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 #define ATTRIBUTE_PRINTF(x,y) // FIXME, formats are a mess. 27 #endif 28 29 #include "precompiled.hpp" 30 #include "classfile/metadataOnStackMark.hpp" 31 #include "code/codeCache.hpp" 32 #include "code/icBuffer.hpp" 33 #include "gc_implementation/g1/bufferingOopClosure.hpp" 34 #include "gc_implementation/g1/concurrentG1Refine.hpp" 35 #include "gc_implementation/g1/concurrentG1RefineThread.hpp" 36 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp" 37 #include "gc_implementation/g1/g1AllocRegion.inline.hpp" 38 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp" 39 #include "gc_implementation/g1/g1CollectorPolicy.hpp" 40 #include "gc_implementation/g1/g1ErgoVerbose.hpp" 41 #include "gc_implementation/g1/g1EvacFailure.hpp" 42 #include "gc_implementation/g1/g1GCPhaseTimes.hpp" 43 #include "gc_implementation/g1/g1Log.hpp" 44 #include "gc_implementation/g1/g1MarkSweep.hpp" 45 #include "gc_implementation/g1/g1OopClosures.inline.hpp" 46 #include "gc_implementation/g1/g1ParScanThreadState.inline.hpp" 47 #include "gc_implementation/g1/g1RegionToSpaceMapper.hpp" 48 #include "gc_implementation/g1/g1RemSet.inline.hpp" 49 #include "gc_implementation/g1/g1StringDedup.hpp" 50 #include "gc_implementation/g1/g1YCTypes.hpp" 51 #include "gc_implementation/g1/heapRegion.inline.hpp" 52 #include "gc_implementation/g1/heapRegionRemSet.hpp" 53 #include "gc_implementation/g1/heapRegionSet.inline.hpp" 54 #include "gc_implementation/g1/vm_operations_g1.hpp" 55 #include "gc_implementation/shared/gcHeapSummary.hpp" 56 #include "gc_implementation/shared/gcTimer.hpp" 57 #include "gc_implementation/shared/gcTrace.hpp" 58 #include "gc_implementation/shared/gcTraceTime.hpp" 59 #include "gc_implementation/shared/isGCActiveMark.hpp" 60 #include "memory/allocation.hpp" 61 #include "memory/gcLocker.inline.hpp" 62 #include "memory/generationSpec.hpp" 63 #include "memory/iterator.hpp" 64 #include "memory/referenceProcessor.hpp" 65 #include "oops/oop.inline.hpp" 66 #include "oops/oop.pcgc.inline.hpp" 67 #include "runtime/orderAccess.inline.hpp" 68 #include "runtime/vmThread.hpp" 69 70 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0; 71 72 // turn it on so that the contents of the young list (scan-only / 73 // to-be-collected) are printed at "strategic" points before / during 74 // / after the collection --- this is useful for debugging 75 #define YOUNG_LIST_VERBOSE 0 76 // CURRENT STATUS 77 // This file is under construction. Search for "FIXME". 78 79 // INVARIANTS/NOTES 80 // 81 // All allocation activity covered by the G1CollectedHeap interface is 82 // serialized by acquiring the HeapLock. This happens in mem_allocate 83 // and allocate_new_tlab, which are the "entry" points to the 84 // allocation code from the rest of the JVM. (Note that this does not 85 // apply to TLAB allocation, which is not part of this interface: it 86 // is done by clients of this interface.) 87 88 // Notes on implementation of parallelism in different tasks. 89 // 90 // G1ParVerifyTask uses heap_region_par_iterate_chunked() for parallelism. 91 // The number of GC workers is passed to heap_region_par_iterate_chunked(). 92 // It does use run_task() which sets _n_workers in the task. 93 // G1ParTask executes g1_process_roots() -> 94 // SharedHeap::process_roots() which calls eventually to 95 // CardTableModRefBS::par_non_clean_card_iterate_work() which uses 96 // SequentialSubTasksDone. SharedHeap::process_roots() also 97 // directly uses SubTasksDone (_process_strong_tasks field in SharedHeap). 98 // 99 100 // Local to this file. 101 102 class RefineCardTableEntryClosure: public CardTableEntryClosure { 103 bool _concurrent; 104 public: 105 RefineCardTableEntryClosure() : _concurrent(true) { } 106 107 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 108 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false); 109 // This path is executed by the concurrent refine or mutator threads, 110 // concurrently, and so we do not care if card_ptr contains references 111 // that point into the collection set. 112 assert(!oops_into_cset, "should be"); 113 114 if (_concurrent && SuspendibleThreadSet::should_yield()) { 115 // Caller will actually yield. 116 return false; 117 } 118 // Otherwise, we finished successfully; return true. 119 return true; 120 } 121 122 void set_concurrent(bool b) { _concurrent = b; } 123 }; 124 125 126 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure { 127 size_t _num_processed; 128 CardTableModRefBS* _ctbs; 129 int _histo[256]; 130 131 public: 132 ClearLoggedCardTableEntryClosure() : 133 _num_processed(0), _ctbs(G1CollectedHeap::heap()->g1_barrier_set()) 134 { 135 for (int i = 0; i < 256; i++) _histo[i] = 0; 136 } 137 138 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 139 unsigned char* ujb = (unsigned char*)card_ptr; 140 int ind = (int)(*ujb); 141 _histo[ind]++; 142 143 *card_ptr = (jbyte)CardTableModRefBS::clean_card_val(); 144 _num_processed++; 145 146 return true; 147 } 148 149 size_t num_processed() { return _num_processed; } 150 151 void print_histo() { 152 gclog_or_tty->print_cr("Card table value histogram:"); 153 for (int i = 0; i < 256; i++) { 154 if (_histo[i] != 0) { 155 gclog_or_tty->print_cr(" %d: %d", i, _histo[i]); 156 } 157 } 158 } 159 }; 160 161 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure { 162 private: 163 size_t _num_processed; 164 165 public: 166 RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { } 167 168 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 169 *card_ptr = CardTableModRefBS::dirty_card_val(); 170 _num_processed++; 171 return true; 172 } 173 174 size_t num_processed() const { return _num_processed; } 175 }; 176 177 YoungList::YoungList(G1CollectedHeap* g1h) : 178 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0), 179 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) { 180 guarantee(check_list_empty(false), "just making sure..."); 181 } 182 183 void YoungList::push_region(HeapRegion *hr) { 184 assert(!hr->is_young(), "should not already be young"); 185 assert(hr->get_next_young_region() == NULL, "cause it should!"); 186 187 hr->set_next_young_region(_head); 188 _head = hr; 189 190 _g1h->g1_policy()->set_region_eden(hr, (int) _length); 191 ++_length; 192 } 193 194 void YoungList::add_survivor_region(HeapRegion* hr) { 195 assert(hr->is_survivor(), "should be flagged as survivor region"); 196 assert(hr->get_next_young_region() == NULL, "cause it should!"); 197 198 hr->set_next_young_region(_survivor_head); 199 if (_survivor_head == NULL) { 200 _survivor_tail = hr; 201 } 202 _survivor_head = hr; 203 ++_survivor_length; 204 } 205 206 void YoungList::empty_list(HeapRegion* list) { 207 while (list != NULL) { 208 HeapRegion* next = list->get_next_young_region(); 209 list->set_next_young_region(NULL); 210 list->uninstall_surv_rate_group(); 211 // This is called before a Full GC and all the non-empty / 212 // non-humongous regions at the end of the Full GC will end up as 213 // old anyway. 214 list->set_old(); 215 list = next; 216 } 217 } 218 219 void YoungList::empty_list() { 220 assert(check_list_well_formed(), "young list should be well formed"); 221 222 empty_list(_head); 223 _head = NULL; 224 _length = 0; 225 226 empty_list(_survivor_head); 227 _survivor_head = NULL; 228 _survivor_tail = NULL; 229 _survivor_length = 0; 230 231 _last_sampled_rs_lengths = 0; 232 233 assert(check_list_empty(false), "just making sure..."); 234 } 235 236 bool YoungList::check_list_well_formed() { 237 bool ret = true; 238 239 uint length = 0; 240 HeapRegion* curr = _head; 241 HeapRegion* last = NULL; 242 while (curr != NULL) { 243 if (!curr->is_young()) { 244 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" " 245 "incorrectly tagged (y: %d, surv: %d)", 246 curr->bottom(), curr->end(), 247 curr->is_young(), curr->is_survivor()); 248 ret = false; 249 } 250 ++length; 251 last = curr; 252 curr = curr->get_next_young_region(); 253 } 254 ret = ret && (length == _length); 255 256 if (!ret) { 257 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!"); 258 gclog_or_tty->print_cr("### list has %u entries, _length is %u", 259 length, _length); 260 } 261 262 return ret; 263 } 264 265 bool YoungList::check_list_empty(bool check_sample) { 266 bool ret = true; 267 268 if (_length != 0) { 269 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u", 270 _length); 271 ret = false; 272 } 273 if (check_sample && _last_sampled_rs_lengths != 0) { 274 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths"); 275 ret = false; 276 } 277 if (_head != NULL) { 278 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head"); 279 ret = false; 280 } 281 if (!ret) { 282 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty"); 283 } 284 285 return ret; 286 } 287 288 void 289 YoungList::rs_length_sampling_init() { 290 _sampled_rs_lengths = 0; 291 _curr = _head; 292 } 293 294 bool 295 YoungList::rs_length_sampling_more() { 296 return _curr != NULL; 297 } 298 299 void 300 YoungList::rs_length_sampling_next() { 301 assert( _curr != NULL, "invariant" ); 302 size_t rs_length = _curr->rem_set()->occupied(); 303 304 _sampled_rs_lengths += rs_length; 305 306 // The current region may not yet have been added to the 307 // incremental collection set (it gets added when it is 308 // retired as the current allocation region). 309 if (_curr->in_collection_set()) { 310 // Update the collection set policy information for this region 311 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length); 312 } 313 314 _curr = _curr->get_next_young_region(); 315 if (_curr == NULL) { 316 _last_sampled_rs_lengths = _sampled_rs_lengths; 317 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths); 318 } 319 } 320 321 void 322 YoungList::reset_auxilary_lists() { 323 guarantee( is_empty(), "young list should be empty" ); 324 assert(check_list_well_formed(), "young list should be well formed"); 325 326 // Add survivor regions to SurvRateGroup. 327 _g1h->g1_policy()->note_start_adding_survivor_regions(); 328 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */); 329 330 int young_index_in_cset = 0; 331 for (HeapRegion* curr = _survivor_head; 332 curr != NULL; 333 curr = curr->get_next_young_region()) { 334 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset); 335 336 // The region is a non-empty survivor so let's add it to 337 // the incremental collection set for the next evacuation 338 // pause. 339 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr); 340 young_index_in_cset += 1; 341 } 342 assert((uint) young_index_in_cset == _survivor_length, "post-condition"); 343 _g1h->g1_policy()->note_stop_adding_survivor_regions(); 344 345 _head = _survivor_head; 346 _length = _survivor_length; 347 if (_survivor_head != NULL) { 348 assert(_survivor_tail != NULL, "cause it shouldn't be"); 349 assert(_survivor_length > 0, "invariant"); 350 _survivor_tail->set_next_young_region(NULL); 351 } 352 353 // Don't clear the survivor list handles until the start of 354 // the next evacuation pause - we need it in order to re-tag 355 // the survivor regions from this evacuation pause as 'young' 356 // at the start of the next. 357 358 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */); 359 360 assert(check_list_well_formed(), "young list should be well formed"); 361 } 362 363 void YoungList::print() { 364 HeapRegion* lists[] = {_head, _survivor_head}; 365 const char* names[] = {"YOUNG", "SURVIVOR"}; 366 367 for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) { 368 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]); 369 HeapRegion *curr = lists[list]; 370 if (curr == NULL) 371 gclog_or_tty->print_cr(" empty"); 372 while (curr != NULL) { 373 gclog_or_tty->print_cr(" "HR_FORMAT", P: "PTR_FORMAT ", N: "PTR_FORMAT", age: %4d", 374 HR_FORMAT_PARAMS(curr), 375 curr->prev_top_at_mark_start(), 376 curr->next_top_at_mark_start(), 377 curr->age_in_surv_rate_group_cond()); 378 curr = curr->get_next_young_region(); 379 } 380 } 381 382 gclog_or_tty->cr(); 383 } 384 385 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) { 386 OtherRegionsTable::invalidate(start_idx, num_regions); 387 } 388 389 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) { 390 // The from card cache is not the memory that is actually committed. So we cannot 391 // take advantage of the zero_filled parameter. 392 reset_from_card_cache(start_idx, num_regions); 393 } 394 395 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr) 396 { 397 // Claim the right to put the region on the dirty cards region list 398 // by installing a self pointer. 399 HeapRegion* next = hr->get_next_dirty_cards_region(); 400 if (next == NULL) { 401 HeapRegion* res = (HeapRegion*) 402 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(), 403 NULL); 404 if (res == NULL) { 405 HeapRegion* head; 406 do { 407 // Put the region to the dirty cards region list. 408 head = _dirty_cards_region_list; 409 next = (HeapRegion*) 410 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head); 411 if (next == head) { 412 assert(hr->get_next_dirty_cards_region() == hr, 413 "hr->get_next_dirty_cards_region() != hr"); 414 if (next == NULL) { 415 // The last region in the list points to itself. 416 hr->set_next_dirty_cards_region(hr); 417 } else { 418 hr->set_next_dirty_cards_region(next); 419 } 420 } 421 } while (next != head); 422 } 423 } 424 } 425 426 HeapRegion* G1CollectedHeap::pop_dirty_cards_region() 427 { 428 HeapRegion* head; 429 HeapRegion* hr; 430 do { 431 head = _dirty_cards_region_list; 432 if (head == NULL) { 433 return NULL; 434 } 435 HeapRegion* new_head = head->get_next_dirty_cards_region(); 436 if (head == new_head) { 437 // The last region. 438 new_head = NULL; 439 } 440 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list, 441 head); 442 } while (hr != head); 443 assert(hr != NULL, "invariant"); 444 hr->set_next_dirty_cards_region(NULL); 445 return hr; 446 } 447 448 #ifdef ASSERT 449 // A region is added to the collection set as it is retired 450 // so an address p can point to a region which will be in the 451 // collection set but has not yet been retired. This method 452 // therefore is only accurate during a GC pause after all 453 // regions have been retired. It is used for debugging 454 // to check if an nmethod has references to objects that can 455 // be move during a partial collection. Though it can be 456 // inaccurate, it is sufficient for G1 because the conservative 457 // implementation of is_scavengable() for G1 will indicate that 458 // all nmethods must be scanned during a partial collection. 459 bool G1CollectedHeap::is_in_partial_collection(const void* p) { 460 if (p == NULL) { 461 return false; 462 } 463 return heap_region_containing(p)->in_collection_set(); 464 } 465 #endif 466 467 // Returns true if the reference points to an object that 468 // can move in an incremental collection. 469 bool G1CollectedHeap::is_scavengable(const void* p) { 470 HeapRegion* hr = heap_region_containing(p); 471 return !hr->isHumongous(); 472 } 473 474 void G1CollectedHeap::check_ct_logs_at_safepoint() { 475 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 476 CardTableModRefBS* ct_bs = g1_barrier_set(); 477 478 // Count the dirty cards at the start. 479 CountNonCleanMemRegionClosure count1(this); 480 ct_bs->mod_card_iterate(&count1); 481 int orig_count = count1.n(); 482 483 // First clear the logged cards. 484 ClearLoggedCardTableEntryClosure clear; 485 dcqs.apply_closure_to_all_completed_buffers(&clear); 486 dcqs.iterate_closure_all_threads(&clear, false); 487 clear.print_histo(); 488 489 // Now ensure that there's no dirty cards. 490 CountNonCleanMemRegionClosure count2(this); 491 ct_bs->mod_card_iterate(&count2); 492 if (count2.n() != 0) { 493 gclog_or_tty->print_cr("Card table has %d entries; %d originally", 494 count2.n(), orig_count); 495 } 496 guarantee(count2.n() == 0, "Card table should be clean."); 497 498 RedirtyLoggedCardTableEntryClosure redirty; 499 dcqs.apply_closure_to_all_completed_buffers(&redirty); 500 dcqs.iterate_closure_all_threads(&redirty, false); 501 gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.", 502 clear.num_processed(), orig_count); 503 guarantee(redirty.num_processed() == clear.num_processed(), 504 err_msg("Redirtied "SIZE_FORMAT" cards, bug cleared "SIZE_FORMAT, 505 redirty.num_processed(), clear.num_processed())); 506 507 CountNonCleanMemRegionClosure count3(this); 508 ct_bs->mod_card_iterate(&count3); 509 if (count3.n() != orig_count) { 510 gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.", 511 orig_count, count3.n()); 512 guarantee(count3.n() >= orig_count, "Should have restored them all."); 513 } 514 } 515 516 // Private class members. 517 518 G1CollectedHeap* G1CollectedHeap::_g1h; 519 520 // Private methods. 521 522 HeapRegion* 523 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) { 524 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 525 while (!_secondary_free_list.is_empty() || free_regions_coming()) { 526 if (!_secondary_free_list.is_empty()) { 527 if (G1ConcRegionFreeingVerbose) { 528 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 529 "secondary_free_list has %u entries", 530 _secondary_free_list.length()); 531 } 532 // It looks as if there are free regions available on the 533 // secondary_free_list. Let's move them to the free_list and try 534 // again to allocate from it. 535 append_secondary_free_list(); 536 537 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not " 538 "empty we should have moved at least one entry to the free_list"); 539 HeapRegion* res = _hrm.allocate_free_region(is_old); 540 if (G1ConcRegionFreeingVerbose) { 541 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 542 "allocated "HR_FORMAT" from secondary_free_list", 543 HR_FORMAT_PARAMS(res)); 544 } 545 return res; 546 } 547 548 // Wait here until we get notified either when (a) there are no 549 // more free regions coming or (b) some regions have been moved on 550 // the secondary_free_list. 551 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 552 } 553 554 if (G1ConcRegionFreeingVerbose) { 555 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 556 "could not allocate from secondary_free_list"); 557 } 558 return NULL; 559 } 560 561 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) { 562 assert(!isHumongous(word_size) || word_size <= HeapRegion::GrainWords, 563 "the only time we use this to allocate a humongous region is " 564 "when we are allocating a single humongous region"); 565 566 HeapRegion* res; 567 if (G1StressConcRegionFreeing) { 568 if (!_secondary_free_list.is_empty()) { 569 if (G1ConcRegionFreeingVerbose) { 570 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 571 "forced to look at the secondary_free_list"); 572 } 573 res = new_region_try_secondary_free_list(is_old); 574 if (res != NULL) { 575 return res; 576 } 577 } 578 } 579 580 res = _hrm.allocate_free_region(is_old); 581 582 if (res == NULL) { 583 if (G1ConcRegionFreeingVerbose) { 584 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 585 "res == NULL, trying the secondary_free_list"); 586 } 587 res = new_region_try_secondary_free_list(is_old); 588 } 589 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) { 590 // Currently, only attempts to allocate GC alloc regions set 591 // do_expand to true. So, we should only reach here during a 592 // safepoint. If this assumption changes we might have to 593 // reconsider the use of _expand_heap_after_alloc_failure. 594 assert(SafepointSynchronize::is_at_safepoint(), "invariant"); 595 596 ergo_verbose1(ErgoHeapSizing, 597 "attempt heap expansion", 598 ergo_format_reason("region allocation request failed") 599 ergo_format_byte("allocation request"), 600 word_size * HeapWordSize); 601 if (expand(word_size * HeapWordSize)) { 602 // Given that expand() succeeded in expanding the heap, and we 603 // always expand the heap by an amount aligned to the heap 604 // region size, the free list should in theory not be empty. 605 // In either case allocate_free_region() will check for NULL. 606 res = _hrm.allocate_free_region(is_old); 607 } else { 608 _expand_heap_after_alloc_failure = false; 609 } 610 } 611 return res; 612 } 613 614 HeapWord* 615 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first, 616 uint num_regions, 617 size_t word_size, 618 AllocationContext_t context) { 619 assert(first != G1_NO_HRM_INDEX, "pre-condition"); 620 assert(isHumongous(word_size), "word_size should be humongous"); 621 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition"); 622 623 // Index of last region in the series + 1. 624 uint last = first + num_regions; 625 626 // We need to initialize the region(s) we just discovered. This is 627 // a bit tricky given that it can happen concurrently with 628 // refinement threads refining cards on these regions and 629 // potentially wanting to refine the BOT as they are scanning 630 // those cards (this can happen shortly after a cleanup; see CR 631 // 6991377). So we have to set up the region(s) carefully and in 632 // a specific order. 633 634 // The word size sum of all the regions we will allocate. 635 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords; 636 assert(word_size <= word_size_sum, "sanity"); 637 638 // This will be the "starts humongous" region. 639 HeapRegion* first_hr = region_at(first); 640 // The header of the new object will be placed at the bottom of 641 // the first region. 642 HeapWord* new_obj = first_hr->bottom(); 643 // This will be the new end of the first region in the series that 644 // should also match the end of the last region in the series. 645 HeapWord* new_end = new_obj + word_size_sum; 646 // This will be the new top of the first region that will reflect 647 // this allocation. 648 HeapWord* new_top = new_obj + word_size; 649 650 // First, we need to zero the header of the space that we will be 651 // allocating. When we update top further down, some refinement 652 // threads might try to scan the region. By zeroing the header we 653 // ensure that any thread that will try to scan the region will 654 // come across the zero klass word and bail out. 655 // 656 // NOTE: It would not have been correct to have used 657 // CollectedHeap::fill_with_object() and make the space look like 658 // an int array. The thread that is doing the allocation will 659 // later update the object header to a potentially different array 660 // type and, for a very short period of time, the klass and length 661 // fields will be inconsistent. This could cause a refinement 662 // thread to calculate the object size incorrectly. 663 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0); 664 665 // We will set up the first region as "starts humongous". This 666 // will also update the BOT covering all the regions to reflect 667 // that there is a single object that starts at the bottom of the 668 // first region. 669 first_hr->set_startsHumongous(new_top, new_end); 670 first_hr->set_allocation_context(context); 671 // Then, if there are any, we will set up the "continues 672 // humongous" regions. 673 HeapRegion* hr = NULL; 674 for (uint i = first + 1; i < last; ++i) { 675 hr = region_at(i); 676 hr->set_continuesHumongous(first_hr); 677 hr->set_allocation_context(context); 678 } 679 // If we have "continues humongous" regions (hr != NULL), then the 680 // end of the last one should match new_end. 681 assert(hr == NULL || hr->end() == new_end, "sanity"); 682 683 // Up to this point no concurrent thread would have been able to 684 // do any scanning on any region in this series. All the top 685 // fields still point to bottom, so the intersection between 686 // [bottom,top] and [card_start,card_end] will be empty. Before we 687 // update the top fields, we'll do a storestore to make sure that 688 // no thread sees the update to top before the zeroing of the 689 // object header and the BOT initialization. 690 OrderAccess::storestore(); 691 692 // Now that the BOT and the object header have been initialized, 693 // we can update top of the "starts humongous" region. 694 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(), 695 "new_top should be in this region"); 696 first_hr->set_top(new_top); 697 if (_hr_printer.is_active()) { 698 HeapWord* bottom = first_hr->bottom(); 699 HeapWord* end = first_hr->orig_end(); 700 if ((first + 1) == last) { 701 // the series has a single humongous region 702 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top); 703 } else { 704 // the series has more than one humongous regions 705 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end); 706 } 707 } 708 709 // Now, we will update the top fields of the "continues humongous" 710 // regions. The reason we need to do this is that, otherwise, 711 // these regions would look empty and this will confuse parts of 712 // G1. For example, the code that looks for a consecutive number 713 // of empty regions will consider them empty and try to 714 // re-allocate them. We can extend is_empty() to also include 715 // !continuesHumongous(), but it is easier to just update the top 716 // fields here. The way we set top for all regions (i.e., top == 717 // end for all regions but the last one, top == new_top for the 718 // last one) is actually used when we will free up the humongous 719 // region in free_humongous_region(). 720 hr = NULL; 721 for (uint i = first + 1; i < last; ++i) { 722 hr = region_at(i); 723 if ((i + 1) == last) { 724 // last continues humongous region 725 assert(hr->bottom() < new_top && new_top <= hr->end(), 726 "new_top should fall on this region"); 727 hr->set_top(new_top); 728 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top); 729 } else { 730 // not last one 731 assert(new_top > hr->end(), "new_top should be above this region"); 732 hr->set_top(hr->end()); 733 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end()); 734 } 735 } 736 // If we have continues humongous regions (hr != NULL), then the 737 // end of the last one should match new_end and its top should 738 // match new_top. 739 assert(hr == NULL || 740 (hr->end() == new_end && hr->top() == new_top), "sanity"); 741 check_bitmaps("Humongous Region Allocation", first_hr); 742 743 assert(first_hr->used() == word_size * HeapWordSize, "invariant"); 744 _allocator->increase_used(first_hr->used()); 745 _humongous_set.add(first_hr); 746 747 return new_obj; 748 } 749 750 // If could fit into free regions w/o expansion, try. 751 // Otherwise, if can expand, do so. 752 // Otherwise, if using ex regions might help, try with ex given back. 753 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) { 754 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 755 756 verify_region_sets_optional(); 757 758 uint first = G1_NO_HRM_INDEX; 759 uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords); 760 761 if (obj_regions == 1) { 762 // Only one region to allocate, try to use a fast path by directly allocating 763 // from the free lists. Do not try to expand here, we will potentially do that 764 // later. 765 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */); 766 if (hr != NULL) { 767 first = hr->hrm_index(); 768 } 769 } else { 770 // We can't allocate humongous regions spanning more than one region while 771 // cleanupComplete() is running, since some of the regions we find to be 772 // empty might not yet be added to the free list. It is not straightforward 773 // to know in which list they are on so that we can remove them. We only 774 // need to do this if we need to allocate more than one region to satisfy the 775 // current humongous allocation request. If we are only allocating one region 776 // we use the one-region region allocation code (see above), that already 777 // potentially waits for regions from the secondary free list. 778 wait_while_free_regions_coming(); 779 append_secondary_free_list_if_not_empty_with_lock(); 780 781 // Policy: Try only empty regions (i.e. already committed first). Maybe we 782 // are lucky enough to find some. 783 first = _hrm.find_contiguous_only_empty(obj_regions); 784 if (first != G1_NO_HRM_INDEX) { 785 _hrm.allocate_free_regions_starting_at(first, obj_regions); 786 } 787 } 788 789 if (first == G1_NO_HRM_INDEX) { 790 // Policy: We could not find enough regions for the humongous object in the 791 // free list. Look through the heap to find a mix of free and uncommitted regions. 792 // If so, try expansion. 793 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions); 794 if (first != G1_NO_HRM_INDEX) { 795 // We found something. Make sure these regions are committed, i.e. expand 796 // the heap. Alternatively we could do a defragmentation GC. 797 ergo_verbose1(ErgoHeapSizing, 798 "attempt heap expansion", 799 ergo_format_reason("humongous allocation request failed") 800 ergo_format_byte("allocation request"), 801 word_size * HeapWordSize); 802 803 _hrm.expand_at(first, obj_regions); 804 g1_policy()->record_new_heap_size(num_regions()); 805 806 #ifdef ASSERT 807 for (uint i = first; i < first + obj_regions; ++i) { 808 HeapRegion* hr = region_at(i); 809 assert(hr->is_free(), "sanity"); 810 assert(hr->is_empty(), "sanity"); 811 assert(is_on_master_free_list(hr), "sanity"); 812 } 813 #endif 814 _hrm.allocate_free_regions_starting_at(first, obj_regions); 815 } else { 816 // Policy: Potentially trigger a defragmentation GC. 817 } 818 } 819 820 HeapWord* result = NULL; 821 if (first != G1_NO_HRM_INDEX) { 822 result = humongous_obj_allocate_initialize_regions(first, obj_regions, 823 word_size, context); 824 assert(result != NULL, "it should always return a valid result"); 825 826 // A successful humongous object allocation changes the used space 827 // information of the old generation so we need to recalculate the 828 // sizes and update the jstat counters here. 829 g1mm()->update_sizes(); 830 } 831 832 verify_region_sets_optional(); 833 834 return result; 835 } 836 837 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) { 838 assert_heap_not_locked_and_not_at_safepoint(); 839 assert(!isHumongous(word_size), "we do not allow humongous TLABs"); 840 841 unsigned int dummy_gc_count_before; 842 int dummy_gclocker_retry_count = 0; 843 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count); 844 } 845 846 HeapWord* 847 G1CollectedHeap::mem_allocate(size_t word_size, 848 bool* gc_overhead_limit_was_exceeded) { 849 assert_heap_not_locked_and_not_at_safepoint(); 850 851 // Loop until the allocation is satisfied, or unsatisfied after GC. 852 for (int try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 853 unsigned int gc_count_before; 854 855 HeapWord* result = NULL; 856 if (!isHumongous(word_size)) { 857 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count); 858 } else { 859 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count); 860 } 861 if (result != NULL) { 862 return result; 863 } 864 865 // Create the garbage collection operation... 