1 /* 2 * Copyright (c) 2001, 2018, 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/metadataOnStackMark.hpp" 27 #include "classfile/stringTable.hpp" 28 #include "code/codeCache.hpp" 29 #include "code/icBuffer.hpp" 30 #include "gc/g1/g1Allocator.inline.hpp" 31 #include "gc/g1/g1BarrierSet.hpp" 32 #include "gc/g1/g1CollectedHeap.inline.hpp" 33 #include "gc/g1/g1CollectionSet.hpp" 34 #include "gc/g1/g1CollectorPolicy.hpp" 35 #include "gc/g1/g1CollectorState.hpp" 36 #include "gc/g1/g1ConcurrentRefine.hpp" 37 #include "gc/g1/g1ConcurrentRefineThread.hpp" 38 #include "gc/g1/g1ConcurrentMarkThread.inline.hpp" 39 #include "gc/g1/g1EvacStats.inline.hpp" 40 #include "gc/g1/g1FullCollector.hpp" 41 #include "gc/g1/g1GCPhaseTimes.hpp" 42 #include "gc/g1/g1HeapSizingPolicy.hpp" 43 #include "gc/g1/g1HeapTransition.hpp" 44 #include "gc/g1/g1HeapVerifier.hpp" 45 #include "gc/g1/g1HotCardCache.hpp" 46 #include "gc/g1/g1MemoryPool.hpp" 47 #include "gc/g1/g1OopClosures.inline.hpp" 48 #include "gc/g1/g1ParScanThreadState.inline.hpp" 49 #include "gc/g1/g1Policy.hpp" 50 #include "gc/g1/g1RegionToSpaceMapper.hpp" 51 #include "gc/g1/g1RemSet.hpp" 52 #include "gc/g1/g1RootClosures.hpp" 53 #include "gc/g1/g1RootProcessor.hpp" 54 #include "gc/g1/g1SATBMarkQueueSet.hpp" 55 #include "gc/g1/g1StringDedup.hpp" 56 #include "gc/g1/g1ThreadLocalData.hpp" 57 #include "gc/g1/g1YCTypes.hpp" 58 #include "gc/g1/g1YoungRemSetSamplingThread.hpp" 59 #include "gc/g1/heapRegion.inline.hpp" 60 #include "gc/g1/heapRegionRemSet.hpp" 61 #include "gc/g1/heapRegionSet.inline.hpp" 62 #include "gc/g1/vm_operations_g1.hpp" 63 #include "gc/shared/adaptiveSizePolicy.hpp" 64 #include "gc/shared/gcHeapSummary.hpp" 65 #include "gc/shared/gcId.hpp" 66 #include "gc/shared/gcLocker.hpp" 67 #include "gc/shared/gcTimer.hpp" 68 #include "gc/shared/gcTrace.hpp" 69 #include "gc/shared/gcTraceTime.inline.hpp" 70 #include "gc/shared/generationSpec.hpp" 71 #include "gc/shared/isGCActiveMark.hpp" 72 #include "gc/shared/oopStorageParState.hpp" 73 #include "gc/shared/preservedMarks.inline.hpp" 74 #include "gc/shared/suspendibleThreadSet.hpp" 75 #include "gc/shared/referenceProcessor.inline.hpp" 76 #include "gc/shared/taskqueue.inline.hpp" 77 #include "gc/shared/weakProcessor.hpp" 78 #include "logging/log.hpp" 79 #include "memory/allocation.hpp" 80 #include "memory/iterator.hpp" 81 #include "memory/metaspaceShared.hpp" 82 #include "memory/resourceArea.hpp" 83 #include "oops/access.inline.hpp" 84 #include "oops/compressedOops.inline.hpp" 85 #include "oops/oop.inline.hpp" 86 #include "prims/resolvedMethodTable.hpp" 87 #include "runtime/atomic.hpp" 88 #include "runtime/flags/flagSetting.hpp" 89 #include "runtime/handles.inline.hpp" 90 #include "runtime/init.hpp" 91 #include "runtime/orderAccess.hpp" 92 #include "runtime/threadSMR.hpp" 93 #include "runtime/vmThread.hpp" 94 #include "utilities/align.hpp" 95 #include "utilities/globalDefinitions.hpp" 96 #include "utilities/stack.inline.hpp" 97 98 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0; 99 100 // INVARIANTS/NOTES 101 // 102 // All allocation activity covered by the G1CollectedHeap interface is 103 // serialized by acquiring the HeapLock. This happens in mem_allocate 104 // and allocate_new_tlab, which are the "entry" points to the 105 // allocation code from the rest of the JVM. (Note that this does not 106 // apply to TLAB allocation, which is not part of this interface: it 107 // is done by clients of this interface.) 108 109 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure { 110 private: 111 size_t _num_dirtied; 112 G1CollectedHeap* _g1h; 113 G1CardTable* _g1_ct; 114 115 HeapRegion* region_for_card(jbyte* card_ptr) const { 116 return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr)); 117 } 118 119 bool will_become_free(HeapRegion* hr) const { 120 // A region will be freed by free_collection_set if the region is in the 121 // collection set and has not had an evacuation failure. 122 return _g1h->is_in_cset(hr) && !hr->evacuation_failed(); 123 } 124 125 public: 126 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(), 127 _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { } 128 129 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 130 HeapRegion* hr = region_for_card(card_ptr); 131 132 // Should only dirty cards in regions that won't be freed. 133 if (!will_become_free(hr)) { 134 *card_ptr = G1CardTable::dirty_card_val(); 135 _num_dirtied++; 136 } 137 138 return true; 139 } 140 141 size_t num_dirtied() const { return _num_dirtied; } 142 }; 143 144 145 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) { 146 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions); 147 } 148 149 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) { 150 // The from card cache is not the memory that is actually committed. So we cannot 151 // take advantage of the zero_filled parameter. 152 reset_from_card_cache(start_idx, num_regions); 153 } 154 155 156 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index, 157 MemRegion mr) { 158 return new HeapRegion(hrs_index, bot(), mr); 159 } 160 161 // Private methods. 162 163 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) { 164 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords, 165 "the only time we use this to allocate a humongous region is " 166 "when we are allocating a single humongous region"); 167 168 HeapRegion* res = _hrm.allocate_free_region(is_old); 169 170 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) { 171 // Currently, only attempts to allocate GC alloc regions set 172 // do_expand to true. So, we should only reach here during a 173 // safepoint. If this assumption changes we might have to 174 // reconsider the use of _expand_heap_after_alloc_failure. 175 assert(SafepointSynchronize::is_at_safepoint(), "invariant"); 176 177 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B", 178 word_size * HeapWordSize); 179 180 if (expand(word_size * HeapWordSize)) { 181 // Given that expand() succeeded in expanding the heap, and we 182 // always expand the heap by an amount aligned to the heap 183 // region size, the free list should in theory not be empty. 184 // In either case allocate_free_region() will check for NULL. 185 res = _hrm.allocate_free_region(is_old); 186 } else { 187 _expand_heap_after_alloc_failure = false; 188 } 189 } 190 return res; 191 } 192 193 HeapWord* 194 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first, 195 uint num_regions, 196 size_t word_size) { 197 assert(first != G1_NO_HRM_INDEX, "pre-condition"); 198 assert(is_humongous(word_size), "word_size should be humongous"); 199 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition"); 200 201 // Index of last region in the series. 202 uint last = first + num_regions - 1; 203 204 // We need to initialize the region(s) we just discovered. This is 205 // a bit tricky given that it can happen concurrently with 206 // refinement threads refining cards on these regions and 207 // potentially wanting to refine the BOT as they are scanning 208 // those cards (this can happen shortly after a cleanup; see CR 209 // 6991377). So we have to set up the region(s) carefully and in 210 // a specific order. 211 212 // The word size sum of all the regions we will allocate. 213 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords; 214 assert(word_size <= word_size_sum, "sanity"); 215 216 // This will be the "starts humongous" region. 217 HeapRegion* first_hr = region_at(first); 218 // The header of the new object will be placed at the bottom of 219 // the first region. 220 HeapWord* new_obj = first_hr->bottom(); 221 // This will be the new top of the new object. 222 HeapWord* obj_top = new_obj + word_size; 223 224 // First, we need to zero the header of the space that we will be 225 // allocating. When we update top further down, some refinement 226 // threads might try to scan the region. By zeroing the header we 227 // ensure that any thread that will try to scan the region will 228 // come across the zero klass word and bail out. 229 // 230 // NOTE: It would not have been correct to have used 231 // CollectedHeap::fill_with_object() and make the space look like 232 // an int array. The thread that is doing the allocation will 233 // later update the object header to a potentially different array 234 // type and, for a very short period of time, the klass and length 235 // fields will be inconsistent. This could cause a refinement 236 // thread to calculate the object size incorrectly. 237 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0); 238 239 // Next, pad out the unused tail of the last region with filler 240 // objects, for improved usage accounting. 241 // How many words we use for filler objects. 242 size_t word_fill_size = word_size_sum - word_size; 243 244 // How many words memory we "waste" which cannot hold a filler object. 245 size_t words_not_fillable = 0; 246 247 if (word_fill_size >= min_fill_size()) { 248 fill_with_objects(obj_top, word_fill_size); 249 } else if (word_fill_size > 0) { 250 // We have space to fill, but we cannot fit an object there. 251 words_not_fillable = word_fill_size; 252 word_fill_size = 0; 253 } 254 255 // We will set up the first region as "starts humongous". This 256 // will also update the BOT covering all the regions to reflect 257 // that there is a single object that starts at the bottom of the 258 // first region. 259 first_hr->set_starts_humongous(obj_top, word_fill_size); 260 _g1_policy->remset_tracker()->update_at_allocate(first_hr); 261 // Then, if there are any, we will set up the "continues 262 // humongous" regions. 263 HeapRegion* hr = NULL; 264 for (uint i = first + 1; i <= last; ++i) { 265 hr = region_at(i); 266 hr->set_continues_humongous(first_hr); 267 _g1_policy->remset_tracker()->update_at_allocate(hr); 268 } 269 270 // Up to this point no concurrent thread would have been able to 271 // do any scanning on any region in this series. All the top 272 // fields still point to bottom, so the intersection between 273 // [bottom,top] and [card_start,card_end] will be empty. Before we 274 // update the top fields, we'll do a storestore to make sure that 275 // no thread sees the update to top before the zeroing of the 276 // object header and the BOT initialization. 277 OrderAccess::storestore(); 278 279 // Now, we will update the top fields of the "continues humongous" 280 // regions except the last one. 281 for (uint i = first; i < last; ++i) { 282 hr = region_at(i); 283 hr->set_top(hr->end()); 284 } 285 286 hr = region_at(last); 287 // If we cannot fit a filler object, we must set top to the end 288 // of the humongous object, otherwise we cannot iterate the heap 289 // and the BOT will not be complete. 290 hr->set_top(hr->end() - words_not_fillable); 291 292 assert(hr->bottom() < obj_top && obj_top <= hr->end(), 293 "obj_top should be in last region"); 294 295 _verifier->check_bitmaps("Humongous Region Allocation", first_hr); 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 first = G1_NO_HRM_INDEX; 326 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size); 327 328 if (obj_regions == 1) { 329 // Only one region to allocate, try to use a fast path by directly allocating 330 // from the free lists. Do not try to expand here, we will potentially do that 331 // later. 332 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */); 333 if (hr != NULL) { 334 first = hr->hrm_index(); 335 } 336 } else { 337 // Policy: Try only empty regions (i.e. already committed first). Maybe we 338 // are lucky enough to find some. 339 first = _hrm.find_contiguous_only_empty(obj_regions); 340 if (first != G1_NO_HRM_INDEX) { 341 _hrm.allocate_free_regions_starting_at(first, obj_regions); 342 } 343 } 344 345 if (first == G1_NO_HRM_INDEX) { 346 // Policy: We could not find enough regions for the humongous object in the 347 // free list. Look through the heap to find a mix of free and uncommitted regions. 348 // If so, try expansion. 349 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions); 350 if (first != G1_NO_HRM_INDEX) { 351 // We found something. Make sure these regions are committed, i.e. expand 352 // the heap. Alternatively we could do a defragmentation GC. 353 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B", 354 word_size * HeapWordSize); 355 356 _hrm.expand_at(first, obj_regions, workers()); 357 g1_policy()->record_new_heap_size(num_regions()); 358 359 #ifdef ASSERT 360 for (uint i = first; i < first + obj_regions; ++i) { 361 HeapRegion* hr = region_at(i); 362 assert(hr->is_free(), "sanity"); 363 assert(hr->is_empty(), "sanity"); 364 assert(is_on_master_free_list(hr), "sanity"); 365 } 366 #endif 367 _hrm.allocate_free_regions_starting_at(first, obj_regions); 368 } else { 369 // Policy: Potentially trigger a defragmentation GC. 370 } 371 } 372 373 HeapWord* result = NULL; 374 if (first != G1_NO_HRM_INDEX) { 375 result = humongous_obj_allocate_initialize_regions(first, obj_regions, word_size); 376 assert(result != NULL, "it should always return a valid result"); 377 378 // A successful humongous object allocation changes the used space 379 // information of the old generation so we need to recalculate the 380 // sizes and update the jstat counters here. 381 g1mm()->update_sizes(); 382 } 383 384 _verifier->verify_region_sets_optional(); 385 386 return result; 387 } 388 389 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size, 390 size_t requested_size, 391 size_t* actual_size) { 392 assert_heap_not_locked_and_not_at_safepoint(); 393 assert(!is_humongous(requested_size), "we do not allow humongous TLABs"); 394 395 return attempt_allocation(min_size, requested_size, actual_size); 396 } 397 398 HeapWord* 399 G1CollectedHeap::mem_allocate(size_t word_size, 400 bool* gc_overhead_limit_was_exceeded) { 401 assert_heap_not_locked_and_not_at_safepoint(); 402 403 if (is_humongous(word_size)) { 404 return attempt_allocation_humongous(word_size); 405 } 406 size_t dummy = 0; 407 return attempt_allocation(word_size, word_size, &dummy); 408 } 409 410 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) { 411 ResourceMark rm; // For retrieving the thread names in log messages. 412 413 // Make sure you read the note in attempt_allocation_humongous(). 414 415 assert_heap_not_locked_and_not_at_safepoint(); 416 assert(!is_humongous(word_size), "attempt_allocation_slow() should not " 417 "be called for humongous allocation requests"); 418 419 // We should only get here after the first-level allocation attempt 420 // (attempt_allocation()) failed to allocate. 421 422 // We will loop until a) we manage to successfully perform the 423 // allocation or b) we successfully schedule a collection which 424 // fails to perform the allocation. b) is the only case when we'll 425 // return NULL. 426 HeapWord* result = NULL; 427 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 428 bool should_try_gc; 429 uint gc_count_before; 430 431 { 432 MutexLockerEx x(Heap_lock); 433 result = _allocator->attempt_allocation_locked(word_size); 434 if (result != NULL) { 435 return result; 436 } 437 438 // If the GCLocker is active and we are bound for a GC, try expanding young gen. 439 // This is different to when only GCLocker::needs_gc() is set: try to avoid 440 // waiting because the GCLocker is active to not wait too long. 441 if (GCLocker::is_active_and_needs_gc() && g1_policy()->can_expand_young_list()) { 442 // No need for an ergo message here, can_expand_young_list() does this when 443 // it returns true. 444 result = _allocator->attempt_allocation_force(word_size); 445 if (result != NULL) { 446 return result; 447 } 448 } 449 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until 450 // the GCLocker initiated GC has been performed and then retry. This includes 451 // the case when the GC Locker is not active but has not been performed. 452 should_try_gc = !GCLocker::needs_gc(); 453 // Read the GC count while still holding the Heap_lock. 454 gc_count_before = total_collections(); 455 } 456 457 if (should_try_gc) { 458 bool succeeded; 459 result = do_collection_pause(word_size, gc_count_before, &succeeded, 460 GCCause::_g1_inc_collection_pause); 461 if (result != NULL) { 462 assert(succeeded, "only way to get back a non-NULL result"); 463 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT, 464 Thread::current()->name(), p2i(result)); 465 return result; 466 } 467 468 if (succeeded) { 469 // We successfully scheduled a collection which failed to allocate. No 470 // point in trying to allocate further. We'll just return NULL. 471 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate " 472 SIZE_FORMAT " words", Thread::current()->name(), word_size); 473 return NULL; 474 } 475 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words", 476 Thread::current()->name(), word_size); 477 } else { 478 // Failed to schedule a collection. 479 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 480 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating " 481 SIZE_FORMAT " words", Thread::current()->name(), word_size); 482 return NULL; 483 } 484 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name()); 485 // The GCLocker is either active or the GCLocker initiated 486 // GC has not yet been performed. Stall until it is and 487 // then retry the allocation. 488 GCLocker::stall_until_clear(); 489 gclocker_retry_count += 1; 490 } 491 492 // We can reach here if we were unsuccessful in scheduling a 493 // collection (because another thread beat us to it) or if we were 494 // stalled due to the GC locker. In either can we should retry the 495 // allocation attempt in case another thread successfully 496 // performed a collection and reclaimed enough space. We do the 497 // first attempt (without holding the Heap_lock) here and the 498 // follow-on attempt will be at the start of the next loop 499 // iteration (after taking the Heap_lock). 500 size_t dummy = 0; 501 result = _allocator->attempt_allocation(word_size, word_size, &dummy); 502 if (result != NULL) { 503 return result; 504 } 505 506 // Give a warning if we seem to be looping forever. 507 if ((QueuedAllocationWarningCount > 0) && 508 (try_count % QueuedAllocationWarningCount == 0)) { 509 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words", 510 Thread::current()->name(), try_count, word_size); 511 } 512 } 513 514 ShouldNotReachHere(); 515 return NULL; 516 } 517 518 void G1CollectedHeap::begin_archive_alloc_range(bool open) { 519 assert_at_safepoint_on_vm_thread(); 520 if (_archive_allocator == NULL) { 521 _archive_allocator = G1ArchiveAllocator::create_allocator(this, open); 522 } 523 } 524 525 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) { 526 // Allocations in archive regions cannot be of a size that would be considered 527 // humongous even for a minimum-sized region, because G1 region sizes/boundaries 528 // may be different at archive-restore time. 529 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words()); 530 } 531 532 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) { 533 assert_at_safepoint_on_vm_thread(); 534 assert(_archive_allocator != NULL, "_archive_allocator not initialized"); 535 if (is_archive_alloc_too_large(word_size)) { 536 return NULL; 537 } 538 return _archive_allocator->archive_mem_allocate(word_size); 539 } 540 541 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges, 542 size_t end_alignment_in_bytes) { 543 assert_at_safepoint_on_vm_thread(); 544 assert(_archive_allocator != NULL, "_archive_allocator not initialized"); 545 546 // Call complete_archive to do the real work, filling in the MemRegion 547 // array with the archive regions. 548 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes); 549 delete _archive_allocator; 550 _archive_allocator = NULL; 551 } 552 553 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) { 554 assert(ranges != NULL, "MemRegion array NULL"); 555 assert(count != 0, "No MemRegions provided"); 556 MemRegion reserved = _hrm.reserved(); 557 for (size_t i = 0; i < count; i++) { 558 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) { 559 return false; 560 } 561 } 562 return true; 563 } 564 565 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, 566 size_t count, 567 bool open) { 568 assert(!is_init_completed(), "Expect to be called at JVM init time"); 569 assert(ranges != NULL, "MemRegion array NULL"); 570 assert(count != 0, "No MemRegions provided"); 571 MutexLockerEx x(Heap_lock); 572 573 MemRegion reserved = _hrm.reserved(); 574 HeapWord* prev_last_addr = NULL; 575 HeapRegion* prev_last_region = NULL; 576 577 // Temporarily disable pretouching of heap pages. This interface is used 578 // when mmap'ing archived heap data in, so pre-touching is wasted. 579 FlagSetting fs(AlwaysPreTouch, false); 580 581 // Enable archive object checking used by G1MarkSweep. We have to let it know 582 // about each archive range, so that objects in those ranges aren't marked. 583 G1ArchiveAllocator::enable_archive_object_check(); 584 585 // For each specified MemRegion range, allocate the corresponding G1 586 // regions and mark them as archive regions. We expect the ranges 587 // in ascending starting address order, without overlap. 588 for (size_t i = 0; i < count; i++) { 589 MemRegion curr_range = ranges[i]; 590 HeapWord* start_address = curr_range.start(); 591 size_t word_size = curr_range.word_size(); 592 HeapWord* last_address = curr_range.last(); 593 size_t commits = 0; 594 595 guarantee(reserved.contains(start_address) && reserved.contains(last_address), 596 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 597 p2i(start_address), p2i(last_address)); 598 guarantee(start_address > prev_last_addr, 599 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 600 p2i(start_address), p2i(prev_last_addr)); 601 prev_last_addr = last_address; 602 603 // Check for ranges that start in the same G1 region in which the previous 604 // range ended, and adjust the start address so we don't try to allocate 605 // the same region again. If the current range is entirely within that 606 // region, skip it, just adjusting the recorded top. 607 HeapRegion* start_region = _hrm.addr_to_region(start_address); 608 if ((prev_last_region != NULL) && (start_region == prev_last_region)) { 609 start_address = start_region->end(); 610 if (start_address > last_address) { 611 increase_used(word_size * HeapWordSize); 612 start_region->set_top(last_address + 1); 613 continue; 614 } 615 start_region->set_top(start_address); 616 curr_range = MemRegion(start_address, last_address + 1); 617 start_region = _hrm.addr_to_region(start_address); 618 } 619 620 // Perform the actual region allocation, exiting if it fails. 