1 /* 2 * Copyright (c) 2001, 2017, 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/concurrentG1Refine.hpp" 33 #include "gc/g1/concurrentG1RefineThread.hpp" 34 #include "gc/g1/concurrentMarkThread.inline.hpp" 35 #include "gc/g1/g1Allocator.inline.hpp" 36 #include "gc/g1/g1CollectedHeap.inline.hpp" 37 #include "gc/g1/g1CollectionSet.hpp" 38 #include "gc/g1/g1CollectorPolicy.hpp" 39 #include "gc/g1/g1CollectorState.hpp" 40 #include "gc/g1/g1EvacStats.inline.hpp" 41 #include "gc/g1/g1GCPhaseTimes.hpp" 42 #include "gc/g1/g1HeapSizingPolicy.hpp" 43 #include "gc/g1/g1HeapTransition.hpp" 44 #include "gc/g1/g1HeapVerifier.hpp" 45 #include "gc/g1/g1HotCardCache.hpp" 46 #include "gc/g1/g1MarkSweep.hpp" 47 #include "gc/g1/g1OopClosures.inline.hpp" 48 #include "gc/g1/g1ParScanThreadState.inline.hpp" 49 #include "gc/g1/g1Policy.hpp" 50 #include "gc/g1/g1RegionToSpaceMapper.hpp" 51 #include "gc/g1/g1RemSet.inline.hpp" 52 #include "gc/g1/g1RootClosures.hpp" 53 #include "gc/g1/g1RootProcessor.hpp" 54 #include "gc/g1/g1StringDedup.hpp" 55 #include "gc/g1/g1YCTypes.hpp" 56 #include "gc/g1/heapRegion.inline.hpp" 57 #include "gc/g1/heapRegionRemSet.hpp" 58 #include "gc/g1/heapRegionSet.inline.hpp" 59 #include "gc/g1/suspendibleThreadSet.hpp" 60 #include "gc/g1/vm_operations_g1.hpp" 61 #include "gc/shared/gcHeapSummary.hpp" 62 #include "gc/shared/gcId.hpp" 63 #include "gc/shared/gcLocker.inline.hpp" 64 #include "gc/shared/gcTimer.hpp" 65 #include "gc/shared/gcTrace.hpp" 66 #include "gc/shared/gcTraceTime.inline.hpp" 67 #include "gc/shared/generationSpec.hpp" 68 #include "gc/shared/isGCActiveMark.hpp" 69 #include "gc/shared/preservedMarks.inline.hpp" 70 #include "gc/shared/referenceProcessor.inline.hpp" 71 #include "gc/shared/taskqueue.inline.hpp" 72 #include "logging/log.hpp" 73 #include "memory/allocation.hpp" 74 #include "memory/iterator.hpp" 75 #include "memory/resourceArea.hpp" 76 #include "oops/oop.inline.hpp" 77 #include "runtime/atomic.hpp" 78 #include "runtime/init.hpp" 79 #include "runtime/orderAccess.inline.hpp" 80 #include "runtime/vmThread.hpp" 81 #include "utilities/globalDefinitions.hpp" 82 #include "utilities/stack.inline.hpp" 83 84 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0; 85 86 // INVARIANTS/NOTES 87 // 88 // All allocation activity covered by the G1CollectedHeap interface is 89 // serialized by acquiring the HeapLock. This happens in mem_allocate 90 // and allocate_new_tlab, which are the "entry" points to the 91 // allocation code from the rest of the JVM. (Note that this does not 92 // apply to TLAB allocation, which is not part of this interface: it 93 // is done by clients of this interface.) 94 95 // Local to this file. 96 97 class RefineCardTableEntryClosure: public CardTableEntryClosure { 98 bool _concurrent; 99 public: 100 RefineCardTableEntryClosure() : _concurrent(true) { } 101 102 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 103 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, NULL); 104 // This path is executed by the concurrent refine or mutator threads, 105 // concurrently, and so we do not care if card_ptr contains references 106 // that point into the collection set. 107 assert(!oops_into_cset, "should be"); 108 109 if (_concurrent && SuspendibleThreadSet::should_yield()) { 110 // Caller will actually yield. 111 return false; 112 } 113 // Otherwise, we finished successfully; return true. 114 return true; 115 } 116 117 void set_concurrent(bool b) { _concurrent = b; } 118 }; 119 120 121 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure { 122 private: 123 size_t _num_dirtied; 124 G1CollectedHeap* _g1h; 125 G1SATBCardTableLoggingModRefBS* _g1_bs; 126 127 HeapRegion* region_for_card(jbyte* card_ptr) const { 128 return _g1h->heap_region_containing(_g1_bs->addr_for(card_ptr)); 129 } 130 131 bool will_become_free(HeapRegion* hr) const { 132 // A region will be freed by free_collection_set if the region is in the 133 // collection set and has not had an evacuation failure. 134 return _g1h->is_in_cset(hr) && !hr->evacuation_failed(); 135 } 136 137 public: 138 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(), 139 _num_dirtied(0), _g1h(g1h), _g1_bs(g1h->g1_barrier_set()) { } 140 141 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 142 HeapRegion* hr = region_for_card(card_ptr); 143 144 // Should only dirty cards in regions that won't be freed. 145 if (!will_become_free(hr)) { 146 *card_ptr = CardTableModRefBS::dirty_card_val(); 147 _num_dirtied++; 148 } 149 150 return true; 151 } 152 153 size_t num_dirtied() const { return _num_dirtied; } 154 }; 155 156 157 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) { 158 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions); 159 } 160 161 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) { 162 // The from card cache is not the memory that is actually committed. So we cannot 163 // take advantage of the zero_filled parameter. 164 reset_from_card_cache(start_idx, num_regions); 165 } 166 167 // Returns true if the reference points to an object that 168 // can move in an incremental collection. 169 bool G1CollectedHeap::is_scavengable(const void* p) { 170 HeapRegion* hr = heap_region_containing(p); 171 return !hr->is_pinned(); 172 } 173 174 // Private methods. 175 176 HeapRegion* 177 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) { 178 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 179 while (!_secondary_free_list.is_empty() || free_regions_coming()) { 180 if (!_secondary_free_list.is_empty()) { 181 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : " 182 "secondary_free_list has %u entries", 183 _secondary_free_list.length()); 184 // It looks as if there are free regions available on the 185 // secondary_free_list. Let's move them to the free_list and try 186 // again to allocate from it. 187 append_secondary_free_list(); 188 189 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not " 190 "empty we should have moved at least one entry to the free_list"); 191 HeapRegion* res = _hrm.allocate_free_region(is_old); 192 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : " 193 "allocated " HR_FORMAT " from secondary_free_list", 194 HR_FORMAT_PARAMS(res)); 195 return res; 196 } 197 198 // Wait here until we get notified either when (a) there are no 199 // more free regions coming or (b) some regions have been moved on 200 // the secondary_free_list. 201 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 202 } 203 204 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : " 205 "could not allocate from secondary_free_list"); 206 return NULL; 207 } 208 209 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) { 210 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords, 211 "the only time we use this to allocate a humongous region is " 212 "when we are allocating a single humongous region"); 213 214 HeapRegion* res; 215 if (G1StressConcRegionFreeing) { 216 if (!_secondary_free_list.is_empty()) { 217 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : " 218 "forced to look at the secondary_free_list"); 219 res = new_region_try_secondary_free_list(is_old); 220 if (res != NULL) { 221 return res; 222 } 223 } 224 } 225 226 res = _hrm.allocate_free_region(is_old); 227 228 if (res == NULL) { 229 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : " 230 "res == NULL, trying the secondary_free_list"); 231 res = new_region_try_secondary_free_list(is_old); 232 } 233 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) { 234 // Currently, only attempts to allocate GC alloc regions set 235 // do_expand to true. So, we should only reach here during a 236 // safepoint. If this assumption changes we might have to 237 // reconsider the use of _expand_heap_after_alloc_failure. 238 assert(SafepointSynchronize::is_at_safepoint(), "invariant"); 239 240 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B", 241 word_size * HeapWordSize); 242 243 if (expand(word_size * HeapWordSize)) { 244 // Given that expand() succeeded in expanding the heap, and we 245 // always expand the heap by an amount aligned to the heap 246 // region size, the free list should in theory not be empty. 247 // In either case allocate_free_region() will check for NULL. 248 res = _hrm.allocate_free_region(is_old); 249 } else { 250 _expand_heap_after_alloc_failure = false; 251 } 252 } 253 return res; 254 } 255 256 HeapWord* 257 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first, 258 uint num_regions, 259 size_t word_size, 260 AllocationContext_t context) { 261 assert(first != G1_NO_HRM_INDEX, "pre-condition"); 262 assert(is_humongous(word_size), "word_size should be humongous"); 263 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition"); 264 265 // Index of last region in the series. 266 uint last = first + num_regions - 1; 267 268 // We need to initialize the region(s) we just discovered. This is 269 // a bit tricky given that it can happen concurrently with 270 // refinement threads refining cards on these regions and 271 // potentially wanting to refine the BOT as they are scanning 272 // those cards (this can happen shortly after a cleanup; see CR 273 // 6991377). So we have to set up the region(s) carefully and in 274 // a specific order. 275 276 // The word size sum of all the regions we will allocate. 277 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords; 278 assert(word_size <= word_size_sum, "sanity"); 279 280 // This will be the "starts humongous" region. 281 HeapRegion* first_hr = region_at(first); 282 // The header of the new object will be placed at the bottom of 283 // the first region. 284 HeapWord* new_obj = first_hr->bottom(); 285 // This will be the new top of the new object. 286 HeapWord* obj_top = new_obj + word_size; 287 288 // First, we need to zero the header of the space that we will be 289 // allocating. When we update top further down, some refinement 290 // threads might try to scan the region. By zeroing the header we 291 // ensure that any thread that will try to scan the region will 292 // come across the zero klass word and bail out. 293 // 294 // NOTE: It would not have been correct to have used 295 // CollectedHeap::fill_with_object() and make the space look like 296 // an int array. The thread that is doing the allocation will 297 // later update the object header to a potentially different array 298 // type and, for a very short period of time, the klass and length 299 // fields will be inconsistent. This could cause a refinement 300 // thread to calculate the object size incorrectly. 301 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0); 302 303 // Next, pad out the unused tail of the last region with filler 304 // objects, for improved usage accounting. 305 // How many words we use for filler objects. 306 size_t word_fill_size = word_size_sum - word_size; 307 308 // How many words memory we "waste" which cannot hold a filler object. 309 size_t words_not_fillable = 0; 310 311 if (word_fill_size >= min_fill_size()) { 312 fill_with_objects(obj_top, word_fill_size); 313 } else if (word_fill_size > 0) { 314 // We have space to fill, but we cannot fit an object there. 315 words_not_fillable = word_fill_size; 316 word_fill_size = 0; 317 } 318 319 // We will set up the first region as "starts humongous". This 320 // will also update the BOT covering all the regions to reflect 321 // that there is a single object that starts at the bottom of the 322 // first region. 323 first_hr->set_starts_humongous(obj_top, word_fill_size); 324 first_hr->set_allocation_context(context); 325 // Then, if there are any, we will set up the "continues 326 // humongous" regions. 327 HeapRegion* hr = NULL; 328 for (uint i = first + 1; i <= last; ++i) { 329 hr = region_at(i); 330 hr->set_continues_humongous(first_hr); 331 hr->set_allocation_context(context); 332 } 333 334 // Up to this point no concurrent thread would have been able to 335 // do any scanning on any region in this series. All the top 336 // fields still point to bottom, so the intersection between 337 // [bottom,top] and [card_start,card_end] will be empty. Before we 338 // update the top fields, we'll do a storestore to make sure that 339 // no thread sees the update to top before the zeroing of the 340 // object header and the BOT initialization. 341 OrderAccess::storestore(); 342 343 // Now, we will update the top fields of the "continues humongous" 344 // regions except the last one. 345 for (uint i = first; i < last; ++i) { 346 hr = region_at(i); 347 hr->set_top(hr->end()); 348 } 349 350 hr = region_at(last); 351 // If we cannot fit a filler object, we must set top to the end 352 // of the humongous object, otherwise we cannot iterate the heap 353 // and the BOT will not be complete. 354 hr->set_top(hr->end() - words_not_fillable); 355 356 assert(hr->bottom() < obj_top && obj_top <= hr->end(), 357 "obj_top should be in last region"); 358 359 _verifier->check_bitmaps("Humongous Region Allocation", first_hr); 360 361 assert(words_not_fillable == 0 || 362 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(), 363 "Miscalculation in humongous allocation"); 364 365 increase_used((word_size_sum - words_not_fillable) * HeapWordSize); 366 367 for (uint i = first; i <= last; ++i) { 368 hr = region_at(i); 369 _humongous_set.add(hr); 370 _hr_printer.alloc(hr); 371 } 372 373 return new_obj; 374 } 375 376 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) { 377 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size); 378 return align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords; 379 } 380 381 // If could fit into free regions w/o expansion, try. 382 // Otherwise, if can expand, do so. 383 // Otherwise, if using ex regions might help, try with ex given back. 384 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) { 385 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 386 387 _verifier->verify_region_sets_optional(); 388 389 uint first = G1_NO_HRM_INDEX; 390 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size); 391 392 if (obj_regions == 1) { 393 // Only one region to allocate, try to use a fast path by directly allocating 394 // from the free lists. Do not try to expand here, we will potentially do that 395 // later. 396 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */); 397 if (hr != NULL) { 398 first = hr->hrm_index(); 399 } 400 } else { 401 // We can't allocate humongous regions spanning more than one region while 402 // cleanupComplete() is running, since some of the regions we find to be 403 // empty might not yet be added to the free list. It is not straightforward 404 // to know in which list they are on so that we can remove them. We only 405 // need to do this if we need to allocate more than one region to satisfy the 406 // current humongous allocation request. If we are only allocating one region 407 // we use the one-region region allocation code (see above), that already 408 // potentially waits for regions from the secondary free list. 409 wait_while_free_regions_coming(); 410 append_secondary_free_list_if_not_empty_with_lock(); 411 412 // Policy: Try only empty regions (i.e. already committed first). Maybe we 413 // are lucky enough to find some. 414 first = _hrm.find_contiguous_only_empty(obj_regions); 415 if (first != G1_NO_HRM_INDEX) { 416 _hrm.allocate_free_regions_starting_at(first, obj_regions); 417 } 418 } 419 420 if (first == G1_NO_HRM_INDEX) { 421 // Policy: We could not find enough regions for the humongous object in the 422 // free list. Look through the heap to find a mix of free and uncommitted regions. 423 // If so, try expansion. 424 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions); 425 if (first != G1_NO_HRM_INDEX) { 426 // We found something. Make sure these regions are committed, i.e. expand 427 // the heap. Alternatively we could do a defragmentation GC. 428 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B", 429 word_size * HeapWordSize); 430 431 _hrm.expand_at(first, obj_regions, workers()); 432 g1_policy()->record_new_heap_size(num_regions()); 433 434 #ifdef ASSERT 435 for (uint i = first; i < first + obj_regions; ++i) { 436 HeapRegion* hr = region_at(i); 437 assert(hr->is_free(), "sanity"); 438 assert(hr->is_empty(), "sanity"); 439 assert(is_on_master_free_list(hr), "sanity"); 440 } 441 #endif 442 _hrm.allocate_free_regions_starting_at(first, obj_regions); 443 } else { 444 // Policy: Potentially trigger a defragmentation GC. 445 } 446 } 447 448 HeapWord* result = NULL; 449 if (first != G1_NO_HRM_INDEX) { 450 result = humongous_obj_allocate_initialize_regions(first, obj_regions, 451 word_size, context); 452 assert(result != NULL, "it should always return a valid result"); 453 454 // A successful humongous object allocation changes the used space 455 // information of the old generation so we need to recalculate the 456 // sizes and update the jstat counters here. 457 g1mm()->update_sizes(); 458 } 459 460 _verifier->verify_region_sets_optional(); 461 462 return result; 463 } 464 465 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) { 466 assert_heap_not_locked_and_not_at_safepoint(); 467 assert(!is_humongous(word_size), "we do not allow humongous TLABs"); 468 469 uint dummy_gc_count_before; 470 uint dummy_gclocker_retry_count = 0; 471 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count); 472 } 473 474 HeapWord* 475 G1CollectedHeap::mem_allocate(size_t word_size, 476 bool* gc_overhead_limit_was_exceeded) { 477 assert_heap_not_locked_and_not_at_safepoint(); 478 479 // Loop until the allocation is satisfied, or unsatisfied after GC. 480 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 481 uint gc_count_before; 482 483 HeapWord* result = NULL; 484 if (!is_humongous(word_size)) { 485 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count); 486 } else { 487 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count); 488 } 489 if (result != NULL) { 490 return result; 491 } 492 493 // Create the garbage collection operation... 494 VM_G1CollectForAllocation op(gc_count_before, word_size); 495 op.set_allocation_context(AllocationContext::current()); 496 497 // ...and get the VM thread to execute it. 498 VMThread::execute(&op); 499 500 if (op.prologue_succeeded() && op.pause_succeeded()) { 501 // If the operation was successful we'll return the result even 502 // if it is NULL. If the allocation attempt failed immediately 503 // after a Full GC, it's unlikely we'll be able to allocate now. 504 HeapWord* result = op.result(); 505 if (result != NULL && !is_humongous(word_size)) { 506 // Allocations that take place on VM operations do not do any 507 // card dirtying and we have to do it here. We only have to do 508 // this for non-humongous allocations, though. 509 dirty_young_block(result, word_size); 510 } 511 return result; 512 } else { 513 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 514 return NULL; 515 } 516 assert(op.result() == NULL, 517 "the result should be NULL if the VM op did not succeed"); 518 } 519 520 // Give a warning if we seem to be looping forever. 521 if ((QueuedAllocationWarningCount > 0) && 522 (try_count % QueuedAllocationWarningCount == 0)) { 523 log_warning(gc)("G1CollectedHeap::mem_allocate retries %d times", try_count); 524 } 525 } 526 527 ShouldNotReachHere(); 528 return NULL; 529 } 530 531 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size, 532 AllocationContext_t context, 533 uint* gc_count_before_ret, 534 uint* gclocker_retry_count_ret) { 535 // Make sure you read the note in attempt_allocation_humongous(). 536 537 assert_heap_not_locked_and_not_at_safepoint(); 538 assert(!is_humongous(word_size), "attempt_allocation_slow() should not " 539 "be called for humongous allocation requests"); 540 541 // We should only get here after the first-level allocation attempt 542 // (attempt_allocation()) failed to allocate. 543 544 // We will loop until a) we manage to successfully perform the 545 // allocation or b) we successfully schedule a collection which 546 // fails to perform the allocation. b) is the only case when we'll 547 // return NULL. 548 HeapWord* result = NULL; 549 for (int try_count = 1; /* we'll return */; try_count += 1) { 550 bool should_try_gc; 551 uint gc_count_before; 552 553 { 554 MutexLockerEx x(Heap_lock); 555 result = _allocator->attempt_allocation_locked(word_size, context); 556 if (result != NULL) { 557 return result; 558 } 559 560 if (GCLocker::is_active_and_needs_gc()) { 561 if (g1_policy()->can_expand_young_list()) { 562 // No need for an ergo verbose message here, 563 // can_expand_young_list() does this when it returns true. 564 result = _allocator->attempt_allocation_force(word_size, context); 565 if (result != NULL) { 566 return result; 567 } 568 } 569 should_try_gc = false; 570 } else { 571 // The GCLocker may not be active but the GCLocker initiated 572 // GC may not yet have been performed (GCLocker::needs_gc() 573 // returns true). In this case we do not try this GC and 574 // wait until the GCLocker initiated GC is performed, and 575 // then retry the allocation. 576 if (GCLocker::needs_gc()) { 577 should_try_gc = false; 578 } else { 579 // Read the GC count while still holding the Heap_lock. 580 gc_count_before = total_collections(); 581 should_try_gc = true; 582 } 583 } 584 } 585 586 if (should_try_gc) { 587 bool succeeded; 588 result = do_collection_pause(word_size, gc_count_before, &succeeded, 589 GCCause::_g1_inc_collection_pause); 590 if (result != NULL) { 591 assert(succeeded, "only way to get back a non-NULL result"); 592 return result; 593 } 594 595 if (succeeded) { 596 // If we get here we successfully scheduled a collection which 597 // failed to allocate. No point in trying to allocate 598 // further. We'll just return NULL. 599 MutexLockerEx x(Heap_lock); 600 *gc_count_before_ret = total_collections(); 601 return NULL; 602 } 603 } else { 604 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { 605 MutexLockerEx x(Heap_lock); 606 *gc_count_before_ret = total_collections(); 607 return NULL; 608 } 609 // The GCLocker is either active or the GCLocker initiated 610 // GC has not yet been performed. Stall until it is and 611 // then retry the allocation. 612 GCLocker::stall_until_clear(); 613 (*gclocker_retry_count_ret) += 1; 614 } 615 616 // We can reach here if we were unsuccessful in scheduling a 617 // collection (because another thread beat us to it) or if we were 618 // stalled due to the GC locker. In either can we should retry the 619 // allocation attempt in case another thread successfully 620 // performed a collection and reclaimed enough space. We do the 621 // first attempt (without holding the Heap_lock) here and the 622 // follow-on attempt will be at the start of the next loop 623 // iteration (after taking the Heap_lock). 624 result = _allocator->attempt_allocation(word_size, context); 625 if (result != NULL) { 626 return result; 627 } 628 629 // Give a warning if we seem to be looping forever. 630 if ((QueuedAllocationWarningCount > 0) && 631 (try_count % QueuedAllocationWarningCount == 0)) { 632 log_warning(gc)("G1CollectedHeap::attempt_allocation_slow() " 633 "retries %d times", try_count); 634 } 635 } 636 637 ShouldNotReachHere(); 638 return NULL; 639 } 640 641 void G1CollectedHeap::begin_archive_alloc_range() { 642 assert_at_safepoint(true /* should_be_vm_thread */); 643 if (_archive_allocator == NULL) { 644 _archive_allocator = G1ArchiveAllocator::create_allocator(this); 645 } 646 } 647 648 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) { 649 // Allocations in archive regions cannot be of a size that would be considered 650 // humongous even for a minimum-sized region, because G1 region sizes/boundaries 651 // may be different at archive-restore time. 652 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words()); 653 } 654 655 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) { 656 assert_at_safepoint(true /* should_be_vm_thread */); 657 assert(_archive_allocator != NULL, "_archive_allocator not initialized"); 658 if (is_archive_alloc_too_large(word_size)) { 659 return NULL; 660 } 661 return _archive_allocator->archive_mem_allocate(word_size); 662 } 663 664 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges, 665 size_t end_alignment_in_bytes) { 666 assert_at_safepoint(true /* should_be_vm_thread */); 667 assert(_archive_allocator != NULL, "_archive_allocator not initialized"); 668 669 // Call complete_archive to do the real work, filling in the MemRegion 670 // array with the archive regions. 