1 /* 2 * Copyright (c) 2001, 2014, 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 (unsigned int 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 unsigned int dummy_gc_count_before; 769 int 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 (int try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 780 unsigned int 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 unsigned int *gc_count_before_ret, 833 int* 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 unsigned int 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 unsigned int * gc_count_before_ret, 949 int* 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 unsigned int 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(unsigned int, 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 // In case we're keeping closure specialization stats, initialize those 2030 // counts and that mechanism. 2031 SpecializationStats::clear(); 2032 2033 // Here we allocate the dummy HeapRegion that is required by the 2034 // G1AllocRegion class. 2035 HeapRegion* dummy_region = _hrm.get_dummy_region(); 2036 2037 // We'll re-use the same region whether the alloc region will 2038 // require BOT updates or not and, if it doesn't, then a non-young 2039 // region will complain that it cannot support allocations without 2040 // BOT updates. So we'll tag the dummy region as eden to avoid that. 2041 dummy_region->set_eden(); 2042 // Make sure it's full. 2043 dummy_region->set_top(dummy_region->end()); 2044 G1AllocRegion::setup(this, dummy_region); 2045 2046 _allocator->init_mutator_alloc_region(); 2047 2048 // Do create of the monitoring and management support so that 2049 // values in the heap have been properly initialized. 2050 _g1mm = new G1MonitoringSupport(this); 2051 2052 G1StringDedup::initialize(); 2053 2054 return JNI_OK; 2055 } 2056 2057 void G1CollectedHeap::stop() { 2058 // Stop all concurrent threads. We do this to make sure these threads 2059 // do not continue to execute and access resources (e.g. gclog_or_tty) 2060 // that are destroyed during shutdown. 2061 _cg1r->stop(); 2062 _cmThread->stop(); 2063 if (G1StringDedup::is_enabled()) { 2064 G1StringDedup::stop(); 2065 } 2066 } 2067 2068 void G1CollectedHeap::clear_humongous_is_live_table() { 2069 guarantee(G1EagerReclaimHumongousObjects, "Should only be called if true"); 2070 _humongous_is_live.clear(); 2071 } 2072 2073 size_t G1CollectedHeap::conservative_max_heap_alignment() { 2074 return HeapRegion::max_region_size(); 2075 } 2076 2077 void G1CollectedHeap::ref_processing_init() { 2078 // Reference processing in G1 currently works as follows: 2079 // 2080 // * There are two reference processor instances. One is 2081 // used to record and process discovered references 2082 // during concurrent marking; the other is used to 2083 // record and process references during STW pauses 2084 // (both full and incremental). 2085 // * Both ref processors need to 'span' the entire heap as 2086 // the regions in the collection set may be dotted around. 2087 // 2088 // * For the concurrent marking ref processor: 2089 // * Reference discovery is enabled at initial marking. 2090 // * Reference discovery is disabled and the discovered 2091 // references processed etc during remarking. 2092 // * Reference discovery is MT (see below). 2093 // * Reference discovery requires a barrier (see below). 2094 // * Reference processing may or may not be MT 2095 // (depending on the value of ParallelRefProcEnabled 2096 // and ParallelGCThreads). 2097 // * A full GC disables reference discovery by the CM 2098 // ref processor and abandons any entries on it's 2099 // discovered lists. 2100 // 2101 // * For the STW processor: 2102 // * Non MT discovery is enabled at the start of a full GC. 2103 // * Processing and enqueueing during a full GC is non-MT. 2104 // * During a full GC, references are processed after marking. 2105 // 2106 // * Discovery (may or may not be MT) is enabled at the start 2107 // of an incremental evacuation pause. 2108 // * References are processed near the end of a STW evacuation pause. 2109 // * For both types of GC: 2110 // * Discovery is atomic - i.e. not concurrent. 2111 // * Reference discovery will not need a barrier. 2112 2113 SharedHeap::ref_processing_init(); 2114 MemRegion mr = reserved_region(); 2115 2116 // Concurrent Mark ref processor 2117 _ref_processor_cm = 2118 new ReferenceProcessor(mr, // span 2119 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2120 // mt processing 2121 (int) ParallelGCThreads, 2122 // degree of mt processing 2123 (ParallelGCThreads > 1) || (ConcGCThreads > 1), 2124 // mt discovery 2125 (int) MAX2(ParallelGCThreads, ConcGCThreads), 2126 // degree of mt discovery 2127 false, 2128 // Reference discovery is not atomic 2129 &_is_alive_closure_cm); 2130 // is alive closure 2131 // (for efficiency/performance) 2132 2133 // STW ref processor 2134 _ref_processor_stw = 2135 new ReferenceProcessor(mr, // span 2136 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2137 // mt processing 2138 MAX2((int)ParallelGCThreads, 1), 2139 // degree of mt processing 2140 (ParallelGCThreads > 1), 2141 // mt discovery 2142 MAX2((int)ParallelGCThreads, 1), 2143 // degree of mt discovery 2144 true, 2145 // Reference discovery is atomic 2146 &_is_alive_closure_stw); 2147 // is alive closure 2148 // (for efficiency/performance) 2149 } 2150 2151 size_t G1CollectedHeap::capacity() const { 2152 return _hrm.length() * HeapRegion::GrainBytes; 2153 } 2154 2155 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) { 2156 assert(!hr->is_continues_humongous(), "pre-condition"); 2157 hr->reset_gc_time_stamp(); 2158 if (hr->is_starts_humongous()) { 2159 uint first_index = hr->hrm_index() + 1; 2160 uint last_index = hr->last_hc_index(); 2161 for (uint i = first_index; i < last_index; i += 1) { 2162 HeapRegion* chr = region_at(i); 2163 assert(chr->is_continues_humongous(), "sanity"); 2164 chr->reset_gc_time_stamp(); 2165 } 2166 } 2167 } 2168 2169 #ifndef PRODUCT 2170 class CheckGCTimeStampsHRClosure : public HeapRegionClosure { 2171 private: 2172 unsigned _gc_time_stamp; 2173 bool _failures; 2174 2175 public: 2176 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) : 2177 _gc_time_stamp(gc_time_stamp), _failures(false) { } 2178 2179 virtual bool doHeapRegion(HeapRegion* hr) { 2180 unsigned region_gc_time_stamp = hr->get_gc_time_stamp(); 2181 if (_gc_time_stamp != region_gc_time_stamp) { 2182 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, " 2183 "expected %d", HR_FORMAT_PARAMS(hr), 2184 region_gc_time_stamp, _gc_time_stamp); 2185 _failures = true; 2186 } 2187 return false; 2188 } 2189 2190 bool failures() { return _failures; } 2191 }; 2192 2193 void G1CollectedHeap::check_gc_time_stamps() { 2194 CheckGCTimeStampsHRClosure cl(_gc_time_stamp); 2195 heap_region_iterate(&cl); 2196 guarantee(!cl.failures(), "all GC time stamps should have been reset"); 2197 } 2198 #endif // PRODUCT 2199 2200 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, 2201 DirtyCardQueue* into_cset_dcq, 2202 bool concurrent, 2203 uint worker_i) { 2204 // Clean cards in the hot card cache 2205 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 2206 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq); 2207 2208 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 2209 int n_completed_buffers = 0; 2210 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) { 2211 n_completed_buffers++; 2212 } 2213 g1_policy()->phase_times()->record_update_rs_processed_buffers(worker_i, n_completed_buffers); 2214 dcqs.clear_n_completed_buffers(); 2215 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!"); 2216 } 2217 2218 2219 // Computes the sum of the storage used by the various regions. 2220 size_t G1CollectedHeap::used() const { 2221 return _allocator->used(); 2222 } 2223 2224 size_t G1CollectedHeap::used_unlocked() const { 2225 return _allocator->used_unlocked(); 2226 } 2227 2228 class SumUsedClosure: public HeapRegionClosure { 2229 size_t _used; 2230 public: 2231 SumUsedClosure() : _used(0) {} 2232 bool doHeapRegion(HeapRegion* r) { 2233 if (!r->is_continues_humongous()) { 2234 _used += r->used(); 2235 } 2236 return false; 2237 } 2238 size_t result() { return _used; } 2239 }; 2240 2241 size_t G1CollectedHeap::recalculate_used() const { 2242 double recalculate_used_start = os::elapsedTime(); 2243 2244 SumUsedClosure blk; 2245 heap_region_iterate(&blk); 2246 2247 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0); 2248 return blk.result(); 2249 } 2250 2251 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 2252 switch (cause) { 2253 case GCCause::_gc_locker: return GCLockerInvokesConcurrent; 2254 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent; 2255 case GCCause::_g1_humongous_allocation: return true; 2256 case GCCause::_update_allocation_context_stats_inc: return true; 2257 case GCCause::_wb_conc_mark: return true; 2258 default: return false; 2259 } 2260 } 2261 2262 #ifndef PRODUCT 2263 void G1CollectedHeap::allocate_dummy_regions() { 2264 // Let's fill up most of the region 2265 size_t word_size = HeapRegion::GrainWords - 1024; 2266 // And as a result the region we'll allocate will be humongous. 2267 guarantee(is_humongous(word_size), "sanity"); 2268 2269 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) { 2270 // Let's use the existing mechanism for the allocation 2271 HeapWord* dummy_obj = humongous_obj_allocate(word_size, 2272 AllocationContext::system()); 2273 if (dummy_obj != NULL) { 2274 MemRegion mr(dummy_obj, word_size); 2275 CollectedHeap::fill_with_object(mr); 2276 } else { 2277 // If we can't allocate once, we probably cannot allocate 2278 // again. Let's get out of the loop. 2279 break; 2280 } 2281 } 2282 } 2283 #endif // !PRODUCT 2284 2285 void G1CollectedHeap::increment_old_marking_cycles_started() { 2286 assert(_old_marking_cycles_started == _old_marking_cycles_completed || 2287 _old_marking_cycles_started == _old_marking_cycles_completed + 1, 2288 err_msg("Wrong marking cycle count (started: %d, completed: %d)", 2289 _old_marking_cycles_started, _old_marking_cycles_completed)); 2290 2291 _old_marking_cycles_started++; 2292 } 2293 2294 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) { 2295 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 2296 2297 // We assume that if concurrent == true, then the caller is a 2298 // concurrent thread that was joined the Suspendible Thread 2299 // Set. If there's ever a cheap way to check this, we should add an 2300 // assert here. 2301 2302 // Given that this method is called at the end of a Full GC or of a 2303 // concurrent cycle, and those can be nested (i.e., a Full GC can 2304 // interrupt a concurrent cycle), the number of full collections 2305 // completed should be either one (in the case where there was no 2306 // nesting) or two (when a Full GC interrupted a concurrent cycle) 2307 // behind the number of full collections started. 2308 2309 // This is the case for the inner caller, i.e. a Full GC. 2310 assert(concurrent || 2311 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || 2312 (_old_marking_cycles_started == _old_marking_cycles_completed + 2), 2313 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u " 2314 "is inconsistent with _old_marking_cycles_completed = %u", 2315 _old_marking_cycles_started, _old_marking_cycles_completed)); 2316 2317 // This is the case for the outer caller, i.e. the concurrent cycle. 2318 assert(!concurrent || 2319 (_old_marking_cycles_started == _old_marking_cycles_completed + 1), 2320 err_msg("for outer caller (concurrent cycle): " 2321 "_old_marking_cycles_started = %u " 2322 "is inconsistent with _old_marking_cycles_completed = %u", 2323 _old_marking_cycles_started, _old_marking_cycles_completed)); 2324 2325 _old_marking_cycles_completed += 1; 2326 2327 // We need to clear the "in_progress" flag in the CM thread before 2328 // we wake up any waiters (especially when ExplicitInvokesConcurrent 2329 // is set) so that if a waiter requests another System.gc() it doesn't 2330 // incorrectly see that a marking cycle is still in progress. 2331 if (concurrent) { 2332 _cmThread->clear_in_progress(); 2333 } 2334 2335 // This notify_all() will ensure that a thread that called 2336 // System.gc() with (with ExplicitGCInvokesConcurrent set or not) 2337 // and it's waiting for a full GC to finish will be woken up. It is 2338 // waiting in VM_G1IncCollectionPause::doit_epilogue(). 2339 FullGCCount_lock->notify_all(); 2340 } 2341 2342 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) { 2343 _concurrent_cycle_started = true; 2344 _gc_timer_cm->register_gc_start(start_time); 2345 2346 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start()); 2347 trace_heap_before_gc(_gc_tracer_cm); 2348 } 2349 2350 void G1CollectedHeap::register_concurrent_cycle_end() { 2351 if (_concurrent_cycle_started) { 2352 if (_cm->has_aborted()) { 2353 _gc_tracer_cm->report_concurrent_mode_failure(); 2354 } 2355 2356 _gc_timer_cm->register_gc_end(); 2357 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions()); 2358 2359 // Clear state variables to prepare for the next concurrent cycle. 2360 _concurrent_cycle_started = false; 2361 _heap_summary_sent = false; 2362 } 2363 } 2364 2365 void G1CollectedHeap::trace_heap_after_concurrent_cycle() { 2366 if (_concurrent_cycle_started) { 2367 // This function can be called when: 2368 // the cleanup pause is run 2369 // the concurrent cycle is aborted before the cleanup pause. 2370 // the concurrent cycle is aborted after the cleanup pause, 2371 // but before the concurrent cycle end has been registered. 2372 // Make sure that we only send the heap information once. 2373 if (!_heap_summary_sent) { 2374 trace_heap_after_gc(_gc_tracer_cm); 2375 _heap_summary_sent = true; 2376 } 2377 } 2378 } 2379 2380 G1YCType G1CollectedHeap::yc_type() { 2381 bool is_young = g1_policy()->gcs_are_young(); 2382 bool is_initial_mark = g1_policy()->during_initial_mark_pause(); 2383 bool is_during_mark = mark_in_progress(); 2384 2385 if (is_initial_mark) { 2386 return InitialMark; 2387 } else if (is_during_mark) { 2388 return DuringMark; 2389 } else if (is_young) { 2390 return Normal; 2391 } else { 2392 return Mixed; 2393 } 2394 } 2395 2396 void G1CollectedHeap::collect(GCCause::Cause cause) { 2397 assert_heap_not_locked(); 2398 2399 unsigned int gc_count_before; 2400 unsigned int old_marking_count_before; 2401 unsigned int full_gc_count_before; 2402 bool retry_gc; 2403 2404 do { 2405 retry_gc = false; 2406 2407 { 2408 MutexLocker ml(Heap_lock); 2409 2410 // Read the GC count while holding the Heap_lock 2411 gc_count_before = total_collections(); 2412 full_gc_count_before = total_full_collections(); 2413 old_marking_count_before = _old_marking_cycles_started; 2414 } 2415 2416 if (should_do_concurrent_full_gc(cause)) { 2417 // Schedule an initial-mark evacuation pause that will start a 2418 // concurrent cycle. We're setting word_size to 0 which means that 2419 // we are not requesting a post-GC allocation. 2420 VM_G1IncCollectionPause op(gc_count_before, 2421 0, /* word_size */ 2422 true, /* should_initiate_conc_mark */ 2423 g1_policy()->max_pause_time_ms(), 2424 cause); 2425 op.set_allocation_context(AllocationContext::current()); 2426 2427 VMThread::execute(&op); 2428 if (!op.pause_succeeded()) { 2429 if (old_marking_count_before == _old_marking_cycles_started) { 2430 retry_gc = op.should_retry_gc(); 2431 } else { 2432 // A Full GC happened while we were trying to schedule the 2433 // initial-mark GC. No point in starting a new cycle given 2434 // that the whole heap was collected anyway. 2435 } 2436 2437 if (retry_gc) { 2438 if (GC_locker::is_active_and_needs_gc()) { 2439 GC_locker::stall_until_clear(); 2440 } 2441 } 2442 } 2443 } else { 2444 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc 2445 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { 2446 2447 // Schedule a standard evacuation pause. We're setting word_size 2448 // to 0 which means that we are not requesting a post-GC allocation. 2449 VM_G1IncCollectionPause op(gc_count_before, 2450 0, /* word_size */ 2451 false, /* should_initiate_conc_mark */ 2452 g1_policy()->max_pause_time_ms(), 2453 cause); 2454 VMThread::execute(&op); 2455 } else { 2456 // Schedule a Full GC. 2457 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause); 2458 VMThread::execute(&op); 2459 } 2460 } 2461 } while (retry_gc); 2462 } 2463 2464 bool G1CollectedHeap::is_in(const void* p) const { 2465 if (_hrm.reserved().contains(p)) { 2466 // Given that we know that p is in the reserved space, 2467 // heap_region_containing_raw() should successfully 2468 // return the containing region. 2469 HeapRegion* hr = heap_region_containing_raw(p); 2470 return hr->is_in(p); 2471 } else { 2472 return false; 2473 } 2474 } 2475 2476 #ifdef ASSERT 2477 bool G1CollectedHeap::is_in_exact(const void* p) const { 2478 bool contains = reserved_region().contains(p); 2479 bool available = _hrm.is_available(addr_to_region((HeapWord*)p)); 2480 if (contains && available) { 2481 return true; 2482 } else { 2483 return false; 2484 } 2485 } 2486 #endif 2487 2488 // Iteration functions. 2489 2490 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion. 2491 2492 class IterateOopClosureRegionClosure: public HeapRegionClosure { 2493 ExtendedOopClosure* _cl; 2494 public: 2495 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {} 2496 bool doHeapRegion(HeapRegion* r) { 2497 if (!r->is_continues_humongous()) { 2498 r->oop_iterate(_cl); 2499 } 2500 return false; 2501 } 2502 }; 2503 2504 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) { 2505 IterateOopClosureRegionClosure blk(cl); 2506 heap_region_iterate(&blk); 2507 } 2508 2509 // Iterates an ObjectClosure over all objects within a HeapRegion. 2510 2511 class IterateObjectClosureRegionClosure: public HeapRegionClosure { 2512 ObjectClosure* _cl; 2513 public: 2514 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} 2515 bool doHeapRegion(HeapRegion* r) { 2516 if (!r->is_continues_humongous()) { 2517 r->object_iterate(_cl); 2518 } 2519 return false; 2520 } 2521 }; 2522 2523 void G1CollectedHeap::object_iterate(ObjectClosure* cl) { 2524 IterateObjectClosureRegionClosure blk(cl); 2525 heap_region_iterate(&blk); 2526 } 2527 2528 // Calls a SpaceClosure on a HeapRegion. 2529 2530 class SpaceClosureRegionClosure: public HeapRegionClosure { 2531 SpaceClosure* _cl; 2532 public: 2533 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {} 2534 bool doHeapRegion(HeapRegion* r) { 2535 _cl->do_space(r); 2536 return false; 2537 } 2538 }; 2539 2540 void G1CollectedHeap::space_iterate(SpaceClosure* cl) { 2541 SpaceClosureRegionClosure blk(cl); 2542 heap_region_iterate(&blk); 2543 } 2544 2545 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { 2546 _hrm.iterate(cl); 2547 } 2548 2549 void 2550 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl, 2551 uint worker_id, 2552 HeapRegionClaimer *hrclaimer, 2553 bool concurrent) const { 2554 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent); 2555 } 2556 2557 // Clear the cached CSet starting regions and (more importantly) 2558 // the time stamps. Called when we reset the GC time stamp. 2559 void G1CollectedHeap::clear_cset_start_regions() { 2560 assert(_worker_cset_start_region != NULL, "sanity"); 2561 assert(_worker_cset_start_region_time_stamp != NULL, "sanity"); 2562 2563 int n_queues = MAX2((int)ParallelGCThreads, 1); 2564 for (int i = 0; i < n_queues; i++) { 2565 _worker_cset_start_region[i] = NULL; 2566 _worker_cset_start_region_time_stamp[i] = 0; 2567 } 2568 } 2569 2570 // Given the id of a worker, obtain or calculate a suitable 2571 // starting region for iterating over the current collection set. 2572 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) { 2573 assert(get_gc_time_stamp() > 0, "should have been updated by now"); 2574 2575 HeapRegion* result = NULL; 2576 unsigned gc_time_stamp = get_gc_time_stamp(); 2577 2578 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) { 2579 // Cached starting region for current worker was set 2580 // during the current pause - so it's valid. 2581 // Note: the cached starting heap region may be NULL 2582 // (when the collection set is empty). 2583 result = _worker_cset_start_region[worker_i]; 2584 assert(result == NULL || result->in_collection_set(), "sanity"); 2585 return result; 2586 } 2587 2588 // The cached entry was not valid so let's calculate 2589 // a suitable starting heap region for this worker. 2590 2591 // We want the parallel threads to start their collection 2592 // set iteration at different collection set regions to 2593 // avoid contention. 