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 #if !defined(__clang_major__) && defined(__GNUC__) 26 // FIXME, formats have issues. Disable this macro definition, compile, and study warnings for more information. 27 #define ATTRIBUTE_PRINTF(x,y) 28 #endif 29 30 #include "precompiled.hpp" 31 #include "classfile/metadataOnStackMark.hpp" 32 #include "classfile/stringTable.hpp" 33 #include "code/codeCache.hpp" 34 #include "code/icBuffer.hpp" 35 #include "gc_implementation/g1/bufferingOopClosure.hpp" 36 #include "gc_implementation/g1/concurrentG1Refine.hpp" 37 #include "gc_implementation/g1/concurrentG1RefineThread.hpp" 38 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp" 39 #include "gc_implementation/g1/g1AllocRegion.inline.hpp" 40 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp" 41 #include "gc_implementation/g1/g1CollectorPolicy.hpp" 42 #include "gc_implementation/g1/g1ErgoVerbose.hpp" 43 #include "gc_implementation/g1/g1EvacFailure.hpp" 44 #include "gc_implementation/g1/g1GCPhaseTimes.hpp" 45 #include "gc_implementation/g1/g1Log.hpp" 46 #include "gc_implementation/g1/g1MarkSweep.hpp" 47 #include "gc_implementation/g1/g1OopClosures.inline.hpp" 48 #include "gc_implementation/g1/g1ParScanThreadState.inline.hpp" 49 #include "gc_implementation/g1/g1RegionToSpaceMapper.hpp" 50 #include "gc_implementation/g1/g1RemSet.inline.hpp" 51 #include "gc_implementation/g1/g1StringDedup.hpp" 52 #include "gc_implementation/g1/g1YCTypes.hpp" 53 #include "gc_implementation/g1/heapRegion.inline.hpp" 54 #include "gc_implementation/g1/heapRegionRemSet.hpp" 55 #include "gc_implementation/g1/heapRegionSet.inline.hpp" 56 #include "gc_implementation/g1/vm_operations_g1.hpp" 57 #include "gc_implementation/shared/gcHeapSummary.hpp" 58 #include "gc_implementation/shared/gcTimer.hpp" 59 #include "gc_implementation/shared/gcTrace.hpp" 60 #include "gc_implementation/shared/gcTraceTime.hpp" 61 #include "gc_implementation/shared/isGCActiveMark.hpp" 62 #include "memory/allocation.hpp" 63 #include "memory/gcLocker.inline.hpp" 64 #include "memory/generationSpec.hpp" 65 #include "memory/iterator.hpp" 66 #include "memory/referenceProcessor.hpp" 67 #include "oops/oop.inline.hpp" 68 #include "oops/oop.pcgc.inline.hpp" 69 #include "runtime/atomic.inline.hpp" 70 #include "runtime/orderAccess.inline.hpp" 71 #include "runtime/vmThread.hpp" 72 #include "utilities/globalDefinitions.hpp" 73 74 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0; 75 76 // turn it on so that the contents of the young list (scan-only / 77 // to-be-collected) are printed at "strategic" points before / during 78 // / after the collection --- this is useful for debugging 79 #define YOUNG_LIST_VERBOSE 0 80 // CURRENT STATUS 81 // This file is under construction. Search for "FIXME". 82 83 // INVARIANTS/NOTES 84 // 85 // All allocation activity covered by the G1CollectedHeap interface is 86 // serialized by acquiring the HeapLock. This happens in mem_allocate 87 // and allocate_new_tlab, which are the "entry" points to the 88 // allocation code from the rest of the JVM. (Note that this does not 89 // apply to TLAB allocation, which is not part of this interface: it 90 // is done by clients of this interface.) 91 92 // Notes on implementation of parallelism in different tasks. 93 // 94 // G1ParVerifyTask uses heap_region_par_iterate() for parallelism. 95 // The number of GC workers is passed to heap_region_par_iterate(). 96 // It does use run_task() which sets _n_workers in the task. 97 // G1ParTask executes g1_process_roots() -> 98 // SharedHeap::process_roots() which calls eventually to 99 // CardTableModRefBS::par_non_clean_card_iterate_work() which uses 100 // SequentialSubTasksDone. SharedHeap::process_roots() also 101 // directly uses SubTasksDone (_process_strong_tasks field in SharedHeap). 102 // 103 104 // Local to this file. 105 106 class RefineCardTableEntryClosure: public CardTableEntryClosure { 107 bool _concurrent; 108 public: 109 RefineCardTableEntryClosure() : _concurrent(true) { } 110 111 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 112 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false); 113 // This path is executed by the concurrent refine or mutator threads, 114 // concurrently, and so we do not care if card_ptr contains references 115 // that point into the collection set. 116 assert(!oops_into_cset, "should be"); 117 118 if (_concurrent && SuspendibleThreadSet::should_yield()) { 119 // Caller will actually yield. 120 return false; 121 } 122 // Otherwise, we finished successfully; return true. 123 return true; 124 } 125 126 void set_concurrent(bool b) { _concurrent = b; } 127 }; 128 129 130 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure { 131 private: 132 size_t _num_processed; 133 134 public: 135 RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { } 136 137 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 138 *card_ptr = CardTableModRefBS::dirty_card_val(); 139 _num_processed++; 140 return true; 141 } 142 143 size_t num_processed() const { return _num_processed; } 144 }; 145 146 YoungList::YoungList(G1CollectedHeap* g1h) : 147 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0), 148 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) { 149 guarantee(check_list_empty(false), "just making sure..."); 150 } 151 152 void YoungList::push_region(HeapRegion *hr) { 153 assert(!hr->is_young(), "should not already be young"); 154 assert(hr->get_next_young_region() == NULL, "cause it should!"); 155 156 hr->set_next_young_region(_head); 157 _head = hr; 158 159 _g1h->g1_policy()->set_region_eden(hr, (int) _length); 160 ++_length; 161 } 162 163 void YoungList::add_survivor_region(HeapRegion* hr) { 164 assert(hr->is_survivor(), "should be flagged as survivor region"); 165 assert(hr->get_next_young_region() == NULL, "cause it should!"); 166 167 hr->set_next_young_region(_survivor_head); 168 if (_survivor_head == NULL) { 169 _survivor_tail = hr; 170 } 171 _survivor_head = hr; 172 ++_survivor_length; 173 } 174 175 void YoungList::empty_list(HeapRegion* list) { 176 while (list != NULL) { 177 HeapRegion* next = list->get_next_young_region(); 178 list->set_next_young_region(NULL); 179 list->uninstall_surv_rate_group(); 180 // This is called before a Full GC and all the non-empty / 181 // non-humongous regions at the end of the Full GC will end up as 182 // old anyway. 183 list->set_old(); 184 list = next; 185 } 186 } 187 188 void YoungList::empty_list() { 189 assert(check_list_well_formed(), "young list should be well formed"); 190 191 empty_list(_head); 192 _head = NULL; 193 _length = 0; 194 195 empty_list(_survivor_head); 196 _survivor_head = NULL; 197 _survivor_tail = NULL; 198 _survivor_length = 0; 199 200 _last_sampled_rs_lengths = 0; 201 202 assert(check_list_empty(false), "just making sure..."); 203 } 204 205 bool YoungList::check_list_well_formed() { 206 bool ret = true; 207 208 uint length = 0; 209 HeapRegion* curr = _head; 210 HeapRegion* last = NULL; 211 while (curr != NULL) { 212 if (!curr->is_young()) { 213 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" " 214 "incorrectly tagged (y: %d, surv: %d)", 215 curr->bottom(), curr->end(), 216 curr->is_young(), curr->is_survivor()); 217 ret = false; 218 } 219 ++length; 220 last = curr; 221 curr = curr->get_next_young_region(); 222 } 223 ret = ret && (length == _length); 224 225 if (!ret) { 226 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!"); 227 gclog_or_tty->print_cr("### list has %u entries, _length is %u", 228 length, _length); 229 } 230 231 return ret; 232 } 233 234 bool YoungList::check_list_empty(bool check_sample) { 235 bool ret = true; 236 237 if (_length != 0) { 238 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u", 239 _length); 240 ret = false; 241 } 242 if (check_sample && _last_sampled_rs_lengths != 0) { 243 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths"); 244 ret = false; 245 } 246 if (_head != NULL) { 247 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head"); 248 ret = false; 249 } 250 if (!ret) { 251 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty"); 252 } 253 254 return ret; 255 } 256 257 void 258 YoungList::rs_length_sampling_init() { 259 _sampled_rs_lengths = 0; 260 _curr = _head; 261 } 262 263 bool 264 YoungList::rs_length_sampling_more() { 265 return _curr != NULL; 266 } 267 268 void 269 YoungList::rs_length_sampling_next() { 270 assert( _curr != NULL, "invariant" ); 271 size_t rs_length = _curr->rem_set()->occupied(); 272 273 _sampled_rs_lengths += rs_length; 274 275 // The current region may not yet have been added to the 276 // incremental collection set (it gets added when it is 277 // retired as the current allocation region). 278 if (_curr->in_collection_set()) { 279 // Update the collection set policy information for this region 280 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length); 281 } 282 283 _curr = _curr->get_next_young_region(); 284 if (_curr == NULL) { 285 _last_sampled_rs_lengths = _sampled_rs_lengths; 286 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths); 287 } 288 } 289 290 void 291 YoungList::reset_auxilary_lists() { 292 guarantee( is_empty(), "young list should be empty" ); 293 assert(check_list_well_formed(), "young list should be well formed"); 294 295 // Add survivor regions to SurvRateGroup. 296 _g1h->g1_policy()->note_start_adding_survivor_regions(); 297 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */); 298 299 int young_index_in_cset = 0; 300 for (HeapRegion* curr = _survivor_head; 301 curr != NULL; 302 curr = curr->get_next_young_region()) { 303 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset); 304 305 // The region is a non-empty survivor so let's add it to 306 // the incremental collection set for the next evacuation 307 // pause. 308 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr); 309 young_index_in_cset += 1; 310 } 311 assert((uint) young_index_in_cset == _survivor_length, "post-condition"); 312 _g1h->g1_policy()->note_stop_adding_survivor_regions(); 313 314 _head = _survivor_head; 315 _length = _survivor_length; 316 if (_survivor_head != NULL) { 317 assert(_survivor_tail != NULL, "cause it shouldn't be"); 318 assert(_survivor_length > 0, "invariant"); 319 _survivor_tail->set_next_young_region(NULL); 320 } 321 322 // Don't clear the survivor list handles until the start of 323 // the next evacuation pause - we need it in order to re-tag 324 // the survivor regions from this evacuation pause as 'young' 325 // at the start of the next. 326 327 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */); 328 329 assert(check_list_well_formed(), "young list should be well formed"); 330 } 331 332 void YoungList::print() { 333 HeapRegion* lists[] = {_head, _survivor_head}; 334 const char* names[] = {"YOUNG", "SURVIVOR"}; 335 336 for (uint list = 0; list < ARRAY_SIZE(lists); ++list) { 337 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]); 338 HeapRegion *curr = lists[list]; 339 if (curr == NULL) 340 gclog_or_tty->print_cr(" empty"); 341 while (curr != NULL) { 342 gclog_or_tty->print_cr(" "HR_FORMAT", P: "PTR_FORMAT ", N: "PTR_FORMAT", age: %4d", 343 HR_FORMAT_PARAMS(curr), 344 curr->prev_top_at_mark_start(), 345 curr->next_top_at_mark_start(), 346 curr->age_in_surv_rate_group_cond()); 347 curr = curr->get_next_young_region(); 348 } 349 } 350 351 gclog_or_tty->cr(); 352 } 353 354 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) { 355 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions); 356 } 357 358 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) { 359 // The from card cache is not the memory that is actually committed. So we cannot 360 // take advantage of the zero_filled parameter. 361 reset_from_card_cache(start_idx, num_regions); 362 } 363 364 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr) 365 { 366 // Claim the right to put the region on the dirty cards region list 367 // by installing a self pointer. 368 HeapRegion* next = hr->get_next_dirty_cards_region(); 369 if (next == NULL) { 370 HeapRegion* res = (HeapRegion*) 371 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(), 372 NULL); 373 if (res == NULL) { 374 HeapRegion* head; 375 do { 376 // Put the region to the dirty cards region list. 377 head = _dirty_cards_region_list; 378 next = (HeapRegion*) 379 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head); 380 if (next == head) { 381 assert(hr->get_next_dirty_cards_region() == hr, 382 "hr->get_next_dirty_cards_region() != hr"); 383 if (next == NULL) { 384 // The last region in the list points to itself. 385 hr->set_next_dirty_cards_region(hr); 386 } else { 387 hr->set_next_dirty_cards_region(next); 388 } 389 } 390 } while (next != head); 391 } 392 } 393 } 394 395 HeapRegion* G1CollectedHeap::pop_dirty_cards_region() 396 { 397 HeapRegion* head; 398 HeapRegion* hr; 399 do { 400 head = _dirty_cards_region_list; 401 if (head == NULL) { 402 return NULL; 403 } 404 HeapRegion* new_head = head->get_next_dirty_cards_region(); 405 if (head == new_head) { 406 // The last region. 407 new_head = NULL; 408 } 409 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list, 410 head); 411 } while (hr != head); 412 assert(hr != NULL, "invariant"); 413 hr->set_next_dirty_cards_region(NULL); 414 return hr; 415 } 416 417 #ifdef ASSERT 418 // A region is added to the collection set as it is retired 419 // so an address p can point to a region which will be in the 420 // collection set but has not yet been retired. This method 421 // therefore is only accurate during a GC pause after all 422 // regions have been retired. It is used for debugging 423 // to check if an nmethod has references to objects that can 424 // be move during a partial collection. Though it can be 425 // inaccurate, it is sufficient for G1 because the conservative 426 // implementation of is_scavengable() for G1 will indicate that 427 // all nmethods must be scanned during a partial collection. 428 bool G1CollectedHeap::is_in_partial_collection(const void* p) { 429 if (p == NULL) { 430 return false; 431 } 432 return heap_region_containing(p)->in_collection_set(); 433 } 434 #endif 435 436 // Returns true if the reference points to an object that 437 // can move in an incremental collection. 438 bool G1CollectedHeap::is_scavengable(const void* p) { 439 HeapRegion* hr = heap_region_containing(p); 440 return !hr->is_humongous(); 441 } 442 443 // Private class members. 444 445 G1CollectedHeap* G1CollectedHeap::_g1h; 446 447 // Private methods. 448 449 HeapRegion* 450 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) { 451 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 452 while (!_secondary_free_list.is_empty() || free_regions_coming()) { 453 if (!_secondary_free_list.is_empty()) { 454 if (G1ConcRegionFreeingVerbose) { 455 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 456 "secondary_free_list has %u entries", 457 _secondary_free_list.length()); 458 } 459 // It looks as if there are free regions available on the 460 // secondary_free_list. Let's move them to the free_list and try 461 // again to allocate from it. 462 append_secondary_free_list(); 463 464 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not " 465 "empty we should have moved at least one entry to the free_list"); 466 HeapRegion* res = _hrm.allocate_free_region(is_old); 467 if (G1ConcRegionFreeingVerbose) { 468 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 469 "allocated "HR_FORMAT" from secondary_free_list", 470 HR_FORMAT_PARAMS(res)); 471 } 472 return res; 473 } 474 475 // Wait here until we get notified either when (a) there are no 476 // more free regions coming or (b) some regions have been moved on 477 // the secondary_free_list. 478 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 479 } 480 481 if (G1ConcRegionFreeingVerbose) { 482 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 483 "could not allocate from secondary_free_list"); 484 } 485 return NULL; 486 } 487 488 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) { 489 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords, 490 "the only time we use this to allocate a humongous region is " 491 "when we are allocating a single humongous region"); 492 493 HeapRegion* res; 494 if (G1StressConcRegionFreeing) { 495 if (!_secondary_free_list.is_empty()) { 496 if (G1ConcRegionFreeingVerbose) { 497 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 498 "forced to look at the secondary_free_list"); 499 } 500 res = new_region_try_secondary_free_list(is_old); 501 if (res != NULL) { 502 return res; 503 } 504 } 505 } 506 507 res = _hrm.allocate_free_region(is_old); 508 509 if (res == NULL) { 510 if (G1ConcRegionFreeingVerbose) { 511 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 512 "res == NULL, trying the secondary_free_list"); 513 } 514 res = new_region_try_secondary_free_list(is_old); 515 } 516 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) { 517 // Currently, only attempts to allocate GC alloc regions set 518 // do_expand to true. So, we should only reach here during a 519 // safepoint. If this assumption changes we might have to 520 // reconsider the use of _expand_heap_after_alloc_failure. 521 assert(SafepointSynchronize::is_at_safepoint(), "invariant"); 522 523 ergo_verbose1(ErgoHeapSizing, 524 "attempt heap expansion", 525 ergo_format_reason("region allocation request failed") 526 ergo_format_byte("allocation request"), 527 word_size * HeapWordSize); 528 if (expand(word_size * HeapWordSize)) { 529 // Given that expand() succeeded in expanding the heap, and we 530 // always expand the heap by an amount aligned to the heap 531 // region size, the free list should in theory not be empty. 532 // In either case allocate_free_region() will check for NULL. 533 res = _hrm.allocate_free_region(is_old); 534 } else { 535 _expand_heap_after_alloc_failure = false; 536 } 537 } 538 return res; 539 } 540 541 HeapWord* 542 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first, 543 uint num_regions, 544 size_t word_size, 545 AllocationContext_t context) { 546 assert(first != G1_NO_HRM_INDEX, "pre-condition"); 547 assert(is_humongous(word_size), "word_size should be humongous"); 548 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition"); 549 550 // Index of last region in the series + 1. 551 uint last = first + num_regions; 552 553 // We need to initialize the region(s) we just discovered. This is 554 // a bit tricky given that it can happen concurrently with 555 // refinement threads refining cards on these regions and 556 // potentially wanting to refine the BOT as they are scanning 557 // those cards (this can happen shortly after a cleanup; see CR 558 // 6991377). So we have to set up the region(s) carefully and in 559 // a specific order. 560 561 // The word size sum of all the regions we will allocate. 562 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords; 563 assert(word_size <= word_size_sum, "sanity"); 564 565 // This will be the "starts humongous" region. 566 HeapRegion* first_hr = region_at(first); 567 // The header of the new object will be placed at the bottom of 568 // the first region. 569 HeapWord* new_obj = first_hr->bottom(); 570 // This will be the new end of the first region in the series that 571 // should also match the end of the last region in the series. 572 HeapWord* new_end = new_obj + word_size_sum; 573 // This will be the new top of the first region that will reflect 574 // this allocation. 575 HeapWord* new_top = new_obj + word_size; 576 577 // First, we need to zero the header of the space that we will be 578 // allocating. When we update top further down, some refinement 579 // threads might try to scan the region. By zeroing the header we 580 // ensure that any thread that will try to scan the region will 581 // come across the zero klass word and bail out. 582 // 583 // NOTE: It would not have been correct to have used 584 // CollectedHeap::fill_with_object() and make the space look like 585 // an int array. The thread that is doing the allocation will 586 // later update the object header to a potentially different array 587 // type and, for a very short period of time, the klass and length 588 // fields will be inconsistent. This could cause a refinement 589 // thread to calculate the object size incorrectly. 590 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0); 591 592 // We will set up the first region as "starts humongous". This 593 // will also update the BOT covering all the regions to reflect 594 // that there is a single object that starts at the bottom of the 595 // first region. 596 first_hr->set_starts_humongous(new_top, new_end); 597 first_hr->set_allocation_context(context); 598 // Then, if there are any, we will set up the "continues 599 // humongous" regions. 600 HeapRegion* hr = NULL; 601 for (uint i = first + 1; i < last; ++i) { 602 hr = region_at(i); 603 hr->set_continues_humongous(first_hr); 604 hr->set_allocation_context(context); 605 } 606 // If we have "continues humongous" regions (hr != NULL), then the 607 // end of the last one should match new_end. 608 assert(hr == NULL || hr->end() == new_end, "sanity"); 609 610 // Up to this point no concurrent thread would have been able to 611 // do any scanning on any region in this series. All the top 612 // fields still point to bottom, so the intersection between 613 // [bottom,top] and [card_start,card_end] will be empty. Before we 614 // update the top fields, we'll do a storestore to make sure that 615 // no thread sees the update to top before the zeroing of the 616 // object header and the BOT initialization. 617 OrderAccess::storestore(); 618 619 // Now that the BOT and the object header have been initialized, 620 // we can update top of the "starts humongous" region. 621 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(), 622 "new_top should be in this region"); 623 first_hr->set_top(new_top); 624 if (_hr_printer.is_active()) { 625 HeapWord* bottom = first_hr->bottom(); 626 HeapWord* end = first_hr->orig_end(); 627 if ((first + 1) == last) { 628 // the series has a single humongous region 629 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top); 630 } else { 631 // the series has more than one humongous regions 632 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end); 633 } 634 } 635 636 // Now, we will update the top fields of the "continues humongous" 637 // regions. The reason we need to do this is that, otherwise, 638 // these regions would look empty and this will confuse parts of 639 // G1. For example, the code that looks for a consecutive number 640 // of empty regions will consider them empty and try to 641 // re-allocate them. We can extend is_empty() to also include 642 // !is_continues_humongous(), but it is easier to just update the top 643 // fields here. The way we set top for all regions (i.e., top == 644 // end for all regions but the last one, top == new_top for the 645 // last one) is actually used when we will free up the humongous 646 // region in free_humongous_region(). 647 hr = NULL; 648 for (uint i = first + 1; i < last; ++i) { 649 hr = region_at(i); 650 if ((i + 1) == last) { 651 // last continues humongous region 652 assert(hr->bottom() < new_top && new_top <= hr->end(), 653 "new_top should fall on this region"); 654 hr->set_top(new_top); 655 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top); 656 } else { 657 // not last one 658 assert(new_top > hr->end(), "new_top should be above this region"); 659 hr->set_top(hr->end()); 660 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end()); 661 } 662 } 663 // If we have continues humongous regions (hr != NULL), then the 664 // end of the last one should match new_end and its top should 665 // match new_top. 666 assert(hr == NULL || 667 (hr->end() == new_end && hr->top() == new_top), "sanity"); 668 check_bitmaps("Humongous Region Allocation", first_hr); 669 670 assert(first_hr->used() == word_size * HeapWordSize, "invariant"); 671 _allocator->increase_used(first_hr->used()); 672 _humongous_set.add(first_hr); 673 674 return new_obj; 675 } 676 677 // If could fit into free regions w/o expansion, try. 678 // Otherwise, if can expand, do so. 679 // Otherwise, if using ex regions might help, try with ex given back. 680 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) { 681 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 682 683 verify_region_sets_optional(); 684 685 uint first = G1_NO_HRM_INDEX; 686 uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords); 687 688 if (obj_regions == 1) { 689 // Only one region to allocate, try to use a fast path by directly allocating 690 // from the free lists. Do not try to expand here, we will potentially do that 691 // later. 692 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */); 693 if (hr != NULL) { 694 first = hr->hrm_index(); 695 } 696 } else { 697 // We can't allocate humongous regions spanning more than one region while 698 // cleanupComplete() is running, since some of the regions we find to be 699 // empty might not yet be added to the free list. It is not straightforward 700 // to know in which list they are on so that we can remove them. We only 701 // need to do this if we need to allocate more than one region to satisfy the 702 // current humongous allocation request. If we are only allocating one region 703 // we use the one-region region allocation code (see above), that already 704 // potentially waits for regions from the secondary free list. 705 wait_while_free_regions_coming(); 706 append_secondary_free_list_if_not_empty_with_lock(); 707 708 // Policy: Try only empty regions (i.e. already committed first). Maybe we 709 // are lucky enough to find some. 710 first = _hrm.find_contiguous_only_empty(obj_regions); 711 if (first != G1_NO_HRM_INDEX) { 712 _hrm.allocate_free_regions_starting_at(first, obj_regions); 713 } 714 } 715 716 if (first == G1_NO_HRM_INDEX) { 717 // Policy: We could not find enough regions for the humongous object in the 718 // free list. Look through the heap to find a mix of free and uncommitted regions. 719 // If so, try expansion. 720 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions); 721 if (first != G1_NO_HRM_INDEX) { 722 // We found something. Make sure these regions are committed, i.e. expand 723 // the heap. Alternatively we could do a defragmentation GC. 724 ergo_verbose1(ErgoHeapSizing, 725 "attempt heap expansion", 726 ergo_format_reason("humongous allocation request failed") 727 ergo_format_byte("allocation request"), 728 word_size * HeapWordSize); 729 730 _hrm.expand_at(first, obj_regions); 731 g1_policy()->record_new_heap_size(num_regions()); 732 733 #ifdef ASSERT 734 for (uint i = first; i < first + obj_regions; ++i) { 735 HeapRegion* hr = region_at(i); 736 assert(hr->is_free(), "sanity"); 737 assert(hr->is_empty(), "sanity"); 738 assert(is_on_master_free_list(hr), "sanity"); 739 } 740 #endif 741 _hrm.allocate_free_regions_starting_at(first, obj_regions); 742 } else { 743 // Policy: Potentially trigger a defragmentation GC. 744 } 745 } 746 747 HeapWord* result = NULL; 748 if (first != G1_NO_HRM_INDEX) { 749 result = humongous_obj_allocate_initialize_regions(first, obj_regions, 750 word_size, context); 751 assert(result != NULL, "it should always return a valid result"); 752 753 // A successful humongous object allocation changes the used space 754 // information of the old generation so we need to recalculate the 755 // sizes and update the jstat counters here. 756 g1mm()->update_sizes(); 757 } 758 759 verify_region_sets_optional(); 760 761 return result; 762 } 763 764 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) { 765 assert_heap_not_locked_and_not_at_safepoint(); 766 assert(!is_humongous(word_size), "we do not allow humongous TLABs"); 767 768 uint dummy_gc_count_before; 769 uint dummy_gclocker_retry_count = 0; 770 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count); 771 } 772 773 HeapWord* 774 G1CollectedHeap::mem_allocate(size_t word_size, 775 bool* gc_overhead_limit_was_exceeded) { 776 assert_heap_not_locked_and_not_at_safepoint(); 777 778 // Loop until the allocation is satisfied, or unsatisfied after GC. 779 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 780 uint gc_count_before; 781 782 HeapWord* result = NULL; 783 if (!is_humongous(word_size)) { 784 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count); 785 } else { 786 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count); 787 } 788 if (result != NULL) { 789 return result; 790 } 791 792 // Create the garbage collection operation... 793 VM_G1CollectForAllocation op(gc_count_before, word_size); 794 op.set_allocation_context(AllocationContext::current()); 795 796 // ...and get the VM thread to execute it. 797 VMThread::execute(&op); 798 799 if (op.prologue_succeeded() && op.pause_succeeded()) { 800 // If the operation was successful we'll return the result even 801 // if it is NULL. If the allocation attempt failed immediately 802 // after a Full GC, it's unlikely we'll be able to allocate now. 803 HeapWord* result = op.result(); 804 if (result != NULL && !is_humongous(word_size)) { 805 // Allocations that take place on VM operations do not do any 806 // card dirtying and we have to do it here. We only have to do 807 // this for non-humongous allocations, though. 808 dirty_young_block(result, word_size); 809 } 810 return result; 811 } else { 812 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 813 return NULL; 814 } 815 assert(op.result() == NULL, 816 "the result should be NULL if the VM op did not succeed"); 817 } 818 819 // Give a warning if we seem to be looping forever. 820 if ((QueuedAllocationWarningCount > 0) && 821 (try_count % QueuedAllocationWarningCount == 0)) { 822 warning("G1CollectedHeap::mem_allocate retries %d times", try_count); 823 } 824 } 825 826 ShouldNotReachHere(); 827 return NULL; 828 } 829 830 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size, 831 AllocationContext_t context, 832 uint* gc_count_before_ret, 833 uint* gclocker_retry_count_ret) { 834 // Make sure you read the note in attempt_allocation_humongous(). 