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 if ((first + 1) == last) { 370 // the series has a single humongous region 371 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, obj_top); 372 } else { 373 // the series has more than one humongous regions 374 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, first_hr->end()); 375 } 376 } 377 378 // Now, we will update the top fields of the "continues humongous" 379 // regions. The reason we need to do this is that, otherwise, 380 // these regions would look empty and this will confuse parts of 381 // G1. For example, the code that looks for a consecutive number 382 // of empty regions will consider them empty and try to 383 // re-allocate them. We can extend is_empty() to also include 384 // !is_continues_humongous(), but it is easier to just update the top 385 // fields here. The way we set top for all regions (i.e., top == 386 // end for all regions but the last one, top == new_top for the 387 // last one) is actually used when we will free up the humongous 388 // region in free_humongous_region(). 389 hr = NULL; 390 for (uint i = first + 1; i < last; ++i) { 391 hr = region_at(i); 392 if ((i + 1) == last) { 393 // last continues humongous region 394 assert(hr->bottom() < obj_top && obj_top <= hr->end(), 395 "new_top should fall on this region"); 396 hr->set_top(obj_top); 397 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, obj_top); 398 } else { 399 // not last one 400 assert(obj_top > hr->end(), "obj_top should be above this region"); 401 hr->set_top(hr->end()); 402 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end()); 403 } 404 } 405 // If we have continues humongous regions (hr != NULL), its top should 406 // match obj_top. 407 assert(hr == NULL || (hr->top() == obj_top), "sanity"); 408 check_bitmaps("Humongous Region Allocation", first_hr); 409 410 increase_used(word_size * HeapWordSize); 411 412 for (uint i = first; i < last; ++i) { 413 _humongous_set.add(region_at(i)); 414 } 415 416 return new_obj; 417 } 418 419 // If could fit into free regions w/o expansion, try. 420 // Otherwise, if can expand, do so. 421 // Otherwise, if using ex regions might help, try with ex given back. 422 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) { 423 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 424 425 verify_region_sets_optional(); 426 427 uint first = G1_NO_HRM_INDEX; 428 uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords); 429 430 if (obj_regions == 1) { 431 // Only one region to allocate, try to use a fast path by directly allocating 432 // from the free lists. Do not try to expand here, we will potentially do that 433 // later. 434 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */); 435 if (hr != NULL) { 436 first = hr->hrm_index(); 437 } 438 } else { 439 // We can't allocate humongous regions spanning more than one region while 440 // cleanupComplete() is running, since some of the regions we find to be 441 // empty might not yet be added to the free list. It is not straightforward 442 // to know in which list they are on so that we can remove them. We only 443 // need to do this if we need to allocate more than one region to satisfy the 444 // current humongous allocation request. If we are only allocating one region 445 // we use the one-region region allocation code (see above), that already 446 // potentially waits for regions from the secondary free list. 447 wait_while_free_regions_coming(); 448 append_secondary_free_list_if_not_empty_with_lock(); 449 450 // Policy: Try only empty regions (i.e. already committed first). Maybe we 451 // are lucky enough to find some. 452 first = _hrm.find_contiguous_only_empty(obj_regions); 453 if (first != G1_NO_HRM_INDEX) { 454 _hrm.allocate_free_regions_starting_at(first, obj_regions); 455 } 456 } 457 458 if (first == G1_NO_HRM_INDEX) { 459 // Policy: We could not find enough regions for the humongous object in the 460 // free list. Look through the heap to find a mix of free and uncommitted regions. 461 // If so, try expansion. 462 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions); 463 if (first != G1_NO_HRM_INDEX) { 464 // We found something. Make sure these regions are committed, i.e. expand 465 // the heap. Alternatively we could do a defragmentation GC. 466 ergo_verbose1(ErgoHeapSizing, 467 "attempt heap expansion", 468 ergo_format_reason("humongous allocation request failed") 469 ergo_format_byte("allocation request"), 470 word_size * HeapWordSize); 471 472 _hrm.expand_at(first, obj_regions); 473 g1_policy()->record_new_heap_size(num_regions()); 474 475 #ifdef ASSERT 476 for (uint i = first; i < first + obj_regions; ++i) { 477 HeapRegion* hr = region_at(i); 478 assert(hr->is_free(), "sanity"); 479 assert(hr->is_empty(), "sanity"); 480 assert(is_on_master_free_list(hr), "sanity"); 481 } 482 #endif 483 _hrm.allocate_free_regions_starting_at(first, obj_regions); 484 } else { 485 // Policy: Potentially trigger a defragmentation GC. 486 } 487 } 488 489 HeapWord* result = NULL; 490 if (first != G1_NO_HRM_INDEX) { 491 result = humongous_obj_allocate_initialize_regions(first, obj_regions, 492 word_size, context); 493 assert(result != NULL, "it should always return a valid result"); 494 495 // A successful humongous object allocation changes the used space 496 // information of the old generation so we need to recalculate the 497 // sizes and update the jstat counters here. 498 g1mm()->update_sizes(); 499 } 500 501 verify_region_sets_optional(); 502 503 return result; 504 } 505 506 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) { 507 assert_heap_not_locked_and_not_at_safepoint(); 508 assert(!is_humongous(word_size), "we do not allow humongous TLABs"); 509 510 uint dummy_gc_count_before; 511 uint dummy_gclocker_retry_count = 0; 512 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count); 513 } 514 515 HeapWord* 516 G1CollectedHeap::mem_allocate(size_t word_size, 517 bool* gc_overhead_limit_was_exceeded) { 518 assert_heap_not_locked_and_not_at_safepoint(); 519 520 // Loop until the allocation is satisfied, or unsatisfied after GC. 521 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 522 uint gc_count_before; 523 524 HeapWord* result = NULL; 525 if (!is_humongous(word_size)) { 526 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count); 527 } else { 528 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count); 529 } 530 if (result != NULL) { 531 return result; 532 } 533 534 // Create the garbage collection operation... 535 VM_G1CollectForAllocation op(gc_count_before, word_size); 536 op.set_allocation_context(AllocationContext::current()); 537 538 // ...and get the VM thread to execute it. 539 VMThread::execute(&op); 540 541 if (op.prologue_succeeded() && op.pause_succeeded()) { 542 // If the operation was successful we'll return the result even 543 // if it is NULL. If the allocation attempt failed immediately 544 // after a Full GC, it's unlikely we'll be able to allocate now. 545 HeapWord* result = op.result(); 546 if (result != NULL && !is_humongous(word_size)) { 547 // Allocations that take place on VM operations do not do any 548 // card dirtying and we have to do it here. We only have to do 549 // this for non-humongous allocations, though. 550 dirty_young_block(result, word_size); 551 } 552 return result; 553 } else { 554 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 555 return NULL; 556 } 557 assert(op.result() == NULL, 558 "the result should be NULL if the VM op did not succeed"); 559 } 560 561 // Give a warning if we seem to be looping forever. 562 if ((QueuedAllocationWarningCount > 0) && 563 (try_count % QueuedAllocationWarningCount == 0)) { 564 warning("G1CollectedHeap::mem_allocate retries %d times", try_count); 565 } 566 } 567 568 ShouldNotReachHere(); 569 return NULL; 570 } 571 572 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size, 573 AllocationContext_t context, 574 uint* gc_count_before_ret, 575 uint* gclocker_retry_count_ret) { 576 // Make sure you read the note in attempt_allocation_humongous(). 577 578 assert_heap_not_locked_and_not_at_safepoint(); 579 assert(!is_humongous(word_size), "attempt_allocation_slow() should not " 580 "be called for humongous allocation requests"); 581 582 // We should only get here after the first-level allocation attempt 583 // (attempt_allocation()) failed to allocate. 584 585 // We will loop until a) we manage to successfully perform the 586 // allocation or b) we successfully schedule a collection which 587 // fails to perform the allocation. b) is the only case when we'll 588 // return NULL. 589 HeapWord* result = NULL; 590 for (int try_count = 1; /* we'll return */; try_count += 1) { 591 bool should_try_gc; 592 uint gc_count_before; 593 594 { 595 MutexLockerEx x(Heap_lock); 596 result = _allocator->attempt_allocation_locked(word_size, context); 597 if (result != NULL) { 598 return result; 599 } 600 601 if (GC_locker::is_active_and_needs_gc()) { 602 if (g1_policy()->can_expand_young_list()) { 603 // No need for an ergo verbose message here, 604 // can_expand_young_list() does this when it returns true. 605 result = _allocator->attempt_allocation_force(word_size, context); 606 if (result != NULL) { 607 return result; 608 } 609 } 610 should_try_gc = false; 611 } else { 612 // The GCLocker may not be active but the GCLocker initiated 613 // GC may not yet have been performed (GCLocker::needs_gc() 614 // returns true). In this case we do not try this GC and 615 // wait until the GCLocker initiated GC is performed, and 616 // then retry the allocation. 617 if (GC_locker::needs_gc()) { 618 should_try_gc = false; 619 } else { 620 // Read the GC count while still holding the Heap_lock. 621 gc_count_before = total_collections(); 622 should_try_gc = true; 623 } 624 } 625 } 626 627 if (should_try_gc) { 628 bool succeeded; 629 result = do_collection_pause(word_size, gc_count_before, &succeeded, 630 GCCause::_g1_inc_collection_pause); 631 if (result != NULL) { 632 assert(succeeded, "only way to get back a non-NULL result"); 633 return result; 634 } 635 636 if (succeeded) { 637 // If we get here we successfully scheduled a collection which 638 // failed to allocate. No point in trying to allocate 639 // further. We'll just return NULL. 640 MutexLockerEx x(Heap_lock); 641 *gc_count_before_ret = total_collections(); 642 return NULL; 643 } 644 } else { 645 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { 646 MutexLockerEx x(Heap_lock); 647 *gc_count_before_ret = total_collections(); 648 return NULL; 649 } 650 // The GCLocker is either active or the GCLocker initiated 651 // GC has not yet been performed. Stall until it is and 652 // then retry the allocation. 653 GC_locker::stall_until_clear(); 654 (*gclocker_retry_count_ret) += 1; 655 } 656 657 // We can reach here if we were unsuccessful in scheduling a 658 // collection (because another thread beat us to it) or if we were 659 // stalled due to the GC locker. In either can we should retry the 660 // allocation attempt in case another thread successfully 661 // performed a collection and reclaimed enough space. We do the 662 // first attempt (without holding the Heap_lock) here and the 663 // follow-on attempt will be at the start of the next loop 664 // iteration (after taking the Heap_lock). 665 result = _allocator->attempt_allocation(word_size, context); 666 if (result != NULL) { 667 return result; 668 } 669 670 // Give a warning if we seem to be looping forever. 671 if ((QueuedAllocationWarningCount > 0) && 672 (try_count % QueuedAllocationWarningCount == 0)) { 673 warning("G1CollectedHeap::attempt_allocation_slow() " 674 "retries %d times", try_count); 675 } 676 } 677 678 ShouldNotReachHere(); 679 return NULL; 680 } 681 682 void G1CollectedHeap::begin_archive_alloc_range() { 683 assert_at_safepoint(true /* should_be_vm_thread */); 684 if (_archive_allocator == NULL) { 685 _archive_allocator = G1ArchiveAllocator::create_allocator(this); 686 } 687 } 688 689 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) { 690 // Allocations in archive regions cannot be of a size that would be considered 691 // humongous even for a minimum-sized region, because G1 region sizes/boundaries 692 // may be different at archive-restore time. 693 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words()); 694 } 695 696 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) { 697 assert_at_safepoint(true /* should_be_vm_thread */); 698 assert(_archive_allocator != NULL, "_archive_allocator not initialized"); 699 if (is_archive_alloc_too_large(word_size)) { 700 return NULL; 701 } 702 return _archive_allocator->archive_mem_allocate(word_size); 703 } 704 705 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges, 706 size_t end_alignment_in_bytes) { 707 assert_at_safepoint(true /* should_be_vm_thread */); 708 assert(_archive_allocator != NULL, "_archive_allocator not initialized"); 709 710 // Call complete_archive to do the real work, filling in the MemRegion 711 // array with the archive regions. 712 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes); 713 delete _archive_allocator; 714 _archive_allocator = NULL; 715 } 716 717 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) { 718 assert(ranges != NULL, "MemRegion array NULL"); 719 assert(count != 0, "No MemRegions provided"); 720 MemRegion reserved = _hrm.reserved(); 721 for (size_t i = 0; i < count; i++) { 722 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) { 723 return false; 724 } 725 } 726 return true; 727 } 728 729 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) { 730 assert(!is_init_completed(), "Expect to be called at JVM init time"); 731 assert(ranges != NULL, "MemRegion array NULL"); 732 assert(count != 0, "No MemRegions provided"); 733 MutexLockerEx x(Heap_lock); 734 735 MemRegion reserved = _hrm.reserved(); 736 HeapWord* prev_last_addr = NULL; 737 HeapRegion* prev_last_region = NULL; 738 739 // Temporarily disable pretouching of heap pages. This interface is used 740 // when mmap'ing archived heap data in, so pre-touching is wasted. 741 FlagSetting fs(AlwaysPreTouch, false); 742 743 // Enable archive object checking in G1MarkSweep. We have to let it know 744 // about each archive range, so that objects in those ranges aren't marked. 745 G1MarkSweep::enable_archive_object_check(); 746 747 // For each specified MemRegion range, allocate the corresponding G1 748 // regions and mark them as archive regions. We expect the ranges in 749 // ascending starting address order, without overlap. 750 for (size_t i = 0; i < count; i++) { 751 MemRegion curr_range = ranges[i]; 752 HeapWord* start_address = curr_range.start(); 753 size_t word_size = curr_range.word_size(); 754 HeapWord* last_address = curr_range.last(); 755 size_t commits = 0; 756 757 guarantee(reserved.contains(start_address) && reserved.contains(last_address), 758 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 759 p2i(start_address), p2i(last_address)); 760 guarantee(start_address > prev_last_addr, 761 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 762 p2i(start_address), p2i(prev_last_addr)); 763 prev_last_addr = last_address; 764 765 // Check for ranges that start in the same G1 region in which the previous 766 // range ended, and adjust the start address so we don't try to allocate 767 // the same region again. If the current range is entirely within that 768 // region, skip it, just adjusting the recorded top. 769 HeapRegion* start_region = _hrm.addr_to_region(start_address); 770 if ((prev_last_region != NULL) && (start_region == prev_last_region)) { 771 start_address = start_region->end(); 772 if (start_address > last_address) { 773 increase_used(word_size * HeapWordSize); 774 start_region->set_top(last_address + 1); 775 continue; 776 } 777 start_region->set_top(start_address); 778 curr_range = MemRegion(start_address, last_address + 1); 779 start_region = _hrm.addr_to_region(start_address); 780 } 781 782 // Perform the actual region allocation, exiting if it fails. 783 // Then note how much new space we have allocated. 784 if (!_hrm.allocate_containing_regions(curr_range, &commits)) { 785 return false; 786 } 787 increase_used(word_size * HeapWordSize); 788 if (commits != 0) { 789 ergo_verbose1(ErgoHeapSizing, 790 "attempt heap expansion", 791 ergo_format_reason("allocate archive regions") 792 ergo_format_byte("total size"), 793 HeapRegion::GrainWords * HeapWordSize * commits); 794 } 795 796 // Mark each G1 region touched by the range as archive, add it to the old set, 797 // and set the allocation context and top. 798 HeapRegion* curr_region = _hrm.addr_to_region(start_address); 799 HeapRegion* last_region = _hrm.addr_to_region(last_address); 800 prev_last_region = last_region; 801 802 while (curr_region != NULL) { 803 assert(curr_region->is_empty() && !curr_region->is_pinned(), 804 "Region already in use (index %u)", curr_region->hrm_index()); 805 _hr_printer.alloc(curr_region, G1HRPrinter::Archive); 806 curr_region->set_allocation_context(AllocationContext::system()); 807 curr_region->set_archive(); 808 _old_set.add(curr_region); 809 if (curr_region != last_region) { 810 curr_region->set_top(curr_region->end()); 811 curr_region = _hrm.next_region_in_heap(curr_region); 812 } else { 813 curr_region->set_top(last_address + 1); 814 curr_region = NULL; 815 } 816 } 817 818 // Notify mark-sweep of the archive range. 819 G1MarkSweep::set_range_archive(curr_range, true); 820 } 821 return true; 822 } 823 824 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) { 825 assert(!is_init_completed(), "Expect to be called at JVM init time"); 826 assert(ranges != NULL, "MemRegion array NULL"); 827 assert(count != 0, "No MemRegions provided"); 828 MemRegion reserved = _hrm.reserved(); 829 HeapWord *prev_last_addr = NULL; 830 HeapRegion* prev_last_region = NULL; 831 832 // For each MemRegion, create filler objects, if needed, in the G1 regions 833 // that contain the address range. The address range actually within the 834 // MemRegion will not be modified. That is assumed to have been initialized 835 // elsewhere, probably via an mmap of archived heap data. 836 MutexLockerEx x(Heap_lock); 837 for (size_t i = 0; i < count; i++) { 838 HeapWord* start_address = ranges[i].start(); 839 HeapWord* last_address = ranges[i].last(); 840 841 assert(reserved.contains(start_address) && reserved.contains(last_address), 842 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 843 p2i(start_address), p2i(last_address)); 844 assert(start_address > prev_last_addr, 845 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 846 p2i(start_address), p2i(prev_last_addr)); 847 848 HeapRegion* start_region = _hrm.addr_to_region(start_address); 849 HeapRegion* last_region = _hrm.addr_to_region(last_address); 850 HeapWord* bottom_address = start_region->bottom(); 851 852 // Check for a range beginning in the same region in which the 853 // previous one ended. 854 if (start_region == prev_last_region) { 855 bottom_address = prev_last_addr + 1; 856 } 857 858 // Verify that the regions were all marked as archive regions by 859 // alloc_archive_regions. 860 HeapRegion* curr_region = start_region; 861 while (curr_region != NULL) { 862 guarantee(curr_region->is_archive(), 863 "Expected archive region at index %u", curr_region->hrm_index()); 864 if (curr_region != last_region) { 865 curr_region = _hrm.next_region_in_heap(curr_region); 866 } else { 867 curr_region = NULL; 868 } 869 } 870 871 prev_last_addr = last_address; 872 prev_last_region = last_region; 873 874 // Fill the memory below the allocated range with dummy object(s), 875 // if the region bottom does not match the range start, or if the previous 876 // range ended within the same G1 region, and there is a gap. 877 if (start_address != bottom_address) { 878 size_t fill_size = pointer_delta(start_address, bottom_address); 879 G1CollectedHeap::fill_with_objects(bottom_address, fill_size); 880 increase_used(fill_size * HeapWordSize); 881 } 882 } 883 } 884 885 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size, 886 uint* gc_count_before_ret, 887 uint* gclocker_retry_count_ret) { 888 assert_heap_not_locked_and_not_at_safepoint(); 889 assert(!is_humongous(word_size), "attempt_allocation() should not " 890 "be called for humongous allocation requests"); 891 892 AllocationContext_t context = AllocationContext::current(); 893 HeapWord* result = _allocator->attempt_allocation(word_size, context); 894 895 if (result == NULL) { 896 result = attempt_allocation_slow(word_size, 897 context, 898 gc_count_before_ret, 899 gclocker_retry_count_ret); 900 } 901 assert_heap_not_locked(); 902 if (result != NULL) { 903 dirty_young_block(result, word_size); 904 } 905 return result; 906 } 907 908 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) { 909 assert(!is_init_completed(), "Expect to be called at JVM init time"); 910 assert(ranges != NULL, "MemRegion array NULL"); 911 assert(count != 0, "No MemRegions provided"); 912 MemRegion reserved = _hrm.reserved(); 913 HeapWord* prev_last_addr = NULL; 914 HeapRegion* prev_last_region = NULL; 915 size_t size_used = 0; 916 size_t uncommitted_regions = 0; 917 918 // For each Memregion, free the G1 regions that constitute it, and 919 // notify mark-sweep that the range is no longer to be considered 'archive.' 920 MutexLockerEx x(Heap_lock); 921 for (size_t i = 0; i < count; i++) { 922 HeapWord* start_address = ranges[i].start(); 923 HeapWord* last_address = ranges[i].last(); 924 925 assert(reserved.contains(start_address) && reserved.contains(last_address), 926 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 927 p2i(start_address), p2i(last_address)); 928 assert(start_address > prev_last_addr, 929 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 930 p2i(start_address), p2i(prev_last_addr)); 931 size_used += ranges[i].byte_size(); 932 prev_last_addr = last_address; 933 934 HeapRegion* start_region = _hrm.addr_to_region(start_address); 935 HeapRegion* last_region = _hrm.addr_to_region(last_address); 936 937 // Check for ranges that start in the same G1 region in which the previous 938 // range ended, and adjust the start address so we don't try to free 939 // the same region again. If the current range is entirely within that 940 // region, skip it. 941 if (start_region == prev_last_region) { 942 start_address = start_region->end(); 943 if (start_address > last_address) { 944 continue; 945 } 946 start_region = _hrm.addr_to_region(start_address); 947 } 948 prev_last_region = last_region; 949 950 // After verifying that each region was marked as an archive region by 951 // alloc_archive_regions, set it free and empty and uncommit it. 952 HeapRegion* curr_region = start_region; 953 while (curr_region != NULL) { 954 guarantee(curr_region->is_archive(), 955 "Expected archive region at index %u", curr_region->hrm_index()); 956 uint curr_index = curr_region->hrm_index(); 957 _old_set.remove(curr_region); 958 curr_region->set_free(); 959 curr_region->set_top(curr_region->bottom()); 960 if (curr_region != last_region) { 961 curr_region = _hrm.next_region_in_heap(curr_region); 962 } else { 963 curr_region = NULL; 964 } 965 _hrm.shrink_at(curr_index, 1); 966 uncommitted_regions++; 967 } 968 969 // Notify mark-sweep that this is no longer an archive range. 970 G1MarkSweep::set_range_archive(ranges[i], false); 971 } 972 973 if (uncommitted_regions != 0) { 974 ergo_verbose1(ErgoHeapSizing, 975 "attempt heap shrinking", 976 ergo_format_reason("uncommitted archive regions") 977 ergo_format_byte("total size"), 978 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions); 979 } 980 decrease_used(size_used); 981 } 982 983 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size, 984 uint* gc_count_before_ret, 985 uint* gclocker_retry_count_ret) { 986 // The structure of this method has a lot of similarities to 987 // attempt_allocation_slow(). The reason these two were not merged 988 // into a single one is that such a method would require several "if 989 // allocation is not humongous do this, otherwise do that" 990 // conditional paths which would obscure its flow. In fact, an early 991 // version of this code did use a unified method which was harder to 992 // follow and, as a result, it had subtle bugs that were hard to 993 // track down. So keeping these two methods separate allows each to 994 // be more readable. It will be good to keep these two in sync as 995 // much as possible. 996 997 assert_heap_not_locked_and_not_at_safepoint(); 998 assert(is_humongous(word_size), "attempt_allocation_humongous() " 999 "should only be called for humongous allocations"); 1000 1001 // Humongous objects can exhaust the heap quickly, so we should check if we 1002 // need to start a marking cycle at each humongous object allocation. We do 1003 // the check before we do the actual allocation. The reason for doing it 1004 // before the allocation is that we avoid having to keep track of the newly 1005 // allocated memory while we do a GC. 1006 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation", 1007 word_size)) { 1008 collect(GCCause::_g1_humongous_allocation); 1009 } 1010 1011 // We will loop until a) we manage to successfully perform the 1012 // allocation or b) we successfully schedule a collection which 1013 // fails to perform the allocation. b) is the only case when we'll 1014 // return NULL. 1015 HeapWord* result = NULL; 1016 for (int try_count = 1; /* we'll return */; try_count += 1) { 1017 bool should_try_gc; 1018 uint gc_count_before; 1019 1020 { 1021 MutexLockerEx x(Heap_lock); 1022 1023 // Given that humongous objects are not allocated in young 1024 // regions, we'll first try to do the allocation without doing a 1025 // collection hoping that there's enough space in the heap. 1026 result = humongous_obj_allocate(word_size, AllocationContext::current()); 1027 if (result != NULL) { 1028 return result; 1029 } 1030 1031 if (GC_locker::is_active_and_needs_gc()) { 1032 should_try_gc = false; 1033 } else { 1034 // The GCLocker may not be active but the GCLocker initiated 1035 // GC may not yet have been performed (GCLocker::needs_gc() 1036 // returns true). In this case we do not try this GC and 1037 // wait until the GCLocker initiated GC is performed, and 1038 // then retry the allocation. 1039 if (GC_locker::needs_gc()) { 1040 should_try_gc = false; 1041 } else { 1042 // Read the GC count while still holding the Heap_lock. 1043 gc_count_before = total_collections(); 1044 should_try_gc = true; 1045 } 1046 } 1047 } 1048 1049 if (should_try_gc) { 1050 // If we failed to allocate the humongous object, we should try to 1051 // do a collection pause (if we're allowed) in case it reclaims 1052 // enough space for the allocation to succeed after the pause. 