1 /* 2 * Copyright (c) 2001, 2014, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #if !defined(__clang_major__) && defined(__GNUC__) 26 // FIXME, formats have issues. Disable this macro definition, compile, and study warnings for more information. 27 #define ATTRIBUTE_PRINTF(x,y) 28 #endif 29 30 #include "precompiled.hpp" 31 #include "classfile/stringTable.hpp" 32 #include "code/codeCache.hpp" 33 #include "code/icBuffer.hpp" 34 #include "gc_implementation/g1/bufferingOopClosure.hpp" 35 #include "gc_implementation/g1/concurrentG1Refine.hpp" 36 #include "gc_implementation/g1/concurrentG1RefineThread.hpp" 37 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp" 38 #include "gc_implementation/g1/g1AllocRegion.inline.hpp" 39 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp" 40 #include "gc_implementation/g1/g1CollectorPolicy.hpp" 41 #include "gc_implementation/g1/g1ErgoVerbose.hpp" 42 #include "gc_implementation/g1/g1EvacFailure.hpp" 43 #include "gc_implementation/g1/g1GCPhaseTimes.hpp" 44 #include "gc_implementation/g1/g1Log.hpp" 45 #include "gc_implementation/g1/g1MarkSweep.hpp" 46 #include "gc_implementation/g1/g1OopClosures.inline.hpp" 47 #include "gc_implementation/g1/g1ParScanThreadState.inline.hpp" 48 #include "gc_implementation/g1/g1RegionToSpaceMapper.hpp" 49 #include "gc_implementation/g1/g1RemSet.inline.hpp" 50 #include "gc_implementation/g1/g1StringDedup.hpp" 51 #include "gc_implementation/g1/g1YCTypes.hpp" 52 #include "gc_implementation/g1/heapRegion.inline.hpp" 53 #include "gc_implementation/g1/heapRegionRemSet.hpp" 54 #include "gc_implementation/g1/heapRegionSet.inline.hpp" 55 #include "gc_implementation/g1/vm_operations_g1.hpp" 56 #include "gc_implementation/shared/gcHeapSummary.hpp" 57 #include "gc_implementation/shared/gcTimer.hpp" 58 #include "gc_implementation/shared/gcTrace.hpp" 59 #include "gc_implementation/shared/gcTraceTime.hpp" 60 #include "gc_implementation/shared/isGCActiveMark.hpp" 61 #include "memory/allocation.hpp" 62 #include "memory/gcLocker.inline.hpp" 63 #include "memory/generationSpec.hpp" 64 #include "memory/iterator.hpp" 65 #include "memory/referenceProcessor.hpp" 66 #include "oops/oop.inline.hpp" 67 #include "oops/oop.pcgc.inline.hpp" 68 #include "runtime/atomic.inline.hpp" 69 #include "runtime/orderAccess.inline.hpp" 70 #include "runtime/vmThread.hpp" 71 #include "utilities/globalDefinitions.hpp" 72 73 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0; 74 75 // turn it on so that the contents of the young list (scan-only / 76 // to-be-collected) are printed at "strategic" points before / during 77 // / after the collection --- this is useful for debugging 78 #define YOUNG_LIST_VERBOSE 0 79 // CURRENT STATUS 80 // This file is under construction. Search for "FIXME". 81 82 // INVARIANTS/NOTES 83 // 84 // All allocation activity covered by the G1CollectedHeap interface is 85 // serialized by acquiring the HeapLock. This happens in mem_allocate 86 // and allocate_new_tlab, which are the "entry" points to the 87 // allocation code from the rest of the JVM. (Note that this does not 88 // apply to TLAB allocation, which is not part of this interface: it 89 // is done by clients of this interface.) 90 91 // Notes on implementation of parallelism in different tasks. 92 // 93 // G1ParVerifyTask uses heap_region_par_iterate_chunked() for parallelism. 94 // The number of GC workers is passed to heap_region_par_iterate_chunked(). 95 // It does use run_task() which sets _n_workers in the task. 96 // G1ParTask executes g1_process_roots() -> 97 // SharedHeap::process_roots() which calls eventually to 98 // CardTableModRefBS::par_non_clean_card_iterate_work() which uses 99 // SequentialSubTasksDone. SharedHeap::process_roots() also 100 // directly uses SubTasksDone (_process_strong_tasks field in SharedHeap). 101 // 102 103 // Local to this file. 104 105 class RefineCardTableEntryClosure: public CardTableEntryClosure { 106 bool _concurrent; 107 public: 108 RefineCardTableEntryClosure() : _concurrent(true) { } 109 110 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 111 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false); 112 // This path is executed by the concurrent refine or mutator threads, 113 // concurrently, and so we do not care if card_ptr contains references 114 // that point into the collection set. 115 assert(!oops_into_cset, "should be"); 116 117 if (_concurrent && SuspendibleThreadSet::should_yield()) { 118 // Caller will actually yield. 119 return false; 120 } 121 // Otherwise, we finished successfully; return true. 122 return true; 123 } 124 125 void set_concurrent(bool b) { _concurrent = b; } 126 }; 127 128 129 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure { 130 size_t _num_processed; 131 CardTableModRefBS* _ctbs; 132 int _histo[256]; 133 134 public: 135 ClearLoggedCardTableEntryClosure() : 136 _num_processed(0), _ctbs(G1CollectedHeap::heap()->g1_barrier_set()) 137 { 138 for (int i = 0; i < 256; i++) _histo[i] = 0; 139 } 140 141 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 142 unsigned char* ujb = (unsigned char*)card_ptr; 143 int ind = (int)(*ujb); 144 _histo[ind]++; 145 146 *card_ptr = (jbyte)CardTableModRefBS::clean_card_val(); 147 _num_processed++; 148 149 return true; 150 } 151 152 size_t num_processed() { return _num_processed; } 153 154 void print_histo() { 155 gclog_or_tty->print_cr("Card table value histogram:"); 156 for (int i = 0; i < 256; i++) { 157 if (_histo[i] != 0) { 158 gclog_or_tty->print_cr(" %d: %d", i, _histo[i]); 159 } 160 } 161 } 162 }; 163 164 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure { 165 private: 166 size_t _num_processed; 167 168 public: 169 RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { } 170 171 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 172 *card_ptr = CardTableModRefBS::dirty_card_val(); 173 _num_processed++; 174 return true; 175 } 176 177 size_t num_processed() const { return _num_processed; } 178 }; 179 180 YoungList::YoungList(G1CollectedHeap* g1h) : 181 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0), 182 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) { 183 guarantee(check_list_empty(false), "just making sure..."); 184 } 185 186 void YoungList::push_region(HeapRegion *hr) { 187 assert(!hr->is_young(), "should not already be young"); 188 assert(hr->get_next_young_region() == NULL, "cause it should!"); 189 190 hr->set_next_young_region(_head); 191 _head = hr; 192 193 _g1h->g1_policy()->set_region_eden(hr, (int) _length); 194 ++_length; 195 } 196 197 void YoungList::add_survivor_region(HeapRegion* hr) { 198 assert(hr->is_survivor(), "should be flagged as survivor region"); 199 assert(hr->get_next_young_region() == NULL, "cause it should!"); 200 201 hr->set_next_young_region(_survivor_head); 202 if (_survivor_head == NULL) { 203 _survivor_tail = hr; 204 } 205 _survivor_head = hr; 206 ++_survivor_length; 207 } 208 209 void YoungList::empty_list(HeapRegion* list) { 210 while (list != NULL) { 211 HeapRegion* next = list->get_next_young_region(); 212 list->set_next_young_region(NULL); 213 list->uninstall_surv_rate_group(); 214 list->set_not_young(); 215 list = next; 216 } 217 } 218 219 void YoungList::empty_list() { 220 assert(check_list_well_formed(), "young list should be well formed"); 221 222 empty_list(_head); 223 _head = NULL; 224 _length = 0; 225 226 empty_list(_survivor_head); 227 _survivor_head = NULL; 228 _survivor_tail = NULL; 229 _survivor_length = 0; 230 231 _last_sampled_rs_lengths = 0; 232 233 assert(check_list_empty(false), "just making sure..."); 234 } 235 236 bool YoungList::check_list_well_formed() { 237 bool ret = true; 238 239 uint length = 0; 240 HeapRegion* curr = _head; 241 HeapRegion* last = NULL; 242 while (curr != NULL) { 243 if (!curr->is_young()) { 244 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" " 245 "incorrectly tagged (y: %d, surv: %d)", 246 curr->bottom(), curr->end(), 247 curr->is_young(), curr->is_survivor()); 248 ret = false; 249 } 250 ++length; 251 last = curr; 252 curr = curr->get_next_young_region(); 253 } 254 ret = ret && (length == _length); 255 256 if (!ret) { 257 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!"); 258 gclog_or_tty->print_cr("### list has %u entries, _length is %u", 259 length, _length); 260 } 261 262 return ret; 263 } 264 265 bool YoungList::check_list_empty(bool check_sample) { 266 bool ret = true; 267 268 if (_length != 0) { 269 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u", 270 _length); 271 ret = false; 272 } 273 if (check_sample && _last_sampled_rs_lengths != 0) { 274 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths"); 275 ret = false; 276 } 277 if (_head != NULL) { 278 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head"); 279 ret = false; 280 } 281 if (!ret) { 282 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty"); 283 } 284 285 return ret; 286 } 287 288 void 289 YoungList::rs_length_sampling_init() { 290 _sampled_rs_lengths = 0; 291 _curr = _head; 292 } 293 294 bool 295 YoungList::rs_length_sampling_more() { 296 return _curr != NULL; 297 } 298 299 void 300 YoungList::rs_length_sampling_next() { 301 assert( _curr != NULL, "invariant" ); 302 size_t rs_length = _curr->rem_set()->occupied(); 303 304 _sampled_rs_lengths += rs_length; 305 306 // The current region may not yet have been added to the 307 // incremental collection set (it gets added when it is 308 // retired as the current allocation region). 309 if (_curr->in_collection_set()) { 310 // Update the collection set policy information for this region 311 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length); 312 } 313 314 _curr = _curr->get_next_young_region(); 315 if (_curr == NULL) { 316 _last_sampled_rs_lengths = _sampled_rs_lengths; 317 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths); 318 } 319 } 320 321 void 322 YoungList::reset_auxilary_lists() { 323 guarantee( is_empty(), "young list should be empty" ); 324 assert(check_list_well_formed(), "young list should be well formed"); 325 326 // Add survivor regions to SurvRateGroup. 327 _g1h->g1_policy()->note_start_adding_survivor_regions(); 328 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */); 329 330 int young_index_in_cset = 0; 331 for (HeapRegion* curr = _survivor_head; 332 curr != NULL; 333 curr = curr->get_next_young_region()) { 334 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset); 335 336 // The region is a non-empty survivor so let's add it to 337 // the incremental collection set for the next evacuation 338 // pause. 339 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr); 340 young_index_in_cset += 1; 341 } 342 assert((uint) young_index_in_cset == _survivor_length, "post-condition"); 343 _g1h->g1_policy()->note_stop_adding_survivor_regions(); 344 345 _head = _survivor_head; 346 _length = _survivor_length; 347 if (_survivor_head != NULL) { 348 assert(_survivor_tail != NULL, "cause it shouldn't be"); 349 assert(_survivor_length > 0, "invariant"); 350 _survivor_tail->set_next_young_region(NULL); 351 } 352 353 // Don't clear the survivor list handles until the start of 354 // the next evacuation pause - we need it in order to re-tag 355 // the survivor regions from this evacuation pause as 'young' 356 // at the start of the next. 357 358 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */); 359 360 assert(check_list_well_formed(), "young list should be well formed"); 361 } 362 363 void YoungList::print() { 364 HeapRegion* lists[] = {_head, _survivor_head}; 365 const char* names[] = {"YOUNG", "SURVIVOR"}; 366 367 for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) { 368 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]); 369 HeapRegion *curr = lists[list]; 370 if (curr == NULL) 371 gclog_or_tty->print_cr(" empty"); 372 while (curr != NULL) { 373 gclog_or_tty->print_cr(" "HR_FORMAT", P: "PTR_FORMAT "N: "PTR_FORMAT", age: %4d", 374 HR_FORMAT_PARAMS(curr), 375 curr->prev_top_at_mark_start(), 376 curr->next_top_at_mark_start(), 377 curr->age_in_surv_rate_group_cond()); 378 curr = curr->get_next_young_region(); 379 } 380 } 381 382 gclog_or_tty->cr(); 383 } 384 385 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) { 386 OtherRegionsTable::invalidate(start_idx, num_regions); 387 } 388 389 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions) { 390 reset_from_card_cache(start_idx, num_regions); 391 } 392 393 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr) 394 { 395 // Claim the right to put the region on the dirty cards region list 396 // by installing a self pointer. 397 HeapRegion* next = hr->get_next_dirty_cards_region(); 398 if (next == NULL) { 399 HeapRegion* res = (HeapRegion*) 400 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(), 401 NULL); 402 if (res == NULL) { 403 HeapRegion* head; 404 do { 405 // Put the region to the dirty cards region list. 406 head = _dirty_cards_region_list; 407 next = (HeapRegion*) 408 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head); 409 if (next == head) { 410 assert(hr->get_next_dirty_cards_region() == hr, 411 "hr->get_next_dirty_cards_region() != hr"); 412 if (next == NULL) { 413 // The last region in the list points to itself. 414 hr->set_next_dirty_cards_region(hr); 415 } else { 416 hr->set_next_dirty_cards_region(next); 417 } 418 } 419 } while (next != head); 420 } 421 } 422 } 423 424 HeapRegion* G1CollectedHeap::pop_dirty_cards_region() 425 { 426 HeapRegion* head; 427 HeapRegion* hr; 428 do { 429 head = _dirty_cards_region_list; 430 if (head == NULL) { 431 return NULL; 432 } 433 HeapRegion* new_head = head->get_next_dirty_cards_region(); 434 if (head == new_head) { 435 // The last region. 436 new_head = NULL; 437 } 438 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list, 439 head); 440 } while (hr != head); 441 assert(hr != NULL, "invariant"); 442 hr->set_next_dirty_cards_region(NULL); 443 return hr; 444 } 445 446 #ifdef ASSERT 447 // A region is added to the collection set as it is retired 448 // so an address p can point to a region which will be in the 449 // collection set but has not yet been retired. This method 450 // therefore is only accurate during a GC pause after all 451 // regions have been retired. It is used for debugging 452 // to check if an nmethod has references to objects that can 453 // be move during a partial collection. Though it can be 454 // inaccurate, it is sufficient for G1 because the conservative 455 // implementation of is_scavengable() for G1 will indicate that 456 // all nmethods must be scanned during a partial collection. 