1 /* 2 * Copyright (c) 2001, 2023, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "classfile/classLoaderDataGraph.hpp" 27 #include "classfile/metadataOnStackMark.hpp" 28 #include "classfile/stringTable.hpp" 29 #include "code/codeCache.hpp" 30 #include "code/icBuffer.hpp" 31 #include "compiler/oopMap.hpp" 32 #include "gc/g1/g1Allocator.inline.hpp" 33 #include "gc/g1/g1Arguments.hpp" 34 #include "gc/g1/g1BarrierSet.hpp" 35 #include "gc/g1/g1BatchedTask.hpp" 36 #include "gc/g1/g1CollectedHeap.inline.hpp" 37 #include "gc/g1/g1CollectionSet.hpp" 38 #include "gc/g1/g1CollectionSetCandidates.hpp" 39 #include "gc/g1/g1CollectorState.hpp" 40 #include "gc/g1/g1ConcurrentRefine.hpp" 41 #include "gc/g1/g1ConcurrentRefineThread.hpp" 42 #include "gc/g1/g1ConcurrentMarkThread.inline.hpp" 43 #include "gc/g1/g1DirtyCardQueue.hpp" 44 #include "gc/g1/g1EvacStats.inline.hpp" 45 #include "gc/g1/g1FullCollector.hpp" 46 #include "gc/g1/g1GCCounters.hpp" 47 #include "gc/g1/g1GCParPhaseTimesTracker.hpp" 48 #include "gc/g1/g1GCPhaseTimes.hpp" 49 #include "gc/g1/g1GCPauseType.hpp" 50 #include "gc/g1/g1HeapSizingPolicy.hpp" 51 #include "gc/g1/g1HeapTransition.hpp" 52 #include "gc/g1/g1HeapVerifier.hpp" 53 #include "gc/g1/g1InitLogger.hpp" 54 #include "gc/g1/g1MemoryPool.hpp" 55 #include "gc/g1/g1MonotonicArenaFreeMemoryTask.hpp" 56 #include "gc/g1/g1OopClosures.inline.hpp" 57 #include "gc/g1/g1ParallelCleaning.hpp" 58 #include "gc/g1/g1ParScanThreadState.inline.hpp" 59 #include "gc/g1/g1PeriodicGCTask.hpp" 60 #include "gc/g1/g1Policy.hpp" 61 #include "gc/g1/g1RedirtyCardsQueue.hpp" 62 #include "gc/g1/g1RegionToSpaceMapper.hpp" 63 #include "gc/g1/g1RemSet.hpp" 64 #include "gc/g1/g1RootClosures.hpp" 65 #include "gc/g1/g1RootProcessor.hpp" 66 #include "gc/g1/g1SATBMarkQueueSet.hpp" 67 #include "gc/g1/g1ServiceThread.hpp" 68 #include "gc/g1/g1ThreadLocalData.hpp" 69 #include "gc/g1/g1Trace.hpp" 70 #include "gc/g1/g1UncommitRegionTask.hpp" 71 #include "gc/g1/g1VMOperations.hpp" 72 #include "gc/g1/g1YoungCollector.hpp" 73 #include "gc/g1/g1YoungGCEvacFailureInjector.hpp" 74 #include "gc/g1/heapRegion.inline.hpp" 75 #include "gc/g1/heapRegionRemSet.inline.hpp" 76 #include "gc/g1/heapRegionSet.inline.hpp" 77 #include "gc/shared/concurrentGCBreakpoints.hpp" 78 #include "gc/shared/gcBehaviours.hpp" 79 #include "gc/shared/gcHeapSummary.hpp" 80 #include "gc/shared/gcId.hpp" 81 #include "gc/shared/gcLocker.inline.hpp" 82 #include "gc/shared/gcTimer.hpp" 83 #include "gc/shared/gcTraceTime.inline.hpp" 84 #include "gc/shared/generationSpec.hpp" 85 #include "gc/shared/isGCActiveMark.hpp" 86 #include "gc/shared/locationPrinter.inline.hpp" 87 #include "gc/shared/oopStorageParState.hpp" 88 #include "gc/shared/preservedMarks.inline.hpp" 89 #include "gc/shared/referenceProcessor.inline.hpp" 90 #include "gc/shared/suspendibleThreadSet.hpp" 91 #include "gc/shared/taskqueue.inline.hpp" 92 #include "gc/shared/taskTerminator.hpp" 93 #include "gc/shared/tlab_globals.hpp" 94 #include "gc/shared/workerPolicy.hpp" 95 #include "gc/shared/weakProcessor.inline.hpp" 96 #include "logging/log.hpp" 97 #include "memory/allocation.hpp" 98 #include "memory/heapInspection.hpp" 99 #include "memory/iterator.hpp" 100 #include "memory/metaspaceUtils.hpp" 101 #include "memory/resourceArea.hpp" 102 #include "memory/universe.hpp" 103 #include "oops/access.inline.hpp" 104 #include "oops/compressedOops.inline.hpp" 105 #include "oops/oop.inline.hpp" 106 #include "runtime/atomic.hpp" 107 #include "runtime/handles.inline.hpp" 108 #include "runtime/init.hpp" 109 #include "runtime/java.hpp" 110 #include "runtime/orderAccess.hpp" 111 #include "runtime/threadSMR.hpp" 112 #include "runtime/vmThread.hpp" 113 #include "utilities/align.hpp" 114 #include "utilities/autoRestore.hpp" 115 #include "utilities/bitMap.inline.hpp" 116 #include "utilities/globalDefinitions.hpp" 117 #include "utilities/stack.inline.hpp" 118 119 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0; 120 121 // INVARIANTS/NOTES 122 // 123 // All allocation activity covered by the G1CollectedHeap interface is 124 // serialized by acquiring the HeapLock. This happens in mem_allocate 125 // and allocate_new_tlab, which are the "entry" points to the 126 // allocation code from the rest of the JVM. (Note that this does not 127 // apply to TLAB allocation, which is not part of this interface: it 128 // is done by clients of this interface.) 129 130 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) { 131 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions); 132 } 133 134 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) { 135 // The from card cache is not the memory that is actually committed. So we cannot 136 // take advantage of the zero_filled parameter. 137 reset_from_card_cache(start_idx, num_regions); 138 } 139 140 void G1CollectedHeap::run_batch_task(G1BatchedTask* cl) { 141 uint num_workers = MAX2(1u, MIN2(cl->num_workers_estimate(), workers()->active_workers())); 142 cl->set_max_workers(num_workers); 143 workers()->run_task(cl, num_workers); 144 } 145 146 uint G1CollectedHeap::get_chunks_per_region() { 147 uint log_region_size = HeapRegion::LogOfHRGrainBytes; 148 // Limit the expected input values to current known possible values of the 149 // (log) region size. Adjust as necessary after testing if changing the permissible 150 // values for region size. 151 assert(log_region_size >= 20 && log_region_size <= 29, 152 "expected value in [20,29], but got %u", log_region_size); 153 return 1u << (log_region_size / 2 - 4); 154 } 155 156 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index, 157 MemRegion mr) { 158 return new HeapRegion(hrs_index, bot(), mr, &_card_set_config); 159 } 160 161 // Private methods. 162 163 HeapRegion* G1CollectedHeap::new_region(size_t word_size, 164 HeapRegionType type, 165 bool do_expand, 166 uint node_index) { 167 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords, 168 "the only time we use this to allocate a humongous region is " 169 "when we are allocating a single humongous region"); 170 171 HeapRegion* res = _hrm.allocate_free_region(type, node_index); 172 173 if (res == NULL && do_expand) { 174 // Currently, only attempts to allocate GC alloc regions set 175 // do_expand to true. So, we should only reach here during a 176 // safepoint. 177 assert(SafepointSynchronize::is_at_safepoint(), "invariant"); 178 179 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B", 180 word_size * HeapWordSize); 181 182 assert(word_size * HeapWordSize < HeapRegion::GrainBytes, 183 "This kind of expansion should never be more than one region. Size: " SIZE_FORMAT, 184 word_size * HeapWordSize); 185 if (expand_single_region(node_index)) { 186 // Given that expand_single_region() succeeded in expanding the heap, and we 187 // always expand the heap by an amount aligned to the heap 188 // region size, the free list should in theory not be empty. 189 // In either case allocate_free_region() will check for NULL. 190 res = _hrm.allocate_free_region(type, node_index); 191 } 192 } 193 return res; 194 } 195 196 HeapWord* 197 G1CollectedHeap::humongous_obj_allocate_initialize_regions(HeapRegion* first_hr, 198 uint num_regions, 199 size_t word_size) { 200 assert(first_hr != NULL, "pre-condition"); 201 assert(is_humongous(word_size), "word_size should be humongous"); 202 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition"); 203 204 // Index of last region in the series. 205 uint first = first_hr->hrm_index(); 206 uint last = first + num_regions - 1; 207 208 // We need to initialize the region(s) we just discovered. This is 209 // a bit tricky given that it can happen concurrently with 210 // refinement threads refining cards on these regions and 211 // potentially wanting to refine the BOT as they are scanning 212 // those cards (this can happen shortly after a cleanup; see CR 213 // 6991377). So we have to set up the region(s) carefully and in 214 // a specific order. 215 216 // The word size sum of all the regions we will allocate. 217 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords; 218 assert(word_size <= word_size_sum, "sanity"); 219 220 // The passed in hr will be the "starts humongous" region. The header 221 // of the new object will be placed at the bottom of this region. 222 HeapWord* new_obj = first_hr->bottom(); 223 // This will be the new top of the new object. 224 HeapWord* obj_top = new_obj + word_size; 225 226 // First, we need to zero the header of the space that we will be 227 // allocating. When we update top further down, some refinement 228 // threads might try to scan the region. By zeroing the header we 229 // ensure that any thread that will try to scan the region will 230 // come across the zero klass word and bail out. 231 // 232 // NOTE: It would not have been correct to have used 233 // CollectedHeap::fill_with_object() and make the space look like 234 // an int array. The thread that is doing the allocation will 235 // later update the object header to a potentially different array 236 // type and, for a very short period of time, the klass and length 237 // fields will be inconsistent. This could cause a refinement 238 // thread to calculate the object size incorrectly. 239 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0); 240 241 // Next, pad out the unused tail of the last region with filler 242 // objects, for improved usage accounting. 243 // How many words we use for filler objects. 244 size_t word_fill_size = word_size_sum - word_size; 245 246 // How many words memory we "waste" which cannot hold a filler object. 247 size_t words_not_fillable = 0; 248 249 if (word_fill_size >= min_fill_size()) { 250 fill_with_objects(obj_top, word_fill_size); 251 } else if (word_fill_size > 0) { 252 // We have space to fill, but we cannot fit an object there. 253 words_not_fillable = word_fill_size; 254 word_fill_size = 0; 255 } 256 257 // We will set up the first region as "starts humongous". This 258 // will also update the BOT covering all the regions to reflect 259 // that there is a single object that starts at the bottom of the 260 // first region. 261 first_hr->set_starts_humongous(obj_top, word_fill_size); 262 _policy->remset_tracker()->update_at_allocate(first_hr); 263 // Then, if there are any, we will set up the "continues 264 // humongous" regions. 265 HeapRegion* hr = NULL; 266 for (uint i = first + 1; i <= last; ++i) { 267 hr = region_at(i); 268 hr->set_continues_humongous(first_hr); 269 _policy->remset_tracker()->update_at_allocate(hr); 270 } 271 272 // Up to this point no concurrent thread would have been able to 273 // do any scanning on any region in this series. All the top 274 // fields still point to bottom, so the intersection between 275 // [bottom,top] and [card_start,card_end] will be empty. Before we 276 // update the top fields, we'll do a storestore to make sure that 277 // no thread sees the update to top before the zeroing of the 278 // object header and the BOT initialization. 279 OrderAccess::storestore(); 280 281 // Now, we will update the top fields of the "continues humongous" 282 // regions except the last one. 283 for (uint i = first; i < last; ++i) { 284 hr = region_at(i); 285 hr->set_top(hr->end()); 286 } 287 288 hr = region_at(last); 289 // If we cannot fit a filler object, we must set top to the end 290 // of the humongous object, otherwise we cannot iterate the heap 291 // and the BOT will not be complete. 292 hr->set_top(hr->end() - words_not_fillable); 293 294 assert(hr->bottom() < obj_top && obj_top <= hr->end(), 295 "obj_top should be in last region"); 296 297 assert(words_not_fillable == 0 || 298 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(), 299 "Miscalculation in humongous allocation"); 300 301 increase_used((word_size_sum - words_not_fillable) * HeapWordSize); 302 303 for (uint i = first; i <= last; ++i) { 304 hr = region_at(i); 305 _humongous_set.add(hr); 306 _hr_printer.alloc(hr); 307 } 308 309 return new_obj; 310 } 311 312 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) { 313 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size); 314 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords; 315 } 316 317 // If could fit into free regions w/o expansion, try. 318 // Otherwise, if can expand, do so. 319 // Otherwise, if using ex regions might help, try with ex given back. 320 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) { 321 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 322 323 _verifier->verify_region_sets_optional(); 324 325 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size); 326 327 // Policy: First try to allocate a humongous object in the free list. 328 HeapRegion* humongous_start = _hrm.allocate_humongous(obj_regions); 329 if (humongous_start == NULL) { 330 // Policy: We could not find enough regions for the humongous object in the 331 // free list. Look through the heap to find a mix of free and uncommitted regions. 332 // If so, expand the heap and allocate the humongous object. 333 humongous_start = _hrm.expand_and_allocate_humongous(obj_regions); 334 if (humongous_start != NULL) { 335 // We managed to find a region by expanding the heap. 336 log_debug(gc, ergo, heap)("Heap expansion (humongous allocation request). Allocation request: " SIZE_FORMAT "B", 337 word_size * HeapWordSize); 338 policy()->record_new_heap_size(num_regions()); 339 } else { 340 // Policy: Potentially trigger a defragmentation GC. 341 } 342 } 343 344 HeapWord* result = NULL; 345 if (humongous_start != NULL) { 346 result = humongous_obj_allocate_initialize_regions(humongous_start, obj_regions, word_size); 347 assert(result != NULL, "it should always return a valid result"); 348 349 // A successful humongous object allocation changes the used space 350 // information of the old generation so we need to recalculate the 351 // sizes and update the jstat counters here. 352 monitoring_support()->update_sizes(); 353 } 354 355 _verifier->verify_region_sets_optional(); 356 357 return result; 358 } 359 360 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size, 361 size_t requested_size, 362 size_t* actual_size) { 363 assert_heap_not_locked_and_not_at_safepoint(); 364 assert(!is_humongous(requested_size), "we do not allow humongous TLABs"); 365 366 return attempt_allocation(min_size, requested_size, actual_size); 367 } 368 369 HeapWord* 370 G1CollectedHeap::mem_allocate(size_t word_size, 371 bool* gc_overhead_limit_was_exceeded) { 372 assert_heap_not_locked_and_not_at_safepoint(); 373 374 if (is_humongous(word_size)) { 375 return attempt_allocation_humongous(word_size); 376 } 377 size_t dummy = 0; 378 return attempt_allocation(word_size, word_size, &dummy); 379 } 380 381 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) { 382 ResourceMark rm; // For retrieving the thread names in log messages. 383 384 // Make sure you read the note in attempt_allocation_humongous(). 385 386 assert_heap_not_locked_and_not_at_safepoint(); 387 assert(!is_humongous(word_size), "attempt_allocation_slow() should not " 388 "be called for humongous allocation requests"); 389 390 // We should only get here after the first-level allocation attempt 391 // (attempt_allocation()) failed to allocate. 