1 /* 2 * Copyright (c) 2001, 2015, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "classfile/metadataOnStackMark.hpp" 27 #include "classfile/stringTable.hpp" 28 #include "code/codeCache.hpp" 29 #include "code/icBuffer.hpp" 30 #include "gc/g1/bufferingOopClosure.hpp" 31 #include "gc/g1/concurrentG1Refine.hpp" 32 #include "gc/g1/concurrentG1RefineThread.hpp" 33 #include "gc/g1/concurrentMarkThread.inline.hpp" 34 #include "gc/g1/g1Allocator.inline.hpp" 35 #include "gc/g1/g1CollectedHeap.inline.hpp" 36 #include "gc/g1/g1CollectorPolicy.hpp" 37 #include "gc/g1/g1CollectorState.hpp" 38 #include "gc/g1/g1ErgoVerbose.hpp" 39 #include "gc/g1/g1EvacFailure.hpp" 40 #include "gc/g1/g1GCPhaseTimes.hpp" 41 #include "gc/g1/g1Log.hpp" 42 #include "gc/g1/g1MarkSweep.hpp" 43 #include "gc/g1/g1OopClosures.inline.hpp" 44 #include "gc/g1/g1ParScanThreadState.inline.hpp" 45 #include "gc/g1/g1RegionToSpaceMapper.hpp" 46 #include "gc/g1/g1RemSet.inline.hpp" 47 #include "gc/g1/g1RootClosures.hpp" 48 #include "gc/g1/g1RootProcessor.hpp" 49 #include "gc/g1/g1StringDedup.hpp" 50 #include "gc/g1/g1YCTypes.hpp" 51 #include "gc/g1/heapRegion.inline.hpp" 52 #include "gc/g1/heapRegionRemSet.hpp" 53 #include "gc/g1/heapRegionSet.inline.hpp" 54 #include "gc/g1/suspendibleThreadSet.hpp" 55 #include "gc/g1/vm_operations_g1.hpp" 56 #include "gc/shared/gcHeapSummary.hpp" 57 #include "gc/shared/gcId.hpp" 58 #include "gc/shared/gcLocker.inline.hpp" 59 #include "gc/shared/gcTimer.hpp" 60 #include "gc/shared/gcTrace.hpp" 61 #include "gc/shared/gcTraceTime.hpp" 62 #include "gc/shared/generationSpec.hpp" 63 #include "gc/shared/isGCActiveMark.hpp" 64 #include "gc/shared/referenceProcessor.hpp" 65 #include "gc/shared/taskqueue.inline.hpp" 66 #include "memory/allocation.hpp" 67 #include "memory/iterator.hpp" 68 #include "oops/oop.inline.hpp" 69 #include "runtime/atomic.inline.hpp" 70 #include "runtime/init.hpp" 71 #include "runtime/orderAccess.inline.hpp" 72 #include "runtime/vmThread.hpp" 73 #include "utilities/globalDefinitions.hpp" 74 #include "utilities/stack.inline.hpp" 75 76 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0; 77 78 // INVARIANTS/NOTES 79 // 80 // All allocation activity covered by the G1CollectedHeap interface is 81 // serialized by acquiring the HeapLock. This happens in mem_allocate 82 // and allocate_new_tlab, which are the "entry" points to the 83 // allocation code from the rest of the JVM. (Note that this does not 84 // apply to TLAB allocation, which is not part of this interface: it 85 // is done by clients of this interface.) 86 87 // Local to this file. 88 89 class RefineCardTableEntryClosure: public CardTableEntryClosure { 90 bool _concurrent; 91 public: 92 RefineCardTableEntryClosure() : _concurrent(true) { } 93 94 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 95 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false); 96 // This path is executed by the concurrent refine or mutator threads, 97 // concurrently, and so we do not care if card_ptr contains references 98 // that point into the collection set. 99 assert(!oops_into_cset, "should be"); 100 101 if (_concurrent && SuspendibleThreadSet::should_yield()) { 102 // Caller will actually yield. 103 return false; 104 } 105 // Otherwise, we finished successfully; return true. 106 return true; 107 } 108 109 void set_concurrent(bool b) { _concurrent = b; } 110 }; 111 112 113 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure { 114 private: 115 size_t _num_processed; 116 117 public: 118 RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { } 119 120 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 121 *card_ptr = CardTableModRefBS::dirty_card_val(); 122 _num_processed++; 123 return true; 124 } 125 126 size_t num_processed() const { return _num_processed; } 127 }; 128 129 130 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) { 131 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions); 132 } 133 134 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) { 135 // The from card cache is not the memory that is actually committed. So we cannot 136 // take advantage of the zero_filled parameter. 137 reset_from_card_cache(start_idx, num_regions); 138 } 139 140 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr) 141 { 142 // Claim the right to put the region on the dirty cards region list 143 // by installing a self pointer. 144 HeapRegion* next = hr->get_next_dirty_cards_region(); 145 if (next == NULL) { 146 HeapRegion* res = (HeapRegion*) 147 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(), 148 NULL); 149 if (res == NULL) { 150 HeapRegion* head; 151 do { 152 // Put the region to the dirty cards region list. 153 head = _dirty_cards_region_list; 154 next = (HeapRegion*) 155 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head); 156 if (next == head) { 157 assert(hr->get_next_dirty_cards_region() == hr, 158 "hr->get_next_dirty_cards_region() != hr"); 159 if (next == NULL) { 160 // The last region in the list points to itself. 161 hr->set_next_dirty_cards_region(hr); 162 } else { 163 hr->set_next_dirty_cards_region(next); 164 } 165 } 166 } while (next != head); 167 } 168 } 169 } 170 171 HeapRegion* G1CollectedHeap::pop_dirty_cards_region() 172 { 173 HeapRegion* head; 174 HeapRegion* hr; 175 do { 176 head = _dirty_cards_region_list; 177 if (head == NULL) { 178 return NULL; 179 } 180 HeapRegion* new_head = head->get_next_dirty_cards_region(); 181 if (head == new_head) { 182 // The last region. 183 new_head = NULL; 184 } 185 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list, 186 head); 187 } while (hr != head); 188 assert(hr != NULL, "invariant"); 189 hr->set_next_dirty_cards_region(NULL); 190 return hr; 191 } 192 193 // Returns true if the reference points to an object that 194 // can move in an incremental collection. 195 bool G1CollectedHeap::is_scavengable(const void* p) { 196 HeapRegion* hr = heap_region_containing(p); 197 return !hr->is_pinned(); 198 } 199 200 // Private methods. 201 202 HeapRegion* 203 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) { 204 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 205 while (!_secondary_free_list.is_empty() || free_regions_coming()) { 206 if (!_secondary_free_list.is_empty()) { 207 if (G1ConcRegionFreeingVerbose) { 208 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 209 "secondary_free_list has %u entries", 210 _secondary_free_list.length()); 211 } 212 // It looks as if there are free regions available on the 213 // secondary_free_list. Let's move them to the free_list and try 214 // again to allocate from it. 215 append_secondary_free_list(); 216 217 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not " 218 "empty we should have moved at least one entry to the free_list"); 219 HeapRegion* res = _hrm.allocate_free_region(is_old); 220 if (G1ConcRegionFreeingVerbose) { 221 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 222 "allocated " HR_FORMAT " from secondary_free_list", 223 HR_FORMAT_PARAMS(res)); 224 } 225 return res; 226 } 227 228 // Wait here until we get notified either when (a) there are no 229 // more free regions coming or (b) some regions have been moved on 230 // the secondary_free_list. 231 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 232 } 233 234 if (G1ConcRegionFreeingVerbose) { 235 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 236 "could not allocate from secondary_free_list"); 237 } 238 return NULL; 239 } 240 241 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) { 242 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords, 243 "the only time we use this to allocate a humongous region is " 244 "when we are allocating a single humongous region"); 245 246 HeapRegion* res; 247 if (G1StressConcRegionFreeing) { 248 if (!_secondary_free_list.is_empty()) { 249 if (G1ConcRegionFreeingVerbose) { 250 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 251 "forced to look at the secondary_free_list"); 252 } 253 res = new_region_try_secondary_free_list(is_old); 254 if (res != NULL) { 255 return res; 256 } 257 } 258 } 259 260 res = _hrm.allocate_free_region(is_old); 261 262 if (res == NULL) { 263 if (G1ConcRegionFreeingVerbose) { 264 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 265 "res == NULL, trying the secondary_free_list"); 266 } 267 res = new_region_try_secondary_free_list(is_old); 268 } 269 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) { 270 // Currently, only attempts to allocate GC alloc regions set 271 // do_expand to true. So, we should only reach here during a 272 // safepoint. If this assumption changes we might have to 273 // reconsider the use of _expand_heap_after_alloc_failure. 274 assert(SafepointSynchronize::is_at_safepoint(), "invariant"); 275 276 ergo_verbose1(ErgoHeapSizing, 277 "attempt heap expansion", 278 ergo_format_reason("region allocation request failed") 279 ergo_format_byte("allocation request"), 280 word_size * HeapWordSize); 281 if (expand(word_size * HeapWordSize)) { 282 // Given that expand() succeeded in expanding the heap, and we 283 // always expand the heap by an amount aligned to the heap 284 // region size, the free list should in theory not be empty. 285 // In either case allocate_free_region() will check for NULL. 286 res = _hrm.allocate_free_region(is_old); 287 } else { 288 _expand_heap_after_alloc_failure = false; 289 } 290 } 291 return res; 292 } 293 294 HeapWord* 295 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first, 296 uint num_regions, 297 size_t word_size, 298 AllocationContext_t context) { 299 assert(first != G1_NO_HRM_INDEX, "pre-condition"); 300 assert(is_humongous(word_size), "word_size should be humongous"); 301 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition"); 302 303 // Index of last region in the series + 1. 304 uint last = first + num_regions; 305 306 // We need to initialize the region(s) we just discovered. This is 307 // a bit tricky given that it can happen concurrently with 308 // refinement threads refining cards on these regions and 309 // potentially wanting to refine the BOT as they are scanning 310 // those cards (this can happen shortly after a cleanup; see CR 311 // 6991377). So we have to set up the region(s) carefully and in 312 // a specific order. 313 314 // The word size sum of all the regions we will allocate. 315 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords; 316 assert(word_size <= word_size_sum, "sanity"); 317 318 // This will be the "starts humongous" region. 319 HeapRegion* first_hr = region_at(first); 320 // The header of the new object will be placed at the bottom of 321 // the first region. 322 HeapWord* new_obj = first_hr->bottom(); 323 // This will be the new top of the new object. 324 HeapWord* obj_top = new_obj + word_size; 325 326 // First, we need to zero the header of the space that we will be 327 // allocating. When we update top further down, some refinement 328 // threads might try to scan the region. By zeroing the header we 329 // ensure that any thread that will try to scan the region will 330 // come across the zero klass word and bail out. 331 // 332 // NOTE: It would not have been correct to have used 333 // CollectedHeap::fill_with_object() and make the space look like 334 // an int array. The thread that is doing the allocation will 335 // later update the object header to a potentially different array 336 // type and, for a very short period of time, the klass and length 337 // fields will be inconsistent. This could cause a refinement 338 // thread to calculate the object size incorrectly. 339 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0); 340 341 // We will set up the first region as "starts humongous". This 342 // will also update the BOT covering all the regions to reflect 343 // that there is a single object that starts at the bottom of the 344 // first region. 345 first_hr->set_starts_humongous(obj_top); 346 first_hr->set_allocation_context(context); 347 // Then, if there are any, we will set up the "continues 348 // humongous" regions. 349 HeapRegion* hr = NULL; 350 for (uint i = first + 1; i < last; ++i) { 351 hr = region_at(i); 352 hr->set_continues_humongous(first_hr); 353 hr->set_allocation_context(context); 354 } 355 356 // Up to this point no concurrent thread would have been able to 357 // do any scanning on any region in this series. All the top 358 // fields still point to bottom, so the intersection between 359 // [bottom,top] and [card_start,card_end] will be empty. Before we 360 // update the top fields, we'll do a storestore to make sure that 361 // no thread sees the update to top before the zeroing of the 362 // object header and the BOT initialization. 363 OrderAccess::storestore(); 364 365 // Now that the BOT and the object header have been initialized, 366 // we can update top of the "starts humongous" region. 367 first_hr->set_top(MIN2(first_hr->end(), obj_top)); 368 if (_hr_printer.is_active()) { 369 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, first_hr->top()); 370 } 371 372 // Now, we will update the top fields of the "continues humongous" 373 // regions. The reason we need to do this is that, otherwise, 374 // these regions would look empty and this will confuse parts of 375 // G1. For example, the code that looks for a consecutive number 376 // of empty regions will consider them empty and try to 377 // re-allocate them. We can extend is_empty() to also include 378 // !is_continues_humongous(), but it is easier to just update the top 379 // fields here. The way we set top for all regions (i.e., top == 380 // end for all regions but the last one, top == new_top for the 381 // last one) is actually used when we will free up the humongous 382 // region in free_humongous_region(). 383 hr = NULL; 384 for (uint i = first + 1; i < last; ++i) { 385 hr = region_at(i); 386 if ((i + 1) == last) { 387 // last continues humongous region 388 assert(hr->bottom() < obj_top && obj_top <= hr->end(), 389 "new_top should fall on this region"); 390 hr->set_top(obj_top); 391 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, obj_top); 392 } else { 393 // not last one 394 assert(obj_top > hr->end(), "obj_top should be above this region"); 395 hr->set_top(hr->end()); 396 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end()); 397 } 398 } 399 // If we have continues humongous regions (hr != NULL), its top should 400 // match obj_top. 401 assert(hr == NULL || (hr->top() == obj_top), "sanity"); 402 check_bitmaps("Humongous Region Allocation", first_hr); 403 404 increase_used(word_size * HeapWordSize); 405 406 for (uint i = first; i < last; ++i) { 407 _humongous_set.add(region_at(i)); 408 } 409 410 return new_obj; 411 } 412 413 // If could fit into free regions w/o expansion, try. 414 // Otherwise, if can expand, do so. 415 // Otherwise, if using ex regions might help, try with ex given back. 416 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) { 417 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 418 419 verify_region_sets_optional(); 420 421 uint first = G1_NO_HRM_INDEX; 422 uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords); 423 424 if (obj_regions == 1) { 425 // Only one region to allocate, try to use a fast path by directly allocating 426 // from the free lists. Do not try to expand here, we will potentially do that 427 // later. 428 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */); 429 if (hr != NULL) { 430 first = hr->hrm_index(); 431 } 432 } else { 433 // We can't allocate humongous regions spanning more than one region while 434 // cleanupComplete() is running, since some of the regions we find to be 435 // empty might not yet be added to the free list. It is not straightforward 436 // to know in which list they are on so that we can remove them. We only 437 // need to do this if we need to allocate more than one region to satisfy the 438 // current humongous allocation request. If we are only allocating one region 439 // we use the one-region region allocation code (see above), that already 440 // potentially waits for regions from the secondary free list. 441 wait_while_free_regions_coming(); 442 append_secondary_free_list_if_not_empty_with_lock(); 443 444 // Policy: Try only empty regions (i.e. already committed first). Maybe we 445 // are lucky enough to find some. 446 first = _hrm.find_contiguous_only_empty(obj_regions); 447 if (first != G1_NO_HRM_INDEX) { 448 _hrm.allocate_free_regions_starting_at(first, obj_regions); 449 } 450 } 451 452 if (first == G1_NO_HRM_INDEX) { 453 // Policy: We could not find enough regions for the humongous object in the 454 // free list. Look through the heap to find a mix of free and uncommitted regions. 455 // If so, try expansion. 456 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions); 457 if (first != G1_NO_HRM_INDEX) { 458 // We found something. Make sure these regions are committed, i.e. expand 459 // the heap. Alternatively we could do a defragmentation GC. 460 ergo_verbose1(ErgoHeapSizing, 461 "attempt heap expansion", 462 ergo_format_reason("humongous allocation request failed") 463 ergo_format_byte("allocation request"), 464 word_size * HeapWordSize); 465 466 _hrm.expand_at(first, obj_regions); 467 g1_policy()->record_new_heap_size(num_regions()); 468 469 #ifdef ASSERT 470 for (uint i = first; i < first + obj_regions; ++i) { 471 HeapRegion* hr = region_at(i); 472 assert(hr->is_free(), "sanity"); 473 assert(hr->is_empty(), "sanity"); 474 assert(is_on_master_free_list(hr), "sanity"); 475 } 476 #endif 477 _hrm.allocate_free_regions_starting_at(first, obj_regions); 478 } else { 479 // Policy: Potentially trigger a defragmentation GC. 480 } 481 } 482 483 HeapWord* result = NULL; 484 if (first != G1_NO_HRM_INDEX) { 485 result = humongous_obj_allocate_initialize_regions(first, obj_regions, 486 word_size, context); 487 assert(result != NULL, "it should always return a valid result"); 488 489 // A successful humongous object allocation changes the used space 490 // information of the old generation so we need to recalculate the 491 // sizes and update the jstat counters here. 492 g1mm()->update_sizes(); 493 } 494 495 verify_region_sets_optional(); 496 497 return result; 498 } 499 500 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) { 501 assert_heap_not_locked_and_not_at_safepoint(); 502 assert(!is_humongous(word_size), "we do not allow humongous TLABs"); 503 504 uint dummy_gc_count_before; 505 uint dummy_gclocker_retry_count = 0; 506 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count); 507 } 508 509 HeapWord* 510 G1CollectedHeap::mem_allocate(size_t word_size, 511 bool* gc_overhead_limit_was_exceeded) { 512 assert_heap_not_locked_and_not_at_safepoint(); 513 514 // Loop until the allocation is satisfied, or unsatisfied after GC. 515 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 516 uint gc_count_before; 517 518 HeapWord* result = NULL; 519 if (!is_humongous(word_size)) { 520 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count); 521 } else { 522 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count); 523 } 524 if (result != NULL) { 525 return result; 526 } 527 528 // Create the garbage collection operation... 529 VM_G1CollectForAllocation op(gc_count_before, word_size); 530 op.set_allocation_context(AllocationContext::current()); 531 532 // ...and get the VM thread to execute it. 533 VMThread::execute(&op); 534 535 if (op.prologue_succeeded() && op.pause_succeeded()) { 536 // If the operation was successful we'll return the result even 537 // if it is NULL. If the allocation attempt failed immediately 538 // after a Full GC, it's unlikely we'll be able to allocate now. 539 HeapWord* result = op.result(); 540 if (result != NULL && !is_humongous(word_size)) { 541 // Allocations that take place on VM operations do not do any 542 // card dirtying and we have to do it here. We only have to do 543 // this for non-humongous allocations, though. 544 dirty_young_block(result, word_size); 545 } 546 return result; 547 } else { 548 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 549 return NULL; 550 } 551 assert(op.result() == NULL, 552 "the result should be NULL if the VM op did not succeed"); 553 } 554 555 // Give a warning if we seem to be looping forever. 556 if ((QueuedAllocationWarningCount > 0) && 557 (try_count % QueuedAllocationWarningCount == 0)) { 558 warning("G1CollectedHeap::mem_allocate retries %d times", try_count); 559 } 560 } 561 562 ShouldNotReachHere(); 563 return NULL; 564 } 565 566 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size, 567 AllocationContext_t context, 568 uint* gc_count_before_ret, 569 uint* gclocker_retry_count_ret) { 570 // Make sure you read the note in attempt_allocation_humongous(). 571 572 assert_heap_not_locked_and_not_at_safepoint(); 573 assert(!is_humongous(word_size), "attempt_allocation_slow() should not " 574 "be called for humongous allocation requests"); 575 576 // We should only get here after the first-level allocation attempt 577 // (attempt_allocation()) failed to allocate. 578 579 // We will loop until a) we manage to successfully perform the 580 // allocation or b) we successfully schedule a collection which 581 // fails to perform the allocation. b) is the only case when we'll 582 // return NULL. 583 HeapWord* result = NULL; 584 for (int try_count = 1; /* we'll return */; try_count += 1) { 585 bool should_try_gc; 586 uint gc_count_before; 587 588 { 589 MutexLockerEx x(Heap_lock); 590 result = _allocator->attempt_allocation_locked(word_size, context); 591 if (result != NULL) { 592 return result; 593 } 594 595 if (GC_locker::is_active_and_needs_gc()) { 596 if (g1_policy()->can_expand_young_list()) { 597 // No need for an ergo verbose message here, 598 // can_expand_young_list() does this when it returns true. 599 result = _allocator->attempt_allocation_force(word_size, context); 600 if (result != NULL) { 601 return result; 602 } 603 } 604 should_try_gc = false; 605 } else { 606 // The GCLocker may not be active but the GCLocker initiated 607 // GC may not yet have been performed (GCLocker::needs_gc() 608 // returns true). In this case we do not try this GC and 609 // wait until the GCLocker initiated GC is performed, and 610 // then retry the allocation. 611 if (GC_locker::needs_gc()) { 612 should_try_gc = false; 613 } else { 614 // Read the GC count while still holding the Heap_lock. 615 gc_count_before = total_collections(); 616 should_try_gc = true; 617 } 618 } 619 } 620 621 if (should_try_gc) { 622 bool succeeded; 623 result = do_collection_pause(word_size, gc_count_before, &succeeded, 624 GCCause::_g1_inc_collection_pause); 625 if (result != NULL) { 626 assert(succeeded, "only way to get back a non-NULL result"); 627 return result; 628 } 629 630 if (succeeded) { 631 // If we get here we successfully scheduled a collection which 632 // failed to allocate. No point in trying to allocate 633 // further. We'll just return NULL. 634 MutexLockerEx x(Heap_lock); 635 *gc_count_before_ret = total_collections(); 636 return NULL; 637 } 638 } else { 639 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { 640 MutexLockerEx x(Heap_lock); 641 *gc_count_before_ret = total_collections(); 642 return NULL; 643 } 644 // The GCLocker is either active or the GCLocker initiated 645 // GC has not yet been performed. Stall until it is and 646 // then retry the allocation. 647 GC_locker::stall_until_clear(); 648 (*gclocker_retry_count_ret) += 1; 649 } 650 651 // We can reach here if we were unsuccessful in scheduling a 652 // collection (because another thread beat us to it) or if we were 653 // stalled due to the GC locker. In either can we should retry the 654 // allocation attempt in case another thread successfully 655 // performed a collection and reclaimed enough space. We do the 656 // first attempt (without holding the Heap_lock) here and the 657 // follow-on attempt will be at the start of the next loop 658 // iteration (after taking the Heap_lock). 659 result = _allocator->attempt_allocation(word_size, context); 660 if (result != NULL) { 661 return result; 662 } 663 664 // Give a warning if we seem to be looping forever. 665 if ((QueuedAllocationWarningCount > 0) && 666 (try_count % QueuedAllocationWarningCount == 0)) { 667 warning("G1CollectedHeap::attempt_allocation_slow() " 668 "retries %d times", try_count); 669 } 670 } 671 672 ShouldNotReachHere(); 673 return NULL; 674 } 675 676 void G1CollectedHeap::begin_archive_alloc_range() { 677 assert_at_safepoint(true /* should_be_vm_thread */); 678 if (_archive_allocator == NULL) { 679 _archive_allocator = G1ArchiveAllocator::create_allocator(this); 680 } 681 } 682 683 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) { 684 // Allocations in archive regions cannot be of a size that would be considered 685 // humongous even for a minimum-sized region, because G1 region sizes/boundaries 686 // may be different at archive-restore time. 687 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words()); 688 } 689 690 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) { 691 assert_at_safepoint(true /* should_be_vm_thread */); 692 assert(_archive_allocator != NULL, "_archive_allocator not initialized"); 693 if (is_archive_alloc_too_large(word_size)) { 694 return NULL; 695 } 696 return _archive_allocator->archive_mem_allocate(word_size); 697 } 698 699 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges, 700 size_t end_alignment_in_bytes) { 701 assert_at_safepoint(true /* should_be_vm_thread */); 702 assert(_archive_allocator != NULL, "_archive_allocator not initialized"); 703 704 // Call complete_archive to do the real work, filling in the MemRegion 705 // array with the archive regions. 706 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes); 707 delete _archive_allocator; 708 _archive_allocator = NULL; 709 } 710 711 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) { 712 assert(ranges != NULL, "MemRegion array NULL"); 713 assert(count != 0, "No MemRegions provided"); 714 MemRegion reserved = _hrm.reserved(); 715 for (size_t i = 0; i < count; i++) { 716 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) { 717 return false; 718 } 719 } 720 return true; 721 } 722 723 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) { 724 assert(!is_init_completed(), "Expect to be called at JVM init time"); 725 assert(ranges != NULL, "MemRegion array NULL"); 726 assert(count != 0, "No MemRegions provided"); 727 MutexLockerEx x(Heap_lock); 728 729 MemRegion reserved = _hrm.reserved(); 730 HeapWord* prev_last_addr = NULL; 731 HeapRegion* prev_last_region = NULL; 732 733 // Temporarily disable pretouching of heap pages. This interface is used 734 // when mmap'ing archived heap data in, so pre-touching is wasted. 735 FlagSetting fs(AlwaysPreTouch, false); 736 737 // Enable archive object checking in G1MarkSweep. We have to let it know 738 // about each archive range, so that objects in those ranges aren't marked. 739 G1MarkSweep::enable_archive_object_check(); 740 741 // For each specified MemRegion range, allocate the corresponding G1 742 // regions and mark them as archive regions. We expect the ranges in 743 // ascending starting address order, without overlap. 744 for (size_t i = 0; i < count; i++) { 745 MemRegion curr_range = ranges[i]; 746 HeapWord* start_address = curr_range.start(); 747 size_t word_size = curr_range.word_size(); 748 HeapWord* last_address = curr_range.last(); 749 size_t commits = 0; 750 751 guarantee(reserved.contains(start_address) && reserved.contains(last_address), 752 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 753 p2i(start_address), p2i(last_address)); 754 guarantee(start_address > prev_last_addr, 755 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 756 p2i(start_address), p2i(prev_last_addr)); 757 prev_last_addr = last_address; 758 759 // Check for ranges that start in the same G1 region in which the previous 760 // range ended, and adjust the start address so we don't try to allocate 761 // the same region again. If the current range is entirely within that 762 // region, skip it, just adjusting the recorded top. 763 HeapRegion* start_region = _hrm.addr_to_region(start_address); 764 if ((prev_last_region != NULL) && (start_region == prev_last_region)) { 765 start_address = start_region->end(); 766 if (start_address > last_address) { 767 increase_used(word_size * HeapWordSize); 768 start_region->set_top(last_address + 1); 769 continue; 770 } 771 start_region->set_top(start_address); 772 curr_range = MemRegion(start_address, last_address + 1); 773 start_region = _hrm.addr_to_region(start_address); 774 } 775 776 // Perform the actual region allocation, exiting if it fails. 