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 double start = os::elapsedTime(); 1233 g1_policy()->record_full_collection_start(); 1234 1235 // Note: When we have a more flexible GC logging framework that 1236 // allows us to add optional attributes to a GC log record we 1237 // could consider timing and reporting how long we wait in the 1238 // following two methods. 1239 wait_while_free_regions_coming(); 1240 // If we start the compaction before the CM threads finish 1241 // scanning the root regions we might trip them over as we'll 1242 // be moving objects / updating references. So let's wait until 1243 // they are done. By telling them to abort, they should complete 1244 // early. 1245 _cm->root_regions()->abort(); 1246 _cm->root_regions()->wait_until_scan_finished(); 1247 append_secondary_free_list_if_not_empty_with_lock(); 1248 1249 gc_prologue(true); 1250 increment_total_collections(true /* full gc */); 1251 increment_old_marking_cycles_started(); 1252 1253 assert(used() == recalculate_used(), "Should be equal"); 1254 1255 verify_before_gc(); 1256 1257 check_bitmaps("Full GC Start"); 1258 pre_full_gc_dump(gc_timer); 1259 1260 COMPILER2_PRESENT(DerivedPointerTable::clear()); 1261 1262 // Disable discovery and empty the discovered lists 1263 // for the CM ref processor. 1264 ref_processor_cm()->disable_discovery(); 1265 ref_processor_cm()->abandon_partial_discovery(); 1266 ref_processor_cm()->verify_no_references_recorded(); 1267 1268 // Abandon current iterations of concurrent marking and concurrent 1269 // refinement, if any are in progress. We have to do this before 1270 // wait_until_scan_finished() below. 1271 concurrent_mark()->abort(); 1272 1273 // Make sure we'll choose a new allocation region afterwards. 1274 _allocator->release_mutator_alloc_region(); 1275 _allocator->abandon_gc_alloc_regions(); 1276 g1_rem_set()->cleanupHRRS(); 1277 1278 // We should call this after we retire any currently active alloc 1279 // regions so that all the ALLOC / RETIRE events are generated 1280 // before the start GC event. 1281 _hr_printer.start_gc(true /* full */, (size_t) total_collections()); 1282 1283 // We may have added regions to the current incremental collection 1284 // set between the last GC or pause and now. We need to clear the 1285 // incremental collection set and then start rebuilding it afresh 1286 // after this full GC. 1287 abandon_collection_set(g1_policy()->inc_cset_head()); 1288 g1_policy()->clear_incremental_cset(); 1289 g1_policy()->stop_incremental_cset_building(); 1290 1291 tear_down_region_sets(false /* free_list_only */); 1292 g1_policy()->set_gcs_are_young(true); 1293 1294 // See the comments in g1CollectedHeap.hpp and 1295 // G1CollectedHeap::ref_processing_init() about 1296 // how reference processing currently works in G1. 1297 1298 // Temporarily make discovery by the STW ref processor single threaded (non-MT). 1299 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false); 1300 1301 // Temporarily clear the STW ref processor's _is_alive_non_header field. 1302 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL); 1303 1304 ref_processor_stw()->enable_discovery(); 1305 ref_processor_stw()->setup_policy(do_clear_all_soft_refs); 1306 1307 // Do collection work 1308 { 1309 HandleMark hm; // Discard invalid handles created during gc 1310 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs); 1311 } 1312 1313 assert(num_free_regions() == 0, "we should not have added any free regions"); 1314 rebuild_region_sets(false /* free_list_only */); 1315 1316 // Enqueue any discovered reference objects that have 1317 // not been removed from the discovered lists. 1318 ref_processor_stw()->enqueue_discovered_references(); 1319 1320 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 1321 1322 MemoryService::track_memory_usage(); 1323 1324 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 1325 ref_processor_stw()->verify_no_references_recorded(); 1326 1327 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 1328 ClassLoaderDataGraph::purge(); 1329 MetaspaceAux::verify_metrics(); 1330 1331 // Note: since we've just done a full GC, concurrent 1332 // marking is no longer active. Therefore we need not 1333 // re-enable reference discovery for the CM ref processor. 1334 // That will be done at the start of the next marking cycle. 1335 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition"); 1336 ref_processor_cm()->verify_no_references_recorded(); 1337 1338 reset_gc_time_stamp(); 1339 // Since everything potentially moved, we will clear all remembered 1340 // sets, and clear all cards. Later we will rebuild remembered 1341 // sets. We will also reset the GC time stamps of the regions. 1342 clear_rsets_post_compaction(); 1343 check_gc_time_stamps(); 1344 1345 // Resize the heap if necessary. 1346 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size); 1347 1348 if (_hr_printer.is_active()) { 1349 // We should do this after we potentially resize the heap so 1350 // that all the COMMIT / UNCOMMIT events are generated before 1351 // the end GC event. 1352 1353 print_hrm_post_compaction(); 1354 _hr_printer.end_gc(true /* full */, (size_t) total_collections()); 1355 } 1356 1357 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 1358 if (hot_card_cache->use_cache()) { 1359 hot_card_cache->reset_card_counts(); 1360 hot_card_cache->reset_hot_cache(); 1361 } 1362 1363 // Rebuild remembered sets of all regions. 1364 uint n_workers = 1365 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 1366 workers()->active_workers(), 1367 Threads::number_of_non_daemon_threads()); 1368 assert(UseDynamicNumberOfGCThreads || 1369 n_workers == workers()->total_workers(), 1370 "If not dynamic should be using all the workers"); 1371 workers()->set_active_workers(n_workers); 1372 // Set parallel threads in the heap (_n_par_threads) only 1373 // before a parallel phase and always reset it to 0 after 1374 // the phase so that the number of parallel threads does 1375 // no get carried forward to a serial phase where there 1376 // may be code that is "possibly_parallel". 1377 set_par_threads(n_workers); 1378 1379 ParRebuildRSTask rebuild_rs_task(this); 1380 assert(UseDynamicNumberOfGCThreads || 1381 workers()->active_workers() == workers()->total_workers(), 1382 "Unless dynamic should use total workers"); 1383 // Use the most recent number of active workers 1384 assert(workers()->active_workers() > 0, 1385 "Active workers not properly set"); 1386 set_par_threads(workers()->active_workers()); 1387 workers()->run_task(&rebuild_rs_task); 1388 set_par_threads(0); 1389 1390 // Rebuild the strong code root lists for each region 1391 rebuild_strong_code_roots(); 1392 1393 if (true) { // FIXME 1394 MetaspaceGC::compute_new_size(); 1395 } 1396 1397 #ifdef TRACESPINNING 1398 ParallelTaskTerminator::print_termination_counts(); 1399 #endif 1400 1401 // Discard all rset updates 1402 JavaThread::dirty_card_queue_set().abandon_logs(); 1403 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty"); 1404 1405 _young_list->reset_sampled_info(); 1406 // At this point there should be no regions in the 1407 // entire heap tagged as young. 1408 assert(check_young_list_empty(true /* check_heap */), 1409 "young list should be empty at this point"); 1410 1411 // Update the number of full collections that have been completed. 1412 increment_old_marking_cycles_completed(false /* concurrent */); 1413 1414 _hrm.verify_optional(); 1415 verify_region_sets_optional(); 1416 1417 verify_after_gc(); 1418 1419 // Clear the previous marking bitmap, if needed for bitmap verification. 1420 // Note we cannot do this when we clear the next marking bitmap in 1421 // ConcurrentMark::abort() above since VerifyDuringGC verifies the 1422 // objects marked during a full GC against the previous bitmap. 1423 // But we need to clear it before calling check_bitmaps below since 1424 // the full GC has compacted objects and updated TAMS but not updated 1425 // the prev bitmap. 1426 if (G1VerifyBitmaps) { 1427 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll(); 1428 } 1429 check_bitmaps("Full GC End"); 1430 1431 // Start a new incremental collection set for the next pause 1432 assert(g1_policy()->collection_set() == NULL, "must be"); 1433 g1_policy()->start_incremental_cset_building(); 1434 1435 clear_cset_fast_test(); 1436 1437 _allocator->init_mutator_alloc_region(); 1438 1439 double end = os::elapsedTime(); 1440 g1_policy()->record_full_collection_end(); 1441 1442 if (G1Log::fine()) { 1443 g1_policy()->print_heap_transition(); 1444 } 1445 1446 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 1447 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 1448 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 1449 // before any GC notifications are raised. 1450 g1mm()->update_sizes(); 1451 1452 gc_epilogue(true); 1453 } 1454 1455 if (G1Log::finer()) { 1456 g1_policy()->print_detailed_heap_transition(true /* full */); 1457 } 1458 1459 print_heap_after_gc(); 1460 trace_heap_after_gc(gc_tracer); 1461 1462 post_full_gc_dump(gc_timer); 1463 1464 gc_timer->register_gc_end(); 1465 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions()); 1466 } 1467 1468 return true; 1469 } 1470 1471 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) { 1472 // do_collection() will return whether it succeeded in performing 1473 // the GC. Currently, there is no facility on the 1474 // do_full_collection() API to notify the caller than the collection 1475 // did not succeed (e.g., because it was locked out by the GC 1476 // locker). So, right now, we'll ignore the return value. 1477 bool dummy = do_collection(true, /* explicit_gc */ 1478 clear_all_soft_refs, 1479 0 /* word_size */); 1480 } 1481 1482 // This code is mostly copied from TenuredGeneration. 1483 void 1484 G1CollectedHeap:: 1485 resize_if_necessary_after_full_collection(size_t word_size) { 1486 // Include the current allocation, if any, and bytes that will be 1487 // pre-allocated to support collections, as "used". 1488 const size_t used_after_gc = used(); 1489 const size_t capacity_after_gc = capacity(); 1490 const size_t free_after_gc = capacity_after_gc - used_after_gc; 1491 1492 // This is enforced in arguments.cpp. 1493 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, 1494 "otherwise the code below doesn't make sense"); 1495 1496 // We don't have floating point command-line arguments 1497 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0; 1498 const double maximum_used_percentage = 1.0 - minimum_free_percentage; 1499 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0; 1500 const double minimum_used_percentage = 1.0 - maximum_free_percentage; 1501 1502 const size_t min_heap_size = collector_policy()->min_heap_byte_size(); 1503 const size_t max_heap_size = collector_policy()->max_heap_byte_size(); 1504 1505 // We have to be careful here as these two calculations can overflow 1506 // 32-bit size_t's. 1507 double used_after_gc_d = (double) used_after_gc; 1508 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage; 1509 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage; 1510 1511 // Let's make sure that they are both under the max heap size, which 1512 // by default will make them fit into a size_t. 1513 double desired_capacity_upper_bound = (double) max_heap_size; 1514 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d, 1515 desired_capacity_upper_bound); 1516 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d, 1517 desired_capacity_upper_bound); 1518 1519 // We can now safely turn them into size_t's. 1520 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d; 1521 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d; 1522 1523 // This assert only makes sense here, before we adjust them 1524 // with respect to the min and max heap size. 1525 assert(minimum_desired_capacity <= maximum_desired_capacity, 1526 err_msg("minimum_desired_capacity = "SIZE_FORMAT", " 1527 "maximum_desired_capacity = "SIZE_FORMAT, 1528 minimum_desired_capacity, maximum_desired_capacity)); 1529 1530 // Should not be greater than the heap max size. No need to adjust 1531 // it with respect to the heap min size as it's a lower bound (i.e., 1532 // we'll try to make the capacity larger than it, not smaller). 1533 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size); 1534 // Should not be less than the heap min size. No need to adjust it 1535 // with respect to the heap max size as it's an upper bound (i.e., 1536 // we'll try to make the capacity smaller than it, not greater). 1537 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size); 1538 1539 if (capacity_after_gc < minimum_desired_capacity) { 1540 // Don't expand unless it's significant 1541 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc; 1542 ergo_verbose4(ErgoHeapSizing, 1543 "attempt heap expansion", 1544 ergo_format_reason("capacity lower than " 1545 "min desired capacity after Full GC") 1546 ergo_format_byte("capacity") 1547 ergo_format_byte("occupancy") 1548 ergo_format_byte_perc("min desired capacity"), 1549 capacity_after_gc, used_after_gc, 1550 minimum_desired_capacity, (double) MinHeapFreeRatio); 1551 expand(expand_bytes); 1552 1553 // No expansion, now see if we want to shrink 1554 } else if (capacity_after_gc > maximum_desired_capacity) { 1555 // Capacity too large, compute shrinking size 1556 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity; 1557 ergo_verbose4(ErgoHeapSizing, 1558 "attempt heap shrinking", 1559 ergo_format_reason("capacity higher than " 1560 "max desired capacity after Full GC") 1561 ergo_format_byte("capacity") 1562 ergo_format_byte("occupancy") 1563 ergo_format_byte_perc("max desired capacity"), 1564 capacity_after_gc, used_after_gc, 1565 maximum_desired_capacity, (double) MaxHeapFreeRatio); 1566 shrink(shrink_bytes); 1567 } 1568 } 1569 1570 1571 HeapWord* 1572 G1CollectedHeap::satisfy_failed_allocation(size_t word_size, 1573 AllocationContext_t context, 1574 bool* succeeded) { 1575 assert_at_safepoint(true /* should_be_vm_thread */); 1576 1577 *succeeded = true; 1578 // Let's attempt the allocation first. 1579 HeapWord* result = 1580 attempt_allocation_at_safepoint(word_size, 1581 context, 1582 false /* expect_null_mutator_alloc_region */); 1583 if (result != NULL) { 1584 assert(*succeeded, "sanity"); 1585 return result; 1586 } 1587 1588 // In a G1 heap, we're supposed to keep allocation from failing by 1589 // incremental pauses. Therefore, at least for now, we'll favor 1590 // expansion over collection. (This might change in the future if we can 1591 // do something smarter than full collection to satisfy a failed alloc.) 1592 result = expand_and_allocate(word_size, context); 1593 if (result != NULL) { 1594 assert(*succeeded, "sanity"); 1595 return result; 1596 } 1597 1598 // Expansion didn't work, we'll try to do a Full GC. 1599 bool gc_succeeded = do_collection(false, /* explicit_gc */ 1600 false, /* clear_all_soft_refs */ 1601 word_size); 1602 if (!gc_succeeded) { 1603 *succeeded = false; 1604 return NULL; 1605 } 1606 1607 // Retry the allocation 1608 result = attempt_allocation_at_safepoint(word_size, 1609 context, 1610 true /* expect_null_mutator_alloc_region */); 1611 if (result != NULL) { 1612 assert(*succeeded, "sanity"); 1613 return result; 1614 } 1615 1616 // Then, try a Full GC that will collect all soft references. 1617 gc_succeeded = do_collection(false, /* explicit_gc */ 1618 true, /* clear_all_soft_refs */ 1619 word_size); 1620 if (!gc_succeeded) { 1621 *succeeded = false; 1622 return NULL; 1623 } 1624 1625 // Retry the allocation once more 1626 result = attempt_allocation_at_safepoint(word_size, 1627 context, 1628 true /* expect_null_mutator_alloc_region */); 1629 if (result != NULL) { 1630 assert(*succeeded, "sanity"); 1631 return result; 1632 } 1633 1634 assert(!collector_policy()->should_clear_all_soft_refs(), 1635 "Flag should have been handled and cleared prior to this point"); 1636 1637 // What else? We might try synchronous finalization later. If the total 1638 // space available is large enough for the allocation, then a more 1639 // complete compaction phase than we've tried so far might be 1640 // appropriate. 1641 assert(*succeeded, "sanity"); 1642 return NULL; 1643 } 1644 1645 // Attempting to expand the heap sufficiently 1646 // to support an allocation of the given "word_size". If 1647 // successful, perform the allocation and return the address of the 1648 // allocated block, or else "NULL". 1649 1650 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) { 1651 assert_at_safepoint(true /* should_be_vm_thread */); 1652 1653 verify_region_sets_optional(); 1654 1655 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes); 1656 ergo_verbose1(ErgoHeapSizing, 1657 "attempt heap expansion", 1658 ergo_format_reason("allocation request failed") 1659 ergo_format_byte("allocation request"), 1660 word_size * HeapWordSize); 1661 if (expand(expand_bytes)) { 1662 _hrm.verify_optional(); 1663 verify_region_sets_optional(); 1664 return attempt_allocation_at_safepoint(word_size, 1665 context, 1666 false /* expect_null_mutator_alloc_region */); 1667 } 1668 return NULL; 1669 } 1670 1671 bool G1CollectedHeap::expand(size_t expand_bytes) { 1672 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); 1673 aligned_expand_bytes = align_size_up(aligned_expand_bytes, 1674 HeapRegion::GrainBytes); 1675 ergo_verbose2(ErgoHeapSizing, 1676 "expand the heap", 1677 ergo_format_byte("requested expansion amount") 1678 ergo_format_byte("attempted expansion amount"), 1679 expand_bytes, aligned_expand_bytes); 1680 1681 if (is_maximal_no_gc()) { 1682 ergo_verbose0(ErgoHeapSizing, 1683 "did not expand the heap", 1684 ergo_format_reason("heap already fully expanded")); 1685 return false; 1686 } 1687 1688 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes); 1689 assert(regions_to_expand > 0, "Must expand by at least one region"); 1690 1691 uint expanded_by = _hrm.expand_by(regions_to_expand); 1692 1693 if (expanded_by > 0) { 1694 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes; 1695 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition"); 1696 g1_policy()->record_new_heap_size(num_regions()); 1697 } else { 1698 ergo_verbose0(ErgoHeapSizing, 1699 "did not expand the heap", 1700 ergo_format_reason("heap expansion operation failed")); 1701 // The expansion of the virtual storage space was unsuccessful. 1702 // Let's see if it was because we ran out of swap. 1703 if (G1ExitOnExpansionFailure && 1704 _hrm.available() >= regions_to_expand) { 1705 // We had head room... 1706 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion"); 1707 } 1708 } 1709 return regions_to_expand > 0; 1710 } 1711 1712 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) { 1713 size_t aligned_shrink_bytes = 1714 ReservedSpace::page_align_size_down(shrink_bytes); 1715 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes, 1716 HeapRegion::GrainBytes); 1717 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes); 1718 1719 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove); 1720 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes; 1721 1722 ergo_verbose3(ErgoHeapSizing, 1723 "shrink the heap", 1724 ergo_format_byte("requested shrinking amount") 1725 ergo_format_byte("aligned shrinking amount") 1726 ergo_format_byte("attempted shrinking amount"), 1727 shrink_bytes, aligned_shrink_bytes, shrunk_bytes); 1728 if (num_regions_removed > 0) { 1729 g1_policy()->record_new_heap_size(num_regions()); 1730 } else { 1731 ergo_verbose0(ErgoHeapSizing, 1732 "did not shrink the heap", 1733 ergo_format_reason("heap shrinking operation failed")); 1734 } 1735 } 1736 1737 void G1CollectedHeap::shrink(size_t shrink_bytes) { 1738 verify_region_sets_optional(); 1739 1740 // We should only reach here at the end of a Full GC which means we 1741 // should not not be holding to any GC alloc regions. The method 1742 // below will make sure of that and do any remaining clean up. 1743 _allocator->abandon_gc_alloc_regions(); 1744 1745 // Instead of tearing down / rebuilding the free lists here, we 1746 // could instead use the remove_all_pending() method on free_list to 1747 // remove only the ones that we need to remove. 1748 tear_down_region_sets(true /* free_list_only */); 1749 shrink_helper(shrink_bytes); 1750 rebuild_region_sets(true /* free_list_only */); 1751 1752 _hrm.verify_optional(); 1753 verify_region_sets_optional(); 1754 } 1755 1756 // Public methods. 1757 1758 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away 1759 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list 1760 #endif // _MSC_VER 1761 1762 1763 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) : 1764 SharedHeap(policy_), 1765 _g1_policy(policy_), 1766 _dirty_card_queue_set(false), 1767 _into_cset_dirty_card_queue_set(false), 1768 _is_alive_closure_cm(this), 1769 _is_alive_closure_stw(this), 1770 _ref_processor_cm(NULL), 1771 _ref_processor_stw(NULL), 1772 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)), 1773 _bot_shared(NULL), 1774 _evac_failure_scan_stack(NULL), 1775 _mark_in_progress(false), 1776 _cg1r(NULL), 1777 _g1mm(NULL), 1778 _refine_cte_cl(NULL), 1779 _full_collection(false), 1780 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()), 1781 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()), 1782 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()), 1783 _humongous_is_live(), 1784 _has_humongous_reclaim_candidates(false), 1785 _free_regions_coming(false), 1786 _young_list(new YoungList(this)), 1787 _gc_time_stamp(0), 1788 _survivor_plab_stats(YoungPLABSize, PLABWeight), 1789 _old_plab_stats(OldPLABSize, PLABWeight), 1790 _expand_heap_after_alloc_failure(true), 1791 _surviving_young_words(NULL), 1792 _old_marking_cycles_started(0), 1793 _old_marking_cycles_completed(0), 1794 _concurrent_cycle_started(false), 1795 _heap_summary_sent(false), 1796 _in_cset_fast_test(), 1797 _dirty_cards_region_list(NULL), 1798 _worker_cset_start_region(NULL), 1799 _worker_cset_start_region_time_stamp(NULL), 1800 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()), 1801 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()), 1802 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()), 1803 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) { 1804 1805 _g1h = this; 1806 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) { 1807 vm_exit_during_initialization("Failed necessary allocation."); 1808 } 1809 1810 _allocator = G1Allocator::create_allocator(_g1h); 1811 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2; 1812 1813 int n_queues = MAX2((int)ParallelGCThreads, 1); 1814 _task_queues = new RefToScanQueueSet(n_queues); 1815 1816 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets(); 1817 assert(n_rem_sets > 0, "Invariant."); 1818 1819 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC); 1820 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(unsigned int, n_queues, mtGC); 1821 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC); 1822 1823 for (int i = 0; i < n_queues; i++) { 1824 RefToScanQueue* q = new RefToScanQueue(); 1825 q->initialize(); 1826 _task_queues->register_queue(i, q); 1827 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo(); 1828 } 1829 clear_cset_start_regions(); 1830 1831 // Initialize the G1EvacuationFailureALot counters and flags. 1832 NOT_PRODUCT(reset_evacuation_should_fail();) 1833 1834 guarantee(_task_queues != NULL, "task_queues allocation failure."); 1835 } 1836 1837 jint G1CollectedHeap::initialize() { 1838 CollectedHeap::pre_initialize(); 1839 os::enable_vtime(); 1840 1841 G1Log::init(); 1842 1843 // Necessary to satisfy locking discipline assertions. 1844 1845 MutexLocker x(Heap_lock); 1846 1847 // We have to initialize the printer before committing the heap, as 1848 // it will be used then. 1849 _hr_printer.set_active(G1PrintHeapRegions); 1850 1851 // While there are no constraints in the GC code that HeapWordSize 1852 // be any particular value, there are multiple other areas in the 1853 // system which believe this to be true (e.g. oop->object_size in some 1854 // cases incorrectly returns the size in wordSize units rather than 1855 // HeapWordSize). 1856 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 1857 1858 size_t init_byte_size = collector_policy()->initial_heap_byte_size(); 1859 size_t max_byte_size = collector_policy()->max_heap_byte_size(); 1860 size_t heap_alignment = collector_policy()->heap_alignment(); 1861 1862 // Ensure that the sizes are properly aligned. 