866 VM_G1CollectForAllocation op(gc_count_before, word_size); 867 op.set_allocation_context(AllocationContext::current()); 868 869 // ...and get the VM thread to execute it. 870 VMThread::execute(&op); 871 872 if (op.prologue_succeeded() && op.pause_succeeded()) { 873 // If the operation was successful we'll return the result even 874 // if it is NULL. If the allocation attempt failed immediately 875 // after a Full GC, it's unlikely we'll be able to allocate now. 876 HeapWord* result = op.result(); 877 if (result != NULL && !isHumongous(word_size)) { 878 // Allocations that take place on VM operations do not do any 879 // card dirtying and we have to do it here. We only have to do 880 // this for non-humongous allocations, though. 881 dirty_young_block(result, word_size); 882 } 883 return result; 884 } else { 885 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 886 return NULL; 887 } 888 assert(op.result() == NULL, 889 "the result should be NULL if the VM op did not succeed"); 890 } 891 892 // Give a warning if we seem to be looping forever. 893 if ((QueuedAllocationWarningCount > 0) && 894 (try_count % QueuedAllocationWarningCount == 0)) { 895 warning("G1CollectedHeap::mem_allocate retries %d times", try_count); 896 } 897 } 898 899 ShouldNotReachHere(); 900 return NULL; 901 } 902 903 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size, 904 AllocationContext_t context, 905 unsigned int *gc_count_before_ret, 906 int* gclocker_retry_count_ret) { 907 // Make sure you read the note in attempt_allocation_humongous(). 908 909 assert_heap_not_locked_and_not_at_safepoint(); 910 assert(!isHumongous(word_size), "attempt_allocation_slow() should not " 911 "be called for humongous allocation requests"); 912 913 // We should only get here after the first-level allocation attempt 914 // (attempt_allocation()) failed to allocate. 915 916 // We will loop until a) we manage to successfully perform the 917 // allocation or b) we successfully schedule a collection which 918 // fails to perform the allocation. b) is the only case when we'll 919 // return NULL. 920 HeapWord* result = NULL; 921 for (int try_count = 1; /* we'll return */; try_count += 1) { 922 bool should_try_gc; 923 unsigned int gc_count_before; 924 925 { 926 MutexLockerEx x(Heap_lock); 927 result = _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size, 928 false /* bot_updates */); 929 if (result != NULL) { 930 return result; 931 } 932 933 // If we reach here, attempt_allocation_locked() above failed to 934 // allocate a new region. So the mutator alloc region should be NULL. 935 assert(_allocator->mutator_alloc_region(context)->get() == NULL, "only way to get here"); 936 937 if (GC_locker::is_active_and_needs_gc()) { 938 if (g1_policy()->can_expand_young_list()) { 939 // No need for an ergo verbose message here, 940 // can_expand_young_list() does this when it returns true. 941 result = _allocator->mutator_alloc_region(context)->attempt_allocation_force(word_size, 942 false /* bot_updates */); 943 if (result != NULL) { 944 return result; 945 } 946 } 947 should_try_gc = false; 948 } else { 949 // The GCLocker may not be active but the GCLocker initiated 950 // GC may not yet have been performed (GCLocker::needs_gc() 951 // returns true). In this case we do not try this GC and 952 // wait until the GCLocker initiated GC is performed, and 953 // then retry the allocation. 954 if (GC_locker::needs_gc()) { 955 should_try_gc = false; 956 } else { 957 // Read the GC count while still holding the Heap_lock. 958 gc_count_before = total_collections(); 959 should_try_gc = true; 960 } 961 } 962 } 963 964 if (should_try_gc) { 965 bool succeeded; 966 result = do_collection_pause(word_size, gc_count_before, &succeeded, 967 GCCause::_g1_inc_collection_pause); 968 if (result != NULL) { 969 assert(succeeded, "only way to get back a non-NULL result"); 970 return result; 971 } 972 973 if (succeeded) { 974 // If we get here we successfully scheduled a collection which 975 // failed to allocate. No point in trying to allocate 976 // further. We'll just return NULL. 977 MutexLockerEx x(Heap_lock); 978 *gc_count_before_ret = total_collections(); 979 return NULL; 980 } 981 } else { 982 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { 983 MutexLockerEx x(Heap_lock); 984 *gc_count_before_ret = total_collections(); 985 return NULL; 986 } 987 // The GCLocker is either active or the GCLocker initiated 988 // GC has not yet been performed. Stall until it is and 989 // then retry the allocation. 990 GC_locker::stall_until_clear(); 991 (*gclocker_retry_count_ret) += 1; 992 } 993 994 // We can reach here if we were unsuccessful in scheduling a 995 // collection (because another thread beat us to it) or if we were 996 // stalled due to the GC locker. In either can we should retry the 997 // allocation attempt in case another thread successfully 998 // performed a collection and reclaimed enough space. We do the 999 // first attempt (without holding the Heap_lock) here and the 1000 // follow-on attempt will be at the start of the next loop 1001 // iteration (after taking the Heap_lock). 1002 result = _allocator->mutator_alloc_region(context)->attempt_allocation(word_size, 1003 false /* bot_updates */); 1004 if (result != NULL) { 1005 return result; 1006 } 1007 1008 // Give a warning if we seem to be looping forever. 1009 if ((QueuedAllocationWarningCount > 0) && 1010 (try_count % QueuedAllocationWarningCount == 0)) { 1011 warning("G1CollectedHeap::attempt_allocation_slow() " 1012 "retries %d times", try_count); 1013 } 1014 } 1015 1016 ShouldNotReachHere(); 1017 return NULL; 1018 } 1019 1020 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size, 1021 unsigned int * gc_count_before_ret, 1022 int* gclocker_retry_count_ret) { 1023 // The structure of this method has a lot of similarities to 1024 // attempt_allocation_slow(). The reason these two were not merged 1025 // into a single one is that such a method would require several "if 1026 // allocation is not humongous do this, otherwise do that" 1027 // conditional paths which would obscure its flow. In fact, an early 1028 // version of this code did use a unified method which was harder to 1029 // follow and, as a result, it had subtle bugs that were hard to 1030 // track down. So keeping these two methods separate allows each to 1031 // be more readable. It will be good to keep these two in sync as 1032 // much as possible. 1033 1034 assert_heap_not_locked_and_not_at_safepoint(); 1035 assert(isHumongous(word_size), "attempt_allocation_humongous() " 1036 "should only be called for humongous allocations"); 1037 1038 // Humongous objects can exhaust the heap quickly, so we should check if we 1039 // need to start a marking cycle at each humongous object allocation. We do 1040 // the check before we do the actual allocation. The reason for doing it 1041 // before the allocation is that we avoid having to keep track of the newly 1042 // allocated memory while we do a GC. 1043 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation", 1044 word_size)) { 1045 collect(GCCause::_g1_humongous_allocation); 1046 } 1047 1048 // We will loop until a) we manage to successfully perform the 1049 // allocation or b) we successfully schedule a collection which 1050 // fails to perform the allocation. b) is the only case when we'll 1051 // return NULL. 1052 HeapWord* result = NULL; 1053 for (int try_count = 1; /* we'll return */; try_count += 1) { 1054 bool should_try_gc; 1055 unsigned int gc_count_before; 1056 1057 { 1058 MutexLockerEx x(Heap_lock); 1059 1060 // Given that humongous objects are not allocated in young 1061 // regions, we'll first try to do the allocation without doing a 1062 // collection hoping that there's enough space in the heap. 1063 result = humongous_obj_allocate(word_size, AllocationContext::current()); 1064 if (result != NULL) { 1065 return result; 1066 } 1067 1068 if (GC_locker::is_active_and_needs_gc()) { 1069 should_try_gc = false; 1070 } else { 1071 // The GCLocker may not be active but the GCLocker initiated 1072 // GC may not yet have been performed (GCLocker::needs_gc() 1073 // returns true). In this case we do not try this GC and 1074 // wait until the GCLocker initiated GC is performed, and 1075 // then retry the allocation. 1076 if (GC_locker::needs_gc()) { 1077 should_try_gc = false; 1078 } else { 1079 // Read the GC count while still holding the Heap_lock. 1080 gc_count_before = total_collections(); 1081 should_try_gc = true; 1082 } 1083 } 1084 } 1085 1086 if (should_try_gc) { 1087 // If we failed to allocate the humongous object, we should try to 1088 // do a collection pause (if we're allowed) in case it reclaims 1089 // enough space for the allocation to succeed after the pause. 1090 1091 bool succeeded; 1092 result = do_collection_pause(word_size, gc_count_before, &succeeded, 1093 GCCause::_g1_humongous_allocation); 1094 if (result != NULL) { 1095 assert(succeeded, "only way to get back a non-NULL result"); 1096 return result; 1097 } 1098 1099 if (succeeded) { 1100 // If we get here we successfully scheduled a collection which 1101 // failed to allocate. No point in trying to allocate 1102 // further. We'll just return NULL. 1103 MutexLockerEx x(Heap_lock); 1104 *gc_count_before_ret = total_collections(); 1105 return NULL; 1106 } 1107 } else { 1108 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { 1109 MutexLockerEx x(Heap_lock); 1110 *gc_count_before_ret = total_collections(); 1111 return NULL; 1112 } 1113 // The GCLocker is either active or the GCLocker initiated 1114 // GC has not yet been performed. Stall until it is and 1115 // then retry the allocation. 1116 GC_locker::stall_until_clear(); 1117 (*gclocker_retry_count_ret) += 1; 1118 } 1119 1120 // We can reach here if we were unsuccessful in scheduling a 1121 // collection (because another thread beat us to it) or if we were 1122 // stalled due to the GC locker. In either can we should retry the 1123 // allocation attempt in case another thread successfully 1124 // performed a collection and reclaimed enough space. Give a 1125 // warning if we seem to be looping forever. 1126 1127 if ((QueuedAllocationWarningCount > 0) && 1128 (try_count % QueuedAllocationWarningCount == 0)) { 1129 warning("G1CollectedHeap::attempt_allocation_humongous() " 1130 "retries %d times", try_count); 1131 } 1132 } 1133 1134 ShouldNotReachHere(); 1135 return NULL; 1136 } 1137 1138 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size, 1139 AllocationContext_t context, 1140 bool expect_null_mutator_alloc_region) { 1141 assert_at_safepoint(true /* should_be_vm_thread */); 1142 assert(_allocator->mutator_alloc_region(context)->get() == NULL || 1143 !expect_null_mutator_alloc_region, 1144 "the current alloc region was unexpectedly found to be non-NULL"); 1145 1146 if (!isHumongous(word_size)) { 1147 return _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size, 1148 false /* bot_updates */); 1149 } else { 1150 HeapWord* result = humongous_obj_allocate(word_size, context); 1151 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) { 1152 g1_policy()->set_initiate_conc_mark_if_possible(); 1153 } 1154 return result; 1155 } 1156 1157 ShouldNotReachHere(); 1158 } 1159 1160 class PostMCRemSetClearClosure: public HeapRegionClosure { 1161 G1CollectedHeap* _g1h; 1162 ModRefBarrierSet* _mr_bs; 1163 public: 1164 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) : 1165 _g1h(g1h), _mr_bs(mr_bs) {} 1166 1167 bool doHeapRegion(HeapRegion* r) { 1168 HeapRegionRemSet* hrrs = r->rem_set(); 1169 1170 if (r->continuesHumongous()) { 1171 // We'll assert that the strong code root list and RSet is empty 1172 assert(hrrs->strong_code_roots_list_length() == 0, "sanity"); 1173 assert(hrrs->occupied() == 0, "RSet should be empty"); 1174 return false; 1175 } 1176 1177 _g1h->reset_gc_time_stamps(r); 1178 hrrs->clear(); 1179 // You might think here that we could clear just the cards 1180 // corresponding to the used region. But no: if we leave a dirty card 1181 // in a region we might allocate into, then it would prevent that card 1182 // from being enqueued, and cause it to be missed. 1183 // Re: the performance cost: we shouldn't be doing full GC anyway! 1184 _mr_bs->clear(MemRegion(r->bottom(), r->end())); 1185 1186 return false; 1187 } 1188 }; 1189 1190 void G1CollectedHeap::clear_rsets_post_compaction() { 1191 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set()); 1192 heap_region_iterate(&rs_clear); 1193 } 1194 1195 class RebuildRSOutOfRegionClosure: public HeapRegionClosure { 1196 G1CollectedHeap* _g1h; 1197 UpdateRSOopClosure _cl; 1198 int _worker_i; 1199 public: 1200 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) : 1201 _cl(g1->g1_rem_set(), worker_i), 1202 _worker_i(worker_i), 1203 _g1h(g1) 1204 { } 1205 1206 bool doHeapRegion(HeapRegion* r) { 1207 if (!r->continuesHumongous()) { 1208 _cl.set_from(r); 1209 r->oop_iterate(&_cl); 1210 } 1211 return false; 1212 } 1213 }; 1214 1215 class ParRebuildRSTask: public AbstractGangTask { 1216 G1CollectedHeap* _g1; 1217 public: 1218 ParRebuildRSTask(G1CollectedHeap* g1) 1219 : AbstractGangTask("ParRebuildRSTask"), 1220 _g1(g1) 1221 { } 1222 1223 void work(uint worker_id) { 1224 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id); 1225 _g1->heap_region_par_iterate_chunked(&rebuild_rs, worker_id, 1226 _g1->workers()->active_workers(), 1227 HeapRegion::RebuildRSClaimValue); 1228 } 1229 }; 1230 1231 class PostCompactionPrinterClosure: public HeapRegionClosure { 1232 private: 1233 G1HRPrinter* _hr_printer; 1234 public: 1235 bool doHeapRegion(HeapRegion* hr) { 1236 assert(!hr->is_young(), "not expecting to find young regions"); 1237 if (hr->is_free()) { 1238 // We only generate output for non-empty regions. 1239 } else if (hr->startsHumongous()) { 1240 if (hr->region_num() == 1) { 1241 // single humongous region 1242 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous); 1243 } else { 1244 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous); 1245 } 1246 } else if (hr->continuesHumongous()) { 1247 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous); 1248 } else if (hr->is_old()) { 1249 _hr_printer->post_compaction(hr, G1HRPrinter::Old); 1250 } else { 1251 ShouldNotReachHere(); 1252 } 1253 return false; 1254 } 1255 1256 PostCompactionPrinterClosure(G1HRPrinter* hr_printer) 1257 : _hr_printer(hr_printer) { } 1258 }; 1259 1260 void G1CollectedHeap::print_hrm_post_compaction() { 1261 PostCompactionPrinterClosure cl(hr_printer()); 1262 heap_region_iterate(&cl); 1263 } 1264 1265 bool G1CollectedHeap::do_collection(bool explicit_gc, 1266 bool clear_all_soft_refs, 1267 size_t word_size) { 1268 assert_at_safepoint(true /* should_be_vm_thread */); 1269 1270 if (GC_locker::check_active_before_gc()) { 1271 return false; 1272 } 1273 1274 STWGCTimer* gc_timer = G1MarkSweep::gc_timer(); 1275 gc_timer->register_gc_start(); 1276 1277 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer(); 1278 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start()); 1279 1280 SvcGCMarker sgcm(SvcGCMarker::FULL); 1281 ResourceMark rm; 1282 1283 print_heap_before_gc(); 1284 trace_heap_before_gc(gc_tracer); 1285 1286 size_t metadata_prev_used = MetaspaceAux::used_bytes(); 1287 1288 verify_region_sets_optional(); 1289 1290 const bool do_clear_all_soft_refs = clear_all_soft_refs || 1291 collector_policy()->should_clear_all_soft_refs(); 1292 1293 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy()); 1294 1295 { 1296 IsGCActiveMark x; 1297 1298 // Timing 1299 assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant"); 1300 gclog_or_tty->date_stamp(G1Log::fine() && PrintGCDateStamps); 1301 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty); 1302 1303 { 1304 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL, gc_tracer->gc_id()); 1305 TraceCollectorStats tcs(g1mm()->full_collection_counters()); 1306 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause()); 1307 1308 double start = os::elapsedTime(); 1309 g1_policy()->record_full_collection_start(); 1310 1311 // Note: When we have a more flexible GC logging framework that 1312 // allows us to add optional attributes to a GC log record we 1313 // could consider timing and reporting how long we wait in the 1314 // following two methods. 1315 wait_while_free_regions_coming(); 1316 // If we start the compaction before the CM threads finish 1317 // scanning the root regions we might trip them over as we'll 1318 // be moving objects / updating references. So let's wait until 1319 // they are done. By telling them to abort, they should complete 1320 // early. 1321 _cm->root_regions()->abort(); 1322 _cm->root_regions()->wait_until_scan_finished(); 1323 append_secondary_free_list_if_not_empty_with_lock(); 1324 1325 gc_prologue(true); 1326 increment_total_collections(true /* full gc */); 1327 increment_old_marking_cycles_started(); 1328 1329 assert(used() == recalculate_used(), "Should be equal"); 1330 1331 verify_before_gc(); 1332 1333 check_bitmaps("Full GC Start"); 1334 pre_full_gc_dump(gc_timer); 1335 1336 COMPILER2_PRESENT(DerivedPointerTable::clear()); 1337 1338 // Disable discovery and empty the discovered lists 1339 // for the CM ref processor. 1340 ref_processor_cm()->disable_discovery(); 1341 ref_processor_cm()->abandon_partial_discovery(); 1342 ref_processor_cm()->verify_no_references_recorded(); 1343 1344 // Abandon current iterations of concurrent marking and concurrent 1345 // refinement, if any are in progress. We have to do this before 1346 // wait_until_scan_finished() below. 1347 concurrent_mark()->abort(); 1348 1349 // Make sure we'll choose a new allocation region afterwards. 1350 _allocator->release_mutator_alloc_region(); 1351 _allocator->abandon_gc_alloc_regions(); 1352 g1_rem_set()->cleanupHRRS(); 1353 1354 // We should call this after we retire any currently active alloc 1355 // regions so that all the ALLOC / RETIRE events are generated 1356 // before the start GC event. 1357 _hr_printer.start_gc(true /* full */, (size_t) total_collections()); 1358 1359 // We may have added regions to the current incremental collection 1360 // set between the last GC or pause and now. We need to clear the 1361 // incremental collection set and then start rebuilding it afresh 1362 // after this full GC. 1363 abandon_collection_set(g1_policy()->inc_cset_head()); 1364 g1_policy()->clear_incremental_cset(); 1365 g1_policy()->stop_incremental_cset_building(); 1366 1367 tear_down_region_sets(false /* free_list_only */); 1368 g1_policy()->set_gcs_are_young(true); 1369 1370 // See the comments in g1CollectedHeap.hpp and 1371 // G1CollectedHeap::ref_processing_init() about 1372 // how reference processing currently works in G1. 1373 1374 // Temporarily make discovery by the STW ref processor single threaded (non-MT). 1375 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false); 1376 1377 // Temporarily clear the STW ref processor's _is_alive_non_header field. 1378 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL); 1379 1380 ref_processor_stw()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/); 1381 ref_processor_stw()->setup_policy(do_clear_all_soft_refs); 1382 1383 // Do collection work 1384 { 1385 HandleMark hm; // Discard invalid handles created during gc 1386 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs); 1387 } 1388 1389 assert(num_free_regions() == 0, "we should not have added any free regions"); 1390 rebuild_region_sets(false /* free_list_only */); 1391 1392 // Enqueue any discovered reference objects that have 1393 // not been removed from the discovered lists. 1394 ref_processor_stw()->enqueue_discovered_references(); 1395 1396 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 1397 1398 MemoryService::track_memory_usage(); 1399 1400 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 1401 ref_processor_stw()->verify_no_references_recorded(); 1402 1403 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 1404 ClassLoaderDataGraph::purge(); 1405 MetaspaceAux::verify_metrics(); 1406 1407 // Note: since we've just done a full GC, concurrent 1408 // marking is no longer active. Therefore we need not 1409 // re-enable reference discovery for the CM ref processor. 1410 // That will be done at the start of the next marking cycle. 1411 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition"); 1412 ref_processor_cm()->verify_no_references_recorded(); 1413 1414 reset_gc_time_stamp(); 1415 // Since everything potentially moved, we will clear all remembered 1416 // sets, and clear all cards. Later we will rebuild remembered 1417 // sets. We will also reset the GC time stamps of the regions. 1418 clear_rsets_post_compaction(); 1419 check_gc_time_stamps(); 1420 1421 // Resize the heap if necessary. 1422 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size); 1423 1424 if (_hr_printer.is_active()) { 1425 // We should do this after we potentially resize the heap so 1426 // that all the COMMIT / UNCOMMIT events are generated before 1427 // the end GC event. 1428 1429 print_hrm_post_compaction(); 1430 _hr_printer.end_gc(true /* full */, (size_t) total_collections()); 1431 } 1432 1433 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 1434 if (hot_card_cache->use_cache()) { 1435 hot_card_cache->reset_card_counts(); 1436 hot_card_cache->reset_hot_cache(); 1437 } 1438 1439 // Rebuild remembered sets of all regions. 1440 if (G1CollectedHeap::use_parallel_gc_threads()) { 1441 uint n_workers = 1442 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 1443 workers()->active_workers(), 1444 Threads::number_of_non_daemon_threads()); 1445 assert(UseDynamicNumberOfGCThreads || 1446 n_workers == workers()->total_workers(), 1447 "If not dynamic should be using all the workers"); 1448 workers()->set_active_workers(n_workers); 1449 // Set parallel threads in the heap (_n_par_threads) only 1450 // before a parallel phase and always reset it to 0 after 1451 // the phase so that the number of parallel threads does 1452 // no get carried forward to a serial phase where there 1453 // may be code that is "possibly_parallel". 1454 set_par_threads(n_workers); 1455 1456 ParRebuildRSTask rebuild_rs_task(this); 1457 assert(check_heap_region_claim_values( 1458 HeapRegion::InitialClaimValue), "sanity check"); 1459 assert(UseDynamicNumberOfGCThreads || 1460 workers()->active_workers() == workers()->total_workers(), 1461 "Unless dynamic should use total workers"); 1462 // Use the most recent number of active workers 1463 assert(workers()->active_workers() > 0, 1464 "Active workers not properly set"); 1465 set_par_threads(workers()->active_workers()); 1466 workers()->run_task(&rebuild_rs_task); 1467 set_par_threads(0); 1468 assert(check_heap_region_claim_values( 1469 HeapRegion::RebuildRSClaimValue), "sanity check"); 1470 reset_heap_region_claim_values(); 1471 } else { 1472 RebuildRSOutOfRegionClosure rebuild_rs(this); 1473 heap_region_iterate(&rebuild_rs); 1474 } 1475 1476 // Rebuild the strong code root lists for each region 1477 rebuild_strong_code_roots(); 1478 1479 if (true) { // FIXME 1480 MetaspaceGC::compute_new_size(); 1481 } 1482 1483 #ifdef TRACESPINNING 1484 ParallelTaskTerminator::print_termination_counts(); 1485 #endif 1486 1487 // Discard all rset updates 1488 JavaThread::dirty_card_queue_set().abandon_logs(); 1489 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty"); 1490 1491 _young_list->reset_sampled_info(); 1492 // At this point there should be no regions in the 1493 // entire heap tagged as young. 1494 assert(check_young_list_empty(true /* check_heap */), 1495 "young list should be empty at this point"); 1496 1497 // Update the number of full collections that have been completed. 1498 increment_old_marking_cycles_completed(false /* concurrent */); 1499 1500 _hrm.verify_optional(); 1501 verify_region_sets_optional(); 1502 1503 verify_after_gc(); 1504 1505 // Clear the previous marking bitmap, if needed for bitmap verification. 1506 // Note we cannot do this when we clear the next marking bitmap in 1507 // ConcurrentMark::abort() above since VerifyDuringGC verifies the 1508 // objects marked during a full GC against the previous bitmap. 1509 // But we need to clear it before calling check_bitmaps below since 1510 // the full GC has compacted objects and updated TAMS but not updated 1511 // the prev bitmap. 1512 if (G1VerifyBitmaps) { 1513 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll(); 1514 } 1515 check_bitmaps("Full GC End"); 1516 1517 // Start a new incremental collection set for the next pause 1518 assert(g1_policy()->collection_set() == NULL, "must be"); 1519 g1_policy()->start_incremental_cset_building(); 1520 1521 clear_cset_fast_test(); 1522 1523 _allocator->init_mutator_alloc_region(); 1524 1525 double end = os::elapsedTime(); 1526 g1_policy()->record_full_collection_end(); 1527 1528 if (G1Log::fine()) { 1529 g1_policy()->print_heap_transition(); 1530 } 1531 1532 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 1533 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 1534 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 1535 // before any GC notifications are raised. 1536 g1mm()->update_sizes(); 1537 1538 gc_epilogue(true); 1539 } 1540 1541 if (G1Log::finer()) { 1542 g1_policy()->print_detailed_heap_transition(true /* full */); 1543 } 1544 1545 print_heap_after_gc(); 1546 trace_heap_after_gc(gc_tracer); 1547 1548 post_full_gc_dump(gc_timer); 1549 1550 gc_timer->register_gc_end(); 1551 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions()); 1552 } 1553 1554 return true; 1555 } 1556 1557 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) { 1558 // do_collection() will return whether it succeeded in performing 1559 // the GC. Currently, there is no facility on the 1560 // do_full_collection() API to notify the caller than the collection 1561 // did not succeed (e.g., because it was locked out by the GC 1562 // locker). So, right now, we'll ignore the return value. 1563 bool dummy = do_collection(true, /* explicit_gc */ 1564 clear_all_soft_refs, 1565 0 /* word_size */); 1566 } 1567 1568 // This code is mostly copied from TenuredGeneration. 1569 void 1570 G1CollectedHeap:: 1571 resize_if_necessary_after_full_collection(size_t word_size) { 1572 // Include the current allocation, if any, and bytes that will be 1573 // pre-allocated to support collections, as "used". 1574 const size_t used_after_gc = used(); 1575 const size_t capacity_after_gc = capacity(); 1576 const size_t free_after_gc = capacity_after_gc - used_after_gc; 1577 1578 // This is enforced in arguments.cpp. 1579 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, 1580 "otherwise the code below doesn't make sense"); 1581 1582 // We don't have floating point command-line arguments 1583 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0; 1584 const double maximum_used_percentage = 1.0 - minimum_free_percentage; 1585 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0; 1586 const double minimum_used_percentage = 1.0 - maximum_free_percentage; 1587 1588 const size_t min_heap_size = collector_policy()->min_heap_byte_size(); 1589 const size_t max_heap_size = collector_policy()->max_heap_byte_size(); 1590 1591 // We have to be careful here as these two calculations can overflow 1592 // 32-bit size_t's. 1593 double used_after_gc_d = (double) used_after_gc; 1594 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage; 1595 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage; 1596 1597 // Let's make sure that they are both under the max heap size, which 1598 // by default will make them fit into a size_t. 1599 double desired_capacity_upper_bound = (double) max_heap_size; 1600 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d, 1601 desired_capacity_upper_bound); 1602 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d, 1603 desired_capacity_upper_bound); 1604 1605 // We can now safely turn them into size_t's. 1606 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d; 1607 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d; 1608 1609 // This assert only makes sense here, before we adjust them 1610 // with respect to the min and max heap size. 1611 assert(minimum_desired_capacity <= maximum_desired_capacity, 1612 err_msg("minimum_desired_capacity = "SIZE_FORMAT", " 1613 "maximum_desired_capacity = "SIZE_FORMAT, 1614 minimum_desired_capacity, maximum_desired_capacity)); 1615 1616 // Should not be greater than the heap max size. No need to adjust 1617 // it with respect to the heap min size as it's a lower bound (i.e., 1618 // we'll try to make the capacity larger than it, not smaller). 1619 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size); 1620 // Should not be less than the heap min size. No need to adjust it 1621 // with respect to the heap max size as it's an upper bound (i.e., 1622 // we'll try to make the capacity smaller than it, not greater). 1623 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size); 1624 1625 if (capacity_after_gc < minimum_desired_capacity) { 1626 // Don't expand unless it's significant 1627 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc; 1628 ergo_verbose4(ErgoHeapSizing, 1629 "attempt heap expansion", 1630 ergo_format_reason("capacity lower than " 1631 "min desired capacity after Full GC") 1632 ergo_format_byte("capacity") 1633 ergo_format_byte("occupancy") 1634 ergo_format_byte_perc("min desired capacity"), 1635 capacity_after_gc, used_after_gc, 1636 minimum_desired_capacity, (double) MinHeapFreeRatio); 1637 expand(expand_bytes); 1638 1639 // No expansion, now see if we want to shrink 1640 } else if (capacity_after_gc > maximum_desired_capacity) { 1641 // Capacity too large, compute shrinking size 1642 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity; 1643 ergo_verbose4(ErgoHeapSizing, 1644 "attempt heap shrinking", 1645 ergo_format_reason("capacity higher than " 1646 "max desired capacity after Full GC") 1647 ergo_format_byte("capacity") 1648 ergo_format_byte("occupancy") 1649 ergo_format_byte_perc("max desired capacity"), 1650 capacity_after_gc, used_after_gc, 1651 maximum_desired_capacity, (double) MaxHeapFreeRatio); 1652 shrink(shrink_bytes); 1653 } 1654 } 1655 1656 1657 HeapWord* 1658 G1CollectedHeap::satisfy_failed_allocation(size_t word_size, 1659 AllocationContext_t context, 1660 bool* succeeded) { 1661 assert_at_safepoint(true /* should_be_vm_thread */); 1662 1663 *succeeded = true; 1664 // Let's attempt the allocation first. 1665 HeapWord* result = 1666 attempt_allocation_at_safepoint(word_size, 1667 context, 1668 false /* expect_null_mutator_alloc_region */); 1669 if (result != NULL) { 1670 assert(*succeeded, "sanity"); 1671 return result; 1672 } 1673 1674 // In a G1 heap, we're supposed to keep allocation from failing by 1675 // incremental pauses. Therefore, at least for now, we'll favor 1676 // expansion over collection. (This might change in the future if we can 1677 // do something smarter than full collection to satisfy a failed alloc.) 