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 "classfile/symbolTable.hpp" 29 #include "code/codeCache.hpp" 30 #include "code/icBuffer.hpp" 31 #include "gc/g1/bufferingOopClosure.hpp" 32 #include "gc/g1/concurrentMarkThread.inline.hpp" 33 #include "gc/g1/g1Allocator.inline.hpp" 34 #include "gc/g1/g1CollectedHeap.inline.hpp" 35 #include "gc/g1/g1CollectionSet.hpp" 36 #include "gc/g1/g1CollectorPolicy.hpp" 37 #include "gc/g1/g1CollectorState.hpp" 38 #include "gc/g1/g1ConcurrentRefine.hpp" 39 #include "gc/g1/g1ConcurrentRefineThread.hpp" 40 #include "gc/g1/g1DefaultPolicy.hpp" 41 #include "gc/g1/g1EvacStats.inline.hpp" 42 #include "gc/g1/g1FullCollector.hpp" 43 #include "gc/g1/g1GCPhaseTimes.hpp" 44 #include "gc/g1/g1HeapSizingPolicy.hpp" 45 #include "gc/g1/g1HeapTransition.hpp" 46 #include "gc/g1/g1HeapVerifier.hpp" 47 #include "gc/g1/g1HotCardCache.hpp" 48 #include "gc/g1/g1MemoryPool.hpp" 49 #include "gc/g1/g1OopClosures.inline.hpp" 50 #include "gc/g1/g1ParScanThreadState.inline.hpp" 51 #include "gc/g1/g1Policy.hpp" 52 #include "gc/g1/g1RegionToSpaceMapper.hpp" 53 #include "gc/g1/g1RemSet.hpp" 54 #include "gc/g1/g1RootClosures.hpp" 55 #include "gc/g1/g1RootProcessor.hpp" 56 #include "gc/g1/g1SATBCardTableModRefBS.hpp" 57 #include "gc/g1/g1StringDedup.hpp" 58 #include "gc/g1/g1YCTypes.hpp" 59 #include "gc/g1/g1YoungRemSetSamplingThread.hpp" 60 #include "gc/g1/heapRegion.inline.hpp" 61 #include "gc/g1/heapRegionRemSet.hpp" 62 #include "gc/g1/heapRegionSet.inline.hpp" 63 #include "gc/g1/vm_operations_g1.hpp" 64 #include "gc/shared/adaptiveSizePolicy.hpp" 65 #include "gc/shared/gcHeapSummary.hpp" 66 #include "gc/shared/gcId.hpp" 67 #include "gc/shared/gcLocker.inline.hpp" 68 #include "gc/shared/gcTimer.hpp" 69 #include "gc/shared/gcTrace.hpp" 70 #include "gc/shared/gcTraceTime.inline.hpp" 71 #include "gc/shared/generationSpec.hpp" 72 #include "gc/shared/isGCActiveMark.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/resourceArea.hpp" 82 #include "oops/oop.inline.hpp" 83 #include "prims/resolvedMethodTable.hpp" 84 #include "runtime/atomic.hpp" 85 #include "runtime/init.hpp" 86 #include "runtime/orderAccess.inline.hpp" 87 #include "runtime/threadSMR.hpp" 88 #include "runtime/vmThread.hpp" 89 #include "utilities/align.hpp" 90 #include "utilities/globalDefinitions.hpp" 91 #include "utilities/stack.inline.hpp" 92 93 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0; 94 95 // INVARIANTS/NOTES 96 // 97 // All allocation activity covered by the G1CollectedHeap interface is 98 // serialized by acquiring the HeapLock. This happens in mem_allocate 99 // and allocate_new_tlab, which are the "entry" points to the 100 // allocation code from the rest of the JVM. (Note that this does not 101 // apply to TLAB allocation, which is not part of this interface: it 102 // is done by clients of this interface.) 103 104 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure { 105 private: 106 size_t _num_dirtied; 107 G1CollectedHeap* _g1h; 108 G1CardTable* _g1_ct; 109 110 HeapRegion* region_for_card(jbyte* card_ptr) const { 111 return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr)); 112 } 113 114 bool will_become_free(HeapRegion* hr) const { 115 // A region will be freed by free_collection_set if the region is in the 116 // collection set and has not had an evacuation failure. 117 return _g1h->is_in_cset(hr) && !hr->evacuation_failed(); 118 } 119 120 public: 121 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(), 122 _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { } 123 124 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 125 HeapRegion* hr = region_for_card(card_ptr); 126 127 // Should only dirty cards in regions that won't be freed. 128 if (!will_become_free(hr)) { 129 *card_ptr = G1CardTable::dirty_card_val(); 130 _num_dirtied++; 131 } 132 133 return true; 134 } 135 136 size_t num_dirtied() const { return _num_dirtied; } 137 }; 138 139 140 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) { 141 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions); 142 } 143 144 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) { 145 // The from card cache is not the memory that is actually committed. So we cannot 146 // take advantage of the zero_filled parameter. 147 reset_from_card_cache(start_idx, num_regions); 148 } 149 150 151 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index, 152 MemRegion mr) { 153 return new HeapRegion(hrs_index, bot(), mr); 154 } 155 156 // Private methods. 157 158 HeapRegion* 159 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) { 160 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 161 while (!_secondary_free_list.is_empty() || free_regions_coming()) { 162 if (!_secondary_free_list.is_empty()) { 163 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : " 164 "secondary_free_list has %u entries", 165 _secondary_free_list.length()); 166 // It looks as if there are free regions available on the 167 // secondary_free_list. Let's move them to the free_list and try 168 // again to allocate from it. 169 append_secondary_free_list(); 170 171 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not " 172 "empty we should have moved at least one entry to the free_list"); 173 HeapRegion* res = _hrm.allocate_free_region(is_old); 174 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : " 175 "allocated " HR_FORMAT " from secondary_free_list", 176 HR_FORMAT_PARAMS(res)); 177 return res; 178 } 179 180 // Wait here until we get notified either when (a) there are no 181 // more free regions coming or (b) some regions have been moved on 182 // the secondary_free_list. 183 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 184 } 185 186 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : " 187 "could not allocate from secondary_free_list"); 188 return NULL; 189 } 190 191 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) { 192 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords, 193 "the only time we use this to allocate a humongous region is " 194 "when we are allocating a single humongous region"); 195 196 HeapRegion* res; 197 if (G1StressConcRegionFreeing) { 198 if (!_secondary_free_list.is_empty()) { 199 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : " 200 "forced to look at the secondary_free_list"); 201 res = new_region_try_secondary_free_list(is_old); 202 if (res != NULL) { 203 return res; 204 } 205 } 206 } 207 208 res = _hrm.allocate_free_region(is_old); 209 210 if (res == NULL) { 211 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : " 212 "res == NULL, trying the secondary_free_list"); 213 res = new_region_try_secondary_free_list(is_old); 214 } 215 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) { 216 // Currently, only attempts to allocate GC alloc regions set 217 // do_expand to true. So, we should only reach here during a 218 // safepoint. If this assumption changes we might have to 219 // reconsider the use of _expand_heap_after_alloc_failure. 220 assert(SafepointSynchronize::is_at_safepoint(), "invariant"); 221 222 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B", 223 word_size * HeapWordSize); 224 225 if (expand(word_size * HeapWordSize)) { 226 // Given that expand() succeeded in expanding the heap, and we 227 // always expand the heap by an amount aligned to the heap 228 // region size, the free list should in theory not be empty. 229 // In either case allocate_free_region() will check for NULL. 230 res = _hrm.allocate_free_region(is_old); 231 } else { 232 _expand_heap_after_alloc_failure = false; 233 } 234 } 235 return res; 236 } 237 238 HeapWord* 239 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first, 240 uint num_regions, 241 size_t word_size) { 242 assert(first != G1_NO_HRM_INDEX, "pre-condition"); 243 assert(is_humongous(word_size), "word_size should be humongous"); 244 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition"); 245 246 // Index of last region in the series. 247 uint last = first + num_regions - 1; 248 249 // We need to initialize the region(s) we just discovered. This is 250 // a bit tricky given that it can happen concurrently with 251 // refinement threads refining cards on these regions and 252 // potentially wanting to refine the BOT as they are scanning 253 // those cards (this can happen shortly after a cleanup; see CR 254 // 6991377). So we have to set up the region(s) carefully and in 255 // a specific order. 256 257 // The word size sum of all the regions we will allocate. 258 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords; 259 assert(word_size <= word_size_sum, "sanity"); 260 261 // This will be the "starts humongous" region. 262 HeapRegion* first_hr = region_at(first); 263 // The header of the new object will be placed at the bottom of 264 // the first region. 265 HeapWord* new_obj = first_hr->bottom(); 266 // This will be the new top of the new object. 267 HeapWord* obj_top = new_obj + word_size; 268 269 // First, we need to zero the header of the space that we will be 270 // allocating. When we update top further down, some refinement 271 // threads might try to scan the region. By zeroing the header we 272 // ensure that any thread that will try to scan the region will 273 // come across the zero klass word and bail out. 274 // 275 // NOTE: It would not have been correct to have used 276 // CollectedHeap::fill_with_object() and make the space look like 277 // an int array. The thread that is doing the allocation will 278 // later update the object header to a potentially different array 279 // type and, for a very short period of time, the klass and length 280 // fields will be inconsistent. This could cause a refinement 281 // thread to calculate the object size incorrectly. 282 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0); 283 284 // Next, pad out the unused tail of the last region with filler 285 // objects, for improved usage accounting. 286 // How many words we use for filler objects. 287 size_t word_fill_size = word_size_sum - word_size; 288 289 // How many words memory we "waste" which cannot hold a filler object. 290 size_t words_not_fillable = 0; 291 292 if (word_fill_size >= min_fill_size()) { 293 fill_with_objects(obj_top, word_fill_size); 294 } else if (word_fill_size > 0) { 295 // We have space to fill, but we cannot fit an object there. 296 words_not_fillable = word_fill_size; 297 word_fill_size = 0; 298 } 299 300 // We will set up the first region as "starts humongous". This 301 // will also update the BOT covering all the regions to reflect 302 // that there is a single object that starts at the bottom of the 303 // first region. 304 first_hr->set_starts_humongous(obj_top, word_fill_size); 305 // Then, if there are any, we will set up the "continues 306 // humongous" regions. 307 HeapRegion* hr = NULL; 308 for (uint i = first + 1; i <= last; ++i) { 309 hr = region_at(i); 310 hr->set_continues_humongous(first_hr); 311 } 312 313 // Up to this point no concurrent thread would have been able to 314 // do any scanning on any region in this series. All the top 315 // fields still point to bottom, so the intersection between 316 // [bottom,top] and [card_start,card_end] will be empty. Before we 317 // update the top fields, we'll do a storestore to make sure that 318 // no thread sees the update to top before the zeroing of the 319 // object header and the BOT initialization. 320 OrderAccess::storestore(); 321 322 // Now, we will update the top fields of the "continues humongous" 323 // regions except the last one. 324 for (uint i = first; i < last; ++i) { 325 hr = region_at(i); 326 hr->set_top(hr->end()); 327 } 328 329 hr = region_at(last); 330 // If we cannot fit a filler object, we must set top to the end 331 // of the humongous object, otherwise we cannot iterate the heap 332 // and the BOT will not be complete. 333 hr->set_top(hr->end() - words_not_fillable); 334 335 assert(hr->bottom() < obj_top && obj_top <= hr->end(), 336 "obj_top should be in last region"); 337 338 _verifier->check_bitmaps("Humongous Region Allocation", first_hr); 339 340 assert(words_not_fillable == 0 || 341 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(), 342 "Miscalculation in humongous allocation"); 343 344 increase_used((word_size_sum - words_not_fillable) * HeapWordSize); 345 346 for (uint i = first; i <= last; ++i) { 347 hr = region_at(i); 348 _humongous_set.add(hr); 349 _hr_printer.alloc(hr); 350 } 351 352 return new_obj; 353 } 354 355 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) { 356 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size); 357 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords; 358 } 359 360 // If could fit into free regions w/o expansion, try. 361 // Otherwise, if can expand, do so. 362 // Otherwise, if using ex regions might help, try with ex given back. 363 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) { 364 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 365 366 _verifier->verify_region_sets_optional(); 367 368 uint first = G1_NO_HRM_INDEX; 369 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size); 370 371 if (obj_regions == 1) { 372 // Only one region to allocate, try to use a fast path by directly allocating 373 // from the free lists. Do not try to expand here, we will potentially do that 374 // later. 375 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */); 376 if (hr != NULL) { 377 first = hr->hrm_index(); 378 } 379 } else { 380 // We can't allocate humongous regions spanning more than one region while 381 // cleanupComplete() is running, since some of the regions we find to be 382 // empty might not yet be added to the free list. It is not straightforward 383 // to know in which list they are on so that we can remove them. We only 384 // need to do this if we need to allocate more than one region to satisfy the 385 // current humongous allocation request. If we are only allocating one region 386 // we use the one-region region allocation code (see above), that already 387 // potentially waits for regions from the secondary free list. 388 wait_while_free_regions_coming(); 389 append_secondary_free_list_if_not_empty_with_lock(); 390 391 // Policy: Try only empty regions (i.e. already committed first). Maybe we 392 // are lucky enough to find some. 393 first = _hrm.find_contiguous_only_empty(obj_regions); 394 if (first != G1_NO_HRM_INDEX) { 395 _hrm.allocate_free_regions_starting_at(first, obj_regions); 396 } 397 } 398 399 if (first == G1_NO_HRM_INDEX) { 400 // Policy: We could not find enough regions for the humongous object in the 401 // free list. Look through the heap to find a mix of free and uncommitted regions. 402 // If so, try expansion. 403 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions); 404 if (first != G1_NO_HRM_INDEX) { 405 // We found something. Make sure these regions are committed, i.e. expand 406 // the heap. Alternatively we could do a defragmentation GC. 407 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B", 408 word_size * HeapWordSize); 409 410 _hrm.expand_at(first, obj_regions, workers()); 411 g1_policy()->record_new_heap_size(num_regions()); 412 413 #ifdef ASSERT 414 for (uint i = first; i < first + obj_regions; ++i) { 415 HeapRegion* hr = region_at(i); 416 assert(hr->is_free(), "sanity"); 417 assert(hr->is_empty(), "sanity"); 418 assert(is_on_master_free_list(hr), "sanity"); 419 } 420 #endif 421 _hrm.allocate_free_regions_starting_at(first, obj_regions); 422 } else { 423 // Policy: Potentially trigger a defragmentation GC. 424 } 425 } 426 427 HeapWord* result = NULL; 428 if (first != G1_NO_HRM_INDEX) { 429 result = humongous_obj_allocate_initialize_regions(first, obj_regions, word_size); 430 assert(result != NULL, "it should always return a valid result"); 431 432 // A successful humongous object allocation changes the used space 433 // information of the old generation so we need to recalculate the 434 // sizes and update the jstat counters here. 435 g1mm()->update_sizes(); 436 } 437 438 _verifier->verify_region_sets_optional(); 439 440 return result; 441 } 442 443 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) { 444 assert_heap_not_locked_and_not_at_safepoint(); 445 assert(!is_humongous(word_size), "we do not allow humongous TLABs"); 446 447 return attempt_allocation(word_size); 448 } 449 450 HeapWord* 451 G1CollectedHeap::mem_allocate(size_t word_size, 452 bool* gc_overhead_limit_was_exceeded) { 453 assert_heap_not_locked_and_not_at_safepoint(); 454 455 if (is_humongous(word_size)) { 456 return attempt_allocation_humongous(word_size); 457 } 458 return attempt_allocation(word_size); 459 } 460 461 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) { 462 ResourceMark rm; // For retrieving the thread names in log messages. 463 464 // Make sure you read the note in attempt_allocation_humongous(). 465 466 assert_heap_not_locked_and_not_at_safepoint(); 467 assert(!is_humongous(word_size), "attempt_allocation_slow() should not " 468 "be called for humongous allocation requests"); 469 470 // We should only get here after the first-level allocation attempt 471 // (attempt_allocation()) failed to allocate. 472 473 // We will loop until a) we manage to successfully perform the 474 // allocation or b) we successfully schedule a collection which 475 // fails to perform the allocation. b) is the only case when we'll 476 // return NULL. 477 HeapWord* result = NULL; 478 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 479 bool should_try_gc; 480 uint gc_count_before; 481 482 { 483 MutexLockerEx x(Heap_lock); 484 result = _allocator->attempt_allocation_locked(word_size); 485 if (result != NULL) { 486 return result; 487 } 488 489 // If the GCLocker is active and we are bound for a GC, try expanding young gen. 490 // This is different to when only GCLocker::needs_gc() is set: try to avoid 491 // waiting because the GCLocker is active to not wait too long. 492 if (GCLocker::is_active_and_needs_gc() && g1_policy()->can_expand_young_list()) { 493 // No need for an ergo message here, can_expand_young_list() does this when 494 // it returns true. 495 result = _allocator->attempt_allocation_force(word_size); 496 if (result != NULL) { 497 return result; 498 } 499 } 500 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until 501 // the GCLocker initiated GC has been performed and then retry. This includes 502 // the case when the GC Locker is not active but has not been performed. 503 should_try_gc = !GCLocker::needs_gc(); 504 // Read the GC count while still holding the Heap_lock. 505 gc_count_before = total_collections(); 506 } 507 508 if (should_try_gc) { 509 bool succeeded; 510 result = do_collection_pause(word_size, gc_count_before, &succeeded, 511 GCCause::_g1_inc_collection_pause); 512 if (result != NULL) { 513 assert(succeeded, "only way to get back a non-NULL result"); 514 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT, 515 Thread::current()->name(), p2i(result)); 516 return result; 517 } 518 519 if (succeeded) { 520 // We successfully scheduled a collection which failed to allocate. No 521 // point in trying to allocate further. We'll just return NULL. 522 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate " 523 SIZE_FORMAT " words", Thread::current()->name(), word_size); 524 return NULL; 525 } 526 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words", 527 Thread::current()->name(), word_size); 528 } else { 529 // Failed to schedule a collection. 530 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 531 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating " 532 SIZE_FORMAT " words", Thread::current()->name(), word_size); 533 return NULL; 534 } 535 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name()); 536 // The GCLocker is either active or the GCLocker initiated 537 // GC has not yet been performed. Stall until it is and 538 // then retry the allocation. 539 GCLocker::stall_until_clear(); 540 gclocker_retry_count += 1; 541 } 542 543 // We can reach here if we were unsuccessful in scheduling a 544 // collection (because another thread beat us to it) or if we were 545 // stalled due to the GC locker. In either can we should retry the 546 // allocation attempt in case another thread successfully 547 // performed a collection and reclaimed enough space. We do the 548 // first attempt (without holding the Heap_lock) here and the 549 // follow-on attempt will be at the start of the next loop 550 // iteration (after taking the Heap_lock). 551 552 result = _allocator->attempt_allocation(word_size); 553 if (result != NULL) { 554 return result; 555 } 556 557 // Give a warning if we seem to be looping forever. 558 if ((QueuedAllocationWarningCount > 0) && 559 (try_count % QueuedAllocationWarningCount == 0)) { 560 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words", 561 Thread::current()->name(), try_count, word_size); 562 } 563 } 564 565 ShouldNotReachHere(); 566 return NULL; 567 } 568 569 void G1CollectedHeap::begin_archive_alloc_range(bool open) { 570 assert_at_safepoint_on_vm_thread(); 571 if (_archive_allocator == NULL) { 572 _archive_allocator = G1ArchiveAllocator::create_allocator(this, open); 573 } 574 } 575 576 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) { 577 // Allocations in archive regions cannot be of a size that would be considered 578 // humongous even for a minimum-sized region, because G1 region sizes/boundaries 579 // may be different at archive-restore time. 580 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words()); 581 } 582 583 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) { 584 assert_at_safepoint_on_vm_thread(); 585 assert(_archive_allocator != NULL, "_archive_allocator not initialized"); 586 if (is_archive_alloc_too_large(word_size)) { 587 return NULL; 588 } 589 return _archive_allocator->archive_mem_allocate(word_size); 590 } 591 592 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges, 593 size_t end_alignment_in_bytes) { 594 assert_at_safepoint_on_vm_thread(); 595 assert(_archive_allocator != NULL, "_archive_allocator not initialized"); 596 597 // Call complete_archive to do the real work, filling in the MemRegion 598 // array with the archive regions. 599 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes); 600 delete _archive_allocator; 601 _archive_allocator = NULL; 602 } 603 604 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) { 605 assert(ranges != NULL, "MemRegion array NULL"); 606 assert(count != 0, "No MemRegions provided"); 607 MemRegion reserved = _hrm.reserved(); 608 for (size_t i = 0; i < count; i++) { 609 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) { 610 return false; 611 } 612 } 613 return true; 614 } 615 616 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, 617 size_t count, 618 bool open) { 619 assert(!is_init_completed(), "Expect to be called at JVM init time"); 620 assert(ranges != NULL, "MemRegion array NULL"); 621 assert(count != 0, "No MemRegions provided"); 622 MutexLockerEx x(Heap_lock); 623 624 MemRegion reserved = _hrm.reserved(); 625 HeapWord* prev_last_addr = NULL; 626 HeapRegion* prev_last_region = NULL; 627 628 // Temporarily disable pretouching of heap pages. This interface is used 629 // when mmap'ing archived heap data in, so pre-touching is wasted. 630 FlagSetting fs(AlwaysPreTouch, false); 631 632 // Enable archive object checking used by G1MarkSweep. We have to let it know 633 // about each archive range, so that objects in those ranges aren't marked. 634 G1ArchiveAllocator::enable_archive_object_check(); 635 636 // For each specified MemRegion range, allocate the corresponding G1 637 // regions and mark them as archive regions. We expect the ranges 638 // in ascending starting address order, without overlap. 