1 /* 2 * Copyright (c) 2001, 2014, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #if !defined(__clang_major__) && defined(__GNUC__) 26 #define ATTRIBUTE_PRINTF(x,y) // FIXME, formats are a mess. 27 #endif 28 29 #include "precompiled.hpp" 30 #include "code/codeCache.hpp" 31 #include "code/icBuffer.hpp" 32 #include "gc_implementation/g1/bufferingOopClosure.hpp" 33 #include "gc_implementation/g1/concurrentG1Refine.hpp" 34 #include "gc_implementation/g1/concurrentG1RefineThread.hpp" 35 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp" 36 #include "gc_implementation/g1/g1AllocRegion.inline.hpp" 37 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp" 38 #include "gc_implementation/g1/g1CollectorPolicy.hpp" 39 #include "gc_implementation/g1/g1ErgoVerbose.hpp" 40 #include "gc_implementation/g1/g1EvacFailure.hpp" 41 #include "gc_implementation/g1/g1GCPhaseTimes.hpp" 42 #include "gc_implementation/g1/g1Log.hpp" 43 #include "gc_implementation/g1/g1MarkSweep.hpp" 44 #include "gc_implementation/g1/g1OopClosures.inline.hpp" 45 #include "gc_implementation/g1/g1ParScanThreadState.inline.hpp" 46 #include "gc_implementation/g1/g1RegionToSpaceMapper.hpp" 47 #include "gc_implementation/g1/g1RemSet.inline.hpp" 48 #include "gc_implementation/g1/g1StringDedup.hpp" 49 #include "gc_implementation/g1/g1YCTypes.hpp" 50 #include "gc_implementation/g1/heapRegion.inline.hpp" 51 #include "gc_implementation/g1/heapRegionRemSet.hpp" 52 #include "gc_implementation/g1/heapRegionSet.inline.hpp" 53 #include "gc_implementation/g1/vm_operations_g1.hpp" 54 #include "gc_implementation/shared/gcHeapSummary.hpp" 55 #include "gc_implementation/shared/gcTimer.hpp" 56 #include "gc_implementation/shared/gcTrace.hpp" 57 #include "gc_implementation/shared/gcTraceTime.hpp" 58 #include "gc_implementation/shared/isGCActiveMark.hpp" 59 #include "memory/allocation.hpp" 60 #include "memory/gcLocker.inline.hpp" 61 #include "memory/generationSpec.hpp" 62 #include "memory/iterator.hpp" 63 #include "memory/referenceProcessor.hpp" 64 #include "oops/oop.inline.hpp" 65 #include "oops/oop.pcgc.inline.hpp" 66 #include "runtime/orderAccess.inline.hpp" 67 #include "runtime/vmThread.hpp" 68 69 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0; 70 71 // turn it on so that the contents of the young list (scan-only / 72 // to-be-collected) are printed at "strategic" points before / during 73 // / after the collection --- this is useful for debugging 74 #define YOUNG_LIST_VERBOSE 0 75 // CURRENT STATUS 76 // This file is under construction. Search for "FIXME". 77 78 // INVARIANTS/NOTES 79 // 80 // All allocation activity covered by the G1CollectedHeap interface is 81 // serialized by acquiring the HeapLock. This happens in mem_allocate 82 // and allocate_new_tlab, which are the "entry" points to the 83 // allocation code from the rest of the JVM. (Note that this does not 84 // apply to TLAB allocation, which is not part of this interface: it 85 // is done by clients of this interface.) 86 87 // Notes on implementation of parallelism in different tasks. 88 // 89 // G1ParVerifyTask uses heap_region_par_iterate_chunked() for parallelism. 90 // The number of GC workers is passed to heap_region_par_iterate_chunked(). 91 // It does use run_task() which sets _n_workers in the task. 92 // G1ParTask executes g1_process_roots() -> 93 // SharedHeap::process_roots() which calls eventually to 94 // CardTableModRefBS::par_non_clean_card_iterate_work() which uses 95 // SequentialSubTasksDone. SharedHeap::process_roots() also 96 // directly uses SubTasksDone (_process_strong_tasks field in SharedHeap). 97 // 98 99 // Local to this file. 100 101 class RefineCardTableEntryClosure: public CardTableEntryClosure { 102 bool _concurrent; 103 public: 104 RefineCardTableEntryClosure() : _concurrent(true) { } 105 106 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 107 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false); 108 // This path is executed by the concurrent refine or mutator threads, 109 // concurrently, and so we do not care if card_ptr contains references 110 // that point into the collection set. 111 assert(!oops_into_cset, "should be"); 112 113 if (_concurrent && SuspendibleThreadSet::should_yield()) { 114 // Caller will actually yield. 115 return false; 116 } 117 // Otherwise, we finished successfully; return true. 118 return true; 119 } 120 121 void set_concurrent(bool b) { _concurrent = b; } 122 }; 123 124 125 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure { 126 size_t _num_processed; 127 CardTableModRefBS* _ctbs; 128 int _histo[256]; 129 130 public: 131 ClearLoggedCardTableEntryClosure() : 132 _num_processed(0), _ctbs(G1CollectedHeap::heap()->g1_barrier_set()) 133 { 134 for (int i = 0; i < 256; i++) _histo[i] = 0; 135 } 136 137 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 138 unsigned char* ujb = (unsigned char*)card_ptr; 139 int ind = (int)(*ujb); 140 _histo[ind]++; 141 142 *card_ptr = (jbyte)CardTableModRefBS::clean_card_val(); 143 _num_processed++; 144 145 return true; 146 } 147 148 size_t num_processed() { return _num_processed; } 149 150 void print_histo() { 151 gclog_or_tty->print_cr("Card table value histogram:"); 152 for (int i = 0; i < 256; i++) { 153 if (_histo[i] != 0) { 154 gclog_or_tty->print_cr(" %d: %d", i, _histo[i]); 155 } 156 } 157 } 158 }; 159 160 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure { 161 private: 162 size_t _num_processed; 163 164 public: 165 RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { } 166 167 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 168 *card_ptr = CardTableModRefBS::dirty_card_val(); 169 _num_processed++; 170 return true; 171 } 172 173 size_t num_processed() const { return _num_processed; } 174 }; 175 176 YoungList::YoungList(G1CollectedHeap* g1h) : 177 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0), 178 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) { 179 guarantee(check_list_empty(false), "just making sure..."); 180 } 181 182 void YoungList::push_region(HeapRegion *hr) { 183 assert(!hr->is_young(), "should not already be young"); 184 assert(hr->get_next_young_region() == NULL, "cause it should!"); 185 186 hr->set_next_young_region(_head); 187 _head = hr; 188 189 _g1h->g1_policy()->set_region_eden(hr, (int) _length); 190 ++_length; 191 } 192 193 void YoungList::add_survivor_region(HeapRegion* hr) { 194 assert(hr->is_survivor(), "should be flagged as survivor region"); 195 assert(hr->get_next_young_region() == NULL, "cause it should!"); 196 197 hr->set_next_young_region(_survivor_head); 198 if (_survivor_head == NULL) { 199 _survivor_tail = hr; 200 } 201 _survivor_head = hr; 202 ++_survivor_length; 203 } 204 205 void YoungList::empty_list(HeapRegion* list) { 206 while (list != NULL) { 207 HeapRegion* next = list->get_next_young_region(); 208 list->set_next_young_region(NULL); 209 list->uninstall_surv_rate_group(); 210 list->set_not_young(); 211 list = next; 212 } 213 } 214 215 void YoungList::empty_list() { 216 assert(check_list_well_formed(), "young list should be well formed"); 217 218 empty_list(_head); 219 _head = NULL; 220 _length = 0; 221 222 empty_list(_survivor_head); 223 _survivor_head = NULL; 224 _survivor_tail = NULL; 225 _survivor_length = 0; 226 227 _last_sampled_rs_lengths = 0; 228 229 assert(check_list_empty(false), "just making sure..."); 230 } 231 232 bool YoungList::check_list_well_formed() { 233 bool ret = true; 234 235 uint length = 0; 236 HeapRegion* curr = _head; 237 HeapRegion* last = NULL; 238 while (curr != NULL) { 239 if (!curr->is_young()) { 240 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" " 241 "incorrectly tagged (y: %d, surv: %d)", 242 curr->bottom(), curr->end(), 243 curr->is_young(), curr->is_survivor()); 244 ret = false; 245 } 246 ++length; 247 last = curr; 248 curr = curr->get_next_young_region(); 249 } 250 ret = ret && (length == _length); 251 252 if (!ret) { 253 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!"); 254 gclog_or_tty->print_cr("### list has %u entries, _length is %u", 255 length, _length); 256 } 257 258 return ret; 259 } 260 261 bool YoungList::check_list_empty(bool check_sample) { 262 bool ret = true; 263 264 if (_length != 0) { 265 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u", 266 _length); 267 ret = false; 268 } 269 if (check_sample && _last_sampled_rs_lengths != 0) { 270 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths"); 271 ret = false; 272 } 273 if (_head != NULL) { 274 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head"); 275 ret = false; 276 } 277 if (!ret) { 278 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty"); 279 } 280 281 return ret; 282 } 283 284 void 285 YoungList::rs_length_sampling_init() { 286 _sampled_rs_lengths = 0; 287 _curr = _head; 288 } 289 290 bool 291 YoungList::rs_length_sampling_more() { 292 return _curr != NULL; 293 } 294 295 void 296 YoungList::rs_length_sampling_next() { 297 assert( _curr != NULL, "invariant" ); 298 size_t rs_length = _curr->rem_set()->occupied(); 299 300 _sampled_rs_lengths += rs_length; 301 302 // The current region may not yet have been added to the 303 // incremental collection set (it gets added when it is 304 // retired as the current allocation region). 305 if (_curr->in_collection_set()) { 306 // Update the collection set policy information for this region 307 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length); 308 } 309 310 _curr = _curr->get_next_young_region(); 311 if (_curr == NULL) { 312 _last_sampled_rs_lengths = _sampled_rs_lengths; 313 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths); 314 } 315 } 316 317 void 318 YoungList::reset_auxilary_lists() { 319 guarantee( is_empty(), "young list should be empty" ); 320 assert(check_list_well_formed(), "young list should be well formed"); 321 322 // Add survivor regions to SurvRateGroup. 323 _g1h->g1_policy()->note_start_adding_survivor_regions(); 324 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */); 325 326 int young_index_in_cset = 0; 327 for (HeapRegion* curr = _survivor_head; 328 curr != NULL; 329 curr = curr->get_next_young_region()) { 330 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset); 331 332 // The region is a non-empty survivor so let's add it to 333 // the incremental collection set for the next evacuation 334 // pause. 335 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr); 336 young_index_in_cset += 1; 337 } 338 assert((uint) young_index_in_cset == _survivor_length, "post-condition"); 339 _g1h->g1_policy()->note_stop_adding_survivor_regions(); 340 341 _head = _survivor_head; 342 _length = _survivor_length; 343 if (_survivor_head != NULL) { 344 assert(_survivor_tail != NULL, "cause it shouldn't be"); 345 assert(_survivor_length > 0, "invariant"); 346 _survivor_tail->set_next_young_region(NULL); 347 } 348 349 // Don't clear the survivor list handles until the start of 350 // the next evacuation pause - we need it in order to re-tag 351 // the survivor regions from this evacuation pause as 'young' 352 // at the start of the next. 353 354 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */); 355 356 assert(check_list_well_formed(), "young list should be well formed"); 357 } 358 359 void YoungList::print() { 360 HeapRegion* lists[] = {_head, _survivor_head}; 361 const char* names[] = {"YOUNG", "SURVIVOR"}; 362 363 for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) { 364 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]); 365 HeapRegion *curr = lists[list]; 366 if (curr == NULL) 367 gclog_or_tty->print_cr(" empty"); 368 while (curr != NULL) { 369 gclog_or_tty->print_cr(" "HR_FORMAT", P: "PTR_FORMAT "N: "PTR_FORMAT", age: %4d", 370 HR_FORMAT_PARAMS(curr), 371 curr->prev_top_at_mark_start(), 372 curr->next_top_at_mark_start(), 373 curr->age_in_surv_rate_group_cond()); 374 curr = curr->get_next_young_region(); 375 } 376 } 377 378 gclog_or_tty->cr(); 379 } 380 381 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) { 382 OtherRegionsTable::invalidate(start_idx, num_regions); 383 } 384 385 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions) { 386 reset_from_card_cache(start_idx, num_regions); 387 } 388 389 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr) 390 { 391 // Claim the right to put the region on the dirty cards region list 392 // by installing a self pointer. 393 HeapRegion* next = hr->get_next_dirty_cards_region(); 394 if (next == NULL) { 395 HeapRegion* res = (HeapRegion*) 396 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(), 397 NULL); 398 if (res == NULL) { 399 HeapRegion* head; 400 do { 401 // Put the region to the dirty cards region list. 402 head = _dirty_cards_region_list; 403 next = (HeapRegion*) 404 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head); 405 if (next == head) { 406 assert(hr->get_next_dirty_cards_region() == hr, 407 "hr->get_next_dirty_cards_region() != hr"); 408 if (next == NULL) { 409 // The last region in the list points to itself. 410 hr->set_next_dirty_cards_region(hr); 411 } else { 412 hr->set_next_dirty_cards_region(next); 413 } 414 } 415 } while (next != head); 416 } 417 } 418 } 419 420 HeapRegion* G1CollectedHeap::pop_dirty_cards_region() 421 { 422 HeapRegion* head; 423 HeapRegion* hr; 424 do { 425 head = _dirty_cards_region_list; 426 if (head == NULL) { 427 return NULL; 428 } 429 HeapRegion* new_head = head->get_next_dirty_cards_region(); 430 if (head == new_head) { 431 // The last region. 432 new_head = NULL; 433 } 434 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list, 435 head); 436 } while (hr != head); 437 assert(hr != NULL, "invariant"); 438 hr->set_next_dirty_cards_region(NULL); 439 return hr; 440 } 441 442 #ifdef ASSERT 443 // A region is added to the collection set as it is retired 444 // so an address p can point to a region which will be in the 445 // collection set but has not yet been retired. This method 446 // therefore is only accurate during a GC pause after all 447 // regions have been retired. It is used for debugging 448 // to check if an nmethod has references to objects that can 449 // be move during a partial collection. Though it can be 450 // inaccurate, it is sufficient for G1 because the conservative 451 // implementation of is_scavengable() for G1 will indicate that 452 // all nmethods must be scanned during a partial collection. 453 bool G1CollectedHeap::is_in_partial_collection(const void* p) { 454 if (p == NULL) { 455 return false; 456 } 457 return heap_region_containing(p)->in_collection_set(); 458 } 459 #endif 460 461 // Returns true if the reference points to an object that 462 // can move in an incremental collection. 463 bool G1CollectedHeap::is_scavengable(const void* p) { 464 HeapRegion* hr = heap_region_containing(p); 465 return !hr->isHumongous(); 466 } 467 468 void G1CollectedHeap::check_ct_logs_at_safepoint() { 469 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 470 CardTableModRefBS* ct_bs = g1_barrier_set(); 471 472 // Count the dirty cards at the start. 473 CountNonCleanMemRegionClosure count1(this); 474 ct_bs->mod_card_iterate(&count1); 475 int orig_count = count1.n(); 476 477 // First clear the logged cards. 478 ClearLoggedCardTableEntryClosure clear; 479 dcqs.apply_closure_to_all_completed_buffers(&clear); 480 dcqs.iterate_closure_all_threads(&clear, false); 481 clear.print_histo(); 482 483 // Now ensure that there's no dirty cards. 484 CountNonCleanMemRegionClosure count2(this); 485 ct_bs->mod_card_iterate(&count2); 486 if (count2.n() != 0) { 487 gclog_or_tty->print_cr("Card table has %d entries; %d originally", 488 count2.n(), orig_count); 489 } 490 guarantee(count2.n() == 0, "Card table should be clean."); 491 492 RedirtyLoggedCardTableEntryClosure redirty; 493 dcqs.apply_closure_to_all_completed_buffers(&redirty); 494 dcqs.iterate_closure_all_threads(&redirty, false); 495 gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.", 496 clear.num_processed(), orig_count); 497 guarantee(redirty.num_processed() == clear.num_processed(), 498 err_msg("Redirtied "SIZE_FORMAT" cards, bug cleared "SIZE_FORMAT, 499 redirty.num_processed(), clear.num_processed())); 500 501 CountNonCleanMemRegionClosure count3(this); 502 ct_bs->mod_card_iterate(&count3); 503 if (count3.n() != orig_count) { 504 gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.", 505 orig_count, count3.n()); 506 guarantee(count3.n() >= orig_count, "Should have restored them all."); 507 } 508 } 509 510 // Private class members. 511 512 G1CollectedHeap* G1CollectedHeap::_g1h; 513 514 // Private methods. 515 516 HeapRegion* 517 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) { 518 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 519 while (!_secondary_free_list.is_empty() || free_regions_coming()) { 520 if (!_secondary_free_list.is_empty()) { 521 if (G1ConcRegionFreeingVerbose) { 522 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 523 "secondary_free_list has %u entries", 524 _secondary_free_list.length()); 525 } 526 // It looks as if there are free regions available on the 527 // secondary_free_list. Let's move them to the free_list and try 528 // again to allocate from it. 529 append_secondary_free_list(); 530 531 assert(_hrs.num_free_regions() > 0, "if the secondary_free_list was not " 532 "empty we should have moved at least one entry to the free_list"); 533 HeapRegion* res = _hrs.allocate_free_region(is_old); 534 if (G1ConcRegionFreeingVerbose) { 535 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 536 "allocated "HR_FORMAT" from secondary_free_list", 537 HR_FORMAT_PARAMS(res)); 538 } 539 return res; 540 } 541 542 // Wait here until we get notified either when (a) there are no 543 // more free regions coming or (b) some regions have been moved on 544 // the secondary_free_list. 545 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 546 } 547 548 if (G1ConcRegionFreeingVerbose) { 549 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 550 "could not allocate from secondary_free_list"); 551 } 552 return NULL; 553 } 554 555 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) { 556 assert(!isHumongous(word_size) || word_size <= HeapRegion::GrainWords, 557 "the only time we use this to allocate a humongous region is " 558 "when we are allocating a single humongous region"); 559 560 HeapRegion* res; 561 if (G1StressConcRegionFreeing) { 562 if (!_secondary_free_list.is_empty()) { 563 if (G1ConcRegionFreeingVerbose) { 564 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 565 "forced to look at the secondary_free_list"); 566 } 567 res = new_region_try_secondary_free_list(is_old); 568 if (res != NULL) { 569 return res; 570 } 571 } 572 } 573 574 res = _hrs.allocate_free_region(is_old); 575 576 if (res == NULL) { 577 if (G1ConcRegionFreeingVerbose) { 578 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 579 "res == NULL, trying the secondary_free_list"); 580 } 581 res = new_region_try_secondary_free_list(is_old); 582 } 583 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) { 584 // Currently, only attempts to allocate GC alloc regions set 585 // do_expand to true. So, we should only reach here during a 586 // safepoint. If this assumption changes we might have to 587 // reconsider the use of _expand_heap_after_alloc_failure. 588 assert(SafepointSynchronize::is_at_safepoint(), "invariant"); 589 590 ergo_verbose1(ErgoHeapSizing, 591 "attempt heap expansion", 592 ergo_format_reason("region allocation request failed") 593 ergo_format_byte("allocation request"), 594 word_size * HeapWordSize); 595 if (expand(word_size * HeapWordSize)) { 596 // Given that expand() succeeded in expanding the heap, and we 597 // always expand the heap by an amount aligned to the heap 598 // region size, the free list should in theory not be empty. 599 // In either case allocate_free_region() will check for NULL. 600 res = _hrs.allocate_free_region(is_old); 601 } else { 602 _expand_heap_after_alloc_failure = false; 603 } 604 } 605 return res; 606 } 607 608 HeapWord* 609 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first, 610 uint num_regions, 611 size_t word_size) { 612 assert(first != G1_NO_HRS_INDEX, "pre-condition"); 613 assert(isHumongous(word_size), "word_size should be humongous"); 614 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition"); 615 616 // Index of last region in the series + 1. 617 uint last = first + num_regions; 618 619 // We need to initialize the region(s) we just discovered. This is 620 // a bit tricky given that it can happen concurrently with 621 // refinement threads refining cards on these regions and 622 // potentially wanting to refine the BOT as they are scanning 623 // those cards (this can happen shortly after a cleanup; see CR 624 // 6991377). So we have to set up the region(s) carefully and in 625 // a specific order. 626 627 // The word size sum of all the regions we will allocate. 628 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords; 629 assert(word_size <= word_size_sum, "sanity"); 630 631 // This will be the "starts humongous" region. 632 HeapRegion* first_hr = region_at(first); 633 // The header of the new object will be placed at the bottom of 634 // the first region. 635 HeapWord* new_obj = first_hr->bottom(); 636 // This will be the new end of the first region in the series that 637 // should also match the end of the last region in the series. 638 HeapWord* new_end = new_obj + word_size_sum; 639 // This will be the new top of the first region that will reflect 640 // this allocation. 641 HeapWord* new_top = new_obj + word_size; 642 643 // First, we need to zero the header of the space that we will be 644 // allocating. When we update top further down, some refinement 645 // threads might try to scan the region. By zeroing the header we 646 // ensure that any thread that will try to scan the region will 647 // come across the zero klass word and bail out. 648 // 649 // NOTE: It would not have been correct to have used 650 // CollectedHeap::fill_with_object() and make the space look like 651 // an int array. The thread that is doing the allocation will 652 // later update the object header to a potentially different array 653 // type and, for a very short period of time, the klass and length 654 // fields will be inconsistent. This could cause a refinement 655 // thread to calculate the object size incorrectly. 656 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0); 657 658 // We will set up the first region as "starts humongous". This 659 // will also update the BOT covering all the regions to reflect 660 // that there is a single object that starts at the bottom of the 661 // first region. 662 first_hr->set_startsHumongous(new_top, new_end); 663 664 // Then, if there are any, we will set up the "continues 665 // humongous" regions. 666 HeapRegion* hr = NULL; 667 for (uint i = first + 1; i < last; ++i) { 668 hr = region_at(i); 669 hr->set_continuesHumongous(first_hr); 670 } 671 // If we have "continues humongous" regions (hr != NULL), then the 672 // end of the last one should match new_end. 673 assert(hr == NULL || hr->end() == new_end, "sanity"); 674 675 // Up to this point no concurrent thread would have been able to 676 // do any scanning on any region in this series. All the top 677 // fields still point to bottom, so the intersection between 678 // [bottom,top] and [card_start,card_end] will be empty. Before we 679 // update the top fields, we'll do a storestore to make sure that 680 // no thread sees the update to top before the zeroing of the 681 // object header and the BOT initialization. 682 OrderAccess::storestore(); 683 684 // Now that the BOT and the object header have been initialized, 685 // we can update top of the "starts humongous" region. 686 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(), 687 "new_top should be in this region"); 688 first_hr->set_top(new_top); 689 if (_hr_printer.is_active()) { 690 HeapWord* bottom = first_hr->bottom(); 691 HeapWord* end = first_hr->orig_end(); 692 if ((first + 1) == last) { 693 // the series has a single humongous region 694 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top); 695 } else { 696 // the series has more than one humongous regions 697 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end); 698 } 699 } 700 701 // Now, we will update the top fields of the "continues humongous" 702 // regions. The reason we need to do this is that, otherwise, 703 // these regions would look empty and this will confuse parts of 704 // G1. For example, the code that looks for a consecutive number 705 // of empty regions will consider them empty and try to 706 // re-allocate them. We can extend is_empty() to also include 707 // !continuesHumongous(), but it is easier to just update the top 708 // fields here. The way we set top for all regions (i.e., top == 709 // end for all regions but the last one, top == new_top for the 710 // last one) is actually used when we will free up the humongous 711 // region in free_humongous_region(). 712 hr = NULL; 713 for (uint i = first + 1; i < last; ++i) { 714 hr = region_at(i); 715 if ((i + 1) == last) { 716 // last continues humongous region 717 assert(hr->bottom() < new_top && new_top <= hr->end(), 718 "new_top should fall on this region"); 719 hr->set_top(new_top); 720 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top); 721 } else { 722 // not last one 723 assert(new_top > hr->end(), "new_top should be above this region"); 724 hr->set_top(hr->end()); 725 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end()); 726 } 727 } 728 // If we have continues humongous regions (hr != NULL), then the 729 // end of the last one should match new_end and its top should 730 // match new_top. 731 assert(hr == NULL || 732 (hr->end() == new_end && hr->top() == new_top), "sanity"); 733 check_bitmaps("Humongous Region Allocation", first_hr); 734 735 assert(first_hr->used() == word_size * HeapWordSize, "invariant"); 736 _summary_bytes_used += first_hr->used(); 737 _humongous_set.add(first_hr); 738 739 return new_obj; 740 } 741 742 // If could fit into free regions w/o expansion, try. 743 // Otherwise, if can expand, do so. 744 // Otherwise, if using ex regions might help, try with ex given back. 745 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) { 746 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 747 748 verify_region_sets_optional(); 749 750 uint first = G1_NO_HRS_INDEX; 751 uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords); 752 753 if (obj_regions == 1) { 754 // Only one region to allocate, try to use a fast path by directly allocating 755 // from the free lists. Do not try to expand here, we will potentially do that 756 // later. 757 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */); 758 if (hr != NULL) { 759 first = hr->hrs_index(); 760 } 761 } else { 762 // We can't allocate humongous regions spanning more than one region while 763 // cleanupComplete() is running, since some of the regions we find to be 764 // empty might not yet be added to the free list. It is not straightforward 765 // to know in which list they are on so that we can remove them. We only 766 // need to do this if we need to allocate more than one region to satisfy the 767 // current humongous allocation request. If we are only allocating one region 768 // we use the one-region region allocation code (see above), that already 769 // potentially waits for regions from the secondary free list. 770 wait_while_free_regions_coming(); 771 append_secondary_free_list_if_not_empty_with_lock(); 772 773 // Policy: Try only empty regions (i.e. already committed first). Maybe we 774 // are lucky enough to find some. 775 first = _hrs.find_contiguous_only_empty(obj_regions); 776 if (first != G1_NO_HRS_INDEX) { 777 _hrs.allocate_free_regions_starting_at(first, obj_regions); 778 } 779 } 780 781 if (first == G1_NO_HRS_INDEX) { 782 // Policy: We could not find enough regions for the humongous object in the 783 // free list. Look through the heap to find a mix of free and uncommitted regions. 784 // If so, try expansion. 785 first = _hrs.find_contiguous_empty_or_unavailable(obj_regions); 786 if (first != G1_NO_HRS_INDEX) { 787 // We found something. Make sure these regions are committed, i.e. expand 788 // the heap. Alternatively we could do a defragmentation GC. 789 ergo_verbose1(ErgoHeapSizing, 790 "attempt heap expansion", 791 ergo_format_reason("humongous allocation request failed") 792 ergo_format_byte("allocation request"), 793 word_size * HeapWordSize); 794 795 _hrs.expand_at(first, obj_regions); 796 g1_policy()->record_new_heap_size(num_regions()); 797 798 #ifdef ASSERT 799 for (uint i = first; i < first + obj_regions; ++i) { 800 HeapRegion* hr = region_at(i); 801 assert(hr->is_empty(), "sanity"); 802 assert(is_on_master_free_list(hr), "sanity"); 803 } 804 #endif 805 _hrs.allocate_free_regions_starting_at(first, obj_regions); 806 } else { 807 // Policy: Potentially trigger a defragmentation GC. 808 } 809 } 810 811 HeapWord* result = NULL; 812 if (first != G1_NO_HRS_INDEX) { 813 result = humongous_obj_allocate_initialize_regions(first, obj_regions, word_size); 814 assert(result != NULL, "it should always return a valid result"); 815 816 // A successful humongous object allocation changes the used space 817 // information of the old generation so we need to recalculate the 818 // sizes and update the jstat counters here. 819 g1mm()->update_sizes(); 820 } 821 822 verify_region_sets_optional(); 823 824 return result; 825 } 826 827 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) { 828 assert_heap_not_locked_and_not_at_safepoint(); 829 assert(!isHumongous(word_size), "we do not allow humongous TLABs"); 830 831 unsigned int dummy_gc_count_before; 832 int dummy_gclocker_retry_count = 0; 833 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count); 834 } 835 836 HeapWord* 837 G1CollectedHeap::mem_allocate(size_t word_size, 838 bool* gc_overhead_limit_was_exceeded) { 839 assert_heap_not_locked_and_not_at_safepoint(); 840 841 // Loop until the allocation is satisfied, or unsatisfied after GC. 842 for (int try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 843 unsigned int gc_count_before; 844 845 HeapWord* result = NULL; 846 if (!isHumongous(word_size)) { 847 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count); 848 } else { 849 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count); 850 } 851 if (result != NULL) { 852 return result; 853 } 854 855 // Create the garbage collection operation... 856 VM_G1CollectForAllocation op(gc_count_before, word_size); 857 // ...and get the VM thread to execute it. 858 VMThread::execute(&op); 859 860 if (op.prologue_succeeded() && op.pause_succeeded()) { 861 // If the operation was successful we'll return the result even 862 // if it is NULL. If the allocation attempt failed immediately 863 // after a Full GC, it's unlikely we'll be able to allocate now. 864 HeapWord* result = op.result(); 865 if (result != NULL && !isHumongous(word_size)) { 866 // Allocations that take place on VM operations do not do any 867 // card dirtying and we have to do it here. We only have to do 868 // this for non-humongous allocations, though. 869 dirty_young_block(result, word_size); 870 } 871 return result; 872 } else { 873 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 874 return NULL; 875 } 876 assert(op.result() == NULL, 877 "the result should be NULL if the VM op did not succeed"); 878 } 879 880 // Give a warning if we seem to be looping forever. 