621 // Then note how much new space we have allocated. 622 if (!_hrm.allocate_containing_regions(curr_range, &commits, workers())) { 623 return false; 624 } 625 increase_used(word_size * HeapWordSize); 626 if (commits != 0) { 627 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B", 628 HeapRegion::GrainWords * HeapWordSize * commits); 629 630 } 631 632 // Mark each G1 region touched by the range as archive, add it to 633 // the old set, and set top. 634 HeapRegion* curr_region = _hrm.addr_to_region(start_address); 635 HeapRegion* last_region = _hrm.addr_to_region(last_address); 636 prev_last_region = last_region; 637 638 while (curr_region != NULL) { 639 assert(curr_region->is_empty() && !curr_region->is_pinned(), 640 "Region already in use (index %u)", curr_region->hrm_index()); 641 if (open) { 642 curr_region->set_open_archive(); 643 } else { 644 curr_region->set_closed_archive(); 645 } 646 _hr_printer.alloc(curr_region); 647 _old_set.add(curr_region); 648 HeapWord* top; 649 HeapRegion* next_region; 650 if (curr_region != last_region) { 651 top = curr_region->end(); 652 next_region = _hrm.next_region_in_heap(curr_region); 653 } else { 654 top = last_address + 1; 655 next_region = NULL; 656 } 657 curr_region->set_top(top); 658 curr_region->set_first_dead(top); 659 curr_region->set_end_of_live(top); 660 curr_region = next_region; 661 } 662 663 // Notify mark-sweep of the archive 664 G1ArchiveAllocator::set_range_archive(curr_range, open); 665 } 666 return true; 667 } 668 669 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) { 670 assert(!is_init_completed(), "Expect to be called at JVM init time"); 671 assert(ranges != NULL, "MemRegion array NULL"); 672 assert(count != 0, "No MemRegions provided"); 673 MemRegion reserved = _hrm.reserved(); 674 HeapWord *prev_last_addr = NULL; 675 HeapRegion* prev_last_region = NULL; 676 677 // For each MemRegion, create filler objects, if needed, in the G1 regions 678 // that contain the address range. The address range actually within the 679 // MemRegion will not be modified. That is assumed to have been initialized 680 // elsewhere, probably via an mmap of archived heap data. 681 MutexLockerEx x(Heap_lock); 682 for (size_t i = 0; i < count; i++) { 683 HeapWord* start_address = ranges[i].start(); 684 HeapWord* last_address = ranges[i].last(); 685 686 assert(reserved.contains(start_address) && reserved.contains(last_address), 687 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 688 p2i(start_address), p2i(last_address)); 689 assert(start_address > prev_last_addr, 690 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 691 p2i(start_address), p2i(prev_last_addr)); 692 693 HeapRegion* start_region = _hrm.addr_to_region(start_address); 694 HeapRegion* last_region = _hrm.addr_to_region(last_address); 695 HeapWord* bottom_address = start_region->bottom(); 696 697 // Check for a range beginning in the same region in which the 698 // previous one ended. 699 if (start_region == prev_last_region) { 700 bottom_address = prev_last_addr + 1; 701 } 702 703 // Verify that the regions were all marked as archive regions by 704 // alloc_archive_regions. 705 HeapRegion* curr_region = start_region; 706 while (curr_region != NULL) { 707 guarantee(curr_region->is_archive(), 708 "Expected archive region at index %u", curr_region->hrm_index()); 709 if (curr_region != last_region) { 710 curr_region = _hrm.next_region_in_heap(curr_region); 711 } else { 712 curr_region = NULL; 713 } 714 } 715 716 prev_last_addr = last_address; 717 prev_last_region = last_region; 718 719 // Fill the memory below the allocated range with dummy object(s), 720 // if the region bottom does not match the range start, or if the previous 721 // range ended within the same G1 region, and there is a gap. 722 if (start_address != bottom_address) { 723 size_t fill_size = pointer_delta(start_address, bottom_address); 724 G1CollectedHeap::fill_with_objects(bottom_address, fill_size); 725 increase_used(fill_size * HeapWordSize); 726 } 727 } 728 } 729 730 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size, 731 size_t desired_word_size, 732 size_t* actual_word_size) { 733 assert_heap_not_locked_and_not_at_safepoint(); 734 assert(!is_humongous(desired_word_size), "attempt_allocation() should not " 735 "be called for humongous allocation requests"); 736 737 HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size); 738 739 if (result == NULL) { 740 *actual_word_size = desired_word_size; 741 result = attempt_allocation_slow(desired_word_size); 742 } 743 744 assert_heap_not_locked(); 745 if (result != NULL) { 746 assert(*actual_word_size != 0, "Actual size must have been set here"); 747 dirty_young_block(result, *actual_word_size); 748 } else { 749 *actual_word_size = 0; 750 } 751 752 return result; 753 } 754 755 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) { 756 assert(!is_init_completed(), "Expect to be called at JVM init time"); 757 assert(ranges != NULL, "MemRegion array NULL"); 758 assert(count != 0, "No MemRegions provided"); 759 MemRegion reserved = _hrm.reserved(); 760 HeapWord* prev_last_addr = NULL; 761 HeapRegion* prev_last_region = NULL; 762 size_t size_used = 0; 763 size_t uncommitted_regions = 0; 764 765 // For each Memregion, free the G1 regions that constitute it, and 766 // notify mark-sweep that the range is no longer to be considered 'archive.' 767 MutexLockerEx x(Heap_lock); 768 for (size_t i = 0; i < count; i++) { 769 HeapWord* start_address = ranges[i].start(); 770 HeapWord* last_address = ranges[i].last(); 771 772 assert(reserved.contains(start_address) && reserved.contains(last_address), 773 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 774 p2i(start_address), p2i(last_address)); 775 assert(start_address > prev_last_addr, 776 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 777 p2i(start_address), p2i(prev_last_addr)); 778 size_used += ranges[i].byte_size(); 779 prev_last_addr = last_address; 780 781 HeapRegion* start_region = _hrm.addr_to_region(start_address); 782 HeapRegion* last_region = _hrm.addr_to_region(last_address); 783 784 // Check for ranges that start in the same G1 region in which the previous 785 // range ended, and adjust the start address so we don't try to free 786 // the same region again. If the current range is entirely within that 787 // region, skip it. 788 if (start_region == prev_last_region) { 789 start_address = start_region->end(); 790 if (start_address > last_address) { 791 continue; 792 } 793 start_region = _hrm.addr_to_region(start_address); 794 } 795 prev_last_region = last_region; 796 797 // After verifying that each region was marked as an archive region by 798 // alloc_archive_regions, set it free and empty and uncommit it. 799 HeapRegion* curr_region = start_region; 800 while (curr_region != NULL) { 801 guarantee(curr_region->is_archive(), 802 "Expected archive region at index %u", curr_region->hrm_index()); 803 uint curr_index = curr_region->hrm_index(); 804 _old_set.remove(curr_region); 805 curr_region->set_free(); 806 curr_region->set_top(curr_region->bottom()); 807 if (curr_region != last_region) { 808 curr_region = _hrm.next_region_in_heap(curr_region); 809 } else { 810 curr_region = NULL; 811 } 812 _hrm.shrink_at(curr_index, 1); 813 uncommitted_regions++; 814 } 815 816 // Notify mark-sweep that this is no longer an archive range. 817 G1ArchiveAllocator::set_range_archive(ranges[i], false); 818 } 819 820 if (uncommitted_regions != 0) { 821 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B", 822 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions); 823 } 824 decrease_used(size_used); 825 } 826 827 oop G1CollectedHeap::materialize_archived_object(oop obj) { 828 assert(obj != NULL, "archived obj is NULL"); 829 assert(MetaspaceShared::is_archive_object(obj), "must be archived object"); 830 831 // Loading an archived object makes it strongly reachable. If it is 832 // loaded during concurrent marking, it must be enqueued to the SATB 833 // queue, shading the previously white object gray. 834 G1BarrierSet::enqueue(obj); 835 836 return obj; 837 } 838 839 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) { 840 ResourceMark rm; // For retrieving the thread names in log messages. 841 842 // The structure of this method has a lot of similarities to 843 // attempt_allocation_slow(). The reason these two were not merged 844 // into a single one is that such a method would require several "if 845 // allocation is not humongous do this, otherwise do that" 846 // conditional paths which would obscure its flow. In fact, an early 847 // version of this code did use a unified method which was harder to 848 // follow and, as a result, it had subtle bugs that were hard to 849 // track down. So keeping these two methods separate allows each to 850 // be more readable. It will be good to keep these two in sync as 851 // much as possible. 852 853 assert_heap_not_locked_and_not_at_safepoint(); 854 assert(is_humongous(word_size), "attempt_allocation_humongous() " 855 "should only be called for humongous allocations"); 856 857 // Humongous objects can exhaust the heap quickly, so we should check if we 858 // need to start a marking cycle at each humongous object allocation. We do 859 // the check before we do the actual allocation. The reason for doing it 860 // before the allocation is that we avoid having to keep track of the newly 861 // allocated memory while we do a GC. 862 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation", 863 word_size)) { 864 collect(GCCause::_g1_humongous_allocation); 865 } 866 867 // We will loop until a) we manage to successfully perform the 868 // allocation or b) we successfully schedule a collection which 869 // fails to perform the allocation. b) is the only case when we'll 870 // return NULL. 871 HeapWord* result = NULL; 872 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 873 bool should_try_gc; 874 uint gc_count_before; 875 876 877 { 878 MutexLockerEx x(Heap_lock); 879 880 // Given that humongous objects are not allocated in young 881 // regions, we'll first try to do the allocation without doing a 882 // collection hoping that there's enough space in the heap. 883 result = humongous_obj_allocate(word_size); 884 if (result != NULL) { 885 size_t size_in_regions = humongous_obj_size_in_regions(word_size); 886 g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes); 887 return result; 888 } 889 890 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until 891 // the GCLocker initiated GC has been performed and then retry. This includes 892 // the case when the GC Locker is not active but has not been performed. 893 should_try_gc = !GCLocker::needs_gc(); 894 // Read the GC count while still holding the Heap_lock. 895 gc_count_before = total_collections(); 896 } 897 898 if (should_try_gc) { 899 bool succeeded; 900 result = do_collection_pause(word_size, gc_count_before, &succeeded, 901 GCCause::_g1_humongous_allocation); 902 if (result != NULL) { 903 assert(succeeded, "only way to get back a non-NULL result"); 904 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT, 905 Thread::current()->name(), p2i(result)); 906 return result; 907 } 908 909 if (succeeded) { 910 // We successfully scheduled a collection which failed to allocate. No 911 // point in trying to allocate further. We'll just return NULL. 912 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate " 913 SIZE_FORMAT " words", Thread::current()->name(), word_size); 914 return NULL; 915 } 916 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "", 917 Thread::current()->name(), word_size); 918 } else { 919 // Failed to schedule a collection. 920 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 921 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating " 922 SIZE_FORMAT " words", Thread::current()->name(), word_size); 923 return NULL; 924 } 925 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name()); 926 // The GCLocker is either active or the GCLocker initiated 927 // GC has not yet been performed. Stall until it is and 928 // then retry the allocation. 929 GCLocker::stall_until_clear(); 930 gclocker_retry_count += 1; 931 } 932 933 934 // We can reach here if we were unsuccessful in scheduling a 935 // collection (because another thread beat us to it) or if we were 936 // stalled due to the GC locker. In either can we should retry the 937 // allocation attempt in case another thread successfully 938 // performed a collection and reclaimed enough space. 939 // Humongous object allocation always needs a lock, so we wait for the retry 940 // in the next iteration of the loop, unlike for the regular iteration case. 941 // Give a warning if we seem to be looping forever. 942 943 if ((QueuedAllocationWarningCount > 0) && 944 (try_count % QueuedAllocationWarningCount == 0)) { 945 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words", 946 Thread::current()->name(), try_count, word_size); 947 } 948 } 949 950 ShouldNotReachHere(); 951 return NULL; 952 } 953 954 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size, 955 bool expect_null_mutator_alloc_region) { 956 assert_at_safepoint_on_vm_thread(); 957 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region, 958 "the current alloc region was unexpectedly found to be non-NULL"); 959 960 if (!is_humongous(word_size)) { 961 return _allocator->attempt_allocation_locked(word_size); 962 } else { 963 HeapWord* result = humongous_obj_allocate(word_size); 964 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) { 965 collector_state()->set_initiate_conc_mark_if_possible(true); 966 } 967 return result; 968 } 969 970 ShouldNotReachHere(); 971 } 972 973 class PostCompactionPrinterClosure: public HeapRegionClosure { 974 private: 975 G1HRPrinter* _hr_printer; 976 public: 977 bool do_heap_region(HeapRegion* hr) { 978 assert(!hr->is_young(), "not expecting to find young regions"); 979 _hr_printer->post_compaction(hr); 980 return false; 981 } 982 983 PostCompactionPrinterClosure(G1HRPrinter* hr_printer) 984 : _hr_printer(hr_printer) { } 985 }; 986 987 void G1CollectedHeap::print_hrm_post_compaction() { 988 if (_hr_printer.is_active()) { 989 PostCompactionPrinterClosure cl(hr_printer()); 990 heap_region_iterate(&cl); 991 } 992 } 993 994 void G1CollectedHeap::abort_concurrent_cycle() { 995 // If we start the compaction before the CM threads finish 996 // scanning the root regions we might trip them over as we'll 997 // be moving objects / updating references. So let's wait until 998 // they are done. By telling them to abort, they should complete 999 // early. 1000 _cm->root_regions()->abort(); 1001 _cm->root_regions()->wait_until_scan_finished(); 1002 1003 // Disable discovery and empty the discovered lists 1004 // for the CM ref processor. 1005 _ref_processor_cm->disable_discovery(); 1006 _ref_processor_cm->abandon_partial_discovery(); 1007 _ref_processor_cm->verify_no_references_recorded(); 1008 1009 // Abandon current iterations of concurrent marking and concurrent 1010 // refinement, if any are in progress. 1011 concurrent_mark()->concurrent_cycle_abort(); 1012 } 1013 1014 void G1CollectedHeap::prepare_heap_for_full_collection() { 1015 // Make sure we'll choose a new allocation region afterwards. 1016 _allocator->release_mutator_alloc_region(); 1017 _allocator->abandon_gc_alloc_regions(); 1018 g1_rem_set()->cleanupHRRS(); 1019 1020 // We may have added regions to the current incremental collection 1021 // set between the last GC or pause and now. We need to clear the 1022 // incremental collection set and then start rebuilding it afresh 1023 // after this full GC. 1024 abandon_collection_set(collection_set()); 1025 1026 tear_down_region_sets(false /* free_list_only */); 1027 } 1028 1029 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) { 1030 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant"); 1031 assert(used() == recalculate_used(), "Should be equal"); 1032 _verifier->verify_region_sets_optional(); 1033 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull); 1034 _verifier->check_bitmaps("Full GC Start"); 1035 } 1036 1037 void G1CollectedHeap::prepare_heap_for_mutators() { 1038 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 1039 ClassLoaderDataGraph::purge(); 1040 MetaspaceUtils::verify_metrics(); 1041 1042 // Prepare heap for normal collections. 1043 assert(num_free_regions() == 0, "we should not have added any free regions"); 1044 rebuild_region_sets(false /* free_list_only */); 1045 abort_refinement(); 1046 resize_if_necessary_after_full_collection(); 1047 1048 // Rebuild the strong code root lists for each region 1049 rebuild_strong_code_roots(); 1050 1051 // Start a new incremental collection set for the next pause 1052 start_new_collection_set(); 1053 1054 _allocator->init_mutator_alloc_region(); 1055 1056 // Post collection state updates. 1057 MetaspaceGC::compute_new_size(); 1058 } 1059 1060 void G1CollectedHeap::abort_refinement() { 1061 if (_hot_card_cache->use_cache()) { 1062 _hot_card_cache->reset_hot_cache(); 1063 } 1064 1065 // Discard all remembered set updates. 1066 G1BarrierSet::dirty_card_queue_set().abandon_logs(); 1067 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty"); 1068 } 1069 1070 void G1CollectedHeap::verify_after_full_collection() { 1071 _hrm.verify_optional(); 1072 _verifier->verify_region_sets_optional(); 1073 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull); 1074 // Clear the previous marking bitmap, if needed for bitmap verification. 1075 // Note we cannot do this when we clear the next marking bitmap in 1076 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the 1077 // objects marked during a full GC against the previous bitmap. 1078 // But we need to clear it before calling check_bitmaps below since 1079 // the full GC has compacted objects and updated TAMS but not updated 1080 // the prev bitmap. 1081 if (G1VerifyBitmaps) { 1082 GCTraceTime(Debug, gc)("Clear Bitmap for Verification"); 1083 _cm->clear_prev_bitmap(workers()); 1084 } 1085 _verifier->check_bitmaps("Full GC End"); 1086 1087 // At this point there should be no regions in the 1088 // entire heap tagged as young. 1089 assert(check_young_list_empty(), "young list should be empty at this point"); 1090 1091 // Note: since we've just done a full GC, concurrent 1092 // marking is no longer active. Therefore we need not 1093 // re-enable reference discovery for the CM ref processor. 1094 // That will be done at the start of the next marking cycle. 1095 // We also know that the STW processor should no longer 1096 // discover any new references. 1097 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition"); 1098 assert(!_ref_processor_cm->discovery_enabled(), "Postcondition"); 1099 _ref_processor_stw->verify_no_references_recorded(); 1100 _ref_processor_cm->verify_no_references_recorded(); 1101 } 1102 1103 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) { 1104 // Post collection logging. 1105 // We should do this after we potentially resize the heap so 1106 // that all the COMMIT / UNCOMMIT events are generated before 1107 // the compaction events. 1108 print_hrm_post_compaction(); 1109 heap_transition->print(); 1110 print_heap_after_gc(); 1111 print_heap_regions(); 1112 #ifdef TRACESPINNING 1113 ParallelTaskTerminator::print_termination_counts(); 1114 #endif 1115 } 1116 1117 bool G1CollectedHeap::do_full_collection(bool explicit_gc, 1118 bool clear_all_soft_refs) { 1119 assert_at_safepoint_on_vm_thread(); 1120 1121 if (GCLocker::check_active_before_gc()) { 1122 // Full GC was not completed. 1123 return false; 1124 } 1125 1126 const bool do_clear_all_soft_refs = clear_all_soft_refs || 1127 soft_ref_policy()->should_clear_all_soft_refs(); 1128 1129 G1FullCollector collector(this, &_full_gc_memory_manager, explicit_gc, do_clear_all_soft_refs); 1130 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true); 1131 1132 collector.prepare_collection(); 1133 collector.collect(); 1134 collector.complete_collection(); 1135 1136 // Full collection was successfully completed. 1137 return true; 1138 } 1139 1140 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) { 1141 // Currently, there is no facility in the do_full_collection(bool) API to notify 1142 // the caller that the collection did not succeed (e.g., because it was locked 1143 // out by the GC locker). So, right now, we'll ignore the return value. 1144 bool dummy = do_full_collection(true, /* explicit_gc */ 1145 clear_all_soft_refs); 1146 } 1147 1148 void G1CollectedHeap::resize_if_necessary_after_full_collection() { 1149 // Capacity, free and used after the GC counted as full regions to 1150 // include the waste in the following calculations. 