1053 1054 bool succeeded; 1055 result = do_collection_pause(word_size, gc_count_before, &succeeded, 1056 GCCause::_g1_humongous_allocation); 1057 if (result != NULL) { 1058 assert(succeeded, "only way to get back a non-NULL result"); 1059 return result; 1060 } 1061 1062 if (succeeded) { 1063 // If we get here we successfully scheduled a collection which 1064 // failed to allocate. No point in trying to allocate 1065 // further. We'll just return NULL. 1066 MutexLockerEx x(Heap_lock); 1067 *gc_count_before_ret = total_collections(); 1068 return NULL; 1069 } 1070 } else { 1071 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { 1072 MutexLockerEx x(Heap_lock); 1073 *gc_count_before_ret = total_collections(); 1074 return NULL; 1075 } 1076 // The GCLocker is either active or the GCLocker initiated 1077 // GC has not yet been performed. Stall until it is and 1078 // then retry the allocation. 1079 GC_locker::stall_until_clear(); 1080 (*gclocker_retry_count_ret) += 1; 1081 } 1082 1083 // We can reach here if we were unsuccessful in scheduling a 1084 // collection (because another thread beat us to it) or if we were 1085 // stalled due to the GC locker. In either can we should retry the 1086 // allocation attempt in case another thread successfully 1087 // performed a collection and reclaimed enough space. Give a 1088 // warning if we seem to be looping forever. 1089 1090 if ((QueuedAllocationWarningCount > 0) && 1091 (try_count % QueuedAllocationWarningCount == 0)) { 1092 warning("G1CollectedHeap::attempt_allocation_humongous() " 1093 "retries %d times", try_count); 1094 } 1095 } 1096 1097 ShouldNotReachHere(); 1098 return NULL; 1099 } 1100 1101 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size, 1102 AllocationContext_t context, 1103 bool expect_null_mutator_alloc_region) { 1104 assert_at_safepoint(true /* should_be_vm_thread */); 1105 assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region, 1106 "the current alloc region was unexpectedly found to be non-NULL"); 1107 1108 if (!is_humongous(word_size)) { 1109 return _allocator->attempt_allocation_locked(word_size, context); 1110 } else { 1111 HeapWord* result = humongous_obj_allocate(word_size, context); 1112 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) { 1113 collector_state()->set_initiate_conc_mark_if_possible(true); 1114 } 1115 return result; 1116 } 1117 1118 ShouldNotReachHere(); 1119 } 1120 1121 class PostMCRemSetClearClosure: public HeapRegionClosure { 1122 G1CollectedHeap* _g1h; 1123 ModRefBarrierSet* _mr_bs; 1124 public: 1125 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) : 1126 _g1h(g1h), _mr_bs(mr_bs) {} 1127 1128 bool doHeapRegion(HeapRegion* r) { 1129 HeapRegionRemSet* hrrs = r->rem_set(); 1130 1131 _g1h->reset_gc_time_stamps(r); 1132 1133 if (r->is_continues_humongous()) { 1134 // We'll assert that the strong code root list and RSet is empty 1135 assert(hrrs->strong_code_roots_list_length() == 0, "sanity"); 1136 assert(hrrs->occupied() == 0, "RSet should be empty"); 1137 return false; 1138 } 1139 1140 hrrs->clear(); 1141 // You might think here that we could clear just the cards 1142 // corresponding to the used region. But no: if we leave a dirty card 1143 // in a region we might allocate into, then it would prevent that card 1144 // from being enqueued, and cause it to be missed. 1145 // Re: the performance cost: we shouldn't be doing full GC anyway! 1146 _mr_bs->clear(MemRegion(r->bottom(), r->end())); 1147 1148 return false; 1149 } 1150 }; 1151 1152 void G1CollectedHeap::clear_rsets_post_compaction() { 1153 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set()); 1154 heap_region_iterate(&rs_clear); 1155 } 1156 1157 class RebuildRSOutOfRegionClosure: public HeapRegionClosure { 1158 G1CollectedHeap* _g1h; 1159 UpdateRSOopClosure _cl; 1160 public: 1161 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) : 1162 _cl(g1->g1_rem_set(), worker_i), 1163 _g1h(g1) 1164 { } 1165 1166 bool doHeapRegion(HeapRegion* r) { 1167 if (!r->is_continues_humongous()) { 1168 _cl.set_from(r); 1169 r->oop_iterate(&_cl); 1170 } 1171 return false; 1172 } 1173 }; 1174 1175 class ParRebuildRSTask: public AbstractGangTask { 1176 G1CollectedHeap* _g1; 1177 HeapRegionClaimer _hrclaimer; 1178 1179 public: 1180 ParRebuildRSTask(G1CollectedHeap* g1) : 1181 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {} 1182 1183 void work(uint worker_id) { 1184 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id); 1185 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer); 1186 } 1187 }; 1188 1189 class PostCompactionPrinterClosure: public HeapRegionClosure { 1190 private: 1191 G1HRPrinter* _hr_printer; 1192 public: 1193 bool doHeapRegion(HeapRegion* hr) { 1194 assert(!hr->is_young(), "not expecting to find young regions"); 1195 if (hr->is_free()) { 1196 // We only generate output for non-empty regions. 1197 } else if (hr->is_starts_humongous()) { 1198 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous); 1199 } else if (hr->is_continues_humongous()) { 1200 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous); 1201 } else if (hr->is_archive()) { 1202 _hr_printer->post_compaction(hr, G1HRPrinter::Archive); 1203 } else if (hr->is_old()) { 1204 _hr_printer->post_compaction(hr, G1HRPrinter::Old); 1205 } else { 1206 ShouldNotReachHere(); 1207 } 1208 return false; 1209 } 1210 1211 PostCompactionPrinterClosure(G1HRPrinter* hr_printer) 1212 : _hr_printer(hr_printer) { } 1213 }; 1214 1215 void G1CollectedHeap::print_hrm_post_compaction() { 1216 PostCompactionPrinterClosure cl(hr_printer()); 1217 heap_region_iterate(&cl); 1218 } 1219 1220 bool G1CollectedHeap::do_collection(bool explicit_gc, 1221 bool clear_all_soft_refs, 1222 size_t word_size) { 1223 assert_at_safepoint(true /* should_be_vm_thread */); 1224 1225 if (GC_locker::check_active_before_gc()) { 1226 return false; 1227 } 1228 1229 STWGCTimer* gc_timer = G1MarkSweep::gc_timer(); 1230 gc_timer->register_gc_start(); 1231 1232 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer(); 1233 GCIdMark gc_id_mark; 1234 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start()); 1235 1236 SvcGCMarker sgcm(SvcGCMarker::FULL); 1237 ResourceMark rm; 1238 1239 G1Log::update_level(); 1240 print_heap_before_gc(); 1241 trace_heap_before_gc(gc_tracer); 1242 1243 size_t metadata_prev_used = MetaspaceAux::used_bytes(); 1244 1245 verify_region_sets_optional(); 1246 1247 const bool do_clear_all_soft_refs = clear_all_soft_refs || 1248 collector_policy()->should_clear_all_soft_refs(); 1249 1250 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy()); 1251 1252 { 1253 IsGCActiveMark x; 1254 1255 // Timing 1256 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant"); 1257 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty); 1258 1259 { 1260 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL); 1261 TraceCollectorStats tcs(g1mm()->full_collection_counters()); 1262 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause()); 1263 1264 g1_policy()->record_full_collection_start(); 1265 1266 // Note: When we have a more flexible GC logging framework that 1267 // allows us to add optional attributes to a GC log record we 1268 // could consider timing and reporting how long we wait in the 1269 // following two methods. 1270 wait_while_free_regions_coming(); 1271 // If we start the compaction before the CM threads finish 1272 // scanning the root regions we might trip them over as we'll 1273 // be moving objects / updating references. So let's wait until 1274 // they are done. By telling them to abort, they should complete 1275 // early. 1276 _cm->root_regions()->abort(); 1277 _cm->root_regions()->wait_until_scan_finished(); 1278 append_secondary_free_list_if_not_empty_with_lock(); 1279 1280 gc_prologue(true); 1281 increment_total_collections(true /* full gc */); 1282 increment_old_marking_cycles_started(); 1283 1284 assert(used() == recalculate_used(), "Should be equal"); 1285 1286 verify_before_gc(); 1287 1288 check_bitmaps("Full GC Start"); 1289 pre_full_gc_dump(gc_timer); 1290 1291 #if defined(COMPILER2) || INCLUDE_JVMCI 1292 DerivedPointerTable::clear(); 1293 #endif 1294 1295 // Disable discovery and empty the discovered lists 1296 // for the CM ref processor. 1297 ref_processor_cm()->disable_discovery(); 1298 ref_processor_cm()->abandon_partial_discovery(); 1299 ref_processor_cm()->verify_no_references_recorded(); 1300 1301 // Abandon current iterations of concurrent marking and concurrent 1302 // refinement, if any are in progress. We have to do this before 1303 // wait_until_scan_finished() below. 1304 concurrent_mark()->abort(); 1305 1306 // Make sure we'll choose a new allocation region afterwards. 1307 _allocator->release_mutator_alloc_region(); 1308 _allocator->abandon_gc_alloc_regions(); 1309 g1_rem_set()->cleanupHRRS(); 1310 1311 // We should call this after we retire any currently active alloc 1312 // regions so that all the ALLOC / RETIRE events are generated 1313 // before the start GC event. 1314 _hr_printer.start_gc(true /* full */, (size_t) total_collections()); 1315 1316 // We may have added regions to the current incremental collection 1317 // set between the last GC or pause and now. We need to clear the 1318 // incremental collection set and then start rebuilding it afresh 1319 // after this full GC. 1320 abandon_collection_set(g1_policy()->inc_cset_head()); 1321 g1_policy()->clear_incremental_cset(); 1322 g1_policy()->stop_incremental_cset_building(); 1323 1324 tear_down_region_sets(false /* free_list_only */); 1325 collector_state()->set_gcs_are_young(true); 1326 1327 // See the comments in g1CollectedHeap.hpp and 1328 // G1CollectedHeap::ref_processing_init() about 1329 // how reference processing currently works in G1. 1330 1331 // Temporarily make discovery by the STW ref processor single threaded (non-MT). 1332 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false); 1333 1334 // Temporarily clear the STW ref processor's _is_alive_non_header field. 1335 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL); 1336 1337 ref_processor_stw()->enable_discovery(); 1338 ref_processor_stw()->setup_policy(do_clear_all_soft_refs); 1339 1340 // Do collection work 1341 { 1342 HandleMark hm; // Discard invalid handles created during gc 1343 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs); 1344 } 1345 1346 assert(num_free_regions() == 0, "we should not have added any free regions"); 1347 rebuild_region_sets(false /* free_list_only */); 1348 1349 // Enqueue any discovered reference objects that have 1350 // not been removed from the discovered lists. 1351 ref_processor_stw()->enqueue_discovered_references(); 1352 1353 #if defined(COMPILER2) || INCLUDE_JVMCI 1354 DerivedPointerTable::update_pointers(); 1355 #endif 1356 1357 MemoryService::track_memory_usage(); 1358 1359 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 1360 ref_processor_stw()->verify_no_references_recorded(); 1361 1362 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 1363 ClassLoaderDataGraph::purge(); 1364 MetaspaceAux::verify_metrics(); 1365 1366 // Note: since we've just done a full GC, concurrent 1367 // marking is no longer active. Therefore we need not 1368 // re-enable reference discovery for the CM ref processor. 1369 // That will be done at the start of the next marking cycle. 1370 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition"); 1371 ref_processor_cm()->verify_no_references_recorded(); 1372 1373 reset_gc_time_stamp(); 1374 // Since everything potentially moved, we will clear all remembered 1375 // sets, and clear all cards. Later we will rebuild remembered 1376 // sets. We will also reset the GC time stamps of the regions. 1377 clear_rsets_post_compaction(); 1378 check_gc_time_stamps(); 1379 1380 // Resize the heap if necessary. 1381 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size); 1382 1383 if (_hr_printer.is_active()) { 1384 // We should do this after we potentially resize the heap so 1385 // that all the COMMIT / UNCOMMIT events are generated before 1386 // the end GC event. 1387 1388 print_hrm_post_compaction(); 1389 _hr_printer.end_gc(true /* full */, (size_t) total_collections()); 1390 } 1391 1392 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 1393 if (hot_card_cache->use_cache()) { 1394 hot_card_cache->reset_card_counts(); 1395 hot_card_cache->reset_hot_cache(); 1396 } 1397 1398 // Rebuild remembered sets of all regions. 1399 uint n_workers = 1400 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 1401 workers()->active_workers(), 1402 Threads::number_of_non_daemon_threads()); 1403 workers()->set_active_workers(n_workers); 1404 1405 ParRebuildRSTask rebuild_rs_task(this); 1406 workers()->run_task(&rebuild_rs_task); 1407 1408 // Rebuild the strong code root lists for each region 1409 rebuild_strong_code_roots(); 1410 1411 if (true) { // FIXME 1412 MetaspaceGC::compute_new_size(); 1413 } 1414 1415 #ifdef TRACESPINNING 1416 ParallelTaskTerminator::print_termination_counts(); 1417 #endif 1418 1419 // Discard all rset updates 1420 JavaThread::dirty_card_queue_set().abandon_logs(); 1421 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty"); 1422 1423 _young_list->reset_sampled_info(); 1424 // At this point there should be no regions in the 1425 // entire heap tagged as young. 1426 assert(check_young_list_empty(true /* check_heap */), 1427 "young list should be empty at this point"); 1428 1429 // Update the number of full collections that have been completed. 1430 increment_old_marking_cycles_completed(false /* concurrent */); 1431 1432 _hrm.verify_optional(); 1433 verify_region_sets_optional(); 1434 1435 verify_after_gc(); 1436 1437 // Clear the previous marking bitmap, if needed for bitmap verification. 1438 // Note we cannot do this when we clear the next marking bitmap in 1439 // ConcurrentMark::abort() above since VerifyDuringGC verifies the 1440 // objects marked during a full GC against the previous bitmap. 1441 // But we need to clear it before calling check_bitmaps below since 1442 // the full GC has compacted objects and updated TAMS but not updated 1443 // the prev bitmap. 1444 if (G1VerifyBitmaps) { 1445 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll(); 1446 } 1447 check_bitmaps("Full GC End"); 1448 1449 // Start a new incremental collection set for the next pause 1450 assert(g1_policy()->collection_set() == NULL, "must be"); 1451 g1_policy()->start_incremental_cset_building(); 1452 1453 clear_cset_fast_test(); 1454 1455 _allocator->init_mutator_alloc_region(); 1456 1457 g1_policy()->record_full_collection_end(); 1458 1459 if (G1Log::fine()) { 1460 g1_policy()->print_heap_transition(); 1461 } 1462 1463 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 1464 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 1465 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 1466 // before any GC notifications are raised. 1467 g1mm()->update_sizes(); 1468 1469 gc_epilogue(true); 1470 } 1471 1472 if (G1Log::finer()) { 1473 g1_policy()->print_detailed_heap_transition(true /* full */); 1474 } 1475 1476 print_heap_after_gc(); 1477 trace_heap_after_gc(gc_tracer); 1478 1479 post_full_gc_dump(gc_timer); 1480 1481 gc_timer->register_gc_end(); 1482 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions()); 1483 } 1484 1485 return true; 1486 } 1487 1488 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) { 1489 // do_collection() will return whether it succeeded in performing 1490 // the GC. Currently, there is no facility on the 1491 // do_full_collection() API to notify the caller than the collection 1492 // did not succeed (e.g., because it was locked out by the GC 1493 // locker). So, right now, we'll ignore the return value. 1494 bool dummy = do_collection(true, /* explicit_gc */ 1495 clear_all_soft_refs, 1496 0 /* word_size */); 1497 } 1498 1499 // This code is mostly copied from TenuredGeneration. 1500 void 1501 G1CollectedHeap:: 1502 resize_if_necessary_after_full_collection(size_t word_size) { 1503 // Include the current allocation, if any, and bytes that will be 1504 // pre-allocated to support collections, as "used". 1505 const size_t used_after_gc = used(); 1506 const size_t capacity_after_gc = capacity(); 1507 const size_t free_after_gc = capacity_after_gc - used_after_gc; 1508 1509 // This is enforced in arguments.cpp. 1510 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, 1511 "otherwise the code below doesn't make sense"); 1512 1513 // We don't have floating point command-line arguments 1514 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0; 1515 const double maximum_used_percentage = 1.0 - minimum_free_percentage; 1516 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0; 1517 const double minimum_used_percentage = 1.0 - maximum_free_percentage; 1518 1519 const size_t min_heap_size = collector_policy()->min_heap_byte_size(); 1520 const size_t max_heap_size = collector_policy()->max_heap_byte_size(); 1521 1522 // We have to be careful here as these two calculations can overflow 1523 // 32-bit size_t's. 1524 double used_after_gc_d = (double) used_after_gc; 1525 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage; 1526 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage; 1527 1528 // Let's make sure that they are both under the max heap size, which 1529 // by default will make them fit into a size_t. 1530 double desired_capacity_upper_bound = (double) max_heap_size; 1531 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d, 1532 desired_capacity_upper_bound); 1533 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d, 1534 desired_capacity_upper_bound); 1535 1536 // We can now safely turn them into size_t's. 1537 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d; 1538 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d; 1539 1540 // This assert only makes sense here, before we adjust them 1541 // with respect to the min and max heap size. 1542 assert(minimum_desired_capacity <= maximum_desired_capacity, 1543 "minimum_desired_capacity = " SIZE_FORMAT ", " 1544 "maximum_desired_capacity = " SIZE_FORMAT, 1545 minimum_desired_capacity, maximum_desired_capacity); 1546 1547 // Should not be greater than the heap max size. No need to adjust 1548 // it with respect to the heap min size as it's a lower bound (i.e., 1549 // we'll try to make the capacity larger than it, not smaller). 1550 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size); 1551 // Should not be less than the heap min size. No need to adjust it 1552 // with respect to the heap max size as it's an upper bound (i.e., 1553 // we'll try to make the capacity smaller than it, not greater). 1554 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size); 1555 1556 if (capacity_after_gc < minimum_desired_capacity) { 1557 // Don't expand unless it's significant 1558 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc; 1559 ergo_verbose4(ErgoHeapSizing, 1560 "attempt heap expansion", 1561 ergo_format_reason("capacity lower than " 1562 "min desired capacity after Full GC") 1563 ergo_format_byte("capacity") 1564 ergo_format_byte("occupancy") 1565 ergo_format_byte_perc("min desired capacity"), 1566 capacity_after_gc, used_after_gc, 1567 minimum_desired_capacity, (double) MinHeapFreeRatio); 1568 expand(expand_bytes); 1569 1570 // No expansion, now see if we want to shrink 1571 } else if (capacity_after_gc > maximum_desired_capacity) { 1572 // Capacity too large, compute shrinking size 1573 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity; 1574 ergo_verbose4(ErgoHeapSizing, 1575 "attempt heap shrinking", 1576 ergo_format_reason("capacity higher than " 1577 "max desired capacity after Full GC") 1578 ergo_format_byte("capacity") 1579 ergo_format_byte("occupancy") 1580 ergo_format_byte_perc("max desired capacity"), 1581 capacity_after_gc, used_after_gc, 1582 maximum_desired_capacity, (double) MaxHeapFreeRatio); 1583 shrink(shrink_bytes); 1584 } 1585 } 1586 1587 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size, 1588 AllocationContext_t context, 1589 bool do_gc, 1590 bool clear_all_soft_refs, 1591 bool expect_null_mutator_alloc_region, 1592 bool* gc_succeeded) { 1593 *gc_succeeded = true; 1594 // Let's attempt the allocation first. 1595 HeapWord* result = 1596 attempt_allocation_at_safepoint(word_size, 1597 context, 1598 expect_null_mutator_alloc_region); 1599 if (result != NULL) { 1600 assert(*gc_succeeded, "sanity"); 1601 return result; 1602 } 1603 1604 // In a G1 heap, we're supposed to keep allocation from failing by 1605 // incremental pauses. Therefore, at least for now, we'll favor 1606 // expansion over collection. (This might change in the future if we can 1607 // do something smarter than full collection to satisfy a failed alloc.) 1608 result = expand_and_allocate(word_size, context); 1609 if (result != NULL) { 1610 assert(*gc_succeeded, "sanity"); 1611 return result; 1612 } 1613 1614 if (do_gc) { 1615 // Expansion didn't work, we'll try to do a Full GC. 1616 *gc_succeeded = do_collection(false, /* explicit_gc */ 1617 clear_all_soft_refs, 1618 word_size); 1619 } 1620 1621 return NULL; 1622 } 1623 1624 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size, 1625 AllocationContext_t context, 1626 bool* succeeded) { 1627 assert_at_safepoint(true /* should_be_vm_thread */); 1628 1629 // Attempts to allocate followed by Full GC. 1630 HeapWord* result = 1631 satisfy_failed_allocation_helper(word_size, 1632 context, 1633 true, /* do_gc */ 1634 false, /* clear_all_soft_refs */ 1635 false, /* expect_null_mutator_alloc_region */ 1636 succeeded); 1637 1638 if (result != NULL || !*succeeded) { 1639 return result; 1640 } 1641 1642 // Attempts to allocate followed by Full GC that will collect all soft references. 1643 result = satisfy_failed_allocation_helper(word_size, 1644 context, 1645 true, /* do_gc */ 1646 true, /* clear_all_soft_refs */ 1647 true, /* expect_null_mutator_alloc_region */ 1648 succeeded); 1649 1650 if (result != NULL || !*succeeded) { 1651 return result; 1652 } 1653 1654 // Attempts to allocate, no GC 1655 result = satisfy_failed_allocation_helper(word_size, 1656 context, 1657 false, /* do_gc */ 1658 false, /* clear_all_soft_refs */ 1659 true, /* expect_null_mutator_alloc_region */ 1660 succeeded); 1661 1662 if (result != NULL) { 1663 assert(*succeeded, "sanity"); 1664 return result; 1665 } 1666 1667 assert(!collector_policy()->should_clear_all_soft_refs(), 1668 "Flag should have been handled and cleared prior to this point"); 1669 1670 // What else? We might try synchronous finalization later. If the total 1671 // space available is large enough for the allocation, then a more 1672 // complete compaction phase than we've tried so far might be 1673 // appropriate. 1674 assert(*succeeded, "sanity"); 1675 return NULL; 1676 } 1677 1678 // Attempting to expand the heap sufficiently 1679 // to support an allocation of the given "word_size". If 1680 // successful, perform the allocation and return the address of the 1681 // allocated block, or else "NULL". 1682 1683 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) { 1684 assert_at_safepoint(true /* should_be_vm_thread */); 1685 1686 verify_region_sets_optional(); 1687 1688 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes); 1689 ergo_verbose1(ErgoHeapSizing, 1690 "attempt heap expansion", 1691 ergo_format_reason("allocation request failed") 1692 ergo_format_byte("allocation request"), 1693 word_size * HeapWordSize); 1694 if (expand(expand_bytes)) { 1695 _hrm.verify_optional(); 1696 verify_region_sets_optional(); 1697 return attempt_allocation_at_safepoint(word_size, 1698 context, 1699 false /* expect_null_mutator_alloc_region */); 1700 } 1701 return NULL; 1702 } 1703 1704 bool G1CollectedHeap::expand(size_t expand_bytes, double* expand_time_ms) { 1705 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); 1706 aligned_expand_bytes = align_size_up(aligned_expand_bytes, 1707 HeapRegion::GrainBytes); 1708 ergo_verbose2(ErgoHeapSizing, 1709 "expand the heap", 1710 ergo_format_byte("requested expansion amount") 1711 ergo_format_byte("attempted expansion amount"), 1712 expand_bytes, aligned_expand_bytes); 1713 1714 if (is_maximal_no_gc()) { 1715 ergo_verbose0(ErgoHeapSizing, 1716 "did not expand the heap", 1717 ergo_format_reason("heap already fully expanded")); 1718 return false; 1719 } 1720 1721 double expand_heap_start_time_sec = os::elapsedTime(); 1722 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes); 1723 assert(regions_to_expand > 0, "Must expand by at least one region"); 1724 1725 uint expanded_by = _hrm.expand_by(regions_to_expand); 1726 if (expand_time_ms != NULL) { 1727 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS; 1728 } 1729 1730 if (expanded_by > 0) { 1731 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes; 1732 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition"); 1733 g1_policy()->record_new_heap_size(num_regions()); 1734 } else { 1735 ergo_verbose0(ErgoHeapSizing, 1736 "did not expand the heap", 1737 ergo_format_reason("heap expansion operation failed")); 1738 // The expansion of the virtual storage space was unsuccessful. 1739 // Let's see if it was because we ran out of swap. 1740 if (G1ExitOnExpansionFailure && 1741 _hrm.available() >= regions_to_expand) { 1742 // We had head room... 1743 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion"); 1744 } 1745 } 1746 return regions_to_expand > 0; 1747 } 1748 1749 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) { 1750 size_t aligned_shrink_bytes = 1751 ReservedSpace::page_align_size_down(shrink_bytes); 1752 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes, 1753 HeapRegion::GrainBytes); 1754 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes); 1755 1756 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove); 1757 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes; 1758 1759 ergo_verbose3(ErgoHeapSizing, 1760 "shrink the heap", 1761 ergo_format_byte("requested shrinking amount") 1762 ergo_format_byte("aligned shrinking amount") 1763 ergo_format_byte("attempted shrinking amount"), 1764 shrink_bytes, aligned_shrink_bytes, shrunk_bytes); 1765 if (num_regions_removed > 0) { 1766 g1_policy()->record_new_heap_size(num_regions()); 1767 } else { 1768 ergo_verbose0(ErgoHeapSizing, 1769 "did not shrink the heap", 1770 ergo_format_reason("heap shrinking operation failed")); 1771 } 1772 } 1773 1774 void G1CollectedHeap::shrink(size_t shrink_bytes) { 1775 verify_region_sets_optional(); 1776 1777 // We should only reach here at the end of a Full GC which means we 1778 // should not not be holding to any GC alloc regions. The method 1779 // below will make sure of that and do any remaining clean up. 1780 _allocator->abandon_gc_alloc_regions(); 1781 1782 // Instead of tearing down / rebuilding the free lists here, we 1783 // could instead use the remove_all_pending() method on free_list to 1784 // remove only the ones that we need to remove. 