639 for (size_t i = 0; i < count; i++) { 640 MemRegion curr_range = ranges[i]; 641 HeapWord* start_address = curr_range.start(); 642 size_t word_size = curr_range.word_size(); 643 HeapWord* last_address = curr_range.last(); 644 size_t commits = 0; 645 646 guarantee(reserved.contains(start_address) && reserved.contains(last_address), 647 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 648 p2i(start_address), p2i(last_address)); 649 guarantee(start_address > prev_last_addr, 650 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 651 p2i(start_address), p2i(prev_last_addr)); 652 prev_last_addr = last_address; 653 654 // Check for ranges that start in the same G1 region in which the previous 655 // range ended, and adjust the start address so we don't try to allocate 656 // the same region again. If the current range is entirely within that 657 // region, skip it, just adjusting the recorded top. 658 HeapRegion* start_region = _hrm.addr_to_region(start_address); 659 if ((prev_last_region != NULL) && (start_region == prev_last_region)) { 660 start_address = start_region->end(); 661 if (start_address > last_address) { 662 increase_used(word_size * HeapWordSize); 663 start_region->set_top(last_address + 1); 664 continue; 665 } 666 start_region->set_top(start_address); 667 curr_range = MemRegion(start_address, last_address + 1); 668 start_region = _hrm.addr_to_region(start_address); 669 } 670 671 // Perform the actual region allocation, exiting if it fails. 672 // Then note how much new space we have allocated. 673 if (!_hrm.allocate_containing_regions(curr_range, &commits, workers())) { 674 return false; 675 } 676 increase_used(word_size * HeapWordSize); 677 if (commits != 0) { 678 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B", 679 HeapRegion::GrainWords * HeapWordSize * commits); 680 681 } 682 683 // Mark each G1 region touched by the range as archive, add it to 684 // the old set, and set top. 685 HeapRegion* curr_region = _hrm.addr_to_region(start_address); 686 HeapRegion* last_region = _hrm.addr_to_region(last_address); 687 prev_last_region = last_region; 688 689 while (curr_region != NULL) { 690 assert(curr_region->is_empty() && !curr_region->is_pinned(), 691 "Region already in use (index %u)", curr_region->hrm_index()); 692 if (open) { 693 curr_region->set_open_archive(); 694 } else { 695 curr_region->set_closed_archive(); 696 } 697 _hr_printer.alloc(curr_region); 698 _old_set.add(curr_region); 699 HeapWord* top; 700 HeapRegion* next_region; 701 if (curr_region != last_region) { 702 top = curr_region->end(); 703 next_region = _hrm.next_region_in_heap(curr_region); 704 } else { 705 top = last_address + 1; 706 next_region = NULL; 707 } 708 curr_region->set_top(top); 709 curr_region->set_first_dead(top); 710 curr_region->set_end_of_live(top); 711 curr_region = next_region; 712 } 713 714 // Notify mark-sweep of the archive 715 G1ArchiveAllocator::set_range_archive(curr_range, open); 716 } 717 return true; 718 } 719 720 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) { 721 assert(!is_init_completed(), "Expect to be called at JVM init time"); 722 assert(ranges != NULL, "MemRegion array NULL"); 723 assert(count != 0, "No MemRegions provided"); 724 MemRegion reserved = _hrm.reserved(); 725 HeapWord *prev_last_addr = NULL; 726 HeapRegion* prev_last_region = NULL; 727 728 // For each MemRegion, create filler objects, if needed, in the G1 regions 729 // that contain the address range. The address range actually within the 730 // MemRegion will not be modified. That is assumed to have been initialized 731 // elsewhere, probably via an mmap of archived heap data. 732 MutexLockerEx x(Heap_lock); 733 for (size_t i = 0; i < count; i++) { 734 HeapWord* start_address = ranges[i].start(); 735 HeapWord* last_address = ranges[i].last(); 736 737 assert(reserved.contains(start_address) && reserved.contains(last_address), 738 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 739 p2i(start_address), p2i(last_address)); 740 assert(start_address > prev_last_addr, 741 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 742 p2i(start_address), p2i(prev_last_addr)); 743 744 HeapRegion* start_region = _hrm.addr_to_region(start_address); 745 HeapRegion* last_region = _hrm.addr_to_region(last_address); 746 HeapWord* bottom_address = start_region->bottom(); 747 748 // Check for a range beginning in the same region in which the 749 // previous one ended. 750 if (start_region == prev_last_region) { 751 bottom_address = prev_last_addr + 1; 752 } 753 754 // Verify that the regions were all marked as archive regions by 755 // alloc_archive_regions. 756 HeapRegion* curr_region = start_region; 757 while (curr_region != NULL) { 758 guarantee(curr_region->is_archive(), 759 "Expected archive region at index %u", curr_region->hrm_index()); 760 if (curr_region != last_region) { 761 curr_region = _hrm.next_region_in_heap(curr_region); 762 } else { 763 curr_region = NULL; 764 } 765 } 766 767 prev_last_addr = last_address; 768 prev_last_region = last_region; 769 770 // Fill the memory below the allocated range with dummy object(s), 771 // if the region bottom does not match the range start, or if the previous 772 // range ended within the same G1 region, and there is a gap. 773 if (start_address != bottom_address) { 774 size_t fill_size = pointer_delta(start_address, bottom_address); 775 G1CollectedHeap::fill_with_objects(bottom_address, fill_size); 776 increase_used(fill_size * HeapWordSize); 777 } 778 } 779 } 780 781 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size) { 782 assert_heap_not_locked_and_not_at_safepoint(); 783 assert(!is_humongous(word_size), "attempt_allocation() should not " 784 "be called for humongous allocation requests"); 785 786 HeapWord* result = _allocator->attempt_allocation(word_size); 787 788 if (result == NULL) { 789 result = attempt_allocation_slow(word_size); 790 } 791 assert_heap_not_locked(); 792 if (result != NULL) { 793 dirty_young_block(result, word_size); 794 } 795 return result; 796 } 797 798 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) { 799 assert(!is_init_completed(), "Expect to be called at JVM init time"); 800 assert(ranges != NULL, "MemRegion array NULL"); 801 assert(count != 0, "No MemRegions provided"); 802 MemRegion reserved = _hrm.reserved(); 803 HeapWord* prev_last_addr = NULL; 804 HeapRegion* prev_last_region = NULL; 805 size_t size_used = 0; 806 size_t uncommitted_regions = 0; 807 808 // For each Memregion, free the G1 regions that constitute it, and 809 // notify mark-sweep that the range is no longer to be considered 'archive.' 810 MutexLockerEx x(Heap_lock); 811 for (size_t i = 0; i < count; i++) { 812 HeapWord* start_address = ranges[i].start(); 813 HeapWord* last_address = ranges[i].last(); 814 815 assert(reserved.contains(start_address) && reserved.contains(last_address), 816 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 817 p2i(start_address), p2i(last_address)); 818 assert(start_address > prev_last_addr, 819 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 820 p2i(start_address), p2i(prev_last_addr)); 821 size_used += ranges[i].byte_size(); 822 prev_last_addr = last_address; 823 824 HeapRegion* start_region = _hrm.addr_to_region(start_address); 825 HeapRegion* last_region = _hrm.addr_to_region(last_address); 826 827 // Check for ranges that start in the same G1 region in which the previous 828 // range ended, and adjust the start address so we don't try to free 829 // the same region again. If the current range is entirely within that 830 // region, skip it. 831 if (start_region == prev_last_region) { 832 start_address = start_region->end(); 833 if (start_address > last_address) { 834 continue; 835 } 836 start_region = _hrm.addr_to_region(start_address); 837 } 838 prev_last_region = last_region; 839 840 // After verifying that each region was marked as an archive region by 841 // alloc_archive_regions, set it free and empty and uncommit it. 842 HeapRegion* curr_region = start_region; 843 while (curr_region != NULL) { 844 guarantee(curr_region->is_archive(), 845 "Expected archive region at index %u", curr_region->hrm_index()); 846 uint curr_index = curr_region->hrm_index(); 847 _old_set.remove(curr_region); 848 curr_region->set_free(); 849 curr_region->set_top(curr_region->bottom()); 850 if (curr_region != last_region) { 851 curr_region = _hrm.next_region_in_heap(curr_region); 852 } else { 853 curr_region = NULL; 854 } 855 _hrm.shrink_at(curr_index, 1); 856 uncommitted_regions++; 857 } 858 859 // Notify mark-sweep that this is no longer an archive range. 860 G1ArchiveAllocator::set_range_archive(ranges[i], false); 861 } 862 863 if (uncommitted_regions != 0) { 864 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B", 865 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions); 866 } 867 decrease_used(size_used); 868 } 869 870 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) { 871 ResourceMark rm; // For retrieving the thread names in log messages. 872 873 // The structure of this method has a lot of similarities to 874 // attempt_allocation_slow(). The reason these two were not merged 875 // into a single one is that such a method would require several "if 876 // allocation is not humongous do this, otherwise do that" 877 // conditional paths which would obscure its flow. In fact, an early 878 // version of this code did use a unified method which was harder to 879 // follow and, as a result, it had subtle bugs that were hard to 880 // track down. So keeping these two methods separate allows each to 881 // be more readable. It will be good to keep these two in sync as 882 // much as possible. 883 884 assert_heap_not_locked_and_not_at_safepoint(); 885 assert(is_humongous(word_size), "attempt_allocation_humongous() " 886 "should only be called for humongous allocations"); 887 888 // Humongous objects can exhaust the heap quickly, so we should check if we 889 // need to start a marking cycle at each humongous object allocation. We do 890 // the check before we do the actual allocation. The reason for doing it 891 // before the allocation is that we avoid having to keep track of the newly 892 // allocated memory while we do a GC. 893 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation", 894 word_size)) { 895 collect(GCCause::_g1_humongous_allocation); 896 } 897 898 // We will loop until a) we manage to successfully perform the 899 // allocation or b) we successfully schedule a collection which 900 // fails to perform the allocation. b) is the only case when we'll 901 // return NULL. 902 HeapWord* result = NULL; 903 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 904 bool should_try_gc; 905 uint gc_count_before; 906 907 908 { 909 MutexLockerEx x(Heap_lock); 910 911 // Given that humongous objects are not allocated in young 912 // regions, we'll first try to do the allocation without doing a 913 // collection hoping that there's enough space in the heap. 914 result = humongous_obj_allocate(word_size); 915 if (result != NULL) { 916 size_t size_in_regions = humongous_obj_size_in_regions(word_size); 917 g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes); 918 return result; 919 } 920 921 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until 922 // the GCLocker initiated GC has been performed and then retry. This includes 923 // the case when the GC Locker is not active but has not been performed. 924 should_try_gc = !GCLocker::needs_gc(); 925 // Read the GC count while still holding the Heap_lock. 926 gc_count_before = total_collections(); 927 } 928 929 if (should_try_gc) { 930 bool succeeded; 931 result = do_collection_pause(word_size, gc_count_before, &succeeded, 932 GCCause::_g1_humongous_allocation); 933 if (result != NULL) { 934 assert(succeeded, "only way to get back a non-NULL result"); 935 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT, 936 Thread::current()->name(), p2i(result)); 937 return result; 938 } 939 940 if (succeeded) { 941 // We successfully scheduled a collection which failed to allocate. No 942 // point in trying to allocate further. We'll just return NULL. 943 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate " 944 SIZE_FORMAT " words", Thread::current()->name(), word_size); 945 return NULL; 946 } 947 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "", 948 Thread::current()->name(), word_size); 949 } else { 950 // Failed to schedule a collection. 951 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 952 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating " 953 SIZE_FORMAT " words", Thread::current()->name(), word_size); 954 return NULL; 955 } 956 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name()); 957 // The GCLocker is either active or the GCLocker initiated 958 // GC has not yet been performed. Stall until it is and 959 // then retry the allocation. 960 GCLocker::stall_until_clear(); 961 gclocker_retry_count += 1; 962 } 963 964 965 // We can reach here if we were unsuccessful in scheduling a 966 // collection (because another thread beat us to it) or if we were 967 // stalled due to the GC locker. In either can we should retry the 968 // allocation attempt in case another thread successfully 969 // performed a collection and reclaimed enough space. 970 // Humongous object allocation always needs a lock, so we wait for the retry 971 // in the next iteration of the loop, unlike for the regular iteration case. 972 // Give a warning if we seem to be looping forever. 973 974 if ((QueuedAllocationWarningCount > 0) && 975 (try_count % QueuedAllocationWarningCount == 0)) { 976 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words", 977 Thread::current()->name(), try_count, word_size); 978 } 979 } 980 981 ShouldNotReachHere(); 982 return NULL; 983 } 984 985 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size, 986 bool expect_null_mutator_alloc_region) { 987 assert_at_safepoint_on_vm_thread(); 988 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region, 989 "the current alloc region was unexpectedly found to be non-NULL"); 990 991 if (!is_humongous(word_size)) { 992 return _allocator->attempt_allocation_locked(word_size); 993 } else { 994 HeapWord* result = humongous_obj_allocate(word_size); 995 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) { 996 collector_state()->set_initiate_conc_mark_if_possible(true); 997 } 998 return result; 999 } 1000 1001 ShouldNotReachHere(); 1002 } 1003 1004 class PostCompactionPrinterClosure: public HeapRegionClosure { 1005 private: 1006 G1HRPrinter* _hr_printer; 1007 public: 1008 bool do_heap_region(HeapRegion* hr) { 1009 assert(!hr->is_young(), "not expecting to find young regions"); 1010 _hr_printer->post_compaction(hr); 1011 return false; 1012 } 1013 1014 PostCompactionPrinterClosure(G1HRPrinter* hr_printer) 1015 : _hr_printer(hr_printer) { } 1016 }; 1017 1018 void G1CollectedHeap::print_hrm_post_compaction() { 1019 if (_hr_printer.is_active()) { 1020 PostCompactionPrinterClosure cl(hr_printer()); 1021 heap_region_iterate(&cl); 1022 } 1023 } 1024 1025 void G1CollectedHeap::abort_concurrent_cycle() { 1026 // Note: When we have a more flexible GC logging framework that 1027 // allows us to add optional attributes to a GC log record we 1028 // could consider timing and reporting how long we wait in the 1029 // following two methods. 1030 wait_while_free_regions_coming(); 1031 // If we start the compaction before the CM threads finish 1032 // scanning the root regions we might trip them over as we'll 1033 // be moving objects / updating references. So let's wait until 1034 // they are done. By telling them to abort, they should complete 1035 // early. 1036 _cm->root_regions()->abort(); 1037 _cm->root_regions()->wait_until_scan_finished(); 1038 append_secondary_free_list_if_not_empty_with_lock(); 1039 1040 // Disable discovery and empty the discovered lists 1041 // for the CM ref processor. 1042 ref_processor_cm()->disable_discovery(); 1043 ref_processor_cm()->abandon_partial_discovery(); 1044 ref_processor_cm()->verify_no_references_recorded(); 1045 1046 // Abandon current iterations of concurrent marking and concurrent 1047 // refinement, if any are in progress. 1048 concurrent_mark()->abort(); 1049 } 1050 1051 void G1CollectedHeap::prepare_heap_for_full_collection() { 1052 // Make sure we'll choose a new allocation region afterwards. 1053 _allocator->release_mutator_alloc_region(); 1054 _allocator->abandon_gc_alloc_regions(); 1055 g1_rem_set()->cleanupHRRS(); 1056 1057 // We may have added regions to the current incremental collection 1058 // set between the last GC or pause and now. We need to clear the 1059 // incremental collection set and then start rebuilding it afresh 1060 // after this full GC. 1061 abandon_collection_set(collection_set()); 1062 1063 tear_down_region_sets(false /* free_list_only */); 1064 collector_state()->set_gcs_are_young(true); 1065 } 1066 1067 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) { 1068 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant"); 1069 assert(used() == recalculate_used(), "Should be equal"); 1070 _verifier->verify_region_sets_optional(); 1071 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull); 1072 _verifier->check_bitmaps("Full GC Start"); 1073 } 1074 1075 void G1CollectedHeap::prepare_heap_for_mutators() { 1076 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 1077 ClassLoaderDataGraph::purge(); 1078 MetaspaceAux::verify_metrics(); 1079 1080 // Prepare heap for normal collections. 1081 assert(num_free_regions() == 0, "we should not have added any free regions"); 1082 rebuild_region_sets(false /* free_list_only */); 1083 abort_refinement(); 1084 resize_if_necessary_after_full_collection(); 1085 1086 // Rebuild the strong code root lists for each region 1087 rebuild_strong_code_roots(); 1088 1089 // Start a new incremental collection set for the next pause 1090 start_new_collection_set(); 1091 1092 _allocator->init_mutator_alloc_region(); 1093 1094 // Post collection state updates. 1095 MetaspaceGC::compute_new_size(); 1096 } 1097 1098 void G1CollectedHeap::abort_refinement() { 1099 if (_hot_card_cache->use_cache()) { 1100 _hot_card_cache->reset_hot_cache(); 1101 } 1102 1103 // Discard all remembered set updates. 1104 JavaThread::dirty_card_queue_set().abandon_logs(); 1105 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty"); 1106 } 1107 1108 void G1CollectedHeap::verify_after_full_collection() { 1109 check_gc_time_stamps(); 1110 _hrm.verify_optional(); 1111 _verifier->verify_region_sets_optional(); 1112 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull); 1113 // Clear the previous marking bitmap, if needed for bitmap verification. 1114 // Note we cannot do this when we clear the next marking bitmap in 1115 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the 1116 // objects marked during a full GC against the previous bitmap. 1117 // But we need to clear it before calling check_bitmaps below since 1118 // the full GC has compacted objects and updated TAMS but not updated 1119 // the prev bitmap. 1120 if (G1VerifyBitmaps) { 1121 GCTraceTime(Debug, gc)("Clear Bitmap for Verification"); 1122 _cm->clear_prev_bitmap(workers()); 1123 } 1124 _verifier->check_bitmaps("Full GC End"); 1125 1126 // At this point there should be no regions in the 1127 // entire heap tagged as young. 1128 assert(check_young_list_empty(), "young list should be empty at this point"); 1129 1130 // Note: since we've just done a full GC, concurrent 1131 // marking is no longer active. Therefore we need not 1132 // re-enable reference discovery for the CM ref processor. 1133 // That will be done at the start of the next marking cycle. 1134 // We also know that the STW processor should no longer 1135 // discover any new references. 1136 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 1137 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition"); 1138 ref_processor_stw()->verify_no_references_recorded(); 1139 ref_processor_cm()->verify_no_references_recorded(); 1140 } 1141 1142 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) { 1143 // Post collection logging. 1144 // We should do this after we potentially resize the heap so 1145 // that all the COMMIT / UNCOMMIT events are generated before 1146 // the compaction events. 1147 print_hrm_post_compaction(); 1148 heap_transition->print(); 1149 print_heap_after_gc(); 1150 print_heap_regions(); 1151 #ifdef TRACESPINNING 1152 ParallelTaskTerminator::print_termination_counts(); 1153 #endif 1154 } 1155 1156 bool G1CollectedHeap::do_full_collection(bool explicit_gc, 1157 bool clear_all_soft_refs) { 1158 assert_at_safepoint_on_vm_thread(); 1159 1160 if (GCLocker::check_active_before_gc()) { 1161 // Full GC was not completed. 1162 return false; 1163 } 1164 1165 const bool do_clear_all_soft_refs = clear_all_soft_refs || 1166 soft_ref_policy()->should_clear_all_soft_refs(); 1167 1168 G1FullCollector collector(this, &_full_gc_memory_manager, explicit_gc, do_clear_all_soft_refs); 1169 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true); 1170 1171 collector.prepare_collection(); 1172 collector.collect(); 1173 collector.complete_collection(); 1174 1175 // Full collection was successfully completed. 1176 return true; 1177 } 1178 1179 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) { 1180 // Currently, there is no facility in the do_full_collection(bool) API to notify 1181 // the caller that the collection did not succeed (e.g., because it was locked 1182 // out by the GC locker). So, right now, we'll ignore the return value. 1183 bool dummy = do_full_collection(true, /* explicit_gc */ 1184 clear_all_soft_refs); 1185 } 1186 1187 void G1CollectedHeap::resize_if_necessary_after_full_collection() { 1188 // Capacity, free and used after the GC counted as full regions to 1189 // include the waste in the following calculations. 1190 const size_t capacity_after_gc = capacity(); 1191 const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes(); 1192 1193 // This is enforced in arguments.cpp. 1194 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, 1195 "otherwise the code below doesn't make sense"); 1196 1197 // We don't have floating point command-line arguments 1198 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0; 1199 const double maximum_used_percentage = 1.0 - minimum_free_percentage; 1200 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0; 1201 const double minimum_used_percentage = 1.0 - maximum_free_percentage; 1202 1203 const size_t min_heap_size = collector_policy()->min_heap_byte_size(); 1204 const size_t max_heap_size = collector_policy()->max_heap_byte_size(); 1205 1206 // We have to be careful here as these two calculations can overflow 1207 // 32-bit size_t's. 1208 double used_after_gc_d = (double) used_after_gc; 1209 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage; 1210 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage; 1211 1212 // Let's make sure that they are both under the max heap size, which 1213 // by default will make them fit into a size_t. 1214 double desired_capacity_upper_bound = (double) max_heap_size; 1215 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d, 1216 desired_capacity_upper_bound); 1217 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d, 1218 desired_capacity_upper_bound); 1219 1220 // We can now safely turn them into size_t's. 1221 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d; 1222 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d; 1223 1224 // This assert only makes sense here, before we adjust them 1225 // with respect to the min and max heap size. 1226 assert(minimum_desired_capacity <= maximum_desired_capacity, 1227 "minimum_desired_capacity = " SIZE_FORMAT ", " 1228 "maximum_desired_capacity = " SIZE_FORMAT, 1229 minimum_desired_capacity, maximum_desired_capacity); 1230 1231 // Should not be greater than the heap max size. No need to adjust 1232 // it with respect to the heap min size as it's a lower bound (i.e., 1233 // we'll try to make the capacity larger than it, not smaller). 