1 /* 2 * Copyright (c) 2001, 2014, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #if !defined(__clang_major__) && defined(__GNUC__) 26 // FIXME, formats have issues. Disable this macro definition, compile, and study warnings for more information. 27 #define ATTRIBUTE_PRINTF(x,y) 28 #endif 29 30 #include "precompiled.hpp" 31 #include "classfile/stringTable.hpp" 32 #include "code/codeCache.hpp" 33 #include "code/icBuffer.hpp" 34 #include "gc_implementation/g1/bufferingOopClosure.hpp" 35 #include "gc_implementation/g1/concurrentG1Refine.hpp" 36 #include "gc_implementation/g1/concurrentG1RefineThread.hpp" 37 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp" 38 #include "gc_implementation/g1/g1AllocRegion.inline.hpp" 39 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp" 40 #include "gc_implementation/g1/g1CollectorPolicy.hpp" 41 #include "gc_implementation/g1/g1ErgoVerbose.hpp" 42 #include "gc_implementation/g1/g1EvacFailure.hpp" 43 #include "gc_implementation/g1/g1GCPhaseTimes.hpp" 44 #include "gc_implementation/g1/g1Log.hpp" 45 #include "gc_implementation/g1/g1MarkSweep.hpp" 46 #include "gc_implementation/g1/g1OopClosures.inline.hpp" 47 #include "gc_implementation/g1/g1ParScanThreadState.inline.hpp" 48 #include "gc_implementation/g1/g1RegionToSpaceMapper.hpp" 49 #include "gc_implementation/g1/g1RemSet.inline.hpp" 50 #include "gc_implementation/g1/g1StringDedup.hpp" 51 #include "gc_implementation/g1/g1YCTypes.hpp" 52 #include "gc_implementation/g1/heapRegion.inline.hpp" 53 #include "gc_implementation/g1/heapRegionRemSet.hpp" 54 #include "gc_implementation/g1/heapRegionSet.inline.hpp" 55 #include "gc_implementation/g1/vm_operations_g1.hpp" 56 #include "gc_implementation/shared/gcHeapSummary.hpp" 57 #include "gc_implementation/shared/gcTimer.hpp" 58 #include "gc_implementation/shared/gcTrace.hpp" 59 #include "gc_implementation/shared/gcTraceTime.hpp" 60 #include "gc_implementation/shared/isGCActiveMark.hpp" 61 #include "memory/allocation.hpp" 62 #include "memory/gcLocker.inline.hpp" 63 #include "memory/generationSpec.hpp" 64 #include "memory/iterator.hpp" 65 #include "memory/referenceProcessor.hpp" 66 #include "oops/oop.inline.hpp" 67 #include "oops/oop.pcgc.inline.hpp" 68 #include "runtime/atomic.inline.hpp" 69 #include "runtime/orderAccess.inline.hpp" 70 #include "runtime/vmThread.hpp" 71 #include "utilities/globalDefinitions.hpp" 72 73 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0; 74 75 // turn it on so that the contents of the young list (scan-only / 76 // to-be-collected) are printed at "strategic" points before / during 77 // / after the collection --- this is useful for debugging 78 #define YOUNG_LIST_VERBOSE 0 79 // CURRENT STATUS 80 // This file is under construction. Search for "FIXME". 81 82 // INVARIANTS/NOTES 83 // 84 // All allocation activity covered by the G1CollectedHeap interface is 85 // serialized by acquiring the HeapLock. This happens in mem_allocate 86 // and allocate_new_tlab, which are the "entry" points to the 87 // allocation code from the rest of the JVM. (Note that this does not 88 // apply to TLAB allocation, which is not part of this interface: it 89 // is done by clients of this interface.) 90 91 // Notes on implementation of parallelism in different tasks. 92 // 93 // G1ParVerifyTask uses heap_region_par_iterate_chunked() for parallelism. 94 // The number of GC workers is passed to heap_region_par_iterate_chunked(). 95 // It does use run_task() which sets _n_workers in the task. 96 // G1ParTask executes g1_process_roots() -> 97 // SharedHeap::process_roots() which calls eventually to 98 // CardTableModRefBS::par_non_clean_card_iterate_work() which uses 99 // SequentialSubTasksDone. SharedHeap::process_roots() also 100 // directly uses SubTasksDone (_process_strong_tasks field in SharedHeap). 101 // 102 103 // Local to this file. 104 105 class RefineCardTableEntryClosure: public CardTableEntryClosure { 106 bool _concurrent; 107 public: 108 RefineCardTableEntryClosure() : _concurrent(true) { } 109 110 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 111 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false); 112 // This path is executed by the concurrent refine or mutator threads, 113 // concurrently, and so we do not care if card_ptr contains references 114 // that point into the collection set. 115 assert(!oops_into_cset, "should be"); 116 117 if (_concurrent && SuspendibleThreadSet::should_yield()) { 118 // Caller will actually yield. 119 return false; 120 } 121 // Otherwise, we finished successfully; return true. 122 return true; 123 } 124 125 void set_concurrent(bool b) { _concurrent = b; } 126 }; 127 128 129 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure { 130 size_t _num_processed; 131 CardTableModRefBS* _ctbs; 132 int _histo[256]; 133 134 public: 135 ClearLoggedCardTableEntryClosure() : 136 _num_processed(0), _ctbs(G1CollectedHeap::heap()->g1_barrier_set()) 137 { 138 for (int i = 0; i < 256; i++) _histo[i] = 0; 139 } 140 141 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 142 unsigned char* ujb = (unsigned char*)card_ptr; 143 int ind = (int)(*ujb); 144 _histo[ind]++; 145 146 *card_ptr = (jbyte)CardTableModRefBS::clean_card_val(); 147 _num_processed++; 148 149 return true; 150 } 151 152 size_t num_processed() { return _num_processed; } 153 154 void print_histo() { 155 gclog_or_tty->print_cr("Card table value histogram:"); 156 for (int i = 0; i < 256; i++) { 157 if (_histo[i] != 0) { 158 gclog_or_tty->print_cr(" %d: %d", i, _histo[i]); 159 } 160 } 161 } 162 }; 163 164 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure { 165 private: 166 size_t _num_processed; 167 168 public: 169 RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { } 170 171 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 172 *card_ptr = CardTableModRefBS::dirty_card_val(); 173 _num_processed++; 174 return true; 175 } 176 177 size_t num_processed() const { return _num_processed; } 178 }; 179 180 YoungList::YoungList(G1CollectedHeap* g1h) : 181 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0), 182 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) { 183 guarantee(check_list_empty(false), "just making sure..."); 184 } 185 186 void YoungList::push_region(HeapRegion *hr) { 187 assert(!hr->is_young(), "should not already be young"); 188 assert(hr->get_next_young_region() == NULL, "cause it should!"); 189 190 hr->set_next_young_region(_head); 191 _head = hr; 192 193 _g1h->g1_policy()->set_region_eden(hr, (int) _length); 194 ++_length; 195 } 196 197 void YoungList::add_survivor_region(HeapRegion* hr) { 198 assert(hr->is_survivor(), "should be flagged as survivor region"); 199 assert(hr->get_next_young_region() == NULL, "cause it should!"); 200 201 hr->set_next_young_region(_survivor_head); 202 if (_survivor_head == NULL) { 203 _survivor_tail = hr; 204 } 205 _survivor_head = hr; 206 ++_survivor_length; 207 } 208 209 void YoungList::empty_list(HeapRegion* list) { 210 while (list != NULL) { 211 HeapRegion* next = list->get_next_young_region(); 212 list->set_next_young_region(NULL); 213 list->uninstall_surv_rate_group(); 214 // This is called before a Full GC and all the non-empty / 215 // non-humongous regions at the end of the Full GC will end up as 216 // old anyway. 217 list->set_old(); 218 list = next; 219 } 220 } 221 222 void YoungList::empty_list() { 223 assert(check_list_well_formed(), "young list should be well formed"); 224 225 empty_list(_head); 226 _head = NULL; 227 _length = 0; 228 229 empty_list(_survivor_head); 230 _survivor_head = NULL; 231 _survivor_tail = NULL; 232 _survivor_length = 0; 233 234 _last_sampled_rs_lengths = 0; 235 236 assert(check_list_empty(false), "just making sure..."); 237 } 238 239 bool YoungList::check_list_well_formed() { 240 bool ret = true; 241 242 uint length = 0; 243 HeapRegion* curr = _head; 244 HeapRegion* last = NULL; 245 while (curr != NULL) { 246 if (!curr->is_young()) { 247 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" " 248 "incorrectly tagged (y: %d, surv: %d)", 249 curr->bottom(), curr->end(), 250 curr->is_young(), curr->is_survivor()); 251 ret = false; 252 } 253 ++length; 254 last = curr; 255 curr = curr->get_next_young_region(); 256 } 257 ret = ret && (length == _length); 258 259 if (!ret) { 260 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!"); 261 gclog_or_tty->print_cr("### list has %u entries, _length is %u", 262 length, _length); 263 } 264 265 return ret; 266 } 267 268 bool YoungList::check_list_empty(bool check_sample) { 269 bool ret = true; 270 271 if (_length != 0) { 272 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u", 273 _length); 274 ret = false; 275 } 276 if (check_sample && _last_sampled_rs_lengths != 0) { 277 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths"); 278 ret = false; 279 } 280 if (_head != NULL) { 281 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head"); 282 ret = false; 283 } 284 if (!ret) { 285 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty"); 286 } 287 288 return ret; 289 } 290 291 void 292 YoungList::rs_length_sampling_init() { 293 _sampled_rs_lengths = 0; 294 _curr = _head; 295 } 296 297 bool 298 YoungList::rs_length_sampling_more() { 299 return _curr != NULL; 300 } 301 302 void 303 YoungList::rs_length_sampling_next() { 304 assert( _curr != NULL, "invariant" ); 305 size_t rs_length = _curr->rem_set()->occupied(); 306 307 _sampled_rs_lengths += rs_length; 308 309 // The current region may not yet have been added to the 310 // incremental collection set (it gets added when it is 311 // retired as the current allocation region). 312 if (_curr->in_collection_set()) { 313 // Update the collection set policy information for this region 314 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length); 315 } 316 317 _curr = _curr->get_next_young_region(); 318 if (_curr == NULL) { 319 _last_sampled_rs_lengths = _sampled_rs_lengths; 320 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths); 321 } 322 } 323 324 void 325 YoungList::reset_auxilary_lists() { 326 guarantee( is_empty(), "young list should be empty" ); 327 assert(check_list_well_formed(), "young list should be well formed"); 328 329 // Add survivor regions to SurvRateGroup. 330 _g1h->g1_policy()->note_start_adding_survivor_regions(); 331 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */); 332 333 int young_index_in_cset = 0; 334 for (HeapRegion* curr = _survivor_head; 335 curr != NULL; 336 curr = curr->get_next_young_region()) { 337 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset); 338 339 // The region is a non-empty survivor so let's add it to 340 // the incremental collection set for the next evacuation 341 // pause. 342 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr); 343 young_index_in_cset += 1; 344 } 345 assert((uint) young_index_in_cset == _survivor_length, "post-condition"); 346 _g1h->g1_policy()->note_stop_adding_survivor_regions(); 347 348 _head = _survivor_head; 349 _length = _survivor_length; 350 if (_survivor_head != NULL) { 351 assert(_survivor_tail != NULL, "cause it shouldn't be"); 352 assert(_survivor_length > 0, "invariant"); 353 _survivor_tail->set_next_young_region(NULL); 354 } 355 356 // Don't clear the survivor list handles until the start of 357 // the next evacuation pause - we need it in order to re-tag 358 // the survivor regions from this evacuation pause as 'young' 359 // at the start of the next. 360 361 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */); 362 363 assert(check_list_well_formed(), "young list should be well formed"); 364 } 365 366 void YoungList::print() { 367 HeapRegion* lists[] = {_head, _survivor_head}; 368 const char* names[] = {"YOUNG", "SURVIVOR"}; 369 370 for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) { 371 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]); 372 HeapRegion *curr = lists[list]; 373 if (curr == NULL) 374 gclog_or_tty->print_cr(" empty"); 375 while (curr != NULL) { 376 gclog_or_tty->print_cr(" "HR_FORMAT", P: "PTR_FORMAT ", N: "PTR_FORMAT", age: %4d", 377 HR_FORMAT_PARAMS(curr), 378 curr->prev_top_at_mark_start(), 379 curr->next_top_at_mark_start(), 380 curr->age_in_surv_rate_group_cond()); 381 curr = curr->get_next_young_region(); 382 } 383 } 384 385 gclog_or_tty->cr(); 386 } 387 388 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) { 389 OtherRegionsTable::invalidate(start_idx, num_regions); 390 } 391 392 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions) { 393 reset_from_card_cache(start_idx, num_regions); 394 } 395 396 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr) 397 { 398 // Claim the right to put the region on the dirty cards region list 399 // by installing a self pointer. 400 HeapRegion* next = hr->get_next_dirty_cards_region(); 401 if (next == NULL) { 402 HeapRegion* res = (HeapRegion*) 403 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(), 404 NULL); 405 if (res == NULL) { 406 HeapRegion* head; 407 do { 408 // Put the region to the dirty cards region list. 409 head = _dirty_cards_region_list; 410 next = (HeapRegion*) 411 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head); 412 if (next == head) { 413 assert(hr->get_next_dirty_cards_region() == hr, 414 "hr->get_next_dirty_cards_region() != hr"); 415 if (next == NULL) { 416 // The last region in the list points to itself. 417 hr->set_next_dirty_cards_region(hr); 418 } else { 419 hr->set_next_dirty_cards_region(next); 420 } 421 } 422 } while (next != head); 423 } 424 } 425 } 426 427 HeapRegion* G1CollectedHeap::pop_dirty_cards_region() 428 { 429 HeapRegion* head; 430 HeapRegion* hr; 431 do { 432 head = _dirty_cards_region_list; 433 if (head == NULL) { 434 return NULL; 435 } 436 HeapRegion* new_head = head->get_next_dirty_cards_region(); 437 if (head == new_head) { 438 // The last region. 439 new_head = NULL; 440 } 441 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list, 442 head); 443 } while (hr != head); 444 assert(hr != NULL, "invariant"); 445 hr->set_next_dirty_cards_region(NULL); 446 return hr; 447 } 448 449 #ifdef ASSERT 450 // A region is added to the collection set as it is retired 451 // so an address p can point to a region which will be in the 452 // collection set but has not yet been retired. This method 453 // therefore is only accurate during a GC pause after all 454 // regions have been retired. It is used for debugging 455 // to check if an nmethod has references to objects that can 456 // be move during a partial collection. Though it can be 457 // inaccurate, it is sufficient for G1 because the conservative 458 // implementation of is_scavengable() for G1 will indicate that 459 // all nmethods must be scanned during a partial collection. 460 bool G1CollectedHeap::is_in_partial_collection(const void* p) { 461 if (p == NULL) { 462 return false; 463 } 464 return heap_region_containing(p)->in_collection_set(); 465 } 466 #endif 467 468 // Returns true if the reference points to an object that 469 // can move in an incremental collection. 470 bool G1CollectedHeap::is_scavengable(const void* p) { 471 HeapRegion* hr = heap_region_containing(p); 472 return !hr->is_humongous(); 473 } 474 475 void G1CollectedHeap::check_ct_logs_at_safepoint() { 476 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 477 CardTableModRefBS* ct_bs = g1_barrier_set(); 478 479 // Count the dirty cards at the start. 480 CountNonCleanMemRegionClosure count1(this); 481 ct_bs->mod_card_iterate(&count1); 482 int orig_count = count1.n(); 483 484 // First clear the logged cards. 485 ClearLoggedCardTableEntryClosure clear; 486 dcqs.apply_closure_to_all_completed_buffers(&clear); 487 dcqs.iterate_closure_all_threads(&clear, false); 488 clear.print_histo(); 489 490 // Now ensure that there's no dirty cards. 491 CountNonCleanMemRegionClosure count2(this); 492 ct_bs->mod_card_iterate(&count2); 493 if (count2.n() != 0) { 494 gclog_or_tty->print_cr("Card table has %d entries; %d originally", 495 count2.n(), orig_count); 496 } 497 guarantee(count2.n() == 0, "Card table should be clean."); 498 499 RedirtyLoggedCardTableEntryClosure redirty; 500 dcqs.apply_closure_to_all_completed_buffers(&redirty); 501 dcqs.iterate_closure_all_threads(&redirty, false); 502 gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.", 503 clear.num_processed(), orig_count); 504 guarantee(redirty.num_processed() == clear.num_processed(), 505 err_msg("Redirtied "SIZE_FORMAT" cards, bug cleared "SIZE_FORMAT, 506 redirty.num_processed(), clear.num_processed())); 507 508 CountNonCleanMemRegionClosure count3(this); 509 ct_bs->mod_card_iterate(&count3); 510 if (count3.n() != orig_count) { 511 gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.", 512 orig_count, count3.n()); 513 guarantee(count3.n() >= orig_count, "Should have restored them all."); 514 } 515 } 516 517 // Private class members. 518 519 G1CollectedHeap* G1CollectedHeap::_g1h; 520 521 // Private methods. 522 523 HeapRegion* 524 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) { 525 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 526 while (!_secondary_free_list.is_empty() || free_regions_coming()) { 527 if (!_secondary_free_list.is_empty()) { 528 if (G1ConcRegionFreeingVerbose) { 529 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 530 "secondary_free_list has %u entries", 531 _secondary_free_list.length()); 532 } 533 // It looks as if there are free regions available on the 534 // secondary_free_list. Let's move them to the free_list and try 535 // again to allocate from it. 536 append_secondary_free_list(); 537 538 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not " 539 "empty we should have moved at least one entry to the free_list"); 540 HeapRegion* res = _hrm.allocate_free_region(is_old); 541 if (G1ConcRegionFreeingVerbose) { 542 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 543 "allocated "HR_FORMAT" from secondary_free_list", 544 HR_FORMAT_PARAMS(res)); 545 } 546 return res; 547 } 548 549 // Wait here until we get notified either when (a) there are no 550 // more free regions coming or (b) some regions have been moved on 551 // the secondary_free_list. 552 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 553 } 554 555 if (G1ConcRegionFreeingVerbose) { 556 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 557 "could not allocate from secondary_free_list"); 558 } 559 return NULL; 560 } 561 562 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) { 563 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords, 564 "the only time we use this to allocate a humongous region is " 565 "when we are allocating a single humongous region"); 566 567 HeapRegion* res; 568 if (G1StressConcRegionFreeing) { 569 if (!_secondary_free_list.is_empty()) { 570 if (G1ConcRegionFreeingVerbose) { 571 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 572 "forced to look at the secondary_free_list"); 573 } 574 res = new_region_try_secondary_free_list(is_old); 575 if (res != NULL) { 576 return res; 577 } 578 } 579 } 580 581 res = _hrm.allocate_free_region(is_old); 582 583 if (res == NULL) { 584 if (G1ConcRegionFreeingVerbose) { 585 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 586 "res == NULL, trying the secondary_free_list"); 587 } 588 res = new_region_try_secondary_free_list(is_old); 589 } 590 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) { 591 // Currently, only attempts to allocate GC alloc regions set 592 // do_expand to true. So, we should only reach here during a 593 // safepoint. If this assumption changes we might have to 594 // reconsider the use of _expand_heap_after_alloc_failure. 595 assert(SafepointSynchronize::is_at_safepoint(), "invariant"); 596 597 ergo_verbose1(ErgoHeapSizing, 598 "attempt heap expansion", 599 ergo_format_reason("region allocation request failed") 600 ergo_format_byte("allocation request"), 601 word_size * HeapWordSize); 602 if (expand(word_size * HeapWordSize)) { 603 // Given that expand() succeeded in expanding the heap, and we 604 // always expand the heap by an amount aligned to the heap 605 // region size, the free list should in theory not be empty. 606 // In either case allocate_free_region() will check for NULL. 607 res = _hrm.allocate_free_region(is_old); 608 } else { 609 _expand_heap_after_alloc_failure = false; 610 } 611 } 612 return res; 613 } 614 615 HeapWord* 616 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first, 617 uint num_regions, 618 size_t word_size, 619 AllocationContext_t context) { 620 assert(first != G1_NO_HRM_INDEX, "pre-condition"); 621 assert(is_humongous(word_size), "word_size should be humongous"); 622 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition"); 623 624 // Index of last region in the series + 1. 625 uint last = first + num_regions; 626 627 // We need to initialize the region(s) we just discovered. This is 628 // a bit tricky given that it can happen concurrently with 629 // refinement threads refining cards on these regions and 630 // potentially wanting to refine the BOT as they are scanning 631 // those cards (this can happen shortly after a cleanup; see CR 632 // 6991377). So we have to set up the region(s) carefully and in 633 // a specific order. 634 635 // The word size sum of all the regions we will allocate. 636 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords; 637 assert(word_size <= word_size_sum, "sanity"); 638 639 // This will be the "starts humongous" region. 640 HeapRegion* first_hr = region_at(first); 641 // The header of the new object will be placed at the bottom of 642 // the first region. 643 HeapWord* new_obj = first_hr->bottom(); 644 // This will be the new end of the first region in the series that 645 // should also match the end of the last region in the series. 646 HeapWord* new_end = new_obj + word_size_sum; 647 // This will be the new top of the first region that will reflect 648 // this allocation. 649 HeapWord* new_top = new_obj + word_size; 650 651 // First, we need to zero the header of the space that we will be 652 // allocating. When we update top further down, some refinement 653 // threads might try to scan the region. By zeroing the header we 654 // ensure that any thread that will try to scan the region will 655 // come across the zero klass word and bail out. 656 // 657 // NOTE: It would not have been correct to have used 658 // CollectedHeap::fill_with_object() and make the space look like 659 // an int array. The thread that is doing the allocation will 660 // later update the object header to a potentially different array 661 // type and, for a very short period of time, the klass and length 662 // fields will be inconsistent. This could cause a refinement 663 // thread to calculate the object size incorrectly. 664 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0); 665 666 // We will set up the first region as "starts humongous". This 667 // will also update the BOT covering all the regions to reflect 668 // that there is a single object that starts at the bottom of the 669 // first region. 670 first_hr->set_starts_humongous(new_top, new_end); 671 first_hr->set_allocation_context(context); 672 // Then, if there are any, we will set up the "continues 673 // humongous" regions. 674 HeapRegion* hr = NULL; 675 for (uint i = first + 1; i < last; ++i) { 676 hr = region_at(i); 677 hr->set_continues_humongous(first_hr); 678 hr->set_allocation_context(context); 679 } 680 // If we have "continues humongous" regions (hr != NULL), then the 681 // end of the last one should match new_end. 682 assert(hr == NULL || hr->end() == new_end, "sanity"); 683 684 // Up to this point no concurrent thread would have been able to 685 // do any scanning on any region in this series. All the top 686 // fields still point to bottom, so the intersection between 687 // [bottom,top] and [card_start,card_end] will be empty. Before we 688 // update the top fields, we'll do a storestore to make sure that 689 // no thread sees the update to top before the zeroing of the 690 // object header and the BOT initialization. 691 OrderAccess::storestore(); 692 693 // Now that the BOT and the object header have been initialized, 694 // we can update top of the "starts humongous" region. 695 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(), 696 "new_top should be in this region"); 697 first_hr->set_top(new_top); 698 if (_hr_printer.is_active()) { 699 HeapWord* bottom = first_hr->bottom(); 700 HeapWord* end = first_hr->orig_end(); 701 if ((first + 1) == last) { 702 // the series has a single humongous region 703 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top); 704 } else { 705 // the series has more than one humongous regions 706 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end); 707 } 708 } 709 710 // Now, we will update the top fields of the "continues humongous" 711 // regions. The reason we need to do this is that, otherwise, 712 // these regions would look empty and this will confuse parts of 713 // G1. For example, the code that looks for a consecutive number 714 // of empty regions will consider them empty and try to 715 // re-allocate them. We can extend is_empty() to also include 716 // !is_continues_humongous(), but it is easier to just update the top 717 // fields here. The way we set top for all regions (i.e., top == 718 // end for all regions but the last one, top == new_top for the 719 // last one) is actually used when we will free up the humongous 720 // region in free_humongous_region(). 721 hr = NULL; 722 for (uint i = first + 1; i < last; ++i) { 723 hr = region_at(i); 724 if ((i + 1) == last) { 725 // last continues humongous region 726 assert(hr->bottom() < new_top && new_top <= hr->end(), 727 "new_top should fall on this region"); 728 hr->set_top(new_top); 729 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top); 730 } else { 731 // not last one 732 assert(new_top > hr->end(), "new_top should be above this region"); 733 hr->set_top(hr->end()); 734 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end()); 735 } 736 } 737 // If we have continues humongous regions (hr != NULL), then the 738 // end of the last one should match new_end and its top should 739 // match new_top. 740 assert(hr == NULL || 741 (hr->end() == new_end && hr->top() == new_top), "sanity"); 742 check_bitmaps("Humongous Region Allocation", first_hr); 743 744 assert(first_hr->used() == word_size * HeapWordSize, "invariant"); 745 _allocator->increase_used(first_hr->used()); 746 _humongous_set.add(first_hr); 747 748 return new_obj; 749 } 750 751 // If could fit into free regions w/o expansion, try. 752 // Otherwise, if can expand, do so. 753 // Otherwise, if using ex regions might help, try with ex given back. 754 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) { 755 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 756 757 verify_region_sets_optional(); 758 759 uint first = G1_NO_HRM_INDEX; 760 uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords); 761 762 if (obj_regions == 1) { 763 // Only one region to allocate, try to use a fast path by directly allocating 764 // from the free lists. Do not try to expand here, we will potentially do that 765 // later. 766 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */); 767 if (hr != NULL) { 768 first = hr->hrm_index(); 769 } 770 } else { 771 // We can't allocate humongous regions spanning more than one region while 772 // cleanupComplete() is running, since some of the regions we find to be 773 // empty might not yet be added to the free list. It is not straightforward 774 // to know in which list they are on so that we can remove them. We only 775 // need to do this if we need to allocate more than one region to satisfy the 776 // current humongous allocation request. If we are only allocating one region 777 // we use the one-region region allocation code (see above), that already 778 // potentially waits for regions from the secondary free list. 779 wait_while_free_regions_coming(); 780 append_secondary_free_list_if_not_empty_with_lock(); 781 782 // Policy: Try only empty regions (i.e. already committed first). Maybe we 783 // are lucky enough to find some. 784 first = _hrm.find_contiguous_only_empty(obj_regions); 785 if (first != G1_NO_HRM_INDEX) { 786 _hrm.allocate_free_regions_starting_at(first, obj_regions); 787 } 788 } 789 790 if (first == G1_NO_HRM_INDEX) { 791 // Policy: We could not find enough regions for the humongous object in the 792 // free list. Look through the heap to find a mix of free and uncommitted regions. 793 // If so, try expansion. 794 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions); 795 if (first != G1_NO_HRM_INDEX) { 796 // We found something. Make sure these regions are committed, i.e. expand 797 // the heap. Alternatively we could do a defragmentation GC. 798 ergo_verbose1(ErgoHeapSizing, 799 "attempt heap expansion", 800 ergo_format_reason("humongous allocation request failed") 801 ergo_format_byte("allocation request"), 802 word_size * HeapWordSize); 803 804 _hrm.expand_at(first, obj_regions); 805 g1_policy()->record_new_heap_size(num_regions()); 806 807 #ifdef ASSERT 808 for (uint i = first; i < first + obj_regions; ++i) { 809 HeapRegion* hr = region_at(i); 810 assert(hr->is_free(), "sanity"); 811 assert(hr->is_empty(), "sanity"); 812 assert(is_on_master_free_list(hr), "sanity"); 813 } 814 #endif 815 _hrm.allocate_free_regions_starting_at(first, obj_regions); 816 } else { 817 // Policy: Potentially trigger a defragmentation GC. 818 } 819 } 820 821 HeapWord* result = NULL; 822 if (first != G1_NO_HRM_INDEX) { 823 result = humongous_obj_allocate_initialize_regions(first, obj_regions, 824 word_size, context); 825 assert(result != NULL, "it should always return a valid result"); 826 827 // A successful humongous object allocation changes the used space 828 // information of the old generation so we need to recalculate the 829 // sizes and update the jstat counters here. 830 g1mm()->update_sizes(); 831 } 832 833 verify_region_sets_optional(); 834 835 return result; 836 } 837 838 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) { 839 assert_heap_not_locked_and_not_at_safepoint(); 840 assert(!is_humongous(word_size), "we do not allow humongous TLABs"); 841 842 unsigned int dummy_gc_count_before; 843 int dummy_gclocker_retry_count = 0; 844 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count); 845 } 846 847 HeapWord* 848 G1CollectedHeap::mem_allocate(size_t word_size, 849 bool* gc_overhead_limit_was_exceeded) { 850 assert_heap_not_locked_and_not_at_safepoint(); 851 852 // Loop until the allocation is satisfied, or unsatisfied after GC. 853 for (int try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 854 unsigned int gc_count_before; 855 856 HeapWord* result = NULL; 857 if (!is_humongous(word_size)) { 858 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count); 859 } else { 860 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count); 861 } 862 if (result != NULL) { 863 return result; 864 } 865 866 // Create the garbage collection operation... 