1785 tear_down_region_sets(true /* free_list_only */); 1786 shrink_helper(shrink_bytes); 1787 rebuild_region_sets(true /* free_list_only */); 1788 1789 _hrm.verify_optional(); 1790 verify_region_sets_optional(); 1791 } 1792 1793 // Public methods. 1794 1795 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away 1796 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list 1797 #endif // _MSC_VER 1798 1799 1800 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) : 1801 CollectedHeap(), 1802 _g1_policy(policy_), 1803 _dirty_card_queue_set(false), 1804 _into_cset_dirty_card_queue_set(false), 1805 _is_alive_closure_cm(this), 1806 _is_alive_closure_stw(this), 1807 _ref_processor_cm(NULL), 1808 _ref_processor_stw(NULL), 1809 _bot_shared(NULL), 1810 _cg1r(NULL), 1811 _g1mm(NULL), 1812 _refine_cte_cl(NULL), 1813 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()), 1814 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()), 1815 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()), 1816 _humongous_reclaim_candidates(), 1817 _has_humongous_reclaim_candidates(false), 1818 _archive_allocator(NULL), 1819 _free_regions_coming(false), 1820 _young_list(new YoungList(this)), 1821 _gc_time_stamp(0), 1822 _summary_bytes_used(0), 1823 _survivor_evac_stats(YoungPLABSize, PLABWeight), 1824 _old_evac_stats(OldPLABSize, PLABWeight), 1825 _expand_heap_after_alloc_failure(true), 1826 _old_marking_cycles_started(0), 1827 _old_marking_cycles_completed(0), 1828 _heap_summary_sent(false), 1829 _in_cset_fast_test(), 1830 _dirty_cards_region_list(NULL), 1831 _worker_cset_start_region(NULL), 1832 _worker_cset_start_region_time_stamp(NULL), 1833 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()), 1834 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()), 1835 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()), 1836 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) { 1837 1838 _workers = new WorkGang("GC Thread", ParallelGCThreads, 1839 /* are_GC_task_threads */true, 1840 /* are_ConcurrentGC_threads */false); 1841 _workers->initialize_workers(); 1842 1843 _allocator = G1Allocator::create_allocator(this); 1844 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords); 1845 1846 // Override the default _filler_array_max_size so that no humongous filler 1847 // objects are created. 1848 _filler_array_max_size = _humongous_object_threshold_in_words; 1849 1850 uint n_queues = ParallelGCThreads; 1851 _task_queues = new RefToScanQueueSet(n_queues); 1852 1853 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets(); 1854 assert(n_rem_sets > 0, "Invariant."); 1855 1856 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC); 1857 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC); 1858 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC); 1859 1860 for (uint i = 0; i < n_queues; i++) { 1861 RefToScanQueue* q = new RefToScanQueue(); 1862 q->initialize(); 1863 _task_queues->register_queue(i, q); 1864 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo(); 1865 } 1866 clear_cset_start_regions(); 1867 1868 // Initialize the G1EvacuationFailureALot counters and flags. 1869 NOT_PRODUCT(reset_evacuation_should_fail();) 1870 1871 guarantee(_task_queues != NULL, "task_queues allocation failure."); 1872 } 1873 1874 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description, 1875 size_t size, 1876 size_t translation_factor) { 1877 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1); 1878 // Allocate a new reserved space, preferring to use large pages. 1879 ReservedSpace rs(size, preferred_page_size); 1880 G1RegionToSpaceMapper* result = 1881 G1RegionToSpaceMapper::create_mapper(rs, 1882 size, 1883 rs.alignment(), 1884 HeapRegion::GrainBytes, 1885 translation_factor, 1886 mtGC); 1887 if (TracePageSizes) { 1888 gclog_or_tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT, 1889 description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size); 1890 } 1891 return result; 1892 } 1893 1894 jint G1CollectedHeap::initialize() { 1895 CollectedHeap::pre_initialize(); 1896 os::enable_vtime(); 1897 1898 G1Log::init(); 1899 1900 // Necessary to satisfy locking discipline assertions. 1901 1902 MutexLocker x(Heap_lock); 1903 1904 // We have to initialize the printer before committing the heap, as 1905 // it will be used then. 1906 _hr_printer.set_active(G1PrintHeapRegions); 1907 1908 // While there are no constraints in the GC code that HeapWordSize 1909 // be any particular value, there are multiple other areas in the 1910 // system which believe this to be true (e.g. oop->object_size in some 1911 // cases incorrectly returns the size in wordSize units rather than 1912 // HeapWordSize). 1913 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 1914 1915 size_t init_byte_size = collector_policy()->initial_heap_byte_size(); 1916 size_t max_byte_size = collector_policy()->max_heap_byte_size(); 1917 size_t heap_alignment = collector_policy()->heap_alignment(); 1918 1919 // Ensure that the sizes are properly aligned. 1920 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1921 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1922 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap"); 1923 1924 _refine_cte_cl = new RefineCardTableEntryClosure(); 1925 1926 jint ecode = JNI_OK; 1927 _cg1r = ConcurrentG1Refine::create(this, _refine_cte_cl, &ecode); 1928 if (_cg1r == NULL) { 1929 return ecode; 1930 } 1931 1932 // Reserve the maximum. 1933 1934 // When compressed oops are enabled, the preferred heap base 1935 // is calculated by subtracting the requested size from the 1936 // 32Gb boundary and using the result as the base address for 1937 // heap reservation. If the requested size is not aligned to 1938 // HeapRegion::GrainBytes (i.e. the alignment that is passed 1939 // into the ReservedHeapSpace constructor) then the actual 1940 // base of the reserved heap may end up differing from the 1941 // address that was requested (i.e. the preferred heap base). 1942 // If this happens then we could end up using a non-optimal 1943 // compressed oops mode. 1944 1945 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size, 1946 heap_alignment); 1947 1948 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size())); 1949 1950 // Create the barrier set for the entire reserved region. 1951 G1SATBCardTableLoggingModRefBS* bs 1952 = new G1SATBCardTableLoggingModRefBS(reserved_region()); 1953 bs->initialize(); 1954 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity"); 1955 set_barrier_set(bs); 1956 1957 // Also create a G1 rem set. 1958 _g1_rem_set = new G1RemSet(this, g1_barrier_set()); 1959 1960 // Carve out the G1 part of the heap. 1961 1962 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size); 1963 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size(); 1964 G1RegionToSpaceMapper* heap_storage = 1965 G1RegionToSpaceMapper::create_mapper(g1_rs, 1966 g1_rs.size(), 1967 page_size, 1968 HeapRegion::GrainBytes, 1969 1, 1970 mtJavaHeap); 1971 os::trace_page_sizes("G1 Heap", collector_policy()->min_heap_byte_size(), 1972 max_byte_size, page_size, 1973 heap_rs.base(), 1974 heap_rs.size()); 1975 heap_storage->set_mapping_changed_listener(&_listener); 1976 1977 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps. 1978 G1RegionToSpaceMapper* bot_storage = 1979 create_aux_memory_mapper("Block offset table", 1980 G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize), 1981 G1BlockOffsetSharedArray::heap_map_factor()); 1982 1983 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize)); 1984 G1RegionToSpaceMapper* cardtable_storage = 1985 create_aux_memory_mapper("Card table", 1986 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize), 1987 G1SATBCardTableLoggingModRefBS::heap_map_factor()); 1988 1989 G1RegionToSpaceMapper* card_counts_storage = 1990 create_aux_memory_mapper("Card counts table", 1991 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize), 1992 G1CardCounts::heap_map_factor()); 1993 1994 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size()); 1995 G1RegionToSpaceMapper* prev_bitmap_storage = 1996 create_aux_memory_mapper("Prev Bitmap", bitmap_size, CMBitMap::heap_map_factor()); 1997 G1RegionToSpaceMapper* next_bitmap_storage = 1998 create_aux_memory_mapper("Next Bitmap", bitmap_size, CMBitMap::heap_map_factor()); 1999 2000 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage); 2001 g1_barrier_set()->initialize(cardtable_storage); 2002 // Do later initialization work for concurrent refinement. 2003 _cg1r->init(card_counts_storage); 2004 2005 // 6843694 - ensure that the maximum region index can fit 2006 // in the remembered set structures. 2007 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; 2008 guarantee((max_regions() - 1) <= max_region_idx, "too many regions"); 2009 2010 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; 2011 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); 2012 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region, 2013 "too many cards per region"); 2014 2015 FreeRegionList::set_unrealistically_long_length(max_regions() + 1); 2016 2017 _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage); 2018 2019 { 2020 HeapWord* start = _hrm.reserved().start(); 2021 HeapWord* end = _hrm.reserved().end(); 2022 size_t granularity = HeapRegion::GrainBytes; 2023 2024 _in_cset_fast_test.initialize(start, end, granularity); 2025 _humongous_reclaim_candidates.initialize(start, end, granularity); 2026 } 2027 2028 // Create the ConcurrentMark data structure and thread. 2029 // (Must do this late, so that "max_regions" is defined.) 2030 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage); 2031 if (_cm == NULL || !_cm->completed_initialization()) { 2032 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark"); 2033 return JNI_ENOMEM; 2034 } 2035 _cmThread = _cm->cmThread(); 2036 2037 // Initialize the from_card cache structure of HeapRegionRemSet. 2038 HeapRegionRemSet::init_heap(max_regions()); 2039 2040 // Now expand into the initial heap size. 2041 if (!expand(init_byte_size)) { 2042 vm_shutdown_during_initialization("Failed to allocate initial heap."); 2043 return JNI_ENOMEM; 2044 } 2045 2046 // Perform any initialization actions delegated to the policy. 2047 g1_policy()->init(); 2048 2049 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon, 2050 SATB_Q_FL_lock, 2051 G1SATBProcessCompletedThreshold, 2052 Shared_SATB_Q_lock); 2053 2054 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl, 2055 DirtyCardQ_CBL_mon, 2056 DirtyCardQ_FL_lock, 2057 concurrent_g1_refine()->yellow_zone(), 2058 concurrent_g1_refine()->red_zone(), 2059 Shared_DirtyCardQ_lock); 2060 2061 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code 2062 DirtyCardQ_CBL_mon, 2063 DirtyCardQ_FL_lock, 2064 -1, // never trigger processing 2065 -1, // no limit on length 2066 Shared_DirtyCardQ_lock, 2067 &JavaThread::dirty_card_queue_set()); 2068 2069 // Initialize the card queue set used to hold cards containing 2070 // references into the collection set. 2071 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code 2072 DirtyCardQ_CBL_mon, 2073 DirtyCardQ_FL_lock, 2074 -1, // never trigger processing 2075 -1, // no limit on length 2076 Shared_DirtyCardQ_lock, 2077 &JavaThread::dirty_card_queue_set()); 2078 2079 // Here we allocate the dummy HeapRegion that is required by the 2080 // G1AllocRegion class. 2081 HeapRegion* dummy_region = _hrm.get_dummy_region(); 2082 2083 // We'll re-use the same region whether the alloc region will 2084 // require BOT updates or not and, if it doesn't, then a non-young 2085 // region will complain that it cannot support allocations without 2086 // BOT updates. So we'll tag the dummy region as eden to avoid that. 2087 dummy_region->set_eden(); 2088 // Make sure it's full. 2089 dummy_region->set_top(dummy_region->end()); 2090 G1AllocRegion::setup(this, dummy_region); 2091 2092 _allocator->init_mutator_alloc_region(); 2093 2094 // Do create of the monitoring and management support so that 2095 // values in the heap have been properly initialized. 2096 _g1mm = new G1MonitoringSupport(this); 2097 2098 G1StringDedup::initialize(); 2099 2100 _preserved_objs = NEW_C_HEAP_ARRAY(OopAndMarkOopStack, ParallelGCThreads, mtGC); 2101 for (uint i = 0; i < ParallelGCThreads; i++) { 2102 new (&_preserved_objs[i]) OopAndMarkOopStack(); 2103 } 2104 2105 return JNI_OK; 2106 } 2107 2108 void G1CollectedHeap::stop() { 2109 // Stop all concurrent threads. We do this to make sure these threads 2110 // do not continue to execute and access resources (e.g. gclog_or_tty) 2111 // that are destroyed during shutdown. 2112 _cg1r->stop(); 2113 _cmThread->stop(); 2114 if (G1StringDedup::is_enabled()) { 2115 G1StringDedup::stop(); 2116 } 2117 } 2118 2119 size_t G1CollectedHeap::conservative_max_heap_alignment() { 2120 return HeapRegion::max_region_size(); 2121 } 2122 2123 void G1CollectedHeap::post_initialize() { 2124 CollectedHeap::post_initialize(); 2125 ref_processing_init(); 2126 } 2127 2128 void G1CollectedHeap::ref_processing_init() { 2129 // Reference processing in G1 currently works as follows: 2130 // 2131 // * There are two reference processor instances. One is 2132 // used to record and process discovered references 2133 // during concurrent marking; the other is used to 2134 // record and process references during STW pauses 2135 // (both full and incremental). 2136 // * Both ref processors need to 'span' the entire heap as 2137 // the regions in the collection set may be dotted around. 2138 // 2139 // * For the concurrent marking ref processor: 2140 // * Reference discovery is enabled at initial marking. 2141 // * Reference discovery is disabled and the discovered 2142 // references processed etc during remarking. 2143 // * Reference discovery is MT (see below). 2144 // * Reference discovery requires a barrier (see below). 2145 // * Reference processing may or may not be MT 2146 // (depending on the value of ParallelRefProcEnabled 2147 // and ParallelGCThreads). 2148 // * A full GC disables reference discovery by the CM 2149 // ref processor and abandons any entries on it's 2150 // discovered lists. 2151 // 2152 // * For the STW processor: 2153 // * Non MT discovery is enabled at the start of a full GC. 2154 // * Processing and enqueueing during a full GC is non-MT. 2155 // * During a full GC, references are processed after marking. 2156 // 2157 // * Discovery (may or may not be MT) is enabled at the start 2158 // of an incremental evacuation pause. 2159 // * References are processed near the end of a STW evacuation pause. 2160 // * For both types of GC: 2161 // * Discovery is atomic - i.e. not concurrent. 2162 // * Reference discovery will not need a barrier. 2163 2164 MemRegion mr = reserved_region(); 2165 2166 // Concurrent Mark ref processor 2167 _ref_processor_cm = 2168 new ReferenceProcessor(mr, // span 2169 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2170 // mt processing 2171 ParallelGCThreads, 2172 // degree of mt processing 2173 (ParallelGCThreads > 1) || (ConcGCThreads > 1), 2174 // mt discovery 2175 MAX2(ParallelGCThreads, ConcGCThreads), 2176 // degree of mt discovery 2177 false, 2178 // Reference discovery is not atomic 2179 &_is_alive_closure_cm); 2180 // is alive closure 2181 // (for efficiency/performance) 2182 2183 // STW ref processor 2184 _ref_processor_stw = 2185 new ReferenceProcessor(mr, // span 2186 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2187 // mt processing 2188 ParallelGCThreads, 2189 // degree of mt processing 2190 (ParallelGCThreads > 1), 2191 // mt discovery 2192 ParallelGCThreads, 2193 // degree of mt discovery 2194 true, 2195 // Reference discovery is atomic 2196 &_is_alive_closure_stw); 2197 // is alive closure 2198 // (for efficiency/performance) 2199 } 2200 2201 CollectorPolicy* G1CollectedHeap::collector_policy() const { 2202 return g1_policy(); 2203 } 2204 2205 size_t G1CollectedHeap::capacity() const { 2206 return _hrm.length() * HeapRegion::GrainBytes; 2207 } 2208 2209 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) { 2210 hr->reset_gc_time_stamp(); 2211 } 2212 2213 #ifndef PRODUCT 2214 2215 class CheckGCTimeStampsHRClosure : public HeapRegionClosure { 2216 private: 2217 unsigned _gc_time_stamp; 2218 bool _failures; 2219 2220 public: 2221 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) : 2222 _gc_time_stamp(gc_time_stamp), _failures(false) { } 2223 2224 virtual bool doHeapRegion(HeapRegion* hr) { 2225 unsigned region_gc_time_stamp = hr->get_gc_time_stamp(); 2226 if (_gc_time_stamp != region_gc_time_stamp) { 2227 gclog_or_tty->print_cr("Region " HR_FORMAT " has GC time stamp = %d, " 2228 "expected %d", HR_FORMAT_PARAMS(hr), 2229 region_gc_time_stamp, _gc_time_stamp); 2230 _failures = true; 2231 } 2232 return false; 2233 } 2234 2235 bool failures() { return _failures; } 2236 }; 2237 2238 void G1CollectedHeap::check_gc_time_stamps() { 2239 CheckGCTimeStampsHRClosure cl(_gc_time_stamp); 2240 heap_region_iterate(&cl); 2241 guarantee(!cl.failures(), "all GC time stamps should have been reset"); 2242 } 2243 #endif // PRODUCT 2244 2245 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) { 2246 _cg1r->hot_card_cache()->drain(cl, worker_i); 2247 } 2248 2249 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) { 2250 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 2251 size_t n_completed_buffers = 0; 2252 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) { 2253 n_completed_buffers++; 2254 } 2255 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers); 2256 dcqs.clear_n_completed_buffers(); 2257 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!"); 2258 } 2259 2260 // Computes the sum of the storage used by the various regions. 2261 size_t G1CollectedHeap::used() const { 2262 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions(); 2263 if (_archive_allocator != NULL) { 2264 result += _archive_allocator->used(); 2265 } 2266 return result; 2267 } 2268 2269 size_t G1CollectedHeap::used_unlocked() const { 2270 return _summary_bytes_used; 2271 } 2272 2273 class SumUsedClosure: public HeapRegionClosure { 2274 size_t _used; 2275 public: 2276 SumUsedClosure() : _used(0) {} 2277 bool doHeapRegion(HeapRegion* r) { 2278 _used += r->used(); 2279 return false; 2280 } 2281 size_t result() { return _used; } 2282 }; 2283 2284 size_t G1CollectedHeap::recalculate_used() const { 2285 double recalculate_used_start = os::elapsedTime(); 2286 2287 SumUsedClosure blk; 2288 heap_region_iterate(&blk); 2289 2290 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0); 2291 return blk.result(); 2292 } 2293 2294 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 2295 switch (cause) { 2296 case GCCause::_gc_locker: return GCLockerInvokesConcurrent; 2297 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent; 2298 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent; 2299 case GCCause::_g1_humongous_allocation: return true; 2300 case GCCause::_update_allocation_context_stats_inc: return true; 2301 case GCCause::_wb_conc_mark: return true; 2302 default: return false; 2303 } 2304 } 2305 2306 #ifndef PRODUCT 2307 void G1CollectedHeap::allocate_dummy_regions() { 2308 // Let's fill up most of the region 2309 size_t word_size = HeapRegion::GrainWords - 1024; 2310 // And as a result the region we'll allocate will be humongous. 2311 guarantee(is_humongous(word_size), "sanity"); 2312 2313 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) { 2314 // Let's use the existing mechanism for the allocation 2315 HeapWord* dummy_obj = humongous_obj_allocate(word_size, 2316 AllocationContext::system()); 2317 if (dummy_obj != NULL) { 2318 MemRegion mr(dummy_obj, word_size); 2319 CollectedHeap::fill_with_object(mr); 2320 } else { 2321 // If we can't allocate once, we probably cannot allocate 2322 // again. Let's get out of the loop. 2323 break; 2324 } 2325 } 2326 } 2327 #endif // !PRODUCT 2328 2329 void G1CollectedHeap::increment_old_marking_cycles_started() { 2330 assert(_old_marking_cycles_started == _old_marking_cycles_completed || 2331 _old_marking_cycles_started == _old_marking_cycles_completed + 1, 2332 "Wrong marking cycle count (started: %d, completed: %d)", 2333 _old_marking_cycles_started, _old_marking_cycles_completed); 2334 2335 _old_marking_cycles_started++; 2336 } 2337 2338 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) { 2339 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 2340 2341 // We assume that if concurrent == true, then the caller is a 2342 // concurrent thread that was joined the Suspendible Thread 2343 // Set. If there's ever a cheap way to check this, we should add an 2344 // assert here. 2345 2346 // Given that this method is called at the end of a Full GC or of a 2347 // concurrent cycle, and those can be nested (i.e., a Full GC can 2348 // interrupt a concurrent cycle), the number of full collections 2349 // completed should be either one (in the case where there was no 2350 // nesting) or two (when a Full GC interrupted a concurrent cycle) 2351 // behind the number of full collections started. 2352 2353 // This is the case for the inner caller, i.e. a Full GC. 2354 assert(concurrent || 2355 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || 2356 (_old_marking_cycles_started == _old_marking_cycles_completed + 2), 2357 "for inner caller (Full GC): _old_marking_cycles_started = %u " 2358 "is inconsistent with _old_marking_cycles_completed = %u", 2359 _old_marking_cycles_started, _old_marking_cycles_completed); 2360 2361 // This is the case for the outer caller, i.e. the concurrent cycle. 2362 assert(!concurrent || 2363 (_old_marking_cycles_started == _old_marking_cycles_completed + 1), 2364 "for outer caller (concurrent cycle): " 2365 "_old_marking_cycles_started = %u " 2366 "is inconsistent with _old_marking_cycles_completed = %u", 2367 _old_marking_cycles_started, _old_marking_cycles_completed); 2368 2369 _old_marking_cycles_completed += 1; 2370 2371 // We need to clear the "in_progress" flag in the CM thread before 2372 // we wake up any waiters (especially when ExplicitInvokesConcurrent 2373 // is set) so that if a waiter requests another System.gc() it doesn't 2374 // incorrectly see that a marking cycle is still in progress. 2375 if (concurrent) { 2376 _cmThread->set_idle(); 2377 } 2378 2379 // This notify_all() will ensure that a thread that called 2380 // System.gc() with (with ExplicitGCInvokesConcurrent set or not) 2381 // and it's waiting for a full GC to finish will be woken up. It is 2382 // waiting in VM_G1IncCollectionPause::doit_epilogue(). 2383 FullGCCount_lock->notify_all(); 2384 } 2385 2386 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) { 2387 GCIdMarkAndRestore conc_gc_id_mark; 2388 collector_state()->set_concurrent_cycle_started(true); 2389 _gc_timer_cm->register_gc_start(start_time); 2390 2391 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start()); 2392 trace_heap_before_gc(_gc_tracer_cm); 2393 _cmThread->set_gc_id(GCId::current()); 2394 } 2395 2396 void G1CollectedHeap::register_concurrent_cycle_end() { 2397 if (collector_state()->concurrent_cycle_started()) { 2398 GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id()); 2399 if (_cm->has_aborted()) { 2400 _gc_tracer_cm->report_concurrent_mode_failure(); 2401 } 2402 2403 _gc_timer_cm->register_gc_end(); 2404 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions()); 2405 2406 // Clear state variables to prepare for the next concurrent cycle. 2407 collector_state()->set_concurrent_cycle_started(false); 2408 _heap_summary_sent = false; 2409 } 2410 } 2411 2412 void G1CollectedHeap::trace_heap_after_concurrent_cycle() { 2413 if (collector_state()->concurrent_cycle_started()) { 2414 // This function can be called when: 2415 // the cleanup pause is run 2416 // the concurrent cycle is aborted before the cleanup pause. 2417 // the concurrent cycle is aborted after the cleanup pause, 2418 // but before the concurrent cycle end has been registered. 2419 // Make sure that we only send the heap information once. 2420 if (!_heap_summary_sent) { 2421 GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id()); 2422 trace_heap_after_gc(_gc_tracer_cm); 2423 _heap_summary_sent = true; 2424 } 2425 } 2426 } 2427 2428 void G1CollectedHeap::collect(GCCause::Cause cause) { 2429 assert_heap_not_locked(); 2430 2431 uint gc_count_before; 2432 uint old_marking_count_before; 2433 uint full_gc_count_before; 2434 bool retry_gc; 2435 2436 do { 2437 retry_gc = false; 2438 2439 { 2440 MutexLocker ml(Heap_lock); 2441 2442 // Read the GC count while holding the Heap_lock 2443 gc_count_before = total_collections(); 2444 full_gc_count_before = total_full_collections(); 2445 old_marking_count_before = _old_marking_cycles_started; 2446 } 2447 2448 if (should_do_concurrent_full_gc(cause)) { 2449 // Schedule an initial-mark evacuation pause that will start a 2450 // concurrent cycle. We're setting word_size to 0 which means that 2451 // we are not requesting a post-GC allocation. 2452 VM_G1IncCollectionPause op(gc_count_before, 2453 0, /* word_size */ 2454 true, /* should_initiate_conc_mark */ 2455 g1_policy()->max_pause_time_ms(), 2456 cause); 2457 op.set_allocation_context(AllocationContext::current()); 2458 2459 VMThread::execute(&op); 2460 if (!op.pause_succeeded()) { 2461 if (old_marking_count_before == _old_marking_cycles_started) { 2462 retry_gc = op.should_retry_gc(); 2463 } else { 2464 // A Full GC happened while we were trying to schedule the 2465 // initial-mark GC. No point in starting a new cycle given 2466 // that the whole heap was collected anyway. 2467 } 2468 2469 if (retry_gc) { 2470 if (GC_locker::is_active_and_needs_gc()) { 2471 GC_locker::stall_until_clear(); 2472 } 2473 } 2474 } 2475 } else { 2476 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc 2477 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { 2478 2479 // Schedule a standard evacuation pause. We're setting word_size 2480 // to 0 which means that we are not requesting a post-GC allocation. 2481 VM_G1IncCollectionPause op(gc_count_before, 2482 0, /* word_size */ 2483 false, /* should_initiate_conc_mark */ 2484 g1_policy()->max_pause_time_ms(), 2485 cause); 2486 VMThread::execute(&op); 2487 } else { 2488 // Schedule a Full GC. 2489 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause); 2490 VMThread::execute(&op); 2491 } 2492 } 2493 } while (retry_gc); 2494 } 2495 2496 bool G1CollectedHeap::is_in(const void* p) const { 2497 if (_hrm.reserved().contains(p)) { 2498 // Given that we know that p is in the reserved space, 2499 // heap_region_containing() should successfully 2500 // return the containing region. 