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/g1EvacStats.inline.hpp" 41 #include "gc/g1/g1FullCollector.hpp" 42 #include "gc/g1/g1GCPhaseTimes.hpp" 43 #include "gc/g1/g1HeapSizingPolicy.hpp" 44 #include "gc/g1/g1HeapTransition.hpp" 45 #include "gc/g1/g1HeapVerifier.hpp" 46 #include "gc/g1/g1HotCardCache.hpp" 47 #include "gc/g1/g1MemoryPool.hpp" 48 #include "gc/g1/g1OopClosures.inline.hpp" 49 #include "gc/g1/g1ParScanThreadState.inline.hpp" 50 #include "gc/g1/g1Policy.hpp" 51 #include "gc/g1/g1RegionToSpaceMapper.hpp" 52 #include "gc/g1/g1RemSet.hpp" 53 #include "gc/g1/g1RootClosures.hpp" 54 #include "gc/g1/g1RootProcessor.hpp" 55 #include "gc/g1/g1StringDedup.hpp" 56 #include "gc/g1/g1YCTypes.hpp" 57 #include "gc/g1/g1YoungRemSetSamplingThread.hpp" 58 #include "gc/g1/heapRegion.inline.hpp" 59 #include "gc/g1/heapRegionRemSet.hpp" 60 #include "gc/g1/heapRegionSet.inline.hpp" 61 #include "gc/g1/vm_operations_g1.hpp" 62 #include "gc/shared/gcHeapSummary.hpp" 63 #include "gc/shared/gcId.hpp" 64 #include "gc/shared/gcLocker.inline.hpp" 65 #include "gc/shared/gcTimer.hpp" 66 #include "gc/shared/gcTrace.hpp" 67 #include "gc/shared/gcTraceTime.inline.hpp" 68 #include "gc/shared/generationSpec.hpp" 69 #include "gc/shared/isGCActiveMark.hpp" 70 #include "gc/shared/preservedMarks.inline.hpp" 71 #include "gc/shared/suspendibleThreadSet.hpp" 72 #include "gc/shared/referenceProcessor.inline.hpp" 73 #include "gc/shared/taskqueue.inline.hpp" 74 #include "gc/shared/weakProcessor.hpp" 75 #include "logging/log.hpp" 76 #include "memory/allocation.hpp" 77 #include "memory/iterator.hpp" 78 #include "memory/resourceArea.hpp" 79 #include "oops/oop.inline.hpp" 80 #include "prims/resolvedMethodTable.hpp" 81 #include "runtime/atomic.hpp" 82 #include "runtime/init.hpp" 83 #include "runtime/orderAccess.inline.hpp" 84 #include "runtime/threadSMR.hpp" 85 #include "runtime/vmThread.hpp" 86 #include "utilities/align.hpp" 87 #include "utilities/globalDefinitions.hpp" 88 #include "utilities/stack.inline.hpp" 89 90 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0; 91 92 // INVARIANTS/NOTES 93 // 94 // All allocation activity covered by the G1CollectedHeap interface is 95 // serialized by acquiring the HeapLock. This happens in mem_allocate 96 // and allocate_new_tlab, which are the "entry" points to the 97 // allocation code from the rest of the JVM. (Note that this does not 98 // apply to TLAB allocation, which is not part of this interface: it 99 // is done by clients of this interface.) 100 101 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure { 102 private: 103 size_t _num_dirtied; 104 G1CollectedHeap* _g1h; 105 G1SATBCardTableLoggingModRefBS* _g1_bs; 106 107 HeapRegion* region_for_card(jbyte* card_ptr) const { 108 return _g1h->heap_region_containing(_g1_bs->addr_for(card_ptr)); 109 } 110 111 bool will_become_free(HeapRegion* hr) const { 112 // A region will be freed by free_collection_set if the region is in the 113 // collection set and has not had an evacuation failure. 114 return _g1h->is_in_cset(hr) && !hr->evacuation_failed(); 115 } 116 117 public: 118 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(), 119 _num_dirtied(0), _g1h(g1h), _g1_bs(g1h->g1_barrier_set()) { } 120 121 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 122 HeapRegion* hr = region_for_card(card_ptr); 123 124 // Should only dirty cards in regions that won't be freed. 125 if (!will_become_free(hr)) { 126 *card_ptr = CardTableModRefBS::dirty_card_val(); 127 _num_dirtied++; 128 } 129 130 return true; 131 } 132 133 size_t num_dirtied() const { return _num_dirtied; } 134 }; 135 136 137 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) { 138 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions); 139 } 140 141 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) { 142 // The from card cache is not the memory that is actually committed. So we cannot 143 // take advantage of the zero_filled parameter. 144 reset_from_card_cache(start_idx, num_regions); 145 } 146 147 148 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index, 149 MemRegion mr) { 150 return new HeapRegion(hrs_index, bot(), mr); 151 } 152 153 // Private methods. 154 155 HeapRegion* 156 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) { 157 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 158 while (!_secondary_free_list.is_empty() || free_regions_coming()) { 159 if (!_secondary_free_list.is_empty()) { 160 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : " 161 "secondary_free_list has %u entries", 162 _secondary_free_list.length()); 163 // It looks as if there are free regions available on the 164 // secondary_free_list. Let's move them to the free_list and try 165 // again to allocate from it. 166 append_secondary_free_list(); 167 168 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not " 169 "empty we should have moved at least one entry to the free_list"); 170 HeapRegion* res = _hrm.allocate_free_region(is_old); 171 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : " 172 "allocated " HR_FORMAT " from secondary_free_list", 173 HR_FORMAT_PARAMS(res)); 174 return res; 175 } 176 177 // Wait here until we get notified either when (a) there are no 178 // more free regions coming or (b) some regions have been moved on 179 // the secondary_free_list. 180 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 181 } 182 183 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : " 184 "could not allocate from secondary_free_list"); 185 return NULL; 186 } 187 188 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) { 189 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords, 190 "the only time we use this to allocate a humongous region is " 191 "when we are allocating a single humongous region"); 192 193 HeapRegion* res; 194 if (G1StressConcRegionFreeing) { 195 if (!_secondary_free_list.is_empty()) { 196 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : " 197 "forced to look at the secondary_free_list"); 198 res = new_region_try_secondary_free_list(is_old); 199 if (res != NULL) { 200 return res; 201 } 202 } 203 } 204 205 res = _hrm.allocate_free_region(is_old); 206 207 if (res == NULL) { 208 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : " 209 "res == NULL, trying the secondary_free_list"); 210 res = new_region_try_secondary_free_list(is_old); 211 } 212 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) { 213 // Currently, only attempts to allocate GC alloc regions set 214 // do_expand to true. So, we should only reach here during a 215 // safepoint. If this assumption changes we might have to 216 // reconsider the use of _expand_heap_after_alloc_failure. 217 assert(SafepointSynchronize::is_at_safepoint(), "invariant"); 218 219 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B", 220 word_size * HeapWordSize); 221 222 if (expand(word_size * HeapWordSize)) { 223 // Given that expand() succeeded in expanding the heap, and we 224 // always expand the heap by an amount aligned to the heap 225 // region size, the free list should in theory not be empty. 226 // In either case allocate_free_region() will check for NULL. 227 res = _hrm.allocate_free_region(is_old); 228 } else { 229 _expand_heap_after_alloc_failure = false; 230 } 231 } 232 return res; 233 } 234 235 HeapWord* 236 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first, 237 uint num_regions, 238 size_t word_size, 239 AllocationContext_t context) { 240 assert(first != G1_NO_HRM_INDEX, "pre-condition"); 241 assert(is_humongous(word_size), "word_size should be humongous"); 242 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition"); 243 244 // Index of last region in the series. 245 uint last = first + num_regions - 1; 246 247 // We need to initialize the region(s) we just discovered. This is 248 // a bit tricky given that it can happen concurrently with 249 // refinement threads refining cards on these regions and 250 // potentially wanting to refine the BOT as they are scanning 251 // those cards (this can happen shortly after a cleanup; see CR 252 // 6991377). So we have to set up the region(s) carefully and in 253 // a specific order. 254 255 // The word size sum of all the regions we will allocate. 256 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords; 257 assert(word_size <= word_size_sum, "sanity"); 258 259 // This will be the "starts humongous" region. 260 HeapRegion* first_hr = region_at(first); 261 // The header of the new object will be placed at the bottom of 262 // the first region. 263 HeapWord* new_obj = first_hr->bottom(); 264 // This will be the new top of the new object. 265 HeapWord* obj_top = new_obj + word_size; 266 267 // First, we need to zero the header of the space that we will be 268 // allocating. When we update top further down, some refinement 269 // threads might try to scan the region. By zeroing the header we 270 // ensure that any thread that will try to scan the region will 271 // come across the zero klass word and bail out. 272 // 273 // NOTE: It would not have been correct to have used 274 // CollectedHeap::fill_with_object() and make the space look like 275 // an int array. The thread that is doing the allocation will 276 // later update the object header to a potentially different array 277 // type and, for a very short period of time, the klass and length 278 // fields will be inconsistent. This could cause a refinement 279 // thread to calculate the object size incorrectly. 280 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0); 281 282 // Next, pad out the unused tail of the last region with filler 283 // objects, for improved usage accounting. 284 // How many words we use for filler objects. 285 size_t word_fill_size = word_size_sum - word_size; 286 287 // How many words memory we "waste" which cannot hold a filler object. 288 size_t words_not_fillable = 0; 289 290 if (word_fill_size >= min_fill_size()) { 291 fill_with_objects(obj_top, word_fill_size); 292 } else if (word_fill_size > 0) { 293 // We have space to fill, but we cannot fit an object there. 294 words_not_fillable = word_fill_size; 295 word_fill_size = 0; 296 } 297 298 // We will set up the first region as "starts humongous". This 299 // will also update the BOT covering all the regions to reflect 300 // that there is a single object that starts at the bottom of the 301 // first region. 302 first_hr->set_starts_humongous(obj_top, word_fill_size); 303 first_hr->set_allocation_context(context); 304 // Then, if there are any, we will set up the "continues 305 // humongous" regions. 306 HeapRegion* hr = NULL; 307 for (uint i = first + 1; i <= last; ++i) { 308 hr = region_at(i); 309 hr->set_continues_humongous(first_hr); 310 hr->set_allocation_context(context); 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, AllocationContext_t context) { 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, 430 word_size, context); 431 assert(result != NULL, "it should always return a valid result"); 432 433 // A successful humongous object allocation changes the used space 434 // information of the old generation so we need to recalculate the 435 // sizes and update the jstat counters here. 436 g1mm()->update_sizes(); 437 } 438 439 _verifier->verify_region_sets_optional(); 440 441 return result; 442 } 443 444 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) { 445 assert_heap_not_locked_and_not_at_safepoint(); 446 assert(!is_humongous(word_size), "we do not allow humongous TLABs"); 447 448 return attempt_allocation(word_size); 449 } 450 451 HeapWord* 452 G1CollectedHeap::mem_allocate(size_t word_size, 453 bool* gc_overhead_limit_was_exceeded) { 454 assert_heap_not_locked_and_not_at_safepoint(); 455 456 if (is_humongous(word_size)) { 457 return attempt_allocation_humongous(word_size); 458 } 459 return attempt_allocation(word_size); 460 } 461 462 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size, 463 AllocationContext_t context) { 464 ResourceMark rm; // For retrieving the thread names in log messages. 465 466 // Make sure you read the note in attempt_allocation_humongous(). 467 468 assert_heap_not_locked_and_not_at_safepoint(); 469 assert(!is_humongous(word_size), "attempt_allocation_slow() should not " 470 "be called for humongous allocation requests"); 471 472 // We should only get here after the first-level allocation attempt 473 // (attempt_allocation()) failed to allocate. 474 475 // We will loop until a) we manage to successfully perform the 476 // allocation or b) we successfully schedule a collection which 477 // fails to perform the allocation. b) is the only case when we'll 478 // return NULL. 479 HeapWord* result = NULL; 480 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 481 bool should_try_gc; 482 uint gc_count_before; 483 484 { 485 MutexLockerEx x(Heap_lock); 486 result = _allocator->attempt_allocation_locked(word_size, context); 487 if (result != NULL) { 488 return result; 489 } 490 491 // If the GCLocker is active and we are bound for a GC, try expanding young gen. 492 // This is different to when only GCLocker::needs_gc() is set: try to avoid 493 // waiting because the GCLocker is active to not wait too long. 494 if (GCLocker::is_active_and_needs_gc() && g1_policy()->can_expand_young_list()) { 495 // No need for an ergo message here, can_expand_young_list() does this when 496 // it returns true. 497 result = _allocator->attempt_allocation_force(word_size, context); 498 if (result != NULL) { 499 return result; 500 } 501 } 502 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until 503 // the GCLocker initiated GC has been performed and then retry. This includes 504 // the case when the GC Locker is not active but has not been performed. 505 should_try_gc = !GCLocker::needs_gc(); 506 // Read the GC count while still holding the Heap_lock. 507 gc_count_before = total_collections(); 508 } 509 510 if (should_try_gc) { 511 bool succeeded; 512 result = do_collection_pause(word_size, gc_count_before, &succeeded, 513 GCCause::_g1_inc_collection_pause); 514 if (result != NULL) { 515 assert(succeeded, "only way to get back a non-NULL result"); 516 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT, 517 Thread::current()->name(), p2i(result)); 518 return result; 519 } 520 521 if (succeeded) { 522 // We successfully scheduled a collection which failed to allocate. No 523 // point in trying to allocate further. We'll just return NULL. 524 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate " 525 SIZE_FORMAT " words", Thread::current()->name(), word_size); 526 return NULL; 527 } 528 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words", 529 Thread::current()->name(), word_size); 530 } else { 531 // Failed to schedule a collection. 532 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 533 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating " 534 SIZE_FORMAT " words", Thread::current()->name(), word_size); 535 return NULL; 536 } 537 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name()); 538 // The GCLocker is either active or the GCLocker initiated 539 // GC has not yet been performed. Stall until it is and 540 // then retry the allocation. 541 GCLocker::stall_until_clear(); 542 gclocker_retry_count += 1; 543 } 544 545 // We can reach here if we were unsuccessful in scheduling a 546 // collection (because another thread beat us to it) or if we were 547 // stalled due to the GC locker. In either can we should retry the 548 // allocation attempt in case another thread successfully 549 // performed a collection and reclaimed enough space. We do the 550 // first attempt (without holding the Heap_lock) here and the 551 // follow-on attempt will be at the start of the next loop 552 // iteration (after taking the Heap_lock). 553 554 result = _allocator->attempt_allocation(word_size, context); 555 if (result != NULL) { 556 return result; 557 } 558 559 // Give a warning if we seem to be looping forever. 560 if ((QueuedAllocationWarningCount > 0) && 561 (try_count % QueuedAllocationWarningCount == 0)) { 562 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words", 563 Thread::current()->name(), try_count, word_size); 564 } 565 } 566 567 ShouldNotReachHere(); 568 return NULL; 569 } 570 571 void G1CollectedHeap::begin_archive_alloc_range(bool open) { 572 assert_at_safepoint(true /* should_be_vm_thread */); 573 if (_archive_allocator == NULL) { 574 _archive_allocator = G1ArchiveAllocator::create_allocator(this, open); 575 } 576 } 577 578 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) { 579 // Allocations in archive regions cannot be of a size that would be considered 580 // humongous even for a minimum-sized region, because G1 region sizes/boundaries 581 // may be different at archive-restore time. 582 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words()); 583 } 584 585 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) { 586 assert_at_safepoint(true /* should_be_vm_thread */); 587 assert(_archive_allocator != NULL, "_archive_allocator not initialized"); 588 if (is_archive_alloc_too_large(word_size)) { 589 return NULL; 590 } 591 return _archive_allocator->archive_mem_allocate(word_size); 592 } 593 594 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges, 595 size_t end_alignment_in_bytes) { 596 assert_at_safepoint(true /* should_be_vm_thread */); 597 assert(_archive_allocator != NULL, "_archive_allocator not initialized"); 598 599 // Call complete_archive to do the real work, filling in the MemRegion 600 // array with the archive regions. 601 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes); 602 delete _archive_allocator; 603 _archive_allocator = NULL; 604 } 605 606 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) { 607 assert(ranges != NULL, "MemRegion array NULL"); 608 assert(count != 0, "No MemRegions provided"); 609 MemRegion reserved = _hrm.reserved(); 610 for (size_t i = 0; i < count; i++) { 611 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) { 612 return false; 613 } 614 } 615 return true; 616 } 617 618 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, 619 size_t count, 620 bool open) { 621 assert(!is_init_completed(), "Expect to be called at JVM init time"); 622 assert(ranges != NULL, "MemRegion array NULL"); 623 assert(count != 0, "No MemRegions provided"); 624 MutexLockerEx x(Heap_lock); 625 626 MemRegion reserved = _hrm.reserved(); 627 HeapWord* prev_last_addr = NULL; 628 HeapRegion* prev_last_region = NULL; 629 630 // Temporarily disable pretouching of heap pages. This interface is used 631 // when mmap'ing archived heap data in, so pre-touching is wasted. 632 FlagSetting fs(AlwaysPreTouch, false); 633 634 // Enable archive object checking used by G1MarkSweep. We have to let it know 635 // about each archive range, so that objects in those ranges aren't marked. 636 G1ArchiveAllocator::enable_archive_object_check(); 637 638 // For each specified MemRegion range, allocate the corresponding G1 639 // regions and mark them as archive regions. We expect the ranges 640 // in ascending starting address order, without overlap. 641 for (size_t i = 0; i < count; i++) { 642 MemRegion curr_range = ranges[i]; 643 HeapWord* start_address = curr_range.start(); 644 size_t word_size = curr_range.word_size(); 645 HeapWord* last_address = curr_range.last(); 646 size_t commits = 0; 647 648 guarantee(reserved.contains(start_address) && reserved.contains(last_address), 649 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 650 p2i(start_address), p2i(last_address)); 651 guarantee(start_address > prev_last_addr, 652 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 653 p2i(start_address), p2i(prev_last_addr)); 654 prev_last_addr = last_address; 655 656 // Check for ranges that start in the same G1 region in which the previous 657 // range ended, and adjust the start address so we don't try to allocate 658 // the same region again. If the current range is entirely within that 659 // region, skip it, just adjusting the recorded top. 660 HeapRegion* start_region = _hrm.addr_to_region(start_address); 661 if ((prev_last_region != NULL) && (start_region == prev_last_region)) { 662 start_address = start_region->end(); 663 if (start_address > last_address) { 664 increase_used(word_size * HeapWordSize); 665 start_region->set_top(last_address + 1); 666 continue; 667 } 668 start_region->set_top(start_address); 669 curr_range = MemRegion(start_address, last_address + 1); 670 start_region = _hrm.addr_to_region(start_address); 671 } 672 673 // Perform the actual region allocation, exiting if it fails. 674 // Then note how much new space we have allocated. 675 if (!_hrm.allocate_containing_regions(curr_range, &commits, workers())) { 676 return false; 677 } 678 increase_used(word_size * HeapWordSize); 679 if (commits != 0) { 680 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B", 681 HeapRegion::GrainWords * HeapWordSize * commits); 682 683 } 684 685 // Mark each G1 region touched by the range as archive, add it to 686 // the old set, and set the allocation context and top. 687 HeapRegion* curr_region = _hrm.addr_to_region(start_address); 688 HeapRegion* last_region = _hrm.addr_to_region(last_address); 689 prev_last_region = last_region; 690 691 while (curr_region != NULL) { 692 assert(curr_region->is_empty() && !curr_region->is_pinned(), 693 "Region already in use (index %u)", curr_region->hrm_index()); 694 curr_region->set_allocation_context(AllocationContext::system()); 695 if (open) { 696 curr_region->set_open_archive(); 697 } else { 698 curr_region->set_closed_archive(); 699 } 700 _hr_printer.alloc(curr_region); 701 _old_set.add(curr_region); 702 HeapWord* top; 703 HeapRegion* next_region; 704 if (curr_region != last_region) { 705 top = curr_region->end(); 706 next_region = _hrm.next_region_in_heap(curr_region); 707 } else { 708 top = last_address + 1; 709 next_region = NULL; 710 } 711 curr_region->set_top(top); 712 curr_region->set_first_dead(top); 713 curr_region->set_end_of_live(top); 714 curr_region = next_region; 715 } 716 717 // Notify mark-sweep of the archive 718 G1ArchiveAllocator::set_range_archive(curr_range, open); 719 } 720 return true; 721 } 722 723 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) { 724 assert(!is_init_completed(), "Expect to be called at JVM init time"); 725 assert(ranges != NULL, "MemRegion array NULL"); 726 assert(count != 0, "No MemRegions provided"); 727 MemRegion reserved = _hrm.reserved(); 728 HeapWord *prev_last_addr = NULL; 729 HeapRegion* prev_last_region = NULL; 730 731 // For each MemRegion, create filler objects, if needed, in the G1 regions 732 // that contain the address range. The address range actually within the 733 // MemRegion will not be modified. That is assumed to have been initialized 734 // elsewhere, probably via an mmap of archived heap data. 735 MutexLockerEx x(Heap_lock); 736 for (size_t i = 0; i < count; i++) { 737 HeapWord* start_address = ranges[i].start(); 738 HeapWord* last_address = ranges[i].last(); 739 740 assert(reserved.contains(start_address) && reserved.contains(last_address), 741 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 742 p2i(start_address), p2i(last_address)); 743 assert(start_address > prev_last_addr, 744 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 745 p2i(start_address), p2i(prev_last_addr)); 746 747 HeapRegion* start_region = _hrm.addr_to_region(start_address); 748 HeapRegion* last_region = _hrm.addr_to_region(last_address); 749 HeapWord* bottom_address = start_region->bottom(); 750 751 // Check for a range beginning in the same region in which the 752 // previous one ended. 