392 393 // We will loop until a) we manage to successfully perform the 394 // allocation or b) we successfully schedule a collection which 395 // fails to perform the allocation. b) is the only case when we'll 396 // return NULL. 397 HeapWord* result = NULL; 398 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 399 bool should_try_gc; 400 uint gc_count_before; 401 402 { 403 MutexLocker x(Heap_lock); 404 405 // Now that we have the lock, we first retry the allocation in case another 406 // thread changed the region while we were waiting to acquire the lock. 407 result = _allocator->attempt_allocation_locked(word_size); 408 if (result != NULL) { 409 return result; 410 } 411 412 // If the GCLocker is active and we are bound for a GC, try expanding young gen. 413 // This is different to when only GCLocker::needs_gc() is set: try to avoid 414 // waiting because the GCLocker is active to not wait too long. 415 if (GCLocker::is_active_and_needs_gc() && policy()->can_expand_young_list()) { 416 // No need for an ergo message here, can_expand_young_list() does this when 417 // it returns true. 418 result = _allocator->attempt_allocation_force(word_size); 419 if (result != NULL) { 420 return result; 421 } 422 } 423 424 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until 425 // the GCLocker initiated GC has been performed and then retry. This includes 426 // the case when the GC Locker is not active but has not been performed. 427 should_try_gc = !GCLocker::needs_gc(); 428 // Read the GC count while still holding the Heap_lock. 429 gc_count_before = total_collections(); 430 } 431 432 if (should_try_gc) { 433 bool succeeded; 434 result = do_collection_pause(word_size, gc_count_before, &succeeded, GCCause::_g1_inc_collection_pause); 435 if (result != NULL) { 436 assert(succeeded, "only way to get back a non-NULL result"); 437 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT, 438 Thread::current()->name(), p2i(result)); 439 return result; 440 } 441 442 if (succeeded) { 443 // We successfully scheduled a collection which failed to allocate. No 444 // point in trying to allocate further. We'll just return NULL. 445 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate " 446 SIZE_FORMAT " words", Thread::current()->name(), word_size); 447 return NULL; 448 } 449 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words", 450 Thread::current()->name(), word_size); 451 } else { 452 // Failed to schedule a collection. 453 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 454 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating " 455 SIZE_FORMAT " words", Thread::current()->name(), word_size); 456 return NULL; 457 } 458 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name()); 459 // The GCLocker is either active or the GCLocker initiated 460 // GC has not yet been performed. Stall until it is and 461 // then retry the allocation. 462 GCLocker::stall_until_clear(); 463 gclocker_retry_count += 1; 464 } 465 466 // We can reach here if we were unsuccessful in scheduling a 467 // collection (because another thread beat us to it) or if we were 468 // stalled due to the GC locker. In either can we should retry the 469 // allocation attempt in case another thread successfully 470 // performed a collection and reclaimed enough space. We do the 471 // first attempt (without holding the Heap_lock) here and the 472 // follow-on attempt will be at the start of the next loop 473 // iteration (after taking the Heap_lock). 474 size_t dummy = 0; 475 result = _allocator->attempt_allocation(word_size, word_size, &dummy); 476 if (result != NULL) { 477 return result; 478 } 479 480 // Give a warning if we seem to be looping forever. 481 if ((QueuedAllocationWarningCount > 0) && 482 (try_count % QueuedAllocationWarningCount == 0)) { 483 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words", 484 Thread::current()->name(), try_count, word_size); 485 } 486 } 487 488 ShouldNotReachHere(); 489 return NULL; 490 } 491 492 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) { 493 assert(ranges != NULL, "MemRegion array NULL"); 494 assert(count != 0, "No MemRegions provided"); 495 MemRegion reserved = _hrm.reserved(); 496 for (size_t i = 0; i < count; i++) { 497 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) { 498 return false; 499 } 500 } 501 return true; 502 } 503 504 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, 505 size_t count, 506 bool open) { 507 assert(!is_init_completed(), "Expect to be called at JVM init time"); 508 assert(ranges != NULL, "MemRegion array NULL"); 509 assert(count != 0, "No MemRegions provided"); 510 MutexLocker x(Heap_lock); 511 512 MemRegion reserved = _hrm.reserved(); 513 HeapWord* prev_last_addr = NULL; 514 HeapRegion* prev_last_region = NULL; 515 516 // Temporarily disable pretouching of heap pages. This interface is used 517 // when mmap'ing archived heap data in, so pre-touching is wasted. 518 FlagSetting fs(AlwaysPreTouch, false); 519 520 // For each specified MemRegion range, allocate the corresponding G1 521 // regions and mark them as archive regions. We expect the ranges 522 // in ascending starting address order, without overlap. 523 for (size_t i = 0; i < count; i++) { 524 MemRegion curr_range = ranges[i]; 525 HeapWord* start_address = curr_range.start(); 526 size_t word_size = curr_range.word_size(); 527 HeapWord* last_address = curr_range.last(); 528 size_t commits = 0; 529 530 guarantee(reserved.contains(start_address) && reserved.contains(last_address), 531 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 532 p2i(start_address), p2i(last_address)); 533 guarantee(start_address > prev_last_addr, 534 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 535 p2i(start_address), p2i(prev_last_addr)); 536 prev_last_addr = last_address; 537 538 // Check for ranges that start in the same G1 region in which the previous 539 // range ended, and adjust the start address so we don't try to allocate 540 // the same region again. If the current range is entirely within that 541 // region, skip it, just adjusting the recorded top. 542 HeapRegion* start_region = _hrm.addr_to_region(start_address); 543 if ((prev_last_region != NULL) && (start_region == prev_last_region)) { 544 start_address = start_region->end(); 545 if (start_address > last_address) { 546 increase_used(word_size * HeapWordSize); 547 start_region->set_top(last_address + 1); 548 continue; 549 } 550 start_region->set_top(start_address); 551 curr_range = MemRegion(start_address, last_address + 1); 552 start_region = _hrm.addr_to_region(start_address); 553 } 554 555 // Perform the actual region allocation, exiting if it fails. 556 // Then note how much new space we have allocated. 557 if (!_hrm.allocate_containing_regions(curr_range, &commits, workers())) { 558 return false; 559 } 560 increase_used(word_size * HeapWordSize); 561 if (commits != 0) { 562 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B", 563 HeapRegion::GrainWords * HeapWordSize * commits); 564 565 } 566 567 // Mark each G1 region touched by the range as archive, add it to 568 // the old set, and set top. 569 HeapRegion* curr_region = _hrm.addr_to_region(start_address); 570 HeapRegion* last_region = _hrm.addr_to_region(last_address); 571 prev_last_region = last_region; 572 573 while (curr_region != NULL) { 574 assert(curr_region->is_empty() && !curr_region->is_pinned(), 575 "Region already in use (index %u)", curr_region->hrm_index()); 576 if (open) { 577 curr_region->set_open_archive(); 578 } else { 579 curr_region->set_closed_archive(); 580 } 581 _hr_printer.alloc(curr_region); 582 _archive_set.add(curr_region); 583 HeapWord* top; 584 HeapRegion* next_region; 585 if (curr_region != last_region) { 586 top = curr_region->end(); 587 next_region = _hrm.next_region_in_heap(curr_region); 588 } else { 589 top = last_address + 1; 590 next_region = NULL; 591 } 592 curr_region->set_top(top); 593 curr_region = next_region; 594 } 595 } 596 return true; 597 } 598 599 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) { 600 assert(!is_init_completed(), "Expect to be called at JVM init time"); 601 assert(ranges != NULL, "MemRegion array NULL"); 602 assert(count != 0, "No MemRegions provided"); 603 MemRegion reserved = _hrm.reserved(); 604 HeapWord *prev_last_addr = NULL; 605 HeapRegion* prev_last_region = NULL; 606 607 // For each MemRegion, create filler objects, if needed, in the G1 regions 608 // that contain the address range. The address range actually within the 609 // MemRegion will not be modified. That is assumed to have been initialized 610 // elsewhere, probably via an mmap of archived heap data. 611 MutexLocker x(Heap_lock); 612 for (size_t i = 0; i < count; i++) { 613 HeapWord* start_address = ranges[i].start(); 614 HeapWord* last_address = ranges[i].last(); 615 616 assert(reserved.contains(start_address) && reserved.contains(last_address), 617 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 618 p2i(start_address), p2i(last_address)); 619 assert(start_address > prev_last_addr, 620 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 621 p2i(start_address), p2i(prev_last_addr)); 622 623 HeapRegion* start_region = _hrm.addr_to_region(start_address); 624 HeapRegion* last_region = _hrm.addr_to_region(last_address); 625 HeapWord* bottom_address = start_region->bottom(); 626 627 // Check for a range beginning in the same region in which the 628 // previous one ended. 629 if (start_region == prev_last_region) { 630 bottom_address = prev_last_addr + 1; 631 } 632 633 // Verify that the regions were all marked as archive regions by 634 // alloc_archive_regions. 635 HeapRegion* curr_region = start_region; 636 while (curr_region != NULL) { 637 guarantee(curr_region->is_archive(), 638 "Expected archive region at index %u", curr_region->hrm_index()); 639 if (curr_region != last_region) { 640 curr_region = _hrm.next_region_in_heap(curr_region); 641 } else { 642 curr_region = NULL; 643 } 644 } 645 646 prev_last_addr = last_address; 647 prev_last_region = last_region; 648 649 // Fill the memory below the allocated range with dummy object(s), 650 // if the region bottom does not match the range start, or if the previous 651 // range ended within the same G1 region, and there is a gap. 652 assert(start_address >= bottom_address, "bottom address should not be greater than start address"); 653 if (start_address > bottom_address) { 654 size_t fill_size = pointer_delta(start_address, bottom_address); 655 G1CollectedHeap::fill_with_objects(bottom_address, fill_size); 656 increase_used(fill_size * HeapWordSize); 657 } 658 } 659 } 660 661 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size, 662 size_t desired_word_size, 663 size_t* actual_word_size) { 664 assert_heap_not_locked_and_not_at_safepoint(); 665 assert(!is_humongous(desired_word_size), "attempt_allocation() should not " 666 "be called for humongous allocation requests"); 667 668 HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size); 669 670 if (result == NULL) { 671 *actual_word_size = desired_word_size; 672 result = attempt_allocation_slow(desired_word_size); 673 } 674 675 assert_heap_not_locked(); 676 if (result != NULL) { 677 assert(*actual_word_size != 0, "Actual size must have been set here"); 678 dirty_young_block(result, *actual_word_size); 679 } else { 680 *actual_word_size = 0; 681 } 682 683 return result; 684 } 685 686 void G1CollectedHeap::populate_archive_regions_bot_part(MemRegion* ranges, size_t count) { 687 assert(!is_init_completed(), "Expect to be called at JVM init time"); 688 assert(ranges != NULL, "MemRegion array NULL"); 689 assert(count != 0, "No MemRegions provided"); 690 691 HeapWord* st = ranges[0].start(); 692 HeapWord* last = ranges[count-1].last(); 693 HeapRegion* hr_st = _hrm.addr_to_region(st); 694 HeapRegion* hr_last = _hrm.addr_to_region(last); 695 696 HeapRegion* hr_curr = hr_st; 697 while (hr_curr != NULL) { 698 hr_curr->update_bot(); 699 if (hr_curr != hr_last) { 700 hr_curr = _hrm.next_region_in_heap(hr_curr); 701 } else { 702 hr_curr = NULL; 703 } 704 } 705 } 706 707 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) { 708 assert(!is_init_completed(), "Expect to be called at JVM init time"); 709 assert(ranges != NULL, "MemRegion array NULL"); 710 assert(count != 0, "No MemRegions provided"); 711 MemRegion reserved = _hrm.reserved(); 712 HeapWord* prev_last_addr = NULL; 713 HeapRegion* prev_last_region = NULL; 714 size_t size_used = 0; 715 uint shrink_count = 0; 716 717 // For each Memregion, free the G1 regions that constitute it, and 718 // notify mark-sweep that the range is no longer to be considered 'archive.' 719 MutexLocker x(Heap_lock); 720 for (size_t i = 0; i < count; i++) { 721 HeapWord* start_address = ranges[i].start(); 722 HeapWord* last_address = ranges[i].last(); 723 724 assert(reserved.contains(start_address) && reserved.contains(last_address), 725 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 726 p2i(start_address), p2i(last_address)); 727 assert(start_address > prev_last_addr, 728 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 729 p2i(start_address), p2i(prev_last_addr)); 730 size_used += ranges[i].byte_size(); 731 prev_last_addr = last_address; 732 733 HeapRegion* start_region = _hrm.addr_to_region(start_address); 734 HeapRegion* last_region = _hrm.addr_to_region(last_address); 735 736 // Check for ranges that start in the same G1 region in which the previous 737 // range ended, and adjust the start address so we don't try to free 738 // the same region again. If the current range is entirely within that 739 // region, skip it. 740 if (start_region == prev_last_region) { 741 start_address = start_region->end(); 742 if (start_address > last_address) { 743 continue; 744 } 745 start_region = _hrm.addr_to_region(start_address); 746 } 747 prev_last_region = last_region; 748 749 // After verifying that each region was marked as an archive region by 750 // alloc_archive_regions, set it free and empty and uncommit it. 751 HeapRegion* curr_region = start_region; 752 while (curr_region != NULL) { 753 guarantee(curr_region->is_archive(), 754 "Expected archive region at index %u", curr_region->hrm_index()); 755 uint curr_index = curr_region->hrm_index(); 756 _archive_set.remove(curr_region); 757 curr_region->set_free(); 758 curr_region->set_top(curr_region->bottom()); 759 if (curr_region != last_region) { 760 curr_region = _hrm.next_region_in_heap(curr_region); 761 } else { 762 curr_region = NULL; 763 } 764 765 _hrm.shrink_at(curr_index, 1); 766 shrink_count++; 767 } 768 } 769 770 if (shrink_count != 0) { 771 log_debug(gc, ergo, heap)("Attempt heap shrinking (archive regions). Total size: " SIZE_FORMAT "B", 772 HeapRegion::GrainWords * HeapWordSize * shrink_count); 773 // Explicit uncommit. 774 uncommit_regions(shrink_count); 775 } 776 decrease_used(size_used); 777 } 778 779 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) { 780 ResourceMark rm; // For retrieving the thread names in log messages. 