2594 // If we have: 2595 // n collection set regions 2596 // p threads 2597 // Then thread t will start at region floor ((t * n) / p) 2598 2599 result = g1_policy()->collection_set(); 2600 uint cs_size = g1_policy()->cset_region_length(); 2601 uint active_workers = workers()->active_workers(); 2602 assert(UseDynamicNumberOfGCThreads || 2603 active_workers == workers()->total_workers(), 2604 "Unless dynamic should use total workers"); 2605 2606 uint end_ind = (cs_size * worker_i) / active_workers; 2607 uint start_ind = 0; 2608 2609 if (worker_i > 0 && 2610 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) { 2611 // Previous workers starting region is valid 2612 // so let's iterate from there 2613 start_ind = (cs_size * (worker_i - 1)) / active_workers; 2614 result = _worker_cset_start_region[worker_i - 1]; 2615 } 2616 2617 for (uint i = start_ind; i < end_ind; i++) { 2618 result = result->next_in_collection_set(); 2619 } 2620 2621 // Note: the calculated starting heap region may be NULL 2622 // (when the collection set is empty). 2623 assert(result == NULL || result->in_collection_set(), "sanity"); 2624 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp, 2625 "should be updated only once per pause"); 2626 _worker_cset_start_region[worker_i] = result; 2627 OrderAccess::storestore(); 2628 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp; 2629 return result; 2630 } 2631 2632 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) { 2633 HeapRegion* r = g1_policy()->collection_set(); 2634 while (r != NULL) { 2635 HeapRegion* next = r->next_in_collection_set(); 2636 if (cl->doHeapRegion(r)) { 2637 cl->incomplete(); 2638 return; 2639 } 2640 r = next; 2641 } 2642 } 2643 2644 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r, 2645 HeapRegionClosure *cl) { 2646 if (r == NULL) { 2647 // The CSet is empty so there's nothing to do. 2648 return; 2649 } 2650 2651 assert(r->in_collection_set(), 2652 "Start region must be a member of the collection set."); 2653 HeapRegion* cur = r; 2654 while (cur != NULL) { 2655 HeapRegion* next = cur->next_in_collection_set(); 2656 if (cl->doHeapRegion(cur) && false) { 2657 cl->incomplete(); 2658 return; 2659 } 2660 cur = next; 2661 } 2662 cur = g1_policy()->collection_set(); 2663 while (cur != r) { 2664 HeapRegion* next = cur->next_in_collection_set(); 2665 if (cl->doHeapRegion(cur) && false) { 2666 cl->incomplete(); 2667 return; 2668 } 2669 cur = next; 2670 } 2671 } 2672 2673 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const { 2674 HeapRegion* result = _hrm.next_region_in_heap(from); 2675 while (result != NULL && result->is_humongous()) { 2676 result = _hrm.next_region_in_heap(result); 2677 } 2678 return result; 2679 } 2680 2681 Space* G1CollectedHeap::space_containing(const void* addr) const { 2682 return heap_region_containing(addr); 2683 } 2684 2685 HeapWord* G1CollectedHeap::block_start(const void* addr) const { 2686 Space* sp = space_containing(addr); 2687 return sp->block_start(addr); 2688 } 2689 2690 size_t G1CollectedHeap::block_size(const HeapWord* addr) const { 2691 Space* sp = space_containing(addr); 2692 return sp->block_size(addr); 2693 } 2694 2695 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { 2696 Space* sp = space_containing(addr); 2697 return sp->block_is_obj(addr); 2698 } 2699 2700 bool G1CollectedHeap::supports_tlab_allocation() const { 2701 return true; 2702 } 2703 2704 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { 2705 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes; 2706 } 2707 2708 size_t G1CollectedHeap::tlab_used(Thread* ignored) const { 2709 return young_list()->eden_used_bytes(); 2710 } 2711 2712 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size 2713 // must be smaller than the humongous object limit. 2714 size_t G1CollectedHeap::max_tlab_size() const { 2715 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment); 2716 } 2717 2718 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { 2719 // Return the remaining space in the cur alloc region, but not less than 2720 // the min TLAB size. 2721 2722 // Also, this value can be at most the humongous object threshold, 2723 // since we can't allow tlabs to grow big enough to accommodate 2724 // humongous objects. 2725 2726 HeapRegion* hr = _allocator->mutator_alloc_region(AllocationContext::current())->get(); 2727 size_t max_tlab = max_tlab_size() * wordSize; 2728 if (hr == NULL) { 2729 return max_tlab; 2730 } else { 2731 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab); 2732 } 2733 } 2734 2735 size_t G1CollectedHeap::max_capacity() const { 2736 return _hrm.reserved().byte_size(); 2737 } 2738 2739 jlong G1CollectedHeap::millis_since_last_gc() { 2740 // assert(false, "NYI"); 2741 return 0; 2742 } 2743 2744 void G1CollectedHeap::prepare_for_verify() { 2745 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) { 2746 ensure_parsability(false); 2747 } 2748 g1_rem_set()->prepare_for_verify(); 2749 } 2750 2751 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr, 2752 VerifyOption vo) { 2753 switch (vo) { 2754 case VerifyOption_G1UsePrevMarking: 2755 return hr->obj_allocated_since_prev_marking(obj); 2756 case VerifyOption_G1UseNextMarking: 2757 return hr->obj_allocated_since_next_marking(obj); 2758 case VerifyOption_G1UseMarkWord: 2759 return false; 2760 default: 2761 ShouldNotReachHere(); 2762 } 2763 return false; // keep some compilers happy 2764 } 2765 2766 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) { 2767 switch (vo) { 2768 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start(); 2769 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start(); 2770 case VerifyOption_G1UseMarkWord: return NULL; 2771 default: ShouldNotReachHere(); 2772 } 2773 return NULL; // keep some compilers happy 2774 } 2775 2776 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) { 2777 switch (vo) { 2778 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj); 2779 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj); 2780 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked(); 2781 default: ShouldNotReachHere(); 2782 } 2783 return false; // keep some compilers happy 2784 } 2785 2786 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) { 2787 switch (vo) { 2788 case VerifyOption_G1UsePrevMarking: return "PTAMS"; 2789 case VerifyOption_G1UseNextMarking: return "NTAMS"; 2790 case VerifyOption_G1UseMarkWord: return "NONE"; 2791 default: ShouldNotReachHere(); 2792 } 2793 return NULL; // keep some compilers happy 2794 } 2795 2796 class VerifyRootsClosure: public OopClosure { 2797 private: 2798 G1CollectedHeap* _g1h; 2799 VerifyOption _vo; 2800 bool _failures; 2801 public: 2802 // _vo == UsePrevMarking -> use "prev" marking information, 2803 // _vo == UseNextMarking -> use "next" marking information, 2804 // _vo == UseMarkWord -> use mark word from object header. 2805 VerifyRootsClosure(VerifyOption vo) : 2806 _g1h(G1CollectedHeap::heap()), 2807 _vo(vo), 2808 _failures(false) { } 2809 2810 bool failures() { return _failures; } 2811 2812 template <class T> void do_oop_nv(T* p) { 2813 T heap_oop = oopDesc::load_heap_oop(p); 2814 if (!oopDesc::is_null(heap_oop)) { 2815 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 2816 if (_g1h->is_obj_dead_cond(obj, _vo)) { 2817 gclog_or_tty->print_cr("Root location "PTR_FORMAT" " 2818 "points to dead obj "PTR_FORMAT, p, (void*) obj); 2819 if (_vo == VerifyOption_G1UseMarkWord) { 2820 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark())); 2821 } 2822 obj->print_on(gclog_or_tty); 2823 _failures = true; 2824 } 2825 } 2826 } 2827 2828 void do_oop(oop* p) { do_oop_nv(p); } 2829 void do_oop(narrowOop* p) { do_oop_nv(p); } 2830 }; 2831 2832 class G1VerifyCodeRootOopClosure: public OopClosure { 2833 G1CollectedHeap* _g1h; 2834 OopClosure* _root_cl; 2835 nmethod* _nm; 2836 VerifyOption _vo; 2837 bool _failures; 2838 2839 template <class T> void do_oop_work(T* p) { 2840 // First verify that this root is live 2841 _root_cl->do_oop(p); 2842 2843 if (!G1VerifyHeapRegionCodeRoots) { 2844 // We're not verifying the code roots attached to heap region. 2845 return; 2846 } 2847 2848 // Don't check the code roots during marking verification in a full GC 2849 if (_vo == VerifyOption_G1UseMarkWord) { 2850 return; 2851 } 2852 2853 // Now verify that the current nmethod (which contains p) is 2854 // in the code root list of the heap region containing the 2855 // object referenced by p. 2856 2857 T heap_oop = oopDesc::load_heap_oop(p); 2858 if (!oopDesc::is_null(heap_oop)) { 2859 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 2860 2861 // Now fetch the region containing the object 2862 HeapRegion* hr = _g1h->heap_region_containing(obj); 2863 HeapRegionRemSet* hrrs = hr->rem_set(); 2864 // Verify that the strong code root list for this region 2865 // contains the nmethod 2866 if (!hrrs->strong_code_roots_list_contains(_nm)) { 2867 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" " 2868 "from nmethod "PTR_FORMAT" not in strong " 2869 "code roots for region ["PTR_FORMAT","PTR_FORMAT")", 2870 p, _nm, hr->bottom(), hr->end()); 2871 _failures = true; 2872 } 2873 } 2874 } 2875 2876 public: 2877 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo): 2878 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {} 2879 2880 void do_oop(oop* p) { do_oop_work(p); } 2881 void do_oop(narrowOop* p) { do_oop_work(p); } 2882 2883 void set_nmethod(nmethod* nm) { _nm = nm; } 2884 bool failures() { return _failures; } 2885 }; 2886 2887 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure { 2888 G1VerifyCodeRootOopClosure* _oop_cl; 2889 2890 public: 2891 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl): 2892 _oop_cl(oop_cl) {} 2893 2894 void do_code_blob(CodeBlob* cb) { 2895 nmethod* nm = cb->as_nmethod_or_null(); 2896 if (nm != NULL) { 2897 _oop_cl->set_nmethod(nm); 2898 nm->oops_do(_oop_cl); 2899 } 2900 } 2901 }; 2902 2903 class YoungRefCounterClosure : public OopClosure { 2904 G1CollectedHeap* _g1h; 2905 int _count; 2906 public: 2907 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {} 2908 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } } 2909 void do_oop(narrowOop* p) { ShouldNotReachHere(); } 2910 2911 int count() { return _count; } 2912 void reset_count() { _count = 0; }; 2913 }; 2914 2915 class VerifyKlassClosure: public KlassClosure { 2916 YoungRefCounterClosure _young_ref_counter_closure; 2917 OopClosure *_oop_closure; 2918 public: 2919 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {} 2920 void do_klass(Klass* k) { 2921 k->oops_do(_oop_closure); 2922 2923 _young_ref_counter_closure.reset_count(); 2924 k->oops_do(&_young_ref_counter_closure); 2925 if (_young_ref_counter_closure.count() > 0) { 2926 guarantee(k->has_modified_oops(), err_msg("Klass " PTR_FORMAT ", has young refs but is not dirty.", k)); 2927 } 2928 } 2929 }; 2930 2931 class VerifyLivenessOopClosure: public OopClosure { 2932 G1CollectedHeap* _g1h; 2933 VerifyOption _vo; 2934 public: 2935 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo): 2936 _g1h(g1h), _vo(vo) 2937 { } 2938 void do_oop(narrowOop *p) { do_oop_work(p); } 2939 void do_oop( oop *p) { do_oop_work(p); } 2940 2941 template <class T> void do_oop_work(T *p) { 2942 oop obj = oopDesc::load_decode_heap_oop(p); 2943 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo), 2944 "Dead object referenced by a not dead object"); 2945 } 2946 }; 2947 2948 class VerifyObjsInRegionClosure: public ObjectClosure { 2949 private: 2950 G1CollectedHeap* _g1h; 2951 size_t _live_bytes; 2952 HeapRegion *_hr; 2953 VerifyOption _vo; 2954 public: 2955 // _vo == UsePrevMarking -> use "prev" marking information, 2956 // _vo == UseNextMarking -> use "next" marking information, 2957 // _vo == UseMarkWord -> use mark word from object header. 2958 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo) 2959 : _live_bytes(0), _hr(hr), _vo(vo) { 2960 _g1h = G1CollectedHeap::heap(); 2961 } 2962 void do_object(oop o) { 2963 VerifyLivenessOopClosure isLive(_g1h, _vo); 2964 assert(o != NULL, "Huh?"); 2965 if (!_g1h->is_obj_dead_cond(o, _vo)) { 2966 // If the object is alive according to the mark word, 2967 // then verify that the marking information agrees. 2968 // Note we can't verify the contra-positive of the 2969 // above: if the object is dead (according to the mark 2970 // word), it may not be marked, or may have been marked 2971 // but has since became dead, or may have been allocated 2972 // since the last marking. 2973 if (_vo == VerifyOption_G1UseMarkWord) { 2974 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch"); 2975 } 2976 2977 o->oop_iterate_no_header(&isLive); 2978 if (!_hr->obj_allocated_since_prev_marking(o)) { 2979 size_t obj_size = o->size(); // Make sure we don't overflow 2980 _live_bytes += (obj_size * HeapWordSize); 2981 } 2982 } 2983 } 2984 size_t live_bytes() { return _live_bytes; } 2985 }; 2986 2987 class PrintObjsInRegionClosure : public ObjectClosure { 2988 HeapRegion *_hr; 2989 G1CollectedHeap *_g1; 2990 public: 2991 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) { 2992 _g1 = G1CollectedHeap::heap(); 2993 }; 2994 2995 void do_object(oop o) { 2996 if (o != NULL) { 2997 HeapWord *start = (HeapWord *) o; 2998 size_t word_sz = o->size(); 2999 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT 3000 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n", 3001 (void*) o, word_sz, 3002 _g1->isMarkedPrev(o), 3003 _g1->isMarkedNext(o), 3004 _hr->obj_allocated_since_prev_marking(o)); 3005 HeapWord *end = start + word_sz; 3006 HeapWord *cur; 3007 int *val; 3008 for (cur = start; cur < end; cur++) { 3009 val = (int *) cur; 3010 gclog_or_tty->print("\t "PTR_FORMAT":%d\n", val, *val); 3011 } 3012 } 3013 } 3014 }; 3015 3016 class VerifyRegionClosure: public HeapRegionClosure { 3017 private: 3018 bool _par; 3019 VerifyOption _vo; 3020 bool _failures; 3021 public: 3022 // _vo == UsePrevMarking -> use "prev" marking information, 3023 // _vo == UseNextMarking -> use "next" marking information, 3024 // _vo == UseMarkWord -> use mark word from object header. 3025 VerifyRegionClosure(bool par, VerifyOption vo) 3026 : _par(par), 3027 _vo(vo), 3028 _failures(false) {} 3029 3030 bool failures() { 3031 return _failures; 3032 } 3033 3034 bool doHeapRegion(HeapRegion* r) { 3035 if (!r->is_continues_humongous()) { 3036 bool failures = false; 3037 r->verify(_vo, &failures); 3038 if (failures) { 3039 _failures = true; 3040 } else { 3041 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo); 3042 r->object_iterate(¬_dead_yet_cl); 3043 if (_vo != VerifyOption_G1UseNextMarking) { 3044 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) { 3045 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] " 3046 "max_live_bytes "SIZE_FORMAT" " 3047 "< calculated "SIZE_FORMAT, 3048 r->bottom(), r->end(), 3049 r->max_live_bytes(), 3050 not_dead_yet_cl.live_bytes()); 3051 _failures = true; 3052 } 3053 } else { 3054 // When vo == UseNextMarking we cannot currently do a sanity 3055 // check on the live bytes as the calculation has not been 3056 // finalized yet. 3057 } 3058 } 3059 } 3060 return false; // stop the region iteration if we hit a failure 3061 } 3062 }; 3063 3064 // This is the task used for parallel verification of the heap regions 3065 3066 class G1ParVerifyTask: public AbstractGangTask { 3067 private: 3068 G1CollectedHeap* _g1h; 3069 VerifyOption _vo; 3070 bool _failures; 3071 HeapRegionClaimer _hrclaimer; 3072 3073 public: 3074 // _vo == UsePrevMarking -> use "prev" marking information, 3075 // _vo == UseNextMarking -> use "next" marking information, 3076 // _vo == UseMarkWord -> use mark word from object header. 3077 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) : 3078 AbstractGangTask("Parallel verify task"), 3079 _g1h(g1h), 3080 _vo(vo), 3081 _failures(false), 3082 _hrclaimer(g1h->workers()->active_workers()) {} 3083 3084 bool failures() { 3085 return _failures; 3086 } 3087 3088 void work(uint worker_id) { 3089 HandleMark hm; 3090 VerifyRegionClosure blk(true, _vo); 3091 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer); 3092 if (blk.failures()) { 3093 _failures = true; 3094 } 3095 } 3096 }; 3097 3098 void G1CollectedHeap::verify(bool silent, VerifyOption vo) { 3099 if (SafepointSynchronize::is_at_safepoint()) { 3100 assert(Thread::current()->is_VM_thread(), 3101 "Expected to be executed serially by the VM thread at this point"); 3102 3103 if (!silent) { gclog_or_tty->print("Roots "); } 3104 VerifyRootsClosure rootsCl(vo); 3105 VerifyKlassClosure klassCl(this, &rootsCl); 3106 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false); 3107 3108 // We apply the relevant closures to all the oops in the 3109 // system dictionary, class loader data graph, the string table 3110 // and the nmethods in the code cache. 3111 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo); 3112 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl); 3113 3114 process_all_roots(true, // activate StrongRootsScope 3115 SO_AllCodeCache, // roots scanning options 3116 &rootsCl, 3117 &cldCl, 3118 &blobsCl); 3119 3120 bool failures = rootsCl.failures() || codeRootsCl.failures(); 3121 3122 if (vo != VerifyOption_G1UseMarkWord) { 3123 // If we're verifying during a full GC then the region sets 3124 // will have been torn down at the start of the GC. Therefore 3125 // verifying the region sets will fail. So we only verify 3126 // the region sets when not in a full GC. 3127 if (!silent) { gclog_or_tty->print("HeapRegionSets "); } 3128 verify_region_sets(); 3129 } 3130 3131 if (!silent) { gclog_or_tty->print("HeapRegions "); } 3132 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) { 3133 3134 G1ParVerifyTask task(this, vo); 3135 assert(UseDynamicNumberOfGCThreads || 3136 workers()->active_workers() == workers()->total_workers(), 3137 "If not dynamic should be using all the workers"); 3138 int n_workers = workers()->active_workers(); 3139 set_par_threads(n_workers); 3140 workers()->run_task(&task); 3141 set_par_threads(0); 3142 if (task.failures()) { 3143 failures = true; 3144 } 3145 3146 } else { 3147 VerifyRegionClosure blk(false, vo); 3148 heap_region_iterate(&blk); 3149 if (blk.failures()) { 3150 failures = true; 3151 } 3152 } 3153 3154 if (G1StringDedup::is_enabled()) { 3155 if (!silent) gclog_or_tty->print("StrDedup "); 3156 G1StringDedup::verify(); 3157 } 3158 3159 if (failures) { 3160 gclog_or_tty->print_cr("Heap:"); 3161 // It helps to have the per-region information in the output to 3162 // help us track down what went wrong. This is why we call 3163 // print_extended_on() instead of print_on(). 3164 print_extended_on(gclog_or_tty); 3165 gclog_or_tty->cr(); 3166 #ifndef PRODUCT 3167 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) { 3168 concurrent_mark()->print_reachable("at-verification-failure", 3169 vo, false /* all */); 3170 } 3171 #endif 3172 gclog_or_tty->flush(); 3173 } 3174 guarantee(!failures, "there should not have been any failures"); 3175 } else { 3176 if (!silent) { 3177 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet"); 3178 if (G1StringDedup::is_enabled()) { 3179 gclog_or_tty->print(", StrDedup"); 3180 } 3181 gclog_or_tty->print(") "); 3182 } 3183 } 3184 } 3185 3186 void G1CollectedHeap::verify(bool silent) { 3187 verify(silent, VerifyOption_G1UsePrevMarking); 3188 } 3189 3190 double G1CollectedHeap::verify(bool guard, const char* msg) { 3191 double verify_time_ms = 0.0; 3192 3193 if (guard && total_collections() >= VerifyGCStartAt) { 3194 double verify_start = os::elapsedTime(); 3195 HandleMark hm; // Discard invalid handles created during verification 3196 prepare_for_verify(); 3197 Universe::verify(VerifyOption_G1UsePrevMarking, msg); 3198 verify_time_ms = (os::elapsedTime() - verify_start) * 1000; 3199 } 3200 3201 return verify_time_ms; 3202 } 3203 3204 void G1CollectedHeap::verify_before_gc() { 3205 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:"); 3206 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms); 3207 } 3208 3209 void G1CollectedHeap::verify_after_gc() { 3210 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:"); 3211 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms); 3212 } 3213 3214 class PrintRegionClosure: public HeapRegionClosure { 3215 outputStream* _st; 3216 public: 3217 PrintRegionClosure(outputStream* st) : _st(st) {} 3218 bool doHeapRegion(HeapRegion* r) { 3219 r->print_on(_st); 3220 return false; 3221 } 3222 }; 3223 3224 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 3225 const HeapRegion* hr, 3226 const VerifyOption vo) const { 3227 switch (vo) { 3228 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); 3229 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); 3230 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked(); 3231 default: ShouldNotReachHere(); 3232 } 3233 return false; // keep some compilers happy 3234 } 3235 3236 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 3237 const VerifyOption vo) const { 3238 switch (vo) { 3239 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); 3240 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); 3241 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked(); 3242 default: ShouldNotReachHere(); 3243 } 3244 return false; // keep some compilers happy 3245 } 3246 3247 void G1CollectedHeap::print_on(outputStream* st) const { 3248 st->print(" %-20s", "garbage-first heap"); 3249 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 3250 capacity()/K, used_unlocked()/K); 3251 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")", 3252 _hrm.reserved().start(), 3253 _hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords, 3254 _hrm.reserved().end()); 3255 st->cr(); 3256 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); 3257 uint young_regions = _young_list->length(); 3258 st->print("%u young (" SIZE_FORMAT "K), ", young_regions, 3259 (size_t) young_regions * HeapRegion::GrainBytes / K); 3260 uint survivor_regions = g1_policy()->recorded_survivor_regions(); 3261 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, 3262 (size_t) survivor_regions * HeapRegion::GrainBytes / K); 3263 st->cr(); 3264 MetaspaceAux::print_on(st); 3265 } 3266 3267 void G1CollectedHeap::print_extended_on(outputStream* st) const { 3268 print_on(st); 3269 3270 // Print the per-region information. 