1678 result = expand_and_allocate(word_size, context); 1679 if (result != NULL) { 1680 assert(*succeeded, "sanity"); 1681 return result; 1682 } 1683 1684 // Expansion didn't work, we'll try to do a Full GC. 1685 bool gc_succeeded = do_collection(false, /* explicit_gc */ 1686 false, /* clear_all_soft_refs */ 1687 word_size); 1688 if (!gc_succeeded) { 1689 *succeeded = false; 1690 return NULL; 1691 } 1692 1693 // Retry the allocation 1694 result = attempt_allocation_at_safepoint(word_size, 1695 context, 1696 true /* expect_null_mutator_alloc_region */); 1697 if (result != NULL) { 1698 assert(*succeeded, "sanity"); 1699 return result; 1700 } 1701 1702 // Then, try a Full GC that will collect all soft references. 1703 gc_succeeded = do_collection(false, /* explicit_gc */ 1704 true, /* clear_all_soft_refs */ 1705 word_size); 1706 if (!gc_succeeded) { 1707 *succeeded = false; 1708 return NULL; 1709 } 1710 1711 // Retry the allocation once more 1712 result = attempt_allocation_at_safepoint(word_size, 1713 context, 1714 true /* expect_null_mutator_alloc_region */); 1715 if (result != NULL) { 1716 assert(*succeeded, "sanity"); 1717 return result; 1718 } 1719 1720 assert(!collector_policy()->should_clear_all_soft_refs(), 1721 "Flag should have been handled and cleared prior to this point"); 1722 1723 // What else? We might try synchronous finalization later. If the total 1724 // space available is large enough for the allocation, then a more 1725 // complete compaction phase than we've tried so far might be 1726 // appropriate. 1727 assert(*succeeded, "sanity"); 1728 return NULL; 1729 } 1730 1731 // Attempting to expand the heap sufficiently 1732 // to support an allocation of the given "word_size". If 1733 // successful, perform the allocation and return the address of the 1734 // allocated block, or else "NULL". 1735 1736 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) { 1737 assert_at_safepoint(true /* should_be_vm_thread */); 1738 1739 verify_region_sets_optional(); 1740 1741 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes); 1742 ergo_verbose1(ErgoHeapSizing, 1743 "attempt heap expansion", 1744 ergo_format_reason("allocation request failed") 1745 ergo_format_byte("allocation request"), 1746 word_size * HeapWordSize); 1747 if (expand(expand_bytes)) { 1748 _hrm.verify_optional(); 1749 verify_region_sets_optional(); 1750 return attempt_allocation_at_safepoint(word_size, 1751 context, 1752 false /* expect_null_mutator_alloc_region */); 1753 } 1754 return NULL; 1755 } 1756 1757 bool G1CollectedHeap::expand(size_t expand_bytes) { 1758 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); 1759 aligned_expand_bytes = align_size_up(aligned_expand_bytes, 1760 HeapRegion::GrainBytes); 1761 ergo_verbose2(ErgoHeapSizing, 1762 "expand the heap", 1763 ergo_format_byte("requested expansion amount") 1764 ergo_format_byte("attempted expansion amount"), 1765 expand_bytes, aligned_expand_bytes); 1766 1767 if (is_maximal_no_gc()) { 1768 ergo_verbose0(ErgoHeapSizing, 1769 "did not expand the heap", 1770 ergo_format_reason("heap already fully expanded")); 1771 return false; 1772 } 1773 1774 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes); 1775 assert(regions_to_expand > 0, "Must expand by at least one region"); 1776 1777 uint expanded_by = _hrm.expand_by(regions_to_expand); 1778 1779 if (expanded_by > 0) { 1780 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes; 1781 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition"); 1782 g1_policy()->record_new_heap_size(num_regions()); 1783 } else { 1784 ergo_verbose0(ErgoHeapSizing, 1785 "did not expand the heap", 1786 ergo_format_reason("heap expansion operation failed")); 1787 // The expansion of the virtual storage space was unsuccessful. 1788 // Let's see if it was because we ran out of swap. 1789 if (G1ExitOnExpansionFailure && 1790 _hrm.available() >= regions_to_expand) { 1791 // We had head room... 1792 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion"); 1793 } 1794 } 1795 return regions_to_expand > 0; 1796 } 1797 1798 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) { 1799 size_t aligned_shrink_bytes = 1800 ReservedSpace::page_align_size_down(shrink_bytes); 1801 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes, 1802 HeapRegion::GrainBytes); 1803 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes); 1804 1805 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove); 1806 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes; 1807 1808 ergo_verbose3(ErgoHeapSizing, 1809 "shrink the heap", 1810 ergo_format_byte("requested shrinking amount") 1811 ergo_format_byte("aligned shrinking amount") 1812 ergo_format_byte("attempted shrinking amount"), 1813 shrink_bytes, aligned_shrink_bytes, shrunk_bytes); 1814 if (num_regions_removed > 0) { 1815 g1_policy()->record_new_heap_size(num_regions()); 1816 } else { 1817 ergo_verbose0(ErgoHeapSizing, 1818 "did not shrink the heap", 1819 ergo_format_reason("heap shrinking operation failed")); 1820 } 1821 } 1822 1823 void G1CollectedHeap::shrink(size_t shrink_bytes) { 1824 verify_region_sets_optional(); 1825 1826 // We should only reach here at the end of a Full GC which means we 1827 // should not not be holding to any GC alloc regions. The method 1828 // below will make sure of that and do any remaining clean up. 1829 _allocator->abandon_gc_alloc_regions(); 1830 1831 // Instead of tearing down / rebuilding the free lists here, we 1832 // could instead use the remove_all_pending() method on free_list to 1833 // remove only the ones that we need to remove. 1834 tear_down_region_sets(true /* free_list_only */); 1835 shrink_helper(shrink_bytes); 1836 rebuild_region_sets(true /* free_list_only */); 1837 1838 _hrm.verify_optional(); 1839 verify_region_sets_optional(); 1840 } 1841 1842 // Public methods. 1843 1844 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away 1845 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list 1846 #endif // _MSC_VER 1847 1848 1849 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) : 1850 SharedHeap(policy_), 1851 _g1_policy(policy_), 1852 _dirty_card_queue_set(false), 1853 _into_cset_dirty_card_queue_set(false), 1854 _is_alive_closure_cm(this), 1855 _is_alive_closure_stw(this), 1856 _ref_processor_cm(NULL), 1857 _ref_processor_stw(NULL), 1858 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)), 1859 _bot_shared(NULL), 1860 _evac_failure_scan_stack(NULL), 1861 _mark_in_progress(false), 1862 _cg1r(NULL), 1863 _g1mm(NULL), 1864 _refine_cte_cl(NULL), 1865 _full_collection(false), 1866 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()), 1867 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()), 1868 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()), 1869 _humongous_is_live(), 1870 _has_humongous_reclaim_candidates(false), 1871 _free_regions_coming(false), 1872 _young_list(new YoungList(this)), 1873 _gc_time_stamp(0), 1874 _survivor_plab_stats(YoungPLABSize, PLABWeight), 1875 _old_plab_stats(OldPLABSize, PLABWeight), 1876 _expand_heap_after_alloc_failure(true), 1877 _surviving_young_words(NULL), 1878 _old_marking_cycles_started(0), 1879 _old_marking_cycles_completed(0), 1880 _concurrent_cycle_started(false), 1881 _in_cset_fast_test(), 1882 _dirty_cards_region_list(NULL), 1883 _worker_cset_start_region(NULL), 1884 _worker_cset_start_region_time_stamp(NULL), 1885 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()), 1886 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()), 1887 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()), 1888 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) { 1889 1890 _g1h = this; 1891 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) { 1892 vm_exit_during_initialization("Failed necessary allocation."); 1893 } 1894 1895 _allocator = G1Allocator::create_allocator(_g1h); 1896 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2; 1897 1898 int n_queues = MAX2((int)ParallelGCThreads, 1); 1899 _task_queues = new RefToScanQueueSet(n_queues); 1900 1901 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets(); 1902 assert(n_rem_sets > 0, "Invariant."); 1903 1904 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC); 1905 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(unsigned int, n_queues, mtGC); 1906 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC); 1907 1908 for (int i = 0; i < n_queues; i++) { 1909 RefToScanQueue* q = new RefToScanQueue(); 1910 q->initialize(); 1911 _task_queues->register_queue(i, q); 1912 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo(); 1913 } 1914 clear_cset_start_regions(); 1915 1916 // Initialize the G1EvacuationFailureALot counters and flags. 1917 NOT_PRODUCT(reset_evacuation_should_fail();) 1918 1919 guarantee(_task_queues != NULL, "task_queues allocation failure."); 1920 } 1921 1922 jint G1CollectedHeap::initialize() { 1923 CollectedHeap::pre_initialize(); 1924 os::enable_vtime(); 1925 1926 G1Log::init(); 1927 1928 // Necessary to satisfy locking discipline assertions. 1929 1930 MutexLocker x(Heap_lock); 1931 1932 // We have to initialize the printer before committing the heap, as 1933 // it will be used then. 1934 _hr_printer.set_active(G1PrintHeapRegions); 1935 1936 // While there are no constraints in the GC code that HeapWordSize 1937 // be any particular value, there are multiple other areas in the 1938 // system which believe this to be true (e.g. oop->object_size in some 1939 // cases incorrectly returns the size in wordSize units rather than 1940 // HeapWordSize). 1941 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 1942 1943 size_t init_byte_size = collector_policy()->initial_heap_byte_size(); 1944 size_t max_byte_size = collector_policy()->max_heap_byte_size(); 1945 size_t heap_alignment = collector_policy()->heap_alignment(); 1946 1947 // Ensure that the sizes are properly aligned. 1948 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1949 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1950 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap"); 1951 1952 _refine_cte_cl = new RefineCardTableEntryClosure(); 1953 1954 _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl); 1955 1956 // Reserve the maximum. 1957 1958 // When compressed oops are enabled, the preferred heap base 1959 // is calculated by subtracting the requested size from the 1960 // 32Gb boundary and using the result as the base address for 1961 // heap reservation. If the requested size is not aligned to 1962 // HeapRegion::GrainBytes (i.e. the alignment that is passed 1963 // into the ReservedHeapSpace constructor) then the actual 1964 // base of the reserved heap may end up differing from the 1965 // address that was requested (i.e. the preferred heap base). 1966 // If this happens then we could end up using a non-optimal 1967 // compressed oops mode. 1968 1969 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size, 1970 heap_alignment); 1971 1972 // It is important to do this in a way such that concurrent readers can't 1973 // temporarily think something is in the heap. (I've actually seen this 1974 // happen in asserts: DLD.) 1975 _reserved.set_word_size(0); 1976 _reserved.set_start((HeapWord*)heap_rs.base()); 1977 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size())); 1978 1979 // Create the gen rem set (and barrier set) for the entire reserved region. 1980 _rem_set = collector_policy()->create_rem_set(_reserved, 2); 1981 set_barrier_set(rem_set()->bs()); 1982 if (!barrier_set()->is_a(BarrierSet::G1SATBCTLogging)) { 1983 vm_exit_during_initialization("G1 requires a G1SATBLoggingCardTableModRefBS"); 1984 return JNI_ENOMEM; 1985 } 1986 1987 // Also create a G1 rem set. 1988 _g1_rem_set = new G1RemSet(this, g1_barrier_set()); 1989 1990 // Carve out the G1 part of the heap. 1991 1992 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size); 1993 G1RegionToSpaceMapper* heap_storage = 1994 G1RegionToSpaceMapper::create_mapper(g1_rs, 1995 UseLargePages ? os::large_page_size() : os::vm_page_size(), 1996 HeapRegion::GrainBytes, 1997 1, 1998 mtJavaHeap); 1999 heap_storage->set_mapping_changed_listener(&_listener); 2000 2001 // Reserve space for the block offset table. We do not support automatic uncommit 2002 // for the card table at this time. BOT only. 2003 ReservedSpace bot_rs(G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize)); 2004 G1RegionToSpaceMapper* bot_storage = 2005 G1RegionToSpaceMapper::create_mapper(bot_rs, 2006 os::vm_page_size(), 2007 HeapRegion::GrainBytes, 2008 G1BlockOffsetSharedArray::N_bytes, 2009 mtGC); 2010 2011 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize)); 2012 G1RegionToSpaceMapper* cardtable_storage = 2013 G1RegionToSpaceMapper::create_mapper(cardtable_rs, 2014 os::vm_page_size(), 2015 HeapRegion::GrainBytes, 2016 G1BlockOffsetSharedArray::N_bytes, 2017 mtGC); 2018 2019 // Reserve space for the card counts table. 2020 ReservedSpace card_counts_rs(G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize)); 2021 G1RegionToSpaceMapper* card_counts_storage = 2022 G1RegionToSpaceMapper::create_mapper(card_counts_rs, 2023 os::vm_page_size(), 2024 HeapRegion::GrainBytes, 2025 G1BlockOffsetSharedArray::N_bytes, 2026 mtGC); 2027 2028 // Reserve space for prev and next bitmap. 2029 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size()); 2030 2031 ReservedSpace prev_bitmap_rs(ReservedSpace::allocation_align_size_up(bitmap_size)); 2032 G1RegionToSpaceMapper* prev_bitmap_storage = 2033 G1RegionToSpaceMapper::create_mapper(prev_bitmap_rs, 2034 os::vm_page_size(), 2035 HeapRegion::GrainBytes, 2036 CMBitMap::mark_distance(), 2037 mtGC); 2038 2039 ReservedSpace next_bitmap_rs(ReservedSpace::allocation_align_size_up(bitmap_size)); 2040 G1RegionToSpaceMapper* next_bitmap_storage = 2041 G1RegionToSpaceMapper::create_mapper(next_bitmap_rs, 2042 os::vm_page_size(), 2043 HeapRegion::GrainBytes, 2044 CMBitMap::mark_distance(), 2045 mtGC); 2046 2047 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage); 2048 g1_barrier_set()->initialize(cardtable_storage); 2049 // Do later initialization work for concurrent refinement. 2050 _cg1r->init(card_counts_storage); 2051 2052 // 6843694 - ensure that the maximum region index can fit 2053 // in the remembered set structures. 2054 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; 2055 guarantee((max_regions() - 1) <= max_region_idx, "too many regions"); 2056 2057 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; 2058 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); 2059 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region, 2060 "too many cards per region"); 2061 2062 FreeRegionList::set_unrealistically_long_length(max_regions() + 1); 2063 2064 _bot_shared = new G1BlockOffsetSharedArray(_reserved, bot_storage); 2065 2066 _g1h = this; 2067 2068 _in_cset_fast_test.initialize(_hrm.reserved().start(), _hrm.reserved().end(), HeapRegion::GrainBytes); 2069 _humongous_is_live.initialize(_hrm.reserved().start(), _hrm.reserved().end(), HeapRegion::GrainBytes); 2070 2071 // Create the ConcurrentMark data structure and thread. 2072 // (Must do this late, so that "max_regions" is defined.) 2073 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage); 2074 if (_cm == NULL || !_cm->completed_initialization()) { 2075 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark"); 2076 return JNI_ENOMEM; 2077 } 2078 _cmThread = _cm->cmThread(); 2079 2080 // Initialize the from_card cache structure of HeapRegionRemSet. 2081 HeapRegionRemSet::init_heap(max_regions()); 2082 2083 // Now expand into the initial heap size. 2084 if (!expand(init_byte_size)) { 2085 vm_shutdown_during_initialization("Failed to allocate initial heap."); 2086 return JNI_ENOMEM; 2087 } 2088 2089 // Perform any initialization actions delegated to the policy. 2090 g1_policy()->init(); 2091 2092 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon, 2093 SATB_Q_FL_lock, 2094 G1SATBProcessCompletedThreshold, 2095 Shared_SATB_Q_lock); 2096 2097 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl, 2098 DirtyCardQ_CBL_mon, 2099 DirtyCardQ_FL_lock, 2100 concurrent_g1_refine()->yellow_zone(), 2101 concurrent_g1_refine()->red_zone(), 2102 Shared_DirtyCardQ_lock); 2103 2104 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code 2105 DirtyCardQ_CBL_mon, 2106 DirtyCardQ_FL_lock, 2107 -1, // never trigger processing 2108 -1, // no limit on length 2109 Shared_DirtyCardQ_lock, 2110 &JavaThread::dirty_card_queue_set()); 2111 2112 // Initialize the card queue set used to hold cards containing 2113 // references into the collection set. 2114 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code 2115 DirtyCardQ_CBL_mon, 2116 DirtyCardQ_FL_lock, 2117 -1, // never trigger processing 2118 -1, // no limit on length 2119 Shared_DirtyCardQ_lock, 2120 &JavaThread::dirty_card_queue_set()); 2121 2122 // In case we're keeping closure specialization stats, initialize those 2123 // counts and that mechanism. 2124 SpecializationStats::clear(); 2125 2126 // Here we allocate the dummy HeapRegion that is required by the 2127 // G1AllocRegion class. 2128 HeapRegion* dummy_region = _hrm.get_dummy_region(); 2129 2130 // We'll re-use the same region whether the alloc region will 2131 // require BOT updates or not and, if it doesn't, then a non-young 2132 // region will complain that it cannot support allocations without 2133 // BOT updates. So we'll tag the dummy region as eden to avoid that. 2134 dummy_region->set_eden(); 2135 // Make sure it's full. 2136 dummy_region->set_top(dummy_region->end()); 2137 G1AllocRegion::setup(this, dummy_region); 2138 2139 _allocator->init_mutator_alloc_region(); 2140 2141 // Do create of the monitoring and management support so that 2142 // values in the heap have been properly initialized. 2143 _g1mm = new G1MonitoringSupport(this); 2144 2145 G1StringDedup::initialize(); 2146 2147 return JNI_OK; 2148 } 2149 2150 void G1CollectedHeap::stop() { 2151 // Stop all concurrent threads. We do this to make sure these threads 2152 // do not continue to execute and access resources (e.g. gclog_or_tty) 2153 // that are destroyed during shutdown. 2154 _cg1r->stop(); 2155 _cmThread->stop(); 2156 if (G1StringDedup::is_enabled()) { 2157 G1StringDedup::stop(); 2158 } 2159 } 2160 2161 void G1CollectedHeap::clear_humongous_is_live_table() { 2162 guarantee(G1ReclaimDeadHumongousObjectsAtYoungGC, "Should only be called if true"); 2163 _humongous_is_live.clear(); 2164 } 2165 2166 size_t G1CollectedHeap::conservative_max_heap_alignment() { 2167 return HeapRegion::max_region_size(); 2168 } 2169 2170 void G1CollectedHeap::ref_processing_init() { 2171 // Reference processing in G1 currently works as follows: 2172 // 2173 // * There are two reference processor instances. One is 2174 // used to record and process discovered references 2175 // during concurrent marking; the other is used to 2176 // record and process references during STW pauses 2177 // (both full and incremental). 2178 // * Both ref processors need to 'span' the entire heap as 2179 // the regions in the collection set may be dotted around. 2180 // 2181 // * For the concurrent marking ref processor: 2182 // * Reference discovery is enabled at initial marking. 2183 // * Reference discovery is disabled and the discovered 2184 // references processed etc during remarking. 2185 // * Reference discovery is MT (see below). 2186 // * Reference discovery requires a barrier (see below). 2187 // * Reference processing may or may not be MT 2188 // (depending on the value of ParallelRefProcEnabled 2189 // and ParallelGCThreads). 2190 // * A full GC disables reference discovery by the CM 2191 // ref processor and abandons any entries on it's 2192 // discovered lists. 2193 // 2194 // * For the STW processor: 2195 // * Non MT discovery is enabled at the start of a full GC. 2196 // * Processing and enqueueing during a full GC is non-MT. 2197 // * During a full GC, references are processed after marking. 2198 // 2199 // * Discovery (may or may not be MT) is enabled at the start 2200 // of an incremental evacuation pause. 2201 // * References are processed near the end of a STW evacuation pause. 2202 // * For both types of GC: 2203 // * Discovery is atomic - i.e. not concurrent. 2204 // * Reference discovery will not need a barrier. 2205 2206 SharedHeap::ref_processing_init(); 2207 MemRegion mr = reserved_region(); 2208 2209 // Concurrent Mark ref processor 2210 _ref_processor_cm = 2211 new ReferenceProcessor(mr, // span 2212 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2213 // mt processing 2214 (int) ParallelGCThreads, 2215 // degree of mt processing 2216 (ParallelGCThreads > 1) || (ConcGCThreads > 1), 2217 // mt discovery 2218 (int) MAX2(ParallelGCThreads, ConcGCThreads), 2219 // degree of mt discovery 2220 false, 2221 // Reference discovery is not atomic 2222 &_is_alive_closure_cm); 2223 // is alive closure 2224 // (for efficiency/performance) 2225 2226 // STW ref processor 2227 _ref_processor_stw = 2228 new ReferenceProcessor(mr, // span 2229 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2230 // mt processing 2231 MAX2((int)ParallelGCThreads, 1), 2232 // degree of mt processing 2233 (ParallelGCThreads > 1), 2234 // mt discovery 2235 MAX2((int)ParallelGCThreads, 1), 2236 // degree of mt discovery 2237 true, 2238 // Reference discovery is atomic 2239 &_is_alive_closure_stw); 2240 // is alive closure 2241 // (for efficiency/performance) 2242 } 2243 2244 size_t G1CollectedHeap::capacity() const { 2245 return _hrm.length() * HeapRegion::GrainBytes; 2246 } 2247 2248 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) { 2249 assert(!hr->continuesHumongous(), "pre-condition"); 2250 hr->reset_gc_time_stamp(); 2251 if (hr->startsHumongous()) { 2252 uint first_index = hr->hrm_index() + 1; 2253 uint last_index = hr->last_hc_index(); 2254 for (uint i = first_index; i < last_index; i += 1) { 2255 HeapRegion* chr = region_at(i); 2256 assert(chr->continuesHumongous(), "sanity"); 2257 chr->reset_gc_time_stamp(); 2258 } 2259 } 2260 } 2261 2262 #ifndef PRODUCT 2263 class CheckGCTimeStampsHRClosure : public HeapRegionClosure { 2264 private: 2265 unsigned _gc_time_stamp; 2266 bool _failures; 2267 2268 public: 2269 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) : 2270 _gc_time_stamp(gc_time_stamp), _failures(false) { } 2271 2272 virtual bool doHeapRegion(HeapRegion* hr) { 2273 unsigned region_gc_time_stamp = hr->get_gc_time_stamp(); 2274 if (_gc_time_stamp != region_gc_time_stamp) { 2275 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, " 2276 "expected %d", HR_FORMAT_PARAMS(hr), 2277 region_gc_time_stamp, _gc_time_stamp); 2278 _failures = true; 2279 } 2280 return false; 2281 } 2282 2283 bool failures() { return _failures; } 2284 }; 2285 2286 void G1CollectedHeap::check_gc_time_stamps() { 2287 CheckGCTimeStampsHRClosure cl(_gc_time_stamp); 2288 heap_region_iterate(&cl); 2289 guarantee(!cl.failures(), "all GC time stamps should have been reset"); 2290 } 2291 #endif // PRODUCT 2292 2293 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, 2294 DirtyCardQueue* into_cset_dcq, 2295 bool concurrent, 2296 uint worker_i) { 2297 // Clean cards in the hot card cache 2298 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 2299 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq); 2300 2301 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 2302 int n_completed_buffers = 0; 2303 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) { 2304 n_completed_buffers++; 2305 } 2306 g1_policy()->phase_times()->record_update_rs_processed_buffers(worker_i, n_completed_buffers); 2307 dcqs.clear_n_completed_buffers(); 2308 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!"); 2309 } 2310 2311 2312 // Computes the sum of the storage used by the various regions. 2313 size_t G1CollectedHeap::used() const { 2314 return _allocator->used(); 2315 } 2316 2317 size_t G1CollectedHeap::used_unlocked() const { 2318 return _allocator->used_unlocked(); 2319 } 2320 2321 class SumUsedClosure: public HeapRegionClosure { 2322 size_t _used; 2323 public: 2324 SumUsedClosure() : _used(0) {} 2325 bool doHeapRegion(HeapRegion* r) { 2326 if (!r->continuesHumongous()) { 2327 _used += r->used(); 2328 } 2329 return false; 2330 } 2331 size_t result() { return _used; } 2332 }; 2333 2334 size_t G1CollectedHeap::recalculate_used() const { 2335 double recalculate_used_start = os::elapsedTime(); 2336 2337 SumUsedClosure blk; 2338 heap_region_iterate(&blk); 2339 2340 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0); 2341 return blk.result(); 2342 } 2343 2344 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 2345 switch (cause) { 2346 case GCCause::_gc_locker: return GCLockerInvokesConcurrent; 2347 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent; 2348 case GCCause::_g1_humongous_allocation: return true; 2349 case GCCause::_update_allocation_context_stats_inc: return true; 2350 default: return false; 2351 } 2352 } 2353 2354 #ifndef PRODUCT 2355 void G1CollectedHeap::allocate_dummy_regions() { 2356 // Let's fill up most of the region 2357 size_t word_size = HeapRegion::GrainWords - 1024; 2358 // And as a result the region we'll allocate will be humongous. 2359 guarantee(isHumongous(word_size), "sanity"); 2360 2361 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) { 2362 // Let's use the existing mechanism for the allocation 2363 HeapWord* dummy_obj = humongous_obj_allocate(word_size, 2364 AllocationContext::system()); 2365 if (dummy_obj != NULL) { 2366 MemRegion mr(dummy_obj, word_size); 2367 CollectedHeap::fill_with_object(mr); 2368 } else { 2369 // If we can't allocate once, we probably cannot allocate 2370 // again. Let's get out of the loop. 2371 break; 2372 } 2373 } 2374 } 2375 #endif // !PRODUCT 2376 2377 void G1CollectedHeap::increment_old_marking_cycles_started() { 2378 assert(_old_marking_cycles_started == _old_marking_cycles_completed || 2379 _old_marking_cycles_started == _old_marking_cycles_completed + 1, 2380 err_msg("Wrong marking cycle count (started: %d, completed: %d)", 2381 _old_marking_cycles_started, _old_marking_cycles_completed)); 2382 2383 _old_marking_cycles_started++; 2384 } 2385 2386 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) { 2387 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 2388 2389 // We assume that if concurrent == true, then the caller is a 2390 // concurrent thread that was joined the Suspendible Thread 2391 // Set. If there's ever a cheap way to check this, we should add an 2392 // assert here. 2393 2394 // Given that this method is called at the end of a Full GC or of a 2395 // concurrent cycle, and those can be nested (i.e., a Full GC can 2396 // interrupt a concurrent cycle), the number of full collections 2397 // completed should be either one (in the case where there was no 2398 // nesting) or two (when a Full GC interrupted a concurrent cycle) 2399 // behind the number of full collections started. 2400 2401 // This is the case for the inner caller, i.e. a Full GC. 2402 assert(concurrent || 2403 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || 2404 (_old_marking_cycles_started == _old_marking_cycles_completed + 2), 2405 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u " 2406 "is inconsistent with _old_marking_cycles_completed = %u", 2407 _old_marking_cycles_started, _old_marking_cycles_completed)); 2408 2409 // This is the case for the outer caller, i.e. the concurrent cycle. 2410 assert(!concurrent || 2411 (_old_marking_cycles_started == _old_marking_cycles_completed + 1), 2412 err_msg("for outer caller (concurrent cycle): " 2413 "_old_marking_cycles_started = %u " 2414 "is inconsistent with _old_marking_cycles_completed = %u", 2415 _old_marking_cycles_started, _old_marking_cycles_completed)); 2416 2417 _old_marking_cycles_completed += 1; 2418 2419 // We need to clear the "in_progress" flag in the CM thread before 2420 // we wake up any waiters (especially when ExplicitInvokesConcurrent 2421 // is set) so that if a waiter requests another System.gc() it doesn't 2422 // incorrectly see that a marking cycle is still in progress. 2423 if (concurrent) { 2424 _cmThread->clear_in_progress(); 2425 } 2426 2427 // This notify_all() will ensure that a thread that called 2428 // System.gc() with (with ExplicitGCInvokesConcurrent set or not) 2429 // and it's waiting for a full GC to finish will be woken up. It is 2430 // waiting in VM_G1IncCollectionPause::doit_epilogue(). 2431 FullGCCount_lock->notify_all(); 2432 } 2433 2434 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) { 2435 _concurrent_cycle_started = true; 2436 _gc_timer_cm->register_gc_start(start_time); 2437 2438 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start()); 2439 trace_heap_before_gc(_gc_tracer_cm); 2440 } 2441 2442 void G1CollectedHeap::register_concurrent_cycle_end() { 2443 if (_concurrent_cycle_started) { 2444 if (_cm->has_aborted()) { 2445 _gc_tracer_cm->report_concurrent_mode_failure(); 2446 } 2447 2448 _gc_timer_cm->register_gc_end(); 2449 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions()); 2450 2451 _concurrent_cycle_started = false; 2452 } 2453 } 2454 2455 void G1CollectedHeap::trace_heap_after_concurrent_cycle() { 2456 if (_concurrent_cycle_started) { 2457 trace_heap_after_gc(_gc_tracer_cm); 2458 } 2459 } 2460 2461 G1YCType G1CollectedHeap::yc_type() { 2462 bool is_young = g1_policy()->gcs_are_young(); 2463 bool is_initial_mark = g1_policy()->during_initial_mark_pause(); 2464 bool is_during_mark = mark_in_progress(); 2465 2466 if (is_initial_mark) { 2467 return InitialMark; 2468 } else if (is_during_mark) { 2469 return DuringMark; 2470 } else if (is_young) { 2471 return Normal; 2472 } else { 2473 return Mixed; 2474 } 2475 } 2476 2477 void G1CollectedHeap::collect(GCCause::Cause cause) { 2478 assert_heap_not_locked(); 2479 2480 unsigned int gc_count_before; 2481 unsigned int old_marking_count_before; 2482 unsigned int full_gc_count_before; 2483 bool retry_gc; 2484 2485 do { 2486 retry_gc = false; 2487 2488 { 2489 MutexLocker ml(Heap_lock); 2490 2491 // Read the GC count while holding the Heap_lock 2492 gc_count_before = total_collections(); 2493 full_gc_count_before = total_full_collections(); 2494 old_marking_count_before = _old_marking_cycles_started; 2495 } 2496 2497 if (should_do_concurrent_full_gc(cause)) { 2498 // Schedule an initial-mark evacuation pause that will start a 2499 // concurrent cycle. We're setting word_size to 0 which means that 2500 // we are not requesting a post-GC allocation. 2501 VM_G1IncCollectionPause op(gc_count_before, 2502 0, /* word_size */ 2503 true, /* should_initiate_conc_mark */ 2504 g1_policy()->max_pause_time_ms(), 2505 cause); 2506 op.set_allocation_context(AllocationContext::current()); 2507 2508 VMThread::execute(&op); 2509 if (!op.pause_succeeded()) { 2510 if (old_marking_count_before == _old_marking_cycles_started) { 2511 retry_gc = op.should_retry_gc(); 2512 } else { 2513 // A Full GC happened while we were trying to schedule the 2514 // initial-mark GC. No point in starting a new cycle given 2515 // that the whole heap was collected anyway. 