781 782 // The structure of this method has a lot of similarities to 783 // attempt_allocation_slow(). The reason these two were not merged 784 // into a single one is that such a method would require several "if 785 // allocation is not humongous do this, otherwise do that" 786 // conditional paths which would obscure its flow. In fact, an early 787 // version of this code did use a unified method which was harder to 788 // follow and, as a result, it had subtle bugs that were hard to 789 // track down. So keeping these two methods separate allows each to 790 // be more readable. It will be good to keep these two in sync as 791 // much as possible. 792 793 assert_heap_not_locked_and_not_at_safepoint(); 794 assert(is_humongous(word_size), "attempt_allocation_humongous() " 795 "should only be called for humongous allocations"); 796 797 // Humongous objects can exhaust the heap quickly, so we should check if we 798 // need to start a marking cycle at each humongous object allocation. We do 799 // the check before we do the actual allocation. The reason for doing it 800 // before the allocation is that we avoid having to keep track of the newly 801 // allocated memory while we do a GC. 802 if (policy()->need_to_start_conc_mark("concurrent humongous allocation", 803 word_size)) { 804 collect(GCCause::_g1_humongous_allocation); 805 } 806 807 // We will loop until a) we manage to successfully perform the 808 // allocation or b) we successfully schedule a collection which 809 // fails to perform the allocation. b) is the only case when we'll 810 // return NULL. 811 HeapWord* result = NULL; 812 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 813 bool should_try_gc; 814 uint gc_count_before; 815 816 817 { 818 MutexLocker x(Heap_lock); 819 820 size_t size_in_regions = humongous_obj_size_in_regions(word_size); 821 // Given that humongous objects are not allocated in young 822 // regions, we'll first try to do the allocation without doing a 823 // collection hoping that there's enough space in the heap. 824 result = humongous_obj_allocate(word_size); 825 if (result != NULL) { 826 policy()->old_gen_alloc_tracker()-> 827 add_allocated_humongous_bytes_since_last_gc(size_in_regions * HeapRegion::GrainBytes); 828 return result; 829 } 830 831 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until 832 // the GCLocker initiated GC has been performed and then retry. This includes 833 // the case when the GC Locker is not active but has not been performed. 834 should_try_gc = !GCLocker::needs_gc(); 835 // Read the GC count while still holding the Heap_lock. 836 gc_count_before = total_collections(); 837 } 838 839 if (should_try_gc) { 840 bool succeeded; 841 result = do_collection_pause(word_size, gc_count_before, &succeeded, GCCause::_g1_humongous_allocation); 842 if (result != NULL) { 843 assert(succeeded, "only way to get back a non-NULL result"); 844 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT, 845 Thread::current()->name(), p2i(result)); 846 size_t size_in_regions = humongous_obj_size_in_regions(word_size); 847 policy()->old_gen_alloc_tracker()-> 848 record_collection_pause_humongous_allocation(size_in_regions * HeapRegion::GrainBytes); 849 return result; 850 } 851 852 if (succeeded) { 853 // We successfully scheduled a collection which failed to allocate. No 854 // point in trying to allocate further. We'll just return NULL. 855 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate " 856 SIZE_FORMAT " words", Thread::current()->name(), word_size); 857 return NULL; 858 } 859 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "", 860 Thread::current()->name(), word_size); 861 } else { 862 // Failed to schedule a collection. 863 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 864 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating " 865 SIZE_FORMAT " words", Thread::current()->name(), word_size); 866 return NULL; 867 } 868 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name()); 869 // The GCLocker is either active or the GCLocker initiated 870 // GC has not yet been performed. Stall until it is and 871 // then retry the allocation. 872 GCLocker::stall_until_clear(); 873 gclocker_retry_count += 1; 874 } 875 876 877 // We can reach here if we were unsuccessful in scheduling a 878 // collection (because another thread beat us to it) or if we were 879 // stalled due to the GC locker. In either can we should retry the 880 // allocation attempt in case another thread successfully 881 // performed a collection and reclaimed enough space. 882 // Humongous object allocation always needs a lock, so we wait for the retry 883 // in the next iteration of the loop, unlike for the regular iteration case. 884 // Give a warning if we seem to be looping forever. 885 886 if ((QueuedAllocationWarningCount > 0) && 887 (try_count % QueuedAllocationWarningCount == 0)) { 888 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words", 889 Thread::current()->name(), try_count, word_size); 890 } 891 } 892 893 ShouldNotReachHere(); 894 return NULL; 895 } 896 897 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size, 898 bool expect_null_mutator_alloc_region) { 899 assert_at_safepoint_on_vm_thread(); 900 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region, 901 "the current alloc region was unexpectedly found to be non-NULL"); 902 903 if (!is_humongous(word_size)) { 904 return _allocator->attempt_allocation_locked(word_size); 905 } else { 906 HeapWord* result = humongous_obj_allocate(word_size); 907 if (result != NULL && policy()->need_to_start_conc_mark("STW humongous allocation")) { 908 collector_state()->set_initiate_conc_mark_if_possible(true); 909 } 910 return result; 911 } 912 913 ShouldNotReachHere(); 914 } 915 916 class PostCompactionPrinterClosure: public HeapRegionClosure { 917 private: 918 G1HRPrinter* _hr_printer; 919 public: 920 bool do_heap_region(HeapRegion* hr) { 921 assert(!hr->is_young(), "not expecting to find young regions"); 922 _hr_printer->post_compaction(hr); 923 return false; 924 } 925 926 PostCompactionPrinterClosure(G1HRPrinter* hr_printer) 927 : _hr_printer(hr_printer) { } 928 }; 929 930 void G1CollectedHeap::print_heap_after_full_collection() { 931 // Post collection region logging. 932 // We should do this after we potentially resize the heap so 933 // that all the COMMIT / UNCOMMIT events are generated before 934 // the compaction events. 935 if (_hr_printer.is_active()) { 936 PostCompactionPrinterClosure cl(hr_printer()); 937 heap_region_iterate(&cl); 938 } 939 } 940 941 bool G1CollectedHeap::abort_concurrent_cycle() { 942 // Disable discovery and empty the discovered lists 943 // for the CM ref processor. 944 _ref_processor_cm->disable_discovery(); 945 _ref_processor_cm->abandon_partial_discovery(); 946 _ref_processor_cm->verify_no_references_recorded(); 947 948 // Abandon current iterations of concurrent marking and concurrent 949 // refinement, if any are in progress. 950 return concurrent_mark()->concurrent_cycle_abort(); 951 } 952 953 void G1CollectedHeap::prepare_heap_for_full_collection() { 954 // Make sure we'll choose a new allocation region afterwards. 955 _allocator->release_mutator_alloc_regions(); 956 _allocator->abandon_gc_alloc_regions(); 957 958 // We may have added regions to the current incremental collection 959 // set between the last GC or pause and now. We need to clear the 960 // incremental collection set and then start rebuilding it afresh 961 // after this full GC. 962 abandon_collection_set(collection_set()); 963 964 _hrm.remove_all_free_regions(); 965 } 966 967 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) { 968 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant"); 969 assert_used_and_recalculate_used_equal(this); 970 if (!VerifyBeforeGC) { 971 return; 972 } 973 _verifier->verify_region_sets_optional(); 974 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull); 975 _verifier->verify_bitmap_clear(true /* above_tams_only */); 976 } 977 978 void G1CollectedHeap::prepare_for_mutator_after_full_collection() { 979 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 980 ClassLoaderDataGraph::purge(/*at_safepoint*/true); 981 DEBUG_ONLY(MetaspaceUtils::verify();) 982 983 // Prepare heap for normal collections. 984 assert(num_free_regions() == 0, "we should not have added any free regions"); 985 rebuild_region_sets(false /* free_list_only */); 986 abort_refinement(); 987 resize_heap_if_necessary(); 988 uncommit_regions_if_necessary(); 989 990 // Rebuild the code root lists for each region 991 rebuild_code_roots(); 992 993 start_new_collection_set(); 994 _allocator->init_mutator_alloc_regions(); 995 996 // Post collection state updates. 997 MetaspaceGC::compute_new_size(); 998 } 999 1000 void G1CollectedHeap::abort_refinement() { 1001 // Discard all remembered set updates and reset refinement statistics. 1002 G1BarrierSet::dirty_card_queue_set().abandon_logs_and_stats(); 1003 assert(G1BarrierSet::dirty_card_queue_set().num_cards() == 0, 1004 "DCQS should be empty"); 1005 concurrent_refine()->get_and_reset_refinement_stats(); 1006 } 1007 1008 void G1CollectedHeap::verify_after_full_collection() { 1009 if (!VerifyAfterGC) { 1010 return; 1011 } 1012 _hrm.verify_optional(); 1013 _verifier->verify_region_sets_optional(); 1014 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull); 1015 _verifier->verify_bitmap_clear(false /* above_tams_only */); 1016 1017 // At this point there should be no regions in the 1018 // entire heap tagged as young. 1019 assert(check_young_list_empty(), "young list should be empty at this point"); 1020 1021 // Note: since we've just done a full GC, concurrent 1022 // marking is no longer active. Therefore we need not 1023 // re-enable reference discovery for the CM ref processor. 1024 // That will be done at the start of the next marking cycle. 1025 // We also know that the STW processor should no longer 1026 // discover any new references. 1027 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition"); 1028 assert(!_ref_processor_cm->discovery_enabled(), "Postcondition"); 1029 _ref_processor_stw->verify_no_references_recorded(); 1030 _ref_processor_cm->verify_no_references_recorded(); 1031 } 1032 1033 bool G1CollectedHeap::do_full_collection(bool explicit_gc, 1034 bool clear_all_soft_refs, 1035 bool do_maximal_compaction) { 1036 assert_at_safepoint_on_vm_thread(); 1037 1038 if (GCLocker::check_active_before_gc()) { 1039 // Full GC was not completed. 1040 return false; 1041 } 1042 1043 const bool do_clear_all_soft_refs = clear_all_soft_refs || 1044 soft_ref_policy()->should_clear_all_soft_refs(); 1045 1046 G1FullGCMark gc_mark; 1047 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true); 1048 G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs, do_maximal_compaction, gc_mark.tracer()); 1049 1050 collector.prepare_collection(); 1051 collector.collect(); 1052 collector.complete_collection(); 1053 1054 // Full collection was successfully completed. 1055 return true; 1056 } 1057 1058 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) { 1059 // Currently, there is no facility in the do_full_collection(bool) API to notify 1060 // the caller that the collection did not succeed (e.g., because it was locked 1061 // out by the GC locker). So, right now, we'll ignore the return value. 1062 // When clear_all_soft_refs is set we want to do a maximal compaction 1063 // not leaving any dead wood. 1064 bool do_maximal_compaction = clear_all_soft_refs; 1065 bool dummy = do_full_collection(true, /* explicit_gc */ 1066 clear_all_soft_refs, 1067 do_maximal_compaction); 1068 } 1069 1070 bool G1CollectedHeap::upgrade_to_full_collection() { 1071 GCCauseSetter compaction(this, GCCause::_g1_compaction_pause); 1072 log_info(gc, ergo)("Attempting full compaction clearing soft references"); 1073 bool success = do_full_collection(false /* explicit gc */, 1074 true /* clear_all_soft_refs */, 1075 false /* do_maximal_compaction */); 1076 // do_full_collection only fails if blocked by GC locker and that can't 1077 // be the case here since we only call this when already completed one gc. 1078 assert(success, "invariant"); 1079 return success; 1080 } 1081 1082 void G1CollectedHeap::resize_heap_if_necessary() { 1083 assert_at_safepoint_on_vm_thread(); 1084 1085 bool should_expand; 1086 size_t resize_amount = _heap_sizing_policy->full_collection_resize_amount(should_expand); 1087 1088 if (resize_amount == 0) { 1089 return; 1090 } else if (should_expand) { 1091 expand(resize_amount, _workers); 1092 } else { 1093 shrink(resize_amount); 1094 } 1095 } 1096 1097 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size, 1098 bool do_gc, 1099 bool maximal_compaction, 1100 bool expect_null_mutator_alloc_region, 1101 bool* gc_succeeded) { 1102 *gc_succeeded = true; 1103 // Let's attempt the allocation first. 1104 HeapWord* result = 1105 attempt_allocation_at_safepoint(word_size, 1106 expect_null_mutator_alloc_region); 1107 if (result != NULL) { 1108 return result; 1109 } 1110 1111 // In a G1 heap, we're supposed to keep allocation from failing by 1112 // incremental pauses. Therefore, at least for now, we'll favor 1113 // expansion over collection. (This might change in the future if we can 1114 // do something smarter than full collection to satisfy a failed alloc.) 1115 result = expand_and_allocate(word_size); 1116 if (result != NULL) { 1117 return result; 1118 } 1119 1120 if (do_gc) { 1121 GCCauseSetter compaction(this, GCCause::_g1_compaction_pause); 1122 // Expansion didn't work, we'll try to do a Full GC. 1123 // If maximal_compaction is set we clear all soft references and don't 1124 // allow any dead wood to be left on the heap. 1125 if (maximal_compaction) { 1126 log_info(gc, ergo)("Attempting maximal full compaction clearing soft references"); 1127 } else { 1128 log_info(gc, ergo)("Attempting full compaction"); 1129 } 1130 *gc_succeeded = do_full_collection(false, /* explicit_gc */ 1131 maximal_compaction /* clear_all_soft_refs */ , 1132 maximal_compaction /* do_maximal_compaction */); 1133 } 1134 1135 return NULL; 1136 } 1137 1138 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size, 1139 bool* succeeded) { 1140 assert_at_safepoint_on_vm_thread(); 1141 1142 // Attempts to allocate followed by Full GC. 1143 HeapWord* result = 1144 satisfy_failed_allocation_helper(word_size, 1145 true, /* do_gc */ 1146 false, /* maximum_collection */ 1147 false, /* expect_null_mutator_alloc_region */ 1148 succeeded); 1149 1150 if (result != NULL || !*succeeded) { 1151 return result; 1152 } 1153 1154 // Attempts to allocate followed by Full GC that will collect all soft references. 1155 result = satisfy_failed_allocation_helper(word_size, 1156 true, /* do_gc */ 1157 true, /* maximum_collection */ 1158 true, /* expect_null_mutator_alloc_region */ 1159 succeeded); 1160 1161 if (result != NULL || !*succeeded) { 1162 return result; 1163 } 1164 1165 // Attempts to allocate, no GC 1166 result = satisfy_failed_allocation_helper(word_size, 1167 false, /* do_gc */ 1168 false, /* maximum_collection */ 1169 true, /* expect_null_mutator_alloc_region */ 1170 succeeded); 1171 1172 if (result != NULL) { 1173 return result; 1174 } 1175 1176 assert(!soft_ref_policy()->should_clear_all_soft_refs(), 1177 "Flag should have been handled and cleared prior to this point"); 1178 1179 // What else? We might try synchronous finalization later. If the total 1180 // space available is large enough for the allocation, then a more 1181 // complete compaction phase than we've tried so far might be 1182 // appropriate. 