1863 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1864 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1865 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap"); 1866 1867 _refine_cte_cl = new RefineCardTableEntryClosure(); 1868 1869 _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl); 1870 1871 // Reserve the maximum. 1872 1873 // When compressed oops are enabled, the preferred heap base 1874 // is calculated by subtracting the requested size from the 1875 // 32Gb boundary and using the result as the base address for 1876 // heap reservation. If the requested size is not aligned to 1877 // HeapRegion::GrainBytes (i.e. the alignment that is passed 1878 // into the ReservedHeapSpace constructor) then the actual 1879 // base of the reserved heap may end up differing from the 1880 // address that was requested (i.e. the preferred heap base). 1881 // If this happens then we could end up using a non-optimal 1882 // compressed oops mode. 1883 1884 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size, 1885 heap_alignment); 1886 1887 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size())); 1888 1889 // Create the barrier set for the entire reserved region. 1890 G1SATBCardTableLoggingModRefBS* bs 1891 = new G1SATBCardTableLoggingModRefBS(reserved_region()); 1892 bs->initialize(); 1893 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity"); 1894 set_barrier_set(bs); 1895 1896 // Also create a G1 rem set. 1897 _g1_rem_set = new G1RemSet(this, g1_barrier_set()); 1898 1899 // Carve out the G1 part of the heap. 1900 1901 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size); 1902 G1RegionToSpaceMapper* heap_storage = 1903 G1RegionToSpaceMapper::create_mapper(g1_rs, 1904 UseLargePages ? os::large_page_size() : os::vm_page_size(), 1905 HeapRegion::GrainBytes, 1906 1, 1907 mtJavaHeap); 1908 heap_storage->set_mapping_changed_listener(&_listener); 1909 1910 // Reserve space for the block offset table. We do not support automatic uncommit 1911 // for the card table at this time. BOT only. 1912 ReservedSpace bot_rs(G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize)); 1913 G1RegionToSpaceMapper* bot_storage = 1914 G1RegionToSpaceMapper::create_mapper(bot_rs, 1915 os::vm_page_size(), 1916 HeapRegion::GrainBytes, 1917 G1BlockOffsetSharedArray::N_bytes, 1918 mtGC); 1919 1920 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize)); 1921 G1RegionToSpaceMapper* cardtable_storage = 1922 G1RegionToSpaceMapper::create_mapper(cardtable_rs, 1923 os::vm_page_size(), 1924 HeapRegion::GrainBytes, 1925 G1BlockOffsetSharedArray::N_bytes, 1926 mtGC); 1927 1928 // Reserve space for the card counts table. 1929 ReservedSpace card_counts_rs(G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize)); 1930 G1RegionToSpaceMapper* card_counts_storage = 1931 G1RegionToSpaceMapper::create_mapper(card_counts_rs, 1932 os::vm_page_size(), 1933 HeapRegion::GrainBytes, 1934 G1BlockOffsetSharedArray::N_bytes, 1935 mtGC); 1936 1937 // Reserve space for prev and next bitmap. 1938 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size()); 1939 1940 ReservedSpace prev_bitmap_rs(ReservedSpace::allocation_align_size_up(bitmap_size)); 1941 G1RegionToSpaceMapper* prev_bitmap_storage = 1942 G1RegionToSpaceMapper::create_mapper(prev_bitmap_rs, 1943 os::vm_page_size(), 1944 HeapRegion::GrainBytes, 1945 CMBitMap::mark_distance(), 1946 mtGC); 1947 1948 ReservedSpace next_bitmap_rs(ReservedSpace::allocation_align_size_up(bitmap_size)); 1949 G1RegionToSpaceMapper* next_bitmap_storage = 1950 G1RegionToSpaceMapper::create_mapper(next_bitmap_rs, 1951 os::vm_page_size(), 1952 HeapRegion::GrainBytes, 1953 CMBitMap::mark_distance(), 1954 mtGC); 1955 1956 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage); 1957 g1_barrier_set()->initialize(cardtable_storage); 1958 // Do later initialization work for concurrent refinement. 1959 _cg1r->init(card_counts_storage); 1960 1961 // 6843694 - ensure that the maximum region index can fit 1962 // in the remembered set structures. 1963 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; 1964 guarantee((max_regions() - 1) <= max_region_idx, "too many regions"); 1965 1966 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; 1967 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); 1968 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region, 1969 "too many cards per region"); 1970 1971 FreeRegionList::set_unrealistically_long_length(max_regions() + 1); 1972 1973 _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage); 1974 1975 _g1h = this; 1976 1977 _in_cset_fast_test.initialize(_hrm.reserved().start(), _hrm.reserved().end(), HeapRegion::GrainBytes); 1978 _humongous_is_live.initialize(_hrm.reserved().start(), _hrm.reserved().end(), HeapRegion::GrainBytes); 1979 1980 // Create the ConcurrentMark data structure and thread. 1981 // (Must do this late, so that "max_regions" is defined.) 1982 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage); 1983 if (_cm == NULL || !_cm->completed_initialization()) { 1984 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark"); 1985 return JNI_ENOMEM; 1986 } 1987 _cmThread = _cm->cmThread(); 1988 1989 // Initialize the from_card cache structure of HeapRegionRemSet. 1990 HeapRegionRemSet::init_heap(max_regions()); 1991 1992 // Now expand into the initial heap size. 1993 if (!expand(init_byte_size)) { 1994 vm_shutdown_during_initialization("Failed to allocate initial heap."); 1995 return JNI_ENOMEM; 1996 } 1997 1998 // Perform any initialization actions delegated to the policy. 1999 g1_policy()->init(); 2000 2001 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon, 2002 SATB_Q_FL_lock, 2003 G1SATBProcessCompletedThreshold, 2004 Shared_SATB_Q_lock); 2005 2006 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl, 2007 DirtyCardQ_CBL_mon, 2008 DirtyCardQ_FL_lock, 2009 concurrent_g1_refine()->yellow_zone(), 2010 concurrent_g1_refine()->red_zone(), 2011 Shared_DirtyCardQ_lock); 2012 2013 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code 2014 DirtyCardQ_CBL_mon, 2015 DirtyCardQ_FL_lock, 2016 -1, // never trigger processing 2017 -1, // no limit on length 2018 Shared_DirtyCardQ_lock, 2019 &JavaThread::dirty_card_queue_set()); 2020 2021 // Initialize the card queue set used to hold cards containing 2022 // references into the collection set. 2023 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code 2024 DirtyCardQ_CBL_mon, 2025 DirtyCardQ_FL_lock, 2026 -1, // never trigger processing 2027 -1, // no limit on length 2028 Shared_DirtyCardQ_lock, 2029 &JavaThread::dirty_card_queue_set()); 2030 2031 // In case we're keeping closure specialization stats, initialize those 2032 // counts and that mechanism. 2033 SpecializationStats::clear(); 2034 2035 // Here we allocate the dummy HeapRegion that is required by the 2036 // G1AllocRegion class. 2037 HeapRegion* dummy_region = _hrm.get_dummy_region(); 2038 2039 // We'll re-use the same region whether the alloc region will 2040 // require BOT updates or not and, if it doesn't, then a non-young 2041 // region will complain that it cannot support allocations without 2042 // BOT updates. So we'll tag the dummy region as eden to avoid that. 2043 dummy_region->set_eden(); 2044 // Make sure it's full. 2045 dummy_region->set_top(dummy_region->end()); 2046 G1AllocRegion::setup(this, dummy_region); 2047 2048 _allocator->init_mutator_alloc_region(); 2049 2050 // Do create of the monitoring and management support so that 2051 // values in the heap have been properly initialized. 2052 _g1mm = new G1MonitoringSupport(this); 2053 2054 G1StringDedup::initialize(); 2055 2056 return JNI_OK; 2057 } 2058 2059 void G1CollectedHeap::stop() { 2060 // Stop all concurrent threads. We do this to make sure these threads 2061 // do not continue to execute and access resources (e.g. gclog_or_tty) 2062 // that are destroyed during shutdown. 2063 _cg1r->stop(); 2064 _cmThread->stop(); 2065 if (G1StringDedup::is_enabled()) { 2066 G1StringDedup::stop(); 2067 } 2068 } 2069 2070 void G1CollectedHeap::clear_humongous_is_live_table() { 2071 guarantee(G1EagerReclaimHumongousObjects, "Should only be called if true"); 2072 _humongous_is_live.clear(); 2073 } 2074 2075 size_t G1CollectedHeap::conservative_max_heap_alignment() { 2076 return HeapRegion::max_region_size(); 2077 } 2078 2079 void G1CollectedHeap::ref_processing_init() { 2080 // Reference processing in G1 currently works as follows: 2081 // 2082 // * There are two reference processor instances. One is 2083 // used to record and process discovered references 2084 // during concurrent marking; the other is used to 2085 // record and process references during STW pauses 2086 // (both full and incremental). 2087 // * Both ref processors need to 'span' the entire heap as 2088 // the regions in the collection set may be dotted around. 2089 // 2090 // * For the concurrent marking ref processor: 2091 // * Reference discovery is enabled at initial marking. 2092 // * Reference discovery is disabled and the discovered 2093 // references processed etc during remarking. 2094 // * Reference discovery is MT (see below). 2095 // * Reference discovery requires a barrier (see below). 2096 // * Reference processing may or may not be MT 2097 // (depending on the value of ParallelRefProcEnabled 2098 // and ParallelGCThreads). 2099 // * A full GC disables reference discovery by the CM 2100 // ref processor and abandons any entries on it's 2101 // discovered lists. 2102 // 2103 // * For the STW processor: 2104 // * Non MT discovery is enabled at the start of a full GC. 2105 // * Processing and enqueueing during a full GC is non-MT. 2106 // * During a full GC, references are processed after marking. 2107 // 2108 // * Discovery (may or may not be MT) is enabled at the start 2109 // of an incremental evacuation pause. 2110 // * References are processed near the end of a STW evacuation pause. 2111 // * For both types of GC: 2112 // * Discovery is atomic - i.e. not concurrent. 2113 // * Reference discovery will not need a barrier. 2114 2115 SharedHeap::ref_processing_init(); 2116 MemRegion mr = reserved_region(); 2117 2118 // Concurrent Mark ref processor 2119 _ref_processor_cm = 2120 new ReferenceProcessor(mr, // span 2121 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2122 // mt processing 2123 (int) ParallelGCThreads, 2124 // degree of mt processing 2125 (ParallelGCThreads > 1) || (ConcGCThreads > 1), 2126 // mt discovery 2127 (int) MAX2(ParallelGCThreads, ConcGCThreads), 2128 // degree of mt discovery 2129 false, 2130 // Reference discovery is not atomic 2131 &_is_alive_closure_cm); 2132 // is alive closure 2133 // (for efficiency/performance) 2134 2135 // STW ref processor 2136 _ref_processor_stw = 2137 new ReferenceProcessor(mr, // span 2138 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2139 // mt processing 2140 MAX2((int)ParallelGCThreads, 1), 2141 // degree of mt processing 2142 (ParallelGCThreads > 1), 2143 // mt discovery 2144 MAX2((int)ParallelGCThreads, 1), 2145 // degree of mt discovery 2146 true, 2147 // Reference discovery is atomic 2148 &_is_alive_closure_stw); 2149 // is alive closure 2150 // (for efficiency/performance) 2151 } 2152 2153 size_t G1CollectedHeap::capacity() const { 2154 return _hrm.length() * HeapRegion::GrainBytes; 2155 } 2156 2157 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) { 2158 assert(!hr->is_continues_humongous(), "pre-condition"); 2159 hr->reset_gc_time_stamp(); 2160 if (hr->is_starts_humongous()) { 2161 uint first_index = hr->hrm_index() + 1; 2162 uint last_index = hr->last_hc_index(); 2163 for (uint i = first_index; i < last_index; i += 1) { 2164 HeapRegion* chr = region_at(i); 2165 assert(chr->is_continues_humongous(), "sanity"); 2166 chr->reset_gc_time_stamp(); 2167 } 2168 } 2169 } 2170 2171 #ifndef PRODUCT 2172 class CheckGCTimeStampsHRClosure : public HeapRegionClosure { 2173 private: 2174 unsigned _gc_time_stamp; 2175 bool _failures; 2176 2177 public: 2178 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) : 2179 _gc_time_stamp(gc_time_stamp), _failures(false) { } 2180 2181 virtual bool doHeapRegion(HeapRegion* hr) { 2182 unsigned region_gc_time_stamp = hr->get_gc_time_stamp(); 2183 if (_gc_time_stamp != region_gc_time_stamp) { 2184 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, " 2185 "expected %d", HR_FORMAT_PARAMS(hr), 2186 region_gc_time_stamp, _gc_time_stamp); 2187 _failures = true; 2188 } 2189 return false; 2190 } 2191 2192 bool failures() { return _failures; } 2193 }; 2194 2195 void G1CollectedHeap::check_gc_time_stamps() { 2196 CheckGCTimeStampsHRClosure cl(_gc_time_stamp); 2197 heap_region_iterate(&cl); 2198 guarantee(!cl.failures(), "all GC time stamps should have been reset"); 2199 } 2200 #endif // PRODUCT 2201 2202 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, 2203 DirtyCardQueue* into_cset_dcq, 2204 bool concurrent, 2205 uint worker_i) { 2206 // Clean cards in the hot card cache 2207 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 2208 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq); 2209 2210 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 2211 int n_completed_buffers = 0; 2212 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) { 2213 n_completed_buffers++; 2214 } 2215 g1_policy()->phase_times()->record_update_rs_processed_buffers(worker_i, n_completed_buffers); 2216 dcqs.clear_n_completed_buffers(); 2217 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!"); 2218 } 2219 2220 2221 // Computes the sum of the storage used by the various regions. 2222 size_t G1CollectedHeap::used() const { 2223 return _allocator->used(); 2224 } 2225 2226 size_t G1CollectedHeap::used_unlocked() const { 2227 return _allocator->used_unlocked(); 2228 } 2229 2230 class SumUsedClosure: public HeapRegionClosure { 2231 size_t _used; 2232 public: 2233 SumUsedClosure() : _used(0) {} 2234 bool doHeapRegion(HeapRegion* r) { 2235 if (!r->is_continues_humongous()) { 2236 _used += r->used(); 2237 } 2238 return false; 2239 } 2240 size_t result() { return _used; } 2241 }; 2242 2243 size_t G1CollectedHeap::recalculate_used() const { 2244 double recalculate_used_start = os::elapsedTime(); 2245 2246 SumUsedClosure blk; 2247 heap_region_iterate(&blk); 2248 2249 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0); 2250 return blk.result(); 2251 } 2252 2253 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 2254 switch (cause) { 2255 case GCCause::_gc_locker: return GCLockerInvokesConcurrent; 2256 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent; 2257 case GCCause::_g1_humongous_allocation: return true; 2258 case GCCause::_update_allocation_context_stats_inc: return true; 2259 case GCCause::_wb_conc_mark: return true; 2260 default: return false; 2261 } 2262 } 2263 2264 #ifndef PRODUCT 2265 void G1CollectedHeap::allocate_dummy_regions() { 2266 // Let's fill up most of the region 2267 size_t word_size = HeapRegion::GrainWords - 1024; 2268 // And as a result the region we'll allocate will be humongous. 2269 guarantee(is_humongous(word_size), "sanity"); 2270 2271 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) { 2272 // Let's use the existing mechanism for the allocation 2273 HeapWord* dummy_obj = humongous_obj_allocate(word_size, 2274 AllocationContext::system()); 2275 if (dummy_obj != NULL) { 2276 MemRegion mr(dummy_obj, word_size); 2277 CollectedHeap::fill_with_object(mr); 2278 } else { 2279 // If we can't allocate once, we probably cannot allocate 2280 // again. Let's get out of the loop. 2281 break; 2282 } 2283 } 2284 } 2285 #endif // !PRODUCT 2286 2287 void G1CollectedHeap::increment_old_marking_cycles_started() { 2288 assert(_old_marking_cycles_started == _old_marking_cycles_completed || 2289 _old_marking_cycles_started == _old_marking_cycles_completed + 1, 2290 err_msg("Wrong marking cycle count (started: %d, completed: %d)", 2291 _old_marking_cycles_started, _old_marking_cycles_completed)); 2292 2293 _old_marking_cycles_started++; 2294 } 2295 2296 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) { 2297 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 2298 2299 // We assume that if concurrent == true, then the caller is a 2300 // concurrent thread that was joined the Suspendible Thread 2301 // Set. If there's ever a cheap way to check this, we should add an 2302 // assert here. 2303 2304 // Given that this method is called at the end of a Full GC or of a 2305 // concurrent cycle, and those can be nested (i.e., a Full GC can 2306 // interrupt a concurrent cycle), the number of full collections 2307 // completed should be either one (in the case where there was no 2308 // nesting) or two (when a Full GC interrupted a concurrent cycle) 2309 // behind the number of full collections started. 2310 2311 // This is the case for the inner caller, i.e. a Full GC. 2312 assert(concurrent || 2313 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || 2314 (_old_marking_cycles_started == _old_marking_cycles_completed + 2), 2315 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u " 2316 "is inconsistent with _old_marking_cycles_completed = %u", 2317 _old_marking_cycles_started, _old_marking_cycles_completed)); 2318 2319 // This is the case for the outer caller, i.e. the concurrent cycle. 2320 assert(!concurrent || 2321 (_old_marking_cycles_started == _old_marking_cycles_completed + 1), 2322 err_msg("for outer caller (concurrent cycle): " 2323 "_old_marking_cycles_started = %u " 2324 "is inconsistent with _old_marking_cycles_completed = %u", 2325 _old_marking_cycles_started, _old_marking_cycles_completed)); 2326 2327 _old_marking_cycles_completed += 1; 2328 2329 // We need to clear the "in_progress" flag in the CM thread before 2330 // we wake up any waiters (especially when ExplicitInvokesConcurrent 2331 // is set) so that if a waiter requests another System.gc() it doesn't 2332 // incorrectly see that a marking cycle is still in progress. 2333 if (concurrent) { 2334 _cmThread->clear_in_progress(); 2335 } 2336 2337 // This notify_all() will ensure that a thread that called 2338 // System.gc() with (with ExplicitGCInvokesConcurrent set or not) 2339 // and it's waiting for a full GC to finish will be woken up. It is 2340 // waiting in VM_G1IncCollectionPause::doit_epilogue(). 2341 FullGCCount_lock->notify_all(); 2342 } 2343 2344 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) { 2345 _concurrent_cycle_started = true; 2346 _gc_timer_cm->register_gc_start(start_time); 2347 2348 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start()); 2349 trace_heap_before_gc(_gc_tracer_cm); 2350 } 2351 2352 void G1CollectedHeap::register_concurrent_cycle_end() { 2353 if (_concurrent_cycle_started) { 2354 if (_cm->has_aborted()) { 2355 _gc_tracer_cm->report_concurrent_mode_failure(); 2356 } 2357 2358 _gc_timer_cm->register_gc_end(); 2359 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions()); 2360 2361 // Clear state variables to prepare for the next concurrent cycle. 2362 _concurrent_cycle_started = false; 2363 _heap_summary_sent = false; 2364 } 2365 } 2366 2367 void G1CollectedHeap::trace_heap_after_concurrent_cycle() { 2368 if (_concurrent_cycle_started) { 2369 // This function can be called when: 2370 // the cleanup pause is run 2371 // the concurrent cycle is aborted before the cleanup pause. 2372 // the concurrent cycle is aborted after the cleanup pause, 2373 // but before the concurrent cycle end has been registered. 2374 // Make sure that we only send the heap information once. 2375 if (!_heap_summary_sent) { 2376 trace_heap_after_gc(_gc_tracer_cm); 2377 _heap_summary_sent = true; 2378 } 2379 } 2380 } 2381 2382 G1YCType G1CollectedHeap::yc_type() { 2383 bool is_young = g1_policy()->gcs_are_young(); 2384 bool is_initial_mark = g1_policy()->during_initial_mark_pause(); 2385 bool is_during_mark = mark_in_progress(); 2386 2387 if (is_initial_mark) { 2388 return InitialMark; 2389 } else if (is_during_mark) { 2390 return DuringMark; 2391 } else if (is_young) { 2392 return Normal; 2393 } else { 2394 return Mixed; 2395 } 2396 } 2397 2398 void G1CollectedHeap::collect(GCCause::Cause cause) { 2399 assert_heap_not_locked(); 2400 2401 unsigned int gc_count_before; 2402 unsigned int old_marking_count_before; 2403 unsigned int full_gc_count_before; 2404 bool retry_gc; 2405 2406 do { 2407 retry_gc = false; 2408 2409 { 2410 MutexLocker ml(Heap_lock); 2411 2412 // Read the GC count while holding the Heap_lock 2413 gc_count_before = total_collections(); 2414 full_gc_count_before = total_full_collections(); 2415 old_marking_count_before = _old_marking_cycles_started; 2416 } 2417 2418 if (should_do_concurrent_full_gc(cause)) { 2419 // Schedule an initial-mark evacuation pause that will start a 2420 // concurrent cycle. We're setting word_size to 0 which means that 2421 // we are not requesting a post-GC allocation. 2422 VM_G1IncCollectionPause op(gc_count_before, 2423 0, /* word_size */ 2424 true, /* should_initiate_conc_mark */ 2425 g1_policy()->max_pause_time_ms(), 2426 cause); 2427 op.set_allocation_context(AllocationContext::current()); 2428 2429 VMThread::execute(&op); 2430 if (!op.pause_succeeded()) { 2431 if (old_marking_count_before == _old_marking_cycles_started) { 2432 retry_gc = op.should_retry_gc(); 2433 } else { 2434 // A Full GC happened while we were trying to schedule the 2435 // initial-mark GC. No point in starting a new cycle given 2436 // that the whole heap was collected anyway. 2437 } 2438 2439 if (retry_gc) { 2440 if (GC_locker::is_active_and_needs_gc()) { 2441 GC_locker::stall_until_clear(); 2442 } 2443 } 2444 } 2445 } else { 2446 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc 2447 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { 2448 2449 // Schedule a standard evacuation pause. We're setting word_size 2450 // to 0 which means that we are not requesting a post-GC allocation. 2451 VM_G1IncCollectionPause op(gc_count_before, 2452 0, /* word_size */ 2453 false, /* should_initiate_conc_mark */ 2454 g1_policy()->max_pause_time_ms(), 2455 cause); 2456 VMThread::execute(&op); 2457 } else { 2458 // Schedule a Full GC. 2459 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause); 2460 VMThread::execute(&op); 2461 } 2462 } 2463 } while (retry_gc); 2464 } 2465 2466 bool G1CollectedHeap::is_in(const void* p) const { 2467 if (_hrm.reserved().contains(p)) { 2468 // Given that we know that p is in the reserved space, 2469 // heap_region_containing_raw() should successfully 2470 // return the containing region. 2471 HeapRegion* hr = heap_region_containing_raw(p); 2472 return hr->is_in(p); 2473 } else { 2474 return false; 2475 } 2476 } 2477 2478 #ifdef ASSERT 2479 bool G1CollectedHeap::is_in_exact(const void* p) const { 2480 bool contains = reserved_region().contains(p); 2481 bool available = _hrm.is_available(addr_to_region((HeapWord*)p)); 2482 if (contains && available) { 2483 return true; 2484 } else { 2485 return false; 2486 } 2487 } 2488 #endif 2489 2490 // Iteration functions. 2491 2492 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion. 2493 2494 class IterateOopClosureRegionClosure: public HeapRegionClosure { 2495 ExtendedOopClosure* _cl; 2496 public: 2497 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {} 2498 bool doHeapRegion(HeapRegion* r) { 2499 if (!r->is_continues_humongous()) { 2500 r->oop_iterate(_cl); 2501 } 2502 return false; 2503 } 2504 }; 2505 2506 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) { 2507 IterateOopClosureRegionClosure blk(cl); 2508 heap_region_iterate(&blk); 2509 } 2510 2511 // Iterates an ObjectClosure over all objects within a HeapRegion. 2512 2513 class IterateObjectClosureRegionClosure: public HeapRegionClosure { 2514 ObjectClosure* _cl; 2515 public: 2516 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} 2517 bool doHeapRegion(HeapRegion* r) { 2518 if (!r->is_continues_humongous()) { 2519 r->object_iterate(_cl); 2520 } 2521 return false; 2522 } 2523 }; 2524 2525 void G1CollectedHeap::object_iterate(ObjectClosure* cl) { 2526 IterateObjectClosureRegionClosure blk(cl); 2527 heap_region_iterate(&blk); 2528 } 2529 2530 // Calls a SpaceClosure on a HeapRegion. 