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/concurrentMarkThread.inline.hpp" 33 #include "gc/g1/g1Allocator.inline.hpp" 34 #include "gc/g1/g1CollectedHeap.inline.hpp" 35 #include "gc/g1/g1CollectionSet.hpp" 36 #include "gc/g1/g1CollectorPolicy.hpp" 37 #include "gc/g1/g1CollectorState.hpp" 38 #include "gc/g1/g1ConcurrentRefine.hpp" 39 #include "gc/g1/g1ConcurrentRefineThread.hpp" 40 #include "gc/g1/g1EvacStats.inline.hpp" 41 #include "gc/g1/g1FullCollector.hpp" 42 #include "gc/g1/g1GCPhaseTimes.hpp" 43 #include "gc/g1/g1HeapSizingPolicy.hpp" 44 #include "gc/g1/g1HeapTransition.hpp" 45 #include "gc/g1/g1HeapVerifier.hpp" 46 #include "gc/g1/g1HotCardCache.hpp" 47 #include "gc/g1/g1MemoryPool.hpp" 48 #include "gc/g1/g1OopClosures.inline.hpp" 49 #include "gc/g1/g1ParScanThreadState.inline.hpp" 50 #include "gc/g1/g1Policy.hpp" 51 #include "gc/g1/g1RegionToSpaceMapper.hpp" 52 #include "gc/g1/g1RemSet.hpp" 53 #include "gc/g1/g1RootClosures.hpp" 54 #include "gc/g1/g1RootProcessor.hpp" 55 #include "gc/g1/g1StringDedup.hpp" 56 #include "gc/g1/g1YCTypes.hpp" 57 #include "gc/g1/g1YoungRemSetSamplingThread.hpp" 58 #include "gc/g1/heapRegion.inline.hpp" 59 #include "gc/g1/heapRegionRemSet.hpp" 60 #include "gc/g1/heapRegionSet.inline.hpp" 61 #include "gc/g1/vm_operations_g1.hpp" 62 #include "gc/shared/gcHeapSummary.hpp" 63 #include "gc/shared/gcId.hpp" 64 #include "gc/shared/gcLocker.inline.hpp" 65 #include "gc/shared/gcTimer.hpp" 66 #include "gc/shared/gcTrace.hpp" 67 #include "gc/shared/gcTraceTime.inline.hpp" 68 #include "gc/shared/generationSpec.hpp" 69 #include "gc/shared/isGCActiveMark.hpp" 70 #include "gc/shared/preservedMarks.inline.hpp" 71 #include "gc/shared/suspendibleThreadSet.hpp" 72 #include "gc/shared/referenceProcessor.inline.hpp" 73 #include "gc/shared/taskqueue.inline.hpp" 74 #include "gc/shared/weakProcessor.hpp" 75 #include "logging/log.hpp" 76 #include "memory/allocation.hpp" 77 #include "memory/iterator.hpp" 78 #include "memory/resourceArea.hpp" 79 #include "oops/oop.inline.hpp" 80 #include "prims/resolvedMethodTable.hpp" 81 #include "runtime/atomic.hpp" 82 #include "runtime/init.hpp" 83 #include "runtime/orderAccess.inline.hpp" 84 #include "runtime/threadSMR.hpp" 85 #include "runtime/vmThread.hpp" 86 #include "utilities/align.hpp" 87 #include "utilities/globalDefinitions.hpp" 88 #include "utilities/stack.inline.hpp" 89 90 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0; 91 92 // INVARIANTS/NOTES 93 // 94 // All allocation activity covered by the G1CollectedHeap interface is 95 // serialized by acquiring the HeapLock. This happens in mem_allocate 96 // and allocate_new_tlab, which are the "entry" points to the 97 // allocation code from the rest of the JVM. (Note that this does not 98 // apply to TLAB allocation, which is not part of this interface: it 99 // is done by clients of this interface.) 100 101 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure { 102 private: 103 size_t _num_dirtied; 104 G1CollectedHeap* _g1h; 105 G1SATBCardTableLoggingModRefBS* _g1_bs; 106 107 HeapRegion* region_for_card(jbyte* card_ptr) const { 108 return _g1h->heap_region_containing(_g1_bs->addr_for(card_ptr)); 109 } 110 111 bool will_become_free(HeapRegion* hr) const { 112 // A region will be freed by free_collection_set if the region is in the 113 // collection set and has not had an evacuation failure. 114 return _g1h->is_in_cset(hr) && !hr->evacuation_failed(); 115 } 116 117 public: 118 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(), 119 _num_dirtied(0), _g1h(g1h), _g1_bs(g1h->g1_barrier_set()) { } 120 121 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 122 HeapRegion* hr = region_for_card(card_ptr); 123 124 // Should only dirty cards in regions that won't be freed. 125 if (!will_become_free(hr)) { 126 *card_ptr = CardTableModRefBS::dirty_card_val(); 127 _num_dirtied++; 128 } 129 130 return true; 131 } 132 133 size_t num_dirtied() const { return _num_dirtied; } 134 }; 135 136 137 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) { 138 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions); 139 } 140 141 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) { 142 // The from card cache is not the memory that is actually committed. So we cannot 143 // take advantage of the zero_filled parameter. 144 reset_from_card_cache(start_idx, num_regions); 145 } 146 147 148 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index, 149 MemRegion mr) { 150 return new HeapRegion(hrs_index, bot(), mr); 151 } 152 153 // Private methods. 154 155 HeapRegion* 156 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) { 157 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 158 while (!_secondary_free_list.is_empty() || free_regions_coming()) { 159 if (!_secondary_free_list.is_empty()) { 160 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : " 161 "secondary_free_list has %u entries", 162 _secondary_free_list.length()); 163 // It looks as if there are free regions available on the 164 // secondary_free_list. Let's move them to the free_list and try 165 // again to allocate from it. 166 append_secondary_free_list(); 167 168 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not " 169 "empty we should have moved at least one entry to the free_list"); 170 HeapRegion* res = _hrm.allocate_free_region(is_old); 171 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : " 172 "allocated " HR_FORMAT " from secondary_free_list", 173 HR_FORMAT_PARAMS(res)); 174 return res; 175 } 176 177 // Wait here until we get notified either when (a) there are no 178 // more free regions coming or (b) some regions have been moved on 179 // the secondary_free_list. 180 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 181 } 182 183 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : " 184 "could not allocate from secondary_free_list"); 185 return NULL; 186 } 187 188 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) { 189 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords, 190 "the only time we use this to allocate a humongous region is " 191 "when we are allocating a single humongous region"); 192 193 HeapRegion* res; 194 if (G1StressConcRegionFreeing) { 195 if (!_secondary_free_list.is_empty()) { 196 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : " 197 "forced to look at the secondary_free_list"); 198 res = new_region_try_secondary_free_list(is_old); 199 if (res != NULL) { 200 return res; 201 } 202 } 203 } 204 205 res = _hrm.allocate_free_region(is_old); 206 207 if (res == NULL) { 208 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : " 209 "res == NULL, trying the secondary_free_list"); 210 res = new_region_try_secondary_free_list(is_old); 211 } 212 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) { 213 // Currently, only attempts to allocate GC alloc regions set 214 // do_expand to true. So, we should only reach here during a 215 // safepoint. If this assumption changes we might have to 216 // reconsider the use of _expand_heap_after_alloc_failure. 217 assert(SafepointSynchronize::is_at_safepoint(), "invariant"); 218 219 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B", 220 word_size * HeapWordSize); 221 222 if (expand(word_size * HeapWordSize)) { 223 // Given that expand() succeeded in expanding the heap, and we 224 // always expand the heap by an amount aligned to the heap 225 // region size, the free list should in theory not be empty. 226 // In either case allocate_free_region() will check for NULL. 227 res = _hrm.allocate_free_region(is_old); 228 } else { 229 _expand_heap_after_alloc_failure = false; 230 } 231 } 232 return res; 233 } 234 235 HeapWord* 236 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first, 237 uint num_regions, 238 size_t word_size, 239 AllocationContext_t context) { 240 assert(first != G1_NO_HRM_INDEX, "pre-condition"); 241 assert(is_humongous(word_size), "word_size should be humongous"); 242 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition"); 243 244 // Index of last region in the series. 245 uint last = first + num_regions - 1; 246 247 // We need to initialize the region(s) we just discovered. This is 248 // a bit tricky given that it can happen concurrently with 249 // refinement threads refining cards on these regions and 250 // potentially wanting to refine the BOT as they are scanning 251 // those cards (this can happen shortly after a cleanup; see CR 252 // 6991377). So we have to set up the region(s) carefully and in 253 // a specific order. 254 255 // The word size sum of all the regions we will allocate. 256 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords; 257 assert(word_size <= word_size_sum, "sanity"); 258 259 // This will be the "starts humongous" region. 260 HeapRegion* first_hr = region_at(first); 261 // The header of the new object will be placed at the bottom of 262 // the first region. 263 HeapWord* new_obj = first_hr->bottom(); 264 // This will be the new top of the new object. 265 HeapWord* obj_top = new_obj + word_size; 266 267 // First, we need to zero the header of the space that we will be 268 // allocating. When we update top further down, some refinement 269 // threads might try to scan the region. By zeroing the header we 270 // ensure that any thread that will try to scan the region will 271 // come across the zero klass word and bail out. 272 // 273 // NOTE: It would not have been correct to have used 274 // CollectedHeap::fill_with_object() and make the space look like 275 // an int array. The thread that is doing the allocation will 276 // later update the object header to a potentially different array 277 // type and, for a very short period of time, the klass and length 278 // fields will be inconsistent. This could cause a refinement 279 // thread to calculate the object size incorrectly. 280 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0); 281 282 // Next, pad out the unused tail of the last region with filler 283 // objects, for improved usage accounting. 284 // How many words we use for filler objects. 285 size_t word_fill_size = word_size_sum - word_size; 286 287 // How many words memory we "waste" which cannot hold a filler object. 288 size_t words_not_fillable = 0; 289 290 if (word_fill_size >= min_fill_size()) { 291 fill_with_objects(obj_top, word_fill_size); 292 } else if (word_fill_size > 0) { 293 // We have space to fill, but we cannot fit an object there. 294 words_not_fillable = word_fill_size; 295 word_fill_size = 0; 296 } 297 298 // We will set up the first region as "starts humongous". This 299 // will also update the BOT covering all the regions to reflect 300 // that there is a single object that starts at the bottom of the 301 // first region. 302 first_hr->set_starts_humongous(obj_top, word_fill_size); 303 first_hr->set_allocation_context(context); 304 // Then, if there are any, we will set up the "continues 305 // humongous" regions. 306 HeapRegion* hr = NULL; 307 for (uint i = first + 1; i <= last; ++i) { 308 hr = region_at(i); 309 hr->set_continues_humongous(first_hr); 310 hr->set_allocation_context(context); 311 } 312 313 // Up to this point no concurrent thread would have been able to 314 // do any scanning on any region in this series. All the top 315 // fields still point to bottom, so the intersection between 316 // [bottom,top] and [card_start,card_end] will be empty. Before we 317 // update the top fields, we'll do a storestore to make sure that 318 // no thread sees the update to top before the zeroing of the 319 // object header and the BOT initialization. 320 OrderAccess::storestore(); 321 322 // Now, we will update the top fields of the "continues humongous" 323 // regions except the last one. 324 for (uint i = first; i < last; ++i) { 325 hr = region_at(i); 326 hr->set_top(hr->end()); 327 } 328 329 hr = region_at(last); 330 // If we cannot fit a filler object, we must set top to the end 331 // of the humongous object, otherwise we cannot iterate the heap 332 // and the BOT will not be complete. 333 hr->set_top(hr->end() - words_not_fillable); 334 335 assert(hr->bottom() < obj_top && obj_top <= hr->end(), 336 "obj_top should be in last region"); 337 338 _verifier->check_bitmaps("Humongous Region Allocation", first_hr); 339 340 assert(words_not_fillable == 0 || 341 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(), 342 "Miscalculation in humongous allocation"); 343 344 increase_used((word_size_sum - words_not_fillable) * HeapWordSize); 345 346 for (uint i = first; i <= last; ++i) { 347 hr = region_at(i); 348 _humongous_set.add(hr); 349 _hr_printer.alloc(hr); 350 } 351 352 return new_obj; 353 } 354 355 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) { 356 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size); 357 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords; 358 } 359 360 // If could fit into free regions w/o expansion, try. 361 // Otherwise, if can expand, do so. 362 // Otherwise, if using ex regions might help, try with ex given back. 363 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) { 364 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 365 366 _verifier->verify_region_sets_optional(); 367 368 uint first = G1_NO_HRM_INDEX; 369 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size); 370 371 if (obj_regions == 1) { 372 // Only one region to allocate, try to use a fast path by directly allocating 373 // from the free lists. Do not try to expand here, we will potentially do that 374 // later. 375 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */); 376 if (hr != NULL) { 377 first = hr->hrm_index(); 378 } 379 } else { 380 // We can't allocate humongous regions spanning more than one region while 381 // cleanupComplete() is running, since some of the regions we find to be 382 // empty might not yet be added to the free list. It is not straightforward 383 // to know in which list they are on so that we can remove them. We only 384 // need to do this if we need to allocate more than one region to satisfy the 385 // current humongous allocation request. If we are only allocating one region 386 // we use the one-region region allocation code (see above), that already 387 // potentially waits for regions from the secondary free list. 388 wait_while_free_regions_coming(); 389 append_secondary_free_list_if_not_empty_with_lock(); 390 391 // Policy: Try only empty regions (i.e. already committed first). Maybe we 392 // are lucky enough to find some. 393 first = _hrm.find_contiguous_only_empty(obj_regions); 394 if (first != G1_NO_HRM_INDEX) { 395 _hrm.allocate_free_regions_starting_at(first, obj_regions); 396 } 397 } 398 399 if (first == G1_NO_HRM_INDEX) { 400 // Policy: We could not find enough regions for the humongous object in the 401 // free list. Look through the heap to find a mix of free and uncommitted regions. 402 // If so, try expansion. 403 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions); 404 if (first != G1_NO_HRM_INDEX) { 405 // We found something. Make sure these regions are committed, i.e. expand 406 // the heap. Alternatively we could do a defragmentation GC. 407 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B", 408 word_size * HeapWordSize); 409 410 _hrm.expand_at(first, obj_regions, workers()); 411 g1_policy()->record_new_heap_size(num_regions()); 412 413 #ifdef ASSERT 414 for (uint i = first; i < first + obj_regions; ++i) { 415 HeapRegion* hr = region_at(i); 416 assert(hr->is_free(), "sanity"); 417 assert(hr->is_empty(), "sanity"); 418 assert(is_on_master_free_list(hr), "sanity"); 419 } 420 #endif 421 _hrm.allocate_free_regions_starting_at(first, obj_regions); 422 } else { 423 // Policy: Potentially trigger a defragmentation GC. 424 } 425 } 426 427 HeapWord* result = NULL; 428 if (first != G1_NO_HRM_INDEX) { 429 result = humongous_obj_allocate_initialize_regions(first, obj_regions, 430 word_size, context); 431 assert(result != NULL, "it should always return a valid result"); 432 433 // A successful humongous object allocation changes the used space 434 // information of the old generation so we need to recalculate the 435 // sizes and update the jstat counters here. 436 g1mm()->update_sizes(); 437 } 438 439 _verifier->verify_region_sets_optional(); 440 441 return result; 442 } 443 444 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) { 445 assert_heap_not_locked_and_not_at_safepoint(); 446 assert(!is_humongous(word_size), "we do not allow humongous TLABs"); 447 448 uint dummy_gc_count_before; 449 uint dummy_gclocker_retry_count = 0; 450 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count); 451 } 452 453 HeapWord* 454 G1CollectedHeap::mem_allocate(size_t word_size, 455 bool* gc_overhead_limit_was_exceeded) { 456 assert_heap_not_locked_and_not_at_safepoint(); 457 458 // Loop until the allocation is satisfied, or unsatisfied after GC. 459 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 460 uint gc_count_before; 461 462 HeapWord* result = NULL; 463 if (!is_humongous(word_size)) { 464 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count); 465 } else { 466 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count); 467 } 468 if (result != NULL) { 469 return result; 470 } 471 472 // Create the garbage collection operation... 473 VM_G1CollectForAllocation op(gc_count_before, word_size); 474 op.set_allocation_context(AllocationContext::current()); 475 476 // ...and get the VM thread to execute it. 477 VMThread::execute(&op); 478 479 if (op.prologue_succeeded() && op.pause_succeeded()) { 480 // If the operation was successful we'll return the result even 481 // if it is NULL. If the allocation attempt failed immediately 482 // after a Full GC, it's unlikely we'll be able to allocate now. 483 HeapWord* result = op.result(); 484 if (result != NULL && !is_humongous(word_size)) { 485 // Allocations that take place on VM operations do not do any 486 // card dirtying and we have to do it here. We only have to do 487 // this for non-humongous allocations, though. 488 dirty_young_block(result, word_size); 489 } 490 return result; 491 } else { 492 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 493 return NULL; 494 } 495 assert(op.result() == NULL, 496 "the result should be NULL if the VM op did not succeed"); 497 } 498 499 // Give a warning if we seem to be looping forever. 500 if ((QueuedAllocationWarningCount > 0) && 501 (try_count % QueuedAllocationWarningCount == 0)) { 502 log_warning(gc)("G1CollectedHeap::mem_allocate retries %d times", try_count); 503 } 504 } 505 506 ShouldNotReachHere(); 507 return NULL; 508 } 509 510 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size, 511 AllocationContext_t context, 512 uint* gc_count_before_ret, 513 uint* gclocker_retry_count_ret) { 514 // Make sure you read the note in attempt_allocation_humongous(). 515 516 assert_heap_not_locked_and_not_at_safepoint(); 517 assert(!is_humongous(word_size), "attempt_allocation_slow() should not " 518 "be called for humongous allocation requests"); 519 520 // We should only get here after the first-level allocation attempt 521 // (attempt_allocation()) failed to allocate. 522 523 // We will loop until a) we manage to successfully perform the 524 // allocation or b) we successfully schedule a collection which 525 // fails to perform the allocation. b) is the only case when we'll 526 // return NULL. 527 HeapWord* result = NULL; 528 for (int try_count = 1; /* we'll return */; try_count += 1) { 529 bool should_try_gc; 530 uint gc_count_before; 531 532 { 533 MutexLockerEx x(Heap_lock); 534 result = _allocator->attempt_allocation_locked(word_size, context); 535 if (result != NULL) { 536 return result; 537 } 538 539 if (GCLocker::is_active_and_needs_gc()) { 540 if (g1_policy()->can_expand_young_list()) { 541 // No need for an ergo verbose message here, 542 // can_expand_young_list() does this when it returns true. 543 result = _allocator->attempt_allocation_force(word_size, context); 544 if (result != NULL) { 545 return result; 546 } 547 } 548 should_try_gc = false; 549 } else { 550 // The GCLocker may not be active but the GCLocker initiated 551 // GC may not yet have been performed (GCLocker::needs_gc() 552 // returns true). In this case we do not try this GC and 553 // wait until the GCLocker initiated GC is performed, and 554 // then retry the allocation. 555 if (GCLocker::needs_gc()) { 556 should_try_gc = false; 557 } else { 558 // Read the GC count while still holding the Heap_lock. 559 gc_count_before = total_collections(); 560 should_try_gc = true; 561 } 562 } 563 } 564 565 if (should_try_gc) { 566 bool succeeded; 567 result = do_collection_pause(word_size, gc_count_before, &succeeded, 568 GCCause::_g1_inc_collection_pause); 569 if (result != NULL) { 570 assert(succeeded, "only way to get back a non-NULL result"); 571 return result; 572 } 573 574 if (succeeded) { 575 // If we get here we successfully scheduled a collection which 576 // failed to allocate. No point in trying to allocate 577 // further. We'll just return NULL. 578 MutexLockerEx x(Heap_lock); 579 *gc_count_before_ret = total_collections(); 580 return NULL; 581 } 582 } else { 583 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { 584 MutexLockerEx x(Heap_lock); 585 *gc_count_before_ret = total_collections(); 586 return NULL; 587 } 588 // The GCLocker is either active or the GCLocker initiated 589 // GC has not yet been performed. Stall until it is and 590 // then retry the allocation. 591 GCLocker::stall_until_clear(); 592 (*gclocker_retry_count_ret) += 1; 593 } 594 595 // We can reach here if we were unsuccessful in scheduling a 596 // collection (because another thread beat us to it) or if we were 597 // stalled due to the GC locker. In either can we should retry the 598 // allocation attempt in case another thread successfully 599 // performed a collection and reclaimed enough space. We do the 600 // first attempt (without holding the Heap_lock) here and the 601 // follow-on attempt will be at the start of the next loop 602 // iteration (after taking the Heap_lock). 603 result = _allocator->attempt_allocation(word_size, context); 604 if (result != NULL) { 605 return result; 606 } 607 608 // Give a warning if we seem to be looping forever. 609 if ((QueuedAllocationWarningCount > 0) && 610 (try_count % QueuedAllocationWarningCount == 0)) { 611 log_warning(gc)("G1CollectedHeap::attempt_allocation_slow() " 612 "retries %d times", try_count); 613 } 614 } 615 616 ShouldNotReachHere(); 617 return NULL; 618 } 619 620 void G1CollectedHeap::begin_archive_alloc_range(bool open) { 621 assert_at_safepoint(true /* should_be_vm_thread */); 622 if (_archive_allocator == NULL) { 623 _archive_allocator = G1ArchiveAllocator::create_allocator(this, open); 624 } 625 } 626 627 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) { 628 // Allocations in archive regions cannot be of a size that would be considered 629 // humongous even for a minimum-sized region, because G1 region sizes/boundaries 630 // may be different at archive-restore time. 631 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words()); 632 } 633 634 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) { 635 assert_at_safepoint(true /* should_be_vm_thread */); 636 assert(_archive_allocator != NULL, "_archive_allocator not initialized"); 637 if (is_archive_alloc_too_large(word_size)) { 638 return NULL; 639 } 640 return _archive_allocator->archive_mem_allocate(word_size); 641 } 642 643 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges, 644 size_t end_alignment_in_bytes) { 645 assert_at_safepoint(true /* should_be_vm_thread */); 646 assert(_archive_allocator != NULL, "_archive_allocator not initialized"); 647 648 // Call complete_archive to do the real work, filling in the MemRegion 649 // array with the archive regions. 