2501 HeapRegion* hr = heap_region_containing(p); 2502 return hr->is_in(p); 2503 } else { 2504 return false; 2505 } 2506 } 2507 2508 #ifdef ASSERT 2509 bool G1CollectedHeap::is_in_exact(const void* p) const { 2510 bool contains = reserved_region().contains(p); 2511 bool available = _hrm.is_available(addr_to_region((HeapWord*)p)); 2512 if (contains && available) { 2513 return true; 2514 } else { 2515 return false; 2516 } 2517 } 2518 #endif 2519 2520 bool G1CollectedHeap::obj_in_cs(oop obj) { 2521 HeapRegion* r = _hrm.addr_to_region((HeapWord*) obj); 2522 return r != NULL && r->in_collection_set(); 2523 } 2524 2525 // Iteration functions. 2526 2527 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion. 2528 2529 class IterateOopClosureRegionClosure: public HeapRegionClosure { 2530 ExtendedOopClosure* _cl; 2531 public: 2532 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {} 2533 bool doHeapRegion(HeapRegion* r) { 2534 if (!r->is_continues_humongous()) { 2535 r->oop_iterate(_cl); 2536 } 2537 return false; 2538 } 2539 }; 2540 2541 // Iterates an ObjectClosure over all objects within a HeapRegion. 2542 2543 class IterateObjectClosureRegionClosure: public HeapRegionClosure { 2544 ObjectClosure* _cl; 2545 public: 2546 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} 2547 bool doHeapRegion(HeapRegion* r) { 2548 if (!r->is_continues_humongous()) { 2549 r->object_iterate(_cl); 2550 } 2551 return false; 2552 } 2553 }; 2554 2555 void G1CollectedHeap::object_iterate(ObjectClosure* cl) { 2556 IterateObjectClosureRegionClosure blk(cl); 2557 heap_region_iterate(&blk); 2558 } 2559 2560 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { 2561 _hrm.iterate(cl); 2562 } 2563 2564 void 2565 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl, 2566 uint worker_id, 2567 HeapRegionClaimer *hrclaimer, 2568 bool concurrent) const { 2569 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent); 2570 } 2571 2572 // Clear the cached CSet starting regions and (more importantly) 2573 // the time stamps. Called when we reset the GC time stamp. 2574 void G1CollectedHeap::clear_cset_start_regions() { 2575 assert(_worker_cset_start_region != NULL, "sanity"); 2576 assert(_worker_cset_start_region_time_stamp != NULL, "sanity"); 2577 2578 for (uint i = 0; i < ParallelGCThreads; i++) { 2579 _worker_cset_start_region[i] = NULL; 2580 _worker_cset_start_region_time_stamp[i] = 0; 2581 } 2582 } 2583 2584 // Given the id of a worker, obtain or calculate a suitable 2585 // starting region for iterating over the current collection set. 2586 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) { 2587 assert(get_gc_time_stamp() > 0, "should have been updated by now"); 2588 2589 HeapRegion* result = NULL; 2590 unsigned gc_time_stamp = get_gc_time_stamp(); 2591 2592 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) { 2593 // Cached starting region for current worker was set 2594 // during the current pause - so it's valid. 2595 // Note: the cached starting heap region may be NULL 2596 // (when the collection set is empty). 2597 result = _worker_cset_start_region[worker_i]; 2598 assert(result == NULL || result->in_collection_set(), "sanity"); 2599 return result; 2600 } 2601 2602 // The cached entry was not valid so let's calculate 2603 // a suitable starting heap region for this worker. 2604 2605 // We want the parallel threads to start their collection 2606 // set iteration at different collection set regions to 2607 // avoid contention. 2608 // If we have: 2609 // n collection set regions 2610 // p threads 2611 // Then thread t will start at region floor ((t * n) / p) 2612 2613 result = g1_policy()->collection_set(); 2614 uint cs_size = g1_policy()->cset_region_length(); 2615 uint active_workers = workers()->active_workers(); 2616 2617 uint end_ind = (cs_size * worker_i) / active_workers; 2618 uint start_ind = 0; 2619 2620 if (worker_i > 0 && 2621 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) { 2622 // Previous workers starting region is valid 2623 // so let's iterate from there 2624 start_ind = (cs_size * (worker_i - 1)) / active_workers; 2625 result = _worker_cset_start_region[worker_i - 1]; 2626 } 2627 2628 for (uint i = start_ind; i < end_ind; i++) { 2629 result = result->next_in_collection_set(); 2630 } 2631 2632 // Note: the calculated starting heap region may be NULL 2633 // (when the collection set is empty). 2634 assert(result == NULL || result->in_collection_set(), "sanity"); 2635 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp, 2636 "should be updated only once per pause"); 2637 _worker_cset_start_region[worker_i] = result; 2638 OrderAccess::storestore(); 2639 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp; 2640 return result; 2641 } 2642 2643 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) { 2644 HeapRegion* r = g1_policy()->collection_set(); 2645 while (r != NULL) { 2646 HeapRegion* next = r->next_in_collection_set(); 2647 if (cl->doHeapRegion(r)) { 2648 cl->incomplete(); 2649 return; 2650 } 2651 r = next; 2652 } 2653 } 2654 2655 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r, 2656 HeapRegionClosure *cl) { 2657 if (r == NULL) { 2658 // The CSet is empty so there's nothing to do. 2659 return; 2660 } 2661 2662 assert(r->in_collection_set(), 2663 "Start region must be a member of the collection set."); 2664 HeapRegion* cur = r; 2665 while (cur != NULL) { 2666 HeapRegion* next = cur->next_in_collection_set(); 2667 if (cl->doHeapRegion(cur) && false) { 2668 cl->incomplete(); 2669 return; 2670 } 2671 cur = next; 2672 } 2673 cur = g1_policy()->collection_set(); 2674 while (cur != r) { 2675 HeapRegion* next = cur->next_in_collection_set(); 2676 if (cl->doHeapRegion(cur) && false) { 2677 cl->incomplete(); 2678 return; 2679 } 2680 cur = next; 2681 } 2682 } 2683 2684 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const { 2685 HeapRegion* result = _hrm.next_region_in_heap(from); 2686 while (result != NULL && result->is_pinned()) { 2687 result = _hrm.next_region_in_heap(result); 2688 } 2689 return result; 2690 } 2691 2692 HeapWord* G1CollectedHeap::block_start(const void* addr) const { 2693 HeapRegion* hr = heap_region_containing(addr); 2694 return hr->block_start(addr); 2695 } 2696 2697 size_t G1CollectedHeap::block_size(const HeapWord* addr) const { 2698 HeapRegion* hr = heap_region_containing(addr); 2699 return hr->block_size(addr); 2700 } 2701 2702 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { 2703 HeapRegion* hr = heap_region_containing(addr); 2704 return hr->block_is_obj(addr); 2705 } 2706 2707 bool G1CollectedHeap::supports_tlab_allocation() const { 2708 return true; 2709 } 2710 2711 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { 2712 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes; 2713 } 2714 2715 size_t G1CollectedHeap::tlab_used(Thread* ignored) const { 2716 return young_list()->eden_used_bytes(); 2717 } 2718 2719 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size 2720 // must be equal to the humongous object limit. 2721 size_t G1CollectedHeap::max_tlab_size() const { 2722 return align_size_down(_humongous_object_threshold_in_words, MinObjAlignment); 2723 } 2724 2725 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { 2726 AllocationContext_t context = AllocationContext::current(); 2727 return _allocator->unsafe_max_tlab_alloc(context); 2728 } 2729 2730 size_t G1CollectedHeap::max_capacity() const { 2731 return _hrm.reserved().byte_size(); 2732 } 2733 2734 jlong G1CollectedHeap::millis_since_last_gc() { 2735 // assert(false, "NYI"); 2736 return 0; 2737 } 2738 2739 void G1CollectedHeap::prepare_for_verify() { 2740 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) { 2741 ensure_parsability(false); 2742 } 2743 g1_rem_set()->prepare_for_verify(); 2744 } 2745 2746 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr, 2747 VerifyOption vo) { 2748 switch (vo) { 2749 case VerifyOption_G1UsePrevMarking: 2750 return hr->obj_allocated_since_prev_marking(obj); 2751 case VerifyOption_G1UseNextMarking: 2752 return hr->obj_allocated_since_next_marking(obj); 2753 case VerifyOption_G1UseMarkWord: 2754 return false; 2755 default: 2756 ShouldNotReachHere(); 2757 } 2758 return false; // keep some compilers happy 2759 } 2760 2761 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) { 2762 switch (vo) { 2763 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start(); 2764 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start(); 2765 case VerifyOption_G1UseMarkWord: return NULL; 2766 default: ShouldNotReachHere(); 2767 } 2768 return NULL; // keep some compilers happy 2769 } 2770 2771 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) { 2772 switch (vo) { 2773 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj); 2774 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj); 2775 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked(); 2776 default: ShouldNotReachHere(); 2777 } 2778 return false; // keep some compilers happy 2779 } 2780 2781 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) { 2782 switch (vo) { 2783 case VerifyOption_G1UsePrevMarking: return "PTAMS"; 2784 case VerifyOption_G1UseNextMarking: return "NTAMS"; 2785 case VerifyOption_G1UseMarkWord: return "NONE"; 2786 default: ShouldNotReachHere(); 2787 } 2788 return NULL; // keep some compilers happy 2789 } 2790 2791 class VerifyRootsClosure: public OopClosure { 2792 private: 2793 G1CollectedHeap* _g1h; 2794 VerifyOption _vo; 2795 bool _failures; 2796 public: 2797 // _vo == UsePrevMarking -> use "prev" marking information, 2798 // _vo == UseNextMarking -> use "next" marking information, 2799 // _vo == UseMarkWord -> use mark word from object header. 2800 VerifyRootsClosure(VerifyOption vo) : 2801 _g1h(G1CollectedHeap::heap()), 2802 _vo(vo), 2803 _failures(false) { } 2804 2805 bool failures() { return _failures; } 2806 2807 template <class T> void do_oop_nv(T* p) { 2808 T heap_oop = oopDesc::load_heap_oop(p); 2809 if (!oopDesc::is_null(heap_oop)) { 2810 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 2811 if (_g1h->is_obj_dead_cond(obj, _vo)) { 2812 gclog_or_tty->print_cr("Root location " PTR_FORMAT " " 2813 "points to dead obj " PTR_FORMAT, p2i(p), p2i(obj)); 2814 if (_vo == VerifyOption_G1UseMarkWord) { 2815 gclog_or_tty->print_cr(" Mark word: " INTPTR_FORMAT, (intptr_t)obj->mark()); 2816 } 2817 obj->print_on(gclog_or_tty); 2818 _failures = true; 2819 } 2820 } 2821 } 2822 2823 void do_oop(oop* p) { do_oop_nv(p); } 2824 void do_oop(narrowOop* p) { do_oop_nv(p); } 2825 }; 2826 2827 class G1VerifyCodeRootOopClosure: public OopClosure { 2828 G1CollectedHeap* _g1h; 2829 OopClosure* _root_cl; 2830 nmethod* _nm; 2831 VerifyOption _vo; 2832 bool _failures; 2833 2834 template <class T> void do_oop_work(T* p) { 2835 // First verify that this root is live 2836 _root_cl->do_oop(p); 2837 2838 if (!G1VerifyHeapRegionCodeRoots) { 2839 // We're not verifying the code roots attached to heap region. 2840 return; 2841 } 2842 2843 // Don't check the code roots during marking verification in a full GC 2844 if (_vo == VerifyOption_G1UseMarkWord) { 2845 return; 2846 } 2847 2848 // Now verify that the current nmethod (which contains p) is 2849 // in the code root list of the heap region containing the 2850 // object referenced by p. 2851 2852 T heap_oop = oopDesc::load_heap_oop(p); 2853 if (!oopDesc::is_null(heap_oop)) { 2854 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 2855 2856 // Now fetch the region containing the object 2857 HeapRegion* hr = _g1h->heap_region_containing(obj); 2858 HeapRegionRemSet* hrrs = hr->rem_set(); 2859 // Verify that the strong code root list for this region 2860 // contains the nmethod 2861 if (!hrrs->strong_code_roots_list_contains(_nm)) { 2862 gclog_or_tty->print_cr("Code root location " PTR_FORMAT " " 2863 "from nmethod " PTR_FORMAT " not in strong " 2864 "code roots for region [" PTR_FORMAT "," PTR_FORMAT ")", 2865 p2i(p), p2i(_nm), p2i(hr->bottom()), p2i(hr->end())); 2866 _failures = true; 2867 } 2868 } 2869 } 2870 2871 public: 2872 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo): 2873 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {} 2874 2875 void do_oop(oop* p) { do_oop_work(p); } 2876 void do_oop(narrowOop* p) { do_oop_work(p); } 2877 2878 void set_nmethod(nmethod* nm) { _nm = nm; } 2879 bool failures() { return _failures; } 2880 }; 2881 2882 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure { 2883 G1VerifyCodeRootOopClosure* _oop_cl; 2884 2885 public: 2886 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl): 2887 _oop_cl(oop_cl) {} 2888 2889 void do_code_blob(CodeBlob* cb) { 2890 nmethod* nm = cb->as_nmethod_or_null(); 2891 if (nm != NULL) { 2892 _oop_cl->set_nmethod(nm); 2893 nm->oops_do(_oop_cl); 2894 } 2895 } 2896 }; 2897 2898 class YoungRefCounterClosure : public OopClosure { 2899 G1CollectedHeap* _g1h; 2900 int _count; 2901 public: 2902 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {} 2903 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } } 2904 void do_oop(narrowOop* p) { ShouldNotReachHere(); } 2905 2906 int count() { return _count; } 2907 void reset_count() { _count = 0; }; 2908 }; 2909 2910 class VerifyKlassClosure: public KlassClosure { 2911 YoungRefCounterClosure _young_ref_counter_closure; 2912 OopClosure *_oop_closure; 2913 public: 2914 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {} 2915 void do_klass(Klass* k) { 2916 k->oops_do(_oop_closure); 2917 2918 _young_ref_counter_closure.reset_count(); 2919 k->oops_do(&_young_ref_counter_closure); 2920 if (_young_ref_counter_closure.count() > 0) { 2921 guarantee(k->has_modified_oops(), "Klass " PTR_FORMAT ", has young refs but is not dirty.", p2i(k)); 2922 } 2923 } 2924 }; 2925 2926 class VerifyLivenessOopClosure: public OopClosure { 2927 G1CollectedHeap* _g1h; 2928 VerifyOption _vo; 2929 public: 2930 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo): 2931 _g1h(g1h), _vo(vo) 2932 { } 2933 void do_oop(narrowOop *p) { do_oop_work(p); } 2934 void do_oop( oop *p) { do_oop_work(p); } 2935 2936 template <class T> void do_oop_work(T *p) { 2937 oop obj = oopDesc::load_decode_heap_oop(p); 2938 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo), 2939 "Dead object referenced by a not dead object"); 2940 } 2941 }; 2942 2943 class VerifyObjsInRegionClosure: public ObjectClosure { 2944 private: 2945 G1CollectedHeap* _g1h; 2946 size_t _live_bytes; 2947 HeapRegion *_hr; 2948 VerifyOption _vo; 2949 public: 2950 // _vo == UsePrevMarking -> use "prev" marking information, 2951 // _vo == UseNextMarking -> use "next" marking information, 2952 // _vo == UseMarkWord -> use mark word from object header. 2953 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo) 2954 : _live_bytes(0), _hr(hr), _vo(vo) { 2955 _g1h = G1CollectedHeap::heap(); 2956 } 2957 void do_object(oop o) { 2958 VerifyLivenessOopClosure isLive(_g1h, _vo); 2959 assert(o != NULL, "Huh?"); 2960 if (!_g1h->is_obj_dead_cond(o, _vo)) { 2961 // If the object is alive according to the mark word, 2962 // then verify that the marking information agrees. 2963 // Note we can't verify the contra-positive of the 2964 // above: if the object is dead (according to the mark 2965 // word), it may not be marked, or may have been marked 2966 // but has since became dead, or may have been allocated 2967 // since the last marking. 2968 if (_vo == VerifyOption_G1UseMarkWord) { 2969 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch"); 2970 } 2971 2972 o->oop_iterate_no_header(&isLive); 2973 if (!_hr->obj_allocated_since_prev_marking(o)) { 2974 size_t obj_size = o->size(); // Make sure we don't overflow 2975 _live_bytes += (obj_size * HeapWordSize); 2976 } 2977 } 2978 } 2979 size_t live_bytes() { return _live_bytes; } 2980 }; 2981 2982 class VerifyArchiveOopClosure: public OopClosure { 2983 public: 2984 VerifyArchiveOopClosure(HeapRegion *hr) { } 2985 void do_oop(narrowOop *p) { do_oop_work(p); } 2986 void do_oop( oop *p) { do_oop_work(p); } 2987 2988 template <class T> void do_oop_work(T *p) { 2989 oop obj = oopDesc::load_decode_heap_oop(p); 2990 guarantee(obj == NULL || G1MarkSweep::in_archive_range(obj), 2991 "Archive object at " PTR_FORMAT " references a non-archive object at " PTR_FORMAT, 2992 p2i(p), p2i(obj)); 2993 } 2994 }; 2995 2996 class VerifyArchiveRegionClosure: public ObjectClosure { 2997 public: 2998 VerifyArchiveRegionClosure(HeapRegion *hr) { } 2999 // Verify that all object pointers are to archive regions. 3000 void do_object(oop o) { 3001 VerifyArchiveOopClosure checkOop(NULL); 3002 assert(o != NULL, "Should not be here for NULL oops"); 3003 o->oop_iterate_no_header(&checkOop); 3004 } 3005 }; 3006 3007 class VerifyRegionClosure: public HeapRegionClosure { 3008 private: 3009 bool _par; 3010 VerifyOption _vo; 3011 bool _failures; 3012 public: 3013 // _vo == UsePrevMarking -> use "prev" marking information, 3014 // _vo == UseNextMarking -> use "next" marking information, 3015 // _vo == UseMarkWord -> use mark word from object header. 3016 VerifyRegionClosure(bool par, VerifyOption vo) 3017 : _par(par), 3018 _vo(vo), 3019 _failures(false) {} 3020 3021 bool failures() { 3022 return _failures; 3023 } 3024 3025 bool doHeapRegion(HeapRegion* r) { 3026 // For archive regions, verify there are no heap pointers to 3027 // non-pinned regions. For all others, verify liveness info. 3028 if (r->is_archive()) { 3029 VerifyArchiveRegionClosure verify_oop_pointers(r); 3030 r->object_iterate(&verify_oop_pointers); 3031 return true; 3032 } 3033 if (!r->is_continues_humongous()) { 3034 bool failures = false; 3035 r->verify(_vo, &failures); 3036 if (failures) { 3037 _failures = true; 3038 } else if (!r->is_starts_humongous()) { 3039 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo); 3040 r->object_iterate(¬_dead_yet_cl); 3041 if (_vo != VerifyOption_G1UseNextMarking) { 3042 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) { 3043 gclog_or_tty->print_cr("[" PTR_FORMAT "," PTR_FORMAT "] " 3044 "max_live_bytes " SIZE_FORMAT " " 3045 "< calculated " SIZE_FORMAT, 3046 p2i(r->bottom()), p2i(r->end()), 3047 r->max_live_bytes(), 3048 not_dead_yet_cl.live_bytes()); 3049 _failures = true; 3050 } 3051 } else { 3052 // When vo == UseNextMarking we cannot currently do a sanity 3053 // check on the live bytes as the calculation has not been 3054 // finalized yet. 3055 } 3056 } 3057 } 3058 return false; // stop the region iteration if we hit a failure 3059 } 3060 }; 3061 3062 // This is the task used for parallel verification of the heap regions 3063 3064 class G1ParVerifyTask: public AbstractGangTask { 3065 private: 3066 G1CollectedHeap* _g1h; 3067 VerifyOption _vo; 3068 bool _failures; 3069 HeapRegionClaimer _hrclaimer; 3070 3071 public: 3072 // _vo == UsePrevMarking -> use "prev" marking information, 3073 // _vo == UseNextMarking -> use "next" marking information, 3074 // _vo == UseMarkWord -> use mark word from object header. 3075 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) : 3076 AbstractGangTask("Parallel verify task"), 3077 _g1h(g1h), 3078 _vo(vo), 3079 _failures(false), 3080 _hrclaimer(g1h->workers()->active_workers()) {} 3081 3082 bool failures() { 3083 return _failures; 3084 } 3085 3086 void work(uint worker_id) { 3087 HandleMark hm; 3088 VerifyRegionClosure blk(true, _vo); 3089 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer); 3090 if (blk.failures()) { 3091 _failures = true; 3092 } 3093 } 3094 }; 3095 3096 void G1CollectedHeap::verify(bool silent, VerifyOption vo) { 3097 if (SafepointSynchronize::is_at_safepoint()) { 3098 assert(Thread::current()->is_VM_thread(), 3099 "Expected to be executed serially by the VM thread at this point"); 3100 3101 if (!silent) { gclog_or_tty->print("Roots "); } 3102 VerifyRootsClosure rootsCl(vo); 3103 VerifyKlassClosure klassCl(this, &rootsCl); 3104 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false); 3105 3106 // We apply the relevant closures to all the oops in the 3107 // system dictionary, class loader data graph, the string table 3108 // and the nmethods in the code cache. 3109 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo); 3110 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl); 3111 3112 { 3113 G1RootProcessor root_processor(this, 1); 3114 root_processor.process_all_roots(&rootsCl, 3115 &cldCl, 3116 &blobsCl); 3117 } 3118 3119 bool failures = rootsCl.failures() || codeRootsCl.failures(); 3120 3121 if (vo != VerifyOption_G1UseMarkWord) { 3122 // If we're verifying during a full GC then the region sets 3123 // will have been torn down at the start of the GC. Therefore 3124 // verifying the region sets will fail. So we only verify 3125 // the region sets when not in a full GC. 3126 if (!silent) { gclog_or_tty->print("HeapRegionSets "); } 3127 verify_region_sets(); 3128 } 3129 3130 if (!silent) { gclog_or_tty->print("HeapRegions "); } 3131 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) { 3132 3133 G1ParVerifyTask task(this, vo); 3134 workers()->run_task(&task); 3135 if (task.failures()) { 3136 failures = true; 3137 } 3138 3139 } else { 3140 VerifyRegionClosure blk(false, vo); 3141 heap_region_iterate(&blk); 3142 if (blk.failures()) { 3143 failures = true; 3144 } 3145 } 3146 3147 if (G1StringDedup::is_enabled()) { 3148 if (!silent) gclog_or_tty->print("StrDedup "); 3149 G1StringDedup::verify(); 3150 } 3151 3152 if (failures) { 3153 gclog_or_tty->print_cr("Heap:"); 3154 // It helps to have the per-region information in the output to 3155 // help us track down what went wrong. This is why we call 3156 // print_extended_on() instead of print_on(). 3157 print_extended_on(gclog_or_tty); 3158 gclog_or_tty->cr(); 3159 gclog_or_tty->flush(); 3160 } 3161 guarantee(!failures, "there should not have been any failures"); 3162 } else { 3163 if (!silent) { 3164 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet"); 3165 if (G1StringDedup::is_enabled()) { 3166 gclog_or_tty->print(", StrDedup"); 3167 } 3168 gclog_or_tty->print(") "); 3169 } 3170 } 3171 } 3172 3173 void G1CollectedHeap::verify(bool silent) { 3174 verify(silent, VerifyOption_G1UsePrevMarking); 3175 } 3176 3177 double G1CollectedHeap::verify(bool guard, const char* msg) { 3178 double verify_time_ms = 0.0; 3179 3180 if (guard && total_collections() >= VerifyGCStartAt) { 3181 double verify_start = os::elapsedTime(); 3182 HandleMark hm; // Discard invalid handles created during verification 3183 prepare_for_verify(); 3184 Universe::verify(VerifyOption_G1UsePrevMarking, msg); 3185 verify_time_ms = (os::elapsedTime() - verify_start) * 1000; 3186 } 3187 3188 return verify_time_ms; 3189 } 3190 3191 void G1CollectedHeap::verify_before_gc() { 3192 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:"); 3193 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms); 3194 } 3195 3196 void G1CollectedHeap::verify_after_gc() { 3197 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:"); 3198 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms); 3199 } 3200 3201 class PrintRegionClosure: public HeapRegionClosure { 3202 outputStream* _st; 3203 public: 3204 PrintRegionClosure(outputStream* st) : _st(st) {} 3205 bool doHeapRegion(HeapRegion* r) { 3206 r->print_on(_st); 3207 return false; 3208 } 3209 }; 3210 3211 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 3212 const HeapRegion* hr, 3213 const VerifyOption vo) const { 3214 switch (vo) { 3215 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); 3216 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); 3217 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked() && !hr->is_archive(); 3218 default: ShouldNotReachHere(); 3219 } 3220 return false; // keep some compilers happy 3221 } 3222 3223 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 3224 const VerifyOption vo) const { 3225 switch (vo) { 3226 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); 3227 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); 3228 case VerifyOption_G1UseMarkWord: { 3229 HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj); 3230 return !obj->is_gc_marked() && !hr->is_archive(); 3231 } 3232 default: ShouldNotReachHere(); 3233 } 3234 return false; // keep some compilers happy 3235 } 3236 3237 void G1CollectedHeap::print_on(outputStream* st) const { 3238 st->print(" %-20s", "garbage-first heap"); 3239 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 3240 capacity()/K, used_unlocked()/K); 3241 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")", 3242 p2i(_hrm.reserved().start()), 3243 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords), 3244 p2i(_hrm.reserved().end())); 3245 st->cr(); 3246 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); 3247 uint young_regions = _young_list->length(); 3248 st->print("%u young (" SIZE_FORMAT "K), ", young_regions, 3249 (size_t) young_regions * HeapRegion::GrainBytes / K); 3250 uint survivor_regions = g1_policy()->recorded_survivor_regions(); 3251 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, 3252 (size_t) survivor_regions * HeapRegion::GrainBytes / K); 3253 st->cr(); 3254 MetaspaceAux::print_on(st); 3255 } 3256 3257 void G1CollectedHeap::print_extended_on(outputStream* st) const { 3258 print_on(st); 3259 3260 // Print the per-region information. 3261 st->cr(); 3262 st->print_cr("Heap Regions: (E=young(eden), S=young(survivor), O=old, " 3263 "HS=humongous(starts), HC=humongous(continues), " 3264 "CS=collection set, F=free, A=archive, TS=gc time stamp, " 3265 "PTAMS=previous top-at-mark-start, " 3266 "NTAMS=next top-at-mark-start)"); 3267 PrintRegionClosure blk(st); 3268 heap_region_iterate(&blk); 3269 } 3270 3271 void G1CollectedHeap::print_on_error(outputStream* st) const { 3272 this->CollectedHeap::print_on_error(st); 3273 3274 if (_cm != NULL) { 3275 st->cr(); 3276 _cm->print_on_error(st); 3277 } 3278 } 3279 3280 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const { 3281 workers()->print_worker_threads_on(st); 3282 _cmThread->print_on(st); 3283 st->cr(); 3284 _cm->print_worker_threads_on(st); 3285 _cg1r->print_worker_threads_on(st); 3286 if (G1StringDedup::is_enabled()) { 3287 G1StringDedup::print_worker_threads_on(st); 3288 } 3289 } 3290 3291 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { 3292 workers()->threads_do(tc); 3293 tc->do_thread(_cmThread); 3294 _cg1r->threads_do(tc); 3295 if (G1StringDedup::is_enabled()) { 3296 G1StringDedup::threads_do(tc); 3297 } 3298 } 3299 3300 void G1CollectedHeap::print_tracing_info() const { 3301 // We'll overload this to mean "trace GC pause statistics." 3302 if (TraceYoungGenTime || TraceOldGenTime) { 3303 // The "G1CollectorPolicy" is keeping track of these stats, so delegate 3304 // to that. 3305 g1_policy()->print_tracing_info(); 3306 } 3307 if (G1SummarizeRSetStats) { 3308 g1_rem_set()->print_summary_info(); 3309 } 3310 if (G1SummarizeConcMark) { 3311 concurrent_mark()->print_summary_info(); 3312 } 3313 g1_policy()->print_yg_surv_rate_info(); 3314 } 3315 3316 #ifndef PRODUCT 3317 // Helpful for debugging RSet issues. 