2516 } 2517 2518 if (retry_gc) { 2519 if (GC_locker::is_active_and_needs_gc()) { 2520 GC_locker::stall_until_clear(); 2521 } 2522 } 2523 } 2524 } else { 2525 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc 2526 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { 2527 2528 // Schedule a standard evacuation pause. We're setting word_size 2529 // to 0 which means that we are not requesting a post-GC allocation. 2530 VM_G1IncCollectionPause op(gc_count_before, 2531 0, /* word_size */ 2532 false, /* should_initiate_conc_mark */ 2533 g1_policy()->max_pause_time_ms(), 2534 cause); 2535 VMThread::execute(&op); 2536 } else { 2537 // Schedule a Full GC. 2538 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause); 2539 VMThread::execute(&op); 2540 } 2541 } 2542 } while (retry_gc); 2543 } 2544 2545 bool G1CollectedHeap::is_in(const void* p) const { 2546 if (_hrm.reserved().contains(p)) { 2547 // Given that we know that p is in the reserved space, 2548 // heap_region_containing_raw() should successfully 2549 // return the containing region. 2550 HeapRegion* hr = heap_region_containing_raw(p); 2551 return hr->is_in(p); 2552 } else { 2553 return false; 2554 } 2555 } 2556 2557 #ifdef ASSERT 2558 bool G1CollectedHeap::is_in_exact(const void* p) const { 2559 bool contains = reserved_region().contains(p); 2560 bool available = _hrm.is_available(addr_to_region((HeapWord*)p)); 2561 if (contains && available) { 2562 return true; 2563 } else { 2564 return false; 2565 } 2566 } 2567 #endif 2568 2569 // Iteration functions. 2570 2571 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion. 2572 2573 class IterateOopClosureRegionClosure: public HeapRegionClosure { 2574 ExtendedOopClosure* _cl; 2575 public: 2576 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {} 2577 bool doHeapRegion(HeapRegion* r) { 2578 if (!r->continuesHumongous()) { 2579 r->oop_iterate(_cl); 2580 } 2581 return false; 2582 } 2583 }; 2584 2585 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) { 2586 IterateOopClosureRegionClosure blk(cl); 2587 heap_region_iterate(&blk); 2588 } 2589 2590 // Iterates an ObjectClosure over all objects within a HeapRegion. 2591 2592 class IterateObjectClosureRegionClosure: public HeapRegionClosure { 2593 ObjectClosure* _cl; 2594 public: 2595 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} 2596 bool doHeapRegion(HeapRegion* r) { 2597 if (! r->continuesHumongous()) { 2598 r->object_iterate(_cl); 2599 } 2600 return false; 2601 } 2602 }; 2603 2604 void G1CollectedHeap::object_iterate(ObjectClosure* cl) { 2605 IterateObjectClosureRegionClosure blk(cl); 2606 heap_region_iterate(&blk); 2607 } 2608 2609 // Calls a SpaceClosure on a HeapRegion. 2610 2611 class SpaceClosureRegionClosure: public HeapRegionClosure { 2612 SpaceClosure* _cl; 2613 public: 2614 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {} 2615 bool doHeapRegion(HeapRegion* r) { 2616 _cl->do_space(r); 2617 return false; 2618 } 2619 }; 2620 2621 void G1CollectedHeap::space_iterate(SpaceClosure* cl) { 2622 SpaceClosureRegionClosure blk(cl); 2623 heap_region_iterate(&blk); 2624 } 2625 2626 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { 2627 _hrm.iterate(cl); 2628 } 2629 2630 void 2631 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl, 2632 uint worker_id, 2633 uint num_workers, 2634 jint claim_value) const { 2635 _hrm.par_iterate(cl, worker_id, num_workers, claim_value); 2636 } 2637 2638 class ResetClaimValuesClosure: public HeapRegionClosure { 2639 public: 2640 bool doHeapRegion(HeapRegion* r) { 2641 r->set_claim_value(HeapRegion::InitialClaimValue); 2642 return false; 2643 } 2644 }; 2645 2646 void G1CollectedHeap::reset_heap_region_claim_values() { 2647 ResetClaimValuesClosure blk; 2648 heap_region_iterate(&blk); 2649 } 2650 2651 void G1CollectedHeap::reset_cset_heap_region_claim_values() { 2652 ResetClaimValuesClosure blk; 2653 collection_set_iterate(&blk); 2654 } 2655 2656 #ifdef ASSERT 2657 // This checks whether all regions in the heap have the correct claim 2658 // value. I also piggy-backed on this a check to ensure that the 2659 // humongous_start_region() information on "continues humongous" 2660 // regions is correct. 2661 2662 class CheckClaimValuesClosure : public HeapRegionClosure { 2663 private: 2664 jint _claim_value; 2665 uint _failures; 2666 HeapRegion* _sh_region; 2667 2668 public: 2669 CheckClaimValuesClosure(jint claim_value) : 2670 _claim_value(claim_value), _failures(0), _sh_region(NULL) { } 2671 bool doHeapRegion(HeapRegion* r) { 2672 if (r->claim_value() != _claim_value) { 2673 gclog_or_tty->print_cr("Region " HR_FORMAT ", " 2674 "claim value = %d, should be %d", 2675 HR_FORMAT_PARAMS(r), 2676 r->claim_value(), _claim_value); 2677 ++_failures; 2678 } 2679 if (!r->isHumongous()) { 2680 _sh_region = NULL; 2681 } else if (r->startsHumongous()) { 2682 _sh_region = r; 2683 } else if (r->continuesHumongous()) { 2684 if (r->humongous_start_region() != _sh_region) { 2685 gclog_or_tty->print_cr("Region " HR_FORMAT ", " 2686 "HS = "PTR_FORMAT", should be "PTR_FORMAT, 2687 HR_FORMAT_PARAMS(r), 2688 r->humongous_start_region(), 2689 _sh_region); 2690 ++_failures; 2691 } 2692 } 2693 return false; 2694 } 2695 uint failures() { return _failures; } 2696 }; 2697 2698 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) { 2699 CheckClaimValuesClosure cl(claim_value); 2700 heap_region_iterate(&cl); 2701 return cl.failures() == 0; 2702 } 2703 2704 class CheckClaimValuesInCSetHRClosure: public HeapRegionClosure { 2705 private: 2706 jint _claim_value; 2707 uint _failures; 2708 2709 public: 2710 CheckClaimValuesInCSetHRClosure(jint claim_value) : 2711 _claim_value(claim_value), _failures(0) { } 2712 2713 uint failures() { return _failures; } 2714 2715 bool doHeapRegion(HeapRegion* hr) { 2716 assert(hr->in_collection_set(), "how?"); 2717 assert(!hr->isHumongous(), "H-region in CSet"); 2718 if (hr->claim_value() != _claim_value) { 2719 gclog_or_tty->print_cr("CSet Region " HR_FORMAT ", " 2720 "claim value = %d, should be %d", 2721 HR_FORMAT_PARAMS(hr), 2722 hr->claim_value(), _claim_value); 2723 _failures += 1; 2724 } 2725 return false; 2726 } 2727 }; 2728 2729 bool G1CollectedHeap::check_cset_heap_region_claim_values(jint claim_value) { 2730 CheckClaimValuesInCSetHRClosure cl(claim_value); 2731 collection_set_iterate(&cl); 2732 return cl.failures() == 0; 2733 } 2734 #endif // ASSERT 2735 2736 // Clear the cached CSet starting regions and (more importantly) 2737 // the time stamps. Called when we reset the GC time stamp. 2738 void G1CollectedHeap::clear_cset_start_regions() { 2739 assert(_worker_cset_start_region != NULL, "sanity"); 2740 assert(_worker_cset_start_region_time_stamp != NULL, "sanity"); 2741 2742 int n_queues = MAX2((int)ParallelGCThreads, 1); 2743 for (int i = 0; i < n_queues; i++) { 2744 _worker_cset_start_region[i] = NULL; 2745 _worker_cset_start_region_time_stamp[i] = 0; 2746 } 2747 } 2748 2749 // Given the id of a worker, obtain or calculate a suitable 2750 // starting region for iterating over the current collection set. 2751 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) { 2752 assert(get_gc_time_stamp() > 0, "should have been updated by now"); 2753 2754 HeapRegion* result = NULL; 2755 unsigned gc_time_stamp = get_gc_time_stamp(); 2756 2757 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) { 2758 // Cached starting region for current worker was set 2759 // during the current pause - so it's valid. 2760 // Note: the cached starting heap region may be NULL 2761 // (when the collection set is empty). 2762 result = _worker_cset_start_region[worker_i]; 2763 assert(result == NULL || result->in_collection_set(), "sanity"); 2764 return result; 2765 } 2766 2767 // The cached entry was not valid so let's calculate 2768 // a suitable starting heap region for this worker. 2769 2770 // We want the parallel threads to start their collection 2771 // set iteration at different collection set regions to 2772 // avoid contention. 2773 // If we have: 2774 // n collection set regions 2775 // p threads 2776 // Then thread t will start at region floor ((t * n) / p) 2777 2778 result = g1_policy()->collection_set(); 2779 if (G1CollectedHeap::use_parallel_gc_threads()) { 2780 uint cs_size = g1_policy()->cset_region_length(); 2781 uint active_workers = workers()->active_workers(); 2782 assert(UseDynamicNumberOfGCThreads || 2783 active_workers == workers()->total_workers(), 2784 "Unless dynamic should use total workers"); 2785 2786 uint end_ind = (cs_size * worker_i) / active_workers; 2787 uint start_ind = 0; 2788 2789 if (worker_i > 0 && 2790 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) { 2791 // Previous workers starting region is valid 2792 // so let's iterate from there 2793 start_ind = (cs_size * (worker_i - 1)) / active_workers; 2794 result = _worker_cset_start_region[worker_i - 1]; 2795 } 2796 2797 for (uint i = start_ind; i < end_ind; i++) { 2798 result = result->next_in_collection_set(); 2799 } 2800 } 2801 2802 // Note: the calculated starting heap region may be NULL 2803 // (when the collection set is empty). 2804 assert(result == NULL || result->in_collection_set(), "sanity"); 2805 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp, 2806 "should be updated only once per pause"); 2807 _worker_cset_start_region[worker_i] = result; 2808 OrderAccess::storestore(); 2809 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp; 2810 return result; 2811 } 2812 2813 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) { 2814 HeapRegion* r = g1_policy()->collection_set(); 2815 while (r != NULL) { 2816 HeapRegion* next = r->next_in_collection_set(); 2817 if (cl->doHeapRegion(r)) { 2818 cl->incomplete(); 2819 return; 2820 } 2821 r = next; 2822 } 2823 } 2824 2825 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r, 2826 HeapRegionClosure *cl) { 2827 if (r == NULL) { 2828 // The CSet is empty so there's nothing to do. 2829 return; 2830 } 2831 2832 assert(r->in_collection_set(), 2833 "Start region must be a member of the collection set."); 2834 HeapRegion* cur = r; 2835 while (cur != NULL) { 2836 HeapRegion* next = cur->next_in_collection_set(); 2837 if (cl->doHeapRegion(cur) && false) { 2838 cl->incomplete(); 2839 return; 2840 } 2841 cur = next; 2842 } 2843 cur = g1_policy()->collection_set(); 2844 while (cur != r) { 2845 HeapRegion* next = cur->next_in_collection_set(); 2846 if (cl->doHeapRegion(cur) && false) { 2847 cl->incomplete(); 2848 return; 2849 } 2850 cur = next; 2851 } 2852 } 2853 2854 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const { 2855 HeapRegion* result = _hrm.next_region_in_heap(from); 2856 while (result != NULL && result->isHumongous()) { 2857 result = _hrm.next_region_in_heap(result); 2858 } 2859 return result; 2860 } 2861 2862 Space* G1CollectedHeap::space_containing(const void* addr) const { 2863 return heap_region_containing(addr); 2864 } 2865 2866 HeapWord* G1CollectedHeap::block_start(const void* addr) const { 2867 Space* sp = space_containing(addr); 2868 return sp->block_start(addr); 2869 } 2870 2871 size_t G1CollectedHeap::block_size(const HeapWord* addr) const { 2872 Space* sp = space_containing(addr); 2873 return sp->block_size(addr); 2874 } 2875 2876 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { 2877 Space* sp = space_containing(addr); 2878 return sp->block_is_obj(addr); 2879 } 2880 2881 bool G1CollectedHeap::supports_tlab_allocation() const { 2882 return true; 2883 } 2884 2885 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { 2886 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes; 2887 } 2888 2889 size_t G1CollectedHeap::tlab_used(Thread* ignored) const { 2890 return young_list()->eden_used_bytes(); 2891 } 2892 2893 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size 2894 // must be smaller than the humongous object limit. 2895 size_t G1CollectedHeap::max_tlab_size() const { 2896 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment); 2897 } 2898 2899 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { 2900 // Return the remaining space in the cur alloc region, but not less than 2901 // the min TLAB size. 2902 2903 // Also, this value can be at most the humongous object threshold, 2904 // since we can't allow tlabs to grow big enough to accommodate 2905 // humongous objects. 2906 2907 HeapRegion* hr = _allocator->mutator_alloc_region(AllocationContext::current())->get(); 2908 size_t max_tlab = max_tlab_size() * wordSize; 2909 if (hr == NULL) { 2910 return max_tlab; 2911 } else { 2912 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab); 2913 } 2914 } 2915 2916 size_t G1CollectedHeap::max_capacity() const { 2917 return _hrm.reserved().byte_size(); 2918 } 2919 2920 jlong G1CollectedHeap::millis_since_last_gc() { 2921 // assert(false, "NYI"); 2922 return 0; 2923 } 2924 2925 void G1CollectedHeap::prepare_for_verify() { 2926 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) { 2927 ensure_parsability(false); 2928 } 2929 g1_rem_set()->prepare_for_verify(); 2930 } 2931 2932 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr, 2933 VerifyOption vo) { 2934 switch (vo) { 2935 case VerifyOption_G1UsePrevMarking: 2936 return hr->obj_allocated_since_prev_marking(obj); 2937 case VerifyOption_G1UseNextMarking: 2938 return hr->obj_allocated_since_next_marking(obj); 2939 case VerifyOption_G1UseMarkWord: 2940 return false; 2941 default: 2942 ShouldNotReachHere(); 2943 } 2944 return false; // keep some compilers happy 2945 } 2946 2947 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) { 2948 switch (vo) { 2949 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start(); 2950 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start(); 2951 case VerifyOption_G1UseMarkWord: return NULL; 2952 default: ShouldNotReachHere(); 2953 } 2954 return NULL; // keep some compilers happy 2955 } 2956 2957 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) { 2958 switch (vo) { 2959 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj); 2960 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj); 2961 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked(); 2962 default: ShouldNotReachHere(); 2963 } 2964 return false; // keep some compilers happy 2965 } 2966 2967 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) { 2968 switch (vo) { 2969 case VerifyOption_G1UsePrevMarking: return "PTAMS"; 2970 case VerifyOption_G1UseNextMarking: return "NTAMS"; 2971 case VerifyOption_G1UseMarkWord: return "NONE"; 2972 default: ShouldNotReachHere(); 2973 } 2974 return NULL; // keep some compilers happy 2975 } 2976 2977 class VerifyRootsClosure: public OopClosure { 2978 private: 2979 G1CollectedHeap* _g1h; 2980 VerifyOption _vo; 2981 bool _failures; 2982 public: 2983 // _vo == UsePrevMarking -> use "prev" marking information, 2984 // _vo == UseNextMarking -> use "next" marking information, 2985 // _vo == UseMarkWord -> use mark word from object header. 2986 VerifyRootsClosure(VerifyOption vo) : 2987 _g1h(G1CollectedHeap::heap()), 2988 _vo(vo), 2989 _failures(false) { } 2990 2991 bool failures() { return _failures; } 2992 2993 template <class T> void do_oop_nv(T* p) { 2994 T heap_oop = oopDesc::load_heap_oop(p); 2995 if (!oopDesc::is_null(heap_oop)) { 2996 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 2997 if (_g1h->is_obj_dead_cond(obj, _vo)) { 2998 gclog_or_tty->print_cr("Root location "PTR_FORMAT" " 2999 "points to dead obj "PTR_FORMAT, p, (void*) obj); 3000 if (_vo == VerifyOption_G1UseMarkWord) { 3001 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark())); 3002 } 3003 obj->print_on(gclog_or_tty); 3004 _failures = true; 3005 } 3006 } 3007 } 3008 3009 void do_oop(oop* p) { do_oop_nv(p); } 3010 void do_oop(narrowOop* p) { do_oop_nv(p); } 3011 }; 3012 3013 class G1VerifyCodeRootOopClosure: public OopClosure { 3014 G1CollectedHeap* _g1h; 3015 OopClosure* _root_cl; 3016 nmethod* _nm; 3017 VerifyOption _vo; 3018 bool _failures; 3019 3020 template <class T> void do_oop_work(T* p) { 3021 // First verify that this root is live 3022 _root_cl->do_oop(p); 3023 3024 if (!G1VerifyHeapRegionCodeRoots) { 3025 // We're not verifying the code roots attached to heap region. 3026 return; 3027 } 3028 3029 // Don't check the code roots during marking verification in a full GC 3030 if (_vo == VerifyOption_G1UseMarkWord) { 3031 return; 3032 } 3033 3034 // Now verify that the current nmethod (which contains p) is 3035 // in the code root list of the heap region containing the 3036 // object referenced by p. 3037 3038 T heap_oop = oopDesc::load_heap_oop(p); 3039 if (!oopDesc::is_null(heap_oop)) { 3040 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 3041 3042 // Now fetch the region containing the object 3043 HeapRegion* hr = _g1h->heap_region_containing(obj); 3044 HeapRegionRemSet* hrrs = hr->rem_set(); 3045 // Verify that the strong code root list for this region 3046 // contains the nmethod 3047 if (!hrrs->strong_code_roots_list_contains(_nm)) { 3048 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" " 3049 "from nmethod "PTR_FORMAT" not in strong " 3050 "code roots for region ["PTR_FORMAT","PTR_FORMAT")", 3051 p, _nm, hr->bottom(), hr->end()); 3052 _failures = true; 3053 } 3054 } 3055 } 3056 3057 public: 3058 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo): 3059 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {} 3060 3061 void do_oop(oop* p) { do_oop_work(p); } 3062 void do_oop(narrowOop* p) { do_oop_work(p); } 3063 3064 void set_nmethod(nmethod* nm) { _nm = nm; } 3065 bool failures() { return _failures; } 3066 }; 3067 3068 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure { 3069 G1VerifyCodeRootOopClosure* _oop_cl; 3070 3071 public: 3072 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl): 3073 _oop_cl(oop_cl) {} 3074 3075 void do_code_blob(CodeBlob* cb) { 3076 nmethod* nm = cb->as_nmethod_or_null(); 3077 if (nm != NULL) { 3078 _oop_cl->set_nmethod(nm); 3079 nm->oops_do(_oop_cl); 3080 } 3081 } 3082 }; 3083 3084 class YoungRefCounterClosure : public OopClosure { 3085 G1CollectedHeap* _g1h; 3086 int _count; 3087 public: 3088 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {} 3089 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } } 3090 void do_oop(narrowOop* p) { ShouldNotReachHere(); } 3091 3092 int count() { return _count; } 3093 void reset_count() { _count = 0; }; 3094 }; 3095 3096 class VerifyKlassClosure: public KlassClosure { 3097 YoungRefCounterClosure _young_ref_counter_closure; 3098 OopClosure *_oop_closure; 3099 public: 3100 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {} 3101 void do_klass(Klass* k) { 3102 k->oops_do(_oop_closure); 3103 3104 _young_ref_counter_closure.reset_count(); 3105 k->oops_do(&_young_ref_counter_closure); 3106 if (_young_ref_counter_closure.count() > 0) { 3107 guarantee(k->has_modified_oops(), err_msg("Klass %p, has young refs but is not dirty.", k)); 3108 } 3109 } 3110 }; 3111 3112 class VerifyLivenessOopClosure: public OopClosure { 3113 G1CollectedHeap* _g1h; 3114 VerifyOption _vo; 3115 public: 3116 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo): 3117 _g1h(g1h), _vo(vo) 3118 { } 3119 void do_oop(narrowOop *p) { do_oop_work(p); } 3120 void do_oop( oop *p) { do_oop_work(p); } 3121 3122 template <class T> void do_oop_work(T *p) { 3123 oop obj = oopDesc::load_decode_heap_oop(p); 3124 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo), 3125 "Dead object referenced by a not dead object"); 3126 } 3127 }; 3128 3129 class VerifyObjsInRegionClosure: public ObjectClosure { 3130 private: 3131 G1CollectedHeap* _g1h; 3132 size_t _live_bytes; 3133 HeapRegion *_hr; 3134 VerifyOption _vo; 3135 public: 3136 // _vo == UsePrevMarking -> use "prev" marking information, 3137 // _vo == UseNextMarking -> use "next" marking information, 3138 // _vo == UseMarkWord -> use mark word from object header. 3139 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo) 3140 : _live_bytes(0), _hr(hr), _vo(vo) { 3141 _g1h = G1CollectedHeap::heap(); 3142 } 3143 void do_object(oop o) { 3144 VerifyLivenessOopClosure isLive(_g1h, _vo); 3145 assert(o != NULL, "Huh?"); 3146 if (!_g1h->is_obj_dead_cond(o, _vo)) { 3147 // If the object is alive according to the mark word, 3148 // then verify that the marking information agrees. 3149 // Note we can't verify the contra-positive of the 3150 // above: if the object is dead (according to the mark 3151 // word), it may not be marked, or may have been marked 3152 // but has since became dead, or may have been allocated 3153 // since the last marking. 3154 if (_vo == VerifyOption_G1UseMarkWord) { 3155 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch"); 3156 } 3157 3158 o->oop_iterate_no_header(&isLive); 3159 if (!_hr->obj_allocated_since_prev_marking(o)) { 3160 size_t obj_size = o->size(); // Make sure we don't overflow 3161 _live_bytes += (obj_size * HeapWordSize); 3162 } 3163 } 3164 } 3165 size_t live_bytes() { return _live_bytes; } 3166 }; 3167 3168 class PrintObjsInRegionClosure : public ObjectClosure { 3169 HeapRegion *_hr; 3170 G1CollectedHeap *_g1; 3171 public: 3172 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) { 3173 _g1 = G1CollectedHeap::heap(); 3174 }; 3175 3176 void do_object(oop o) { 3177 if (o != NULL) { 3178 HeapWord *start = (HeapWord *) o; 3179 size_t word_sz = o->size(); 3180 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT 3181 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n", 3182 (void*) o, word_sz, 3183 _g1->isMarkedPrev(o), 3184 _g1->isMarkedNext(o), 3185 _hr->obj_allocated_since_prev_marking(o)); 3186 HeapWord *end = start + word_sz; 3187 HeapWord *cur; 3188 int *val; 3189 for (cur = start; cur < end; cur++) { 3190 val = (int *) cur; 3191 gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val); 3192 } 3193 } 3194 } 3195 }; 3196 3197 class VerifyRegionClosure: public HeapRegionClosure { 3198 private: 3199 bool _par; 3200 VerifyOption _vo; 3201 bool _failures; 3202 public: 3203 // _vo == UsePrevMarking -> use "prev" marking information, 3204 // _vo == UseNextMarking -> use "next" marking information, 3205 // _vo == UseMarkWord -> use mark word from object header. 3206 VerifyRegionClosure(bool par, VerifyOption vo) 3207 : _par(par), 3208 _vo(vo), 3209 _failures(false) {} 3210 3211 bool failures() { 3212 return _failures; 3213 } 3214 3215 bool doHeapRegion(HeapRegion* r) { 3216 if (!r->continuesHumongous()) { 3217 bool failures = false; 3218 r->verify(_vo, &failures); 3219 if (failures) { 3220 _failures = true; 3221 } else { 3222 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo); 3223 r->object_iterate(¬_dead_yet_cl); 3224 if (_vo != VerifyOption_G1UseNextMarking) { 3225 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) { 3226 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] " 3227 "max_live_bytes "SIZE_FORMAT" " 3228 "< calculated "SIZE_FORMAT, 3229 r->bottom(), r->end(), 3230 r->max_live_bytes(), 3231 not_dead_yet_cl.live_bytes()); 3232 _failures = true; 3233 } 3234 } else { 3235 // When vo == UseNextMarking we cannot currently do a sanity 3236 // check on the live bytes as the calculation has not been 3237 // finalized yet. 3238 } 3239 } 3240 } 3241 return false; // stop the region iteration if we hit a failure 3242 } 3243 }; 3244 3245 // This is the task used for parallel verification of the heap regions 3246 3247 class G1ParVerifyTask: public AbstractGangTask { 3248 private: 3249 G1CollectedHeap* _g1h; 3250 VerifyOption _vo; 3251 bool _failures; 3252 3253 public: 3254 // _vo == UsePrevMarking -> use "prev" marking information, 3255 // _vo == UseNextMarking -> use "next" marking information, 3256 // _vo == UseMarkWord -> use mark word from object header. 3257 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) : 3258 AbstractGangTask("Parallel verify task"), 3259 _g1h(g1h), 3260 _vo(vo), 3261 _failures(false) { } 3262 3263 bool failures() { 3264 return _failures; 3265 } 3266 3267 void work(uint worker_id) { 3268 HandleMark hm; 3269 VerifyRegionClosure blk(true, _vo); 3270 _g1h->heap_region_par_iterate_chunked(&blk, worker_id, 3271 _g1h->workers()->active_workers(), 3272 HeapRegion::ParVerifyClaimValue); 3273 if (blk.failures()) { 3274 _failures = true; 3275 } 3276 } 3277 }; 3278 3279 void G1CollectedHeap::verify(bool silent, VerifyOption vo) { 3280 if (SafepointSynchronize::is_at_safepoint()) { 3281 assert(Thread::current()->is_VM_thread(), 3282 "Expected to be executed serially by the VM thread at this point"); 3283 3284 if (!silent) { gclog_or_tty->print("Roots "); } 3285 VerifyRootsClosure rootsCl(vo); 3286 VerifyKlassClosure klassCl(this, &rootsCl); 3287 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false); 3288 3289 // We apply the relevant closures to all the oops in the 3290 // system dictionary, class loader data graph, the string table 3291 // and the nmethods in the code cache. 3292 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo); 3293 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl); 3294 3295 process_all_roots(true, // activate StrongRootsScope 3296 SO_AllCodeCache, // roots scanning options 3297 &rootsCl, 3298 &cldCl, 3299 &blobsCl); 3300 3301 bool failures = rootsCl.failures() || codeRootsCl.failures(); 3302 3303 if (vo != VerifyOption_G1UseMarkWord) { 3304 // If we're verifying during a full GC then the region sets 3305 // will have been torn down at the start of the GC. Therefore 3306 // verifying the region sets will fail. So we only verify 3307 // the region sets when not in a full GC. 3308 if (!silent) { gclog_or_tty->print("HeapRegionSets "); } 3309 verify_region_sets(); 3310 } 3311 3312 if (!silent) { gclog_or_tty->print("HeapRegions "); } 3313 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) { 3314 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue), 3315 "sanity check"); 3316 3317 G1ParVerifyTask task(this, vo); 3318 assert(UseDynamicNumberOfGCThreads || 3319 workers()->active_workers() == workers()->total_workers(), 3320 "If not dynamic should be using all the workers"); 3321 int n_workers = workers()->active_workers(); 3322 set_par_threads(n_workers); 3323 workers()->run_task(&task); 3324 set_par_threads(0); 3325 if (task.failures()) { 3326 failures = true; 3327 } 3328 3329 // Checks that the expected amount of parallel work was done. 3330 // The implication is that n_workers is > 0. 3331 assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue), 3332 "sanity check"); 3333 3334 reset_heap_region_claim_values(); 3335 3336 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue), 3337 "sanity check"); 3338 } else { 3339 VerifyRegionClosure blk(false, vo); 3340 heap_region_iterate(&blk); 3341 if (blk.failures()) { 3342 failures = true; 3343 } 3344 } 3345 if (!silent) gclog_or_tty->print("RemSet "); 3346 rem_set()->verify(); 3347 3348 if (G1StringDedup::is_enabled()) { 3349 if (!silent) gclog_or_tty->print("StrDedup "); 3350 G1StringDedup::verify(); 3351 } 3352 3353 if (failures) { 3354 gclog_or_tty->print_cr("Heap:"); 3355 // It helps to have the per-region information in the output to 3356 // help us track down what went wrong. This is why we call 3357 // print_extended_on() instead of print_on(). 3358 print_extended_on(gclog_or_tty); 3359 gclog_or_tty->cr(); 3360 #ifndef PRODUCT 3361 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) { 3362 concurrent_mark()->print_reachable("at-verification-failure", 3363 vo, false /* all */); 3364 } 3365 #endif 3366 gclog_or_tty->flush(); 3367 } 3368 guarantee(!failures, "there should not have been any failures"); 3369 } else { 3370 if (!silent) { 3371 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet"); 3372 if (G1StringDedup::is_enabled()) { 3373 gclog_or_tty->print(", StrDedup"); 3374 } 3375 gclog_or_tty->print(") "); 3376 } 3377 } 3378 } 3379 3380 void G1CollectedHeap::verify(bool silent) { 3381 verify(silent, VerifyOption_G1UsePrevMarking); 3382 } 3383 3384 double G1CollectedHeap::verify(bool guard, const char* msg) { 3385 double verify_time_ms = 0.0; 3386 3387 if (guard && total_collections() >= VerifyGCStartAt) { 3388 double verify_start = os::elapsedTime(); 3389 HandleMark hm; // Discard invalid handles created during verification 3390 prepare_for_verify(); 3391 Universe::verify(VerifyOption_G1UsePrevMarking, msg); 3392 verify_time_ms = (os::elapsedTime() - verify_start) * 1000; 3393 } 3394 3395 return verify_time_ms; 3396 } 3397 3398 void G1CollectedHeap::verify_before_gc() { 3399 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:"); 3400 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms); 3401 } 3402 3403 void G1CollectedHeap::verify_after_gc() { 3404 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:"); 3405 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms); 3406 } 3407 3408 class PrintRegionClosure: public HeapRegionClosure { 3409 outputStream* _st; 3410 public: 3411 PrintRegionClosure(outputStream* st) : _st(st) {} 3412 bool doHeapRegion(HeapRegion* r) { 3413 r->print_on(_st); 3414 return false; 3415 } 3416 }; 3417 3418 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 3419 const HeapRegion* hr, 3420 const VerifyOption vo) const { 3421 switch (vo) { 3422 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); 3423 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); 3424 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked(); 3425 default: ShouldNotReachHere(); 3426 } 3427 return false; // keep some compilers happy 3428 } 3429 3430 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 3431 const VerifyOption vo) const { 3432 switch (vo) { 3433 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); 3434 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); 3435 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked(); 3436 default: ShouldNotReachHere(); 3437 } 3438 return false; // keep some compilers happy 3439 } 3440 3441 void G1CollectedHeap::print_on(outputStream* st) const { 3442 st->print(" %-20s", "garbage-first heap"); 3443 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 3444 capacity()/K, used_unlocked()/K); 3445 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")", 3446 _hrm.reserved().start(), 3447 _hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords, 3448 _hrm.reserved().end()); 3449 st->cr(); 3450 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); 3451 uint young_regions = _young_list->length(); 3452 st->print("%u young (" SIZE_FORMAT "K), ", young_regions, 3453 (size_t) young_regions * HeapRegion::GrainBytes / K); 3454 uint survivor_regions = g1_policy()->recorded_survivor_regions(); 3455 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, 3456 (size_t) survivor_regions * HeapRegion::GrainBytes / K); 3457 st->cr(); 3458 MetaspaceAux::print_on(st); 3459 } 3460 3461 void G1CollectedHeap::print_extended_on(outputStream* st) const { 3462 print_on(st); 3463 3464 // Print the per-region information. 