::purge_metadata); 1943 ClassLoaderDataGraph::free_deallocate_lists(); 1944 } 1945 1946 if (ShenandoahStringDedup::is_enabled()) { 1947 ShenandoahGCPhase phase(full_gc ? 1948 ShenandoahPhaseTimings::full_gc_purge_string_dedup : 1949 ShenandoahPhaseTimings::purge_string_dedup); 1950 ShenandoahStringDedup::parallel_cleanup(); 1951 } 1952 1953 { 1954 ShenandoahGCPhase phase(full_gc ? 1955 ShenandoahPhaseTimings::full_gc_purge_cldg : 1956 ShenandoahPhaseTimings::purge_cldg); 1957 ClassLoaderDataGraph::purge(); 1958 } 1959 } 1960 1961 void ShenandoahHeap::set_has_forwarded_objects(bool cond) { 1962 set_gc_state_mask(HAS_FORWARDED, cond); 1963 } 1964 1965 void ShenandoahHeap::set_process_references(bool pr) { 1966 _process_references.set_cond(pr); 1967 } 1968 1969 void ShenandoahHeap::set_unload_classes(bool uc) { 1970 _unload_classes.set_cond(uc); 1971 } 1972 1973 bool ShenandoahHeap::process_references() const { 1974 return _process_references.is_set(); 1975 } 1976 1977 bool ShenandoahHeap::unload_classes() const { 1978 return _unload_classes.is_set(); 1979 } 1980 1981 address ShenandoahHeap::in_cset_fast_test_addr() { 1982 ShenandoahHeap* heap = ShenandoahHeap::heap(); 1983 assert(heap->collection_set() != NULL, "Sanity"); 1984 return (address) heap->collection_set()->biased_map_address(); 1985 } 1986 1987 address ShenandoahHeap::cancelled_gc_addr() { 1988 return (address) ShenandoahHeap::heap()->_cancelled_gc.addr_of(); 1989 } 1990 1991 address ShenandoahHeap::gc_state_addr() { 1992 return (address) ShenandoahHeap::heap()->_gc_state.addr_of(); 1993 } 1994 1995 size_t ShenandoahHeap::conservative_max_heap_alignment() { 1996 size_t align = ShenandoahMaxRegionSize; 1997 if (UseLargePages) { 1998 align = MAX2(align, os::large_page_size()); 1999 } 2000 return align; 2001 } 2002 2003 size_t ShenandoahHeap::bytes_allocated_since_gc_start() { 2004 return OrderAccess::load_acquire(&_bytes_allocated_since_gc_start); 2005 } 2006 2007 void ShenandoahHeap::reset_bytes_allocated_since_gc_start() { 2008 OrderAccess::release_store_fence(&_bytes_allocated_since_gc_start, (size_t)0); 2009 } 2010 2011 void ShenandoahHeap::set_degenerated_gc_in_progress(bool in_progress) { 2012 _degenerated_gc_in_progress.set_cond(in_progress); 2013 } 2014 2015 void ShenandoahHeap::set_full_gc_in_progress(bool in_progress) { 2016 _full_gc_in_progress.set_cond(in_progress); 2017 } 2018 2019 void ShenandoahHeap::set_full_gc_move_in_progress(bool in_progress) { 2020 assert (is_full_gc_in_progress(), "should be"); 2021 _full_gc_move_in_progress.set_cond(in_progress); 2022 } 2023 2024 void ShenandoahHeap::set_update_refs_in_progress(bool in_progress) { 2025 set_gc_state_mask(UPDATEREFS, in_progress); 2026 } 2027 2028 void ShenandoahHeap::register_nmethod(nmethod* nm) { 2029 ShenandoahCodeRoots::add_nmethod(nm); 2030 } 2031 2032 void ShenandoahHeap::unregister_nmethod(nmethod* nm) { 2033 ShenandoahCodeRoots::remove_nmethod(nm); 2034 } 2035 2036 oop ShenandoahHeap::pin_object(JavaThread* thr, oop o) { 2037 heap_region_containing(o)->record_pin(); 2038 return o; 2039 } 2040 2041 void ShenandoahHeap::unpin_object(JavaThread* thr, oop o) { 2042 heap_region_containing(o)->record_unpin(); 2043 } 2044 