671 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes); 672 delete _archive_allocator; 673 _archive_allocator = NULL; 674 } 675 676 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) { 677 assert(ranges != NULL, "MemRegion array NULL"); 678 assert(count != 0, "No MemRegions provided"); 679 MemRegion reserved = _hrm.reserved(); 680 for (size_t i = 0; i < count; i++) { 681 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) { 682 return false; 683 } 684 } 685 return true; 686 } 687 688 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) { 689 assert(!is_init_completed(), "Expect to be called at JVM init time"); 690 assert(ranges != NULL, "MemRegion array NULL"); 691 assert(count != 0, "No MemRegions provided"); 692 MutexLockerEx x(Heap_lock); 693 694 MemRegion reserved = _hrm.reserved(); 695 HeapWord* prev_last_addr = NULL; 696 HeapRegion* prev_last_region = NULL; 697 698 // Temporarily disable pretouching of heap pages. This interface is used 699 // when mmap'ing archived heap data in, so pre-touching is wasted. 700 FlagSetting fs(AlwaysPreTouch, false); 701 702 // Enable archive object checking in G1MarkSweep. We have to let it know 703 // about each archive range, so that objects in those ranges aren't marked. 704 G1MarkSweep::enable_archive_object_check(); 705 706 // For each specified MemRegion range, allocate the corresponding G1 707 // regions and mark them as archive regions. We expect the ranges in 708 // ascending starting address order, without overlap. 709 for (size_t i = 0; i < count; i++) { 710 MemRegion curr_range = ranges[i]; 711 HeapWord* start_address = curr_range.start(); 712 size_t word_size = curr_range.word_size(); 713 HeapWord* last_address = curr_range.last(); 714 size_t commits = 0; 715 716 guarantee(reserved.contains(start_address) && reserved.contains(last_address), 717 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 718 p2i(start_address), p2i(last_address)); 719 guarantee(start_address > prev_last_addr, 720 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 721 p2i(start_address), p2i(prev_last_addr)); 722 prev_last_addr = last_address; 723 724 // Check for ranges that start in the same G1 region in which the previous 725 // range ended, and adjust the start address so we don't try to allocate 726 // the same region again. If the current range is entirely within that 727 // region, skip it, just adjusting the recorded top. 728 HeapRegion* start_region = _hrm.addr_to_region(start_address); 729 if ((prev_last_region != NULL) && (start_region == prev_last_region)) { 730 start_address = start_region->end(); 731 if (start_address > last_address) { 732 increase_used(word_size * HeapWordSize); 733 start_region->set_top(last_address + 1); 734 continue; 735 } 736 start_region->set_top(start_address); 737 curr_range = MemRegion(start_address, last_address + 1); 738 start_region = _hrm.addr_to_region(start_address); 739 } 740 741 // Perform the actual region allocation, exiting if it fails. 742 // Then note how much new space we have allocated. 743 if (!_hrm.allocate_containing_regions(curr_range, &commits, workers())) { 744 return false; 745 } 746 increase_used(word_size * HeapWordSize); 747 if (commits != 0) { 748 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B", 749 HeapRegion::GrainWords * HeapWordSize * commits); 750 751 } 752 753 // Mark each G1 region touched by the range as archive, add it to the old set, 754 // and set the allocation context and top. 755 HeapRegion* curr_region = _hrm.addr_to_region(start_address); 756 HeapRegion* last_region = _hrm.addr_to_region(last_address); 757 prev_last_region = last_region; 758 759 while (curr_region != NULL) { 760 assert(curr_region->is_empty() && !curr_region->is_pinned(), 761 "Region already in use (index %u)", curr_region->hrm_index()); 762 curr_region->set_allocation_context(AllocationContext::system()); 763 curr_region->set_archive(); 764 _hr_printer.alloc(curr_region); 765 _old_set.add(curr_region); 766 if (curr_region != last_region) { 767 curr_region->set_top(curr_region->end()); 768 curr_region = _hrm.next_region_in_heap(curr_region); 769 } else { 770 curr_region->set_top(last_address + 1); 771 curr_region = NULL; 772 } 773 } 774 775 // Notify mark-sweep of the archive range. 776 G1MarkSweep::set_range_archive(curr_range, true); 777 } 778 return true; 779 } 780 781 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) { 782 assert(!is_init_completed(), "Expect to be called at JVM init time"); 783 assert(ranges != NULL, "MemRegion array NULL"); 784 assert(count != 0, "No MemRegions provided"); 785 MemRegion reserved = _hrm.reserved(); 786 HeapWord *prev_last_addr = NULL; 787 HeapRegion* prev_last_region = NULL; 788 789 // For each MemRegion, create filler objects, if needed, in the G1 regions 790 // that contain the address range. The address range actually within the 791 // MemRegion will not be modified. That is assumed to have been initialized 792 // elsewhere, probably via an mmap of archived heap data. 793 MutexLockerEx x(Heap_lock); 794 for (size_t i = 0; i < count; i++) { 795 HeapWord* start_address = ranges[i].start(); 796 HeapWord* last_address = ranges[i].last(); 797 798 assert(reserved.contains(start_address) && reserved.contains(last_address), 799 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 800 p2i(start_address), p2i(last_address)); 801 assert(start_address > prev_last_addr, 802 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 803 p2i(start_address), p2i(prev_last_addr)); 804 805 HeapRegion* start_region = _hrm.addr_to_region(start_address); 806 HeapRegion* last_region = _hrm.addr_to_region(last_address); 807 HeapWord* bottom_address = start_region->bottom(); 808 809 // Check for a range beginning in the same region in which the 810 // previous one ended. 811 if (start_region == prev_last_region) { 812 bottom_address = prev_last_addr + 1; 813 } 814 815 // Verify that the regions were all marked as archive regions by 816 // alloc_archive_regions. 817 HeapRegion* curr_region = start_region; 818 while (curr_region != NULL) { 819 guarantee(curr_region->is_archive(), 820 "Expected archive region at index %u", curr_region->hrm_index()); 821 if (curr_region != last_region) { 822 curr_region = _hrm.next_region_in_heap(curr_region); 823 } else { 824 curr_region = NULL; 825 } 826 } 827 828 prev_last_addr = last_address; 829 prev_last_region = last_region; 830 831 // Fill the memory below the allocated range with dummy object(s), 832 // if the region bottom does not match the range start, or if the previous 833 // range ended within the same G1 region, and there is a gap. 834 if (start_address != bottom_address) { 835 size_t fill_size = pointer_delta(start_address, bottom_address); 836 G1CollectedHeap::fill_with_objects(bottom_address, fill_size); 837 increase_used(fill_size * HeapWordSize); 838 } 839 } 840 } 841 842 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size, 843 uint* gc_count_before_ret, 844 uint* gclocker_retry_count_ret) { 845 assert_heap_not_locked_and_not_at_safepoint(); 846 assert(!is_humongous(word_size), "attempt_allocation() should not " 847 "be called for humongous allocation requests"); 848 849 AllocationContext_t context = AllocationContext::current(); 850 HeapWord* result = _allocator->attempt_allocation(word_size, context); 851 852 if (result == NULL) { 853 result = attempt_allocation_slow(word_size, 854 context, 855 gc_count_before_ret, 856 gclocker_retry_count_ret); 857 } 858 assert_heap_not_locked(); 859 if (result != NULL) { 860 dirty_young_block(result, word_size); 861 } 862 return result; 863 } 864 865 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) { 866 assert(!is_init_completed(), "Expect to be called at JVM init time"); 867 assert(ranges != NULL, "MemRegion array NULL"); 868 assert(count != 0, "No MemRegions provided"); 869 MemRegion reserved = _hrm.reserved(); 870 HeapWord* prev_last_addr = NULL; 871 HeapRegion* prev_last_region = NULL; 872 size_t size_used = 0; 873 size_t uncommitted_regions = 0; 874 875 // For each Memregion, free the G1 regions that constitute it, and 876 // notify mark-sweep that the range is no longer to be considered 'archive.' 877 MutexLockerEx x(Heap_lock); 878 for (size_t i = 0; i < count; i++) { 879 HeapWord* start_address = ranges[i].start(); 880 HeapWord* last_address = ranges[i].last(); 881 882 assert(reserved.contains(start_address) && reserved.contains(last_address), 883 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 884 p2i(start_address), p2i(last_address)); 885 assert(start_address > prev_last_addr, 886 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 887 p2i(start_address), p2i(prev_last_addr)); 888 size_used += ranges[i].byte_size(); 889 prev_last_addr = last_address; 890 891 HeapRegion* start_region = _hrm.addr_to_region(start_address); 892 HeapRegion* last_region = _hrm.addr_to_region(last_address); 893 894 // Check for ranges that start in the same G1 region in which the previous 895 // range ended, and adjust the start address so we don't try to free 896 // the same region again. If the current range is entirely within that 897 // region, skip it. 898 if (start_region == prev_last_region) { 899 start_address = start_region->end(); 900 if (start_address > last_address) { 901 continue; 902 } 903 start_region = _hrm.addr_to_region(start_address); 904 } 905 prev_last_region = last_region; 906 907 // After verifying that each region was marked as an archive region by 908 // alloc_archive_regions, set it free and empty and uncommit it. 909 HeapRegion* curr_region = start_region; 910 while (curr_region != NULL) { 911 guarantee(curr_region->is_archive(), 912 "Expected archive region at index %u", curr_region->hrm_index()); 913 uint curr_index = curr_region->hrm_index(); 914 _old_set.remove(curr_region); 915 curr_region->set_free(); 916 curr_region->set_top(curr_region->bottom()); 917 if (curr_region != last_region) { 918 curr_region = _hrm.next_region_in_heap(curr_region); 919 } else { 920 curr_region = NULL; 921 } 922 _hrm.shrink_at(curr_index, 1); 923 uncommitted_regions++; 924 } 925 926 // Notify mark-sweep that this is no longer an archive range. 927 G1MarkSweep::set_range_archive(ranges[i], false); 928 } 929 930 if (uncommitted_regions != 0) { 931 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B", 932 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions); 933 } 934 decrease_used(size_used); 935 } 936 937 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size, 938 uint* gc_count_before_ret, 939 uint* gclocker_retry_count_ret) { 940 // The structure of this method has a lot of similarities to 941 // attempt_allocation_slow(). The reason these two were not merged 942 // into a single one is that such a method would require several "if 943 // allocation is not humongous do this, otherwise do that" 944 // conditional paths which would obscure its flow. In fact, an early 945 // version of this code did use a unified method which was harder to 946 // follow and, as a result, it had subtle bugs that were hard to 947 // track down. So keeping these two methods separate allows each to 948 // be more readable. It will be good to keep these two in sync as 949 // much as possible. 950 951 assert_heap_not_locked_and_not_at_safepoint(); 952 assert(is_humongous(word_size), "attempt_allocation_humongous() " 953 "should only be called for humongous allocations"); 954 955 // Humongous objects can exhaust the heap quickly, so we should check if we 956 // need to start a marking cycle at each humongous object allocation. We do 957 // the check before we do the actual allocation. The reason for doing it 958 // before the allocation is that we avoid having to keep track of the newly 959 // allocated memory while we do a GC. 960 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation", 961 word_size)) { 962 collect(GCCause::_g1_humongous_allocation); 963 } 964 965 // We will loop until a) we manage to successfully perform the 966 // allocation or b) we successfully schedule a collection which 967 // fails to perform the allocation. b) is the only case when we'll 968 // return NULL. 969 HeapWord* result = NULL; 970 for (int try_count = 1; /* we'll return */; try_count += 1) { 971 bool should_try_gc; 972 uint gc_count_before; 973 974 { 975 MutexLockerEx x(Heap_lock); 976 977 // Given that humongous objects are not allocated in young 978 // regions, we'll first try to do the allocation without doing a 979 // collection hoping that there's enough space in the heap. 980 result = humongous_obj_allocate(word_size, AllocationContext::current()); 981 if (result != NULL) { 982 size_t size_in_regions = humongous_obj_size_in_regions(word_size); 983 g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes); 984 return result; 985 } 986 987 if (GCLocker::is_active_and_needs_gc()) { 988 should_try_gc = false; 989 } else { 990 // The GCLocker may not be active but the GCLocker initiated 991 // GC may not yet have been performed (GCLocker::needs_gc() 992 // returns true). In this case we do not try this GC and 993 // wait until the GCLocker initiated GC is performed, and 994 // then retry the allocation. 995 if (GCLocker::needs_gc()) { 996 should_try_gc = false; 997 } else { 998 // Read the GC count while still holding the Heap_lock. 999 gc_count_before = total_collections(); 1000 should_try_gc = true; 1001 } 1002 } 1003 } 1004 1005 if (should_try_gc) { 1006 // If we failed to allocate the humongous object, we should try to 1007 // do a collection pause (if we're allowed) in case it reclaims 1008 // enough space for the allocation to succeed after the pause. 1009 1010 bool succeeded; 1011 result = do_collection_pause(word_size, gc_count_before, &succeeded, 1012 GCCause::_g1_humongous_allocation); 1013 if (result != NULL) { 1014 assert(succeeded, "only way to get back a non-NULL result"); 1015 return result; 1016 } 1017 1018 if (succeeded) { 1019 // If we get here we successfully scheduled a collection which 1020 // failed to allocate. No point in trying to allocate 1021 // further. We'll just return NULL. 1022 MutexLockerEx x(Heap_lock); 1023 *gc_count_before_ret = total_collections(); 1024 return NULL; 1025 } 1026 } else { 1027 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { 1028 MutexLockerEx x(Heap_lock); 1029 *gc_count_before_ret = total_collections(); 1030 return NULL; 1031 } 1032 // The GCLocker is either active or the GCLocker initiated 1033 // GC has not yet been performed. Stall until it is and 1034 // then retry the allocation. 1035 GCLocker::stall_until_clear(); 1036 (*gclocker_retry_count_ret) += 1; 1037 } 1038 1039 // We can reach here if we were unsuccessful in scheduling a 1040 // collection (because another thread beat us to it) or if we were 1041 // stalled due to the GC locker. In either can we should retry the 1042 // allocation attempt in case another thread successfully 1043 // performed a collection and reclaimed enough space. Give a 1044 // warning if we seem to be looping forever. 1045 1046 if ((QueuedAllocationWarningCount > 0) && 1047 (try_count % QueuedAllocationWarningCount == 0)) { 1048 log_warning(gc)("G1CollectedHeap::attempt_allocation_humongous() " 1049 "retries %d times", try_count); 1050 } 1051 } 1052 1053 ShouldNotReachHere(); 1054 return NULL; 1055 } 1056 1057 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size, 1058 AllocationContext_t context, 1059 bool expect_null_mutator_alloc_region) { 1060 assert_at_safepoint(true /* should_be_vm_thread */); 1061 assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region, 1062 "the current alloc region was unexpectedly found to be non-NULL"); 1063 1064 if (!is_humongous(word_size)) { 1065 return _allocator->attempt_allocation_locked(word_size, context); 1066 } else { 1067 HeapWord* result = humongous_obj_allocate(word_size, context); 1068 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) { 1069 collector_state()->set_initiate_conc_mark_if_possible(true); 1070 } 1071 return result; 1072 } 1073 1074 ShouldNotReachHere(); 1075 } 1076 1077 class PostMCRemSetClearClosure: public HeapRegionClosure { 1078 G1CollectedHeap* _g1h; 1079 ModRefBarrierSet* _mr_bs; 1080 public: 1081 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) : 1082 _g1h(g1h), _mr_bs(mr_bs) {} 1083 1084 bool doHeapRegion(HeapRegion* r) { 1085 HeapRegionRemSet* hrrs = r->rem_set(); 1086 1087 _g1h->reset_gc_time_stamps(r); 1088 1089 if (r->is_continues_humongous()) { 1090 // We'll assert that the strong code root list and RSet is empty 1091 assert(hrrs->strong_code_roots_list_length() == 0, "sanity"); 1092 assert(hrrs->occupied() == 0, "RSet should be empty"); 1093 } else { 1094 hrrs->clear(); 1095 } 1096 // You might think here that we could clear just the cards 1097 // corresponding to the used region. But no: if we leave a dirty card 1098 // in a region we might allocate into, then it would prevent that card 1099 // from being enqueued, and cause it to be missed. 1100 // Re: the performance cost: we shouldn't be doing full GC anyway! 1101 _mr_bs->clear(MemRegion(r->bottom(), r->end())); 1102 1103 return false; 1104 } 1105 }; 1106 1107 void G1CollectedHeap::clear_rsets_post_compaction() { 1108 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set()); 1109 heap_region_iterate(&rs_clear); 1110 } 1111 1112 class RebuildRSOutOfRegionClosure: public HeapRegionClosure { 1113 G1CollectedHeap* _g1h; 1114 UpdateRSOopClosure _cl; 1115 public: 1116 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) : 1117 _cl(g1->g1_rem_set(), worker_i), 1118 _g1h(g1) 1119 { } 1120 1121 bool doHeapRegion(HeapRegion* r) { 1122 if (!r->is_continues_humongous()) { 1123 _cl.set_from(r); 1124 r->oop_iterate(&_cl); 1125 } 1126 return false; 1127 } 1128 }; 1129 1130 class ParRebuildRSTask: public AbstractGangTask { 1131 G1CollectedHeap* _g1; 1132 HeapRegionClaimer _hrclaimer; 1133 1134 public: 1135 ParRebuildRSTask(G1CollectedHeap* g1) : 1136 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {} 1137 1138 void work(uint worker_id) { 1139 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id); 1140 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer); 1141 } 1142 }; 1143 1144 class PostCompactionPrinterClosure: public HeapRegionClosure { 1145 private: 1146 G1HRPrinter* _hr_printer; 1147 public: 1148 bool doHeapRegion(HeapRegion* hr) { 1149 assert(!hr->is_young(), "not expecting to find young regions"); 1150 _hr_printer->post_compaction(hr); 1151 return false; 1152 } 1153 1154 PostCompactionPrinterClosure(G1HRPrinter* hr_printer) 1155 : _hr_printer(hr_printer) { } 1156 }; 1157 1158 void G1CollectedHeap::print_hrm_post_compaction() { 1159 if (_hr_printer.is_active()) { 1160 PostCompactionPrinterClosure cl(hr_printer()); 1161 heap_region_iterate(&cl); 1162 } 1163 1164 } 1165 1166 bool G1CollectedHeap::do_full_collection(bool explicit_gc, 1167 bool clear_all_soft_refs) { 1168 assert_at_safepoint(true /* should_be_vm_thread */); 1169 1170 if (GCLocker::check_active_before_gc()) { 1171 return false; 1172 } 1173 1174 STWGCTimer* gc_timer = G1MarkSweep::gc_timer(); 1175 gc_timer->register_gc_start(); 1176 1177 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer(); 1178 GCIdMark gc_id_mark; 1179 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start()); 1180 1181 SvcGCMarker sgcm(SvcGCMarker::FULL); 1182 ResourceMark rm; 1183 1184 print_heap_before_gc(); 1185 print_heap_regions(); 1186 trace_heap_before_gc(gc_tracer); 1187 1188 size_t metadata_prev_used = MetaspaceAux::used_bytes(); 1189 1190 _verifier->verify_region_sets_optional(); 1191 1192 const bool do_clear_all_soft_refs = clear_all_soft_refs || 1193 collector_policy()->should_clear_all_soft_refs(); 1194 1195 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy()); 1196 1197 { 1198 IsGCActiveMark x; 1199 1200 // Timing 1201 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant"); 1202 GCTraceCPUTime tcpu; 1203 1204 { 1205 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true); 1206 TraceCollectorStats tcs(g1mm()->full_collection_counters()); 1207 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause()); 1208 1209 G1HeapTransition heap_transition(this); 1210 g1_policy()->record_full_collection_start(); 1211 1212 // Note: When we have a more flexible GC logging framework that 1213 // allows us to add optional attributes to a GC log record we 1214 // could consider timing and reporting how long we wait in the 1215 // following two methods. 1216 wait_while_free_regions_coming(); 1217 // If we start the compaction before the CM threads finish 1218 // scanning the root regions we might trip them over as we'll 1219 // be moving objects / updating references. So let's wait until 1220 // they are done. By telling them to abort, they should complete 1221 // early. 1222 _cm->root_regions()->abort(); 1223 _cm->root_regions()->wait_until_scan_finished(); 1224 append_secondary_free_list_if_not_empty_with_lock(); 1225 1226 gc_prologue(true); 1227 increment_total_collections(true /* full gc */); 1228 increment_old_marking_cycles_started(); 1229 1230 assert(used() == recalculate_used(), "Should be equal"); 1231 1232 _verifier->verify_before_gc(); 1233 1234 _verifier->check_bitmaps("Full GC Start"); 1235 pre_full_gc_dump(gc_timer); 1236 1237 #if defined(COMPILER2) || INCLUDE_JVMCI 1238 DerivedPointerTable::clear(); 1239 #endif 1240 1241 // Disable discovery and empty the discovered lists 1242 // for the CM ref processor. 1243 ref_processor_cm()->disable_discovery(); 1244 ref_processor_cm()->abandon_partial_discovery(); 1245 ref_processor_cm()->verify_no_references_recorded(); 1246 1247 // Abandon current iterations of concurrent marking and concurrent 1248 // refinement, if any are in progress. 1249 concurrent_mark()->abort(); 1250 1251 // Make sure we'll choose a new allocation region afterwards. 1252 _allocator->release_mutator_alloc_region(); 1253 _allocator->abandon_gc_alloc_regions(); 1254 g1_rem_set()->cleanupHRRS(); 1255 1256 // We may have added regions to the current incremental collection 1257 // set between the last GC or pause and now. We need to clear the 1258 // incremental collection set and then start rebuilding it afresh 1259 // after this full GC. 1260 abandon_collection_set(collection_set()); 1261 1262 tear_down_region_sets(false /* free_list_only */); 1263 collector_state()->set_gcs_are_young(true); 1264 1265 // See the comments in g1CollectedHeap.hpp and 1266 // G1CollectedHeap::ref_processing_init() about 1267 // how reference processing currently works in G1. 1268 1269 // Temporarily make discovery by the STW ref processor single threaded (non-MT). 1270 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false); 1271 1272 // Temporarily clear the STW ref processor's _is_alive_non_header field. 1273 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL); 1274 1275 ref_processor_stw()->enable_discovery(); 1276 ref_processor_stw()->setup_policy(do_clear_all_soft_refs); 1277 1278 // Do collection work 1279 { 1280 HandleMark hm; // Discard invalid handles created during gc 1281 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs); 1282 } 1283 1284 assert(num_free_regions() == 0, "we should not have added any free regions"); 1285 rebuild_region_sets(false /* free_list_only */); 1286 1287 // Enqueue any discovered reference objects that have 1288 // not been removed from the discovered lists. 1289 ref_processor_stw()->enqueue_discovered_references(); 1290 1291 #if defined(COMPILER2) || INCLUDE_JVMCI 1292 DerivedPointerTable::update_pointers(); 1293 #endif 1294 1295 MemoryService::track_memory_usage(); 1296 1297 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 1298 ref_processor_stw()->verify_no_references_recorded(); 1299 1300 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 1301 ClassLoaderDataGraph::purge(); 1302 MetaspaceAux::verify_metrics(); 1303 1304 // Note: since we've just done a full GC, concurrent 1305 // marking is no longer active. Therefore we need not 1306 // re-enable reference discovery for the CM ref processor. 1307 // That will be done at the start of the next marking cycle. 