881 if ((QueuedAllocationWarningCount > 0) && 882 (try_count % QueuedAllocationWarningCount == 0)) { 883 warning("G1CollectedHeap::mem_allocate retries %d times", try_count); 884 } 885 } 886 887 ShouldNotReachHere(); 888 return NULL; 889 } 890 891 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size, 892 unsigned int *gc_count_before_ret, 893 int* gclocker_retry_count_ret) { 894 // Make sure you read the note in attempt_allocation_humongous(). 895 896 assert_heap_not_locked_and_not_at_safepoint(); 897 assert(!isHumongous(word_size), "attempt_allocation_slow() should not " 898 "be called for humongous allocation requests"); 899 900 // We should only get here after the first-level allocation attempt 901 // (attempt_allocation()) failed to allocate. 902 903 // We will loop until a) we manage to successfully perform the 904 // allocation or b) we successfully schedule a collection which 905 // fails to perform the allocation. b) is the only case when we'll 906 // return NULL. 907 HeapWord* result = NULL; 908 for (int try_count = 1; /* we'll return */; try_count += 1) { 909 bool should_try_gc; 910 unsigned int gc_count_before; 911 912 { 913 MutexLockerEx x(Heap_lock); 914 915 result = _mutator_alloc_region.attempt_allocation_locked(word_size, 916 false /* bot_updates */); 917 if (result != NULL) { 918 return result; 919 } 920 921 // If we reach here, attempt_allocation_locked() above failed to 922 // allocate a new region. So the mutator alloc region should be NULL. 923 assert(_mutator_alloc_region.get() == NULL, "only way to get here"); 924 925 if (GC_locker::is_active_and_needs_gc()) { 926 if (g1_policy()->can_expand_young_list()) { 927 // No need for an ergo verbose message here, 928 // can_expand_young_list() does this when it returns true. 929 result = _mutator_alloc_region.attempt_allocation_force(word_size, 930 false /* bot_updates */); 931 if (result != NULL) { 932 return result; 933 } 934 } 935 should_try_gc = false; 936 } else { 937 // The GCLocker may not be active but the GCLocker initiated 938 // GC may not yet have been performed (GCLocker::needs_gc() 939 // returns true). In this case we do not try this GC and 940 // wait until the GCLocker initiated GC is performed, and 941 // then retry the allocation. 942 if (GC_locker::needs_gc()) { 943 should_try_gc = false; 944 } else { 945 // Read the GC count while still holding the Heap_lock. 946 gc_count_before = total_collections(); 947 should_try_gc = true; 948 } 949 } 950 } 951 952 if (should_try_gc) { 953 bool succeeded; 954 result = do_collection_pause(word_size, gc_count_before, &succeeded, 955 GCCause::_g1_inc_collection_pause); 956 if (result != NULL) { 957 assert(succeeded, "only way to get back a non-NULL result"); 958 return result; 959 } 960 961 if (succeeded) { 962 // If we get here we successfully scheduled a collection which 963 // failed to allocate. No point in trying to allocate 964 // further. We'll just return NULL. 965 MutexLockerEx x(Heap_lock); 966 *gc_count_before_ret = total_collections(); 967 return NULL; 968 } 969 } else { 970 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { 971 MutexLockerEx x(Heap_lock); 972 *gc_count_before_ret = total_collections(); 973 return NULL; 974 } 975 // The GCLocker is either active or the GCLocker initiated 976 // GC has not yet been performed. Stall until it is and 977 // then retry the allocation. 978 GC_locker::stall_until_clear(); 979 (*gclocker_retry_count_ret) += 1; 980 } 981 982 // We can reach here if we were unsuccessful in scheduling a 983 // collection (because another thread beat us to it) or if we were 984 // stalled due to the GC locker. In either can we should retry the 985 // allocation attempt in case another thread successfully 986 // performed a collection and reclaimed enough space. We do the 987 // first attempt (without holding the Heap_lock) here and the 988 // follow-on attempt will be at the start of the next loop 989 // iteration (after taking the Heap_lock). 990 result = _mutator_alloc_region.attempt_allocation(word_size, 991 false /* bot_updates */); 992 if (result != NULL) { 993 return result; 994 } 995 996 // Give a warning if we seem to be looping forever. 997 if ((QueuedAllocationWarningCount > 0) && 998 (try_count % QueuedAllocationWarningCount == 0)) { 999 warning("G1CollectedHeap::attempt_allocation_slow() " 1000 "retries %d times", try_count); 1001 } 1002 } 1003 1004 ShouldNotReachHere(); 1005 return NULL; 1006 } 1007 1008 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size, 1009 unsigned int * gc_count_before_ret, 1010 int* gclocker_retry_count_ret) { 1011 // The structure of this method has a lot of similarities to 1012 // attempt_allocation_slow(). The reason these two were not merged 1013 // into a single one is that such a method would require several "if 1014 // allocation is not humongous do this, otherwise do that" 1015 // conditional paths which would obscure its flow. In fact, an early 1016 // version of this code did use a unified method which was harder to 1017 // follow and, as a result, it had subtle bugs that were hard to 1018 // track down. So keeping these two methods separate allows each to 1019 // be more readable. It will be good to keep these two in sync as 1020 // much as possible. 1021 1022 assert_heap_not_locked_and_not_at_safepoint(); 1023 assert(isHumongous(word_size), "attempt_allocation_humongous() " 1024 "should only be called for humongous allocations"); 1025 1026 // Humongous objects can exhaust the heap quickly, so we should check if we 1027 // need to start a marking cycle at each humongous object allocation. We do 1028 // the check before we do the actual allocation. The reason for doing it 1029 // before the allocation is that we avoid having to keep track of the newly 1030 // allocated memory while we do a GC. 1031 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation", 1032 word_size)) { 1033 collect(GCCause::_g1_humongous_allocation); 1034 } 1035 1036 // We will loop until a) we manage to successfully perform the 1037 // allocation or b) we successfully schedule a collection which 1038 // fails to perform the allocation. b) is the only case when we'll 1039 // return NULL. 1040 HeapWord* result = NULL; 1041 for (int try_count = 1; /* we'll return */; try_count += 1) { 1042 bool should_try_gc; 1043 unsigned int gc_count_before; 1044 1045 { 1046 MutexLockerEx x(Heap_lock); 1047 1048 // Given that humongous objects are not allocated in young 1049 // regions, we'll first try to do the allocation without doing a 1050 // collection hoping that there's enough space in the heap. 1051 result = humongous_obj_allocate(word_size); 1052 if (result != NULL) { 1053 return result; 1054 } 1055 1056 if (GC_locker::is_active_and_needs_gc()) { 1057 should_try_gc = false; 1058 } else { 1059 // The GCLocker may not be active but the GCLocker initiated 1060 // GC may not yet have been performed (GCLocker::needs_gc() 1061 // returns true). In this case we do not try this GC and 1062 // wait until the GCLocker initiated GC is performed, and 1063 // then retry the allocation. 1064 if (GC_locker::needs_gc()) { 1065 should_try_gc = false; 1066 } else { 1067 // Read the GC count while still holding the Heap_lock. 1068 gc_count_before = total_collections(); 1069 should_try_gc = true; 1070 } 1071 } 1072 } 1073 1074 if (should_try_gc) { 1075 // If we failed to allocate the humongous object, we should try to 1076 // do a collection pause (if we're allowed) in case it reclaims 1077 // enough space for the allocation to succeed after the pause. 1078 1079 bool succeeded; 1080 result = do_collection_pause(word_size, gc_count_before, &succeeded, 1081 GCCause::_g1_humongous_allocation); 1082 if (result != NULL) { 1083 assert(succeeded, "only way to get back a non-NULL result"); 1084 return result; 1085 } 1086 1087 if (succeeded) { 1088 // If we get here we successfully scheduled a collection which 1089 // failed to allocate. No point in trying to allocate 1090 // further. We'll just return NULL. 1091 MutexLockerEx x(Heap_lock); 1092 *gc_count_before_ret = total_collections(); 1093 return NULL; 1094 } 1095 } else { 1096 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { 1097 MutexLockerEx x(Heap_lock); 1098 *gc_count_before_ret = total_collections(); 1099 return NULL; 1100 } 1101 // The GCLocker is either active or the GCLocker initiated 1102 // GC has not yet been performed. Stall until it is and 1103 // then retry the allocation. 1104 GC_locker::stall_until_clear(); 1105 (*gclocker_retry_count_ret) += 1; 1106 } 1107 1108 // We can reach here if we were unsuccessful in scheduling a 1109 // collection (because another thread beat us to it) or if we were 1110 // stalled due to the GC locker. In either can we should retry the 1111 // allocation attempt in case another thread successfully 1112 // performed a collection and reclaimed enough space. Give a 1113 // warning if we seem to be looping forever. 1114 1115 if ((QueuedAllocationWarningCount > 0) && 1116 (try_count % QueuedAllocationWarningCount == 0)) { 1117 warning("G1CollectedHeap::attempt_allocation_humongous() " 1118 "retries %d times", try_count); 1119 } 1120 } 1121 1122 ShouldNotReachHere(); 1123 return NULL; 1124 } 1125 1126 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size, 1127 bool expect_null_mutator_alloc_region) { 1128 assert_at_safepoint(true /* should_be_vm_thread */); 1129 assert(_mutator_alloc_region.get() == NULL || 1130 !expect_null_mutator_alloc_region, 1131 "the current alloc region was unexpectedly found to be non-NULL"); 1132 1133 if (!isHumongous(word_size)) { 1134 return _mutator_alloc_region.attempt_allocation_locked(word_size, 1135 false /* bot_updates */); 1136 } else { 1137 HeapWord* result = humongous_obj_allocate(word_size); 1138 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) { 1139 g1_policy()->set_initiate_conc_mark_if_possible(); 1140 } 1141 return result; 1142 } 1143 1144 ShouldNotReachHere(); 1145 } 1146 1147 class PostMCRemSetClearClosure: public HeapRegionClosure { 1148 G1CollectedHeap* _g1h; 1149 ModRefBarrierSet* _mr_bs; 1150 public: 1151 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) : 1152 _g1h(g1h), _mr_bs(mr_bs) {} 1153 1154 bool doHeapRegion(HeapRegion* r) { 1155 HeapRegionRemSet* hrrs = r->rem_set(); 1156 1157 if (r->continuesHumongous()) { 1158 // We'll assert that the strong code root list and RSet is empty 1159 assert(hrrs->strong_code_roots_list_length() == 0, "sanity"); 1160 assert(hrrs->occupied() == 0, "RSet should be empty"); 1161 return false; 1162 } 1163 1164 _g1h->reset_gc_time_stamps(r); 1165 hrrs->clear(); 1166 // You might think here that we could clear just the cards 1167 // corresponding to the used region. But no: if we leave a dirty card 1168 // in a region we might allocate into, then it would prevent that card 1169 // from being enqueued, and cause it to be missed. 1170 // Re: the performance cost: we shouldn't be doing full GC anyway! 1171 _mr_bs->clear(MemRegion(r->bottom(), r->end())); 1172 1173 return false; 1174 } 1175 }; 1176 1177 void G1CollectedHeap::clear_rsets_post_compaction() { 1178 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set()); 1179 heap_region_iterate(&rs_clear); 1180 } 1181 1182 class RebuildRSOutOfRegionClosure: public HeapRegionClosure { 1183 G1CollectedHeap* _g1h; 1184 UpdateRSOopClosure _cl; 1185 int _worker_i; 1186 public: 1187 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) : 1188 _cl(g1->g1_rem_set(), worker_i), 1189 _worker_i(worker_i), 1190 _g1h(g1) 1191 { } 1192 1193 bool doHeapRegion(HeapRegion* r) { 1194 if (!r->continuesHumongous()) { 1195 _cl.set_from(r); 1196 r->oop_iterate(&_cl); 1197 } 1198 return false; 1199 } 1200 }; 1201 1202 class ParRebuildRSTask: public AbstractGangTask { 1203 G1CollectedHeap* _g1; 1204 public: 1205 ParRebuildRSTask(G1CollectedHeap* g1) 1206 : AbstractGangTask("ParRebuildRSTask"), 1207 _g1(g1) 1208 { } 1209 1210 void work(uint worker_id) { 1211 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id); 1212 _g1->heap_region_par_iterate_chunked(&rebuild_rs, worker_id, 1213 _g1->workers()->active_workers(), 1214 HeapRegion::RebuildRSClaimValue); 1215 } 1216 }; 1217 1218 class PostCompactionPrinterClosure: public HeapRegionClosure { 1219 private: 1220 G1HRPrinter* _hr_printer; 1221 public: 1222 bool doHeapRegion(HeapRegion* hr) { 1223 assert(!hr->is_young(), "not expecting to find young regions"); 1224 // We only generate output for non-empty regions. 1225 if (!hr->is_empty()) { 1226 if (!hr->isHumongous()) { 1227 _hr_printer->post_compaction(hr, G1HRPrinter::Old); 1228 } else if (hr->startsHumongous()) { 1229 if (hr->region_num() == 1) { 1230 // single humongous region 1231 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous); 1232 } else { 1233 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous); 1234 } 1235 } else { 1236 assert(hr->continuesHumongous(), "only way to get here"); 1237 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous); 1238 } 1239 } 1240 return false; 1241 } 1242 1243 PostCompactionPrinterClosure(G1HRPrinter* hr_printer) 1244 : _hr_printer(hr_printer) { } 1245 }; 1246 1247 void G1CollectedHeap::print_hrs_post_compaction() { 1248 PostCompactionPrinterClosure cl(hr_printer()); 1249 heap_region_iterate(&cl); 1250 } 1251 1252 bool G1CollectedHeap::do_collection(bool explicit_gc, 1253 bool clear_all_soft_refs, 1254 size_t word_size) { 1255 assert_at_safepoint(true /* should_be_vm_thread */); 1256 1257 if (GC_locker::check_active_before_gc()) { 1258 return false; 1259 } 1260 1261 STWGCTimer* gc_timer = G1MarkSweep::gc_timer(); 1262 gc_timer->register_gc_start(); 1263 1264 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer(); 1265 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start()); 1266 1267 SvcGCMarker sgcm(SvcGCMarker::FULL); 1268 ResourceMark rm; 1269 1270 print_heap_before_gc(); 1271 trace_heap_before_gc(gc_tracer); 1272 1273 size_t metadata_prev_used = MetaspaceAux::used_bytes(); 1274 1275 verify_region_sets_optional(); 1276 1277 const bool do_clear_all_soft_refs = clear_all_soft_refs || 1278 collector_policy()->should_clear_all_soft_refs(); 1279 1280 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy()); 1281 1282 { 1283 IsGCActiveMark x; 1284 1285 // Timing 1286 assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant"); 1287 gclog_or_tty->date_stamp(G1Log::fine() && PrintGCDateStamps); 1288 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty); 1289 1290 { 1291 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL, gc_tracer->gc_id()); 1292 TraceCollectorStats tcs(g1mm()->full_collection_counters()); 1293 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause()); 1294 1295 double start = os::elapsedTime(); 1296 g1_policy()->record_full_collection_start(); 1297 1298 // Note: When we have a more flexible GC logging framework that 1299 // allows us to add optional attributes to a GC log record we 1300 // could consider timing and reporting how long we wait in the 1301 // following two methods. 1302 wait_while_free_regions_coming(); 1303 // If we start the compaction before the CM threads finish 1304 // scanning the root regions we might trip them over as we'll 1305 // be moving objects / updating references. So let's wait until 1306 // they are done. By telling them to abort, they should complete 1307 // early. 1308 _cm->root_regions()->abort(); 1309 _cm->root_regions()->wait_until_scan_finished(); 1310 append_secondary_free_list_if_not_empty_with_lock(); 1311 1312 gc_prologue(true); 1313 increment_total_collections(true /* full gc */); 1314 increment_old_marking_cycles_started(); 1315 1316 assert(used() == recalculate_used(), "Should be equal"); 1317 1318 verify_before_gc(); 1319 1320 check_bitmaps("Full GC Start"); 1321 pre_full_gc_dump(gc_timer); 1322 1323 COMPILER2_PRESENT(DerivedPointerTable::clear()); 1324 1325 // Disable discovery and empty the discovered lists 1326 // for the CM ref processor. 1327 ref_processor_cm()->disable_discovery(); 1328 ref_processor_cm()->abandon_partial_discovery(); 1329 ref_processor_cm()->verify_no_references_recorded(); 1330 1331 // Abandon current iterations of concurrent marking and concurrent 1332 // refinement, if any are in progress. We have to do this before 1333 // wait_until_scan_finished() below. 1334 concurrent_mark()->abort(); 1335 1336 // Make sure we'll choose a new allocation region afterwards. 1337 release_mutator_alloc_region(); 1338 abandon_gc_alloc_regions(); 1339 g1_rem_set()->cleanupHRRS(); 1340 1341 // We should call this after we retire any currently active alloc 1342 // regions so that all the ALLOC / RETIRE events are generated 1343 // before the start GC event. 1344 _hr_printer.start_gc(true /* full */, (size_t) total_collections()); 1345 1346 // We may have added regions to the current incremental collection 1347 // set between the last GC or pause and now. We need to clear the 1348 // incremental collection set and then start rebuilding it afresh 1349 // after this full GC. 1350 abandon_collection_set(g1_policy()->inc_cset_head()); 1351 g1_policy()->clear_incremental_cset(); 1352 g1_policy()->stop_incremental_cset_building(); 1353 1354 tear_down_region_sets(false /* free_list_only */); 1355 g1_policy()->set_gcs_are_young(true); 1356 1357 // See the comments in g1CollectedHeap.hpp and 1358 // G1CollectedHeap::ref_processing_init() about 1359 // how reference processing currently works in G1. 1360 1361 // Temporarily make discovery by the STW ref processor single threaded (non-MT). 1362 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false); 1363 1364 // Temporarily clear the STW ref processor's _is_alive_non_header field. 1365 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL); 1366 1367 ref_processor_stw()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/); 1368 ref_processor_stw()->setup_policy(do_clear_all_soft_refs); 1369 1370 // Do collection work 1371 { 1372 HandleMark hm; // Discard invalid handles created during gc 1373 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs); 1374 } 1375 1376 assert(num_free_regions() == 0, "we should not have added any free regions"); 1377 rebuild_region_sets(false /* free_list_only */); 1378 1379 // Enqueue any discovered reference objects that have 1380 // not been removed from the discovered lists. 1381 ref_processor_stw()->enqueue_discovered_references(); 1382 1383 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 1384 1385 MemoryService::track_memory_usage(); 1386 1387 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 1388 ref_processor_stw()->verify_no_references_recorded(); 1389 1390 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 1391 ClassLoaderDataGraph::purge(); 1392 MetaspaceAux::verify_metrics(); 1393 1394 // Note: since we've just done a full GC, concurrent 1395 // marking is no longer active. Therefore we need not 1396 // re-enable reference discovery for the CM ref processor. 1397 // That will be done at the start of the next marking cycle. 1398 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition"); 1399 ref_processor_cm()->verify_no_references_recorded(); 1400 1401 reset_gc_time_stamp(); 1402 // Since everything potentially moved, we will clear all remembered 1403 // sets, and clear all cards. Later we will rebuild remembered 1404 // sets. We will also reset the GC time stamps of the regions. 1405 clear_rsets_post_compaction(); 1406 check_gc_time_stamps(); 1407 1408 // Resize the heap if necessary. 1409 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size); 1410 1411 if (_hr_printer.is_active()) { 1412 // We should do this after we potentially resize the heap so 1413 // that all the COMMIT / UNCOMMIT events are generated before 1414 // the end GC event. 1415 1416 print_hrs_post_compaction(); 1417 _hr_printer.end_gc(true /* full */, (size_t) total_collections()); 1418 } 1419 1420 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 1421 if (hot_card_cache->use_cache()) { 1422 hot_card_cache->reset_card_counts(); 1423 hot_card_cache->reset_hot_cache(); 1424 } 1425 1426 // Rebuild remembered sets of all regions. 1427 if (G1CollectedHeap::use_parallel_gc_threads()) { 1428 uint n_workers = 1429 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 1430 workers()->active_workers(), 1431 Threads::number_of_non_daemon_threads()); 1432 assert(UseDynamicNumberOfGCThreads || 1433 n_workers == workers()->total_workers(), 1434 "If not dynamic should be using all the workers"); 1435 workers()->set_active_workers(n_workers); 1436 // Set parallel threads in the heap (_n_par_threads) only 1437 // before a parallel phase and always reset it to 0 after 1438 // the phase so that the number of parallel threads does 1439 // no get carried forward to a serial phase where there 1440 // may be code that is "possibly_parallel". 1441 set_par_threads(n_workers); 1442 1443 ParRebuildRSTask rebuild_rs_task(this); 1444 assert(check_heap_region_claim_values( 1445 HeapRegion::InitialClaimValue), "sanity check"); 1446 assert(UseDynamicNumberOfGCThreads || 1447 workers()->active_workers() == workers()->total_workers(), 1448 "Unless dynamic should use total workers"); 1449 // Use the most recent number of active workers 1450 assert(workers()->active_workers() > 0, 1451 "Active workers not properly set"); 1452 set_par_threads(workers()->active_workers()); 1453 workers()->run_task(&rebuild_rs_task); 1454 set_par_threads(0); 1455 assert(check_heap_region_claim_values( 1456 HeapRegion::RebuildRSClaimValue), "sanity check"); 1457 reset_heap_region_claim_values(); 1458 } else { 1459 RebuildRSOutOfRegionClosure rebuild_rs(this); 1460 heap_region_iterate(&rebuild_rs); 1461 } 1462 1463 // Rebuild the strong code root lists for each region 1464 rebuild_strong_code_roots(); 1465 1466 if (true) { // FIXME 1467 MetaspaceGC::compute_new_size(); 1468 } 1469 1470 #ifdef TRACESPINNING 1471 ParallelTaskTerminator::print_termination_counts(); 1472 #endif 1473 1474 // Discard all rset updates 1475 JavaThread::dirty_card_queue_set().abandon_logs(); 1476 assert(!G1DeferredRSUpdate 1477 || (G1DeferredRSUpdate && 1478 (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any"); 1479 1480 _young_list->reset_sampled_info(); 1481 // At this point there should be no regions in the 1482 // entire heap tagged as young. 1483 assert(check_young_list_empty(true /* check_heap */), 1484 "young list should be empty at this point"); 1485 1486 // Update the number of full collections that have been completed. 1487 increment_old_marking_cycles_completed(false /* concurrent */); 1488 1489 _hrs.verify_optional(); 1490 verify_region_sets_optional(); 1491 1492 verify_after_gc(); 1493 1494 // Clear the previous marking bitmap, if needed for bitmap verification. 1495 // Note we cannot do this when we clear the next marking bitmap in 1496 // ConcurrentMark::abort() above since VerifyDuringGC verifies the 1497 // objects marked during a full GC against the previous bitmap. 1498 // But we need to clear it before calling check_bitmaps below since 1499 // the full GC has compacted objects and updated TAMS but not updated 1500 // the prev bitmap. 1501 if (G1VerifyBitmaps) { 1502 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll(); 1503 } 1504 check_bitmaps("Full GC End"); 1505 1506 // Start a new incremental collection set for the next pause 1507 assert(g1_policy()->collection_set() == NULL, "must be"); 1508 g1_policy()->start_incremental_cset_building(); 1509 1510 clear_cset_fast_test(); 1511 1512 init_mutator_alloc_region(); 1513 1514 double end = os::elapsedTime(); 1515 g1_policy()->record_full_collection_end(); 1516 1517 if (G1Log::fine()) { 1518 g1_policy()->print_heap_transition(); 1519 } 1520 1521 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 1522 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 1523 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 1524 // before any GC notifications are raised. 1525 g1mm()->update_sizes(); 1526 1527 gc_epilogue(true); 1528 } 1529 1530 if (G1Log::finer()) { 1531 g1_policy()->print_detailed_heap_transition(true /* full */); 1532 } 1533 1534 print_heap_after_gc(); 1535 trace_heap_after_gc(gc_tracer); 1536 1537 post_full_gc_dump(gc_timer); 1538 1539 gc_timer->register_gc_end(); 1540 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions()); 1541 } 1542 1543 return true; 1544 } 1545 1546 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) { 1547 // do_collection() will return whether it succeeded in performing 1548 // the GC. Currently, there is no facility on the 1549 // do_full_collection() API to notify the caller than the collection 1550 // did not succeed (e.g., because it was locked out by the GC 1551 // locker). So, right now, we'll ignore the return value. 1552 bool dummy = do_collection(true, /* explicit_gc */ 1553 clear_all_soft_refs, 1554 0 /* word_size */); 1555 } 1556 1557 // This code is mostly copied from TenuredGeneration. 1558 void 1559 G1CollectedHeap:: 1560 resize_if_necessary_after_full_collection(size_t word_size) { 1561 // Include the current allocation, if any, and bytes that will be 1562 // pre-allocated to support collections, as "used". 1563 const size_t used_after_gc = used(); 1564 const size_t capacity_after_gc = capacity(); 1565 const size_t free_after_gc = capacity_after_gc - used_after_gc; 1566 1567 // This is enforced in arguments.cpp. 1568 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, 1569 "otherwise the code below doesn't make sense"); 1570 1571 // We don't have floating point command-line arguments 1572 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0; 1573 const double maximum_used_percentage = 1.0 - minimum_free_percentage; 1574 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0; 1575 const double minimum_used_percentage = 1.0 - maximum_free_percentage; 1576 1577 const size_t min_heap_size = collector_policy()->min_heap_byte_size(); 1578 const size_t max_heap_size = collector_policy()->max_heap_byte_size(); 1579 1580 // We have to be careful here as these two calculations can overflow 1581 // 32-bit size_t's. 1582 double used_after_gc_d = (double) used_after_gc; 1583 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage; 1584 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage; 1585 1586 // Let's make sure that they are both under the max heap size, which 1587 // by default will make them fit into a size_t. 1588 double desired_capacity_upper_bound = (double) max_heap_size; 1589 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d, 1590 desired_capacity_upper_bound); 1591 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d, 1592 desired_capacity_upper_bound); 1593 1594 // We can now safely turn them into size_t's. 1595 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d; 1596 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d; 1597 1598 // This assert only makes sense here, before we adjust them 1599 // with respect to the min and max heap size. 1600 assert(minimum_desired_capacity <= maximum_desired_capacity, 1601 err_msg("minimum_desired_capacity = "SIZE_FORMAT", " 1602 "maximum_desired_capacity = "SIZE_FORMAT, 1603 minimum_desired_capacity, maximum_desired_capacity)); 1604 1605 // Should not be greater than the heap max size. No need to adjust 1606 // it with respect to the heap min size as it's a lower bound (i.e., 1607 // we'll try to make the capacity larger than it, not smaller). 1608 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size); 1609 // Should not be less than the heap min size. No need to adjust it 1610 // with respect to the heap max size as it's an upper bound (i.e., 1611 // we'll try to make the capacity smaller than it, not greater). 1612 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size); 1613 1614 if (capacity_after_gc < minimum_desired_capacity) { 1615 // Don't expand unless it's significant 1616 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc; 1617 ergo_verbose4(ErgoHeapSizing, 1618 "attempt heap expansion", 1619 ergo_format_reason("capacity lower than " 1620 "min desired capacity after Full GC") 1621 ergo_format_byte("capacity") 1622 ergo_format_byte("occupancy") 1623 ergo_format_byte_perc("min desired capacity"), 1624 capacity_after_gc, used_after_gc, 1625 minimum_desired_capacity, (double) MinHeapFreeRatio); 1626 expand(expand_bytes); 1627 1628 // No expansion, now see if we want to shrink 1629 } else if (capacity_after_gc > maximum_desired_capacity) { 1630 // Capacity too large, compute shrinking size 1631 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity; 1632 ergo_verbose4(ErgoHeapSizing, 1633 "attempt heap shrinking", 1634 ergo_format_reason("capacity higher than " 1635 "max desired capacity after Full GC") 1636 ergo_format_byte("capacity") 1637 ergo_format_byte("occupancy") 1638 ergo_format_byte_perc("max desired capacity"), 1639 capacity_after_gc, used_after_gc, 1640 maximum_desired_capacity, (double) MaxHeapFreeRatio); 1641 shrink(shrink_bytes); 1642 } 1643 } 1644 1645 1646 HeapWord* 1647 G1CollectedHeap::satisfy_failed_allocation(size_t word_size, 1648 bool* succeeded) { 1649 assert_at_safepoint(true /* should_be_vm_thread */); 1650 1651 *succeeded = true; 1652 // Let's attempt the allocation first. 1653 HeapWord* result = 1654 attempt_allocation_at_safepoint(word_size, 1655 false /* expect_null_mutator_alloc_region */); 1656 if (result != NULL) { 1657 assert(*succeeded, "sanity"); 1658 return result; 1659 } 1660 1661 // In a G1 heap, we're supposed to keep allocation from failing by 1662 // incremental pauses. Therefore, at least for now, we'll favor 1663 // expansion over collection. (This might change in the future if we can 1664 // do something smarter than full collection to satisfy a failed alloc.) 1665 result = expand_and_allocate(word_size); 1666 if (result != NULL) { 1667 assert(*succeeded, "sanity"); 1668 return result; 1669 } 1670 1671 // Expansion didn't work, we'll try to do a Full GC. 1672 bool gc_succeeded = do_collection(false, /* explicit_gc */ 1673 false, /* clear_all_soft_refs */ 1674 word_size); 1675 if (!gc_succeeded) { 1676 *succeeded = false; 1677 return NULL; 1678 } 1679 1680 // Retry the allocation 1681 result = attempt_allocation_at_safepoint(word_size, 1682 true /* expect_null_mutator_alloc_region */); 1683 if (result != NULL) { 1684 assert(*succeeded, "sanity"); 1685 return result; 1686 } 1687 1688 // Then, try a Full GC that will collect all soft references. 1689 gc_succeeded = do_collection(false, /* explicit_gc */ 1690 true, /* clear_all_soft_refs */ 1691 word_size); 1692 if (!gc_succeeded) { 1693 *succeeded = false; 1694 return NULL; 1695 } 1696 1697 // Retry the allocation once more 1698 result = attempt_allocation_at_safepoint(word_size, 1699 true /* expect_null_mutator_alloc_region */); 1700 if (result != NULL) { 1701 assert(*succeeded, "sanity"); 1702 return result; 1703 } 1704 1705 assert(!collector_policy()->should_clear_all_soft_refs(), 1706 "Flag should have been handled and cleared prior to this point"); 1707 1708 // What else? We might try synchronous finalization later. If the total 1709 // space available is large enough for the allocation, then a more 1710 // complete compaction phase than we've tried so far might be 1711 // appropriate. 1712 assert(*succeeded, "sanity"); 1713 return NULL; 1714 } 1715 1716 // Attempting to expand the heap sufficiently 1717 // to support an allocation of the given "word_size". If 1718 // successful, perform the allocation and return the address of the 1719 // allocated block, or else "NULL". 