650 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes); 651 delete _archive_allocator; 652 _archive_allocator = NULL; 653 } 654 655 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) { 656 assert(ranges != NULL, "MemRegion array NULL"); 657 assert(count != 0, "No MemRegions provided"); 658 MemRegion reserved = _hrm.reserved(); 659 for (size_t i = 0; i < count; i++) { 660 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) { 661 return false; 662 } 663 } 664 return true; 665 } 666 667 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, 668 size_t count, 669 bool open) { 670 assert(!is_init_completed(), "Expect to be called at JVM init time"); 671 assert(ranges != NULL, "MemRegion array NULL"); 672 assert(count != 0, "No MemRegions provided"); 673 MutexLockerEx x(Heap_lock); 674 675 MemRegion reserved = _hrm.reserved(); 676 HeapWord* prev_last_addr = NULL; 677 HeapRegion* prev_last_region = NULL; 678 679 // Temporarily disable pretouching of heap pages. This interface is used 680 // when mmap'ing archived heap data in, so pre-touching is wasted. 681 FlagSetting fs(AlwaysPreTouch, false); 682 683 // Enable archive object checking used by G1MarkSweep. We have to let it know 684 // about each archive range, so that objects in those ranges aren't marked. 685 G1ArchiveAllocator::enable_archive_object_check(); 686 687 // For each specified MemRegion range, allocate the corresponding G1 688 // regions and mark them as archive regions. We expect the ranges 689 // in ascending starting address order, without overlap. 690 for (size_t i = 0; i < count; i++) { 691 MemRegion curr_range = ranges[i]; 692 HeapWord* start_address = curr_range.start(); 693 size_t word_size = curr_range.word_size(); 694 HeapWord* last_address = curr_range.last(); 695 size_t commits = 0; 696 697 guarantee(reserved.contains(start_address) && reserved.contains(last_address), 698 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 699 p2i(start_address), p2i(last_address)); 700 guarantee(start_address > prev_last_addr, 701 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 702 p2i(start_address), p2i(prev_last_addr)); 703 prev_last_addr = last_address; 704 705 // Check for ranges that start in the same G1 region in which the previous 706 // range ended, and adjust the start address so we don't try to allocate 707 // the same region again. If the current range is entirely within that 708 // region, skip it, just adjusting the recorded top. 709 HeapRegion* start_region = _hrm.addr_to_region(start_address); 710 if ((prev_last_region != NULL) && (start_region == prev_last_region)) { 711 start_address = start_region->end(); 712 if (start_address > last_address) { 713 increase_used(word_size * HeapWordSize); 714 start_region->set_top(last_address + 1); 715 continue; 716 } 717 start_region->set_top(start_address); 718 curr_range = MemRegion(start_address, last_address + 1); 719 start_region = _hrm.addr_to_region(start_address); 720 } 721 722 // Perform the actual region allocation, exiting if it fails. 723 // Then note how much new space we have allocated. 724 if (!_hrm.allocate_containing_regions(curr_range, &commits, workers())) { 725 return false; 726 } 727 increase_used(word_size * HeapWordSize); 728 if (commits != 0) { 729 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B", 730 HeapRegion::GrainWords * HeapWordSize * commits); 731 732 } 733 734 // Mark each G1 region touched by the range as archive, add it to 735 // the old set, and set the allocation context and top. 736 HeapRegion* curr_region = _hrm.addr_to_region(start_address); 737 HeapRegion* last_region = _hrm.addr_to_region(last_address); 738 prev_last_region = last_region; 739 740 while (curr_region != NULL) { 741 assert(curr_region->is_empty() && !curr_region->is_pinned(), 742 "Region already in use (index %u)", curr_region->hrm_index()); 743 curr_region->set_allocation_context(AllocationContext::system()); 744 if (open) { 745 curr_region->set_open_archive(); 746 } else { 747 curr_region->set_closed_archive(); 748 } 749 _hr_printer.alloc(curr_region); 750 _old_set.add(curr_region); 751 HeapWord* top; 752 HeapRegion* next_region; 753 if (curr_region != last_region) { 754 top = curr_region->end(); 755 next_region = _hrm.next_region_in_heap(curr_region); 756 } else { 757 top = last_address + 1; 758 next_region = NULL; 759 } 760 curr_region->set_top(top); 761 curr_region->set_first_dead(top); 762 curr_region->set_end_of_live(top); 763 curr_region = next_region; 764 } 765 766 // Notify mark-sweep of the archive 767 G1ArchiveAllocator::set_range_archive(curr_range, open); 768 } 769 return true; 770 } 771 772 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) { 773 assert(!is_init_completed(), "Expect to be called at JVM init time"); 774 assert(ranges != NULL, "MemRegion array NULL"); 775 assert(count != 0, "No MemRegions provided"); 776 MemRegion reserved = _hrm.reserved(); 777 HeapWord *prev_last_addr = NULL; 778 HeapRegion* prev_last_region = NULL; 779 780 // For each MemRegion, create filler objects, if needed, in the G1 regions 781 // that contain the address range. The address range actually within the 782 // MemRegion will not be modified. That is assumed to have been initialized 783 // elsewhere, probably via an mmap of archived heap data. 784 MutexLockerEx x(Heap_lock); 785 for (size_t i = 0; i < count; i++) { 786 HeapWord* start_address = ranges[i].start(); 787 HeapWord* last_address = ranges[i].last(); 788 789 assert(reserved.contains(start_address) && reserved.contains(last_address), 790 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 791 p2i(start_address), p2i(last_address)); 792 assert(start_address > prev_last_addr, 793 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 794 p2i(start_address), p2i(prev_last_addr)); 795 796 HeapRegion* start_region = _hrm.addr_to_region(start_address); 797 HeapRegion* last_region = _hrm.addr_to_region(last_address); 798 HeapWord* bottom_address = start_region->bottom(); 799 800 // Check for a range beginning in the same region in which the 801 // previous one ended. 802 if (start_region == prev_last_region) { 803 bottom_address = prev_last_addr + 1; 804 } 805 806 // Verify that the regions were all marked as archive regions by 807 // alloc_archive_regions. 808 HeapRegion* curr_region = start_region; 809 while (curr_region != NULL) { 810 guarantee(curr_region->is_archive(), 811 "Expected archive region at index %u", curr_region->hrm_index()); 812 if (curr_region != last_region) { 813 curr_region = _hrm.next_region_in_heap(curr_region); 814 } else { 815 curr_region = NULL; 816 } 817 } 818 819 prev_last_addr = last_address; 820 prev_last_region = last_region; 821 822 // Fill the memory below the allocated range with dummy object(s), 823 // if the region bottom does not match the range start, or if the previous 824 // range ended within the same G1 region, and there is a gap. 825 if (start_address != bottom_address) { 826 size_t fill_size = pointer_delta(start_address, bottom_address); 827 G1CollectedHeap::fill_with_objects(bottom_address, fill_size); 828 increase_used(fill_size * HeapWordSize); 829 } 830 } 831 } 832 833 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size, 834 uint* gc_count_before_ret, 835 uint* gclocker_retry_count_ret) { 836 assert_heap_not_locked_and_not_at_safepoint(); 837 assert(!is_humongous(word_size), "attempt_allocation() should not " 838 "be called for humongous allocation requests"); 839 840 AllocationContext_t context = AllocationContext::current(); 841 HeapWord* result = _allocator->attempt_allocation(word_size, context); 842 843 if (result == NULL) { 844 result = attempt_allocation_slow(word_size, 845 context, 846 gc_count_before_ret, 847 gclocker_retry_count_ret); 848 } 849 assert_heap_not_locked(); 850 if (result != NULL) { 851 dirty_young_block(result, word_size); 852 } 853 return result; 854 } 855 856 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) { 857 assert(!is_init_completed(), "Expect to be called at JVM init time"); 858 assert(ranges != NULL, "MemRegion array NULL"); 859 assert(count != 0, "No MemRegions provided"); 860 MemRegion reserved = _hrm.reserved(); 861 HeapWord* prev_last_addr = NULL; 862 HeapRegion* prev_last_region = NULL; 863 size_t size_used = 0; 864 size_t uncommitted_regions = 0; 865 866 // For each Memregion, free the G1 regions that constitute it, and 867 // notify mark-sweep that the range is no longer to be considered 'archive.' 868 MutexLockerEx x(Heap_lock); 869 for (size_t i = 0; i < count; i++) { 870 HeapWord* start_address = ranges[i].start(); 871 HeapWord* last_address = ranges[i].last(); 872 873 assert(reserved.contains(start_address) && reserved.contains(last_address), 874 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 875 p2i(start_address), p2i(last_address)); 876 assert(start_address > prev_last_addr, 877 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 878 p2i(start_address), p2i(prev_last_addr)); 879 size_used += ranges[i].byte_size(); 880 prev_last_addr = last_address; 881 882 HeapRegion* start_region = _hrm.addr_to_region(start_address); 883 HeapRegion* last_region = _hrm.addr_to_region(last_address); 884 885 // Check for ranges that start in the same G1 region in which the previous 886 // range ended, and adjust the start address so we don't try to free 887 // the same region again. If the current range is entirely within that 888 // region, skip it. 889 if (start_region == prev_last_region) { 890 start_address = start_region->end(); 891 if (start_address > last_address) { 892 continue; 893 } 894 start_region = _hrm.addr_to_region(start_address); 895 } 896 prev_last_region = last_region; 897 898 // After verifying that each region was marked as an archive region by 899 // alloc_archive_regions, set it free and empty and uncommit it. 900 HeapRegion* curr_region = start_region; 901 while (curr_region != NULL) { 902 guarantee(curr_region->is_archive(), 903 "Expected archive region at index %u", curr_region->hrm_index()); 904 uint curr_index = curr_region->hrm_index(); 905 _old_set.remove(curr_region); 906 curr_region->set_free(); 907 curr_region->set_top(curr_region->bottom()); 908 if (curr_region != last_region) { 909 curr_region = _hrm.next_region_in_heap(curr_region); 910 } else { 911 curr_region = NULL; 912 } 913 _hrm.shrink_at(curr_index, 1); 914 uncommitted_regions++; 915 } 916 917 // Notify mark-sweep that this is no longer an archive range. 918 G1ArchiveAllocator::set_range_archive(ranges[i], false); 919 } 920 921 if (uncommitted_regions != 0) { 922 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B", 923 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions); 924 } 925 decrease_used(size_used); 926 } 927 928 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size, 929 uint* gc_count_before_ret, 930 uint* gclocker_retry_count_ret) { 931 // The structure of this method has a lot of similarities to 932 // attempt_allocation_slow(). The reason these two were not merged 933 // into a single one is that such a method would require several "if 934 // allocation is not humongous do this, otherwise do that" 935 // conditional paths which would obscure its flow. In fact, an early 936 // version of this code did use a unified method which was harder to 937 // follow and, as a result, it had subtle bugs that were hard to 938 // track down. So keeping these two methods separate allows each to 939 // be more readable. It will be good to keep these two in sync as 940 // much as possible. 941 942 assert_heap_not_locked_and_not_at_safepoint(); 943 assert(is_humongous(word_size), "attempt_allocation_humongous() " 944 "should only be called for humongous allocations"); 945 946 // Humongous objects can exhaust the heap quickly, so we should check if we 947 // need to start a marking cycle at each humongous object allocation. We do 948 // the check before we do the actual allocation. The reason for doing it 949 // before the allocation is that we avoid having to keep track of the newly 950 // allocated memory while we do a GC. 951 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation", 952 word_size)) { 953 collect(GCCause::_g1_humongous_allocation); 954 } 955 956 // We will loop until a) we manage to successfully perform the 957 // allocation or b) we successfully schedule a collection which 958 // fails to perform the allocation. b) is the only case when we'll 959 // return NULL. 960 HeapWord* result = NULL; 961 for (int try_count = 1; /* we'll return */; try_count += 1) { 962 bool should_try_gc; 963 uint gc_count_before; 964 965 { 966 MutexLockerEx x(Heap_lock); 967 968 // Given that humongous objects are not allocated in young 969 // regions, we'll first try to do the allocation without doing a 970 // collection hoping that there's enough space in the heap. 971 result = humongous_obj_allocate(word_size, AllocationContext::current()); 972 if (result != NULL) { 973 size_t size_in_regions = humongous_obj_size_in_regions(word_size); 974 g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes); 975 return result; 976 } 977 978 if (GCLocker::is_active_and_needs_gc()) { 979 should_try_gc = false; 980 } else { 981 // The GCLocker may not be active but the GCLocker initiated 982 // GC may not yet have been performed (GCLocker::needs_gc() 983 // returns true). In this case we do not try this GC and 984 // wait until the GCLocker initiated GC is performed, and 985 // then retry the allocation. 986 if (GCLocker::needs_gc()) { 987 should_try_gc = false; 988 } else { 989 // Read the GC count while still holding the Heap_lock. 990 gc_count_before = total_collections(); 991 should_try_gc = true; 992 } 993 } 994 } 995 996 if (should_try_gc) { 997 // If we failed to allocate the humongous object, we should try to 998 // do a collection pause (if we're allowed) in case it reclaims 999 // enough space for the allocation to succeed after the pause. 1000 1001 bool succeeded; 1002 result = do_collection_pause(word_size, gc_count_before, &succeeded, 1003 GCCause::_g1_humongous_allocation); 1004 if (result != NULL) { 1005 assert(succeeded, "only way to get back a non-NULL result"); 1006 return result; 1007 } 1008 1009 if (succeeded) { 1010 // If we get here we successfully scheduled a collection which 1011 // failed to allocate. No point in trying to allocate 1012 // further. We'll just return NULL. 1013 MutexLockerEx x(Heap_lock); 1014 *gc_count_before_ret = total_collections(); 1015 return NULL; 1016 } 1017 } else { 1018 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { 1019 MutexLockerEx x(Heap_lock); 1020 *gc_count_before_ret = total_collections(); 1021 return NULL; 1022 } 1023 // The GCLocker is either active or the GCLocker initiated 1024 // GC has not yet been performed. Stall until it is and 1025 // then retry the allocation. 1026 GCLocker::stall_until_clear(); 1027 (*gclocker_retry_count_ret) += 1; 1028 } 1029 1030 // We can reach here if we were unsuccessful in scheduling a 1031 // collection (because another thread beat us to it) or if we were 1032 // stalled due to the GC locker. In either can we should retry the 1033 // allocation attempt in case another thread successfully 1034 // performed a collection and reclaimed enough space. Give a 1035 // warning if we seem to be looping forever. 1036 1037 if ((QueuedAllocationWarningCount > 0) && 1038 (try_count % QueuedAllocationWarningCount == 0)) { 1039 log_warning(gc)("G1CollectedHeap::attempt_allocation_humongous() " 1040 "retries %d times", try_count); 1041 } 1042 } 1043 1044 ShouldNotReachHere(); 1045 return NULL; 1046 } 1047 1048 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size, 1049 AllocationContext_t context, 1050 bool expect_null_mutator_alloc_region) { 1051 assert_at_safepoint(true /* should_be_vm_thread */); 1052 assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region, 1053 "the current alloc region was unexpectedly found to be non-NULL"); 1054 1055 if (!is_humongous(word_size)) { 1056 return _allocator->attempt_allocation_locked(word_size, context); 1057 } else { 1058 HeapWord* result = humongous_obj_allocate(word_size, context); 1059 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) { 1060 collector_state()->set_initiate_conc_mark_if_possible(true); 1061 } 1062 return result; 1063 } 1064 1065 ShouldNotReachHere(); 1066 } 1067 1068 class PostCompactionPrinterClosure: public HeapRegionClosure { 1069 private: 1070 G1HRPrinter* _hr_printer; 1071 public: 1072 bool doHeapRegion(HeapRegion* hr) { 1073 assert(!hr->is_young(), "not expecting to find young regions"); 1074 _hr_printer->post_compaction(hr); 1075 return false; 1076 } 1077 1078 PostCompactionPrinterClosure(G1HRPrinter* hr_printer) 1079 : _hr_printer(hr_printer) { } 1080 }; 1081 1082 void G1CollectedHeap::print_hrm_post_compaction() { 1083 if (_hr_printer.is_active()) { 1084 PostCompactionPrinterClosure cl(hr_printer()); 1085 heap_region_iterate(&cl); 1086 } 1087 } 1088 1089 void G1CollectedHeap::abort_concurrent_cycle() { 1090 // Note: When we have a more flexible GC logging framework that 1091 // allows us to add optional attributes to a GC log record we 1092 // could consider timing and reporting how long we wait in the 1093 // following two methods. 1094 wait_while_free_regions_coming(); 1095 // If we start the compaction before the CM threads finish 1096 // scanning the root regions we might trip them over as we'll 1097 // be moving objects / updating references. So let's wait until 1098 // they are done. By telling them to abort, they should complete 1099 // early. 1100 _cm->root_regions()->abort(); 1101 _cm->root_regions()->wait_until_scan_finished(); 1102 append_secondary_free_list_if_not_empty_with_lock(); 1103 1104 // Disable discovery and empty the discovered lists 1105 // for the CM ref processor. 1106 ref_processor_cm()->disable_discovery(); 1107 ref_processor_cm()->abandon_partial_discovery(); 1108 ref_processor_cm()->verify_no_references_recorded(); 1109 1110 // Abandon current iterations of concurrent marking and concurrent 1111 // refinement, if any are in progress. 1112 concurrent_mark()->abort(); 1113 } 1114 1115 void G1CollectedHeap::prepare_heap_for_full_collection() { 1116 // Make sure we'll choose a new allocation region afterwards. 1117 _allocator->release_mutator_alloc_region(); 1118 _allocator->abandon_gc_alloc_regions(); 1119 g1_rem_set()->cleanupHRRS(); 1120 1121 // We may have added regions to the current incremental collection 1122 // set between the last GC or pause and now. We need to clear the 1123 // incremental collection set and then start rebuilding it afresh 1124 // after this full GC. 1125 abandon_collection_set(collection_set()); 1126 1127 tear_down_region_sets(false /* free_list_only */); 1128 collector_state()->set_gcs_are_young(true); 1129 } 1130 1131 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) { 1132 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant"); 1133 assert(used() == recalculate_used(), "Should be equal"); 1134 _verifier->verify_region_sets_optional(); 1135 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull); 1136 _verifier->check_bitmaps("Full GC Start"); 1137 } 1138 1139 void G1CollectedHeap::prepare_heap_for_mutators() { 1140 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 1141 ClassLoaderDataGraph::purge(); 1142 MetaspaceAux::verify_metrics(); 1143 1144 // Prepare heap for normal collections. 1145 assert(num_free_regions() == 0, "we should not have added any free regions"); 1146 rebuild_region_sets(false /* free_list_only */); 1147 abort_refinement(); 1148 resize_if_necessary_after_full_collection(); 1149 1150 // Rebuild the strong code root lists for each region 1151 rebuild_strong_code_roots(); 1152 1153 // Start a new incremental collection set for the next pause 1154 start_new_collection_set(); 1155 1156 _allocator->init_mutator_alloc_region(); 1157 1158 // Post collection state updates. 1159 MetaspaceGC::compute_new_size(); 1160 } 1161 1162 void G1CollectedHeap::abort_refinement() { 1163 if (_hot_card_cache->use_cache()) { 1164 _hot_card_cache->reset_hot_cache(); 1165 } 1166 1167 // Discard all remembered set updates. 1168 JavaThread::dirty_card_queue_set().abandon_logs(); 1169 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty"); 1170 } 1171 1172 void G1CollectedHeap::verify_after_full_collection() { 1173 check_gc_time_stamps(); 1174 _hrm.verify_optional(); 1175 _verifier->verify_region_sets_optional(); 1176 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull); 1177 // Clear the previous marking bitmap, if needed for bitmap verification. 1178 // Note we cannot do this when we clear the next marking bitmap in 1179 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the 1180 // objects marked during a full GC against the previous bitmap. 1181 // But we need to clear it before calling check_bitmaps below since 1182 // the full GC has compacted objects and updated TAMS but not updated 1183 // the prev bitmap. 1184 if (G1VerifyBitmaps) { 1185 GCTraceTime(Debug, gc)("Clear Bitmap for Verification"); 1186 _cm->clear_prev_bitmap(workers()); 1187 } 1188 _verifier->check_bitmaps("Full GC End"); 1189 1190 // At this point there should be no regions in the 1191 // entire heap tagged as young. 1192 assert(check_young_list_empty(), "young list should be empty at this point"); 1193 1194 // Note: since we've just done a full GC, concurrent 1195 // marking is no longer active. Therefore we need not 1196 // re-enable reference discovery for the CM ref processor. 1197 // That will be done at the start of the next marking cycle. 1198 // We also know that the STW processor should no longer 1199 // discover any new references. 1200 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 1201 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition"); 1202 ref_processor_stw()->verify_no_references_recorded(); 1203 ref_processor_cm()->verify_no_references_recorded(); 1204 } 1205 1206 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) { 1207 // Post collection logging. 1208 // We should do this after we potentially resize the heap so 1209 // that all the COMMIT / UNCOMMIT events are generated before 1210 // the compaction events. 1211 print_hrm_post_compaction(); 1212 heap_transition->print(); 1213 print_heap_after_gc(); 1214 print_heap_regions(); 1215 #ifdef TRACESPINNING 1216 ParallelTaskTerminator::print_termination_counts(); 1217 #endif 1218 } 1219 1220 bool G1CollectedHeap::do_full_collection(bool explicit_gc, 1221 bool clear_all_soft_refs) { 1222 assert_at_safepoint(true /* should_be_vm_thread */); 1223 1224 if (GCLocker::check_active_before_gc()) { 1225 // Full GC was not completed. 1226 return false; 1227 } 1228 1229 const bool do_clear_all_soft_refs = clear_all_soft_refs || 1230 collector_policy()->should_clear_all_soft_refs(); 1231 1232 G1FullCollector collector(this, &_full_gc_memory_manager, explicit_gc, do_clear_all_soft_refs); 1233 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true); 1234 1235 collector.prepare_collection(); 1236 collector.collect(); 1237 collector.complete_collection(); 1238 1239 // Full collection was successfully completed. 1240 return true; 1241 } 1242 1243 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) { 1244 // Currently, there is no facility in the do_full_collection(bool) API to notify 1245 // the caller that the collection did not succeed (e.g., because it was locked 1246 // out by the GC locker). So, right now, we'll ignore the return value. 1247 bool dummy = do_full_collection(true, /* explicit_gc */ 1248 clear_all_soft_refs); 1249 } 1250 1251 void G1CollectedHeap::resize_if_necessary_after_full_collection() { 1252 // Capacity, free and used after the GC counted as full regions to 1253 // include the waste in the following calculations. 