2045 void ShenandoahHeap::sync_pinned_region_status() { 2046 ShenandoahHeapLocker locker(lock()); 2047 2048 for (size_t i = 0; i < num_regions(); i++) { 2049 ShenandoahHeapRegion *r = get_region(i); 2050 if (r->is_active()) { 2051 if (r->is_pinned()) { 2052 if (r->pin_count() == 0) { 2053 r->make_unpinned(); 2054 } 2055 } else { 2056 if (r->pin_count() > 0) { 2057 r->make_pinned(); 2058 } 2059 } 2060 } 2061 } 2062 2063 assert_pinned_region_status(); 2064 } 2065 2066 #ifdef ASSERT 2067 void ShenandoahHeap::assert_pinned_region_status() { 2068 for (size_t i = 0; i < num_regions(); i++) { 2069 ShenandoahHeapRegion* r = get_region(i); 2070 assert((r->is_pinned() && r->pin_count() > 0) || (!r->is_pinned() && r->pin_count() == 0), 2071 err_msg("Region " SIZE_FORMAT " pinning status is inconsistent", i)); 2072 } 2073 } 2074 #endif 2075 2076 GCTimer* ShenandoahHeap::gc_timer() const { 2077 return _gc_timer; 2078 } 2079 2080 #ifdef ASSERT 2081 void ShenandoahHeap::assert_gc_workers(uint nworkers) { 2082 assert(nworkers > 0 && nworkers <= max_workers(), "Sanity"); 2083 2084 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) { 2085 if (UseDynamicNumberOfGCThreads || 2086 (FLAG_IS_DEFAULT(ParallelGCThreads) && ForceDynamicNumberOfGCThreads)) { 2087 assert(nworkers <= ParallelGCThreads, "Cannot use more than it has"); 2088 } else { 2089 // Use ParallelGCThreads inside safepoints 2090 assert(nworkers == ParallelGCThreads, "Use ParalleGCThreads within safepoints"); 2091 } 2092 } else { 2093 if (UseDynamicNumberOfGCThreads || 2094 (FLAG_IS_DEFAULT(ConcGCThreads) && ForceDynamicNumberOfGCThreads)) { 2095 assert(nworkers <= ConcGCThreads, "Cannot use more than it has"); 2096 } else { 2097 // Use ConcGCThreads outside safepoints 2098 assert(nworkers == ConcGCThreads, "Use ConcGCThreads outside safepoints"); 2099 } 2100 } 2101 } 2102 #endif 2103 2104 ShenandoahVerifier* ShenandoahHeap::verifier() { 2105 guarantee(ShenandoahVerify, "Should be enabled"); 2106 assert (_verifier != NULL, "sanity"); 2107 return _verifier; 2108 } 2109 2110 ShenandoahUpdateHeapRefsClosure::ShenandoahUpdateHeapRefsClosure() : 2111 _heap(ShenandoahHeap::heap()) {} 2112 2113 class ShenandoahUpdateHeapRefsTask : public AbstractGangTask { 2114 private: 2115 ShenandoahHeap* _heap; 2116 ShenandoahRegionIterator* _regions; 2117 bool _concurrent; 2118 2119 public: 2120 ShenandoahUpdateHeapRefsTask(ShenandoahRegionIterator* regions, bool concurrent) : 2121 AbstractGangTask("Concurrent Update References Task"), 2122 _heap(ShenandoahHeap::heap()), 2123 _regions(regions), 2124 _concurrent(concurrent) { 2125 } 2126 2127 void work(uint worker_id) { 2128 ShenandoahConcurrentWorkerSession worker_session(worker_id); 2129 ShenandoahUpdateHeapRefsClosure cl; 2130 ShenandoahHeapRegion* r = _regions->next(); 2131 ShenandoahMarkingContext* const ctx = _heap->complete_marking_context(); 2132 while (r != NULL) { 2133 HeapWord* update_watermark = r->get_update_watermark(); 2134 assert (update_watermark >= r->bottom(), "sanity"); 2135 if (r->is_active() && !r->is_cset()) { 2136 _heap->marked_object_oop_iterate(r, &cl, update_watermark); 2137 } 2138 if (ShenandoahPacing) { 2139 _heap->pacer()->report_updaterefs(pointer_delta(update_watermark, r->bottom())); 2140 } 2141 if (_heap->cancelled_gc()) { 2142 return; 2143 } 2144 r = _regions->next(); 2145 } 2146 } 2147 }; 2148 2149 void ShenandoahHeap::update_heap_references(bool concurrent) { 2150 ShenandoahUpdateHeapRefsTask task(&_update_refs_iterator, concurrent); 2151 workers()->run_task(&task); 2152 } 2153 2154 void ShenandoahHeap::op_init_updaterefs() { 2155 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint"); 2156 2157 set_evacuation_in_progress(false); 2158 2159 if (ShenandoahVerify) { 2160 if (!is_degenerated_gc_in_progress()) { 2161 verifier()->verify_roots_no_forwarded_except(ShenandoahRootVerifier::ThreadRoots); 2162 } 2163 verifier()->verify_before_updaterefs(); 2164 } 2165 2166 set_update_refs_in_progress(true); 2167 2168 { 2169 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_refs_prepare); 2170 2171 make_parsable(true); 2172 2173 // Reset iterator. 2174 _update_refs_iterator.reset(); 2175 } 2176 2177 if (ShenandoahPacing) { 2178 pacer()->setup_for_updaterefs(); 2179 } 2180 } 2181 2182 class ShenandoahFinalUpdateRefsUpdateRegionStateClosure : public ShenandoahHeapRegionClosure { 2183 private: 2184 ShenandoahHeapLock* const _lock; 2185 2186 public: 2187 ShenandoahFinalUpdateRefsUpdateRegionStateClosure() : _lock(ShenandoahHeap::heap()->lock()) {} 2188 2189 void heap_region_do(ShenandoahHeapRegion* r) { 2190 // Drop unnecessary "pinned" state from regions that does not have CP marks 2191 // anymore, as this would allow trashing them. 2192 2193 if (r->is_active()) { 2194 if (r->is_pinned()) { 2195 if (r->pin_count() == 0) { 2196 ShenandoahHeapLocker locker(_lock); 2197 r->make_unpinned(); 2198 } 2199 } else { 2200 if (r->pin_count() > 0) { 2201 ShenandoahHeapLocker locker(_lock); 2202 r->make_pinned(); 2203 } 2204 } 2205 } 2206 } 2207 2208 bool is_thread_safe() { return true; } 2209 }; 2210 2211 void ShenandoahHeap::op_final_updaterefs() { 2212 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint"); 2213 2214 // Check if there is left-over work, and finish it 2215 if (_update_refs_iterator.has_next()) { 2216 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_finish_work); 2217 2218 // Finish updating references where we left off. 2219 clear_cancelled_gc(); 2220 update_heap_references(false); 2221 } 2222 2223 // Clear cancelled GC, if set. On cancellation path, the block before would handle 2224 // everything. On degenerated paths, cancelled gc would not be set anyway. 2225 if (cancelled_gc()) { 2226 clear_cancelled_gc(); 2227 } 2228 assert(!cancelled_gc(), "Should have been done right before"); 2229 2230 if (ShenandoahVerify && !is_degenerated_gc_in_progress()) { 2231 verifier()->verify_roots_no_forwarded_except(ShenandoahRootVerifier::ThreadRoots); 2232 } 2233 2234 if (is_degenerated_gc_in_progress()) { 2235 concurrent_mark()->update_roots(ShenandoahPhaseTimings::degen_gc_update_roots); 2236 } else { 2237 concurrent_mark()->update_thread_roots(ShenandoahPhaseTimings::final_update_refs_roots); 2238 } 2239 2240 // Has to be done before cset is clear 2241 if (ShenandoahVerify) { 2242 verifier()->verify_roots_in_to_space(); 2243 } 2244 2245 { 2246 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_trash_cset); 