835 836 assert_heap_not_locked_and_not_at_safepoint(); 837 assert(!is_humongous(word_size), "attempt_allocation_slow() should not " 838 "be called for humongous allocation requests"); 839 840 // We should only get here after the first-level allocation attempt 841 // (attempt_allocation()) failed to allocate. 842 843 // We will loop until a) we manage to successfully perform the 844 // allocation or b) we successfully schedule a collection which 845 // fails to perform the allocation. b) is the only case when we'll 846 // return NULL. 847 HeapWord* result = NULL; 848 for (int try_count = 1; /* we'll return */; try_count += 1) { 849 bool should_try_gc; 850 uint gc_count_before; 851 852 { 853 MutexLockerEx x(Heap_lock); 854 result = _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size, 855 false /* bot_updates */); 856 if (result != NULL) { 857 return result; 858 } 859 860 // If we reach here, attempt_allocation_locked() above failed to 861 // allocate a new region. So the mutator alloc region should be NULL. 862 assert(_allocator->mutator_alloc_region(context)->get() == NULL, "only way to get here"); 863 864 if (GC_locker::is_active_and_needs_gc()) { 865 if (g1_policy()->can_expand_young_list()) { 866 // No need for an ergo verbose message here, 867 // can_expand_young_list() does this when it returns true. 868 result = _allocator->mutator_alloc_region(context)->attempt_allocation_force(word_size, 869 false /* bot_updates */); 870 if (result != NULL) { 871 return result; 872 } 873 } 874 should_try_gc = false; 875 } else { 876 // The GCLocker may not be active but the GCLocker initiated 877 // GC may not yet have been performed (GCLocker::needs_gc() 878 // returns true). In this case we do not try this GC and 879 // wait until the GCLocker initiated GC is performed, and 880 // then retry the allocation. 881 if (GC_locker::needs_gc()) { 882 should_try_gc = false; 883 } else { 884 // Read the GC count while still holding the Heap_lock. 885 gc_count_before = total_collections(); 886 should_try_gc = true; 887 } 888 } 889 } 890 891 if (should_try_gc) { 892 bool succeeded; 893 result = do_collection_pause(word_size, gc_count_before, &succeeded, 894 GCCause::_g1_inc_collection_pause); 895 if (result != NULL) { 896 assert(succeeded, "only way to get back a non-NULL result"); 897 return result; 898 } 899 900 if (succeeded) { 901 // If we get here we successfully scheduled a collection which 902 // failed to allocate. No point in trying to allocate 903 // further. We'll just return NULL. 904 MutexLockerEx x(Heap_lock); 905 *gc_count_before_ret = total_collections(); 906 return NULL; 907 } 908 } else { 909 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { 910 MutexLockerEx x(Heap_lock); 911 *gc_count_before_ret = total_collections(); 912 return NULL; 913 } 914 // The GCLocker is either active or the GCLocker initiated 915 // GC has not yet been performed. Stall until it is and 916 // then retry the allocation. 917 GC_locker::stall_until_clear(); 918 (*gclocker_retry_count_ret) += 1; 919 } 920 921 // We can reach here if we were unsuccessful in scheduling a 922 // collection (because another thread beat us to it) or if we were 923 // stalled due to the GC locker. In either can we should retry the 924 // allocation attempt in case another thread successfully 925 // performed a collection and reclaimed enough space. We do the 926 // first attempt (without holding the Heap_lock) here and the 927 // follow-on attempt will be at the start of the next loop 928 // iteration (after taking the Heap_lock). 929 result = _allocator->mutator_alloc_region(context)->attempt_allocation(word_size, 930 false /* bot_updates */); 931 if (result != NULL) { 932 return result; 933 } 934 935 // Give a warning if we seem to be looping forever. 936 if ((QueuedAllocationWarningCount > 0) && 937 (try_count % QueuedAllocationWarningCount == 0)) { 938 warning("G1CollectedHeap::attempt_allocation_slow() " 939 "retries %d times", try_count); 940 } 941 } 942 943 ShouldNotReachHere(); 944 return NULL; 945 } 946 947 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size, 948 uint* gc_count_before_ret, 949 uint* gclocker_retry_count_ret) { 950 // The structure of this method has a lot of similarities to 951 // attempt_allocation_slow(). The reason these two were not merged 952 // into a single one is that such a method would require several "if 953 // allocation is not humongous do this, otherwise do that" 954 // conditional paths which would obscure its flow. In fact, an early 955 // version of this code did use a unified method which was harder to 956 // follow and, as a result, it had subtle bugs that were hard to 957 // track down. So keeping these two methods separate allows each to 958 // be more readable. It will be good to keep these two in sync as 959 // much as possible. 960 961 assert_heap_not_locked_and_not_at_safepoint(); 962 assert(is_humongous(word_size), "attempt_allocation_humongous() " 963 "should only be called for humongous allocations"); 964 965 // Humongous objects can exhaust the heap quickly, so we should check if we 966 // need to start a marking cycle at each humongous object allocation. We do 967 // the check before we do the actual allocation. The reason for doing it 968 // before the allocation is that we avoid having to keep track of the newly 969 // allocated memory while we do a GC. 970 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation", 971 word_size)) { 972 collect(GCCause::_g1_humongous_allocation); 973 } 974 975 // We will loop until a) we manage to successfully perform the 976 // allocation or b) we successfully schedule a collection which 977 // fails to perform the allocation. b) is the only case when we'll 978 // return NULL. 979 HeapWord* result = NULL; 980 for (int try_count = 1; /* we'll return */; try_count += 1) { 981 bool should_try_gc; 982 uint gc_count_before; 983 984 { 985 MutexLockerEx x(Heap_lock); 986 987 // Given that humongous objects are not allocated in young 988 // regions, we'll first try to do the allocation without doing a 989 // collection hoping that there's enough space in the heap. 990 result = humongous_obj_allocate(word_size, AllocationContext::current()); 991 if (result != NULL) { 992 return result; 993 } 994 995 if (GC_locker::is_active_and_needs_gc()) { 996 should_try_gc = false; 997 } else { 998 // The GCLocker may not be active but the GCLocker initiated 999 // GC may not yet have been performed (GCLocker::needs_gc() 1000 // returns true). In this case we do not try this GC and 1001 // wait until the GCLocker initiated GC is performed, and 1002 // then retry the allocation. 1003 if (GC_locker::needs_gc()) { 1004 should_try_gc = false; 1005 } else { 1006 // Read the GC count while still holding the Heap_lock. 1007 gc_count_before = total_collections(); 1008 should_try_gc = true; 1009 } 1010 } 1011 } 1012 1013 if (should_try_gc) { 1014 // If we failed to allocate the humongous object, we should try to 1015 // do a collection pause (if we're allowed) in case it reclaims 1016 // enough space for the allocation to succeed after the pause. 1017 1018 bool succeeded; 1019 result = do_collection_pause(word_size, gc_count_before, &succeeded, 1020 GCCause::_g1_humongous_allocation); 1021 if (result != NULL) { 1022 assert(succeeded, "only way to get back a non-NULL result"); 1023 return result; 1024 } 1025 1026 if (succeeded) { 1027 // If we get here we successfully scheduled a collection which 1028 // failed to allocate. No point in trying to allocate 1029 // further. We'll just return NULL. 1030 MutexLockerEx x(Heap_lock); 1031 *gc_count_before_ret = total_collections(); 1032 return NULL; 1033 } 1034 } else { 1035 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { 1036 MutexLockerEx x(Heap_lock); 1037 *gc_count_before_ret = total_collections(); 1038 return NULL; 1039 } 1040 // The GCLocker is either active or the GCLocker initiated 1041 // GC has not yet been performed. Stall until it is and 1042 // then retry the allocation. 1043 GC_locker::stall_until_clear(); 1044 (*gclocker_retry_count_ret) += 1; 1045 } 1046 1047 // We can reach here if we were unsuccessful in scheduling a 1048 // collection (because another thread beat us to it) or if we were 1049 // stalled due to the GC locker. In either can we should retry the 1050 // allocation attempt in case another thread successfully 1051 // performed a collection and reclaimed enough space. Give a 1052 // warning if we seem to be looping forever. 1053 1054 if ((QueuedAllocationWarningCount > 0) && 1055 (try_count % QueuedAllocationWarningCount == 0)) { 1056 warning("G1CollectedHeap::attempt_allocation_humongous() " 1057 "retries %d times", try_count); 1058 } 1059 } 1060 1061 ShouldNotReachHere(); 1062 return NULL; 1063 } 1064 1065 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size, 1066 AllocationContext_t context, 1067 bool expect_null_mutator_alloc_region) { 1068 assert_at_safepoint(true /* should_be_vm_thread */); 1069 assert(_allocator->mutator_alloc_region(context)->get() == NULL || 1070 !expect_null_mutator_alloc_region, 1071 "the current alloc region was unexpectedly found to be non-NULL"); 1072 1073 if (!is_humongous(word_size)) { 1074 return _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size, 1075 false /* bot_updates */); 1076 } else { 1077 HeapWord* result = humongous_obj_allocate(word_size, context); 1078 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) { 1079 g1_policy()->set_initiate_conc_mark_if_possible(); 1080 } 1081 return result; 1082 } 1083 1084 ShouldNotReachHere(); 1085 } 1086 1087 class PostMCRemSetClearClosure: public HeapRegionClosure { 1088 G1CollectedHeap* _g1h; 1089 ModRefBarrierSet* _mr_bs; 1090 public: 1091 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) : 1092 _g1h(g1h), _mr_bs(mr_bs) {} 1093 1094 bool doHeapRegion(HeapRegion* r) { 1095 HeapRegionRemSet* hrrs = r->rem_set(); 1096 1097 if (r->is_continues_humongous()) { 1098 // We'll assert that the strong code root list and RSet is empty 1099 assert(hrrs->strong_code_roots_list_length() == 0, "sanity"); 1100 assert(hrrs->occupied() == 0, "RSet should be empty"); 1101 return false; 1102 } 1103 1104 _g1h->reset_gc_time_stamps(r); 1105 hrrs->clear(); 1106 // You might think here that we could clear just the cards 1107 // corresponding to the used region. But no: if we leave a dirty card 1108 // in a region we might allocate into, then it would prevent that card 1109 // from being enqueued, and cause it to be missed. 1110 // Re: the performance cost: we shouldn't be doing full GC anyway! 1111 _mr_bs->clear(MemRegion(r->bottom(), r->end())); 1112 1113 return false; 1114 } 1115 }; 1116 1117 void G1CollectedHeap::clear_rsets_post_compaction() { 1118 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set()); 1119 heap_region_iterate(&rs_clear); 1120 } 1121 1122 class RebuildRSOutOfRegionClosure: public HeapRegionClosure { 1123 G1CollectedHeap* _g1h; 1124 UpdateRSOopClosure _cl; 1125 int _worker_i; 1126 public: 1127 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) : 1128 _cl(g1->g1_rem_set(), worker_i), 1129 _worker_i(worker_i), 1130 _g1h(g1) 1131 { } 1132 1133 bool doHeapRegion(HeapRegion* r) { 1134 if (!r->is_continues_humongous()) { 1135 _cl.set_from(r); 1136 r->oop_iterate(&_cl); 1137 } 1138 return false; 1139 } 1140 }; 1141 1142 class ParRebuildRSTask: public AbstractGangTask { 1143 G1CollectedHeap* _g1; 1144 HeapRegionClaimer _hrclaimer; 1145 1146 public: 1147 ParRebuildRSTask(G1CollectedHeap* g1) : 1148 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {} 1149 1150 void work(uint worker_id) { 1151 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id); 1152 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer); 1153 } 1154 }; 1155 1156 class PostCompactionPrinterClosure: public HeapRegionClosure { 1157 private: 1158 G1HRPrinter* _hr_printer; 1159 public: 1160 bool doHeapRegion(HeapRegion* hr) { 1161 assert(!hr->is_young(), "not expecting to find young regions"); 1162 if (hr->is_free()) { 1163 // We only generate output for non-empty regions. 1164 } else if (hr->is_starts_humongous()) { 1165 if (hr->region_num() == 1) { 1166 // single humongous region 1167 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous); 1168 } else { 1169 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous); 1170 } 1171 } else if (hr->is_continues_humongous()) { 1172 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous); 1173 } else if (hr->is_old()) { 1174 _hr_printer->post_compaction(hr, G1HRPrinter::Old); 1175 } else { 1176 ShouldNotReachHere(); 1177 } 1178 return false; 1179 } 1180 1181 PostCompactionPrinterClosure(G1HRPrinter* hr_printer) 1182 : _hr_printer(hr_printer) { } 1183 }; 1184 1185 void G1CollectedHeap::print_hrm_post_compaction() { 1186 PostCompactionPrinterClosure cl(hr_printer()); 1187 heap_region_iterate(&cl); 1188 } 1189 1190 bool G1CollectedHeap::do_collection(bool explicit_gc, 1191 bool clear_all_soft_refs, 1192 size_t word_size) { 1193 assert_at_safepoint(true /* should_be_vm_thread */); 1194 1195 if (GC_locker::check_active_before_gc()) { 1196 return false; 1197 } 1198 1199 STWGCTimer* gc_timer = G1MarkSweep::gc_timer(); 1200 gc_timer->register_gc_start(); 1201 1202 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer(); 1203 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start()); 1204 1205 SvcGCMarker sgcm(SvcGCMarker::FULL); 1206 ResourceMark rm; 1207 1208 print_heap_before_gc(); 1209 trace_heap_before_gc(gc_tracer); 1210 1211 size_t metadata_prev_used = MetaspaceAux::used_bytes(); 1212 1213 verify_region_sets_optional(); 1214 1215 const bool do_clear_all_soft_refs = clear_all_soft_refs || 1216 collector_policy()->should_clear_all_soft_refs(); 1217 1218 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy()); 1219 1220 { 1221 IsGCActiveMark x; 1222 1223 // Timing 1224 assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant"); 1225 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty); 1226 1227 { 1228 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL, gc_tracer->gc_id()); 1229 TraceCollectorStats tcs(g1mm()->full_collection_counters()); 1230 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause()); 1231 1232 g1_policy()->record_full_collection_start(); 1233 1234 // Note: When we have a more flexible GC logging framework that 1235 // allows us to add optional attributes to a GC log record we 1236 // could consider timing and reporting how long we wait in the 1237 // following two methods. 1238 wait_while_free_regions_coming(); 1239 // If we start the compaction before the CM threads finish 1240 // scanning the root regions we might trip them over as we'll 1241 // be moving objects / updating references. So let's wait until 1242 // they are done. By telling them to abort, they should complete 1243 // early. 1244 _cm->root_regions()->abort(); 1245 _cm->root_regions()->wait_until_scan_finished(); 1246 append_secondary_free_list_if_not_empty_with_lock(); 1247 1248 gc_prologue(true); 1249 increment_total_collections(true /* full gc */); 1250 increment_old_marking_cycles_started(); 1251 1252 assert(used() == recalculate_used(), "Should be equal"); 1253 1254 verify_before_gc(); 1255 1256 check_bitmaps("Full GC Start"); 1257 pre_full_gc_dump(gc_timer); 1258 1259 COMPILER2_PRESENT(DerivedPointerTable::clear()); 1260 1261 // Disable discovery and empty the discovered lists 1262 // for the CM ref processor. 1263 ref_processor_cm()->disable_discovery(); 1264 ref_processor_cm()->abandon_partial_discovery(); 1265 ref_processor_cm()->verify_no_references_recorded(); 1266 1267 // Abandon current iterations of concurrent marking and concurrent 1268 // refinement, if any are in progress. We have to do this before 1269 // wait_until_scan_finished() below. 1270 concurrent_mark()->abort(); 1271 1272 // Make sure we'll choose a new allocation region afterwards. 1273 _allocator->release_mutator_alloc_region(); 1274 _allocator->abandon_gc_alloc_regions(); 1275 g1_rem_set()->cleanupHRRS(); 1276 1277 // We should call this after we retire any currently active alloc 1278 // regions so that all the ALLOC / RETIRE events are generated 1279 // before the start GC event. 1280 _hr_printer.start_gc(true /* full */, (size_t) total_collections()); 1281 1282 // We may have added regions to the current incremental collection 1283 // set between the last GC or pause and now. We need to clear the 1284 // incremental collection set and then start rebuilding it afresh 1285 // after this full GC. 1286 abandon_collection_set(g1_policy()->inc_cset_head()); 1287 g1_policy()->clear_incremental_cset(); 1288 g1_policy()->stop_incremental_cset_building(); 1289 1290 tear_down_region_sets(false /* free_list_only */); 1291 g1_policy()->set_gcs_are_young(true); 1292 1293 // See the comments in g1CollectedHeap.hpp and 1294 // G1CollectedHeap::ref_processing_init() about 1295 // how reference processing currently works in G1. 1296 1297 // Temporarily make discovery by the STW ref processor single threaded (non-MT). 1298 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false); 1299 1300 // Temporarily clear the STW ref processor's _is_alive_non_header field. 1301 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL); 1302 1303 ref_processor_stw()->enable_discovery(); 1304 ref_processor_stw()->setup_policy(do_clear_all_soft_refs); 1305 1306 // Do collection work 1307 { 1308 HandleMark hm; // Discard invalid handles created during gc 1309 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs); 1310 } 1311 1312 assert(num_free_regions() == 0, "we should not have added any free regions"); 1313 rebuild_region_sets(false /* free_list_only */); 1314 1315 // Enqueue any discovered reference objects that have 1316 // not been removed from the discovered lists. 1317 ref_processor_stw()->enqueue_discovered_references(); 1318 1319 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 1320 1321 MemoryService::track_memory_usage(); 1322 1323 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 1324 ref_processor_stw()->verify_no_references_recorded(); 1325 1326 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 1327 ClassLoaderDataGraph::purge(); 1328 MetaspaceAux::verify_metrics(); 1329 1330 // Note: since we've just done a full GC, concurrent 1331 // marking is no longer active. Therefore we need not 1332 // re-enable reference discovery for the CM ref processor. 1333 // That will be done at the start of the next marking cycle. 1334 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition"); 1335 ref_processor_cm()->verify_no_references_recorded(); 1336 1337 reset_gc_time_stamp(); 1338 // Since everything potentially moved, we will clear all remembered 1339 // sets, and clear all cards. Later we will rebuild remembered 1340 // sets. We will also reset the GC time stamps of the regions. 1341 clear_rsets_post_compaction(); 1342 check_gc_time_stamps(); 1343 1344 // Resize the heap if necessary. 1345 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size); 1346 1347 if (_hr_printer.is_active()) { 1348 // We should do this after we potentially resize the heap so 1349 // that all the COMMIT / UNCOMMIT events are generated before 1350 // the end GC event. 1351 1352 print_hrm_post_compaction(); 1353 _hr_printer.end_gc(true /* full */, (size_t) total_collections()); 1354 } 1355 1356 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 1357 if (hot_card_cache->use_cache()) { 1358 hot_card_cache->reset_card_counts(); 1359 hot_card_cache->reset_hot_cache(); 1360 } 1361 1362 // Rebuild remembered sets of all regions. 1363 uint n_workers = 1364 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 1365 workers()->active_workers(), 1366 Threads::number_of_non_daemon_threads()); 1367 assert(UseDynamicNumberOfGCThreads || 1368 n_workers == workers()->total_workers(), 1369 "If not dynamic should be using all the workers"); 1370 workers()->set_active_workers(n_workers); 1371 // Set parallel threads in the heap (_n_par_threads) only 1372 // before a parallel phase and always reset it to 0 after 1373 // the phase so that the number of parallel threads does 1374 // no get carried forward to a serial phase where there 1375 // may be code that is "possibly_parallel". 1376 set_par_threads(n_workers); 1377 1378 ParRebuildRSTask rebuild_rs_task(this); 1379 assert(UseDynamicNumberOfGCThreads || 1380 workers()->active_workers() == workers()->total_workers(), 1381 "Unless dynamic should use total workers"); 1382 // Use the most recent number of active workers 1383 assert(workers()->active_workers() > 0, 1384 "Active workers not properly set"); 1385 set_par_threads(workers()->active_workers()); 1386 workers()->run_task(&rebuild_rs_task); 1387 set_par_threads(0); 1388 1389 // Rebuild the strong code root lists for each region 1390 rebuild_strong_code_roots(); 1391 1392 if (true) { // FIXME 1393 MetaspaceGC::compute_new_size(); 1394 } 1395 1396 #ifdef TRACESPINNING 1397 ParallelTaskTerminator::print_termination_counts(); 1398 #endif 1399 1400 // Discard all rset updates 1401 JavaThread::dirty_card_queue_set().abandon_logs(); 1402 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty"); 1403 1404 _young_list->reset_sampled_info(); 1405 // At this point there should be no regions in the 1406 // entire heap tagged as young. 1407 assert(check_young_list_empty(true /* check_heap */), 1408 "young list should be empty at this point"); 1409 1410 // Update the number of full collections that have been completed. 1411 increment_old_marking_cycles_completed(false /* concurrent */); 1412 1413 _hrm.verify_optional(); 1414 verify_region_sets_optional(); 1415 1416 verify_after_gc(); 1417 1418 // Clear the previous marking bitmap, if needed for bitmap verification. 1419 // Note we cannot do this when we clear the next marking bitmap in 1420 // ConcurrentMark::abort() above since VerifyDuringGC verifies the 1421 // objects marked during a full GC against the previous bitmap. 1422 // But we need to clear it before calling check_bitmaps below since 1423 // the full GC has compacted objects and updated TAMS but not updated 1424 // the prev bitmap. 1425 if (G1VerifyBitmaps) { 1426 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll(); 1427 } 1428 check_bitmaps("Full GC End"); 1429 1430 // Start a new incremental collection set for the next pause 1431 assert(g1_policy()->collection_set() == NULL, "must be"); 1432 g1_policy()->start_incremental_cset_building(); 1433 1434 clear_cset_fast_test(); 1435 1436 _allocator->init_mutator_alloc_region(); 1437 1438 g1_policy()->record_full_collection_end(); 1439 1440 if (G1Log::fine()) { 1441 g1_policy()->print_heap_transition(); 1442 } 1443 1444 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 1445 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 1446 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 1447 // before any GC notifications are raised. 1448 g1mm()->update_sizes(); 1449 1450 gc_epilogue(true); 1451 } 1452 1453 if (G1Log::finer()) { 1454 g1_policy()->print_detailed_heap_transition(true /* full */); 1455 } 1456 1457 print_heap_after_gc(); 1458 trace_heap_after_gc(gc_tracer); 1459 1460 post_full_gc_dump(gc_timer); 1461 1462 gc_timer->register_gc_end(); 1463 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions()); 1464 } 1465 1466 return true; 1467 } 1468 1469 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) { 1470 // do_collection() will return whether it succeeded in performing 1471 // the GC. Currently, there is no facility on the 1472 // do_full_collection() API to notify the caller than the collection 1473 // did not succeed (e.g., because it was locked out by the GC 1474 // locker). So, right now, we'll ignore the return value. 1475 bool dummy = do_collection(true, /* explicit_gc */ 1476 clear_all_soft_refs, 1477 0 /* word_size */); 1478 } 1479 1480 // This code is mostly copied from TenuredGeneration. 1481 void 1482 G1CollectedHeap:: 1483 resize_if_necessary_after_full_collection(size_t word_size) { 1484 // Include the current allocation, if any, and bytes that will be 1485 // pre-allocated to support collections, as "used". 1486 const size_t used_after_gc = used(); 1487 const size_t capacity_after_gc = capacity(); 1488 const size_t free_after_gc = capacity_after_gc - used_after_gc; 1489 1490 // This is enforced in arguments.cpp. 1491 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, 1492 "otherwise the code below doesn't make sense"); 1493 1494 // We don't have floating point command-line arguments 1495 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0; 1496 const double maximum_used_percentage = 1.0 - minimum_free_percentage; 1497 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0; 1498 const double minimum_used_percentage = 1.0 - maximum_free_percentage; 1499 1500 const size_t min_heap_size = collector_policy()->min_heap_byte_size(); 1501 const size_t max_heap_size = collector_policy()->max_heap_byte_size(); 1502 1503 // We have to be careful here as these two calculations can overflow 1504 // 32-bit size_t's. 1505 double used_after_gc_d = (double) used_after_gc; 1506 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage; 1507 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage; 1508 1509 // Let's make sure that they are both under the max heap size, which 1510 // by default will make them fit into a size_t. 1511 double desired_capacity_upper_bound = (double) max_heap_size; 1512 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d, 1513 desired_capacity_upper_bound); 1514 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d, 1515 desired_capacity_upper_bound); 1516 1517 // We can now safely turn them into size_t's. 1518 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d; 1519 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d; 1520 1521 // This assert only makes sense here, before we adjust them 1522 // with respect to the min and max heap size. 1523 assert(minimum_desired_capacity <= maximum_desired_capacity, 1524 err_msg("minimum_desired_capacity = "SIZE_FORMAT", " 1525 "maximum_desired_capacity = "SIZE_FORMAT, 1526 minimum_desired_capacity, maximum_desired_capacity)); 1527 1528 // Should not be greater than the heap max size. No need to adjust 1529 // it with respect to the heap min size as it's a lower bound (i.e., 1530 // we'll try to make the capacity larger than it, not smaller). 1531 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size); 1532 // Should not be less than the heap min size. No need to adjust it 1533 // with respect to the heap max size as it's an upper bound (i.e., 1534 // we'll try to make the capacity smaller than it, not greater). 1535 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size); 1536 1537 if (capacity_after_gc < minimum_desired_capacity) { 1538 // Don't expand unless it's significant 1539 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc; 1540 ergo_verbose4(ErgoHeapSizing, 1541 "attempt heap expansion", 1542 ergo_format_reason("capacity lower than " 1543 "min desired capacity after Full GC") 1544 ergo_format_byte("capacity") 1545 ergo_format_byte("occupancy") 1546 ergo_format_byte_perc("min desired capacity"), 1547 capacity_after_gc, used_after_gc, 1548 minimum_desired_capacity, (double) MinHeapFreeRatio); 1549 expand(expand_bytes); 1550 1551 // No expansion, now see if we want to shrink 1552 } else if (capacity_after_gc > maximum_desired_capacity) { 1553 // Capacity too large, compute shrinking size 1554 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity; 1555 ergo_verbose4(ErgoHeapSizing, 1556 "attempt heap shrinking", 1557 ergo_format_reason("capacity higher than " 1558 "max desired capacity after Full GC") 1559 ergo_format_byte("capacity") 1560 ergo_format_byte("occupancy") 1561 ergo_format_byte_perc("max desired capacity"), 1562 capacity_after_gc, used_after_gc, 1563 maximum_desired_capacity, (double) MaxHeapFreeRatio); 1564 shrink(shrink_bytes); 1565 } 1566 } 1567 1568 1569 HeapWord* 1570 G1CollectedHeap::satisfy_failed_allocation(size_t word_size, 1571 AllocationContext_t context, 1572 bool* succeeded) { 1573 assert_at_safepoint(true /* should_be_vm_thread */); 1574 1575 *succeeded = true; 1576 // Let's attempt the allocation first. 1577 HeapWord* result = 1578 attempt_allocation_at_safepoint(word_size, 1579 context, 1580 false /* expect_null_mutator_alloc_region */); 1581 if (result != NULL) { 1582 assert(*succeeded, "sanity"); 1583 return result; 1584 } 1585 1586 // In a G1 heap, we're supposed to keep allocation from failing by 1587 // incremental pauses. Therefore, at least for now, we'll favor 1588 // expansion over collection. (This might change in the future if we can 1589 // do something smarter than full collection to satisfy a failed alloc.) 1590 result = expand_and_allocate(word_size, context); 1591 if (result != NULL) { 1592 assert(*succeeded, "sanity"); 1593 return result; 1594 } 1595 1596 // Expansion didn't work, we'll try to do a Full GC. 1597 bool gc_succeeded = do_collection(false, /* explicit_gc */ 1598 false, /* clear_all_soft_refs */ 1599 word_size); 1600 if (!gc_succeeded) { 1601 *succeeded = false; 1602 return NULL; 1603 } 1604 1605 // Retry the allocation 1606 result = attempt_allocation_at_safepoint(word_size, 1607 context, 1608 true /* expect_null_mutator_alloc_region */); 1609 if (result != NULL) { 1610 assert(*succeeded, "sanity"); 1611 return result; 1612 } 1613 1614 // Then, try a Full GC that will collect all soft references. 1615 gc_succeeded = do_collection(false, /* explicit_gc */ 1616 true, /* clear_all_soft_refs */ 1617 word_size); 1618 if (!gc_succeeded) { 1619 *succeeded = false; 1620 return NULL; 1621 } 1622 1623 // Retry the allocation once more 1624 result = attempt_allocation_at_safepoint(word_size, 1625 context, 1626 true /* expect_null_mutator_alloc_region */); 1627 if (result != NULL) { 1628 assert(*succeeded, "sanity"); 1629 return result; 1630 } 1631 1632 assert(!collector_policy()->should_clear_all_soft_refs(), 1633 "Flag should have been handled and cleared prior to this point"); 1634 1635 // What else? We might try synchronous finalization later. If the total 1636 // space available is large enough for the allocation, then a more 1637 // complete compaction phase than we've tried so far might be 1638 // appropriate. 