2531 2532 class SpaceClosureRegionClosure: public HeapRegionClosure { 2533 SpaceClosure* _cl; 2534 public: 2535 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {} 2536 bool doHeapRegion(HeapRegion* r) { 2537 _cl->do_space(r); 2538 return false; 2539 } 2540 }; 2541 2542 void G1CollectedHeap::space_iterate(SpaceClosure* cl) { 2543 SpaceClosureRegionClosure blk(cl); 2544 heap_region_iterate(&blk); 2545 } 2546 2547 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { 2548 _hrm.iterate(cl); 2549 } 2550 2551 void 2552 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl, 2553 uint worker_id, 2554 HeapRegionClaimer *hrclaimer, 2555 bool concurrent) const { 2556 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent); 2557 } 2558 2559 // Clear the cached CSet starting regions and (more importantly) 2560 // the time stamps. Called when we reset the GC time stamp. 2561 void G1CollectedHeap::clear_cset_start_regions() { 2562 assert(_worker_cset_start_region != NULL, "sanity"); 2563 assert(_worker_cset_start_region_time_stamp != NULL, "sanity"); 2564 2565 int n_queues = MAX2((int)ParallelGCThreads, 1); 2566 for (int i = 0; i < n_queues; i++) { 2567 _worker_cset_start_region[i] = NULL; 2568 _worker_cset_start_region_time_stamp[i] = 0; 2569 } 2570 } 2571 2572 // Given the id of a worker, obtain or calculate a suitable 2573 // starting region for iterating over the current collection set. 2574 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) { 2575 assert(get_gc_time_stamp() > 0, "should have been updated by now"); 2576 2577 HeapRegion* result = NULL; 2578 unsigned gc_time_stamp = get_gc_time_stamp(); 2579 2580 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) { 2581 // Cached starting region for current worker was set 2582 // during the current pause - so it's valid. 2583 // Note: the cached starting heap region may be NULL 2584 // (when the collection set is empty). 2585 result = _worker_cset_start_region[worker_i]; 2586 assert(result == NULL || result->in_collection_set(), "sanity"); 2587 return result; 2588 } 2589 2590 // The cached entry was not valid so let's calculate 2591 // a suitable starting heap region for this worker. 2592 2593 // We want the parallel threads to start their collection 2594 // set iteration at different collection set regions to 2595 // avoid contention. 2596 // If we have: 2597 // n collection set regions 2598 // p threads 2599 // Then thread t will start at region floor ((t * n) / p) 2600 2601 result = g1_policy()->collection_set(); 2602 uint cs_size = g1_policy()->cset_region_length(); 2603 uint active_workers = workers()->active_workers(); 2604 assert(UseDynamicNumberOfGCThreads || 2605 active_workers == workers()->total_workers(), 2606 "Unless dynamic should use total workers"); 2607 2608 uint end_ind = (cs_size * worker_i) / active_workers; 2609 uint start_ind = 0; 2610 2611 if (worker_i > 0 && 2612 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) { 2613 // Previous workers starting region is valid 2614 // so let's iterate from there 2615 start_ind = (cs_size * (worker_i - 1)) / active_workers; 2616 result = _worker_cset_start_region[worker_i - 1]; 2617 } 2618 2619 for (uint i = start_ind; i < end_ind; i++) { 2620 result = result->next_in_collection_set(); 2621 } 2622 2623 // Note: the calculated starting heap region may be NULL 2624 // (when the collection set is empty). 2625 assert(result == NULL || result->in_collection_set(), "sanity"); 2626 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp, 2627 "should be updated only once per pause"); 2628 _worker_cset_start_region[worker_i] = result; 2629 OrderAccess::storestore(); 2630 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp; 2631 return result; 2632 } 2633 2634 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) { 2635 HeapRegion* r = g1_policy()->collection_set(); 2636 while (r != NULL) { 2637 HeapRegion* next = r->next_in_collection_set(); 2638 if (cl->doHeapRegion(r)) { 2639 cl->incomplete(); 2640 return; 2641 } 2642 r = next; 2643 } 2644 } 2645 2646 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r, 2647 HeapRegionClosure *cl) { 2648 if (r == NULL) { 2649 // The CSet is empty so there's nothing to do. 2650 return; 2651 } 2652 2653 assert(r->in_collection_set(), 2654 "Start region must be a member of the collection set."); 2655 HeapRegion* cur = r; 2656 while (cur != NULL) { 2657 HeapRegion* next = cur->next_in_collection_set(); 2658 if (cl->doHeapRegion(cur) && false) { 2659 cl->incomplete(); 2660 return; 2661 } 2662 cur = next; 2663 } 2664 cur = g1_policy()->collection_set(); 2665 while (cur != r) { 2666 HeapRegion* next = cur->next_in_collection_set(); 2667 if (cl->doHeapRegion(cur) && false) { 2668 cl->incomplete(); 2669 return; 2670 } 2671 cur = next; 2672 } 2673 } 2674 2675 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const { 2676 HeapRegion* result = _hrm.next_region_in_heap(from); 2677 while (result != NULL && result->is_humongous()) { 2678 result = _hrm.next_region_in_heap(result); 2679 } 2680 return result; 2681 } 2682 2683 Space* G1CollectedHeap::space_containing(const void* addr) const { 2684 return heap_region_containing(addr); 2685 } 2686 2687 HeapWord* G1CollectedHeap::block_start(const void* addr) const { 2688 Space* sp = space_containing(addr); 2689 return sp->block_start(addr); 2690 } 2691 2692 size_t G1CollectedHeap::block_size(const HeapWord* addr) const { 2693 Space* sp = space_containing(addr); 2694 return sp->block_size(addr); 2695 } 2696 2697 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { 2698 Space* sp = space_containing(addr); 2699 return sp->block_is_obj(addr); 2700 } 2701 2702 bool G1CollectedHeap::supports_tlab_allocation() const { 2703 return true; 2704 } 2705 2706 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { 2707 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes; 2708 } 2709 2710 size_t G1CollectedHeap::tlab_used(Thread* ignored) const { 2711 return young_list()->eden_used_bytes(); 2712 } 2713 2714 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size 2715 // must be smaller than the humongous object limit. 2716 size_t G1CollectedHeap::max_tlab_size() const { 2717 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment); 2718 } 2719 2720 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { 2721 // Return the remaining space in the cur alloc region, but not less than 2722 // the min TLAB size. 2723 2724 // Also, this value can be at most the humongous object threshold, 2725 // since we can't allow tlabs to grow big enough to accommodate 2726 // humongous objects. 2727 2728 HeapRegion* hr = _allocator->mutator_alloc_region(AllocationContext::current())->get(); 2729 size_t max_tlab = max_tlab_size() * wordSize; 2730 if (hr == NULL) { 2731 return max_tlab; 2732 } else { 2733 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab); 2734 } 2735 } 2736 2737 size_t G1CollectedHeap::max_capacity() const { 2738 return _hrm.reserved().byte_size(); 2739 } 2740 2741 jlong G1CollectedHeap::millis_since_last_gc() { 2742 // assert(false, "NYI"); 2743 return 0; 2744 } 2745 2746 void G1CollectedHeap::prepare_for_verify() { 2747 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) { 2748 ensure_parsability(false); 2749 } 2750 g1_rem_set()->prepare_for_verify(); 2751 } 2752 2753 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr, 2754 VerifyOption vo) { 2755 switch (vo) { 2756 case VerifyOption_G1UsePrevMarking: 2757 return hr->obj_allocated_since_prev_marking(obj); 2758 case VerifyOption_G1UseNextMarking: 2759 return hr->obj_allocated_since_next_marking(obj); 2760 case VerifyOption_G1UseMarkWord: 2761 return false; 2762 default: 2763 ShouldNotReachHere(); 2764 } 2765 return false; // keep some compilers happy 2766 } 2767 2768 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) { 2769 switch (vo) { 2770 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start(); 2771 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start(); 2772 case VerifyOption_G1UseMarkWord: return NULL; 2773 default: ShouldNotReachHere(); 2774 } 2775 return NULL; // keep some compilers happy 2776 } 2777 2778 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) { 2779 switch (vo) { 2780 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj); 2781 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj); 2782 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked(); 2783 default: ShouldNotReachHere(); 2784 } 2785 return false; // keep some compilers happy 2786 } 2787 2788 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) { 2789 switch (vo) { 2790 case VerifyOption_G1UsePrevMarking: return "PTAMS"; 2791 case VerifyOption_G1UseNextMarking: return "NTAMS"; 2792 case VerifyOption_G1UseMarkWord: return "NONE"; 2793 default: ShouldNotReachHere(); 2794 } 2795 return NULL; // keep some compilers happy 2796 } 2797 2798 class VerifyRootsClosure: public OopClosure { 2799 private: 2800 G1CollectedHeap* _g1h; 2801 VerifyOption _vo; 2802 bool _failures; 2803 public: 2804 // _vo == UsePrevMarking -> use "prev" marking information, 2805 // _vo == UseNextMarking -> use "next" marking information, 2806 // _vo == UseMarkWord -> use mark word from object header. 2807 VerifyRootsClosure(VerifyOption vo) : 2808 _g1h(G1CollectedHeap::heap()), 2809 _vo(vo), 2810 _failures(false) { } 2811 2812 bool failures() { return _failures; } 2813 2814 template <class T> void do_oop_nv(T* p) { 2815 T heap_oop = oopDesc::load_heap_oop(p); 2816 if (!oopDesc::is_null(heap_oop)) { 2817 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 2818 if (_g1h->is_obj_dead_cond(obj, _vo)) { 2819 gclog_or_tty->print_cr("Root location "PTR_FORMAT" " 2820 "points to dead obj "PTR_FORMAT, p, (void*) obj); 2821 if (_vo == VerifyOption_G1UseMarkWord) { 2822 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark())); 2823 } 2824 obj->print_on(gclog_or_tty); 2825 _failures = true; 2826 } 2827 } 2828 } 2829 2830 void do_oop(oop* p) { do_oop_nv(p); } 2831 void do_oop(narrowOop* p) { do_oop_nv(p); } 2832 }; 2833 2834 class G1VerifyCodeRootOopClosure: public OopClosure { 2835 G1CollectedHeap* _g1h; 2836 OopClosure* _root_cl; 2837 nmethod* _nm; 2838 VerifyOption _vo; 2839 bool _failures; 2840 2841 template <class T> void do_oop_work(T* p) { 2842 // First verify that this root is live 2843 _root_cl->do_oop(p); 2844 2845 if (!G1VerifyHeapRegionCodeRoots) { 2846 // We're not verifying the code roots attached to heap region. 2847 return; 2848 } 2849 2850 // Don't check the code roots during marking verification in a full GC 2851 if (_vo == VerifyOption_G1UseMarkWord) { 2852 return; 2853 } 2854 2855 // Now verify that the current nmethod (which contains p) is 2856 // in the code root list of the heap region containing the 2857 // object referenced by p. 2858 2859 T heap_oop = oopDesc::load_heap_oop(p); 2860 if (!oopDesc::is_null(heap_oop)) { 2861 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 2862 2863 // Now fetch the region containing the object 2864 HeapRegion* hr = _g1h->heap_region_containing(obj); 2865 HeapRegionRemSet* hrrs = hr->rem_set(); 2866 // Verify that the strong code root list for this region 2867 // contains the nmethod 2868 if (!hrrs->strong_code_roots_list_contains(_nm)) { 2869 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" " 2870 "from nmethod "PTR_FORMAT" not in strong " 2871 "code roots for region ["PTR_FORMAT","PTR_FORMAT")", 2872 p, _nm, hr->bottom(), hr->end()); 2873 _failures = true; 2874 } 2875 } 2876 } 2877 2878 public: 2879 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo): 2880 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {} 2881 2882 void do_oop(oop* p) { do_oop_work(p); } 2883 void do_oop(narrowOop* p) { do_oop_work(p); } 2884 2885 void set_nmethod(nmethod* nm) { _nm = nm; } 2886 bool failures() { return _failures; } 2887 }; 2888 2889 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure { 2890 G1VerifyCodeRootOopClosure* _oop_cl; 2891 2892 public: 2893 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl): 2894 _oop_cl(oop_cl) {} 2895 2896 void do_code_blob(CodeBlob* cb) { 2897 nmethod* nm = cb->as_nmethod_or_null(); 2898 if (nm != NULL) { 2899 _oop_cl->set_nmethod(nm); 2900 nm->oops_do(_oop_cl); 2901 } 2902 } 2903 }; 2904 2905 class YoungRefCounterClosure : public OopClosure { 2906 G1CollectedHeap* _g1h; 2907 int _count; 2908 public: 2909 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {} 2910 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } } 2911 void do_oop(narrowOop* p) { ShouldNotReachHere(); } 2912 2913 int count() { return _count; } 2914 void reset_count() { _count = 0; }; 2915 }; 2916 2917 class VerifyKlassClosure: public KlassClosure { 2918 YoungRefCounterClosure _young_ref_counter_closure; 2919 OopClosure *_oop_closure; 2920 public: 2921 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {} 2922 void do_klass(Klass* k) { 2923 k->oops_do(_oop_closure); 2924 2925 _young_ref_counter_closure.reset_count(); 2926 k->oops_do(&_young_ref_counter_closure); 2927 if (_young_ref_counter_closure.count() > 0) { 2928 guarantee(k->has_modified_oops(), err_msg("Klass " PTR_FORMAT ", has young refs but is not dirty.", k)); 2929 } 2930 } 2931 }; 2932 2933 class VerifyLivenessOopClosure: public OopClosure { 2934 G1CollectedHeap* _g1h; 2935 VerifyOption _vo; 2936 public: 2937 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo): 2938 _g1h(g1h), _vo(vo) 2939 { } 2940 void do_oop(narrowOop *p) { do_oop_work(p); } 2941 void do_oop( oop *p) { do_oop_work(p); } 2942 2943 template <class T> void do_oop_work(T *p) { 2944 oop obj = oopDesc::load_decode_heap_oop(p); 2945 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo), 2946 "Dead object referenced by a not dead object"); 2947 } 2948 }; 2949 2950 class VerifyObjsInRegionClosure: public ObjectClosure { 2951 private: 2952 G1CollectedHeap* _g1h; 2953 size_t _live_bytes; 2954 HeapRegion *_hr; 2955 VerifyOption _vo; 2956 public: 2957 // _vo == UsePrevMarking -> use "prev" marking information, 2958 // _vo == UseNextMarking -> use "next" marking information, 2959 // _vo == UseMarkWord -> use mark word from object header. 2960 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo) 2961 : _live_bytes(0), _hr(hr), _vo(vo) { 2962 _g1h = G1CollectedHeap::heap(); 2963 } 2964 void do_object(oop o) { 2965 VerifyLivenessOopClosure isLive(_g1h, _vo); 2966 assert(o != NULL, "Huh?"); 2967 if (!_g1h->is_obj_dead_cond(o, _vo)) { 2968 // If the object is alive according to the mark word, 2969 // then verify that the marking information agrees. 2970 // Note we can't verify the contra-positive of the 2971 // above: if the object is dead (according to the mark 2972 // word), it may not be marked, or may have been marked 2973 // but has since became dead, or may have been allocated 2974 // since the last marking. 2975 if (_vo == VerifyOption_G1UseMarkWord) { 2976 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch"); 2977 } 2978 2979 o->oop_iterate_no_header(&isLive); 2980 if (!_hr->obj_allocated_since_prev_marking(o)) { 2981 size_t obj_size = o->size(); // Make sure we don't overflow 2982 _live_bytes += (obj_size * HeapWordSize); 2983 } 2984 } 2985 } 2986 size_t live_bytes() { return _live_bytes; } 2987 }; 2988 2989 class PrintObjsInRegionClosure : public ObjectClosure { 2990 HeapRegion *_hr; 2991 G1CollectedHeap *_g1; 2992 public: 2993 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) { 2994 _g1 = G1CollectedHeap::heap(); 2995 }; 2996 2997 void do_object(oop o) { 2998 if (o != NULL) { 2999 HeapWord *start = (HeapWord *) o; 3000 size_t word_sz = o->size(); 3001 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT 3002 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n", 3003 (void*) o, word_sz, 3004 _g1->isMarkedPrev(o), 3005 _g1->isMarkedNext(o), 3006 _hr->obj_allocated_since_prev_marking(o)); 3007 HeapWord *end = start + word_sz; 3008 HeapWord *cur; 3009 int *val; 3010 for (cur = start; cur < end; cur++) { 3011 val = (int *) cur; 3012 gclog_or_tty->print("\t "PTR_FORMAT":%d\n", val, *val); 3013 } 3014 } 3015 } 3016 }; 3017 3018 class VerifyRegionClosure: public HeapRegionClosure { 3019 private: 3020 bool _par; 3021 VerifyOption _vo; 3022 bool _failures; 3023 public: 3024 // _vo == UsePrevMarking -> use "prev" marking information, 3025 // _vo == UseNextMarking -> use "next" marking information, 3026 // _vo == UseMarkWord -> use mark word from object header. 3027 VerifyRegionClosure(bool par, VerifyOption vo) 3028 : _par(par), 3029 _vo(vo), 3030 _failures(false) {} 3031 3032 bool failures() { 3033 return _failures; 3034 } 3035 3036 bool doHeapRegion(HeapRegion* r) { 3037 if (!r->is_continues_humongous()) { 3038 bool failures = false; 3039 r->verify(_vo, &failures); 3040 if (failures) { 3041 _failures = true; 3042 } else { 3043 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo); 3044 r->object_iterate(¬_dead_yet_cl); 3045 if (_vo != VerifyOption_G1UseNextMarking) { 3046 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) { 3047 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] " 3048 "max_live_bytes "SIZE_FORMAT" " 3049 "< calculated "SIZE_FORMAT, 3050 r->bottom(), r->end(), 3051 r->max_live_bytes(), 3052 not_dead_yet_cl.live_bytes()); 3053 _failures = true; 3054 } 3055 } else { 3056 // When vo == UseNextMarking we cannot currently do a sanity 3057 // check on the live bytes as the calculation has not been 3058 // finalized yet. 3059 } 3060 } 3061 } 3062 return false; // stop the region iteration if we hit a failure 3063 } 3064 }; 3065 3066 // This is the task used for parallel verification of the heap regions 3067 3068 class G1ParVerifyTask: public AbstractGangTask { 3069 private: 3070 G1CollectedHeap* _g1h; 3071 VerifyOption _vo; 3072 bool _failures; 3073 HeapRegionClaimer _hrclaimer; 3074 3075 public: 3076 // _vo == UsePrevMarking -> use "prev" marking information, 3077 // _vo == UseNextMarking -> use "next" marking information, 3078 // _vo == UseMarkWord -> use mark word from object header. 3079 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) : 3080 AbstractGangTask("Parallel verify task"), 3081 _g1h(g1h), 3082 _vo(vo), 3083 _failures(false), 3084 _hrclaimer(g1h->workers()->active_workers()) {} 3085 3086 bool failures() { 3087 return _failures; 3088 } 3089 3090 void work(uint worker_id) { 3091 HandleMark hm; 3092 VerifyRegionClosure blk(true, _vo); 3093 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer); 3094 if (blk.failures()) { 3095 _failures = true; 3096 } 3097 } 3098 }; 3099 3100 void G1CollectedHeap::verify(bool silent, VerifyOption vo) { 3101 if (SafepointSynchronize::is_at_safepoint()) { 3102 assert(Thread::current()->is_VM_thread(), 3103 "Expected to be executed serially by the VM thread at this point"); 3104 3105 if (!silent) { gclog_or_tty->print("Roots "); } 3106 VerifyRootsClosure rootsCl(vo); 3107 VerifyKlassClosure klassCl(this, &rootsCl); 3108 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false); 3109 3110 // We apply the relevant closures to all the oops in the 3111 // system dictionary, class loader data graph, the string table 3112 // and the nmethods in the code cache. 3113 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo); 3114 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl); 3115 3116 process_all_roots(true, // activate StrongRootsScope 3117 SO_AllCodeCache, // roots scanning options 3118 &rootsCl, 3119 &cldCl, 3120 &blobsCl); 3121 3122 bool failures = rootsCl.failures() || codeRootsCl.failures(); 3123 3124 if (vo != VerifyOption_G1UseMarkWord) { 3125 // If we're verifying during a full GC then the region sets 3126 // will have been torn down at the start of the GC. Therefore 3127 // verifying the region sets will fail. So we only verify 3128 // the region sets when not in a full GC. 3129 if (!silent) { gclog_or_tty->print("HeapRegionSets "); } 3130 verify_region_sets(); 3131 } 3132 3133 if (!silent) { gclog_or_tty->print("HeapRegions "); } 3134 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) { 3135 3136 G1ParVerifyTask task(this, vo); 3137 assert(UseDynamicNumberOfGCThreads || 3138 workers()->active_workers() == workers()->total_workers(), 3139 "If not dynamic should be using all the workers"); 3140 int n_workers = workers()->active_workers(); 3141 set_par_threads(n_workers); 3142 workers()->run_task(&task); 3143 set_par_threads(0); 3144 if (task.failures()) { 3145 failures = true; 3146 } 3147 3148 } else { 3149 VerifyRegionClosure blk(false, vo); 3150 heap_region_iterate(&blk); 3151 if (blk.failures()) { 3152 failures = true; 3153 } 3154 } 3155 3156 if (G1StringDedup::is_enabled()) { 3157 if (!silent) gclog_or_tty->print("StrDedup "); 3158 G1StringDedup::verify(); 3159 } 3160 3161 if (failures) { 3162 gclog_or_tty->print_cr("Heap:"); 3163 // It helps to have the per-region information in the output to 3164 // help us track down what went wrong. This is why we call 3165 // print_extended_on() instead of print_on(). 3166 print_extended_on(gclog_or_tty); 3167 gclog_or_tty->cr(); 3168 #ifndef PRODUCT 3169 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) { 3170 concurrent_mark()->print_reachable("at-verification-failure", 3171 vo, false /* all */); 3172 } 3173 #endif 3174 gclog_or_tty->flush(); 3175 } 3176 guarantee(!failures, "there should not have been any failures"); 3177 } else { 3178 if (!silent) { 3179 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet"); 3180 if (G1StringDedup::is_enabled()) { 3181 gclog_or_tty->print(", StrDedup"); 3182 } 3183 gclog_or_tty->print(") "); 3184 } 3185 } 3186 } 3187 3188 void G1CollectedHeap::verify(bool silent) { 3189 verify(silent, VerifyOption_G1UsePrevMarking); 3190 } 3191 3192 double G1CollectedHeap::verify(bool guard, const char* msg) { 3193 double verify_time_ms = 0.0; 3194 3195 if (guard && total_collections() >= VerifyGCStartAt) { 3196 double verify_start = os::elapsedTime(); 3197 HandleMark hm; // Discard invalid handles created during verification 3198 prepare_for_verify(); 3199 Universe::verify(VerifyOption_G1UsePrevMarking, msg); 3200 verify_time_ms = (os::elapsedTime() - verify_start) * 1000; 3201 } 3202 3203 return verify_time_ms; 3204 } 3205 3206 void G1CollectedHeap::verify_before_gc() { 3207 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:"); 3208 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms); 3209 } 3210 3211 void G1CollectedHeap::verify_after_gc() { 3212 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:"); 3213 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms); 3214 } 3215 3216 class PrintRegionClosure: public HeapRegionClosure { 3217 outputStream* _st; 3218 public: 3219 PrintRegionClosure(outputStream* st) : _st(st) {} 3220 bool doHeapRegion(HeapRegion* r) { 3221 r->print_on(_st); 3222 return false; 3223 } 3224 }; 3225 3226 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 3227 const HeapRegion* hr, 3228 const VerifyOption vo) const { 3229 switch (vo) { 3230 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); 3231 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); 3232 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked(); 3233 default: ShouldNotReachHere(); 3234 } 3235 return false; // keep some compilers happy 3236 } 3237 3238 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 3239 const VerifyOption vo) const { 3240 switch (vo) { 3241 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); 3242 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); 3243 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked(); 3244 default: ShouldNotReachHere(); 3245 } 3246 return false; // keep some compilers happy 3247 } 3248 3249 void G1CollectedHeap::print_on(outputStream* st) const { 3250 st->print(" %-20s", "garbage-first heap"); 3251 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 3252 capacity()/K, used_unlocked()/K); 3253 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")", 3254 _hrm.reserved().start(), 3255 _hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords, 3256 _hrm.reserved().end()); 3257 st->cr(); 3258 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); 3259 uint young_regions = _young_list->length(); 3260 st->print("%u young (" SIZE_FORMAT "K), ", young_regions, 3261 (size_t) young_regions * HeapRegion::GrainBytes / K); 3262 uint survivor_regions = g1_policy()->recorded_survivor_regions(); 3263 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, 3264 (size_t) survivor_regions * HeapRegion::GrainBytes / K); 3265 st->cr(); 3266 MetaspaceAux::print_on(st); 3267 } 3268 3269 void G1CollectedHeap::print_extended_on(outputStream* st) const { 3270 print_on(st); 3271 3272 // Print the per-region information. 