3318 3319 class PrintRSetsClosure : public HeapRegionClosure { 3320 private: 3321 const char* _msg; 3322 size_t _occupied_sum; 3323 3324 public: 3325 bool doHeapRegion(HeapRegion* r) { 3326 HeapRegionRemSet* hrrs = r->rem_set(); 3327 size_t occupied = hrrs->occupied(); 3328 _occupied_sum += occupied; 3329 3330 gclog_or_tty->print_cr("Printing RSet for region " HR_FORMAT, 3331 HR_FORMAT_PARAMS(r)); 3332 if (occupied == 0) { 3333 gclog_or_tty->print_cr(" RSet is empty"); 3334 } else { 3335 hrrs->print(); 3336 } 3337 gclog_or_tty->print_cr("----------"); 3338 return false; 3339 } 3340 3341 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { 3342 gclog_or_tty->cr(); 3343 gclog_or_tty->print_cr("========================================"); 3344 gclog_or_tty->print_cr("%s", msg); 3345 gclog_or_tty->cr(); 3346 } 3347 3348 ~PrintRSetsClosure() { 3349 gclog_or_tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum); 3350 gclog_or_tty->print_cr("========================================"); 3351 gclog_or_tty->cr(); 3352 } 3353 }; 3354 3355 void G1CollectedHeap::print_cset_rsets() { 3356 PrintRSetsClosure cl("Printing CSet RSets"); 3357 collection_set_iterate(&cl); 3358 } 3359 3360 void G1CollectedHeap::print_all_rsets() { 3361 PrintRSetsClosure cl("Printing All RSets");; 3362 heap_region_iterate(&cl); 3363 } 3364 #endif // PRODUCT 3365 3366 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() { 3367 YoungList* young_list = heap()->young_list(); 3368 3369 size_t eden_used_bytes = young_list->eden_used_bytes(); 3370 size_t survivor_used_bytes = young_list->survivor_used_bytes(); 3371 3372 size_t eden_capacity_bytes = 3373 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes; 3374 3375 VirtualSpaceSummary heap_summary = create_heap_space_summary(); 3376 return G1HeapSummary(heap_summary, used(), eden_used_bytes, eden_capacity_bytes, survivor_used_bytes); 3377 } 3378 3379 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) { 3380 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(), 3381 stats->unused(), stats->used(), stats->region_end_waste(), 3382 stats->regions_filled(), stats->direct_allocated(), 3383 stats->failure_used(), stats->failure_waste()); 3384 } 3385 3386 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) { 3387 const G1HeapSummary& heap_summary = create_g1_heap_summary(); 3388 gc_tracer->report_gc_heap_summary(when, heap_summary); 3389 3390 const MetaspaceSummary& metaspace_summary = create_metaspace_summary(); 3391 gc_tracer->report_metaspace_summary(when, metaspace_summary); 3392 } 3393 3394 3395 G1CollectedHeap* G1CollectedHeap::heap() { 3396 CollectedHeap* heap = Universe::heap(); 3397 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()"); 3398 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap"); 3399 return (G1CollectedHeap*)heap; 3400 } 3401 3402 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) { 3403 // always_do_update_barrier = false; 3404 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 3405 // Fill TLAB's and such 3406 accumulate_statistics_all_tlabs(); 3407 ensure_parsability(true); 3408 3409 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) && 3410 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) { 3411 g1_rem_set()->print_periodic_summary_info("Before GC RS summary"); 3412 } 3413 } 3414 3415 void G1CollectedHeap::gc_epilogue(bool full) { 3416 3417 if (G1SummarizeRSetStats && 3418 (G1SummarizeRSetStatsPeriod > 0) && 3419 // we are at the end of the GC. Total collections has already been increased. 3420 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) { 3421 g1_rem_set()->print_periodic_summary_info("After GC RS summary"); 3422 } 3423 3424 // FIXME: what is this about? 3425 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" 3426 // is set. 3427 #if defined(COMPILER2) || INCLUDE_JVMCI 3428 assert(DerivedPointerTable::is_empty(), "derived pointer present"); 3429 #endif 3430 // always_do_update_barrier = true; 3431 3432 resize_all_tlabs(); 3433 allocation_context_stats().update(full); 3434 3435 // We have just completed a GC. Update the soft reference 3436 // policy with the new heap occupancy 3437 Universe::update_heap_info_at_gc(); 3438 } 3439 3440 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, 3441 uint gc_count_before, 3442 bool* succeeded, 3443 GCCause::Cause gc_cause) { 3444 assert_heap_not_locked_and_not_at_safepoint(); 3445 g1_policy()->record_stop_world_start(); 3446 VM_G1IncCollectionPause op(gc_count_before, 3447 word_size, 3448 false, /* should_initiate_conc_mark */ 3449 g1_policy()->max_pause_time_ms(), 3450 gc_cause); 3451 3452 op.set_allocation_context(AllocationContext::current()); 3453 VMThread::execute(&op); 3454 3455 HeapWord* result = op.result(); 3456 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded(); 3457 assert(result == NULL || ret_succeeded, 3458 "the result should be NULL if the VM did not succeed"); 3459 *succeeded = ret_succeeded; 3460 3461 assert_heap_not_locked(); 3462 return result; 3463 } 3464 3465 void 3466 G1CollectedHeap::doConcurrentMark() { 3467 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); 3468 if (!_cmThread->in_progress()) { 3469 _cmThread->set_started(); 3470 CGC_lock->notify(); 3471 } 3472 } 3473 3474 size_t G1CollectedHeap::pending_card_num() { 3475 size_t extra_cards = 0; 3476 JavaThread *curr = Threads::first(); 3477 while (curr != NULL) { 3478 DirtyCardQueue& dcq = curr->dirty_card_queue(); 3479 extra_cards += dcq.size(); 3480 curr = curr->next(); 3481 } 3482 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 3483 size_t buffer_size = dcqs.buffer_size(); 3484 size_t buffer_num = dcqs.completed_buffers_num(); 3485 3486 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes 3487 // in bytes - not the number of 'entries'. We need to convert 3488 // into a number of cards. 3489 return (buffer_size * buffer_num + extra_cards) / oopSize; 3490 } 3491 3492 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure { 3493 private: 3494 size_t _total_humongous; 3495 size_t _candidate_humongous; 3496 3497 DirtyCardQueue _dcq; 3498 3499 // We don't nominate objects with many remembered set entries, on 3500 // the assumption that such objects are likely still live. 3501 bool is_remset_small(HeapRegion* region) const { 3502 HeapRegionRemSet* const rset = region->rem_set(); 3503 return G1EagerReclaimHumongousObjectsWithStaleRefs 3504 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) 3505 : rset->is_empty(); 3506 } 3507 3508 bool is_typeArray_region(HeapRegion* region) const { 3509 return oop(region->bottom())->is_typeArray(); 3510 } 3511 3512 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const { 3513 assert(region->is_starts_humongous(), "Must start a humongous object"); 3514 3515 // Candidate selection must satisfy the following constraints 3516 // while concurrent marking is in progress: 3517 // 3518 // * In order to maintain SATB invariants, an object must not be 3519 // reclaimed if it was allocated before the start of marking and 3520 // has not had its references scanned. Such an object must have 3521 // its references (including type metadata) scanned to ensure no 3522 // live objects are missed by the marking process. Objects 3523 // allocated after the start of concurrent marking don't need to 3524 // be scanned. 3525 // 3526 // * An object must not be reclaimed if it is on the concurrent 3527 // mark stack. Objects allocated after the start of concurrent 3528 // marking are never pushed on the mark stack. 3529 // 3530 // Nominating only objects allocated after the start of concurrent 3531 // marking is sufficient to meet both constraints. This may miss 3532 // some objects that satisfy the constraints, but the marking data 3533 // structures don't support efficiently performing the needed 3534 // additional tests or scrubbing of the mark stack. 3535 // 3536 // However, we presently only nominate is_typeArray() objects. 3537 // A humongous object containing references induces remembered 3538 // set entries on other regions. In order to reclaim such an 3539 // object, those remembered sets would need to be cleaned up. 3540 // 3541 // We also treat is_typeArray() objects specially, allowing them 3542 // to be reclaimed even if allocated before the start of 3543 // concurrent mark. For this we rely on mark stack insertion to 3544 // exclude is_typeArray() objects, preventing reclaiming an object 3545 // that is in the mark stack. We also rely on the metadata for 3546 // such objects to be built-in and so ensured to be kept live. 3547 // Frequent allocation and drop of large binary blobs is an 3548 // important use case for eager reclaim, and this special handling 3549 // may reduce needed headroom. 3550 3551 return is_typeArray_region(region) && is_remset_small(region); 3552 } 3553 3554 public: 3555 RegisterHumongousWithInCSetFastTestClosure() 3556 : _total_humongous(0), 3557 _candidate_humongous(0), 3558 _dcq(&JavaThread::dirty_card_queue_set()) { 3559 } 3560 3561 virtual bool doHeapRegion(HeapRegion* r) { 3562 if (!r->is_starts_humongous()) { 3563 return false; 3564 } 3565 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 3566 3567 bool is_candidate = humongous_region_is_candidate(g1h, r); 3568 uint rindex = r->hrm_index(); 3569 g1h->set_humongous_reclaim_candidate(rindex, is_candidate); 3570 if (is_candidate) { 3571 _candidate_humongous++; 3572 g1h->register_humongous_region_with_cset(rindex); 3573 // Is_candidate already filters out humongous object with large remembered sets. 3574 // If we have a humongous object with a few remembered sets, we simply flush these 3575 // remembered set entries into the DCQS. That will result in automatic 3576 // re-evaluation of their remembered set entries during the following evacuation 3577 // phase. 3578 if (!r->rem_set()->is_empty()) { 3579 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries), 3580 "Found a not-small remembered set here. This is inconsistent with previous assumptions."); 3581 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set(); 3582 HeapRegionRemSetIterator hrrs(r->rem_set()); 3583 size_t card_index; 3584 while (hrrs.has_next(card_index)) { 3585 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index); 3586 // The remembered set might contain references to already freed 3587 // regions. Filter out such entries to avoid failing card table 3588 // verification. 3589 if (!g1h->heap_region_containing(bs->addr_for(card_ptr))->is_free()) { 3590 if (*card_ptr != CardTableModRefBS::dirty_card_val()) { 3591 *card_ptr = CardTableModRefBS::dirty_card_val(); 3592 _dcq.enqueue(card_ptr); 3593 } 3594 } 3595 } 3596 r->rem_set()->clear_locked(); 3597 } 3598 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty."); 3599 } 3600 _total_humongous++; 3601 3602 return false; 3603 } 3604 3605 size_t total_humongous() const { return _total_humongous; } 3606 size_t candidate_humongous() const { return _candidate_humongous; } 3607 3608 void flush_rem_set_entries() { _dcq.flush(); } 3609 }; 3610 3611 void G1CollectedHeap::register_humongous_regions_with_cset() { 3612 if (!G1EagerReclaimHumongousObjects) { 3613 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0); 3614 return; 3615 } 3616 double time = os::elapsed_counter(); 3617 3618 // Collect reclaim candidate information and register candidates with cset. 3619 RegisterHumongousWithInCSetFastTestClosure cl; 3620 heap_region_iterate(&cl); 3621 3622 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0; 3623 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time, 3624 cl.total_humongous(), 3625 cl.candidate_humongous()); 3626 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0; 3627 3628 // Finally flush all remembered set entries to re-check into the global DCQS. 3629 cl.flush_rem_set_entries(); 3630 } 3631 3632 #ifdef ASSERT 3633 class VerifyCSetClosure: public HeapRegionClosure { 3634 public: 3635 bool doHeapRegion(HeapRegion* hr) { 3636 // Here we check that the CSet region's RSet is ready for parallel 3637 // iteration. The fields that we'll verify are only manipulated 3638 // when the region is part of a CSet and is collected. Afterwards, 3639 // we reset these fields when we clear the region's RSet (when the 3640 // region is freed) so they are ready when the region is 3641 // re-allocated. The only exception to this is if there's an 3642 // evacuation failure and instead of freeing the region we leave 3643 // it in the heap. In that case, we reset these fields during 3644 // evacuation failure handling. 3645 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification"); 3646 3647 // Here's a good place to add any other checks we'd like to 3648 // perform on CSet regions. 3649 return false; 3650 } 3651 }; 3652 #endif // ASSERT 3653 3654 uint G1CollectedHeap::num_task_queues() const { 3655 return _task_queues->size(); 3656 } 3657 3658 #if TASKQUEUE_STATS 3659 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) { 3660 st->print_raw_cr("GC Task Stats"); 3661 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); 3662 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); 3663 } 3664 3665 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const { 3666 print_taskqueue_stats_hdr(st); 3667 3668 TaskQueueStats totals; 3669 const uint n = num_task_queues(); 3670 for (uint i = 0; i < n; ++i) { 3671 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr(); 3672 totals += task_queue(i)->stats; 3673 } 3674 st->print_raw("tot "); totals.print(st); st->cr(); 3675 3676 DEBUG_ONLY(totals.verify()); 3677 } 3678 3679 void G1CollectedHeap::reset_taskqueue_stats() { 3680 const uint n = num_task_queues(); 3681 for (uint i = 0; i < n; ++i) { 3682 task_queue(i)->stats.reset(); 3683 } 3684 } 3685 #endif // TASKQUEUE_STATS 3686 3687 void G1CollectedHeap::log_gc_header() { 3688 if (!G1Log::fine()) { 3689 return; 3690 } 3691 3692 gclog_or_tty->gclog_stamp(); 3693 3694 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause()) 3695 .append(collector_state()->gcs_are_young() ? "(young)" : "(mixed)") 3696 .append(collector_state()->during_initial_mark_pause() ? " (initial-mark)" : ""); 3697 3698 gclog_or_tty->print("[%s", (const char*)gc_cause_str); 3699 } 3700 3701 void G1CollectedHeap::log_gc_footer(double pause_time_sec) { 3702 if (!G1Log::fine()) { 3703 return; 3704 } 3705 3706 if (G1Log::finer()) { 3707 if (evacuation_failed()) { 3708 gclog_or_tty->print(" (to-space exhausted)"); 3709 } 3710 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec); 3711 g1_policy()->print_phases(pause_time_sec); 3712 g1_policy()->print_detailed_heap_transition(); 3713 } else { 3714 if (evacuation_failed()) { 3715 gclog_or_tty->print("--"); 3716 } 3717 g1_policy()->print_heap_transition(); 3718 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec); 3719 } 3720 gclog_or_tty->flush(); 3721 } 3722 3723 void G1CollectedHeap::wait_for_root_region_scanning() { 3724 double scan_wait_start = os::elapsedTime(); 3725 // We have to wait until the CM threads finish scanning the 3726 // root regions as it's the only way to ensure that all the 3727 // objects on them have been correctly scanned before we start 3728 // moving them during the GC. 3729 bool waited = _cm->root_regions()->wait_until_scan_finished(); 3730 double wait_time_ms = 0.0; 3731 if (waited) { 3732 double scan_wait_end = os::elapsedTime(); 3733 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0; 3734 } 3735 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms); 3736 } 3737 3738 bool 3739 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { 3740 assert_at_safepoint(true /* should_be_vm_thread */); 3741 guarantee(!is_gc_active(), "collection is not reentrant"); 3742 3743 if (GC_locker::check_active_before_gc()) { 3744 return false; 3745 } 3746 3747 _gc_timer_stw->register_gc_start(); 3748 3749 GCIdMark gc_id_mark; 3750 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start()); 3751 3752 SvcGCMarker sgcm(SvcGCMarker::MINOR); 3753 ResourceMark rm; 3754 3755 wait_for_root_region_scanning(); 3756 3757 G1Log::update_level(); 3758 print_heap_before_gc(); 3759 trace_heap_before_gc(_gc_tracer_stw); 3760 3761 verify_region_sets_optional(); 3762 verify_dirty_young_regions(); 3763 3764 // This call will decide whether this pause is an initial-mark 3765 // pause. If it is, during_initial_mark_pause() will return true 3766 // for the duration of this pause. 3767 g1_policy()->decide_on_conc_mark_initiation(); 3768 3769 // We do not allow initial-mark to be piggy-backed on a mixed GC. 3770 assert(!collector_state()->during_initial_mark_pause() || 3771 collector_state()->gcs_are_young(), "sanity"); 3772 3773 // We also do not allow mixed GCs during marking. 3774 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity"); 3775 3776 // Record whether this pause is an initial mark. When the current 3777 // thread has completed its logging output and it's safe to signal 3778 // the CM thread, the flag's value in the policy has been reset. 3779 bool should_start_conc_mark = collector_state()->during_initial_mark_pause(); 3780 3781 // Inner scope for scope based logging, timers, and stats collection 3782 { 3783 EvacuationInfo evacuation_info; 3784 3785 if (collector_state()->during_initial_mark_pause()) { 3786 // We are about to start a marking cycle, so we increment the 3787 // full collection counter. 3788 increment_old_marking_cycles_started(); 3789 register_concurrent_cycle_start(_gc_timer_stw->gc_start()); 3790 } 3791 3792 _gc_tracer_stw->report_yc_type(collector_state()->yc_type()); 3793 3794 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty); 3795 3796 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 3797 workers()->active_workers(), 3798 Threads::number_of_non_daemon_threads()); 3799 workers()->set_active_workers(active_workers); 3800 3801 double pause_start_sec = os::elapsedTime(); 3802 g1_policy()->note_gc_start(active_workers); 3803 log_gc_header(); 3804 3805 TraceCollectorStats tcs(g1mm()->incremental_collection_counters()); 3806 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause()); 3807 3808 // If the secondary_free_list is not empty, append it to the 3809 // free_list. No need to wait for the cleanup operation to finish; 3810 // the region allocation code will check the secondary_free_list 3811 // and wait if necessary. If the G1StressConcRegionFreeing flag is 3812 // set, skip this step so that the region allocation code has to 3813 // get entries from the secondary_free_list. 3814 if (!G1StressConcRegionFreeing) { 3815 append_secondary_free_list_if_not_empty_with_lock(); 3816 } 3817 3818 assert(check_young_list_well_formed(), "young list should be well formed"); 3819 3820 // Don't dynamically change the number of GC threads this early. A value of 3821 // 0 is used to indicate serial work. When parallel work is done, 3822 // it will be set. 3823 3824 { // Call to jvmpi::post_class_unload_events must occur outside of active GC 3825 IsGCActiveMark x; 3826 3827 gc_prologue(false); 3828 increment_total_collections(false /* full gc */); 3829 increment_gc_time_stamp(); 3830 3831 verify_before_gc(); 3832 3833 check_bitmaps("GC Start"); 3834 3835 #if defined(COMPILER2) || INCLUDE_JVMCI 3836 DerivedPointerTable::clear(); 3837 #endif 3838 3839 // Please see comment in g1CollectedHeap.hpp and 3840 // G1CollectedHeap::ref_processing_init() to see how 3841 // reference processing currently works in G1. 3842 3843 // Enable discovery in the STW reference processor 3844 ref_processor_stw()->enable_discovery(); 3845 3846 { 3847 // We want to temporarily turn off discovery by the 3848 // CM ref processor, if necessary, and turn it back on 3849 // on again later if we do. Using a scoped 3850 // NoRefDiscovery object will do this. 3851 NoRefDiscovery no_cm_discovery(ref_processor_cm()); 3852 3853 // Forget the current alloc region (we might even choose it to be part 3854 // of the collection set!). 3855 _allocator->release_mutator_alloc_region(); 3856 3857 // We should call this after we retire the mutator alloc 3858 // region(s) so that all the ALLOC / RETIRE events are generated 3859 // before the start GC event. 3860 _hr_printer.start_gc(false /* full */, (size_t) total_collections()); 3861 3862 // This timing is only used by the ergonomics to handle our pause target. 3863 // It is unclear why this should not include the full pause. We will 3864 // investigate this in CR 7178365. 3865 // 3866 // Preserving the old comment here if that helps the investigation: 3867 // 3868 // The elapsed time induced by the start time below deliberately elides 3869 // the possible verification above. 3870 double sample_start_time_sec = os::elapsedTime(); 3871 3872 g1_policy()->record_collection_pause_start(sample_start_time_sec); 3873 3874 if (collector_state()->during_initial_mark_pause()) { 3875 concurrent_mark()->checkpointRootsInitialPre(); 3876 } 3877 3878 double time_remaining_ms = g1_policy()->finalize_young_cset_part(target_pause_time_ms); 3879 g1_policy()->finalize_old_cset_part(time_remaining_ms); 3880 3881 evacuation_info.set_collectionset_regions(g1_policy()->cset_region_length()); 3882 3883 register_humongous_regions_with_cset(); 3884 3885 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table."); 3886 3887 _cm->note_start_of_gc(); 3888 // We call this after finalize_cset() to 3889 // ensure that the CSet has been finalized. 3890 _cm->verify_no_cset_oops(); 3891 3892 if (_hr_printer.is_active()) { 3893 HeapRegion* hr = g1_policy()->collection_set(); 3894 while (hr != NULL) { 3895 _hr_printer.cset(hr); 3896 hr = hr->next_in_collection_set(); 3897 } 3898 } 3899 3900 #ifdef ASSERT 3901 VerifyCSetClosure cl; 3902 collection_set_iterate(&cl); 3903 #endif // ASSERT 3904 3905 // Initialize the GC alloc regions. 3906 _allocator->init_gc_alloc_regions(evacuation_info); 3907 3908 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), g1_policy()->young_cset_region_length()); 3909 pre_evacuate_collection_set(); 3910 3911 // Actually do the work... 3912 evacuate_collection_set(evacuation_info, &per_thread_states); 3913 3914 post_evacuate_collection_set(evacuation_info, &per_thread_states); 3915 3916 const size_t* surviving_young_words = per_thread_states.surviving_young_words(); 3917 free_collection_set(g1_policy()->collection_set(), evacuation_info, surviving_young_words); 3918 3919 eagerly_reclaim_humongous_regions(); 3920 3921 g1_policy()->clear_collection_set(); 3922 3923 // Start a new incremental collection set for the next pause. 3924 g1_policy()->start_incremental_cset_building(); 3925 3926 clear_cset_fast_test(); 3927 3928 _young_list->reset_sampled_info(); 3929 3930 // Don't check the whole heap at this point as the 3931 // GC alloc regions from this pause have been tagged 3932 // as survivors and moved on to the survivor list. 3933 // Survivor regions will fail the !is_young() check. 3934 assert(check_young_list_empty(false /* check_heap */), 3935 "young list should be empty"); 3936 3937 g1_policy()->record_survivor_regions(_young_list->survivor_length(), 3938 _young_list->first_survivor_region(), 3939 _young_list->last_survivor_region()); 3940 3941 _young_list->reset_auxilary_lists(); 3942 3943 if (evacuation_failed()) { 3944 set_used(recalculate_used()); 3945 if (_archive_allocator != NULL) { 3946 _archive_allocator->clear_used(); 3947 } 3948 for (uint i = 0; i < ParallelGCThreads; i++) { 3949 if (_evacuation_failed_info_array[i].has_failed()) { 3950 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]); 3951 } 3952 } 3953 } else { 3954 // The "used" of the the collection set have already been subtracted 3955 // when they were freed. Add in the bytes evacuated. 3956 increase_used(g1_policy()->bytes_copied_during_gc()); 3957 } 3958 3959 if (collector_state()->during_initial_mark_pause()) { 3960 // We have to do this before we notify the CM threads that 3961 // they can start working to make sure that all the 3962 // appropriate initialization is done on the CM object. 3963 concurrent_mark()->checkpointRootsInitialPost(); 3964 collector_state()->set_mark_in_progress(true); 3965 // Note that we don't actually trigger the CM thread at 3966 // this point. We do that later when we're sure that 3967 // the current thread has completed its logging output. 3968 } 3969 3970 allocate_dummy_regions(); 3971 3972 _allocator->init_mutator_alloc_region(); 3973 3974 { 3975 size_t expand_bytes = g1_policy()->expansion_amount(); 3976 if (expand_bytes > 0) { 3977 size_t bytes_before = capacity(); 3978 // No need for an ergo verbose message here, 3979 // expansion_amount() does this when it returns a value > 0. 3980 double expand_ms; 3981 if (!expand(expand_bytes, &expand_ms)) { 3982 // We failed to expand the heap. Cannot do anything about it. 3983 } 3984 g1_policy()->phase_times()->record_expand_heap_time(expand_ms); 3985 } 3986 } 3987 3988 // We redo the verification but now wrt to the new CSet which 3989 // has just got initialized after the previous CSet was freed. 3990 _cm->verify_no_cset_oops(); 3991 _cm->note_end_of_gc(); 3992 3993 // This timing is only used by the ergonomics to handle our pause target. 3994 // It is unclear why this should not include the full pause. We will 3995 // investigate this in CR 7178365. 3996 double sample_end_time_sec = os::elapsedTime(); 3997 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; 3998 size_t total_cards_scanned = per_thread_states.total_cards_scanned(); 3999 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned); 4000 4001 evacuation_info.set_collectionset_used_before(g1_policy()->collection_set_bytes_used_before()); 4002 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc()); 4003 4004 MemoryService::track_memory_usage(); 4005 4006 // In prepare_for_verify() below we'll need to scan the deferred 4007 // update buffers to bring the RSets up-to-date if 4008 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning 4009 // the update buffers we'll probably need to scan cards on the 4010 // regions we just allocated to (i.e., the GC alloc 4011 // regions). However, during the last GC we called 4012 // set_saved_mark() on all the GC alloc regions, so card 4013 // scanning might skip the [saved_mark_word()...top()] area of 4014 // those regions (i.e., the area we allocated objects into 4015 // during the last GC). But it shouldn't. Given that 4016 // saved_mark_word() is conditional on whether the GC time stamp 4017 // on the region is current or not, by incrementing the GC time 4018 // stamp here we invalidate all the GC time stamps on all the 4019 // regions and saved_mark_word() will simply return top() for 4020 // all the regions. This is a nicer way of ensuring this rather 4021 // than iterating over the regions and fixing them. In fact, the 4022 // GC time stamp increment here also ensures that 4023 // saved_mark_word() will return top() between pauses, i.e., 4024 // during concurrent refinement. So we don't need the 4025 // is_gc_active() check to decided which top to use when 4026 // scanning cards (see CR 7039627). 