1639 assert(*succeeded, "sanity"); 1640 return NULL; 1641 } 1642 1643 // Attempting to expand the heap sufficiently 1644 // to support an allocation of the given "word_size". If 1645 // successful, perform the allocation and return the address of the 1646 // allocated block, or else "NULL". 1647 1648 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) { 1649 assert_at_safepoint(true /* should_be_vm_thread */); 1650 1651 verify_region_sets_optional(); 1652 1653 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes); 1654 ergo_verbose1(ErgoHeapSizing, 1655 "attempt heap expansion", 1656 ergo_format_reason("allocation request failed") 1657 ergo_format_byte("allocation request"), 1658 word_size * HeapWordSize); 1659 if (expand(expand_bytes)) { 1660 _hrm.verify_optional(); 1661 verify_region_sets_optional(); 1662 return attempt_allocation_at_safepoint(word_size, 1663 context, 1664 false /* expect_null_mutator_alloc_region */); 1665 } 1666 return NULL; 1667 } 1668 1669 bool G1CollectedHeap::expand(size_t expand_bytes) { 1670 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); 1671 aligned_expand_bytes = align_size_up(aligned_expand_bytes, 1672 HeapRegion::GrainBytes); 1673 ergo_verbose2(ErgoHeapSizing, 1674 "expand the heap", 1675 ergo_format_byte("requested expansion amount") 1676 ergo_format_byte("attempted expansion amount"), 1677 expand_bytes, aligned_expand_bytes); 1678 1679 if (is_maximal_no_gc()) { 1680 ergo_verbose0(ErgoHeapSizing, 1681 "did not expand the heap", 1682 ergo_format_reason("heap already fully expanded")); 1683 return false; 1684 } 1685 1686 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes); 1687 assert(regions_to_expand > 0, "Must expand by at least one region"); 1688 1689 uint expanded_by = _hrm.expand_by(regions_to_expand); 1690 1691 if (expanded_by > 0) { 1692 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes; 1693 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition"); 1694 g1_policy()->record_new_heap_size(num_regions()); 1695 } else { 1696 ergo_verbose0(ErgoHeapSizing, 1697 "did not expand the heap", 1698 ergo_format_reason("heap expansion operation failed")); 1699 // The expansion of the virtual storage space was unsuccessful. 1700 // Let's see if it was because we ran out of swap. 1701 if (G1ExitOnExpansionFailure && 1702 _hrm.available() >= regions_to_expand) { 1703 // We had head room... 1704 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion"); 1705 } 1706 } 1707 return regions_to_expand > 0; 1708 } 1709 1710 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) { 1711 size_t aligned_shrink_bytes = 1712 ReservedSpace::page_align_size_down(shrink_bytes); 1713 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes, 1714 HeapRegion::GrainBytes); 1715 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes); 1716 1717 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove); 1718 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes; 1719 1720 ergo_verbose3(ErgoHeapSizing, 1721 "shrink the heap", 1722 ergo_format_byte("requested shrinking amount") 1723 ergo_format_byte("aligned shrinking amount") 1724 ergo_format_byte("attempted shrinking amount"), 1725 shrink_bytes, aligned_shrink_bytes, shrunk_bytes); 1726 if (num_regions_removed > 0) { 1727 g1_policy()->record_new_heap_size(num_regions()); 1728 } else { 1729 ergo_verbose0(ErgoHeapSizing, 1730 "did not shrink the heap", 1731 ergo_format_reason("heap shrinking operation failed")); 1732 } 1733 } 1734 1735 void G1CollectedHeap::shrink(size_t shrink_bytes) { 1736 verify_region_sets_optional(); 1737 1738 // We should only reach here at the end of a Full GC which means we 1739 // should not not be holding to any GC alloc regions. The method 1740 // below will make sure of that and do any remaining clean up. 1741 _allocator->abandon_gc_alloc_regions(); 1742 1743 // Instead of tearing down / rebuilding the free lists here, we 1744 // could instead use the remove_all_pending() method on free_list to 1745 // remove only the ones that we need to remove. 1746 tear_down_region_sets(true /* free_list_only */); 1747 shrink_helper(shrink_bytes); 1748 rebuild_region_sets(true /* free_list_only */); 1749 1750 _hrm.verify_optional(); 1751 verify_region_sets_optional(); 1752 } 1753 1754 // Public methods. 1755 1756 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away 1757 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list 1758 #endif // _MSC_VER 1759 1760 1761 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) : 1762 SharedHeap(policy_), 1763 _g1_policy(policy_), 1764 _dirty_card_queue_set(false), 1765 _into_cset_dirty_card_queue_set(false), 1766 _is_alive_closure_cm(this), 1767 _is_alive_closure_stw(this), 1768 _ref_processor_cm(NULL), 1769 _ref_processor_stw(NULL), 1770 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)), 1771 _bot_shared(NULL), 1772 _evac_failure_scan_stack(NULL), 1773 _mark_in_progress(false), 1774 _cg1r(NULL), 1775 _g1mm(NULL), 1776 _refine_cte_cl(NULL), 1777 _full_collection(false), 1778 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()), 1779 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()), 1780 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()), 1781 _humongous_is_live(), 1782 _has_humongous_reclaim_candidates(false), 1783 _free_regions_coming(false), 1784 _young_list(new YoungList(this)), 1785 _gc_time_stamp(0), 1786 _survivor_plab_stats(YoungPLABSize, PLABWeight), 1787 _old_plab_stats(OldPLABSize, PLABWeight), 1788 _expand_heap_after_alloc_failure(true), 1789 _surviving_young_words(NULL), 1790 _old_marking_cycles_started(0), 1791 _old_marking_cycles_completed(0), 1792 _concurrent_cycle_started(false), 1793 _heap_summary_sent(false), 1794 _in_cset_fast_test(), 1795 _dirty_cards_region_list(NULL), 1796 _worker_cset_start_region(NULL), 1797 _worker_cset_start_region_time_stamp(NULL), 1798 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()), 1799 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()), 1800 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()), 1801 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) { 1802 1803 _g1h = this; 1804 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) { 1805 vm_exit_during_initialization("Failed necessary allocation."); 1806 } 1807 1808 _allocator = G1Allocator::create_allocator(_g1h); 1809 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2; 1810 1811 int n_queues = MAX2((int)ParallelGCThreads, 1); 1812 _task_queues = new RefToScanQueueSet(n_queues); 1813 1814 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets(); 1815 assert(n_rem_sets > 0, "Invariant."); 1816 1817 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC); 1818 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC); 1819 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC); 1820 1821 for (int i = 0; i < n_queues; i++) { 1822 RefToScanQueue* q = new RefToScanQueue(); 1823 q->initialize(); 1824 _task_queues->register_queue(i, q); 1825 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo(); 1826 } 1827 clear_cset_start_regions(); 1828 1829 // Initialize the G1EvacuationFailureALot counters and flags. 1830 NOT_PRODUCT(reset_evacuation_should_fail();) 1831 1832 guarantee(_task_queues != NULL, "task_queues allocation failure."); 1833 } 1834 1835 jint G1CollectedHeap::initialize() { 1836 CollectedHeap::pre_initialize(); 1837 os::enable_vtime(); 1838 1839 G1Log::init(); 1840 1841 // Necessary to satisfy locking discipline assertions. 1842 1843 MutexLocker x(Heap_lock); 1844 1845 // We have to initialize the printer before committing the heap, as 1846 // it will be used then. 1847 _hr_printer.set_active(G1PrintHeapRegions); 1848 1849 // While there are no constraints in the GC code that HeapWordSize 1850 // be any particular value, there are multiple other areas in the 1851 // system which believe this to be true (e.g. oop->object_size in some 1852 // cases incorrectly returns the size in wordSize units rather than 1853 // HeapWordSize). 1854 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 1855 1856 size_t init_byte_size = collector_policy()->initial_heap_byte_size(); 1857 size_t max_byte_size = collector_policy()->max_heap_byte_size(); 1858 size_t heap_alignment = collector_policy()->heap_alignment(); 1859 1860 // Ensure that the sizes are properly aligned. 1861 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1862 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1863 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap"); 1864 1865 _refine_cte_cl = new RefineCardTableEntryClosure(); 1866 1867 _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl); 1868 1869 // Reserve the maximum. 1870 1871 // When compressed oops are enabled, the preferred heap base 1872 // is calculated by subtracting the requested size from the 1873 // 32Gb boundary and using the result as the base address for 1874 // heap reservation. If the requested size is not aligned to 1875 // HeapRegion::GrainBytes (i.e. the alignment that is passed 1876 // into the ReservedHeapSpace constructor) then the actual 1877 // base of the reserved heap may end up differing from the 1878 // address that was requested (i.e. the preferred heap base). 1879 // If this happens then we could end up using a non-optimal 1880 // compressed oops mode. 1881 1882 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size, 1883 heap_alignment); 1884 1885 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size())); 1886 1887 // Create the barrier set for the entire reserved region. 1888 G1SATBCardTableLoggingModRefBS* bs 1889 = new G1SATBCardTableLoggingModRefBS(reserved_region()); 1890 bs->initialize(); 1891 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity"); 1892 set_barrier_set(bs); 1893 1894 // Also create a G1 rem set. 1895 _g1_rem_set = new G1RemSet(this, g1_barrier_set()); 1896 1897 // Carve out the G1 part of the heap. 1898 1899 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size); 1900 G1RegionToSpaceMapper* heap_storage = 1901 G1RegionToSpaceMapper::create_mapper(g1_rs, 1902 UseLargePages ? os::large_page_size() : os::vm_page_size(), 1903 HeapRegion::GrainBytes, 1904 1, 1905 mtJavaHeap); 1906 heap_storage->set_mapping_changed_listener(&_listener); 1907 1908 // Reserve space for the block offset table. We do not support automatic uncommit 1909 // for the card table at this time. BOT only. 1910 ReservedSpace bot_rs(G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize)); 1911 G1RegionToSpaceMapper* bot_storage = 1912 G1RegionToSpaceMapper::create_mapper(bot_rs, 1913 os::vm_page_size(), 1914 HeapRegion::GrainBytes, 1915 G1BlockOffsetSharedArray::N_bytes, 1916 mtGC); 1917 1918 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize)); 1919 G1RegionToSpaceMapper* cardtable_storage = 1920 G1RegionToSpaceMapper::create_mapper(cardtable_rs, 1921 os::vm_page_size(), 1922 HeapRegion::GrainBytes, 1923 G1BlockOffsetSharedArray::N_bytes, 1924 mtGC); 1925 1926 // Reserve space for the card counts table. 1927 ReservedSpace card_counts_rs(G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize)); 1928 G1RegionToSpaceMapper* card_counts_storage = 1929 G1RegionToSpaceMapper::create_mapper(card_counts_rs, 1930 os::vm_page_size(), 1931 HeapRegion::GrainBytes, 1932 G1BlockOffsetSharedArray::N_bytes, 1933 mtGC); 1934 1935 // Reserve space for prev and next bitmap. 1936 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size()); 1937 1938 ReservedSpace prev_bitmap_rs(ReservedSpace::allocation_align_size_up(bitmap_size)); 1939 G1RegionToSpaceMapper* prev_bitmap_storage = 1940 G1RegionToSpaceMapper::create_mapper(prev_bitmap_rs, 1941 os::vm_page_size(), 1942 HeapRegion::GrainBytes, 1943 CMBitMap::mark_distance(), 1944 mtGC); 1945 1946 ReservedSpace next_bitmap_rs(ReservedSpace::allocation_align_size_up(bitmap_size)); 1947 G1RegionToSpaceMapper* next_bitmap_storage = 1948 G1RegionToSpaceMapper::create_mapper(next_bitmap_rs, 1949 os::vm_page_size(), 1950 HeapRegion::GrainBytes, 1951 CMBitMap::mark_distance(), 1952 mtGC); 1953 1954 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage); 1955 g1_barrier_set()->initialize(cardtable_storage); 1956 // Do later initialization work for concurrent refinement. 1957 _cg1r->init(card_counts_storage); 1958 1959 // 6843694 - ensure that the maximum region index can fit 1960 // in the remembered set structures. 1961 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; 1962 guarantee((max_regions() - 1) <= max_region_idx, "too many regions"); 1963 1964 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; 1965 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); 1966 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region, 1967 "too many cards per region"); 1968 1969 FreeRegionList::set_unrealistically_long_length(max_regions() + 1); 1970 1971 _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage); 1972 1973 _g1h = this; 1974 1975 _in_cset_fast_test.initialize(_hrm.reserved().start(), _hrm.reserved().end(), HeapRegion::GrainBytes); 1976 _humongous_is_live.initialize(_hrm.reserved().start(), _hrm.reserved().end(), HeapRegion::GrainBytes); 1977 1978 // Create the ConcurrentMark data structure and thread. 1979 // (Must do this late, so that "max_regions" is defined.) 1980 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage); 1981 if (_cm == NULL || !_cm->completed_initialization()) { 1982 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark"); 1983 return JNI_ENOMEM; 1984 } 1985 _cmThread = _cm->cmThread(); 1986 1987 // Initialize the from_card cache structure of HeapRegionRemSet. 1988 HeapRegionRemSet::init_heap(max_regions()); 1989 1990 // Now expand into the initial heap size. 1991 if (!expand(init_byte_size)) { 1992 vm_shutdown_during_initialization("Failed to allocate initial heap."); 1993 return JNI_ENOMEM; 1994 } 1995 1996 // Perform any initialization actions delegated to the policy. 1997 g1_policy()->init(); 1998 1999 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon, 2000 SATB_Q_FL_lock, 2001 G1SATBProcessCompletedThreshold, 2002 Shared_SATB_Q_lock); 2003 2004 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl, 2005 DirtyCardQ_CBL_mon, 2006 DirtyCardQ_FL_lock, 2007 concurrent_g1_refine()->yellow_zone(), 2008 concurrent_g1_refine()->red_zone(), 2009 Shared_DirtyCardQ_lock); 2010 2011 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code 2012 DirtyCardQ_CBL_mon, 2013 DirtyCardQ_FL_lock, 2014 -1, // never trigger processing 2015 -1, // no limit on length 2016 Shared_DirtyCardQ_lock, 2017 &JavaThread::dirty_card_queue_set()); 2018 2019 // Initialize the card queue set used to hold cards containing 2020 // references into the collection set. 2021 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code 2022 DirtyCardQ_CBL_mon, 2023 DirtyCardQ_FL_lock, 2024 -1, // never trigger processing 2025 -1, // no limit on length 2026 Shared_DirtyCardQ_lock, 2027 &JavaThread::dirty_card_queue_set()); 2028 2029 // Here we allocate the dummy HeapRegion that is required by the 2030 // G1AllocRegion class. 2031 HeapRegion* dummy_region = _hrm.get_dummy_region(); 2032 2033 // We'll re-use the same region whether the alloc region will 2034 // require BOT updates or not and, if it doesn't, then a non-young 2035 // region will complain that it cannot support allocations without 2036 // BOT updates. So we'll tag the dummy region as eden to avoid that. 2037 dummy_region->set_eden(); 2038 // Make sure it's full. 2039 dummy_region->set_top(dummy_region->end()); 2040 G1AllocRegion::setup(this, dummy_region); 2041 2042 _allocator->init_mutator_alloc_region(); 2043 2044 // Do create of the monitoring and management support so that 2045 // values in the heap have been properly initialized. 2046 _g1mm = new G1MonitoringSupport(this); 2047 2048 G1StringDedup::initialize(); 2049 2050 return JNI_OK; 2051 } 2052 2053 void G1CollectedHeap::stop() { 2054 // Stop all concurrent threads. We do this to make sure these threads 2055 // do not continue to execute and access resources (e.g. gclog_or_tty) 2056 // that are destroyed during shutdown. 2057 _cg1r->stop(); 2058 _cmThread->stop(); 2059 if (G1StringDedup::is_enabled()) { 2060 G1StringDedup::stop(); 2061 } 2062 } 2063 2064 void G1CollectedHeap::clear_humongous_is_live_table() { 2065 guarantee(G1EagerReclaimHumongousObjects, "Should only be called if true"); 2066 _humongous_is_live.clear(); 2067 } 2068 2069 size_t G1CollectedHeap::conservative_max_heap_alignment() { 2070 return HeapRegion::max_region_size(); 2071 } 2072 2073 void G1CollectedHeap::ref_processing_init() { 2074 // Reference processing in G1 currently works as follows: 2075 // 2076 // * There are two reference processor instances. One is 2077 // used to record and process discovered references 2078 // during concurrent marking; the other is used to 2079 // record and process references during STW pauses 2080 // (both full and incremental). 2081 // * Both ref processors need to 'span' the entire heap as 2082 // the regions in the collection set may be dotted around. 2083 // 2084 // * For the concurrent marking ref processor: 2085 // * Reference discovery is enabled at initial marking. 2086 // * Reference discovery is disabled and the discovered 2087 // references processed etc during remarking. 2088 // * Reference discovery is MT (see below). 2089 // * Reference discovery requires a barrier (see below). 2090 // * Reference processing may or may not be MT 2091 // (depending on the value of ParallelRefProcEnabled 2092 // and ParallelGCThreads). 2093 // * A full GC disables reference discovery by the CM 2094 // ref processor and abandons any entries on it's 2095 // discovered lists. 2096 // 2097 // * For the STW processor: 2098 // * Non MT discovery is enabled at the start of a full GC. 2099 // * Processing and enqueueing during a full GC is non-MT. 2100 // * During a full GC, references are processed after marking. 2101 // 2102 // * Discovery (may or may not be MT) is enabled at the start 2103 // of an incremental evacuation pause. 2104 // * References are processed near the end of a STW evacuation pause. 2105 // * For both types of GC: 2106 // * Discovery is atomic - i.e. not concurrent. 2107 // * Reference discovery will not need a barrier. 2108 2109 SharedHeap::ref_processing_init(); 2110 MemRegion mr = reserved_region(); 2111 2112 // Concurrent Mark ref processor 2113 _ref_processor_cm = 2114 new ReferenceProcessor(mr, // span 2115 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2116 // mt processing 2117 (int) ParallelGCThreads, 2118 // degree of mt processing 2119 (ParallelGCThreads > 1) || (ConcGCThreads > 1), 2120 // mt discovery 2121 (int) MAX2(ParallelGCThreads, ConcGCThreads), 2122 // degree of mt discovery 2123 false, 2124 // Reference discovery is not atomic 2125 &_is_alive_closure_cm); 2126 // is alive closure 2127 // (for efficiency/performance) 2128 2129 // STW ref processor 2130 _ref_processor_stw = 2131 new ReferenceProcessor(mr, // span 2132 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2133 // mt processing 2134 MAX2((int)ParallelGCThreads, 1), 2135 // degree of mt processing 2136 (ParallelGCThreads > 1), 2137 // mt discovery 2138 MAX2((int)ParallelGCThreads, 1), 2139 // degree of mt discovery 2140 true, 2141 // Reference discovery is atomic 2142 &_is_alive_closure_stw); 2143 // is alive closure 2144 // (for efficiency/performance) 2145 } 2146 2147 size_t G1CollectedHeap::capacity() const { 2148 return _hrm.length() * HeapRegion::GrainBytes; 2149 } 2150 2151 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) { 2152 assert(!hr->is_continues_humongous(), "pre-condition"); 2153 hr->reset_gc_time_stamp(); 2154 if (hr->is_starts_humongous()) { 2155 uint first_index = hr->hrm_index() + 1; 2156 uint last_index = hr->last_hc_index(); 2157 for (uint i = first_index; i < last_index; i += 1) { 2158 HeapRegion* chr = region_at(i); 2159 assert(chr->is_continues_humongous(), "sanity"); 2160 chr->reset_gc_time_stamp(); 2161 } 2162 } 2163 } 2164 2165 #ifndef PRODUCT 2166 class CheckGCTimeStampsHRClosure : public HeapRegionClosure { 2167 private: 2168 unsigned _gc_time_stamp; 2169 bool _failures; 2170 2171 public: 2172 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) : 2173 _gc_time_stamp(gc_time_stamp), _failures(false) { } 2174 2175 virtual bool doHeapRegion(HeapRegion* hr) { 2176 unsigned region_gc_time_stamp = hr->get_gc_time_stamp(); 2177 if (_gc_time_stamp != region_gc_time_stamp) { 2178 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, " 2179 "expected %d", HR_FORMAT_PARAMS(hr), 2180 region_gc_time_stamp, _gc_time_stamp); 2181 _failures = true; 2182 } 2183 return false; 2184 } 2185 2186 bool failures() { return _failures; } 2187 }; 2188 2189 void G1CollectedHeap::check_gc_time_stamps() { 2190 CheckGCTimeStampsHRClosure cl(_gc_time_stamp); 2191 heap_region_iterate(&cl); 2192 guarantee(!cl.failures(), "all GC time stamps should have been reset"); 2193 } 2194 #endif // PRODUCT 2195 2196 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, 2197 DirtyCardQueue* into_cset_dcq, 2198 bool concurrent, 2199 uint worker_i) { 2200 // Clean cards in the hot card cache 2201 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 2202 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq); 2203 2204 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 2205 size_t n_completed_buffers = 0; 2206 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) { 2207 n_completed_buffers++; 2208 } 2209 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers); 2210 dcqs.clear_n_completed_buffers(); 2211 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!"); 2212 } 2213 2214 2215 // Computes the sum of the storage used by the various regions. 2216 size_t G1CollectedHeap::used() const { 2217 return _allocator->used(); 2218 } 2219 2220 size_t G1CollectedHeap::used_unlocked() const { 2221 return _allocator->used_unlocked(); 2222 } 2223 2224 class SumUsedClosure: public HeapRegionClosure { 2225 size_t _used; 2226 public: 2227 SumUsedClosure() : _used(0) {} 2228 bool doHeapRegion(HeapRegion* r) { 2229 if (!r->is_continues_humongous()) { 2230 _used += r->used(); 2231 } 2232 return false; 2233 } 2234 size_t result() { return _used; } 2235 }; 2236 2237 size_t G1CollectedHeap::recalculate_used() const { 2238 double recalculate_used_start = os::elapsedTime(); 2239 2240 SumUsedClosure blk; 2241 heap_region_iterate(&blk); 2242 2243 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0); 2244 return blk.result(); 2245 } 2246 2247 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 2248 switch (cause) { 2249 case GCCause::_gc_locker: return GCLockerInvokesConcurrent; 2250 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent; 2251 case GCCause::_g1_humongous_allocation: return true; 2252 case GCCause::_update_allocation_context_stats_inc: return true; 2253 case GCCause::_wb_conc_mark: return true; 2254 default: return false; 2255 } 2256 } 2257 2258 #ifndef PRODUCT 2259 void G1CollectedHeap::allocate_dummy_regions() { 2260 // Let's fill up most of the region 2261 size_t word_size = HeapRegion::GrainWords - 1024; 2262 // And as a result the region we'll allocate will be humongous. 2263 guarantee(is_humongous(word_size), "sanity"); 2264 2265 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) { 2266 // Let's use the existing mechanism for the allocation 2267 HeapWord* dummy_obj = humongous_obj_allocate(word_size, 2268 AllocationContext::system()); 2269 if (dummy_obj != NULL) { 2270 MemRegion mr(dummy_obj, word_size); 2271 CollectedHeap::fill_with_object(mr); 2272 } else { 2273 // If we can't allocate once, we probably cannot allocate 2274 // again. Let's get out of the loop. 2275 break; 2276 } 2277 } 2278 } 2279 #endif // !PRODUCT 2280 2281 void G1CollectedHeap::increment_old_marking_cycles_started() { 2282 assert(_old_marking_cycles_started == _old_marking_cycles_completed || 2283 _old_marking_cycles_started == _old_marking_cycles_completed + 1, 2284 err_msg("Wrong marking cycle count (started: %d, completed: %d)", 2285 _old_marking_cycles_started, _old_marking_cycles_completed)); 2286 2287 _old_marking_cycles_started++; 2288 } 2289 2290 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) { 2291 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 2292 2293 // We assume that if concurrent == true, then the caller is a 2294 // concurrent thread that was joined the Suspendible Thread 2295 // Set. If there's ever a cheap way to check this, we should add an 2296 // assert here. 2297 2298 // Given that this method is called at the end of a Full GC or of a 2299 // concurrent cycle, and those can be nested (i.e., a Full GC can 2300 // interrupt a concurrent cycle), the number of full collections 2301 // completed should be either one (in the case where there was no 2302 // nesting) or two (when a Full GC interrupted a concurrent cycle) 2303 // behind the number of full collections started. 2304 2305 // This is the case for the inner caller, i.e. a Full GC. 2306 assert(concurrent || 2307 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || 2308 (_old_marking_cycles_started == _old_marking_cycles_completed + 2), 2309 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u " 2310 "is inconsistent with _old_marking_cycles_completed = %u", 2311 _old_marking_cycles_started, _old_marking_cycles_completed)); 2312 2313 // This is the case for the outer caller, i.e. the concurrent cycle. 2314 assert(!concurrent || 2315 (_old_marking_cycles_started == _old_marking_cycles_completed + 1), 2316 err_msg("for outer caller (concurrent cycle): " 2317 "_old_marking_cycles_started = %u " 2318 "is inconsistent with _old_marking_cycles_completed = %u", 2319 _old_marking_cycles_started, _old_marking_cycles_completed)); 2320 2321 _old_marking_cycles_completed += 1; 2322 2323 // We need to clear the "in_progress" flag in the CM thread before 2324 // we wake up any waiters (especially when ExplicitInvokesConcurrent 2325 // is set) so that if a waiter requests another System.gc() it doesn't 2326 // incorrectly see that a marking cycle is still in progress. 2327 if (concurrent) { 2328 _cmThread->clear_in_progress(); 2329 } 2330 2331 // This notify_all() will ensure that a thread that called 2332 // System.gc() with (with ExplicitGCInvokesConcurrent set or not) 2333 // and it's waiting for a full GC to finish will be woken up. It is 2334 // waiting in VM_G1IncCollectionPause::doit_epilogue(). 2335 FullGCCount_lock->notify_all(); 2336 } 2337 2338 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) { 2339 _concurrent_cycle_started = true; 2340 _gc_timer_cm->register_gc_start(start_time); 2341 2342 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start()); 2343 trace_heap_before_gc(_gc_tracer_cm); 2344 } 2345 2346 void G1CollectedHeap::register_concurrent_cycle_end() { 2347 if (_concurrent_cycle_started) { 2348 if (_cm->has_aborted()) { 2349 _gc_tracer_cm->report_concurrent_mode_failure(); 2350 } 2351 2352 _gc_timer_cm->register_gc_end(); 2353 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions()); 2354 2355 // Clear state variables to prepare for the next concurrent cycle. 2356 _concurrent_cycle_started = false; 2357 _heap_summary_sent = false; 2358 } 2359 } 2360 2361 void G1CollectedHeap::trace_heap_after_concurrent_cycle() { 2362 if (_concurrent_cycle_started) { 2363 // This function can be called when: 2364 // the cleanup pause is run 2365 // the concurrent cycle is aborted before the cleanup pause. 2366 // the concurrent cycle is aborted after the cleanup pause, 2367 // but before the concurrent cycle end has been registered. 2368 // Make sure that we only send the heap information once. 2369 if (!_heap_summary_sent) { 2370 trace_heap_after_gc(_gc_tracer_cm); 2371 _heap_summary_sent = true; 2372 } 2373 } 2374 } 2375 2376 G1YCType G1CollectedHeap::yc_type() { 2377 bool is_young = g1_policy()->gcs_are_young(); 2378 bool is_initial_mark = g1_policy()->during_initial_mark_pause(); 2379 bool is_during_mark = mark_in_progress(); 2380 2381 if (is_initial_mark) { 2382 return InitialMark; 2383 } else if (is_during_mark) { 2384 return DuringMark; 2385 } else if (is_young) { 2386 return Normal; 2387 } else { 2388 return Mixed; 2389 } 2390 } 2391 2392 void G1CollectedHeap::collect(GCCause::Cause cause) { 2393 assert_heap_not_locked(); 2394 2395 uint gc_count_before; 2396 uint old_marking_count_before; 2397 uint full_gc_count_before; 2398 bool retry_gc; 2399 2400 do { 2401 retry_gc = false; 2402 2403 { 2404 MutexLocker ml(Heap_lock); 2405 2406 // Read the GC count while holding the Heap_lock 2407 gc_count_before = total_collections(); 2408 full_gc_count_before = total_full_collections(); 2409 old_marking_count_before = _old_marking_cycles_started; 2410 } 2411 2412 if (should_do_concurrent_full_gc(cause)) { 2413 // Schedule an initial-mark evacuation pause that will start a 2414 // concurrent cycle. We're setting word_size to 0 which means that 2415 // we are not requesting a post-GC allocation. 2416 VM_G1IncCollectionPause op(gc_count_before, 2417 0, /* word_size */ 2418 true, /* should_initiate_conc_mark */ 2419 g1_policy()->max_pause_time_ms(), 2420 cause); 2421 op.set_allocation_context(AllocationContext::current()); 2422 2423 VMThread::execute(&op); 2424 if (!op.pause_succeeded()) { 2425 if (old_marking_count_before == _old_marking_cycles_started) { 2426 retry_gc = op.should_retry_gc(); 2427 } else { 2428 // A Full GC happened while we were trying to schedule the 2429 // initial-mark GC. No point in starting a new cycle given 2430 // that the whole heap was collected anyway. 