3273 st->cr(); 3274 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), " 3275 "HS=humongous(starts), HC=humongous(continues), " 3276 "CS=collection set, F=free, TS=gc time stamp, " 3277 "PTAMS=previous top-at-mark-start, " 3278 "NTAMS=next top-at-mark-start)"); 3279 PrintRegionClosure blk(st); 3280 heap_region_iterate(&blk); 3281 } 3282 3283 void G1CollectedHeap::print_on_error(outputStream* st) const { 3284 this->CollectedHeap::print_on_error(st); 3285 3286 if (_cm != NULL) { 3287 st->cr(); 3288 _cm->print_on_error(st); 3289 } 3290 } 3291 3292 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const { 3293 workers()->print_worker_threads_on(st); 3294 _cmThread->print_on(st); 3295 st->cr(); 3296 _cm->print_worker_threads_on(st); 3297 _cg1r->print_worker_threads_on(st); 3298 if (G1StringDedup::is_enabled()) { 3299 G1StringDedup::print_worker_threads_on(st); 3300 } 3301 } 3302 3303 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { 3304 workers()->threads_do(tc); 3305 tc->do_thread(_cmThread); 3306 _cg1r->threads_do(tc); 3307 if (G1StringDedup::is_enabled()) { 3308 G1StringDedup::threads_do(tc); 3309 } 3310 } 3311 3312 void G1CollectedHeap::print_tracing_info() const { 3313 // We'll overload this to mean "trace GC pause statistics." 3314 if (TraceYoungGenTime || TraceOldGenTime) { 3315 // The "G1CollectorPolicy" is keeping track of these stats, so delegate 3316 // to that. 3317 g1_policy()->print_tracing_info(); 3318 } 3319 if (G1SummarizeRSetStats) { 3320 g1_rem_set()->print_summary_info(); 3321 } 3322 if (G1SummarizeConcMark) { 3323 concurrent_mark()->print_summary_info(); 3324 } 3325 g1_policy()->print_yg_surv_rate_info(); 3326 SpecializationStats::print(); 3327 } 3328 3329 #ifndef PRODUCT 3330 // Helpful for debugging RSet issues. 3331 3332 class PrintRSetsClosure : public HeapRegionClosure { 3333 private: 3334 const char* _msg; 3335 size_t _occupied_sum; 3336 3337 public: 3338 bool doHeapRegion(HeapRegion* r) { 3339 HeapRegionRemSet* hrrs = r->rem_set(); 3340 size_t occupied = hrrs->occupied(); 3341 _occupied_sum += occupied; 3342 3343 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT, 3344 HR_FORMAT_PARAMS(r)); 3345 if (occupied == 0) { 3346 gclog_or_tty->print_cr(" RSet is empty"); 3347 } else { 3348 hrrs->print(); 3349 } 3350 gclog_or_tty->print_cr("----------"); 3351 return false; 3352 } 3353 3354 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { 3355 gclog_or_tty->cr(); 3356 gclog_or_tty->print_cr("========================================"); 3357 gclog_or_tty->print_cr("%s", msg); 3358 gclog_or_tty->cr(); 3359 } 3360 3361 ~PrintRSetsClosure() { 3362 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum); 3363 gclog_or_tty->print_cr("========================================"); 3364 gclog_or_tty->cr(); 3365 } 3366 }; 3367 3368 void G1CollectedHeap::print_cset_rsets() { 3369 PrintRSetsClosure cl("Printing CSet RSets"); 3370 collection_set_iterate(&cl); 3371 } 3372 3373 void G1CollectedHeap::print_all_rsets() { 3374 PrintRSetsClosure cl("Printing All RSets");; 3375 heap_region_iterate(&cl); 3376 } 3377 #endif // PRODUCT 3378 3379 G1CollectedHeap* G1CollectedHeap::heap() { 3380 assert(_sh->kind() == CollectedHeap::G1CollectedHeap, 3381 "not a garbage-first heap"); 3382 return _g1h; 3383 } 3384 3385 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) { 3386 // always_do_update_barrier = false; 3387 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 3388 // Fill TLAB's and such 3389 accumulate_statistics_all_tlabs(); 3390 ensure_parsability(true); 3391 3392 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) && 3393 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) { 3394 g1_rem_set()->print_periodic_summary_info("Before GC RS summary"); 3395 } 3396 } 3397 3398 void G1CollectedHeap::gc_epilogue(bool full) { 3399 3400 if (G1SummarizeRSetStats && 3401 (G1SummarizeRSetStatsPeriod > 0) && 3402 // we are at the end of the GC. Total collections has already been increased. 3403 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) { 3404 g1_rem_set()->print_periodic_summary_info("After GC RS summary"); 3405 } 3406 3407 // FIXME: what is this about? 3408 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" 3409 // is set. 3410 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(), 3411 "derived pointer present")); 3412 // always_do_update_barrier = true; 3413 3414 resize_all_tlabs(); 3415 allocation_context_stats().update(full); 3416 3417 // We have just completed a GC. Update the soft reference 3418 // policy with the new heap occupancy 3419 Universe::update_heap_info_at_gc(); 3420 } 3421 3422 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, 3423 unsigned int gc_count_before, 3424 bool* succeeded, 3425 GCCause::Cause gc_cause) { 3426 assert_heap_not_locked_and_not_at_safepoint(); 3427 g1_policy()->record_stop_world_start(); 3428 VM_G1IncCollectionPause op(gc_count_before, 3429 word_size, 3430 false, /* should_initiate_conc_mark */ 3431 g1_policy()->max_pause_time_ms(), 3432 gc_cause); 3433 3434 op.set_allocation_context(AllocationContext::current()); 3435 VMThread::execute(&op); 3436 3437 HeapWord* result = op.result(); 3438 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded(); 3439 assert(result == NULL || ret_succeeded, 3440 "the result should be NULL if the VM did not succeed"); 3441 *succeeded = ret_succeeded; 3442 3443 assert_heap_not_locked(); 3444 return result; 3445 } 3446 3447 void 3448 G1CollectedHeap::doConcurrentMark() { 3449 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); 3450 if (!_cmThread->in_progress()) { 3451 _cmThread->set_started(); 3452 CGC_lock->notify(); 3453 } 3454 } 3455 3456 size_t G1CollectedHeap::pending_card_num() { 3457 size_t extra_cards = 0; 3458 JavaThread *curr = Threads::first(); 3459 while (curr != NULL) { 3460 DirtyCardQueue& dcq = curr->dirty_card_queue(); 3461 extra_cards += dcq.size(); 3462 curr = curr->next(); 3463 } 3464 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 3465 size_t buffer_size = dcqs.buffer_size(); 3466 size_t buffer_num = dcqs.completed_buffers_num(); 3467 3468 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes 3469 // in bytes - not the number of 'entries'. We need to convert 3470 // into a number of cards. 3471 return (buffer_size * buffer_num + extra_cards) / oopSize; 3472 } 3473 3474 size_t G1CollectedHeap::cards_scanned() { 3475 return g1_rem_set()->cardsScanned(); 3476 } 3477 3478 bool G1CollectedHeap::humongous_region_is_always_live(uint index) { 3479 HeapRegion* region = region_at(index); 3480 assert(region->is_starts_humongous(), "Must start a humongous object"); 3481 return oop(region->bottom())->is_objArray() || !region->rem_set()->is_empty(); 3482 } 3483 3484 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure { 3485 private: 3486 size_t _total_humongous; 3487 size_t _candidate_humongous; 3488 3489 DirtyCardQueue _dcq; 3490 3491 bool humongous_region_is_candidate(uint index) { 3492 HeapRegion* region = G1CollectedHeap::heap()->region_at(index); 3493 assert(region->is_starts_humongous(), "Must start a humongous object"); 3494 HeapRegionRemSet* const rset = region->rem_set(); 3495 bool const allow_stale_refs = G1EagerReclaimHumongousObjectsWithStaleRefs; 3496 return !oop(region->bottom())->is_objArray() && 3497 ((allow_stale_refs && rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)) || 3498 (!allow_stale_refs && rset->is_empty())); 3499 } 3500 3501 public: 3502 RegisterHumongousWithInCSetFastTestClosure() 3503 : _total_humongous(0), 3504 _candidate_humongous(0), 3505 _dcq(&JavaThread::dirty_card_queue_set()) { 3506 } 3507 3508 virtual bool doHeapRegion(HeapRegion* r) { 3509 if (!r->is_starts_humongous()) { 3510 return false; 3511 } 3512 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 3513 3514 uint region_idx = r->hrm_index(); 3515 bool is_candidate = humongous_region_is_candidate(region_idx); 3516 // Is_candidate already filters out humongous object with large remembered sets. 3517 // If we have a humongous object with a few remembered sets, we simply flush these 3518 // remembered set entries into the DCQS. That will result in automatic 3519 // re-evaluation of their remembered set entries during the following evacuation 3520 // phase. 3521 if (is_candidate) { 3522 if (!r->rem_set()->is_empty()) { 3523 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries), 3524 "Found a not-small remembered set here. This is inconsistent with previous assumptions."); 3525 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set(); 3526 HeapRegionRemSetIterator hrrs(r->rem_set()); 3527 size_t card_index; 3528 while (hrrs.has_next(card_index)) { 3529 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index); 3530 if (*card_ptr != CardTableModRefBS::dirty_card_val()) { 3531 *card_ptr = CardTableModRefBS::dirty_card_val(); 3532 _dcq.enqueue(card_ptr); 3533 } 3534 } 3535 r->rem_set()->clear_locked(); 3536 } 3537 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty."); 3538 g1h->register_humongous_region_with_in_cset_fast_test(region_idx); 3539 _candidate_humongous++; 3540 } 3541 _total_humongous++; 3542 3543 return false; 3544 } 3545 3546 size_t total_humongous() const { return _total_humongous; } 3547 size_t candidate_humongous() const { return _candidate_humongous; } 3548 3549 void flush_rem_set_entries() { _dcq.flush(); } 3550 }; 3551 3552 void G1CollectedHeap::register_humongous_regions_with_in_cset_fast_test() { 3553 if (!G1EagerReclaimHumongousObjects) { 3554 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0); 3555 return; 3556 } 3557 double time = os::elapsed_counter(); 3558 3559 RegisterHumongousWithInCSetFastTestClosure cl; 3560 heap_region_iterate(&cl); 3561 3562 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0; 3563 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time, 3564 cl.total_humongous(), 3565 cl.candidate_humongous()); 3566 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0; 3567 3568 if (_has_humongous_reclaim_candidates || G1TraceEagerReclaimHumongousObjects) { 3569 clear_humongous_is_live_table(); 3570 } 3571 3572 // Finally flush all remembered set entries to re-check into the global DCQS. 3573 cl.flush_rem_set_entries(); 3574 } 3575 3576 void 3577 G1CollectedHeap::setup_surviving_young_words() { 3578 assert(_surviving_young_words == NULL, "pre-condition"); 3579 uint array_length = g1_policy()->young_cset_region_length(); 3580 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC); 3581 if (_surviving_young_words == NULL) { 3582 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR, 3583 "Not enough space for young surv words summary."); 3584 } 3585 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t)); 3586 #ifdef ASSERT 3587 for (uint i = 0; i < array_length; ++i) { 3588 assert( _surviving_young_words[i] == 0, "memset above" ); 3589 } 3590 #endif // !ASSERT 3591 } 3592 3593 void 3594 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) { 3595 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); 3596 uint array_length = g1_policy()->young_cset_region_length(); 3597 for (uint i = 0; i < array_length; ++i) { 3598 _surviving_young_words[i] += surv_young_words[i]; 3599 } 3600 } 3601 3602 void 3603 G1CollectedHeap::cleanup_surviving_young_words() { 3604 guarantee( _surviving_young_words != NULL, "pre-condition" ); 3605 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words); 3606 _surviving_young_words = NULL; 3607 } 3608 3609 #ifdef ASSERT 3610 class VerifyCSetClosure: public HeapRegionClosure { 3611 public: 3612 bool doHeapRegion(HeapRegion* hr) { 3613 // Here we check that the CSet region's RSet is ready for parallel 3614 // iteration. The fields that we'll verify are only manipulated 3615 // when the region is part of a CSet and is collected. Afterwards, 3616 // we reset these fields when we clear the region's RSet (when the 3617 // region is freed) so they are ready when the region is 3618 // re-allocated. The only exception to this is if there's an 3619 // evacuation failure and instead of freeing the region we leave 3620 // it in the heap. In that case, we reset these fields during 3621 // evacuation failure handling. 3622 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification"); 3623 3624 // Here's a good place to add any other checks we'd like to 3625 // perform on CSet regions. 3626 return false; 3627 } 3628 }; 3629 #endif // ASSERT 3630 3631 #if TASKQUEUE_STATS 3632 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) { 3633 st->print_raw_cr("GC Task Stats"); 3634 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); 3635 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); 3636 } 3637 3638 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const { 3639 print_taskqueue_stats_hdr(st); 3640 3641 TaskQueueStats totals; 3642 const int n = workers()->total_workers(); 3643 for (int i = 0; i < n; ++i) { 3644 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr(); 3645 totals += task_queue(i)->stats; 3646 } 3647 st->print_raw("tot "); totals.print(st); st->cr(); 3648 3649 DEBUG_ONLY(totals.verify()); 3650 } 3651 3652 void G1CollectedHeap::reset_taskqueue_stats() { 3653 const int n = workers()->total_workers(); 3654 for (int i = 0; i < n; ++i) { 3655 task_queue(i)->stats.reset(); 3656 } 3657 } 3658 #endif // TASKQUEUE_STATS 3659 3660 void G1CollectedHeap::log_gc_header() { 3661 if (!G1Log::fine()) { 3662 return; 3663 } 3664 3665 gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id()); 3666 3667 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause()) 3668 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)") 3669 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : ""); 3670 3671 gclog_or_tty->print("[%s", (const char*)gc_cause_str); 3672 } 3673 3674 void G1CollectedHeap::log_gc_footer(double pause_time_sec) { 3675 if (!G1Log::fine()) { 3676 return; 3677 } 3678 3679 if (G1Log::finer()) { 3680 if (evacuation_failed()) { 3681 gclog_or_tty->print(" (to-space exhausted)"); 3682 } 3683 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec); 3684 g1_policy()->phase_times()->note_gc_end(); 3685 g1_policy()->phase_times()->print(pause_time_sec); 3686 g1_policy()->print_detailed_heap_transition(); 3687 } else { 3688 if (evacuation_failed()) { 3689 gclog_or_tty->print("--"); 3690 } 3691 g1_policy()->print_heap_transition(); 3692 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec); 3693 } 3694 gclog_or_tty->flush(); 3695 } 3696 3697 bool 3698 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { 3699 assert_at_safepoint(true /* should_be_vm_thread */); 3700 guarantee(!is_gc_active(), "collection is not reentrant"); 3701 3702 if (GC_locker::check_active_before_gc()) { 3703 return false; 3704 } 3705 3706 _gc_timer_stw->register_gc_start(); 3707 3708 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start()); 3709 3710 SvcGCMarker sgcm(SvcGCMarker::MINOR); 3711 ResourceMark rm; 3712 3713 print_heap_before_gc(); 3714 trace_heap_before_gc(_gc_tracer_stw); 3715 3716 verify_region_sets_optional(); 3717 verify_dirty_young_regions(); 3718 3719 // This call will decide whether this pause is an initial-mark 3720 // pause. If it is, during_initial_mark_pause() will return true 3721 // for the duration of this pause. 3722 g1_policy()->decide_on_conc_mark_initiation(); 3723 3724 // We do not allow initial-mark to be piggy-backed on a mixed GC. 3725 assert(!g1_policy()->during_initial_mark_pause() || 3726 g1_policy()->gcs_are_young(), "sanity"); 3727 3728 // We also do not allow mixed GCs during marking. 3729 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity"); 3730 3731 // Record whether this pause is an initial mark. When the current 3732 // thread has completed its logging output and it's safe to signal 3733 // the CM thread, the flag's value in the policy has been reset. 3734 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause(); 3735 3736 // Inner scope for scope based logging, timers, and stats collection 3737 { 3738 EvacuationInfo evacuation_info; 3739 3740 if (g1_policy()->during_initial_mark_pause()) { 3741 // We are about to start a marking cycle, so we increment the 3742 // full collection counter. 3743 increment_old_marking_cycles_started(); 3744 register_concurrent_cycle_start(_gc_timer_stw->gc_start()); 3745 } 3746 3747 _gc_tracer_stw->report_yc_type(yc_type()); 3748 3749 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty); 3750 3751 int active_workers = workers()->active_workers(); 3752 double pause_start_sec = os::elapsedTime(); 3753 g1_policy()->phase_times()->note_gc_start(active_workers); 3754 log_gc_header(); 3755 3756 TraceCollectorStats tcs(g1mm()->incremental_collection_counters()); 3757 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause()); 3758 3759 // If the secondary_free_list is not empty, append it to the 3760 // free_list. No need to wait for the cleanup operation to finish; 3761 // the region allocation code will check the secondary_free_list 3762 // and wait if necessary. If the G1StressConcRegionFreeing flag is 3763 // set, skip this step so that the region allocation code has to 3764 // get entries from the secondary_free_list. 3765 if (!G1StressConcRegionFreeing) { 3766 append_secondary_free_list_if_not_empty_with_lock(); 3767 } 3768 3769 assert(check_young_list_well_formed(), "young list should be well formed"); 3770 3771 // Don't dynamically change the number of GC threads this early. A value of 3772 // 0 is used to indicate serial work. When parallel work is done, 3773 // it will be set. 3774 3775 { // Call to jvmpi::post_class_unload_events must occur outside of active GC 3776 IsGCActiveMark x; 3777 3778 gc_prologue(false); 3779 increment_total_collections(false /* full gc */); 3780 increment_gc_time_stamp(); 3781 3782 verify_before_gc(); 3783 3784 check_bitmaps("GC Start"); 3785 3786 COMPILER2_PRESENT(DerivedPointerTable::clear()); 3787 3788 // Please see comment in g1CollectedHeap.hpp and 3789 // G1CollectedHeap::ref_processing_init() to see how 3790 // reference processing currently works in G1. 3791 3792 // Enable discovery in the STW reference processor 3793 ref_processor_stw()->enable_discovery(); 3794 3795 { 3796 // We want to temporarily turn off discovery by the 3797 // CM ref processor, if necessary, and turn it back on 3798 // on again later if we do. Using a scoped 3799 // NoRefDiscovery object will do this. 3800 NoRefDiscovery no_cm_discovery(ref_processor_cm()); 3801 3802 // Forget the current alloc region (we might even choose it to be part 3803 // of the collection set!). 3804 _allocator->release_mutator_alloc_region(); 3805 3806 // We should call this after we retire the mutator alloc 3807 // region(s) so that all the ALLOC / RETIRE events are generated 3808 // before the start GC event. 3809 _hr_printer.start_gc(false /* full */, (size_t) total_collections()); 3810 3811 // This timing is only used by the ergonomics to handle our pause target. 3812 // It is unclear why this should not include the full pause. We will 3813 // investigate this in CR 7178365. 3814 // 3815 // Preserving the old comment here if that helps the investigation: 3816 // 3817 // The elapsed time induced by the start time below deliberately elides 3818 // the possible verification above. 3819 double sample_start_time_sec = os::elapsedTime(); 3820 3821 #if YOUNG_LIST_VERBOSE 3822 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:"); 3823 _young_list->print(); 3824 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 3825 #endif // YOUNG_LIST_VERBOSE 3826 3827 g1_policy()->record_collection_pause_start(sample_start_time_sec); 3828 3829 double scan_wait_start = os::elapsedTime(); 3830 // We have to wait until the CM threads finish scanning the 3831 // root regions as it's the only way to ensure that all the 3832 // objects on them have been correctly scanned before we start 3833 // moving them during the GC. 3834 bool waited = _cm->root_regions()->wait_until_scan_finished(); 3835 double wait_time_ms = 0.0; 3836 if (waited) { 3837 double scan_wait_end = os::elapsedTime(); 3838 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0; 3839 } 3840 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms); 3841 3842 #if YOUNG_LIST_VERBOSE 3843 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:"); 3844 _young_list->print(); 3845 #endif // YOUNG_LIST_VERBOSE 3846 3847 if (g1_policy()->during_initial_mark_pause()) { 3848 concurrent_mark()->checkpointRootsInitialPre(); 3849 } 3850 3851 #if YOUNG_LIST_VERBOSE 3852 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:"); 3853 _young_list->print(); 3854 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 3855 #endif // YOUNG_LIST_VERBOSE 3856 3857 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info); 3858 3859 register_humongous_regions_with_in_cset_fast_test(); 3860 3861 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table."); 3862 3863 _cm->note_start_of_gc(); 3864 // We should not verify the per-thread SATB buffers given that 3865 // we have not filtered them yet (we'll do so during the 3866 // GC). We also call this after finalize_cset() to 3867 // ensure that the CSet has been finalized. 3868 _cm->verify_no_cset_oops(true /* verify_stacks */, 3869 true /* verify_enqueued_buffers */, 3870 false /* verify_thread_buffers */, 3871 true /* verify_fingers */); 3872 3873 if (_hr_printer.is_active()) { 3874 HeapRegion* hr = g1_policy()->collection_set(); 3875 while (hr != NULL) { 3876 _hr_printer.cset(hr); 3877 hr = hr->next_in_collection_set(); 3878 } 3879 } 3880 3881 #ifdef ASSERT 3882 VerifyCSetClosure cl; 3883 collection_set_iterate(&cl); 3884 #endif // ASSERT 3885 3886 setup_surviving_young_words(); 3887 3888 // Initialize the GC alloc regions. 3889 _allocator->init_gc_alloc_regions(evacuation_info); 3890 3891 // Actually do the work... 3892 evacuate_collection_set(evacuation_info); 3893 3894 // We do this to mainly verify the per-thread SATB buffers 3895 // (which have been filtered by now) since we didn't verify 3896 // them earlier. No point in re-checking the stacks / enqueued 3897 // buffers given that the CSet has not changed since last time 3898 // we checked. 3899 _cm->verify_no_cset_oops(false /* verify_stacks */, 3900 false /* verify_enqueued_buffers */, 3901 true /* verify_thread_buffers */, 3902 true /* verify_fingers */); 3903 3904 free_collection_set(g1_policy()->collection_set(), evacuation_info); 3905 3906 eagerly_reclaim_humongous_regions(); 3907 3908 g1_policy()->clear_collection_set(); 3909 3910 cleanup_surviving_young_words(); 3911 3912 // Start a new incremental collection set for the next pause. 3913 g1_policy()->start_incremental_cset_building(); 3914 3915 clear_cset_fast_test(); 3916 3917 _young_list->reset_sampled_info(); 3918 3919 // Don't check the whole heap at this point as the 3920 // GC alloc regions from this pause have been tagged 3921 // as survivors and moved on to the survivor list. 3922 // Survivor regions will fail the !is_young() check. 3923 assert(check_young_list_empty(false /* check_heap */), 3924 "young list should be empty"); 3925 3926 #if YOUNG_LIST_VERBOSE 3927 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:"); 3928 _young_list->print(); 3929 #endif // YOUNG_LIST_VERBOSE 3930 3931 g1_policy()->record_survivor_regions(_young_list->survivor_length(), 3932 _young_list->first_survivor_region(), 3933 _young_list->last_survivor_region()); 3934 3935 _young_list->reset_auxilary_lists(); 3936 3937 if (evacuation_failed()) { 3938 _allocator->set_used(recalculate_used()); 3939 uint n_queues = MAX2((int)ParallelGCThreads, 1); 3940 for (uint i = 0; i < n_queues; i++) { 3941 if (_evacuation_failed_info_array[i].has_failed()) { 3942 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]); 3943 } 3944 } 3945 } else { 3946 // The "used" of the the collection set have already been subtracted 3947 // when they were freed. Add in the bytes evacuated. 3948 _allocator->increase_used(g1_policy()->bytes_copied_during_gc()); 3949 } 3950 3951 if (g1_policy()->during_initial_mark_pause()) { 3952 // We have to do this before we notify the CM threads that 3953 // they can start working to make sure that all the 3954 // appropriate initialization is done on the CM object. 3955 concurrent_mark()->checkpointRootsInitialPost(); 3956 set_marking_started(); 3957 // Note that we don't actually trigger the CM thread at 3958 // this point. We do that later when we're sure that 3959 // the current thread has completed its logging output. 