867 VM_G1CollectForAllocation op(gc_count_before, word_size); 868 op.set_allocation_context(AllocationContext::current()); 869 870 // ...and get the VM thread to execute it. 871 VMThread::execute(&op); 872 873 if (op.prologue_succeeded() && op.pause_succeeded()) { 874 // If the operation was successful we'll return the result even 875 // if it is NULL. If the allocation attempt failed immediately 876 // after a Full GC, it's unlikely we'll be able to allocate now. 877 HeapWord* result = op.result(); 878 if (result != NULL && !is_humongous(word_size)) { 879 // Allocations that take place on VM operations do not do any 880 // card dirtying and we have to do it here. We only have to do 881 // this for non-humongous allocations, though. 882 dirty_young_block(result, word_size); 883 } 884 return result; 885 } else { 886 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 887 return NULL; 888 } 889 assert(op.result() == NULL, 890 "the result should be NULL if the VM op did not succeed"); 891 } 892 893 // Give a warning if we seem to be looping forever. 894 if ((QueuedAllocationWarningCount > 0) && 895 (try_count % QueuedAllocationWarningCount == 0)) { 896 warning("G1CollectedHeap::mem_allocate retries %d times", try_count); 897 } 898 } 899 900 ShouldNotReachHere(); 901 return NULL; 902 } 903 904 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size, 905 AllocationContext_t context, 906 unsigned int *gc_count_before_ret, 907 int* gclocker_retry_count_ret) { 908 // Make sure you read the note in attempt_allocation_humongous(). 909 910 assert_heap_not_locked_and_not_at_safepoint(); 911 assert(!is_humongous(word_size), "attempt_allocation_slow() should not " 912 "be called for humongous allocation requests"); 913 914 // We should only get here after the first-level allocation attempt 915 // (attempt_allocation()) failed to allocate. 916 917 // We will loop until a) we manage to successfully perform the 918 // allocation or b) we successfully schedule a collection which 919 // fails to perform the allocation. b) is the only case when we'll 920 // return NULL. 921 HeapWord* result = NULL; 922 for (int try_count = 1; /* we'll return */; try_count += 1) { 923 bool should_try_gc; 924 unsigned int gc_count_before; 925 926 { 927 MutexLockerEx x(Heap_lock); 928 result = _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size, 929 false /* bot_updates */); 930 if (result != NULL) { 931 return result; 932 } 933 934 // If we reach here, attempt_allocation_locked() above failed to 935 // allocate a new region. So the mutator alloc region should be NULL. 936 assert(_allocator->mutator_alloc_region(context)->get() == NULL, "only way to get here"); 937 938 if (GC_locker::is_active_and_needs_gc()) { 939 if (g1_policy()->can_expand_young_list()) { 940 // No need for an ergo verbose message here, 941 // can_expand_young_list() does this when it returns true. 942 result = _allocator->mutator_alloc_region(context)->attempt_allocation_force(word_size, 943 false /* bot_updates */); 944 if (result != NULL) { 945 return result; 946 } 947 } 948 should_try_gc = false; 949 } else { 950 // The GCLocker may not be active but the GCLocker initiated 951 // GC may not yet have been performed (GCLocker::needs_gc() 952 // returns true). In this case we do not try this GC and 953 // wait until the GCLocker initiated GC is performed, and 954 // then retry the allocation. 955 if (GC_locker::needs_gc()) { 956 should_try_gc = false; 957 } else { 958 // Read the GC count while still holding the Heap_lock. 959 gc_count_before = total_collections(); 960 should_try_gc = true; 961 } 962 } 963 } 964 965 if (should_try_gc) { 966 bool succeeded; 967 result = do_collection_pause(word_size, gc_count_before, &succeeded, 968 GCCause::_g1_inc_collection_pause); 969 if (result != NULL) { 970 assert(succeeded, "only way to get back a non-NULL result"); 971 return result; 972 } 973 974 if (succeeded) { 975 // If we get here we successfully scheduled a collection which 976 // failed to allocate. No point in trying to allocate 977 // further. We'll just return NULL. 978 MutexLockerEx x(Heap_lock); 979 *gc_count_before_ret = total_collections(); 980 return NULL; 981 } 982 } else { 983 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { 984 MutexLockerEx x(Heap_lock); 985 *gc_count_before_ret = total_collections(); 986 return NULL; 987 } 988 // The GCLocker is either active or the GCLocker initiated 989 // GC has not yet been performed. Stall until it is and 990 // then retry the allocation. 991 GC_locker::stall_until_clear(); 992 (*gclocker_retry_count_ret) += 1; 993 } 994 995 // We can reach here if we were unsuccessful in scheduling a 996 // collection (because another thread beat us to it) or if we were 997 // stalled due to the GC locker. In either can we should retry the 998 // allocation attempt in case another thread successfully 999 // performed a collection and reclaimed enough space. We do the 1000 // first attempt (without holding the Heap_lock) here and the 1001 // follow-on attempt will be at the start of the next loop 1002 // iteration (after taking the Heap_lock). 1003 result = _allocator->mutator_alloc_region(context)->attempt_allocation(word_size, 1004 false /* bot_updates */); 1005 if (result != NULL) { 1006 return result; 1007 } 1008 1009 // Give a warning if we seem to be looping forever. 1010 if ((QueuedAllocationWarningCount > 0) && 1011 (try_count % QueuedAllocationWarningCount == 0)) { 1012 warning("G1CollectedHeap::attempt_allocation_slow() " 1013 "retries %d times", try_count); 1014 } 1015 } 1016 1017 ShouldNotReachHere(); 1018 return NULL; 1019 } 1020 1021 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size, 1022 unsigned int * gc_count_before_ret, 1023 int* gclocker_retry_count_ret) { 1024 // The structure of this method has a lot of similarities to 1025 // attempt_allocation_slow(). The reason these two were not merged 1026 // into a single one is that such a method would require several "if 1027 // allocation is not humongous do this, otherwise do that" 1028 // conditional paths which would obscure its flow. In fact, an early 1029 // version of this code did use a unified method which was harder to 1030 // follow and, as a result, it had subtle bugs that were hard to 1031 // track down. So keeping these two methods separate allows each to 1032 // be more readable. It will be good to keep these two in sync as 1033 // much as possible. 1034 1035 assert_heap_not_locked_and_not_at_safepoint(); 1036 assert(is_humongous(word_size), "attempt_allocation_humongous() " 1037 "should only be called for humongous allocations"); 1038 1039 // Humongous objects can exhaust the heap quickly, so we should check if we 1040 // need to start a marking cycle at each humongous object allocation. We do 1041 // the check before we do the actual allocation. The reason for doing it 1042 // before the allocation is that we avoid having to keep track of the newly 1043 // allocated memory while we do a GC. 1044 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation", 1045 word_size)) { 1046 collect(GCCause::_g1_humongous_allocation); 1047 } 1048 1049 // We will loop until a) we manage to successfully perform the 1050 // allocation or b) we successfully schedule a collection which 1051 // fails to perform the allocation. b) is the only case when we'll 1052 // return NULL. 1053 HeapWord* result = NULL; 1054 for (int try_count = 1; /* we'll return */; try_count += 1) { 1055 bool should_try_gc; 1056 unsigned int gc_count_before; 1057 1058 { 1059 MutexLockerEx x(Heap_lock); 1060 1061 // Given that humongous objects are not allocated in young 1062 // regions, we'll first try to do the allocation without doing a 1063 // collection hoping that there's enough space in the heap. 1064 result = humongous_obj_allocate(word_size, AllocationContext::current()); 1065 if (result != NULL) { 1066 return result; 1067 } 1068 1069 if (GC_locker::is_active_and_needs_gc()) { 1070 should_try_gc = false; 1071 } else { 1072 // The GCLocker may not be active but the GCLocker initiated 1073 // GC may not yet have been performed (GCLocker::needs_gc() 1074 // returns true). In this case we do not try this GC and 1075 // wait until the GCLocker initiated GC is performed, and 1076 // then retry the allocation. 1077 if (GC_locker::needs_gc()) { 1078 should_try_gc = false; 1079 } else { 1080 // Read the GC count while still holding the Heap_lock. 1081 gc_count_before = total_collections(); 1082 should_try_gc = true; 1083 } 1084 } 1085 } 1086 1087 if (should_try_gc) { 1088 // If we failed to allocate the humongous object, we should try to 1089 // do a collection pause (if we're allowed) in case it reclaims 1090 // enough space for the allocation to succeed after the pause. 1091 1092 bool succeeded; 1093 result = do_collection_pause(word_size, gc_count_before, &succeeded, 1094 GCCause::_g1_humongous_allocation); 1095 if (result != NULL) { 1096 assert(succeeded, "only way to get back a non-NULL result"); 1097 return result; 1098 } 1099 1100 if (succeeded) { 1101 // If we get here we successfully scheduled a collection which 1102 // failed to allocate. No point in trying to allocate 1103 // further. We'll just return NULL. 1104 MutexLockerEx x(Heap_lock); 1105 *gc_count_before_ret = total_collections(); 1106 return NULL; 1107 } 1108 } else { 1109 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { 1110 MutexLockerEx x(Heap_lock); 1111 *gc_count_before_ret = total_collections(); 1112 return NULL; 1113 } 1114 // The GCLocker is either active or the GCLocker initiated 1115 // GC has not yet been performed. Stall until it is and 1116 // then retry the allocation. 1117 GC_locker::stall_until_clear(); 1118 (*gclocker_retry_count_ret) += 1; 1119 } 1120 1121 // We can reach here if we were unsuccessful in scheduling a 1122 // collection (because another thread beat us to it) or if we were 1123 // stalled due to the GC locker. In either can we should retry the 1124 // allocation attempt in case another thread successfully 1125 // performed a collection and reclaimed enough space. Give a 1126 // warning if we seem to be looping forever. 1127 1128 if ((QueuedAllocationWarningCount > 0) && 1129 (try_count % QueuedAllocationWarningCount == 0)) { 1130 warning("G1CollectedHeap::attempt_allocation_humongous() " 1131 "retries %d times", try_count); 1132 } 1133 } 1134 1135 ShouldNotReachHere(); 1136 return NULL; 1137 } 1138 1139 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size, 1140 AllocationContext_t context, 1141 bool expect_null_mutator_alloc_region) { 1142 assert_at_safepoint(true /* should_be_vm_thread */); 1143 assert(_allocator->mutator_alloc_region(context)->get() == NULL || 1144 !expect_null_mutator_alloc_region, 1145 "the current alloc region was unexpectedly found to be non-NULL"); 1146 1147 if (!is_humongous(word_size)) { 1148 return _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size, 1149 false /* bot_updates */); 1150 } else { 1151 HeapWord* result = humongous_obj_allocate(word_size, context); 1152 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) { 1153 g1_policy()->set_initiate_conc_mark_if_possible(); 1154 } 1155 return result; 1156 } 1157 1158 ShouldNotReachHere(); 1159 } 1160 1161 class PostMCRemSetClearClosure: public HeapRegionClosure { 1162 G1CollectedHeap* _g1h; 1163 ModRefBarrierSet* _mr_bs; 1164 public: 1165 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) : 1166 _g1h(g1h), _mr_bs(mr_bs) {} 1167 1168 bool doHeapRegion(HeapRegion* r) { 1169 HeapRegionRemSet* hrrs = r->rem_set(); 1170 1171 if (r->is_continues_humongous()) { 1172 // We'll assert that the strong code root list and RSet is empty 1173 assert(hrrs->strong_code_roots_list_length() == 0, "sanity"); 1174 assert(hrrs->occupied() == 0, "RSet should be empty"); 1175 return false; 1176 } 1177 1178 _g1h->reset_gc_time_stamps(r); 1179 hrrs->clear(); 1180 // You might think here that we could clear just the cards 1181 // corresponding to the used region. But no: if we leave a dirty card 1182 // in a region we might allocate into, then it would prevent that card 1183 // from being enqueued, and cause it to be missed. 1184 // Re: the performance cost: we shouldn't be doing full GC anyway! 1185 _mr_bs->clear(MemRegion(r->bottom(), r->end())); 1186 1187 return false; 1188 } 1189 }; 1190 1191 void G1CollectedHeap::clear_rsets_post_compaction() { 1192 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set()); 1193 heap_region_iterate(&rs_clear); 1194 } 1195 1196 class RebuildRSOutOfRegionClosure: public HeapRegionClosure { 1197 G1CollectedHeap* _g1h; 1198 UpdateRSOopClosure _cl; 1199 int _worker_i; 1200 public: 1201 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) : 1202 _cl(g1->g1_rem_set(), worker_i), 1203 _worker_i(worker_i), 1204 _g1h(g1) 1205 { } 1206 1207 bool doHeapRegion(HeapRegion* r) { 1208 if (!r->is_continues_humongous()) { 1209 _cl.set_from(r); 1210 r->oop_iterate(&_cl); 1211 } 1212 return false; 1213 } 1214 }; 1215 1216 class ParRebuildRSTask: public AbstractGangTask { 1217 G1CollectedHeap* _g1; 1218 public: 1219 ParRebuildRSTask(G1CollectedHeap* g1) 1220 : AbstractGangTask("ParRebuildRSTask"), 1221 _g1(g1) 1222 { } 1223 1224 void work(uint worker_id) { 1225 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id); 1226 _g1->heap_region_par_iterate_chunked(&rebuild_rs, worker_id, 1227 _g1->workers()->active_workers(), 1228 HeapRegion::RebuildRSClaimValue); 1229 } 1230 }; 1231 1232 class PostCompactionPrinterClosure: public HeapRegionClosure { 1233 private: 1234 G1HRPrinter* _hr_printer; 1235 public: 1236 bool doHeapRegion(HeapRegion* hr) { 1237 assert(!hr->is_young(), "not expecting to find young regions"); 1238 if (hr->is_free()) { 1239 // We only generate output for non-empty regions. 1240 } else if (hr->is_starts_humongous()) { 1241 if (hr->region_num() == 1) { 1242 // single humongous region 1243 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous); 1244 } else { 1245 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous); 1246 } 1247 } else if (hr->is_continues_humongous()) { 1248 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous); 1249 } else if (hr->is_old()) { 1250 _hr_printer->post_compaction(hr, G1HRPrinter::Old); 1251 } else { 1252 ShouldNotReachHere(); 1253 } 1254 return false; 1255 } 1256 1257 PostCompactionPrinterClosure(G1HRPrinter* hr_printer) 1258 : _hr_printer(hr_printer) { } 1259 }; 1260 1261 void G1CollectedHeap::print_hrm_post_compaction() { 1262 PostCompactionPrinterClosure cl(hr_printer()); 1263 heap_region_iterate(&cl); 1264 } 1265 1266 bool G1CollectedHeap::do_collection(bool explicit_gc, 1267 bool clear_all_soft_refs, 1268 size_t word_size) { 1269 assert_at_safepoint(true /* should_be_vm_thread */); 1270 1271 if (GC_locker::check_active_before_gc()) { 1272 return false; 1273 } 1274 1275 STWGCTimer* gc_timer = G1MarkSweep::gc_timer(); 1276 gc_timer->register_gc_start(); 1277 1278 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer(); 1279 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start()); 1280 1281 SvcGCMarker sgcm(SvcGCMarker::FULL); 1282 ResourceMark rm; 1283 1284 print_heap_before_gc(); 1285 trace_heap_before_gc(gc_tracer); 1286 1287 size_t metadata_prev_used = MetaspaceAux::used_bytes(); 1288 1289 verify_region_sets_optional(); 1290 1291 const bool do_clear_all_soft_refs = clear_all_soft_refs || 1292 collector_policy()->should_clear_all_soft_refs(); 1293 1294 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy()); 1295 1296 { 1297 IsGCActiveMark x; 1298 1299 // Timing 1300 assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant"); 1301 gclog_or_tty->date_stamp(G1Log::fine() && PrintGCDateStamps); 1302 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty); 1303 1304 { 1305 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL, gc_tracer->gc_id()); 1306 TraceCollectorStats tcs(g1mm()->full_collection_counters()); 1307 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause()); 1308 1309 double start = os::elapsedTime(); 1310 g1_policy()->record_full_collection_start(); 1311 1312 // Note: When we have a more flexible GC logging framework that 1313 // allows us to add optional attributes to a GC log record we 1314 // could consider timing and reporting how long we wait in the 1315 // following two methods. 1316 wait_while_free_regions_coming(); 1317 // If we start the compaction before the CM threads finish 1318 // scanning the root regions we might trip them over as we'll 1319 // be moving objects / updating references. So let's wait until 1320 // they are done. By telling them to abort, they should complete 1321 // early. 1322 _cm->root_regions()->abort(); 1323 _cm->root_regions()->wait_until_scan_finished(); 1324 append_secondary_free_list_if_not_empty_with_lock(); 1325 1326 gc_prologue(true); 1327 increment_total_collections(true /* full gc */); 1328 increment_old_marking_cycles_started(); 1329 1330 assert(used() == recalculate_used(), "Should be equal"); 1331 1332 verify_before_gc(); 1333 1334 check_bitmaps("Full GC Start"); 1335 pre_full_gc_dump(gc_timer); 1336 1337 COMPILER2_PRESENT(DerivedPointerTable::clear()); 1338 1339 // Disable discovery and empty the discovered lists 1340 // for the CM ref processor. 1341 ref_processor_cm()->disable_discovery(); 1342 ref_processor_cm()->abandon_partial_discovery(); 1343 ref_processor_cm()->verify_no_references_recorded(); 1344 1345 // Abandon current iterations of concurrent marking and concurrent 1346 // refinement, if any are in progress. We have to do this before 1347 // wait_until_scan_finished() below. 1348 concurrent_mark()->abort(); 1349 1350 // Make sure we'll choose a new allocation region afterwards. 1351 _allocator->release_mutator_alloc_region(); 1352 _allocator->abandon_gc_alloc_regions(); 1353 g1_rem_set()->cleanupHRRS(); 1354 1355 // We should call this after we retire any currently active alloc 1356 // regions so that all the ALLOC / RETIRE events are generated 1357 // before the start GC event. 1358 _hr_printer.start_gc(true /* full */, (size_t) total_collections()); 1359 1360 // We may have added regions to the current incremental collection 1361 // set between the last GC or pause and now. We need to clear the 1362 // incremental collection set and then start rebuilding it afresh 1363 // after this full GC. 1364 abandon_collection_set(g1_policy()->inc_cset_head()); 1365 g1_policy()->clear_incremental_cset(); 1366 g1_policy()->stop_incremental_cset_building(); 1367 1368 tear_down_region_sets(false /* free_list_only */); 1369 g1_policy()->set_gcs_are_young(true); 1370 1371 // See the comments in g1CollectedHeap.hpp and 1372 // G1CollectedHeap::ref_processing_init() about 1373 // how reference processing currently works in G1. 1374 1375 // Temporarily make discovery by the STW ref processor single threaded (non-MT). 1376 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false); 1377 1378 // Temporarily clear the STW ref processor's _is_alive_non_header field. 1379 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL); 1380 1381 ref_processor_stw()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/); 1382 ref_processor_stw()->setup_policy(do_clear_all_soft_refs); 1383 1384 // Do collection work 1385 { 1386 HandleMark hm; // Discard invalid handles created during gc 1387 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs); 1388 } 1389 1390 assert(num_free_regions() == 0, "we should not have added any free regions"); 1391 rebuild_region_sets(false /* free_list_only */); 1392 1393 // Enqueue any discovered reference objects that have 1394 // not been removed from the discovered lists. 1395 ref_processor_stw()->enqueue_discovered_references(); 1396 1397 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 1398 1399 MemoryService::track_memory_usage(); 1400 1401 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 1402 ref_processor_stw()->verify_no_references_recorded(); 1403 1404 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 1405 ClassLoaderDataGraph::purge(); 1406 MetaspaceAux::verify_metrics(); 1407 1408 // Note: since we've just done a full GC, concurrent 1409 // marking is no longer active. Therefore we need not 1410 // re-enable reference discovery for the CM ref processor. 1411 // That will be done at the start of the next marking cycle. 1412 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition"); 1413 ref_processor_cm()->verify_no_references_recorded(); 1414 1415 reset_gc_time_stamp(); 1416 // Since everything potentially moved, we will clear all remembered 1417 // sets, and clear all cards. Later we will rebuild remembered 1418 // sets. We will also reset the GC time stamps of the regions. 1419 clear_rsets_post_compaction(); 1420 check_gc_time_stamps(); 1421 1422 // Resize the heap if necessary. 1423 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size); 1424 1425 if (_hr_printer.is_active()) { 1426 // We should do this after we potentially resize the heap so 1427 // that all the COMMIT / UNCOMMIT events are generated before 1428 // the end GC event. 1429 1430 print_hrm_post_compaction(); 1431 _hr_printer.end_gc(true /* full */, (size_t) total_collections()); 1432 } 1433 1434 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 1435 if (hot_card_cache->use_cache()) { 1436 hot_card_cache->reset_card_counts(); 1437 hot_card_cache->reset_hot_cache(); 1438 } 1439 1440 // Rebuild remembered sets of all regions. 1441 if (G1CollectedHeap::use_parallel_gc_threads()) { 1442 uint n_workers = 1443 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 1444 workers()->active_workers(), 1445 Threads::number_of_non_daemon_threads()); 1446 assert(UseDynamicNumberOfGCThreads || 1447 n_workers == workers()->total_workers(), 1448 "If not dynamic should be using all the workers"); 1449 workers()->set_active_workers(n_workers); 1450 // Set parallel threads in the heap (_n_par_threads) only 1451 // before a parallel phase and always reset it to 0 after 1452 // the phase so that the number of parallel threads does 1453 // no get carried forward to a serial phase where there 1454 // may be code that is "possibly_parallel". 1455 set_par_threads(n_workers); 1456 1457 ParRebuildRSTask rebuild_rs_task(this); 1458 assert(check_heap_region_claim_values( 1459 HeapRegion::InitialClaimValue), "sanity check"); 1460 assert(UseDynamicNumberOfGCThreads || 1461 workers()->active_workers() == workers()->total_workers(), 1462 "Unless dynamic should use total workers"); 1463 // Use the most recent number of active workers 1464 assert(workers()->active_workers() > 0, 1465 "Active workers not properly set"); 1466 set_par_threads(workers()->active_workers()); 1467 workers()->run_task(&rebuild_rs_task); 1468 set_par_threads(0); 1469 assert(check_heap_region_claim_values( 1470 HeapRegion::RebuildRSClaimValue), "sanity check"); 1471 reset_heap_region_claim_values(); 1472 } else { 1473 RebuildRSOutOfRegionClosure rebuild_rs(this); 1474 heap_region_iterate(&rebuild_rs); 1475 } 1476 1477 // Rebuild the strong code root lists for each region 1478 rebuild_strong_code_roots(); 1479 1480 if (true) { // FIXME 1481 MetaspaceGC::compute_new_size(); 1482 } 1483 1484 #ifdef TRACESPINNING 1485 ParallelTaskTerminator::print_termination_counts(); 1486 #endif 1487 1488 // Discard all rset updates 1489 JavaThread::dirty_card_queue_set().abandon_logs(); 1490 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty"); 1491 1492 _young_list->reset_sampled_info(); 1493 // At this point there should be no regions in the 1494 // entire heap tagged as young. 1495 assert(check_young_list_empty(true /* check_heap */), 1496 "young list should be empty at this point"); 1497 1498 // Update the number of full collections that have been completed. 1499 increment_old_marking_cycles_completed(false /* concurrent */); 1500 1501 _hrm.verify_optional(); 1502 verify_region_sets_optional(); 1503 1504 verify_after_gc(); 1505 1506 // Clear the previous marking bitmap, if needed for bitmap verification. 1507 // Note we cannot do this when we clear the next marking bitmap in 1508 // ConcurrentMark::abort() above since VerifyDuringGC verifies the 1509 // objects marked during a full GC against the previous bitmap. 1510 // But we need to clear it before calling check_bitmaps below since 1511 // the full GC has compacted objects and updated TAMS but not updated 1512 // the prev bitmap. 1513 if (G1VerifyBitmaps) { 1514 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll(); 1515 } 1516 check_bitmaps("Full GC End"); 1517 1518 // Start a new incremental collection set for the next pause 1519 assert(g1_policy()->collection_set() == NULL, "must be"); 1520 g1_policy()->start_incremental_cset_building(); 1521 1522 clear_cset_fast_test(); 1523 1524 _allocator->init_mutator_alloc_region(); 1525 1526 double end = os::elapsedTime(); 1527 g1_policy()->record_full_collection_end(); 1528 1529 if (G1Log::fine()) { 1530 g1_policy()->print_heap_transition(); 1531 } 1532 1533 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 1534 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 1535 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 1536 // before any GC notifications are raised. 1537 g1mm()->update_sizes(); 1538 1539 gc_epilogue(true); 1540 } 1541 1542 if (G1Log::finer()) { 1543 g1_policy()->print_detailed_heap_transition(true /* full */); 1544 } 1545 1546 print_heap_after_gc(); 1547 trace_heap_after_gc(gc_tracer); 1548 1549 post_full_gc_dump(gc_timer); 1550 1551 gc_timer->register_gc_end(); 1552 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions()); 1553 } 1554 1555 return true; 1556 } 1557 1558 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) { 1559 // do_collection() will return whether it succeeded in performing 1560 // the GC. Currently, there is no facility on the 1561 // do_full_collection() API to notify the caller than the collection 1562 // did not succeed (e.g., because it was locked out by the GC 1563 // locker). So, right now, we'll ignore the return value. 1564 bool dummy = do_collection(true, /* explicit_gc */ 1565 clear_all_soft_refs, 1566 0 /* word_size */); 1567 } 1568 1569 // This code is mostly copied from TenuredGeneration. 1570 void 1571 G1CollectedHeap:: 1572 resize_if_necessary_after_full_collection(size_t word_size) { 1573 // Include the current allocation, if any, and bytes that will be 1574 // pre-allocated to support collections, as "used". 1575 const size_t used_after_gc = used(); 1576 const size_t capacity_after_gc = capacity(); 1577 const size_t free_after_gc = capacity_after_gc - used_after_gc; 1578 1579 // This is enforced in arguments.cpp. 1580 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, 1581 "otherwise the code below doesn't make sense"); 1582 1583 // We don't have floating point command-line arguments 1584 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0; 1585 const double maximum_used_percentage = 1.0 - minimum_free_percentage; 1586 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0; 1587 const double minimum_used_percentage = 1.0 - maximum_free_percentage; 1588 1589 const size_t min_heap_size = collector_policy()->min_heap_byte_size(); 1590 const size_t max_heap_size = collector_policy()->max_heap_byte_size(); 1591 1592 // We have to be careful here as these two calculations can overflow 1593 // 32-bit size_t's. 1594 double used_after_gc_d = (double) used_after_gc; 1595 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage; 1596 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage; 1597 1598 // Let's make sure that they are both under the max heap size, which 1599 // by default will make them fit into a size_t. 1600 double desired_capacity_upper_bound = (double) max_heap_size; 1601 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d, 1602 desired_capacity_upper_bound); 1603 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d, 1604 desired_capacity_upper_bound); 1605 1606 // We can now safely turn them into size_t's. 1607 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d; 1608 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d; 1609 1610 // This assert only makes sense here, before we adjust them 1611 // with respect to the min and max heap size. 1612 assert(minimum_desired_capacity <= maximum_desired_capacity, 1613 err_msg("minimum_desired_capacity = "SIZE_FORMAT", " 1614 "maximum_desired_capacity = "SIZE_FORMAT, 1615 minimum_desired_capacity, maximum_desired_capacity)); 1616 1617 // Should not be greater than the heap max size. No need to adjust 1618 // it with respect to the heap min size as it's a lower bound (i.e., 1619 // we'll try to make the capacity larger than it, not smaller). 1620 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size); 1621 // Should not be less than the heap min size. No need to adjust it 1622 // with respect to the heap max size as it's an upper bound (i.e., 1623 // we'll try to make the capacity smaller than it, not greater). 1624 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size); 1625 1626 if (capacity_after_gc < minimum_desired_capacity) { 1627 // Don't expand unless it's significant 1628 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc; 1629 ergo_verbose4(ErgoHeapSizing, 1630 "attempt heap expansion", 1631 ergo_format_reason("capacity lower than " 1632 "min desired capacity after Full GC") 1633 ergo_format_byte("capacity") 1634 ergo_format_byte("occupancy") 1635 ergo_format_byte_perc("min desired capacity"), 1636 capacity_after_gc, used_after_gc, 1637 minimum_desired_capacity, (double) MinHeapFreeRatio); 1638 expand(expand_bytes); 1639 1640 // No expansion, now see if we want to shrink 1641 } else if (capacity_after_gc > maximum_desired_capacity) { 1642 // Capacity too large, compute shrinking size 1643 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity; 1644 ergo_verbose4(ErgoHeapSizing, 1645 "attempt heap shrinking", 1646 ergo_format_reason("capacity higher than " 1647 "max desired capacity after Full GC") 1648 ergo_format_byte("capacity") 1649 ergo_format_byte("occupancy") 1650 ergo_format_byte_perc("max desired capacity"), 1651 capacity_after_gc, used_after_gc, 1652 maximum_desired_capacity, (double) MaxHeapFreeRatio); 1653 shrink(shrink_bytes); 1654 } 1655 } 1656 1657 1658 HeapWord* 1659 G1CollectedHeap::satisfy_failed_allocation(size_t word_size, 1660 AllocationContext_t context, 1661 bool* succeeded) { 1662 assert_at_safepoint(true /* should_be_vm_thread */); 1663 1664 *succeeded = true; 1665 // Let's attempt the allocation first. 1666 HeapWord* result = 1667 attempt_allocation_at_safepoint(word_size, 1668 context, 1669 false /* expect_null_mutator_alloc_region */); 1670 if (result != NULL) { 1671 assert(*succeeded, "sanity"); 1672 return result; 1673 } 1674 1675 // In a G1 heap, we're supposed to keep allocation from failing by 1676 // incremental pauses. Therefore, at least for now, we'll favor 1677 // expansion over collection. (This might change in the future if we can 1678 // do something smarter than full collection to satisfy a failed alloc.) 