1183 return NULL; 1184 } 1185 1186 // Attempting to expand the heap sufficiently 1187 // to support an allocation of the given "word_size". If 1188 // successful, perform the allocation and return the address of the 1189 // allocated block, or else "NULL". 1190 1191 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) { 1192 assert_at_safepoint_on_vm_thread(); 1193 1194 _verifier->verify_region_sets_optional(); 1195 1196 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes); 1197 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B", 1198 word_size * HeapWordSize); 1199 1200 1201 if (expand(expand_bytes, _workers)) { 1202 _hrm.verify_optional(); 1203 _verifier->verify_region_sets_optional(); 1204 return attempt_allocation_at_safepoint(word_size, 1205 false /* expect_null_mutator_alloc_region */); 1206 } 1207 return NULL; 1208 } 1209 1210 bool G1CollectedHeap::expand(size_t expand_bytes, WorkerThreads* pretouch_workers, double* expand_time_ms) { 1211 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); 1212 aligned_expand_bytes = align_up(aligned_expand_bytes, 1213 HeapRegion::GrainBytes); 1214 1215 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B", 1216 expand_bytes, aligned_expand_bytes); 1217 1218 if (is_maximal_no_gc()) { 1219 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)"); 1220 return false; 1221 } 1222 1223 double expand_heap_start_time_sec = os::elapsedTime(); 1224 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes); 1225 assert(regions_to_expand > 0, "Must expand by at least one region"); 1226 1227 uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers); 1228 if (expand_time_ms != NULL) { 1229 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS; 1230 } 1231 1232 if (expanded_by > 0) { 1233 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes; 1234 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition"); 1235 policy()->record_new_heap_size(num_regions()); 1236 } else { 1237 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)"); 1238 1239 // The expansion of the virtual storage space was unsuccessful. 1240 // Let's see if it was because we ran out of swap. 1241 if (G1ExitOnExpansionFailure && 1242 _hrm.available() >= regions_to_expand) { 1243 // We had head room... 1244 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion"); 1245 } 1246 } 1247 return expanded_by > 0; 1248 } 1249 1250 bool G1CollectedHeap::expand_single_region(uint node_index) { 1251 uint expanded_by = _hrm.expand_on_preferred_node(node_index); 1252 1253 if (expanded_by == 0) { 1254 assert(is_maximal_no_gc(), "Should be no regions left, available: %u", _hrm.available()); 1255 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)"); 1256 return false; 1257 } 1258 1259 policy()->record_new_heap_size(num_regions()); 1260 return true; 1261 } 1262 1263 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) { 1264 size_t aligned_shrink_bytes = 1265 ReservedSpace::page_align_size_down(shrink_bytes); 1266 aligned_shrink_bytes = align_down(aligned_shrink_bytes, 1267 HeapRegion::GrainBytes); 1268 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes); 1269 1270 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove); 1271 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes; 1272 1273 log_debug(gc, ergo, heap)("Shrink the heap. requested shrinking amount: " SIZE_FORMAT "B aligned shrinking amount: " SIZE_FORMAT "B actual amount shrunk: " SIZE_FORMAT "B", 1274 shrink_bytes, aligned_shrink_bytes, shrunk_bytes); 1275 if (num_regions_removed > 0) { 1276 log_debug(gc, heap)("Uncommittable regions after shrink: %u", num_regions_removed); 1277 policy()->record_new_heap_size(num_regions()); 1278 } else { 1279 log_debug(gc, ergo, heap)("Did not shrink the heap (heap shrinking operation failed)"); 1280 } 1281 } 1282 1283 void G1CollectedHeap::shrink(size_t shrink_bytes) { 1284 _verifier->verify_region_sets_optional(); 1285 1286 // We should only reach here at the end of a Full GC or during Remark which 1287 // means we should not not be holding to any GC alloc regions. The method 1288 // below will make sure of that and do any remaining clean up. 1289 _allocator->abandon_gc_alloc_regions(); 1290 1291 // Instead of tearing down / rebuilding the free lists here, we 1292 // could instead use the remove_all_pending() method on free_list to 1293 // remove only the ones that we need to remove. 1294 _hrm.remove_all_free_regions(); 1295 shrink_helper(shrink_bytes); 1296 rebuild_region_sets(true /* free_list_only */); 1297 1298 _hrm.verify_optional(); 1299 _verifier->verify_region_sets_optional(); 1300 } 1301 1302 class OldRegionSetChecker : public HeapRegionSetChecker { 1303 public: 1304 void check_mt_safety() { 1305 // Master Old Set MT safety protocol: 1306 // (a) If we're at a safepoint, operations on the master old set 1307 // should be invoked: 1308 // - by the VM thread (which will serialize them), or 1309 // - by the GC workers while holding the FreeList_lock, if we're 1310 // at a safepoint for an evacuation pause (this lock is taken 1311 // anyway when an GC alloc region is retired so that a new one 1312 // is allocated from the free list), or 1313 // - by the GC workers while holding the OldSets_lock, if we're at a 1314 // safepoint for a cleanup pause. 1315 // (b) If we're not at a safepoint, operations on the master old set 1316 // should be invoked while holding the Heap_lock. 1317 1318 if (SafepointSynchronize::is_at_safepoint()) { 1319 guarantee(Thread::current()->is_VM_thread() || 1320 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(), 1321 "master old set MT safety protocol at a safepoint"); 1322 } else { 1323 guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint"); 1324 } 1325 } 1326 bool is_correct_type(HeapRegion* hr) { return hr->is_old(); } 1327 const char* get_description() { return "Old Regions"; } 1328 }; 1329 1330 class ArchiveRegionSetChecker : public HeapRegionSetChecker { 1331 public: 1332 void check_mt_safety() { 1333 guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(), 1334 "May only change archive regions during initialization or safepoint."); 1335 } 1336 bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); } 1337 const char* get_description() { return "Archive Regions"; } 1338 }; 1339 1340 class HumongousRegionSetChecker : public HeapRegionSetChecker { 1341 public: 1342 void check_mt_safety() { 1343 // Humongous Set MT safety protocol: 1344 // (a) If we're at a safepoint, operations on the master humongous 1345 // set should be invoked by either the VM thread (which will 1346 // serialize them) or by the GC workers while holding the 1347 // OldSets_lock. 1348 // (b) If we're not at a safepoint, operations on the master 1349 // humongous set should be invoked while holding the Heap_lock. 1350 1351 if (SafepointSynchronize::is_at_safepoint()) { 1352 guarantee(Thread::current()->is_VM_thread() || 1353 OldSets_lock->owned_by_self(), 1354 "master humongous set MT safety protocol at a safepoint"); 1355 } else { 1356 guarantee(Heap_lock->owned_by_self(), 1357 "master humongous set MT safety protocol outside a safepoint"); 1358 } 1359 } 1360 bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); } 1361 const char* get_description() { return "Humongous Regions"; } 1362 }; 1363 1364 G1CollectedHeap::G1CollectedHeap() : 1365 CollectedHeap(), 1366 _service_thread(NULL), 1367 _periodic_gc_task(NULL), 1368 _free_arena_memory_task(NULL), 1369 _workers(NULL), 1370 _card_table(NULL), 1371 _collection_pause_end(Ticks::now()), 1372 _soft_ref_policy(), 1373 _old_set("Old Region Set", new OldRegionSetChecker()), 1374 _archive_set("Archive Region Set", new ArchiveRegionSetChecker()), 1375 _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()), 1376 _bot(NULL), 1377 _listener(), 1378 _numa(G1NUMA::create()), 1379 _hrm(), 1380 _allocator(NULL), 1381 _evac_failure_injector(), 1382 _verifier(NULL), 1383 _summary_bytes_used(0), 1384 _bytes_used_during_gc(0), 1385 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight), 1386 _old_evac_stats("Old", OldPLABSize, PLABWeight), 1387 _monitoring_support(nullptr), 1388 _num_humongous_objects(0), 1389 _num_humongous_reclaim_candidates(0), 1390 _hr_printer(), 1391 _collector_state(), 1392 _old_marking_cycles_started(0), 1393 _old_marking_cycles_completed(0), 1394 _eden(), 1395 _survivor(), 1396 _gc_timer_stw(new STWGCTimer()), 1397 _gc_tracer_stw(new G1NewTracer()), 1398 _policy(new G1Policy(_gc_timer_stw)), 1399 _heap_sizing_policy(NULL), 1400 _collection_set(this, _policy), 1401 _rem_set(NULL), 1402 _card_set_config(), 1403 _card_set_freelist_pool(G1CardSetConfiguration::num_mem_object_types()), 1404 _cm(NULL), 1405 _cm_thread(NULL), 1406 _cr(NULL), 1407 _task_queues(NULL), 1408 _ref_processor_stw(NULL), 1409 _is_alive_closure_stw(this), 1410 _is_subject_to_discovery_stw(this), 1411 _ref_processor_cm(NULL), 1412 _is_alive_closure_cm(this), 1413 _is_subject_to_discovery_cm(this), 1414 _region_attr() { 1415 1416 _verifier = new G1HeapVerifier(this); 1417 1418 _allocator = new G1Allocator(this); 1419 1420 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _policy->analytics()); 1421 1422 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords); 1423 1424 // Override the default _filler_array_max_size so that no humongous filler 1425 // objects are created. 1426 _filler_array_max_size = _humongous_object_threshold_in_words; 1427 1428 // Override the default _stack_chunk_max_size so that no humongous stack chunks are created 1429 _stack_chunk_max_size = _humongous_object_threshold_in_words; 1430 1431 uint n_queues = ParallelGCThreads; 1432 _task_queues = new G1ScannerTasksQueueSet(n_queues); 1433 1434 for (uint i = 0; i < n_queues; i++) { 1435 G1ScannerTasksQueue* q = new G1ScannerTasksQueue(); 1436 _task_queues->register_queue(i, q); 1437 } 1438 1439 _gc_tracer_stw->initialize(); 1440 1441 guarantee(_task_queues != NULL, "task_queues allocation failure."); 1442 } 1443 1444 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description, 1445 size_t size, 1446 size_t translation_factor) { 1447 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1); 1448 // Allocate a new reserved space, preferring to use large pages. 1449 ReservedSpace rs(size, preferred_page_size); 1450 size_t page_size = rs.page_size(); 1451 G1RegionToSpaceMapper* result = 1452 G1RegionToSpaceMapper::create_mapper(rs, 1453 size, 1454 page_size, 1455 HeapRegion::GrainBytes, 1456 translation_factor, 1457 mtGC); 1458 1459 os::trace_page_sizes_for_requested_size(description, 1460 size, 1461 page_size, 1462 preferred_page_size, 1463 rs.base(), 1464 rs.size()); 1465 1466 return result; 1467 } 1468 1469 jint G1CollectedHeap::initialize_concurrent_refinement() { 1470 jint ecode = JNI_OK; 1471 _cr = G1ConcurrentRefine::create(policy(), &ecode); 1472 return ecode; 1473 } 1474 1475 jint G1CollectedHeap::initialize_service_thread() { 1476 _service_thread = new G1ServiceThread(); 1477 if (_service_thread->osthread() == NULL) { 1478 vm_shutdown_during_initialization("Could not create G1ServiceThread"); 1479 return JNI_ENOMEM; 1480 } 1481 return JNI_OK; 1482 } 1483 1484 jint G1CollectedHeap::initialize() { 1485 1486 // Necessary to satisfy locking discipline assertions. 1487 1488 MutexLocker x(Heap_lock); 1489 1490 // While there are no constraints in the GC code that HeapWordSize 1491 // be any particular value, there are multiple other areas in the 1492 // system which believe this to be true (e.g. oop->object_size in some 1493 // cases incorrectly returns the size in wordSize units rather than 1494 // HeapWordSize). 1495 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 1496 1497 size_t init_byte_size = InitialHeapSize; 1498 size_t reserved_byte_size = G1Arguments::heap_reserved_size_bytes(); 1499 1500 // Ensure that the sizes are properly aligned. 1501 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1502 Universe::check_alignment(reserved_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1503 Universe::check_alignment(reserved_byte_size, HeapAlignment, "g1 heap"); 1504 1505 // Reserve the maximum. 1506 1507 // When compressed oops are enabled, the preferred heap base 1508 // is calculated by subtracting the requested size from the 1509 // 32Gb boundary and using the result as the base address for 1510 // heap reservation. If the requested size is not aligned to 1511 // HeapRegion::GrainBytes (i.e. the alignment that is passed 1512 // into the ReservedHeapSpace constructor) then the actual 1513 // base of the reserved heap may end up differing from the 1514 // address that was requested (i.e. the preferred heap base). 1515 // If this happens then we could end up using a non-optimal 1516 // compressed oops mode. 1517 1518 ReservedHeapSpace heap_rs = Universe::reserve_heap(reserved_byte_size, 1519 HeapAlignment); 1520 1521 initialize_reserved_region(heap_rs); 1522 1523 // Create the barrier set for the entire reserved region. 1524 G1CardTable* ct = new G1CardTable(heap_rs.region()); 1525 ct->initialize(); 1526 G1BarrierSet* bs = new G1BarrierSet(ct); 1527 bs->initialize(); 1528 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity"); 1529 BarrierSet::set_barrier_set(bs); 1530 _card_table = ct; 1531 1532 { 1533 G1SATBMarkQueueSet& satbqs = bs->satb_mark_queue_set(); 1534 satbqs.set_process_completed_buffers_threshold(G1SATBProcessCompletedThreshold); 1535 satbqs.set_buffer_enqueue_threshold_percentage(G1SATBBufferEnqueueingThresholdPercent); 1536 } 1537 1538 // Create space mappers. 1539 size_t page_size = heap_rs.page_size(); 1540 G1RegionToSpaceMapper* heap_storage = 1541 G1RegionToSpaceMapper::create_mapper(heap_rs, 1542 heap_rs.size(), 1543 page_size, 1544 HeapRegion::GrainBytes, 1545 1, 1546 mtJavaHeap); 1547 if(heap_storage == NULL) { 1548 vm_shutdown_during_initialization("Could not initialize G1 heap"); 1549 return JNI_ERR; 1550 } 1551 1552 os::trace_page_sizes("Heap", 1553 MinHeapSize, 1554 reserved_byte_size, 1555 page_size, 1556 heap_rs.base(), 1557 heap_rs.size()); 1558 heap_storage->set_mapping_changed_listener(&_listener); 1559 1560 // Create storage for the BOT, card table and the bitmap. 1561 G1RegionToSpaceMapper* bot_storage = 1562 create_aux_memory_mapper("Block Offset Table", 1563 G1BlockOffsetTable::compute_size(heap_rs.size() / HeapWordSize), 1564 G1BlockOffsetTable::heap_map_factor()); 1565 1566 G1RegionToSpaceMapper* cardtable_storage = 1567 create_aux_memory_mapper("Card Table", 1568 G1CardTable::compute_size(heap_rs.size() / HeapWordSize), 1569 G1CardTable::heap_map_factor()); 1570 1571 size_t bitmap_size = G1CMBitMap::compute_size(heap_rs.size()); 1572 G1RegionToSpaceMapper* bitmap_storage = 1573 create_aux_memory_mapper("Mark Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1574 1575 _hrm.initialize(heap_storage, bitmap_storage, bot_storage, cardtable_storage); 1576 _card_table->initialize(cardtable_storage); 1577 1578 // 6843694 - ensure that the maximum region index can fit 1579 // in the remembered set structures. 