2431 } 2432 2433 if (retry_gc) { 2434 if (GC_locker::is_active_and_needs_gc()) { 2435 GC_locker::stall_until_clear(); 2436 } 2437 } 2438 } 2439 } else { 2440 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc 2441 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { 2442 2443 // Schedule a standard evacuation pause. We're setting word_size 2444 // to 0 which means that we are not requesting a post-GC allocation. 2445 VM_G1IncCollectionPause op(gc_count_before, 2446 0, /* word_size */ 2447 false, /* should_initiate_conc_mark */ 2448 g1_policy()->max_pause_time_ms(), 2449 cause); 2450 VMThread::execute(&op); 2451 } else { 2452 // Schedule a Full GC. 2453 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause); 2454 VMThread::execute(&op); 2455 } 2456 } 2457 } while (retry_gc); 2458 } 2459 2460 bool G1CollectedHeap::is_in(const void* p) const { 2461 if (_hrm.reserved().contains(p)) { 2462 // Given that we know that p is in the reserved space, 2463 // heap_region_containing_raw() should successfully 2464 // return the containing region. 2465 HeapRegion* hr = heap_region_containing_raw(p); 2466 return hr->is_in(p); 2467 } else { 2468 return false; 2469 } 2470 } 2471 2472 #ifdef ASSERT 2473 bool G1CollectedHeap::is_in_exact(const void* p) const { 2474 bool contains = reserved_region().contains(p); 2475 bool available = _hrm.is_available(addr_to_region((HeapWord*)p)); 2476 if (contains && available) { 2477 return true; 2478 } else { 2479 return false; 2480 } 2481 } 2482 #endif 2483 2484 // Iteration functions. 2485 2486 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion. 2487 2488 class IterateOopClosureRegionClosure: public HeapRegionClosure { 2489 ExtendedOopClosure* _cl; 2490 public: 2491 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {} 2492 bool doHeapRegion(HeapRegion* r) { 2493 if (!r->is_continues_humongous()) { 2494 r->oop_iterate(_cl); 2495 } 2496 return false; 2497 } 2498 }; 2499 2500 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) { 2501 IterateOopClosureRegionClosure blk(cl); 2502 heap_region_iterate(&blk); 2503 } 2504 2505 // Iterates an ObjectClosure over all objects within a HeapRegion. 2506 2507 class IterateObjectClosureRegionClosure: public HeapRegionClosure { 2508 ObjectClosure* _cl; 2509 public: 2510 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} 2511 bool doHeapRegion(HeapRegion* r) { 2512 if (!r->is_continues_humongous()) { 2513 r->object_iterate(_cl); 2514 } 2515 return false; 2516 } 2517 }; 2518 2519 void G1CollectedHeap::object_iterate(ObjectClosure* cl) { 2520 IterateObjectClosureRegionClosure blk(cl); 2521 heap_region_iterate(&blk); 2522 } 2523 2524 // Calls a SpaceClosure on a HeapRegion. 2525 2526 class SpaceClosureRegionClosure: public HeapRegionClosure { 2527 SpaceClosure* _cl; 2528 public: 2529 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {} 2530 bool doHeapRegion(HeapRegion* r) { 2531 _cl->do_space(r); 2532 return false; 2533 } 2534 }; 2535 2536 void G1CollectedHeap::space_iterate(SpaceClosure* cl) { 2537 SpaceClosureRegionClosure blk(cl); 2538 heap_region_iterate(&blk); 2539 } 2540 2541 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { 2542 _hrm.iterate(cl); 2543 } 2544 2545 void 2546 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl, 2547 uint worker_id, 2548 HeapRegionClaimer *hrclaimer, 2549 bool concurrent) const { 2550 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent); 2551 } 2552 2553 // Clear the cached CSet starting regions and (more importantly) 2554 // the time stamps. Called when we reset the GC time stamp. 2555 void G1CollectedHeap::clear_cset_start_regions() { 2556 assert(_worker_cset_start_region != NULL, "sanity"); 2557 assert(_worker_cset_start_region_time_stamp != NULL, "sanity"); 2558 2559 int n_queues = MAX2((int)ParallelGCThreads, 1); 2560 for (int i = 0; i < n_queues; i++) { 2561 _worker_cset_start_region[i] = NULL; 2562 _worker_cset_start_region_time_stamp[i] = 0; 2563 } 2564 } 2565 2566 // Given the id of a worker, obtain or calculate a suitable 2567 // starting region for iterating over the current collection set. 2568 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) { 2569 assert(get_gc_time_stamp() > 0, "should have been updated by now"); 2570 2571 HeapRegion* result = NULL; 2572 unsigned gc_time_stamp = get_gc_time_stamp(); 2573 2574 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) { 2575 // Cached starting region for current worker was set 2576 // during the current pause - so it's valid. 2577 // Note: the cached starting heap region may be NULL 2578 // (when the collection set is empty). 2579 result = _worker_cset_start_region[worker_i]; 2580 assert(result == NULL || result->in_collection_set(), "sanity"); 2581 return result; 2582 } 2583 2584 // The cached entry was not valid so let's calculate 2585 // a suitable starting heap region for this worker. 2586 2587 // We want the parallel threads to start their collection 2588 // set iteration at different collection set regions to 2589 // avoid contention. 2590 // If we have: 2591 // n collection set regions 2592 // p threads 2593 // Then thread t will start at region floor ((t * n) / p) 2594 2595 result = g1_policy()->collection_set(); 2596 uint cs_size = g1_policy()->cset_region_length(); 2597 uint active_workers = workers()->active_workers(); 2598 assert(UseDynamicNumberOfGCThreads || 2599 active_workers == workers()->total_workers(), 2600 "Unless dynamic should use total workers"); 2601 2602 uint end_ind = (cs_size * worker_i) / active_workers; 2603 uint start_ind = 0; 2604 2605 if (worker_i > 0 && 2606 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) { 2607 // Previous workers starting region is valid 2608 // so let's iterate from there 2609 start_ind = (cs_size * (worker_i - 1)) / active_workers; 2610 result = _worker_cset_start_region[worker_i - 1]; 2611 } 2612 2613 for (uint i = start_ind; i < end_ind; i++) { 2614 result = result->next_in_collection_set(); 2615 } 2616 2617 // Note: the calculated starting heap region may be NULL 2618 // (when the collection set is empty). 2619 assert(result == NULL || result->in_collection_set(), "sanity"); 2620 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp, 2621 "should be updated only once per pause"); 2622 _worker_cset_start_region[worker_i] = result; 2623 OrderAccess::storestore(); 2624 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp; 2625 return result; 2626 } 2627 2628 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) { 2629 HeapRegion* r = g1_policy()->collection_set(); 2630 while (r != NULL) { 2631 HeapRegion* next = r->next_in_collection_set(); 2632 if (cl->doHeapRegion(r)) { 2633 cl->incomplete(); 2634 return; 2635 } 2636 r = next; 2637 } 2638 } 2639 2640 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r, 2641 HeapRegionClosure *cl) { 2642 if (r == NULL) { 2643 // The CSet is empty so there's nothing to do. 2644 return; 2645 } 2646 2647 assert(r->in_collection_set(), 2648 "Start region must be a member of the collection set."); 2649 HeapRegion* cur = r; 2650 while (cur != NULL) { 2651 HeapRegion* next = cur->next_in_collection_set(); 2652 if (cl->doHeapRegion(cur) && false) { 2653 cl->incomplete(); 2654 return; 2655 } 2656 cur = next; 2657 } 2658 cur = g1_policy()->collection_set(); 2659 while (cur != r) { 2660 HeapRegion* next = cur->next_in_collection_set(); 2661 if (cl->doHeapRegion(cur) && false) { 2662 cl->incomplete(); 2663 return; 2664 } 2665 cur = next; 2666 } 2667 } 2668 2669 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const { 2670 HeapRegion* result = _hrm.next_region_in_heap(from); 2671 while (result != NULL && result->is_humongous()) { 2672 result = _hrm.next_region_in_heap(result); 2673 } 2674 return result; 2675 } 2676 2677 Space* G1CollectedHeap::space_containing(const void* addr) const { 2678 return heap_region_containing(addr); 2679 } 2680 2681 HeapWord* G1CollectedHeap::block_start(const void* addr) const { 2682 Space* sp = space_containing(addr); 2683 return sp->block_start(addr); 2684 } 2685 2686 size_t G1CollectedHeap::block_size(const HeapWord* addr) const { 2687 Space* sp = space_containing(addr); 2688 return sp->block_size(addr); 2689 } 2690 2691 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { 2692 Space* sp = space_containing(addr); 2693 return sp->block_is_obj(addr); 2694 } 2695 2696 bool G1CollectedHeap::supports_tlab_allocation() const { 2697 return true; 2698 } 2699 2700 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { 2701 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes; 2702 } 2703 2704 size_t G1CollectedHeap::tlab_used(Thread* ignored) const { 2705 return young_list()->eden_used_bytes(); 2706 } 2707 2708 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size 2709 // must be smaller than the humongous object limit. 2710 size_t G1CollectedHeap::max_tlab_size() const { 2711 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment); 2712 } 2713 2714 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { 2715 // Return the remaining space in the cur alloc region, but not less than 2716 // the min TLAB size. 2717 2718 // Also, this value can be at most the humongous object threshold, 2719 // since we can't allow tlabs to grow big enough to accommodate 2720 // humongous objects. 2721 2722 HeapRegion* hr = _allocator->mutator_alloc_region(AllocationContext::current())->get(); 2723 size_t max_tlab = max_tlab_size() * wordSize; 2724 if (hr == NULL) { 2725 return max_tlab; 2726 } else { 2727 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab); 2728 } 2729 } 2730 2731 size_t G1CollectedHeap::max_capacity() const { 2732 return _hrm.reserved().byte_size(); 2733 } 2734 2735 jlong G1CollectedHeap::millis_since_last_gc() { 2736 // assert(false, "NYI"); 2737 return 0; 2738 } 2739 2740 void G1CollectedHeap::prepare_for_verify() { 2741 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) { 2742 ensure_parsability(false); 2743 } 2744 g1_rem_set()->prepare_for_verify(); 2745 } 2746 2747 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr, 2748 VerifyOption vo) { 2749 switch (vo) { 2750 case VerifyOption_G1UsePrevMarking: 2751 return hr->obj_allocated_since_prev_marking(obj); 2752 case VerifyOption_G1UseNextMarking: 2753 return hr->obj_allocated_since_next_marking(obj); 2754 case VerifyOption_G1UseMarkWord: 2755 return false; 2756 default: 2757 ShouldNotReachHere(); 2758 } 2759 return false; // keep some compilers happy 2760 } 2761 2762 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) { 2763 switch (vo) { 2764 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start(); 2765 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start(); 2766 case VerifyOption_G1UseMarkWord: return NULL; 2767 default: ShouldNotReachHere(); 2768 } 2769 return NULL; // keep some compilers happy 2770 } 2771 2772 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) { 2773 switch (vo) { 2774 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj); 2775 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj); 2776 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked(); 2777 default: ShouldNotReachHere(); 2778 } 2779 return false; // keep some compilers happy 2780 } 2781 2782 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) { 2783 switch (vo) { 2784 case VerifyOption_G1UsePrevMarking: return "PTAMS"; 2785 case VerifyOption_G1UseNextMarking: return "NTAMS"; 2786 case VerifyOption_G1UseMarkWord: return "NONE"; 2787 default: ShouldNotReachHere(); 2788 } 2789 return NULL; // keep some compilers happy 2790 } 2791 2792 class VerifyRootsClosure: public OopClosure { 2793 private: 2794 G1CollectedHeap* _g1h; 2795 VerifyOption _vo; 2796 bool _failures; 2797 public: 2798 // _vo == UsePrevMarking -> use "prev" marking information, 2799 // _vo == UseNextMarking -> use "next" marking information, 2800 // _vo == UseMarkWord -> use mark word from object header. 2801 VerifyRootsClosure(VerifyOption vo) : 2802 _g1h(G1CollectedHeap::heap()), 2803 _vo(vo), 2804 _failures(false) { } 2805 2806 bool failures() { return _failures; } 2807 2808 template <class T> void do_oop_nv(T* p) { 2809 T heap_oop = oopDesc::load_heap_oop(p); 2810 if (!oopDesc::is_null(heap_oop)) { 2811 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 2812 if (_g1h->is_obj_dead_cond(obj, _vo)) { 2813 gclog_or_tty->print_cr("Root location "PTR_FORMAT" " 2814 "points to dead obj "PTR_FORMAT, p, (void*) obj); 2815 if (_vo == VerifyOption_G1UseMarkWord) { 2816 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark())); 2817 } 2818 obj->print_on(gclog_or_tty); 2819 _failures = true; 2820 } 2821 } 2822 } 2823 2824 void do_oop(oop* p) { do_oop_nv(p); } 2825 void do_oop(narrowOop* p) { do_oop_nv(p); } 2826 }; 2827 2828 class G1VerifyCodeRootOopClosure: public OopClosure { 2829 G1CollectedHeap* _g1h; 2830 OopClosure* _root_cl; 2831 nmethod* _nm; 2832 VerifyOption _vo; 2833 bool _failures; 2834 2835 template <class T> void do_oop_work(T* p) { 2836 // First verify that this root is live 2837 _root_cl->do_oop(p); 2838 2839 if (!G1VerifyHeapRegionCodeRoots) { 2840 // We're not verifying the code roots attached to heap region. 2841 return; 2842 } 2843 2844 // Don't check the code roots during marking verification in a full GC 2845 if (_vo == VerifyOption_G1UseMarkWord) { 2846 return; 2847 } 2848 2849 // Now verify that the current nmethod (which contains p) is 2850 // in the code root list of the heap region containing the 2851 // object referenced by p. 2852 2853 T heap_oop = oopDesc::load_heap_oop(p); 2854 if (!oopDesc::is_null(heap_oop)) { 2855 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 2856 2857 // Now fetch the region containing the object 2858 HeapRegion* hr = _g1h->heap_region_containing(obj); 2859 HeapRegionRemSet* hrrs = hr->rem_set(); 2860 // Verify that the strong code root list for this region 2861 // contains the nmethod 2862 if (!hrrs->strong_code_roots_list_contains(_nm)) { 2863 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" " 2864 "from nmethod "PTR_FORMAT" not in strong " 2865 "code roots for region ["PTR_FORMAT","PTR_FORMAT")", 2866 p, _nm, hr->bottom(), hr->end()); 2867 _failures = true; 2868 } 2869 } 2870 } 2871 2872 public: 2873 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo): 2874 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {} 2875 2876 void do_oop(oop* p) { do_oop_work(p); } 2877 void do_oop(narrowOop* p) { do_oop_work(p); } 2878 2879 void set_nmethod(nmethod* nm) { _nm = nm; } 2880 bool failures() { return _failures; } 2881 }; 2882 2883 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure { 2884 G1VerifyCodeRootOopClosure* _oop_cl; 2885 2886 public: 2887 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl): 2888 _oop_cl(oop_cl) {} 2889 2890 void do_code_blob(CodeBlob* cb) { 2891 nmethod* nm = cb->as_nmethod_or_null(); 2892 if (nm != NULL) { 2893 _oop_cl->set_nmethod(nm); 2894 nm->oops_do(_oop_cl); 2895 } 2896 } 2897 }; 2898 2899 class YoungRefCounterClosure : public OopClosure { 2900 G1CollectedHeap* _g1h; 2901 int _count; 2902 public: 2903 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {} 2904 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } } 2905 void do_oop(narrowOop* p) { ShouldNotReachHere(); } 2906 2907 int count() { return _count; } 2908 void reset_count() { _count = 0; }; 2909 }; 2910 2911 class VerifyKlassClosure: public KlassClosure { 2912 YoungRefCounterClosure _young_ref_counter_closure; 2913 OopClosure *_oop_closure; 2914 public: 2915 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {} 2916 void do_klass(Klass* k) { 2917 k->oops_do(_oop_closure); 2918 2919 _young_ref_counter_closure.reset_count(); 2920 k->oops_do(&_young_ref_counter_closure); 2921 if (_young_ref_counter_closure.count() > 0) { 2922 guarantee(k->has_modified_oops(), err_msg("Klass " PTR_FORMAT ", has young refs but is not dirty.", k)); 2923 } 2924 } 2925 }; 2926 2927 class VerifyLivenessOopClosure: public OopClosure { 2928 G1CollectedHeap* _g1h; 2929 VerifyOption _vo; 2930 public: 2931 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo): 2932 _g1h(g1h), _vo(vo) 2933 { } 2934 void do_oop(narrowOop *p) { do_oop_work(p); } 2935 void do_oop( oop *p) { do_oop_work(p); } 2936 2937 template <class T> void do_oop_work(T *p) { 2938 oop obj = oopDesc::load_decode_heap_oop(p); 2939 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo), 2940 "Dead object referenced by a not dead object"); 2941 } 2942 }; 2943 2944 class VerifyObjsInRegionClosure: public ObjectClosure { 2945 private: 2946 G1CollectedHeap* _g1h; 2947 size_t _live_bytes; 2948 HeapRegion *_hr; 2949 VerifyOption _vo; 2950 public: 2951 // _vo == UsePrevMarking -> use "prev" marking information, 2952 // _vo == UseNextMarking -> use "next" marking information, 2953 // _vo == UseMarkWord -> use mark word from object header. 2954 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo) 2955 : _live_bytes(0), _hr(hr), _vo(vo) { 2956 _g1h = G1CollectedHeap::heap(); 2957 } 2958 void do_object(oop o) { 2959 VerifyLivenessOopClosure isLive(_g1h, _vo); 2960 assert(o != NULL, "Huh?"); 2961 if (!_g1h->is_obj_dead_cond(o, _vo)) { 2962 // If the object is alive according to the mark word, 2963 // then verify that the marking information agrees. 2964 // Note we can't verify the contra-positive of the 2965 // above: if the object is dead (according to the mark 2966 // word), it may not be marked, or may have been marked 2967 // but has since became dead, or may have been allocated 2968 // since the last marking. 2969 if (_vo == VerifyOption_G1UseMarkWord) { 2970 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch"); 2971 } 2972 2973 o->oop_iterate_no_header(&isLive); 2974 if (!_hr->obj_allocated_since_prev_marking(o)) { 2975 size_t obj_size = o->size(); // Make sure we don't overflow 2976 _live_bytes += (obj_size * HeapWordSize); 2977 } 2978 } 2979 } 2980 size_t live_bytes() { return _live_bytes; } 2981 }; 2982 2983 class PrintObjsInRegionClosure : public ObjectClosure { 2984 HeapRegion *_hr; 2985 G1CollectedHeap *_g1; 2986 public: 2987 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) { 2988 _g1 = G1CollectedHeap::heap(); 2989 }; 2990 2991 void do_object(oop o) { 2992 if (o != NULL) { 2993 HeapWord *start = (HeapWord *) o; 2994 size_t word_sz = o->size(); 2995 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT 2996 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n", 2997 (void*) o, word_sz, 2998 _g1->isMarkedPrev(o), 2999 _g1->isMarkedNext(o), 3000 _hr->obj_allocated_since_prev_marking(o)); 3001 HeapWord *end = start + word_sz; 3002 HeapWord *cur; 3003 int *val; 3004 for (cur = start; cur < end; cur++) { 3005 val = (int *) cur; 3006 gclog_or_tty->print("\t "PTR_FORMAT":%d\n", val, *val); 3007 } 3008 } 3009 } 3010 }; 3011 3012 class VerifyRegionClosure: public HeapRegionClosure { 3013 private: 3014 bool _par; 3015 VerifyOption _vo; 3016 bool _failures; 3017 public: 3018 // _vo == UsePrevMarking -> use "prev" marking information, 3019 // _vo == UseNextMarking -> use "next" marking information, 3020 // _vo == UseMarkWord -> use mark word from object header. 3021 VerifyRegionClosure(bool par, VerifyOption vo) 3022 : _par(par), 3023 _vo(vo), 3024 _failures(false) {} 3025 3026 bool failures() { 3027 return _failures; 3028 } 3029 3030 bool doHeapRegion(HeapRegion* r) { 3031 if (!r->is_continues_humongous()) { 3032 bool failures = false; 3033 r->verify(_vo, &failures); 3034 if (failures) { 3035 _failures = true; 3036 } else { 3037 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo); 3038 r->object_iterate(¬_dead_yet_cl); 3039 if (_vo != VerifyOption_G1UseNextMarking) { 3040 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) { 3041 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] " 3042 "max_live_bytes "SIZE_FORMAT" " 3043 "< calculated "SIZE_FORMAT, 3044 r->bottom(), r->end(), 3045 r->max_live_bytes(), 3046 not_dead_yet_cl.live_bytes()); 3047 _failures = true; 3048 } 3049 } else { 3050 // When vo == UseNextMarking we cannot currently do a sanity 3051 // check on the live bytes as the calculation has not been 3052 // finalized yet. 3053 } 3054 } 3055 } 3056 return false; // stop the region iteration if we hit a failure 3057 } 3058 }; 3059 3060 // This is the task used for parallel verification of the heap regions 3061 3062 class G1ParVerifyTask: public AbstractGangTask { 3063 private: 3064 G1CollectedHeap* _g1h; 3065 VerifyOption _vo; 3066 bool _failures; 3067 HeapRegionClaimer _hrclaimer; 3068 3069 public: 3070 // _vo == UsePrevMarking -> use "prev" marking information, 3071 // _vo == UseNextMarking -> use "next" marking information, 3072 // _vo == UseMarkWord -> use mark word from object header. 3073 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) : 3074 AbstractGangTask("Parallel verify task"), 3075 _g1h(g1h), 3076 _vo(vo), 3077 _failures(false), 3078 _hrclaimer(g1h->workers()->active_workers()) {} 3079 3080 bool failures() { 3081 return _failures; 3082 } 3083 3084 void work(uint worker_id) { 3085 HandleMark hm; 3086 VerifyRegionClosure blk(true, _vo); 3087 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer); 3088 if (blk.failures()) { 3089 _failures = true; 3090 } 3091 } 3092 }; 3093 3094 void G1CollectedHeap::verify(bool silent, VerifyOption vo) { 3095 if (SafepointSynchronize::is_at_safepoint()) { 3096 assert(Thread::current()->is_VM_thread(), 3097 "Expected to be executed serially by the VM thread at this point"); 3098 3099 if (!silent) { gclog_or_tty->print("Roots "); } 3100 VerifyRootsClosure rootsCl(vo); 3101 VerifyKlassClosure klassCl(this, &rootsCl); 3102 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false); 3103 3104 // We apply the relevant closures to all the oops in the 3105 // system dictionary, class loader data graph, the string table 3106 // and the nmethods in the code cache. 3107 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo); 3108 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl); 3109 3110 process_all_roots(true, // activate StrongRootsScope 3111 SO_AllCodeCache, // roots scanning options 3112 &rootsCl, 3113 &cldCl, 3114 &blobsCl); 3115 3116 bool failures = rootsCl.failures() || codeRootsCl.failures(); 3117 3118 if (vo != VerifyOption_G1UseMarkWord) { 3119 // If we're verifying during a full GC then the region sets 3120 // will have been torn down at the start of the GC. Therefore 3121 // verifying the region sets will fail. So we only verify 3122 // the region sets when not in a full GC. 3123 if (!silent) { gclog_or_tty->print("HeapRegionSets "); } 3124 verify_region_sets(); 3125 } 3126 3127 if (!silent) { gclog_or_tty->print("HeapRegions "); } 3128 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) { 3129 3130 G1ParVerifyTask task(this, vo); 3131 assert(UseDynamicNumberOfGCThreads || 3132 workers()->active_workers() == workers()->total_workers(), 3133 "If not dynamic should be using all the workers"); 3134 int n_workers = workers()->active_workers(); 3135 set_par_threads(n_workers); 3136 workers()->run_task(&task); 3137 set_par_threads(0); 3138 if (task.failures()) { 3139 failures = true; 3140 } 3141 3142 } else { 3143 VerifyRegionClosure blk(false, vo); 3144 heap_region_iterate(&blk); 3145 if (blk.failures()) { 3146 failures = true; 3147 } 3148 } 3149 3150 if (G1StringDedup::is_enabled()) { 3151 if (!silent) gclog_or_tty->print("StrDedup "); 3152 G1StringDedup::verify(); 3153 } 3154 3155 if (failures) { 3156 gclog_or_tty->print_cr("Heap:"); 3157 // It helps to have the per-region information in the output to 3158 // help us track down what went wrong. This is why we call 3159 // print_extended_on() instead of print_on(). 3160 print_extended_on(gclog_or_tty); 3161 gclog_or_tty->cr(); 3162 #ifndef PRODUCT 3163 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) { 3164 concurrent_mark()->print_reachable("at-verification-failure", 3165 vo, false /* all */); 3166 } 3167 #endif 3168 gclog_or_tty->flush(); 3169 } 3170 guarantee(!failures, "there should not have been any failures"); 3171 } else { 3172 if (!silent) { 3173 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet"); 3174 if (G1StringDedup::is_enabled()) { 3175 gclog_or_tty->print(", StrDedup"); 3176 } 3177 gclog_or_tty->print(") "); 3178 } 3179 } 3180 } 3181 3182 void G1CollectedHeap::verify(bool silent) { 3183 verify(silent, VerifyOption_G1UsePrevMarking); 3184 } 3185 3186 double G1CollectedHeap::verify(bool guard, const char* msg) { 3187 double verify_time_ms = 0.0; 3188 3189 if (guard && total_collections() >= VerifyGCStartAt) { 3190 double verify_start = os::elapsedTime(); 3191 HandleMark hm; // Discard invalid handles created during verification 3192 prepare_for_verify(); 3193 Universe::verify(VerifyOption_G1UsePrevMarking, msg); 3194 verify_time_ms = (os::elapsedTime() - verify_start) * 1000; 3195 } 3196 3197 return verify_time_ms; 3198 } 3199 3200 void G1CollectedHeap::verify_before_gc() { 3201 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:"); 3202 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms); 3203 } 3204 3205 void G1CollectedHeap::verify_after_gc() { 3206 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:"); 3207 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms); 3208 } 3209 3210 class PrintRegionClosure: public HeapRegionClosure { 3211 outputStream* _st; 3212 public: 3213 PrintRegionClosure(outputStream* st) : _st(st) {} 3214 bool doHeapRegion(HeapRegion* r) { 3215 r->print_on(_st); 3216 return false; 3217 } 3218 }; 3219 3220 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 3221 const HeapRegion* hr, 3222 const VerifyOption vo) const { 3223 switch (vo) { 3224 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); 3225 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); 3226 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked(); 3227 default: ShouldNotReachHere(); 3228 } 3229 return false; // keep some compilers happy 3230 } 3231 3232 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 3233 const VerifyOption vo) const { 3234 switch (vo) { 3235 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); 3236 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); 3237 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked(); 3238 default: ShouldNotReachHere(); 3239 } 3240 return false; // keep some compilers happy 3241 } 3242 3243 void G1CollectedHeap::print_on(outputStream* st) const { 3244 st->print(" %-20s", "garbage-first heap"); 3245 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 3246 capacity()/K, used_unlocked()/K); 3247 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")", 3248 _hrm.reserved().start(), 3249 _hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords, 3250 _hrm.reserved().end()); 3251 st->cr(); 3252 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); 3253 uint young_regions = _young_list->length(); 3254 st->print("%u young (" SIZE_FORMAT "K), ", young_regions, 3255 (size_t) young_regions * HeapRegion::GrainBytes / K); 3256 uint survivor_regions = g1_policy()->recorded_survivor_regions(); 3257 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, 3258 (size_t) survivor_regions * HeapRegion::GrainBytes / K); 3259 st->cr(); 3260 MetaspaceAux::print_on(st); 3261 } 3262 3263 void G1CollectedHeap::print_extended_on(outputStream* st) const { 3264 print_on(st); 3265 3266 // Print the per-region information. 3267 st->cr(); 3268 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), " 3269 "HS=humongous(starts), HC=humongous(continues), " 3270 "CS=collection set, F=free, TS=gc time stamp, " 3271 "PTAMS=previous top-at-mark-start, " 3272 "NTAMS=next top-at-mark-start)"); 3273 PrintRegionClosure blk(st); 3274 heap_region_iterate(&blk); 3275 } 3276 3277 void G1CollectedHeap::print_on_error(outputStream* st) const { 3278 this->CollectedHeap::print_on_error(st); 3279 3280 if (_cm != NULL) { 3281 st->cr(); 3282 _cm->print_on_error(st); 3283 } 3284 } 3285 3286 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const { 3287 workers()->print_worker_threads_on(st); 3288 _cmThread->print_on(st); 3289 st->cr(); 3290 _cm->print_worker_threads_on(st); 3291 _cg1r->print_worker_threads_on(st); 3292 if (G1StringDedup::is_enabled()) { 3293 G1StringDedup::print_worker_threads_on(st); 3294 } 3295 } 3296 3297 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { 3298 workers()->threads_do(tc); 3299 tc->do_thread(_cmThread); 3300 _cg1r->threads_do(tc); 3301 if (G1StringDedup::is_enabled()) { 3302 G1StringDedup::threads_do(tc); 3303 } 3304 } 3305 3306 void G1CollectedHeap::print_tracing_info() const { 3307 // We'll overload this to mean "trace GC pause statistics." 3308 if (TraceYoungGenTime || TraceOldGenTime) { 3309 // The "G1CollectorPolicy" is keeping track of these stats, so delegate 3310 // to that. 3311 g1_policy()->print_tracing_info(); 3312 } 3313 if (G1SummarizeRSetStats) { 3314 g1_rem_set()->print_summary_info(); 3315 } 3316 if (G1SummarizeConcMark) { 3317 concurrent_mark()->print_summary_info(); 3318 } 3319 g1_policy()->print_yg_surv_rate_info(); 3320 } 3321 3322 #ifndef PRODUCT 3323 // Helpful for debugging RSet issues. 