1679 result = expand_and_allocate(word_size, context); 1680 if (result != NULL) { 1681 assert(*succeeded, "sanity"); 1682 return result; 1683 } 1684 1685 // Expansion didn't work, we'll try to do a Full GC. 1686 bool gc_succeeded = do_collection(false, /* explicit_gc */ 1687 false, /* clear_all_soft_refs */ 1688 word_size); 1689 if (!gc_succeeded) { 1690 *succeeded = false; 1691 return NULL; 1692 } 1693 1694 // Retry the allocation 1695 result = attempt_allocation_at_safepoint(word_size, 1696 context, 1697 true /* expect_null_mutator_alloc_region */); 1698 if (result != NULL) { 1699 assert(*succeeded, "sanity"); 1700 return result; 1701 } 1702 1703 // Then, try a Full GC that will collect all soft references. 1704 gc_succeeded = do_collection(false, /* explicit_gc */ 1705 true, /* clear_all_soft_refs */ 1706 word_size); 1707 if (!gc_succeeded) { 1708 *succeeded = false; 1709 return NULL; 1710 } 1711 1712 // Retry the allocation once more 1713 result = attempt_allocation_at_safepoint(word_size, 1714 context, 1715 true /* expect_null_mutator_alloc_region */); 1716 if (result != NULL) { 1717 assert(*succeeded, "sanity"); 1718 return result; 1719 } 1720 1721 assert(!collector_policy()->should_clear_all_soft_refs(), 1722 "Flag should have been handled and cleared prior to this point"); 1723 1724 // What else? We might try synchronous finalization later. If the total 1725 // space available is large enough for the allocation, then a more 1726 // complete compaction phase than we've tried so far might be 1727 // appropriate. 1728 assert(*succeeded, "sanity"); 1729 return NULL; 1730 } 1731 1732 // Attempting to expand the heap sufficiently 1733 // to support an allocation of the given "word_size". If 1734 // successful, perform the allocation and return the address of the 1735 // allocated block, or else "NULL". 1736 1737 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) { 1738 assert_at_safepoint(true /* should_be_vm_thread */); 1739 1740 verify_region_sets_optional(); 1741 1742 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes); 1743 ergo_verbose1(ErgoHeapSizing, 1744 "attempt heap expansion", 1745 ergo_format_reason("allocation request failed") 1746 ergo_format_byte("allocation request"), 1747 word_size * HeapWordSize); 1748 if (expand(expand_bytes)) { 1749 _hrm.verify_optional(); 1750 verify_region_sets_optional(); 1751 return attempt_allocation_at_safepoint(word_size, 1752 context, 1753 false /* expect_null_mutator_alloc_region */); 1754 } 1755 return NULL; 1756 } 1757 1758 bool G1CollectedHeap::expand(size_t expand_bytes) { 1759 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); 1760 aligned_expand_bytes = align_size_up(aligned_expand_bytes, 1761 HeapRegion::GrainBytes); 1762 ergo_verbose2(ErgoHeapSizing, 1763 "expand the heap", 1764 ergo_format_byte("requested expansion amount") 1765 ergo_format_byte("attempted expansion amount"), 1766 expand_bytes, aligned_expand_bytes); 1767 1768 if (is_maximal_no_gc()) { 1769 ergo_verbose0(ErgoHeapSizing, 1770 "did not expand the heap", 1771 ergo_format_reason("heap already fully expanded")); 1772 return false; 1773 } 1774 1775 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes); 1776 assert(regions_to_expand > 0, "Must expand by at least one region"); 1777 1778 uint expanded_by = _hrm.expand_by(regions_to_expand); 1779 1780 if (expanded_by > 0) { 1781 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes; 1782 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition"); 1783 g1_policy()->record_new_heap_size(num_regions()); 1784 } else { 1785 ergo_verbose0(ErgoHeapSizing, 1786 "did not expand the heap", 1787 ergo_format_reason("heap expansion operation failed")); 1788 // The expansion of the virtual storage space was unsuccessful. 1789 // Let's see if it was because we ran out of swap. 1790 if (G1ExitOnExpansionFailure && 1791 _hrm.available() >= regions_to_expand) { 1792 // We had head room... 1793 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion"); 1794 } 1795 } 1796 return regions_to_expand > 0; 1797 } 1798 1799 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) { 1800 size_t aligned_shrink_bytes = 1801 ReservedSpace::page_align_size_down(shrink_bytes); 1802 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes, 1803 HeapRegion::GrainBytes); 1804 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes); 1805 1806 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove); 1807 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes; 1808 1809 ergo_verbose3(ErgoHeapSizing, 1810 "shrink the heap", 1811 ergo_format_byte("requested shrinking amount") 1812 ergo_format_byte("aligned shrinking amount") 1813 ergo_format_byte("attempted shrinking amount"), 1814 shrink_bytes, aligned_shrink_bytes, shrunk_bytes); 1815 if (num_regions_removed > 0) { 1816 g1_policy()->record_new_heap_size(num_regions()); 1817 } else { 1818 ergo_verbose0(ErgoHeapSizing, 1819 "did not shrink the heap", 1820 ergo_format_reason("heap shrinking operation failed")); 1821 } 1822 } 1823 1824 void G1CollectedHeap::shrink(size_t shrink_bytes) { 1825 verify_region_sets_optional(); 1826 1827 // We should only reach here at the end of a Full GC which means we 1828 // should not not be holding to any GC alloc regions. The method 1829 // below will make sure of that and do any remaining clean up. 1830 _allocator->abandon_gc_alloc_regions(); 1831 1832 // Instead of tearing down / rebuilding the free lists here, we 1833 // could instead use the remove_all_pending() method on free_list to 1834 // remove only the ones that we need to remove. 1835 tear_down_region_sets(true /* free_list_only */); 1836 shrink_helper(shrink_bytes); 1837 rebuild_region_sets(true /* free_list_only */); 1838 1839 _hrm.verify_optional(); 1840 verify_region_sets_optional(); 1841 } 1842 1843 // Public methods. 1844 1845 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away 1846 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list 1847 #endif // _MSC_VER 1848 1849 1850 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) : 1851 SharedHeap(policy_), 1852 _g1_policy(policy_), 1853 _dirty_card_queue_set(false), 1854 _into_cset_dirty_card_queue_set(false), 1855 _is_alive_closure_cm(this), 1856 _is_alive_closure_stw(this), 1857 _ref_processor_cm(NULL), 1858 _ref_processor_stw(NULL), 1859 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)), 1860 _bot_shared(NULL), 1861 _evac_failure_scan_stack(NULL), 1862 _mark_in_progress(false), 1863 _cg1r(NULL), 1864 _g1mm(NULL), 1865 _refine_cte_cl(NULL), 1866 _full_collection(false), 1867 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()), 1868 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()), 1869 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()), 1870 _humongous_is_live(), 1871 _has_humongous_reclaim_candidates(false), 1872 _free_regions_coming(false), 1873 _young_list(new YoungList(this)), 1874 _gc_time_stamp(0), 1875 _survivor_plab_stats(YoungPLABSize, PLABWeight), 1876 _old_plab_stats(OldPLABSize, PLABWeight), 1877 _expand_heap_after_alloc_failure(true), 1878 _surviving_young_words(NULL), 1879 _old_marking_cycles_started(0), 1880 _old_marking_cycles_completed(0), 1881 _concurrent_cycle_started(false), 1882 _heap_summary_sent(false), 1883 _in_cset_fast_test(), 1884 _dirty_cards_region_list(NULL), 1885 _worker_cset_start_region(NULL), 1886 _worker_cset_start_region_time_stamp(NULL), 1887 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()), 1888 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()), 1889 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()), 1890 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) { 1891 1892 _g1h = this; 1893 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) { 1894 vm_exit_during_initialization("Failed necessary allocation."); 1895 } 1896 1897 _allocator = G1Allocator::create_allocator(_g1h); 1898 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2; 1899 1900 int n_queues = MAX2((int)ParallelGCThreads, 1); 1901 _task_queues = new RefToScanQueueSet(n_queues); 1902 1903 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets(); 1904 assert(n_rem_sets > 0, "Invariant."); 1905 1906 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC); 1907 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(unsigned int, n_queues, mtGC); 1908 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC); 1909 1910 for (int i = 0; i < n_queues; i++) { 1911 RefToScanQueue* q = new RefToScanQueue(); 1912 q->initialize(); 1913 _task_queues->register_queue(i, q); 1914 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo(); 1915 } 1916 clear_cset_start_regions(); 1917 1918 // Initialize the G1EvacuationFailureALot counters and flags. 1919 NOT_PRODUCT(reset_evacuation_should_fail();) 1920 1921 guarantee(_task_queues != NULL, "task_queues allocation failure."); 1922 } 1923 1924 jint G1CollectedHeap::initialize() { 1925 CollectedHeap::pre_initialize(); 1926 os::enable_vtime(); 1927 1928 G1Log::init(); 1929 1930 // Necessary to satisfy locking discipline assertions. 1931 1932 MutexLocker x(Heap_lock); 1933 1934 // We have to initialize the printer before committing the heap, as 1935 // it will be used then. 1936 _hr_printer.set_active(G1PrintHeapRegions); 1937 1938 // While there are no constraints in the GC code that HeapWordSize 1939 // be any particular value, there are multiple other areas in the 1940 // system which believe this to be true (e.g. oop->object_size in some 1941 // cases incorrectly returns the size in wordSize units rather than 1942 // HeapWordSize). 1943 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 1944 1945 size_t init_byte_size = collector_policy()->initial_heap_byte_size(); 1946 size_t max_byte_size = collector_policy()->max_heap_byte_size(); 1947 size_t heap_alignment = collector_policy()->heap_alignment(); 1948 1949 // Ensure that the sizes are properly aligned. 1950 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1951 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1952 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap"); 1953 1954 _refine_cte_cl = new RefineCardTableEntryClosure(); 1955 1956 _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl); 1957 1958 // Reserve the maximum. 1959 1960 // When compressed oops are enabled, the preferred heap base 1961 // is calculated by subtracting the requested size from the 1962 // 32Gb boundary and using the result as the base address for 1963 // heap reservation. If the requested size is not aligned to 1964 // HeapRegion::GrainBytes (i.e. the alignment that is passed 1965 // into the ReservedHeapSpace constructor) then the actual 1966 // base of the reserved heap may end up differing from the 1967 // address that was requested (i.e. the preferred heap base). 1968 // If this happens then we could end up using a non-optimal 1969 // compressed oops mode. 1970 1971 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size, 1972 heap_alignment); 1973 1974 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size())); 1975 1976 // Create the gen rem set (and barrier set) for the entire reserved region. 1977 _rem_set = collector_policy()->create_rem_set(reserved_region(), 2); 1978 set_barrier_set(rem_set()->bs()); 1979 if (!barrier_set()->is_a(BarrierSet::G1SATBCTLogging)) { 1980 vm_exit_during_initialization("G1 requires a G1SATBLoggingCardTableModRefBS"); 1981 return JNI_ENOMEM; 1982 } 1983 1984 // Also create a G1 rem set. 1985 _g1_rem_set = new G1RemSet(this, g1_barrier_set()); 1986 1987 // Carve out the G1 part of the heap. 1988 1989 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size); 1990 G1RegionToSpaceMapper* heap_storage = 1991 G1RegionToSpaceMapper::create_mapper(g1_rs, 1992 UseLargePages ? os::large_page_size() : os::vm_page_size(), 1993 HeapRegion::GrainBytes, 1994 1, 1995 mtJavaHeap); 1996 heap_storage->set_mapping_changed_listener(&_listener); 1997 1998 // Reserve space for the block offset table. We do not support automatic uncommit 1999 // for the card table at this time. BOT only. 2000 ReservedSpace bot_rs(G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize)); 2001 G1RegionToSpaceMapper* bot_storage = 2002 G1RegionToSpaceMapper::create_mapper(bot_rs, 2003 os::vm_page_size(), 2004 HeapRegion::GrainBytes, 2005 G1BlockOffsetSharedArray::N_bytes, 2006 mtGC); 2007 2008 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize)); 2009 G1RegionToSpaceMapper* cardtable_storage = 2010 G1RegionToSpaceMapper::create_mapper(cardtable_rs, 2011 os::vm_page_size(), 2012 HeapRegion::GrainBytes, 2013 G1BlockOffsetSharedArray::N_bytes, 2014 mtGC); 2015 2016 // Reserve space for the card counts table. 2017 ReservedSpace card_counts_rs(G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize)); 2018 G1RegionToSpaceMapper* card_counts_storage = 2019 G1RegionToSpaceMapper::create_mapper(card_counts_rs, 2020 os::vm_page_size(), 2021 HeapRegion::GrainBytes, 2022 G1BlockOffsetSharedArray::N_bytes, 2023 mtGC); 2024 2025 // Reserve space for prev and next bitmap. 2026 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size()); 2027 2028 ReservedSpace prev_bitmap_rs(ReservedSpace::allocation_align_size_up(bitmap_size)); 2029 G1RegionToSpaceMapper* prev_bitmap_storage = 2030 G1RegionToSpaceMapper::create_mapper(prev_bitmap_rs, 2031 os::vm_page_size(), 2032 HeapRegion::GrainBytes, 2033 CMBitMap::mark_distance(), 2034 mtGC); 2035 2036 ReservedSpace next_bitmap_rs(ReservedSpace::allocation_align_size_up(bitmap_size)); 2037 G1RegionToSpaceMapper* next_bitmap_storage = 2038 G1RegionToSpaceMapper::create_mapper(next_bitmap_rs, 2039 os::vm_page_size(), 2040 HeapRegion::GrainBytes, 2041 CMBitMap::mark_distance(), 2042 mtGC); 2043 2044 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage); 2045 g1_barrier_set()->initialize(cardtable_storage); 2046 // Do later initialization work for concurrent refinement. 2047 _cg1r->init(card_counts_storage); 2048 2049 // 6843694 - ensure that the maximum region index can fit 2050 // in the remembered set structures. 2051 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; 2052 guarantee((max_regions() - 1) <= max_region_idx, "too many regions"); 2053 2054 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; 2055 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); 2056 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region, 2057 "too many cards per region"); 2058 2059 FreeRegionList::set_unrealistically_long_length(max_regions() + 1); 2060 2061 _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage); 2062 2063 _g1h = this; 2064 2065 _in_cset_fast_test.initialize(_hrm.reserved().start(), _hrm.reserved().end(), HeapRegion::GrainBytes); 2066 _humongous_is_live.initialize(_hrm.reserved().start(), _hrm.reserved().end(), HeapRegion::GrainBytes); 2067 2068 // Create the ConcurrentMark data structure and thread. 2069 // (Must do this late, so that "max_regions" is defined.) 2070 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage); 2071 if (_cm == NULL || !_cm->completed_initialization()) { 2072 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark"); 2073 return JNI_ENOMEM; 2074 } 2075 _cmThread = _cm->cmThread(); 2076 2077 // Initialize the from_card cache structure of HeapRegionRemSet. 2078 HeapRegionRemSet::init_heap(max_regions()); 2079 2080 // Now expand into the initial heap size. 2081 if (!expand(init_byte_size)) { 2082 vm_shutdown_during_initialization("Failed to allocate initial heap."); 2083 return JNI_ENOMEM; 2084 } 2085 2086 // Perform any initialization actions delegated to the policy. 2087 g1_policy()->init(); 2088 2089 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon, 2090 SATB_Q_FL_lock, 2091 G1SATBProcessCompletedThreshold, 2092 Shared_SATB_Q_lock); 2093 2094 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl, 2095 DirtyCardQ_CBL_mon, 2096 DirtyCardQ_FL_lock, 2097 concurrent_g1_refine()->yellow_zone(), 2098 concurrent_g1_refine()->red_zone(), 2099 Shared_DirtyCardQ_lock); 2100 2101 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code 2102 DirtyCardQ_CBL_mon, 2103 DirtyCardQ_FL_lock, 2104 -1, // never trigger processing 2105 -1, // no limit on length 2106 Shared_DirtyCardQ_lock, 2107 &JavaThread::dirty_card_queue_set()); 2108 2109 // Initialize the card queue set used to hold cards containing 2110 // references into the collection set. 2111 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code 2112 DirtyCardQ_CBL_mon, 2113 DirtyCardQ_FL_lock, 2114 -1, // never trigger processing 2115 -1, // no limit on length 2116 Shared_DirtyCardQ_lock, 2117 &JavaThread::dirty_card_queue_set()); 2118 2119 // In case we're keeping closure specialization stats, initialize those 2120 // counts and that mechanism. 2121 SpecializationStats::clear(); 2122 2123 // Here we allocate the dummy HeapRegion that is required by the 2124 // G1AllocRegion class. 2125 HeapRegion* dummy_region = _hrm.get_dummy_region(); 2126 2127 // We'll re-use the same region whether the alloc region will 2128 // require BOT updates or not and, if it doesn't, then a non-young 2129 // region will complain that it cannot support allocations without 2130 // BOT updates. So we'll tag the dummy region as eden to avoid that. 2131 dummy_region->set_eden(); 2132 // Make sure it's full. 2133 dummy_region->set_top(dummy_region->end()); 2134 G1AllocRegion::setup(this, dummy_region); 2135 2136 _allocator->init_mutator_alloc_region(); 2137 2138 // Do create of the monitoring and management support so that 2139 // values in the heap have been properly initialized. 2140 _g1mm = new G1MonitoringSupport(this); 2141 2142 G1StringDedup::initialize(); 2143 2144 return JNI_OK; 2145 } 2146 2147 void G1CollectedHeap::stop() { 2148 // Stop all concurrent threads. We do this to make sure these threads 2149 // do not continue to execute and access resources (e.g. gclog_or_tty) 2150 // that are destroyed during shutdown. 2151 _cg1r->stop(); 2152 _cmThread->stop(); 2153 if (G1StringDedup::is_enabled()) { 2154 G1StringDedup::stop(); 2155 } 2156 } 2157 2158 void G1CollectedHeap::clear_humongous_is_live_table() { 2159 guarantee(G1ReclaimDeadHumongousObjectsAtYoungGC, "Should only be called if true"); 2160 _humongous_is_live.clear(); 2161 } 2162 2163 size_t G1CollectedHeap::conservative_max_heap_alignment() { 2164 return HeapRegion::max_region_size(); 2165 } 2166 2167 void G1CollectedHeap::ref_processing_init() { 2168 // Reference processing in G1 currently works as follows: 2169 // 2170 // * There are two reference processor instances. One is 2171 // used to record and process discovered references 2172 // during concurrent marking; the other is used to 2173 // record and process references during STW pauses 2174 // (both full and incremental). 2175 // * Both ref processors need to 'span' the entire heap as 2176 // the regions in the collection set may be dotted around. 2177 // 2178 // * For the concurrent marking ref processor: 2179 // * Reference discovery is enabled at initial marking. 2180 // * Reference discovery is disabled and the discovered 2181 // references processed etc during remarking. 2182 // * Reference discovery is MT (see below). 2183 // * Reference discovery requires a barrier (see below). 2184 // * Reference processing may or may not be MT 2185 // (depending on the value of ParallelRefProcEnabled 2186 // and ParallelGCThreads). 2187 // * A full GC disables reference discovery by the CM 2188 // ref processor and abandons any entries on it's 2189 // discovered lists. 2190 // 2191 // * For the STW processor: 2192 // * Non MT discovery is enabled at the start of a full GC. 2193 // * Processing and enqueueing during a full GC is non-MT. 2194 // * During a full GC, references are processed after marking. 2195 // 2196 // * Discovery (may or may not be MT) is enabled at the start 2197 // of an incremental evacuation pause. 2198 // * References are processed near the end of a STW evacuation pause. 2199 // * For both types of GC: 2200 // * Discovery is atomic - i.e. not concurrent. 2201 // * Reference discovery will not need a barrier. 2202 2203 SharedHeap::ref_processing_init(); 2204 MemRegion mr = reserved_region(); 2205 2206 // Concurrent Mark ref processor 2207 _ref_processor_cm = 2208 new ReferenceProcessor(mr, // span 2209 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2210 // mt processing 2211 (int) ParallelGCThreads, 2212 // degree of mt processing 2213 (ParallelGCThreads > 1) || (ConcGCThreads > 1), 2214 // mt discovery 2215 (int) MAX2(ParallelGCThreads, ConcGCThreads), 2216 // degree of mt discovery 2217 false, 2218 // Reference discovery is not atomic 2219 &_is_alive_closure_cm); 2220 // is alive closure 2221 // (for efficiency/performance) 2222 2223 // STW ref processor 2224 _ref_processor_stw = 2225 new ReferenceProcessor(mr, // span 2226 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2227 // mt processing 2228 MAX2((int)ParallelGCThreads, 1), 2229 // degree of mt processing 2230 (ParallelGCThreads > 1), 2231 // mt discovery 2232 MAX2((int)ParallelGCThreads, 1), 2233 // degree of mt discovery 2234 true, 2235 // Reference discovery is atomic 2236 &_is_alive_closure_stw); 2237 // is alive closure 2238 // (for efficiency/performance) 2239 } 2240 2241 size_t G1CollectedHeap::capacity() const { 2242 return _hrm.length() * HeapRegion::GrainBytes; 2243 } 2244 2245 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) { 2246 assert(!hr->is_continues_humongous(), "pre-condition"); 2247 hr->reset_gc_time_stamp(); 2248 if (hr->is_starts_humongous()) { 2249 uint first_index = hr->hrm_index() + 1; 2250 uint last_index = hr->last_hc_index(); 2251 for (uint i = first_index; i < last_index; i += 1) { 2252 HeapRegion* chr = region_at(i); 2253 assert(chr->is_continues_humongous(), "sanity"); 2254 chr->reset_gc_time_stamp(); 2255 } 2256 } 2257 } 2258 2259 #ifndef PRODUCT 2260 class CheckGCTimeStampsHRClosure : public HeapRegionClosure { 2261 private: 2262 unsigned _gc_time_stamp; 2263 bool _failures; 2264 2265 public: 2266 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) : 2267 _gc_time_stamp(gc_time_stamp), _failures(false) { } 2268 2269 virtual bool doHeapRegion(HeapRegion* hr) { 2270 unsigned region_gc_time_stamp = hr->get_gc_time_stamp(); 2271 if (_gc_time_stamp != region_gc_time_stamp) { 2272 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, " 2273 "expected %d", HR_FORMAT_PARAMS(hr), 2274 region_gc_time_stamp, _gc_time_stamp); 2275 _failures = true; 2276 } 2277 return false; 2278 } 2279 2280 bool failures() { return _failures; } 2281 }; 2282 2283 void G1CollectedHeap::check_gc_time_stamps() { 2284 CheckGCTimeStampsHRClosure cl(_gc_time_stamp); 2285 heap_region_iterate(&cl); 2286 guarantee(!cl.failures(), "all GC time stamps should have been reset"); 2287 } 2288 #endif // PRODUCT 2289 2290 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, 2291 DirtyCardQueue* into_cset_dcq, 2292 bool concurrent, 2293 uint worker_i) { 2294 // Clean cards in the hot card cache 2295 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 2296 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq); 2297 2298 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 2299 int n_completed_buffers = 0; 2300 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) { 2301 n_completed_buffers++; 2302 } 2303 g1_policy()->phase_times()->record_update_rs_processed_buffers(worker_i, n_completed_buffers); 2304 dcqs.clear_n_completed_buffers(); 2305 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!"); 2306 } 2307 2308 2309 // Computes the sum of the storage used by the various regions. 2310 size_t G1CollectedHeap::used() const { 2311 return _allocator->used(); 2312 } 2313 2314 size_t G1CollectedHeap::used_unlocked() const { 2315 return _allocator->used_unlocked(); 2316 } 2317 2318 class SumUsedClosure: public HeapRegionClosure { 2319 size_t _used; 2320 public: 2321 SumUsedClosure() : _used(0) {} 2322 bool doHeapRegion(HeapRegion* r) { 2323 if (!r->is_continues_humongous()) { 2324 _used += r->used(); 2325 } 2326 return false; 2327 } 2328 size_t result() { return _used; } 2329 }; 2330 2331 size_t G1CollectedHeap::recalculate_used() const { 2332 double recalculate_used_start = os::elapsedTime(); 2333 2334 SumUsedClosure blk; 2335 heap_region_iterate(&blk); 2336 2337 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0); 2338 return blk.result(); 2339 } 2340 2341 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 2342 switch (cause) { 2343 case GCCause::_gc_locker: return GCLockerInvokesConcurrent; 2344 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent; 2345 case GCCause::_g1_humongous_allocation: return true; 2346 default: return false; 2347 } 2348 } 2349 2350 #ifndef PRODUCT 2351 void G1CollectedHeap::allocate_dummy_regions() { 2352 // Let's fill up most of the region 2353 size_t word_size = HeapRegion::GrainWords - 1024; 2354 // And as a result the region we'll allocate will be humongous. 2355 guarantee(is_humongous(word_size), "sanity"); 2356 2357 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) { 2358 // Let's use the existing mechanism for the allocation 2359 HeapWord* dummy_obj = humongous_obj_allocate(word_size, 2360 AllocationContext::system()); 2361 if (dummy_obj != NULL) { 2362 MemRegion mr(dummy_obj, word_size); 2363 CollectedHeap::fill_with_object(mr); 2364 } else { 2365 // If we can't allocate once, we probably cannot allocate 2366 // again. Let's get out of the loop. 2367 break; 2368 } 2369 } 2370 } 2371 #endif // !PRODUCT 2372 2373 void G1CollectedHeap::increment_old_marking_cycles_started() { 2374 assert(_old_marking_cycles_started == _old_marking_cycles_completed || 2375 _old_marking_cycles_started == _old_marking_cycles_completed + 1, 2376 err_msg("Wrong marking cycle count (started: %d, completed: %d)", 2377 _old_marking_cycles_started, _old_marking_cycles_completed)); 2378 2379 _old_marking_cycles_started++; 2380 } 2381 2382 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) { 2383 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 2384 2385 // We assume that if concurrent == true, then the caller is a 2386 // concurrent thread that was joined the Suspendible Thread 2387 // Set. If there's ever a cheap way to check this, we should add an 2388 // assert here. 2389 2390 // Given that this method is called at the end of a Full GC or of a 2391 // concurrent cycle, and those can be nested (i.e., a Full GC can 2392 // interrupt a concurrent cycle), the number of full collections 2393 // completed should be either one (in the case where there was no 2394 // nesting) or two (when a Full GC interrupted a concurrent cycle) 2395 // behind the number of full collections started. 2396 2397 // This is the case for the inner caller, i.e. a Full GC. 2398 assert(concurrent || 2399 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || 2400 (_old_marking_cycles_started == _old_marking_cycles_completed + 2), 2401 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u " 2402 "is inconsistent with _old_marking_cycles_completed = %u", 2403 _old_marking_cycles_started, _old_marking_cycles_completed)); 2404 2405 // This is the case for the outer caller, i.e. the concurrent cycle. 2406 assert(!concurrent || 2407 (_old_marking_cycles_started == _old_marking_cycles_completed + 1), 2408 err_msg("for outer caller (concurrent cycle): " 2409 "_old_marking_cycles_started = %u " 2410 "is inconsistent with _old_marking_cycles_completed = %u", 2411 _old_marking_cycles_started, _old_marking_cycles_completed)); 2412 2413 _old_marking_cycles_completed += 1; 2414 2415 // We need to clear the "in_progress" flag in the CM thread before 2416 // we wake up any waiters (especially when ExplicitInvokesConcurrent 2417 // is set) so that if a waiter requests another System.gc() it doesn't 2418 // incorrectly see that a marking cycle is still in progress. 2419 if (concurrent) { 2420 _cmThread->clear_in_progress(); 2421 } 2422 2423 // This notify_all() will ensure that a thread that called 2424 // System.gc() with (with ExplicitGCInvokesConcurrent set or not) 2425 // and it's waiting for a full GC to finish will be woken up. It is 2426 // waiting in VM_G1IncCollectionPause::doit_epilogue(). 2427 FullGCCount_lock->notify_all(); 2428 } 2429 2430 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) { 2431 _concurrent_cycle_started = true; 2432 _gc_timer_cm->register_gc_start(start_time); 2433 2434 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start()); 2435 trace_heap_before_gc(_gc_tracer_cm); 2436 } 2437 2438 void G1CollectedHeap::register_concurrent_cycle_end() { 2439 if (_concurrent_cycle_started) { 2440 if (_cm->has_aborted()) { 2441 _gc_tracer_cm->report_concurrent_mode_failure(); 2442 } 2443 2444 _gc_timer_cm->register_gc_end(); 2445 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions()); 2446 2447 // Clear state variables to prepare for the next concurrent cycle. 2448 _concurrent_cycle_started = false; 2449 _heap_summary_sent = false; 2450 } 2451 } 2452 2453 void G1CollectedHeap::trace_heap_after_concurrent_cycle() { 2454 if (_concurrent_cycle_started) { 2455 // This function can be called when: 2456 // the cleanup pause is run 2457 // the concurrent cycle is aborted before the cleanup pause. 2458 // the concurrent cycle is aborted after the cleanup pause, 2459 // but before the concurrent cycle end has been registered. 2460 // Make sure that we only send the heap information once. 2461 if (!_heap_summary_sent) { 2462 trace_heap_after_gc(_gc_tracer_cm); 2463 _heap_summary_sent = true; 2464 } 2465 } 2466 } 2467 2468 G1YCType G1CollectedHeap::yc_type() { 2469 bool is_young = g1_policy()->gcs_are_young(); 2470 bool is_initial_mark = g1_policy()->during_initial_mark_pause(); 2471 bool is_during_mark = mark_in_progress(); 2472 2473 if (is_initial_mark) { 2474 return InitialMark; 2475 } else if (is_during_mark) { 2476 return DuringMark; 2477 } else if (is_young) { 2478 return Normal; 2479 } else { 2480 return Mixed; 2481 } 2482 } 2483 2484 void G1CollectedHeap::collect(GCCause::Cause cause) { 2485 assert_heap_not_locked(); 2486 2487 unsigned int gc_count_before; 2488 unsigned int old_marking_count_before; 2489 bool retry_gc; 2490 2491 do { 2492 retry_gc = false; 2493 2494 { 2495 MutexLocker ml(Heap_lock); 2496 2497 // Read the GC count while holding the Heap_lock 2498 gc_count_before = total_collections(); 2499 old_marking_count_before = _old_marking_cycles_started; 2500 } 2501 2502 if (should_do_concurrent_full_gc(cause)) { 2503 // Schedule an initial-mark evacuation pause that will start a 2504 // concurrent cycle. We're setting word_size to 0 which means that 2505 // we are not requesting a post-GC allocation. 