753 if (start_region == prev_last_region) { 754 bottom_address = prev_last_addr + 1; 755 } 756 757 // Verify that the regions were all marked as archive regions by 758 // alloc_archive_regions. 759 HeapRegion* curr_region = start_region; 760 while (curr_region != NULL) { 761 guarantee(curr_region->is_archive(), 762 "Expected archive region at index %u", curr_region->hrm_index()); 763 if (curr_region != last_region) { 764 curr_region = _hrm.next_region_in_heap(curr_region); 765 } else { 766 curr_region = NULL; 767 } 768 } 769 770 prev_last_addr = last_address; 771 prev_last_region = last_region; 772 773 // Fill the memory below the allocated range with dummy object(s), 774 // if the region bottom does not match the range start, or if the previous 775 // range ended within the same G1 region, and there is a gap. 776 if (start_address != bottom_address) { 777 size_t fill_size = pointer_delta(start_address, bottom_address); 778 G1CollectedHeap::fill_with_objects(bottom_address, fill_size); 779 increase_used(fill_size * HeapWordSize); 780 } 781 } 782 } 783 784 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size) { 785 assert_heap_not_locked_and_not_at_safepoint(); 786 assert(!is_humongous(word_size), "attempt_allocation() should not " 787 "be called for humongous allocation requests"); 788 789 AllocationContext_t context = AllocationContext::current(); 790 HeapWord* result = _allocator->attempt_allocation(word_size, context); 791 792 if (result == NULL) { 793 result = attempt_allocation_slow(word_size, context); 794 } 795 assert_heap_not_locked(); 796 if (result != NULL) { 797 dirty_young_block(result, word_size); 798 } 799 return result; 800 } 801 802 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) { 803 assert(!is_init_completed(), "Expect to be called at JVM init time"); 804 assert(ranges != NULL, "MemRegion array NULL"); 805 assert(count != 0, "No MemRegions provided"); 806 MemRegion reserved = _hrm.reserved(); 807 HeapWord* prev_last_addr = NULL; 808 HeapRegion* prev_last_region = NULL; 809 size_t size_used = 0; 810 size_t uncommitted_regions = 0; 811 812 // For each Memregion, free the G1 regions that constitute it, and 813 // notify mark-sweep that the range is no longer to be considered 'archive.' 814 MutexLockerEx x(Heap_lock); 815 for (size_t i = 0; i < count; i++) { 816 HeapWord* start_address = ranges[i].start(); 817 HeapWord* last_address = ranges[i].last(); 818 819 assert(reserved.contains(start_address) && reserved.contains(last_address), 820 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 821 p2i(start_address), p2i(last_address)); 822 assert(start_address > prev_last_addr, 823 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 824 p2i(start_address), p2i(prev_last_addr)); 825 size_used += ranges[i].byte_size(); 826 prev_last_addr = last_address; 827 828 HeapRegion* start_region = _hrm.addr_to_region(start_address); 829 HeapRegion* last_region = _hrm.addr_to_region(last_address); 830 831 // Check for ranges that start in the same G1 region in which the previous 832 // range ended, and adjust the start address so we don't try to free 833 // the same region again. If the current range is entirely within that 834 // region, skip it. 835 if (start_region == prev_last_region) { 836 start_address = start_region->end(); 837 if (start_address > last_address) { 838 continue; 839 } 840 start_region = _hrm.addr_to_region(start_address); 841 } 842 prev_last_region = last_region; 843 844 // After verifying that each region was marked as an archive region by 845 // alloc_archive_regions, set it free and empty and uncommit it. 846 HeapRegion* curr_region = start_region; 847 while (curr_region != NULL) { 848 guarantee(curr_region->is_archive(), 849 "Expected archive region at index %u", curr_region->hrm_index()); 850 uint curr_index = curr_region->hrm_index(); 851 _old_set.remove(curr_region); 852 curr_region->set_free(); 853 curr_region->set_top(curr_region->bottom()); 854 if (curr_region != last_region) { 855 curr_region = _hrm.next_region_in_heap(curr_region); 856 } else { 857 curr_region = NULL; 858 } 859 _hrm.shrink_at(curr_index, 1); 860 uncommitted_regions++; 861 } 862 863 // Notify mark-sweep that this is no longer an archive range. 864 G1ArchiveAllocator::set_range_archive(ranges[i], false); 865 } 866 867 if (uncommitted_regions != 0) { 868 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B", 869 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions); 870 } 871 decrease_used(size_used); 872 } 873 874 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) { 875 ResourceMark rm; // For retrieving the thread names in log messages. 876 877 // The structure of this method has a lot of similarities to 878 // attempt_allocation_slow(). The reason these two were not merged 879 // into a single one is that such a method would require several "if 880 // allocation is not humongous do this, otherwise do that" 881 // conditional paths which would obscure its flow. In fact, an early 882 // version of this code did use a unified method which was harder to 883 // follow and, as a result, it had subtle bugs that were hard to 884 // track down. So keeping these two methods separate allows each to 885 // be more readable. It will be good to keep these two in sync as 886 // much as possible. 887 888 assert_heap_not_locked_and_not_at_safepoint(); 889 assert(is_humongous(word_size), "attempt_allocation_humongous() " 890 "should only be called for humongous allocations"); 891 892 // Humongous objects can exhaust the heap quickly, so we should check if we 893 // need to start a marking cycle at each humongous object allocation. We do 894 // the check before we do the actual allocation. The reason for doing it 895 // before the allocation is that we avoid having to keep track of the newly 896 // allocated memory while we do a GC. 897 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation", 898 word_size)) { 899 collect(GCCause::_g1_humongous_allocation); 900 } 901 902 // We will loop until a) we manage to successfully perform the 903 // allocation or b) we successfully schedule a collection which 904 // fails to perform the allocation. b) is the only case when we'll 905 // return NULL. 906 HeapWord* result = NULL; 907 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 908 bool should_try_gc; 909 uint gc_count_before; 910 911 912 { 913 MutexLockerEx x(Heap_lock); 914 915 // Given that humongous objects are not allocated in young 916 // regions, we'll first try to do the allocation without doing a 917 // collection hoping that there's enough space in the heap. 918 result = humongous_obj_allocate(word_size, AllocationContext::current()); 919 if (result != NULL) { 920 size_t size_in_regions = humongous_obj_size_in_regions(word_size); 921 g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes); 922 return result; 923 } 924 925 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until 926 // the GCLocker initiated GC has been performed and then retry. This includes 927 // the case when the GC Locker is not active but has not been performed. 928 should_try_gc = !GCLocker::needs_gc(); 929 // Read the GC count while still holding the Heap_lock. 930 gc_count_before = total_collections(); 931 } 932 933 if (should_try_gc) { 934 bool succeeded; 935 result = do_collection_pause(word_size, gc_count_before, &succeeded, 936 GCCause::_g1_humongous_allocation); 937 if (result != NULL) { 938 assert(succeeded, "only way to get back a non-NULL result"); 939 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT, 940 Thread::current()->name(), p2i(result)); 941 return result; 942 } 943 944 if (succeeded) { 945 // We successfully scheduled a collection which failed to allocate. No 946 // point in trying to allocate further. We'll just return NULL. 947 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate " 948 SIZE_FORMAT " words", Thread::current()->name(), word_size); 949 return NULL; 950 } 951 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "", 952 Thread::current()->name(), word_size); 953 } else { 954 // Failed to schedule a collection. 955 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 956 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating " 957 SIZE_FORMAT " words", Thread::current()->name(), word_size); 958 return NULL; 959 } 960 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name()); 961 // The GCLocker is either active or the GCLocker initiated 962 // GC has not yet been performed. Stall until it is and 963 // then retry the allocation. 964 GCLocker::stall_until_clear(); 965 gclocker_retry_count += 1; 966 } 967 968 969 // We can reach here if we were unsuccessful in scheduling a 970 // collection (because another thread beat us to it) or if we were 971 // stalled due to the GC locker. In either can we should retry the 972 // allocation attempt in case another thread successfully 973 // performed a collection and reclaimed enough space. 974 // Humongous object allocation always needs a lock, so we wait for the retry 975 // in the next iteration of the loop, unlike for the regular iteration case. 976 // Give a warning if we seem to be looping forever. 977 978 if ((QueuedAllocationWarningCount > 0) && 979 (try_count % QueuedAllocationWarningCount == 0)) { 980 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words", 981 Thread::current()->name(), try_count, word_size); 982 } 983 } 984 985 ShouldNotReachHere(); 986 return NULL; 987 } 988 989 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size, 990 AllocationContext_t context, 991 bool expect_null_mutator_alloc_region) { 992 assert_at_safepoint(true /* should_be_vm_thread */); 993 assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region, 994 "the current alloc region was unexpectedly found to be non-NULL"); 995 996 if (!is_humongous(word_size)) { 997 return _allocator->attempt_allocation_locked(word_size, context); 998 } else { 999 HeapWord* result = humongous_obj_allocate(word_size, context); 1000 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) { 1001 collector_state()->set_initiate_conc_mark_if_possible(true); 1002 } 1003 return result; 1004 } 1005 1006 ShouldNotReachHere(); 1007 } 1008 1009 class PostCompactionPrinterClosure: public HeapRegionClosure { 1010 private: 1011 G1HRPrinter* _hr_printer; 1012 public: 1013 bool do_heap_region(HeapRegion* hr) { 1014 assert(!hr->is_young(), "not expecting to find young regions"); 1015 _hr_printer->post_compaction(hr); 1016 return false; 1017 } 1018 1019 PostCompactionPrinterClosure(G1HRPrinter* hr_printer) 1020 : _hr_printer(hr_printer) { } 1021 }; 1022 1023 void G1CollectedHeap::print_hrm_post_compaction() { 1024 if (_hr_printer.is_active()) { 1025 PostCompactionPrinterClosure cl(hr_printer()); 1026 heap_region_iterate(&cl); 1027 } 1028 } 1029 1030 void G1CollectedHeap::abort_concurrent_cycle() { 1031 // Note: When we have a more flexible GC logging framework that 1032 // allows us to add optional attributes to a GC log record we 1033 // could consider timing and reporting how long we wait in the 1034 // following two methods. 1035 wait_while_free_regions_coming(); 1036 // If we start the compaction before the CM threads finish 1037 // scanning the root regions we might trip them over as we'll 1038 // be moving objects / updating references. So let's wait until 1039 // they are done. By telling them to abort, they should complete 1040 // early. 1041 _cm->root_regions()->abort(); 1042 _cm->root_regions()->wait_until_scan_finished(); 1043 append_secondary_free_list_if_not_empty_with_lock(); 1044 1045 // Disable discovery and empty the discovered lists 1046 // for the CM ref processor. 1047 ref_processor_cm()->disable_discovery(); 1048 ref_processor_cm()->abandon_partial_discovery(); 1049 ref_processor_cm()->verify_no_references_recorded(); 1050 1051 // Abandon current iterations of concurrent marking and concurrent 1052 // refinement, if any are in progress. 1053 concurrent_mark()->abort(); 1054 } 1055 1056 void G1CollectedHeap::prepare_heap_for_full_collection() { 1057 // Make sure we'll choose a new allocation region afterwards. 1058 _allocator->release_mutator_alloc_region(); 1059 _allocator->abandon_gc_alloc_regions(); 1060 g1_rem_set()->cleanupHRRS(); 1061 1062 // We may have added regions to the current incremental collection 1063 // set between the last GC or pause and now. We need to clear the 1064 // incremental collection set and then start rebuilding it afresh 1065 // after this full GC. 1066 abandon_collection_set(collection_set()); 1067 1068 tear_down_region_sets(false /* free_list_only */); 1069 collector_state()->set_gcs_are_young(true); 1070 } 1071 1072 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) { 1073 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant"); 1074 assert(used() == recalculate_used(), "Should be equal"); 1075 _verifier->verify_region_sets_optional(); 1076 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull); 1077 _verifier->check_bitmaps("Full GC Start"); 1078 } 1079 1080 void G1CollectedHeap::prepare_heap_for_mutators() { 1081 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 1082 ClassLoaderDataGraph::purge(); 1083 MetaspaceAux::verify_metrics(); 1084 1085 // Prepare heap for normal collections. 1086 assert(num_free_regions() == 0, "we should not have added any free regions"); 1087 rebuild_region_sets(false /* free_list_only */); 1088 abort_refinement(); 1089 resize_if_necessary_after_full_collection(); 1090 1091 // Rebuild the strong code root lists for each region 1092 rebuild_strong_code_roots(); 1093 1094 // Start a new incremental collection set for the next pause 1095 start_new_collection_set(); 1096 1097 _allocator->init_mutator_alloc_region(); 1098 1099 // Post collection state updates. 1100 MetaspaceGC::compute_new_size(); 1101 } 1102 1103 void G1CollectedHeap::abort_refinement() { 1104 if (_hot_card_cache->use_cache()) { 1105 _hot_card_cache->reset_hot_cache(); 1106 } 1107 1108 // Discard all remembered set updates. 1109 JavaThread::dirty_card_queue_set().abandon_logs(); 1110 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty"); 1111 } 1112 1113 void G1CollectedHeap::verify_after_full_collection() { 1114 check_gc_time_stamps(); 1115 _hrm.verify_optional(); 1116 _verifier->verify_region_sets_optional(); 1117 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull); 1118 // Clear the previous marking bitmap, if needed for bitmap verification. 1119 // Note we cannot do this when we clear the next marking bitmap in 1120 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the 1121 // objects marked during a full GC against the previous bitmap. 1122 // But we need to clear it before calling check_bitmaps below since 1123 // the full GC has compacted objects and updated TAMS but not updated 1124 // the prev bitmap. 1125 if (G1VerifyBitmaps) { 1126 GCTraceTime(Debug, gc)("Clear Bitmap for Verification"); 1127 _cm->clear_prev_bitmap(workers()); 1128 } 1129 _verifier->check_bitmaps("Full GC End"); 1130 1131 // At this point there should be no regions in the 1132 // entire heap tagged as young. 1133 assert(check_young_list_empty(), "young list should be empty at this point"); 1134 1135 // Note: since we've just done a full GC, concurrent 1136 // marking is no longer active. Therefore we need not 1137 // re-enable reference discovery for the CM ref processor. 1138 // That will be done at the start of the next marking cycle. 1139 // We also know that the STW processor should no longer 1140 // discover any new references. 1141 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 1142 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition"); 1143 ref_processor_stw()->verify_no_references_recorded(); 1144 ref_processor_cm()->verify_no_references_recorded(); 1145 } 1146 1147 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) { 1148 // Post collection logging. 1149 // We should do this after we potentially resize the heap so 1150 // that all the COMMIT / UNCOMMIT events are generated before 1151 // the compaction events. 1152 print_hrm_post_compaction(); 1153 heap_transition->print(); 1154 print_heap_after_gc(); 1155 print_heap_regions(); 1156 #ifdef TRACESPINNING 1157 ParallelTaskTerminator::print_termination_counts(); 1158 #endif 1159 } 1160 1161 bool G1CollectedHeap::do_full_collection(bool explicit_gc, 1162 bool clear_all_soft_refs) { 1163 assert_at_safepoint(true /* should_be_vm_thread */); 1164 1165 if (GCLocker::check_active_before_gc()) { 1166 // Full GC was not completed. 1167 return false; 1168 } 1169 1170 const bool do_clear_all_soft_refs = clear_all_soft_refs || 1171 collector_policy()->should_clear_all_soft_refs(); 1172 1173 G1FullCollector collector(this, &_full_gc_memory_manager, explicit_gc, do_clear_all_soft_refs); 1174 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true); 1175 1176 collector.prepare_collection(); 1177 collector.collect(); 1178 collector.complete_collection(); 1179 1180 // Full collection was successfully completed. 1181 return true; 1182 } 1183 1184 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) { 1185 // Currently, there is no facility in the do_full_collection(bool) API to notify 1186 // the caller that the collection did not succeed (e.g., because it was locked 1187 // out by the GC locker). So, right now, we'll ignore the return value. 1188 bool dummy = do_full_collection(true, /* explicit_gc */ 1189 clear_all_soft_refs); 1190 } 1191 1192 void G1CollectedHeap::resize_if_necessary_after_full_collection() { 1193 // Capacity, free and used after the GC counted as full regions to 1194 // include the waste in the following calculations. 1195 const size_t capacity_after_gc = capacity(); 1196 const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes(); 1197 1198 // This is enforced in arguments.cpp. 1199 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, 1200 "otherwise the code below doesn't make sense"); 1201 1202 // We don't have floating point command-line arguments 1203 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0; 1204 const double maximum_used_percentage = 1.0 - minimum_free_percentage; 1205 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0; 1206 const double minimum_used_percentage = 1.0 - maximum_free_percentage; 1207 1208 const size_t min_heap_size = collector_policy()->min_heap_byte_size(); 1209 const size_t max_heap_size = collector_policy()->max_heap_byte_size(); 1210 1211 // We have to be careful here as these two calculations can overflow 1212 // 32-bit size_t's. 1213 double used_after_gc_d = (double) used_after_gc; 1214 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage; 1215 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage; 1216 1217 // Let's make sure that they are both under the max heap size, which 1218 // by default will make them fit into a size_t. 1219 double desired_capacity_upper_bound = (double) max_heap_size; 1220 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d, 1221 desired_capacity_upper_bound); 1222 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d, 1223 desired_capacity_upper_bound); 1224 1225 // We can now safely turn them into size_t's. 1226 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d; 1227 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d; 1228 1229 // This assert only makes sense here, before we adjust them 1230 // with respect to the min and max heap size. 1231 assert(minimum_desired_capacity <= maximum_desired_capacity, 1232 "minimum_desired_capacity = " SIZE_FORMAT ", " 1233 "maximum_desired_capacity = " SIZE_FORMAT, 1234 minimum_desired_capacity, maximum_desired_capacity); 1235 1236 // Should not be greater than the heap max size. No need to adjust 1237 // it with respect to the heap min size as it's a lower bound (i.e., 1238 // we'll try to make the capacity larger than it, not smaller). 1239 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size); 1240 // Should not be less than the heap min size. No need to adjust it 1241 // with respect to the heap max size as it's an upper bound (i.e., 1242 // we'll try to make the capacity smaller than it, not greater). 1243 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size); 1244 1245 if (capacity_after_gc < minimum_desired_capacity) { 1246 // Don't expand unless it's significant 1247 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc; 1248 1249 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). " 1250 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B " 1251 "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)", 1252 capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio); 1253 1254 expand(expand_bytes, _workers); 1255 1256 // No expansion, now see if we want to shrink 1257 } else if (capacity_after_gc > maximum_desired_capacity) { 1258 // Capacity too large, compute shrinking size 1259 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity; 1260 1261 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). " 1262 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B " 1263 "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)", 1264 capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio); 1265 1266 shrink(shrink_bytes); 1267 } 1268 } 1269 1270 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size, 1271 AllocationContext_t context, 1272 bool do_gc, 1273 bool clear_all_soft_refs, 1274 bool expect_null_mutator_alloc_region, 1275 bool* gc_succeeded) { 1276 *gc_succeeded = true; 1277 // Let's attempt the allocation first. 1278 HeapWord* result = 1279 attempt_allocation_at_safepoint(word_size, 1280 context, 1281 expect_null_mutator_alloc_region); 1282 if (result != NULL) { 1283 return result; 1284 } 1285 1286 // In a G1 heap, we're supposed to keep allocation from failing by 1287 // incremental pauses. Therefore, at least for now, we'll favor 1288 // expansion over collection. (This might change in the future if we can 1289 // do something smarter than full collection to satisfy a failed alloc.) 1290 result = expand_and_allocate(word_size, context); 1291 if (result != NULL) { 1292 return result; 1293 } 1294 1295 if (do_gc) { 1296 // Expansion didn't work, we'll try to do a Full GC. 1297 *gc_succeeded = do_full_collection(false, /* explicit_gc */ 1298 clear_all_soft_refs); 1299 } 1300 1301 return NULL; 1302 } 1303 1304 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size, 1305 AllocationContext_t context, 1306 bool* succeeded) { 1307 assert_at_safepoint(true /* should_be_vm_thread */); 1308 1309 // Attempts to allocate followed by Full GC. 1310 HeapWord* result = 1311 satisfy_failed_allocation_helper(word_size, 1312 context, 1313 true, /* do_gc */ 1314 false, /* clear_all_soft_refs */ 1315 false, /* expect_null_mutator_alloc_region */ 1316 succeeded); 1317 1318 if (result != NULL || !*succeeded) { 1319 return result; 1320 } 1321 1322 // Attempts to allocate followed by Full GC that will collect all soft references. 