1254 const size_t capacity_after_gc = capacity(); 1255 const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes(); 1256 1257 // This is enforced in arguments.cpp. 1258 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, 1259 "otherwise the code below doesn't make sense"); 1260 1261 // We don't have floating point command-line arguments 1262 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0; 1263 const double maximum_used_percentage = 1.0 - minimum_free_percentage; 1264 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0; 1265 const double minimum_used_percentage = 1.0 - maximum_free_percentage; 1266 1267 const size_t min_heap_size = collector_policy()->min_heap_byte_size(); 1268 const size_t max_heap_size = collector_policy()->max_heap_byte_size(); 1269 1270 // We have to be careful here as these two calculations can overflow 1271 // 32-bit size_t's. 1272 double used_after_gc_d = (double) used_after_gc; 1273 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage; 1274 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage; 1275 1276 // Let's make sure that they are both under the max heap size, which 1277 // by default will make them fit into a size_t. 1278 double desired_capacity_upper_bound = (double) max_heap_size; 1279 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d, 1280 desired_capacity_upper_bound); 1281 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d, 1282 desired_capacity_upper_bound); 1283 1284 // We can now safely turn them into size_t's. 1285 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d; 1286 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d; 1287 1288 // This assert only makes sense here, before we adjust them 1289 // with respect to the min and max heap size. 1290 assert(minimum_desired_capacity <= maximum_desired_capacity, 1291 "minimum_desired_capacity = " SIZE_FORMAT ", " 1292 "maximum_desired_capacity = " SIZE_FORMAT, 1293 minimum_desired_capacity, maximum_desired_capacity); 1294 1295 // Should not be greater than the heap max size. No need to adjust 1296 // it with respect to the heap min size as it's a lower bound (i.e., 1297 // we'll try to make the capacity larger than it, not smaller). 1298 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size); 1299 // Should not be less than the heap min size. No need to adjust it 1300 // with respect to the heap max size as it's an upper bound (i.e., 1301 // we'll try to make the capacity smaller than it, not greater). 1302 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size); 1303 1304 if (capacity_after_gc < minimum_desired_capacity) { 1305 // Don't expand unless it's significant 1306 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc; 1307 1308 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). " 1309 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B " 1310 "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)", 1311 capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio); 1312 1313 expand(expand_bytes, _workers); 1314 1315 // No expansion, now see if we want to shrink 1316 } else if (capacity_after_gc > maximum_desired_capacity) { 1317 // Capacity too large, compute shrinking size 1318 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity; 1319 1320 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). " 1321 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B " 1322 "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)", 1323 capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio); 1324 1325 shrink(shrink_bytes); 1326 } 1327 } 1328 1329 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size, 1330 AllocationContext_t context, 1331 bool do_gc, 1332 bool clear_all_soft_refs, 1333 bool expect_null_mutator_alloc_region, 1334 bool* gc_succeeded) { 1335 *gc_succeeded = true; 1336 // Let's attempt the allocation first. 1337 HeapWord* result = 1338 attempt_allocation_at_safepoint(word_size, 1339 context, 1340 expect_null_mutator_alloc_region); 1341 if (result != NULL) { 1342 assert(*gc_succeeded, "sanity"); 1343 return result; 1344 } 1345 1346 // In a G1 heap, we're supposed to keep allocation from failing by 1347 // incremental pauses. Therefore, at least for now, we'll favor 1348 // expansion over collection. (This might change in the future if we can 1349 // do something smarter than full collection to satisfy a failed alloc.) 1350 result = expand_and_allocate(word_size, context); 1351 if (result != NULL) { 1352 assert(*gc_succeeded, "sanity"); 1353 return result; 1354 } 1355 1356 if (do_gc) { 1357 // Expansion didn't work, we'll try to do a Full GC. 1358 *gc_succeeded = do_full_collection(false, /* explicit_gc */ 1359 clear_all_soft_refs); 1360 } 1361 1362 return NULL; 1363 } 1364 1365 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size, 1366 AllocationContext_t context, 1367 bool* succeeded) { 1368 assert_at_safepoint(true /* should_be_vm_thread */); 1369 1370 // Attempts to allocate followed by Full GC. 1371 HeapWord* result = 1372 satisfy_failed_allocation_helper(word_size, 1373 context, 1374 true, /* do_gc */ 1375 false, /* clear_all_soft_refs */ 1376 false, /* expect_null_mutator_alloc_region */ 1377 succeeded); 1378 1379 if (result != NULL || !*succeeded) { 1380 return result; 1381 } 1382 1383 // Attempts to allocate followed by Full GC that will collect all soft references. 1384 result = satisfy_failed_allocation_helper(word_size, 1385 context, 1386 true, /* do_gc */ 1387 true, /* clear_all_soft_refs */ 1388 true, /* expect_null_mutator_alloc_region */ 1389 succeeded); 1390 1391 if (result != NULL || !*succeeded) { 1392 return result; 1393 } 1394 1395 // Attempts to allocate, no GC 1396 result = satisfy_failed_allocation_helper(word_size, 1397 context, 1398 false, /* do_gc */ 1399 false, /* clear_all_soft_refs */ 1400 true, /* expect_null_mutator_alloc_region */ 1401 succeeded); 1402 1403 if (result != NULL) { 1404 assert(*succeeded, "sanity"); 1405 return result; 1406 } 1407 1408 assert(!collector_policy()->should_clear_all_soft_refs(), 1409 "Flag should have been handled and cleared prior to this point"); 1410 1411 // What else? We might try synchronous finalization later. If the total 1412 // space available is large enough for the allocation, then a more 1413 // complete compaction phase than we've tried so far might be 1414 // appropriate. 1415 assert(*succeeded, "sanity"); 1416 return NULL; 1417 } 1418 1419 // Attempting to expand the heap sufficiently 1420 // to support an allocation of the given "word_size". If 1421 // successful, perform the allocation and return the address of the 1422 // allocated block, or else "NULL". 1423 1424 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) { 1425 assert_at_safepoint(true /* should_be_vm_thread */); 1426 1427 _verifier->verify_region_sets_optional(); 1428 1429 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes); 1430 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B", 1431 word_size * HeapWordSize); 1432 1433 1434 if (expand(expand_bytes, _workers)) { 1435 _hrm.verify_optional(); 1436 _verifier->verify_region_sets_optional(); 1437 return attempt_allocation_at_safepoint(word_size, 1438 context, 1439 false /* expect_null_mutator_alloc_region */); 1440 } 1441 return NULL; 1442 } 1443 1444 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) { 1445 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); 1446 aligned_expand_bytes = align_up(aligned_expand_bytes, 1447 HeapRegion::GrainBytes); 1448 1449 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B", 1450 expand_bytes, aligned_expand_bytes); 1451 1452 if (is_maximal_no_gc()) { 1453 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)"); 1454 return false; 1455 } 1456 1457 double expand_heap_start_time_sec = os::elapsedTime(); 1458 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes); 1459 assert(regions_to_expand > 0, "Must expand by at least one region"); 1460 1461 uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers); 1462 if (expand_time_ms != NULL) { 1463 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS; 1464 } 1465 1466 if (expanded_by > 0) { 1467 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes; 1468 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition"); 1469 g1_policy()->record_new_heap_size(num_regions()); 1470 } else { 1471 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)"); 1472 1473 // The expansion of the virtual storage space was unsuccessful. 1474 // Let's see if it was because we ran out of swap. 1475 if (G1ExitOnExpansionFailure && 1476 _hrm.available() >= regions_to_expand) { 1477 // We had head room... 1478 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion"); 1479 } 1480 } 1481 return regions_to_expand > 0; 1482 } 1483 1484 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) { 1485 size_t aligned_shrink_bytes = 1486 ReservedSpace::page_align_size_down(shrink_bytes); 1487 aligned_shrink_bytes = align_down(aligned_shrink_bytes, 1488 HeapRegion::GrainBytes); 1489 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes); 1490 1491 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove); 1492 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes; 1493 1494 1495 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", 1496 shrink_bytes, aligned_shrink_bytes, shrunk_bytes); 1497 if (num_regions_removed > 0) { 1498 g1_policy()->record_new_heap_size(num_regions()); 1499 } else { 1500 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)"); 1501 } 1502 } 1503 1504 void G1CollectedHeap::shrink(size_t shrink_bytes) { 1505 _verifier->verify_region_sets_optional(); 1506 1507 // We should only reach here at the end of a Full GC which means we 1508 // should not not be holding to any GC alloc regions. The method 1509 // below will make sure of that and do any remaining clean up. 1510 _allocator->abandon_gc_alloc_regions(); 1511 1512 // Instead of tearing down / rebuilding the free lists here, we 1513 // could instead use the remove_all_pending() method on free_list to 1514 // remove only the ones that we need to remove. 1515 tear_down_region_sets(true /* free_list_only */); 1516 shrink_helper(shrink_bytes); 1517 rebuild_region_sets(true /* free_list_only */); 1518 1519 _hrm.verify_optional(); 1520 _verifier->verify_region_sets_optional(); 1521 } 1522 1523 // Public methods. 1524 1525 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) : 1526 CollectedHeap(), 1527 _young_gen_sampling_thread(NULL), 1528 _collector_policy(collector_policy), 1529 _memory_manager("G1 Young Generation", "end of minor GC"), 1530 _full_gc_memory_manager("G1 Old Generation", "end of major GC"), 1531 _eden_pool(NULL), 1532 _survivor_pool(NULL), 1533 _old_pool(NULL), 1534 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()), 1535 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()), 1536 _g1_policy(create_g1_policy(_gc_timer_stw)), 1537 _collection_set(this, _g1_policy), 1538 _dirty_card_queue_set(false), 1539 _is_alive_closure_cm(this), 1540 _is_alive_closure_stw(this), 1541 _ref_processor_cm(NULL), 1542 _ref_processor_stw(NULL), 1543 _bot(NULL), 1544 _hot_card_cache(NULL), 1545 _g1_rem_set(NULL), 1546 _cr(NULL), 1547 _g1mm(NULL), 1548 _preserved_marks_set(true /* in_c_heap */), 1549 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()), 1550 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()), 1551 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()), 1552 _humongous_reclaim_candidates(), 1553 _has_humongous_reclaim_candidates(false), 1554 _archive_allocator(NULL), 1555 _free_regions_coming(false), 1556 _gc_time_stamp(0), 1557 _summary_bytes_used(0), 1558 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight), 1559 _old_evac_stats("Old", OldPLABSize, PLABWeight), 1560 _expand_heap_after_alloc_failure(true), 1561 _old_marking_cycles_started(0), 1562 _old_marking_cycles_completed(0), 1563 _in_cset_fast_test() { 1564 1565 _workers = new WorkGang("GC Thread", ParallelGCThreads, 1566 /* are_GC_task_threads */true, 1567 /* are_ConcurrentGC_threads */false); 1568 _workers->initialize_workers(); 1569 _verifier = new G1HeapVerifier(this); 1570 1571 _allocator = G1Allocator::create_allocator(this); 1572 1573 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics()); 1574 1575 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords); 1576 1577 // Override the default _filler_array_max_size so that no humongous filler 1578 // objects are created. 1579 _filler_array_max_size = _humongous_object_threshold_in_words; 1580 1581 uint n_queues = ParallelGCThreads; 1582 _task_queues = new RefToScanQueueSet(n_queues); 1583 1584 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC); 1585 1586 for (uint i = 0; i < n_queues; i++) { 1587 RefToScanQueue* q = new RefToScanQueue(); 1588 q->initialize(); 1589 _task_queues->register_queue(i, q); 1590 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo(); 1591 } 1592 1593 // Initialize the G1EvacuationFailureALot counters and flags. 1594 NOT_PRODUCT(reset_evacuation_should_fail();) 1595 1596 guarantee(_task_queues != NULL, "task_queues allocation failure."); 1597 } 1598 1599 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description, 1600 size_t size, 1601 size_t translation_factor) { 1602 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1); 1603 // Allocate a new reserved space, preferring to use large pages. 1604 ReservedSpace rs(size, preferred_page_size); 1605 G1RegionToSpaceMapper* result = 1606 G1RegionToSpaceMapper::create_mapper(rs, 1607 size, 1608 rs.alignment(), 1609 HeapRegion::GrainBytes, 1610 translation_factor, 1611 mtGC); 1612 1613 os::trace_page_sizes_for_requested_size(description, 1614 size, 1615 preferred_page_size, 1616 rs.alignment(), 1617 rs.base(), 1618 rs.size()); 1619 1620 return result; 1621 } 1622 1623 jint G1CollectedHeap::initialize_concurrent_refinement() { 1624 jint ecode = JNI_OK; 1625 _cr = G1ConcurrentRefine::create(&ecode); 1626 return ecode; 1627 } 1628 1629 jint G1CollectedHeap::initialize_young_gen_sampling_thread() { 1630 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread(); 1631 if (_young_gen_sampling_thread->osthread() == NULL) { 1632 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread"); 1633 return JNI_ENOMEM; 1634 } 1635 return JNI_OK; 1636 } 1637 1638 jint G1CollectedHeap::initialize() { 1639 CollectedHeap::pre_initialize(); 1640 os::enable_vtime(); 1641 1642 // Necessary to satisfy locking discipline assertions. 1643 1644 MutexLocker x(Heap_lock); 1645 1646 // While there are no constraints in the GC code that HeapWordSize 1647 // be any particular value, there are multiple other areas in the 1648 // system which believe this to be true (e.g. oop->object_size in some 1649 // cases incorrectly returns the size in wordSize units rather than 1650 // HeapWordSize). 1651 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 1652 1653 size_t init_byte_size = collector_policy()->initial_heap_byte_size(); 1654 size_t max_byte_size = collector_policy()->max_heap_byte_size(); 1655 size_t heap_alignment = collector_policy()->heap_alignment(); 1656 1657 // Ensure that the sizes are properly aligned. 1658 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1659 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1660 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap"); 1661 1662 // Reserve the maximum. 1663 1664 // When compressed oops are enabled, the preferred heap base 1665 // is calculated by subtracting the requested size from the 1666 // 32Gb boundary and using the result as the base address for 1667 // heap reservation. If the requested size is not aligned to 1668 // HeapRegion::GrainBytes (i.e. the alignment that is passed 1669 // into the ReservedHeapSpace constructor) then the actual 1670 // base of the reserved heap may end up differing from the 1671 // address that was requested (i.e. the preferred heap base). 1672 // If this happens then we could end up using a non-optimal 1673 // compressed oops mode. 1674 1675 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size, 1676 heap_alignment); 1677 1678 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size())); 1679 1680 // Create the barrier set for the entire reserved region. 1681 G1SATBCardTableLoggingModRefBS* bs 1682 = new G1SATBCardTableLoggingModRefBS(reserved_region()); 1683 bs->initialize(); 1684 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity"); 1685 set_barrier_set(bs); 1686 1687 // Create the hot card cache. 1688 _hot_card_cache = new G1HotCardCache(this); 1689 1690 // Carve out the G1 part of the heap. 1691 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size); 1692 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size(); 1693 G1RegionToSpaceMapper* heap_storage = 1694 G1RegionToSpaceMapper::create_mapper(g1_rs, 1695 g1_rs.size(), 1696 page_size, 1697 HeapRegion::GrainBytes, 1698 1, 1699 mtJavaHeap); 1700 os::trace_page_sizes("Heap", 1701 collector_policy()->min_heap_byte_size(), 1702 max_byte_size, 1703 page_size, 1704 heap_rs.base(), 1705 heap_rs.size()); 1706 heap_storage->set_mapping_changed_listener(&_listener); 1707 1708 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps. 1709 G1RegionToSpaceMapper* bot_storage = 1710 create_aux_memory_mapper("Block Offset Table", 1711 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize), 1712 G1BlockOffsetTable::heap_map_factor()); 1713 1714 G1RegionToSpaceMapper* cardtable_storage = 1715 create_aux_memory_mapper("Card Table", 1716 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize), 1717 G1SATBCardTableLoggingModRefBS::heap_map_factor()); 1718 1719 G1RegionToSpaceMapper* card_counts_storage = 1720 create_aux_memory_mapper("Card Counts Table", 1721 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize), 1722 G1CardCounts::heap_map_factor()); 1723 1724 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size()); 1725 G1RegionToSpaceMapper* prev_bitmap_storage = 1726 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1727 G1RegionToSpaceMapper* next_bitmap_storage = 1728 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1729 1730 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage); 1731 g1_barrier_set()->initialize(cardtable_storage); 1732 // Do later initialization work for concurrent refinement. 1733 _hot_card_cache->initialize(card_counts_storage); 1734 1735 // 6843694 - ensure that the maximum region index can fit 1736 // in the remembered set structures. 1737 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; 1738 guarantee((max_regions() - 1) <= max_region_idx, "too many regions"); 1739 1740 // Also create a G1 rem set. 1741 _g1_rem_set = new G1RemSet(this, g1_barrier_set(), _hot_card_cache); 1742 _g1_rem_set->initialize(max_capacity(), max_regions()); 1743 1744 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; 1745 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); 1746 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region, 1747 "too many cards per region"); 1748 1749 FreeRegionList::set_unrealistically_long_length(max_regions() + 1); 1750 1751 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage); 1752 1753 { 1754 HeapWord* start = _hrm.reserved().start(); 1755 HeapWord* end = _hrm.reserved().end(); 1756 size_t granularity = HeapRegion::GrainBytes; 1757 1758 _in_cset_fast_test.initialize(start, end, granularity); 1759 _humongous_reclaim_candidates.initialize(start, end, granularity); 1760 } 1761 1762 // Create the G1ConcurrentMark data structure and thread. 1763 // (Must do this late, so that "max_regions" is defined.) 1764 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage); 1765 if (_cm == NULL || !_cm->completed_initialization()) { 1766 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark"); 1767 return JNI_ENOMEM; 1768 } 1769 _cmThread = _cm->cm_thread(); 1770 1771 // Now expand into the initial heap size. 1772 if (!expand(init_byte_size, _workers)) { 1773 vm_shutdown_during_initialization("Failed to allocate initial heap."); 1774 return JNI_ENOMEM; 1775 } 1776 1777 // Perform any initialization actions delegated to the policy. 1778 g1_policy()->init(this, &_collection_set); 1779 1780 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon, 1781 SATB_Q_FL_lock, 1782 G1SATBProcessCompletedThreshold, 1783 Shared_SATB_Q_lock); 1784 1785 jint ecode = initialize_concurrent_refinement(); 1786 if (ecode != JNI_OK) { 1787 return ecode; 1788 } 1789 1790 ecode = initialize_young_gen_sampling_thread(); 1791 if (ecode != JNI_OK) { 1792 return ecode; 1793 } 1794 1795 JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon, 1796 DirtyCardQ_FL_lock, 1797 (int)concurrent_refine()->yellow_zone(), 1798 (int)concurrent_refine()->red_zone(), 1799 Shared_DirtyCardQ_lock, 1800 NULL, // fl_owner 1801 true); // init_free_ids 1802 1803 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon, 1804 DirtyCardQ_FL_lock, 1805 -1, // never trigger processing 1806 -1, // no limit on length 1807 Shared_DirtyCardQ_lock, 1808 &JavaThread::dirty_card_queue_set()); 1809 1810 // Here we allocate the dummy HeapRegion that is required by the 1811 // G1AllocRegion class. 1812 HeapRegion* dummy_region = _hrm.get_dummy_region(); 1813 1814 // We'll re-use the same region whether the alloc region will 1815 // require BOT updates or not and, if it doesn't, then a non-young 1816 // region will complain that it cannot support allocations without 1817 // BOT updates. So we'll tag the dummy region as eden to avoid that. 1818 dummy_region->set_eden(); 1819 // Make sure it's full. 1820 dummy_region->set_top(dummy_region->end()); 1821 G1AllocRegion::setup(this, dummy_region); 1822 1823 _allocator->init_mutator_alloc_region(); 1824 1825 // Do create of the monitoring and management support so that 1826 // values in the heap have been properly initialized. 1827 _g1mm = new G1MonitoringSupport(this); 1828 1829 G1StringDedup::initialize(); 1830 1831 _preserved_marks_set.init(ParallelGCThreads); 1832 1833 _collection_set.initialize(max_regions()); 1834 1835 return JNI_OK; 1836 } 1837 1838 void G1CollectedHeap::initialize_serviceability() { 1839 _eden_pool = new G1EdenPool(this); 1840 _survivor_pool = new G1SurvivorPool(this); 1841 _old_pool = new G1OldGenPool(this); 1842 1843 _full_gc_memory_manager.add_pool(_eden_pool); 1844 _full_gc_memory_manager.add_pool(_survivor_pool); 1845 _full_gc_memory_manager.add_pool(_old_pool); 1846 1847 _memory_manager.add_pool(_eden_pool); 1848 _memory_manager.add_pool(_survivor_pool); 1849 1850 } 1851 1852 void G1CollectedHeap::stop() { 1853 // Stop all concurrent threads. We do this to make sure these threads 1854 // do not continue to execute and access resources (e.g. logging) 1855 // that are destroyed during shutdown. 1856 _cr->stop(); 1857 _young_gen_sampling_thread->stop(); 1858 _cmThread->stop(); 1859 if (G1StringDedup::is_enabled()) { 1860 G1StringDedup::stop(); 1861 } 1862 } 1863 1864 void G1CollectedHeap::safepoint_synchronize_begin() { 1865 SuspendibleThreadSet::synchronize(); 1866 } 1867 1868 void G1CollectedHeap::safepoint_synchronize_end() { 1869 SuspendibleThreadSet::desynchronize(); 1870 } 1871 1872 size_t G1CollectedHeap::conservative_max_heap_alignment() { 1873 return HeapRegion::max_region_size(); 1874 } 1875 1876 void G1CollectedHeap::post_initialize() { 1877 CollectedHeap::post_initialize(); 1878 ref_processing_init(); 1879 } 1880 1881 void G1CollectedHeap::ref_processing_init() { 1882 // Reference processing in G1 currently works as follows: 1883 // 1884 // * There are two reference processor instances. One is 1885 // used to record and process discovered references 1886 // during concurrent marking; the other is used to 1887 // record and process references during STW pauses 1888 // (both full and incremental). 1889 // * Both ref processors need to 'span' the entire heap as 1890 // the regions in the collection set may be dotted around. 1891 // 1892 // * For the concurrent marking ref processor: 1893 // * Reference discovery is enabled at initial marking. 1894 // * Reference discovery is disabled and the discovered 1895 // references processed etc during remarking. 1896 // * Reference discovery is MT (see below). 1897 // * Reference discovery requires a barrier (see below). 1898 // * Reference processing may or may not be MT 1899 // (depending on the value of ParallelRefProcEnabled 1900 // and ParallelGCThreads). 1901 // * A full GC disables reference discovery by the CM 1902 // ref processor and abandons any entries on it's 1903 // discovered lists. 