2247 trash_cset_regions(); 2248 } 2249 2250 set_has_forwarded_objects(false); 2251 set_update_refs_in_progress(false); 2252 2253 if (ShenandoahVerify) { 2254 verifier()->verify_after_updaterefs(); 2255 } 2256 2257 if (VerifyAfterGC) { 2258 Universe::verify(); 2259 } 2260 2261 { 2262 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_update_region_states); 2263 ShenandoahFinalUpdateRefsUpdateRegionStateClosure cl; 2264 parallel_heap_region_iterate(&cl); 2265 2266 assert_pinned_region_status(); 2267 } 2268 2269 { 2270 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_rebuild_freeset); 2271 ShenandoahHeapLocker locker(lock()); 2272 _free_set->rebuild(); 2273 } 2274 } 2275 2276 void ShenandoahHeap::print_extended_on(outputStream *st) const { 2277 print_on(st); 2278 print_heap_regions_on(st); 2279 } 2280 2281 bool ShenandoahHeap::is_bitmap_slice_committed(ShenandoahHeapRegion* r, bool skip_self) { 2282 size_t slice = r->index() / _bitmap_regions_per_slice; 2283 2284 size_t regions_from = _bitmap_regions_per_slice * slice; 2285 size_t regions_to = MIN2(num_regions(), _bitmap_regions_per_slice * (slice + 1)); 2286 for (size_t g = regions_from; g < regions_to; g++) { 2287 assert (g / _bitmap_regions_per_slice == slice, "same slice"); 2288 if (skip_self && g == r->index()) continue; 2289 if (get_region(g)->is_committed()) { 2290 return true; 2291 } 2292 } 2293 return false; 2294 } 2295 2296 bool ShenandoahHeap::commit_bitmap_slice(ShenandoahHeapRegion* r) { 2297 shenandoah_assert_heaplocked(); 2298 2299 // Bitmaps in special regions do not need commits 2300 if (_bitmap_region_special) { 2301 return true; 2302 } 2303 2304 if (is_bitmap_slice_committed(r, true)) { 2305 // Some other region from the group is already committed, meaning the bitmap 2306 // slice is already committed, we exit right away. 2307 return true; 2308 } 2309 2310 // Commit the bitmap slice: 2311 size_t slice = r->index() / _bitmap_regions_per_slice; 2312 size_t off = _bitmap_bytes_per_slice * slice; 2313 size_t len = _bitmap_bytes_per_slice; 2314 char* start = (char*) _bitmap_region.start() + off; 2315 2316 if (!os::commit_memory(start, len, false)) { 2317 return false; 2318 } 2319 2320 if (AlwaysPreTouch) { 2321 os::pretouch_memory(start, start + len); 2322 } 2323 2324 return true; 2325 } 2326 2327 bool ShenandoahHeap::uncommit_bitmap_slice(ShenandoahHeapRegion *r) { 2328 shenandoah_assert_heaplocked(); 2329 2330 // Bitmaps in special regions do not need uncommits 2331 if (_bitmap_region_special) { 2332 return true; 2333 } 2334 2335 if (is_bitmap_slice_committed(r, true)) { 2336 // Some other region from the group is still committed, meaning the bitmap 2337 // slice is should stay committed, exit right away. 2338 return true; 2339 } 2340 2341 // Uncommit the bitmap slice: 2342 size_t slice = r->index() / _bitmap_regions_per_slice; 2343 size_t off = _bitmap_bytes_per_slice * slice; 2344 size_t len = _bitmap_bytes_per_slice; 2345 if (!os::uncommit_memory((char*)_bitmap_region.start() + off, len)) { 2346 return false; 2347 } 2348 return true; 2349 } 2350 2351 void ShenandoahHeap::vmop_entry_init_mark() { 2352 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters()); 