457 bool G1CollectedHeap::is_in_partial_collection(const void* p) { 458 if (p == NULL) { 459 return false; 460 } 461 return heap_region_containing(p)->in_collection_set(); 462 } 463 #endif 464 465 // Returns true if the reference points to an object that 466 // can move in an incremental collection. 467 bool G1CollectedHeap::is_scavengable(const void* p) { 468 HeapRegion* hr = heap_region_containing(p); 469 return !hr->isHumongous(); 470 } 471 472 void G1CollectedHeap::check_ct_logs_at_safepoint() { 473 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 474 CardTableModRefBS* ct_bs = g1_barrier_set(); 475 476 // Count the dirty cards at the start. 477 CountNonCleanMemRegionClosure count1(this); 478 ct_bs->mod_card_iterate(&count1); 479 int orig_count = count1.n(); 480 481 // First clear the logged cards. 482 ClearLoggedCardTableEntryClosure clear; 483 dcqs.apply_closure_to_all_completed_buffers(&clear); 484 dcqs.iterate_closure_all_threads(&clear, false); 485 clear.print_histo(); 486 487 // Now ensure that there's no dirty cards. 488 CountNonCleanMemRegionClosure count2(this); 489 ct_bs->mod_card_iterate(&count2); 490 if (count2.n() != 0) { 491 gclog_or_tty->print_cr("Card table has %d entries; %d originally", 492 count2.n(), orig_count); 493 } 494 guarantee(count2.n() == 0, "Card table should be clean."); 495 496 RedirtyLoggedCardTableEntryClosure redirty; 497 dcqs.apply_closure_to_all_completed_buffers(&redirty); 498 dcqs.iterate_closure_all_threads(&redirty, false); 499 gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.", 500 clear.num_processed(), orig_count); 501 guarantee(redirty.num_processed() == clear.num_processed(), 502 err_msg("Redirtied "SIZE_FORMAT" cards, bug cleared "SIZE_FORMAT, 503 redirty.num_processed(), clear.num_processed())); 504 505 CountNonCleanMemRegionClosure count3(this); 506 ct_bs->mod_card_iterate(&count3); 507 if (count3.n() != orig_count) { 508 gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.", 509 orig_count, count3.n()); 510 guarantee(count3.n() >= orig_count, "Should have restored them all."); 511 } 512 } 513 514 // Private class members. 515 516 G1CollectedHeap* G1CollectedHeap::_g1h; 517 518 // Private methods. 519 520 HeapRegion* 521 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) { 522 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 523 while (!_secondary_free_list.is_empty() || free_regions_coming()) { 524 if (!_secondary_free_list.is_empty()) { 525 if (G1ConcRegionFreeingVerbose) { 526 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 527 "secondary_free_list has %u entries", 528 _secondary_free_list.length()); 529 } 530 // It looks as if there are free regions available on the 531 // secondary_free_list. Let's move them to the free_list and try 532 // again to allocate from it. 533 append_secondary_free_list(); 534 535 assert(_hrs.num_free_regions() > 0, "if the secondary_free_list was not " 536 "empty we should have moved at least one entry to the free_list"); 537 HeapRegion* res = _hrs.allocate_free_region(is_old); 538 if (G1ConcRegionFreeingVerbose) { 539 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 540 "allocated "HR_FORMAT" from secondary_free_list", 541 HR_FORMAT_PARAMS(res)); 542 } 543 return res; 544 } 545 546 // Wait here until we get notified either when (a) there are no 547 // more free regions coming or (b) some regions have been moved on 548 // the secondary_free_list. 549 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 550 } 551 552 if (G1ConcRegionFreeingVerbose) { 553 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 554 "could not allocate from secondary_free_list"); 555 } 556 return NULL; 557 } 558 559 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) { 560 assert(!isHumongous(word_size) || word_size <= HeapRegion::GrainWords, 561 "the only time we use this to allocate a humongous region is " 562 "when we are allocating a single humongous region"); 563 564 HeapRegion* res; 565 if (G1StressConcRegionFreeing) { 566 if (!_secondary_free_list.is_empty()) { 567 if (G1ConcRegionFreeingVerbose) { 568 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 569 "forced to look at the secondary_free_list"); 570 } 571 res = new_region_try_secondary_free_list(is_old); 572 if (res != NULL) { 573 return res; 574 } 575 } 576 } 577 578 res = _hrs.allocate_free_region(is_old); 579 580 if (res == NULL) { 581 if (G1ConcRegionFreeingVerbose) { 582 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 583 "res == NULL, trying the secondary_free_list"); 584 } 585 res = new_region_try_secondary_free_list(is_old); 586 } 587 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) { 588 // Currently, only attempts to allocate GC alloc regions set 589 // do_expand to true. So, we should only reach here during a 590 // safepoint. If this assumption changes we might have to 591 // reconsider the use of _expand_heap_after_alloc_failure. 592 assert(SafepointSynchronize::is_at_safepoint(), "invariant"); 593 594 ergo_verbose1(ErgoHeapSizing, 595 "attempt heap expansion", 596 ergo_format_reason("region allocation request failed") 597 ergo_format_byte("allocation request"), 598 word_size * HeapWordSize); 599 if (expand(word_size * HeapWordSize)) { 600 // Given that expand() succeeded in expanding the heap, and we 601 // always expand the heap by an amount aligned to the heap 602 // region size, the free list should in theory not be empty. 603 // In either case allocate_free_region() will check for NULL. 604 res = _hrs.allocate_free_region(is_old); 605 } else { 606 _expand_heap_after_alloc_failure = false; 607 } 608 } 609 return res; 610 } 611 612 HeapWord* 613 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first, 614 uint num_regions, 615 size_t word_size) { 616 assert(first != G1_NO_HRS_INDEX, "pre-condition"); 617 assert(isHumongous(word_size), "word_size should be humongous"); 618 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition"); 619 620 // Index of last region in the series + 1. 621 uint last = first + num_regions; 622 623 // We need to initialize the region(s) we just discovered. This is 624 // a bit tricky given that it can happen concurrently with 625 // refinement threads refining cards on these regions and 626 // potentially wanting to refine the BOT as they are scanning 627 // those cards (this can happen shortly after a cleanup; see CR 628 // 6991377). So we have to set up the region(s) carefully and in 629 // a specific order. 630 631 // The word size sum of all the regions we will allocate. 632 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords; 633 assert(word_size <= word_size_sum, "sanity"); 634 635 // This will be the "starts humongous" region. 636 HeapRegion* first_hr = region_at(first); 637 // The header of the new object will be placed at the bottom of 638 // the first region. 639 HeapWord* new_obj = first_hr->bottom(); 640 // This will be the new end of the first region in the series that 641 // should also match the end of the last region in the series. 642 HeapWord* new_end = new_obj + word_size_sum; 643 // This will be the new top of the first region that will reflect 644 // this allocation. 645 HeapWord* new_top = new_obj + word_size; 646 647 // First, we need to zero the header of the space that we will be 648 // allocating. When we update top further down, some refinement 649 // threads might try to scan the region. By zeroing the header we 650 // ensure that any thread that will try to scan the region will 651 // come across the zero klass word and bail out. 652 // 653 // NOTE: It would not have been correct to have used 654 // CollectedHeap::fill_with_object() and make the space look like 655 // an int array. The thread that is doing the allocation will 656 // later update the object header to a potentially different array 657 // type and, for a very short period of time, the klass and length 658 // fields will be inconsistent. This could cause a refinement 659 // thread to calculate the object size incorrectly. 660 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0); 661 662 // We will set up the first region as "starts humongous". This 663 // will also update the BOT covering all the regions to reflect 664 // that there is a single object that starts at the bottom of the 665 // first region. 666 first_hr->set_startsHumongous(new_top, new_end); 667 668 // Then, if there are any, we will set up the "continues 669 // humongous" regions. 670 HeapRegion* hr = NULL; 671 for (uint i = first + 1; i < last; ++i) { 672 hr = region_at(i); 673 hr->set_continuesHumongous(first_hr); 674 } 675 // If we have "continues humongous" regions (hr != NULL), then the 676 // end of the last one should match new_end. 677 assert(hr == NULL || hr->end() == new_end, "sanity"); 678 679 // Up to this point no concurrent thread would have been able to 680 // do any scanning on any region in this series. All the top 681 // fields still point to bottom, so the intersection between 682 // [bottom,top] and [card_start,card_end] will be empty. Before we 683 // update the top fields, we'll do a storestore to make sure that 684 // no thread sees the update to top before the zeroing of the 685 // object header and the BOT initialization. 686 OrderAccess::storestore(); 687 688 // Now that the BOT and the object header have been initialized, 689 // we can update top of the "starts humongous" region. 690 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(), 691 "new_top should be in this region"); 692 first_hr->set_top(new_top); 693 if (_hr_printer.is_active()) { 694 HeapWord* bottom = first_hr->bottom(); 695 HeapWord* end = first_hr->orig_end(); 696 if ((first + 1) == last) { 697 // the series has a single humongous region 698 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top); 699 } else { 700 // the series has more than one humongous regions 701 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end); 702 } 703 } 704 705 // Now, we will update the top fields of the "continues humongous" 706 // regions. The reason we need to do this is that, otherwise, 707 // these regions would look empty and this will confuse parts of 708 // G1. For example, the code that looks for a consecutive number 709 // of empty regions will consider them empty and try to 710 // re-allocate them. We can extend is_empty() to also include 711 // !continuesHumongous(), but it is easier to just update the top 712 // fields here. The way we set top for all regions (i.e., top == 713 // end for all regions but the last one, top == new_top for the 714 // last one) is actually used when we will free up the humongous 715 // region in free_humongous_region(). 716 hr = NULL; 717 for (uint i = first + 1; i < last; ++i) { 718 hr = region_at(i); 719 if ((i + 1) == last) { 720 // last continues humongous region 721 assert(hr->bottom() < new_top && new_top <= hr->end(), 722 "new_top should fall on this region"); 723 hr->set_top(new_top); 724 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top); 725 } else { 726 // not last one 727 assert(new_top > hr->end(), "new_top should be above this region"); 728 hr->set_top(hr->end()); 729 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end()); 730 } 731 } 732 // If we have continues humongous regions (hr != NULL), then the 733 // end of the last one should match new_end and its top should 734 // match new_top. 735 assert(hr == NULL || 736 (hr->end() == new_end && hr->top() == new_top), "sanity"); 737 check_bitmaps("Humongous Region Allocation", first_hr); 738 739 assert(first_hr->used() == word_size * HeapWordSize, "invariant"); 740 _summary_bytes_used += first_hr->used(); 741 _humongous_set.add(first_hr); 742 743 return new_obj; 744 } 745 746 // If could fit into free regions w/o expansion, try. 747 // Otherwise, if can expand, do so. 748 // Otherwise, if using ex regions might help, try with ex given back. 749 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) { 750 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 751 752 verify_region_sets_optional(); 753 754 uint first = G1_NO_HRS_INDEX; 755 uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords); 756 757 if (obj_regions == 1) { 758 // Only one region to allocate, try to use a fast path by directly allocating 759 // from the free lists. Do not try to expand here, we will potentially do that 760 // later. 761 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */); 762 if (hr != NULL) { 763 first = hr->hrs_index(); 764 } 765 } else { 766 // We can't allocate humongous regions spanning more than one region while 767 // cleanupComplete() is running, since some of the regions we find to be 768 // empty might not yet be added to the free list. It is not straightforward 769 // to know in which list they are on so that we can remove them. We only 770 // need to do this if we need to allocate more than one region to satisfy the 771 // current humongous allocation request. If we are only allocating one region 772 // we use the one-region region allocation code (see above), that already 773 // potentially waits for regions from the secondary free list. 774 wait_while_free_regions_coming(); 775 append_secondary_free_list_if_not_empty_with_lock(); 776 777 // Policy: Try only empty regions (i.e. already committed first). Maybe we 778 // are lucky enough to find some. 779 first = _hrs.find_contiguous_only_empty(obj_regions); 780 if (first != G1_NO_HRS_INDEX) { 781 _hrs.allocate_free_regions_starting_at(first, obj_regions); 782 } 783 } 784 785 if (first == G1_NO_HRS_INDEX) { 786 // Policy: We could not find enough regions for the humongous object in the 787 // free list. Look through the heap to find a mix of free and uncommitted regions. 788 // If so, try expansion. 