3271 st->cr(); 3272 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), " 3273 "HS=humongous(starts), HC=humongous(continues), " 3274 "CS=collection set, F=free, TS=gc time stamp, " 3275 "PTAMS=previous top-at-mark-start, " 3276 "NTAMS=next top-at-mark-start)"); 3277 PrintRegionClosure blk(st); 3278 heap_region_iterate(&blk); 3279 } 3280 3281 void G1CollectedHeap::print_on_error(outputStream* st) const { 3282 this->CollectedHeap::print_on_error(st); 3283 3284 if (_cm != NULL) { 3285 st->cr(); 3286 _cm->print_on_error(st); 3287 } 3288 } 3289 3290 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const { 3291 workers()->print_worker_threads_on(st); 3292 _cmThread->print_on(st); 3293 st->cr(); 3294 _cm->print_worker_threads_on(st); 3295 _cg1r->print_worker_threads_on(st); 3296 if (G1StringDedup::is_enabled()) { 3297 G1StringDedup::print_worker_threads_on(st); 3298 } 3299 } 3300 3301 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { 3302 workers()->threads_do(tc); 3303 tc->do_thread(_cmThread); 3304 _cg1r->threads_do(tc); 3305 if (G1StringDedup::is_enabled()) { 3306 G1StringDedup::threads_do(tc); 3307 } 3308 } 3309 3310 void G1CollectedHeap::print_tracing_info() const { 3311 // We'll overload this to mean "trace GC pause statistics." 3312 if (TraceYoungGenTime || TraceOldGenTime) { 3313 // The "G1CollectorPolicy" is keeping track of these stats, so delegate 3314 // to that. 3315 g1_policy()->print_tracing_info(); 3316 } 3317 if (G1SummarizeRSetStats) { 3318 g1_rem_set()->print_summary_info(); 3319 } 3320 if (G1SummarizeConcMark) { 3321 concurrent_mark()->print_summary_info(); 3322 } 3323 g1_policy()->print_yg_surv_rate_info(); 3324 SpecializationStats::print(); 3325 } 3326 3327 #ifndef PRODUCT 3328 // Helpful for debugging RSet issues. 3329 3330 class PrintRSetsClosure : public HeapRegionClosure { 3331 private: 3332 const char* _msg; 3333 size_t _occupied_sum; 3334 3335 public: 3336 bool doHeapRegion(HeapRegion* r) { 3337 HeapRegionRemSet* hrrs = r->rem_set(); 3338 size_t occupied = hrrs->occupied(); 3339 _occupied_sum += occupied; 3340 3341 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT, 3342 HR_FORMAT_PARAMS(r)); 3343 if (occupied == 0) { 3344 gclog_or_tty->print_cr(" RSet is empty"); 3345 } else { 3346 hrrs->print(); 3347 } 3348 gclog_or_tty->print_cr("----------"); 3349 return false; 3350 } 3351 3352 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { 3353 gclog_or_tty->cr(); 3354 gclog_or_tty->print_cr("========================================"); 3355 gclog_or_tty->print_cr("%s", msg); 3356 gclog_or_tty->cr(); 3357 } 3358 3359 ~PrintRSetsClosure() { 3360 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum); 3361 gclog_or_tty->print_cr("========================================"); 3362 gclog_or_tty->cr(); 3363 } 3364 }; 3365 3366 void G1CollectedHeap::print_cset_rsets() { 3367 PrintRSetsClosure cl("Printing CSet RSets"); 3368 collection_set_iterate(&cl); 3369 } 3370 3371 void G1CollectedHeap::print_all_rsets() { 3372 PrintRSetsClosure cl("Printing All RSets");; 3373 heap_region_iterate(&cl); 3374 } 3375 #endif // PRODUCT 3376 3377 G1CollectedHeap* G1CollectedHeap::heap() { 3378 assert(_sh->kind() == CollectedHeap::G1CollectedHeap, 3379 "not a garbage-first heap"); 3380 return _g1h; 3381 } 3382 3383 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) { 3384 // always_do_update_barrier = false; 3385 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 3386 // Fill TLAB's and such 3387 accumulate_statistics_all_tlabs(); 3388 ensure_parsability(true); 3389 3390 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) && 3391 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) { 3392 g1_rem_set()->print_periodic_summary_info("Before GC RS summary"); 3393 } 3394 } 3395 3396 void G1CollectedHeap::gc_epilogue(bool full) { 3397 3398 if (G1SummarizeRSetStats && 3399 (G1SummarizeRSetStatsPeriod > 0) && 3400 // we are at the end of the GC. Total collections has already been increased. 3401 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) { 3402 g1_rem_set()->print_periodic_summary_info("After GC RS summary"); 3403 } 3404 3405 // FIXME: what is this about? 3406 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" 3407 // is set. 3408 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(), 3409 "derived pointer present")); 3410 // always_do_update_barrier = true; 3411 3412 resize_all_tlabs(); 3413 allocation_context_stats().update(full); 3414 3415 // We have just completed a GC. Update the soft reference 3416 // policy with the new heap occupancy 3417 Universe::update_heap_info_at_gc(); 3418 } 3419 3420 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, 3421 unsigned int gc_count_before, 3422 bool* succeeded, 3423 GCCause::Cause gc_cause) { 3424 assert_heap_not_locked_and_not_at_safepoint(); 3425 g1_policy()->record_stop_world_start(); 3426 VM_G1IncCollectionPause op(gc_count_before, 3427 word_size, 3428 false, /* should_initiate_conc_mark */ 3429 g1_policy()->max_pause_time_ms(), 3430 gc_cause); 3431 3432 op.set_allocation_context(AllocationContext::current()); 3433 VMThread::execute(&op); 3434 3435 HeapWord* result = op.result(); 3436 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded(); 3437 assert(result == NULL || ret_succeeded, 3438 "the result should be NULL if the VM did not succeed"); 3439 *succeeded = ret_succeeded; 3440 3441 assert_heap_not_locked(); 3442 return result; 3443 } 3444 3445 void 3446 G1CollectedHeap::doConcurrentMark() { 3447 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); 3448 if (!_cmThread->in_progress()) { 3449 _cmThread->set_started(); 3450 CGC_lock->notify(); 3451 } 3452 } 3453 3454 size_t G1CollectedHeap::pending_card_num() { 3455 size_t extra_cards = 0; 3456 JavaThread *curr = Threads::first(); 3457 while (curr != NULL) { 3458 DirtyCardQueue& dcq = curr->dirty_card_queue(); 3459 extra_cards += dcq.size(); 3460 curr = curr->next(); 3461 } 3462 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 3463 size_t buffer_size = dcqs.buffer_size(); 3464 size_t buffer_num = dcqs.completed_buffers_num(); 3465 3466 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes 3467 // in bytes - not the number of 'entries'. We need to convert 3468 // into a number of cards. 3469 return (buffer_size * buffer_num + extra_cards) / oopSize; 3470 } 3471 3472 size_t G1CollectedHeap::cards_scanned() { 3473 return g1_rem_set()->cardsScanned(); 3474 } 3475 3476 bool G1CollectedHeap::humongous_region_is_always_live(uint index) { 3477 HeapRegion* region = region_at(index); 3478 assert(region->is_starts_humongous(), "Must start a humongous object"); 3479 return oop(region->bottom())->is_objArray() || !region->rem_set()->is_empty(); 3480 } 3481 3482 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure { 3483 private: 3484 size_t _total_humongous; 3485 size_t _candidate_humongous; 3486 3487 DirtyCardQueue _dcq; 3488 3489 bool humongous_region_is_candidate(uint index) { 3490 HeapRegion* region = G1CollectedHeap::heap()->region_at(index); 3491 assert(region->is_starts_humongous(), "Must start a humongous object"); 3492 HeapRegionRemSet* const rset = region->rem_set(); 3493 bool const allow_stale_refs = G1EagerReclaimHumongousObjectsWithStaleRefs; 3494 return !oop(region->bottom())->is_objArray() && 3495 ((allow_stale_refs && rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)) || 3496 (!allow_stale_refs && rset->is_empty())); 3497 } 3498 3499 public: 3500 RegisterHumongousWithInCSetFastTestClosure() 3501 : _total_humongous(0), 3502 _candidate_humongous(0), 3503 _dcq(&JavaThread::dirty_card_queue_set()) { 3504 } 3505 3506 virtual bool doHeapRegion(HeapRegion* r) { 3507 if (!r->is_starts_humongous()) { 3508 return false; 3509 } 3510 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 3511 3512 uint region_idx = r->hrm_index(); 3513 bool is_candidate = humongous_region_is_candidate(region_idx); 3514 // Is_candidate already filters out humongous object with large remembered sets. 3515 // If we have a humongous object with a few remembered sets, we simply flush these 3516 // remembered set entries into the DCQS. That will result in automatic 3517 // re-evaluation of their remembered set entries during the following evacuation 3518 // phase. 3519 if (is_candidate) { 3520 if (!r->rem_set()->is_empty()) { 3521 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries), 3522 "Found a not-small remembered set here. This is inconsistent with previous assumptions."); 3523 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set(); 3524 HeapRegionRemSetIterator hrrs(r->rem_set()); 3525 size_t card_index; 3526 while (hrrs.has_next(card_index)) { 3527 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index); 3528 // Only process valid cards. 3529 if (!g1h->heap_region_containing(bs->addr_for(card_ptr))->is_free()) { 3530 if (*card_ptr != CardTableModRefBS::dirty_card_val()) { 3531 *card_ptr = CardTableModRefBS::dirty_card_val(); 3532 _dcq.enqueue(card_ptr); 3533 } 3534 } 3535 } 3536 r->rem_set()->clear_locked(); 3537 } 3538 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty."); 3539 g1h->register_humongous_region_with_in_cset_fast_test(region_idx); 3540 _candidate_humongous++; 3541 } 3542 _total_humongous++; 3543 3544 return false; 3545 } 3546 3547 size_t total_humongous() const { return _total_humongous; } 3548 size_t candidate_humongous() const { return _candidate_humongous; } 3549 3550 void flush_rem_set_entries() { _dcq.flush(); } 3551 }; 3552 3553 void G1CollectedHeap::register_humongous_regions_with_in_cset_fast_test() { 3554 if (!G1EagerReclaimHumongousObjects) { 3555 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0); 3556 return; 3557 } 3558 double time = os::elapsed_counter(); 3559 3560 RegisterHumongousWithInCSetFastTestClosure cl; 3561 heap_region_iterate(&cl); 3562 3563 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0; 3564 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time, 3565 cl.total_humongous(), 3566 cl.candidate_humongous()); 3567 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0; 3568 3569 if (_has_humongous_reclaim_candidates || G1TraceEagerReclaimHumongousObjects) { 3570 clear_humongous_is_live_table(); 3571 } 3572 3573 // Finally flush all remembered set entries to re-check into the global DCQS. 3574 cl.flush_rem_set_entries(); 3575 } 3576 3577 void 3578 G1CollectedHeap::setup_surviving_young_words() { 3579 assert(_surviving_young_words == NULL, "pre-condition"); 3580 uint array_length = g1_policy()->young_cset_region_length(); 3581 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC); 3582 if (_surviving_young_words == NULL) { 3583 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR, 3584 "Not enough space for young surv words summary."); 3585 } 3586 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t)); 3587 #ifdef ASSERT 3588 for (uint i = 0; i < array_length; ++i) { 3589 assert( _surviving_young_words[i] == 0, "memset above" ); 3590 } 3591 #endif // !ASSERT 3592 } 3593 3594 void 3595 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) { 3596 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); 3597 uint array_length = g1_policy()->young_cset_region_length(); 3598 for (uint i = 0; i < array_length; ++i) { 3599 _surviving_young_words[i] += surv_young_words[i]; 3600 } 3601 } 3602 3603 void 3604 G1CollectedHeap::cleanup_surviving_young_words() { 3605 guarantee( _surviving_young_words != NULL, "pre-condition" ); 3606 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words); 3607 _surviving_young_words = NULL; 3608 } 3609 3610 #ifdef ASSERT 3611 class VerifyCSetClosure: public HeapRegionClosure { 3612 public: 3613 bool doHeapRegion(HeapRegion* hr) { 3614 // Here we check that the CSet region's RSet is ready for parallel 3615 // iteration. The fields that we'll verify are only manipulated 3616 // when the region is part of a CSet and is collected. Afterwards, 3617 // we reset these fields when we clear the region's RSet (when the 3618 // region is freed) so they are ready when the region is 3619 // re-allocated. The only exception to this is if there's an 3620 // evacuation failure and instead of freeing the region we leave 3621 // it in the heap. In that case, we reset these fields during 3622 // evacuation failure handling. 3623 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification"); 3624 3625 // Here's a good place to add any other checks we'd like to 3626 // perform on CSet regions. 3627 return false; 3628 } 3629 }; 3630 #endif // ASSERT 3631 3632 #if TASKQUEUE_STATS 3633 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) { 3634 st->print_raw_cr("GC Task Stats"); 3635 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); 3636 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); 3637 } 3638 3639 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const { 3640 print_taskqueue_stats_hdr(st); 3641 3642 TaskQueueStats totals; 3643 const int n = workers()->total_workers(); 3644 for (int i = 0; i < n; ++i) { 3645 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr(); 3646 totals += task_queue(i)->stats; 3647 } 3648 st->print_raw("tot "); totals.print(st); st->cr(); 3649 3650 DEBUG_ONLY(totals.verify()); 3651 } 3652 3653 void G1CollectedHeap::reset_taskqueue_stats() { 3654 const int n = workers()->total_workers(); 3655 for (int i = 0; i < n; ++i) { 3656 task_queue(i)->stats.reset(); 3657 } 3658 } 3659 #endif // TASKQUEUE_STATS 3660 3661 void G1CollectedHeap::log_gc_header() { 3662 if (!G1Log::fine()) { 3663 return; 3664 } 3665 3666 gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id()); 3667 3668 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause()) 3669 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)") 3670 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : ""); 3671 3672 gclog_or_tty->print("[%s", (const char*)gc_cause_str); 3673 } 3674 3675 void G1CollectedHeap::log_gc_footer(double pause_time_sec) { 3676 if (!G1Log::fine()) { 3677 return; 3678 } 3679 3680 if (G1Log::finer()) { 3681 if (evacuation_failed()) { 3682 gclog_or_tty->print(" (to-space exhausted)"); 3683 } 3684 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec); 3685 g1_policy()->phase_times()->note_gc_end(); 3686 g1_policy()->phase_times()->print(pause_time_sec); 3687 g1_policy()->print_detailed_heap_transition(); 3688 } else { 3689 if (evacuation_failed()) { 3690 gclog_or_tty->print("--"); 3691 } 3692 g1_policy()->print_heap_transition(); 3693 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec); 3694 } 3695 gclog_or_tty->flush(); 3696 } 3697 3698 bool 3699 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { 3700 assert_at_safepoint(true /* should_be_vm_thread */); 3701 guarantee(!is_gc_active(), "collection is not reentrant"); 3702 3703 if (GC_locker::check_active_before_gc()) { 3704 return false; 3705 } 3706 3707 _gc_timer_stw->register_gc_start(); 3708 3709 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start()); 3710 3711 SvcGCMarker sgcm(SvcGCMarker::MINOR); 3712 ResourceMark rm; 3713 3714 print_heap_before_gc(); 3715 trace_heap_before_gc(_gc_tracer_stw); 3716 3717 verify_region_sets_optional(); 3718 verify_dirty_young_regions(); 3719 3720 // This call will decide whether this pause is an initial-mark 3721 // pause. If it is, during_initial_mark_pause() will return true 3722 // for the duration of this pause. 3723 g1_policy()->decide_on_conc_mark_initiation(); 3724 3725 // We do not allow initial-mark to be piggy-backed on a mixed GC. 3726 assert(!g1_policy()->during_initial_mark_pause() || 3727 g1_policy()->gcs_are_young(), "sanity"); 3728 3729 // We also do not allow mixed GCs during marking. 3730 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity"); 3731 3732 // Record whether this pause is an initial mark. When the current 3733 // thread has completed its logging output and it's safe to signal 3734 // the CM thread, the flag's value in the policy has been reset. 3735 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause(); 3736 3737 // Inner scope for scope based logging, timers, and stats collection 3738 { 3739 EvacuationInfo evacuation_info; 3740 3741 if (g1_policy()->during_initial_mark_pause()) { 3742 // We are about to start a marking cycle, so we increment the 3743 // full collection counter. 3744 increment_old_marking_cycles_started(); 3745 register_concurrent_cycle_start(_gc_timer_stw->gc_start()); 3746 } 3747 3748 _gc_tracer_stw->report_yc_type(yc_type()); 3749 3750 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty); 3751 3752 int active_workers = workers()->active_workers(); 3753 double pause_start_sec = os::elapsedTime(); 3754 g1_policy()->phase_times()->note_gc_start(active_workers); 3755 log_gc_header(); 3756 3757 TraceCollectorStats tcs(g1mm()->incremental_collection_counters()); 3758 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause()); 3759 3760 // If the secondary_free_list is not empty, append it to the 3761 // free_list. No need to wait for the cleanup operation to finish; 3762 // the region allocation code will check the secondary_free_list 3763 // and wait if necessary. If the G1StressConcRegionFreeing flag is 3764 // set, skip this step so that the region allocation code has to 3765 // get entries from the secondary_free_list. 3766 if (!G1StressConcRegionFreeing) { 3767 append_secondary_free_list_if_not_empty_with_lock(); 3768 } 3769 3770 assert(check_young_list_well_formed(), "young list should be well formed"); 3771 3772 // Don't dynamically change the number of GC threads this early. A value of 3773 // 0 is used to indicate serial work. When parallel work is done, 3774 // it will be set. 3775 3776 { // Call to jvmpi::post_class_unload_events must occur outside of active GC 3777 IsGCActiveMark x; 3778 3779 gc_prologue(false); 3780 increment_total_collections(false /* full gc */); 3781 increment_gc_time_stamp(); 3782 3783 verify_before_gc(); 3784 3785 check_bitmaps("GC Start"); 3786 3787 COMPILER2_PRESENT(DerivedPointerTable::clear()); 3788 3789 // Please see comment in g1CollectedHeap.hpp and 3790 // G1CollectedHeap::ref_processing_init() to see how 3791 // reference processing currently works in G1. 3792 3793 // Enable discovery in the STW reference processor 3794 ref_processor_stw()->enable_discovery(); 3795 3796 { 3797 // We want to temporarily turn off discovery by the 3798 // CM ref processor, if necessary, and turn it back on 3799 // on again later if we do. Using a scoped 3800 // NoRefDiscovery object will do this. 3801 NoRefDiscovery no_cm_discovery(ref_processor_cm()); 3802 3803 // Forget the current alloc region (we might even choose it to be part 3804 // of the collection set!). 3805 _allocator->release_mutator_alloc_region(); 3806 3807 // We should call this after we retire the mutator alloc 3808 // region(s) so that all the ALLOC / RETIRE events are generated 3809 // before the start GC event. 3810 _hr_printer.start_gc(false /* full */, (size_t) total_collections()); 3811 3812 // This timing is only used by the ergonomics to handle our pause target. 3813 // It is unclear why this should not include the full pause. We will 3814 // investigate this in CR 7178365. 