777 // Then note how much new space we have allocated. 778 if (!_hrm.allocate_containing_regions(curr_range, &commits)) { 779 return false; 780 } 781 increase_used(word_size * HeapWordSize); 782 if (commits != 0) { 783 ergo_verbose1(ErgoHeapSizing, 784 "attempt heap expansion", 785 ergo_format_reason("allocate archive regions") 786 ergo_format_byte("total size"), 787 HeapRegion::GrainWords * HeapWordSize * commits); 788 } 789 790 // Mark each G1 region touched by the range as archive, add it to the old set, 791 // and set the allocation context and top. 792 HeapRegion* curr_region = _hrm.addr_to_region(start_address); 793 HeapRegion* last_region = _hrm.addr_to_region(last_address); 794 prev_last_region = last_region; 795 796 while (curr_region != NULL) { 797 assert(curr_region->is_empty() && !curr_region->is_pinned(), 798 "Region already in use (index %u)", curr_region->hrm_index()); 799 _hr_printer.alloc(curr_region, G1HRPrinter::Archive); 800 curr_region->set_allocation_context(AllocationContext::system()); 801 curr_region->set_archive(); 802 _old_set.add(curr_region); 803 if (curr_region != last_region) { 804 curr_region->set_top(curr_region->end()); 805 curr_region = _hrm.next_region_in_heap(curr_region); 806 } else { 807 curr_region->set_top(last_address + 1); 808 curr_region = NULL; 809 } 810 } 811 812 // Notify mark-sweep of the archive range. 813 G1MarkSweep::set_range_archive(curr_range, true); 814 } 815 return true; 816 } 817 818 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) { 819 assert(!is_init_completed(), "Expect to be called at JVM init time"); 820 assert(ranges != NULL, "MemRegion array NULL"); 821 assert(count != 0, "No MemRegions provided"); 822 MemRegion reserved = _hrm.reserved(); 823 HeapWord *prev_last_addr = NULL; 824 HeapRegion* prev_last_region = NULL; 825 826 // For each MemRegion, create filler objects, if needed, in the G1 regions 827 // that contain the address range. The address range actually within the 828 // MemRegion will not be modified. That is assumed to have been initialized 829 // elsewhere, probably via an mmap of archived heap data. 830 MutexLockerEx x(Heap_lock); 831 for (size_t i = 0; i < count; i++) { 832 HeapWord* start_address = ranges[i].start(); 833 HeapWord* last_address = ranges[i].last(); 834 835 assert(reserved.contains(start_address) && reserved.contains(last_address), 836 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 837 p2i(start_address), p2i(last_address)); 838 assert(start_address > prev_last_addr, 839 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 840 p2i(start_address), p2i(prev_last_addr)); 841 842 HeapRegion* start_region = _hrm.addr_to_region(start_address); 843 HeapRegion* last_region = _hrm.addr_to_region(last_address); 844 HeapWord* bottom_address = start_region->bottom(); 845 846 // Check for a range beginning in the same region in which the 847 // previous one ended. 848 if (start_region == prev_last_region) { 849 bottom_address = prev_last_addr + 1; 850 } 851 852 // Verify that the regions were all marked as archive regions by 853 // alloc_archive_regions. 854 HeapRegion* curr_region = start_region; 855 while (curr_region != NULL) { 856 guarantee(curr_region->is_archive(), 857 "Expected archive region at index %u", curr_region->hrm_index()); 858 if (curr_region != last_region) { 859 curr_region = _hrm.next_region_in_heap(curr_region); 860 } else { 861 curr_region = NULL; 862 } 863 } 864 865 prev_last_addr = last_address; 866 prev_last_region = last_region; 867 868 // Fill the memory below the allocated range with dummy object(s), 869 // if the region bottom does not match the range start, or if the previous 870 // range ended within the same G1 region, and there is a gap. 871 if (start_address != bottom_address) { 872 size_t fill_size = pointer_delta(start_address, bottom_address); 873 G1CollectedHeap::fill_with_objects(bottom_address, fill_size); 874 increase_used(fill_size * HeapWordSize); 875 } 876 } 877 } 878 879 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size, 880 uint* gc_count_before_ret, 881 uint* gclocker_retry_count_ret) { 882 assert_heap_not_locked_and_not_at_safepoint(); 883 assert(!is_humongous(word_size), "attempt_allocation() should not " 884 "be called for humongous allocation requests"); 885 886 AllocationContext_t context = AllocationContext::current(); 887 HeapWord* result = _allocator->attempt_allocation(word_size, context); 888 889 if (result == NULL) { 890 result = attempt_allocation_slow(word_size, 891 context, 892 gc_count_before_ret, 893 gclocker_retry_count_ret); 894 } 895 assert_heap_not_locked(); 896 if (result != NULL) { 897 dirty_young_block(result, word_size); 898 } 899 return result; 900 } 901 902 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) { 903 assert(!is_init_completed(), "Expect to be called at JVM init time"); 904 assert(ranges != NULL, "MemRegion array NULL"); 905 assert(count != 0, "No MemRegions provided"); 906 MemRegion reserved = _hrm.reserved(); 907 HeapWord* prev_last_addr = NULL; 908 HeapRegion* prev_last_region = NULL; 909 size_t size_used = 0; 910 size_t uncommitted_regions = 0; 911 912 // For each Memregion, free the G1 regions that constitute it, and 913 // notify mark-sweep that the range is no longer to be considered 'archive.' 914 MutexLockerEx x(Heap_lock); 915 for (size_t i = 0; i < count; i++) { 916 HeapWord* start_address = ranges[i].start(); 917 HeapWord* last_address = ranges[i].last(); 918 919 assert(reserved.contains(start_address) && reserved.contains(last_address), 920 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 921 p2i(start_address), p2i(last_address)); 922 assert(start_address > prev_last_addr, 923 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 924 p2i(start_address), p2i(prev_last_addr)); 925 size_used += ranges[i].byte_size(); 926 prev_last_addr = last_address; 927 928 HeapRegion* start_region = _hrm.addr_to_region(start_address); 929 HeapRegion* last_region = _hrm.addr_to_region(last_address); 930 931 // Check for ranges that start in the same G1 region in which the previous 932 // range ended, and adjust the start address so we don't try to free 933 // the same region again. If the current range is entirely within that 934 // region, skip it. 935 if (start_region == prev_last_region) { 936 start_address = start_region->end(); 937 if (start_address > last_address) { 938 continue; 939 } 940 start_region = _hrm.addr_to_region(start_address); 941 } 942 prev_last_region = last_region; 943 944 // After verifying that each region was marked as an archive region by 945 // alloc_archive_regions, set it free and empty and uncommit it. 946 HeapRegion* curr_region = start_region; 947 while (curr_region != NULL) { 948 guarantee(curr_region->is_archive(), 949 "Expected archive region at index %u", curr_region->hrm_index()); 950 uint curr_index = curr_region->hrm_index(); 951 _old_set.remove(curr_region); 952 curr_region->set_free(); 953 curr_region->set_top(curr_region->bottom()); 954 if (curr_region != last_region) { 955 curr_region = _hrm.next_region_in_heap(curr_region); 956 } else { 957 curr_region = NULL; 958 } 959 _hrm.shrink_at(curr_index, 1); 960 uncommitted_regions++; 961 } 962 963 // Notify mark-sweep that this is no longer an archive range. 964 G1MarkSweep::set_range_archive(ranges[i], false); 965 } 966 967 if (uncommitted_regions != 0) { 968 ergo_verbose1(ErgoHeapSizing, 969 "attempt heap shrinking", 970 ergo_format_reason("uncommitted archive regions") 971 ergo_format_byte("total size"), 972 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions); 973 } 974 decrease_used(size_used); 975 } 976 977 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size, 978 uint* gc_count_before_ret, 979 uint* gclocker_retry_count_ret) { 980 // The structure of this method has a lot of similarities to 981 // attempt_allocation_slow(). The reason these two were not merged 982 // into a single one is that such a method would require several "if 983 // allocation is not humongous do this, otherwise do that" 984 // conditional paths which would obscure its flow. In fact, an early 985 // version of this code did use a unified method which was harder to 986 // follow and, as a result, it had subtle bugs that were hard to 987 // track down. So keeping these two methods separate allows each to 988 // be more readable. It will be good to keep these two in sync as 989 // much as possible. 990 991 assert_heap_not_locked_and_not_at_safepoint(); 992 assert(is_humongous(word_size), "attempt_allocation_humongous() " 993 "should only be called for humongous allocations"); 994 995 // Humongous objects can exhaust the heap quickly, so we should check if we 996 // need to start a marking cycle at each humongous object allocation. We do 997 // the check before we do the actual allocation. The reason for doing it 998 // before the allocation is that we avoid having to keep track of the newly 999 // allocated memory while we do a GC. 1000 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation", 1001 word_size)) { 1002 collect(GCCause::_g1_humongous_allocation); 1003 } 1004 1005 // We will loop until a) we manage to successfully perform the 1006 // allocation or b) we successfully schedule a collection which 1007 // fails to perform the allocation. b) is the only case when we'll 1008 // return NULL. 1009 HeapWord* result = NULL; 1010 for (int try_count = 1; /* we'll return */; try_count += 1) { 1011 bool should_try_gc; 1012 uint gc_count_before; 1013 1014 { 1015 MutexLockerEx x(Heap_lock); 1016 1017 // Given that humongous objects are not allocated in young 1018 // regions, we'll first try to do the allocation without doing a 1019 // collection hoping that there's enough space in the heap. 1020 result = humongous_obj_allocate(word_size, AllocationContext::current()); 1021 if (result != NULL) { 1022 return result; 1023 } 1024 1025 if (GC_locker::is_active_and_needs_gc()) { 1026 should_try_gc = false; 1027 } else { 1028 // The GCLocker may not be active but the GCLocker initiated 1029 // GC may not yet have been performed (GCLocker::needs_gc() 1030 // returns true). In this case we do not try this GC and 1031 // wait until the GCLocker initiated GC is performed, and 1032 // then retry the allocation. 1033 if (GC_locker::needs_gc()) { 1034 should_try_gc = false; 1035 } else { 1036 // Read the GC count while still holding the Heap_lock. 1037 gc_count_before = total_collections(); 1038 should_try_gc = true; 1039 } 1040 } 1041 } 1042 1043 if (should_try_gc) { 1044 // If we failed to allocate the humongous object, we should try to 1045 // do a collection pause (if we're allowed) in case it reclaims 1046 // enough space for the allocation to succeed after the pause. 1047 1048 bool succeeded; 1049 result = do_collection_pause(word_size, gc_count_before, &succeeded, 1050 GCCause::_g1_humongous_allocation); 1051 if (result != NULL) { 1052 assert(succeeded, "only way to get back a non-NULL result"); 1053 return result; 1054 } 1055 1056 if (succeeded) { 1057 // If we get here we successfully scheduled a collection which 1058 // failed to allocate. No point in trying to allocate 1059 // further. We'll just return NULL. 1060 MutexLockerEx x(Heap_lock); 1061 *gc_count_before_ret = total_collections(); 1062 return NULL; 1063 } 1064 } else { 1065 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { 1066 MutexLockerEx x(Heap_lock); 1067 *gc_count_before_ret = total_collections(); 1068 return NULL; 1069 } 1070 // The GCLocker is either active or the GCLocker initiated 1071 // GC has not yet been performed. Stall until it is and 1072 // then retry the allocation. 1073 GC_locker::stall_until_clear(); 1074 (*gclocker_retry_count_ret) += 1; 1075 } 1076 1077 // We can reach here if we were unsuccessful in scheduling a 1078 // collection (because another thread beat us to it) or if we were 1079 // stalled due to the GC locker. In either can we should retry the 1080 // allocation attempt in case another thread successfully 1081 // performed a collection and reclaimed enough space. Give a 1082 // warning if we seem to be looping forever. 1083 1084 if ((QueuedAllocationWarningCount > 0) && 1085 (try_count % QueuedAllocationWarningCount == 0)) { 1086 warning("G1CollectedHeap::attempt_allocation_humongous() " 1087 "retries %d times", try_count); 1088 } 1089 } 1090 1091 ShouldNotReachHere(); 1092 return NULL; 1093 } 1094 1095 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size, 1096 AllocationContext_t context, 1097 bool expect_null_mutator_alloc_region) { 1098 assert_at_safepoint(true /* should_be_vm_thread */); 1099 assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region, 1100 "the current alloc region was unexpectedly found to be non-NULL"); 1101 1102 if (!is_humongous(word_size)) { 1103 return _allocator->attempt_allocation_locked(word_size, context); 1104 } else { 1105 HeapWord* result = humongous_obj_allocate(word_size, context); 1106 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) { 1107 collector_state()->set_initiate_conc_mark_if_possible(true); 1108 } 1109 return result; 1110 } 1111 1112 ShouldNotReachHere(); 1113 } 1114 1115 class PostMCRemSetClearClosure: public HeapRegionClosure { 1116 G1CollectedHeap* _g1h; 1117 ModRefBarrierSet* _mr_bs; 1118 public: 1119 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) : 1120 _g1h(g1h), _mr_bs(mr_bs) {} 1121 1122 bool doHeapRegion(HeapRegion* r) { 1123 HeapRegionRemSet* hrrs = r->rem_set(); 1124 1125 _g1h->reset_gc_time_stamps(r); 1126 1127 if (r->is_continues_humongous()) { 1128 // We'll assert that the strong code root list and RSet is empty 1129 assert(hrrs->strong_code_roots_list_length() == 0, "sanity"); 1130 assert(hrrs->occupied() == 0, "RSet should be empty"); 1131 } else { 1132 hrrs->clear(); 1133 } 1134 // You might think here that we could clear just the cards 1135 // corresponding to the used region. But no: if we leave a dirty card 1136 // in a region we might allocate into, then it would prevent that card 1137 // from being enqueued, and cause it to be missed. 1138 // Re: the performance cost: we shouldn't be doing full GC anyway! 1139 _mr_bs->clear(MemRegion(r->bottom(), r->end())); 1140 1141 return false; 1142 } 1143 }; 1144 1145 void G1CollectedHeap::clear_rsets_post_compaction() { 1146 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set()); 1147 heap_region_iterate(&rs_clear); 1148 } 1149 1150 class RebuildRSOutOfRegionClosure: public HeapRegionClosure { 1151 G1CollectedHeap* _g1h; 1152 UpdateRSOopClosure _cl; 1153 public: 1154 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) : 1155 _cl(g1->g1_rem_set(), worker_i), 1156 _g1h(g1) 1157 { } 1158 1159 bool doHeapRegion(HeapRegion* r) { 1160 if (!r->is_continues_humongous()) { 1161 _cl.set_from(r); 1162 r->oop_iterate(&_cl); 1163 } 1164 return false; 1165 } 1166 }; 1167 1168 class ParRebuildRSTask: public AbstractGangTask { 1169 G1CollectedHeap* _g1; 1170 HeapRegionClaimer _hrclaimer; 1171 1172 public: 1173 ParRebuildRSTask(G1CollectedHeap* g1) : 1174 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {} 1175 1176 void work(uint worker_id) { 1177 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id); 1178 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer); 1179 } 1180 }; 1181 1182 class PostCompactionPrinterClosure: public HeapRegionClosure { 1183 private: 1184 G1HRPrinter* _hr_printer; 1185 public: 1186 bool doHeapRegion(HeapRegion* hr) { 1187 assert(!hr->is_young(), "not expecting to find young regions"); 1188 if (hr->is_free()) { 1189 // We only generate output for non-empty regions. 1190 } else if (hr->is_starts_humongous()) { 1191 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous); 1192 } else if (hr->is_continues_humongous()) { 1193 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous); 1194 } else if (hr->is_archive()) { 1195 _hr_printer->post_compaction(hr, G1HRPrinter::Archive); 1196 } else if (hr->is_old()) { 1197 _hr_printer->post_compaction(hr, G1HRPrinter::Old); 1198 } else { 1199 ShouldNotReachHere(); 1200 } 1201 return false; 1202 } 1203 1204 PostCompactionPrinterClosure(G1HRPrinter* hr_printer) 1205 : _hr_printer(hr_printer) { } 1206 }; 1207 1208 void G1CollectedHeap::print_hrm_post_compaction() { 1209 PostCompactionPrinterClosure cl(hr_printer()); 1210 heap_region_iterate(&cl); 1211 } 1212 1213 bool G1CollectedHeap::do_collection(bool explicit_gc, 1214 bool clear_all_soft_refs, 1215 size_t word_size) { 1216 assert_at_safepoint(true /* should_be_vm_thread */); 1217 1218 if (GC_locker::check_active_before_gc()) { 1219 return false; 1220 } 1221 1222 STWGCTimer* gc_timer = G1MarkSweep::gc_timer(); 1223 gc_timer->register_gc_start(); 1224 1225 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer(); 1226 GCIdMark gc_id_mark; 1227 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start()); 1228 1229 SvcGCMarker sgcm(SvcGCMarker::FULL); 1230 ResourceMark rm; 1231 1232 G1Log::update_level(); 1233 print_heap_before_gc(); 1234 trace_heap_before_gc(gc_tracer); 1235 1236 size_t metadata_prev_used = MetaspaceAux::used_bytes(); 1237 1238 verify_region_sets_optional(); 1239 1240 const bool do_clear_all_soft_refs = clear_all_soft_refs || 1241 collector_policy()->should_clear_all_soft_refs(); 1242 1243 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy()); 1244 1245 { 1246 IsGCActiveMark x; 1247 1248 // Timing 1249 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant"); 1250 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty); 1251 1252 { 1253 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL); 1254 TraceCollectorStats tcs(g1mm()->full_collection_counters()); 1255 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause()); 1256 1257 g1_policy()->record_full_collection_start(); 1258 1259 // Note: When we have a more flexible GC logging framework that 1260 // allows us to add optional attributes to a GC log record we 1261 // could consider timing and reporting how long we wait in the 1262 // following two methods. 1263 wait_while_free_regions_coming(); 1264 // If we start the compaction before the CM threads finish 1265 // scanning the root regions we might trip them over as we'll 1266 // be moving objects / updating references. So let's wait until 1267 // they are done. By telling them to abort, they should complete 1268 // early. 1269 _cm->root_regions()->abort(); 1270 _cm->root_regions()->wait_until_scan_finished(); 1271 append_secondary_free_list_if_not_empty_with_lock(); 1272 1273 gc_prologue(true); 1274 increment_total_collections(true /* full gc */); 1275 increment_old_marking_cycles_started(); 1276 1277 assert(used() == recalculate_used(), "Should be equal"); 1278 1279 verify_before_gc(); 1280 1281 check_bitmaps("Full GC Start"); 1282 pre_full_gc_dump(gc_timer); 1283 1284 #if defined(COMPILER2) || INCLUDE_JVMCI 1285 DerivedPointerTable::clear(); 1286 #endif 1287 1288 // Disable discovery and empty the discovered lists 1289 // for the CM ref processor. 1290 ref_processor_cm()->disable_discovery(); 1291 ref_processor_cm()->abandon_partial_discovery(); 1292 ref_processor_cm()->verify_no_references_recorded(); 1293 1294 // Abandon current iterations of concurrent marking and concurrent 1295 // refinement, if any are in progress. We have to do this before 1296 // wait_until_scan_finished() below. 1297 concurrent_mark()->abort(); 1298 1299 // Make sure we'll choose a new allocation region afterwards. 1300 _allocator->release_mutator_alloc_region(); 1301 _allocator->abandon_gc_alloc_regions(); 1302 g1_rem_set()->cleanupHRRS(); 1303 1304 // We should call this after we retire any currently active alloc 1305 // regions so that all the ALLOC / RETIRE events are generated 1306 // before the start GC event. 1307 _hr_printer.start_gc(true /* full */, (size_t) total_collections()); 1308 1309 // We may have added regions to the current incremental collection 1310 // set between the last GC or pause and now. We need to clear the 1311 // incremental collection set and then start rebuilding it afresh 1312 // after this full GC. 1313 abandon_collection_set(g1_policy()->inc_cset_head()); 1314 g1_policy()->clear_incremental_cset(); 1315 g1_policy()->stop_incremental_cset_building(); 1316 1317 tear_down_region_sets(false /* free_list_only */); 1318 collector_state()->set_gcs_are_young(true); 1319 1320 // See the comments in g1CollectedHeap.hpp and 1321 // G1CollectedHeap::ref_processing_init() about 1322 // how reference processing currently works in G1. 1323 1324 // Temporarily make discovery by the STW ref processor single threaded (non-MT). 1325 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false); 1326 1327 // Temporarily clear the STW ref processor's _is_alive_non_header field. 1328 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL); 1329 1330 ref_processor_stw()->enable_discovery(); 1331 ref_processor_stw()->setup_policy(do_clear_all_soft_refs); 1332 1333 // Do collection work 1334 { 1335 HandleMark hm; // Discard invalid handles created during gc 1336 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs); 1337 } 1338 1339 assert(num_free_regions() == 0, "we should not have added any free regions"); 1340 rebuild_region_sets(false /* free_list_only */); 1341 1342 // Enqueue any discovered reference objects that have 1343 // not been removed from the discovered lists. 1344 ref_processor_stw()->enqueue_discovered_references(); 1345 1346 #if defined(COMPILER2) || INCLUDE_JVMCI 1347 DerivedPointerTable::update_pointers(); 1348 #endif 1349 1350 MemoryService::track_memory_usage(); 1351 1352 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 1353 ref_processor_stw()->verify_no_references_recorded(); 1354 1355 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 1356 ClassLoaderDataGraph::purge(); 1357 MetaspaceAux::verify_metrics(); 1358 1359 // Note: since we've just done a full GC, concurrent 1360 // marking is no longer active. Therefore we need not 1361 // re-enable reference discovery for the CM ref processor. 1362 // That will be done at the start of the next marking cycle. 1363 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition"); 1364 ref_processor_cm()->verify_no_references_recorded(); 1365 1366 reset_gc_time_stamp(); 1367 // Since everything potentially moved, we will clear all remembered 1368 // sets, and clear all cards. Later we will rebuild remembered 1369 // sets. We will also reset the GC time stamps of the regions. 1370 clear_rsets_post_compaction(); 1371 check_gc_time_stamps(); 1372 1373 // Resize the heap if necessary. 1374 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size); 1375 1376 if (_hr_printer.is_active()) { 1377 // We should do this after we potentially resize the heap so 1378 // that all the COMMIT / UNCOMMIT events are generated before 1379 // the end GC event. 1380 1381 print_hrm_post_compaction(); 1382 _hr_printer.end_gc(true /* full */, (size_t) total_collections()); 1383 } 1384 1385 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 1386 if (hot_card_cache->use_cache()) { 1387 hot_card_cache->reset_card_counts(); 1388 hot_card_cache->reset_hot_cache(); 1389 } 1390 1391 // Rebuild remembered sets of all regions. 1392 uint n_workers = 1393 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 1394 workers()->active_workers(), 1395 Threads::number_of_non_daemon_threads()); 1396 workers()->set_active_workers(n_workers); 1397 1398 ParRebuildRSTask rebuild_rs_task(this); 1399 workers()->run_task(&rebuild_rs_task); 1400 1401 // Rebuild the strong code root lists for each region 1402 rebuild_strong_code_roots(); 1403 1404 if (true) { // FIXME 1405 MetaspaceGC::compute_new_size(); 1406 } 1407 1408 #ifdef TRACESPINNING 1409 ParallelTaskTerminator::print_termination_counts(); 1410 #endif 1411 1412 // Discard all rset updates 1413 JavaThread::dirty_card_queue_set().abandon_logs(); 1414 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty"); 1415 1416 _young_list->reset_sampled_info(); 1417 // At this point there should be no regions in the 1418 // entire heap tagged as young. 1419 assert(check_young_list_empty(true /* check_heap */), 1420 "young list should be empty at this point"); 1421 1422 // Update the number of full collections that have been completed. 1423 increment_old_marking_cycles_completed(false /* concurrent */); 1424 1425 _hrm.verify_optional(); 1426 verify_region_sets_optional(); 1427 1428 verify_after_gc(); 1429 1430 // Clear the previous marking bitmap, if needed for bitmap verification. 1431 // Note we cannot do this when we clear the next marking bitmap in 1432 // ConcurrentMark::abort() above since VerifyDuringGC verifies the 1433 // objects marked during a full GC against the previous bitmap. 1434 // But we need to clear it before calling check_bitmaps below since 1435 // the full GC has compacted objects and updated TAMS but not updated 1436 // the prev bitmap. 1437 if (G1VerifyBitmaps) { 1438 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll(); 1439 } 1440 check_bitmaps("Full GC End"); 1441 1442 // Start a new incremental collection set for the next pause 1443 assert(g1_policy()->collection_set() == NULL, "must be"); 1444 g1_policy()->start_incremental_cset_building(); 1445 1446 clear_cset_fast_test(); 1447 1448 _allocator->init_mutator_alloc_region(); 1449 1450 g1_policy()->record_full_collection_end(); 1451 1452 if (G1Log::fine()) { 1453 g1_policy()->print_heap_transition(); 1454 } 1455 1456 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 1457 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 1458 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 1459 // before any GC notifications are raised. 1460 g1mm()->update_sizes(); 1461 1462 gc_epilogue(true); 1463 } 1464 1465 if (G1Log::finer()) { 1466 g1_policy()->print_detailed_heap_transition(true /* full */); 1467 } 1468 1469 print_heap_after_gc(); 1470 trace_heap_after_gc(gc_tracer); 1471 1472 post_full_gc_dump(gc_timer); 1473 1474 gc_timer->register_gc_end(); 1475 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions()); 1476 } 1477 1478 return true; 1479 } 1480 1481 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) { 1482 // do_collection() will return whether it succeeded in performing 1483 // the GC. Currently, there is no facility on the 1484 // do_full_collection() API to notify the caller than the collection 1485 // did not succeed (e.g., because it was locked out by the GC 1486 // locker). So, right now, we'll ignore the return value. 1487 bool dummy = do_collection(true, /* explicit_gc */ 1488 clear_all_soft_refs, 1489 0 /* word_size */); 1490 } 1491 1492 // This code is mostly copied from TenuredGeneration. 1493 void 1494 G1CollectedHeap:: 1495 resize_if_necessary_after_full_collection(size_t word_size) { 1496 // Include the current allocation, if any, and bytes that will be 1497 // pre-allocated to support collections, as "used". 1498 const size_t used_after_gc = used(); 1499 const size_t capacity_after_gc = capacity(); 1500 const size_t free_after_gc = capacity_after_gc - used_after_gc; 1501 1502 // This is enforced in arguments.cpp. 1503 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, 1504 "otherwise the code below doesn't make sense"); 1505 1506 // We don't have floating point command-line arguments 1507 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0; 1508 const double maximum_used_percentage = 1.0 - minimum_free_percentage; 1509 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0; 1510 const double minimum_used_percentage = 1.0 - maximum_free_percentage; 1511 1512 const size_t min_heap_size = collector_policy()->min_heap_byte_size(); 1513 const size_t max_heap_size = collector_policy()->max_heap_byte_size(); 1514 1515 // We have to be careful here as these two calculations can overflow 1516 // 32-bit size_t's. 1517 double used_after_gc_d = (double) used_after_gc; 1518 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage; 1519 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage; 1520 1521 // Let's make sure that they are both under the max heap size, which 1522 // by default will make them fit into a size_t. 1523 double desired_capacity_upper_bound = (double) max_heap_size; 1524 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d, 1525 desired_capacity_upper_bound); 1526 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d, 1527 desired_capacity_upper_bound); 1528 1529 // We can now safely turn them into size_t's. 1530 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d; 1531 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d; 1532 1533 // This assert only makes sense here, before we adjust them 1534 // with respect to the min and max heap size. 1535 assert(minimum_desired_capacity <= maximum_desired_capacity, 1536 "minimum_desired_capacity = " SIZE_FORMAT ", " 1537 "maximum_desired_capacity = " SIZE_FORMAT, 1538 minimum_desired_capacity, maximum_desired_capacity); 1539 1540 // Should not be greater than the heap max size. No need to adjust 1541 // it with respect to the heap min size as it's a lower bound (i.e., 1542 // we'll try to make the capacity larger than it, not smaller). 