3960 } 3961 3962 allocate_dummy_regions(); 3963 3964 #if YOUNG_LIST_VERBOSE 3965 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:"); 3966 _young_list->print(); 3967 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 3968 #endif // YOUNG_LIST_VERBOSE 3969 3970 _allocator->init_mutator_alloc_region(); 3971 3972 { 3973 size_t expand_bytes = g1_policy()->expansion_amount(); 3974 if (expand_bytes > 0) { 3975 size_t bytes_before = capacity(); 3976 // No need for an ergo verbose message here, 3977 // expansion_amount() does this when it returns a value > 0. 3978 if (!expand(expand_bytes)) { 3979 // We failed to expand the heap. Cannot do anything about it. 3980 } 3981 } 3982 } 3983 3984 // We redo the verification but now wrt to the new CSet which 3985 // has just got initialized after the previous CSet was freed. 3986 _cm->verify_no_cset_oops(true /* verify_stacks */, 3987 true /* verify_enqueued_buffers */, 3988 true /* verify_thread_buffers */, 3989 true /* verify_fingers */); 3990 _cm->note_end_of_gc(); 3991 3992 // This timing is only used by the ergonomics to handle our pause target. 3993 // It is unclear why this should not include the full pause. We will 3994 // investigate this in CR 7178365. 3995 double sample_end_time_sec = os::elapsedTime(); 3996 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; 3997 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info); 3998 3999 MemoryService::track_memory_usage(); 4000 4001 // In prepare_for_verify() below we'll need to scan the deferred 4002 // update buffers to bring the RSets up-to-date if 4003 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning 4004 // the update buffers we'll probably need to scan cards on the 4005 // regions we just allocated to (i.e., the GC alloc 4006 // regions). However, during the last GC we called 4007 // set_saved_mark() on all the GC alloc regions, so card 4008 // scanning might skip the [saved_mark_word()...top()] area of 4009 // those regions (i.e., the area we allocated objects into 4010 // during the last GC). But it shouldn't. Given that 4011 // saved_mark_word() is conditional on whether the GC time stamp 4012 // on the region is current or not, by incrementing the GC time 4013 // stamp here we invalidate all the GC time stamps on all the 4014 // regions and saved_mark_word() will simply return top() for 4015 // all the regions. This is a nicer way of ensuring this rather 4016 // than iterating over the regions and fixing them. In fact, the 4017 // GC time stamp increment here also ensures that 4018 // saved_mark_word() will return top() between pauses, i.e., 4019 // during concurrent refinement. So we don't need the 4020 // is_gc_active() check to decided which top to use when 4021 // scanning cards (see CR 7039627). 4022 increment_gc_time_stamp(); 4023 4024 verify_after_gc(); 4025 check_bitmaps("GC End"); 4026 4027 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 4028 ref_processor_stw()->verify_no_references_recorded(); 4029 4030 // CM reference discovery will be re-enabled if necessary. 4031 } 4032 4033 // We should do this after we potentially expand the heap so 4034 // that all the COMMIT events are generated before the end GC 4035 // event, and after we retire the GC alloc regions so that all 4036 // RETIRE events are generated before the end GC event. 4037 _hr_printer.end_gc(false /* full */, (size_t) total_collections()); 4038 4039 #ifdef TRACESPINNING 4040 ParallelTaskTerminator::print_termination_counts(); 4041 #endif 4042 4043 gc_epilogue(false); 4044 } 4045 4046 // Print the remainder of the GC log output. 4047 log_gc_footer(os::elapsedTime() - pause_start_sec); 4048 4049 // It is not yet to safe to tell the concurrent mark to 4050 // start as we have some optional output below. We don't want the 4051 // output from the concurrent mark thread interfering with this 4052 // logging output either. 4053 4054 _hrm.verify_optional(); 4055 verify_region_sets_optional(); 4056 4057 TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats()); 4058 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); 4059 4060 print_heap_after_gc(); 4061 trace_heap_after_gc(_gc_tracer_stw); 4062 4063 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 4064 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 4065 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 4066 // before any GC notifications are raised. 4067 g1mm()->update_sizes(); 4068 4069 _gc_tracer_stw->report_evacuation_info(&evacuation_info); 4070 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold()); 4071 _gc_timer_stw->register_gc_end(); 4072 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions()); 4073 } 4074 // It should now be safe to tell the concurrent mark thread to start 4075 // without its logging output interfering with the logging output 4076 // that came from the pause. 4077 4078 if (should_start_conc_mark) { 4079 // CAUTION: after the doConcurrentMark() call below, 4080 // the concurrent marking thread(s) could be running 4081 // concurrently with us. Make sure that anything after 4082 // this point does not assume that we are the only GC thread 4083 // running. Note: of course, the actual marking work will 4084 // not start until the safepoint itself is released in 4085 // SuspendibleThreadSet::desynchronize(). 4086 doConcurrentMark(); 4087 } 4088 4089 return true; 4090 } 4091 4092 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) { 4093 _drain_in_progress = false; 4094 set_evac_failure_closure(cl); 4095 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true); 4096 } 4097 4098 void G1CollectedHeap::finalize_for_evac_failure() { 4099 assert(_evac_failure_scan_stack != NULL && 4100 _evac_failure_scan_stack->length() == 0, 4101 "Postcondition"); 4102 assert(!_drain_in_progress, "Postcondition"); 4103 delete _evac_failure_scan_stack; 4104 _evac_failure_scan_stack = NULL; 4105 } 4106 4107 void G1CollectedHeap::remove_self_forwarding_pointers() { 4108 double remove_self_forwards_start = os::elapsedTime(); 4109 4110 set_par_threads(); 4111 G1ParRemoveSelfForwardPtrsTask rsfp_task(this); 4112 workers()->run_task(&rsfp_task); 4113 set_par_threads(0); 4114 4115 // Now restore saved marks, if any. 4116 assert(_objs_with_preserved_marks.size() == 4117 _preserved_marks_of_objs.size(), "Both or none."); 4118 while (!_objs_with_preserved_marks.is_empty()) { 4119 oop obj = _objs_with_preserved_marks.pop(); 4120 markOop m = _preserved_marks_of_objs.pop(); 4121 obj->set_mark(m); 4122 } 4123 _objs_with_preserved_marks.clear(true); 4124 _preserved_marks_of_objs.clear(true); 4125 4126 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0); 4127 } 4128 4129 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) { 4130 _evac_failure_scan_stack->push(obj); 4131 } 4132 4133 void G1CollectedHeap::drain_evac_failure_scan_stack() { 4134 assert(_evac_failure_scan_stack != NULL, "precondition"); 4135 4136 while (_evac_failure_scan_stack->length() > 0) { 4137 oop obj = _evac_failure_scan_stack->pop(); 4138 _evac_failure_closure->set_region(heap_region_containing(obj)); 4139 obj->oop_iterate_backwards(_evac_failure_closure); 4140 } 4141 } 4142 4143 oop 4144 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state, 4145 oop old) { 4146 assert(obj_in_cs(old), 4147 err_msg("obj: "PTR_FORMAT" should still be in the CSet", 4148 (HeapWord*) old)); 4149 markOop m = old->mark(); 4150 oop forward_ptr = old->forward_to_atomic(old); 4151 if (forward_ptr == NULL) { 4152 // Forward-to-self succeeded. 4153 assert(_par_scan_state != NULL, "par scan state"); 4154 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure(); 4155 uint queue_num = _par_scan_state->queue_num(); 4156 4157 _evacuation_failed = true; 4158 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size()); 4159 if (_evac_failure_closure != cl) { 4160 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag); 4161 assert(!_drain_in_progress, 4162 "Should only be true while someone holds the lock."); 4163 // Set the global evac-failure closure to the current thread's. 4164 assert(_evac_failure_closure == NULL, "Or locking has failed."); 4165 set_evac_failure_closure(cl); 4166 // Now do the common part. 4167 handle_evacuation_failure_common(old, m); 4168 // Reset to NULL. 4169 set_evac_failure_closure(NULL); 4170 } else { 4171 // The lock is already held, and this is recursive. 4172 assert(_drain_in_progress, "This should only be the recursive case."); 4173 handle_evacuation_failure_common(old, m); 4174 } 4175 return old; 4176 } else { 4177 // Forward-to-self failed. Either someone else managed to allocate 4178 // space for this object (old != forward_ptr) or they beat us in 4179 // self-forwarding it (old == forward_ptr). 4180 assert(old == forward_ptr || !obj_in_cs(forward_ptr), 4181 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" " 4182 "should not be in the CSet", 4183 (HeapWord*) old, (HeapWord*) forward_ptr)); 4184 return forward_ptr; 4185 } 4186 } 4187 4188 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) { 4189 preserve_mark_if_necessary(old, m); 4190 4191 HeapRegion* r = heap_region_containing(old); 4192 if (!r->evacuation_failed()) { 4193 r->set_evacuation_failed(true); 4194 _hr_printer.evac_failure(r); 4195 } 4196 4197 push_on_evac_failure_scan_stack(old); 4198 4199 if (!_drain_in_progress) { 4200 // prevent recursion in copy_to_survivor_space() 4201 _drain_in_progress = true; 4202 drain_evac_failure_scan_stack(); 4203 _drain_in_progress = false; 4204 } 4205 } 4206 4207 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) { 4208 assert(evacuation_failed(), "Oversaving!"); 4209 // We want to call the "for_promotion_failure" version only in the 4210 // case of a promotion failure. 4211 if (m->must_be_preserved_for_promotion_failure(obj)) { 4212 _objs_with_preserved_marks.push(obj); 4213 _preserved_marks_of_objs.push(m); 4214 } 4215 } 4216 4217 void G1ParCopyHelper::mark_object(oop obj) { 4218 assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet"); 4219 4220 // We know that the object is not moving so it's safe to read its size. 4221 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id); 4222 } 4223 4224 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) { 4225 assert(from_obj->is_forwarded(), "from obj should be forwarded"); 4226 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee"); 4227 assert(from_obj != to_obj, "should not be self-forwarded"); 4228 4229 assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet"); 4230 assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet"); 4231 4232 // The object might be in the process of being copied by another 4233 // worker so we cannot trust that its to-space image is 4234 // well-formed. So we have to read its size from its from-space 4235 // image which we know should not be changing. 4236 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id); 4237 } 4238 4239 template <class T> 4240 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) { 4241 if (_g1->heap_region_containing_raw(new_obj)->is_young()) { 4242 _scanned_klass->record_modified_oops(); 4243 } 4244 } 4245 4246 template <G1Barrier barrier, G1Mark do_mark_object> 4247 template <class T> 4248 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) { 4249 T heap_oop = oopDesc::load_heap_oop(p); 4250 4251 if (oopDesc::is_null(heap_oop)) { 4252 return; 4253 } 4254 4255 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 4256 4257 assert(_worker_id == _par_scan_state->queue_num(), "sanity"); 4258 4259 const InCSetState state = _g1->in_cset_state(obj); 4260 if (state.is_in_cset()) { 4261 oop forwardee; 4262 markOop m = obj->mark(); 4263 if (m->is_marked()) { 4264 forwardee = (oop) m->decode_pointer(); 4265 } else { 4266 forwardee = _par_scan_state->copy_to_survivor_space(state, obj, m); 4267 } 4268 assert(forwardee != NULL, "forwardee should not be NULL"); 4269 oopDesc::encode_store_heap_oop(p, forwardee); 4270 if (do_mark_object != G1MarkNone && forwardee != obj) { 4271 // If the object is self-forwarded we don't need to explicitly 4272 // mark it, the evacuation failure protocol will do so. 4273 mark_forwarded_object(obj, forwardee); 4274 } 4275 4276 if (barrier == G1BarrierKlass) { 4277 do_klass_barrier(p, forwardee); 4278 } 4279 } else { 4280 if (state.is_humongous()) { 4281 _g1->set_humongous_is_live(obj); 4282 } 4283 // The object is not in collection set. If we're a root scanning 4284 // closure during an initial mark pause then attempt to mark the object. 4285 if (do_mark_object == G1MarkFromRoot) { 4286 mark_object(obj); 4287 } 4288 } 4289 4290 if (barrier == G1BarrierEvac) { 4291 _par_scan_state->update_rs(_from, p, _worker_id); 4292 } 4293 } 4294 4295 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(oop* p); 4296 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(narrowOop* p); 4297 4298 class G1ParEvacuateFollowersClosure : public VoidClosure { 4299 protected: 4300 G1CollectedHeap* _g1h; 4301 G1ParScanThreadState* _par_scan_state; 4302 RefToScanQueueSet* _queues; 4303 ParallelTaskTerminator* _terminator; 4304 4305 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 4306 RefToScanQueueSet* queues() { return _queues; } 4307 ParallelTaskTerminator* terminator() { return _terminator; } 4308 4309 public: 4310 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h, 4311 G1ParScanThreadState* par_scan_state, 4312 RefToScanQueueSet* queues, 4313 ParallelTaskTerminator* terminator) 4314 : _g1h(g1h), _par_scan_state(par_scan_state), 4315 _queues(queues), _terminator(terminator) {} 4316 4317 void do_void(); 4318 4319 private: 4320 inline bool offer_termination(); 4321 }; 4322 4323 bool G1ParEvacuateFollowersClosure::offer_termination() { 4324 G1ParScanThreadState* const pss = par_scan_state(); 4325 pss->start_term_time(); 4326 const bool res = terminator()->offer_termination(); 4327 pss->end_term_time(); 4328 return res; 4329 } 4330 4331 void G1ParEvacuateFollowersClosure::do_void() { 4332 G1ParScanThreadState* const pss = par_scan_state(); 4333 pss->trim_queue(); 4334 do { 4335 pss->steal_and_trim_queue(queues()); 4336 } while (!offer_termination()); 4337 } 4338 4339 class G1KlassScanClosure : public KlassClosure { 4340 G1ParCopyHelper* _closure; 4341 bool _process_only_dirty; 4342 int _count; 4343 public: 4344 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty) 4345 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {} 4346 void do_klass(Klass* klass) { 4347 // If the klass has not been dirtied we know that there's 4348 // no references into the young gen and we can skip it. 4349 if (!_process_only_dirty || klass->has_modified_oops()) { 4350 // Clean the klass since we're going to scavenge all the metadata. 4351 klass->clear_modified_oops(); 4352 4353 // Tell the closure that this klass is the Klass to scavenge 4354 // and is the one to dirty if oops are left pointing into the young gen. 4355 _closure->set_scanned_klass(klass); 4356 4357 klass->oops_do(_closure); 4358 4359 _closure->set_scanned_klass(NULL); 4360 } 4361 _count++; 4362 } 4363 }; 4364 4365 class G1CodeBlobClosure : public CodeBlobClosure { 4366 class HeapRegionGatheringOopClosure : public OopClosure { 4367 G1CollectedHeap* _g1h; 4368 OopClosure* _work; 4369 nmethod* _nm; 4370 4371 template <typename T> 4372 void do_oop_work(T* p) { 4373 _work->do_oop(p); 4374 T oop_or_narrowoop = oopDesc::load_heap_oop(p); 4375 if (!oopDesc::is_null(oop_or_narrowoop)) { 4376 oop o = oopDesc::decode_heap_oop_not_null(oop_or_narrowoop); 4377 HeapRegion* hr = _g1h->heap_region_containing_raw(o); 4378 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"); 4379 hr->add_strong_code_root(_nm); 4380 } 4381 } 4382 4383 public: 4384 HeapRegionGatheringOopClosure(OopClosure* oc) : _g1h(G1CollectedHeap::heap()), _work(oc), _nm(NULL) {} 4385 4386 void do_oop(oop* o) { 4387 do_oop_work(o); 4388 } 4389 4390 void do_oop(narrowOop* o) { 4391 do_oop_work(o); 4392 } 4393 4394 void set_nm(nmethod* nm) { 4395 _nm = nm; 4396 } 4397 }; 4398 4399 HeapRegionGatheringOopClosure _oc; 4400 public: 4401 G1CodeBlobClosure(OopClosure* oc) : _oc(oc) {} 4402 4403 void do_code_blob(CodeBlob* cb) { 4404 nmethod* nm = cb->as_nmethod_or_null(); 4405 if (nm != NULL) { 4406 if (!nm->test_set_oops_do_mark()) { 4407 _oc.set_nm(nm); 4408 nm->oops_do(&_oc); 4409 nm->fix_oop_relocations(); 4410 } 4411 } 4412 } 4413 }; 4414 4415 class G1ParTask : public AbstractGangTask { 4416 protected: 4417 G1CollectedHeap* _g1h; 4418 RefToScanQueueSet *_queues; 4419 ParallelTaskTerminator _terminator; 4420 uint _n_workers; 4421 4422 Mutex _stats_lock; 4423 Mutex* stats_lock() { return &_stats_lock; } 4424 4425 public: 4426 G1ParTask(G1CollectedHeap* g1h, RefToScanQueueSet *task_queues) 4427 : AbstractGangTask("G1 collection"), 4428 _g1h(g1h), 4429 _queues(task_queues), 4430 _terminator(0, _queues), 4431 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true) 4432 {} 4433 4434 RefToScanQueueSet* queues() { return _queues; } 4435 4436 RefToScanQueue *work_queue(int i) { 4437 return queues()->queue(i); 4438 } 4439 4440 ParallelTaskTerminator* terminator() { return &_terminator; } 4441 4442 virtual void set_for_termination(int active_workers) { 4443 // This task calls set_n_termination() in par_non_clean_card_iterate_work() 4444 // in the young space (_par_seq_tasks) in the G1 heap 4445 // for SequentialSubTasksDone. 4446 // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap 4447 // both of which need setting by set_n_termination(). 4448 _g1h->SharedHeap::set_n_termination(active_workers); 4449 _g1h->set_n_termination(active_workers); 4450 terminator()->reset_for_reuse(active_workers); 4451 _n_workers = active_workers; 4452 } 4453 4454 // Helps out with CLD processing. 4455 // 4456 // During InitialMark we need to: 4457 // 1) Scavenge all CLDs for the young GC. 4458 // 2) Mark all objects directly reachable from strong CLDs. 4459 template <G1Mark do_mark_object> 4460 class G1CLDClosure : public CLDClosure { 4461 G1ParCopyClosure<G1BarrierNone, do_mark_object>* _oop_closure; 4462 G1ParCopyClosure<G1BarrierKlass, do_mark_object> _oop_in_klass_closure; 4463 G1KlassScanClosure _klass_in_cld_closure; 4464 bool _claim; 4465 4466 public: 4467 G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure, 4468 bool only_young, bool claim) 4469 : _oop_closure(oop_closure), 4470 _oop_in_klass_closure(oop_closure->g1(), 4471 oop_closure->pss(), 4472 oop_closure->rp()), 4473 _klass_in_cld_closure(&_oop_in_klass_closure, only_young), 4474 _claim(claim) { 4475 4476 } 4477 4478 void do_cld(ClassLoaderData* cld) { 4479 cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim); 4480 } 4481 }; 4482 4483 void work(uint worker_id) { 4484 if (worker_id >= _n_workers) return; // no work needed this round 4485 4486 double start_time_ms = os::elapsedTime() * 1000.0; 4487 _g1h->g1_policy()->phase_times()->record_gc_worker_start_time(worker_id, start_time_ms); 4488 4489 { 4490 ResourceMark rm; 4491 HandleMark hm; 4492 4493 ReferenceProcessor* rp = _g1h->ref_processor_stw(); 4494 4495 G1ParScanThreadState pss(_g1h, worker_id, rp); 4496 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp); 4497 4498 pss.set_evac_failure_closure(&evac_failure_cl); 4499 4500 bool only_young = _g1h->g1_policy()->gcs_are_young(); 4501 4502 // Non-IM young GC. 4503 G1ParCopyClosure<G1BarrierNone, G1MarkNone> scan_only_root_cl(_g1h, &pss, rp); 4504 G1CLDClosure<G1MarkNone> scan_only_cld_cl(&scan_only_root_cl, 4505 only_young, // Only process dirty klasses. 4506 false); // No need to claim CLDs. 4507 // IM young GC. 4508 // Strong roots closures. 4509 G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot> scan_mark_root_cl(_g1h, &pss, rp); 4510 G1CLDClosure<G1MarkFromRoot> scan_mark_cld_cl(&scan_mark_root_cl, 4511 false, // Process all klasses. 4512 true); // Need to claim CLDs. 4513 // Weak roots closures. 4514 G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, &pss, rp); 4515 G1CLDClosure<G1MarkPromotedFromRoot> scan_mark_weak_cld_cl(&scan_mark_weak_root_cl, 4516 false, // Process all klasses. 4517 true); // Need to claim CLDs. 4518 4519 G1CodeBlobClosure scan_only_code_cl(&scan_only_root_cl); 4520 G1CodeBlobClosure scan_mark_code_cl(&scan_mark_root_cl); 4521 // IM Weak code roots are handled later. 4522 4523 OopClosure* strong_root_cl; 4524 OopClosure* weak_root_cl; 4525 CLDClosure* strong_cld_cl; 4526 CLDClosure* weak_cld_cl; 4527 CodeBlobClosure* strong_code_cl; 4528 4529 if (_g1h->g1_policy()->during_initial_mark_pause()) { 4530 // We also need to mark copied objects. 4531 strong_root_cl = &scan_mark_root_cl; 4532 strong_cld_cl = &scan_mark_cld_cl; 4533 strong_code_cl = &scan_mark_code_cl; 4534 if (ClassUnloadingWithConcurrentMark) { 4535 weak_root_cl = &scan_mark_weak_root_cl; 4536 weak_cld_cl = &scan_mark_weak_cld_cl; 4537 } else { 4538 weak_root_cl = &scan_mark_root_cl; 4539 weak_cld_cl = &scan_mark_cld_cl; 4540 } 4541 } else { 4542 strong_root_cl = &scan_only_root_cl; 4543 weak_root_cl = &scan_only_root_cl; 4544 strong_cld_cl = &scan_only_cld_cl; 4545 weak_cld_cl = &scan_only_cld_cl; 4546 strong_code_cl = &scan_only_code_cl; 4547 } 4548 4549 4550 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss); 4551 4552 pss.start_strong_roots(); 4553 _g1h->g1_process_roots(strong_root_cl, 4554 weak_root_cl, 4555 &push_heap_rs_cl, 4556 strong_cld_cl, 4557 weak_cld_cl, 4558 strong_code_cl, 4559 worker_id); 4560 4561 pss.end_strong_roots(); 4562 4563 { 4564 double start = os::elapsedTime(); 4565 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator); 4566 evac.do_void(); 4567 double elapsed_ms = (os::elapsedTime()-start)*1000.0; 4568 double term_ms = pss.term_time()*1000.0; 4569 _g1h->g1_policy()->phase_times()->add_obj_copy_time(worker_id, elapsed_ms-term_ms); 4570 _g1h->g1_policy()->phase_times()->record_termination(worker_id, term_ms, pss.term_attempts()); 4571 } 4572 _g1h->g1_policy()->record_thread_age_table(pss.age_table()); 4573 _g1h->update_surviving_young_words(pss.surviving_young_words()+1); 4574 4575 if (PrintTerminationStats) { 4576 MutexLocker x(stats_lock()); 4577 pss.print_termination_stats(worker_id); 4578 } 4579 4580 assert(pss.queue_is_empty(), "should be empty"); 4581 4582 // Close the inner scope so that the ResourceMark and HandleMark 4583 // destructors are executed here and are included as part of the 4584 // "GC Worker Time". 4585 } 4586 4587 double end_time_ms = os::elapsedTime() * 1000.0; 4588 _g1h->g1_policy()->phase_times()->record_gc_worker_end_time(worker_id, end_time_ms); 4589 } 4590 }; 4591 4592 // *** Common G1 Evacuation Stuff 4593 4594 // This method is run in a GC worker. 4595 4596 void 4597 G1CollectedHeap:: 4598 g1_process_roots(OopClosure* scan_non_heap_roots, 4599 OopClosure* scan_non_heap_weak_roots, 4600 G1ParPushHeapRSClosure* scan_rs, 4601 CLDClosure* scan_strong_clds, 4602 CLDClosure* scan_weak_clds, 4603 CodeBlobClosure* scan_strong_code, 4604 uint worker_i) { 4605 4606 // First scan the shared roots. 4607 double ext_roots_start = os::elapsedTime(); 4608 double closure_app_time_sec = 0.0; 4609 4610 bool during_im = _g1h->g1_policy()->during_initial_mark_pause(); 4611 bool trace_metadata = during_im && ClassUnloadingWithConcurrentMark; 4612 4613 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots); 4614 BufferingOopClosure buf_scan_non_heap_weak_roots(scan_non_heap_weak_roots); 4615 4616 process_roots(false, // no scoping; this is parallel code 4617 SharedHeap::SO_None, 4618 &buf_scan_non_heap_roots, 4619 &buf_scan_non_heap_weak_roots, 4620 scan_strong_clds, 4621 // Unloading Initial Marks handle the weak CLDs separately. 4622 (trace_metadata ? NULL : scan_weak_clds), 4623 scan_strong_code); 4624 4625 // Now the CM ref_processor roots. 4626 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) { 4627 // We need to treat the discovered reference lists of the 4628 // concurrent mark ref processor as roots and keep entries 4629 // (which are added by the marking threads) on them live 4630 // until they can be processed at the end of marking. 4631 ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots); 4632 } 4633 4634 if (trace_metadata) { 4635 // Barrier to make sure all workers passed 4636 // the strong CLD and strong nmethods phases. 4637 active_strong_roots_scope()->wait_until_all_workers_done_with_threads(n_par_threads()); 4638 4639 // Now take the complement of the strong CLDs. 4640 ClassLoaderDataGraph::roots_cld_do(NULL, scan_weak_clds); 4641 } 4642 4643 // Finish up any enqueued closure apps (attributed as object copy time). 