2353 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_mark_gross); 2354 2355 try_inject_alloc_failure(); 2356 VM_ShenandoahInitMark op; 2357 VMThread::execute(&op); // jump to entry_init_mark() under safepoint 2358 } 2359 2360 void ShenandoahHeap::vmop_entry_final_mark() { 2361 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters()); 2362 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_mark_gross); 2363 2364 try_inject_alloc_failure(); 2365 VM_ShenandoahFinalMarkStartEvac op; 2366 VMThread::execute(&op); // jump to entry_final_mark under safepoint 2367 } 2368 2369 void ShenandoahHeap::vmop_entry_init_updaterefs() { 2370 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters()); 2371 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_refs_gross); 2372 2373 try_inject_alloc_failure(); 2374 VM_ShenandoahInitUpdateRefs op; 2375 VMThread::execute(&op); 2376 } 2377 2378 void ShenandoahHeap::vmop_entry_final_updaterefs() { 2379 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters()); 2380 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_gross); 2381 2382 try_inject_alloc_failure(); 2383 VM_ShenandoahFinalUpdateRefs op; 2384 VMThread::execute(&op); 2385 } 2386 2387 void ShenandoahHeap::vmop_entry_full(GCCause::Cause cause) { 2388 TraceCollectorStats tcs(monitoring_support()->full_stw_collection_counters()); 2389 ShenandoahGCPhase phase(ShenandoahPhaseTimings::full_gc_gross); 2390 2391 try_inject_alloc_failure(); 2392 VM_ShenandoahFullGC op(cause); 2393 VMThread::execute(&op); 2394 } 2395 2396 void ShenandoahHeap::vmop_degenerated(ShenandoahDegenPoint point) { 2397 TraceCollectorStats tcs(monitoring_support()->full_stw_collection_counters()); 2398 ShenandoahGCPhase phase(ShenandoahPhaseTimings::degen_gc_gross); 2399 2400 VM_ShenandoahDegeneratedGC degenerated_gc((int)point); 2401 VMThread::execute(°enerated_gc); 2402 } 2403 2404 void ShenandoahHeap::entry_init_mark() { 2405 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_mark); 2406 2407 const char* msg = init_mark_event_message(); 2408 GCTraceTime time(msg, PrintGC, _gc_timer, tracer()->gc_id()); 2409 EventMark em("%s", msg); 2410 2411 ShenandoahWorkerScope scope(workers(), 2412 ShenandoahWorkerPolicy::calc_workers_for_init_marking(), 2413 "init marking"); 2414 2415 op_init_mark(); 2416 } 2417 2418 void ShenandoahHeap::entry_final_mark() { 2419 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_mark); 2420 2421 const char* msg = final_mark_event_message(); 2422 GCTraceTime time(msg, PrintGC, _gc_timer, tracer()->gc_id()); 2423 EventMark em("%s", msg); 2424 2425 ShenandoahWorkerScope scope(workers(), 2426 ShenandoahWorkerPolicy::calc_workers_for_final_marking(), 2427 "final marking"); 2428 2429 op_final_mark(); 2430 } 2431 2432 void ShenandoahHeap::entry_init_updaterefs() { 2433 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_refs); 2434 2435 static const char* msg = "Pause Init Update Refs"; 2436 GCTraceTime time(msg, PrintGC, _gc_timer, tracer()->gc_id()); 2437 EventMark em("%s", msg); 2438 2439 // No workers used in this phase, no setup required 2440 2441 op_init_updaterefs(); 2442 } 2443 2444 void ShenandoahHeap::entry_final_updaterefs() { 2445 