3465 st->cr(); 3466 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), " 3467 "HS=humongous(starts), HC=humongous(continues), " 3468 "CS=collection set, F=free, TS=gc time stamp, " 3469 "PTAMS=previous top-at-mark-start, " 3470 "NTAMS=next top-at-mark-start)"); 3471 PrintRegionClosure blk(st); 3472 heap_region_iterate(&blk); 3473 } 3474 3475 void G1CollectedHeap::print_on_error(outputStream* st) const { 3476 this->CollectedHeap::print_on_error(st); 3477 3478 if (_cm != NULL) { 3479 st->cr(); 3480 _cm->print_on_error(st); 3481 } 3482 } 3483 3484 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const { 3485 if (G1CollectedHeap::use_parallel_gc_threads()) { 3486 workers()->print_worker_threads_on(st); 3487 } 3488 _cmThread->print_on(st); 3489 st->cr(); 3490 _cm->print_worker_threads_on(st); 3491 _cg1r->print_worker_threads_on(st); 3492 if (G1StringDedup::is_enabled()) { 3493 G1StringDedup::print_worker_threads_on(st); 3494 } 3495 } 3496 3497 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { 3498 if (G1CollectedHeap::use_parallel_gc_threads()) { 3499 workers()->threads_do(tc); 3500 } 3501 tc->do_thread(_cmThread); 3502 _cg1r->threads_do(tc); 3503 if (G1StringDedup::is_enabled()) { 3504 G1StringDedup::threads_do(tc); 3505 } 3506 } 3507 3508 void G1CollectedHeap::print_tracing_info() const { 3509 // We'll overload this to mean "trace GC pause statistics." 3510 if (TraceGen0Time || TraceGen1Time) { 3511 // The "G1CollectorPolicy" is keeping track of these stats, so delegate 3512 // to that. 3513 g1_policy()->print_tracing_info(); 3514 } 3515 if (G1SummarizeRSetStats) { 3516 g1_rem_set()->print_summary_info(); 3517 } 3518 if (G1SummarizeConcMark) { 3519 concurrent_mark()->print_summary_info(); 3520 } 3521 g1_policy()->print_yg_surv_rate_info(); 3522 SpecializationStats::print(); 3523 } 3524 3525 #ifndef PRODUCT 3526 // Helpful for debugging RSet issues. 3527 3528 class PrintRSetsClosure : public HeapRegionClosure { 3529 private: 3530 const char* _msg; 3531 size_t _occupied_sum; 3532 3533 public: 3534 bool doHeapRegion(HeapRegion* r) { 3535 HeapRegionRemSet* hrrs = r->rem_set(); 3536 size_t occupied = hrrs->occupied(); 3537 _occupied_sum += occupied; 3538 3539 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT, 3540 HR_FORMAT_PARAMS(r)); 3541 if (occupied == 0) { 3542 gclog_or_tty->print_cr(" RSet is empty"); 3543 } else { 3544 hrrs->print(); 3545 } 3546 gclog_or_tty->print_cr("----------"); 3547 return false; 3548 } 3549 3550 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { 3551 gclog_or_tty->cr(); 3552 gclog_or_tty->print_cr("========================================"); 3553 gclog_or_tty->print_cr("%s", msg); 3554 gclog_or_tty->cr(); 3555 } 3556 3557 ~PrintRSetsClosure() { 3558 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum); 3559 gclog_or_tty->print_cr("========================================"); 3560 gclog_or_tty->cr(); 3561 } 3562 }; 3563 3564 void G1CollectedHeap::print_cset_rsets() { 3565 PrintRSetsClosure cl("Printing CSet RSets"); 3566 collection_set_iterate(&cl); 3567 } 3568 3569 void G1CollectedHeap::print_all_rsets() { 3570 PrintRSetsClosure cl("Printing All RSets");; 3571 heap_region_iterate(&cl); 3572 } 3573 #endif // PRODUCT 3574 3575 G1CollectedHeap* G1CollectedHeap::heap() { 3576 assert(_sh->kind() == CollectedHeap::G1CollectedHeap, 3577 "not a garbage-first heap"); 3578 return _g1h; 3579 } 3580 3581 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) { 3582 // always_do_update_barrier = false; 3583 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 3584 // Fill TLAB's and such 3585 accumulate_statistics_all_tlabs(); 3586 ensure_parsability(true); 3587 3588 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) && 3589 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) { 3590 g1_rem_set()->print_periodic_summary_info("Before GC RS summary"); 3591 } 3592 } 3593 3594 void G1CollectedHeap::gc_epilogue(bool full) { 3595 3596 if (G1SummarizeRSetStats && 3597 (G1SummarizeRSetStatsPeriod > 0) && 3598 // we are at the end of the GC. Total collections has already been increased. 3599 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) { 3600 g1_rem_set()->print_periodic_summary_info("After GC RS summary"); 3601 } 3602 3603 // FIXME: what is this about? 3604 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" 3605 // is set. 3606 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(), 3607 "derived pointer present")); 3608 // always_do_update_barrier = true; 3609 3610 resize_all_tlabs(); 3611 allocation_context_stats().update(full); 3612 3613 // We have just completed a GC. Update the soft reference 3614 // policy with the new heap occupancy 3615 Universe::update_heap_info_at_gc(); 3616 } 3617 3618 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, 3619 unsigned int gc_count_before, 3620 bool* succeeded, 3621 GCCause::Cause gc_cause) { 3622 assert_heap_not_locked_and_not_at_safepoint(); 3623 g1_policy()->record_stop_world_start(); 3624 VM_G1IncCollectionPause op(gc_count_before, 3625 word_size, 3626 false, /* should_initiate_conc_mark */ 3627 g1_policy()->max_pause_time_ms(), 3628 gc_cause); 3629 3630 op.set_allocation_context(AllocationContext::current()); 3631 VMThread::execute(&op); 3632 3633 HeapWord* result = op.result(); 3634 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded(); 3635 assert(result == NULL || ret_succeeded, 3636 "the result should be NULL if the VM did not succeed"); 3637 *succeeded = ret_succeeded; 3638 3639 assert_heap_not_locked(); 3640 return result; 3641 } 3642 3643 void 3644 G1CollectedHeap::doConcurrentMark() { 3645 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); 3646 if (!_cmThread->in_progress()) { 3647 _cmThread->set_started(); 3648 CGC_lock->notify(); 3649 } 3650 } 3651 3652 size_t G1CollectedHeap::pending_card_num() { 3653 size_t extra_cards = 0; 3654 JavaThread *curr = Threads::first(); 3655 while (curr != NULL) { 3656 DirtyCardQueue& dcq = curr->dirty_card_queue(); 3657 extra_cards += dcq.size(); 3658 curr = curr->next(); 3659 } 3660 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 3661 size_t buffer_size = dcqs.buffer_size(); 3662 size_t buffer_num = dcqs.completed_buffers_num(); 3663 3664 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes 3665 // in bytes - not the number of 'entries'. We need to convert 3666 // into a number of cards. 3667 return (buffer_size * buffer_num + extra_cards) / oopSize; 3668 } 3669 3670 size_t G1CollectedHeap::cards_scanned() { 3671 return g1_rem_set()->cardsScanned(); 3672 } 3673 3674 bool G1CollectedHeap::humongous_region_is_always_live(uint index) { 3675 HeapRegion* region = region_at(index); 3676 assert(region->startsHumongous(), "Must start a humongous object"); 3677 return oop(region->bottom())->is_objArray() || !region->rem_set()->is_empty(); 3678 } 3679 3680 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure { 3681 private: 3682 size_t _total_humongous; 3683 size_t _candidate_humongous; 3684 public: 3685 RegisterHumongousWithInCSetFastTestClosure() : _total_humongous(0), _candidate_humongous(0) { 3686 } 3687 3688 virtual bool doHeapRegion(HeapRegion* r) { 3689 if (!r->startsHumongous()) { 3690 return false; 3691 } 3692 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 3693 3694 uint region_idx = r->hrm_index(); 3695 bool is_candidate = !g1h->humongous_region_is_always_live(region_idx); 3696 // Is_candidate already filters out humongous regions with some remembered set. 3697 // This will not lead to humongous object that we mistakenly keep alive because 3698 // during young collection the remembered sets will only be added to. 3699 if (is_candidate) { 3700 g1h->register_humongous_region_with_in_cset_fast_test(region_idx); 3701 _candidate_humongous++; 3702 } 3703 _total_humongous++; 3704 3705 return false; 3706 } 3707 3708 size_t total_humongous() const { return _total_humongous; } 3709 size_t candidate_humongous() const { return _candidate_humongous; } 3710 }; 3711 3712 void G1CollectedHeap::register_humongous_regions_with_in_cset_fast_test() { 3713 if (!G1ReclaimDeadHumongousObjectsAtYoungGC) { 3714 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0, 0); 3715 return; 3716 } 3717 3718 RegisterHumongousWithInCSetFastTestClosure cl; 3719 heap_region_iterate(&cl); 3720 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(cl.total_humongous(), 3721 cl.candidate_humongous()); 3722 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0; 3723 3724 if (_has_humongous_reclaim_candidates) { 3725 clear_humongous_is_live_table(); 3726 } 3727 } 3728 3729 void 3730 G1CollectedHeap::setup_surviving_young_words() { 3731 assert(_surviving_young_words == NULL, "pre-condition"); 3732 uint array_length = g1_policy()->young_cset_region_length(); 3733 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC); 3734 if (_surviving_young_words == NULL) { 3735 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR, 3736 "Not enough space for young surv words summary."); 3737 } 3738 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t)); 3739 #ifdef ASSERT 3740 for (uint i = 0; i < array_length; ++i) { 3741 assert( _surviving_young_words[i] == 0, "memset above" ); 3742 } 3743 #endif // !ASSERT 3744 } 3745 3746 void 3747 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) { 3748 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); 3749 uint array_length = g1_policy()->young_cset_region_length(); 3750 for (uint i = 0; i < array_length; ++i) { 3751 _surviving_young_words[i] += surv_young_words[i]; 3752 } 3753 } 3754 3755 void 3756 G1CollectedHeap::cleanup_surviving_young_words() { 3757 guarantee( _surviving_young_words != NULL, "pre-condition" ); 3758 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words, mtGC); 3759 _surviving_young_words = NULL; 3760 } 3761 3762 #ifdef ASSERT 3763 class VerifyCSetClosure: public HeapRegionClosure { 3764 public: 3765 bool doHeapRegion(HeapRegion* hr) { 3766 // Here we check that the CSet region's RSet is ready for parallel 3767 // iteration. The fields that we'll verify are only manipulated 3768 // when the region is part of a CSet and is collected. Afterwards, 3769 // we reset these fields when we clear the region's RSet (when the 3770 // region is freed) so they are ready when the region is 3771 // re-allocated. The only exception to this is if there's an 3772 // evacuation failure and instead of freeing the region we leave 3773 // it in the heap. In that case, we reset these fields during 3774 // evacuation failure handling. 3775 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification"); 3776 3777 // Here's a good place to add any other checks we'd like to 3778 // perform on CSet regions. 3779 return false; 3780 } 3781 }; 3782 #endif // ASSERT 3783 3784 #if TASKQUEUE_STATS 3785 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) { 3786 st->print_raw_cr("GC Task Stats"); 3787 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); 3788 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); 3789 } 3790 3791 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const { 3792 print_taskqueue_stats_hdr(st); 3793 3794 TaskQueueStats totals; 3795 const int n = workers() != NULL ? workers()->total_workers() : 1; 3796 for (int i = 0; i < n; ++i) { 3797 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr(); 3798 totals += task_queue(i)->stats; 3799 } 3800 st->print_raw("tot "); totals.print(st); st->cr(); 3801 3802 DEBUG_ONLY(totals.verify()); 3803 } 3804 3805 void G1CollectedHeap::reset_taskqueue_stats() { 3806 const int n = workers() != NULL ? workers()->total_workers() : 1; 3807 for (int i = 0; i < n; ++i) { 3808 task_queue(i)->stats.reset(); 3809 } 3810 } 3811 #endif // TASKQUEUE_STATS 3812 3813 void G1CollectedHeap::log_gc_header() { 3814 if (!G1Log::fine()) { 3815 return; 3816 } 3817 3818 gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id()); 3819 3820 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause()) 3821 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)") 3822 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : ""); 3823 3824 gclog_or_tty->print("[%s", (const char*)gc_cause_str); 3825 } 3826 3827 void G1CollectedHeap::log_gc_footer(double pause_time_sec) { 3828 if (!G1Log::fine()) { 3829 return; 3830 } 3831 3832 if (G1Log::finer()) { 3833 if (evacuation_failed()) { 3834 gclog_or_tty->print(" (to-space exhausted)"); 3835 } 3836 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec); 3837 g1_policy()->phase_times()->note_gc_end(); 3838 g1_policy()->phase_times()->print(pause_time_sec); 3839 g1_policy()->print_detailed_heap_transition(); 3840 } else { 3841 if (evacuation_failed()) { 3842 gclog_or_tty->print("--"); 3843 } 3844 g1_policy()->print_heap_transition(); 3845 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec); 3846 } 3847 gclog_or_tty->flush(); 3848 } 3849 3850 bool 3851 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { 3852 assert_at_safepoint(true /* should_be_vm_thread */); 3853 guarantee(!is_gc_active(), "collection is not reentrant"); 3854 3855 if (GC_locker::check_active_before_gc()) { 3856 return false; 3857 } 3858 3859 _gc_timer_stw->register_gc_start(); 3860 3861 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start()); 3862 3863 SvcGCMarker sgcm(SvcGCMarker::MINOR); 3864 ResourceMark rm; 3865 3866 print_heap_before_gc(); 3867 trace_heap_before_gc(_gc_tracer_stw); 3868 3869 verify_region_sets_optional(); 3870 verify_dirty_young_regions(); 3871 3872 // This call will decide whether this pause is an initial-mark 3873 // pause. If it is, during_initial_mark_pause() will return true 3874 // for the duration of this pause. 3875 g1_policy()->decide_on_conc_mark_initiation(); 3876 3877 // We do not allow initial-mark to be piggy-backed on a mixed GC. 3878 assert(!g1_policy()->during_initial_mark_pause() || 3879 g1_policy()->gcs_are_young(), "sanity"); 3880 3881 // We also do not allow mixed GCs during marking. 3882 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity"); 3883 3884 // Record whether this pause is an initial mark. When the current 3885 // thread has completed its logging output and it's safe to signal 3886 // the CM thread, the flag's value in the policy has been reset. 3887 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause(); 3888 3889 // Inner scope for scope based logging, timers, and stats collection 3890 { 3891 EvacuationInfo evacuation_info; 3892 3893 if (g1_policy()->during_initial_mark_pause()) { 3894 // We are about to start a marking cycle, so we increment the 3895 // full collection counter. 3896 increment_old_marking_cycles_started(); 3897 register_concurrent_cycle_start(_gc_timer_stw->gc_start()); 3898 } 3899 3900 _gc_tracer_stw->report_yc_type(yc_type()); 3901 3902 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty); 3903 3904 int active_workers = (G1CollectedHeap::use_parallel_gc_threads() ? 3905 workers()->active_workers() : 1); 3906 double pause_start_sec = os::elapsedTime(); 3907 g1_policy()->phase_times()->note_gc_start(active_workers); 3908 log_gc_header(); 3909 3910 TraceCollectorStats tcs(g1mm()->incremental_collection_counters()); 3911 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause()); 3912 3913 // If the secondary_free_list is not empty, append it to the 3914 // free_list. No need to wait for the cleanup operation to finish; 3915 // the region allocation code will check the secondary_free_list 3916 // and wait if necessary. If the G1StressConcRegionFreeing flag is 3917 // set, skip this step so that the region allocation code has to 3918 // get entries from the secondary_free_list. 3919 if (!G1StressConcRegionFreeing) { 3920 append_secondary_free_list_if_not_empty_with_lock(); 3921 } 3922 3923 assert(check_young_list_well_formed(), "young list should be well formed"); 3924 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue), 3925 "sanity check"); 3926 3927 // Don't dynamically change the number of GC threads this early. A value of 3928 // 0 is used to indicate serial work. When parallel work is done, 3929 // it will be set. 3930 3931 { // Call to jvmpi::post_class_unload_events must occur outside of active GC 3932 IsGCActiveMark x; 3933 3934 gc_prologue(false); 3935 increment_total_collections(false /* full gc */); 3936 increment_gc_time_stamp(); 3937 3938 verify_before_gc(); 3939 check_bitmaps("GC Start"); 3940 3941 COMPILER2_PRESENT(DerivedPointerTable::clear()); 3942 3943 // Please see comment in g1CollectedHeap.hpp and 3944 // G1CollectedHeap::ref_processing_init() to see how 3945 // reference processing currently works in G1. 3946 3947 // Enable discovery in the STW reference processor 3948 ref_processor_stw()->enable_discovery(true /*verify_disabled*/, 3949 true /*verify_no_refs*/); 3950 3951 { 3952 // We want to temporarily turn off discovery by the 3953 // CM ref processor, if necessary, and turn it back on 3954 // on again later if we do. Using a scoped 3955 // NoRefDiscovery object will do this. 3956 NoRefDiscovery no_cm_discovery(ref_processor_cm()); 3957 3958 // Forget the current alloc region (we might even choose it to be part 3959 // of the collection set!). 3960 _allocator->release_mutator_alloc_region(); 3961 3962 // We should call this after we retire the mutator alloc 3963 // region(s) so that all the ALLOC / RETIRE events are generated 3964 // before the start GC event. 3965 _hr_printer.start_gc(false /* full */, (size_t) total_collections()); 3966 3967 // This timing is only used by the ergonomics to handle our pause target. 3968 // It is unclear why this should not include the full pause. We will 3969 // investigate this in CR 7178365. 3970 // 3971 // Preserving the old comment here if that helps the investigation: 3972 // 3973 // The elapsed time induced by the start time below deliberately elides 3974 // the possible verification above. 3975 double sample_start_time_sec = os::elapsedTime(); 3976 3977 #if YOUNG_LIST_VERBOSE 3978 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:"); 3979 _young_list->print(); 3980 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 3981 #endif // YOUNG_LIST_VERBOSE 3982 3983 g1_policy()->record_collection_pause_start(sample_start_time_sec); 3984 3985 double scan_wait_start = os::elapsedTime(); 3986 // We have to wait until the CM threads finish scanning the 3987 // root regions as it's the only way to ensure that all the 3988 // objects on them have been correctly scanned before we start 3989 // moving them during the GC. 3990 bool waited = _cm->root_regions()->wait_until_scan_finished(); 3991 double wait_time_ms = 0.0; 3992 if (waited) { 3993 double scan_wait_end = os::elapsedTime(); 3994 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0; 3995 } 3996 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms); 3997 3998 #if YOUNG_LIST_VERBOSE 3999 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:"); 4000 _young_list->print(); 4001 #endif // YOUNG_LIST_VERBOSE 4002 4003 if (g1_policy()->during_initial_mark_pause()) { 4004 concurrent_mark()->checkpointRootsInitialPre(); 4005 } 4006 4007 #if YOUNG_LIST_VERBOSE 4008 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:"); 4009 _young_list->print(); 4010 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 4011 #endif // YOUNG_LIST_VERBOSE 4012 4013 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info); 4014 4015 register_humongous_regions_with_in_cset_fast_test(); 4016 4017 _cm->note_start_of_gc(); 4018 // We should not verify the per-thread SATB buffers given that 4019 // we have not filtered them yet (we'll do so during the 4020 // GC). We also call this after finalize_cset() to 4021 // ensure that the CSet has been finalized. 4022 _cm->verify_no_cset_oops(true /* verify_stacks */, 4023 true /* verify_enqueued_buffers */, 4024 false /* verify_thread_buffers */, 4025 true /* verify_fingers */); 4026 4027 if (_hr_printer.is_active()) { 4028 HeapRegion* hr = g1_policy()->collection_set(); 4029 while (hr != NULL) { 4030 _hr_printer.cset(hr); 4031 hr = hr->next_in_collection_set(); 4032 } 4033 } 4034 4035 #ifdef ASSERT 4036 VerifyCSetClosure cl; 4037 collection_set_iterate(&cl); 4038 #endif // ASSERT 4039 4040 setup_surviving_young_words(); 4041 4042 // Initialize the GC alloc regions. 4043 _allocator->init_gc_alloc_regions(evacuation_info); 4044 4045 // Actually do the work... 4046 evacuate_collection_set(evacuation_info); 4047 4048 // We do this to mainly verify the per-thread SATB buffers 4049 // (which have been filtered by now) since we didn't verify 4050 // them earlier. No point in re-checking the stacks / enqueued 4051 // buffers given that the CSet has not changed since last time 4052 // we checked. 4053 _cm->verify_no_cset_oops(false /* verify_stacks */, 4054 false /* verify_enqueued_buffers */, 4055 true /* verify_thread_buffers */, 4056 true /* verify_fingers */); 4057 4058 free_collection_set(g1_policy()->collection_set(), evacuation_info); 4059 4060 eagerly_reclaim_humongous_regions(); 4061 4062 g1_policy()->clear_collection_set(); 4063 4064 cleanup_surviving_young_words(); 4065 4066 // Start a new incremental collection set for the next pause. 4067 g1_policy()->start_incremental_cset_building(); 4068 4069 clear_cset_fast_test(); 4070 4071 _young_list->reset_sampled_info(); 4072 4073 // Don't check the whole heap at this point as the 4074 // GC alloc regions from this pause have been tagged 4075 // as survivors and moved on to the survivor list. 4076 // Survivor regions will fail the !is_young() check. 4077 assert(check_young_list_empty(false /* check_heap */), 4078 "young list should be empty"); 4079 4080 #if YOUNG_LIST_VERBOSE 4081 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:"); 4082 _young_list->print(); 4083 #endif // YOUNG_LIST_VERBOSE 4084 4085 g1_policy()->record_survivor_regions(_young_list->survivor_length(), 4086 _young_list->first_survivor_region(), 4087 _young_list->last_survivor_region()); 4088 4089 _young_list->reset_auxilary_lists(); 4090 4091 if (evacuation_failed()) { 4092 _allocator->set_used(recalculate_used()); 4093 uint n_queues = MAX2((int)ParallelGCThreads, 1); 4094 for (uint i = 0; i < n_queues; i++) { 4095 if (_evacuation_failed_info_array[i].has_failed()) { 4096 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]); 4097 } 4098 } 4099 } else { 4100 // The "used" of the the collection set have already been subtracted 4101 // when they were freed. Add in the bytes evacuated. 4102 _allocator->increase_used(g1_policy()->bytes_copied_during_gc()); 4103 } 4104 4105 if (g1_policy()->during_initial_mark_pause()) { 4106 // We have to do this before we notify the CM threads that 4107 // they can start working to make sure that all the 4108 // appropriate initialization is done on the CM object. 4109 concurrent_mark()->checkpointRootsInitialPost(); 4110 set_marking_started(); 4111 // Note that we don't actually trigger the CM thread at 4112 // this point. We do that later when we're sure that 4113 // the current thread has completed its logging output. 4114 } 4115 4116 allocate_dummy_regions(); 4117 4118 #if YOUNG_LIST_VERBOSE 4119 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:"); 4120 _young_list->print(); 4121 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 4122 #endif // YOUNG_LIST_VERBOSE 4123 4124 _allocator->init_mutator_alloc_region(); 4125 4126 { 4127 size_t expand_bytes = g1_policy()->expansion_amount(); 4128 if (expand_bytes > 0) { 4129 size_t bytes_before = capacity(); 4130 // No need for an ergo verbose message here, 4131 // expansion_amount() does this when it returns a value > 0. 4132 if (!expand(expand_bytes)) { 4133 // We failed to expand the heap. Cannot do anything about it. 4134 } 4135 } 4136 } 4137 4138 // We redo the verification but now wrt to the new CSet which 4139 // has just got initialized after the previous CSet was freed. 4140 _cm->verify_no_cset_oops(true /* verify_stacks */, 4141 true /* verify_enqueued_buffers */, 4142 true /* verify_thread_buffers */, 4143 true /* verify_fingers */); 4144 _cm->note_end_of_gc(); 4145 4146 // This timing is only used by the ergonomics to handle our pause target. 4147 // It is unclear why this should not include the full pause. We will 4148 // investigate this in CR 7178365. 4149 double sample_end_time_sec = os::elapsedTime(); 4150 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; 4151 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info); 4152 4153 MemoryService::track_memory_usage(); 4154 4155 // In prepare_for_verify() below we'll need to scan the deferred 4156 // update buffers to bring the RSets up-to-date if 4157 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning 4158 // the update buffers we'll probably need to scan cards on the 4159 // regions we just allocated to (i.e., the GC alloc 4160 // regions). However, during the last GC we called 4161 // set_saved_mark() on all the GC alloc regions, so card 4162 // scanning might skip the [saved_mark_word()...top()] area of 4163 // those regions (i.e., the area we allocated objects into 4164 // during the last GC). But it shouldn't. Given that 4165 // saved_mark_word() is conditional on whether the GC time stamp 4166 // on the region is current or not, by incrementing the GC time 4167 // stamp here we invalidate all the GC time stamps on all the 4168 // regions and saved_mark_word() will simply return top() for 4169 // all the regions. This is a nicer way of ensuring this rather 4170 // than iterating over the regions and fixing them. In fact, the 4171 // GC time stamp increment here also ensures that 4172 // saved_mark_word() will return top() between pauses, i.e., 4173 // during concurrent refinement. So we don't need the 4174 // is_gc_active() check to decided which top to use when 4175 // scanning cards (see CR 7039627). 4176 increment_gc_time_stamp(); 4177 4178 verify_after_gc(); 4179 check_bitmaps("GC End"); 4180 4181 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 4182 ref_processor_stw()->verify_no_references_recorded(); 4183 4184 // CM reference discovery will be re-enabled if necessary. 4185 } 4186 4187 // We should do this after we potentially expand the heap so 4188 // that all the COMMIT events are generated before the end GC 4189 // event, and after we retire the GC alloc regions so that all 4190 // RETIRE events are generated before the end GC event. 4191 _hr_printer.end_gc(false /* full */, (size_t) total_collections()); 4192 4193 #ifdef TRACESPINNING 4194 ParallelTaskTerminator::print_termination_counts(); 4195 #endif 4196 4197 gc_epilogue(false); 4198 } 4199 4200 // Print the remainder of the GC log output. 4201 log_gc_footer(os::elapsedTime() - pause_start_sec); 4202 4203 // It is not yet to safe to tell the concurrent mark to 4204 // start as we have some optional output below. We don't want the 4205 // output from the concurrent mark thread interfering with this 4206 // logging output either. 4207 4208 _hrm.verify_optional(); 4209 verify_region_sets_optional(); 4210 4211 TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats()); 4212 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); 4213 4214 print_heap_after_gc(); 4215 trace_heap_after_gc(_gc_tracer_stw); 4216 4217 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 4218 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 4219 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 4220 // before any GC notifications are raised. 4221 g1mm()->update_sizes(); 4222 4223 _gc_tracer_stw->report_evacuation_info(&evacuation_info); 4224 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold()); 4225 _gc_timer_stw->register_gc_end(); 4226 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions()); 4227 } 4228 // It should now be safe to tell the concurrent mark thread to start 4229 // without its logging output interfering with the logging output 4230 // that came from the pause. 4231 4232 if (should_start_conc_mark) { 4233 // CAUTION: after the doConcurrentMark() call below, 4234 // the concurrent marking thread(s) could be running 4235 // concurrently with us. Make sure that anything after 4236 // this point does not assume that we are the only GC thread 4237 // running. Note: of course, the actual marking work will 4238 // not start until the safepoint itself is released in 4239 // SuspendibleThreadSet::desynchronize(). 4240 doConcurrentMark(); 4241 } 4242 4243 return true; 4244 } 4245 4246 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose) 4247 { 4248 size_t gclab_word_size; 4249 switch (purpose) { 4250 case GCAllocForSurvived: 4251 gclab_word_size = _survivor_plab_stats.desired_plab_sz(); 4252 break; 4253 case GCAllocForTenured: 4254 gclab_word_size = _old_plab_stats.desired_plab_sz(); 4255 break; 4256 default: 4257 assert(false, "unknown GCAllocPurpose"); 4258 gclab_word_size = _old_plab_stats.desired_plab_sz(); 4259 break; 4260 } 4261 4262 // Prevent humongous PLAB sizes for two reasons: 4263 // * PLABs are allocated using a similar paths as oops, but should 4264 // never be in a humongous region 4265 // * Allowing humongous PLABs needlessly churns the region free lists 4266 return MIN2(_humongous_object_threshold_in_words, gclab_word_size); 4267 } 4268 4269 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) { 4270 _drain_in_progress = false; 4271 set_evac_failure_closure(cl); 4272 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true); 4273 } 4274 4275 void G1CollectedHeap::finalize_for_evac_failure() { 4276 assert(_evac_failure_scan_stack != NULL && 4277 _evac_failure_scan_stack->length() == 0, 4278 "Postcondition"); 4279 assert(!_drain_in_progress, "Postcondition"); 4280 delete _evac_failure_scan_stack; 4281 _evac_failure_scan_stack = NULL; 4282 } 4283 4284 void G1CollectedHeap::remove_self_forwarding_pointers() { 4285 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity"); 4286 4287 double remove_self_forwards_start = os::elapsedTime(); 4288 4289 G1ParRemoveSelfForwardPtrsTask rsfp_task(this); 4290 4291 if (G1CollectedHeap::use_parallel_gc_threads()) { 4292 set_par_threads(); 4293 workers()->run_task(&rsfp_task); 4294 set_par_threads(0); 4295 } else { 4296 rsfp_task.work(0); 4297 } 4298 4299 assert(check_cset_heap_region_claim_values(HeapRegion::ParEvacFailureClaimValue), "sanity"); 4300 4301 // Reset the claim values in the regions in the collection set. 4302 reset_cset_heap_region_claim_values(); 4303 4304 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity"); 4305 4306 // Now restore saved marks, if any. 4307 assert(_objs_with_preserved_marks.size() == 4308 _preserved_marks_of_objs.size(), "Both or none."); 4309 while (!_objs_with_preserved_marks.is_empty()) { 4310 oop obj = _objs_with_preserved_marks.pop(); 4311 markOop m = _preserved_marks_of_objs.pop(); 4312 obj->set_mark(m); 4313 } 4314 _objs_with_preserved_marks.clear(true); 4315 _preserved_marks_of_objs.clear(true); 4316 4317 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0); 4318 } 4319 4320 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) { 4321 _evac_failure_scan_stack->push(obj); 4322 } 4323 4324 void G1CollectedHeap::drain_evac_failure_scan_stack() { 4325 assert(_evac_failure_scan_stack != NULL, "precondition"); 4326 4327 while (_evac_failure_scan_stack->length() > 0) { 4328 oop obj = _evac_failure_scan_stack->pop(); 4329 _evac_failure_closure->set_region(heap_region_containing(obj)); 4330 obj->oop_iterate_backwards(_evac_failure_closure); 4331 } 4332 } 4333 4334 oop 4335 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state, 4336 oop old) { 4337 assert(obj_in_cs(old), 4338 err_msg("obj: "PTR_FORMAT" should still be in the CSet", 4339 (HeapWord*) old)); 4340 markOop m = old->mark(); 4341 oop forward_ptr = old->forward_to_atomic(old); 4342 if (forward_ptr == NULL) { 4343 // Forward-to-self succeeded. 