1904 // 1905 // * For the STW processor: 1906 // * Non MT discovery is enabled at the start of a full GC. 1907 // * Processing and enqueueing during a full GC is non-MT. 1908 // * During a full GC, references are processed after marking. 1909 // 1910 // * Discovery (may or may not be MT) is enabled at the start 1911 // of an incremental evacuation pause. 1912 // * References are processed near the end of a STW evacuation pause. 1913 // * For both types of GC: 1914 // * Discovery is atomic - i.e. not concurrent. 1915 // * Reference discovery will not need a barrier. 1916 1917 MemRegion mr = reserved_region(); 1918 1919 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1); 1920 1921 // Concurrent Mark ref processor 1922 _ref_processor_cm = 1923 new ReferenceProcessor(mr, // span 1924 mt_processing, 1925 // mt processing 1926 ParallelGCThreads, 1927 // degree of mt processing 1928 (ParallelGCThreads > 1) || (ConcGCThreads > 1), 1929 // mt discovery 1930 MAX2(ParallelGCThreads, ConcGCThreads), 1931 // degree of mt discovery 1932 false, 1933 // Reference discovery is not atomic 1934 &_is_alive_closure_cm); 1935 // is alive closure 1936 // (for efficiency/performance) 1937 1938 // STW ref processor 1939 _ref_processor_stw = 1940 new ReferenceProcessor(mr, // span 1941 mt_processing, 1942 // mt processing 1943 ParallelGCThreads, 1944 // degree of mt processing 1945 (ParallelGCThreads > 1), 1946 // mt discovery 1947 ParallelGCThreads, 1948 // degree of mt discovery 1949 true, 1950 // Reference discovery is atomic 1951 &_is_alive_closure_stw); 1952 // is alive closure 1953 // (for efficiency/performance) 1954 } 1955 1956 CollectorPolicy* G1CollectedHeap::collector_policy() const { 1957 return _collector_policy; 1958 } 1959 1960 size_t G1CollectedHeap::capacity() const { 1961 return _hrm.length() * HeapRegion::GrainBytes; 1962 } 1963 1964 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const { 1965 return _hrm.total_free_bytes(); 1966 } 1967 1968 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) { 1969 hr->reset_gc_time_stamp(); 1970 } 1971 1972 #ifndef PRODUCT 1973 1974 class CheckGCTimeStampsHRClosure : public HeapRegionClosure { 1975 private: 1976 unsigned _gc_time_stamp; 1977 bool _failures; 1978 1979 public: 1980 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) : 1981 _gc_time_stamp(gc_time_stamp), _failures(false) { } 1982 1983 virtual bool doHeapRegion(HeapRegion* hr) { 1984 unsigned region_gc_time_stamp = hr->get_gc_time_stamp(); 1985 if (_gc_time_stamp != region_gc_time_stamp) { 1986 log_error(gc, verify)("Region " HR_FORMAT " has GC time stamp = %d, expected %d", HR_FORMAT_PARAMS(hr), 1987 region_gc_time_stamp, _gc_time_stamp); 1988 _failures = true; 1989 } 1990 return false; 1991 } 1992 1993 bool failures() { return _failures; } 1994 }; 1995 1996 void G1CollectedHeap::check_gc_time_stamps() { 1997 CheckGCTimeStampsHRClosure cl(_gc_time_stamp); 1998 heap_region_iterate(&cl); 1999 guarantee(!cl.failures(), "all GC time stamps should have been reset"); 2000 } 2001 #endif // PRODUCT 2002 2003 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) { 2004 _hot_card_cache->drain(cl, worker_i); 2005 } 2006 2007 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) { 2008 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 2009 size_t n_completed_buffers = 0; 2010 while (dcqs.apply_closure_during_gc(cl, worker_i)) { 2011 n_completed_buffers++; 2012 } 2013 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers); 2014 dcqs.clear_n_completed_buffers(); 2015 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!"); 2016 } 2017 2018 // Computes the sum of the storage used by the various regions. 2019 size_t G1CollectedHeap::used() const { 2020 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions(); 2021 if (_archive_allocator != NULL) { 2022 result += _archive_allocator->used(); 2023 } 2024 return result; 2025 } 2026 2027 size_t G1CollectedHeap::used_unlocked() const { 2028 return _summary_bytes_used; 2029 } 2030 2031 class SumUsedClosure: public HeapRegionClosure { 2032 size_t _used; 2033 public: 2034 SumUsedClosure() : _used(0) {} 2035 bool doHeapRegion(HeapRegion* r) { 2036 _used += r->used(); 2037 return false; 2038 } 2039 size_t result() { return _used; } 2040 }; 2041 2042 size_t G1CollectedHeap::recalculate_used() const { 2043 double recalculate_used_start = os::elapsedTime(); 2044 2045 SumUsedClosure blk; 2046 heap_region_iterate(&blk); 2047 2048 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0); 2049 return blk.result(); 2050 } 2051 2052 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) { 2053 switch (cause) { 2054 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent; 2055 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent; 2056 case GCCause::_update_allocation_context_stats_inc: return true; 2057 case GCCause::_wb_conc_mark: return true; 2058 default : return false; 2059 } 2060 } 2061 2062 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 2063 switch (cause) { 2064 case GCCause::_gc_locker: return GCLockerInvokesConcurrent; 2065 case GCCause::_g1_humongous_allocation: return true; 2066 default: return is_user_requested_concurrent_full_gc(cause); 2067 } 2068 } 2069 2070 #ifndef PRODUCT 2071 void G1CollectedHeap::allocate_dummy_regions() { 2072 // Let's fill up most of the region 2073 size_t word_size = HeapRegion::GrainWords - 1024; 2074 // And as a result the region we'll allocate will be humongous. 2075 guarantee(is_humongous(word_size), "sanity"); 2076 2077 // _filler_array_max_size is set to humongous object threshold 2078 // but temporarily change it to use CollectedHeap::fill_with_object(). 2079 SizeTFlagSetting fs(_filler_array_max_size, word_size); 2080 2081 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) { 2082 // Let's use the existing mechanism for the allocation 2083 HeapWord* dummy_obj = humongous_obj_allocate(word_size, 2084 AllocationContext::system()); 2085 if (dummy_obj != NULL) { 2086 MemRegion mr(dummy_obj, word_size); 2087 CollectedHeap::fill_with_object(mr); 2088 } else { 2089 // If we can't allocate once, we probably cannot allocate 2090 // again. Let's get out of the loop. 2091 break; 2092 } 2093 } 2094 } 2095 #endif // !PRODUCT 2096 2097 void G1CollectedHeap::increment_old_marking_cycles_started() { 2098 assert(_old_marking_cycles_started == _old_marking_cycles_completed || 2099 _old_marking_cycles_started == _old_marking_cycles_completed + 1, 2100 "Wrong marking cycle count (started: %d, completed: %d)", 2101 _old_marking_cycles_started, _old_marking_cycles_completed); 2102 2103 _old_marking_cycles_started++; 2104 } 2105 2106 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) { 2107 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 2108 2109 // We assume that if concurrent == true, then the caller is a 2110 // concurrent thread that was joined the Suspendible Thread 2111 // Set. If there's ever a cheap way to check this, we should add an 2112 // assert here. 2113 2114 // Given that this method is called at the end of a Full GC or of a 2115 // concurrent cycle, and those can be nested (i.e., a Full GC can 2116 // interrupt a concurrent cycle), the number of full collections 2117 // completed should be either one (in the case where there was no 2118 // nesting) or two (when a Full GC interrupted a concurrent cycle) 2119 // behind the number of full collections started. 2120 2121 // This is the case for the inner caller, i.e. a Full GC. 2122 assert(concurrent || 2123 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || 2124 (_old_marking_cycles_started == _old_marking_cycles_completed + 2), 2125 "for inner caller (Full GC): _old_marking_cycles_started = %u " 2126 "is inconsistent with _old_marking_cycles_completed = %u", 2127 _old_marking_cycles_started, _old_marking_cycles_completed); 2128 2129 // This is the case for the outer caller, i.e. the concurrent cycle. 2130 assert(!concurrent || 2131 (_old_marking_cycles_started == _old_marking_cycles_completed + 1), 2132 "for outer caller (concurrent cycle): " 2133 "_old_marking_cycles_started = %u " 2134 "is inconsistent with _old_marking_cycles_completed = %u", 2135 _old_marking_cycles_started, _old_marking_cycles_completed); 2136 2137 _old_marking_cycles_completed += 1; 2138 2139 // We need to clear the "in_progress" flag in the CM thread before 2140 // we wake up any waiters (especially when ExplicitInvokesConcurrent 2141 // is set) so that if a waiter requests another System.gc() it doesn't 2142 // incorrectly see that a marking cycle is still in progress. 2143 if (concurrent) { 2144 _cmThread->set_idle(); 2145 } 2146 2147 // This notify_all() will ensure that a thread that called 2148 // System.gc() with (with ExplicitGCInvokesConcurrent set or not) 2149 // and it's waiting for a full GC to finish will be woken up. It is 2150 // waiting in VM_G1IncCollectionPause::doit_epilogue(). 2151 FullGCCount_lock->notify_all(); 2152 } 2153 2154 void G1CollectedHeap::collect(GCCause::Cause cause) { 2155 assert_heap_not_locked(); 2156 2157 uint gc_count_before; 2158 uint old_marking_count_before; 2159 uint full_gc_count_before; 2160 bool retry_gc; 2161 2162 do { 2163 retry_gc = false; 2164 2165 { 2166 MutexLocker ml(Heap_lock); 2167 2168 // Read the GC count while holding the Heap_lock 2169 gc_count_before = total_collections(); 2170 full_gc_count_before = total_full_collections(); 2171 old_marking_count_before = _old_marking_cycles_started; 2172 } 2173 2174 if (should_do_concurrent_full_gc(cause)) { 2175 // Schedule an initial-mark evacuation pause that will start a 2176 // concurrent cycle. We're setting word_size to 0 which means that 2177 // we are not requesting a post-GC allocation. 2178 VM_G1IncCollectionPause op(gc_count_before, 2179 0, /* word_size */ 2180 true, /* should_initiate_conc_mark */ 2181 g1_policy()->max_pause_time_ms(), 2182 cause); 2183 op.set_allocation_context(AllocationContext::current()); 2184 2185 VMThread::execute(&op); 2186 if (!op.pause_succeeded()) { 2187 if (old_marking_count_before == _old_marking_cycles_started) { 2188 retry_gc = op.should_retry_gc(); 2189 } else { 2190 // A Full GC happened while we were trying to schedule the 2191 // initial-mark GC. No point in starting a new cycle given 2192 // that the whole heap was collected anyway. 2193 } 2194 2195 if (retry_gc) { 2196 if (GCLocker::is_active_and_needs_gc()) { 2197 GCLocker::stall_until_clear(); 2198 } 2199 } 2200 } 2201 } else { 2202 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc 2203 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { 2204 2205 // Schedule a standard evacuation pause. We're setting word_size 2206 // to 0 which means that we are not requesting a post-GC allocation. 2207 VM_G1IncCollectionPause op(gc_count_before, 2208 0, /* word_size */ 2209 false, /* should_initiate_conc_mark */ 2210 g1_policy()->max_pause_time_ms(), 2211 cause); 2212 VMThread::execute(&op); 2213 } else { 2214 // Schedule a Full GC. 2215 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause); 2216 VMThread::execute(&op); 2217 } 2218 } 2219 } while (retry_gc); 2220 } 2221 2222 bool G1CollectedHeap::is_in(const void* p) const { 2223 if (_hrm.reserved().contains(p)) { 2224 // Given that we know that p is in the reserved space, 2225 // heap_region_containing() should successfully 2226 // return the containing region. 2227 HeapRegion* hr = heap_region_containing(p); 2228 return hr->is_in(p); 2229 } else { 2230 return false; 2231 } 2232 } 2233 2234 #ifdef ASSERT 2235 bool G1CollectedHeap::is_in_exact(const void* p) const { 2236 bool contains = reserved_region().contains(p); 2237 bool available = _hrm.is_available(addr_to_region((HeapWord*)p)); 2238 if (contains && available) { 2239 return true; 2240 } else { 2241 return false; 2242 } 2243 } 2244 #endif 2245 2246 // Iteration functions. 2247 2248 // Iterates an ObjectClosure over all objects within a HeapRegion. 2249 2250 class IterateObjectClosureRegionClosure: public HeapRegionClosure { 2251 ObjectClosure* _cl; 2252 public: 2253 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} 2254 bool doHeapRegion(HeapRegion* r) { 2255 if (!r->is_continues_humongous()) { 2256 r->object_iterate(_cl); 2257 } 2258 return false; 2259 } 2260 }; 2261 2262 void G1CollectedHeap::object_iterate(ObjectClosure* cl) { 2263 IterateObjectClosureRegionClosure blk(cl); 2264 heap_region_iterate(&blk); 2265 } 2266 2267 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { 2268 _hrm.iterate(cl); 2269 } 2270 2271 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl, 2272 HeapRegionClaimer *hrclaimer, 2273 uint worker_id) const { 2274 _hrm.par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id)); 2275 } 2276 2277 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl, 2278 HeapRegionClaimer *hrclaimer) const { 2279 _hrm.par_iterate(cl, hrclaimer, 0); 2280 } 2281 2282 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) { 2283 _collection_set.iterate(cl); 2284 } 2285 2286 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) { 2287 _collection_set.iterate_from(cl, worker_id, workers()->active_workers()); 2288 } 2289 2290 HeapWord* G1CollectedHeap::block_start(const void* addr) const { 2291 HeapRegion* hr = heap_region_containing(addr); 2292 return hr->block_start(addr); 2293 } 2294 2295 size_t G1CollectedHeap::block_size(const HeapWord* addr) const { 2296 HeapRegion* hr = heap_region_containing(addr); 2297 return hr->block_size(addr); 2298 } 2299 2300 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { 2301 HeapRegion* hr = heap_region_containing(addr); 2302 return hr->block_is_obj(addr); 2303 } 2304 2305 bool G1CollectedHeap::supports_tlab_allocation() const { 2306 return true; 2307 } 2308 2309 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { 2310 return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes; 2311 } 2312 2313 size_t G1CollectedHeap::tlab_used(Thread* ignored) const { 2314 return _eden.length() * HeapRegion::GrainBytes; 2315 } 2316 2317 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size 2318 // must be equal to the humongous object limit. 2319 size_t G1CollectedHeap::max_tlab_size() const { 2320 return align_down(_humongous_object_threshold_in_words, MinObjAlignment); 2321 } 2322 2323 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { 2324 AllocationContext_t context = AllocationContext::current(); 2325 return _allocator->unsafe_max_tlab_alloc(context); 2326 } 2327 2328 size_t G1CollectedHeap::max_capacity() const { 2329 return _hrm.reserved().byte_size(); 2330 } 2331 2332 jlong G1CollectedHeap::millis_since_last_gc() { 2333 // See the notes in GenCollectedHeap::millis_since_last_gc() 2334 // for more information about the implementation. 2335 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) - 2336 _g1_policy->collection_pause_end_millis(); 2337 if (ret_val < 0) { 2338 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT 2339 ". returning zero instead.", ret_val); 2340 return 0; 2341 } 2342 return ret_val; 2343 } 2344 2345 void G1CollectedHeap::prepare_for_verify() { 2346 _verifier->prepare_for_verify(); 2347 } 2348 2349 void G1CollectedHeap::verify(VerifyOption vo) { 2350 _verifier->verify(vo); 2351 } 2352 2353 bool G1CollectedHeap::supports_concurrent_phase_control() const { 2354 return true; 2355 } 2356 2357 const char* const* G1CollectedHeap::concurrent_phases() const { 2358 return _cmThread->concurrent_phases(); 2359 } 2360 2361 bool G1CollectedHeap::request_concurrent_phase(const char* phase) { 2362 return _cmThread->request_concurrent_phase(phase); 2363 } 2364 2365 class PrintRegionClosure: public HeapRegionClosure { 2366 outputStream* _st; 2367 public: 2368 PrintRegionClosure(outputStream* st) : _st(st) {} 2369 bool doHeapRegion(HeapRegion* r) { 2370 r->print_on(_st); 2371 return false; 2372 } 2373 }; 2374 2375 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2376 const HeapRegion* hr, 2377 const VerifyOption vo) const { 2378 switch (vo) { 2379 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); 2380 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); 2381 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr); 2382 default: ShouldNotReachHere(); 2383 } 2384 return false; // keep some compilers happy 2385 } 2386 2387 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2388 const VerifyOption vo) const { 2389 switch (vo) { 2390 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); 2391 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); 2392 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj); 2393 default: ShouldNotReachHere(); 2394 } 2395 return false; // keep some compilers happy 2396 } 2397 2398 void G1CollectedHeap::print_heap_regions() const { 2399 LogTarget(Trace, gc, heap, region) lt; 2400 if (lt.is_enabled()) { 2401 LogStream ls(lt); 2402 print_regions_on(&ls); 2403 } 2404 } 2405 2406 void G1CollectedHeap::print_on(outputStream* st) const { 2407 st->print(" %-20s", "garbage-first heap"); 2408 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 2409 capacity()/K, used_unlocked()/K); 2410 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")", 2411 p2i(_hrm.reserved().start()), 2412 p2i(_hrm.reserved().end())); 2413 st->cr(); 2414 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); 2415 uint young_regions = young_regions_count(); 2416 st->print("%u young (" SIZE_FORMAT "K), ", young_regions, 2417 (size_t) young_regions * HeapRegion::GrainBytes / K); 2418 uint survivor_regions = survivor_regions_count(); 2419 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, 2420 (size_t) survivor_regions * HeapRegion::GrainBytes / K); 2421 st->cr(); 2422 MetaspaceAux::print_on(st); 2423 } 2424 2425 void G1CollectedHeap::print_regions_on(outputStream* st) const { 2426 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, " 2427 "HS=humongous(starts), HC=humongous(continues), " 2428 "CS=collection set, F=free, A=archive, TS=gc time stamp, " 2429 "AC=allocation context, " 2430 "TAMS=top-at-mark-start (previous, next)"); 2431 PrintRegionClosure blk(st); 2432 heap_region_iterate(&blk); 2433 } 2434 2435 void G1CollectedHeap::print_extended_on(outputStream* st) const { 2436 print_on(st); 2437 2438 // Print the per-region information. 2439 print_regions_on(st); 2440 } 2441 2442 void G1CollectedHeap::print_on_error(outputStream* st) const { 2443 this->CollectedHeap::print_on_error(st); 2444 2445 if (_cm != NULL) { 2446 st->cr(); 2447 _cm->print_on_error(st); 2448 } 2449 } 2450 2451 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const { 2452 workers()->print_worker_threads_on(st); 2453 _cmThread->print_on(st); 2454 st->cr(); 2455 _cm->print_worker_threads_on(st); 2456 _cr->print_threads_on(st); 2457 _young_gen_sampling_thread->print_on(st); 2458 if (G1StringDedup::is_enabled()) { 2459 G1StringDedup::print_worker_threads_on(st); 2460 } 2461 } 2462 2463 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { 2464 workers()->threads_do(tc); 2465 tc->do_thread(_cmThread); 2466 _cm->threads_do(tc); 2467 _cr->threads_do(tc); 2468 tc->do_thread(_young_gen_sampling_thread); 2469 if (G1StringDedup::is_enabled()) { 2470 G1StringDedup::threads_do(tc); 2471 } 2472 } 2473 2474 void G1CollectedHeap::print_tracing_info() const { 2475 g1_rem_set()->print_summary_info(); 2476 concurrent_mark()->print_summary_info(); 2477 } 2478 2479 #ifndef PRODUCT 2480 // Helpful for debugging RSet issues. 2481 2482 class PrintRSetsClosure : public HeapRegionClosure { 2483 private: 2484 const char* _msg; 2485 size_t _occupied_sum; 2486 2487 public: 2488 bool doHeapRegion(HeapRegion* r) { 2489 HeapRegionRemSet* hrrs = r->rem_set(); 2490 size_t occupied = hrrs->occupied(); 2491 _occupied_sum += occupied; 2492 2493 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r)); 2494 if (occupied == 0) { 2495 tty->print_cr(" RSet is empty"); 2496 } else { 2497 hrrs->print(); 2498 } 2499 tty->print_cr("----------"); 2500 return false; 2501 } 2502 2503 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { 2504 tty->cr(); 2505 tty->print_cr("========================================"); 2506 tty->print_cr("%s", msg); 2507 tty->cr(); 2508 } 2509 2510 ~PrintRSetsClosure() { 2511 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum); 2512 tty->print_cr("========================================"); 2513 tty->cr(); 2514 } 2515 }; 2516 2517 void G1CollectedHeap::print_cset_rsets() { 2518 PrintRSetsClosure cl("Printing CSet RSets"); 2519 collection_set_iterate(&cl); 2520 } 2521 2522 void G1CollectedHeap::print_all_rsets() { 2523 PrintRSetsClosure cl("Printing All RSets");; 2524 heap_region_iterate(&cl); 2525 } 2526 #endif // PRODUCT 2527 2528 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() { 2529 2530 size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes; 2531 size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes; 2532 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked(); 2533 2534 size_t eden_capacity_bytes = 2535 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes; 2536 2537 VirtualSpaceSummary heap_summary = create_heap_space_summary(); 2538 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes, 2539 eden_capacity_bytes, survivor_used_bytes, num_regions()); 2540 } 2541 2542 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) { 2543 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(), 2544 stats->unused(), stats->used(), stats->region_end_waste(), 2545 stats->regions_filled(), stats->direct_allocated(), 2546 stats->failure_used(), stats->failure_waste()); 2547 } 2548 2549 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) { 2550 const G1HeapSummary& heap_summary = create_g1_heap_summary(); 2551 gc_tracer->report_gc_heap_summary(when, heap_summary); 2552 2553 const MetaspaceSummary& metaspace_summary = create_metaspace_summary(); 2554 gc_tracer->report_metaspace_summary(when, metaspace_summary); 2555 } 2556 2557 G1CollectedHeap* G1CollectedHeap::heap() { 2558 CollectedHeap* heap = Universe::heap(); 2559 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()"); 2560 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap"); 2561 return (G1CollectedHeap*)heap; 2562 } 2563 2564 void G1CollectedHeap::gc_prologue(bool full) { 2565 // always_do_update_barrier = false; 2566 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 2567 2568 // This summary needs to be printed before incrementing total collections. 2569 g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections()); 2570 2571 // Update common counters. 2572 increment_total_collections(full /* full gc */); 2573 if (full) { 2574 increment_old_marking_cycles_started(); 2575 reset_gc_time_stamp(); 2576 } else { 2577 increment_gc_time_stamp(); 2578 } 2579 2580 // Fill TLAB's and such 2581 double start = os::elapsedTime(); 2582 accumulate_statistics_all_tlabs(); 2583 ensure_parsability(true); 2584 g1_policy()->phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0); 2585 } 2586 2587 void G1CollectedHeap::gc_epilogue(bool full) { 2588 // Update common counters. 2589 if (full) { 2590 // Update the number of full collections that have been completed. 2591 increment_old_marking_cycles_completed(false /* concurrent */); 2592 } 2593 2594 // We are at the end of the GC. Total collections has already been increased. 2595 g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1); 2596 2597 // FIXME: what is this about? 2598 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" 2599 // is set. 2600 #if COMPILER2_OR_JVMCI 2601 assert(DerivedPointerTable::is_empty(), "derived pointer present"); 2602 #endif 2603 // always_do_update_barrier = true; 2604 2605 double start = os::elapsedTime(); 2606 resize_all_tlabs(); 2607 g1_policy()->phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0); 2608 2609 allocation_context_stats().update(full); 2610 2611 MemoryService::track_memory_usage(); 2612 // We have just completed a GC. Update the soft reference 2613 // policy with the new heap occupancy 2614 Universe::update_heap_info_at_gc(); 2615 } 2616 2617 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, 2618 uint gc_count_before, 2619 bool* succeeded, 2620 GCCause::Cause gc_cause) { 2621 assert_heap_not_locked_and_not_at_safepoint(); 2622 VM_G1IncCollectionPause op(gc_count_before, 2623 word_size, 2624 false, /* should_initiate_conc_mark */ 2625 g1_policy()->max_pause_time_ms(), 2626 gc_cause); 2627 2628 op.set_allocation_context(AllocationContext::current()); 2629 VMThread::execute(&op); 2630 2631 HeapWord* result = op.result(); 2632 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded(); 2633 assert(result == NULL || ret_succeeded, 2634 "the result should be NULL if the VM did not succeed"); 2635 *succeeded = ret_succeeded; 2636 2637 assert_heap_not_locked(); 2638 return result; 2639 } 2640 2641 void 2642 G1CollectedHeap::doConcurrentMark() { 2643 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); 2644 if (!