1543 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size); 1544 // Should not be less than the heap min size. No need to adjust it 1545 // with respect to the heap max size as it's an upper bound (i.e., 1546 // we'll try to make the capacity smaller than it, not greater). 1547 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size); 1548 1549 if (capacity_after_gc < minimum_desired_capacity) { 1550 // Don't expand unless it's significant 1551 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc; 1552 ergo_verbose4(ErgoHeapSizing, 1553 "attempt heap expansion", 1554 ergo_format_reason("capacity lower than " 1555 "min desired capacity after Full GC") 1556 ergo_format_byte("capacity") 1557 ergo_format_byte("occupancy") 1558 ergo_format_byte_perc("min desired capacity"), 1559 capacity_after_gc, used_after_gc, 1560 minimum_desired_capacity, (double) MinHeapFreeRatio); 1561 expand(expand_bytes); 1562 1563 // No expansion, now see if we want to shrink 1564 } else if (capacity_after_gc > maximum_desired_capacity) { 1565 // Capacity too large, compute shrinking size 1566 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity; 1567 ergo_verbose4(ErgoHeapSizing, 1568 "attempt heap shrinking", 1569 ergo_format_reason("capacity higher than " 1570 "max desired capacity after Full GC") 1571 ergo_format_byte("capacity") 1572 ergo_format_byte("occupancy") 1573 ergo_format_byte_perc("max desired capacity"), 1574 capacity_after_gc, used_after_gc, 1575 maximum_desired_capacity, (double) MaxHeapFreeRatio); 1576 shrink(shrink_bytes); 1577 } 1578 } 1579 1580 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size, 1581 AllocationContext_t context, 1582 bool do_gc, 1583 bool clear_all_soft_refs, 1584 bool expect_null_mutator_alloc_region, 1585 bool* gc_succeeded) { 1586 *gc_succeeded = true; 1587 // Let's attempt the allocation first. 1588 HeapWord* result = 1589 attempt_allocation_at_safepoint(word_size, 1590 context, 1591 expect_null_mutator_alloc_region); 1592 if (result != NULL) { 1593 assert(*gc_succeeded, "sanity"); 1594 return result; 1595 } 1596 1597 // In a G1 heap, we're supposed to keep allocation from failing by 1598 // incremental pauses. Therefore, at least for now, we'll favor 1599 // expansion over collection. (This might change in the future if we can 1600 // do something smarter than full collection to satisfy a failed alloc.) 1601 result = expand_and_allocate(word_size, context); 1602 if (result != NULL) { 1603 assert(*gc_succeeded, "sanity"); 1604 return result; 1605 } 1606 1607 if (do_gc) { 1608 // Expansion didn't work, we'll try to do a Full GC. 1609 *gc_succeeded = do_collection(false, /* explicit_gc */ 1610 clear_all_soft_refs, 1611 word_size); 1612 } 1613 1614 return NULL; 1615 } 1616 1617 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size, 1618 AllocationContext_t context, 1619 bool* succeeded) { 1620 assert_at_safepoint(true /* should_be_vm_thread */); 1621 1622 // Attempts to allocate followed by Full GC. 1623 HeapWord* result = 1624 satisfy_failed_allocation_helper(word_size, 1625 context, 1626 true, /* do_gc */ 1627 false, /* clear_all_soft_refs */ 1628 false, /* expect_null_mutator_alloc_region */ 1629 succeeded); 1630 1631 if (result != NULL || !*succeeded) { 1632 return result; 1633 } 1634 1635 // Attempts to allocate followed by Full GC that will collect all soft references. 1636 result = satisfy_failed_allocation_helper(word_size, 1637 context, 1638 true, /* do_gc */ 1639 true, /* clear_all_soft_refs */ 1640 true, /* expect_null_mutator_alloc_region */ 1641 succeeded); 1642 1643 if (result != NULL || !*succeeded) { 1644 return result; 1645 } 1646 1647 // Attempts to allocate, no GC 1648 result = satisfy_failed_allocation_helper(word_size, 1649 context, 1650 false, /* do_gc */ 1651 false, /* clear_all_soft_refs */ 1652 true, /* expect_null_mutator_alloc_region */ 1653 succeeded); 1654 1655 if (result != NULL) { 1656 assert(*succeeded, "sanity"); 1657 return result; 1658 } 1659 1660 assert(!collector_policy()->should_clear_all_soft_refs(), 1661 "Flag should have been handled and cleared prior to this point"); 1662 1663 // What else? We might try synchronous finalization later. If the total 1664 // space available is large enough for the allocation, then a more 1665 // complete compaction phase than we've tried so far might be 1666 // appropriate. 1667 assert(*succeeded, "sanity"); 1668 return NULL; 1669 } 1670 1671 // Attempting to expand the heap sufficiently 1672 // to support an allocation of the given "word_size". If 1673 // successful, perform the allocation and return the address of the 1674 // allocated block, or else "NULL". 1675 1676 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) { 1677 assert_at_safepoint(true /* should_be_vm_thread */); 1678 1679 verify_region_sets_optional(); 1680 1681 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes); 1682 ergo_verbose1(ErgoHeapSizing, 1683 "attempt heap expansion", 1684 ergo_format_reason("allocation request failed") 1685 ergo_format_byte("allocation request"), 1686 word_size * HeapWordSize); 1687 if (expand(expand_bytes)) { 1688 _hrm.verify_optional(); 1689 verify_region_sets_optional(); 1690 return attempt_allocation_at_safepoint(word_size, 1691 context, 1692 false /* expect_null_mutator_alloc_region */); 1693 } 1694 return NULL; 1695 } 1696 1697 bool G1CollectedHeap::expand(size_t expand_bytes, double* expand_time_ms) { 1698 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); 1699 aligned_expand_bytes = align_size_up(aligned_expand_bytes, 1700 HeapRegion::GrainBytes); 1701 ergo_verbose2(ErgoHeapSizing, 1702 "expand the heap", 1703 ergo_format_byte("requested expansion amount") 1704 ergo_format_byte("attempted expansion amount"), 1705 expand_bytes, aligned_expand_bytes); 1706 1707 if (is_maximal_no_gc()) { 1708 ergo_verbose0(ErgoHeapSizing, 1709 "did not expand the heap", 1710 ergo_format_reason("heap already fully expanded")); 1711 return false; 1712 } 1713 1714 double expand_heap_start_time_sec = os::elapsedTime(); 1715 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes); 1716 assert(regions_to_expand > 0, "Must expand by at least one region"); 1717 1718 uint expanded_by = _hrm.expand_by(regions_to_expand); 1719 if (expand_time_ms != NULL) { 1720 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS; 1721 } 1722 1723 if (expanded_by > 0) { 1724 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes; 1725 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition"); 1726 g1_policy()->record_new_heap_size(num_regions()); 1727 } else { 1728 ergo_verbose0(ErgoHeapSizing, 1729 "did not expand the heap", 1730 ergo_format_reason("heap expansion operation failed")); 1731 // The expansion of the virtual storage space was unsuccessful. 1732 // Let's see if it was because we ran out of swap. 1733 if (G1ExitOnExpansionFailure && 1734 _hrm.available() >= regions_to_expand) { 1735 // We had head room... 1736 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion"); 1737 } 1738 } 1739 return regions_to_expand > 0; 1740 } 1741 1742 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) { 1743 size_t aligned_shrink_bytes = 1744 ReservedSpace::page_align_size_down(shrink_bytes); 1745 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes, 1746 HeapRegion::GrainBytes); 1747 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes); 1748 1749 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove); 1750 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes; 1751 1752 ergo_verbose3(ErgoHeapSizing, 1753 "shrink the heap", 1754 ergo_format_byte("requested shrinking amount") 1755 ergo_format_byte("aligned shrinking amount") 1756 ergo_format_byte("attempted shrinking amount"), 1757 shrink_bytes, aligned_shrink_bytes, shrunk_bytes); 1758 if (num_regions_removed > 0) { 1759 g1_policy()->record_new_heap_size(num_regions()); 1760 } else { 1761 ergo_verbose0(ErgoHeapSizing, 1762 "did not shrink the heap", 1763 ergo_format_reason("heap shrinking operation failed")); 1764 } 1765 } 1766 1767 void G1CollectedHeap::shrink(size_t shrink_bytes) { 1768 verify_region_sets_optional(); 1769 1770 // We should only reach here at the end of a Full GC which means we 1771 // should not not be holding to any GC alloc regions. The method 1772 // below will make sure of that and do any remaining clean up. 1773 _allocator->abandon_gc_alloc_regions(); 1774 1775 // Instead of tearing down / rebuilding the free lists here, we 1776 // could instead use the remove_all_pending() method on free_list to 1777 // remove only the ones that we need to remove. 1778 tear_down_region_sets(true /* free_list_only */); 1779 shrink_helper(shrink_bytes); 1780 rebuild_region_sets(true /* free_list_only */); 1781 1782 _hrm.verify_optional(); 1783 verify_region_sets_optional(); 1784 } 1785 1786 // Public methods. 1787 1788 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away 1789 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list 1790 #endif // _MSC_VER 1791 1792 1793 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) : 1794 CollectedHeap(), 1795 _g1_policy(policy_), 1796 _dirty_card_queue_set(false), 1797 _into_cset_dirty_card_queue_set(false), 1798 _is_alive_closure_cm(this), 1799 _is_alive_closure_stw(this), 1800 _ref_processor_cm(NULL), 1801 _ref_processor_stw(NULL), 1802 _bot_shared(NULL), 1803 _cg1r(NULL), 1804 _g1mm(NULL), 1805 _refine_cte_cl(NULL), 1806 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()), 1807 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()), 1808 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()), 1809 _humongous_reclaim_candidates(), 1810 _has_humongous_reclaim_candidates(false), 1811 _archive_allocator(NULL), 1812 _free_regions_coming(false), 1813 _young_list(new YoungList(this)), 1814 _gc_time_stamp(0), 1815 _summary_bytes_used(0), 1816 _survivor_evac_stats(YoungPLABSize, PLABWeight), 1817 _old_evac_stats(OldPLABSize, PLABWeight), 1818 _expand_heap_after_alloc_failure(true), 1819 _old_marking_cycles_started(0), 1820 _old_marking_cycles_completed(0), 1821 _heap_summary_sent(false), 1822 _in_cset_fast_test(), 1823 _dirty_cards_region_list(NULL), 1824 _worker_cset_start_region(NULL), 1825 _worker_cset_start_region_time_stamp(NULL), 1826 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()), 1827 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()), 1828 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()), 1829 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) { 1830 1831 _workers = new WorkGang("GC Thread", ParallelGCThreads, 1832 /* are_GC_task_threads */true, 1833 /* are_ConcurrentGC_threads */false); 1834 _workers->initialize_workers(); 1835 1836 _allocator = G1Allocator::create_allocator(this); 1837 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords); 1838 1839 // Override the default _filler_array_max_size so that no humongous filler 1840 // objects are created. 1841 _filler_array_max_size = _humongous_object_threshold_in_words; 1842 1843 uint n_queues = ParallelGCThreads; 1844 _task_queues = new RefToScanQueueSet(n_queues); 1845 1846 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets(); 1847 assert(n_rem_sets > 0, "Invariant."); 1848 1849 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC); 1850 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC); 1851 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC); 1852 1853 for (uint i = 0; i < n_queues; i++) { 1854 RefToScanQueue* q = new RefToScanQueue(); 1855 q->initialize(); 1856 _task_queues->register_queue(i, q); 1857 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo(); 1858 } 1859 clear_cset_start_regions(); 1860 1861 // Initialize the G1EvacuationFailureALot counters and flags. 1862 NOT_PRODUCT(reset_evacuation_should_fail();) 1863 1864 guarantee(_task_queues != NULL, "task_queues allocation failure."); 1865 } 1866 1867 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description, 1868 size_t size, 1869 size_t translation_factor) { 1870 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1); 1871 // Allocate a new reserved space, preferring to use large pages. 1872 ReservedSpace rs(size, preferred_page_size); 1873 G1RegionToSpaceMapper* result = 1874 G1RegionToSpaceMapper::create_mapper(rs, 1875 size, 1876 rs.alignment(), 1877 HeapRegion::GrainBytes, 1878 translation_factor, 1879 mtGC); 1880 if (TracePageSizes) { 1881 gclog_or_tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT, 1882 description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size); 1883 } 1884 return result; 1885 } 1886 1887 jint G1CollectedHeap::initialize() { 1888 CollectedHeap::pre_initialize(); 1889 os::enable_vtime(); 1890 1891 G1Log::init(); 1892 1893 // Necessary to satisfy locking discipline assertions. 1894 1895 MutexLocker x(Heap_lock); 1896 1897 // We have to initialize the printer before committing the heap, as 1898 // it will be used then. 1899 _hr_printer.set_active(G1PrintHeapRegions); 1900 1901 // While there are no constraints in the GC code that HeapWordSize 1902 // be any particular value, there are multiple other areas in the 1903 // system which believe this to be true (e.g. oop->object_size in some 1904 // cases incorrectly returns the size in wordSize units rather than 1905 // HeapWordSize). 1906 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 1907 1908 size_t init_byte_size = collector_policy()->initial_heap_byte_size(); 1909 size_t max_byte_size = collector_policy()->max_heap_byte_size(); 1910 size_t heap_alignment = collector_policy()->heap_alignment(); 1911 1912 // Ensure that the sizes are properly aligned. 1913 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1914 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1915 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap"); 1916 1917 _refine_cte_cl = new RefineCardTableEntryClosure(); 1918 1919 jint ecode = JNI_OK; 1920 _cg1r = ConcurrentG1Refine::create(this, _refine_cte_cl, &ecode); 1921 if (_cg1r == NULL) { 1922 return ecode; 1923 } 1924 1925 // Reserve the maximum. 1926 1927 // When compressed oops are enabled, the preferred heap base 1928 // is calculated by subtracting the requested size from the 1929 // 32Gb boundary and using the result as the base address for 1930 // heap reservation. If the requested size is not aligned to 1931 // HeapRegion::GrainBytes (i.e. the alignment that is passed 1932 // into the ReservedHeapSpace constructor) then the actual 1933 // base of the reserved heap may end up differing from the 1934 // address that was requested (i.e. the preferred heap base). 1935 // If this happens then we could end up using a non-optimal 1936 // compressed oops mode. 1937 1938 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size, 1939 heap_alignment); 1940 1941 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size())); 1942 1943 // Create the barrier set for the entire reserved region. 1944 G1SATBCardTableLoggingModRefBS* bs 1945 = new G1SATBCardTableLoggingModRefBS(reserved_region()); 1946 bs->initialize(); 1947 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity"); 1948 set_barrier_set(bs); 1949 1950 // Also create a G1 rem set. 1951 _g1_rem_set = new G1RemSet(this, g1_barrier_set()); 1952 1953 // Carve out the G1 part of the heap. 1954 1955 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size); 1956 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size(); 1957 G1RegionToSpaceMapper* heap_storage = 1958 G1RegionToSpaceMapper::create_mapper(g1_rs, 1959 g1_rs.size(), 1960 page_size, 1961 HeapRegion::GrainBytes, 1962 1, 1963 mtJavaHeap); 1964 os::trace_page_sizes("G1 Heap", collector_policy()->min_heap_byte_size(), 1965 max_byte_size, page_size, 1966 heap_rs.base(), 1967 heap_rs.size()); 1968 heap_storage->set_mapping_changed_listener(&_listener); 1969 1970 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps. 1971 G1RegionToSpaceMapper* bot_storage = 1972 create_aux_memory_mapper("Block offset table", 1973 G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize), 1974 G1BlockOffsetSharedArray::heap_map_factor()); 1975 1976 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize)); 1977 G1RegionToSpaceMapper* cardtable_storage = 1978 create_aux_memory_mapper("Card table", 1979 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize), 1980 G1SATBCardTableLoggingModRefBS::heap_map_factor()); 1981 1982 G1RegionToSpaceMapper* card_counts_storage = 1983 create_aux_memory_mapper("Card counts table", 1984 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize), 1985 G1CardCounts::heap_map_factor()); 1986 1987 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size()); 1988 G1RegionToSpaceMapper* prev_bitmap_storage = 1989 create_aux_memory_mapper("Prev Bitmap", bitmap_size, CMBitMap::heap_map_factor()); 1990 G1RegionToSpaceMapper* next_bitmap_storage = 1991 create_aux_memory_mapper("Next Bitmap", bitmap_size, CMBitMap::heap_map_factor()); 1992 1993 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage); 1994 g1_barrier_set()->initialize(cardtable_storage); 1995 // Do later initialization work for concurrent refinement. 1996 _cg1r->init(card_counts_storage); 1997 1998 // 6843694 - ensure that the maximum region index can fit 1999 // in the remembered set structures. 2000 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; 2001 guarantee((max_regions() - 1) <= max_region_idx, "too many regions"); 2002 2003 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; 2004 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); 2005 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region, 2006 "too many cards per region"); 2007 2008 FreeRegionList::set_unrealistically_long_length(max_regions() + 1); 2009 2010 _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage); 2011 2012 { 2013 HeapWord* start = _hrm.reserved().start(); 2014 HeapWord* end = _hrm.reserved().end(); 2015 size_t granularity = HeapRegion::GrainBytes; 2016 2017 _in_cset_fast_test.initialize(start, end, granularity); 2018 _humongous_reclaim_candidates.initialize(start, end, granularity); 2019 } 2020 2021 // Create the ConcurrentMark data structure and thread. 2022 // (Must do this late, so that "max_regions" is defined.) 2023 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage); 2024 if (_cm == NULL || !_cm->completed_initialization()) { 2025 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark"); 2026 return JNI_ENOMEM; 2027 } 2028 _cmThread = _cm->cmThread(); 2029 2030 // Initialize the from_card cache structure of HeapRegionRemSet. 2031 HeapRegionRemSet::init_heap(max_regions()); 2032 2033 // Now expand into the initial heap size. 2034 if (!expand(init_byte_size)) { 2035 vm_shutdown_during_initialization("Failed to allocate initial heap."); 2036 return JNI_ENOMEM; 2037 } 2038 2039 // Perform any initialization actions delegated to the policy. 2040 g1_policy()->init(); 2041 2042 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon, 2043 SATB_Q_FL_lock, 2044 G1SATBProcessCompletedThreshold, 2045 Shared_SATB_Q_lock); 2046 2047 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl, 2048 DirtyCardQ_CBL_mon, 2049 DirtyCardQ_FL_lock, 2050 concurrent_g1_refine()->yellow_zone(), 2051 concurrent_g1_refine()->red_zone(), 2052 Shared_DirtyCardQ_lock); 2053 2054 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code 2055 DirtyCardQ_CBL_mon, 2056 DirtyCardQ_FL_lock, 2057 -1, // never trigger processing 2058 -1, // no limit on length 2059 Shared_DirtyCardQ_lock, 2060 &JavaThread::dirty_card_queue_set()); 2061 2062 // Initialize the card queue set used to hold cards containing 2063 // references into the collection set. 2064 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code 2065 DirtyCardQ_CBL_mon, 2066 DirtyCardQ_FL_lock, 2067 -1, // never trigger processing 2068 -1, // no limit on length 2069 Shared_DirtyCardQ_lock, 2070 &JavaThread::dirty_card_queue_set()); 2071 2072 // Here we allocate the dummy HeapRegion that is required by the 2073 // G1AllocRegion class. 2074 HeapRegion* dummy_region = _hrm.get_dummy_region(); 2075 2076 // We'll re-use the same region whether the alloc region will 2077 // require BOT updates or not and, if it doesn't, then a non-young 2078 // region will complain that it cannot support allocations without 2079 // BOT updates. So we'll tag the dummy region as eden to avoid that. 2080 dummy_region->set_eden(); 2081 // Make sure it's full. 2082 dummy_region->set_top(dummy_region->end()); 2083 G1AllocRegion::setup(this, dummy_region); 2084 2085 _allocator->init_mutator_alloc_region(); 2086 2087 // Do create of the monitoring and management support so that 2088 // values in the heap have been properly initialized. 2089 _g1mm = new G1MonitoringSupport(this); 2090 2091 G1StringDedup::initialize(); 2092 2093 _preserved_objs = NEW_C_HEAP_ARRAY(OopAndMarkOopStack, ParallelGCThreads, mtGC); 2094 for (uint i = 0; i < ParallelGCThreads; i++) { 2095 new (&_preserved_objs[i]) OopAndMarkOopStack(); 2096 } 2097 2098 return JNI_OK; 2099 } 2100 2101 void G1CollectedHeap::stop() { 2102 // Stop all concurrent threads. We do this to make sure these threads 2103 // do not continue to execute and access resources (e.g. gclog_or_tty) 2104 // that are destroyed during shutdown. 2105 _cg1r->stop(); 2106 _cmThread->stop(); 2107 if (G1StringDedup::is_enabled()) { 2108 G1StringDedup::stop(); 2109 } 2110 } 2111 2112 size_t G1CollectedHeap::conservative_max_heap_alignment() { 2113 return HeapRegion::max_region_size(); 2114 } 2115 2116 void G1CollectedHeap::post_initialize() { 2117 CollectedHeap::post_initialize(); 2118 ref_processing_init(); 2119 } 2120 2121 void G1CollectedHeap::ref_processing_init() { 2122 // Reference processing in G1 currently works as follows: 2123 // 2124 // * There are two reference processor instances. One is 2125 // used to record and process discovered references 2126 // during concurrent marking; the other is used to 2127 // record and process references during STW pauses 2128 // (both full and incremental). 2129 // * Both ref processors need to 'span' the entire heap as 2130 // the regions in the collection set may be dotted around. 2131 // 2132 // * For the concurrent marking ref processor: 2133 // * Reference discovery is enabled at initial marking. 2134 // * Reference discovery is disabled and the discovered 2135 // references processed etc during remarking. 2136 // * Reference discovery is MT (see below). 2137 // * Reference discovery requires a barrier (see below). 2138 // * Reference processing may or may not be MT 2139 // (depending on the value of ParallelRefProcEnabled 2140 // and ParallelGCThreads). 2141 // * A full GC disables reference discovery by the CM 2142 // ref processor and abandons any entries on it's 2143 // discovered lists. 2144 // 2145 // * For the STW processor: 2146 // * Non MT discovery is enabled at the start of a full GC. 2147 // * Processing and enqueueing during a full GC is non-MT. 2148 // * During a full GC, references are processed after marking. 2149 // 2150 // * Discovery (may or may not be MT) is enabled at the start 2151 // of an incremental evacuation pause. 2152 // * References are processed near the end of a STW evacuation pause. 2153 // * For both types of GC: 2154 // * Discovery is atomic - i.e. not concurrent. 2155 // * Reference discovery will not need a barrier. 2156 2157 MemRegion mr = reserved_region(); 2158 2159 // Concurrent Mark ref processor 2160 _ref_processor_cm = 2161 new ReferenceProcessor(mr, // span 2162 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2163 // mt processing 2164 ParallelGCThreads, 2165 // degree of mt processing 2166 (ParallelGCThreads > 1) || (ConcGCThreads > 1), 2167 // mt discovery 2168 MAX2(ParallelGCThreads, ConcGCThreads), 2169 // degree of mt discovery 2170 false, 2171 // Reference discovery is not atomic 2172 &_is_alive_closure_cm); 2173 // is alive closure 2174 // (for efficiency/performance) 2175 2176 // STW ref processor 2177 _ref_processor_stw = 2178 new ReferenceProcessor(mr, // span 2179 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2180 // mt processing 2181 ParallelGCThreads, 2182 // degree of mt processing 2183 (ParallelGCThreads > 1), 2184 // mt discovery 2185 ParallelGCThreads, 2186 // degree of mt discovery 2187 true, 2188 // Reference discovery is atomic 2189 &_is_alive_closure_stw); 2190 // is alive closure 2191 // (for efficiency/performance) 2192 } 2193 2194 CollectorPolicy* G1CollectedHeap::collector_policy() const { 2195 return g1_policy(); 2196 } 2197 2198 size_t G1CollectedHeap::capacity() const { 2199 return _hrm.length() * HeapRegion::GrainBytes; 2200 } 2201 2202 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) { 2203 hr->reset_gc_time_stamp(); 2204 } 2205 2206 #ifndef PRODUCT 2207 2208 class CheckGCTimeStampsHRClosure : public HeapRegionClosure { 2209 private: 2210 unsigned _gc_time_stamp; 2211 bool _failures; 2212 2213 public: 2214 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) : 2215 _gc_time_stamp(gc_time_stamp), _failures(false) { } 2216 2217 virtual bool doHeapRegion(HeapRegion* hr) { 2218 unsigned region_gc_time_stamp = hr->get_gc_time_stamp(); 2219 if (_gc_time_stamp != region_gc_time_stamp) { 2220 gclog_or_tty->print_cr("Region " HR_FORMAT " has GC time stamp = %d, " 2221 "expected %d", HR_FORMAT_PARAMS(hr), 2222 region_gc_time_stamp, _gc_time_stamp); 2223 _failures = true; 2224 } 2225 return false; 2226 } 2227 2228 bool failures() { return _failures; } 2229 }; 2230 2231 void G1CollectedHeap::check_gc_time_stamps() { 2232 CheckGCTimeStampsHRClosure cl(_gc_time_stamp); 2233 heap_region_iterate(&cl); 2234 guarantee(!cl.failures(), "all GC time stamps should have been reset"); 2235 } 2236 #endif // PRODUCT 2237 2238 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) { 2239 _cg1r->hot_card_cache()->drain(cl, worker_i); 2240 } 2241 2242 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) { 2243 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 2244 size_t n_completed_buffers = 0; 2245 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) { 2246 n_completed_buffers++; 2247 } 2248 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers); 2249 dcqs.clear_n_completed_buffers(); 2250 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!"); 2251 } 2252 2253 // Computes the sum of the storage used by the various regions. 2254 size_t G1CollectedHeap::used() const { 2255 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions(); 2256 if (_archive_allocator != NULL) { 2257 result += _archive_allocator->used(); 2258 } 2259 return result; 2260 } 2261 2262 size_t G1CollectedHeap::used_unlocked() const { 2263 return _summary_bytes_used; 2264 } 2265 2266 class SumUsedClosure: public HeapRegionClosure { 2267 size_t _used; 2268 public: 2269 SumUsedClosure() : _used(0) {} 2270 bool doHeapRegion(HeapRegion* r) { 2271 _used += r->used(); 2272 return false; 2273 } 2274 size_t result() { return _used; } 2275 }; 2276 2277 size_t G1CollectedHeap::recalculate_used() const { 2278 double recalculate_used_start = os::elapsedTime(); 2279 2280 SumUsedClosure blk; 2281 heap_region_iterate(&blk); 2282 2283 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0); 2284 return blk.result(); 2285 } 2286 2287 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 2288 switch (cause) { 2289 case GCCause::_gc_locker: return GCLockerInvokesConcurrent; 2290 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent; 2291 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent; 2292 case GCCause::_g1_humongous_allocation: return true; 2293 case GCCause::_update_allocation_context_stats_inc: return true; 2294 case GCCause::_wb_conc_mark: return true; 2295 default: return false; 2296 } 2297 } 2298 2299 #ifndef PRODUCT 2300 void G1CollectedHeap::allocate_dummy_regions() { 2301 // Let's fill up most of the region 2302 size_t word_size = HeapRegion::GrainWords - 1024; 2303 // And as a result the region we'll allocate will be humongous. 