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