1151 const size_t capacity_after_gc = capacity(); 1152 const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes(); 1153 1154 // This is enforced in arguments.cpp. 1155 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, 1156 "otherwise the code below doesn't make sense"); 1157 1158 // We don't have floating point command-line arguments 1159 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0; 1160 const double maximum_used_percentage = 1.0 - minimum_free_percentage; 1161 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0; 1162 const double minimum_used_percentage = 1.0 - maximum_free_percentage; 1163 1164 const size_t min_heap_size = collector_policy()->min_heap_byte_size(); 1165 const size_t max_heap_size = collector_policy()->max_heap_byte_size(); 1166 1167 // We have to be careful here as these two calculations can overflow 1168 // 32-bit size_t's. 1169 double used_after_gc_d = (double) used_after_gc; 1170 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage; 1171 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage; 1172 1173 // Let's make sure that they are both under the max heap size, which 1174 // by default will make them fit into a size_t. 1175 double desired_capacity_upper_bound = (double) max_heap_size; 1176 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d, 1177 desired_capacity_upper_bound); 1178 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d, 1179 desired_capacity_upper_bound); 1180 1181 // We can now safely turn them into size_t's. 1182 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d; 1183 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d; 1184 1185 // This assert only makes sense here, before we adjust them 1186 // with respect to the min and max heap size. 1187 assert(minimum_desired_capacity <= maximum_desired_capacity, 1188 "minimum_desired_capacity = " SIZE_FORMAT ", " 1189 "maximum_desired_capacity = " SIZE_FORMAT, 1190 minimum_desired_capacity, maximum_desired_capacity); 1191 1192 // Should not be greater than the heap max size. No need to adjust 1193 // it with respect to the heap min size as it's a lower bound (i.e., 1194 // we'll try to make the capacity larger than it, not smaller). 1195 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size); 1196 // Should not be less than the heap min size. No need to adjust it 1197 // with respect to the heap max size as it's an upper bound (i.e., 1198 // we'll try to make the capacity smaller than it, not greater). 1199 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size); 1200 1201 if (capacity_after_gc < minimum_desired_capacity) { 1202 // Don't expand unless it's significant 1203 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc; 1204 1205 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). " 1206 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B " 1207 "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)", 1208 capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio); 1209 1210 expand(expand_bytes, _workers); 1211 1212 // No expansion, now see if we want to shrink 1213 } else if (capacity_after_gc > maximum_desired_capacity) { 1214 // Capacity too large, compute shrinking size 1215 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity; 1216 1217 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). " 1218 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B " 1219 "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)", 1220 capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio); 1221 1222 shrink(shrink_bytes); 1223 } 1224 } 1225 1226 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size, 1227 bool do_gc, 1228 bool clear_all_soft_refs, 1229 bool expect_null_mutator_alloc_region, 1230 bool* gc_succeeded) { 1231 *gc_succeeded = true; 1232 // Let's attempt the allocation first. 1233 HeapWord* result = 1234 attempt_allocation_at_safepoint(word_size, 1235 expect_null_mutator_alloc_region); 1236 if (result != NULL) { 1237 return result; 1238 } 1239 1240 // In a G1 heap, we're supposed to keep allocation from failing by 1241 // incremental pauses. Therefore, at least for now, we'll favor 1242 // expansion over collection. (This might change in the future if we can 1243 // do something smarter than full collection to satisfy a failed alloc.) 1244 result = expand_and_allocate(word_size); 1245 if (result != NULL) { 1246 return result; 1247 } 1248 1249 if (do_gc) { 1250 // Expansion didn't work, we'll try to do a Full GC. 1251 *gc_succeeded = do_full_collection(false, /* explicit_gc */ 1252 clear_all_soft_refs); 1253 } 1254 1255 return NULL; 1256 } 1257 1258 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size, 1259 bool* succeeded) { 1260 assert_at_safepoint_on_vm_thread(); 1261 1262 // Attempts to allocate followed by Full GC. 1263 HeapWord* result = 1264 satisfy_failed_allocation_helper(word_size, 1265 true, /* do_gc */ 1266 false, /* clear_all_soft_refs */ 1267 false, /* expect_null_mutator_alloc_region */ 1268 succeeded); 1269 1270 if (result != NULL || !*succeeded) { 1271 return result; 1272 } 1273 1274 // Attempts to allocate followed by Full GC that will collect all soft references. 1275 result = satisfy_failed_allocation_helper(word_size, 1276 true, /* do_gc */ 1277 true, /* clear_all_soft_refs */ 1278 true, /* expect_null_mutator_alloc_region */ 1279 succeeded); 1280 1281 if (result != NULL || !*succeeded) { 1282 return result; 1283 } 1284 1285 // Attempts to allocate, no GC 1286 result = satisfy_failed_allocation_helper(word_size, 1287 false, /* do_gc */ 1288 false, /* clear_all_soft_refs */ 1289 true, /* expect_null_mutator_alloc_region */ 1290 succeeded); 1291 1292 if (result != NULL) { 1293 return result; 1294 } 1295 1296 assert(!soft_ref_policy()->should_clear_all_soft_refs(), 1297 "Flag should have been handled and cleared prior to this point"); 1298 1299 // What else? We might try synchronous finalization later. If the total 1300 // space available is large enough for the allocation, then a more 1301 // complete compaction phase than we've tried so far might be 1302 // appropriate. 1303 return NULL; 1304 } 1305 1306 // Attempting to expand the heap sufficiently 1307 // to support an allocation of the given "word_size". If 1308 // successful, perform the allocation and return the address of the 1309 // allocated block, or else "NULL". 1310 1311 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) { 1312 assert_at_safepoint_on_vm_thread(); 1313 1314 _verifier->verify_region_sets_optional(); 1315 1316 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes); 1317 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B", 1318 word_size * HeapWordSize); 1319 1320 1321 if (expand(expand_bytes, _workers)) { 1322 _hrm.verify_optional(); 1323 _verifier->verify_region_sets_optional(); 1324 return attempt_allocation_at_safepoint(word_size, 1325 false /* expect_null_mutator_alloc_region */); 1326 } 1327 return NULL; 1328 } 1329 1330 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) { 1331 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); 1332 aligned_expand_bytes = align_up(aligned_expand_bytes, 1333 HeapRegion::GrainBytes); 1334 1335 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B", 1336 expand_bytes, aligned_expand_bytes); 1337 1338 if (is_maximal_no_gc()) { 1339 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)"); 1340 return false; 1341 } 1342 1343 double expand_heap_start_time_sec = os::elapsedTime(); 1344 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes); 1345 assert(regions_to_expand > 0, "Must expand by at least one region"); 1346 1347 uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers); 1348 if (expand_time_ms != NULL) { 1349 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS; 1350 } 1351 1352 if (expanded_by > 0) { 1353 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes; 1354 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition"); 1355 g1_policy()->record_new_heap_size(num_regions()); 1356 } else { 1357 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)"); 1358 1359 // The expansion of the virtual storage space was unsuccessful. 1360 // Let's see if it was because we ran out of swap. 1361 if (G1ExitOnExpansionFailure && 1362 _hrm.available() >= regions_to_expand) { 1363 // We had head room... 1364 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion"); 1365 } 1366 } 1367 return regions_to_expand > 0; 1368 } 1369 1370 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) { 1371 size_t aligned_shrink_bytes = 1372 ReservedSpace::page_align_size_down(shrink_bytes); 1373 aligned_shrink_bytes = align_down(aligned_shrink_bytes, 1374 HeapRegion::GrainBytes); 1375 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes); 1376 1377 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove); 1378 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes; 1379 1380 1381 log_debug(gc, ergo, heap)("Shrink the heap. requested shrinking amount: " SIZE_FORMAT "B aligned shrinking amount: " SIZE_FORMAT "B attempted shrinking amount: " SIZE_FORMAT "B", 1382 shrink_bytes, aligned_shrink_bytes, shrunk_bytes); 1383 if (num_regions_removed > 0) { 1384 g1_policy()->record_new_heap_size(num_regions()); 1385 } else { 1386 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)"); 1387 } 1388 } 1389 1390 void G1CollectedHeap::shrink(size_t shrink_bytes) { 1391 _verifier->verify_region_sets_optional(); 1392 1393 // We should only reach here at the end of a Full GC which means we 1394 // should not not be holding to any GC alloc regions. The method 1395 // below will make sure of that and do any remaining clean up. 1396 _allocator->abandon_gc_alloc_regions(); 1397 1398 // Instead of tearing down / rebuilding the free lists here, we 1399 // could instead use the remove_all_pending() method on free_list to 1400 // remove only the ones that we need to remove. 1401 tear_down_region_sets(true /* free_list_only */); 1402 shrink_helper(shrink_bytes); 1403 rebuild_region_sets(true /* free_list_only */); 1404 1405 _hrm.verify_optional(); 1406 _verifier->verify_region_sets_optional(); 1407 } 1408 1409 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) : 1410 CollectedHeap(), 1411 _young_gen_sampling_thread(NULL), 1412 _workers(NULL), 1413 _collector_policy(collector_policy), 1414 _card_table(NULL), 1415 _soft_ref_policy(), 1416 _memory_manager("G1 Young Generation", "end of minor GC"), 1417 _full_gc_memory_manager("G1 Old Generation", "end of major GC"), 1418 _eden_pool(NULL), 1419 _survivor_pool(NULL), 1420 _old_pool(NULL), 1421 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()), 1422 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()), 1423 _bot(NULL), 1424 _listener(), 1425 _hrm(), 1426 _allocator(NULL), 1427 _verifier(NULL), 1428 _summary_bytes_used(0), 1429 _archive_allocator(NULL), 1430 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight), 1431 _old_evac_stats("Old", OldPLABSize, PLABWeight), 1432 _expand_heap_after_alloc_failure(true), 1433 _g1mm(NULL), 1434 _humongous_reclaim_candidates(), 1435 _has_humongous_reclaim_candidates(false), 1436 _hr_printer(), 1437 _collector_state(), 1438 _old_marking_cycles_started(0), 1439 _old_marking_cycles_completed(0), 1440 _eden(), 1441 _survivor(), 1442 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()), 1443 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()), 1444 _g1_policy(new G1Policy(_gc_timer_stw)), 1445 _heap_sizing_policy(NULL), 1446 _collection_set(this, _g1_policy), 1447 _hot_card_cache(NULL), 1448 _g1_rem_set(NULL), 1449 _dirty_card_queue_set(false), 1450 _cm(NULL), 1451 _cm_thread(NULL), 1452 _cr(NULL), 1453 _task_queues(NULL), 1454 _evacuation_failed(false), 1455 _evacuation_failed_info_array(NULL), 1456 _preserved_marks_set(true /* in_c_heap */), 1457 #ifndef PRODUCT 1458 _evacuation_failure_alot_for_current_gc(false), 1459 _evacuation_failure_alot_gc_number(0), 1460 _evacuation_failure_alot_count(0), 1461 #endif 1462 _ref_processor_stw(NULL), 1463 _is_alive_closure_stw(this), 1464 _is_subject_to_discovery_stw(this), 1465 _ref_processor_cm(NULL), 1466 _is_alive_closure_cm(this), 1467 _is_subject_to_discovery_cm(this), 1468 _in_cset_fast_test() { 1469 1470 _workers = new WorkGang("GC Thread", ParallelGCThreads, 1471 true /* are_GC_task_threads */, 1472 false /* are_ConcurrentGC_threads */); 1473 _workers->initialize_workers(); 1474 _verifier = new G1HeapVerifier(this); 1475 1476 _allocator = new G1Allocator(this); 1477 1478 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics()); 1479 1480 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords); 1481 1482 // Override the default _filler_array_max_size so that no humongous filler 1483 // objects are created. 1484 _filler_array_max_size = _humongous_object_threshold_in_words; 1485 1486 uint n_queues = ParallelGCThreads; 1487 _task_queues = new RefToScanQueueSet(n_queues); 1488 1489 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC); 1490 1491 for (uint i = 0; i < n_queues; i++) { 1492 RefToScanQueue* q = new RefToScanQueue(); 1493 q->initialize(); 1494 _task_queues->register_queue(i, q); 1495 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo(); 1496 } 1497 1498 // Initialize the G1EvacuationFailureALot counters and flags. 1499 NOT_PRODUCT(reset_evacuation_should_fail();) 1500 1501 guarantee(_task_queues != NULL, "task_queues allocation failure."); 1502 } 1503 1504 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description, 1505 size_t size, 1506 size_t translation_factor) { 1507 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1); 1508 // Allocate a new reserved space, preferring to use large pages. 1509 ReservedSpace rs(size, preferred_page_size); 1510 G1RegionToSpaceMapper* result = 1511 G1RegionToSpaceMapper::create_mapper(rs, 1512 size, 1513 rs.alignment(), 1514 HeapRegion::GrainBytes, 1515 translation_factor, 1516 mtGC); 1517 1518 os::trace_page_sizes_for_requested_size(description, 1519 size, 1520 preferred_page_size, 1521 rs.alignment(), 1522 rs.base(), 1523 rs.size()); 1524 1525 return result; 1526 } 1527 1528 jint G1CollectedHeap::initialize_concurrent_refinement() { 1529 jint ecode = JNI_OK; 1530 _cr = G1ConcurrentRefine::create(&ecode); 1531 return ecode; 1532 } 1533 1534 jint G1CollectedHeap::initialize_young_gen_sampling_thread() { 1535 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread(); 1536 if (_young_gen_sampling_thread->osthread() == NULL) { 1537 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread"); 1538 return JNI_ENOMEM; 1539 } 1540 return JNI_OK; 1541 } 1542 1543 jint G1CollectedHeap::initialize() { 1544 os::enable_vtime(); 1545 1546 // Necessary to satisfy locking discipline assertions. 1547 1548 MutexLocker x(Heap_lock); 1549 1550 // While there are no constraints in the GC code that HeapWordSize 1551 // be any particular value, there are multiple other areas in the 1552 // system which believe this to be true (e.g. oop->object_size in some 1553 // cases incorrectly returns the size in wordSize units rather than 1554 // HeapWordSize). 1555 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 1556 1557 size_t init_byte_size = collector_policy()->initial_heap_byte_size(); 1558 size_t max_byte_size = collector_policy()->max_heap_byte_size(); 1559 size_t heap_alignment = collector_policy()->heap_alignment(); 1560 1561 // Ensure that the sizes are properly aligned. 1562 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1563 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1564 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap"); 1565 1566 // Reserve the maximum. 1567 1568 // When compressed oops are enabled, the preferred heap base 1569 // is calculated by subtracting the requested size from the 1570 // 32Gb boundary and using the result as the base address for 1571 // heap reservation. If the requested size is not aligned to 1572 // HeapRegion::GrainBytes (i.e. the alignment that is passed 1573 // into the ReservedHeapSpace constructor) then the actual 1574 // base of the reserved heap may end up differing from the 1575 // address that was requested (i.e. the preferred heap base). 1576 // If this happens then we could end up using a non-optimal 1577 // compressed oops mode. 1578 1579 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size, 1580 heap_alignment); 1581 1582 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size())); 1583 1584 // Create the barrier set for the entire reserved region. 1585 G1CardTable* ct = new G1CardTable(reserved_region()); 1586 ct->initialize(); 1587 G1BarrierSet* bs = new G1BarrierSet(ct); 1588 bs->initialize(); 1589 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity"); 1590 BarrierSet::set_barrier_set(bs); 1591 _card_table = ct; 1592 1593 // Create the hot card cache. 1594 _hot_card_cache = new G1HotCardCache(this); 1595 1596 // Carve out the G1 part of the heap. 1597 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size); 1598 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size(); 1599 G1RegionToSpaceMapper* heap_storage = 1600 G1RegionToSpaceMapper::create_mapper(g1_rs, 1601 g1_rs.size(), 1602 page_size, 1603 HeapRegion::GrainBytes, 1604 1, 1605 mtJavaHeap); 1606 os::trace_page_sizes("Heap", 1607 collector_policy()->min_heap_byte_size(), 1608 max_byte_size, 1609 page_size, 1610 heap_rs.base(), 1611 heap_rs.size()); 1612 heap_storage->set_mapping_changed_listener(&_listener); 1613 1614 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps. 1615 G1RegionToSpaceMapper* bot_storage = 1616 create_aux_memory_mapper("Block Offset Table", 1617 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize), 1618 G1BlockOffsetTable::heap_map_factor()); 1619 1620 G1RegionToSpaceMapper* cardtable_storage = 1621 create_aux_memory_mapper("Card Table", 1622 G1CardTable::compute_size(g1_rs.size() / HeapWordSize), 1623 G1CardTable::heap_map_factor()); 1624 1625 G1RegionToSpaceMapper* card_counts_storage = 1626 create_aux_memory_mapper("Card Counts Table", 1627 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize), 1628 G1CardCounts::heap_map_factor()); 1629 1630 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size()); 1631 G1RegionToSpaceMapper* prev_bitmap_storage = 1632 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1633 G1RegionToSpaceMapper* next_bitmap_storage = 1634 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1635 1636 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage); 1637 _card_table->initialize(cardtable_storage); 1638 // Do later initialization work for concurrent refinement. 1639 _hot_card_cache->initialize(card_counts_storage); 1640 1641 // 6843694 - ensure that the maximum region index can fit 1642 // in the remembered set structures. 1643 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; 1644 guarantee((max_regions() - 1) <= max_region_idx, "too many regions"); 1645 1646 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not 1647 // start within the first card. 1648 guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card."); 1649 // Also create a G1 rem set. 1650 _g1_rem_set = new G1RemSet(this, _card_table, _hot_card_cache); 1651 _g1_rem_set->initialize(max_capacity(), max_regions()); 1652 1653 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; 1654 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); 1655 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region, 1656 "too many cards per region"); 1657 1658 FreeRegionList::set_unrealistically_long_length(max_regions() + 1); 1659 1660 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage); 1661 1662 { 1663 HeapWord* start = _hrm.reserved().start(); 1664 HeapWord* end = _hrm.reserved().end(); 1665 size_t granularity = HeapRegion::GrainBytes; 1666 1667 _in_cset_fast_test.initialize(start, end, granularity); 1668 _humongous_reclaim_candidates.initialize(start, end, granularity); 1669 } 1670 1671 // Create the G1ConcurrentMark data structure and thread. 1672 // (Must do this late, so that "max_regions" is defined.) 1673 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage); 1674 if (_cm == NULL || !_cm->completed_initialization()) { 1675 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark"); 1676 return JNI_ENOMEM; 1677 } 1678 _cm_thread = _cm->cm_thread(); 1679 1680 // Now expand into the initial heap size. 1681 if (!expand(init_byte_size, _workers)) { 1682 vm_shutdown_during_initialization("Failed to allocate initial heap."); 1683 return JNI_ENOMEM; 1684 } 1685 1686 // Perform any initialization actions delegated to the policy. 1687 g1_policy()->init(this, &_collection_set); 1688 1689 G1BarrierSet::satb_mark_queue_set().initialize(this, 1690 SATB_Q_CBL_mon, 1691 SATB_Q_FL_lock, 1692 G1SATBProcessCompletedThreshold, 1693 G1SATBBufferEnqueueingThresholdPercent, 1694 Shared_SATB_Q_lock); 1695 1696 jint ecode = initialize_concurrent_refinement(); 1697 if (ecode != JNI_OK) { 1698 return ecode; 1699 } 1700 1701 ecode = initialize_young_gen_sampling_thread(); 1702 if (ecode != JNI_OK) { 1703 return ecode; 1704 } 1705 1706 G1BarrierSet::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon, 1707 DirtyCardQ_FL_lock, 1708 (int)concurrent_refine()->yellow_zone(), 1709 (int)concurrent_refine()->red_zone(), 1710 Shared_DirtyCardQ_lock, 1711 NULL, // fl_owner 1712 true); // init_free_ids 1713 1714 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon, 1715 DirtyCardQ_FL_lock, 1716 -1, // never trigger processing 1717 -1, // no limit on length 1718 Shared_DirtyCardQ_lock, 1719 &G1BarrierSet::dirty_card_queue_set()); 1720 1721 // Here we allocate the dummy HeapRegion that is required by the 1722 // G1AllocRegion class. 1723 HeapRegion* dummy_region = _hrm.get_dummy_region(); 1724 1725 // We'll re-use the same region whether the alloc region will 1726 // require BOT updates or not and, if it doesn't, then a non-young 1727 // region will complain that it cannot support allocations without 1728 // BOT updates. So we'll tag the dummy region as eden to avoid that. 1729 dummy_region->set_eden(); 1730 // Make sure it's full. 1731 dummy_region->set_top(dummy_region->end()); 1732 G1AllocRegion::setup(this, dummy_region); 1733 1734 _allocator->init_mutator_alloc_region(); 1735 1736 // Do create of the monitoring and management support so that 1737 // values in the heap have been properly initialized. 1738 _g1mm = new G1MonitoringSupport(this); 1739 1740 G1StringDedup::initialize(); 1741 1742 _preserved_marks_set.init(ParallelGCThreads); 1743 1744 _collection_set.initialize(max_regions()); 1745 1746 return JNI_OK; 1747 } 1748 1749 void G1CollectedHeap::initialize_serviceability() { 1750 _eden_pool = new G1EdenPool(this); 1751 _survivor_pool = new G1SurvivorPool(this); 1752 _old_pool = new G1OldGenPool(this); 1753 1754 _full_gc_memory_manager.add_pool(_eden_pool); 1755 _full_gc_memory_manager.add_pool(_survivor_pool); 1756 _full_gc_memory_manager.add_pool(_old_pool); 1757 1758 _memory_manager.add_pool(_eden_pool); 1759 _memory_manager.add_pool(_survivor_pool); 1760 _memory_manager.add_pool(_old_pool, false /* always_affected_by_gc */); 1761 } 1762 1763 void G1CollectedHeap::stop() { 1764 // Stop all concurrent threads. We do this to make sure these threads 1765 // do not continue to execute and access resources (e.g. logging) 1766 // that are destroyed during shutdown. 