1323 result = satisfy_failed_allocation_helper(word_size, 1324 context, 1325 true, /* do_gc */ 1326 true, /* clear_all_soft_refs */ 1327 true, /* expect_null_mutator_alloc_region */ 1328 succeeded); 1329 1330 if (result != NULL || !*succeeded) { 1331 return result; 1332 } 1333 1334 // Attempts to allocate, no GC 1335 result = satisfy_failed_allocation_helper(word_size, 1336 context, 1337 false, /* do_gc */ 1338 false, /* clear_all_soft_refs */ 1339 true, /* expect_null_mutator_alloc_region */ 1340 succeeded); 1341 1342 if (result != NULL) { 1343 return result; 1344 } 1345 1346 assert(!collector_policy()->should_clear_all_soft_refs(), 1347 "Flag should have been handled and cleared prior to this point"); 1348 1349 // What else? We might try synchronous finalization later. If the total 1350 // space available is large enough for the allocation, then a more 1351 // complete compaction phase than we've tried so far might be 1352 // appropriate. 1353 return NULL; 1354 } 1355 1356 // Attempting to expand the heap sufficiently 1357 // to support an allocation of the given "word_size". If 1358 // successful, perform the allocation and return the address of the 1359 // allocated block, or else "NULL". 1360 1361 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) { 1362 assert_at_safepoint(true /* should_be_vm_thread */); 1363 1364 _verifier->verify_region_sets_optional(); 1365 1366 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes); 1367 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B", 1368 word_size * HeapWordSize); 1369 1370 1371 if (expand(expand_bytes, _workers)) { 1372 _hrm.verify_optional(); 1373 _verifier->verify_region_sets_optional(); 1374 return attempt_allocation_at_safepoint(word_size, 1375 context, 1376 false /* expect_null_mutator_alloc_region */); 1377 } 1378 return NULL; 1379 } 1380 1381 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) { 1382 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); 1383 aligned_expand_bytes = align_up(aligned_expand_bytes, 1384 HeapRegion::GrainBytes); 1385 1386 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B", 1387 expand_bytes, aligned_expand_bytes); 1388 1389 if (is_maximal_no_gc()) { 1390 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)"); 1391 return false; 1392 } 1393 1394 double expand_heap_start_time_sec = os::elapsedTime(); 1395 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes); 1396 assert(regions_to_expand > 0, "Must expand by at least one region"); 1397 1398 uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers); 1399 if (expand_time_ms != NULL) { 1400 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS; 1401 } 1402 1403 if (expanded_by > 0) { 1404 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes; 1405 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition"); 1406 g1_policy()->record_new_heap_size(num_regions()); 1407 } else { 1408 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)"); 1409 1410 // The expansion of the virtual storage space was unsuccessful. 1411 // Let's see if it was because we ran out of swap. 1412 if (G1ExitOnExpansionFailure && 1413 _hrm.available() >= regions_to_expand) { 1414 // We had head room... 1415 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion"); 1416 } 1417 } 1418 return regions_to_expand > 0; 1419 } 1420 1421 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) { 1422 size_t aligned_shrink_bytes = 1423 ReservedSpace::page_align_size_down(shrink_bytes); 1424 aligned_shrink_bytes = align_down(aligned_shrink_bytes, 1425 HeapRegion::GrainBytes); 1426 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes); 1427 1428 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove); 1429 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes; 1430 1431 1432 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", 1433 shrink_bytes, aligned_shrink_bytes, shrunk_bytes); 1434 if (num_regions_removed > 0) { 1435 g1_policy()->record_new_heap_size(num_regions()); 1436 } else { 1437 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)"); 1438 } 1439 } 1440 1441 void G1CollectedHeap::shrink(size_t shrink_bytes) { 1442 _verifier->verify_region_sets_optional(); 1443 1444 // We should only reach here at the end of a Full GC which means we 1445 // should not not be holding to any GC alloc regions. The method 1446 // below will make sure of that and do any remaining clean up. 1447 _allocator->abandon_gc_alloc_regions(); 1448 1449 // Instead of tearing down / rebuilding the free lists here, we 1450 // could instead use the remove_all_pending() method on free_list to 1451 // remove only the ones that we need to remove. 1452 tear_down_region_sets(true /* free_list_only */); 1453 shrink_helper(shrink_bytes); 1454 rebuild_region_sets(true /* free_list_only */); 1455 1456 _hrm.verify_optional(); 1457 _verifier->verify_region_sets_optional(); 1458 } 1459 1460 // Public methods. 1461 1462 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) : 1463 CollectedHeap(), 1464 _young_gen_sampling_thread(NULL), 1465 _collector_policy(collector_policy), 1466 _memory_manager("G1 Young Generation", "end of minor GC"), 1467 _full_gc_memory_manager("G1 Old Generation", "end of major GC"), 1468 _eden_pool(NULL), 1469 _survivor_pool(NULL), 1470 _old_pool(NULL), 1471 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()), 1472 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()), 1473 _g1_policy(create_g1_policy(_gc_timer_stw)), 1474 _collection_set(this, _g1_policy), 1475 _dirty_card_queue_set(false), 1476 _is_alive_closure_cm(this), 1477 _is_alive_closure_stw(this), 1478 _ref_processor_cm(NULL), 1479 _ref_processor_stw(NULL), 1480 _bot(NULL), 1481 _hot_card_cache(NULL), 1482 _g1_rem_set(NULL), 1483 _cr(NULL), 1484 _g1mm(NULL), 1485 _preserved_marks_set(true /* in_c_heap */), 1486 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()), 1487 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()), 1488 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()), 1489 _humongous_reclaim_candidates(), 1490 _has_humongous_reclaim_candidates(false), 1491 _archive_allocator(NULL), 1492 _free_regions_coming(false), 1493 _gc_time_stamp(0), 1494 _summary_bytes_used(0), 1495 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight), 1496 _old_evac_stats("Old", OldPLABSize, PLABWeight), 1497 _expand_heap_after_alloc_failure(true), 1498 _old_marking_cycles_started(0), 1499 _old_marking_cycles_completed(0), 1500 _in_cset_fast_test() { 1501 1502 _workers = new WorkGang("GC Thread", ParallelGCThreads, 1503 /* are_GC_task_threads */true, 1504 /* are_ConcurrentGC_threads */false); 1505 _workers->initialize_workers(); 1506 _verifier = new G1HeapVerifier(this); 1507 1508 _allocator = G1Allocator::create_allocator(this); 1509 1510 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics()); 1511 1512 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords); 1513 1514 // Override the default _filler_array_max_size so that no humongous filler 1515 // objects are created. 1516 _filler_array_max_size = _humongous_object_threshold_in_words; 1517 1518 uint n_queues = ParallelGCThreads; 1519 _task_queues = new RefToScanQueueSet(n_queues); 1520 1521 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC); 1522 1523 for (uint i = 0; i < n_queues; i++) { 1524 RefToScanQueue* q = new RefToScanQueue(); 1525 q->initialize(); 1526 _task_queues->register_queue(i, q); 1527 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo(); 1528 } 1529 1530 // Initialize the G1EvacuationFailureALot counters and flags. 1531 NOT_PRODUCT(reset_evacuation_should_fail();) 1532 1533 guarantee(_task_queues != NULL, "task_queues allocation failure."); 1534 } 1535 1536 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description, 1537 size_t size, 1538 size_t translation_factor) { 1539 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1); 1540 // Allocate a new reserved space, preferring to use large pages. 1541 ReservedSpace rs(size, preferred_page_size); 1542 G1RegionToSpaceMapper* result = 1543 G1RegionToSpaceMapper::create_mapper(rs, 1544 size, 1545 rs.alignment(), 1546 HeapRegion::GrainBytes, 1547 translation_factor, 1548 mtGC); 1549 1550 os::trace_page_sizes_for_requested_size(description, 1551 size, 1552 preferred_page_size, 1553 rs.alignment(), 1554 rs.base(), 1555 rs.size()); 1556 1557 return result; 1558 } 1559 1560 jint G1CollectedHeap::initialize_concurrent_refinement() { 1561 jint ecode = JNI_OK; 1562 _cr = G1ConcurrentRefine::create(&ecode); 1563 return ecode; 1564 } 1565 1566 jint G1CollectedHeap::initialize_young_gen_sampling_thread() { 1567 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread(); 1568 if (_young_gen_sampling_thread->osthread() == NULL) { 1569 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread"); 1570 return JNI_ENOMEM; 1571 } 1572 return JNI_OK; 1573 } 1574 1575 jint G1CollectedHeap::initialize() { 1576 os::enable_vtime(); 1577 1578 // Necessary to satisfy locking discipline assertions. 1579 1580 MutexLocker x(Heap_lock); 1581 1582 // While there are no constraints in the GC code that HeapWordSize 1583 // be any particular value, there are multiple other areas in the 1584 // system which believe this to be true (e.g. oop->object_size in some 1585 // cases incorrectly returns the size in wordSize units rather than 1586 // HeapWordSize). 1587 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 1588 1589 size_t init_byte_size = collector_policy()->initial_heap_byte_size(); 1590 size_t max_byte_size = collector_policy()->max_heap_byte_size(); 1591 size_t heap_alignment = collector_policy()->heap_alignment(); 1592 1593 // Ensure that the sizes are properly aligned. 1594 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1595 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1596 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap"); 1597 1598 // Reserve the maximum. 1599 1600 // When compressed oops are enabled, the preferred heap base 1601 // is calculated by subtracting the requested size from the 1602 // 32Gb boundary and using the result as the base address for 1603 // heap reservation. If the requested size is not aligned to 1604 // HeapRegion::GrainBytes (i.e. the alignment that is passed 1605 // into the ReservedHeapSpace constructor) then the actual 1606 // base of the reserved heap may end up differing from the 1607 // address that was requested (i.e. the preferred heap base). 1608 // If this happens then we could end up using a non-optimal 1609 // compressed oops mode. 1610 1611 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size, 1612 heap_alignment); 1613 1614 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size())); 1615 1616 // Create the barrier set for the entire reserved region. 1617 G1SATBCardTableLoggingModRefBS* bs 1618 = new G1SATBCardTableLoggingModRefBS(reserved_region()); 1619 bs->initialize(); 1620 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity"); 1621 set_barrier_set(bs); 1622 1623 // Create the hot card cache. 1624 _hot_card_cache = new G1HotCardCache(this); 1625 1626 // Carve out the G1 part of the heap. 1627 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size); 1628 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size(); 1629 G1RegionToSpaceMapper* heap_storage = 1630 G1RegionToSpaceMapper::create_mapper(g1_rs, 1631 g1_rs.size(), 1632 page_size, 1633 HeapRegion::GrainBytes, 1634 1, 1635 mtJavaHeap); 1636 os::trace_page_sizes("Heap", 1637 collector_policy()->min_heap_byte_size(), 1638 max_byte_size, 1639 page_size, 1640 heap_rs.base(), 1641 heap_rs.size()); 1642 heap_storage->set_mapping_changed_listener(&_listener); 1643 1644 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps. 1645 G1RegionToSpaceMapper* bot_storage = 1646 create_aux_memory_mapper("Block Offset Table", 1647 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize), 1648 G1BlockOffsetTable::heap_map_factor()); 1649 1650 G1RegionToSpaceMapper* cardtable_storage = 1651 create_aux_memory_mapper("Card Table", 1652 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize), 1653 G1SATBCardTableLoggingModRefBS::heap_map_factor()); 1654 1655 G1RegionToSpaceMapper* card_counts_storage = 1656 create_aux_memory_mapper("Card Counts Table", 1657 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize), 1658 G1CardCounts::heap_map_factor()); 1659 1660 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size()); 1661 G1RegionToSpaceMapper* prev_bitmap_storage = 1662 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1663 G1RegionToSpaceMapper* next_bitmap_storage = 1664 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1665 1666 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage); 1667 g1_barrier_set()->initialize(cardtable_storage); 1668 // Do later initialization work for concurrent refinement. 1669 _hot_card_cache->initialize(card_counts_storage); 1670 1671 // 6843694 - ensure that the maximum region index can fit 1672 // in the remembered set structures. 1673 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; 1674 guarantee((max_regions() - 1) <= max_region_idx, "too many regions"); 1675 1676 // Also create a G1 rem set. 1677 _g1_rem_set = new G1RemSet(this, g1_barrier_set(), _hot_card_cache); 1678 _g1_rem_set->initialize(max_capacity(), max_regions()); 1679 1680 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; 1681 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); 1682 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region, 1683 "too many cards per region"); 1684 1685 FreeRegionList::set_unrealistically_long_length(max_regions() + 1); 1686 1687 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage); 1688 1689 { 1690 HeapWord* start = _hrm.reserved().start(); 1691 HeapWord* end = _hrm.reserved().end(); 1692 size_t granularity = HeapRegion::GrainBytes; 1693 1694 _in_cset_fast_test.initialize(start, end, granularity); 1695 _humongous_reclaim_candidates.initialize(start, end, granularity); 1696 } 1697 1698 // Create the G1ConcurrentMark data structure and thread. 1699 // (Must do this late, so that "max_regions" is defined.) 1700 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage); 1701 if (_cm == NULL || !_cm->completed_initialization()) { 1702 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark"); 1703 return JNI_ENOMEM; 1704 } 1705 _cmThread = _cm->cm_thread(); 1706 1707 // Now expand into the initial heap size. 1708 if (!expand(init_byte_size, _workers)) { 1709 vm_shutdown_during_initialization("Failed to allocate initial heap."); 1710 return JNI_ENOMEM; 1711 } 1712 1713 // Perform any initialization actions delegated to the policy. 1714 g1_policy()->init(this, &_collection_set); 1715 1716 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon, 1717 SATB_Q_FL_lock, 1718 G1SATBProcessCompletedThreshold, 1719 Shared_SATB_Q_lock); 1720 1721 jint ecode = initialize_concurrent_refinement(); 1722 if (ecode != JNI_OK) { 1723 return ecode; 1724 } 1725 1726 ecode = initialize_young_gen_sampling_thread(); 1727 if (ecode != JNI_OK) { 1728 return ecode; 1729 } 1730 1731 JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon, 1732 DirtyCardQ_FL_lock, 1733 (int)concurrent_refine()->yellow_zone(), 1734 (int)concurrent_refine()->red_zone(), 1735 Shared_DirtyCardQ_lock, 1736 NULL, // fl_owner 1737 true); // init_free_ids 1738 1739 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon, 1740 DirtyCardQ_FL_lock, 1741 -1, // never trigger processing 1742 -1, // no limit on length 1743 Shared_DirtyCardQ_lock, 1744 &JavaThread::dirty_card_queue_set()); 1745 1746 // Here we allocate the dummy HeapRegion that is required by the 1747 // G1AllocRegion class. 1748 HeapRegion* dummy_region = _hrm.get_dummy_region(); 1749 1750 // We'll re-use the same region whether the alloc region will 1751 // require BOT updates or not and, if it doesn't, then a non-young 1752 // region will complain that it cannot support allocations without 1753 // BOT updates. So we'll tag the dummy region as eden to avoid that. 1754 dummy_region->set_eden(); 1755 // Make sure it's full. 1756 dummy_region->set_top(dummy_region->end()); 1757 G1AllocRegion::setup(this, dummy_region); 1758 1759 _allocator->init_mutator_alloc_region(); 1760 1761 // Do create of the monitoring and management support so that 1762 // values in the heap have been properly initialized. 1763 _g1mm = new G1MonitoringSupport(this); 1764 1765 G1StringDedup::initialize(); 1766 1767 _preserved_marks_set.init(ParallelGCThreads); 1768 1769 _collection_set.initialize(max_regions()); 1770 1771 return JNI_OK; 1772 } 1773 1774 void G1CollectedHeap::initialize_serviceability() { 1775 _eden_pool = new G1EdenPool(this); 1776 _survivor_pool = new G1SurvivorPool(this); 1777 _old_pool = new G1OldGenPool(this); 1778 1779 _full_gc_memory_manager.add_pool(_eden_pool); 1780 _full_gc_memory_manager.add_pool(_survivor_pool); 1781 _full_gc_memory_manager.add_pool(_old_pool); 1782 1783 _memory_manager.add_pool(_eden_pool); 1784 _memory_manager.add_pool(_survivor_pool); 1785 1786 } 1787 1788 void G1CollectedHeap::stop() { 1789 // Stop all concurrent threads. We do this to make sure these threads 1790 // do not continue to execute and access resources (e.g. logging) 1791 // that are destroyed during shutdown. 1792 _cr->stop(); 1793 _young_gen_sampling_thread->stop(); 1794 _cmThread->stop(); 1795 if (G1StringDedup::is_enabled()) { 1796 G1StringDedup::stop(); 1797 } 1798 } 1799 1800 void G1CollectedHeap::safepoint_synchronize_begin() { 1801 SuspendibleThreadSet::synchronize(); 1802 } 1803 1804 void G1CollectedHeap::safepoint_synchronize_end() { 1805 SuspendibleThreadSet::desynchronize(); 1806 } 1807 1808 size_t G1CollectedHeap::conservative_max_heap_alignment() { 1809 return HeapRegion::max_region_size(); 1810 } 1811 1812 void G1CollectedHeap::post_initialize() { 1813 CollectedHeap::post_initialize(); 1814 ref_processing_init(); 1815 } 1816 1817 void G1CollectedHeap::ref_processing_init() { 1818 // Reference processing in G1 currently works as follows: 1819 // 1820 // * There are two reference processor instances. One is 1821 // used to record and process discovered references 1822 // during concurrent marking; the other is used to 1823 // record and process references during STW pauses 1824 // (both full and incremental). 1825 // * Both ref processors need to 'span' the entire heap as 1826 // the regions in the collection set may be dotted around. 1827 // 1828 // * For the concurrent marking ref processor: 1829 // * Reference discovery is enabled at initial marking. 1830 // * Reference discovery is disabled and the discovered 1831 // references processed etc during remarking. 1832 // * Reference discovery is MT (see below). 1833 // * Reference discovery requires a barrier (see below). 1834 // * Reference processing may or may not be MT 1835 // (depending on the value of ParallelRefProcEnabled 1836 // and ParallelGCThreads). 1837 // * A full GC disables reference discovery by the CM 1838 // ref processor and abandons any entries on it's 1839 // discovered lists. 1840 // 1841 // * For the STW processor: 1842 // * Non MT discovery is enabled at the start of a full GC. 1843 // * Processing and enqueueing during a full GC is non-MT. 1844 // * During a full GC, references are processed after marking. 1845 // 1846 // * Discovery (may or may not be MT) is enabled at the start 1847 // of an incremental evacuation pause. 1848 // * References are processed near the end of a STW evacuation pause. 1849 // * For both types of GC: 1850 // * Discovery is atomic - i.e. not concurrent. 1851 // * Reference discovery will not need a barrier. 1852 1853 MemRegion mr = reserved_region(); 1854 1855 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1); 1856 1857 // Concurrent Mark ref processor 1858 _ref_processor_cm = 1859 new ReferenceProcessor(mr, // span 1860 mt_processing, 1861 // mt processing 1862 ParallelGCThreads, 1863 // degree of mt processing 1864 (ParallelGCThreads > 1) || (ConcGCThreads > 1), 1865 // mt discovery 1866 MAX2(ParallelGCThreads, ConcGCThreads), 1867 // degree of mt discovery 1868 false, 1869 // Reference discovery is not atomic 1870 &_is_alive_closure_cm); 1871 // is alive closure 1872 // (for efficiency/performance) 1873 1874 // STW ref processor 1875 _ref_processor_stw = 1876 new ReferenceProcessor(mr, // span 1877 mt_processing, 1878 // mt processing 1879 ParallelGCThreads, 1880 // degree of mt processing 1881 (ParallelGCThreads > 1), 1882 // mt discovery 1883 ParallelGCThreads, 1884 // degree of mt discovery 1885 true, 1886 // Reference discovery is atomic 1887 &_is_alive_closure_stw); 1888 // is alive closure 1889 // (for efficiency/performance) 1890 } 1891 1892 CollectorPolicy* G1CollectedHeap::collector_policy() const { 1893 return _collector_policy; 1894 } 1895 1896 size_t G1CollectedHeap::capacity() const { 1897 return _hrm.length() * HeapRegion::GrainBytes; 1898 } 1899 1900 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const { 1901 return _hrm.total_free_bytes(); 1902 } 1903 1904 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) { 1905 hr->reset_gc_time_stamp(); 1906 } 1907 1908 #ifndef PRODUCT 1909 1910 class CheckGCTimeStampsHRClosure : public HeapRegionClosure { 1911 private: 1912 unsigned _gc_time_stamp; 1913 bool _failures; 1914 1915 public: 1916 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) : 1917 _gc_time_stamp(gc_time_stamp), _failures(false) { } 1918 1919 virtual bool do_heap_region(HeapRegion* hr) { 1920 unsigned region_gc_time_stamp = hr->get_gc_time_stamp(); 1921 if (_gc_time_stamp != region_gc_time_stamp) { 1922 log_error(gc, verify)("Region " HR_FORMAT " has GC time stamp = %d, expected %d", HR_FORMAT_PARAMS(hr), 1923 region_gc_time_stamp, _gc_time_stamp); 1924 _failures = true; 1925 } 1926 return false; 1927 } 1928 1929 bool failures() { return _failures; } 1930 }; 1931 1932 void G1CollectedHeap::check_gc_time_stamps() { 1933 CheckGCTimeStampsHRClosure cl(_gc_time_stamp); 1934 heap_region_iterate(&cl); 1935 guarantee(!cl.failures(), "all GC time stamps should have been reset"); 1936 } 1937 #endif // PRODUCT 1938 1939 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) { 1940 _hot_card_cache->drain(cl, worker_i); 1941 } 1942 1943 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) { 1944 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 1945 size_t n_completed_buffers = 0; 1946 while (dcqs.apply_closure_during_gc(cl, worker_i)) { 1947 n_completed_buffers++; 1948 } 1949 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers); 1950 dcqs.clear_n_completed_buffers(); 1951 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!"); 1952 } 1953 1954 // Computes the sum of the storage used by the various regions. 