1308 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition"); 1309 ref_processor_cm()->verify_no_references_recorded(); 1310 1311 reset_gc_time_stamp(); 1312 // Since everything potentially moved, we will clear all remembered 1313 // sets, and clear all cards. Later we will rebuild remembered 1314 // sets. We will also reset the GC time stamps of the regions. 1315 clear_rsets_post_compaction(); 1316 check_gc_time_stamps(); 1317 1318 resize_if_necessary_after_full_collection(); 1319 1320 // We should do this after we potentially resize the heap so 1321 // that all the COMMIT / UNCOMMIT events are generated before 1322 // the compaction events. 1323 print_hrm_post_compaction(); 1324 1325 if (_hot_card_cache->use_cache()) { 1326 _hot_card_cache->reset_card_counts(); 1327 _hot_card_cache->reset_hot_cache(); 1328 } 1329 1330 // Rebuild remembered sets of all regions. 1331 uint n_workers = 1332 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 1333 workers()->active_workers(), 1334 Threads::number_of_non_daemon_threads()); 1335 workers()->update_active_workers(n_workers); 1336 log_info(gc,task)("Using %u workers of %u to rebuild remembered set", n_workers, workers()->total_workers()); 1337 1338 ParRebuildRSTask rebuild_rs_task(this); 1339 workers()->run_task(&rebuild_rs_task); 1340 1341 // Rebuild the strong code root lists for each region 1342 rebuild_strong_code_roots(); 1343 1344 if (true) { // FIXME 1345 MetaspaceGC::compute_new_size(); 1346 } 1347 1348 #ifdef TRACESPINNING 1349 ParallelTaskTerminator::print_termination_counts(); 1350 #endif 1351 1352 // Discard all rset updates 1353 JavaThread::dirty_card_queue_set().abandon_logs(); 1354 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty"); 1355 1356 // At this point there should be no regions in the 1357 // entire heap tagged as young. 1358 assert(check_young_list_empty(), "young list should be empty at this point"); 1359 1360 // Update the number of full collections that have been completed. 1361 increment_old_marking_cycles_completed(false /* concurrent */); 1362 1363 _hrm.verify_optional(); 1364 _verifier->verify_region_sets_optional(); 1365 1366 _verifier->verify_after_gc(); 1367 1368 // Clear the previous marking bitmap, if needed for bitmap verification. 1369 // Note we cannot do this when we clear the next marking bitmap in 1370 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the 1371 // objects marked during a full GC against the previous bitmap. 1372 // But we need to clear it before calling check_bitmaps below since 1373 // the full GC has compacted objects and updated TAMS but not updated 1374 // the prev bitmap. 1375 if (G1VerifyBitmaps) { 1376 GCTraceTime(Debug, gc)("Clear Bitmap for Verification"); 1377 _cm->clear_prev_bitmap(workers()); 1378 } 1379 _verifier->check_bitmaps("Full GC End"); 1380 1381 // Start a new incremental collection set for the next pause 1382 collection_set()->start_incremental_building(); 1383 1384 clear_cset_fast_test(); 1385 1386 _allocator->init_mutator_alloc_region(); 1387 1388 g1_policy()->record_full_collection_end(); 1389 1390 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 1391 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 1392 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 1393 // before any GC notifications are raised. 1394 g1mm()->update_sizes(); 1395 1396 gc_epilogue(true); 1397 1398 heap_transition.print(); 1399 1400 print_heap_after_gc(); 1401 print_heap_regions(); 1402 trace_heap_after_gc(gc_tracer); 1403 1404 post_full_gc_dump(gc_timer); 1405 } 1406 1407 gc_timer->register_gc_end(); 1408 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions()); 1409 } 1410 1411 return true; 1412 } 1413 1414 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) { 1415 // Currently, there is no facility in the do_full_collection(bool) API to notify 1416 // the caller that the collection did not succeed (e.g., because it was locked 1417 // out by the GC locker). So, right now, we'll ignore the return value. 1418 bool dummy = do_full_collection(true, /* explicit_gc */ 1419 clear_all_soft_refs); 1420 } 1421 1422 void G1CollectedHeap::resize_if_necessary_after_full_collection() { 1423 // Include bytes that will be pre-allocated to support collections, as "used". 1424 const size_t used_after_gc = used(); 1425 const size_t capacity_after_gc = capacity(); 1426 const size_t free_after_gc = capacity_after_gc - used_after_gc; 1427 1428 // This is enforced in arguments.cpp. 1429 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, 1430 "otherwise the code below doesn't make sense"); 1431 1432 // We don't have floating point command-line arguments 1433 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0; 1434 const double maximum_used_percentage = 1.0 - minimum_free_percentage; 1435 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0; 1436 const double minimum_used_percentage = 1.0 - maximum_free_percentage; 1437 1438 const size_t min_heap_size = collector_policy()->min_heap_byte_size(); 1439 const size_t max_heap_size = collector_policy()->max_heap_byte_size(); 1440 1441 // We have to be careful here as these two calculations can overflow 1442 // 32-bit size_t's. 1443 double used_after_gc_d = (double) used_after_gc; 1444 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage; 1445 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage; 1446 1447 // Let's make sure that they are both under the max heap size, which 1448 // by default will make them fit into a size_t. 1449 double desired_capacity_upper_bound = (double) max_heap_size; 1450 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d, 1451 desired_capacity_upper_bound); 1452 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d, 1453 desired_capacity_upper_bound); 1454 1455 // We can now safely turn them into size_t's. 1456 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d; 1457 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d; 1458 1459 // This assert only makes sense here, before we adjust them 1460 // with respect to the min and max heap size. 1461 assert(minimum_desired_capacity <= maximum_desired_capacity, 1462 "minimum_desired_capacity = " SIZE_FORMAT ", " 1463 "maximum_desired_capacity = " SIZE_FORMAT, 1464 minimum_desired_capacity, maximum_desired_capacity); 1465 1466 // Should not be greater than the heap max size. No need to adjust 1467 // it with respect to the heap min size as it's a lower bound (i.e., 1468 // we'll try to make the capacity larger than it, not smaller). 1469 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size); 1470 // Should not be less than the heap min size. No need to adjust it 1471 // with respect to the heap max size as it's an upper bound (i.e., 1472 // we'll try to make the capacity smaller than it, not greater). 1473 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size); 1474 1475 if (capacity_after_gc < minimum_desired_capacity) { 1476 // Don't expand unless it's significant 1477 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc; 1478 1479 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). " 1480 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)", 1481 capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio); 1482 1483 expand(expand_bytes, _workers); 1484 1485 // No expansion, now see if we want to shrink 1486 } else if (capacity_after_gc > maximum_desired_capacity) { 1487 // Capacity too large, compute shrinking size 1488 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity; 1489 1490 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). " 1491 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)", 1492 capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio); 1493 1494 shrink(shrink_bytes); 1495 } 1496 } 1497 1498 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size, 1499 AllocationContext_t context, 1500 bool do_gc, 1501 bool clear_all_soft_refs, 1502 bool expect_null_mutator_alloc_region, 1503 bool* gc_succeeded) { 1504 *gc_succeeded = true; 1505 // Let's attempt the allocation first. 1506 HeapWord* result = 1507 attempt_allocation_at_safepoint(word_size, 1508 context, 1509 expect_null_mutator_alloc_region); 1510 if (result != NULL) { 1511 assert(*gc_succeeded, "sanity"); 1512 return result; 1513 } 1514 1515 // In a G1 heap, we're supposed to keep allocation from failing by 1516 // incremental pauses. Therefore, at least for now, we'll favor 1517 // expansion over collection. (This might change in the future if we can 1518 // do something smarter than full collection to satisfy a failed alloc.) 1519 result = expand_and_allocate(word_size, context); 1520 if (result != NULL) { 1521 assert(*gc_succeeded, "sanity"); 1522 return result; 1523 } 1524 1525 if (do_gc) { 1526 // Expansion didn't work, we'll try to do a Full GC. 1527 *gc_succeeded = do_full_collection(false, /* explicit_gc */ 1528 clear_all_soft_refs); 1529 } 1530 1531 return NULL; 1532 } 1533 1534 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size, 1535 AllocationContext_t context, 1536 bool* succeeded) { 1537 assert_at_safepoint(true /* should_be_vm_thread */); 1538 1539 // Attempts to allocate followed by Full GC. 1540 HeapWord* result = 1541 satisfy_failed_allocation_helper(word_size, 1542 context, 1543 true, /* do_gc */ 1544 false, /* clear_all_soft_refs */ 1545 false, /* expect_null_mutator_alloc_region */ 1546 succeeded); 1547 1548 if (result != NULL || !*succeeded) { 1549 return result; 1550 } 1551 1552 // Attempts to allocate followed by Full GC that will collect all soft references. 1553 result = satisfy_failed_allocation_helper(word_size, 1554 context, 1555 true, /* do_gc */ 1556 true, /* clear_all_soft_refs */ 1557 true, /* expect_null_mutator_alloc_region */ 1558 succeeded); 1559 1560 if (result != NULL || !*succeeded) { 1561 return result; 1562 } 1563 1564 // Attempts to allocate, no GC 1565 result = satisfy_failed_allocation_helper(word_size, 1566 context, 1567 false, /* do_gc */ 1568 false, /* clear_all_soft_refs */ 1569 true, /* expect_null_mutator_alloc_region */ 1570 succeeded); 1571 1572 if (result != NULL) { 1573 assert(*succeeded, "sanity"); 1574 return result; 1575 } 1576 1577 assert(!collector_policy()->should_clear_all_soft_refs(), 1578 "Flag should have been handled and cleared prior to this point"); 1579 1580 // What else? We might try synchronous finalization later. If the total 1581 // space available is large enough for the allocation, then a more 1582 // complete compaction phase than we've tried so far might be 1583 // appropriate. 1584 assert(*succeeded, "sanity"); 1585 return NULL; 1586 } 1587 1588 // Attempting to expand the heap sufficiently 1589 // to support an allocation of the given "word_size". If 1590 // successful, perform the allocation and return the address of the 1591 // allocated block, or else "NULL". 1592 1593 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) { 1594 assert_at_safepoint(true /* should_be_vm_thread */); 1595 1596 _verifier->verify_region_sets_optional(); 1597 1598 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes); 1599 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B", 1600 word_size * HeapWordSize); 1601 1602 1603 if (expand(expand_bytes, _workers)) { 1604 _hrm.verify_optional(); 1605 _verifier->verify_region_sets_optional(); 1606 return attempt_allocation_at_safepoint(word_size, 1607 context, 1608 false /* expect_null_mutator_alloc_region */); 1609 } 1610 return NULL; 1611 } 1612 1613 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) { 1614 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); 1615 aligned_expand_bytes = align_size_up(aligned_expand_bytes, 1616 HeapRegion::GrainBytes); 1617 1618 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount:" SIZE_FORMAT "B expansion amount:" SIZE_FORMAT "B", 1619 expand_bytes, aligned_expand_bytes); 1620 1621 if (is_maximal_no_gc()) { 1622 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)"); 1623 return false; 1624 } 1625 1626 double expand_heap_start_time_sec = os::elapsedTime(); 1627 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes); 1628 assert(regions_to_expand > 0, "Must expand by at least one region"); 1629 1630 uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers); 1631 if (expand_time_ms != NULL) { 1632 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS; 1633 } 1634 1635 if (expanded_by > 0) { 1636 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes; 1637 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition"); 1638 g1_policy()->record_new_heap_size(num_regions()); 1639 } else { 1640 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)"); 1641 1642 // The expansion of the virtual storage space was unsuccessful. 1643 // Let's see if it was because we ran out of swap. 1644 if (G1ExitOnExpansionFailure && 1645 _hrm.available() >= regions_to_expand) { 1646 // We had head room... 1647 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion"); 1648 } 1649 } 1650 return regions_to_expand > 0; 1651 } 1652 1653 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) { 1654 size_t aligned_shrink_bytes = 1655 ReservedSpace::page_align_size_down(shrink_bytes); 1656 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes, 1657 HeapRegion::GrainBytes); 1658 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes); 1659 1660 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove); 1661 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes; 1662 1663 1664 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", 1665 shrink_bytes, aligned_shrink_bytes, shrunk_bytes); 1666 if (num_regions_removed > 0) { 1667 g1_policy()->record_new_heap_size(num_regions()); 1668 } else { 1669 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)"); 1670 } 1671 } 1672 1673 void G1CollectedHeap::shrink(size_t shrink_bytes) { 1674 _verifier->verify_region_sets_optional(); 1675 1676 // We should only reach here at the end of a Full GC which means we 1677 // should not not be holding to any GC alloc regions. The method 1678 // below will make sure of that and do any remaining clean up. 1679 _allocator->abandon_gc_alloc_regions(); 1680 1681 // Instead of tearing down / rebuilding the free lists here, we 1682 // could instead use the remove_all_pending() method on free_list to 1683 // remove only the ones that we need to remove. 1684 tear_down_region_sets(true /* free_list_only */); 1685 shrink_helper(shrink_bytes); 1686 rebuild_region_sets(true /* free_list_only */); 1687 1688 _hrm.verify_optional(); 1689 _verifier->verify_region_sets_optional(); 1690 } 1691 1692 // Public methods. 1693 1694 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) : 1695 CollectedHeap(), 1696 _collector_policy(collector_policy), 1697 _g1_policy(create_g1_policy()), 1698 _collection_set(this, _g1_policy), 1699 _dirty_card_queue_set(false), 1700 _is_alive_closure_cm(this), 1701 _is_alive_closure_stw(this), 1702 _ref_processor_cm(NULL), 1703 _ref_processor_stw(NULL), 1704 _bot(NULL), 1705 _hot_card_cache(NULL), 1706 _g1_rem_set(NULL), 1707 _cg1r(NULL), 1708 _g1mm(NULL), 1709 _refine_cte_cl(NULL), 1710 _preserved_marks_set(true /* in_c_heap */), 1711 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()), 1712 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()), 1713 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()), 1714 _humongous_reclaim_candidates(), 1715 _has_humongous_reclaim_candidates(false), 1716 _archive_allocator(NULL), 1717 _free_regions_coming(false), 1718 _gc_time_stamp(0), 1719 _summary_bytes_used(0), 1720 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight), 1721 _old_evac_stats("Old", OldPLABSize, PLABWeight), 1722 _expand_heap_after_alloc_failure(true), 1723 _old_marking_cycles_started(0), 1724 _old_marking_cycles_completed(0), 1725 _in_cset_fast_test(), 1726 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()), 1727 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()) { 1728 1729 _workers = new WorkGang("GC Thread", ParallelGCThreads, 1730 /* are_GC_task_threads */true, 1731 /* are_ConcurrentGC_threads */false); 1732 _workers->initialize_workers(); 1733 _verifier = new G1HeapVerifier(this); 1734 1735 _allocator = G1Allocator::create_allocator(this); 1736 1737 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics()); 1738 1739 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords); 1740 1741 // Override the default _filler_array_max_size so that no humongous filler 1742 // objects are created. 1743 _filler_array_max_size = _humongous_object_threshold_in_words; 1744 1745 uint n_queues = ParallelGCThreads; 1746 _task_queues = new RefToScanQueueSet(n_queues); 1747 1748 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC); 1749 1750 for (uint i = 0; i < n_queues; i++) { 1751 RefToScanQueue* q = new RefToScanQueue(); 1752 q->initialize(); 1753 _task_queues->register_queue(i, q); 1754 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo(); 1755 } 1756 1757 // Initialize the G1EvacuationFailureALot counters and flags. 1758 NOT_PRODUCT(reset_evacuation_should_fail();) 1759 1760 guarantee(_task_queues != NULL, "task_queues allocation failure."); 1761 } 1762 1763 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description, 1764 size_t size, 1765 size_t translation_factor) { 1766 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1); 1767 // Allocate a new reserved space, preferring to use large pages. 1768 ReservedSpace rs(size, preferred_page_size); 1769 G1RegionToSpaceMapper* result = 1770 G1RegionToSpaceMapper::create_mapper(rs, 1771 size, 1772 rs.alignment(), 1773 HeapRegion::GrainBytes, 1774 translation_factor, 1775 mtGC); 1776 1777 os::trace_page_sizes_for_requested_size(description, 1778 size, 1779 preferred_page_size, 1780 rs.alignment(), 1781 rs.base(), 1782 rs.size()); 1783 1784 return result; 1785 } 1786 1787 jint G1CollectedHeap::initialize() { 1788 CollectedHeap::pre_initialize(); 1789 os::enable_vtime(); 1790 1791 // Necessary to satisfy locking discipline assertions. 1792 1793 MutexLocker x(Heap_lock); 1794 1795 // While there are no constraints in the GC code that HeapWordSize 1796 // be any particular value, there are multiple other areas in the 1797 // system which believe this to be true (e.g. oop->object_size in some 1798 // cases incorrectly returns the size in wordSize units rather than 1799 // HeapWordSize). 1800 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 1801 1802 size_t init_byte_size = collector_policy()->initial_heap_byte_size(); 1803 size_t max_byte_size = collector_policy()->max_heap_byte_size(); 1804 size_t heap_alignment = collector_policy()->heap_alignment(); 1805 1806 // Ensure that the sizes are properly aligned. 1807 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1808 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1809 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap"); 1810 1811 _refine_cte_cl = new RefineCardTableEntryClosure(); 1812 1813 jint ecode = JNI_OK; 1814 _cg1r = ConcurrentG1Refine::create(_refine_cte_cl, &ecode); 1815 if (_cg1r == NULL) { 1816 return ecode; 1817 } 1818 1819 // Reserve the maximum. 1820 1821 // When compressed oops are enabled, the preferred heap base 1822 // is calculated by subtracting the requested size from the 1823 // 32Gb boundary and using the result as the base address for 1824 // heap reservation. If the requested size is not aligned to 1825 // HeapRegion::GrainBytes (i.e. the alignment that is passed 1826 // into the ReservedHeapSpace constructor) then the actual 1827 // base of the reserved heap may end up differing from the 1828 // address that was requested (i.e. the preferred heap base). 1829 // If this happens then we could end up using a non-optimal 1830 // compressed oops mode. 1831 1832 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size, 1833 heap_alignment); 1834 1835 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size())); 1836 1837 // Create the barrier set for the entire reserved region. 1838 G1SATBCardTableLoggingModRefBS* bs 1839 = new G1SATBCardTableLoggingModRefBS(reserved_region()); 1840 bs->initialize(); 1841 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity"); 1842 set_barrier_set(bs); 1843 1844 // Create the hot card cache. 1845 _hot_card_cache = new G1HotCardCache(this); 1846 1847 // Also create a G1 rem set. 1848 _g1_rem_set = new G1RemSet(this, g1_barrier_set(), _hot_card_cache); 1849 1850 // Carve out the G1 part of the heap. 1851 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size); 1852 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size(); 1853 G1RegionToSpaceMapper* heap_storage = 1854 G1RegionToSpaceMapper::create_mapper(g1_rs, 1855 g1_rs.size(), 1856 page_size, 1857 HeapRegion::GrainBytes, 1858 1, 1859 mtJavaHeap); 1860 os::trace_page_sizes("Heap", 1861 collector_policy()->min_heap_byte_size(), 1862 max_byte_size, 1863 page_size, 1864 heap_rs.base(), 1865 heap_rs.size()); 1866 heap_storage->set_mapping_changed_listener(&_listener); 1867 1868 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps. 1869 G1RegionToSpaceMapper* bot_storage = 1870 create_aux_memory_mapper("Block Offset Table", 1871 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize), 1872 G1BlockOffsetTable::heap_map_factor()); 1873 1874 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize)); 1875 G1RegionToSpaceMapper* cardtable_storage = 1876 create_aux_memory_mapper("Card Table", 1877 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize), 1878 G1SATBCardTableLoggingModRefBS::heap_map_factor()); 1879 1880 G1RegionToSpaceMapper* card_counts_storage = 1881 create_aux_memory_mapper("Card Counts Table", 1882 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize), 1883 G1CardCounts::heap_map_factor()); 1884 1885 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size()); 1886 G1RegionToSpaceMapper* prev_bitmap_storage = 1887 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1888 G1RegionToSpaceMapper* next_bitmap_storage = 1889 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1890 1891 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage); 1892 g1_barrier_set()->initialize(cardtable_storage); 1893 // Do later initialization work for concurrent refinement. 1894 _hot_card_cache->initialize(card_counts_storage); 1895 1896 // 6843694 - ensure that the maximum region index can fit 1897 // in the remembered set structures. 1898 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; 1899 guarantee((max_regions() - 1) <= max_region_idx, "too many regions"); 1900 1901 g1_rem_set()->initialize(max_capacity(), max_regions()); 1902 1903 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; 1904 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); 1905 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region, 1906 "too many cards per region"); 1907 1908 FreeRegionList::set_unrealistically_long_length(max_regions() + 1); 1909 1910 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage); 1911 1912 { 1913 HeapWord* start = _hrm.reserved().start(); 1914 HeapWord* end = _hrm.reserved().end(); 1915 size_t granularity = HeapRegion::GrainBytes; 1916 1917 _in_cset_fast_test.initialize(start, end, granularity); 1918 _humongous_reclaim_candidates.initialize(start, end, granularity); 1919 } 1920 1921 // Create the G1ConcurrentMark data structure and thread. 1922 // (Must do this late, so that "max_regions" is defined.) 1923 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage); 1924 if (_cm == NULL || !_cm->completed_initialization()) { 1925 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark"); 1926 return JNI_ENOMEM; 1927 } 1928 _cmThread = _cm->cmThread(); 1929 1930 // Now expand into the initial heap size. 1931 if (!expand(init_byte_size, _workers)) { 1932 vm_shutdown_during_initialization("Failed to allocate initial heap."); 1933 return JNI_ENOMEM; 1934 } 1935 1936 // Perform any initialization actions delegated to the policy. 1937 g1_policy()->init(this, &_collection_set); 1938 1939 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon, 1940 SATB_Q_FL_lock, 1941 G1SATBProcessCompletedThreshold, 1942 Shared_SATB_Q_lock); 1943 1944 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl, 1945 DirtyCardQ_CBL_mon, 1946 DirtyCardQ_FL_lock, 1947 (int)concurrent_g1_refine()->yellow_zone(), 1948 (int)concurrent_g1_refine()->red_zone(), 1949 Shared_DirtyCardQ_lock, 1950 NULL, // fl_owner 1951 true); // init_free_ids 1952 1953 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code 1954 DirtyCardQ_CBL_mon, 1955 DirtyCardQ_FL_lock, 1956 -1, // never trigger processing 1957 -1, // no limit on length 1958 Shared_DirtyCardQ_lock, 1959 &JavaThread::dirty_card_queue_set()); 1960 1961 // Here we allocate the dummy HeapRegion that is required by the 1962 // G1AllocRegion class. 