4344 assert(_par_scan_state != NULL, "par scan state"); 4345 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure(); 4346 uint queue_num = _par_scan_state->queue_num(); 4347 4348 _evacuation_failed = true; 4349 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size()); 4350 if (_evac_failure_closure != cl) { 4351 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag); 4352 assert(!_drain_in_progress, 4353 "Should only be true while someone holds the lock."); 4354 // Set the global evac-failure closure to the current thread's. 4355 assert(_evac_failure_closure == NULL, "Or locking has failed."); 4356 set_evac_failure_closure(cl); 4357 // Now do the common part. 4358 handle_evacuation_failure_common(old, m); 4359 // Reset to NULL. 4360 set_evac_failure_closure(NULL); 4361 } else { 4362 // The lock is already held, and this is recursive. 4363 assert(_drain_in_progress, "This should only be the recursive case."); 4364 handle_evacuation_failure_common(old, m); 4365 } 4366 return old; 4367 } else { 4368 // Forward-to-self failed. Either someone else managed to allocate 4369 // space for this object (old != forward_ptr) or they beat us in 4370 // self-forwarding it (old == forward_ptr). 4371 assert(old == forward_ptr || !obj_in_cs(forward_ptr), 4372 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" " 4373 "should not be in the CSet", 4374 (HeapWord*) old, (HeapWord*) forward_ptr)); 4375 return forward_ptr; 4376 } 4377 } 4378 4379 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) { 4380 preserve_mark_if_necessary(old, m); 4381 4382 HeapRegion* r = heap_region_containing(old); 4383 if (!r->evacuation_failed()) { 4384 r->set_evacuation_failed(true); 4385 _hr_printer.evac_failure(r); 4386 } 4387 4388 push_on_evac_failure_scan_stack(old); 4389 4390 if (!_drain_in_progress) { 4391 // prevent recursion in copy_to_survivor_space() 4392 _drain_in_progress = true; 4393 drain_evac_failure_scan_stack(); 4394 _drain_in_progress = false; 4395 } 4396 } 4397 4398 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) { 4399 assert(evacuation_failed(), "Oversaving!"); 4400 // We want to call the "for_promotion_failure" version only in the 4401 // case of a promotion failure. 4402 if (m->must_be_preserved_for_promotion_failure(obj)) { 4403 _objs_with_preserved_marks.push(obj); 4404 _preserved_marks_of_objs.push(m); 4405 } 4406 } 4407 4408 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose, 4409 size_t word_size, 4410 AllocationContext_t context) { 4411 if (purpose == GCAllocForSurvived) { 4412 HeapWord* result = survivor_attempt_allocation(word_size, context); 4413 if (result != NULL) { 4414 return result; 4415 } else { 4416 // Let's try to allocate in the old gen in case we can fit the 4417 // object there. 4418 return old_attempt_allocation(word_size, context); 4419 } 4420 } else { 4421 assert(purpose == GCAllocForTenured, "sanity"); 4422 HeapWord* result = old_attempt_allocation(word_size, context); 4423 if (result != NULL) { 4424 return result; 4425 } else { 4426 // Let's try to allocate in the survivors in case we can fit the 4427 // object there. 4428 return survivor_attempt_allocation(word_size, context); 4429 } 4430 } 4431 4432 ShouldNotReachHere(); 4433 // Trying to keep some compilers happy. 4434 return NULL; 4435 } 4436 4437 void G1ParCopyHelper::mark_object(oop obj) { 4438 assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet"); 4439 4440 // We know that the object is not moving so it's safe to read its size. 4441 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id); 4442 } 4443 4444 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) { 4445 assert(from_obj->is_forwarded(), "from obj should be forwarded"); 4446 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee"); 4447 assert(from_obj != to_obj, "should not be self-forwarded"); 4448 4449 assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet"); 4450 assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet"); 4451 4452 // The object might be in the process of being copied by another 4453 // worker so we cannot trust that its to-space image is 4454 // well-formed. So we have to read its size from its from-space 4455 // image which we know should not be changing. 4456 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id); 4457 } 4458 4459 template <class T> 4460 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) { 4461 if (_g1->heap_region_containing_raw(new_obj)->is_young()) { 4462 _scanned_klass->record_modified_oops(); 4463 } 4464 } 4465 4466 template <G1Barrier barrier, G1Mark do_mark_object> 4467 template <class T> 4468 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) { 4469 T heap_oop = oopDesc::load_heap_oop(p); 4470 4471 if (oopDesc::is_null(heap_oop)) { 4472 return; 4473 } 4474 4475 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 4476 4477 assert(_worker_id == _par_scan_state->queue_num(), "sanity"); 4478 4479 G1CollectedHeap::in_cset_state_t state = _g1->in_cset_state(obj); 4480 4481 if (state == G1CollectedHeap::InCSet) { 4482 oop forwardee; 4483 if (obj->is_forwarded()) { 4484 forwardee = obj->forwardee(); 4485 } else { 4486 forwardee = _par_scan_state->copy_to_survivor_space(obj); 4487 } 4488 assert(forwardee != NULL, "forwardee should not be NULL"); 4489 oopDesc::encode_store_heap_oop(p, forwardee); 4490 if (do_mark_object != G1MarkNone && forwardee != obj) { 4491 // If the object is self-forwarded we don't need to explicitly 4492 // mark it, the evacuation failure protocol will do so. 4493 mark_forwarded_object(obj, forwardee); 4494 } 4495 4496 if (barrier == G1BarrierKlass) { 4497 do_klass_barrier(p, forwardee); 4498 } 4499 } else { 4500 if (state == G1CollectedHeap::IsHumongous) { 4501 _g1->set_humongous_is_live(obj); 4502 } 4503 // The object is not in collection set. If we're a root scanning 4504 // closure during an initial mark pause then attempt to mark the object. 4505 if (do_mark_object == G1MarkFromRoot) { 4506 mark_object(obj); 4507 } 4508 } 4509 4510 if (barrier == G1BarrierEvac) { 4511 _par_scan_state->update_rs(_from, p, _worker_id); 4512 } 4513 } 4514 4515 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(oop* p); 4516 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(narrowOop* p); 4517 4518 class G1ParEvacuateFollowersClosure : public VoidClosure { 4519 protected: 4520 G1CollectedHeap* _g1h; 4521 G1ParScanThreadState* _par_scan_state; 4522 RefToScanQueueSet* _queues; 4523 ParallelTaskTerminator* _terminator; 4524 4525 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 4526 RefToScanQueueSet* queues() { return _queues; } 4527 ParallelTaskTerminator* terminator() { return _terminator; } 4528 4529 public: 4530 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h, 4531 G1ParScanThreadState* par_scan_state, 4532 RefToScanQueueSet* queues, 4533 ParallelTaskTerminator* terminator) 4534 : _g1h(g1h), _par_scan_state(par_scan_state), 4535 _queues(queues), _terminator(terminator) {} 4536 4537 void do_void(); 4538 4539 private: 4540 inline bool offer_termination(); 4541 }; 4542 4543 bool G1ParEvacuateFollowersClosure::offer_termination() { 4544 G1ParScanThreadState* const pss = par_scan_state(); 4545 pss->start_term_time(); 4546 const bool res = terminator()->offer_termination(); 4547 pss->end_term_time(); 4548 return res; 4549 } 4550 4551 void G1ParEvacuateFollowersClosure::do_void() { 4552 G1ParScanThreadState* const pss = par_scan_state(); 4553 pss->trim_queue(); 4554 do { 4555 pss->steal_and_trim_queue(queues()); 4556 } while (!offer_termination()); 4557 } 4558 4559 class G1KlassScanClosure : public KlassClosure { 4560 G1ParCopyHelper* _closure; 4561 bool _process_only_dirty; 4562 int _count; 4563 public: 4564 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty) 4565 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {} 4566 void do_klass(Klass* klass) { 4567 // If the klass has not been dirtied we know that there's 4568 // no references into the young gen and we can skip it. 4569 if (!_process_only_dirty || klass->has_modified_oops()) { 4570 // Clean the klass since we're going to scavenge all the metadata. 4571 klass->clear_modified_oops(); 4572 4573 // Tell the closure that this klass is the Klass to scavenge 4574 // and is the one to dirty if oops are left pointing into the young gen. 4575 _closure->set_scanned_klass(klass); 4576 4577 klass->oops_do(_closure); 4578 4579 _closure->set_scanned_klass(NULL); 4580 } 4581 _count++; 4582 } 4583 }; 4584 4585 class G1CodeBlobClosure : public CodeBlobClosure { 4586 class HeapRegionGatheringOopClosure : public OopClosure { 4587 G1CollectedHeap* _g1h; 4588 OopClosure* _work; 4589 nmethod* _nm; 4590 4591 template <typename T> 4592 void do_oop_work(T* p) { 4593 _work->do_oop(p); 4594 T oop_or_narrowoop = oopDesc::load_heap_oop(p); 4595 if (!oopDesc::is_null(oop_or_narrowoop)) { 4596 oop o = oopDesc::decode_heap_oop_not_null(oop_or_narrowoop); 4597 HeapRegion* hr = _g1h->heap_region_containing_raw(o); 4598 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"); 4599 hr->add_strong_code_root(_nm); 4600 } 4601 } 4602 4603 public: 4604 HeapRegionGatheringOopClosure(OopClosure* oc) : _g1h(G1CollectedHeap::heap()), _work(oc), _nm(NULL) {} 4605 4606 void do_oop(oop* o) { 4607 do_oop_work(o); 4608 } 4609 4610 void do_oop(narrowOop* o) { 4611 do_oop_work(o); 4612 } 4613 4614 void set_nm(nmethod* nm) { 4615 _nm = nm; 4616 } 4617 }; 4618 4619 HeapRegionGatheringOopClosure _oc; 4620 public: 4621 G1CodeBlobClosure(OopClosure* oc) : _oc(oc) {} 4622 4623 void do_code_blob(CodeBlob* cb) { 4624 nmethod* nm = cb->as_nmethod_or_null(); 4625 if (nm != NULL) { 4626 if (!nm->test_set_oops_do_mark()) { 4627 _oc.set_nm(nm); 4628 nm->oops_do(&_oc); 4629 nm->fix_oop_relocations(); 4630 } 4631 } 4632 } 4633 }; 4634 4635 class G1ParTask : public AbstractGangTask { 4636 protected: 4637 G1CollectedHeap* _g1h; 4638 RefToScanQueueSet *_queues; 4639 ParallelTaskTerminator _terminator; 4640 uint _n_workers; 4641 4642 Mutex _stats_lock; 4643 Mutex* stats_lock() { return &_stats_lock; } 4644 4645 public: 4646 G1ParTask(G1CollectedHeap* g1h, RefToScanQueueSet *task_queues) 4647 : AbstractGangTask("G1 collection"), 4648 _g1h(g1h), 4649 _queues(task_queues), 4650 _terminator(0, _queues), 4651 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true) 4652 {} 4653 4654 RefToScanQueueSet* queues() { return _queues; } 4655 4656 RefToScanQueue *work_queue(int i) { 4657 return queues()->queue(i); 4658 } 4659 4660 ParallelTaskTerminator* terminator() { return &_terminator; } 4661 4662 virtual void set_for_termination(int active_workers) { 4663 // This task calls set_n_termination() in par_non_clean_card_iterate_work() 4664 // in the young space (_par_seq_tasks) in the G1 heap 4665 // for SequentialSubTasksDone. 4666 // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap 4667 // both of which need setting by set_n_termination(). 4668 _g1h->SharedHeap::set_n_termination(active_workers); 4669 _g1h->set_n_termination(active_workers); 4670 terminator()->reset_for_reuse(active_workers); 4671 _n_workers = active_workers; 4672 } 4673 4674 // Helps out with CLD processing. 4675 // 4676 // During InitialMark we need to: 4677 // 1) Scavenge all CLDs for the young GC. 4678 // 2) Mark all objects directly reachable from strong CLDs. 4679 template <G1Mark do_mark_object> 4680 class G1CLDClosure : public CLDClosure { 4681 G1ParCopyClosure<G1BarrierNone, do_mark_object>* _oop_closure; 4682 G1ParCopyClosure<G1BarrierKlass, do_mark_object> _oop_in_klass_closure; 4683 G1KlassScanClosure _klass_in_cld_closure; 4684 bool _claim; 4685 4686 public: 4687 G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure, 4688 bool only_young, bool claim) 4689 : _oop_closure(oop_closure), 4690 _oop_in_klass_closure(oop_closure->g1(), 4691 oop_closure->pss(), 4692 oop_closure->rp()), 4693 _klass_in_cld_closure(&_oop_in_klass_closure, only_young), 4694 _claim(claim) { 4695 4696 } 4697 4698 void do_cld(ClassLoaderData* cld) { 4699 cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim); 4700 } 4701 }; 4702 4703 void work(uint worker_id) { 4704 if (worker_id >= _n_workers) return; // no work needed this round 4705 4706 double start_time_ms = os::elapsedTime() * 1000.0; 4707 _g1h->g1_policy()->phase_times()->record_gc_worker_start_time(worker_id, start_time_ms); 4708 4709 { 4710 ResourceMark rm; 4711 HandleMark hm; 4712 4713 ReferenceProcessor* rp = _g1h->ref_processor_stw(); 4714 4715 G1ParScanThreadState pss(_g1h, worker_id, rp); 4716 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp); 4717 4718 pss.set_evac_failure_closure(&evac_failure_cl); 4719 4720 bool only_young = _g1h->g1_policy()->gcs_are_young(); 4721 4722 // Non-IM young GC. 4723 G1ParCopyClosure<G1BarrierNone, G1MarkNone> scan_only_root_cl(_g1h, &pss, rp); 4724 G1CLDClosure<G1MarkNone> scan_only_cld_cl(&scan_only_root_cl, 4725 only_young, // Only process dirty klasses. 4726 false); // No need to claim CLDs. 4727 // IM young GC. 4728 // Strong roots closures. 4729 G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot> scan_mark_root_cl(_g1h, &pss, rp); 4730 G1CLDClosure<G1MarkFromRoot> scan_mark_cld_cl(&scan_mark_root_cl, 4731 false, // Process all klasses. 4732 true); // Need to claim CLDs. 4733 // Weak roots closures. 4734 G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, &pss, rp); 4735 G1CLDClosure<G1MarkPromotedFromRoot> scan_mark_weak_cld_cl(&scan_mark_weak_root_cl, 4736 false, // Process all klasses. 4737 true); // Need to claim CLDs. 4738 4739 G1CodeBlobClosure scan_only_code_cl(&scan_only_root_cl); 4740 G1CodeBlobClosure scan_mark_code_cl(&scan_mark_root_cl); 4741 // IM Weak code roots are handled later. 4742 4743 OopClosure* strong_root_cl; 4744 OopClosure* weak_root_cl; 4745 CLDClosure* strong_cld_cl; 4746 CLDClosure* weak_cld_cl; 4747 CodeBlobClosure* strong_code_cl; 4748 4749 if (_g1h->g1_policy()->during_initial_mark_pause()) { 4750 // We also need to mark copied objects. 4751 strong_root_cl = &scan_mark_root_cl; 4752 strong_cld_cl = &scan_mark_cld_cl; 4753 strong_code_cl = &scan_mark_code_cl; 4754 if (ClassUnloadingWithConcurrentMark) { 4755 weak_root_cl = &scan_mark_weak_root_cl; 4756 weak_cld_cl = &scan_mark_weak_cld_cl; 4757 } else { 4758 weak_root_cl = &scan_mark_root_cl; 4759 weak_cld_cl = &scan_mark_cld_cl; 4760 } 4761 } else { 4762 strong_root_cl = &scan_only_root_cl; 4763 weak_root_cl = &scan_only_root_cl; 4764 strong_cld_cl = &scan_only_cld_cl; 4765 weak_cld_cl = &scan_only_cld_cl; 4766 strong_code_cl = &scan_only_code_cl; 4767 } 4768 4769 4770 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss); 4771 4772 pss.start_strong_roots(); 4773 _g1h->g1_process_roots(strong_root_cl, 4774 weak_root_cl, 4775 &push_heap_rs_cl, 4776 strong_cld_cl, 4777 weak_cld_cl, 4778 strong_code_cl, 4779 worker_id); 4780 4781 pss.end_strong_roots(); 4782 4783 { 4784 double start = os::elapsedTime(); 4785 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator); 4786 evac.do_void(); 4787 double elapsed_ms = (os::elapsedTime()-start)*1000.0; 4788 double term_ms = pss.term_time()*1000.0; 4789 _g1h->g1_policy()->phase_times()->add_obj_copy_time(worker_id, elapsed_ms-term_ms); 4790 _g1h->g1_policy()->phase_times()->record_termination(worker_id, term_ms, pss.term_attempts()); 4791 } 4792 _g1h->g1_policy()->record_thread_age_table(pss.age_table()); 4793 _g1h->update_surviving_young_words(pss.surviving_young_words()+1); 4794 4795 if (ParallelGCVerbose) { 4796 MutexLocker x(stats_lock()); 4797 pss.print_termination_stats(worker_id); 4798 } 4799 4800 assert(pss.queue_is_empty(), "should be empty"); 4801 4802 // Close the inner scope so that the ResourceMark and HandleMark 4803 // destructors are executed here and are included as part of the 4804 // "GC Worker Time". 4805 } 4806 4807 double end_time_ms = os::elapsedTime() * 1000.0; 4808 _g1h->g1_policy()->phase_times()->record_gc_worker_end_time(worker_id, end_time_ms); 4809 } 4810 }; 4811 4812 // *** Common G1 Evacuation Stuff 4813 4814 // This method is run in a GC worker. 4815 4816 void 4817 G1CollectedHeap:: 4818 g1_process_roots(OopClosure* scan_non_heap_roots, 4819 OopClosure* scan_non_heap_weak_roots, 4820 OopsInHeapRegionClosure* scan_rs, 4821 CLDClosure* scan_strong_clds, 4822 CLDClosure* scan_weak_clds, 4823 CodeBlobClosure* scan_strong_code, 4824 uint worker_i) { 4825 4826 // First scan the shared roots. 4827 double ext_roots_start = os::elapsedTime(); 4828 double closure_app_time_sec = 0.0; 4829 4830 bool during_im = _g1h->g1_policy()->during_initial_mark_pause(); 4831 bool trace_metadata = during_im && ClassUnloadingWithConcurrentMark; 4832 4833 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots); 4834 BufferingOopClosure buf_scan_non_heap_weak_roots(scan_non_heap_weak_roots); 4835 4836 process_roots(false, // no scoping; this is parallel code 4837 SharedHeap::SO_None, 4838 &buf_scan_non_heap_roots, 4839 &buf_scan_non_heap_weak_roots, 4840 scan_strong_clds, 4841 // Unloading Initial Marks handle the weak CLDs separately. 4842 (trace_metadata ? NULL : scan_weak_clds), 4843 scan_strong_code); 4844 4845 // Now the CM ref_processor roots. 4846 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) { 4847 // We need to treat the discovered reference lists of the 4848 // concurrent mark ref processor as roots and keep entries 4849 // (which are added by the marking threads) on them live 4850 // until they can be processed at the end of marking. 4851 ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots); 4852 } 4853 4854 if (trace_metadata) { 4855 // Barrier to make sure all workers passed 4856 // the strong CLD and strong nmethods phases. 4857 active_strong_roots_scope()->wait_until_all_workers_done_with_threads(n_par_threads()); 4858 4859 // Now take the complement of the strong CLDs. 4860 ClassLoaderDataGraph::roots_cld_do(NULL, scan_weak_clds); 4861 } 4862 4863 // Finish up any enqueued closure apps (attributed as object copy time). 4864 buf_scan_non_heap_roots.done(); 4865 buf_scan_non_heap_weak_roots.done(); 4866 4867 double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds() 4868 + buf_scan_non_heap_weak_roots.closure_app_seconds(); 4869 4870 g1_policy()->phase_times()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0); 4871 4872 double ext_root_time_ms = 4873 ((os::elapsedTime() - ext_roots_start) - obj_copy_time_sec) * 1000.0; 4874 4875 g1_policy()->phase_times()->record_ext_root_scan_time(worker_i, ext_root_time_ms); 4876 4877 // During conc marking we have to filter the per-thread SATB buffers 4878 // to make sure we remove any oops into the CSet (which will show up 4879 // as implicitly live). 4880 double satb_filtering_ms = 0.0; 4881 if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers)) { 4882 if (mark_in_progress()) { 4883 double satb_filter_start = os::elapsedTime(); 4884 4885 JavaThread::satb_mark_queue_set().filter_thread_buffers(); 4886 4887 satb_filtering_ms = (os::elapsedTime() - satb_filter_start) * 1000.0; 4888 } 4889 } 4890 g1_policy()->phase_times()->record_satb_filtering_time(worker_i, satb_filtering_ms); 4891 4892 // Now scan the complement of the collection set. 4893 G1CodeBlobClosure scavenge_cs_nmethods(scan_non_heap_weak_roots); 4894 4895 g1_rem_set()->oops_into_collection_set_do(scan_rs, &scavenge_cs_nmethods, worker_i); 4896 4897 _process_strong_tasks->all_tasks_completed(); 4898 } 4899 4900 class G1StringSymbolTableUnlinkTask : public AbstractGangTask { 4901 private: 4902 BoolObjectClosure* _is_alive; 4903 int _initial_string_table_size; 4904 int _initial_symbol_table_size; 4905 4906 bool _process_strings; 4907 int _strings_processed; 4908 int _strings_removed; 4909 4910 bool _process_symbols; 4911 int _symbols_processed; 4912 int _symbols_removed; 4913 4914 bool _do_in_parallel; 4915 public: 4916 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) : 4917 AbstractGangTask("String/Symbol Unlinking"), 4918 _is_alive(is_alive), 4919 _do_in_parallel(G1CollectedHeap::use_parallel_gc_threads()), 4920 _process_strings(process_strings), _strings_processed(0), _strings_removed(0), 4921 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) { 4922 4923 _initial_string_table_size = StringTable::the_table()->table_size(); 4924 _initial_symbol_table_size = SymbolTable::the_table()->table_size(); 4925 if (process_strings) { 4926 StringTable::clear_parallel_claimed_index(); 4927 } 4928 if (process_symbols) { 4929 SymbolTable::clear_parallel_claimed_index(); 4930 } 4931 } 4932 4933 ~G1StringSymbolTableUnlinkTask() { 4934 guarantee(!_process_strings || !_do_in_parallel || StringTable::parallel_claimed_index() >= _initial_string_table_size, 4935 err_msg("claim value "INT32_FORMAT" after unlink less than initial string table size "INT32_FORMAT, 4936 StringTable::parallel_claimed_index(), _initial_string_table_size)); 4937 guarantee(!_process_symbols || !_do_in_parallel || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size, 4938 err_msg("claim value "INT32_FORMAT" after unlink less than initial symbol table size "INT32_FORMAT, 4939 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size)); 4940 4941 if (G1TraceStringSymbolTableScrubbing) { 4942 gclog_or_tty->print_cr("Cleaned string and symbol table, " 4943 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, " 4944 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed", 4945 strings_processed(), strings_removed(), 4946 symbols_processed(), symbols_removed()); 4947 } 4948 } 4949 4950 void work(uint worker_id) { 4951 if (_do_in_parallel) { 4952 int strings_processed = 0; 4953 int strings_removed = 0; 4954 int symbols_processed = 0; 4955 int symbols_removed = 0; 4956 if (_process_strings) { 4957 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed); 4958 Atomic::add(strings_processed, &_strings_processed); 4959 Atomic::add(strings_removed, &_strings_removed); 4960 } 4961 if (_process_symbols) { 4962 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed); 4963 Atomic::add(symbols_processed, &_symbols_processed); 4964 Atomic::add(symbols_removed, &_symbols_removed); 4965 } 4966 } else { 4967 if (_process_strings) { 4968 StringTable::unlink(_is_alive, &_strings_processed, &_strings_removed); 4969 } 4970 if (_process_symbols) { 4971 SymbolTable::unlink(&_symbols_processed, &_symbols_removed); 4972 } 4973 } 4974 } 4975 4976 size_t strings_processed() const { return (size_t)_strings_processed; } 4977 size_t strings_removed() const { return (size_t)_strings_removed; } 4978 4979 size_t symbols_processed() const { return (size_t)_symbols_processed; } 4980 size_t symbols_removed() const { return (size_t)_symbols_removed; } 4981 }; 4982 4983 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC { 4984 private: 4985 static Monitor* _lock; 4986 4987 BoolObjectClosure* const _is_alive; 4988 const bool _unloading_occurred; 4989 const uint _num_workers; 4990 4991 // Variables used to claim nmethods. 4992 nmethod* _first_nmethod; 4993 volatile nmethod* _claimed_nmethod; 4994 4995 // The list of nmethods that need to be processed by the second pass. 4996 volatile nmethod* _postponed_list; 4997 volatile uint _num_entered_barrier; 4998 4999 public: 5000 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) : 5001 _is_alive(is_alive), 5002 _unloading_occurred(unloading_occurred), 5003 _num_workers(num_workers), 5004 _first_nmethod(NULL), 5005 _claimed_nmethod(NULL), 5006 _postponed_list(NULL), 5007 _num_entered_barrier(0) 5008 { 5009 nmethod::increase_unloading_clock(); 5010 _first_nmethod = CodeCache::alive_nmethod(CodeCache::first()); 5011 _claimed_nmethod = (volatile nmethod*)_first_nmethod; 5012 } 5013 5014 ~G1CodeCacheUnloadingTask() { 5015 CodeCache::verify_clean_inline_caches(); 5016 5017 CodeCache::set_needs_cache_clean(false); 5018 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be"); 5019 5020 CodeCache::verify_icholder_relocations(); 5021 } 5022 5023 private: 5024 void add_to_postponed_list(nmethod* nm) { 5025 nmethod* old; 5026 do { 5027 old = (nmethod*)_postponed_list; 5028 nm->set_unloading_next(old); 5029 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old); 5030 } 5031 5032 void clean_nmethod(nmethod* nm) { 5033 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred); 5034 5035 if (postponed) { 5036 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet. 5037 add_to_postponed_list(nm); 5038 } 5039 5040 // Mark that this thread has been cleaned/unloaded. 5041 // After this call, it will be safe to ask if this nmethod was unloaded or not. 5042 nm->set_unloading_clock(nmethod::global_unloading_clock()); 5043 } 5044 5045 void clean_nmethod_postponed(nmethod* nm) { 5046 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred); 5047 } 5048 5049 static const int MaxClaimNmethods = 16; 5050 5051 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) { 5052 nmethod* first; 5053 nmethod* last; 5054 5055 do { 5056 *num_claimed_nmethods = 0; 5057 5058 first = last = (nmethod*)_claimed_nmethod; 5059 5060 if (first != NULL) { 5061 for (int i = 0; i < MaxClaimNmethods; i++) { 5062 last = CodeCache::alive_nmethod(CodeCache::next(last)); 5063 5064 if (last == NULL) { 5065 break; 5066 } 5067 5068 claimed_nmethods[i] = last; 5069 (*num_claimed_nmethods)++; 5070 } 5071 } 5072 5073 } while ((nmethod*)Atomic::cmpxchg_ptr(last, &_claimed_nmethod, first) != first); 5074 } 5075 5076 nmethod* claim_postponed_nmethod() { 5077 nmethod* claim; 5078 nmethod* next; 5079 5080 do { 5081 claim = (nmethod*)_postponed_list; 5082 if (claim == NULL) { 5083 return NULL; 5084 } 5085 5086 next = claim->unloading_next(); 5087 5088 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim); 5089 5090 return claim; 5091 } 5092 5093 public: 5094 // Mark that we're done with the first pass of nmethod cleaning. 5095 void barrier_mark(uint worker_id) { 5096 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 5097 _num_entered_barrier++; 5098 if (_num_entered_barrier == _num_workers) { 5099 ml.notify_all(); 5100 } 5101 } 5102 5103 // See if we have to wait for the other workers to 5104 // finish their first-pass nmethod cleaning work. 5105 void barrier_wait(uint worker_id) { 5106 if (_num_entered_barrier < _num_workers) { 5107 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 5108 while (_num_entered_barrier < _num_workers) { 5109 ml.wait(Mutex::_no_safepoint_check_flag, 0, false); 5110 } 5111 } 5112 } 5113 5114 // Cleaning and unloading of nmethods. Some work has to be postponed 5115 // to the second pass, when we know which nmethods survive. 5116 void work_first_pass(uint worker_id) { 5117 // The first nmethods is claimed by the first worker. 5118 if (worker_id == 0 && _first_nmethod != NULL) { 5119 clean_nmethod(_first_nmethod); 5120 _first_nmethod = NULL; 5121 } 5122 5123 int num_claimed_nmethods; 5124 nmethod* claimed_nmethods[MaxClaimNmethods]; 5125 5126 while (true) { 5127 claim_nmethods(claimed_nmethods, &num_claimed_nmethods); 5128 5129 if (num_claimed_nmethods == 0) { 5130 break; 5131 } 5132 5133 for (int i = 0; i < num_claimed_nmethods; i++) { 5134 clean_nmethod(claimed_nmethods[i]); 5135 } 5136 } 5137 5138 // The nmethod cleaning helps out and does the CodeCache part of MetadataOnStackMark. 5139 // Need to retire the buffers now that this thread has stopped cleaning nmethods. 5140 MetadataOnStackMark::retire_buffer_for_thread(Thread::current()); 5141 } 5142 5143 void work_second_pass(uint worker_id) { 5144 nmethod* nm; 5145 // Take care of postponed nmethods. 5146 while ((nm = claim_postponed_nmethod()) != NULL) { 5147 clean_nmethod_postponed(nm); 5148 } 5149 } 5150 }; 5151 5152 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock"); 5153 5154 class G1KlassCleaningTask : public StackObj { 5155 BoolObjectClosure* _is_alive; 5156 volatile jint _clean_klass_tree_claimed; 5157 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator; 5158 5159 public: 5160 G1KlassCleaningTask(BoolObjectClosure* is_alive) : 5161 _is_alive(is_alive), 5162 _clean_klass_tree_claimed(0), 5163 _klass_iterator() { 5164 } 5165 5166 private: 5167 bool claim_clean_klass_tree_task() { 5168 if (_clean_klass_tree_claimed) { 5169 return false; 5170 } 5171 5172 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0; 5173 } 5174 5175 InstanceKlass* claim_next_klass() { 5176 Klass* klass; 5177 do { 5178 klass =_klass_iterator.next_klass(); 5179 } while (klass != NULL && !klass->oop_is_instance()); 5180 5181 return (InstanceKlass*)klass; 5182 } 5183 5184 public: 5185 5186 void clean_klass(InstanceKlass* ik) { 5187 ik->clean_implementors_list(_is_alive); 5188 ik->clean_method_data(_is_alive); 5189 5190 // G1 specific cleanup work that has 5191 // been moved here to be done in parallel. 5192 ik->clean_dependent_nmethods(); 5193 if (JvmtiExport::has_redefined_a_class()) { 5194 InstanceKlass::purge_previous_versions(ik); 5195 } 5196 } 5197 5198 void work() { 5199 ResourceMark rm; 5200 5201 // One worker will clean the subklass/sibling klass tree. 5202 if (claim_clean_klass_tree_task()) { 5203 Klass::clean_subklass_tree(_is_alive); 5204 } 5205 5206 // All workers will help cleaning the classes, 5207 InstanceKlass* klass; 5208 while ((klass = claim_next_klass()) != NULL) { 5209 clean_klass(klass); 5210 } 5211 } 5212 }; 5213 5214 // To minimize the remark pause times, the tasks below are done in parallel. 5215 class G1ParallelCleaningTask : public AbstractGangTask { 5216 private: 5217 G1StringSymbolTableUnlinkTask _string_symbol_task; 5218 G1CodeCacheUnloadingTask _code_cache_task; 5219 G1KlassCleaningTask _klass_cleaning_task; 5220 5221 public: 5222 // The constructor is run in the VMThread. 5223 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) : 5224 AbstractGangTask("Parallel Cleaning"), 5225 _string_symbol_task(is_alive, process_strings, process_symbols), 5226 _code_cache_task(num_workers, is_alive, unloading_occurred), 5227 _klass_cleaning_task(is_alive) { 5228 } 5229 5230 void pre_work_verification() { 5231 assert(!MetadataOnStackMark::has_buffer_for_thread(Thread::current()), "Should be empty"); 5232 } 5233 5234 void post_work_verification() { 5235 assert(!MetadataOnStackMark::has_buffer_for_thread(Thread::current()), "Should be empty"); 5236 } 5237 5238 // The parallel work done by all worker threads. 5239 void work(uint worker_id) { 5240 pre_work_verification(); 5241 5242 // Do first pass of code cache cleaning. 