789 first = _hrs.find_contiguous_empty_or_unavailable(obj_regions); 790 if (first != G1_NO_HRS_INDEX) { 791 // We found something. Make sure these regions are committed, i.e. expand 792 // the heap. Alternatively we could do a defragmentation GC. 793 ergo_verbose1(ErgoHeapSizing, 794 "attempt heap expansion", 795 ergo_format_reason("humongous allocation request failed") 796 ergo_format_byte("allocation request"), 797 word_size * HeapWordSize); 798 799 _hrs.expand_at(first, obj_regions); 800 g1_policy()->record_new_heap_size(num_regions()); 801 802 #ifdef ASSERT 803 for (uint i = first; i < first + obj_regions; ++i) { 804 HeapRegion* hr = region_at(i); 805 assert(hr->is_empty(), "sanity"); 806 assert(is_on_master_free_list(hr), "sanity"); 807 } 808 #endif 809 _hrs.allocate_free_regions_starting_at(first, obj_regions); 810 } else { 811 // Policy: Potentially trigger a defragmentation GC. 812 } 813 } 814 815 HeapWord* result = NULL; 816 if (first != G1_NO_HRS_INDEX) { 817 result = humongous_obj_allocate_initialize_regions(first, obj_regions, word_size); 818 assert(result != NULL, "it should always return a valid result"); 819 820 // A successful humongous object allocation changes the used space 821 // information of the old generation so we need to recalculate the 822 // sizes and update the jstat counters here. 823 g1mm()->update_sizes(); 824 } 825 826 verify_region_sets_optional(); 827 828 return result; 829 } 830 831 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) { 832 assert_heap_not_locked_and_not_at_safepoint(); 833 assert(!isHumongous(word_size), "we do not allow humongous TLABs"); 834 835 unsigned int dummy_gc_count_before; 836 int dummy_gclocker_retry_count = 0; 837 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count); 838 } 839 840 HeapWord* 841 G1CollectedHeap::mem_allocate(size_t word_size, 842 bool* gc_overhead_limit_was_exceeded) { 843 assert_heap_not_locked_and_not_at_safepoint(); 844 845 // Loop until the allocation is satisfied, or unsatisfied after GC. 846 for (int try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 847 unsigned int gc_count_before; 848 849 HeapWord* result = NULL; 850 if (!isHumongous(word_size)) { 851 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count); 852 } else { 853 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count); 854 } 855 if (result != NULL) { 856 return result; 857 } 858 859 // Create the garbage collection operation... 860 VM_G1CollectForAllocation op(gc_count_before, word_size); 861 // ...and get the VM thread to execute it. 862 VMThread::execute(&op); 863 864 if (op.prologue_succeeded() && op.pause_succeeded()) { 865 // If the operation was successful we'll return the result even 866 // if it is NULL. If the allocation attempt failed immediately 867 // after a Full GC, it's unlikely we'll be able to allocate now. 868 HeapWord* result = op.result(); 869 if (result != NULL && !isHumongous(word_size)) { 870 // Allocations that take place on VM operations do not do any 871 // card dirtying and we have to do it here. We only have to do 872 // this for non-humongous allocations, though. 873 dirty_young_block(result, word_size); 874 } 875 return result; 876 } else { 877 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 878 return NULL; 879 } 880 assert(op.result() == NULL, 881 "the result should be NULL if the VM op did not succeed"); 882 } 883 884 // Give a warning if we seem to be looping forever. 885 if ((QueuedAllocationWarningCount > 0) && 886 (try_count % QueuedAllocationWarningCount == 0)) { 887 warning("G1CollectedHeap::mem_allocate retries %d times", try_count); 888 } 889 } 890 891 ShouldNotReachHere(); 892 return NULL; 893 } 894 895 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size, 896 unsigned int *gc_count_before_ret, 897 int* gclocker_retry_count_ret) { 898 // Make sure you read the note in attempt_allocation_humongous(). 899 900 assert_heap_not_locked_and_not_at_safepoint(); 901 assert(!isHumongous(word_size), "attempt_allocation_slow() should not " 902 "be called for humongous allocation requests"); 903 904 // We should only get here after the first-level allocation attempt 905 // (attempt_allocation()) failed to allocate. 906 907 // We will loop until a) we manage to successfully perform the 908 // allocation or b) we successfully schedule a collection which 909 // fails to perform the allocation. b) is the only case when we'll 910 // return NULL. 911 HeapWord* result = NULL; 912 for (int try_count = 1; /* we'll return */; try_count += 1) { 913 bool should_try_gc; 914 unsigned int gc_count_before; 915 916 { 917 MutexLockerEx x(Heap_lock); 918 919 result = _mutator_alloc_region.attempt_allocation_locked(word_size, 920 false /* bot_updates */); 921 if (result != NULL) { 922 return result; 923 } 924 925 // If we reach here, attempt_allocation_locked() above failed to 926 // allocate a new region. So the mutator alloc region should be NULL. 927 assert(_mutator_alloc_region.get() == NULL, "only way to get here"); 928 929 if (GC_locker::is_active_and_needs_gc()) { 930 if (g1_policy()->can_expand_young_list()) { 931 // No need for an ergo verbose message here, 932 // can_expand_young_list() does this when it returns true. 933 result = _mutator_alloc_region.attempt_allocation_force(word_size, 934 false /* bot_updates */); 935 if (result != NULL) { 936 return result; 937 } 938 } 939 should_try_gc = false; 940 } else { 941 // The GCLocker may not be active but the GCLocker initiated 942 // GC may not yet have been performed (GCLocker::needs_gc() 943 // returns true). In this case we do not try this GC and 944 // wait until the GCLocker initiated GC is performed, and 945 // then retry the allocation. 946 if (GC_locker::needs_gc()) { 947 should_try_gc = false; 948 } else { 949 // Read the GC count while still holding the Heap_lock. 950 gc_count_before = total_collections(); 951 should_try_gc = true; 952 } 953 } 954 } 955 956 if (should_try_gc) { 957 bool succeeded; 958 result = do_collection_pause(word_size, gc_count_before, &succeeded, 959 GCCause::_g1_inc_collection_pause); 960 if (result != NULL) { 961 assert(succeeded, "only way to get back a non-NULL result"); 962 return result; 963 } 964 965 if (succeeded) { 966 // If we get here we successfully scheduled a collection which 967 // failed to allocate. No point in trying to allocate 968 // further. We'll just return NULL. 969 MutexLockerEx x(Heap_lock); 970 *gc_count_before_ret = total_collections(); 971 return NULL; 972 } 973 } else { 974 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { 975 MutexLockerEx x(Heap_lock); 976 *gc_count_before_ret = total_collections(); 977 return NULL; 978 } 979 // The GCLocker is either active or the GCLocker initiated 980 // GC has not yet been performed. Stall until it is and 981 // then retry the allocation. 982 GC_locker::stall_until_clear(); 983 (*gclocker_retry_count_ret) += 1; 984 } 985 986 // We can reach here if we were unsuccessful in scheduling a 987 // collection (because another thread beat us to it) or if we were 988 // stalled due to the GC locker. In either can we should retry the 989 // allocation attempt in case another thread successfully 990 // performed a collection and reclaimed enough space. We do the 991 // first attempt (without holding the Heap_lock) here and the 992 // follow-on attempt will be at the start of the next loop 993 // iteration (after taking the Heap_lock). 994 result = _mutator_alloc_region.attempt_allocation(word_size, 995 false /* bot_updates */); 996 if (result != NULL) { 997 return result; 998 } 999 1000 // Give a warning if we seem to be looping forever. 1001 if ((QueuedAllocationWarningCount > 0) && 1002 (try_count % QueuedAllocationWarningCount == 0)) { 1003 warning("G1CollectedHeap::attempt_allocation_slow() " 1004 "retries %d times", try_count); 1005 } 1006 } 1007 1008 ShouldNotReachHere(); 1009 return NULL; 1010 } 1011 1012 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size, 1013 unsigned int * gc_count_before_ret, 1014 int* gclocker_retry_count_ret) { 1015 // The structure of this method has a lot of similarities to 1016 // attempt_allocation_slow(). The reason these two were not merged 1017 // into a single one is that such a method would require several "if 1018 // allocation is not humongous do this, otherwise do that" 1019 // conditional paths which would obscure its flow. In fact, an early 1020 // version of this code did use a unified method which was harder to 1021 // follow and, as a result, it had subtle bugs that were hard to 1022 // track down. So keeping these two methods separate allows each to 1023 // be more readable. It will be good to keep these two in sync as 1024 // much as possible. 1025 1026 assert_heap_not_locked_and_not_at_safepoint(); 1027 assert(isHumongous(word_size), "attempt_allocation_humongous() " 1028 "should only be called for humongous allocations"); 1029 1030 // Humongous objects can exhaust the heap quickly, so we should check if we 1031 // need to start a marking cycle at each humongous object allocation. We do 1032 // the check before we do the actual allocation. The reason for doing it 1033 // before the allocation is that we avoid having to keep track of the newly 1034 // allocated memory while we do a GC. 1035 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation", 1036 word_size)) { 1037 collect(GCCause::_g1_humongous_allocation); 1038 } 1039 1040 // We will loop until a) we manage to successfully perform the 1041 // allocation or b) we successfully schedule a collection which 1042 // fails to perform the allocation. b) is the only case when we'll 1043 // return NULL. 1044 HeapWord* result = NULL; 1045 for (int try_count = 1; /* we'll return */; try_count += 1) { 1046 bool should_try_gc; 1047 unsigned int gc_count_before; 1048 1049 { 1050 MutexLockerEx x(Heap_lock); 1051 1052 // Given that humongous objects are not allocated in young 1053 // regions, we'll first try to do the allocation without doing a 1054 // collection hoping that there's enough space in the heap. 1055 result = humongous_obj_allocate(word_size); 1056 if (result != NULL) { 1057 return result; 1058 } 1059 1060 if (GC_locker::is_active_and_needs_gc()) { 1061 should_try_gc = false; 1062 } else { 1063 // The GCLocker may not be active but the GCLocker initiated 1064 // GC may not yet have been performed (GCLocker::needs_gc() 1065 // returns true). In this case we do not try this GC and 1066 // wait until the GCLocker initiated GC is performed, and 1067 // then retry the allocation. 1068 if (GC_locker::needs_gc()) { 1069 should_try_gc = false; 1070 } else { 1071 // Read the GC count while still holding the Heap_lock. 1072 gc_count_before = total_collections(); 1073 should_try_gc = true; 1074 } 1075 } 1076 } 1077 1078 if (should_try_gc) { 1079 // If we failed to allocate the humongous object, we should try to 1080 // do a collection pause (if we're allowed) in case it reclaims 1081 // enough space for the allocation to succeed after the pause. 1082 1083 bool succeeded; 1084 result = do_collection_pause(word_size, gc_count_before, &succeeded, 1085 GCCause::_g1_humongous_allocation); 1086 if (result != NULL) { 1087 assert(succeeded, "only way to get back a non-NULL result"); 1088 return result; 1089 } 1090 1091 if (succeeded) { 1092 // If we get here we successfully scheduled a collection which 1093 // failed to allocate. No point in trying to allocate 1094 // further. We'll just return NULL. 1095 MutexLockerEx x(Heap_lock); 1096 *gc_count_before_ret = total_collections(); 1097 return NULL; 1098 } 1099 } else { 1100 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { 1101 MutexLockerEx x(Heap_lock); 1102 *gc_count_before_ret = total_collections(); 1103 return NULL; 1104 } 1105 // The GCLocker is either active or the GCLocker initiated 1106 // GC has not yet been performed. Stall until it is and 1107 // then retry the allocation. 1108 GC_locker::stall_until_clear(); 1109 (*gclocker_retry_count_ret) += 1; 1110 } 1111 1112 // We can reach here if we were unsuccessful in scheduling a 1113 // collection (because another thread beat us to it) or if we were 1114 // stalled due to the GC locker. In either can we should retry the 1115 // allocation attempt in case another thread successfully 1116 // performed a collection and reclaimed enough space. Give a 1117 // warning if we seem to be looping forever. 1118 1119 if ((QueuedAllocationWarningCount > 0) && 1120 (try_count % QueuedAllocationWarningCount == 0)) { 1121 warning("G1CollectedHeap::attempt_allocation_humongous() " 1122 "retries %d times", try_count); 1123 } 1124 } 1125 1126 ShouldNotReachHere(); 1127 return NULL; 1128 } 1129 1130 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size, 1131 bool expect_null_mutator_alloc_region) { 1132 assert_at_safepoint(true /* should_be_vm_thread */); 1133 assert(_mutator_alloc_region.get() == NULL || 1134 !expect_null_mutator_alloc_region, 1135 "the current alloc region was unexpectedly found to be non-NULL"); 1136 1137 if (!isHumongous(word_size)) { 1138 return _mutator_alloc_region.attempt_allocation_locked(word_size, 1139 false /* bot_updates */); 1140 } else { 1141 HeapWord* result = humongous_obj_allocate(word_size); 1142 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) { 1143 g1_policy()->set_initiate_conc_mark_if_possible(); 1144 } 1145 return result; 1146 } 1147 1148 ShouldNotReachHere(); 1149 } 1150 1151 class PostMCRemSetClearClosure: public HeapRegionClosure { 1152 G1CollectedHeap* _g1h; 1153 ModRefBarrierSet* _mr_bs; 1154 public: 1155 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) : 1156 _g1h(g1h), _mr_bs(mr_bs) {} 1157 1158 bool doHeapRegion(HeapRegion* r) { 1159 HeapRegionRemSet* hrrs = r->rem_set(); 1160 1161 if (r->continuesHumongous()) { 1162 // We'll assert that the strong code root list and RSet is empty 1163 assert(hrrs->strong_code_roots_list_length() == 0, "sanity"); 1164 assert(hrrs->occupied() == 0, "RSet should be empty"); 1165 return false; 1166 } 1167 1168 _g1h->reset_gc_time_stamps(r); 1169 hrrs->clear(); 1170 // You might think here that we could clear just the cards 1171 // corresponding to the used region. But no: if we leave a dirty card 1172 // in a region we might allocate into, then it would prevent that card 1173 // from being enqueued, and cause it to be missed. 1174 // Re: the performance cost: we shouldn't be doing full GC anyway! 1175 _mr_bs->clear(MemRegion(r->bottom(), r->end())); 1176 1177 return false; 1178 } 1179 }; 1180 1181 void G1CollectedHeap::clear_rsets_post_compaction() { 1182 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set()); 1183 heap_region_iterate(&rs_clear); 1184 } 1185 1186 class RebuildRSOutOfRegionClosure: public HeapRegionClosure { 1187 G1CollectedHeap* _g1h; 1188 UpdateRSOopClosure _cl; 1189 int _worker_i; 1190 public: 1191 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) : 1192 _cl(g1->g1_rem_set(), worker_i), 1193 _worker_i(worker_i), 1194 _g1h(g1) 1195 { } 1196 1197 bool doHeapRegion(HeapRegion* r) { 1198 if (!r->continuesHumongous()) { 1199 _cl.set_from(r); 1200 r->oop_iterate(&_cl); 1201 } 1202 return false; 1203 } 1204 }; 1205 1206 class ParRebuildRSTask: public AbstractGangTask { 1207 G1CollectedHeap* _g1; 1208 public: 1209 ParRebuildRSTask(G1CollectedHeap* g1) 1210 : AbstractGangTask("ParRebuildRSTask"), 1211 _g1(g1) 1212 { } 1213 1214 void work(uint worker_id) { 1215 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id); 1216 _g1->heap_region_par_iterate_chunked(&rebuild_rs, worker_id, 1217 _g1->workers()->active_workers(), 1218 HeapRegion::RebuildRSClaimValue); 1219 } 1220 }; 1221 1222 class PostCompactionPrinterClosure: public HeapRegionClosure { 1223 private: 1224 G1HRPrinter* _hr_printer; 1225 public: 1226 bool doHeapRegion(HeapRegion* hr) { 1227 assert(!hr->is_young(), "not expecting to find young regions"); 1228 // We only generate output for non-empty regions. 