1234 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size); 1235 // Should not be less than the heap min size. No need to adjust it 1236 // with respect to the heap max size as it's an upper bound (i.e., 1237 // we'll try to make the capacity smaller than it, not greater). 1238 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size); 1239 1240 if (capacity_after_gc < minimum_desired_capacity) { 1241 // Don't expand unless it's significant 1242 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc; 1243 1244 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). " 1245 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B " 1246 "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)", 1247 capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio); 1248 1249 expand(expand_bytes, _workers); 1250 1251 // No expansion, now see if we want to shrink 1252 } else if (capacity_after_gc > maximum_desired_capacity) { 1253 // Capacity too large, compute shrinking size 1254 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity; 1255 1256 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). " 1257 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B " 1258 "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)", 1259 capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio); 1260 1261 shrink(shrink_bytes); 1262 } 1263 } 1264 1265 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size, 1266 bool do_gc, 1267 bool clear_all_soft_refs, 1268 bool expect_null_mutator_alloc_region, 1269 bool* gc_succeeded) { 1270 *gc_succeeded = true; 1271 // Let's attempt the allocation first. 1272 HeapWord* result = 1273 attempt_allocation_at_safepoint(word_size, 1274 expect_null_mutator_alloc_region); 1275 if (result != NULL) { 1276 return result; 1277 } 1278 1279 // In a G1 heap, we're supposed to keep allocation from failing by 1280 // incremental pauses. Therefore, at least for now, we'll favor 1281 // expansion over collection. (This might change in the future if we can 1282 // do something smarter than full collection to satisfy a failed alloc.) 1283 result = expand_and_allocate(word_size); 1284 if (result != NULL) { 1285 return result; 1286 } 1287 1288 if (do_gc) { 1289 // Expansion didn't work, we'll try to do a Full GC. 1290 *gc_succeeded = do_full_collection(false, /* explicit_gc */ 1291 clear_all_soft_refs); 1292 } 1293 1294 return NULL; 1295 } 1296 1297 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size, 1298 bool* succeeded) { 1299 assert_at_safepoint_on_vm_thread(); 1300 1301 // Attempts to allocate followed by Full GC. 1302 HeapWord* result = 1303 satisfy_failed_allocation_helper(word_size, 1304 true, /* do_gc */ 1305 false, /* clear_all_soft_refs */ 1306 false, /* expect_null_mutator_alloc_region */ 1307 succeeded); 1308 1309 if (result != NULL || !*succeeded) { 1310 return result; 1311 } 1312 1313 // Attempts to allocate followed by Full GC that will collect all soft references. 1314 result = satisfy_failed_allocation_helper(word_size, 1315 true, /* do_gc */ 1316 true, /* clear_all_soft_refs */ 1317 true, /* expect_null_mutator_alloc_region */ 1318 succeeded); 1319 1320 if (result != NULL || !*succeeded) { 1321 return result; 1322 } 1323 1324 // Attempts to allocate, no GC 1325 result = satisfy_failed_allocation_helper(word_size, 1326 false, /* do_gc */ 1327 false, /* clear_all_soft_refs */ 1328 true, /* expect_null_mutator_alloc_region */ 1329 succeeded); 1330 1331 if (result != NULL) { 1332 return result; 1333 } 1334 1335 assert(!soft_ref_policy()->should_clear_all_soft_refs(), 1336 "Flag should have been handled and cleared prior to this point"); 1337 1338 // What else? We might try synchronous finalization later. If the total 1339 // space available is large enough for the allocation, then a more 1340 // complete compaction phase than we've tried so far might be 1341 // appropriate. 1342 return NULL; 1343 } 1344 1345 // Attempting to expand the heap sufficiently 1346 // to support an allocation of the given "word_size". If 1347 // successful, perform the allocation and return the address of the 1348 // allocated block, or else "NULL". 1349 1350 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) { 1351 assert_at_safepoint_on_vm_thread(); 1352 1353 _verifier->verify_region_sets_optional(); 1354 1355 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes); 1356 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B", 1357 word_size * HeapWordSize); 1358 1359 1360 if (expand(expand_bytes, _workers)) { 1361 _hrm.verify_optional(); 1362 _verifier->verify_region_sets_optional(); 1363 return attempt_allocation_at_safepoint(word_size, 1364 false /* expect_null_mutator_alloc_region */); 1365 } 1366 return NULL; 1367 } 1368 1369 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) { 1370 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); 1371 aligned_expand_bytes = align_up(aligned_expand_bytes, 1372 HeapRegion::GrainBytes); 1373 1374 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B", 1375 expand_bytes, aligned_expand_bytes); 1376 1377 if (is_maximal_no_gc()) { 1378 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)"); 1379 return false; 1380 } 1381 1382 double expand_heap_start_time_sec = os::elapsedTime(); 1383 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes); 1384 assert(regions_to_expand > 0, "Must expand by at least one region"); 1385 1386 uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers); 1387 if (expand_time_ms != NULL) { 1388 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS; 1389 } 1390 1391 if (expanded_by > 0) { 1392 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes; 1393 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition"); 1394 g1_policy()->record_new_heap_size(num_regions()); 1395 } else { 1396 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)"); 1397 1398 // The expansion of the virtual storage space was unsuccessful. 1399 // Let's see if it was because we ran out of swap. 1400 if (G1ExitOnExpansionFailure && 1401 _hrm.available() >= regions_to_expand) { 1402 // We had head room... 1403 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion"); 1404 } 1405 } 1406 return regions_to_expand > 0; 1407 } 1408 1409 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) { 1410 size_t aligned_shrink_bytes = 1411 ReservedSpace::page_align_size_down(shrink_bytes); 1412 aligned_shrink_bytes = align_down(aligned_shrink_bytes, 1413 HeapRegion::GrainBytes); 1414 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes); 1415 1416 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove); 1417 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes; 1418 1419 1420 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", 1421 shrink_bytes, aligned_shrink_bytes, shrunk_bytes); 1422 if (num_regions_removed > 0) { 1423 g1_policy()->record_new_heap_size(num_regions()); 1424 } else { 1425 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)"); 1426 } 1427 } 1428 1429 void G1CollectedHeap::shrink(size_t shrink_bytes) { 1430 _verifier->verify_region_sets_optional(); 1431 1432 // We should only reach here at the end of a Full GC which means we 1433 // should not not be holding to any GC alloc regions. The method 1434 // below will make sure of that and do any remaining clean up. 1435 _allocator->abandon_gc_alloc_regions(); 1436 1437 // Instead of tearing down / rebuilding the free lists here, we 1438 // could instead use the remove_all_pending() method on free_list to 1439 // remove only the ones that we need to remove. 1440 tear_down_region_sets(true /* free_list_only */); 1441 shrink_helper(shrink_bytes); 1442 rebuild_region_sets(true /* free_list_only */); 1443 1444 _hrm.verify_optional(); 1445 _verifier->verify_region_sets_optional(); 1446 } 1447 1448 // Public methods. 1449 1450 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) : 1451 CollectedHeap(), 1452 _young_gen_sampling_thread(NULL), 1453 _collector_policy(collector_policy), 1454 _soft_ref_policy(), 1455 _card_table(NULL), 1456 _memory_manager("G1 Young Generation", "end of minor GC"), 1457 _full_gc_memory_manager("G1 Old Generation", "end of major GC"), 1458 _eden_pool(NULL), 1459 _survivor_pool(NULL), 1460 _old_pool(NULL), 1461 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()), 1462 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()), 1463 _g1_policy(new G1DefaultPolicy(_gc_timer_stw)), 1464 _collection_set(this, _g1_policy), 1465 _dirty_card_queue_set(false), 1466 _is_alive_closure_cm(this), 1467 _is_alive_closure_stw(this), 1468 _ref_processor_cm(NULL), 1469 _ref_processor_stw(NULL), 1470 _bot(NULL), 1471 _hot_card_cache(NULL), 1472 _g1_rem_set(NULL), 1473 _cr(NULL), 1474 _g1mm(NULL), 1475 _preserved_marks_set(true /* in_c_heap */), 1476 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()), 1477 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()), 1478 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()), 1479 _humongous_reclaim_candidates(), 1480 _has_humongous_reclaim_candidates(false), 1481 _archive_allocator(NULL), 1482 _free_regions_coming(false), 1483 _gc_time_stamp(0), 1484 _summary_bytes_used(0), 1485 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight), 1486 _old_evac_stats("Old", OldPLABSize, PLABWeight), 1487 _expand_heap_after_alloc_failure(true), 1488 _old_marking_cycles_started(0), 1489 _old_marking_cycles_completed(0), 1490 _in_cset_fast_test() { 1491 1492 _workers = new WorkGang("GC Thread", ParallelGCThreads, 1493 /* are_GC_task_threads */true, 1494 /* are_ConcurrentGC_threads */false); 1495 _workers->initialize_workers(); 1496 _verifier = new G1HeapVerifier(this); 1497 1498 _allocator = new G1DefaultAllocator(this); 1499 1500 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics()); 1501 1502 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords); 1503 1504 // Override the default _filler_array_max_size so that no humongous filler 1505 // objects are created. 1506 _filler_array_max_size = _humongous_object_threshold_in_words; 1507 1508 uint n_queues = ParallelGCThreads; 1509 _task_queues = new RefToScanQueueSet(n_queues); 1510 1511 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC); 1512 1513 for (uint i = 0; i < n_queues; i++) { 1514 RefToScanQueue* q = new RefToScanQueue(); 1515 q->initialize(); 1516 _task_queues->register_queue(i, q); 1517 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo(); 1518 } 1519 1520 // Initialize the G1EvacuationFailureALot counters and flags. 1521 NOT_PRODUCT(reset_evacuation_should_fail();) 1522 1523 guarantee(_task_queues != NULL, "task_queues allocation failure."); 1524 } 1525 1526 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description, 1527 size_t size, 1528 size_t translation_factor) { 1529 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1); 1530 // Allocate a new reserved space, preferring to use large pages. 1531 ReservedSpace rs(size, preferred_page_size); 1532 G1RegionToSpaceMapper* result = 1533 G1RegionToSpaceMapper::create_mapper(rs, 1534 size, 1535 rs.alignment(), 1536 HeapRegion::GrainBytes, 1537 translation_factor, 1538 mtGC); 1539 1540 os::trace_page_sizes_for_requested_size(description, 1541 size, 1542 preferred_page_size, 1543 rs.alignment(), 1544 rs.base(), 1545 rs.size()); 1546 1547 return result; 1548 } 1549 1550 jint G1CollectedHeap::initialize_concurrent_refinement() { 1551 jint ecode = JNI_OK; 1552 _cr = G1ConcurrentRefine::create(&ecode); 1553 return ecode; 1554 } 1555 1556 jint G1CollectedHeap::initialize_young_gen_sampling_thread() { 1557 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread(); 1558 if (_young_gen_sampling_thread->osthread() == NULL) { 1559 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread"); 1560 return JNI_ENOMEM; 1561 } 1562 return JNI_OK; 1563 } 1564 1565 jint G1CollectedHeap::initialize() { 1566 os::enable_vtime(); 1567 1568 // Necessary to satisfy locking discipline assertions. 1569 1570 MutexLocker x(Heap_lock); 1571 1572 // While there are no constraints in the GC code that HeapWordSize 1573 // be any particular value, there are multiple other areas in the 1574 // system which believe this to be true (e.g. oop->object_size in some 1575 // cases incorrectly returns the size in wordSize units rather than 1576 // HeapWordSize). 1577 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 1578 1579 size_t init_byte_size = collector_policy()->initial_heap_byte_size(); 1580 size_t max_byte_size = collector_policy()->max_heap_byte_size(); 1581 size_t heap_alignment = collector_policy()->heap_alignment(); 1582 1583 // Ensure that the sizes are properly aligned. 1584 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1585 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1586 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap"); 1587 1588 // Reserve the maximum. 1589 1590 // When compressed oops are enabled, the preferred heap base 1591 // is calculated by subtracting the requested size from the 1592 // 32Gb boundary and using the result as the base address for 1593 // heap reservation. If the requested size is not aligned to 1594 // HeapRegion::GrainBytes (i.e. the alignment that is passed 1595 // into the ReservedHeapSpace constructor) then the actual 1596 // base of the reserved heap may end up differing from the 1597 // address that was requested (i.e. the preferred heap base). 1598 // If this happens then we could end up using a non-optimal 1599 // compressed oops mode. 1600 1601 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size, 1602 heap_alignment); 1603 1604 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size())); 1605 1606 // Create the barrier set for the entire reserved region. 1607 G1CardTable* ct = new G1CardTable(reserved_region()); 1608 ct->initialize(); 1609 G1SATBCardTableLoggingModRefBS* bs = new G1SATBCardTableLoggingModRefBS(ct); 1610 bs->initialize(); 1611 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity"); 1612 set_barrier_set(bs); 1613 _card_table = ct; 1614 1615 // Create the hot card cache. 1616 _hot_card_cache = new G1HotCardCache(this); 1617 1618 // Carve out the G1 part of the heap. 1619 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size); 1620 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size(); 1621 G1RegionToSpaceMapper* heap_storage = 1622 G1RegionToSpaceMapper::create_mapper(g1_rs, 1623 g1_rs.size(), 1624 page_size, 1625 HeapRegion::GrainBytes, 1626 1, 1627 mtJavaHeap); 1628 os::trace_page_sizes("Heap", 1629 collector_policy()->min_heap_byte_size(), 1630 max_byte_size, 1631 page_size, 1632 heap_rs.base(), 1633 heap_rs.size()); 1634 heap_storage->set_mapping_changed_listener(&_listener); 1635 1636 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps. 1637 G1RegionToSpaceMapper* bot_storage = 1638 create_aux_memory_mapper("Block Offset Table", 1639 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize), 1640 G1BlockOffsetTable::heap_map_factor()); 1641 1642 G1RegionToSpaceMapper* cardtable_storage = 1643 create_aux_memory_mapper("Card Table", 1644 G1CardTable::compute_size(g1_rs.size() / HeapWordSize), 1645 G1CardTable::heap_map_factor()); 1646 1647 G1RegionToSpaceMapper* card_counts_storage = 1648 create_aux_memory_mapper("Card Counts Table", 1649 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize), 1650 G1CardCounts::heap_map_factor()); 1651 1652 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size()); 1653 G1RegionToSpaceMapper* prev_bitmap_storage = 1654 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1655 G1RegionToSpaceMapper* next_bitmap_storage = 1656 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1657 1658 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage); 1659 _card_table->initialize(cardtable_storage); 1660 // Do later initialization work for concurrent refinement. 1661 _hot_card_cache->initialize(card_counts_storage); 1662 1663 // 6843694 - ensure that the maximum region index can fit 1664 // in the remembered set structures. 1665 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; 1666 guarantee((max_regions() - 1) <= max_region_idx, "too many regions"); 1667 1668 // Also create a G1 rem set. 1669 _g1_rem_set = new G1RemSet(this, _card_table, _hot_card_cache); 1670 _g1_rem_set->initialize(max_capacity(), max_regions()); 1671 1672 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; 1673 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); 1674 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region, 1675 "too many cards per region"); 1676 1677 FreeRegionList::set_unrealistically_long_length(max_regions() + 1); 1678 1679 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage); 1680 1681 { 1682 HeapWord* start = _hrm.reserved().start(); 1683 HeapWord* end = _hrm.reserved().end(); 1684 size_t granularity = HeapRegion::GrainBytes; 1685 1686 _in_cset_fast_test.initialize(start, end, granularity); 1687 _humongous_reclaim_candidates.initialize(start, end, granularity); 1688 } 1689 1690 // Create the G1ConcurrentMark data structure and thread. 1691 // (Must do this late, so that "max_regions" is defined.) 1692 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage); 1693 if (_cm == NULL || !_cm->completed_initialization()) { 1694 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark"); 1695 return JNI_ENOMEM; 1696 } 1697 _cmThread = _cm->cm_thread(); 1698 1699 // Now expand into the initial heap size. 1700 if (!expand(init_byte_size, _workers)) { 1701 vm_shutdown_during_initialization("Failed to allocate initial heap."); 1702 return JNI_ENOMEM; 1703 } 1704 1705 // Perform any initialization actions delegated to the policy. 1706 g1_policy()->init(this, &_collection_set); 1707 1708 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon, 1709 SATB_Q_FL_lock, 1710 G1SATBProcessCompletedThreshold, 1711 Shared_SATB_Q_lock); 1712 1713 jint ecode = initialize_concurrent_refinement(); 1714 if (ecode != JNI_OK) { 1715 return ecode; 1716 } 1717 1718 ecode = initialize_young_gen_sampling_thread(); 1719 if (ecode != JNI_OK) { 1720 return ecode; 1721 } 1722 1723 JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon, 1724 DirtyCardQ_FL_lock, 1725 (int)concurrent_refine()->yellow_zone(), 1726 (int)concurrent_refine()->red_zone(), 1727 Shared_DirtyCardQ_lock, 1728 NULL, // fl_owner 1729 true); // init_free_ids 1730 1731 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon, 1732 DirtyCardQ_FL_lock, 1733 -1, // never trigger processing 1734 -1, // no limit on length 1735 Shared_DirtyCardQ_lock, 1736 &JavaThread::dirty_card_queue_set()); 1737 1738 // Here we allocate the dummy HeapRegion that is required by the 1739 // G1AllocRegion class. 1740 HeapRegion* dummy_region = _hrm.get_dummy_region(); 1741 1742 // We'll re-use the same region whether the alloc region will 1743 // require BOT updates or not and, if it doesn't, then a non-young 1744 // region will complain that it cannot support allocations without 1745 // BOT updates. So we'll tag the dummy region as eden to avoid that. 1746 dummy_region->set_eden(); 1747 // Make sure it's full. 1748 dummy_region->set_top(dummy_region->end()); 1749 G1AllocRegion::setup(this, dummy_region); 1750 1751 _allocator->init_mutator_alloc_region(); 1752 1753 // Do create of the monitoring and management support so that 1754 // values in the heap have been properly initialized. 1755 _g1mm = new G1MonitoringSupport(this); 1756 1757 G1StringDedup::initialize(); 1758 1759 _preserved_marks_set.init(ParallelGCThreads); 1760 1761 _collection_set.initialize(max_regions()); 1762 1763 return JNI_OK; 1764 } 1765 1766 void G1CollectedHeap::initialize_serviceability() { 1767 _eden_pool = new G1EdenPool(this); 1768 _survivor_pool = new G1SurvivorPool(this); 1769 _old_pool = new G1OldGenPool(this); 1770 1771 _full_gc_memory_manager.add_pool(_eden_pool); 1772 _full_gc_memory_manager.add_pool(_survivor_pool); 1773 _full_gc_memory_manager.add_pool(_old_pool); 1774 1775 _memory_manager.add_pool(_eden_pool); 1776 _memory_manager.add_pool(_survivor_pool); 1777 1778 } 1779 1780 void G1CollectedHeap::stop() { 1781 // Stop all concurrent threads. We do this to make sure these threads 1782 // do not continue to execute and access resources (e.g. logging) 1783 // that are destroyed during shutdown. 1784 _cr->stop(); 1785 _young_gen_sampling_thread->stop(); 1786 _cmThread->stop(); 1787 if (G1StringDedup::is_enabled()) { 1788 G1StringDedup::stop(); 1789 } 1790 } 1791 1792 void G1CollectedHeap::safepoint_synchronize_begin() { 1793 SuspendibleThreadSet::synchronize(); 1794 } 1795 1796 void G1CollectedHeap::safepoint_synchronize_end() { 1797 SuspendibleThreadSet::desynchronize(); 1798 } 1799 1800 size_t G1CollectedHeap::conservative_max_heap_alignment() { 1801 return HeapRegion::max_region_size(); 1802 } 1803 1804 void G1CollectedHeap::post_initialize() { 1805 CollectedHeap::post_initialize(); 1806 ref_processing_init(); 1807 } 1808 1809 void G1CollectedHeap::ref_processing_init() { 1810 // Reference processing in G1 currently works as follows: 1811 // 1812 // * There are two reference processor instances. One is 1813 // used to record and process discovered references 1814 // during concurrent marking; the other is used to 1815 // record and process references during STW pauses 1816 // (both full and incremental). 1817 // * Both ref processors need to 'span' the entire heap as 1818 // the regions in the collection set may be dotted around. 1819 // 1820 // * For the concurrent marking ref processor: 1821 // * Reference discovery is enabled at initial marking. 1822 // * Reference discovery is disabled and the discovered 1823 // references processed etc during remarking. 1824 // * Reference discovery is MT (see below). 1825 // * Reference discovery requires a barrier (see below). 1826 // * Reference processing may or may not be MT 1827 // (depending on the value of ParallelRefProcEnabled 1828 // and ParallelGCThreads). 1829 // * A full GC disables reference discovery by the CM 1830 // ref processor and abandons any entries on it's 1831 // discovered lists. 1832 // 1833 // * For the STW processor: 1834 // * Non MT discovery is enabled at the start of a full GC. 1835 // * Processing and enqueueing during a full GC is non-MT. 1836 // * During a full GC, references are processed after marking. 1837 // 1838 // * Discovery (may or may not be MT) is enabled at the start 1839 // of an incremental evacuation pause. 1840 // * References are processed near the end of a STW evacuation pause. 1841 // * For both types of GC: 1842 // * Discovery is atomic - i.e. not concurrent. 1843 // * Reference discovery will not need a barrier. 