1963 HeapRegion* dummy_region = _hrm.get_dummy_region(); 1964 1965 // We'll re-use the same region whether the alloc region will 1966 // require BOT updates or not and, if it doesn't, then a non-young 1967 // region will complain that it cannot support allocations without 1968 // BOT updates. So we'll tag the dummy region as eden to avoid that. 1969 dummy_region->set_eden(); 1970 // Make sure it's full. 1971 dummy_region->set_top(dummy_region->end()); 1972 G1AllocRegion::setup(this, dummy_region); 1973 1974 _allocator->init_mutator_alloc_region(); 1975 1976 // Do create of the monitoring and management support so that 1977 // values in the heap have been properly initialized. 1978 _g1mm = new G1MonitoringSupport(this); 1979 1980 G1StringDedup::initialize(); 1981 1982 _preserved_marks_set.init(ParallelGCThreads); 1983 1984 _collection_set.initialize(max_regions()); 1985 1986 return JNI_OK; 1987 } 1988 1989 void G1CollectedHeap::stop() { 1990 // Stop all concurrent threads. We do this to make sure these threads 1991 // do not continue to execute and access resources (e.g. logging) 1992 // that are destroyed during shutdown. 1993 _cg1r->stop(); 1994 _cmThread->stop(); 1995 if (G1StringDedup::is_enabled()) { 1996 G1StringDedup::stop(); 1997 } 1998 } 1999 2000 size_t G1CollectedHeap::conservative_max_heap_alignment() { 2001 return HeapRegion::max_region_size(); 2002 } 2003 2004 void G1CollectedHeap::post_initialize() { 2005 ref_processing_init(); 2006 } 2007 2008 void G1CollectedHeap::ref_processing_init() { 2009 // Reference processing in G1 currently works as follows: 2010 // 2011 // * There are two reference processor instances. One is 2012 // used to record and process discovered references 2013 // during concurrent marking; the other is used to 2014 // record and process references during STW pauses 2015 // (both full and incremental). 2016 // * Both ref processors need to 'span' the entire heap as 2017 // the regions in the collection set may be dotted around. 2018 // 2019 // * For the concurrent marking ref processor: 2020 // * Reference discovery is enabled at initial marking. 2021 // * Reference discovery is disabled and the discovered 2022 // references processed etc during remarking. 2023 // * Reference discovery is MT (see below). 2024 // * Reference discovery requires a barrier (see below). 2025 // * Reference processing may or may not be MT 2026 // (depending on the value of ParallelRefProcEnabled 2027 // and ParallelGCThreads). 2028 // * A full GC disables reference discovery by the CM 2029 // ref processor and abandons any entries on it's 2030 // discovered lists. 2031 // 2032 // * For the STW processor: 2033 // * Non MT discovery is enabled at the start of a full GC. 2034 // * Processing and enqueueing during a full GC is non-MT. 2035 // * During a full GC, references are processed after marking. 2036 // 2037 // * Discovery (may or may not be MT) is enabled at the start 2038 // of an incremental evacuation pause. 2039 // * References are processed near the end of a STW evacuation pause. 2040 // * For both types of GC: 2041 // * Discovery is atomic - i.e. not concurrent. 2042 // * Reference discovery will not need a barrier. 2043 2044 MemRegion mr = reserved_region(); 2045 2046 // Concurrent Mark ref processor 2047 _ref_processor_cm = 2048 new ReferenceProcessor(mr, // span 2049 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2050 // mt processing 2051 ParallelGCThreads, 2052 // degree of mt processing 2053 (ParallelGCThreads > 1) || (ConcGCThreads > 1), 2054 // mt discovery 2055 MAX2(ParallelGCThreads, ConcGCThreads), 2056 // degree of mt discovery 2057 false, 2058 // Reference discovery is not atomic 2059 &_is_alive_closure_cm); 2060 // is alive closure 2061 // (for efficiency/performance) 2062 2063 // STW ref processor 2064 _ref_processor_stw = 2065 new ReferenceProcessor(mr, // span 2066 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2067 // mt processing 2068 ParallelGCThreads, 2069 // degree of mt processing 2070 (ParallelGCThreads > 1), 2071 // mt discovery 2072 ParallelGCThreads, 2073 // degree of mt discovery 2074 true, 2075 // Reference discovery is atomic 2076 &_is_alive_closure_stw); 2077 // is alive closure 2078 // (for efficiency/performance) 2079 } 2080 2081 CollectorPolicy* G1CollectedHeap::collector_policy() const { 2082 return _collector_policy; 2083 } 2084 2085 size_t G1CollectedHeap::capacity() const { 2086 return _hrm.length() * HeapRegion::GrainBytes; 2087 } 2088 2089 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) { 2090 hr->reset_gc_time_stamp(); 2091 } 2092 2093 #ifndef PRODUCT 2094 2095 class CheckGCTimeStampsHRClosure : public HeapRegionClosure { 2096 private: 2097 unsigned _gc_time_stamp; 2098 bool _failures; 2099 2100 public: 2101 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) : 2102 _gc_time_stamp(gc_time_stamp), _failures(false) { } 2103 2104 virtual bool doHeapRegion(HeapRegion* hr) { 2105 unsigned region_gc_time_stamp = hr->get_gc_time_stamp(); 2106 if (_gc_time_stamp != region_gc_time_stamp) { 2107 log_error(gc, verify)("Region " HR_FORMAT " has GC time stamp = %d, expected %d", HR_FORMAT_PARAMS(hr), 2108 region_gc_time_stamp, _gc_time_stamp); 2109 _failures = true; 2110 } 2111 return false; 2112 } 2113 2114 bool failures() { return _failures; } 2115 }; 2116 2117 void G1CollectedHeap::check_gc_time_stamps() { 2118 CheckGCTimeStampsHRClosure cl(_gc_time_stamp); 2119 heap_region_iterate(&cl); 2120 guarantee(!cl.failures(), "all GC time stamps should have been reset"); 2121 } 2122 #endif // PRODUCT 2123 2124 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) { 2125 _hot_card_cache->drain(cl, worker_i); 2126 } 2127 2128 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) { 2129 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 2130 size_t n_completed_buffers = 0; 2131 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) { 2132 n_completed_buffers++; 2133 } 2134 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers); 2135 dcqs.clear_n_completed_buffers(); 2136 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!"); 2137 } 2138 2139 // Computes the sum of the storage used by the various regions. 2140 size_t G1CollectedHeap::used() const { 2141 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions(); 2142 if (_archive_allocator != NULL) { 2143 result += _archive_allocator->used(); 2144 } 2145 return result; 2146 } 2147 2148 size_t G1CollectedHeap::used_unlocked() const { 2149 return _summary_bytes_used; 2150 } 2151 2152 class SumUsedClosure: public HeapRegionClosure { 2153 size_t _used; 2154 public: 2155 SumUsedClosure() : _used(0) {} 2156 bool doHeapRegion(HeapRegion* r) { 2157 _used += r->used(); 2158 return false; 2159 } 2160 size_t result() { return _used; } 2161 }; 2162 2163 size_t G1CollectedHeap::recalculate_used() const { 2164 double recalculate_used_start = os::elapsedTime(); 2165 2166 SumUsedClosure blk; 2167 heap_region_iterate(&blk); 2168 2169 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0); 2170 return blk.result(); 2171 } 2172 2173 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) { 2174 switch (cause) { 2175 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent; 2176 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent; 2177 case GCCause::_update_allocation_context_stats_inc: return true; 2178 case GCCause::_wb_conc_mark: return true; 2179 default : return false; 2180 } 2181 } 2182 2183 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 2184 switch (cause) { 2185 case GCCause::_gc_locker: return GCLockerInvokesConcurrent; 2186 case GCCause::_g1_humongous_allocation: return true; 2187 default: return is_user_requested_concurrent_full_gc(cause); 2188 } 2189 } 2190 2191 #ifndef PRODUCT 2192 void G1CollectedHeap::allocate_dummy_regions() { 2193 // Let's fill up most of the region 2194 size_t word_size = HeapRegion::GrainWords - 1024; 2195 // And as a result the region we'll allocate will be humongous. 2196 guarantee(is_humongous(word_size), "sanity"); 2197 2198 // _filler_array_max_size is set to humongous object threshold 2199 // but temporarily change it to use CollectedHeap::fill_with_object(). 2200 SizeTFlagSetting fs(_filler_array_max_size, word_size); 2201 2202 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) { 2203 // Let's use the existing mechanism for the allocation 2204 HeapWord* dummy_obj = humongous_obj_allocate(word_size, 2205 AllocationContext::system()); 2206 if (dummy_obj != NULL) { 2207 MemRegion mr(dummy_obj, word_size); 2208 CollectedHeap::fill_with_object(mr); 2209 } else { 2210 // If we can't allocate once, we probably cannot allocate 2211 // again. Let's get out of the loop. 2212 break; 2213 } 2214 } 2215 } 2216 #endif // !PRODUCT 2217 2218 void G1CollectedHeap::increment_old_marking_cycles_started() { 2219 assert(_old_marking_cycles_started == _old_marking_cycles_completed || 2220 _old_marking_cycles_started == _old_marking_cycles_completed + 1, 2221 "Wrong marking cycle count (started: %d, completed: %d)", 2222 _old_marking_cycles_started, _old_marking_cycles_completed); 2223 2224 _old_marking_cycles_started++; 2225 } 2226 2227 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) { 2228 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 2229 2230 // We assume that if concurrent == true, then the caller is a 2231 // concurrent thread that was joined the Suspendible Thread 2232 // Set. If there's ever a cheap way to check this, we should add an 2233 // assert here. 2234 2235 // Given that this method is called at the end of a Full GC or of a 2236 // concurrent cycle, and those can be nested (i.e., a Full GC can 2237 // interrupt a concurrent cycle), the number of full collections 2238 // completed should be either one (in the case where there was no 2239 // nesting) or two (when a Full GC interrupted a concurrent cycle) 2240 // behind the number of full collections started. 2241 2242 // This is the case for the inner caller, i.e. a Full GC. 2243 assert(concurrent || 2244 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || 2245 (_old_marking_cycles_started == _old_marking_cycles_completed + 2), 2246 "for inner caller (Full GC): _old_marking_cycles_started = %u " 2247 "is inconsistent with _old_marking_cycles_completed = %u", 2248 _old_marking_cycles_started, _old_marking_cycles_completed); 2249 2250 // This is the case for the outer caller, i.e. the concurrent cycle. 2251 assert(!concurrent || 2252 (_old_marking_cycles_started == _old_marking_cycles_completed + 1), 2253 "for outer caller (concurrent cycle): " 2254 "_old_marking_cycles_started = %u " 2255 "is inconsistent with _old_marking_cycles_completed = %u", 2256 _old_marking_cycles_started, _old_marking_cycles_completed); 2257 2258 _old_marking_cycles_completed += 1; 2259 2260 // We need to clear the "in_progress" flag in the CM thread before 2261 // we wake up any waiters (especially when ExplicitInvokesConcurrent 2262 // is set) so that if a waiter requests another System.gc() it doesn't 2263 // incorrectly see that a marking cycle is still in progress. 2264 if (concurrent) { 2265 _cmThread->set_idle(); 2266 } 2267 2268 // This notify_all() will ensure that a thread that called 2269 // System.gc() with (with ExplicitGCInvokesConcurrent set or not) 2270 // and it's waiting for a full GC to finish will be woken up. It is 2271 // waiting in VM_G1IncCollectionPause::doit_epilogue(). 2272 FullGCCount_lock->notify_all(); 2273 } 2274 2275 void G1CollectedHeap::collect(GCCause::Cause cause) { 2276 assert_heap_not_locked(); 2277 2278 uint gc_count_before; 2279 uint old_marking_count_before; 2280 uint full_gc_count_before; 2281 bool retry_gc; 2282 2283 do { 2284 retry_gc = false; 2285 2286 { 2287 MutexLocker ml(Heap_lock); 2288 2289 // Read the GC count while holding the Heap_lock 2290 gc_count_before = total_collections(); 2291 full_gc_count_before = total_full_collections(); 2292 old_marking_count_before = _old_marking_cycles_started; 2293 } 2294 2295 if (should_do_concurrent_full_gc(cause)) { 2296 // Schedule an initial-mark evacuation pause that will start a 2297 // concurrent cycle. We're setting word_size to 0 which means that 2298 // we are not requesting a post-GC allocation. 2299 VM_G1IncCollectionPause op(gc_count_before, 2300 0, /* word_size */ 2301 true, /* should_initiate_conc_mark */ 2302 g1_policy()->max_pause_time_ms(), 2303 cause); 2304 op.set_allocation_context(AllocationContext::current()); 2305 2306 VMThread::execute(&op); 2307 if (!op.pause_succeeded()) { 2308 if (old_marking_count_before == _old_marking_cycles_started) { 2309 retry_gc = op.should_retry_gc(); 2310 } else { 2311 // A Full GC happened while we were trying to schedule the 2312 // initial-mark GC. No point in starting a new cycle given 2313 // that the whole heap was collected anyway. 2314 } 2315 2316 if (retry_gc) { 2317 if (GCLocker::is_active_and_needs_gc()) { 2318 GCLocker::stall_until_clear(); 2319 } 2320 } 2321 } 2322 } else { 2323 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc 2324 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { 2325 2326 // Schedule a standard evacuation pause. We're setting word_size 2327 // to 0 which means that we are not requesting a post-GC allocation. 2328 VM_G1IncCollectionPause op(gc_count_before, 2329 0, /* word_size */ 2330 false, /* should_initiate_conc_mark */ 2331 g1_policy()->max_pause_time_ms(), 2332 cause); 2333 VMThread::execute(&op); 2334 } else { 2335 // Schedule a Full GC. 2336 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause); 2337 VMThread::execute(&op); 2338 } 2339 } 2340 } while (retry_gc); 2341 } 2342 2343 bool G1CollectedHeap::is_in(const void* p) const { 2344 if (_hrm.reserved().contains(p)) { 2345 // Given that we know that p is in the reserved space, 2346 // heap_region_containing() should successfully 2347 // return the containing region. 2348 HeapRegion* hr = heap_region_containing(p); 2349 return hr->is_in(p); 2350 } else { 2351 return false; 2352 } 2353 } 2354 2355 #ifdef ASSERT 2356 bool G1CollectedHeap::is_in_exact(const void* p) const { 2357 bool contains = reserved_region().contains(p); 2358 bool available = _hrm.is_available(addr_to_region((HeapWord*)p)); 2359 if (contains && available) { 2360 return true; 2361 } else { 2362 return false; 2363 } 2364 } 2365 #endif 2366 2367 // Iteration functions. 2368 2369 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion. 2370 2371 class IterateOopClosureRegionClosure: public HeapRegionClosure { 2372 ExtendedOopClosure* _cl; 2373 public: 2374 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {} 2375 bool doHeapRegion(HeapRegion* r) { 2376 if (!r->is_continues_humongous()) { 2377 r->oop_iterate(_cl); 2378 } 2379 return false; 2380 } 2381 }; 2382 2383 // Iterates an ObjectClosure over all objects within a HeapRegion. 2384 2385 class IterateObjectClosureRegionClosure: public HeapRegionClosure { 2386 ObjectClosure* _cl; 2387 public: 2388 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} 2389 bool doHeapRegion(HeapRegion* r) { 2390 if (!r->is_continues_humongous()) { 2391 r->object_iterate(_cl); 2392 } 2393 return false; 2394 } 2395 }; 2396 2397 void G1CollectedHeap::object_iterate(ObjectClosure* cl) { 2398 IterateObjectClosureRegionClosure blk(cl); 2399 heap_region_iterate(&blk); 2400 } 2401 2402 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { 2403 _hrm.iterate(cl); 2404 } 2405 2406 void 2407 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl, 2408 uint worker_id, 2409 HeapRegionClaimer *hrclaimer, 2410 bool concurrent) const { 2411 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent); 2412 } 2413 2414 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) { 2415 _collection_set.iterate(cl); 2416 } 2417 2418 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) { 2419 _collection_set.iterate_from(cl, worker_id, workers()->active_workers()); 2420 } 2421 2422 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const { 2423 HeapRegion* result = _hrm.next_region_in_heap(from); 2424 while (result != NULL && result->is_pinned()) { 2425 result = _hrm.next_region_in_heap(result); 2426 } 2427 return result; 2428 } 2429 2430 HeapWord* G1CollectedHeap::block_start(const void* addr) const { 2431 HeapRegion* hr = heap_region_containing(addr); 2432 return hr->block_start(addr); 2433 } 2434 2435 size_t G1CollectedHeap::block_size(const HeapWord* addr) const { 2436 HeapRegion* hr = heap_region_containing(addr); 2437 return hr->block_size(addr); 2438 } 2439 2440 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { 2441 HeapRegion* hr = heap_region_containing(addr); 2442 return hr->block_is_obj(addr); 2443 } 2444 2445 bool G1CollectedHeap::supports_tlab_allocation() const { 2446 return true; 2447 } 2448 2449 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { 2450 return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes; 2451 } 2452 2453 size_t G1CollectedHeap::tlab_used(Thread* ignored) const { 2454 return _eden.length() * HeapRegion::GrainBytes; 2455 } 2456 2457 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size 2458 // must be equal to the humongous object limit. 2459 size_t G1CollectedHeap::max_tlab_size() const { 2460 return align_size_down(_humongous_object_threshold_in_words, MinObjAlignment); 2461 } 2462 2463 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { 2464 AllocationContext_t context = AllocationContext::current(); 2465 return _allocator->unsafe_max_tlab_alloc(context); 2466 } 2467 2468 size_t G1CollectedHeap::max_capacity() const { 2469 return _hrm.reserved().byte_size(); 2470 } 2471 2472 jlong G1CollectedHeap::millis_since_last_gc() { 2473 // See the notes in GenCollectedHeap::millis_since_last_gc() 2474 // for more information about the implementation. 2475 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) - 2476 _g1_policy->collection_pause_end_millis(); 2477 if (ret_val < 0) { 2478 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT 2479 ". returning zero instead.", ret_val); 2480 return 0; 2481 } 2482 return ret_val; 2483 } 2484 2485 void G1CollectedHeap::prepare_for_verify() { 2486 _verifier->prepare_for_verify(); 2487 } 2488 2489 void G1CollectedHeap::verify(VerifyOption vo) { 2490 _verifier->verify(vo); 2491 } 2492 2493 class PrintRegionClosure: public HeapRegionClosure { 2494 outputStream* _st; 2495 public: 2496 PrintRegionClosure(outputStream* st) : _st(st) {} 2497 bool doHeapRegion(HeapRegion* r) { 2498 r->print_on(_st); 2499 return false; 2500 } 2501 }; 2502 2503 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2504 const HeapRegion* hr, 2505 const VerifyOption vo) const { 2506 switch (vo) { 2507 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); 2508 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); 2509 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked() && !hr->is_archive(); 2510 default: ShouldNotReachHere(); 2511 } 2512 return false; // keep some compilers happy 2513 } 2514 2515 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2516 const VerifyOption vo) const { 2517 switch (vo) { 2518 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); 2519 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); 2520 case VerifyOption_G1UseMarkWord: { 2521 HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj); 2522 return !obj->is_gc_marked() && !hr->is_archive(); 2523 } 2524 default: ShouldNotReachHere(); 2525 } 2526 return false; // keep some compilers happy 2527 } 2528 2529 void G1CollectedHeap::print_heap_regions() const { 2530 Log(gc, heap, region) log; 2531 if (log.is_trace()) { 2532 ResourceMark rm; 2533 print_regions_on(log.trace_stream()); 2534 } 2535 } 2536 2537 void G1CollectedHeap::print_on(outputStream* st) const { 2538 st->print(" %-20s", "garbage-first heap"); 2539 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 2540 capacity()/K, used_unlocked()/K); 2541 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")", 2542 p2i(_hrm.reserved().start()), 2543 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords), 2544 p2i(_hrm.reserved().end())); 2545 st->cr(); 2546 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); 2547 uint young_regions = young_regions_count(); 2548 st->print("%u young (" SIZE_FORMAT "K), ", young_regions, 2549 (size_t) young_regions * HeapRegion::GrainBytes / K); 2550 uint survivor_regions = survivor_regions_count(); 2551 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, 2552 (size_t) survivor_regions * HeapRegion::GrainBytes / K); 2553 st->cr(); 2554 MetaspaceAux::print_on(st); 2555 } 2556 2557 void G1CollectedHeap::print_regions_on(outputStream* st) const { 2558 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, " 2559 "HS=humongous(starts), HC=humongous(continues), " 2560 "CS=collection set, F=free, A=archive, TS=gc time stamp, " 2561 "AC=allocation context, " 2562 "TAMS=top-at-mark-start (previous, next)"); 2563 PrintRegionClosure blk(st); 2564 heap_region_iterate(&blk); 2565 } 2566 2567 void G1CollectedHeap::print_extended_on(outputStream* st) const { 2568 print_on(st); 2569 2570 // Print the per-region information. 2571 print_regions_on(st); 2572 } 2573 2574 void G1CollectedHeap::print_on_error(outputStream* st) const { 2575 this->CollectedHeap::print_on_error(st); 2576 2577 if (_cm != NULL) { 2578 st->cr(); 2579 _cm->print_on_error(st); 2580 } 2581 } 2582 2583 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const { 2584 workers()->print_worker_threads_on(st); 2585 _cmThread->print_on(st); 2586 st->cr(); 2587 _cm->print_worker_threads_on(st); 2588 _cg1r->print_worker_threads_on(st); // also prints the sample thread 2589 if (G1StringDedup::is_enabled()) { 2590 G1StringDedup::print_worker_threads_on(st); 2591 } 2592 } 2593 2594 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { 2595 workers()->threads_do(tc); 2596 tc->do_thread(_cmThread); 2597 _cm->threads_do(tc); 2598 _cg1r->threads_do(tc); // also iterates over the sample thread 2599 if (G1StringDedup::is_enabled()) { 2600 G1StringDedup::threads_do(tc); 2601 } 2602 } 2603 2604 void G1CollectedHeap::print_tracing_info() const { 2605 g1_rem_set()->print_summary_info(); 2606 concurrent_mark()->print_summary_info(); 2607 } 2608 2609 #ifndef PRODUCT 2610 // Helpful for debugging RSet issues. 2611 2612 class PrintRSetsClosure : public HeapRegionClosure { 2613 private: 2614 const char* _msg; 2615 size_t _occupied_sum; 2616 2617 public: 2618 bool doHeapRegion(HeapRegion* r) { 2619 HeapRegionRemSet* hrrs = r->rem_set(); 2620 size_t occupied = hrrs->occupied(); 2621 _occupied_sum += occupied; 2622 2623 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r)); 2624 if (occupied == 0) { 2625 tty->print_cr(" RSet is empty"); 2626 } else { 2627 hrrs->print(); 2628 } 2629 tty->print_cr("----------"); 2630 return false; 2631 } 2632 2633 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { 2634 tty->cr(); 2635 tty->print_cr("========================================"); 2636 tty->print_cr("%s", msg); 2637 tty->cr(); 2638 } 2639 2640 ~PrintRSetsClosure() { 2641 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum); 2642 tty->print_cr("========================================"); 2643 tty->cr(); 2644 } 2645 }; 2646 2647 void G1CollectedHeap::print_cset_rsets() { 2648 PrintRSetsClosure cl("Printing CSet RSets"); 2649 collection_set_iterate(&cl); 2650 } 2651 2652 void G1CollectedHeap::print_all_rsets() { 2653 PrintRSetsClosure cl("Printing All RSets");; 2654 heap_region_iterate(&cl); 2655 } 2656 #endif // PRODUCT 2657 2658 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() { 2659 2660 size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes; 2661 size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes; 2662 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked(); 2663 2664 size_t eden_capacity_bytes = 2665 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes; 2666 2667 VirtualSpaceSummary heap_summary = create_heap_space_summary(); 2668 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes, 2669 eden_capacity_bytes, survivor_used_bytes, num_regions()); 2670 } 2671 2672 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) { 2673 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(), 2674 stats->unused(), stats->used(), stats->region_end_waste(), 2675 stats->regions_filled(), stats->direct_allocated(), 2676 stats->failure_used(), stats->failure_waste()); 2677 } 2678 2679 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) { 2680 const G1HeapSummary& heap_summary = create_g1_heap_summary(); 2681 gc_tracer->report_gc_heap_summary(when, heap_summary); 2682 2683 const MetaspaceSummary& metaspace_summary = create_metaspace_summary(); 2684 gc_tracer->report_metaspace_summary(when, metaspace_summary); 2685 } 2686 2687 G1CollectedHeap* G1CollectedHeap::heap() { 2688 CollectedHeap* heap = Universe::heap(); 2689 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()"); 2690 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap"); 2691 return (G1CollectedHeap*)heap; 2692 } 2693 2694 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) { 2695 // always_do_update_barrier = false; 2696 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 2697 // Fill TLAB's and such 2698 accumulate_statistics_all_tlabs(); 2699 ensure_parsability(true); 2700 2701 g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections()); 2702 } 2703 2704 void G1CollectedHeap::gc_epilogue(bool full) { 2705 // we are at the end of the GC. Total collections has already been increased. 