5243 _code_cache_task.work_first_pass(worker_id); 5244 5245 // Let the threads mark that the first pass is done. 5246 _code_cache_task.barrier_mark(worker_id); 5247 5248 // Clean the Strings and Symbols. 5249 _string_symbol_task.work(worker_id); 5250 5251 // Wait for all workers to finish the first code cache cleaning pass. 5252 _code_cache_task.barrier_wait(worker_id); 5253 5254 // Do the second code cache cleaning work, which realize on 5255 // the liveness information gathered during the first pass. 5256 _code_cache_task.work_second_pass(worker_id); 5257 5258 // Clean all klasses that were not unloaded. 5259 _klass_cleaning_task.work(); 5260 5261 post_work_verification(); 5262 } 5263 }; 5264 5265 5266 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive, 5267 bool process_strings, 5268 bool process_symbols, 5269 bool class_unloading_occurred) { 5270 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ? 5271 workers()->active_workers() : 1); 5272 5273 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, 5274 n_workers, class_unloading_occurred); 5275 if (G1CollectedHeap::use_parallel_gc_threads()) { 5276 set_par_threads(n_workers); 5277 workers()->run_task(&g1_unlink_task); 5278 set_par_threads(0); 5279 } else { 5280 g1_unlink_task.work(0); 5281 } 5282 } 5283 5284 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive, 5285 bool process_strings, bool process_symbols) { 5286 { 5287 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ? 5288 _g1h->workers()->active_workers() : 1); 5289 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols); 5290 if (G1CollectedHeap::use_parallel_gc_threads()) { 5291 set_par_threads(n_workers); 5292 workers()->run_task(&g1_unlink_task); 5293 set_par_threads(0); 5294 } else { 5295 g1_unlink_task.work(0); 5296 } 5297 } 5298 5299 if (G1StringDedup::is_enabled()) { 5300 G1StringDedup::unlink(is_alive); 5301 } 5302 } 5303 5304 class G1RedirtyLoggedCardsTask : public AbstractGangTask { 5305 private: 5306 DirtyCardQueueSet* _queue; 5307 public: 5308 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { } 5309 5310 virtual void work(uint worker_id) { 5311 double start_time = os::elapsedTime(); 5312 5313 RedirtyLoggedCardTableEntryClosure cl; 5314 if (G1CollectedHeap::heap()->use_parallel_gc_threads()) { 5315 _queue->par_apply_closure_to_all_completed_buffers(&cl); 5316 } else { 5317 _queue->apply_closure_to_all_completed_buffers(&cl); 5318 } 5319 5320 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times(); 5321 timer->record_redirty_logged_cards_time_ms(worker_id, (os::elapsedTime() - start_time) * 1000.0); 5322 timer->record_redirty_logged_cards_processed_cards(worker_id, cl.num_processed()); 5323 } 5324 }; 5325 5326 void G1CollectedHeap::redirty_logged_cards() { 5327 double redirty_logged_cards_start = os::elapsedTime(); 5328 5329 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ? 5330 _g1h->workers()->active_workers() : 1); 5331 5332 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set()); 5333 dirty_card_queue_set().reset_for_par_iteration(); 5334 if (use_parallel_gc_threads()) { 5335 set_par_threads(n_workers); 5336 workers()->run_task(&redirty_task); 5337 set_par_threads(0); 5338 } else { 5339 redirty_task.work(0); 5340 } 5341 5342 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set(); 5343 dcq.merge_bufferlists(&dirty_card_queue_set()); 5344 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed"); 5345 5346 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0); 5347 } 5348 5349 // Weak Reference Processing support 5350 5351 // An always "is_alive" closure that is used to preserve referents. 5352 // If the object is non-null then it's alive. Used in the preservation 5353 // of referent objects that are pointed to by reference objects 5354 // discovered by the CM ref processor. 5355 class G1AlwaysAliveClosure: public BoolObjectClosure { 5356 G1CollectedHeap* _g1; 5357 public: 5358 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 5359 bool do_object_b(oop p) { 5360 if (p != NULL) { 5361 return true; 5362 } 5363 return false; 5364 } 5365 }; 5366 5367 bool G1STWIsAliveClosure::do_object_b(oop p) { 5368 // An object is reachable if it is outside the collection set, 5369 // or is inside and copied. 5370 return !_g1->obj_in_cs(p) || p->is_forwarded(); 5371 } 5372 5373 // Non Copying Keep Alive closure 5374 class G1KeepAliveClosure: public OopClosure { 5375 G1CollectedHeap* _g1; 5376 public: 5377 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 5378 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } 5379 void do_oop(oop* p) { 5380 oop obj = *p; 5381 assert(obj != NULL, "the caller should have filtered out NULL values"); 5382 5383 G1CollectedHeap::in_cset_state_t cset_state = _g1->in_cset_state(obj); 5384 if (cset_state == G1CollectedHeap::InNeither) { 5385 return; 5386 } 5387 if (cset_state == G1CollectedHeap::InCSet) { 5388 assert( obj->is_forwarded(), "invariant" ); 5389 *p = obj->forwardee(); 5390 } else { 5391 assert(!obj->is_forwarded(), "invariant" ); 5392 assert(cset_state == G1CollectedHeap::IsHumongous, 5393 err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state)); 5394 _g1->set_humongous_is_live(obj); 5395 } 5396 } 5397 }; 5398 5399 // Copying Keep Alive closure - can be called from both 5400 // serial and parallel code as long as different worker 5401 // threads utilize different G1ParScanThreadState instances 5402 // and different queues. 5403 5404 class G1CopyingKeepAliveClosure: public OopClosure { 5405 G1CollectedHeap* _g1h; 5406 OopClosure* _copy_non_heap_obj_cl; 5407 G1ParScanThreadState* _par_scan_state; 5408 5409 public: 5410 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, 5411 OopClosure* non_heap_obj_cl, 5412 G1ParScanThreadState* pss): 5413 _g1h(g1h), 5414 _copy_non_heap_obj_cl(non_heap_obj_cl), 5415 _par_scan_state(pss) 5416 {} 5417 5418 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 5419 virtual void do_oop( oop* p) { do_oop_work(p); } 5420 5421 template <class T> void do_oop_work(T* p) { 5422 oop obj = oopDesc::load_decode_heap_oop(p); 5423 5424 if (_g1h->is_in_cset_or_humongous(obj)) { 5425 // If the referent object has been forwarded (either copied 5426 // to a new location or to itself in the event of an 5427 // evacuation failure) then we need to update the reference 5428 // field and, if both reference and referent are in the G1 5429 // heap, update the RSet for the referent. 5430 // 5431 // If the referent has not been forwarded then we have to keep 5432 // it alive by policy. Therefore we have copy the referent. 5433 // 5434 // If the reference field is in the G1 heap then we can push 5435 // on the PSS queue. When the queue is drained (after each 5436 // phase of reference processing) the object and it's followers 5437 // will be copied, the reference field set to point to the 5438 // new location, and the RSet updated. Otherwise we need to 5439 // use the the non-heap or metadata closures directly to copy 5440 // the referent object and update the pointer, while avoiding 5441 // updating the RSet. 5442 5443 if (_g1h->is_in_g1_reserved(p)) { 5444 _par_scan_state->push_on_queue(p); 5445 } else { 5446 assert(!Metaspace::contains((const void*)p), 5447 err_msg("Unexpectedly found a pointer from metadata: " 5448 PTR_FORMAT, p)); 5449 _copy_non_heap_obj_cl->do_oop(p); 5450 } 5451 } 5452 } 5453 }; 5454 5455 // Serial drain queue closure. Called as the 'complete_gc' 5456 // closure for each discovered list in some of the 5457 // reference processing phases. 5458 5459 class G1STWDrainQueueClosure: public VoidClosure { 5460 protected: 5461 G1CollectedHeap* _g1h; 5462 G1ParScanThreadState* _par_scan_state; 5463 5464 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 5465 5466 public: 5467 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : 5468 _g1h(g1h), 5469 _par_scan_state(pss) 5470 { } 5471 5472 void do_void() { 5473 G1ParScanThreadState* const pss = par_scan_state(); 5474 pss->trim_queue(); 5475 } 5476 }; 5477 5478 // Parallel Reference Processing closures 5479 5480 // Implementation of AbstractRefProcTaskExecutor for parallel reference 5481 // processing during G1 evacuation pauses. 5482 5483 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 5484 private: 5485 G1CollectedHeap* _g1h; 5486 RefToScanQueueSet* _queues; 5487 FlexibleWorkGang* _workers; 5488 int _active_workers; 5489 5490 public: 5491 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, 5492 FlexibleWorkGang* workers, 5493 RefToScanQueueSet *task_queues, 5494 int n_workers) : 5495 _g1h(g1h), 5496 _queues(task_queues), 5497 _workers(workers), 5498 _active_workers(n_workers) 5499 { 5500 assert(n_workers > 0, "shouldn't call this otherwise"); 5501 } 5502 5503 // Executes the given task using concurrent marking worker threads. 5504 virtual void execute(ProcessTask& task); 5505 virtual void execute(EnqueueTask& task); 5506 }; 5507 5508 // Gang task for possibly parallel reference processing 5509 5510 class G1STWRefProcTaskProxy: public AbstractGangTask { 5511 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 5512 ProcessTask& _proc_task; 5513 G1CollectedHeap* _g1h; 5514 RefToScanQueueSet *_task_queues; 5515 ParallelTaskTerminator* _terminator; 5516 5517 public: 5518 G1STWRefProcTaskProxy(ProcessTask& proc_task, 5519 G1CollectedHeap* g1h, 5520 RefToScanQueueSet *task_queues, 5521 ParallelTaskTerminator* terminator) : 5522 AbstractGangTask("Process reference objects in parallel"), 5523 _proc_task(proc_task), 5524 _g1h(g1h), 5525 _task_queues(task_queues), 5526 _terminator(terminator) 5527 {} 5528 5529 virtual void work(uint worker_id) { 5530 // The reference processing task executed by a single worker. 5531 ResourceMark rm; 5532 HandleMark hm; 5533 5534 G1STWIsAliveClosure is_alive(_g1h); 5535 5536 G1ParScanThreadState pss(_g1h, worker_id, NULL); 5537 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL); 5538 5539 pss.set_evac_failure_closure(&evac_failure_cl); 5540 5541 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL); 5542 5543 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL); 5544 5545 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5546 5547 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5548 // We also need to mark copied objects. 5549 copy_non_heap_cl = ©_mark_non_heap_cl; 5550 } 5551 5552 // Keep alive closure. 5553 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss); 5554 5555 // Complete GC closure 5556 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator); 5557 5558 // Call the reference processing task's work routine. 5559 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); 5560 5561 // Note we cannot assert that the refs array is empty here as not all 5562 // of the processing tasks (specifically phase2 - pp2_work) execute 5563 // the complete_gc closure (which ordinarily would drain the queue) so 5564 // the queue may not be empty. 5565 } 5566 }; 5567 5568 // Driver routine for parallel reference processing. 5569 // Creates an instance of the ref processing gang 5570 // task and has the worker threads execute it. 5571 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) { 5572 assert(_workers != NULL, "Need parallel worker threads."); 5573 5574 ParallelTaskTerminator terminator(_active_workers, _queues); 5575 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator); 5576 5577 _g1h->set_par_threads(_active_workers); 5578 _workers->run_task(&proc_task_proxy); 5579 _g1h->set_par_threads(0); 5580 } 5581 5582 // Gang task for parallel reference enqueueing. 5583 5584 class G1STWRefEnqueueTaskProxy: public AbstractGangTask { 5585 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; 5586 EnqueueTask& _enq_task; 5587 5588 public: 5589 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) : 5590 AbstractGangTask("Enqueue reference objects in parallel"), 5591 _enq_task(enq_task) 5592 { } 5593 5594 virtual void work(uint worker_id) { 5595 _enq_task.work(worker_id); 5596 } 5597 }; 5598 5599 // Driver routine for parallel reference enqueueing. 5600 // Creates an instance of the ref enqueueing gang 5601 // task and has the worker threads execute it. 5602 5603 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) { 5604 assert(_workers != NULL, "Need parallel worker threads."); 5605 5606 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task); 5607 5608 _g1h->set_par_threads(_active_workers); 5609 _workers->run_task(&enq_task_proxy); 5610 _g1h->set_par_threads(0); 5611 } 5612 5613 // End of weak reference support closures 5614 5615 // Abstract task used to preserve (i.e. copy) any referent objects 5616 // that are in the collection set and are pointed to by reference 5617 // objects discovered by the CM ref processor. 5618 5619 class G1ParPreserveCMReferentsTask: public AbstractGangTask { 5620 protected: 5621 G1CollectedHeap* _g1h; 5622 RefToScanQueueSet *_queues; 5623 ParallelTaskTerminator _terminator; 5624 uint _n_workers; 5625 5626 public: 5627 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) : 5628 AbstractGangTask("ParPreserveCMReferents"), 5629 _g1h(g1h), 5630 _queues(task_queues), 5631 _terminator(workers, _queues), 5632 _n_workers(workers) 5633 { } 5634 5635 void work(uint worker_id) { 5636 ResourceMark rm; 5637 HandleMark hm; 5638 5639 G1ParScanThreadState pss(_g1h, worker_id, NULL); 5640 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL); 5641 5642 pss.set_evac_failure_closure(&evac_failure_cl); 5643 5644 assert(pss.queue_is_empty(), "both queue and overflow should be empty"); 5645 5646 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL); 5647 5648 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL); 5649 5650 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5651 5652 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5653 // We also need to mark copied objects. 5654 copy_non_heap_cl = ©_mark_non_heap_cl; 5655 } 5656 5657 // Is alive closure 5658 G1AlwaysAliveClosure always_alive(_g1h); 5659 5660 // Copying keep alive closure. Applied to referent objects that need 5661 // to be copied. 5662 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss); 5663 5664 ReferenceProcessor* rp = _g1h->ref_processor_cm(); 5665 5666 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q(); 5667 uint stride = MIN2(MAX2(_n_workers, 1U), limit); 5668 5669 // limit is set using max_num_q() - which was set using ParallelGCThreads. 5670 // So this must be true - but assert just in case someone decides to 5671 // change the worker ids. 5672 assert(0 <= worker_id && worker_id < limit, "sanity"); 5673 assert(!rp->discovery_is_atomic(), "check this code"); 5674 5675 // Select discovered lists [i, i+stride, i+2*stride,...,limit) 5676 for (uint idx = worker_id; idx < limit; idx += stride) { 5677 DiscoveredList& ref_list = rp->discovered_refs()[idx]; 5678 5679 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive); 5680 while (iter.has_next()) { 5681 // Since discovery is not atomic for the CM ref processor, we 5682 // can see some null referent objects. 5683 iter.load_ptrs(DEBUG_ONLY(true)); 5684 oop ref = iter.obj(); 5685 5686 // This will filter nulls. 5687 if (iter.is_referent_alive()) { 5688 iter.make_referent_alive(); 5689 } 5690 iter.move_to_next(); 5691 } 5692 } 5693 5694 // Drain the queue - which may cause stealing 5695 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator); 5696 drain_queue.do_void(); 5697 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure 5698 assert(pss.queue_is_empty(), "should be"); 5699 } 5700 }; 5701 5702 // Weak Reference processing during an evacuation pause (part 1). 5703 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) { 5704 double ref_proc_start = os::elapsedTime(); 5705 5706 ReferenceProcessor* rp = _ref_processor_stw; 5707 assert(rp->discovery_enabled(), "should have been enabled"); 5708 5709 // Any reference objects, in the collection set, that were 'discovered' 5710 // by the CM ref processor should have already been copied (either by 5711 // applying the external root copy closure to the discovered lists, or 5712 // by following an RSet entry). 5713 // 5714 // But some of the referents, that are in the collection set, that these 5715 // reference objects point to may not have been copied: the STW ref 5716 // processor would have seen that the reference object had already 5717 // been 'discovered' and would have skipped discovering the reference, 5718 // but would not have treated the reference object as a regular oop. 5719 // As a result the copy closure would not have been applied to the 5720 // referent object. 5721 // 5722 // We need to explicitly copy these referent objects - the references 5723 // will be processed at the end of remarking. 5724 // 5725 // We also need to do this copying before we process the reference 5726 // objects discovered by the STW ref processor in case one of these 5727 // referents points to another object which is also referenced by an 5728 // object discovered by the STW ref processor. 5729 5730 assert(!G1CollectedHeap::use_parallel_gc_threads() || 5731 no_of_gc_workers == workers()->active_workers(), 5732 "Need to reset active GC workers"); 5733 5734 set_par_threads(no_of_gc_workers); 5735 G1ParPreserveCMReferentsTask keep_cm_referents(this, 5736 no_of_gc_workers, 5737 _task_queues); 5738 5739 if (G1CollectedHeap::use_parallel_gc_threads()) { 5740 workers()->run_task(&keep_cm_referents); 5741 } else { 5742 keep_cm_referents.work(0); 5743 } 5744 5745 set_par_threads(0); 5746 5747 // Closure to test whether a referent is alive. 5748 G1STWIsAliveClosure is_alive(this); 5749 5750 // Even when parallel reference processing is enabled, the processing 5751 // of JNI refs is serial and performed serially by the current thread 5752 // rather than by a worker. The following PSS will be used for processing 5753 // JNI refs. 5754 5755 // Use only a single queue for this PSS. 5756 G1ParScanThreadState pss(this, 0, NULL); 5757 5758 // We do not embed a reference processor in the copying/scanning 5759 // closures while we're actually processing the discovered 5760 // reference objects. 5761 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL); 5762 5763 pss.set_evac_failure_closure(&evac_failure_cl); 5764 5765 assert(pss.queue_is_empty(), "pre-condition"); 5766 5767 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL); 5768 5769 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL); 5770 5771 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5772 5773 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5774 // We also need to mark copied objects. 5775 copy_non_heap_cl = ©_mark_non_heap_cl; 5776 } 5777 5778 // Keep alive closure. 5779 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, &pss); 5780 5781 // Serial Complete GC closure 5782 G1STWDrainQueueClosure drain_queue(this, &pss); 5783 5784 // Setup the soft refs policy... 5785 rp->setup_policy(false); 5786 5787 ReferenceProcessorStats stats; 5788 if (!rp->processing_is_mt()) { 5789 // Serial reference processing... 5790 stats = rp->process_discovered_references(&is_alive, 5791 &keep_alive, 5792 &drain_queue, 5793 NULL, 5794 _gc_timer_stw, 5795 _gc_tracer_stw->gc_id()); 5796 } else { 5797 // Parallel reference processing 5798 assert(rp->num_q() == no_of_gc_workers, "sanity"); 5799 assert(no_of_gc_workers <= rp->max_num_q(), "sanity"); 5800 5801 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers); 5802 stats = rp->process_discovered_references(&is_alive, 5803 &keep_alive, 5804 &drain_queue, 5805 &par_task_executor, 5806 _gc_timer_stw, 5807 _gc_tracer_stw->gc_id()); 5808 } 5809 5810 _gc_tracer_stw->report_gc_reference_stats(stats); 5811 5812 // We have completed copying any necessary live referent objects. 5813 assert(pss.queue_is_empty(), "both queue and overflow should be empty"); 5814 5815 double ref_proc_time = os::elapsedTime() - ref_proc_start; 5816 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 5817 } 5818 5819 // Weak Reference processing during an evacuation pause (part 2). 5820 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) { 5821 double ref_enq_start = os::elapsedTime(); 5822 5823 ReferenceProcessor* rp = _ref_processor_stw; 5824 assert(!rp->discovery_enabled(), "should have been disabled as part of processing"); 5825 5826 // Now enqueue any remaining on the discovered lists on to 5827 // the pending list. 5828 if (!rp->processing_is_mt()) { 5829 // Serial reference processing... 5830 rp->enqueue_discovered_references(); 5831 } else { 5832 // Parallel reference enqueueing 5833 5834 assert(no_of_gc_workers == workers()->active_workers(), 5835 "Need to reset active workers"); 5836 assert(rp->num_q() == no_of_gc_workers, "sanity"); 5837 assert(no_of_gc_workers <= rp->max_num_q(), "sanity"); 5838 5839 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers); 5840 rp->enqueue_discovered_references(&par_task_executor); 5841 } 5842 5843 rp->verify_no_references_recorded(); 5844 assert(!rp->discovery_enabled(), "should have been disabled"); 5845 5846 // FIXME 5847 // CM's reference processing also cleans up the string and symbol tables. 5848 // Should we do that here also? We could, but it is a serial operation 5849 // and could significantly increase the pause time. 5850 5851 double ref_enq_time = os::elapsedTime() - ref_enq_start; 5852 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0); 5853 } 5854 5855 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) { 5856 _expand_heap_after_alloc_failure = true; 5857 _evacuation_failed = false; 5858 5859 // Should G1EvacuationFailureALot be in effect for this GC? 5860 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) 5861 5862 g1_rem_set()->prepare_for_oops_into_collection_set_do(); 5863 5864 // Disable the hot card cache. 5865 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 5866 hot_card_cache->reset_hot_cache_claimed_index(); 5867 hot_card_cache->set_use_cache(false); 5868 5869 uint n_workers; 5870 if (G1CollectedHeap::use_parallel_gc_threads()) { 5871 n_workers = 5872 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 5873 workers()->active_workers(), 5874 Threads::number_of_non_daemon_threads()); 5875 assert(UseDynamicNumberOfGCThreads || 5876 n_workers == workers()->total_workers(), 5877 "If not dynamic should be using all the workers"); 5878 workers()->set_active_workers(n_workers); 5879 set_par_threads(n_workers); 5880 } else { 5881 assert(n_par_threads() == 0, 5882 "Should be the original non-parallel value"); 5883 n_workers = 1; 5884 } 5885 5886 G1ParTask g1_par_task(this, _task_queues); 5887 5888 init_for_evac_failure(NULL); 5889 5890 rem_set()->prepare_for_younger_refs_iterate(true); 5891 5892 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty"); 5893 double start_par_time_sec = os::elapsedTime(); 5894 double end_par_time_sec; 5895 5896 { 5897 StrongRootsScope srs(this); 5898 // InitialMark needs claim bits to keep track of the marked-through CLDs. 5899 if (g1_policy()->during_initial_mark_pause()) { 5900 ClassLoaderDataGraph::clear_claimed_marks(); 5901 } 5902 5903 if (G1CollectedHeap::use_parallel_gc_threads()) { 5904 // The individual threads will set their evac-failure closures. 5905 if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr(); 5906 // These tasks use ShareHeap::_process_strong_tasks 5907 assert(UseDynamicNumberOfGCThreads || 5908 workers()->active_workers() == workers()->total_workers(), 5909 "If not dynamic should be using all the workers"); 5910 workers()->run_task(&g1_par_task); 5911 } else { 5912 g1_par_task.set_for_termination(n_workers); 5913 g1_par_task.work(0); 5914 } 5915 end_par_time_sec = os::elapsedTime(); 5916 5917 // Closing the inner scope will execute the destructor 5918 // for the StrongRootsScope object. We record the current 5919 // elapsed time before closing the scope so that time 5920 // taken for the SRS destructor is NOT included in the 5921 // reported parallel time. 5922 } 5923 5924 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0; 5925 g1_policy()->phase_times()->record_par_time(par_time_ms); 5926 5927 double code_root_fixup_time_ms = 5928 (os::elapsedTime() - end_par_time_sec) * 1000.0; 5929 g1_policy()->phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms); 5930 5931 set_par_threads(0); 5932 5933 // Process any discovered reference objects - we have 5934 // to do this _before_ we retire the GC alloc regions 5935 // as we may have to copy some 'reachable' referent 5936 // objects (and their reachable sub-graphs) that were 5937 // not copied during the pause. 5938 process_discovered_references(n_workers); 5939 5940 // Weak root processing. 5941 { 5942 G1STWIsAliveClosure is_alive(this); 5943 G1KeepAliveClosure keep_alive(this); 5944 JNIHandles::weak_oops_do(&is_alive, &keep_alive); 5945 if (G1StringDedup::is_enabled()) { 5946 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive); 5947 } 5948 } 5949 5950 _allocator->release_gc_alloc_regions(n_workers, evacuation_info); 5951 g1_rem_set()->cleanup_after_oops_into_collection_set_do(); 5952 5953 // Reset and re-enable the hot card cache. 5954 // Note the counts for the cards in the regions in the 5955 // collection set are reset when the collection set is freed. 5956 hot_card_cache->reset_hot_cache(); 5957 hot_card_cache->set_use_cache(true); 5958 5959 purge_code_root_memory(); 5960 5961 if (g1_policy()->during_initial_mark_pause()) { 5962 // Reset the claim values set during marking the strong code roots 5963 reset_heap_region_claim_values(); 5964 } 5965 5966 finalize_for_evac_failure(); 5967 5968 if (evacuation_failed()) { 5969 remove_self_forwarding_pointers(); 5970 5971 // Reset the G1EvacuationFailureALot counters and flags 5972 // Note: the values are reset only when an actual 5973 // evacuation failure occurs. 5974 NOT_PRODUCT(reset_evacuation_should_fail();) 5975 } 5976 5977 // Enqueue any remaining references remaining on the STW 5978 // reference processor's discovered lists. We need to do 5979 // this after the card table is cleaned (and verified) as 5980 // the act of enqueueing entries on to the pending list 5981 // will log these updates (and dirty their associated 5982 // cards). We need these updates logged to update any 5983 // RSets. 5984 enqueue_discovered_references(n_workers); 5985 5986 redirty_logged_cards(); 5987 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 5988 } 5989 5990 void G1CollectedHeap::free_region(HeapRegion* hr, 5991 FreeRegionList* free_list, 5992 bool par, 5993 bool locked) { 5994 assert(!hr->is_free(), "the region should not be free"); 5995 assert(!hr->is_empty(), "the region should not be empty"); 5996 assert(_hrm.is_available(hr->hrm_index()), "region should be committed"); 5997 assert(free_list != NULL, "pre-condition"); 5998 5999 if (G1VerifyBitmaps) { 6000 MemRegion mr(hr->bottom(), hr->end()); 6001 concurrent_mark()->clearRangePrevBitmap(mr); 6002 } 6003 6004 // Clear the card counts for this region. 6005 // Note: we only need to do this if the region is not young 6006 // (since we don't refine cards in young regions). 6007 if (!hr->is_young()) { 6008 _cg1r->hot_card_cache()->reset_card_counts(hr); 6009 } 6010 hr->hr_clear(par, true /* clear_space */, locked /* locked */); 6011 free_list->add_ordered(hr); 6012 } 6013 6014 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 6015 FreeRegionList* free_list, 6016 bool par) { 6017 assert(hr->startsHumongous(), "this is only for starts humongous regions"); 6018 assert(free_list != NULL, "pre-condition"); 6019 6020 size_t hr_capacity = hr->capacity(); 6021 // We need to read this before we make the region non-humongous, 6022 // otherwise the information will be gone. 6023 uint last_index = hr->last_hc_index(); 6024 hr->clear_humongous(); 6025 free_region(hr, free_list, par); 6026 6027 uint i = hr->hrm_index() + 1; 6028 while (i < last_index) { 6029 HeapRegion* curr_hr = region_at(i); 6030 assert(curr_hr->continuesHumongous(), "invariant"); 6031 curr_hr->clear_humongous(); 6032 free_region(curr_hr, free_list, par); 6033 i += 1; 6034 } 6035 } 6036 6037 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed, 6038 const HeapRegionSetCount& humongous_regions_removed) { 6039 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) { 6040 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 6041 _old_set.bulk_remove(old_regions_removed); 6042 _humongous_set.bulk_remove(humongous_regions_removed); 6043 } 6044 6045 } 6046 6047 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) { 6048 assert(list != NULL, "list can't be null"); 6049 if (!list->is_empty()) { 6050 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag); 6051 _hrm.insert_list_into_free_list(list); 6052 } 6053 } 6054 6055 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) { 6056 _allocator->decrease_used(bytes); 6057 } 6058 6059 class G1ParCleanupCTTask : public AbstractGangTask { 6060 G1SATBCardTableModRefBS* _ct_bs; 6061 G1CollectedHeap* _g1h; 6062 HeapRegion* volatile _su_head; 6063 public: 6064 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs, 6065 G1CollectedHeap* g1h) : 6066 AbstractGangTask("G1 Par Cleanup CT Task"), 6067 _ct_bs(ct_bs), _g1h(g1h) { } 6068 6069 void work(uint worker_id) { 6070 HeapRegion* r; 6071 while (r = _g1h->pop_dirty_cards_region()) { 6072 clear_cards(r); 6073 } 6074 } 6075 6076 void clear_cards(HeapRegion* r) { 6077 // Cards of the survivors should have already been dirtied. 6078 if (!r->is_survivor()) { 6079 _ct_bs->clear(MemRegion(r->bottom(), r->end())); 6080 } 6081 } 6082 }; 6083 6084 #ifndef PRODUCT 6085 class G1VerifyCardTableCleanup: public HeapRegionClosure { 6086 G1CollectedHeap* _g1h; 6087 G1SATBCardTableModRefBS* _ct_bs; 6088 public: 6089 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs) 6090 : _g1h(g1h), _ct_bs(ct_bs) { } 6091 virtual bool doHeapRegion(HeapRegion* r) { 6092 if (r->is_survivor()) { 6093 _g1h->verify_dirty_region(r); 6094 } else { 6095 _g1h->verify_not_dirty_region(r); 6096 } 6097 return false; 6098 } 6099 }; 6100 6101 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) { 6102 // All of the region should be clean. 6103 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 6104 MemRegion mr(hr->bottom(), hr->end()); 6105 ct_bs->verify_not_dirty_region(mr); 6106 } 6107 6108 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) { 6109 // We cannot guarantee that [bottom(),end()] is dirty. Threads 6110 // dirty allocated blocks as they allocate them. The thread that 6111 // retires each region and replaces it with a new one will do a 6112 // maximal allocation to fill in [pre_dummy_top(),end()] but will 6113 // not dirty that area (one less thing to have to do while holding 6114 // a lock). So we can only verify that [bottom(),pre_dummy_top()] 6115 // is dirty. 