1767 _cr->stop(); 1768 _young_gen_sampling_thread->stop(); 1769 _cm_thread->stop(); 1770 if (G1StringDedup::is_enabled()) { 1771 G1StringDedup::stop(); 1772 } 1773 } 1774 1775 void G1CollectedHeap::safepoint_synchronize_begin() { 1776 SuspendibleThreadSet::synchronize(); 1777 } 1778 1779 void G1CollectedHeap::safepoint_synchronize_end() { 1780 SuspendibleThreadSet::desynchronize(); 1781 } 1782 1783 size_t G1CollectedHeap::conservative_max_heap_alignment() { 1784 return HeapRegion::max_region_size(); 1785 } 1786 1787 void G1CollectedHeap::post_initialize() { 1788 CollectedHeap::post_initialize(); 1789 ref_processing_init(); 1790 } 1791 1792 void G1CollectedHeap::ref_processing_init() { 1793 // Reference processing in G1 currently works as follows: 1794 // 1795 // * There are two reference processor instances. One is 1796 // used to record and process discovered references 1797 // during concurrent marking; the other is used to 1798 // record and process references during STW pauses 1799 // (both full and incremental). 1800 // * Both ref processors need to 'span' the entire heap as 1801 // the regions in the collection set may be dotted around. 1802 // 1803 // * For the concurrent marking ref processor: 1804 // * Reference discovery is enabled at initial marking. 1805 // * Reference discovery is disabled and the discovered 1806 // references processed etc during remarking. 1807 // * Reference discovery is MT (see below). 1808 // * Reference discovery requires a barrier (see below). 1809 // * Reference processing may or may not be MT 1810 // (depending on the value of ParallelRefProcEnabled 1811 // and ParallelGCThreads). 1812 // * A full GC disables reference discovery by the CM 1813 // ref processor and abandons any entries on it's 1814 // discovered lists. 1815 // 1816 // * For the STW processor: 1817 // * Non MT discovery is enabled at the start of a full GC. 1818 // * Processing and enqueueing during a full GC is non-MT. 1819 // * During a full GC, references are processed after marking. 1820 // 1821 // * Discovery (may or may not be MT) is enabled at the start 1822 // of an incremental evacuation pause. 1823 // * References are processed near the end of a STW evacuation pause. 1824 // * For both types of GC: 1825 // * Discovery is atomic - i.e. not concurrent. 1826 // * Reference discovery will not need a barrier. 1827 1828 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1); 1829 1830 // Concurrent Mark ref processor 1831 _ref_processor_cm = 1832 new ReferenceProcessor(&_is_subject_to_discovery_cm, 1833 mt_processing, // mt processing 1834 ParallelGCThreads, // degree of mt processing 1835 (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery 1836 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery 1837 false, // Reference discovery is not atomic 1838 &_is_alive_closure_cm, // is alive closure 1839 true); // allow changes to number of processing threads 1840 1841 // STW ref processor 1842 _ref_processor_stw = 1843 new ReferenceProcessor(&_is_subject_to_discovery_stw, 1844 mt_processing, // mt processing 1845 ParallelGCThreads, // degree of mt processing 1846 (ParallelGCThreads > 1), // mt discovery 1847 ParallelGCThreads, // degree of mt discovery 1848 true, // Reference discovery is atomic 1849 &_is_alive_closure_stw, // is alive closure 1850 true); // allow changes to number of processing threads 1851 } 1852 1853 CollectorPolicy* G1CollectedHeap::collector_policy() const { 1854 return _collector_policy; 1855 } 1856 1857 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() { 1858 return &_soft_ref_policy; 1859 } 1860 1861 size_t G1CollectedHeap::capacity() const { 1862 return _hrm.length() * HeapRegion::GrainBytes; 1863 } 1864 1865 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const { 1866 return _hrm.total_free_bytes(); 1867 } 1868 1869 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) { 1870 _hot_card_cache->drain(cl, worker_i); 1871 } 1872 1873 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) { 1874 DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set(); 1875 size_t n_completed_buffers = 0; 1876 while (dcqs.apply_closure_during_gc(cl, worker_i)) { 1877 n_completed_buffers++; 1878 } 1879 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers, G1GCPhaseTimes::UpdateRSProcessedBuffers); 1880 dcqs.clear_n_completed_buffers(); 1881 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!"); 1882 } 1883 1884 // Computes the sum of the storage used by the various regions. 1885 size_t G1CollectedHeap::used() const { 1886 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions(); 1887 if (_archive_allocator != NULL) { 1888 result += _archive_allocator->used(); 1889 } 1890 return result; 1891 } 1892 1893 size_t G1CollectedHeap::used_unlocked() const { 1894 return _summary_bytes_used; 1895 } 1896 1897 class SumUsedClosure: public HeapRegionClosure { 1898 size_t _used; 1899 public: 1900 SumUsedClosure() : _used(0) {} 1901 bool do_heap_region(HeapRegion* r) { 1902 _used += r->used(); 1903 return false; 1904 } 1905 size_t result() { return _used; } 1906 }; 1907 1908 size_t G1CollectedHeap::recalculate_used() const { 1909 double recalculate_used_start = os::elapsedTime(); 1910 1911 SumUsedClosure blk; 1912 heap_region_iterate(&blk); 1913 1914 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0); 1915 return blk.result(); 1916 } 1917 1918 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) { 1919 switch (cause) { 1920 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent; 1921 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent; 1922 case GCCause::_wb_conc_mark: return true; 1923 default : return false; 1924 } 1925 } 1926 1927 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 1928 switch (cause) { 1929 case GCCause::_gc_locker: return GCLockerInvokesConcurrent; 1930 case GCCause::_g1_humongous_allocation: return true; 1931 default: return is_user_requested_concurrent_full_gc(cause); 1932 } 1933 } 1934 1935 #ifndef PRODUCT 1936 void G1CollectedHeap::allocate_dummy_regions() { 1937 // Let's fill up most of the region 1938 size_t word_size = HeapRegion::GrainWords - 1024; 1939 // And as a result the region we'll allocate will be humongous. 1940 guarantee(is_humongous(word_size), "sanity"); 1941 1942 // _filler_array_max_size is set to humongous object threshold 1943 // but temporarily change it to use CollectedHeap::fill_with_object(). 1944 SizeTFlagSetting fs(_filler_array_max_size, word_size); 1945 1946 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) { 1947 // Let's use the existing mechanism for the allocation 1948 HeapWord* dummy_obj = humongous_obj_allocate(word_size); 1949 if (dummy_obj != NULL) { 1950 MemRegion mr(dummy_obj, word_size); 1951 CollectedHeap::fill_with_object(mr); 1952 } else { 1953 // If we can't allocate once, we probably cannot allocate 1954 // again. Let's get out of the loop. 1955 break; 1956 } 1957 } 1958 } 1959 #endif // !PRODUCT 1960 1961 void G1CollectedHeap::increment_old_marking_cycles_started() { 1962 assert(_old_marking_cycles_started == _old_marking_cycles_completed || 1963 _old_marking_cycles_started == _old_marking_cycles_completed + 1, 1964 "Wrong marking cycle count (started: %d, completed: %d)", 1965 _old_marking_cycles_started, _old_marking_cycles_completed); 1966 1967 _old_marking_cycles_started++; 1968 } 1969 1970 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) { 1971 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 1972 1973 // We assume that if concurrent == true, then the caller is a 1974 // concurrent thread that was joined the Suspendible Thread 1975 // Set. If there's ever a cheap way to check this, we should add an 1976 // assert here. 1977 1978 // Given that this method is called at the end of a Full GC or of a 1979 // concurrent cycle, and those can be nested (i.e., a Full GC can 1980 // interrupt a concurrent cycle), the number of full collections 1981 // completed should be either one (in the case where there was no 1982 // nesting) or two (when a Full GC interrupted a concurrent cycle) 1983 // behind the number of full collections started. 1984 1985 // This is the case for the inner caller, i.e. a Full GC. 1986 assert(concurrent || 1987 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || 1988 (_old_marking_cycles_started == _old_marking_cycles_completed + 2), 1989 "for inner caller (Full GC): _old_marking_cycles_started = %u " 1990 "is inconsistent with _old_marking_cycles_completed = %u", 1991 _old_marking_cycles_started, _old_marking_cycles_completed); 1992 1993 // This is the case for the outer caller, i.e. the concurrent cycle. 1994 assert(!concurrent || 1995 (_old_marking_cycles_started == _old_marking_cycles_completed + 1), 1996 "for outer caller (concurrent cycle): " 1997 "_old_marking_cycles_started = %u " 1998 "is inconsistent with _old_marking_cycles_completed = %u", 1999 _old_marking_cycles_started, _old_marking_cycles_completed); 2000 2001 _old_marking_cycles_completed += 1; 2002 2003 // We need to clear the "in_progress" flag in the CM thread before 2004 // we wake up any waiters (especially when ExplicitInvokesConcurrent 2005 // is set) so that if a waiter requests another System.gc() it doesn't 2006 // incorrectly see that a marking cycle is still in progress. 2007 if (concurrent) { 2008 _cm_thread->set_idle(); 2009 } 2010 2011 // This notify_all() will ensure that a thread that called 2012 // System.gc() with (with ExplicitGCInvokesConcurrent set or not) 2013 // and it's waiting for a full GC to finish will be woken up. It is 2014 // waiting in VM_G1CollectForAllocation::doit_epilogue(). 2015 FullGCCount_lock->notify_all(); 2016 } 2017 2018 void G1CollectedHeap::collect(GCCause::Cause cause) { 2019 assert_heap_not_locked(); 2020 2021 uint gc_count_before; 2022 uint old_marking_count_before; 2023 uint full_gc_count_before; 2024 bool retry_gc; 2025 2026 do { 2027 retry_gc = false; 2028 2029 { 2030 MutexLocker ml(Heap_lock); 2031 2032 // Read the GC count while holding the Heap_lock 2033 gc_count_before = total_collections(); 2034 full_gc_count_before = total_full_collections(); 2035 old_marking_count_before = _old_marking_cycles_started; 2036 } 2037 2038 if (should_do_concurrent_full_gc(cause)) { 2039 // Schedule an initial-mark evacuation pause that will start a 2040 // concurrent cycle. We're setting word_size to 0 which means that 2041 // we are not requesting a post-GC allocation. 2042 VM_G1CollectForAllocation op(0, /* word_size */ 2043 gc_count_before, 2044 cause, 2045 true, /* should_initiate_conc_mark */ 2046 g1_policy()->max_pause_time_ms()); 2047 VMThread::execute(&op); 2048 if (!op.pause_succeeded()) { 2049 if (old_marking_count_before == _old_marking_cycles_started) { 2050 retry_gc = op.should_retry_gc(); 2051 } else { 2052 // A Full GC happened while we were trying to schedule the 2053 // initial-mark GC. No point in starting a new cycle given 2054 // that the whole heap was collected anyway. 2055 } 2056 2057 if (retry_gc) { 2058 if (GCLocker::is_active_and_needs_gc()) { 2059 GCLocker::stall_until_clear(); 2060 } 2061 } 2062 } 2063 } else { 2064 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc 2065 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { 2066 2067 // Schedule a standard evacuation pause. We're setting word_size 2068 // to 0 which means that we are not requesting a post-GC allocation. 2069 VM_G1CollectForAllocation op(0, /* word_size */ 2070 gc_count_before, 2071 cause, 2072 false, /* should_initiate_conc_mark */ 2073 g1_policy()->max_pause_time_ms()); 2074 VMThread::execute(&op); 2075 } else { 2076 // Schedule a Full GC. 2077 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause); 2078 VMThread::execute(&op); 2079 } 2080 } 2081 } while (retry_gc); 2082 } 2083 2084 bool G1CollectedHeap::is_in(const void* p) const { 2085 if (_hrm.reserved().contains(p)) { 2086 // Given that we know that p is in the reserved space, 2087 // heap_region_containing() should successfully 2088 // return the containing region. 2089 HeapRegion* hr = heap_region_containing(p); 2090 return hr->is_in(p); 2091 } else { 2092 return false; 2093 } 2094 } 2095 2096 #ifdef ASSERT 2097 bool G1CollectedHeap::is_in_exact(const void* p) const { 2098 bool contains = reserved_region().contains(p); 2099 bool available = _hrm.is_available(addr_to_region((HeapWord*)p)); 2100 if (contains && available) { 2101 return true; 2102 } else { 2103 return false; 2104 } 2105 } 2106 #endif 2107 2108 // Iteration functions. 2109 2110 // Iterates an ObjectClosure over all objects within a HeapRegion. 2111 2112 class IterateObjectClosureRegionClosure: public HeapRegionClosure { 2113 ObjectClosure* _cl; 2114 public: 2115 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} 2116 bool do_heap_region(HeapRegion* r) { 2117 if (!r->is_continues_humongous()) { 2118 r->object_iterate(_cl); 2119 } 2120 return false; 2121 } 2122 }; 2123 2124 void G1CollectedHeap::object_iterate(ObjectClosure* cl) { 2125 IterateObjectClosureRegionClosure blk(cl); 2126 heap_region_iterate(&blk); 2127 } 2128 2129 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { 2130 _hrm.iterate(cl); 2131 } 2132 2133 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl, 2134 HeapRegionClaimer *hrclaimer, 2135 uint worker_id) const { 2136 _hrm.par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id)); 2137 } 2138 2139 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl, 2140 HeapRegionClaimer *hrclaimer) const { 2141 _hrm.par_iterate(cl, hrclaimer, 0); 2142 } 2143 2144 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) { 2145 _collection_set.iterate(cl); 2146 } 2147 2148 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) { 2149 _collection_set.iterate_from(cl, worker_id, workers()->active_workers()); 2150 } 2151 2152 HeapWord* G1CollectedHeap::block_start(const void* addr) const { 2153 HeapRegion* hr = heap_region_containing(addr); 2154 return hr->block_start(addr); 2155 } 2156 2157 size_t G1CollectedHeap::block_size(const HeapWord* addr) const { 2158 HeapRegion* hr = heap_region_containing(addr); 2159 return hr->block_size(addr); 2160 } 2161 2162 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { 2163 HeapRegion* hr = heap_region_containing(addr); 2164 return hr->block_is_obj(addr); 2165 } 2166 2167 bool G1CollectedHeap::supports_tlab_allocation() const { 2168 return true; 2169 } 2170 2171 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { 2172 return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes; 2173 } 2174 2175 size_t G1CollectedHeap::tlab_used(Thread* ignored) const { 2176 return _eden.length() * HeapRegion::GrainBytes; 2177 } 2178 2179 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size 2180 // must be equal to the humongous object limit. 2181 size_t G1CollectedHeap::max_tlab_size() const { 2182 return align_down(_humongous_object_threshold_in_words, MinObjAlignment); 2183 } 2184 2185 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { 2186 return _allocator->unsafe_max_tlab_alloc(); 2187 } 2188 2189 size_t G1CollectedHeap::max_capacity() const { 2190 return _hrm.reserved().byte_size(); 2191 } 2192 2193 jlong G1CollectedHeap::millis_since_last_gc() { 2194 // See the notes in GenCollectedHeap::millis_since_last_gc() 2195 // for more information about the implementation. 2196 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) - 2197 _g1_policy->collection_pause_end_millis(); 2198 if (ret_val < 0) { 2199 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT 2200 ". returning zero instead.", ret_val); 2201 return 0; 2202 } 2203 return ret_val; 2204 } 2205 2206 void G1CollectedHeap::deduplicate_string(oop str) { 2207 assert(java_lang_String::is_instance(str), "invariant"); 2208 2209 if (G1StringDedup::is_enabled()) { 2210 G1StringDedup::deduplicate(str); 2211 } 2212 } 2213 2214 void G1CollectedHeap::prepare_for_verify() { 2215 _verifier->prepare_for_verify(); 2216 } 2217 2218 void G1CollectedHeap::verify(VerifyOption vo) { 2219 _verifier->verify(vo); 2220 } 2221 2222 bool G1CollectedHeap::supports_concurrent_phase_control() const { 2223 return true; 2224 } 2225 2226 const char* const* G1CollectedHeap::concurrent_phases() const { 2227 return _cm_thread->concurrent_phases(); 2228 } 2229 2230 bool G1CollectedHeap::request_concurrent_phase(const char* phase) { 2231 return _cm_thread->request_concurrent_phase(phase); 2232 } 2233 2234 class PrintRegionClosure: public HeapRegionClosure { 2235 outputStream* _st; 2236 public: 2237 PrintRegionClosure(outputStream* st) : _st(st) {} 2238 bool do_heap_region(HeapRegion* r) { 2239 r->print_on(_st); 2240 return false; 2241 } 2242 }; 2243 2244 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2245 const HeapRegion* hr, 2246 const VerifyOption vo) const { 2247 switch (vo) { 2248 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); 2249 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); 2250 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr); 2251 default: ShouldNotReachHere(); 2252 } 2253 return false; // keep some compilers happy 2254 } 2255 2256 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2257 const VerifyOption vo) const { 2258 switch (vo) { 2259 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); 2260 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); 2261 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj); 2262 default: ShouldNotReachHere(); 2263 } 2264 return false; // keep some compilers happy 2265 } 2266 2267 void G1CollectedHeap::print_heap_regions() const { 2268 LogTarget(Trace, gc, heap, region) lt; 2269 if (lt.is_enabled()) { 2270 LogStream ls(lt); 2271 print_regions_on(&ls); 2272 } 2273 } 2274 2275 void G1CollectedHeap::print_on(outputStream* st) const { 2276 st->print(" %-20s", "garbage-first heap"); 2277 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 2278 capacity()/K, used_unlocked()/K); 2279 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")", 2280 p2i(_hrm.reserved().start()), 2281 p2i(_hrm.reserved().end())); 2282 st->cr(); 2283 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); 2284 uint young_regions = young_regions_count(); 2285 st->print("%u young (" SIZE_FORMAT "K), ", young_regions, 2286 (size_t) young_regions * HeapRegion::GrainBytes / K); 2287 uint survivor_regions = survivor_regions_count(); 2288 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, 2289 (size_t) survivor_regions * HeapRegion::GrainBytes / K); 2290 st->cr(); 2291 MetaspaceUtils::print_on(st); 2292 } 2293 2294 void G1CollectedHeap::print_regions_on(outputStream* st) const { 2295 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, " 2296 "HS=humongous(starts), HC=humongous(continues), " 2297 "CS=collection set, F=free, A=archive, " 2298 "TAMS=top-at-mark-start (previous, next)"); 2299 PrintRegionClosure blk(st); 2300 heap_region_iterate(&blk); 2301 } 2302 2303 void G1CollectedHeap::print_extended_on(outputStream* st) const { 2304 print_on(st); 2305 2306 // Print the per-region information. 2307 print_regions_on(st); 2308 } 2309 2310 void G1CollectedHeap::print_on_error(outputStream* st) const { 2311 this->CollectedHeap::print_on_error(st); 2312 2313 if (_cm != NULL) { 2314 st->cr(); 2315 _cm->print_on_error(st); 2316 } 2317 } 2318 2319 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const { 2320 workers()->print_worker_threads_on(st); 2321 _cm_thread->print_on(st); 2322 st->cr(); 2323 _cm->print_worker_threads_on(st); 2324 _cr->print_threads_on(st); 2325 _young_gen_sampling_thread->print_on(st); 2326 if (G1StringDedup::is_enabled()) { 2327 G1StringDedup::print_worker_threads_on(st); 2328 } 2329 } 2330 2331 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { 2332 workers()->threads_do(tc); 2333 tc->do_thread(_cm_thread); 2334 _cm->threads_do(tc); 2335 _cr->threads_do(tc); 2336 tc->do_thread(_young_gen_sampling_thread); 2337 if (G1StringDedup::is_enabled()) { 2338 G1StringDedup::threads_do(tc); 2339 } 2340 } 2341 2342 void G1CollectedHeap::print_tracing_info() const { 2343 g1_rem_set()->print_summary_info(); 2344 concurrent_mark()->print_summary_info(); 2345 } 2346 2347 #ifndef PRODUCT 2348 // Helpful for debugging RSet issues. 2349 2350 class PrintRSetsClosure : public HeapRegionClosure { 2351 private: 2352 const char* _msg; 2353 size_t _occupied_sum; 2354 2355 public: 2356 bool do_heap_region(HeapRegion* r) { 2357 HeapRegionRemSet* hrrs = r->rem_set(); 2358 size_t occupied = hrrs->occupied(); 2359 _occupied_sum += occupied; 2360 2361 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r)); 2362 if (occupied == 0) { 2363 tty->print_cr(" RSet is empty"); 2364 } else { 2365 hrrs->print(); 2366 } 2367 tty->print_cr("----------"); 2368 return false; 2369 } 2370 2371 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { 2372 tty->cr(); 2373 tty->print_cr("========================================"); 2374 tty->print_cr("%s", msg); 2375 tty->cr(); 2376 } 2377 2378 ~PrintRSetsClosure() { 2379 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum); 2380 tty->print_cr("========================================"); 2381 tty->cr(); 2382 } 2383 }; 2384 2385 void G1CollectedHeap::print_cset_rsets() { 2386 PrintRSetsClosure cl("Printing CSet RSets"); 2387 collection_set_iterate(&cl); 2388 } 2389 2390 void G1CollectedHeap::print_all_rsets() { 2391 PrintRSetsClosure cl("Printing All RSets");; 2392 heap_region_iterate(&cl); 2393 } 2394 #endif // PRODUCT 2395 2396 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() { 2397 2398 size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes; 2399 size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes; 2400 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked(); 2401 2402 size_t eden_capacity_bytes = 2403 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes; 2404 2405 VirtualSpaceSummary heap_summary = create_heap_space_summary(); 2406 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes, 2407 eden_capacity_bytes, survivor_used_bytes, num_regions()); 2408 } 2409 2410 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) { 2411 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(), 2412 stats->unused(), stats->used(), stats->region_end_waste(), 2413 stats->regions_filled(), stats->direct_allocated(), 2414 stats->failure_used(), stats->failure_waste()); 2415 } 2416 2417 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) { 2418 const G1HeapSummary& heap_summary = create_g1_heap_summary(); 2419 gc_tracer->report_gc_heap_summary(when, heap_summary); 2420 2421 const MetaspaceSummary& metaspace_summary = create_metaspace_summary(); 2422 gc_tracer->report_metaspace_summary(when, metaspace_summary); 2423 } 2424 2425 G1CollectedHeap* G1CollectedHeap::heap() { 2426 CollectedHeap* heap = Universe::heap(); 2427 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()"); 2428 assert(heap->kind() == CollectedHeap::G1, "Invalid name"); 2429 return (G1CollectedHeap*)heap; 2430 } 2431 2432 void G1CollectedHeap::gc_prologue(bool full) { 2433 // always_do_update_barrier = false; 2434 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 2435 2436 // This summary needs to be printed before incrementing total collections. 