2304 guarantee(is_humongous(word_size), "sanity"); 2305 2306 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) { 2307 // Let's use the existing mechanism for the allocation 2308 HeapWord* dummy_obj = humongous_obj_allocate(word_size, 2309 AllocationContext::system()); 2310 if (dummy_obj != NULL) { 2311 MemRegion mr(dummy_obj, word_size); 2312 CollectedHeap::fill_with_object(mr); 2313 } else { 2314 // If we can't allocate once, we probably cannot allocate 2315 // again. Let's get out of the loop. 2316 break; 2317 } 2318 } 2319 } 2320 #endif // !PRODUCT 2321 2322 void G1CollectedHeap::increment_old_marking_cycles_started() { 2323 assert(_old_marking_cycles_started == _old_marking_cycles_completed || 2324 _old_marking_cycles_started == _old_marking_cycles_completed + 1, 2325 "Wrong marking cycle count (started: %d, completed: %d)", 2326 _old_marking_cycles_started, _old_marking_cycles_completed); 2327 2328 _old_marking_cycles_started++; 2329 } 2330 2331 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) { 2332 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 2333 2334 // We assume that if concurrent == true, then the caller is a 2335 // concurrent thread that was joined the Suspendible Thread 2336 // Set. If there's ever a cheap way to check this, we should add an 2337 // assert here. 2338 2339 // Given that this method is called at the end of a Full GC or of a 2340 // concurrent cycle, and those can be nested (i.e., a Full GC can 2341 // interrupt a concurrent cycle), the number of full collections 2342 // completed should be either one (in the case where there was no 2343 // nesting) or two (when a Full GC interrupted a concurrent cycle) 2344 // behind the number of full collections started. 2345 2346 // This is the case for the inner caller, i.e. a Full GC. 2347 assert(concurrent || 2348 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || 2349 (_old_marking_cycles_started == _old_marking_cycles_completed + 2), 2350 "for inner caller (Full GC): _old_marking_cycles_started = %u " 2351 "is inconsistent with _old_marking_cycles_completed = %u", 2352 _old_marking_cycles_started, _old_marking_cycles_completed); 2353 2354 // This is the case for the outer caller, i.e. the concurrent cycle. 2355 assert(!concurrent || 2356 (_old_marking_cycles_started == _old_marking_cycles_completed + 1), 2357 "for outer caller (concurrent cycle): " 2358 "_old_marking_cycles_started = %u " 2359 "is inconsistent with _old_marking_cycles_completed = %u", 2360 _old_marking_cycles_started, _old_marking_cycles_completed); 2361 2362 _old_marking_cycles_completed += 1; 2363 2364 // We need to clear the "in_progress" flag in the CM thread before 2365 // we wake up any waiters (especially when ExplicitInvokesConcurrent 2366 // is set) so that if a waiter requests another System.gc() it doesn't 2367 // incorrectly see that a marking cycle is still in progress. 2368 if (concurrent) { 2369 _cmThread->set_idle(); 2370 } 2371 2372 // This notify_all() will ensure that a thread that called 2373 // System.gc() with (with ExplicitGCInvokesConcurrent set or not) 2374 // and it's waiting for a full GC to finish will be woken up. It is 2375 // waiting in VM_G1IncCollectionPause::doit_epilogue(). 2376 FullGCCount_lock->notify_all(); 2377 } 2378 2379 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) { 2380 GCIdMarkAndRestore conc_gc_id_mark; 2381 collector_state()->set_concurrent_cycle_started(true); 2382 _gc_timer_cm->register_gc_start(start_time); 2383 2384 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start()); 2385 trace_heap_before_gc(_gc_tracer_cm); 2386 _cmThread->set_gc_id(GCId::current()); 2387 } 2388 2389 void G1CollectedHeap::register_concurrent_cycle_end() { 2390 if (collector_state()->concurrent_cycle_started()) { 2391 GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id()); 2392 if (_cm->has_aborted()) { 2393 _gc_tracer_cm->report_concurrent_mode_failure(); 2394 } 2395 2396 _gc_timer_cm->register_gc_end(); 2397 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions()); 2398 2399 // Clear state variables to prepare for the next concurrent cycle. 2400 collector_state()->set_concurrent_cycle_started(false); 2401 _heap_summary_sent = false; 2402 } 2403 } 2404 2405 void G1CollectedHeap::trace_heap_after_concurrent_cycle() { 2406 if (collector_state()->concurrent_cycle_started()) { 2407 // This function can be called when: 2408 // the cleanup pause is run 2409 // the concurrent cycle is aborted before the cleanup pause. 2410 // the concurrent cycle is aborted after the cleanup pause, 2411 // but before the concurrent cycle end has been registered. 2412 // Make sure that we only send the heap information once. 2413 if (!_heap_summary_sent) { 2414 GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id()); 2415 trace_heap_after_gc(_gc_tracer_cm); 2416 _heap_summary_sent = true; 2417 } 2418 } 2419 } 2420 2421 void G1CollectedHeap::collect(GCCause::Cause cause) { 2422 assert_heap_not_locked(); 2423 2424 uint gc_count_before; 2425 uint old_marking_count_before; 2426 uint full_gc_count_before; 2427 bool retry_gc; 2428 2429 do { 2430 retry_gc = false; 2431 2432 { 2433 MutexLocker ml(Heap_lock); 2434 2435 // Read the GC count while holding the Heap_lock 2436 gc_count_before = total_collections(); 2437 full_gc_count_before = total_full_collections(); 2438 old_marking_count_before = _old_marking_cycles_started; 2439 } 2440 2441 if (should_do_concurrent_full_gc(cause)) { 2442 // Schedule an initial-mark evacuation pause that will start a 2443 // concurrent cycle. We're setting word_size to 0 which means that 2444 // we are not requesting a post-GC allocation. 2445 VM_G1IncCollectionPause op(gc_count_before, 2446 0, /* word_size */ 2447 true, /* should_initiate_conc_mark */ 2448 g1_policy()->max_pause_time_ms(), 2449 cause); 2450 op.set_allocation_context(AllocationContext::current()); 2451 2452 VMThread::execute(&op); 2453 if (!op.pause_succeeded()) { 2454 if (old_marking_count_before == _old_marking_cycles_started) { 2455 retry_gc = op.should_retry_gc(); 2456 } else { 2457 // A Full GC happened while we were trying to schedule the 2458 // initial-mark GC. No point in starting a new cycle given 2459 // that the whole heap was collected anyway. 2460 } 2461 2462 if (retry_gc) { 2463 if (GC_locker::is_active_and_needs_gc()) { 2464 GC_locker::stall_until_clear(); 2465 } 2466 } 2467 } 2468 } else { 2469 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc 2470 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { 2471 2472 // Schedule a standard evacuation pause. We're setting word_size 2473 // to 0 which means that we are not requesting a post-GC allocation. 2474 VM_G1IncCollectionPause op(gc_count_before, 2475 0, /* word_size */ 2476 false, /* should_initiate_conc_mark */ 2477 g1_policy()->max_pause_time_ms(), 2478 cause); 2479 VMThread::execute(&op); 2480 } else { 2481 // Schedule a Full GC. 2482 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause); 2483 VMThread::execute(&op); 2484 } 2485 } 2486 } while (retry_gc); 2487 } 2488 2489 bool G1CollectedHeap::is_in(const void* p) const { 2490 if (_hrm.reserved().contains(p)) { 2491 // Given that we know that p is in the reserved space, 2492 // heap_region_containing() should successfully 2493 // return the containing region. 2494 HeapRegion* hr = heap_region_containing(p); 2495 return hr->is_in(p); 2496 } else { 2497 return false; 2498 } 2499 } 2500 2501 #ifdef ASSERT 2502 bool G1CollectedHeap::is_in_exact(const void* p) const { 2503 bool contains = reserved_region().contains(p); 2504 bool available = _hrm.is_available(addr_to_region((HeapWord*)p)); 2505 if (contains && available) { 2506 return true; 2507 } else { 2508 return false; 2509 } 2510 } 2511 #endif 2512 2513 bool G1CollectedHeap::obj_in_cs(oop obj) { 2514 HeapRegion* r = _hrm.addr_to_region((HeapWord*) obj); 2515 return r != NULL && r->in_collection_set(); 2516 } 2517 2518 // Iteration functions. 2519 2520 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion. 2521 2522 class IterateOopClosureRegionClosure: public HeapRegionClosure { 2523 ExtendedOopClosure* _cl; 2524 public: 2525 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {} 2526 bool doHeapRegion(HeapRegion* r) { 2527 if (!r->is_continues_humongous()) { 2528 r->oop_iterate(_cl); 2529 } 2530 return false; 2531 } 2532 }; 2533 2534 // Iterates an ObjectClosure over all objects within a HeapRegion. 2535 2536 class IterateObjectClosureRegionClosure: public HeapRegionClosure { 2537 ObjectClosure* _cl; 2538 public: 2539 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} 2540 bool doHeapRegion(HeapRegion* r) { 2541 if (!r->is_continues_humongous()) { 2542 r->object_iterate(_cl); 2543 } 2544 return false; 2545 } 2546 }; 2547 2548 void G1CollectedHeap::object_iterate(ObjectClosure* cl) { 2549 IterateObjectClosureRegionClosure blk(cl); 2550 heap_region_iterate(&blk); 2551 } 2552 2553 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { 2554 _hrm.iterate(cl); 2555 } 2556 2557 void 2558 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl, 2559 uint worker_id, 2560 HeapRegionClaimer *hrclaimer, 2561 bool concurrent) const { 2562 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent); 2563 } 2564 2565 // Clear the cached CSet starting regions and (more importantly) 2566 // the time stamps. Called when we reset the GC time stamp. 2567 void G1CollectedHeap::clear_cset_start_regions() { 2568 assert(_worker_cset_start_region != NULL, "sanity"); 2569 assert(_worker_cset_start_region_time_stamp != NULL, "sanity"); 2570 2571 for (uint i = 0; i < ParallelGCThreads; i++) { 2572 _worker_cset_start_region[i] = NULL; 2573 _worker_cset_start_region_time_stamp[i] = 0; 2574 } 2575 } 2576 2577 // Given the id of a worker, obtain or calculate a suitable 2578 // starting region for iterating over the current collection set. 2579 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) { 2580 assert(get_gc_time_stamp() > 0, "should have been updated by now"); 2581 2582 HeapRegion* result = NULL; 2583 unsigned gc_time_stamp = get_gc_time_stamp(); 2584 2585 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) { 2586 // Cached starting region for current worker was set 2587 // during the current pause - so it's valid. 2588 // Note: the cached starting heap region may be NULL 2589 // (when the collection set is empty). 2590 result = _worker_cset_start_region[worker_i]; 2591 assert(result == NULL || result->in_collection_set(), "sanity"); 2592 return result; 2593 } 2594 2595 // The cached entry was not valid so let's calculate 2596 // a suitable starting heap region for this worker. 2597 2598 // We want the parallel threads to start their collection 2599 // set iteration at different collection set regions to 2600 // avoid contention. 2601 // If we have: 2602 // n collection set regions 2603 // p threads 2604 // Then thread t will start at region floor ((t * n) / p) 2605 2606 result = g1_policy()->collection_set(); 2607 uint cs_size = g1_policy()->cset_region_length(); 2608 uint active_workers = workers()->active_workers(); 2609 2610 uint end_ind = (cs_size * worker_i) / active_workers; 2611 uint start_ind = 0; 2612 2613 if (worker_i > 0 && 2614 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) { 2615 // Previous workers starting region is valid 2616 // so let's iterate from there 2617 start_ind = (cs_size * (worker_i - 1)) / active_workers; 2618 result = _worker_cset_start_region[worker_i - 1]; 2619 } 2620 2621 for (uint i = start_ind; i < end_ind; i++) { 2622 result = result->next_in_collection_set(); 2623 } 2624 2625 // Note: the calculated starting heap region may be NULL 2626 // (when the collection set is empty). 2627 assert(result == NULL || result->in_collection_set(), "sanity"); 2628 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp, 2629 "should be updated only once per pause"); 2630 _worker_cset_start_region[worker_i] = result; 2631 OrderAccess::storestore(); 2632 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp; 2633 return result; 2634 } 2635 2636 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) { 2637 HeapRegion* r = g1_policy()->collection_set(); 2638 while (r != NULL) { 2639 HeapRegion* next = r->next_in_collection_set(); 2640 if (cl->doHeapRegion(r)) { 2641 cl->incomplete(); 2642 return; 2643 } 2644 r = next; 2645 } 2646 } 2647 2648 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r, 2649 HeapRegionClosure *cl) { 2650 if (r == NULL) { 2651 // The CSet is empty so there's nothing to do. 2652 return; 2653 } 2654 2655 assert(r->in_collection_set(), 2656 "Start region must be a member of the collection set."); 2657 HeapRegion* cur = r; 2658 while (cur != NULL) { 2659 HeapRegion* next = cur->next_in_collection_set(); 2660 if (cl->doHeapRegion(cur) && false) { 2661 cl->incomplete(); 2662 return; 2663 } 2664 cur = next; 2665 } 2666 cur = g1_policy()->collection_set(); 2667 while (cur != r) { 2668 HeapRegion* next = cur->next_in_collection_set(); 2669 if (cl->doHeapRegion(cur) && false) { 2670 cl->incomplete(); 2671 return; 2672 } 2673 cur = next; 2674 } 2675 } 2676 2677 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const { 2678 HeapRegion* result = _hrm.next_region_in_heap(from); 2679 while (result != NULL && result->is_pinned()) { 2680 result = _hrm.next_region_in_heap(result); 2681 } 2682 return result; 2683 } 2684 2685 HeapWord* G1CollectedHeap::block_start(const void* addr) const { 2686 HeapRegion* hr = heap_region_containing(addr); 2687 return hr->block_start(addr); 2688 } 2689 2690 size_t G1CollectedHeap::block_size(const HeapWord* addr) const { 2691 HeapRegion* hr = heap_region_containing(addr); 2692 return hr->block_size(addr); 2693 } 2694 2695 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { 2696 HeapRegion* hr = heap_region_containing(addr); 2697 return hr->block_is_obj(addr); 2698 } 2699 2700 bool G1CollectedHeap::supports_tlab_allocation() const { 2701 return true; 2702 } 2703 2704 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { 2705 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes; 2706 } 2707 2708 size_t G1CollectedHeap::tlab_used(Thread* ignored) const { 2709 return young_list()->eden_used_bytes(); 2710 } 2711 2712 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size 2713 // must be equal to the humongous object limit. 2714 size_t G1CollectedHeap::max_tlab_size() const { 2715 return align_size_down(_humongous_object_threshold_in_words, MinObjAlignment); 2716 } 2717 2718 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { 2719 AllocationContext_t context = AllocationContext::current(); 2720 return _allocator->unsafe_max_tlab_alloc(context); 2721 } 2722 2723 size_t G1CollectedHeap::max_capacity() const { 2724 return _hrm.reserved().byte_size(); 2725 } 2726 2727 jlong G1CollectedHeap::millis_since_last_gc() { 2728 // assert(false, "NYI"); 2729 return 0; 2730 } 2731 2732 void G1CollectedHeap::prepare_for_verify() { 2733 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) { 2734 ensure_parsability(false); 2735 } 2736 g1_rem_set()->prepare_for_verify(); 2737 } 2738 2739 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr, 2740 VerifyOption vo) { 2741 switch (vo) { 2742 case VerifyOption_G1UsePrevMarking: 2743 return hr->obj_allocated_since_prev_marking(obj); 2744 case VerifyOption_G1UseNextMarking: 2745 return hr->obj_allocated_since_next_marking(obj); 2746 case VerifyOption_G1UseMarkWord: 2747 return false; 2748 default: 2749 ShouldNotReachHere(); 2750 } 2751 return false; // keep some compilers happy 2752 } 2753 2754 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) { 2755 switch (vo) { 2756 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start(); 2757 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start(); 2758 case VerifyOption_G1UseMarkWord: return NULL; 2759 default: ShouldNotReachHere(); 2760 } 2761 return NULL; // keep some compilers happy 2762 } 2763 2764 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) { 2765 switch (vo) { 2766 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj); 2767 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj); 2768 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked(); 2769 default: ShouldNotReachHere(); 2770 } 2771 return false; // keep some compilers happy 2772 } 2773 2774 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) { 2775 switch (vo) { 2776 case VerifyOption_G1UsePrevMarking: return "PTAMS"; 2777 case VerifyOption_G1UseNextMarking: return "NTAMS"; 2778 case VerifyOption_G1UseMarkWord: return "NONE"; 2779 default: ShouldNotReachHere(); 2780 } 2781 return NULL; // keep some compilers happy 2782 } 2783 2784 class VerifyRootsClosure: public OopClosure { 2785 private: 2786 G1CollectedHeap* _g1h; 2787 VerifyOption _vo; 2788 bool _failures; 2789 public: 2790 // _vo == UsePrevMarking -> use "prev" marking information, 2791 // _vo == UseNextMarking -> use "next" marking information, 2792 // _vo == UseMarkWord -> use mark word from object header. 2793 VerifyRootsClosure(VerifyOption vo) : 2794 _g1h(G1CollectedHeap::heap()), 2795 _vo(vo), 2796 _failures(false) { } 2797 2798 bool failures() { return _failures; } 2799 2800 template <class T> void do_oop_nv(T* p) { 2801 T heap_oop = oopDesc::load_heap_oop(p); 2802 if (!oopDesc::is_null(heap_oop)) { 2803 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 2804 if (_g1h->is_obj_dead_cond(obj, _vo)) { 2805 gclog_or_tty->print_cr("Root location " PTR_FORMAT " " 2806 "points to dead obj " PTR_FORMAT, p2i(p), p2i(obj)); 2807 if (_vo == VerifyOption_G1UseMarkWord) { 2808 gclog_or_tty->print_cr(" Mark word: " INTPTR_FORMAT, (intptr_t)obj->mark()); 2809 } 2810 obj->print_on(gclog_or_tty); 2811 _failures = true; 2812 } 2813 } 2814 } 2815 2816 void do_oop(oop* p) { do_oop_nv(p); } 2817 void do_oop(narrowOop* p) { do_oop_nv(p); } 2818 }; 2819 2820 class G1VerifyCodeRootOopClosure: public OopClosure { 2821 G1CollectedHeap* _g1h; 2822 OopClosure* _root_cl; 2823 nmethod* _nm; 2824 VerifyOption _vo; 2825 bool _failures; 2826 2827 template <class T> void do_oop_work(T* p) { 2828 // First verify that this root is live 2829 _root_cl->do_oop(p); 2830 2831 if (!G1VerifyHeapRegionCodeRoots) { 2832 // We're not verifying the code roots attached to heap region. 2833 return; 2834 } 2835 2836 // Don't check the code roots during marking verification in a full GC 2837 if (_vo == VerifyOption_G1UseMarkWord) { 2838 return; 2839 } 2840 2841 // Now verify that the current nmethod (which contains p) is 2842 // in the code root list of the heap region containing the 2843 // object referenced by p. 2844 2845 T heap_oop = oopDesc::load_heap_oop(p); 2846 if (!oopDesc::is_null(heap_oop)) { 2847 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 2848 2849 // Now fetch the region containing the object 2850 HeapRegion* hr = _g1h->heap_region_containing(obj); 2851 HeapRegionRemSet* hrrs = hr->rem_set(); 2852 // Verify that the strong code root list for this region 2853 // contains the nmethod 2854 if (!hrrs->strong_code_roots_list_contains(_nm)) { 2855 gclog_or_tty->print_cr("Code root location " PTR_FORMAT " " 2856 "from nmethod " PTR_FORMAT " not in strong " 2857 "code roots for region [" PTR_FORMAT "," PTR_FORMAT ")", 2858 p2i(p), p2i(_nm), p2i(hr->bottom()), p2i(hr->end())); 2859 _failures = true; 2860 } 2861 } 2862 } 2863 2864 public: 2865 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo): 2866 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {} 2867 2868 void do_oop(oop* p) { do_oop_work(p); } 2869 void do_oop(narrowOop* p) { do_oop_work(p); } 2870 2871 void set_nmethod(nmethod* nm) { _nm = nm; } 2872 bool failures() { return _failures; } 2873 }; 2874 2875 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure { 2876 G1VerifyCodeRootOopClosure* _oop_cl; 2877 2878 public: 2879 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl): 2880 _oop_cl(oop_cl) {} 2881 2882 void do_code_blob(CodeBlob* cb) { 2883 nmethod* nm = cb->as_nmethod_or_null(); 2884 if (nm != NULL) { 2885 _oop_cl->set_nmethod(nm); 2886 nm->oops_do(_oop_cl); 2887 } 2888 } 2889 }; 2890 2891 class YoungRefCounterClosure : public OopClosure { 2892 G1CollectedHeap* _g1h; 2893 int _count; 2894 public: 2895 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {} 2896 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } } 2897 void do_oop(narrowOop* p) { ShouldNotReachHere(); } 2898 2899 int count() { return _count; } 2900 void reset_count() { _count = 0; }; 2901 }; 2902 2903 class VerifyKlassClosure: public KlassClosure { 2904 YoungRefCounterClosure _young_ref_counter_closure; 2905 OopClosure *_oop_closure; 2906 public: 2907 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {} 2908 void do_klass(Klass* k) { 2909 k->oops_do(_oop_closure); 2910 2911 _young_ref_counter_closure.reset_count(); 2912 k->oops_do(&_young_ref_counter_closure); 2913 if (_young_ref_counter_closure.count() > 0) { 2914 guarantee(k->has_modified_oops(), "Klass " PTR_FORMAT ", has young refs but is not dirty.", p2i(k)); 2915 } 2916 } 2917 }; 2918 2919 class VerifyLivenessOopClosure: public OopClosure { 2920 G1CollectedHeap* _g1h; 2921 VerifyOption _vo; 2922 public: 2923 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo): 2924 _g1h(g1h), _vo(vo) 2925 { } 2926 void do_oop(narrowOop *p) { do_oop_work(p); } 2927 void do_oop( oop *p) { do_oop_work(p); } 2928 2929 template <class T> void do_oop_work(T *p) { 2930 oop obj = oopDesc::load_decode_heap_oop(p); 2931 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo), 2932 "Dead object referenced by a not dead object"); 2933 } 2934 }; 2935 2936 class VerifyObjsInRegionClosure: public ObjectClosure { 2937 private: 2938 G1CollectedHeap* _g1h; 2939 size_t _live_bytes; 2940 HeapRegion *_hr; 2941 VerifyOption _vo; 2942 public: 2943 // _vo == UsePrevMarking -> use "prev" marking information, 2944 // _vo == UseNextMarking -> use "next" marking information, 2945 // _vo == UseMarkWord -> use mark word from object header. 2946 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo) 2947 : _live_bytes(0), _hr(hr), _vo(vo) { 2948 _g1h = G1CollectedHeap::heap(); 2949 } 2950 void do_object(oop o) { 2951 VerifyLivenessOopClosure isLive(_g1h, _vo); 2952 assert(o != NULL, "Huh?"); 2953 if (!_g1h->is_obj_dead_cond(o, _vo)) { 2954 // If the object is alive according to the mark word, 2955 // then verify that the marking information agrees. 2956 // Note we can't verify the contra-positive of the 2957 // above: if the object is dead (according to the mark 2958 // word), it may not be marked, or may have been marked 2959 // but has since became dead, or may have been allocated 2960 // since the last marking. 2961 if (_vo == VerifyOption_G1UseMarkWord) { 2962 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch"); 2963 } 2964 2965 o->oop_iterate_no_header(&isLive); 2966 if (!_hr->obj_allocated_since_prev_marking(o)) { 2967 size_t obj_size = o->size(); // Make sure we don't overflow 2968 _live_bytes += (obj_size * HeapWordSize); 2969 } 2970 } 2971 } 2972 size_t live_bytes() { return _live_bytes; } 2973 }; 2974 2975 class VerifyArchiveOopClosure: public OopClosure { 2976 public: 2977 VerifyArchiveOopClosure(HeapRegion *hr) { } 2978 void do_oop(narrowOop *p) { do_oop_work(p); } 2979 void do_oop( oop *p) { do_oop_work(p); } 2980 2981 template <class T> void do_oop_work(T *p) { 2982 oop obj = oopDesc::load_decode_heap_oop(p); 2983 guarantee(obj == NULL || G1MarkSweep::in_archive_range(obj), 2984 "Archive object at " PTR_FORMAT " references a non-archive object at " PTR_FORMAT, 2985 p2i(p), p2i(obj)); 2986 } 2987 }; 2988 2989 class VerifyArchiveRegionClosure: public ObjectClosure { 2990 public: 2991 VerifyArchiveRegionClosure(HeapRegion *hr) { } 2992 // Verify that all object pointers are to archive regions. 2993 void do_object(oop o) { 2994 VerifyArchiveOopClosure checkOop(NULL); 2995 assert(o != NULL, "Should not be here for NULL oops"); 2996 o->oop_iterate_no_header(&checkOop); 2997 } 2998 }; 2999 3000 class VerifyRegionClosure: public HeapRegionClosure { 3001 private: 3002 bool _par; 3003 VerifyOption _vo; 3004 bool _failures; 3005 public: 3006 // _vo == UsePrevMarking -> use "prev" marking information, 3007 // _vo == UseNextMarking -> use "next" marking information, 3008 // _vo == UseMarkWord -> use mark word from object header. 3009 VerifyRegionClosure(bool par, VerifyOption vo) 3010 : _par(par), 3011 _vo(vo), 3012 _failures(false) {} 3013 3014 bool failures() { 3015 return _failures; 3016 } 3017 3018 bool doHeapRegion(HeapRegion* r) { 3019 // For archive regions, verify there are no heap pointers to 3020 // non-pinned regions. For all others, verify liveness info. 3021 if (r->is_archive()) { 3022 VerifyArchiveRegionClosure verify_oop_pointers(r); 3023 r->object_iterate(&verify_oop_pointers); 3024 return true; 3025 } 3026 if (!r->is_continues_humongous()) { 3027 bool failures = false; 3028 r->verify(_vo, &failures); 3029 if (failures) { 3030 _failures = true; 3031 } else if (!r->is_starts_humongous()) { 3032 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo); 3033 r->object_iterate(¬_dead_yet_cl); 3034 if (_vo != VerifyOption_G1UseNextMarking) { 3035 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) { 3036 gclog_or_tty->print_cr("[" PTR_FORMAT "," PTR_FORMAT "] " 3037 "max_live_bytes " SIZE_FORMAT " " 3038 "< calculated " SIZE_FORMAT, 3039 p2i(r->bottom()), p2i(r->end()), 3040 r->max_live_bytes(), 3041 not_dead_yet_cl.live_bytes()); 3042 _failures = true; 3043 } 3044 } else { 3045 // When vo == UseNextMarking we cannot currently do a sanity 3046 // check on the live bytes as the calculation has not been 3047 // finalized yet. 3048 } 3049 } 3050 } 3051 return false; // stop the region iteration if we hit a failure 3052 } 3053 }; 3054 3055 // This is the task used for parallel verification of the heap regions 3056 3057 class G1ParVerifyTask: public AbstractGangTask { 3058 private: 3059 G1CollectedHeap* _g1h; 3060 VerifyOption _vo; 3061 bool _failures; 3062 HeapRegionClaimer _hrclaimer; 3063 3064 public: 3065 // _vo == UsePrevMarking -> use "prev" marking information, 3066 // _vo == UseNextMarking -> use "next" marking information, 3067 // _vo == UseMarkWord -> use mark word from object header. 3068 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) : 3069 AbstractGangTask("Parallel verify task"), 3070 _g1h(g1h), 3071 _vo(vo), 3072 _failures(false), 3073 _hrclaimer(g1h->workers()->active_workers()) {} 3074 3075 bool failures() { 3076 return _failures; 3077 } 3078 3079 void work(uint worker_id) { 3080 HandleMark hm; 3081 VerifyRegionClosure blk(true, _vo); 3082 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer); 3083 if (blk.failures()) { 3084 _failures = true; 3085 } 3086 } 3087 }; 3088 3089 void G1CollectedHeap::verify(bool silent, VerifyOption vo) { 3090 if (SafepointSynchronize::is_at_safepoint()) { 3091 assert(Thread::current()->is_VM_thread(), 3092 "Expected to be executed serially by the VM thread at this point"); 3093 3094 if (!silent) { gclog_or_tty->print("Roots "); } 3095 VerifyRootsClosure rootsCl(vo); 3096 VerifyKlassClosure klassCl(this, &rootsCl); 3097 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false); 3098 3099 // We apply the relevant closures to all the oops in the 3100 // system dictionary, class loader data graph, the string table 3101 // and the nmethods in the code cache. 