3815 // 3816 // Preserving the old comment here if that helps the investigation: 3817 // 3818 // The elapsed time induced by the start time below deliberately elides 3819 // the possible verification above. 3820 double sample_start_time_sec = os::elapsedTime(); 3821 3822 #if YOUNG_LIST_VERBOSE 3823 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:"); 3824 _young_list->print(); 3825 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 3826 #endif // YOUNG_LIST_VERBOSE 3827 3828 g1_policy()->record_collection_pause_start(sample_start_time_sec); 3829 3830 double scan_wait_start = os::elapsedTime(); 3831 // We have to wait until the CM threads finish scanning the 3832 // root regions as it's the only way to ensure that all the 3833 // objects on them have been correctly scanned before we start 3834 // moving them during the GC. 3835 bool waited = _cm->root_regions()->wait_until_scan_finished(); 3836 double wait_time_ms = 0.0; 3837 if (waited) { 3838 double scan_wait_end = os::elapsedTime(); 3839 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0; 3840 } 3841 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms); 3842 3843 #if YOUNG_LIST_VERBOSE 3844 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:"); 3845 _young_list->print(); 3846 #endif // YOUNG_LIST_VERBOSE 3847 3848 if (g1_policy()->during_initial_mark_pause()) { 3849 concurrent_mark()->checkpointRootsInitialPre(); 3850 } 3851 3852 #if YOUNG_LIST_VERBOSE 3853 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:"); 3854 _young_list->print(); 3855 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 3856 #endif // YOUNG_LIST_VERBOSE 3857 3858 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info); 3859 3860 register_humongous_regions_with_in_cset_fast_test(); 3861 3862 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table."); 3863 3864 _cm->note_start_of_gc(); 3865 // We should not verify the per-thread SATB buffers given that 3866 // we have not filtered them yet (we'll do so during the 3867 // GC). We also call this after finalize_cset() to 3868 // ensure that the CSet has been finalized. 3869 _cm->verify_no_cset_oops(true /* verify_stacks */, 3870 true /* verify_enqueued_buffers */, 3871 false /* verify_thread_buffers */, 3872 true /* verify_fingers */); 3873 3874 if (_hr_printer.is_active()) { 3875 HeapRegion* hr = g1_policy()->collection_set(); 3876 while (hr != NULL) { 3877 _hr_printer.cset(hr); 3878 hr = hr->next_in_collection_set(); 3879 } 3880 } 3881 3882 #ifdef ASSERT 3883 VerifyCSetClosure cl; 3884 collection_set_iterate(&cl); 3885 #endif // ASSERT 3886 3887 setup_surviving_young_words(); 3888 3889 // Initialize the GC alloc regions. 3890 _allocator->init_gc_alloc_regions(evacuation_info); 3891 3892 // Actually do the work... 3893 evacuate_collection_set(evacuation_info); 3894 3895 // We do this to mainly verify the per-thread SATB buffers 3896 // (which have been filtered by now) since we didn't verify 3897 // them earlier. No point in re-checking the stacks / enqueued 3898 // buffers given that the CSet has not changed since last time 3899 // we checked. 3900 _cm->verify_no_cset_oops(false /* verify_stacks */, 3901 false /* verify_enqueued_buffers */, 3902 true /* verify_thread_buffers */, 3903 true /* verify_fingers */); 3904 3905 free_collection_set(g1_policy()->collection_set(), evacuation_info); 3906 3907 eagerly_reclaim_humongous_regions(); 3908 3909 g1_policy()->clear_collection_set(); 3910 3911 cleanup_surviving_young_words(); 3912 3913 // Start a new incremental collection set for the next pause. 3914 g1_policy()->start_incremental_cset_building(); 3915 3916 clear_cset_fast_test(); 3917 3918 _young_list->reset_sampled_info(); 3919 3920 // Don't check the whole heap at this point as the 3921 // GC alloc regions from this pause have been tagged 3922 // as survivors and moved on to the survivor list. 3923 // Survivor regions will fail the !is_young() check. 3924 assert(check_young_list_empty(false /* check_heap */), 3925 "young list should be empty"); 3926 3927 #if YOUNG_LIST_VERBOSE 3928 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:"); 3929 _young_list->print(); 3930 #endif // YOUNG_LIST_VERBOSE 3931 3932 g1_policy()->record_survivor_regions(_young_list->survivor_length(), 3933 _young_list->first_survivor_region(), 3934 _young_list->last_survivor_region()); 3935 3936 _young_list->reset_auxilary_lists(); 3937 3938 if (evacuation_failed()) { 3939 _allocator->set_used(recalculate_used()); 3940 uint n_queues = MAX2((int)ParallelGCThreads, 1); 3941 for (uint i = 0; i < n_queues; i++) { 3942 if (_evacuation_failed_info_array[i].has_failed()) { 3943 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]); 3944 } 3945 } 3946 } else { 3947 // The "used" of the the collection set have already been subtracted 3948 // when they were freed. Add in the bytes evacuated. 3949 _allocator->increase_used(g1_policy()->bytes_copied_during_gc()); 3950 } 3951 3952 if (g1_policy()->during_initial_mark_pause()) { 3953 // We have to do this before we notify the CM threads that 3954 // they can start working to make sure that all the 3955 // appropriate initialization is done on the CM object. 3956 concurrent_mark()->checkpointRootsInitialPost(); 3957 set_marking_started(); 3958 // Note that we don't actually trigger the CM thread at 3959 // this point. We do that later when we're sure that 3960 // the current thread has completed its logging output. 3961 } 3962 3963 allocate_dummy_regions(); 3964 3965 #if YOUNG_LIST_VERBOSE 3966 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:"); 3967 _young_list->print(); 3968 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 3969 #endif // YOUNG_LIST_VERBOSE 3970 3971 _allocator->init_mutator_alloc_region(); 3972 3973 { 3974 size_t expand_bytes = g1_policy()->expansion_amount(); 3975 if (expand_bytes > 0) { 3976 size_t bytes_before = capacity(); 3977 // No need for an ergo verbose message here, 3978 // expansion_amount() does this when it returns a value > 0. 3979 if (!expand(expand_bytes)) { 3980 // We failed to expand the heap. Cannot do anything about it. 3981 } 3982 } 3983 } 3984 3985 // We redo the verification but now wrt to the new CSet which 3986 // has just got initialized after the previous CSet was freed. 3987 _cm->verify_no_cset_oops(true /* verify_stacks */, 3988 true /* verify_enqueued_buffers */, 3989 true /* verify_thread_buffers */, 3990 true /* verify_fingers */); 3991 _cm->note_end_of_gc(); 3992 3993 // This timing is only used by the ergonomics to handle our pause target. 3994 // It is unclear why this should not include the full pause. We will 3995 // investigate this in CR 7178365. 3996 double sample_end_time_sec = os::elapsedTime(); 3997 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; 3998 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info); 3999 4000 MemoryService::track_memory_usage(); 4001 4002 // In prepare_for_verify() below we'll need to scan the deferred 4003 // update buffers to bring the RSets up-to-date if 4004 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning 4005 // the update buffers we'll probably need to scan cards on the 4006 // regions we just allocated to (i.e., the GC alloc 4007 // regions). However, during the last GC we called 4008 // set_saved_mark() on all the GC alloc regions, so card 4009 // scanning might skip the [saved_mark_word()...top()] area of 4010 // those regions (i.e., the area we allocated objects into 4011 // during the last GC). But it shouldn't. Given that 4012 // saved_mark_word() is conditional on whether the GC time stamp 4013 // on the region is current or not, by incrementing the GC time 4014 // stamp here we invalidate all the GC time stamps on all the 4015 // regions and saved_mark_word() will simply return top() for 4016 // all the regions. This is a nicer way of ensuring this rather 4017 // than iterating over the regions and fixing them. In fact, the 4018 // GC time stamp increment here also ensures that 4019 // saved_mark_word() will return top() between pauses, i.e., 4020 // during concurrent refinement. So we don't need the 4021 // is_gc_active() check to decided which top to use when 4022 // scanning cards (see CR 7039627). 4023 increment_gc_time_stamp(); 4024 4025 verify_after_gc(); 4026 check_bitmaps("GC End"); 4027 4028 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 4029 ref_processor_stw()->verify_no_references_recorded(); 4030 4031 // CM reference discovery will be re-enabled if necessary. 4032 } 4033 4034 // We should do this after we potentially expand the heap so 4035 // that all the COMMIT events are generated before the end GC 4036 // event, and after we retire the GC alloc regions so that all 4037 // RETIRE events are generated before the end GC event. 4038 _hr_printer.end_gc(false /* full */, (size_t) total_collections()); 4039 4040 #ifdef TRACESPINNING 4041 ParallelTaskTerminator::print_termination_counts(); 4042 #endif 4043 4044 gc_epilogue(false); 4045 } 4046 4047 // Print the remainder of the GC log output. 4048 log_gc_footer(os::elapsedTime() - pause_start_sec); 4049 4050 // It is not yet to safe to tell the concurrent mark to 4051 // start as we have some optional output below. We don't want the 4052 // output from the concurrent mark thread interfering with this 4053 // logging output either. 4054 4055 _hrm.verify_optional(); 4056 verify_region_sets_optional(); 4057 4058 TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats()); 4059 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); 4060 4061 print_heap_after_gc(); 4062 trace_heap_after_gc(_gc_tracer_stw); 4063 4064 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 4065 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 4066 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 4067 // before any GC notifications are raised. 4068 g1mm()->update_sizes(); 4069 4070 _gc_tracer_stw->report_evacuation_info(&evacuation_info); 4071 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold()); 4072 _gc_timer_stw->register_gc_end(); 4073 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions()); 4074 } 4075 // It should now be safe to tell the concurrent mark thread to start 4076 // without its logging output interfering with the logging output 4077 // that came from the pause. 4078 4079 if (should_start_conc_mark) { 4080 // CAUTION: after the doConcurrentMark() call below, 4081 // the concurrent marking thread(s) could be running 4082 // concurrently with us. Make sure that anything after 4083 // this point does not assume that we are the only GC thread 4084 // running. Note: of course, the actual marking work will 4085 // not start until the safepoint itself is released in 4086 // SuspendibleThreadSet::desynchronize(). 4087 doConcurrentMark(); 4088 } 4089 4090 return true; 4091 } 4092 4093 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) { 4094 _drain_in_progress = false; 4095 set_evac_failure_closure(cl); 4096 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true); 4097 } 4098 4099 void G1CollectedHeap::finalize_for_evac_failure() { 4100 assert(_evac_failure_scan_stack != NULL && 4101 _evac_failure_scan_stack->length() == 0, 4102 "Postcondition"); 4103 assert(!_drain_in_progress, "Postcondition"); 4104 delete _evac_failure_scan_stack; 4105 _evac_failure_scan_stack = NULL; 4106 } 4107 4108 void G1CollectedHeap::remove_self_forwarding_pointers() { 4109 double remove_self_forwards_start = os::elapsedTime(); 4110 4111 set_par_threads(); 4112 G1ParRemoveSelfForwardPtrsTask rsfp_task(this); 4113 workers()->run_task(&rsfp_task); 4114 set_par_threads(0); 4115 4116 // Now restore saved marks, if any. 4117 assert(_objs_with_preserved_marks.size() == 4118 _preserved_marks_of_objs.size(), "Both or none."); 4119 while (!_objs_with_preserved_marks.is_empty()) { 4120 oop obj = _objs_with_preserved_marks.pop(); 4121 markOop m = _preserved_marks_of_objs.pop(); 4122 obj->set_mark(m); 4123 } 4124 _objs_with_preserved_marks.clear(true); 4125 _preserved_marks_of_objs.clear(true); 4126 4127 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0); 4128 } 4129 4130 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) { 4131 _evac_failure_scan_stack->push(obj); 4132 } 4133 4134 void G1CollectedHeap::drain_evac_failure_scan_stack() { 4135 assert(_evac_failure_scan_stack != NULL, "precondition"); 4136 4137 while (_evac_failure_scan_stack->length() > 0) { 4138 oop obj = _evac_failure_scan_stack->pop(); 4139 _evac_failure_closure->set_region(heap_region_containing(obj)); 4140 obj->oop_iterate_backwards(_evac_failure_closure); 4141 } 4142 } 4143 4144 oop 4145 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state, 4146 oop old) { 4147 assert(obj_in_cs(old), 4148 err_msg("obj: "PTR_FORMAT" should still be in the CSet", 4149 (HeapWord*) old)); 4150 markOop m = old->mark(); 4151 oop forward_ptr = old->forward_to_atomic(old); 4152 if (forward_ptr == NULL) { 4153 // Forward-to-self succeeded. 4154 assert(_par_scan_state != NULL, "par scan state"); 4155 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure(); 4156 uint queue_num = _par_scan_state->queue_num(); 4157 4158 _evacuation_failed = true; 4159 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size()); 4160 if (_evac_failure_closure != cl) { 4161 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag); 4162 assert(!_drain_in_progress, 4163 "Should only be true while someone holds the lock."); 4164 // Set the global evac-failure closure to the current thread's. 4165 assert(_evac_failure_closure == NULL, "Or locking has failed."); 4166 set_evac_failure_closure(cl); 4167 // Now do the common part. 4168 handle_evacuation_failure_common(old, m); 4169 // Reset to NULL. 4170 set_evac_failure_closure(NULL); 4171 } else { 4172 // The lock is already held, and this is recursive. 4173 assert(_drain_in_progress, "This should only be the recursive case."); 4174 handle_evacuation_failure_common(old, m); 4175 } 4176 return old; 4177 } else { 4178 // Forward-to-self failed. Either someone else managed to allocate 4179 // space for this object (old != forward_ptr) or they beat us in 4180 // self-forwarding it (old == forward_ptr). 4181 assert(old == forward_ptr || !obj_in_cs(forward_ptr), 4182 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" " 4183 "should not be in the CSet", 4184 (HeapWord*) old, (HeapWord*) forward_ptr)); 4185 return forward_ptr; 4186 } 4187 } 4188 4189 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) { 4190 preserve_mark_if_necessary(old, m); 4191 4192 HeapRegion* r = heap_region_containing(old); 4193 if (!r->evacuation_failed()) { 4194 r->set_evacuation_failed(true); 4195 _hr_printer.evac_failure(r); 4196 } 4197 4198 push_on_evac_failure_scan_stack(old); 4199 4200 if (!_drain_in_progress) { 4201 // prevent recursion in copy_to_survivor_space() 4202 _drain_in_progress = true; 4203 drain_evac_failure_scan_stack(); 4204 _drain_in_progress = false; 4205 } 4206 } 4207 4208 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) { 4209 assert(evacuation_failed(), "Oversaving!"); 4210 // We want to call the "for_promotion_failure" version only in the 4211 // case of a promotion failure. 4212 if (m->must_be_preserved_for_promotion_failure(obj)) { 4213 _objs_with_preserved_marks.push(obj); 4214 _preserved_marks_of_objs.push(m); 4215 } 4216 } 4217 4218 void G1ParCopyHelper::mark_object(oop obj) { 4219 assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet"); 4220 4221 // We know that the object is not moving so it's safe to read its size. 4222 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id); 4223 } 4224 4225 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) { 4226 assert(from_obj->is_forwarded(), "from obj should be forwarded"); 4227 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee"); 4228 assert(from_obj != to_obj, "should not be self-forwarded"); 4229 4230 assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet"); 4231 assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet"); 4232 4233 // The object might be in the process of being copied by another 4234 // worker so we cannot trust that its to-space image is 4235 // well-formed. So we have to read its size from its from-space 4236 // image which we know should not be changing. 4237 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id); 4238 } 4239 4240 template <class T> 4241 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) { 4242 if (_g1->heap_region_containing_raw(new_obj)->is_young()) { 4243 _scanned_klass->record_modified_oops(); 4244 } 4245 } 4246 4247 template <G1Barrier barrier, G1Mark do_mark_object> 4248 template <class T> 4249 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) { 4250 T heap_oop = oopDesc::load_heap_oop(p); 4251 4252 if (oopDesc::is_null(heap_oop)) { 4253 return; 4254 } 4255 4256 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 4257 4258 assert(_worker_id == _par_scan_state->queue_num(), "sanity"); 4259 4260 const InCSetState state = _g1->in_cset_state(obj); 4261 if (state.is_in_cset()) { 4262 oop forwardee; 4263 markOop m = obj->mark(); 4264 if (m->is_marked()) { 4265 forwardee = (oop) m->decode_pointer(); 4266 } else { 4267 forwardee = _par_scan_state->copy_to_survivor_space(state, obj, m); 4268 } 4269 assert(forwardee != NULL, "forwardee should not be NULL"); 4270 oopDesc::encode_store_heap_oop(p, forwardee); 4271 if (do_mark_object != G1MarkNone && forwardee != obj) { 4272 // If the object is self-forwarded we don't need to explicitly 4273 // mark it, the evacuation failure protocol will do so. 4274 mark_forwarded_object(obj, forwardee); 4275 } 4276 4277 if (barrier == G1BarrierKlass) { 4278 do_klass_barrier(p, forwardee); 4279 } 4280 } else { 4281 if (state.is_humongous()) { 4282 _g1->set_humongous_is_live(obj); 4283 } 4284 // The object is not in collection set. If we're a root scanning 4285 // closure during an initial mark pause then attempt to mark the object. 4286 if (do_mark_object == G1MarkFromRoot) { 4287 mark_object(obj); 4288 } 4289 } 4290 4291 if (barrier == G1BarrierEvac) { 4292 _par_scan_state->update_rs(_from, p, _worker_id); 4293 } 4294 } 4295 4296 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(oop* p); 4297 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(narrowOop* p); 4298 4299 class G1ParEvacuateFollowersClosure : public VoidClosure { 4300 protected: 4301 G1CollectedHeap* _g1h; 4302 G1ParScanThreadState* _par_scan_state; 4303 RefToScanQueueSet* _queues; 4304 ParallelTaskTerminator* _terminator; 4305 4306 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 4307 RefToScanQueueSet* queues() { return _queues; } 4308 ParallelTaskTerminator* terminator() { return _terminator; } 4309 4310 public: 4311 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h, 4312 G1ParScanThreadState* par_scan_state, 4313 RefToScanQueueSet* queues, 4314 ParallelTaskTerminator* terminator) 4315 : _g1h(g1h), _par_scan_state(par_scan_state), 4316 _queues(queues), _terminator(terminator) {} 4317 4318 void do_void(); 4319 4320 private: 4321 inline bool offer_termination(); 4322 }; 4323 4324 bool G1ParEvacuateFollowersClosure::offer_termination() { 4325 G1ParScanThreadState* const pss = par_scan_state(); 4326 pss->start_term_time(); 4327 const bool res = terminator()->offer_termination(); 4328 pss->end_term_time(); 4329 return res; 4330 } 4331 4332 void G1ParEvacuateFollowersClosure::do_void() { 4333 G1ParScanThreadState* const pss = par_scan_state(); 4334 pss->trim_queue(); 4335 do { 4336 pss->steal_and_trim_queue(queues()); 4337 } while (!offer_termination()); 4338 } 4339 4340 class G1KlassScanClosure : public KlassClosure { 4341 G1ParCopyHelper* _closure; 4342 bool _process_only_dirty; 4343 int _count; 4344 public: 4345 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty) 4346 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {} 4347 void do_klass(Klass* klass) { 4348 // If the klass has not been dirtied we know that there's 4349 // no references into the young gen and we can skip it. 4350 if (!_process_only_dirty || klass->has_modified_oops()) { 4351 // Clean the klass since we're going to scavenge all the metadata. 