3324 3325 class PrintRSetsClosure : public HeapRegionClosure { 3326 private: 3327 const char* _msg; 3328 size_t _occupied_sum; 3329 3330 public: 3331 bool doHeapRegion(HeapRegion* r) { 3332 HeapRegionRemSet* hrrs = r->rem_set(); 3333 size_t occupied = hrrs->occupied(); 3334 _occupied_sum += occupied; 3335 3336 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT, 3337 HR_FORMAT_PARAMS(r)); 3338 if (occupied == 0) { 3339 gclog_or_tty->print_cr(" RSet is empty"); 3340 } else { 3341 hrrs->print(); 3342 } 3343 gclog_or_tty->print_cr("----------"); 3344 return false; 3345 } 3346 3347 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { 3348 gclog_or_tty->cr(); 3349 gclog_or_tty->print_cr("========================================"); 3350 gclog_or_tty->print_cr("%s", msg); 3351 gclog_or_tty->cr(); 3352 } 3353 3354 ~PrintRSetsClosure() { 3355 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum); 3356 gclog_or_tty->print_cr("========================================"); 3357 gclog_or_tty->cr(); 3358 } 3359 }; 3360 3361 void G1CollectedHeap::print_cset_rsets() { 3362 PrintRSetsClosure cl("Printing CSet RSets"); 3363 collection_set_iterate(&cl); 3364 } 3365 3366 void G1CollectedHeap::print_all_rsets() { 3367 PrintRSetsClosure cl("Printing All RSets");; 3368 heap_region_iterate(&cl); 3369 } 3370 #endif // PRODUCT 3371 3372 G1CollectedHeap* G1CollectedHeap::heap() { 3373 assert(_sh->kind() == CollectedHeap::G1CollectedHeap, 3374 "not a garbage-first heap"); 3375 return _g1h; 3376 } 3377 3378 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) { 3379 // always_do_update_barrier = false; 3380 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 3381 // Fill TLAB's and such 3382 accumulate_statistics_all_tlabs(); 3383 ensure_parsability(true); 3384 3385 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) && 3386 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) { 3387 g1_rem_set()->print_periodic_summary_info("Before GC RS summary"); 3388 } 3389 } 3390 3391 void G1CollectedHeap::gc_epilogue(bool full) { 3392 3393 if (G1SummarizeRSetStats && 3394 (G1SummarizeRSetStatsPeriod > 0) && 3395 // we are at the end of the GC. Total collections has already been increased. 3396 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) { 3397 g1_rem_set()->print_periodic_summary_info("After GC RS summary"); 3398 } 3399 3400 // FIXME: what is this about? 3401 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" 3402 // is set. 3403 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(), 3404 "derived pointer present")); 3405 // always_do_update_barrier = true; 3406 3407 resize_all_tlabs(); 3408 allocation_context_stats().update(full); 3409 3410 // We have just completed a GC. Update the soft reference 3411 // policy with the new heap occupancy 3412 Universe::update_heap_info_at_gc(); 3413 } 3414 3415 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, 3416 uint gc_count_before, 3417 bool* succeeded, 3418 GCCause::Cause gc_cause) { 3419 assert_heap_not_locked_and_not_at_safepoint(); 3420 g1_policy()->record_stop_world_start(); 3421 VM_G1IncCollectionPause op(gc_count_before, 3422 word_size, 3423 false, /* should_initiate_conc_mark */ 3424 g1_policy()->max_pause_time_ms(), 3425 gc_cause); 3426 3427 op.set_allocation_context(AllocationContext::current()); 3428 VMThread::execute(&op); 3429 3430 HeapWord* result = op.result(); 3431 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded(); 3432 assert(result == NULL || ret_succeeded, 3433 "the result should be NULL if the VM did not succeed"); 3434 *succeeded = ret_succeeded; 3435 3436 assert_heap_not_locked(); 3437 return result; 3438 } 3439 3440 void 3441 G1CollectedHeap::doConcurrentMark() { 3442 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); 3443 if (!_cmThread->in_progress()) { 3444 _cmThread->set_started(); 3445 CGC_lock->notify(); 3446 } 3447 } 3448 3449 size_t G1CollectedHeap::pending_card_num() { 3450 size_t extra_cards = 0; 3451 JavaThread *curr = Threads::first(); 3452 while (curr != NULL) { 3453 DirtyCardQueue& dcq = curr->dirty_card_queue(); 3454 extra_cards += dcq.size(); 3455 curr = curr->next(); 3456 } 3457 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 3458 size_t buffer_size = dcqs.buffer_size(); 3459 size_t buffer_num = dcqs.completed_buffers_num(); 3460 3461 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes 3462 // in bytes - not the number of 'entries'. We need to convert 3463 // into a number of cards. 3464 return (buffer_size * buffer_num + extra_cards) / oopSize; 3465 } 3466 3467 size_t G1CollectedHeap::cards_scanned() { 3468 return g1_rem_set()->cardsScanned(); 3469 } 3470 3471 bool G1CollectedHeap::humongous_region_is_always_live(uint index) { 3472 HeapRegion* region = region_at(index); 3473 assert(region->is_starts_humongous(), "Must start a humongous object"); 3474 return oop(region->bottom())->is_objArray() || !region->rem_set()->is_empty(); 3475 } 3476 3477 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure { 3478 private: 3479 size_t _total_humongous; 3480 size_t _candidate_humongous; 3481 3482 DirtyCardQueue _dcq; 3483 3484 bool humongous_region_is_candidate(uint index) { 3485 HeapRegion* region = G1CollectedHeap::heap()->region_at(index); 3486 assert(region->is_starts_humongous(), "Must start a humongous object"); 3487 HeapRegionRemSet* const rset = region->rem_set(); 3488 bool const allow_stale_refs = G1EagerReclaimHumongousObjectsWithStaleRefs; 3489 return !oop(region->bottom())->is_objArray() && 3490 ((allow_stale_refs && rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)) || 3491 (!allow_stale_refs && rset->is_empty())); 3492 } 3493 3494 public: 3495 RegisterHumongousWithInCSetFastTestClosure() 3496 : _total_humongous(0), 3497 _candidate_humongous(0), 3498 _dcq(&JavaThread::dirty_card_queue_set()) { 3499 } 3500 3501 virtual bool doHeapRegion(HeapRegion* r) { 3502 if (!r->is_starts_humongous()) { 3503 return false; 3504 } 3505 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 3506 3507 uint region_idx = r->hrm_index(); 3508 bool is_candidate = humongous_region_is_candidate(region_idx); 3509 // Is_candidate already filters out humongous object with large remembered sets. 3510 // If we have a humongous object with a few remembered sets, we simply flush these 3511 // remembered set entries into the DCQS. That will result in automatic 3512 // re-evaluation of their remembered set entries during the following evacuation 3513 // phase. 3514 if (is_candidate) { 3515 if (!r->rem_set()->is_empty()) { 3516 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries), 3517 "Found a not-small remembered set here. This is inconsistent with previous assumptions."); 3518 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set(); 3519 HeapRegionRemSetIterator hrrs(r->rem_set()); 3520 size_t card_index; 3521 while (hrrs.has_next(card_index)) { 3522 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index); 3523 // The remembered set might contain references to already freed 3524 // regions. Filter out such entries to avoid failing card table 3525 // verification. 3526 if (!g1h->heap_region_containing(bs->addr_for(card_ptr))->is_free()) { 3527 if (*card_ptr != CardTableModRefBS::dirty_card_val()) { 3528 *card_ptr = CardTableModRefBS::dirty_card_val(); 3529 _dcq.enqueue(card_ptr); 3530 } 3531 } 3532 } 3533 r->rem_set()->clear_locked(); 3534 } 3535 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty."); 3536 g1h->register_humongous_region_with_cset(region_idx); 3537 _candidate_humongous++; 3538 } 3539 _total_humongous++; 3540 3541 return false; 3542 } 3543 3544 size_t total_humongous() const { return _total_humongous; } 3545 size_t candidate_humongous() const { return _candidate_humongous; } 3546 3547 void flush_rem_set_entries() { _dcq.flush(); } 3548 }; 3549 3550 void G1CollectedHeap::register_humongous_regions_with_cset() { 3551 if (!G1EagerReclaimHumongousObjects) { 3552 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0); 3553 return; 3554 } 3555 double time = os::elapsed_counter(); 3556 3557 RegisterHumongousWithInCSetFastTestClosure cl; 3558 heap_region_iterate(&cl); 3559 3560 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0; 3561 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time, 3562 cl.total_humongous(), 3563 cl.candidate_humongous()); 3564 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0; 3565 3566 if (_has_humongous_reclaim_candidates || G1TraceEagerReclaimHumongousObjects) { 3567 clear_humongous_is_live_table(); 3568 } 3569 3570 // Finally flush all remembered set entries to re-check into the global DCQS. 3571 cl.flush_rem_set_entries(); 3572 } 3573 3574 void 3575 G1CollectedHeap::setup_surviving_young_words() { 3576 assert(_surviving_young_words == NULL, "pre-condition"); 3577 uint array_length = g1_policy()->young_cset_region_length(); 3578 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC); 3579 if (_surviving_young_words == NULL) { 3580 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR, 3581 "Not enough space for young surv words summary."); 3582 } 3583 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t)); 3584 #ifdef ASSERT 3585 for (uint i = 0; i < array_length; ++i) { 3586 assert( _surviving_young_words[i] == 0, "memset above" ); 3587 } 3588 #endif // !ASSERT 3589 } 3590 3591 void 3592 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) { 3593 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); 3594 uint array_length = g1_policy()->young_cset_region_length(); 3595 for (uint i = 0; i < array_length; ++i) { 3596 _surviving_young_words[i] += surv_young_words[i]; 3597 } 3598 } 3599 3600 void 3601 G1CollectedHeap::cleanup_surviving_young_words() { 3602 guarantee( _surviving_young_words != NULL, "pre-condition" ); 3603 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words); 3604 _surviving_young_words = NULL; 3605 } 3606 3607 #ifdef ASSERT 3608 class VerifyCSetClosure: public HeapRegionClosure { 3609 public: 3610 bool doHeapRegion(HeapRegion* hr) { 3611 // Here we check that the CSet region's RSet is ready for parallel 3612 // iteration. The fields that we'll verify are only manipulated 3613 // when the region is part of a CSet and is collected. Afterwards, 3614 // we reset these fields when we clear the region's RSet (when the 3615 // region is freed) so they are ready when the region is 3616 // re-allocated. The only exception to this is if there's an 3617 // evacuation failure and instead of freeing the region we leave 3618 // it in the heap. In that case, we reset these fields during 3619 // evacuation failure handling. 3620 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification"); 3621 3622 // Here's a good place to add any other checks we'd like to 3623 // perform on CSet regions. 3624 return false; 3625 } 3626 }; 3627 #endif // ASSERT 3628 3629 #if TASKQUEUE_STATS 3630 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) { 3631 st->print_raw_cr("GC Task Stats"); 3632 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); 3633 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); 3634 } 3635 3636 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const { 3637 print_taskqueue_stats_hdr(st); 3638 3639 TaskQueueStats totals; 3640 const int n = workers()->total_workers(); 3641 for (int i = 0; i < n; ++i) { 3642 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr(); 3643 totals += task_queue(i)->stats; 3644 } 3645 st->print_raw("tot "); totals.print(st); st->cr(); 3646 3647 DEBUG_ONLY(totals.verify()); 3648 } 3649 3650 void G1CollectedHeap::reset_taskqueue_stats() { 3651 const int n = workers()->total_workers(); 3652 for (int i = 0; i < n; ++i) { 3653 task_queue(i)->stats.reset(); 3654 } 3655 } 3656 #endif // TASKQUEUE_STATS 3657 3658 void G1CollectedHeap::log_gc_header() { 3659 if (!G1Log::fine()) { 3660 return; 3661 } 3662 3663 gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id()); 3664 3665 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause()) 3666 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)") 3667 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : ""); 3668 3669 gclog_or_tty->print("[%s", (const char*)gc_cause_str); 3670 } 3671 3672 void G1CollectedHeap::log_gc_footer(double pause_time_sec) { 3673 if (!G1Log::fine()) { 3674 return; 3675 } 3676 3677 if (G1Log::finer()) { 3678 if (evacuation_failed()) { 3679 gclog_or_tty->print(" (to-space exhausted)"); 3680 } 3681 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec); 3682 g1_policy()->phase_times()->note_gc_end(); 3683 g1_policy()->phase_times()->print(pause_time_sec); 3684 g1_policy()->print_detailed_heap_transition(); 3685 } else { 3686 if (evacuation_failed()) { 3687 gclog_or_tty->print("--"); 3688 } 3689 g1_policy()->print_heap_transition(); 3690 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec); 3691 } 3692 gclog_or_tty->flush(); 3693 } 3694 3695 bool 3696 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { 3697 assert_at_safepoint(true /* should_be_vm_thread */); 3698 guarantee(!is_gc_active(), "collection is not reentrant"); 3699 3700 if (GC_locker::check_active_before_gc()) { 3701 return false; 3702 } 3703 3704 _gc_timer_stw->register_gc_start(); 3705 3706 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start()); 3707 3708 SvcGCMarker sgcm(SvcGCMarker::MINOR); 3709 ResourceMark rm; 3710 3711 print_heap_before_gc(); 3712 trace_heap_before_gc(_gc_tracer_stw); 3713 3714 verify_region_sets_optional(); 3715 verify_dirty_young_regions(); 3716 3717 // This call will decide whether this pause is an initial-mark 3718 // pause. If it is, during_initial_mark_pause() will return true 3719 // for the duration of this pause. 3720 g1_policy()->decide_on_conc_mark_initiation(); 3721 3722 // We do not allow initial-mark to be piggy-backed on a mixed GC. 3723 assert(!g1_policy()->during_initial_mark_pause() || 3724 g1_policy()->gcs_are_young(), "sanity"); 3725 3726 // We also do not allow mixed GCs during marking. 3727 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity"); 3728 3729 // Record whether this pause is an initial mark. When the current 3730 // thread has completed its logging output and it's safe to signal 3731 // the CM thread, the flag's value in the policy has been reset. 3732 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause(); 3733 3734 // Inner scope for scope based logging, timers, and stats collection 3735 { 3736 EvacuationInfo evacuation_info; 3737 3738 if (g1_policy()->during_initial_mark_pause()) { 3739 // We are about to start a marking cycle, so we increment the 3740 // full collection counter. 3741 increment_old_marking_cycles_started(); 3742 register_concurrent_cycle_start(_gc_timer_stw->gc_start()); 3743 } 3744 3745 _gc_tracer_stw->report_yc_type(yc_type()); 3746 3747 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty); 3748 3749 uint active_workers = workers()->active_workers(); 3750 double pause_start_sec = os::elapsedTime(); 3751 g1_policy()->phase_times()->note_gc_start(active_workers, mark_in_progress()); 3752 log_gc_header(); 3753 3754 TraceCollectorStats tcs(g1mm()->incremental_collection_counters()); 3755 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause()); 3756 3757 // If the secondary_free_list is not empty, append it to the 3758 // free_list. No need to wait for the cleanup operation to finish; 3759 // the region allocation code will check the secondary_free_list 3760 // and wait if necessary. If the G1StressConcRegionFreeing flag is 3761 // set, skip this step so that the region allocation code has to 3762 // get entries from the secondary_free_list. 3763 if (!G1StressConcRegionFreeing) { 3764 append_secondary_free_list_if_not_empty_with_lock(); 3765 } 3766 3767 assert(check_young_list_well_formed(), "young list should be well formed"); 3768 3769 // Don't dynamically change the number of GC threads this early. A value of 3770 // 0 is used to indicate serial work. When parallel work is done, 3771 // it will be set. 3772 3773 { // Call to jvmpi::post_class_unload_events must occur outside of active GC 3774 IsGCActiveMark x; 3775 3776 gc_prologue(false); 3777 increment_total_collections(false /* full gc */); 3778 increment_gc_time_stamp(); 3779 3780 verify_before_gc(); 3781 3782 check_bitmaps("GC Start"); 3783 3784 COMPILER2_PRESENT(DerivedPointerTable::clear()); 3785 3786 // Please see comment in g1CollectedHeap.hpp and 3787 // G1CollectedHeap::ref_processing_init() to see how 3788 // reference processing currently works in G1. 3789 3790 // Enable discovery in the STW reference processor 3791 ref_processor_stw()->enable_discovery(); 3792 3793 { 3794 // We want to temporarily turn off discovery by the 3795 // CM ref processor, if necessary, and turn it back on 3796 // on again later if we do. Using a scoped 3797 // NoRefDiscovery object will do this. 3798 NoRefDiscovery no_cm_discovery(ref_processor_cm()); 3799 3800 // Forget the current alloc region (we might even choose it to be part 3801 // of the collection set!). 3802 _allocator->release_mutator_alloc_region(); 3803 3804 // We should call this after we retire the mutator alloc 3805 // region(s) so that all the ALLOC / RETIRE events are generated 3806 // before the start GC event. 3807 _hr_printer.start_gc(false /* full */, (size_t) total_collections()); 3808 3809 // This timing is only used by the ergonomics to handle our pause target. 3810 // It is unclear why this should not include the full pause. We will 3811 // investigate this in CR 7178365. 3812 // 3813 // Preserving the old comment here if that helps the investigation: 3814 // 3815 // The elapsed time induced by the start time below deliberately elides 3816 // the possible verification above. 3817 double sample_start_time_sec = os::elapsedTime(); 3818 3819 #if YOUNG_LIST_VERBOSE 3820 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:"); 3821 _young_list->print(); 3822 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 3823 #endif // YOUNG_LIST_VERBOSE 3824 3825 g1_policy()->record_collection_pause_start(sample_start_time_sec); 3826 3827 double scan_wait_start = os::elapsedTime(); 3828 // We have to wait until the CM threads finish scanning the 3829 // root regions as it's the only way to ensure that all the 3830 // objects on them have been correctly scanned before we start 3831 // moving them during the GC. 3832 bool waited = _cm->root_regions()->wait_until_scan_finished(); 3833 double wait_time_ms = 0.0; 3834 if (waited) { 3835 double scan_wait_end = os::elapsedTime(); 3836 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0; 3837 } 3838 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms); 3839 3840 #if YOUNG_LIST_VERBOSE 3841 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:"); 3842 _young_list->print(); 3843 #endif // YOUNG_LIST_VERBOSE 3844 3845 if (g1_policy()->during_initial_mark_pause()) { 3846 concurrent_mark()->checkpointRootsInitialPre(); 3847 } 3848 3849 #if YOUNG_LIST_VERBOSE 3850 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:"); 3851 _young_list->print(); 3852 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 3853 #endif // YOUNG_LIST_VERBOSE 3854 3855 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info); 3856 3857 register_humongous_regions_with_cset(); 3858 3859 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table."); 3860 3861 _cm->note_start_of_gc(); 3862 // We should not verify the per-thread SATB buffers given that 3863 // we have not filtered them yet (we'll do so during the 3864 // GC). We also call this after finalize_cset() to 3865 // ensure that the CSet has been finalized. 3866 _cm->verify_no_cset_oops(true /* verify_stacks */, 3867 true /* verify_enqueued_buffers */, 3868 false /* verify_thread_buffers */, 3869 true /* verify_fingers */); 3870 3871 if (_hr_printer.is_active()) { 3872 HeapRegion* hr = g1_policy()->collection_set(); 3873 while (hr != NULL) { 3874 _hr_printer.cset(hr); 3875 hr = hr->next_in_collection_set(); 3876 } 3877 } 3878 3879 #ifdef ASSERT 3880 VerifyCSetClosure cl; 3881 collection_set_iterate(&cl); 3882 #endif // ASSERT 3883 3884 setup_surviving_young_words(); 3885 3886 // Initialize the GC alloc regions. 3887 _allocator->init_gc_alloc_regions(evacuation_info); 3888 3889 // Actually do the work... 3890 evacuate_collection_set(evacuation_info); 3891 3892 // We do this to mainly verify the per-thread SATB buffers 3893 // (which have been filtered by now) since we didn't verify 3894 // them earlier. No point in re-checking the stacks / enqueued 3895 // buffers given that the CSet has not changed since last time 3896 // we checked. 3897 _cm->verify_no_cset_oops(false /* verify_stacks */, 3898 false /* verify_enqueued_buffers */, 3899 true /* verify_thread_buffers */, 3900 true /* verify_fingers */); 3901 3902 free_collection_set(g1_policy()->collection_set(), evacuation_info); 3903 3904 eagerly_reclaim_humongous_regions(); 3905 3906 g1_policy()->clear_collection_set(); 3907 3908 cleanup_surviving_young_words(); 3909 3910 // Start a new incremental collection set for the next pause. 3911 g1_policy()->start_incremental_cset_building(); 3912 3913 clear_cset_fast_test(); 3914 3915 _young_list->reset_sampled_info(); 3916 3917 // Don't check the whole heap at this point as the 3918 // GC alloc regions from this pause have been tagged 3919 // as survivors and moved on to the survivor list. 3920 // Survivor regions will fail the !is_young() check. 3921 assert(check_young_list_empty(false /* check_heap */), 3922 "young list should be empty"); 3923 3924 #if YOUNG_LIST_VERBOSE 3925 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:"); 3926 _young_list->print(); 3927 #endif // YOUNG_LIST_VERBOSE 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 _allocator->set_used(recalculate_used()); 3937 uint n_queues = MAX2((int)ParallelGCThreads, 1); 3938 for (uint i = 0; i < n_queues; i++) { 3939 if (_evacuation_failed_info_array[i].has_failed()) { 3940 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]); 3941 } 3942 } 3943 } else { 3944 // The "used" of the the collection set have already been subtracted 3945 // when they were freed. Add in the bytes evacuated. 3946 _allocator->increase_used(g1_policy()->bytes_copied_during_gc()); 3947 } 3948 3949 if (g1_policy()->during_initial_mark_pause()) { 3950 // We have to do this before we notify the CM threads that 3951 // they can start working to make sure that all the 3952 // appropriate initialization is done on the CM object. 3953 concurrent_mark()->checkpointRootsInitialPost(); 3954 set_marking_started(); 3955 // Note that we don't actually trigger the CM thread at 3956 // this point. We do that later when we're sure that 3957 // the current thread has completed its logging output. 3958 } 3959 3960 allocate_dummy_regions(); 3961 3962 #if YOUNG_LIST_VERBOSE 3963 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:"); 3964 _young_list->print(); 3965 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 3966 #endif // YOUNG_LIST_VERBOSE 3967 3968 _allocator->init_mutator_alloc_region(); 3969 3970 { 3971 size_t expand_bytes = g1_policy()->expansion_amount(); 3972 if (expand_bytes > 0) { 3973 size_t bytes_before = capacity(); 3974 // No need for an ergo verbose message here, 3975 // expansion_amount() does this when it returns a value > 0. 3976 if (!expand(expand_bytes)) { 3977 // We failed to expand the heap. Cannot do anything about it. 3978 } 3979 } 3980 } 3981 3982 // We redo the verification but now wrt to the new CSet which 3983 // has just got initialized after the previous CSet was freed. 3984 _cm->verify_no_cset_oops(true /* verify_stacks */, 3985 true /* verify_enqueued_buffers */, 3986 true /* verify_thread_buffers */, 3987 true /* verify_fingers */); 3988 _cm->note_end_of_gc(); 3989 3990 // This timing is only used by the ergonomics to handle our pause target. 3991 // It is unclear why this should not include the full pause. We will 3992 // investigate this in CR 7178365. 3993 double sample_end_time_sec = os::elapsedTime(); 3994 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; 3995 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info); 3996 3997 MemoryService::track_memory_usage(); 3998 3999 // In prepare_for_verify() below we'll need to scan the deferred 4000 // update buffers to bring the RSets up-to-date if 4001 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning 4002 // the update buffers we'll probably need to scan cards on the 4003 // regions we just allocated to (i.e., the GC alloc 4004 // regions). However, during the last GC we called 4005 // set_saved_mark() on all the GC alloc regions, so card 4006 // scanning might skip the [saved_mark_word()...top()] area of 4007 // those regions (i.e., the area we allocated objects into 4008 // during the last GC). But it shouldn't. Given that 4009 // saved_mark_word() is conditional on whether the GC time stamp 4010 // on the region is current or not, by incrementing the GC time 4011 // stamp here we invalidate all the GC time stamps on all the 4012 // regions and saved_mark_word() will simply return top() for 4013 // all the regions. This is a nicer way of ensuring this rather 4014 // than iterating over the regions and fixing them. In fact, the 4015 // GC time stamp increment here also ensures that 4016 // saved_mark_word() will return top() between pauses, i.e., 4017 // during concurrent refinement. So we don't need the 4018 // is_gc_active() check to decided which top to use when 4019 // scanning cards (see CR 7039627). 4020 increment_gc_time_stamp(); 4021 4022 verify_after_gc(); 4023 check_bitmaps("GC End"); 4024 4025 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 4026 ref_processor_stw()->verify_no_references_recorded(); 4027 4028 // CM reference discovery will be re-enabled if necessary. 4029 } 4030 4031 // We should do this after we potentially expand the heap so 4032 // that all the COMMIT events are generated before the end GC 4033 // event, and after we retire the GC alloc regions so that all 4034 // RETIRE events are generated before the end GC event. 4035 _hr_printer.end_gc(false /* full */, (size_t) total_collections()); 4036 4037 #ifdef TRACESPINNING 4038 ParallelTaskTerminator::print_termination_counts(); 4039 #endif 4040 4041 gc_epilogue(false); 4042 } 4043 4044 // Print the remainder of the GC log output. 4045 log_gc_footer(os::elapsedTime() - pause_start_sec); 4046 4047 // It is not yet to safe to tell the concurrent mark to 4048 // start as we have some optional output below. We don't want the 4049 // output from the concurrent mark thread interfering with this 4050 // logging output either. 4051 4052 _hrm.verify_optional(); 4053 verify_region_sets_optional(); 4054 4055 TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats()); 4056 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); 4057 4058 print_heap_after_gc(); 4059 trace_heap_after_gc(_gc_tracer_stw); 4060 4061 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 4062 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 4063 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 4064 // before any GC notifications are raised. 4065 g1mm()->update_sizes(); 4066 4067 _gc_tracer_stw->report_evacuation_info(&evacuation_info); 4068 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold()); 4069 _gc_timer_stw->register_gc_end(); 4070 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions()); 4071 } 4072 // It should now be safe to tell the concurrent mark thread to start 4073 // without its logging output interfering with the logging output 4074 // that came from the pause. 4075 4076 if (should_start_conc_mark) { 4077 // CAUTION: after the doConcurrentMark() call below, 4078 // the concurrent marking thread(s) could be running 4079 // concurrently with us. Make sure that anything after 4080 // this point does not assume that we are the only GC thread 4081 // running. Note: of course, the actual marking work will 4082 // not start until the safepoint itself is released in 4083 // SuspendibleThreadSet::desynchronize(). 4084 doConcurrentMark(); 4085 } 4086 4087 return true; 4088 } 4089 4090 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) { 4091 _drain_in_progress = false; 4092 set_evac_failure_closure(cl); 4093 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true); 4094 } 4095 4096 void G1CollectedHeap::finalize_for_evac_failure() { 4097 assert(_evac_failure_scan_stack != NULL && 4098 _evac_failure_scan_stack->length() == 0, 4099 "Postcondition"); 4100 assert(!_drain_in_progress, "Postcondition"); 4101 delete _evac_failure_scan_stack; 4102 _evac_failure_scan_stack = NULL; 4103 } 4104 4105 void G1CollectedHeap::remove_self_forwarding_pointers() { 4106 double remove_self_forwards_start = os::elapsedTime(); 4107 4108 set_par_threads(); 4109 G1ParRemoveSelfForwardPtrsTask rsfp_task(this); 4110 workers()->run_task(&rsfp_task); 4111 set_par_threads(0); 4112 4113 // Now restore saved marks, if any. 4114 assert(_objs_with_preserved_marks.size() == 4115 _preserved_marks_of_objs.size(), "Both or none."); 4116 while (!_objs_with_preserved_marks.is_empty()) { 4117 oop obj = _objs_with_preserved_marks.pop(); 4118 markOop m = _preserved_marks_of_objs.pop(); 4119 obj->set_mark(m); 4120 } 4121 _objs_with_preserved_marks.clear(true); 4122 _preserved_marks_of_objs.clear(true); 4123 4124 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0); 4125 } 4126 4127 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) { 4128 _evac_failure_scan_stack->push(obj); 4129 } 4130 4131 void G1CollectedHeap::drain_evac_failure_scan_stack() { 4132 assert(_evac_failure_scan_stack != NULL, "precondition"); 4133 4134 while (_evac_failure_scan_stack->length() > 0) { 4135 oop obj = _evac_failure_scan_stack->pop(); 4136 _evac_failure_closure->set_region(heap_region_containing(obj)); 4137 obj->oop_iterate_backwards(_evac_failure_closure); 4138 } 4139 } 4140 4141 oop 4142 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state, 4143 oop old) { 4144 assert(obj_in_cs(old), 4145 err_msg("obj: "PTR_FORMAT" should still be in the CSet", 4146 (HeapWord*) old)); 4147 markOop m = old->mark(); 4148 oop forward_ptr = old->forward_to_atomic(old); 4149 if (forward_ptr == NULL) { 4150 // Forward-to-self succeeded. 4151 assert(_par_scan_state != NULL, "par scan state"); 4152 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure(); 4153 uint queue_num = _par_scan_state->queue_num(); 4154 4155 _evacuation_failed = true; 4156 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size()); 4157 if (_evac_failure_closure != cl) { 4158 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag); 4159 assert(!_drain_in_progress, 4160 "Should only be true while someone holds the lock."); 4161 // Set the global evac-failure closure to the current thread's. 4162 assert(_evac_failure_closure == NULL, "Or locking has failed."); 4163 set_evac_failure_closure(cl); 4164 // Now do the common part. 4165 handle_evacuation_failure_common(old, m); 4166 // Reset to NULL. 4167 set_evac_failure_closure(NULL); 4168 } else { 4169 // The lock is already held, and this is recursive. 