4644 buf_scan_non_heap_roots.done(); 4645 buf_scan_non_heap_weak_roots.done(); 4646 4647 double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds() 4648 + buf_scan_non_heap_weak_roots.closure_app_seconds(); 4649 4650 g1_policy()->phase_times()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0); 4651 4652 double ext_root_time_ms = 4653 ((os::elapsedTime() - ext_roots_start) - obj_copy_time_sec) * 1000.0; 4654 4655 g1_policy()->phase_times()->record_ext_root_scan_time(worker_i, ext_root_time_ms); 4656 4657 // During conc marking we have to filter the per-thread SATB buffers 4658 // to make sure we remove any oops into the CSet (which will show up 4659 // as implicitly live). 4660 double satb_filtering_ms = 0.0; 4661 if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers)) { 4662 if (mark_in_progress()) { 4663 double satb_filter_start = os::elapsedTime(); 4664 4665 JavaThread::satb_mark_queue_set().filter_thread_buffers(); 4666 4667 satb_filtering_ms = (os::elapsedTime() - satb_filter_start) * 1000.0; 4668 } 4669 } 4670 g1_policy()->phase_times()->record_satb_filtering_time(worker_i, satb_filtering_ms); 4671 4672 // Now scan the complement of the collection set. 4673 G1CodeBlobClosure scavenge_cs_nmethods(scan_non_heap_weak_roots); 4674 4675 g1_rem_set()->oops_into_collection_set_do(scan_rs, &scavenge_cs_nmethods, worker_i); 4676 4677 _process_strong_tasks->all_tasks_completed(); 4678 } 4679 4680 class G1StringSymbolTableUnlinkTask : public AbstractGangTask { 4681 private: 4682 BoolObjectClosure* _is_alive; 4683 int _initial_string_table_size; 4684 int _initial_symbol_table_size; 4685 4686 bool _process_strings; 4687 int _strings_processed; 4688 int _strings_removed; 4689 4690 bool _process_symbols; 4691 int _symbols_processed; 4692 int _symbols_removed; 4693 4694 public: 4695 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) : 4696 AbstractGangTask("String/Symbol Unlinking"), 4697 _is_alive(is_alive), 4698 _process_strings(process_strings), _strings_processed(0), _strings_removed(0), 4699 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) { 4700 4701 _initial_string_table_size = StringTable::the_table()->table_size(); 4702 _initial_symbol_table_size = SymbolTable::the_table()->table_size(); 4703 if (process_strings) { 4704 StringTable::clear_parallel_claimed_index(); 4705 } 4706 if (process_symbols) { 4707 SymbolTable::clear_parallel_claimed_index(); 4708 } 4709 } 4710 4711 ~G1StringSymbolTableUnlinkTask() { 4712 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size, 4713 err_msg("claim value %d after unlink less than initial string table size %d", 4714 StringTable::parallel_claimed_index(), _initial_string_table_size)); 4715 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size, 4716 err_msg("claim value %d after unlink less than initial symbol table size %d", 4717 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size)); 4718 4719 if (G1TraceStringSymbolTableScrubbing) { 4720 gclog_or_tty->print_cr("Cleaned string and symbol table, " 4721 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, " 4722 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed", 4723 strings_processed(), strings_removed(), 4724 symbols_processed(), symbols_removed()); 4725 } 4726 } 4727 4728 void work(uint worker_id) { 4729 int strings_processed = 0; 4730 int strings_removed = 0; 4731 int symbols_processed = 0; 4732 int symbols_removed = 0; 4733 if (_process_strings) { 4734 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed); 4735 Atomic::add(strings_processed, &_strings_processed); 4736 Atomic::add(strings_removed, &_strings_removed); 4737 } 4738 if (_process_symbols) { 4739 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed); 4740 Atomic::add(symbols_processed, &_symbols_processed); 4741 Atomic::add(symbols_removed, &_symbols_removed); 4742 } 4743 } 4744 4745 size_t strings_processed() const { return (size_t)_strings_processed; } 4746 size_t strings_removed() const { return (size_t)_strings_removed; } 4747 4748 size_t symbols_processed() const { return (size_t)_symbols_processed; } 4749 size_t symbols_removed() const { return (size_t)_symbols_removed; } 4750 }; 4751 4752 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC { 4753 private: 4754 static Monitor* _lock; 4755 4756 BoolObjectClosure* const _is_alive; 4757 const bool _unloading_occurred; 4758 const uint _num_workers; 4759 4760 // Variables used to claim nmethods. 4761 nmethod* _first_nmethod; 4762 volatile nmethod* _claimed_nmethod; 4763 4764 // The list of nmethods that need to be processed by the second pass. 4765 volatile nmethod* _postponed_list; 4766 volatile uint _num_entered_barrier; 4767 4768 public: 4769 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) : 4770 _is_alive(is_alive), 4771 _unloading_occurred(unloading_occurred), 4772 _num_workers(num_workers), 4773 _first_nmethod(NULL), 4774 _claimed_nmethod(NULL), 4775 _postponed_list(NULL), 4776 _num_entered_barrier(0) 4777 { 4778 nmethod::increase_unloading_clock(); 4779 // Get first alive nmethod 4780 NMethodIterator iter = NMethodIterator(); 4781 if(iter.next_alive()) { 4782 _first_nmethod = iter.method(); 4783 } 4784 _claimed_nmethod = (volatile nmethod*)_first_nmethod; 4785 } 4786 4787 ~G1CodeCacheUnloadingTask() { 4788 CodeCache::verify_clean_inline_caches(); 4789 4790 CodeCache::set_needs_cache_clean(false); 4791 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be"); 4792 4793 CodeCache::verify_icholder_relocations(); 4794 } 4795 4796 private: 4797 void add_to_postponed_list(nmethod* nm) { 4798 nmethod* old; 4799 do { 4800 old = (nmethod*)_postponed_list; 4801 nm->set_unloading_next(old); 4802 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old); 4803 } 4804 4805 void clean_nmethod(nmethod* nm) { 4806 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred); 4807 4808 if (postponed) { 4809 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet. 4810 add_to_postponed_list(nm); 4811 } 4812 4813 // Mark that this thread has been cleaned/unloaded. 4814 // After this call, it will be safe to ask if this nmethod was unloaded or not. 4815 nm->set_unloading_clock(nmethod::global_unloading_clock()); 4816 } 4817 4818 void clean_nmethod_postponed(nmethod* nm) { 4819 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred); 4820 } 4821 4822 static const int MaxClaimNmethods = 16; 4823 4824 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) { 4825 nmethod* first; 4826 NMethodIterator last; 4827 4828 do { 4829 *num_claimed_nmethods = 0; 4830 4831 first = (nmethod*)_claimed_nmethod; 4832 last = NMethodIterator(first); 4833 4834 if (first != NULL) { 4835 4836 for (int i = 0; i < MaxClaimNmethods; i++) { 4837 if (!last.next_alive()) { 4838 break; 4839 } 4840 claimed_nmethods[i] = last.method(); 4841 (*num_claimed_nmethods)++; 4842 } 4843 } 4844 4845 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first); 4846 } 4847 4848 nmethod* claim_postponed_nmethod() { 4849 nmethod* claim; 4850 nmethod* next; 4851 4852 do { 4853 claim = (nmethod*)_postponed_list; 4854 if (claim == NULL) { 4855 return NULL; 4856 } 4857 4858 next = claim->unloading_next(); 4859 4860 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim); 4861 4862 return claim; 4863 } 4864 4865 public: 4866 // Mark that we're done with the first pass of nmethod cleaning. 4867 void barrier_mark(uint worker_id) { 4868 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 4869 _num_entered_barrier++; 4870 if (_num_entered_barrier == _num_workers) { 4871 ml.notify_all(); 4872 } 4873 } 4874 4875 // See if we have to wait for the other workers to 4876 // finish their first-pass nmethod cleaning work. 4877 void barrier_wait(uint worker_id) { 4878 if (_num_entered_barrier < _num_workers) { 4879 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 4880 while (_num_entered_barrier < _num_workers) { 4881 ml.wait(Mutex::_no_safepoint_check_flag, 0, false); 4882 } 4883 } 4884 } 4885 4886 // Cleaning and unloading of nmethods. Some work has to be postponed 4887 // to the second pass, when we know which nmethods survive. 4888 void work_first_pass(uint worker_id) { 4889 // The first nmethods is claimed by the first worker. 4890 if (worker_id == 0 && _first_nmethod != NULL) { 4891 clean_nmethod(_first_nmethod); 4892 _first_nmethod = NULL; 4893 } 4894 4895 int num_claimed_nmethods; 4896 nmethod* claimed_nmethods[MaxClaimNmethods]; 4897 4898 while (true) { 4899 claim_nmethods(claimed_nmethods, &num_claimed_nmethods); 4900 4901 if (num_claimed_nmethods == 0) { 4902 break; 4903 } 4904 4905 for (int i = 0; i < num_claimed_nmethods; i++) { 4906 clean_nmethod(claimed_nmethods[i]); 4907 } 4908 } 4909 4910 // The nmethod cleaning helps out and does the CodeCache part of MetadataOnStackMark. 4911 // Need to retire the buffers now that this thread has stopped cleaning nmethods. 4912 MetadataOnStackMark::retire_buffer_for_thread(Thread::current()); 4913 } 4914 4915 void work_second_pass(uint worker_id) { 4916 nmethod* nm; 4917 // Take care of postponed nmethods. 4918 while ((nm = claim_postponed_nmethod()) != NULL) { 4919 clean_nmethod_postponed(nm); 4920 } 4921 } 4922 }; 4923 4924 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never); 4925 4926 class G1KlassCleaningTask : public StackObj { 4927 BoolObjectClosure* _is_alive; 4928 volatile jint _clean_klass_tree_claimed; 4929 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator; 4930 4931 public: 4932 G1KlassCleaningTask(BoolObjectClosure* is_alive) : 4933 _is_alive(is_alive), 4934 _clean_klass_tree_claimed(0), 4935 _klass_iterator() { 4936 } 4937 4938 private: 4939 bool claim_clean_klass_tree_task() { 4940 if (_clean_klass_tree_claimed) { 4941 return false; 4942 } 4943 4944 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0; 4945 } 4946 4947 InstanceKlass* claim_next_klass() { 4948 Klass* klass; 4949 do { 4950 klass =_klass_iterator.next_klass(); 4951 } while (klass != NULL && !klass->oop_is_instance()); 4952 4953 return (InstanceKlass*)klass; 4954 } 4955 4956 public: 4957 4958 void clean_klass(InstanceKlass* ik) { 4959 ik->clean_implementors_list(_is_alive); 4960 ik->clean_method_data(_is_alive); 4961 4962 // G1 specific cleanup work that has 4963 // been moved here to be done in parallel. 4964 ik->clean_dependent_nmethods(); 4965 if (JvmtiExport::has_redefined_a_class()) { 4966 InstanceKlass::purge_previous_versions(ik); 4967 } 4968 } 4969 4970 void work() { 4971 ResourceMark rm; 4972 4973 // One worker will clean the subklass/sibling klass tree. 4974 if (claim_clean_klass_tree_task()) { 4975 Klass::clean_subklass_tree(_is_alive); 4976 } 4977 4978 // All workers will help cleaning the classes, 4979 InstanceKlass* klass; 4980 while ((klass = claim_next_klass()) != NULL) { 4981 clean_klass(klass); 4982 } 4983 } 4984 }; 4985 4986 // To minimize the remark pause times, the tasks below are done in parallel. 4987 class G1ParallelCleaningTask : public AbstractGangTask { 4988 private: 4989 G1StringSymbolTableUnlinkTask _string_symbol_task; 4990 G1CodeCacheUnloadingTask _code_cache_task; 4991 G1KlassCleaningTask _klass_cleaning_task; 4992 4993 public: 4994 // The constructor is run in the VMThread. 4995 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) : 4996 AbstractGangTask("Parallel Cleaning"), 4997 _string_symbol_task(is_alive, process_strings, process_symbols), 4998 _code_cache_task(num_workers, is_alive, unloading_occurred), 4999 _klass_cleaning_task(is_alive) { 5000 } 5001 5002 void pre_work_verification() { 5003 assert(!MetadataOnStackMark::has_buffer_for_thread(Thread::current()), "Should be empty"); 5004 } 5005 5006 void post_work_verification() { 5007 assert(!MetadataOnStackMark::has_buffer_for_thread(Thread::current()), "Should be empty"); 5008 } 5009 5010 // The parallel work done by all worker threads. 5011 void work(uint worker_id) { 5012 pre_work_verification(); 5013 5014 // Do first pass of code cache cleaning. 5015 _code_cache_task.work_first_pass(worker_id); 5016 5017 // Let the threads mark that the first pass is done. 5018 _code_cache_task.barrier_mark(worker_id); 5019 5020 // Clean the Strings and Symbols. 5021 _string_symbol_task.work(worker_id); 5022 5023 // Wait for all workers to finish the first code cache cleaning pass. 5024 _code_cache_task.barrier_wait(worker_id); 5025 5026 // Do the second code cache cleaning work, which realize on 5027 // the liveness information gathered during the first pass. 5028 _code_cache_task.work_second_pass(worker_id); 5029 5030 // Clean all klasses that were not unloaded. 5031 _klass_cleaning_task.work(); 5032 5033 post_work_verification(); 5034 } 5035 }; 5036 5037 5038 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive, 5039 bool process_strings, 5040 bool process_symbols, 5041 bool class_unloading_occurred) { 5042 uint n_workers = workers()->active_workers(); 5043 5044 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, 5045 n_workers, class_unloading_occurred); 5046 set_par_threads(n_workers); 5047 workers()->run_task(&g1_unlink_task); 5048 set_par_threads(0); 5049 } 5050 5051 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive, 5052 bool process_strings, bool process_symbols) { 5053 { 5054 uint n_workers = _g1h->workers()->active_workers(); 5055 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols); 5056 set_par_threads(n_workers); 5057 workers()->run_task(&g1_unlink_task); 5058 set_par_threads(0); 5059 } 5060 5061 if (G1StringDedup::is_enabled()) { 5062 G1StringDedup::unlink(is_alive); 5063 } 5064 } 5065 5066 class G1RedirtyLoggedCardsTask : public AbstractGangTask { 5067 private: 5068 DirtyCardQueueSet* _queue; 5069 public: 5070 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { } 5071 5072 virtual void work(uint worker_id) { 5073 double start_time = os::elapsedTime(); 5074 5075 RedirtyLoggedCardTableEntryClosure cl; 5076 _queue->par_apply_closure_to_all_completed_buffers(&cl); 5077 5078 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times(); 5079 timer->record_redirty_logged_cards_time_ms(worker_id, (os::elapsedTime() - start_time) * 1000.0); 5080 timer->record_redirty_logged_cards_processed_cards(worker_id, cl.num_processed()); 5081 } 5082 }; 5083 5084 void G1CollectedHeap::redirty_logged_cards() { 5085 double redirty_logged_cards_start = os::elapsedTime(); 5086 5087 uint n_workers = _g1h->workers()->active_workers(); 5088 5089 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set()); 5090 dirty_card_queue_set().reset_for_par_iteration(); 5091 set_par_threads(n_workers); 5092 workers()->run_task(&redirty_task); 5093 set_par_threads(0); 5094 5095 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set(); 5096 dcq.merge_bufferlists(&dirty_card_queue_set()); 5097 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed"); 5098 5099 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0); 5100 } 5101 5102 // Weak Reference Processing support 5103 5104 // An always "is_alive" closure that is used to preserve referents. 5105 // If the object is non-null then it's alive. Used in the preservation 5106 // of referent objects that are pointed to by reference objects 5107 // discovered by the CM ref processor. 5108 class G1AlwaysAliveClosure: public BoolObjectClosure { 5109 G1CollectedHeap* _g1; 5110 public: 5111 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 5112 bool do_object_b(oop p) { 5113 if (p != NULL) { 5114 return true; 5115 } 5116 return false; 5117 } 5118 }; 5119 5120 bool G1STWIsAliveClosure::do_object_b(oop p) { 5121 // An object is reachable if it is outside the collection set, 5122 // or is inside and copied. 5123 return !_g1->obj_in_cs(p) || p->is_forwarded(); 5124 } 5125 5126 // Non Copying Keep Alive closure 5127 class G1KeepAliveClosure: public OopClosure { 5128 G1CollectedHeap* _g1; 5129 public: 5130 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 5131 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } 5132 void do_oop(oop* p) { 5133 oop obj = *p; 5134 assert(obj != NULL, "the caller should have filtered out NULL values"); 5135 5136 const InCSetState cset_state = _g1->in_cset_state(obj); 5137 if (!cset_state.is_in_cset_or_humongous()) { 5138 return; 5139 } 5140 if (cset_state.is_in_cset()) { 5141 assert( obj->is_forwarded(), "invariant" ); 5142 *p = obj->forwardee(); 5143 } else { 5144 assert(!obj->is_forwarded(), "invariant" ); 5145 assert(cset_state.is_humongous(), 5146 err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state.value())); 5147 _g1->set_humongous_is_live(obj); 5148 } 5149 } 5150 }; 5151 5152 // Copying Keep Alive closure - can be called from both 5153 // serial and parallel code as long as different worker 5154 // threads utilize different G1ParScanThreadState instances 5155 // and different queues. 5156 5157 class G1CopyingKeepAliveClosure: public OopClosure { 5158 G1CollectedHeap* _g1h; 5159 OopClosure* _copy_non_heap_obj_cl; 5160 G1ParScanThreadState* _par_scan_state; 5161 5162 public: 5163 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, 5164 OopClosure* non_heap_obj_cl, 5165 G1ParScanThreadState* pss): 5166 _g1h(g1h), 5167 _copy_non_heap_obj_cl(non_heap_obj_cl), 5168 _par_scan_state(pss) 5169 {} 5170 5171 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 5172 virtual void do_oop( oop* p) { do_oop_work(p); } 5173 5174 template <class T> void do_oop_work(T* p) { 5175 oop obj = oopDesc::load_decode_heap_oop(p); 5176 5177 if (_g1h->is_in_cset_or_humongous(obj)) { 5178 // If the referent object has been forwarded (either copied 5179 // to a new location or to itself in the event of an 5180 // evacuation failure) then we need to update the reference 5181 // field and, if both reference and referent are in the G1 5182 // heap, update the RSet for the referent. 5183 // 5184 // If the referent has not been forwarded then we have to keep 5185 // it alive by policy. Therefore we have copy the referent. 5186 // 5187 // If the reference field is in the G1 heap then we can push 5188 // on the PSS queue. When the queue is drained (after each 5189 // phase of reference processing) the object and it's followers 5190 // will be copied, the reference field set to point to the 5191 // new location, and the RSet updated. Otherwise we need to 5192 // use the the non-heap or metadata closures directly to copy 5193 // the referent object and update the pointer, while avoiding 5194 // updating the RSet. 5195 5196 if (_g1h->is_in_g1_reserved(p)) { 5197 _par_scan_state->push_on_queue(p); 5198 } else { 5199 assert(!Metaspace::contains((const void*)p), 5200 err_msg("Unexpectedly found a pointer from metadata: " 5201 PTR_FORMAT, p)); 5202 _copy_non_heap_obj_cl->do_oop(p); 5203 } 5204 } 5205 } 5206 }; 5207 5208 // Serial drain queue closure. Called as the 'complete_gc' 5209 // closure for each discovered list in some of the 5210 // reference processing phases. 5211 5212 class G1STWDrainQueueClosure: public VoidClosure { 5213 protected: 5214 G1CollectedHeap* _g1h; 5215 G1ParScanThreadState* _par_scan_state; 5216 5217 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 5218 5219 public: 5220 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : 5221 _g1h(g1h), 5222 _par_scan_state(pss) 5223 { } 5224 5225 void do_void() { 5226 G1ParScanThreadState* const pss = par_scan_state(); 5227 pss->trim_queue(); 5228 } 5229 }; 5230 5231 // Parallel Reference Processing closures 5232 5233 // Implementation of AbstractRefProcTaskExecutor for parallel reference 5234 // processing during G1 evacuation pauses. 5235 5236 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 5237 private: 5238 G1CollectedHeap* _g1h; 5239 RefToScanQueueSet* _queues; 5240 FlexibleWorkGang* _workers; 5241 int _active_workers; 5242 5243 public: 5244 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, 5245 FlexibleWorkGang* workers, 5246 RefToScanQueueSet *task_queues, 5247 int n_workers) : 5248 _g1h(g1h), 5249 _queues(task_queues), 5250 _workers(workers), 5251 _active_workers(n_workers) 5252 { 5253 assert(n_workers > 0, "shouldn't call this otherwise"); 5254 } 5255 5256 // Executes the given task using concurrent marking worker threads. 5257 virtual void execute(ProcessTask& task); 5258 virtual void execute(EnqueueTask& task); 5259 }; 5260 5261 // Gang task for possibly parallel reference processing 5262 5263 class G1STWRefProcTaskProxy: public AbstractGangTask { 5264 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 5265 ProcessTask& _proc_task; 5266 G1CollectedHeap* _g1h; 5267 RefToScanQueueSet *_task_queues; 5268 ParallelTaskTerminator* _terminator; 5269 5270 public: 5271 G1STWRefProcTaskProxy(ProcessTask& proc_task, 5272 G1CollectedHeap* g1h, 5273 RefToScanQueueSet *task_queues, 5274 ParallelTaskTerminator* terminator) : 5275 AbstractGangTask("Process reference objects in parallel"), 5276 _proc_task(proc_task), 5277 _g1h(g1h), 5278 _task_queues(task_queues), 5279 _terminator(terminator) 5280 {} 5281 5282 virtual void work(uint worker_id) { 5283 // The reference processing task executed by a single worker. 5284 ResourceMark rm; 5285 HandleMark hm; 5286 5287 G1STWIsAliveClosure is_alive(_g1h); 5288 5289 G1ParScanThreadState pss(_g1h, worker_id, NULL); 5290 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL); 5291 5292 pss.set_evac_failure_closure(&evac_failure_cl); 5293 5294 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL); 5295 5296 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL); 5297 5298 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5299 5300 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5301 // We also need to mark copied objects. 5302 copy_non_heap_cl = ©_mark_non_heap_cl; 5303 } 5304 5305 // Keep alive closure. 5306 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss); 5307 5308 // Complete GC closure 5309 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator); 5310 5311 // Call the reference processing task's work routine. 5312 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); 5313 5314 // Note we cannot assert that the refs array is empty here as not all 5315 // of the processing tasks (specifically phase2 - pp2_work) execute 5316 // the complete_gc closure (which ordinarily would drain the queue) so 5317 // the queue may not be empty. 5318 } 5319 }; 5320 5321 // Driver routine for parallel reference processing. 5322 // Creates an instance of the ref processing gang 5323 // task and has the worker threads execute it. 5324 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) { 5325 assert(_workers != NULL, "Need parallel worker threads."); 5326 5327 ParallelTaskTerminator terminator(_active_workers, _queues); 5328 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator); 5329 5330 _g1h->set_par_threads(_active_workers); 5331 _workers->run_task(&proc_task_proxy); 5332 _g1h->set_par_threads(0); 5333 } 5334 5335 // Gang task for parallel reference enqueueing. 5336 5337 class G1STWRefEnqueueTaskProxy: public AbstractGangTask { 5338 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; 5339 EnqueueTask& _enq_task; 5340 5341 public: 5342 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) : 5343 AbstractGangTask("Enqueue reference objects in parallel"), 5344 _enq_task(enq_task) 5345 { } 5346 5347 virtual void work(uint worker_id) { 5348 _enq_task.work(worker_id); 5349 } 5350 }; 5351 5352 // Driver routine for parallel reference enqueueing. 5353 // Creates an instance of the ref enqueueing gang 5354 // task and has the worker threads execute it. 5355 5356 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) { 5357 assert(_workers != NULL, "Need parallel worker threads."); 5358 5359 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task); 5360 5361 _g1h->set_par_threads(_active_workers); 5362 _workers->run_task(&enq_task_proxy); 5363 _g1h->set_par_threads(0); 5364 } 5365 5366 // End of weak reference support closures 5367 5368 // Abstract task used to preserve (i.e. copy) any referent objects 5369 // that are in the collection set and are pointed to by reference 5370 // objects discovered by the CM ref processor. 5371 5372 class G1ParPreserveCMReferentsTask: public AbstractGangTask { 5373 protected: 5374 G1CollectedHeap* _g1h; 5375 RefToScanQueueSet *_queues; 5376 ParallelTaskTerminator _terminator; 5377 uint _n_workers; 5378 5379 public: 5380 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) : 5381 AbstractGangTask("ParPreserveCMReferents"), 5382 _g1h(g1h), 5383 _queues(task_queues), 5384 _terminator(workers, _queues), 5385 _n_workers(workers) 5386 { } 5387 5388 void work(uint worker_id) { 5389 ResourceMark rm; 5390 HandleMark hm; 5391 5392 G1ParScanThreadState pss(_g1h, worker_id, NULL); 5393 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL); 5394 5395 pss.set_evac_failure_closure(&evac_failure_cl); 5396 5397 assert(pss.queue_is_empty(), "both queue and overflow should be empty"); 5398 5399 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL); 5400 5401 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL); 5402 5403 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5404 5405 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5406 // We also need to mark copied objects. 