2437 g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections()); 2438 2439 // Update common counters. 2440 increment_total_collections(full /* full gc */); 2441 if (full) { 2442 increment_old_marking_cycles_started(); 2443 } 2444 2445 // Fill TLAB's and such 2446 double start = os::elapsedTime(); 2447 accumulate_statistics_all_tlabs(); 2448 ensure_parsability(true); 2449 g1_policy()->phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0); 2450 } 2451 2452 void G1CollectedHeap::gc_epilogue(bool full) { 2453 // Update common counters. 2454 if (full) { 2455 // Update the number of full collections that have been completed. 2456 increment_old_marking_cycles_completed(false /* concurrent */); 2457 } 2458 2459 // We are at the end of the GC. Total collections has already been increased. 2460 g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1); 2461 2462 // FIXME: what is this about? 2463 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" 2464 // is set. 2465 #if COMPILER2_OR_JVMCI 2466 assert(DerivedPointerTable::is_empty(), "derived pointer present"); 2467 #endif 2468 // always_do_update_barrier = true; 2469 2470 double start = os::elapsedTime(); 2471 resize_all_tlabs(); 2472 g1_policy()->phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0); 2473 2474 MemoryService::track_memory_usage(); 2475 // We have just completed a GC. Update the soft reference 2476 // policy with the new heap occupancy 2477 Universe::update_heap_info_at_gc(); 2478 } 2479 2480 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, 2481 uint gc_count_before, 2482 bool* succeeded, 2483 GCCause::Cause gc_cause) { 2484 assert_heap_not_locked_and_not_at_safepoint(); 2485 VM_G1CollectForAllocation op(word_size, 2486 gc_count_before, 2487 gc_cause, 2488 false, /* should_initiate_conc_mark */ 2489 g1_policy()->max_pause_time_ms()); 2490 VMThread::execute(&op); 2491 2492 HeapWord* result = op.result(); 2493 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded(); 2494 assert(result == NULL || ret_succeeded, 2495 "the result should be NULL if the VM did not succeed"); 2496 *succeeded = ret_succeeded; 2497 2498 assert_heap_not_locked(); 2499 return result; 2500 } 2501 2502 void G1CollectedHeap::do_concurrent_mark() { 2503 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); 2504 if (!_cm_thread->in_progress()) { 2505 _cm_thread->set_started(); 2506 CGC_lock->notify(); 2507 } 2508 } 2509 2510 size_t G1CollectedHeap::pending_card_num() { 2511 size_t extra_cards = 0; 2512 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *curr = jtiwh.next(); ) { 2513 DirtyCardQueue& dcq = G1ThreadLocalData::dirty_card_queue(curr); 2514 extra_cards += dcq.size(); 2515 } 2516 DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set(); 2517 size_t buffer_size = dcqs.buffer_size(); 2518 size_t buffer_num = dcqs.completed_buffers_num(); 2519 2520 return buffer_size * buffer_num + extra_cards; 2521 } 2522 2523 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const { 2524 // We don't nominate objects with many remembered set entries, on 2525 // the assumption that such objects are likely still live. 2526 HeapRegionRemSet* rem_set = r->rem_set(); 2527 2528 return G1EagerReclaimHumongousObjectsWithStaleRefs ? 2529 rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) : 2530 G1EagerReclaimHumongousObjects && rem_set->is_empty(); 2531 } 2532 2533 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure { 2534 private: 2535 size_t _total_humongous; 2536 size_t _candidate_humongous; 2537 2538 DirtyCardQueue _dcq; 2539 2540 bool humongous_region_is_candidate(G1CollectedHeap* g1h, HeapRegion* region) const { 2541 assert(region->is_starts_humongous(), "Must start a humongous object"); 2542 2543 oop obj = oop(region->bottom()); 2544 2545 // Dead objects cannot be eager reclaim candidates. Due to class 2546 // unloading it is unsafe to query their classes so we return early. 2547 if (g1h->is_obj_dead(obj, region)) { 2548 return false; 2549 } 2550 2551 // If we do not have a complete remembered set for the region, then we can 2552 // not be sure that we have all references to it. 2553 if (!region->rem_set()->is_complete()) { 2554 return false; 2555 } 2556 // Candidate selection must satisfy the following constraints 2557 // while concurrent marking is in progress: 2558 // 2559 // * In order to maintain SATB invariants, an object must not be 2560 // reclaimed if it was allocated before the start of marking and 2561 // has not had its references scanned. Such an object must have 2562 // its references (including type metadata) scanned to ensure no 2563 // live objects are missed by the marking process. Objects 2564 // allocated after the start of concurrent marking don't need to 2565 // be scanned. 2566 // 2567 // * An object must not be reclaimed if it is on the concurrent 2568 // mark stack. Objects allocated after the start of concurrent 2569 // marking are never pushed on the mark stack. 2570 // 2571 // Nominating only objects allocated after the start of concurrent 2572 // marking is sufficient to meet both constraints. This may miss 2573 // some objects that satisfy the constraints, but the marking data 2574 // structures don't support efficiently performing the needed 2575 // additional tests or scrubbing of the mark stack. 2576 // 2577 // However, we presently only nominate is_typeArray() objects. 2578 // A humongous object containing references induces remembered 2579 // set entries on other regions. In order to reclaim such an 2580 // object, those remembered sets would need to be cleaned up. 2581 // 2582 // We also treat is_typeArray() objects specially, allowing them 2583 // to be reclaimed even if allocated before the start of 2584 // concurrent mark. For this we rely on mark stack insertion to 2585 // exclude is_typeArray() objects, preventing reclaiming an object 2586 // that is in the mark stack. We also rely on the metadata for 2587 // such objects to be built-in and so ensured to be kept live. 2588 // Frequent allocation and drop of large binary blobs is an 2589 // important use case for eager reclaim, and this special handling 2590 // may reduce needed headroom. 2591 2592 return obj->is_typeArray() && 2593 g1h->is_potential_eager_reclaim_candidate(region); 2594 } 2595 2596 public: 2597 RegisterHumongousWithInCSetFastTestClosure() 2598 : _total_humongous(0), 2599 _candidate_humongous(0), 2600 _dcq(&G1BarrierSet::dirty_card_queue_set()) { 2601 } 2602 2603 virtual bool do_heap_region(HeapRegion* r) { 2604 if (!r->is_starts_humongous()) { 2605 return false; 2606 } 2607 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 2608 2609 bool is_candidate = humongous_region_is_candidate(g1h, r); 2610 uint rindex = r->hrm_index(); 2611 g1h->set_humongous_reclaim_candidate(rindex, is_candidate); 2612 if (is_candidate) { 2613 _candidate_humongous++; 2614 g1h->register_humongous_region_with_cset(rindex); 2615 // Is_candidate already filters out humongous object with large remembered sets. 2616 // If we have a humongous object with a few remembered sets, we simply flush these 2617 // remembered set entries into the DCQS. That will result in automatic 2618 // re-evaluation of their remembered set entries during the following evacuation 2619 // phase. 2620 if (!r->rem_set()->is_empty()) { 2621 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries), 2622 "Found a not-small remembered set here. This is inconsistent with previous assumptions."); 2623 G1CardTable* ct = g1h->card_table(); 2624 HeapRegionRemSetIterator hrrs(r->rem_set()); 2625 size_t card_index; 2626 while (hrrs.has_next(card_index)) { 2627 jbyte* card_ptr = (jbyte*)ct->byte_for_index(card_index); 2628 // The remembered set might contain references to already freed 2629 // regions. Filter out such entries to avoid failing card table 2630 // verification. 2631 if (g1h->is_in_closed_subset(ct->addr_for(card_ptr))) { 2632 if (*card_ptr != G1CardTable::dirty_card_val()) { 2633 *card_ptr = G1CardTable::dirty_card_val(); 2634 _dcq.enqueue(card_ptr); 2635 } 2636 } 2637 } 2638 assert(hrrs.n_yielded() == r->rem_set()->occupied(), 2639 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries", 2640 hrrs.n_yielded(), r->rem_set()->occupied()); 2641 // We should only clear the card based remembered set here as we will not 2642 // implicitly rebuild anything else during eager reclaim. Note that at the moment 2643 // (and probably never) we do not enter this path if there are other kind of 2644 // remembered sets for this region. 2645 r->rem_set()->clear_locked(true /* only_cardset */); 2646 // Clear_locked() above sets the state to Empty. However we want to continue 2647 // collecting remembered set entries for humongous regions that were not 2648 // reclaimed. 2649 r->rem_set()->set_state_complete(); 2650 } 2651 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty."); 2652 } 2653 _total_humongous++; 2654 2655 return false; 2656 } 2657 2658 size_t total_humongous() const { return _total_humongous; } 2659 size_t candidate_humongous() const { return _candidate_humongous; } 2660 2661 void flush_rem_set_entries() { _dcq.flush(); } 2662 }; 2663 2664 void G1CollectedHeap::register_humongous_regions_with_cset() { 2665 if (!G1EagerReclaimHumongousObjects) { 2666 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0); 2667 return; 2668 } 2669 double time = os::elapsed_counter(); 2670 2671 // Collect reclaim candidate information and register candidates with cset. 2672 RegisterHumongousWithInCSetFastTestClosure cl; 2673 heap_region_iterate(&cl); 2674 2675 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0; 2676 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time, 2677 cl.total_humongous(), 2678 cl.candidate_humongous()); 2679 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0; 2680 2681 // Finally flush all remembered set entries to re-check into the global DCQS. 2682 cl.flush_rem_set_entries(); 2683 } 2684 2685 class VerifyRegionRemSetClosure : public HeapRegionClosure { 2686 public: 2687 bool do_heap_region(HeapRegion* hr) { 2688 if (!hr->is_archive() && !hr->is_continues_humongous()) { 2689 hr->verify_rem_set(); 2690 } 2691 return false; 2692 } 2693 }; 2694 2695 uint G1CollectedHeap::num_task_queues() const { 2696 return _task_queues->size(); 2697 } 2698 2699 #if TASKQUEUE_STATS 2700 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) { 2701 st->print_raw_cr("GC Task Stats"); 2702 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); 2703 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); 2704 } 2705 2706 void G1CollectedHeap::print_taskqueue_stats() const { 2707 if (!log_is_enabled(Trace, gc, task, stats)) { 2708 return; 2709 } 2710 Log(gc, task, stats) log; 2711 ResourceMark rm; 2712 LogStream ls(log.trace()); 2713 outputStream* st = &ls; 2714 2715 print_taskqueue_stats_hdr(st); 2716 2717 TaskQueueStats totals; 2718 const uint n = num_task_queues(); 2719 for (uint i = 0; i < n; ++i) { 2720 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr(); 2721 totals += task_queue(i)->stats; 2722 } 2723 st->print_raw("tot "); totals.print(st); st->cr(); 2724 2725 DEBUG_ONLY(totals.verify()); 2726 } 2727 2728 void G1CollectedHeap::reset_taskqueue_stats() { 2729 const uint n = num_task_queues(); 2730 for (uint i = 0; i < n; ++i) { 2731 task_queue(i)->stats.reset(); 2732 } 2733 } 2734 #endif // TASKQUEUE_STATS 2735 2736 void G1CollectedHeap::wait_for_root_region_scanning() { 2737 double scan_wait_start = os::elapsedTime(); 2738 // We have to wait until the CM threads finish scanning the 2739 // root regions as it's the only way to ensure that all the 2740 // objects on them have been correctly scanned before we start 2741 // moving them during the GC. 2742 bool waited = _cm->root_regions()->wait_until_scan_finished(); 2743 double wait_time_ms = 0.0; 2744 if (waited) { 2745 double scan_wait_end = os::elapsedTime(); 2746 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0; 2747 } 2748 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms); 2749 } 2750 2751 class G1PrintCollectionSetClosure : public HeapRegionClosure { 2752 private: 2753 G1HRPrinter* _hr_printer; 2754 public: 2755 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { } 2756 2757 virtual bool do_heap_region(HeapRegion* r) { 2758 _hr_printer->cset(r); 2759 return false; 2760 } 2761 }; 2762 2763 void G1CollectedHeap::start_new_collection_set() { 2764 collection_set()->start_incremental_building(); 2765 2766 clear_cset_fast_test(); 2767 2768 guarantee(_eden.length() == 0, "eden should have been cleared"); 2769 g1_policy()->transfer_survivors_to_cset(survivor()); 2770 } 2771 2772 bool 2773 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { 2774 assert_at_safepoint_on_vm_thread(); 2775 guarantee(!is_gc_active(), "collection is not reentrant"); 2776 2777 if (GCLocker::check_active_before_gc()) { 2778 return false; 2779 } 2780 2781 _gc_timer_stw->register_gc_start(); 2782 2783 GCIdMark gc_id_mark; 2784 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start()); 2785 2786 SvcGCMarker sgcm(SvcGCMarker::MINOR); 2787 ResourceMark rm; 2788 2789 g1_policy()->note_gc_start(); 2790 2791 wait_for_root_region_scanning(); 2792 2793 print_heap_before_gc(); 2794 print_heap_regions(); 2795 trace_heap_before_gc(_gc_tracer_stw); 2796 2797 _verifier->verify_region_sets_optional(); 2798 _verifier->verify_dirty_young_regions(); 2799 2800 // We should not be doing initial mark unless the conc mark thread is running 2801 if (!_cm_thread->should_terminate()) { 2802 // This call will decide whether this pause is an initial-mark 2803 // pause. If it is, in_initial_mark_gc() will return true 2804 // for the duration of this pause. 2805 g1_policy()->decide_on_conc_mark_initiation(); 2806 } 2807 2808 // We do not allow initial-mark to be piggy-backed on a mixed GC. 2809 assert(!collector_state()->in_initial_mark_gc() || 2810 collector_state()->in_young_only_phase(), "sanity"); 2811 2812 // We also do not allow mixed GCs during marking. 2813 assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity"); 2814 2815 // Record whether this pause is an initial mark. When the current 2816 // thread has completed its logging output and it's safe to signal 2817 // the CM thread, the flag's value in the policy has been reset. 2818 bool should_start_conc_mark = collector_state()->in_initial_mark_gc(); 2819 2820 // Inner scope for scope based logging, timers, and stats collection 2821 { 2822 EvacuationInfo evacuation_info; 2823 2824 if (collector_state()->in_initial_mark_gc()) { 2825 // We are about to start a marking cycle, so we increment the 2826 // full collection counter. 2827 increment_old_marking_cycles_started(); 2828 _cm->gc_tracer_cm()->set_gc_cause(gc_cause()); 2829 } 2830 2831 _gc_tracer_stw->report_yc_type(collector_state()->yc_type()); 2832 2833 GCTraceCPUTime tcpu; 2834 2835 G1HeapVerifier::G1VerifyType verify_type; 2836 FormatBuffer<> gc_string("Pause Young "); 2837 if (collector_state()->in_initial_mark_gc()) { 2838 gc_string.append("(Concurrent Start)"); 2839 verify_type = G1HeapVerifier::G1VerifyConcurrentStart; 2840 } else if (collector_state()->in_young_only_phase()) { 2841 if (collector_state()->in_young_gc_before_mixed()) { 2842 gc_string.append("(Prepare Mixed)"); 2843 } else { 2844 gc_string.append("(Normal)"); 2845 } 2846 verify_type = G1HeapVerifier::G1VerifyYoungNormal; 2847 } else { 2848 gc_string.append("(Mixed)"); 2849 verify_type = G1HeapVerifier::G1VerifyMixed; 2850 } 2851 GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true); 2852 2853 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 2854 workers()->active_workers(), 2855 Threads::number_of_non_daemon_threads()); 2856 active_workers = workers()->update_active_workers(active_workers); 2857 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers()); 2858 2859 TraceCollectorStats tcs(g1mm()->incremental_collection_counters()); 2860 TraceMemoryManagerStats tms(&_memory_manager, gc_cause(), 2861 collector_state()->yc_type() == Mixed /* allMemoryPoolsAffected */); 2862 2863 G1HeapTransition heap_transition(this); 2864 size_t heap_used_bytes_before_gc = used(); 2865 2866 // Don't dynamically change the number of GC threads this early. A value of 2867 // 0 is used to indicate serial work. When parallel work is done, 2868 // it will be set. 2869 2870 { // Call to jvmpi::post_class_unload_events must occur outside of active GC 2871 IsGCActiveMark x; 2872 2873 gc_prologue(false); 2874 2875 if (VerifyRememberedSets) { 2876 log_info(gc, verify)("[Verifying RemSets before GC]"); 2877 VerifyRegionRemSetClosure v_cl; 2878 heap_region_iterate(&v_cl); 2879 } 2880 2881 _verifier->verify_before_gc(verify_type); 2882 2883 _verifier->check_bitmaps("GC Start"); 2884 2885 #if COMPILER2_OR_JVMCI 2886 DerivedPointerTable::clear(); 2887 #endif 2888 2889 // Please see comment in g1CollectedHeap.hpp and 2890 // G1CollectedHeap::ref_processing_init() to see how 2891 // reference processing currently works in G1. 2892 2893 // Enable discovery in the STW reference processor 2894 _ref_processor_stw->enable_discovery(); 2895 2896 { 2897 // We want to temporarily turn off discovery by the 2898 // CM ref processor, if necessary, and turn it back on 2899 // on again later if we do. Using a scoped 2900 // NoRefDiscovery object will do this. 2901 NoRefDiscovery no_cm_discovery(_ref_processor_cm); 2902 2903 // Forget the current alloc region (we might even choose it to be part 2904 // of the collection set!). 2905 _allocator->release_mutator_alloc_region(); 2906 2907 // This timing is only used by the ergonomics to handle our pause target. 2908 // It is unclear why this should not include the full pause. We will 2909 // investigate this in CR 7178365. 2910 // 2911 // Preserving the old comment here if that helps the investigation: 2912 // 2913 // The elapsed time induced by the start time below deliberately elides 2914 // the possible verification above. 2915 double sample_start_time_sec = os::elapsedTime(); 2916 2917 g1_policy()->record_collection_pause_start(sample_start_time_sec); 2918 2919 if (collector_state()->in_initial_mark_gc()) { 2920 concurrent_mark()->pre_initial_mark(); 2921 } 2922 2923 g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor); 2924 2925 evacuation_info.set_collectionset_regions(collection_set()->region_length()); 2926 2927 // Make sure the remembered sets are up to date. This needs to be 2928 // done before register_humongous_regions_with_cset(), because the 2929 // remembered sets are used there to choose eager reclaim candidates. 2930 // If the remembered sets are not up to date we might miss some 2931 // entries that need to be handled. 2932 g1_rem_set()->cleanupHRRS(); 2933 2934 register_humongous_regions_with_cset(); 2935 2936 assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table."); 2937 2938 // We call this after finalize_cset() to 2939 // ensure that the CSet has been finalized. 2940 _cm->verify_no_cset_oops(); 2941 2942 if (_hr_printer.is_active()) { 2943 G1PrintCollectionSetClosure cl(&_hr_printer); 2944 _collection_set.iterate(&cl); 2945 } 2946 2947 // Initialize the GC alloc regions. 2948 _allocator->init_gc_alloc_regions(evacuation_info); 2949 2950 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length()); 2951 pre_evacuate_collection_set(); 2952 2953 // Actually do the work... 2954 evacuate_collection_set(&per_thread_states); 2955 2956 post_evacuate_collection_set(evacuation_info, &per_thread_states); 2957 2958 const size_t* surviving_young_words = per_thread_states.surviving_young_words(); 2959 free_collection_set(&_collection_set, evacuation_info, surviving_young_words); 2960 2961 eagerly_reclaim_humongous_regions(); 2962 2963 record_obj_copy_mem_stats(); 2964 _survivor_evac_stats.adjust_desired_plab_sz(); 2965 _old_evac_stats.adjust_desired_plab_sz(); 2966 2967 double start = os::elapsedTime(); 2968 start_new_collection_set(); 2969 g1_policy()->phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0); 2970 2971 if (evacuation_failed()) { 2972 set_used(recalculate_used()); 2973 if (_archive_allocator != NULL) { 2974 _archive_allocator->clear_used(); 2975 } 2976 for (uint i = 0; i < ParallelGCThreads; i++) { 2977 if (_evacuation_failed_info_array[i].has_failed()) { 2978 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]); 2979 } 2980 } 2981 } else { 2982 // The "used" of the the collection set have already been subtracted 2983 // when they were freed. Add in the bytes evacuated. 2984 increase_used(g1_policy()->bytes_copied_during_gc()); 2985 } 2986 2987 if (collector_state()->in_initial_mark_gc()) { 2988 // We have to do this before we notify the CM threads that 2989 // they can start working to make sure that all the 2990 // appropriate initialization is done on the CM object. 