_cmThread->in_progress()) { 2645 _cmThread->set_started(); 2646 CGC_lock->notify(); 2647 } 2648 } 2649 2650 size_t G1CollectedHeap::pending_card_num() { 2651 size_t extra_cards = 0; 2652 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *curr = jtiwh.next(); ) { 2653 DirtyCardQueue& dcq = curr->dirty_card_queue(); 2654 extra_cards += dcq.size(); 2655 } 2656 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 2657 size_t buffer_size = dcqs.buffer_size(); 2658 size_t buffer_num = dcqs.completed_buffers_num(); 2659 2660 return buffer_size * buffer_num + extra_cards; 2661 } 2662 2663 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure { 2664 private: 2665 size_t _total_humongous; 2666 size_t _candidate_humongous; 2667 2668 DirtyCardQueue _dcq; 2669 2670 // We don't nominate objects with many remembered set entries, on 2671 // the assumption that such objects are likely still live. 2672 bool is_remset_small(HeapRegion* region) const { 2673 HeapRegionRemSet* const rset = region->rem_set(); 2674 return G1EagerReclaimHumongousObjectsWithStaleRefs 2675 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) 2676 : rset->is_empty(); 2677 } 2678 2679 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const { 2680 assert(region->is_starts_humongous(), "Must start a humongous object"); 2681 2682 oop obj = oop(region->bottom()); 2683 2684 // Dead objects cannot be eager reclaim candidates. Due to class 2685 // unloading it is unsafe to query their classes so we return early. 2686 if (heap->is_obj_dead(obj, region)) { 2687 return false; 2688 } 2689 2690 // Candidate selection must satisfy the following constraints 2691 // while concurrent marking is in progress: 2692 // 2693 // * In order to maintain SATB invariants, an object must not be 2694 // reclaimed if it was allocated before the start of marking and 2695 // has not had its references scanned. Such an object must have 2696 // its references (including type metadata) scanned to ensure no 2697 // live objects are missed by the marking process. Objects 2698 // allocated after the start of concurrent marking don't need to 2699 // be scanned. 2700 // 2701 // * An object must not be reclaimed if it is on the concurrent 2702 // mark stack. Objects allocated after the start of concurrent 2703 // marking are never pushed on the mark stack. 2704 // 2705 // Nominating only objects allocated after the start of concurrent 2706 // marking is sufficient to meet both constraints. This may miss 2707 // some objects that satisfy the constraints, but the marking data 2708 // structures don't support efficiently performing the needed 2709 // additional tests or scrubbing of the mark stack. 2710 // 2711 // However, we presently only nominate is_typeArray() objects. 2712 // A humongous object containing references induces remembered 2713 // set entries on other regions. In order to reclaim such an 2714 // object, those remembered sets would need to be cleaned up. 2715 // 2716 // We also treat is_typeArray() objects specially, allowing them 2717 // to be reclaimed even if allocated before the start of 2718 // concurrent mark. For this we rely on mark stack insertion to 2719 // exclude is_typeArray() objects, preventing reclaiming an object 2720 // that is in the mark stack. We also rely on the metadata for 2721 // such objects to be built-in and so ensured to be kept live. 2722 // Frequent allocation and drop of large binary blobs is an 2723 // important use case for eager reclaim, and this special handling 2724 // may reduce needed headroom. 2725 2726 return obj->is_typeArray() && is_remset_small(region); 2727 } 2728 2729 public: 2730 RegisterHumongousWithInCSetFastTestClosure() 2731 : _total_humongous(0), 2732 _candidate_humongous(0), 2733 _dcq(&JavaThread::dirty_card_queue_set()) { 2734 } 2735 2736 virtual bool doHeapRegion(HeapRegion* r) { 2737 if (!r->is_starts_humongous()) { 2738 return false; 2739 } 2740 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 2741 2742 bool is_candidate = humongous_region_is_candidate(g1h, r); 2743 uint rindex = r->hrm_index(); 2744 g1h->set_humongous_reclaim_candidate(rindex, is_candidate); 2745 if (is_candidate) { 2746 _candidate_humongous++; 2747 g1h->register_humongous_region_with_cset(rindex); 2748 // Is_candidate already filters out humongous object with large remembered sets. 2749 // If we have a humongous object with a few remembered sets, we simply flush these 2750 // remembered set entries into the DCQS. That will result in automatic 2751 // re-evaluation of their remembered set entries during the following evacuation 2752 // phase. 2753 if (!r->rem_set()->is_empty()) { 2754 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries), 2755 "Found a not-small remembered set here. This is inconsistent with previous assumptions."); 2756 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set(); 2757 HeapRegionRemSetIterator hrrs(r->rem_set()); 2758 size_t card_index; 2759 while (hrrs.has_next(card_index)) { 2760 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index); 2761 // The remembered set might contain references to already freed 2762 // regions. Filter out such entries to avoid failing card table 2763 // verification. 2764 if (g1h->is_in_closed_subset(bs->addr_for(card_ptr))) { 2765 if (*card_ptr != CardTableModRefBS::dirty_card_val()) { 2766 *card_ptr = CardTableModRefBS::dirty_card_val(); 2767 _dcq.enqueue(card_ptr); 2768 } 2769 } 2770 } 2771 assert(hrrs.n_yielded() == r->rem_set()->occupied(), 2772 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries", 2773 hrrs.n_yielded(), r->rem_set()->occupied()); 2774 r->rem_set()->clear_locked(); 2775 } 2776 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty."); 2777 } 2778 _total_humongous++; 2779 2780 return false; 2781 } 2782 2783 size_t total_humongous() const { return _total_humongous; } 2784 size_t candidate_humongous() const { return _candidate_humongous; } 2785 2786 void flush_rem_set_entries() { _dcq.flush(); } 2787 }; 2788 2789 void G1CollectedHeap::register_humongous_regions_with_cset() { 2790 if (!G1EagerReclaimHumongousObjects) { 2791 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0); 2792 return; 2793 } 2794 double time = os::elapsed_counter(); 2795 2796 // Collect reclaim candidate information and register candidates with cset. 2797 RegisterHumongousWithInCSetFastTestClosure cl; 2798 heap_region_iterate(&cl); 2799 2800 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0; 2801 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time, 2802 cl.total_humongous(), 2803 cl.candidate_humongous()); 2804 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0; 2805 2806 // Finally flush all remembered set entries to re-check into the global DCQS. 2807 cl.flush_rem_set_entries(); 2808 } 2809 2810 class VerifyRegionRemSetClosure : public HeapRegionClosure { 2811 public: 2812 bool doHeapRegion(HeapRegion* hr) { 2813 if (!hr->is_archive() && !hr->is_continues_humongous()) { 2814 hr->verify_rem_set(); 2815 } 2816 return false; 2817 } 2818 }; 2819 2820 uint G1CollectedHeap::num_task_queues() const { 2821 return _task_queues->size(); 2822 } 2823 2824 #if TASKQUEUE_STATS 2825 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) { 2826 st->print_raw_cr("GC Task Stats"); 2827 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); 2828 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); 2829 } 2830 2831 void G1CollectedHeap::print_taskqueue_stats() const { 2832 if (!log_is_enabled(Trace, gc, task, stats)) { 2833 return; 2834 } 2835 Log(gc, task, stats) log; 2836 ResourceMark rm; 2837 LogStream ls(log.trace()); 2838 outputStream* st = &ls; 2839 2840 print_taskqueue_stats_hdr(st); 2841 2842 TaskQueueStats totals; 2843 const uint n = num_task_queues(); 2844 for (uint i = 0; i < n; ++i) { 2845 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr(); 2846 totals += task_queue(i)->stats; 2847 } 2848 st->print_raw("tot "); totals.print(st); st->cr(); 2849 2850 DEBUG_ONLY(totals.verify()); 2851 } 2852 2853 void G1CollectedHeap::reset_taskqueue_stats() { 2854 const uint n = num_task_queues(); 2855 for (uint i = 0; i < n; ++i) { 2856 task_queue(i)->stats.reset(); 2857 } 2858 } 2859 #endif // TASKQUEUE_STATS 2860 2861 void G1CollectedHeap::wait_for_root_region_scanning() { 2862 double scan_wait_start = os::elapsedTime(); 2863 // We have to wait until the CM threads finish scanning the 2864 // root regions as it's the only way to ensure that all the 2865 // objects on them have been correctly scanned before we start 2866 // moving them during the GC. 2867 bool waited = _cm->root_regions()->wait_until_scan_finished(); 2868 double wait_time_ms = 0.0; 2869 if (waited) { 2870 double scan_wait_end = os::elapsedTime(); 2871 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0; 2872 } 2873 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms); 2874 } 2875 2876 class G1PrintCollectionSetClosure : public HeapRegionClosure { 2877 private: 2878 G1HRPrinter* _hr_printer; 2879 public: 2880 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { } 2881 2882 virtual bool doHeapRegion(HeapRegion* r) { 2883 _hr_printer->cset(r); 2884 return false; 2885 } 2886 }; 2887 2888 void G1CollectedHeap::start_new_collection_set() { 2889 collection_set()->start_incremental_building(); 2890 2891 clear_cset_fast_test(); 2892 2893 guarantee(_eden.length() == 0, "eden should have been cleared"); 2894 g1_policy()->transfer_survivors_to_cset(survivor()); 2895 } 2896 2897 bool 2898 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { 2899 assert_at_safepoint(true /* should_be_vm_thread */); 2900 guarantee(!is_gc_active(), "collection is not reentrant"); 2901 2902 if (GCLocker::check_active_before_gc()) { 2903 return false; 2904 } 2905 2906 _gc_timer_stw->register_gc_start(); 2907 2908 GCIdMark gc_id_mark; 2909 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start()); 2910 2911 SvcGCMarker sgcm(SvcGCMarker::MINOR); 2912 ResourceMark rm; 2913 2914 g1_policy()->note_gc_start(); 2915 2916 wait_for_root_region_scanning(); 2917 2918 print_heap_before_gc(); 2919 print_heap_regions(); 2920 trace_heap_before_gc(_gc_tracer_stw); 2921 2922 _verifier->verify_region_sets_optional(); 2923 _verifier->verify_dirty_young_regions(); 2924 2925 // We should not be doing initial mark unless the conc mark thread is running 2926 if (!_cmThread->should_terminate()) { 2927 // This call will decide whether this pause is an initial-mark 2928 // pause. If it is, during_initial_mark_pause() will return true 2929 // for the duration of this pause. 2930 g1_policy()->decide_on_conc_mark_initiation(); 2931 } 2932 2933 // We do not allow initial-mark to be piggy-backed on a mixed GC. 2934 assert(!collector_state()->during_initial_mark_pause() || 2935 collector_state()->gcs_are_young(), "sanity"); 2936 2937 // We also do not allow mixed GCs during marking. 2938 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity"); 2939 2940 // Record whether this pause is an initial mark. When the current 2941 // thread has completed its logging output and it's safe to signal 2942 // the CM thread, the flag's value in the policy has been reset. 2943 bool should_start_conc_mark = collector_state()->during_initial_mark_pause(); 2944 2945 // Inner scope for scope based logging, timers, and stats collection 2946 { 2947 EvacuationInfo evacuation_info; 2948 2949 if (collector_state()->during_initial_mark_pause()) { 2950 // We are about to start a marking cycle, so we increment the 2951 // full collection counter. 2952 increment_old_marking_cycles_started(); 2953 _cm->gc_tracer_cm()->set_gc_cause(gc_cause()); 2954 } 2955 2956 _gc_tracer_stw->report_yc_type(collector_state()->yc_type()); 2957 2958 GCTraceCPUTime tcpu; 2959 2960 G1HeapVerifier::G1VerifyType verify_type; 2961 FormatBuffer<> gc_string("Pause "); 2962 if (collector_state()->during_initial_mark_pause()) { 2963 gc_string.append("Initial Mark"); 2964 verify_type = G1HeapVerifier::G1VerifyInitialMark; 2965 } else if (collector_state()->gcs_are_young()) { 2966 gc_string.append("Young"); 2967 verify_type = G1HeapVerifier::G1VerifyYoungOnly; 2968 } else { 2969 gc_string.append("Mixed"); 2970 verify_type = G1HeapVerifier::G1VerifyMixed; 2971 } 2972 GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true); 2973 2974 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 2975 workers()->active_workers(), 2976 Threads::number_of_non_daemon_threads()); 2977 workers()->update_active_workers(active_workers); 2978 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers()); 2979 2980 TraceCollectorStats tcs(g1mm()->incremental_collection_counters()); 2981 TraceMemoryManagerStats tms(&_memory_manager, gc_cause()); 2982 2983 // If the secondary_free_list is not empty, append it to the 2984 // free_list. No need to wait for the cleanup operation to finish; 2985 // the region allocation code will check the secondary_free_list 2986 // and wait if necessary. If the G1StressConcRegionFreeing flag is 2987 // set, skip this step so that the region allocation code has to 2988 // get entries from the secondary_free_list. 2989 if (!G1StressConcRegionFreeing) { 2990 append_secondary_free_list_if_not_empty_with_lock(); 2991 } 2992 2993 G1HeapTransition heap_transition(this); 2994 size_t heap_used_bytes_before_gc = used(); 2995 2996 // Don't dynamically change the number of GC threads this early. A value of 2997 // 0 is used to indicate serial work. When parallel work is done, 2998 // it will be set. 2999 3000 { // Call to jvmpi::post_class_unload_events must occur outside of active GC 3001 IsGCActiveMark x; 3002 3003 gc_prologue(false); 3004 3005 if (VerifyRememberedSets) { 3006 log_info(gc, verify)("[Verifying RemSets before GC]"); 3007 VerifyRegionRemSetClosure v_cl; 3008 heap_region_iterate(&v_cl); 3009 } 3010 3011 _verifier->verify_before_gc(verify_type); 3012 3013 _verifier->check_bitmaps("GC Start"); 3014 3015 #if COMPILER2_OR_JVMCI 3016 DerivedPointerTable::clear(); 3017 #endif 3018 3019 // Please see comment in g1CollectedHeap.hpp and 3020 // G1CollectedHeap::ref_processing_init() to see how 3021 // reference processing currently works in G1. 3022 3023 // Enable discovery in the STW reference processor 3024 if (g1_policy()->should_process_references()) { 3025 ref_processor_stw()->enable_discovery(); 3026 } else { 3027 ref_processor_stw()->disable_discovery(); 3028 } 3029 3030 { 3031 // We want to temporarily turn off discovery by the 3032 // CM ref processor, if necessary, and turn it back on 3033 // on again later if we do. Using a scoped 3034 // NoRefDiscovery object will do this. 3035 NoRefDiscovery no_cm_discovery(ref_processor_cm()); 3036 3037 // Forget the current alloc region (we might even choose it to be part 3038 // of the collection set!). 3039 _allocator->release_mutator_alloc_region(); 3040 3041 // This timing is only used by the ergonomics to handle our pause target. 3042 // It is unclear why this should not include the full pause. We will 3043 // investigate this in CR 7178365. 3044 // 3045 // Preserving the old comment here if that helps the investigation: 3046 // 3047 // The elapsed time induced by the start time below deliberately elides 3048 // the possible verification above. 3049 double sample_start_time_sec = os::elapsedTime(); 3050 3051 g1_policy()->record_collection_pause_start(sample_start_time_sec); 3052 3053 if (collector_state()->during_initial_mark_pause()) { 3054 concurrent_mark()->checkpoint_roots_initial_pre(); 3055 } 3056 3057 g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor); 3058 3059 evacuation_info.set_collectionset_regions(collection_set()->region_length()); 3060 3061 // Make sure the remembered sets are up to date. This needs to be 3062 // done before register_humongous_regions_with_cset(), because the 3063 // remembered sets are used there to choose eager reclaim candidates. 3064 // If the remembered sets are not up to date we might miss some 3065 // entries that need to be handled. 3066 g1_rem_set()->cleanupHRRS(); 3067 3068 register_humongous_regions_with_cset(); 3069 3070 assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table."); 3071 3072 // We call this after finalize_cset() to 3073 // ensure that the CSet has been finalized. 3074 _cm->verify_no_cset_oops(); 3075 3076 if (_hr_printer.is_active()) { 3077 G1PrintCollectionSetClosure cl(&_hr_printer); 3078 _collection_set.iterate(&cl); 3079 } 3080 3081 // Initialize the GC alloc regions. 3082 _allocator->init_gc_alloc_regions(evacuation_info); 3083 3084 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length()); 3085 pre_evacuate_collection_set(); 3086 3087 // Actually do the work... 3088 evacuate_collection_set(evacuation_info, &per_thread_states); 3089 3090 post_evacuate_collection_set(evacuation_info, &per_thread_states); 3091 3092 const size_t* surviving_young_words = per_thread_states.surviving_young_words(); 3093 free_collection_set(&_collection_set, evacuation_info, surviving_young_words); 3094 3095 eagerly_reclaim_humongous_regions(); 3096 3097 record_obj_copy_mem_stats(); 3098 _survivor_evac_stats.adjust_desired_plab_sz(); 3099 _old_evac_stats.adjust_desired_plab_sz(); 3100 3101 double start = os::elapsedTime(); 3102 start_new_collection_set(); 3103 g1_policy()->phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0); 3104 3105 if (evacuation_failed()) { 3106 set_used(recalculate_used()); 3107 if (_archive_allocator != NULL) { 3108 _archive_allocator->clear_used(); 3109 } 3110 for (uint i = 0; i < ParallelGCThreads; i++) { 3111 if (_evacuation_failed_info_array[i].has_failed()) { 3112 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]); 3113 } 3114 } 3115 } else { 3116 // The "used" of the the collection set have already been subtracted 3117 // when they were freed. Add in the bytes evacuated. 3118 increase_used(g1_policy()->bytes_copied_during_gc()); 3119 } 3120 3121 if (collector_state()->during_initial_mark_pause()) { 3122 // We have to do this before we notify the CM threads that 3123 // they can start working to make sure that all the 3124 // appropriate initialization is done on the CM object. 3125 concurrent_mark()->checkpoint_roots_initial_post(); 3126 collector_state()->set_mark_in_progress(true); 3127 // Note that we don't actually trigger the CM thread at 3128 // this point. We do that later when we're sure that 3129 // the current thread has completed its logging output. 3130 } 3131 3132 allocate_dummy_regions(); 3133 3134 _allocator->init_mutator_alloc_region(); 3135 3136 { 3137 size_t expand_bytes = _heap_sizing_policy->expansion_amount(); 3138 if (expand_bytes > 0) { 3139 size_t bytes_before = capacity(); 3140 // No need for an ergo logging here, 3141 // expansion_amount() does this when it returns a value > 0. 3142 double expand_ms; 3143 if (!expand(expand_bytes, _workers, &expand_ms)) { 3144 // We failed to expand the heap. Cannot do anything about it. 3145 } 3146 g1_policy()->phase_times()->record_expand_heap_time(expand_ms); 3147 } 3148 } 3149 3150 // We redo the verification but now wrt to the new CSet which 3151 // has just got initialized after the previous CSet was freed. 3152 _cm->verify_no_cset_oops(); 3153 3154 // This timing is only used by the ergonomics to handle our pause target. 3155 // It is unclear why this should not include the full pause. We will 3156 // investigate this in CR 7178365. 3157 double sample_end_time_sec = os::elapsedTime(); 3158 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; 3159 size_t total_cards_scanned = g1_policy()->phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScanRSScannedCards); 3160 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc); 3161 3162 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before()); 3163 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc()); 3164 3165 if (VerifyRememberedSets) { 3166 log_info(gc, verify)("[Verifying RemSets after GC]"); 3167 VerifyRegionRemSetClosure v_cl; 3168 heap_region_iterate(&v_cl); 3169 } 3170 3171 _verifier->verify_after_gc(verify_type); 3172 _verifier->check_bitmaps("GC End"); 3173 3174 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 3175 ref_processor_stw()->verify_no_references_recorded(); 3176 3177 // CM reference discovery will be re-enabled if necessary. 3178 } 3179 3180 #ifdef TRACESPINNING 3181 ParallelTaskTerminator::print_termination_counts(); 3182 #endif 3183 3184 gc_epilogue(false); 3185 } 3186 3187 // Print the remainder of the GC log output. 3188 if (evacuation_failed()) { 3189 log_info(gc)("To-space exhausted"); 3190 } 3191 3192 g1_policy()->print_phases(); 3193 heap_transition.print(); 3194 3195 // It is not yet to safe to tell the concurrent mark to 3196 // start as we have some optional output below. We don't want the 3197 // output from the concurrent mark thread interfering with this 3198 // logging output either. 3199 3200 _hrm.verify_optional(); 3201 _verifier->verify_region_sets_optional(); 3202 3203 TASKQUEUE_STATS_ONLY(print_taskqueue_stats()); 3204 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); 3205 3206 print_heap_after_gc(); 3207 print_heap_regions(); 3208 trace_heap_after_gc(_gc_tracer_stw); 3209 3210 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 3211 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 3212 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 3213 // before any GC notifications are raised. 3214 g1mm()->update_sizes(); 3215 3216 _gc_tracer_stw->report_evacuation_info(&evacuation_info); 3217 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold()); 3218 _gc_timer_stw->register_gc_end(); 3219 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions()); 3220 } 3221 // It should now be safe to tell the concurrent mark thread to start 3222 // without its logging output interfering with the logging output 3223 // that came from the pause. 3224 3225 if (should_start_conc_mark) { 3226 // CAUTION: after the doConcurrentMark() call below, 3227 // the concurrent marking thread(s) could be running 3228 // concurrently with us. Make sure that anything after 3229 // this point does not assume that we are the only GC thread 3230 // running. Note: of course, the actual marking work will 3231 // not start until the safepoint itself is released in 3232 // SuspendibleThreadSet::desynchronize(). 3233 doConcurrentMark(); 3234 } 3235 3236 return true; 3237 } 3238 3239 void G1CollectedHeap::remove_self_forwarding_pointers() { 3240 G1ParRemoveSelfForwardPtrsTask rsfp_task; 3241 workers()->run_task(&rsfp_task); 3242 } 3243 3244 void G1CollectedHeap::restore_after_evac_failure() { 3245 double remove_self_forwards_start = os::elapsedTime(); 3246 3247 remove_self_forwarding_pointers(); 3248 SharedRestorePreservedMarksTaskExecutor task_executor(workers()); 3249 _preserved_marks_set.restore(&task_executor); 3250 3251 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0); 3252 } 3253 3254 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) { 3255 if (!