1844 1845 MemRegion mr = reserved_region(); 1846 1847 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1); 1848 1849 // Concurrent Mark ref processor 1850 _ref_processor_cm = 1851 new ReferenceProcessor(mr, // span 1852 mt_processing, 1853 // mt processing 1854 ParallelGCThreads, 1855 // degree of mt processing 1856 (ParallelGCThreads > 1) || (ConcGCThreads > 1), 1857 // mt discovery 1858 MAX2(ParallelGCThreads, ConcGCThreads), 1859 // degree of mt discovery 1860 false, 1861 // Reference discovery is not atomic 1862 &_is_alive_closure_cm); 1863 // is alive closure 1864 // (for efficiency/performance) 1865 1866 // STW ref processor 1867 _ref_processor_stw = 1868 new ReferenceProcessor(mr, // span 1869 mt_processing, 1870 // mt processing 1871 ParallelGCThreads, 1872 // degree of mt processing 1873 (ParallelGCThreads > 1), 1874 // mt discovery 1875 ParallelGCThreads, 1876 // degree of mt discovery 1877 true, 1878 // Reference discovery is atomic 1879 &_is_alive_closure_stw); 1880 // is alive closure 1881 // (for efficiency/performance) 1882 } 1883 1884 CollectorPolicy* G1CollectedHeap::collector_policy() const { 1885 return _collector_policy; 1886 } 1887 1888 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() { 1889 return &_soft_ref_policy; 1890 } 1891 1892 size_t G1CollectedHeap::capacity() const { 1893 return _hrm.length() * HeapRegion::GrainBytes; 1894 } 1895 1896 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const { 1897 return _hrm.total_free_bytes(); 1898 } 1899 1900 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) { 1901 hr->reset_gc_time_stamp(); 1902 } 1903 1904 #ifndef PRODUCT 1905 1906 class CheckGCTimeStampsHRClosure : public HeapRegionClosure { 1907 private: 1908 unsigned _gc_time_stamp; 1909 bool _failures; 1910 1911 public: 1912 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) : 1913 _gc_time_stamp(gc_time_stamp), _failures(false) { } 1914 1915 virtual bool do_heap_region(HeapRegion* hr) { 1916 unsigned region_gc_time_stamp = hr->get_gc_time_stamp(); 1917 if (_gc_time_stamp != region_gc_time_stamp) { 1918 log_error(gc, verify)("Region " HR_FORMAT " has GC time stamp = %d, expected %d", HR_FORMAT_PARAMS(hr), 1919 region_gc_time_stamp, _gc_time_stamp); 1920 _failures = true; 1921 } 1922 return false; 1923 } 1924 1925 bool failures() { return _failures; } 1926 }; 1927 1928 void G1CollectedHeap::check_gc_time_stamps() { 1929 CheckGCTimeStampsHRClosure cl(_gc_time_stamp); 1930 heap_region_iterate(&cl); 1931 guarantee(!cl.failures(), "all GC time stamps should have been reset"); 1932 } 1933 #endif // PRODUCT 1934 1935 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) { 1936 _hot_card_cache->drain(cl, worker_i); 1937 } 1938 1939 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) { 1940 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 1941 size_t n_completed_buffers = 0; 1942 while (dcqs.apply_closure_during_gc(cl, worker_i)) { 1943 n_completed_buffers++; 1944 } 1945 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers); 1946 dcqs.clear_n_completed_buffers(); 1947 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!"); 1948 } 1949 1950 // Computes the sum of the storage used by the various regions. 1951 size_t G1CollectedHeap::used() const { 1952 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions(); 1953 if (_archive_allocator != NULL) { 1954 result += _archive_allocator->used(); 1955 } 1956 return result; 1957 } 1958 1959 size_t G1CollectedHeap::used_unlocked() const { 1960 return _summary_bytes_used; 1961 } 1962 1963 class SumUsedClosure: public HeapRegionClosure { 1964 size_t _used; 1965 public: 1966 SumUsedClosure() : _used(0) {} 1967 bool do_heap_region(HeapRegion* r) { 1968 _used += r->used(); 1969 return false; 1970 } 1971 size_t result() { return _used; } 1972 }; 1973 1974 size_t G1CollectedHeap::recalculate_used() const { 1975 double recalculate_used_start = os::elapsedTime(); 1976 1977 SumUsedClosure blk; 1978 heap_region_iterate(&blk); 1979 1980 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0); 1981 return blk.result(); 1982 } 1983 1984 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) { 1985 switch (cause) { 1986 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent; 1987 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent; 1988 case GCCause::_wb_conc_mark: return true; 1989 default : return false; 1990 } 1991 } 1992 1993 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 1994 switch (cause) { 1995 case GCCause::_gc_locker: return GCLockerInvokesConcurrent; 1996 case GCCause::_g1_humongous_allocation: return true; 1997 default: return is_user_requested_concurrent_full_gc(cause); 1998 } 1999 } 2000 2001 #ifndef PRODUCT 2002 void G1CollectedHeap::allocate_dummy_regions() { 2003 // Let's fill up most of the region 2004 size_t word_size = HeapRegion::GrainWords - 1024; 2005 // And as a result the region we'll allocate will be humongous. 2006 guarantee(is_humongous(word_size), "sanity"); 2007 2008 // _filler_array_max_size is set to humongous object threshold 2009 // but temporarily change it to use CollectedHeap::fill_with_object(). 2010 SizeTFlagSetting fs(_filler_array_max_size, word_size); 2011 2012 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) { 2013 // Let's use the existing mechanism for the allocation 2014 HeapWord* dummy_obj = humongous_obj_allocate(word_size); 2015 if (dummy_obj != NULL) { 2016 MemRegion mr(dummy_obj, word_size); 2017 CollectedHeap::fill_with_object(mr); 2018 } else { 2019 // If we can't allocate once, we probably cannot allocate 2020 // again. Let's get out of the loop. 2021 break; 2022 } 2023 } 2024 } 2025 #endif // !PRODUCT 2026 2027 void G1CollectedHeap::increment_old_marking_cycles_started() { 2028 assert(_old_marking_cycles_started == _old_marking_cycles_completed || 2029 _old_marking_cycles_started == _old_marking_cycles_completed + 1, 2030 "Wrong marking cycle count (started: %d, completed: %d)", 2031 _old_marking_cycles_started, _old_marking_cycles_completed); 2032 2033 _old_marking_cycles_started++; 2034 } 2035 2036 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) { 2037 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 2038 2039 // We assume that if concurrent == true, then the caller is a 2040 // concurrent thread that was joined the Suspendible Thread 2041 // Set. If there's ever a cheap way to check this, we should add an 2042 // assert here. 2043 2044 // Given that this method is called at the end of a Full GC or of a 2045 // concurrent cycle, and those can be nested (i.e., a Full GC can 2046 // interrupt a concurrent cycle), the number of full collections 2047 // completed should be either one (in the case where there was no 2048 // nesting) or two (when a Full GC interrupted a concurrent cycle) 2049 // behind the number of full collections started. 2050 2051 // This is the case for the inner caller, i.e. a Full GC. 2052 assert(concurrent || 2053 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || 2054 (_old_marking_cycles_started == _old_marking_cycles_completed + 2), 2055 "for inner caller (Full GC): _old_marking_cycles_started = %u " 2056 "is inconsistent with _old_marking_cycles_completed = %u", 2057 _old_marking_cycles_started, _old_marking_cycles_completed); 2058 2059 // This is the case for the outer caller, i.e. the concurrent cycle. 2060 assert(!concurrent || 2061 (_old_marking_cycles_started == _old_marking_cycles_completed + 1), 2062 "for outer caller (concurrent cycle): " 2063 "_old_marking_cycles_started = %u " 2064 "is inconsistent with _old_marking_cycles_completed = %u", 2065 _old_marking_cycles_started, _old_marking_cycles_completed); 2066 2067 _old_marking_cycles_completed += 1; 2068 2069 // We need to clear the "in_progress" flag in the CM thread before 2070 // we wake up any waiters (especially when ExplicitInvokesConcurrent 2071 // is set) so that if a waiter requests another System.gc() it doesn't 2072 // incorrectly see that a marking cycle is still in progress. 2073 if (concurrent) { 2074 _cmThread->set_idle(); 2075 } 2076 2077 // This notify_all() will ensure that a thread that called 2078 // System.gc() with (with ExplicitGCInvokesConcurrent set or not) 2079 // and it's waiting for a full GC to finish will be woken up. It is 2080 // waiting in VM_G1CollectForAllocation::doit_epilogue(). 2081 FullGCCount_lock->notify_all(); 2082 } 2083 2084 void G1CollectedHeap::collect(GCCause::Cause cause) { 2085 assert_heap_not_locked(); 2086 2087 uint gc_count_before; 2088 uint old_marking_count_before; 2089 uint full_gc_count_before; 2090 bool retry_gc; 2091 2092 do { 2093 retry_gc = false; 2094 2095 { 2096 MutexLocker ml(Heap_lock); 2097 2098 // Read the GC count while holding the Heap_lock 2099 gc_count_before = total_collections(); 2100 full_gc_count_before = total_full_collections(); 2101 old_marking_count_before = _old_marking_cycles_started; 2102 } 2103 2104 if (should_do_concurrent_full_gc(cause)) { 2105 // Schedule an initial-mark evacuation pause that will start a 2106 // concurrent cycle. We're setting word_size to 0 which means that 2107 // we are not requesting a post-GC allocation. 2108 VM_G1CollectForAllocation op(0, /* word_size */ 2109 gc_count_before, 2110 cause, 2111 true, /* should_initiate_conc_mark */ 2112 g1_policy()->max_pause_time_ms()); 2113 VMThread::execute(&op); 2114 if (!op.pause_succeeded()) { 2115 if (old_marking_count_before == _old_marking_cycles_started) { 2116 retry_gc = op.should_retry_gc(); 2117 } else { 2118 // A Full GC happened while we were trying to schedule the 2119 // initial-mark GC. No point in starting a new cycle given 2120 // that the whole heap was collected anyway. 2121 } 2122 2123 if (retry_gc) { 2124 if (GCLocker::is_active_and_needs_gc()) { 2125 GCLocker::stall_until_clear(); 2126 } 2127 } 2128 } 2129 } else { 2130 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc 2131 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { 2132 2133 // Schedule a standard evacuation pause. We're setting word_size 2134 // to 0 which means that we are not requesting a post-GC allocation. 2135 VM_G1CollectForAllocation op(0, /* word_size */ 2136 gc_count_before, 2137 cause, 2138 false, /* should_initiate_conc_mark */ 2139 g1_policy()->max_pause_time_ms()); 2140 VMThread::execute(&op); 2141 } else { 2142 // Schedule a Full GC. 2143 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause); 2144 VMThread::execute(&op); 2145 } 2146 } 2147 } while (retry_gc); 2148 } 2149 2150 bool G1CollectedHeap::is_in(const void* p) const { 2151 if (_hrm.reserved().contains(p)) { 2152 // Given that we know that p is in the reserved space, 2153 // heap_region_containing() should successfully 2154 // return the containing region. 2155 HeapRegion* hr = heap_region_containing(p); 2156 return hr->is_in(p); 2157 } else { 2158 return false; 2159 } 2160 } 2161 2162 #ifdef ASSERT 2163 bool G1CollectedHeap::is_in_exact(const void* p) const { 2164 bool contains = reserved_region().contains(p); 2165 bool available = _hrm.is_available(addr_to_region((HeapWord*)p)); 2166 if (contains && available) { 2167 return true; 2168 } else { 2169 return false; 2170 } 2171 } 2172 #endif 2173 2174 // Iteration functions. 2175 2176 // Iterates an ObjectClosure over all objects within a HeapRegion. 2177 2178 class IterateObjectClosureRegionClosure: public HeapRegionClosure { 2179 ObjectClosure* _cl; 2180 public: 2181 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} 2182 bool do_heap_region(HeapRegion* r) { 2183 if (!r->is_continues_humongous()) { 2184 r->object_iterate(_cl); 2185 } 2186 return false; 2187 } 2188 }; 2189 2190 void G1CollectedHeap::object_iterate(ObjectClosure* cl) { 2191 IterateObjectClosureRegionClosure blk(cl); 2192 heap_region_iterate(&blk); 2193 } 2194 2195 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { 2196 _hrm.iterate(cl); 2197 } 2198 2199 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl, 2200 HeapRegionClaimer *hrclaimer, 2201 uint worker_id) const { 2202 _hrm.par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id)); 2203 } 2204 2205 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl, 2206 HeapRegionClaimer *hrclaimer) const { 2207 _hrm.par_iterate(cl, hrclaimer, 0); 2208 } 2209 2210 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) { 2211 _collection_set.iterate(cl); 2212 } 2213 2214 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) { 2215 _collection_set.iterate_from(cl, worker_id, workers()->active_workers()); 2216 } 2217 2218 HeapWord* G1CollectedHeap::block_start(const void* addr) const { 2219 HeapRegion* hr = heap_region_containing(addr); 2220 return hr->block_start(addr); 2221 } 2222 2223 size_t G1CollectedHeap::block_size(const HeapWord* addr) const { 2224 HeapRegion* hr = heap_region_containing(addr); 2225 return hr->block_size(addr); 2226 } 2227 2228 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { 2229 HeapRegion* hr = heap_region_containing(addr); 2230 return hr->block_is_obj(addr); 2231 } 2232 2233 bool G1CollectedHeap::supports_tlab_allocation() const { 2234 return true; 2235 } 2236 2237 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { 2238 return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes; 2239 } 2240 2241 size_t G1CollectedHeap::tlab_used(Thread* ignored) const { 2242 return _eden.length() * HeapRegion::GrainBytes; 2243 } 2244 2245 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size 2246 // must be equal to the humongous object limit. 2247 size_t G1CollectedHeap::max_tlab_size() const { 2248 return align_down(_humongous_object_threshold_in_words, MinObjAlignment); 2249 } 2250 2251 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { 2252 return _allocator->unsafe_max_tlab_alloc(); 2253 } 2254 2255 size_t G1CollectedHeap::max_capacity() const { 2256 return _hrm.reserved().byte_size(); 2257 } 2258 2259 jlong G1CollectedHeap::millis_since_last_gc() { 2260 // See the notes in GenCollectedHeap::millis_since_last_gc() 2261 // for more information about the implementation. 2262 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) - 2263 _g1_policy->collection_pause_end_millis(); 2264 if (ret_val < 0) { 2265 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT 2266 ". returning zero instead.", ret_val); 2267 return 0; 2268 } 2269 return ret_val; 2270 } 2271 2272 void G1CollectedHeap::prepare_for_verify() { 2273 _verifier->prepare_for_verify(); 2274 } 2275 2276 void G1CollectedHeap::verify(VerifyOption vo) { 2277 _verifier->verify(vo); 2278 } 2279 2280 bool G1CollectedHeap::supports_concurrent_phase_control() const { 2281 return true; 2282 } 2283 2284 const char* const* G1CollectedHeap::concurrent_phases() const { 2285 return _cmThread->concurrent_phases(); 2286 } 2287 2288 bool G1CollectedHeap::request_concurrent_phase(const char* phase) { 2289 return _cmThread->request_concurrent_phase(phase); 2290 } 2291 2292 class PrintRegionClosure: public HeapRegionClosure { 2293 outputStream* _st; 2294 public: 2295 PrintRegionClosure(outputStream* st) : _st(st) {} 2296 bool do_heap_region(HeapRegion* r) { 2297 r->print_on(_st); 2298 return false; 2299 } 2300 }; 2301 2302 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2303 const HeapRegion* hr, 2304 const VerifyOption vo) const { 2305 switch (vo) { 2306 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); 2307 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); 2308 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr); 2309 default: ShouldNotReachHere(); 2310 } 2311 return false; // keep some compilers happy 2312 } 2313 2314 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2315 const VerifyOption vo) const { 2316 switch (vo) { 2317 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); 2318 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); 2319 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj); 2320 default: ShouldNotReachHere(); 2321 } 2322 return false; // keep some compilers happy 2323 } 2324 2325 void G1CollectedHeap::print_heap_regions() const { 2326 LogTarget(Trace, gc, heap, region) lt; 2327 if (lt.is_enabled()) { 2328 LogStream ls(lt); 2329 print_regions_on(&ls); 2330 } 2331 } 2332 2333 void G1CollectedHeap::print_on(outputStream* st) const { 2334 st->print(" %-20s", "garbage-first heap"); 2335 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 2336 capacity()/K, used_unlocked()/K); 2337 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")", 2338 p2i(_hrm.reserved().start()), 2339 p2i(_hrm.reserved().end())); 2340 st->cr(); 2341 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); 2342 uint young_regions = young_regions_count(); 2343 st->print("%u young (" SIZE_FORMAT "K), ", young_regions, 2344 (size_t) young_regions * HeapRegion::GrainBytes / K); 2345 uint survivor_regions = survivor_regions_count(); 2346 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, 2347 (size_t) survivor_regions * HeapRegion::GrainBytes / K); 2348 st->cr(); 2349 MetaspaceAux::print_on(st); 2350 } 2351 2352 void G1CollectedHeap::print_regions_on(outputStream* st) const { 2353 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, " 2354 "HS=humongous(starts), HC=humongous(continues), " 2355 "CS=collection set, F=free, A=archive, TS=gc time stamp, " 2356 "TAMS=top-at-mark-start (previous, next)"); 2357 PrintRegionClosure blk(st); 2358 heap_region_iterate(&blk); 2359 } 2360 2361 void G1CollectedHeap::print_extended_on(outputStream* st) const { 2362 print_on(st); 2363 2364 // Print the per-region information. 2365 print_regions_on(st); 2366 } 2367 2368 void G1CollectedHeap::print_on_error(outputStream* st) const { 2369 this->CollectedHeap::print_on_error(st); 2370 2371 if (_cm != NULL) { 2372 st->cr(); 2373 _cm->print_on_error(st); 2374 } 2375 } 2376 2377 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const { 2378 workers()->print_worker_threads_on(st); 2379 _cmThread->print_on(st); 2380 st->cr(); 2381 _cm->print_worker_threads_on(st); 2382 _cr->print_threads_on(st); 2383 _young_gen_sampling_thread->print_on(st); 2384 if (G1StringDedup::is_enabled()) { 2385 G1StringDedup::print_worker_threads_on(st); 2386 } 2387 } 2388 2389 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { 2390 workers()->threads_do(tc); 2391 tc->do_thread(_cmThread); 2392 _cm->threads_do(tc); 2393 _cr->threads_do(tc); 2394 tc->do_thread(_young_gen_sampling_thread); 2395 if (G1StringDedup::is_enabled()) { 2396 G1StringDedup::threads_do(tc); 2397 } 2398 } 2399 2400 void G1CollectedHeap::print_tracing_info() const { 2401 g1_rem_set()->print_summary_info(); 2402 concurrent_mark()->print_summary_info(); 2403 } 2404 2405 #ifndef PRODUCT 2406 // Helpful for debugging RSet issues. 2407 2408 class PrintRSetsClosure : public HeapRegionClosure { 2409 private: 2410 const char* _msg; 2411 size_t _occupied_sum; 2412 2413 public: 2414 bool do_heap_region(HeapRegion* r) { 2415 HeapRegionRemSet* hrrs = r->rem_set(); 2416 size_t occupied = hrrs->occupied(); 2417 _occupied_sum += occupied; 2418 2419 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r)); 2420 if (occupied == 0) { 2421 tty->print_cr(" RSet is empty"); 2422 } else { 2423 hrrs->print(); 2424 } 2425 tty->print_cr("----------"); 2426 return false; 2427 } 2428 2429 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { 2430 tty->cr(); 2431 tty->print_cr("========================================"); 2432 tty->print_cr("%s", msg); 2433 tty->cr(); 2434 } 2435 2436 ~PrintRSetsClosure() { 2437 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum); 2438 tty->print_cr("========================================"); 2439 tty->cr(); 2440 } 2441 }; 2442 2443 void G1CollectedHeap::print_cset_rsets() { 2444 PrintRSetsClosure cl("Printing CSet RSets"); 2445 collection_set_iterate(&cl); 2446 } 2447 2448 void G1CollectedHeap::print_all_rsets() { 2449 PrintRSetsClosure cl("Printing All RSets");; 2450 heap_region_iterate(&cl); 2451 } 2452 #endif // PRODUCT 2453 2454 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() { 2455 2456 size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes; 2457 size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes; 2458 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked(); 2459 2460 size_t eden_capacity_bytes = 2461 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes; 2462 2463 VirtualSpaceSummary heap_summary = create_heap_space_summary(); 2464 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes, 2465 eden_capacity_bytes, survivor_used_bytes, num_regions()); 2466 } 2467 2468 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) { 2469 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(), 2470 stats->unused(), stats->used(), stats->region_end_waste(), 2471 stats->regions_filled(), stats->direct_allocated(), 2472 stats->failure_used(), stats->failure_waste()); 2473 } 2474 2475 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) { 2476 const G1HeapSummary& heap_summary = create_g1_heap_summary(); 2477 gc_tracer->report_gc_heap_summary(when, heap_summary); 2478 2479 const MetaspaceSummary& metaspace_summary = create_metaspace_summary(); 2480 gc_tracer->report_metaspace_summary(when, metaspace_summary); 2481 } 2482 2483 G1CollectedHeap* G1CollectedHeap::heap() { 2484 CollectedHeap* heap = Universe::heap(); 2485 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()"); 2486 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap"); 2487 return (G1CollectedHeap*)heap; 2488 } 2489 2490 void G1CollectedHeap::gc_prologue(bool full) { 2491 // always_do_update_barrier = false; 2492 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 2493 2494 // This summary needs to be printed before incrementing total collections. 2495 g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections()); 2496 2497 // Update common counters. 2498 increment_total_collections(full /* full gc */); 2499 if (full) { 2500 increment_old_marking_cycles_started(); 2501 reset_gc_time_stamp(); 2502 } else { 2503 increment_gc_time_stamp(); 2504 } 2505 2506 // Fill TLAB's and such 2507 double start = os::elapsedTime(); 2508 accumulate_statistics_all_tlabs(); 2509 ensure_parsability(true); 2510 g1_policy()->phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0); 2511 } 2512 2513 void G1CollectedHeap::gc_epilogue(bool full) { 2514 // Update common counters. 2515 if (full) { 2516 // Update the number of full collections that have been completed. 2517 increment_old_marking_cycles_completed(false /* concurrent */); 2518 } 2519 2520 // We are at the end of the GC. Total collections has already been increased. 2521 g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1); 2522 2523 // FIXME: what is this about? 2524 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" 2525 // is set. 2526 #if COMPILER2_OR_JVMCI 2527 assert(DerivedPointerTable::is_empty(), "derived pointer present"); 2528 #endif 2529 // always_do_update_barrier = true; 2530 2531 double start = os::elapsedTime(); 2532 resize_all_tlabs(); 2533 g1_policy()->phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0); 2534 2535 MemoryService::track_memory_usage(); 2536 // We have just completed a GC. Update the soft reference 2537 // policy with the new heap occupancy 2538 Universe::update_heap_info_at_gc(); 2539 } 2540 2541 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, 2542 uint gc_count_before, 2543 bool* succeeded, 2544 GCCause::Cause gc_cause) { 2545 assert_heap_not_locked_and_not_at_safepoint(); 2546 VM_G1CollectForAllocation op(word_size, 2547 gc_count_before, 2548 gc_cause, 2549 false, /* should_initiate_conc_mark */ 2550 g1_policy()->max_pause_time_ms()); 2551 VMThread::execute(&op); 2552 2553 HeapWord* result = op.result(); 2554 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded(); 2555 assert(result == NULL || ret_succeeded, 2556 "the result should be NULL if the VM did not succeed"); 2557 *succeeded = ret_succeeded; 2558 2559 assert_heap_not_locked(); 2560 return result; 2561 } 2562 2563 void 2564 G1CollectedHeap::doConcurrentMark() { 2565 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); 2566 if (!_cmThread->in_progress()) { 2567 _cmThread->set_started(); 2568 CGC_lock->notify(); 2569 } 2570 } 2571 2572 size_t G1CollectedHeap::pending_card_num() { 2573 size_t extra_cards = 0; 2574 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *curr = jtiwh.next(); ) { 2575 DirtyCardQueue& dcq = curr->dirty_card_queue(); 2576 extra_cards += dcq.size(); 2577 } 2578 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 2579 size_t buffer_size = dcqs.buffer_size(); 2580 size_t buffer_num = dcqs.completed_buffers_num(); 2581 2582 return buffer_size * buffer_num + extra_cards; 2583 } 2584 2585 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const { 2586 // We don't nominate objects with many remembered set entries, on 2587 // the assumption that such objects are likely still live. 2588 HeapRegionRemSet* rem_set = r->rem_set(); 2589 2590 return G1EagerReclaimHumongousObjectsWithStaleRefs ? 