4027 increment_gc_time_stamp(); 4028 4029 verify_after_gc(); 4030 check_bitmaps("GC End"); 4031 4032 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 4033 ref_processor_stw()->verify_no_references_recorded(); 4034 4035 // CM reference discovery will be re-enabled if necessary. 4036 } 4037 4038 // We should do this after we potentially expand the heap so 4039 // that all the COMMIT events are generated before the end GC 4040 // event, and after we retire the GC alloc regions so that all 4041 // RETIRE events are generated before the end GC event. 4042 _hr_printer.end_gc(false /* full */, (size_t) total_collections()); 4043 4044 #ifdef TRACESPINNING 4045 ParallelTaskTerminator::print_termination_counts(); 4046 #endif 4047 4048 gc_epilogue(false); 4049 } 4050 4051 // Print the remainder of the GC log output. 4052 log_gc_footer(os::elapsedTime() - pause_start_sec); 4053 4054 // It is not yet to safe to tell the concurrent mark to 4055 // start as we have some optional output below. We don't want the 4056 // output from the concurrent mark thread interfering with this 4057 // logging output either. 4058 4059 _hrm.verify_optional(); 4060 verify_region_sets_optional(); 4061 4062 TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats()); 4063 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); 4064 4065 print_heap_after_gc(); 4066 trace_heap_after_gc(_gc_tracer_stw); 4067 4068 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 4069 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 4070 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 4071 // before any GC notifications are raised. 4072 g1mm()->update_sizes(); 4073 4074 _gc_tracer_stw->report_evacuation_info(&evacuation_info); 4075 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold()); 4076 _gc_timer_stw->register_gc_end(); 4077 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions()); 4078 } 4079 // It should now be safe to tell the concurrent mark thread to start 4080 // without its logging output interfering with the logging output 4081 // that came from the pause. 4082 4083 if (should_start_conc_mark) { 4084 // CAUTION: after the doConcurrentMark() call below, 4085 // the concurrent marking thread(s) could be running 4086 // concurrently with us. Make sure that anything after 4087 // this point does not assume that we are the only GC thread 4088 // running. Note: of course, the actual marking work will 4089 // not start until the safepoint itself is released in 4090 // SuspendibleThreadSet::desynchronize(). 4091 doConcurrentMark(); 4092 } 4093 4094 return true; 4095 } 4096 4097 void G1CollectedHeap::remove_self_forwarding_pointers() { 4098 double remove_self_forwards_start = os::elapsedTime(); 4099 4100 G1ParRemoveSelfForwardPtrsTask rsfp_task; 4101 workers()->run_task(&rsfp_task); 4102 4103 // Now restore saved marks, if any. 4104 for (uint i = 0; i < ParallelGCThreads; i++) { 4105 OopAndMarkOopStack& cur = _preserved_objs[i]; 4106 while (!cur.is_empty()) { 4107 OopAndMarkOop elem = cur.pop(); 4108 elem.set_mark(); 4109 } 4110 cur.clear(true); 4111 } 4112 4113 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0); 4114 } 4115 4116 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) { 4117 if (!_evacuation_failed) { 4118 _evacuation_failed = true; 4119 } 4120 4121 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size()); 4122 4123 // We want to call the "for_promotion_failure" version only in the 4124 // case of a promotion failure. 4125 if (m->must_be_preserved_for_promotion_failure(obj)) { 4126 OopAndMarkOop elem(obj, m); 4127 _preserved_objs[worker_id].push(elem); 4128 } 4129 } 4130 4131 class G1ParEvacuateFollowersClosure : public VoidClosure { 4132 private: 4133 double _start_term; 4134 double _term_time; 4135 size_t _term_attempts; 4136 4137 void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); } 4138 void end_term_time() { _term_time += os::elapsedTime() - _start_term; } 4139 protected: 4140 G1CollectedHeap* _g1h; 4141 G1ParScanThreadState* _par_scan_state; 4142 RefToScanQueueSet* _queues; 4143 ParallelTaskTerminator* _terminator; 4144 4145 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 4146 RefToScanQueueSet* queues() { return _queues; } 4147 ParallelTaskTerminator* terminator() { return _terminator; } 4148 4149 public: 4150 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h, 4151 G1ParScanThreadState* par_scan_state, 4152 RefToScanQueueSet* queues, 4153 ParallelTaskTerminator* terminator) 4154 : _g1h(g1h), _par_scan_state(par_scan_state), 4155 _queues(queues), _terminator(terminator), 4156 _start_term(0.0), _term_time(0.0), _term_attempts(0) {} 4157 4158 void do_void(); 4159 4160 double term_time() const { return _term_time; } 4161 size_t term_attempts() const { return _term_attempts; } 4162 4163 private: 4164 inline bool offer_termination(); 4165 }; 4166 4167 bool G1ParEvacuateFollowersClosure::offer_termination() { 4168 G1ParScanThreadState* const pss = par_scan_state(); 4169 start_term_time(); 4170 const bool res = terminator()->offer_termination(); 4171 end_term_time(); 4172 return res; 4173 } 4174 4175 void G1ParEvacuateFollowersClosure::do_void() { 4176 G1ParScanThreadState* const pss = par_scan_state(); 4177 pss->trim_queue(); 4178 do { 4179 pss->steal_and_trim_queue(queues()); 4180 } while (!offer_termination()); 4181 } 4182 4183 class G1ParTask : public AbstractGangTask { 4184 protected: 4185 G1CollectedHeap* _g1h; 4186 G1ParScanThreadStateSet* _pss; 4187 RefToScanQueueSet* _queues; 4188 G1RootProcessor* _root_processor; 4189 ParallelTaskTerminator _terminator; 4190 uint _n_workers; 4191 4192 public: 4193 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers) 4194 : AbstractGangTask("G1 collection"), 4195 _g1h(g1h), 4196 _pss(per_thread_states), 4197 _queues(task_queues), 4198 _root_processor(root_processor), 4199 _terminator(n_workers, _queues), 4200 _n_workers(n_workers) 4201 {} 4202 4203 void work(uint worker_id) { 4204 if (worker_id >= _n_workers) return; // no work needed this round 4205 4206 double start_sec = os::elapsedTime(); 4207 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec); 4208 4209 { 4210 ResourceMark rm; 4211 HandleMark hm; 4212 4213 ReferenceProcessor* rp = _g1h->ref_processor_stw(); 4214 4215 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 4216 pss->set_ref_processor(rp); 4217 4218 double start_strong_roots_sec = os::elapsedTime(); 4219 4220 _root_processor->evacuate_roots(pss->closures(), worker_id); 4221 4222 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, pss); 4223 4224 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid 4225 // treating the nmethods visited to act as roots for concurrent marking. 4226 // We only want to make sure that the oops in the nmethods are adjusted with regard to the 4227 // objects copied by the current evacuation. 4228 size_t cards_scanned = _g1h->g1_rem_set()->oops_into_collection_set_do(&push_heap_rs_cl, 4229 pss->closures()->weak_codeblobs(), 4230 worker_id); 4231 4232 _pss->add_cards_scanned(worker_id, cards_scanned); 4233 4234 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec; 4235 4236 double term_sec = 0.0; 4237 size_t evac_term_attempts = 0; 4238 { 4239 double start = os::elapsedTime(); 4240 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator); 4241 evac.do_void(); 4242 4243 evac_term_attempts = evac.term_attempts(); 4244 term_sec = evac.term_time(); 4245 double elapsed_sec = os::elapsedTime() - start; 4246 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec); 4247 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec); 4248 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts); 4249 } 4250 4251 assert(pss->queue_is_empty(), "should be empty"); 4252 4253 if (PrintTerminationStats) { 4254 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); 4255 size_t lab_waste; 4256 size_t lab_undo_waste; 4257 pss->waste(lab_waste, lab_undo_waste); 4258 _g1h->print_termination_stats(gclog_or_tty, 4259 worker_id, 4260 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */ 4261 strong_roots_sec * 1000.0, /* strong roots time */ 4262 term_sec * 1000.0, /* evac term time */ 4263 evac_term_attempts, /* evac term attempts */ 4264 lab_waste, /* alloc buffer waste */ 4265 lab_undo_waste /* undo waste */ 4266 ); 4267 } 4268 4269 // Close the inner scope so that the ResourceMark and HandleMark 4270 // destructors are executed here and are included as part of the 4271 // "GC Worker Time". 4272 } 4273 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime()); 4274 } 4275 }; 4276 4277 void G1CollectedHeap::print_termination_stats_hdr(outputStream* const st) { 4278 st->print_raw_cr("GC Termination Stats"); 4279 st->print_raw_cr(" elapsed --strong roots-- -------termination------- ------waste (KiB)------"); 4280 st->print_raw_cr("thr ms ms % ms % attempts total alloc undo"); 4281 st->print_raw_cr("--- --------- --------- ------ --------- ------ -------- ------- ------- -------"); 4282 } 4283 4284 void G1CollectedHeap::print_termination_stats(outputStream* const st, 4285 uint worker_id, 4286 double elapsed_ms, 4287 double strong_roots_ms, 4288 double term_ms, 4289 size_t term_attempts, 4290 size_t alloc_buffer_waste, 4291 size_t undo_waste) const { 4292 st->print_cr("%3d %9.2f %9.2f %6.2f " 4293 "%9.2f %6.2f " SIZE_FORMAT_W(8) " " 4294 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7), 4295 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms, 4296 term_ms, term_ms * 100 / elapsed_ms, term_attempts, 4297 (alloc_buffer_waste + undo_waste) * HeapWordSize / K, 4298 alloc_buffer_waste * HeapWordSize / K, 4299 undo_waste * HeapWordSize / K); 4300 } 4301 4302 class G1StringSymbolTableUnlinkTask : public AbstractGangTask { 4303 private: 4304 BoolObjectClosure* _is_alive; 4305 int _initial_string_table_size; 4306 int _initial_symbol_table_size; 4307 4308 bool _process_strings; 4309 int _strings_processed; 4310 int _strings_removed; 4311 4312 bool _process_symbols; 4313 int _symbols_processed; 4314 int _symbols_removed; 4315 4316 public: 4317 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) : 4318 AbstractGangTask("String/Symbol Unlinking"), 4319 _is_alive(is_alive), 4320 _process_strings(process_strings), _strings_processed(0), _strings_removed(0), 4321 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) { 4322 4323 _initial_string_table_size = StringTable::the_table()->table_size(); 4324 _initial_symbol_table_size = SymbolTable::the_table()->table_size(); 4325 if (process_strings) { 4326 StringTable::clear_parallel_claimed_index(); 4327 } 4328 if (process_symbols) { 4329 SymbolTable::clear_parallel_claimed_index(); 4330 } 4331 } 4332 4333 ~G1StringSymbolTableUnlinkTask() { 4334 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size, 4335 "claim value %d after unlink less than initial string table size %d", 4336 StringTable::parallel_claimed_index(), _initial_string_table_size); 4337 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size, 4338 "claim value %d after unlink less than initial symbol table size %d", 4339 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size); 4340 4341 if (G1TraceStringSymbolTableScrubbing) { 4342 gclog_or_tty->print_cr("Cleaned string and symbol table, " 4343 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, " 4344 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed", 4345 strings_processed(), strings_removed(), 4346 symbols_processed(), symbols_removed()); 4347 } 4348 } 4349 4350 void work(uint worker_id) { 4351 int strings_processed = 0; 4352 int strings_removed = 0; 4353 int symbols_processed = 0; 4354 int symbols_removed = 0; 4355 if (_process_strings) { 4356 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed); 4357 Atomic::add(strings_processed, &_strings_processed); 4358 Atomic::add(strings_removed, &_strings_removed); 4359 } 4360 if (_process_symbols) { 4361 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed); 4362 Atomic::add(symbols_processed, &_symbols_processed); 4363 Atomic::add(symbols_removed, &_symbols_removed); 4364 } 4365 } 4366 4367 size_t strings_processed() const { return (size_t)_strings_processed; } 4368 size_t strings_removed() const { return (size_t)_strings_removed; } 4369 4370 size_t symbols_processed() const { return (size_t)_symbols_processed; } 4371 size_t symbols_removed() const { return (size_t)_symbols_removed; } 4372 }; 4373 4374 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC { 4375 private: 4376 static Monitor* _lock; 4377 4378 BoolObjectClosure* const _is_alive; 4379 const bool _unloading_occurred; 4380 const uint _num_workers; 4381 4382 // Variables used to claim nmethods. 4383 nmethod* _first_nmethod; 4384 volatile nmethod* _claimed_nmethod; 4385 4386 // The list of nmethods that need to be processed by the second pass. 4387 volatile nmethod* _postponed_list; 4388 volatile uint _num_entered_barrier; 4389 4390 public: 4391 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) : 4392 _is_alive(is_alive), 4393 _unloading_occurred(unloading_occurred), 4394 _num_workers(num_workers), 4395 _first_nmethod(NULL), 4396 _claimed_nmethod(NULL), 4397 _postponed_list(NULL), 4398 _num_entered_barrier(0) 4399 { 4400 nmethod::increase_unloading_clock(); 4401 // Get first alive nmethod 4402 NMethodIterator iter = NMethodIterator(); 4403 if(iter.next_alive()) { 4404 _first_nmethod = iter.method(); 4405 } 4406 _claimed_nmethod = (volatile nmethod*)_first_nmethod; 4407 } 4408 4409 ~G1CodeCacheUnloadingTask() { 4410 CodeCache::verify_clean_inline_caches(); 4411 4412 CodeCache::set_needs_cache_clean(false); 4413 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be"); 4414 4415 CodeCache::verify_icholder_relocations(); 4416 } 4417 4418 private: 4419 void add_to_postponed_list(nmethod* nm) { 4420 nmethod* old; 4421 do { 4422 old = (nmethod*)_postponed_list; 4423 nm->set_unloading_next(old); 4424 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old); 4425 } 4426 4427 void clean_nmethod(nmethod* nm) { 4428 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred); 4429 4430 if (postponed) { 4431 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet. 4432 add_to_postponed_list(nm); 4433 } 4434 4435 // Mark that this thread has been cleaned/unloaded. 4436 // After this call, it will be safe to ask if this nmethod was unloaded or not. 4437 nm->set_unloading_clock(nmethod::global_unloading_clock()); 4438 } 4439 4440 void clean_nmethod_postponed(nmethod* nm) { 4441 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred); 4442 } 4443 4444 static const int MaxClaimNmethods = 16; 4445 4446 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) { 4447 nmethod* first; 4448 NMethodIterator last; 4449 4450 do { 4451 *num_claimed_nmethods = 0; 4452 4453 first = (nmethod*)_claimed_nmethod; 4454 last = NMethodIterator(first); 4455 4456 if (first != NULL) { 4457 4458 for (int i = 0; i < MaxClaimNmethods; i++) { 4459 if (!last.next_alive()) { 4460 break; 4461 } 4462 claimed_nmethods[i] = last.method(); 4463 (*num_claimed_nmethods)++; 4464 } 4465 } 4466 4467 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first); 4468 } 4469 4470 nmethod* claim_postponed_nmethod() { 4471 nmethod* claim; 4472 nmethod* next; 4473 4474 do { 4475 claim = (nmethod*)_postponed_list; 4476 if (claim == NULL) { 4477 return NULL; 4478 } 4479 4480 next = claim->unloading_next(); 4481 4482 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim); 4483 4484 return claim; 4485 } 4486 4487 public: 4488 // Mark that we're done with the first pass of nmethod cleaning. 4489 void barrier_mark(uint worker_id) { 4490 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 4491 _num_entered_barrier++; 4492 if (_num_entered_barrier == _num_workers) { 4493 ml.notify_all(); 4494 } 4495 } 4496 4497 // See if we have to wait for the other workers to 4498 // finish their first-pass nmethod cleaning work. 4499 void barrier_wait(uint worker_id) { 4500 if (_num_entered_barrier < _num_workers) { 4501 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 4502 while (_num_entered_barrier < _num_workers) { 4503 ml.wait(Mutex::_no_safepoint_check_flag, 0, false); 4504 } 4505 } 4506 } 4507 4508 // Cleaning and unloading of nmethods. Some work has to be postponed 4509 // to the second pass, when we know which nmethods survive. 4510 void work_first_pass(uint worker_id) { 4511 // The first nmethods is claimed by the first worker. 4512 if (worker_id == 0 && _first_nmethod != NULL) { 4513 clean_nmethod(_first_nmethod); 4514 _first_nmethod = NULL; 4515 } 4516 4517 int num_claimed_nmethods; 4518 nmethod* claimed_nmethods[MaxClaimNmethods]; 4519 4520 while (true) { 4521 claim_nmethods(claimed_nmethods, &num_claimed_nmethods); 4522 4523 if (num_claimed_nmethods == 0) { 4524 break; 4525 } 4526 4527 for (int i = 0; i < num_claimed_nmethods; i++) { 4528 clean_nmethod(claimed_nmethods[i]); 4529 } 4530 } 4531 } 4532 4533 void work_second_pass(uint worker_id) { 4534 nmethod* nm; 4535 // Take care of postponed nmethods. 4536 while ((nm = claim_postponed_nmethod()) != NULL) { 4537 clean_nmethod_postponed(nm); 4538 } 4539 } 4540 }; 4541 4542 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never); 4543 4544 class G1KlassCleaningTask : public StackObj { 4545 BoolObjectClosure* _is_alive; 4546 volatile jint _clean_klass_tree_claimed; 4547 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator; 4548 4549 public: 4550 G1KlassCleaningTask(BoolObjectClosure* is_alive) : 4551 _is_alive(is_alive), 4552 _clean_klass_tree_claimed(0), 4553 _klass_iterator() { 4554 } 4555 4556 private: 4557 bool claim_clean_klass_tree_task() { 4558 if (_clean_klass_tree_claimed) { 4559 return false; 4560 } 4561 4562 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0; 4563 } 4564 4565 InstanceKlass* claim_next_klass() { 4566 Klass* klass; 4567 do { 4568 klass =_klass_iterator.next_klass(); 4569 } while (klass != NULL && !klass->is_instance_klass()); 4570 4571 // this can be null so don't call InstanceKlass::cast 4572 return static_cast<InstanceKlass*>(klass); 4573 } 4574 4575 public: 4576 4577 void clean_klass(InstanceKlass* ik) { 4578 ik->clean_weak_instanceklass_links(_is_alive); 4579 } 4580 4581 void work() { 4582 ResourceMark rm; 4583 4584 // One worker will clean the subklass/sibling klass tree. 4585 if (claim_clean_klass_tree_task()) { 4586 Klass::clean_subklass_tree(_is_alive); 4587 } 4588 4589 // All workers will help cleaning the classes, 4590 InstanceKlass* klass; 4591 while ((klass = claim_next_klass()) != NULL) { 4592 clean_klass(klass); 4593 } 4594 } 4595 }; 4596 4597 // To minimize the remark pause times, the tasks below are done in parallel. 4598 class G1ParallelCleaningTask : public AbstractGangTask { 4599 private: 4600 G1StringSymbolTableUnlinkTask _string_symbol_task; 4601 G1CodeCacheUnloadingTask _code_cache_task; 4602 G1KlassCleaningTask _klass_cleaning_task; 4603 4604 public: 4605 // The constructor is run in the VMThread. 4606 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) : 4607 AbstractGangTask("Parallel Cleaning"), 4608 _string_symbol_task(is_alive, process_strings, process_symbols), 4609 _code_cache_task(num_workers, is_alive, unloading_occurred), 4610 _klass_cleaning_task(is_alive) { 4611 } 4612 4613 // The parallel work done by all worker threads. 4614 void work(uint worker_id) { 4615 // Do first pass of code cache cleaning. 4616 _code_cache_task.work_first_pass(worker_id); 4617 4618 // Let the threads mark that the first pass is done. 4619 _code_cache_task.barrier_mark(worker_id); 4620 4621 // Clean the Strings and Symbols. 4622 _string_symbol_task.work(worker_id); 4623 4624 // Wait for all workers to finish the first code cache cleaning pass. 4625 _code_cache_task.barrier_wait(worker_id); 4626 4627 // Do the second code cache cleaning work, which realize on 4628 // the liveness information gathered during the first pass. 4629 _code_cache_task.work_second_pass(worker_id); 4630 4631 // Clean all klasses that were not unloaded. 4632 _klass_cleaning_task.work(); 4633 } 4634 }; 4635 4636 4637 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive, 4638 bool process_strings, 4639 bool process_symbols, 4640 bool class_unloading_occurred) { 4641 uint n_workers = workers()->active_workers(); 4642 4643 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, 4644 n_workers, class_unloading_occurred); 4645 workers()->run_task(&g1_unlink_task); 4646 } 4647 4648 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive, 4649 bool process_strings, bool process_symbols) { 4650 { 4651 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols); 4652 workers()->run_task(&g1_unlink_task); 4653 } 4654 4655 if (G1StringDedup::is_enabled()) { 4656 G1StringDedup::unlink(is_alive); 4657 } 4658 } 4659 4660 class G1RedirtyLoggedCardsTask : public AbstractGangTask { 4661 private: 4662 DirtyCardQueueSet* _queue; 4663 public: 4664 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { } 4665 4666 virtual void work(uint worker_id) { 4667 G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times(); 4668 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id); 4669 4670 RedirtyLoggedCardTableEntryClosure cl; 4671 _queue->par_apply_closure_to_all_completed_buffers(&cl); 4672 4673 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed()); 4674 } 4675 }; 4676 4677 void G1CollectedHeap::redirty_logged_cards() { 4678 double redirty_logged_cards_start = os::elapsedTime(); 4679 4680 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set()); 4681 dirty_card_queue_set().reset_for_par_iteration(); 4682 workers()->run_task(&redirty_task); 4683 4684 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set(); 4685 dcq.merge_bufferlists(&dirty_card_queue_set()); 4686 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed"); 4687 4688 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0); 4689 } 4690 4691 // Weak Reference Processing support 4692 4693 // An always "is_alive" closure that is used to preserve referents. 4694 // If the object is non-null then it's alive. Used in the preservation 4695 // of referent objects that are pointed to by reference objects 4696 // discovered by the CM ref processor. 4697 class G1AlwaysAliveClosure: public BoolObjectClosure { 4698 G1CollectedHeap* _g1; 4699 public: 4700 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 4701 bool do_object_b(oop p) { 4702 if (p != NULL) { 4703 return true; 4704 } 4705 return false; 4706 } 4707 }; 4708 4709 bool G1STWIsAliveClosure::do_object_b(oop p) { 4710 // An object is reachable if it is outside the collection set, 4711 // or is inside and copied. 4712 return !_g1->is_in_cset(p) || p->is_forwarded(); 4713 } 4714 4715 // Non Copying Keep Alive closure 4716 class G1KeepAliveClosure: public OopClosure { 4717 G1CollectedHeap* _g1; 4718 public: 4719 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 4720 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } 4721 void do_oop(oop* p) { 4722 oop obj = *p; 4723 assert(obj != NULL, "the caller should have filtered out NULL values"); 4724 4725 const InCSetState cset_state = _g1->in_cset_state(obj); 4726 if (!cset_state.is_in_cset_or_humongous()) { 4727 return; 4728 } 4729 if (cset_state.is_in_cset()) { 4730 assert( obj->is_forwarded(), "invariant" ); 4731 *p = obj->forwardee(); 4732 } else { 4733 assert(!obj->is_forwarded(), "invariant" ); 4734 assert(cset_state.is_humongous(), 4735 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value()); 4736 _g1->set_humongous_is_live(obj); 4737 } 4738 } 4739 }; 4740 4741 // Copying Keep Alive closure - can be called from both 4742 // serial and parallel code as long as different worker 4743 // threads utilize different G1ParScanThreadState instances 4744 // and different queues. 4745 4746 class G1CopyingKeepAliveClosure: public OopClosure { 4747 G1CollectedHeap* _g1h; 4748 OopClosure* _copy_non_heap_obj_cl; 4749 G1ParScanThreadState* _par_scan_state; 4750 4751 public: 4752 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, 4753 OopClosure* non_heap_obj_cl, 4754 G1ParScanThreadState* pss): 4755 _g1h(g1h), 4756 _copy_non_heap_obj_cl(non_heap_obj_cl), 4757 _par_scan_state(pss) 4758 {} 4759 4760 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 4761 virtual void do_oop( oop* p) { do_oop_work(p); } 4762 4763 template <class T> void do_oop_work(T* p) { 4764 oop obj = oopDesc::load_decode_heap_oop(p); 4765 4766 if (_g1h->is_in_cset_or_humongous(obj)) { 4767 // If the referent object has been forwarded (either copied 4768 // to a new location or to itself in the event of an 4769 // evacuation failure) then we need to update the reference 4770 // field and, if both reference and referent are in the G1 4771 // heap, update the RSet for the referent. 4772 // 4773 // If the referent has not been forwarded then we have to keep 4774 // it alive by policy. Therefore we have copy the referent. 4775 // 4776 // If the reference field is in the G1 heap then we can push 4777 // on the PSS queue. When the queue is drained (after each 4778 // phase of reference processing) the object and it's followers 4779 // will be copied, the reference field set to point to the 4780 // new location, and the RSet updated. Otherwise we need to 4781 // use the the non-heap or metadata closures directly to copy 4782 // the referent object and update the pointer, while avoiding 4783 // updating the RSet. 4784 4785 if (_g1h->is_in_g1_reserved(p)) { 4786 _par_scan_state->push_on_queue(p); 4787 } else { 4788 assert(!Metaspace::contains((const void*)p), 4789 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p)); 4790 _copy_non_heap_obj_cl->do_oop(p); 4791 } 4792 } 4793 } 4794 }; 4795 4796 // Serial drain queue closure. Called as the 'complete_gc' 4797 // closure for each discovered list in some of the 4798 // reference processing phases. 4799 4800 class G1STWDrainQueueClosure: public VoidClosure { 4801 protected: 4802 G1CollectedHeap* _g1h; 4803 G1ParScanThreadState* _par_scan_state; 4804 4805 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 4806 4807 public: 4808 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : 4809 _g1h(g1h), 4810 _par_scan_state(pss) 4811 { } 4812 4813 void do_void() { 4814 G1ParScanThreadState* const pss = par_scan_state(); 4815 pss->trim_queue(); 4816 } 4817 }; 4818 4819 // Parallel Reference Processing closures 4820 4821 // Implementation of AbstractRefProcTaskExecutor for parallel reference 4822 // processing during G1 evacuation pauses. 