3102 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo); 3103 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl); 3104 3105 { 3106 G1RootProcessor root_processor(this, 1); 3107 root_processor.process_all_roots(&rootsCl, 3108 &cldCl, 3109 &blobsCl); 3110 } 3111 3112 bool failures = rootsCl.failures() || codeRootsCl.failures(); 3113 3114 if (vo != VerifyOption_G1UseMarkWord) { 3115 // If we're verifying during a full GC then the region sets 3116 // will have been torn down at the start of the GC. Therefore 3117 // verifying the region sets will fail. So we only verify 3118 // the region sets when not in a full GC. 3119 if (!silent) { gclog_or_tty->print("HeapRegionSets "); } 3120 verify_region_sets(); 3121 } 3122 3123 if (!silent) { gclog_or_tty->print("HeapRegions "); } 3124 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) { 3125 3126 G1ParVerifyTask task(this, vo); 3127 workers()->run_task(&task); 3128 if (task.failures()) { 3129 failures = true; 3130 } 3131 3132 } else { 3133 VerifyRegionClosure blk(false, vo); 3134 heap_region_iterate(&blk); 3135 if (blk.failures()) { 3136 failures = true; 3137 } 3138 } 3139 3140 if (G1StringDedup::is_enabled()) { 3141 if (!silent) gclog_or_tty->print("StrDedup "); 3142 G1StringDedup::verify(); 3143 } 3144 3145 if (failures) { 3146 gclog_or_tty->print_cr("Heap:"); 3147 // It helps to have the per-region information in the output to 3148 // help us track down what went wrong. This is why we call 3149 // print_extended_on() instead of print_on(). 3150 print_extended_on(gclog_or_tty); 3151 gclog_or_tty->cr(); 3152 gclog_or_tty->flush(); 3153 } 3154 guarantee(!failures, "there should not have been any failures"); 3155 } else { 3156 if (!silent) { 3157 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet"); 3158 if (G1StringDedup::is_enabled()) { 3159 gclog_or_tty->print(", StrDedup"); 3160 } 3161 gclog_or_tty->print(") "); 3162 } 3163 } 3164 } 3165 3166 void G1CollectedHeap::verify(bool silent) { 3167 verify(silent, VerifyOption_G1UsePrevMarking); 3168 } 3169 3170 double G1CollectedHeap::verify(bool guard, const char* msg) { 3171 double verify_time_ms = 0.0; 3172 3173 if (guard && total_collections() >= VerifyGCStartAt) { 3174 double verify_start = os::elapsedTime(); 3175 HandleMark hm; // Discard invalid handles created during verification 3176 prepare_for_verify(); 3177 Universe::verify(VerifyOption_G1UsePrevMarking, msg); 3178 verify_time_ms = (os::elapsedTime() - verify_start) * 1000; 3179 } 3180 3181 return verify_time_ms; 3182 } 3183 3184 void G1CollectedHeap::verify_before_gc() { 3185 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:"); 3186 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms); 3187 } 3188 3189 void G1CollectedHeap::verify_after_gc() { 3190 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:"); 3191 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms); 3192 } 3193 3194 class PrintRegionClosure: public HeapRegionClosure { 3195 outputStream* _st; 3196 public: 3197 PrintRegionClosure(outputStream* st) : _st(st) {} 3198 bool doHeapRegion(HeapRegion* r) { 3199 r->print_on(_st); 3200 return false; 3201 } 3202 }; 3203 3204 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 3205 const HeapRegion* hr, 3206 const VerifyOption vo) const { 3207 switch (vo) { 3208 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); 3209 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); 3210 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked() && !hr->is_archive(); 3211 default: ShouldNotReachHere(); 3212 } 3213 return false; // keep some compilers happy 3214 } 3215 3216 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 3217 const VerifyOption vo) const { 3218 switch (vo) { 3219 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); 3220 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); 3221 case VerifyOption_G1UseMarkWord: { 3222 HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj); 3223 return !obj->is_gc_marked() && !hr->is_archive(); 3224 } 3225 default: ShouldNotReachHere(); 3226 } 3227 return false; // keep some compilers happy 3228 } 3229 3230 void G1CollectedHeap::print_on(outputStream* st) const { 3231 st->print(" %-20s", "garbage-first heap"); 3232 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 3233 capacity()/K, used_unlocked()/K); 3234 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")", 3235 p2i(_hrm.reserved().start()), 3236 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords), 3237 p2i(_hrm.reserved().end())); 3238 st->cr(); 3239 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); 3240 uint young_regions = _young_list->length(); 3241 st->print("%u young (" SIZE_FORMAT "K), ", young_regions, 3242 (size_t) young_regions * HeapRegion::GrainBytes / K); 3243 uint survivor_regions = g1_policy()->recorded_survivor_regions(); 3244 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, 3245 (size_t) survivor_regions * HeapRegion::GrainBytes / K); 3246 st->cr(); 3247 MetaspaceAux::print_on(st); 3248 } 3249 3250 void G1CollectedHeap::print_extended_on(outputStream* st) const { 3251 print_on(st); 3252 3253 // Print the per-region information. 3254 st->cr(); 3255 st->print_cr("Heap Regions: (E=young(eden), S=young(survivor), O=old, " 3256 "HS=humongous(starts), HC=humongous(continues), " 3257 "CS=collection set, F=free, A=archive, TS=gc time stamp, " 3258 "PTAMS=previous top-at-mark-start, " 3259 "NTAMS=next top-at-mark-start)"); 3260 PrintRegionClosure blk(st); 3261 heap_region_iterate(&blk); 3262 } 3263 3264 void G1CollectedHeap::print_on_error(outputStream* st) const { 3265 this->CollectedHeap::print_on_error(st); 3266 3267 if (_cm != NULL) { 3268 st->cr(); 3269 _cm->print_on_error(st); 3270 } 3271 } 3272 3273 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const { 3274 workers()->print_worker_threads_on(st); 3275 _cmThread->print_on(st); 3276 st->cr(); 3277 _cm->print_worker_threads_on(st); 3278 _cg1r->print_worker_threads_on(st); 3279 if (G1StringDedup::is_enabled()) { 3280 G1StringDedup::print_worker_threads_on(st); 3281 } 3282 } 3283 3284 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { 3285 workers()->threads_do(tc); 3286 tc->do_thread(_cmThread); 3287 _cg1r->threads_do(tc); 3288 if (G1StringDedup::is_enabled()) { 3289 G1StringDedup::threads_do(tc); 3290 } 3291 } 3292 3293 void G1CollectedHeap::print_tracing_info() const { 3294 // We'll overload this to mean "trace GC pause statistics." 3295 if (TraceYoungGenTime || TraceOldGenTime) { 3296 // The "G1CollectorPolicy" is keeping track of these stats, so delegate 3297 // to that. 3298 g1_policy()->print_tracing_info(); 3299 } 3300 if (G1SummarizeRSetStats) { 3301 g1_rem_set()->print_summary_info(); 3302 } 3303 if (G1SummarizeConcMark) { 3304 concurrent_mark()->print_summary_info(); 3305 } 3306 g1_policy()->print_yg_surv_rate_info(); 3307 } 3308 3309 #ifndef PRODUCT 3310 // Helpful for debugging RSet issues. 3311 3312 class PrintRSetsClosure : public HeapRegionClosure { 3313 private: 3314 const char* _msg; 3315 size_t _occupied_sum; 3316 3317 public: 3318 bool doHeapRegion(HeapRegion* r) { 3319 HeapRegionRemSet* hrrs = r->rem_set(); 3320 size_t occupied = hrrs->occupied(); 3321 _occupied_sum += occupied; 3322 3323 gclog_or_tty->print_cr("Printing RSet for region " HR_FORMAT, 3324 HR_FORMAT_PARAMS(r)); 3325 if (occupied == 0) { 3326 gclog_or_tty->print_cr(" RSet is empty"); 3327 } else { 3328 hrrs->print(); 3329 } 3330 gclog_or_tty->print_cr("----------"); 3331 return false; 3332 } 3333 3334 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { 3335 gclog_or_tty->cr(); 3336 gclog_or_tty->print_cr("========================================"); 3337 gclog_or_tty->print_cr("%s", msg); 3338 gclog_or_tty->cr(); 3339 } 3340 3341 ~PrintRSetsClosure() { 3342 gclog_or_tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum); 3343 gclog_or_tty->print_cr("========================================"); 3344 gclog_or_tty->cr(); 3345 } 3346 }; 3347 3348 void G1CollectedHeap::print_cset_rsets() { 3349 PrintRSetsClosure cl("Printing CSet RSets"); 3350 collection_set_iterate(&cl); 3351 } 3352 3353 void G1CollectedHeap::print_all_rsets() { 3354 PrintRSetsClosure cl("Printing All RSets");; 3355 heap_region_iterate(&cl); 3356 } 3357 #endif // PRODUCT 3358 3359 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() { 3360 YoungList* young_list = heap()->young_list(); 3361 3362 size_t eden_used_bytes = young_list->eden_used_bytes(); 3363 size_t survivor_used_bytes = young_list->survivor_used_bytes(); 3364 3365 size_t eden_capacity_bytes = 3366 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes; 3367 3368 VirtualSpaceSummary heap_summary = create_heap_space_summary(); 3369 return G1HeapSummary(heap_summary, used(), eden_used_bytes, eden_capacity_bytes, survivor_used_bytes); 3370 } 3371 3372 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) { 3373 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(), 3374 stats->unused(), stats->used(), stats->region_end_waste(), 3375 stats->regions_filled(), stats->direct_allocated(), 3376 stats->failure_used(), stats->failure_waste()); 3377 } 3378 3379 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) { 3380 const G1HeapSummary& heap_summary = create_g1_heap_summary(); 3381 gc_tracer->report_gc_heap_summary(when, heap_summary); 3382 3383 const MetaspaceSummary& metaspace_summary = create_metaspace_summary(); 3384 gc_tracer->report_metaspace_summary(when, metaspace_summary); 3385 } 3386 3387 3388 G1CollectedHeap* G1CollectedHeap::heap() { 3389 CollectedHeap* heap = Universe::heap(); 3390 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()"); 3391 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap"); 3392 return (G1CollectedHeap*)heap; 3393 } 3394 3395 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) { 3396 // always_do_update_barrier = false; 3397 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 3398 // Fill TLAB's and such 3399 accumulate_statistics_all_tlabs(); 3400 ensure_parsability(true); 3401 3402 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) && 3403 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) { 3404 g1_rem_set()->print_periodic_summary_info("Before GC RS summary"); 3405 } 3406 } 3407 3408 void G1CollectedHeap::gc_epilogue(bool full) { 3409 3410 if (G1SummarizeRSetStats && 3411 (G1SummarizeRSetStatsPeriod > 0) && 3412 // we are at the end of the GC. Total collections has already been increased. 3413 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) { 3414 g1_rem_set()->print_periodic_summary_info("After GC RS summary"); 3415 } 3416 3417 // FIXME: what is this about? 3418 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" 3419 // is set. 3420 #if defined(COMPILER2) || INCLUDE_JVMCI 3421 assert(DerivedPointerTable::is_empty(), "derived pointer present"); 3422 #endif 3423 // always_do_update_barrier = true; 3424 3425 resize_all_tlabs(); 3426 allocation_context_stats().update(full); 3427 3428 // We have just completed a GC. Update the soft reference 3429 // policy with the new heap occupancy 3430 Universe::update_heap_info_at_gc(); 3431 } 3432 3433 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, 3434 uint gc_count_before, 3435 bool* succeeded, 3436 GCCause::Cause gc_cause) { 3437 assert_heap_not_locked_and_not_at_safepoint(); 3438 g1_policy()->record_stop_world_start(); 3439 VM_G1IncCollectionPause op(gc_count_before, 3440 word_size, 3441 false, /* should_initiate_conc_mark */ 3442 g1_policy()->max_pause_time_ms(), 3443 gc_cause); 3444 3445 op.set_allocation_context(AllocationContext::current()); 3446 VMThread::execute(&op); 3447 3448 HeapWord* result = op.result(); 3449 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded(); 3450 assert(result == NULL || ret_succeeded, 3451 "the result should be NULL if the VM did not succeed"); 3452 *succeeded = ret_succeeded; 3453 3454 assert_heap_not_locked(); 3455 return result; 3456 } 3457 3458 void 3459 G1CollectedHeap::doConcurrentMark() { 3460 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); 3461 if (!_cmThread->in_progress()) { 3462 _cmThread->set_started(); 3463 CGC_lock->notify(); 3464 } 3465 } 3466 3467 size_t G1CollectedHeap::pending_card_num() { 3468 size_t extra_cards = 0; 3469 JavaThread *curr = Threads::first(); 3470 while (curr != NULL) { 3471 DirtyCardQueue& dcq = curr->dirty_card_queue(); 3472 extra_cards += dcq.size(); 3473 curr = curr->next(); 3474 } 3475 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 3476 size_t buffer_size = dcqs.buffer_size(); 3477 size_t buffer_num = dcqs.completed_buffers_num(); 3478 3479 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes 3480 // in bytes - not the number of 'entries'. We need to convert 3481 // into a number of cards. 3482 return (buffer_size * buffer_num + extra_cards) / oopSize; 3483 } 3484 3485 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure { 3486 private: 3487 size_t _total_humongous; 3488 size_t _candidate_humongous; 3489 3490 DirtyCardQueue _dcq; 3491 3492 // We don't nominate objects with many remembered set entries, on 3493 // the assumption that such objects are likely still live. 3494 bool is_remset_small(HeapRegion* region) const { 3495 HeapRegionRemSet* const rset = region->rem_set(); 3496 return G1EagerReclaimHumongousObjectsWithStaleRefs 3497 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) 3498 : rset->is_empty(); 3499 } 3500 3501 bool is_typeArray_region(HeapRegion* region) const { 3502 return oop(region->bottom())->is_typeArray(); 3503 } 3504 3505 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const { 3506 assert(region->is_starts_humongous(), "Must start a humongous object"); 3507 3508 // Candidate selection must satisfy the following constraints 3509 // while concurrent marking is in progress: 3510 // 3511 // * In order to maintain SATB invariants, an object must not be 3512 // reclaimed if it was allocated before the start of marking and 3513 // has not had its references scanned. Such an object must have 3514 // its references (including type metadata) scanned to ensure no 3515 // live objects are missed by the marking process. Objects 3516 // allocated after the start of concurrent marking don't need to 3517 // be scanned. 3518 // 3519 // * An object must not be reclaimed if it is on the concurrent 3520 // mark stack. Objects allocated after the start of concurrent 3521 // marking are never pushed on the mark stack. 3522 // 3523 // Nominating only objects allocated after the start of concurrent 3524 // marking is sufficient to meet both constraints. This may miss 3525 // some objects that satisfy the constraints, but the marking data 3526 // structures don't support efficiently performing the needed 3527 // additional tests or scrubbing of the mark stack. 3528 // 3529 // However, we presently only nominate is_typeArray() objects. 3530 // A humongous object containing references induces remembered 3531 // set entries on other regions. In order to reclaim such an 3532 // object, those remembered sets would need to be cleaned up. 3533 // 3534 // We also treat is_typeArray() objects specially, allowing them 3535 // to be reclaimed even if allocated before the start of 3536 // concurrent mark. For this we rely on mark stack insertion to 3537 // exclude is_typeArray() objects, preventing reclaiming an object 3538 // that is in the mark stack. We also rely on the metadata for 3539 // such objects to be built-in and so ensured to be kept live. 3540 // Frequent allocation and drop of large binary blobs is an 3541 // important use case for eager reclaim, and this special handling 3542 // may reduce needed headroom. 3543 3544 return is_typeArray_region(region) && is_remset_small(region); 3545 } 3546 3547 public: 3548 RegisterHumongousWithInCSetFastTestClosure() 3549 : _total_humongous(0), 3550 _candidate_humongous(0), 3551 _dcq(&JavaThread::dirty_card_queue_set()) { 3552 } 3553 3554 virtual bool doHeapRegion(HeapRegion* r) { 3555 if (!r->is_starts_humongous()) { 3556 return false; 3557 } 3558 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 3559 3560 bool is_candidate = humongous_region_is_candidate(g1h, r); 3561 uint rindex = r->hrm_index(); 3562 g1h->set_humongous_reclaim_candidate(rindex, is_candidate); 3563 if (is_candidate) { 3564 _candidate_humongous++; 3565 g1h->register_humongous_region_with_cset(rindex); 3566 // Is_candidate already filters out humongous object with large remembered sets. 3567 // If we have a humongous object with a few remembered sets, we simply flush these 3568 // remembered set entries into the DCQS. That will result in automatic 3569 // re-evaluation of their remembered set entries during the following evacuation 3570 // phase. 3571 if (!r->rem_set()->is_empty()) { 3572 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries), 3573 "Found a not-small remembered set here. This is inconsistent with previous assumptions."); 3574 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set(); 3575 HeapRegionRemSetIterator hrrs(r->rem_set()); 3576 size_t card_index; 3577 while (hrrs.has_next(card_index)) { 3578 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index); 3579 // The remembered set might contain references to already freed 3580 // regions. Filter out such entries to avoid failing card table 3581 // verification. 3582 if (!g1h->heap_region_containing(bs->addr_for(card_ptr))->is_free()) { 3583 if (*card_ptr != CardTableModRefBS::dirty_card_val()) { 3584 *card_ptr = CardTableModRefBS::dirty_card_val(); 3585 _dcq.enqueue(card_ptr); 3586 } 3587 } 3588 } 3589 r->rem_set()->clear_locked(); 3590 } 3591 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty."); 3592 } 3593 _total_humongous++; 3594 3595 return false; 3596 } 3597 3598 size_t total_humongous() const { return _total_humongous; } 3599 size_t candidate_humongous() const { return _candidate_humongous; } 3600 3601 void flush_rem_set_entries() { _dcq.flush(); } 3602 }; 3603 3604 void G1CollectedHeap::register_humongous_regions_with_cset() { 3605 if (!G1EagerReclaimHumongousObjects) { 3606 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0); 3607 return; 3608 } 3609 double time = os::elapsed_counter(); 3610 3611 // Collect reclaim candidate information and register candidates with cset. 3612 RegisterHumongousWithInCSetFastTestClosure cl; 3613 heap_region_iterate(&cl); 3614 3615 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0; 3616 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time, 3617 cl.total_humongous(), 3618 cl.candidate_humongous()); 3619 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0; 3620 3621 // Finally flush all remembered set entries to re-check into the global DCQS. 3622 cl.flush_rem_set_entries(); 3623 } 3624 3625 #ifdef ASSERT 3626 class VerifyCSetClosure: public HeapRegionClosure { 3627 public: 3628 bool doHeapRegion(HeapRegion* hr) { 3629 // Here we check that the CSet region's RSet is ready for parallel 3630 // iteration. The fields that we'll verify are only manipulated 3631 // when the region is part of a CSet and is collected. Afterwards, 3632 // we reset these fields when we clear the region's RSet (when the 3633 // region is freed) so they are ready when the region is 3634 // re-allocated. The only exception to this is if there's an 3635 // evacuation failure and instead of freeing the region we leave 3636 // it in the heap. In that case, we reset these fields during 3637 // evacuation failure handling. 3638 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification"); 3639 3640 // Here's a good place to add any other checks we'd like to 3641 // perform on CSet regions. 3642 return false; 3643 } 3644 }; 3645 #endif // ASSERT 3646 3647 uint G1CollectedHeap::num_task_queues() const { 3648 return _task_queues->size(); 3649 } 3650 3651 #if TASKQUEUE_STATS 3652 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) { 3653 st->print_raw_cr("GC Task Stats"); 3654 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); 3655 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); 3656 } 3657 3658 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const { 3659 print_taskqueue_stats_hdr(st); 3660 3661 TaskQueueStats totals; 3662 const uint n = num_task_queues(); 3663 for (uint i = 0; i < n; ++i) { 3664 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr(); 3665 totals += task_queue(i)->stats; 3666 } 3667 st->print_raw("tot "); totals.print(st); st->cr(); 3668 3669 DEBUG_ONLY(totals.verify()); 3670 } 3671 3672 void G1CollectedHeap::reset_taskqueue_stats() { 3673 const uint n = num_task_queues(); 3674 for (uint i = 0; i < n; ++i) { 3675 task_queue(i)->stats.reset(); 3676 } 3677 } 3678 #endif // TASKQUEUE_STATS 3679 3680 void G1CollectedHeap::log_gc_header() { 3681 if (!G1Log::fine()) { 3682 return; 3683 } 3684 3685 gclog_or_tty->gclog_stamp(); 3686 3687 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause()) 3688 .append(collector_state()->gcs_are_young() ? "(young)" : "(mixed)") 3689 .append(collector_state()->during_initial_mark_pause() ? " (initial-mark)" : ""); 3690 3691 gclog_or_tty->print("[%s", (const char*)gc_cause_str); 3692 } 3693 3694 void G1CollectedHeap::log_gc_footer(double pause_time_sec) { 3695 if (!G1Log::fine()) { 3696 return; 3697 } 3698 3699 if (G1Log::finer()) { 3700 if (evacuation_failed()) { 3701 gclog_or_tty->print(" (to-space exhausted)"); 3702 } 3703 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec); 3704 g1_policy()->print_phases(pause_time_sec); 3705 g1_policy()->print_detailed_heap_transition(); 3706 } else { 3707 if (evacuation_failed()) { 3708 gclog_or_tty->print("--"); 3709 } 3710 g1_policy()->print_heap_transition(); 3711 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec); 3712 } 3713 gclog_or_tty->flush(); 3714 } 3715 3716 void G1CollectedHeap::wait_for_root_region_scanning() { 3717 double scan_wait_start = os::elapsedTime(); 3718 // We have to wait until the CM threads finish scanning the 3719 // root regions as it's the only way to ensure that all the 3720 // objects on them have been correctly scanned before we start 3721 // moving them during the GC. 3722 bool waited = _cm->root_regions()->wait_until_scan_finished(); 3723 double wait_time_ms = 0.0; 3724 if (waited) { 3725 double scan_wait_end = os::elapsedTime(); 3726 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0; 3727 } 3728 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms); 3729 } 3730 3731 bool 3732 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { 3733 assert_at_safepoint(true /* should_be_vm_thread */); 3734 guarantee(!is_gc_active(), "collection is not reentrant"); 3735 3736 if (GC_locker::check_active_before_gc()) { 3737 return false; 3738 } 3739 3740 _gc_timer_stw->register_gc_start(); 3741 3742 GCIdMark gc_id_mark; 3743 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start()); 3744 3745 SvcGCMarker sgcm(SvcGCMarker::MINOR); 3746 ResourceMark rm; 3747 3748 wait_for_root_region_scanning(); 3749 3750 G1Log::update_level(); 3751 print_heap_before_gc(); 3752 trace_heap_before_gc(_gc_tracer_stw); 3753 3754 verify_region_sets_optional(); 3755 verify_dirty_young_regions(); 3756 3757 // This call will decide whether this pause is an initial-mark 3758 // pause. If it is, during_initial_mark_pause() will return true 3759 // for the duration of this pause. 3760 g1_policy()->decide_on_conc_mark_initiation(); 3761 3762 // We do not allow initial-mark to be piggy-backed on a mixed GC. 3763 assert(!collector_state()->during_initial_mark_pause() || 3764 collector_state()->gcs_are_young(), "sanity"); 3765 3766 // We also do not allow mixed GCs during marking. 3767 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity"); 3768 3769 // Record whether this pause is an initial mark. When the current 3770 // thread has completed its logging output and it's safe to signal 3771 // the CM thread, the flag's value in the policy has been reset. 3772 bool should_start_conc_mark = collector_state()->during_initial_mark_pause(); 3773 3774 // Inner scope for scope based logging, timers, and stats collection 3775 { 3776 EvacuationInfo evacuation_info; 3777 3778 if (collector_state()->during_initial_mark_pause()) { 3779 // We are about to start a marking cycle, so we increment the 3780 // full collection counter. 3781 increment_old_marking_cycles_started(); 3782 register_concurrent_cycle_start(_gc_timer_stw->gc_start()); 3783 } 3784 3785 _gc_tracer_stw->report_yc_type(collector_state()->yc_type()); 3786 3787 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty); 3788 3789 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 3790 workers()->active_workers(), 3791 Threads::number_of_non_daemon_threads()); 3792 workers()->set_active_workers(active_workers); 3793 3794 double pause_start_sec = os::elapsedTime(); 3795 g1_policy()->note_gc_start(active_workers); 3796 log_gc_header(); 3797 3798 TraceCollectorStats tcs(g1mm()->incremental_collection_counters()); 3799 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause()); 3800 3801 // If the secondary_free_list is not empty, append it to the 3802 // free_list. No need to wait for the cleanup operation to finish; 3803 // the region allocation code will check the secondary_free_list 3804 // and wait if necessary. If the G1StressConcRegionFreeing flag is 3805 // set, skip this step so that the region allocation code has to 3806 // get entries from the secondary_free_list. 3807 if (!G1StressConcRegionFreeing) { 3808 append_secondary_free_list_if_not_empty_with_lock(); 3809 } 3810 3811 assert(check_young_list_well_formed(), "young list should be well formed"); 3812 3813 // Don't dynamically change the number of GC threads this early. A value of 3814 // 0 is used to indicate serial work. When parallel work is done, 3815 // it will be set. 3816 3817 { // Call to jvmpi::post_class_unload_events must occur outside of active GC 3818 IsGCActiveMark x; 3819 3820 gc_prologue(false); 3821 increment_total_collections(false /* full gc */); 3822 increment_gc_time_stamp(); 3823 3824 verify_before_gc(); 3825 3826 check_bitmaps("GC Start"); 3827 3828 #if defined(COMPILER2) || INCLUDE_JVMCI 3829 DerivedPointerTable::clear(); 3830 #endif 3831 3832 // Please see comment in g1CollectedHeap.hpp and 3833 // G1CollectedHeap::ref_processing_init() to see how 3834 // reference processing currently works in G1. 3835 3836 // Enable discovery in the STW reference processor 3837 ref_processor_stw()->enable_discovery(); 3838 3839 { 3840 // We want to temporarily turn off discovery by the 3841 // CM ref processor, if necessary, and turn it back on 3842 // on again later if we do. Using a scoped 3843 // NoRefDiscovery object will do this. 3844 NoRefDiscovery no_cm_discovery(ref_processor_cm()); 3845 3846 // Forget the current alloc region (we might even choose it to be part 3847 // of the collection set!). 3848 _allocator->release_mutator_alloc_region(); 3849 3850 // We should call this after we retire the mutator alloc 3851 // region(s) so that all the ALLOC / RETIRE events are generated 3852 // before the start GC event. 3853 _hr_printer.start_gc(false /* full */, (size_t) total_collections()); 3854 3855 // This timing is only used by the ergonomics to handle our pause target. 3856 // It is unclear why this should not include the full pause. We will 3857 // investigate this in CR 7178365. 3858 // 3859 // Preserving the old comment here if that helps the investigation: 3860 // 3861 // The elapsed time induced by the start time below deliberately elides 3862 // the possible verification above. 3863 double sample_start_time_sec = os::elapsedTime(); 3864 3865 g1_policy()->record_collection_pause_start(sample_start_time_sec); 3866 3867 if (collector_state()->during_initial_mark_pause()) { 3868 concurrent_mark()->checkpointRootsInitialPre(); 3869 } 3870 3871 double time_remaining_ms = g1_policy()->finalize_young_cset_part(target_pause_time_ms); 3872 g1_policy()->finalize_old_cset_part(time_remaining_ms); 3873 3874 evacuation_info.set_collectionset_regions(g1_policy()->cset_region_length()); 3875 3876 register_humongous_regions_with_cset(); 3877 3878 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table."); 3879 3880 _cm->note_start_of_gc(); 3881 // We call this after finalize_cset() to 3882 // ensure that the CSet has been finalized. 3883 _cm->verify_no_cset_oops(); 3884 3885 if (_hr_printer.is_active()) { 3886 HeapRegion* hr = g1_policy()->collection_set(); 3887 while (hr != NULL) { 3888 _hr_printer.cset(hr); 3889 hr = hr->next_in_collection_set(); 3890 } 3891 } 3892 3893 #ifdef ASSERT 3894 VerifyCSetClosure cl; 3895 collection_set_iterate(&cl); 3896 #endif // ASSERT 3897 3898 // Initialize the GC alloc regions. 