2506 VM_G1IncCollectionPause op(gc_count_before, 2507 0, /* word_size */ 2508 true, /* should_initiate_conc_mark */ 2509 g1_policy()->max_pause_time_ms(), 2510 cause); 2511 op.set_allocation_context(AllocationContext::current()); 2512 2513 VMThread::execute(&op); 2514 if (!op.pause_succeeded()) { 2515 if (old_marking_count_before == _old_marking_cycles_started) { 2516 retry_gc = op.should_retry_gc(); 2517 } else { 2518 // A Full GC happened while we were trying to schedule the 2519 // initial-mark GC. No point in starting a new cycle given 2520 // that the whole heap was collected anyway. 2521 } 2522 2523 if (retry_gc) { 2524 if (GC_locker::is_active_and_needs_gc()) { 2525 GC_locker::stall_until_clear(); 2526 } 2527 } 2528 } 2529 } else { 2530 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc 2531 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { 2532 2533 // Schedule a standard evacuation pause. We're setting word_size 2534 // to 0 which means that we are not requesting a post-GC allocation. 2535 VM_G1IncCollectionPause op(gc_count_before, 2536 0, /* word_size */ 2537 false, /* should_initiate_conc_mark */ 2538 g1_policy()->max_pause_time_ms(), 2539 cause); 2540 VMThread::execute(&op); 2541 } else { 2542 // Schedule a Full GC. 2543 VM_G1CollectFull op(gc_count_before, old_marking_count_before, cause); 2544 VMThread::execute(&op); 2545 } 2546 } 2547 } while (retry_gc); 2548 } 2549 2550 bool G1CollectedHeap::is_in(const void* p) const { 2551 if (_hrm.reserved().contains(p)) { 2552 // Given that we know that p is in the reserved space, 2553 // heap_region_containing_raw() should successfully 2554 // return the containing region. 2555 HeapRegion* hr = heap_region_containing_raw(p); 2556 return hr->is_in(p); 2557 } else { 2558 return false; 2559 } 2560 } 2561 2562 #ifdef ASSERT 2563 bool G1CollectedHeap::is_in_exact(const void* p) const { 2564 bool contains = reserved_region().contains(p); 2565 bool available = _hrm.is_available(addr_to_region((HeapWord*)p)); 2566 if (contains && available) { 2567 return true; 2568 } else { 2569 return false; 2570 } 2571 } 2572 #endif 2573 2574 // Iteration functions. 2575 2576 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion. 2577 2578 class IterateOopClosureRegionClosure: public HeapRegionClosure { 2579 ExtendedOopClosure* _cl; 2580 public: 2581 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {} 2582 bool doHeapRegion(HeapRegion* r) { 2583 if (!r->is_continues_humongous()) { 2584 r->oop_iterate(_cl); 2585 } 2586 return false; 2587 } 2588 }; 2589 2590 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) { 2591 IterateOopClosureRegionClosure blk(cl); 2592 heap_region_iterate(&blk); 2593 } 2594 2595 // Iterates an ObjectClosure over all objects within a HeapRegion. 2596 2597 class IterateObjectClosureRegionClosure: public HeapRegionClosure { 2598 ObjectClosure* _cl; 2599 public: 2600 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} 2601 bool doHeapRegion(HeapRegion* r) { 2602 if (!r->is_continues_humongous()) { 2603 r->object_iterate(_cl); 2604 } 2605 return false; 2606 } 2607 }; 2608 2609 void G1CollectedHeap::object_iterate(ObjectClosure* cl) { 2610 IterateObjectClosureRegionClosure blk(cl); 2611 heap_region_iterate(&blk); 2612 } 2613 2614 // Calls a SpaceClosure on a HeapRegion. 2615 2616 class SpaceClosureRegionClosure: public HeapRegionClosure { 2617 SpaceClosure* _cl; 2618 public: 2619 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {} 2620 bool doHeapRegion(HeapRegion* r) { 2621 _cl->do_space(r); 2622 return false; 2623 } 2624 }; 2625 2626 void G1CollectedHeap::space_iterate(SpaceClosure* cl) { 2627 SpaceClosureRegionClosure blk(cl); 2628 heap_region_iterate(&blk); 2629 } 2630 2631 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { 2632 _hrm.iterate(cl); 2633 } 2634 2635 void 2636 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl, 2637 uint worker_id, 2638 uint num_workers, 2639 jint claim_value) const { 2640 _hrm.par_iterate(cl, worker_id, num_workers, claim_value); 2641 } 2642 2643 class ResetClaimValuesClosure: public HeapRegionClosure { 2644 public: 2645 bool doHeapRegion(HeapRegion* r) { 2646 r->set_claim_value(HeapRegion::InitialClaimValue); 2647 return false; 2648 } 2649 }; 2650 2651 void G1CollectedHeap::reset_heap_region_claim_values() { 2652 ResetClaimValuesClosure blk; 2653 heap_region_iterate(&blk); 2654 } 2655 2656 void G1CollectedHeap::reset_cset_heap_region_claim_values() { 2657 ResetClaimValuesClosure blk; 2658 collection_set_iterate(&blk); 2659 } 2660 2661 #ifdef ASSERT 2662 // This checks whether all regions in the heap have the correct claim 2663 // value. I also piggy-backed on this a check to ensure that the 2664 // humongous_start_region() information on "continues humongous" 2665 // regions is correct. 2666 2667 class CheckClaimValuesClosure : public HeapRegionClosure { 2668 private: 2669 jint _claim_value; 2670 uint _failures; 2671 HeapRegion* _sh_region; 2672 2673 public: 2674 CheckClaimValuesClosure(jint claim_value) : 2675 _claim_value(claim_value), _failures(0), _sh_region(NULL) { } 2676 bool doHeapRegion(HeapRegion* r) { 2677 if (r->claim_value() != _claim_value) { 2678 gclog_or_tty->print_cr("Region " HR_FORMAT ", " 2679 "claim value = %d, should be %d", 2680 HR_FORMAT_PARAMS(r), 2681 r->claim_value(), _claim_value); 2682 ++_failures; 2683 } 2684 if (!r->is_humongous()) { 2685 _sh_region = NULL; 2686 } else if (r->is_starts_humongous()) { 2687 _sh_region = r; 2688 } else if (r->is_continues_humongous()) { 2689 if (r->humongous_start_region() != _sh_region) { 2690 gclog_or_tty->print_cr("Region " HR_FORMAT ", " 2691 "HS = "PTR_FORMAT", should be "PTR_FORMAT, 2692 HR_FORMAT_PARAMS(r), 2693 r->humongous_start_region(), 2694 _sh_region); 2695 ++_failures; 2696 } 2697 } 2698 return false; 2699 } 2700 uint failures() { return _failures; } 2701 }; 2702 2703 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) { 2704 CheckClaimValuesClosure cl(claim_value); 2705 heap_region_iterate(&cl); 2706 return cl.failures() == 0; 2707 } 2708 2709 class CheckClaimValuesInCSetHRClosure: public HeapRegionClosure { 2710 private: 2711 jint _claim_value; 2712 uint _failures; 2713 2714 public: 2715 CheckClaimValuesInCSetHRClosure(jint claim_value) : 2716 _claim_value(claim_value), _failures(0) { } 2717 2718 uint failures() { return _failures; } 2719 2720 bool doHeapRegion(HeapRegion* hr) { 2721 assert(hr->in_collection_set(), "how?"); 2722 assert(!hr->is_humongous(), "H-region in CSet"); 2723 if (hr->claim_value() != _claim_value) { 2724 gclog_or_tty->print_cr("CSet Region " HR_FORMAT ", " 2725 "claim value = %d, should be %d", 2726 HR_FORMAT_PARAMS(hr), 2727 hr->claim_value(), _claim_value); 2728 _failures += 1; 2729 } 2730 return false; 2731 } 2732 }; 2733 2734 bool G1CollectedHeap::check_cset_heap_region_claim_values(jint claim_value) { 2735 CheckClaimValuesInCSetHRClosure cl(claim_value); 2736 collection_set_iterate(&cl); 2737 return cl.failures() == 0; 2738 } 2739 #endif // ASSERT 2740 2741 // Clear the cached CSet starting regions and (more importantly) 2742 // the time stamps. Called when we reset the GC time stamp. 2743 void G1CollectedHeap::clear_cset_start_regions() { 2744 assert(_worker_cset_start_region != NULL, "sanity"); 2745 assert(_worker_cset_start_region_time_stamp != NULL, "sanity"); 2746 2747 int n_queues = MAX2((int)ParallelGCThreads, 1); 2748 for (int i = 0; i < n_queues; i++) { 2749 _worker_cset_start_region[i] = NULL; 2750 _worker_cset_start_region_time_stamp[i] = 0; 2751 } 2752 } 2753 2754 // Given the id of a worker, obtain or calculate a suitable 2755 // starting region for iterating over the current collection set. 2756 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) { 2757 assert(get_gc_time_stamp() > 0, "should have been updated by now"); 2758 2759 HeapRegion* result = NULL; 2760 unsigned gc_time_stamp = get_gc_time_stamp(); 2761 2762 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) { 2763 // Cached starting region for current worker was set 2764 // during the current pause - so it's valid. 2765 // Note: the cached starting heap region may be NULL 2766 // (when the collection set is empty). 2767 result = _worker_cset_start_region[worker_i]; 2768 assert(result == NULL || result->in_collection_set(), "sanity"); 2769 return result; 2770 } 2771 2772 // The cached entry was not valid so let's calculate 2773 // a suitable starting heap region for this worker. 2774 2775 // We want the parallel threads to start their collection 2776 // set iteration at different collection set regions to 2777 // avoid contention. 2778 // If we have: 2779 // n collection set regions 2780 // p threads 2781 // Then thread t will start at region floor ((t * n) / p) 2782 2783 result = g1_policy()->collection_set(); 2784 if (G1CollectedHeap::use_parallel_gc_threads()) { 2785 uint cs_size = g1_policy()->cset_region_length(); 2786 uint active_workers = workers()->active_workers(); 2787 assert(UseDynamicNumberOfGCThreads || 2788 active_workers == workers()->total_workers(), 2789 "Unless dynamic should use total workers"); 2790 2791 uint end_ind = (cs_size * worker_i) / active_workers; 2792 uint start_ind = 0; 2793 2794 if (worker_i > 0 && 2795 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) { 2796 // Previous workers starting region is valid 2797 // so let's iterate from there 2798 start_ind = (cs_size * (worker_i - 1)) / active_workers; 2799 result = _worker_cset_start_region[worker_i - 1]; 2800 } 2801 2802 for (uint i = start_ind; i < end_ind; i++) { 2803 result = result->next_in_collection_set(); 2804 } 2805 } 2806 2807 // Note: the calculated starting heap region may be NULL 2808 // (when the collection set is empty). 2809 assert(result == NULL || result->in_collection_set(), "sanity"); 2810 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp, 2811 "should be updated only once per pause"); 2812 _worker_cset_start_region[worker_i] = result; 2813 OrderAccess::storestore(); 2814 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp; 2815 return result; 2816 } 2817 2818 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) { 2819 HeapRegion* r = g1_policy()->collection_set(); 2820 while (r != NULL) { 2821 HeapRegion* next = r->next_in_collection_set(); 2822 if (cl->doHeapRegion(r)) { 2823 cl->incomplete(); 2824 return; 2825 } 2826 r = next; 2827 } 2828 } 2829 2830 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r, 2831 HeapRegionClosure *cl) { 2832 if (r == NULL) { 2833 // The CSet is empty so there's nothing to do. 2834 return; 2835 } 2836 2837 assert(r->in_collection_set(), 2838 "Start region must be a member of the collection set."); 2839 HeapRegion* cur = r; 2840 while (cur != NULL) { 2841 HeapRegion* next = cur->next_in_collection_set(); 2842 if (cl->doHeapRegion(cur) && false) { 2843 cl->incomplete(); 2844 return; 2845 } 2846 cur = next; 2847 } 2848 cur = g1_policy()->collection_set(); 2849 while (cur != r) { 2850 HeapRegion* next = cur->next_in_collection_set(); 2851 if (cl->doHeapRegion(cur) && false) { 2852 cl->incomplete(); 2853 return; 2854 } 2855 cur = next; 2856 } 2857 } 2858 2859 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const { 2860 HeapRegion* result = _hrm.next_region_in_heap(from); 2861 while (result != NULL && result->is_humongous()) { 2862 result = _hrm.next_region_in_heap(result); 2863 } 2864 return result; 2865 } 2866 2867 Space* G1CollectedHeap::space_containing(const void* addr) const { 2868 return heap_region_containing(addr); 2869 } 2870 2871 HeapWord* G1CollectedHeap::block_start(const void* addr) const { 2872 Space* sp = space_containing(addr); 2873 return sp->block_start(addr); 2874 } 2875 2876 size_t G1CollectedHeap::block_size(const HeapWord* addr) const { 2877 Space* sp = space_containing(addr); 2878 return sp->block_size(addr); 2879 } 2880 2881 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { 2882 Space* sp = space_containing(addr); 2883 return sp->block_is_obj(addr); 2884 } 2885 2886 bool G1CollectedHeap::supports_tlab_allocation() const { 2887 return true; 2888 } 2889 2890 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { 2891 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes; 2892 } 2893 2894 size_t G1CollectedHeap::tlab_used(Thread* ignored) const { 2895 return young_list()->eden_used_bytes(); 2896 } 2897 2898 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size 2899 // must be smaller than the humongous object limit. 2900 size_t G1CollectedHeap::max_tlab_size() const { 2901 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment); 2902 } 2903 2904 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { 2905 // Return the remaining space in the cur alloc region, but not less than 2906 // the min TLAB size. 2907 2908 // Also, this value can be at most the humongous object threshold, 2909 // since we can't allow tlabs to grow big enough to accommodate 2910 // humongous objects. 2911 2912 HeapRegion* hr = _allocator->mutator_alloc_region(AllocationContext::current())->get(); 2913 size_t max_tlab = max_tlab_size() * wordSize; 2914 if (hr == NULL) { 2915 return max_tlab; 2916 } else { 2917 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab); 2918 } 2919 } 2920 2921 size_t G1CollectedHeap::max_capacity() const { 2922 return _hrm.reserved().byte_size(); 2923 } 2924 2925 jlong G1CollectedHeap::millis_since_last_gc() { 2926 // assert(false, "NYI"); 2927 return 0; 2928 } 2929 2930 void G1CollectedHeap::prepare_for_verify() { 2931 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) { 2932 ensure_parsability(false); 2933 } 2934 g1_rem_set()->prepare_for_verify(); 2935 } 2936 2937 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr, 2938 VerifyOption vo) { 2939 switch (vo) { 2940 case VerifyOption_G1UsePrevMarking: 2941 return hr->obj_allocated_since_prev_marking(obj); 2942 case VerifyOption_G1UseNextMarking: 2943 return hr->obj_allocated_since_next_marking(obj); 2944 case VerifyOption_G1UseMarkWord: 2945 return false; 2946 default: 2947 ShouldNotReachHere(); 2948 } 2949 return false; // keep some compilers happy 2950 } 2951 2952 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) { 2953 switch (vo) { 2954 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start(); 2955 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start(); 2956 case VerifyOption_G1UseMarkWord: return NULL; 2957 default: ShouldNotReachHere(); 2958 } 2959 return NULL; // keep some compilers happy 2960 } 2961 2962 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) { 2963 switch (vo) { 2964 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj); 2965 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj); 2966 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked(); 2967 default: ShouldNotReachHere(); 2968 } 2969 return false; // keep some compilers happy 2970 } 2971 2972 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) { 2973 switch (vo) { 2974 case VerifyOption_G1UsePrevMarking: return "PTAMS"; 2975 case VerifyOption_G1UseNextMarking: return "NTAMS"; 2976 case VerifyOption_G1UseMarkWord: return "NONE"; 2977 default: ShouldNotReachHere(); 2978 } 2979 return NULL; // keep some compilers happy 2980 } 2981 2982 class VerifyRootsClosure: public OopClosure { 2983 private: 2984 G1CollectedHeap* _g1h; 2985 VerifyOption _vo; 2986 bool _failures; 2987 public: 2988 // _vo == UsePrevMarking -> use "prev" marking information, 2989 // _vo == UseNextMarking -> use "next" marking information, 2990 // _vo == UseMarkWord -> use mark word from object header. 2991 VerifyRootsClosure(VerifyOption vo) : 2992 _g1h(G1CollectedHeap::heap()), 2993 _vo(vo), 2994 _failures(false) { } 2995 2996 bool failures() { return _failures; } 2997 2998 template <class T> void do_oop_nv(T* p) { 2999 T heap_oop = oopDesc::load_heap_oop(p); 3000 if (!oopDesc::is_null(heap_oop)) { 3001 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 3002 if (_g1h->is_obj_dead_cond(obj, _vo)) { 3003 gclog_or_tty->print_cr("Root location "PTR_FORMAT" " 3004 "points to dead obj "PTR_FORMAT, p, (void*) obj); 3005 if (_vo == VerifyOption_G1UseMarkWord) { 3006 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark())); 3007 } 3008 obj->print_on(gclog_or_tty); 3009 _failures = true; 3010 } 3011 } 3012 } 3013 3014 void do_oop(oop* p) { do_oop_nv(p); } 3015 void do_oop(narrowOop* p) { do_oop_nv(p); } 3016 }; 3017 3018 class G1VerifyCodeRootOopClosure: public OopClosure { 3019 G1CollectedHeap* _g1h; 3020 OopClosure* _root_cl; 3021 nmethod* _nm; 3022 VerifyOption _vo; 3023 bool _failures; 3024 3025 template <class T> void do_oop_work(T* p) { 3026 // First verify that this root is live 3027 _root_cl->do_oop(p); 3028 3029 if (!G1VerifyHeapRegionCodeRoots) { 3030 // We're not verifying the code roots attached to heap region. 3031 return; 3032 } 3033 3034 // Don't check the code roots during marking verification in a full GC 3035 if (_vo == VerifyOption_G1UseMarkWord) { 3036 return; 3037 } 3038 3039 // Now verify that the current nmethod (which contains p) is 3040 // in the code root list of the heap region containing the 3041 // object referenced by p. 3042 3043 T heap_oop = oopDesc::load_heap_oop(p); 3044 if (!oopDesc::is_null(heap_oop)) { 3045 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 3046 3047 // Now fetch the region containing the object 3048 HeapRegion* hr = _g1h->heap_region_containing(obj); 3049 HeapRegionRemSet* hrrs = hr->rem_set(); 3050 // Verify that the strong code root list for this region 3051 // contains the nmethod 3052 if (!hrrs->strong_code_roots_list_contains(_nm)) { 3053 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" " 3054 "from nmethod "PTR_FORMAT" not in strong " 3055 "code roots for region ["PTR_FORMAT","PTR_FORMAT")", 3056 p, _nm, hr->bottom(), hr->end()); 3057 _failures = true; 3058 } 3059 } 3060 } 3061 3062 public: 3063 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo): 3064 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {} 3065 3066 void do_oop(oop* p) { do_oop_work(p); } 3067 void do_oop(narrowOop* p) { do_oop_work(p); } 3068 3069 void set_nmethod(nmethod* nm) { _nm = nm; } 3070 bool failures() { return _failures; } 3071 }; 3072 3073 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure { 3074 G1VerifyCodeRootOopClosure* _oop_cl; 3075 3076 public: 3077 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl): 3078 _oop_cl(oop_cl) {} 3079 3080 void do_code_blob(CodeBlob* cb) { 3081 nmethod* nm = cb->as_nmethod_or_null(); 3082 if (nm != NULL) { 3083 _oop_cl->set_nmethod(nm); 3084 nm->oops_do(_oop_cl); 3085 } 3086 } 3087 }; 3088 3089 class YoungRefCounterClosure : public OopClosure { 3090 G1CollectedHeap* _g1h; 3091 int _count; 3092 public: 3093 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {} 3094 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } } 3095 void do_oop(narrowOop* p) { ShouldNotReachHere(); } 3096 3097 int count() { return _count; } 3098 void reset_count() { _count = 0; }; 3099 }; 3100 3101 class VerifyKlassClosure: public KlassClosure { 3102 YoungRefCounterClosure _young_ref_counter_closure; 3103 OopClosure *_oop_closure; 3104 public: 3105 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {} 3106 void do_klass(Klass* k) { 3107 k->oops_do(_oop_closure); 3108 3109 _young_ref_counter_closure.reset_count(); 3110 k->oops_do(&_young_ref_counter_closure); 3111 if (_young_ref_counter_closure.count() > 0) { 3112 guarantee(k->has_modified_oops(), err_msg("Klass " PTR_FORMAT ", has young refs but is not dirty.", k)); 3113 } 3114 } 3115 }; 3116 3117 class VerifyLivenessOopClosure: public OopClosure { 3118 G1CollectedHeap* _g1h; 3119 VerifyOption _vo; 3120 public: 3121 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo): 3122 _g1h(g1h), _vo(vo) 3123 { } 3124 void do_oop(narrowOop *p) { do_oop_work(p); } 3125 void do_oop( oop *p) { do_oop_work(p); } 3126 3127 template <class T> void do_oop_work(T *p) { 3128 oop obj = oopDesc::load_decode_heap_oop(p); 3129 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo), 3130 "Dead object referenced by a not dead object"); 3131 } 3132 }; 3133 3134 class VerifyObjsInRegionClosure: public ObjectClosure { 3135 private: 3136 G1CollectedHeap* _g1h; 3137 size_t _live_bytes; 3138 HeapRegion *_hr; 3139 VerifyOption _vo; 3140 public: 3141 // _vo == UsePrevMarking -> use "prev" marking information, 3142 // _vo == UseNextMarking -> use "next" marking information, 3143 // _vo == UseMarkWord -> use mark word from object header. 3144 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo) 3145 : _live_bytes(0), _hr(hr), _vo(vo) { 3146 _g1h = G1CollectedHeap::heap(); 3147 } 3148 void do_object(oop o) { 3149 VerifyLivenessOopClosure isLive(_g1h, _vo); 3150 assert(o != NULL, "Huh?"); 3151 if (!_g1h->is_obj_dead_cond(o, _vo)) { 3152 // If the object is alive according to the mark word, 3153 // then verify that the marking information agrees. 3154 // Note we can't verify the contra-positive of the 3155 // above: if the object is dead (according to the mark 3156 // word), it may not be marked, or may have been marked 3157 // but has since became dead, or may have been allocated 3158 // since the last marking. 3159 if (_vo == VerifyOption_G1UseMarkWord) { 3160 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch"); 3161 } 3162 3163 o->oop_iterate_no_header(&isLive); 3164 if (!_hr->obj_allocated_since_prev_marking(o)) { 3165 size_t obj_size = o->size(); // Make sure we don't overflow 3166 _live_bytes += (obj_size * HeapWordSize); 3167 } 3168 } 3169 } 3170 size_t live_bytes() { return _live_bytes; } 3171 }; 3172 3173 class PrintObjsInRegionClosure : public ObjectClosure { 3174 HeapRegion *_hr; 3175 G1CollectedHeap *_g1; 3176 public: 3177 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) { 3178 _g1 = G1CollectedHeap::heap(); 3179 }; 3180 3181 void do_object(oop o) { 3182 if (o != NULL) { 3183 HeapWord *start = (HeapWord *) o; 3184 size_t word_sz = o->size(); 3185 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT 3186 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n", 3187 (void*) o, word_sz, 3188 _g1->isMarkedPrev(o), 3189 _g1->isMarkedNext(o), 3190 _hr->obj_allocated_since_prev_marking(o)); 3191 HeapWord *end = start + word_sz; 3192 HeapWord *cur; 3193 int *val; 3194 for (cur = start; cur < end; cur++) { 3195 val = (int *) cur; 3196 gclog_or_tty->print("\t "PTR_FORMAT":%d\n", val, *val); 3197 } 3198 } 3199 } 3200 }; 3201 3202 class VerifyRegionClosure: public HeapRegionClosure { 3203 private: 3204 bool _par; 3205 VerifyOption _vo; 3206 bool _failures; 3207 public: 3208 // _vo == UsePrevMarking -> use "prev" marking information, 3209 // _vo == UseNextMarking -> use "next" marking information, 3210 // _vo == UseMarkWord -> use mark word from object header. 3211 VerifyRegionClosure(bool par, VerifyOption vo) 3212 : _par(par), 3213 _vo(vo), 3214 _failures(false) {} 3215 3216 bool failures() { 3217 return _failures; 3218 } 3219 3220 bool doHeapRegion(HeapRegion* r) { 3221 if (!r->is_continues_humongous()) { 3222 bool failures = false; 3223 r->verify(_vo, &failures); 3224 if (failures) { 3225 _failures = true; 3226 } else { 3227 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo); 3228 r->object_iterate(¬_dead_yet_cl); 3229 if (_vo != VerifyOption_G1UseNextMarking) { 3230 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) { 3231 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] " 3232 "max_live_bytes "SIZE_FORMAT" " 3233 "< calculated "SIZE_FORMAT, 3234 r->bottom(), r->end(), 3235 r->max_live_bytes(), 3236 not_dead_yet_cl.live_bytes()); 3237 _failures = true; 3238 } 3239 } else { 3240 // When vo == UseNextMarking we cannot currently do a sanity 3241 // check on the live bytes as the calculation has not been 3242 // finalized yet. 3243 } 3244 } 3245 } 3246 return false; // stop the region iteration if we hit a failure 3247 } 3248 }; 3249 3250 // This is the task used for parallel verification of the heap regions 3251 3252 class G1ParVerifyTask: public AbstractGangTask { 3253 private: 3254 G1CollectedHeap* _g1h; 3255 VerifyOption _vo; 3256 bool _failures; 3257 3258 public: 3259 // _vo == UsePrevMarking -> use "prev" marking information, 3260 // _vo == UseNextMarking -> use "next" marking information, 3261 // _vo == UseMarkWord -> use mark word from object header. 3262 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) : 3263 AbstractGangTask("Parallel verify task"), 3264 _g1h(g1h), 3265 _vo(vo), 3266 _failures(false) { } 3267 3268 bool failures() { 3269 return _failures; 3270 } 3271 3272 void work(uint worker_id) { 3273 HandleMark hm; 3274 VerifyRegionClosure blk(true, _vo); 3275 _g1h->heap_region_par_iterate_chunked(&blk, worker_id, 3276 _g1h->workers()->active_workers(), 3277 HeapRegion::ParVerifyClaimValue); 3278 if (blk.failures()) { 3279 _failures = true; 3280 } 3281 } 3282 }; 3283 3284 void G1CollectedHeap::verify(bool silent, VerifyOption vo) { 3285 if (SafepointSynchronize::is_at_safepoint()) { 3286 assert(Thread::current()->is_VM_thread(), 3287 "Expected to be executed serially by the VM thread at this point"); 3288 3289 if (!silent) { gclog_or_tty->print("Roots "); } 3290 VerifyRootsClosure rootsCl(vo); 3291 VerifyKlassClosure klassCl(this, &rootsCl); 3292 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false); 3293 3294 // We apply the relevant closures to all the oops in the 3295 // system dictionary, class loader data graph, the string table 3296 // and the nmethods in the code cache. 3297 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo); 3298 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl); 3299 3300 process_all_roots(true, // activate StrongRootsScope 3301 SO_AllCodeCache, // roots scanning options 3302 &rootsCl, 3303 &cldCl, 3304 &blobsCl); 3305 3306 bool failures = rootsCl.failures() || codeRootsCl.failures(); 3307 3308 if (vo != VerifyOption_G1UseMarkWord) { 3309 // If we're verifying during a full GC then the region sets 3310 // will have been torn down at the start of the GC. Therefore 3311 // verifying the region sets will fail. So we only verify 3312 // the region sets when not in a full GC. 3313 if (!silent) { gclog_or_tty->print("HeapRegionSets "); } 3314 verify_region_sets(); 3315 } 3316 3317 if (!silent) { gclog_or_tty->print("HeapRegions "); } 3318 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) { 3319 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue), 3320 "sanity check"); 3321 3322 G1ParVerifyTask task(this, vo); 3323 assert(UseDynamicNumberOfGCThreads || 3324 workers()->active_workers() == workers()->total_workers(), 3325 "If not dynamic should be using all the workers"); 3326 int n_workers = workers()->active_workers(); 3327 set_par_threads(n_workers); 3328 workers()->run_task(&task); 3329 set_par_threads(0); 3330 if (task.failures()) { 3331 failures = true; 3332 } 3333 3334 // Checks that the expected amount of parallel work was done. 3335 // The implication is that n_workers is > 0. 3336 assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue), 3337 "sanity check"); 3338 3339 reset_heap_region_claim_values(); 3340 3341 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue), 3342 "sanity check"); 3343 } else { 3344 VerifyRegionClosure blk(false, vo); 3345 heap_region_iterate(&blk); 3346 if (blk.failures()) { 3347 failures = true; 3348 } 3349 } 3350 if (!silent) gclog_or_tty->print("RemSet "); 3351 rem_set()->verify(); 3352 3353 if (G1StringDedup::is_enabled()) { 3354 if (!silent) gclog_or_tty->print("StrDedup "); 3355 G1StringDedup::verify(); 3356 } 3357 3358 if (failures) { 3359 gclog_or_tty->print_cr("Heap:"); 3360 // It helps to have the per-region information in the output to 3361 // help us track down what went wrong. This is why we call 3362 // print_extended_on() instead of print_on(). 3363 print_extended_on(gclog_or_tty); 3364 gclog_or_tty->cr(); 3365 #ifndef PRODUCT 3366 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) { 3367 concurrent_mark()->print_reachable("at-verification-failure", 3368 vo, false /* all */); 3369 } 3370 #endif 3371 gclog_or_tty->flush(); 3372 } 3373 guarantee(!failures, "there should not have been any failures"); 3374 } else { 3375 if (!silent) { 3376 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet"); 3377 if (G1StringDedup::is_enabled()) { 3378 gclog_or_tty->print(", StrDedup"); 3379 } 3380 gclog_or_tty->print(") "); 3381 } 3382 } 3383 } 3384 3385 void G1CollectedHeap::verify(bool silent) { 3386 verify(silent, VerifyOption_G1UsePrevMarking); 3387 } 3388 3389 double G1CollectedHeap::verify(bool guard, const char* msg) { 3390 double verify_time_ms = 0.0; 3391 3392 if (guard && total_collections() >= VerifyGCStartAt) { 3393 double verify_start = os::elapsedTime(); 3394 HandleMark hm; // Discard invalid handles created during verification 3395 prepare_for_verify(); 3396 Universe::verify(VerifyOption_G1UsePrevMarking, msg); 3397 verify_time_ms = (os::elapsedTime() - verify_start) * 1000; 3398 } 3399 3400 return verify_time_ms; 3401 } 3402 3403 void G1CollectedHeap::verify_before_gc() { 3404 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:"); 3405 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms); 3406 } 3407 3408 void G1CollectedHeap::verify_after_gc() { 3409 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:"); 3410 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms); 3411 } 3412 3413 class PrintRegionClosure: public HeapRegionClosure { 3414 outputStream* _st; 3415 public: 3416 PrintRegionClosure(outputStream* st) : _st(st) {} 3417 bool doHeapRegion(HeapRegion* r) { 3418 r->print_on(_st); 3419 return false; 3420 } 3421 }; 3422 3423 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 3424 const HeapRegion* hr, 3425 const VerifyOption vo) const { 3426 switch (vo) { 3427 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); 3428 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); 3429 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked(); 3430 default: ShouldNotReachHere(); 3431 } 3432 return false; // keep some compilers happy 3433 } 3434 3435 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 3436 const VerifyOption vo) const { 3437 switch (vo) { 3438 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); 3439 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); 3440 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked(); 3441 default: ShouldNotReachHere(); 3442 } 3443 return false; // keep some compilers happy 3444 } 3445 3446 void G1CollectedHeap::print_on(outputStream* st) const { 3447 st->print(" %-20s", "garbage-first heap"); 3448 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 3449 capacity()/K, used_unlocked()/K); 3450 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")", 3451 _hrm.reserved().start(), 3452 _hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords, 3453 _hrm.reserved().end()); 3454 st->cr(); 3455 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); 3456 uint young_regions = _young_list->length(); 3457 st->print("%u young (" SIZE_FORMAT "K), ", young_regions, 3458 (size_t) young_regions * HeapRegion::GrainBytes / K); 3459 uint survivor_regions = g1_policy()->recorded_survivor_regions(); 3460 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, 3461 (size_t) survivor_regions * HeapRegion::GrainBytes / K); 3462 st->cr(); 3463 MetaspaceAux::print_on(st); 3464 } 3465 3466 void G1CollectedHeap::print_extended_on(outputStream* st) const { 3467 print_on(st); 3468 3469 // Print the per-region information. 