4352 klass->clear_modified_oops(); 4353 4354 // Tell the closure that this klass is the Klass to scavenge 4355 // and is the one to dirty if oops are left pointing into the young gen. 4356 _closure->set_scanned_klass(klass); 4357 4358 klass->oops_do(_closure); 4359 4360 _closure->set_scanned_klass(NULL); 4361 } 4362 _count++; 4363 } 4364 }; 4365 4366 class G1CodeBlobClosure : public CodeBlobClosure { 4367 class HeapRegionGatheringOopClosure : public OopClosure { 4368 G1CollectedHeap* _g1h; 4369 OopClosure* _work; 4370 nmethod* _nm; 4371 4372 template <typename T> 4373 void do_oop_work(T* p) { 4374 _work->do_oop(p); 4375 T oop_or_narrowoop = oopDesc::load_heap_oop(p); 4376 if (!oopDesc::is_null(oop_or_narrowoop)) { 4377 oop o = oopDesc::decode_heap_oop_not_null(oop_or_narrowoop); 4378 HeapRegion* hr = _g1h->heap_region_containing_raw(o); 4379 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"); 4380 hr->add_strong_code_root(_nm); 4381 } 4382 } 4383 4384 public: 4385 HeapRegionGatheringOopClosure(OopClosure* oc) : _g1h(G1CollectedHeap::heap()), _work(oc), _nm(NULL) {} 4386 4387 void do_oop(oop* o) { 4388 do_oop_work(o); 4389 } 4390 4391 void do_oop(narrowOop* o) { 4392 do_oop_work(o); 4393 } 4394 4395 void set_nm(nmethod* nm) { 4396 _nm = nm; 4397 } 4398 }; 4399 4400 HeapRegionGatheringOopClosure _oc; 4401 public: 4402 G1CodeBlobClosure(OopClosure* oc) : _oc(oc) {} 4403 4404 void do_code_blob(CodeBlob* cb) { 4405 nmethod* nm = cb->as_nmethod_or_null(); 4406 if (nm != NULL) { 4407 if (!nm->test_set_oops_do_mark()) { 4408 _oc.set_nm(nm); 4409 nm->oops_do(&_oc); 4410 nm->fix_oop_relocations(); 4411 } 4412 } 4413 } 4414 }; 4415 4416 class G1ParTask : public AbstractGangTask { 4417 protected: 4418 G1CollectedHeap* _g1h; 4419 RefToScanQueueSet *_queues; 4420 ParallelTaskTerminator _terminator; 4421 uint _n_workers; 4422 4423 Mutex _stats_lock; 4424 Mutex* stats_lock() { return &_stats_lock; } 4425 4426 public: 4427 G1ParTask(G1CollectedHeap* g1h, RefToScanQueueSet *task_queues) 4428 : AbstractGangTask("G1 collection"), 4429 _g1h(g1h), 4430 _queues(task_queues), 4431 _terminator(0, _queues), 4432 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true) 4433 {} 4434 4435 RefToScanQueueSet* queues() { return _queues; } 4436 4437 RefToScanQueue *work_queue(int i) { 4438 return queues()->queue(i); 4439 } 4440 4441 ParallelTaskTerminator* terminator() { return &_terminator; } 4442 4443 virtual void set_for_termination(int active_workers) { 4444 // This task calls set_n_termination() in par_non_clean_card_iterate_work() 4445 // in the young space (_par_seq_tasks) in the G1 heap 4446 // for SequentialSubTasksDone. 4447 // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap 4448 // both of which need setting by set_n_termination(). 4449 _g1h->SharedHeap::set_n_termination(active_workers); 4450 _g1h->set_n_termination(active_workers); 4451 terminator()->reset_for_reuse(active_workers); 4452 _n_workers = active_workers; 4453 } 4454 4455 // Helps out with CLD processing. 4456 // 4457 // During InitialMark we need to: 4458 // 1) Scavenge all CLDs for the young GC. 4459 // 2) Mark all objects directly reachable from strong CLDs. 4460 template <G1Mark do_mark_object> 4461 class G1CLDClosure : public CLDClosure { 4462 G1ParCopyClosure<G1BarrierNone, do_mark_object>* _oop_closure; 4463 G1ParCopyClosure<G1BarrierKlass, do_mark_object> _oop_in_klass_closure; 4464 G1KlassScanClosure _klass_in_cld_closure; 4465 bool _claim; 4466 4467 public: 4468 G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure, 4469 bool only_young, bool claim) 4470 : _oop_closure(oop_closure), 4471 _oop_in_klass_closure(oop_closure->g1(), 4472 oop_closure->pss(), 4473 oop_closure->rp()), 4474 _klass_in_cld_closure(&_oop_in_klass_closure, only_young), 4475 _claim(claim) { 4476 4477 } 4478 4479 void do_cld(ClassLoaderData* cld) { 4480 cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim); 4481 } 4482 }; 4483 4484 void work(uint worker_id) { 4485 if (worker_id >= _n_workers) return; // no work needed this round 4486 4487 double start_time_ms = os::elapsedTime() * 1000.0; 4488 _g1h->g1_policy()->phase_times()->record_gc_worker_start_time(worker_id, start_time_ms); 4489 4490 { 4491 ResourceMark rm; 4492 HandleMark hm; 4493 4494 ReferenceProcessor* rp = _g1h->ref_processor_stw(); 4495 4496 G1ParScanThreadState pss(_g1h, worker_id, rp); 4497 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp); 4498 4499 pss.set_evac_failure_closure(&evac_failure_cl); 4500 4501 bool only_young = _g1h->g1_policy()->gcs_are_young(); 4502 4503 // Non-IM young GC. 4504 G1ParCopyClosure<G1BarrierNone, G1MarkNone> scan_only_root_cl(_g1h, &pss, rp); 4505 G1CLDClosure<G1MarkNone> scan_only_cld_cl(&scan_only_root_cl, 4506 only_young, // Only process dirty klasses. 4507 false); // No need to claim CLDs. 4508 // IM young GC. 4509 // Strong roots closures. 4510 G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot> scan_mark_root_cl(_g1h, &pss, rp); 4511 G1CLDClosure<G1MarkFromRoot> scan_mark_cld_cl(&scan_mark_root_cl, 4512 false, // Process all klasses. 4513 true); // Need to claim CLDs. 4514 // Weak roots closures. 4515 G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, &pss, rp); 4516 G1CLDClosure<G1MarkPromotedFromRoot> scan_mark_weak_cld_cl(&scan_mark_weak_root_cl, 4517 false, // Process all klasses. 4518 true); // Need to claim CLDs. 4519 4520 G1CodeBlobClosure scan_only_code_cl(&scan_only_root_cl); 4521 G1CodeBlobClosure scan_mark_code_cl(&scan_mark_root_cl); 4522 // IM Weak code roots are handled later. 4523 4524 OopClosure* strong_root_cl; 4525 OopClosure* weak_root_cl; 4526 CLDClosure* strong_cld_cl; 4527 CLDClosure* weak_cld_cl; 4528 CodeBlobClosure* strong_code_cl; 4529 4530 if (_g1h->g1_policy()->during_initial_mark_pause()) { 4531 // We also need to mark copied objects. 4532 strong_root_cl = &scan_mark_root_cl; 4533 strong_cld_cl = &scan_mark_cld_cl; 4534 strong_code_cl = &scan_mark_code_cl; 4535 if (ClassUnloadingWithConcurrentMark) { 4536 weak_root_cl = &scan_mark_weak_root_cl; 4537 weak_cld_cl = &scan_mark_weak_cld_cl; 4538 } else { 4539 weak_root_cl = &scan_mark_root_cl; 4540 weak_cld_cl = &scan_mark_cld_cl; 4541 } 4542 } else { 4543 strong_root_cl = &scan_only_root_cl; 4544 weak_root_cl = &scan_only_root_cl; 4545 strong_cld_cl = &scan_only_cld_cl; 4546 weak_cld_cl = &scan_only_cld_cl; 4547 strong_code_cl = &scan_only_code_cl; 4548 } 4549 4550 4551 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss); 4552 4553 pss.start_strong_roots(); 4554 _g1h->g1_process_roots(strong_root_cl, 4555 weak_root_cl, 4556 &push_heap_rs_cl, 4557 strong_cld_cl, 4558 weak_cld_cl, 4559 strong_code_cl, 4560 worker_id); 4561 4562 pss.end_strong_roots(); 4563 4564 { 4565 double start = os::elapsedTime(); 4566 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator); 4567 evac.do_void(); 4568 double elapsed_ms = (os::elapsedTime()-start)*1000.0; 4569 double term_ms = pss.term_time()*1000.0; 4570 _g1h->g1_policy()->phase_times()->add_obj_copy_time(worker_id, elapsed_ms-term_ms); 4571 _g1h->g1_policy()->phase_times()->record_termination(worker_id, term_ms, pss.term_attempts()); 4572 } 4573 _g1h->g1_policy()->record_thread_age_table(pss.age_table()); 4574 _g1h->update_surviving_young_words(pss.surviving_young_words()+1); 4575 4576 if (PrintTerminationStats) { 4577 MutexLocker x(stats_lock()); 4578 pss.print_termination_stats(worker_id); 4579 } 4580 4581 assert(pss.queue_is_empty(), "should be empty"); 4582 4583 // Close the inner scope so that the ResourceMark and HandleMark 4584 // destructors are executed here and are included as part of the 4585 // "GC Worker Time". 4586 } 4587 4588 double end_time_ms = os::elapsedTime() * 1000.0; 4589 _g1h->g1_policy()->phase_times()->record_gc_worker_end_time(worker_id, end_time_ms); 4590 } 4591 }; 4592 4593 // *** Common G1 Evacuation Stuff 4594 4595 // This method is run in a GC worker. 4596 4597 void 4598 G1CollectedHeap:: 4599 g1_process_roots(OopClosure* scan_non_heap_roots, 4600 OopClosure* scan_non_heap_weak_roots, 4601 G1ParPushHeapRSClosure* scan_rs, 4602 CLDClosure* scan_strong_clds, 4603 CLDClosure* scan_weak_clds, 4604 CodeBlobClosure* scan_strong_code, 4605 uint worker_i) { 4606 4607 // First scan the shared roots. 4608 double ext_roots_start = os::elapsedTime(); 4609 double closure_app_time_sec = 0.0; 4610 4611 bool during_im = _g1h->g1_policy()->during_initial_mark_pause(); 4612 bool trace_metadata = during_im && ClassUnloadingWithConcurrentMark; 4613 4614 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots); 4615 BufferingOopClosure buf_scan_non_heap_weak_roots(scan_non_heap_weak_roots); 4616 4617 process_roots(false, // no scoping; this is parallel code 4618 SharedHeap::SO_None, 4619 &buf_scan_non_heap_roots, 4620 &buf_scan_non_heap_weak_roots, 4621 scan_strong_clds, 4622 // Unloading Initial Marks handle the weak CLDs separately. 4623 (trace_metadata ? NULL : scan_weak_clds), 4624 scan_strong_code); 4625 4626 // Now the CM ref_processor roots. 4627 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) { 4628 // We need to treat the discovered reference lists of the 4629 // concurrent mark ref processor as roots and keep entries 4630 // (which are added by the marking threads) on them live 4631 // until they can be processed at the end of marking. 4632 ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots); 4633 } 4634 4635 if (trace_metadata) { 4636 // Barrier to make sure all workers passed 4637 // the strong CLD and strong nmethods phases. 4638 active_strong_roots_scope()->wait_until_all_workers_done_with_threads(n_par_threads()); 4639 4640 // Now take the complement of the strong CLDs. 4641 ClassLoaderDataGraph::roots_cld_do(NULL, scan_weak_clds); 4642 } 4643 4644 // Finish up any enqueued closure apps (attributed as object copy time). 4645 buf_scan_non_heap_roots.done(); 4646 buf_scan_non_heap_weak_roots.done(); 4647 4648 double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds() 4649 + buf_scan_non_heap_weak_roots.closure_app_seconds(); 4650 4651 g1_policy()->phase_times()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0); 4652 4653 double ext_root_time_ms = 4654 ((os::elapsedTime() - ext_roots_start) - obj_copy_time_sec) * 1000.0; 4655 4656 g1_policy()->phase_times()->record_ext_root_scan_time(worker_i, ext_root_time_ms); 4657 4658 // During conc marking we have to filter the per-thread SATB buffers 4659 // to make sure we remove any oops into the CSet (which will show up 4660 // as implicitly live). 4661 double satb_filtering_ms = 0.0; 4662 if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers)) { 4663 if (mark_in_progress()) { 4664 double satb_filter_start = os::elapsedTime(); 4665 4666 JavaThread::satb_mark_queue_set().filter_thread_buffers(); 4667 4668 satb_filtering_ms = (os::elapsedTime() - satb_filter_start) * 1000.0; 4669 } 4670 } 4671 g1_policy()->phase_times()->record_satb_filtering_time(worker_i, satb_filtering_ms); 4672 4673 // Now scan the complement of the collection set. 4674 G1CodeBlobClosure scavenge_cs_nmethods(scan_non_heap_weak_roots); 4675 4676 g1_rem_set()->oops_into_collection_set_do(scan_rs, &scavenge_cs_nmethods, worker_i); 4677 4678 _process_strong_tasks->all_tasks_completed(); 4679 } 4680 4681 class G1StringSymbolTableUnlinkTask : public AbstractGangTask { 4682 private: 4683 BoolObjectClosure* _is_alive; 4684 int _initial_string_table_size; 4685 int _initial_symbol_table_size; 4686 4687 bool _process_strings; 4688 int _strings_processed; 4689 int _strings_removed; 4690 4691 bool _process_symbols; 4692 int _symbols_processed; 4693 int _symbols_removed; 4694 4695 public: 4696 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) : 4697 AbstractGangTask("String/Symbol Unlinking"), 4698 _is_alive(is_alive), 4699 _process_strings(process_strings), _strings_processed(0), _strings_removed(0), 4700 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) { 4701 4702 _initial_string_table_size = StringTable::the_table()->table_size(); 4703 _initial_symbol_table_size = SymbolTable::the_table()->table_size(); 4704 if (process_strings) { 4705 StringTable::clear_parallel_claimed_index(); 4706 } 4707 if (process_symbols) { 4708 SymbolTable::clear_parallel_claimed_index(); 4709 } 4710 } 4711 4712 ~G1StringSymbolTableUnlinkTask() { 4713 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size, 4714 err_msg("claim value %d after unlink less than initial string table size %d", 4715 StringTable::parallel_claimed_index(), _initial_string_table_size)); 4716 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size, 4717 err_msg("claim value %d after unlink less than initial symbol table size %d", 4718 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size)); 4719 4720 if (G1TraceStringSymbolTableScrubbing) { 4721 gclog_or_tty->print_cr("Cleaned string and symbol table, " 4722 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, " 4723 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed", 4724 strings_processed(), strings_removed(), 4725 symbols_processed(), symbols_removed()); 4726 } 4727 } 4728 4729 void work(uint worker_id) { 4730 int strings_processed = 0; 4731 int strings_removed = 0; 4732 int symbols_processed = 0; 4733 int symbols_removed = 0; 4734 if (_process_strings) { 4735 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed); 4736 Atomic::add(strings_processed, &_strings_processed); 4737 Atomic::add(strings_removed, &_strings_removed); 4738 } 4739 if (_process_symbols) { 4740 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed); 4741 Atomic::add(symbols_processed, &_symbols_processed); 4742 Atomic::add(symbols_removed, &_symbols_removed); 4743 } 4744 } 4745 4746 size_t strings_processed() const { return (size_t)_strings_processed; } 4747 size_t strings_removed() const { return (size_t)_strings_removed; } 4748 4749 size_t symbols_processed() const { return (size_t)_symbols_processed; } 4750 size_t symbols_removed() const { return (size_t)_symbols_removed; } 4751 }; 4752 4753 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC { 4754 private: 4755 static Monitor* _lock; 4756 4757 BoolObjectClosure* const _is_alive; 4758 const bool _unloading_occurred; 4759 const uint _num_workers; 4760 4761 // Variables used to claim nmethods. 4762 nmethod* _first_nmethod; 4763 volatile nmethod* _claimed_nmethod; 4764 4765 // The list of nmethods that need to be processed by the second pass. 4766 volatile nmethod* _postponed_list; 4767 volatile uint _num_entered_barrier; 4768 4769 public: 4770 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) : 4771 _is_alive(is_alive), 4772 _unloading_occurred(unloading_occurred), 4773 _num_workers(num_workers), 4774 _first_nmethod(NULL), 4775 _claimed_nmethod(NULL), 4776 _postponed_list(NULL), 4777 _num_entered_barrier(0) 4778 { 4779 nmethod::increase_unloading_clock(); 4780 // Get first alive nmethod 4781 NMethodIterator iter = NMethodIterator(); 4782 if(iter.next_alive()) { 4783 _first_nmethod = iter.method(); 4784 } 4785 _claimed_nmethod = (volatile nmethod*)_first_nmethod; 4786 } 4787 4788 ~G1CodeCacheUnloadingTask() { 4789 CodeCache::verify_clean_inline_caches(); 4790 4791 CodeCache::set_needs_cache_clean(false); 4792 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be"); 4793 4794 CodeCache::verify_icholder_relocations(); 4795 } 4796 4797 private: 4798 void add_to_postponed_list(nmethod* nm) { 4799 nmethod* old; 4800 do { 4801 old = (nmethod*)_postponed_list; 4802 nm->set_unloading_next(old); 4803 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old); 4804 } 4805 4806 void clean_nmethod(nmethod* nm) { 4807 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred); 4808 4809 if (postponed) { 4810 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet. 4811 add_to_postponed_list(nm); 4812 } 4813 4814 // Mark that this thread has been cleaned/unloaded. 4815 // After this call, it will be safe to ask if this nmethod was unloaded or not. 4816 nm->set_unloading_clock(nmethod::global_unloading_clock()); 4817 } 4818 4819 void clean_nmethod_postponed(nmethod* nm) { 4820 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred); 4821 } 4822 4823 static const int MaxClaimNmethods = 16; 4824 4825 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) { 4826 nmethod* first; 4827 NMethodIterator last; 4828 4829 do { 4830 *num_claimed_nmethods = 0; 4831 4832 first = (nmethod*)_claimed_nmethod; 4833 last = NMethodIterator(first); 4834 4835 if (first != NULL) { 4836 4837 for (int i = 0; i < MaxClaimNmethods; i++) { 4838 if (!last.next_alive()) { 4839 break; 4840 } 4841 claimed_nmethods[i] = last.method(); 4842 (*num_claimed_nmethods)++; 4843 } 4844 } 4845 4846 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first); 4847 } 4848 4849 nmethod* claim_postponed_nmethod() { 4850 nmethod* claim; 4851 nmethod* next; 4852 4853 do { 4854 claim = (nmethod*)_postponed_list; 4855 if (claim == NULL) { 4856 return NULL; 4857 } 4858 4859 next = claim->unloading_next(); 4860 4861 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim); 4862 4863 return claim; 4864 } 4865 4866 public: 4867 // Mark that we're done with the first pass of nmethod cleaning. 4868 void barrier_mark(uint worker_id) { 4869 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 4870 _num_entered_barrier++; 4871 if (_num_entered_barrier == _num_workers) { 4872 ml.notify_all(); 4873 } 4874 } 4875 4876 // See if we have to wait for the other workers to 4877 // finish their first-pass nmethod cleaning work. 4878 void barrier_wait(uint worker_id) { 4879 if (_num_entered_barrier < _num_workers) { 4880 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 4881 while (_num_entered_barrier < _num_workers) { 4882 ml.wait(Mutex::_no_safepoint_check_flag, 0, false); 4883 } 4884 } 4885 } 4886 4887 // Cleaning and unloading of nmethods. Some work has to be postponed 4888 // to the second pass, when we know which nmethods survive. 4889 void work_first_pass(uint worker_id) { 4890 // The first nmethods is claimed by the first worker. 4891 if (worker_id == 0 && _first_nmethod != NULL) { 4892 clean_nmethod(_first_nmethod); 4893 _first_nmethod = NULL; 4894 } 4895 4896 int num_claimed_nmethods; 4897 nmethod* claimed_nmethods[MaxClaimNmethods]; 4898 4899 while (true) { 4900 claim_nmethods(claimed_nmethods, &num_claimed_nmethods); 4901 4902 if (num_claimed_nmethods == 0) { 4903 break; 4904 } 4905 4906 for (int i = 0; i < num_claimed_nmethods; i++) { 4907 clean_nmethod(claimed_nmethods[i]); 4908 } 4909 } 4910 4911 // The nmethod cleaning helps out and does the CodeCache part of MetadataOnStackMark. 4912 // Need to retire the buffers now that this thread has stopped cleaning nmethods. 4913 MetadataOnStackMark::retire_buffer_for_thread(Thread::current()); 4914 } 4915 4916 void work_second_pass(uint worker_id) { 4917 nmethod* nm; 4918 // Take care of postponed nmethods. 4919 while ((nm = claim_postponed_nmethod()) != NULL) { 4920 clean_nmethod_postponed(nm); 4921 } 4922 } 4923 }; 4924 4925 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never); 4926 4927 class G1KlassCleaningTask : public StackObj { 4928 BoolObjectClosure* _is_alive; 4929 volatile jint _clean_klass_tree_claimed; 4930 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator; 4931 4932 public: 4933 G1KlassCleaningTask(BoolObjectClosure* is_alive) : 4934 _is_alive(is_alive), 4935 _clean_klass_tree_claimed(0), 4936 _klass_iterator() { 4937 } 4938 4939 private: 4940 bool claim_clean_klass_tree_task() { 4941 if (_clean_klass_tree_claimed) { 4942 return false; 4943 } 4944 4945 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0; 4946 } 4947 4948 InstanceKlass* claim_next_klass() { 4949 Klass* klass; 4950 do { 4951 klass =_klass_iterator.next_klass(); 4952 } while (klass != NULL && !klass->oop_is_instance()); 4953 4954 return (InstanceKlass*)klass; 4955 } 4956 4957 public: 4958 4959 void clean_klass(InstanceKlass* ik) { 4960 ik->clean_implementors_list(_is_alive); 4961 ik->clean_method_data(_is_alive); 4962 4963 // G1 specific cleanup work that has 4964 // been moved here to be done in parallel. 4965 ik->clean_dependent_nmethods(); 4966 if (JvmtiExport::has_redefined_a_class()) { 4967 InstanceKlass::purge_previous_versions(ik); 4968 } 4969 } 4970 4971 void work() { 4972 ResourceMark rm; 4973 4974 // One worker will clean the subklass/sibling klass tree. 4975 if (claim_clean_klass_tree_task()) { 4976 Klass::clean_subklass_tree(_is_alive); 4977 } 4978 4979 // All workers will help cleaning the classes, 4980 InstanceKlass* klass; 4981 while ((klass = claim_next_klass()) != NULL) { 4982 clean_klass(klass); 4983 } 4984 } 4985 }; 4986 4987 // To minimize the remark pause times, the tasks below are done in parallel. 4988 class G1ParallelCleaningTask : public AbstractGangTask { 4989 private: 4990 G1StringSymbolTableUnlinkTask _string_symbol_task; 4991 G1CodeCacheUnloadingTask _code_cache_task; 4992 G1KlassCleaningTask _klass_cleaning_task; 4993 4994 public: 4995 // The constructor is run in the VMThread. 4996 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) : 4997 AbstractGangTask("Parallel Cleaning"), 4998 _string_symbol_task(is_alive, process_strings, process_symbols), 4999 _code_cache_task(num_workers, is_alive, unloading_occurred), 5000 _klass_cleaning_task(is_alive) { 5001 } 5002 5003 void pre_work_verification() { 5004 assert(!MetadataOnStackMark::has_buffer_for_thread(Thread::current()), "Should be empty"); 5005 } 5006 5007 void post_work_verification() { 5008 assert(!MetadataOnStackMark::has_buffer_for_thread(Thread::current()), "Should be empty"); 5009 } 5010 5011 // The parallel work done by all worker threads. 