1955 size_t G1CollectedHeap::used() const { 1956 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions(); 1957 if (_archive_allocator != NULL) { 1958 result += _archive_allocator->used(); 1959 } 1960 return result; 1961 } 1962 1963 size_t G1CollectedHeap::used_unlocked() const { 1964 return _summary_bytes_used; 1965 } 1966 1967 class SumUsedClosure: public HeapRegionClosure { 1968 size_t _used; 1969 public: 1970 SumUsedClosure() : _used(0) {} 1971 bool do_heap_region(HeapRegion* r) { 1972 _used += r->used(); 1973 return false; 1974 } 1975 size_t result() { return _used; } 1976 }; 1977 1978 size_t G1CollectedHeap::recalculate_used() const { 1979 double recalculate_used_start = os::elapsedTime(); 1980 1981 SumUsedClosure blk; 1982 heap_region_iterate(&blk); 1983 1984 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0); 1985 return blk.result(); 1986 } 1987 1988 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) { 1989 switch (cause) { 1990 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent; 1991 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent; 1992 case GCCause::_update_allocation_context_stats_inc: return true; 1993 case GCCause::_wb_conc_mark: return true; 1994 default : return false; 1995 } 1996 } 1997 1998 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 1999 switch (cause) { 2000 case GCCause::_gc_locker: return GCLockerInvokesConcurrent; 2001 case GCCause::_g1_humongous_allocation: return true; 2002 default: return is_user_requested_concurrent_full_gc(cause); 2003 } 2004 } 2005 2006 #ifndef PRODUCT 2007 void G1CollectedHeap::allocate_dummy_regions() { 2008 // Let's fill up most of the region 2009 size_t word_size = HeapRegion::GrainWords - 1024; 2010 // And as a result the region we'll allocate will be humongous. 2011 guarantee(is_humongous(word_size), "sanity"); 2012 2013 // _filler_array_max_size is set to humongous object threshold 2014 // but temporarily change it to use CollectedHeap::fill_with_object(). 2015 SizeTFlagSetting fs(_filler_array_max_size, word_size); 2016 2017 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) { 2018 // Let's use the existing mechanism for the allocation 2019 HeapWord* dummy_obj = humongous_obj_allocate(word_size, 2020 AllocationContext::system()); 2021 if (dummy_obj != NULL) { 2022 MemRegion mr(dummy_obj, word_size); 2023 CollectedHeap::fill_with_object(mr); 2024 } else { 2025 // If we can't allocate once, we probably cannot allocate 2026 // again. Let's get out of the loop. 2027 break; 2028 } 2029 } 2030 } 2031 #endif // !PRODUCT 2032 2033 void G1CollectedHeap::increment_old_marking_cycles_started() { 2034 assert(_old_marking_cycles_started == _old_marking_cycles_completed || 2035 _old_marking_cycles_started == _old_marking_cycles_completed + 1, 2036 "Wrong marking cycle count (started: %d, completed: %d)", 2037 _old_marking_cycles_started, _old_marking_cycles_completed); 2038 2039 _old_marking_cycles_started++; 2040 } 2041 2042 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) { 2043 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 2044 2045 // We assume that if concurrent == true, then the caller is a 2046 // concurrent thread that was joined the Suspendible Thread 2047 // Set. If there's ever a cheap way to check this, we should add an 2048 // assert here. 2049 2050 // Given that this method is called at the end of a Full GC or of a 2051 // concurrent cycle, and those can be nested (i.e., a Full GC can 2052 // interrupt a concurrent cycle), the number of full collections 2053 // completed should be either one (in the case where there was no 2054 // nesting) or two (when a Full GC interrupted a concurrent cycle) 2055 // behind the number of full collections started. 2056 2057 // This is the case for the inner caller, i.e. a Full GC. 2058 assert(concurrent || 2059 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || 2060 (_old_marking_cycles_started == _old_marking_cycles_completed + 2), 2061 "for inner caller (Full GC): _old_marking_cycles_started = %u " 2062 "is inconsistent with _old_marking_cycles_completed = %u", 2063 _old_marking_cycles_started, _old_marking_cycles_completed); 2064 2065 // This is the case for the outer caller, i.e. the concurrent cycle. 2066 assert(!concurrent || 2067 (_old_marking_cycles_started == _old_marking_cycles_completed + 1), 2068 "for outer caller (concurrent cycle): " 2069 "_old_marking_cycles_started = %u " 2070 "is inconsistent with _old_marking_cycles_completed = %u", 2071 _old_marking_cycles_started, _old_marking_cycles_completed); 2072 2073 _old_marking_cycles_completed += 1; 2074 2075 // We need to clear the "in_progress" flag in the CM thread before 2076 // we wake up any waiters (especially when ExplicitInvokesConcurrent 2077 // is set) so that if a waiter requests another System.gc() it doesn't 2078 // incorrectly see that a marking cycle is still in progress. 2079 if (concurrent) { 2080 _cmThread->set_idle(); 2081 } 2082 2083 // This notify_all() will ensure that a thread that called 2084 // System.gc() with (with ExplicitGCInvokesConcurrent set or not) 2085 // and it's waiting for a full GC to finish will be woken up. It is 2086 // waiting in VM_G1CollectForAllocation::doit_epilogue(). 2087 FullGCCount_lock->notify_all(); 2088 } 2089 2090 void G1CollectedHeap::collect(GCCause::Cause cause) { 2091 assert_heap_not_locked(); 2092 2093 uint gc_count_before; 2094 uint old_marking_count_before; 2095 uint full_gc_count_before; 2096 bool retry_gc; 2097 2098 do { 2099 retry_gc = false; 2100 2101 { 2102 MutexLocker ml(Heap_lock); 2103 2104 // Read the GC count while holding the Heap_lock 2105 gc_count_before = total_collections(); 2106 full_gc_count_before = total_full_collections(); 2107 old_marking_count_before = _old_marking_cycles_started; 2108 } 2109 2110 if (should_do_concurrent_full_gc(cause)) { 2111 // Schedule an initial-mark evacuation pause that will start a 2112 // concurrent cycle. We're setting word_size to 0 which means that 2113 // we are not requesting a post-GC allocation. 2114 VM_G1CollectForAllocation op(0, /* word_size */ 2115 gc_count_before, 2116 cause, 2117 true, /* should_initiate_conc_mark */ 2118 g1_policy()->max_pause_time_ms(), 2119 AllocationContext::current()); 2120 VMThread::execute(&op); 2121 if (!op.pause_succeeded()) { 2122 if (old_marking_count_before == _old_marking_cycles_started) { 2123 retry_gc = op.should_retry_gc(); 2124 } else { 2125 // A Full GC happened while we were trying to schedule the 2126 // initial-mark GC. No point in starting a new cycle given 2127 // that the whole heap was collected anyway. 2128 } 2129 2130 if (retry_gc) { 2131 if (GCLocker::is_active_and_needs_gc()) { 2132 GCLocker::stall_until_clear(); 2133 } 2134 } 2135 } 2136 } else { 2137 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc 2138 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { 2139 2140 // Schedule a standard evacuation pause. We're setting word_size 2141 // to 0 which means that we are not requesting a post-GC allocation. 2142 VM_G1CollectForAllocation op(0, /* word_size */ 2143 gc_count_before, 2144 cause, 2145 false, /* should_initiate_conc_mark */ 2146 g1_policy()->max_pause_time_ms(), 2147 AllocationContext::current()); 2148 VMThread::execute(&op); 2149 } else { 2150 // Schedule a Full GC. 2151 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause); 2152 VMThread::execute(&op); 2153 } 2154 } 2155 } while (retry_gc); 2156 } 2157 2158 bool G1CollectedHeap::is_in(const void* p) const { 2159 if (_hrm.reserved().contains(p)) { 2160 // Given that we know that p is in the reserved space, 2161 // heap_region_containing() should successfully 2162 // return the containing region. 2163 HeapRegion* hr = heap_region_containing(p); 2164 return hr->is_in(p); 2165 } else { 2166 return false; 2167 } 2168 } 2169 2170 #ifdef ASSERT 2171 bool G1CollectedHeap::is_in_exact(const void* p) const { 2172 bool contains = reserved_region().contains(p); 2173 bool available = _hrm.is_available(addr_to_region((HeapWord*)p)); 2174 if (contains && available) { 2175 return true; 2176 } else { 2177 return false; 2178 } 2179 } 2180 #endif 2181 2182 // Iteration functions. 2183 2184 // Iterates an ObjectClosure over all objects within a HeapRegion. 2185 2186 class IterateObjectClosureRegionClosure: public HeapRegionClosure { 2187 ObjectClosure* _cl; 2188 public: 2189 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} 2190 bool do_heap_region(HeapRegion* r) { 2191 if (!r->is_continues_humongous()) { 2192 r->object_iterate(_cl); 2193 } 2194 return false; 2195 } 2196 }; 2197 2198 void G1CollectedHeap::object_iterate(ObjectClosure* cl) { 2199 IterateObjectClosureRegionClosure blk(cl); 2200 heap_region_iterate(&blk); 2201 } 2202 2203 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { 2204 _hrm.iterate(cl); 2205 } 2206 2207 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl, 2208 HeapRegionClaimer *hrclaimer, 2209 uint worker_id) const { 2210 _hrm.par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id)); 2211 } 2212 2213 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl, 2214 HeapRegionClaimer *hrclaimer) const { 2215 _hrm.par_iterate(cl, hrclaimer, 0); 2216 } 2217 2218 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) { 2219 _collection_set.iterate(cl); 2220 } 2221 2222 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) { 2223 _collection_set.iterate_from(cl, worker_id, workers()->active_workers()); 2224 } 2225 2226 HeapWord* G1CollectedHeap::block_start(const void* addr) const { 2227 HeapRegion* hr = heap_region_containing(addr); 2228 return hr->block_start(addr); 2229 } 2230 2231 size_t G1CollectedHeap::block_size(const HeapWord* addr) const { 2232 HeapRegion* hr = heap_region_containing(addr); 2233 return hr->block_size(addr); 2234 } 2235 2236 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { 2237 HeapRegion* hr = heap_region_containing(addr); 2238 return hr->block_is_obj(addr); 2239 } 2240 2241 bool G1CollectedHeap::supports_tlab_allocation() const { 2242 return true; 2243 } 2244 2245 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { 2246 return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes; 2247 } 2248 2249 size_t G1CollectedHeap::tlab_used(Thread* ignored) const { 2250 return _eden.length() * HeapRegion::GrainBytes; 2251 } 2252 2253 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size 2254 // must be equal to the humongous object limit. 2255 size_t G1CollectedHeap::max_tlab_size() const { 2256 return align_down(_humongous_object_threshold_in_words, MinObjAlignment); 2257 } 2258 2259 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { 2260 AllocationContext_t context = AllocationContext::current(); 2261 return _allocator->unsafe_max_tlab_alloc(context); 2262 } 2263 2264 size_t G1CollectedHeap::max_capacity() const { 2265 return _hrm.reserved().byte_size(); 2266 } 2267 2268 jlong G1CollectedHeap::millis_since_last_gc() { 2269 // See the notes in GenCollectedHeap::millis_since_last_gc() 2270 // for more information about the implementation. 2271 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) - 2272 _g1_policy->collection_pause_end_millis(); 2273 if (ret_val < 0) { 2274 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT 2275 ". returning zero instead.", ret_val); 2276 return 0; 2277 } 2278 return ret_val; 2279 } 2280 2281 void G1CollectedHeap::prepare_for_verify() { 2282 _verifier->prepare_for_verify(); 2283 } 2284 2285 void G1CollectedHeap::verify(VerifyOption vo) { 2286 _verifier->verify(vo); 2287 } 2288 2289 bool G1CollectedHeap::supports_concurrent_phase_control() const { 2290 return true; 2291 } 2292 2293 const char* const* G1CollectedHeap::concurrent_phases() const { 2294 return _cmThread->concurrent_phases(); 2295 } 2296 2297 bool G1CollectedHeap::request_concurrent_phase(const char* phase) { 2298 return _cmThread->request_concurrent_phase(phase); 2299 } 2300 2301 class PrintRegionClosure: public HeapRegionClosure { 2302 outputStream* _st; 2303 public: 2304 PrintRegionClosure(outputStream* st) : _st(st) {} 2305 bool do_heap_region(HeapRegion* r) { 2306 r->print_on(_st); 2307 return false; 2308 } 2309 }; 2310 2311 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2312 const HeapRegion* hr, 2313 const VerifyOption vo) const { 2314 switch (vo) { 2315 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); 2316 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); 2317 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr); 2318 default: ShouldNotReachHere(); 2319 } 2320 return false; // keep some compilers happy 2321 } 2322 2323 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2324 const VerifyOption vo) const { 2325 switch (vo) { 2326 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); 2327 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); 2328 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj); 2329 default: ShouldNotReachHere(); 2330 } 2331 return false; // keep some compilers happy 2332 } 2333 2334 void G1CollectedHeap::print_heap_regions() const { 2335 LogTarget(Trace, gc, heap, region) lt; 2336 if (lt.is_enabled()) { 2337 LogStream ls(lt); 2338 print_regions_on(&ls); 2339 } 2340 } 2341 2342 void G1CollectedHeap::print_on(outputStream* st) const { 2343 st->print(" %-20s", "garbage-first heap"); 2344 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 2345 capacity()/K, used_unlocked()/K); 2346 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")", 2347 p2i(_hrm.reserved().start()), 2348 p2i(_hrm.reserved().end())); 2349 st->cr(); 2350 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); 2351 uint young_regions = young_regions_count(); 2352 st->print("%u young (" SIZE_FORMAT "K), ", young_regions, 2353 (size_t) young_regions * HeapRegion::GrainBytes / K); 2354 uint survivor_regions = survivor_regions_count(); 2355 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, 2356 (size_t) survivor_regions * HeapRegion::GrainBytes / K); 2357 st->cr(); 2358 MetaspaceAux::print_on(st); 2359 } 2360 2361 void G1CollectedHeap::print_regions_on(outputStream* st) const { 2362 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, " 2363 "HS=humongous(starts), HC=humongous(continues), " 2364 "CS=collection set, F=free, A=archive, TS=gc time stamp, " 2365 "AC=allocation context, " 2366 "TAMS=top-at-mark-start (previous, next)"); 2367 PrintRegionClosure blk(st); 2368 heap_region_iterate(&blk); 2369 } 2370 2371 void G1CollectedHeap::print_extended_on(outputStream* st) const { 2372 print_on(st); 2373 2374 // Print the per-region information. 2375 print_regions_on(st); 2376 } 2377 2378 void G1CollectedHeap::print_on_error(outputStream* st) const { 2379 this->CollectedHeap::print_on_error(st); 2380 2381 if (_cm != NULL) { 2382 st->cr(); 2383 _cm->print_on_error(st); 2384 } 2385 } 2386 2387 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const { 2388 workers()->print_worker_threads_on(st); 2389 _cmThread->print_on(st); 2390 st->cr(); 2391 _cm->print_worker_threads_on(st); 2392 _cr->print_threads_on(st); 2393 _young_gen_sampling_thread->print_on(st); 2394 if (G1StringDedup::is_enabled()) { 2395 G1StringDedup::print_worker_threads_on(st); 2396 } 2397 } 2398 2399 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { 2400 workers()->threads_do(tc); 2401 tc->do_thread(_cmThread); 2402 _cm->threads_do(tc); 2403 _cr->threads_do(tc); 2404 tc->do_thread(_young_gen_sampling_thread); 2405 if (G1StringDedup::is_enabled()) { 2406 G1StringDedup::threads_do(tc); 2407 } 2408 } 2409 2410 void G1CollectedHeap::print_tracing_info() const { 2411 g1_rem_set()->print_summary_info(); 2412 concurrent_mark()->print_summary_info(); 2413 } 2414 2415 #ifndef PRODUCT 2416 // Helpful for debugging RSet issues. 2417 2418 class PrintRSetsClosure : public HeapRegionClosure { 2419 private: 2420 const char* _msg; 2421 size_t _occupied_sum; 2422 2423 public: 2424 bool do_heap_region(HeapRegion* r) { 2425 HeapRegionRemSet* hrrs = r->rem_set(); 2426 size_t occupied = hrrs->occupied(); 2427 _occupied_sum += occupied; 2428 2429 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r)); 2430 if (occupied == 0) { 2431 tty->print_cr(" RSet is empty"); 2432 } else { 2433 hrrs->print(); 2434 } 2435 tty->print_cr("----------"); 2436 return false; 2437 } 2438 2439 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { 2440 tty->cr(); 2441 tty->print_cr("========================================"); 2442 tty->print_cr("%s", msg); 2443 tty->cr(); 2444 } 2445 2446 ~PrintRSetsClosure() { 2447 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum); 2448 tty->print_cr("========================================"); 2449 tty->cr(); 2450 } 2451 }; 2452 2453 void G1CollectedHeap::print_cset_rsets() { 2454 PrintRSetsClosure cl("Printing CSet RSets"); 2455 collection_set_iterate(&cl); 2456 } 2457 2458 void G1CollectedHeap::print_all_rsets() { 2459 PrintRSetsClosure cl("Printing All RSets");; 2460 heap_region_iterate(&cl); 2461 } 2462 #endif // PRODUCT 2463 2464 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() { 2465 2466 size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes; 2467 size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes; 2468 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked(); 2469 2470 size_t eden_capacity_bytes = 2471 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes; 2472 2473 VirtualSpaceSummary heap_summary = create_heap_space_summary(); 2474 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes, 2475 eden_capacity_bytes, survivor_used_bytes, num_regions()); 2476 } 2477 2478 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) { 2479 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(), 2480 stats->unused(), stats->used(), stats->region_end_waste(), 2481 stats->regions_filled(), stats->direct_allocated(), 2482 stats->failure_used(), stats->failure_waste()); 2483 } 2484 2485 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) { 2486 const G1HeapSummary& heap_summary = create_g1_heap_summary(); 2487 gc_tracer->report_gc_heap_summary(when, heap_summary); 2488 2489 const MetaspaceSummary& metaspace_summary = create_metaspace_summary(); 2490 gc_tracer->report_metaspace_summary(when, metaspace_summary); 2491 } 2492 2493 G1CollectedHeap* G1CollectedHeap::heap() { 2494 CollectedHeap* heap = Universe::heap(); 2495 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()"); 2496 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap"); 2497 return (G1CollectedHeap*)heap; 2498 } 2499 2500 void G1CollectedHeap::gc_prologue(bool full) { 2501 // always_do_update_barrier = false; 2502 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 2503 2504 // This summary needs to be printed before incrementing total collections. 2505 g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections()); 2506 2507 // Update common counters. 2508 increment_total_collections(full /* full gc */); 2509 if (full) { 2510 increment_old_marking_cycles_started(); 2511 reset_gc_time_stamp(); 2512 } else { 2513 increment_gc_time_stamp(); 2514 } 2515 2516 // Fill TLAB's and such 2517 double start = os::elapsedTime(); 2518 accumulate_statistics_all_tlabs(); 2519 ensure_parsability(true); 2520 g1_policy()->phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0); 2521 } 2522 2523 void G1CollectedHeap::gc_epilogue(bool full) { 2524 // Update common counters. 2525 if (full) { 2526 // Update the number of full collections that have been completed. 2527 increment_old_marking_cycles_completed(false /* concurrent */); 2528 } 2529 2530 // We are at the end of the GC. Total collections has already been increased. 2531 g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1); 2532 2533 // FIXME: what is this about? 2534 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" 2535 // is set. 2536 #if COMPILER2_OR_JVMCI 2537 assert(DerivedPointerTable::is_empty(), "derived pointer present"); 2538 #endif 2539 // always_do_update_barrier = true; 2540 2541 double start = os::elapsedTime(); 2542 resize_all_tlabs(); 2543 g1_policy()->phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0); 2544 2545 allocation_context_stats().update(full); 2546 2547 MemoryService::track_memory_usage(); 2548 // We have just completed a GC. Update the soft reference 2549 // policy with the new heap occupancy 2550 Universe::update_heap_info_at_gc(); 2551 } 2552 2553 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, 2554 uint gc_count_before, 2555 bool* succeeded, 2556 GCCause::Cause gc_cause) { 2557 assert_heap_not_locked_and_not_at_safepoint(); 2558 VM_G1CollectForAllocation op(word_size, 2559 gc_count_before, 2560 gc_cause, 2561 false, /* should_initiate_conc_mark */ 2562 g1_policy()->max_pause_time_ms(), 2563 AllocationContext::current()); 2564 VMThread::execute(&op); 2565 2566 HeapWord* result = op.result(); 2567 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded(); 2568 assert(result == NULL || ret_succeeded, 2569 "the result should be NULL if the VM did not succeed"); 2570 *succeeded = ret_succeeded; 2571 2572 assert_heap_not_locked(); 2573 return result; 2574 } 2575 2576 void 2577 G1CollectedHeap::doConcurrentMark() { 2578 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); 2579 if (!_cmThread->in_progress()) { 2580 _cmThread->set_started(); 2581 CGC_lock->notify(); 2582 } 2583 } 2584 2585 size_t G1CollectedHeap::pending_card_num() { 2586 size_t extra_cards = 0; 2587 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *curr = jtiwh.next(); ) { 2588 DirtyCardQueue& dcq = curr->dirty_card_queue(); 2589 extra_cards += dcq.size(); 2590 } 2591 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 2592 size_t buffer_size = dcqs.buffer_size(); 2593 size_t buffer_num = dcqs.completed_buffers_num(); 2594 2595 return buffer_size * buffer_num + extra_cards; 2596 } 2597 2598 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure { 2599 private: 2600 size_t _total_humongous; 2601 size_t _candidate_humongous; 2602 2603 DirtyCardQueue _dcq; 2604 2605 // We don't nominate objects with many remembered set entries, on 2606 // the assumption that such objects are likely still live. 2607 bool is_remset_small(HeapRegion* region) const { 2608 HeapRegionRemSet* const rset = region->rem_set(); 2609 return G1EagerReclaimHumongousObjectsWithStaleRefs 2610 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) 2611 : rset->is_empty(); 2612 } 2613 2614 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const { 2615 assert(region->is_starts_humongous(), "Must start a humongous object"); 2616 2617 oop obj = oop(region->bottom()); 2618 2619 // Dead objects cannot be eager reclaim candidates. Due to class 2620 // unloading it is unsafe to query their classes so we return early. 2621 if (heap->is_obj_dead(obj, region)) { 2622 return false; 2623 } 2624 2625 // Candidate selection must satisfy the following constraints 2626 // while concurrent marking is in progress: 2627 // 2628 // * In order to maintain SATB invariants, an object must not be 2629 // reclaimed if it was allocated before the start of marking and 2630 // has not had its references scanned. Such an object must have 2631 // its references (including type metadata) scanned to ensure no 2632 // live objects are missed by the marking process. Objects 2633 // allocated after the start of concurrent marking don't need to 2634 // be scanned. 2635 // 2636 // * An object must not be reclaimed if it is on the concurrent 2637 // mark stack. Objects allocated after the start of concurrent 2638 // marking are never pushed on the mark stack. 2639 // 2640 // Nominating only objects allocated after the start of concurrent 2641 // marking is sufficient to meet both constraints. This may miss 2642 // some objects that satisfy the constraints, but the marking data 2643 // structures don't support efficiently performing the needed 2644 // additional tests or scrubbing of the mark stack. 