4170 assert(_drain_in_progress, "This should only be the recursive case."); 4171 handle_evacuation_failure_common(old, m); 4172 } 4173 return old; 4174 } else { 4175 // Forward-to-self failed. Either someone else managed to allocate 4176 // space for this object (old != forward_ptr) or they beat us in 4177 // self-forwarding it (old == forward_ptr). 4178 assert(old == forward_ptr || !obj_in_cs(forward_ptr), 4179 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" " 4180 "should not be in the CSet", 4181 (HeapWord*) old, (HeapWord*) forward_ptr)); 4182 return forward_ptr; 4183 } 4184 } 4185 4186 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) { 4187 preserve_mark_if_necessary(old, m); 4188 4189 HeapRegion* r = heap_region_containing(old); 4190 if (!r->evacuation_failed()) { 4191 r->set_evacuation_failed(true); 4192 _hr_printer.evac_failure(r); 4193 } 4194 4195 push_on_evac_failure_scan_stack(old); 4196 4197 if (!_drain_in_progress) { 4198 // prevent recursion in copy_to_survivor_space() 4199 _drain_in_progress = true; 4200 drain_evac_failure_scan_stack(); 4201 _drain_in_progress = false; 4202 } 4203 } 4204 4205 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) { 4206 assert(evacuation_failed(), "Oversaving!"); 4207 // We want to call the "for_promotion_failure" version only in the 4208 // case of a promotion failure. 4209 if (m->must_be_preserved_for_promotion_failure(obj)) { 4210 _objs_with_preserved_marks.push(obj); 4211 _preserved_marks_of_objs.push(m); 4212 } 4213 } 4214 4215 void G1ParCopyHelper::mark_object(oop obj) { 4216 assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet"); 4217 4218 // We know that the object is not moving so it's safe to read its size. 4219 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id); 4220 } 4221 4222 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) { 4223 assert(from_obj->is_forwarded(), "from obj should be forwarded"); 4224 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee"); 4225 assert(from_obj != to_obj, "should not be self-forwarded"); 4226 4227 assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet"); 4228 assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet"); 4229 4230 // The object might be in the process of being copied by another 4231 // worker so we cannot trust that its to-space image is 4232 // well-formed. So we have to read its size from its from-space 4233 // image which we know should not be changing. 4234 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id); 4235 } 4236 4237 template <class T> 4238 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) { 4239 if (_g1->heap_region_containing_raw(new_obj)->is_young()) { 4240 _scanned_klass->record_modified_oops(); 4241 } 4242 } 4243 4244 template <G1Barrier barrier, G1Mark do_mark_object> 4245 template <class T> 4246 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) { 4247 T heap_oop = oopDesc::load_heap_oop(p); 4248 4249 if (oopDesc::is_null(heap_oop)) { 4250 return; 4251 } 4252 4253 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 4254 4255 assert(_worker_id == _par_scan_state->queue_num(), "sanity"); 4256 4257 const InCSetState state = _g1->in_cset_state(obj); 4258 if (state.is_in_cset()) { 4259 oop forwardee; 4260 markOop m = obj->mark(); 4261 if (m->is_marked()) { 4262 forwardee = (oop) m->decode_pointer(); 4263 } else { 4264 forwardee = _par_scan_state->copy_to_survivor_space(state, obj, m); 4265 } 4266 assert(forwardee != NULL, "forwardee should not be NULL"); 4267 oopDesc::encode_store_heap_oop(p, forwardee); 4268 if (do_mark_object != G1MarkNone && forwardee != obj) { 4269 // If the object is self-forwarded we don't need to explicitly 4270 // mark it, the evacuation failure protocol will do so. 4271 mark_forwarded_object(obj, forwardee); 4272 } 4273 4274 if (barrier == G1BarrierKlass) { 4275 do_klass_barrier(p, forwardee); 4276 } 4277 } else { 4278 if (state.is_humongous()) { 4279 _g1->set_humongous_is_live(obj); 4280 } 4281 // The object is not in collection set. If we're a root scanning 4282 // closure during an initial mark pause then attempt to mark the object. 4283 if (do_mark_object == G1MarkFromRoot) { 4284 mark_object(obj); 4285 } 4286 } 4287 4288 if (barrier == G1BarrierEvac) { 4289 _par_scan_state->update_rs(_from, p, _worker_id); 4290 } 4291 } 4292 4293 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(oop* p); 4294 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(narrowOop* p); 4295 4296 class G1ParEvacuateFollowersClosure : public VoidClosure { 4297 protected: 4298 G1CollectedHeap* _g1h; 4299 G1ParScanThreadState* _par_scan_state; 4300 RefToScanQueueSet* _queues; 4301 ParallelTaskTerminator* _terminator; 4302 4303 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 4304 RefToScanQueueSet* queues() { return _queues; } 4305 ParallelTaskTerminator* terminator() { return _terminator; } 4306 4307 public: 4308 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h, 4309 G1ParScanThreadState* par_scan_state, 4310 RefToScanQueueSet* queues, 4311 ParallelTaskTerminator* terminator) 4312 : _g1h(g1h), _par_scan_state(par_scan_state), 4313 _queues(queues), _terminator(terminator) {} 4314 4315 void do_void(); 4316 4317 private: 4318 inline bool offer_termination(); 4319 }; 4320 4321 bool G1ParEvacuateFollowersClosure::offer_termination() { 4322 G1ParScanThreadState* const pss = par_scan_state(); 4323 pss->start_term_time(); 4324 const bool res = terminator()->offer_termination(); 4325 pss->end_term_time(); 4326 return res; 4327 } 4328 4329 void G1ParEvacuateFollowersClosure::do_void() { 4330 G1ParScanThreadState* const pss = par_scan_state(); 4331 pss->trim_queue(); 4332 do { 4333 pss->steal_and_trim_queue(queues()); 4334 } while (!offer_termination()); 4335 } 4336 4337 class G1KlassScanClosure : public KlassClosure { 4338 G1ParCopyHelper* _closure; 4339 bool _process_only_dirty; 4340 int _count; 4341 public: 4342 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty) 4343 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {} 4344 void do_klass(Klass* klass) { 4345 // If the klass has not been dirtied we know that there's 4346 // no references into the young gen and we can skip it. 4347 if (!_process_only_dirty || klass->has_modified_oops()) { 4348 // Clean the klass since we're going to scavenge all the metadata. 4349 klass->clear_modified_oops(); 4350 4351 // Tell the closure that this klass is the Klass to scavenge 4352 // and is the one to dirty if oops are left pointing into the young gen. 4353 _closure->set_scanned_klass(klass); 4354 4355 klass->oops_do(_closure); 4356 4357 _closure->set_scanned_klass(NULL); 4358 } 4359 _count++; 4360 } 4361 }; 4362 4363 class G1CodeBlobClosure : public CodeBlobClosure { 4364 class HeapRegionGatheringOopClosure : public OopClosure { 4365 G1CollectedHeap* _g1h; 4366 OopClosure* _work; 4367 nmethod* _nm; 4368 4369 template <typename T> 4370 void do_oop_work(T* p) { 4371 _work->do_oop(p); 4372 T oop_or_narrowoop = oopDesc::load_heap_oop(p); 4373 if (!oopDesc::is_null(oop_or_narrowoop)) { 4374 oop o = oopDesc::decode_heap_oop_not_null(oop_or_narrowoop); 4375 HeapRegion* hr = _g1h->heap_region_containing_raw(o); 4376 assert(!_g1h->obj_in_cs(o) || hr->rem_set()->strong_code_roots_list_contains(_nm), "if o still in CS then evacuation failed and nm must already be in the remset"); 4377 hr->add_strong_code_root(_nm); 4378 } 4379 } 4380 4381 public: 4382 HeapRegionGatheringOopClosure(OopClosure* oc) : _g1h(G1CollectedHeap::heap()), _work(oc), _nm(NULL) {} 4383 4384 void do_oop(oop* o) { 4385 do_oop_work(o); 4386 } 4387 4388 void do_oop(narrowOop* o) { 4389 do_oop_work(o); 4390 } 4391 4392 void set_nm(nmethod* nm) { 4393 _nm = nm; 4394 } 4395 }; 4396 4397 HeapRegionGatheringOopClosure _oc; 4398 public: 4399 G1CodeBlobClosure(OopClosure* oc) : _oc(oc) {} 4400 4401 void do_code_blob(CodeBlob* cb) { 4402 nmethod* nm = cb->as_nmethod_or_null(); 4403 if (nm != NULL) { 4404 if (!nm->test_set_oops_do_mark()) { 4405 _oc.set_nm(nm); 4406 nm->oops_do(&_oc); 4407 nm->fix_oop_relocations(); 4408 } 4409 } 4410 } 4411 }; 4412 4413 class G1ParTask : public AbstractGangTask { 4414 protected: 4415 G1CollectedHeap* _g1h; 4416 RefToScanQueueSet *_queues; 4417 ParallelTaskTerminator _terminator; 4418 uint _n_workers; 4419 4420 Mutex _stats_lock; 4421 Mutex* stats_lock() { return &_stats_lock; } 4422 4423 public: 4424 G1ParTask(G1CollectedHeap* g1h, RefToScanQueueSet *task_queues) 4425 : AbstractGangTask("G1 collection"), 4426 _g1h(g1h), 4427 _queues(task_queues), 4428 _terminator(0, _queues), 4429 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true) 4430 {} 4431 4432 RefToScanQueueSet* queues() { return _queues; } 4433 4434 RefToScanQueue *work_queue(int i) { 4435 return queues()->queue(i); 4436 } 4437 4438 ParallelTaskTerminator* terminator() { return &_terminator; } 4439 4440 virtual void set_for_termination(int active_workers) { 4441 // This task calls set_n_termination() in par_non_clean_card_iterate_work() 4442 // in the young space (_par_seq_tasks) in the G1 heap 4443 // for SequentialSubTasksDone. 4444 // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap 4445 // both of which need setting by set_n_termination(). 4446 _g1h->SharedHeap::set_n_termination(active_workers); 4447 _g1h->set_n_termination(active_workers); 4448 terminator()->reset_for_reuse(active_workers); 4449 _n_workers = active_workers; 4450 } 4451 4452 // Helps out with CLD processing. 4453 // 4454 // During InitialMark we need to: 4455 // 1) Scavenge all CLDs for the young GC. 4456 // 2) Mark all objects directly reachable from strong CLDs. 4457 template <G1Mark do_mark_object> 4458 class G1CLDClosure : public CLDClosure { 4459 G1ParCopyClosure<G1BarrierNone, do_mark_object>* _oop_closure; 4460 G1ParCopyClosure<G1BarrierKlass, do_mark_object> _oop_in_klass_closure; 4461 G1KlassScanClosure _klass_in_cld_closure; 4462 bool _claim; 4463 4464 public: 4465 G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure, 4466 bool only_young, bool claim) 4467 : _oop_closure(oop_closure), 4468 _oop_in_klass_closure(oop_closure->g1(), 4469 oop_closure->pss(), 4470 oop_closure->rp()), 4471 _klass_in_cld_closure(&_oop_in_klass_closure, only_young), 4472 _claim(claim) { 4473 4474 } 4475 4476 void do_cld(ClassLoaderData* cld) { 4477 cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim); 4478 } 4479 }; 4480 4481 void work(uint worker_id) { 4482 if (worker_id >= _n_workers) return; // no work needed this round 4483 4484 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, os::elapsedTime()); 4485 4486 { 4487 ResourceMark rm; 4488 HandleMark hm; 4489 4490 ReferenceProcessor* rp = _g1h->ref_processor_stw(); 4491 4492 G1ParScanThreadState pss(_g1h, worker_id, rp); 4493 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp); 4494 4495 pss.set_evac_failure_closure(&evac_failure_cl); 4496 4497 bool only_young = _g1h->g1_policy()->gcs_are_young(); 4498 4499 // Non-IM young GC. 4500 G1ParCopyClosure<G1BarrierNone, G1MarkNone> scan_only_root_cl(_g1h, &pss, rp); 4501 G1CLDClosure<G1MarkNone> scan_only_cld_cl(&scan_only_root_cl, 4502 only_young, // Only process dirty klasses. 4503 false); // No need to claim CLDs. 4504 // IM young GC. 4505 // Strong roots closures. 4506 G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot> scan_mark_root_cl(_g1h, &pss, rp); 4507 G1CLDClosure<G1MarkFromRoot> scan_mark_cld_cl(&scan_mark_root_cl, 4508 false, // Process all klasses. 4509 true); // Need to claim CLDs. 4510 // Weak roots closures. 4511 G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, &pss, rp); 4512 G1CLDClosure<G1MarkPromotedFromRoot> scan_mark_weak_cld_cl(&scan_mark_weak_root_cl, 4513 false, // Process all klasses. 4514 true); // Need to claim CLDs. 4515 4516 G1CodeBlobClosure scan_only_code_cl(&scan_only_root_cl); 4517 G1CodeBlobClosure scan_mark_code_cl(&scan_mark_root_cl); 4518 // IM Weak code roots are handled later. 4519 4520 OopClosure* strong_root_cl; 4521 OopClosure* weak_root_cl; 4522 CLDClosure* strong_cld_cl; 4523 CLDClosure* weak_cld_cl; 4524 CodeBlobClosure* strong_code_cl; 4525 4526 if (_g1h->g1_policy()->during_initial_mark_pause()) { 4527 // We also need to mark copied objects. 4528 strong_root_cl = &scan_mark_root_cl; 4529 strong_cld_cl = &scan_mark_cld_cl; 4530 strong_code_cl = &scan_mark_code_cl; 4531 if (ClassUnloadingWithConcurrentMark) { 4532 weak_root_cl = &scan_mark_weak_root_cl; 4533 weak_cld_cl = &scan_mark_weak_cld_cl; 4534 } else { 4535 weak_root_cl = &scan_mark_root_cl; 4536 weak_cld_cl = &scan_mark_cld_cl; 4537 } 4538 } else { 4539 strong_root_cl = &scan_only_root_cl; 4540 weak_root_cl = &scan_only_root_cl; 4541 strong_cld_cl = &scan_only_cld_cl; 4542 weak_cld_cl = &scan_only_cld_cl; 4543 strong_code_cl = &scan_only_code_cl; 4544 } 4545 4546 4547 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss); 4548 4549 pss.start_strong_roots(); 4550 _g1h->g1_process_roots(strong_root_cl, 4551 weak_root_cl, 4552 &push_heap_rs_cl, 4553 strong_cld_cl, 4554 weak_cld_cl, 4555 strong_code_cl, 4556 worker_id); 4557 4558 pss.end_strong_roots(); 4559 4560 { 4561 double start = os::elapsedTime(); 4562 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator); 4563 evac.do_void(); 4564 double elapsed_sec = os::elapsedTime() - start; 4565 double term_sec = pss.term_time(); 4566 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec); 4567 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec); 4568 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, pss.term_attempts()); 4569 } 4570 _g1h->g1_policy()->record_thread_age_table(pss.age_table()); 4571 _g1h->update_surviving_young_words(pss.surviving_young_words()+1); 4572 4573 if (PrintTerminationStats) { 4574 MutexLocker x(stats_lock()); 4575 pss.print_termination_stats(worker_id); 4576 } 4577 4578 assert(pss.queue_is_empty(), "should be empty"); 4579 4580 // Close the inner scope so that the ResourceMark and HandleMark 4581 // destructors are executed here and are included as part of the 4582 // "GC Worker Time". 4583 } 4584 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime()); 4585 } 4586 }; 4587 4588 // *** Common G1 Evacuation Stuff 4589 4590 // This method is run in a GC worker. 4591 4592 void 4593 G1CollectedHeap:: 4594 g1_process_roots(OopClosure* scan_non_heap_roots, 4595 OopClosure* scan_non_heap_weak_roots, 4596 G1ParPushHeapRSClosure* scan_rs, 4597 CLDClosure* scan_strong_clds, 4598 CLDClosure* scan_weak_clds, 4599 CodeBlobClosure* scan_strong_code, 4600 uint worker_i) { 4601 4602 // First scan the shared roots. 4603 double ext_roots_start = os::elapsedTime(); 4604 double closure_app_time_sec = 0.0; 4605 4606 bool during_im = _g1h->g1_policy()->during_initial_mark_pause(); 4607 bool trace_metadata = during_im && ClassUnloadingWithConcurrentMark; 4608 4609 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots); 4610 BufferingOopClosure buf_scan_non_heap_weak_roots(scan_non_heap_weak_roots); 4611 4612 process_roots(false, // no scoping; this is parallel code 4613 SharedHeap::SO_None, 4614 &buf_scan_non_heap_roots, 4615 &buf_scan_non_heap_weak_roots, 4616 scan_strong_clds, 4617 // Unloading Initial Marks handle the weak CLDs separately. 4618 (trace_metadata ? NULL : scan_weak_clds), 4619 scan_strong_code); 4620 4621 // Now the CM ref_processor roots. 4622 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) { 4623 // We need to treat the discovered reference lists of the 4624 // concurrent mark ref processor as roots and keep entries 4625 // (which are added by the marking threads) on them live 4626 // until they can be processed at the end of marking. 4627 ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots); 4628 } 4629 4630 if (trace_metadata) { 4631 // Barrier to make sure all workers passed 4632 // the strong CLD and strong nmethods phases. 4633 active_strong_roots_scope()->wait_until_all_workers_done_with_threads(n_par_threads()); 4634 4635 // Now take the complement of the strong CLDs. 4636 ClassLoaderDataGraph::roots_cld_do(NULL, scan_weak_clds); 4637 } 4638 4639 // Finish up any enqueued closure apps (attributed as object copy time). 4640 buf_scan_non_heap_roots.done(); 4641 buf_scan_non_heap_weak_roots.done(); 4642 4643 double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds() 4644 + buf_scan_non_heap_weak_roots.closure_app_seconds(); 4645 4646 g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::ObjCopy, worker_i, obj_copy_time_sec); 4647 4648 double ext_root_time_sec = os::elapsedTime() - ext_roots_start - obj_copy_time_sec; 4649 g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::ExtRootScan, worker_i, ext_root_time_sec); 4650 4651 // During conc marking we have to filter the per-thread SATB buffers 4652 // to make sure we remove any oops into the CSet (which will show up 4653 // as implicitly live). 4654 { 4655 G1GCParPhaseTimesTracker x(g1_policy()->phase_times(), G1GCPhaseTimes::SATBFiltering, worker_i); 4656 if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers) && mark_in_progress()) { 4657 JavaThread::satb_mark_queue_set().filter_thread_buffers(); 4658 } 4659 } 4660 4661 // Now scan the complement of the collection set. 4662 G1CodeBlobClosure scavenge_cs_nmethods(scan_non_heap_weak_roots); 4663 4664 g1_rem_set()->oops_into_collection_set_do(scan_rs, &scavenge_cs_nmethods, worker_i); 4665 4666 _process_strong_tasks->all_tasks_completed(); 4667 } 4668 4669 class G1StringSymbolTableUnlinkTask : public AbstractGangTask { 4670 private: 4671 BoolObjectClosure* _is_alive; 4672 int _initial_string_table_size; 4673 int _initial_symbol_table_size; 4674 4675 bool _process_strings; 4676 int _strings_processed; 4677 int _strings_removed; 4678 4679 bool _process_symbols; 4680 int _symbols_processed; 4681 int _symbols_removed; 4682 4683 public: 4684 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) : 4685 AbstractGangTask("String/Symbol Unlinking"), 4686 _is_alive(is_alive), 4687 _process_strings(process_strings), _strings_processed(0), _strings_removed(0), 4688 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) { 4689 4690 _initial_string_table_size = StringTable::the_table()->table_size(); 4691 _initial_symbol_table_size = SymbolTable::the_table()->table_size(); 4692 if (process_strings) { 4693 StringTable::clear_parallel_claimed_index(); 4694 } 4695 if (process_symbols) { 4696 SymbolTable::clear_parallel_claimed_index(); 4697 } 4698 } 4699 4700 ~G1StringSymbolTableUnlinkTask() { 4701 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size, 4702 err_msg("claim value %d after unlink less than initial string table size %d", 4703 StringTable::parallel_claimed_index(), _initial_string_table_size)); 4704 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size, 4705 err_msg("claim value %d after unlink less than initial symbol table size %d", 4706 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size)); 4707 4708 if (G1TraceStringSymbolTableScrubbing) { 4709 gclog_or_tty->print_cr("Cleaned string and symbol table, " 4710 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, " 4711 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed", 4712 strings_processed(), strings_removed(), 4713 symbols_processed(), symbols_removed()); 4714 } 4715 } 4716 4717 void work(uint worker_id) { 4718 int strings_processed = 0; 4719 int strings_removed = 0; 4720 int symbols_processed = 0; 4721 int symbols_removed = 0; 4722 if (_process_strings) { 4723 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed); 4724 Atomic::add(strings_processed, &_strings_processed); 4725 Atomic::add(strings_removed, &_strings_removed); 4726 } 4727 if (_process_symbols) { 4728 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed); 4729 Atomic::add(symbols_processed, &_symbols_processed); 4730 Atomic::add(symbols_removed, &_symbols_removed); 4731 } 4732 } 4733 4734 size_t strings_processed() const { return (size_t)_strings_processed; } 4735 size_t strings_removed() const { return (size_t)_strings_removed; } 4736 4737 size_t symbols_processed() const { return (size_t)_symbols_processed; } 4738 size_t symbols_removed() const { return (size_t)_symbols_removed; } 4739 }; 4740 4741 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC { 4742 private: 4743 static Monitor* _lock; 4744 4745 BoolObjectClosure* const _is_alive; 4746 const bool _unloading_occurred; 4747 const uint _num_workers; 4748 4749 // Variables used to claim nmethods. 4750 nmethod* _first_nmethod; 4751 volatile nmethod* _claimed_nmethod; 4752 4753 // The list of nmethods that need to be processed by the second pass. 4754 volatile nmethod* _postponed_list; 4755 volatile uint _num_entered_barrier; 4756 4757 public: 4758 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) : 4759 _is_alive(is_alive), 4760 _unloading_occurred(unloading_occurred), 4761 _num_workers(num_workers), 4762 _first_nmethod(NULL), 4763 _claimed_nmethod(NULL), 4764 _postponed_list(NULL), 4765 _num_entered_barrier(0) 4766 { 4767 nmethod::increase_unloading_clock(); 4768 // Get first alive nmethod 4769 NMethodIterator iter = NMethodIterator(); 4770 if(iter.next_alive()) { 4771 _first_nmethod = iter.method(); 4772 } 4773 _claimed_nmethod = (volatile nmethod*)_first_nmethod; 4774 } 4775 4776 ~G1CodeCacheUnloadingTask() { 4777 CodeCache::verify_clean_inline_caches(); 4778 4779 CodeCache::set_needs_cache_clean(false); 4780 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be"); 4781 4782 CodeCache::verify_icholder_relocations(); 4783 } 4784 4785 private: 4786 void add_to_postponed_list(nmethod* nm) { 4787 nmethod* old; 4788 do { 4789 old = (nmethod*)_postponed_list; 4790 nm->set_unloading_next(old); 4791 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old); 4792 } 4793 4794 void clean_nmethod(nmethod* nm) { 4795 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred); 4796 4797 if (postponed) { 4798 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet. 4799 add_to_postponed_list(nm); 4800 } 4801 4802 // Mark that this thread has been cleaned/unloaded. 4803 // After this call, it will be safe to ask if this nmethod was unloaded or not. 4804 nm->set_unloading_clock(nmethod::global_unloading_clock()); 4805 } 4806 4807 void clean_nmethod_postponed(nmethod* nm) { 4808 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred); 4809 } 4810 4811 static const int MaxClaimNmethods = 16; 4812 4813 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) { 4814 nmethod* first; 4815 NMethodIterator last; 4816 4817 do { 4818 *num_claimed_nmethods = 0; 4819 4820 first = (nmethod*)_claimed_nmethod; 4821 last = NMethodIterator(first); 4822 4823 if (first != NULL) { 4824 4825 for (int i = 0; i < MaxClaimNmethods; i++) { 4826 if (!last.next_alive()) { 4827 break; 4828 } 4829 claimed_nmethods[i] = last.method(); 4830 (*num_claimed_nmethods)++; 4831 } 4832 } 4833 4834 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first); 4835 } 4836 4837 nmethod* claim_postponed_nmethod() { 4838 nmethod* claim; 4839 nmethod* next; 4840 4841 do { 4842 claim = (nmethod*)_postponed_list; 4843 if (claim == NULL) { 4844 return NULL; 4845 } 4846 4847 next = claim->unloading_next(); 4848 4849 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim); 4850 4851 return claim; 4852 } 4853 4854 public: 4855 // Mark that we're done with the first pass of nmethod cleaning. 4856 void barrier_mark(uint worker_id) { 4857 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 4858 _num_entered_barrier++; 4859 if (_num_entered_barrier == _num_workers) { 4860 ml.notify_all(); 4861 } 4862 } 4863 4864 // See if we have to wait for the other workers to 4865 // finish their first-pass nmethod cleaning work. 4866 void barrier_wait(uint worker_id) { 4867 if (_num_entered_barrier < _num_workers) { 4868 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 4869 while (_num_entered_barrier < _num_workers) { 4870 ml.wait(Mutex::_no_safepoint_check_flag, 0, false); 4871 } 4872 } 4873 } 4874 4875 // Cleaning and unloading of nmethods. Some work has to be postponed 4876 // to the second pass, when we know which nmethods survive. 4877 void work_first_pass(uint worker_id) { 4878 // The first nmethods is claimed by the first worker. 4879 if (worker_id == 0 && _first_nmethod != NULL) { 4880 clean_nmethod(_first_nmethod); 4881 _first_nmethod = NULL; 4882 } 4883 4884 int num_claimed_nmethods; 4885 nmethod* claimed_nmethods[MaxClaimNmethods]; 4886 4887 while (true) { 4888 claim_nmethods(claimed_nmethods, &num_claimed_nmethods); 4889 4890 if (num_claimed_nmethods == 0) { 4891 break; 4892 } 4893 4894 for (int i = 0; i < num_claimed_nmethods; i++) { 4895 clean_nmethod(claimed_nmethods[i]); 4896 } 4897 } 4898 4899 // The nmethod cleaning helps out and does the CodeCache part of MetadataOnStackMark. 4900 // Need to retire the buffers now that this thread has stopped cleaning nmethods. 4901 MetadataOnStackMark::retire_buffer_for_thread(Thread::current()); 4902 } 4903 4904 void work_second_pass(uint worker_id) { 4905 nmethod* nm; 4906 // Take care of postponed nmethods. 4907 while ((nm = claim_postponed_nmethod()) != NULL) { 4908 clean_nmethod_postponed(nm); 4909 } 4910 } 4911 }; 4912 4913 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never); 4914 4915 class G1KlassCleaningTask : public StackObj { 4916 BoolObjectClosure* _is_alive; 4917 volatile jint _clean_klass_tree_claimed; 4918 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator; 4919 4920 public: 4921 G1KlassCleaningTask(BoolObjectClosure* is_alive) : 4922 _is_alive(is_alive), 4923 _clean_klass_tree_claimed(0), 4924 _klass_iterator() { 4925 } 4926 4927 private: 4928 bool claim_clean_klass_tree_task() { 4929 if (_clean_klass_tree_claimed) { 4930 return false; 4931 } 4932 4933 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0; 4934 } 4935 4936 InstanceKlass* claim_next_klass() { 4937 Klass* klass; 4938 do { 4939 klass =_klass_iterator.next_klass(); 4940 } while (klass != NULL && !klass->oop_is_instance()); 4941 4942 return (InstanceKlass*)klass; 4943 } 4944 4945 public: 4946 4947 void clean_klass(InstanceKlass* ik) { 4948 ik->clean_implementors_list(_is_alive); 4949 ik->clean_method_data(_is_alive); 4950 4951 // G1 specific cleanup work that has 4952 // been moved here to be done in parallel. 4953 ik->clean_dependent_nmethods(); 4954 if (JvmtiExport::has_redefined_a_class()) { 4955 InstanceKlass::purge_previous_versions(ik); 4956 } 4957 } 4958 4959 void work() { 4960 ResourceMark rm; 4961 4962 // One worker will clean the subklass/sibling klass tree. 4963 if (claim_clean_klass_tree_task()) { 4964 Klass::clean_subklass_tree(_is_alive); 4965 } 4966 4967 // All workers will help cleaning the classes, 4968 InstanceKlass* klass; 4969 while ((klass = claim_next_klass()) != NULL) { 4970 clean_klass(klass); 4971 } 4972 } 4973 }; 4974 4975 // To minimize the remark pause times, the tasks below are done in parallel. 4976 class G1ParallelCleaningTask : public AbstractGangTask { 4977 private: 4978 G1StringSymbolTableUnlinkTask _string_symbol_task; 4979 G1CodeCacheUnloadingTask _code_cache_task; 4980 G1KlassCleaningTask _klass_cleaning_task; 4981 4982 public: 4983 // The constructor is run in the VMThread. 4984 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) : 4985 AbstractGangTask("Parallel Cleaning"), 4986 _string_symbol_task(is_alive, process_strings, process_symbols), 4987 _code_cache_task(num_workers, is_alive, unloading_occurred), 4988 _klass_cleaning_task(is_alive) { 4989 } 4990 4991 void pre_work_verification() { 4992 assert(!MetadataOnStackMark::has_buffer_for_thread(Thread::current()), "Should be empty"); 4993 } 4994 4995 void post_work_verification() { 4996 assert(!MetadataOnStackMark::has_buffer_for_thread(Thread::current()), "Should be empty"); 4997 } 4998 4999 // The parallel work done by all worker threads. 5000 void work(uint worker_id) { 5001 pre_work_verification(); 5002 5003 // Do first pass of code cache cleaning. 5004 _code_cache_task.work_first_pass(worker_id); 5005 5006 // Let the threads mark that the first pass is done. 5007 _code_cache_task.barrier_mark(worker_id); 5008 5009 // Clean the Strings and Symbols. 5010 _string_symbol_task.work(worker_id); 5011 5012 // Wait for all workers to finish the first code cache cleaning pass. 5013 _code_cache_task.barrier_wait(worker_id); 5014 5015 // Do the second code cache cleaning work, which realize on 5016 // the liveness information gathered during the first pass. 5017 _code_cache_task.work_second_pass(worker_id); 5018 5019 // Clean all klasses that were not unloaded. 5020 _klass_cleaning_task.work(); 5021 5022 post_work_verification(); 5023 } 5024 }; 5025 5026 5027 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive, 5028 bool process_strings, 5029 bool process_symbols, 5030 bool class_unloading_occurred) { 5031 uint n_workers = workers()->active_workers(); 5032 5033 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, 5034 n_workers, class_unloading_occurred); 5035 set_par_threads(n_workers); 5036 workers()->run_task(&g1_unlink_task); 5037 set_par_threads(0); 5038 } 5039 5040 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive, 5041 bool process_strings, bool process_symbols) { 5042 { 5043 uint n_workers = _g1h->workers()->active_workers(); 5044 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols); 5045 set_par_threads(n_workers); 5046 workers()->run_task(&g1_unlink_task); 5047 set_par_threads(0); 5048 } 5049 5050 if (G1StringDedup::is_enabled()) { 5051 G1StringDedup::unlink(is_alive); 5052 } 5053 } 5054 5055 class G1RedirtyLoggedCardsTask : public AbstractGangTask { 5056 private: 5057 DirtyCardQueueSet* _queue; 5058 public: 5059 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { } 5060 5061 virtual void work(uint worker_id) { 5062 G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times(); 5063 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id); 5064 5065 RedirtyLoggedCardTableEntryClosure cl; 5066 _queue->par_apply_closure_to_all_completed_buffers(&cl); 5067 5068 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed()); 5069 } 5070 }; 5071 5072 void G1CollectedHeap::redirty_logged_cards() { 5073 double redirty_logged_cards_start = os::elapsedTime(); 5074 5075 uint n_workers = _g1h->workers()->active_workers(); 5076 5077 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set()); 5078 dirty_card_queue_set().reset_for_par_iteration(); 5079 set_par_threads(n_workers); 5080 workers()->run_task(&redirty_task); 5081 set_par_threads(0); 5082 5083 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set(); 5084 dcq.merge_bufferlists(&dirty_card_queue_set()); 5085 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed"); 5086 5087 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0); 5088 } 5089 5090 // Weak Reference Processing support 5091 5092 // An always "is_alive" closure that is used to preserve referents. 