1580 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; 1581 guarantee((max_reserved_regions() - 1) <= max_region_idx, "too many regions"); 1582 1583 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not 1584 // start within the first card. 1585 guarantee((uintptr_t)(heap_rs.base()) >= G1CardTable::card_size(), "Java heap must not start within the first card."); 1586 G1FromCardCache::initialize(max_reserved_regions()); 1587 // Also create a G1 rem set. 1588 _rem_set = new G1RemSet(this, _card_table); 1589 _rem_set->initialize(max_reserved_regions()); 1590 1591 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; 1592 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); 1593 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region, 1594 "too many cards per region"); 1595 1596 HeapRegionRemSet::initialize(_reserved); 1597 1598 FreeRegionList::set_unrealistically_long_length(max_regions() + 1); 1599 1600 _bot = new G1BlockOffsetTable(reserved(), bot_storage); 1601 1602 { 1603 size_t granularity = HeapRegion::GrainBytes; 1604 1605 _region_attr.initialize(reserved(), granularity); 1606 } 1607 1608 _workers = new WorkerThreads("GC Thread", ParallelGCThreads); 1609 if (_workers == NULL) { 1610 return JNI_ENOMEM; 1611 } 1612 _workers->initialize_workers(); 1613 1614 _numa->set_region_info(HeapRegion::GrainBytes, page_size); 1615 1616 // Create the G1ConcurrentMark data structure and thread. 1617 // (Must do this late, so that "max_[reserved_]regions" is defined.) 1618 _cm = new G1ConcurrentMark(this, bitmap_storage); 1619 _cm_thread = _cm->cm_thread(); 1620 1621 // Now expand into the initial heap size. 1622 if (!expand(init_byte_size, _workers)) { 1623 vm_shutdown_during_initialization("Failed to allocate initial heap."); 1624 return JNI_ENOMEM; 1625 } 1626 1627 // Perform any initialization actions delegated to the policy. 1628 policy()->init(this, &_collection_set); 1629 1630 jint ecode = initialize_concurrent_refinement(); 1631 if (ecode != JNI_OK) { 1632 return ecode; 1633 } 1634 1635 ecode = initialize_service_thread(); 1636 if (ecode != JNI_OK) { 1637 return ecode; 1638 } 1639 1640 // Create and schedule the periodic gc task on the service thread. 1641 _periodic_gc_task = new G1PeriodicGCTask("Periodic GC Task"); 1642 _service_thread->register_task(_periodic_gc_task); 1643 1644 _free_arena_memory_task = new G1MonotonicArenaFreeMemoryTask("Card Set Free Memory Task"); 1645 _service_thread->register_task(_free_arena_memory_task); 1646 1647 // Here we allocate the dummy HeapRegion that is required by the 1648 // G1AllocRegion class. 1649 HeapRegion* dummy_region = _hrm.get_dummy_region(); 1650 1651 // We'll re-use the same region whether the alloc region will 1652 // require BOT updates or not and, if it doesn't, then a non-young 1653 // region will complain that it cannot support allocations without 1654 // BOT updates. So we'll tag the dummy region as eden to avoid that. 1655 dummy_region->set_eden(); 1656 // Make sure it's full. 1657 dummy_region->set_top(dummy_region->end()); 1658 G1AllocRegion::setup(this, dummy_region); 1659 1660 _allocator->init_mutator_alloc_regions(); 1661 1662 // Do create of the monitoring and management support so that 1663 // values in the heap have been properly initialized. 1664 _monitoring_support = new G1MonitoringSupport(this); 1665 1666 _collection_set.initialize(max_reserved_regions()); 1667 1668 evac_failure_injector()->reset(); 1669 1670 G1InitLogger::print(); 1671 1672 return JNI_OK; 1673 } 1674 1675 bool G1CollectedHeap::concurrent_mark_is_terminating() const { 1676 return _cm_thread->should_terminate(); 1677 } 1678 1679 void G1CollectedHeap::stop() { 1680 // Stop all concurrent threads. We do this to make sure these threads 1681 // do not continue to execute and access resources (e.g. logging) 1682 // that are destroyed during shutdown. 1683 _cr->stop(); 1684 _service_thread->stop(); 1685 _cm_thread->stop(); 1686 } 1687 1688 void G1CollectedHeap::safepoint_synchronize_begin() { 1689 SuspendibleThreadSet::synchronize(); 1690 } 1691 1692 void G1CollectedHeap::safepoint_synchronize_end() { 1693 SuspendibleThreadSet::desynchronize(); 1694 } 1695 1696 void G1CollectedHeap::post_initialize() { 1697 CollectedHeap::post_initialize(); 1698 ref_processing_init(); 1699 } 1700 1701 void G1CollectedHeap::ref_processing_init() { 1702 // Reference processing in G1 currently works as follows: 1703 // 1704 // * There are two reference processor instances. One is 1705 // used to record and process discovered references 1706 // during concurrent marking; the other is used to 1707 // record and process references during STW pauses 1708 // (both full and incremental). 1709 // * Both ref processors need to 'span' the entire heap as 1710 // the regions in the collection set may be dotted around. 1711 // 1712 // * For the concurrent marking ref processor: 1713 // * Reference discovery is enabled at concurrent start. 1714 // * Reference discovery is disabled and the discovered 1715 // references processed etc during remarking. 1716 // * Reference discovery is MT (see below). 1717 // * Reference discovery requires a barrier (see below). 1718 // * Reference processing may or may not be MT 1719 // (depending on the value of ParallelRefProcEnabled 1720 // and ParallelGCThreads). 1721 // * A full GC disables reference discovery by the CM 1722 // ref processor and abandons any entries on it's 1723 // discovered lists. 1724 // 1725 // * For the STW processor: 1726 // * Non MT discovery is enabled at the start of a full GC. 1727 // * Processing and enqueueing during a full GC is non-MT. 1728 // * During a full GC, references are processed after marking. 1729 // 1730 // * Discovery (may or may not be MT) is enabled at the start 1731 // of an incremental evacuation pause. 1732 // * References are processed near the end of a STW evacuation pause. 1733 // * For both types of GC: 1734 // * Discovery is atomic - i.e. not concurrent. 1735 // * Reference discovery will not need a barrier. 1736 1737 // Concurrent Mark ref processor 1738 _ref_processor_cm = 1739 new ReferenceProcessor(&_is_subject_to_discovery_cm, 1740 ParallelGCThreads, // degree of mt processing 1741 // We discover with the gc worker threads during Remark, so both 1742 // thread counts must be considered for discovery. 1743 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery 1744 true, // Reference discovery is concurrent 1745 &_is_alive_closure_cm); // is alive closure 1746 1747 // STW ref processor 1748 _ref_processor_stw = 1749 new ReferenceProcessor(&_is_subject_to_discovery_stw, 1750 ParallelGCThreads, // degree of mt processing 1751 ParallelGCThreads, // degree of mt discovery 1752 false, // Reference discovery is not concurrent 1753 &_is_alive_closure_stw); // is alive closure 1754 } 1755 1756 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() { 1757 return &_soft_ref_policy; 1758 } 1759 1760 size_t G1CollectedHeap::capacity() const { 1761 return _hrm.length() * HeapRegion::GrainBytes; 1762 } 1763 1764 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const { 1765 return _hrm.total_free_bytes(); 1766 } 1767 1768 // Computes the sum of the storage used by the various regions. 1769 size_t G1CollectedHeap::used() const { 1770 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions(); 1771 return result; 1772 } 1773 1774 size_t G1CollectedHeap::used_unlocked() const { 1775 return _summary_bytes_used; 1776 } 1777 1778 class SumUsedClosure: public HeapRegionClosure { 1779 size_t _used; 1780 public: 1781 SumUsedClosure() : _used(0) {} 1782 bool do_heap_region(HeapRegion* r) { 1783 _used += r->used(); 1784 return false; 1785 } 1786 size_t result() { return _used; } 1787 }; 1788 1789 size_t G1CollectedHeap::recalculate_used() const { 1790 SumUsedClosure blk; 1791 heap_region_iterate(&blk); 1792 return blk.result(); 1793 } 1794 1795 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) { 1796 return GCCause::is_user_requested_gc(cause) && ExplicitGCInvokesConcurrent; 1797 } 1798 1799 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 1800 switch (cause) { 1801 case GCCause::_g1_humongous_allocation: return true; 1802 case GCCause::_g1_periodic_collection: return G1PeriodicGCInvokesConcurrent; 1803 case GCCause::_wb_breakpoint: return true; 1804 case GCCause::_codecache_GC_aggressive: return true; 1805 case GCCause::_codecache_GC_threshold: return true; 1806 default: return is_user_requested_concurrent_full_gc(cause); 1807 } 1808 } 1809 1810 void G1CollectedHeap::increment_old_marking_cycles_started() { 1811 assert(_old_marking_cycles_started == _old_marking_cycles_completed || 1812 _old_marking_cycles_started == _old_marking_cycles_completed + 1, 1813 "Wrong marking cycle count (started: %d, completed: %d)", 1814 _old_marking_cycles_started, _old_marking_cycles_completed); 1815 1816 _old_marking_cycles_started++; 1817 } 1818 1819 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent, 1820 bool whole_heap_examined) { 1821 MonitorLocker ml(G1OldGCCount_lock, Mutex::_no_safepoint_check_flag); 1822 1823 // We assume that if concurrent == true, then the caller is a 1824 // concurrent thread that was joined the Suspendible Thread 1825 // Set. If there's ever a cheap way to check this, we should add an 1826 // assert here. 1827 1828 // Given that this method is called at the end of a Full GC or of a 1829 // concurrent cycle, and those can be nested (i.e., a Full GC can 1830 // interrupt a concurrent cycle), the number of full collections 1831 // completed should be either one (in the case where there was no 1832 // nesting) or two (when a Full GC interrupted a concurrent cycle) 1833 // behind the number of full collections started. 1834 1835 // This is the case for the inner caller, i.e. a Full GC. 1836 assert(concurrent || 1837 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || 1838 (_old_marking_cycles_started == _old_marking_cycles_completed + 2), 1839 "for inner caller (Full GC): _old_marking_cycles_started = %u " 1840 "is inconsistent with _old_marking_cycles_completed = %u", 1841 _old_marking_cycles_started, _old_marking_cycles_completed); 1842 1843 // This is the case for the outer caller, i.e. the concurrent cycle. 1844 assert(!concurrent || 1845 (_old_marking_cycles_started == _old_marking_cycles_completed + 1), 1846 "for outer caller (concurrent cycle): " 1847 "_old_marking_cycles_started = %u " 1848 "is inconsistent with _old_marking_cycles_completed = %u", 1849 _old_marking_cycles_started, _old_marking_cycles_completed); 1850 1851 _old_marking_cycles_completed += 1; 1852 if (whole_heap_examined) { 1853 // Signal that we have completed a visit to all live objects. 1854 record_whole_heap_examined_timestamp(); 1855 } 1856 1857 // We need to clear the "in_progress" flag in the CM thread before 1858 // we wake up any waiters (especially when ExplicitInvokesConcurrent 1859 // is set) so that if a waiter requests another System.gc() it doesn't 1860 // incorrectly see that a marking cycle is still in progress. 1861 if (concurrent) { 1862 _cm_thread->set_idle(); 1863 } 1864 1865 // Notify threads waiting in System.gc() (with ExplicitGCInvokesConcurrent) 1866 // for a full GC to finish that their wait is over. 1867 ml.notify_all(); 1868 } 1869 1870 // Helper for collect(). 1871 static G1GCCounters collection_counters(G1CollectedHeap* g1h) { 1872 MutexLocker ml(Heap_lock); 1873 return G1GCCounters(g1h); 1874 } 1875 1876 void G1CollectedHeap::collect(GCCause::Cause cause) { 1877 try_collect(cause, collection_counters(this)); 1878 } 1879 1880 // Return true if (x < y) with allowance for wraparound. 1881 static bool gc_counter_less_than(uint x, uint y) { 1882 return (x - y) > (UINT_MAX/2); 1883 } 1884 1885 // LOG_COLLECT_CONCURRENTLY(cause, msg, args...) 1886 // Macro so msg printing is format-checked. 1887 #define LOG_COLLECT_CONCURRENTLY(cause, ...) \ 1888 do { \ 1889 LogTarget(Trace, gc) LOG_COLLECT_CONCURRENTLY_lt; \ 1890 if (LOG_COLLECT_CONCURRENTLY_lt.is_enabled()) { \ 1891 ResourceMark rm; /* For thread name. */ \ 1892 LogStream LOG_COLLECT_CONCURRENTLY_s(&LOG_COLLECT_CONCURRENTLY_lt); \ 1893 LOG_COLLECT_CONCURRENTLY_s.print("%s: Try Collect Concurrently (%s): ", \ 1894 Thread::current()->name(), \ 1895 GCCause::to_string(cause)); \ 1896 LOG_COLLECT_CONCURRENTLY_s.print(__VA_ARGS__); \ 1897 } \ 1898 } while (0) 1899 1900 #define LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, result) \ 1901 LOG_COLLECT_CONCURRENTLY(cause, "complete %s", BOOL_TO_STR(result)) 1902 1903 bool G1CollectedHeap::try_collect_concurrently(GCCause::Cause cause, 1904 uint gc_counter, 1905 uint old_marking_started_before) { 1906 assert_heap_not_locked(); 1907 assert(should_do_concurrent_full_gc(cause), 1908 "Non-concurrent cause %s", GCCause::to_string(cause)); 1909 1910 for (uint i = 1; true; ++i) { 1911 // Try to schedule concurrent start evacuation pause that will 1912 // start a concurrent cycle. 1913 LOG_COLLECT_CONCURRENTLY(cause, "attempt %u", i); 1914 VM_G1TryInitiateConcMark op(gc_counter, cause); 1915 VMThread::execute(&op); 1916 1917 // Request is trivially finished. 1918 if (cause == GCCause::_g1_periodic_collection) { 1919 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, op.gc_succeeded()); 1920 return op.gc_succeeded(); 1921 } 1922 1923 // If VMOp skipped initiating concurrent marking cycle because 1924 // we're terminating, then we're done. 1925 if (op.terminating()) { 1926 LOG_COLLECT_CONCURRENTLY(cause, "skipped: terminating"); 1927 return false; 1928 } 1929 1930 // Lock to get consistent set of values. 1931 uint old_marking_started_after; 1932 uint old_marking_completed_after; 1933 { 1934 MutexLocker ml(Heap_lock); 1935 // Update gc_counter for retrying VMOp if needed. Captured here to be 1936 // consistent with the values we use below for termination tests. If 1937 // a retry is needed after a possible wait, and another collection 1938 // occurs in the meantime, it will cause our retry to be skipped and 1939 // we'll recheck for termination with updated conditions from that 1940 // more recent collection. That's what we want, rather than having 1941 // our retry possibly perform an unnecessary collection. 1942 gc_counter = total_collections(); 1943 old_marking_started_after = _old_marking_cycles_started; 1944 old_marking_completed_after = _old_marking_cycles_completed; 1945 } 1946 1947 if (cause == GCCause::_wb_breakpoint) { 1948 if (op.gc_succeeded()) { 1949 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true); 1950 return true; 1951 } 1952 // When _wb_breakpoint there can't be another cycle or deferred. 1953 assert(!op.cycle_already_in_progress(), "invariant"); 1954 assert(!op.whitebox_attached(), "invariant"); 1955 // Concurrent cycle attempt might have been cancelled by some other 1956 // collection, so retry. Unlike other cases below, we want to retry 1957 // even if cancelled by a STW full collection, because we really want 1958 // to start a concurrent cycle. 1959 if (old_marking_started_before != old_marking_started_after) { 1960 LOG_COLLECT_CONCURRENTLY(cause, "ignoring STW full GC"); 1961 old_marking_started_before = old_marking_started_after; 1962 } 1963 } else if (!GCCause::is_user_requested_gc(cause)) { 1964 // For an "automatic" (not user-requested) collection, we just need to 1965 // ensure that progress is made. 1966 // 1967 // Request is finished if any of 1968 // (1) the VMOp successfully performed a GC, 1969 // (2) a concurrent cycle was already in progress, 1970 // (3) whitebox is controlling concurrent cycles, 1971 // (4) a new cycle was started (by this thread or some other), or 1972 // (5) a Full GC was performed. 