1229 if (!hr->is_empty()) { 1230 if (!hr->isHumongous()) { 1231 _hr_printer->post_compaction(hr, G1HRPrinter::Old); 1232 } else if (hr->startsHumongous()) { 1233 if (hr->region_num() == 1) { 1234 // single humongous region 1235 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous); 1236 } else { 1237 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous); 1238 } 1239 } else { 1240 assert(hr->continuesHumongous(), "only way to get here"); 1241 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous); 1242 } 1243 } 1244 return false; 1245 } 1246 1247 PostCompactionPrinterClosure(G1HRPrinter* hr_printer) 1248 : _hr_printer(hr_printer) { } 1249 }; 1250 1251 void G1CollectedHeap::print_hrs_post_compaction() { 1252 PostCompactionPrinterClosure cl(hr_printer()); 1253 heap_region_iterate(&cl); 1254 } 1255 1256 bool G1CollectedHeap::do_collection(bool explicit_gc, 1257 bool clear_all_soft_refs, 1258 size_t word_size) { 1259 assert_at_safepoint(true /* should_be_vm_thread */); 1260 1261 if (GC_locker::check_active_before_gc()) { 1262 return false; 1263 } 1264 1265 STWGCTimer* gc_timer = G1MarkSweep::gc_timer(); 1266 gc_timer->register_gc_start(); 1267 1268 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer(); 1269 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start()); 1270 1271 SvcGCMarker sgcm(SvcGCMarker::FULL); 1272 ResourceMark rm; 1273 1274 print_heap_before_gc(); 1275 trace_heap_before_gc(gc_tracer); 1276 1277 size_t metadata_prev_used = MetaspaceAux::used_bytes(); 1278 1279 verify_region_sets_optional(); 1280 1281 const bool do_clear_all_soft_refs = clear_all_soft_refs || 1282 collector_policy()->should_clear_all_soft_refs(); 1283 1284 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy()); 1285 1286 { 1287 IsGCActiveMark x; 1288 1289 // Timing 1290 assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant"); 1291 gclog_or_tty->date_stamp(G1Log::fine() && PrintGCDateStamps); 1292 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty); 1293 1294 { 1295 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL, gc_tracer->gc_id()); 1296 TraceCollectorStats tcs(g1mm()->full_collection_counters()); 1297 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause()); 1298 1299 double start = os::elapsedTime(); 1300 g1_policy()->record_full_collection_start(); 1301 1302 // Note: When we have a more flexible GC logging framework that 1303 // allows us to add optional attributes to a GC log record we 1304 // could consider timing and reporting how long we wait in the 1305 // following two methods. 1306 wait_while_free_regions_coming(); 1307 // If we start the compaction before the CM threads finish 1308 // scanning the root regions we might trip them over as we'll 1309 // be moving objects / updating references. So let's wait until 1310 // they are done. By telling them to abort, they should complete 1311 // early. 1312 _cm->root_regions()->abort(); 1313 _cm->root_regions()->wait_until_scan_finished(); 1314 append_secondary_free_list_if_not_empty_with_lock(); 1315 1316 gc_prologue(true); 1317 increment_total_collections(true /* full gc */); 1318 increment_old_marking_cycles_started(); 1319 1320 assert(used() == recalculate_used(), "Should be equal"); 1321 1322 verify_before_gc(); 1323 1324 check_bitmaps("Full GC Start"); 1325 pre_full_gc_dump(gc_timer); 1326 1327 COMPILER2_PRESENT(DerivedPointerTable::clear()); 1328 1329 // Disable discovery and empty the discovered lists 1330 // for the CM ref processor. 1331 ref_processor_cm()->disable_discovery(); 1332 ref_processor_cm()->abandon_partial_discovery(); 1333 ref_processor_cm()->verify_no_references_recorded(); 1334 1335 // Abandon current iterations of concurrent marking and concurrent 1336 // refinement, if any are in progress. We have to do this before 1337 // wait_until_scan_finished() below. 1338 concurrent_mark()->abort(); 1339 1340 // Make sure we'll choose a new allocation region afterwards. 1341 release_mutator_alloc_region(); 1342 abandon_gc_alloc_regions(); 1343 g1_rem_set()->cleanupHRRS(); 1344 1345 // We should call this after we retire any currently active alloc 1346 // regions so that all the ALLOC / RETIRE events are generated 1347 // before the start GC event. 1348 _hr_printer.start_gc(true /* full */, (size_t) total_collections()); 1349 1350 // We may have added regions to the current incremental collection 1351 // set between the last GC or pause and now. We need to clear the 1352 // incremental collection set and then start rebuilding it afresh 1353 // after this full GC. 1354 abandon_collection_set(g1_policy()->inc_cset_head()); 1355 g1_policy()->clear_incremental_cset(); 1356 g1_policy()->stop_incremental_cset_building(); 1357 1358 tear_down_region_sets(false /* free_list_only */); 1359 g1_policy()->set_gcs_are_young(true); 1360 1361 // See the comments in g1CollectedHeap.hpp and 1362 // G1CollectedHeap::ref_processing_init() about 1363 // how reference processing currently works in G1. 1364 1365 // Temporarily make discovery by the STW ref processor single threaded (non-MT). 1366 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false); 1367 1368 // Temporarily clear the STW ref processor's _is_alive_non_header field. 1369 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL); 1370 1371 ref_processor_stw()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/); 1372 ref_processor_stw()->setup_policy(do_clear_all_soft_refs); 1373 1374 // Do collection work 1375 { 1376 HandleMark hm; // Discard invalid handles created during gc 1377 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs); 1378 } 1379 1380 assert(num_free_regions() == 0, "we should not have added any free regions"); 1381 rebuild_region_sets(false /* free_list_only */); 1382 1383 // Enqueue any discovered reference objects that have 1384 // not been removed from the discovered lists. 1385 ref_processor_stw()->enqueue_discovered_references(); 1386 1387 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 1388 1389 MemoryService::track_memory_usage(); 1390 1391 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 1392 ref_processor_stw()->verify_no_references_recorded(); 1393 1394 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 1395 ClassLoaderDataGraph::purge(); 1396 MetaspaceAux::verify_metrics(); 1397 1398 // Note: since we've just done a full GC, concurrent 1399 // marking is no longer active. Therefore we need not 1400 // re-enable reference discovery for the CM ref processor. 1401 // That will be done at the start of the next marking cycle. 1402 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition"); 1403 ref_processor_cm()->verify_no_references_recorded(); 1404 1405 reset_gc_time_stamp(); 1406 // Since everything potentially moved, we will clear all remembered 1407 // sets, and clear all cards. Later we will rebuild remembered 1408 // sets. We will also reset the GC time stamps of the regions. 1409 clear_rsets_post_compaction(); 1410 check_gc_time_stamps(); 1411 1412 // Resize the heap if necessary. 1413 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size); 1414 1415 if (_hr_printer.is_active()) { 1416 // We should do this after we potentially resize the heap so 1417 // that all the COMMIT / UNCOMMIT events are generated before 1418 // the end GC event. 1419 1420 print_hrs_post_compaction(); 1421 _hr_printer.end_gc(true /* full */, (size_t) total_collections()); 1422 } 1423 1424 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 1425 if (hot_card_cache->use_cache()) { 1426 hot_card_cache->reset_card_counts(); 1427 hot_card_cache->reset_hot_cache(); 1428 } 1429 1430 // Rebuild remembered sets of all regions. 1431 if (G1CollectedHeap::use_parallel_gc_threads()) { 1432 uint n_workers = 1433 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 1434 workers()->active_workers(), 1435 Threads::number_of_non_daemon_threads()); 1436 assert(UseDynamicNumberOfGCThreads || 1437 n_workers == workers()->total_workers(), 1438 "If not dynamic should be using all the workers"); 1439 workers()->set_active_workers(n_workers); 1440 // Set parallel threads in the heap (_n_par_threads) only 1441 // before a parallel phase and always reset it to 0 after 1442 // the phase so that the number of parallel threads does 1443 // no get carried forward to a serial phase where there 1444 // may be code that is "possibly_parallel". 1445 set_par_threads(n_workers); 1446 1447 ParRebuildRSTask rebuild_rs_task(this); 1448 assert(check_heap_region_claim_values( 1449 HeapRegion::InitialClaimValue), "sanity check"); 1450 assert(UseDynamicNumberOfGCThreads || 1451 workers()->active_workers() == workers()->total_workers(), 1452 "Unless dynamic should use total workers"); 1453 // Use the most recent number of active workers 1454 assert(workers()->active_workers() > 0, 1455 "Active workers not properly set"); 1456 set_par_threads(workers()->active_workers()); 1457 workers()->run_task(&rebuild_rs_task); 1458 set_par_threads(0); 1459 assert(check_heap_region_claim_values( 1460 HeapRegion::RebuildRSClaimValue), "sanity check"); 1461 reset_heap_region_claim_values(); 1462 } else { 1463 RebuildRSOutOfRegionClosure rebuild_rs(this); 1464 heap_region_iterate(&rebuild_rs); 1465 } 1466 1467 // Rebuild the strong code root lists for each region 1468 rebuild_strong_code_roots(); 1469 1470 if (true) { // FIXME 1471 MetaspaceGC::compute_new_size(); 1472 } 1473 1474 #ifdef TRACESPINNING 1475 ParallelTaskTerminator::print_termination_counts(); 1476 #endif 1477 1478 // Discard all rset updates 1479 JavaThread::dirty_card_queue_set().abandon_logs(); 1480 assert(!G1DeferredRSUpdate 1481 || (G1DeferredRSUpdate && 1482 (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any"); 1483 1484 _young_list->reset_sampled_info(); 1485 // At this point there should be no regions in the 1486 // entire heap tagged as young. 1487 assert(check_young_list_empty(true /* check_heap */), 1488 "young list should be empty at this point"); 1489 1490 // Update the number of full collections that have been completed. 1491 increment_old_marking_cycles_completed(false /* concurrent */); 1492 1493 _hrs.verify_optional(); 1494 verify_region_sets_optional(); 1495 1496 verify_after_gc(); 1497 1498 // Clear the previous marking bitmap, if needed for bitmap verification. 1499 // Note we cannot do this when we clear the next marking bitmap in 1500 // ConcurrentMark::abort() above since VerifyDuringGC verifies the 1501 // objects marked during a full GC against the previous bitmap. 1502 // But we need to clear it before calling check_bitmaps below since 1503 // the full GC has compacted objects and updated TAMS but not updated 1504 // the prev bitmap. 1505 if (G1VerifyBitmaps) { 1506 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll(); 1507 } 1508 check_bitmaps("Full GC End"); 1509 1510 // Start a new incremental collection set for the next pause 1511 assert(g1_policy()->collection_set() == NULL, "must be"); 1512 g1_policy()->start_incremental_cset_building(); 1513 1514 clear_cset_fast_test(); 1515 1516 init_mutator_alloc_region(); 1517 1518 double end = os::elapsedTime(); 1519 g1_policy()->record_full_collection_end(); 1520 1521 if (G1Log::fine()) { 1522 g1_policy()->print_heap_transition(); 1523 } 1524 1525 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 1526 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 1527 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 1528 // before any GC notifications are raised. 1529 g1mm()->update_sizes(); 1530 1531 gc_epilogue(true); 1532 } 1533 1534 if (G1Log::finer()) { 1535 g1_policy()->print_detailed_heap_transition(true /* full */); 1536 } 1537 1538 print_heap_after_gc(); 1539 trace_heap_after_gc(gc_tracer); 1540 1541 post_full_gc_dump(gc_timer); 1542 1543 gc_timer->register_gc_end(); 1544 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions()); 1545 } 1546 1547 return true; 1548 } 1549 1550 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) { 1551 // do_collection() will return whether it succeeded in performing 1552 // the GC. Currently, there is no facility on the 1553 // do_full_collection() API to notify the caller than the collection 1554 // did not succeed (e.g., because it was locked out by the GC 1555 // locker). So, right now, we'll ignore the return value. 1556 bool dummy = do_collection(true, /* explicit_gc */ 1557 clear_all_soft_refs, 1558 0 /* word_size */); 1559 } 1560 1561 // This code is mostly copied from TenuredGeneration. 1562 void 1563 G1CollectedHeap:: 1564 resize_if_necessary_after_full_collection(size_t word_size) { 1565 // Include the current allocation, if any, and bytes that will be 1566 // pre-allocated to support collections, as "used". 1567 const size_t used_after_gc = used(); 1568 const size_t capacity_after_gc = capacity(); 1569 const size_t free_after_gc = capacity_after_gc - used_after_gc; 1570 1571 // This is enforced in arguments.cpp. 1572 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, 1573 "otherwise the code below doesn't make sense"); 1574 1575 // We don't have floating point command-line arguments 1576 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0; 1577 const double maximum_used_percentage = 1.0 - minimum_free_percentage; 1578 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0; 1579 const double minimum_used_percentage = 1.0 - maximum_free_percentage; 1580 1581 const size_t min_heap_size = collector_policy()->min_heap_byte_size(); 1582 const size_t max_heap_size = collector_policy()->max_heap_byte_size(); 1583 1584 // We have to be careful here as these two calculations can overflow 1585 // 32-bit size_t's. 1586 double used_after_gc_d = (double) used_after_gc; 1587 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage; 1588 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage; 1589 1590 // Let's make sure that they are both under the max heap size, which 1591 // by default will make them fit into a size_t. 1592 double desired_capacity_upper_bound = (double) max_heap_size; 1593 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d, 1594 desired_capacity_upper_bound); 1595 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d, 1596 desired_capacity_upper_bound); 1597 1598 // We can now safely turn them into size_t's. 1599 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d; 1600 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d; 1601 1602 // This assert only makes sense here, before we adjust them 1603 // with respect to the min and max heap size. 1604 assert(minimum_desired_capacity <= maximum_desired_capacity, 1605 err_msg("minimum_desired_capacity = "SIZE_FORMAT", " 1606 "maximum_desired_capacity = "SIZE_FORMAT, 1607 minimum_desired_capacity, maximum_desired_capacity)); 1608 1609 // Should not be greater than the heap max size. No need to adjust 1610 // it with respect to the heap min size as it's a lower bound (i.e., 1611 // we'll try to make the capacity larger than it, not smaller). 