2706 g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1); 2707 2708 // FIXME: what is this about? 2709 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" 2710 // is set. 2711 #if defined(COMPILER2) || INCLUDE_JVMCI 2712 assert(DerivedPointerTable::is_empty(), "derived pointer present"); 2713 #endif 2714 // always_do_update_barrier = true; 2715 2716 resize_all_tlabs(); 2717 allocation_context_stats().update(full); 2718 2719 // We have just completed a GC. Update the soft reference 2720 // policy with the new heap occupancy 2721 Universe::update_heap_info_at_gc(); 2722 } 2723 2724 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, 2725 uint gc_count_before, 2726 bool* succeeded, 2727 GCCause::Cause gc_cause) { 2728 assert_heap_not_locked_and_not_at_safepoint(); 2729 VM_G1IncCollectionPause op(gc_count_before, 2730 word_size, 2731 false, /* should_initiate_conc_mark */ 2732 g1_policy()->max_pause_time_ms(), 2733 gc_cause); 2734 2735 op.set_allocation_context(AllocationContext::current()); 2736 VMThread::execute(&op); 2737 2738 HeapWord* result = op.result(); 2739 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded(); 2740 assert(result == NULL || ret_succeeded, 2741 "the result should be NULL if the VM did not succeed"); 2742 *succeeded = ret_succeeded; 2743 2744 assert_heap_not_locked(); 2745 return result; 2746 } 2747 2748 void 2749 G1CollectedHeap::doConcurrentMark() { 2750 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); 2751 if (!_cmThread->in_progress()) { 2752 _cmThread->set_started(); 2753 CGC_lock->notify(); 2754 } 2755 } 2756 2757 size_t G1CollectedHeap::pending_card_num() { 2758 size_t extra_cards = 0; 2759 JavaThread *curr = Threads::first(); 2760 while (curr != NULL) { 2761 DirtyCardQueue& dcq = curr->dirty_card_queue(); 2762 extra_cards += dcq.size(); 2763 curr = curr->next(); 2764 } 2765 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 2766 size_t buffer_size = dcqs.buffer_size(); 2767 size_t buffer_num = dcqs.completed_buffers_num(); 2768 2769 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes 2770 // in bytes - not the number of 'entries'. We need to convert 2771 // into a number of cards. 2772 return (buffer_size * buffer_num + extra_cards) / oopSize; 2773 } 2774 2775 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure { 2776 private: 2777 size_t _total_humongous; 2778 size_t _candidate_humongous; 2779 2780 DirtyCardQueue _dcq; 2781 2782 // We don't nominate objects with many remembered set entries, on 2783 // the assumption that such objects are likely still live. 2784 bool is_remset_small(HeapRegion* region) const { 2785 HeapRegionRemSet* const rset = region->rem_set(); 2786 return G1EagerReclaimHumongousObjectsWithStaleRefs 2787 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) 2788 : rset->is_empty(); 2789 } 2790 2791 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const { 2792 assert(region->is_starts_humongous(), "Must start a humongous object"); 2793 2794 oop obj = oop(region->bottom()); 2795 2796 // Dead objects cannot be eager reclaim candidates. Due to class 2797 // unloading it is unsafe to query their classes so we return early. 2798 if (heap->is_obj_dead(obj, region)) { 2799 return false; 2800 } 2801 2802 // Candidate selection must satisfy the following constraints 2803 // while concurrent marking is in progress: 2804 // 2805 // * In order to maintain SATB invariants, an object must not be 2806 // reclaimed if it was allocated before the start of marking and 2807 // has not had its references scanned. Such an object must have 2808 // its references (including type metadata) scanned to ensure no 2809 // live objects are missed by the marking process. Objects 2810 // allocated after the start of concurrent marking don't need to 2811 // be scanned. 2812 // 2813 // * An object must not be reclaimed if it is on the concurrent 2814 // mark stack. Objects allocated after the start of concurrent 2815 // marking are never pushed on the mark stack. 2816 // 2817 // Nominating only objects allocated after the start of concurrent 2818 // marking is sufficient to meet both constraints. This may miss 2819 // some objects that satisfy the constraints, but the marking data 2820 // structures don't support efficiently performing the needed 2821 // additional tests or scrubbing of the mark stack. 2822 // 2823 // However, we presently only nominate is_typeArray() objects. 2824 // A humongous object containing references induces remembered 2825 // set entries on other regions. In order to reclaim such an 2826 // object, those remembered sets would need to be cleaned up. 2827 // 2828 // We also treat is_typeArray() objects specially, allowing them 2829 // to be reclaimed even if allocated before the start of 2830 // concurrent mark. For this we rely on mark stack insertion to 2831 // exclude is_typeArray() objects, preventing reclaiming an object 2832 // that is in the mark stack. We also rely on the metadata for 2833 // such objects to be built-in and so ensured to be kept live. 2834 // Frequent allocation and drop of large binary blobs is an 2835 // important use case for eager reclaim, and this special handling 2836 // may reduce needed headroom. 2837 2838 return obj->is_typeArray() && is_remset_small(region); 2839 } 2840 2841 public: 2842 RegisterHumongousWithInCSetFastTestClosure() 2843 : _total_humongous(0), 2844 _candidate_humongous(0), 2845 _dcq(&JavaThread::dirty_card_queue_set()) { 2846 } 2847 2848 virtual bool doHeapRegion(HeapRegion* r) { 2849 if (!r->is_starts_humongous()) { 2850 return false; 2851 } 2852 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 2853 2854 bool is_candidate = humongous_region_is_candidate(g1h, r); 2855 uint rindex = r->hrm_index(); 2856 g1h->set_humongous_reclaim_candidate(rindex, is_candidate); 2857 if (is_candidate) { 2858 _candidate_humongous++; 2859 g1h->register_humongous_region_with_cset(rindex); 2860 // Is_candidate already filters out humongous object with large remembered sets. 2861 // If we have a humongous object with a few remembered sets, we simply flush these 2862 // remembered set entries into the DCQS. That will result in automatic 2863 // re-evaluation of their remembered set entries during the following evacuation 2864 // phase. 2865 if (!r->rem_set()->is_empty()) { 2866 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries), 2867 "Found a not-small remembered set here. This is inconsistent with previous assumptions."); 2868 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set(); 2869 HeapRegionRemSetIterator hrrs(r->rem_set()); 2870 size_t card_index; 2871 while (hrrs.has_next(card_index)) { 2872 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index); 2873 // The remembered set might contain references to already freed 2874 // regions. Filter out such entries to avoid failing card table 2875 // verification. 2876 if (g1h->is_in_closed_subset(bs->addr_for(card_ptr))) { 2877 if (*card_ptr != CardTableModRefBS::dirty_card_val()) { 2878 *card_ptr = CardTableModRefBS::dirty_card_val(); 2879 _dcq.enqueue(card_ptr); 2880 } 2881 } 2882 } 2883 assert(hrrs.n_yielded() == r->rem_set()->occupied(), 2884 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries", 2885 hrrs.n_yielded(), r->rem_set()->occupied()); 2886 r->rem_set()->clear_locked(); 2887 } 2888 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty."); 2889 } 2890 _total_humongous++; 2891 2892 return false; 2893 } 2894 2895 size_t total_humongous() const { return _total_humongous; } 2896 size_t candidate_humongous() const { return _candidate_humongous; } 2897 2898 void flush_rem_set_entries() { _dcq.flush(); } 2899 }; 2900 2901 void G1CollectedHeap::register_humongous_regions_with_cset() { 2902 if (!G1EagerReclaimHumongousObjects) { 2903 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0); 2904 return; 2905 } 2906 double time = os::elapsed_counter(); 2907 2908 // Collect reclaim candidate information and register candidates with cset. 2909 RegisterHumongousWithInCSetFastTestClosure cl; 2910 heap_region_iterate(&cl); 2911 2912 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0; 2913 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time, 2914 cl.total_humongous(), 2915 cl.candidate_humongous()); 2916 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0; 2917 2918 // Finally flush all remembered set entries to re-check into the global DCQS. 2919 cl.flush_rem_set_entries(); 2920 } 2921 2922 class VerifyRegionRemSetClosure : public HeapRegionClosure { 2923 public: 2924 bool doHeapRegion(HeapRegion* hr) { 2925 if (!hr->is_archive() && !hr->is_continues_humongous()) { 2926 hr->verify_rem_set(); 2927 } 2928 return false; 2929 } 2930 }; 2931 2932 uint G1CollectedHeap::num_task_queues() const { 2933 return _task_queues->size(); 2934 } 2935 2936 #if TASKQUEUE_STATS 2937 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) { 2938 st->print_raw_cr("GC Task Stats"); 2939 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); 2940 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); 2941 } 2942 2943 void G1CollectedHeap::print_taskqueue_stats() const { 2944 if (!log_is_enabled(Trace, gc, task, stats)) { 2945 return; 2946 } 2947 Log(gc, task, stats) log; 2948 ResourceMark rm; 2949 outputStream* st = log.trace_stream(); 2950 2951 print_taskqueue_stats_hdr(st); 2952 2953 TaskQueueStats totals; 2954 const uint n = num_task_queues(); 2955 for (uint i = 0; i < n; ++i) { 2956 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr(); 2957 totals += task_queue(i)->stats; 2958 } 2959 st->print_raw("tot "); totals.print(st); st->cr(); 2960 2961 DEBUG_ONLY(totals.verify()); 2962 } 2963 2964 void G1CollectedHeap::reset_taskqueue_stats() { 2965 const uint n = num_task_queues(); 2966 for (uint i = 0; i < n; ++i) { 2967 task_queue(i)->stats.reset(); 2968 } 2969 } 2970 #endif // TASKQUEUE_STATS 2971 2972 void G1CollectedHeap::wait_for_root_region_scanning() { 2973 double scan_wait_start = os::elapsedTime(); 2974 // We have to wait until the CM threads finish scanning the 2975 // root regions as it's the only way to ensure that all the 2976 // objects on them have been correctly scanned before we start 2977 // moving them during the GC. 2978 bool waited = _cm->root_regions()->wait_until_scan_finished(); 2979 double wait_time_ms = 0.0; 2980 if (waited) { 2981 double scan_wait_end = os::elapsedTime(); 2982 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0; 2983 } 2984 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms); 2985 } 2986 2987 class G1PrintCollectionSetClosure : public HeapRegionClosure { 2988 private: 2989 G1HRPrinter* _hr_printer; 2990 public: 2991 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { } 2992 2993 virtual bool doHeapRegion(HeapRegion* r) { 2994 _hr_printer->cset(r); 2995 return false; 2996 } 2997 }; 2998 2999 bool 3000 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { 3001 assert_at_safepoint(true /* should_be_vm_thread */); 3002 guarantee(!is_gc_active(), "collection is not reentrant"); 3003 3004 if (GCLocker::check_active_before_gc()) { 3005 return false; 3006 } 3007 3008 _gc_timer_stw->register_gc_start(); 3009 3010 GCIdMark gc_id_mark; 3011 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start()); 3012 3013 SvcGCMarker sgcm(SvcGCMarker::MINOR); 3014 ResourceMark rm; 3015 3016 g1_policy()->note_gc_start(); 3017 3018 wait_for_root_region_scanning(); 3019 3020 print_heap_before_gc(); 3021 print_heap_regions(); 3022 trace_heap_before_gc(_gc_tracer_stw); 3023 3024 _verifier->verify_region_sets_optional(); 3025 _verifier->verify_dirty_young_regions(); 3026 3027 // We should not be doing initial mark unless the conc mark thread is running 3028 if (!_cmThread->should_terminate()) { 3029 // This call will decide whether this pause is an initial-mark 3030 // pause. If it is, during_initial_mark_pause() will return true 3031 // for the duration of this pause. 3032 g1_policy()->decide_on_conc_mark_initiation(); 3033 } 3034 3035 // We do not allow initial-mark to be piggy-backed on a mixed GC. 3036 assert(!collector_state()->during_initial_mark_pause() || 3037 collector_state()->gcs_are_young(), "sanity"); 3038 3039 // We also do not allow mixed GCs during marking. 3040 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity"); 3041 3042 // Record whether this pause is an initial mark. When the current 3043 // thread has completed its logging output and it's safe to signal 3044 // the CM thread, the flag's value in the policy has been reset. 3045 bool should_start_conc_mark = collector_state()->during_initial_mark_pause(); 3046 3047 // Inner scope for scope based logging, timers, and stats collection 3048 { 3049 EvacuationInfo evacuation_info; 3050 3051 if (collector_state()->during_initial_mark_pause()) { 3052 // We are about to start a marking cycle, so we increment the 3053 // full collection counter. 3054 increment_old_marking_cycles_started(); 3055 _cm->gc_tracer_cm()->set_gc_cause(gc_cause()); 3056 } 3057 3058 _gc_tracer_stw->report_yc_type(collector_state()->yc_type()); 3059 3060 GCTraceCPUTime tcpu; 3061 3062 FormatBuffer<> gc_string("Pause "); 3063 if (collector_state()->during_initial_mark_pause()) { 3064 gc_string.append("Initial Mark"); 3065 } else if (collector_state()->gcs_are_young()) { 3066 gc_string.append("Young"); 3067 } else { 3068 gc_string.append("Mixed"); 3069 } 3070 GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true); 3071 3072 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 3073 workers()->active_workers(), 3074 Threads::number_of_non_daemon_threads()); 3075 workers()->update_active_workers(active_workers); 3076 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers()); 3077 3078 TraceCollectorStats tcs(g1mm()->incremental_collection_counters()); 3079 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause()); 3080 3081 // If the secondary_free_list is not empty, append it to the 3082 // free_list. No need to wait for the cleanup operation to finish; 3083 // the region allocation code will check the secondary_free_list 3084 // and wait if necessary. If the G1StressConcRegionFreeing flag is 3085 // set, skip this step so that the region allocation code has to 3086 // get entries from the secondary_free_list. 3087 if (!G1StressConcRegionFreeing) { 3088 append_secondary_free_list_if_not_empty_with_lock(); 3089 } 3090 3091 G1HeapTransition heap_transition(this); 3092 size_t heap_used_bytes_before_gc = used(); 3093 3094 // Don't dynamically change the number of GC threads this early. A value of 3095 // 0 is used to indicate serial work. When parallel work is done, 3096 // it will be set. 3097 3098 { // Call to jvmpi::post_class_unload_events must occur outside of active GC 3099 IsGCActiveMark x; 3100 3101 gc_prologue(false); 3102 increment_total_collections(false /* full gc */); 3103 increment_gc_time_stamp(); 3104 3105 if (VerifyRememberedSets) { 3106 log_info(gc, verify)("[Verifying RemSets before GC]"); 3107 VerifyRegionRemSetClosure v_cl; 3108 heap_region_iterate(&v_cl); 3109 } 3110 3111 _verifier->verify_before_gc(); 3112 3113 _verifier->check_bitmaps("GC Start"); 3114 3115 #if defined(COMPILER2) || INCLUDE_JVMCI 3116 DerivedPointerTable::clear(); 3117 #endif 3118 3119 // Please see comment in g1CollectedHeap.hpp and 3120 // G1CollectedHeap::ref_processing_init() to see how 3121 // reference processing currently works in G1. 3122 3123 // Enable discovery in the STW reference processor 3124 if (g1_policy()->should_process_references()) { 3125 ref_processor_stw()->enable_discovery(); 3126 } else { 3127 ref_processor_stw()->disable_discovery(); 3128 } 3129 3130 { 3131 // We want to temporarily turn off discovery by the 3132 // CM ref processor, if necessary, and turn it back on 3133 // on again later if we do. Using a scoped 3134 // NoRefDiscovery object will do this. 3135 NoRefDiscovery no_cm_discovery(ref_processor_cm()); 3136 3137 // Forget the current alloc region (we might even choose it to be part 3138 // of the collection set!). 3139 _allocator->release_mutator_alloc_region(); 3140 3141 // This timing is only used by the ergonomics to handle our pause target. 3142 // It is unclear why this should not include the full pause. We will 3143 // investigate this in CR 7178365. 3144 // 3145 // Preserving the old comment here if that helps the investigation: 3146 // 3147 // The elapsed time induced by the start time below deliberately elides 3148 // the possible verification above. 3149 double sample_start_time_sec = os::elapsedTime(); 3150 3151 g1_policy()->record_collection_pause_start(sample_start_time_sec); 3152 3153 if (collector_state()->during_initial_mark_pause()) { 3154 concurrent_mark()->checkpointRootsInitialPre(); 3155 } 3156 3157 g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor); 3158 3159 evacuation_info.set_collectionset_regions(collection_set()->region_length()); 3160 3161 // Make sure the remembered sets are up to date. This needs to be 3162 // done before register_humongous_regions_with_cset(), because the 3163 // remembered sets are used there to choose eager reclaim candidates. 3164 // If the remembered sets are not up to date we might miss some 3165 // entries that need to be handled. 3166 g1_rem_set()->cleanupHRRS(); 3167 3168 register_humongous_regions_with_cset(); 3169 3170 assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table."); 3171 3172 // We call this after finalize_cset() to 3173 // ensure that the CSet has been finalized. 3174 _cm->verify_no_cset_oops(); 3175 3176 if (_hr_printer.is_active()) { 3177 G1PrintCollectionSetClosure cl(&_hr_printer); 3178 _collection_set.iterate(&cl); 3179 } 3180 3181 // Initialize the GC alloc regions. 3182 _allocator->init_gc_alloc_regions(evacuation_info); 3183 3184 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length()); 3185 pre_evacuate_collection_set(); 3186 3187 // Actually do the work... 3188 evacuate_collection_set(evacuation_info, &per_thread_states); 3189 3190 post_evacuate_collection_set(evacuation_info, &per_thread_states); 3191 3192 const size_t* surviving_young_words = per_thread_states.surviving_young_words(); 3193 free_collection_set(&_collection_set, evacuation_info, surviving_young_words); 3194 3195 eagerly_reclaim_humongous_regions(); 3196 3197 record_obj_copy_mem_stats(); 3198 _survivor_evac_stats.adjust_desired_plab_sz(); 3199 _old_evac_stats.adjust_desired_plab_sz(); 3200 3201 // Start a new incremental collection set for the next pause. 3202 collection_set()->start_incremental_building(); 3203 3204 clear_cset_fast_test(); 3205 3206 guarantee(_eden.length() == 0, "eden should have been cleared"); 3207 g1_policy()->transfer_survivors_to_cset(survivor()); 3208 3209 if (evacuation_failed()) { 3210 set_used(recalculate_used()); 3211 if (_archive_allocator != NULL) { 3212 _archive_allocator->clear_used(); 3213 } 3214 for (uint i = 0; i < ParallelGCThreads; i++) { 3215 if (_evacuation_failed_info_array[i].has_failed()) { 3216 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]); 3217 } 3218 } 3219 } else { 3220 // The "used" of the the collection set have already been subtracted 3221 // when they were freed. Add in the bytes evacuated. 3222 increase_used(g1_policy()->bytes_copied_during_gc()); 3223 } 3224 3225 if (collector_state()->during_initial_mark_pause()) { 3226 // We have to do this before we notify the CM threads that 3227 // they can start working to make sure that all the 3228 // appropriate initialization is done on the CM object. 3229 concurrent_mark()->checkpointRootsInitialPost(); 3230 collector_state()->set_mark_in_progress(true); 3231 // Note that we don't actually trigger the CM thread at 3232 // this point. We do that later when we're sure that 3233 // the current thread has completed its logging output. 3234 } 3235 3236 allocate_dummy_regions(); 3237 3238 _allocator->init_mutator_alloc_region(); 3239 3240 { 3241 size_t expand_bytes = _heap_sizing_policy->expansion_amount(); 3242 if (expand_bytes > 0) { 3243 size_t bytes_before = capacity(); 3244 // No need for an ergo logging here, 3245 // expansion_amount() does this when it returns a value > 0. 3246 double expand_ms; 3247 if (!expand(expand_bytes, _workers, &expand_ms)) { 3248 // We failed to expand the heap. Cannot do anything about it. 3249 } 3250 g1_policy()->phase_times()->record_expand_heap_time(expand_ms); 3251 } 3252 } 3253 3254 // We redo the verification but now wrt to the new CSet which 3255 // has just got initialized after the previous CSet was freed. 3256 _cm->verify_no_cset_oops(); 3257 3258 // This timing is only used by the ergonomics to handle our pause target. 3259 // It is unclear why this should not include the full pause. We will 3260 // investigate this in CR 7178365. 3261 double sample_end_time_sec = os::elapsedTime(); 3262 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; 3263 size_t total_cards_scanned = per_thread_states.total_cards_scanned(); 3264 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc); 3265 3266 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before()); 3267 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc()); 3268 3269 MemoryService::track_memory_usage(); 3270 3271 // In prepare_for_verify() below we'll need to scan the deferred 3272 // update buffers to bring the RSets up-to-date if 3273 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning 3274 // the update buffers we'll probably need to scan cards on the 3275 // regions we just allocated to (i.e., the GC alloc 3276 // regions). However, during the last GC we called 3277 // set_saved_mark() on all the GC alloc regions, so card 3278 // scanning might skip the [saved_mark_word()...top()] area of 3279 // those regions (i.e., the area we allocated objects into 3280 // during the last GC). But it shouldn't. Given that 3281 // saved_mark_word() is conditional on whether the GC time stamp 3282 // on the region is current or not, by incrementing the GC time 3283 // stamp here we invalidate all the GC time stamps on all the 3284 // regions and saved_mark_word() will simply return top() for 3285 // all the regions. This is a nicer way of ensuring this rather 3286 // than iterating over the regions and fixing them. In fact, the 3287 // GC time stamp increment here also ensures that 3288 // saved_mark_word() will return top() between pauses, i.e., 3289 // during concurrent refinement. So we don't need the 3290 // is_gc_active() check to decided which top to use when 3291 // scanning cards (see CR 7039627). 3292 increment_gc_time_stamp(); 3293 3294 if (VerifyRememberedSets) { 3295 log_info(gc, verify)("[Verifying RemSets after GC]"); 3296 VerifyRegionRemSetClosure v_cl; 3297 heap_region_iterate(&v_cl); 3298 } 3299 3300 _verifier->verify_after_gc(); 3301 _verifier->check_bitmaps("GC End"); 3302 3303 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 3304 ref_processor_stw()->verify_no_references_recorded(); 3305 3306 // CM reference discovery will be re-enabled if necessary. 