1973 // Cases (4) and (5) are detected together by a change to 1974 // _old_marking_cycles_started. 1975 // 1976 // Note that (1) does not imply (4). If we're still in the mixed 1977 // phase of an earlier concurrent collection, the request to make the 1978 // collection a concurrent start won't be honored. If we don't check for 1979 // both conditions we'll spin doing back-to-back collections. 1980 if (op.gc_succeeded() || 1981 op.cycle_already_in_progress() || 1982 op.whitebox_attached() || 1983 (old_marking_started_before != old_marking_started_after)) { 1984 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true); 1985 return true; 1986 } 1987 } else { // User-requested GC. 1988 // For a user-requested collection, we want to ensure that a complete 1989 // full collection has been performed before returning, but without 1990 // waiting for more than needed. 1991 1992 // For user-requested GCs (unlike non-UR), a successful VMOp implies a 1993 // new cycle was started. That's good, because it's not clear what we 1994 // should do otherwise. Trying again just does back to back GCs. 1995 // Can't wait for someone else to start a cycle. And returning fails 1996 // to meet the goal of ensuring a full collection was performed. 1997 assert(!op.gc_succeeded() || 1998 (old_marking_started_before != old_marking_started_after), 1999 "invariant: succeeded %s, started before %u, started after %u", 2000 BOOL_TO_STR(op.gc_succeeded()), 2001 old_marking_started_before, old_marking_started_after); 2002 2003 // Request is finished if a full collection (concurrent or stw) 2004 // was started after this request and has completed, e.g. 2005 // started_before < completed_after. 2006 if (gc_counter_less_than(old_marking_started_before, 2007 old_marking_completed_after)) { 2008 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true); 2009 return true; 2010 } 2011 2012 if (old_marking_started_after != old_marking_completed_after) { 2013 // If there is an in-progress cycle (possibly started by us), then 2014 // wait for that cycle to complete, e.g. 2015 // while completed_now < started_after. 2016 LOG_COLLECT_CONCURRENTLY(cause, "wait"); 2017 MonitorLocker ml(G1OldGCCount_lock); 2018 while (gc_counter_less_than(_old_marking_cycles_completed, 2019 old_marking_started_after)) { 2020 ml.wait(); 2021 } 2022 // Request is finished if the collection we just waited for was 2023 // started after this request. 2024 if (old_marking_started_before != old_marking_started_after) { 2025 LOG_COLLECT_CONCURRENTLY(cause, "complete after wait"); 2026 return true; 2027 } 2028 } 2029 2030 // If VMOp was successful then it started a new cycle that the above 2031 // wait &etc should have recognized as finishing this request. This 2032 // differs from a non-user-request, where gc_succeeded does not imply 2033 // a new cycle was started. 2034 assert(!op.gc_succeeded(), "invariant"); 2035 2036 if (op.cycle_already_in_progress()) { 2037 // If VMOp failed because a cycle was already in progress, it 2038 // is now complete. But it didn't finish this user-requested 2039 // GC, so try again. 2040 LOG_COLLECT_CONCURRENTLY(cause, "retry after in-progress"); 2041 continue; 2042 } else if (op.whitebox_attached()) { 2043 // If WhiteBox wants control, wait for notification of a state 2044 // change in the controller, then try again. Don't wait for 2045 // release of control, since collections may complete while in 2046 // control. Note: This won't recognize a STW full collection 2047 // while waiting; we can't wait on multiple monitors. 2048 LOG_COLLECT_CONCURRENTLY(cause, "whitebox control stall"); 2049 MonitorLocker ml(ConcurrentGCBreakpoints::monitor()); 2050 if (ConcurrentGCBreakpoints::is_controlled()) { 2051 ml.wait(); 2052 } 2053 continue; 2054 } 2055 } 2056 2057 // Collection failed and should be retried. 2058 assert(op.transient_failure(), "invariant"); 2059 2060 if (GCLocker::is_active_and_needs_gc()) { 2061 // If GCLocker is active, wait until clear before retrying. 2062 LOG_COLLECT_CONCURRENTLY(cause, "gc-locker stall"); 2063 GCLocker::stall_until_clear(); 2064 } 2065 2066 LOG_COLLECT_CONCURRENTLY(cause, "retry"); 2067 } 2068 } 2069 2070 bool G1CollectedHeap::try_collect(GCCause::Cause cause, 2071 const G1GCCounters& counters_before) { 2072 if (should_do_concurrent_full_gc(cause)) { 2073 return try_collect_concurrently(cause, 2074 counters_before.total_collections(), 2075 counters_before.old_marking_cycles_started()); 2076 } else if (GCLocker::should_discard(cause, counters_before.total_collections())) { 2077 // Indicate failure to be consistent with VMOp failure due to 2078 // another collection slipping in after our gc_count but before 2079 // our request is processed. 2080 return false; 2081 } else if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc 2082 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { 2083 2084 // Schedule a standard evacuation pause. We're setting word_size 2085 // to 0 which means that we are not requesting a post-GC allocation. 2086 VM_G1CollectForAllocation op(0, /* word_size */ 2087 counters_before.total_collections(), 2088 cause); 2089 VMThread::execute(&op); 2090 return op.gc_succeeded(); 2091 } else { 2092 // Schedule a Full GC. 2093 VM_G1CollectFull op(counters_before.total_collections(), 2094 counters_before.total_full_collections(), 2095 cause); 2096 VMThread::execute(&op); 2097 return op.gc_succeeded(); 2098 } 2099 } 2100 2101 void G1CollectedHeap::start_concurrent_gc_for_metadata_allocation(GCCause::Cause gc_cause) { 2102 GCCauseSetter x(this, gc_cause); 2103 2104 // At this point we are supposed to start a concurrent cycle. We 2105 // will do so if one is not already in progress. 2106 bool should_start = policy()->force_concurrent_start_if_outside_cycle(gc_cause); 2107 if (should_start) { 2108 do_collection_pause_at_safepoint(); 2109 } 2110 } 2111 2112 bool G1CollectedHeap::is_in(const void* p) const { 2113 return is_in_reserved(p) && _hrm.is_available(addr_to_region(p)); 2114 } 2115 2116 // Iteration functions. 2117 2118 // Iterates an ObjectClosure over all objects within a HeapRegion. 2119 2120 class IterateObjectClosureRegionClosure: public HeapRegionClosure { 2121 ObjectClosure* _cl; 2122 public: 2123 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} 2124 bool do_heap_region(HeapRegion* r) { 2125 if (!r->is_continues_humongous()) { 2126 r->object_iterate(_cl); 2127 } 2128 return false; 2129 } 2130 }; 2131 2132 void G1CollectedHeap::object_iterate(ObjectClosure* cl) { 2133 IterateObjectClosureRegionClosure blk(cl); 2134 heap_region_iterate(&blk); 2135 } 2136 2137 class G1ParallelObjectIterator : public ParallelObjectIteratorImpl { 2138 private: 2139 G1CollectedHeap* _heap; 2140 HeapRegionClaimer _claimer; 2141 2142 public: 2143 G1ParallelObjectIterator(uint thread_num) : 2144 _heap(G1CollectedHeap::heap()), 2145 _claimer(thread_num == 0 ? G1CollectedHeap::heap()->workers()->active_workers() : thread_num) {} 2146 2147 virtual void object_iterate(ObjectClosure* cl, uint worker_id) { 2148 _heap->object_iterate_parallel(cl, worker_id, &_claimer); 2149 } 2150 }; 2151 2152 ParallelObjectIteratorImpl* G1CollectedHeap::parallel_object_iterator(uint thread_num) { 2153 return new G1ParallelObjectIterator(thread_num); 2154 } 2155 2156 void G1CollectedHeap::object_iterate_parallel(ObjectClosure* cl, uint worker_id, HeapRegionClaimer* claimer) { 2157 IterateObjectClosureRegionClosure blk(cl); 2158 heap_region_par_iterate_from_worker_offset(&blk, claimer, worker_id); 2159 } 2160 2161 void G1CollectedHeap::keep_alive(oop obj) { 2162 G1BarrierSet::enqueue_preloaded(obj); 2163 } 2164 2165 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { 2166 _hrm.iterate(cl); 2167 } 2168 2169 void G1CollectedHeap::heap_region_iterate(HeapRegionIndexClosure* cl) const { 2170 _hrm.iterate(cl); 2171 } 2172 2173 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl, 2174 HeapRegionClaimer *hrclaimer, 2175 uint worker_id) const { 2176 _hrm.par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id)); 2177 } 2178 2179 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl, 2180 HeapRegionClaimer *hrclaimer) const { 2181 _hrm.par_iterate(cl, hrclaimer, 0); 2182 } 2183 2184 void G1CollectedHeap::collection_set_iterate_all(HeapRegionClosure* cl) { 2185 _collection_set.iterate(cl); 2186 } 2187 2188 void G1CollectedHeap::collection_set_par_iterate_all(HeapRegionClosure* cl, 2189 HeapRegionClaimer* hr_claimer, 2190 uint worker_id) { 2191 _collection_set.par_iterate(cl, hr_claimer, worker_id); 2192 } 2193 2194 void G1CollectedHeap::collection_set_iterate_increment_from(HeapRegionClosure *cl, 2195 HeapRegionClaimer* hr_claimer, 2196 uint worker_id) { 2197 _collection_set.iterate_incremental_part_from(cl, hr_claimer, worker_id); 2198 } 2199 2200 void G1CollectedHeap::par_iterate_regions_array(HeapRegionClosure* cl, 2201 HeapRegionClaimer* hr_claimer, 2202 const uint regions[], 2203 size_t length, 2204 uint worker_id) const { 2205 assert_at_safepoint(); 2206 if (length == 0) { 2207 return; 2208 } 2209 uint total_workers = workers()->active_workers(); 2210 2211 size_t start_pos = (worker_id * length) / total_workers; 2212 size_t cur_pos = start_pos; 2213 2214 do { 2215 uint region_idx = regions[cur_pos]; 2216 if (hr_claimer == NULL || hr_claimer->claim_region(region_idx)) { 2217 HeapRegion* r = region_at(region_idx); 2218 bool result = cl->do_heap_region(r); 2219 guarantee(!result, "Must not cancel iteration"); 2220 } 2221 2222 cur_pos++; 2223 if (cur_pos == length) { 2224 cur_pos = 0; 2225 } 2226 } while (cur_pos != start_pos); 2227 } 2228 2229 HeapWord* G1CollectedHeap::block_start(const void* addr) const { 2230 HeapRegion* hr = heap_region_containing(addr); 2231 // The CollectedHeap API requires us to not fail for any given address within 2232 // the heap. HeapRegion::block_start() has been optimized to not accept addresses 2233 // outside of the allocated area. 2234 if (addr >= hr->top()) { 2235 return nullptr; 2236 } 2237 return hr->block_start(addr); 2238 } 2239 2240 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { 2241 HeapRegion* hr = heap_region_containing(addr); 2242 return hr->block_is_obj(addr, hr->parsable_bottom_acquire()); 2243 } 2244 2245 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { 2246 return (_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes; 2247 } 2248 2249 size_t G1CollectedHeap::tlab_used(Thread* ignored) const { 2250 return _eden.length() * HeapRegion::GrainBytes; 2251 } 2252 2253 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size 2254 // must be equal to the humongous object limit. 2255 size_t G1CollectedHeap::max_tlab_size() const { 2256 return align_down(_humongous_object_threshold_in_words, MinObjAlignment); 2257 } 2258 2259 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { 2260 return _allocator->unsafe_max_tlab_alloc(); 2261 } 2262 2263 size_t G1CollectedHeap::max_capacity() const { 2264 return max_regions() * HeapRegion::GrainBytes; 2265 } 2266 2267 void G1CollectedHeap::prepare_for_verify() { 2268 _verifier->prepare_for_verify(); 2269 } 2270 2271 void G1CollectedHeap::verify(VerifyOption vo) { 2272 _verifier->verify(vo); 2273 } 2274 2275 bool G1CollectedHeap::supports_concurrent_gc_breakpoints() const { 2276 return true; 2277 } 2278 2279 bool G1CollectedHeap::is_archived_object(oop object) const { 2280 return object != NULL && heap_region_containing(object)->is_archive(); 2281 } 2282 2283 class PrintRegionClosure: public HeapRegionClosure { 2284 outputStream* _st; 2285 public: 2286 PrintRegionClosure(outputStream* st) : _st(st) {} 2287 bool do_heap_region(HeapRegion* r) { 2288 r->print_on(_st); 2289 return false; 2290 } 2291 }; 2292 2293 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2294 const HeapRegion* hr, 2295 const VerifyOption vo) const { 2296 switch (vo) { 2297 case VerifyOption::G1UseConcMarking: return is_obj_dead(obj, hr); 2298 case VerifyOption::G1UseFullMarking: return is_obj_dead_full(obj, hr); 2299 default: ShouldNotReachHere(); 2300 } 2301 return false; // keep some compilers happy 2302 } 2303 2304 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2305 const VerifyOption vo) const { 2306 switch (vo) { 2307 case VerifyOption::G1UseConcMarking: return is_obj_dead(obj); 2308 case VerifyOption::G1UseFullMarking: return is_obj_dead_full(obj); 2309 default: ShouldNotReachHere(); 2310 } 2311 return false; // keep some compilers happy 2312 } 2313 2314 void G1CollectedHeap::pin_object(JavaThread* thread, oop obj) { 2315 GCLocker::lock_critical(thread); 2316 } 2317 2318 void G1CollectedHeap::unpin_object(JavaThread* thread, oop obj) { 2319 GCLocker::unlock_critical(thread); 2320 } 2321 2322 void G1CollectedHeap::print_heap_regions() const { 2323 LogTarget(Trace, gc, heap, region) lt; 2324 if (lt.is_enabled()) { 2325 LogStream ls(lt); 2326 print_regions_on(&ls); 2327 } 2328 } 2329 2330 void G1CollectedHeap::print_on(outputStream* st) const { 2331 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked(); 2332 st->print(" %-20s", "garbage-first heap"); 2333 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 2334 capacity()/K, heap_used/K); 2335 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")", 2336 p2i(_hrm.reserved().start()), 2337 p2i(_hrm.reserved().end())); 2338 st->cr(); 2339 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); 2340 uint young_regions = young_regions_count(); 2341 st->print("%u young (" SIZE_FORMAT "K), ", young_regions, 2342 (size_t) young_regions * HeapRegion::GrainBytes / K); 2343 uint survivor_regions = survivor_regions_count(); 2344 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, 2345 (size_t) survivor_regions * HeapRegion::GrainBytes / K); 2346 st->cr(); 2347 if (_numa->is_enabled()) { 2348 uint num_nodes = _numa->num_active_nodes(); 2349 st->print(" remaining free region(s) on each NUMA node: "); 2350 const int* node_ids = _numa->node_ids(); 2351 for (uint node_index = 0; node_index < num_nodes; node_index++) { 2352 uint num_free_regions = _hrm.num_free_regions(node_index); 2353 st->print("%d=%u ", node_ids[node_index], num_free_regions); 2354 } 2355 st->cr(); 2356 } 2357 MetaspaceUtils::print_on(st); 2358 } 2359 2360 void G1CollectedHeap::print_regions_on(outputStream* st) const { 2361 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, " 2362 "HS=humongous(starts), HC=humongous(continues), " 2363 "CS=collection set, F=free, " 2364 "OA=open archive, CA=closed archive, " 2365 "TAMS=top-at-mark-start, " 2366 "PB=parsable bottom"); 2367 PrintRegionClosure blk(st); 2368 heap_region_iterate(&blk); 2369 } 2370 2371 void G1CollectedHeap::print_extended_on(outputStream* st) const { 2372 print_on(st); 2373 2374 // Print the per-region information. 