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs); 2446 2447 static const char* msg = "Pause Final Update Refs"; 2448 GCTraceTime time(msg, PrintGC, _gc_timer, tracer()->gc_id()); 2449 EventMark em("%s", msg); 2450 2451 ShenandoahWorkerScope scope(workers(), 2452 ShenandoahWorkerPolicy::calc_workers_for_final_update_ref(), 2453 "final reference update"); 2454 2455 op_final_updaterefs(); 2456 } 2457 2458 void ShenandoahHeap::entry_full(GCCause::Cause cause) { 2459 ShenandoahGCPhase phase(ShenandoahPhaseTimings::full_gc); 2460 2461 static const char* msg = "Pause Full"; 2462 GCTraceTime time(msg, PrintGC, _gc_timer, tracer()->gc_id(), true); 2463 EventMark em("%s", msg); 2464 2465 ShenandoahWorkerScope scope(workers(), 2466 ShenandoahWorkerPolicy::calc_workers_for_fullgc(), 2467 "full gc"); 2468 2469 op_full(cause); 2470 } 2471 2472 void ShenandoahHeap::entry_degenerated(int point) { 2473 ShenandoahGCPhase phase(ShenandoahPhaseTimings::degen_gc); 2474 2475 ShenandoahDegenPoint dpoint = (ShenandoahDegenPoint)point; 2476 const char* msg = degen_event_message(dpoint); 2477 GCTraceTime time(msg, PrintGC, _gc_timer, tracer()->gc_id(), true); 2478 EventMark em("%s", msg); 2479 2480 ShenandoahWorkerScope scope(workers(), 2481 ShenandoahWorkerPolicy::calc_workers_for_stw_degenerated(), 2482 "stw degenerated gc"); 2483 2484 set_degenerated_gc_in_progress(true); 2485 op_degenerated(dpoint); 2486 set_degenerated_gc_in_progress(false); 2487 } 2488 2489 void ShenandoahHeap::entry_mark() { 2490 TraceCollectorStats tcs(monitoring_support()->concurrent_collection_counters()); 2491 2492 const char* msg = conc_mark_event_message(); 2493 GCTraceTime time(msg, PrintGC, NULL, tracer()->gc_id()); 2494 EventMark em("%s", msg); 2495 2496 ShenandoahWorkerScope scope(workers(), 2497 ShenandoahWorkerPolicy::calc_workers_for_conc_marking(), 2498 "concurrent marking"); 2499 2500 try_inject_alloc_failure(); 2501 op_mark(); 2502 } 2503 2504 void ShenandoahHeap::entry_evac() { 2505 ShenandoahGCPhase conc_evac_phase(ShenandoahPhaseTimings::conc_evac); 2506 TraceCollectorStats tcs(monitoring_support()->concurrent_collection_counters()); 2507 2508 static const char *msg = "Concurrent evacuation"; 2509 GCTraceTime time(msg, PrintGC, NULL, tracer()->gc_id()); 2510 EventMark em("%s", msg); 2511 2512 ShenandoahWorkerScope scope(workers(), 2513 ShenandoahWorkerPolicy::calc_workers_for_conc_evac(), 2514 "concurrent evacuation"); 2515 2516 try_inject_alloc_failure(); 2517 op_conc_evac(); 2518 } 2519 2520 void ShenandoahHeap::entry_updaterefs() { 2521 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_update_refs); 2522 2523 static const char* msg = "Concurrent update references"; 2524 GCTraceTime time(msg, PrintGC, NULL, tracer()->gc_id()); 2525 EventMark em("%s", msg); 2526 2527 ShenandoahWorkerScope scope(workers(), 2528 ShenandoahWorkerPolicy::calc_workers_for_conc_update_ref(), 2529 "concurrent reference update"); 2530 2531 try_inject_alloc_failure(); 2532 op_updaterefs(); 2533 } 2534 2535 void ShenandoahHeap::entry_cleanup_early() { 2536 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_cleanup_early); 2537 2538 static const char* msg = "Concurrent cleanup"; 2539 GCTraceTime