3307 } 3308 3309 #ifdef TRACESPINNING 3310 ParallelTaskTerminator::print_termination_counts(); 3311 #endif 3312 3313 gc_epilogue(false); 3314 } 3315 3316 // Print the remainder of the GC log output. 3317 if (evacuation_failed()) { 3318 log_info(gc)("To-space exhausted"); 3319 } 3320 3321 g1_policy()->print_phases(); 3322 heap_transition.print(); 3323 3324 // It is not yet to safe to tell the concurrent mark to 3325 // start as we have some optional output below. We don't want the 3326 // output from the concurrent mark thread interfering with this 3327 // logging output either. 3328 3329 _hrm.verify_optional(); 3330 _verifier->verify_region_sets_optional(); 3331 3332 TASKQUEUE_STATS_ONLY(print_taskqueue_stats()); 3333 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); 3334 3335 print_heap_after_gc(); 3336 print_heap_regions(); 3337 trace_heap_after_gc(_gc_tracer_stw); 3338 3339 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 3340 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 3341 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 3342 // before any GC notifications are raised. 3343 g1mm()->update_sizes(); 3344 3345 _gc_tracer_stw->report_evacuation_info(&evacuation_info); 3346 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold()); 3347 _gc_timer_stw->register_gc_end(); 3348 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions()); 3349 } 3350 // It should now be safe to tell the concurrent mark thread to start 3351 // without its logging output interfering with the logging output 3352 // that came from the pause. 3353 3354 if (should_start_conc_mark) { 3355 // CAUTION: after the doConcurrentMark() call below, 3356 // the concurrent marking thread(s) could be running 3357 // concurrently with us. Make sure that anything after 3358 // this point does not assume that we are the only GC thread 3359 // running. Note: of course, the actual marking work will 3360 // not start until the safepoint itself is released in 3361 // SuspendibleThreadSet::desynchronize(). 3362 doConcurrentMark(); 3363 } 3364 3365 return true; 3366 } 3367 3368 void G1CollectedHeap::remove_self_forwarding_pointers() { 3369 G1ParRemoveSelfForwardPtrsTask rsfp_task; 3370 workers()->run_task(&rsfp_task); 3371 } 3372 3373 void G1CollectedHeap::restore_after_evac_failure() { 3374 double remove_self_forwards_start = os::elapsedTime(); 3375 3376 remove_self_forwarding_pointers(); 3377 SharedRestorePreservedMarksTaskExecutor task_executor(workers()); 3378 _preserved_marks_set.restore(&task_executor); 3379 3380 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0); 3381 } 3382 3383 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) { 3384 if (!_evacuation_failed) { 3385 _evacuation_failed = true; 3386 } 3387 3388 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size()); 3389 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m); 3390 } 3391 3392 bool G1ParEvacuateFollowersClosure::offer_termination() { 3393 G1ParScanThreadState* const pss = par_scan_state(); 3394 start_term_time(); 3395 const bool res = terminator()->offer_termination(); 3396 end_term_time(); 3397 return res; 3398 } 3399 3400 void G1ParEvacuateFollowersClosure::do_void() { 3401 G1ParScanThreadState* const pss = par_scan_state(); 3402 pss->trim_queue(); 3403 do { 3404 pss->steal_and_trim_queue(queues()); 3405 } while (!offer_termination()); 3406 } 3407 3408 class G1ParTask : public AbstractGangTask { 3409 protected: 3410 G1CollectedHeap* _g1h; 3411 G1ParScanThreadStateSet* _pss; 3412 RefToScanQueueSet* _queues; 3413 G1RootProcessor* _root_processor; 3414 ParallelTaskTerminator _terminator; 3415 uint _n_workers; 3416 3417 public: 3418 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers) 3419 : AbstractGangTask("G1 collection"), 3420 _g1h(g1h), 3421 _pss(per_thread_states), 3422 _queues(task_queues), 3423 _root_processor(root_processor), 3424 _terminator(n_workers, _queues), 3425 _n_workers(n_workers) 3426 {} 3427 3428 void work(uint worker_id) { 3429 if (worker_id >= _n_workers) return; // no work needed this round 3430 3431 double start_sec = os::elapsedTime(); 3432 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec); 3433 3434 { 3435 ResourceMark rm; 3436 HandleMark hm; 3437 3438 ReferenceProcessor* rp = _g1h->ref_processor_stw(); 3439 3440 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 3441 pss->set_ref_processor(rp); 3442 3443 double start_strong_roots_sec = os::elapsedTime(); 3444 3445 _root_processor->evacuate_roots(pss->closures(), worker_id); 3446 3447 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, pss); 3448 3449 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid 3450 // treating the nmethods visited to act as roots for concurrent marking. 3451 // We only want to make sure that the oops in the nmethods are adjusted with regard to the 3452 // objects copied by the current evacuation. 3453 size_t cards_scanned = _g1h->g1_rem_set()->oops_into_collection_set_do(&push_heap_rs_cl, 3454 pss->closures()->weak_codeblobs(), 3455 worker_id); 3456 3457 _pss->add_cards_scanned(worker_id, cards_scanned); 3458 3459 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec; 3460 3461 double term_sec = 0.0; 3462 size_t evac_term_attempts = 0; 3463 { 3464 double start = os::elapsedTime(); 3465 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator); 3466 evac.do_void(); 3467 3468 evac_term_attempts = evac.term_attempts(); 3469 term_sec = evac.term_time(); 3470 double elapsed_sec = os::elapsedTime() - start; 3471 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec); 3472 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec); 3473 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts); 3474 } 3475 3476 assert(pss->queue_is_empty(), "should be empty"); 3477 3478 if (log_is_enabled(Debug, gc, task, stats)) { 3479 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); 3480 size_t lab_waste; 3481 size_t lab_undo_waste; 3482 pss->waste(lab_waste, lab_undo_waste); 3483 _g1h->print_termination_stats(worker_id, 3484 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */ 3485 strong_roots_sec * 1000.0, /* strong roots time */ 3486 term_sec * 1000.0, /* evac term time */ 3487 evac_term_attempts, /* evac term attempts */ 3488 lab_waste, /* alloc buffer waste */ 3489 lab_undo_waste /* undo waste */ 3490 ); 3491 } 3492 3493 // Close the inner scope so that the ResourceMark and HandleMark 3494 // destructors are executed here and are included as part of the 3495 // "GC Worker Time". 3496 } 3497 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime()); 3498 } 3499 }; 3500 3501 void G1CollectedHeap::print_termination_stats_hdr() { 3502 log_debug(gc, task, stats)("GC Termination Stats"); 3503 log_debug(gc, task, stats)(" elapsed --strong roots-- -------termination------- ------waste (KiB)------"); 3504 log_debug(gc, task, stats)("thr ms ms %% ms %% attempts total alloc undo"); 3505 log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------"); 3506 } 3507 3508 void G1CollectedHeap::print_termination_stats(uint worker_id, 3509 double elapsed_ms, 3510 double strong_roots_ms, 3511 double term_ms, 3512 size_t term_attempts, 3513 size_t alloc_buffer_waste, 3514 size_t undo_waste) const { 3515 log_debug(gc, task, stats) 3516 ("%3d %9.2f %9.2f %6.2f " 3517 "%9.2f %6.2f " SIZE_FORMAT_W(8) " " 3518 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7), 3519 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms, 3520 term_ms, term_ms * 100 / elapsed_ms, term_attempts, 3521 (alloc_buffer_waste + undo_waste) * HeapWordSize / K, 3522 alloc_buffer_waste * HeapWordSize / K, 3523 undo_waste * HeapWordSize / K); 3524 } 3525 3526 class G1StringSymbolTableUnlinkTask : public AbstractGangTask { 3527 private: 3528 BoolObjectClosure* _is_alive; 3529 int _initial_string_table_size; 3530 int _initial_symbol_table_size; 3531 3532 bool _process_strings; 3533 int _strings_processed; 3534 int _strings_removed; 3535 3536 bool _process_symbols; 3537 int _symbols_processed; 3538 int _symbols_removed; 3539 3540 public: 3541 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) : 3542 AbstractGangTask("String/Symbol Unlinking"), 3543 _is_alive(is_alive), 3544 _process_strings(process_strings), _strings_processed(0), _strings_removed(0), 3545 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) { 3546 3547 _initial_string_table_size = StringTable::the_table()->table_size(); 3548 _initial_symbol_table_size = SymbolTable::the_table()->table_size(); 3549 if (process_strings) { 3550 StringTable::clear_parallel_claimed_index(); 3551 } 3552 if (process_symbols) { 3553 SymbolTable::clear_parallel_claimed_index(); 3554 } 3555 } 3556 3557 ~G1StringSymbolTableUnlinkTask() { 3558 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size, 3559 "claim value %d after unlink less than initial string table size %d", 3560 StringTable::parallel_claimed_index(), _initial_string_table_size); 3561 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size, 3562 "claim value %d after unlink less than initial symbol table size %d", 3563 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size); 3564 3565 log_info(gc, stringtable)( 3566 "Cleaned string and symbol table, " 3567 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, " 3568 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed", 3569 strings_processed(), strings_removed(), 3570 symbols_processed(), symbols_removed()); 3571 } 3572 3573 void work(uint worker_id) { 3574 int strings_processed = 0; 3575 int strings_removed = 0; 3576 int symbols_processed = 0; 3577 int symbols_removed = 0; 3578 if (_process_strings) { 3579 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed); 3580 Atomic::add(strings_processed, &_strings_processed); 3581 Atomic::add(strings_removed, &_strings_removed); 3582 } 3583 if (_process_symbols) { 3584 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed); 3585 Atomic::add(symbols_processed, &_symbols_processed); 3586 Atomic::add(symbols_removed, &_symbols_removed); 3587 } 3588 } 3589 3590 size_t strings_processed() const { return (size_t)_strings_processed; } 3591 size_t strings_removed() const { return (size_t)_strings_removed; } 3592 3593 size_t symbols_processed() const { return (size_t)_symbols_processed; } 3594 size_t symbols_removed() const { return (size_t)_symbols_removed; } 3595 }; 3596 3597 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC { 3598 private: 3599 static Monitor* _lock; 3600 3601 BoolObjectClosure* const _is_alive; 3602 const bool _unloading_occurred; 3603 const uint _num_workers; 3604 3605 // Variables used to claim nmethods. 3606 CompiledMethod* _first_nmethod; 3607 volatile CompiledMethod* _claimed_nmethod; 3608 3609 // The list of nmethods that need to be processed by the second pass. 3610 volatile CompiledMethod* _postponed_list; 3611 volatile uint _num_entered_barrier; 3612 3613 public: 3614 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) : 3615 _is_alive(is_alive), 3616 _unloading_occurred(unloading_occurred), 3617 _num_workers(num_workers), 3618 _first_nmethod(NULL), 3619 _claimed_nmethod(NULL), 3620 _postponed_list(NULL), 3621 _num_entered_barrier(0) 3622 { 3623 CompiledMethod::increase_unloading_clock(); 3624 // Get first alive nmethod 3625 CompiledMethodIterator iter = CompiledMethodIterator(); 3626 if(iter.next_alive()) { 3627 _first_nmethod = iter.method(); 3628 } 3629 _claimed_nmethod = (volatile CompiledMethod*)_first_nmethod; 3630 } 3631 3632 ~G1CodeCacheUnloadingTask() { 3633 CodeCache::verify_clean_inline_caches(); 3634 3635 CodeCache::set_needs_cache_clean(false); 3636 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be"); 3637 3638 CodeCache::verify_icholder_relocations(); 3639 } 3640 3641 private: 3642 void add_to_postponed_list(CompiledMethod* nm) { 3643 CompiledMethod* old; 3644 do { 3645 old = (CompiledMethod*)_postponed_list; 3646 nm->set_unloading_next(old); 3647 } while ((CompiledMethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old); 3648 } 3649 3650 void clean_nmethod(CompiledMethod* nm) { 3651 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred); 3652 3653 if (postponed) { 3654 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet. 3655 add_to_postponed_list(nm); 3656 } 3657 3658 // Mark that this thread has been cleaned/unloaded. 3659 // After this call, it will be safe to ask if this nmethod was unloaded or not. 3660 nm->set_unloading_clock(CompiledMethod::global_unloading_clock()); 3661 } 3662 3663 void clean_nmethod_postponed(CompiledMethod* nm) { 3664 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred); 3665 } 3666 3667 static const int MaxClaimNmethods = 16; 3668 3669 void claim_nmethods(CompiledMethod** claimed_nmethods, int *num_claimed_nmethods) { 3670 CompiledMethod* first; 3671 CompiledMethodIterator last; 3672 3673 do { 3674 *num_claimed_nmethods = 0; 3675 3676 first = (CompiledMethod*)_claimed_nmethod; 3677 last = CompiledMethodIterator(first); 3678 3679 if (first != NULL) { 3680 3681 for (int i = 0; i < MaxClaimNmethods; i++) { 3682 if (!last.next_alive()) { 3683 break; 3684 } 3685 claimed_nmethods[i] = last.method(); 3686 (*num_claimed_nmethods)++; 3687 } 3688 } 3689 3690 } while ((CompiledMethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first); 3691 } 3692 3693 CompiledMethod* claim_postponed_nmethod() { 3694 CompiledMethod* claim; 3695 CompiledMethod* next; 3696 3697 do { 3698 claim = (CompiledMethod*)_postponed_list; 3699 if (claim == NULL) { 3700 return NULL; 3701 } 3702 3703 next = claim->unloading_next(); 3704 3705 } while ((CompiledMethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim); 3706 3707 return claim; 3708 } 3709 3710 public: 3711 // Mark that we're done with the first pass of nmethod cleaning. 3712 void barrier_mark(uint worker_id) { 3713 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 3714 _num_entered_barrier++; 3715 if (_num_entered_barrier == _num_workers) { 3716 ml.notify_all(); 3717 } 3718 } 3719 3720 // See if we have to wait for the other workers to 3721 // finish their first-pass nmethod cleaning work. 3722 void barrier_wait(uint worker_id) { 3723 if (_num_entered_barrier < _num_workers) { 3724 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 3725 while (_num_entered_barrier < _num_workers) { 3726 ml.wait(Mutex::_no_safepoint_check_flag, 0, false); 3727 } 3728 } 3729 } 3730 3731 // Cleaning and unloading of nmethods. Some work has to be postponed 3732 // to the second pass, when we know which nmethods survive. 3733 void work_first_pass(uint worker_id) { 3734 // The first nmethods is claimed by the first worker. 3735 if (worker_id == 0 && _first_nmethod != NULL) { 3736 clean_nmethod(_first_nmethod); 3737 _first_nmethod = NULL; 3738 } 3739 3740 int num_claimed_nmethods; 3741 CompiledMethod* claimed_nmethods[MaxClaimNmethods]; 3742 3743 while (true) { 3744 claim_nmethods(claimed_nmethods, &num_claimed_nmethods); 3745 3746 if (num_claimed_nmethods == 0) { 3747 break; 3748 } 3749 3750 for (int i = 0; i < num_claimed_nmethods; i++) { 3751 clean_nmethod(claimed_nmethods[i]); 3752 } 3753 } 3754 } 3755 3756 void work_second_pass(uint worker_id) { 3757 CompiledMethod* nm; 3758 // Take care of postponed nmethods. 3759 while ((nm = claim_postponed_nmethod()) != NULL) { 3760 clean_nmethod_postponed(nm); 3761 } 3762 } 3763 }; 3764 3765 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never); 3766 3767 class G1KlassCleaningTask : public StackObj { 3768 BoolObjectClosure* _is_alive; 3769 volatile jint _clean_klass_tree_claimed; 3770 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator; 3771 3772 public: 3773 G1KlassCleaningTask(BoolObjectClosure* is_alive) : 3774 _is_alive(is_alive), 3775 _clean_klass_tree_claimed(0), 3776 _klass_iterator() { 3777 } 3778 3779 private: 3780 bool claim_clean_klass_tree_task() { 3781 if (_clean_klass_tree_claimed) { 3782 return false; 3783 } 3784 3785 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0; 3786 } 3787 3788 InstanceKlass* claim_next_klass() { 3789 Klass* klass; 3790 do { 3791 klass =_klass_iterator.next_klass(); 3792 } while (klass != NULL && !klass->is_instance_klass()); 3793 3794 // this can be null so don't call InstanceKlass::cast 3795 return static_cast<InstanceKlass*>(klass); 3796 } 3797 3798 public: 3799 3800 void clean_klass(InstanceKlass* ik) { 3801 ik->clean_weak_instanceklass_links(_is_alive); 3802 } 3803 3804 void work() { 3805 ResourceMark rm; 3806 3807 // One worker will clean the subklass/sibling klass tree. 3808 if (claim_clean_klass_tree_task()) { 3809 Klass::clean_subklass_tree(_is_alive); 3810 } 3811 3812 // All workers will help cleaning the classes, 3813 InstanceKlass* klass; 3814 while ((klass = claim_next_klass()) != NULL) { 3815 clean_klass(klass); 3816 } 3817 } 3818 }; 3819 3820 // To minimize the remark pause times, the tasks below are done in parallel. 3821 class G1ParallelCleaningTask : public AbstractGangTask { 3822 private: 3823 G1StringSymbolTableUnlinkTask _string_symbol_task; 3824 G1CodeCacheUnloadingTask _code_cache_task; 3825 G1KlassCleaningTask _klass_cleaning_task; 3826 3827 public: 3828 // The constructor is run in the VMThread. 3829 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) : 3830 AbstractGangTask("Parallel Cleaning"), 3831 _string_symbol_task(is_alive, process_strings, process_symbols), 3832 _code_cache_task(num_workers, is_alive, unloading_occurred), 3833 _klass_cleaning_task(is_alive) { 3834 } 3835 3836 // The parallel work done by all worker threads. 3837 void work(uint worker_id) { 3838 // Do first pass of code cache cleaning. 3839 _code_cache_task.work_first_pass(worker_id); 3840 3841 // Let the threads mark that the first pass is done. 3842 _code_cache_task.barrier_mark(worker_id); 3843 3844 // Clean the Strings and Symbols. 3845 _string_symbol_task.work(worker_id); 3846 3847 // Wait for all workers to finish the first code cache cleaning pass. 3848 _code_cache_task.barrier_wait(worker_id); 3849 3850 // Do the second code cache cleaning work, which realize on 3851 // the liveness information gathered during the first pass. 3852 _code_cache_task.work_second_pass(worker_id); 3853 3854 // Clean all klasses that were not unloaded. 3855 _klass_cleaning_task.work(); 3856 } 3857 }; 3858 3859 3860 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive, 3861 bool process_strings, 3862 bool process_symbols, 3863 bool class_unloading_occurred) { 3864 uint n_workers = workers()->active_workers(); 3865 3866 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, 3867 n_workers, class_unloading_occurred); 3868 workers()->run_task(&g1_unlink_task); 3869 } 3870 3871 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive, 3872 bool process_strings, bool process_symbols) { 3873 { // Timing scope 3874 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols); 3875 workers()->run_task(&g1_unlink_task); 3876 } 3877 } 3878 3879 class G1RedirtyLoggedCardsTask : public AbstractGangTask { 3880 private: 3881 DirtyCardQueueSet* _queue; 3882 G1CollectedHeap* _g1h; 3883 public: 3884 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"), 3885 _queue(queue), _g1h(g1h) { } 3886 3887 virtual void work(uint worker_id) { 3888 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times(); 3889 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id); 3890 3891 RedirtyLoggedCardTableEntryClosure cl(_g1h); 3892 _queue->par_apply_closure_to_all_completed_buffers(&cl); 3893 3894 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied()); 3895 } 3896 }; 3897 3898 void G1CollectedHeap::redirty_logged_cards() { 3899 double redirty_logged_cards_start = os::elapsedTime(); 3900 3901 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this); 3902 dirty_card_queue_set().reset_for_par_iteration(); 3903 workers()->run_task(&redirty_task); 3904 3905 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set(); 3906 dcq.merge_bufferlists(&dirty_card_queue_set()); 3907 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed"); 3908 3909 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0); 3910 } 3911 3912 // Weak Reference Processing support 3913 3914 // An always "is_alive" closure that is used to preserve referents. 3915 // If the object is non-null then it's alive. Used in the preservation 3916 // of referent objects that are pointed to by reference objects 3917 // discovered by the CM ref processor. 3918 class G1AlwaysAliveClosure: public BoolObjectClosure { 3919 G1CollectedHeap* _g1; 3920 public: 3921 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 3922 bool do_object_b(oop p) { 3923 if (p != NULL) { 3924 return true; 3925 } 3926 return false; 3927 } 3928 }; 3929 3930 bool G1STWIsAliveClosure::do_object_b(oop p) { 3931 // An object is reachable if it is outside the collection set, 3932 // or is inside and copied. 3933 return !_g1->is_in_cset(p) || p->is_forwarded(); 3934 } 3935 3936 // Non Copying Keep Alive closure 3937 class G1KeepAliveClosure: public OopClosure { 3938 G1CollectedHeap* _g1; 3939 public: 3940 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 3941 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } 3942 void do_oop(oop* p) { 3943 oop obj = *p; 3944 assert(obj != NULL, "the caller should have filtered out NULL values"); 3945 3946 const InCSetState cset_state = _g1->in_cset_state(obj); 3947 if (!cset_state.is_in_cset_or_humongous()) { 3948 return; 3949 } 3950 if (cset_state.is_in_cset()) { 3951 assert( obj->is_forwarded(), "invariant" ); 3952 *p = obj->forwardee(); 3953 } else { 3954 assert(!obj->is_forwarded(), "invariant" ); 3955 assert(cset_state.is_humongous(), 3956 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value()); 3957 _g1->set_humongous_is_live(obj); 3958 } 3959 } 3960 }; 3961 3962 // Copying Keep Alive closure - can be called from both 3963 // serial and parallel code as long as different worker 3964 // threads utilize different G1ParScanThreadState instances 3965 // and different queues. 3966 3967 class G1CopyingKeepAliveClosure: public OopClosure { 3968 G1CollectedHeap* _g1h; 3969 OopClosure* _copy_non_heap_obj_cl; 3970 G1ParScanThreadState* _par_scan_state; 3971 3972 public: 3973 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, 3974 OopClosure* non_heap_obj_cl, 3975 G1ParScanThreadState* pss): 3976 _g1h(g1h), 3977 _copy_non_heap_obj_cl(non_heap_obj_cl), 3978 _par_scan_state(pss) 3979 {} 3980 3981 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 3982 virtual void do_oop( oop* p) { do_oop_work(p); } 3983 3984 template <class T> void do_oop_work(T* p) { 3985 oop obj = oopDesc::load_decode_heap_oop(p); 3986 3987 if (_g1h->is_in_cset_or_humongous(obj)) { 3988 // If the referent object has been forwarded (either copied 3989 // to a new location or to itself in the event of an 3990 // evacuation failure) then we need to update the reference 3991 // field and, if both reference and referent are in the G1 3992 // heap, update the RSet for the referent. 3993 // 3994 // If the referent has not been forwarded then we have to keep 3995 // it alive by policy. Therefore we have copy the referent. 3996 // 3997 // If the reference field is in the G1 heap then we can push 3998 // on the PSS queue. When the queue is drained (after each 3999 // phase of reference processing) the object and it's followers 4000 // will be copied, the reference field set to point to the 4001 // new location, and the RSet updated. Otherwise we need to 4002 // use the the non-heap or metadata closures directly to copy 4003 // the referent object and update the pointer, while avoiding 4004 // updating the RSet. 4005 4006 if (_g1h->is_in_g1_reserved(p)) { 4007 _par_scan_state->push_on_queue(p); 4008 } else { 4009 assert(!Metaspace::contains((const void*)p), 4010 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p)); 4011 _copy_non_heap_obj_cl->do_oop(p); 4012 } 4013 } 4014 } 4015 }; 4016 4017 // Serial drain queue closure. Called as the 'complete_gc' 4018 // closure for each discovered list in some of the 4019 // reference processing phases. 4020 4021 class G1STWDrainQueueClosure: public VoidClosure { 4022 protected: 4023 G1CollectedHeap* _g1h; 4024 G1ParScanThreadState* _par_scan_state; 4025 4026 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 4027 4028 public: 4029 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : 4030 _g1h(g1h), 4031 _par_scan_state(pss) 4032 { } 4033 4034 void do_void() { 4035 G1ParScanThreadState* const pss = par_scan_state(); 4036 pss->trim_queue(); 4037 } 4038 }; 4039 4040 // Parallel Reference Processing closures 4041 4042 // Implementation of AbstractRefProcTaskExecutor for parallel reference 4043 // processing during G1 evacuation pauses. 