1720 1721 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) { 1722 assert_at_safepoint(true /* should_be_vm_thread */); 1723 1724 verify_region_sets_optional(); 1725 1726 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes); 1727 ergo_verbose1(ErgoHeapSizing, 1728 "attempt heap expansion", 1729 ergo_format_reason("allocation request failed") 1730 ergo_format_byte("allocation request"), 1731 word_size * HeapWordSize); 1732 if (expand(expand_bytes)) { 1733 _hrs.verify_optional(); 1734 verify_region_sets_optional(); 1735 return attempt_allocation_at_safepoint(word_size, 1736 false /* expect_null_mutator_alloc_region */); 1737 } 1738 return NULL; 1739 } 1740 1741 bool G1CollectedHeap::expand(size_t expand_bytes) { 1742 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); 1743 aligned_expand_bytes = align_size_up(aligned_expand_bytes, 1744 HeapRegion::GrainBytes); 1745 ergo_verbose2(ErgoHeapSizing, 1746 "expand the heap", 1747 ergo_format_byte("requested expansion amount") 1748 ergo_format_byte("attempted expansion amount"), 1749 expand_bytes, aligned_expand_bytes); 1750 1751 if (is_maximal_no_gc()) { 1752 ergo_verbose0(ErgoHeapSizing, 1753 "did not expand the heap", 1754 ergo_format_reason("heap already fully expanded")); 1755 return false; 1756 } 1757 1758 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes); 1759 assert(regions_to_expand > 0, "Must expand by at least one region"); 1760 1761 uint expanded_by = _hrs.expand_by(regions_to_expand); 1762 1763 if (expanded_by > 0) { 1764 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes; 1765 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition"); 1766 g1_policy()->record_new_heap_size(num_regions()); 1767 } else { 1768 ergo_verbose0(ErgoHeapSizing, 1769 "did not expand the heap", 1770 ergo_format_reason("heap expansion operation failed")); 1771 // The expansion of the virtual storage space was unsuccessful. 1772 // Let's see if it was because we ran out of swap. 1773 if (G1ExitOnExpansionFailure && 1774 _hrs.available() >= regions_to_expand) { 1775 // We had head room... 1776 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion"); 1777 } 1778 } 1779 return regions_to_expand > 0; 1780 } 1781 1782 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) { 1783 size_t aligned_shrink_bytes = 1784 ReservedSpace::page_align_size_down(shrink_bytes); 1785 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes, 1786 HeapRegion::GrainBytes); 1787 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes); 1788 1789 uint num_regions_removed = _hrs.shrink_by(num_regions_to_remove); 1790 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes; 1791 1792 ergo_verbose3(ErgoHeapSizing, 1793 "shrink the heap", 1794 ergo_format_byte("requested shrinking amount") 1795 ergo_format_byte("aligned shrinking amount") 1796 ergo_format_byte("attempted shrinking amount"), 1797 shrink_bytes, aligned_shrink_bytes, shrunk_bytes); 1798 if (num_regions_removed > 0) { 1799 g1_policy()->record_new_heap_size(num_regions()); 1800 } else { 1801 ergo_verbose0(ErgoHeapSizing, 1802 "did not shrink the heap", 1803 ergo_format_reason("heap shrinking operation failed")); 1804 } 1805 } 1806 1807 void G1CollectedHeap::shrink(size_t shrink_bytes) { 1808 verify_region_sets_optional(); 1809 1810 // We should only reach here at the end of a Full GC which means we 1811 // should not not be holding to any GC alloc regions. The method 1812 // below will make sure of that and do any remaining clean up. 1813 abandon_gc_alloc_regions(); 1814 1815 // Instead of tearing down / rebuilding the free lists here, we 1816 // could instead use the remove_all_pending() method on free_list to 1817 // remove only the ones that we need to remove. 1818 tear_down_region_sets(true /* free_list_only */); 1819 shrink_helper(shrink_bytes); 1820 rebuild_region_sets(true /* free_list_only */); 1821 1822 _hrs.verify_optional(); 1823 verify_region_sets_optional(); 1824 } 1825 1826 // Public methods. 1827 1828 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away 1829 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list 1830 #endif // _MSC_VER 1831 1832 1833 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) : 1834 SharedHeap(policy_), 1835 _g1_policy(policy_), 1836 _dirty_card_queue_set(false), 1837 _into_cset_dirty_card_queue_set(false), 1838 _is_alive_closure_cm(this), 1839 _is_alive_closure_stw(this), 1840 _ref_processor_cm(NULL), 1841 _ref_processor_stw(NULL), 1842 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)), 1843 _bot_shared(NULL), 1844 _evac_failure_scan_stack(NULL), 1845 _mark_in_progress(false), 1846 _cg1r(NULL), _summary_bytes_used(0), 1847 _g1mm(NULL), 1848 _refine_cte_cl(NULL), 1849 _full_collection(false), 1850 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()), 1851 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()), 1852 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()), 1853 _humongous_is_live(), 1854 _has_humongous_reclaim_candidates(false), 1855 _free_regions_coming(false), 1856 _young_list(new YoungList(this)), 1857 _gc_time_stamp(0), 1858 _retained_old_gc_alloc_region(NULL), 1859 _survivor_plab_stats(YoungPLABSize, PLABWeight), 1860 _old_plab_stats(OldPLABSize, PLABWeight), 1861 _expand_heap_after_alloc_failure(true), 1862 _surviving_young_words(NULL), 1863 _old_marking_cycles_started(0), 1864 _old_marking_cycles_completed(0), 1865 _concurrent_cycle_started(false), 1866 _in_cset_fast_test(), 1867 _dirty_cards_region_list(NULL), 1868 _worker_cset_start_region(NULL), 1869 _worker_cset_start_region_time_stamp(NULL), 1870 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()), 1871 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()), 1872 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()), 1873 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) { 1874 1875 _g1h = this; 1876 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) { 1877 vm_exit_during_initialization("Failed necessary allocation."); 1878 } 1879 1880 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2; 1881 1882 int n_queues = MAX2((int)ParallelGCThreads, 1); 1883 _task_queues = new RefToScanQueueSet(n_queues); 1884 1885 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets(); 1886 assert(n_rem_sets > 0, "Invariant."); 1887 1888 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC); 1889 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(unsigned int, n_queues, mtGC); 1890 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC); 1891 1892 for (int i = 0; i < n_queues; i++) { 1893 RefToScanQueue* q = new RefToScanQueue(); 1894 q->initialize(); 1895 _task_queues->register_queue(i, q); 1896 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo(); 1897 } 1898 clear_cset_start_regions(); 1899 1900 // Initialize the G1EvacuationFailureALot counters and flags. 1901 NOT_PRODUCT(reset_evacuation_should_fail();) 1902 1903 guarantee(_task_queues != NULL, "task_queues allocation failure."); 1904 } 1905 1906 jint G1CollectedHeap::initialize() { 1907 CollectedHeap::pre_initialize(); 1908 os::enable_vtime(); 1909 1910 G1Log::init(); 1911 1912 // Necessary to satisfy locking discipline assertions. 1913 1914 MutexLocker x(Heap_lock); 1915 1916 // We have to initialize the printer before committing the heap, as 1917 // it will be used then. 1918 _hr_printer.set_active(G1PrintHeapRegions); 1919 1920 // While there are no constraints in the GC code that HeapWordSize 1921 // be any particular value, there are multiple other areas in the 1922 // system which believe this to be true (e.g. oop->object_size in some 1923 // cases incorrectly returns the size in wordSize units rather than 1924 // HeapWordSize). 1925 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 1926 1927 size_t init_byte_size = collector_policy()->initial_heap_byte_size(); 1928 size_t max_byte_size = collector_policy()->max_heap_byte_size(); 1929 size_t heap_alignment = collector_policy()->heap_alignment(); 1930 1931 // Ensure that the sizes are properly aligned. 1932 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1933 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1934 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap"); 1935 1936 _refine_cte_cl = new RefineCardTableEntryClosure(); 1937 1938 _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl); 1939 1940 // Reserve the maximum. 1941 1942 // When compressed oops are enabled, the preferred heap base 1943 // is calculated by subtracting the requested size from the 1944 // 32Gb boundary and using the result as the base address for 1945 // heap reservation. If the requested size is not aligned to 1946 // HeapRegion::GrainBytes (i.e. the alignment that is passed 1947 // into the ReservedHeapSpace constructor) then the actual 1948 // base of the reserved heap may end up differing from the 1949 // address that was requested (i.e. the preferred heap base). 1950 // If this happens then we could end up using a non-optimal 1951 // compressed oops mode. 1952 1953 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size, 1954 heap_alignment); 1955 1956 // It is important to do this in a way such that concurrent readers can't 1957 // temporarily think something is in the heap. (I've actually seen this 1958 // happen in asserts: DLD.) 1959 _reserved.set_word_size(0); 1960 _reserved.set_start((HeapWord*)heap_rs.base()); 1961 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size())); 1962 1963 // Create the gen rem set (and barrier set) for the entire reserved region. 1964 _rem_set = collector_policy()->create_rem_set(_reserved, 2); 1965 set_barrier_set(rem_set()->bs()); 1966 if (!barrier_set()->is_a(BarrierSet::G1SATBCTLogging)) { 1967 vm_exit_during_initialization("G1 requires a G1SATBLoggingCardTableModRefBS"); 1968 return JNI_ENOMEM; 1969 } 1970 1971 // Also create a G1 rem set. 1972 _g1_rem_set = new G1RemSet(this, g1_barrier_set()); 1973 1974 // Carve out the G1 part of the heap. 1975 1976 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size); 1977 G1RegionToSpaceMapper* heap_storage = 1978 G1RegionToSpaceMapper::create_mapper(g1_rs, 1979 UseLargePages ? os::large_page_size() : os::vm_page_size(), 1980 HeapRegion::GrainBytes, 1981 1, 1982 mtJavaHeap); 1983 heap_storage->set_mapping_changed_listener(&_listener); 1984 1985 // Reserve space for the block offset table. We do not support automatic uncommit 1986 // for the card table at this time. BOT only. 1987 ReservedSpace bot_rs(G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize)); 1988 G1RegionToSpaceMapper* bot_storage = 1989 G1RegionToSpaceMapper::create_mapper(bot_rs, 1990 os::vm_page_size(), 1991 HeapRegion::GrainBytes, 1992 G1BlockOffsetSharedArray::N_bytes, 1993 mtGC); 1994 1995 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize)); 1996 G1RegionToSpaceMapper* cardtable_storage = 1997 G1RegionToSpaceMapper::create_mapper(cardtable_rs, 1998 os::vm_page_size(), 1999 HeapRegion::GrainBytes, 2000 G1BlockOffsetSharedArray::N_bytes, 2001 mtGC); 2002 2003 // Reserve space for the card counts table. 2004 ReservedSpace card_counts_rs(G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize)); 2005 G1RegionToSpaceMapper* card_counts_storage = 2006 G1RegionToSpaceMapper::create_mapper(card_counts_rs, 2007 os::vm_page_size(), 2008 HeapRegion::GrainBytes, 2009 G1BlockOffsetSharedArray::N_bytes, 2010 mtGC); 2011 2012 // Reserve space for prev and next bitmap. 2013 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size()); 2014 2015 ReservedSpace prev_bitmap_rs(ReservedSpace::allocation_align_size_up(bitmap_size)); 2016 G1RegionToSpaceMapper* prev_bitmap_storage = 2017 G1RegionToSpaceMapper::create_mapper(prev_bitmap_rs, 2018 os::vm_page_size(), 2019 HeapRegion::GrainBytes, 2020 CMBitMap::mark_distance(), 2021 mtGC); 2022 2023 ReservedSpace next_bitmap_rs(ReservedSpace::allocation_align_size_up(bitmap_size)); 2024 G1RegionToSpaceMapper* next_bitmap_storage = 2025 G1RegionToSpaceMapper::create_mapper(next_bitmap_rs, 2026 os::vm_page_size(), 2027 HeapRegion::GrainBytes, 2028 CMBitMap::mark_distance(), 2029 mtGC); 2030 2031 _hrs.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage); 2032 g1_barrier_set()->initialize(cardtable_storage); 2033 // Do later initialization work for concurrent refinement. 2034 _cg1r->init(card_counts_storage); 2035 2036 // 6843694 - ensure that the maximum region index can fit 2037 // in the remembered set structures. 2038 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; 2039 guarantee((max_regions() - 1) <= max_region_idx, "too many regions"); 2040 2041 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; 2042 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); 2043 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region, 2044 "too many cards per region"); 2045 2046 FreeRegionList::set_unrealistically_long_length(max_regions() + 1); 2047 2048 _bot_shared = new G1BlockOffsetSharedArray(_reserved, bot_storage); 2049 2050 _g1h = this; 2051 2052 _in_cset_fast_test.initialize(_hrs.reserved().start(), _hrs.reserved().end(), HeapRegion::GrainBytes); 2053 _humongous_is_live.initialize(_hrs.reserved().start(), _hrs.reserved().end(), HeapRegion::GrainBytes); 2054 2055 // Create the ConcurrentMark data structure and thread. 2056 // (Must do this late, so that "max_regions" is defined.) 2057 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage); 2058 if (_cm == NULL || !_cm->completed_initialization()) { 2059 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark"); 2060 return JNI_ENOMEM; 2061 } 2062 _cmThread = _cm->cmThread(); 2063 2064 // Initialize the from_card cache structure of HeapRegionRemSet. 2065 HeapRegionRemSet::init_heap(max_regions()); 2066 2067 // Now expand into the initial heap size. 2068 if (!expand(init_byte_size)) { 2069 vm_shutdown_during_initialization("Failed to allocate initial heap."); 2070 return JNI_ENOMEM; 2071 } 2072 2073 // Perform any initialization actions delegated to the policy. 2074 g1_policy()->init(); 2075 2076 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon, 2077 SATB_Q_FL_lock, 2078 G1SATBProcessCompletedThreshold, 2079 Shared_SATB_Q_lock); 2080 2081 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl, 2082 DirtyCardQ_CBL_mon, 2083 DirtyCardQ_FL_lock, 2084 concurrent_g1_refine()->yellow_zone(), 2085 concurrent_g1_refine()->red_zone(), 2086 Shared_DirtyCardQ_lock); 2087 2088 if (G1DeferredRSUpdate) { 2089 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code 2090 DirtyCardQ_CBL_mon, 2091 DirtyCardQ_FL_lock, 2092 -1, // never trigger processing 2093 -1, // no limit on length 2094 Shared_DirtyCardQ_lock, 2095 &JavaThread::dirty_card_queue_set()); 2096 } 2097 2098 // Initialize the card queue set used to hold cards containing 2099 // references into the collection set. 2100 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code 2101 DirtyCardQ_CBL_mon, 2102 DirtyCardQ_FL_lock, 2103 -1, // never trigger processing 2104 -1, // no limit on length 2105 Shared_DirtyCardQ_lock, 2106 &JavaThread::dirty_card_queue_set()); 2107 2108 // In case we're keeping closure specialization stats, initialize those 2109 // counts and that mechanism. 2110 SpecializationStats::clear(); 2111 2112 // Here we allocate the dummy HeapRegion that is required by the 2113 // G1AllocRegion class. 2114 HeapRegion* dummy_region = _hrs.get_dummy_region(); 2115 2116 // We'll re-use the same region whether the alloc region will 2117 // require BOT updates or not and, if it doesn't, then a non-young 2118 // region will complain that it cannot support allocations without 2119 // BOT updates. So we'll tag the dummy region as young to avoid that. 2120 dummy_region->set_young(); 2121 // Make sure it's full. 2122 dummy_region->set_top(dummy_region->end()); 2123 G1AllocRegion::setup(this, dummy_region); 2124 2125 init_mutator_alloc_region(); 2126 2127 // Do create of the monitoring and management support so that 2128 // values in the heap have been properly initialized. 2129 _g1mm = new G1MonitoringSupport(this); 2130 2131 G1StringDedup::initialize(); 2132 2133 return JNI_OK; 2134 } 2135 2136 void G1CollectedHeap::stop() { 2137 // Stop all concurrent threads. We do this to make sure these threads 2138 // do not continue to execute and access resources (e.g. gclog_or_tty) 2139 // that are destroyed during shutdown. 2140 _cg1r->stop(); 2141 _cmThread->stop(); 2142 if (G1StringDedup::is_enabled()) { 2143 G1StringDedup::stop(); 2144 } 2145 } 2146 2147 void G1CollectedHeap::clear_humongous_is_live_table() { 2148 guarantee(G1ReclaimDeadHumongousObjectsAtYoungGC, "Should only be called if true"); 2149 _humongous_is_live.clear(); 2150 } 2151 2152 size_t G1CollectedHeap::conservative_max_heap_alignment() { 2153 return HeapRegion::max_region_size(); 2154 } 2155 2156 void G1CollectedHeap::ref_processing_init() { 2157 // Reference processing in G1 currently works as follows: 2158 // 2159 // * There are two reference processor instances. One is 2160 // used to record and process discovered references 2161 // during concurrent marking; the other is used to 2162 // record and process references during STW pauses 2163 // (both full and incremental). 2164 // * Both ref processors need to 'span' the entire heap as 2165 // the regions in the collection set may be dotted around. 2166 // 2167 // * For the concurrent marking ref processor: 2168 // * Reference discovery is enabled at initial marking. 2169 // * Reference discovery is disabled and the discovered 2170 // references processed etc during remarking. 2171 // * Reference discovery is MT (see below). 2172 // * Reference discovery requires a barrier (see below). 2173 // * Reference processing may or may not be MT 2174 // (depending on the value of ParallelRefProcEnabled 2175 // and ParallelGCThreads). 2176 // * A full GC disables reference discovery by the CM 2177 // ref processor and abandons any entries on it's 2178 // discovered lists. 2179 // 2180 // * For the STW processor: 2181 // * Non MT discovery is enabled at the start of a full GC. 2182 // * Processing and enqueueing during a full GC is non-MT. 2183 // * During a full GC, references are processed after marking. 2184 // 2185 // * Discovery (may or may not be MT) is enabled at the start 2186 // of an incremental evacuation pause. 2187 // * References are processed near the end of a STW evacuation pause. 2188 // * For both types of GC: 2189 // * Discovery is atomic - i.e. not concurrent. 2190 // * Reference discovery will not need a barrier. 2191 2192 SharedHeap::ref_processing_init(); 2193 MemRegion mr = reserved_region(); 2194 2195 // Concurrent Mark ref processor 2196 _ref_processor_cm = 2197 new ReferenceProcessor(mr, // span 2198 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2199 // mt processing 2200 (int) ParallelGCThreads, 2201 // degree of mt processing 2202 (ParallelGCThreads > 1) || (ConcGCThreads > 1), 2203 // mt discovery 2204 (int) MAX2(ParallelGCThreads, ConcGCThreads), 2205 // degree of mt discovery 2206 false, 2207 // Reference discovery is not atomic 2208 &_is_alive_closure_cm); 2209 // is alive closure 2210 // (for efficiency/performance) 2211 2212 // STW ref processor 2213 _ref_processor_stw = 2214 new ReferenceProcessor(mr, // span 2215 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2216 // mt processing 2217 MAX2((int)ParallelGCThreads, 1), 2218 // degree of mt processing 2219 (ParallelGCThreads > 1), 2220 // mt discovery 2221 MAX2((int)ParallelGCThreads, 1), 2222 // degree of mt discovery 2223 true, 2224 // Reference discovery is atomic 2225 &_is_alive_closure_stw); 2226 // is alive closure 2227 // (for efficiency/performance) 2228 } 2229 2230 size_t G1CollectedHeap::capacity() const { 2231 return _hrs.length() * HeapRegion::GrainBytes; 2232 } 2233 2234 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) { 2235 assert(!hr->continuesHumongous(), "pre-condition"); 2236 hr->reset_gc_time_stamp(); 2237 if (hr->startsHumongous()) { 2238 uint first_index = hr->hrs_index() + 1; 2239 uint last_index = hr->last_hc_index(); 2240 for (uint i = first_index; i < last_index; i += 1) { 2241 HeapRegion* chr = region_at(i); 2242 assert(chr->continuesHumongous(), "sanity"); 2243 chr->reset_gc_time_stamp(); 2244 } 2245 } 2246 } 2247 2248 #ifndef PRODUCT 2249 class CheckGCTimeStampsHRClosure : public HeapRegionClosure { 2250 private: 2251 unsigned _gc_time_stamp; 2252 bool _failures; 2253 2254 public: 2255 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) : 2256 _gc_time_stamp(gc_time_stamp), _failures(false) { } 2257 2258 virtual bool doHeapRegion(HeapRegion* hr) { 2259 unsigned region_gc_time_stamp = hr->get_gc_time_stamp(); 2260 if (_gc_time_stamp != region_gc_time_stamp) { 2261 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, " 2262 "expected %d", HR_FORMAT_PARAMS(hr), 2263 region_gc_time_stamp, _gc_time_stamp); 2264 _failures = true; 2265 } 2266 return false; 2267 } 2268 2269 bool failures() { return _failures; } 2270 }; 2271 2272 void G1CollectedHeap::check_gc_time_stamps() { 2273 CheckGCTimeStampsHRClosure cl(_gc_time_stamp); 2274 heap_region_iterate(&cl); 2275 guarantee(!cl.failures(), "all GC time stamps should have been reset"); 2276 } 2277 #endif // PRODUCT 2278 2279 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, 2280 DirtyCardQueue* into_cset_dcq, 2281 bool concurrent, 2282 uint worker_i) { 2283 // Clean cards in the hot card cache 2284 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 2285 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq); 2286 2287 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 2288 int n_completed_buffers = 0; 2289 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) { 2290 n_completed_buffers++; 2291 } 2292 g1_policy()->phase_times()->record_update_rs_processed_buffers(worker_i, n_completed_buffers); 2293 dcqs.clear_n_completed_buffers(); 2294 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!"); 2295 } 2296 2297 2298 // Computes the sum of the storage used by the various regions. 2299 2300 size_t G1CollectedHeap::used() const { 2301 assert(Heap_lock->owner() != NULL, 2302 "Should be owned on this thread's behalf."); 2303 size_t result = _summary_bytes_used; 2304 // Read only once in case it is set to NULL concurrently 2305 HeapRegion* hr = _mutator_alloc_region.get(); 2306 if (hr != NULL) 2307 result += hr->used(); 2308 return result; 2309 } 2310 2311 size_t G1CollectedHeap::used_unlocked() const { 2312 size_t result = _summary_bytes_used; 2313 return result; 2314 } 2315 2316 class SumUsedClosure: public HeapRegionClosure { 2317 size_t _used; 2318 public: 2319 SumUsedClosure() : _used(0) {} 2320 bool doHeapRegion(HeapRegion* r) { 2321 if (!r->continuesHumongous()) { 2322 _used += r->used(); 2323 } 2324 return false; 2325 } 2326 size_t result() { return _used; } 2327 }; 2328 2329 size_t G1CollectedHeap::recalculate_used() const { 2330 double recalculate_used_start = os::elapsedTime(); 2331 2332 SumUsedClosure blk; 2333 heap_region_iterate(&blk); 2334 2335 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0); 2336 return blk.result(); 2337 } 2338 2339 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 2340 switch (cause) { 2341 case GCCause::_gc_locker: return GCLockerInvokesConcurrent; 2342 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent; 2343 case GCCause::_g1_humongous_allocation: return true; 2344 default: return false; 2345 } 2346 } 2347 2348 #ifndef PRODUCT 2349 void G1CollectedHeap::allocate_dummy_regions() { 2350 // Let's fill up most of the region 2351 size_t word_size = HeapRegion::GrainWords - 1024; 2352 // And as a result the region we'll allocate will be humongous. 2353 guarantee(isHumongous(word_size), "sanity"); 2354 2355 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) { 2356 // Let's use the existing mechanism for the allocation 2357 HeapWord* dummy_obj = humongous_obj_allocate(word_size); 2358 if (dummy_obj != NULL) { 2359 MemRegion mr(dummy_obj, word_size); 2360 CollectedHeap::fill_with_object(mr); 2361 } else { 2362 // If we can't allocate once, we probably cannot allocate 2363 // again. Let's get out of the loop. 2364 break; 2365 } 2366 } 2367 } 2368 #endif // !PRODUCT 2369 2370 void G1CollectedHeap::increment_old_marking_cycles_started() { 2371 assert(_old_marking_cycles_started == _old_marking_cycles_completed || 2372 _old_marking_cycles_started == _old_marking_cycles_completed + 1, 2373 err_msg("Wrong marking cycle count (started: %d, completed: %d)", 2374 _old_marking_cycles_started, _old_marking_cycles_completed)); 2375 2376 _old_marking_cycles_started++; 2377 } 2378 2379 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) { 2380 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 2381 2382 // We assume that if concurrent == true, then the caller is a 2383 // concurrent thread that was joined the Suspendible Thread 2384 // Set. If there's ever a cheap way to check this, we should add an 2385 // assert here. 2386 2387 // Given that this method is called at the end of a Full GC or of a 2388 // concurrent cycle, and those can be nested (i.e., a Full GC can 2389 // interrupt a concurrent cycle), the number of full collections 2390 // completed should be either one (in the case where there was no 2391 // nesting) or two (when a Full GC interrupted a concurrent cycle) 2392 // behind the number of full collections started. 2393 2394 // This is the case for the inner caller, i.e. a Full GC. 2395 assert(concurrent || 2396 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || 2397 (_old_marking_cycles_started == _old_marking_cycles_completed + 2), 2398 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u " 2399 "is inconsistent with _old_marking_cycles_completed = %u", 2400 _old_marking_cycles_started, _old_marking_cycles_completed)); 2401 2402 // This is the case for the outer caller, i.e. the concurrent cycle. 2403 assert(!concurrent || 2404 (_old_marking_cycles_started == _old_marking_cycles_completed + 1), 2405 err_msg("for outer caller (concurrent cycle): " 2406 "_old_marking_cycles_started = %u " 2407 "is inconsistent with _old_marking_cycles_completed = %u", 2408 _old_marking_cycles_started, _old_marking_cycles_completed)); 2409 2410 _old_marking_cycles_completed += 1; 2411 2412 // We need to clear the "in_progress" flag in the CM thread before 2413 // we wake up any waiters (especially when ExplicitInvokesConcurrent 2414 // is set) so that if a waiter requests another System.gc() it doesn't 2415 // incorrectly see that a marking cycle is still in progress. 2416 if (concurrent) { 2417 _cmThread->clear_in_progress(); 2418 } 2419 2420 // This notify_all() will ensure that a thread that called 2421 // System.gc() with (with ExplicitGCInvokesConcurrent set or not) 2422 // and it's waiting for a full GC to finish will be woken up. It is 2423 // waiting in VM_G1IncCollectionPause::doit_epilogue(). 2424 FullGCCount_lock->notify_all(); 2425 } 2426 2427 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) { 2428 _concurrent_cycle_started = true; 2429 _gc_timer_cm->register_gc_start(start_time); 2430 2431 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start()); 2432 trace_heap_before_gc(_gc_tracer_cm); 2433 } 2434 2435 void G1CollectedHeap::register_concurrent_cycle_end() { 2436 if (_concurrent_cycle_started) { 2437 if (_cm->has_aborted()) { 2438 _gc_tracer_cm->report_concurrent_mode_failure(); 2439 } 2440 2441 _gc_timer_cm->register_gc_end(); 2442 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions()); 2443 2444 _concurrent_cycle_started = false; 2445 } 2446 } 2447 2448 void G1CollectedHeap::trace_heap_after_concurrent_cycle() { 2449 if (_concurrent_cycle_started) { 2450 trace_heap_after_gc(_gc_tracer_cm); 2451 } 2452 } 2453 2454 G1YCType G1CollectedHeap::yc_type() { 2455 bool is_young = g1_policy()->gcs_are_young(); 2456 bool is_initial_mark = g1_policy()->during_initial_mark_pause(); 2457 bool is_during_mark = mark_in_progress(); 2458 2459 if (is_initial_mark) { 2460 return InitialMark; 2461 } else if (is_during_mark) { 2462 return DuringMark; 2463 } else if (is_young) { 2464 return Normal; 2465 } else { 2466 return Mixed; 2467 } 2468 } 2469 2470 void G1CollectedHeap::collect(GCCause::Cause cause) { 2471 assert_heap_not_locked(); 2472 2473 unsigned int gc_count_before; 2474 unsigned int old_marking_count_before; 2475 bool retry_gc; 2476 2477 do { 2478 retry_gc = false; 2479 2480 { 2481 MutexLocker ml(Heap_lock); 2482 2483 // Read the GC count while holding the Heap_lock 2484 gc_count_before = total_collections(); 2485 old_marking_count_before = _old_marking_cycles_started; 2486 } 2487 2488 if (should_do_concurrent_full_gc(cause)) { 2489 // Schedule an initial-mark evacuation pause that will start a 2490 // concurrent cycle. We're setting word_size to 0 which means that 2491 // we are not requesting a post-GC allocation. 2492 VM_G1IncCollectionPause op(gc_count_before, 2493 0, /* word_size */ 2494 true, /* should_initiate_conc_mark */ 2495 g1_policy()->max_pause_time_ms(), 2496 cause); 2497 2498 VMThread::execute(&op); 2499 if (!op.pause_succeeded()) { 2500 if (old_marking_count_before == _old_marking_cycles_started) { 2501 retry_gc = op.should_retry_gc(); 2502 } else { 2503 // A Full GC happened while we were trying to schedule the 2504 // initial-mark GC. No point in starting a new cycle given 2505 // that the whole heap was collected anyway. 2506 } 2507 2508 if (retry_gc) { 2509 if (GC_locker::is_active_and_needs_gc()) { 2510 GC_locker::stall_until_clear(); 2511 } 2512 } 2513 } 2514 } else { 2515 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc 2516 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { 2517 2518 // Schedule a standard evacuation pause. We're setting word_size 2519 // to 0 which means that we are not requesting a post-GC allocation. 2520 VM_G1IncCollectionPause op(gc_count_before, 2521 0, /* word_size */ 2522 false, /* should_initiate_conc_mark */ 2523 g1_policy()->max_pause_time_ms(), 2524 cause); 2525 VMThread::execute(&op); 2526 } else { 2527 // Schedule a Full GC. 2528 VM_G1CollectFull op(gc_count_before, old_marking_count_before, cause); 2529 VMThread::execute(&op); 2530 } 2531 } 2532 } while (retry_gc); 2533 } 2534 2535 bool G1CollectedHeap::is_in(const void* p) const { 2536 if (_hrs.reserved().contains(p)) { 2537 // Given that we know that p is in the reserved space, 2538 // heap_region_containing_raw() should successfully 2539 // return the containing region. 2540 HeapRegion* hr = heap_region_containing_raw(p); 2541 return hr->is_in(p); 2542 } else { 2543 return false; 2544 } 2545 } 2546 2547 #ifdef ASSERT 2548 bool G1CollectedHeap::is_in_exact(const void* p) const { 2549 bool contains = reserved_region().contains(p); 2550 bool available = _hrs.is_available(addr_to_region((HeapWord*)p)); 2551 if (contains && available) { 2552 return true; 2553 } else { 2554 return false; 2555 } 2556 } 2557 #endif 2558 2559 // Iteration functions. 2560 2561 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion. 2562 2563 class IterateOopClosureRegionClosure: public HeapRegionClosure { 2564 ExtendedOopClosure* _cl; 2565 public: 2566 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {} 2567 bool doHeapRegion(HeapRegion* r) { 2568 if (!r->continuesHumongous()) { 2569 r->oop_iterate(_cl); 2570 } 2571 return false; 2572 } 2573 }; 2574 2575 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) { 2576 IterateOopClosureRegionClosure blk(cl); 2577 heap_region_iterate(&blk); 2578 } 2579 2580 // Iterates an ObjectClosure over all objects within a HeapRegion. 2581 2582 class IterateObjectClosureRegionClosure: public HeapRegionClosure { 2583 ObjectClosure* _cl; 2584 public: 2585 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} 2586 bool doHeapRegion(HeapRegion* r) { 2587 if (! r->continuesHumongous()) { 2588 r->object_iterate(_cl); 2589 } 2590 return false; 2591 } 2592 }; 2593 2594 void G1CollectedHeap::object_iterate(ObjectClosure* cl) { 2595 IterateObjectClosureRegionClosure blk(cl); 2596 heap_region_iterate(&blk); 2597 } 2598 2599 // Calls a SpaceClosure on a HeapRegion. 