2591 rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) : 2592 G1EagerReclaimHumongousObjects && rem_set->is_empty(); 2593 } 2594 2595 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure { 2596 private: 2597 size_t _total_humongous; 2598 size_t _candidate_humongous; 2599 2600 DirtyCardQueue _dcq; 2601 2602 bool humongous_region_is_candidate(G1CollectedHeap* g1h, HeapRegion* region) const { 2603 assert(region->is_starts_humongous(), "Must start a humongous object"); 2604 2605 oop obj = oop(region->bottom()); 2606 2607 // Dead objects cannot be eager reclaim candidates. Due to class 2608 // unloading it is unsafe to query their classes so we return early. 2609 if (g1h->is_obj_dead(obj, region)) { 2610 return false; 2611 } 2612 2613 // Candidate selection must satisfy the following constraints 2614 // while concurrent marking is in progress: 2615 // 2616 // * In order to maintain SATB invariants, an object must not be 2617 // reclaimed if it was allocated before the start of marking and 2618 // has not had its references scanned. Such an object must have 2619 // its references (including type metadata) scanned to ensure no 2620 // live objects are missed by the marking process. Objects 2621 // allocated after the start of concurrent marking don't need to 2622 // be scanned. 2623 // 2624 // * An object must not be reclaimed if it is on the concurrent 2625 // mark stack. Objects allocated after the start of concurrent 2626 // marking are never pushed on the mark stack. 2627 // 2628 // Nominating only objects allocated after the start of concurrent 2629 // marking is sufficient to meet both constraints. This may miss 2630 // some objects that satisfy the constraints, but the marking data 2631 // structures don't support efficiently performing the needed 2632 // additional tests or scrubbing of the mark stack. 2633 // 2634 // However, we presently only nominate is_typeArray() objects. 2635 // A humongous object containing references induces remembered 2636 // set entries on other regions. In order to reclaim such an 2637 // object, those remembered sets would need to be cleaned up. 2638 // 2639 // We also treat is_typeArray() objects specially, allowing them 2640 // to be reclaimed even if allocated before the start of 2641 // concurrent mark. For this we rely on mark stack insertion to 2642 // exclude is_typeArray() objects, preventing reclaiming an object 2643 // that is in the mark stack. We also rely on the metadata for 2644 // such objects to be built-in and so ensured to be kept live. 2645 // Frequent allocation and drop of large binary blobs is an 2646 // important use case for eager reclaim, and this special handling 2647 // may reduce needed headroom. 2648 2649 return obj->is_typeArray() && 2650 g1h->is_potential_eager_reclaim_candidate(region); 2651 } 2652 2653 public: 2654 RegisterHumongousWithInCSetFastTestClosure() 2655 : _total_humongous(0), 2656 _candidate_humongous(0), 2657 _dcq(&JavaThread::dirty_card_queue_set()) { 2658 } 2659 2660 virtual bool do_heap_region(HeapRegion* r) { 2661 if (!r->is_starts_humongous()) { 2662 return false; 2663 } 2664 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 2665 2666 bool is_candidate = humongous_region_is_candidate(g1h, r); 2667 uint rindex = r->hrm_index(); 2668 g1h->set_humongous_reclaim_candidate(rindex, is_candidate); 2669 if (is_candidate) { 2670 _candidate_humongous++; 2671 g1h->register_humongous_region_with_cset(rindex); 2672 // Is_candidate already filters out humongous object with large remembered sets. 2673 // If we have a humongous object with a few remembered sets, we simply flush these 2674 // remembered set entries into the DCQS. That will result in automatic 2675 // re-evaluation of their remembered set entries during the following evacuation 2676 // phase. 2677 if (!r->rem_set()->is_empty()) { 2678 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries), 2679 "Found a not-small remembered set here. This is inconsistent with previous assumptions."); 2680 G1CardTable* ct = g1h->card_table(); 2681 HeapRegionRemSetIterator hrrs(r->rem_set()); 2682 size_t card_index; 2683 while (hrrs.has_next(card_index)) { 2684 jbyte* card_ptr = (jbyte*)ct->byte_for_index(card_index); 2685 // The remembered set might contain references to already freed 2686 // regions. Filter out such entries to avoid failing card table 2687 // verification. 2688 if (g1h->is_in_closed_subset(ct->addr_for(card_ptr))) { 2689 if (*card_ptr != G1CardTable::dirty_card_val()) { 2690 *card_ptr = G1CardTable::dirty_card_val(); 2691 _dcq.enqueue(card_ptr); 2692 } 2693 } 2694 } 2695 assert(hrrs.n_yielded() == r->rem_set()->occupied(), 2696 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries", 2697 hrrs.n_yielded(), r->rem_set()->occupied()); 2698 r->rem_set()->clear_locked(); 2699 } 2700 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty."); 2701 } 2702 _total_humongous++; 2703 2704 return false; 2705 } 2706 2707 size_t total_humongous() const { return _total_humongous; } 2708 size_t candidate_humongous() const { return _candidate_humongous; } 2709 2710 void flush_rem_set_entries() { _dcq.flush(); } 2711 }; 2712 2713 void G1CollectedHeap::register_humongous_regions_with_cset() { 2714 if (!G1EagerReclaimHumongousObjects) { 2715 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0); 2716 return; 2717 } 2718 double time = os::elapsed_counter(); 2719 2720 // Collect reclaim candidate information and register candidates with cset. 2721 RegisterHumongousWithInCSetFastTestClosure cl; 2722 heap_region_iterate(&cl); 2723 2724 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0; 2725 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time, 2726 cl.total_humongous(), 2727 cl.candidate_humongous()); 2728 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0; 2729 2730 // Finally flush all remembered set entries to re-check into the global DCQS. 2731 cl.flush_rem_set_entries(); 2732 } 2733 2734 class VerifyRegionRemSetClosure : public HeapRegionClosure { 2735 public: 2736 bool do_heap_region(HeapRegion* hr) { 2737 if (!hr->is_archive() && !hr->is_continues_humongous()) { 2738 hr->verify_rem_set(); 2739 } 2740 return false; 2741 } 2742 }; 2743 2744 uint G1CollectedHeap::num_task_queues() const { 2745 return _task_queues->size(); 2746 } 2747 2748 #if TASKQUEUE_STATS 2749 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) { 2750 st->print_raw_cr("GC Task Stats"); 2751 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); 2752 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); 2753 } 2754 2755 void G1CollectedHeap::print_taskqueue_stats() const { 2756 if (!log_is_enabled(Trace, gc, task, stats)) { 2757 return; 2758 } 2759 Log(gc, task, stats) log; 2760 ResourceMark rm; 2761 LogStream ls(log.trace()); 2762 outputStream* st = &ls; 2763 2764 print_taskqueue_stats_hdr(st); 2765 2766 TaskQueueStats totals; 2767 const uint n = num_task_queues(); 2768 for (uint i = 0; i < n; ++i) { 2769 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr(); 2770 totals += task_queue(i)->stats; 2771 } 2772 st->print_raw("tot "); totals.print(st); st->cr(); 2773 2774 DEBUG_ONLY(totals.verify()); 2775 } 2776 2777 void G1CollectedHeap::reset_taskqueue_stats() { 2778 const uint n = num_task_queues(); 2779 for (uint i = 0; i < n; ++i) { 2780 task_queue(i)->stats.reset(); 2781 } 2782 } 2783 #endif // TASKQUEUE_STATS 2784 2785 void G1CollectedHeap::wait_for_root_region_scanning() { 2786 double scan_wait_start = os::elapsedTime(); 2787 // We have to wait until the CM threads finish scanning the 2788 // root regions as it's the only way to ensure that all the 2789 // objects on them have been correctly scanned before we start 2790 // moving them during the GC. 2791 bool waited = _cm->root_regions()->wait_until_scan_finished(); 2792 double wait_time_ms = 0.0; 2793 if (waited) { 2794 double scan_wait_end = os::elapsedTime(); 2795 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0; 2796 } 2797 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms); 2798 } 2799 2800 class G1PrintCollectionSetClosure : public HeapRegionClosure { 2801 private: 2802 G1HRPrinter* _hr_printer; 2803 public: 2804 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { } 2805 2806 virtual bool do_heap_region(HeapRegion* r) { 2807 _hr_printer->cset(r); 2808 return false; 2809 } 2810 }; 2811 2812 void G1CollectedHeap::start_new_collection_set() { 2813 collection_set()->start_incremental_building(); 2814 2815 clear_cset_fast_test(); 2816 2817 guarantee(_eden.length() == 0, "eden should have been cleared"); 2818 g1_policy()->transfer_survivors_to_cset(survivor()); 2819 } 2820 2821 bool 2822 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { 2823 assert_at_safepoint_on_vm_thread(); 2824 guarantee(!is_gc_active(), "collection is not reentrant"); 2825 2826 if (GCLocker::check_active_before_gc()) { 2827 return false; 2828 } 2829 2830 _gc_timer_stw->register_gc_start(); 2831 2832 GCIdMark gc_id_mark; 2833 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start()); 2834 2835 SvcGCMarker sgcm(SvcGCMarker::MINOR); 2836 ResourceMark rm; 2837 2838 g1_policy()->note_gc_start(); 2839 2840 wait_for_root_region_scanning(); 2841 2842 print_heap_before_gc(); 2843 print_heap_regions(); 2844 trace_heap_before_gc(_gc_tracer_stw); 2845 2846 _verifier->verify_region_sets_optional(); 2847 _verifier->verify_dirty_young_regions(); 2848 2849 // We should not be doing initial mark unless the conc mark thread is running 2850 if (!_cmThread->should_terminate()) { 2851 // This call will decide whether this pause is an initial-mark 2852 // pause. If it is, during_initial_mark_pause() will return true 2853 // for the duration of this pause. 2854 g1_policy()->decide_on_conc_mark_initiation(); 2855 } 2856 2857 // We do not allow initial-mark to be piggy-backed on a mixed GC. 2858 assert(!collector_state()->during_initial_mark_pause() || 2859 collector_state()->gcs_are_young(), "sanity"); 2860 2861 // We also do not allow mixed GCs during marking. 2862 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity"); 2863 2864 // Record whether this pause is an initial mark. When the current 2865 // thread has completed its logging output and it's safe to signal 2866 // the CM thread, the flag's value in the policy has been reset. 2867 bool should_start_conc_mark = collector_state()->during_initial_mark_pause(); 2868 2869 // Inner scope for scope based logging, timers, and stats collection 2870 { 2871 EvacuationInfo evacuation_info; 2872 2873 if (collector_state()->during_initial_mark_pause()) { 2874 // We are about to start a marking cycle, so we increment the 2875 // full collection counter. 2876 increment_old_marking_cycles_started(); 2877 _cm->gc_tracer_cm()->set_gc_cause(gc_cause()); 2878 } 2879 2880 _gc_tracer_stw->report_yc_type(collector_state()->yc_type()); 2881 2882 GCTraceCPUTime tcpu; 2883 2884 G1HeapVerifier::G1VerifyType verify_type; 2885 FormatBuffer<> gc_string("Pause "); 2886 if (collector_state()->during_initial_mark_pause()) { 2887 gc_string.append("Initial Mark"); 2888 verify_type = G1HeapVerifier::G1VerifyInitialMark; 2889 } else if (collector_state()->gcs_are_young()) { 2890 gc_string.append("Young"); 2891 verify_type = G1HeapVerifier::G1VerifyYoungOnly; 2892 } else { 2893 gc_string.append("Mixed"); 2894 verify_type = G1HeapVerifier::G1VerifyMixed; 2895 } 2896 GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true); 2897 2898 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 2899 workers()->active_workers(), 2900 Threads::number_of_non_daemon_threads()); 2901 workers()->update_active_workers(active_workers); 2902 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers()); 2903 2904 TraceCollectorStats tcs(g1mm()->incremental_collection_counters()); 2905 TraceMemoryManagerStats tms(&_memory_manager, gc_cause()); 2906 2907 // If the secondary_free_list is not empty, append it to the 2908 // free_list. No need to wait for the cleanup operation to finish; 2909 // the region allocation code will check the secondary_free_list 2910 // and wait if necessary. If the G1StressConcRegionFreeing flag is 2911 // set, skip this step so that the region allocation code has to 2912 // get entries from the secondary_free_list. 2913 if (!G1StressConcRegionFreeing) { 2914 append_secondary_free_list_if_not_empty_with_lock(); 2915 } 2916 2917 G1HeapTransition heap_transition(this); 2918 size_t heap_used_bytes_before_gc = used(); 2919 2920 // Don't dynamically change the number of GC threads this early. A value of 2921 // 0 is used to indicate serial work. When parallel work is done, 2922 // it will be set. 2923 2924 { // Call to jvmpi::post_class_unload_events must occur outside of active GC 2925 IsGCActiveMark x; 2926 2927 gc_prologue(false); 2928 2929 if (VerifyRememberedSets) { 2930 log_info(gc, verify)("[Verifying RemSets before GC]"); 2931 VerifyRegionRemSetClosure v_cl; 2932 heap_region_iterate(&v_cl); 2933 } 2934 2935 _verifier->verify_before_gc(verify_type); 2936 2937 _verifier->check_bitmaps("GC Start"); 2938 2939 #if COMPILER2_OR_JVMCI 2940 DerivedPointerTable::clear(); 2941 #endif 2942 2943 // Please see comment in g1CollectedHeap.hpp and 2944 // G1CollectedHeap::ref_processing_init() to see how 2945 // reference processing currently works in G1. 2946 2947 // Enable discovery in the STW reference processor 2948 if (g1_policy()->should_process_references()) { 2949 ref_processor_stw()->enable_discovery(); 2950 } else { 2951 ref_processor_stw()->disable_discovery(); 2952 } 2953 2954 { 2955 // We want to temporarily turn off discovery by the 2956 // CM ref processor, if necessary, and turn it back on 2957 // on again later if we do. Using a scoped 2958 // NoRefDiscovery object will do this. 2959 NoRefDiscovery no_cm_discovery(ref_processor_cm()); 2960 2961 // Forget the current alloc region (we might even choose it to be part 2962 // of the collection set!). 2963 _allocator->release_mutator_alloc_region(); 2964 2965 // This timing is only used by the ergonomics to handle our pause target. 2966 // It is unclear why this should not include the full pause. We will 2967 // investigate this in CR 7178365. 2968 // 2969 // Preserving the old comment here if that helps the investigation: 2970 // 2971 // The elapsed time induced by the start time below deliberately elides 2972 // the possible verification above. 2973 double sample_start_time_sec = os::elapsedTime(); 2974 2975 g1_policy()->record_collection_pause_start(sample_start_time_sec); 2976 2977 if (collector_state()->during_initial_mark_pause()) { 2978 concurrent_mark()->checkpoint_roots_initial_pre(); 2979 } 2980 2981 g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor); 2982 2983 evacuation_info.set_collectionset_regions(collection_set()->region_length()); 2984 2985 // Make sure the remembered sets are up to date. This needs to be 2986 // done before register_humongous_regions_with_cset(), because the 2987 // remembered sets are used there to choose eager reclaim candidates. 2988 // If the remembered sets are not up to date we might miss some 2989 // entries that need to be handled. 2990 g1_rem_set()->cleanupHRRS(); 2991 2992 register_humongous_regions_with_cset(); 2993 2994 assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table."); 2995 2996 // We call this after finalize_cset() to 2997 // ensure that the CSet has been finalized. 2998 _cm->verify_no_cset_oops(); 2999 3000 if (_hr_printer.is_active()) { 3001 G1PrintCollectionSetClosure cl(&_hr_printer); 3002 _collection_set.iterate(&cl); 3003 } 3004 3005 // Initialize the GC alloc regions. 3006 _allocator->init_gc_alloc_regions(evacuation_info); 3007 3008 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length()); 3009 pre_evacuate_collection_set(); 3010 3011 // Actually do the work... 3012 evacuate_collection_set(&per_thread_states); 3013 3014 post_evacuate_collection_set(evacuation_info, &per_thread_states); 3015 3016 const size_t* surviving_young_words = per_thread_states.surviving_young_words(); 3017 free_collection_set(&_collection_set, evacuation_info, surviving_young_words); 3018 3019 eagerly_reclaim_humongous_regions(); 3020 3021 record_obj_copy_mem_stats(); 3022 _survivor_evac_stats.adjust_desired_plab_sz(); 3023 _old_evac_stats.adjust_desired_plab_sz(); 3024 3025 double start = os::elapsedTime(); 3026 start_new_collection_set(); 3027 g1_policy()->phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0); 3028 3029 if (evacuation_failed()) { 3030 set_used(recalculate_used()); 3031 if (_archive_allocator != NULL) { 3032 _archive_allocator->clear_used(); 3033 } 3034 for (uint i = 0; i < ParallelGCThreads; i++) { 3035 if (_evacuation_failed_info_array[i].has_failed()) { 3036 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]); 3037 } 3038 } 3039 } else { 3040 // The "used" of the the collection set have already been subtracted 3041 // when they were freed. Add in the bytes evacuated. 3042 increase_used(g1_policy()->bytes_copied_during_gc()); 3043 } 3044 3045 if (collector_state()->during_initial_mark_pause()) { 3046 // We have to do this before we notify the CM threads that 3047 // they can start working to make sure that all the 3048 // appropriate initialization is done on the CM object. 3049 concurrent_mark()->checkpoint_roots_initial_post(); 3050 collector_state()->set_mark_in_progress(true); 3051 // Note that we don't actually trigger the CM thread at 3052 // this point. We do that later when we're sure that 3053 // the current thread has completed its logging output. 3054 } 3055 3056 allocate_dummy_regions(); 3057 3058 _allocator->init_mutator_alloc_region(); 3059 3060 { 3061 size_t expand_bytes = _heap_sizing_policy->expansion_amount(); 3062 if (expand_bytes > 0) { 3063 size_t bytes_before = capacity(); 3064 // No need for an ergo logging here, 3065 // expansion_amount() does this when it returns a value > 0. 3066 double expand_ms; 3067 if (!expand(expand_bytes, _workers, &expand_ms)) { 3068 // We failed to expand the heap. Cannot do anything about it. 3069 } 3070 g1_policy()->phase_times()->record_expand_heap_time(expand_ms); 3071 } 3072 } 3073 3074 // We redo the verification but now wrt to the new CSet which 3075 // has just got initialized after the previous CSet was freed. 3076 _cm->verify_no_cset_oops(); 3077 3078 // This timing is only used by the ergonomics to handle our pause target. 3079 // It is unclear why this should not include the full pause. We will 3080 // investigate this in CR 7178365. 3081 double sample_end_time_sec = os::elapsedTime(); 3082 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; 3083 size_t total_cards_scanned = g1_policy()->phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScanRSScannedCards); 3084 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc); 3085 3086 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before()); 3087 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc()); 3088 3089 if (VerifyRememberedSets) { 3090 log_info(gc, verify)("[Verifying RemSets after GC]"); 3091 VerifyRegionRemSetClosure v_cl; 3092 heap_region_iterate(&v_cl); 3093 } 3094 3095 _verifier->verify_after_gc(verify_type); 3096 _verifier->check_bitmaps("GC End"); 3097 3098 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 3099 ref_processor_stw()->verify_no_references_recorded(); 3100 3101 // CM reference discovery will be re-enabled if necessary. 3102 } 3103 3104 #ifdef TRACESPINNING 3105 ParallelTaskTerminator::print_termination_counts(); 3106 #endif 3107 3108 gc_epilogue(false); 3109 } 3110 3111 // Print the remainder of the GC log output. 3112 if (evacuation_failed()) { 3113 log_info(gc)("To-space exhausted"); 3114 } 3115 3116 g1_policy()->print_phases(); 3117 heap_transition.print(); 3118 3119 // It is not yet to safe to tell the concurrent mark to 3120 // start as we have some optional output below. We don't want the 3121 // output from the concurrent mark thread interfering with this 3122 // logging output either. 3123 3124 _hrm.verify_optional(); 3125 _verifier->verify_region_sets_optional(); 3126 3127 TASKQUEUE_STATS_ONLY(print_taskqueue_stats()); 3128 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); 3129 3130 print_heap_after_gc(); 3131 print_heap_regions(); 3132 trace_heap_after_gc(_gc_tracer_stw); 3133 3134 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 3135 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 3136 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 3137 // before any GC notifications are raised. 3138 g1mm()->update_sizes(); 3139 3140 _gc_tracer_stw->report_evacuation_info(&evacuation_info); 3141 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold()); 3142 _gc_timer_stw->register_gc_end(); 3143 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions()); 3144 } 3145 // It should now be safe to tell the concurrent mark thread to start 3146 // without its logging output interfering with the logging output 3147 // that came from the pause. 3148 3149 if (should_start_conc_mark) { 3150 // CAUTION: after the doConcurrentMark() call below, 3151 // the concurrent marking thread(s) could be running 3152 // concurrently with us. Make sure that anything after 3153 // this point does not assume that we are the only GC thread 3154 // running. Note: of course, the actual marking work will 3155 // not start until the safepoint itself is released in 3156 // SuspendibleThreadSet::desynchronize(). 3157 doConcurrentMark(); 3158 } 3159 3160 return true; 3161 } 3162 3163 void G1CollectedHeap::remove_self_forwarding_pointers() { 3164 G1ParRemoveSelfForwardPtrsTask rsfp_task; 3165 workers()->run_task(&rsfp_task); 3166 } 3167 3168 void G1CollectedHeap::restore_after_evac_failure() { 3169 double remove_self_forwards_start = os::elapsedTime(); 3170 3171 remove_self_forwarding_pointers(); 3172 SharedRestorePreservedMarksTaskExecutor task_executor(workers()); 3173 _preserved_marks_set.restore(&task_executor); 3174 3175 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0); 3176 } 3177 3178 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) { 3179 if (!_evacuation_failed) { 3180 _evacuation_failed = true; 3181 } 3182 3183 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size()); 3184 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m); 3185 } 3186 3187 bool G1ParEvacuateFollowersClosure::offer_termination() { 3188 G1ParScanThreadState* const pss = par_scan_state(); 3189 start_term_time(); 3190 const bool res = terminator()->offer_termination(); 3191 end_term_time(); 3192 return res; 3193 } 3194 3195 void G1ParEvacuateFollowersClosure::do_void() { 3196 G1ParScanThreadState* const pss = par_scan_state(); 3197 pss->trim_queue(); 3198 do { 3199 pss->steal_and_trim_queue(queues()); 3200 } while (!offer_termination()); 3201 } 3202 3203 class G1ParTask : public AbstractGangTask { 3204 protected: 3205 G1CollectedHeap* _g1h; 3206 G1ParScanThreadStateSet* _pss; 3207 RefToScanQueueSet* _queues; 3208 G1RootProcessor* _root_processor; 3209 ParallelTaskTerminator _terminator; 3210 uint _n_workers; 3211 3212 public: 3213 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers) 3214 : AbstractGangTask("G1 collection"), 3215 _g1h(g1h), 3216 _pss(per_thread_states), 3217 _queues(task_queues), 3218 _root_processor(root_processor), 3219 _terminator(n_workers, _queues), 3220 _n_workers(n_workers) 3221 {} 3222 3223 void work(uint worker_id) { 3224 if (worker_id >= _n_workers) return; // no work needed this round 3225 3226 double start_sec = os::elapsedTime(); 3227 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec); 3228 3229 { 3230 ResourceMark rm; 3231 HandleMark hm; 3232 3233 ReferenceProcessor* rp = _g1h->ref_processor_stw(); 3234 3235 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 3236 pss->set_ref_processor(rp); 3237 3238 double start_strong_roots_sec = os::elapsedTime(); 3239 3240 _root_processor->evacuate_roots(pss->closures(), worker_id); 3241 3242 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid 3243 // treating the nmethods visited to act as roots for concurrent marking. 