1612 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size); 1613 // Should not be less than the heap min size. No need to adjust it 1614 // with respect to the heap max size as it's an upper bound (i.e., 1615 // we'll try to make the capacity smaller than it, not greater). 1616 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size); 1617 1618 if (capacity_after_gc < minimum_desired_capacity) { 1619 // Don't expand unless it's significant 1620 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc; 1621 ergo_verbose4(ErgoHeapSizing, 1622 "attempt heap expansion", 1623 ergo_format_reason("capacity lower than " 1624 "min desired capacity after Full GC") 1625 ergo_format_byte("capacity") 1626 ergo_format_byte("occupancy") 1627 ergo_format_byte_perc("min desired capacity"), 1628 capacity_after_gc, used_after_gc, 1629 minimum_desired_capacity, (double) MinHeapFreeRatio); 1630 expand(expand_bytes); 1631 1632 // No expansion, now see if we want to shrink 1633 } else if (capacity_after_gc > maximum_desired_capacity) { 1634 // Capacity too large, compute shrinking size 1635 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity; 1636 ergo_verbose4(ErgoHeapSizing, 1637 "attempt heap shrinking", 1638 ergo_format_reason("capacity higher than " 1639 "max desired capacity after Full GC") 1640 ergo_format_byte("capacity") 1641 ergo_format_byte("occupancy") 1642 ergo_format_byte_perc("max desired capacity"), 1643 capacity_after_gc, used_after_gc, 1644 maximum_desired_capacity, (double) MaxHeapFreeRatio); 1645 shrink(shrink_bytes); 1646 } 1647 } 1648 1649 1650 HeapWord* 1651 G1CollectedHeap::satisfy_failed_allocation(size_t word_size, 1652 bool* succeeded) { 1653 assert_at_safepoint(true /* should_be_vm_thread */); 1654 1655 *succeeded = true; 1656 // Let's attempt the allocation first. 1657 HeapWord* result = 1658 attempt_allocation_at_safepoint(word_size, 1659 false /* expect_null_mutator_alloc_region */); 1660 if (result != NULL) { 1661 assert(*succeeded, "sanity"); 1662 return result; 1663 } 1664 1665 // In a G1 heap, we're supposed to keep allocation from failing by 1666 // incremental pauses. Therefore, at least for now, we'll favor 1667 // expansion over collection. (This might change in the future if we can 1668 // do something smarter than full collection to satisfy a failed alloc.) 1669 result = expand_and_allocate(word_size); 1670 if (result != NULL) { 1671 assert(*succeeded, "sanity"); 1672 return result; 1673 } 1674 1675 // Expansion didn't work, we'll try to do a Full GC. 1676 bool gc_succeeded = do_collection(false, /* explicit_gc */ 1677 false, /* clear_all_soft_refs */ 1678 word_size); 1679 if (!gc_succeeded) { 1680 *succeeded = false; 1681 return NULL; 1682 } 1683 1684 // Retry the allocation 1685 result = attempt_allocation_at_safepoint(word_size, 1686 true /* expect_null_mutator_alloc_region */); 1687 if (result != NULL) { 1688 assert(*succeeded, "sanity"); 1689 return result; 1690 } 1691 1692 // Then, try a Full GC that will collect all soft references. 1693 gc_succeeded = do_collection(false, /* explicit_gc */ 1694 true, /* clear_all_soft_refs */ 1695 word_size); 1696 if (!gc_succeeded) { 1697 *succeeded = false; 1698 return NULL; 1699 } 1700 1701 // Retry the allocation once more 1702 result = attempt_allocation_at_safepoint(word_size, 1703 true /* expect_null_mutator_alloc_region */); 1704 if (result != NULL) { 1705 assert(*succeeded, "sanity"); 1706 return result; 1707 } 1708 1709 assert(!collector_policy()->should_clear_all_soft_refs(), 1710 "Flag should have been handled and cleared prior to this point"); 1711 1712 // What else? We might try synchronous finalization later. If the total 1713 // space available is large enough for the allocation, then a more 1714 // complete compaction phase than we've tried so far might be 1715 // appropriate. 1716 assert(*succeeded, "sanity"); 1717 return NULL; 1718 } 1719 1720 // Attempting to expand the heap sufficiently 1721 // to support an allocation of the given "word_size". If 1722 // successful, perform the allocation and return the address of the 1723 // allocated block, or else "NULL". 1724 1725 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) { 1726 assert_at_safepoint(true /* should_be_vm_thread */); 1727 1728 verify_region_sets_optional(); 1729 1730 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes); 1731 ergo_verbose1(ErgoHeapSizing, 1732 "attempt heap expansion", 1733 ergo_format_reason("allocation request failed") 1734 ergo_format_byte("allocation request"), 1735 word_size * HeapWordSize); 1736 if (expand(expand_bytes)) { 1737 _hrs.verify_optional(); 1738 verify_region_sets_optional(); 1739 return attempt_allocation_at_safepoint(word_size, 1740 false /* expect_null_mutator_alloc_region */); 1741 } 1742 return NULL; 1743 } 1744 1745 bool G1CollectedHeap::expand(size_t expand_bytes) { 1746 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); 1747 aligned_expand_bytes = align_size_up(aligned_expand_bytes, 1748 HeapRegion::GrainBytes); 1749 ergo_verbose2(ErgoHeapSizing, 1750 "expand the heap", 1751 ergo_format_byte("requested expansion amount") 1752 ergo_format_byte("attempted expansion amount"), 1753 expand_bytes, aligned_expand_bytes); 1754 1755 if (is_maximal_no_gc()) { 1756 ergo_verbose0(ErgoHeapSizing, 1757 "did not expand the heap", 1758 ergo_format_reason("heap already fully expanded")); 1759 return false; 1760 } 1761 1762 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes); 1763 assert(regions_to_expand > 0, "Must expand by at least one region"); 1764 1765 uint expanded_by = _hrs.expand_by(regions_to_expand); 1766 1767 if (expanded_by > 0) { 1768 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes; 1769 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition"); 1770 g1_policy()->record_new_heap_size(num_regions()); 1771 } else { 1772 ergo_verbose0(ErgoHeapSizing, 1773 "did not expand the heap", 1774 ergo_format_reason("heap expansion operation failed")); 1775 // The expansion of the virtual storage space was unsuccessful. 1776 // Let's see if it was because we ran out of swap. 1777 if (G1ExitOnExpansionFailure && 1778 _hrs.available() >= regions_to_expand) { 1779 // We had head room... 1780 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion"); 1781 } 1782 } 1783 return regions_to_expand > 0; 1784 } 1785 1786 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) { 1787 size_t aligned_shrink_bytes = 1788 ReservedSpace::page_align_size_down(shrink_bytes); 1789 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes, 1790 HeapRegion::GrainBytes); 1791 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes); 1792 1793 uint num_regions_removed = _hrs.shrink_by(num_regions_to_remove); 1794 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes; 1795 1796 ergo_verbose3(ErgoHeapSizing, 1797 "shrink the heap", 1798 ergo_format_byte("requested shrinking amount") 1799 ergo_format_byte("aligned shrinking amount") 1800 ergo_format_byte("attempted shrinking amount"), 1801 shrink_bytes, aligned_shrink_bytes, shrunk_bytes); 1802 if (num_regions_removed > 0) { 1803 g1_policy()->record_new_heap_size(num_regions()); 1804 } else { 1805 ergo_verbose0(ErgoHeapSizing, 1806 "did not shrink the heap", 1807 ergo_format_reason("heap shrinking operation failed")); 1808 } 1809 } 1810 1811 void G1CollectedHeap::shrink(size_t shrink_bytes) { 1812 verify_region_sets_optional(); 1813 1814 // We should only reach here at the end of a Full GC which means we 1815 // should not not be holding to any GC alloc regions. The method 1816 // below will make sure of that and do any remaining clean up. 1817 abandon_gc_alloc_regions(); 1818 1819 // Instead of tearing down / rebuilding the free lists here, we 1820 // could instead use the remove_all_pending() method on free_list to 1821 // remove only the ones that we need to remove. 1822 tear_down_region_sets(true /* free_list_only */); 1823 shrink_helper(shrink_bytes); 1824 rebuild_region_sets(true /* free_list_only */); 1825 1826 _hrs.verify_optional(); 1827 verify_region_sets_optional(); 1828 } 1829 1830 // Public methods. 1831 1832 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away 1833 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list 1834 #endif // _MSC_VER 1835 1836 1837 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) : 1838 SharedHeap(policy_), 1839 _g1_policy(policy_), 1840 _dirty_card_queue_set(false), 1841 _into_cset_dirty_card_queue_set(false), 1842 _is_alive_closure_cm(this), 1843 _is_alive_closure_stw(this), 1844 _ref_processor_cm(NULL), 1845 _ref_processor_stw(NULL), 1846 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)), 1847 _bot_shared(NULL), 1848 _evac_failure_scan_stack(NULL), 1849 _mark_in_progress(false), 1850 _cg1r(NULL), _summary_bytes_used(0), 1851 _g1mm(NULL), 1852 _refine_cte_cl(NULL), 1853 _full_collection(false), 1854 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()), 1855 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()), 1856 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()), 1857 _humongous_is_live(), 1858 _has_humongous_reclaim_candidates(false), 1859 _free_regions_coming(false), 1860 _young_list(new YoungList(this)), 1861 _gc_time_stamp(0), 1862 _retained_old_gc_alloc_region(NULL), 1863 _survivor_plab_stats(YoungPLABSize, PLABWeight), 1864 _old_plab_stats(OldPLABSize, PLABWeight), 1865 _expand_heap_after_alloc_failure(true), 1866 _surviving_young_words(NULL), 1867 _old_marking_cycles_started(0), 1868 _old_marking_cycles_completed(0), 1869 _concurrent_cycle_started(false), 1870 _in_cset_fast_test(), 1871 _dirty_cards_region_list(NULL), 1872 _worker_cset_start_region(NULL), 1873 _worker_cset_start_region_time_stamp(NULL), 1874 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()), 1875 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()), 1876 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()), 1877 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) { 1878 1879 _g1h = this; 1880 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) { 1881 vm_exit_during_initialization("Failed necessary allocation."); 1882 } 1883 1884 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2; 1885 1886 int n_queues = MAX2((int)ParallelGCThreads, 1); 1887 _task_queues = new RefToScanQueueSet(n_queues); 1888 1889 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets(); 1890 assert(n_rem_sets > 0, "Invariant."); 1891 1892 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC); 1893 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(unsigned int, n_queues, mtGC); 1894 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC); 1895 1896 for (int i = 0; i < n_queues; i++) { 1897 RefToScanQueue* q = new RefToScanQueue(); 1898 q->initialize(); 1899 _task_queues->register_queue(i, q); 1900 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo(); 1901 } 1902 clear_cset_start_regions(); 1903 1904 // Initialize the G1EvacuationFailureALot counters and flags. 1905 NOT_PRODUCT(reset_evacuation_should_fail();) 1906 1907 guarantee(_task_queues != NULL, "task_queues allocation failure."); 1908 } 1909 1910 jint G1CollectedHeap::initialize() { 1911 CollectedHeap::pre_initialize(); 1912 os::enable_vtime(); 1913 1914 G1Log::init(); 1915 1916 // Necessary to satisfy locking discipline assertions. 1917 1918 MutexLocker x(Heap_lock); 1919 1920 // We have to initialize the printer before committing the heap, as 1921 // it will be used then. 1922 _hr_printer.set_active(G1PrintHeapRegions); 1923 1924 // While there are no constraints in the GC code that HeapWordSize 1925 // be any particular value, there are multiple other areas in the 1926 // system which believe this to be true (e.g. oop->object_size in some 1927 // cases incorrectly returns the size in wordSize units rather than 1928 // HeapWordSize). 1929 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 1930 1931 size_t init_byte_size = collector_policy()->initial_heap_byte_size(); 1932 size_t max_byte_size = collector_policy()->max_heap_byte_size(); 1933 size_t heap_alignment = collector_policy()->heap_alignment(); 1934 1935 // Ensure that the sizes are properly aligned. 1936 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1937 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1938 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap"); 1939 1940 _refine_cte_cl = new RefineCardTableEntryClosure(); 1941 1942 _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl); 1943 1944 // Reserve the maximum. 1945 1946 // When compressed oops are enabled, the preferred heap base 1947 // is calculated by subtracting the requested size from the 1948 // 32Gb boundary and using the result as the base address for 1949 // heap reservation. If the requested size is not aligned to 1950 // HeapRegion::GrainBytes (i.e. the alignment that is passed 1951 // into the ReservedHeapSpace constructor) then the actual 1952 // base of the reserved heap may end up differing from the 1953 // address that was requested (i.e. the preferred heap base). 1954 // If this happens then we could end up using a non-optimal 1955 // compressed oops mode. 1956 1957 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size, 1958 heap_alignment); 1959 1960 // It is important to do this in a way such that concurrent readers can't 1961 // temporarily think something is in the heap. (I've actually seen this 1962 // happen in asserts: DLD.) 1963 _reserved.set_word_size(0); 1964 _reserved.set_start((HeapWord*)heap_rs.base()); 1965 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size())); 1966 1967 // Create the gen rem set (and barrier set) for the entire reserved region. 