3899 _allocator->init_gc_alloc_regions(evacuation_info); 3900 3901 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), g1_policy()->young_cset_region_length()); 3902 pre_evacuate_collection_set(); 3903 3904 // Actually do the work... 3905 evacuate_collection_set(evacuation_info, &per_thread_states); 3906 3907 post_evacuate_collection_set(evacuation_info, &per_thread_states); 3908 3909 const size_t* surviving_young_words = per_thread_states.surviving_young_words(); 3910 free_collection_set(g1_policy()->collection_set(), evacuation_info, surviving_young_words); 3911 3912 eagerly_reclaim_humongous_regions(); 3913 3914 g1_policy()->clear_collection_set(); 3915 3916 // Start a new incremental collection set for the next pause. 3917 g1_policy()->start_incremental_cset_building(); 3918 3919 clear_cset_fast_test(); 3920 3921 _young_list->reset_sampled_info(); 3922 3923 // Don't check the whole heap at this point as the 3924 // GC alloc regions from this pause have been tagged 3925 // as survivors and moved on to the survivor list. 3926 // Survivor regions will fail the !is_young() check. 3927 assert(check_young_list_empty(false /* check_heap */), 3928 "young list should be empty"); 3929 3930 g1_policy()->record_survivor_regions(_young_list->survivor_length(), 3931 _young_list->first_survivor_region(), 3932 _young_list->last_survivor_region()); 3933 3934 _young_list->reset_auxilary_lists(); 3935 3936 if (evacuation_failed()) { 3937 set_used(recalculate_used()); 3938 if (_archive_allocator != NULL) { 3939 _archive_allocator->clear_used(); 3940 } 3941 for (uint i = 0; i < ParallelGCThreads; i++) { 3942 if (_evacuation_failed_info_array[i].has_failed()) { 3943 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]); 3944 } 3945 } 3946 } else { 3947 // The "used" of the the collection set have already been subtracted 3948 // when they were freed. Add in the bytes evacuated. 3949 increase_used(g1_policy()->bytes_copied_during_gc()); 3950 } 3951 3952 if (collector_state()->during_initial_mark_pause()) { 3953 // We have to do this before we notify the CM threads that 3954 // they can start working to make sure that all the 3955 // appropriate initialization is done on the CM object. 3956 concurrent_mark()->checkpointRootsInitialPost(); 3957 collector_state()->set_mark_in_progress(true); 3958 // Note that we don't actually trigger the CM thread at 3959 // this point. We do that later when we're sure that 3960 // the current thread has completed its logging output. 3961 } 3962 3963 allocate_dummy_regions(); 3964 3965 _allocator->init_mutator_alloc_region(); 3966 3967 { 3968 size_t expand_bytes = g1_policy()->expansion_amount(); 3969 if (expand_bytes > 0) { 3970 size_t bytes_before = capacity(); 3971 // No need for an ergo verbose message here, 3972 // expansion_amount() does this when it returns a value > 0. 3973 double expand_ms; 3974 if (!expand(expand_bytes, &expand_ms)) { 3975 // We failed to expand the heap. Cannot do anything about it. 3976 } 3977 g1_policy()->phase_times()->record_expand_heap_time(expand_ms); 3978 } 3979 } 3980 3981 // We redo the verification but now wrt to the new CSet which 3982 // has just got initialized after the previous CSet was freed. 3983 _cm->verify_no_cset_oops(); 3984 _cm->note_end_of_gc(); 3985 3986 // This timing is only used by the ergonomics to handle our pause target. 3987 // It is unclear why this should not include the full pause. We will 3988 // investigate this in CR 7178365. 3989 double sample_end_time_sec = os::elapsedTime(); 3990 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; 3991 size_t total_cards_scanned = per_thread_states.total_cards_scanned(); 3992 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned); 3993 3994 evacuation_info.set_collectionset_used_before(g1_policy()->collection_set_bytes_used_before()); 3995 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc()); 3996 3997 MemoryService::track_memory_usage(); 3998 3999 // In prepare_for_verify() below we'll need to scan the deferred 4000 // update buffers to bring the RSets up-to-date if 4001 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning 4002 // the update buffers we'll probably need to scan cards on the 4003 // regions we just allocated to (i.e., the GC alloc 4004 // regions). However, during the last GC we called 4005 // set_saved_mark() on all the GC alloc regions, so card 4006 // scanning might skip the [saved_mark_word()...top()] area of 4007 // those regions (i.e., the area we allocated objects into 4008 // during the last GC). But it shouldn't. Given that 4009 // saved_mark_word() is conditional on whether the GC time stamp 4010 // on the region is current or not, by incrementing the GC time 4011 // stamp here we invalidate all the GC time stamps on all the 4012 // regions and saved_mark_word() will simply return top() for 4013 // all the regions. This is a nicer way of ensuring this rather 4014 // than iterating over the regions and fixing them. In fact, the 4015 // GC time stamp increment here also ensures that 4016 // saved_mark_word() will return top() between pauses, i.e., 4017 // during concurrent refinement. So we don't need the 4018 // is_gc_active() check to decided which top to use when 4019 // scanning cards (see CR 7039627). 4020 increment_gc_time_stamp(); 4021 4022 verify_after_gc(); 4023 check_bitmaps("GC End"); 4024 4025 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 4026 ref_processor_stw()->verify_no_references_recorded(); 4027 4028 // CM reference discovery will be re-enabled if necessary. 4029 } 4030 4031 // We should do this after we potentially expand the heap so 4032 // that all the COMMIT events are generated before the end GC 4033 // event, and after we retire the GC alloc regions so that all 4034 // RETIRE events are generated before the end GC event. 4035 _hr_printer.end_gc(false /* full */, (size_t) total_collections()); 4036 4037 #ifdef TRACESPINNING 4038 ParallelTaskTerminator::print_termination_counts(); 4039 #endif 4040 4041 gc_epilogue(false); 4042 } 4043 4044 // Print the remainder of the GC log output. 4045 log_gc_footer(os::elapsedTime() - pause_start_sec); 4046 4047 // It is not yet to safe to tell the concurrent mark to 4048 // start as we have some optional output below. We don't want the 4049 // output from the concurrent mark thread interfering with this 4050 // logging output either. 4051 4052 _hrm.verify_optional(); 4053 verify_region_sets_optional(); 4054 4055 TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats()); 4056 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); 4057 4058 print_heap_after_gc(); 4059 trace_heap_after_gc(_gc_tracer_stw); 4060 4061 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 4062 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 4063 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 4064 // before any GC notifications are raised. 4065 g1mm()->update_sizes(); 4066 4067 _gc_tracer_stw->report_evacuation_info(&evacuation_info); 4068 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold()); 4069 _gc_timer_stw->register_gc_end(); 4070 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions()); 4071 } 4072 // It should now be safe to tell the concurrent mark thread to start 4073 // without its logging output interfering with the logging output 4074 // that came from the pause. 4075 4076 if (should_start_conc_mark) { 4077 // CAUTION: after the doConcurrentMark() call below, 4078 // the concurrent marking thread(s) could be running 4079 // concurrently with us. Make sure that anything after 4080 // this point does not assume that we are the only GC thread 4081 // running. Note: of course, the actual marking work will 4082 // not start until the safepoint itself is released in 4083 // SuspendibleThreadSet::desynchronize(). 4084 doConcurrentMark(); 4085 } 4086 4087 return true; 4088 } 4089 4090 void G1CollectedHeap::remove_self_forwarding_pointers() { 4091 double remove_self_forwards_start = os::elapsedTime(); 4092 4093 G1ParRemoveSelfForwardPtrsTask rsfp_task; 4094 workers()->run_task(&rsfp_task); 4095 4096 // Now restore saved marks, if any. 4097 for (uint i = 0; i < ParallelGCThreads; i++) { 4098 OopAndMarkOopStack& cur = _preserved_objs[i]; 4099 while (!cur.is_empty()) { 4100 OopAndMarkOop elem = cur.pop(); 4101 elem.set_mark(); 4102 } 4103 cur.clear(true); 4104 } 4105 4106 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0); 4107 } 4108 4109 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) { 4110 if (!_evacuation_failed) { 4111 _evacuation_failed = true; 4112 } 4113 4114 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size()); 4115 4116 // We want to call the "for_promotion_failure" version only in the 4117 // case of a promotion failure. 4118 if (m->must_be_preserved_for_promotion_failure(obj)) { 4119 OopAndMarkOop elem(obj, m); 4120 _preserved_objs[worker_id].push(elem); 4121 } 4122 } 4123 4124 class G1ParEvacuateFollowersClosure : public VoidClosure { 4125 private: 4126 double _start_term; 4127 double _term_time; 4128 size_t _term_attempts; 4129 4130 void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); } 4131 void end_term_time() { _term_time += os::elapsedTime() - _start_term; } 4132 protected: 4133 G1CollectedHeap* _g1h; 4134 G1ParScanThreadState* _par_scan_state; 4135 RefToScanQueueSet* _queues; 4136 ParallelTaskTerminator* _terminator; 4137 4138 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 4139 RefToScanQueueSet* queues() { return _queues; } 4140 ParallelTaskTerminator* terminator() { return _terminator; } 4141 4142 public: 4143 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h, 4144 G1ParScanThreadState* par_scan_state, 4145 RefToScanQueueSet* queues, 4146 ParallelTaskTerminator* terminator) 4147 : _g1h(g1h), _par_scan_state(par_scan_state), 4148 _queues(queues), _terminator(terminator), 4149 _start_term(0.0), _term_time(0.0), _term_attempts(0) {} 4150 4151 void do_void(); 4152 4153 double term_time() const { return _term_time; } 4154 size_t term_attempts() const { return _term_attempts; } 4155 4156 private: 4157 inline bool offer_termination(); 4158 }; 4159 4160 bool G1ParEvacuateFollowersClosure::offer_termination() { 4161 G1ParScanThreadState* const pss = par_scan_state(); 4162 start_term_time(); 4163 const bool res = terminator()->offer_termination(); 4164 end_term_time(); 4165 return res; 4166 } 4167 4168 void G1ParEvacuateFollowersClosure::do_void() { 4169 G1ParScanThreadState* const pss = par_scan_state(); 4170 pss->trim_queue(); 4171 do { 4172 pss->steal_and_trim_queue(queues()); 4173 } while (!offer_termination()); 4174 } 4175 4176 class G1ParTask : public AbstractGangTask { 4177 protected: 4178 G1CollectedHeap* _g1h; 4179 G1ParScanThreadStateSet* _pss; 4180 RefToScanQueueSet* _queues; 4181 G1RootProcessor* _root_processor; 4182 ParallelTaskTerminator _terminator; 4183 uint _n_workers; 4184 4185 public: 4186 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers) 4187 : AbstractGangTask("G1 collection"), 4188 _g1h(g1h), 4189 _pss(per_thread_states), 4190 _queues(task_queues), 4191 _root_processor(root_processor), 4192 _terminator(n_workers, _queues), 4193 _n_workers(n_workers) 4194 {} 4195 4196 void work(uint worker_id) { 4197 if (worker_id >= _n_workers) return; // no work needed this round 4198 4199 double start_sec = os::elapsedTime(); 4200 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec); 4201 4202 { 4203 ResourceMark rm; 4204 HandleMark hm; 4205 4206 ReferenceProcessor* rp = _g1h->ref_processor_stw(); 4207 4208 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 4209 pss->set_ref_processor(rp); 4210 4211 double start_strong_roots_sec = os::elapsedTime(); 4212 4213 _root_processor->evacuate_roots(pss->closures(), worker_id); 4214 4215 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, pss); 4216 4217 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid 4218 // treating the nmethods visited to act as roots for concurrent marking. 4219 // We only want to make sure that the oops in the nmethods are adjusted with regard to the 4220 // objects copied by the current evacuation. 4221 size_t cards_scanned = _g1h->g1_rem_set()->oops_into_collection_set_do(&push_heap_rs_cl, 4222 pss->closures()->weak_codeblobs(), 4223 worker_id); 4224 4225 _pss->add_cards_scanned(worker_id, cards_scanned); 4226 4227 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec; 4228 4229 double term_sec = 0.0; 4230 size_t evac_term_attempts = 0; 4231 { 4232 double start = os::elapsedTime(); 4233 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator); 4234 evac.do_void(); 4235 4236 evac_term_attempts = evac.term_attempts(); 4237 term_sec = evac.term_time(); 4238 double elapsed_sec = os::elapsedTime() - start; 4239 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec); 4240 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec); 4241 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts); 4242 } 4243 4244 assert(pss->queue_is_empty(), "should be empty"); 4245 4246 if (PrintTerminationStats) { 4247 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); 4248 size_t lab_waste; 4249 size_t lab_undo_waste; 4250 pss->waste(lab_waste, lab_undo_waste); 4251 _g1h->print_termination_stats(gclog_or_tty, 4252 worker_id, 4253 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */ 4254 strong_roots_sec * 1000.0, /* strong roots time */ 4255 term_sec * 1000.0, /* evac term time */ 4256 evac_term_attempts, /* evac term attempts */ 4257 lab_waste, /* alloc buffer waste */ 4258 lab_undo_waste /* undo waste */ 4259 ); 4260 } 4261 4262 // Close the inner scope so that the ResourceMark and HandleMark 4263 // destructors are executed here and are included as part of the 4264 // "GC Worker Time". 4265 } 4266 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime()); 4267 } 4268 }; 4269 4270 void G1CollectedHeap::print_termination_stats_hdr(outputStream* const st) { 4271 st->print_raw_cr("GC Termination Stats"); 4272 st->print_raw_cr(" elapsed --strong roots-- -------termination------- ------waste (KiB)------"); 4273 st->print_raw_cr("thr ms ms % ms % attempts total alloc undo"); 4274 st->print_raw_cr("--- --------- --------- ------ --------- ------ -------- ------- ------- -------"); 4275 } 4276 4277 void G1CollectedHeap::print_termination_stats(outputStream* const st, 4278 uint worker_id, 4279 double elapsed_ms, 4280 double strong_roots_ms, 4281 double term_ms, 4282 size_t term_attempts, 4283 size_t alloc_buffer_waste, 4284 size_t undo_waste) const { 4285 st->print_cr("%3d %9.2f %9.2f %6.2f " 4286 "%9.2f %6.2f " SIZE_FORMAT_W(8) " " 4287 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7), 4288 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms, 4289 term_ms, term_ms * 100 / elapsed_ms, term_attempts, 4290 (alloc_buffer_waste + undo_waste) * HeapWordSize / K, 4291 alloc_buffer_waste * HeapWordSize / K, 4292 undo_waste * HeapWordSize / K); 4293 } 4294 4295 class G1StringSymbolTableUnlinkTask : public AbstractGangTask { 4296 private: 4297 BoolObjectClosure* _is_alive; 4298 int _initial_string_table_size; 4299 int _initial_symbol_table_size; 4300 4301 bool _process_strings; 4302 int _strings_processed; 4303 int _strings_removed; 4304 4305 bool _process_symbols; 4306 int _symbols_processed; 4307 int _symbols_removed; 4308 4309 public: 4310 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) : 4311 AbstractGangTask("String/Symbol Unlinking"), 4312 _is_alive(is_alive), 4313 _process_strings(process_strings), _strings_processed(0), _strings_removed(0), 4314 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) { 4315 4316 _initial_string_table_size = StringTable::the_table()->table_size(); 4317 _initial_symbol_table_size = SymbolTable::the_table()->table_size(); 4318 if (process_strings) { 4319 StringTable::clear_parallel_claimed_index(); 4320 } 4321 if (process_symbols) { 4322 SymbolTable::clear_parallel_claimed_index(); 4323 } 4324 } 4325 4326 ~G1StringSymbolTableUnlinkTask() { 4327 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size, 4328 "claim value %d after unlink less than initial string table size %d", 4329 StringTable::parallel_claimed_index(), _initial_string_table_size); 4330 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size, 4331 "claim value %d after unlink less than initial symbol table size %d", 4332 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size); 4333 4334 if (G1TraceStringSymbolTableScrubbing) { 4335 gclog_or_tty->print_cr("Cleaned string and symbol table, " 4336 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, " 4337 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed", 4338 strings_processed(), strings_removed(), 4339 symbols_processed(), symbols_removed()); 4340 } 4341 } 4342 4343 void work(uint worker_id) { 4344 int strings_processed = 0; 4345 int strings_removed = 0; 4346 int symbols_processed = 0; 4347 int symbols_removed = 0; 4348 if (_process_strings) { 4349 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed); 4350 Atomic::add(strings_processed, &_strings_processed); 4351 Atomic::add(strings_removed, &_strings_removed); 4352 } 4353 if (_process_symbols) { 4354 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed); 4355 Atomic::add(symbols_processed, &_symbols_processed); 4356 Atomic::add(symbols_removed, &_symbols_removed); 4357 } 4358 } 4359 4360 size_t strings_processed() const { return (size_t)_strings_processed; } 4361 size_t strings_removed() const { return (size_t)_strings_removed; } 4362 4363 size_t symbols_processed() const { return (size_t)_symbols_processed; } 4364 size_t symbols_removed() const { return (size_t)_symbols_removed; } 4365 }; 4366 4367 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC { 4368 private: 4369 static Monitor* _lock; 4370 4371 BoolObjectClosure* const _is_alive; 4372 const bool _unloading_occurred; 4373 const uint _num_workers; 4374 4375 // Variables used to claim nmethods. 4376 nmethod* _first_nmethod; 4377 volatile nmethod* _claimed_nmethod; 4378 4379 // The list of nmethods that need to be processed by the second pass. 4380 volatile nmethod* _postponed_list; 4381 volatile uint _num_entered_barrier; 4382 4383 public: 4384 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) : 4385 _is_alive(is_alive), 4386 _unloading_occurred(unloading_occurred), 4387 _num_workers(num_workers), 4388 _first_nmethod(NULL), 4389 _claimed_nmethod(NULL), 4390 _postponed_list(NULL), 4391 _num_entered_barrier(0) 4392 { 4393 nmethod::increase_unloading_clock(); 4394 // Get first alive nmethod 4395 NMethodIterator iter = NMethodIterator(); 4396 if(iter.next_alive()) { 4397 _first_nmethod = iter.method(); 4398 } 4399 _claimed_nmethod = (volatile nmethod*)_first_nmethod; 4400 } 4401 4402 ~G1CodeCacheUnloadingTask() { 4403 CodeCache::verify_clean_inline_caches(); 4404 4405 CodeCache::set_needs_cache_clean(false); 4406 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be"); 4407 4408 CodeCache::verify_icholder_relocations(); 4409 } 4410 4411 private: 4412 void add_to_postponed_list(nmethod* nm) { 4413 nmethod* old; 4414 do { 4415 old = (nmethod*)_postponed_list; 4416 nm->set_unloading_next(old); 4417 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old); 4418 } 4419 4420 void clean_nmethod(nmethod* nm) { 4421 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred); 4422 4423 if (postponed) { 4424 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet. 4425 add_to_postponed_list(nm); 4426 } 4427 4428 // Mark that this thread has been cleaned/unloaded. 4429 // After this call, it will be safe to ask if this nmethod was unloaded or not. 4430 nm->set_unloading_clock(nmethod::global_unloading_clock()); 4431 } 4432 4433 void clean_nmethod_postponed(nmethod* nm) { 4434 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred); 4435 } 4436 4437 static const int MaxClaimNmethods = 16; 4438 4439 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) { 4440 nmethod* first; 4441 NMethodIterator last; 4442 4443 do { 4444 *num_claimed_nmethods = 0; 4445 4446 first = (nmethod*)_claimed_nmethod; 4447 last = NMethodIterator(first); 4448 4449 if (first != NULL) { 4450 4451 for (int i = 0; i < MaxClaimNmethods; i++) { 4452 if (!last.next_alive()) { 4453 break; 4454 } 4455 claimed_nmethods[i] = last.method(); 4456 (*num_claimed_nmethods)++; 4457 } 4458 } 4459 4460 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first); 4461 } 4462 4463 nmethod* claim_postponed_nmethod() { 4464 nmethod* claim; 4465 nmethod* next; 4466 4467 do { 4468 claim = (nmethod*)_postponed_list; 4469 if (claim == NULL) { 4470 return NULL; 4471 } 4472 4473 next = claim->unloading_next(); 4474 4475 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim); 4476 4477 return claim; 4478 } 4479 4480 public: 4481 // Mark that we're done with the first pass of nmethod cleaning. 4482 void barrier_mark(uint worker_id) { 4483 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 4484 _num_entered_barrier++; 4485 if (_num_entered_barrier == _num_workers) { 4486 ml.notify_all(); 4487 } 4488 } 4489 4490 // See if we have to wait for the other workers to 4491 // finish their first-pass nmethod cleaning work. 4492 void barrier_wait(uint worker_id) { 4493 if (_num_entered_barrier < _num_workers) { 4494 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 4495 while (_num_entered_barrier < _num_workers) { 4496 ml.wait(Mutex::_no_safepoint_check_flag, 0, false); 4497 } 4498 } 4499 } 4500 4501 // Cleaning and unloading of nmethods. Some work has to be postponed 4502 // to the second pass, when we know which nmethods survive. 4503 void work_first_pass(uint worker_id) { 4504 // The first nmethods is claimed by the first worker. 4505 if (worker_id == 0 && _first_nmethod != NULL) { 4506 clean_nmethod(_first_nmethod); 4507 _first_nmethod = NULL; 4508 } 4509 4510 int num_claimed_nmethods; 4511 nmethod* claimed_nmethods[MaxClaimNmethods]; 4512 4513 while (true) { 4514 claim_nmethods(claimed_nmethods, &num_claimed_nmethods); 4515 4516 if (num_claimed_nmethods == 0) { 4517 break; 4518 } 4519 4520 for (int i = 0; i < num_claimed_nmethods; i++) { 4521 clean_nmethod(claimed_nmethods[i]); 4522 } 4523 } 4524 } 4525 4526 void work_second_pass(uint worker_id) { 4527 nmethod* nm; 4528 // Take care of postponed nmethods. 4529 while ((nm = claim_postponed_nmethod()) != NULL) { 4530 clean_nmethod_postponed(nm); 4531 } 4532 } 4533 }; 4534 4535 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never); 4536 4537 class G1KlassCleaningTask : public StackObj { 4538 BoolObjectClosure* _is_alive; 4539 volatile jint _clean_klass_tree_claimed; 4540 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator; 4541 4542 public: 4543 G1KlassCleaningTask(BoolObjectClosure* is_alive) : 4544 _is_alive(is_alive), 4545 _clean_klass_tree_claimed(0), 4546 _klass_iterator() { 4547 } 4548 4549 private: 4550 bool claim_clean_klass_tree_task() { 4551 if (_clean_klass_tree_claimed) { 4552 return false; 4553 } 4554 4555 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0; 4556 } 4557 4558 InstanceKlass* claim_next_klass() { 4559 Klass* klass; 4560 do { 4561 klass =_klass_iterator.next_klass(); 4562 } while (klass != NULL && !klass->is_instance_klass()); 4563 4564 // this can be null so don't call InstanceKlass::cast 4565 return static_cast<InstanceKlass*>(klass); 4566 } 4567 4568 public: 4569 4570 void clean_klass(InstanceKlass* ik) { 4571 ik->clean_weak_instanceklass_links(_is_alive); 4572 } 4573 4574 void work() { 4575 ResourceMark rm; 4576 4577 // One worker will clean the subklass/sibling klass tree. 4578 if (claim_clean_klass_tree_task()) { 4579 Klass::clean_subklass_tree(_is_alive); 4580 } 4581 4582 // All workers will help cleaning the classes, 4583 InstanceKlass* klass; 4584 while ((klass = claim_next_klass()) != NULL) { 4585 clean_klass(klass); 4586 } 4587 } 4588 }; 4589 4590 // To minimize the remark pause times, the tasks below are done in parallel. 4591 class G1ParallelCleaningTask : public AbstractGangTask { 4592 private: 4593 G1StringSymbolTableUnlinkTask _string_symbol_task; 4594 G1CodeCacheUnloadingTask _code_cache_task; 4595 G1KlassCleaningTask _klass_cleaning_task; 4596 4597 public: 4598 // The constructor is run in the VMThread. 4599 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) : 4600 AbstractGangTask("Parallel Cleaning"), 4601 _string_symbol_task(is_alive, process_strings, process_symbols), 4602 _code_cache_task(num_workers, is_alive, unloading_occurred), 4603 _klass_cleaning_task(is_alive) { 4604 } 4605 4606 // The parallel work done by all worker threads. 4607 void work(uint worker_id) { 4608 // Do first pass of code cache cleaning. 4609 _code_cache_task.work_first_pass(worker_id); 4610 4611 // Let the threads mark that the first pass is done. 4612 _code_cache_task.barrier_mark(worker_id); 4613 4614 // Clean the Strings and Symbols. 4615 _string_symbol_task.work(worker_id); 4616 4617 // Wait for all workers to finish the first code cache cleaning pass. 4618 _code_cache_task.barrier_wait(worker_id); 4619 4620 // Do the second code cache cleaning work, which realize on 4621 // the liveness information gathered during the first pass. 4622 _code_cache_task.work_second_pass(worker_id); 4623 4624 // Clean all klasses that were not unloaded. 4625 _klass_cleaning_task.work(); 4626 } 4627 }; 4628 4629 4630 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive, 4631 bool process_strings, 4632 bool process_symbols, 4633 bool class_unloading_occurred) { 4634 uint n_workers = workers()->active_workers(); 4635 4636 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, 4637 n_workers, class_unloading_occurred); 4638 workers()->run_task(&g1_unlink_task); 4639 } 4640 4641 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive, 4642 bool process_strings, bool process_symbols) { 4643 { 4644 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols); 4645 workers()->run_task(&g1_unlink_task); 4646 } 4647 4648 if (G1StringDedup::is_enabled()) { 4649 G1StringDedup::unlink(is_alive); 4650 } 4651 } 4652 4653 class G1RedirtyLoggedCardsTask : public AbstractGangTask { 4654 private: 4655 DirtyCardQueueSet* _queue; 4656 public: 4657 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { } 4658 4659 virtual void work(uint worker_id) { 4660 G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times(); 4661 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id); 4662 4663 RedirtyLoggedCardTableEntryClosure cl; 4664 _queue->par_apply_closure_to_all_completed_buffers(&cl); 4665 4666 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed()); 4667 } 4668 }; 4669 4670 void G1CollectedHeap::redirty_logged_cards() { 4671 double redirty_logged_cards_start = os::elapsedTime(); 4672 4673 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set()); 4674 dirty_card_queue_set().reset_for_par_iteration(); 4675 workers()->run_task(&redirty_task); 4676 4677 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set(); 4678 dcq.merge_bufferlists(&dirty_card_queue_set()); 4679 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed"); 4680 4681 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0); 4682 } 4683 4684 // Weak Reference Processing support 4685 4686 // An always "is_alive" closure that is used to preserve referents. 4687 // If the object is non-null then it's alive. Used in the preservation 4688 // of referent objects that are pointed to by reference objects 4689 // discovered by the CM ref processor. 4690 class G1AlwaysAliveClosure: public BoolObjectClosure { 4691 G1CollectedHeap* _g1; 4692 public: 4693 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 4694 bool do_object_b(oop p) { 4695 if (p != NULL) { 4696 return true; 4697 } 4698 return false; 4699 } 4700 }; 4701 4702 bool G1STWIsAliveClosure::do_object_b(oop p) { 4703 // An object is reachable if it is outside the collection set, 4704 // or is inside and copied. 4705 return !_g1->is_in_cset(p) || p->is_forwarded(); 4706 } 4707 4708 // Non Copying Keep Alive closure 4709 class G1KeepAliveClosure: public OopClosure { 4710 G1CollectedHeap* _g1; 4711 public: 4712 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 4713 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } 4714 void do_oop(oop* p) { 4715 oop obj = *p; 4716 assert(obj != NULL, "the caller should have filtered out NULL values"); 4717 4718 const InCSetState cset_state = _g1->in_cset_state(obj); 4719 if (!cset_state.is_in_cset_or_humongous()) { 4720 return; 4721 } 4722 if (cset_state.is_in_cset()) { 4723 assert( obj->is_forwarded(), "invariant" ); 4724 *p = obj->forwardee(); 4725 } else { 4726 assert(!obj->is_forwarded(), "invariant" ); 4727 assert(cset_state.is_humongous(), 4728 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value()); 4729 _g1->set_humongous_is_live(obj); 4730 } 4731 } 4732 }; 4733 4734 // Copying Keep Alive closure - can be called from both 4735 // serial and parallel code as long as different worker 4736 // threads utilize different G1ParScanThreadState instances 4737 // and different queues. 