5012 void work(uint worker_id) { 5013 pre_work_verification(); 5014 5015 // Do first pass of code cache cleaning. 5016 _code_cache_task.work_first_pass(worker_id); 5017 5018 // Let the threads mark that the first pass is done. 5019 _code_cache_task.barrier_mark(worker_id); 5020 5021 // Clean the Strings and Symbols. 5022 _string_symbol_task.work(worker_id); 5023 5024 // Wait for all workers to finish the first code cache cleaning pass. 5025 _code_cache_task.barrier_wait(worker_id); 5026 5027 // Do the second code cache cleaning work, which realize on 5028 // the liveness information gathered during the first pass. 5029 _code_cache_task.work_second_pass(worker_id); 5030 5031 // Clean all klasses that were not unloaded. 5032 _klass_cleaning_task.work(); 5033 5034 post_work_verification(); 5035 } 5036 }; 5037 5038 5039 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive, 5040 bool process_strings, 5041 bool process_symbols, 5042 bool class_unloading_occurred) { 5043 uint n_workers = workers()->active_workers(); 5044 5045 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, 5046 n_workers, class_unloading_occurred); 5047 set_par_threads(n_workers); 5048 workers()->run_task(&g1_unlink_task); 5049 set_par_threads(0); 5050 } 5051 5052 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive, 5053 bool process_strings, bool process_symbols) { 5054 { 5055 uint n_workers = _g1h->workers()->active_workers(); 5056 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols); 5057 set_par_threads(n_workers); 5058 workers()->run_task(&g1_unlink_task); 5059 set_par_threads(0); 5060 } 5061 5062 if (G1StringDedup::is_enabled()) { 5063 G1StringDedup::unlink(is_alive); 5064 } 5065 } 5066 5067 class G1RedirtyLoggedCardsTask : public AbstractGangTask { 5068 private: 5069 DirtyCardQueueSet* _queue; 5070 public: 5071 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { } 5072 5073 virtual void work(uint worker_id) { 5074 double start_time = os::elapsedTime(); 5075 5076 RedirtyLoggedCardTableEntryClosure cl; 5077 _queue->par_apply_closure_to_all_completed_buffers(&cl); 5078 5079 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times(); 5080 timer->record_redirty_logged_cards_time_ms(worker_id, (os::elapsedTime() - start_time) * 1000.0); 5081 timer->record_redirty_logged_cards_processed_cards(worker_id, cl.num_processed()); 5082 } 5083 }; 5084 5085 void G1CollectedHeap::redirty_logged_cards() { 5086 double redirty_logged_cards_start = os::elapsedTime(); 5087 5088 uint n_workers = _g1h->workers()->active_workers(); 5089 5090 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set()); 5091 dirty_card_queue_set().reset_for_par_iteration(); 5092 set_par_threads(n_workers); 5093 workers()->run_task(&redirty_task); 5094 set_par_threads(0); 5095 5096 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set(); 5097 dcq.merge_bufferlists(&dirty_card_queue_set()); 5098 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed"); 5099 5100 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0); 5101 } 5102 5103 // Weak Reference Processing support 5104 5105 // An always "is_alive" closure that is used to preserve referents. 5106 // If the object is non-null then it's alive. Used in the preservation 5107 // of referent objects that are pointed to by reference objects 5108 // discovered by the CM ref processor. 5109 class G1AlwaysAliveClosure: public BoolObjectClosure { 5110 G1CollectedHeap* _g1; 5111 public: 5112 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 5113 bool do_object_b(oop p) { 5114 if (p != NULL) { 5115 return true; 5116 } 5117 return false; 5118 } 5119 }; 5120 5121 bool G1STWIsAliveClosure::do_object_b(oop p) { 5122 // An object is reachable if it is outside the collection set, 5123 // or is inside and copied. 5124 return !_g1->obj_in_cs(p) || p->is_forwarded(); 5125 } 5126 5127 // Non Copying Keep Alive closure 5128 class G1KeepAliveClosure: public OopClosure { 5129 G1CollectedHeap* _g1; 5130 public: 5131 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 5132 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } 5133 void do_oop(oop* p) { 5134 oop obj = *p; 5135 assert(obj != NULL, "the caller should have filtered out NULL values"); 5136 5137 const InCSetState cset_state = _g1->in_cset_state(obj); 5138 if (!cset_state.is_in_cset_or_humongous()) { 5139 return; 5140 } 5141 if (cset_state.is_in_cset()) { 5142 assert( obj->is_forwarded(), "invariant" ); 5143 *p = obj->forwardee(); 5144 } else { 5145 assert(!obj->is_forwarded(), "invariant" ); 5146 assert(cset_state.is_humongous(), 5147 err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state.value())); 5148 _g1->set_humongous_is_live(obj); 5149 } 5150 } 5151 }; 5152 5153 // Copying Keep Alive closure - can be called from both 5154 // serial and parallel code as long as different worker 5155 // threads utilize different G1ParScanThreadState instances 5156 // and different queues. 5157 5158 class G1CopyingKeepAliveClosure: public OopClosure { 5159 G1CollectedHeap* _g1h; 5160 OopClosure* _copy_non_heap_obj_cl; 5161 G1ParScanThreadState* _par_scan_state; 5162 5163 public: 5164 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, 5165 OopClosure* non_heap_obj_cl, 5166 G1ParScanThreadState* pss): 5167 _g1h(g1h), 5168 _copy_non_heap_obj_cl(non_heap_obj_cl), 5169 _par_scan_state(pss) 5170 {} 5171 5172 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 5173 virtual void do_oop( oop* p) { do_oop_work(p); } 5174 5175 template <class T> void do_oop_work(T* p) { 5176 oop obj = oopDesc::load_decode_heap_oop(p); 5177 5178 if (_g1h->is_in_cset_or_humongous(obj)) { 5179 // If the referent object has been forwarded (either copied 5180 // to a new location or to itself in the event of an 5181 // evacuation failure) then we need to update the reference 5182 // field and, if both reference and referent are in the G1 5183 // heap, update the RSet for the referent. 5184 // 5185 // If the referent has not been forwarded then we have to keep 5186 // it alive by policy. Therefore we have copy the referent. 5187 // 5188 // If the reference field is in the G1 heap then we can push 5189 // on the PSS queue. When the queue is drained (after each 5190 // phase of reference processing) the object and it's followers 5191 // will be copied, the reference field set to point to the 5192 // new location, and the RSet updated. Otherwise we need to 5193 // use the the non-heap or metadata closures directly to copy 5194 // the referent object and update the pointer, while avoiding 5195 // updating the RSet. 5196 5197 if (_g1h->is_in_g1_reserved(p)) { 5198 _par_scan_state->push_on_queue(p); 5199 } else { 5200 assert(!Metaspace::contains((const void*)p), 5201 err_msg("Unexpectedly found a pointer from metadata: " 5202 PTR_FORMAT, p)); 5203 _copy_non_heap_obj_cl->do_oop(p); 5204 } 5205 } 5206 } 5207 }; 5208 5209 // Serial drain queue closure. Called as the 'complete_gc' 5210 // closure for each discovered list in some of the 5211 // reference processing phases. 5212 5213 class G1STWDrainQueueClosure: public VoidClosure { 5214 protected: 5215 G1CollectedHeap* _g1h; 5216 G1ParScanThreadState* _par_scan_state; 5217 5218 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 5219 5220 public: 5221 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : 5222 _g1h(g1h), 5223 _par_scan_state(pss) 5224 { } 5225 5226 void do_void() { 5227 G1ParScanThreadState* const pss = par_scan_state(); 5228 pss->trim_queue(); 5229 } 5230 }; 5231 5232 // Parallel Reference Processing closures 5233 5234 // Implementation of AbstractRefProcTaskExecutor for parallel reference 5235 // processing during G1 evacuation pauses. 5236 5237 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 5238 private: 5239 G1CollectedHeap* _g1h; 5240 RefToScanQueueSet* _queues; 5241 FlexibleWorkGang* _workers; 5242 int _active_workers; 5243 5244 public: 5245 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, 5246 FlexibleWorkGang* workers, 5247 RefToScanQueueSet *task_queues, 5248 int n_workers) : 5249 _g1h(g1h), 5250 _queues(task_queues), 5251 _workers(workers), 5252 _active_workers(n_workers) 5253 { 5254 assert(n_workers > 0, "shouldn't call this otherwise"); 5255 } 5256 5257 // Executes the given task using concurrent marking worker threads. 5258 virtual void execute(ProcessTask& task); 5259 virtual void execute(EnqueueTask& task); 5260 }; 5261 5262 // Gang task for possibly parallel reference processing 5263 5264 class G1STWRefProcTaskProxy: public AbstractGangTask { 5265 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 5266 ProcessTask& _proc_task; 5267 G1CollectedHeap* _g1h; 5268 RefToScanQueueSet *_task_queues; 5269 ParallelTaskTerminator* _terminator; 5270 5271 public: 5272 G1STWRefProcTaskProxy(ProcessTask& proc_task, 5273 G1CollectedHeap* g1h, 5274 RefToScanQueueSet *task_queues, 5275 ParallelTaskTerminator* terminator) : 5276 AbstractGangTask("Process reference objects in parallel"), 5277 _proc_task(proc_task), 5278 _g1h(g1h), 5279 _task_queues(task_queues), 5280 _terminator(terminator) 5281 {} 5282 5283 virtual void work(uint worker_id) { 5284 // The reference processing task executed by a single worker. 5285 ResourceMark rm; 5286 HandleMark hm; 5287 5288 G1STWIsAliveClosure is_alive(_g1h); 5289 5290 G1ParScanThreadState pss(_g1h, worker_id, NULL); 5291 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL); 5292 5293 pss.set_evac_failure_closure(&evac_failure_cl); 5294 5295 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL); 5296 5297 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL); 5298 5299 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5300 5301 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5302 // We also need to mark copied objects. 5303 copy_non_heap_cl = ©_mark_non_heap_cl; 5304 } 5305 5306 // Keep alive closure. 5307 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss); 5308 5309 // Complete GC closure 5310 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator); 5311 5312 // Call the reference processing task's work routine. 5313 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); 5314 5315 // Note we cannot assert that the refs array is empty here as not all 5316 // of the processing tasks (specifically phase2 - pp2_work) execute 5317 // the complete_gc closure (which ordinarily would drain the queue) so 5318 // the queue may not be empty. 5319 } 5320 }; 5321 5322 // Driver routine for parallel reference processing. 5323 // Creates an instance of the ref processing gang 5324 // task and has the worker threads execute it. 5325 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) { 5326 assert(_workers != NULL, "Need parallel worker threads."); 5327 5328 ParallelTaskTerminator terminator(_active_workers, _queues); 5329 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator); 5330 5331 _g1h->set_par_threads(_active_workers); 5332 _workers->run_task(&proc_task_proxy); 5333 _g1h->set_par_threads(0); 5334 } 5335 5336 // Gang task for parallel reference enqueueing. 5337 5338 class G1STWRefEnqueueTaskProxy: public AbstractGangTask { 5339 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; 5340 EnqueueTask& _enq_task; 5341 5342 public: 5343 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) : 5344 AbstractGangTask("Enqueue reference objects in parallel"), 5345 _enq_task(enq_task) 5346 { } 5347 5348 virtual void work(uint worker_id) { 5349 _enq_task.work(worker_id); 5350 } 5351 }; 5352 5353 // Driver routine for parallel reference enqueueing. 5354 // Creates an instance of the ref enqueueing gang 5355 // task and has the worker threads execute it. 5356 5357 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) { 5358 assert(_workers != NULL, "Need parallel worker threads."); 5359 5360 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task); 5361 5362 _g1h->set_par_threads(_active_workers); 5363 _workers->run_task(&enq_task_proxy); 5364 _g1h->set_par_threads(0); 5365 } 5366 5367 // End of weak reference support closures 5368 5369 // Abstract task used to preserve (i.e. copy) any referent objects 5370 // that are in the collection set and are pointed to by reference 5371 // objects discovered by the CM ref processor. 5372 5373 class G1ParPreserveCMReferentsTask: public AbstractGangTask { 5374 protected: 5375 G1CollectedHeap* _g1h; 5376 RefToScanQueueSet *_queues; 5377 ParallelTaskTerminator _terminator; 5378 uint _n_workers; 5379 5380 public: 5381 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) : 5382 AbstractGangTask("ParPreserveCMReferents"), 5383 _g1h(g1h), 5384 _queues(task_queues), 5385 _terminator(workers, _queues), 5386 _n_workers(workers) 5387 { } 5388 5389 void work(uint worker_id) { 5390 ResourceMark rm; 5391 HandleMark hm; 5392 5393 G1ParScanThreadState pss(_g1h, worker_id, NULL); 5394 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL); 5395 5396 pss.set_evac_failure_closure(&evac_failure_cl); 5397 5398 assert(pss.queue_is_empty(), "both queue and overflow should be empty"); 5399 5400 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL); 5401 5402 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL); 5403 5404 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5405 5406 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5407 // We also need to mark copied objects. 5408 copy_non_heap_cl = ©_mark_non_heap_cl; 5409 } 5410 5411 // Is alive closure 5412 G1AlwaysAliveClosure always_alive(_g1h); 5413 5414 // Copying keep alive closure. Applied to referent objects that need 5415 // to be copied. 5416 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss); 5417 5418 ReferenceProcessor* rp = _g1h->ref_processor_cm(); 5419 5420 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q(); 5421 uint stride = MIN2(MAX2(_n_workers, 1U), limit); 5422 5423 // limit is set using max_num_q() - which was set using ParallelGCThreads. 5424 // So this must be true - but assert just in case someone decides to 5425 // change the worker ids. 5426 assert(0 <= worker_id && worker_id < limit, "sanity"); 5427 assert(!rp->discovery_is_atomic(), "check this code"); 5428 5429 // Select discovered lists [i, i+stride, i+2*stride,...,limit) 5430 for (uint idx = worker_id; idx < limit; idx += stride) { 5431 DiscoveredList& ref_list = rp->discovered_refs()[idx]; 5432 5433 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive); 5434 while (iter.has_next()) { 5435 // Since discovery is not atomic for the CM ref processor, we 5436 // can see some null referent objects. 5437 iter.load_ptrs(DEBUG_ONLY(true)); 5438 oop ref = iter.obj(); 5439 5440 // This will filter nulls. 5441 if (iter.is_referent_alive()) { 5442 iter.make_referent_alive(); 5443 } 5444 iter.move_to_next(); 5445 } 5446 } 5447 5448 // Drain the queue - which may cause stealing 5449 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator); 5450 drain_queue.do_void(); 5451 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure 5452 assert(pss.queue_is_empty(), "should be"); 5453 } 5454 }; 5455 5456 // Weak Reference processing during an evacuation pause (part 1). 5457 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) { 5458 double ref_proc_start = os::elapsedTime(); 5459 5460 ReferenceProcessor* rp = _ref_processor_stw; 5461 assert(rp->discovery_enabled(), "should have been enabled"); 5462 5463 // Any reference objects, in the collection set, that were 'discovered' 5464 // by the CM ref processor should have already been copied (either by 5465 // applying the external root copy closure to the discovered lists, or 5466 // by following an RSet entry). 5467 // 5468 // But some of the referents, that are in the collection set, that these 5469 // reference objects point to may not have been copied: the STW ref 5470 // processor would have seen that the reference object had already 5471 // been 'discovered' and would have skipped discovering the reference, 5472 // but would not have treated the reference object as a regular oop. 5473 // As a result the copy closure would not have been applied to the 5474 // referent object. 5475 // 5476 // We need to explicitly copy these referent objects - the references 5477 // will be processed at the end of remarking. 5478 // 5479 // We also need to do this copying before we process the reference 5480 // objects discovered by the STW ref processor in case one of these 5481 // referents points to another object which is also referenced by an 5482 // object discovered by the STW ref processor. 5483 5484 assert(no_of_gc_workers == workers()->active_workers(), "Need to reset active GC workers"); 5485 5486 set_par_threads(no_of_gc_workers); 5487 G1ParPreserveCMReferentsTask keep_cm_referents(this, 5488 no_of_gc_workers, 5489 _task_queues); 5490 5491 workers()->run_task(&keep_cm_referents); 5492 5493 set_par_threads(0); 5494 5495 // Closure to test whether a referent is alive. 5496 G1STWIsAliveClosure is_alive(this); 5497 5498 // Even when parallel reference processing is enabled, the processing 5499 // of JNI refs is serial and performed serially by the current thread 5500 // rather than by a worker. The following PSS will be used for processing 5501 // JNI refs. 5502 5503 // Use only a single queue for this PSS. 5504 G1ParScanThreadState pss(this, 0, NULL); 5505 5506 // We do not embed a reference processor in the copying/scanning 5507 // closures while we're actually processing the discovered 5508 // reference objects. 5509 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL); 5510 5511 pss.set_evac_failure_closure(&evac_failure_cl); 5512 5513 assert(pss.queue_is_empty(), "pre-condition"); 5514 5515 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL); 5516 5517 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL); 5518 5519 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5520 5521 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5522 // We also need to mark copied objects. 5523 copy_non_heap_cl = ©_mark_non_heap_cl; 5524 } 5525 5526 // Keep alive closure. 5527 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, &pss); 5528 5529 // Serial Complete GC closure 5530 G1STWDrainQueueClosure drain_queue(this, &pss); 5531 5532 // Setup the soft refs policy... 5533 rp->setup_policy(false); 5534 5535 ReferenceProcessorStats stats; 5536 if (!rp->processing_is_mt()) { 5537 // Serial reference processing... 5538 stats = rp->process_discovered_references(&is_alive, 5539 &keep_alive, 5540 &drain_queue, 5541 NULL, 5542 _gc_timer_stw, 5543 _gc_tracer_stw->gc_id()); 5544 } else { 5545 // Parallel reference processing 5546 assert(rp->num_q() == no_of_gc_workers, "sanity"); 5547 assert(no_of_gc_workers <= rp->max_num_q(), "sanity"); 5548 5549 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers); 5550 stats = rp->process_discovered_references(&is_alive, 5551 &keep_alive, 5552 &drain_queue, 5553 &par_task_executor, 5554 _gc_timer_stw, 5555 _gc_tracer_stw->gc_id()); 5556 } 5557 5558 _gc_tracer_stw->report_gc_reference_stats(stats); 5559 5560 // We have completed copying any necessary live referent objects. 5561 assert(pss.queue_is_empty(), "both queue and overflow should be empty"); 5562 5563 double ref_proc_time = os::elapsedTime() - ref_proc_start; 5564 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 5565 } 5566 5567 // Weak Reference processing during an evacuation pause (part 2). 5568 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) { 5569 double ref_enq_start = os::elapsedTime(); 5570 5571 ReferenceProcessor* rp = _ref_processor_stw; 5572 assert(!rp->discovery_enabled(), "should have been disabled as part of processing"); 5573 5574 // Now enqueue any remaining on the discovered lists on to 5575 // the pending list. 5576 if (!rp->processing_is_mt()) { 5577 // Serial reference processing... 5578 rp->enqueue_discovered_references(); 5579 } else { 5580 // Parallel reference enqueueing 5581 5582 assert(no_of_gc_workers == workers()->active_workers(), 5583 "Need to reset active workers"); 5584 assert(rp->num_q() == no_of_gc_workers, "sanity"); 5585 assert(no_of_gc_workers <= rp->max_num_q(), "sanity"); 5586 5587 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers); 5588 rp->enqueue_discovered_references(&par_task_executor); 5589 } 5590 5591 rp->verify_no_references_recorded(); 5592 assert(!rp->discovery_enabled(), "should have been disabled"); 5593 5594 // FIXME 5595 // CM's reference processing also cleans up the string and symbol tables. 