3470 st->cr(); 3471 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), " 3472 "HS=humongous(starts), HC=humongous(continues), " 3473 "CS=collection set, F=free, TS=gc time stamp, " 3474 "PTAMS=previous top-at-mark-start, " 3475 "NTAMS=next top-at-mark-start)"); 3476 PrintRegionClosure blk(st); 3477 heap_region_iterate(&blk); 3478 } 3479 3480 void G1CollectedHeap::print_on_error(outputStream* st) const { 3481 this->CollectedHeap::print_on_error(st); 3482 3483 if (_cm != NULL) { 3484 st->cr(); 3485 _cm->print_on_error(st); 3486 } 3487 } 3488 3489 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const { 3490 if (G1CollectedHeap::use_parallel_gc_threads()) { 3491 workers()->print_worker_threads_on(st); 3492 } 3493 _cmThread->print_on(st); 3494 st->cr(); 3495 _cm->print_worker_threads_on(st); 3496 _cg1r->print_worker_threads_on(st); 3497 if (G1StringDedup::is_enabled()) { 3498 G1StringDedup::print_worker_threads_on(st); 3499 } 3500 } 3501 3502 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { 3503 if (G1CollectedHeap::use_parallel_gc_threads()) { 3504 workers()->threads_do(tc); 3505 } 3506 tc->do_thread(_cmThread); 3507 _cg1r->threads_do(tc); 3508 if (G1StringDedup::is_enabled()) { 3509 G1StringDedup::threads_do(tc); 3510 } 3511 } 3512 3513 void G1CollectedHeap::print_tracing_info() const { 3514 // We'll overload this to mean "trace GC pause statistics." 3515 if (TraceYoungGenTime || TraceOldGenTime) { 3516 // The "G1CollectorPolicy" is keeping track of these stats, so delegate 3517 // to that. 3518 g1_policy()->print_tracing_info(); 3519 } 3520 if (G1SummarizeRSetStats) { 3521 g1_rem_set()->print_summary_info(); 3522 } 3523 if (G1SummarizeConcMark) { 3524 concurrent_mark()->print_summary_info(); 3525 } 3526 g1_policy()->print_yg_surv_rate_info(); 3527 SpecializationStats::print(); 3528 } 3529 3530 #ifndef PRODUCT 3531 // Helpful for debugging RSet issues. 3532 3533 class PrintRSetsClosure : public HeapRegionClosure { 3534 private: 3535 const char* _msg; 3536 size_t _occupied_sum; 3537 3538 public: 3539 bool doHeapRegion(HeapRegion* r) { 3540 HeapRegionRemSet* hrrs = r->rem_set(); 3541 size_t occupied = hrrs->occupied(); 3542 _occupied_sum += occupied; 3543 3544 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT, 3545 HR_FORMAT_PARAMS(r)); 3546 if (occupied == 0) { 3547 gclog_or_tty->print_cr(" RSet is empty"); 3548 } else { 3549 hrrs->print(); 3550 } 3551 gclog_or_tty->print_cr("----------"); 3552 return false; 3553 } 3554 3555 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { 3556 gclog_or_tty->cr(); 3557 gclog_or_tty->print_cr("========================================"); 3558 gclog_or_tty->print_cr("%s", msg); 3559 gclog_or_tty->cr(); 3560 } 3561 3562 ~PrintRSetsClosure() { 3563 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum); 3564 gclog_or_tty->print_cr("========================================"); 3565 gclog_or_tty->cr(); 3566 } 3567 }; 3568 3569 void G1CollectedHeap::print_cset_rsets() { 3570 PrintRSetsClosure cl("Printing CSet RSets"); 3571 collection_set_iterate(&cl); 3572 } 3573 3574 void G1CollectedHeap::print_all_rsets() { 3575 PrintRSetsClosure cl("Printing All RSets");; 3576 heap_region_iterate(&cl); 3577 } 3578 #endif // PRODUCT 3579 3580 G1CollectedHeap* G1CollectedHeap::heap() { 3581 assert(_sh->kind() == CollectedHeap::G1CollectedHeap, 3582 "not a garbage-first heap"); 3583 return _g1h; 3584 } 3585 3586 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) { 3587 // always_do_update_barrier = false; 3588 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 3589 // Fill TLAB's and such 3590 accumulate_statistics_all_tlabs(); 3591 ensure_parsability(true); 3592 3593 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) && 3594 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) { 3595 g1_rem_set()->print_periodic_summary_info("Before GC RS summary"); 3596 } 3597 } 3598 3599 void G1CollectedHeap::gc_epilogue(bool full) { 3600 3601 if (G1SummarizeRSetStats && 3602 (G1SummarizeRSetStatsPeriod > 0) && 3603 // we are at the end of the GC. Total collections has already been increased. 3604 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) { 3605 g1_rem_set()->print_periodic_summary_info("After GC RS summary"); 3606 } 3607 3608 // FIXME: what is this about? 3609 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" 3610 // is set. 3611 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(), 3612 "derived pointer present")); 3613 // always_do_update_barrier = true; 3614 3615 resize_all_tlabs(); 3616 allocation_context_stats().update(full); 3617 3618 // We have just completed a GC. Update the soft reference 3619 // policy with the new heap occupancy 3620 Universe::update_heap_info_at_gc(); 3621 } 3622 3623 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, 3624 unsigned int gc_count_before, 3625 bool* succeeded, 3626 GCCause::Cause gc_cause) { 3627 assert_heap_not_locked_and_not_at_safepoint(); 3628 g1_policy()->record_stop_world_start(); 3629 VM_G1IncCollectionPause op(gc_count_before, 3630 word_size, 3631 false, /* should_initiate_conc_mark */ 3632 g1_policy()->max_pause_time_ms(), 3633 gc_cause); 3634 3635 op.set_allocation_context(AllocationContext::current()); 3636 VMThread::execute(&op); 3637 3638 HeapWord* result = op.result(); 3639 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded(); 3640 assert(result == NULL || ret_succeeded, 3641 "the result should be NULL if the VM did not succeed"); 3642 *succeeded = ret_succeeded; 3643 3644 assert_heap_not_locked(); 3645 return result; 3646 } 3647 3648 void 3649 G1CollectedHeap::doConcurrentMark() { 3650 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); 3651 if (!_cmThread->in_progress()) { 3652 _cmThread->set_started(); 3653 CGC_lock->notify(); 3654 } 3655 } 3656 3657 size_t G1CollectedHeap::pending_card_num() { 3658 size_t extra_cards = 0; 3659 JavaThread *curr = Threads::first(); 3660 while (curr != NULL) { 3661 DirtyCardQueue& dcq = curr->dirty_card_queue(); 3662 extra_cards += dcq.size(); 3663 curr = curr->next(); 3664 } 3665 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 3666 size_t buffer_size = dcqs.buffer_size(); 3667 size_t buffer_num = dcqs.completed_buffers_num(); 3668 3669 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes 3670 // in bytes - not the number of 'entries'. We need to convert 3671 // into a number of cards. 3672 return (buffer_size * buffer_num + extra_cards) / oopSize; 3673 } 3674 3675 size_t G1CollectedHeap::cards_scanned() { 3676 return g1_rem_set()->cardsScanned(); 3677 } 3678 3679 bool G1CollectedHeap::humongous_region_is_always_live(uint index) { 3680 HeapRegion* region = region_at(index); 3681 assert(region->is_starts_humongous(), "Must start a humongous object"); 3682 return oop(region->bottom())->is_objArray() || !region->rem_set()->is_empty(); 3683 } 3684 3685 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure { 3686 private: 3687 size_t _total_humongous; 3688 size_t _candidate_humongous; 3689 public: 3690 RegisterHumongousWithInCSetFastTestClosure() : _total_humongous(0), _candidate_humongous(0) { 3691 } 3692 3693 virtual bool doHeapRegion(HeapRegion* r) { 3694 if (!r->is_starts_humongous()) { 3695 return false; 3696 } 3697 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 3698 3699 uint region_idx = r->hrm_index(); 3700 bool is_candidate = !g1h->humongous_region_is_always_live(region_idx); 3701 // Is_candidate already filters out humongous regions with some remembered set. 3702 // This will not lead to humongous object that we mistakenly keep alive because 3703 // during young collection the remembered sets will only be added to. 3704 if (is_candidate) { 3705 g1h->register_humongous_region_with_in_cset_fast_test(region_idx); 3706 _candidate_humongous++; 3707 } 3708 _total_humongous++; 3709 3710 return false; 3711 } 3712 3713 size_t total_humongous() const { return _total_humongous; } 3714 size_t candidate_humongous() const { return _candidate_humongous; } 3715 }; 3716 3717 void G1CollectedHeap::register_humongous_regions_with_in_cset_fast_test() { 3718 if (!G1ReclaimDeadHumongousObjectsAtYoungGC) { 3719 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0, 0); 3720 return; 3721 } 3722 3723 RegisterHumongousWithInCSetFastTestClosure cl; 3724 heap_region_iterate(&cl); 3725 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(cl.total_humongous(), 3726 cl.candidate_humongous()); 3727 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0; 3728 3729 if (_has_humongous_reclaim_candidates) { 3730 clear_humongous_is_live_table(); 3731 } 3732 } 3733 3734 void 3735 G1CollectedHeap::setup_surviving_young_words() { 3736 assert(_surviving_young_words == NULL, "pre-condition"); 3737 uint array_length = g1_policy()->young_cset_region_length(); 3738 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC); 3739 if (_surviving_young_words == NULL) { 3740 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR, 3741 "Not enough space for young surv words summary."); 3742 } 3743 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t)); 3744 #ifdef ASSERT 3745 for (uint i = 0; i < array_length; ++i) { 3746 assert( _surviving_young_words[i] == 0, "memset above" ); 3747 } 3748 #endif // !ASSERT 3749 } 3750 3751 void 3752 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) { 3753 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); 3754 uint array_length = g1_policy()->young_cset_region_length(); 3755 for (uint i = 0; i < array_length; ++i) { 3756 _surviving_young_words[i] += surv_young_words[i]; 3757 } 3758 } 3759 3760 void 3761 G1CollectedHeap::cleanup_surviving_young_words() { 3762 guarantee( _surviving_young_words != NULL, "pre-condition" ); 3763 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words, mtGC); 3764 _surviving_young_words = NULL; 3765 } 3766 3767 #ifdef ASSERT 3768 class VerifyCSetClosure: public HeapRegionClosure { 3769 public: 3770 bool doHeapRegion(HeapRegion* hr) { 3771 // Here we check that the CSet region's RSet is ready for parallel 3772 // iteration. The fields that we'll verify are only manipulated 3773 // when the region is part of a CSet and is collected. Afterwards, 3774 // we reset these fields when we clear the region's RSet (when the 3775 // region is freed) so they are ready when the region is 3776 // re-allocated. The only exception to this is if there's an 3777 // evacuation failure and instead of freeing the region we leave 3778 // it in the heap. In that case, we reset these fields during 3779 // evacuation failure handling. 3780 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification"); 3781 3782 // Here's a good place to add any other checks we'd like to 3783 // perform on CSet regions. 3784 return false; 3785 } 3786 }; 3787 #endif // ASSERT 3788 3789 #if TASKQUEUE_STATS 3790 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) { 3791 st->print_raw_cr("GC Task Stats"); 3792 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); 3793 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); 3794 } 3795 3796 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const { 3797 print_taskqueue_stats_hdr(st); 3798 3799 TaskQueueStats totals; 3800 const int n = workers() != NULL ? workers()->total_workers() : 1; 3801 for (int i = 0; i < n; ++i) { 3802 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr(); 3803 totals += task_queue(i)->stats; 3804 } 3805 st->print_raw("tot "); totals.print(st); st->cr(); 3806 3807 DEBUG_ONLY(totals.verify()); 3808 } 3809 3810 void G1CollectedHeap::reset_taskqueue_stats() { 3811 const int n = workers() != NULL ? workers()->total_workers() : 1; 3812 for (int i = 0; i < n; ++i) { 3813 task_queue(i)->stats.reset(); 3814 } 3815 } 3816 #endif // TASKQUEUE_STATS 3817 3818 void G1CollectedHeap::log_gc_header() { 3819 if (!G1Log::fine()) { 3820 return; 3821 } 3822 3823 gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id()); 3824 3825 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause()) 3826 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)") 3827 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : ""); 3828 3829 gclog_or_tty->print("[%s", (const char*)gc_cause_str); 3830 } 3831 3832 void G1CollectedHeap::log_gc_footer(double pause_time_sec) { 3833 if (!G1Log::fine()) { 3834 return; 3835 } 3836 3837 if (G1Log::finer()) { 3838 if (evacuation_failed()) { 3839 gclog_or_tty->print(" (to-space exhausted)"); 3840 } 3841 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec); 3842 g1_policy()->phase_times()->note_gc_end(); 3843 g1_policy()->phase_times()->print(pause_time_sec); 3844 g1_policy()->print_detailed_heap_transition(); 3845 } else { 3846 if (evacuation_failed()) { 3847 gclog_or_tty->print("--"); 3848 } 3849 g1_policy()->print_heap_transition(); 3850 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec); 3851 } 3852 gclog_or_tty->flush(); 3853 } 3854 3855 bool 3856 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { 3857 assert_at_safepoint(true /* should_be_vm_thread */); 3858 guarantee(!is_gc_active(), "collection is not reentrant"); 3859 3860 if (GC_locker::check_active_before_gc()) { 3861 return false; 3862 } 3863 3864 _gc_timer_stw->register_gc_start(); 3865 3866 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start()); 3867 3868 SvcGCMarker sgcm(SvcGCMarker::MINOR); 3869 ResourceMark rm; 3870 3871 print_heap_before_gc(); 3872 trace_heap_before_gc(_gc_tracer_stw); 3873 3874 verify_region_sets_optional(); 3875 verify_dirty_young_regions(); 3876 3877 // This call will decide whether this pause is an initial-mark 3878 // pause. If it is, during_initial_mark_pause() will return true 3879 // for the duration of this pause. 3880 g1_policy()->decide_on_conc_mark_initiation(); 3881 3882 // We do not allow initial-mark to be piggy-backed on a mixed GC. 3883 assert(!g1_policy()->during_initial_mark_pause() || 3884 g1_policy()->gcs_are_young(), "sanity"); 3885 3886 // We also do not allow mixed GCs during marking. 3887 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity"); 3888 3889 // Record whether this pause is an initial mark. When the current 3890 // thread has completed its logging output and it's safe to signal 3891 // the CM thread, the flag's value in the policy has been reset. 3892 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause(); 3893 3894 // Inner scope for scope based logging, timers, and stats collection 3895 { 3896 EvacuationInfo evacuation_info; 3897 3898 if (g1_policy()->during_initial_mark_pause()) { 3899 // We are about to start a marking cycle, so we increment the 3900 // full collection counter. 3901 increment_old_marking_cycles_started(); 3902 register_concurrent_cycle_start(_gc_timer_stw->gc_start()); 3903 } 3904 3905 _gc_tracer_stw->report_yc_type(yc_type()); 3906 3907 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty); 3908 3909 int active_workers = (G1CollectedHeap::use_parallel_gc_threads() ? 3910 workers()->active_workers() : 1); 3911 double pause_start_sec = os::elapsedTime(); 3912 g1_policy()->phase_times()->note_gc_start(active_workers); 3913 log_gc_header(); 3914 3915 TraceCollectorStats tcs(g1mm()->incremental_collection_counters()); 3916 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause()); 3917 3918 // If the secondary_free_list is not empty, append it to the 3919 // free_list. No need to wait for the cleanup operation to finish; 3920 // the region allocation code will check the secondary_free_list 3921 // and wait if necessary. If the G1StressConcRegionFreeing flag is 3922 // set, skip this step so that the region allocation code has to 3923 // get entries from the secondary_free_list. 3924 if (!G1StressConcRegionFreeing) { 3925 append_secondary_free_list_if_not_empty_with_lock(); 3926 } 3927 3928 assert(check_young_list_well_formed(), "young list should be well formed"); 3929 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue), 3930 "sanity check"); 3931 3932 // Don't dynamically change the number of GC threads this early. A value of 3933 // 0 is used to indicate serial work. When parallel work is done, 3934 // it will be set. 3935 3936 { // Call to jvmpi::post_class_unload_events must occur outside of active GC 3937 IsGCActiveMark x; 3938 3939 gc_prologue(false); 3940 increment_total_collections(false /* full gc */); 3941 increment_gc_time_stamp(); 3942 3943 verify_before_gc(); 3944 3945 check_bitmaps("GC Start"); 3946 3947 COMPILER2_PRESENT(DerivedPointerTable::clear()); 3948 3949 // Please see comment in g1CollectedHeap.hpp and 3950 // G1CollectedHeap::ref_processing_init() to see how 3951 // reference processing currently works in G1. 3952 3953 // Enable discovery in the STW reference processor 3954 ref_processor_stw()->enable_discovery(true /*verify_disabled*/, 3955 true /*verify_no_refs*/); 3956 3957 { 3958 // We want to temporarily turn off discovery by the 3959 // CM ref processor, if necessary, and turn it back on 3960 // on again later if we do. Using a scoped 3961 // NoRefDiscovery object will do this. 3962 NoRefDiscovery no_cm_discovery(ref_processor_cm()); 3963 3964 // Forget the current alloc region (we might even choose it to be part 3965 // of the collection set!). 3966 _allocator->release_mutator_alloc_region(); 3967 3968 // We should call this after we retire the mutator alloc 3969 // region(s) so that all the ALLOC / RETIRE events are generated 3970 // before the start GC event. 3971 _hr_printer.start_gc(false /* full */, (size_t) total_collections()); 3972 3973 // This timing is only used by the ergonomics to handle our pause target. 3974 // It is unclear why this should not include the full pause. We will 3975 // investigate this in CR 7178365. 3976 // 3977 // Preserving the old comment here if that helps the investigation: 3978 // 3979 // The elapsed time induced by the start time below deliberately elides 3980 // the possible verification above. 3981 double sample_start_time_sec = os::elapsedTime(); 3982 3983 #if YOUNG_LIST_VERBOSE 3984 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:"); 3985 _young_list->print(); 3986 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 3987 #endif // YOUNG_LIST_VERBOSE 3988 3989 g1_policy()->record_collection_pause_start(sample_start_time_sec); 3990 3991 double scan_wait_start = os::elapsedTime(); 3992 // We have to wait until the CM threads finish scanning the 3993 // root regions as it's the only way to ensure that all the 3994 // objects on them have been correctly scanned before we start 3995 // moving them during the GC. 3996 bool waited = _cm->root_regions()->wait_until_scan_finished(); 3997 double wait_time_ms = 0.0; 3998 if (waited) { 3999 double scan_wait_end = os::elapsedTime(); 4000 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0; 4001 } 4002 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms); 4003 4004 #if YOUNG_LIST_VERBOSE 4005 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:"); 4006 _young_list->print(); 4007 #endif // YOUNG_LIST_VERBOSE 4008 4009 if (g1_policy()->during_initial_mark_pause()) { 4010 concurrent_mark()->checkpointRootsInitialPre(); 4011 } 4012 4013 #if YOUNG_LIST_VERBOSE 4014 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:"); 4015 _young_list->print(); 4016 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 4017 #endif // YOUNG_LIST_VERBOSE 4018 4019 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info); 4020 4021 register_humongous_regions_with_in_cset_fast_test(); 4022 4023 _cm->note_start_of_gc(); 4024 // We should not verify the per-thread SATB buffers given that 4025 // we have not filtered them yet (we'll do so during the 4026 // GC). We also call this after finalize_cset() to 4027 // ensure that the CSet has been finalized. 4028 _cm->verify_no_cset_oops(true /* verify_stacks */, 4029 true /* verify_enqueued_buffers */, 4030 false /* verify_thread_buffers */, 4031 true /* verify_fingers */); 4032 4033 if (_hr_printer.is_active()) { 4034 HeapRegion* hr = g1_policy()->collection_set(); 4035 while (hr != NULL) { 4036 _hr_printer.cset(hr); 4037 hr = hr->next_in_collection_set(); 4038 } 4039 } 4040 4041 #ifdef ASSERT 4042 VerifyCSetClosure cl; 4043 collection_set_iterate(&cl); 4044 #endif // ASSERT 4045 4046 setup_surviving_young_words(); 4047 4048 // Initialize the GC alloc regions. 4049 _allocator->init_gc_alloc_regions(evacuation_info); 4050 4051 // Actually do the work... 4052 evacuate_collection_set(evacuation_info); 4053 4054 // We do this to mainly verify the per-thread SATB buffers 4055 // (which have been filtered by now) since we didn't verify 4056 // them earlier. No point in re-checking the stacks / enqueued 4057 // buffers given that the CSet has not changed since last time 4058 // we checked. 4059 _cm->verify_no_cset_oops(false /* verify_stacks */, 4060 false /* verify_enqueued_buffers */, 4061 true /* verify_thread_buffers */, 4062 true /* verify_fingers */); 4063 4064 free_collection_set(g1_policy()->collection_set(), evacuation_info); 4065 4066 eagerly_reclaim_humongous_regions(); 4067 4068 g1_policy()->clear_collection_set(); 4069 4070 cleanup_surviving_young_words(); 4071 4072 // Start a new incremental collection set for the next pause. 4073 g1_policy()->start_incremental_cset_building(); 4074 4075 clear_cset_fast_test(); 4076 4077 _young_list->reset_sampled_info(); 4078 4079 // Don't check the whole heap at this point as the 4080 // GC alloc regions from this pause have been tagged 4081 // as survivors and moved on to the survivor list. 4082 // Survivor regions will fail the !is_young() check. 4083 assert(check_young_list_empty(false /* check_heap */), 4084 "young list should be empty"); 4085 4086 #if YOUNG_LIST_VERBOSE 4087 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:"); 4088 _young_list->print(); 4089 #endif // YOUNG_LIST_VERBOSE 4090 4091 g1_policy()->record_survivor_regions(_young_list->survivor_length(), 4092 _young_list->first_survivor_region(), 4093 _young_list->last_survivor_region()); 4094 4095 _young_list->reset_auxilary_lists(); 4096 4097 if (evacuation_failed()) { 4098 _allocator->set_used(recalculate_used()); 4099 uint n_queues = MAX2((int)ParallelGCThreads, 1); 4100 for (uint i = 0; i < n_queues; i++) { 4101 if (_evacuation_failed_info_array[i].has_failed()) { 4102 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]); 4103 } 4104 } 4105 } else { 4106 // The "used" of the the collection set have already been subtracted 4107 // when they were freed. Add in the bytes evacuated. 4108 _allocator->increase_used(g1_policy()->bytes_copied_during_gc()); 4109 } 4110 4111 if (g1_policy()->during_initial_mark_pause()) { 4112 // We have to do this before we notify the CM threads that 4113 // they can start working to make sure that all the 4114 // appropriate initialization is done on the CM object. 4115 concurrent_mark()->checkpointRootsInitialPost(); 4116 set_marking_started(); 4117 // Note that we don't actually trigger the CM thread at 4118 // this point. We do that later when we're sure that 4119 // the current thread has completed its logging output. 4120 } 4121 4122 allocate_dummy_regions(); 4123 4124 #if YOUNG_LIST_VERBOSE 4125 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:"); 4126 _young_list->print(); 4127 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 4128 #endif // YOUNG_LIST_VERBOSE 4129 4130 _allocator->init_mutator_alloc_region(); 4131 4132 { 4133 size_t expand_bytes = g1_policy()->expansion_amount(); 4134 if (expand_bytes > 0) { 4135 size_t bytes_before = capacity(); 4136 // No need for an ergo verbose message here, 4137 // expansion_amount() does this when it returns a value > 0. 4138 if (!expand(expand_bytes)) { 4139 // We failed to expand the heap. Cannot do anything about it. 4140 } 4141 } 4142 } 4143 4144 // We redo the verification but now wrt to the new CSet which 4145 // has just got initialized after the previous CSet was freed. 4146 _cm->verify_no_cset_oops(true /* verify_stacks */, 4147 true /* verify_enqueued_buffers */, 4148 true /* verify_thread_buffers */, 4149 true /* verify_fingers */); 4150 _cm->note_end_of_gc(); 4151 4152 // This timing is only used by the ergonomics to handle our pause target. 4153 // It is unclear why this should not include the full pause. We will 4154 // investigate this in CR 7178365. 4155 double sample_end_time_sec = os::elapsedTime(); 4156 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; 4157 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info); 4158 4159 MemoryService::track_memory_usage(); 4160 4161 // In prepare_for_verify() below we'll need to scan the deferred 4162 // update buffers to bring the RSets up-to-date if 4163 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning 4164 // the update buffers we'll probably need to scan cards on the 4165 // regions we just allocated to (i.e., the GC alloc 4166 // regions). However, during the last GC we called 4167 // set_saved_mark() on all the GC alloc regions, so card 4168 // scanning might skip the [saved_mark_word()...top()] area of 4169 // those regions (i.e., the area we allocated objects into 4170 // during the last GC). But it shouldn't. Given that 4171 // saved_mark_word() is conditional on whether the GC time stamp 4172 // on the region is current or not, by incrementing the GC time 4173 // stamp here we invalidate all the GC time stamps on all the 4174 // regions and saved_mark_word() will simply return top() for 4175 // all the regions. This is a nicer way of ensuring this rather 4176 // than iterating over the regions and fixing them. In fact, the 4177 // GC time stamp increment here also ensures that 4178 // saved_mark_word() will return top() between pauses, i.e., 4179 // during concurrent refinement. So we don't need the 4180 // is_gc_active() check to decided which top to use when 4181 // scanning cards (see CR 7039627). 4182 increment_gc_time_stamp(); 4183 4184 verify_after_gc(); 4185 check_bitmaps("GC End"); 4186 4187 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 4188 ref_processor_stw()->verify_no_references_recorded(); 4189 4190 // CM reference discovery will be re-enabled if necessary. 4191 } 4192 4193 // We should do this after we potentially expand the heap so 4194 // that all the COMMIT events are generated before the end GC 4195 // event, and after we retire the GC alloc regions so that all 4196 // RETIRE events are generated before the end GC event. 4197 _hr_printer.end_gc(false /* full */, (size_t) total_collections()); 4198 4199 #ifdef TRACESPINNING 4200 ParallelTaskTerminator::print_termination_counts(); 4201 #endif 4202 4203 gc_epilogue(false); 4204 } 4205 4206 // Print the remainder of the GC log output. 4207 log_gc_footer(os::elapsedTime() - pause_start_sec); 4208 4209 // It is not yet to safe to tell the concurrent mark to 4210 // start as we have some optional output below. We don't want the 4211 // output from the concurrent mark thread interfering with this 4212 // logging output either. 4213 4214 _hrm.verify_optional(); 4215 verify_region_sets_optional(); 4216 4217 TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats()); 4218 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); 4219 4220 print_heap_after_gc(); 4221 trace_heap_after_gc(_gc_tracer_stw); 4222 4223 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 4224 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 4225 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 4226 // before any GC notifications are raised. 4227 g1mm()->update_sizes(); 4228 4229 _gc_tracer_stw->report_evacuation_info(&evacuation_info); 4230 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold()); 4231 _gc_timer_stw->register_gc_end(); 4232 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions()); 4233 } 4234 // It should now be safe to tell the concurrent mark thread to start 4235 // without its logging output interfering with the logging output 4236 // that came from the pause. 4237 4238 if (should_start_conc_mark) { 4239 // CAUTION: after the doConcurrentMark() call below, 4240 // the concurrent marking thread(s) could be running 4241 // concurrently with us. Make sure that anything after 4242 // this point does not assume that we are the only GC thread 4243 // running. Note: of course, the actual marking work will 4244 // not start until the safepoint itself is released in 4245 // SuspendibleThreadSet::desynchronize(). 4246 doConcurrentMark(); 4247 } 4248 4249 return true; 4250 } 4251 4252 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose) 4253 { 4254 size_t gclab_word_size; 4255 switch (purpose) { 4256 case GCAllocForSurvived: 4257 gclab_word_size = _survivor_plab_stats.desired_plab_sz(); 4258 break; 4259 case GCAllocForTenured: 4260 gclab_word_size = _old_plab_stats.desired_plab_sz(); 4261 break; 4262 default: 4263 assert(false, "unknown GCAllocPurpose"); 4264 gclab_word_size = _old_plab_stats.desired_plab_sz(); 4265 break; 4266 } 4267 4268 // Prevent humongous PLAB sizes for two reasons: 4269 // * PLABs are allocated using a similar paths as oops, but should 4270 // never be in a humongous region 4271 // * Allowing humongous PLABs needlessly churns the region free lists 4272 return MIN2(_humongous_object_threshold_in_words, gclab_word_size); 4273 } 4274 4275 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) { 4276 _drain_in_progress = false; 4277 set_evac_failure_closure(cl); 4278 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true); 4279 } 4280 4281 void G1CollectedHeap::finalize_for_evac_failure() { 4282 assert(_evac_failure_scan_stack != NULL && 4283 _evac_failure_scan_stack->length() == 0, 4284 "Postcondition"); 4285 assert(!_drain_in_progress, "Postcondition"); 4286 delete _evac_failure_scan_stack; 4287 _evac_failure_scan_stack = NULL; 4288 } 4289 4290 void G1CollectedHeap::remove_self_forwarding_pointers() { 4291 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity"); 4292 4293 double remove_self_forwards_start = os::elapsedTime(); 4294 4295 G1ParRemoveSelfForwardPtrsTask rsfp_task(this); 4296 4297 if (G1CollectedHeap::use_parallel_gc_threads()) { 4298 set_par_threads(); 4299 workers()->run_task(&rsfp_task); 4300 set_par_threads(0); 4301 } else { 4302 rsfp_task.work(0); 4303 } 4304 4305 assert(check_cset_heap_region_claim_values(HeapRegion::ParEvacFailureClaimValue), "sanity"); 4306 4307 // Reset the claim values in the regions in the collection set. 4308 reset_cset_heap_region_claim_values(); 4309 4310 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity"); 4311 4312 // Now restore saved marks, if any. 4313 assert(_objs_with_preserved_marks.size() == 4314 _preserved_marks_of_objs.size(), "Both or none."); 4315 while (!