2600 2601 class SpaceClosureRegionClosure: public HeapRegionClosure { 2602 SpaceClosure* _cl; 2603 public: 2604 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {} 2605 bool doHeapRegion(HeapRegion* r) { 2606 _cl->do_space(r); 2607 return false; 2608 } 2609 }; 2610 2611 void G1CollectedHeap::space_iterate(SpaceClosure* cl) { 2612 SpaceClosureRegionClosure blk(cl); 2613 heap_region_iterate(&blk); 2614 } 2615 2616 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { 2617 _hrs.iterate(cl); 2618 } 2619 2620 void 2621 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl, 2622 uint worker_id, 2623 uint num_workers, 2624 jint claim_value) const { 2625 _hrs.par_iterate(cl, worker_id, num_workers, claim_value); 2626 } 2627 2628 class ResetClaimValuesClosure: public HeapRegionClosure { 2629 public: 2630 bool doHeapRegion(HeapRegion* r) { 2631 r->set_claim_value(HeapRegion::InitialClaimValue); 2632 return false; 2633 } 2634 }; 2635 2636 void G1CollectedHeap::reset_heap_region_claim_values() { 2637 ResetClaimValuesClosure blk; 2638 heap_region_iterate(&blk); 2639 } 2640 2641 void G1CollectedHeap::reset_cset_heap_region_claim_values() { 2642 ResetClaimValuesClosure blk; 2643 collection_set_iterate(&blk); 2644 } 2645 2646 #ifdef ASSERT 2647 // This checks whether all regions in the heap have the correct claim 2648 // value. I also piggy-backed on this a check to ensure that the 2649 // humongous_start_region() information on "continues humongous" 2650 // regions is correct. 2651 2652 class CheckClaimValuesClosure : public HeapRegionClosure { 2653 private: 2654 jint _claim_value; 2655 uint _failures; 2656 HeapRegion* _sh_region; 2657 2658 public: 2659 CheckClaimValuesClosure(jint claim_value) : 2660 _claim_value(claim_value), _failures(0), _sh_region(NULL) { } 2661 bool doHeapRegion(HeapRegion* r) { 2662 if (r->claim_value() != _claim_value) { 2663 gclog_or_tty->print_cr("Region " HR_FORMAT ", " 2664 "claim value = %d, should be %d", 2665 HR_FORMAT_PARAMS(r), 2666 r->claim_value(), _claim_value); 2667 ++_failures; 2668 } 2669 if (!r->isHumongous()) { 2670 _sh_region = NULL; 2671 } else if (r->startsHumongous()) { 2672 _sh_region = r; 2673 } else if (r->continuesHumongous()) { 2674 if (r->humongous_start_region() != _sh_region) { 2675 gclog_or_tty->print_cr("Region " HR_FORMAT ", " 2676 "HS = "PTR_FORMAT", should be "PTR_FORMAT, 2677 HR_FORMAT_PARAMS(r), 2678 r->humongous_start_region(), 2679 _sh_region); 2680 ++_failures; 2681 } 2682 } 2683 return false; 2684 } 2685 uint failures() { return _failures; } 2686 }; 2687 2688 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) { 2689 CheckClaimValuesClosure cl(claim_value); 2690 heap_region_iterate(&cl); 2691 return cl.failures() == 0; 2692 } 2693 2694 class CheckClaimValuesInCSetHRClosure: public HeapRegionClosure { 2695 private: 2696 jint _claim_value; 2697 uint _failures; 2698 2699 public: 2700 CheckClaimValuesInCSetHRClosure(jint claim_value) : 2701 _claim_value(claim_value), _failures(0) { } 2702 2703 uint failures() { return _failures; } 2704 2705 bool doHeapRegion(HeapRegion* hr) { 2706 assert(hr->in_collection_set(), "how?"); 2707 assert(!hr->isHumongous(), "H-region in CSet"); 2708 if (hr->claim_value() != _claim_value) { 2709 gclog_or_tty->print_cr("CSet Region " HR_FORMAT ", " 2710 "claim value = %d, should be %d", 2711 HR_FORMAT_PARAMS(hr), 2712 hr->claim_value(), _claim_value); 2713 _failures += 1; 2714 } 2715 return false; 2716 } 2717 }; 2718 2719 bool G1CollectedHeap::check_cset_heap_region_claim_values(jint claim_value) { 2720 CheckClaimValuesInCSetHRClosure cl(claim_value); 2721 collection_set_iterate(&cl); 2722 return cl.failures() == 0; 2723 } 2724 #endif // ASSERT 2725 2726 // Clear the cached CSet starting regions and (more importantly) 2727 // the time stamps. Called when we reset the GC time stamp. 2728 void G1CollectedHeap::clear_cset_start_regions() { 2729 assert(_worker_cset_start_region != NULL, "sanity"); 2730 assert(_worker_cset_start_region_time_stamp != NULL, "sanity"); 2731 2732 int n_queues = MAX2((int)ParallelGCThreads, 1); 2733 for (int i = 0; i < n_queues; i++) { 2734 _worker_cset_start_region[i] = NULL; 2735 _worker_cset_start_region_time_stamp[i] = 0; 2736 } 2737 } 2738 2739 // Given the id of a worker, obtain or calculate a suitable 2740 // starting region for iterating over the current collection set. 2741 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) { 2742 assert(get_gc_time_stamp() > 0, "should have been updated by now"); 2743 2744 HeapRegion* result = NULL; 2745 unsigned gc_time_stamp = get_gc_time_stamp(); 2746 2747 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) { 2748 // Cached starting region for current worker was set 2749 // during the current pause - so it's valid. 2750 // Note: the cached starting heap region may be NULL 2751 // (when the collection set is empty). 2752 result = _worker_cset_start_region[worker_i]; 2753 assert(result == NULL || result->in_collection_set(), "sanity"); 2754 return result; 2755 } 2756 2757 // The cached entry was not valid so let's calculate 2758 // a suitable starting heap region for this worker. 2759 2760 // We want the parallel threads to start their collection 2761 // set iteration at different collection set regions to 2762 // avoid contention. 2763 // If we have: 2764 // n collection set regions 2765 // p threads 2766 // Then thread t will start at region floor ((t * n) / p) 2767 2768 result = g1_policy()->collection_set(); 2769 if (G1CollectedHeap::use_parallel_gc_threads()) { 2770 uint cs_size = g1_policy()->cset_region_length(); 2771 uint active_workers = workers()->active_workers(); 2772 assert(UseDynamicNumberOfGCThreads || 2773 active_workers == workers()->total_workers(), 2774 "Unless dynamic should use total workers"); 2775 2776 uint end_ind = (cs_size * worker_i) / active_workers; 2777 uint start_ind = 0; 2778 2779 if (worker_i > 0 && 2780 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) { 2781 // Previous workers starting region is valid 2782 // so let's iterate from there 2783 start_ind = (cs_size * (worker_i - 1)) / active_workers; 2784 result = _worker_cset_start_region[worker_i - 1]; 2785 } 2786 2787 for (uint i = start_ind; i < end_ind; i++) { 2788 result = result->next_in_collection_set(); 2789 } 2790 } 2791 2792 // Note: the calculated starting heap region may be NULL 2793 // (when the collection set is empty). 2794 assert(result == NULL || result->in_collection_set(), "sanity"); 2795 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp, 2796 "should be updated only once per pause"); 2797 _worker_cset_start_region[worker_i] = result; 2798 OrderAccess::storestore(); 2799 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp; 2800 return result; 2801 } 2802 2803 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) { 2804 HeapRegion* r = g1_policy()->collection_set(); 2805 while (r != NULL) { 2806 HeapRegion* next = r->next_in_collection_set(); 2807 if (cl->doHeapRegion(r)) { 2808 cl->incomplete(); 2809 return; 2810 } 2811 r = next; 2812 } 2813 } 2814 2815 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r, 2816 HeapRegionClosure *cl) { 2817 if (r == NULL) { 2818 // The CSet is empty so there's nothing to do. 2819 return; 2820 } 2821 2822 assert(r->in_collection_set(), 2823 "Start region must be a member of the collection set."); 2824 HeapRegion* cur = r; 2825 while (cur != NULL) { 2826 HeapRegion* next = cur->next_in_collection_set(); 2827 if (cl->doHeapRegion(cur) && false) { 2828 cl->incomplete(); 2829 return; 2830 } 2831 cur = next; 2832 } 2833 cur = g1_policy()->collection_set(); 2834 while (cur != r) { 2835 HeapRegion* next = cur->next_in_collection_set(); 2836 if (cl->doHeapRegion(cur) && false) { 2837 cl->incomplete(); 2838 return; 2839 } 2840 cur = next; 2841 } 2842 } 2843 2844 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const { 2845 HeapRegion* result = _hrs.next_region_in_heap(from); 2846 while (result != NULL && result->isHumongous()) { 2847 result = _hrs.next_region_in_heap(result); 2848 } 2849 return result; 2850 } 2851 2852 Space* G1CollectedHeap::space_containing(const void* addr) const { 2853 return heap_region_containing(addr); 2854 } 2855 2856 HeapWord* G1CollectedHeap::block_start(const void* addr) const { 2857 Space* sp = space_containing(addr); 2858 return sp->block_start(addr); 2859 } 2860 2861 size_t G1CollectedHeap::block_size(const HeapWord* addr) const { 2862 Space* sp = space_containing(addr); 2863 return sp->block_size(addr); 2864 } 2865 2866 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { 2867 Space* sp = space_containing(addr); 2868 return sp->block_is_obj(addr); 2869 } 2870 2871 bool G1CollectedHeap::supports_tlab_allocation() const { 2872 return true; 2873 } 2874 2875 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { 2876 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes; 2877 } 2878 2879 size_t G1CollectedHeap::tlab_used(Thread* ignored) const { 2880 return young_list()->eden_used_bytes(); 2881 } 2882 2883 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size 2884 // must be smaller than the humongous object limit. 2885 size_t G1CollectedHeap::max_tlab_size() const { 2886 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment); 2887 } 2888 2889 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { 2890 // Return the remaining space in the cur alloc region, but not less than 2891 // the min TLAB size. 2892 2893 // Also, this value can be at most the humongous object threshold, 2894 // since we can't allow tlabs to grow big enough to accommodate 2895 // humongous objects. 2896 2897 HeapRegion* hr = _mutator_alloc_region.get(); 2898 size_t max_tlab = max_tlab_size() * wordSize; 2899 if (hr == NULL) { 2900 return max_tlab; 2901 } else { 2902 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab); 2903 } 2904 } 2905 2906 size_t G1CollectedHeap::max_capacity() const { 2907 return _hrs.reserved().byte_size(); 2908 } 2909 2910 jlong G1CollectedHeap::millis_since_last_gc() { 2911 // assert(false, "NYI"); 2912 return 0; 2913 } 2914 2915 void G1CollectedHeap::prepare_for_verify() { 2916 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) { 2917 ensure_parsability(false); 2918 } 2919 g1_rem_set()->prepare_for_verify(); 2920 } 2921 2922 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr, 2923 VerifyOption vo) { 2924 switch (vo) { 2925 case VerifyOption_G1UsePrevMarking: 2926 return hr->obj_allocated_since_prev_marking(obj); 2927 case VerifyOption_G1UseNextMarking: 2928 return hr->obj_allocated_since_next_marking(obj); 2929 case VerifyOption_G1UseMarkWord: 2930 return false; 2931 default: 2932 ShouldNotReachHere(); 2933 } 2934 return false; // keep some compilers happy 2935 } 2936 2937 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) { 2938 switch (vo) { 2939 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start(); 2940 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start(); 2941 case VerifyOption_G1UseMarkWord: return NULL; 2942 default: ShouldNotReachHere(); 2943 } 2944 return NULL; // keep some compilers happy 2945 } 2946 2947 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) { 2948 switch (vo) { 2949 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj); 2950 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj); 2951 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked(); 2952 default: ShouldNotReachHere(); 2953 } 2954 return false; // keep some compilers happy 2955 } 2956 2957 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) { 2958 switch (vo) { 2959 case VerifyOption_G1UsePrevMarking: return "PTAMS"; 2960 case VerifyOption_G1UseNextMarking: return "NTAMS"; 2961 case VerifyOption_G1UseMarkWord: return "NONE"; 2962 default: ShouldNotReachHere(); 2963 } 2964 return NULL; // keep some compilers happy 2965 } 2966 2967 class VerifyRootsClosure: public OopClosure { 2968 private: 2969 G1CollectedHeap* _g1h; 2970 VerifyOption _vo; 2971 bool _failures; 2972 public: 2973 // _vo == UsePrevMarking -> use "prev" marking information, 2974 // _vo == UseNextMarking -> use "next" marking information, 2975 // _vo == UseMarkWord -> use mark word from object header. 2976 VerifyRootsClosure(VerifyOption vo) : 2977 _g1h(G1CollectedHeap::heap()), 2978 _vo(vo), 2979 _failures(false) { } 2980 2981 bool failures() { return _failures; } 2982 2983 template <class T> void do_oop_nv(T* p) { 2984 T heap_oop = oopDesc::load_heap_oop(p); 2985 if (!oopDesc::is_null(heap_oop)) { 2986 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 2987 if (_g1h->is_obj_dead_cond(obj, _vo)) { 2988 gclog_or_tty->print_cr("Root location "PTR_FORMAT" " 2989 "points to dead obj "PTR_FORMAT, p, (void*) obj); 2990 if (_vo == VerifyOption_G1UseMarkWord) { 2991 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark())); 2992 } 2993 obj->print_on(gclog_or_tty); 2994 _failures = true; 2995 } 2996 } 2997 } 2998 2999 void do_oop(oop* p) { do_oop_nv(p); } 3000 void do_oop(narrowOop* p) { do_oop_nv(p); } 3001 }; 3002 3003 class G1VerifyCodeRootOopClosure: public OopClosure { 3004 G1CollectedHeap* _g1h; 3005 OopClosure* _root_cl; 3006 nmethod* _nm; 3007 VerifyOption _vo; 3008 bool _failures; 3009 3010 template <class T> void do_oop_work(T* p) { 3011 // First verify that this root is live 3012 _root_cl->do_oop(p); 3013 3014 if (!G1VerifyHeapRegionCodeRoots) { 3015 // We're not verifying the code roots attached to heap region. 3016 return; 3017 } 3018 3019 // Don't check the code roots during marking verification in a full GC 3020 if (_vo == VerifyOption_G1UseMarkWord) { 3021 return; 3022 } 3023 3024 // Now verify that the current nmethod (which contains p) is 3025 // in the code root list of the heap region containing the 3026 // object referenced by p. 3027 3028 T heap_oop = oopDesc::load_heap_oop(p); 3029 if (!oopDesc::is_null(heap_oop)) { 3030 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 3031 3032 // Now fetch the region containing the object 3033 HeapRegion* hr = _g1h->heap_region_containing(obj); 3034 HeapRegionRemSet* hrrs = hr->rem_set(); 3035 // Verify that the strong code root list for this region 3036 // contains the nmethod 3037 if (!hrrs->strong_code_roots_list_contains(_nm)) { 3038 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" " 3039 "from nmethod "PTR_FORMAT" not in strong " 3040 "code roots for region ["PTR_FORMAT","PTR_FORMAT")", 3041 p, _nm, hr->bottom(), hr->end()); 3042 _failures = true; 3043 } 3044 } 3045 } 3046 3047 public: 3048 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo): 3049 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {} 3050 3051 void do_oop(oop* p) { do_oop_work(p); } 3052 void do_oop(narrowOop* p) { do_oop_work(p); } 3053 3054 void set_nmethod(nmethod* nm) { _nm = nm; } 3055 bool failures() { return _failures; } 3056 }; 3057 3058 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure { 3059 G1VerifyCodeRootOopClosure* _oop_cl; 3060 3061 public: 3062 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl): 3063 _oop_cl(oop_cl) {} 3064 3065 void do_code_blob(CodeBlob* cb) { 3066 nmethod* nm = cb->as_nmethod_or_null(); 3067 if (nm != NULL) { 3068 _oop_cl->set_nmethod(nm); 3069 nm->oops_do(_oop_cl); 3070 } 3071 } 3072 }; 3073 3074 class YoungRefCounterClosure : public OopClosure { 3075 G1CollectedHeap* _g1h; 3076 int _count; 3077 public: 3078 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {} 3079 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } } 3080 void do_oop(narrowOop* p) { ShouldNotReachHere(); } 3081 3082 int count() { return _count; } 3083 void reset_count() { _count = 0; }; 3084 }; 3085 3086 class VerifyKlassClosure: public KlassClosure { 3087 YoungRefCounterClosure _young_ref_counter_closure; 3088 OopClosure *_oop_closure; 3089 public: 3090 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {} 3091 void do_klass(Klass* k) { 3092 k->oops_do(_oop_closure); 3093 3094 _young_ref_counter_closure.reset_count(); 3095 k->oops_do(&_young_ref_counter_closure); 3096 if (_young_ref_counter_closure.count() > 0) { 3097 guarantee(k->has_modified_oops(), err_msg("Klass %p, has young refs but is not dirty.", k)); 3098 } 3099 } 3100 }; 3101 3102 class VerifyLivenessOopClosure: public OopClosure { 3103 G1CollectedHeap* _g1h; 3104 VerifyOption _vo; 3105 public: 3106 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo): 3107 _g1h(g1h), _vo(vo) 3108 { } 3109 void do_oop(narrowOop *p) { do_oop_work(p); } 3110 void do_oop( oop *p) { do_oop_work(p); } 3111 3112 template <class T> void do_oop_work(T *p) { 3113 oop obj = oopDesc::load_decode_heap_oop(p); 3114 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo), 3115 "Dead object referenced by a not dead object"); 3116 } 3117 }; 3118 3119 class VerifyObjsInRegionClosure: public ObjectClosure { 3120 private: 3121 G1CollectedHeap* _g1h; 3122 size_t _live_bytes; 3123 HeapRegion *_hr; 3124 VerifyOption _vo; 3125 public: 3126 // _vo == UsePrevMarking -> use "prev" marking information, 3127 // _vo == UseNextMarking -> use "next" marking information, 3128 // _vo == UseMarkWord -> use mark word from object header. 3129 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo) 3130 : _live_bytes(0), _hr(hr), _vo(vo) { 3131 _g1h = G1CollectedHeap::heap(); 3132 } 3133 void do_object(oop o) { 3134 VerifyLivenessOopClosure isLive(_g1h, _vo); 3135 assert(o != NULL, "Huh?"); 3136 if (!_g1h->is_obj_dead_cond(o, _vo)) { 3137 // If the object is alive according to the mark word, 3138 // then verify that the marking information agrees. 3139 // Note we can't verify the contra-positive of the 3140 // above: if the object is dead (according to the mark 3141 // word), it may not be marked, or may have been marked 3142 // but has since became dead, or may have been allocated 3143 // since the last marking. 3144 if (_vo == VerifyOption_G1UseMarkWord) { 3145 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch"); 3146 } 3147 3148 o->oop_iterate_no_header(&isLive); 3149 if (!_hr->obj_allocated_since_prev_marking(o)) { 3150 size_t obj_size = o->size(); // Make sure we don't overflow 3151 _live_bytes += (obj_size * HeapWordSize); 3152 } 3153 } 3154 } 3155 size_t live_bytes() { return _live_bytes; } 3156 }; 3157 3158 class PrintObjsInRegionClosure : public ObjectClosure { 3159 HeapRegion *_hr; 3160 G1CollectedHeap *_g1; 3161 public: 3162 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) { 3163 _g1 = G1CollectedHeap::heap(); 3164 }; 3165 3166 void do_object(oop o) { 3167 if (o != NULL) { 3168 HeapWord *start = (HeapWord *) o; 3169 size_t word_sz = o->size(); 3170 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT 3171 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n", 3172 (void*) o, word_sz, 3173 _g1->isMarkedPrev(o), 3174 _g1->isMarkedNext(o), 3175 _hr->obj_allocated_since_prev_marking(o)); 3176 HeapWord *end = start + word_sz; 3177 HeapWord *cur; 3178 int *val; 3179 for (cur = start; cur < end; cur++) { 3180 val = (int *) cur; 3181 gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val); 3182 } 3183 } 3184 } 3185 }; 3186 3187 class VerifyRegionClosure: public HeapRegionClosure { 3188 private: 3189 bool _par; 3190 VerifyOption _vo; 3191 bool _failures; 3192 public: 3193 // _vo == UsePrevMarking -> use "prev" marking information, 3194 // _vo == UseNextMarking -> use "next" marking information, 3195 // _vo == UseMarkWord -> use mark word from object header. 3196 VerifyRegionClosure(bool par, VerifyOption vo) 3197 : _par(par), 3198 _vo(vo), 3199 _failures(false) {} 3200 3201 bool failures() { 3202 return _failures; 3203 } 3204 3205 bool doHeapRegion(HeapRegion* r) { 3206 if (!r->continuesHumongous()) { 3207 bool failures = false; 3208 r->verify(_vo, &failures); 3209 if (failures) { 3210 _failures = true; 3211 } else { 3212 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo); 3213 r->object_iterate(¬_dead_yet_cl); 3214 if (_vo != VerifyOption_G1UseNextMarking) { 3215 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) { 3216 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] " 3217 "max_live_bytes "SIZE_FORMAT" " 3218 "< calculated "SIZE_FORMAT, 3219 r->bottom(), r->end(), 3220 r->max_live_bytes(), 3221 not_dead_yet_cl.live_bytes()); 3222 _failures = true; 3223 } 3224 } else { 3225 // When vo == UseNextMarking we cannot currently do a sanity 3226 // check on the live bytes as the calculation has not been 3227 // finalized yet. 3228 } 3229 } 3230 } 3231 return false; // stop the region iteration if we hit a failure 3232 } 3233 }; 3234 3235 // This is the task used for parallel verification of the heap regions 3236 3237 class G1ParVerifyTask: public AbstractGangTask { 3238 private: 3239 G1CollectedHeap* _g1h; 3240 VerifyOption _vo; 3241 bool _failures; 3242 3243 public: 3244 // _vo == UsePrevMarking -> use "prev" marking information, 3245 // _vo == UseNextMarking -> use "next" marking information, 3246 // _vo == UseMarkWord -> use mark word from object header. 3247 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) : 3248 AbstractGangTask("Parallel verify task"), 3249 _g1h(g1h), 3250 _vo(vo), 3251 _failures(false) { } 3252 3253 bool failures() { 3254 return _failures; 3255 } 3256 3257 void work(uint worker_id) { 3258 HandleMark hm; 3259 VerifyRegionClosure blk(true, _vo); 3260 _g1h->heap_region_par_iterate_chunked(&blk, worker_id, 3261 _g1h->workers()->active_workers(), 3262 HeapRegion::ParVerifyClaimValue); 3263 if (blk.failures()) { 3264 _failures = true; 3265 } 3266 } 3267 }; 3268 3269 void G1CollectedHeap::verify(bool silent, VerifyOption vo) { 3270 if (SafepointSynchronize::is_at_safepoint()) { 3271 assert(Thread::current()->is_VM_thread(), 3272 "Expected to be executed serially by the VM thread at this point"); 3273 3274 if (!silent) { gclog_or_tty->print("Roots "); } 3275 VerifyRootsClosure rootsCl(vo); 3276 VerifyKlassClosure klassCl(this, &rootsCl); 3277 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false); 3278 3279 // We apply the relevant closures to all the oops in the 3280 // system dictionary, class loader data graph, the string table 3281 // and the nmethods in the code cache. 3282 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo); 3283 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl); 3284 3285 process_all_roots(true, // activate StrongRootsScope 3286 SO_AllCodeCache, // roots scanning options 3287 &rootsCl, 3288 &cldCl, 3289 &blobsCl); 3290 3291 bool failures = rootsCl.failures() || codeRootsCl.failures(); 3292 3293 if (vo != VerifyOption_G1UseMarkWord) { 3294 // If we're verifying during a full GC then the region sets 3295 // will have been torn down at the start of the GC. Therefore 3296 // verifying the region sets will fail. So we only verify 3297 // the region sets when not in a full GC. 3298 if (!silent) { gclog_or_tty->print("HeapRegionSets "); } 3299 verify_region_sets(); 3300 } 3301 3302 if (!silent) { gclog_or_tty->print("HeapRegions "); } 3303 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) { 3304 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue), 3305 "sanity check"); 3306 3307 G1ParVerifyTask task(this, vo); 3308 assert(UseDynamicNumberOfGCThreads || 3309 workers()->active_workers() == workers()->total_workers(), 3310 "If not dynamic should be using all the workers"); 3311 int n_workers = workers()->active_workers(); 3312 set_par_threads(n_workers); 3313 workers()->run_task(&task); 3314 set_par_threads(0); 3315 if (task.failures()) { 3316 failures = true; 3317 } 3318 3319 // Checks that the expected amount of parallel work was done. 3320 // The implication is that n_workers is > 0. 3321 assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue), 3322 "sanity check"); 3323 3324 reset_heap_region_claim_values(); 3325 3326 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue), 3327 "sanity check"); 3328 } else { 3329 VerifyRegionClosure blk(false, vo); 3330 heap_region_iterate(&blk); 3331 if (blk.failures()) { 3332 failures = true; 3333 } 3334 } 3335 if (!silent) gclog_or_tty->print("RemSet "); 3336 rem_set()->verify(); 3337 3338 if (G1StringDedup::is_enabled()) { 3339 if (!silent) gclog_or_tty->print("StrDedup "); 3340 G1StringDedup::verify(); 3341 } 3342 3343 if (failures) { 3344 gclog_or_tty->print_cr("Heap:"); 3345 // It helps to have the per-region information in the output to 3346 // help us track down what went wrong. This is why we call 3347 // print_extended_on() instead of print_on(). 3348 print_extended_on(gclog_or_tty); 3349 gclog_or_tty->cr(); 3350 #ifndef PRODUCT 3351 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) { 3352 concurrent_mark()->print_reachable("at-verification-failure", 3353 vo, false /* all */); 3354 } 3355 #endif 3356 gclog_or_tty->flush(); 3357 } 3358 guarantee(!failures, "there should not have been any failures"); 3359 } else { 3360 if (!silent) { 3361 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet"); 3362 if (G1StringDedup::is_enabled()) { 3363 gclog_or_tty->print(", StrDedup"); 3364 } 3365 gclog_or_tty->print(") "); 3366 } 3367 } 3368 } 3369 3370 void G1CollectedHeap::verify(bool silent) { 3371 verify(silent, VerifyOption_G1UsePrevMarking); 3372 } 3373 3374 double G1CollectedHeap::verify(bool guard, const char* msg) { 3375 double verify_time_ms = 0.0; 3376 3377 if (guard && total_collections() >= VerifyGCStartAt) { 3378 double verify_start = os::elapsedTime(); 3379 HandleMark hm; // Discard invalid handles created during verification 3380 prepare_for_verify(); 3381 Universe::verify(VerifyOption_G1UsePrevMarking, msg); 3382 verify_time_ms = (os::elapsedTime() - verify_start) * 1000; 3383 } 3384 3385 return verify_time_ms; 3386 } 3387 3388 void G1CollectedHeap::verify_before_gc() { 3389 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:"); 3390 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms); 3391 } 3392 3393 void G1CollectedHeap::verify_after_gc() { 3394 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:"); 3395 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms); 3396 } 3397 3398 class PrintRegionClosure: public HeapRegionClosure { 3399 outputStream* _st; 3400 public: 3401 PrintRegionClosure(outputStream* st) : _st(st) {} 3402 bool doHeapRegion(HeapRegion* r) { 3403 r->print_on(_st); 3404 return false; 3405 } 3406 }; 3407 3408 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 3409 const HeapRegion* hr, 3410 const VerifyOption vo) const { 3411 switch (vo) { 3412 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); 3413 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); 3414 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked(); 3415 default: ShouldNotReachHere(); 3416 } 3417 return false; // keep some compilers happy 3418 } 3419 3420 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 3421 const VerifyOption vo) const { 3422 switch (vo) { 3423 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); 3424 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); 3425 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked(); 3426 default: ShouldNotReachHere(); 3427 } 3428 return false; // keep some compilers happy 3429 } 3430 3431 void G1CollectedHeap::print_on(outputStream* st) const { 3432 st->print(" %-20s", "garbage-first heap"); 3433 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 3434 capacity()/K, used_unlocked()/K); 3435 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")", 3436 _hrs.reserved().start(), 3437 _hrs.reserved().start() + _hrs.length() + HeapRegion::GrainWords, 3438 _hrs.reserved().end()); 3439 st->cr(); 3440 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); 3441 uint young_regions = _young_list->length(); 3442 st->print("%u young (" SIZE_FORMAT "K), ", young_regions, 3443 (size_t) young_regions * HeapRegion::GrainBytes / K); 3444 uint survivor_regions = g1_policy()->recorded_survivor_regions(); 3445 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, 3446 (size_t) survivor_regions * HeapRegion::GrainBytes / K); 3447 st->cr(); 3448 MetaspaceAux::print_on(st); 3449 } 3450 3451 void G1CollectedHeap::print_extended_on(outputStream* st) const { 3452 print_on(st); 3453 3454 // Print the per-region information. 3455 st->cr(); 3456 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), " 3457 "HS=humongous(starts), HC=humongous(continues), " 3458 "CS=collection set, F=free, TS=gc time stamp, " 3459 "PTAMS=previous top-at-mark-start, " 3460 "NTAMS=next top-at-mark-start)"); 3461 PrintRegionClosure blk(st); 3462 heap_region_iterate(&blk); 3463 } 3464 3465 void G1CollectedHeap::print_on_error(outputStream* st) const { 3466 this->CollectedHeap::print_on_error(st); 3467 3468 if (_cm != NULL) { 3469 st->cr(); 3470 _cm->print_on_error(st); 3471 } 3472 } 3473 3474 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const { 3475 if (G1CollectedHeap::use_parallel_gc_threads()) { 3476 workers()->print_worker_threads_on(st); 3477 } 3478 _cmThread->print_on(st); 3479 st->cr(); 3480 _cm->print_worker_threads_on(st); 3481 _cg1r->print_worker_threads_on(st); 3482 if (G1StringDedup::is_enabled()) { 3483 G1StringDedup::print_worker_threads_on(st); 3484 } 3485 } 3486 3487 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { 3488 if (G1CollectedHeap::use_parallel_gc_threads()) { 3489 workers()->threads_do(tc); 3490 } 3491 tc->do_thread(_cmThread); 3492 _cg1r->threads_do(tc); 3493 if (G1StringDedup::is_enabled()) { 3494 G1StringDedup::threads_do(tc); 3495 } 3496 } 3497 3498 void G1CollectedHeap::print_tracing_info() const { 3499 // We'll overload this to mean "trace GC pause statistics." 3500 if (TraceGen0Time || TraceGen1Time) { 3501 // The "G1CollectorPolicy" is keeping track of these stats, so delegate 3502 // to that. 3503 g1_policy()->print_tracing_info(); 3504 } 3505 if (G1SummarizeRSetStats) { 3506 g1_rem_set()->print_summary_info(); 3507 } 3508 if (G1SummarizeConcMark) { 3509 concurrent_mark()->print_summary_info(); 3510 } 3511 g1_policy()->print_yg_surv_rate_info(); 3512 SpecializationStats::print(); 3513 } 3514 3515 #ifndef PRODUCT 3516 // Helpful for debugging RSet issues. 3517 3518 class PrintRSetsClosure : public HeapRegionClosure { 3519 private: 3520 const char* _msg; 3521 size_t _occupied_sum; 3522 3523 public: 3524 bool doHeapRegion(HeapRegion* r) { 3525 HeapRegionRemSet* hrrs = r->rem_set(); 3526 size_t occupied = hrrs->occupied(); 3527 _occupied_sum += occupied; 3528 3529 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT, 3530 HR_FORMAT_PARAMS(r)); 3531 if (occupied == 0) { 3532 gclog_or_tty->print_cr(" RSet is empty"); 3533 } else { 3534 hrrs->print(); 3535 } 3536 gclog_or_tty->print_cr("----------"); 3537 return false; 3538 } 3539 3540 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { 3541 gclog_or_tty->cr(); 3542 gclog_or_tty->print_cr("========================================"); 3543 gclog_or_tty->print_cr("%s", msg); 3544 gclog_or_tty->cr(); 3545 } 3546 3547 ~PrintRSetsClosure() { 3548 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum); 3549 gclog_or_tty->print_cr("========================================"); 3550 gclog_or_tty->cr(); 3551 } 3552 }; 3553 3554 void G1CollectedHeap::print_cset_rsets() { 3555 PrintRSetsClosure cl("Printing CSet RSets"); 3556 collection_set_iterate(&cl); 3557 } 3558 3559 void G1CollectedHeap::print_all_rsets() { 3560 PrintRSetsClosure cl("Printing All RSets");; 3561 heap_region_iterate(&cl); 3562 } 3563 #endif // PRODUCT 3564 3565 G1CollectedHeap* G1CollectedHeap::heap() { 3566 assert(_sh->kind() == CollectedHeap::G1CollectedHeap, 3567 "not a garbage-first heap"); 3568 return _g1h; 3569 } 3570 3571 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) { 3572 // always_do_update_barrier = false; 3573 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 3574 // Fill TLAB's and such 3575 accumulate_statistics_all_tlabs(); 3576 ensure_parsability(true); 3577 3578 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) && 3579 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) { 3580 g1_rem_set()->print_periodic_summary_info("Before GC RS summary"); 3581 } 3582 } 3583 3584 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) { 3585 3586 if (G1SummarizeRSetStats && 3587 (G1SummarizeRSetStatsPeriod > 0) && 3588 // we are at the end of the GC. Total collections has already been increased. 