5596 // Should we do that here also? We could, but it is a serial operation 5597 // and could significantly increase the pause time. 5598 5599 double ref_enq_time = os::elapsedTime() - ref_enq_start; 5600 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0); 5601 } 5602 5603 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) { 5604 _expand_heap_after_alloc_failure = true; 5605 _evacuation_failed = false; 5606 5607 // Should G1EvacuationFailureALot be in effect for this GC? 5608 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) 5609 5610 g1_rem_set()->prepare_for_oops_into_collection_set_do(); 5611 5612 // Disable the hot card cache. 5613 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 5614 hot_card_cache->reset_hot_cache_claimed_index(); 5615 hot_card_cache->set_use_cache(false); 5616 5617 uint n_workers; 5618 n_workers = 5619 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 5620 workers()->active_workers(), 5621 Threads::number_of_non_daemon_threads()); 5622 assert(UseDynamicNumberOfGCThreads || 5623 n_workers == workers()->total_workers(), 5624 "If not dynamic should be using all the workers"); 5625 workers()->set_active_workers(n_workers); 5626 set_par_threads(n_workers); 5627 5628 G1ParTask g1_par_task(this, _task_queues); 5629 5630 init_for_evac_failure(NULL); 5631 5632 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty"); 5633 double start_par_time_sec = os::elapsedTime(); 5634 double end_par_time_sec; 5635 5636 { 5637 StrongRootsScope srs(this); 5638 // InitialMark needs claim bits to keep track of the marked-through CLDs. 5639 if (g1_policy()->during_initial_mark_pause()) { 5640 ClassLoaderDataGraph::clear_claimed_marks(); 5641 } 5642 5643 // The individual threads will set their evac-failure closures. 5644 if (PrintTerminationStats) G1ParScanThreadState::print_termination_stats_hdr(); 5645 // These tasks use ShareHeap::_process_strong_tasks 5646 assert(UseDynamicNumberOfGCThreads || 5647 workers()->active_workers() == workers()->total_workers(), 5648 "If not dynamic should be using all the workers"); 5649 workers()->run_task(&g1_par_task); 5650 end_par_time_sec = os::elapsedTime(); 5651 5652 // Closing the inner scope will execute the destructor 5653 // for the StrongRootsScope object. We record the current 5654 // elapsed time before closing the scope so that time 5655 // taken for the SRS destructor is NOT included in the 5656 // reported parallel time. 5657 } 5658 5659 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0; 5660 g1_policy()->phase_times()->record_par_time(par_time_ms); 5661 5662 double code_root_fixup_time_ms = 5663 (os::elapsedTime() - end_par_time_sec) * 1000.0; 5664 g1_policy()->phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms); 5665 5666 set_par_threads(0); 5667 5668 // Process any discovered reference objects - we have 5669 // to do this _before_ we retire the GC alloc regions 5670 // as we may have to copy some 'reachable' referent 5671 // objects (and their reachable sub-graphs) that were 5672 // not copied during the pause. 5673 process_discovered_references(n_workers); 5674 5675 if (G1StringDedup::is_enabled()) { 5676 G1STWIsAliveClosure is_alive(this); 5677 G1KeepAliveClosure keep_alive(this); 5678 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive); 5679 } 5680 5681 _allocator->release_gc_alloc_regions(n_workers, evacuation_info); 5682 g1_rem_set()->cleanup_after_oops_into_collection_set_do(); 5683 5684 // Reset and re-enable the hot card cache. 5685 // Note the counts for the cards in the regions in the 5686 // collection set are reset when the collection set is freed. 5687 hot_card_cache->reset_hot_cache(); 5688 hot_card_cache->set_use_cache(true); 5689 5690 purge_code_root_memory(); 5691 5692 finalize_for_evac_failure(); 5693 5694 if (evacuation_failed()) { 5695 remove_self_forwarding_pointers(); 5696 5697 // Reset the G1EvacuationFailureALot counters and flags 5698 // Note: the values are reset only when an actual 5699 // evacuation failure occurs. 5700 NOT_PRODUCT(reset_evacuation_should_fail();) 5701 } 5702 5703 // Enqueue any remaining references remaining on the STW 5704 // reference processor's discovered lists. We need to do 5705 // this after the card table is cleaned (and verified) as 5706 // the act of enqueueing entries on to the pending list 5707 // will log these updates (and dirty their associated 5708 // cards). We need these updates logged to update any 5709 // RSets. 5710 enqueue_discovered_references(n_workers); 5711 5712 redirty_logged_cards(); 5713 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 5714 } 5715 5716 void G1CollectedHeap::free_region(HeapRegion* hr, 5717 FreeRegionList* free_list, 5718 bool par, 5719 bool locked) { 5720 assert(!hr->is_free(), "the region should not be free"); 5721 assert(!hr->is_empty(), "the region should not be empty"); 5722 assert(_hrm.is_available(hr->hrm_index()), "region should be committed"); 5723 assert(free_list != NULL, "pre-condition"); 5724 5725 if (G1VerifyBitmaps) { 5726 MemRegion mr(hr->bottom(), hr->end()); 5727 concurrent_mark()->clearRangePrevBitmap(mr); 5728 } 5729 5730 // Clear the card counts for this region. 5731 // Note: we only need to do this if the region is not young 5732 // (since we don't refine cards in young regions). 5733 if (!hr->is_young()) { 5734 _cg1r->hot_card_cache()->reset_card_counts(hr); 5735 } 5736 hr->hr_clear(par, true /* clear_space */, locked /* locked */); 5737 free_list->add_ordered(hr); 5738 } 5739 5740 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 5741 FreeRegionList* free_list, 5742 bool par) { 5743 assert(hr->is_starts_humongous(), "this is only for starts humongous regions"); 5744 assert(free_list != NULL, "pre-condition"); 5745 5746 size_t hr_capacity = hr->capacity(); 5747 // We need to read this before we make the region non-humongous, 5748 // otherwise the information will be gone. 5749 uint last_index = hr->last_hc_index(); 5750 hr->clear_humongous(); 5751 free_region(hr, free_list, par); 5752 5753 uint i = hr->hrm_index() + 1; 5754 while (i < last_index) { 5755 HeapRegion* curr_hr = region_at(i); 5756 assert(curr_hr->is_continues_humongous(), "invariant"); 5757 curr_hr->clear_humongous(); 5758 free_region(curr_hr, free_list, par); 5759 i += 1; 5760 } 5761 } 5762 5763 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed, 5764 const HeapRegionSetCount& humongous_regions_removed) { 5765 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) { 5766 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 5767 _old_set.bulk_remove(old_regions_removed); 5768 _humongous_set.bulk_remove(humongous_regions_removed); 5769 } 5770 5771 } 5772 5773 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) { 5774 assert(list != NULL, "list can't be null"); 5775 if (!list->is_empty()) { 5776 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag); 5777 _hrm.insert_list_into_free_list(list); 5778 } 5779 } 5780 5781 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) { 5782 _allocator->decrease_used(bytes); 5783 } 5784 5785 class G1ParCleanupCTTask : public AbstractGangTask { 5786 G1SATBCardTableModRefBS* _ct_bs; 5787 G1CollectedHeap* _g1h; 5788 HeapRegion* volatile _su_head; 5789 public: 5790 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs, 5791 G1CollectedHeap* g1h) : 5792 AbstractGangTask("G1 Par Cleanup CT Task"), 5793 _ct_bs(ct_bs), _g1h(g1h) { } 5794 5795 void work(uint worker_id) { 5796 HeapRegion* r; 5797 while (r = _g1h->pop_dirty_cards_region()) { 5798 clear_cards(r); 5799 } 5800 } 5801 5802 void clear_cards(HeapRegion* r) { 5803 // Cards of the survivors should have already been dirtied. 5804 if (!r->is_survivor()) { 5805 _ct_bs->clear(MemRegion(r->bottom(), r->end())); 5806 } 5807 } 5808 }; 5809 5810 #ifndef PRODUCT 5811 class G1VerifyCardTableCleanup: public HeapRegionClosure { 5812 G1CollectedHeap* _g1h; 5813 G1SATBCardTableModRefBS* _ct_bs; 5814 public: 5815 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs) 5816 : _g1h(g1h), _ct_bs(ct_bs) { } 5817 virtual bool doHeapRegion(HeapRegion* r) { 5818 if (r->is_survivor()) { 5819 _g1h->verify_dirty_region(r); 5820 } else { 5821 _g1h->verify_not_dirty_region(r); 5822 } 5823 return false; 5824 } 5825 }; 5826 5827 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) { 5828 // All of the region should be clean. 5829 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5830 MemRegion mr(hr->bottom(), hr->end()); 5831 ct_bs->verify_not_dirty_region(mr); 5832 } 5833 5834 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) { 5835 // We cannot guarantee that [bottom(),end()] is dirty. Threads 5836 // dirty allocated blocks as they allocate them. The thread that 5837 // retires each region and replaces it with a new one will do a 5838 // maximal allocation to fill in [pre_dummy_top(),end()] but will 5839 // not dirty that area (one less thing to have to do while holding 5840 // a lock). So we can only verify that [bottom(),pre_dummy_top()] 5841 // is dirty. 5842 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5843 MemRegion mr(hr->bottom(), hr->pre_dummy_top()); 5844 if (hr->is_young()) { 5845 ct_bs->verify_g1_young_region(mr); 5846 } else { 5847 ct_bs->verify_dirty_region(mr); 5848 } 5849 } 5850 5851 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) { 5852 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5853 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) { 5854 verify_dirty_region(hr); 5855 } 5856 } 5857 5858 void G1CollectedHeap::verify_dirty_young_regions() { 5859 verify_dirty_young_list(_young_list->first_region()); 5860 } 5861 5862 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap, 5863 HeapWord* tams, HeapWord* end) { 5864 guarantee(tams <= end, 5865 err_msg("tams: "PTR_FORMAT" end: "PTR_FORMAT, tams, end)); 5866 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end); 5867 if (result < end) { 5868 gclog_or_tty->cr(); 5869 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: "PTR_FORMAT, 5870 bitmap_name, result); 5871 gclog_or_tty->print_cr("## %s tams: "PTR_FORMAT" end: "PTR_FORMAT, 5872 bitmap_name, tams, end); 5873 return false; 5874 } 5875 return true; 5876 } 5877 5878 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) { 5879 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap(); 5880 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap(); 5881 5882 HeapWord* bottom = hr->bottom(); 5883 HeapWord* ptams = hr->prev_top_at_mark_start(); 5884 HeapWord* ntams = hr->next_top_at_mark_start(); 5885 HeapWord* end = hr->end(); 5886 5887 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end); 5888 5889 bool res_n = true; 5890 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window 5891 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap 5892 // if we happen to be in that state. 5893 if (mark_in_progress() || !_cmThread->in_progress()) { 5894 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end); 5895 } 5896 if (!res_p || !res_n) { 5897 gclog_or_tty->print_cr("#### Bitmap verification failed for "HR_FORMAT, 5898 HR_FORMAT_PARAMS(hr)); 5899 gclog_or_tty->print_cr("#### Caller: %s", caller); 5900 return false; 5901 } 5902 return true; 5903 } 5904 5905 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) { 5906 if (!G1VerifyBitmaps) return; 5907 5908 guarantee(verify_bitmaps(caller, hr), "bitmap verification"); 5909 } 5910 5911 class G1VerifyBitmapClosure : public HeapRegionClosure { 5912 private: 5913 const char* _caller; 5914 G1CollectedHeap* _g1h; 5915 bool _failures; 5916 5917 public: 5918 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) : 5919 _caller(caller), _g1h(g1h), _failures(false) { } 5920 5921 bool failures() { return _failures; } 5922 5923 virtual bool doHeapRegion(HeapRegion* hr) { 5924 if (hr->is_continues_humongous()) return false; 5925 5926 bool result = _g1h->verify_bitmaps(_caller, hr); 5927 if (!result) { 5928 _failures = true; 5929 } 5930 return false; 5931 } 5932 }; 5933 5934 void G1CollectedHeap::check_bitmaps(const char* caller) { 5935 if (!G1VerifyBitmaps) return; 5936 5937 G1VerifyBitmapClosure cl(caller, this); 5938 heap_region_iterate(&cl); 5939 guarantee(!cl.failures(), "bitmap verification"); 5940 } 5941 5942 class G1CheckCSetFastTableClosure : public HeapRegionClosure { 5943 private: 5944 bool _failures; 5945 public: 5946 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { } 5947 5948 virtual bool doHeapRegion(HeapRegion* hr) { 5949 uint i = hr->hrm_index(); 5950 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i); 5951 if (hr->is_humongous()) { 5952 if (hr->in_collection_set()) { 5953 gclog_or_tty->print_cr("\n## humongous region %u in CSet", i); 5954 _failures = true; 5955 return true; 5956 } 5957 if (cset_state.is_in_cset()) { 5958 gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i); 5959 _failures = true; 5960 return true; 5961 } 5962 if (hr->is_continues_humongous() && cset_state.is_humongous()) { 5963 gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i); 5964 _failures = true; 5965 return true; 5966 } 5967 } else { 5968 if (cset_state.is_humongous()) { 5969 gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i); 5970 _failures = true; 5971 return true; 5972 } 5973 if (hr->in_collection_set() != cset_state.is_in_cset()) { 5974 gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u", 5975 hr->in_collection_set(), cset_state.value(), i); 5976 _failures = true; 5977 return true; 5978 } 5979 if (cset_state.is_in_cset()) { 5980 if (hr->is_young() != (cset_state.is_young())) { 5981 gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u", 5982 hr->is_young(), cset_state.value(), i); 5983 _failures = true; 5984 return true; 5985 } 5986 if (hr->is_old() != (cset_state.is_old())) { 5987 gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u", 5988 hr->is_old(), cset_state.value(), i); 5989 _failures = true; 5990 return true; 5991 } 5992 } 5993 } 5994 return false; 5995 } 5996 5997 bool failures() const { return _failures; } 5998 }; 5999 6000 bool G1CollectedHeap::check_cset_fast_test() { 6001 G1CheckCSetFastTableClosure cl; 6002 _hrm.iterate(&cl); 6003 return !cl.failures(); 6004 } 6005 #endif // PRODUCT 6006 6007 void G1CollectedHeap::cleanUpCardTable() { 6008 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 6009 double start = os::elapsedTime(); 6010 6011 { 6012 // Iterate over the dirty cards region list. 6013 G1ParCleanupCTTask cleanup_task(ct_bs, this); 6014 6015 set_par_threads(); 6016 workers()->run_task(&cleanup_task); 6017 set_par_threads(0); 6018 #ifndef PRODUCT 6019 if (G1VerifyCTCleanup || VerifyAfterGC) { 6020 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs); 6021 heap_region_iterate(&cleanup_verifier); 6022 } 6023 #endif 6024 } 6025 6026 double elapsed = os::elapsedTime() - start; 6027 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0); 6028 } 6029 6030 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) { 6031 size_t pre_used = 0; 6032 FreeRegionList local_free_list("Local List for CSet Freeing"); 6033 6034 double young_time_ms = 0.0; 6035 double non_young_time_ms = 0.0; 6036 6037 // Since the collection set is a superset of the the young list, 6038 // all we need to do to clear the young list is clear its 6039 // head and length, and unlink any young regions in the code below 6040 _young_list->clear(); 6041 6042 G1CollectorPolicy* policy = g1_policy(); 6043 6044 double start_sec = os::elapsedTime(); 6045 bool non_young = true; 6046 6047 HeapRegion* cur = cs_head; 6048 int age_bound = -1; 6049 size_t rs_lengths = 0; 6050 6051 while (cur != NULL) { 6052 assert(!is_on_master_free_list(cur), "sanity"); 6053 if (non_young) { 6054 if (cur->is_young()) { 6055 double end_sec = os::elapsedTime(); 6056 double elapsed_ms = (end_sec - start_sec) * 1000.0; 6057 non_young_time_ms += elapsed_ms; 6058 6059 start_sec = os::elapsedTime(); 6060 non_young = false; 6061 } 6062 } else { 6063 if (!cur->is_young()) { 6064 double end_sec = os::elapsedTime(); 6065 double elapsed_ms = (end_sec - start_sec) * 1000.0; 6066 young_time_ms += elapsed_ms; 6067 6068 start_sec = os::elapsedTime(); 6069 non_young = true; 6070 } 6071 } 6072 6073 rs_lengths += cur->rem_set()->occupied_locked(); 6074 6075 HeapRegion* next = cur->next_in_collection_set(); 6076 assert(cur->in_collection_set(), "bad CS"); 6077 cur->set_next_in_collection_set(NULL); 6078 cur->set_in_collection_set(false); 6079 6080 if (cur->is_young()) { 6081 int index = cur->young_index_in_cset(); 6082 assert(index != -1, "invariant"); 6083 assert((uint) index < policy->young_cset_region_length(), "invariant"); 6084 size_t words_survived = _surviving_young_words[index]; 6085 cur->record_surv_words_in_group(words_survived); 6086 6087 // At this point the we have 'popped' cur from the collection set 6088 // (linked via next_in_collection_set()) but it is still in the 6089 // young list (linked via next_young_region()). Clear the 6090 // _next_young_region field. 6091 cur->set_next_young_region(NULL); 6092 } else { 6093 int index = cur->young_index_in_cset(); 6094 assert(index == -1, "invariant"); 6095 } 6096 6097 assert( (cur->is_young() && cur->young_index_in_cset() > -1) || 6098 (!cur->is_young() && cur->young_index_in_cset() == -1), 6099 "invariant" ); 6100 6101 if (!cur->evacuation_failed()) { 6102 MemRegion used_mr = cur->used_region(); 6103 6104 // And the region is empty. 6105 assert(!used_mr.is_empty(), "Should not have empty regions in a CS."); 6106 pre_used += cur->used(); 6107 free_region(cur, &local_free_list, false /* par */, true /* locked */); 6108 } else { 6109 cur->uninstall_surv_rate_group(); 6110 if (cur->is_young()) { 6111 cur->set_young_index_in_cset(-1); 6112 } 6113 cur->set_evacuation_failed(false); 6114 // The region is now considered to be old. 6115 cur->set_old(); 6116 _old_set.add(cur); 6117 evacuation_info.increment_collectionset_used_after(cur->used()); 6118 } 6119 cur = next; 6120 } 6121 6122 evacuation_info.set_regions_freed(local_free_list.length()); 6123 policy->record_max_rs_lengths(rs_lengths); 6124 policy->cset_regions_freed(); 6125 6126 double end_sec = os::elapsedTime(); 6127 double elapsed_ms = (end_sec - start_sec) * 1000.0; 6128 6129 if (non_young) { 6130 non_young_time_ms += elapsed_ms; 6131 } else { 6132 young_time_ms += elapsed_ms; 6133 } 6134 6135 prepend_to_freelist(&local_free_list); 6136 decrement_summary_bytes(pre_used); 6137 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms); 6138 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms); 6139 } 6140 6141 class G1FreeHumongousRegionClosure : public HeapRegionClosure { 6142 private: 6143 FreeRegionList* _free_region_list; 6144 HeapRegionSet* _proxy_set; 6145 HeapRegionSetCount _humongous_regions_removed; 6146 size_t _freed_bytes; 6147 public: 6148 6149 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) : 6150 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) { 6151 } 6152 6153 virtual bool doHeapRegion(HeapRegion* r) { 6154 if (!r->is_starts_humongous()) { 6155 return false; 6156 } 6157 6158 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 6159 6160 oop obj = (oop)r->bottom(); 6161 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap(); 6162 6163 // The following checks whether the humongous object is live are sufficient. 6164 // The main additional check (in addition to having a reference from the roots 6165 // or the young gen) is whether the humongous object has a remembered set entry. 6166 // 6167 // A humongous object cannot be live if there is no remembered set for it 6168 // because: 6169 // - there can be no references from within humongous starts regions referencing 6170 // the object because we never allocate other objects into them. 6171 // (I.e. there are no intra-region references that may be missed by the 6172 // remembered set) 6173 // - as soon there is a remembered set entry to the humongous starts region 6174 // (i.e. it has "escaped" to an old object) this remembered set entry will stay 6175 // until the end of a concurrent mark. 6176 // 6177 // It is not required to check whether the object has been found dead by marking 6178 // or not, in fact it would prevent reclamation within a concurrent cycle, as 6179 // all objects allocated during that time are considered live. 6180 // SATB marking is even more conservative than the remembered set. 6181 // So if at this point in the collection there is no remembered set entry, 6182 // nobody has a reference to it. 6183 // At the start of collection we flush all refinement logs, and remembered sets 6184 // are completely up-to-date wrt to references to the humongous object. 