time(msg, PrintGC, NULL, tracer()->gc_id(), true); 2540 EventMark em("%s", msg); 2541 2542 // This phase does not use workers, no need for setup 2543 2544 try_inject_alloc_failure(); 2545 op_cleanup_early(); 2546 } 2547 2548 void ShenandoahHeap::entry_cleanup_complete() { 2549 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_cleanup_complete); 2550 2551 static const char* msg = "Concurrent cleanup"; 2552 GCTraceTime time(msg, PrintGC, NULL, tracer()->gc_id(), true); 2553 EventMark em("%s", msg); 2554 2555 // This phase does not use workers, no need for setup 2556 2557 try_inject_alloc_failure(); 2558 op_cleanup_complete(); 2559 } 2560 2561 void ShenandoahHeap::entry_reset() { 2562 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_reset); 2563 2564 static const char* msg = "Concurrent reset"; 2565 GCTraceTime time(msg, PrintGC, NULL, tracer()->gc_id()); 2566 EventMark em("%s", msg); 2567 2568 ShenandoahWorkerScope scope(workers(), 2569 ShenandoahWorkerPolicy::calc_workers_for_conc_reset(), 2570 "concurrent reset"); 2571 2572 try_inject_alloc_failure(); 2573 op_reset(); 2574 } 2575 2576 void ShenandoahHeap::entry_preclean() { 2577 if (ShenandoahPreclean && process_references()) { 2578 ShenandoahGCPhase conc_preclean(ShenandoahPhaseTimings::conc_preclean); 2579 2580 static const char* msg = "Concurrent precleaning"; 2581 GCTraceTime time(msg, PrintGC, NULL, tracer()->gc_id()); 2582 EventMark em("%s", msg); 2583 2584 ShenandoahWorkerScope scope(workers(), 2585 ShenandoahWorkerPolicy::calc_workers_for_conc_preclean(), 2586 "concurrent preclean", 2587 /* check_workers = */ false); 2588 2589 try_inject_alloc_failure(); 2590 op_preclean(); 2591 } 2592 } 2593 2594 void ShenandoahHeap::entry_uncommit(double shrink_before, size_t shrink_until) { 2595 static const char *msg = "Concurrent uncommit"; 2596 GCTraceTime time(msg, PrintGC, NULL, tracer()->gc_id(), true); 2597 EventMark em("%s", msg); 2598 2599 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_uncommit); 2600 2601 op_uncommit(shrink_before, shrink_until); 2602 } 2603 2604 void ShenandoahHeap::try_inject_alloc_failure() { 2605 if (ShenandoahAllocFailureALot && !cancelled_gc() && ((os::random() % 1000) > 950)) { 2606 _inject_alloc_failure.set(); 2607 os::naked_short_sleep(1); 2608 if (cancelled_gc()) { 2609 log_info(gc)("Allocation failure was successfully injected"); 2610 } 2611 } 2612 } 2613 2614 bool ShenandoahHeap::should_inject_alloc_failure() { 2615 return _inject_alloc_failure.is_set() && _inject_alloc_failure.try_unset(); 2616 } 2617 2618 void ShenandoahHeap::enter_evacuation() { 2619 _oom_evac_handler.enter_evacuation(); 2620 } 2621 2622 void ShenandoahHeap::leave_evacuation() { 2623 _oom_evac_handler.leave_evacuation(); 2624 } 2625 2626 ShenandoahRegionIterator::ShenandoahRegionIterator() : 2627 _heap(ShenandoahHeap::heap()), 2628 _index(0) {} 2629 2630 ShenandoahRegionIterator::ShenandoahRegionIterator(ShenandoahHeap* heap) : 2631 _heap(heap), 2632 _index(0) {} 2633 2634 void ShenandoahRegionIterator::reset() { 2635 _index = 0; 2636 } 2637 2638 bool ShenandoahRegionIterator::has_next() const { 2639 return _index < (jint)_heap->num_regions(); 2640 } 2641 2642 char ShenandoahHeap::gc_state() { 