2991 concurrent_mark()->post_initial_mark(); 2992 // Note that we don't actually trigger the CM thread at 2993 // this point. We do that later when we're sure that 2994 // the current thread has completed its logging output. 2995 } 2996 2997 allocate_dummy_regions(); 2998 2999 _allocator->init_mutator_alloc_region(); 3000 3001 { 3002 size_t expand_bytes = _heap_sizing_policy->expansion_amount(); 3003 if (expand_bytes > 0) { 3004 size_t bytes_before = capacity(); 3005 // No need for an ergo logging here, 3006 // expansion_amount() does this when it returns a value > 0. 3007 double expand_ms; 3008 if (!expand(expand_bytes, _workers, &expand_ms)) { 3009 // We failed to expand the heap. Cannot do anything about it. 3010 } 3011 g1_policy()->phase_times()->record_expand_heap_time(expand_ms); 3012 } 3013 } 3014 3015 // We redo the verification but now wrt to the new CSet which 3016 // has just got initialized after the previous CSet was freed. 3017 _cm->verify_no_cset_oops(); 3018 3019 // This timing is only used by the ergonomics to handle our pause target. 3020 // It is unclear why this should not include the full pause. We will 3021 // investigate this in CR 7178365. 3022 double sample_end_time_sec = os::elapsedTime(); 3023 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; 3024 size_t total_cards_scanned = g1_policy()->phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScanRSScannedCards); 3025 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc); 3026 3027 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before()); 3028 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc()); 3029 3030 if (VerifyRememberedSets) { 3031 log_info(gc, verify)("[Verifying RemSets after GC]"); 3032 VerifyRegionRemSetClosure v_cl; 3033 heap_region_iterate(&v_cl); 3034 } 3035 3036 _verifier->verify_after_gc(verify_type); 3037 _verifier->check_bitmaps("GC End"); 3038 3039 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition"); 3040 _ref_processor_stw->verify_no_references_recorded(); 3041 3042 // CM reference discovery will be re-enabled if necessary. 3043 } 3044 3045 #ifdef TRACESPINNING 3046 ParallelTaskTerminator::print_termination_counts(); 3047 #endif 3048 3049 gc_epilogue(false); 3050 } 3051 3052 // Print the remainder of the GC log output. 3053 if (evacuation_failed()) { 3054 log_info(gc)("To-space exhausted"); 3055 } 3056 3057 g1_policy()->print_phases(); 3058 heap_transition.print(); 3059 3060 // It is not yet to safe to tell the concurrent mark to 3061 // start as we have some optional output below. We don't want the 3062 // output from the concurrent mark thread interfering with this 3063 // logging output either. 3064 3065 _hrm.verify_optional(); 3066 _verifier->verify_region_sets_optional(); 3067 3068 TASKQUEUE_STATS_ONLY(print_taskqueue_stats()); 3069 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); 3070 3071 print_heap_after_gc(); 3072 print_heap_regions(); 3073 trace_heap_after_gc(_gc_tracer_stw); 3074 3075 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 3076 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 3077 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 3078 // before any GC notifications are raised. 3079 g1mm()->update_sizes(); 3080 3081 _gc_tracer_stw->report_evacuation_info(&evacuation_info); 3082 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold()); 3083 _gc_timer_stw->register_gc_end(); 3084 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions()); 3085 } 3086 // It should now be safe to tell the concurrent mark thread to start 3087 // without its logging output interfering with the logging output 3088 // that came from the pause. 3089 3090 if (should_start_conc_mark) { 3091 // CAUTION: after the doConcurrentMark() call below, 3092 // the concurrent marking thread(s) could be running 3093 // concurrently with us. Make sure that anything after 3094 // this point does not assume that we are the only GC thread 3095 // running. Note: of course, the actual marking work will 3096 // not start until the safepoint itself is released in 3097 // SuspendibleThreadSet::desynchronize(). 3098 do_concurrent_mark(); 3099 } 3100 3101 return true; 3102 } 3103 3104 void G1CollectedHeap::remove_self_forwarding_pointers() { 3105 G1ParRemoveSelfForwardPtrsTask rsfp_task; 3106 workers()->run_task(&rsfp_task); 3107 } 3108 3109 void G1CollectedHeap::restore_after_evac_failure() { 3110 double remove_self_forwards_start = os::elapsedTime(); 3111 3112 remove_self_forwarding_pointers(); 3113 SharedRestorePreservedMarksTaskExecutor task_executor(workers()); 3114 _preserved_marks_set.restore(&task_executor); 3115 3116 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0); 3117 } 3118 3119 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) { 3120 if (!_evacuation_failed) { 3121 _evacuation_failed = true; 3122 } 3123 3124 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size()); 3125 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m); 3126 } 3127 3128 bool G1ParEvacuateFollowersClosure::offer_termination() { 3129 G1ParScanThreadState* const pss = par_scan_state(); 3130 start_term_time(); 3131 const bool res = terminator()->offer_termination(); 3132 end_term_time(); 3133 return res; 3134 } 3135 3136 void G1ParEvacuateFollowersClosure::do_void() { 3137 G1ParScanThreadState* const pss = par_scan_state(); 3138 pss->trim_queue(); 3139 do { 3140 pss->steal_and_trim_queue(queues()); 3141 } while (!offer_termination()); 3142 } 3143 3144 class G1ParTask : public AbstractGangTask { 3145 protected: 3146 G1CollectedHeap* _g1h; 3147 G1ParScanThreadStateSet* _pss; 3148 RefToScanQueueSet* _queues; 3149 G1RootProcessor* _root_processor; 3150 ParallelTaskTerminator _terminator; 3151 uint _n_workers; 3152 3153 public: 3154 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers) 3155 : AbstractGangTask("G1 collection"), 3156 _g1h(g1h), 3157 _pss(per_thread_states), 3158 _queues(task_queues), 3159 _root_processor(root_processor), 3160 _terminator(n_workers, _queues), 3161 _n_workers(n_workers) 3162 {} 3163 3164 void work(uint worker_id) { 3165 if (worker_id >= _n_workers) return; // no work needed this round 3166 3167 double start_sec = os::elapsedTime(); 3168 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec); 3169 3170 { 3171 ResourceMark rm; 3172 HandleMark hm; 3173 3174 ReferenceProcessor* rp = _g1h->ref_processor_stw(); 3175 3176 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 3177 pss->set_ref_discoverer(rp); 3178 3179 double start_strong_roots_sec = os::elapsedTime(); 3180 3181 _root_processor->evacuate_roots(pss, worker_id); 3182 3183 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid 3184 // treating the nmethods visited to act as roots for concurrent marking. 3185 // We only want to make sure that the oops in the nmethods are adjusted with regard to the 3186 // objects copied by the current evacuation. 3187 _g1h->g1_rem_set()->oops_into_collection_set_do(pss, worker_id); 3188 3189 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec; 3190 3191 double term_sec = 0.0; 3192 size_t evac_term_attempts = 0; 3193 { 3194 double start = os::elapsedTime(); 3195 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator); 3196 evac.do_void(); 3197 3198 evac_term_attempts = evac.term_attempts(); 3199 term_sec = evac.term_time(); 3200 double elapsed_sec = os::elapsedTime() - start; 3201 3202 G1GCPhaseTimes* p = _g1h->g1_policy()->phase_times(); 3203 p->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec); 3204 p->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec); 3205 p->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts); 3206 } 3207 3208 assert(pss->queue_is_empty(), "should be empty"); 3209 3210 if (log_is_enabled(Debug, gc, task, stats)) { 3211 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); 3212 size_t lab_waste; 3213 size_t lab_undo_waste; 3214 pss->waste(lab_waste, lab_undo_waste); 3215 _g1h->print_termination_stats(worker_id, 3216 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */ 3217 strong_roots_sec * 1000.0, /* strong roots time */ 3218 term_sec * 1000.0, /* evac term time */ 3219 evac_term_attempts, /* evac term attempts */ 3220 lab_waste, /* alloc buffer waste */ 3221 lab_undo_waste /* undo waste */ 3222 ); 3223 } 3224 3225 // Close the inner scope so that the ResourceMark and HandleMark 3226 // destructors are executed here and are included as part of the 3227 // "GC Worker Time". 3228 } 3229 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime()); 3230 } 3231 }; 3232 3233 void G1CollectedHeap::print_termination_stats_hdr() { 3234 log_debug(gc, task, stats)("GC Termination Stats"); 3235 log_debug(gc, task, stats)(" elapsed --strong roots-- -------termination------- ------waste (KiB)------"); 3236 log_debug(gc, task, stats)("thr ms ms %% ms %% attempts total alloc undo"); 3237 log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------"); 3238 } 3239 3240 void G1CollectedHeap::print_termination_stats(uint worker_id, 3241 double elapsed_ms, 3242 double strong_roots_ms, 3243 double term_ms, 3244 size_t term_attempts, 3245 size_t alloc_buffer_waste, 3246 size_t undo_waste) const { 3247 log_debug(gc, task, stats) 3248 ("%3d %9.2f %9.2f %6.2f " 3249 "%9.2f %6.2f " SIZE_FORMAT_W(8) " " 3250 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7), 3251 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms, 3252 term_ms, term_ms * 100 / elapsed_ms, term_attempts, 3253 (alloc_buffer_waste + undo_waste) * HeapWordSize / K, 3254 alloc_buffer_waste * HeapWordSize / K, 3255 undo_waste * HeapWordSize / K); 3256 } 3257 3258 class G1StringCleaningTask : public AbstractGangTask { 3259 private: 3260 BoolObjectClosure* _is_alive; 3261 G1StringDedupUnlinkOrOopsDoClosure _dedup_closure; 3262 OopStorage::ParState<false /* concurrent */, false /* const */> _par_state_string; 3263 3264 int _initial_string_table_size; 3265 3266 bool _process_strings; 3267 int _strings_processed; 3268 int _strings_removed; 3269 3270 bool _process_string_dedup; 3271 3272 public: 3273 G1StringCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_string_dedup) : 3274 AbstractGangTask("String Unlinking"), 3275 _is_alive(is_alive), 3276 _dedup_closure(is_alive, NULL, false), 3277 _par_state_string(StringTable::weak_storage()), 3278 _process_strings(process_strings), _strings_processed(0), _strings_removed(0), 3279 _process_string_dedup(process_string_dedup) { 3280 3281 _initial_string_table_size = (int) StringTable::the_table()->table_size(); 3282 if (process_strings) { 3283 StringTable::reset_dead_counter(); 3284 } 3285 } 3286 3287 ~G1StringCleaningTask() { 3288 log_info(gc, stringtable)( 3289 "Cleaned string table, " 3290 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed", 3291 strings_processed(), strings_removed()); 3292 if (_process_strings) { 3293 StringTable::finish_dead_counter(); 3294 } 3295 } 3296 3297 void work(uint worker_id) { 3298 int strings_processed = 0; 3299 int strings_removed = 0; 3300 if (_process_strings) { 3301 StringTable::possibly_parallel_unlink(&_par_state_string, _is_alive, &strings_processed, &strings_removed); 3302 Atomic::add(strings_processed, &_strings_processed); 3303 Atomic::add(strings_removed, &_strings_removed); 3304 } 3305 if (_process_string_dedup) { 3306 G1StringDedup::parallel_unlink(&_dedup_closure, worker_id); 3307 } 3308 } 3309 3310 size_t strings_processed() const { return (size_t)_strings_processed; } 3311 size_t strings_removed() const { return (size_t)_strings_removed; } 3312 }; 3313 3314 class G1CodeCacheUnloadingTask { 3315 private: 3316 static Monitor* _lock; 3317 3318 BoolObjectClosure* const _is_alive; 3319 const bool _unloading_occurred; 3320 const uint _num_workers; 3321 3322 // Variables used to claim nmethods. 3323 CompiledMethod* _first_nmethod; 3324 CompiledMethod* volatile _claimed_nmethod; 3325 3326 // The list of nmethods that need to be processed by the second pass. 3327 CompiledMethod* volatile _postponed_list; 3328 volatile uint _num_entered_barrier; 3329 3330 public: 3331 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) : 3332 _is_alive(is_alive), 3333 _unloading_occurred(unloading_occurred), 3334 _num_workers(num_workers), 3335 _first_nmethod(NULL), 3336 _claimed_nmethod(NULL), 3337 _postponed_list(NULL), 3338 _num_entered_barrier(0) 3339 { 3340 CompiledMethod::increase_unloading_clock(); 3341 // Get first alive nmethod 3342 CompiledMethodIterator iter = CompiledMethodIterator(); 3343 if(iter.next_alive()) { 3344 _first_nmethod = iter.method(); 3345 } 3346 _claimed_nmethod = _first_nmethod; 3347 } 3348 3349 ~G1CodeCacheUnloadingTask() { 3350 CodeCache::verify_clean_inline_caches(); 3351 3352 CodeCache::set_needs_cache_clean(false); 3353 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be"); 3354 3355 CodeCache::verify_icholder_relocations(); 3356 } 3357 3358 private: 3359 void add_to_postponed_list(CompiledMethod* nm) { 3360 CompiledMethod* old; 3361 do { 3362 old = _postponed_list; 3363 nm->set_unloading_next(old); 3364 } while (Atomic::cmpxchg(nm, &_postponed_list, old) != old); 3365 } 3366 3367 void clean_nmethod(CompiledMethod* nm) { 3368 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred); 3369 3370 if (postponed) { 3371 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet. 3372 add_to_postponed_list(nm); 3373 } 3374 3375 // Mark that this nmethod has been cleaned/unloaded. 3376 // After this call, it will be safe to ask if this nmethod was unloaded or not. 3377 nm->set_unloading_clock(CompiledMethod::global_unloading_clock()); 3378 } 3379 3380 void clean_nmethod_postponed(CompiledMethod* nm) { 3381 nm->do_unloading_parallel_postponed(); 3382 } 3383 3384 static const int MaxClaimNmethods = 16; 3385 3386 void claim_nmethods(CompiledMethod** claimed_nmethods, int *num_claimed_nmethods) { 3387 CompiledMethod* first; 3388 CompiledMethodIterator last; 3389 3390 do { 3391 *num_claimed_nmethods = 0; 3392 3393 first = _claimed_nmethod; 3394 last = CompiledMethodIterator(first); 3395 3396 if (first != NULL) { 3397 3398 for (int i = 0; i < MaxClaimNmethods; i++) { 3399 if (!last.next_alive()) { 3400 break; 3401 } 3402 claimed_nmethods[i] = last.method(); 3403 (*num_claimed_nmethods)++; 3404 } 3405 } 3406 3407 } while (Atomic::cmpxchg(last.method(), &_claimed_nmethod, first) != first); 3408 } 3409 3410 CompiledMethod* claim_postponed_nmethod() { 3411 CompiledMethod* claim; 3412 CompiledMethod* next; 3413 3414 do { 3415 claim = _postponed_list; 3416 if (claim == NULL) { 3417 return NULL; 3418 } 3419 3420 next = claim->unloading_next(); 3421 3422 } while (Atomic::cmpxchg(next, &_postponed_list, claim) != claim); 3423 3424 return claim; 3425 } 3426 3427 public: 3428 // Mark that we're done with the first pass of nmethod cleaning. 3429 void barrier_mark(uint worker_id) { 3430 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 3431 _num_entered_barrier++; 3432 if (_num_entered_barrier == _num_workers) { 3433 ml.notify_all(); 3434 } 3435 } 3436 3437 // See if we have to wait for the other workers to 3438 // finish their first-pass nmethod cleaning work. 3439 void barrier_wait(uint worker_id) { 3440 if (_num_entered_barrier < _num_workers) { 3441 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 3442 while (_num_entered_barrier < _num_workers) { 3443 ml.wait(Mutex::_no_safepoint_check_flag, 0, false); 3444 } 3445 } 3446 } 3447 3448 // Cleaning and unloading of nmethods. Some work has to be postponed 3449 // to the second pass, when we know which nmethods survive. 3450 void work_first_pass(uint worker_id) { 3451 // The first nmethods is claimed by the first worker. 3452 if (worker_id == 0 && _first_nmethod != NULL) { 3453 clean_nmethod(_first_nmethod); 3454 _first_nmethod = NULL; 3455 } 3456 3457 int num_claimed_nmethods; 3458 CompiledMethod* claimed_nmethods[MaxClaimNmethods]; 3459 3460 while (true) { 3461 claim_nmethods(claimed_nmethods, &num_claimed_nmethods); 3462 3463 if (num_claimed_nmethods == 0) { 3464 break; 3465 } 3466 3467 for (int i = 0; i < num_claimed_nmethods; i++) { 3468 clean_nmethod(claimed_nmethods[i]); 3469 } 3470 } 3471 } 3472 3473 void work_second_pass(uint worker_id) { 3474 CompiledMethod* nm; 3475 // Take care of postponed nmethods. 3476 while ((nm = claim_postponed_nmethod()) != NULL) { 3477 clean_nmethod_postponed(nm); 3478 } 3479 } 3480 }; 3481 3482 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never); 3483 3484 class G1KlassCleaningTask : public StackObj { 3485 volatile int _clean_klass_tree_claimed; 3486 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator; 3487 3488 public: 3489 G1KlassCleaningTask() : 3490 _clean_klass_tree_claimed(0), 3491 _klass_iterator() { 3492 } 3493 3494 private: 3495 bool claim_clean_klass_tree_task() { 3496 if (_clean_klass_tree_claimed) { 3497 return false; 3498 } 3499 3500 return Atomic::cmpxchg(1, &_clean_klass_tree_claimed, 0) == 0; 3501 } 3502 3503 InstanceKlass* claim_next_klass() { 3504 Klass* klass; 3505 do { 3506 klass =_klass_iterator.next_klass(); 3507 } while (klass != NULL && !klass->is_instance_klass()); 3508 3509 // this can be null so don't call InstanceKlass::cast 3510 return static_cast<InstanceKlass*>(klass); 3511 } 3512 3513 public: 3514 3515 void clean_klass(InstanceKlass* ik) { 3516 ik->clean_weak_instanceklass_links(); 3517 } 3518 3519 void work() { 3520 ResourceMark rm; 3521 3522 // One worker will clean the subklass/sibling klass tree. 3523 if (claim_clean_klass_tree_task()) { 3524 Klass::clean_subklass_tree(); 3525 } 3526 3527 // All workers will help cleaning the classes, 3528 InstanceKlass* klass; 3529 while ((klass = claim_next_klass()) != NULL) { 3530 clean_klass(klass); 3531 } 3532 } 3533 }; 3534 3535 class G1ResolvedMethodCleaningTask : public StackObj { 3536 volatile int _resolved_method_task_claimed; 3537 public: 3538 G1ResolvedMethodCleaningTask() : 3539 _resolved_method_task_claimed(0) {} 3540 3541 bool claim_resolved_method_task() { 3542 if (_resolved_method_task_claimed) { 3543 return false; 3544 } 3545 return Atomic::cmpxchg(1, &_resolved_method_task_claimed, 0) == 0; 3546 } 3547 3548 // These aren't big, one thread can do it all. 3549 void work() { 3550 if (claim_resolved_method_task()) { 3551 ResolvedMethodTable::unlink(); 3552 } 3553 } 3554 }; 3555 3556 3557 // To minimize the remark pause times, the tasks below are done in parallel. 3558 class G1ParallelCleaningTask : public AbstractGangTask { 3559 private: 3560 bool _unloading_occurred; 3561 G1StringCleaningTask _string_task; 3562 G1CodeCacheUnloadingTask _code_cache_task; 3563 G1KlassCleaningTask _klass_cleaning_task; 3564 G1ResolvedMethodCleaningTask _resolved_method_cleaning_task; 3565 3566 public: 3567 // The constructor is run in the VMThread. 3568 G1ParallelCleaningTask(BoolObjectClosure* is_alive, uint num_workers, bool unloading_occurred) : 3569 AbstractGangTask("Parallel Cleaning"), 3570 _unloading_occurred(unloading_occurred), 3571 _string_task(is_alive, true, G1StringDedup::is_enabled()), 3572 _code_cache_task(num_workers, is_alive, unloading_occurred), 3573 _klass_cleaning_task(), 3574 _resolved_method_cleaning_task() { 3575 } 3576 3577 // The parallel work done by all worker threads. 3578 void work(uint worker_id) { 3579 // Do first pass of code cache cleaning. 3580 _code_cache_task.work_first_pass(worker_id); 3581 3582 // Let the threads mark that the first pass is done. 3583 _code_cache_task.barrier_mark(worker_id); 3584 3585 // Clean the Strings. 3586 _string_task.work(worker_id); 3587 3588 // Clean unreferenced things in the ResolvedMethodTable 3589 _resolved_method_cleaning_task.work(); 3590 3591 // Wait for all workers to finish the first code cache cleaning pass. 3592 _code_cache_task.barrier_wait(worker_id); 3593 3594 // Do the second code cache cleaning work, which realize on 3595 // the liveness information gathered during the first pass. 3596 _code_cache_task.work_second_pass(worker_id); 3597 3598 // Clean all klasses that were not unloaded. 3599 // The weak metadata in klass doesn't need to be 3600 // processed if there was no unloading. 3601 if (_unloading_occurred) { 3602 _klass_cleaning_task.work(); 3603 } 3604 } 3605 }; 3606 3607 3608 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive, 3609 bool class_unloading_occurred) { 3610 uint n_workers = workers()->active_workers(); 3611 3612 G1ParallelCleaningTask g1_unlink_task(is_alive, n_workers, class_unloading_occurred); 3613 workers()->run_task(&g1_unlink_task); 3614 } 3615 3616 void G1CollectedHeap::partial_cleaning(BoolObjectClosure* is_alive, 3617 bool process_strings, 3618 bool process_string_dedup) { 3619 if (!process_strings && !process_string_dedup) { 3620 // Nothing to clean. 3621 return; 3622 } 3623 3624 G1StringCleaningTask g1_unlink_task(is_alive, process_strings, process_string_dedup); 3625 workers()->run_task(&g1_unlink_task); 3626 } 3627 3628 class G1RedirtyLoggedCardsTask : public AbstractGangTask { 3629 private: 3630 DirtyCardQueueSet* _queue; 3631 G1CollectedHeap* _g1h; 3632 public: 3633 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"), 3634 _queue(queue), _g1h(g1h) { } 3635 3636 virtual void work(uint worker_id) { 3637 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times(); 3638 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id); 3639 3640 RedirtyLoggedCardTableEntryClosure cl(_g1h); 3641 _queue->par_apply_closure_to_all_completed_buffers(&cl); 3642 3643 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied()); 3644 } 3645 }; 3646 3647 void G1CollectedHeap::redirty_logged_cards() { 3648 double redirty_logged_cards_start = os::elapsedTime(); 3649 3650 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this); 3651 dirty_card_queue_set().reset_for_par_iteration(); 3652 workers()->run_task(&redirty_task); 3653 3654 DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set(); 3655 dcq.merge_bufferlists(&dirty_card_queue_set()); 3656 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed"); 3657 3658 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0); 3659 } 3660 3661 // Weak Reference Processing support 3662 3663 bool G1STWIsAliveClosure::do_object_b(oop p) { 3664 // An object is reachable if it is outside the collection set, 3665 // or is inside and copied. 