6185 // 6186 // Other implementation considerations: 6187 // - never consider object arrays at this time because they would pose 6188 // considerable effort for cleaning up the the remembered sets. This is 6189 // required because stale remembered sets might reference locations that 6190 // are currently allocated into. 6191 uint region_idx = r->hrm_index(); 6192 if (g1h->humongous_is_live(region_idx) || 6193 g1h->humongous_region_is_always_live(region_idx)) { 6194 6195 if (G1TraceEagerReclaimHumongousObjects) { 6196 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", 6197 region_idx, 6198 obj->size()*HeapWordSize, 6199 r->bottom(), 6200 r->region_num(), 6201 r->rem_set()->occupied(), 6202 r->rem_set()->strong_code_roots_list_length(), 6203 next_bitmap->isMarked(r->bottom()), 6204 g1h->humongous_is_live(region_idx), 6205 obj->is_objArray() 6206 ); 6207 } 6208 6209 return false; 6210 } 6211 6212 guarantee(!obj->is_objArray(), 6213 err_msg("Eagerly reclaiming object arrays is not supported, but the object "PTR_FORMAT" is.", 6214 r->bottom())); 6215 6216 if (G1TraceEagerReclaimHumongousObjects) { 6217 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", 6218 region_idx, 6219 obj->size()*HeapWordSize, 6220 r->bottom(), 6221 r->region_num(), 6222 r->rem_set()->occupied(), 6223 r->rem_set()->strong_code_roots_list_length(), 6224 next_bitmap->isMarked(r->bottom()), 6225 g1h->humongous_is_live(region_idx), 6226 obj->is_objArray() 6227 ); 6228 } 6229 // Need to clear mark bit of the humongous object if already set. 6230 if (next_bitmap->isMarked(r->bottom())) { 6231 next_bitmap->clear(r->bottom()); 6232 } 6233 _freed_bytes += r->used(); 6234 r->set_containing_set(NULL); 6235 _humongous_regions_removed.increment(1u, r->capacity()); 6236 g1h->free_humongous_region(r, _free_region_list, false); 6237 6238 return false; 6239 } 6240 6241 HeapRegionSetCount& humongous_free_count() { 6242 return _humongous_regions_removed; 6243 } 6244 6245 size_t bytes_freed() const { 6246 return _freed_bytes; 6247 } 6248 6249 size_t humongous_reclaimed() const { 6250 return _humongous_regions_removed.length(); 6251 } 6252 }; 6253 6254 void G1CollectedHeap::eagerly_reclaim_humongous_regions() { 6255 assert_at_safepoint(true); 6256 6257 if (!G1EagerReclaimHumongousObjects || 6258 (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) { 6259 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0); 6260 return; 6261 } 6262 6263 double start_time = os::elapsedTime(); 6264 6265 FreeRegionList local_cleanup_list("Local Humongous Cleanup List"); 6266 6267 G1FreeHumongousRegionClosure cl(&local_cleanup_list); 6268 heap_region_iterate(&cl); 6269 6270 HeapRegionSetCount empty_set; 6271 remove_from_old_sets(empty_set, cl.humongous_free_count()); 6272 6273 G1HRPrinter* hr_printer = _g1h->hr_printer(); 6274 if (hr_printer->is_active()) { 6275 FreeRegionListIterator iter(&local_cleanup_list); 6276 while (iter.more_available()) { 6277 HeapRegion* hr = iter.get_next(); 6278 hr_printer->cleanup(hr); 6279 } 6280 } 6281 6282 prepend_to_freelist(&local_cleanup_list); 6283 decrement_summary_bytes(cl.bytes_freed()); 6284 6285 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0, 6286 cl.humongous_reclaimed()); 6287 } 6288 6289 // This routine is similar to the above but does not record 6290 // any policy statistics or update free lists; we are abandoning 6291 // the current incremental collection set in preparation of a 6292 // full collection. After the full GC we will start to build up 6293 // the incremental collection set again. 6294 // This is only called when we're doing a full collection 6295 // and is immediately followed by the tearing down of the young list. 6296 6297 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) { 6298 HeapRegion* cur = cs_head; 6299 6300 while (cur != NULL) { 6301 HeapRegion* next = cur->next_in_collection_set(); 6302 assert(cur->in_collection_set(), "bad CS"); 6303 cur->set_next_in_collection_set(NULL); 6304 cur->set_in_collection_set(false); 6305 cur->set_young_index_in_cset(-1); 6306 cur = next; 6307 } 6308 } 6309 6310 void G1CollectedHeap::set_free_regions_coming() { 6311 if (G1ConcRegionFreeingVerbose) { 6312 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " 6313 "setting free regions coming"); 6314 } 6315 6316 assert(!free_regions_coming(), "pre-condition"); 6317 _free_regions_coming = true; 6318 } 6319 6320 void G1CollectedHeap::reset_free_regions_coming() { 6321 assert(free_regions_coming(), "pre-condition"); 6322 6323 { 6324 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6325 _free_regions_coming = false; 6326 SecondaryFreeList_lock->notify_all(); 6327 } 6328 6329 if (G1ConcRegionFreeingVerbose) { 6330 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " 6331 "reset free regions coming"); 6332 } 6333 } 6334 6335 void G1CollectedHeap::wait_while_free_regions_coming() { 6336 // Most of the time we won't have to wait, so let's do a quick test 6337 // first before we take the lock. 6338 if (!free_regions_coming()) { 6339 return; 6340 } 6341 6342 if (G1ConcRegionFreeingVerbose) { 6343 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " 6344 "waiting for free regions"); 6345 } 6346 6347 { 6348 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6349 while (free_regions_coming()) { 6350 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 6351 } 6352 } 6353 6354 if (G1ConcRegionFreeingVerbose) { 6355 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " 6356 "done waiting for free regions"); 6357 } 6358 } 6359 6360 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 6361 assert(heap_lock_held_for_gc(), 6362 "the heap lock should already be held by or for this thread"); 6363 _young_list->push_region(hr); 6364 } 6365 6366 class NoYoungRegionsClosure: public HeapRegionClosure { 6367 private: 6368 bool _success; 6369 public: 6370 NoYoungRegionsClosure() : _success(true) { } 6371 bool doHeapRegion(HeapRegion* r) { 6372 if (r->is_young()) { 6373 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young", 6374 r->bottom(), r->end()); 6375 _success = false; 6376 } 6377 return false; 6378 } 6379 bool success() { return _success; } 6380 }; 6381 6382 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) { 6383 bool ret = _young_list->check_list_empty(check_sample); 6384 6385 if (check_heap) { 6386 NoYoungRegionsClosure closure; 6387 heap_region_iterate(&closure); 6388 ret = ret && closure.success(); 6389 } 6390 6391 return ret; 6392 } 6393 6394 class TearDownRegionSetsClosure : public HeapRegionClosure { 6395 private: 6396 HeapRegionSet *_old_set; 6397 6398 public: 6399 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { } 6400 6401 bool doHeapRegion(HeapRegion* r) { 6402 if (r->is_old()) { 6403 _old_set->remove(r); 6404 } else { 6405 // We ignore free regions, we'll empty the free list afterwards. 6406 // We ignore young regions, we'll empty the young list afterwards. 6407 // We ignore humongous regions, we're not tearing down the 6408 // humongous regions set. 6409 assert(r->is_free() || r->is_young() || r->is_humongous(), 6410 "it cannot be another type"); 6411 } 6412 return false; 6413 } 6414 6415 ~TearDownRegionSetsClosure() { 6416 assert(_old_set->is_empty(), "post-condition"); 6417 } 6418 }; 6419 6420 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) { 6421 assert_at_safepoint(true /* should_be_vm_thread */); 6422 6423 if (!free_list_only) { 6424 TearDownRegionSetsClosure cl(&_old_set); 6425 heap_region_iterate(&cl); 6426 6427 // Note that emptying the _young_list is postponed and instead done as 6428 // the first step when rebuilding the regions sets again. The reason for 6429 // this is that during a full GC string deduplication needs to know if 6430 // a collected region was young or old when the full GC was initiated. 6431 } 6432 _hrm.remove_all_free_regions(); 6433 } 6434 6435 class RebuildRegionSetsClosure : public HeapRegionClosure { 6436 private: 6437 bool _free_list_only; 6438 HeapRegionSet* _old_set; 6439 HeapRegionManager* _hrm; 6440 size_t _total_used; 6441 6442 public: 6443 RebuildRegionSetsClosure(bool free_list_only, 6444 HeapRegionSet* old_set, HeapRegionManager* hrm) : 6445 _free_list_only(free_list_only), 6446 _old_set(old_set), _hrm(hrm), _total_used(0) { 6447 assert(_hrm->num_free_regions() == 0, "pre-condition"); 6448 if (!free_list_only) { 6449 assert(_old_set->is_empty(), "pre-condition"); 6450 } 6451 } 6452 6453 bool doHeapRegion(HeapRegion* r) { 6454 if (r->is_continues_humongous()) { 6455 return false; 6456 } 6457 6458 if (r->is_empty()) { 6459 // Add free regions to the free list 6460 r->set_free(); 6461 r->set_allocation_context(AllocationContext::system()); 6462 _hrm->insert_into_free_list(r); 6463 } else if (!_free_list_only) { 6464 assert(!r->is_young(), "we should not come across young regions"); 6465 6466 if (r->is_humongous()) { 6467 // We ignore humongous regions, we left the humongous set unchanged 6468 } else { 6469 // Objects that were compacted would have ended up on regions 6470 // that were previously old or free. 6471 assert(r->is_free() || r->is_old(), "invariant"); 6472 // We now consider them old, so register as such. 6473 r->set_old(); 6474 _old_set->add(r); 6475 } 6476 _total_used += r->used(); 6477 } 6478 6479 return false; 6480 } 6481 6482 size_t total_used() { 6483 return _total_used; 6484 } 6485 }; 6486 6487 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { 6488 assert_at_safepoint(true /* should_be_vm_thread */); 6489 6490 if (!free_list_only) { 6491 _young_list->empty_list(); 6492 } 6493 6494 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm); 6495 heap_region_iterate(&cl); 6496 6497 if (!free_list_only) { 6498 _allocator->set_used(cl.total_used()); 6499 } 6500 assert(_allocator->used_unlocked() == recalculate_used(), 6501 err_msg("inconsistent _allocator->used_unlocked(), " 6502 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT, 6503 _allocator->used_unlocked(), recalculate_used())); 6504 } 6505 6506 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) { 6507 _refine_cte_cl->set_concurrent(concurrent); 6508 } 6509 6510 bool G1CollectedHeap::is_in_closed_subset(const void* p) const { 6511 HeapRegion* hr = heap_region_containing(p); 6512 return hr->is_in(p); 6513 } 6514 6515 // Methods for the mutator alloc region 6516 6517 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 6518 bool force) { 6519 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6520 assert(!force || g1_policy()->can_expand_young_list(), 6521 "if force is true we should be able to expand the young list"); 6522 bool young_list_full = g1_policy()->is_young_list_full(); 6523 if (force || !young_list_full) { 6524 HeapRegion* new_alloc_region = new_region(word_size, 6525 false /* is_old */, 6526 false /* do_expand */); 6527 if (new_alloc_region != NULL) { 6528 set_region_short_lived_locked(new_alloc_region); 6529 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full); 6530 check_bitmaps("Mutator Region Allocation", new_alloc_region); 6531 return new_alloc_region; 6532 } 6533 } 6534 return NULL; 6535 } 6536 6537 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 6538 size_t allocated_bytes) { 6539 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6540 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden"); 6541 6542 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region); 6543 _allocator->increase_used(allocated_bytes); 6544 _hr_printer.retire(alloc_region); 6545 // We update the eden sizes here, when the region is retired, 6546 // instead of when it's allocated, since this is the point that its 6547 // used space has been recored in _summary_bytes_used. 6548 g1mm()->update_eden_size(); 6549 } 6550 6551 void G1CollectedHeap::set_par_threads() { 6552 // Don't change the number of workers. Use the value previously set 6553 // in the workgroup. 6554 uint n_workers = workers()->active_workers(); 6555 assert(UseDynamicNumberOfGCThreads || 6556 n_workers == workers()->total_workers(), 6557 "Otherwise should be using the total number of workers"); 6558 if (n_workers == 0) { 6559 assert(false, "Should have been set in prior evacuation pause."); 6560 n_workers = ParallelGCThreads; 6561 workers()->set_active_workers(n_workers); 6562 } 6563 set_par_threads(n_workers); 6564 } 6565 6566 // Methods for the GC alloc regions 6567 6568 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, 6569 uint count, 6570 InCSetState dest) { 6571 assert(FreeList_lock->owned_by_self(), "pre-condition"); 6572 6573 if (count < g1_policy()->max_regions(dest)) { 6574 const bool is_survivor = (dest.is_young()); 6575 HeapRegion* new_alloc_region = new_region(word_size, 6576 !is_survivor, 6577 true /* do_expand */); 6578 if (new_alloc_region != NULL) { 6579 // We really only need to do this for old regions given that we 6580 // should never scan survivors. But it doesn't hurt to do it 6581 // for survivors too. 6582 new_alloc_region->record_timestamp(); 6583 if (is_survivor) { 6584 new_alloc_region->set_survivor(); 6585 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor); 6586 check_bitmaps("Survivor Region Allocation", new_alloc_region); 6587 } else { 6588 new_alloc_region->set_old(); 6589 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old); 6590 check_bitmaps("Old Region Allocation", new_alloc_region); 6591 } 6592 bool during_im = g1_policy()->during_initial_mark_pause(); 6593 new_alloc_region->note_start_of_copying(during_im); 6594 return new_alloc_region; 6595 } 6596 } 6597 return NULL; 6598 } 6599 6600 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 6601 size_t allocated_bytes, 6602 InCSetState dest) { 6603 bool during_im = g1_policy()->during_initial_mark_pause(); 6604 alloc_region->note_end_of_copying(during_im); 6605 g1_policy()->record_bytes_copied_during_gc(allocated_bytes); 6606 if (dest.is_young()) { 6607 young_list()->add_survivor_region(alloc_region); 6608 } else { 6609 _old_set.add(alloc_region); 6610 } 6611 _hr_printer.retire(alloc_region); 6612 } 6613 6614 // Heap region set verification 6615 6616 class VerifyRegionListsClosure : public HeapRegionClosure { 6617 private: 6618 HeapRegionSet* _old_set; 6619 HeapRegionSet* _humongous_set; 6620 HeapRegionManager* _hrm; 6621 6622 public: 6623 HeapRegionSetCount _old_count; 6624 HeapRegionSetCount _humongous_count; 6625 HeapRegionSetCount _free_count; 6626 6627 VerifyRegionListsClosure(HeapRegionSet* old_set, 6628 HeapRegionSet* humongous_set, 6629 HeapRegionManager* hrm) : 6630 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm), 6631 _old_count(), _humongous_count(), _free_count(){ } 6632 6633 bool doHeapRegion(HeapRegion* hr) { 6634 if (hr->is_continues_humongous()) { 6635 return false; 6636 } 6637 6638 if (hr->is_young()) { 6639 // TODO 6640 } else if (hr->is_starts_humongous()) { 6641 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrm_index())); 6642 _humongous_count.increment(1u, hr->capacity()); 6643 } else if (hr->is_empty()) { 6644 assert(_hrm->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrm_index())); 6645 _free_count.increment(1u, hr->capacity()); 6646 } else if (hr->is_old()) { 6647 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrm_index())); 6648 _old_count.increment(1u, hr->capacity()); 6649 } else { 6650 ShouldNotReachHere(); 6651 } 6652 return false; 6653 } 6654 6655 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) { 6656 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length())); 6657 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6658 old_set->total_capacity_bytes(), _old_count.capacity())); 6659 6660 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length())); 6661 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6662 humongous_set->total_capacity_bytes(), _humongous_count.capacity())); 6663 6664 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())); 6665 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6666 free_list->total_capacity_bytes(), _free_count.capacity())); 6667 } 6668 }; 6669 6670 void G1CollectedHeap::verify_region_sets() { 6671 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6672 6673 // First, check the explicit lists. 6674 _hrm.verify(); 6675 { 6676 // Given that a concurrent operation might be adding regions to 6677 // the secondary free list we have to take the lock before 6678 // verifying it. 6679 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6680 _secondary_free_list.verify_list(); 6681 } 6682 6683 // If a concurrent region freeing operation is in progress it will 6684 // be difficult to correctly attributed any free regions we come 6685 // across to the correct free list given that they might belong to 6686 // one of several (free_list, secondary_free_list, any local lists, 6687 // etc.). So, if that's the case we will skip the rest of the 6688 // verification operation. Alternatively, waiting for the concurrent 6689 // operation to complete will have a non-trivial effect on the GC's 6690 // operation (no concurrent operation will last longer than the 6691 // interval between two calls to verification) and it might hide 6692 // any issues that we would like to catch during testing. 6693 if (free_regions_coming()) { 6694 return; 6695 } 6696 6697 // Make sure we append the secondary_free_list on the free_list so 6698 // that all free regions we will come across can be safely 6699 // attributed to the free_list. 6700 append_secondary_free_list_if_not_empty_with_lock(); 6701 6702 // Finally, make sure that the region accounting in the lists is 6703 // consistent with what we see in the heap. 6704 6705 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm); 6706 heap_region_iterate(&cl); 6707 cl.verify_counts(&_old_set, &_humongous_set, &_hrm); 6708 } 6709 6710 // Optimized nmethod scanning 6711 6712 class RegisterNMethodOopClosure: public OopClosure { 6713 G1CollectedHeap* _g1h; 6714 nmethod* _nm; 6715 6716 template <class T> void do_oop_work(T* p) { 6717 T heap_oop = oopDesc::load_heap_oop(p); 6718 if (!oopDesc::is_null(heap_oop)) { 6719 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 6720 HeapRegion* hr = _g1h->heap_region_containing(obj); 6721 assert(!hr->is_continues_humongous(), 6722 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT 6723 " starting at "HR_FORMAT, 6724 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()))); 6725 6726 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries. 6727 hr->add_strong_code_root_locked(_nm); 6728 } 6729 } 6730 6731 public: 6732 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 6733 _g1h(g1h), _nm(nm) {} 6734 6735 void do_oop(oop* p) { do_oop_work(p); } 6736 void do_oop(narrowOop* p) { do_oop_work(p); } 6737 }; 6738 6739 class UnregisterNMethodOopClosure: public OopClosure { 6740 G1CollectedHeap* _g1h; 6741 nmethod* _nm; 6742 6743 template <class T> void do_oop_work(T* p) { 6744 T heap_oop = oopDesc::load_heap_oop(p); 6745 if (!oopDesc::is_null(heap_oop)) { 6746 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 6747 HeapRegion* hr = _g1h->heap_region_containing(obj); 6748 assert(!hr->is_continues_humongous(), 6749 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT 6750 " starting at "HR_FORMAT, 6751 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()))); 6752 6753 hr->remove_strong_code_root(_nm); 6754 } 6755 } 6756 6757 public: 6758 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 6759 _g1h(g1h), _nm(nm) {} 6760 6761 void do_oop(oop* p) { do_oop_work(p); } 6762 void do_oop(narrowOop* p) { do_oop_work(p); } 6763 }; 6764 6765 void G1CollectedHeap::register_nmethod(nmethod* nm) { 6766 CollectedHeap::register_nmethod(nm); 6767 6768 guarantee(nm != NULL, "sanity"); 6769 RegisterNMethodOopClosure reg_cl(this, nm); 6770 nm->oops_do(®_cl); 6771 } 6772 6773 void G1CollectedHeap::unregister_nmethod(nmethod* nm) { 6774 CollectedHeap::unregister_nmethod(nm); 6775 6776 guarantee(nm != NULL, "sanity"); 6777 UnregisterNMethodOopClosure reg_cl(this, nm); 6778 nm->oops_do(®_cl, true); 6779 } 6780 6781 void G1CollectedHeap::purge_code_root_memory() { 6782 double purge_start = os::elapsedTime(); 6783 G1CodeRootSet::purge(); 6784 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0; 6785 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms); 6786 } 6787 6788 class RebuildStrongCodeRootClosure: public CodeBlobClosure { 6789 G1CollectedHeap* _g1h; 6790 6791 public: 6792 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) : 6793 _g1h(g1h) {} 6794 6795 void do_code_blob(CodeBlob* cb) { 6796 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL; 6797 if (nm == NULL) { 6798 return; 6799 } 6800 6801 if (ScavengeRootsInCode) { 6802 _g1h->register_nmethod(nm); 6803 } 6804 } 6805 }; 6806 6807 void G1CollectedHeap::rebuild_strong_code_roots() { 6808 RebuildStrongCodeRootClosure blob_cl(this); 6809 CodeCache::blobs_do(&blob_cl); 6810 }