_objs_with_preserved_marks.is_empty()) { 4316 oop obj = _objs_with_preserved_marks.pop(); 4317 markOop m = _preserved_marks_of_objs.pop(); 4318 obj->set_mark(m); 4319 } 4320 _objs_with_preserved_marks.clear(true); 4321 _preserved_marks_of_objs.clear(true); 4322 4323 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0); 4324 } 4325 4326 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) { 4327 _evac_failure_scan_stack->push(obj); 4328 } 4329 4330 void G1CollectedHeap::drain_evac_failure_scan_stack() { 4331 assert(_evac_failure_scan_stack != NULL, "precondition"); 4332 4333 while (_evac_failure_scan_stack->length() > 0) { 4334 oop obj = _evac_failure_scan_stack->pop(); 4335 _evac_failure_closure->set_region(heap_region_containing(obj)); 4336 obj->oop_iterate_backwards(_evac_failure_closure); 4337 } 4338 } 4339 4340 oop 4341 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state, 4342 oop old) { 4343 assert(obj_in_cs(old), 4344 err_msg("obj: "PTR_FORMAT" should still be in the CSet", 4345 (HeapWord*) old)); 4346 markOop m = old->mark(); 4347 oop forward_ptr = old->forward_to_atomic(old); 4348 if (forward_ptr == NULL) { 4349 // Forward-to-self succeeded. 4350 assert(_par_scan_state != NULL, "par scan state"); 4351 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure(); 4352 uint queue_num = _par_scan_state->queue_num(); 4353 4354 _evacuation_failed = true; 4355 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size()); 4356 if (_evac_failure_closure != cl) { 4357 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag); 4358 assert(!_drain_in_progress, 4359 "Should only be true while someone holds the lock."); 4360 // Set the global evac-failure closure to the current thread's. 4361 assert(_evac_failure_closure == NULL, "Or locking has failed."); 4362 set_evac_failure_closure(cl); 4363 // Now do the common part. 4364 handle_evacuation_failure_common(old, m); 4365 // Reset to NULL. 4366 set_evac_failure_closure(NULL); 4367 } else { 4368 // The lock is already held, and this is recursive. 4369 assert(_drain_in_progress, "This should only be the recursive case."); 4370 handle_evacuation_failure_common(old, m); 4371 } 4372 return old; 4373 } else { 4374 // Forward-to-self failed. Either someone else managed to allocate 4375 // space for this object (old != forward_ptr) or they beat us in 4376 // self-forwarding it (old == forward_ptr). 4377 assert(old == forward_ptr || !obj_in_cs(forward_ptr), 4378 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" " 4379 "should not be in the CSet", 4380 (HeapWord*) old, (HeapWord*) forward_ptr)); 4381 return forward_ptr; 4382 } 4383 } 4384 4385 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) { 4386 preserve_mark_if_necessary(old, m); 4387 4388 HeapRegion* r = heap_region_containing(old); 4389 if (!r->evacuation_failed()) { 4390 r->set_evacuation_failed(true); 4391 _hr_printer.evac_failure(r); 4392 } 4393 4394 push_on_evac_failure_scan_stack(old); 4395 4396 if (!_drain_in_progress) { 4397 // prevent recursion in copy_to_survivor_space() 4398 _drain_in_progress = true; 4399 drain_evac_failure_scan_stack(); 4400 _drain_in_progress = false; 4401 } 4402 } 4403 4404 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) { 4405 assert(evacuation_failed(), "Oversaving!"); 4406 // We want to call the "for_promotion_failure" version only in the 4407 // case of a promotion failure. 4408 if (m->must_be_preserved_for_promotion_failure(obj)) { 4409 _objs_with_preserved_marks.push(obj); 4410 _preserved_marks_of_objs.push(m); 4411 } 4412 } 4413 4414 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose, 4415 size_t word_size, 4416 AllocationContext_t context) { 4417 if (purpose == GCAllocForSurvived) { 4418 HeapWord* result = survivor_attempt_allocation(word_size, context); 4419 if (result != NULL) { 4420 return result; 4421 } else { 4422 // Let's try to allocate in the old gen in case we can fit the 4423 // object there. 4424 return old_attempt_allocation(word_size, context); 4425 } 4426 } else { 4427 assert(purpose == GCAllocForTenured, "sanity"); 4428 HeapWord* result = old_attempt_allocation(word_size, context); 4429 if (result != NULL) { 4430 return result; 4431 } else { 4432 // Let's try to allocate in the survivors in case we can fit the 4433 // object there. 4434 return survivor_attempt_allocation(word_size, context); 4435 } 4436 } 4437 4438 ShouldNotReachHere(); 4439 // Trying to keep some compilers happy. 4440 return NULL; 4441 } 4442 4443 void G1ParCopyHelper::mark_object(oop obj) { 4444 assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet"); 4445 4446 // We know that the object is not moving so it's safe to read its size. 4447 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id); 4448 } 4449 4450 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) { 4451 assert(from_obj->is_forwarded(), "from obj should be forwarded"); 4452 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee"); 4453 assert(from_obj != to_obj, "should not be self-forwarded"); 4454 4455 assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet"); 4456 assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet"); 4457 4458 // The object might be in the process of being copied by another 4459 // worker so we cannot trust that its to-space image is 4460 // well-formed. So we have to read its size from its from-space 4461 // image which we know should not be changing. 4462 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id); 4463 } 4464 4465 template <class T> 4466 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) { 4467 if (_g1->heap_region_containing_raw(new_obj)->is_young()) { 4468 _scanned_klass->record_modified_oops(); 4469 } 4470 } 4471 4472 template <G1Barrier barrier, G1Mark do_mark_object> 4473 template <class T> 4474 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) { 4475 T heap_oop = oopDesc::load_heap_oop(p); 4476 4477 if (oopDesc::is_null(heap_oop)) { 4478 return; 4479 } 4480 4481 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 4482 4483 assert(_worker_id == _par_scan_state->queue_num(), "sanity"); 4484 4485 G1CollectedHeap::in_cset_state_t state = _g1->in_cset_state(obj); 4486 4487 if (state == G1CollectedHeap::InCSet) { 4488 oop forwardee; 4489 if (obj->is_forwarded()) { 4490 forwardee = obj->forwardee(); 4491 } else { 4492 forwardee = _par_scan_state->copy_to_survivor_space(obj); 4493 } 4494 assert(forwardee != NULL, "forwardee should not be NULL"); 4495 oopDesc::encode_store_heap_oop(p, forwardee); 4496 if (do_mark_object != G1MarkNone && forwardee != obj) { 4497 // If the object is self-forwarded we don't need to explicitly 4498 // mark it, the evacuation failure protocol will do so. 4499 mark_forwarded_object(obj, forwardee); 4500 } 4501 4502 if (barrier == G1BarrierKlass) { 4503 do_klass_barrier(p, forwardee); 4504 } 4505 } else { 4506 if (state == G1CollectedHeap::IsHumongous) { 4507 _g1->set_humongous_is_live(obj); 4508 } 4509 // The object is not in collection set. If we're a root scanning 4510 // closure during an initial mark pause then attempt to mark the object. 4511 if (do_mark_object == G1MarkFromRoot) { 4512 mark_object(obj); 4513 } 4514 } 4515 4516 if (barrier == G1BarrierEvac) { 4517 _par_scan_state->update_rs(_from, p, _worker_id); 4518 } 4519 } 4520 4521 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(oop* p); 4522 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(narrowOop* p); 4523 4524 class G1ParEvacuateFollowersClosure : public VoidClosure { 4525 protected: 4526 G1CollectedHeap* _g1h; 4527 G1ParScanThreadState* _par_scan_state; 4528 RefToScanQueueSet* _queues; 4529 ParallelTaskTerminator* _terminator; 4530 4531 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 4532 RefToScanQueueSet* queues() { return _queues; } 4533 ParallelTaskTerminator* terminator() { return _terminator; } 4534 4535 public: 4536 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h, 4537 G1ParScanThreadState* par_scan_state, 4538 RefToScanQueueSet* queues, 4539 ParallelTaskTerminator* terminator) 4540 : _g1h(g1h), _par_scan_state(par_scan_state), 4541 _queues(queues), _terminator(terminator) {} 4542 4543 void do_void(); 4544 4545 private: 4546 inline bool offer_termination(); 4547 }; 4548 4549 bool G1ParEvacuateFollowersClosure::offer_termination() { 4550 G1ParScanThreadState* const pss = par_scan_state(); 4551 pss->start_term_time(); 4552 const bool res = terminator()->offer_termination(); 4553 pss->end_term_time(); 4554 return res; 4555 } 4556 4557 void G1ParEvacuateFollowersClosure::do_void() { 4558 G1ParScanThreadState* const pss = par_scan_state(); 4559 pss->trim_queue(); 4560 do { 4561 pss->steal_and_trim_queue(queues()); 4562 } while (!offer_termination()); 4563 } 4564 4565 class G1KlassScanClosure : public KlassClosure { 4566 G1ParCopyHelper* _closure; 4567 bool _process_only_dirty; 4568 int _count; 4569 public: 4570 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty) 4571 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {} 4572 void do_klass(Klass* klass) { 4573 // If the klass has not been dirtied we know that there's 4574 // no references into the young gen and we can skip it. 4575 if (!_process_only_dirty || klass->has_modified_oops()) { 4576 // Clean the klass since we're going to scavenge all the metadata. 4577 klass->clear_modified_oops(); 4578 4579 // Tell the closure that this klass is the Klass to scavenge 4580 // and is the one to dirty if oops are left pointing into the young gen. 4581 _closure->set_scanned_klass(klass); 4582 4583 klass->oops_do(_closure); 4584 4585 _closure->set_scanned_klass(NULL); 4586 } 4587 _count++; 4588 } 4589 }; 4590 4591 class G1CodeBlobClosure : public CodeBlobClosure { 4592 class HeapRegionGatheringOopClosure : public OopClosure { 4593 G1CollectedHeap* _g1h; 4594 OopClosure* _work; 4595 nmethod* _nm; 4596 4597 template <typename T> 4598 void do_oop_work(T* p) { 4599 _work->do_oop(p); 4600 T oop_or_narrowoop = oopDesc::load_heap_oop(p); 4601 if (!oopDesc::is_null(oop_or_narrowoop)) { 4602 oop o = oopDesc::decode_heap_oop_not_null(oop_or_narrowoop); 4603 HeapRegion* hr = _g1h->heap_region_containing_raw(o); 4604 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"); 4605 hr->add_strong_code_root(_nm); 4606 } 4607 } 4608 4609 public: 4610 HeapRegionGatheringOopClosure(OopClosure* oc) : _g1h(G1CollectedHeap::heap()), _work(oc), _nm(NULL) {} 4611 4612 void do_oop(oop* o) { 4613 do_oop_work(o); 4614 } 4615 4616 void do_oop(narrowOop* o) { 4617 do_oop_work(o); 4618 } 4619 4620 void set_nm(nmethod* nm) { 4621 _nm = nm; 4622 } 4623 }; 4624 4625 HeapRegionGatheringOopClosure _oc; 4626 public: 4627 G1CodeBlobClosure(OopClosure* oc) : _oc(oc) {} 4628 4629 void do_code_blob(CodeBlob* cb) { 4630 nmethod* nm = cb->as_nmethod_or_null(); 4631 if (nm != NULL) { 4632 if (!nm->test_set_oops_do_mark()) { 4633 _oc.set_nm(nm); 4634 nm->oops_do(&_oc); 4635 nm->fix_oop_relocations(); 4636 } 4637 } 4638 } 4639 }; 4640 4641 class G1ParTask : public AbstractGangTask { 4642 protected: 4643 G1CollectedHeap* _g1h; 4644 RefToScanQueueSet *_queues; 4645 ParallelTaskTerminator _terminator; 4646 uint _n_workers; 4647 4648 Mutex _stats_lock; 4649 Mutex* stats_lock() { return &_stats_lock; } 4650 4651 public: 4652 G1ParTask(G1CollectedHeap* g1h, RefToScanQueueSet *task_queues) 4653 : AbstractGangTask("G1 collection"), 4654 _g1h(g1h), 4655 _queues(task_queues), 4656 _terminator(0, _queues), 4657 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true) 4658 {} 4659 4660 RefToScanQueueSet* queues() { return _queues; } 4661 4662 RefToScanQueue *work_queue(int i) { 4663 return queues()->queue(i); 4664 } 4665 4666 ParallelTaskTerminator* terminator() { return &_terminator; } 4667 4668 virtual void set_for_termination(int active_workers) { 4669 // This task calls set_n_termination() in par_non_clean_card_iterate_work() 4670 // in the young space (_par_seq_tasks) in the G1 heap 4671 // for SequentialSubTasksDone. 4672 // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap 4673 // both of which need setting by set_n_termination(). 4674 _g1h->SharedHeap::set_n_termination(active_workers); 4675 _g1h->set_n_termination(active_workers); 4676 terminator()->reset_for_reuse(active_workers); 4677 _n_workers = active_workers; 4678 } 4679 4680 // Helps out with CLD processing. 4681 // 4682 // During InitialMark we need to: 4683 // 1) Scavenge all CLDs for the young GC. 4684 // 2) Mark all objects directly reachable from strong CLDs. 4685 template <G1Mark do_mark_object> 4686 class G1CLDClosure : public CLDClosure { 4687 G1ParCopyClosure<G1BarrierNone, do_mark_object>* _oop_closure; 4688 G1ParCopyClosure<G1BarrierKlass, do_mark_object> _oop_in_klass_closure; 4689 G1KlassScanClosure _klass_in_cld_closure; 4690 bool _claim; 4691 4692 public: 4693 G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure, 4694 bool only_young, bool claim) 4695 : _oop_closure(oop_closure), 4696 _oop_in_klass_closure(oop_closure->g1(), 4697 oop_closure->pss(), 4698 oop_closure->rp()), 4699 _klass_in_cld_closure(&_oop_in_klass_closure, only_young), 4700 _claim(claim) { 4701 4702 } 4703 4704 void do_cld(ClassLoaderData* cld) { 4705 cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim); 4706 } 4707 }; 4708 4709 void work(uint worker_id) { 4710 if (worker_id >= _n_workers) return; // no work needed this round 4711 4712 double start_time_ms = os::elapsedTime() * 1000.0; 4713 _g1h->g1_policy()->phase_times()->record_gc_worker_start_time(worker_id, start_time_ms); 4714 4715 { 4716 ResourceMark rm; 4717 HandleMark hm; 4718 4719 ReferenceProcessor* rp = _g1h->ref_processor_stw(); 4720 4721 G1ParScanThreadState pss(_g1h, worker_id, rp); 4722 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp); 4723 4724 pss.set_evac_failure_closure(&evac_failure_cl); 4725 4726 bool only_young = _g1h->g1_policy()->gcs_are_young(); 4727 4728 // Non-IM young GC. 4729 G1ParCopyClosure<G1BarrierNone, G1MarkNone> scan_only_root_cl(_g1h, &pss, rp); 4730 G1CLDClosure<G1MarkNone> scan_only_cld_cl(&scan_only_root_cl, 4731 only_young, // Only process dirty klasses. 4732 false); // No need to claim CLDs. 4733 // IM young GC. 4734 // Strong roots closures. 4735 G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot> scan_mark_root_cl(_g1h, &pss, rp); 4736 G1CLDClosure<G1MarkFromRoot> scan_mark_cld_cl(&scan_mark_root_cl, 4737 false, // Process all klasses. 4738 true); // Need to claim CLDs. 4739 // Weak roots closures. 4740 G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, &pss, rp); 4741 G1CLDClosure<G1MarkPromotedFromRoot> scan_mark_weak_cld_cl(&scan_mark_weak_root_cl, 4742 false, // Process all klasses. 4743 true); // Need to claim CLDs. 4744 4745 G1CodeBlobClosure scan_only_code_cl(&scan_only_root_cl); 4746 G1CodeBlobClosure scan_mark_code_cl(&scan_mark_root_cl); 4747 // IM Weak code roots are handled later. 4748 4749 OopClosure* strong_root_cl; 4750 OopClosure* weak_root_cl; 4751 CLDClosure* strong_cld_cl; 4752 CLDClosure* weak_cld_cl; 4753 CodeBlobClosure* strong_code_cl; 4754 4755 if (_g1h->g1_policy()->during_initial_mark_pause()) { 4756 // We also need to mark copied objects. 4757 strong_root_cl = &scan_mark_root_cl; 4758 strong_cld_cl = &scan_mark_cld_cl; 4759 strong_code_cl = &scan_mark_code_cl; 4760 if (ClassUnloadingWithConcurrentMark) { 4761 weak_root_cl = &scan_mark_weak_root_cl; 4762 weak_cld_cl = &scan_mark_weak_cld_cl; 4763 } else { 4764 weak_root_cl = &scan_mark_root_cl; 4765 weak_cld_cl = &scan_mark_cld_cl; 4766 } 4767 } else { 4768 strong_root_cl = &scan_only_root_cl; 4769 weak_root_cl = &scan_only_root_cl; 4770 strong_cld_cl = &scan_only_cld_cl; 4771 weak_cld_cl = &scan_only_cld_cl; 4772 strong_code_cl = &scan_only_code_cl; 4773 } 4774 4775 4776 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss); 4777 4778 pss.start_strong_roots(); 4779 _g1h->g1_process_roots(strong_root_cl, 4780 weak_root_cl, 4781 &push_heap_rs_cl, 4782 strong_cld_cl, 4783 weak_cld_cl, 4784 strong_code_cl, 4785 worker_id); 4786 4787 pss.end_strong_roots(); 4788 4789 { 4790 double start = os::elapsedTime(); 4791 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator); 4792 evac.do_void(); 4793 double elapsed_ms = (os::elapsedTime()-start)*1000.0; 4794 double term_ms = pss.term_time()*1000.0; 4795 _g1h->g1_policy()->phase_times()->add_obj_copy_time(worker_id, elapsed_ms-term_ms); 4796 _g1h->g1_policy()->phase_times()->record_termination(worker_id, term_ms, pss.term_attempts()); 4797 } 4798 _g1h->g1_policy()->record_thread_age_table(pss.age_table()); 4799 _g1h->update_surviving_young_words(pss.surviving_young_words()+1); 4800 4801 if (PrintTerminationStats) { 4802 MutexLocker x(stats_lock()); 4803 pss.print_termination_stats(worker_id); 4804 } 4805 4806 assert(pss.queue_is_empty(), "should be empty"); 4807 4808 // Close the inner scope so that the ResourceMark and HandleMark 4809 // destructors are executed here and are included as part of the 4810 // "GC Worker Time". 4811 } 4812 4813 double end_time_ms = os::elapsedTime() * 1000.0; 4814 _g1h->g1_policy()->phase_times()->record_gc_worker_end_time(worker_id, end_time_ms); 4815 } 4816 }; 4817 4818 // *** Common G1 Evacuation Stuff 4819 4820 // This method is run in a GC worker. 4821 4822 void 4823 G1CollectedHeap:: 4824 g1_process_roots(OopClosure* scan_non_heap_roots, 4825 OopClosure* scan_non_heap_weak_roots, 4826 OopsInHeapRegionClosure* scan_rs, 4827 CLDClosure* scan_strong_clds, 4828 CLDClosure* scan_weak_clds, 4829 CodeBlobClosure* scan_strong_code, 4830 uint worker_i) { 4831 4832 // First scan the shared roots. 4833 double ext_roots_start = os::elapsedTime(); 4834 double closure_app_time_sec = 0.0; 4835 4836 bool during_im = _g1h->g1_policy()->during_initial_mark_pause(); 4837 bool trace_metadata = during_im && ClassUnloadingWithConcurrentMark; 4838 4839 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots); 4840 BufferingOopClosure buf_scan_non_heap_weak_roots(scan_non_heap_weak_roots); 4841 4842 process_roots(false, // no scoping; this is parallel code 4843 SharedHeap::SO_None, 4844 &buf_scan_non_heap_roots, 4845 &buf_scan_non_heap_weak_roots, 4846 scan_strong_clds, 4847 // Unloading Initial Marks handle the weak CLDs separately. 4848 (trace_metadata ? NULL : scan_weak_clds), 4849 scan_strong_code); 4850 4851 // Now the CM ref_processor roots. 4852 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) { 4853 // We need to treat the discovered reference lists of the 4854 // concurrent mark ref processor as roots and keep entries 4855 // (which are added by the marking threads) on them live 4856 // until they can be processed at the end of marking. 4857 ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots); 4858 } 4859 4860 if (trace_metadata) { 4861 // Barrier to make sure all workers passed 4862 // the strong CLD and strong nmethods phases. 4863 active_strong_roots_scope()->wait_until_all_workers_done_with_threads(n_par_threads()); 4864 4865 // Now take the complement of the strong CLDs. 4866 ClassLoaderDataGraph::roots_cld_do(NULL, scan_weak_clds); 4867 } 4868 4869 // Finish up any enqueued closure apps (attributed as object copy time). 4870 buf_scan_non_heap_roots.done(); 4871 buf_scan_non_heap_weak_roots.done(); 4872 4873 double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds() 4874 + buf_scan_non_heap_weak_roots.closure_app_seconds(); 4875 4876 g1_policy()->phase_times()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0); 4877 4878 double ext_root_time_ms = 4879 ((os::elapsedTime() - ext_roots_start) - obj_copy_time_sec) * 1000.0; 4880 4881 g1_policy()->phase_times()->record_ext_root_scan_time(worker_i, ext_root_time_ms); 4882 4883 // During conc marking we have to filter the per-thread SATB buffers 4884 // to make sure we remove any oops into the CSet (which will show up 4885 // as implicitly live). 4886 double satb_filtering_ms = 0.0; 4887 if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers)) { 4888 if (mark_in_progress()) { 4889 double satb_filter_start = os::elapsedTime(); 4890 4891 JavaThread::satb_mark_queue_set().filter_thread_buffers(); 4892 4893 satb_filtering_ms = (os::elapsedTime() - satb_filter_start) * 1000.0; 4894 } 4895 } 4896 g1_policy()->phase_times()->record_satb_filtering_time(worker_i, satb_filtering_ms); 4897 4898 // Now scan the complement of the collection set. 4899 G1CodeBlobClosure scavenge_cs_nmethods(scan_non_heap_weak_roots); 4900 4901 g1_rem_set()->oops_into_collection_set_do(scan_rs, &scavenge_cs_nmethods, worker_i); 4902 4903 _process_strong_tasks->all_tasks_completed(); 4904 } 4905 4906 class G1StringSymbolTableUnlinkTask : public AbstractGangTask { 4907 private: 4908 BoolObjectClosure* _is_alive; 4909 int _initial_string_table_size; 4910 int _initial_symbol_table_size; 4911 4912 bool _process_strings; 4913 int _strings_processed; 4914 int _strings_removed; 4915 4916 bool _process_symbols; 4917 int _symbols_processed; 4918 int _symbols_removed; 4919 4920 bool _do_in_parallel; 4921 public: 4922 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) : 4923 AbstractGangTask("String/Symbol Unlinking"), 4924 _is_alive(is_alive), 4925 _do_in_parallel(G1CollectedHeap::use_parallel_gc_threads()), 4926 _process_strings(process_strings), _strings_processed(0), _strings_removed(0), 4927 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) { 4928 4929 _initial_string_table_size = StringTable::the_table()->table_size(); 4930 _initial_symbol_table_size = SymbolTable::the_table()->table_size(); 4931 if (process_strings) { 4932 StringTable::clear_parallel_claimed_index(); 4933 } 4934 if (process_symbols) { 4935 SymbolTable::clear_parallel_claimed_index(); 4936 } 4937 } 4938 4939 ~G1StringSymbolTableUnlinkTask() { 4940 guarantee(!_process_strings || !_do_in_parallel || StringTable::parallel_claimed_index() >= _initial_string_table_size, 4941 err_msg("claim value %d after unlink less than initial string table size %d", 4942 StringTable::parallel_claimed_index(), _initial_string_table_size)); 4943 guarantee(!_process_symbols || !_do_in_parallel || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size, 4944 err_msg("claim value %d after unlink less than initial symbol table size %d", 4945 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size)); 4946 4947 if (G1TraceStringSymbolTableScrubbing) { 4948 gclog_or_tty->print_cr("Cleaned string and symbol table, " 4949 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, " 4950 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed", 4951 strings_processed(), strings_removed(), 4952 symbols_processed(), symbols_removed()); 4953 } 4954 } 4955 4956 void work(uint worker_id) { 4957 if (_do_in_parallel) { 4958 int strings_processed = 0; 4959 int strings_removed = 0; 4960 int symbols_processed = 0; 4961 int symbols_removed = 0; 4962 if (_process_strings) { 4963 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed); 4964 Atomic::add(strings_processed, &_strings_processed); 4965 Atomic::add(strings_removed, &_strings_removed); 4966 } 4967 if (_process_symbols) { 4968 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed); 4969 Atomic::add(symbols_processed, &_symbols_processed); 4970 Atomic::add(symbols_removed, &_symbols_removed); 4971 } 4972 } else { 4973 if (_process_strings) { 4974 StringTable::unlink(_is_alive, &_strings_processed, &_strings_removed); 4975 } 4976 if (_process_symbols) { 4977 SymbolTable::unlink(&_symbols_processed, &_symbols_removed); 4978 } 4979 } 4980 } 4981 4982 size_t strings_processed() const { return (size_t)_strings_processed; } 4983 size_t strings_removed() const { return (size_t)_strings_removed; } 4984 4985 size_t symbols_processed() const { return (size_t)_symbols_processed; } 4986 size_t symbols_removed() const { return (size_t)_symbols_removed; } 4987 }; 4988 4989 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC { 4990 private: 4991 static Monitor* _lock; 4992 4993 BoolObjectClosure* const _is_alive; 4994 const bool _unloading_occurred; 4995 const uint _num_workers; 4996 4997 // Variables used to claim nmethods. 4998 nmethod* _first_nmethod; 4999 volatile nmethod* _claimed_nmethod; 5000 5001 // The list of nmethods that need to be processed by the second pass. 5002 volatile nmethod* _postponed_list; 5003 volatile uint _num_entered_barrier; 5004 5005 public: 5006 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) : 5007 _is_alive(is_alive), 5008 _unloading_occurred(unloading_occurred), 5009 _num_workers(num_workers), 5010 _first_nmethod(NULL), 5011 _claimed_nmethod(NULL), 5012 _postponed_list(NULL), 5013 _num_entered_barrier(0) 5014 { 5015 nmethod::increase_unloading_clock(); 5016 _first_nmethod = CodeCache::alive_nmethod(CodeCache::first()); 5017 _claimed_nmethod = (volatile nmethod*)_first_nmethod; 5018 } 5019 5020 ~G1CodeCacheUnloadingTask() { 5021 CodeCache::verify_clean_inline_caches(); 5022 5023 CodeCache::set_needs_cache_clean(false); 5024 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be"); 5025 5026 CodeCache::verify_icholder_relocations(); 5027 } 5028 5029 private: 5030 void add_to_postponed_list(nmethod* nm) { 5031 nmethod* old; 5032 do { 5033 old = (nmethod*)_postponed_list; 5034 nm->set_unloading_next(old); 5035 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old); 5036 } 5037 5038 void clean_nmethod(nmethod* nm) { 5039 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred); 5040 5041 if (postponed) { 5042 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet. 5043 add_to_postponed_list(nm); 5044 } 5045 5046 // Mark that this thread has been cleaned/unloaded. 5047 // After this call, it will be safe to ask if this nmethod was unloaded or not. 5048 nm->set_unloading_clock(nmethod::global_unloading_clock()); 5049 } 5050 5051 void clean_nmethod_postponed(nmethod* nm) { 5052 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred); 5053 } 5054 5055 static const int MaxClaimNmethods = 16; 5056 5057 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) { 5058 nmethod* first; 5059 nmethod* last; 5060 5061 do { 5062 *num_claimed_nmethods = 0; 5063 5064 first = last = (nmethod*)_claimed_nmethod; 5065 5066 if (first != NULL) { 5067 for (int i = 0; i < MaxClaimNmethods; i++) { 5068 last = CodeCache::alive_nmethod(CodeCache::next(last)); 5069 5070 if (last == NULL) { 5071 break; 5072 } 5073 5074 claimed_nmethods[i] = last; 5075 (*num_claimed_nmethods)++; 5076 } 5077 } 5078 5079 } while ((nmethod*)Atomic::cmpxchg_ptr(last, &_claimed_nmethod, first) != first); 5080 } 5081 5082 nmethod* claim_postponed_nmethod() { 5083 nmethod* claim; 5084 nmethod* next; 5085 5086 do { 5087 claim = (nmethod*)_postponed_list; 5088 if (claim == NULL) { 5089 return NULL; 5090 } 5091 5092 next = claim->unloading_next(); 5093 5094 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim); 5095 5096 return claim; 5097 } 5098 5099 public: 5100 // Mark that we're done with the first pass of nmethod cleaning. 5101 void barrier_mark(uint worker_id) { 5102 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 5103 _num_entered_barrier++; 5104 if (_num_entered_barrier == _num_workers) { 5105 ml.notify_all(); 5106 } 5107 } 5108 5109 // See if we have to wait for the other workers to 5110 // finish their first-pass nmethod cleaning work. 5111 void barrier_wait(uint worker_id) { 5112 if (_num_entered_barrier < _num_workers) { 5113 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 5114 while (_num_entered_barrier < _num_workers) { 5115 ml.wait(Mutex::_no_safepoint_check_flag, 0, false); 5116 } 5117 } 5118 } 5119 5120 // Cleaning and unloading of nmethods. Some work has to be postponed 5121 // to the second pass, when we know which nmethods survive. 5122 void work_first_pass(uint worker_id) { 5123 // The first nmethods is claimed by the first worker. 5124 if (worker_id == 0 && _first_nmethod != NULL) { 5125 clean_nmethod(_first_nmethod); 5126 _first_nmethod = NULL; 5127 } 5128 5129 int num_claimed_nmethods; 5130 nmethod* claimed_nmethods[MaxClaimNmethods]; 5131 5132 while (true) { 5133 claim_nmethods(claimed_nmethods, &num_claimed_nmethods); 5134 5135 if (num_claimed_nmethods == 0) { 5136 break; 5137 } 5138 5139 for (int i = 0; i < num_claimed_nmethods; i++) { 5140 clean_nmethod(claimed_nmethods[i]); 5141 } 5142 } 5143 } 5144 5145 void work_second_pass(uint worker_id) { 5146 nmethod* nm; 5147 // Take care of postponed nmethods. 5148 while ((nm = claim_postponed_nmethod()) != NULL) { 5149 clean_nmethod_postponed(nm); 5150 } 5151 } 5152 }; 5153 5154 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock"); 5155 5156 class G1KlassCleaningTask : public StackObj { 5157 BoolObjectClosure* _is_alive; 5158 volatile jint _clean_klass_tree_claimed; 5159 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator; 5160 5161 public: 5162 G1KlassCleaningTask(BoolObjectClosure* is_alive) : 5163 _is_alive(is_alive), 5164 _clean_klass_tree_claimed(0), 5165 _klass_iterator() { 5166 } 5167 5168 private: 5169 bool claim_clean_klass_tree_task() { 5170 if (_clean_klass_tree_claimed) { 5171 return false; 5172 } 5173 5174 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0; 5175 } 5176 5177 InstanceKlass* claim_next_klass() { 5178 Klass* klass; 5179 do { 5180 klass =_klass_iterator.next_klass(); 5181 } while (klass != NULL && !klass->oop_is_instance()); 5182 5183 return (InstanceKlass*)klass; 5184 } 5185 5186 public: 5187 5188 void clean_klass(InstanceKlass* ik) { 5189 ik->clean_implementors_list(_is_alive); 5190 ik->clean_method_data(_is_alive); 5191 5192 // G1 specific cleanup work that has 5193 // been moved here to be done in parallel. 5194 ik->clean_dependent_nmethods(); 5195 } 5196 5197 void work() { 5198 ResourceMark rm; 5199 5200 // One worker will clean the subklass/sibling klass tree. 5201 if (claim_clean_klass_tree_task()) { 5202 Klass::clean_subklass_tree(_is_alive); 5203 } 5204 5205 // All workers will help cleaning the classes, 5206 InstanceKlass* klass; 5207 while ((klass = claim_next_klass()) != NULL) { 5208 clean_klass(klass); 5209 } 5210 } 5211 }; 5212 5213 // To minimize the remark pause times, the tasks below are done in parallel. 5214 class G1ParallelCleaningTask : public AbstractGangTask { 5215 private: 5216 G1StringSymbolTableUnlinkTask _string_symbol_task; 5217 G1CodeCacheUnloadingTask _code_cache_task; 5218 G1KlassCleaningTask _klass_cleaning_task; 5219 5220 public: 5221 // The constructor is run in the VMThread. 5222 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) : 5223 AbstractGangTask("Parallel Cleaning"), 5224 _string_symbol_task(is_alive, process_strings, process_symbols), 5225 _code_cache_task(num_workers, is_alive, unloading_occurred), 5226 _klass_cleaning_task(is_alive) { 5227 } 5228 5229 // The parallel work done by all worker threads. 5230 void work(uint worker_id) { 5231 // Do first pass of code cache cleaning. 