4044 4045 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 4046 private: 4047 G1CollectedHeap* _g1h; 4048 G1ParScanThreadStateSet* _pss; 4049 RefToScanQueueSet* _queues; 4050 WorkGang* _workers; 4051 uint _active_workers; 4052 4053 public: 4054 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, 4055 G1ParScanThreadStateSet* per_thread_states, 4056 WorkGang* workers, 4057 RefToScanQueueSet *task_queues, 4058 uint n_workers) : 4059 _g1h(g1h), 4060 _pss(per_thread_states), 4061 _queues(task_queues), 4062 _workers(workers), 4063 _active_workers(n_workers) 4064 { 4065 g1h->ref_processor_stw()->set_active_mt_degree(n_workers); 4066 } 4067 4068 // Executes the given task using concurrent marking worker threads. 4069 virtual void execute(ProcessTask& task); 4070 virtual void execute(EnqueueTask& task); 4071 }; 4072 4073 // Gang task for possibly parallel reference processing 4074 4075 class G1STWRefProcTaskProxy: public AbstractGangTask { 4076 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 4077 ProcessTask& _proc_task; 4078 G1CollectedHeap* _g1h; 4079 G1ParScanThreadStateSet* _pss; 4080 RefToScanQueueSet* _task_queues; 4081 ParallelTaskTerminator* _terminator; 4082 4083 public: 4084 G1STWRefProcTaskProxy(ProcessTask& proc_task, 4085 G1CollectedHeap* g1h, 4086 G1ParScanThreadStateSet* per_thread_states, 4087 RefToScanQueueSet *task_queues, 4088 ParallelTaskTerminator* terminator) : 4089 AbstractGangTask("Process reference objects in parallel"), 4090 _proc_task(proc_task), 4091 _g1h(g1h), 4092 _pss(per_thread_states), 4093 _task_queues(task_queues), 4094 _terminator(terminator) 4095 {} 4096 4097 virtual void work(uint worker_id) { 4098 // The reference processing task executed by a single worker. 4099 ResourceMark rm; 4100 HandleMark hm; 4101 4102 G1STWIsAliveClosure is_alive(_g1h); 4103 4104 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 4105 pss->set_ref_processor(NULL); 4106 4107 // Keep alive closure. 4108 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss); 4109 4110 // Complete GC closure 4111 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator); 4112 4113 // Call the reference processing task's work routine. 4114 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); 4115 4116 // Note we cannot assert that the refs array is empty here as not all 4117 // of the processing tasks (specifically phase2 - pp2_work) execute 4118 // the complete_gc closure (which ordinarily would drain the queue) so 4119 // the queue may not be empty. 4120 } 4121 }; 4122 4123 // Driver routine for parallel reference processing. 4124 // Creates an instance of the ref processing gang 4125 // task and has the worker threads execute it. 4126 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) { 4127 assert(_workers != NULL, "Need parallel worker threads."); 4128 4129 ParallelTaskTerminator terminator(_active_workers, _queues); 4130 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator); 4131 4132 _workers->run_task(&proc_task_proxy); 4133 } 4134 4135 // Gang task for parallel reference enqueueing. 4136 4137 class G1STWRefEnqueueTaskProxy: public AbstractGangTask { 4138 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; 4139 EnqueueTask& _enq_task; 4140 4141 public: 4142 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) : 4143 AbstractGangTask("Enqueue reference objects in parallel"), 4144 _enq_task(enq_task) 4145 { } 4146 4147 virtual void work(uint worker_id) { 4148 _enq_task.work(worker_id); 4149 } 4150 }; 4151 4152 // Driver routine for parallel reference enqueueing. 4153 // Creates an instance of the ref enqueueing gang 4154 // task and has the worker threads execute it. 4155 4156 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) { 4157 assert(_workers != NULL, "Need parallel worker threads."); 4158 4159 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task); 4160 4161 _workers->run_task(&enq_task_proxy); 4162 } 4163 4164 // End of weak reference support closures 4165 4166 // Abstract task used to preserve (i.e. copy) any referent objects 4167 // that are in the collection set and are pointed to by reference 4168 // objects discovered by the CM ref processor. 4169 4170 class G1ParPreserveCMReferentsTask: public AbstractGangTask { 4171 protected: 4172 G1CollectedHeap* _g1h; 4173 G1ParScanThreadStateSet* _pss; 4174 RefToScanQueueSet* _queues; 4175 ParallelTaskTerminator _terminator; 4176 uint _n_workers; 4177 4178 public: 4179 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) : 4180 AbstractGangTask("ParPreserveCMReferents"), 4181 _g1h(g1h), 4182 _pss(per_thread_states), 4183 _queues(task_queues), 4184 _terminator(workers, _queues), 4185 _n_workers(workers) 4186 { 4187 g1h->ref_processor_cm()->set_active_mt_degree(workers); 4188 } 4189 4190 void work(uint worker_id) { 4191 G1GCParPhaseTimesTracker x(_g1h->g1_policy()->phase_times(), G1GCPhaseTimes::PreserveCMReferents, worker_id); 4192 4193 ResourceMark rm; 4194 HandleMark hm; 4195 4196 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 4197 pss->set_ref_processor(NULL); 4198 assert(pss->queue_is_empty(), "both queue and overflow should be empty"); 4199 4200 // Is alive closure 4201 G1AlwaysAliveClosure always_alive(_g1h); 4202 4203 // Copying keep alive closure. Applied to referent objects that need 4204 // to be copied. 4205 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss); 4206 4207 ReferenceProcessor* rp = _g1h->ref_processor_cm(); 4208 4209 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q(); 4210 uint stride = MIN2(MAX2(_n_workers, 1U), limit); 4211 4212 // limit is set using max_num_q() - which was set using ParallelGCThreads. 4213 // So this must be true - but assert just in case someone decides to 4214 // change the worker ids. 4215 assert(worker_id < limit, "sanity"); 4216 assert(!rp->discovery_is_atomic(), "check this code"); 4217 4218 // Select discovered lists [i, i+stride, i+2*stride,...,limit) 4219 for (uint idx = worker_id; idx < limit; idx += stride) { 4220 DiscoveredList& ref_list = rp->discovered_refs()[idx]; 4221 4222 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive); 4223 while (iter.has_next()) { 4224 // Since discovery is not atomic for the CM ref processor, we 4225 // can see some null referent objects. 4226 iter.load_ptrs(DEBUG_ONLY(true)); 4227 oop ref = iter.obj(); 4228 4229 // This will filter nulls. 4230 if (iter.is_referent_alive()) { 4231 iter.make_referent_alive(); 4232 } 4233 iter.move_to_next(); 4234 } 4235 } 4236 4237 // Drain the queue - which may cause stealing 4238 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator); 4239 drain_queue.do_void(); 4240 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure 4241 assert(pss->queue_is_empty(), "should be"); 4242 } 4243 }; 4244 4245 void G1CollectedHeap::process_weak_jni_handles() { 4246 double ref_proc_start = os::elapsedTime(); 4247 4248 G1STWIsAliveClosure is_alive(this); 4249 G1KeepAliveClosure keep_alive(this); 4250 JNIHandles::weak_oops_do(&is_alive, &keep_alive); 4251 4252 double ref_proc_time = os::elapsedTime() - ref_proc_start; 4253 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 4254 } 4255 4256 void G1CollectedHeap::preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states) { 4257 // Any reference objects, in the collection set, that were 'discovered' 4258 // by the CM ref processor should have already been copied (either by 4259 // applying the external root copy closure to the discovered lists, or 4260 // by following an RSet entry). 4261 // 4262 // But some of the referents, that are in the collection set, that these 4263 // reference objects point to may not have been copied: the STW ref 4264 // processor would have seen that the reference object had already 4265 // been 'discovered' and would have skipped discovering the reference, 4266 // but would not have treated the reference object as a regular oop. 4267 // As a result the copy closure would not have been applied to the 4268 // referent object. 4269 // 4270 // We need to explicitly copy these referent objects - the references 4271 // will be processed at the end of remarking. 4272 // 4273 // We also need to do this copying before we process the reference 4274 // objects discovered by the STW ref processor in case one of these 4275 // referents points to another object which is also referenced by an 4276 // object discovered by the STW ref processor. 4277 double preserve_cm_referents_time = 0.0; 4278 4279 // To avoid spawning task when there is no work to do, check that 4280 // a concurrent cycle is active and that some references have been 4281 // discovered. 4282 if (concurrent_mark()->cmThread()->during_cycle() && 4283 ref_processor_cm()->has_discovered_references()) { 4284 double preserve_cm_referents_start = os::elapsedTime(); 4285 uint no_of_gc_workers = workers()->active_workers(); 4286 G1ParPreserveCMReferentsTask keep_cm_referents(this, 4287 per_thread_states, 4288 no_of_gc_workers, 4289 _task_queues); 4290 workers()->run_task(&keep_cm_referents); 4291 preserve_cm_referents_time = os::elapsedTime() - preserve_cm_referents_start; 4292 } 4293 4294 g1_policy()->phase_times()->record_preserve_cm_referents_time_ms(preserve_cm_referents_time * 1000.0); 4295 } 4296 4297 // Weak Reference processing during an evacuation pause (part 1). 4298 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) { 4299 double ref_proc_start = os::elapsedTime(); 4300 4301 ReferenceProcessor* rp = _ref_processor_stw; 4302 assert(rp->discovery_enabled(), "should have been enabled"); 4303 4304 // Closure to test whether a referent is alive. 4305 G1STWIsAliveClosure is_alive(this); 4306 4307 // Even when parallel reference processing is enabled, the processing 4308 // of JNI refs is serial and performed serially by the current thread 4309 // rather than by a worker. The following PSS will be used for processing 4310 // JNI refs. 4311 4312 // Use only a single queue for this PSS. 4313 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0); 4314 pss->set_ref_processor(NULL); 4315 assert(pss->queue_is_empty(), "pre-condition"); 4316 4317 // Keep alive closure. 4318 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss); 4319 4320 // Serial Complete GC closure 4321 G1STWDrainQueueClosure drain_queue(this, pss); 4322 4323 // Setup the soft refs policy... 4324 rp->setup_policy(false); 4325 4326 ReferenceProcessorStats stats; 4327 if (!rp->processing_is_mt()) { 4328 // Serial reference processing... 4329 stats = rp->process_discovered_references(&is_alive, 4330 &keep_alive, 4331 &drain_queue, 4332 NULL, 4333 _gc_timer_stw); 4334 } else { 4335 uint no_of_gc_workers = workers()->active_workers(); 4336 4337 // Parallel reference processing 4338 assert(no_of_gc_workers <= rp->max_num_q(), 4339 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u", 4340 no_of_gc_workers, rp->max_num_q()); 4341 4342 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers); 4343 stats = rp->process_discovered_references(&is_alive, 4344 &keep_alive, 4345 &drain_queue, 4346 &par_task_executor, 4347 _gc_timer_stw); 4348 } 4349 4350 _gc_tracer_stw->report_gc_reference_stats(stats); 4351 4352 // We have completed copying any necessary live referent objects. 4353 assert(pss->queue_is_empty(), "both queue and overflow should be empty"); 4354 4355 double ref_proc_time = os::elapsedTime() - ref_proc_start; 4356 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 4357 } 4358 4359 // Weak Reference processing during an evacuation pause (part 2). 4360 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) { 4361 double ref_enq_start = os::elapsedTime(); 4362 4363 ReferenceProcessor* rp = _ref_processor_stw; 4364 assert(!rp->discovery_enabled(), "should have been disabled as part of processing"); 4365 4366 // Now enqueue any remaining on the discovered lists on to 4367 // the pending list. 4368 if (!rp->processing_is_mt()) { 4369 // Serial reference processing... 4370 rp->enqueue_discovered_references(); 4371 } else { 4372 // Parallel reference enqueueing 4373 4374 uint n_workers = workers()->active_workers(); 4375 4376 assert(n_workers <= rp->max_num_q(), 4377 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u", 4378 n_workers, rp->max_num_q()); 4379 4380 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers); 4381 rp->enqueue_discovered_references(&par_task_executor); 4382 } 4383 4384 rp->verify_no_references_recorded(); 4385 assert(!rp->discovery_enabled(), "should have been disabled"); 4386 4387 // FIXME 4388 // CM's reference processing also cleans up the string and symbol tables. 4389 // Should we do that here also? We could, but it is a serial operation 4390 // and could significantly increase the pause time. 4391 4392 double ref_enq_time = os::elapsedTime() - ref_enq_start; 4393 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0); 4394 } 4395 4396 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) { 4397 double merge_pss_time_start = os::elapsedTime(); 4398 per_thread_states->flush(); 4399 g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0); 4400 } 4401 4402 void G1CollectedHeap::pre_evacuate_collection_set() { 4403 _expand_heap_after_alloc_failure = true; 4404 _evacuation_failed = false; 4405 4406 // Disable the hot card cache. 4407 _hot_card_cache->reset_hot_cache_claimed_index(); 4408 _hot_card_cache->set_use_cache(false); 4409 4410 g1_rem_set()->prepare_for_oops_into_collection_set_do(); 4411 _preserved_marks_set.assert_empty(); 4412 } 4413 4414 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) { 4415 // Should G1EvacuationFailureALot be in effect for this GC? 4416 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) 4417 4418 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty"); 4419 4420 G1GCPhaseTimes* phase_times = g1_policy()->phase_times(); 4421 4422 // InitialMark needs claim bits to keep track of the marked-through CLDs. 4423 if (collector_state()->during_initial_mark_pause()) { 4424 double start_clear_claimed_marks = os::elapsedTime(); 4425 4426 ClassLoaderDataGraph::clear_claimed_marks(); 4427 4428 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0; 4429 phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms); 4430 } 4431 4432 double start_par_time_sec = os::elapsedTime(); 4433 double end_par_time_sec; 4434 4435 { 4436 const uint n_workers = workers()->active_workers(); 4437 G1RootProcessor root_processor(this, n_workers); 4438 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers); 4439 4440 print_termination_stats_hdr(); 4441 4442 workers()->run_task(&g1_par_task); 4443 end_par_time_sec = os::elapsedTime(); 4444 4445 // Closing the inner scope will execute the destructor 4446 // for the G1RootProcessor object. We record the current 4447 // elapsed time before closing the scope so that time 4448 // taken for the destructor is NOT included in the 4449 // reported parallel time. 4450 } 4451 4452 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0; 4453 phase_times->record_par_time(par_time_ms); 4454 4455 double code_root_fixup_time_ms = 4456 (os::elapsedTime() - end_par_time_sec) * 1000.0; 4457 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms); 4458 } 4459 4460 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) { 4461 // Process any discovered reference objects - we have 4462 // to do this _before_ we retire the GC alloc regions 4463 // as we may have to copy some 'reachable' referent 4464 // objects (and their reachable sub-graphs) that were 4465 // not copied during the pause. 4466 if (g1_policy()->should_process_references()) { 4467 preserve_cm_referents(per_thread_states); 4468 process_discovered_references(per_thread_states); 4469 } else { 4470 ref_processor_stw()->verify_no_references_recorded(); 4471 process_weak_jni_handles(); 4472 } 4473 4474 if (G1StringDedup::is_enabled()) { 4475 double fixup_start = os::elapsedTime(); 4476 4477 G1STWIsAliveClosure is_alive(this); 4478 G1KeepAliveClosure keep_alive(this); 4479 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times()); 4480 4481 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0; 4482 g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms); 4483 } 4484 4485 g1_rem_set()->cleanup_after_oops_into_collection_set_do(); 4486 4487 if (evacuation_failed()) { 4488 restore_after_evac_failure(); 4489 4490 // Reset the G1EvacuationFailureALot counters and flags 4491 // Note: the values are reset only when an actual 4492 // evacuation failure occurs. 4493 NOT_PRODUCT(reset_evacuation_should_fail();) 4494 } 4495 4496 _preserved_marks_set.assert_empty(); 4497 4498 // Enqueue any remaining references remaining on the STW 4499 // reference processor's discovered lists. We need to do 4500 // this after the card table is cleaned (and verified) as 4501 // the act of enqueueing entries on to the pending list 4502 // will log these updates (and dirty their associated 4503 // cards). We need these updates logged to update any 4504 // RSets. 4505 if (g1_policy()->should_process_references()) { 4506 enqueue_discovered_references(per_thread_states); 4507 } else { 4508 g1_policy()->phase_times()->record_ref_enq_time(0); 4509 } 4510 4511 _allocator->release_gc_alloc_regions(evacuation_info); 4512 4513 merge_per_thread_state_info(per_thread_states); 4514 4515 // Reset and re-enable the hot card cache. 4516 // Note the counts for the cards in the regions in the 4517 // collection set are reset when the collection set is freed. 4518 _hot_card_cache->reset_hot_cache(); 4519 _hot_card_cache->set_use_cache(true); 4520 4521 purge_code_root_memory(); 4522 4523 redirty_logged_cards(); 4524 #if defined(COMPILER2) || INCLUDE_JVMCI 4525 DerivedPointerTable::update_pointers(); 4526 #endif 4527 g1_policy()->print_age_table(); 4528 } 4529 4530 void G1CollectedHeap::record_obj_copy_mem_stats() { 4531 g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize); 4532 4533 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats), 4534 create_g1_evac_summary(&_old_evac_stats)); 4535 } 4536 4537 void G1CollectedHeap::free_region(HeapRegion* hr, 4538 FreeRegionList* free_list, 4539 bool skip_remset, 4540 bool skip_hot_card_cache, 4541 bool locked) { 4542 assert(!hr->is_free(), "the region should not be free"); 4543 assert(!hr->is_empty(), "the region should not be empty"); 4544 assert(_hrm.is_available(hr->hrm_index()), "region should be committed"); 4545 assert(free_list != NULL, "pre-condition"); 4546 4547 if (G1VerifyBitmaps) { 4548 MemRegion mr(hr->bottom(), hr->end()); 4549 concurrent_mark()->clearRangePrevBitmap(mr); 4550 } 4551 4552 // Clear the card counts for this region. 4553 // Note: we only need to do this if the region is not young 4554 // (since we don't refine cards in young regions). 4555 if (!skip_hot_card_cache && !hr->is_young()) { 4556 _hot_card_cache->reset_card_counts(hr); 4557 } 4558 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */); 4559 free_list->add_ordered(hr); 4560 } 4561 4562 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 4563 FreeRegionList* free_list, 4564 bool skip_remset) { 4565 assert(hr->is_humongous(), "this is only for humongous regions"); 4566 assert(free_list != NULL, "pre-condition"); 4567 hr->clear_humongous(); 4568 free_region(hr, free_list, skip_remset); 4569 } 4570 4571 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed, 4572 const uint humongous_regions_removed) { 4573 if (old_regions_removed > 0 || humongous_regions_removed > 0) { 4574 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 4575 _old_set.bulk_remove(old_regions_removed); 4576 _humongous_set.bulk_remove(humongous_regions_removed); 4577 } 4578 4579 } 4580 4581 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) { 4582 assert(list != NULL, "list can't be null"); 4583 if (!list->is_empty()) { 4584 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag); 4585 _hrm.insert_list_into_free_list(list); 4586 } 4587 } 4588 4589 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) { 4590 decrease_used(bytes); 4591 } 4592 4593 class G1ParScrubRemSetTask: public AbstractGangTask { 4594 protected: 4595 G1RemSet* _g1rs; 4596 HeapRegionClaimer _hrclaimer; 4597 4598 public: 4599 G1ParScrubRemSetTask(G1RemSet* g1_rs, uint num_workers) : 4600 AbstractGangTask("G1 ScrubRS"), 4601 _g1rs(g1_rs), 4602 _hrclaimer(num_workers) { 4603 } 4604 4605 void work(uint worker_id) { 4606 _g1rs->scrub(worker_id, &_hrclaimer); 4607 } 4608 }; 4609 4610 void G1CollectedHeap::scrub_rem_set() { 4611 uint num_workers = workers()->active_workers(); 4612 G1ParScrubRemSetTask g1_par_scrub_rs_task(g1_rem_set(), num_workers); 4613 workers()->run_task(&g1_par_scrub_rs_task); 4614 } 4615 4616 class G1FreeCollectionSetTask : public AbstractGangTask { 4617 private: 4618 4619 // Closure applied to all regions in the collection set to do work that needs to 4620 // be done serially in a single thread. 4621 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure { 4622 private: 4623 EvacuationInfo* _evacuation_info; 4624 const size_t* _surviving_young_words; 4625 4626 // Bytes used in successfully evacuated regions before the evacuation. 4627 size_t _before_used_bytes; 4628 // Bytes used in unsucessfully evacuated regions before the evacuation 4629 size_t _after_used_bytes; 4630 4631 size_t _bytes_allocated_in_old_since_last_gc; 4632 4633 size_t _failure_used_words; 4634 size_t _failure_waste_words; 4635 4636 FreeRegionList _local_free_list; 4637 public: 4638 G1SerialFreeCollectionSetClosure(EvacuationInfo* evacuation_info, const size_t* surviving_young_words) : 4639 HeapRegionClosure(), 4640 _evacuation_info(evacuation_info), 4641 _surviving_young_words(surviving_young_words), 4642 _before_used_bytes(0), 4643 _after_used_bytes(0), 4644 _bytes_allocated_in_old_since_last_gc(0), 4645 _failure_used_words(0), 4646 _failure_waste_words(0), 4647 _local_free_list("Local Region List for CSet Freeing") { 4648 } 4649 4650 virtual bool doHeapRegion(HeapRegion* r) { 4651 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4652 4653 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index()); 4654 g1h->clear_in_cset(r); 4655 4656 if (r->is_young()) { 4657 assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(), 4658 "Young index %d is wrong for region %u of type %s with %u young regions", 4659 r->young_index_in_cset(), 4660 r->hrm_index(), 4661 r->get_type_str(), 4662 g1h->collection_set()->young_region_length()); 4663 size_t words_survived = _surviving_young_words[r->young_index_in_cset()]; 4664 r->record_surv_words_in_group(words_survived); 4665 } 4666 4667 if (!r->evacuation_failed()) { 4668 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index()); 4669 _before_used_bytes += r->used(); 4670 g1h->free_region(r, 4671 &_local_free_list, 4672 true, /* skip_remset */ 4673 true, /* skip_hot_card_cache */ 4674 true /* locked */); 4675 } else { 4676 r->uninstall_surv_rate_group(); 4677 r->set_young_index_in_cset(-1); 4678 r->set_evacuation_failed(false); 4679 // When moving a young gen region to old gen, we "allocate" that whole region 4680 // there. This is in addition to any already evacuated objects. Notify the 4681 // policy about that. 4682 // Old gen regions do not cause an additional allocation: both the objects 4683 // still in the region and the ones already moved are accounted for elsewhere. 4684 if (r->is_young()) { 4685 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes; 4686 } 4687 // The region is now considered to be old. 4688 r->set_old(); 4689 // Do some allocation statistics accounting. Regions that failed evacuation 4690 // are always made old, so there is no need to update anything in the young 4691 // gen statistics, but we need to update old gen statistics. 