_evacuation_failed) { 3256 _evacuation_failed = true; 3257 } 3258 3259 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size()); 3260 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m); 3261 } 3262 3263 bool G1ParEvacuateFollowersClosure::offer_termination() { 3264 G1ParScanThreadState* const pss = par_scan_state(); 3265 start_term_time(); 3266 const bool res = terminator()->offer_termination(); 3267 end_term_time(); 3268 return res; 3269 } 3270 3271 void G1ParEvacuateFollowersClosure::do_void() { 3272 G1ParScanThreadState* const pss = par_scan_state(); 3273 pss->trim_queue(); 3274 do { 3275 pss->steal_and_trim_queue(queues()); 3276 } while (!offer_termination()); 3277 } 3278 3279 class G1ParTask : public AbstractGangTask { 3280 protected: 3281 G1CollectedHeap* _g1h; 3282 G1ParScanThreadStateSet* _pss; 3283 RefToScanQueueSet* _queues; 3284 G1RootProcessor* _root_processor; 3285 ParallelTaskTerminator _terminator; 3286 uint _n_workers; 3287 3288 public: 3289 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers) 3290 : AbstractGangTask("G1 collection"), 3291 _g1h(g1h), 3292 _pss(per_thread_states), 3293 _queues(task_queues), 3294 _root_processor(root_processor), 3295 _terminator(n_workers, _queues), 3296 _n_workers(n_workers) 3297 {} 3298 3299 void work(uint worker_id) { 3300 if (worker_id >= _n_workers) return; // no work needed this round 3301 3302 double start_sec = os::elapsedTime(); 3303 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec); 3304 3305 { 3306 ResourceMark rm; 3307 HandleMark hm; 3308 3309 ReferenceProcessor* rp = _g1h->ref_processor_stw(); 3310 3311 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 3312 pss->set_ref_processor(rp); 3313 3314 double start_strong_roots_sec = os::elapsedTime(); 3315 3316 _root_processor->evacuate_roots(pss->closures(), worker_id); 3317 3318 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid 3319 // treating the nmethods visited to act as roots for concurrent marking. 3320 // We only want to make sure that the oops in the nmethods are adjusted with regard to the 3321 // objects copied by the current evacuation. 3322 _g1h->g1_rem_set()->oops_into_collection_set_do(pss, 3323 pss->closures()->weak_codeblobs(), 3324 worker_id); 3325 3326 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec; 3327 3328 double term_sec = 0.0; 3329 size_t evac_term_attempts = 0; 3330 { 3331 double start = os::elapsedTime(); 3332 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator); 3333 evac.do_void(); 3334 3335 evac_term_attempts = evac.term_attempts(); 3336 term_sec = evac.term_time(); 3337 double elapsed_sec = os::elapsedTime() - start; 3338 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec); 3339 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec); 3340 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts); 3341 } 3342 3343 assert(pss->queue_is_empty(), "should be empty"); 3344 3345 if (log_is_enabled(Debug, gc, task, stats)) { 3346 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); 3347 size_t lab_waste; 3348 size_t lab_undo_waste; 3349 pss->waste(lab_waste, lab_undo_waste); 3350 _g1h->print_termination_stats(worker_id, 3351 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */ 3352 strong_roots_sec * 1000.0, /* strong roots time */ 3353 term_sec * 1000.0, /* evac term time */ 3354 evac_term_attempts, /* evac term attempts */ 3355 lab_waste, /* alloc buffer waste */ 3356 lab_undo_waste /* undo waste */ 3357 ); 3358 } 3359 3360 // Close the inner scope so that the ResourceMark and HandleMark 3361 // destructors are executed here and are included as part of the 3362 // "GC Worker Time". 3363 } 3364 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime()); 3365 } 3366 }; 3367 3368 void G1CollectedHeap::print_termination_stats_hdr() { 3369 log_debug(gc, task, stats)("GC Termination Stats"); 3370 log_debug(gc, task, stats)(" elapsed --strong roots-- -------termination------- ------waste (KiB)------"); 3371 log_debug(gc, task, stats)("thr ms ms %% ms %% attempts total alloc undo"); 3372 log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------"); 3373 } 3374 3375 void G1CollectedHeap::print_termination_stats(uint worker_id, 3376 double elapsed_ms, 3377 double strong_roots_ms, 3378 double term_ms, 3379 size_t term_attempts, 3380 size_t alloc_buffer_waste, 3381 size_t undo_waste) const { 3382 log_debug(gc, task, stats) 3383 ("%3d %9.2f %9.2f %6.2f " 3384 "%9.2f %6.2f " SIZE_FORMAT_W(8) " " 3385 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7), 3386 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms, 3387 term_ms, term_ms * 100 / elapsed_ms, term_attempts, 3388 (alloc_buffer_waste + undo_waste) * HeapWordSize / K, 3389 alloc_buffer_waste * HeapWordSize / K, 3390 undo_waste * HeapWordSize / K); 3391 } 3392 3393 class G1StringAndSymbolCleaningTask : public AbstractGangTask { 3394 private: 3395 BoolObjectClosure* _is_alive; 3396 G1StringDedupUnlinkOrOopsDoClosure _dedup_closure; 3397 3398 int _initial_string_table_size; 3399 int _initial_symbol_table_size; 3400 3401 bool _process_strings; 3402 int _strings_processed; 3403 int _strings_removed; 3404 3405 bool _process_symbols; 3406 int _symbols_processed; 3407 int _symbols_removed; 3408 3409 bool _process_string_dedup; 3410 3411 public: 3412 G1StringAndSymbolCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool process_string_dedup) : 3413 AbstractGangTask("String/Symbol Unlinking"), 3414 _is_alive(is_alive), 3415 _dedup_closure(is_alive, NULL, false), 3416 _process_strings(process_strings), _strings_processed(0), _strings_removed(0), 3417 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0), 3418 _process_string_dedup(process_string_dedup) { 3419 3420 _initial_string_table_size = StringTable::the_table()->table_size(); 3421 _initial_symbol_table_size = SymbolTable::the_table()->table_size(); 3422 if (process_strings) { 3423 StringTable::clear_parallel_claimed_index(); 3424 } 3425 if (process_symbols) { 3426 SymbolTable::clear_parallel_claimed_index(); 3427 } 3428 } 3429 3430 ~G1StringAndSymbolCleaningTask() { 3431 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size, 3432 "claim value %d after unlink less than initial string table size %d", 3433 StringTable::parallel_claimed_index(), _initial_string_table_size); 3434 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size, 3435 "claim value %d after unlink less than initial symbol table size %d", 3436 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size); 3437 3438 log_info(gc, stringtable)( 3439 "Cleaned string and symbol table, " 3440 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, " 3441 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed", 3442 strings_processed(), strings_removed(), 3443 symbols_processed(), symbols_removed()); 3444 } 3445 3446 void work(uint worker_id) { 3447 int strings_processed = 0; 3448 int strings_removed = 0; 3449 int symbols_processed = 0; 3450 int symbols_removed = 0; 3451 if (_process_strings) { 3452 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed); 3453 Atomic::add(strings_processed, &_strings_processed); 3454 Atomic::add(strings_removed, &_strings_removed); 3455 } 3456 if (_process_symbols) { 3457 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed); 3458 Atomic::add(symbols_processed, &_symbols_processed); 3459 Atomic::add(symbols_removed, &_symbols_removed); 3460 } 3461 if (_process_string_dedup) { 3462 G1StringDedup::parallel_unlink(&_dedup_closure, worker_id); 3463 } 3464 } 3465 3466 size_t strings_processed() const { return (size_t)_strings_processed; } 3467 size_t strings_removed() const { return (size_t)_strings_removed; } 3468 3469 size_t symbols_processed() const { return (size_t)_symbols_processed; } 3470 size_t symbols_removed() const { return (size_t)_symbols_removed; } 3471 }; 3472 3473 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC { 3474 private: 3475 static Monitor* _lock; 3476 3477 BoolObjectClosure* const _is_alive; 3478 const bool _unloading_occurred; 3479 const uint _num_workers; 3480 3481 // Variables used to claim nmethods. 3482 CompiledMethod* _first_nmethod; 3483 CompiledMethod* volatile _claimed_nmethod; 3484 3485 // The list of nmethods that need to be processed by the second pass. 3486 CompiledMethod* volatile _postponed_list; 3487 volatile uint _num_entered_barrier; 3488 3489 public: 3490 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) : 3491 _is_alive(is_alive), 3492 _unloading_occurred(unloading_occurred), 3493 _num_workers(num_workers), 3494 _first_nmethod(NULL), 3495 _claimed_nmethod(NULL), 3496 _postponed_list(NULL), 3497 _num_entered_barrier(0) 3498 { 3499 CompiledMethod::increase_unloading_clock(); 3500 // Get first alive nmethod 3501 CompiledMethodIterator iter = CompiledMethodIterator(); 3502 if(iter.next_alive()) { 3503 _first_nmethod = iter.method(); 3504 } 3505 _claimed_nmethod = _first_nmethod; 3506 } 3507 3508 ~G1CodeCacheUnloadingTask() { 3509 CodeCache::verify_clean_inline_caches(); 3510 3511 CodeCache::set_needs_cache_clean(false); 3512 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be"); 3513 3514 CodeCache::verify_icholder_relocations(); 3515 } 3516 3517 private: 3518 void add_to_postponed_list(CompiledMethod* nm) { 3519 CompiledMethod* old; 3520 do { 3521 old = _postponed_list; 3522 nm->set_unloading_next(old); 3523 } while (Atomic::cmpxchg(nm, &_postponed_list, old) != old); 3524 } 3525 3526 void clean_nmethod(CompiledMethod* nm) { 3527 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred); 3528 3529 if (postponed) { 3530 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet. 3531 add_to_postponed_list(nm); 3532 } 3533 3534 // Mark that this thread has been cleaned/unloaded. 3535 // After this call, it will be safe to ask if this nmethod was unloaded or not. 3536 nm->set_unloading_clock(CompiledMethod::global_unloading_clock()); 3537 } 3538 3539 void clean_nmethod_postponed(CompiledMethod* nm) { 3540 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred); 3541 } 3542 3543 static const int MaxClaimNmethods = 16; 3544 3545 void claim_nmethods(CompiledMethod** claimed_nmethods, int *num_claimed_nmethods) { 3546 CompiledMethod* first; 3547 CompiledMethodIterator last; 3548 3549 do { 3550 *num_claimed_nmethods = 0; 3551 3552 first = _claimed_nmethod; 3553 last = CompiledMethodIterator(first); 3554 3555 if (first != NULL) { 3556 3557 for (int i = 0; i < MaxClaimNmethods; i++) { 3558 if (!last.next_alive()) { 3559 break; 3560 } 3561 claimed_nmethods[i] = last.method(); 3562 (*num_claimed_nmethods)++; 3563 } 3564 } 3565 3566 } while (Atomic::cmpxchg(last.method(), &_claimed_nmethod, first) != first); 3567 } 3568 3569 CompiledMethod* claim_postponed_nmethod() { 3570 CompiledMethod* claim; 3571 CompiledMethod* next; 3572 3573 do { 3574 claim = _postponed_list; 3575 if (claim == NULL) { 3576 return NULL; 3577 } 3578 3579 next = claim->unloading_next(); 3580 3581 } while (Atomic::cmpxchg(next, &_postponed_list, claim) != claim); 3582 3583 return claim; 3584 } 3585 3586 public: 3587 // Mark that we're done with the first pass of nmethod cleaning. 3588 void barrier_mark(uint worker_id) { 3589 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 3590 _num_entered_barrier++; 3591 if (_num_entered_barrier == _num_workers) { 3592 ml.notify_all(); 3593 } 3594 } 3595 3596 // See if we have to wait for the other workers to 3597 // finish their first-pass nmethod cleaning work. 3598 void barrier_wait(uint worker_id) { 3599 if (_num_entered_barrier < _num_workers) { 3600 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 3601 while (_num_entered_barrier < _num_workers) { 3602 ml.wait(Mutex::_no_safepoint_check_flag, 0, false); 3603 } 3604 } 3605 } 3606 3607 // Cleaning and unloading of nmethods. Some work has to be postponed 3608 // to the second pass, when we know which nmethods survive. 3609 void work_first_pass(uint worker_id) { 3610 // The first nmethods is claimed by the first worker. 3611 if (worker_id == 0 && _first_nmethod != NULL) { 3612 clean_nmethod(_first_nmethod); 3613 _first_nmethod = NULL; 3614 } 3615 3616 int num_claimed_nmethods; 3617 CompiledMethod* claimed_nmethods[MaxClaimNmethods]; 3618 3619 while (true) { 3620 claim_nmethods(claimed_nmethods, &num_claimed_nmethods); 3621 3622 if (num_claimed_nmethods == 0) { 3623 break; 3624 } 3625 3626 for (int i = 0; i < num_claimed_nmethods; i++) { 3627 clean_nmethod(claimed_nmethods[i]); 3628 } 3629 } 3630 } 3631 3632 void work_second_pass(uint worker_id) { 3633 CompiledMethod* nm; 3634 // Take care of postponed nmethods. 3635 while ((nm = claim_postponed_nmethod()) != NULL) { 3636 clean_nmethod_postponed(nm); 3637 } 3638 } 3639 }; 3640 3641 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never); 3642 3643 class G1KlassCleaningTask : public StackObj { 3644 BoolObjectClosure* _is_alive; 3645 volatile int _clean_klass_tree_claimed; 3646 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator; 3647 3648 public: 3649 G1KlassCleaningTask(BoolObjectClosure* is_alive) : 3650 _is_alive(is_alive), 3651 _clean_klass_tree_claimed(0), 3652 _klass_iterator() { 3653 } 3654 3655 private: 3656 bool claim_clean_klass_tree_task() { 3657 if (_clean_klass_tree_claimed) { 3658 return false; 3659 } 3660 3661 return Atomic::cmpxchg(1, &_clean_klass_tree_claimed, 0) == 0; 3662 } 3663 3664 InstanceKlass* claim_next_klass() { 3665 Klass* klass; 3666 do { 3667 klass =_klass_iterator.next_klass(); 3668 } while (klass != NULL && !klass->is_instance_klass()); 3669 3670 // this can be null so don't call InstanceKlass::cast 3671 return static_cast<InstanceKlass*>(klass); 3672 } 3673 3674 public: 3675 3676 void clean_klass(InstanceKlass* ik) { 3677 ik->clean_weak_instanceklass_links(_is_alive); 3678 } 3679 3680 void work() { 3681 ResourceMark rm; 3682 3683 // One worker will clean the subklass/sibling klass tree. 3684 if (claim_clean_klass_tree_task()) { 3685 Klass::clean_subklass_tree(_is_alive); 3686 } 3687 3688 // All workers will help cleaning the classes, 3689 InstanceKlass* klass; 3690 while ((klass = claim_next_klass()) != NULL) { 3691 clean_klass(klass); 3692 } 3693 } 3694 }; 3695 3696 class G1ResolvedMethodCleaningTask : public StackObj { 3697 BoolObjectClosure* _is_alive; 3698 volatile int _resolved_method_task_claimed; 3699 public: 3700 G1ResolvedMethodCleaningTask(BoolObjectClosure* is_alive) : 3701 _is_alive(is_alive), _resolved_method_task_claimed(0) {} 3702 3703 bool claim_resolved_method_task() { 3704 if (_resolved_method_task_claimed) { 3705 return false; 3706 } 3707 return Atomic::cmpxchg(1, &_resolved_method_task_claimed, 0) == 0; 3708 } 3709 3710 // These aren't big, one thread can do it all. 3711 void work() { 3712 if (claim_resolved_method_task()) { 3713 ResolvedMethodTable::unlink(_is_alive); 3714 } 3715 } 3716 }; 3717 3718 3719 // To minimize the remark pause times, the tasks below are done in parallel. 3720 class G1ParallelCleaningTask : public AbstractGangTask { 3721 private: 3722 G1StringAndSymbolCleaningTask _string_symbol_task; 3723 G1CodeCacheUnloadingTask _code_cache_task; 3724 G1KlassCleaningTask _klass_cleaning_task; 3725 G1ResolvedMethodCleaningTask _resolved_method_cleaning_task; 3726 3727 public: 3728 // The constructor is run in the VMThread. 3729 G1ParallelCleaningTask(BoolObjectClosure* is_alive, uint num_workers, bool unloading_occurred) : 3730 AbstractGangTask("Parallel Cleaning"), 3731 _string_symbol_task(is_alive, true, true, G1StringDedup::is_enabled()), 3732 _code_cache_task(num_workers, is_alive, unloading_occurred), 3733 _klass_cleaning_task(is_alive), 3734 _resolved_method_cleaning_task(is_alive) { 3735 } 3736 3737 // The parallel work done by all worker threads. 3738 void work(uint worker_id) { 3739 // Do first pass of code cache cleaning. 3740 _code_cache_task.work_first_pass(worker_id); 3741 3742 // Let the threads mark that the first pass is done. 3743 _code_cache_task.barrier_mark(worker_id); 3744 3745 // Clean the Strings and Symbols. 3746 _string_symbol_task.work(worker_id); 3747 3748 // Clean unreferenced things in the ResolvedMethodTable 3749 _resolved_method_cleaning_task.work(); 3750 3751 // Wait for all workers to finish the first code cache cleaning pass. 3752 _code_cache_task.barrier_wait(worker_id); 3753 3754 // Do the second code cache cleaning work, which realize on 3755 // the liveness information gathered during the first pass. 3756 _code_cache_task.work_second_pass(worker_id); 3757 3758 // Clean all klasses that were not unloaded. 3759 _klass_cleaning_task.work(); 3760 } 3761 }; 3762 3763 3764 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive, 3765 bool class_unloading_occurred) { 3766 uint n_workers = workers()->active_workers(); 3767 3768 G1ParallelCleaningTask g1_unlink_task(is_alive, n_workers, class_unloading_occurred); 3769 workers()->run_task(&g1_unlink_task); 3770 } 3771 3772 void G1CollectedHeap::partial_cleaning(BoolObjectClosure* is_alive, 3773 bool process_strings, 3774 bool process_symbols, 3775 bool process_string_dedup) { 3776 if (!process_strings && !process_symbols && !process_string_dedup) { 3777 // Nothing to clean. 3778 return; 3779 } 3780 3781 G1StringAndSymbolCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, process_string_dedup); 3782 workers()->run_task(&g1_unlink_task); 3783 3784 } 3785 3786 class G1RedirtyLoggedCardsTask : public AbstractGangTask { 3787 private: 3788 DirtyCardQueueSet* _queue; 3789 G1CollectedHeap* _g1h; 3790 public: 3791 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"), 3792 _queue(queue), _g1h(g1h) { } 3793 3794 virtual void work(uint worker_id) { 3795 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times(); 3796 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id); 3797 3798 RedirtyLoggedCardTableEntryClosure cl(_g1h); 3799 _queue->par_apply_closure_to_all_completed_buffers(&cl); 3800 3801 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied()); 3802 } 3803 }; 3804 3805 void G1CollectedHeap::redirty_logged_cards() { 3806 double redirty_logged_cards_start = os::elapsedTime(); 3807 3808 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this); 3809 dirty_card_queue_set().reset_for_par_iteration(); 3810 workers()->run_task(&redirty_task); 3811 3812 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set(); 3813 dcq.merge_bufferlists(&dirty_card_queue_set()); 3814 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed"); 3815 3816 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0); 3817 } 3818 3819 // Weak Reference Processing support 3820 3821 // An always "is_alive" closure that is used to preserve referents. 3822 // If the object is non-null then it's alive. Used in the preservation 3823 // of referent objects that are pointed to by reference objects 3824 // discovered by the CM ref processor. 3825 class G1AlwaysAliveClosure: public BoolObjectClosure { 3826 G1CollectedHeap* _g1; 3827 public: 3828 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 3829 bool do_object_b(oop p) { 3830 if (p != NULL) { 3831 return true; 3832 } 3833 return false; 3834 } 3835 }; 3836 3837 bool G1STWIsAliveClosure::do_object_b(oop p) { 3838 // An object is reachable if it is outside the collection set, 3839 // or is inside and copied. 3840 return !_g1->is_in_cset(p) || p->is_forwarded(); 3841 } 3842 3843 // Non Copying Keep Alive closure 3844 class G1KeepAliveClosure: public OopClosure { 3845 G1CollectedHeap* _g1; 3846 public: 3847 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 3848 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } 3849 void do_oop(oop* p) { 3850 oop obj = *p; 3851 assert(obj != NULL, "the caller should have filtered out NULL values"); 3852 3853 const InCSetState cset_state = _g1->in_cset_state(obj); 3854 if (!cset_state.is_in_cset_or_humongous()) { 3855 return; 3856 } 3857 if (cset_state.is_in_cset()) { 3858 assert( obj->is_forwarded(), "invariant" ); 3859 *p = obj->forwardee(); 3860 } else { 3861 assert(!obj->is_forwarded(), "invariant" ); 3862 assert(cset_state.is_humongous(), 3863 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value()); 3864 _g1->set_humongous_is_live(obj); 3865 } 3866 } 3867 }; 3868 3869 // Copying Keep Alive closure - can be called from both 3870 // serial and parallel code as long as different worker 3871 // threads utilize different G1ParScanThreadState instances 3872 // and different queues. 3873 3874 class G1CopyingKeepAliveClosure: public OopClosure { 3875 G1CollectedHeap* _g1h; 3876 OopClosure* _copy_non_heap_obj_cl; 3877 G1ParScanThreadState* _par_scan_state; 3878 3879 public: 3880 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, 3881 OopClosure* non_heap_obj_cl, 3882 G1ParScanThreadState* pss): 3883 _g1h(g1h), 3884 _copy_non_heap_obj_cl(non_heap_obj_cl), 3885 _par_scan_state(pss) 3886 {} 3887 3888 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 3889 virtual void do_oop( oop* p) { do_oop_work(p); } 3890 3891 template <class T> void do_oop_work(T* p) { 3892 oop obj = oopDesc::load_decode_heap_oop(p); 3893 3894 if (_g1h->is_in_cset_or_humongous(obj)) { 3895 // If the referent object has been forwarded (either copied 3896 // to a new location or to itself in the event of an 3897 // evacuation failure) then we need to update the reference 3898 // field and, if both reference and referent are in the G1 3899 // heap, update the RSet for the referent. 3900 // 3901 // If the referent has not been forwarded then we have to keep 3902 // it alive by policy. Therefore we have copy the referent. 3903 // 3904 // If the reference field is in the G1 heap then we can push 3905 // on the PSS queue. When the queue is drained (after each 3906 // phase of reference processing) the object and it's followers 3907 // will be copied, the reference field set to point to the 3908 // new location, and the RSet updated. Otherwise we need to 3909 // use the the non-heap or metadata closures directly to copy 3910 // the referent object and update the pointer, while avoiding 3911 // updating the RSet. 3912 3913 if (_g1h->is_in_g1_reserved(p)) { 3914 _par_scan_state->push_on_queue(p); 3915 } else { 3916 assert(!Metaspace::contains((const void*)p), 3917 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p)); 3918 _copy_non_heap_obj_cl->do_oop(p); 3919 } 3920 } 3921 } 3922 }; 3923 3924 // Serial drain queue closure. Called as the 'complete_gc' 3925 // closure for each discovered list in some of the 3926 // reference processing phases. 3927 3928 class G1STWDrainQueueClosure: public VoidClosure { 3929 protected: 3930 G1CollectedHeap* _g1h; 3931 G1ParScanThreadState* _par_scan_state; 3932 3933 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 3934 3935 public: 3936 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : 3937 _g1h(g1h), 3938 _par_scan_state(pss) 3939 { } 3940 3941 void do_void() { 3942 G1ParScanThreadState* const pss = par_scan_state(); 3943 pss->trim_queue(); 3944 } 3945 }; 3946 3947 // Parallel Reference Processing closures 3948 3949 // Implementation of AbstractRefProcTaskExecutor for parallel reference 3950 // processing during G1 evacuation pauses. 3951 3952 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 3953 private: 3954 G1CollectedHeap* _g1h; 3955 G1ParScanThreadStateSet* _pss; 3956 RefToScanQueueSet* _queues; 3957 WorkGang* _workers; 3958 uint _active_workers; 3959 3960 public: 3961 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, 3962 G1ParScanThreadStateSet* per_thread_states, 3963 WorkGang* workers, 3964 RefToScanQueueSet *task_queues, 3965 uint n_workers) : 3966 _g1h(g1h), 3967 _pss(per_thread_states), 3968 _queues(task_queues), 3969 _workers(workers), 3970 _active_workers(n_workers) 3971 { 3972 g1h->ref_processor_stw()->set_active_mt_degree(n_workers); 3973 } 3974 3975 // Executes the given task using concurrent marking worker threads. 3976 virtual void execute(ProcessTask& task); 3977 virtual void execute(EnqueueTask& task); 3978 }; 3979 3980 // Gang task for possibly parallel reference processing 3981 3982 class G1STWRefProcTaskProxy: public AbstractGangTask { 3983 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 3984 ProcessTask& _proc_task; 3985 G1CollectedHeap* _g1h; 3986 G1ParScanThreadStateSet* _pss; 3987 RefToScanQueueSet* _task_queues; 3988 ParallelTaskTerminator* _terminator; 3989 3990 public: 3991 G1STWRefProcTaskProxy(ProcessTask& proc_task, 3992 G1CollectedHeap* g1h, 3993 G1ParScanThreadStateSet* per_thread_states, 3994 RefToScanQueueSet *task_queues, 3995 ParallelTaskTerminator* terminator) : 3996 AbstractGangTask("Process reference objects in parallel"), 3997 _proc_task(proc_task), 3998 _g1h(g1h), 3999 _pss(per_thread_states), 4000 _task_queues(task_queues), 4001 _terminator(terminator) 4002 {} 4003 4004 virtual void work(uint worker_id) { 4005 // The reference processing task executed by a single worker. 