5232 _code_cache_task.work_first_pass(worker_id); 5233 5234 // Let the threads mark that the first pass is done. 5235 _code_cache_task.barrier_mark(worker_id); 5236 5237 // Clean the Strings and Symbols. 5238 _string_symbol_task.work(worker_id); 5239 5240 // Wait for all workers to finish the first code cache cleaning pass. 5241 _code_cache_task.barrier_wait(worker_id); 5242 5243 // Do the second code cache cleaning work, which realize on 5244 // the liveness information gathered during the first pass. 5245 _code_cache_task.work_second_pass(worker_id); 5246 5247 // Clean all klasses that were not unloaded. 5248 _klass_cleaning_task.work(); 5249 } 5250 }; 5251 5252 5253 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive, 5254 bool process_strings, 5255 bool process_symbols, 5256 bool class_unloading_occurred) { 5257 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ? 5258 workers()->active_workers() : 1); 5259 5260 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, 5261 n_workers, class_unloading_occurred); 5262 if (G1CollectedHeap::use_parallel_gc_threads()) { 5263 set_par_threads(n_workers); 5264 workers()->run_task(&g1_unlink_task); 5265 set_par_threads(0); 5266 } else { 5267 g1_unlink_task.work(0); 5268 } 5269 } 5270 5271 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive, 5272 bool process_strings, bool process_symbols) { 5273 { 5274 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ? 5275 _g1h->workers()->active_workers() : 1); 5276 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols); 5277 if (G1CollectedHeap::use_parallel_gc_threads()) { 5278 set_par_threads(n_workers); 5279 workers()->run_task(&g1_unlink_task); 5280 set_par_threads(0); 5281 } else { 5282 g1_unlink_task.work(0); 5283 } 5284 } 5285 5286 if (G1StringDedup::is_enabled()) { 5287 G1StringDedup::unlink(is_alive); 5288 } 5289 } 5290 5291 class G1RedirtyLoggedCardsTask : public AbstractGangTask { 5292 private: 5293 DirtyCardQueueSet* _queue; 5294 public: 5295 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { } 5296 5297 virtual void work(uint worker_id) { 5298 double start_time = os::elapsedTime(); 5299 5300 RedirtyLoggedCardTableEntryClosure cl; 5301 if (G1CollectedHeap::heap()->use_parallel_gc_threads()) { 5302 _queue->par_apply_closure_to_all_completed_buffers(&cl); 5303 } else { 5304 _queue->apply_closure_to_all_completed_buffers(&cl); 5305 } 5306 5307 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times(); 5308 timer->record_redirty_logged_cards_time_ms(worker_id, (os::elapsedTime() - start_time) * 1000.0); 5309 timer->record_redirty_logged_cards_processed_cards(worker_id, cl.num_processed()); 5310 } 5311 }; 5312 5313 void G1CollectedHeap::redirty_logged_cards() { 5314 double redirty_logged_cards_start = os::elapsedTime(); 5315 5316 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ? 5317 _g1h->workers()->active_workers() : 1); 5318 5319 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set()); 5320 dirty_card_queue_set().reset_for_par_iteration(); 5321 if (use_parallel_gc_threads()) { 5322 set_par_threads(n_workers); 5323 workers()->run_task(&redirty_task); 5324 set_par_threads(0); 5325 } else { 5326 redirty_task.work(0); 5327 } 5328 5329 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set(); 5330 dcq.merge_bufferlists(&dirty_card_queue_set()); 5331 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed"); 5332 5333 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0); 5334 } 5335 5336 // Weak Reference Processing support 5337 5338 // An always "is_alive" closure that is used to preserve referents. 5339 // If the object is non-null then it's alive. Used in the preservation 5340 // of referent objects that are pointed to by reference objects 5341 // discovered by the CM ref processor. 5342 class G1AlwaysAliveClosure: public BoolObjectClosure { 5343 G1CollectedHeap* _g1; 5344 public: 5345 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 5346 bool do_object_b(oop p) { 5347 if (p != NULL) { 5348 return true; 5349 } 5350 return false; 5351 } 5352 }; 5353 5354 bool G1STWIsAliveClosure::do_object_b(oop p) { 5355 // An object is reachable if it is outside the collection set, 5356 // or is inside and copied. 5357 return !_g1->obj_in_cs(p) || p->is_forwarded(); 5358 } 5359 5360 // Non Copying Keep Alive closure 5361 class G1KeepAliveClosure: public OopClosure { 5362 G1CollectedHeap* _g1; 5363 public: 5364 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 5365 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } 5366 void do_oop(oop* p) { 5367 oop obj = *p; 5368 assert(obj != NULL, "the caller should have filtered out NULL values"); 5369 5370 G1CollectedHeap::in_cset_state_t cset_state = _g1->in_cset_state(obj); 5371 if (cset_state == G1CollectedHeap::InNeither) { 5372 return; 5373 } 5374 if (cset_state == G1CollectedHeap::InCSet) { 5375 assert( obj->is_forwarded(), "invariant" ); 5376 *p = obj->forwardee(); 5377 } else { 5378 assert(!obj->is_forwarded(), "invariant" ); 5379 assert(cset_state == G1CollectedHeap::IsHumongous, 5380 err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state)); 5381 _g1->set_humongous_is_live(obj); 5382 } 5383 } 5384 }; 5385 5386 // Copying Keep Alive closure - can be called from both 5387 // serial and parallel code as long as different worker 5388 // threads utilize different G1ParScanThreadState instances 5389 // and different queues. 5390 5391 class G1CopyingKeepAliveClosure: public OopClosure { 5392 G1CollectedHeap* _g1h; 5393 OopClosure* _copy_non_heap_obj_cl; 5394 G1ParScanThreadState* _par_scan_state; 5395 5396 public: 5397 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, 5398 OopClosure* non_heap_obj_cl, 5399 G1ParScanThreadState* pss): 5400 _g1h(g1h), 5401 _copy_non_heap_obj_cl(non_heap_obj_cl), 5402 _par_scan_state(pss) 5403 {} 5404 5405 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 5406 virtual void do_oop( oop* p) { do_oop_work(p); } 5407 5408 template <class T> void do_oop_work(T* p) { 5409 oop obj = oopDesc::load_decode_heap_oop(p); 5410 5411 if (_g1h->is_in_cset_or_humongous(obj)) { 5412 // If the referent object has been forwarded (either copied 5413 // to a new location or to itself in the event of an 5414 // evacuation failure) then we need to update the reference 5415 // field and, if both reference and referent are in the G1 5416 // heap, update the RSet for the referent. 5417 // 5418 // If the referent has not been forwarded then we have to keep 5419 // it alive by policy. Therefore we have copy the referent. 5420 // 5421 // If the reference field is in the G1 heap then we can push 5422 // on the PSS queue. When the queue is drained (after each 5423 // phase of reference processing) the object and it's followers 5424 // will be copied, the reference field set to point to the 5425 // new location, and the RSet updated. Otherwise we need to 5426 // use the the non-heap or metadata closures directly to copy 5427 // the referent object and update the pointer, while avoiding 5428 // updating the RSet. 5429 5430 if (_g1h->is_in_g1_reserved(p)) { 5431 _par_scan_state->push_on_queue(p); 5432 } else { 5433 assert(!Metaspace::contains((const void*)p), 5434 err_msg("Unexpectedly found a pointer from metadata: " 5435 PTR_FORMAT, p)); 5436 _copy_non_heap_obj_cl->do_oop(p); 5437 } 5438 } 5439 } 5440 }; 5441 5442 // Serial drain queue closure. Called as the 'complete_gc' 5443 // closure for each discovered list in some of the 5444 // reference processing phases. 5445 5446 class G1STWDrainQueueClosure: public VoidClosure { 5447 protected: 5448 G1CollectedHeap* _g1h; 5449 G1ParScanThreadState* _par_scan_state; 5450 5451 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 5452 5453 public: 5454 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : 5455 _g1h(g1h), 5456 _par_scan_state(pss) 5457 { } 5458 5459 void do_void() { 5460 G1ParScanThreadState* const pss = par_scan_state(); 5461 pss->trim_queue(); 5462 } 5463 }; 5464 5465 // Parallel Reference Processing closures 5466 5467 // Implementation of AbstractRefProcTaskExecutor for parallel reference 5468 // processing during G1 evacuation pauses. 5469 5470 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 5471 private: 5472 G1CollectedHeap* _g1h; 5473 RefToScanQueueSet* _queues; 5474 FlexibleWorkGang* _workers; 5475 int _active_workers; 5476 5477 public: 5478 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, 5479 FlexibleWorkGang* workers, 5480 RefToScanQueueSet *task_queues, 5481 int n_workers) : 5482 _g1h(g1h), 5483 _queues(task_queues), 5484 _workers(workers), 5485 _active_workers(n_workers) 5486 { 5487 assert(n_workers > 0, "shouldn't call this otherwise"); 5488 } 5489 5490 // Executes the given task using concurrent marking worker threads. 5491 virtual void execute(ProcessTask& task); 5492 virtual void execute(EnqueueTask& task); 5493 }; 5494 5495 // Gang task for possibly parallel reference processing 5496 5497 class G1STWRefProcTaskProxy: public AbstractGangTask { 5498 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 5499 ProcessTask& _proc_task; 5500 G1CollectedHeap* _g1h; 5501 RefToScanQueueSet *_task_queues; 5502 ParallelTaskTerminator* _terminator; 5503 5504 public: 5505 G1STWRefProcTaskProxy(ProcessTask& proc_task, 5506 G1CollectedHeap* g1h, 5507 RefToScanQueueSet *task_queues, 5508 ParallelTaskTerminator* terminator) : 5509 AbstractGangTask("Process reference objects in parallel"), 5510 _proc_task(proc_task), 5511 _g1h(g1h), 5512 _task_queues(task_queues), 5513 _terminator(terminator) 5514 {} 5515 5516 virtual void work(uint worker_id) { 5517 // The reference processing task executed by a single worker. 5518 ResourceMark rm; 5519 HandleMark hm; 5520 5521 G1STWIsAliveClosure is_alive(_g1h); 5522 5523 G1ParScanThreadState pss(_g1h, worker_id, NULL); 5524 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL); 5525 5526 pss.set_evac_failure_closure(&evac_failure_cl); 5527 5528 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL); 5529 5530 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL); 5531 5532 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5533 5534 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5535 // We also need to mark copied objects. 5536 copy_non_heap_cl = ©_mark_non_heap_cl; 5537 } 5538 5539 // Keep alive closure. 5540 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss); 5541 5542 // Complete GC closure 5543 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator); 5544 5545 // Call the reference processing task's work routine. 5546 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); 5547 5548 // Note we cannot assert that the refs array is empty here as not all 5549 // of the processing tasks (specifically phase2 - pp2_work) execute 5550 // the complete_gc closure (which ordinarily would drain the queue) so 5551 // the queue may not be empty. 5552 } 5553 }; 5554 5555 // Driver routine for parallel reference processing. 5556 // Creates an instance of the ref processing gang 5557 // task and has the worker threads execute it. 5558 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) { 5559 assert(_workers != NULL, "Need parallel worker threads."); 5560 5561 ParallelTaskTerminator terminator(_active_workers, _queues); 5562 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator); 5563 5564 _g1h->set_par_threads(_active_workers); 5565 _workers->run_task(&proc_task_proxy); 5566 _g1h->set_par_threads(0); 5567 } 5568 5569 // Gang task for parallel reference enqueueing. 5570 5571 class G1STWRefEnqueueTaskProxy: public AbstractGangTask { 5572 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; 5573 EnqueueTask& _enq_task; 5574 5575 public: 5576 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) : 5577 AbstractGangTask("Enqueue reference objects in parallel"), 5578 _enq_task(enq_task) 5579 { } 5580 5581 virtual void work(uint worker_id) { 5582 _enq_task.work(worker_id); 5583 } 5584 }; 5585 5586 // Driver routine for parallel reference enqueueing. 5587 // Creates an instance of the ref enqueueing gang 5588 // task and has the worker threads execute it. 5589 5590 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) { 5591 assert(_workers != NULL, "Need parallel worker threads."); 5592 5593 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task); 5594 5595 _g1h->set_par_threads(_active_workers); 5596 _workers->run_task(&enq_task_proxy); 5597 _g1h->set_par_threads(0); 5598 } 5599 5600 // End of weak reference support closures 5601 5602 // Abstract task used to preserve (i.e. copy) any referent objects 5603 // that are in the collection set and are pointed to by reference 5604 // objects discovered by the CM ref processor. 5605 5606 class G1ParPreserveCMReferentsTask: public AbstractGangTask { 5607 protected: 5608 G1CollectedHeap* _g1h; 5609 RefToScanQueueSet *_queues; 5610 ParallelTaskTerminator _terminator; 5611 uint _n_workers; 5612 5613 public: 5614 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) : 5615 AbstractGangTask("ParPreserveCMReferents"), 5616 _g1h(g1h), 5617 _queues(task_queues), 5618 _terminator(workers, _queues), 5619 _n_workers(workers) 5620 { } 5621 5622 void work(uint worker_id) { 5623 ResourceMark rm; 5624 HandleMark hm; 5625 5626 G1ParScanThreadState pss(_g1h, worker_id, NULL); 5627 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL); 5628 5629 pss.set_evac_failure_closure(&evac_failure_cl); 5630 5631 assert(pss.queue_is_empty(), "both queue and overflow should be empty"); 5632 5633 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL); 5634 5635 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL); 5636 5637 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5638 5639 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5640 // We also need to mark copied objects. 5641 copy_non_heap_cl = ©_mark_non_heap_cl; 5642 } 5643 5644 // Is alive closure 5645 G1AlwaysAliveClosure always_alive(_g1h); 5646 5647 // Copying keep alive closure. Applied to referent objects that need 5648 // to be copied. 5649 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss); 5650 5651 ReferenceProcessor* rp = _g1h->ref_processor_cm(); 5652 5653 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q(); 5654 uint stride = MIN2(MAX2(_n_workers, 1U), limit); 5655 5656 // limit is set using max_num_q() - which was set using ParallelGCThreads. 5657 // So this must be true - but assert just in case someone decides to 5658 // change the worker ids. 5659 assert(0 <= worker_id && worker_id < limit, "sanity"); 5660 assert(!rp->discovery_is_atomic(), "check this code"); 5661 5662 // Select discovered lists [i, i+stride, i+2*stride,...,limit) 5663 for (uint idx = worker_id; idx < limit; idx += stride) { 5664 DiscoveredList& ref_list = rp->discovered_refs()[idx]; 5665 5666 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive); 5667 while (iter.has_next()) { 5668 // Since discovery is not atomic for the CM ref processor, we 5669 // can see some null referent objects. 5670 iter.load_ptrs(DEBUG_ONLY(true)); 5671 oop ref = iter.obj(); 5672 5673 // This will filter nulls. 5674 if (iter.is_referent_alive()) { 5675 iter.make_referent_alive(); 5676 } 5677 iter.move_to_next(); 5678 } 5679 } 5680 5681 // Drain the queue - which may cause stealing 5682 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator); 5683 drain_queue.do_void(); 5684 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure 5685 assert(pss.queue_is_empty(), "should be"); 5686 } 5687 }; 5688 5689 // Weak Reference processing during an evacuation pause (part 1). 5690 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) { 5691 double ref_proc_start = os::elapsedTime(); 5692 5693 ReferenceProcessor* rp = _ref_processor_stw; 5694 assert(rp->discovery_enabled(), "should have been enabled"); 5695 5696 // Any reference objects, in the collection set, that were 'discovered' 5697 // by the CM ref processor should have already been copied (either by 5698 // applying the external root copy closure to the discovered lists, or 5699 // by following an RSet entry). 5700 // 5701 // But some of the referents, that are in the collection set, that these 5702 // reference objects point to may not have been copied: the STW ref 5703 // processor would have seen that the reference object had already 5704 // been 'discovered' and would have skipped discovering the reference, 5705 // but would not have treated the reference object as a regular oop. 5706 // As a result the copy closure would not have been applied to the 5707 // referent object. 5708 // 5709 // We need to explicitly copy these referent objects - the references 5710 // will be processed at the end of remarking. 5711 // 5712 // We also need to do this copying before we process the reference 5713 // objects discovered by the STW ref processor in case one of these 5714 // referents points to another object which is also referenced by an 5715 // object discovered by the STW ref processor. 5716 5717 assert(!G1CollectedHeap::use_parallel_gc_threads() || 5718 no_of_gc_workers == workers()->active_workers(), 5719 "Need to reset active GC workers"); 5720 5721 set_par_threads(no_of_gc_workers); 5722 G1ParPreserveCMReferentsTask keep_cm_referents(this, 5723 no_of_gc_workers, 5724 _task_queues); 5725 5726 if (G1CollectedHeap::use_parallel_gc_threads()) { 5727 workers()->run_task(&keep_cm_referents); 5728 } else { 5729 keep_cm_referents.work(0); 5730 } 5731 5732 set_par_threads(0); 5733 5734 // Closure to test whether a referent is alive. 5735 G1STWIsAliveClosure is_alive(this); 5736 5737 // Even when parallel reference processing is enabled, the processing 5738 // of JNI refs is serial and performed serially by the current thread 5739 // rather than by a worker. The following PSS will be used for processing 5740 // JNI refs. 5741 5742 // Use only a single queue for this PSS. 5743 G1ParScanThreadState pss(this, 0, NULL); 5744 5745 // We do not embed a reference processor in the copying/scanning 5746 // closures while we're actually processing the discovered 5747 // reference objects. 5748 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL); 5749 5750 pss.set_evac_failure_closure(&evac_failure_cl); 5751 5752 assert(pss.queue_is_empty(), "pre-condition"); 5753 5754 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL); 5755 5756 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL); 5757 5758 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5759 5760 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5761 // We also need to mark copied objects. 5762 copy_non_heap_cl = ©_mark_non_heap_cl; 5763 } 5764 5765 // Keep alive closure. 5766 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, &pss); 5767 5768 // Serial Complete GC closure 5769 G1STWDrainQueueClosure drain_queue(this, &pss); 5770 5771 // Setup the soft refs policy... 5772 rp->setup_policy(false); 5773 5774 ReferenceProcessorStats stats; 5775 if (!rp->processing_is_mt()) { 5776 // Serial reference processing... 5777 stats = rp->process_discovered_references(&is_alive, 5778 &keep_alive, 5779 &drain_queue, 5780 NULL, 5781 _gc_timer_stw, 5782 _gc_tracer_stw->gc_id()); 5783 } else { 5784 // Parallel reference processing 5785 assert(rp->num_q() == no_of_gc_workers, "sanity"); 5786 assert(no_of_gc_workers <= rp->max_num_q(), "sanity"); 5787 5788 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers); 5789 stats = rp->process_discovered_references(&is_alive, 5790 &keep_alive, 5791 &drain_queue, 5792 &par_task_executor, 5793 _gc_timer_stw, 5794 _gc_tracer_stw->gc_id()); 5795 } 5796 5797 _gc_tracer_stw->report_gc_reference_stats(stats); 5798 5799 // We have completed copying any necessary live referent objects. 5800 assert(pss.queue_is_empty(), "both queue and overflow should be empty"); 5801 5802 double ref_proc_time = os::elapsedTime() - ref_proc_start; 5803 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 5804 } 5805 5806 // Weak Reference processing during an evacuation pause (part 2). 5807 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) { 5808 double ref_enq_start = os::elapsedTime(); 5809 5810 ReferenceProcessor* rp = _ref_processor_stw; 5811 assert(!rp->discovery_enabled(), "should have been disabled as part of processing"); 5812 5813 // Now enqueue any remaining on the discovered lists on to 5814 // the pending list. 5815 if (!rp->processing_is_mt()) { 5816 // Serial reference processing... 5817 rp->enqueue_discovered_references(); 5818 } else { 5819 // Parallel reference enqueueing 5820 5821 assert(no_of_gc_workers == workers()->active_workers(), 5822 "Need to reset active workers"); 5823 assert(rp->num_q() == no_of_gc_workers, "sanity"); 5824 assert(no_of_gc_workers <= rp->max_num_q(), "sanity"); 5825 5826 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers); 5827 rp->enqueue_discovered_references(&par_task_executor); 5828 } 5829 5830 rp->verify_no_references_recorded(); 5831 assert(!rp->discovery_enabled(), "should have been disabled"); 5832 5833 // FIXME 5834 // CM's reference processing also cleans up the string and symbol tables. 5835 // Should we do that here also? We could, but it is a serial operation 5836 // and could significantly increase the pause time. 5837 5838 double ref_enq_time = os::elapsedTime() - ref_enq_start; 5839 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0); 5840 } 5841 5842 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) { 5843 _expand_heap_after_alloc_failure = true; 5844 _evacuation_failed = false; 5845 5846 // Should G1EvacuationFailureALot be in effect for this GC? 5847 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) 5848 5849 g1_rem_set()->prepare_for_oops_into_collection_set_do(); 5850 5851 // Disable the hot card cache. 5852 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 5853 hot_card_cache->reset_hot_cache_claimed_index(); 5854 hot_card_cache->set_use_cache(false); 5855 5856 uint n_workers; 5857 if (G1CollectedHeap::use_parallel_gc_threads()) { 5858 n_workers = 5859 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 5860 workers()->active_workers(), 5861 Threads::number_of_non_daemon_threads()); 5862 assert(UseDynamicNumberOfGCThreads || 5863 n_workers == workers()->total_workers(), 5864 "If not dynamic should be using all the workers"); 5865 workers()->set_active_workers(n_workers); 5866 set_par_threads(n_workers); 5867 } else { 5868 assert(n_par_threads() == 0, 5869 "Should be the original non-parallel value"); 5870 n_workers = 1; 5871 } 5872 5873 G1ParTask g1_par_task(this, _task_queues); 5874 5875 init_for_evac_failure(NULL); 5876 5877 rem_set()->prepare_for_younger_refs_iterate(true); 5878 5879 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty"); 5880 double start_par_time_sec = os::elapsedTime(); 5881 double end_par_time_sec; 5882 5883 { 5884 StrongRootsScope srs(this); 5885 // InitialMark needs claim bits to keep track of the marked-through CLDs. 5886 if (g1_policy()->during_initial_mark_pause()) { 5887 ClassLoaderDataGraph::clear_claimed_marks(); 5888 } 5889 5890 if (G1CollectedHeap::use_parallel_gc_threads()) { 5891 // The individual threads will set their evac-failure closures. 5892 if (PrintTerminationStats) G1ParScanThreadState::print_termination_stats_hdr(); 5893 // These tasks use ShareHeap::_process_strong_tasks 5894 assert(UseDynamicNumberOfGCThreads || 5895 workers()->active_workers() == workers()->total_workers(), 5896 "If not dynamic should be using all the workers"); 5897 workers()->run_task(&g1_par_task); 5898 } else { 5899 g1_par_task.set_for_termination(n_workers); 5900 g1_par_task.work(0); 5901 } 5902 end_par_time_sec = os::elapsedTime(); 5903 5904 // Closing the inner scope will execute the destructor 5905 // for the StrongRootsScope object. We record the current 5906 // elapsed time before closing the scope so that time 5907 // taken for the SRS destructor is NOT included in the 5908 // reported parallel time. 5909 } 5910 5911 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0; 5912 g1_policy()->phase_times()->record_par_time(par_time_ms); 5913 5914 double code_root_fixup_time_ms = 5915 (os::elapsedTime() - end_par_time_sec) * 1000.0; 5916 g1_policy()->phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms); 5917 5918 set_par_threads(0); 5919 5920 // Process any discovered reference objects - we have 5921 // to do this _before_ we retire the GC alloc regions 5922 // as we may have to copy some 'reachable' referent 5923 // objects (and their reachable sub-graphs) that were 5924 // not copied during the pause. 5925 process_discovered_references(n_workers); 5926 5927 // Weak root processing. 5928 { 5929 G1STWIsAliveClosure is_alive(this); 5930 G1KeepAliveClosure keep_alive(this); 5931 JNIHandles::weak_oops_do(&is_alive, &keep_alive); 5932 if (G1StringDedup::is_enabled()) { 5933 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive); 5934 } 5935 } 5936 5937 _allocator->release_gc_alloc_regions(n_workers, evacuation_info); 5938 g1_rem_set()->cleanup_after_oops_into_collection_set_do(); 5939 5940 // Reset and re-enable the hot card cache. 5941 // Note the counts for the cards in the regions in the 5942 // collection set are reset when the collection set is freed. 5943 hot_card_cache->reset_hot_cache(); 5944 hot_card_cache->set_use_cache(true); 5945 5946 purge_code_root_memory(); 5947 5948 if (g1_policy()->during_initial_mark_pause()) { 5949 // Reset the claim values set during marking the strong code roots 5950 reset_heap_region_claim_values(); 5951 } 5952 5953 finalize_for_evac_failure(); 5954 5955 if (evacuation_failed()) { 5956 remove_self_forwarding_pointers(); 5957 5958 // Reset the G1EvacuationFailureALot counters and flags 5959 // Note: the values are reset only when an actual 5960 // evacuation failure occurs. 5961 NOT_PRODUCT(reset_evacuation_should_fail();) 5962 } 5963 5964 // Enqueue any remaining references remaining on the STW 5965 // reference processor's discovered lists. We need to do 5966 // this after the card table is cleaned (and verified) as 5967 // the act of enqueueing entries on to the pending list 5968 // will log these updates (and dirty their associated 5969 // cards). We need these updates logged to update any 5970 // RSets. 5971 enqueue_discovered_references(n_workers); 5972 5973 redirty_logged_cards(); 5974 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 5975 } 5976 5977 void G1CollectedHeap::free_region(HeapRegion* hr, 5978 FreeRegionList* free_list, 5979 bool par, 5980 bool locked) { 5981 assert(!hr->is_free(), "the region should not be free"); 5982 assert(!hr->is_empty(), "the region should not be empty"); 5983 assert(_hrm.is_available(hr->hrm_index()), "region should be committed"); 5984 assert(free_list != NULL, "pre-condition"); 5985 5986 if (G1VerifyBitmaps) { 5987 MemRegion mr(hr->bottom(), hr->end()); 5988 concurrent_mark()->clearRangePrevBitmap(mr); 5989 } 5990 5991 // Clear the card counts for this region. 5992 // Note: we only need to do this if the region is not young 5993 // (since we don't refine cards in young regions). 5994 if (!hr->is_young()) { 5995 _cg1r->hot_card_cache()->reset_card_counts(hr); 5996 } 5997 hr->hr_clear(par, true /* clear_space */, locked /* locked */); 5998 free_list->add_ordered(hr); 5999 } 6000 6001 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 6002 FreeRegionList* free_list, 6003 bool par) { 6004 assert(hr->is_starts_humongous(), "this is only for starts humongous regions"); 6005 assert(free_list != NULL, "pre-condition"); 6006 6007 size_t hr_capacity = hr->capacity(); 6008 // We need to read this before we make the region non-humongous, 6009 // otherwise the information will be gone. 6010 uint last_index = hr->last_hc_index(); 6011 hr->clear_humongous(); 6012 free_region(hr, free_list, par); 6013 6014 uint i = hr->hrm_index() + 1; 6015 while (i < last_index) { 6016 HeapRegion* curr_hr = region_at(i); 6017 assert(curr_hr->is_continues_humongous(), "invariant"); 6018 curr_hr->clear_humongous(); 6019 free_region(curr_hr, free_list, par); 6020 i += 1; 6021 } 6022 } 6023 6024 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed, 6025 const HeapRegionSetCount& humongous_regions_removed) { 6026 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) { 6027 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 6028 _old_set.bulk_remove(old_regions_removed); 6029 _humongous_set.bulk_remove(humongous_regions_removed); 6030 } 6031 6032 } 6033 6034 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) { 6035 assert(list != NULL, "list can't be null"); 6036 if (!list->is_empty()) { 6037 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag); 6038 _hrm.insert_list_into_free_list(list); 6039 } 6040 } 6041 6042 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) { 6043 _allocator->decrease_used(bytes); 6044 } 6045 6046 class G1ParCleanupCTTask : public AbstractGangTask { 6047 G1SATBCardTableModRefBS* _ct_bs; 6048 G1CollectedHeap* _g1h; 6049 HeapRegion* volatile _su_head; 6050 public: 6051 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs, 6052 G1CollectedHeap* g1h) : 6053 AbstractGangTask("G1 Par Cleanup CT Task"), 6054 _ct_bs(ct_bs), _g1h(g1h) { } 6055 6056 void work(uint worker_id) { 6057 HeapRegion* r; 6058 while (r = _g1h->pop_dirty_cards_region()) { 6059 clear_cards(r); 6060 } 6061 } 6062 6063 void clear_cards(HeapRegion* r) { 6064 // Cards of the survivors should have already been dirtied. 6065 if (!r->is_survivor()) { 6066 _ct_bs->clear(MemRegion(r->bottom(), r->end())); 6067 } 6068 } 6069 }; 6070 6071 #ifndef PRODUCT 6072 class G1VerifyCardTableCleanup: public HeapRegionClosure { 6073 G1CollectedHeap* _g1h; 6074 G1SATBCardTableModRefBS* _ct_bs; 6075 public: 6076 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs) 6077 : _g1h(g1h), _ct_bs(ct_bs) { } 6078 virtual bool doHeapRegion(HeapRegion* r) { 6079 if (r->is_survivor()) { 6080 _g1h->verify_dirty_region(r); 6081 } else { 6082 _g1h->verify_not_dirty_region(r); 6083 } 6084 return false; 6085 } 6086 }; 6087 6088 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) { 6089 // All of the region should be clean. 6090 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 6091 MemRegion mr(hr->bottom(), hr->end()); 6092 ct_bs->verify_not_dirty_region(mr); 6093 } 6094 6095 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) { 6096 // We cannot guarantee that [bottom(),end()] is dirty. Threads 6097 // dirty allocated blocks as they allocate them. The thread that 6098 // retires each region and replaces it with a new one will do a 6099 // maximal allocation to fill in [pre_dummy_top(),end()] but will 6100 // not dirty that area (one less thing to have to do while holding 6101 // a lock). So we can only verify that [bottom(),pre_dummy_top()] 6102 // is dirty. 