4692 size_t used_words = r->marked_bytes() / HeapWordSize; 4693 4694 _failure_used_words += used_words; 4695 _failure_waste_words += HeapRegion::GrainWords - used_words; 4696 4697 g1h->old_set_add(r); 4698 _after_used_bytes += r->used(); 4699 } 4700 return false; 4701 } 4702 4703 void complete_work() { 4704 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4705 4706 _evacuation_info->set_regions_freed(_local_free_list.length()); 4707 _evacuation_info->increment_collectionset_used_after(_after_used_bytes); 4708 4709 g1h->prepend_to_freelist(&_local_free_list); 4710 g1h->decrement_summary_bytes(_before_used_bytes); 4711 4712 G1Policy* policy = g1h->g1_policy(); 4713 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc); 4714 4715 g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words); 4716 } 4717 }; 4718 4719 G1CollectionSet* _collection_set; 4720 G1SerialFreeCollectionSetClosure _cl; 4721 const size_t* _surviving_young_words; 4722 4723 size_t _rs_lengths; 4724 4725 volatile jint _serial_work_claim; 4726 4727 struct WorkItem { 4728 uint region_idx; 4729 bool is_young; 4730 bool evacuation_failed; 4731 4732 WorkItem(HeapRegion* r) { 4733 region_idx = r->hrm_index(); 4734 is_young = r->is_young(); 4735 evacuation_failed = r->evacuation_failed(); 4736 } 4737 }; 4738 4739 volatile size_t _parallel_work_claim; 4740 size_t _num_work_items; 4741 WorkItem* _work_items; 4742 4743 void do_serial_work() { 4744 // Need to grab the lock to be allowed to modify the old region list. 4745 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 4746 _collection_set->iterate(&_cl); 4747 } 4748 4749 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) { 4750 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4751 4752 HeapRegion* r = g1h->region_at(region_idx); 4753 assert(!g1h->is_on_master_free_list(r), "sanity"); 4754 4755 Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths); 4756 4757 if (!is_young) { 4758 g1h->_hot_card_cache->reset_card_counts(r); 4759 } 4760 4761 if (!evacuation_failed) { 4762 r->rem_set()->clear_locked(); 4763 } 4764 } 4765 4766 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure { 4767 private: 4768 size_t _cur_idx; 4769 WorkItem* _work_items; 4770 public: 4771 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { } 4772 4773 virtual bool doHeapRegion(HeapRegion* r) { 4774 _work_items[_cur_idx++] = WorkItem(r); 4775 return false; 4776 } 4777 }; 4778 4779 void prepare_work() { 4780 G1PrepareFreeCollectionSetClosure cl(_work_items); 4781 _collection_set->iterate(&cl); 4782 } 4783 4784 void complete_work() { 4785 _cl.complete_work(); 4786 4787 G1Policy* policy = G1CollectedHeap::heap()->g1_policy(); 4788 policy->record_max_rs_lengths(_rs_lengths); 4789 policy->cset_regions_freed(); 4790 } 4791 public: 4792 G1FreeCollectionSetTask(G1CollectionSet* collection_set, EvacuationInfo* evacuation_info, const size_t* surviving_young_words) : 4793 AbstractGangTask("G1 Free Collection Set"), 4794 _cl(evacuation_info, surviving_young_words), 4795 _collection_set(collection_set), 4796 _surviving_young_words(surviving_young_words), 4797 _serial_work_claim(0), 4798 _rs_lengths(0), 4799 _parallel_work_claim(0), 4800 _num_work_items(collection_set->region_length()), 4801 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) { 4802 prepare_work(); 4803 } 4804 4805 ~G1FreeCollectionSetTask() { 4806 complete_work(); 4807 FREE_C_HEAP_ARRAY(WorkItem, _work_items); 4808 } 4809 4810 // Chunk size for work distribution. The chosen value has been determined experimentally 4811 // to be a good tradeoff between overhead and achievable parallelism. 4812 static uint chunk_size() { return 32; } 4813 4814 virtual void work(uint worker_id) { 4815 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times(); 4816 4817 // Claim serial work. 4818 if (_serial_work_claim == 0) { 4819 jint value = Atomic::add(1, &_serial_work_claim) - 1; 4820 if (value == 0) { 4821 double serial_time = os::elapsedTime(); 4822 do_serial_work(); 4823 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0); 4824 } 4825 } 4826 4827 // Start parallel work. 4828 double young_time = 0.0; 4829 bool has_young_time = false; 4830 double non_young_time = 0.0; 4831 bool has_non_young_time = false; 4832 4833 while (true) { 4834 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim); 4835 size_t cur = end - chunk_size(); 4836 4837 if (cur >= _num_work_items) { 4838 break; 4839 } 4840 4841 double start_time = os::elapsedTime(); 4842 4843 end = MIN2(end, _num_work_items); 4844 4845 for (; cur < end; cur++) { 4846 bool is_young = _work_items[cur].is_young; 4847 4848 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed); 4849 4850 double end_time = os::elapsedTime(); 4851 double time_taken = end_time - start_time; 4852 if (is_young) { 4853 young_time += time_taken; 4854 has_young_time = true; 4855 } else { 4856 non_young_time += time_taken; 4857 has_non_young_time = true; 4858 } 4859 start_time = end_time; 4860 } 4861 } 4862 4863 if (has_young_time) { 4864 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time); 4865 } 4866 if (has_non_young_time) { 4867 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, young_time); 4868 } 4869 } 4870 }; 4871 4872 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) { 4873 _eden.clear(); 4874 4875 double free_cset_start_time = os::elapsedTime(); 4876 4877 { 4878 uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U); 4879 uint const num_workers = MIN2(workers()->active_workers(), num_chunks); 4880 4881 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words); 4882 4883 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u", 4884 cl.name(), 4885 num_workers, 4886 _collection_set.region_length()); 4887 workers()->run_task(&cl, num_workers); 4888 } 4889 g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0); 4890 4891 collection_set->clear(); 4892 } 4893 4894 class G1FreeHumongousRegionClosure : public HeapRegionClosure { 4895 private: 4896 FreeRegionList* _free_region_list; 4897 HeapRegionSet* _proxy_set; 4898 uint _humongous_regions_removed; 4899 size_t _freed_bytes; 4900 public: 4901 4902 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) : 4903 _free_region_list(free_region_list), _humongous_regions_removed(0), _freed_bytes(0) { 4904 } 4905 4906 virtual bool doHeapRegion(HeapRegion* r) { 4907 if (!r->is_starts_humongous()) { 4908 return false; 4909 } 4910 4911 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4912 4913 oop obj = (oop)r->bottom(); 4914 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap(); 4915 4916 // The following checks whether the humongous object is live are sufficient. 4917 // The main additional check (in addition to having a reference from the roots 4918 // or the young gen) is whether the humongous object has a remembered set entry. 4919 // 4920 // A humongous object cannot be live if there is no remembered set for it 4921 // because: 4922 // - there can be no references from within humongous starts regions referencing 4923 // the object because we never allocate other objects into them. 4924 // (I.e. there are no intra-region references that may be missed by the 4925 // remembered set) 4926 // - as soon there is a remembered set entry to the humongous starts region 4927 // (i.e. it has "escaped" to an old object) this remembered set entry will stay 4928 // until the end of a concurrent mark. 4929 // 4930 // It is not required to check whether the object has been found dead by marking 4931 // or not, in fact it would prevent reclamation within a concurrent cycle, as 4932 // all objects allocated during that time are considered live. 4933 // SATB marking is even more conservative than the remembered set. 4934 // So if at this point in the collection there is no remembered set entry, 4935 // nobody has a reference to it. 4936 // At the start of collection we flush all refinement logs, and remembered sets 4937 // are completely up-to-date wrt to references to the humongous object. 4938 // 4939 // Other implementation considerations: 4940 // - never consider object arrays at this time because they would pose 4941 // considerable effort for cleaning up the the remembered sets. This is 4942 // required because stale remembered sets might reference locations that 4943 // are currently allocated into. 4944 uint region_idx = r->hrm_index(); 4945 if (!g1h->is_humongous_reclaim_candidate(region_idx) || 4946 !r->rem_set()->is_empty()) { 4947 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", 4948 region_idx, 4949 (size_t)obj->size() * HeapWordSize, 4950 p2i(r->bottom()), 4951 r->rem_set()->occupied(), 4952 r->rem_set()->strong_code_roots_list_length(), 4953 next_bitmap->isMarked(r->bottom()), 4954 g1h->is_humongous_reclaim_candidate(region_idx), 4955 obj->is_typeArray() 4956 ); 4957 return false; 4958 } 4959 4960 guarantee(obj->is_typeArray(), 4961 "Only eagerly reclaiming type arrays is supported, but the object " 4962 PTR_FORMAT " is not.", p2i(r->bottom())); 4963 4964 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", 4965 region_idx, 4966 (size_t)obj->size() * HeapWordSize, 4967 p2i(r->bottom()), 4968 r->rem_set()->occupied(), 4969 r->rem_set()->strong_code_roots_list_length(), 4970 next_bitmap->isMarked(r->bottom()), 4971 g1h->is_humongous_reclaim_candidate(region_idx), 4972 obj->is_typeArray() 4973 ); 4974 4975 // Need to clear mark bit of the humongous object if already set. 4976 if (next_bitmap->isMarked(r->bottom())) { 4977 next_bitmap->clear(r->bottom()); 4978 } 4979 do { 4980 HeapRegion* next = g1h->next_region_in_humongous(r); 4981 _freed_bytes += r->used(); 4982 r->set_containing_set(NULL); 4983 _humongous_regions_removed++; 4984 g1h->free_humongous_region(r, _free_region_list, false /* skip_remset */ ); 4985 r = next; 4986 } while (r != NULL); 4987 4988 return false; 4989 } 4990 4991 uint humongous_free_count() { 4992 return _humongous_regions_removed; 4993 } 4994 4995 size_t bytes_freed() const { 4996 return _freed_bytes; 4997 } 4998 }; 4999 5000 void G1CollectedHeap::eagerly_reclaim_humongous_regions() { 5001 assert_at_safepoint(true); 5002 5003 if (!G1EagerReclaimHumongousObjects || 5004 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) { 5005 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0); 5006 return; 5007 } 5008 5009 double start_time = os::elapsedTime(); 5010 5011 FreeRegionList local_cleanup_list("Local Humongous Cleanup List"); 5012 5013 G1FreeHumongousRegionClosure cl(&local_cleanup_list); 5014 heap_region_iterate(&cl); 5015 5016 remove_from_old_sets(0, cl.humongous_free_count()); 5017 5018 G1HRPrinter* hrp = hr_printer(); 5019 if (hrp->is_active()) { 5020 FreeRegionListIterator iter(&local_cleanup_list); 5021 while (iter.more_available()) { 5022 HeapRegion* hr = iter.get_next(); 5023 hrp->cleanup(hr); 5024 } 5025 } 5026 5027 prepend_to_freelist(&local_cleanup_list); 5028 decrement_summary_bytes(cl.bytes_freed()); 5029 5030 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0, 5031 cl.humongous_free_count()); 5032 } 5033 5034 class G1AbandonCollectionSetClosure : public HeapRegionClosure { 5035 public: 5036 virtual bool doHeapRegion(HeapRegion* r) { 5037 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index()); 5038 G1CollectedHeap::heap()->clear_in_cset(r); 5039 r->set_young_index_in_cset(-1); 5040 return false; 5041 } 5042 }; 5043 5044 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) { 5045 G1AbandonCollectionSetClosure cl; 5046 collection_set->iterate(&cl); 5047 5048 collection_set->clear(); 5049 collection_set->stop_incremental_building(); 5050 } 5051 5052 void G1CollectedHeap::set_free_regions_coming() { 5053 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : setting free regions coming"); 5054 5055 assert(!free_regions_coming(), "pre-condition"); 5056 _free_regions_coming = true; 5057 } 5058 5059 void G1CollectedHeap::reset_free_regions_coming() { 5060 assert(free_regions_coming(), "pre-condition"); 5061 5062 { 5063 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 5064 _free_regions_coming = false; 5065 SecondaryFreeList_lock->notify_all(); 5066 } 5067 5068 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : reset free regions coming"); 5069 } 5070 5071 void G1CollectedHeap::wait_while_free_regions_coming() { 5072 // Most of the time we won't have to wait, so let's do a quick test 5073 // first before we take the lock. 5074 if (!free_regions_coming()) { 5075 return; 5076 } 5077 5078 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : waiting for free regions"); 5079 5080 { 5081 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 5082 while (free_regions_coming()) { 5083 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 5084 } 5085 } 5086 5087 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : done waiting for free regions"); 5088 } 5089 5090 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) { 5091 return _allocator->is_retained_old_region(hr); 5092 } 5093 5094 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 5095 _eden.add(hr); 5096 _g1_policy->set_region_eden(hr); 5097 } 5098 5099 #ifdef ASSERT 5100 5101 class NoYoungRegionsClosure: public HeapRegionClosure { 5102 private: 5103 bool _success; 5104 public: 5105 NoYoungRegionsClosure() : _success(true) { } 5106 bool doHeapRegion(HeapRegion* r) { 5107 if (r->is_young()) { 5108 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young", 5109 p2i(r->bottom()), p2i(r->end())); 5110 _success = false; 5111 } 5112 return false; 5113 } 5114 bool success() { return _success; } 5115 }; 5116 5117 bool G1CollectedHeap::check_young_list_empty() { 5118 bool ret = (young_regions_count() == 0); 5119 5120 NoYoungRegionsClosure closure; 5121 heap_region_iterate(&closure); 5122 ret = ret && closure.success(); 5123 5124 return ret; 5125 } 5126 5127 #endif // ASSERT 5128 5129 class TearDownRegionSetsClosure : public HeapRegionClosure { 5130 private: 5131 HeapRegionSet *_old_set; 5132 5133 public: 5134 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { } 5135 5136 bool doHeapRegion(HeapRegion* r) { 5137 if (r->is_old()) { 5138 _old_set->remove(r); 5139 } else if(r->is_young()) { 5140 r->uninstall_surv_rate_group(); 5141 } else { 5142 // We ignore free regions, we'll empty the free list afterwards. 5143 // We ignore humongous regions, we're not tearing down the 5144 // humongous regions set. 5145 assert(r->is_free() || r->is_humongous(), 5146 "it cannot be another type"); 5147 } 5148 return false; 5149 } 5150 5151 ~TearDownRegionSetsClosure() { 5152 assert(_old_set->is_empty(), "post-condition"); 5153 } 5154 }; 5155 5156 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) { 5157 assert_at_safepoint(true /* should_be_vm_thread */); 5158 5159 if (!free_list_only) { 5160 TearDownRegionSetsClosure cl(&_old_set); 5161 heap_region_iterate(&cl); 5162 5163 // Note that emptying the _young_list is postponed and instead done as 5164 // the first step when rebuilding the regions sets again. The reason for 5165 // this is that during a full GC string deduplication needs to know if 5166 // a collected region was young or old when the full GC was initiated. 5167 } 5168 _hrm.remove_all_free_regions(); 5169 } 5170 5171 void G1CollectedHeap::increase_used(size_t bytes) { 5172 _summary_bytes_used += bytes; 5173 } 5174 5175 void G1CollectedHeap::decrease_used(size_t bytes) { 5176 assert(_summary_bytes_used >= bytes, 5177 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT, 5178 _summary_bytes_used, bytes); 5179 _summary_bytes_used -= bytes; 5180 } 5181 5182 void G1CollectedHeap::set_used(size_t bytes) { 5183 _summary_bytes_used = bytes; 5184 } 5185 5186 class RebuildRegionSetsClosure : public HeapRegionClosure { 5187 private: 5188 bool _free_list_only; 5189 HeapRegionSet* _old_set; 5190 HeapRegionManager* _hrm; 5191 size_t _total_used; 5192 5193 public: 5194 RebuildRegionSetsClosure(bool free_list_only, 5195 HeapRegionSet* old_set, HeapRegionManager* hrm) : 5196 _free_list_only(free_list_only), 5197 _old_set(old_set), _hrm(hrm), _total_used(0) { 5198 assert(_hrm->num_free_regions() == 0, "pre-condition"); 5199 if (!free_list_only) { 5200 assert(_old_set->is_empty(), "pre-condition"); 5201 } 5202 } 5203 5204 bool doHeapRegion(HeapRegion* r) { 5205 if (r->is_empty()) { 5206 // Add free regions to the free list 5207 r->set_free(); 5208 r->set_allocation_context(AllocationContext::system()); 5209 _hrm->insert_into_free_list(r); 5210 } else if (!_free_list_only) { 5211 5212 if (r->is_humongous()) { 5213 // We ignore humongous regions. We left the humongous set unchanged. 5214 } else { 5215 assert(r->is_young() || r->is_free() || r->is_old(), "invariant"); 5216 // We now consider all regions old, so register as such. Leave 5217 // archive regions set that way, however, while still adding 5218 // them to the old set. 5219 if (!r->is_archive()) { 5220 r->set_old(); 5221 } 5222 _old_set->add(r); 5223 } 5224 _total_used += r->used(); 5225 } 5226 5227 return false; 5228 } 5229 5230 size_t total_used() { 5231 return _total_used; 5232 } 5233 }; 5234 5235 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { 5236 assert_at_safepoint(true /* should_be_vm_thread */); 5237 5238 if (!free_list_only) { 5239 _eden.clear(); 5240 _survivor.clear(); 5241 } 5242 5243 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm); 5244 heap_region_iterate(&cl); 5245 5246 if (!free_list_only) { 5247 set_used(cl.total_used()); 5248 if (_archive_allocator != NULL) { 5249 _archive_allocator->clear_used(); 5250 } 5251 } 5252 assert(used_unlocked() == recalculate_used(), 5253 "inconsistent used_unlocked(), " 5254 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT, 5255 used_unlocked(), recalculate_used()); 5256 } 5257 5258 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) { 5259 _refine_cte_cl->set_concurrent(concurrent); 5260 } 5261 5262 bool G1CollectedHeap::is_in_closed_subset(const void* p) const { 5263 HeapRegion* hr = heap_region_containing(p); 5264 return hr->is_in(p); 5265 } 5266 5267 // Methods for the mutator alloc region 5268 5269 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 5270 bool force) { 5271 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 5272 assert(!force || g1_policy()->can_expand_young_list(), 5273 "if force is true we should be able to expand the young list"); 5274 bool should_allocate = g1_policy()->should_allocate_mutator_region(); 5275 if (force || should_allocate) { 5276 HeapRegion* new_alloc_region = new_region(word_size, 5277 false /* is_old */, 5278 false /* do_expand */); 5279 if (new_alloc_region != NULL) { 5280 set_region_short_lived_locked(new_alloc_region); 5281 _hr_printer.alloc(new_alloc_region, !should_allocate); 5282 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region); 5283 return new_alloc_region; 5284 } 5285 } 5286 return NULL; 5287 } 5288 5289 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 5290 size_t allocated_bytes) { 5291 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 5292 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden"); 5293 5294 collection_set()->add_eden_region(alloc_region); 5295 increase_used(allocated_bytes); 5296 _hr_printer.retire(alloc_region); 5297 // We update the eden sizes here, when the region is retired, 5298 // instead of when it's allocated, since this is the point that its 5299 // used space has been recored in _summary_bytes_used. 5300 g1mm()->update_eden_size(); 5301 } 5302 5303 // Methods for the GC alloc regions 5304 5305 bool G1CollectedHeap::has_more_regions(InCSetState dest) { 5306 if (dest.is_old()) { 5307 return true; 5308 } else { 5309 return survivor_regions_count() < g1_policy()->max_survivor_regions(); 5310 } 5311 } 5312 5313 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) { 5314 assert(FreeList_lock->owned_by_self(), "pre-condition"); 5315 5316 if (!has_more_regions(dest)) { 5317 return NULL; 5318 } 5319 5320 const bool is_survivor = dest.is_young(); 5321 5322 HeapRegion* new_alloc_region = new_region(word_size, 5323 !is_survivor, 5324 true /* do_expand */); 5325 if (new_alloc_region != NULL) { 5326 // We really only need to do this for old regions given that we 5327 // should never scan survivors. But it doesn't hurt to do it 5328 // for survivors too. 5329 new_alloc_region->record_timestamp(); 5330 if (is_survivor) { 5331 new_alloc_region->set_survivor(); 5332 _survivor.add(new_alloc_region); 5333 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region); 5334 } else { 5335 new_alloc_region->set_old(); 5336 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region); 5337 } 5338 _hr_printer.alloc(new_alloc_region); 5339 bool during_im = collector_state()->during_initial_mark_pause(); 5340 new_alloc_region->note_start_of_copying(during_im); 5341 return new_alloc_region; 5342 } 5343 return NULL; 5344 } 5345 5346 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 5347 size_t allocated_bytes, 5348 InCSetState dest) { 5349 bool during_im = collector_state()->during_initial_mark_pause(); 5350 alloc_region->note_end_of_copying(during_im); 5351 g1_policy()->record_bytes_copied_during_gc(allocated_bytes); 5352 if (dest.is_old()) { 5353 _old_set.add(alloc_region); 5354 } 5355 _hr_printer.retire(alloc_region); 5356 } 5357 5358 HeapRegion* G1CollectedHeap::alloc_highest_free_region() { 5359 bool expanded = false; 5360 uint index = _hrm.find_highest_free(&expanded); 5361 5362 if (index != G1_NO_HRM_INDEX) { 5363 if (expanded) { 5364 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B", 5365 HeapRegion::GrainWords * HeapWordSize); 5366 } 5367 _hrm.allocate_free_regions_starting_at(index, 1); 5368 return region_at(index); 5369 } 5370 return NULL; 5371 } 5372 5373 // Optimized nmethod scanning 5374 5375 class RegisterNMethodOopClosure: public OopClosure { 5376 G1CollectedHeap* _g1h; 5377 nmethod* _nm; 5378 5379 template <class T> void do_oop_work(T* p) { 5380 T heap_oop = oopDesc::load_heap_oop(p); 5381 if (!oopDesc::is_null(heap_oop)) { 5382 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 5383 HeapRegion* hr = _g1h->heap_region_containing(obj); 5384 assert(!hr->is_continues_humongous(), 5385 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 5386 " starting at " HR_FORMAT, 5387 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 5388 5389 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries. 5390 hr->add_strong_code_root_locked(_nm); 5391 } 5392 } 5393 5394 public: 5395 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 5396 _g1h(g1h), _nm(nm) {} 5397 5398 void do_oop(oop* p) { do_oop_work(p); } 5399 void do_oop(narrowOop* p) { do_oop_work(p); } 5400 }; 5401 5402 class UnregisterNMethodOopClosure: public OopClosure { 5403 G1CollectedHeap* _g1h; 5404 nmethod* _nm; 5405 5406 template <class T> void do_oop_work(T* p) { 5407 T heap_oop = oopDesc::load_heap_oop(p); 5408 if (!oopDesc::is_null(heap_oop)) { 5409 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 5410 HeapRegion* hr = _g1h->heap_region_containing(obj); 5411 assert(!hr->is_continues_humongous(), 5412 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 5413 " starting at " HR_FORMAT, 5414 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 5415 5416 hr->remove_strong_code_root(_nm); 5417 } 5418 } 5419 5420 public: 5421 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 5422 _g1h(g1h), _nm(nm) {} 5423 5424 void do_oop(oop* p) { do_oop_work(p); } 5425 void do_oop(narrowOop* p) { do_oop_work(p); } 5426 }; 5427 5428 void G1CollectedHeap::register_nmethod(nmethod* nm) { 5429 CollectedHeap::register_nmethod(nm); 5430 5431 guarantee(nm != NULL, "sanity"); 5432 RegisterNMethodOopClosure reg_cl(this, nm); 5433 nm->oops_do(®_cl); 5434 } 5435 5436 void G1CollectedHeap::unregister_nmethod(nmethod* nm) { 5437 CollectedHeap::unregister_nmethod(nm); 5438 5439 guarantee(nm != NULL, "sanity"); 5440 UnregisterNMethodOopClosure reg_cl(this, nm); 5441 nm->oops_do(®_cl, true); 5442 } 5443 5444 void G1CollectedHeap::purge_code_root_memory() { 5445 double purge_start = os::elapsedTime(); 5446 G1CodeRootSet::purge(); 5447 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0; 5448 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms); 5449 } 5450 5451 class RebuildStrongCodeRootClosure: public CodeBlobClosure { 5452 G1CollectedHeap* _g1h; 5453 5454 public: 5455 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) : 5456 _g1h(g1h) {} 5457 5458 void do_code_blob(CodeBlob* cb) { 5459 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL; 5460 if (nm == NULL) { 5461 return; 5462 } 5463 5464 if (ScavengeRootsInCode) { 5465 _g1h->register_nmethod(nm); 5466 } 5467 } 5468 }; 5469 5470 void G1CollectedHeap::rebuild_strong_code_roots() { 5471 RebuildStrongCodeRootClosure blob_cl(this); 5472 CodeCache::blobs_do(&blob_cl); 5473 }