3589 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) { 3590 g1_rem_set()->print_periodic_summary_info("After GC RS summary"); 3591 } 3592 3593 // FIXME: what is this about? 3594 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" 3595 // is set. 3596 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(), 3597 "derived pointer present")); 3598 // always_do_update_barrier = true; 3599 3600 resize_all_tlabs(); 3601 3602 // We have just completed a GC. Update the soft reference 3603 // policy with the new heap occupancy 3604 Universe::update_heap_info_at_gc(); 3605 } 3606 3607 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, 3608 unsigned int gc_count_before, 3609 bool* succeeded, 3610 GCCause::Cause gc_cause) { 3611 assert_heap_not_locked_and_not_at_safepoint(); 3612 g1_policy()->record_stop_world_start(); 3613 VM_G1IncCollectionPause op(gc_count_before, 3614 word_size, 3615 false, /* should_initiate_conc_mark */ 3616 g1_policy()->max_pause_time_ms(), 3617 gc_cause); 3618 VMThread::execute(&op); 3619 3620 HeapWord* result = op.result(); 3621 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded(); 3622 assert(result == NULL || ret_succeeded, 3623 "the result should be NULL if the VM did not succeed"); 3624 *succeeded = ret_succeeded; 3625 3626 assert_heap_not_locked(); 3627 return result; 3628 } 3629 3630 void 3631 G1CollectedHeap::doConcurrentMark() { 3632 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); 3633 if (!_cmThread->in_progress()) { 3634 _cmThread->set_started(); 3635 CGC_lock->notify(); 3636 } 3637 } 3638 3639 size_t G1CollectedHeap::pending_card_num() { 3640 size_t extra_cards = 0; 3641 JavaThread *curr = Threads::first(); 3642 while (curr != NULL) { 3643 DirtyCardQueue& dcq = curr->dirty_card_queue(); 3644 extra_cards += dcq.size(); 3645 curr = curr->next(); 3646 } 3647 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 3648 size_t buffer_size = dcqs.buffer_size(); 3649 size_t buffer_num = dcqs.completed_buffers_num(); 3650 3651 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes 3652 // in bytes - not the number of 'entries'. We need to convert 3653 // into a number of cards. 3654 return (buffer_size * buffer_num + extra_cards) / oopSize; 3655 } 3656 3657 size_t G1CollectedHeap::cards_scanned() { 3658 return g1_rem_set()->cardsScanned(); 3659 } 3660 3661 bool G1CollectedHeap::humongous_region_is_always_live(uint index) { 3662 HeapRegion* region = region_at(index); 3663 assert(region->startsHumongous(), "Must start a humongous object"); 3664 return oop(region->bottom())->is_objArray() || !region->rem_set()->is_empty(); 3665 } 3666 3667 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure { 3668 private: 3669 size_t _total_humongous; 3670 size_t _candidate_humongous; 3671 public: 3672 RegisterHumongousWithInCSetFastTestClosure() : _total_humongous(0), _candidate_humongous(0) { 3673 } 3674 3675 virtual bool doHeapRegion(HeapRegion* r) { 3676 if (!r->startsHumongous()) { 3677 return false; 3678 } 3679 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 3680 3681 uint region_idx = r->hrs_index(); 3682 bool is_candidate = !g1h->humongous_region_is_always_live(region_idx); 3683 // Is_candidate already filters out humongous regions with some remembered set. 3684 // This will not lead to humongous object that we mistakenly keep alive because 3685 // during young collection the remembered sets will only be added to. 3686 if (is_candidate) { 3687 g1h->register_humongous_region_with_in_cset_fast_test(region_idx); 3688 _candidate_humongous++; 3689 } 3690 _total_humongous++; 3691 3692 return false; 3693 } 3694 3695 size_t total_humongous() const { return _total_humongous; } 3696 size_t candidate_humongous() const { return _candidate_humongous; } 3697 }; 3698 3699 void G1CollectedHeap::register_humongous_regions_with_in_cset_fast_test() { 3700 if (!G1ReclaimDeadHumongousObjectsAtYoungGC) { 3701 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0, 0); 3702 return; 3703 } 3704 3705 RegisterHumongousWithInCSetFastTestClosure cl; 3706 heap_region_iterate(&cl); 3707 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(cl.total_humongous(), 3708 cl.candidate_humongous()); 3709 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0; 3710 3711 if (_has_humongous_reclaim_candidates) { 3712 clear_humongous_is_live_table(); 3713 } 3714 } 3715 3716 void 3717 G1CollectedHeap::setup_surviving_young_words() { 3718 assert(_surviving_young_words == NULL, "pre-condition"); 3719 uint array_length = g1_policy()->young_cset_region_length(); 3720 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC); 3721 if (_surviving_young_words == NULL) { 3722 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR, 3723 "Not enough space for young surv words summary."); 3724 } 3725 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t)); 3726 #ifdef ASSERT 3727 for (uint i = 0; i < array_length; ++i) { 3728 assert( _surviving_young_words[i] == 0, "memset above" ); 3729 } 3730 #endif // !ASSERT 3731 } 3732 3733 void 3734 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) { 3735 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); 3736 uint array_length = g1_policy()->young_cset_region_length(); 3737 for (uint i = 0; i < array_length; ++i) { 3738 _surviving_young_words[i] += surv_young_words[i]; 3739 } 3740 } 3741 3742 void 3743 G1CollectedHeap::cleanup_surviving_young_words() { 3744 guarantee( _surviving_young_words != NULL, "pre-condition" ); 3745 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words, mtGC); 3746 _surviving_young_words = NULL; 3747 } 3748 3749 #ifdef ASSERT 3750 class VerifyCSetClosure: public HeapRegionClosure { 3751 public: 3752 bool doHeapRegion(HeapRegion* hr) { 3753 // Here we check that the CSet region's RSet is ready for parallel 3754 // iteration. The fields that we'll verify are only manipulated 3755 // when the region is part of a CSet and is collected. Afterwards, 3756 // we reset these fields when we clear the region's RSet (when the 3757 // region is freed) so they are ready when the region is 3758 // re-allocated. The only exception to this is if there's an 3759 // evacuation failure and instead of freeing the region we leave 3760 // it in the heap. In that case, we reset these fields during 3761 // evacuation failure handling. 3762 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification"); 3763 3764 // Here's a good place to add any other checks we'd like to 3765 // perform on CSet regions. 3766 return false; 3767 } 3768 }; 3769 #endif // ASSERT 3770 3771 #if TASKQUEUE_STATS 3772 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) { 3773 st->print_raw_cr("GC Task Stats"); 3774 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); 3775 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); 3776 } 3777 3778 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const { 3779 print_taskqueue_stats_hdr(st); 3780 3781 TaskQueueStats totals; 3782 const int n = workers() != NULL ? workers()->total_workers() : 1; 3783 for (int i = 0; i < n; ++i) { 3784 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr(); 3785 totals += task_queue(i)->stats; 3786 } 3787 st->print_raw("tot "); totals.print(st); st->cr(); 3788 3789 DEBUG_ONLY(totals.verify()); 3790 } 3791 3792 void G1CollectedHeap::reset_taskqueue_stats() { 3793 const int n = workers() != NULL ? workers()->total_workers() : 1; 3794 for (int i = 0; i < n; ++i) { 3795 task_queue(i)->stats.reset(); 3796 } 3797 } 3798 #endif // TASKQUEUE_STATS 3799 3800 void G1CollectedHeap::log_gc_header() { 3801 if (!G1Log::fine()) { 3802 return; 3803 } 3804 3805 gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id()); 3806 3807 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause()) 3808 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)") 3809 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : ""); 3810 3811 gclog_or_tty->print("[%s", (const char*)gc_cause_str); 3812 } 3813 3814 void G1CollectedHeap::log_gc_footer(double pause_time_sec) { 3815 if (!G1Log::fine()) { 3816 return; 3817 } 3818 3819 if (G1Log::finer()) { 3820 if (evacuation_failed()) { 3821 gclog_or_tty->print(" (to-space exhausted)"); 3822 } 3823 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec); 3824 g1_policy()->phase_times()->note_gc_end(); 3825 g1_policy()->phase_times()->print(pause_time_sec); 3826 g1_policy()->print_detailed_heap_transition(); 3827 } else { 3828 if (evacuation_failed()) { 3829 gclog_or_tty->print("--"); 3830 } 3831 g1_policy()->print_heap_transition(); 3832 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec); 3833 } 3834 gclog_or_tty->flush(); 3835 } 3836 3837 bool 3838 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { 3839 assert_at_safepoint(true /* should_be_vm_thread */); 3840 guarantee(!is_gc_active(), "collection is not reentrant"); 3841 3842 if (GC_locker::check_active_before_gc()) { 3843 return false; 3844 } 3845 3846 _gc_timer_stw->register_gc_start(); 3847 3848 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start()); 3849 3850 SvcGCMarker sgcm(SvcGCMarker::MINOR); 3851 ResourceMark rm; 3852 3853 print_heap_before_gc(); 3854 trace_heap_before_gc(_gc_tracer_stw); 3855 3856 verify_region_sets_optional(); 3857 verify_dirty_young_regions(); 3858 3859 // This call will decide whether this pause is an initial-mark 3860 // pause. If it is, during_initial_mark_pause() will return true 3861 // for the duration of this pause. 3862 g1_policy()->decide_on_conc_mark_initiation(); 3863 3864 // We do not allow initial-mark to be piggy-backed on a mixed GC. 3865 assert(!g1_policy()->during_initial_mark_pause() || 3866 g1_policy()->gcs_are_young(), "sanity"); 3867 3868 // We also do not allow mixed GCs during marking. 3869 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity"); 3870 3871 // Record whether this pause is an initial mark. When the current 3872 // thread has completed its logging output and it's safe to signal 3873 // the CM thread, the flag's value in the policy has been reset. 3874 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause(); 3875 3876 // Inner scope for scope based logging, timers, and stats collection 3877 { 3878 EvacuationInfo evacuation_info; 3879 3880 if (g1_policy()->during_initial_mark_pause()) { 3881 // We are about to start a marking cycle, so we increment the 3882 // full collection counter. 3883 increment_old_marking_cycles_started(); 3884 register_concurrent_cycle_start(_gc_timer_stw->gc_start()); 3885 } 3886 3887 _gc_tracer_stw->report_yc_type(yc_type()); 3888 3889 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty); 3890 3891 int active_workers = (G1CollectedHeap::use_parallel_gc_threads() ? 3892 workers()->active_workers() : 1); 3893 double pause_start_sec = os::elapsedTime(); 3894 g1_policy()->phase_times()->note_gc_start(active_workers); 3895 log_gc_header(); 3896 3897 TraceCollectorStats tcs(g1mm()->incremental_collection_counters()); 3898 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause()); 3899 3900 // If the secondary_free_list is not empty, append it to the 3901 // free_list. No need to wait for the cleanup operation to finish; 3902 // the region allocation code will check the secondary_free_list 3903 // and wait if necessary. If the G1StressConcRegionFreeing flag is 3904 // set, skip this step so that the region allocation code has to 3905 // get entries from the secondary_free_list. 3906 if (!G1StressConcRegionFreeing) { 3907 append_secondary_free_list_if_not_empty_with_lock(); 3908 } 3909 3910 assert(check_young_list_well_formed(), "young list should be well formed"); 3911 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue), 3912 "sanity check"); 3913 3914 // Don't dynamically change the number of GC threads this early. A value of 3915 // 0 is used to indicate serial work. When parallel work is done, 3916 // it will be set. 3917 3918 { // Call to jvmpi::post_class_unload_events must occur outside of active GC 3919 IsGCActiveMark x; 3920 3921 gc_prologue(false); 3922 increment_total_collections(false /* full gc */); 3923 increment_gc_time_stamp(); 3924 3925 verify_before_gc(); 3926 check_bitmaps("GC Start"); 3927 3928 COMPILER2_PRESENT(DerivedPointerTable::clear()); 3929 3930 // Please see comment in g1CollectedHeap.hpp and 3931 // G1CollectedHeap::ref_processing_init() to see how 3932 // reference processing currently works in G1. 3933 3934 // Enable discovery in the STW reference processor 3935 ref_processor_stw()->enable_discovery(true /*verify_disabled*/, 3936 true /*verify_no_refs*/); 3937 3938 { 3939 // We want to temporarily turn off discovery by the 3940 // CM ref processor, if necessary, and turn it back on 3941 // on again later if we do. Using a scoped 3942 // NoRefDiscovery object will do this. 3943 NoRefDiscovery no_cm_discovery(ref_processor_cm()); 3944 3945 // Forget the current alloc region (we might even choose it to be part 3946 // of the collection set!). 3947 release_mutator_alloc_region(); 3948 3949 // We should call this after we retire the mutator alloc 3950 // region(s) so that all the ALLOC / RETIRE events are generated 3951 // before the start GC event. 3952 _hr_printer.start_gc(false /* full */, (size_t) total_collections()); 3953 3954 // This timing is only used by the ergonomics to handle our pause target. 3955 // It is unclear why this should not include the full pause. We will 3956 // investigate this in CR 7178365. 3957 // 3958 // Preserving the old comment here if that helps the investigation: 3959 // 3960 // The elapsed time induced by the start time below deliberately elides 3961 // the possible verification above. 3962 double sample_start_time_sec = os::elapsedTime(); 3963 3964 #if YOUNG_LIST_VERBOSE 3965 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:"); 3966 _young_list->print(); 3967 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 3968 #endif // YOUNG_LIST_VERBOSE 3969 3970 g1_policy()->record_collection_pause_start(sample_start_time_sec); 3971 3972 double scan_wait_start = os::elapsedTime(); 3973 // We have to wait until the CM threads finish scanning the 3974 // root regions as it's the only way to ensure that all the 3975 // objects on them have been correctly scanned before we start 3976 // moving them during the GC. 3977 bool waited = _cm->root_regions()->wait_until_scan_finished(); 3978 double wait_time_ms = 0.0; 3979 if (waited) { 3980 double scan_wait_end = os::elapsedTime(); 3981 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0; 3982 } 3983 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms); 3984 3985 #if YOUNG_LIST_VERBOSE 3986 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:"); 3987 _young_list->print(); 3988 #endif // YOUNG_LIST_VERBOSE 3989 3990 if (g1_policy()->during_initial_mark_pause()) { 3991 concurrent_mark()->checkpointRootsInitialPre(); 3992 } 3993 3994 #if YOUNG_LIST_VERBOSE 3995 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:"); 3996 _young_list->print(); 3997 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 3998 #endif // YOUNG_LIST_VERBOSE 3999 4000 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info); 4001 4002 register_humongous_regions_with_in_cset_fast_test(); 4003 4004 _cm->note_start_of_gc(); 4005 // We should not verify the per-thread SATB buffers given that 4006 // we have not filtered them yet (we'll do so during the 4007 // GC). We also call this after finalize_cset() to 4008 // ensure that the CSet has been finalized. 4009 _cm->verify_no_cset_oops(true /* verify_stacks */, 4010 true /* verify_enqueued_buffers */, 4011 false /* verify_thread_buffers */, 4012 true /* verify_fingers */); 4013 4014 if (_hr_printer.is_active()) { 4015 HeapRegion* hr = g1_policy()->collection_set(); 4016 while (hr != NULL) { 4017 G1HRPrinter::RegionType type; 4018 if (!hr->is_young()) { 4019 type = G1HRPrinter::Old; 4020 } else if (hr->is_survivor()) { 4021 type = G1HRPrinter::Survivor; 4022 } else { 4023 type = G1HRPrinter::Eden; 4024 } 4025 _hr_printer.cset(hr); 4026 hr = hr->next_in_collection_set(); 4027 } 4028 } 4029 4030 #ifdef ASSERT 4031 VerifyCSetClosure cl; 4032 collection_set_iterate(&cl); 4033 #endif // ASSERT 4034 4035 setup_surviving_young_words(); 4036 4037 // Initialize the GC alloc regions. 4038 init_gc_alloc_regions(evacuation_info); 4039 4040 // Actually do the work... 4041 evacuate_collection_set(evacuation_info); 4042 4043 // We do this to mainly verify the per-thread SATB buffers 4044 // (which have been filtered by now) since we didn't verify 4045 // them earlier. No point in re-checking the stacks / enqueued 4046 // buffers given that the CSet has not changed since last time 4047 // we checked. 4048 _cm->verify_no_cset_oops(false /* verify_stacks */, 4049 false /* verify_enqueued_buffers */, 4050 true /* verify_thread_buffers */, 4051 true /* verify_fingers */); 4052 4053 free_collection_set(g1_policy()->collection_set(), evacuation_info); 4054 4055 eagerly_reclaim_humongous_regions(); 4056 4057 g1_policy()->clear_collection_set(); 4058 4059 cleanup_surviving_young_words(); 4060 4061 // Start a new incremental collection set for the next pause. 4062 g1_policy()->start_incremental_cset_building(); 4063 4064 clear_cset_fast_test(); 4065 4066 _young_list->reset_sampled_info(); 4067 4068 // Don't check the whole heap at this point as the 4069 // GC alloc regions from this pause have been tagged 4070 // as survivors and moved on to the survivor list. 4071 // Survivor regions will fail the !is_young() check. 4072 assert(check_young_list_empty(false /* check_heap */), 4073 "young list should be empty"); 4074 4075 #if YOUNG_LIST_VERBOSE 4076 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:"); 4077 _young_list->print(); 4078 #endif // YOUNG_LIST_VERBOSE 4079 4080 g1_policy()->record_survivor_regions(_young_list->survivor_length(), 4081 _young_list->first_survivor_region(), 4082 _young_list->last_survivor_region()); 4083 4084 _young_list->reset_auxilary_lists(); 4085 4086 if (evacuation_failed()) { 4087 _summary_bytes_used = recalculate_used(); 4088 uint n_queues = MAX2((int)ParallelGCThreads, 1); 4089 for (uint i = 0; i < n_queues; i++) { 4090 if (_evacuation_failed_info_array[i].has_failed()) { 4091 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]); 4092 } 4093 } 4094 } else { 4095 // The "used" of the the collection set have already been subtracted 4096 // when they were freed. Add in the bytes evacuated. 4097 _summary_bytes_used += g1_policy()->bytes_copied_during_gc(); 4098 } 4099 4100 if (g1_policy()->during_initial_mark_pause()) { 4101 // We have to do this before we notify the CM threads that 4102 // they can start working to make sure that all the 4103 // appropriate initialization is done on the CM object. 4104 concurrent_mark()->checkpointRootsInitialPost(); 4105 set_marking_started(); 4106 // Note that we don't actually trigger the CM thread at 4107 // this point. We do that later when we're sure that 4108 // the current thread has completed its logging output. 4109 } 4110 4111 allocate_dummy_regions(); 4112 4113 #if YOUNG_LIST_VERBOSE 4114 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:"); 4115 _young_list->print(); 4116 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 4117 #endif // YOUNG_LIST_VERBOSE 4118 4119 init_mutator_alloc_region(); 4120 4121 { 4122 size_t expand_bytes = g1_policy()->expansion_amount(); 4123 if (expand_bytes > 0) { 4124 size_t bytes_before = capacity(); 4125 // No need for an ergo verbose message here, 4126 // expansion_amount() does this when it returns a value > 0. 4127 if (!expand(expand_bytes)) { 4128 // We failed to expand the heap. Cannot do anything about it. 4129 } 4130 } 4131 } 4132 4133 // We redo the verification but now wrt to the new CSet which 4134 // has just got initialized after the previous CSet was freed. 4135 _cm->verify_no_cset_oops(true /* verify_stacks */, 4136 true /* verify_enqueued_buffers */, 4137 true /* verify_thread_buffers */, 4138 true /* verify_fingers */); 4139 _cm->note_end_of_gc(); 4140 4141 // This timing is only used by the ergonomics to handle our pause target. 4142 // It is unclear why this should not include the full pause. We will 4143 // investigate this in CR 7178365. 4144 double sample_end_time_sec = os::elapsedTime(); 4145 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; 4146 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info); 4147 4148 MemoryService::track_memory_usage(); 4149 4150 // In prepare_for_verify() below we'll need to scan the deferred 4151 // update buffers to bring the RSets up-to-date if 4152 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning 4153 // the update buffers we'll probably need to scan cards on the 4154 // regions we just allocated to (i.e., the GC alloc 4155 // regions). However, during the last GC we called 4156 // set_saved_mark() on all the GC alloc regions, so card 4157 // scanning might skip the [saved_mark_word()...top()] area of 4158 // those regions (i.e., the area we allocated objects into 4159 // during the last GC). But it shouldn't. Given that 4160 // saved_mark_word() is conditional on whether the GC time stamp 4161 // on the region is current or not, by incrementing the GC time 4162 // stamp here we invalidate all the GC time stamps on all the 4163 // regions and saved_mark_word() will simply return top() for 4164 // all the regions. This is a nicer way of ensuring this rather 4165 // than iterating over the regions and fixing them. In fact, the 4166 // GC time stamp increment here also ensures that 4167 // saved_mark_word() will return top() between pauses, i.e., 4168 // during concurrent refinement. So we don't need the 4169 // is_gc_active() check to decided which top to use when 4170 // scanning cards (see CR 7039627). 4171 increment_gc_time_stamp(); 4172 4173 verify_after_gc(); 4174 check_bitmaps("GC End"); 4175 4176 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 4177 ref_processor_stw()->verify_no_references_recorded(); 4178 4179 // CM reference discovery will be re-enabled if necessary. 4180 } 4181 4182 // We should do this after we potentially expand the heap so 4183 // that all the COMMIT events are generated before the end GC 4184 // event, and after we retire the GC alloc regions so that all 4185 // RETIRE events are generated before the end GC event. 4186 _hr_printer.end_gc(false /* full */, (size_t) total_collections()); 4187 4188 #ifdef TRACESPINNING 4189 ParallelTaskTerminator::print_termination_counts(); 4190 #endif 4191 4192 gc_epilogue(false); 4193 } 4194 4195 // Print the remainder of the GC log output. 4196 log_gc_footer(os::elapsedTime() - pause_start_sec); 4197 4198 // It is not yet to safe to tell the concurrent mark to 4199 // start as we have some optional output below. We don't want the 4200 // output from the concurrent mark thread interfering with this 4201 // logging output either. 4202 4203 _hrs.verify_optional(); 4204 verify_region_sets_optional(); 4205 4206 TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats()); 4207 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); 4208 4209 print_heap_after_gc(); 4210 trace_heap_after_gc(_gc_tracer_stw); 4211 4212 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 4213 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 4214 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 4215 // before any GC notifications are raised. 4216 g1mm()->update_sizes(); 4217 4218 _gc_tracer_stw->report_evacuation_info(&evacuation_info); 4219 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold()); 4220 _gc_timer_stw->register_gc_end(); 4221 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions()); 4222 } 4223 // It should now be safe to tell the concurrent mark thread to start 4224 // without its logging output interfering with the logging output 4225 // that came from the pause. 4226 4227 if (should_start_conc_mark) { 4228 // CAUTION: after the doConcurrentMark() call below, 4229 // the concurrent marking thread(s) could be running 4230 // concurrently with us. Make sure that anything after 4231 // this point does not assume that we are the only GC thread 4232 // running. Note: of course, the actual marking work will 4233 // not start until the safepoint itself is released in 4234 // SuspendibleThreadSet::desynchronize(). 4235 doConcurrentMark(); 4236 } 4237 4238 return true; 4239 } 4240 4241 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose) 4242 { 4243 size_t gclab_word_size; 4244 switch (purpose) { 4245 case GCAllocForSurvived: 4246 gclab_word_size = _survivor_plab_stats.desired_plab_sz(); 4247 break; 4248 case GCAllocForTenured: 4249 gclab_word_size = _old_plab_stats.desired_plab_sz(); 4250 break; 4251 default: 4252 assert(false, "unknown GCAllocPurpose"); 4253 gclab_word_size = _old_plab_stats.desired_plab_sz(); 4254 break; 4255 } 4256 4257 // Prevent humongous PLAB sizes for two reasons: 4258 // * PLABs are allocated using a similar paths as oops, but should 4259 // never be in a humongous region 4260 // * Allowing humongous PLABs needlessly churns the region free lists 4261 return MIN2(_humongous_object_threshold_in_words, gclab_word_size); 4262 } 4263 4264 void G1CollectedHeap::init_mutator_alloc_region() { 4265 assert(_mutator_alloc_region.get() == NULL, "pre-condition"); 4266 _mutator_alloc_region.init(); 4267 } 4268 4269 void G1CollectedHeap::release_mutator_alloc_region() { 4270 _mutator_alloc_region.release(); 4271 assert(_mutator_alloc_region.get() == NULL, "post-condition"); 4272 } 4273 4274 void G1CollectedHeap::use_retained_old_gc_alloc_region(EvacuationInfo& evacuation_info) { 4275 HeapRegion* retained_region = _retained_old_gc_alloc_region; 4276 _retained_old_gc_alloc_region = NULL; 4277 4278 // We will discard the current GC alloc region if: 4279 // a) it's in the collection set (it can happen!), 4280 // b) it's already full (no point in using it), 4281 // c) it's empty (this means that it was emptied during 4282 // a cleanup and it should be on the free list now), or 4283 // d) it's humongous (this means that it was emptied 4284 // during a cleanup and was added to the free list, but 4285 // has been subsequently used to allocate a humongous 4286 // object that may be less than the region size). 4287 if (retained_region != NULL && 4288 !retained_region->in_collection_set() && 4289 !(retained_region->top() == retained_region->end()) && 4290 !retained_region->is_empty() && 4291 !retained_region->isHumongous()) { 4292 retained_region->record_top_and_timestamp(); 4293 // The retained region was added to the old region set when it was 4294 // retired. We have to remove it now, since we don't allow regions 4295 // we allocate to in the region sets. We'll re-add it later, when 4296 // it's retired again. 4297 _old_set.remove(retained_region); 4298 bool during_im = g1_policy()->during_initial_mark_pause(); 4299 retained_region->note_start_of_copying(during_im); 4300 _old_gc_alloc_region.set(retained_region); 4301 _hr_printer.reuse(retained_region); 4302 evacuation_info.set_alloc_regions_used_before(retained_region->used()); 4303 } 4304 } 4305 4306 void G1CollectedHeap::init_gc_alloc_regions(EvacuationInfo& evacuation_info) { 4307 assert_at_safepoint(true /* should_be_vm_thread */); 4308 4309 _survivor_gc_alloc_region.init(); 4310 _old_gc_alloc_region.init(); 4311 4312 use_retained_old_gc_alloc_region(evacuation_info); 4313 } 4314 4315 void G1CollectedHeap::release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info) { 4316 evacuation_info.set_allocation_regions(_survivor_gc_alloc_region.count() + 4317 _old_gc_alloc_region.count()); 4318 _survivor_gc_alloc_region.release(); 4319 // If we have an old GC alloc region to release, we'll save it in 4320 // _retained_old_gc_alloc_region. If we don't 4321 // _retained_old_gc_alloc_region will become NULL. This is what we 4322 // want either way so no reason to check explicitly for either 4323 // condition. 4324 _retained_old_gc_alloc_region = _old_gc_alloc_region.release(); 4325 4326 if (ResizePLAB) { 4327 _survivor_plab_stats.adjust_desired_plab_sz(no_of_gc_workers); 4328 _old_plab_stats.adjust_desired_plab_sz(no_of_gc_workers); 4329 } 4330 } 4331 4332 void G1CollectedHeap::abandon_gc_alloc_regions() { 4333 assert(_survivor_gc_alloc_region.get() == NULL, "pre-condition"); 4334 assert(_old_gc_alloc_region.get() == NULL, "pre-condition"); 4335 _retained_old_gc_alloc_region = NULL; 4336 } 4337 4338 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) { 4339 _drain_in_progress = false; 4340 set_evac_failure_closure(cl); 4341 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true); 4342 } 4343 4344 void G1CollectedHeap::finalize_for_evac_failure() { 4345 assert(_evac_failure_scan_stack != NULL && 4346 _evac_failure_scan_stack->length() == 0, 4347 "Postcondition"); 4348 assert(!_drain_in_progress, "Postcondition"); 4349 delete _evac_failure_scan_stack; 4350 _evac_failure_scan_stack = NULL; 4351 } 4352 4353 void G1CollectedHeap::remove_self_forwarding_pointers() { 4354 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity"); 4355 4356 double remove_self_forwards_start = os::elapsedTime(); 4357 4358 G1ParRemoveSelfForwardPtrsTask rsfp_task(this); 4359 4360 if (G1CollectedHeap::use_parallel_gc_threads()) { 4361 set_par_threads(); 4362 workers()->run_task(&rsfp_task); 4363 set_par_threads(0); 4364 } else { 4365 rsfp_task.work(0); 4366 } 4367 4368 assert(check_cset_heap_region_claim_values(HeapRegion::ParEvacFailureClaimValue), "sanity"); 4369 4370 // Reset the claim values in the regions in the collection set. 4371 reset_cset_heap_region_claim_values(); 4372 4373 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity"); 4374 4375 // Now restore saved marks, if any. 4376 assert(_objs_with_preserved_marks.size() == 4377 _preserved_marks_of_objs.size(), "Both or none."); 4378 while (!_objs_with_preserved_marks.is_empty()) { 4379 oop obj = _objs_with_preserved_marks.pop(); 4380 markOop m = _preserved_marks_of_objs.pop(); 4381 obj->set_mark(m); 4382 } 4383 _objs_with_preserved_marks.clear(true); 4384 _preserved_marks_of_objs.clear(true); 4385 4386 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0); 4387 } 4388 4389 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) { 4390 _evac_failure_scan_stack->push(obj); 4391 } 4392 4393 void G1CollectedHeap::drain_evac_failure_scan_stack() { 4394 assert(_evac_failure_scan_stack != NULL, "precondition"); 4395 4396 while (_evac_failure_scan_stack->length() > 0) { 4397 oop obj = _evac_failure_scan_stack->pop(); 4398 _evac_failure_closure->set_region(heap_region_containing(obj)); 4399 obj->oop_iterate_backwards(_evac_failure_closure); 4400 } 4401 } 4402 4403 oop 4404 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state, 4405 oop old) { 4406 assert(obj_in_cs(old), 4407 err_msg("obj: "PTR_FORMAT" should still be in the CSet", 4408 (HeapWord*) old)); 4409 markOop m = old->mark(); 4410 oop forward_ptr = old->forward_to_atomic(old); 4411 if (forward_ptr == NULL) { 4412 // Forward-to-self succeeded. 