2645 // 2646 // However, we presently only nominate is_typeArray() objects. 2647 // A humongous object containing references induces remembered 2648 // set entries on other regions. In order to reclaim such an 2649 // object, those remembered sets would need to be cleaned up. 2650 // 2651 // We also treat is_typeArray() objects specially, allowing them 2652 // to be reclaimed even if allocated before the start of 2653 // concurrent mark. For this we rely on mark stack insertion to 2654 // exclude is_typeArray() objects, preventing reclaiming an object 2655 // that is in the mark stack. We also rely on the metadata for 2656 // such objects to be built-in and so ensured to be kept live. 2657 // Frequent allocation and drop of large binary blobs is an 2658 // important use case for eager reclaim, and this special handling 2659 // may reduce needed headroom. 2660 2661 return obj->is_typeArray() && is_remset_small(region); 2662 } 2663 2664 public: 2665 RegisterHumongousWithInCSetFastTestClosure() 2666 : _total_humongous(0), 2667 _candidate_humongous(0), 2668 _dcq(&JavaThread::dirty_card_queue_set()) { 2669 } 2670 2671 virtual bool do_heap_region(HeapRegion* r) { 2672 if (!r->is_starts_humongous()) { 2673 return false; 2674 } 2675 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 2676 2677 bool is_candidate = humongous_region_is_candidate(g1h, r); 2678 uint rindex = r->hrm_index(); 2679 g1h->set_humongous_reclaim_candidate(rindex, is_candidate); 2680 if (is_candidate) { 2681 _candidate_humongous++; 2682 g1h->register_humongous_region_with_cset(rindex); 2683 // Is_candidate already filters out humongous object with large remembered sets. 2684 // If we have a humongous object with a few remembered sets, we simply flush these 2685 // remembered set entries into the DCQS. That will result in automatic 2686 // re-evaluation of their remembered set entries during the following evacuation 2687 // phase. 2688 if (!r->rem_set()->is_empty()) { 2689 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries), 2690 "Found a not-small remembered set here. This is inconsistent with previous assumptions."); 2691 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set(); 2692 HeapRegionRemSetIterator hrrs(r->rem_set()); 2693 size_t card_index; 2694 while (hrrs.has_next(card_index)) { 2695 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index); 2696 // The remembered set might contain references to already freed 2697 // regions. Filter out such entries to avoid failing card table 2698 // verification. 2699 if (g1h->is_in_closed_subset(bs->addr_for(card_ptr))) { 2700 if (*card_ptr != CardTableModRefBS::dirty_card_val()) { 2701 *card_ptr = CardTableModRefBS::dirty_card_val(); 2702 _dcq.enqueue(card_ptr); 2703 } 2704 } 2705 } 2706 assert(hrrs.n_yielded() == r->rem_set()->occupied(), 2707 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries", 2708 hrrs.n_yielded(), r->rem_set()->occupied()); 2709 r->rem_set()->clear_locked(); 2710 } 2711 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty."); 2712 } 2713 _total_humongous++; 2714 2715 return false; 2716 } 2717 2718 size_t total_humongous() const { return _total_humongous; } 2719 size_t candidate_humongous() const { return _candidate_humongous; } 2720 2721 void flush_rem_set_entries() { _dcq.flush(); } 2722 }; 2723 2724 void G1CollectedHeap::register_humongous_regions_with_cset() { 2725 if (!G1EagerReclaimHumongousObjects) { 2726 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0); 2727 return; 2728 } 2729 double time = os::elapsed_counter(); 2730 2731 // Collect reclaim candidate information and register candidates with cset. 2732 RegisterHumongousWithInCSetFastTestClosure cl; 2733 heap_region_iterate(&cl); 2734 2735 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0; 2736 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time, 2737 cl.total_humongous(), 2738 cl.candidate_humongous()); 2739 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0; 2740 2741 // Finally flush all remembered set entries to re-check into the global DCQS. 2742 cl.flush_rem_set_entries(); 2743 } 2744 2745 class VerifyRegionRemSetClosure : public HeapRegionClosure { 2746 public: 2747 bool do_heap_region(HeapRegion* hr) { 2748 if (!hr->is_archive() && !hr->is_continues_humongous()) { 2749 hr->verify_rem_set(); 2750 } 2751 return false; 2752 } 2753 }; 2754 2755 uint G1CollectedHeap::num_task_queues() const { 2756 return _task_queues->size(); 2757 } 2758 2759 #if TASKQUEUE_STATS 2760 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) { 2761 st->print_raw_cr("GC Task Stats"); 2762 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); 2763 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); 2764 } 2765 2766 void G1CollectedHeap::print_taskqueue_stats() const { 2767 if (!log_is_enabled(Trace, gc, task, stats)) { 2768 return; 2769 } 2770 Log(gc, task, stats) log; 2771 ResourceMark rm; 2772 LogStream ls(log.trace()); 2773 outputStream* st = &ls; 2774 2775 print_taskqueue_stats_hdr(st); 2776 2777 TaskQueueStats totals; 2778 const uint n = num_task_queues(); 2779 for (uint i = 0; i < n; ++i) { 2780 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr(); 2781 totals += task_queue(i)->stats; 2782 } 2783 st->print_raw("tot "); totals.print(st); st->cr(); 2784 2785 DEBUG_ONLY(totals.verify()); 2786 } 2787 2788 void G1CollectedHeap::reset_taskqueue_stats() { 2789 const uint n = num_task_queues(); 2790 for (uint i = 0; i < n; ++i) { 2791 task_queue(i)->stats.reset(); 2792 } 2793 } 2794 #endif // TASKQUEUE_STATS 2795 2796 void G1CollectedHeap::wait_for_root_region_scanning() { 2797 double scan_wait_start = os::elapsedTime(); 2798 // We have to wait until the CM threads finish scanning the 2799 // root regions as it's the only way to ensure that all the 2800 // objects on them have been correctly scanned before we start 2801 // moving them during the GC. 2802 bool waited = _cm->root_regions()->wait_until_scan_finished(); 2803 double wait_time_ms = 0.0; 2804 if (waited) { 2805 double scan_wait_end = os::elapsedTime(); 2806 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0; 2807 } 2808 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms); 2809 } 2810 2811 class G1PrintCollectionSetClosure : public HeapRegionClosure { 2812 private: 2813 G1HRPrinter* _hr_printer; 2814 public: 2815 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { } 2816 2817 virtual bool do_heap_region(HeapRegion* r) { 2818 _hr_printer->cset(r); 2819 return false; 2820 } 2821 }; 2822 2823 void G1CollectedHeap::start_new_collection_set() { 2824 collection_set()->start_incremental_building(); 2825 2826 clear_cset_fast_test(); 2827 2828 guarantee(_eden.length() == 0, "eden should have been cleared"); 2829 g1_policy()->transfer_survivors_to_cset(survivor()); 2830 } 2831 2832 bool 2833 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { 2834 assert_at_safepoint(true /* should_be_vm_thread */); 2835 guarantee(!is_gc_active(), "collection is not reentrant"); 2836 2837 if (GCLocker::check_active_before_gc()) { 2838 return false; 2839 } 2840 2841 _gc_timer_stw->register_gc_start(); 2842 2843 GCIdMark gc_id_mark; 2844 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start()); 2845 2846 SvcGCMarker sgcm(SvcGCMarker::MINOR); 2847 ResourceMark rm; 2848 2849 g1_policy()->note_gc_start(); 2850 2851 wait_for_root_region_scanning(); 2852 2853 print_heap_before_gc(); 2854 print_heap_regions(); 2855 trace_heap_before_gc(_gc_tracer_stw); 2856 2857 _verifier->verify_region_sets_optional(); 2858 _verifier->verify_dirty_young_regions(); 2859 2860 // We should not be doing initial mark unless the conc mark thread is running 2861 if (!_cmThread->should_terminate()) { 2862 // This call will decide whether this pause is an initial-mark 2863 // pause. If it is, during_initial_mark_pause() will return true 2864 // for the duration of this pause. 2865 g1_policy()->decide_on_conc_mark_initiation(); 2866 } 2867 2868 // We do not allow initial-mark to be piggy-backed on a mixed GC. 2869 assert(!collector_state()->during_initial_mark_pause() || 2870 collector_state()->gcs_are_young(), "sanity"); 2871 2872 // We also do not allow mixed GCs during marking. 2873 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity"); 2874 2875 // Record whether this pause is an initial mark. When the current 2876 // thread has completed its logging output and it's safe to signal 2877 // the CM thread, the flag's value in the policy has been reset. 2878 bool should_start_conc_mark = collector_state()->during_initial_mark_pause(); 2879 2880 // Inner scope for scope based logging, timers, and stats collection 2881 { 2882 EvacuationInfo evacuation_info; 2883 2884 if (collector_state()->during_initial_mark_pause()) { 2885 // We are about to start a marking cycle, so we increment the 2886 // full collection counter. 2887 increment_old_marking_cycles_started(); 2888 _cm->gc_tracer_cm()->set_gc_cause(gc_cause()); 2889 } 2890 2891 _gc_tracer_stw->report_yc_type(collector_state()->yc_type()); 2892 2893 GCTraceCPUTime tcpu; 2894 2895 G1HeapVerifier::G1VerifyType verify_type; 2896 FormatBuffer<> gc_string("Pause "); 2897 if (collector_state()->during_initial_mark_pause()) { 2898 gc_string.append("Initial Mark"); 2899 verify_type = G1HeapVerifier::G1VerifyInitialMark; 2900 } else if (collector_state()->gcs_are_young()) { 2901 gc_string.append("Young"); 2902 verify_type = G1HeapVerifier::G1VerifyYoungOnly; 2903 } else { 2904 gc_string.append("Mixed"); 2905 verify_type = G1HeapVerifier::G1VerifyMixed; 2906 } 2907 GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true); 2908 2909 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 2910 workers()->active_workers(), 2911 Threads::number_of_non_daemon_threads()); 2912 workers()->update_active_workers(active_workers); 2913 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers()); 2914 2915 TraceCollectorStats tcs(g1mm()->incremental_collection_counters()); 2916 TraceMemoryManagerStats tms(&_memory_manager, gc_cause()); 2917 2918 // If the secondary_free_list is not empty, append it to the 2919 // free_list. No need to wait for the cleanup operation to finish; 2920 // the region allocation code will check the secondary_free_list 2921 // and wait if necessary. If the G1StressConcRegionFreeing flag is 2922 // set, skip this step so that the region allocation code has to 2923 // get entries from the secondary_free_list. 2924 if (!G1StressConcRegionFreeing) { 2925 append_secondary_free_list_if_not_empty_with_lock(); 2926 } 2927 2928 G1HeapTransition heap_transition(this); 2929 size_t heap_used_bytes_before_gc = used(); 2930 2931 // Don't dynamically change the number of GC threads this early. A value of 2932 // 0 is used to indicate serial work. When parallel work is done, 2933 // it will be set. 2934 2935 { // Call to jvmpi::post_class_unload_events must occur outside of active GC 2936 IsGCActiveMark x; 2937 2938 gc_prologue(false); 2939 2940 if (VerifyRememberedSets) { 2941 log_info(gc, verify)("[Verifying RemSets before GC]"); 2942 VerifyRegionRemSetClosure v_cl; 2943 heap_region_iterate(&v_cl); 2944 } 2945 2946 _verifier->verify_before_gc(verify_type); 2947 2948 _verifier->check_bitmaps("GC Start"); 2949 2950 #if COMPILER2_OR_JVMCI 2951 DerivedPointerTable::clear(); 2952 #endif 2953 2954 // Please see comment in g1CollectedHeap.hpp and 2955 // G1CollectedHeap::ref_processing_init() to see how 2956 // reference processing currently works in G1. 2957 2958 // Enable discovery in the STW reference processor 2959 if (g1_policy()->should_process_references()) { 2960 ref_processor_stw()->enable_discovery(); 2961 } else { 2962 ref_processor_stw()->disable_discovery(); 2963 } 2964 2965 { 2966 // We want to temporarily turn off discovery by the 2967 // CM ref processor, if necessary, and turn it back on 2968 // on again later if we do. Using a scoped 2969 // NoRefDiscovery object will do this. 2970 NoRefDiscovery no_cm_discovery(ref_processor_cm()); 2971 2972 // Forget the current alloc region (we might even choose it to be part 2973 // of the collection set!). 2974 _allocator->release_mutator_alloc_region(); 2975 2976 // This timing is only used by the ergonomics to handle our pause target. 2977 // It is unclear why this should not include the full pause. We will 2978 // investigate this in CR 7178365. 2979 // 2980 // Preserving the old comment here if that helps the investigation: 2981 // 2982 // The elapsed time induced by the start time below deliberately elides 2983 // the possible verification above. 2984 double sample_start_time_sec = os::elapsedTime(); 2985 2986 g1_policy()->record_collection_pause_start(sample_start_time_sec); 2987 2988 if (collector_state()->during_initial_mark_pause()) { 2989 concurrent_mark()->checkpoint_roots_initial_pre(); 2990 } 2991 2992 g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor); 2993 2994 evacuation_info.set_collectionset_regions(collection_set()->region_length()); 2995 2996 // Make sure the remembered sets are up to date. This needs to be 2997 // done before register_humongous_regions_with_cset(), because the 2998 // remembered sets are used there to choose eager reclaim candidates. 2999 // If the remembered sets are not up to date we might miss some 3000 // entries that need to be handled. 3001 g1_rem_set()->cleanupHRRS(); 3002 3003 register_humongous_regions_with_cset(); 3004 3005 assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table."); 3006 3007 // We call this after finalize_cset() to 3008 // ensure that the CSet has been finalized. 3009 _cm->verify_no_cset_oops(); 3010 3011 if (_hr_printer.is_active()) { 3012 G1PrintCollectionSetClosure cl(&_hr_printer); 3013 _collection_set.iterate(&cl); 3014 } 3015 3016 // Initialize the GC alloc regions. 3017 _allocator->init_gc_alloc_regions(evacuation_info); 3018 3019 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length()); 3020 pre_evacuate_collection_set(); 3021 3022 // Actually do the work... 3023 evacuate_collection_set(evacuation_info, &per_thread_states); 3024 3025 post_evacuate_collection_set(evacuation_info, &per_thread_states); 3026 3027 const size_t* surviving_young_words = per_thread_states.surviving_young_words(); 3028 free_collection_set(&_collection_set, evacuation_info, surviving_young_words); 3029 3030 eagerly_reclaim_humongous_regions(); 3031 3032 record_obj_copy_mem_stats(); 3033 _survivor_evac_stats.adjust_desired_plab_sz(); 3034 _old_evac_stats.adjust_desired_plab_sz(); 3035 3036 double start = os::elapsedTime(); 3037 start_new_collection_set(); 3038 g1_policy()->phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0); 3039 3040 if (evacuation_failed()) { 3041 set_used(recalculate_used()); 3042 if (_archive_allocator != NULL) { 3043 _archive_allocator->clear_used(); 3044 } 3045 for (uint i = 0; i < ParallelGCThreads; i++) { 3046 if (_evacuation_failed_info_array[i].has_failed()) { 3047 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]); 3048 } 3049 } 3050 } else { 3051 // The "used" of the the collection set have already been subtracted 3052 // when they were freed. Add in the bytes evacuated. 3053 increase_used(g1_policy()->bytes_copied_during_gc()); 3054 } 3055 3056 if (collector_state()->during_initial_mark_pause()) { 3057 // We have to do this before we notify the CM threads that 3058 // they can start working to make sure that all the 3059 // appropriate initialization is done on the CM object. 3060 concurrent_mark()->checkpoint_roots_initial_post(); 3061 collector_state()->set_mark_in_progress(true); 3062 // Note that we don't actually trigger the CM thread at 3063 // this point. We do that later when we're sure that 3064 // the current thread has completed its logging output. 3065 } 3066 3067 allocate_dummy_regions(); 3068 3069 _allocator->init_mutator_alloc_region(); 3070 3071 { 3072 size_t expand_bytes = _heap_sizing_policy->expansion_amount(); 3073 if (expand_bytes > 0) { 3074 size_t bytes_before = capacity(); 3075 // No need for an ergo logging here, 3076 // expansion_amount() does this when it returns a value > 0. 3077 double expand_ms; 3078 if (!expand(expand_bytes, _workers, &expand_ms)) { 3079 // We failed to expand the heap. Cannot do anything about it. 3080 } 3081 g1_policy()->phase_times()->record_expand_heap_time(expand_ms); 3082 } 3083 } 3084 3085 // We redo the verification but now wrt to the new CSet which 3086 // has just got initialized after the previous CSet was freed. 3087 _cm->verify_no_cset_oops(); 3088 3089 // This timing is only used by the ergonomics to handle our pause target. 3090 // It is unclear why this should not include the full pause. We will 3091 // investigate this in CR 7178365. 3092 double sample_end_time_sec = os::elapsedTime(); 3093 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; 3094 size_t total_cards_scanned = g1_policy()->phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScanRSScannedCards); 3095 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc); 3096 3097 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before()); 3098 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc()); 3099 3100 if (VerifyRememberedSets) { 3101 log_info(gc, verify)("[Verifying RemSets after GC]"); 3102 VerifyRegionRemSetClosure v_cl; 3103 heap_region_iterate(&v_cl); 3104 } 3105 3106 _verifier->verify_after_gc(verify_type); 3107 _verifier->check_bitmaps("GC End"); 3108 3109 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 3110 ref_processor_stw()->verify_no_references_recorded(); 3111 3112 // CM reference discovery will be re-enabled if necessary. 3113 } 3114 3115 #ifdef TRACESPINNING 3116 ParallelTaskTerminator::print_termination_counts(); 3117 #endif 3118 3119 gc_epilogue(false); 3120 } 3121 3122 // Print the remainder of the GC log output. 3123 if (evacuation_failed()) { 3124 log_info(gc)("To-space exhausted"); 3125 } 3126 3127 g1_policy()->print_phases(); 3128 heap_transition.print(); 3129 3130 // It is not yet to safe to tell the concurrent mark to 3131 // start as we have some optional output below. We don't want the 3132 // output from the concurrent mark thread interfering with this 3133 // logging output either. 3134 3135 _hrm.verify_optional(); 3136 _verifier->verify_region_sets_optional(); 3137 3138 TASKQUEUE_STATS_ONLY(print_taskqueue_stats()); 3139 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); 3140 3141 print_heap_after_gc(); 3142 print_heap_regions(); 3143 trace_heap_after_gc(_gc_tracer_stw); 3144 3145 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 3146 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 3147 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 3148 // before any GC notifications are raised. 3149 g1mm()->update_sizes(); 3150 3151 _gc_tracer_stw->report_evacuation_info(&evacuation_info); 3152 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold()); 3153 _gc_timer_stw->register_gc_end(); 3154 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions()); 3155 } 3156 // It should now be safe to tell the concurrent mark thread to start 3157 // without its logging output interfering with the logging output 3158 // that came from the pause. 3159 3160 if (should_start_conc_mark) { 3161 // CAUTION: after the doConcurrentMark() call below, 3162 // the concurrent marking thread(s) could be running 3163 // concurrently with us. Make sure that anything after 3164 // this point does not assume that we are the only GC thread 3165 // running. Note: of course, the actual marking work will 3166 // not start until the safepoint itself is released in 3167 // SuspendibleThreadSet::desynchronize(). 3168 doConcurrentMark(); 3169 } 3170 3171 return true; 3172 } 3173 3174 void G1CollectedHeap::remove_self_forwarding_pointers() { 3175 G1ParRemoveSelfForwardPtrsTask rsfp_task; 3176 workers()->run_task(&rsfp_task); 3177 } 3178 3179 void G1CollectedHeap::restore_after_evac_failure() { 3180 double remove_self_forwards_start = os::elapsedTime(); 3181 3182 remove_self_forwarding_pointers(); 3183 SharedRestorePreservedMarksTaskExecutor task_executor(workers()); 3184 _preserved_marks_set.restore(&task_executor); 3185 3186 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0); 3187 } 3188 3189 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) { 3190 if (!_evacuation_failed) { 3191 _evacuation_failed = true; 3192 } 3193 3194 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size()); 3195 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m); 3196 } 3197 3198 bool G1ParEvacuateFollowersClosure::offer_termination() { 3199 G1ParScanThreadState* const pss = par_scan_state(); 3200 start_term_time(); 3201 const bool res = terminator()->offer_termination(); 3202 end_term_time(); 3203 return res; 3204 } 3205 3206 void G1ParEvacuateFollowersClosure::do_void() { 3207 G1ParScanThreadState* const pss = par_scan_state(); 3208 pss->trim_queue(); 3209 do { 3210 pss->steal_and_trim_queue(queues()); 3211 } while (!offer_termination()); 3212 } 3213 3214 class G1ParTask : public AbstractGangTask { 3215 protected: 3216 G1CollectedHeap* _g1h; 3217 G1ParScanThreadStateSet* _pss; 3218 RefToScanQueueSet* _queues; 3219 G1RootProcessor* _root_processor; 3220 ParallelTaskTerminator _terminator; 3221 uint _n_workers; 3222 3223 public: 3224 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers) 3225 : AbstractGangTask("G1 collection"), 3226 _g1h(g1h), 3227 _pss(per_thread_states), 3228 _queues(task_queues), 3229 _root_processor(root_processor), 3230 _terminator(n_workers, _queues), 3231 _n_workers(n_workers) 3232 {} 3233 3234 void work(uint worker_id) { 3235 if (worker_id >= _n_workers) return; // no work needed this round 3236 3237 double start_sec = os::elapsedTime(); 3238 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec); 3239 3240 { 3241 ResourceMark rm; 3242 HandleMark hm; 3243 3244 ReferenceProcessor* rp = _g1h->ref_processor_stw(); 3245 3246 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 3247 pss->set_ref_processor(rp); 3248 3249 double start_strong_roots_sec = os::elapsedTime(); 3250 3251 _root_processor->evacuate_roots(pss->closures(), worker_id); 3252 3253 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid 3254 // treating the nmethods visited to act as roots for concurrent marking. 3255 // We only want to make sure that the oops in the nmethods are adjusted with regard to the 3256 // objects copied by the current evacuation. 