5093 // If the object is non-null then it's alive. Used in the preservation 5094 // of referent objects that are pointed to by reference objects 5095 // discovered by the CM ref processor. 5096 class G1AlwaysAliveClosure: public BoolObjectClosure { 5097 G1CollectedHeap* _g1; 5098 public: 5099 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 5100 bool do_object_b(oop p) { 5101 if (p != NULL) { 5102 return true; 5103 } 5104 return false; 5105 } 5106 }; 5107 5108 bool G1STWIsAliveClosure::do_object_b(oop p) { 5109 // An object is reachable if it is outside the collection set, 5110 // or is inside and copied. 5111 return !_g1->obj_in_cs(p) || p->is_forwarded(); 5112 } 5113 5114 // Non Copying Keep Alive closure 5115 class G1KeepAliveClosure: public OopClosure { 5116 G1CollectedHeap* _g1; 5117 public: 5118 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 5119 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } 5120 void do_oop(oop* p) { 5121 oop obj = *p; 5122 assert(obj != NULL, "the caller should have filtered out NULL values"); 5123 5124 const InCSetState cset_state = _g1->in_cset_state(obj); 5125 if (!cset_state.is_in_cset_or_humongous()) { 5126 return; 5127 } 5128 if (cset_state.is_in_cset()) { 5129 assert( obj->is_forwarded(), "invariant" ); 5130 *p = obj->forwardee(); 5131 } else { 5132 assert(!obj->is_forwarded(), "invariant" ); 5133 assert(cset_state.is_humongous(), 5134 err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state.value())); 5135 _g1->set_humongous_is_live(obj); 5136 } 5137 } 5138 }; 5139 5140 // Copying Keep Alive closure - can be called from both 5141 // serial and parallel code as long as different worker 5142 // threads utilize different G1ParScanThreadState instances 5143 // and different queues. 5144 5145 class G1CopyingKeepAliveClosure: public OopClosure { 5146 G1CollectedHeap* _g1h; 5147 OopClosure* _copy_non_heap_obj_cl; 5148 G1ParScanThreadState* _par_scan_state; 5149 5150 public: 5151 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, 5152 OopClosure* non_heap_obj_cl, 5153 G1ParScanThreadState* pss): 5154 _g1h(g1h), 5155 _copy_non_heap_obj_cl(non_heap_obj_cl), 5156 _par_scan_state(pss) 5157 {} 5158 5159 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 5160 virtual void do_oop( oop* p) { do_oop_work(p); } 5161 5162 template <class T> void do_oop_work(T* p) { 5163 oop obj = oopDesc::load_decode_heap_oop(p); 5164 5165 if (_g1h->is_in_cset_or_humongous(obj)) { 5166 // If the referent object has been forwarded (either copied 5167 // to a new location or to itself in the event of an 5168 // evacuation failure) then we need to update the reference 5169 // field and, if both reference and referent are in the G1 5170 // heap, update the RSet for the referent. 5171 // 5172 // If the referent has not been forwarded then we have to keep 5173 // it alive by policy. Therefore we have copy the referent. 5174 // 5175 // If the reference field is in the G1 heap then we can push 5176 // on the PSS queue. When the queue is drained (after each 5177 // phase of reference processing) the object and it's followers 5178 // will be copied, the reference field set to point to the 5179 // new location, and the RSet updated. Otherwise we need to 5180 // use the the non-heap or metadata closures directly to copy 5181 // the referent object and update the pointer, while avoiding 5182 // updating the RSet. 5183 5184 if (_g1h->is_in_g1_reserved(p)) { 5185 _par_scan_state->push_on_queue(p); 5186 } else { 5187 assert(!Metaspace::contains((const void*)p), 5188 err_msg("Unexpectedly found a pointer from metadata: " 5189 PTR_FORMAT, p)); 5190 _copy_non_heap_obj_cl->do_oop(p); 5191 } 5192 } 5193 } 5194 }; 5195 5196 // Serial drain queue closure. Called as the 'complete_gc' 5197 // closure for each discovered list in some of the 5198 // reference processing phases. 5199 5200 class G1STWDrainQueueClosure: public VoidClosure { 5201 protected: 5202 G1CollectedHeap* _g1h; 5203 G1ParScanThreadState* _par_scan_state; 5204 5205 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 5206 5207 public: 5208 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : 5209 _g1h(g1h), 5210 _par_scan_state(pss) 5211 { } 5212 5213 void do_void() { 5214 G1ParScanThreadState* const pss = par_scan_state(); 5215 pss->trim_queue(); 5216 } 5217 }; 5218 5219 // Parallel Reference Processing closures 5220 5221 // Implementation of AbstractRefProcTaskExecutor for parallel reference 5222 // processing during G1 evacuation pauses. 5223 5224 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 5225 private: 5226 G1CollectedHeap* _g1h; 5227 RefToScanQueueSet* _queues; 5228 FlexibleWorkGang* _workers; 5229 int _active_workers; 5230 5231 public: 5232 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, 5233 FlexibleWorkGang* workers, 5234 RefToScanQueueSet *task_queues, 5235 int n_workers) : 5236 _g1h(g1h), 5237 _queues(task_queues), 5238 _workers(workers), 5239 _active_workers(n_workers) 5240 { 5241 assert(n_workers > 0, "shouldn't call this otherwise"); 5242 } 5243 5244 // Executes the given task using concurrent marking worker threads. 5245 virtual void execute(ProcessTask& task); 5246 virtual void execute(EnqueueTask& task); 5247 }; 5248 5249 // Gang task for possibly parallel reference processing 5250 5251 class G1STWRefProcTaskProxy: public AbstractGangTask { 5252 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 5253 ProcessTask& _proc_task; 5254 G1CollectedHeap* _g1h; 5255 RefToScanQueueSet *_task_queues; 5256 ParallelTaskTerminator* _terminator; 5257 5258 public: 5259 G1STWRefProcTaskProxy(ProcessTask& proc_task, 5260 G1CollectedHeap* g1h, 5261 RefToScanQueueSet *task_queues, 5262 ParallelTaskTerminator* terminator) : 5263 AbstractGangTask("Process reference objects in parallel"), 5264 _proc_task(proc_task), 5265 _g1h(g1h), 5266 _task_queues(task_queues), 5267 _terminator(terminator) 5268 {} 5269 5270 virtual void work(uint worker_id) { 5271 // The reference processing task executed by a single worker. 5272 ResourceMark rm; 5273 HandleMark hm; 5274 5275 G1STWIsAliveClosure is_alive(_g1h); 5276 5277 G1ParScanThreadState pss(_g1h, worker_id, NULL); 5278 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL); 5279 5280 pss.set_evac_failure_closure(&evac_failure_cl); 5281 5282 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL); 5283 5284 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL); 5285 5286 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5287 5288 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5289 // We also need to mark copied objects. 5290 copy_non_heap_cl = ©_mark_non_heap_cl; 5291 } 5292 5293 // Keep alive closure. 5294 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss); 5295 5296 // Complete GC closure 5297 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator); 5298 5299 // Call the reference processing task's work routine. 5300 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); 5301 5302 // Note we cannot assert that the refs array is empty here as not all 5303 // of the processing tasks (specifically phase2 - pp2_work) execute 5304 // the complete_gc closure (which ordinarily would drain the queue) so 5305 // the queue may not be empty. 5306 } 5307 }; 5308 5309 // Driver routine for parallel reference processing. 5310 // Creates an instance of the ref processing gang 5311 // task and has the worker threads execute it. 5312 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) { 5313 assert(_workers != NULL, "Need parallel worker threads."); 5314 5315 ParallelTaskTerminator terminator(_active_workers, _queues); 5316 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator); 5317 5318 _g1h->set_par_threads(_active_workers); 5319 _workers->run_task(&proc_task_proxy); 5320 _g1h->set_par_threads(0); 5321 } 5322 5323 // Gang task for parallel reference enqueueing. 5324 5325 class G1STWRefEnqueueTaskProxy: public AbstractGangTask { 5326 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; 5327 EnqueueTask& _enq_task; 5328 5329 public: 5330 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) : 5331 AbstractGangTask("Enqueue reference objects in parallel"), 5332 _enq_task(enq_task) 5333 { } 5334 5335 virtual void work(uint worker_id) { 5336 _enq_task.work(worker_id); 5337 } 5338 }; 5339 5340 // Driver routine for parallel reference enqueueing. 5341 // Creates an instance of the ref enqueueing gang 5342 // task and has the worker threads execute it. 5343 5344 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) { 5345 assert(_workers != NULL, "Need parallel worker threads."); 5346 5347 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task); 5348 5349 _g1h->set_par_threads(_active_workers); 5350 _workers->run_task(&enq_task_proxy); 5351 _g1h->set_par_threads(0); 5352 } 5353 5354 // End of weak reference support closures 5355 5356 // Abstract task used to preserve (i.e. copy) any referent objects 5357 // that are in the collection set and are pointed to by reference 5358 // objects discovered by the CM ref processor. 5359 5360 class G1ParPreserveCMReferentsTask: public AbstractGangTask { 5361 protected: 5362 G1CollectedHeap* _g1h; 5363 RefToScanQueueSet *_queues; 5364 ParallelTaskTerminator _terminator; 5365 uint _n_workers; 5366 5367 public: 5368 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) : 5369 AbstractGangTask("ParPreserveCMReferents"), 5370 _g1h(g1h), 5371 _queues(task_queues), 5372 _terminator(workers, _queues), 5373 _n_workers(workers) 5374 { } 5375 5376 void work(uint worker_id) { 5377 ResourceMark rm; 5378 HandleMark hm; 5379 5380 G1ParScanThreadState pss(_g1h, worker_id, NULL); 5381 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL); 5382 5383 pss.set_evac_failure_closure(&evac_failure_cl); 5384 5385 assert(pss.queue_is_empty(), "both queue and overflow should be empty"); 5386 5387 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL); 5388 5389 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL); 5390 5391 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5392 5393 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5394 // We also need to mark copied objects. 5395 copy_non_heap_cl = ©_mark_non_heap_cl; 5396 } 5397 5398 // Is alive closure 5399 G1AlwaysAliveClosure always_alive(_g1h); 5400 5401 // Copying keep alive closure. Applied to referent objects that need 5402 // to be copied. 5403 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss); 5404 5405 ReferenceProcessor* rp = _g1h->ref_processor_cm(); 5406 5407 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q(); 5408 uint stride = MIN2(MAX2(_n_workers, 1U), limit); 5409 5410 // limit is set using max_num_q() - which was set using ParallelGCThreads. 5411 // So this must be true - but assert just in case someone decides to 5412 // change the worker ids. 5413 assert(0 <= worker_id && worker_id < limit, "sanity"); 5414 assert(!rp->discovery_is_atomic(), "check this code"); 5415 5416 // Select discovered lists [i, i+stride, i+2*stride,...,limit) 5417 for (uint idx = worker_id; idx < limit; idx += stride) { 5418 DiscoveredList& ref_list = rp->discovered_refs()[idx]; 5419 5420 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive); 5421 while (iter.has_next()) { 5422 // Since discovery is not atomic for the CM ref processor, we 5423 // can see some null referent objects. 5424 iter.load_ptrs(DEBUG_ONLY(true)); 5425 oop ref = iter.obj(); 5426 5427 // This will filter nulls. 5428 if (iter.is_referent_alive()) { 5429 iter.make_referent_alive(); 5430 } 5431 iter.move_to_next(); 5432 } 5433 } 5434 5435 // Drain the queue - which may cause stealing 5436 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator); 5437 drain_queue.do_void(); 5438 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure 5439 assert(pss.queue_is_empty(), "should be"); 5440 } 5441 }; 5442 5443 // Weak Reference processing during an evacuation pause (part 1). 5444 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) { 5445 double ref_proc_start = os::elapsedTime(); 5446 5447 ReferenceProcessor* rp = _ref_processor_stw; 5448 assert(rp->discovery_enabled(), "should have been enabled"); 5449 5450 // Any reference objects, in the collection set, that were 'discovered' 5451 // by the CM ref processor should have already been copied (either by 5452 // applying the external root copy closure to the discovered lists, or 5453 // by following an RSet entry). 5454 // 5455 // But some of the referents, that are in the collection set, that these 5456 // reference objects point to may not have been copied: the STW ref 5457 // processor would have seen that the reference object had already 5458 // been 'discovered' and would have skipped discovering the reference, 5459 // but would not have treated the reference object as a regular oop. 5460 // As a result the copy closure would not have been applied to the 5461 // referent object. 5462 // 5463 // We need to explicitly copy these referent objects - the references 5464 // will be processed at the end of remarking. 5465 // 5466 // We also need to do this copying before we process the reference 5467 // objects discovered by the STW ref processor in case one of these 5468 // referents points to another object which is also referenced by an 5469 // object discovered by the STW ref processor. 5470 5471 assert(no_of_gc_workers == workers()->active_workers(), "Need to reset active GC workers"); 5472 5473 set_par_threads(no_of_gc_workers); 5474 G1ParPreserveCMReferentsTask keep_cm_referents(this, 5475 no_of_gc_workers, 5476 _task_queues); 5477 5478 workers()->run_task(&keep_cm_referents); 5479 5480 set_par_threads(0); 5481 5482 // Closure to test whether a referent is alive. 5483 G1STWIsAliveClosure is_alive(this); 5484 5485 // Even when parallel reference processing is enabled, the processing 5486 // of JNI refs is serial and performed serially by the current thread 5487 // rather than by a worker. The following PSS will be used for processing 5488 // JNI refs. 5489 5490 // Use only a single queue for this PSS. 5491 G1ParScanThreadState pss(this, 0, NULL); 5492 5493 // We do not embed a reference processor in the copying/scanning 5494 // closures while we're actually processing the discovered 5495 // reference objects. 5496 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL); 5497 5498 pss.set_evac_failure_closure(&evac_failure_cl); 5499 5500 assert(pss.queue_is_empty(), "pre-condition"); 5501 5502 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL); 5503 5504 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL); 5505 5506 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5507 5508 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5509 // We also need to mark copied objects. 5510 copy_non_heap_cl = ©_mark_non_heap_cl; 5511 } 5512 5513 // Keep alive closure. 5514 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, &pss); 5515 5516 // Serial Complete GC closure 5517 G1STWDrainQueueClosure drain_queue(this, &pss); 5518 5519 // Setup the soft refs policy... 5520 rp->setup_policy(false); 5521 5522 ReferenceProcessorStats stats; 5523 if (!rp->processing_is_mt()) { 5524 // Serial reference processing... 5525 stats = rp->process_discovered_references(&is_alive, 5526 &keep_alive, 5527 &drain_queue, 5528 NULL, 5529 _gc_timer_stw, 5530 _gc_tracer_stw->gc_id()); 5531 } else { 5532 // Parallel reference processing 5533 assert(rp->num_q() == no_of_gc_workers, "sanity"); 5534 assert(no_of_gc_workers <= rp->max_num_q(), "sanity"); 5535 5536 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers); 5537 stats = rp->process_discovered_references(&is_alive, 5538 &keep_alive, 5539 &drain_queue, 5540 &par_task_executor, 5541 _gc_timer_stw, 5542 _gc_tracer_stw->gc_id()); 5543 } 5544 5545 _gc_tracer_stw->report_gc_reference_stats(stats); 5546 5547 // We have completed copying any necessary live referent objects. 5548 assert(pss.queue_is_empty(), "both queue and overflow should be empty"); 5549 5550 double ref_proc_time = os::elapsedTime() - ref_proc_start; 5551 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 5552 } 5553 5554 // Weak Reference processing during an evacuation pause (part 2). 5555 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) { 5556 double ref_enq_start = os::elapsedTime(); 5557 5558 ReferenceProcessor* rp = _ref_processor_stw; 5559 assert(!rp->discovery_enabled(), "should have been disabled as part of processing"); 5560 5561 // Now enqueue any remaining on the discovered lists on to 5562 // the pending list. 5563 if (!rp->processing_is_mt()) { 5564 // Serial reference processing... 5565 rp->enqueue_discovered_references(); 5566 } else { 5567 // Parallel reference enqueueing 5568 5569 assert(no_of_gc_workers == workers()->active_workers(), 5570 "Need to reset active workers"); 5571 assert(rp->num_q() == no_of_gc_workers, "sanity"); 5572 assert(no_of_gc_workers <= rp->max_num_q(), "sanity"); 5573 5574 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers); 5575 rp->enqueue_discovered_references(&par_task_executor); 5576 } 5577 5578 rp->verify_no_references_recorded(); 5579 assert(!rp->discovery_enabled(), "should have been disabled"); 5580 5581 // FIXME 5582 // CM's reference processing also cleans up the string and symbol tables. 5583 // Should we do that here also? We could, but it is a serial operation 5584 // and could significantly increase the pause time. 5585 5586 double ref_enq_time = os::elapsedTime() - ref_enq_start; 5587 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0); 5588 } 5589 5590 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) { 5591 _expand_heap_after_alloc_failure = true; 5592 _evacuation_failed = false; 5593 5594 // Should G1EvacuationFailureALot be in effect for this GC? 5595 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) 5596 5597 g1_rem_set()->prepare_for_oops_into_collection_set_do(); 5598 5599 // Disable the hot card cache. 5600 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 5601 hot_card_cache->reset_hot_cache_claimed_index(); 5602 hot_card_cache->set_use_cache(false); 5603 5604 uint n_workers; 5605 n_workers = 5606 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 5607 workers()->active_workers(), 5608 Threads::number_of_non_daemon_threads()); 5609 assert(UseDynamicNumberOfGCThreads || 5610 n_workers == workers()->total_workers(), 5611 "If not dynamic should be using all the workers"); 5612 workers()->set_active_workers(n_workers); 5613 set_par_threads(n_workers); 5614 5615 G1ParTask g1_par_task(this, _task_queues); 5616 5617 init_for_evac_failure(NULL); 5618 5619 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty"); 5620 double start_par_time_sec = os::elapsedTime(); 5621 double end_par_time_sec; 5622 5623 { 5624 StrongRootsScope srs(this); 5625 // InitialMark needs claim bits to keep track of the marked-through CLDs. 5626 if (g1_policy()->during_initial_mark_pause()) { 5627 ClassLoaderDataGraph::clear_claimed_marks(); 5628 } 5629 5630 // The individual threads will set their evac-failure closures. 5631 if (PrintTerminationStats) G1ParScanThreadState::print_termination_stats_hdr(); 5632 // These tasks use ShareHeap::_process_strong_tasks 5633 assert(UseDynamicNumberOfGCThreads || 5634 workers()->active_workers() == workers()->total_workers(), 5635 "If not dynamic should be using all the workers"); 5636 workers()->run_task(&g1_par_task); 5637 end_par_time_sec = os::elapsedTime(); 5638 5639 // Closing the inner scope will execute the destructor 5640 // for the StrongRootsScope object. We record the current 5641 // elapsed time before closing the scope so that time 5642 // taken for the SRS destructor is NOT included in the 5643 // reported parallel time. 5644 } 5645 5646 G1GCPhaseTimes* phase_times = g1_policy()->phase_times(); 5647 5648 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0; 5649 phase_times->record_par_time(par_time_ms); 5650 5651 double code_root_fixup_time_ms = 5652 (os::elapsedTime() - end_par_time_sec) * 1000.0; 5653 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms); 5654 5655 set_par_threads(0); 5656 5657 // Process any discovered reference objects - we have 5658 // to do this _before_ we retire the GC alloc regions 5659 // as we may have to copy some 'reachable' referent 5660 // objects (and their reachable sub-graphs) that were 5661 // not copied during the pause. 5662 process_discovered_references(n_workers); 5663 5664 if (G1StringDedup::is_enabled()) { 5665 double fixup_start = os::elapsedTime(); 5666 5667 G1STWIsAliveClosure is_alive(this); 5668 G1KeepAliveClosure keep_alive(this); 5669 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times); 5670 5671 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0; 5672 phase_times->record_string_dedup_fixup_time(fixup_time_ms); 5673 } 5674 5675 _allocator->release_gc_alloc_regions(n_workers, evacuation_info); 5676 g1_rem_set()->cleanup_after_oops_into_collection_set_do(); 5677 5678 // Reset and re-enable the hot card cache. 5679 // Note the counts for the cards in the regions in the 5680 // collection set are reset when the collection set is freed. 5681 hot_card_cache->reset_hot_cache(); 5682 hot_card_cache->set_use_cache(true); 5683 5684 purge_code_root_memory(); 5685 5686 finalize_for_evac_failure(); 5687 5688 if (evacuation_failed()) { 5689 remove_self_forwarding_pointers(); 5690 5691 // Reset the G1EvacuationFailureALot counters and flags 5692 // Note: the values are reset only when an actual 5693 // evacuation failure occurs. 5694 NOT_PRODUCT(reset_evacuation_should_fail();) 5695 } 5696 5697 // Enqueue any remaining references remaining on the STW 5698 // reference processor's discovered lists. We need to do 5699 // this after the card table is cleaned (and verified) as 5700 // the act of enqueueing entries on to the pending list 5701 // will log these updates (and dirty their associated 5702 // cards). We need these updates logged to update any 5703 // RSets. 5704 enqueue_discovered_references(n_workers); 5705 5706 redirty_logged_cards(); 5707 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 5708 } 5709 5710 void G1CollectedHeap::free_region(HeapRegion* hr, 5711 FreeRegionList* free_list, 5712 bool par, 5713 bool locked) { 5714 assert(!hr->is_free(), "the region should not be free"); 5715 assert(!hr->is_empty(), "the region should not be empty"); 5716 assert(_hrm.is_available(hr->hrm_index()), "region should be committed"); 5717 assert(free_list != NULL, "pre-condition"); 5718 5719 if (G1VerifyBitmaps) { 5720 MemRegion mr(hr->bottom(), hr->end()); 5721 concurrent_mark()->clearRangePrevBitmap(mr); 5722 } 5723 5724 // Clear the card counts for this region. 5725 // Note: we only need to do this if the region is not young 5726 // (since we don't refine cards in young regions). 5727 if (!hr->is_young()) { 5728 _cg1r->hot_card_cache()->reset_card_counts(hr); 5729 } 5730 hr->hr_clear(par, true /* clear_space */, locked /* locked */); 5731 free_list->add_ordered(hr); 5732 } 5733 5734 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 5735 FreeRegionList* free_list, 5736 bool par) { 5737 assert(hr->is_starts_humongous(), "this is only for starts humongous regions"); 5738 assert(free_list != NULL, "pre-condition"); 5739 5740 size_t hr_capacity = hr->capacity(); 5741 // We need to read this before we make the region non-humongous, 5742 // otherwise the information will be gone. 5743 uint last_index = hr->last_hc_index(); 5744 hr->clear_humongous(); 5745 free_region(hr, free_list, par); 5746 5747 uint i = hr->hrm_index() + 1; 5748 while (i < last_index) { 5749 HeapRegion* curr_hr = region_at(i); 5750 assert(curr_hr->is_continues_humongous(), "invariant"); 5751 curr_hr->clear_humongous(); 5752 free_region(curr_hr, free_list, par); 5753 i += 1; 5754 } 5755 } 5756 5757 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed, 5758 const HeapRegionSetCount& humongous_regions_removed) { 5759 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) { 5760 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 5761 _old_set.bulk_remove(old_regions_removed); 5762 _humongous_set.bulk_remove(humongous_regions_removed); 5763 } 5764 5765 } 5766 5767 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) { 5768 assert(list != NULL, "list can't be null"); 5769 if (!list->is_empty()) { 5770 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag); 5771 _hrm.insert_list_into_free_list(list); 5772 } 5773 } 5774 5775 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) { 5776 _allocator->decrease_used(bytes); 5777 } 5778 5779 class G1ParCleanupCTTask : public AbstractGangTask { 5780 G1SATBCardTableModRefBS* _ct_bs; 5781 G1CollectedHeap* _g1h; 5782 HeapRegion* volatile _su_head; 5783 public: 5784 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs, 5785 G1CollectedHeap* g1h) : 5786 AbstractGangTask("G1 Par Cleanup CT Task"), 5787 _ct_bs(ct_bs), _g1h(g1h) { } 5788 5789 void work(uint worker_id) { 5790 HeapRegion* r; 5791 while (r = _g1h->pop_dirty_cards_region()) { 5792 clear_cards(r); 5793 } 5794 } 5795 5796 void clear_cards(HeapRegion* r) { 5797 // Cards of the survivors should have already been dirtied. 5798 if (!r->is_survivor()) { 5799 _ct_bs->clear(MemRegion(r->bottom(), r->end())); 5800 } 5801 } 5802 }; 5803 5804 #ifndef PRODUCT 5805 class G1VerifyCardTableCleanup: public HeapRegionClosure { 5806 G1CollectedHeap* _g1h; 5807 G1SATBCardTableModRefBS* _ct_bs; 5808 public: 5809 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs) 5810 : _g1h(g1h), _ct_bs(ct_bs) { } 5811 virtual bool doHeapRegion(HeapRegion* r) { 5812 if (r->is_survivor()) { 5813 _g1h->verify_dirty_region(r); 5814 } else { 5815 _g1h->verify_not_dirty_region(r); 5816 } 5817 return false; 5818 } 5819 }; 5820 5821 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) { 5822 // All of the region should be clean. 5823 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5824 MemRegion mr(hr->bottom(), hr->end()); 5825 ct_bs->verify_not_dirty_region(mr); 5826 } 5827 5828 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) { 5829 // We cannot guarantee that [bottom(),end()] is dirty. Threads 5830 // dirty allocated blocks as they allocate them. The thread that 5831 // retires each region and replaces it with a new one will do a 5832 // maximal allocation to fill in [pre_dummy_top(),end()] but will 5833 // not dirty that area (one less thing to have to do while holding 5834 // a lock). So we can only verify that [bottom(),pre_dummy_top()] 5835 // is dirty. 5836 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5837 MemRegion mr(hr->bottom(), hr->pre_dummy_top()); 5838 if (hr->is_young()) { 5839 ct_bs->verify_g1_young_region(mr); 5840 } else { 5841 ct_bs->verify_dirty_region(mr); 5842 } 5843 } 5844 5845 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) { 5846 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5847 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) { 5848 verify_dirty_region(hr); 5849 } 5850 } 5851 5852 void G1CollectedHeap::verify_dirty_young_regions() { 5853 verify_dirty_young_list(_young_list->first_region()); 5854 } 5855 5856 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap, 5857 HeapWord* tams, HeapWord* end) { 5858 guarantee(tams <= end, 5859 err_msg("tams: "PTR_FORMAT" end: "PTR_FORMAT, tams, end)); 5860 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end); 5861 if (result < end) { 5862 gclog_or_tty->cr(); 5863 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: "PTR_FORMAT, 5864 bitmap_name, result); 5865 gclog_or_tty->print_cr("## %s tams: "PTR_FORMAT" end: "PTR_FORMAT, 5866 bitmap_name, tams, end); 5867 return false; 5868 } 5869 return true; 5870 } 5871 5872 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) { 5873 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap(); 5874 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap(); 5875 5876 HeapWord* bottom = hr->bottom(); 5877 HeapWord* ptams = hr->prev_top_at_mark_start(); 5878 HeapWord* ntams = hr->next_top_at_mark_start(); 5879 HeapWord* end = hr->end(); 5880 5881 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end); 5882 5883 bool res_n = true; 5884 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window 5885 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap 5886 // if we happen to be in that state. 5887 if (mark_in_progress() || !