2375 st->cr(); 2376 print_regions_on(st); 2377 } 2378 2379 void G1CollectedHeap::print_on_error(outputStream* st) const { 2380 this->CollectedHeap::print_on_error(st); 2381 2382 if (_cm != NULL) { 2383 st->cr(); 2384 _cm->print_on_error(st); 2385 } 2386 } 2387 2388 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { 2389 workers()->threads_do(tc); 2390 tc->do_thread(_cm_thread); 2391 _cm->threads_do(tc); 2392 _cr->threads_do(tc); 2393 tc->do_thread(_service_thread); 2394 } 2395 2396 void G1CollectedHeap::print_tracing_info() const { 2397 rem_set()->print_summary_info(); 2398 concurrent_mark()->print_summary_info(); 2399 } 2400 2401 bool G1CollectedHeap::print_location(outputStream* st, void* addr) const { 2402 return BlockLocationPrinter<G1CollectedHeap>::print_location(st, addr); 2403 } 2404 2405 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() { 2406 2407 size_t eden_used_bytes = _monitoring_support->eden_space_used(); 2408 size_t survivor_used_bytes = _monitoring_support->survivor_space_used(); 2409 size_t old_gen_used_bytes = _monitoring_support->old_gen_used(); 2410 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked(); 2411 2412 size_t eden_capacity_bytes = 2413 (policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes; 2414 2415 VirtualSpaceSummary heap_summary = create_heap_space_summary(); 2416 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes, eden_capacity_bytes, 2417 survivor_used_bytes, old_gen_used_bytes, num_regions()); 2418 } 2419 2420 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) { 2421 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(), 2422 stats->unused(), stats->used(), stats->region_end_waste(), 2423 stats->regions_filled(), stats->num_plab_filled(), 2424 stats->direct_allocated(), stats->num_direct_allocated(), 2425 stats->failure_used(), stats->failure_waste()); 2426 } 2427 2428 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) { 2429 const G1HeapSummary& heap_summary = create_g1_heap_summary(); 2430 gc_tracer->report_gc_heap_summary(when, heap_summary); 2431 2432 const MetaspaceSummary& metaspace_summary = create_metaspace_summary(); 2433 gc_tracer->report_metaspace_summary(when, metaspace_summary); 2434 } 2435 2436 void G1CollectedHeap::gc_prologue(bool full) { 2437 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 2438 2439 // Update common counters. 2440 increment_total_collections(full /* full gc */); 2441 if (full || collector_state()->in_concurrent_start_gc()) { 2442 increment_old_marking_cycles_started(); 2443 } 2444 } 2445 2446 void G1CollectedHeap::gc_epilogue(bool full) { 2447 // Update common counters. 2448 if (full) { 2449 // Update the number of full collections that have been completed. 2450 increment_old_marking_cycles_completed(false /* concurrent */, true /* liveness_completed */); 2451 } 2452 2453 #if COMPILER2_OR_JVMCI 2454 assert(DerivedPointerTable::is_empty(), "derived pointer present"); 2455 #endif 2456 2457 // We have just completed a GC. Update the soft reference 2458 // policy with the new heap occupancy 2459 Universe::heap()->update_capacity_and_used_at_gc(); 2460 2461 _collection_pause_end = Ticks::now(); 2462 2463 _free_arena_memory_task->notify_new_stats(&_young_gen_card_set_stats, 2464 &_collection_set_candidates_card_set_stats); 2465 } 2466 2467 uint G1CollectedHeap::uncommit_regions(uint region_limit) { 2468 return _hrm.uncommit_inactive_regions(region_limit); 2469 } 2470 2471 bool G1CollectedHeap::has_uncommittable_regions() { 2472 return _hrm.has_inactive_regions(); 2473 } 2474 2475 void G1CollectedHeap::uncommit_regions_if_necessary() { 2476 if (has_uncommittable_regions()) { 2477 G1UncommitRegionTask::enqueue(); 2478 } 2479 } 2480 2481 void G1CollectedHeap::verify_numa_regions(const char* desc) { 2482 LogTarget(Trace, gc, heap, verify) lt; 2483 2484 if (lt.is_enabled()) { 2485 LogStream ls(lt); 2486 // Iterate all heap regions to print matching between preferred numa id and actual numa id. 2487 G1NodeIndexCheckClosure cl(desc, _numa, &ls); 2488 heap_region_iterate(&cl); 2489 } 2490 } 2491 2492 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, 2493 uint gc_count_before, 2494 bool* succeeded, 2495 GCCause::Cause gc_cause) { 2496 assert_heap_not_locked_and_not_at_safepoint(); 2497 VM_G1CollectForAllocation op(word_size, gc_count_before, gc_cause); 2498 VMThread::execute(&op); 2499 2500 HeapWord* result = op.result(); 2501 bool ret_succeeded = op.prologue_succeeded() && op.gc_succeeded(); 2502 assert(result == NULL || ret_succeeded, 2503 "the result should be NULL if the VM did not succeed"); 2504 *succeeded = ret_succeeded; 2505 2506 assert_heap_not_locked(); 2507 return result; 2508 } 2509 2510 void G1CollectedHeap::start_concurrent_cycle(bool concurrent_operation_is_full_mark) { 2511 assert(!_cm_thread->in_progress(), "Can not start concurrent operation while in progress"); 2512 2513 MutexLocker x(CGC_lock, Mutex::_no_safepoint_check_flag); 2514 if (concurrent_operation_is_full_mark) { 2515 _cm->post_concurrent_mark_start(); 2516 _cm_thread->start_full_mark(); 2517 } else { 2518 _cm->post_concurrent_undo_start(); 2519 _cm_thread->start_undo_mark(); 2520 } 2521 CGC_lock->notify(); 2522 } 2523 2524 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const { 2525 // We don't nominate objects with many remembered set entries, on 2526 // the assumption that such objects are likely still live. 2527 HeapRegionRemSet* rem_set = r->rem_set(); 2528 2529 return rem_set->occupancy_less_or_equal_than(G1EagerReclaimRemSetThreshold); 2530 } 2531 2532 #ifndef PRODUCT 2533 void G1CollectedHeap::verify_region_attr_remset_is_tracked() { 2534 class VerifyRegionAttrRemSet : public HeapRegionClosure { 2535 public: 2536 virtual bool do_heap_region(HeapRegion* r) { 2537 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 2538 bool const remset_is_tracked = g1h->region_attr(r->bottom()).remset_is_tracked(); 2539 assert(r->rem_set()->is_tracked() == remset_is_tracked, 2540 "Region %u remset tracking status (%s) different to region attribute (%s)", 2541 r->hrm_index(), BOOL_TO_STR(r->rem_set()->is_tracked()), BOOL_TO_STR(remset_is_tracked)); 2542 return false; 2543 } 2544 } cl; 2545 heap_region_iterate(&cl); 2546 } 2547 #endif 2548 2549 void G1CollectedHeap::start_new_collection_set() { 2550 collection_set()->start_incremental_building(); 2551 2552 clear_region_attr(); 2553 2554 guarantee(_eden.length() == 0, "eden should have been cleared"); 2555 policy()->transfer_survivors_to_cset(survivor()); 2556 2557 // We redo the verification but now wrt to the new CSet which 2558 // has just got initialized after the previous CSet was freed. 2559 _cm->verify_no_collection_set_oops(); 2560 } 2561 2562 G1HeapVerifier::G1VerifyType G1CollectedHeap::young_collection_verify_type() const { 2563 if (collector_state()->in_concurrent_start_gc()) { 2564 return G1HeapVerifier::G1VerifyConcurrentStart; 2565 } else if (collector_state()->in_young_only_phase()) { 2566 return G1HeapVerifier::G1VerifyYoungNormal; 2567 } else { 2568 return G1HeapVerifier::G1VerifyMixed; 2569 } 2570 } 2571 2572 void G1CollectedHeap::verify_before_young_collection(G1HeapVerifier::G1VerifyType type) { 2573 if (!VerifyBeforeGC) { 2574 return; 2575 } 2576 Ticks start = Ticks::now(); 2577 _verifier->prepare_for_verify(); 2578 _verifier->verify_region_sets_optional(); 2579 _verifier->verify_dirty_young_regions(); 2580 _verifier->verify_before_gc(type); 2581 verify_numa_regions("GC Start"); 2582 phase_times()->record_verify_before_time_ms((Ticks::now() - start).seconds() * MILLIUNITS); 2583 } 2584 2585 void G1CollectedHeap::verify_after_young_collection(G1HeapVerifier::G1VerifyType type) { 2586 if (!VerifyAfterGC) { 2587 return; 2588 } 2589 Ticks start = Ticks::now(); 2590 _verifier->verify_after_gc(type); 2591 verify_numa_regions("GC End"); 2592 _verifier->verify_region_sets_optional(); 2593 phase_times()->record_verify_after_time_ms((Ticks::now() - start).seconds() * MILLIUNITS); 2594 } 2595 2596 void G1CollectedHeap::expand_heap_after_young_collection(){ 2597 size_t expand_bytes = _heap_sizing_policy->young_collection_expansion_amount(); 2598 if (expand_bytes > 0) { 2599 // No need for an ergo logging here, 2600 // expansion_amount() does this when it returns a value > 0. 2601 double expand_ms = 0.0; 2602 if (!expand(expand_bytes, _workers, &expand_ms)) { 2603 // We failed to expand the heap. Cannot do anything about it. 2604 } 2605 phase_times()->record_expand_heap_time(expand_ms); 2606 } 2607 } 2608 2609 bool G1CollectedHeap::do_collection_pause_at_safepoint() { 2610 assert_at_safepoint_on_vm_thread(); 2611 guarantee(!is_gc_active(), "collection is not reentrant"); 2612 2613 if (GCLocker::check_active_before_gc()) { 2614 return false; 2615 } 2616 2617 do_collection_pause_at_safepoint_helper(); 2618 return true; 2619 } 2620 2621 G1HeapPrinterMark::G1HeapPrinterMark(G1CollectedHeap* g1h) : _g1h(g1h), _heap_transition(g1h) { 2622 // This summary needs to be printed before incrementing total collections. 2623 _g1h->rem_set()->print_periodic_summary_info("Before GC RS summary", 2624 _g1h->total_collections(), 2625 true /* show_thread_times */); 2626 _g1h->print_heap_before_gc(); 2627 _g1h->print_heap_regions(); 2628 } 2629 2630 G1HeapPrinterMark::~G1HeapPrinterMark() { 2631 _g1h->policy()->print_age_table(); 2632 _g1h->rem_set()->print_coarsen_stats(); 2633 // We are at the end of the GC. Total collections has already been increased. 2634 _g1h->rem_set()->print_periodic_summary_info("After GC RS summary", 2635 _g1h->total_collections() - 1, 2636 false /* show_thread_times */); 2637 2638 _heap_transition.print(); 2639 _g1h->print_heap_regions(); 2640 _g1h->print_heap_after_gc(); 2641 // Print NUMA statistics. 2642 _g1h->numa()->print_statistics(); 2643 } 2644 2645 G1JFRTracerMark::G1JFRTracerMark(STWGCTimer* timer, GCTracer* tracer) : 2646 _timer(timer), _tracer(tracer) { 2647 2648 _timer->register_gc_start(); 2649 _tracer->report_gc_start(G1CollectedHeap::heap()->gc_cause(), _timer->gc_start()); 2650 G1CollectedHeap::heap()->trace_heap_before_gc(_tracer); 2651 } 2652 2653 G1JFRTracerMark::~G1JFRTracerMark() { 2654 G1CollectedHeap::heap()->trace_heap_after_gc(_tracer); 2655 _timer->register_gc_end(); 2656 _tracer->report_gc_end(_timer->gc_end(), _timer->time_partitions()); 2657 } 2658 2659 void G1CollectedHeap::prepare_for_mutator_after_young_collection() { 2660 Ticks start = Ticks::now(); 2661 2662 _survivor_evac_stats.adjust_desired_plab_size(); 2663 _old_evac_stats.adjust_desired_plab_size(); 2664 2665 // Start a new incremental collection set for the mutator phase. 2666 start_new_collection_set(); 2667 _allocator->init_mutator_alloc_regions(); 2668 2669 phase_times()->record_prepare_for_mutator_time_ms((Ticks::now() - start).seconds() * 1000.0); 2670 } 2671 2672 void G1CollectedHeap::retire_tlabs() { 2673 ensure_parsability(true); 2674 } 2675 2676 void G1CollectedHeap::do_collection_pause_at_safepoint_helper() { 2677 ResourceMark rm; 2678 2679 IsGCActiveMark active_gc_mark; 2680 GCIdMark gc_id_mark; 2681 SvcGCMarker sgcm(SvcGCMarker::MINOR); 2682 2683 GCTraceCPUTime tcpu(_gc_tracer_stw); 2684 2685 _bytes_used_during_gc = 0; 2686 2687 policy()->decide_on_concurrent_start_pause(); 2688 // Record whether this pause may need to trigger a concurrent operation. Later, 2689 // when we signal the G1ConcurrentMarkThread, the collector state has already 2690 // been reset for the next pause. 2691 bool should_start_concurrent_mark_operation = collector_state()->in_concurrent_start_gc(); 2692 2693 // Perform the collection. 2694 G1YoungCollector collector(gc_cause()); 2695 collector.collect(); 2696 2697 // It should now be safe to tell the concurrent mark thread to start 2698 // without its logging output interfering with the logging output 2699 // that came from the pause. 2700 if (should_start_concurrent_mark_operation) { 2701 verifier()->verify_bitmap_clear(true /* above_tams_only */); 2702 // CAUTION: after the start_concurrent_cycle() call below, the concurrent marking 2703 // thread(s) could be running concurrently with us. Make sure that anything 2704 // after this point does not assume that we are the only GC thread running. 2705 // Note: of course, the actual marking work will not start until the safepoint 2706 // itself is released in SuspendibleThreadSet::desynchronize(). 2707 start_concurrent_cycle(collector.concurrent_operation_is_full_mark()); 2708 ConcurrentGCBreakpoints::notify_idle_to_active(); 2709 } 2710 } 2711 2712 void G1CollectedHeap::complete_cleaning(bool class_unloading_occurred) { 2713 uint num_workers = workers()->active_workers(); 2714 G1ParallelCleaningTask unlink_task(num_workers, class_unloading_occurred); 2715 workers()->run_task(&unlink_task); 2716 } 2717 2718 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) { 2719 assert(obj != NULL, "must not be NULL"); 2720 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj)); 2721 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below 2722 // may falsely indicate that this is not the case here: however the collection set only 2723 // contains old regions when concurrent mark is not running. 2724 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor(); 2725 } 2726 2727 void G1CollectedHeap::make_pending_list_reachable() { 2728 if (collector_state()->in_concurrent_start_gc()) { 2729 oop pll_head = Universe::reference_pending_list(); 2730 if (pll_head != NULL) { 2731 // Any valid worker id is fine here as we are in the VM thread and single-threaded. 2732 _cm->mark_in_bitmap(0 /* worker_id */, pll_head); 2733 } 2734 } 2735 } 2736 2737 void G1CollectedHeap::set_humongous_stats(uint num_humongous_total, uint num_humongous_candidates) { 2738 _num_humongous_objects = num_humongous_total; 2739 _num_humongous_reclaim_candidates = num_humongous_candidates; 2740 } 2741 2742 bool G1CollectedHeap::should_sample_collection_set_candidates() const { 2743 G1CollectionSetCandidates* candidates = G1CollectedHeap::heap()->collection_set()->candidates(); 2744 return candidates != NULL && candidates->num_remaining() > 0; 2745 } 2746 2747 void G1CollectedHeap::set_collection_set_candidates_stats(G1MonotonicArenaMemoryStats& stats) { 2748 _collection_set_candidates_card_set_stats = stats; 2749 } 2750 2751 void G1CollectedHeap::set_young_gen_card_set_stats(const G1MonotonicArenaMemoryStats& stats) { 2752 _young_gen_card_set_stats = stats; 2753 } 2754 2755 void G1CollectedHeap::record_obj_copy_mem_stats() { 2756 policy()->old_gen_alloc_tracker()-> 2757 add_allocated_bytes_since_last_gc(_old_evac_stats.allocated() * HeapWordSize); 2758 2759 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats), 2760 create_g1_evac_summary(&_old_evac_stats)); 2761 } 2762 2763 void G1CollectedHeap::clear_bitmap_for_region(HeapRegion* hr) { 2764 concurrent_mark()->clear_bitmap_for_region(hr); 2765 } 2766 2767 void G1CollectedHeap::free_region(HeapRegion* hr, FreeRegionList* free_list) { 2768 assert(!hr->is_free(), "the region should not be free"); 2769 assert(!hr->is_empty(), "the region should not be empty"); 2770 assert(_hrm.is_available(hr->hrm_index()), "region should be committed"); 2771 2772 // Reset region metadata to allow reuse. 