3257 _g1h->g1_rem_set()->oops_into_collection_set_do(pss, 3258 pss->closures()->weak_codeblobs(), 3259 worker_id); 3260 3261 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec; 3262 3263 double term_sec = 0.0; 3264 size_t evac_term_attempts = 0; 3265 { 3266 double start = os::elapsedTime(); 3267 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator); 3268 evac.do_void(); 3269 3270 evac_term_attempts = evac.term_attempts(); 3271 term_sec = evac.term_time(); 3272 double elapsed_sec = os::elapsedTime() - start; 3273 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec); 3274 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec); 3275 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts); 3276 } 3277 3278 assert(pss->queue_is_empty(), "should be empty"); 3279 3280 if (log_is_enabled(Debug, gc, task, stats)) { 3281 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); 3282 size_t lab_waste; 3283 size_t lab_undo_waste; 3284 pss->waste(lab_waste, lab_undo_waste); 3285 _g1h->print_termination_stats(worker_id, 3286 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */ 3287 strong_roots_sec * 1000.0, /* strong roots time */ 3288 term_sec * 1000.0, /* evac term time */ 3289 evac_term_attempts, /* evac term attempts */ 3290 lab_waste, /* alloc buffer waste */ 3291 lab_undo_waste /* undo waste */ 3292 ); 3293 } 3294 3295 // Close the inner scope so that the ResourceMark and HandleMark 3296 // destructors are executed here and are included as part of the 3297 // "GC Worker Time". 3298 } 3299 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime()); 3300 } 3301 }; 3302 3303 void G1CollectedHeap::print_termination_stats_hdr() { 3304 log_debug(gc, task, stats)("GC Termination Stats"); 3305 log_debug(gc, task, stats)(" elapsed --strong roots-- -------termination------- ------waste (KiB)------"); 3306 log_debug(gc, task, stats)("thr ms ms %% ms %% attempts total alloc undo"); 3307 log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------"); 3308 } 3309 3310 void G1CollectedHeap::print_termination_stats(uint worker_id, 3311 double elapsed_ms, 3312 double strong_roots_ms, 3313 double term_ms, 3314 size_t term_attempts, 3315 size_t alloc_buffer_waste, 3316 size_t undo_waste) const { 3317 log_debug(gc, task, stats) 3318 ("%3d %9.2f %9.2f %6.2f " 3319 "%9.2f %6.2f " SIZE_FORMAT_W(8) " " 3320 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7), 3321 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms, 3322 term_ms, term_ms * 100 / elapsed_ms, term_attempts, 3323 (alloc_buffer_waste + undo_waste) * HeapWordSize / K, 3324 alloc_buffer_waste * HeapWordSize / K, 3325 undo_waste * HeapWordSize / K); 3326 } 3327 3328 class G1StringAndSymbolCleaningTask : public AbstractGangTask { 3329 private: 3330 BoolObjectClosure* _is_alive; 3331 G1StringDedupUnlinkOrOopsDoClosure _dedup_closure; 3332 3333 int _initial_string_table_size; 3334 int _initial_symbol_table_size; 3335 3336 bool _process_strings; 3337 int _strings_processed; 3338 int _strings_removed; 3339 3340 bool _process_symbols; 3341 int _symbols_processed; 3342 int _symbols_removed; 3343 3344 bool _process_string_dedup; 3345 3346 public: 3347 G1StringAndSymbolCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool process_string_dedup) : 3348 AbstractGangTask("String/Symbol Unlinking"), 3349 _is_alive(is_alive), 3350 _dedup_closure(is_alive, NULL, false), 3351 _process_strings(process_strings), _strings_processed(0), _strings_removed(0), 3352 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0), 3353 _process_string_dedup(process_string_dedup) { 3354 3355 _initial_string_table_size = StringTable::the_table()->table_size(); 3356 _initial_symbol_table_size = SymbolTable::the_table()->table_size(); 3357 if (process_strings) { 3358 StringTable::clear_parallel_claimed_index(); 3359 } 3360 if (process_symbols) { 3361 SymbolTable::clear_parallel_claimed_index(); 3362 } 3363 } 3364 3365 ~G1StringAndSymbolCleaningTask() { 3366 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size, 3367 "claim value %d after unlink less than initial string table size %d", 3368 StringTable::parallel_claimed_index(), _initial_string_table_size); 3369 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size, 3370 "claim value %d after unlink less than initial symbol table size %d", 3371 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size); 3372 3373 log_info(gc, stringtable)( 3374 "Cleaned string and symbol table, " 3375 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, " 3376 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed", 3377 strings_processed(), strings_removed(), 3378 symbols_processed(), symbols_removed()); 3379 } 3380 3381 void work(uint worker_id) { 3382 int strings_processed = 0; 3383 int strings_removed = 0; 3384 int symbols_processed = 0; 3385 int symbols_removed = 0; 3386 if (_process_strings) { 3387 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed); 3388 Atomic::add(strings_processed, &_strings_processed); 3389 Atomic::add(strings_removed, &_strings_removed); 3390 } 3391 if (_process_symbols) { 3392 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed); 3393 Atomic::add(symbols_processed, &_symbols_processed); 3394 Atomic::add(symbols_removed, &_symbols_removed); 3395 } 3396 if (_process_string_dedup) { 3397 G1StringDedup::parallel_unlink(&_dedup_closure, worker_id); 3398 } 3399 } 3400 3401 size_t strings_processed() const { return (size_t)_strings_processed; } 3402 size_t strings_removed() const { return (size_t)_strings_removed; } 3403 3404 size_t symbols_processed() const { return (size_t)_symbols_processed; } 3405 size_t symbols_removed() const { return (size_t)_symbols_removed; } 3406 }; 3407 3408 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC { 3409 private: 3410 static Monitor* _lock; 3411 3412 BoolObjectClosure* const _is_alive; 3413 const bool _unloading_occurred; 3414 const uint _num_workers; 3415 3416 // Variables used to claim nmethods. 3417 CompiledMethod* _first_nmethod; 3418 CompiledMethod* volatile _claimed_nmethod; 3419 3420 // The list of nmethods that need to be processed by the second pass. 3421 CompiledMethod* volatile _postponed_list; 3422 volatile uint _num_entered_barrier; 3423 3424 public: 3425 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) : 3426 _is_alive(is_alive), 3427 _unloading_occurred(unloading_occurred), 3428 _num_workers(num_workers), 3429 _first_nmethod(NULL), 3430 _claimed_nmethod(NULL), 3431 _postponed_list(NULL), 3432 _num_entered_barrier(0) 3433 { 3434 CompiledMethod::increase_unloading_clock(); 3435 // Get first alive nmethod 3436 CompiledMethodIterator iter = CompiledMethodIterator(); 3437 if(iter.next_alive()) { 3438 _first_nmethod = iter.method(); 3439 } 3440 _claimed_nmethod = _first_nmethod; 3441 } 3442 3443 ~G1CodeCacheUnloadingTask() { 3444 CodeCache::verify_clean_inline_caches(); 3445 3446 CodeCache::set_needs_cache_clean(false); 3447 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be"); 3448 3449 CodeCache::verify_icholder_relocations(); 3450 } 3451 3452 private: 3453 void add_to_postponed_list(CompiledMethod* nm) { 3454 CompiledMethod* old; 3455 do { 3456 old = _postponed_list; 3457 nm->set_unloading_next(old); 3458 } while (Atomic::cmpxchg(nm, &_postponed_list, old) != old); 3459 } 3460 3461 void clean_nmethod(CompiledMethod* nm) { 3462 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred); 3463 3464 if (postponed) { 3465 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet. 3466 add_to_postponed_list(nm); 3467 } 3468 3469 // Mark that this thread has been cleaned/unloaded. 3470 // After this call, it will be safe to ask if this nmethod was unloaded or not. 3471 nm->set_unloading_clock(CompiledMethod::global_unloading_clock()); 3472 } 3473 3474 void clean_nmethod_postponed(CompiledMethod* nm) { 3475 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred); 3476 } 3477 3478 static const int MaxClaimNmethods = 16; 3479 3480 void claim_nmethods(CompiledMethod** claimed_nmethods, int *num_claimed_nmethods) { 3481 CompiledMethod* first; 3482 CompiledMethodIterator last; 3483 3484 do { 3485 *num_claimed_nmethods = 0; 3486 3487 first = _claimed_nmethod; 3488 last = CompiledMethodIterator(first); 3489 3490 if (first != NULL) { 3491 3492 for (int i = 0; i < MaxClaimNmethods; i++) { 3493 if (!last.next_alive()) { 3494 break; 3495 } 3496 claimed_nmethods[i] = last.method(); 3497 (*num_claimed_nmethods)++; 3498 } 3499 } 3500 3501 } while (Atomic::cmpxchg(last.method(), &_claimed_nmethod, first) != first); 3502 } 3503 3504 CompiledMethod* claim_postponed_nmethod() { 3505 CompiledMethod* claim; 3506 CompiledMethod* next; 3507 3508 do { 3509 claim = _postponed_list; 3510 if (claim == NULL) { 3511 return NULL; 3512 } 3513 3514 next = claim->unloading_next(); 3515 3516 } while (Atomic::cmpxchg(next, &_postponed_list, claim) != claim); 3517 3518 return claim; 3519 } 3520 3521 public: 3522 // Mark that we're done with the first pass of nmethod cleaning. 3523 void barrier_mark(uint worker_id) { 3524 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 3525 _num_entered_barrier++; 3526 if (_num_entered_barrier == _num_workers) { 3527 ml.notify_all(); 3528 } 3529 } 3530 3531 // See if we have to wait for the other workers to 3532 // finish their first-pass nmethod cleaning work. 3533 void barrier_wait(uint worker_id) { 3534 if (_num_entered_barrier < _num_workers) { 3535 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 3536 while (_num_entered_barrier < _num_workers) { 3537 ml.wait(Mutex::_no_safepoint_check_flag, 0, false); 3538 } 3539 } 3540 } 3541 3542 // Cleaning and unloading of nmethods. Some work has to be postponed 3543 // to the second pass, when we know which nmethods survive. 3544 void work_first_pass(uint worker_id) { 3545 // The first nmethods is claimed by the first worker. 3546 if (worker_id == 0 && _first_nmethod != NULL) { 3547 clean_nmethod(_first_nmethod); 3548 _first_nmethod = NULL; 3549 } 3550 3551 int num_claimed_nmethods; 3552 CompiledMethod* claimed_nmethods[MaxClaimNmethods]; 3553 3554 while (true) { 3555 claim_nmethods(claimed_nmethods, &num_claimed_nmethods); 3556 3557 if (num_claimed_nmethods == 0) { 3558 break; 3559 } 3560 3561 for (int i = 0; i < num_claimed_nmethods; i++) { 3562 clean_nmethod(claimed_nmethods[i]); 3563 } 3564 } 3565 } 3566 3567 void work_second_pass(uint worker_id) { 3568 CompiledMethod* nm; 3569 // Take care of postponed nmethods. 3570 while ((nm = claim_postponed_nmethod()) != NULL) { 3571 clean_nmethod_postponed(nm); 3572 } 3573 } 3574 }; 3575 3576 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never); 3577 3578 class G1KlassCleaningTask : public StackObj { 3579 BoolObjectClosure* _is_alive; 3580 volatile int _clean_klass_tree_claimed; 3581 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator; 3582 3583 public: 3584 G1KlassCleaningTask(BoolObjectClosure* is_alive) : 3585 _is_alive(is_alive), 3586 _clean_klass_tree_claimed(0), 3587 _klass_iterator() { 3588 } 3589 3590 private: 3591 bool claim_clean_klass_tree_task() { 3592 if (_clean_klass_tree_claimed) { 3593 return false; 3594 } 3595 3596 return Atomic::cmpxchg(1, &_clean_klass_tree_claimed, 0) == 0; 3597 } 3598 3599 InstanceKlass* claim_next_klass() { 3600 Klass* klass; 3601 do { 3602 klass =_klass_iterator.next_klass(); 3603 } while (klass != NULL && !klass->is_instance_klass()); 3604 3605 // this can be null so don't call InstanceKlass::cast 3606 return static_cast<InstanceKlass*>(klass); 3607 } 3608 3609 public: 3610 3611 void clean_klass(InstanceKlass* ik) { 3612 ik->clean_weak_instanceklass_links(_is_alive); 3613 } 3614 3615 void work() { 3616 ResourceMark rm; 3617 3618 // One worker will clean the subklass/sibling klass tree. 3619 if (claim_clean_klass_tree_task()) { 3620 Klass::clean_subklass_tree(_is_alive); 3621 } 3622 3623 // All workers will help cleaning the classes, 3624 InstanceKlass* klass; 3625 while ((klass = claim_next_klass()) != NULL) { 3626 clean_klass(klass); 3627 } 3628 } 3629 }; 3630 3631 class G1ResolvedMethodCleaningTask : public StackObj { 3632 BoolObjectClosure* _is_alive; 3633 volatile int _resolved_method_task_claimed; 3634 public: 3635 G1ResolvedMethodCleaningTask(BoolObjectClosure* is_alive) : 3636 _is_alive(is_alive), _resolved_method_task_claimed(0) {} 3637 3638 bool claim_resolved_method_task() { 3639 if (_resolved_method_task_claimed) { 3640 return false; 3641 } 3642 return Atomic::cmpxchg(1, &_resolved_method_task_claimed, 0) == 0; 3643 } 3644 3645 // These aren't big, one thread can do it all. 3646 void work() { 3647 if (claim_resolved_method_task()) { 3648 ResolvedMethodTable::unlink(_is_alive); 3649 } 3650 } 3651 }; 3652 3653 3654 // To minimize the remark pause times, the tasks below are done in parallel. 3655 class G1ParallelCleaningTask : public AbstractGangTask { 3656 private: 3657 G1StringAndSymbolCleaningTask _string_symbol_task; 3658 G1CodeCacheUnloadingTask _code_cache_task; 3659 G1KlassCleaningTask _klass_cleaning_task; 3660 G1ResolvedMethodCleaningTask _resolved_method_cleaning_task; 3661 3662 public: 3663 // The constructor is run in the VMThread. 3664 G1ParallelCleaningTask(BoolObjectClosure* is_alive, uint num_workers, bool unloading_occurred) : 3665 AbstractGangTask("Parallel Cleaning"), 3666 _string_symbol_task(is_alive, true, true, G1StringDedup::is_enabled()), 3667 _code_cache_task(num_workers, is_alive, unloading_occurred), 3668 _klass_cleaning_task(is_alive), 3669 _resolved_method_cleaning_task(is_alive) { 3670 } 3671 3672 // The parallel work done by all worker threads. 3673 void work(uint worker_id) { 3674 // Do first pass of code cache cleaning. 3675 _code_cache_task.work_first_pass(worker_id); 3676 3677 // Let the threads mark that the first pass is done. 3678 _code_cache_task.barrier_mark(worker_id); 3679 3680 // Clean the Strings and Symbols. 3681 _string_symbol_task.work(worker_id); 3682 3683 // Clean unreferenced things in the ResolvedMethodTable 3684 _resolved_method_cleaning_task.work(); 3685 3686 // Wait for all workers to finish the first code cache cleaning pass. 3687 _code_cache_task.barrier_wait(worker_id); 3688 3689 // Do the second code cache cleaning work, which realize on 3690 // the liveness information gathered during the first pass. 3691 _code_cache_task.work_second_pass(worker_id); 3692 3693 // Clean all klasses that were not unloaded. 3694 _klass_cleaning_task.work(); 3695 } 3696 }; 3697 3698 3699 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive, 3700 bool class_unloading_occurred) { 3701 uint n_workers = workers()->active_workers(); 3702 3703 G1ParallelCleaningTask g1_unlink_task(is_alive, n_workers, class_unloading_occurred); 3704 workers()->run_task(&g1_unlink_task); 3705 } 3706 3707 void G1CollectedHeap::partial_cleaning(BoolObjectClosure* is_alive, 3708 bool process_strings, 3709 bool process_symbols, 3710 bool process_string_dedup) { 3711 if (!process_strings && !process_symbols && !process_string_dedup) { 3712 // Nothing to clean. 3713 return; 3714 } 3715 3716 G1StringAndSymbolCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, process_string_dedup); 3717 workers()->run_task(&g1_unlink_task); 3718 3719 } 3720 3721 class G1RedirtyLoggedCardsTask : public AbstractGangTask { 3722 private: 3723 DirtyCardQueueSet* _queue; 3724 G1CollectedHeap* _g1h; 3725 public: 3726 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"), 3727 _queue(queue), _g1h(g1h) { } 3728 3729 virtual void work(uint worker_id) { 3730 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times(); 3731 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id); 3732 3733 RedirtyLoggedCardTableEntryClosure cl(_g1h); 3734 _queue->par_apply_closure_to_all_completed_buffers(&cl); 3735 3736 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied()); 3737 } 3738 }; 3739 3740 void G1CollectedHeap::redirty_logged_cards() { 3741 double redirty_logged_cards_start = os::elapsedTime(); 3742 3743 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this); 3744 dirty_card_queue_set().reset_for_par_iteration(); 3745 workers()->run_task(&redirty_task); 3746 3747 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set(); 3748 dcq.merge_bufferlists(&dirty_card_queue_set()); 3749 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed"); 3750 3751 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0); 3752 } 3753 3754 // Weak Reference Processing support 3755 3756 // An always "is_alive" closure that is used to preserve referents. 3757 // If the object is non-null then it's alive. Used in the preservation 3758 // of referent objects that are pointed to by reference objects 3759 // discovered by the CM ref processor. 3760 class G1AlwaysAliveClosure: public BoolObjectClosure { 3761 G1CollectedHeap* _g1; 3762 public: 3763 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 3764 bool do_object_b(oop p) { 3765 if (p != NULL) { 3766 return true; 3767 } 3768 return false; 3769 } 3770 }; 3771 3772 bool G1STWIsAliveClosure::do_object_b(oop p) { 3773 // An object is reachable if it is outside the collection set, 3774 // or is inside and copied. 3775 return !_g1->is_in_cset(p) || p->is_forwarded(); 3776 } 3777 3778 // Non Copying Keep Alive closure 3779 class G1KeepAliveClosure: public OopClosure { 3780 G1CollectedHeap* _g1; 3781 public: 3782 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 3783 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } 3784 void do_oop(oop* p) { 3785 oop obj = *p; 3786 assert(obj != NULL, "the caller should have filtered out NULL values"); 3787 3788 const InCSetState cset_state = _g1->in_cset_state(obj); 3789 if (!cset_state.is_in_cset_or_humongous()) { 3790 return; 3791 } 3792 if (cset_state.is_in_cset()) { 3793 assert( obj->is_forwarded(), "invariant" ); 3794 *p = obj->forwardee(); 3795 } else { 3796 assert(!obj->is_forwarded(), "invariant" ); 3797 assert(cset_state.is_humongous(), 3798 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value()); 3799 _g1->set_humongous_is_live(obj); 3800 } 3801 } 3802 }; 3803 3804 // Copying Keep Alive closure - can be called from both 3805 // serial and parallel code as long as different worker 3806 // threads utilize different G1ParScanThreadState instances 3807 // and different queues. 3808 3809 class G1CopyingKeepAliveClosure: public OopClosure { 3810 G1CollectedHeap* _g1h; 3811 OopClosure* _copy_non_heap_obj_cl; 3812 G1ParScanThreadState* _par_scan_state; 3813 3814 public: 3815 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, 3816 OopClosure* non_heap_obj_cl, 3817 G1ParScanThreadState* pss): 3818 _g1h(g1h), 3819 _copy_non_heap_obj_cl(non_heap_obj_cl), 3820 _par_scan_state(pss) 3821 {} 3822 3823 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 3824 virtual void do_oop( oop* p) { do_oop_work(p); } 3825 3826 template <class T> void do_oop_work(T* p) { 3827 oop obj = oopDesc::load_decode_heap_oop(p); 3828 3829 if (_g1h->is_in_cset_or_humongous(obj)) { 3830 // If the referent object has been forwarded (either copied 3831 // to a new location or to itself in the event of an 3832 // evacuation failure) then we need to update the reference 3833 // field and, if both reference and referent are in the G1 3834 // heap, update the RSet for the referent. 3835 // 3836 // If the referent has not been forwarded then we have to keep 3837 // it alive by policy. Therefore we have copy the referent. 3838 // 3839 // If the reference field is in the G1 heap then we can push 3840 // on the PSS queue. When the queue is drained (after each 3841 // phase of reference processing) the object and it's followers 3842 // will be copied, the reference field set to point to the 3843 // new location, and the RSet updated. Otherwise we need to 3844 // use the the non-heap or metadata closures directly to copy 3845 // the referent object and update the pointer, while avoiding 3846 // updating the RSet. 3847 3848 if (_g1h->is_in_g1_reserved(p)) { 3849 _par_scan_state->push_on_queue(p); 3850 } else { 3851 assert(!Metaspace::contains((const void*)p), 3852 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p)); 3853 _copy_non_heap_obj_cl->do_oop(p); 3854 } 3855 } 3856 } 3857 }; 3858 3859 // Serial drain queue closure. Called as the 'complete_gc' 3860 // closure for each discovered list in some of the 3861 // reference processing phases. 3862 3863 class G1STWDrainQueueClosure: public VoidClosure { 3864 protected: 3865 G1CollectedHeap* _g1h; 3866 G1ParScanThreadState* _par_scan_state; 3867 3868 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 3869 3870 public: 3871 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : 3872 _g1h(g1h), 3873 _par_scan_state(pss) 3874 { } 3875 3876 void do_void() { 3877 G1ParScanThreadState* const pss = par_scan_state(); 3878 pss->trim_queue(); 3879 } 3880 }; 3881 3882 // Parallel Reference Processing closures 3883 3884 // Implementation of AbstractRefProcTaskExecutor for parallel reference 3885 // processing during G1 evacuation pauses. 3886 3887 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 3888 private: 3889 G1CollectedHeap* _g1h; 3890 G1ParScanThreadStateSet* _pss; 3891 RefToScanQueueSet* _queues; 3892 WorkGang* _workers; 3893 uint _active_workers; 3894 3895 public: 3896 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, 3897 G1ParScanThreadStateSet* per_thread_states, 3898 WorkGang* workers, 3899 RefToScanQueueSet *task_queues, 3900 uint n_workers) : 3901 _g1h(g1h), 3902 _pss(per_thread_states), 3903 _queues(task_queues), 3904 _workers(workers), 3905 _active_workers(n_workers) 3906 { 3907 g1h->ref_processor_stw()->set_active_mt_degree(n_workers); 3908 } 3909 3910 // Executes the given task using concurrent marking worker threads. 3911 virtual void execute(ProcessTask& task); 3912 virtual void execute(EnqueueTask& task); 3913 }; 3914 3915 // Gang task for possibly parallel reference processing 3916 3917 class G1STWRefProcTaskProxy: public AbstractGangTask { 3918 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 3919 ProcessTask& _proc_task; 3920 G1CollectedHeap* _g1h; 3921 G1ParScanThreadStateSet* _pss; 3922 RefToScanQueueSet* _task_queues; 3923 ParallelTaskTerminator* _terminator; 3924 3925 public: 3926 G1STWRefProcTaskProxy(ProcessTask& proc_task, 3927 G1CollectedHeap* g1h, 3928 G1ParScanThreadStateSet* per_thread_states, 3929 RefToScanQueueSet *task_queues, 3930 ParallelTaskTerminator* terminator) : 3931 AbstractGangTask("Process reference objects in parallel"), 3932 _proc_task(proc_task), 3933 _g1h(g1h), 3934 _pss(per_thread_states), 3935 _task_queues(task_queues), 3936 _terminator(terminator) 3937 {} 3938 3939 virtual void work(uint worker_id) { 3940 // The reference processing task executed by a single worker. 3941 ResourceMark rm; 3942 HandleMark hm; 3943 3944 G1STWIsAliveClosure is_alive(_g1h); 3945 3946 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 3947 pss->set_ref_processor(NULL); 3948 3949 // Keep alive closure. 3950 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss); 3951 3952 // Complete GC closure 3953 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator); 3954 3955 // Call the reference processing task's work routine. 3956 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); 3957 3958 // Note we cannot assert that the refs array is empty here as not all 3959 // of the processing tasks (specifically phase2 - pp2_work) execute 3960 // the complete_gc closure (which ordinarily would drain the queue) so 3961 // the queue may not be empty. 3962 } 3963 }; 3964 3965 // Driver routine for parallel reference processing. 3966 // Creates an instance of the ref processing gang 3967 // task and has the worker threads execute it. 3968 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) { 3969 assert(_workers != NULL, "Need parallel worker threads."); 3970 3971 ParallelTaskTerminator terminator(_active_workers, _queues); 3972 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator); 3973 3974 _workers->run_task(&proc_task_proxy); 3975 } 3976 3977 // Gang task for parallel reference enqueueing. 