1968 _rem_set = collector_policy()->create_rem_set(_reserved, 2); 1969 set_barrier_set(rem_set()->bs()); 1970 if (!barrier_set()->is_a(BarrierSet::G1SATBCTLogging)) { 1971 vm_exit_during_initialization("G1 requires a G1SATBLoggingCardTableModRefBS"); 1972 return JNI_ENOMEM; 1973 } 1974 1975 // Also create a G1 rem set. 1976 _g1_rem_set = new G1RemSet(this, g1_barrier_set()); 1977 1978 // Carve out the G1 part of the heap. 1979 1980 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size); 1981 G1RegionToSpaceMapper* heap_storage = 1982 G1RegionToSpaceMapper::create_mapper(g1_rs, 1983 UseLargePages ? os::large_page_size() : os::vm_page_size(), 1984 HeapRegion::GrainBytes, 1985 1, 1986 mtJavaHeap); 1987 heap_storage->set_mapping_changed_listener(&_listener); 1988 1989 // Reserve space for the block offset table. We do not support automatic uncommit 1990 // for the card table at this time. BOT only. 1991 ReservedSpace bot_rs(G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize)); 1992 G1RegionToSpaceMapper* bot_storage = 1993 G1RegionToSpaceMapper::create_mapper(bot_rs, 1994 os::vm_page_size(), 1995 HeapRegion::GrainBytes, 1996 G1BlockOffsetSharedArray::N_bytes, 1997 mtGC); 1998 1999 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize)); 2000 G1RegionToSpaceMapper* cardtable_storage = 2001 G1RegionToSpaceMapper::create_mapper(cardtable_rs, 2002 os::vm_page_size(), 2003 HeapRegion::GrainBytes, 2004 G1BlockOffsetSharedArray::N_bytes, 2005 mtGC); 2006 2007 // Reserve space for the card counts table. 2008 ReservedSpace card_counts_rs(G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize)); 2009 G1RegionToSpaceMapper* card_counts_storage = 2010 G1RegionToSpaceMapper::create_mapper(card_counts_rs, 2011 os::vm_page_size(), 2012 HeapRegion::GrainBytes, 2013 G1BlockOffsetSharedArray::N_bytes, 2014 mtGC); 2015 2016 // Reserve space for prev and next bitmap. 2017 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size()); 2018 2019 ReservedSpace prev_bitmap_rs(ReservedSpace::allocation_align_size_up(bitmap_size)); 2020 G1RegionToSpaceMapper* prev_bitmap_storage = 2021 G1RegionToSpaceMapper::create_mapper(prev_bitmap_rs, 2022 os::vm_page_size(), 2023 HeapRegion::GrainBytes, 2024 CMBitMap::mark_distance(), 2025 mtGC); 2026 2027 ReservedSpace next_bitmap_rs(ReservedSpace::allocation_align_size_up(bitmap_size)); 2028 G1RegionToSpaceMapper* next_bitmap_storage = 2029 G1RegionToSpaceMapper::create_mapper(next_bitmap_rs, 2030 os::vm_page_size(), 2031 HeapRegion::GrainBytes, 2032 CMBitMap::mark_distance(), 2033 mtGC); 2034 2035 _hrs.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage); 2036 g1_barrier_set()->initialize(cardtable_storage); 2037 // Do later initialization work for concurrent refinement. 2038 _cg1r->init(card_counts_storage); 2039 2040 // 6843694 - ensure that the maximum region index can fit 2041 // in the remembered set structures. 2042 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; 2043 guarantee((max_regions() - 1) <= max_region_idx, "too many regions"); 2044 2045 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; 2046 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); 2047 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region, 2048 "too many cards per region"); 2049 2050 FreeRegionList::set_unrealistically_long_length(max_regions() + 1); 2051 2052 _bot_shared = new G1BlockOffsetSharedArray(_reserved, bot_storage); 2053 2054 _g1h = this; 2055 2056 _in_cset_fast_test.initialize(_hrs.reserved().start(), _hrs.reserved().end(), HeapRegion::GrainBytes); 2057 _humongous_is_live.initialize(_hrs.reserved().start(), _hrs.reserved().end(), HeapRegion::GrainBytes); 2058 2059 // Create the ConcurrentMark data structure and thread. 2060 // (Must do this late, so that "max_regions" is defined.) 2061 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage); 2062 if (_cm == NULL || !_cm->completed_initialization()) { 2063 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark"); 2064 return JNI_ENOMEM; 2065 } 2066 _cmThread = _cm->cmThread(); 2067 2068 // Initialize the from_card cache structure of HeapRegionRemSet. 2069 HeapRegionRemSet::init_heap(max_regions()); 2070 2071 // Now expand into the initial heap size. 2072 if (!expand(init_byte_size)) { 2073 vm_shutdown_during_initialization("Failed to allocate initial heap."); 2074 return JNI_ENOMEM; 2075 } 2076 2077 // Perform any initialization actions delegated to the policy. 2078 g1_policy()->init(); 2079 2080 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon, 2081 SATB_Q_FL_lock, 2082 G1SATBProcessCompletedThreshold, 2083 Shared_SATB_Q_lock); 2084 2085 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl, 2086 DirtyCardQ_CBL_mon, 2087 DirtyCardQ_FL_lock, 2088 concurrent_g1_refine()->yellow_zone(), 2089 concurrent_g1_refine()->red_zone(), 2090 Shared_DirtyCardQ_lock); 2091 2092 if (G1DeferredRSUpdate) { 2093 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code 2094 DirtyCardQ_CBL_mon, 2095 DirtyCardQ_FL_lock, 2096 -1, // never trigger processing 2097 -1, // no limit on length 2098 Shared_DirtyCardQ_lock, 2099 &JavaThread::dirty_card_queue_set()); 2100 } 2101 2102 // Initialize the card queue set used to hold cards containing 2103 // references into the collection set. 2104 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code 2105 DirtyCardQ_CBL_mon, 2106 DirtyCardQ_FL_lock, 2107 -1, // never trigger processing 2108 -1, // no limit on length 2109 Shared_DirtyCardQ_lock, 2110 &JavaThread::dirty_card_queue_set()); 2111 2112 // In case we're keeping closure specialization stats, initialize those 2113 // counts and that mechanism. 2114 SpecializationStats::clear(); 2115 2116 // Here we allocate the dummy HeapRegion that is required by the 2117 // G1AllocRegion class. 2118 HeapRegion* dummy_region = _hrs.get_dummy_region(); 2119 2120 // We'll re-use the same region whether the alloc region will 2121 // require BOT updates or not and, if it doesn't, then a non-young 2122 // region will complain that it cannot support allocations without 2123 // BOT updates. So we'll tag the dummy region as young to avoid that. 2124 dummy_region->set_young(); 2125 // Make sure it's full. 2126 dummy_region->set_top(dummy_region->end()); 2127 G1AllocRegion::setup(this, dummy_region); 2128 2129 init_mutator_alloc_region(); 2130 2131 // Do create of the monitoring and management support so that 2132 // values in the heap have been properly initialized. 2133 _g1mm = new G1MonitoringSupport(this); 2134 2135 G1StringDedup::initialize(); 2136 2137 return JNI_OK; 2138 } 2139 2140 void G1CollectedHeap::stop() { 2141 // Stop all concurrent threads. We do this to make sure these threads 2142 // do not continue to execute and access resources (e.g. gclog_or_tty) 2143 // that are destroyed during shutdown. 2144 _cg1r->stop(); 2145 _cmThread->stop(); 2146 if (G1StringDedup::is_enabled()) { 2147 G1StringDedup::stop(); 2148 } 2149 } 2150 2151 void G1CollectedHeap::clear_humongous_is_live_table() { 2152 guarantee(G1ReclaimDeadHumongousObjectsAtYoungGC, "Should only be called if true"); 2153 _humongous_is_live.clear(); 2154 } 2155 2156 size_t G1CollectedHeap::conservative_max_heap_alignment() { 2157 return HeapRegion::max_region_size(); 2158 } 2159 2160 void G1CollectedHeap::ref_processing_init() { 2161 // Reference processing in G1 currently works as follows: 2162 // 2163 // * There are two reference processor instances. One is 2164 // used to record and process discovered references 2165 // during concurrent marking; the other is used to 2166 // record and process references during STW pauses 2167 // (both full and incremental). 2168 // * Both ref processors need to 'span' the entire heap as 2169 // the regions in the collection set may be dotted around. 2170 // 2171 // * For the concurrent marking ref processor: 2172 // * Reference discovery is enabled at initial marking. 2173 // * Reference discovery is disabled and the discovered 2174 // references processed etc during remarking. 2175 // * Reference discovery is MT (see below). 2176 // * Reference discovery requires a barrier (see below). 2177 // * Reference processing may or may not be MT 2178 // (depending on the value of ParallelRefProcEnabled 2179 // and ParallelGCThreads). 2180 // * A full GC disables reference discovery by the CM 2181 // ref processor and abandons any entries on it's 2182 // discovered lists. 2183 // 2184 // * For the STW processor: 2185 // * Non MT discovery is enabled at the start of a full GC. 2186 // * Processing and enqueueing during a full GC is non-MT. 2187 // * During a full GC, references are processed after marking. 2188 // 2189 // * Discovery (may or may not be MT) is enabled at the start 2190 // of an incremental evacuation pause. 2191 // * References are processed near the end of a STW evacuation pause. 2192 // * For both types of GC: 2193 // * Discovery is atomic - i.e. not concurrent. 2194 // * Reference discovery will not need a barrier. 2195 2196 SharedHeap::ref_processing_init(); 2197 MemRegion mr = reserved_region(); 2198 2199 // Concurrent Mark ref processor 2200 _ref_processor_cm = 2201 new ReferenceProcessor(mr, // span 2202 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2203 // mt processing 2204 (int) ParallelGCThreads, 2205 // degree of mt processing 2206 (ParallelGCThreads > 1) || (ConcGCThreads > 1), 2207 // mt discovery 2208 (int) MAX2(ParallelGCThreads, ConcGCThreads), 2209 // degree of mt discovery 2210 false, 2211 // Reference discovery is not atomic 2212 &_is_alive_closure_cm); 2213 // is alive closure 2214 // (for efficiency/performance) 2215 2216 // STW ref processor 2217 _ref_processor_stw = 2218 new ReferenceProcessor(mr, // span 2219 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2220 // mt processing 2221 MAX2((int)ParallelGCThreads, 1), 2222 // degree of mt processing 2223 (ParallelGCThreads > 1), 2224 // mt discovery 2225 MAX2((int)ParallelGCThreads, 1), 2226 // degree of mt discovery 2227 true, 2228 // Reference discovery is atomic 2229 &_is_alive_closure_stw); 2230 // is alive closure 2231 // (for efficiency/performance) 2232 } 2233 2234 size_t G1CollectedHeap::capacity() const { 2235 return _hrs.length() * HeapRegion::GrainBytes; 2236 } 2237 2238 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) { 2239 assert(!hr->continuesHumongous(), "pre-condition"); 2240 hr->reset_gc_time_stamp(); 2241 if (hr->startsHumongous()) { 2242 uint first_index = hr->hrs_index() + 1; 2243 uint last_index = hr->last_hc_index(); 2244 for (uint i = first_index; i < last_index; i += 1) { 2245 HeapRegion* chr = region_at(i); 2246 assert(chr->continuesHumongous(), "sanity"); 2247 chr->reset_gc_time_stamp(); 2248 } 2249 } 2250 } 2251 2252 #ifndef PRODUCT 2253 class CheckGCTimeStampsHRClosure : public HeapRegionClosure { 2254 private: 2255 unsigned _gc_time_stamp; 2256 bool _failures; 2257 2258 public: 2259 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) : 2260 _gc_time_stamp(gc_time_stamp), _failures(false) { } 2261 2262 virtual bool doHeapRegion(HeapRegion* hr) { 2263 unsigned region_gc_time_stamp = hr->get_gc_time_stamp(); 2264 if (_gc_time_stamp != region_gc_time_stamp) { 2265 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, " 2266 "expected %d", HR_FORMAT_PARAMS(hr), 2267 region_gc_time_stamp, _gc_time_stamp); 2268 _failures = true; 2269 } 2270 return false; 2271 } 2272 2273 bool failures() { return _failures; } 2274 }; 2275 2276 void G1CollectedHeap::check_gc_time_stamps() { 2277 CheckGCTimeStampsHRClosure cl(_gc_time_stamp); 2278 heap_region_iterate(&cl); 2279 guarantee(!cl.failures(), "all GC time stamps should have been reset"); 2280 } 2281 #endif // PRODUCT 2282 2283 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, 2284 DirtyCardQueue* into_cset_dcq, 2285 bool concurrent, 2286 uint worker_i) { 2287 // Clean cards in the hot card cache 2288 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 2289 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq); 2290 2291 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 2292 int n_completed_buffers = 0; 2293 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) { 2294 n_completed_buffers++; 2295 } 2296 g1_policy()->phase_times()->record_update_rs_processed_buffers(worker_i, n_completed_buffers); 2297 dcqs.clear_n_completed_buffers(); 2298 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!"); 2299 } 2300 2301 2302 // Computes the sum of the storage used by the various regions. 2303 2304 size_t G1CollectedHeap::used() const { 2305 assert(Heap_lock->owner() != NULL, 2306 "Should be owned on this thread's behalf."); 2307 size_t result = _summary_bytes_used; 2308 // Read only once in case it is set to NULL concurrently 2309 HeapRegion* hr = _mutator_alloc_region.get(); 2310 if (hr != NULL) 2311 result += hr->used(); 2312 return result; 2313 } 2314 2315 size_t G1CollectedHeap::used_unlocked() const { 2316 size_t result = _summary_bytes_used; 2317 return result; 2318 } 2319 2320 class SumUsedClosure: public HeapRegionClosure { 2321 size_t _used; 2322 public: 2323 SumUsedClosure() : _used(0) {} 2324 bool doHeapRegion(HeapRegion* r) { 2325 if (!r->continuesHumongous()) { 2326 _used += r->used(); 2327 } 2328 return false; 2329 } 2330 size_t result() { return _used; } 2331 }; 2332 2333 size_t G1CollectedHeap::recalculate_used() const { 2334 double recalculate_used_start = os::elapsedTime(); 2335 2336 SumUsedClosure blk; 2337 heap_region_iterate(&blk); 2338 2339 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0); 2340 return blk.result(); 2341 } 2342 2343 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 2344 switch (cause) { 2345 case GCCause::_gc_locker: return GCLockerInvokesConcurrent; 2346 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent; 2347 case GCCause::_g1_humongous_allocation: return true; 2348 default: return false; 2349 } 2350 } 2351 2352 #ifndef PRODUCT 2353 void G1CollectedHeap::allocate_dummy_regions() { 2354 // Let's fill up most of the region 2355 size_t word_size = HeapRegion::GrainWords - 1024; 2356 // And as a result the region we'll allocate will be humongous. 