4413 assert(_par_scan_state != NULL, "par scan state"); 4414 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure(); 4415 uint queue_num = _par_scan_state->queue_num(); 4416 4417 _evacuation_failed = true; 4418 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size()); 4419 if (_evac_failure_closure != cl) { 4420 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag); 4421 assert(!_drain_in_progress, 4422 "Should only be true while someone holds the lock."); 4423 // Set the global evac-failure closure to the current thread's. 4424 assert(_evac_failure_closure == NULL, "Or locking has failed."); 4425 set_evac_failure_closure(cl); 4426 // Now do the common part. 4427 handle_evacuation_failure_common(old, m); 4428 // Reset to NULL. 4429 set_evac_failure_closure(NULL); 4430 } else { 4431 // The lock is already held, and this is recursive. 4432 assert(_drain_in_progress, "This should only be the recursive case."); 4433 handle_evacuation_failure_common(old, m); 4434 } 4435 return old; 4436 } else { 4437 // Forward-to-self failed. Either someone else managed to allocate 4438 // space for this object (old != forward_ptr) or they beat us in 4439 // self-forwarding it (old == forward_ptr). 4440 assert(old == forward_ptr || !obj_in_cs(forward_ptr), 4441 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" " 4442 "should not be in the CSet", 4443 (HeapWord*) old, (HeapWord*) forward_ptr)); 4444 return forward_ptr; 4445 } 4446 } 4447 4448 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) { 4449 preserve_mark_if_necessary(old, m); 4450 4451 HeapRegion* r = heap_region_containing(old); 4452 if (!r->evacuation_failed()) { 4453 r->set_evacuation_failed(true); 4454 _hr_printer.evac_failure(r); 4455 } 4456 4457 push_on_evac_failure_scan_stack(old); 4458 4459 if (!_drain_in_progress) { 4460 // prevent recursion in copy_to_survivor_space() 4461 _drain_in_progress = true; 4462 drain_evac_failure_scan_stack(); 4463 _drain_in_progress = false; 4464 } 4465 } 4466 4467 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) { 4468 assert(evacuation_failed(), "Oversaving!"); 4469 // We want to call the "for_promotion_failure" version only in the 4470 // case of a promotion failure. 4471 if (m->must_be_preserved_for_promotion_failure(obj)) { 4472 _objs_with_preserved_marks.push(obj); 4473 _preserved_marks_of_objs.push(m); 4474 } 4475 } 4476 4477 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose, 4478 size_t word_size) { 4479 if (purpose == GCAllocForSurvived) { 4480 HeapWord* result = survivor_attempt_allocation(word_size); 4481 if (result != NULL) { 4482 return result; 4483 } else { 4484 // Let's try to allocate in the old gen in case we can fit the 4485 // object there. 4486 return old_attempt_allocation(word_size); 4487 } 4488 } else { 4489 assert(purpose == GCAllocForTenured, "sanity"); 4490 HeapWord* result = old_attempt_allocation(word_size); 4491 if (result != NULL) { 4492 return result; 4493 } else { 4494 // Let's try to allocate in the survivors in case we can fit the 4495 // object there. 4496 return survivor_attempt_allocation(word_size); 4497 } 4498 } 4499 4500 ShouldNotReachHere(); 4501 // Trying to keep some compilers happy. 4502 return NULL; 4503 } 4504 4505 G1ParGCAllocBuffer::G1ParGCAllocBuffer(size_t gclab_word_size) : 4506 ParGCAllocBuffer(gclab_word_size), _retired(true) { } 4507 4508 void G1ParCopyHelper::mark_object(oop obj) { 4509 assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet"); 4510 4511 // We know that the object is not moving so it's safe to read its size. 4512 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id); 4513 } 4514 4515 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) { 4516 assert(from_obj->is_forwarded(), "from obj should be forwarded"); 4517 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee"); 4518 assert(from_obj != to_obj, "should not be self-forwarded"); 4519 4520 assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet"); 4521 assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet"); 4522 4523 // The object might be in the process of being copied by another 4524 // worker so we cannot trust that its to-space image is 4525 // well-formed. So we have to read its size from its from-space 4526 // image which we know should not be changing. 4527 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id); 4528 } 4529 4530 template <class T> 4531 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) { 4532 if (_g1->heap_region_containing_raw(new_obj)->is_young()) { 4533 _scanned_klass->record_modified_oops(); 4534 } 4535 } 4536 4537 template <G1Barrier barrier, G1Mark do_mark_object> 4538 template <class T> 4539 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) { 4540 T heap_oop = oopDesc::load_heap_oop(p); 4541 4542 if (oopDesc::is_null(heap_oop)) { 4543 return; 4544 } 4545 4546 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 4547 4548 assert(_worker_id == _par_scan_state->queue_num(), "sanity"); 4549 4550 G1CollectedHeap::in_cset_state_t state = _g1->in_cset_state(obj); 4551 4552 if (state == G1CollectedHeap::InCSet) { 4553 oop forwardee; 4554 if (obj->is_forwarded()) { 4555 forwardee = obj->forwardee(); 4556 } else { 4557 forwardee = _par_scan_state->copy_to_survivor_space(obj); 4558 } 4559 assert(forwardee != NULL, "forwardee should not be NULL"); 4560 oopDesc::encode_store_heap_oop(p, forwardee); 4561 if (do_mark_object != G1MarkNone && forwardee != obj) { 4562 // If the object is self-forwarded we don't need to explicitly 4563 // mark it, the evacuation failure protocol will do so. 4564 mark_forwarded_object(obj, forwardee); 4565 } 4566 4567 if (barrier == G1BarrierKlass) { 4568 do_klass_barrier(p, forwardee); 4569 } 4570 } else { 4571 if (state == G1CollectedHeap::IsHumongous) { 4572 _g1->set_humongous_is_live(obj); 4573 } 4574 // The object is not in collection set. If we're a root scanning 4575 // closure during an initial mark pause then attempt to mark the object. 4576 if (do_mark_object == G1MarkFromRoot) { 4577 mark_object(obj); 4578 } 4579 } 4580 4581 if (barrier == G1BarrierEvac) { 4582 _par_scan_state->update_rs(_from, p, _worker_id); 4583 } 4584 } 4585 4586 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(oop* p); 4587 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(narrowOop* p); 4588 4589 class G1ParEvacuateFollowersClosure : public VoidClosure { 4590 protected: 4591 G1CollectedHeap* _g1h; 4592 G1ParScanThreadState* _par_scan_state; 4593 RefToScanQueueSet* _queues; 4594 ParallelTaskTerminator* _terminator; 4595 4596 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 4597 RefToScanQueueSet* queues() { return _queues; } 4598 ParallelTaskTerminator* terminator() { return _terminator; } 4599 4600 public: 4601 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h, 4602 G1ParScanThreadState* par_scan_state, 4603 RefToScanQueueSet* queues, 4604 ParallelTaskTerminator* terminator) 4605 : _g1h(g1h), _par_scan_state(par_scan_state), 4606 _queues(queues), _terminator(terminator) {} 4607 4608 void do_void(); 4609 4610 private: 4611 inline bool offer_termination(); 4612 }; 4613 4614 bool G1ParEvacuateFollowersClosure::offer_termination() { 4615 G1ParScanThreadState* const pss = par_scan_state(); 4616 pss->start_term_time(); 4617 const bool res = terminator()->offer_termination(); 4618 pss->end_term_time(); 4619 return res; 4620 } 4621 4622 void G1ParEvacuateFollowersClosure::do_void() { 4623 G1ParScanThreadState* const pss = par_scan_state(); 4624 pss->trim_queue(); 4625 do { 4626 pss->steal_and_trim_queue(queues()); 4627 } while (!offer_termination()); 4628 } 4629 4630 class G1KlassScanClosure : public KlassClosure { 4631 G1ParCopyHelper* _closure; 4632 bool _process_only_dirty; 4633 int _count; 4634 public: 4635 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty) 4636 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {} 4637 void do_klass(Klass* klass) { 4638 // If the klass has not been dirtied we know that there's 4639 // no references into the young gen and we can skip it. 4640 if (!_process_only_dirty || klass->has_modified_oops()) { 4641 // Clean the klass since we're going to scavenge all the metadata. 4642 klass->clear_modified_oops(); 4643 4644 // Tell the closure that this klass is the Klass to scavenge 4645 // and is the one to dirty if oops are left pointing into the young gen. 4646 _closure->set_scanned_klass(klass); 4647 4648 klass->oops_do(_closure); 4649 4650 _closure->set_scanned_klass(NULL); 4651 } 4652 _count++; 4653 } 4654 }; 4655 4656 class G1ParTask : public AbstractGangTask { 4657 protected: 4658 G1CollectedHeap* _g1h; 4659 RefToScanQueueSet *_queues; 4660 ParallelTaskTerminator _terminator; 4661 uint _n_workers; 4662 4663 Mutex _stats_lock; 4664 Mutex* stats_lock() { return &_stats_lock; } 4665 4666 public: 4667 G1ParTask(G1CollectedHeap* g1h, RefToScanQueueSet *task_queues) 4668 : AbstractGangTask("G1 collection"), 4669 _g1h(g1h), 4670 _queues(task_queues), 4671 _terminator(0, _queues), 4672 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true) 4673 {} 4674 4675 RefToScanQueueSet* queues() { return _queues; } 4676 4677 RefToScanQueue *work_queue(int i) { 4678 return queues()->queue(i); 4679 } 4680 4681 ParallelTaskTerminator* terminator() { return &_terminator; } 4682 4683 virtual void set_for_termination(int active_workers) { 4684 // This task calls set_n_termination() in par_non_clean_card_iterate_work() 4685 // in the young space (_par_seq_tasks) in the G1 heap 4686 // for SequentialSubTasksDone. 4687 // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap 4688 // both of which need setting by set_n_termination(). 4689 _g1h->SharedHeap::set_n_termination(active_workers); 4690 _g1h->set_n_termination(active_workers); 4691 terminator()->reset_for_reuse(active_workers); 4692 _n_workers = active_workers; 4693 } 4694 4695 // Helps out with CLD processing. 4696 // 4697 // During InitialMark we need to: 4698 // 1) Scavenge all CLDs for the young GC. 4699 // 2) Mark all objects directly reachable from strong CLDs. 4700 template <G1Mark do_mark_object> 4701 class G1CLDClosure : public CLDClosure { 4702 G1ParCopyClosure<G1BarrierNone, do_mark_object>* _oop_closure; 4703 G1ParCopyClosure<G1BarrierKlass, do_mark_object> _oop_in_klass_closure; 4704 G1KlassScanClosure _klass_in_cld_closure; 4705 bool _claim; 4706 4707 public: 4708 G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure, 4709 bool only_young, bool claim) 4710 : _oop_closure(oop_closure), 4711 _oop_in_klass_closure(oop_closure->g1(), 4712 oop_closure->pss(), 4713 oop_closure->rp()), 4714 _klass_in_cld_closure(&_oop_in_klass_closure, only_young), 4715 _claim(claim) { 4716 4717 } 4718 4719 void do_cld(ClassLoaderData* cld) { 4720 cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim); 4721 } 4722 }; 4723 4724 class G1CodeBlobClosure: public CodeBlobClosure { 4725 OopClosure* _f; 4726 4727 public: 4728 G1CodeBlobClosure(OopClosure* f) : _f(f) {} 4729 void do_code_blob(CodeBlob* blob) { 4730 nmethod* that = blob->as_nmethod_or_null(); 4731 if (that != NULL) { 4732 if (!that->test_set_oops_do_mark()) { 4733 that->oops_do(_f); 4734 that->fix_oop_relocations(); 4735 } 4736 } 4737 } 4738 }; 4739 4740 void work(uint worker_id) { 4741 if (worker_id >= _n_workers) return; // no work needed this round 4742 4743 double start_time_ms = os::elapsedTime() * 1000.0; 4744 _g1h->g1_policy()->phase_times()->record_gc_worker_start_time(worker_id, start_time_ms); 4745 4746 { 4747 ResourceMark rm; 4748 HandleMark hm; 4749 4750 ReferenceProcessor* rp = _g1h->ref_processor_stw(); 4751 4752 G1ParScanThreadState pss(_g1h, worker_id, rp); 4753 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp); 4754 4755 pss.set_evac_failure_closure(&evac_failure_cl); 4756 4757 bool only_young = _g1h->g1_policy()->gcs_are_young(); 4758 4759 // Non-IM young GC. 4760 G1ParCopyClosure<G1BarrierNone, G1MarkNone> scan_only_root_cl(_g1h, &pss, rp); 4761 G1CLDClosure<G1MarkNone> scan_only_cld_cl(&scan_only_root_cl, 4762 only_young, // Only process dirty klasses. 4763 false); // No need to claim CLDs. 4764 // IM young GC. 4765 // Strong roots closures. 4766 G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot> scan_mark_root_cl(_g1h, &pss, rp); 4767 G1CLDClosure<G1MarkFromRoot> scan_mark_cld_cl(&scan_mark_root_cl, 4768 false, // Process all klasses. 4769 true); // Need to claim CLDs. 4770 // Weak roots closures. 4771 G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, &pss, rp); 4772 G1CLDClosure<G1MarkPromotedFromRoot> scan_mark_weak_cld_cl(&scan_mark_weak_root_cl, 4773 false, // Process all klasses. 4774 true); // Need to claim CLDs. 4775 4776 G1CodeBlobClosure scan_only_code_cl(&scan_only_root_cl); 4777 G1CodeBlobClosure scan_mark_code_cl(&scan_mark_root_cl); 4778 // IM Weak code roots are handled later. 4779 4780 OopClosure* strong_root_cl; 4781 OopClosure* weak_root_cl; 4782 CLDClosure* strong_cld_cl; 4783 CLDClosure* weak_cld_cl; 4784 CodeBlobClosure* strong_code_cl; 4785 4786 if (_g1h->g1_policy()->during_initial_mark_pause()) { 4787 // We also need to mark copied objects. 4788 strong_root_cl = &scan_mark_root_cl; 4789 strong_cld_cl = &scan_mark_cld_cl; 4790 strong_code_cl = &scan_mark_code_cl; 4791 if (ClassUnloadingWithConcurrentMark) { 4792 weak_root_cl = &scan_mark_weak_root_cl; 4793 weak_cld_cl = &scan_mark_weak_cld_cl; 4794 } else { 4795 weak_root_cl = &scan_mark_root_cl; 4796 weak_cld_cl = &scan_mark_cld_cl; 4797 } 4798 } else { 4799 strong_root_cl = &scan_only_root_cl; 4800 weak_root_cl = &scan_only_root_cl; 4801 strong_cld_cl = &scan_only_cld_cl; 4802 weak_cld_cl = &scan_only_cld_cl; 4803 strong_code_cl = &scan_only_code_cl; 4804 } 4805 4806 4807 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss); 4808 4809 pss.start_strong_roots(); 4810 _g1h->g1_process_roots(strong_root_cl, 4811 weak_root_cl, 4812 &push_heap_rs_cl, 4813 strong_cld_cl, 4814 weak_cld_cl, 4815 strong_code_cl, 4816 worker_id); 4817 4818 pss.end_strong_roots(); 4819 4820 { 4821 double start = os::elapsedTime(); 4822 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator); 4823 evac.do_void(); 4824 double elapsed_ms = (os::elapsedTime()-start)*1000.0; 4825 double term_ms = pss.term_time()*1000.0; 4826 _g1h->g1_policy()->phase_times()->add_obj_copy_time(worker_id, elapsed_ms-term_ms); 4827 _g1h->g1_policy()->phase_times()->record_termination(worker_id, term_ms, pss.term_attempts()); 4828 } 4829 _g1h->g1_policy()->record_thread_age_table(pss.age_table()); 4830 _g1h->update_surviving_young_words(pss.surviving_young_words()+1); 4831 4832 if (ParallelGCVerbose) { 4833 MutexLocker x(stats_lock()); 4834 pss.print_termination_stats(worker_id); 4835 } 4836 4837 assert(pss.queue_is_empty(), "should be empty"); 4838 4839 // Close the inner scope so that the ResourceMark and HandleMark 4840 // destructors are executed here and are included as part of the 4841 // "GC Worker Time". 4842 } 4843 4844 double end_time_ms = os::elapsedTime() * 1000.0; 4845 _g1h->g1_policy()->phase_times()->record_gc_worker_end_time(worker_id, end_time_ms); 4846 } 4847 }; 4848 4849 // *** Common G1 Evacuation Stuff 4850 4851 // This method is run in a GC worker. 4852 4853 void 4854 G1CollectedHeap:: 4855 g1_process_roots(OopClosure* scan_non_heap_roots, 4856 OopClosure* scan_non_heap_weak_roots, 4857 OopsInHeapRegionClosure* scan_rs, 4858 CLDClosure* scan_strong_clds, 4859 CLDClosure* scan_weak_clds, 4860 CodeBlobClosure* scan_strong_code, 4861 uint worker_i) { 4862 4863 // First scan the shared roots. 4864 double ext_roots_start = os::elapsedTime(); 4865 double closure_app_time_sec = 0.0; 4866 4867 bool during_im = _g1h->g1_policy()->during_initial_mark_pause(); 4868 bool trace_metadata = during_im && ClassUnloadingWithConcurrentMark; 4869 4870 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots); 4871 BufferingOopClosure buf_scan_non_heap_weak_roots(scan_non_heap_weak_roots); 4872 4873 process_roots(false, // no scoping; this is parallel code 4874 SharedHeap::SO_None, 4875 &buf_scan_non_heap_roots, 4876 &buf_scan_non_heap_weak_roots, 4877 scan_strong_clds, 4878 // Unloading Initial Marks handle the weak CLDs separately. 4879 (trace_metadata ? NULL : scan_weak_clds), 4880 scan_strong_code); 4881 4882 // Now the CM ref_processor roots. 4883 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) { 4884 // We need to treat the discovered reference lists of the 4885 // concurrent mark ref processor as roots and keep entries 4886 // (which are added by the marking threads) on them live 4887 // until they can be processed at the end of marking. 4888 ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots); 4889 } 4890 4891 if (trace_metadata) { 4892 // Barrier to make sure all workers passed 4893 // the strong CLD and strong nmethods phases. 4894 active_strong_roots_scope()->wait_until_all_workers_done_with_threads(n_par_threads()); 4895 4896 // Now take the complement of the strong CLDs. 4897 ClassLoaderDataGraph::roots_cld_do(NULL, scan_weak_clds); 4898 } 4899 4900 // Finish up any enqueued closure apps (attributed as object copy time). 4901 buf_scan_non_heap_roots.done(); 4902 buf_scan_non_heap_weak_roots.done(); 4903 4904 double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds() 4905 + buf_scan_non_heap_weak_roots.closure_app_seconds(); 4906 4907 g1_policy()->phase_times()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0); 4908 4909 double ext_root_time_ms = 4910 ((os::elapsedTime() - ext_roots_start) - obj_copy_time_sec) * 1000.0; 4911 4912 g1_policy()->phase_times()->record_ext_root_scan_time(worker_i, ext_root_time_ms); 4913 4914 // During conc marking we have to filter the per-thread SATB buffers 4915 // to make sure we remove any oops into the CSet (which will show up 4916 // as implicitly live). 4917 double satb_filtering_ms = 0.0; 4918 if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers)) { 4919 if (mark_in_progress()) { 4920 double satb_filter_start = os::elapsedTime(); 4921 4922 JavaThread::satb_mark_queue_set().filter_thread_buffers(); 4923 4924 satb_filtering_ms = (os::elapsedTime() - satb_filter_start) * 1000.0; 4925 } 4926 } 4927 g1_policy()->phase_times()->record_satb_filtering_time(worker_i, satb_filtering_ms); 4928 4929 // Now scan the complement of the collection set. 4930 MarkingCodeBlobClosure scavenge_cs_nmethods(scan_non_heap_weak_roots, CodeBlobToOopClosure::FixRelocations); 4931 4932 g1_rem_set()->oops_into_collection_set_do(scan_rs, &scavenge_cs_nmethods, worker_i); 4933 4934 _process_strong_tasks->all_tasks_completed(); 4935 } 4936 4937 class G1StringSymbolTableUnlinkTask : public AbstractGangTask { 4938 private: 4939 BoolObjectClosure* _is_alive; 4940 int _initial_string_table_size; 4941 int _initial_symbol_table_size; 4942 4943 bool _process_strings; 4944 int _strings_processed; 4945 int _strings_removed; 4946 4947 bool _process_symbols; 4948 int _symbols_processed; 4949 int _symbols_removed; 4950 4951 bool _do_in_parallel; 4952 public: 4953 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) : 4954 AbstractGangTask("String/Symbol Unlinking"), 4955 _is_alive(is_alive), 4956 _do_in_parallel(G1CollectedHeap::use_parallel_gc_threads()), 4957 _process_strings(process_strings), _strings_processed(0), _strings_removed(0), 4958 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) { 4959 4960 _initial_string_table_size = StringTable::the_table()->table_size(); 4961 _initial_symbol_table_size = SymbolTable::the_table()->table_size(); 4962 if (process_strings) { 4963 StringTable::clear_parallel_claimed_index(); 4964 } 4965 if (process_symbols) { 4966 SymbolTable::clear_parallel_claimed_index(); 4967 } 4968 } 4969 4970 ~G1StringSymbolTableUnlinkTask() { 4971 guarantee(!_process_strings || !_do_in_parallel || StringTable::parallel_claimed_index() >= _initial_string_table_size, 4972 err_msg("claim value "INT32_FORMAT" after unlink less than initial string table size "INT32_FORMAT, 4973 StringTable::parallel_claimed_index(), _initial_string_table_size)); 4974 guarantee(!_process_symbols || !_do_in_parallel || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size, 4975 err_msg("claim value "INT32_FORMAT" after unlink less than initial symbol table size "INT32_FORMAT, 4976 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size)); 4977 4978 if (G1TraceStringSymbolTableScrubbing) { 4979 gclog_or_tty->print_cr("Cleaned string and symbol table, " 4980 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, " 4981 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed", 4982 strings_processed(), strings_removed(), 4983 symbols_processed(), symbols_removed()); 4984 } 4985 } 4986 4987 void work(uint worker_id) { 4988 if (_do_in_parallel) { 4989 int strings_processed = 0; 4990 int strings_removed = 0; 4991 int symbols_processed = 0; 4992 int symbols_removed = 0; 4993 if (_process_strings) { 4994 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed); 4995 Atomic::add(strings_processed, &_strings_processed); 4996 Atomic::add(strings_removed, &_strings_removed); 4997 } 4998 if (_process_symbols) { 4999 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed); 5000 Atomic::add(symbols_processed, &_symbols_processed); 5001 Atomic::add(symbols_removed, &_symbols_removed); 5002 } 5003 } else { 5004 if (_process_strings) { 5005 StringTable::unlink(_is_alive, &_strings_processed, &_strings_removed); 5006 } 5007 if (_process_symbols) { 5008 SymbolTable::unlink(&_symbols_processed, &_symbols_removed); 5009 } 5010 } 5011 } 5012 5013 size_t strings_processed() const { return (size_t)_strings_processed; } 5014 size_t strings_removed() const { return (size_t)_strings_removed; } 5015 5016 size_t symbols_processed() const { return (size_t)_symbols_processed; } 5017 size_t symbols_removed() const { return (size_t)_symbols_removed; } 5018 }; 5019 5020 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC { 5021 private: 5022 static Monitor* _lock; 5023 5024 BoolObjectClosure* const _is_alive; 5025 const bool _unloading_occurred; 5026 const uint _num_workers; 5027 5028 // Variables used to claim nmethods. 5029 nmethod* _first_nmethod; 5030 volatile nmethod* _claimed_nmethod; 5031 5032 // The list of nmethods that need to be processed by the second pass. 5033 volatile nmethod* _postponed_list; 5034 volatile uint _num_entered_barrier; 5035 5036 public: 5037 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) : 5038 _is_alive(is_alive), 5039 _unloading_occurred(unloading_occurred), 5040 _num_workers(num_workers), 5041 _first_nmethod(NULL), 5042 _claimed_nmethod(NULL), 5043 _postponed_list(NULL), 5044 _num_entered_barrier(0) 5045 { 5046 nmethod::increase_unloading_clock(); 5047 _first_nmethod = CodeCache::alive_nmethod(CodeCache::first()); 5048 _claimed_nmethod = (volatile nmethod*)_first_nmethod; 5049 } 5050 5051 ~G1CodeCacheUnloadingTask() { 5052 CodeCache::verify_clean_inline_caches(); 5053 5054 CodeCache::set_needs_cache_clean(false); 5055 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be"); 5056 5057 CodeCache::verify_icholder_relocations(); 5058 } 5059 5060 private: 5061 void add_to_postponed_list(nmethod* nm) { 5062 nmethod* old; 5063 do { 5064 old = (nmethod*)_postponed_list; 5065 nm->set_unloading_next(old); 5066 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old); 5067 } 5068 5069 void clean_nmethod(nmethod* nm) { 5070 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred); 5071 5072 if (postponed) { 5073 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet. 5074 add_to_postponed_list(nm); 5075 } 5076 5077 // Mark that this thread has been cleaned/unloaded. 5078 // After this call, it will be safe to ask if this nmethod was unloaded or not. 5079 nm->set_unloading_clock(nmethod::global_unloading_clock()); 5080 } 5081 5082 void clean_nmethod_postponed(nmethod* nm) { 5083 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred); 5084 } 5085 5086 static const int MaxClaimNmethods = 16; 5087 5088 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) { 5089 nmethod* first; 5090 nmethod* last; 5091 5092 do { 5093 *num_claimed_nmethods = 0; 5094 5095 first = last = (nmethod*)_claimed_nmethod; 5096 5097 if (first != NULL) { 5098 for (int i = 0; i < MaxClaimNmethods; i++) { 5099 last = CodeCache::alive_nmethod(CodeCache::next(last)); 5100 5101 if (last == NULL) { 5102 break; 5103 } 5104 5105 claimed_nmethods[i] = last; 5106 (*num_claimed_nmethods)++; 5107 } 5108 } 5109 5110 } while ((nmethod*)Atomic::cmpxchg_ptr(last, &_claimed_nmethod, first) != first); 5111 } 5112 5113 nmethod* claim_postponed_nmethod() { 5114 nmethod* claim; 5115 nmethod* next; 5116 5117 do { 5118 claim = (nmethod*)_postponed_list; 5119 if (claim == NULL) { 5120 return NULL; 5121 } 5122 5123 next = claim->unloading_next(); 5124 5125 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim); 5126 5127 return claim; 5128 } 5129 5130 public: 5131 // Mark that we're done with the first pass of nmethod cleaning. 5132 void barrier_mark(uint worker_id) { 5133 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 5134 _num_entered_barrier++; 5135 if (_num_entered_barrier == _num_workers) { 5136 ml.notify_all(); 5137 } 5138 } 5139 5140 // See if we have to wait for the other workers to 5141 // finish their first-pass nmethod cleaning work. 5142 void barrier_wait(uint worker_id) { 5143 if (_num_entered_barrier < _num_workers) { 5144 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 5145 while (_num_entered_barrier < _num_workers) { 5146 ml.wait(Mutex::_no_safepoint_check_flag, 0, false); 5147 } 5148 } 5149 } 5150 5151 // Cleaning and unloading of nmethods. Some work has to be postponed 5152 // to the second pass, when we know which nmethods survive. 5153 void work_first_pass(uint worker_id) { 5154 // The first nmethods is claimed by the first worker. 5155 if (worker_id == 0 && _first_nmethod != NULL) { 5156 clean_nmethod(_first_nmethod); 5157 _first_nmethod = NULL; 5158 } 5159 5160 int num_claimed_nmethods; 5161 nmethod* claimed_nmethods[MaxClaimNmethods]; 5162 5163 while (true) { 5164 claim_nmethods(claimed_nmethods, &num_claimed_nmethods); 5165 5166 if (num_claimed_nmethods == 0) { 5167 break; 5168 } 5169 5170 for (int i = 0; i < num_claimed_nmethods; i++) { 5171 clean_nmethod(claimed_nmethods[i]); 5172 } 5173 } 5174 } 5175 5176 void work_second_pass(uint worker_id) { 5177 nmethod* nm; 5178 // Take care of postponed nmethods. 5179 while ((nm = claim_postponed_nmethod()) != NULL) { 5180 clean_nmethod_postponed(nm); 5181 } 5182 } 5183 }; 5184 5185 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock"); 5186 5187 class G1KlassCleaningTask : public StackObj { 5188 BoolObjectClosure* _is_alive; 5189 volatile jint _clean_klass_tree_claimed; 5190 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator; 5191 5192 public: 5193 G1KlassCleaningTask(BoolObjectClosure* is_alive) : 5194 _is_alive(is_alive), 5195 _clean_klass_tree_claimed(0), 5196 _klass_iterator() { 5197 } 5198 5199 private: 5200 bool claim_clean_klass_tree_task() { 5201 if (_clean_klass_tree_claimed) { 5202 return false; 5203 } 5204 5205 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0; 5206 } 5207 5208 InstanceKlass* claim_next_klass() { 5209 Klass* klass; 5210 do { 5211 klass =_klass_iterator.next_klass(); 5212 } while (klass != NULL && !klass->oop_is_instance()); 5213 5214 return (InstanceKlass*)klass; 5215 } 5216 5217 public: 5218 5219 void clean_klass(InstanceKlass* ik) { 5220 ik->clean_implementors_list(_is_alive); 5221 ik->clean_method_data(_is_alive); 5222 5223 // G1 specific cleanup work that has 5224 // been moved here to be done in parallel. 5225 ik->clean_dependent_nmethods(); 5226 } 5227 5228 void work() { 5229 ResourceMark rm; 5230 5231 // One worker will clean the subklass/sibling klass tree. 5232 if (claim_clean_klass_tree_task()) { 5233 Klass::clean_subklass_tree(_is_alive); 5234 } 5235 5236 // All workers will help cleaning the classes, 5237 InstanceKlass* klass; 5238 while ((klass = claim_next_klass()) != NULL) { 5239 clean_klass(klass); 5240 } 5241 } 5242 }; 5243 5244 // To minimize the remark pause times, the tasks below are done in parallel. 5245 class G1ParallelCleaningTask : public AbstractGangTask { 5246 private: 5247 G1StringSymbolTableUnlinkTask _string_symbol_task; 5248 G1CodeCacheUnloadingTask _code_cache_task; 5249 G1KlassCleaningTask _klass_cleaning_task; 5250 5251 public: 5252 // The constructor is run in the VMThread. 5253 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) : 5254 AbstractGangTask("Parallel Cleaning"), 5255 _string_symbol_task(is_alive, process_strings, process_symbols), 5256 _code_cache_task(num_workers, is_alive, unloading_occurred), 5257 _klass_cleaning_task(is_alive) { 5258 } 5259 5260 // The parallel work done by all worker threads. 5261 void work(uint worker_id) { 5262 // Do first pass of code cache cleaning. 5263 _code_cache_task.work_first_pass(worker_id); 5264 5265 // Let the threads mark that the first pass is done. 5266 _code_cache_task.barrier_mark(worker_id); 5267 5268 // Clean the Strings and Symbols. 5269 _string_symbol_task.work(worker_id); 5270 5271 // Wait for all workers to finish the first code cache cleaning pass. 5272 _code_cache_task.barrier_wait(worker_id); 5273 5274 // Do the second code cache cleaning work, which realize on 5275 // the liveness information gathered during the first pass. 5276 _code_cache_task.work_second_pass(worker_id); 5277 5278 // Clean all klasses that were not unloaded. 5279 _klass_cleaning_task.work(); 5280 } 5281 }; 5282 5283 5284 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive, 5285 bool process_strings, 5286 bool process_symbols, 5287 bool class_unloading_occurred) { 5288 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ? 5289 workers()->active_workers() : 1); 5290 5291 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, 5292 n_workers, class_unloading_occurred); 5293 if (G1CollectedHeap::use_parallel_gc_threads()) { 5294 set_par_threads(n_workers); 5295 workers()->run_task(&g1_unlink_task); 5296 set_par_threads(0); 5297 } else { 5298 g1_unlink_task.work(0); 5299 } 5300 } 5301 5302 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive, 5303 bool process_strings, bool process_symbols) { 5304 { 5305 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ? 5306 _g1h->workers()->active_workers() : 1); 5307 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols); 5308 if (G1CollectedHeap::use_parallel_gc_threads()) { 5309 set_par_threads(n_workers); 5310 workers()->run_task(&g1_unlink_task); 5311 set_par_threads(0); 5312 } else { 5313 g1_unlink_task.work(0); 5314 } 5315 } 5316 5317 if (G1StringDedup::is_enabled()) { 5318 G1StringDedup::unlink(is_alive); 5319 } 5320 } 5321 5322 class G1RedirtyLoggedCardsTask : public AbstractGangTask { 5323 private: 5324 DirtyCardQueueSet* _queue; 5325 public: 5326 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { } 5327 5328 virtual void work(uint worker_id) { 5329 double start_time = os::elapsedTime(); 5330 5331 RedirtyLoggedCardTableEntryClosure cl; 5332 if (G1CollectedHeap::heap()->use_parallel_gc_threads()) { 5333 _queue->par_apply_closure_to_all_completed_buffers(&cl); 5334 } else { 5335 _queue->apply_closure_to_all_completed_buffers(&cl); 5336 } 5337 5338 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times(); 5339 timer->record_redirty_logged_cards_time_ms(worker_id, (os::elapsedTime() - start_time) * 1000.0); 5340 timer->record_redirty_logged_cards_processed_cards(worker_id, cl.num_processed()); 5341 } 5342 }; 5343 5344 void G1CollectedHeap::redirty_logged_cards() { 5345 guarantee(G1DeferredRSUpdate, "Must only be called when using deferred RS updates."); 5346 double redirty_logged_cards_start = os::elapsedTime(); 5347 5348 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ? 