3666 return !_g1h->is_in_cset(p) || p->is_forwarded(); 3667 } 3668 3669 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) { 3670 assert(obj != NULL, "must not be NULL"); 3671 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj)); 3672 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below 3673 // may falsely indicate that this is not the case here: however the collection set only 3674 // contains old regions when concurrent mark is not running. 3675 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor(); 3676 } 3677 3678 // Non Copying Keep Alive closure 3679 class G1KeepAliveClosure: public OopClosure { 3680 G1CollectedHeap*_g1h; 3681 public: 3682 G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {} 3683 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } 3684 void do_oop(oop* p) { 3685 oop obj = *p; 3686 assert(obj != NULL, "the caller should have filtered out NULL values"); 3687 3688 const InCSetState cset_state =_g1h->in_cset_state(obj); 3689 if (!cset_state.is_in_cset_or_humongous()) { 3690 return; 3691 } 3692 if (cset_state.is_in_cset()) { 3693 assert( obj->is_forwarded(), "invariant" ); 3694 *p = obj->forwardee(); 3695 } else { 3696 assert(!obj->is_forwarded(), "invariant" ); 3697 assert(cset_state.is_humongous(), 3698 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value()); 3699 _g1h->set_humongous_is_live(obj); 3700 } 3701 } 3702 }; 3703 3704 // Copying Keep Alive closure - can be called from both 3705 // serial and parallel code as long as different worker 3706 // threads utilize different G1ParScanThreadState instances 3707 // and different queues. 3708 3709 class G1CopyingKeepAliveClosure: public OopClosure { 3710 G1CollectedHeap* _g1h; 3711 G1ParScanThreadState* _par_scan_state; 3712 3713 public: 3714 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, 3715 G1ParScanThreadState* pss): 3716 _g1h(g1h), 3717 _par_scan_state(pss) 3718 {} 3719 3720 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 3721 virtual void do_oop( oop* p) { do_oop_work(p); } 3722 3723 template <class T> void do_oop_work(T* p) { 3724 oop obj = RawAccess<>::oop_load(p); 3725 3726 if (_g1h->is_in_cset_or_humongous(obj)) { 3727 // If the referent object has been forwarded (either copied 3728 // to a new location or to itself in the event of an 3729 // evacuation failure) then we need to update the reference 3730 // field and, if both reference and referent are in the G1 3731 // heap, update the RSet for the referent. 3732 // 3733 // If the referent has not been forwarded then we have to keep 3734 // it alive by policy. Therefore we have copy the referent. 3735 // 3736 // When the queue is drained (after each phase of reference processing) 3737 // the object and it's followers will be copied, the reference field set 3738 // to point to the new location, and the RSet updated. 3739 _par_scan_state->push_on_queue(p); 3740 } 3741 } 3742 }; 3743 3744 // Serial drain queue closure. Called as the 'complete_gc' 3745 // closure for each discovered list in some of the 3746 // reference processing phases. 3747 3748 class G1STWDrainQueueClosure: public VoidClosure { 3749 protected: 3750 G1CollectedHeap* _g1h; 3751 G1ParScanThreadState* _par_scan_state; 3752 3753 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 3754 3755 public: 3756 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : 3757 _g1h(g1h), 3758 _par_scan_state(pss) 3759 { } 3760 3761 void do_void() { 3762 G1ParScanThreadState* const pss = par_scan_state(); 3763 pss->trim_queue(); 3764 } 3765 }; 3766 3767 // Parallel Reference Processing closures 3768 3769 // Implementation of AbstractRefProcTaskExecutor for parallel reference 3770 // processing during G1 evacuation pauses. 3771 3772 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 3773 private: 3774 G1CollectedHeap* _g1h; 3775 G1ParScanThreadStateSet* _pss; 3776 RefToScanQueueSet* _queues; 3777 WorkGang* _workers; 3778 3779 public: 3780 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, 3781 G1ParScanThreadStateSet* per_thread_states, 3782 WorkGang* workers, 3783 RefToScanQueueSet *task_queues) : 3784 _g1h(g1h), 3785 _pss(per_thread_states), 3786 _queues(task_queues), 3787 _workers(workers) 3788 { 3789 g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers()); 3790 } 3791 3792 // Executes the given task using concurrent marking worker threads. 3793 virtual void execute(ProcessTask& task, uint ergo_workers); 3794 }; 3795 3796 // Gang task for possibly parallel reference processing 3797 3798 class G1STWRefProcTaskProxy: public AbstractGangTask { 3799 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 3800 ProcessTask& _proc_task; 3801 G1CollectedHeap* _g1h; 3802 G1ParScanThreadStateSet* _pss; 3803 RefToScanQueueSet* _task_queues; 3804 ParallelTaskTerminator* _terminator; 3805 3806 public: 3807 G1STWRefProcTaskProxy(ProcessTask& proc_task, 3808 G1CollectedHeap* g1h, 3809 G1ParScanThreadStateSet* per_thread_states, 3810 RefToScanQueueSet *task_queues, 3811 ParallelTaskTerminator* terminator) : 3812 AbstractGangTask("Process reference objects in parallel"), 3813 _proc_task(proc_task), 3814 _g1h(g1h), 3815 _pss(per_thread_states), 3816 _task_queues(task_queues), 3817 _terminator(terminator) 3818 {} 3819 3820 virtual void work(uint worker_id) { 3821 // The reference processing task executed by a single worker. 3822 ResourceMark rm; 3823 HandleMark hm; 3824 3825 G1STWIsAliveClosure is_alive(_g1h); 3826 3827 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 3828 pss->set_ref_discoverer(NULL); 3829 3830 // Keep alive closure. 3831 G1CopyingKeepAliveClosure keep_alive(_g1h, pss); 3832 3833 // Complete GC closure 3834 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator); 3835 3836 // Call the reference processing task's work routine. 3837 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); 3838 3839 // Note we cannot assert that the refs array is empty here as not all 3840 // of the processing tasks (specifically phase2 - pp2_work) execute 3841 // the complete_gc closure (which ordinarily would drain the queue) so 3842 // the queue may not be empty. 3843 } 3844 }; 3845 3846 // Driver routine for parallel reference processing. 3847 // Creates an instance of the ref processing gang 3848 // task and has the worker threads execute it. 3849 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) { 3850 assert(_workers != NULL, "Need parallel worker threads."); 3851 3852 assert(_workers->active_workers() >= ergo_workers, 3853 "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)", 3854 ergo_workers, _workers->active_workers()); 3855 ParallelTaskTerminator terminator(ergo_workers, _queues); 3856 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator); 3857 3858 _workers->run_task(&proc_task_proxy, ergo_workers); 3859 } 3860 3861 // End of weak reference support closures 3862 3863 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) { 3864 double ref_proc_start = os::elapsedTime(); 3865 3866 ReferenceProcessor* rp = _ref_processor_stw; 3867 assert(rp->discovery_enabled(), "should have been enabled"); 3868 3869 // Closure to test whether a referent is alive. 3870 G1STWIsAliveClosure is_alive(this); 3871 3872 // Even when parallel reference processing is enabled, the processing 3873 // of JNI refs is serial and performed serially by the current thread 3874 // rather than by a worker. The following PSS will be used for processing 3875 // JNI refs. 3876 3877 // Use only a single queue for this PSS. 3878 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0); 3879 pss->set_ref_discoverer(NULL); 3880 assert(pss->queue_is_empty(), "pre-condition"); 3881 3882 // Keep alive closure. 3883 G1CopyingKeepAliveClosure keep_alive(this, pss); 3884 3885 // Serial Complete GC closure 3886 G1STWDrainQueueClosure drain_queue(this, pss); 3887 3888 // Setup the soft refs policy... 3889 rp->setup_policy(false); 3890 3891 ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times(); 3892 3893 ReferenceProcessorStats stats; 3894 if (!rp->processing_is_mt()) { 3895 // Serial reference processing... 3896 stats = rp->process_discovered_references(&is_alive, 3897 &keep_alive, 3898 &drain_queue, 3899 NULL, 3900 pt); 3901 } else { 3902 uint no_of_gc_workers = workers()->active_workers(); 3903 3904 // Parallel reference processing 3905 assert(no_of_gc_workers <= rp->max_num_queues(), 3906 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u", 3907 no_of_gc_workers, rp->max_num_queues()); 3908 3909 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues); 3910 stats = rp->process_discovered_references(&is_alive, 3911 &keep_alive, 3912 &drain_queue, 3913 &par_task_executor, 3914 pt); 3915 } 3916 3917 _gc_tracer_stw->report_gc_reference_stats(stats); 3918 3919 // We have completed copying any necessary live referent objects. 3920 assert(pss->queue_is_empty(), "both queue and overflow should be empty"); 3921 3922 make_pending_list_reachable(); 3923 3924 rp->verify_no_references_recorded(); 3925 3926 double ref_proc_time = os::elapsedTime() - ref_proc_start; 3927 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 3928 } 3929 3930 void G1CollectedHeap::make_pending_list_reachable() { 3931 if (collector_state()->in_initial_mark_gc()) { 3932 oop pll_head = Universe::reference_pending_list(); 3933 if (pll_head != NULL) { 3934 // Any valid worker id is fine here as we are in the VM thread and single-threaded. 3935 _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head); 3936 } 3937 } 3938 } 3939 3940 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) { 3941 double merge_pss_time_start = os::elapsedTime(); 3942 per_thread_states->flush(); 3943 g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0); 3944 } 3945 3946 void G1CollectedHeap::pre_evacuate_collection_set() { 3947 _expand_heap_after_alloc_failure = true; 3948 _evacuation_failed = false; 3949 3950 // Disable the hot card cache. 3951 _hot_card_cache->reset_hot_cache_claimed_index(); 3952 _hot_card_cache->set_use_cache(false); 3953 3954 g1_rem_set()->prepare_for_oops_into_collection_set_do(); 3955 _preserved_marks_set.assert_empty(); 3956 3957 G1GCPhaseTimes* phase_times = g1_policy()->phase_times(); 3958 3959 // InitialMark needs claim bits to keep track of the marked-through CLDs. 3960 if (collector_state()->in_initial_mark_gc()) { 3961 double start_clear_claimed_marks = os::elapsedTime(); 3962 3963 ClassLoaderDataGraph::clear_claimed_marks(); 3964 3965 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0; 3966 phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms); 3967 } 3968 } 3969 3970 void G1CollectedHeap::evacuate_collection_set(G1ParScanThreadStateSet* per_thread_states) { 3971 // Should G1EvacuationFailureALot be in effect for this GC? 3972 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) 3973 3974 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty"); 3975 3976 G1GCPhaseTimes* phase_times = g1_policy()->phase_times(); 3977 3978 double start_par_time_sec = os::elapsedTime(); 3979 double end_par_time_sec; 3980 3981 { 3982 const uint n_workers = workers()->active_workers(); 3983 G1RootProcessor root_processor(this, n_workers); 3984 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers); 3985 3986 print_termination_stats_hdr(); 3987 3988 workers()->run_task(&g1_par_task); 3989 end_par_time_sec = os::elapsedTime(); 3990 3991 // Closing the inner scope will execute the destructor 3992 // for the G1RootProcessor object. We record the current 3993 // elapsed time before closing the scope so that time 3994 // taken for the destructor is NOT included in the 3995 // reported parallel time. 3996 } 3997 3998 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0; 3999 phase_times->record_par_time(par_time_ms); 4000 4001 double code_root_fixup_time_ms = 4002 (os::elapsedTime() - end_par_time_sec) * 1000.0; 4003 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms); 4004 } 4005 4006 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) { 4007 // Also cleans the card table from temporary duplicate detection information used 4008 // during UpdateRS/ScanRS. 4009 g1_rem_set()->cleanup_after_oops_into_collection_set_do(); 4010 4011 // Process any discovered reference objects - we have 4012 // to do this _before_ we retire the GC alloc regions 4013 // as we may have to copy some 'reachable' referent 4014 // objects (and their reachable sub-graphs) that were 4015 // not copied during the pause. 4016 process_discovered_references(per_thread_states); 4017 4018 // FIXME 4019 // CM's reference processing also cleans up the string table. 4020 // Should we do that here also? We could, but it is a serial operation 4021 // and could significantly increase the pause time. 4022 4023 G1STWIsAliveClosure is_alive(this); 4024 G1KeepAliveClosure keep_alive(this); 4025 4026 { 4027 double start = os::elapsedTime(); 4028 4029 WeakProcessor::weak_oops_do(&is_alive, &keep_alive); 4030 4031 double time_ms = (os::elapsedTime() - start) * 1000.0; 4032 g1_policy()->phase_times()->record_weak_ref_proc_time(time_ms); 4033 } 4034 4035 if (G1StringDedup::is_enabled()) { 4036 double fixup_start = os::elapsedTime(); 4037 4038 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times()); 4039 4040 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0; 4041 g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms); 4042 } 4043 4044 if (evacuation_failed()) { 4045 restore_after_evac_failure(); 4046 4047 // Reset the G1EvacuationFailureALot counters and flags 4048 // Note: the values are reset only when an actual 4049 // evacuation failure occurs. 4050 NOT_PRODUCT(reset_evacuation_should_fail();) 4051 } 4052 4053 _preserved_marks_set.assert_empty(); 4054 4055 _allocator->release_gc_alloc_regions(evacuation_info); 4056 4057 merge_per_thread_state_info(per_thread_states); 4058 4059 // Reset and re-enable the hot card cache. 4060 // Note the counts for the cards in the regions in the 4061 // collection set are reset when the collection set is freed. 4062 _hot_card_cache->reset_hot_cache(); 4063 _hot_card_cache->set_use_cache(true); 4064 4065 purge_code_root_memory(); 4066 4067 redirty_logged_cards(); 4068 #if COMPILER2_OR_JVMCI 4069 double start = os::elapsedTime(); 4070 DerivedPointerTable::update_pointers(); 4071 g1_policy()->phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0); 4072 #endif 4073 g1_policy()->print_age_table(); 4074 } 4075 4076 void G1CollectedHeap::record_obj_copy_mem_stats() { 4077 g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize); 4078 4079 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats), 4080 create_g1_evac_summary(&_old_evac_stats)); 4081 } 4082 4083 void G1CollectedHeap::free_region(HeapRegion* hr, 4084 FreeRegionList* free_list, 4085 bool skip_remset, 4086 bool skip_hot_card_cache, 4087 bool locked) { 4088 assert(!hr->is_free(), "the region should not be free"); 4089 assert(!hr->is_empty(), "the region should not be empty"); 4090 assert(_hrm.is_available(hr->hrm_index()), "region should be committed"); 4091 assert(free_list != NULL, "pre-condition"); 4092 4093 if (G1VerifyBitmaps) { 4094 MemRegion mr(hr->bottom(), hr->end()); 4095 concurrent_mark()->clear_range_in_prev_bitmap(mr); 4096 } 4097 4098 // Clear the card counts for this region. 4099 // Note: we only need to do this if the region is not young 4100 // (since we don't refine cards in young regions). 4101 if (!skip_hot_card_cache && !hr->is_young()) { 4102 _hot_card_cache->reset_card_counts(hr); 4103 } 4104 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */); 4105 _g1_policy->remset_tracker()->update_at_free(hr); 4106 free_list->add_ordered(hr); 4107 } 4108 4109 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 4110 FreeRegionList* free_list) { 4111 assert(hr->is_humongous(), "this is only for humongous regions"); 4112 assert(free_list != NULL, "pre-condition"); 4113 hr->clear_humongous(); 4114 free_region(hr, free_list, false /* skip_remset */, false /* skip_hcc */, true /* locked */); 4115 } 4116 4117 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed, 4118 const uint humongous_regions_removed) { 4119 if (old_regions_removed > 0 || humongous_regions_removed > 0) { 4120 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 4121 _old_set.bulk_remove(old_regions_removed); 4122 _humongous_set.bulk_remove(humongous_regions_removed); 4123 } 4124 4125 } 4126 4127 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) { 4128 assert(list != NULL, "list can't be null"); 4129 if (!list->is_empty()) { 4130 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag); 4131 _hrm.insert_list_into_free_list(list); 4132 } 4133 } 4134 4135 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) { 4136 decrease_used(bytes); 4137 } 4138 4139 class G1FreeCollectionSetTask : public AbstractGangTask { 4140 private: 4141 4142 // Closure applied to all regions in the collection set to do work that needs to 4143 // be done serially in a single thread. 4144 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure { 4145 private: 4146 EvacuationInfo* _evacuation_info; 4147 const size_t* _surviving_young_words; 4148 4149 // Bytes used in successfully evacuated regions before the evacuation. 4150 size_t _before_used_bytes; 4151 // Bytes used in unsucessfully evacuated regions before the evacuation 4152 size_t _after_used_bytes; 4153 4154 size_t _bytes_allocated_in_old_since_last_gc; 4155 4156 size_t _failure_used_words; 4157 size_t _failure_waste_words; 4158 4159 FreeRegionList _local_free_list; 4160 public: 4161 G1SerialFreeCollectionSetClosure(EvacuationInfo* evacuation_info, const size_t* surviving_young_words) : 4162 HeapRegionClosure(), 4163 _evacuation_info(evacuation_info), 4164 _surviving_young_words(surviving_young_words), 4165 _before_used_bytes(0), 4166 _after_used_bytes(0), 4167 _bytes_allocated_in_old_since_last_gc(0), 4168 _failure_used_words(0), 4169 _failure_waste_words(0), 4170 _local_free_list("Local Region List for CSet Freeing") { 4171 } 4172 4173 virtual bool do_heap_region(HeapRegion* r) { 4174 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4175 4176 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index()); 4177 g1h->clear_in_cset(r); 4178 4179 if (r->is_young()) { 4180 assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(), 4181 "Young index %d is wrong for region %u of type %s with %u young regions", 4182 r->young_index_in_cset(), 4183 r->hrm_index(), 4184 r->get_type_str(), 4185 g1h->collection_set()->young_region_length()); 4186 size_t words_survived = _surviving_young_words[r->young_index_in_cset()]; 4187 r->record_surv_words_in_group(words_survived); 4188 } 4189 4190 if (!r->evacuation_failed()) { 4191 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index()); 4192 _before_used_bytes += r->used(); 4193 g1h->free_region(r, 4194 &_local_free_list, 4195 true, /* skip_remset */ 4196 true, /* skip_hot_card_cache */ 4197 true /* locked */); 4198 } else { 4199 r->uninstall_surv_rate_group(); 4200 r->set_young_index_in_cset(-1); 4201 r->set_evacuation_failed(false); 4202 // When moving a young gen region to old gen, we "allocate" that whole region 4203 // there. This is in addition to any already evacuated objects. Notify the 4204 // policy about that. 4205 // Old gen regions do not cause an additional allocation: both the objects 4206 // still in the region and the ones already moved are accounted for elsewhere. 4207 if (r->is_young()) { 4208 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes; 4209 } 4210 // The region is now considered to be old. 4211 r->set_old(); 4212 // Do some allocation statistics accounting. Regions that failed evacuation 4213 // are always made old, so there is no need to update anything in the young 4214 // gen statistics, but we need to update old gen statistics. 4215 size_t used_words = r->marked_bytes() / HeapWordSize; 4216 4217 _failure_used_words += used_words; 4218 _failure_waste_words += HeapRegion::GrainWords - used_words; 4219 4220 g1h->old_set_add(r); 4221 _after_used_bytes += r->used(); 4222 } 4223 return false; 4224 } 4225 4226 void complete_work() { 4227 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4228 4229 _evacuation_info->set_regions_freed(_local_free_list.length()); 4230 _evacuation_info->increment_collectionset_used_after(_after_used_bytes); 4231 4232 g1h->prepend_to_freelist(&_local_free_list); 4233 g1h->decrement_summary_bytes(_before_used_bytes); 4234 4235 G1Policy* policy = g1h->g1_policy(); 4236 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc); 4237 4238 g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words); 4239 } 4240 }; 4241 4242 G1CollectionSet* _collection_set; 4243 G1SerialFreeCollectionSetClosure _cl; 4244 const size_t* _surviving_young_words; 4245 4246 size_t _rs_lengths; 4247 4248 volatile jint _serial_work_claim; 4249 4250 struct WorkItem { 4251 uint region_idx; 4252 bool is_young; 4253 bool evacuation_failed; 4254 4255 WorkItem(HeapRegion* r) { 4256 region_idx = r->hrm_index(); 4257 is_young = r->is_young(); 4258 evacuation_failed = r->evacuation_failed(); 4259 } 4260 }; 4261 4262 volatile size_t _parallel_work_claim; 4263 size_t _num_work_items; 4264 WorkItem* _work_items; 4265 4266 void do_serial_work() { 4267 // Need to grab the lock to be allowed to modify the old region list. 4268 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 4269 _collection_set->iterate(&_cl); 4270 } 4271 4272 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) { 4273 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4274 4275 HeapRegion* r = g1h->region_at(region_idx); 4276 assert(!g1h->is_on_master_free_list(r), "sanity"); 4277 4278 Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths); 4279 4280 if (!is_young) { 4281 g1h->_hot_card_cache->reset_card_counts(r); 4282 } 4283 4284 if (!evacuation_failed) { 4285 r->rem_set()->clear_locked(); 4286 } 4287 } 4288 4289 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure { 4290 private: 4291 size_t _cur_idx; 4292 WorkItem* _work_items; 4293 public: 4294 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { } 4295 4296 virtual bool do_heap_region(HeapRegion* r) { 4297 _work_items[_cur_idx++] = WorkItem(r); 4298 return false; 4299 } 4300 }; 4301 4302 void prepare_work() { 4303 G1PrepareFreeCollectionSetClosure cl(_work_items); 4304 _collection_set->iterate(&cl); 4305 } 4306 4307 void complete_work() { 4308 _cl.complete_work(); 4309 4310 G1Policy* policy = G1CollectedHeap::heap()->g1_policy(); 4311 policy->record_max_rs_lengths(_rs_lengths); 4312 policy->cset_regions_freed(); 4313 } 4314 public: 4315 G1FreeCollectionSetTask(G1CollectionSet* collection_set, EvacuationInfo* evacuation_info, const size_t* surviving_young_words) : 4316 AbstractGangTask("G1 Free Collection Set"), 4317 _collection_set(collection_set), 4318 _cl(evacuation_info, surviving_young_words), 4319 _surviving_young_words(surviving_young_words), 4320 _rs_lengths(0), 4321 _serial_work_claim(0), 4322 _parallel_work_claim(0), 4323 _num_work_items(collection_set->region_length()), 4324 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) { 4325 prepare_work(); 4326 } 4327 4328 ~G1FreeCollectionSetTask() { 4329 complete_work(); 4330 FREE_C_HEAP_ARRAY(WorkItem, _work_items); 4331 } 4332 4333 // Chunk size for work distribution. The chosen value has been determined experimentally 4334 // to be a good tradeoff between overhead and achievable parallelism. 