3978 3979 class G1STWRefEnqueueTaskProxy: public AbstractGangTask { 3980 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; 3981 EnqueueTask& _enq_task; 3982 3983 public: 3984 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) : 3985 AbstractGangTask("Enqueue reference objects in parallel"), 3986 _enq_task(enq_task) 3987 { } 3988 3989 virtual void work(uint worker_id) { 3990 _enq_task.work(worker_id); 3991 } 3992 }; 3993 3994 // Driver routine for parallel reference enqueueing. 3995 // Creates an instance of the ref enqueueing gang 3996 // task and has the worker threads execute it. 3997 3998 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) { 3999 assert(_workers != NULL, "Need parallel worker threads."); 4000 4001 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task); 4002 4003 _workers->run_task(&enq_task_proxy); 4004 } 4005 4006 // End of weak reference support closures 4007 4008 // Abstract task used to preserve (i.e. copy) any referent objects 4009 // that are in the collection set and are pointed to by reference 4010 // objects discovered by the CM ref processor. 4011 4012 class G1ParPreserveCMReferentsTask: public AbstractGangTask { 4013 protected: 4014 G1CollectedHeap* _g1h; 4015 G1ParScanThreadStateSet* _pss; 4016 RefToScanQueueSet* _queues; 4017 ParallelTaskTerminator _terminator; 4018 uint _n_workers; 4019 4020 public: 4021 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) : 4022 AbstractGangTask("ParPreserveCMReferents"), 4023 _g1h(g1h), 4024 _pss(per_thread_states), 4025 _queues(task_queues), 4026 _terminator(workers, _queues), 4027 _n_workers(workers) 4028 { 4029 g1h->ref_processor_cm()->set_active_mt_degree(workers); 4030 } 4031 4032 void work(uint worker_id) { 4033 G1GCParPhaseTimesTracker x(_g1h->g1_policy()->phase_times(), G1GCPhaseTimes::PreserveCMReferents, worker_id); 4034 4035 ResourceMark rm; 4036 HandleMark hm; 4037 4038 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 4039 pss->set_ref_processor(NULL); 4040 assert(pss->queue_is_empty(), "both queue and overflow should be empty"); 4041 4042 // Is alive closure 4043 G1AlwaysAliveClosure always_alive(_g1h); 4044 4045 // Copying keep alive closure. Applied to referent objects that need 4046 // to be copied. 4047 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss); 4048 4049 ReferenceProcessor* rp = _g1h->ref_processor_cm(); 4050 4051 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q(); 4052 uint stride = MIN2(MAX2(_n_workers, 1U), limit); 4053 4054 // limit is set using max_num_q() - which was set using ParallelGCThreads. 4055 // So this must be true - but assert just in case someone decides to 4056 // change the worker ids. 4057 assert(worker_id < limit, "sanity"); 4058 assert(!rp->discovery_is_atomic(), "check this code"); 4059 4060 // Select discovered lists [i, i+stride, i+2*stride,...,limit) 4061 for (uint idx = worker_id; idx < limit; idx += stride) { 4062 DiscoveredList& ref_list = rp->discovered_refs()[idx]; 4063 4064 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive); 4065 while (iter.has_next()) { 4066 // Since discovery is not atomic for the CM ref processor, we 4067 // can see some null referent objects. 4068 iter.load_ptrs(DEBUG_ONLY(true)); 4069 oop ref = iter.obj(); 4070 4071 // This will filter nulls. 4072 if (iter.is_referent_alive()) { 4073 iter.make_referent_alive(); 4074 } 4075 iter.move_to_next(); 4076 } 4077 } 4078 4079 // Drain the queue - which may cause stealing 4080 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator); 4081 drain_queue.do_void(); 4082 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure 4083 assert(pss->queue_is_empty(), "should be"); 4084 } 4085 }; 4086 4087 void G1CollectedHeap::preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states) { 4088 // Any reference objects, in the collection set, that were 'discovered' 4089 // by the CM ref processor should have already been copied (either by 4090 // applying the external root copy closure to the discovered lists, or 4091 // by following an RSet entry). 4092 // 4093 // But some of the referents, that are in the collection set, that these 4094 // reference objects point to may not have been copied: the STW ref 4095 // processor would have seen that the reference object had already 4096 // been 'discovered' and would have skipped discovering the reference, 4097 // but would not have treated the reference object as a regular oop. 4098 // As a result the copy closure would not have been applied to the 4099 // referent object. 4100 // 4101 // We need to explicitly copy these referent objects - the references 4102 // will be processed at the end of remarking. 4103 // 4104 // We also need to do this copying before we process the reference 4105 // objects discovered by the STW ref processor in case one of these 4106 // referents points to another object which is also referenced by an 4107 // object discovered by the STW ref processor. 4108 double preserve_cm_referents_time = 0.0; 4109 4110 // To avoid spawning task when there is no work to do, check that 4111 // a concurrent cycle is active and that some references have been 4112 // discovered. 4113 if (concurrent_mark()->cm_thread()->during_cycle() && 4114 ref_processor_cm()->has_discovered_references()) { 4115 double preserve_cm_referents_start = os::elapsedTime(); 4116 uint no_of_gc_workers = workers()->active_workers(); 4117 G1ParPreserveCMReferentsTask keep_cm_referents(this, 4118 per_thread_states, 4119 no_of_gc_workers, 4120 _task_queues); 4121 workers()->run_task(&keep_cm_referents); 4122 preserve_cm_referents_time = os::elapsedTime() - preserve_cm_referents_start; 4123 } 4124 4125 g1_policy()->phase_times()->record_preserve_cm_referents_time_ms(preserve_cm_referents_time * 1000.0); 4126 } 4127 4128 // Weak Reference processing during an evacuation pause (part 1). 4129 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) { 4130 double ref_proc_start = os::elapsedTime(); 4131 4132 ReferenceProcessor* rp = _ref_processor_stw; 4133 assert(rp->discovery_enabled(), "should have been enabled"); 4134 4135 // Closure to test whether a referent is alive. 4136 G1STWIsAliveClosure is_alive(this); 4137 4138 // Even when parallel reference processing is enabled, the processing 4139 // of JNI refs is serial and performed serially by the current thread 4140 // rather than by a worker. The following PSS will be used for processing 4141 // JNI refs. 4142 4143 // Use only a single queue for this PSS. 4144 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0); 4145 pss->set_ref_processor(NULL); 4146 assert(pss->queue_is_empty(), "pre-condition"); 4147 4148 // Keep alive closure. 4149 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss); 4150 4151 // Serial Complete GC closure 4152 G1STWDrainQueueClosure drain_queue(this, pss); 4153 4154 // Setup the soft refs policy... 4155 rp->setup_policy(false); 4156 4157 ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times(); 4158 4159 ReferenceProcessorStats stats; 4160 if (!rp->processing_is_mt()) { 4161 // Serial reference processing... 4162 stats = rp->process_discovered_references(&is_alive, 4163 &keep_alive, 4164 &drain_queue, 4165 NULL, 4166 pt); 4167 } else { 4168 uint no_of_gc_workers = workers()->active_workers(); 4169 4170 // Parallel reference processing 4171 assert(no_of_gc_workers <= rp->max_num_q(), 4172 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u", 4173 no_of_gc_workers, rp->max_num_q()); 4174 4175 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers); 4176 stats = rp->process_discovered_references(&is_alive, 4177 &keep_alive, 4178 &drain_queue, 4179 &par_task_executor, 4180 pt); 4181 } 4182 4183 _gc_tracer_stw->report_gc_reference_stats(stats); 4184 4185 // We have completed copying any necessary live referent objects. 4186 assert(pss->queue_is_empty(), "both queue and overflow should be empty"); 4187 4188 double ref_proc_time = os::elapsedTime() - ref_proc_start; 4189 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 4190 } 4191 4192 // Weak Reference processing during an evacuation pause (part 2). 4193 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) { 4194 double ref_enq_start = os::elapsedTime(); 4195 4196 ReferenceProcessor* rp = _ref_processor_stw; 4197 assert(!rp->discovery_enabled(), "should have been disabled as part of processing"); 4198 4199 ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times(); 4200 4201 // Now enqueue any remaining on the discovered lists on to 4202 // the pending list. 4203 if (!rp->processing_is_mt()) { 4204 // Serial reference processing... 4205 rp->enqueue_discovered_references(NULL, pt); 4206 } else { 4207 // Parallel reference enqueueing 4208 4209 uint n_workers = workers()->active_workers(); 4210 4211 assert(n_workers <= rp->max_num_q(), 4212 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u", 4213 n_workers, rp->max_num_q()); 4214 4215 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers); 4216 rp->enqueue_discovered_references(&par_task_executor, pt); 4217 } 4218 4219 rp->verify_no_references_recorded(); 4220 assert(!rp->discovery_enabled(), "should have been disabled"); 4221 4222 // If during an initial mark pause we install a pending list head which is not otherwise reachable 4223 // ensure that it is marked in the bitmap for concurrent marking to discover. 4224 if (collector_state()->during_initial_mark_pause()) { 4225 oop pll_head = Universe::reference_pending_list(); 4226 if (pll_head != NULL) { 4227 _cm->mark_in_next_bitmap(pll_head); 4228 } 4229 } 4230 4231 // FIXME 4232 // CM's reference processing also cleans up the string and symbol tables. 4233 // Should we do that here also? We could, but it is a serial operation 4234 // and could significantly increase the pause time. 4235 4236 double ref_enq_time = os::elapsedTime() - ref_enq_start; 4237 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0); 4238 } 4239 4240 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) { 4241 double merge_pss_time_start = os::elapsedTime(); 4242 per_thread_states->flush(); 4243 g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0); 4244 } 4245 4246 void G1CollectedHeap::pre_evacuate_collection_set() { 4247 _expand_heap_after_alloc_failure = true; 4248 _evacuation_failed = false; 4249 4250 // Disable the hot card cache. 4251 _hot_card_cache->reset_hot_cache_claimed_index(); 4252 _hot_card_cache->set_use_cache(false); 4253 4254 g1_rem_set()->prepare_for_oops_into_collection_set_do(); 4255 _preserved_marks_set.assert_empty(); 4256 4257 G1GCPhaseTimes* phase_times = g1_policy()->phase_times(); 4258 4259 // InitialMark needs claim bits to keep track of the marked-through CLDs. 4260 if (collector_state()->during_initial_mark_pause()) { 4261 double start_clear_claimed_marks = os::elapsedTime(); 4262 4263 ClassLoaderDataGraph::clear_claimed_marks(); 4264 4265 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0; 4266 phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms); 4267 } 4268 } 4269 4270 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) { 4271 // Should G1EvacuationFailureALot be in effect for this GC? 4272 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) 4273 4274 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty"); 4275 4276 G1GCPhaseTimes* phase_times = g1_policy()->phase_times(); 4277 4278 double start_par_time_sec = os::elapsedTime(); 4279 double end_par_time_sec; 4280 4281 { 4282 const uint n_workers = workers()->active_workers(); 4283 G1RootProcessor root_processor(this, n_workers); 4284 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers); 4285 4286 print_termination_stats_hdr(); 4287 4288 workers()->run_task(&g1_par_task); 4289 end_par_time_sec = os::elapsedTime(); 4290 4291 // Closing the inner scope will execute the destructor 4292 // for the G1RootProcessor object. We record the current 4293 // elapsed time before closing the scope so that time 4294 // taken for the destructor is NOT included in the 4295 // reported parallel time. 4296 } 4297 4298 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0; 4299 phase_times->record_par_time(par_time_ms); 4300 4301 double code_root_fixup_time_ms = 4302 (os::elapsedTime() - end_par_time_sec) * 1000.0; 4303 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms); 4304 } 4305 4306 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) { 4307 // Process any discovered reference objects - we have 4308 // to do this _before_ we retire the GC alloc regions 4309 // as we may have to copy some 'reachable' referent 4310 // objects (and their reachable sub-graphs) that were 4311 // not copied during the pause. 4312 if (g1_policy()->should_process_references()) { 4313 preserve_cm_referents(per_thread_states); 4314 process_discovered_references(per_thread_states); 4315 } else { 4316 ref_processor_stw()->verify_no_references_recorded(); 4317 } 4318 4319 G1STWIsAliveClosure is_alive(this); 4320 G1KeepAliveClosure keep_alive(this); 4321 4322 { 4323 double start = os::elapsedTime(); 4324 4325 WeakProcessor::weak_oops_do(&is_alive, &keep_alive); 4326 4327 double time_ms = (os::elapsedTime() - start) * 1000.0; 4328 g1_policy()->phase_times()->record_ref_proc_time(time_ms); 4329 } 4330 4331 if (G1StringDedup::is_enabled()) { 4332 double fixup_start = os::elapsedTime(); 4333 4334 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times()); 4335 4336 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0; 4337 g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms); 4338 } 4339 4340 g1_rem_set()->cleanup_after_oops_into_collection_set_do(); 4341 4342 if (evacuation_failed()) { 4343 restore_after_evac_failure(); 4344 4345 // Reset the G1EvacuationFailureALot counters and flags 4346 // Note: the values are reset only when an actual 4347 // evacuation failure occurs. 4348 NOT_PRODUCT(reset_evacuation_should_fail();) 4349 } 4350 4351 _preserved_marks_set.assert_empty(); 4352 4353 // Enqueue any remaining references remaining on the STW 4354 // reference processor's discovered lists. We need to do 4355 // this after the card table is cleaned (and verified) as 4356 // the act of enqueueing entries on to the pending list 4357 // will log these updates (and dirty their associated 4358 // cards). We need these updates logged to update any 4359 // RSets. 4360 if (g1_policy()->should_process_references()) { 4361 enqueue_discovered_references(per_thread_states); 4362 } else { 4363 g1_policy()->phase_times()->record_ref_enq_time(0); 4364 } 4365 4366 _allocator->release_gc_alloc_regions(evacuation_info); 4367 4368 merge_per_thread_state_info(per_thread_states); 4369 4370 // Reset and re-enable the hot card cache. 4371 // Note the counts for the cards in the regions in the 4372 // collection set are reset when the collection set is freed. 4373 _hot_card_cache->reset_hot_cache(); 4374 _hot_card_cache->set_use_cache(true); 4375 4376 purge_code_root_memory(); 4377 4378 redirty_logged_cards(); 4379 #if COMPILER2_OR_JVMCI 4380 double start = os::elapsedTime(); 4381 DerivedPointerTable::update_pointers(); 4382 g1_policy()->phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0); 4383 #endif 4384 g1_policy()->print_age_table(); 4385 } 4386 4387 void G1CollectedHeap::record_obj_copy_mem_stats() { 4388 g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize); 4389 4390 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats), 4391 create_g1_evac_summary(&_old_evac_stats)); 4392 } 4393 4394 void G1CollectedHeap::free_region(HeapRegion* hr, 4395 FreeRegionList* free_list, 4396 bool skip_remset, 4397 bool skip_hot_card_cache, 4398 bool locked) { 4399 assert(!hr->is_free(), "the region should not be free"); 4400 assert(!hr->is_empty(), "the region should not be empty"); 4401 assert(_hrm.is_available(hr->hrm_index()), "region should be committed"); 4402 assert(free_list != NULL, "pre-condition"); 4403 4404 if (G1VerifyBitmaps) { 4405 MemRegion mr(hr->bottom(), hr->end()); 4406 concurrent_mark()->clear_range_in_prev_bitmap(mr); 4407 } 4408 4409 // Clear the card counts for this region. 4410 // Note: we only need to do this if the region is not young 4411 // (since we don't refine cards in young regions). 4412 if (!skip_hot_card_cache && !hr->is_young()) { 4413 _hot_card_cache->reset_card_counts(hr); 4414 } 4415 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */); 4416 free_list->add_ordered(hr); 4417 } 4418 4419 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 4420 FreeRegionList* free_list, 4421 bool skip_remset) { 4422 assert(hr->is_humongous(), "this is only for humongous regions"); 4423 assert(free_list != NULL, "pre-condition"); 4424 hr->clear_humongous(); 4425 free_region(hr, free_list, skip_remset); 4426 } 4427 4428 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed, 4429 const uint humongous_regions_removed) { 4430 if (old_regions_removed > 0 || humongous_regions_removed > 0) { 4431 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 4432 _old_set.bulk_remove(old_regions_removed); 4433 _humongous_set.bulk_remove(humongous_regions_removed); 4434 } 4435 4436 } 4437 4438 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) { 4439 assert(list != NULL, "list can't be null"); 4440 if (!list->is_empty()) { 4441 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag); 4442 _hrm.insert_list_into_free_list(list); 4443 } 4444 } 4445 4446 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) { 4447 decrease_used(bytes); 4448 } 4449 4450 class G1ParScrubRemSetTask: public AbstractGangTask { 4451 protected: 4452 G1RemSet* _g1rs; 4453 HeapRegionClaimer _hrclaimer; 4454 4455 public: 4456 G1ParScrubRemSetTask(G1RemSet* g1_rs, uint num_workers) : 4457 AbstractGangTask("G1 ScrubRS"), 4458 _g1rs(g1_rs), 4459 _hrclaimer(num_workers) { 4460 } 4461 4462 void work(uint worker_id) { 4463 _g1rs->scrub(worker_id, &_hrclaimer); 4464 } 4465 }; 4466 4467 void G1CollectedHeap::scrub_rem_set() { 4468 uint num_workers = workers()->active_workers(); 4469 G1ParScrubRemSetTask g1_par_scrub_rs_task(g1_rem_set(), num_workers); 4470 workers()->run_task(&g1_par_scrub_rs_task); 4471 } 4472 4473 class G1FreeCollectionSetTask : public AbstractGangTask { 4474 private: 4475 4476 // Closure applied to all regions in the collection set to do work that needs to 4477 // be done serially in a single thread. 4478 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure { 4479 private: 4480 EvacuationInfo* _evacuation_info; 4481 const size_t* _surviving_young_words; 4482 4483 // Bytes used in successfully evacuated regions before the evacuation. 4484 size_t _before_used_bytes; 4485 // Bytes used in unsucessfully evacuated regions before the evacuation 4486 size_t _after_used_bytes; 4487 4488 size_t _bytes_allocated_in_old_since_last_gc; 4489 4490 size_t _failure_used_words; 4491 size_t _failure_waste_words; 4492 4493 FreeRegionList _local_free_list; 4494 public: 4495 G1SerialFreeCollectionSetClosure(EvacuationInfo* evacuation_info, const size_t* surviving_young_words) : 4496 HeapRegionClosure(), 4497 _evacuation_info(evacuation_info), 4498 _surviving_young_words(surviving_young_words), 4499 _before_used_bytes(0), 4500 _after_used_bytes(0), 4501 _bytes_allocated_in_old_since_last_gc(0), 4502 _failure_used_words(0), 4503 _failure_waste_words(0), 4504 _local_free_list("Local Region List for CSet Freeing") { 4505 } 4506 4507 virtual bool do_heap_region(HeapRegion* r) { 4508 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4509 4510 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index()); 4511 g1h->clear_in_cset(r); 4512 4513 if (r->is_young()) { 4514 assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(), 4515 "Young index %d is wrong for region %u of type %s with %u young regions", 4516 r->young_index_in_cset(), 4517 r->hrm_index(), 4518 r->get_type_str(), 4519 g1h->collection_set()->young_region_length()); 4520 size_t words_survived = _surviving_young_words[r->young_index_in_cset()]; 4521 r->record_surv_words_in_group(words_survived); 4522 } 4523 4524 if (!r->evacuation_failed()) { 4525 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index()); 4526 _before_used_bytes += r->used(); 4527 g1h->free_region(r, 4528 &_local_free_list, 4529 true, /* skip_remset */ 4530 true, /* skip_hot_card_cache */ 4531 true /* locked */); 4532 } else { 4533 r->uninstall_surv_rate_group(); 4534 r->set_young_index_in_cset(-1); 4535 r->set_evacuation_failed(false); 4536 // When moving a young gen region to old gen, we "allocate" that whole region 4537 // there. This is in addition to any already evacuated objects. Notify the 4538 // policy about that. 4539 // Old gen regions do not cause an additional allocation: both the objects 4540 // still in the region and the ones already moved are accounted for elsewhere. 4541 if (r->is_young()) { 4542 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes; 4543 } 4544 // The region is now considered to be old. 4545 r->set_old(); 4546 // Do some allocation statistics accounting. Regions that failed evacuation 4547 // are always made old, so there is no need to update anything in the young 4548 // gen statistics, but we need to update old gen statistics. 4549 size_t used_words = r->marked_bytes() / HeapWordSize; 4550 4551 _failure_used_words += used_words; 4552 _failure_waste_words += HeapRegion::GrainWords - used_words; 4553 4554 g1h->old_set_add(r); 4555 _after_used_bytes += r->used(); 4556 } 4557 return false; 4558 } 4559 4560 void complete_work() { 4561 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4562 4563 _evacuation_info->set_regions_freed(_local_free_list.length()); 4564 _evacuation_info->increment_collectionset_used_after(_after_used_bytes); 4565 4566 g1h->prepend_to_freelist(&_local_free_list); 4567 g1h->decrement_summary_bytes(_before_used_bytes); 4568 4569 G1Policy* policy = g1h->g1_policy(); 4570 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc); 4571 4572 g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words); 4573 } 4574 }; 4575 4576 G1CollectionSet* _collection_set; 4577 G1SerialFreeCollectionSetClosure _cl; 4578 const size_t* _surviving_young_words; 4579 4580 size_t _rs_lengths; 4581 4582 volatile jint _serial_work_claim; 4583 4584 struct WorkItem { 4585 uint region_idx; 4586 bool is_young; 4587 bool evacuation_failed; 4588 4589 WorkItem(HeapRegion* r) { 4590 region_idx = r->hrm_index(); 4591 is_young = r->is_young(); 4592 evacuation_failed = r->evacuation_failed(); 4593 } 4594 }; 4595 4596 volatile size_t _parallel_work_claim; 4597 size_t _num_work_items; 4598 WorkItem* _work_items; 4599 4600 void do_serial_work() { 4601 // Need to grab the lock to be allowed to modify the old region list. 4602 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 4603 _collection_set->iterate(&_cl); 4604 } 4605 4606 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) { 4607 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4608 4609 HeapRegion* r = g1h->region_at(region_idx); 4610 assert(!g1h->is_on_master_free_list(r), "sanity"); 4611 4612 Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths); 4613 4614 if (!is_young) { 4615 g1h->_hot_card_cache->reset_card_counts(r); 4616 } 4617 4618 if (!evacuation_failed) { 4619 r->rem_set()->clear_locked(); 4620 } 4621 } 4622 4623 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure { 4624 private: 4625 size_t _cur_idx; 4626 WorkItem* _work_items; 4627 public: 4628 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { } 4629 4630 virtual bool do_heap_region(HeapRegion* r) { 4631 _work_items[_cur_idx++] = WorkItem(r); 4632 return false; 4633 } 4634 }; 4635 4636 void prepare_work() { 4637 G1PrepareFreeCollectionSetClosure cl(_work_items); 4638 _collection_set->iterate(&cl); 4639 } 4640 4641 void complete_work() { 4642 _cl.complete_work(); 4643 4644 G1Policy* policy = G1CollectedHeap::heap()->g1_policy(); 4645 policy->record_max_rs_lengths(_rs_lengths); 4646 policy->cset_regions_freed(); 4647 } 4648 public: 4649 G1FreeCollectionSetTask(G1CollectionSet* collection_set, EvacuationInfo* evacuation_info, const size_t* surviving_young_words) : 4650 AbstractGangTask("G1 Free Collection Set"), 4651 _cl(evacuation_info, surviving_young_words), 4652 _collection_set(collection_set), 4653 _surviving_young_words(surviving_young_words), 4654 _serial_work_claim(0), 4655 _rs_lengths(0), 4656 _parallel_work_claim(0), 4657 _num_work_items(collection_set->region_length()), 4658 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) { 4659 prepare_work(); 4660 } 4661 4662 ~G1FreeCollectionSetTask() { 4663 complete_work(); 4664 FREE_C_HEAP_ARRAY(WorkItem, _work_items); 4665 } 4666 4667 // Chunk size for work distribution. The chosen value has been determined experimentally 4668 // to be a good tradeoff between overhead and achievable parallelism. 