4738 4739 class G1CopyingKeepAliveClosure: public OopClosure { 4740 G1CollectedHeap* _g1h; 4741 OopClosure* _copy_non_heap_obj_cl; 4742 G1ParScanThreadState* _par_scan_state; 4743 4744 public: 4745 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, 4746 OopClosure* non_heap_obj_cl, 4747 G1ParScanThreadState* pss): 4748 _g1h(g1h), 4749 _copy_non_heap_obj_cl(non_heap_obj_cl), 4750 _par_scan_state(pss) 4751 {} 4752 4753 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 4754 virtual void do_oop( oop* p) { do_oop_work(p); } 4755 4756 template <class T> void do_oop_work(T* p) { 4757 oop obj = oopDesc::load_decode_heap_oop(p); 4758 4759 if (_g1h->is_in_cset_or_humongous(obj)) { 4760 // If the referent object has been forwarded (either copied 4761 // to a new location or to itself in the event of an 4762 // evacuation failure) then we need to update the reference 4763 // field and, if both reference and referent are in the G1 4764 // heap, update the RSet for the referent. 4765 // 4766 // If the referent has not been forwarded then we have to keep 4767 // it alive by policy. Therefore we have copy the referent. 4768 // 4769 // If the reference field is in the G1 heap then we can push 4770 // on the PSS queue. When the queue is drained (after each 4771 // phase of reference processing) the object and it's followers 4772 // will be copied, the reference field set to point to the 4773 // new location, and the RSet updated. Otherwise we need to 4774 // use the the non-heap or metadata closures directly to copy 4775 // the referent object and update the pointer, while avoiding 4776 // updating the RSet. 4777 4778 if (_g1h->is_in_g1_reserved(p)) { 4779 _par_scan_state->push_on_queue(p); 4780 } else { 4781 assert(!Metaspace::contains((const void*)p), 4782 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p)); 4783 _copy_non_heap_obj_cl->do_oop(p); 4784 } 4785 } 4786 } 4787 }; 4788 4789 // Serial drain queue closure. Called as the 'complete_gc' 4790 // closure for each discovered list in some of the 4791 // reference processing phases. 4792 4793 class G1STWDrainQueueClosure: public VoidClosure { 4794 protected: 4795 G1CollectedHeap* _g1h; 4796 G1ParScanThreadState* _par_scan_state; 4797 4798 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 4799 4800 public: 4801 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : 4802 _g1h(g1h), 4803 _par_scan_state(pss) 4804 { } 4805 4806 void do_void() { 4807 G1ParScanThreadState* const pss = par_scan_state(); 4808 pss->trim_queue(); 4809 } 4810 }; 4811 4812 // Parallel Reference Processing closures 4813 4814 // Implementation of AbstractRefProcTaskExecutor for parallel reference 4815 // processing during G1 evacuation pauses. 4816 4817 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 4818 private: 4819 G1CollectedHeap* _g1h; 4820 G1ParScanThreadStateSet* _pss; 4821 RefToScanQueueSet* _queues; 4822 WorkGang* _workers; 4823 uint _active_workers; 4824 4825 public: 4826 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, 4827 G1ParScanThreadStateSet* per_thread_states, 4828 WorkGang* workers, 4829 RefToScanQueueSet *task_queues, 4830 uint n_workers) : 4831 _g1h(g1h), 4832 _pss(per_thread_states), 4833 _queues(task_queues), 4834 _workers(workers), 4835 _active_workers(n_workers) 4836 { 4837 assert(n_workers > 0, "shouldn't call this otherwise"); 4838 } 4839 4840 // Executes the given task using concurrent marking worker threads. 4841 virtual void execute(ProcessTask& task); 4842 virtual void execute(EnqueueTask& task); 4843 }; 4844 4845 // Gang task for possibly parallel reference processing 4846 4847 class G1STWRefProcTaskProxy: public AbstractGangTask { 4848 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 4849 ProcessTask& _proc_task; 4850 G1CollectedHeap* _g1h; 4851 G1ParScanThreadStateSet* _pss; 4852 RefToScanQueueSet* _task_queues; 4853 ParallelTaskTerminator* _terminator; 4854 4855 public: 4856 G1STWRefProcTaskProxy(ProcessTask& proc_task, 4857 G1CollectedHeap* g1h, 4858 G1ParScanThreadStateSet* per_thread_states, 4859 RefToScanQueueSet *task_queues, 4860 ParallelTaskTerminator* terminator) : 4861 AbstractGangTask("Process reference objects in parallel"), 4862 _proc_task(proc_task), 4863 _g1h(g1h), 4864 _pss(per_thread_states), 4865 _task_queues(task_queues), 4866 _terminator(terminator) 4867 {} 4868 4869 virtual void work(uint worker_id) { 4870 // The reference processing task executed by a single worker. 4871 ResourceMark rm; 4872 HandleMark hm; 4873 4874 G1STWIsAliveClosure is_alive(_g1h); 4875 4876 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 4877 pss->set_ref_processor(NULL); 4878 4879 // Keep alive closure. 4880 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss); 4881 4882 // Complete GC closure 4883 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator); 4884 4885 // Call the reference processing task's work routine. 4886 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); 4887 4888 // Note we cannot assert that the refs array is empty here as not all 4889 // of the processing tasks (specifically phase2 - pp2_work) execute 4890 // the complete_gc closure (which ordinarily would drain the queue) so 4891 // the queue may not be empty. 4892 } 4893 }; 4894 4895 // Driver routine for parallel reference processing. 4896 // Creates an instance of the ref processing gang 4897 // task and has the worker threads execute it. 4898 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) { 4899 assert(_workers != NULL, "Need parallel worker threads."); 4900 4901 ParallelTaskTerminator terminator(_active_workers, _queues); 4902 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator); 4903 4904 _workers->run_task(&proc_task_proxy); 4905 } 4906 4907 // Gang task for parallel reference enqueueing. 4908 4909 class G1STWRefEnqueueTaskProxy: public AbstractGangTask { 4910 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; 4911 EnqueueTask& _enq_task; 4912 4913 public: 4914 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) : 4915 AbstractGangTask("Enqueue reference objects in parallel"), 4916 _enq_task(enq_task) 4917 { } 4918 4919 virtual void work(uint worker_id) { 4920 _enq_task.work(worker_id); 4921 } 4922 }; 4923 4924 // Driver routine for parallel reference enqueueing. 4925 // Creates an instance of the ref enqueueing gang 4926 // task and has the worker threads execute it. 4927 4928 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) { 4929 assert(_workers != NULL, "Need parallel worker threads."); 4930 4931 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task); 4932 4933 _workers->run_task(&enq_task_proxy); 4934 } 4935 4936 // End of weak reference support closures 4937 4938 // Abstract task used to preserve (i.e. copy) any referent objects 4939 // that are in the collection set and are pointed to by reference 4940 // objects discovered by the CM ref processor. 4941 4942 class G1ParPreserveCMReferentsTask: public AbstractGangTask { 4943 protected: 4944 G1CollectedHeap* _g1h; 4945 G1ParScanThreadStateSet* _pss; 4946 RefToScanQueueSet* _queues; 4947 ParallelTaskTerminator _terminator; 4948 uint _n_workers; 4949 4950 public: 4951 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) : 4952 AbstractGangTask("ParPreserveCMReferents"), 4953 _g1h(g1h), 4954 _pss(per_thread_states), 4955 _queues(task_queues), 4956 _terminator(workers, _queues), 4957 _n_workers(workers) 4958 { } 4959 4960 void work(uint worker_id) { 4961 ResourceMark rm; 4962 HandleMark hm; 4963 4964 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 4965 pss->set_ref_processor(NULL); 4966 assert(pss->queue_is_empty(), "both queue and overflow should be empty"); 4967 4968 // Is alive closure 4969 G1AlwaysAliveClosure always_alive(_g1h); 4970 4971 // Copying keep alive closure. Applied to referent objects that need 4972 // to be copied. 4973 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss); 4974 4975 ReferenceProcessor* rp = _g1h->ref_processor_cm(); 4976 4977 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q(); 4978 uint stride = MIN2(MAX2(_n_workers, 1U), limit); 4979 4980 // limit is set using max_num_q() - which was set using ParallelGCThreads. 4981 // So this must be true - but assert just in case someone decides to 4982 // change the worker ids. 4983 assert(worker_id < limit, "sanity"); 4984 assert(!rp->discovery_is_atomic(), "check this code"); 4985 4986 // Select discovered lists [i, i+stride, i+2*stride,...,limit) 4987 for (uint idx = worker_id; idx < limit; idx += stride) { 4988 DiscoveredList& ref_list = rp->discovered_refs()[idx]; 4989 4990 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive); 4991 while (iter.has_next()) { 4992 // Since discovery is not atomic for the CM ref processor, we 4993 // can see some null referent objects. 4994 iter.load_ptrs(DEBUG_ONLY(true)); 4995 oop ref = iter.obj(); 4996 4997 // This will filter nulls. 4998 if (iter.is_referent_alive()) { 4999 iter.make_referent_alive(); 5000 } 5001 iter.move_to_next(); 5002 } 5003 } 5004 5005 // Drain the queue - which may cause stealing 5006 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator); 5007 drain_queue.do_void(); 5008 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure 5009 assert(pss->queue_is_empty(), "should be"); 5010 } 5011 }; 5012 5013 // Weak Reference processing during an evacuation pause (part 1). 5014 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) { 5015 double ref_proc_start = os::elapsedTime(); 5016 5017 ReferenceProcessor* rp = _ref_processor_stw; 5018 assert(rp->discovery_enabled(), "should have been enabled"); 5019 5020 // Any reference objects, in the collection set, that were 'discovered' 5021 // by the CM ref processor should have already been copied (either by 5022 // applying the external root copy closure to the discovered lists, or 5023 // by following an RSet entry). 5024 // 5025 // But some of the referents, that are in the collection set, that these 5026 // reference objects point to may not have been copied: the STW ref 5027 // processor would have seen that the reference object had already 5028 // been 'discovered' and would have skipped discovering the reference, 5029 // but would not have treated the reference object as a regular oop. 5030 // As a result the copy closure would not have been applied to the 5031 // referent object. 5032 // 5033 // We need to explicitly copy these referent objects - the references 5034 // will be processed at the end of remarking. 5035 // 5036 // We also need to do this copying before we process the reference 5037 // objects discovered by the STW ref processor in case one of these 5038 // referents points to another object which is also referenced by an 5039 // object discovered by the STW ref processor. 5040 5041 uint no_of_gc_workers = workers()->active_workers(); 5042 5043 G1ParPreserveCMReferentsTask keep_cm_referents(this, 5044 per_thread_states, 5045 no_of_gc_workers, 5046 _task_queues); 5047 5048 workers()->run_task(&keep_cm_referents); 5049 5050 // Closure to test whether a referent is alive. 5051 G1STWIsAliveClosure is_alive(this); 5052 5053 // Even when parallel reference processing is enabled, the processing 5054 // of JNI refs is serial and performed serially by the current thread 5055 // rather than by a worker. The following PSS will be used for processing 5056 // JNI refs. 5057 5058 // Use only a single queue for this PSS. 5059 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0); 5060 pss->set_ref_processor(NULL); 5061 assert(pss->queue_is_empty(), "pre-condition"); 5062 5063 // Keep alive closure. 5064 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss); 5065 5066 // Serial Complete GC closure 5067 G1STWDrainQueueClosure drain_queue(this, pss); 5068 5069 // Setup the soft refs policy... 5070 rp->setup_policy(false); 5071 5072 ReferenceProcessorStats stats; 5073 if (!rp->processing_is_mt()) { 5074 // Serial reference processing... 5075 stats = rp->process_discovered_references(&is_alive, 5076 &keep_alive, 5077 &drain_queue, 5078 NULL, 5079 _gc_timer_stw); 5080 } else { 5081 // Parallel reference processing 5082 assert(rp->num_q() == no_of_gc_workers, "sanity"); 5083 assert(no_of_gc_workers <= rp->max_num_q(), "sanity"); 5084 5085 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers); 5086 stats = rp->process_discovered_references(&is_alive, 5087 &keep_alive, 5088 &drain_queue, 5089 &par_task_executor, 5090 _gc_timer_stw); 5091 } 5092 5093 _gc_tracer_stw->report_gc_reference_stats(stats); 5094 5095 // We have completed copying any necessary live referent objects. 5096 assert(pss->queue_is_empty(), "both queue and overflow should be empty"); 5097 5098 double ref_proc_time = os::elapsedTime() - ref_proc_start; 5099 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 5100 } 5101 5102 // Weak Reference processing during an evacuation pause (part 2). 5103 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) { 5104 double ref_enq_start = os::elapsedTime(); 5105 5106 ReferenceProcessor* rp = _ref_processor_stw; 5107 assert(!rp->discovery_enabled(), "should have been disabled as part of processing"); 5108 5109 // Now enqueue any remaining on the discovered lists on to 5110 // the pending list. 5111 if (!rp->processing_is_mt()) { 5112 // Serial reference processing... 5113 rp->enqueue_discovered_references(); 5114 } else { 5115 // Parallel reference enqueueing 5116 5117 uint n_workers = workers()->active_workers(); 5118 5119 assert(rp->num_q() == n_workers, "sanity"); 5120 assert(n_workers <= rp->max_num_q(), "sanity"); 5121 5122 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers); 5123 rp->enqueue_discovered_references(&par_task_executor); 5124 } 5125 5126 rp->verify_no_references_recorded(); 5127 assert(!rp->discovery_enabled(), "should have been disabled"); 5128 5129 // FIXME 5130 // CM's reference processing also cleans up the string and symbol tables. 5131 // Should we do that here also? We could, but it is a serial operation 5132 // and could significantly increase the pause time. 5133 5134 double ref_enq_time = os::elapsedTime() - ref_enq_start; 5135 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0); 5136 } 5137 5138 void G1CollectedHeap::pre_evacuate_collection_set() { 5139 _expand_heap_after_alloc_failure = true; 5140 _evacuation_failed = false; 5141 5142 // Disable the hot card cache. 5143 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 5144 hot_card_cache->reset_hot_cache_claimed_index(); 5145 hot_card_cache->set_use_cache(false); 5146 5147 } 5148 5149 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) { 5150 g1_rem_set()->prepare_for_oops_into_collection_set_do(); 5151 5152 // Should G1EvacuationFailureALot be in effect for this GC? 5153 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) 5154 5155 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty"); 5156 double start_par_time_sec = os::elapsedTime(); 5157 double end_par_time_sec; 5158 5159 { 5160 const uint n_workers = workers()->active_workers(); 5161 G1RootProcessor root_processor(this, n_workers); 5162 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers); 5163 // InitialMark needs claim bits to keep track of the marked-through CLDs. 5164 if (collector_state()->during_initial_mark_pause()) { 5165 ClassLoaderDataGraph::clear_claimed_marks(); 5166 } 5167 5168 // The individual threads will set their evac-failure closures. 5169 if (PrintTerminationStats) { 5170 print_termination_stats_hdr(gclog_or_tty); 5171 } 5172 5173 workers()->run_task(&g1_par_task); 5174 end_par_time_sec = os::elapsedTime(); 5175 5176 // Closing the inner scope will execute the destructor 5177 // for the G1RootProcessor object. We record the current 5178 // elapsed time before closing the scope so that time 5179 // taken for the destructor is NOT included in the 5180 // reported parallel time. 5181 } 5182 5183 G1GCPhaseTimes* phase_times = g1_policy()->phase_times(); 5184 5185 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0; 5186 phase_times->record_par_time(par_time_ms); 5187 5188 double code_root_fixup_time_ms = 5189 (os::elapsedTime() - end_par_time_sec) * 1000.0; 5190 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms); 5191 5192 // Process any discovered reference objects - we have 5193 // to do this _before_ we retire the GC alloc regions 5194 // as we may have to copy some 'reachable' referent 5195 // objects (and their reachable sub-graphs) that were 5196 // not copied during the pause. 5197 process_discovered_references(per_thread_states); 5198 5199 if (G1StringDedup::is_enabled()) { 5200 double fixup_start = os::elapsedTime(); 5201 5202 G1STWIsAliveClosure is_alive(this); 5203 G1KeepAliveClosure keep_alive(this); 5204 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times); 5205 5206 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0; 5207 phase_times->record_string_dedup_fixup_time(fixup_time_ms); 5208 } 5209 5210 g1_rem_set()->cleanup_after_oops_into_collection_set_do(); 5211 5212 if (evacuation_failed()) { 5213 remove_self_forwarding_pointers(); 5214 5215 // Reset the G1EvacuationFailureALot counters and flags 5216 // Note: the values are reset only when an actual 5217 // evacuation failure occurs. 5218 NOT_PRODUCT(reset_evacuation_should_fail();) 5219 } 5220 5221 // Enqueue any remaining references remaining on the STW 5222 // reference processor's discovered lists. We need to do 5223 // this after the card table is cleaned (and verified) as 5224 // the act of enqueueing entries on to the pending list 5225 // will log these updates (and dirty their associated 5226 // cards). We need these updates logged to update any 5227 // RSets. 5228 enqueue_discovered_references(per_thread_states); 5229 } 5230 5231 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) { 5232 _allocator->release_gc_alloc_regions(evacuation_info); 5233 5234 per_thread_states->flush(); 5235 5236 record_obj_copy_mem_stats(); 5237 5238 // Reset and re-enable the hot card cache. 5239 // Note the counts for the cards in the regions in the 5240 // collection set are reset when the collection set is freed. 5241 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 5242 hot_card_cache->reset_hot_cache(); 5243 hot_card_cache->set_use_cache(true); 5244 5245 purge_code_root_memory(); 5246 5247 redirty_logged_cards(); 5248 #if defined(COMPILER2) || INCLUDE_JVMCI 5249 DerivedPointerTable::update_pointers(); 5250 #endif 5251 } 5252 5253 void G1CollectedHeap::record_obj_copy_mem_stats() { 5254 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats), 5255 create_g1_evac_summary(&_old_evac_stats)); 5256 } 5257 5258 void G1CollectedHeap::free_region(HeapRegion* hr, 5259 FreeRegionList* free_list, 5260 bool par, 5261 bool locked) { 5262 assert(!hr->is_free(), "the region should not be free"); 5263 assert(!hr->is_empty(), "the region should not be empty"); 5264 assert(_hrm.is_available(hr->hrm_index()), "region should be committed"); 5265 assert(free_list != NULL, "pre-condition"); 5266 5267 if (G1VerifyBitmaps) { 5268 MemRegion mr(hr->bottom(), hr->end()); 5269 concurrent_mark()->clearRangePrevBitmap(mr); 5270 } 5271 5272 // Clear the card counts for this region. 5273 // Note: we only need to do this if the region is not young 5274 // (since we don't refine cards in young regions). 5275 if (!hr->is_young()) { 5276 _cg1r->hot_card_cache()->reset_card_counts(hr); 5277 } 5278 hr->hr_clear(par, true /* clear_space */, locked /* locked */); 5279 free_list->add_ordered(hr); 5280 } 5281 5282 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 5283 FreeRegionList* free_list, 5284 bool par) { 5285 assert(hr->is_humongous(), "this is only for humongous regions"); 5286 assert(free_list != NULL, "pre-condition"); 5287 hr->clear_humongous(); 5288 free_region(hr, free_list, par); 5289 } 5290 5291 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed, 5292 const HeapRegionSetCount& humongous_regions_removed) { 5293 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) { 5294 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 5295 _old_set.bulk_remove(old_regions_removed); 5296 _humongous_set.bulk_remove(humongous_regions_removed); 5297 } 5298 5299 } 5300 5301 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) { 5302 assert(list != NULL, "list can't be null"); 5303 if (!list->is_empty()) { 5304 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag); 5305 _hrm.insert_list_into_free_list(list); 5306 } 5307 } 5308 5309 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) { 5310 decrease_used(bytes); 5311 } 5312 5313 class G1ParCleanupCTTask : public AbstractGangTask { 5314 G1SATBCardTableModRefBS* _ct_bs; 5315 G1CollectedHeap* _g1h; 5316 HeapRegion* volatile _su_head; 5317 public: 5318 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs, 5319 G1CollectedHeap* g1h) : 5320 AbstractGangTask("G1 Par Cleanup CT Task"), 5321 _ct_bs(ct_bs), _g1h(g1h) { } 5322 5323 void work(uint worker_id) { 5324 HeapRegion* r; 5325 while (r = _g1h->pop_dirty_cards_region()) { 5326 clear_cards(r); 5327 } 5328 } 5329 5330 void clear_cards(HeapRegion* r) { 5331 // Cards of the survivors should have already been dirtied. 5332 if (!r->is_survivor()) { 5333 _ct_bs->clear(MemRegion(r->bottom(), r->end())); 5334 } 5335 } 5336 }; 5337 5338 #ifndef PRODUCT 5339 class G1VerifyCardTableCleanup: public HeapRegionClosure { 5340 G1CollectedHeap* _g1h; 5341 G1SATBCardTableModRefBS* _ct_bs; 5342 public: 5343 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs) 5344 : _g1h(g1h), _ct_bs(ct_bs) { } 5345 virtual bool doHeapRegion(HeapRegion* r) { 5346 if (r->is_survivor()) { 5347 _g1h->verify_dirty_region(r); 5348 } else { 5349 _g1h->verify_not_dirty_region(r); 5350 } 5351 return false; 5352 } 5353 }; 5354 5355 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) { 5356 // All of the region should be clean. 5357 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5358 MemRegion mr(hr->bottom(), hr->end()); 5359 ct_bs->verify_not_dirty_region(mr); 5360 } 5361 5362 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) { 5363 // We cannot guarantee that [bottom(),end()] is dirty. Threads 5364 // dirty allocated blocks as they allocate them. The thread that 5365 // retires each region and replaces it with a new one will do a 5366 // maximal allocation to fill in [pre_dummy_top(),end()] but will 5367 // not dirty that area (one less thing to have to do while holding 5368 // a lock). So we can only verify that [bottom(),pre_dummy_top()] 5369 // is dirty. 5370 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5371 MemRegion mr(hr->bottom(), hr->pre_dummy_top()); 5372 if (hr->is_young()) { 5373 ct_bs->verify_g1_young_region(mr); 5374 } else { 5375 ct_bs->verify_dirty_region(mr); 5376 } 5377 } 5378 5379 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) { 5380 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5381 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) { 5382 verify_dirty_region(hr); 5383 } 5384 } 5385 5386 void G1CollectedHeap::verify_dirty_young_regions() { 5387 verify_dirty_young_list(_young_list->first_region()); 5388 } 5389 5390 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap, 5391 HeapWord* tams, HeapWord* end) { 5392 guarantee(tams <= end, 5393 "tams: " PTR_FORMAT " end: " PTR_FORMAT, p2i(tams), p2i(end)); 5394 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end); 5395 if (result < end) { 5396 gclog_or_tty->cr(); 5397 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: " PTR_FORMAT, 5398 bitmap_name, p2i(result)); 5399 gclog_or_tty->print_cr("## %s tams: " PTR_FORMAT " end: " PTR_FORMAT, 5400 bitmap_name, p2i(tams), p2i(end)); 5401 return false; 5402 } 5403 return true; 5404 } 5405 5406 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) { 5407 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap(); 5408 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap(); 5409 5410 HeapWord* bottom = hr->bottom(); 5411 HeapWord* ptams = hr->prev_top_at_mark_start(); 5412 HeapWord* ntams = hr->next_top_at_mark_start(); 5413 HeapWord* end = hr->end(); 5414 5415 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end); 5416 5417 bool res_n = true; 5418 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window 5419 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap 5420 // if we happen to be in that state. 5421 if (collector_state()->mark_in_progress() || !_cmThread->in_progress()) { 5422 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end); 5423 } 5424 if (!res_p || !res_n) { 5425 gclog_or_tty->print_cr("#### Bitmap verification failed for " HR_FORMAT, 5426 HR_FORMAT_PARAMS(hr)); 5427 gclog_or_tty->print_cr("#### Caller: %s", caller); 5428 return false; 5429 } 5430 return true; 5431 } 5432 5433 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) { 5434 if (!G1VerifyBitmaps) return; 5435 5436 guarantee(verify_bitmaps(caller, hr), "bitmap verification"); 5437 } 5438 5439 class G1VerifyBitmapClosure : public HeapRegionClosure { 5440 private: 5441 const char* _caller; 5442 G1CollectedHeap* _g1h; 5443 bool _failures; 5444 5445 public: 5446 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) : 5447 _caller(caller), _g1h(g1h), _failures(false) { } 5448 5449 bool failures() { return _failures; } 5450 5451 virtual bool doHeapRegion(HeapRegion* hr) { 5452 bool result = _g1h->verify_bitmaps(_caller, hr); 5453 if (!result) { 5454 _failures = true; 5455 } 5456 return false; 5457 } 5458 }; 5459 5460 void G1CollectedHeap::check_bitmaps(const char* caller) { 5461 if (!G1VerifyBitmaps) return; 5462 5463 G1VerifyBitmapClosure cl(caller, this); 5464 heap_region_iterate(&cl); 5465 guarantee(!cl.failures(), "bitmap verification"); 5466 } 5467 5468 class G1CheckCSetFastTableClosure : public HeapRegionClosure { 5469 private: 5470 bool _failures; 5471 public: 5472 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { } 5473 5474 virtual bool doHeapRegion(HeapRegion* hr) { 5475 uint i = hr->hrm_index(); 5476 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i); 5477 if (hr->is_humongous()) { 5478 if (hr->in_collection_set()) { 5479 gclog_or_tty->print_cr("\n## humongous region %u in CSet", i); 5480 _failures = true; 5481 return true; 5482 } 5483 if (cset_state.is_in_cset()) { 5484 gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i); 5485 _failures = true; 5486 return true; 5487 } 5488 if (hr->is_continues_humongous() && cset_state.is_humongous()) { 5489 gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i); 5490 _failures = true; 5491 return true; 5492 } 5493 } else { 5494 if (cset_state.is_humongous()) { 5495 gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i); 5496 _failures = true; 5497 return true; 5498 } 5499 if (hr->in_collection_set() != cset_state.is_in_cset()) { 5500 gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u", 5501 hr->in_collection_set(), cset_state.value(), i); 5502 _failures = true; 5503 return true; 5504 } 5505 if (cset_state.is_in_cset()) { 5506 if (hr->is_young() != (cset_state.is_young())) { 5507 gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u", 5508 hr->is_young(), cset_state.value(), i); 5509 _failures = true; 5510 return true; 5511 } 5512 if (hr->is_old() != (cset_state.is_old())) { 5513 gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u", 5514 hr->is_old(), cset_state.value(), i); 5515 _failures = true; 5516 return true; 5517 } 5518 } 5519 } 5520 return false; 5521 } 5522 5523 bool failures() const { return _failures; } 5524 }; 5525 5526 bool G1CollectedHeap::check_cset_fast_test() { 5527 G1CheckCSetFastTableClosure cl; 5528 _hrm.iterate(&cl); 5529 return !cl.failures(); 5530 } 5531 #endif // PRODUCT 5532 5533 void G1CollectedHeap::cleanUpCardTable() { 5534 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5535 double start = os::elapsedTime(); 5536 5537 { 5538 // Iterate over the dirty cards region list. 5539 G1ParCleanupCTTask cleanup_task(ct_bs, this); 5540 5541 workers()->run_task(&cleanup_task); 5542 #ifndef PRODUCT 5543 if (G1VerifyCTCleanup || VerifyAfterGC) { 5544 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs); 5545 heap_region_iterate(&cleanup_verifier); 5546 } 5547 #endif 5548 } 5549 5550 double elapsed = os::elapsedTime() - start; 5551 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0); 5552 } 5553 5554 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) { 5555 size_t pre_used = 0; 5556 FreeRegionList local_free_list("Local List for CSet Freeing"); 5557 5558 double young_time_ms = 0.0; 5559 double non_young_time_ms = 0.0; 5560 5561 // Since the collection set is a superset of the the young list, 5562 // all we need to do to clear the young list is clear its 5563 // head and length, and unlink any young regions in the code below 5564 _young_list->clear(); 5565 5566 G1CollectorPolicy* policy = g1_policy(); 5567 5568 double start_sec = os::elapsedTime(); 5569 bool non_young = true; 5570 5571 HeapRegion* cur = cs_head; 5572 int age_bound = -1; 5573 size_t rs_lengths = 0; 5574 5575 while (cur != NULL) { 5576 assert(!is_on_master_free_list(cur), "sanity"); 5577 if (non_young) { 5578 if (cur->is_young()) { 5579 double end_sec = os::elapsedTime(); 5580 double elapsed_ms = (end_sec - start_sec) * 1000.0; 5581 non_young_time_ms += elapsed_ms; 5582 5583 start_sec = os::elapsedTime(); 5584 non_young = false; 5585 } 5586 } else { 5587 if (!cur->is_young()) { 5588 double end_sec = os::elapsedTime(); 5589 double elapsed_ms = (end_sec - start_sec) * 1000.0; 5590 young_time_ms += elapsed_ms; 5591 5592 start_sec = os::elapsedTime(); 5593 non_young = true; 5594 } 5595 } 5596 5597 rs_lengths += cur->rem_set()->occupied_locked(); 5598 5599 HeapRegion* next = cur->next_in_collection_set(); 5600 assert(cur->in_collection_set(), "bad CS"); 5601 cur->set_next_in_collection_set(NULL); 5602 clear_in_cset(cur); 5603 5604 if (cur->is_young()) { 5605 int index = cur->young_index_in_cset(); 5606 assert(index != -1, "invariant"); 5607 assert((uint) index < policy->young_cset_region_length(), "invariant"); 5608 size_t words_survived = surviving_young_words[index]; 5609 cur->record_surv_words_in_group(words_survived); 5610 5611 // At this point the we have 'popped' cur from the collection set 5612 // (linked via next_in_collection_set()) but it is still in the 5613 // young list (linked via next_young_region()). Clear the 5614 // _next_young_region field. 