5349 _g1h->workers()->active_workers() : 1); 5350 5351 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set()); 5352 dirty_card_queue_set().reset_for_par_iteration(); 5353 if (use_parallel_gc_threads()) { 5354 set_par_threads(n_workers); 5355 workers()->run_task(&redirty_task); 5356 set_par_threads(0); 5357 } else { 5358 redirty_task.work(0); 5359 } 5360 5361 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set(); 5362 dcq.merge_bufferlists(&dirty_card_queue_set()); 5363 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed"); 5364 5365 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0); 5366 } 5367 5368 // Weak Reference Processing support 5369 5370 // An always "is_alive" closure that is used to preserve referents. 5371 // If the object is non-null then it's alive. Used in the preservation 5372 // of referent objects that are pointed to by reference objects 5373 // discovered by the CM ref processor. 5374 class G1AlwaysAliveClosure: public BoolObjectClosure { 5375 G1CollectedHeap* _g1; 5376 public: 5377 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 5378 bool do_object_b(oop p) { 5379 if (p != NULL) { 5380 return true; 5381 } 5382 return false; 5383 } 5384 }; 5385 5386 bool G1STWIsAliveClosure::do_object_b(oop p) { 5387 // An object is reachable if it is outside the collection set, 5388 // or is inside and copied. 5389 return !_g1->obj_in_cs(p) || p->is_forwarded(); 5390 } 5391 5392 // Non Copying Keep Alive closure 5393 class G1KeepAliveClosure: public OopClosure { 5394 G1CollectedHeap* _g1; 5395 public: 5396 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 5397 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } 5398 void do_oop(oop* p) { 5399 oop obj = *p; 5400 5401 G1CollectedHeap::in_cset_state_t cset_state = _g1->in_cset_state(obj); 5402 if (obj == NULL || cset_state == G1CollectedHeap::InNeither) { 5403 return; 5404 } 5405 if (cset_state == G1CollectedHeap::InCSet) { 5406 assert( obj->is_forwarded(), "invariant" ); 5407 *p = obj->forwardee(); 5408 } else { 5409 assert(!obj->is_forwarded(), "invariant" ); 5410 assert(cset_state == G1CollectedHeap::IsHumongous, 5411 err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state)); 5412 _g1->set_humongous_is_live(obj); 5413 } 5414 } 5415 }; 5416 5417 // Copying Keep Alive closure - can be called from both 5418 // serial and parallel code as long as different worker 5419 // threads utilize different G1ParScanThreadState instances 5420 // and different queues. 5421 5422 class G1CopyingKeepAliveClosure: public OopClosure { 5423 G1CollectedHeap* _g1h; 5424 OopClosure* _copy_non_heap_obj_cl; 5425 G1ParScanThreadState* _par_scan_state; 5426 5427 public: 5428 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, 5429 OopClosure* non_heap_obj_cl, 5430 G1ParScanThreadState* pss): 5431 _g1h(g1h), 5432 _copy_non_heap_obj_cl(non_heap_obj_cl), 5433 _par_scan_state(pss) 5434 {} 5435 5436 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 5437 virtual void do_oop( oop* p) { do_oop_work(p); } 5438 5439 template <class T> void do_oop_work(T* p) { 5440 oop obj = oopDesc::load_decode_heap_oop(p); 5441 5442 if (_g1h->is_in_cset_or_humongous(obj)) { 5443 // If the referent object has been forwarded (either copied 5444 // to a new location or to itself in the event of an 5445 // evacuation failure) then we need to update the reference 5446 // field and, if both reference and referent are in the G1 5447 // heap, update the RSet for the referent. 5448 // 5449 // If the referent has not been forwarded then we have to keep 5450 // it alive by policy. Therefore we have copy the referent. 5451 // 5452 // If the reference field is in the G1 heap then we can push 5453 // on the PSS queue. When the queue is drained (after each 5454 // phase of reference processing) the object and it's followers 5455 // will be copied, the reference field set to point to the 5456 // new location, and the RSet updated. Otherwise we need to 5457 // use the the non-heap or metadata closures directly to copy 5458 // the referent object and update the pointer, while avoiding 5459 // updating the RSet. 5460 5461 if (_g1h->is_in_g1_reserved(p)) { 5462 _par_scan_state->push_on_queue(p); 5463 } else { 5464 assert(!Metaspace::contains((const void*)p), 5465 err_msg("Unexpectedly found a pointer from metadata: " 5466 PTR_FORMAT, p)); 5467 _copy_non_heap_obj_cl->do_oop(p); 5468 } 5469 } 5470 } 5471 }; 5472 5473 // Serial drain queue closure. Called as the 'complete_gc' 5474 // closure for each discovered list in some of the 5475 // reference processing phases. 5476 5477 class G1STWDrainQueueClosure: public VoidClosure { 5478 protected: 5479 G1CollectedHeap* _g1h; 5480 G1ParScanThreadState* _par_scan_state; 5481 5482 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 5483 5484 public: 5485 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : 5486 _g1h(g1h), 5487 _par_scan_state(pss) 5488 { } 5489 5490 void do_void() { 5491 G1ParScanThreadState* const pss = par_scan_state(); 5492 pss->trim_queue(); 5493 } 5494 }; 5495 5496 // Parallel Reference Processing closures 5497 5498 // Implementation of AbstractRefProcTaskExecutor for parallel reference 5499 // processing during G1 evacuation pauses. 5500 5501 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 5502 private: 5503 G1CollectedHeap* _g1h; 5504 RefToScanQueueSet* _queues; 5505 FlexibleWorkGang* _workers; 5506 int _active_workers; 5507 5508 public: 5509 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, 5510 FlexibleWorkGang* workers, 5511 RefToScanQueueSet *task_queues, 5512 int n_workers) : 5513 _g1h(g1h), 5514 _queues(task_queues), 5515 _workers(workers), 5516 _active_workers(n_workers) 5517 { 5518 assert(n_workers > 0, "shouldn't call this otherwise"); 5519 } 5520 5521 // Executes the given task using concurrent marking worker threads. 5522 virtual void execute(ProcessTask& task); 5523 virtual void execute(EnqueueTask& task); 5524 }; 5525 5526 // Gang task for possibly parallel reference processing 5527 5528 class G1STWRefProcTaskProxy: public AbstractGangTask { 5529 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 5530 ProcessTask& _proc_task; 5531 G1CollectedHeap* _g1h; 5532 RefToScanQueueSet *_task_queues; 5533 ParallelTaskTerminator* _terminator; 5534 5535 public: 5536 G1STWRefProcTaskProxy(ProcessTask& proc_task, 5537 G1CollectedHeap* g1h, 5538 RefToScanQueueSet *task_queues, 5539 ParallelTaskTerminator* terminator) : 5540 AbstractGangTask("Process reference objects in parallel"), 5541 _proc_task(proc_task), 5542 _g1h(g1h), 5543 _task_queues(task_queues), 5544 _terminator(terminator) 5545 {} 5546 5547 virtual void work(uint worker_id) { 5548 // The reference processing task executed by a single worker. 5549 ResourceMark rm; 5550 HandleMark hm; 5551 5552 G1STWIsAliveClosure is_alive(_g1h); 5553 5554 G1ParScanThreadState pss(_g1h, worker_id, NULL); 5555 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL); 5556 5557 pss.set_evac_failure_closure(&evac_failure_cl); 5558 5559 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL); 5560 5561 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL); 5562 5563 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5564 5565 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5566 // We also need to mark copied objects. 5567 copy_non_heap_cl = ©_mark_non_heap_cl; 5568 } 5569 5570 // Keep alive closure. 5571 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss); 5572 5573 // Complete GC closure 5574 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator); 5575 5576 // Call the reference processing task's work routine. 5577 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); 5578 5579 // Note we cannot assert that the refs array is empty here as not all 5580 // of the processing tasks (specifically phase2 - pp2_work) execute 5581 // the complete_gc closure (which ordinarily would drain the queue) so 5582 // the queue may not be empty. 5583 } 5584 }; 5585 5586 // Driver routine for parallel reference processing. 5587 // Creates an instance of the ref processing gang 5588 // task and has the worker threads execute it. 5589 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) { 5590 assert(_workers != NULL, "Need parallel worker threads."); 5591 5592 ParallelTaskTerminator terminator(_active_workers, _queues); 5593 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator); 5594 5595 _g1h->set_par_threads(_active_workers); 5596 _workers->run_task(&proc_task_proxy); 5597 _g1h->set_par_threads(0); 5598 } 5599 5600 // Gang task for parallel reference enqueueing. 5601 5602 class G1STWRefEnqueueTaskProxy: public AbstractGangTask { 5603 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; 5604 EnqueueTask& _enq_task; 5605 5606 public: 5607 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) : 5608 AbstractGangTask("Enqueue reference objects in parallel"), 5609 _enq_task(enq_task) 5610 { } 5611 5612 virtual void work(uint worker_id) { 5613 _enq_task.work(worker_id); 5614 } 5615 }; 5616 5617 // Driver routine for parallel reference enqueueing. 5618 // Creates an instance of the ref enqueueing gang 5619 // task and has the worker threads execute it. 5620 5621 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) { 5622 assert(_workers != NULL, "Need parallel worker threads."); 5623 5624 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task); 5625 5626 _g1h->set_par_threads(_active_workers); 5627 _workers->run_task(&enq_task_proxy); 5628 _g1h->set_par_threads(0); 5629 } 5630 5631 // End of weak reference support closures 5632 5633 // Abstract task used to preserve (i.e. copy) any referent objects 5634 // that are in the collection set and are pointed to by reference 5635 // objects discovered by the CM ref processor. 5636 5637 class G1ParPreserveCMReferentsTask: public AbstractGangTask { 5638 protected: 5639 G1CollectedHeap* _g1h; 5640 RefToScanQueueSet *_queues; 5641 ParallelTaskTerminator _terminator; 5642 uint _n_workers; 5643 5644 public: 5645 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) : 5646 AbstractGangTask("ParPreserveCMReferents"), 5647 _g1h(g1h), 5648 _queues(task_queues), 5649 _terminator(workers, _queues), 5650 _n_workers(workers) 5651 { } 5652 5653 void work(uint worker_id) { 5654 ResourceMark rm; 5655 HandleMark hm; 5656 5657 G1ParScanThreadState pss(_g1h, worker_id, NULL); 5658 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL); 5659 5660 pss.set_evac_failure_closure(&evac_failure_cl); 5661 5662 assert(pss.queue_is_empty(), "both queue and overflow should be empty"); 5663 5664 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL); 5665 5666 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL); 5667 5668 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5669 5670 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5671 // We also need to mark copied objects. 5672 copy_non_heap_cl = ©_mark_non_heap_cl; 5673 } 5674 5675 // Is alive closure 5676 G1AlwaysAliveClosure always_alive(_g1h); 5677 5678 // Copying keep alive closure. Applied to referent objects that need 5679 // to be copied. 5680 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss); 5681 5682 ReferenceProcessor* rp = _g1h->ref_processor_cm(); 5683 5684 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q(); 5685 uint stride = MIN2(MAX2(_n_workers, 1U), limit); 5686 5687 // limit is set using max_num_q() - which was set using ParallelGCThreads. 5688 // So this must be true - but assert just in case someone decides to 5689 // change the worker ids. 5690 assert(0 <= worker_id && worker_id < limit, "sanity"); 5691 assert(!rp->discovery_is_atomic(), "check this code"); 5692 5693 // Select discovered lists [i, i+stride, i+2*stride,...,limit) 5694 for (uint idx = worker_id; idx < limit; idx += stride) { 5695 DiscoveredList& ref_list = rp->discovered_refs()[idx]; 5696 5697 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive); 5698 while (iter.has_next()) { 5699 // Since discovery is not atomic for the CM ref processor, we 5700 // can see some null referent objects. 5701 iter.load_ptrs(DEBUG_ONLY(true)); 5702 oop ref = iter.obj(); 5703 5704 // This will filter nulls. 5705 if (iter.is_referent_alive()) { 5706 iter.make_referent_alive(); 5707 } 5708 iter.move_to_next(); 5709 } 5710 } 5711 5712 // Drain the queue - which may cause stealing 5713 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator); 5714 drain_queue.do_void(); 5715 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure 5716 assert(pss.queue_is_empty(), "should be"); 5717 } 5718 }; 5719 5720 // Weak Reference processing during an evacuation pause (part 1). 5721 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) { 5722 double ref_proc_start = os::elapsedTime(); 5723 5724 ReferenceProcessor* rp = _ref_processor_stw; 5725 assert(rp->discovery_enabled(), "should have been enabled"); 5726 5727 // Any reference objects, in the collection set, that were 'discovered' 5728 // by the CM ref processor should have already been copied (either by 5729 // applying the external root copy closure to the discovered lists, or 5730 // by following an RSet entry). 5731 // 5732 // But some of the referents, that are in the collection set, that these 5733 // reference objects point to may not have been copied: the STW ref 5734 // processor would have seen that the reference object had already 5735 // been 'discovered' and would have skipped discovering the reference, 5736 // but would not have treated the reference object as a regular oop. 5737 // As a result the copy closure would not have been applied to the 5738 // referent object. 5739 // 5740 // We need to explicitly copy these referent objects - the references 5741 // will be processed at the end of remarking. 5742 // 5743 // We also need to do this copying before we process the reference 5744 // objects discovered by the STW ref processor in case one of these 5745 // referents points to another object which is also referenced by an 5746 // object discovered by the STW ref processor. 5747 5748 assert(!G1CollectedHeap::use_parallel_gc_threads() || 5749 no_of_gc_workers == workers()->active_workers(), 5750 "Need to reset active GC workers"); 5751 5752 set_par_threads(no_of_gc_workers); 5753 G1ParPreserveCMReferentsTask keep_cm_referents(this, 5754 no_of_gc_workers, 5755 _task_queues); 5756 5757 if (G1CollectedHeap::use_parallel_gc_threads()) { 5758 workers()->run_task(&keep_cm_referents); 5759 } else { 5760 keep_cm_referents.work(0); 5761 } 5762 5763 set_par_threads(0); 5764 5765 // Closure to test whether a referent is alive. 5766 G1STWIsAliveClosure is_alive(this); 5767 5768 // Even when parallel reference processing is enabled, the processing 5769 // of JNI refs is serial and performed serially by the current thread 5770 // rather than by a worker. The following PSS will be used for processing 5771 // JNI refs. 5772 5773 // Use only a single queue for this PSS. 5774 G1ParScanThreadState pss(this, 0, NULL); 5775 5776 // We do not embed a reference processor in the copying/scanning 5777 // closures while we're actually processing the discovered 5778 // reference objects. 5779 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL); 5780 5781 pss.set_evac_failure_closure(&evac_failure_cl); 5782 5783 assert(pss.queue_is_empty(), "pre-condition"); 5784 5785 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL); 5786 5787 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL); 5788 5789 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5790 5791 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5792 // We also need to mark copied objects. 5793 copy_non_heap_cl = ©_mark_non_heap_cl; 5794 } 5795 5796 // Keep alive closure. 5797 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, &pss); 5798 5799 // Serial Complete GC closure 5800 G1STWDrainQueueClosure drain_queue(this, &pss); 5801 5802 // Setup the soft refs policy... 5803 rp->setup_policy(false); 5804 5805 ReferenceProcessorStats stats; 5806 if (!rp->processing_is_mt()) { 5807 // Serial reference processing... 5808 stats = rp->process_discovered_references(&is_alive, 5809 &keep_alive, 5810 &drain_queue, 5811 NULL, 5812 _gc_timer_stw, 5813 _gc_tracer_stw->gc_id()); 5814 } else { 5815 // Parallel reference processing 5816 assert(rp->num_q() == no_of_gc_workers, "sanity"); 5817 assert(no_of_gc_workers <= rp->max_num_q(), "sanity"); 5818 5819 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers); 5820 stats = rp->process_discovered_references(&is_alive, 5821 &keep_alive, 5822 &drain_queue, 5823 &par_task_executor, 5824 _gc_timer_stw, 5825 _gc_tracer_stw->gc_id()); 5826 } 5827 5828 _gc_tracer_stw->report_gc_reference_stats(stats); 5829 5830 // We have completed copying any necessary live referent objects. 5831 assert(pss.queue_is_empty(), "both queue and overflow should be empty"); 5832 5833 double ref_proc_time = os::elapsedTime() - ref_proc_start; 5834 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 5835 } 5836 5837 // Weak Reference processing during an evacuation pause (part 2). 5838 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) { 5839 double ref_enq_start = os::elapsedTime(); 5840 5841 ReferenceProcessor* rp = _ref_processor_stw; 5842 assert(!rp->discovery_enabled(), "should have been disabled as part of processing"); 5843 5844 // Now enqueue any remaining on the discovered lists on to 5845 // the pending list. 5846 if (!rp->processing_is_mt()) { 5847 // Serial reference processing... 5848 rp->enqueue_discovered_references(); 5849 } else { 5850 // Parallel reference enqueueing 5851 5852 assert(no_of_gc_workers == workers()->active_workers(), 5853 "Need to reset active workers"); 5854 assert(rp->num_q() == no_of_gc_workers, "sanity"); 5855 assert(no_of_gc_workers <= rp->max_num_q(), "sanity"); 5856 5857 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers); 5858 rp->enqueue_discovered_references(&par_task_executor); 5859 } 5860 5861 rp->verify_no_references_recorded(); 5862 assert(!rp->discovery_enabled(), "should have been disabled"); 5863 5864 // FIXME 5865 // CM's reference processing also cleans up the string and symbol tables. 5866 // Should we do that here also? We could, but it is a serial operation 5867 // and could significantly increase the pause time. 5868 5869 double ref_enq_time = os::elapsedTime() - ref_enq_start; 5870 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0); 5871 } 5872 5873 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) { 5874 _expand_heap_after_alloc_failure = true; 5875 _evacuation_failed = false; 5876 5877 // Should G1EvacuationFailureALot be in effect for this GC? 5878 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) 5879 5880 g1_rem_set()->prepare_for_oops_into_collection_set_do(); 5881 5882 // Disable the hot card cache. 5883 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 5884 hot_card_cache->reset_hot_cache_claimed_index(); 5885 hot_card_cache->set_use_cache(false); 5886 5887 uint n_workers; 5888 if (G1CollectedHeap::use_parallel_gc_threads()) { 5889 n_workers = 5890 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 5891 workers()->active_workers(), 5892 Threads::number_of_non_daemon_threads()); 5893 assert(UseDynamicNumberOfGCThreads || 5894 n_workers == workers()->total_workers(), 5895 "If not dynamic should be using all the workers"); 5896 workers()->set_active_workers(n_workers); 5897 set_par_threads(n_workers); 5898 } else { 5899 assert(n_par_threads() == 0, 5900 "Should be the original non-parallel value"); 5901 n_workers = 1; 5902 } 5903 5904 G1ParTask g1_par_task(this, _task_queues); 5905 5906 init_for_evac_failure(NULL); 5907 5908 rem_set()->prepare_for_younger_refs_iterate(true); 5909 5910 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty"); 5911 double start_par_time_sec = os::elapsedTime(); 5912 double end_par_time_sec; 5913 5914 { 5915 StrongRootsScope srs(this); 5916 // InitialMark needs claim bits to keep track of the marked-through CLDs. 5917 if (g1_policy()->during_initial_mark_pause()) { 5918 ClassLoaderDataGraph::clear_claimed_marks(); 5919 } 5920 5921 if (G1CollectedHeap::use_parallel_gc_threads()) { 5922 // The individual threads will set their evac-failure closures. 5923 if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr(); 5924 // These tasks use ShareHeap::_process_strong_tasks 5925 assert(UseDynamicNumberOfGCThreads || 5926 workers()->active_workers() == workers()->total_workers(), 5927 "If not dynamic should be using all the workers"); 5928 workers()->run_task(&g1_par_task); 5929 } else { 5930 g1_par_task.set_for_termination(n_workers); 5931 g1_par_task.work(0); 5932 } 5933 end_par_time_sec = os::elapsedTime(); 5934 5935 // Closing the inner scope will execute the destructor 5936 // for the StrongRootsScope object. We record the current 5937 // elapsed time before closing the scope so that time 5938 // taken for the SRS destructor is NOT included in the 5939 // reported parallel time. 5940 } 5941 5942 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0; 5943 g1_policy()->phase_times()->record_par_time(par_time_ms); 5944 5945 double code_root_fixup_time_ms = 5946 (os::elapsedTime() - end_par_time_sec) * 1000.0; 5947 g1_policy()->phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms); 5948 5949 set_par_threads(0); 5950 5951 // Process any discovered reference objects - we have 5952 // to do this _before_ we retire the GC alloc regions 5953 // as we may have to copy some 'reachable' referent 5954 // objects (and their reachable sub-graphs) that were 5955 // not copied during the pause. 5956 process_discovered_references(n_workers); 5957 5958 // Weak root processing. 5959 { 5960 G1STWIsAliveClosure is_alive(this); 5961 G1KeepAliveClosure keep_alive(this); 5962 JNIHandles::weak_oops_do(&is_alive, &keep_alive); 5963 if (G1StringDedup::is_enabled()) { 5964 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive); 5965 } 5966 } 5967 5968 release_gc_alloc_regions(n_workers, evacuation_info); 5969 g1_rem_set()->cleanup_after_oops_into_collection_set_do(); 5970 5971 // Reset and re-enable the hot card cache. 5972 // Note the counts for the cards in the regions in the 5973 // collection set are reset when the collection set is freed. 5974 hot_card_cache->reset_hot_cache(); 5975 hot_card_cache->set_use_cache(true); 5976 5977 // Migrate the strong code roots attached to each region in 5978 // the collection set. Ideally we would like to do this 5979 // after we have finished the scanning/evacuation of the 5980 // strong code roots for a particular heap region. 5981 migrate_strong_code_roots(); 5982 5983 purge_code_root_memory(); 5984 5985 if (g1_policy()->during_initial_mark_pause()) { 5986 // Reset the claim values set during marking the strong code roots 5987 reset_heap_region_claim_values(); 5988 } 5989 5990 finalize_for_evac_failure(); 5991 5992 if (evacuation_failed()) { 5993 remove_self_forwarding_pointers(); 5994 5995 // Reset the G1EvacuationFailureALot counters and flags 5996 // Note: the values are reset only when an actual 5997 // evacuation failure occurs. 5998 NOT_PRODUCT(reset_evacuation_should_fail();) 5999 } 6000 6001 // Enqueue any remaining references remaining on the STW 6002 // reference processor's discovered lists. We need to do 6003 // this after the card table is cleaned (and verified) as 6004 // the act of enqueueing entries on to the pending list 6005 // will log these updates (and dirty their associated 6006 // cards). We need these updates logged to update any 6007 // RSets. 6008 enqueue_discovered_references(n_workers); 6009 6010 if (G1DeferredRSUpdate) { 6011 redirty_logged_cards(); 6012 } 6013 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 6014 } 6015 6016 void G1CollectedHeap::free_region(HeapRegion* hr, 6017 FreeRegionList* free_list, 6018 bool par, 6019 bool locked) { 6020 assert(!hr->isHumongous(), "this is only for non-humongous regions"); 6021 assert(!hr->is_empty(), "the region should not be empty"); 6022 assert(_hrs.is_available(hr->hrs_index()), "region should be committed"); 6023 assert(free_list != NULL, "pre-condition"); 6024 6025 if (G1VerifyBitmaps) { 6026 MemRegion mr(hr->bottom(), hr->end()); 6027 concurrent_mark()->clearRangePrevBitmap(mr); 6028 } 6029 6030 // Clear the card counts for this region. 6031 // Note: we only need to do this if the region is not young 6032 // (since we don't refine cards in young regions). 6033 if (!hr->is_young()) { 6034 _cg1r->hot_card_cache()->reset_card_counts(hr); 6035 } 6036 hr->hr_clear(par, true /* clear_space */, locked /* locked */); 6037 free_list->add_ordered(hr); 6038 } 6039 6040 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 6041 FreeRegionList* free_list, 6042 bool par) { 6043 assert(hr->startsHumongous(), "this is only for starts humongous regions"); 6044 assert(free_list != NULL, "pre-condition"); 6045 6046 size_t hr_capacity = hr->capacity(); 6047 // We need to read this before we make the region non-humongous, 6048 // otherwise the information will be gone. 6049 uint last_index = hr->last_hc_index(); 6050 hr->set_notHumongous(); 6051 free_region(hr, free_list, par); 6052 6053 uint i = hr->hrs_index() + 1; 6054 while (i < last_index) { 6055 HeapRegion* curr_hr = region_at(i); 6056 assert(curr_hr->continuesHumongous(), "invariant"); 6057 curr_hr->set_notHumongous(); 6058 free_region(curr_hr, free_list, par); 6059 i += 1; 6060 } 6061 } 6062 6063 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed, 6064 const HeapRegionSetCount& humongous_regions_removed) { 6065 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) { 6066 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 6067 _old_set.bulk_remove(old_regions_removed); 6068 _humongous_set.bulk_remove(humongous_regions_removed); 6069 } 6070 6071 } 6072 6073 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) { 6074 assert(list != NULL, "list can't be null"); 6075 if (!list->is_empty()) { 6076 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag); 6077 _hrs.insert_list_into_free_list(list); 6078 } 6079 } 6080 6081 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) { 6082 assert(_summary_bytes_used >= bytes, 6083 err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" should be >= bytes: "SIZE_FORMAT, 6084 _summary_bytes_used, bytes)); 6085 _summary_bytes_used -= bytes; 6086 } 6087 6088 class G1ParCleanupCTTask : public AbstractGangTask { 6089 G1SATBCardTableModRefBS* _ct_bs; 6090 G1CollectedHeap* _g1h; 6091 HeapRegion* volatile _su_head; 6092 public: 6093 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs, 6094 G1CollectedHeap* g1h) : 6095 AbstractGangTask("G1 Par Cleanup CT Task"), 6096 _ct_bs(ct_bs), _g1h(g1h) { } 6097 6098 void work(uint worker_id) { 6099 HeapRegion* r; 6100 while (r = _g1h->pop_dirty_cards_region()) { 6101 clear_cards(r); 6102 } 6103 } 6104 6105 void clear_cards(HeapRegion* r) { 6106 // Cards of the survivors should have already been dirtied. 6107 if (!r->is_survivor()) { 6108 _ct_bs->clear(MemRegion(r->bottom(), r->end())); 6109 } 6110 } 6111 }; 6112 6113 #ifndef PRODUCT 6114 class G1VerifyCardTableCleanup: public HeapRegionClosure { 6115 G1CollectedHeap* _g1h; 6116 G1SATBCardTableModRefBS* _ct_bs; 6117 public: 6118 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs) 6119 : _g1h(g1h), _ct_bs(ct_bs) { } 6120 virtual bool doHeapRegion(HeapRegion* r) { 6121 if (r->is_survivor()) { 6122 _g1h->verify_dirty_region(r); 6123 } else { 6124 _g1h->verify_not_dirty_region(r); 6125 } 6126 return false; 6127 } 6128 }; 6129 6130 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) { 6131 // All of the region should be clean. 6132 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 6133 MemRegion mr(hr->bottom(), hr->end()); 6134 ct_bs->verify_not_dirty_region(mr); 6135 } 6136 6137 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) { 6138 // We cannot guarantee that [bottom(),end()] is dirty. Threads 6139 // dirty allocated blocks as they allocate them. The thread that 6140 // retires each region and replaces it with a new one will do a 6141 // maximal allocation to fill in [pre_dummy_top(),end()] but will 6142 // not dirty that area (one less thing to have to do while holding 6143 // a lock). So we can only verify that [bottom(),pre_dummy_top()] 6144 // is dirty. 6145 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 6146 MemRegion mr(hr->bottom(), hr->pre_dummy_top()); 6147 if (hr->is_young()) { 6148 ct_bs->verify_g1_young_region(mr); 6149 } else { 6150 ct_bs->verify_dirty_region(mr); 6151 } 6152 } 6153 6154 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) { 6155 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 6156 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) { 6157 verify_dirty_region(hr); 6158 } 6159 } 6160 6161 void G1CollectedHeap::verify_dirty_young_regions() { 6162 verify_dirty_young_list(_young_list->first_region()); 6163 } 6164 6165 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap, 6166 HeapWord* tams, HeapWord* end) { 6167 guarantee(tams <= end, 6168 err_msg("tams: "PTR_FORMAT" end: "PTR_FORMAT, tams, end)); 6169 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end); 6170 if (result < end) { 6171 gclog_or_tty->cr(); 6172 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: "PTR_FORMAT, 6173 bitmap_name, result); 6174 gclog_or_tty->print_cr("## %s tams: "PTR_FORMAT" end: "PTR_FORMAT, 6175 bitmap_name, tams, end); 6176 return false; 6177 } 6178 return true; 6179 } 6180 6181 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) { 6182 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap(); 6183 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap(); 6184 6185 HeapWord* bottom = hr->bottom(); 6186 HeapWord* ptams = hr->prev_top_at_mark_start(); 6187 HeapWord* ntams = hr->next_top_at_mark_start(); 6188 HeapWord* end = hr->end(); 6189 6190 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end); 6191 6192 bool res_n = true; 6193 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window 6194 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap 6195 // if we happen to be in that state. 6196 if (mark_in_progress() || !_cmThread->in_progress()) { 6197 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end); 6198 } 6199 if (!res_p || !res_n) { 6200 gclog_or_tty->print_cr("#### Bitmap verification failed for "HR_FORMAT, 6201 HR_FORMAT_PARAMS(hr)); 6202 gclog_or_tty->print_cr("#### Caller: %s", caller); 6203 return false; 6204 } 6205 return true; 6206 } 6207 6208 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) { 6209 if (!G1VerifyBitmaps) return; 6210 6211 guarantee(verify_bitmaps(caller, hr), "bitmap verification"); 6212 } 6213 6214 class G1VerifyBitmapClosure : public HeapRegionClosure { 6215 private: 6216 const char* _caller; 6217 G1CollectedHeap* _g1h; 6218 bool _failures; 6219 6220 public: 6221 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) : 6222 _caller(caller), _g1h(g1h), _failures(false) { } 6223 6224 bool failures() { return _failures; } 6225 6226 virtual bool doHeapRegion(HeapRegion* hr) { 6227 if (hr->continuesHumongous()) return false; 6228 6229 bool result = _g1h->verify_bitmaps(_caller, hr); 6230 if (!result) { 6231 _failures = true; 6232 } 6233 return false; 6234 } 6235 }; 6236 6237 void G1CollectedHeap::check_bitmaps(const char* caller) { 6238 if (!G1VerifyBitmaps) return; 6239 6240 G1VerifyBitmapClosure cl(caller, this); 6241 heap_region_iterate(&cl); 6242 guarantee(!cl.failures(), "bitmap verification"); 6243 } 6244 #endif // PRODUCT 6245 6246 void G1CollectedHeap::cleanUpCardTable() { 6247 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 6248 double start = os::elapsedTime(); 6249 6250 { 6251 // Iterate over the dirty cards region list. 6252 G1ParCleanupCTTask cleanup_task(ct_bs, this); 6253 6254 if (G1CollectedHeap::use_parallel_gc_threads()) { 6255 set_par_threads(); 6256 workers()->run_task(&cleanup_task); 6257 set_par_threads(0); 6258 } else { 6259 while (_dirty_cards_region_list) { 6260 HeapRegion* r = _dirty_cards_region_list; 6261 cleanup_task.clear_cards(r); 6262 _dirty_cards_region_list = r->get_next_dirty_cards_region(); 6263 if (_dirty_cards_region_list == r) { 6264 // The last region. 