3244 // We only want to make sure that the oops in the nmethods are adjusted with regard to the 3245 // objects copied by the current evacuation. 3246 _g1h->g1_rem_set()->oops_into_collection_set_do(pss, 3247 pss->closures()->weak_codeblobs(), 3248 worker_id); 3249 3250 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec; 3251 3252 double term_sec = 0.0; 3253 size_t evac_term_attempts = 0; 3254 { 3255 double start = os::elapsedTime(); 3256 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator); 3257 evac.do_void(); 3258 3259 evac_term_attempts = evac.term_attempts(); 3260 term_sec = evac.term_time(); 3261 double elapsed_sec = os::elapsedTime() - start; 3262 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec); 3263 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec); 3264 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts); 3265 } 3266 3267 assert(pss->queue_is_empty(), "should be empty"); 3268 3269 if (log_is_enabled(Debug, gc, task, stats)) { 3270 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); 3271 size_t lab_waste; 3272 size_t lab_undo_waste; 3273 pss->waste(lab_waste, lab_undo_waste); 3274 _g1h->print_termination_stats(worker_id, 3275 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */ 3276 strong_roots_sec * 1000.0, /* strong roots time */ 3277 term_sec * 1000.0, /* evac term time */ 3278 evac_term_attempts, /* evac term attempts */ 3279 lab_waste, /* alloc buffer waste */ 3280 lab_undo_waste /* undo waste */ 3281 ); 3282 } 3283 3284 // Close the inner scope so that the ResourceMark and HandleMark 3285 // destructors are executed here and are included as part of the 3286 // "GC Worker Time". 3287 } 3288 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime()); 3289 } 3290 }; 3291 3292 void G1CollectedHeap::print_termination_stats_hdr() { 3293 log_debug(gc, task, stats)("GC Termination Stats"); 3294 log_debug(gc, task, stats)(" elapsed --strong roots-- -------termination------- ------waste (KiB)------"); 3295 log_debug(gc, task, stats)("thr ms ms %% ms %% attempts total alloc undo"); 3296 log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------"); 3297 } 3298 3299 void G1CollectedHeap::print_termination_stats(uint worker_id, 3300 double elapsed_ms, 3301 double strong_roots_ms, 3302 double term_ms, 3303 size_t term_attempts, 3304 size_t alloc_buffer_waste, 3305 size_t undo_waste) const { 3306 log_debug(gc, task, stats) 3307 ("%3d %9.2f %9.2f %6.2f " 3308 "%9.2f %6.2f " SIZE_FORMAT_W(8) " " 3309 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7), 3310 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms, 3311 term_ms, term_ms * 100 / elapsed_ms, term_attempts, 3312 (alloc_buffer_waste + undo_waste) * HeapWordSize / K, 3313 alloc_buffer_waste * HeapWordSize / K, 3314 undo_waste * HeapWordSize / K); 3315 } 3316 3317 class G1StringAndSymbolCleaningTask : public AbstractGangTask { 3318 private: 3319 BoolObjectClosure* _is_alive; 3320 G1StringDedupUnlinkOrOopsDoClosure _dedup_closure; 3321 3322 int _initial_string_table_size; 3323 int _initial_symbol_table_size; 3324 3325 bool _process_strings; 3326 int _strings_processed; 3327 int _strings_removed; 3328 3329 bool _process_symbols; 3330 int _symbols_processed; 3331 int _symbols_removed; 3332 3333 bool _process_string_dedup; 3334 3335 public: 3336 G1StringAndSymbolCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool process_string_dedup) : 3337 AbstractGangTask("String/Symbol Unlinking"), 3338 _is_alive(is_alive), 3339 _dedup_closure(is_alive, NULL, false), 3340 _process_strings(process_strings), _strings_processed(0), _strings_removed(0), 3341 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0), 3342 _process_string_dedup(process_string_dedup) { 3343 3344 _initial_string_table_size = StringTable::the_table()->table_size(); 3345 _initial_symbol_table_size = SymbolTable::the_table()->table_size(); 3346 if (process_strings) { 3347 StringTable::clear_parallel_claimed_index(); 3348 } 3349 if (process_symbols) { 3350 SymbolTable::clear_parallel_claimed_index(); 3351 } 3352 } 3353 3354 ~G1StringAndSymbolCleaningTask() { 3355 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size, 3356 "claim value %d after unlink less than initial string table size %d", 3357 StringTable::parallel_claimed_index(), _initial_string_table_size); 3358 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size, 3359 "claim value %d after unlink less than initial symbol table size %d", 3360 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size); 3361 3362 log_info(gc, stringtable)( 3363 "Cleaned string and symbol table, " 3364 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, " 3365 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed", 3366 strings_processed(), strings_removed(), 3367 symbols_processed(), symbols_removed()); 3368 } 3369 3370 void work(uint worker_id) { 3371 int strings_processed = 0; 3372 int strings_removed = 0; 3373 int symbols_processed = 0; 3374 int symbols_removed = 0; 3375 if (_process_strings) { 3376 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed); 3377 Atomic::add(strings_processed, &_strings_processed); 3378 Atomic::add(strings_removed, &_strings_removed); 3379 } 3380 if (_process_symbols) { 3381 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed); 3382 Atomic::add(symbols_processed, &_symbols_processed); 3383 Atomic::add(symbols_removed, &_symbols_removed); 3384 } 3385 if (_process_string_dedup) { 3386 G1StringDedup::parallel_unlink(&_dedup_closure, worker_id); 3387 } 3388 } 3389 3390 size_t strings_processed() const { return (size_t)_strings_processed; } 3391 size_t strings_removed() const { return (size_t)_strings_removed; } 3392 3393 size_t symbols_processed() const { return (size_t)_symbols_processed; } 3394 size_t symbols_removed() const { return (size_t)_symbols_removed; } 3395 }; 3396 3397 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC { 3398 private: 3399 static Monitor* _lock; 3400 3401 BoolObjectClosure* const _is_alive; 3402 const bool _unloading_occurred; 3403 const uint _num_workers; 3404 3405 // Variables used to claim nmethods. 3406 CompiledMethod* _first_nmethod; 3407 CompiledMethod* volatile _claimed_nmethod; 3408 3409 // The list of nmethods that need to be processed by the second pass. 3410 CompiledMethod* volatile _postponed_list; 3411 volatile uint _num_entered_barrier; 3412 3413 public: 3414 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) : 3415 _is_alive(is_alive), 3416 _unloading_occurred(unloading_occurred), 3417 _num_workers(num_workers), 3418 _first_nmethod(NULL), 3419 _claimed_nmethod(NULL), 3420 _postponed_list(NULL), 3421 _num_entered_barrier(0) 3422 { 3423 CompiledMethod::increase_unloading_clock(); 3424 // Get first alive nmethod 3425 CompiledMethodIterator iter = CompiledMethodIterator(); 3426 if(iter.next_alive()) { 3427 _first_nmethod = iter.method(); 3428 } 3429 _claimed_nmethod = _first_nmethod; 3430 } 3431 3432 ~G1CodeCacheUnloadingTask() { 3433 CodeCache::verify_clean_inline_caches(); 3434 3435 CodeCache::set_needs_cache_clean(false); 3436 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be"); 3437 3438 CodeCache::verify_icholder_relocations(); 3439 } 3440 3441 private: 3442 void add_to_postponed_list(CompiledMethod* nm) { 3443 CompiledMethod* old; 3444 do { 3445 old = _postponed_list; 3446 nm->set_unloading_next(old); 3447 } while (Atomic::cmpxchg(nm, &_postponed_list, old) != old); 3448 } 3449 3450 void clean_nmethod(CompiledMethod* nm) { 3451 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred); 3452 3453 if (postponed) { 3454 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet. 3455 add_to_postponed_list(nm); 3456 } 3457 3458 // Mark that this thread has been cleaned/unloaded. 3459 // After this call, it will be safe to ask if this nmethod was unloaded or not. 3460 nm->set_unloading_clock(CompiledMethod::global_unloading_clock()); 3461 } 3462 3463 void clean_nmethod_postponed(CompiledMethod* nm) { 3464 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred); 3465 } 3466 3467 static const int MaxClaimNmethods = 16; 3468 3469 void claim_nmethods(CompiledMethod** claimed_nmethods, int *num_claimed_nmethods) { 3470 CompiledMethod* first; 3471 CompiledMethodIterator last; 3472 3473 do { 3474 *num_claimed_nmethods = 0; 3475 3476 first = _claimed_nmethod; 3477 last = CompiledMethodIterator(first); 3478 3479 if (first != NULL) { 3480 3481 for (int i = 0; i < MaxClaimNmethods; i++) { 3482 if (!last.next_alive()) { 3483 break; 3484 } 3485 claimed_nmethods[i] = last.method(); 3486 (*num_claimed_nmethods)++; 3487 } 3488 } 3489 3490 } while (Atomic::cmpxchg(last.method(), &_claimed_nmethod, first) != first); 3491 } 3492 3493 CompiledMethod* claim_postponed_nmethod() { 3494 CompiledMethod* claim; 3495 CompiledMethod* next; 3496 3497 do { 3498 claim = _postponed_list; 3499 if (claim == NULL) { 3500 return NULL; 3501 } 3502 3503 next = claim->unloading_next(); 3504 3505 } while (Atomic::cmpxchg(next, &_postponed_list, claim) != claim); 3506 3507 return claim; 3508 } 3509 3510 public: 3511 // Mark that we're done with the first pass of nmethod cleaning. 3512 void barrier_mark(uint worker_id) { 3513 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 3514 _num_entered_barrier++; 3515 if (_num_entered_barrier == _num_workers) { 3516 ml.notify_all(); 3517 } 3518 } 3519 3520 // See if we have to wait for the other workers to 3521 // finish their first-pass nmethod cleaning work. 3522 void barrier_wait(uint worker_id) { 3523 if (_num_entered_barrier < _num_workers) { 3524 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 3525 while (_num_entered_barrier < _num_workers) { 3526 ml.wait(Mutex::_no_safepoint_check_flag, 0, false); 3527 } 3528 } 3529 } 3530 3531 // Cleaning and unloading of nmethods. Some work has to be postponed 3532 // to the second pass, when we know which nmethods survive. 3533 void work_first_pass(uint worker_id) { 3534 // The first nmethods is claimed by the first worker. 3535 if (worker_id == 0 && _first_nmethod != NULL) { 3536 clean_nmethod(_first_nmethod); 3537 _first_nmethod = NULL; 3538 } 3539 3540 int num_claimed_nmethods; 3541 CompiledMethod* claimed_nmethods[MaxClaimNmethods]; 3542 3543 while (true) { 3544 claim_nmethods(claimed_nmethods, &num_claimed_nmethods); 3545 3546 if (num_claimed_nmethods == 0) { 3547 break; 3548 } 3549 3550 for (int i = 0; i < num_claimed_nmethods; i++) { 3551 clean_nmethod(claimed_nmethods[i]); 3552 } 3553 } 3554 } 3555 3556 void work_second_pass(uint worker_id) { 3557 CompiledMethod* nm; 3558 // Take care of postponed nmethods. 3559 while ((nm = claim_postponed_nmethod()) != NULL) { 3560 clean_nmethod_postponed(nm); 3561 } 3562 } 3563 }; 3564 3565 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never); 3566 3567 class G1KlassCleaningTask : public StackObj { 3568 BoolObjectClosure* _is_alive; 3569 volatile int _clean_klass_tree_claimed; 3570 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator; 3571 3572 public: 3573 G1KlassCleaningTask(BoolObjectClosure* is_alive) : 3574 _is_alive(is_alive), 3575 _clean_klass_tree_claimed(0), 3576 _klass_iterator() { 3577 } 3578 3579 private: 3580 bool claim_clean_klass_tree_task() { 3581 if (_clean_klass_tree_claimed) { 3582 return false; 3583 } 3584 3585 return Atomic::cmpxchg(1, &_clean_klass_tree_claimed, 0) == 0; 3586 } 3587 3588 InstanceKlass* claim_next_klass() { 3589 Klass* klass; 3590 do { 3591 klass =_klass_iterator.next_klass(); 3592 } while (klass != NULL && !klass->is_instance_klass()); 3593 3594 // this can be null so don't call InstanceKlass::cast 3595 return static_cast<InstanceKlass*>(klass); 3596 } 3597 3598 public: 3599 3600 void clean_klass(InstanceKlass* ik) { 3601 ik->clean_weak_instanceklass_links(_is_alive); 3602 } 3603 3604 void work() { 3605 ResourceMark rm; 3606 3607 // One worker will clean the subklass/sibling klass tree. 3608 if (claim_clean_klass_tree_task()) { 3609 Klass::clean_subklass_tree(_is_alive); 3610 } 3611 3612 // All workers will help cleaning the classes, 3613 InstanceKlass* klass; 3614 while ((klass = claim_next_klass()) != NULL) { 3615 clean_klass(klass); 3616 } 3617 } 3618 }; 3619 3620 class G1ResolvedMethodCleaningTask : public StackObj { 3621 BoolObjectClosure* _is_alive; 3622 volatile int _resolved_method_task_claimed; 3623 public: 3624 G1ResolvedMethodCleaningTask(BoolObjectClosure* is_alive) : 3625 _is_alive(is_alive), _resolved_method_task_claimed(0) {} 3626 3627 bool claim_resolved_method_task() { 3628 if (_resolved_method_task_claimed) { 3629 return false; 3630 } 3631 return Atomic::cmpxchg(1, &_resolved_method_task_claimed, 0) == 0; 3632 } 3633 3634 // These aren't big, one thread can do it all. 3635 void work() { 3636 if (claim_resolved_method_task()) { 3637 ResolvedMethodTable::unlink(_is_alive); 3638 } 3639 } 3640 }; 3641 3642 3643 // To minimize the remark pause times, the tasks below are done in parallel. 3644 class G1ParallelCleaningTask : public AbstractGangTask { 3645 private: 3646 G1StringAndSymbolCleaningTask _string_symbol_task; 3647 G1CodeCacheUnloadingTask _code_cache_task; 3648 G1KlassCleaningTask _klass_cleaning_task; 3649 G1ResolvedMethodCleaningTask _resolved_method_cleaning_task; 3650 3651 public: 3652 // The constructor is run in the VMThread. 3653 G1ParallelCleaningTask(BoolObjectClosure* is_alive, uint num_workers, bool unloading_occurred) : 3654 AbstractGangTask("Parallel Cleaning"), 3655 _string_symbol_task(is_alive, true, true, G1StringDedup::is_enabled()), 3656 _code_cache_task(num_workers, is_alive, unloading_occurred), 3657 _klass_cleaning_task(is_alive), 3658 _resolved_method_cleaning_task(is_alive) { 3659 } 3660 3661 // The parallel work done by all worker threads. 3662 void work(uint worker_id) { 3663 // Do first pass of code cache cleaning. 3664 _code_cache_task.work_first_pass(worker_id); 3665 3666 // Let the threads mark that the first pass is done. 3667 _code_cache_task.barrier_mark(worker_id); 3668 3669 // Clean the Strings and Symbols. 3670 _string_symbol_task.work(worker_id); 3671 3672 // Clean unreferenced things in the ResolvedMethodTable 3673 _resolved_method_cleaning_task.work(); 3674 3675 // Wait for all workers to finish the first code cache cleaning pass. 3676 _code_cache_task.barrier_wait(worker_id); 3677 3678 // Do the second code cache cleaning work, which realize on 3679 // the liveness information gathered during the first pass. 3680 _code_cache_task.work_second_pass(worker_id); 3681 3682 // Clean all klasses that were not unloaded. 3683 _klass_cleaning_task.work(); 3684 } 3685 }; 3686 3687 3688 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive, 3689 bool class_unloading_occurred) { 3690 uint n_workers = workers()->active_workers(); 3691 3692 G1ParallelCleaningTask g1_unlink_task(is_alive, n_workers, class_unloading_occurred); 3693 workers()->run_task(&g1_unlink_task); 3694 } 3695 3696 void G1CollectedHeap::partial_cleaning(BoolObjectClosure* is_alive, 3697 bool process_strings, 3698 bool process_symbols, 3699 bool process_string_dedup) { 3700 if (!process_strings && !process_symbols && !process_string_dedup) { 3701 // Nothing to clean. 3702 return; 3703 } 3704 3705 G1StringAndSymbolCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, process_string_dedup); 3706 workers()->run_task(&g1_unlink_task); 3707 3708 } 3709 3710 class G1RedirtyLoggedCardsTask : public AbstractGangTask { 3711 private: 3712 DirtyCardQueueSet* _queue; 3713 G1CollectedHeap* _g1h; 3714 public: 3715 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"), 3716 _queue(queue), _g1h(g1h) { } 3717 3718 virtual void work(uint worker_id) { 3719 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times(); 3720 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id); 3721 3722 RedirtyLoggedCardTableEntryClosure cl(_g1h); 3723 _queue->par_apply_closure_to_all_completed_buffers(&cl); 3724 3725 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied()); 3726 } 3727 }; 3728 3729 void G1CollectedHeap::redirty_logged_cards() { 3730 double redirty_logged_cards_start = os::elapsedTime(); 3731 3732 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this); 3733 dirty_card_queue_set().reset_for_par_iteration(); 3734 workers()->run_task(&redirty_task); 3735 3736 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set(); 3737 dcq.merge_bufferlists(&dirty_card_queue_set()); 3738 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed"); 3739 3740 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0); 3741 } 3742 3743 // Weak Reference Processing support 3744 3745 // An always "is_alive" closure that is used to preserve referents. 3746 // If the object is non-null then it's alive. Used in the preservation 3747 // of referent objects that are pointed to by reference objects 3748 // discovered by the CM ref processor. 3749 class G1AlwaysAliveClosure: public BoolObjectClosure { 3750 G1CollectedHeap* _g1; 3751 public: 3752 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 3753 bool do_object_b(oop p) { 3754 if (p != NULL) { 3755 return true; 3756 } 3757 return false; 3758 } 3759 }; 3760 3761 bool G1STWIsAliveClosure::do_object_b(oop p) { 3762 // An object is reachable if it is outside the collection set, 3763 // or is inside and copied. 3764 return !_g1->is_in_cset(p) || p->is_forwarded(); 3765 } 3766 3767 // Non Copying Keep Alive closure 3768 class G1KeepAliveClosure: public OopClosure { 3769 G1CollectedHeap* _g1; 3770 public: 3771 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 3772 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } 3773 void do_oop(oop* p) { 3774 oop obj = *p; 3775 assert(obj != NULL, "the caller should have filtered out NULL values"); 3776 3777 const InCSetState cset_state = _g1->in_cset_state(obj); 3778 if (!cset_state.is_in_cset_or_humongous()) { 3779 return; 3780 } 3781 if (cset_state.is_in_cset()) { 3782 assert( obj->is_forwarded(), "invariant" ); 3783 *p = obj->forwardee(); 3784 } else { 3785 assert(!obj->is_forwarded(), "invariant" ); 3786 assert(cset_state.is_humongous(), 3787 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value()); 3788 _g1->set_humongous_is_live(obj); 3789 } 3790 } 3791 }; 3792 3793 // Copying Keep Alive closure - can be called from both 3794 // serial and parallel code as long as different worker 3795 // threads utilize different G1ParScanThreadState instances 3796 // and different queues. 3797 3798 class G1CopyingKeepAliveClosure: public OopClosure { 3799 G1CollectedHeap* _g1h; 3800 OopClosure* _copy_non_heap_obj_cl; 3801 G1ParScanThreadState* _par_scan_state; 3802 3803 public: 3804 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, 3805 OopClosure* non_heap_obj_cl, 3806 G1ParScanThreadState* pss): 3807 _g1h(g1h), 3808 _copy_non_heap_obj_cl(non_heap_obj_cl), 3809 _par_scan_state(pss) 3810 {} 3811 3812 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 3813 virtual void do_oop( oop* p) { do_oop_work(p); } 3814 3815 template <class T> void do_oop_work(T* p) { 3816 oop obj = oopDesc::load_decode_heap_oop(p); 3817 3818 if (_g1h->is_in_cset_or_humongous(obj)) { 3819 // If the referent object has been forwarded (either copied 3820 // to a new location or to itself in the event of an 3821 // evacuation failure) then we need to update the reference 3822 // field and, if both reference and referent are in the G1 3823 // heap, update the RSet for the referent. 3824 // 3825 // If the referent has not been forwarded then we have to keep 3826 // it alive by policy. Therefore we have copy the referent. 3827 // 3828 // If the reference field is in the G1 heap then we can push 3829 // on the PSS queue. When the queue is drained (after each 3830 // phase of reference processing) the object and it's followers 3831 // will be copied, the reference field set to point to the 3832 // new location, and the RSet updated. Otherwise we need to 3833 // use the the non-heap or metadata closures directly to copy 3834 // the referent object and update the pointer, while avoiding 3835 // updating the RSet. 3836 3837 if (_g1h->is_in_g1_reserved(p)) { 3838 _par_scan_state->push_on_queue(p); 3839 } else { 3840 assert(!Metaspace::contains((const void*)p), 3841 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p)); 3842 _copy_non_heap_obj_cl->do_oop(p); 3843 } 3844 } 3845 } 3846 }; 3847 3848 // Serial drain queue closure. Called as the 'complete_gc' 3849 // closure for each discovered list in some of the 3850 // reference processing phases. 3851 3852 class G1STWDrainQueueClosure: public VoidClosure { 3853 protected: 3854 G1CollectedHeap* _g1h; 3855 G1ParScanThreadState* _par_scan_state; 3856 3857 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 3858 3859 public: 3860 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : 3861 _g1h(g1h), 3862 _par_scan_state(pss) 3863 { } 3864 3865 void do_void() { 3866 G1ParScanThreadState* const pss = par_scan_state(); 3867 pss->trim_queue(); 3868 } 3869 }; 3870 3871 // Parallel Reference Processing closures 3872 3873 // Implementation of AbstractRefProcTaskExecutor for parallel reference 3874 // processing during G1 evacuation pauses. 3875 3876 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 3877 private: 3878 G1CollectedHeap* _g1h; 3879 G1ParScanThreadStateSet* _pss; 3880 RefToScanQueueSet* _queues; 3881 WorkGang* _workers; 3882 uint _active_workers; 3883 3884 public: 3885 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, 3886 G1ParScanThreadStateSet* per_thread_states, 3887 WorkGang* workers, 3888 RefToScanQueueSet *task_queues, 3889 uint n_workers) : 3890 _g1h(g1h), 3891 _pss(per_thread_states), 3892 _queues(task_queues), 3893 _workers(workers), 3894 _active_workers(n_workers) 3895 { 3896 g1h->ref_processor_stw()->set_active_mt_degree(n_workers); 3897 } 3898 3899 // Executes the given task using concurrent marking worker threads. 3900 virtual void execute(ProcessTask& task); 3901 virtual void execute(EnqueueTask& task); 3902 }; 3903 3904 // Gang task for possibly parallel reference processing 3905 3906 class G1STWRefProcTaskProxy: public AbstractGangTask { 3907 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 3908 ProcessTask& _proc_task; 3909 G1CollectedHeap* _g1h; 3910 G1ParScanThreadStateSet* _pss; 3911 RefToScanQueueSet* _task_queues; 3912 ParallelTaskTerminator* _terminator; 3913 3914 public: 3915 G1STWRefProcTaskProxy(ProcessTask& proc_task, 3916 G1CollectedHeap* g1h, 3917 G1ParScanThreadStateSet* per_thread_states, 3918 RefToScanQueueSet *task_queues, 3919 ParallelTaskTerminator* terminator) : 3920 AbstractGangTask("Process reference objects in parallel"), 3921 _proc_task(proc_task), 3922 _g1h(g1h), 3923 _pss(per_thread_states), 3924 _task_queues(task_queues), 3925 _terminator(terminator) 3926 {} 3927 3928 virtual void work(uint worker_id) { 3929 // The reference processing task executed by a single worker. 3930 ResourceMark rm; 3931 HandleMark hm; 3932 3933 G1STWIsAliveClosure is_alive(_g1h); 3934 3935 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 3936 pss->set_ref_processor(NULL); 3937 3938 // Keep alive closure. 