5407 copy_non_heap_cl = ©_mark_non_heap_cl; 5408 } 5409 5410 // Is alive closure 5411 G1AlwaysAliveClosure always_alive(_g1h); 5412 5413 // Copying keep alive closure. Applied to referent objects that need 5414 // to be copied. 5415 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss); 5416 5417 ReferenceProcessor* rp = _g1h->ref_processor_cm(); 5418 5419 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q(); 5420 uint stride = MIN2(MAX2(_n_workers, 1U), limit); 5421 5422 // limit is set using max_num_q() - which was set using ParallelGCThreads. 5423 // So this must be true - but assert just in case someone decides to 5424 // change the worker ids. 5425 assert(0 <= worker_id && worker_id < limit, "sanity"); 5426 assert(!rp->discovery_is_atomic(), "check this code"); 5427 5428 // Select discovered lists [i, i+stride, i+2*stride,...,limit) 5429 for (uint idx = worker_id; idx < limit; idx += stride) { 5430 DiscoveredList& ref_list = rp->discovered_refs()[idx]; 5431 5432 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive); 5433 while (iter.has_next()) { 5434 // Since discovery is not atomic for the CM ref processor, we 5435 // can see some null referent objects. 5436 iter.load_ptrs(DEBUG_ONLY(true)); 5437 oop ref = iter.obj(); 5438 5439 // This will filter nulls. 5440 if (iter.is_referent_alive()) { 5441 iter.make_referent_alive(); 5442 } 5443 iter.move_to_next(); 5444 } 5445 } 5446 5447 // Drain the queue - which may cause stealing 5448 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator); 5449 drain_queue.do_void(); 5450 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure 5451 assert(pss.queue_is_empty(), "should be"); 5452 } 5453 }; 5454 5455 // Weak Reference processing during an evacuation pause (part 1). 5456 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) { 5457 double ref_proc_start = os::elapsedTime(); 5458 5459 ReferenceProcessor* rp = _ref_processor_stw; 5460 assert(rp->discovery_enabled(), "should have been enabled"); 5461 5462 // Any reference objects, in the collection set, that were 'discovered' 5463 // by the CM ref processor should have already been copied (either by 5464 // applying the external root copy closure to the discovered lists, or 5465 // by following an RSet entry). 5466 // 5467 // But some of the referents, that are in the collection set, that these 5468 // reference objects point to may not have been copied: the STW ref 5469 // processor would have seen that the reference object had already 5470 // been 'discovered' and would have skipped discovering the reference, 5471 // but would not have treated the reference object as a regular oop. 5472 // As a result the copy closure would not have been applied to the 5473 // referent object. 5474 // 5475 // We need to explicitly copy these referent objects - the references 5476 // will be processed at the end of remarking. 5477 // 5478 // We also need to do this copying before we process the reference 5479 // objects discovered by the STW ref processor in case one of these 5480 // referents points to another object which is also referenced by an 5481 // object discovered by the STW ref processor. 5482 5483 assert(no_of_gc_workers == workers()->active_workers(), "Need to reset active GC workers"); 5484 5485 set_par_threads(no_of_gc_workers); 5486 G1ParPreserveCMReferentsTask keep_cm_referents(this, 5487 no_of_gc_workers, 5488 _task_queues); 5489 5490 workers()->run_task(&keep_cm_referents); 5491 5492 set_par_threads(0); 5493 5494 // Closure to test whether a referent is alive. 5495 G1STWIsAliveClosure is_alive(this); 5496 5497 // Even when parallel reference processing is enabled, the processing 5498 // of JNI refs is serial and performed serially by the current thread 5499 // rather than by a worker. The following PSS will be used for processing 5500 // JNI refs. 5501 5502 // Use only a single queue for this PSS. 5503 G1ParScanThreadState pss(this, 0, NULL); 5504 5505 // We do not embed a reference processor in the copying/scanning 5506 // closures while we're actually processing the discovered 5507 // reference objects. 5508 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL); 5509 5510 pss.set_evac_failure_closure(&evac_failure_cl); 5511 5512 assert(pss.queue_is_empty(), "pre-condition"); 5513 5514 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL); 5515 5516 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL); 5517 5518 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5519 5520 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5521 // We also need to mark copied objects. 5522 copy_non_heap_cl = ©_mark_non_heap_cl; 5523 } 5524 5525 // Keep alive closure. 5526 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, &pss); 5527 5528 // Serial Complete GC closure 5529 G1STWDrainQueueClosure drain_queue(this, &pss); 5530 5531 // Setup the soft refs policy... 5532 rp->setup_policy(false); 5533 5534 ReferenceProcessorStats stats; 5535 if (!rp->processing_is_mt()) { 5536 // Serial reference processing... 5537 stats = rp->process_discovered_references(&is_alive, 5538 &keep_alive, 5539 &drain_queue, 5540 NULL, 5541 _gc_timer_stw, 5542 _gc_tracer_stw->gc_id()); 5543 } else { 5544 // Parallel reference processing 5545 assert(rp->num_q() == no_of_gc_workers, "sanity"); 5546 assert(no_of_gc_workers <= rp->max_num_q(), "sanity"); 5547 5548 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers); 5549 stats = rp->process_discovered_references(&is_alive, 5550 &keep_alive, 5551 &drain_queue, 5552 &par_task_executor, 5553 _gc_timer_stw, 5554 _gc_tracer_stw->gc_id()); 5555 } 5556 5557 _gc_tracer_stw->report_gc_reference_stats(stats); 5558 5559 // We have completed copying any necessary live referent objects. 5560 assert(pss.queue_is_empty(), "both queue and overflow should be empty"); 5561 5562 double ref_proc_time = os::elapsedTime() - ref_proc_start; 5563 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 5564 } 5565 5566 // Weak Reference processing during an evacuation pause (part 2). 5567 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) { 5568 double ref_enq_start = os::elapsedTime(); 5569 5570 ReferenceProcessor* rp = _ref_processor_stw; 5571 assert(!rp->discovery_enabled(), "should have been disabled as part of processing"); 5572 5573 // Now enqueue any remaining on the discovered lists on to 5574 // the pending list. 5575 if (!rp->processing_is_mt()) { 5576 // Serial reference processing... 5577 rp->enqueue_discovered_references(); 5578 } else { 5579 // Parallel reference enqueueing 5580 5581 assert(no_of_gc_workers == workers()->active_workers(), 5582 "Need to reset active workers"); 5583 assert(rp->num_q() == no_of_gc_workers, "sanity"); 5584 assert(no_of_gc_workers <= rp->max_num_q(), "sanity"); 5585 5586 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers); 5587 rp->enqueue_discovered_references(&par_task_executor); 5588 } 5589 5590 rp->verify_no_references_recorded(); 5591 assert(!rp->discovery_enabled(), "should have been disabled"); 5592 5593 // FIXME 5594 // CM's reference processing also cleans up the string and symbol tables. 5595 // Should we do that here also? We could, but it is a serial operation 5596 // and could significantly increase the pause time. 5597 5598 double ref_enq_time = os::elapsedTime() - ref_enq_start; 5599 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0); 5600 } 5601 5602 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) { 5603 _expand_heap_after_alloc_failure = true; 5604 _evacuation_failed = false; 5605 5606 // Should G1EvacuationFailureALot be in effect for this GC? 5607 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) 5608 5609 g1_rem_set()->prepare_for_oops_into_collection_set_do(); 5610 5611 // Disable the hot card cache. 5612 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 5613 hot_card_cache->reset_hot_cache_claimed_index(); 5614 hot_card_cache->set_use_cache(false); 5615 5616 uint n_workers; 5617 n_workers = 5618 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 5619 workers()->active_workers(), 5620 Threads::number_of_non_daemon_threads()); 5621 assert(UseDynamicNumberOfGCThreads || 5622 n_workers == workers()->total_workers(), 5623 "If not dynamic should be using all the workers"); 5624 workers()->set_active_workers(n_workers); 5625 set_par_threads(n_workers); 5626 5627 G1ParTask g1_par_task(this, _task_queues); 5628 5629 init_for_evac_failure(NULL); 5630 5631 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty"); 5632 double start_par_time_sec = os::elapsedTime(); 5633 double end_par_time_sec; 5634 5635 { 5636 StrongRootsScope srs(this); 5637 // InitialMark needs claim bits to keep track of the marked-through CLDs. 5638 if (g1_policy()->during_initial_mark_pause()) { 5639 ClassLoaderDataGraph::clear_claimed_marks(); 5640 } 5641 5642 // The individual threads will set their evac-failure closures. 5643 if (PrintTerminationStats) G1ParScanThreadState::print_termination_stats_hdr(); 5644 // These tasks use ShareHeap::_process_strong_tasks 5645 assert(UseDynamicNumberOfGCThreads || 5646 workers()->active_workers() == workers()->total_workers(), 5647 "If not dynamic should be using all the workers"); 5648 workers()->run_task(&g1_par_task); 5649 end_par_time_sec = os::elapsedTime(); 5650 5651 // Closing the inner scope will execute the destructor 5652 // for the StrongRootsScope object. We record the current 5653 // elapsed time before closing the scope so that time 5654 // taken for the SRS destructor is NOT included in the 5655 // reported parallel time. 5656 } 5657 5658 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0; 5659 g1_policy()->phase_times()->record_par_time(par_time_ms); 5660 5661 double code_root_fixup_time_ms = 5662 (os::elapsedTime() - end_par_time_sec) * 1000.0; 5663 g1_policy()->phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms); 5664 5665 set_par_threads(0); 5666 5667 // Process any discovered reference objects - we have 5668 // to do this _before_ we retire the GC alloc regions 5669 // as we may have to copy some 'reachable' referent 5670 // objects (and their reachable sub-graphs) that were 5671 // not copied during the pause. 5672 process_discovered_references(n_workers); 5673 5674 if (G1StringDedup::is_enabled()) { 5675 G1STWIsAliveClosure is_alive(this); 5676 G1KeepAliveClosure keep_alive(this); 5677 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive); 5678 } 5679 5680 _allocator->release_gc_alloc_regions(n_workers, evacuation_info); 5681 g1_rem_set()->cleanup_after_oops_into_collection_set_do(); 5682 5683 // Reset and re-enable the hot card cache. 5684 // Note the counts for the cards in the regions in the 5685 // collection set are reset when the collection set is freed. 5686 hot_card_cache->reset_hot_cache(); 5687 hot_card_cache->set_use_cache(true); 5688 5689 purge_code_root_memory(); 5690 5691 finalize_for_evac_failure(); 5692 5693 if (evacuation_failed()) { 5694 remove_self_forwarding_pointers(); 5695 5696 // Reset the G1EvacuationFailureALot counters and flags 5697 // Note: the values are reset only when an actual 5698 // evacuation failure occurs. 5699 NOT_PRODUCT(reset_evacuation_should_fail();) 5700 } 5701 5702 // Enqueue any remaining references remaining on the STW 5703 // reference processor's discovered lists. We need to do 5704 // this after the card table is cleaned (and verified) as 5705 // the act of enqueueing entries on to the pending list 5706 // will log these updates (and dirty their associated 5707 // cards). We need these updates logged to update any 5708 // RSets. 5709 enqueue_discovered_references(n_workers); 5710 5711 redirty_logged_cards(); 5712 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 5713 } 5714 5715 void G1CollectedHeap::free_region(HeapRegion* hr, 5716 FreeRegionList* free_list, 5717 bool par, 5718 bool locked) { 5719 assert(!hr->is_free(), "the region should not be free"); 5720 assert(!hr->is_empty(), "the region should not be empty"); 5721 assert(_hrm.is_available(hr->hrm_index()), "region should be committed"); 5722 assert(free_list != NULL, "pre-condition"); 5723 5724 if (G1VerifyBitmaps) { 5725 MemRegion mr(hr->bottom(), hr->end()); 5726 concurrent_mark()->clearRangePrevBitmap(mr); 5727 } 5728 5729 // Clear the card counts for this region. 5730 // Note: we only need to do this if the region is not young 5731 // (since we don't refine cards in young regions). 5732 if (!hr->is_young()) { 5733 _cg1r->hot_card_cache()->reset_card_counts(hr); 5734 } 5735 hr->hr_clear(par, true /* clear_space */, locked /* locked */); 5736 free_list->add_ordered(hr); 5737 } 5738 5739 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 5740 FreeRegionList* free_list, 5741 bool par) { 5742 assert(hr->is_starts_humongous(), "this is only for starts humongous regions"); 5743 assert(free_list != NULL, "pre-condition"); 5744 5745 size_t hr_capacity = hr->capacity(); 5746 // We need to read this before we make the region non-humongous, 5747 // otherwise the information will be gone. 5748 uint last_index = hr->last_hc_index(); 5749 hr->clear_humongous(); 5750 free_region(hr, free_list, par); 5751 5752 uint i = hr->hrm_index() + 1; 5753 while (i < last_index) { 5754 HeapRegion* curr_hr = region_at(i); 5755 assert(curr_hr->is_continues_humongous(), "invariant"); 5756 curr_hr->clear_humongous(); 5757 free_region(curr_hr, free_list, par); 5758 i += 1; 5759 } 5760 } 5761 5762 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed, 5763 const HeapRegionSetCount& humongous_regions_removed) { 5764 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) { 5765 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 5766 _old_set.bulk_remove(old_regions_removed); 5767 _humongous_set.bulk_remove(humongous_regions_removed); 5768 } 5769 5770 } 5771 5772 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) { 5773 assert(list != NULL, "list can't be null"); 5774 if (!list->is_empty()) { 5775 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag); 5776 _hrm.insert_list_into_free_list(list); 5777 } 5778 } 5779 5780 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) { 5781 _allocator->decrease_used(bytes); 5782 } 5783 5784 class G1ParCleanupCTTask : public AbstractGangTask { 5785 G1SATBCardTableModRefBS* _ct_bs; 5786 G1CollectedHeap* _g1h; 5787 HeapRegion* volatile _su_head; 5788 public: 5789 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs, 5790 G1CollectedHeap* g1h) : 5791 AbstractGangTask("G1 Par Cleanup CT Task"), 5792 _ct_bs(ct_bs), _g1h(g1h) { } 5793 5794 void work(uint worker_id) { 5795 HeapRegion* r; 5796 while (r = _g1h->pop_dirty_cards_region()) { 5797 clear_cards(r); 5798 } 5799 } 5800 5801 void clear_cards(HeapRegion* r) { 5802 // Cards of the survivors should have already been dirtied. 5803 if (!r->is_survivor()) { 5804 _ct_bs->clear(MemRegion(r->bottom(), r->end())); 5805 } 5806 } 5807 }; 5808 5809 #ifndef PRODUCT 5810 class G1VerifyCardTableCleanup: public HeapRegionClosure { 5811 G1CollectedHeap* _g1h; 5812 G1SATBCardTableModRefBS* _ct_bs; 5813 public: 5814 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs) 5815 : _g1h(g1h), _ct_bs(ct_bs) { } 5816 virtual bool doHeapRegion(HeapRegion* r) { 5817 if (r->is_survivor()) { 5818 _g1h->verify_dirty_region(r); 5819 } else { 5820 _g1h->verify_not_dirty_region(r); 5821 } 5822 return false; 5823 } 5824 }; 5825 5826 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) { 5827 // All of the region should be clean. 5828 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5829 MemRegion mr(hr->bottom(), hr->end()); 5830 ct_bs->verify_not_dirty_region(mr); 5831 } 5832 5833 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) { 5834 // We cannot guarantee that [bottom(),end()] is dirty. Threads 5835 // dirty allocated blocks as they allocate them. The thread that 5836 // retires each region and replaces it with a new one will do a 5837 // maximal allocation to fill in [pre_dummy_top(),end()] but will 5838 // not dirty that area (one less thing to have to do while holding 5839 // a lock). So we can only verify that [bottom(),pre_dummy_top()] 5840 // is dirty. 5841 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5842 MemRegion mr(hr->bottom(), hr->pre_dummy_top()); 5843 if (hr->is_young()) { 5844 ct_bs->verify_g1_young_region(mr); 5845 } else { 5846 ct_bs->verify_dirty_region(mr); 5847 } 5848 } 5849 5850 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) { 5851 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5852 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) { 5853 verify_dirty_region(hr); 5854 } 5855 } 5856 5857 void G1CollectedHeap::verify_dirty_young_regions() { 5858 verify_dirty_young_list(_young_list->first_region()); 5859 } 5860 5861 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap, 5862 HeapWord* tams, HeapWord* end) { 5863 guarantee(tams <= end, 5864 err_msg("tams: "PTR_FORMAT" end: "PTR_FORMAT, tams, end)); 5865 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end); 5866 if (result < end) { 5867 gclog_or_tty->cr(); 5868 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: "PTR_FORMAT, 5869 bitmap_name, result); 5870 gclog_or_tty->print_cr("## %s tams: "PTR_FORMAT" end: "PTR_FORMAT, 5871 bitmap_name, tams, end); 5872 return false; 5873 } 5874 return true; 5875 } 5876 5877 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) { 5878 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap(); 5879 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap(); 5880 5881 HeapWord* bottom = hr->bottom(); 5882 HeapWord* ptams = hr->prev_top_at_mark_start(); 5883 HeapWord* ntams = hr->next_top_at_mark_start(); 5884 HeapWord* end = hr->end(); 5885 5886 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end); 5887 5888 bool res_n = true; 5889 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window 5890 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap 5891 // if we happen to be in that state. 5892 if (mark_in_progress() || !_cmThread->in_progress()) { 5893 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end); 5894 } 5895 if (!res_p || !res_n) { 5896 gclog_or_tty->print_cr("#### Bitmap verification failed for "HR_FORMAT, 5897 HR_FORMAT_PARAMS(hr)); 5898 gclog_or_tty->print_cr("#### Caller: %s", caller); 5899 return false; 5900 } 5901 return true; 5902 } 5903 5904 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) { 5905 if (!G1VerifyBitmaps) return; 5906 5907 guarantee(verify_bitmaps(caller, hr), "bitmap verification"); 5908 } 5909 5910 class G1VerifyBitmapClosure : public HeapRegionClosure { 5911 private: 5912 const char* _caller; 5913 G1CollectedHeap* _g1h; 5914 bool _failures; 5915 5916 public: 5917 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) : 5918 _caller(caller), _g1h(g1h), _failures(false) { } 5919 5920 bool failures() { return _failures; } 5921 5922 virtual bool doHeapRegion(HeapRegion* hr) { 5923 if (hr->is_continues_humongous()) return false; 5924 5925 bool result = _g1h->verify_bitmaps(_caller, hr); 5926 if (!result) { 5927 _failures = true; 5928 } 5929 return false; 5930 } 5931 }; 5932 5933 void G1CollectedHeap::check_bitmaps(const char* caller) { 5934 if (!G1VerifyBitmaps) return; 5935 5936 G1VerifyBitmapClosure cl(caller, this); 5937 heap_region_iterate(&cl); 5938 guarantee(!cl.failures(), "bitmap verification"); 5939 } 5940 5941 class G1CheckCSetFastTableClosure : public HeapRegionClosure { 5942 private: 5943 bool _failures; 5944 public: 5945 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { } 5946 5947 virtual bool doHeapRegion(HeapRegion* hr) { 5948 uint i = hr->hrm_index(); 5949 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i); 5950 if (hr->is_humongous()) { 5951 if (hr->in_collection_set()) { 5952 gclog_or_tty->print_cr("\n## humongous region %u in CSet", i); 5953 _failures = true; 5954 return true; 5955 } 5956 if (cset_state.is_in_cset()) { 5957 gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i); 5958 _failures = true; 5959 return true; 5960 } 5961 if (hr->is_continues_humongous() && cset_state.is_humongous()) { 5962 gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i); 5963 _failures = true; 5964 return true; 5965 } 5966 } else { 5967 if (cset_state.is_humongous()) { 5968 gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i); 5969 _failures = true; 5970 return true; 5971 } 5972 if (hr->in_collection_set() != cset_state.is_in_cset()) { 5973 gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u", 5974 hr->in_collection_set(), cset_state.value(), i); 5975 _failures = true; 5976 return true; 5977 } 5978 if (cset_state.is_in_cset()) { 5979 if (hr->is_young() != (cset_state.is_young())) { 5980 gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u", 5981 hr->is_young(), cset_state.value(), i); 5982 _failures = true; 5983 return true; 5984 } 5985 if (hr->is_old() != (cset_state.is_old())) { 5986 gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u", 5987 hr->is_old(), cset_state.value(), i); 5988 _failures = true; 5989 return true; 5990 } 5991 } 5992 } 5993 return false; 5994 } 5995 5996 bool failures() const { return _failures; } 5997 }; 5998 5999 bool G1CollectedHeap::check_cset_fast_test() { 6000 G1CheckCSetFastTableClosure cl; 6001 _hrm.iterate(&cl); 6002 return !cl.failures(); 6003 } 6004 #endif // PRODUCT 6005 6006 void G1CollectedHeap::cleanUpCardTable() { 6007 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 6008 double start = os::elapsedTime(); 6009 6010 { 6011 // Iterate over the dirty cards region list. 6012 G1ParCleanupCTTask cleanup_task(ct_bs, this); 6013 6014 set_par_threads(); 6015 workers()->run_task(&cleanup_task); 6016 set_par_threads(0); 6017 #ifndef PRODUCT 6018 if (G1VerifyCTCleanup || VerifyAfterGC) { 6019 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs); 6020 heap_region_iterate(&cleanup_verifier); 6021 } 6022 #endif 6023 } 6024 6025 double elapsed = os::elapsedTime() - start; 6026 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0); 6027 } 6028 6029 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) { 6030 size_t pre_used = 0; 6031 FreeRegionList local_free_list("Local List for CSet Freeing"); 6032 6033 double young_time_ms = 0.0; 6034 double non_young_time_ms = 0.0; 6035 6036 // Since the collection set is a superset of the the young list, 6037 // all we need to do to clear the young list is clear its 6038 // head and length, and unlink any young regions in the code below 6039 _young_list->clear(); 6040 6041 G1CollectorPolicy* policy = g1_policy(); 6042 6043 double start_sec = os::elapsedTime(); 6044 bool non_young = true; 6045 6046 HeapRegion* cur = cs_head; 6047 int age_bound = -1; 6048 size_t rs_lengths = 0; 6049 6050 while (cur != NULL) { 6051 assert(!is_on_master_free_list(cur), "sanity"); 6052 if (non_young) { 6053 if (cur->is_young()) { 6054 double end_sec = os::elapsedTime(); 6055 double elapsed_ms = (end_sec - start_sec) * 1000.0; 6056 non_young_time_ms += elapsed_ms; 6057 6058 start_sec = os::elapsedTime(); 6059 non_young = false; 6060 } 6061 } else { 6062 if (!cur->is_young()) { 6063 double end_sec = os::elapsedTime(); 6064 double elapsed_ms = (end_sec - start_sec) * 1000.0; 6065 young_time_ms += elapsed_ms; 6066 6067 start_sec = os::elapsedTime(); 6068 non_young = true; 6069 } 6070 } 6071 6072 rs_lengths += cur->rem_set()->occupied_locked(); 6073 6074 HeapRegion* next = cur->next_in_collection_set(); 6075 assert(cur->in_collection_set(), "bad CS"); 6076 cur->set_next_in_collection_set(NULL); 6077 cur->set_in_collection_set(false); 6078 6079 if (cur->is_young()) { 6080 int index = cur->young_index_in_cset(); 6081 assert(index != -1, "invariant"); 6082 assert((uint) index < policy->young_cset_region_length(), "invariant"); 6083 size_t words_survived = _surviving_young_words[index]; 6084 cur->record_surv_words_in_group(words_survived); 6085 6086 // At this point the we have 'popped' cur from the collection set 6087 // (linked via next_in_collection_set()) but it is still in the 6088 // young list (linked via next_young_region()). Clear the 6089 // _next_young_region field. 