4669 static uint chunk_size() { return 32; } 4670 4671 virtual void work(uint worker_id) { 4672 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times(); 4673 4674 // Claim serial work. 4675 if (_serial_work_claim == 0) { 4676 jint value = Atomic::add(1, &_serial_work_claim) - 1; 4677 if (value == 0) { 4678 double serial_time = os::elapsedTime(); 4679 do_serial_work(); 4680 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0); 4681 } 4682 } 4683 4684 // Start parallel work. 4685 double young_time = 0.0; 4686 bool has_young_time = false; 4687 double non_young_time = 0.0; 4688 bool has_non_young_time = false; 4689 4690 while (true) { 4691 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim); 4692 size_t cur = end - chunk_size(); 4693 4694 if (cur >= _num_work_items) { 4695 break; 4696 } 4697 4698 double start_time = os::elapsedTime(); 4699 4700 end = MIN2(end, _num_work_items); 4701 4702 for (; cur < end; cur++) { 4703 bool is_young = _work_items[cur].is_young; 4704 4705 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed); 4706 4707 double end_time = os::elapsedTime(); 4708 double time_taken = end_time - start_time; 4709 if (is_young) { 4710 young_time += time_taken; 4711 has_young_time = true; 4712 } else { 4713 non_young_time += time_taken; 4714 has_non_young_time = true; 4715 } 4716 start_time = end_time; 4717 } 4718 } 4719 4720 if (has_young_time) { 4721 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time); 4722 } 4723 if (has_non_young_time) { 4724 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time); 4725 } 4726 } 4727 }; 4728 4729 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) { 4730 _eden.clear(); 4731 4732 double free_cset_start_time = os::elapsedTime(); 4733 4734 { 4735 uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U); 4736 uint const num_workers = MIN2(workers()->active_workers(), num_chunks); 4737 4738 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words); 4739 4740 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u", 4741 cl.name(), 4742 num_workers, 4743 _collection_set.region_length()); 4744 workers()->run_task(&cl, num_workers); 4745 } 4746 g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0); 4747 4748 collection_set->clear(); 4749 } 4750 4751 class G1FreeHumongousRegionClosure : public HeapRegionClosure { 4752 private: 4753 FreeRegionList* _free_region_list; 4754 HeapRegionSet* _proxy_set; 4755 uint _humongous_objects_reclaimed; 4756 uint _humongous_regions_reclaimed; 4757 size_t _freed_bytes; 4758 public: 4759 4760 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) : 4761 _free_region_list(free_region_list), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) { 4762 } 4763 4764 virtual bool do_heap_region(HeapRegion* r) { 4765 if (!r->is_starts_humongous()) { 4766 return false; 4767 } 4768 4769 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4770 4771 oop obj = (oop)r->bottom(); 4772 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap(); 4773 4774 // The following checks whether the humongous object is live are sufficient. 4775 // The main additional check (in addition to having a reference from the roots 4776 // or the young gen) is whether the humongous object has a remembered set entry. 4777 // 4778 // A humongous object cannot be live if there is no remembered set for it 4779 // because: 4780 // - there can be no references from within humongous starts regions referencing 4781 // the object because we never allocate other objects into them. 4782 // (I.e. there are no intra-region references that may be missed by the 4783 // remembered set) 4784 // - as soon there is a remembered set entry to the humongous starts region 4785 // (i.e. it has "escaped" to an old object) this remembered set entry will stay 4786 // until the end of a concurrent mark. 4787 // 4788 // It is not required to check whether the object has been found dead by marking 4789 // or not, in fact it would prevent reclamation within a concurrent cycle, as 4790 // all objects allocated during that time are considered live. 4791 // SATB marking is even more conservative than the remembered set. 4792 // So if at this point in the collection there is no remembered set entry, 4793 // nobody has a reference to it. 4794 // At the start of collection we flush all refinement logs, and remembered sets 4795 // are completely up-to-date wrt to references to the humongous object. 4796 // 4797 // Other implementation considerations: 4798 // - never consider object arrays at this time because they would pose 4799 // considerable effort for cleaning up the the remembered sets. This is 4800 // required because stale remembered sets might reference locations that 4801 // are currently allocated into. 4802 uint region_idx = r->hrm_index(); 4803 if (!g1h->is_humongous_reclaim_candidate(region_idx) || 4804 !r->rem_set()->is_empty()) { 4805 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", 4806 region_idx, 4807 (size_t)obj->size() * HeapWordSize, 4808 p2i(r->bottom()), 4809 r->rem_set()->occupied(), 4810 r->rem_set()->strong_code_roots_list_length(), 4811 next_bitmap->is_marked(r->bottom()), 4812 g1h->is_humongous_reclaim_candidate(region_idx), 4813 obj->is_typeArray() 4814 ); 4815 return false; 4816 } 4817 4818 guarantee(obj->is_typeArray(), 4819 "Only eagerly reclaiming type arrays is supported, but the object " 4820 PTR_FORMAT " is not.", p2i(r->bottom())); 4821 4822 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", 4823 region_idx, 4824 (size_t)obj->size() * HeapWordSize, 4825 p2i(r->bottom()), 4826 r->rem_set()->occupied(), 4827 r->rem_set()->strong_code_roots_list_length(), 4828 next_bitmap->is_marked(r->bottom()), 4829 g1h->is_humongous_reclaim_candidate(region_idx), 4830 obj->is_typeArray() 4831 ); 4832 4833 // Need to clear mark bit of the humongous object if already set. 4834 if (next_bitmap->is_marked(r->bottom())) { 4835 next_bitmap->clear(r->bottom()); 4836 } 4837 _humongous_objects_reclaimed++; 4838 do { 4839 HeapRegion* next = g1h->next_region_in_humongous(r); 4840 _freed_bytes += r->used(); 4841 r->set_containing_set(NULL); 4842 _humongous_regions_reclaimed++; 4843 g1h->free_humongous_region(r, _free_region_list, false /* skip_remset */ ); 4844 r = next; 4845 } while (r != NULL); 4846 4847 return false; 4848 } 4849 4850 uint humongous_objects_reclaimed() { 4851 return _humongous_objects_reclaimed; 4852 } 4853 4854 uint humongous_regions_reclaimed() { 4855 return _humongous_regions_reclaimed; 4856 } 4857 4858 size_t bytes_freed() const { 4859 return _freed_bytes; 4860 } 4861 }; 4862 4863 void G1CollectedHeap::eagerly_reclaim_humongous_regions() { 4864 assert_at_safepoint(true); 4865 4866 if (!G1EagerReclaimHumongousObjects || 4867 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) { 4868 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0); 4869 return; 4870 } 4871 4872 double start_time = os::elapsedTime(); 4873 4874 FreeRegionList local_cleanup_list("Local Humongous Cleanup List"); 4875 4876 G1FreeHumongousRegionClosure cl(&local_cleanup_list); 4877 heap_region_iterate(&cl); 4878 4879 remove_from_old_sets(0, cl.humongous_regions_reclaimed()); 4880 4881 G1HRPrinter* hrp = hr_printer(); 4882 if (hrp->is_active()) { 4883 FreeRegionListIterator iter(&local_cleanup_list); 4884 while (iter.more_available()) { 4885 HeapRegion* hr = iter.get_next(); 4886 hrp->cleanup(hr); 4887 } 4888 } 4889 4890 prepend_to_freelist(&local_cleanup_list); 4891 decrement_summary_bytes(cl.bytes_freed()); 4892 4893 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0, 4894 cl.humongous_objects_reclaimed()); 4895 } 4896 4897 class G1AbandonCollectionSetClosure : public HeapRegionClosure { 4898 public: 4899 virtual bool do_heap_region(HeapRegion* r) { 4900 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index()); 4901 G1CollectedHeap::heap()->clear_in_cset(r); 4902 r->set_young_index_in_cset(-1); 4903 return false; 4904 } 4905 }; 4906 4907 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) { 4908 G1AbandonCollectionSetClosure cl; 4909 collection_set->iterate(&cl); 4910 4911 collection_set->clear(); 4912 collection_set->stop_incremental_building(); 4913 } 4914 4915 void G1CollectedHeap::set_free_regions_coming() { 4916 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : setting free regions coming"); 4917 4918 assert(!free_regions_coming(), "pre-condition"); 4919 _free_regions_coming = true; 4920 } 4921 4922 void G1CollectedHeap::reset_free_regions_coming() { 4923 assert(free_regions_coming(), "pre-condition"); 4924 4925 { 4926 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 4927 _free_regions_coming = false; 4928 SecondaryFreeList_lock->notify_all(); 4929 } 4930 4931 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : reset free regions coming"); 4932 } 4933 4934 void G1CollectedHeap::wait_while_free_regions_coming() { 4935 // Most of the time we won't have to wait, so let's do a quick test 4936 // first before we take the lock. 4937 if (!free_regions_coming()) { 4938 return; 4939 } 4940 4941 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : waiting for free regions"); 4942 4943 { 4944 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 4945 while (free_regions_coming()) { 4946 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 4947 } 4948 } 4949 4950 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : done waiting for free regions"); 4951 } 4952 4953 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) { 4954 return _allocator->is_retained_old_region(hr); 4955 } 4956 4957 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 4958 _eden.add(hr); 4959 _g1_policy->set_region_eden(hr); 4960 } 4961 4962 #ifdef ASSERT 4963 4964 class NoYoungRegionsClosure: public HeapRegionClosure { 4965 private: 4966 bool _success; 4967 public: 4968 NoYoungRegionsClosure() : _success(true) { } 4969 bool do_heap_region(HeapRegion* r) { 4970 if (r->is_young()) { 4971 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young", 4972 p2i(r->bottom()), p2i(r->end())); 4973 _success = false; 4974 } 4975 return false; 4976 } 4977 bool success() { return _success; } 4978 }; 4979 4980 bool G1CollectedHeap::check_young_list_empty() { 4981 bool ret = (young_regions_count() == 0); 4982 4983 NoYoungRegionsClosure closure; 4984 heap_region_iterate(&closure); 4985 ret = ret && closure.success(); 4986 4987 return ret; 4988 } 4989 4990 #endif // ASSERT 4991 4992 class TearDownRegionSetsClosure : public HeapRegionClosure { 4993 private: 4994 HeapRegionSet *_old_set; 4995 4996 public: 4997 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { } 4998 4999 bool do_heap_region(HeapRegion* r) { 5000 if (r->is_old()) { 5001 _old_set->remove(r); 5002 } else if(r->is_young()) { 5003 r->uninstall_surv_rate_group(); 5004 } else { 5005 // We ignore free regions, we'll empty the free list afterwards. 5006 // We ignore humongous regions, we're not tearing down the 5007 // humongous regions set. 5008 assert(r->is_free() || r->is_humongous(), 5009 "it cannot be another type"); 5010 } 5011 return false; 5012 } 5013 5014 ~TearDownRegionSetsClosure() { 5015 assert(_old_set->is_empty(), "post-condition"); 5016 } 5017 }; 5018 5019 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) { 5020 assert_at_safepoint(true /* should_be_vm_thread */); 5021 5022 if (!free_list_only) { 5023 TearDownRegionSetsClosure cl(&_old_set); 5024 heap_region_iterate(&cl); 5025 5026 // Note that emptying the _young_list is postponed and instead done as 5027 // the first step when rebuilding the regions sets again. The reason for 5028 // this is that during a full GC string deduplication needs to know if 5029 // a collected region was young or old when the full GC was initiated. 5030 } 5031 _hrm.remove_all_free_regions(); 5032 } 5033 5034 void G1CollectedHeap::increase_used(size_t bytes) { 5035 _summary_bytes_used += bytes; 5036 } 5037 5038 void G1CollectedHeap::decrease_used(size_t bytes) { 5039 assert(_summary_bytes_used >= bytes, 5040 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT, 5041 _summary_bytes_used, bytes); 5042 _summary_bytes_used -= bytes; 5043 } 5044 5045 void G1CollectedHeap::set_used(size_t bytes) { 5046 _summary_bytes_used = bytes; 5047 } 5048 5049 class RebuildRegionSetsClosure : public HeapRegionClosure { 5050 private: 5051 bool _free_list_only; 5052 HeapRegionSet* _old_set; 5053 HeapRegionManager* _hrm; 5054 size_t _total_used; 5055 5056 public: 5057 RebuildRegionSetsClosure(bool free_list_only, 5058 HeapRegionSet* old_set, HeapRegionManager* hrm) : 5059 _free_list_only(free_list_only), 5060 _old_set(old_set), _hrm(hrm), _total_used(0) { 5061 assert(_hrm->num_free_regions() == 0, "pre-condition"); 5062 if (!free_list_only) { 5063 assert(_old_set->is_empty(), "pre-condition"); 5064 } 5065 } 5066 5067 bool do_heap_region(HeapRegion* r) { 5068 if (r->is_empty()) { 5069 // Add free regions to the free list 5070 r->set_free(); 5071 r->set_allocation_context(AllocationContext::system()); 5072 _hrm->insert_into_free_list(r); 5073 } else if (!_free_list_only) { 5074 5075 if (r->is_humongous()) { 5076 // We ignore humongous regions. We left the humongous set unchanged. 5077 } else { 5078 assert(r->is_young() || r->is_free() || r->is_old(), "invariant"); 5079 // We now move all (non-humongous, non-old) regions to old gen, and register them as such. 5080 r->move_to_old(); 5081 _old_set->add(r); 5082 } 5083 _total_used += r->used(); 5084 } 5085 5086 return false; 5087 } 5088 5089 size_t total_used() { 5090 return _total_used; 5091 } 5092 }; 5093 5094 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { 5095 assert_at_safepoint(true /* should_be_vm_thread */); 5096 5097 if (!free_list_only) { 5098 _eden.clear(); 5099 _survivor.clear(); 5100 } 5101 5102 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm); 5103 heap_region_iterate(&cl); 5104 5105 if (!free_list_only) { 5106 set_used(cl.total_used()); 5107 if (_archive_allocator != NULL) { 5108 _archive_allocator->clear_used(); 5109 } 5110 } 5111 assert(used_unlocked() == recalculate_used(), 5112 "inconsistent used_unlocked(), " 5113 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT, 5114 used_unlocked(), recalculate_used()); 5115 } 5116 5117 bool G1CollectedHeap::is_in_closed_subset(const void* p) const { 5118 HeapRegion* hr = heap_region_containing(p); 5119 return hr->is_in(p); 5120 } 5121 5122 // Methods for the mutator alloc region 5123 5124 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 5125 bool force) { 5126 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 5127 bool should_allocate = g1_policy()->should_allocate_mutator_region(); 5128 if (force || should_allocate) { 5129 HeapRegion* new_alloc_region = new_region(word_size, 5130 false /* is_old */, 5131 false /* do_expand */); 5132 if (new_alloc_region != NULL) { 5133 set_region_short_lived_locked(new_alloc_region); 5134 _hr_printer.alloc(new_alloc_region, !should_allocate); 5135 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region); 5136 return new_alloc_region; 5137 } 5138 } 5139 return NULL; 5140 } 5141 5142 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 5143 size_t allocated_bytes) { 5144 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 5145 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden"); 5146 5147 collection_set()->add_eden_region(alloc_region); 5148 increase_used(allocated_bytes); 5149 _hr_printer.retire(alloc_region); 5150 // We update the eden sizes here, when the region is retired, 5151 // instead of when it's allocated, since this is the point that its 5152 // used space has been recored in _summary_bytes_used. 5153 g1mm()->update_eden_size(); 5154 } 5155 5156 // Methods for the GC alloc regions 5157 5158 bool G1CollectedHeap::has_more_regions(InCSetState dest) { 5159 if (dest.is_old()) { 5160 return true; 5161 } else { 5162 return survivor_regions_count() < g1_policy()->max_survivor_regions(); 5163 } 5164 } 5165 5166 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) { 5167 assert(FreeList_lock->owned_by_self(), "pre-condition"); 5168 5169 if (!has_more_regions(dest)) { 5170 return NULL; 5171 } 5172 5173 const bool is_survivor = dest.is_young(); 5174 5175 HeapRegion* new_alloc_region = new_region(word_size, 5176 !is_survivor, 5177 true /* do_expand */); 5178 if (new_alloc_region != NULL) { 5179 // We really only need to do this for old regions given that we 5180 // should never scan survivors. But it doesn't hurt to do it 5181 // for survivors too. 5182 new_alloc_region->record_timestamp(); 5183 if (is_survivor) { 5184 new_alloc_region->set_survivor(); 5185 _survivor.add(new_alloc_region); 5186 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region); 5187 } else { 5188 new_alloc_region->set_old(); 5189 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region); 5190 } 5191 _hr_printer.alloc(new_alloc_region); 5192 bool during_im = collector_state()->during_initial_mark_pause(); 5193 new_alloc_region->note_start_of_copying(during_im); 5194 return new_alloc_region; 5195 } 5196 return NULL; 5197 } 5198 5199 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 5200 size_t allocated_bytes, 5201 InCSetState dest) { 5202 bool during_im = collector_state()->during_initial_mark_pause(); 5203 alloc_region->note_end_of_copying(during_im); 5204 g1_policy()->record_bytes_copied_during_gc(allocated_bytes); 5205 if (dest.is_old()) { 5206 _old_set.add(alloc_region); 5207 } 5208 _hr_printer.retire(alloc_region); 5209 } 5210 5211 HeapRegion* G1CollectedHeap::alloc_highest_free_region() { 5212 bool expanded = false; 5213 uint index = _hrm.find_highest_free(&expanded); 5214 5215 if (index != G1_NO_HRM_INDEX) { 5216 if (expanded) { 5217 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B", 5218 HeapRegion::GrainWords * HeapWordSize); 5219 } 5220 _hrm.allocate_free_regions_starting_at(index, 1); 5221 return region_at(index); 5222 } 5223 return NULL; 5224 } 5225 5226 // Optimized nmethod scanning 5227 5228 class RegisterNMethodOopClosure: public OopClosure { 5229 G1CollectedHeap* _g1h; 5230 nmethod* _nm; 5231 5232 template <class T> void do_oop_work(T* p) { 5233 T heap_oop = oopDesc::load_heap_oop(p); 5234 if (!oopDesc::is_null(heap_oop)) { 5235 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 5236 HeapRegion* hr = _g1h->heap_region_containing(obj); 5237 assert(!hr->is_continues_humongous(), 5238 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 5239 " starting at " HR_FORMAT, 5240 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 5241 5242 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries. 5243 hr->add_strong_code_root_locked(_nm); 5244 } 5245 } 5246 5247 public: 5248 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 5249 _g1h(g1h), _nm(nm) {} 5250 5251 void do_oop(oop* p) { do_oop_work(p); } 5252 void do_oop(narrowOop* p) { do_oop_work(p); } 5253 }; 5254 5255 class UnregisterNMethodOopClosure: public OopClosure { 5256 G1CollectedHeap* _g1h; 5257 nmethod* _nm; 5258 5259 template <class T> void do_oop_work(T* p) { 5260 T heap_oop = oopDesc::load_heap_oop(p); 5261 if (!oopDesc::is_null(heap_oop)) { 5262 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 5263 HeapRegion* hr = _g1h->heap_region_containing(obj); 5264 assert(!hr->is_continues_humongous(), 5265 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 5266 " starting at " HR_FORMAT, 5267 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 5268 5269 hr->remove_strong_code_root(_nm); 5270 } 5271 } 5272 5273 public: 5274 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 5275 _g1h(g1h), _nm(nm) {} 5276 5277 void do_oop(oop* p) { do_oop_work(p); } 5278 void do_oop(narrowOop* p) { do_oop_work(p); } 5279 }; 5280 5281 // Returns true if the reference points to an object that 5282 // can move in an incremental collection. 5283 bool G1CollectedHeap::is_scavengable(oop obj) { 5284 HeapRegion* hr = heap_region_containing(obj); 5285 return !hr->is_pinned(); 5286 } 5287 5288 void G1CollectedHeap::register_nmethod(nmethod* nm) { 5289 guarantee(nm != NULL, "sanity"); 5290 RegisterNMethodOopClosure reg_cl(this, nm); 5291 nm->oops_do(®_cl); 5292 } 5293 5294 void G1CollectedHeap::unregister_nmethod(nmethod* nm) { 5295 guarantee(nm != NULL, "sanity"); 5296 UnregisterNMethodOopClosure reg_cl(this, nm); 5297 nm->oops_do(®_cl, true); 5298 } 5299 5300 void G1CollectedHeap::purge_code_root_memory() { 5301 double purge_start = os::elapsedTime(); 5302 G1CodeRootSet::purge(); 5303 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0; 5304 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms); 5305 } 5306 5307 class RebuildStrongCodeRootClosure: public CodeBlobClosure { 5308 G1CollectedHeap* _g1h; 5309 5310 public: 5311 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) : 5312 _g1h(g1h) {} 5313 5314 void do_code_blob(CodeBlob* cb) { 5315 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL; 5316 if (nm == NULL) { 5317 return; 5318 } 5319 5320 if (ScavengeRootsInCode) { 5321 _g1h->register_nmethod(nm); 5322 } 5323 } 5324 }; 5325 5326 void G1CollectedHeap::rebuild_strong_code_roots() { 5327 RebuildStrongCodeRootClosure blob_cl(this); 5328 CodeCache::blobs_do(&blob_cl); 5329 } 5330 5331 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() { 5332 GrowableArray<GCMemoryManager*> memory_managers(2); 5333 memory_managers.append(&_memory_manager); 5334 memory_managers.append(&_full_gc_memory_manager); 5335 return memory_managers; 5336 } 5337 5338 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() { 5339 GrowableArray<MemoryPool*> memory_pools(3); 5340 memory_pools.append(_eden_pool); 5341 memory_pools.append(_survivor_pool); 5342 memory_pools.append(_old_pool); 5343 return memory_pools; 5344 }