6265 _dirty_cards_region_list = NULL; 6266 } 6267 r->set_next_dirty_cards_region(NULL); 6268 } 6269 } 6270 #ifndef PRODUCT 6271 if (G1VerifyCTCleanup || VerifyAfterGC) { 6272 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs); 6273 heap_region_iterate(&cleanup_verifier); 6274 } 6275 #endif 6276 } 6277 6278 double elapsed = os::elapsedTime() - start; 6279 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0); 6280 } 6281 6282 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) { 6283 size_t pre_used = 0; 6284 FreeRegionList local_free_list("Local List for CSet Freeing"); 6285 6286 double young_time_ms = 0.0; 6287 double non_young_time_ms = 0.0; 6288 6289 // Since the collection set is a superset of the the young list, 6290 // all we need to do to clear the young list is clear its 6291 // head and length, and unlink any young regions in the code below 6292 _young_list->clear(); 6293 6294 G1CollectorPolicy* policy = g1_policy(); 6295 6296 double start_sec = os::elapsedTime(); 6297 bool non_young = true; 6298 6299 HeapRegion* cur = cs_head; 6300 int age_bound = -1; 6301 size_t rs_lengths = 0; 6302 6303 while (cur != NULL) { 6304 assert(!is_on_master_free_list(cur), "sanity"); 6305 if (non_young) { 6306 if (cur->is_young()) { 6307 double end_sec = os::elapsedTime(); 6308 double elapsed_ms = (end_sec - start_sec) * 1000.0; 6309 non_young_time_ms += elapsed_ms; 6310 6311 start_sec = os::elapsedTime(); 6312 non_young = false; 6313 } 6314 } else { 6315 if (!cur->is_young()) { 6316 double end_sec = os::elapsedTime(); 6317 double elapsed_ms = (end_sec - start_sec) * 1000.0; 6318 young_time_ms += elapsed_ms; 6319 6320 start_sec = os::elapsedTime(); 6321 non_young = true; 6322 } 6323 } 6324 6325 rs_lengths += cur->rem_set()->occupied_locked(); 6326 6327 HeapRegion* next = cur->next_in_collection_set(); 6328 assert(cur->in_collection_set(), "bad CS"); 6329 cur->set_next_in_collection_set(NULL); 6330 cur->set_in_collection_set(false); 6331 6332 if (cur->is_young()) { 6333 int index = cur->young_index_in_cset(); 6334 assert(index != -1, "invariant"); 6335 assert((uint) index < policy->young_cset_region_length(), "invariant"); 6336 size_t words_survived = _surviving_young_words[index]; 6337 cur->record_surv_words_in_group(words_survived); 6338 6339 // At this point the we have 'popped' cur from the collection set 6340 // (linked via next_in_collection_set()) but it is still in the 6341 // young list (linked via next_young_region()). Clear the 6342 // _next_young_region field. 6343 cur->set_next_young_region(NULL); 6344 } else { 6345 int index = cur->young_index_in_cset(); 6346 assert(index == -1, "invariant"); 6347 } 6348 6349 assert( (cur->is_young() && cur->young_index_in_cset() > -1) || 6350 (!cur->is_young() && cur->young_index_in_cset() == -1), 6351 "invariant" ); 6352 6353 if (!cur->evacuation_failed()) { 6354 MemRegion used_mr = cur->used_region(); 6355 6356 // And the region is empty. 6357 assert(!used_mr.is_empty(), "Should not have empty regions in a CS."); 6358 pre_used += cur->used(); 6359 free_region(cur, &local_free_list, false /* par */, true /* locked */); 6360 } else { 6361 cur->uninstall_surv_rate_group(); 6362 if (cur->is_young()) { 6363 cur->set_young_index_in_cset(-1); 6364 } 6365 cur->set_not_young(); 6366 cur->set_evacuation_failed(false); 6367 // The region is now considered to be old. 6368 _old_set.add(cur); 6369 evacuation_info.increment_collectionset_used_after(cur->used()); 6370 } 6371 cur = next; 6372 } 6373 6374 evacuation_info.set_regions_freed(local_free_list.length()); 6375 policy->record_max_rs_lengths(rs_lengths); 6376 policy->cset_regions_freed(); 6377 6378 double end_sec = os::elapsedTime(); 6379 double elapsed_ms = (end_sec - start_sec) * 1000.0; 6380 6381 if (non_young) { 6382 non_young_time_ms += elapsed_ms; 6383 } else { 6384 young_time_ms += elapsed_ms; 6385 } 6386 6387 prepend_to_freelist(&local_free_list); 6388 decrement_summary_bytes(pre_used); 6389 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms); 6390 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms); 6391 } 6392 6393 class G1FreeHumongousRegionClosure : public HeapRegionClosure { 6394 private: 6395 FreeRegionList* _free_region_list; 6396 HeapRegionSet* _proxy_set; 6397 HeapRegionSetCount _humongous_regions_removed; 6398 size_t _freed_bytes; 6399 public: 6400 6401 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) : 6402 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) { 6403 } 6404 6405 virtual bool doHeapRegion(HeapRegion* r) { 6406 if (!r->startsHumongous()) { 6407 return false; 6408 } 6409 6410 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 6411 6412 oop obj = (oop)r->bottom(); 6413 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap(); 6414 6415 // The following checks whether the humongous object is live are sufficient. 6416 // The main additional check (in addition to having a reference from the roots 6417 // or the young gen) is whether the humongous object has a remembered set entry. 6418 // 6419 // A humongous object cannot be live if there is no remembered set for it 6420 // because: 6421 // - there can be no references from within humongous starts regions referencing 6422 // the object because we never allocate other objects into them. 6423 // (I.e. there are no intra-region references that may be missed by the 6424 // remembered set) 6425 // - as soon there is a remembered set entry to the humongous starts region 6426 // (i.e. it has "escaped" to an old object) this remembered set entry will stay 6427 // until the end of a concurrent mark. 6428 // 6429 // It is not required to check whether the object has been found dead by marking 6430 // or not, in fact it would prevent reclamation within a concurrent cycle, as 6431 // all objects allocated during that time are considered live. 6432 // SATB marking is even more conservative than the remembered set. 6433 // So if at this point in the collection there is no remembered set entry, 6434 // nobody has a reference to it. 6435 // At the start of collection we flush all refinement logs, and remembered sets 6436 // are completely up-to-date wrt to references to the humongous object. 6437 // 6438 // Other implementation considerations: 6439 // - never consider object arrays: while they are a valid target, they have not 6440 // been observed to be used as temporary objects. 6441 // - they would also pose considerable effort for cleaning up the the remembered 6442 // sets. 6443 // While this cleanup is not strictly necessary to be done (or done instantly), 6444 // given that their occurrence is very low, this saves us this additional 6445 // complexity. 6446 uint region_idx = r->hrs_index(); 6447 if (g1h->humongous_is_live(region_idx) || 6448 g1h->humongous_region_is_always_live(region_idx)) { 6449 6450 if (G1TraceReclaimDeadHumongousObjectsAtYoungGC) { 6451 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", 6452 r->isHumongous(), 6453 region_idx, 6454 r->rem_set()->occupied(), 6455 r->rem_set()->strong_code_roots_list_length(), 6456 next_bitmap->isMarked(r->bottom()), 6457 g1h->humongous_is_live(region_idx), 6458 obj->is_objArray() 6459 ); 6460 } 6461 6462 return false; 6463 } 6464 6465 guarantee(!obj->is_objArray(), 6466 err_msg("Eagerly reclaiming object arrays is not supported, but the object "PTR_FORMAT" is.", 6467 r->bottom())); 6468 6469 if (G1TraceReclaimDeadHumongousObjectsAtYoungGC) { 6470 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", 6471 r->isHumongous(), 6472 r->bottom(), 6473 region_idx, 6474 r->region_num(), 6475 r->rem_set()->occupied(), 6476 r->rem_set()->strong_code_roots_list_length(), 6477 next_bitmap->isMarked(r->bottom()), 6478 g1h->humongous_is_live(region_idx), 6479 obj->is_objArray() 6480 ); 6481 } 6482 // Need to clear mark bit of the humongous object if already set. 6483 if (next_bitmap->isMarked(r->bottom())) { 6484 next_bitmap->clear(r->bottom()); 6485 } 6486 _freed_bytes += r->used(); 6487 r->set_containing_set(NULL); 6488 _humongous_regions_removed.increment(1u, r->capacity()); 6489 g1h->free_humongous_region(r, _free_region_list, false); 6490 6491 return false; 6492 } 6493 6494 HeapRegionSetCount& humongous_free_count() { 6495 return _humongous_regions_removed; 6496 } 6497 6498 size_t bytes_freed() const { 6499 return _freed_bytes; 6500 } 6501 6502 size_t humongous_reclaimed() const { 6503 return _humongous_regions_removed.length(); 6504 } 6505 }; 6506 6507 void G1CollectedHeap::eagerly_reclaim_humongous_regions() { 6508 assert_at_safepoint(true); 6509 6510 if (!G1ReclaimDeadHumongousObjectsAtYoungGC || !_has_humongous_reclaim_candidates) { 6511 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0); 6512 return; 6513 } 6514 6515 double start_time = os::elapsedTime(); 6516 6517 FreeRegionList local_cleanup_list("Local Humongous Cleanup List"); 6518 6519 G1FreeHumongousRegionClosure cl(&local_cleanup_list); 6520 heap_region_iterate(&cl); 6521 6522 HeapRegionSetCount empty_set; 6523 remove_from_old_sets(empty_set, cl.humongous_free_count()); 6524 6525 G1HRPrinter* hr_printer = _g1h->hr_printer(); 6526 if (hr_printer->is_active()) { 6527 FreeRegionListIterator iter(&local_cleanup_list); 6528 while (iter.more_available()) { 6529 HeapRegion* hr = iter.get_next(); 6530 hr_printer->cleanup(hr); 6531 } 6532 } 6533 6534 prepend_to_freelist(&local_cleanup_list); 6535 decrement_summary_bytes(cl.bytes_freed()); 6536 6537 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0, 6538 cl.humongous_reclaimed()); 6539 } 6540 6541 // This routine is similar to the above but does not record 6542 // any policy statistics or update free lists; we are abandoning 6543 // the current incremental collection set in preparation of a 6544 // full collection. After the full GC we will start to build up 6545 // the incremental collection set again. 6546 // This is only called when we're doing a full collection 6547 // and is immediately followed by the tearing down of the young list. 6548 6549 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) { 6550 HeapRegion* cur = cs_head; 6551 6552 while (cur != NULL) { 6553 HeapRegion* next = cur->next_in_collection_set(); 6554 assert(cur->in_collection_set(), "bad CS"); 6555 cur->set_next_in_collection_set(NULL); 6556 cur->set_in_collection_set(false); 6557 cur->set_young_index_in_cset(-1); 6558 cur = next; 6559 } 6560 } 6561 6562 void G1CollectedHeap::set_free_regions_coming() { 6563 if (G1ConcRegionFreeingVerbose) { 6564 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " 6565 "setting free regions coming"); 6566 } 6567 6568 assert(!free_regions_coming(), "pre-condition"); 6569 _free_regions_coming = true; 6570 } 6571 6572 void G1CollectedHeap::reset_free_regions_coming() { 6573 assert(free_regions_coming(), "pre-condition"); 6574 6575 { 6576 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6577 _free_regions_coming = false; 6578 SecondaryFreeList_lock->notify_all(); 6579 } 6580 6581 if (G1ConcRegionFreeingVerbose) { 6582 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " 6583 "reset free regions coming"); 6584 } 6585 } 6586 6587 void G1CollectedHeap::wait_while_free_regions_coming() { 6588 // Most of the time we won't have to wait, so let's do a quick test 6589 // first before we take the lock. 6590 if (!free_regions_coming()) { 6591 return; 6592 } 6593 6594 if (G1ConcRegionFreeingVerbose) { 6595 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " 6596 "waiting for free regions"); 6597 } 6598 6599 { 6600 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6601 while (free_regions_coming()) { 6602 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 6603 } 6604 } 6605 6606 if (G1ConcRegionFreeingVerbose) { 6607 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " 6608 "done waiting for free regions"); 6609 } 6610 } 6611 6612 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 6613 assert(heap_lock_held_for_gc(), 6614 "the heap lock should already be held by or for this thread"); 6615 _young_list->push_region(hr); 6616 } 6617 6618 class NoYoungRegionsClosure: public HeapRegionClosure { 6619 private: 6620 bool _success; 6621 public: 6622 NoYoungRegionsClosure() : _success(true) { } 6623 bool doHeapRegion(HeapRegion* r) { 6624 if (r->is_young()) { 6625 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young", 6626 r->bottom(), r->end()); 6627 _success = false; 6628 } 6629 return false; 6630 } 6631 bool success() { return _success; } 6632 }; 6633 6634 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) { 6635 bool ret = _young_list->check_list_empty(check_sample); 6636 6637 if (check_heap) { 6638 NoYoungRegionsClosure closure; 6639 heap_region_iterate(&closure); 6640 ret = ret && closure.success(); 6641 } 6642 6643 return ret; 6644 } 6645 6646 class TearDownRegionSetsClosure : public HeapRegionClosure { 6647 private: 6648 HeapRegionSet *_old_set; 6649 6650 public: 6651 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { } 6652 6653 bool doHeapRegion(HeapRegion* r) { 6654 if (r->is_empty()) { 6655 // We ignore empty regions, we'll empty the free list afterwards 6656 } else if (r->is_young()) { 6657 // We ignore young regions, we'll empty the young list afterwards 6658 } else if (r->isHumongous()) { 6659 // We ignore humongous regions, we're not tearing down the 6660 // humongous region set 6661 } else { 6662 // The rest should be old 6663 _old_set->remove(r); 6664 } 6665 return false; 6666 } 6667 6668 ~TearDownRegionSetsClosure() { 6669 assert(_old_set->is_empty(), "post-condition"); 6670 } 6671 }; 6672 6673 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) { 6674 assert_at_safepoint(true /* should_be_vm_thread */); 6675 6676 if (!free_list_only) { 6677 TearDownRegionSetsClosure cl(&_old_set); 6678 heap_region_iterate(&cl); 6679 6680 // Note that emptying the _young_list is postponed and instead done as 6681 // the first step when rebuilding the regions sets again. The reason for 6682 // this is that during a full GC string deduplication needs to know if 6683 // a collected region was young or old when the full GC was initiated. 6684 } 6685 _hrs.remove_all_free_regions(); 6686 } 6687 6688 class RebuildRegionSetsClosure : public HeapRegionClosure { 6689 private: 6690 bool _free_list_only; 6691 HeapRegionSet* _old_set; 6692 HeapRegionSeq* _hrs; 6693 size_t _total_used; 6694 6695 public: 6696 RebuildRegionSetsClosure(bool free_list_only, 6697 HeapRegionSet* old_set, HeapRegionSeq* hrs) : 6698 _free_list_only(free_list_only), 6699 _old_set(old_set), _hrs(hrs), _total_used(0) { 6700 assert(_hrs->num_free_regions() == 0, "pre-condition"); 6701 if (!free_list_only) { 6702 assert(_old_set->is_empty(), "pre-condition"); 6703 } 6704 } 6705 6706 bool doHeapRegion(HeapRegion* r) { 6707 if (r->continuesHumongous()) { 6708 return false; 6709 } 6710 6711 if (r->is_empty()) { 6712 // Add free regions to the free list 6713 _hrs->insert_into_free_list(r); 6714 } else if (!_free_list_only) { 6715 assert(!r->is_young(), "we should not come across young regions"); 6716 6717 if (r->isHumongous()) { 6718 // We ignore humongous regions, we left the humongous set unchanged 6719 } else { 6720 // The rest should be old, add them to the old set 6721 _old_set->add(r); 6722 } 6723 _total_used += r->used(); 6724 } 6725 6726 return false; 6727 } 6728 6729 size_t total_used() { 6730 return _total_used; 6731 } 6732 }; 6733 6734 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { 6735 assert_at_safepoint(true /* should_be_vm_thread */); 6736 6737 if (!free_list_only) { 6738 _young_list->empty_list(); 6739 } 6740 6741 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrs); 6742 heap_region_iterate(&cl); 6743 6744 if (!free_list_only) { 6745 _summary_bytes_used = cl.total_used(); 6746 } 6747 assert(_summary_bytes_used == recalculate_used(), 6748 err_msg("inconsistent _summary_bytes_used, " 6749 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT, 6750 _summary_bytes_used, recalculate_used())); 6751 } 6752 6753 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) { 6754 _refine_cte_cl->set_concurrent(concurrent); 6755 } 6756 6757 bool G1CollectedHeap::is_in_closed_subset(const void* p) const { 6758 HeapRegion* hr = heap_region_containing(p); 6759 return hr->is_in(p); 6760 } 6761 6762 // Methods for the mutator alloc region 6763 6764 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 6765 bool force) { 6766 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6767 assert(!force || g1_policy()->can_expand_young_list(), 6768 "if force is true we should be able to expand the young list"); 6769 bool young_list_full = g1_policy()->is_young_list_full(); 6770 if (force || !young_list_full) { 6771 HeapRegion* new_alloc_region = new_region(word_size, 6772 false /* is_old */, 6773 false /* do_expand */); 6774 if (new_alloc_region != NULL) { 6775 set_region_short_lived_locked(new_alloc_region); 6776 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full); 6777 check_bitmaps("Mutator Region Allocation", new_alloc_region); 6778 return new_alloc_region; 6779 } 6780 } 6781 return NULL; 6782 } 6783 6784 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 6785 size_t allocated_bytes) { 6786 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6787 assert(alloc_region->is_young(), "all mutator alloc regions should be young"); 6788 6789 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region); 6790 _summary_bytes_used += allocated_bytes; 6791 _hr_printer.retire(alloc_region); 6792 // We update the eden sizes here, when the region is retired, 6793 // instead of when it's allocated, since this is the point that its 6794 // used space has been recored in _summary_bytes_used. 6795 g1mm()->update_eden_size(); 6796 } 6797 6798 HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size, 6799 bool force) { 6800 return _g1h->new_mutator_alloc_region(word_size, force); 6801 } 6802 6803 void G1CollectedHeap::set_par_threads() { 6804 // Don't change the number of workers. Use the value previously set 6805 // in the workgroup. 6806 assert(G1CollectedHeap::use_parallel_gc_threads(), "shouldn't be here otherwise"); 6807 uint n_workers = workers()->active_workers(); 6808 assert(UseDynamicNumberOfGCThreads || 6809 n_workers == workers()->total_workers(), 6810 "Otherwise should be using the total number of workers"); 6811 if (n_workers == 0) { 6812 assert(false, "Should have been set in prior evacuation pause."); 6813 n_workers = ParallelGCThreads; 6814 workers()->set_active_workers(n_workers); 6815 } 6816 set_par_threads(n_workers); 6817 } 6818 6819 void MutatorAllocRegion::retire_region(HeapRegion* alloc_region, 6820 size_t allocated_bytes) { 6821 _g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes); 6822 } 6823 6824 // Methods for the GC alloc regions 6825 6826 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, 6827 uint count, 6828 GCAllocPurpose ap) { 6829 assert(FreeList_lock->owned_by_self(), "pre-condition"); 6830 6831 if (count < g1_policy()->max_regions(ap)) { 6832 bool survivor = (ap == GCAllocForSurvived); 6833 HeapRegion* new_alloc_region = new_region(word_size, 6834 !survivor, 6835 true /* do_expand */); 6836 if (new_alloc_region != NULL) { 6837 // We really only need to do this for old regions given that we 6838 // should never scan survivors. But it doesn't hurt to do it 6839 // for survivors too. 6840 new_alloc_region->record_top_and_timestamp(); 6841 if (survivor) { 6842 new_alloc_region->set_survivor(); 6843 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor); 6844 check_bitmaps("Survivor Region Allocation", new_alloc_region); 6845 } else { 6846 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old); 6847 check_bitmaps("Old Region Allocation", new_alloc_region); 6848 } 6849 bool during_im = g1_policy()->during_initial_mark_pause(); 6850 new_alloc_region->note_start_of_copying(during_im); 6851 return new_alloc_region; 6852 } else { 6853 g1_policy()->note_alloc_region_limit_reached(ap); 6854 } 6855 } 6856 return NULL; 6857 } 6858 6859 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 6860 size_t allocated_bytes, 6861 GCAllocPurpose ap) { 6862 bool during_im = g1_policy()->during_initial_mark_pause(); 6863 alloc_region->note_end_of_copying(during_im); 6864 g1_policy()->record_bytes_copied_during_gc(allocated_bytes); 6865 if (ap == GCAllocForSurvived) { 6866 young_list()->add_survivor_region(alloc_region); 6867 } else { 6868 _old_set.add(alloc_region); 6869 } 6870 _hr_printer.retire(alloc_region); 6871 } 6872 6873 HeapRegion* SurvivorGCAllocRegion::allocate_new_region(size_t word_size, 6874 bool force) { 6875 assert(!force, "not supported for GC alloc regions"); 6876 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForSurvived); 6877 } 6878 6879 void SurvivorGCAllocRegion::retire_region(HeapRegion* alloc_region, 6880 size_t allocated_bytes) { 6881 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes, 6882 GCAllocForSurvived); 6883 } 6884 6885 HeapRegion* OldGCAllocRegion::allocate_new_region(size_t word_size, 6886 bool force) { 6887 assert(!force, "not supported for GC alloc regions"); 6888 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForTenured); 6889 } 6890 6891 void OldGCAllocRegion::retire_region(HeapRegion* alloc_region, 6892 size_t allocated_bytes) { 6893 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes, 6894 GCAllocForTenured); 6895 } 6896 6897 HeapRegion* OldGCAllocRegion::release() { 6898 HeapRegion* cur = get(); 6899 if (cur != NULL) { 6900 // Determine how far we are from the next card boundary. If it is smaller than 6901 // the minimum object size we can allocate into, expand into the next card. 6902 HeapWord* top = cur->top(); 6903 HeapWord* aligned_top = (HeapWord*)align_ptr_up(top, G1BlockOffsetSharedArray::N_bytes); 6904 6905 size_t to_allocate_words = pointer_delta(aligned_top, top, HeapWordSize); 6906 6907 if (to_allocate_words != 0) { 6908 // We are not at a card boundary. Fill up, possibly into the next, taking the 6909 // end of the region and the minimum object size into account. 6910 to_allocate_words = MIN2(pointer_delta(cur->end(), cur->top(), HeapWordSize), 6911 MAX2(to_allocate_words, G1CollectedHeap::min_fill_size())); 6912 6913 // Skip allocation if there is not enough space to allocate even the smallest 6914 // possible object. In this case this region will not be retained, so the 6915 // original problem cannot occur. 6916 if (to_allocate_words >= G1CollectedHeap::min_fill_size()) { 6917 HeapWord* dummy = attempt_allocation(to_allocate_words, true /* bot_updates */); 6918 CollectedHeap::fill_with_object(dummy, to_allocate_words); 6919 } 6920 } 6921 } 6922 return G1AllocRegion::release(); 6923 } 6924 6925 // Heap region set verification 6926 6927 class VerifyRegionListsClosure : public HeapRegionClosure { 6928 private: 6929 HeapRegionSet* _old_set; 6930 HeapRegionSet* _humongous_set; 6931 HeapRegionSeq* _hrs; 6932 6933 public: 6934 HeapRegionSetCount _old_count; 6935 HeapRegionSetCount _humongous_count; 6936 HeapRegionSetCount _free_count; 6937 6938 VerifyRegionListsClosure(HeapRegionSet* old_set, 6939 HeapRegionSet* humongous_set, 6940 HeapRegionSeq* hrs) : 6941 _old_set(old_set), _humongous_set(humongous_set), _hrs(hrs), 6942 _old_count(), _humongous_count(), _free_count(){ } 6943 6944 bool doHeapRegion(HeapRegion* hr) { 6945 if (hr->continuesHumongous()) { 6946 return false; 6947 } 6948 6949 if (hr->is_young()) { 6950 // TODO 6951 } else if (hr->startsHumongous()) { 6952 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrs_index())); 6953 _humongous_count.increment(1u, hr->capacity()); 6954 } else if (hr->is_empty()) { 6955 assert(_hrs->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrs_index())); 6956 _free_count.increment(1u, hr->capacity()); 6957 } else { 6958 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrs_index())); 6959 _old_count.increment(1u, hr->capacity()); 6960 } 6961 return false; 6962 } 6963 6964 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionSeq* free_list) { 6965 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length())); 6966 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6967 old_set->total_capacity_bytes(), _old_count.capacity())); 6968 6969 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length())); 6970 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6971 humongous_set->total_capacity_bytes(), _humongous_count.capacity())); 6972 6973 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())); 6974 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6975 free_list->total_capacity_bytes(), _free_count.capacity())); 6976 } 6977 }; 6978 6979 void G1CollectedHeap::verify_region_sets() { 6980 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6981 6982 // First, check the explicit lists. 6983 _hrs.verify(); 6984 { 6985 // Given that a concurrent operation might be adding regions to 6986 // the secondary free list we have to take the lock before 6987 // verifying it. 6988 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6989 _secondary_free_list.verify_list(); 6990 } 6991 6992 // If a concurrent region freeing operation is in progress it will 6993 // be difficult to correctly attributed any free regions we come 6994 // across to the correct free list given that they might belong to 6995 // one of several (free_list, secondary_free_list, any local lists, 6996 // etc.). So, if that's the case we will skip the rest of the 6997 // verification operation. Alternatively, waiting for the concurrent 6998 // operation to complete will have a non-trivial effect on the GC's 6999 // operation (no concurrent operation will last longer than the 7000 // interval between two calls to verification) and it might hide 7001 // any issues that we would like to catch during testing. 7002 if (free_regions_coming()) { 7003 return; 7004 } 7005 7006 // Make sure we append the secondary_free_list on the free_list so 7007 // that all free regions we will come across can be safely 7008 // attributed to the free_list. 7009 append_secondary_free_list_if_not_empty_with_lock(); 7010 7011 // Finally, make sure that the region accounting in the lists is 7012 // consistent with what we see in the heap. 7013 7014 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrs); 7015 heap_region_iterate(&cl); 7016 cl.verify_counts(&_old_set, &_humongous_set, &_hrs); 7017 } 7018 7019 // Optimized nmethod scanning 7020 7021 class RegisterNMethodOopClosure: public OopClosure { 7022 G1CollectedHeap* _g1h; 7023 nmethod* _nm; 7024 7025 template <class T> void do_oop_work(T* p) { 7026 T heap_oop = oopDesc::load_heap_oop(p); 7027 if (!oopDesc::is_null(heap_oop)) { 7028 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 7029 HeapRegion* hr = _g1h->heap_region_containing(obj); 7030 assert(!hr->continuesHumongous(), 7031 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT 7032 " starting at "HR_FORMAT, 7033 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()))); 7034 7035 // HeapRegion::add_strong_code_root() avoids adding duplicate 7036 // entries but having duplicates is OK since we "mark" nmethods 7037 // as visited when we scan the strong code root lists during the GC. 7038 hr->add_strong_code_root(_nm); 7039 assert(hr->rem_set()->strong_code_roots_list_contains(_nm), 7040 err_msg("failed to add code root "PTR_FORMAT" to remembered set of region "HR_FORMAT, 7041 _nm, HR_FORMAT_PARAMS(hr))); 7042 } 7043 } 7044 7045 public: 7046 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 7047 _g1h(g1h), _nm(nm) {} 7048 7049 void do_oop(oop* p) { do_oop_work(p); } 7050 void do_oop(narrowOop* p) { do_oop_work(p); } 7051 }; 7052 7053 class UnregisterNMethodOopClosure: public OopClosure { 7054 G1CollectedHeap* _g1h; 7055 nmethod* _nm; 7056 7057 template <class T> void do_oop_work(T* p) { 7058 T heap_oop = oopDesc::load_heap_oop(p); 7059 if (!oopDesc::is_null(heap_oop)) { 7060 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 7061 HeapRegion* hr = _g1h->heap_region_containing(obj); 7062 assert(!hr->continuesHumongous(), 7063 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT 7064 " starting at "HR_FORMAT, 7065 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()))); 7066 7067 hr->remove_strong_code_root(_nm); 7068 assert(!hr->rem_set()->strong_code_roots_list_contains(_nm), 7069 err_msg("failed to remove code root "PTR_FORMAT" of region "HR_FORMAT, 7070 _nm, HR_FORMAT_PARAMS(hr))); 7071 } 7072 } 7073 7074 public: 7075 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 7076 _g1h(g1h), _nm(nm) {} 7077 7078 void do_oop(oop* p) { do_oop_work(p); } 7079 void do_oop(narrowOop* p) { do_oop_work(p); } 7080 }; 7081 7082 void G1CollectedHeap::register_nmethod(nmethod* nm) { 7083 CollectedHeap::register_nmethod(nm); 7084 7085 guarantee(nm != NULL, "sanity"); 7086 RegisterNMethodOopClosure reg_cl(this, nm); 7087 nm->oops_do(®_cl); 7088 } 7089 7090 void G1CollectedHeap::unregister_nmethod(nmethod* nm) { 7091 CollectedHeap::unregister_nmethod(nm); 7092 7093 guarantee(nm != NULL, "sanity"); 7094 UnregisterNMethodOopClosure reg_cl(this, nm); 7095 nm->oops_do(®_cl, true); 7096 } 7097 7098 class MigrateCodeRootsHeapRegionClosure: public HeapRegionClosure { 7099 public: 7100 bool doHeapRegion(HeapRegion *hr) { 7101 assert(!hr->isHumongous(), 7102 err_msg("humongous region "HR_FORMAT" should not have been added to collection set", 7103 HR_FORMAT_PARAMS(hr))); 7104 hr->migrate_strong_code_roots(); 7105 return false; 7106 } 7107 }; 7108 7109 void G1CollectedHeap::migrate_strong_code_roots() { 7110 MigrateCodeRootsHeapRegionClosure cl; 7111 double migrate_start = os::elapsedTime(); 7112 collection_set_iterate(&cl); 7113 double migration_time_ms = (os::elapsedTime() - migrate_start) * 1000.0; 7114 g1_policy()->phase_times()->record_strong_code_root_migration_time(migration_time_ms); 7115 } 7116 7117 void G1CollectedHeap::purge_code_root_memory() { 7118 double purge_start = os::elapsedTime(); 7119 G1CodeRootSet::purge_chunks(G1CodeRootsChunkCacheKeepPercent); 7120 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0; 7121 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms); 7122 } 7123 7124 class RebuildStrongCodeRootClosure: public CodeBlobClosure { 7125 G1CollectedHeap* _g1h; 7126 7127 public: 7128 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) : 7129 _g1h(g1h) {} 7130 7131 void do_code_blob(CodeBlob* cb) { 7132 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL; 7133 if (nm == NULL) { 7134 return; 7135 } 7136 7137 if (ScavengeRootsInCode) { 7138 _g1h->register_nmethod(nm); 7139 } 7140 } 7141 }; 7142 7143 void G1CollectedHeap::rebuild_strong_code_roots() { 7144 RebuildStrongCodeRootClosure blob_cl(this); 7145 CodeCache::blobs_do(&blob_cl); 7146 }