2357 guarantee(isHumongous(word_size), "sanity"); 2358 2359 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) { 2360 // Let's use the existing mechanism for the allocation 2361 HeapWord* dummy_obj = humongous_obj_allocate(word_size); 2362 if (dummy_obj != NULL) { 2363 MemRegion mr(dummy_obj, word_size); 2364 CollectedHeap::fill_with_object(mr); 2365 } else { 2366 // If we can't allocate once, we probably cannot allocate 2367 // again. Let's get out of the loop. 2368 break; 2369 } 2370 } 2371 } 2372 #endif // !PRODUCT 2373 2374 void G1CollectedHeap::increment_old_marking_cycles_started() { 2375 assert(_old_marking_cycles_started == _old_marking_cycles_completed || 2376 _old_marking_cycles_started == _old_marking_cycles_completed + 1, 2377 err_msg("Wrong marking cycle count (started: %d, completed: %d)", 2378 _old_marking_cycles_started, _old_marking_cycles_completed)); 2379 2380 _old_marking_cycles_started++; 2381 } 2382 2383 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) { 2384 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 2385 2386 // We assume that if concurrent == true, then the caller is a 2387 // concurrent thread that was joined the Suspendible Thread 2388 // Set. If there's ever a cheap way to check this, we should add an 2389 // assert here. 2390 2391 // Given that this method is called at the end of a Full GC or of a 2392 // concurrent cycle, and those can be nested (i.e., a Full GC can 2393 // interrupt a concurrent cycle), the number of full collections 2394 // completed should be either one (in the case where there was no 2395 // nesting) or two (when a Full GC interrupted a concurrent cycle) 2396 // behind the number of full collections started. 2397 2398 // This is the case for the inner caller, i.e. a Full GC. 2399 assert(concurrent || 2400 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || 2401 (_old_marking_cycles_started == _old_marking_cycles_completed + 2), 2402 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u " 2403 "is inconsistent with _old_marking_cycles_completed = %u", 2404 _old_marking_cycles_started, _old_marking_cycles_completed)); 2405 2406 // This is the case for the outer caller, i.e. the concurrent cycle. 2407 assert(!concurrent || 2408 (_old_marking_cycles_started == _old_marking_cycles_completed + 1), 2409 err_msg("for outer caller (concurrent cycle): " 2410 "_old_marking_cycles_started = %u " 2411 "is inconsistent with _old_marking_cycles_completed = %u", 2412 _old_marking_cycles_started, _old_marking_cycles_completed)); 2413 2414 _old_marking_cycles_completed += 1; 2415 2416 // We need to clear the "in_progress" flag in the CM thread before 2417 // we wake up any waiters (especially when ExplicitInvokesConcurrent 2418 // is set) so that if a waiter requests another System.gc() it doesn't 2419 // incorrectly see that a marking cycle is still in progress. 2420 if (concurrent) { 2421 _cmThread->clear_in_progress(); 2422 } 2423 2424 // This notify_all() will ensure that a thread that called 2425 // System.gc() with (with ExplicitGCInvokesConcurrent set or not) 2426 // and it's waiting for a full GC to finish will be woken up. It is 2427 // waiting in VM_G1IncCollectionPause::doit_epilogue(). 2428 FullGCCount_lock->notify_all(); 2429 } 2430 2431 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) { 2432 _concurrent_cycle_started = true; 2433 _gc_timer_cm->register_gc_start(start_time); 2434 2435 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start()); 2436 trace_heap_before_gc(_gc_tracer_cm); 2437 } 2438 2439 void G1CollectedHeap::register_concurrent_cycle_end() { 2440 if (_concurrent_cycle_started) { 2441 if (_cm->has_aborted()) { 2442 _gc_tracer_cm->report_concurrent_mode_failure(); 2443 } 2444 2445 _gc_timer_cm->register_gc_end(); 2446 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions()); 2447 2448 _concurrent_cycle_started = false; 2449 } 2450 } 2451 2452 void G1CollectedHeap::trace_heap_after_concurrent_cycle() { 2453 if (_concurrent_cycle_started) { 2454 trace_heap_after_gc(_gc_tracer_cm); 2455 } 2456 } 2457 2458 G1YCType G1CollectedHeap::yc_type() { 2459 bool is_young = g1_policy()->gcs_are_young(); 2460 bool is_initial_mark = g1_policy()->during_initial_mark_pause(); 2461 bool is_during_mark = mark_in_progress(); 2462 2463 if (is_initial_mark) { 2464 return InitialMark; 2465 } else if (is_during_mark) { 2466 return DuringMark; 2467 } else if (is_young) { 2468 return Normal; 2469 } else { 2470 return Mixed; 2471 } 2472 } 2473 2474 void G1CollectedHeap::collect(GCCause::Cause cause) { 2475 assert_heap_not_locked(); 2476 2477 unsigned int gc_count_before; 2478 unsigned int old_marking_count_before; 2479 bool retry_gc; 2480 2481 do { 2482 retry_gc = false; 2483 2484 { 2485 MutexLocker ml(Heap_lock); 2486 2487 // Read the GC count while holding the Heap_lock 2488 gc_count_before = total_collections(); 2489 old_marking_count_before = _old_marking_cycles_started; 2490 } 2491 2492 if (should_do_concurrent_full_gc(cause)) { 2493 // Schedule an initial-mark evacuation pause that will start a 2494 // concurrent cycle. We're setting word_size to 0 which means that 2495 // we are not requesting a post-GC allocation. 2496 VM_G1IncCollectionPause op(gc_count_before, 2497 0, /* word_size */ 2498 true, /* should_initiate_conc_mark */ 2499 g1_policy()->max_pause_time_ms(), 2500 cause); 2501 2502 VMThread::execute(&op); 2503 if (!op.pause_succeeded()) { 2504 if (old_marking_count_before == _old_marking_cycles_started) { 2505 retry_gc = op.should_retry_gc(); 2506 } else { 2507 // A Full GC happened while we were trying to schedule the 2508 // initial-mark GC. No point in starting a new cycle given 2509 // that the whole heap was collected anyway. 2510 } 2511 2512 if (retry_gc) { 2513 if (GC_locker::is_active_and_needs_gc()) { 2514 GC_locker::stall_until_clear(); 2515 } 2516 } 2517 } 2518 } else { 2519 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc 2520 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { 2521 2522 // Schedule a standard evacuation pause. We're setting word_size 2523 // to 0 which means that we are not requesting a post-GC allocation. 2524 VM_G1IncCollectionPause op(gc_count_before, 2525 0, /* word_size */ 2526 false, /* should_initiate_conc_mark */ 2527 g1_policy()->max_pause_time_ms(), 2528 cause); 2529 VMThread::execute(&op); 2530 } else { 2531 // Schedule a Full GC. 2532 VM_G1CollectFull op(gc_count_before, old_marking_count_before, cause); 2533 VMThread::execute(&op); 2534 } 2535 } 2536 } while (retry_gc); 2537 } 2538 2539 bool G1CollectedHeap::is_in(const void* p) const { 2540 if (_hrs.reserved().contains(p)) { 2541 // Given that we know that p is in the reserved space, 2542 // heap_region_containing_raw() should successfully 2543 // return the containing region. 2544 HeapRegion* hr = heap_region_containing_raw(p); 2545 return hr->is_in(p); 2546 } else { 2547 return false; 2548 } 2549 } 2550 2551 #ifdef ASSERT 2552 bool G1CollectedHeap::is_in_exact(const void* p) const { 2553 bool contains = reserved_region().contains(p); 2554 bool available = _hrs.is_available(addr_to_region((HeapWord*)p)); 2555 if (contains && available) { 2556 return true; 2557 } else { 2558 return false; 2559 } 2560 } 2561 #endif 2562 2563 // Iteration functions. 2564 2565 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion. 2566 2567 class IterateOopClosureRegionClosure: public HeapRegionClosure { 2568 ExtendedOopClosure* _cl; 2569 public: 2570 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {} 2571 bool doHeapRegion(HeapRegion* r) { 2572 if (!r->continuesHumongous()) { 2573 r->oop_iterate(_cl); 2574 } 2575 return false; 2576 } 2577 }; 2578 2579 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) { 2580 IterateOopClosureRegionClosure blk(cl); 2581 heap_region_iterate(&blk); 2582 } 2583 2584 // Iterates an ObjectClosure over all objects within a HeapRegion. 2585 2586 class IterateObjectClosureRegionClosure: public HeapRegionClosure { 2587 ObjectClosure* _cl; 2588 public: 2589 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} 2590 bool doHeapRegion(HeapRegion* r) { 2591 if (! r->continuesHumongous()) { 2592 r->object_iterate(_cl); 2593 } 2594 return false; 2595 } 2596 }; 2597 2598 void G1CollectedHeap::object_iterate(ObjectClosure* cl) { 2599 IterateObjectClosureRegionClosure blk(cl); 2600 heap_region_iterate(&blk); 2601 } 2602 2603 // Calls a SpaceClosure on a HeapRegion. 2604 2605 class SpaceClosureRegionClosure: public HeapRegionClosure { 2606 SpaceClosure* _cl; 2607 public: 2608 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {} 2609 bool doHeapRegion(HeapRegion* r) { 2610 _cl->do_space(r); 2611 return false; 2612 } 2613 }; 2614 2615 void G1CollectedHeap::space_iterate(SpaceClosure* cl) { 2616 SpaceClosureRegionClosure blk(cl); 2617 heap_region_iterate(&blk); 2618 } 2619 2620 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { 2621 _hrs.iterate(cl); 2622 } 2623 2624 void 2625 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl, 2626 uint worker_id, 2627 uint num_workers, 2628 jint claim_value) const { 2629 _hrs.par_iterate(cl, worker_id, num_workers, claim_value); 2630 } 2631 2632 class ResetClaimValuesClosure: public HeapRegionClosure { 2633 public: 2634 bool doHeapRegion(HeapRegion* r) { 2635 r->set_claim_value(HeapRegion::InitialClaimValue); 2636 return false; 2637 } 2638 }; 2639 2640 void G1CollectedHeap::reset_heap_region_claim_values() { 2641 ResetClaimValuesClosure blk; 2642 heap_region_iterate(&blk); 2643 } 2644 2645 void G1CollectedHeap::reset_cset_heap_region_claim_values() { 2646 ResetClaimValuesClosure blk; 2647 collection_set_iterate(&blk); 2648 } 2649 2650 #ifdef ASSERT 2651 // This checks whether all regions in the heap have the correct claim 2652 // value. I also piggy-backed on this a check to ensure that the 2653 // humongous_start_region() information on "continues humongous" 2654 // regions is correct. 2655 2656 class CheckClaimValuesClosure : public HeapRegionClosure { 2657 private: 2658 jint _claim_value; 2659 uint _failures; 2660 HeapRegion* _sh_region; 2661 2662 public: 2663 CheckClaimValuesClosure(jint claim_value) : 2664 _claim_value(claim_value), _failures(0), _sh_region(NULL) { } 2665 bool doHeapRegion(HeapRegion* r) { 2666 if (r->claim_value() != _claim_value) { 2667 gclog_or_tty->print_cr("Region " HR_FORMAT ", " 2668 "claim value = %d, should be %d", 2669 HR_FORMAT_PARAMS(r), 2670 r->claim_value(), _claim_value); 2671 ++_failures; 2672 } 2673 if (!r->isHumongous()) { 2674 _sh_region = NULL; 2675 } else if (r->startsHumongous()) { 2676 _sh_region = r; 2677 } else if (r->continuesHumongous()) { 2678 if (r->humongous_start_region() != _sh_region) { 2679 gclog_or_tty->print_cr("Region " HR_FORMAT ", " 2680 "HS = "PTR_FORMAT", should be "PTR_FORMAT, 2681 HR_FORMAT_PARAMS(r), 2682 r->humongous_start_region(), 2683 _sh_region); 2684 ++_failures; 2685 } 2686 } 2687 return false; 2688 } 2689 uint failures() { return _failures; } 2690 }; 2691 2692 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) { 2693 CheckClaimValuesClosure cl(claim_value); 2694 heap_region_iterate(&cl); 2695 return cl.failures() == 0; 2696 } 2697 2698 class CheckClaimValuesInCSetHRClosure: public HeapRegionClosure { 2699 private: 2700 jint _claim_value; 2701 uint _failures; 2702 2703 public: 2704 CheckClaimValuesInCSetHRClosure(jint claim_value) : 2705 _claim_value(claim_value), _failures(0) { } 2706 2707 uint failures() { return _failures; } 2708 2709 bool doHeapRegion(HeapRegion* hr) { 2710 assert(hr->in_collection_set(), "how?"); 2711 assert(!hr->isHumongous(), "H-region in CSet"); 2712 if (hr->claim_value() != _claim_value) { 2713 gclog_or_tty->print_cr("CSet Region " HR_FORMAT ", " 2714 "claim value = %d, should be %d", 2715 HR_FORMAT_PARAMS(hr), 2716 hr->claim_value(), _claim_value); 2717 _failures += 1; 2718 } 2719 return false; 2720 } 2721 }; 2722 2723 bool G1CollectedHeap::check_cset_heap_region_claim_values(jint claim_value) { 2724 CheckClaimValuesInCSetHRClosure cl(claim_value); 2725 collection_set_iterate(&cl); 2726 return cl.failures() == 0; 2727 } 2728 #endif // ASSERT 2729 2730 // Clear the cached CSet starting regions and (more importantly) 2731 // the time stamps. Called when we reset the GC time stamp. 2732 void G1CollectedHeap::clear_cset_start_regions() { 2733 assert(_worker_cset_start_region != NULL, "sanity"); 2734 assert(_worker_cset_start_region_time_stamp != NULL, "sanity"); 2735 2736 int n_queues = MAX2((int)ParallelGCThreads, 1); 2737 for (int i = 0; i < n_queues; i++) { 2738 _worker_cset_start_region[i] = NULL; 2739 _worker_cset_start_region_time_stamp[i] = 0; 2740 } 2741 } 2742 2743 // Given the id of a worker, obtain or calculate a suitable 2744 // starting region for iterating over the current collection set. 2745 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) { 2746 assert(get_gc_time_stamp() > 0, "should have been updated by now"); 2747 2748 HeapRegion* result = NULL; 2749 unsigned gc_time_stamp = get_gc_time_stamp(); 2750 2751 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) { 2752 // Cached starting region for current worker was set 2753 // during the current pause - so it's valid. 2754 // Note: the cached starting heap region may be NULL 2755 // (when the collection set is empty). 2756 result = _worker_cset_start_region[worker_i]; 2757 assert(result == NULL || result->in_collection_set(), "sanity"); 2758 return result; 2759 } 2760 2761 // The cached entry was not valid so let's calculate 2762 // a suitable starting heap region for this worker. 2763 2764 // We want the parallel threads to start their collection 2765 // set iteration at different collection set regions to 2766 // avoid contention. 2767 // If we have: 2768 // n collection set regions 2769 // p threads 2770 // Then thread t will start at region floor ((t * n) / p) 2771 2772 result = g1_policy()->collection_set(); 2773 if (G1CollectedHeap::use_parallel_gc_threads()) { 2774 uint cs_size = g1_policy()->cset_region_length(); 2775 uint active_workers = workers()->active_workers(); 2776 assert(UseDynamicNumberOfGCThreads || 2777 active_workers == workers()->total_workers(), 2778 "Unless dynamic should use total workers"); 2779 2780 uint end_ind = (cs_size * worker_i) / active_workers; 2781 uint start_ind = 0; 2782 2783 if (worker_i > 0 && 2784 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) { 2785 // Previous workers starting region is valid 2786 // so let's iterate from there 2787 start_ind = (cs_size * (worker_i - 1)) / active_workers; 2788 result = _worker_cset_start_region[worker_i - 1]; 2789 } 2790 2791 for (uint i = start_ind; i < end_ind; i++) { 2792 result = result->next_in_collection_set(); 2793 } 2794 } 2795 2796 // Note: the calculated starting heap region may be NULL 2797 // (when the collection set is empty). 