6116 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 6117 MemRegion mr(hr->bottom(), hr->pre_dummy_top()); 6118 if (hr->is_young()) { 6119 ct_bs->verify_g1_young_region(mr); 6120 } else { 6121 ct_bs->verify_dirty_region(mr); 6122 } 6123 } 6124 6125 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) { 6126 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 6127 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) { 6128 verify_dirty_region(hr); 6129 } 6130 } 6131 6132 void G1CollectedHeap::verify_dirty_young_regions() { 6133 verify_dirty_young_list(_young_list->first_region()); 6134 } 6135 6136 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap, 6137 HeapWord* tams, HeapWord* end) { 6138 guarantee(tams <= end, 6139 err_msg("tams: "PTR_FORMAT" end: "PTR_FORMAT, tams, end)); 6140 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end); 6141 if (result < end) { 6142 gclog_or_tty->cr(); 6143 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: "PTR_FORMAT, 6144 bitmap_name, result); 6145 gclog_or_tty->print_cr("## %s tams: "PTR_FORMAT" end: "PTR_FORMAT, 6146 bitmap_name, tams, end); 6147 return false; 6148 } 6149 return true; 6150 } 6151 6152 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) { 6153 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap(); 6154 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap(); 6155 6156 HeapWord* bottom = hr->bottom(); 6157 HeapWord* ptams = hr->prev_top_at_mark_start(); 6158 HeapWord* ntams = hr->next_top_at_mark_start(); 6159 HeapWord* end = hr->end(); 6160 6161 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end); 6162 6163 bool res_n = true; 6164 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window 6165 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap 6166 // if we happen to be in that state. 6167 if (mark_in_progress() || !_cmThread->in_progress()) { 6168 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end); 6169 } 6170 if (!res_p || !res_n) { 6171 gclog_or_tty->print_cr("#### Bitmap verification failed for "HR_FORMAT, 6172 HR_FORMAT_PARAMS(hr)); 6173 gclog_or_tty->print_cr("#### Caller: %s", caller); 6174 return false; 6175 } 6176 return true; 6177 } 6178 6179 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) { 6180 if (!G1VerifyBitmaps) return; 6181 6182 guarantee(verify_bitmaps(caller, hr), "bitmap verification"); 6183 } 6184 6185 class G1VerifyBitmapClosure : public HeapRegionClosure { 6186 private: 6187 const char* _caller; 6188 G1CollectedHeap* _g1h; 6189 bool _failures; 6190 6191 public: 6192 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) : 6193 _caller(caller), _g1h(g1h), _failures(false) { } 6194 6195 bool failures() { return _failures; } 6196 6197 virtual bool doHeapRegion(HeapRegion* hr) { 6198 if (hr->continuesHumongous()) return false; 6199 6200 bool result = _g1h->verify_bitmaps(_caller, hr); 6201 if (!result) { 6202 _failures = true; 6203 } 6204 return false; 6205 } 6206 }; 6207 6208 void G1CollectedHeap::check_bitmaps(const char* caller) { 6209 if (!G1VerifyBitmaps) return; 6210 6211 G1VerifyBitmapClosure cl(caller, this); 6212 heap_region_iterate(&cl); 6213 guarantee(!cl.failures(), "bitmap verification"); 6214 } 6215 #endif // PRODUCT 6216 6217 void G1CollectedHeap::cleanUpCardTable() { 6218 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 6219 double start = os::elapsedTime(); 6220 6221 { 6222 // Iterate over the dirty cards region list. 6223 G1ParCleanupCTTask cleanup_task(ct_bs, this); 6224 6225 if (G1CollectedHeap::use_parallel_gc_threads()) { 6226 set_par_threads(); 6227 workers()->run_task(&cleanup_task); 6228 set_par_threads(0); 6229 } else { 6230 while (_dirty_cards_region_list) { 6231 HeapRegion* r = _dirty_cards_region_list; 6232 cleanup_task.clear_cards(r); 6233 _dirty_cards_region_list = r->get_next_dirty_cards_region(); 6234 if (_dirty_cards_region_list == r) { 6235 // The last region. 6236 _dirty_cards_region_list = NULL; 6237 } 6238 r->set_next_dirty_cards_region(NULL); 6239 } 6240 } 6241 #ifndef PRODUCT 6242 if (G1VerifyCTCleanup || VerifyAfterGC) { 6243 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs); 6244 heap_region_iterate(&cleanup_verifier); 6245 } 6246 #endif 6247 } 6248 6249 double elapsed = os::elapsedTime() - start; 6250 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0); 6251 } 6252 6253 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) { 6254 size_t pre_used = 0; 6255 FreeRegionList local_free_list("Local List for CSet Freeing"); 6256 6257 double young_time_ms = 0.0; 6258 double non_young_time_ms = 0.0; 6259 6260 // Since the collection set is a superset of the the young list, 6261 // all we need to do to clear the young list is clear its 6262 // head and length, and unlink any young regions in the code below 6263 _young_list->clear(); 6264 6265 G1CollectorPolicy* policy = g1_policy(); 6266 6267 double start_sec = os::elapsedTime(); 6268 bool non_young = true; 6269 6270 HeapRegion* cur = cs_head; 6271 int age_bound = -1; 6272 size_t rs_lengths = 0; 6273 6274 while (cur != NULL) { 6275 assert(!is_on_master_free_list(cur), "sanity"); 6276 if (non_young) { 6277 if (cur->is_young()) { 6278 double end_sec = os::elapsedTime(); 6279 double elapsed_ms = (end_sec - start_sec) * 1000.0; 6280 non_young_time_ms += elapsed_ms; 6281 6282 start_sec = os::elapsedTime(); 6283 non_young = false; 6284 } 6285 } else { 6286 if (!cur->is_young()) { 6287 double end_sec = os::elapsedTime(); 6288 double elapsed_ms = (end_sec - start_sec) * 1000.0; 6289 young_time_ms += elapsed_ms; 6290 6291 start_sec = os::elapsedTime(); 6292 non_young = true; 6293 } 6294 } 6295 6296 rs_lengths += cur->rem_set()->occupied_locked(); 6297 6298 HeapRegion* next = cur->next_in_collection_set(); 6299 assert(cur->in_collection_set(), "bad CS"); 6300 cur->set_next_in_collection_set(NULL); 6301 cur->set_in_collection_set(false); 6302 6303 if (cur->is_young()) { 6304 int index = cur->young_index_in_cset(); 6305 assert(index != -1, "invariant"); 6306 assert((uint) index < policy->young_cset_region_length(), "invariant"); 6307 size_t words_survived = _surviving_young_words[index]; 6308 cur->record_surv_words_in_group(words_survived); 6309 6310 // At this point the we have 'popped' cur from the collection set 6311 // (linked via next_in_collection_set()) but it is still in the 6312 // young list (linked via next_young_region()). Clear the 6313 // _next_young_region field. 6314 cur->set_next_young_region(NULL); 6315 } else { 6316 int index = cur->young_index_in_cset(); 6317 assert(index == -1, "invariant"); 6318 } 6319 6320 assert( (cur->is_young() && cur->young_index_in_cset() > -1) || 6321 (!cur->is_young() && cur->young_index_in_cset() == -1), 6322 "invariant" ); 6323 6324 if (!cur->evacuation_failed()) { 6325 MemRegion used_mr = cur->used_region(); 6326 6327 // And the region is empty. 6328 assert(!used_mr.is_empty(), "Should not have empty regions in a CS."); 6329 pre_used += cur->used(); 6330 free_region(cur, &local_free_list, false /* par */, true /* locked */); 6331 } else { 6332 cur->uninstall_surv_rate_group(); 6333 if (cur->is_young()) { 6334 cur->set_young_index_in_cset(-1); 6335 } 6336 cur->set_evacuation_failed(false); 6337 // The region is now considered to be old. 6338 cur->set_old(); 6339 _old_set.add(cur); 6340 evacuation_info.increment_collectionset_used_after(cur->used()); 6341 } 6342 cur = next; 6343 } 6344 6345 evacuation_info.set_regions_freed(local_free_list.length()); 6346 policy->record_max_rs_lengths(rs_lengths); 6347 policy->cset_regions_freed(); 6348 6349 double end_sec = os::elapsedTime(); 6350 double elapsed_ms = (end_sec - start_sec) * 1000.0; 6351 6352 if (non_young) { 6353 non_young_time_ms += elapsed_ms; 6354 } else { 6355 young_time_ms += elapsed_ms; 6356 } 6357 6358 prepend_to_freelist(&local_free_list); 6359 decrement_summary_bytes(pre_used); 6360 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms); 6361 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms); 6362 } 6363 6364 class G1FreeHumongousRegionClosure : public HeapRegionClosure { 6365 private: 6366 FreeRegionList* _free_region_list; 6367 HeapRegionSet* _proxy_set; 6368 HeapRegionSetCount _humongous_regions_removed; 6369 size_t _freed_bytes; 6370 public: 6371 6372 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) : 6373 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) { 6374 } 6375 6376 virtual bool doHeapRegion(HeapRegion* r) { 6377 if (!r->startsHumongous()) { 6378 return false; 6379 } 6380 6381 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 6382 6383 oop obj = (oop)r->bottom(); 6384 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap(); 6385 6386 // The following checks whether the humongous object is live are sufficient. 6387 // The main additional check (in addition to having a reference from the roots 6388 // or the young gen) is whether the humongous object has a remembered set entry. 6389 // 6390 // A humongous object cannot be live if there is no remembered set for it 6391 // because: 6392 // - there can be no references from within humongous starts regions referencing 6393 // the object because we never allocate other objects into them. 6394 // (I.e. there are no intra-region references that may be missed by the 6395 // remembered set) 6396 // - as soon there is a remembered set entry to the humongous starts region 6397 // (i.e. it has "escaped" to an old object) this remembered set entry will stay 6398 // until the end of a concurrent mark. 6399 // 6400 // It is not required to check whether the object has been found dead by marking 6401 // or not, in fact it would prevent reclamation within a concurrent cycle, as 6402 // all objects allocated during that time are considered live. 6403 // SATB marking is even more conservative than the remembered set. 6404 // So if at this point in the collection there is no remembered set entry, 6405 // nobody has a reference to it. 6406 // At the start of collection we flush all refinement logs, and remembered sets 6407 // are completely up-to-date wrt to references to the humongous object. 6408 // 6409 // Other implementation considerations: 6410 // - never consider object arrays: while they are a valid target, they have not 6411 // been observed to be used as temporary objects. 6412 // - they would also pose considerable effort for cleaning up the the remembered 6413 // sets. 6414 // While this cleanup is not strictly necessary to be done (or done instantly), 6415 // given that their occurrence is very low, this saves us this additional 6416 // complexity. 6417 uint region_idx = r->hrm_index(); 6418 if (g1h->humongous_is_live(region_idx) || 6419 g1h->humongous_region_is_always_live(region_idx)) { 6420 6421 if (G1TraceReclaimDeadHumongousObjectsAtYoungGC) { 6422 gclog_or_tty->print_cr("Live humongous %d region %d with remset "SIZE_FORMAT" code roots "SIZE_FORMAT" is marked %d live-other %d obj array %d", 6423 r->isHumongous(), 6424 region_idx, 6425 r->rem_set()->occupied(), 6426 r->rem_set()->strong_code_roots_list_length(), 6427 next_bitmap->isMarked(r->bottom()), 6428 g1h->humongous_is_live(region_idx), 6429 obj->is_objArray() 6430 ); 6431 } 6432 6433 return false; 6434 } 6435 6436 guarantee(!obj->is_objArray(), 6437 err_msg("Eagerly reclaiming object arrays is not supported, but the object "PTR_FORMAT" is.", 6438 r->bottom())); 6439 6440 if (G1TraceReclaimDeadHumongousObjectsAtYoungGC) { 6441 gclog_or_tty->print_cr("Reclaim humongous region %d start "PTR_FORMAT" region %d length "UINT32_FORMAT" with remset "SIZE_FORMAT" code roots "SIZE_FORMAT" is marked %d live-other %d obj array %d", 6442 r->isHumongous(), 6443 r->bottom(), 6444 region_idx, 6445 r->region_num(), 6446 r->rem_set()->occupied(), 6447 r->rem_set()->strong_code_roots_list_length(), 6448 next_bitmap->isMarked(r->bottom()), 6449 g1h->humongous_is_live(region_idx), 6450 obj->is_objArray() 6451 ); 6452 } 6453 // Need to clear mark bit of the humongous object if already set. 6454 if (next_bitmap->isMarked(r->bottom())) { 6455 next_bitmap->clear(r->bottom()); 6456 } 6457 _freed_bytes += r->used(); 6458 r->set_containing_set(NULL); 6459 _humongous_regions_removed.increment(1u, r->capacity()); 6460 g1h->free_humongous_region(r, _free_region_list, false); 6461 6462 return false; 6463 } 6464 6465 HeapRegionSetCount& humongous_free_count() { 6466 return _humongous_regions_removed; 6467 } 6468 6469 size_t bytes_freed() const { 6470 return _freed_bytes; 6471 } 6472 6473 size_t humongous_reclaimed() const { 6474 return _humongous_regions_removed.length(); 6475 } 6476 }; 6477 6478 void G1CollectedHeap::eagerly_reclaim_humongous_regions() { 6479 assert_at_safepoint(true); 6480 6481 if (!G1ReclaimDeadHumongousObjectsAtYoungGC || !_has_humongous_reclaim_candidates) { 6482 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0); 6483 return; 6484 } 6485 6486 double start_time = os::elapsedTime(); 6487 6488 FreeRegionList local_cleanup_list("Local Humongous Cleanup List"); 6489 6490 G1FreeHumongousRegionClosure cl(&local_cleanup_list); 6491 heap_region_iterate(&cl); 6492 6493 HeapRegionSetCount empty_set; 6494 remove_from_old_sets(empty_set, cl.humongous_free_count()); 6495 6496 G1HRPrinter* hr_printer = _g1h->hr_printer(); 6497 if (hr_printer->is_active()) { 6498 FreeRegionListIterator iter(&local_cleanup_list); 6499 while (iter.more_available()) { 6500 HeapRegion* hr = iter.get_next(); 6501 hr_printer->cleanup(hr); 6502 } 6503 } 6504 6505 prepend_to_freelist(&local_cleanup_list); 6506 decrement_summary_bytes(cl.bytes_freed()); 6507 6508 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0, 6509 cl.humongous_reclaimed()); 6510 } 6511 6512 // This routine is similar to the above but does not record 6513 // any policy statistics or update free lists; we are abandoning 6514 // the current incremental collection set in preparation of a 6515 // full collection. After the full GC we will start to build up 6516 // the incremental collection set again. 6517 // This is only called when we're doing a full collection 6518 // and is immediately followed by the tearing down of the young list. 6519 6520 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) { 6521 HeapRegion* cur = cs_head; 6522 6523 while (cur != NULL) { 6524 HeapRegion* next = cur->next_in_collection_set(); 6525 assert(cur->in_collection_set(), "bad CS"); 6526 cur->set_next_in_collection_set(NULL); 6527 cur->set_in_collection_set(false); 6528 cur->set_young_index_in_cset(-1); 6529 cur = next; 6530 } 6531 } 6532 6533 void G1CollectedHeap::set_free_regions_coming() { 6534 if (G1ConcRegionFreeingVerbose) { 6535 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " 6536 "setting free regions coming"); 6537 } 6538 6539 assert(!free_regions_coming(), "pre-condition"); 6540 _free_regions_coming = true; 6541 } 6542 6543 void G1CollectedHeap::reset_free_regions_coming() { 6544 assert(free_regions_coming(), "pre-condition"); 6545 6546 { 6547 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6548 _free_regions_coming = false; 6549 SecondaryFreeList_lock->notify_all(); 6550 } 6551 6552 if (G1ConcRegionFreeingVerbose) { 6553 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " 6554 "reset free regions coming"); 6555 } 6556 } 6557 6558 void G1CollectedHeap::wait_while_free_regions_coming() { 6559 // Most of the time we won't have to wait, so let's do a quick test 6560 // first before we take the lock. 6561 if (!free_regions_coming()) { 6562 return; 6563 } 6564 6565 if (G1ConcRegionFreeingVerbose) { 6566 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " 6567 "waiting for free regions"); 6568 } 6569 6570 { 6571 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6572 while (free_regions_coming()) { 6573 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 6574 } 6575 } 6576 6577 if (G1ConcRegionFreeingVerbose) { 6578 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " 6579 "done waiting for free regions"); 6580 } 6581 } 6582 6583 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 6584 assert(heap_lock_held_for_gc(), 6585 "the heap lock should already be held by or for this thread"); 6586 _young_list->push_region(hr); 6587 } 6588 6589 class NoYoungRegionsClosure: public HeapRegionClosure { 6590 private: 6591 bool _success; 6592 public: 6593 NoYoungRegionsClosure() : _success(true) { } 6594 bool doHeapRegion(HeapRegion* r) { 6595 if (r->is_young()) { 6596 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young", 6597 r->bottom(), r->end()); 6598 _success = false; 6599 } 6600 return false; 6601 } 6602 bool success() { return _success; } 6603 }; 6604 6605 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) { 6606 bool ret = _young_list->check_list_empty(check_sample); 6607 6608 if (check_heap) { 6609 NoYoungRegionsClosure closure; 6610 heap_region_iterate(&closure); 6611 ret = ret && closure.success(); 6612 } 6613 6614 return ret; 6615 } 6616 6617 class TearDownRegionSetsClosure : public HeapRegionClosure { 6618 private: 6619 HeapRegionSet *_old_set; 6620 6621 public: 6622 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { } 6623 6624 bool doHeapRegion(HeapRegion* r) { 6625 if (r->is_old()) { 6626 _old_set->remove(r); 6627 } else { 6628 // We ignore free regions, we'll empty the free list afterwards. 6629 // We ignore young regions, we'll empty the young list afterwards. 6630 // We ignore humongous regions, we're not tearing down the 6631 // humongous regions set. 6632 assert(r->is_free() || r->is_young() || r->isHumongous(), 6633 "it cannot be another type"); 6634 } 6635 return false; 6636 } 6637 6638 ~TearDownRegionSetsClosure() { 6639 assert(_old_set->is_empty(), "post-condition"); 6640 } 6641 }; 6642 6643 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) { 6644 assert_at_safepoint(true /* should_be_vm_thread */); 6645 6646 if (!free_list_only) { 6647 TearDownRegionSetsClosure cl(&_old_set); 6648 heap_region_iterate(&cl); 6649 6650 // Note that emptying the _young_list is postponed and instead done as 6651 // the first step when rebuilding the regions sets again. The reason for 6652 // this is that during a full GC string deduplication needs to know if 6653 // a collected region was young or old when the full GC was initiated. 6654 } 6655 _hrm.remove_all_free_regions(); 6656 } 6657 6658 class RebuildRegionSetsClosure : public HeapRegionClosure { 6659 private: 6660 bool _free_list_only; 6661 HeapRegionSet* _old_set; 6662 HeapRegionManager* _hrm; 6663 size_t _total_used; 6664 6665 public: 6666 RebuildRegionSetsClosure(bool free_list_only, 6667 HeapRegionSet* old_set, HeapRegionManager* hrm) : 6668 _free_list_only(free_list_only), 6669 _old_set(old_set), _hrm(hrm), _total_used(0) { 6670 assert(_hrm->num_free_regions() == 0, "pre-condition"); 6671 if (!free_list_only) { 6672 assert(_old_set->is_empty(), "pre-condition"); 6673 } 6674 } 6675 6676 bool doHeapRegion(HeapRegion* r) { 6677 if (r->continuesHumongous()) { 6678 return false; 6679 } 6680 6681 if (r->is_empty()) { 6682 // Add free regions to the free list 6683 r->set_free(); 6684 r->set_allocation_context(AllocationContext::system()); 6685 _hrm->insert_into_free_list(r); 6686 } else if (!_free_list_only) { 6687 assert(!r->is_young(), "we should not come across young regions"); 6688 6689 if (r->isHumongous()) { 6690 // We ignore humongous regions, we left the humongous set unchanged 6691 } else { 6692 // Objects that were compacted would have ended up on regions 6693 // that were previously old or free. 6694 assert(r->is_free() || r->is_old(), "invariant"); 6695 // We now consider them old, so register as such. 6696 r->set_old(); 6697 _old_set->add(r); 6698 } 6699 _total_used += r->used(); 6700 } 6701 6702 return false; 6703 } 6704 6705 size_t total_used() { 6706 return _total_used; 6707 } 6708 }; 6709 6710 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { 6711 assert_at_safepoint(true /* should_be_vm_thread */); 6712 6713 if (!free_list_only) { 6714 _young_list->empty_list(); 6715 } 6716 6717 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm); 6718 heap_region_iterate(&cl); 6719 6720 if (!free_list_only) { 6721 _allocator->set_used(cl.total_used()); 6722 } 6723 assert(_allocator->used_unlocked() == recalculate_used(), 6724 err_msg("inconsistent _allocator->used_unlocked(), " 6725 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT, 6726 _allocator->used_unlocked(), recalculate_used())); 6727 } 6728 6729 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) { 6730 _refine_cte_cl->set_concurrent(concurrent); 6731 } 6732 6733 bool G1CollectedHeap::is_in_closed_subset(const void* p) const { 6734 HeapRegion* hr = heap_region_containing(p); 6735 return hr->is_in(p); 6736 } 6737 6738 // Methods for the mutator alloc region 6739 6740 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 6741 bool force) { 6742 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6743 assert(!force || g1_policy()->can_expand_young_list(), 6744 "if force is true we should be able to expand the young list"); 6745 bool young_list_full = g1_policy()->is_young_list_full(); 6746 if (force || !young_list_full) { 6747 HeapRegion* new_alloc_region = new_region(word_size, 6748 false /* is_old */, 6749 false /* do_expand */); 6750 if (new_alloc_region != NULL) { 6751 set_region_short_lived_locked(new_alloc_region); 6752 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full); 6753 check_bitmaps("Mutator Region Allocation", new_alloc_region); 6754 return new_alloc_region; 6755 } 6756 } 6757 return NULL; 6758 } 6759 6760 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 6761 size_t allocated_bytes) { 6762 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6763 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden"); 6764 6765 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region); 6766 _allocator->increase_used(allocated_bytes); 6767 _hr_printer.retire(alloc_region); 6768 // We update the eden sizes here, when the region is retired, 6769 // instead of when it's allocated, since this is the point that its 6770 // used space has been recored in _summary_bytes_used. 6771 g1mm()->update_eden_size(); 6772 } 6773 6774 void G1CollectedHeap::set_par_threads() { 6775 // Don't change the number of workers. Use the value previously set 6776 // in the workgroup. 6777 assert(G1CollectedHeap::use_parallel_gc_threads(), "shouldn't be here otherwise"); 6778 uint n_workers = workers()->active_workers(); 6779 assert(UseDynamicNumberOfGCThreads || 6780 n_workers == workers()->total_workers(), 6781 "Otherwise should be using the total number of workers"); 6782 if (n_workers == 0) { 6783 assert(false, "Should have been set in prior evacuation pause."); 6784 n_workers = ParallelGCThreads; 6785 workers()->set_active_workers(n_workers); 6786 } 6787 set_par_threads(n_workers); 6788 } 6789 6790 // Methods for the GC alloc regions 6791 6792 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, 6793 uint count, 6794 GCAllocPurpose ap) { 6795 assert(FreeList_lock->owned_by_self(), "pre-condition"); 6796 6797 if (count < g1_policy()->max_regions(ap)) { 6798 bool survivor = (ap == GCAllocForSurvived); 6799 HeapRegion* new_alloc_region = new_region(word_size, 6800 !survivor, 6801 true /* do_expand */); 6802 if (new_alloc_region != NULL) { 6803 // We really only need to do this for old regions given that we 6804 // should never scan survivors. But it doesn't hurt to do it 6805 // for survivors too. 6806 new_alloc_region->record_top_and_timestamp(); 6807 if (survivor) { 6808 new_alloc_region->set_survivor(); 6809 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor); 6810 check_bitmaps("Survivor Region Allocation", new_alloc_region); 6811 } else { 6812 new_alloc_region->set_old(); 6813 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old); 6814 check_bitmaps("Old Region Allocation", new_alloc_region); 6815 } 6816 bool during_im = g1_policy()->during_initial_mark_pause(); 6817 new_alloc_region->note_start_of_copying(during_im); 6818 return new_alloc_region; 6819 } else { 6820 g1_policy()->note_alloc_region_limit_reached(ap); 6821 } 6822 } 6823 return NULL; 6824 } 6825 6826 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 6827 size_t allocated_bytes, 6828 GCAllocPurpose ap) { 6829 bool during_im = g1_policy()->during_initial_mark_pause(); 6830 alloc_region->note_end_of_copying(during_im); 6831 g1_policy()->record_bytes_copied_during_gc(allocated_bytes); 6832 if (ap == GCAllocForSurvived) { 6833 young_list()->add_survivor_region(alloc_region); 6834 } else { 6835 _old_set.add(alloc_region); 6836 } 6837 _hr_printer.retire(alloc_region); 6838 } 6839 6840 // Heap region set verification 6841 6842 class VerifyRegionListsClosure : public HeapRegionClosure { 6843 private: 6844 HeapRegionSet* _old_set; 6845 HeapRegionSet* _humongous_set; 6846 HeapRegionManager* _hrm; 6847 6848 public: 6849 HeapRegionSetCount _old_count; 6850 HeapRegionSetCount _humongous_count; 6851 HeapRegionSetCount _free_count; 6852 6853 VerifyRegionListsClosure(HeapRegionSet* old_set, 6854 HeapRegionSet* humongous_set, 6855 HeapRegionManager* hrm) : 6856 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm), 6857 _old_count(), _humongous_count(), _free_count(){ } 6858 6859 bool doHeapRegion(HeapRegion* hr) { 6860 if (hr->continuesHumongous()) { 6861 return false; 6862 } 6863 6864 if (hr->is_young()) { 6865 // TODO 6866 } else if (hr->startsHumongous()) { 6867 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrm_index())); 6868 _humongous_count.increment(1u, hr->capacity()); 6869 } else if (hr->is_empty()) { 6870 assert(_hrm->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrm_index())); 6871 _free_count.increment(1u, hr->capacity()); 6872 } else if (hr->is_old()) { 6873 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrm_index())); 6874 _old_count.increment(1u, hr->capacity()); 6875 } else { 6876 ShouldNotReachHere(); 6877 } 6878 return false; 6879 } 6880 6881 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) { 6882 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length())); 6883 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6884 old_set->total_capacity_bytes(), _old_count.capacity())); 6885 6886 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length())); 6887 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6888 humongous_set->total_capacity_bytes(), _humongous_count.capacity())); 6889 6890 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())); 6891 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6892 free_list->total_capacity_bytes(), _free_count.capacity())); 6893 } 6894 }; 6895 6896 void G1CollectedHeap::verify_region_sets() { 6897 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6898 6899 // First, check the explicit lists. 6900 _hrm.verify(); 6901 { 6902 // Given that a concurrent operation might be adding regions to 6903 // the secondary free list we have to take the lock before 6904 // verifying it. 6905 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6906 _secondary_free_list.verify_list(); 6907 } 6908 6909 // If a concurrent region freeing operation is in progress it will 6910 // be difficult to correctly attributed any free regions we come 6911 // across to the correct free list given that they might belong to 6912 // one of several (free_list, secondary_free_list, any local lists, 6913 // etc.). So, if that's the case we will skip the rest of the 6914 // verification operation. Alternatively, waiting for the concurrent 6915 // operation to complete will have a non-trivial effect on the GC's 6916 // operation (no concurrent operation will last longer than the 6917 // interval between two calls to verification) and it might hide 6918 // any issues that we would like to catch during testing. 6919 if (free_regions_coming()) { 6920 return; 6921 } 6922 6923 // Make sure we append the secondary_free_list on the free_list so 6924 // that all free regions we will come across can be safely 6925 // attributed to the free_list. 6926 append_secondary_free_list_if_not_empty_with_lock(); 6927 6928 // Finally, make sure that the region accounting in the lists is 6929 // consistent with what we see in the heap. 6930 6931 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm); 6932 heap_region_iterate(&cl); 6933 cl.verify_counts(&_old_set, &_humongous_set, &_hrm); 6934 } 6935 6936 // Optimized nmethod scanning 6937 6938 class RegisterNMethodOopClosure: public OopClosure { 6939 G1CollectedHeap* _g1h; 6940 nmethod* _nm; 6941 6942 template <class T> void do_oop_work(T* p) { 6943 T heap_oop = oopDesc::load_heap_oop(p); 6944 if (!oopDesc::is_null(heap_oop)) { 6945 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 6946 HeapRegion* hr = _g1h->heap_region_containing(obj); 6947 assert(!hr->continuesHumongous(), 6948 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT 6949 " starting at "HR_FORMAT, 6950 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()))); 6951 6952 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries. 6953 hr->add_strong_code_root_locked(_nm); 6954 } 6955 } 6956 6957 public: 6958 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 6959 _g1h(g1h), _nm(nm) {} 6960 6961 void do_oop(oop* p) { do_oop_work(p); } 6962 void do_oop(narrowOop* p) { do_oop_work(p); } 6963 }; 6964 6965 class UnregisterNMethodOopClosure: public OopClosure { 6966 G1CollectedHeap* _g1h; 6967 nmethod* _nm; 6968 6969 template <class T> void do_oop_work(T* p) { 6970 T heap_oop = oopDesc::load_heap_oop(p); 6971 if (!oopDesc::is_null(heap_oop)) { 6972 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 6973 HeapRegion* hr = _g1h->heap_region_containing(obj); 6974 assert(!hr->continuesHumongous(), 6975 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT 6976 " starting at "HR_FORMAT, 6977 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()))); 6978 6979 hr->remove_strong_code_root(_nm); 6980 } 6981 } 6982 6983 public: 6984 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 6985 _g1h(g1h), _nm(nm) {} 6986 6987 void do_oop(oop* p) { do_oop_work(p); } 6988 void do_oop(narrowOop* p) { do_oop_work(p); } 6989 }; 6990 6991 void G1CollectedHeap::register_nmethod(nmethod* nm) { 6992 CollectedHeap::register_nmethod(nm); 6993 6994 guarantee(nm != NULL, "sanity"); 6995 RegisterNMethodOopClosure reg_cl(this, nm); 6996 nm->oops_do(®_cl); 6997 } 6998 6999 void G1CollectedHeap::unregister_nmethod(nmethod* nm) { 7000 CollectedHeap::unregister_nmethod(nm); 7001 7002 guarantee(nm != NULL, "sanity"); 7003 UnregisterNMethodOopClosure reg_cl(this, nm); 7004 nm->oops_do(®_cl, true); 7005 } 7006 7007 void G1CollectedHeap::purge_code_root_memory() { 7008 double purge_start = os::elapsedTime(); 7009 G1CodeRootSet::purge(); 7010 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0; 7011 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms); 7012 } 7013 7014 class RebuildStrongCodeRootClosure: public CodeBlobClosure { 7015 G1CollectedHeap* _g1h; 7016 7017 public: 7018 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) : 7019 _g1h(g1h) {} 7020 7021 void do_code_blob(CodeBlob* cb) { 7022 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL; 7023 if (nm == NULL) { 7024 return; 7025 } 7026 7027 if (ScavengeRootsInCode) { 7028 _g1h->register_nmethod(nm); 7029 } 7030 } 7031 }; 7032 7033 void G1CollectedHeap::rebuild_strong_code_roots() { 7034 RebuildStrongCodeRootClosure blob_cl(this); 7035 CodeCache::blobs_do(&blob_cl); 7036 }