5615 cur->set_next_young_region(NULL); 5616 } else { 5617 int index = cur->young_index_in_cset(); 5618 assert(index == -1, "invariant"); 5619 } 5620 5621 assert( (cur->is_young() && cur->young_index_in_cset() > -1) || 5622 (!cur->is_young() && cur->young_index_in_cset() == -1), 5623 "invariant" ); 5624 5625 if (!cur->evacuation_failed()) { 5626 MemRegion used_mr = cur->used_region(); 5627 5628 // And the region is empty. 5629 assert(!used_mr.is_empty(), "Should not have empty regions in a CS."); 5630 pre_used += cur->used(); 5631 free_region(cur, &local_free_list, false /* par */, true /* locked */); 5632 } else { 5633 cur->uninstall_surv_rate_group(); 5634 if (cur->is_young()) { 5635 cur->set_young_index_in_cset(-1); 5636 } 5637 cur->set_evacuation_failed(false); 5638 // The region is now considered to be old. 5639 cur->set_old(); 5640 // Do some allocation statistics accounting. Regions that failed evacuation 5641 // are always made old, so there is no need to update anything in the young 5642 // gen statistics, but we need to update old gen statistics. 5643 size_t used_words = cur->marked_bytes() / HeapWordSize; 5644 _old_evac_stats.add_failure_used_and_waste(used_words, HeapRegion::GrainWords - used_words); 5645 _old_set.add(cur); 5646 evacuation_info.increment_collectionset_used_after(cur->used()); 5647 } 5648 cur = next; 5649 } 5650 5651 evacuation_info.set_regions_freed(local_free_list.length()); 5652 policy->record_max_rs_lengths(rs_lengths); 5653 policy->cset_regions_freed(); 5654 5655 double end_sec = os::elapsedTime(); 5656 double elapsed_ms = (end_sec - start_sec) * 1000.0; 5657 5658 if (non_young) { 5659 non_young_time_ms += elapsed_ms; 5660 } else { 5661 young_time_ms += elapsed_ms; 5662 } 5663 5664 prepend_to_freelist(&local_free_list); 5665 decrement_summary_bytes(pre_used); 5666 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms); 5667 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms); 5668 } 5669 5670 class G1FreeHumongousRegionClosure : public HeapRegionClosure { 5671 private: 5672 FreeRegionList* _free_region_list; 5673 HeapRegionSet* _proxy_set; 5674 HeapRegionSetCount _humongous_regions_removed; 5675 size_t _freed_bytes; 5676 public: 5677 5678 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) : 5679 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) { 5680 } 5681 5682 virtual bool doHeapRegion(HeapRegion* r) { 5683 if (!r->is_starts_humongous()) { 5684 return false; 5685 } 5686 5687 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 5688 5689 oop obj = (oop)r->bottom(); 5690 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap(); 5691 5692 // The following checks whether the humongous object is live are sufficient. 5693 // The main additional check (in addition to having a reference from the roots 5694 // or the young gen) is whether the humongous object has a remembered set entry. 5695 // 5696 // A humongous object cannot be live if there is no remembered set for it 5697 // because: 5698 // - there can be no references from within humongous starts regions referencing 5699 // the object because we never allocate other objects into them. 5700 // (I.e. there are no intra-region references that may be missed by the 5701 // remembered set) 5702 // - as soon there is a remembered set entry to the humongous starts region 5703 // (i.e. it has "escaped" to an old object) this remembered set entry will stay 5704 // until the end of a concurrent mark. 5705 // 5706 // It is not required to check whether the object has been found dead by marking 5707 // or not, in fact it would prevent reclamation within a concurrent cycle, as 5708 // all objects allocated during that time are considered live. 5709 // SATB marking is even more conservative than the remembered set. 5710 // So if at this point in the collection there is no remembered set entry, 5711 // nobody has a reference to it. 5712 // At the start of collection we flush all refinement logs, and remembered sets 5713 // are completely up-to-date wrt to references to the humongous object. 5714 // 5715 // Other implementation considerations: 5716 // - never consider object arrays at this time because they would pose 5717 // considerable effort for cleaning up the the remembered sets. This is 5718 // required because stale remembered sets might reference locations that 5719 // are currently allocated into. 5720 uint region_idx = r->hrm_index(); 5721 if (!g1h->is_humongous_reclaim_candidate(region_idx) || 5722 !r->rem_set()->is_empty()) { 5723 5724 if (G1TraceEagerReclaimHumongousObjects) { 5725 gclog_or_tty->print_cr("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", 5726 region_idx, 5727 (size_t)obj->size() * HeapWordSize, 5728 p2i(r->bottom()), 5729 r->rem_set()->occupied(), 5730 r->rem_set()->strong_code_roots_list_length(), 5731 next_bitmap->isMarked(r->bottom()), 5732 g1h->is_humongous_reclaim_candidate(region_idx), 5733 obj->is_typeArray() 5734 ); 5735 } 5736 5737 return false; 5738 } 5739 5740 guarantee(obj->is_typeArray(), 5741 "Only eagerly reclaiming type arrays is supported, but the object " 5742 PTR_FORMAT " is not.", p2i(r->bottom())); 5743 5744 if (G1TraceEagerReclaimHumongousObjects) { 5745 gclog_or_tty->print_cr("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", 5746 region_idx, 5747 (size_t)obj->size() * HeapWordSize, 5748 p2i(r->bottom()), 5749 r->rem_set()->occupied(), 5750 r->rem_set()->strong_code_roots_list_length(), 5751 next_bitmap->isMarked(r->bottom()), 5752 g1h->is_humongous_reclaim_candidate(region_idx), 5753 obj->is_typeArray() 5754 ); 5755 } 5756 // Need to clear mark bit of the humongous object if already set. 5757 if (next_bitmap->isMarked(r->bottom())) { 5758 next_bitmap->clear(r->bottom()); 5759 } 5760 do { 5761 HeapRegion* next = g1h->next_region_in_humongous(r); 5762 _freed_bytes += r->used(); 5763 r->set_containing_set(NULL); 5764 _humongous_regions_removed.increment(1u, r->capacity()); 5765 g1h->free_humongous_region(r, _free_region_list, false); 5766 r = next; 5767 } while (r != NULL); 5768 5769 return false; 5770 } 5771 5772 HeapRegionSetCount& humongous_free_count() { 5773 return _humongous_regions_removed; 5774 } 5775 5776 size_t bytes_freed() const { 5777 return _freed_bytes; 5778 } 5779 5780 size_t humongous_reclaimed() const { 5781 return _humongous_regions_removed.length(); 5782 } 5783 }; 5784 5785 void G1CollectedHeap::eagerly_reclaim_humongous_regions() { 5786 assert_at_safepoint(true); 5787 5788 if (!G1EagerReclaimHumongousObjects || 5789 (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) { 5790 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0); 5791 return; 5792 } 5793 5794 double start_time = os::elapsedTime(); 5795 5796 FreeRegionList local_cleanup_list("Local Humongous Cleanup List"); 5797 5798 G1FreeHumongousRegionClosure cl(&local_cleanup_list); 5799 heap_region_iterate(&cl); 5800 5801 HeapRegionSetCount empty_set; 5802 remove_from_old_sets(empty_set, cl.humongous_free_count()); 5803 5804 G1HRPrinter* hrp = hr_printer(); 5805 if (hrp->is_active()) { 5806 FreeRegionListIterator iter(&local_cleanup_list); 5807 while (iter.more_available()) { 5808 HeapRegion* hr = iter.get_next(); 5809 hrp->cleanup(hr); 5810 } 5811 } 5812 5813 prepend_to_freelist(&local_cleanup_list); 5814 decrement_summary_bytes(cl.bytes_freed()); 5815 5816 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0, 5817 cl.humongous_reclaimed()); 5818 } 5819 5820 // This routine is similar to the above but does not record 5821 // any policy statistics or update free lists; we are abandoning 5822 // the current incremental collection set in preparation of a 5823 // full collection. After the full GC we will start to build up 5824 // the incremental collection set again. 5825 // This is only called when we're doing a full collection 5826 // and is immediately followed by the tearing down of the young list. 5827 5828 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) { 5829 HeapRegion* cur = cs_head; 5830 5831 while (cur != NULL) { 5832 HeapRegion* next = cur->next_in_collection_set(); 5833 assert(cur->in_collection_set(), "bad CS"); 5834 cur->set_next_in_collection_set(NULL); 5835 clear_in_cset(cur); 5836 cur->set_young_index_in_cset(-1); 5837 cur = next; 5838 } 5839 } 5840 5841 void G1CollectedHeap::set_free_regions_coming() { 5842 if (G1ConcRegionFreeingVerbose) { 5843 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " 5844 "setting free regions coming"); 5845 } 5846 5847 assert(!free_regions_coming(), "pre-condition"); 5848 _free_regions_coming = true; 5849 } 5850 5851 void G1CollectedHeap::reset_free_regions_coming() { 5852 assert(free_regions_coming(), "pre-condition"); 5853 5854 { 5855 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 5856 _free_regions_coming = false; 5857 SecondaryFreeList_lock->notify_all(); 5858 } 5859 5860 if (G1ConcRegionFreeingVerbose) { 5861 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " 5862 "reset free regions coming"); 5863 } 5864 } 5865 5866 void G1CollectedHeap::wait_while_free_regions_coming() { 5867 // Most of the time we won't have to wait, so let's do a quick test 5868 // first before we take the lock. 5869 if (!free_regions_coming()) { 5870 return; 5871 } 5872 5873 if (G1ConcRegionFreeingVerbose) { 5874 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " 5875 "waiting for free regions"); 5876 } 5877 5878 { 5879 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 5880 while (free_regions_coming()) { 5881 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 5882 } 5883 } 5884 5885 if (G1ConcRegionFreeingVerbose) { 5886 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " 5887 "done waiting for free regions"); 5888 } 5889 } 5890 5891 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) { 5892 return _allocator->is_retained_old_region(hr); 5893 } 5894 5895 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 5896 _young_list->push_region(hr); 5897 } 5898 5899 class NoYoungRegionsClosure: public HeapRegionClosure { 5900 private: 5901 bool _success; 5902 public: 5903 NoYoungRegionsClosure() : _success(true) { } 5904 bool doHeapRegion(HeapRegion* r) { 5905 if (r->is_young()) { 5906 gclog_or_tty->print_cr("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young", 5907 p2i(r->bottom()), p2i(r->end())); 5908 _success = false; 5909 } 5910 return false; 5911 } 5912 bool success() { return _success; } 5913 }; 5914 5915 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) { 5916 bool ret = _young_list->check_list_empty(check_sample); 5917 5918 if (check_heap) { 5919 NoYoungRegionsClosure closure; 5920 heap_region_iterate(&closure); 5921 ret = ret && closure.success(); 5922 } 5923 5924 return ret; 5925 } 5926 5927 class TearDownRegionSetsClosure : public HeapRegionClosure { 5928 private: 5929 HeapRegionSet *_old_set; 5930 5931 public: 5932 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { } 5933 5934 bool doHeapRegion(HeapRegion* r) { 5935 if (r->is_old()) { 5936 _old_set->remove(r); 5937 } else { 5938 // We ignore free regions, we'll empty the free list afterwards. 5939 // We ignore young regions, we'll empty the young list afterwards. 5940 // We ignore humongous regions, we're not tearing down the 5941 // humongous regions set. 5942 assert(r->is_free() || r->is_young() || r->is_humongous(), 5943 "it cannot be another type"); 5944 } 5945 return false; 5946 } 5947 5948 ~TearDownRegionSetsClosure() { 5949 assert(_old_set->is_empty(), "post-condition"); 5950 } 5951 }; 5952 5953 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) { 5954 assert_at_safepoint(true /* should_be_vm_thread */); 5955 5956 if (!free_list_only) { 5957 TearDownRegionSetsClosure cl(&_old_set); 5958 heap_region_iterate(&cl); 5959 5960 // Note that emptying the _young_list is postponed and instead done as 5961 // the first step when rebuilding the regions sets again. The reason for 5962 // this is that during a full GC string deduplication needs to know if 5963 // a collected region was young or old when the full GC was initiated. 5964 } 5965 _hrm.remove_all_free_regions(); 5966 } 5967 5968 void G1CollectedHeap::increase_used(size_t bytes) { 5969 _summary_bytes_used += bytes; 5970 } 5971 5972 void G1CollectedHeap::decrease_used(size_t bytes) { 5973 assert(_summary_bytes_used >= bytes, 5974 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT, 5975 _summary_bytes_used, bytes); 5976 _summary_bytes_used -= bytes; 5977 } 5978 5979 void G1CollectedHeap::set_used(size_t bytes) { 5980 _summary_bytes_used = bytes; 5981 } 5982 5983 class RebuildRegionSetsClosure : public HeapRegionClosure { 5984 private: 5985 bool _free_list_only; 5986 HeapRegionSet* _old_set; 5987 HeapRegionManager* _hrm; 5988 size_t _total_used; 5989 5990 public: 5991 RebuildRegionSetsClosure(bool free_list_only, 5992 HeapRegionSet* old_set, HeapRegionManager* hrm) : 5993 _free_list_only(free_list_only), 5994 _old_set(old_set), _hrm(hrm), _total_used(0) { 5995 assert(_hrm->num_free_regions() == 0, "pre-condition"); 5996 if (!free_list_only) { 5997 assert(_old_set->is_empty(), "pre-condition"); 5998 } 5999 } 6000 6001 bool doHeapRegion(HeapRegion* r) { 6002 if (r->is_empty()) { 6003 // Add free regions to the free list 6004 r->set_free(); 6005 r->set_allocation_context(AllocationContext::system()); 6006 _hrm->insert_into_free_list(r); 6007 } else if (!_free_list_only) { 6008 assert(!r->is_young(), "we should not come across young regions"); 6009 6010 if (r->is_humongous()) { 6011 // We ignore humongous regions. We left the humongous set unchanged. 6012 } else { 6013 // Objects that were compacted would have ended up on regions 6014 // that were previously old or free. Archive regions (which are 6015 // old) will not have been touched. 6016 assert(r->is_free() || r->is_old(), "invariant"); 6017 // We now consider them old, so register as such. Leave 6018 // archive regions set that way, however, while still adding 6019 // them to the old set. 6020 if (!r->is_archive()) { 6021 r->set_old(); 6022 } 6023 _old_set->add(r); 6024 } 6025 _total_used += r->used(); 6026 } 6027 6028 return false; 6029 } 6030 6031 size_t total_used() { 6032 return _total_used; 6033 } 6034 }; 6035 6036 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { 6037 assert_at_safepoint(true /* should_be_vm_thread */); 6038 6039 if (!free_list_only) { 6040 _young_list->empty_list(); 6041 } 6042 6043 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm); 6044 heap_region_iterate(&cl); 6045 6046 if (!free_list_only) { 6047 set_used(cl.total_used()); 6048 if (_archive_allocator != NULL) { 6049 _archive_allocator->clear_used(); 6050 } 6051 } 6052 assert(used_unlocked() == recalculate_used(), 6053 "inconsistent used_unlocked(), " 6054 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT, 6055 used_unlocked(), recalculate_used()); 6056 } 6057 6058 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) { 6059 _refine_cte_cl->set_concurrent(concurrent); 6060 } 6061 6062 bool G1CollectedHeap::is_in_closed_subset(const void* p) const { 6063 HeapRegion* hr = heap_region_containing(p); 6064 return hr->is_in(p); 6065 } 6066 6067 // Methods for the mutator alloc region 6068 6069 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 6070 bool force) { 6071 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6072 assert(!force || g1_policy()->can_expand_young_list(), 6073 "if force is true we should be able to expand the young list"); 6074 bool young_list_full = g1_policy()->is_young_list_full(); 6075 if (force || !young_list_full) { 6076 HeapRegion* new_alloc_region = new_region(word_size, 6077 false /* is_old */, 6078 false /* do_expand */); 6079 if (new_alloc_region != NULL) { 6080 set_region_short_lived_locked(new_alloc_region); 6081 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full); 6082 check_bitmaps("Mutator Region Allocation", new_alloc_region); 6083 return new_alloc_region; 6084 } 6085 } 6086 return NULL; 6087 } 6088 6089 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 6090 size_t allocated_bytes) { 6091 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6092 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden"); 6093 6094 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region); 6095 increase_used(allocated_bytes); 6096 _hr_printer.retire(alloc_region); 6097 // We update the eden sizes here, when the region is retired, 6098 // instead of when it's allocated, since this is the point that its 6099 // used space has been recored in _summary_bytes_used. 6100 g1mm()->update_eden_size(); 6101 } 6102 6103 // Methods for the GC alloc regions 6104 6105 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, 6106 uint count, 6107 InCSetState dest) { 6108 assert(FreeList_lock->owned_by_self(), "pre-condition"); 6109 6110 if (count < g1_policy()->max_regions(dest)) { 6111 const bool is_survivor = (dest.is_young()); 6112 HeapRegion* new_alloc_region = new_region(word_size, 6113 !is_survivor, 6114 true /* do_expand */); 6115 if (new_alloc_region != NULL) { 6116 // We really only need to do this for old regions given that we 6117 // should never scan survivors. But it doesn't hurt to do it 6118 // for survivors too. 6119 new_alloc_region->record_timestamp(); 6120 if (is_survivor) { 6121 new_alloc_region->set_survivor(); 6122 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor); 6123 check_bitmaps("Survivor Region Allocation", new_alloc_region); 6124 } else { 6125 new_alloc_region->set_old(); 6126 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old); 6127 check_bitmaps("Old Region Allocation", new_alloc_region); 6128 } 6129 bool during_im = collector_state()->during_initial_mark_pause(); 6130 new_alloc_region->note_start_of_copying(during_im); 6131 return new_alloc_region; 6132 } 6133 } 6134 return NULL; 6135 } 6136 6137 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 6138 size_t allocated_bytes, 6139 InCSetState dest) { 6140 bool during_im = collector_state()->during_initial_mark_pause(); 6141 alloc_region->note_end_of_copying(during_im); 6142 g1_policy()->record_bytes_copied_during_gc(allocated_bytes); 6143 if (dest.is_young()) { 6144 young_list()->add_survivor_region(alloc_region); 6145 } else { 6146 _old_set.add(alloc_region); 6147 } 6148 _hr_printer.retire(alloc_region); 6149 } 6150 6151 HeapRegion* G1CollectedHeap::alloc_highest_free_region() { 6152 bool expanded = false; 6153 uint index = _hrm.find_highest_free(&expanded); 6154 6155 if (index != G1_NO_HRM_INDEX) { 6156 if (expanded) { 6157 ergo_verbose1(ErgoHeapSizing, 6158 "attempt heap expansion", 6159 ergo_format_reason("requested address range outside heap bounds") 6160 ergo_format_byte("region size"), 6161 HeapRegion::GrainWords * HeapWordSize); 6162 } 6163 _hrm.allocate_free_regions_starting_at(index, 1); 6164 return region_at(index); 6165 } 6166 return NULL; 6167 } 6168 6169 // Heap region set verification 6170 6171 class VerifyRegionListsClosure : public HeapRegionClosure { 6172 private: 6173 HeapRegionSet* _old_set; 6174 HeapRegionSet* _humongous_set; 6175 HeapRegionManager* _hrm; 6176 6177 public: 6178 HeapRegionSetCount _old_count; 6179 HeapRegionSetCount _humongous_count; 6180 HeapRegionSetCount _free_count; 6181 6182 VerifyRegionListsClosure(HeapRegionSet* old_set, 6183 HeapRegionSet* humongous_set, 6184 HeapRegionManager* hrm) : 6185 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm), 6186 _old_count(), _humongous_count(), _free_count(){ } 6187 6188 bool doHeapRegion(HeapRegion* hr) { 6189 if (hr->is_young()) { 6190 // TODO 6191 } else if (hr->is_humongous()) { 6192 assert(hr->containing_set() == _humongous_set, "Heap region %u is humongous but not in humongous set.", hr->hrm_index()); 6193 _humongous_count.increment(1u, hr->capacity()); 6194 } else if (hr->is_empty()) { 6195 assert(_hrm->is_free(hr), "Heap region %u is empty but not on the free list.", hr->hrm_index()); 6196 _free_count.increment(1u, hr->capacity()); 6197 } else if (hr->is_old()) { 6198 assert(hr->containing_set() == _old_set, "Heap region %u is old but not in the old set.", hr->hrm_index()); 6199 _old_count.increment(1u, hr->capacity()); 6200 } else { 6201 // There are no other valid region types. Check for one invalid 6202 // one we can identify: pinned without old or humongous set. 6203 assert(!hr->is_pinned(), "Heap region %u is pinned but not old (archive) or humongous.", hr->hrm_index()); 6204 ShouldNotReachHere(); 6205 } 6206 return false; 6207 } 6208 6209 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) { 6210 guarantee(old_set->length() == _old_count.length(), "Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()); 6211 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), "Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6212 old_set->total_capacity_bytes(), _old_count.capacity()); 6213 6214 guarantee(humongous_set->length() == _humongous_count.length(), "Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()); 6215 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), "Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6216 humongous_set->total_capacity_bytes(), _humongous_count.capacity()); 6217 6218 guarantee(free_list->num_free_regions() == _free_count.length(), "Free list count mismatch. Expected %u, actual %u.", free_list->num_free_regions(), _free_count.length()); 6219 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), "Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6220 free_list->total_capacity_bytes(), _free_count.capacity()); 6221 } 6222 }; 6223 6224 void G1CollectedHeap::verify_region_sets() { 6225 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6226 6227 // First, check the explicit lists. 6228 _hrm.verify(); 6229 { 6230 // Given that a concurrent operation might be adding regions to 6231 // the secondary free list we have to take the lock before 6232 // verifying it. 6233 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6234 _secondary_free_list.verify_list(); 6235 } 6236 6237 // If a concurrent region freeing operation is in progress it will 6238 // be difficult to correctly attributed any free regions we come 6239 // across to the correct free list given that they might belong to 6240 // one of several (free_list, secondary_free_list, any local lists, 6241 // etc.). So, if that's the case we will skip the rest of the 6242 // verification operation. Alternatively, waiting for the concurrent 6243 // operation to complete will have a non-trivial effect on the GC's 6244 // operation (no concurrent operation will last longer than the 6245 // interval between two calls to verification) and it might hide 6246 // any issues that we would like to catch during testing. 6247 if (free_regions_coming()) { 6248 return; 6249 } 6250 6251 // Make sure we append the secondary_free_list on the free_list so 6252 // that all free regions we will come across can be safely 6253 // attributed to the free_list. 6254 append_secondary_free_list_if_not_empty_with_lock(); 6255 6256 // Finally, make sure that the region accounting in the lists is 6257 // consistent with what we see in the heap. 6258 6259 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm); 6260 heap_region_iterate(&cl); 6261 cl.verify_counts(&_old_set, &_humongous_set, &_hrm); 6262 } 6263 6264 // Optimized nmethod scanning 6265 6266 class RegisterNMethodOopClosure: public OopClosure { 6267 G1CollectedHeap* _g1h; 6268 nmethod* _nm; 6269 6270 template <class T> void do_oop_work(T* p) { 6271 T heap_oop = oopDesc::load_heap_oop(p); 6272 if (!oopDesc::is_null(heap_oop)) { 6273 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 6274 HeapRegion* hr = _g1h->heap_region_containing(obj); 6275 assert(!hr->is_continues_humongous(), 6276 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 6277 " starting at " HR_FORMAT, 6278 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 6279 6280 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries. 6281 hr->add_strong_code_root_locked(_nm); 6282 } 6283 } 6284 6285 public: 6286 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 6287 _g1h(g1h), _nm(nm) {} 6288 6289 void do_oop(oop* p) { do_oop_work(p); } 6290 void do_oop(narrowOop* p) { do_oop_work(p); } 6291 }; 6292 6293 class UnregisterNMethodOopClosure: public OopClosure { 6294 G1CollectedHeap* _g1h; 6295 nmethod* _nm; 6296 6297 template <class T> void do_oop_work(T* p) { 6298 T heap_oop = oopDesc::load_heap_oop(p); 6299 if (!oopDesc::is_null(heap_oop)) { 6300 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 6301 HeapRegion* hr = _g1h->heap_region_containing(obj); 6302 assert(!hr->is_continues_humongous(), 6303 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 6304 " starting at " HR_FORMAT, 6305 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 6306 6307 hr->remove_strong_code_root(_nm); 6308 } 6309 } 6310 6311 public: 6312 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 6313 _g1h(g1h), _nm(nm) {} 6314 6315 void do_oop(oop* p) { do_oop_work(p); } 6316 void do_oop(narrowOop* p) { do_oop_work(p); } 6317 }; 6318 6319 void G1CollectedHeap::register_nmethod(nmethod* nm) { 6320 CollectedHeap::register_nmethod(nm); 6321 6322 guarantee(nm != NULL, "sanity"); 6323 RegisterNMethodOopClosure reg_cl(this, nm); 6324 nm->oops_do(®_cl); 6325 } 6326 6327 void G1CollectedHeap::unregister_nmethod(nmethod* nm) { 6328 CollectedHeap::unregister_nmethod(nm); 6329 6330 guarantee(nm != NULL, "sanity"); 6331 UnregisterNMethodOopClosure reg_cl(this, nm); 6332 nm->oops_do(®_cl, true); 6333 } 6334 6335 void G1CollectedHeap::purge_code_root_memory() { 6336 double purge_start = os::elapsedTime(); 6337 G1CodeRootSet::purge(); 6338 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0; 6339 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms); 6340 } 6341 6342 class RebuildStrongCodeRootClosure: public CodeBlobClosure { 6343 G1CollectedHeap* _g1h; 6344 6345 public: 6346 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) : 6347 _g1h(g1h) {} 6348 6349 void do_code_blob(CodeBlob* cb) { 6350 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL; 6351 if (nm == NULL) { 6352 return; 6353 } 6354 6355 if (ScavengeRootsInCode) { 6356 _g1h->register_nmethod(nm); 6357 } 6358 } 6359 }; 6360 6361 void G1CollectedHeap::rebuild_strong_code_roots() { 6362 RebuildStrongCodeRootClosure blob_cl(this); 6363 CodeCache::blobs_do(&blob_cl); 6364 }