2643 return _gc_state.raw_value(); 2644 } 2645 2646 const char* ShenandoahHeap::init_mark_event_message() const { 2647 assert(!has_forwarded_objects(), "Should not have forwarded objects here"); 2648 2649 bool proc_refs = process_references(); 2650 bool unload_cls = unload_classes(); 2651 2652 if (proc_refs && unload_cls) { 2653 return "Pause Init Mark (process weakrefs) (unload classes)"; 2654 } else if (proc_refs) { 2655 return "Pause Init Mark (process weakrefs)"; 2656 } else if (unload_cls) { 2657 return "Pause Init Mark (unload classes)"; 2658 } else { 2659 return "Pause Init Mark"; 2660 } 2661 } 2662 2663 const char* ShenandoahHeap::final_mark_event_message() const { 2664 assert(!has_forwarded_objects(), "Should not have forwarded objects here"); 2665 2666 bool proc_refs = process_references(); 2667 bool unload_cls = unload_classes(); 2668 2669 if (proc_refs && unload_cls) { 2670 return "Pause Final Mark (process weakrefs) (unload classes)"; 2671 } else if (proc_refs) { 2672 return "Pause Final Mark (process weakrefs)"; 2673 } else if (unload_cls) { 2674 return "Pause Final Mark (unload classes)"; 2675 } else { 2676 return "Pause Final Mark"; 2677 } 2678 } 2679 2680 const char* ShenandoahHeap::conc_mark_event_message() const { 2681 assert(!has_forwarded_objects(), "Should not have forwarded objects here"); 2682 2683 bool proc_refs = process_references(); 2684 bool unload_cls = unload_classes(); 2685 2686 if (proc_refs && unload_cls) { 2687 return "Concurrent marking (process weakrefs) (unload classes)"; 2688 } else if (proc_refs) { 2689 return "Concurrent marking (process weakrefs)"; 2690 } else if (unload_cls) { 2691 return "Concurrent marking (unload classes)"; 2692 } else { 2693 return "Concurrent marking"; 2694 } 2695 } 2696 2697 const char* ShenandoahHeap::degen_event_message(ShenandoahDegenPoint point) const { 2698 switch (point) { 2699 case _degenerated_unset: 2700 return "Pause Degenerated GC (<UNSET>)"; 2701 case _degenerated_outside_cycle: 2702 return "Pause Degenerated GC (Outside of Cycle)"; 2703 case _degenerated_mark: 2704 return "Pause Degenerated GC (Mark)"; 2705 case _degenerated_evac: 2706 return "Pause Degenerated GC (Evacuation)"; 2707 case _degenerated_updaterefs: 2708 return "Pause Degenerated GC (Update Refs)"; 2709 default: 2710 ShouldNotReachHere(); 2711 return "ERROR"; 2712 } 2713 } 2714 2715 ShenandoahLiveData* ShenandoahHeap::get_liveness_cache(uint worker_id) { 2716 #ifdef ASSERT 2717 assert(_liveness_cache != NULL, "sanity"); 2718 assert(worker_id < _max_workers, "sanity"); 2719 for (uint i = 0; i < num_regions(); i++) { 2720 assert(_liveness_cache[worker_id][i] == 0, "liveness cache should be empty"); 2721 } 2722 #endif 2723 return _liveness_cache[worker_id]; 2724 } 2725 2726 void ShenandoahHeap::flush_liveness_cache(uint worker_id) { 2727 assert(worker_id < _max_workers, "sanity"); 2728 assert(_liveness_cache != NULL, "sanity"); 2729 ShenandoahLiveData* ld = _liveness_cache[worker_id]; 2730 for (uint i = 0; i < num_regions(); i++) { 2731 ShenandoahLiveData live = ld[i]; 2732 if (live > 0) { 2733 ShenandoahHeapRegion* r = get_region(i); 2734 r->increase_live_data_gc_words(live); 2735 ld[i] = 0; 2736 } 2737 } 2738 }