4823 4824 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 4825 private: 4826 G1CollectedHeap* _g1h; 4827 G1ParScanThreadStateSet* _pss; 4828 RefToScanQueueSet* _queues; 4829 WorkGang* _workers; 4830 uint _active_workers; 4831 4832 public: 4833 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, 4834 G1ParScanThreadStateSet* per_thread_states, 4835 WorkGang* workers, 4836 RefToScanQueueSet *task_queues, 4837 uint n_workers) : 4838 _g1h(g1h), 4839 _pss(per_thread_states), 4840 _queues(task_queues), 4841 _workers(workers), 4842 _active_workers(n_workers) 4843 { 4844 assert(n_workers > 0, "shouldn't call this otherwise"); 4845 } 4846 4847 // Executes the given task using concurrent marking worker threads. 4848 virtual void execute(ProcessTask& task); 4849 virtual void execute(EnqueueTask& task); 4850 }; 4851 4852 // Gang task for possibly parallel reference processing 4853 4854 class G1STWRefProcTaskProxy: public AbstractGangTask { 4855 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 4856 ProcessTask& _proc_task; 4857 G1CollectedHeap* _g1h; 4858 G1ParScanThreadStateSet* _pss; 4859 RefToScanQueueSet* _task_queues; 4860 ParallelTaskTerminator* _terminator; 4861 4862 public: 4863 G1STWRefProcTaskProxy(ProcessTask& proc_task, 4864 G1CollectedHeap* g1h, 4865 G1ParScanThreadStateSet* per_thread_states, 4866 RefToScanQueueSet *task_queues, 4867 ParallelTaskTerminator* terminator) : 4868 AbstractGangTask("Process reference objects in parallel"), 4869 _proc_task(proc_task), 4870 _g1h(g1h), 4871 _pss(per_thread_states), 4872 _task_queues(task_queues), 4873 _terminator(terminator) 4874 {} 4875 4876 virtual void work(uint worker_id) { 4877 // The reference processing task executed by a single worker. 4878 ResourceMark rm; 4879 HandleMark hm; 4880 4881 G1STWIsAliveClosure is_alive(_g1h); 4882 4883 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 4884 pss->set_ref_processor(NULL); 4885 4886 // Keep alive closure. 4887 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss); 4888 4889 // Complete GC closure 4890 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator); 4891 4892 // Call the reference processing task's work routine. 4893 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); 4894 4895 // Note we cannot assert that the refs array is empty here as not all 4896 // of the processing tasks (specifically phase2 - pp2_work) execute 4897 // the complete_gc closure (which ordinarily would drain the queue) so 4898 // the queue may not be empty. 4899 } 4900 }; 4901 4902 // Driver routine for parallel reference processing. 4903 // Creates an instance of the ref processing gang 4904 // task and has the worker threads execute it. 4905 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) { 4906 assert(_workers != NULL, "Need parallel worker threads."); 4907 4908 ParallelTaskTerminator terminator(_active_workers, _queues); 4909 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator); 4910 4911 _workers->run_task(&proc_task_proxy); 4912 } 4913 4914 // Gang task for parallel reference enqueueing. 4915 4916 class G1STWRefEnqueueTaskProxy: public AbstractGangTask { 4917 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; 4918 EnqueueTask& _enq_task; 4919 4920 public: 4921 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) : 4922 AbstractGangTask("Enqueue reference objects in parallel"), 4923 _enq_task(enq_task) 4924 { } 4925 4926 virtual void work(uint worker_id) { 4927 _enq_task.work(worker_id); 4928 } 4929 }; 4930 4931 // Driver routine for parallel reference enqueueing. 4932 // Creates an instance of the ref enqueueing gang 4933 // task and has the worker threads execute it. 4934 4935 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) { 4936 assert(_workers != NULL, "Need parallel worker threads."); 4937 4938 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task); 4939 4940 _workers->run_task(&enq_task_proxy); 4941 } 4942 4943 // End of weak reference support closures 4944 4945 // Abstract task used to preserve (i.e. copy) any referent objects 4946 // that are in the collection set and are pointed to by reference 4947 // objects discovered by the CM ref processor. 4948 4949 class G1ParPreserveCMReferentsTask: public AbstractGangTask { 4950 protected: 4951 G1CollectedHeap* _g1h; 4952 G1ParScanThreadStateSet* _pss; 4953 RefToScanQueueSet* _queues; 4954 ParallelTaskTerminator _terminator; 4955 uint _n_workers; 4956 4957 public: 4958 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) : 4959 AbstractGangTask("ParPreserveCMReferents"), 4960 _g1h(g1h), 4961 _pss(per_thread_states), 4962 _queues(task_queues), 4963 _terminator(workers, _queues), 4964 _n_workers(workers) 4965 { } 4966 4967 void work(uint worker_id) { 4968 ResourceMark rm; 4969 HandleMark hm; 4970 4971 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 4972 pss->set_ref_processor(NULL); 4973 assert(pss->queue_is_empty(), "both queue and overflow should be empty"); 4974 4975 // Is alive closure 4976 G1AlwaysAliveClosure always_alive(_g1h); 4977 4978 // Copying keep alive closure. Applied to referent objects that need 4979 // to be copied. 4980 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss); 4981 4982 ReferenceProcessor* rp = _g1h->ref_processor_cm(); 4983 4984 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q(); 4985 uint stride = MIN2(MAX2(_n_workers, 1U), limit); 4986 4987 // limit is set using max_num_q() - which was set using ParallelGCThreads. 4988 // So this must be true - but assert just in case someone decides to 4989 // change the worker ids. 4990 assert(worker_id < limit, "sanity"); 4991 assert(!rp->discovery_is_atomic(), "check this code"); 4992 4993 // Select discovered lists [i, i+stride, i+2*stride,...,limit) 4994 for (uint idx = worker_id; idx < limit; idx += stride) { 4995 DiscoveredList& ref_list = rp->discovered_refs()[idx]; 4996 4997 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive); 4998 while (iter.has_next()) { 4999 // Since discovery is not atomic for the CM ref processor, we 5000 // can see some null referent objects. 5001 iter.load_ptrs(DEBUG_ONLY(true)); 5002 oop ref = iter.obj(); 5003 5004 // This will filter nulls. 5005 if (iter.is_referent_alive()) { 5006 iter.make_referent_alive(); 5007 } 5008 iter.move_to_next(); 5009 } 5010 } 5011 5012 // Drain the queue - which may cause stealing 5013 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator); 5014 drain_queue.do_void(); 5015 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure 5016 assert(pss->queue_is_empty(), "should be"); 5017 } 5018 }; 5019 5020 // Weak Reference processing during an evacuation pause (part 1). 5021 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) { 5022 double ref_proc_start = os::elapsedTime(); 5023 5024 ReferenceProcessor* rp = _ref_processor_stw; 5025 assert(rp->discovery_enabled(), "should have been enabled"); 5026 5027 // Any reference objects, in the collection set, that were 'discovered' 5028 // by the CM ref processor should have already been copied (either by 5029 // applying the external root copy closure to the discovered lists, or 5030 // by following an RSet entry). 5031 // 5032 // But some of the referents, that are in the collection set, that these 5033 // reference objects point to may not have been copied: the STW ref 5034 // processor would have seen that the reference object had already 5035 // been 'discovered' and would have skipped discovering the reference, 5036 // but would not have treated the reference object as a regular oop. 5037 // As a result the copy closure would not have been applied to the 5038 // referent object. 5039 // 5040 // We need to explicitly copy these referent objects - the references 5041 // will be processed at the end of remarking. 5042 // 5043 // We also need to do this copying before we process the reference 5044 // objects discovered by the STW ref processor in case one of these 5045 // referents points to another object which is also referenced by an 5046 // object discovered by the STW ref processor. 5047 5048 uint no_of_gc_workers = workers()->active_workers(); 5049 5050 G1ParPreserveCMReferentsTask keep_cm_referents(this, 5051 per_thread_states, 5052 no_of_gc_workers, 5053 _task_queues); 5054 5055 workers()->run_task(&keep_cm_referents); 5056 5057 // Closure to test whether a referent is alive. 5058 G1STWIsAliveClosure is_alive(this); 5059 5060 // Even when parallel reference processing is enabled, the processing 5061 // of JNI refs is serial and performed serially by the current thread 5062 // rather than by a worker. The following PSS will be used for processing 5063 // JNI refs. 5064 5065 // Use only a single queue for this PSS. 5066 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0); 5067 pss->set_ref_processor(NULL); 5068 assert(pss->queue_is_empty(), "pre-condition"); 5069 5070 // Keep alive closure. 5071 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss); 5072 5073 // Serial Complete GC closure 5074 G1STWDrainQueueClosure drain_queue(this, pss); 5075 5076 // Setup the soft refs policy... 5077 rp->setup_policy(false); 5078 5079 ReferenceProcessorStats stats; 5080 if (!rp->processing_is_mt()) { 5081 // Serial reference processing... 5082 stats = rp->process_discovered_references(&is_alive, 5083 &keep_alive, 5084 &drain_queue, 5085 NULL, 5086 _gc_timer_stw); 5087 } else { 5088 // Parallel reference processing 5089 assert(rp->num_q() == no_of_gc_workers, "sanity"); 5090 assert(no_of_gc_workers <= rp->max_num_q(), "sanity"); 5091 5092 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers); 5093 stats = rp->process_discovered_references(&is_alive, 5094 &keep_alive, 5095 &drain_queue, 5096 &par_task_executor, 5097 _gc_timer_stw); 5098 } 5099 5100 _gc_tracer_stw->report_gc_reference_stats(stats); 5101 5102 // We have completed copying any necessary live referent objects. 5103 assert(pss->queue_is_empty(), "both queue and overflow should be empty"); 5104 5105 double ref_proc_time = os::elapsedTime() - ref_proc_start; 5106 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 5107 } 5108 5109 // Weak Reference processing during an evacuation pause (part 2). 5110 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) { 5111 double ref_enq_start = os::elapsedTime(); 5112 5113 ReferenceProcessor* rp = _ref_processor_stw; 5114 assert(!rp->discovery_enabled(), "should have been disabled as part of processing"); 5115 5116 // Now enqueue any remaining on the discovered lists on to 5117 // the pending list. 5118 if (!rp->processing_is_mt()) { 5119 // Serial reference processing... 5120 rp->enqueue_discovered_references(); 5121 } else { 5122 // Parallel reference enqueueing 5123 5124 uint n_workers = workers()->active_workers(); 5125 5126 assert(rp->num_q() == n_workers, "sanity"); 5127 assert(n_workers <= rp->max_num_q(), "sanity"); 5128 5129 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers); 5130 rp->enqueue_discovered_references(&par_task_executor); 5131 } 5132 5133 rp->verify_no_references_recorded(); 5134 assert(!rp->discovery_enabled(), "should have been disabled"); 5135 5136 // FIXME 5137 // CM's reference processing also cleans up the string and symbol tables. 5138 // Should we do that here also? We could, but it is a serial operation 5139 // and could significantly increase the pause time. 5140 5141 double ref_enq_time = os::elapsedTime() - ref_enq_start; 5142 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0); 5143 } 5144 5145 void G1CollectedHeap::pre_evacuate_collection_set() { 5146 _expand_heap_after_alloc_failure = true; 5147 _evacuation_failed = false; 5148 5149 // Disable the hot card cache. 5150 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 5151 hot_card_cache->reset_hot_cache_claimed_index(); 5152 hot_card_cache->set_use_cache(false); 5153 5154 } 5155 5156 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) { 5157 g1_rem_set()->prepare_for_oops_into_collection_set_do(); 5158 5159 // Should G1EvacuationFailureALot be in effect for this GC? 5160 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) 5161 5162 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty"); 5163 double start_par_time_sec = os::elapsedTime(); 5164 double end_par_time_sec; 5165 5166 { 5167 const uint n_workers = workers()->active_workers(); 5168 G1RootProcessor root_processor(this, n_workers); 5169 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers); 5170 // InitialMark needs claim bits to keep track of the marked-through CLDs. 5171 if (collector_state()->during_initial_mark_pause()) { 5172 ClassLoaderDataGraph::clear_claimed_marks(); 5173 } 5174 5175 // The individual threads will set their evac-failure closures. 5176 if (PrintTerminationStats) { 5177 print_termination_stats_hdr(gclog_or_tty); 5178 } 5179 5180 workers()->run_task(&g1_par_task); 5181 end_par_time_sec = os::elapsedTime(); 5182 5183 // Closing the inner scope will execute the destructor 5184 // for the G1RootProcessor object. We record the current 5185 // elapsed time before closing the scope so that time 5186 // taken for the destructor is NOT included in the 5187 // reported parallel time. 5188 } 5189 5190 G1GCPhaseTimes* phase_times = g1_policy()->phase_times(); 5191 5192 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0; 5193 phase_times->record_par_time(par_time_ms); 5194 5195 double code_root_fixup_time_ms = 5196 (os::elapsedTime() - end_par_time_sec) * 1000.0; 5197 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms); 5198 5199 // Process any discovered reference objects - we have 5200 // to do this _before_ we retire the GC alloc regions 5201 // as we may have to copy some 'reachable' referent 5202 // objects (and their reachable sub-graphs) that were 5203 // not copied during the pause. 5204 process_discovered_references(per_thread_states); 5205 5206 if (G1StringDedup::is_enabled()) { 5207 double fixup_start = os::elapsedTime(); 5208 5209 G1STWIsAliveClosure is_alive(this); 5210 G1KeepAliveClosure keep_alive(this); 5211 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times); 5212 5213 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0; 5214 phase_times->record_string_dedup_fixup_time(fixup_time_ms); 5215 } 5216 5217 g1_rem_set()->cleanup_after_oops_into_collection_set_do(); 5218 5219 if (evacuation_failed()) { 5220 remove_self_forwarding_pointers(); 5221 5222 // Reset the G1EvacuationFailureALot counters and flags 5223 // Note: the values are reset only when an actual 5224 // evacuation failure occurs. 5225 NOT_PRODUCT(reset_evacuation_should_fail();) 5226 } 5227 5228 // Enqueue any remaining references remaining on the STW 5229 // reference processor's discovered lists. We need to do 5230 // this after the card table is cleaned (and verified) as 5231 // the act of enqueueing entries on to the pending list 5232 // will log these updates (and dirty their associated 5233 // cards). We need these updates logged to update any 5234 // RSets. 5235 enqueue_discovered_references(per_thread_states); 5236 } 5237 5238 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) { 5239 _allocator->release_gc_alloc_regions(evacuation_info); 5240 5241 per_thread_states->flush(); 5242 5243 record_obj_copy_mem_stats(); 5244 5245 // Reset and re-enable the hot card cache. 5246 // Note the counts for the cards in the regions in the 5247 // collection set are reset when the collection set is freed. 5248 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 5249 hot_card_cache->reset_hot_cache(); 5250 hot_card_cache->set_use_cache(true); 5251 5252 purge_code_root_memory(); 5253 5254 redirty_logged_cards(); 5255 #if defined(COMPILER2) || INCLUDE_JVMCI 5256 DerivedPointerTable::update_pointers(); 5257 #endif 5258 } 5259 5260 void G1CollectedHeap::record_obj_copy_mem_stats() { 5261 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats), 5262 create_g1_evac_summary(&_old_evac_stats)); 5263 } 5264 5265 void G1CollectedHeap::free_region(HeapRegion* hr, 5266 FreeRegionList* free_list, 5267 bool par, 5268 bool locked) { 5269 assert(!hr->is_free(), "the region should not be free"); 5270 assert(!hr->is_empty(), "the region should not be empty"); 5271 assert(_hrm.is_available(hr->hrm_index()), "region should be committed"); 5272 assert(free_list != NULL, "pre-condition"); 5273 5274 if (G1VerifyBitmaps) { 5275 MemRegion mr(hr->bottom(), hr->end()); 5276 concurrent_mark()->clearRangePrevBitmap(mr); 5277 } 5278 5279 // Clear the card counts for this region. 5280 // Note: we only need to do this if the region is not young 5281 // (since we don't refine cards in young regions). 5282 if (!hr->is_young()) { 5283 _cg1r->hot_card_cache()->reset_card_counts(hr); 5284 } 5285 hr->hr_clear(par, true /* clear_space */, locked /* locked */); 5286 free_list->add_ordered(hr); 5287 } 5288 5289 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 5290 FreeRegionList* free_list, 5291 bool par) { 5292 assert(hr->is_humongous(), "this is only for humongous regions"); 5293 assert(free_list != NULL, "pre-condition"); 5294 hr->clear_humongous(); 5295 free_region(hr, free_list, par); 5296 } 5297 5298 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed, 5299 const HeapRegionSetCount& humongous_regions_removed) { 5300 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) { 5301 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 5302 _old_set.bulk_remove(old_regions_removed); 5303 _humongous_set.bulk_remove(humongous_regions_removed); 5304 } 5305 5306 } 5307 5308 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) { 5309 assert(list != NULL, "list can't be null"); 5310 if (!list->is_empty()) { 5311 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag); 5312 _hrm.insert_list_into_free_list(list); 5313 } 5314 } 5315 5316 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) { 5317 decrease_used(bytes); 5318 } 5319 5320 class G1ParCleanupCTTask : public AbstractGangTask { 5321 G1SATBCardTableModRefBS* _ct_bs; 5322 G1CollectedHeap* _g1h; 5323 HeapRegion* volatile _su_head; 5324 public: 5325 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs, 5326 G1CollectedHeap* g1h) : 5327 AbstractGangTask("G1 Par Cleanup CT Task"), 5328 _ct_bs(ct_bs), _g1h(g1h) { } 5329 5330 void work(uint worker_id) { 5331 HeapRegion* r; 5332 while (r = _g1h->pop_dirty_cards_region()) { 5333 clear_cards(r); 5334 } 5335 } 5336 5337 void clear_cards(HeapRegion* r) { 5338 // Cards of the survivors should have already been dirtied. 5339 if (!r->is_survivor()) { 5340 _ct_bs->clear(MemRegion(r->bottom(), r->end())); 5341 } 5342 } 5343 }; 5344 5345 #ifndef PRODUCT 5346 class G1VerifyCardTableCleanup: public HeapRegionClosure { 5347 G1CollectedHeap* _g1h; 5348 G1SATBCardTableModRefBS* _ct_bs; 5349 public: 5350 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs) 5351 : _g1h(g1h), _ct_bs(ct_bs) { } 5352 virtual bool doHeapRegion(HeapRegion* r) { 5353 if (r->is_survivor()) { 5354 _g1h->verify_dirty_region(r); 5355 } else { 5356 _g1h->verify_not_dirty_region(r); 5357 } 5358 return false; 5359 } 5360 }; 5361 5362 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) { 5363 // All of the region should be clean. 5364 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5365 MemRegion mr(hr->bottom(), hr->end()); 5366 ct_bs->verify_not_dirty_region(mr); 5367 } 5368 5369 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) { 5370 // We cannot guarantee that [bottom(),end()] is dirty. Threads 5371 // dirty allocated blocks as they allocate them. The thread that 5372 // retires each region and replaces it with a new one will do a 5373 // maximal allocation to fill in [pre_dummy_top(),end()] but will 5374 // not dirty that area (one less thing to have to do while holding 5375 // a lock). So we can only verify that [bottom(),pre_dummy_top()] 5376 // is dirty. 5377 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5378 MemRegion mr(hr->bottom(), hr->pre_dummy_top()); 5379 if (hr->is_young()) { 5380 ct_bs->verify_g1_young_region(mr); 5381 } else { 5382 ct_bs->verify_dirty_region(mr); 5383 } 5384 } 5385 5386 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) { 5387 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5388 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) { 5389 verify_dirty_region(hr); 5390 } 5391 } 5392 5393 void G1CollectedHeap::verify_dirty_young_regions() { 5394 verify_dirty_young_list(_young_list->first_region()); 5395 } 5396 5397 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap, 5398 HeapWord* tams, HeapWord* end) { 5399 guarantee(tams <= end, 5400 "tams: " PTR_FORMAT " end: " PTR_FORMAT, p2i(tams), p2i(end)); 5401 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end); 5402 if (result < end) { 5403 gclog_or_tty->cr(); 5404 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: " PTR_FORMAT, 5405 bitmap_name, p2i(result)); 5406 gclog_or_tty->print_cr("## %s tams: " PTR_FORMAT " end: " PTR_FORMAT, 5407 bitmap_name, p2i(tams), p2i(end)); 5408 return false; 5409 } 5410 return true; 5411 } 5412 5413 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) { 5414 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap(); 5415 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap(); 5416 5417 HeapWord* bottom = hr->bottom(); 5418 HeapWord* ptams = hr->prev_top_at_mark_start(); 5419 HeapWord* ntams = hr->next_top_at_mark_start(); 5420 HeapWord* end = hr->end(); 5421 5422 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end); 5423 5424 bool res_n = true; 5425 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window 5426 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap 5427 // if we happen to be in that state. 5428 if (collector_state()->mark_in_progress() || !_cmThread->in_progress()) { 5429 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end); 5430 } 5431 if (!res_p || !res_n) { 5432 gclog_or_tty->print_cr("#### Bitmap verification failed for " HR_FORMAT, 5433 HR_FORMAT_PARAMS(hr)); 5434 gclog_or_tty->print_cr("#### Caller: %s", caller); 5435 return false; 5436 } 5437 return true; 5438 } 5439 5440 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) { 5441 if (!G1VerifyBitmaps) return; 5442 5443 guarantee(verify_bitmaps(caller, hr), "bitmap verification"); 5444 } 5445 5446 class G1VerifyBitmapClosure : public HeapRegionClosure { 5447 private: 5448 const char* _caller; 5449 G1CollectedHeap* _g1h; 5450 bool _failures; 5451 5452 public: 5453 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) : 5454 _caller(caller), _g1h(g1h), _failures(false) { } 5455 5456 bool failures() { return _failures; } 5457 5458 virtual bool doHeapRegion(HeapRegion* hr) { 5459 bool result = _g1h->verify_bitmaps(_caller, hr); 5460 if (!result) { 5461 _failures = true; 5462 } 5463 return false; 5464 } 5465 }; 5466 5467 void G1CollectedHeap::check_bitmaps(const char* caller) { 5468 if (!G1VerifyBitmaps) return; 5469 5470 G1VerifyBitmapClosure cl(caller, this); 5471 heap_region_iterate(&cl); 5472 guarantee(!cl.failures(), "bitmap verification"); 5473 } 5474 5475 class G1CheckCSetFastTableClosure : public HeapRegionClosure { 5476 private: 5477 bool _failures; 5478 public: 5479 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { } 5480 5481 virtual bool doHeapRegion(HeapRegion* hr) { 5482 uint i = hr->hrm_index(); 5483 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i); 5484 if (hr->is_humongous()) { 5485 if (hr->in_collection_set()) { 5486 gclog_or_tty->print_cr("\n## humongous region %u in CSet", i); 5487 _failures = true; 5488 return true; 5489 } 5490 if (cset_state.is_in_cset()) { 5491 gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i); 5492 _failures = true; 5493 return true; 5494 } 5495 if (hr->is_continues_humongous() && cset_state.is_humongous()) { 5496 gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i); 5497 _failures = true; 5498 return true; 5499 } 5500 } else { 5501 if (cset_state.is_humongous()) { 5502 gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i); 5503 _failures = true; 5504 return true; 5505 } 5506 if (hr->in_collection_set() != cset_state.is_in_cset()) { 5507 gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u", 5508 hr->in_collection_set(), cset_state.value(), i); 5509 _failures = true; 5510 return true; 5511 } 5512 if (cset_state.is_in_cset()) { 5513 if (hr->is_young() != (cset_state.is_young())) { 5514 gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u", 5515 hr->is_young(), cset_state.value(), i); 5516 _failures = true; 5517 return true; 5518 } 5519 if (hr->is_old() != (cset_state.is_old())) { 5520 gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u", 5521 hr->is_old(), cset_state.value(), i); 5522 _failures = true; 5523 return true; 5524 } 5525 } 5526 } 5527 return false; 5528 } 5529 5530 bool failures() const { return _failures; } 5531 }; 5532 5533 bool G1CollectedHeap::check_cset_fast_test() { 5534 G1CheckCSetFastTableClosure cl; 5535 _hrm.iterate(&cl); 5536 return !cl.failures(); 5537 } 5538 #endif // PRODUCT 5539 5540 void G1CollectedHeap::cleanUpCardTable() { 5541 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5542 double start = os::elapsedTime(); 5543 5544 { 5545 // Iterate over the dirty cards region list. 5546 G1ParCleanupCTTask cleanup_task(ct_bs, this); 5547 5548 workers()->run_task(&cleanup_task); 5549 #ifndef PRODUCT 5550 if (G1VerifyCTCleanup || VerifyAfterGC) { 5551 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs); 5552 heap_region_iterate(&cleanup_verifier); 5553 } 5554 #endif 5555 } 5556 5557 double elapsed = os::elapsedTime() - start; 5558 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0); 5559 } 5560 5561 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) { 5562 size_t pre_used = 0; 5563 FreeRegionList local_free_list("Local List for CSet Freeing"); 5564 5565 double young_time_ms = 0.0; 5566 double non_young_time_ms = 0.0; 5567 5568 // Since the collection set is a superset of the the young list, 5569 // all we need to do to clear the young list is clear its 5570 // head and length, and unlink any young regions in the code below 5571 _young_list->clear(); 5572 5573 G1CollectorPolicy* policy = g1_policy(); 5574 5575 double start_sec = os::elapsedTime(); 5576 bool non_young = true; 5577 5578 HeapRegion* cur = cs_head; 5579 int age_bound = -1; 5580 size_t rs_lengths = 0; 5581 5582 while (cur != NULL) { 5583 assert(!is_on_master_free_list(cur), "sanity"); 5584 if (non_young) { 5585 if (cur->is_young()) { 5586 double end_sec = os::elapsedTime(); 5587 double elapsed_ms = (end_sec - start_sec) * 1000.0; 5588 non_young_time_ms += elapsed_ms; 5589 5590 start_sec = os::elapsedTime(); 5591 non_young = false; 5592 } 5593 } else { 5594 if (!cur->is_young()) { 5595 double end_sec = os::elapsedTime(); 5596 double elapsed_ms = (end_sec - start_sec) * 1000.0; 5597 young_time_ms += elapsed_ms; 5598 5599 start_sec = os::elapsedTime(); 5600 non_young = true; 5601 } 5602 } 5603 5604 rs_lengths += cur->rem_set()->occupied_locked(); 5605 5606 HeapRegion* next = cur->next_in_collection_set(); 5607 assert(cur->in_collection_set(), "bad CS"); 5608 cur->set_next_in_collection_set(NULL); 5609 clear_in_cset(cur); 5610 5611 if (cur->is_young()) { 5612 int index = cur->young_index_in_cset(); 5613 assert(index != -1, "invariant"); 5614 assert((uint) index < policy->young_cset_region_length(), "invariant"); 5615 size_t words_survived = surviving_young_words[index]; 5616 cur->record_surv_words_in_group(words_survived); 5617 5618 // At this point the we have 'popped' cur from the collection set 5619 // (linked via next_in_collection_set()) but it is still in the 5620 // young list (linked via next_young_region()). Clear the 5621 // _next_young_region field. 