6103 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 6104 MemRegion mr(hr->bottom(), hr->pre_dummy_top()); 6105 if (hr->is_young()) { 6106 ct_bs->verify_g1_young_region(mr); 6107 } else { 6108 ct_bs->verify_dirty_region(mr); 6109 } 6110 } 6111 6112 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) { 6113 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 6114 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) { 6115 verify_dirty_region(hr); 6116 } 6117 } 6118 6119 void G1CollectedHeap::verify_dirty_young_regions() { 6120 verify_dirty_young_list(_young_list->first_region()); 6121 } 6122 6123 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap, 6124 HeapWord* tams, HeapWord* end) { 6125 guarantee(tams <= end, 6126 err_msg("tams: "PTR_FORMAT" end: "PTR_FORMAT, tams, end)); 6127 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end); 6128 if (result < end) { 6129 gclog_or_tty->cr(); 6130 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: "PTR_FORMAT, 6131 bitmap_name, result); 6132 gclog_or_tty->print_cr("## %s tams: "PTR_FORMAT" end: "PTR_FORMAT, 6133 bitmap_name, tams, end); 6134 return false; 6135 } 6136 return true; 6137 } 6138 6139 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) { 6140 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap(); 6141 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap(); 6142 6143 HeapWord* bottom = hr->bottom(); 6144 HeapWord* ptams = hr->prev_top_at_mark_start(); 6145 HeapWord* ntams = hr->next_top_at_mark_start(); 6146 HeapWord* end = hr->end(); 6147 6148 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end); 6149 6150 bool res_n = true; 6151 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window 6152 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap 6153 // if we happen to be in that state. 6154 if (mark_in_progress() || !_cmThread->in_progress()) { 6155 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end); 6156 } 6157 if (!res_p || !res_n) { 6158 gclog_or_tty->print_cr("#### Bitmap verification failed for "HR_FORMAT, 6159 HR_FORMAT_PARAMS(hr)); 6160 gclog_or_tty->print_cr("#### Caller: %s", caller); 6161 return false; 6162 } 6163 return true; 6164 } 6165 6166 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) { 6167 if (!G1VerifyBitmaps) return; 6168 6169 guarantee(verify_bitmaps(caller, hr), "bitmap verification"); 6170 } 6171 6172 class G1VerifyBitmapClosure : public HeapRegionClosure { 6173 private: 6174 const char* _caller; 6175 G1CollectedHeap* _g1h; 6176 bool _failures; 6177 6178 public: 6179 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) : 6180 _caller(caller), _g1h(g1h), _failures(false) { } 6181 6182 bool failures() { return _failures; } 6183 6184 virtual bool doHeapRegion(HeapRegion* hr) { 6185 if (hr->is_continues_humongous()) return false; 6186 6187 bool result = _g1h->verify_bitmaps(_caller, hr); 6188 if (!result) { 6189 _failures = true; 6190 } 6191 return false; 6192 } 6193 }; 6194 6195 void G1CollectedHeap::check_bitmaps(const char* caller) { 6196 if (!G1VerifyBitmaps) return; 6197 6198 G1VerifyBitmapClosure cl(caller, this); 6199 heap_region_iterate(&cl); 6200 guarantee(!cl.failures(), "bitmap verification"); 6201 } 6202 #endif // PRODUCT 6203 6204 void G1CollectedHeap::cleanUpCardTable() { 6205 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 6206 double start = os::elapsedTime(); 6207 6208 { 6209 // Iterate over the dirty cards region list. 6210 G1ParCleanupCTTask cleanup_task(ct_bs, this); 6211 6212 if (G1CollectedHeap::use_parallel_gc_threads()) { 6213 set_par_threads(); 6214 workers()->run_task(&cleanup_task); 6215 set_par_threads(0); 6216 } else { 6217 while (_dirty_cards_region_list) { 6218 HeapRegion* r = _dirty_cards_region_list; 6219 cleanup_task.clear_cards(r); 6220 _dirty_cards_region_list = r->get_next_dirty_cards_region(); 6221 if (_dirty_cards_region_list == r) { 6222 // The last region. 6223 _dirty_cards_region_list = NULL; 6224 } 6225 r->set_next_dirty_cards_region(NULL); 6226 } 6227 } 6228 #ifndef PRODUCT 6229 if (G1VerifyCTCleanup || VerifyAfterGC) { 6230 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs); 6231 heap_region_iterate(&cleanup_verifier); 6232 } 6233 #endif 6234 } 6235 6236 double elapsed = os::elapsedTime() - start; 6237 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0); 6238 } 6239 6240 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) { 6241 size_t pre_used = 0; 6242 FreeRegionList local_free_list("Local List for CSet Freeing"); 6243 6244 double young_time_ms = 0.0; 6245 double non_young_time_ms = 0.0; 6246 6247 // Since the collection set is a superset of the the young list, 6248 // all we need to do to clear the young list is clear its 6249 // head and length, and unlink any young regions in the code below 6250 _young_list->clear(); 6251 6252 G1CollectorPolicy* policy = g1_policy(); 6253 6254 double start_sec = os::elapsedTime(); 6255 bool non_young = true; 6256 6257 HeapRegion* cur = cs_head; 6258 int age_bound = -1; 6259 size_t rs_lengths = 0; 6260 6261 while (cur != NULL) { 6262 assert(!is_on_master_free_list(cur), "sanity"); 6263 if (non_young) { 6264 if (cur->is_young()) { 6265 double end_sec = os::elapsedTime(); 6266 double elapsed_ms = (end_sec - start_sec) * 1000.0; 6267 non_young_time_ms += elapsed_ms; 6268 6269 start_sec = os::elapsedTime(); 6270 non_young = false; 6271 } 6272 } else { 6273 if (!cur->is_young()) { 6274 double end_sec = os::elapsedTime(); 6275 double elapsed_ms = (end_sec - start_sec) * 1000.0; 6276 young_time_ms += elapsed_ms; 6277 6278 start_sec = os::elapsedTime(); 6279 non_young = true; 6280 } 6281 } 6282 6283 rs_lengths += cur->rem_set()->occupied_locked(); 6284 6285 HeapRegion* next = cur->next_in_collection_set(); 6286 assert(cur->in_collection_set(), "bad CS"); 6287 cur->set_next_in_collection_set(NULL); 6288 cur->set_in_collection_set(false); 6289 6290 if (cur->is_young()) { 6291 int index = cur->young_index_in_cset(); 6292 assert(index != -1, "invariant"); 6293 assert((uint) index < policy->young_cset_region_length(), "invariant"); 6294 size_t words_survived = _surviving_young_words[index]; 6295 cur->record_surv_words_in_group(words_survived); 6296 6297 // At this point the we have 'popped' cur from the collection set 6298 // (linked via next_in_collection_set()) but it is still in the 6299 // young list (linked via next_young_region()). Clear the 6300 // _next_young_region field. 6301 cur->set_next_young_region(NULL); 6302 } else { 6303 int index = cur->young_index_in_cset(); 6304 assert(index == -1, "invariant"); 6305 } 6306 6307 assert( (cur->is_young() && cur->young_index_in_cset() > -1) || 6308 (!cur->is_young() && cur->young_index_in_cset() == -1), 6309 "invariant" ); 6310 6311 if (!cur->evacuation_failed()) { 6312 MemRegion used_mr = cur->used_region(); 6313 6314 // And the region is empty. 6315 assert(!used_mr.is_empty(), "Should not have empty regions in a CS."); 6316 pre_used += cur->used(); 6317 free_region(cur, &local_free_list, false /* par */, true /* locked */); 6318 } else { 6319 cur->uninstall_surv_rate_group(); 6320 if (cur->is_young()) { 6321 cur->set_young_index_in_cset(-1); 6322 } 6323 cur->set_evacuation_failed(false); 6324 // The region is now considered to be old. 6325 cur->set_old(); 6326 _old_set.add(cur); 6327 evacuation_info.increment_collectionset_used_after(cur->used()); 6328 } 6329 cur = next; 6330 } 6331 6332 evacuation_info.set_regions_freed(local_free_list.length()); 6333 policy->record_max_rs_lengths(rs_lengths); 6334 policy->cset_regions_freed(); 6335 6336 double end_sec = os::elapsedTime(); 6337 double elapsed_ms = (end_sec - start_sec) * 1000.0; 6338 6339 if (non_young) { 6340 non_young_time_ms += elapsed_ms; 6341 } else { 6342 young_time_ms += elapsed_ms; 6343 } 6344 6345 prepend_to_freelist(&local_free_list); 6346 decrement_summary_bytes(pre_used); 6347 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms); 6348 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms); 6349 } 6350 6351 class G1FreeHumongousRegionClosure : public HeapRegionClosure { 6352 private: 6353 FreeRegionList* _free_region_list; 6354 HeapRegionSet* _proxy_set; 6355 HeapRegionSetCount _humongous_regions_removed; 6356 size_t _freed_bytes; 6357 public: 6358 6359 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) : 6360 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) { 6361 } 6362 6363 virtual bool doHeapRegion(HeapRegion* r) { 6364 if (!r->is_starts_humongous()) { 6365 return false; 6366 } 6367 6368 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 6369 6370 oop obj = (oop)r->bottom(); 6371 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap(); 6372 6373 // The following checks whether the humongous object is live are sufficient. 6374 // The main additional check (in addition to having a reference from the roots 6375 // or the young gen) is whether the humongous object has a remembered set entry. 6376 // 6377 // A humongous object cannot be live if there is no remembered set for it 6378 // because: 6379 // - there can be no references from within humongous starts regions referencing 6380 // the object because we never allocate other objects into them. 6381 // (I.e. there are no intra-region references that may be missed by the 6382 // remembered set) 6383 // - as soon there is a remembered set entry to the humongous starts region 6384 // (i.e. it has "escaped" to an old object) this remembered set entry will stay 6385 // until the end of a concurrent mark. 6386 // 6387 // It is not required to check whether the object has been found dead by marking 6388 // or not, in fact it would prevent reclamation within a concurrent cycle, as 6389 // all objects allocated during that time are considered live. 6390 // SATB marking is even more conservative than the remembered set. 6391 // So if at this point in the collection there is no remembered set entry, 6392 // nobody has a reference to it. 6393 // At the start of collection we flush all refinement logs, and remembered sets 6394 // are completely up-to-date wrt to references to the humongous object. 6395 // 6396 // Other implementation considerations: 6397 // - never consider object arrays: while they are a valid target, they have not 6398 // been observed to be used as temporary objects. 6399 // - they would also pose considerable effort for cleaning up the the remembered 6400 // sets. 6401 // While this cleanup is not strictly necessary to be done (or done instantly), 6402 // given that their occurrence is very low, this saves us this additional 6403 // complexity. 6404 uint region_idx = r->hrm_index(); 6405 if (g1h->humongous_is_live(region_idx) || 6406 g1h->humongous_region_is_always_live(region_idx)) { 6407 6408 if (G1TraceReclaimDeadHumongousObjectsAtYoungGC) { 6409 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", 6410 r->is_humongous(), 6411 region_idx, 6412 r->rem_set()->occupied(), 6413 r->rem_set()->strong_code_roots_list_length(), 6414 next_bitmap->isMarked(r->bottom()), 6415 g1h->humongous_is_live(region_idx), 6416 obj->is_objArray() 6417 ); 6418 } 6419 6420 return false; 6421 } 6422 6423 guarantee(!obj->is_objArray(), 6424 err_msg("Eagerly reclaiming object arrays is not supported, but the object "PTR_FORMAT" is.", 6425 r->bottom())); 6426 6427 if (G1TraceReclaimDeadHumongousObjectsAtYoungGC) { 6428 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", 6429 r->is_humongous(), 6430 r->bottom(), 6431 region_idx, 6432 r->region_num(), 6433 r->rem_set()->occupied(), 6434 r->rem_set()->strong_code_roots_list_length(), 6435 next_bitmap->isMarked(r->bottom()), 6436 g1h->humongous_is_live(region_idx), 6437 obj->is_objArray() 6438 ); 6439 } 6440 // Need to clear mark bit of the humongous object if already set. 6441 if (next_bitmap->isMarked(r->bottom())) { 6442 next_bitmap->clear(r->bottom()); 6443 } 6444 _freed_bytes += r->used(); 6445 r->set_containing_set(NULL); 6446 _humongous_regions_removed.increment(1u, r->capacity()); 6447 g1h->free_humongous_region(r, _free_region_list, false); 6448 6449 return false; 6450 } 6451 6452 HeapRegionSetCount& humongous_free_count() { 6453 return _humongous_regions_removed; 6454 } 6455 6456 size_t bytes_freed() const { 6457 return _freed_bytes; 6458 } 6459 6460 size_t humongous_reclaimed() const { 6461 return _humongous_regions_removed.length(); 6462 } 6463 }; 6464 6465 void G1CollectedHeap::eagerly_reclaim_humongous_regions() { 6466 assert_at_safepoint(true); 6467 6468 if (!G1ReclaimDeadHumongousObjectsAtYoungGC || !_has_humongous_reclaim_candidates) { 6469 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0); 6470 return; 6471 } 6472 6473 double start_time = os::elapsedTime(); 6474 6475 FreeRegionList local_cleanup_list("Local Humongous Cleanup List"); 6476 6477 G1FreeHumongousRegionClosure cl(&local_cleanup_list); 6478 heap_region_iterate(&cl); 6479 6480 HeapRegionSetCount empty_set; 6481 remove_from_old_sets(empty_set, cl.humongous_free_count()); 6482 6483 G1HRPrinter* hr_printer = _g1h->hr_printer(); 6484 if (hr_printer->is_active()) { 6485 FreeRegionListIterator iter(&local_cleanup_list); 6486 while (iter.more_available()) { 6487 HeapRegion* hr = iter.get_next(); 6488 hr_printer->cleanup(hr); 6489 } 6490 } 6491 6492 prepend_to_freelist(&local_cleanup_list); 6493 decrement_summary_bytes(cl.bytes_freed()); 6494 6495 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0, 6496 cl.humongous_reclaimed()); 6497 } 6498 6499 // This routine is similar to the above but does not record 6500 // any policy statistics or update free lists; we are abandoning 6501 // the current incremental collection set in preparation of a 6502 // full collection. After the full GC we will start to build up 6503 // the incremental collection set again. 6504 // This is only called when we're doing a full collection 6505 // and is immediately followed by the tearing down of the young list. 6506 6507 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) { 6508 HeapRegion* cur = cs_head; 6509 6510 while (cur != NULL) { 6511 HeapRegion* next = cur->next_in_collection_set(); 6512 assert(cur->in_collection_set(), "bad CS"); 6513 cur->set_next_in_collection_set(NULL); 6514 cur->set_in_collection_set(false); 6515 cur->set_young_index_in_cset(-1); 6516 cur = next; 6517 } 6518 } 6519 6520 void G1CollectedHeap::set_free_regions_coming() { 6521 if (G1ConcRegionFreeingVerbose) { 6522 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " 6523 "setting free regions coming"); 6524 } 6525 6526 assert(!free_regions_coming(), "pre-condition"); 6527 _free_regions_coming = true; 6528 } 6529 6530 void G1CollectedHeap::reset_free_regions_coming() { 6531 assert(free_regions_coming(), "pre-condition"); 6532 6533 { 6534 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6535 _free_regions_coming = false; 6536 SecondaryFreeList_lock->notify_all(); 6537 } 6538 6539 if (G1ConcRegionFreeingVerbose) { 6540 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " 6541 "reset free regions coming"); 6542 } 6543 } 6544 6545 void G1CollectedHeap::wait_while_free_regions_coming() { 6546 // Most of the time we won't have to wait, so let's do a quick test 6547 // first before we take the lock. 6548 if (!free_regions_coming()) { 6549 return; 6550 } 6551 6552 if (G1ConcRegionFreeingVerbose) { 6553 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " 6554 "waiting for free regions"); 6555 } 6556 6557 { 6558 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6559 while (free_regions_coming()) { 6560 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 6561 } 6562 } 6563 6564 if (G1ConcRegionFreeingVerbose) { 6565 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " 6566 "done waiting for free regions"); 6567 } 6568 } 6569 6570 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 6571 assert(heap_lock_held_for_gc(), 6572 "the heap lock should already be held by or for this thread"); 6573 _young_list->push_region(hr); 6574 } 6575 6576 class NoYoungRegionsClosure: public HeapRegionClosure { 6577 private: 6578 bool _success; 6579 public: 6580 NoYoungRegionsClosure() : _success(true) { } 6581 bool doHeapRegion(HeapRegion* r) { 6582 if (r->is_young()) { 6583 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young", 6584 r->bottom(), r->end()); 6585 _success = false; 6586 } 6587 return false; 6588 } 6589 bool success() { return _success; } 6590 }; 6591 6592 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) { 6593 bool ret = _young_list->check_list_empty(check_sample); 6594 6595 if (check_heap) { 6596 NoYoungRegionsClosure closure; 6597 heap_region_iterate(&closure); 6598 ret = ret && closure.success(); 6599 } 6600 6601 return ret; 6602 } 6603 6604 class TearDownRegionSetsClosure : public HeapRegionClosure { 6605 private: 6606 HeapRegionSet *_old_set; 6607 6608 public: 6609 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { } 6610 6611 bool doHeapRegion(HeapRegion* r) { 6612 if (r->is_old()) { 6613 _old_set->remove(r); 6614 } else { 6615 // We ignore free regions, we'll empty the free list afterwards. 6616 // We ignore young regions, we'll empty the young list afterwards. 6617 // We ignore humongous regions, we're not tearing down the 6618 // humongous regions set. 6619 assert(r->is_free() || r->is_young() || r->is_humongous(), 6620 "it cannot be another type"); 6621 } 6622 return false; 6623 } 6624 6625 ~TearDownRegionSetsClosure() { 6626 assert(_old_set->is_empty(), "post-condition"); 6627 } 6628 }; 6629 6630 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) { 6631 assert_at_safepoint(true /* should_be_vm_thread */); 6632 6633 if (!free_list_only) { 6634 TearDownRegionSetsClosure cl(&_old_set); 6635 heap_region_iterate(&cl); 6636 6637 // Note that emptying the _young_list is postponed and instead done as 6638 // the first step when rebuilding the regions sets again. The reason for 6639 // this is that during a full GC string deduplication needs to know if 6640 // a collected region was young or old when the full GC was initiated. 6641 } 6642 _hrm.remove_all_free_regions(); 6643 } 6644 6645 class RebuildRegionSetsClosure : public HeapRegionClosure { 6646 private: 6647 bool _free_list_only; 6648 HeapRegionSet* _old_set; 6649 HeapRegionManager* _hrm; 6650 size_t _total_used; 6651 6652 public: 6653 RebuildRegionSetsClosure(bool free_list_only, 6654 HeapRegionSet* old_set, HeapRegionManager* hrm) : 6655 _free_list_only(free_list_only), 6656 _old_set(old_set), _hrm(hrm), _total_used(0) { 6657 assert(_hrm->num_free_regions() == 0, "pre-condition"); 6658 if (!free_list_only) { 6659 assert(_old_set->is_empty(), "pre-condition"); 6660 } 6661 } 6662 6663 bool doHeapRegion(HeapRegion* r) { 6664 if (r->is_continues_humongous()) { 6665 return false; 6666 } 6667 6668 if (r->is_empty()) { 6669 // Add free regions to the free list 6670 r->set_free(); 6671 r->set_allocation_context(AllocationContext::system()); 6672 _hrm->insert_into_free_list(r); 6673 } else if (!_free_list_only) { 6674 assert(!r->is_young(), "we should not come across young regions"); 6675 6676 if (r->is_humongous()) { 6677 // We ignore humongous regions, we left the humongous set unchanged 6678 } else { 6679 // Objects that were compacted would have ended up on regions 6680 // that were previously old or free. 6681 assert(r->is_free() || r->is_old(), "invariant"); 6682 // We now consider them old, so register as such. 6683 r->set_old(); 6684 _old_set->add(r); 6685 } 6686 _total_used += r->used(); 6687 } 6688 6689 return false; 6690 } 6691 6692 size_t total_used() { 6693 return _total_used; 6694 } 6695 }; 6696 6697 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { 6698 assert_at_safepoint(true /* should_be_vm_thread */); 6699 6700 if (!free_list_only) { 6701 _young_list->empty_list(); 6702 } 6703 6704 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm); 6705 heap_region_iterate(&cl); 6706 6707 if (!free_list_only) { 6708 _allocator->set_used(cl.total_used()); 6709 } 6710 assert(_allocator->used_unlocked() == recalculate_used(), 6711 err_msg("inconsistent _allocator->used_unlocked(), " 6712 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT, 6713 _allocator->used_unlocked(), recalculate_used())); 6714 } 6715 6716 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) { 6717 _refine_cte_cl->set_concurrent(concurrent); 6718 } 6719 6720 bool G1CollectedHeap::is_in_closed_subset(const void* p) const { 6721 HeapRegion* hr = heap_region_containing(p); 6722 return hr->is_in(p); 6723 } 6724 6725 // Methods for the mutator alloc region 6726 6727 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 6728 bool force) { 6729 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6730 assert(!force || g1_policy()->can_expand_young_list(), 6731 "if force is true we should be able to expand the young list"); 6732 bool young_list_full = g1_policy()->is_young_list_full(); 6733 if (force || !young_list_full) { 6734 HeapRegion* new_alloc_region = new_region(word_size, 6735 false /* is_old */, 6736 false /* do_expand */); 6737 if (new_alloc_region != NULL) { 6738 set_region_short_lived_locked(new_alloc_region); 6739 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full); 6740 check_bitmaps("Mutator Region Allocation", new_alloc_region); 6741 return new_alloc_region; 6742 } 6743 } 6744 return NULL; 6745 } 6746 6747 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 6748 size_t allocated_bytes) { 6749 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6750 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden"); 6751 6752 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region); 6753 _allocator->increase_used(allocated_bytes); 6754 _hr_printer.retire(alloc_region); 6755 // We update the eden sizes here, when the region is retired, 6756 // instead of when it's allocated, since this is the point that its 6757 // used space has been recored in _summary_bytes_used. 6758 g1mm()->update_eden_size(); 6759 } 6760 6761 void G1CollectedHeap::set_par_threads() { 6762 // Don't change the number of workers. Use the value previously set 6763 // in the workgroup. 6764 assert(G1CollectedHeap::use_parallel_gc_threads(), "shouldn't be here otherwise"); 6765 uint n_workers = workers()->active_workers(); 6766 assert(UseDynamicNumberOfGCThreads || 6767 n_workers == workers()->total_workers(), 6768 "Otherwise should be using the total number of workers"); 6769 if (n_workers == 0) { 6770 assert(false, "Should have been set in prior evacuation pause."); 6771 n_workers = ParallelGCThreads; 6772 workers()->set_active_workers(n_workers); 6773 } 6774 set_par_threads(n_workers); 6775 } 6776 6777 // Methods for the GC alloc regions 6778 6779 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, 6780 uint count, 6781 GCAllocPurpose ap) { 6782 assert(FreeList_lock->owned_by_self(), "pre-condition"); 6783 6784 if (count < g1_policy()->max_regions(ap)) { 6785 bool survivor = (ap == GCAllocForSurvived); 6786 HeapRegion* new_alloc_region = new_region(word_size, 6787 !survivor, 6788 true /* do_expand */); 6789 if (new_alloc_region != NULL) { 6790 // We really only need to do this for old regions given that we 6791 // should never scan survivors. But it doesn't hurt to do it 6792 // for survivors too. 6793 new_alloc_region->record_top_and_timestamp(); 6794 if (survivor) { 6795 new_alloc_region->set_survivor(); 6796 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor); 6797 check_bitmaps("Survivor Region Allocation", new_alloc_region); 6798 } else { 6799 new_alloc_region->set_old(); 6800 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old); 6801 check_bitmaps("Old Region Allocation", new_alloc_region); 6802 } 6803 bool during_im = g1_policy()->during_initial_mark_pause(); 6804 new_alloc_region->note_start_of_copying(during_im); 6805 return new_alloc_region; 6806 } else { 6807 g1_policy()->note_alloc_region_limit_reached(ap); 6808 } 6809 } 6810 return NULL; 6811 } 6812 6813 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 6814 size_t allocated_bytes, 6815 GCAllocPurpose ap) { 6816 bool during_im = g1_policy()->during_initial_mark_pause(); 6817 alloc_region->note_end_of_copying(during_im); 6818 g1_policy()->record_bytes_copied_during_gc(allocated_bytes); 6819 if (ap == GCAllocForSurvived) { 6820 young_list()->add_survivor_region(alloc_region); 6821 } else { 6822 _old_set.add(alloc_region); 6823 } 6824 _hr_printer.retire(alloc_region); 6825 } 6826 6827 // Heap region set verification 6828 6829 class VerifyRegionListsClosure : public HeapRegionClosure { 6830 private: 6831 HeapRegionSet* _old_set; 6832 HeapRegionSet* _humongous_set; 6833 HeapRegionManager* _hrm; 6834 6835 public: 6836 HeapRegionSetCount _old_count; 6837 HeapRegionSetCount _humongous_count; 6838 HeapRegionSetCount _free_count; 6839 6840 VerifyRegionListsClosure(HeapRegionSet* old_set, 6841 HeapRegionSet* humongous_set, 6842 HeapRegionManager* hrm) : 6843 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm), 6844 _old_count(), _humongous_count(), _free_count(){ } 6845 6846 bool doHeapRegion(HeapRegion* hr) { 6847 if (hr->is_continues_humongous()) { 6848 return false; 6849 } 6850 6851 if (hr->is_young()) { 6852 // TODO 6853 } else if (hr->is_starts_humongous()) { 6854 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrm_index())); 6855 _humongous_count.increment(1u, hr->capacity()); 6856 } else if (hr->is_empty()) { 6857 assert(_hrm->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrm_index())); 6858 _free_count.increment(1u, hr->capacity()); 6859 } else if (hr->is_old()) { 6860 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrm_index())); 6861 _old_count.increment(1u, hr->capacity()); 6862 } else { 6863 ShouldNotReachHere(); 6864 } 6865 return false; 6866 } 6867 6868 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) { 6869 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length())); 6870 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6871 old_set->total_capacity_bytes(), _old_count.capacity())); 6872 6873 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length())); 6874 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6875 humongous_set->total_capacity_bytes(), _humongous_count.capacity())); 6876 6877 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())); 6878 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6879 free_list->total_capacity_bytes(), _free_count.capacity())); 6880 } 6881 }; 6882 6883 void G1CollectedHeap::verify_region_sets() { 6884 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6885 6886 // First, check the explicit lists. 6887 _hrm.verify(); 6888 { 6889 // Given that a concurrent operation might be adding regions to 6890 // the secondary free list we have to take the lock before 6891 // verifying it. 6892 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6893 _secondary_free_list.verify_list(); 6894 } 6895 6896 // If a concurrent region freeing operation is in progress it will 6897 // be difficult to correctly attributed any free regions we come 6898 // across to the correct free list given that they might belong to 6899 // one of several (free_list, secondary_free_list, any local lists, 6900 // etc.). So, if that's the case we will skip the rest of the 6901 // verification operation. Alternatively, waiting for the concurrent 6902 // operation to complete will have a non-trivial effect on the GC's 6903 // operation (no concurrent operation will last longer than the 6904 // interval between two calls to verification) and it might hide 6905 // any issues that we would like to catch during testing. 6906 if (free_regions_coming()) { 6907 return; 6908 } 6909 6910 // Make sure we append the secondary_free_list on the free_list so 6911 // that all free regions we will come across can be safely 6912 // attributed to the free_list. 6913 append_secondary_free_list_if_not_empty_with_lock(); 6914 6915 // Finally, make sure that the region accounting in the lists is 6916 // consistent with what we see in the heap. 6917 6918 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm); 6919 heap_region_iterate(&cl); 6920 cl.verify_counts(&_old_set, &_humongous_set, &_hrm); 6921 } 6922 6923 // Optimized nmethod scanning 6924 6925 class RegisterNMethodOopClosure: public OopClosure { 6926 G1CollectedHeap* _g1h; 6927 nmethod* _nm; 6928 6929 template <class T> void do_oop_work(T* p) { 6930 T heap_oop = oopDesc::load_heap_oop(p); 6931 if (!oopDesc::is_null(heap_oop)) { 6932 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 6933 HeapRegion* hr = _g1h->heap_region_containing(obj); 6934 assert(!hr->is_continues_humongous(), 6935 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT 6936 " starting at "HR_FORMAT, 6937 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()))); 6938 6939 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries. 6940 hr->add_strong_code_root_locked(_nm); 6941 } 6942 } 6943 6944 public: 6945 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 6946 _g1h(g1h), _nm(nm) {} 6947 6948 void do_oop(oop* p) { do_oop_work(p); } 6949 void do_oop(narrowOop* p) { do_oop_work(p); } 6950 }; 6951 6952 class UnregisterNMethodOopClosure: public OopClosure { 6953 G1CollectedHeap* _g1h; 6954 nmethod* _nm; 6955 6956 template <class T> void do_oop_work(T* p) { 6957 T heap_oop = oopDesc::load_heap_oop(p); 6958 if (!oopDesc::is_null(heap_oop)) { 6959 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 6960 HeapRegion* hr = _g1h->heap_region_containing(obj); 6961 assert(!hr->is_continues_humongous(), 6962 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT 6963 " starting at "HR_FORMAT, 6964 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()))); 6965 6966 hr->remove_strong_code_root(_nm); 6967 } 6968 } 6969 6970 public: 6971 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 6972 _g1h(g1h), _nm(nm) {} 6973 6974 void do_oop(oop* p) { do_oop_work(p); } 6975 void do_oop(narrowOop* p) { do_oop_work(p); } 6976 }; 6977 6978 void G1CollectedHeap::register_nmethod(nmethod* nm) { 6979 CollectedHeap::register_nmethod(nm); 6980 6981 guarantee(nm != NULL, "sanity"); 6982 RegisterNMethodOopClosure reg_cl(this, nm); 6983 nm->oops_do(®_cl); 6984 } 6985 6986 void G1CollectedHeap::unregister_nmethod(nmethod* nm) { 6987 CollectedHeap::unregister_nmethod(nm); 6988 6989 guarantee(nm != NULL, "sanity"); 6990 UnregisterNMethodOopClosure reg_cl(this, nm); 6991 nm->oops_do(®_cl, true); 6992 } 6993 6994 void G1CollectedHeap::purge_code_root_memory() { 6995 double purge_start = os::elapsedTime(); 6996 G1CodeRootSet::purge(); 6997 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0; 6998 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms); 6999 } 7000 7001 class RebuildStrongCodeRootClosure: public CodeBlobClosure { 7002 G1CollectedHeap* _g1h; 7003 7004 public: 7005 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) : 7006 _g1h(g1h) {} 7007 7008 void do_code_blob(CodeBlob* cb) { 7009 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL; 7010 if (nm == NULL) { 7011 return; 7012 } 7013 7014 if (ScavengeRootsInCode) { 7015 _g1h->register_nmethod(nm); 7016 } 7017 } 7018 }; 7019 7020 void G1CollectedHeap::rebuild_strong_code_roots() { 7021 RebuildStrongCodeRootClosure blob_cl(this); 7022 CodeCache::blobs_do(&blob_cl); 7023 } --- EOF ---