4006 ResourceMark rm; 4007 HandleMark hm; 4008 4009 G1STWIsAliveClosure is_alive(_g1h); 4010 4011 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 4012 pss->set_ref_processor(NULL); 4013 4014 // Keep alive closure. 4015 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss); 4016 4017 // Complete GC closure 4018 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator); 4019 4020 // Call the reference processing task's work routine. 4021 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); 4022 4023 // Note we cannot assert that the refs array is empty here as not all 4024 // of the processing tasks (specifically phase2 - pp2_work) execute 4025 // the complete_gc closure (which ordinarily would drain the queue) so 4026 // the queue may not be empty. 4027 } 4028 }; 4029 4030 // Driver routine for parallel reference processing. 4031 // Creates an instance of the ref processing gang 4032 // task and has the worker threads execute it. 4033 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) { 4034 assert(_workers != NULL, "Need parallel worker threads."); 4035 4036 ParallelTaskTerminator terminator(_active_workers, _queues); 4037 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator); 4038 4039 _workers->run_task(&proc_task_proxy); 4040 } 4041 4042 // Gang task for parallel reference enqueueing. 4043 4044 class G1STWRefEnqueueTaskProxy: public AbstractGangTask { 4045 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; 4046 EnqueueTask& _enq_task; 4047 4048 public: 4049 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) : 4050 AbstractGangTask("Enqueue reference objects in parallel"), 4051 _enq_task(enq_task) 4052 { } 4053 4054 virtual void work(uint worker_id) { 4055 _enq_task.work(worker_id); 4056 } 4057 }; 4058 4059 // Driver routine for parallel reference enqueueing. 4060 // Creates an instance of the ref enqueueing gang 4061 // task and has the worker threads execute it. 4062 4063 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) { 4064 assert(_workers != NULL, "Need parallel worker threads."); 4065 4066 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task); 4067 4068 _workers->run_task(&enq_task_proxy); 4069 } 4070 4071 // End of weak reference support closures 4072 4073 // Abstract task used to preserve (i.e. copy) any referent objects 4074 // that are in the collection set and are pointed to by reference 4075 // objects discovered by the CM ref processor. 4076 4077 class G1ParPreserveCMReferentsTask: public AbstractGangTask { 4078 protected: 4079 G1CollectedHeap* _g1h; 4080 G1ParScanThreadStateSet* _pss; 4081 RefToScanQueueSet* _queues; 4082 ParallelTaskTerminator _terminator; 4083 uint _n_workers; 4084 4085 public: 4086 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) : 4087 AbstractGangTask("ParPreserveCMReferents"), 4088 _g1h(g1h), 4089 _pss(per_thread_states), 4090 _queues(task_queues), 4091 _terminator(workers, _queues), 4092 _n_workers(workers) 4093 { 4094 g1h->ref_processor_cm()->set_active_mt_degree(workers); 4095 } 4096 4097 void work(uint worker_id) { 4098 G1GCParPhaseTimesTracker x(_g1h->g1_policy()->phase_times(), G1GCPhaseTimes::PreserveCMReferents, worker_id); 4099 4100 ResourceMark rm; 4101 HandleMark hm; 4102 4103 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 4104 pss->set_ref_processor(NULL); 4105 assert(pss->queue_is_empty(), "both queue and overflow should be empty"); 4106 4107 // Is alive closure 4108 G1AlwaysAliveClosure always_alive(_g1h); 4109 4110 // Copying keep alive closure. Applied to referent objects that need 4111 // to be copied. 4112 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss); 4113 4114 ReferenceProcessor* rp = _g1h->ref_processor_cm(); 4115 4116 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q(); 4117 uint stride = MIN2(MAX2(_n_workers, 1U), limit); 4118 4119 // limit is set using max_num_q() - which was set using ParallelGCThreads. 4120 // So this must be true - but assert just in case someone decides to 4121 // change the worker ids. 4122 assert(worker_id < limit, "sanity"); 4123 assert(!rp->discovery_is_atomic(), "check this code"); 4124 4125 // Select discovered lists [i, i+stride, i+2*stride,...,limit) 4126 for (uint idx = worker_id; idx < limit; idx += stride) { 4127 DiscoveredList& ref_list = rp->discovered_refs()[idx]; 4128 4129 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive); 4130 while (iter.has_next()) { 4131 // Since discovery is not atomic for the CM ref processor, we 4132 // can see some null referent objects. 4133 iter.load_ptrs(DEBUG_ONLY(true)); 4134 oop ref = iter.obj(); 4135 4136 // This will filter nulls. 4137 if (iter.is_referent_alive()) { 4138 iter.make_referent_alive(); 4139 } 4140 iter.move_to_next(); 4141 } 4142 } 4143 4144 // Drain the queue - which may cause stealing 4145 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator); 4146 drain_queue.do_void(); 4147 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure 4148 assert(pss->queue_is_empty(), "should be"); 4149 } 4150 }; 4151 4152 void G1CollectedHeap::preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states) { 4153 // Any reference objects, in the collection set, that were 'discovered' 4154 // by the CM ref processor should have already been copied (either by 4155 // applying the external root copy closure to the discovered lists, or 4156 // by following an RSet entry). 4157 // 4158 // But some of the referents, that are in the collection set, that these 4159 // reference objects point to may not have been copied: the STW ref 4160 // processor would have seen that the reference object had already 4161 // been 'discovered' and would have skipped discovering the reference, 4162 // but would not have treated the reference object as a regular oop. 4163 // As a result the copy closure would not have been applied to the 4164 // referent object. 4165 // 4166 // We need to explicitly copy these referent objects - the references 4167 // will be processed at the end of remarking. 4168 // 4169 // We also need to do this copying before we process the reference 4170 // objects discovered by the STW ref processor in case one of these 4171 // referents points to another object which is also referenced by an 4172 // object discovered by the STW ref processor. 4173 double preserve_cm_referents_time = 0.0; 4174 4175 // To avoid spawning task when there is no work to do, check that 4176 // a concurrent cycle is active and that some references have been 4177 // discovered. 4178 if (concurrent_mark()->cm_thread()->during_cycle() && 4179 ref_processor_cm()->has_discovered_references()) { 4180 double preserve_cm_referents_start = os::elapsedTime(); 4181 uint no_of_gc_workers = workers()->active_workers(); 4182 G1ParPreserveCMReferentsTask keep_cm_referents(this, 4183 per_thread_states, 4184 no_of_gc_workers, 4185 _task_queues); 4186 workers()->run_task(&keep_cm_referents); 4187 preserve_cm_referents_time = os::elapsedTime() - preserve_cm_referents_start; 4188 } 4189 4190 g1_policy()->phase_times()->record_preserve_cm_referents_time_ms(preserve_cm_referents_time * 1000.0); 4191 } 4192 4193 // Weak Reference processing during an evacuation pause (part 1). 4194 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) { 4195 double ref_proc_start = os::elapsedTime(); 4196 4197 ReferenceProcessor* rp = _ref_processor_stw; 4198 assert(rp->discovery_enabled(), "should have been enabled"); 4199 4200 // Closure to test whether a referent is alive. 4201 G1STWIsAliveClosure is_alive(this); 4202 4203 // Even when parallel reference processing is enabled, the processing 4204 // of JNI refs is serial and performed serially by the current thread 4205 // rather than by a worker. The following PSS will be used for processing 4206 // JNI refs. 4207 4208 // Use only a single queue for this PSS. 4209 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0); 4210 pss->set_ref_processor(NULL); 4211 assert(pss->queue_is_empty(), "pre-condition"); 4212 4213 // Keep alive closure. 4214 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss); 4215 4216 // Serial Complete GC closure 4217 G1STWDrainQueueClosure drain_queue(this, pss); 4218 4219 // Setup the soft refs policy... 4220 rp->setup_policy(false); 4221 4222 ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times(); 4223 4224 ReferenceProcessorStats stats; 4225 if (!rp->processing_is_mt()) { 4226 // Serial reference processing... 4227 stats = rp->process_discovered_references(&is_alive, 4228 &keep_alive, 4229 &drain_queue, 4230 NULL, 4231 pt); 4232 } else { 4233 uint no_of_gc_workers = workers()->active_workers(); 4234 4235 // Parallel reference processing 4236 assert(no_of_gc_workers <= rp->max_num_q(), 4237 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u", 4238 no_of_gc_workers, rp->max_num_q()); 4239 4240 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers); 4241 stats = rp->process_discovered_references(&is_alive, 4242 &keep_alive, 4243 &drain_queue, 4244 &par_task_executor, 4245 pt); 4246 } 4247 4248 _gc_tracer_stw->report_gc_reference_stats(stats); 4249 4250 // We have completed copying any necessary live referent objects. 4251 assert(pss->queue_is_empty(), "both queue and overflow should be empty"); 4252 4253 double ref_proc_time = os::elapsedTime() - ref_proc_start; 4254 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 4255 } 4256 4257 // Weak Reference processing during an evacuation pause (part 2). 4258 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) { 4259 double ref_enq_start = os::elapsedTime(); 4260 4261 ReferenceProcessor* rp = _ref_processor_stw; 4262 assert(!rp->discovery_enabled(), "should have been disabled as part of processing"); 4263 4264 ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times(); 4265 4266 // Now enqueue any remaining on the discovered lists on to 4267 // the pending list. 4268 if (!rp->processing_is_mt()) { 4269 // Serial reference processing... 4270 rp->enqueue_discovered_references(NULL, pt); 4271 } else { 4272 // Parallel reference enqueueing 4273 4274 uint n_workers = workers()->active_workers(); 4275 4276 assert(n_workers <= rp->max_num_q(), 4277 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u", 4278 n_workers, rp->max_num_q()); 4279 4280 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers); 4281 rp->enqueue_discovered_references(&par_task_executor, pt); 4282 } 4283 4284 rp->verify_no_references_recorded(); 4285 assert(!rp->discovery_enabled(), "should have been disabled"); 4286 4287 // If during an initial mark pause we install a pending list head which is not otherwise reachable 4288 // ensure that it is marked in the bitmap for concurrent marking to discover. 4289 if (collector_state()->during_initial_mark_pause()) { 4290 oop pll_head = Universe::reference_pending_list(); 4291 if (pll_head != NULL) { 4292 _cm->mark_in_next_bitmap(pll_head); 4293 } 4294 } 4295 4296 // FIXME 4297 // CM's reference processing also cleans up the string and symbol tables. 4298 // Should we do that here also? We could, but it is a serial operation 4299 // and could significantly increase the pause time. 4300 4301 double ref_enq_time = os::elapsedTime() - ref_enq_start; 4302 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0); 4303 } 4304 4305 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) { 4306 double merge_pss_time_start = os::elapsedTime(); 4307 per_thread_states->flush(); 4308 g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0); 4309 } 4310 4311 void G1CollectedHeap::pre_evacuate_collection_set() { 4312 _expand_heap_after_alloc_failure = true; 4313 _evacuation_failed = false; 4314 4315 // Disable the hot card cache. 4316 _hot_card_cache->reset_hot_cache_claimed_index(); 4317 _hot_card_cache->set_use_cache(false); 4318 4319 g1_rem_set()->prepare_for_oops_into_collection_set_do(); 4320 _preserved_marks_set.assert_empty(); 4321 4322 G1GCPhaseTimes* phase_times = g1_policy()->phase_times(); 4323 4324 // InitialMark needs claim bits to keep track of the marked-through CLDs. 4325 if (collector_state()->during_initial_mark_pause()) { 4326 double start_clear_claimed_marks = os::elapsedTime(); 4327 4328 ClassLoaderDataGraph::clear_claimed_marks(); 4329 4330 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0; 4331 phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms); 4332 } 4333 } 4334 4335 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) { 4336 // Should G1EvacuationFailureALot be in effect for this GC? 4337 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) 4338 4339 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty"); 4340 4341 G1GCPhaseTimes* phase_times = g1_policy()->phase_times(); 4342 4343 double start_par_time_sec = os::elapsedTime(); 4344 double end_par_time_sec; 4345 4346 { 4347 const uint n_workers = workers()->active_workers(); 4348 G1RootProcessor root_processor(this, n_workers); 4349 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers); 4350 4351 print_termination_stats_hdr(); 4352 4353 workers()->run_task(&g1_par_task); 4354 end_par_time_sec = os::elapsedTime(); 4355 4356 // Closing the inner scope will execute the destructor 4357 // for the G1RootProcessor object. We record the current 4358 // elapsed time before closing the scope so that time 4359 // taken for the destructor is NOT included in the 4360 // reported parallel time. 4361 } 4362 4363 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0; 4364 phase_times->record_par_time(par_time_ms); 4365 4366 double code_root_fixup_time_ms = 4367 (os::elapsedTime() - end_par_time_sec) * 1000.0; 4368 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms); 4369 } 4370 4371 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) { 4372 // Process any discovered reference objects - we have 4373 // to do this _before_ we retire the GC alloc regions 4374 // as we may have to copy some 'reachable' referent 4375 // objects (and their reachable sub-graphs) that were 4376 // not copied during the pause. 4377 if (g1_policy()->should_process_references()) { 4378 preserve_cm_referents(per_thread_states); 4379 process_discovered_references(per_thread_states); 4380 } else { 4381 ref_processor_stw()->verify_no_references_recorded(); 4382 } 4383 4384 G1STWIsAliveClosure is_alive(this); 4385 G1KeepAliveClosure keep_alive(this); 4386 4387 { 4388 double start = os::elapsedTime(); 4389 4390 WeakProcessor::weak_oops_do(&is_alive, &keep_alive); 4391 4392 double time_ms = (os::elapsedTime() - start) * 1000.0; 4393 g1_policy()->phase_times()->record_ref_proc_time(time_ms); 4394 } 4395 4396 if (G1StringDedup::is_enabled()) { 4397 double fixup_start = os::elapsedTime(); 4398 4399 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times()); 4400 4401 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0; 4402 g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms); 4403 } 4404 4405 g1_rem_set()->cleanup_after_oops_into_collection_set_do(); 4406 4407 if (evacuation_failed()) { 4408 restore_after_evac_failure(); 4409 4410 // Reset the G1EvacuationFailureALot counters and flags 4411 // Note: the values are reset only when an actual 4412 // evacuation failure occurs. 4413 NOT_PRODUCT(reset_evacuation_should_fail();) 4414 } 4415 4416 _preserved_marks_set.assert_empty(); 4417 4418 // Enqueue any remaining references remaining on the STW 4419 // reference processor's discovered lists. We need to do 4420 // this after the card table is cleaned (and verified) as 4421 // the act of enqueueing entries on to the pending list 4422 // will log these updates (and dirty their associated 4423 // cards). We need these updates logged to update any 4424 // RSets. 4425 if (g1_policy()->should_process_references()) { 4426 enqueue_discovered_references(per_thread_states); 4427 } else { 4428 g1_policy()->phase_times()->record_ref_enq_time(0); 4429 } 4430 4431 _allocator->release_gc_alloc_regions(evacuation_info); 4432 4433 merge_per_thread_state_info(per_thread_states); 4434 4435 // Reset and re-enable the hot card cache. 4436 // Note the counts for the cards in the regions in the 4437 // collection set are reset when the collection set is freed. 4438 _hot_card_cache->reset_hot_cache(); 4439 _hot_card_cache->set_use_cache(true); 4440 4441 purge_code_root_memory(); 4442 4443 redirty_logged_cards(); 4444 #if COMPILER2_OR_JVMCI 4445 double start = os::elapsedTime(); 4446 DerivedPointerTable::update_pointers(); 4447 g1_policy()->phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0); 4448 #endif 4449 g1_policy()->print_age_table(); 4450 } 4451 4452 void G1CollectedHeap::record_obj_copy_mem_stats() { 4453 g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize); 4454 4455 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats), 4456 create_g1_evac_summary(&_old_evac_stats)); 4457 } 4458 4459 void G1CollectedHeap::free_region(HeapRegion* hr, 4460 FreeRegionList* free_list, 4461 bool skip_remset, 4462 bool skip_hot_card_cache, 4463 bool locked) { 4464 assert(!hr->is_free(), "the region should not be free"); 4465 assert(!hr->is_empty(), "the region should not be empty"); 4466 assert(_hrm.is_available(hr->hrm_index()), "region should be committed"); 4467 assert(free_list != NULL, "pre-condition"); 4468 4469 if (G1VerifyBitmaps) { 4470 MemRegion mr(hr->bottom(), hr->end()); 4471 concurrent_mark()->clear_range_in_prev_bitmap(mr); 4472 } 4473 4474 // Clear the card counts for this region. 4475 // Note: we only need to do this if the region is not young 4476 // (since we don't refine cards in young regions). 4477 if (!skip_hot_card_cache && !hr->is_young()) { 4478 _hot_card_cache->reset_card_counts(hr); 4479 } 4480 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */); 4481 free_list->add_ordered(hr); 4482 } 4483 4484 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 4485 FreeRegionList* free_list, 4486 bool skip_remset) { 4487 assert(hr->is_humongous(), "this is only for humongous regions"); 4488 assert(free_list != NULL, "pre-condition"); 4489 hr->clear_humongous(); 4490 free_region(hr, free_list, skip_remset); 4491 } 4492 4493 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed, 4494 const uint humongous_regions_removed) { 4495 if (old_regions_removed > 0 || humongous_regions_removed > 0) { 4496 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 4497 _old_set.bulk_remove(old_regions_removed); 4498 _humongous_set.bulk_remove(humongous_regions_removed); 4499 } 4500 4501 } 4502 4503 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) { 4504 assert(list != NULL, "list can't be null"); 4505 if (!list->is_empty()) { 4506 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag); 4507 _hrm.insert_list_into_free_list(list); 4508 } 4509 } 4510 4511 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) { 4512 decrease_used(bytes); 4513 } 4514 4515 class G1ParScrubRemSetTask: public AbstractGangTask { 4516 protected: 4517 G1RemSet* _g1rs; 4518 HeapRegionClaimer _hrclaimer; 4519 4520 public: 4521 G1ParScrubRemSetTask(G1RemSet* g1_rs, uint num_workers) : 4522 AbstractGangTask("G1 ScrubRS"), 4523 _g1rs(g1_rs), 4524 _hrclaimer(num_workers) { 4525 } 4526 4527 void work(uint worker_id) { 4528 _g1rs->scrub(worker_id, &_hrclaimer); 4529 } 4530 }; 4531 4532 void G1CollectedHeap::scrub_rem_set() { 4533 uint num_workers = workers()->active_workers(); 4534 G1ParScrubRemSetTask g1_par_scrub_rs_task(g1_rem_set(), num_workers); 4535 workers()->run_task(&g1_par_scrub_rs_task); 4536 } 4537 4538 class G1FreeCollectionSetTask : public AbstractGangTask { 4539 private: 4540 4541 // Closure applied to all regions in the collection set to do work that needs to 4542 // be done serially in a single thread. 4543 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure { 4544 private: 4545 EvacuationInfo* _evacuation_info; 4546 const size_t* _surviving_young_words; 4547 4548 // Bytes used in successfully evacuated regions before the evacuation. 4549 size_t _before_used_bytes; 4550 // Bytes used in unsucessfully evacuated regions before the evacuation 4551 size_t _after_used_bytes; 4552 4553 size_t _bytes_allocated_in_old_since_last_gc; 4554 4555 size_t _failure_used_words; 4556 size_t _failure_waste_words; 4557 4558 FreeRegionList _local_free_list; 4559 public: 4560 G1SerialFreeCollectionSetClosure(EvacuationInfo* evacuation_info, const size_t* surviving_young_words) : 4561 HeapRegionClosure(), 4562 _evacuation_info(evacuation_info), 4563 _surviving_young_words(surviving_young_words), 4564 _before_used_bytes(0), 4565 _after_used_bytes(0), 4566 _bytes_allocated_in_old_since_last_gc(0), 4567 _failure_used_words(0), 4568 _failure_waste_words(0), 4569 _local_free_list("Local Region List for CSet Freeing") { 4570 } 4571 4572 virtual bool doHeapRegion(HeapRegion* r) { 4573 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4574 4575 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index()); 4576 g1h->clear_in_cset(r); 4577 4578 if (r->is_young()) { 4579 assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(), 4580 "Young index %d is wrong for region %u of type %s with %u young regions", 4581 r->young_index_in_cset(), 4582 r->hrm_index(), 4583 r->get_type_str(), 4584 g1h->collection_set()->young_region_length()); 4585 size_t words_survived = _surviving_young_words[r->young_index_in_cset()]; 4586 r->record_surv_words_in_group(words_survived); 4587 } 4588 4589 if (!r->evacuation_failed()) { 4590 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index()); 4591 _before_used_bytes += r->used(); 4592 g1h->free_region(r, 4593 &_local_free_list, 4594 true, /* skip_remset */ 4595 true, /* skip_hot_card_cache */ 4596 true /* locked */); 4597 } else { 4598 r->uninstall_surv_rate_group(); 4599 r->set_young_index_in_cset(-1); 4600 r->set_evacuation_failed(false); 4601 // When moving a young gen region to old gen, we "allocate" that whole region 4602 // there. This is in addition to any already evacuated objects. Notify the 4603 // policy about that. 4604 // Old gen regions do not cause an additional allocation: both the objects 4605 // still in the region and the ones already moved are accounted for elsewhere. 4606 if (r->is_young()) { 4607 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes; 4608 } 4609 // The region is now considered to be old. 4610 r->set_old(); 4611 // Do some allocation statistics accounting. Regions that failed evacuation 4612 // are always made old, so there is no need to update anything in the young 4613 // gen statistics, but we need to update old gen statistics. 