5622 cur->set_next_young_region(NULL); 5623 } else { 5624 int index = cur->young_index_in_cset(); 5625 assert(index == -1, "invariant"); 5626 } 5627 5628 assert( (cur->is_young() && cur->young_index_in_cset() > -1) || 5629 (!cur->is_young() && cur->young_index_in_cset() == -1), 5630 "invariant" ); 5631 5632 if (!cur->evacuation_failed()) { 5633 MemRegion used_mr = cur->used_region(); 5634 5635 // And the region is empty. 5636 assert(!used_mr.is_empty(), "Should not have empty regions in a CS."); 5637 pre_used += cur->used(); 5638 free_region(cur, &local_free_list, false /* par */, true /* locked */); 5639 } else { 5640 cur->uninstall_surv_rate_group(); 5641 if (cur->is_young()) { 5642 cur->set_young_index_in_cset(-1); 5643 } 5644 cur->set_evacuation_failed(false); 5645 // The region is now considered to be old. 5646 cur->set_old(); 5647 // Do some allocation statistics accounting. Regions that failed evacuation 5648 // are always made old, so there is no need to update anything in the young 5649 // gen statistics, but we need to update old gen statistics. 5650 size_t used_words = cur->marked_bytes() / HeapWordSize; 5651 _old_evac_stats.add_failure_used_and_waste(used_words, HeapRegion::GrainWords - used_words); 5652 _old_set.add(cur); 5653 evacuation_info.increment_collectionset_used_after(cur->used()); 5654 } 5655 cur = next; 5656 } 5657 5658 evacuation_info.set_regions_freed(local_free_list.length()); 5659 policy->record_max_rs_lengths(rs_lengths); 5660 policy->cset_regions_freed(); 5661 5662 double end_sec = os::elapsedTime(); 5663 double elapsed_ms = (end_sec - start_sec) * 1000.0; 5664 5665 if (non_young) { 5666 non_young_time_ms += elapsed_ms; 5667 } else { 5668 young_time_ms += elapsed_ms; 5669 } 5670 5671 prepend_to_freelist(&local_free_list); 5672 decrement_summary_bytes(pre_used); 5673 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms); 5674 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms); 5675 } 5676 5677 class G1FreeHumongousRegionClosure : public HeapRegionClosure { 5678 private: 5679 FreeRegionList* _free_region_list; 5680 HeapRegionSet* _proxy_set; 5681 HeapRegionSetCount _humongous_regions_removed; 5682 size_t _freed_bytes; 5683 public: 5684 5685 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) : 5686 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) { 5687 } 5688 5689 virtual bool doHeapRegion(HeapRegion* r) { 5690 if (!r->is_starts_humongous()) { 5691 return false; 5692 } 5693 5694 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 5695 5696 oop obj = (oop)r->bottom(); 5697 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap(); 5698 5699 // The following checks whether the humongous object is live are sufficient. 5700 // The main additional check (in addition to having a reference from the roots 5701 // or the young gen) is whether the humongous object has a remembered set entry. 5702 // 5703 // A humongous object cannot be live if there is no remembered set for it 5704 // because: 5705 // - there can be no references from within humongous starts regions referencing 5706 // the object because we never allocate other objects into them. 5707 // (I.e. there are no intra-region references that may be missed by the 5708 // remembered set) 5709 // - as soon there is a remembered set entry to the humongous starts region 5710 // (i.e. it has "escaped" to an old object) this remembered set entry will stay 5711 // until the end of a concurrent mark. 5712 // 5713 // It is not required to check whether the object has been found dead by marking 5714 // or not, in fact it would prevent reclamation within a concurrent cycle, as 5715 // all objects allocated during that time are considered live. 5716 // SATB marking is even more conservative than the remembered set. 5717 // So if at this point in the collection there is no remembered set entry, 5718 // nobody has a reference to it. 5719 // At the start of collection we flush all refinement logs, and remembered sets 5720 // are completely up-to-date wrt to references to the humongous object. 5721 // 5722 // Other implementation considerations: 5723 // - never consider object arrays at this time because they would pose 5724 // considerable effort for cleaning up the the remembered sets. This is 5725 // required because stale remembered sets might reference locations that 5726 // are currently allocated into. 5727 uint region_idx = r->hrm_index(); 5728 if (!g1h->is_humongous_reclaim_candidate(region_idx) || 5729 !r->rem_set()->is_empty()) { 5730 5731 if (G1TraceEagerReclaimHumongousObjects) { 5732 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", 5733 region_idx, 5734 (size_t)obj->size() * HeapWordSize, 5735 p2i(r->bottom()), 5736 r->rem_set()->occupied(), 5737 r->rem_set()->strong_code_roots_list_length(), 5738 next_bitmap->isMarked(r->bottom()), 5739 g1h->is_humongous_reclaim_candidate(region_idx), 5740 obj->is_typeArray() 5741 ); 5742 } 5743 5744 return false; 5745 } 5746 5747 guarantee(obj->is_typeArray(), 5748 "Only eagerly reclaiming type arrays is supported, but the object " 5749 PTR_FORMAT " is not.", p2i(r->bottom())); 5750 5751 if (G1TraceEagerReclaimHumongousObjects) { 5752 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", 5753 region_idx, 5754 (size_t)obj->size() * HeapWordSize, 5755 p2i(r->bottom()), 5756 r->rem_set()->occupied(), 5757 r->rem_set()->strong_code_roots_list_length(), 5758 next_bitmap->isMarked(r->bottom()), 5759 g1h->is_humongous_reclaim_candidate(region_idx), 5760 obj->is_typeArray() 5761 ); 5762 } 5763 // Need to clear mark bit of the humongous object if already set. 5764 if (next_bitmap->isMarked(r->bottom())) { 5765 next_bitmap->clear(r->bottom()); 5766 } 5767 do { 5768 HeapRegion* next = g1h->next_region_by_index(r); 5769 _freed_bytes += r->used(); 5770 r->set_containing_set(NULL); 5771 _humongous_regions_removed.increment(1u, r->capacity()); 5772 g1h->free_humongous_region(r, _free_region_list, false); 5773 r = next; 5774 } while (r != NULL && r->is_continues_humongous()); 5775 5776 return false; 5777 } 5778 5779 HeapRegionSetCount& humongous_free_count() { 5780 return _humongous_regions_removed; 5781 } 5782 5783 size_t bytes_freed() const { 5784 return _freed_bytes; 5785 } 5786 5787 size_t humongous_reclaimed() const { 5788 return _humongous_regions_removed.length(); 5789 } 5790 }; 5791 5792 void G1CollectedHeap::eagerly_reclaim_humongous_regions() { 5793 assert_at_safepoint(true); 5794 5795 if (!G1EagerReclaimHumongousObjects || 5796 (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) { 5797 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0); 5798 return; 5799 } 5800 5801 double start_time = os::elapsedTime(); 5802 5803 FreeRegionList local_cleanup_list("Local Humongous Cleanup List"); 5804 5805 G1FreeHumongousRegionClosure cl(&local_cleanup_list); 5806 heap_region_iterate(&cl); 5807 5808 HeapRegionSetCount empty_set; 5809 remove_from_old_sets(empty_set, cl.humongous_free_count()); 5810 5811 G1HRPrinter* hrp = hr_printer(); 5812 if (hrp->is_active()) { 5813 FreeRegionListIterator iter(&local_cleanup_list); 5814 while (iter.more_available()) { 5815 HeapRegion* hr = iter.get_next(); 5816 hrp->cleanup(hr); 5817 } 5818 } 5819 5820 prepend_to_freelist(&local_cleanup_list); 5821 decrement_summary_bytes(cl.bytes_freed()); 5822 5823 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0, 5824 cl.humongous_reclaimed()); 5825 } 5826 5827 // This routine is similar to the above but does not record 5828 // any policy statistics or update free lists; we are abandoning 5829 // the current incremental collection set in preparation of a 5830 // full collection. After the full GC we will start to build up 5831 // the incremental collection set again. 5832 // This is only called when we're doing a full collection 5833 // and is immediately followed by the tearing down of the young list. 5834 5835 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) { 5836 HeapRegion* cur = cs_head; 5837 5838 while (cur != NULL) { 5839 HeapRegion* next = cur->next_in_collection_set(); 5840 assert(cur->in_collection_set(), "bad CS"); 5841 cur->set_next_in_collection_set(NULL); 5842 clear_in_cset(cur); 5843 cur->set_young_index_in_cset(-1); 5844 cur = next; 5845 } 5846 } 5847 5848 void G1CollectedHeap::set_free_regions_coming() { 5849 if (G1ConcRegionFreeingVerbose) { 5850 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " 5851 "setting free regions coming"); 5852 } 5853 5854 assert(!free_regions_coming(), "pre-condition"); 5855 _free_regions_coming = true; 5856 } 5857 5858 void G1CollectedHeap::reset_free_regions_coming() { 5859 assert(free_regions_coming(), "pre-condition"); 5860 5861 { 5862 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 5863 _free_regions_coming = false; 5864 SecondaryFreeList_lock->notify_all(); 5865 } 5866 5867 if (G1ConcRegionFreeingVerbose) { 5868 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " 5869 "reset free regions coming"); 5870 } 5871 } 5872 5873 void G1CollectedHeap::wait_while_free_regions_coming() { 5874 // Most of the time we won't have to wait, so let's do a quick test 5875 // first before we take the lock. 5876 if (!free_regions_coming()) { 5877 return; 5878 } 5879 5880 if (G1ConcRegionFreeingVerbose) { 5881 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " 5882 "waiting for free regions"); 5883 } 5884 5885 { 5886 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 5887 while (free_regions_coming()) { 5888 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 5889 } 5890 } 5891 5892 if (G1ConcRegionFreeingVerbose) { 5893 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " 5894 "done waiting for free regions"); 5895 } 5896 } 5897 5898 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) { 5899 return _allocator->is_retained_old_region(hr); 5900 } 5901 5902 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 5903 _young_list->push_region(hr); 5904 } 5905 5906 class NoYoungRegionsClosure: public HeapRegionClosure { 5907 private: 5908 bool _success; 5909 public: 5910 NoYoungRegionsClosure() : _success(true) { } 5911 bool doHeapRegion(HeapRegion* r) { 5912 if (r->is_young()) { 5913 gclog_or_tty->print_cr("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young", 5914 p2i(r->bottom()), p2i(r->end())); 5915 _success = false; 5916 } 5917 return false; 5918 } 5919 bool success() { return _success; } 5920 }; 5921 5922 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) { 5923 bool ret = _young_list->check_list_empty(check_sample); 5924 5925 if (check_heap) { 5926 NoYoungRegionsClosure closure; 5927 heap_region_iterate(&closure); 5928 ret = ret && closure.success(); 5929 } 5930 5931 return ret; 5932 } 5933 5934 class TearDownRegionSetsClosure : public HeapRegionClosure { 5935 private: 5936 HeapRegionSet *_old_set; 5937 5938 public: 5939 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { } 5940 5941 bool doHeapRegion(HeapRegion* r) { 5942 if (r->is_old()) { 5943 _old_set->remove(r); 5944 } else { 5945 // We ignore free regions, we'll empty the free list afterwards. 5946 // We ignore young regions, we'll empty the young list afterwards. 5947 // We ignore humongous regions, we're not tearing down the 5948 // humongous regions set. 5949 assert(r->is_free() || r->is_young() || r->is_humongous(), 5950 "it cannot be another type"); 5951 } 5952 return false; 5953 } 5954 5955 ~TearDownRegionSetsClosure() { 5956 assert(_old_set->is_empty(), "post-condition"); 5957 } 5958 }; 5959 5960 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) { 5961 assert_at_safepoint(true /* should_be_vm_thread */); 5962 5963 if (!free_list_only) { 5964 TearDownRegionSetsClosure cl(&_old_set); 5965 heap_region_iterate(&cl); 5966 5967 // Note that emptying the _young_list is postponed and instead done as 5968 // the first step when rebuilding the regions sets again. The reason for 5969 // this is that during a full GC string deduplication needs to know if 5970 // a collected region was young or old when the full GC was initiated. 5971 } 5972 _hrm.remove_all_free_regions(); 5973 } 5974 5975 void G1CollectedHeap::increase_used(size_t bytes) { 5976 _summary_bytes_used += bytes; 5977 } 5978 5979 void G1CollectedHeap::decrease_used(size_t bytes) { 5980 assert(_summary_bytes_used >= bytes, 5981 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT, 5982 _summary_bytes_used, bytes); 5983 _summary_bytes_used -= bytes; 5984 } 5985 5986 void G1CollectedHeap::set_used(size_t bytes) { 5987 _summary_bytes_used = bytes; 5988 } 5989 5990 class RebuildRegionSetsClosure : public HeapRegionClosure { 5991 private: 5992 bool _free_list_only; 5993 HeapRegionSet* _old_set; 5994 HeapRegionManager* _hrm; 5995 size_t _total_used; 5996 5997 public: 5998 RebuildRegionSetsClosure(bool free_list_only, 5999 HeapRegionSet* old_set, HeapRegionManager* hrm) : 6000 _free_list_only(free_list_only), 6001 _old_set(old_set), _hrm(hrm), _total_used(0) { 6002 assert(_hrm->num_free_regions() == 0, "pre-condition"); 6003 if (!free_list_only) { 6004 assert(_old_set->is_empty(), "pre-condition"); 6005 } 6006 } 6007 6008 bool doHeapRegion(HeapRegion* r) { 6009 if (r->is_empty()) { 6010 // Add free regions to the free list 6011 r->set_free(); 6012 r->set_allocation_context(AllocationContext::system()); 6013 _hrm->insert_into_free_list(r); 6014 } else if (!_free_list_only) { 6015 assert(!r->is_young(), "we should not come across young regions"); 6016 6017 if (r->is_humongous()) { 6018 // We ignore humongous regions. We left the humongous set unchanged. 6019 } else { 6020 // Objects that were compacted would have ended up on regions 6021 // that were previously old or free. Archive regions (which are 6022 // old) will not have been touched. 6023 assert(r->is_free() || r->is_old(), "invariant"); 6024 // We now consider them old, so register as such. Leave 6025 // archive regions set that way, however, while still adding 6026 // them to the old set. 6027 if (!r->is_archive()) { 6028 r->set_old(); 6029 } 6030 _old_set->add(r); 6031 } 6032 _total_used += r->used(); 6033 } 6034 6035 return false; 6036 } 6037 6038 size_t total_used() { 6039 return _total_used; 6040 } 6041 }; 6042 6043 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { 6044 assert_at_safepoint(true /* should_be_vm_thread */); 6045 6046 if (!free_list_only) { 6047 _young_list->empty_list(); 6048 } 6049 6050 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm); 6051 heap_region_iterate(&cl); 6052 6053 if (!free_list_only) { 6054 set_used(cl.total_used()); 6055 if (_archive_allocator != NULL) { 6056 _archive_allocator->clear_used(); 6057 } 6058 } 6059 assert(used_unlocked() == recalculate_used(), 6060 "inconsistent used_unlocked(), " 6061 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT, 6062 used_unlocked(), recalculate_used()); 6063 } 6064 6065 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) { 6066 _refine_cte_cl->set_concurrent(concurrent); 6067 } 6068 6069 bool G1CollectedHeap::is_in_closed_subset(const void* p) const { 6070 HeapRegion* hr = heap_region_containing(p); 6071 return hr->is_in(p); 6072 } 6073 6074 // Methods for the mutator alloc region 6075 6076 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 6077 bool force) { 6078 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6079 assert(!force || g1_policy()->can_expand_young_list(), 6080 "if force is true we should be able to expand the young list"); 6081 bool young_list_full = g1_policy()->is_young_list_full(); 6082 if (force || !young_list_full) { 6083 HeapRegion* new_alloc_region = new_region(word_size, 6084 false /* is_old */, 6085 false /* do_expand */); 6086 if (new_alloc_region != NULL) { 6087 set_region_short_lived_locked(new_alloc_region); 6088 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full); 6089 check_bitmaps("Mutator Region Allocation", new_alloc_region); 6090 return new_alloc_region; 6091 } 6092 } 6093 return NULL; 6094 } 6095 6096 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 6097 size_t allocated_bytes) { 6098 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6099 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden"); 6100 6101 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region); 6102 increase_used(allocated_bytes); 6103 _hr_printer.retire(alloc_region); 6104 // We update the eden sizes here, when the region is retired, 6105 // instead of when it's allocated, since this is the point that its 6106 // used space has been recored in _summary_bytes_used. 6107 g1mm()->update_eden_size(); 6108 } 6109 6110 // Methods for the GC alloc regions 6111 6112 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, 6113 uint count, 6114 InCSetState dest) { 6115 assert(FreeList_lock->owned_by_self(), "pre-condition"); 6116 6117 if (count < g1_policy()->max_regions(dest)) { 6118 const bool is_survivor = (dest.is_young()); 6119 HeapRegion* new_alloc_region = new_region(word_size, 6120 !is_survivor, 6121 true /* do_expand */); 6122 if (new_alloc_region != NULL) { 6123 // We really only need to do this for old regions given that we 6124 // should never scan survivors. But it doesn't hurt to do it 6125 // for survivors too. 6126 new_alloc_region->record_timestamp(); 6127 if (is_survivor) { 6128 new_alloc_region->set_survivor(); 6129 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor); 6130 check_bitmaps("Survivor Region Allocation", new_alloc_region); 6131 } else { 6132 new_alloc_region->set_old(); 6133 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old); 6134 check_bitmaps("Old Region Allocation", new_alloc_region); 6135 } 6136 bool during_im = collector_state()->during_initial_mark_pause(); 6137 new_alloc_region->note_start_of_copying(during_im); 6138 return new_alloc_region; 6139 } 6140 } 6141 return NULL; 6142 } 6143 6144 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 6145 size_t allocated_bytes, 6146 InCSetState dest) { 6147 bool during_im = collector_state()->during_initial_mark_pause(); 6148 alloc_region->note_end_of_copying(during_im); 6149 g1_policy()->record_bytes_copied_during_gc(allocated_bytes); 6150 if (dest.is_young()) { 6151 young_list()->add_survivor_region(alloc_region); 6152 } else { 6153 _old_set.add(alloc_region); 6154 } 6155 _hr_printer.retire(alloc_region); 6156 } 6157 6158 HeapRegion* G1CollectedHeap::alloc_highest_free_region() { 6159 bool expanded = false; 6160 uint index = _hrm.find_highest_free(&expanded); 6161 6162 if (index != G1_NO_HRM_INDEX) { 6163 if (expanded) { 6164 ergo_verbose1(ErgoHeapSizing, 6165 "attempt heap expansion", 6166 ergo_format_reason("requested address range outside heap bounds") 6167 ergo_format_byte("region size"), 6168 HeapRegion::GrainWords * HeapWordSize); 6169 } 6170 _hrm.allocate_free_regions_starting_at(index, 1); 6171 return region_at(index); 6172 } 6173 return NULL; 6174 } 6175 6176 // Heap region set verification 6177 6178 class VerifyRegionListsClosure : public HeapRegionClosure { 6179 private: 6180 HeapRegionSet* _old_set; 6181 HeapRegionSet* _humongous_set; 6182 HeapRegionManager* _hrm; 6183 6184 public: 6185 HeapRegionSetCount _old_count; 6186 HeapRegionSetCount _humongous_count; 6187 HeapRegionSetCount _free_count; 6188 6189 VerifyRegionListsClosure(HeapRegionSet* old_set, 6190 HeapRegionSet* humongous_set, 6191 HeapRegionManager* hrm) : 6192 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm), 6193 _old_count(), _humongous_count(), _free_count(){ } 6194 6195 bool doHeapRegion(HeapRegion* hr) { 6196 if (hr->is_young()) { 6197 // TODO 6198 } else if (hr->is_humongous()) { 6199 assert(hr->containing_set() == _humongous_set, "Heap region %u is humongous but not in humongous set.", hr->hrm_index()); 6200 _humongous_count.increment(1u, hr->capacity()); 6201 } else if (hr->is_empty()) { 6202 assert(_hrm->is_free(hr), "Heap region %u is empty but not on the free list.", hr->hrm_index()); 6203 _free_count.increment(1u, hr->capacity()); 6204 } else if (hr->is_old()) { 6205 assert(hr->containing_set() == _old_set, "Heap region %u is old but not in the old set.", hr->hrm_index()); 6206 _old_count.increment(1u, hr->capacity()); 6207 } else { 6208 // There are no other valid region types. Check for one invalid 6209 // one we can identify: pinned without old or humongous set. 6210 assert(!hr->is_pinned(), "Heap region %u is pinned but not old (archive) or humongous.", hr->hrm_index()); 6211 ShouldNotReachHere(); 6212 } 6213 return false; 6214 } 6215 6216 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) { 6217 guarantee(old_set->length() == _old_count.length(), "Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()); 6218 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), "Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6219 old_set->total_capacity_bytes(), _old_count.capacity()); 6220 6221 guarantee(humongous_set->length() == _humongous_count.length(), "Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()); 6222 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), "Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6223 humongous_set->total_capacity_bytes(), _humongous_count.capacity()); 6224 6225 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()); 6226 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), "Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6227 free_list->total_capacity_bytes(), _free_count.capacity()); 6228 } 6229 }; 6230 6231 void G1CollectedHeap::verify_region_sets() { 6232 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6233 6234 // First, check the explicit lists. 6235 _hrm.verify(); 6236 { 6237 // Given that a concurrent operation might be adding regions to 6238 // the secondary free list we have to take the lock before 6239 // verifying it. 6240 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6241 _secondary_free_list.verify_list(); 6242 } 6243 6244 // If a concurrent region freeing operation is in progress it will 6245 // be difficult to correctly attributed any free regions we come 6246 // across to the correct free list given that they might belong to 6247 // one of several (free_list, secondary_free_list, any local lists, 6248 // etc.). So, if that's the case we will skip the rest of the 6249 // verification operation. Alternatively, waiting for the concurrent 6250 // operation to complete will have a non-trivial effect on the GC's 6251 // operation (no concurrent operation will last longer than the 6252 // interval between two calls to verification) and it might hide 6253 // any issues that we would like to catch during testing. 6254 if (free_regions_coming()) { 6255 return; 6256 } 6257 6258 // Make sure we append the secondary_free_list on the free_list so 6259 // that all free regions we will come across can be safely 6260 // attributed to the free_list. 6261 append_secondary_free_list_if_not_empty_with_lock(); 6262 6263 // Finally, make sure that the region accounting in the lists is 6264 // consistent with what we see in the heap. 6265 6266 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm); 6267 heap_region_iterate(&cl); 6268 cl.verify_counts(&_old_set, &_humongous_set, &_hrm); 6269 } 6270 6271 // Optimized nmethod scanning 6272 6273 class RegisterNMethodOopClosure: public OopClosure { 6274 G1CollectedHeap* _g1h; 6275 nmethod* _nm; 6276 6277 template <class T> void do_oop_work(T* p) { 6278 T heap_oop = oopDesc::load_heap_oop(p); 6279 if (!oopDesc::is_null(heap_oop)) { 6280 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 6281 HeapRegion* hr = _g1h->heap_region_containing(obj); 6282 assert(!hr->is_continues_humongous(), 6283 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 6284 " starting at " HR_FORMAT, 6285 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 6286 6287 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries. 6288 hr->add_strong_code_root_locked(_nm); 6289 } 6290 } 6291 6292 public: 6293 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 6294 _g1h(g1h), _nm(nm) {} 6295 6296 void do_oop(oop* p) { do_oop_work(p); } 6297 void do_oop(narrowOop* p) { do_oop_work(p); } 6298 }; 6299 6300 class UnregisterNMethodOopClosure: public OopClosure { 6301 G1CollectedHeap* _g1h; 6302 nmethod* _nm; 6303 6304 template <class T> void do_oop_work(T* p) { 6305 T heap_oop = oopDesc::load_heap_oop(p); 6306 if (!oopDesc::is_null(heap_oop)) { 6307 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 6308 HeapRegion* hr = _g1h->heap_region_containing(obj); 6309 assert(!hr->is_continues_humongous(), 6310 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 6311 " starting at " HR_FORMAT, 6312 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 6313 6314 hr->remove_strong_code_root(_nm); 6315 } 6316 } 6317 6318 public: 6319 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 6320 _g1h(g1h), _nm(nm) {} 6321 6322 void do_oop(oop* p) { do_oop_work(p); } 6323 void do_oop(narrowOop* p) { do_oop_work(p); } 6324 }; 6325 6326 void G1CollectedHeap::register_nmethod(nmethod* nm) { 6327 CollectedHeap::register_nmethod(nm); 6328 6329 guarantee(nm != NULL, "sanity"); 6330 RegisterNMethodOopClosure reg_cl(this, nm); 6331 nm->oops_do(®_cl); 6332 } 6333 6334 void G1CollectedHeap::unregister_nmethod(nmethod* nm) { 6335 CollectedHeap::unregister_nmethod(nm); 6336 6337 guarantee(nm != NULL, "sanity"); 6338 UnregisterNMethodOopClosure reg_cl(this, nm); 6339 nm->oops_do(®_cl, true); 6340 } 6341 6342 void G1CollectedHeap::purge_code_root_memory() { 6343 double purge_start = os::elapsedTime(); 6344 G1CodeRootSet::purge(); 6345 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0; 6346 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms); 6347 } 6348 6349 class RebuildStrongCodeRootClosure: public CodeBlobClosure { 6350 G1CollectedHeap* _g1h; 6351 6352 public: 6353 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) : 6354 _g1h(g1h) {} 6355 6356 void do_code_blob(CodeBlob* cb) { 6357 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL; 6358 if (nm == NULL) { 6359 return; 6360 } 6361 6362 if (ScavengeRootsInCode) { 6363 _g1h->register_nmethod(nm); 6364 } 6365 } 6366 }; 6367 6368 void G1CollectedHeap::rebuild_strong_code_roots() { 6369 RebuildStrongCodeRootClosure blob_cl(this); 6370 CodeCache::blobs_do(&blob_cl); 6371 }