_cmThread->in_progress()) { 5888 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end); 5889 } 5890 if (!res_p || !res_n) { 5891 gclog_or_tty->print_cr("#### Bitmap verification failed for "HR_FORMAT, 5892 HR_FORMAT_PARAMS(hr)); 5893 gclog_or_tty->print_cr("#### Caller: %s", caller); 5894 return false; 5895 } 5896 return true; 5897 } 5898 5899 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) { 5900 if (!G1VerifyBitmaps) return; 5901 5902 guarantee(verify_bitmaps(caller, hr), "bitmap verification"); 5903 } 5904 5905 class G1VerifyBitmapClosure : public HeapRegionClosure { 5906 private: 5907 const char* _caller; 5908 G1CollectedHeap* _g1h; 5909 bool _failures; 5910 5911 public: 5912 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) : 5913 _caller(caller), _g1h(g1h), _failures(false) { } 5914 5915 bool failures() { return _failures; } 5916 5917 virtual bool doHeapRegion(HeapRegion* hr) { 5918 if (hr->is_continues_humongous()) return false; 5919 5920 bool result = _g1h->verify_bitmaps(_caller, hr); 5921 if (!result) { 5922 _failures = true; 5923 } 5924 return false; 5925 } 5926 }; 5927 5928 void G1CollectedHeap::check_bitmaps(const char* caller) { 5929 if (!G1VerifyBitmaps) return; 5930 5931 G1VerifyBitmapClosure cl(caller, this); 5932 heap_region_iterate(&cl); 5933 guarantee(!cl.failures(), "bitmap verification"); 5934 } 5935 5936 class G1CheckCSetFastTableClosure : public HeapRegionClosure { 5937 private: 5938 bool _failures; 5939 public: 5940 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { } 5941 5942 virtual bool doHeapRegion(HeapRegion* hr) { 5943 uint i = hr->hrm_index(); 5944 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i); 5945 if (hr->is_humongous()) { 5946 if (hr->in_collection_set()) { 5947 gclog_or_tty->print_cr("\n## humongous region %u in CSet", i); 5948 _failures = true; 5949 return true; 5950 } 5951 if (cset_state.is_in_cset()) { 5952 gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i); 5953 _failures = true; 5954 return true; 5955 } 5956 if (hr->is_continues_humongous() && cset_state.is_humongous()) { 5957 gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i); 5958 _failures = true; 5959 return true; 5960 } 5961 } else { 5962 if (cset_state.is_humongous()) { 5963 gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i); 5964 _failures = true; 5965 return true; 5966 } 5967 if (hr->in_collection_set() != cset_state.is_in_cset()) { 5968 gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u", 5969 hr->in_collection_set(), cset_state.value(), i); 5970 _failures = true; 5971 return true; 5972 } 5973 if (cset_state.is_in_cset()) { 5974 if (hr->is_young() != (cset_state.is_young())) { 5975 gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u", 5976 hr->is_young(), cset_state.value(), i); 5977 _failures = true; 5978 return true; 5979 } 5980 if (hr->is_old() != (cset_state.is_old())) { 5981 gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u", 5982 hr->is_old(), cset_state.value(), i); 5983 _failures = true; 5984 return true; 5985 } 5986 } 5987 } 5988 return false; 5989 } 5990 5991 bool failures() const { return _failures; } 5992 }; 5993 5994 bool G1CollectedHeap::check_cset_fast_test() { 5995 G1CheckCSetFastTableClosure cl; 5996 _hrm.iterate(&cl); 5997 return !cl.failures(); 5998 } 5999 #endif // PRODUCT 6000 6001 void G1CollectedHeap::cleanUpCardTable() { 6002 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 6003 double start = os::elapsedTime(); 6004 6005 { 6006 // Iterate over the dirty cards region list. 6007 G1ParCleanupCTTask cleanup_task(ct_bs, this); 6008 6009 set_par_threads(); 6010 workers()->run_task(&cleanup_task); 6011 set_par_threads(0); 6012 #ifndef PRODUCT 6013 if (G1VerifyCTCleanup || VerifyAfterGC) { 6014 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs); 6015 heap_region_iterate(&cleanup_verifier); 6016 } 6017 #endif 6018 } 6019 6020 double elapsed = os::elapsedTime() - start; 6021 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0); 6022 } 6023 6024 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) { 6025 size_t pre_used = 0; 6026 FreeRegionList local_free_list("Local List for CSet Freeing"); 6027 6028 double young_time_ms = 0.0; 6029 double non_young_time_ms = 0.0; 6030 6031 // Since the collection set is a superset of the the young list, 6032 // all we need to do to clear the young list is clear its 6033 // head and length, and unlink any young regions in the code below 6034 _young_list->clear(); 6035 6036 G1CollectorPolicy* policy = g1_policy(); 6037 6038 double start_sec = os::elapsedTime(); 6039 bool non_young = true; 6040 6041 HeapRegion* cur = cs_head; 6042 int age_bound = -1; 6043 size_t rs_lengths = 0; 6044 6045 while (cur != NULL) { 6046 assert(!is_on_master_free_list(cur), "sanity"); 6047 if (non_young) { 6048 if (cur->is_young()) { 6049 double end_sec = os::elapsedTime(); 6050 double elapsed_ms = (end_sec - start_sec) * 1000.0; 6051 non_young_time_ms += elapsed_ms; 6052 6053 start_sec = os::elapsedTime(); 6054 non_young = false; 6055 } 6056 } else { 6057 if (!cur->is_young()) { 6058 double end_sec = os::elapsedTime(); 6059 double elapsed_ms = (end_sec - start_sec) * 1000.0; 6060 young_time_ms += elapsed_ms; 6061 6062 start_sec = os::elapsedTime(); 6063 non_young = true; 6064 } 6065 } 6066 6067 rs_lengths += cur->rem_set()->occupied_locked(); 6068 6069 HeapRegion* next = cur->next_in_collection_set(); 6070 assert(cur->in_collection_set(), "bad CS"); 6071 cur->set_next_in_collection_set(NULL); 6072 clear_in_cset(cur); 6073 6074 if (cur->is_young()) { 6075 int index = cur->young_index_in_cset(); 6076 assert(index != -1, "invariant"); 6077 assert((uint) index < policy->young_cset_region_length(), "invariant"); 6078 size_t words_survived = _surviving_young_words[index]; 6079 cur->record_surv_words_in_group(words_survived); 6080 6081 // At this point the we have 'popped' cur from the collection set 6082 // (linked via next_in_collection_set()) but it is still in the 6083 // young list (linked via next_young_region()). Clear the 6084 // _next_young_region field. 6085 cur->set_next_young_region(NULL); 6086 } else { 6087 int index = cur->young_index_in_cset(); 6088 assert(index == -1, "invariant"); 6089 } 6090 6091 assert( (cur->is_young() && cur->young_index_in_cset() > -1) || 6092 (!cur->is_young() && cur->young_index_in_cset() == -1), 6093 "invariant" ); 6094 6095 if (!cur->evacuation_failed()) { 6096 MemRegion used_mr = cur->used_region(); 6097 6098 // And the region is empty. 6099 assert(!used_mr.is_empty(), "Should not have empty regions in a CS."); 6100 pre_used += cur->used(); 6101 free_region(cur, &local_free_list, false /* par */, true /* locked */); 6102 } else { 6103 cur->uninstall_surv_rate_group(); 6104 if (cur->is_young()) { 6105 cur->set_young_index_in_cset(-1); 6106 } 6107 cur->set_evacuation_failed(false); 6108 // The region is now considered to be old. 6109 cur->set_old(); 6110 _old_set.add(cur); 6111 evacuation_info.increment_collectionset_used_after(cur->used()); 6112 } 6113 cur = next; 6114 } 6115 6116 evacuation_info.set_regions_freed(local_free_list.length()); 6117 policy->record_max_rs_lengths(rs_lengths); 6118 policy->cset_regions_freed(); 6119 6120 double end_sec = os::elapsedTime(); 6121 double elapsed_ms = (end_sec - start_sec) * 1000.0; 6122 6123 if (non_young) { 6124 non_young_time_ms += elapsed_ms; 6125 } else { 6126 young_time_ms += elapsed_ms; 6127 } 6128 6129 prepend_to_freelist(&local_free_list); 6130 decrement_summary_bytes(pre_used); 6131 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms); 6132 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms); 6133 } 6134 6135 class G1FreeHumongousRegionClosure : public HeapRegionClosure { 6136 private: 6137 FreeRegionList* _free_region_list; 6138 HeapRegionSet* _proxy_set; 6139 HeapRegionSetCount _humongous_regions_removed; 6140 size_t _freed_bytes; 6141 public: 6142 6143 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) : 6144 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) { 6145 } 6146 6147 virtual bool doHeapRegion(HeapRegion* r) { 6148 if (!r->is_starts_humongous()) { 6149 return false; 6150 } 6151 6152 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 6153 6154 oop obj = (oop)r->bottom(); 6155 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap(); 6156 6157 // The following checks whether the humongous object is live are sufficient. 6158 // The main additional check (in addition to having a reference from the roots 6159 // or the young gen) is whether the humongous object has a remembered set entry. 6160 // 6161 // A humongous object cannot be live if there is no remembered set for it 6162 // because: 6163 // - there can be no references from within humongous starts regions referencing 6164 // the object because we never allocate other objects into them. 6165 // (I.e. there are no intra-region references that may be missed by the 6166 // remembered set) 6167 // - as soon there is a remembered set entry to the humongous starts region 6168 // (i.e. it has "escaped" to an old object) this remembered set entry will stay 6169 // until the end of a concurrent mark. 6170 // 6171 // It is not required to check whether the object has been found dead by marking 6172 // or not, in fact it would prevent reclamation within a concurrent cycle, as 6173 // all objects allocated during that time are considered live. 6174 // SATB marking is even more conservative than the remembered set. 6175 // So if at this point in the collection there is no remembered set entry, 6176 // nobody has a reference to it. 6177 // At the start of collection we flush all refinement logs, and remembered sets 6178 // are completely up-to-date wrt to references to the humongous object. 6179 // 6180 // Other implementation considerations: 6181 // - never consider object arrays at this time because they would pose 6182 // considerable effort for cleaning up the the remembered sets. This is 6183 // required because stale remembered sets might reference locations that 6184 // are currently allocated into. 6185 uint region_idx = r->hrm_index(); 6186 if (g1h->humongous_is_live(region_idx) || 6187 g1h->humongous_region_is_always_live(region_idx)) { 6188 6189 if (G1TraceEagerReclaimHumongousObjects) { 6190 gclog_or_tty->print_cr("Live humongous region %u size "SIZE_FORMAT" start "PTR_FORMAT" length "UINT32_FORMAT" with remset "SIZE_FORMAT" code roots "SIZE_FORMAT" is marked %d live-other %d obj array %d", 6191 region_idx, 6192 obj->size()*HeapWordSize, 6193 r->bottom(), 6194 r->region_num(), 6195 r->rem_set()->occupied(), 6196 r->rem_set()->strong_code_roots_list_length(), 6197 next_bitmap->isMarked(r->bottom()), 6198 g1h->humongous_is_live(region_idx), 6199 obj->is_objArray() 6200 ); 6201 } 6202 6203 return false; 6204 } 6205 6206 guarantee(!obj->is_objArray(), 6207 err_msg("Eagerly reclaiming object arrays is not supported, but the object "PTR_FORMAT" is.", 6208 r->bottom())); 6209 6210 if (G1TraceEagerReclaimHumongousObjects) { 6211 gclog_or_tty->print_cr("Dead humongous region %u size "SIZE_FORMAT" start "PTR_FORMAT" length "UINT32_FORMAT" with remset "SIZE_FORMAT" code roots "SIZE_FORMAT" is marked %d live-other %d obj array %d", 6212 region_idx, 6213 obj->size()*HeapWordSize, 6214 r->bottom(), 6215 r->region_num(), 6216 r->rem_set()->occupied(), 6217 r->rem_set()->strong_code_roots_list_length(), 6218 next_bitmap->isMarked(r->bottom()), 6219 g1h->humongous_is_live(region_idx), 6220 obj->is_objArray() 6221 ); 6222 } 6223 // Need to clear mark bit of the humongous object if already set. 6224 if (next_bitmap->isMarked(r->bottom())) { 6225 next_bitmap->clear(r->bottom()); 6226 } 6227 _freed_bytes += r->used(); 6228 r->set_containing_set(NULL); 6229 _humongous_regions_removed.increment(1u, r->capacity()); 6230 g1h->free_humongous_region(r, _free_region_list, false); 6231 6232 return false; 6233 } 6234 6235 HeapRegionSetCount& humongous_free_count() { 6236 return _humongous_regions_removed; 6237 } 6238 6239 size_t bytes_freed() const { 6240 return _freed_bytes; 6241 } 6242 6243 size_t humongous_reclaimed() const { 6244 return _humongous_regions_removed.length(); 6245 } 6246 }; 6247 6248 void G1CollectedHeap::eagerly_reclaim_humongous_regions() { 6249 assert_at_safepoint(true); 6250 6251 if (!G1EagerReclaimHumongousObjects || 6252 (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) { 6253 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0); 6254 return; 6255 } 6256 6257 double start_time = os::elapsedTime(); 6258 6259 FreeRegionList local_cleanup_list("Local Humongous Cleanup List"); 6260 6261 G1FreeHumongousRegionClosure cl(&local_cleanup_list); 6262 heap_region_iterate(&cl); 6263 6264 HeapRegionSetCount empty_set; 6265 remove_from_old_sets(empty_set, cl.humongous_free_count()); 6266 6267 G1HRPrinter* hr_printer = _g1h->hr_printer(); 6268 if (hr_printer->is_active()) { 6269 FreeRegionListIterator iter(&local_cleanup_list); 6270 while (iter.more_available()) { 6271 HeapRegion* hr = iter.get_next(); 6272 hr_printer->cleanup(hr); 6273 } 6274 } 6275 6276 prepend_to_freelist(&local_cleanup_list); 6277 decrement_summary_bytes(cl.bytes_freed()); 6278 6279 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0, 6280 cl.humongous_reclaimed()); 6281 } 6282 6283 // This routine is similar to the above but does not record 6284 // any policy statistics or update free lists; we are abandoning 6285 // the current incremental collection set in preparation of a 6286 // full collection. After the full GC we will start to build up 6287 // the incremental collection set again. 6288 // This is only called when we're doing a full collection 6289 // and is immediately followed by the tearing down of the young list. 6290 6291 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) { 6292 HeapRegion* cur = cs_head; 6293 6294 while (cur != NULL) { 6295 HeapRegion* next = cur->next_in_collection_set(); 6296 assert(cur->in_collection_set(), "bad CS"); 6297 cur->set_next_in_collection_set(NULL); 6298 clear_in_cset(cur); 6299 cur->set_young_index_in_cset(-1); 6300 cur = next; 6301 } 6302 } 6303 6304 void G1CollectedHeap::set_free_regions_coming() { 6305 if (G1ConcRegionFreeingVerbose) { 6306 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " 6307 "setting free regions coming"); 6308 } 6309 6310 assert(!free_regions_coming(), "pre-condition"); 6311 _free_regions_coming = true; 6312 } 6313 6314 void G1CollectedHeap::reset_free_regions_coming() { 6315 assert(free_regions_coming(), "pre-condition"); 6316 6317 { 6318 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6319 _free_regions_coming = false; 6320 SecondaryFreeList_lock->notify_all(); 6321 } 6322 6323 if (G1ConcRegionFreeingVerbose) { 6324 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " 6325 "reset free regions coming"); 6326 } 6327 } 6328 6329 void G1CollectedHeap::wait_while_free_regions_coming() { 6330 // Most of the time we won't have to wait, so let's do a quick test 6331 // first before we take the lock. 6332 if (!free_regions_coming()) { 6333 return; 6334 } 6335 6336 if (G1ConcRegionFreeingVerbose) { 6337 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " 6338 "waiting for free regions"); 6339 } 6340 6341 { 6342 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6343 while (free_regions_coming()) { 6344 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 6345 } 6346 } 6347 6348 if (G1ConcRegionFreeingVerbose) { 6349 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " 6350 "done waiting for free regions"); 6351 } 6352 } 6353 6354 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 6355 assert(heap_lock_held_for_gc(), 6356 "the heap lock should already be held by or for this thread"); 6357 _young_list->push_region(hr); 6358 } 6359 6360 class NoYoungRegionsClosure: public HeapRegionClosure { 6361 private: 6362 bool _success; 6363 public: 6364 NoYoungRegionsClosure() : _success(true) { } 6365 bool doHeapRegion(HeapRegion* r) { 6366 if (r->is_young()) { 6367 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young", 6368 r->bottom(), r->end()); 6369 _success = false; 6370 } 6371 return false; 6372 } 6373 bool success() { return _success; } 6374 }; 6375 6376 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) { 6377 bool ret = _young_list->check_list_empty(check_sample); 6378 6379 if (check_heap) { 6380 NoYoungRegionsClosure closure; 6381 heap_region_iterate(&closure); 6382 ret = ret && closure.success(); 6383 } 6384 6385 return ret; 6386 } 6387 6388 class TearDownRegionSetsClosure : public HeapRegionClosure { 6389 private: 6390 HeapRegionSet *_old_set; 6391 6392 public: 6393 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { } 6394 6395 bool doHeapRegion(HeapRegion* r) { 6396 if (r->is_old()) { 6397 _old_set->remove(r); 6398 } else { 6399 // We ignore free regions, we'll empty the free list afterwards. 6400 // We ignore young regions, we'll empty the young list afterwards. 6401 // We ignore humongous regions, we're not tearing down the 6402 // humongous regions set. 6403 assert(r->is_free() || r->is_young() || r->is_humongous(), 6404 "it cannot be another type"); 6405 } 6406 return false; 6407 } 6408 6409 ~TearDownRegionSetsClosure() { 6410 assert(_old_set->is_empty(), "post-condition"); 6411 } 6412 }; 6413 6414 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) { 6415 assert_at_safepoint(true /* should_be_vm_thread */); 6416 6417 if (!free_list_only) { 6418 TearDownRegionSetsClosure cl(&_old_set); 6419 heap_region_iterate(&cl); 6420 6421 // Note that emptying the _young_list is postponed and instead done as 6422 // the first step when rebuilding the regions sets again. The reason for 6423 // this is that during a full GC string deduplication needs to know if 6424 // a collected region was young or old when the full GC was initiated. 6425 } 6426 _hrm.remove_all_free_regions(); 6427 } 6428 6429 class RebuildRegionSetsClosure : public HeapRegionClosure { 6430 private: 6431 bool _free_list_only; 6432 HeapRegionSet* _old_set; 6433 HeapRegionManager* _hrm; 6434 size_t _total_used; 6435 6436 public: 6437 RebuildRegionSetsClosure(bool free_list_only, 6438 HeapRegionSet* old_set, HeapRegionManager* hrm) : 6439 _free_list_only(free_list_only), 6440 _old_set(old_set), _hrm(hrm), _total_used(0) { 6441 assert(_hrm->num_free_regions() == 0, "pre-condition"); 6442 if (!free_list_only) { 6443 assert(_old_set->is_empty(), "pre-condition"); 6444 } 6445 } 6446 6447 bool doHeapRegion(HeapRegion* r) { 6448 if (r->is_continues_humongous()) { 6449 return false; 6450 } 6451 6452 if (r->is_empty()) { 6453 // Add free regions to the free list 6454 r->set_free(); 6455 r->set_allocation_context(AllocationContext::system()); 6456 _hrm->insert_into_free_list(r); 6457 } else if (!_free_list_only) { 6458 assert(!r->is_young(), "we should not come across young regions"); 6459 6460 if (r->is_humongous()) { 6461 // We ignore humongous regions, we left the humongous set unchanged 6462 } else { 6463 // Objects that were compacted would have ended up on regions 6464 // that were previously old or free. 6465 assert(r->is_free() || r->is_old(), "invariant"); 6466 // We now consider them old, so register as such. 6467 r->set_old(); 6468 _old_set->add(r); 6469 } 6470 _total_used += r->used(); 6471 } 6472 6473 return false; 6474 } 6475 6476 size_t total_used() { 6477 return _total_used; 6478 } 6479 }; 6480 6481 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { 6482 assert_at_safepoint(true /* should_be_vm_thread */); 6483 6484 if (!free_list_only) { 6485 _young_list->empty_list(); 6486 } 6487 6488 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm); 6489 heap_region_iterate(&cl); 6490 6491 if (!free_list_only) { 6492 _allocator->set_used(cl.total_used()); 6493 } 6494 assert(_allocator->used_unlocked() == recalculate_used(), 6495 err_msg("inconsistent _allocator->used_unlocked(), " 6496 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT, 6497 _allocator->used_unlocked(), recalculate_used())); 6498 } 6499 6500 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) { 6501 _refine_cte_cl->set_concurrent(concurrent); 6502 } 6503 6504 bool G1CollectedHeap::is_in_closed_subset(const void* p) const { 6505 HeapRegion* hr = heap_region_containing(p); 6506 return hr->is_in(p); 6507 } 6508 6509 // Methods for the mutator alloc region 6510 6511 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 6512 bool force) { 6513 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6514 assert(!force || g1_policy()->can_expand_young_list(), 6515 "if force is true we should be able to expand the young list"); 6516 bool young_list_full = g1_policy()->is_young_list_full(); 6517 if (force || !young_list_full) { 6518 HeapRegion* new_alloc_region = new_region(word_size, 6519 false /* is_old */, 6520 false /* do_expand */); 6521 if (new_alloc_region != NULL) { 6522 set_region_short_lived_locked(new_alloc_region); 6523 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full); 6524 check_bitmaps("Mutator Region Allocation", new_alloc_region); 6525 return new_alloc_region; 6526 } 6527 } 6528 return NULL; 6529 } 6530 6531 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 6532 size_t allocated_bytes) { 6533 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6534 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden"); 6535 6536 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region); 6537 _allocator->increase_used(allocated_bytes); 6538 _hr_printer.retire(alloc_region); 6539 // We update the eden sizes here, when the region is retired, 6540 // instead of when it's allocated, since this is the point that its 6541 // used space has been recored in _summary_bytes_used. 6542 g1mm()->update_eden_size(); 6543 } 6544 6545 void G1CollectedHeap::set_par_threads() { 6546 // Don't change the number of workers. Use the value previously set 6547 // in the workgroup. 6548 uint n_workers = workers()->active_workers(); 6549 assert(UseDynamicNumberOfGCThreads || 6550 n_workers == workers()->total_workers(), 6551 "Otherwise should be using the total number of workers"); 6552 if (n_workers == 0) { 6553 assert(false, "Should have been set in prior evacuation pause."); 6554 n_workers = ParallelGCThreads; 6555 workers()->set_active_workers(n_workers); 6556 } 6557 set_par_threads(n_workers); 6558 } 6559 6560 // Methods for the GC alloc regions 6561 6562 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, 6563 uint count, 6564 InCSetState dest) { 6565 assert(FreeList_lock->owned_by_self(), "pre-condition"); 6566 6567 if (count < g1_policy()->max_regions(dest)) { 6568 const bool is_survivor = (dest.is_young()); 6569 HeapRegion* new_alloc_region = new_region(word_size, 6570 !is_survivor, 6571 true /* do_expand */); 6572 if (new_alloc_region != NULL) { 6573 // We really only need to do this for old regions given that we 6574 // should never scan survivors. But it doesn't hurt to do it 6575 // for survivors too. 6576 new_alloc_region->record_timestamp(); 6577 if (is_survivor) { 6578 new_alloc_region->set_survivor(); 6579 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor); 6580 check_bitmaps("Survivor Region Allocation", new_alloc_region); 6581 } else { 6582 new_alloc_region->set_old(); 6583 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old); 6584 check_bitmaps("Old Region Allocation", new_alloc_region); 6585 } 6586 bool during_im = g1_policy()->during_initial_mark_pause(); 6587 new_alloc_region->note_start_of_copying(during_im); 6588 return new_alloc_region; 6589 } 6590 } 6591 return NULL; 6592 } 6593 6594 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 6595 size_t allocated_bytes, 6596 InCSetState dest) { 6597 bool during_im = g1_policy()->during_initial_mark_pause(); 6598 alloc_region->note_end_of_copying(during_im); 6599 g1_policy()->record_bytes_copied_during_gc(allocated_bytes); 6600 if (dest.is_young()) { 6601 young_list()->add_survivor_region(alloc_region); 6602 } else { 6603 _old_set.add(alloc_region); 6604 } 6605 _hr_printer.retire(alloc_region); 6606 } 6607 6608 // Heap region set verification 6609 6610 class VerifyRegionListsClosure : public HeapRegionClosure { 6611 private: 6612 HeapRegionSet* _old_set; 6613 HeapRegionSet* _humongous_set; 6614 HeapRegionManager* _hrm; 6615 6616 public: 6617 HeapRegionSetCount _old_count; 6618 HeapRegionSetCount _humongous_count; 6619 HeapRegionSetCount _free_count; 6620 6621 VerifyRegionListsClosure(HeapRegionSet* old_set, 6622 HeapRegionSet* humongous_set, 6623 HeapRegionManager* hrm) : 6624 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm), 6625 _old_count(), _humongous_count(), _free_count(){ } 6626 6627 bool doHeapRegion(HeapRegion* hr) { 6628 if (hr->is_continues_humongous()) { 6629 return false; 6630 } 6631 6632 if (hr->is_young()) { 6633 // TODO 6634 } else if (hr->is_starts_humongous()) { 6635 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrm_index())); 6636 _humongous_count.increment(1u, hr->capacity()); 6637 } else if (hr->is_empty()) { 6638 assert(_hrm->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrm_index())); 6639 _free_count.increment(1u, hr->capacity()); 6640 } else if (hr->is_old()) { 6641 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrm_index())); 6642 _old_count.increment(1u, hr->capacity()); 6643 } else { 6644 ShouldNotReachHere(); 6645 } 6646 return false; 6647 } 6648 6649 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) { 6650 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length())); 6651 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6652 old_set->total_capacity_bytes(), _old_count.capacity())); 6653 6654 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length())); 6655 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6656 humongous_set->total_capacity_bytes(), _humongous_count.capacity())); 6657 6658 guarantee(free_list->num_free_regions() == _free_count.length(), err_msg("Free list count mismatch. Expected %u, actual %u.", free_list->num_free_regions(), _free_count.length())); 6659 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6660 free_list->total_capacity_bytes(), _free_count.capacity())); 6661 } 6662 }; 6663 6664 void G1CollectedHeap::verify_region_sets() { 6665 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6666 6667 // First, check the explicit lists. 6668 _hrm.verify(); 6669 { 6670 // Given that a concurrent operation might be adding regions to 6671 // the secondary free list we have to take the lock before 6672 // verifying it. 6673 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6674 _secondary_free_list.verify_list(); 6675 } 6676 6677 // If a concurrent region freeing operation is in progress it will 6678 // be difficult to correctly attributed any free regions we come 6679 // across to the correct free list given that they might belong to 6680 // one of several (free_list, secondary_free_list, any local lists, 6681 // etc.). So, if that's the case we will skip the rest of the 6682 // verification operation. Alternatively, waiting for the concurrent 6683 // operation to complete will have a non-trivial effect on the GC's 6684 // operation (no concurrent operation will last longer than the 6685 // interval between two calls to verification) and it might hide 6686 // any issues that we would like to catch during testing. 6687 if (free_regions_coming()) { 6688 return; 6689 } 6690 6691 // Make sure we append the secondary_free_list on the free_list so 6692 // that all free regions we will come across can be safely 6693 // attributed to the free_list. 6694 append_secondary_free_list_if_not_empty_with_lock(); 6695 6696 // Finally, make sure that the region accounting in the lists is 6697 // consistent with what we see in the heap. 6698 6699 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm); 6700 heap_region_iterate(&cl); 6701 cl.verify_counts(&_old_set, &_humongous_set, &_hrm); 6702 } 6703 6704 // Optimized nmethod scanning 6705 6706 class RegisterNMethodOopClosure: public OopClosure { 6707 G1CollectedHeap* _g1h; 6708 nmethod* _nm; 6709 6710 template <class T> void do_oop_work(T* p) { 6711 T heap_oop = oopDesc::load_heap_oop(p); 6712 if (!oopDesc::is_null(heap_oop)) { 6713 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 6714 HeapRegion* hr = _g1h->heap_region_containing(obj); 6715 assert(!hr->is_continues_humongous(), 6716 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT 6717 " starting at "HR_FORMAT, 6718 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()))); 6719 6720 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries. 6721 hr->add_strong_code_root_locked(_nm); 6722 } 6723 } 6724 6725 public: 6726 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 6727 _g1h(g1h), _nm(nm) {} 6728 6729 void do_oop(oop* p) { do_oop_work(p); } 6730 void do_oop(narrowOop* p) { do_oop_work(p); } 6731 }; 6732 6733 class UnregisterNMethodOopClosure: public OopClosure { 6734 G1CollectedHeap* _g1h; 6735 nmethod* _nm; 6736 6737 template <class T> void do_oop_work(T* p) { 6738 T heap_oop = oopDesc::load_heap_oop(p); 6739 if (!oopDesc::is_null(heap_oop)) { 6740 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 6741 HeapRegion* hr = _g1h->heap_region_containing(obj); 6742 assert(!hr->is_continues_humongous(), 6743 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT 6744 " starting at "HR_FORMAT, 6745 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()))); 6746 6747 hr->remove_strong_code_root(_nm); 6748 } 6749 } 6750 6751 public: 6752 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 6753 _g1h(g1h), _nm(nm) {} 6754 6755 void do_oop(oop* p) { do_oop_work(p); } 6756 void do_oop(narrowOop* p) { do_oop_work(p); } 6757 }; 6758 6759 void G1CollectedHeap::register_nmethod(nmethod* nm) { 6760 CollectedHeap::register_nmethod(nm); 6761 6762 guarantee(nm != NULL, "sanity"); 6763 RegisterNMethodOopClosure reg_cl(this, nm); 6764 nm->oops_do(®_cl); 6765 } 6766 6767 void G1CollectedHeap::unregister_nmethod(nmethod* nm) { 6768 CollectedHeap::unregister_nmethod(nm); 6769 6770 guarantee(nm != NULL, "sanity"); 6771 UnregisterNMethodOopClosure reg_cl(this, nm); 6772 nm->oops_do(®_cl, true); 6773 } 6774 6775 void G1CollectedHeap::purge_code_root_memory() { 6776 double purge_start = os::elapsedTime(); 6777 G1CodeRootSet::purge(); 6778 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0; 6779 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms); 6780 } 6781 6782 class RebuildStrongCodeRootClosure: public CodeBlobClosure { 6783 G1CollectedHeap* _g1h; 6784 6785 public: 6786 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) : 6787 _g1h(g1h) {} 6788 6789 void do_code_blob(CodeBlob* cb) { 6790 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL; 6791 if (nm == NULL) { 6792 return; 6793 } 6794 6795 if (ScavengeRootsInCode) { 6796 _g1h->register_nmethod(nm); 6797 } 6798 } 6799 }; 6800 6801 void G1CollectedHeap::rebuild_strong_code_roots() { 6802 RebuildStrongCodeRootClosure blob_cl(this); 6803 CodeCache::blobs_do(&blob_cl); 6804 }