4335 static uint chunk_size() { return 32; } 4336 4337 virtual void work(uint worker_id) { 4338 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times(); 4339 4340 // Claim serial work. 4341 if (_serial_work_claim == 0) { 4342 jint value = Atomic::add(1, &_serial_work_claim) - 1; 4343 if (value == 0) { 4344 double serial_time = os::elapsedTime(); 4345 do_serial_work(); 4346 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0); 4347 } 4348 } 4349 4350 // Start parallel work. 4351 double young_time = 0.0; 4352 bool has_young_time = false; 4353 double non_young_time = 0.0; 4354 bool has_non_young_time = false; 4355 4356 while (true) { 4357 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim); 4358 size_t cur = end - chunk_size(); 4359 4360 if (cur >= _num_work_items) { 4361 break; 4362 } 4363 4364 double start_time = os::elapsedTime(); 4365 4366 end = MIN2(end, _num_work_items); 4367 4368 for (; cur < end; cur++) { 4369 bool is_young = _work_items[cur].is_young; 4370 4371 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed); 4372 4373 double end_time = os::elapsedTime(); 4374 double time_taken = end_time - start_time; 4375 if (is_young) { 4376 young_time += time_taken; 4377 has_young_time = true; 4378 } else { 4379 non_young_time += time_taken; 4380 has_non_young_time = true; 4381 } 4382 start_time = end_time; 4383 } 4384 } 4385 4386 if (has_young_time) { 4387 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time); 4388 } 4389 if (has_non_young_time) { 4390 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time); 4391 } 4392 } 4393 }; 4394 4395 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) { 4396 _eden.clear(); 4397 4398 double free_cset_start_time = os::elapsedTime(); 4399 4400 { 4401 uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U); 4402 uint const num_workers = MIN2(workers()->active_workers(), num_chunks); 4403 4404 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words); 4405 4406 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u", 4407 cl.name(), 4408 num_workers, 4409 _collection_set.region_length()); 4410 workers()->run_task(&cl, num_workers); 4411 } 4412 g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0); 4413 4414 collection_set->clear(); 4415 } 4416 4417 class G1FreeHumongousRegionClosure : public HeapRegionClosure { 4418 private: 4419 FreeRegionList* _free_region_list; 4420 HeapRegionSet* _proxy_set; 4421 uint _humongous_objects_reclaimed; 4422 uint _humongous_regions_reclaimed; 4423 size_t _freed_bytes; 4424 public: 4425 4426 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) : 4427 _free_region_list(free_region_list), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) { 4428 } 4429 4430 virtual bool do_heap_region(HeapRegion* r) { 4431 if (!r->is_starts_humongous()) { 4432 return false; 4433 } 4434 4435 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4436 4437 oop obj = (oop)r->bottom(); 4438 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap(); 4439 4440 // The following checks whether the humongous object is live are sufficient. 4441 // The main additional check (in addition to having a reference from the roots 4442 // or the young gen) is whether the humongous object has a remembered set entry. 4443 // 4444 // A humongous object cannot be live if there is no remembered set for it 4445 // because: 4446 // - there can be no references from within humongous starts regions referencing 4447 // the object because we never allocate other objects into them. 4448 // (I.e. there are no intra-region references that may be missed by the 4449 // remembered set) 4450 // - as soon there is a remembered set entry to the humongous starts region 4451 // (i.e. it has "escaped" to an old object) this remembered set entry will stay 4452 // until the end of a concurrent mark. 4453 // 4454 // It is not required to check whether the object has been found dead by marking 4455 // or not, in fact it would prevent reclamation within a concurrent cycle, as 4456 // all objects allocated during that time are considered live. 4457 // SATB marking is even more conservative than the remembered set. 4458 // So if at this point in the collection there is no remembered set entry, 4459 // nobody has a reference to it. 4460 // At the start of collection we flush all refinement logs, and remembered sets 4461 // are completely up-to-date wrt to references to the humongous object. 4462 // 4463 // Other implementation considerations: 4464 // - never consider object arrays at this time because they would pose 4465 // considerable effort for cleaning up the the remembered sets. This is 4466 // required because stale remembered sets might reference locations that 4467 // are currently allocated into. 4468 uint region_idx = r->hrm_index(); 4469 if (!g1h->is_humongous_reclaim_candidate(region_idx) || 4470 !r->rem_set()->is_empty()) { 4471 log_debug(gc, humongous)("Live humongous region %u object size " SIZE_FORMAT " start " PTR_FORMAT " with remset " SIZE_FORMAT " code roots " SIZE_FORMAT " is marked %d reclaim candidate %d type array %d", 4472 region_idx, 4473 (size_t)obj->size() * HeapWordSize, 4474 p2i(r->bottom()), 4475 r->rem_set()->occupied(), 4476 r->rem_set()->strong_code_roots_list_length(), 4477 next_bitmap->is_marked(r->bottom()), 4478 g1h->is_humongous_reclaim_candidate(region_idx), 4479 obj->is_typeArray() 4480 ); 4481 return false; 4482 } 4483 4484 guarantee(obj->is_typeArray(), 4485 "Only eagerly reclaiming type arrays is supported, but the object " 4486 PTR_FORMAT " is not.", p2i(r->bottom())); 4487 4488 log_debug(gc, humongous)("Dead humongous region %u object size " SIZE_FORMAT " start " PTR_FORMAT " with remset " SIZE_FORMAT " code roots " SIZE_FORMAT " is marked %d reclaim candidate %d type array %d", 4489 region_idx, 4490 (size_t)obj->size() * HeapWordSize, 4491 p2i(r->bottom()), 4492 r->rem_set()->occupied(), 4493 r->rem_set()->strong_code_roots_list_length(), 4494 next_bitmap->is_marked(r->bottom()), 4495 g1h->is_humongous_reclaim_candidate(region_idx), 4496 obj->is_typeArray() 4497 ); 4498 4499 G1ConcurrentMark* const cm = g1h->concurrent_mark(); 4500 cm->humongous_object_eagerly_reclaimed(r); 4501 assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj), 4502 "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s", 4503 region_idx, 4504 BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)), 4505 BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj))); 4506 _humongous_objects_reclaimed++; 4507 do { 4508 HeapRegion* next = g1h->next_region_in_humongous(r); 4509 _freed_bytes += r->used(); 4510 r->set_containing_set(NULL); 4511 _humongous_regions_reclaimed++; 4512 g1h->free_humongous_region(r, _free_region_list); 4513 r = next; 4514 } while (r != NULL); 4515 4516 return false; 4517 } 4518 4519 uint humongous_objects_reclaimed() { 4520 return _humongous_objects_reclaimed; 4521 } 4522 4523 uint humongous_regions_reclaimed() { 4524 return _humongous_regions_reclaimed; 4525 } 4526 4527 size_t bytes_freed() const { 4528 return _freed_bytes; 4529 } 4530 }; 4531 4532 void G1CollectedHeap::eagerly_reclaim_humongous_regions() { 4533 assert_at_safepoint_on_vm_thread(); 4534 4535 if (!G1EagerReclaimHumongousObjects || 4536 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) { 4537 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0); 4538 return; 4539 } 4540 4541 double start_time = os::elapsedTime(); 4542 4543 FreeRegionList local_cleanup_list("Local Humongous Cleanup List"); 4544 4545 G1FreeHumongousRegionClosure cl(&local_cleanup_list); 4546 heap_region_iterate(&cl); 4547 4548 remove_from_old_sets(0, cl.humongous_regions_reclaimed()); 4549 4550 G1HRPrinter* hrp = hr_printer(); 4551 if (hrp->is_active()) { 4552 FreeRegionListIterator iter(&local_cleanup_list); 4553 while (iter.more_available()) { 4554 HeapRegion* hr = iter.get_next(); 4555 hrp->cleanup(hr); 4556 } 4557 } 4558 4559 prepend_to_freelist(&local_cleanup_list); 4560 decrement_summary_bytes(cl.bytes_freed()); 4561 4562 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0, 4563 cl.humongous_objects_reclaimed()); 4564 } 4565 4566 class G1AbandonCollectionSetClosure : public HeapRegionClosure { 4567 public: 4568 virtual bool do_heap_region(HeapRegion* r) { 4569 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index()); 4570 G1CollectedHeap::heap()->clear_in_cset(r); 4571 r->set_young_index_in_cset(-1); 4572 return false; 4573 } 4574 }; 4575 4576 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) { 4577 G1AbandonCollectionSetClosure cl; 4578 collection_set->iterate(&cl); 4579 4580 collection_set->clear(); 4581 collection_set->stop_incremental_building(); 4582 } 4583 4584 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) { 4585 return _allocator->is_retained_old_region(hr); 4586 } 4587 4588 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 4589 _eden.add(hr); 4590 _g1_policy->set_region_eden(hr); 4591 } 4592 4593 #ifdef ASSERT 4594 4595 class NoYoungRegionsClosure: public HeapRegionClosure { 4596 private: 4597 bool _success; 4598 public: 4599 NoYoungRegionsClosure() : _success(true) { } 4600 bool do_heap_region(HeapRegion* r) { 4601 if (r->is_young()) { 4602 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young", 4603 p2i(r->bottom()), p2i(r->end())); 4604 _success = false; 4605 } 4606 return false; 4607 } 4608 bool success() { return _success; } 4609 }; 4610 4611 bool G1CollectedHeap::check_young_list_empty() { 4612 bool ret = (young_regions_count() == 0); 4613 4614 NoYoungRegionsClosure closure; 4615 heap_region_iterate(&closure); 4616 ret = ret && closure.success(); 4617 4618 return ret; 4619 } 4620 4621 #endif // ASSERT 4622 4623 class TearDownRegionSetsClosure : public HeapRegionClosure { 4624 private: 4625 HeapRegionSet *_old_set; 4626 4627 public: 4628 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { } 4629 4630 bool do_heap_region(HeapRegion* r) { 4631 if (r->is_old()) { 4632 _old_set->remove(r); 4633 } else if(r->is_young()) { 4634 r->uninstall_surv_rate_group(); 4635 } else { 4636 // We ignore free regions, we'll empty the free list afterwards. 4637 // We ignore humongous regions, we're not tearing down the 4638 // humongous regions set. 4639 assert(r->is_free() || r->is_humongous(), 4640 "it cannot be another type"); 4641 } 4642 return false; 4643 } 4644 4645 ~TearDownRegionSetsClosure() { 4646 assert(_old_set->is_empty(), "post-condition"); 4647 } 4648 }; 4649 4650 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) { 4651 assert_at_safepoint_on_vm_thread(); 4652 4653 if (!free_list_only) { 4654 TearDownRegionSetsClosure cl(&_old_set); 4655 heap_region_iterate(&cl); 4656 4657 // Note that emptying the _young_list is postponed and instead done as 4658 // the first step when rebuilding the regions sets again. The reason for 4659 // this is that during a full GC string deduplication needs to know if 4660 // a collected region was young or old when the full GC was initiated. 4661 } 4662 _hrm.remove_all_free_regions(); 4663 } 4664 4665 void G1CollectedHeap::increase_used(size_t bytes) { 4666 _summary_bytes_used += bytes; 4667 } 4668 4669 void G1CollectedHeap::decrease_used(size_t bytes) { 4670 assert(_summary_bytes_used >= bytes, 4671 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT, 4672 _summary_bytes_used, bytes); 4673 _summary_bytes_used -= bytes; 4674 } 4675 4676 void G1CollectedHeap::set_used(size_t bytes) { 4677 _summary_bytes_used = bytes; 4678 } 4679 4680 class RebuildRegionSetsClosure : public HeapRegionClosure { 4681 private: 4682 bool _free_list_only; 4683 HeapRegionSet* _old_set; 4684 HeapRegionManager* _hrm; 4685 size_t _total_used; 4686 4687 public: 4688 RebuildRegionSetsClosure(bool free_list_only, 4689 HeapRegionSet* old_set, HeapRegionManager* hrm) : 4690 _free_list_only(free_list_only), 4691 _old_set(old_set), _hrm(hrm), _total_used(0) { 4692 assert(_hrm->num_free_regions() == 0, "pre-condition"); 4693 if (!free_list_only) { 4694 assert(_old_set->is_empty(), "pre-condition"); 4695 } 4696 } 4697 4698 bool do_heap_region(HeapRegion* r) { 4699 // After full GC, no region should have a remembered set. 4700 r->rem_set()->clear(true); 4701 if (r->is_empty()) { 4702 // Add free regions to the free list 4703 r->set_free(); 4704 _hrm->insert_into_free_list(r); 4705 } else if (!_free_list_only) { 4706 4707 if (r->is_humongous()) { 4708 // We ignore humongous regions. We left the humongous set unchanged. 4709 } else { 4710 assert(r->is_young() || r->is_free() || r->is_old(), "invariant"); 4711 // We now move all (non-humongous, non-old) regions to old gen, and register them as such. 4712 r->move_to_old(); 4713 _old_set->add(r); 4714 } 4715 _total_used += r->used(); 4716 } 4717 4718 return false; 4719 } 4720 4721 size_t total_used() { 4722 return _total_used; 4723 } 4724 }; 4725 4726 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { 4727 assert_at_safepoint_on_vm_thread(); 4728 4729 if (!free_list_only) { 4730 _eden.clear(); 4731 _survivor.clear(); 4732 } 4733 4734 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm); 4735 heap_region_iterate(&cl); 4736 4737 if (!free_list_only) { 4738 set_used(cl.total_used()); 4739 if (_archive_allocator != NULL) { 4740 _archive_allocator->clear_used(); 4741 } 4742 } 4743 assert(used_unlocked() == recalculate_used(), 4744 "inconsistent used_unlocked(), " 4745 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT, 4746 used_unlocked(), recalculate_used()); 4747 } 4748 4749 bool G1CollectedHeap::is_in_closed_subset(const void* p) const { 4750 HeapRegion* hr = heap_region_containing(p); 4751 return hr->is_in(p); 4752 } 4753 4754 // Methods for the mutator alloc region 4755 4756 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 4757 bool force) { 4758 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 4759 bool should_allocate = g1_policy()->should_allocate_mutator_region(); 4760 if (force || should_allocate) { 4761 HeapRegion* new_alloc_region = new_region(word_size, 4762 false /* is_old */, 4763 false /* do_expand */); 4764 if (new_alloc_region != NULL) { 4765 set_region_short_lived_locked(new_alloc_region); 4766 _hr_printer.alloc(new_alloc_region, !should_allocate); 4767 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region); 4768 _g1_policy->remset_tracker()->update_at_allocate(new_alloc_region); 4769 return new_alloc_region; 4770 } 4771 } 4772 return NULL; 4773 } 4774 4775 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 4776 size_t allocated_bytes) { 4777 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 4778 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden"); 4779 4780 collection_set()->add_eden_region(alloc_region); 4781 increase_used(allocated_bytes); 4782 _hr_printer.retire(alloc_region); 4783 // We update the eden sizes here, when the region is retired, 4784 // instead of when it's allocated, since this is the point that its 4785 // used space has been recored in _summary_bytes_used. 4786 g1mm()->update_eden_size(); 4787 } 4788 4789 // Methods for the GC alloc regions 4790 4791 bool G1CollectedHeap::has_more_regions(InCSetState dest) { 4792 if (dest.is_old()) { 4793 return true; 4794 } else { 4795 return survivor_regions_count() < g1_policy()->max_survivor_regions(); 4796 } 4797 } 4798 4799 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) { 4800 assert(FreeList_lock->owned_by_self(), "pre-condition"); 4801 4802 if (!has_more_regions(dest)) { 4803 return NULL; 4804 } 4805 4806 const bool is_survivor = dest.is_young(); 4807 4808 HeapRegion* new_alloc_region = new_region(word_size, 4809 !is_survivor, 4810 true /* do_expand */); 4811 if (new_alloc_region != NULL) { 4812 if (is_survivor) { 4813 new_alloc_region->set_survivor(); 4814 _survivor.add(new_alloc_region); 4815 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region); 4816 } else { 4817 new_alloc_region->set_old(); 4818 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region); 4819 } 4820 _g1_policy->remset_tracker()->update_at_allocate(new_alloc_region); 4821 _hr_printer.alloc(new_alloc_region); 4822 bool during_im = collector_state()->in_initial_mark_gc(); 4823 new_alloc_region->note_start_of_copying(during_im); 4824 return new_alloc_region; 4825 } 4826 return NULL; 4827 } 4828 4829 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 4830 size_t allocated_bytes, 4831 InCSetState dest) { 4832 bool during_im = collector_state()->in_initial_mark_gc(); 4833 alloc_region->note_end_of_copying(during_im); 4834 g1_policy()->record_bytes_copied_during_gc(allocated_bytes); 4835 if (dest.is_old()) { 4836 _old_set.add(alloc_region); 4837 } 4838 _hr_printer.retire(alloc_region); 4839 } 4840 4841 HeapRegion* G1CollectedHeap::alloc_highest_free_region() { 4842 bool expanded = false; 4843 uint index = _hrm.find_highest_free(&expanded); 4844 4845 if (index != G1_NO_HRM_INDEX) { 4846 if (expanded) { 4847 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B", 4848 HeapRegion::GrainWords * HeapWordSize); 4849 } 4850 _hrm.allocate_free_regions_starting_at(index, 1); 4851 return region_at(index); 4852 } 4853 return NULL; 4854 } 4855 4856 // Optimized nmethod scanning 4857 4858 class RegisterNMethodOopClosure: public OopClosure { 4859 G1CollectedHeap* _g1h; 4860 nmethod* _nm; 4861 4862 template <class T> void do_oop_work(T* p) { 4863 T heap_oop = RawAccess<>::oop_load(p); 4864 if (!CompressedOops::is_null(heap_oop)) { 4865 oop obj = CompressedOops::decode_not_null(heap_oop); 4866 HeapRegion* hr = _g1h->heap_region_containing(obj); 4867 assert(!hr->is_continues_humongous(), 4868 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 4869 " starting at " HR_FORMAT, 4870 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 4871 4872 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries. 4873 hr->add_strong_code_root_locked(_nm); 4874 } 4875 } 4876 4877 public: 4878 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 4879 _g1h(g1h), _nm(nm) {} 4880 4881 void do_oop(oop* p) { do_oop_work(p); } 4882 void do_oop(narrowOop* p) { do_oop_work(p); } 4883 }; 4884 4885 class UnregisterNMethodOopClosure: public OopClosure { 4886 G1CollectedHeap* _g1h; 4887 nmethod* _nm; 4888 4889 template <class T> void do_oop_work(T* p) { 4890 T heap_oop = RawAccess<>::oop_load(p); 4891 if (!CompressedOops::is_null(heap_oop)) { 4892 oop obj = CompressedOops::decode_not_null(heap_oop); 4893 HeapRegion* hr = _g1h->heap_region_containing(obj); 4894 assert(!hr->is_continues_humongous(), 4895 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 4896 " starting at " HR_FORMAT, 4897 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 4898 4899 hr->remove_strong_code_root(_nm); 4900 } 4901 } 4902 4903 public: 4904 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 4905 _g1h(g1h), _nm(nm) {} 4906 4907 void do_oop(oop* p) { do_oop_work(p); } 4908 void do_oop(narrowOop* p) { do_oop_work(p); } 4909 }; 4910 4911 // Returns true if the reference points to an object that 4912 // can move in an incremental collection. 4913 bool G1CollectedHeap::is_scavengable(oop obj) { 4914 HeapRegion* hr = heap_region_containing(obj); 4915 return !hr->is_pinned(); 4916 } 4917 4918 void G1CollectedHeap::register_nmethod(nmethod* nm) { 4919 guarantee(nm != NULL, "sanity"); 4920 RegisterNMethodOopClosure reg_cl(this, nm); 4921 nm->oops_do(®_cl); 4922 } 4923 4924 void G1CollectedHeap::unregister_nmethod(nmethod* nm) { 4925 guarantee(nm != NULL, "sanity"); 4926 UnregisterNMethodOopClosure reg_cl(this, nm); 4927 nm->oops_do(®_cl, true); 4928 } 4929 4930 void G1CollectedHeap::purge_code_root_memory() { 4931 double purge_start = os::elapsedTime(); 4932 G1CodeRootSet::purge(); 4933 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0; 4934 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms); 4935 } 4936 4937 class RebuildStrongCodeRootClosure: public CodeBlobClosure { 4938 G1CollectedHeap* _g1h; 4939 4940 public: 4941 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) : 4942 _g1h(g1h) {} 4943 4944 void do_code_blob(CodeBlob* cb) { 4945 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL; 4946 if (nm == NULL) { 4947 return; 4948 } 4949 4950 if (ScavengeRootsInCode) { 4951 _g1h->register_nmethod(nm); 4952 } 4953 } 4954 }; 4955 4956 void G1CollectedHeap::rebuild_strong_code_roots() { 4957 RebuildStrongCodeRootClosure blob_cl(this); 4958 CodeCache::blobs_do(&blob_cl); 4959 } 4960 4961 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() { 4962 GrowableArray<GCMemoryManager*> memory_managers(2); 4963 memory_managers.append(&_memory_manager); 4964 memory_managers.append(&_full_gc_memory_manager); 4965 return memory_managers; 4966 } 4967 4968 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() { 4969 GrowableArray<MemoryPool*> memory_pools(3); 4970 memory_pools.append(_eden_pool); 4971 memory_pools.append(_survivor_pool); 4972 memory_pools.append(_old_pool); 4973 return memory_pools; 4974 }