2773 hr->hr_clear(true /* clear_space */); 2774 _policy->remset_tracker()->update_at_free(hr); 2775 2776 if (free_list != NULL) { 2777 free_list->add_ordered(hr); 2778 } 2779 } 2780 2781 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 2782 FreeRegionList* free_list) { 2783 assert(hr->is_humongous(), "this is only for humongous regions"); 2784 hr->clear_humongous(); 2785 free_region(hr, free_list); 2786 } 2787 2788 void G1CollectedHeap::remove_from_old_gen_sets(const uint old_regions_removed, 2789 const uint archive_regions_removed, 2790 const uint humongous_regions_removed) { 2791 if (old_regions_removed > 0 || archive_regions_removed > 0 || humongous_regions_removed > 0) { 2792 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag); 2793 _old_set.bulk_remove(old_regions_removed); 2794 _archive_set.bulk_remove(archive_regions_removed); 2795 _humongous_set.bulk_remove(humongous_regions_removed); 2796 } 2797 2798 } 2799 2800 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) { 2801 assert(list != NULL, "list can't be null"); 2802 if (!list->is_empty()) { 2803 MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag); 2804 _hrm.insert_list_into_free_list(list); 2805 } 2806 } 2807 2808 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) { 2809 decrease_used(bytes); 2810 } 2811 2812 void G1CollectedHeap::clear_eden() { 2813 _eden.clear(); 2814 } 2815 2816 void G1CollectedHeap::clear_collection_set() { 2817 collection_set()->clear(); 2818 } 2819 2820 void G1CollectedHeap::rebuild_free_region_list() { 2821 Ticks start = Ticks::now(); 2822 _hrm.rebuild_free_list(workers()); 2823 phase_times()->record_total_rebuild_freelist_time_ms((Ticks::now() - start).seconds() * 1000.0); 2824 } 2825 2826 class G1AbandonCollectionSetClosure : public HeapRegionClosure { 2827 public: 2828 virtual bool do_heap_region(HeapRegion* r) { 2829 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index()); 2830 G1CollectedHeap::heap()->clear_region_attr(r); 2831 r->clear_young_index_in_cset(); 2832 return false; 2833 } 2834 }; 2835 2836 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) { 2837 G1AbandonCollectionSetClosure cl; 2838 collection_set_iterate_all(&cl); 2839 2840 collection_set->clear(); 2841 collection_set->stop_incremental_building(); 2842 } 2843 2844 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) { 2845 return _allocator->is_retained_old_region(hr); 2846 } 2847 2848 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 2849 _eden.add(hr); 2850 _policy->set_region_eden(hr); 2851 } 2852 2853 #ifdef ASSERT 2854 2855 class NoYoungRegionsClosure: public HeapRegionClosure { 2856 private: 2857 bool _success; 2858 public: 2859 NoYoungRegionsClosure() : _success(true) { } 2860 bool do_heap_region(HeapRegion* r) { 2861 if (r->is_young()) { 2862 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young", 2863 p2i(r->bottom()), p2i(r->end())); 2864 _success = false; 2865 } 2866 return false; 2867 } 2868 bool success() { return _success; } 2869 }; 2870 2871 bool G1CollectedHeap::check_young_list_empty() { 2872 bool ret = (young_regions_count() == 0); 2873 2874 NoYoungRegionsClosure closure; 2875 heap_region_iterate(&closure); 2876 ret = ret && closure.success(); 2877 2878 return ret; 2879 } 2880 2881 #endif // ASSERT 2882 2883 // Remove the given HeapRegion from the appropriate region set. 2884 void G1CollectedHeap::prepare_region_for_full_compaction(HeapRegion* hr) { 2885 if (hr->is_archive()) { 2886 _archive_set.remove(hr); 2887 } else if (hr->is_humongous()) { 2888 _humongous_set.remove(hr); 2889 } else if (hr->is_old()) { 2890 _old_set.remove(hr); 2891 } else if (hr->is_young()) { 2892 // Note that emptying the eden and survivor lists is postponed and instead 2893 // done as the first step when rebuilding the regions sets again. The reason 2894 // for this is that during a full GC string deduplication needs to know if 2895 // a collected region was young or old when the full GC was initiated. 2896 hr->uninstall_surv_rate_group(); 2897 } else { 2898 // We ignore free regions, we'll empty the free list afterwards. 2899 assert(hr->is_free(), "it cannot be another type"); 2900 } 2901 } 2902 2903 void G1CollectedHeap::increase_used(size_t bytes) { 2904 _summary_bytes_used += bytes; 2905 } 2906 2907 void G1CollectedHeap::decrease_used(size_t bytes) { 2908 assert(_summary_bytes_used >= bytes, 2909 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT, 2910 _summary_bytes_used, bytes); 2911 _summary_bytes_used -= bytes; 2912 } 2913 2914 void G1CollectedHeap::set_used(size_t bytes) { 2915 _summary_bytes_used = bytes; 2916 } 2917 2918 class RebuildRegionSetsClosure : public HeapRegionClosure { 2919 private: 2920 bool _free_list_only; 2921 2922 HeapRegionSet* _old_set; 2923 HeapRegionSet* _archive_set; 2924 HeapRegionSet* _humongous_set; 2925 2926 HeapRegionManager* _hrm; 2927 2928 size_t _total_used; 2929 2930 public: 2931 RebuildRegionSetsClosure(bool free_list_only, 2932 HeapRegionSet* old_set, 2933 HeapRegionSet* archive_set, 2934 HeapRegionSet* humongous_set, 2935 HeapRegionManager* hrm) : 2936 _free_list_only(free_list_only), _old_set(old_set), _archive_set(archive_set), 2937 _humongous_set(humongous_set), _hrm(hrm), _total_used(0) { 2938 assert(_hrm->num_free_regions() == 0, "pre-condition"); 2939 if (!free_list_only) { 2940 assert(_old_set->is_empty(), "pre-condition"); 2941 assert(_archive_set->is_empty(), "pre-condition"); 2942 assert(_humongous_set->is_empty(), "pre-condition"); 2943 } 2944 } 2945 2946 bool do_heap_region(HeapRegion* r) { 2947 if (r->is_empty()) { 2948 assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets."); 2949 // Add free regions to the free list 2950 r->set_free(); 2951 _hrm->insert_into_free_list(r); 2952 } else if (!_free_list_only) { 2953 assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared."); 2954 2955 if (r->is_humongous()) { 2956 _humongous_set->add(r); 2957 } else if (r->is_archive()) { 2958 _archive_set->add(r); 2959 } else { 2960 assert(r->is_young() || r->is_free() || r->is_old(), "invariant"); 2961 // We now move all (non-humongous, non-old, non-archive) regions to old gen, 2962 // and register them as such. 2963 r->move_to_old(); 2964 _old_set->add(r); 2965 } 2966 _total_used += r->used(); 2967 } 2968 2969 return false; 2970 } 2971 2972 size_t total_used() { 2973 return _total_used; 2974 } 2975 }; 2976 2977 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { 2978 assert_at_safepoint_on_vm_thread(); 2979 2980 if (!free_list_only) { 2981 _eden.clear(); 2982 _survivor.clear(); 2983 } 2984 2985 RebuildRegionSetsClosure cl(free_list_only, 2986 &_old_set, &_archive_set, &_humongous_set, 2987 &_hrm); 2988 heap_region_iterate(&cl); 2989 2990 if (!free_list_only) { 2991 set_used(cl.total_used()); 2992 } 2993 assert_used_and_recalculate_used_equal(this); 2994 } 2995 2996 // Methods for the mutator alloc region 2997 2998 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 2999 bool force, 3000 uint node_index) { 3001 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 3002 bool should_allocate = policy()->should_allocate_mutator_region(); 3003 if (force || should_allocate) { 3004 HeapRegion* new_alloc_region = new_region(word_size, 3005 HeapRegionType::Eden, 3006 false /* do_expand */, 3007 node_index); 3008 if (new_alloc_region != NULL) { 3009 set_region_short_lived_locked(new_alloc_region); 3010 _hr_printer.alloc(new_alloc_region, !should_allocate); 3011 _policy->remset_tracker()->update_at_allocate(new_alloc_region); 3012 return new_alloc_region; 3013 } 3014 } 3015 return NULL; 3016 } 3017 3018 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 3019 size_t allocated_bytes) { 3020 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 3021 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden"); 3022 3023 collection_set()->add_eden_region(alloc_region); 3024 increase_used(allocated_bytes); 3025 _eden.add_used_bytes(allocated_bytes); 3026 _hr_printer.retire(alloc_region); 3027 3028 // We update the eden sizes here, when the region is retired, 3029 // instead of when it's allocated, since this is the point that its 3030 // used space has been recorded in _summary_bytes_used. 3031 monitoring_support()->update_eden_size(); 3032 } 3033 3034 // Methods for the GC alloc regions 3035 3036 bool G1CollectedHeap::has_more_regions(G1HeapRegionAttr dest) { 3037 if (dest.is_old()) { 3038 return true; 3039 } else { 3040 return survivor_regions_count() < policy()->max_survivor_regions(); 3041 } 3042 } 3043 3044 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest, uint node_index) { 3045 assert(FreeList_lock->owned_by_self(), "pre-condition"); 3046 3047 if (!has_more_regions(dest)) { 3048 return NULL; 3049 } 3050 3051 HeapRegionType type; 3052 if (dest.is_young()) { 3053 type = HeapRegionType::Survivor; 3054 } else { 3055 type = HeapRegionType::Old; 3056 } 3057 3058 HeapRegion* new_alloc_region = new_region(word_size, 3059 type, 3060 true /* do_expand */, 3061 node_index); 3062 3063 if (new_alloc_region != NULL) { 3064 if (type.is_survivor()) { 3065 new_alloc_region->set_survivor(); 3066 _survivor.add(new_alloc_region); 3067 register_new_survivor_region_with_region_attr(new_alloc_region); 3068 } else { 3069 new_alloc_region->set_old(); 3070 } 3071 _policy->remset_tracker()->update_at_allocate(new_alloc_region); 3072 register_region_with_region_attr(new_alloc_region); 3073 _hr_printer.alloc(new_alloc_region); 3074 return new_alloc_region; 3075 } 3076 return NULL; 3077 } 3078 3079 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 3080 size_t allocated_bytes, 3081 G1HeapRegionAttr dest) { 3082 _bytes_used_during_gc += allocated_bytes; 3083 if (dest.is_old()) { 3084 old_set_add(alloc_region); 3085 } else { 3086 assert(dest.is_young(), "Retiring alloc region should be young (%d)", dest.type()); 3087 _survivor.add_used_bytes(allocated_bytes); 3088 } 3089 3090 bool const during_im = collector_state()->in_concurrent_start_gc(); 3091 if (during_im && allocated_bytes > 0) { 3092 _cm->add_root_region(alloc_region); 3093 } 3094 _hr_printer.retire(alloc_region); 3095 } 3096 3097 HeapRegion* G1CollectedHeap::alloc_highest_free_region() { 3098 bool expanded = false; 3099 uint index = _hrm.find_highest_free(&expanded); 3100 3101 if (index != G1_NO_HRM_INDEX) { 3102 if (expanded) { 3103 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B", 3104 HeapRegion::GrainWords * HeapWordSize); 3105 } 3106 return _hrm.allocate_free_regions_starting_at(index, 1); 3107 } 3108 return NULL; 3109 } 3110 3111 void G1CollectedHeap::mark_evac_failure_object(uint worker_id, const oop obj, size_t obj_size) const { 3112 assert(!_cm->is_marked_in_bitmap(obj), "must be"); 3113 3114 _cm->raw_mark_in_bitmap(obj); 3115 if (collector_state()->in_concurrent_start_gc()) { 3116 _cm->add_to_liveness(worker_id, obj, obj_size); 3117 } 3118 } 3119 3120 // Optimized nmethod scanning 3121 class RegisterNMethodOopClosure: public OopClosure { 3122 G1CollectedHeap* _g1h; 3123 nmethod* _nm; 3124 3125 public: 3126 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 3127 _g1h(g1h), _nm(nm) {} 3128 3129 void do_oop(oop* p) { 3130 oop heap_oop = RawAccess<>::oop_load(p); 3131 if (!CompressedOops::is_null(heap_oop)) { 3132 oop obj = CompressedOops::decode_not_null(heap_oop); 3133 HeapRegion* hr = _g1h->heap_region_containing(obj); 3134 assert(!hr->is_continues_humongous(), 3135 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 3136 " starting at " HR_FORMAT, 3137 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 3138 3139 // HeapRegion::add_code_root_locked() avoids adding duplicate entries. 3140 hr->add_code_root_locked(_nm); 3141 } 3142 } 3143 3144 void do_oop(narrowOop* p) { ShouldNotReachHere(); } 3145 }; 3146 3147 class UnregisterNMethodOopClosure: public OopClosure { 3148 G1CollectedHeap* _g1h; 3149 nmethod* _nm; 3150 3151 public: 3152 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 3153 _g1h(g1h), _nm(nm) {} 3154 3155 void do_oop(oop* p) { 3156 oop heap_oop = RawAccess<>::oop_load(p); 3157 if (!CompressedOops::is_null(heap_oop)) { 3158 oop obj = CompressedOops::decode_not_null(heap_oop); 3159 HeapRegion* hr = _g1h->heap_region_containing(obj); 3160 assert(!hr->is_continues_humongous(), 3161 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 3162 " starting at " HR_FORMAT, 3163 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 3164 3165 hr->remove_code_root(_nm); 3166 } 3167 } 3168 3169 void do_oop(narrowOop* p) { ShouldNotReachHere(); } 3170 }; 3171 3172 void G1CollectedHeap::register_nmethod(nmethod* nm) { 3173 guarantee(nm != NULL, "sanity"); 3174 RegisterNMethodOopClosure reg_cl(this, nm); 3175 nm->oops_do(®_cl); 3176 } 3177 3178 void G1CollectedHeap::unregister_nmethod(nmethod* nm) { 3179 guarantee(nm != NULL, "sanity"); 3180 UnregisterNMethodOopClosure reg_cl(this, nm); 3181 nm->oops_do(®_cl, true); 3182 } 3183 3184 void G1CollectedHeap::update_used_after_gc(bool evacuation_failed) { 3185 if (evacuation_failed) { 3186 // Reset the G1EvacuationFailureALot counters and flags 3187 evac_failure_injector()->reset(); 3188 3189 set_used(recalculate_used()); 3190 } else { 3191 // The "used" of the collection set have already been subtracted 3192 // when they were freed. Add in the bytes used. 3193 increase_used(_bytes_used_during_gc); 3194 } 3195 } 3196 3197 class RebuildCodeRootClosure: public CodeBlobClosure { 3198 G1CollectedHeap* _g1h; 3199 3200 public: 3201 RebuildCodeRootClosure(G1CollectedHeap* g1h) : 3202 _g1h(g1h) {} 3203 3204 void do_code_blob(CodeBlob* cb) { 3205 nmethod* nm = cb->as_nmethod_or_null(); 3206 if (nm != NULL) { 3207 _g1h->register_nmethod(nm); 3208 } 3209 } 3210 }; 3211 3212 void G1CollectedHeap::rebuild_code_roots() { 3213 RebuildCodeRootClosure blob_cl(this); 3214 CodeCache::blobs_do(&blob_cl); 3215 } 3216 3217 void G1CollectedHeap::initialize_serviceability() { 3218 _monitoring_support->initialize_serviceability(); 3219 } 3220 3221 MemoryUsage G1CollectedHeap::memory_usage() { 3222 return _monitoring_support->memory_usage(); 3223 } 3224 3225 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() { 3226 return _monitoring_support->memory_managers(); 3227 } 3228 3229 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() { 3230 return _monitoring_support->memory_pools(); 3231 } 3232 3233 void G1CollectedHeap::fill_with_dummy_object(HeapWord* start, HeapWord* end, bool zap) { 3234 HeapRegion* region = heap_region_containing(start); 3235 region->fill_with_dummy_object(start, pointer_delta(end, start), zap); 3236 } 3237 3238 void G1CollectedHeap::start_codecache_marking_cycle_if_inactive(bool concurrent_mark_start) { 3239 // We can reach here with an active code cache marking cycle either because the 3240 // previous G1 concurrent marking cycle was undone (if heap occupancy after the 3241 // concurrent start young collection was below the threshold) or aborted. See 3242 // CodeCache::on_gc_marking_cycle_finish() why this is. We must not start a new code 3243 // cache cycle then. If we are about to start a new g1 concurrent marking cycle we 3244 // still have to arm all nmethod entry barriers. They are needed for adding oop 3245 // constants to the SATB snapshot. Full GC does not need nmethods to be armed. 3246 if (!CodeCache::is_gc_marking_cycle_active()) { 3247 CodeCache::on_gc_marking_cycle_start(); 3248 } 3249 if (concurrent_mark_start) { 3250 CodeCache::arm_all_nmethods(); 3251 } 3252 } 3253 3254 void G1CollectedHeap::finish_codecache_marking_cycle() { 3255 CodeCache::on_gc_marking_cycle_finish(); 3256 CodeCache::arm_all_nmethods(); 3257 }