3939 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss); 3940 3941 // Complete GC closure 3942 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator); 3943 3944 // Call the reference processing task's work routine. 3945 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); 3946 3947 // Note we cannot assert that the refs array is empty here as not all 3948 // of the processing tasks (specifically phase2 - pp2_work) execute 3949 // the complete_gc closure (which ordinarily would drain the queue) so 3950 // the queue may not be empty. 3951 } 3952 }; 3953 3954 // Driver routine for parallel reference processing. 3955 // Creates an instance of the ref processing gang 3956 // task and has the worker threads execute it. 3957 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) { 3958 assert(_workers != NULL, "Need parallel worker threads."); 3959 3960 ParallelTaskTerminator terminator(_active_workers, _queues); 3961 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator); 3962 3963 _workers->run_task(&proc_task_proxy); 3964 } 3965 3966 // Gang task for parallel reference enqueueing. 3967 3968 class G1STWRefEnqueueTaskProxy: public AbstractGangTask { 3969 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; 3970 EnqueueTask& _enq_task; 3971 3972 public: 3973 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) : 3974 AbstractGangTask("Enqueue reference objects in parallel"), 3975 _enq_task(enq_task) 3976 { } 3977 3978 virtual void work(uint worker_id) { 3979 _enq_task.work(worker_id); 3980 } 3981 }; 3982 3983 // Driver routine for parallel reference enqueueing. 3984 // Creates an instance of the ref enqueueing gang 3985 // task and has the worker threads execute it. 3986 3987 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) { 3988 assert(_workers != NULL, "Need parallel worker threads."); 3989 3990 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task); 3991 3992 _workers->run_task(&enq_task_proxy); 3993 } 3994 3995 // End of weak reference support closures 3996 3997 // Abstract task used to preserve (i.e. copy) any referent objects 3998 // that are in the collection set and are pointed to by reference 3999 // objects discovered by the CM ref processor. 4000 4001 class G1ParPreserveCMReferentsTask: public AbstractGangTask { 4002 protected: 4003 G1CollectedHeap* _g1h; 4004 G1ParScanThreadStateSet* _pss; 4005 RefToScanQueueSet* _queues; 4006 ParallelTaskTerminator _terminator; 4007 uint _n_workers; 4008 4009 public: 4010 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) : 4011 AbstractGangTask("ParPreserveCMReferents"), 4012 _g1h(g1h), 4013 _pss(per_thread_states), 4014 _queues(task_queues), 4015 _terminator(workers, _queues), 4016 _n_workers(workers) 4017 { 4018 g1h->ref_processor_cm()->set_active_mt_degree(workers); 4019 } 4020 4021 void work(uint worker_id) { 4022 G1GCParPhaseTimesTracker x(_g1h->g1_policy()->phase_times(), G1GCPhaseTimes::PreserveCMReferents, worker_id); 4023 4024 ResourceMark rm; 4025 HandleMark hm; 4026 4027 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 4028 pss->set_ref_processor(NULL); 4029 assert(pss->queue_is_empty(), "both queue and overflow should be empty"); 4030 4031 // Is alive closure 4032 G1AlwaysAliveClosure always_alive(_g1h); 4033 4034 // Copying keep alive closure. Applied to referent objects that need 4035 // to be copied. 4036 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss); 4037 4038 ReferenceProcessor* rp = _g1h->ref_processor_cm(); 4039 4040 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q(); 4041 uint stride = MIN2(MAX2(_n_workers, 1U), limit); 4042 4043 // limit is set using max_num_q() - which was set using ParallelGCThreads. 4044 // So this must be true - but assert just in case someone decides to 4045 // change the worker ids. 4046 assert(worker_id < limit, "sanity"); 4047 assert(!rp->discovery_is_atomic(), "check this code"); 4048 4049 // Select discovered lists [i, i+stride, i+2*stride,...,limit) 4050 for (uint idx = worker_id; idx < limit; idx += stride) { 4051 DiscoveredList& ref_list = rp->discovered_refs()[idx]; 4052 4053 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive); 4054 while (iter.has_next()) { 4055 // Since discovery is not atomic for the CM ref processor, we 4056 // can see some null referent objects. 4057 iter.load_ptrs(DEBUG_ONLY(true)); 4058 oop ref = iter.obj(); 4059 4060 // This will filter nulls. 4061 if (iter.is_referent_alive()) { 4062 iter.make_referent_alive(); 4063 } 4064 iter.move_to_next(); 4065 } 4066 } 4067 4068 // Drain the queue - which may cause stealing 4069 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator); 4070 drain_queue.do_void(); 4071 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure 4072 assert(pss->queue_is_empty(), "should be"); 4073 } 4074 }; 4075 4076 void G1CollectedHeap::preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states) { 4077 // Any reference objects, in the collection set, that were 'discovered' 4078 // by the CM ref processor should have already been copied (either by 4079 // applying the external root copy closure to the discovered lists, or 4080 // by following an RSet entry). 4081 // 4082 // But some of the referents, that are in the collection set, that these 4083 // reference objects point to may not have been copied: the STW ref 4084 // processor would have seen that the reference object had already 4085 // been 'discovered' and would have skipped discovering the reference, 4086 // but would not have treated the reference object as a regular oop. 4087 // As a result the copy closure would not have been applied to the 4088 // referent object. 4089 // 4090 // We need to explicitly copy these referent objects - the references 4091 // will be processed at the end of remarking. 4092 // 4093 // We also need to do this copying before we process the reference 4094 // objects discovered by the STW ref processor in case one of these 4095 // referents points to another object which is also referenced by an 4096 // object discovered by the STW ref processor. 4097 double preserve_cm_referents_time = 0.0; 4098 4099 // To avoid spawning task when there is no work to do, check that 4100 // a concurrent cycle is active and that some references have been 4101 // discovered. 4102 if (concurrent_mark()->cm_thread()->during_cycle() && 4103 ref_processor_cm()->has_discovered_references()) { 4104 double preserve_cm_referents_start = os::elapsedTime(); 4105 uint no_of_gc_workers = workers()->active_workers(); 4106 G1ParPreserveCMReferentsTask keep_cm_referents(this, 4107 per_thread_states, 4108 no_of_gc_workers, 4109 _task_queues); 4110 workers()->run_task(&keep_cm_referents); 4111 preserve_cm_referents_time = os::elapsedTime() - preserve_cm_referents_start; 4112 } 4113 4114 g1_policy()->phase_times()->record_preserve_cm_referents_time_ms(preserve_cm_referents_time * 1000.0); 4115 } 4116 4117 // Weak Reference processing during an evacuation pause (part 1). 4118 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) { 4119 double ref_proc_start = os::elapsedTime(); 4120 4121 ReferenceProcessor* rp = _ref_processor_stw; 4122 assert(rp->discovery_enabled(), "should have been enabled"); 4123 4124 // Closure to test whether a referent is alive. 4125 G1STWIsAliveClosure is_alive(this); 4126 4127 // Even when parallel reference processing is enabled, the processing 4128 // of JNI refs is serial and performed serially by the current thread 4129 // rather than by a worker. The following PSS will be used for processing 4130 // JNI refs. 4131 4132 // Use only a single queue for this PSS. 4133 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0); 4134 pss->set_ref_processor(NULL); 4135 assert(pss->queue_is_empty(), "pre-condition"); 4136 4137 // Keep alive closure. 4138 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss); 4139 4140 // Serial Complete GC closure 4141 G1STWDrainQueueClosure drain_queue(this, pss); 4142 4143 // Setup the soft refs policy... 4144 rp->setup_policy(false); 4145 4146 ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times(); 4147 4148 ReferenceProcessorStats stats; 4149 if (!rp->processing_is_mt()) { 4150 // Serial reference processing... 4151 stats = rp->process_discovered_references(&is_alive, 4152 &keep_alive, 4153 &drain_queue, 4154 NULL, 4155 pt); 4156 } else { 4157 uint no_of_gc_workers = workers()->active_workers(); 4158 4159 // Parallel reference processing 4160 assert(no_of_gc_workers <= rp->max_num_q(), 4161 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u", 4162 no_of_gc_workers, rp->max_num_q()); 4163 4164 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers); 4165 stats = rp->process_discovered_references(&is_alive, 4166 &keep_alive, 4167 &drain_queue, 4168 &par_task_executor, 4169 pt); 4170 } 4171 4172 _gc_tracer_stw->report_gc_reference_stats(stats); 4173 4174 // We have completed copying any necessary live referent objects. 4175 assert(pss->queue_is_empty(), "both queue and overflow should be empty"); 4176 4177 double ref_proc_time = os::elapsedTime() - ref_proc_start; 4178 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 4179 } 4180 4181 // Weak Reference processing during an evacuation pause (part 2). 4182 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) { 4183 double ref_enq_start = os::elapsedTime(); 4184 4185 ReferenceProcessor* rp = _ref_processor_stw; 4186 assert(!rp->discovery_enabled(), "should have been disabled as part of processing"); 4187 4188 ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times(); 4189 4190 // Now enqueue any remaining on the discovered lists on to 4191 // the pending list. 4192 if (!rp->processing_is_mt()) { 4193 // Serial reference processing... 4194 rp->enqueue_discovered_references(NULL, pt); 4195 } else { 4196 // Parallel reference enqueueing 4197 4198 uint n_workers = workers()->active_workers(); 4199 4200 assert(n_workers <= rp->max_num_q(), 4201 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u", 4202 n_workers, rp->max_num_q()); 4203 4204 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers); 4205 rp->enqueue_discovered_references(&par_task_executor, pt); 4206 } 4207 4208 rp->verify_no_references_recorded(); 4209 assert(!rp->discovery_enabled(), "should have been disabled"); 4210 4211 // If during an initial mark pause we install a pending list head which is not otherwise reachable 4212 // ensure that it is marked in the bitmap for concurrent marking to discover. 4213 if (collector_state()->during_initial_mark_pause()) { 4214 oop pll_head = Universe::reference_pending_list(); 4215 if (pll_head != NULL) { 4216 _cm->mark_in_next_bitmap(pll_head); 4217 } 4218 } 4219 4220 // FIXME 4221 // CM's reference processing also cleans up the string and symbol tables. 4222 // Should we do that here also? We could, but it is a serial operation 4223 // and could significantly increase the pause time. 4224 4225 double ref_enq_time = os::elapsedTime() - ref_enq_start; 4226 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0); 4227 } 4228 4229 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) { 4230 double merge_pss_time_start = os::elapsedTime(); 4231 per_thread_states->flush(); 4232 g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0); 4233 } 4234 4235 void G1CollectedHeap::pre_evacuate_collection_set() { 4236 _expand_heap_after_alloc_failure = true; 4237 _evacuation_failed = false; 4238 4239 // Disable the hot card cache. 4240 _hot_card_cache->reset_hot_cache_claimed_index(); 4241 _hot_card_cache->set_use_cache(false); 4242 4243 g1_rem_set()->prepare_for_oops_into_collection_set_do(); 4244 _preserved_marks_set.assert_empty(); 4245 4246 G1GCPhaseTimes* phase_times = g1_policy()->phase_times(); 4247 4248 // InitialMark needs claim bits to keep track of the marked-through CLDs. 4249 if (collector_state()->during_initial_mark_pause()) { 4250 double start_clear_claimed_marks = os::elapsedTime(); 4251 4252 ClassLoaderDataGraph::clear_claimed_marks(); 4253 4254 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0; 4255 phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms); 4256 } 4257 } 4258 4259 void G1CollectedHeap::evacuate_collection_set(G1ParScanThreadStateSet* per_thread_states) { 4260 // Should G1EvacuationFailureALot be in effect for this GC? 4261 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) 4262 4263 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty"); 4264 4265 G1GCPhaseTimes* phase_times = g1_policy()->phase_times(); 4266 4267 double start_par_time_sec = os::elapsedTime(); 4268 double end_par_time_sec; 4269 4270 { 4271 const uint n_workers = workers()->active_workers(); 4272 G1RootProcessor root_processor(this, n_workers); 4273 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers); 4274 4275 print_termination_stats_hdr(); 4276 4277 workers()->run_task(&g1_par_task); 4278 end_par_time_sec = os::elapsedTime(); 4279 4280 // Closing the inner scope will execute the destructor 4281 // for the G1RootProcessor object. We record the current 4282 // elapsed time before closing the scope so that time 4283 // taken for the destructor is NOT included in the 4284 // reported parallel time. 4285 } 4286 4287 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0; 4288 phase_times->record_par_time(par_time_ms); 4289 4290 double code_root_fixup_time_ms = 4291 (os::elapsedTime() - end_par_time_sec) * 1000.0; 4292 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms); 4293 } 4294 4295 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) { 4296 // Process any discovered reference objects - we have 4297 // to do this _before_ we retire the GC alloc regions 4298 // as we may have to copy some 'reachable' referent 4299 // objects (and their reachable sub-graphs) that were 4300 // not copied during the pause. 4301 if (g1_policy()->should_process_references()) { 4302 preserve_cm_referents(per_thread_states); 4303 process_discovered_references(per_thread_states); 4304 } else { 4305 ref_processor_stw()->verify_no_references_recorded(); 4306 } 4307 4308 G1STWIsAliveClosure is_alive(this); 4309 G1KeepAliveClosure keep_alive(this); 4310 4311 { 4312 double start = os::elapsedTime(); 4313 4314 WeakProcessor::weak_oops_do(&is_alive, &keep_alive); 4315 4316 double time_ms = (os::elapsedTime() - start) * 1000.0; 4317 g1_policy()->phase_times()->record_ref_proc_time(time_ms); 4318 } 4319 4320 if (G1StringDedup::is_enabled()) { 4321 double fixup_start = os::elapsedTime(); 4322 4323 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times()); 4324 4325 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0; 4326 g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms); 4327 } 4328 4329 g1_rem_set()->cleanup_after_oops_into_collection_set_do(); 4330 4331 if (evacuation_failed()) { 4332 restore_after_evac_failure(); 4333 4334 // Reset the G1EvacuationFailureALot counters and flags 4335 // Note: the values are reset only when an actual 4336 // evacuation failure occurs. 4337 NOT_PRODUCT(reset_evacuation_should_fail();) 4338 } 4339 4340 _preserved_marks_set.assert_empty(); 4341 4342 // Enqueue any remaining references remaining on the STW 4343 // reference processor's discovered lists. We need to do 4344 // this after the card table is cleaned (and verified) as 4345 // the act of enqueueing entries on to the pending list 4346 // will log these updates (and dirty their associated 4347 // cards). We need these updates logged to update any 4348 // RSets. 4349 if (g1_policy()->should_process_references()) { 4350 enqueue_discovered_references(per_thread_states); 4351 } else { 4352 g1_policy()->phase_times()->record_ref_enq_time(0); 4353 } 4354 4355 _allocator->release_gc_alloc_regions(evacuation_info); 4356 4357 merge_per_thread_state_info(per_thread_states); 4358 4359 // Reset and re-enable the hot card cache. 4360 // Note the counts for the cards in the regions in the 4361 // collection set are reset when the collection set is freed. 4362 _hot_card_cache->reset_hot_cache(); 4363 _hot_card_cache->set_use_cache(true); 4364 4365 purge_code_root_memory(); 4366 4367 redirty_logged_cards(); 4368 #if COMPILER2_OR_JVMCI 4369 double start = os::elapsedTime(); 4370 DerivedPointerTable::update_pointers(); 4371 g1_policy()->phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0); 4372 #endif 4373 g1_policy()->print_age_table(); 4374 } 4375 4376 void G1CollectedHeap::record_obj_copy_mem_stats() { 4377 g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize); 4378 4379 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats), 4380 create_g1_evac_summary(&_old_evac_stats)); 4381 } 4382 4383 void G1CollectedHeap::free_region(HeapRegion* hr, 4384 FreeRegionList* free_list, 4385 bool skip_remset, 4386 bool skip_hot_card_cache, 4387 bool locked) { 4388 assert(!hr->is_free(), "the region should not be free"); 4389 assert(!hr->is_empty(), "the region should not be empty"); 4390 assert(_hrm.is_available(hr->hrm_index()), "region should be committed"); 4391 assert(free_list != NULL, "pre-condition"); 4392 4393 if (G1VerifyBitmaps) { 4394 MemRegion mr(hr->bottom(), hr->end()); 4395 concurrent_mark()->clear_range_in_prev_bitmap(mr); 4396 } 4397 4398 // Clear the card counts for this region. 4399 // Note: we only need to do this if the region is not young 4400 // (since we don't refine cards in young regions). 4401 if (!skip_hot_card_cache && !hr->is_young()) { 4402 _hot_card_cache->reset_card_counts(hr); 4403 } 4404 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */); 4405 free_list->add_ordered(hr); 4406 } 4407 4408 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 4409 FreeRegionList* free_list, 4410 bool skip_remset) { 4411 assert(hr->is_humongous(), "this is only for humongous regions"); 4412 assert(free_list != NULL, "pre-condition"); 4413 hr->clear_humongous(); 4414 free_region(hr, free_list, skip_remset); 4415 } 4416 4417 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed, 4418 const uint humongous_regions_removed) { 4419 if (old_regions_removed > 0 || humongous_regions_removed > 0) { 4420 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 4421 _old_set.bulk_remove(old_regions_removed); 4422 _humongous_set.bulk_remove(humongous_regions_removed); 4423 } 4424 4425 } 4426 4427 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) { 4428 assert(list != NULL, "list can't be null"); 4429 if (!list->is_empty()) { 4430 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag); 4431 _hrm.insert_list_into_free_list(list); 4432 } 4433 } 4434 4435 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) { 4436 decrease_used(bytes); 4437 } 4438 4439 class G1ParScrubRemSetTask: public AbstractGangTask { 4440 protected: 4441 G1RemSet* _g1rs; 4442 HeapRegionClaimer _hrclaimer; 4443 4444 public: 4445 G1ParScrubRemSetTask(G1RemSet* g1_rs, uint num_workers) : 4446 AbstractGangTask("G1 ScrubRS"), 4447 _g1rs(g1_rs), 4448 _hrclaimer(num_workers) { 4449 } 4450 4451 void work(uint worker_id) { 4452 _g1rs->scrub(worker_id, &_hrclaimer); 4453 } 4454 }; 4455 4456 void G1CollectedHeap::scrub_rem_set() { 4457 uint num_workers = workers()->active_workers(); 4458 G1ParScrubRemSetTask g1_par_scrub_rs_task(g1_rem_set(), num_workers); 4459 workers()->run_task(&g1_par_scrub_rs_task); 4460 } 4461 4462 class G1FreeCollectionSetTask : public AbstractGangTask { 4463 private: 4464 4465 // Closure applied to all regions in the collection set to do work that needs to 4466 // be done serially in a single thread. 4467 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure { 4468 private: 4469 EvacuationInfo* _evacuation_info; 4470 const size_t* _surviving_young_words; 4471 4472 // Bytes used in successfully evacuated regions before the evacuation. 4473 size_t _before_used_bytes; 4474 // Bytes used in unsucessfully evacuated regions before the evacuation 4475 size_t _after_used_bytes; 4476 4477 size_t _bytes_allocated_in_old_since_last_gc; 4478 4479 size_t _failure_used_words; 4480 size_t _failure_waste_words; 4481 4482 FreeRegionList _local_free_list; 4483 public: 4484 G1SerialFreeCollectionSetClosure(EvacuationInfo* evacuation_info, const size_t* surviving_young_words) : 4485 HeapRegionClosure(), 4486 _evacuation_info(evacuation_info), 4487 _surviving_young_words(surviving_young_words), 4488 _before_used_bytes(0), 4489 _after_used_bytes(0), 4490 _bytes_allocated_in_old_since_last_gc(0), 4491 _failure_used_words(0), 4492 _failure_waste_words(0), 4493 _local_free_list("Local Region List for CSet Freeing") { 4494 } 4495 4496 virtual bool do_heap_region(HeapRegion* r) { 4497 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4498 4499 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index()); 4500 g1h->clear_in_cset(r); 4501 4502 if (r->is_young()) { 4503 assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(), 4504 "Young index %d is wrong for region %u of type %s with %u young regions", 4505 r->young_index_in_cset(), 4506 r->hrm_index(), 4507 r->get_type_str(), 4508 g1h->collection_set()->young_region_length()); 4509 size_t words_survived = _surviving_young_words[r->young_index_in_cset()]; 4510 r->record_surv_words_in_group(words_survived); 4511 } 4512 4513 if (!r->evacuation_failed()) { 4514 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index()); 4515 _before_used_bytes += r->used(); 4516 g1h->free_region(r, 4517 &_local_free_list, 4518 true, /* skip_remset */ 4519 true, /* skip_hot_card_cache */ 4520 true /* locked */); 4521 } else { 4522 r->uninstall_surv_rate_group(); 4523 r->set_young_index_in_cset(-1); 4524 r->set_evacuation_failed(false); 4525 // When moving a young gen region to old gen, we "allocate" that whole region 4526 // there. This is in addition to any already evacuated objects. Notify the 4527 // policy about that. 4528 // Old gen regions do not cause an additional allocation: both the objects 4529 // still in the region and the ones already moved are accounted for elsewhere. 4530 if (r->is_young()) { 4531 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes; 4532 } 4533 // The region is now considered to be old. 4534 r->set_old(); 4535 // Do some allocation statistics accounting. Regions that failed evacuation 4536 // are always made old, so there is no need to update anything in the young 4537 // gen statistics, but we need to update old gen statistics. 