6090 cur->set_next_young_region(NULL); 6091 } else { 6092 int index = cur->young_index_in_cset(); 6093 assert(index == -1, "invariant"); 6094 } 6095 6096 assert( (cur->is_young() && cur->young_index_in_cset() > -1) || 6097 (!cur->is_young() && cur->young_index_in_cset() == -1), 6098 "invariant" ); 6099 6100 if (!cur->evacuation_failed()) { 6101 MemRegion used_mr = cur->used_region(); 6102 6103 // And the region is empty. 6104 assert(!used_mr.is_empty(), "Should not have empty regions in a CS."); 6105 pre_used += cur->used(); 6106 free_region(cur, &local_free_list, false /* par */, true /* locked */); 6107 } else { 6108 cur->uninstall_surv_rate_group(); 6109 if (cur->is_young()) { 6110 cur->set_young_index_in_cset(-1); 6111 } 6112 cur->set_evacuation_failed(false); 6113 // The region is now considered to be old. 6114 cur->set_old(); 6115 _old_set.add(cur); 6116 evacuation_info.increment_collectionset_used_after(cur->used()); 6117 } 6118 cur = next; 6119 } 6120 6121 evacuation_info.set_regions_freed(local_free_list.length()); 6122 policy->record_max_rs_lengths(rs_lengths); 6123 policy->cset_regions_freed(); 6124 6125 double end_sec = os::elapsedTime(); 6126 double elapsed_ms = (end_sec - start_sec) * 1000.0; 6127 6128 if (non_young) { 6129 non_young_time_ms += elapsed_ms; 6130 } else { 6131 young_time_ms += elapsed_ms; 6132 } 6133 6134 prepend_to_freelist(&local_free_list); 6135 decrement_summary_bytes(pre_used); 6136 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms); 6137 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms); 6138 } 6139 6140 class G1FreeHumongousRegionClosure : public HeapRegionClosure { 6141 private: 6142 FreeRegionList* _free_region_list; 6143 HeapRegionSet* _proxy_set; 6144 HeapRegionSetCount _humongous_regions_removed; 6145 size_t _freed_bytes; 6146 public: 6147 6148 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) : 6149 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) { 6150 } 6151 6152 virtual bool doHeapRegion(HeapRegion* r) { 6153 if (!r->is_starts_humongous()) { 6154 return false; 6155 } 6156 6157 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 6158 6159 oop obj = (oop)r->bottom(); 6160 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap(); 6161 6162 // The following checks whether the humongous object is live are sufficient. 6163 // The main additional check (in addition to having a reference from the roots 6164 // or the young gen) is whether the humongous object has a remembered set entry. 6165 // 6166 // A humongous object cannot be live if there is no remembered set for it 6167 // because: 6168 // - there can be no references from within humongous starts regions referencing 6169 // the object because we never allocate other objects into them. 6170 // (I.e. there are no intra-region references that may be missed by the 6171 // remembered set) 6172 // - as soon there is a remembered set entry to the humongous starts region 6173 // (i.e. it has "escaped" to an old object) this remembered set entry will stay 6174 // until the end of a concurrent mark. 6175 // 6176 // It is not required to check whether the object has been found dead by marking 6177 // or not, in fact it would prevent reclamation within a concurrent cycle, as 6178 // all objects allocated during that time are considered live. 6179 // SATB marking is even more conservative than the remembered set. 6180 // So if at this point in the collection there is no remembered set entry, 6181 // nobody has a reference to it. 6182 // At the start of collection we flush all refinement logs, and remembered sets 6183 // are completely up-to-date wrt to references to the humongous object. 6184 // 6185 // Other implementation considerations: 6186 // - never consider object arrays at this time because they would pose 6187 // considerable effort for cleaning up the the remembered sets. This is 6188 // required because stale remembered sets might reference locations that 6189 // are currently allocated into. 6190 uint region_idx = r->hrm_index(); 6191 if (g1h->humongous_is_live(region_idx) || 6192 g1h->humongous_region_is_always_live(region_idx)) { 6193 6194 if (G1TraceEagerReclaimHumongousObjects) { 6195 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", 6196 region_idx, 6197 obj->size()*HeapWordSize, 6198 r->bottom(), 6199 r->region_num(), 6200 r->rem_set()->occupied(), 6201 r->rem_set()->strong_code_roots_list_length(), 6202 next_bitmap->isMarked(r->bottom()), 6203 g1h->humongous_is_live(region_idx), 6204 obj->is_objArray() 6205 ); 6206 } 6207 6208 return false; 6209 } 6210 6211 guarantee(!obj->is_objArray(), 6212 err_msg("Eagerly reclaiming object arrays is not supported, but the object "PTR_FORMAT" is.", 6213 r->bottom())); 6214 6215 if (G1TraceEagerReclaimHumongousObjects) { 6216 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", 6217 region_idx, 6218 obj->size()*HeapWordSize, 6219 r->bottom(), 6220 r->region_num(), 6221 r->rem_set()->occupied(), 6222 r->rem_set()->strong_code_roots_list_length(), 6223 next_bitmap->isMarked(r->bottom()), 6224 g1h->humongous_is_live(region_idx), 6225 obj->is_objArray() 6226 ); 6227 } 6228 // Need to clear mark bit of the humongous object if already set. 6229 if (next_bitmap->isMarked(r->bottom())) { 6230 next_bitmap->clear(r->bottom()); 6231 } 6232 _freed_bytes += r->used(); 6233 r->set_containing_set(NULL); 6234 _humongous_regions_removed.increment(1u, r->capacity()); 6235 g1h->free_humongous_region(r, _free_region_list, false); 6236 6237 return false; 6238 } 6239 6240 HeapRegionSetCount& humongous_free_count() { 6241 return _humongous_regions_removed; 6242 } 6243 6244 size_t bytes_freed() const { 6245 return _freed_bytes; 6246 } 6247 6248 size_t humongous_reclaimed() const { 6249 return _humongous_regions_removed.length(); 6250 } 6251 }; 6252 6253 void G1CollectedHeap::eagerly_reclaim_humongous_regions() { 6254 assert_at_safepoint(true); 6255 6256 if (!G1EagerReclaimHumongousObjects || 6257 (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) { 6258 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0); 6259 return; 6260 } 6261 6262 double start_time = os::elapsedTime(); 6263 6264 FreeRegionList local_cleanup_list("Local Humongous Cleanup List"); 6265 6266 G1FreeHumongousRegionClosure cl(&local_cleanup_list); 6267 heap_region_iterate(&cl); 6268 6269 HeapRegionSetCount empty_set; 6270 remove_from_old_sets(empty_set, cl.humongous_free_count()); 6271 6272 G1HRPrinter* hr_printer = _g1h->hr_printer(); 6273 if (hr_printer->is_active()) { 6274 FreeRegionListIterator iter(&local_cleanup_list); 6275 while (iter.more_available()) { 6276 HeapRegion* hr = iter.get_next(); 6277 hr_printer->cleanup(hr); 6278 } 6279 } 6280 6281 prepend_to_freelist(&local_cleanup_list); 6282 decrement_summary_bytes(cl.bytes_freed()); 6283 6284 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0, 6285 cl.humongous_reclaimed()); 6286 } 6287 6288 // This routine is similar to the above but does not record 6289 // any policy statistics or update free lists; we are abandoning 6290 // the current incremental collection set in preparation of a 6291 // full collection. After the full GC we will start to build up 6292 // the incremental collection set again. 6293 // This is only called when we're doing a full collection 6294 // and is immediately followed by the tearing down of the young list. 6295 6296 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) { 6297 HeapRegion* cur = cs_head; 6298 6299 while (cur != NULL) { 6300 HeapRegion* next = cur->next_in_collection_set(); 6301 assert(cur->in_collection_set(), "bad CS"); 6302 cur->set_next_in_collection_set(NULL); 6303 cur->set_in_collection_set(false); 6304 cur->set_young_index_in_cset(-1); 6305 cur = next; 6306 } 6307 } 6308 6309 void G1CollectedHeap::set_free_regions_coming() { 6310 if (G1ConcRegionFreeingVerbose) { 6311 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " 6312 "setting free regions coming"); 6313 } 6314 6315 assert(!free_regions_coming(), "pre-condition"); 6316 _free_regions_coming = true; 6317 } 6318 6319 void G1CollectedHeap::reset_free_regions_coming() { 6320 assert(free_regions_coming(), "pre-condition"); 6321 6322 { 6323 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6324 _free_regions_coming = false; 6325 SecondaryFreeList_lock->notify_all(); 6326 } 6327 6328 if (G1ConcRegionFreeingVerbose) { 6329 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " 6330 "reset free regions coming"); 6331 } 6332 } 6333 6334 void G1CollectedHeap::wait_while_free_regions_coming() { 6335 // Most of the time we won't have to wait, so let's do a quick test 6336 // first before we take the lock. 6337 if (!free_regions_coming()) { 6338 return; 6339 } 6340 6341 if (G1ConcRegionFreeingVerbose) { 6342 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " 6343 "waiting for free regions"); 6344 } 6345 6346 { 6347 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6348 while (free_regions_coming()) { 6349 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 6350 } 6351 } 6352 6353 if (G1ConcRegionFreeingVerbose) { 6354 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " 6355 "done waiting for free regions"); 6356 } 6357 } 6358 6359 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 6360 assert(heap_lock_held_for_gc(), 6361 "the heap lock should already be held by or for this thread"); 6362 _young_list->push_region(hr); 6363 } 6364 6365 class NoYoungRegionsClosure: public HeapRegionClosure { 6366 private: 6367 bool _success; 6368 public: 6369 NoYoungRegionsClosure() : _success(true) { } 6370 bool doHeapRegion(HeapRegion* r) { 6371 if (r->is_young()) { 6372 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young", 6373 r->bottom(), r->end()); 6374 _success = false; 6375 } 6376 return false; 6377 } 6378 bool success() { return _success; } 6379 }; 6380 6381 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) { 6382 bool ret = _young_list->check_list_empty(check_sample); 6383 6384 if (check_heap) { 6385 NoYoungRegionsClosure closure; 6386 heap_region_iterate(&closure); 6387 ret = ret && closure.success(); 6388 } 6389 6390 return ret; 6391 } 6392 6393 class TearDownRegionSetsClosure : public HeapRegionClosure { 6394 private: 6395 HeapRegionSet *_old_set; 6396 6397 public: 6398 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { } 6399 6400 bool doHeapRegion(HeapRegion* r) { 6401 if (r->is_old()) { 6402 _old_set->remove(r); 6403 } else { 6404 // We ignore free regions, we'll empty the free list afterwards. 6405 // We ignore young regions, we'll empty the young list afterwards. 6406 // We ignore humongous regions, we're not tearing down the 6407 // humongous regions set. 6408 assert(r->is_free() || r->is_young() || r->is_humongous(), 6409 "it cannot be another type"); 6410 } 6411 return false; 6412 } 6413 6414 ~TearDownRegionSetsClosure() { 6415 assert(_old_set->is_empty(), "post-condition"); 6416 } 6417 }; 6418 6419 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) { 6420 assert_at_safepoint(true /* should_be_vm_thread */); 6421 6422 if (!free_list_only) { 6423 TearDownRegionSetsClosure cl(&_old_set); 6424 heap_region_iterate(&cl); 6425 6426 // Note that emptying the _young_list is postponed and instead done as 6427 // the first step when rebuilding the regions sets again. The reason for 6428 // this is that during a full GC string deduplication needs to know if 6429 // a collected region was young or old when the full GC was initiated. 6430 } 6431 _hrm.remove_all_free_regions(); 6432 } 6433 6434 class RebuildRegionSetsClosure : public HeapRegionClosure { 6435 private: 6436 bool _free_list_only; 6437 HeapRegionSet* _old_set; 6438 HeapRegionManager* _hrm; 6439 size_t _total_used; 6440 6441 public: 6442 RebuildRegionSetsClosure(bool free_list_only, 6443 HeapRegionSet* old_set, HeapRegionManager* hrm) : 6444 _free_list_only(free_list_only), 6445 _old_set(old_set), _hrm(hrm), _total_used(0) { 6446 assert(_hrm->num_free_regions() == 0, "pre-condition"); 6447 if (!free_list_only) { 6448 assert(_old_set->is_empty(), "pre-condition"); 6449 } 6450 } 6451 6452 bool doHeapRegion(HeapRegion* r) { 6453 if (r->is_continues_humongous()) { 6454 return false; 6455 } 6456 6457 if (r->is_empty()) { 6458 // Add free regions to the free list 6459 r->set_free(); 6460 r->set_allocation_context(AllocationContext::system()); 6461 _hrm->insert_into_free_list(r); 6462 } else if (!_free_list_only) { 6463 assert(!r->is_young(), "we should not come across young regions"); 6464 6465 if (r->is_humongous()) { 6466 // We ignore humongous regions, we left the humongous set unchanged 6467 } else { 6468 // Objects that were compacted would have ended up on regions 6469 // that were previously old or free. 6470 assert(r->is_free() || r->is_old(), "invariant"); 6471 // We now consider them old, so register as such. 6472 r->set_old(); 6473 _old_set->add(r); 6474 } 6475 _total_used += r->used(); 6476 } 6477 6478 return false; 6479 } 6480 6481 size_t total_used() { 6482 return _total_used; 6483 } 6484 }; 6485 6486 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { 6487 assert_at_safepoint(true /* should_be_vm_thread */); 6488 6489 if (!free_list_only) { 6490 _young_list->empty_list(); 6491 } 6492 6493 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm); 6494 heap_region_iterate(&cl); 6495 6496 if (!free_list_only) { 6497 _allocator->set_used(cl.total_used()); 6498 } 6499 assert(_allocator->used_unlocked() == recalculate_used(), 6500 err_msg("inconsistent _allocator->used_unlocked(), " 6501 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT, 6502 _allocator->used_unlocked(), recalculate_used())); 6503 } 6504 6505 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) { 6506 _refine_cte_cl->set_concurrent(concurrent); 6507 } 6508 6509 bool G1CollectedHeap::is_in_closed_subset(const void* p) const { 6510 HeapRegion* hr = heap_region_containing(p); 6511 return hr->is_in(p); 6512 } 6513 6514 // Methods for the mutator alloc region 6515 6516 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 6517 bool force) { 6518 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6519 assert(!force || g1_policy()->can_expand_young_list(), 6520 "if force is true we should be able to expand the young list"); 6521 bool young_list_full = g1_policy()->is_young_list_full(); 6522 if (force || !young_list_full) { 6523 HeapRegion* new_alloc_region = new_region(word_size, 6524 false /* is_old */, 6525 false /* do_expand */); 6526 if (new_alloc_region != NULL) { 6527 set_region_short_lived_locked(new_alloc_region); 6528 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full); 6529 check_bitmaps("Mutator Region Allocation", new_alloc_region); 6530 return new_alloc_region; 6531 } 6532 } 6533 return NULL; 6534 } 6535 6536 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 6537 size_t allocated_bytes) { 6538 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6539 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden"); 6540 6541 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region); 6542 _allocator->increase_used(allocated_bytes); 6543 _hr_printer.retire(alloc_region); 6544 // We update the eden sizes here, when the region is retired, 6545 // instead of when it's allocated, since this is the point that its 6546 // used space has been recored in _summary_bytes_used. 6547 g1mm()->update_eden_size(); 6548 } 6549 6550 void G1CollectedHeap::set_par_threads() { 6551 // Don't change the number of workers. Use the value previously set 6552 // in the workgroup. 6553 uint n_workers = workers()->active_workers(); 6554 assert(UseDynamicNumberOfGCThreads || 6555 n_workers == workers()->total_workers(), 6556 "Otherwise should be using the total number of workers"); 6557 if (n_workers == 0) { 6558 assert(false, "Should have been set in prior evacuation pause."); 6559 n_workers = ParallelGCThreads; 6560 workers()->set_active_workers(n_workers); 6561 } 6562 set_par_threads(n_workers); 6563 } 6564 6565 // Methods for the GC alloc regions 6566 6567 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, 6568 uint count, 6569 InCSetState dest) { 6570 assert(FreeList_lock->owned_by_self(), "pre-condition"); 6571 6572 if (count < g1_policy()->max_regions(dest)) { 6573 const bool is_survivor = (dest.is_young()); 6574 HeapRegion* new_alloc_region = new_region(word_size, 6575 !is_survivor, 6576 true /* do_expand */); 6577 if (new_alloc_region != NULL) { 6578 // We really only need to do this for old regions given that we 6579 // should never scan survivors. But it doesn't hurt to do it 6580 // for survivors too. 6581 new_alloc_region->record_timestamp(); 6582 if (is_survivor) { 6583 new_alloc_region->set_survivor(); 6584 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor); 6585 check_bitmaps("Survivor Region Allocation", new_alloc_region); 6586 } else { 6587 new_alloc_region->set_old(); 6588 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old); 6589 check_bitmaps("Old Region Allocation", new_alloc_region); 6590 } 6591 bool during_im = g1_policy()->during_initial_mark_pause(); 6592 new_alloc_region->note_start_of_copying(during_im); 6593 return new_alloc_region; 6594 } 6595 } 6596 return NULL; 6597 } 6598 6599 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 6600 size_t allocated_bytes, 6601 InCSetState dest) { 6602 bool during_im = g1_policy()->during_initial_mark_pause(); 6603 alloc_region->note_end_of_copying(during_im); 6604 g1_policy()->record_bytes_copied_during_gc(allocated_bytes); 6605 if (dest.is_young()) { 6606 young_list()->add_survivor_region(alloc_region); 6607 } else { 6608 _old_set.add(alloc_region); 6609 } 6610 _hr_printer.retire(alloc_region); 6611 } 6612 6613 // Heap region set verification 6614 6615 class VerifyRegionListsClosure : public HeapRegionClosure { 6616 private: 6617 HeapRegionSet* _old_set; 6618 HeapRegionSet* _humongous_set; 6619 HeapRegionManager* _hrm; 6620 6621 public: 6622 HeapRegionSetCount _old_count; 6623 HeapRegionSetCount _humongous_count; 6624 HeapRegionSetCount _free_count; 6625 6626 VerifyRegionListsClosure(HeapRegionSet* old_set, 6627 HeapRegionSet* humongous_set, 6628 HeapRegionManager* hrm) : 6629 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm), 6630 _old_count(), _humongous_count(), _free_count(){ } 6631 6632 bool doHeapRegion(HeapRegion* hr) { 6633 if (hr->is_continues_humongous()) { 6634 return false; 6635 } 6636 6637 if (hr->is_young()) { 6638 // TODO 6639 } else if (hr->is_starts_humongous()) { 6640 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrm_index())); 6641 _humongous_count.increment(1u, hr->capacity()); 6642 } else if (hr->is_empty()) { 6643 assert(_hrm->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrm_index())); 6644 _free_count.increment(1u, hr->capacity()); 6645 } else if (hr->is_old()) { 6646 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrm_index())); 6647 _old_count.increment(1u, hr->capacity()); 6648 } else { 6649 ShouldNotReachHere(); 6650 } 6651 return false; 6652 } 6653 6654 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) { 6655 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length())); 6656 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6657 old_set->total_capacity_bytes(), _old_count.capacity())); 6658 6659 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length())); 6660 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6661 humongous_set->total_capacity_bytes(), _humongous_count.capacity())); 6662 6663 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())); 6664 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6665 free_list->total_capacity_bytes(), _free_count.capacity())); 6666 } 6667 }; 6668 6669 void G1CollectedHeap::verify_region_sets() { 6670 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6671 6672 // First, check the explicit lists. 6673 _hrm.verify(); 6674 { 6675 // Given that a concurrent operation might be adding regions to 6676 // the secondary free list we have to take the lock before 6677 // verifying it. 6678 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6679 _secondary_free_list.verify_list(); 6680 } 6681 6682 // If a concurrent region freeing operation is in progress it will 6683 // be difficult to correctly attributed any free regions we come 6684 // across to the correct free list given that they might belong to 6685 // one of several (free_list, secondary_free_list, any local lists, 6686 // etc.). So, if that's the case we will skip the rest of the 6687 // verification operation. Alternatively, waiting for the concurrent 6688 // operation to complete will have a non-trivial effect on the GC's 6689 // operation (no concurrent operation will last longer than the 6690 // interval between two calls to verification) and it might hide 6691 // any issues that we would like to catch during testing. 6692 if (free_regions_coming()) { 6693 return; 6694 } 6695 6696 // Make sure we append the secondary_free_list on the free_list so 6697 // that all free regions we will come across can be safely 6698 // attributed to the free_list. 6699 append_secondary_free_list_if_not_empty_with_lock(); 6700 6701 // Finally, make sure that the region accounting in the lists is 6702 // consistent with what we see in the heap. 6703 6704 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm); 6705 heap_region_iterate(&cl); 6706 cl.verify_counts(&_old_set, &_humongous_set, &_hrm); 6707 } 6708 6709 // Optimized nmethod scanning 6710 6711 class RegisterNMethodOopClosure: public OopClosure { 6712 G1CollectedHeap* _g1h; 6713 nmethod* _nm; 6714 6715 template <class T> void do_oop_work(T* p) { 6716 T heap_oop = oopDesc::load_heap_oop(p); 6717 if (!oopDesc::is_null(heap_oop)) { 6718 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 6719 HeapRegion* hr = _g1h->heap_region_containing(obj); 6720 assert(!hr->is_continues_humongous(), 6721 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT 6722 " starting at "HR_FORMAT, 6723 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()))); 6724 6725 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries. 6726 hr->add_strong_code_root_locked(_nm); 6727 } 6728 } 6729 6730 public: 6731 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 6732 _g1h(g1h), _nm(nm) {} 6733 6734 void do_oop(oop* p) { do_oop_work(p); } 6735 void do_oop(narrowOop* p) { do_oop_work(p); } 6736 }; 6737 6738 class UnregisterNMethodOopClosure: public OopClosure { 6739 G1CollectedHeap* _g1h; 6740 nmethod* _nm; 6741 6742 template <class T> void do_oop_work(T* p) { 6743 T heap_oop = oopDesc::load_heap_oop(p); 6744 if (!oopDesc::is_null(heap_oop)) { 6745 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 6746 HeapRegion* hr = _g1h->heap_region_containing(obj); 6747 assert(!hr->is_continues_humongous(), 6748 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT 6749 " starting at "HR_FORMAT, 6750 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()))); 6751 6752 hr->remove_strong_code_root(_nm); 6753 } 6754 } 6755 6756 public: 6757 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 6758 _g1h(g1h), _nm(nm) {} 6759 6760 void do_oop(oop* p) { do_oop_work(p); } 6761 void do_oop(narrowOop* p) { do_oop_work(p); } 6762 }; 6763 6764 void G1CollectedHeap::register_nmethod(nmethod* nm) { 6765 CollectedHeap::register_nmethod(nm); 6766 6767 guarantee(nm != NULL, "sanity"); 6768 RegisterNMethodOopClosure reg_cl(this, nm); 6769 nm->oops_do(®_cl); 6770 } 6771 6772 void G1CollectedHeap::unregister_nmethod(nmethod* nm) { 6773 CollectedHeap::unregister_nmethod(nm); 6774 6775 guarantee(nm != NULL, "sanity"); 6776 UnregisterNMethodOopClosure reg_cl(this, nm); 6777 nm->oops_do(®_cl, true); 6778 } 6779 6780 void G1CollectedHeap::purge_code_root_memory() { 6781 double purge_start = os::elapsedTime(); 6782 G1CodeRootSet::purge(); 6783 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0; 6784 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms); 6785 } 6786 6787 class RebuildStrongCodeRootClosure: public CodeBlobClosure { 6788 G1CollectedHeap* _g1h; 6789 6790 public: 6791 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) : 6792 _g1h(g1h) {} 6793 6794 void do_code_blob(CodeBlob* cb) { 6795 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL; 6796 if (nm == NULL) { 6797 return; 6798 } 6799 6800 if (ScavengeRootsInCode) { 6801 _g1h->register_nmethod(nm); 6802 } 6803 } 6804 }; 6805 6806 void G1CollectedHeap::rebuild_strong_code_roots() { 6807 RebuildStrongCodeRootClosure blob_cl(this); 6808 CodeCache::blobs_do(&blob_cl); 6809 }