4614 size_t used_words = r->marked_bytes() / HeapWordSize; 4615 4616 _failure_used_words += used_words; 4617 _failure_waste_words += HeapRegion::GrainWords - used_words; 4618 4619 g1h->old_set_add(r); 4620 _after_used_bytes += r->used(); 4621 } 4622 return false; 4623 } 4624 4625 void complete_work() { 4626 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4627 4628 _evacuation_info->set_regions_freed(_local_free_list.length()); 4629 _evacuation_info->increment_collectionset_used_after(_after_used_bytes); 4630 4631 g1h->prepend_to_freelist(&_local_free_list); 4632 g1h->decrement_summary_bytes(_before_used_bytes); 4633 4634 G1Policy* policy = g1h->g1_policy(); 4635 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc); 4636 4637 g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words); 4638 } 4639 }; 4640 4641 G1CollectionSet* _collection_set; 4642 G1SerialFreeCollectionSetClosure _cl; 4643 const size_t* _surviving_young_words; 4644 4645 size_t _rs_lengths; 4646 4647 volatile jint _serial_work_claim; 4648 4649 struct WorkItem { 4650 uint region_idx; 4651 bool is_young; 4652 bool evacuation_failed; 4653 4654 WorkItem(HeapRegion* r) { 4655 region_idx = r->hrm_index(); 4656 is_young = r->is_young(); 4657 evacuation_failed = r->evacuation_failed(); 4658 } 4659 }; 4660 4661 volatile size_t _parallel_work_claim; 4662 size_t _num_work_items; 4663 WorkItem* _work_items; 4664 4665 void do_serial_work() { 4666 // Need to grab the lock to be allowed to modify the old region list. 4667 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 4668 _collection_set->iterate(&_cl); 4669 } 4670 4671 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) { 4672 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4673 4674 HeapRegion* r = g1h->region_at(region_idx); 4675 assert(!g1h->is_on_master_free_list(r), "sanity"); 4676 4677 Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths); 4678 4679 if (!is_young) { 4680 g1h->_hot_card_cache->reset_card_counts(r); 4681 } 4682 4683 if (!evacuation_failed) { 4684 r->rem_set()->clear_locked(); 4685 } 4686 } 4687 4688 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure { 4689 private: 4690 size_t _cur_idx; 4691 WorkItem* _work_items; 4692 public: 4693 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { } 4694 4695 virtual bool doHeapRegion(HeapRegion* r) { 4696 _work_items[_cur_idx++] = WorkItem(r); 4697 return false; 4698 } 4699 }; 4700 4701 void prepare_work() { 4702 G1PrepareFreeCollectionSetClosure cl(_work_items); 4703 _collection_set->iterate(&cl); 4704 } 4705 4706 void complete_work() { 4707 _cl.complete_work(); 4708 4709 G1Policy* policy = G1CollectedHeap::heap()->g1_policy(); 4710 policy->record_max_rs_lengths(_rs_lengths); 4711 policy->cset_regions_freed(); 4712 } 4713 public: 4714 G1FreeCollectionSetTask(G1CollectionSet* collection_set, EvacuationInfo* evacuation_info, const size_t* surviving_young_words) : 4715 AbstractGangTask("G1 Free Collection Set"), 4716 _cl(evacuation_info, surviving_young_words), 4717 _collection_set(collection_set), 4718 _surviving_young_words(surviving_young_words), 4719 _serial_work_claim(0), 4720 _rs_lengths(0), 4721 _parallel_work_claim(0), 4722 _num_work_items(collection_set->region_length()), 4723 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) { 4724 prepare_work(); 4725 } 4726 4727 ~G1FreeCollectionSetTask() { 4728 complete_work(); 4729 FREE_C_HEAP_ARRAY(WorkItem, _work_items); 4730 } 4731 4732 // Chunk size for work distribution. The chosen value has been determined experimentally 4733 // to be a good tradeoff between overhead and achievable parallelism. 4734 static uint chunk_size() { return 32; } 4735 4736 virtual void work(uint worker_id) { 4737 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times(); 4738 4739 // Claim serial work. 4740 if (_serial_work_claim == 0) { 4741 jint value = Atomic::add(1, &_serial_work_claim) - 1; 4742 if (value == 0) { 4743 double serial_time = os::elapsedTime(); 4744 do_serial_work(); 4745 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0); 4746 } 4747 } 4748 4749 // Start parallel work. 4750 double young_time = 0.0; 4751 bool has_young_time = false; 4752 double non_young_time = 0.0; 4753 bool has_non_young_time = false; 4754 4755 while (true) { 4756 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim); 4757 size_t cur = end - chunk_size(); 4758 4759 if (cur >= _num_work_items) { 4760 break; 4761 } 4762 4763 double start_time = os::elapsedTime(); 4764 4765 end = MIN2(end, _num_work_items); 4766 4767 for (; cur < end; cur++) { 4768 bool is_young = _work_items[cur].is_young; 4769 4770 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed); 4771 4772 double end_time = os::elapsedTime(); 4773 double time_taken = end_time - start_time; 4774 if (is_young) { 4775 young_time += time_taken; 4776 has_young_time = true; 4777 } else { 4778 non_young_time += time_taken; 4779 has_non_young_time = true; 4780 } 4781 start_time = end_time; 4782 } 4783 } 4784 4785 if (has_young_time) { 4786 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time); 4787 } 4788 if (has_non_young_time) { 4789 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, young_time); 4790 } 4791 } 4792 }; 4793 4794 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) { 4795 _eden.clear(); 4796 4797 double free_cset_start_time = os::elapsedTime(); 4798 4799 { 4800 uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U); 4801 uint const num_workers = MIN2(workers()->active_workers(), num_chunks); 4802 4803 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words); 4804 4805 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u", 4806 cl.name(), 4807 num_workers, 4808 _collection_set.region_length()); 4809 workers()->run_task(&cl, num_workers); 4810 } 4811 g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0); 4812 4813 collection_set->clear(); 4814 } 4815 4816 class G1FreeHumongousRegionClosure : public HeapRegionClosure { 4817 private: 4818 FreeRegionList* _free_region_list; 4819 HeapRegionSet* _proxy_set; 4820 uint _humongous_objects_reclaimed; 4821 uint _humongous_regions_reclaimed; 4822 size_t _freed_bytes; 4823 public: 4824 4825 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) : 4826 _free_region_list(free_region_list), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) { 4827 } 4828 4829 virtual bool doHeapRegion(HeapRegion* r) { 4830 if (!r->is_starts_humongous()) { 4831 return false; 4832 } 4833 4834 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4835 4836 oop obj = (oop)r->bottom(); 4837 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap(); 4838 4839 // The following checks whether the humongous object is live are sufficient. 4840 // The main additional check (in addition to having a reference from the roots 4841 // or the young gen) is whether the humongous object has a remembered set entry. 4842 // 4843 // A humongous object cannot be live if there is no remembered set for it 4844 // because: 4845 // - there can be no references from within humongous starts regions referencing 4846 // the object because we never allocate other objects into them. 4847 // (I.e. there are no intra-region references that may be missed by the 4848 // remembered set) 4849 // - as soon there is a remembered set entry to the humongous starts region 4850 // (i.e. it has "escaped" to an old object) this remembered set entry will stay 4851 // until the end of a concurrent mark. 4852 // 4853 // It is not required to check whether the object has been found dead by marking 4854 // or not, in fact it would prevent reclamation within a concurrent cycle, as 4855 // all objects allocated during that time are considered live. 4856 // SATB marking is even more conservative than the remembered set. 4857 // So if at this point in the collection there is no remembered set entry, 4858 // nobody has a reference to it. 4859 // At the start of collection we flush all refinement logs, and remembered sets 4860 // are completely up-to-date wrt to references to the humongous object. 4861 // 4862 // Other implementation considerations: 4863 // - never consider object arrays at this time because they would pose 4864 // considerable effort for cleaning up the the remembered sets. This is 4865 // required because stale remembered sets might reference locations that 4866 // are currently allocated into. 4867 uint region_idx = r->hrm_index(); 4868 if (!g1h->is_humongous_reclaim_candidate(region_idx) || 4869 !r->rem_set()->is_empty()) { 4870 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", 4871 region_idx, 4872 (size_t)obj->size() * HeapWordSize, 4873 p2i(r->bottom()), 4874 r->rem_set()->occupied(), 4875 r->rem_set()->strong_code_roots_list_length(), 4876 next_bitmap->is_marked(r->bottom()), 4877 g1h->is_humongous_reclaim_candidate(region_idx), 4878 obj->is_typeArray() 4879 ); 4880 return false; 4881 } 4882 4883 guarantee(obj->is_typeArray(), 4884 "Only eagerly reclaiming type arrays is supported, but the object " 4885 PTR_FORMAT " is not.", p2i(r->bottom())); 4886 4887 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", 4888 region_idx, 4889 (size_t)obj->size() * HeapWordSize, 4890 p2i(r->bottom()), 4891 r->rem_set()->occupied(), 4892 r->rem_set()->strong_code_roots_list_length(), 4893 next_bitmap->is_marked(r->bottom()), 4894 g1h->is_humongous_reclaim_candidate(region_idx), 4895 obj->is_typeArray() 4896 ); 4897 4898 // Need to clear mark bit of the humongous object if already set. 4899 if (next_bitmap->is_marked(r->bottom())) { 4900 next_bitmap->clear(r->bottom()); 4901 } 4902 _humongous_objects_reclaimed++; 4903 do { 4904 HeapRegion* next = g1h->next_region_in_humongous(r); 4905 _freed_bytes += r->used(); 4906 r->set_containing_set(NULL); 4907 _humongous_regions_reclaimed++; 4908 g1h->free_humongous_region(r, _free_region_list, false /* skip_remset */ ); 4909 r = next; 4910 } while (r != NULL); 4911 4912 return false; 4913 } 4914 4915 uint humongous_objects_reclaimed() { 4916 return _humongous_objects_reclaimed; 4917 } 4918 4919 uint humongous_regions_reclaimed() { 4920 return _humongous_regions_reclaimed; 4921 } 4922 4923 size_t bytes_freed() const { 4924 return _freed_bytes; 4925 } 4926 }; 4927 4928 void G1CollectedHeap::eagerly_reclaim_humongous_regions() { 4929 assert_at_safepoint(true); 4930 4931 if (!G1EagerReclaimHumongousObjects || 4932 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) { 4933 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0); 4934 return; 4935 } 4936 4937 double start_time = os::elapsedTime(); 4938 4939 FreeRegionList local_cleanup_list("Local Humongous Cleanup List"); 4940 4941 G1FreeHumongousRegionClosure cl(&local_cleanup_list); 4942 heap_region_iterate(&cl); 4943 4944 remove_from_old_sets(0, cl.humongous_regions_reclaimed()); 4945 4946 G1HRPrinter* hrp = hr_printer(); 4947 if (hrp->is_active()) { 4948 FreeRegionListIterator iter(&local_cleanup_list); 4949 while (iter.more_available()) { 4950 HeapRegion* hr = iter.get_next(); 4951 hrp->cleanup(hr); 4952 } 4953 } 4954 4955 prepend_to_freelist(&local_cleanup_list); 4956 decrement_summary_bytes(cl.bytes_freed()); 4957 4958 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0, 4959 cl.humongous_objects_reclaimed()); 4960 } 4961 4962 class G1AbandonCollectionSetClosure : public HeapRegionClosure { 4963 public: 4964 virtual bool doHeapRegion(HeapRegion* r) { 4965 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index()); 4966 G1CollectedHeap::heap()->clear_in_cset(r); 4967 r->set_young_index_in_cset(-1); 4968 return false; 4969 } 4970 }; 4971 4972 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) { 4973 G1AbandonCollectionSetClosure cl; 4974 collection_set->iterate(&cl); 4975 4976 collection_set->clear(); 4977 collection_set->stop_incremental_building(); 4978 } 4979 4980 void G1CollectedHeap::set_free_regions_coming() { 4981 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : setting free regions coming"); 4982 4983 assert(!free_regions_coming(), "pre-condition"); 4984 _free_regions_coming = true; 4985 } 4986 4987 void G1CollectedHeap::reset_free_regions_coming() { 4988 assert(free_regions_coming(), "pre-condition"); 4989 4990 { 4991 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 4992 _free_regions_coming = false; 4993 SecondaryFreeList_lock->notify_all(); 4994 } 4995 4996 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : reset free regions coming"); 4997 } 4998 4999 void G1CollectedHeap::wait_while_free_regions_coming() { 5000 // Most of the time we won't have to wait, so let's do a quick test 5001 // first before we take the lock. 5002 if (!free_regions_coming()) { 5003 return; 5004 } 5005 5006 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : waiting for free regions"); 5007 5008 { 5009 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 5010 while (free_regions_coming()) { 5011 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 5012 } 5013 } 5014 5015 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : done waiting for free regions"); 5016 } 5017 5018 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) { 5019 return _allocator->is_retained_old_region(hr); 5020 } 5021 5022 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 5023 _eden.add(hr); 5024 _g1_policy->set_region_eden(hr); 5025 } 5026 5027 #ifdef ASSERT 5028 5029 class NoYoungRegionsClosure: public HeapRegionClosure { 5030 private: 5031 bool _success; 5032 public: 5033 NoYoungRegionsClosure() : _success(true) { } 5034 bool doHeapRegion(HeapRegion* r) { 5035 if (r->is_young()) { 5036 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young", 5037 p2i(r->bottom()), p2i(r->end())); 5038 _success = false; 5039 } 5040 return false; 5041 } 5042 bool success() { return _success; } 5043 }; 5044 5045 bool G1CollectedHeap::check_young_list_empty() { 5046 bool ret = (young_regions_count() == 0); 5047 5048 NoYoungRegionsClosure closure; 5049 heap_region_iterate(&closure); 5050 ret = ret && closure.success(); 5051 5052 return ret; 5053 } 5054 5055 #endif // ASSERT 5056 5057 class TearDownRegionSetsClosure : public HeapRegionClosure { 5058 private: 5059 HeapRegionSet *_old_set; 5060 5061 public: 5062 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { } 5063 5064 bool doHeapRegion(HeapRegion* r) { 5065 if (r->is_old()) { 5066 _old_set->remove(r); 5067 } else if(r->is_young()) { 5068 r->uninstall_surv_rate_group(); 5069 } else { 5070 // We ignore free regions, we'll empty the free list afterwards. 5071 // We ignore humongous regions, we're not tearing down the 5072 // humongous regions set. 5073 assert(r->is_free() || r->is_humongous(), 5074 "it cannot be another type"); 5075 } 5076 return false; 5077 } 5078 5079 ~TearDownRegionSetsClosure() { 5080 assert(_old_set->is_empty(), "post-condition"); 5081 } 5082 }; 5083 5084 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) { 5085 assert_at_safepoint(true /* should_be_vm_thread */); 5086 5087 if (!free_list_only) { 5088 TearDownRegionSetsClosure cl(&_old_set); 5089 heap_region_iterate(&cl); 5090 5091 // Note that emptying the _young_list is postponed and instead done as 5092 // the first step when rebuilding the regions sets again. The reason for 5093 // this is that during a full GC string deduplication needs to know if 5094 // a collected region was young or old when the full GC was initiated. 5095 } 5096 _hrm.remove_all_free_regions(); 5097 } 5098 5099 void G1CollectedHeap::increase_used(size_t bytes) { 5100 _summary_bytes_used += bytes; 5101 } 5102 5103 void G1CollectedHeap::decrease_used(size_t bytes) { 5104 assert(_summary_bytes_used >= bytes, 5105 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT, 5106 _summary_bytes_used, bytes); 5107 _summary_bytes_used -= bytes; 5108 } 5109 5110 void G1CollectedHeap::set_used(size_t bytes) { 5111 _summary_bytes_used = bytes; 5112 } 5113 5114 class RebuildRegionSetsClosure : public HeapRegionClosure { 5115 private: 5116 bool _free_list_only; 5117 HeapRegionSet* _old_set; 5118 HeapRegionManager* _hrm; 5119 size_t _total_used; 5120 5121 public: 5122 RebuildRegionSetsClosure(bool free_list_only, 5123 HeapRegionSet* old_set, HeapRegionManager* hrm) : 5124 _free_list_only(free_list_only), 5125 _old_set(old_set), _hrm(hrm), _total_used(0) { 5126 assert(_hrm->num_free_regions() == 0, "pre-condition"); 5127 if (!free_list_only) { 5128 assert(_old_set->is_empty(), "pre-condition"); 5129 } 5130 } 5131 5132 bool doHeapRegion(HeapRegion* r) { 5133 if (r->is_empty()) { 5134 // Add free regions to the free list 5135 r->set_free(); 5136 r->set_allocation_context(AllocationContext::system()); 5137 _hrm->insert_into_free_list(r); 5138 } else if (!_free_list_only) { 5139 5140 if (r->is_humongous()) { 5141 // We ignore humongous regions. We left the humongous set unchanged. 5142 } else { 5143 assert(r->is_young() || r->is_free() || r->is_old(), "invariant"); 5144 // We now move all (non-humongous, non-old) regions to old gen, and register them as such. 5145 r->move_to_old(); 5146 _old_set->add(r); 5147 } 5148 _total_used += r->used(); 5149 } 5150 5151 return false; 5152 } 5153 5154 size_t total_used() { 5155 return _total_used; 5156 } 5157 }; 5158 5159 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { 5160 assert_at_safepoint(true /* should_be_vm_thread */); 5161 5162 if (!free_list_only) { 5163 _eden.clear(); 5164 _survivor.clear(); 5165 } 5166 5167 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm); 5168 heap_region_iterate(&cl); 5169 5170 if (!free_list_only) { 5171 set_used(cl.total_used()); 5172 if (_archive_allocator != NULL) { 5173 _archive_allocator->clear_used(); 5174 } 5175 } 5176 assert(used_unlocked() == recalculate_used(), 5177 "inconsistent used_unlocked(), " 5178 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT, 5179 used_unlocked(), recalculate_used()); 5180 } 5181 5182 bool G1CollectedHeap::is_in_closed_subset(const void* p) const { 5183 HeapRegion* hr = heap_region_containing(p); 5184 return hr->is_in(p); 5185 } 5186 5187 // Methods for the mutator alloc region 5188 5189 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 5190 bool force) { 5191 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 5192 bool should_allocate = g1_policy()->should_allocate_mutator_region(); 5193 if (force || should_allocate) { 5194 HeapRegion* new_alloc_region = new_region(word_size, 5195 false /* is_old */, 5196 false /* do_expand */); 5197 if (new_alloc_region != NULL) { 5198 set_region_short_lived_locked(new_alloc_region); 5199 _hr_printer.alloc(new_alloc_region, !should_allocate); 5200 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region); 5201 return new_alloc_region; 5202 } 5203 } 5204 return NULL; 5205 } 5206 5207 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 5208 size_t allocated_bytes) { 5209 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 5210 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden"); 5211 5212 collection_set()->add_eden_region(alloc_region); 5213 increase_used(allocated_bytes); 5214 _hr_printer.retire(alloc_region); 5215 // We update the eden sizes here, when the region is retired, 5216 // instead of when it's allocated, since this is the point that its 5217 // used space has been recored in _summary_bytes_used. 5218 g1mm()->update_eden_size(); 5219 } 5220 5221 // Methods for the GC alloc regions 5222 5223 bool G1CollectedHeap::has_more_regions(InCSetState dest) { 5224 if (dest.is_old()) { 5225 return true; 5226 } else { 5227 return survivor_regions_count() < g1_policy()->max_survivor_regions(); 5228 } 5229 } 5230 5231 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) { 5232 assert(FreeList_lock->owned_by_self(), "pre-condition"); 5233 5234 if (!has_more_regions(dest)) { 5235 return NULL; 5236 } 5237 5238 const bool is_survivor = dest.is_young(); 5239 5240 HeapRegion* new_alloc_region = new_region(word_size, 5241 !is_survivor, 5242 true /* do_expand */); 5243 if (new_alloc_region != NULL) { 5244 // We really only need to do this for old regions given that we 5245 // should never scan survivors. But it doesn't hurt to do it 5246 // for survivors too. 5247 new_alloc_region->record_timestamp(); 5248 if (is_survivor) { 5249 new_alloc_region->set_survivor(); 5250 _survivor.add(new_alloc_region); 5251 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region); 5252 } else { 5253 new_alloc_region->set_old(); 5254 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region); 5255 } 5256 _hr_printer.alloc(new_alloc_region); 5257 bool during_im = collector_state()->during_initial_mark_pause(); 5258 new_alloc_region->note_start_of_copying(during_im); 5259 return new_alloc_region; 5260 } 5261 return NULL; 5262 } 5263 5264 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 5265 size_t allocated_bytes, 5266 InCSetState dest) { 5267 bool during_im = collector_state()->during_initial_mark_pause(); 5268 alloc_region->note_end_of_copying(during_im); 5269 g1_policy()->record_bytes_copied_during_gc(allocated_bytes); 5270 if (dest.is_old()) { 5271 _old_set.add(alloc_region); 5272 } 5273 _hr_printer.retire(alloc_region); 5274 } 5275 5276 HeapRegion* G1CollectedHeap::alloc_highest_free_region() { 5277 bool expanded = false; 5278 uint index = _hrm.find_highest_free(&expanded); 5279 5280 if (index != G1_NO_HRM_INDEX) { 5281 if (expanded) { 5282 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B", 5283 HeapRegion::GrainWords * HeapWordSize); 5284 } 5285 _hrm.allocate_free_regions_starting_at(index, 1); 5286 return region_at(index); 5287 } 5288 return NULL; 5289 } 5290 5291 // Optimized nmethod scanning 5292 5293 class RegisterNMethodOopClosure: public OopClosure { 5294 G1CollectedHeap* _g1h; 5295 nmethod* _nm; 5296 5297 template <class T> void do_oop_work(T* p) { 5298 T heap_oop = oopDesc::load_heap_oop(p); 5299 if (!oopDesc::is_null(heap_oop)) { 5300 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 5301 HeapRegion* hr = _g1h->heap_region_containing(obj); 5302 assert(!hr->is_continues_humongous(), 5303 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 5304 " starting at " HR_FORMAT, 5305 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 5306 5307 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries. 5308 hr->add_strong_code_root_locked(_nm); 5309 } 5310 } 5311 5312 public: 5313 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 5314 _g1h(g1h), _nm(nm) {} 5315 5316 void do_oop(oop* p) { do_oop_work(p); } 5317 void do_oop(narrowOop* p) { do_oop_work(p); } 5318 }; 5319 5320 class UnregisterNMethodOopClosure: public OopClosure { 5321 G1CollectedHeap* _g1h; 5322 nmethod* _nm; 5323 5324 template <class T> void do_oop_work(T* p) { 5325 T heap_oop = oopDesc::load_heap_oop(p); 5326 if (!oopDesc::is_null(heap_oop)) { 5327 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 5328 HeapRegion* hr = _g1h->heap_region_containing(obj); 5329 assert(!hr->is_continues_humongous(), 5330 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 5331 " starting at " HR_FORMAT, 5332 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 5333 5334 hr->remove_strong_code_root(_nm); 5335 } 5336 } 5337 5338 public: 5339 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 5340 _g1h(g1h), _nm(nm) {} 5341 5342 void do_oop(oop* p) { do_oop_work(p); } 5343 void do_oop(narrowOop* p) { do_oop_work(p); } 5344 }; 5345 5346 // Returns true if the reference points to an object that 5347 // can move in an incremental collection. 5348 bool G1CollectedHeap::is_scavengable(oop obj) { 5349 HeapRegion* hr = heap_region_containing(obj); 5350 return !hr->is_pinned(); 5351 } 5352 5353 void G1CollectedHeap::register_nmethod(nmethod* nm) { 5354 guarantee(nm != NULL, "sanity"); 5355 RegisterNMethodOopClosure reg_cl(this, nm); 5356 nm->oops_do(®_cl); 5357 } 5358 5359 void G1CollectedHeap::unregister_nmethod(nmethod* nm) { 5360 guarantee(nm != NULL, "sanity"); 5361 UnregisterNMethodOopClosure reg_cl(this, nm); 5362 nm->oops_do(®_cl, true); 5363 } 5364 5365 void G1CollectedHeap::purge_code_root_memory() { 5366 double purge_start = os::elapsedTime(); 5367 G1CodeRootSet::purge(); 5368 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0; 5369 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms); 5370 } 5371 5372 class RebuildStrongCodeRootClosure: public CodeBlobClosure { 5373 G1CollectedHeap* _g1h; 5374 5375 public: 5376 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) : 5377 _g1h(g1h) {} 5378 5379 void do_code_blob(CodeBlob* cb) { 5380 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL; 5381 if (nm == NULL) { 5382 return; 5383 } 5384 5385 if (ScavengeRootsInCode) { 5386 _g1h->register_nmethod(nm); 5387 } 5388 } 5389 }; 5390 5391 void G1CollectedHeap::rebuild_strong_code_roots() { 5392 RebuildStrongCodeRootClosure blob_cl(this); 5393 CodeCache::blobs_do(&blob_cl); 5394 } 5395 5396 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() { 5397 GrowableArray<GCMemoryManager*> memory_managers(2); 5398 memory_managers.append(&_memory_manager); 5399 memory_managers.append(&_full_gc_memory_manager); 5400 return memory_managers; 5401 } 5402 5403 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() { 5404 GrowableArray<MemoryPool*> memory_pools(3); 5405 memory_pools.append(_eden_pool); 5406 memory_pools.append(_survivor_pool); 5407 memory_pools.append(_old_pool); 5408 return memory_pools; 5409 }