4538 size_t used_words = r->marked_bytes() / HeapWordSize; 4539 4540 _failure_used_words += used_words; 4541 _failure_waste_words += HeapRegion::GrainWords - used_words; 4542 4543 g1h->old_set_add(r); 4544 _after_used_bytes += r->used(); 4545 } 4546 return false; 4547 } 4548 4549 void complete_work() { 4550 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4551 4552 _evacuation_info->set_regions_freed(_local_free_list.length()); 4553 _evacuation_info->increment_collectionset_used_after(_after_used_bytes); 4554 4555 g1h->prepend_to_freelist(&_local_free_list); 4556 g1h->decrement_summary_bytes(_before_used_bytes); 4557 4558 G1Policy* policy = g1h->g1_policy(); 4559 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc); 4560 4561 g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words); 4562 } 4563 }; 4564 4565 G1CollectionSet* _collection_set; 4566 G1SerialFreeCollectionSetClosure _cl; 4567 const size_t* _surviving_young_words; 4568 4569 size_t _rs_lengths; 4570 4571 volatile jint _serial_work_claim; 4572 4573 struct WorkItem { 4574 uint region_idx; 4575 bool is_young; 4576 bool evacuation_failed; 4577 4578 WorkItem(HeapRegion* r) { 4579 region_idx = r->hrm_index(); 4580 is_young = r->is_young(); 4581 evacuation_failed = r->evacuation_failed(); 4582 } 4583 }; 4584 4585 volatile size_t _parallel_work_claim; 4586 size_t _num_work_items; 4587 WorkItem* _work_items; 4588 4589 void do_serial_work() { 4590 // Need to grab the lock to be allowed to modify the old region list. 4591 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 4592 _collection_set->iterate(&_cl); 4593 } 4594 4595 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) { 4596 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4597 4598 HeapRegion* r = g1h->region_at(region_idx); 4599 assert(!g1h->is_on_master_free_list(r), "sanity"); 4600 4601 Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths); 4602 4603 if (!is_young) { 4604 g1h->_hot_card_cache->reset_card_counts(r); 4605 } 4606 4607 if (!evacuation_failed) { 4608 r->rem_set()->clear_locked(); 4609 } 4610 } 4611 4612 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure { 4613 private: 4614 size_t _cur_idx; 4615 WorkItem* _work_items; 4616 public: 4617 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { } 4618 4619 virtual bool do_heap_region(HeapRegion* r) { 4620 _work_items[_cur_idx++] = WorkItem(r); 4621 return false; 4622 } 4623 }; 4624 4625 void prepare_work() { 4626 G1PrepareFreeCollectionSetClosure cl(_work_items); 4627 _collection_set->iterate(&cl); 4628 } 4629 4630 void complete_work() { 4631 _cl.complete_work(); 4632 4633 G1Policy* policy = G1CollectedHeap::heap()->g1_policy(); 4634 policy->record_max_rs_lengths(_rs_lengths); 4635 policy->cset_regions_freed(); 4636 } 4637 public: 4638 G1FreeCollectionSetTask(G1CollectionSet* collection_set, EvacuationInfo* evacuation_info, const size_t* surviving_young_words) : 4639 AbstractGangTask("G1 Free Collection Set"), 4640 _cl(evacuation_info, surviving_young_words), 4641 _collection_set(collection_set), 4642 _surviving_young_words(surviving_young_words), 4643 _serial_work_claim(0), 4644 _rs_lengths(0), 4645 _parallel_work_claim(0), 4646 _num_work_items(collection_set->region_length()), 4647 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) { 4648 prepare_work(); 4649 } 4650 4651 ~G1FreeCollectionSetTask() { 4652 complete_work(); 4653 FREE_C_HEAP_ARRAY(WorkItem, _work_items); 4654 } 4655 4656 // Chunk size for work distribution. The chosen value has been determined experimentally 4657 // to be a good tradeoff between overhead and achievable parallelism. 4658 static uint chunk_size() { return 32; } 4659 4660 virtual void work(uint worker_id) { 4661 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times(); 4662 4663 // Claim serial work. 4664 if (_serial_work_claim == 0) { 4665 jint value = Atomic::add(1, &_serial_work_claim) - 1; 4666 if (value == 0) { 4667 double serial_time = os::elapsedTime(); 4668 do_serial_work(); 4669 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0); 4670 } 4671 } 4672 4673 // Start parallel work. 4674 double young_time = 0.0; 4675 bool has_young_time = false; 4676 double non_young_time = 0.0; 4677 bool has_non_young_time = false; 4678 4679 while (true) { 4680 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim); 4681 size_t cur = end - chunk_size(); 4682 4683 if (cur >= _num_work_items) { 4684 break; 4685 } 4686 4687 double start_time = os::elapsedTime(); 4688 4689 end = MIN2(end, _num_work_items); 4690 4691 for (; cur < end; cur++) { 4692 bool is_young = _work_items[cur].is_young; 4693 4694 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed); 4695 4696 double end_time = os::elapsedTime(); 4697 double time_taken = end_time - start_time; 4698 if (is_young) { 4699 young_time += time_taken; 4700 has_young_time = true; 4701 } else { 4702 non_young_time += time_taken; 4703 has_non_young_time = true; 4704 } 4705 start_time = end_time; 4706 } 4707 } 4708 4709 if (has_young_time) { 4710 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time); 4711 } 4712 if (has_non_young_time) { 4713 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time); 4714 } 4715 } 4716 }; 4717 4718 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) { 4719 _eden.clear(); 4720 4721 double free_cset_start_time = os::elapsedTime(); 4722 4723 { 4724 uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U); 4725 uint const num_workers = MIN2(workers()->active_workers(), num_chunks); 4726 4727 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words); 4728 4729 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u", 4730 cl.name(), 4731 num_workers, 4732 _collection_set.region_length()); 4733 workers()->run_task(&cl, num_workers); 4734 } 4735 g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0); 4736 4737 collection_set->clear(); 4738 } 4739 4740 class G1FreeHumongousRegionClosure : public HeapRegionClosure { 4741 private: 4742 FreeRegionList* _free_region_list; 4743 HeapRegionSet* _proxy_set; 4744 uint _humongous_objects_reclaimed; 4745 uint _humongous_regions_reclaimed; 4746 size_t _freed_bytes; 4747 public: 4748 4749 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) : 4750 _free_region_list(free_region_list), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) { 4751 } 4752 4753 virtual bool do_heap_region(HeapRegion* r) { 4754 if (!r->is_starts_humongous()) { 4755 return false; 4756 } 4757 4758 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4759 4760 oop obj = (oop)r->bottom(); 4761 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap(); 4762 4763 // The following checks whether the humongous object is live are sufficient. 4764 // The main additional check (in addition to having a reference from the roots 4765 // or the young gen) is whether the humongous object has a remembered set entry. 4766 // 4767 // A humongous object cannot be live if there is no remembered set for it 4768 // because: 4769 // - there can be no references from within humongous starts regions referencing 4770 // the object because we never allocate other objects into them. 4771 // (I.e. there are no intra-region references that may be missed by the 4772 // remembered set) 4773 // - as soon there is a remembered set entry to the humongous starts region 4774 // (i.e. it has "escaped" to an old object) this remembered set entry will stay 4775 // until the end of a concurrent mark. 4776 // 4777 // It is not required to check whether the object has been found dead by marking 4778 // or not, in fact it would prevent reclamation within a concurrent cycle, as 4779 // all objects allocated during that time are considered live. 4780 // SATB marking is even more conservative than the remembered set. 4781 // So if at this point in the collection there is no remembered set entry, 4782 // nobody has a reference to it. 4783 // At the start of collection we flush all refinement logs, and remembered sets 4784 // are completely up-to-date wrt to references to the humongous object. 4785 // 4786 // Other implementation considerations: 4787 // - never consider object arrays at this time because they would pose 4788 // considerable effort for cleaning up the the remembered sets. This is 4789 // required because stale remembered sets might reference locations that 4790 // are currently allocated into. 4791 uint region_idx = r->hrm_index(); 4792 if (!g1h->is_humongous_reclaim_candidate(region_idx) || 4793 !r->rem_set()->is_empty()) { 4794 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", 4795 region_idx, 4796 (size_t)obj->size() * HeapWordSize, 4797 p2i(r->bottom()), 4798 r->rem_set()->occupied(), 4799 r->rem_set()->strong_code_roots_list_length(), 4800 next_bitmap->is_marked(r->bottom()), 4801 g1h->is_humongous_reclaim_candidate(region_idx), 4802 obj->is_typeArray() 4803 ); 4804 return false; 4805 } 4806 4807 guarantee(obj->is_typeArray(), 4808 "Only eagerly reclaiming type arrays is supported, but the object " 4809 PTR_FORMAT " is not.", p2i(r->bottom())); 4810 4811 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", 4812 region_idx, 4813 (size_t)obj->size() * HeapWordSize, 4814 p2i(r->bottom()), 4815 r->rem_set()->occupied(), 4816 r->rem_set()->strong_code_roots_list_length(), 4817 next_bitmap->is_marked(r->bottom()), 4818 g1h->is_humongous_reclaim_candidate(region_idx), 4819 obj->is_typeArray() 4820 ); 4821 4822 g1h->concurrent_mark()->humongous_object_eagerly_reclaimed(r); 4823 _humongous_objects_reclaimed++; 4824 do { 4825 HeapRegion* next = g1h->next_region_in_humongous(r); 4826 _freed_bytes += r->used(); 4827 r->set_containing_set(NULL); 4828 _humongous_regions_reclaimed++; 4829 g1h->free_humongous_region(r, _free_region_list, false /* skip_remset */ ); 4830 r = next; 4831 } while (r != NULL); 4832 4833 return false; 4834 } 4835 4836 uint humongous_objects_reclaimed() { 4837 return _humongous_objects_reclaimed; 4838 } 4839 4840 uint humongous_regions_reclaimed() { 4841 return _humongous_regions_reclaimed; 4842 } 4843 4844 size_t bytes_freed() const { 4845 return _freed_bytes; 4846 } 4847 }; 4848 4849 void G1CollectedHeap::eagerly_reclaim_humongous_regions() { 4850 assert_at_safepoint_on_vm_thread(); 4851 4852 if (!G1EagerReclaimHumongousObjects || 4853 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) { 4854 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0); 4855 return; 4856 } 4857 4858 double start_time = os::elapsedTime(); 4859 4860 FreeRegionList local_cleanup_list("Local Humongous Cleanup List"); 4861 4862 G1FreeHumongousRegionClosure cl(&local_cleanup_list); 4863 heap_region_iterate(&cl); 4864 4865 remove_from_old_sets(0, cl.humongous_regions_reclaimed()); 4866 4867 G1HRPrinter* hrp = hr_printer(); 4868 if (hrp->is_active()) { 4869 FreeRegionListIterator iter(&local_cleanup_list); 4870 while (iter.more_available()) { 4871 HeapRegion* hr = iter.get_next(); 4872 hrp->cleanup(hr); 4873 } 4874 } 4875 4876 prepend_to_freelist(&local_cleanup_list); 4877 decrement_summary_bytes(cl.bytes_freed()); 4878 4879 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0, 4880 cl.humongous_objects_reclaimed()); 4881 } 4882 4883 class G1AbandonCollectionSetClosure : public HeapRegionClosure { 4884 public: 4885 virtual bool do_heap_region(HeapRegion* r) { 4886 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index()); 4887 G1CollectedHeap::heap()->clear_in_cset(r); 4888 r->set_young_index_in_cset(-1); 4889 return false; 4890 } 4891 }; 4892 4893 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) { 4894 G1AbandonCollectionSetClosure cl; 4895 collection_set->iterate(&cl); 4896 4897 collection_set->clear(); 4898 collection_set->stop_incremental_building(); 4899 } 4900 4901 void G1CollectedHeap::set_free_regions_coming() { 4902 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : setting free regions coming"); 4903 4904 assert(!free_regions_coming(), "pre-condition"); 4905 _free_regions_coming = true; 4906 } 4907 4908 void G1CollectedHeap::reset_free_regions_coming() { 4909 assert(free_regions_coming(), "pre-condition"); 4910 4911 { 4912 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 4913 _free_regions_coming = false; 4914 SecondaryFreeList_lock->notify_all(); 4915 } 4916 4917 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : reset free regions coming"); 4918 } 4919 4920 void G1CollectedHeap::wait_while_free_regions_coming() { 4921 // Most of the time we won't have to wait, so let's do a quick test 4922 // first before we take the lock. 4923 if (!free_regions_coming()) { 4924 return; 4925 } 4926 4927 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : waiting for free regions"); 4928 4929 { 4930 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 4931 while (free_regions_coming()) { 4932 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 4933 } 4934 } 4935 4936 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : done waiting for free regions"); 4937 } 4938 4939 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) { 4940 return _allocator->is_retained_old_region(hr); 4941 } 4942 4943 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 4944 _eden.add(hr); 4945 _g1_policy->set_region_eden(hr); 4946 } 4947 4948 #ifdef ASSERT 4949 4950 class NoYoungRegionsClosure: public HeapRegionClosure { 4951 private: 4952 bool _success; 4953 public: 4954 NoYoungRegionsClosure() : _success(true) { } 4955 bool do_heap_region(HeapRegion* r) { 4956 if (r->is_young()) { 4957 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young", 4958 p2i(r->bottom()), p2i(r->end())); 4959 _success = false; 4960 } 4961 return false; 4962 } 4963 bool success() { return _success; } 4964 }; 4965 4966 bool G1CollectedHeap::check_young_list_empty() { 4967 bool ret = (young_regions_count() == 0); 4968 4969 NoYoungRegionsClosure closure; 4970 heap_region_iterate(&closure); 4971 ret = ret && closure.success(); 4972 4973 return ret; 4974 } 4975 4976 #endif // ASSERT 4977 4978 class TearDownRegionSetsClosure : public HeapRegionClosure { 4979 private: 4980 HeapRegionSet *_old_set; 4981 4982 public: 4983 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { } 4984 4985 bool do_heap_region(HeapRegion* r) { 4986 if (r->is_old()) { 4987 _old_set->remove(r); 4988 } else if(r->is_young()) { 4989 r->uninstall_surv_rate_group(); 4990 } else { 4991 // We ignore free regions, we'll empty the free list afterwards. 4992 // We ignore humongous regions, we're not tearing down the 4993 // humongous regions set. 4994 assert(r->is_free() || r->is_humongous(), 4995 "it cannot be another type"); 4996 } 4997 return false; 4998 } 4999 5000 ~TearDownRegionSetsClosure() { 5001 assert(_old_set->is_empty(), "post-condition"); 5002 } 5003 }; 5004 5005 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) { 5006 assert_at_safepoint_on_vm_thread(); 5007 5008 if (!free_list_only) { 5009 TearDownRegionSetsClosure cl(&_old_set); 5010 heap_region_iterate(&cl); 5011 5012 // Note that emptying the _young_list is postponed and instead done as 5013 // the first step when rebuilding the regions sets again. The reason for 5014 // this is that during a full GC string deduplication needs to know if 5015 // a collected region was young or old when the full GC was initiated. 5016 } 5017 _hrm.remove_all_free_regions(); 5018 } 5019 5020 void G1CollectedHeap::increase_used(size_t bytes) { 5021 _summary_bytes_used += bytes; 5022 } 5023 5024 void G1CollectedHeap::decrease_used(size_t bytes) { 5025 assert(_summary_bytes_used >= bytes, 5026 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT, 5027 _summary_bytes_used, bytes); 5028 _summary_bytes_used -= bytes; 5029 } 5030 5031 void G1CollectedHeap::set_used(size_t bytes) { 5032 _summary_bytes_used = bytes; 5033 } 5034 5035 class RebuildRegionSetsClosure : public HeapRegionClosure { 5036 private: 5037 bool _free_list_only; 5038 HeapRegionSet* _old_set; 5039 HeapRegionManager* _hrm; 5040 size_t _total_used; 5041 5042 public: 5043 RebuildRegionSetsClosure(bool free_list_only, 5044 HeapRegionSet* old_set, HeapRegionManager* hrm) : 5045 _free_list_only(free_list_only), 5046 _old_set(old_set), _hrm(hrm), _total_used(0) { 5047 assert(_hrm->num_free_regions() == 0, "pre-condition"); 5048 if (!free_list_only) { 5049 assert(_old_set->is_empty(), "pre-condition"); 5050 } 5051 } 5052 5053 bool do_heap_region(HeapRegion* r) { 5054 if (r->is_empty()) { 5055 // Add free regions to the free list 5056 r->set_free(); 5057 _hrm->insert_into_free_list(r); 5058 } else if (!_free_list_only) { 5059 5060 if (r->is_humongous()) { 5061 // We ignore humongous regions. We left the humongous set unchanged. 5062 } else { 5063 assert(r->is_young() || r->is_free() || r->is_old(), "invariant"); 5064 // We now move all (non-humongous, non-old) regions to old gen, and register them as such. 5065 r->move_to_old(); 5066 _old_set->add(r); 5067 } 5068 _total_used += r->used(); 5069 } 5070 5071 return false; 5072 } 5073 5074 size_t total_used() { 5075 return _total_used; 5076 } 5077 }; 5078 5079 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { 5080 assert_at_safepoint_on_vm_thread(); 5081 5082 if (!free_list_only) { 5083 _eden.clear(); 5084 _survivor.clear(); 5085 } 5086 5087 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm); 5088 heap_region_iterate(&cl); 5089 5090 if (!free_list_only) { 5091 set_used(cl.total_used()); 5092 if (_archive_allocator != NULL) { 5093 _archive_allocator->clear_used(); 5094 } 5095 } 5096 assert(used_unlocked() == recalculate_used(), 5097 "inconsistent used_unlocked(), " 5098 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT, 5099 used_unlocked(), recalculate_used()); 5100 } 5101 5102 bool G1CollectedHeap::is_in_closed_subset(const void* p) const { 5103 HeapRegion* hr = heap_region_containing(p); 5104 return hr->is_in(p); 5105 } 5106 5107 // Methods for the mutator alloc region 5108 5109 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 5110 bool force) { 5111 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 5112 bool should_allocate = g1_policy()->should_allocate_mutator_region(); 5113 if (force || should_allocate) { 5114 HeapRegion* new_alloc_region = new_region(word_size, 5115 false /* is_old */, 5116 false /* do_expand */); 5117 if (new_alloc_region != NULL) { 5118 set_region_short_lived_locked(new_alloc_region); 5119 _hr_printer.alloc(new_alloc_region, !should_allocate); 5120 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region); 5121 return new_alloc_region; 5122 } 5123 } 5124 return NULL; 5125 } 5126 5127 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 5128 size_t allocated_bytes) { 5129 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 5130 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden"); 5131 5132 collection_set()->add_eden_region(alloc_region); 5133 increase_used(allocated_bytes); 5134 _hr_printer.retire(alloc_region); 5135 // We update the eden sizes here, when the region is retired, 5136 // instead of when it's allocated, since this is the point that its 5137 // used space has been recored in _summary_bytes_used. 5138 g1mm()->update_eden_size(); 5139 } 5140 5141 // Methods for the GC alloc regions 5142 5143 bool G1CollectedHeap::has_more_regions(InCSetState dest) { 5144 if (dest.is_old()) { 5145 return true; 5146 } else { 5147 return survivor_regions_count() < g1_policy()->max_survivor_regions(); 5148 } 5149 } 5150 5151 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) { 5152 assert(FreeList_lock->owned_by_self(), "pre-condition"); 5153 5154 if (!has_more_regions(dest)) { 5155 return NULL; 5156 } 5157 5158 const bool is_survivor = dest.is_young(); 5159 5160 HeapRegion* new_alloc_region = new_region(word_size, 5161 !is_survivor, 5162 true /* do_expand */); 5163 if (new_alloc_region != NULL) { 5164 // We really only need to do this for old regions given that we 5165 // should never scan survivors. But it doesn't hurt to do it 5166 // for survivors too. 5167 new_alloc_region->record_timestamp(); 5168 if (is_survivor) { 5169 new_alloc_region->set_survivor(); 5170 _survivor.add(new_alloc_region); 5171 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region); 5172 } else { 5173 new_alloc_region->set_old(); 5174 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region); 5175 } 5176 _hr_printer.alloc(new_alloc_region); 5177 bool during_im = collector_state()->during_initial_mark_pause(); 5178 new_alloc_region->note_start_of_copying(during_im); 5179 return new_alloc_region; 5180 } 5181 return NULL; 5182 } 5183 5184 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 5185 size_t allocated_bytes, 5186 InCSetState dest) { 5187 bool during_im = collector_state()->during_initial_mark_pause(); 5188 alloc_region->note_end_of_copying(during_im); 5189 g1_policy()->record_bytes_copied_during_gc(allocated_bytes); 5190 if (dest.is_old()) { 5191 _old_set.add(alloc_region); 5192 } 5193 _hr_printer.retire(alloc_region); 5194 } 5195 5196 HeapRegion* G1CollectedHeap::alloc_highest_free_region() { 5197 bool expanded = false; 5198 uint index = _hrm.find_highest_free(&expanded); 5199 5200 if (index != G1_NO_HRM_INDEX) { 5201 if (expanded) { 5202 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B", 5203 HeapRegion::GrainWords * HeapWordSize); 5204 } 5205 _hrm.allocate_free_regions_starting_at(index, 1); 5206 return region_at(index); 5207 } 5208 return NULL; 5209 } 5210 5211 // Optimized nmethod scanning 5212 5213 class RegisterNMethodOopClosure: public OopClosure { 5214 G1CollectedHeap* _g1h; 5215 nmethod* _nm; 5216 5217 template <class T> void do_oop_work(T* p) { 5218 T heap_oop = oopDesc::load_heap_oop(p); 5219 if (!oopDesc::is_null(heap_oop)) { 5220 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 5221 HeapRegion* hr = _g1h->heap_region_containing(obj); 5222 assert(!hr->is_continues_humongous(), 5223 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 5224 " starting at " HR_FORMAT, 5225 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 5226 5227 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries. 5228 hr->add_strong_code_root_locked(_nm); 5229 } 5230 } 5231 5232 public: 5233 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 5234 _g1h(g1h), _nm(nm) {} 5235 5236 void do_oop(oop* p) { do_oop_work(p); } 5237 void do_oop(narrowOop* p) { do_oop_work(p); } 5238 }; 5239 5240 class UnregisterNMethodOopClosure: public OopClosure { 5241 G1CollectedHeap* _g1h; 5242 nmethod* _nm; 5243 5244 template <class T> void do_oop_work(T* p) { 5245 T heap_oop = oopDesc::load_heap_oop(p); 5246 if (!oopDesc::is_null(heap_oop)) { 5247 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 5248 HeapRegion* hr = _g1h->heap_region_containing(obj); 5249 assert(!hr->is_continues_humongous(), 5250 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 5251 " starting at " HR_FORMAT, 5252 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 5253 5254 hr->remove_strong_code_root(_nm); 5255 } 5256 } 5257 5258 public: 5259 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 5260 _g1h(g1h), _nm(nm) {} 5261 5262 void do_oop(oop* p) { do_oop_work(p); } 5263 void do_oop(narrowOop* p) { do_oop_work(p); } 5264 }; 5265 5266 // Returns true if the reference points to an object that 5267 // can move in an incremental collection. 5268 bool G1CollectedHeap::is_scavengable(oop obj) { 5269 HeapRegion* hr = heap_region_containing(obj); 5270 return !hr->is_pinned(); 5271 } 5272 5273 void G1CollectedHeap::register_nmethod(nmethod* nm) { 5274 guarantee(nm != NULL, "sanity"); 5275 RegisterNMethodOopClosure reg_cl(this, nm); 5276 nm->oops_do(®_cl); 5277 } 5278 5279 void G1CollectedHeap::unregister_nmethod(nmethod* nm) { 5280 guarantee(nm != NULL, "sanity"); 5281 UnregisterNMethodOopClosure reg_cl(this, nm); 5282 nm->oops_do(®_cl, true); 5283 } 5284 5285 void G1CollectedHeap::purge_code_root_memory() { 5286 double purge_start = os::elapsedTime(); 5287 G1CodeRootSet::purge(); 5288 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0; 5289 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms); 5290 } 5291 5292 class RebuildStrongCodeRootClosure: public CodeBlobClosure { 5293 G1CollectedHeap* _g1h; 5294 5295 public: 5296 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) : 5297 _g1h(g1h) {} 5298 5299 void do_code_blob(CodeBlob* cb) { 5300 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL; 5301 if (nm == NULL) { 5302 return; 5303 } 5304 5305 if (ScavengeRootsInCode) { 5306 _g1h->register_nmethod(nm); 5307 } 5308 } 5309 }; 5310 5311 void G1CollectedHeap::rebuild_strong_code_roots() { 5312 RebuildStrongCodeRootClosure blob_cl(this); 5313 CodeCache::blobs_do(&blob_cl); 5314 } 5315 5316 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() { 5317 GrowableArray<GCMemoryManager*> memory_managers(2); 5318 memory_managers.append(&_memory_manager); 5319 memory_managers.append(&_full_gc_memory_manager); 5320 return memory_managers; 5321 } 5322 5323 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() { 5324 GrowableArray<MemoryPool*> memory_pools(3); 5325 memory_pools.append(_eden_pool); 5326 memory_pools.append(_survivor_pool); 5327 memory_pools.append(_old_pool); 5328 return memory_pools; 5329 }