2798 assert(result == NULL || result->in_collection_set(), "sanity"); 2799 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp, 2800 "should be updated only once per pause"); 2801 _worker_cset_start_region[worker_i] = result; 2802 OrderAccess::storestore(); 2803 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp; 2804 return result; 2805 } 2806 2807 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) { 2808 HeapRegion* r = g1_policy()->collection_set(); 2809 while (r != NULL) { 2810 HeapRegion* next = r->next_in_collection_set(); 2811 if (cl->doHeapRegion(r)) { 2812 cl->incomplete(); 2813 return; 2814 } 2815 r = next; 2816 } 2817 } 2818 2819 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r, 2820 HeapRegionClosure *cl) { 2821 if (r == NULL) { 2822 // The CSet is empty so there's nothing to do. 2823 return; 2824 } 2825 2826 assert(r->in_collection_set(), 2827 "Start region must be a member of the collection set."); 2828 HeapRegion* cur = r; 2829 while (cur != NULL) { 2830 HeapRegion* next = cur->next_in_collection_set(); 2831 if (cl->doHeapRegion(cur) && false) { 2832 cl->incomplete(); 2833 return; 2834 } 2835 cur = next; 2836 } 2837 cur = g1_policy()->collection_set(); 2838 while (cur != r) { 2839 HeapRegion* next = cur->next_in_collection_set(); 2840 if (cl->doHeapRegion(cur) && false) { 2841 cl->incomplete(); 2842 return; 2843 } 2844 cur = next; 2845 } 2846 } 2847 2848 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const { 2849 HeapRegion* result = _hrs.next_region_in_heap(from); 2850 while (result != NULL && result->isHumongous()) { 2851 result = _hrs.next_region_in_heap(result); 2852 } 2853 return result; 2854 } 2855 2856 Space* G1CollectedHeap::space_containing(const void* addr) const { 2857 return heap_region_containing(addr); 2858 } 2859 2860 HeapWord* G1CollectedHeap::block_start(const void* addr) const { 2861 Space* sp = space_containing(addr); 2862 return sp->block_start(addr); 2863 } 2864 2865 size_t G1CollectedHeap::block_size(const HeapWord* addr) const { 2866 Space* sp = space_containing(addr); 2867 return sp->block_size(addr); 2868 } 2869 2870 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { 2871 Space* sp = space_containing(addr); 2872 return sp->block_is_obj(addr); 2873 } 2874 2875 bool G1CollectedHeap::supports_tlab_allocation() const { 2876 return true; 2877 } 2878 2879 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { 2880 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes; 2881 } 2882 2883 size_t G1CollectedHeap::tlab_used(Thread* ignored) const { 2884 return young_list()->eden_used_bytes(); 2885 } 2886 2887 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size 2888 // must be smaller than the humongous object limit. 2889 size_t G1CollectedHeap::max_tlab_size() const { 2890 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment); 2891 } 2892 2893 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { 2894 // Return the remaining space in the cur alloc region, but not less than 2895 // the min TLAB size. 2896 2897 // Also, this value can be at most the humongous object threshold, 2898 // since we can't allow tlabs to grow big enough to accommodate 2899 // humongous objects. 2900 2901 HeapRegion* hr = _mutator_alloc_region.get(); 2902 size_t max_tlab = max_tlab_size() * wordSize; 2903 if (hr == NULL) { 2904 return max_tlab; 2905 } else { 2906 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab); 2907 } 2908 } 2909 2910 size_t G1CollectedHeap::max_capacity() const { 2911 return _hrs.reserved().byte_size(); 2912 } 2913 2914 jlong G1CollectedHeap::millis_since_last_gc() { 2915 // assert(false, "NYI"); 2916 return 0; 2917 } 2918 2919 void G1CollectedHeap::prepare_for_verify() { 2920 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) { 2921 ensure_parsability(false); 2922 } 2923 g1_rem_set()->prepare_for_verify(); 2924 } 2925 2926 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr, 2927 VerifyOption vo) { 2928 switch (vo) { 2929 case VerifyOption_G1UsePrevMarking: 2930 return hr->obj_allocated_since_prev_marking(obj); 2931 case VerifyOption_G1UseNextMarking: 2932 return hr->obj_allocated_since_next_marking(obj); 2933 case VerifyOption_G1UseMarkWord: 2934 return false; 2935 default: 2936 ShouldNotReachHere(); 2937 } 2938 return false; // keep some compilers happy 2939 } 2940 2941 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) { 2942 switch (vo) { 2943 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start(); 2944 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start(); 2945 case VerifyOption_G1UseMarkWord: return NULL; 2946 default: ShouldNotReachHere(); 2947 } 2948 return NULL; // keep some compilers happy 2949 } 2950 2951 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) { 2952 switch (vo) { 2953 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj); 2954 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj); 2955 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked(); 2956 default: ShouldNotReachHere(); 2957 } 2958 return false; // keep some compilers happy 2959 } 2960 2961 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) { 2962 switch (vo) { 2963 case VerifyOption_G1UsePrevMarking: return "PTAMS"; 2964 case VerifyOption_G1UseNextMarking: return "NTAMS"; 2965 case VerifyOption_G1UseMarkWord: return "NONE"; 2966 default: ShouldNotReachHere(); 2967 } 2968 return NULL; // keep some compilers happy 2969 } 2970 2971 class VerifyRootsClosure: public OopClosure { 2972 private: 2973 G1CollectedHeap* _g1h; 2974 VerifyOption _vo; 2975 bool _failures; 2976 public: 2977 // _vo == UsePrevMarking -> use "prev" marking information, 2978 // _vo == UseNextMarking -> use "next" marking information, 2979 // _vo == UseMarkWord -> use mark word from object header. 2980 VerifyRootsClosure(VerifyOption vo) : 2981 _g1h(G1CollectedHeap::heap()), 2982 _vo(vo), 2983 _failures(false) { } 2984 2985 bool failures() { return _failures; } 2986 2987 template <class T> void do_oop_nv(T* p) { 2988 T heap_oop = oopDesc::load_heap_oop(p); 2989 if (!oopDesc::is_null(heap_oop)) { 2990 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 2991 if (_g1h->is_obj_dead_cond(obj, _vo)) { 2992 gclog_or_tty->print_cr("Root location "PTR_FORMAT" " 2993 "points to dead obj "PTR_FORMAT, p, (void*) obj); 2994 if (_vo == VerifyOption_G1UseMarkWord) { 2995 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark())); 2996 } 2997 obj->print_on(gclog_or_tty); 2998 _failures = true; 2999 } 3000 } 3001 } 3002 3003 void do_oop(oop* p) { do_oop_nv(p); } 3004 void do_oop(narrowOop* p) { do_oop_nv(p); } 3005 }; 3006 3007 class G1VerifyCodeRootOopClosure: public OopClosure { 3008 G1CollectedHeap* _g1h; 3009 OopClosure* _root_cl; 3010 nmethod* _nm; 3011 VerifyOption _vo; 3012 bool _failures; 3013 3014 template <class T> void do_oop_work(T* p) { 3015 // First verify that this root is live 3016 _root_cl->do_oop(p); 3017 3018 if (!G1VerifyHeapRegionCodeRoots) { 3019 // We're not verifying the code roots attached to heap region. 3020 return; 3021 } 3022 3023 // Don't check the code roots during marking verification in a full GC 3024 if (_vo == VerifyOption_G1UseMarkWord) { 3025 return; 3026 } 3027 3028 // Now verify that the current nmethod (which contains p) is 3029 // in the code root list of the heap region containing the 3030 // object referenced by p. 3031 3032 T heap_oop = oopDesc::load_heap_oop(p); 3033 if (!oopDesc::is_null(heap_oop)) { 3034 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 3035 3036 // Now fetch the region containing the object 3037 HeapRegion* hr = _g1h->heap_region_containing(obj); 3038 HeapRegionRemSet* hrrs = hr->rem_set(); 3039 // Verify that the strong code root list for this region 3040 // contains the nmethod 3041 if (!hrrs->strong_code_roots_list_contains(_nm)) { 3042 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" " 3043 "from nmethod "PTR_FORMAT" not in strong " 3044 "code roots for region ["PTR_FORMAT","PTR_FORMAT")", 3045 p, _nm, hr->bottom(), hr->end()); 3046 _failures = true; 3047 } 3048 } 3049 } 3050 3051 public: 3052 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo): 3053 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {} 3054 3055 void do_oop(oop* p) { do_oop_work(p); } 3056 void do_oop(narrowOop* p) { do_oop_work(p); } 3057 3058 void set_nmethod(nmethod* nm) { _nm = nm; } 3059 bool failures() { return _failures; } 3060 }; 3061 3062 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure { 3063 G1VerifyCodeRootOopClosure* _oop_cl; 3064 3065 public: 3066 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl): 3067 _oop_cl(oop_cl) {} 3068 3069 void do_code_blob(CodeBlob* cb) { 3070 nmethod* nm = cb->as_nmethod_or_null(); 3071 if (nm != NULL) { 3072 _oop_cl->set_nmethod(nm); 3073 nm->oops_do(_oop_cl); 3074 } 3075 } 3076 }; 3077 3078 class YoungRefCounterClosure : public OopClosure { 3079 G1CollectedHeap* _g1h; 3080 int _count; 3081 public: 3082 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {} 3083 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } } 3084 void do_oop(narrowOop* p) { ShouldNotReachHere(); } 3085 3086 int count() { return _count; } 3087 void reset_count() { _count = 0; }; 3088 }; 3089 3090 class VerifyKlassClosure: public KlassClosure { 3091 YoungRefCounterClosure _young_ref_counter_closure; 3092 OopClosure *_oop_closure; 3093 public: 3094 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {} 3095 void do_klass(Klass* k) { 3096 k->oops_do(_oop_closure); 3097 3098 _young_ref_counter_closure.reset_count(); 3099 k->oops_do(&_young_ref_counter_closure); 3100 if (_young_ref_counter_closure.count() > 0) { 3101 guarantee(k->has_modified_oops(), err_msg("Klass " PTR_FORMAT ", has young refs but is not dirty.", k)); 3102 } 3103 } 3104 }; 3105 3106 class VerifyLivenessOopClosure: public OopClosure { 3107 G1CollectedHeap* _g1h; 3108 VerifyOption _vo; 3109 public: 3110 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo): 3111 _g1h(g1h), _vo(vo) 3112 { } 3113 void do_oop(narrowOop *p) { do_oop_work(p); } 3114 void do_oop( oop *p) { do_oop_work(p); } 3115 3116 template <class T> void do_oop_work(T *p) { 3117 oop obj = oopDesc::load_decode_heap_oop(p); 3118 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo), 3119 "Dead object referenced by a not dead object"); 3120 } 3121 }; 3122 3123 class VerifyObjsInRegionClosure: public ObjectClosure { 3124 private: 3125 G1CollectedHeap* _g1h; 3126 size_t _live_bytes; 3127 HeapRegion *_hr; 3128 VerifyOption _vo; 3129 public: 3130 // _vo == UsePrevMarking -> use "prev" marking information, 3131 // _vo == UseNextMarking -> use "next" marking information, 3132 // _vo == UseMarkWord -> use mark word from object header. 3133 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo) 3134 : _live_bytes(0), _hr(hr), _vo(vo) { 3135 _g1h = G1CollectedHeap::heap(); 3136 } 3137 void do_object(oop o) { 3138 VerifyLivenessOopClosure isLive(_g1h, _vo); 3139 assert(o != NULL, "Huh?"); 3140 if (!_g1h->is_obj_dead_cond(o, _vo)) { 3141 // If the object is alive according to the mark word, 3142 // then verify that the marking information agrees. 3143 // Note we can't verify the contra-positive of the 3144 // above: if the object is dead (according to the mark 3145 // word), it may not be marked, or may have been marked 3146 // but has since became dead, or may have been allocated 3147 // since the last marking. 3148 if (_vo == VerifyOption_G1UseMarkWord) { 3149 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch"); 3150 } 3151 3152 o->oop_iterate_no_header(&isLive); 3153 if (!_hr->obj_allocated_since_prev_marking(o)) { 3154 size_t obj_size = o->size(); // Make sure we don't overflow 3155 _live_bytes += (obj_size * HeapWordSize); 3156 } 3157 } 3158 } 3159 size_t live_bytes() { return _live_bytes; } 3160 }; 3161 3162 class PrintObjsInRegionClosure : public ObjectClosure { 3163 HeapRegion *_hr; 3164 G1CollectedHeap *_g1; 3165 public: 3166 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) { 3167 _g1 = G1CollectedHeap::heap(); 3168 }; 3169 3170 void do_object(oop o) { 3171 if (o != NULL) { 3172 HeapWord *start = (HeapWord *) o; 3173 size_t word_sz = o->size(); 3174 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT 3175 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n", 3176 (void*) o, word_sz, 3177 _g1->isMarkedPrev(o), 3178 _g1->isMarkedNext(o), 3179 _hr->obj_allocated_since_prev_marking(o)); 3180 HeapWord *end = start + word_sz; 3181 HeapWord *cur; 3182 int *val; 3183 for (cur = start; cur < end; cur++) { 3184 val = (int *) cur; 3185 gclog_or_tty->print("\t "PTR_FORMAT":%d\n", val, *val); 3186 } 3187 } 3188 } 3189 }; 3190 3191 class VerifyRegionClosure: public HeapRegionClosure { 3192 private: 3193 bool _par; 3194 VerifyOption _vo; 3195 bool _failures; 3196 public: 3197 // _vo == UsePrevMarking -> use "prev" marking information, 3198 // _vo == UseNextMarking -> use "next" marking information, 3199 // _vo == UseMarkWord -> use mark word from object header. 3200 VerifyRegionClosure(bool par, VerifyOption vo) 3201 : _par(par), 3202 _vo(vo), 3203 _failures(false) {} 3204 3205 bool failures() { 3206 return _failures; 3207 } 3208 3209 bool doHeapRegion(HeapRegion* r) { 3210 if (!r->continuesHumongous()) { 3211 bool failures = false; 3212 r->verify(_vo, &failures); 3213 if (failures) { 3214 _failures = true; 3215 } else { 3216 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo); 3217 r->object_iterate(¬_dead_yet_cl); 3218 if (_vo != VerifyOption_G1UseNextMarking) { 3219 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) { 3220 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] " 3221 "max_live_bytes "SIZE_FORMAT" " 3222 "< calculated "SIZE_FORMAT, 3223 r->bottom(), r->end(), 3224 r->max_live_bytes(), 3225 not_dead_yet_cl.live_bytes()); 3226 _failures = true; 3227 } 3228 } else { 3229 // When vo == UseNextMarking we cannot currently do a sanity 3230 // check on the live bytes as the calculation has not been 3231 // finalized yet. 3232 } 3233 } 3234 } 3235 return false; // stop the region iteration if we hit a failure 3236 } 3237 }; 3238 3239 // This is the task used for parallel verification of the heap regions 3240 3241 class G1ParVerifyTask: public AbstractGangTask { 3242 private: 3243 G1CollectedHeap* _g1h; 3244 VerifyOption _vo; 3245 bool _failures; 3246 3247 public: 3248 // _vo == UsePrevMarking -> use "prev" marking information, 3249 // _vo == UseNextMarking -> use "next" marking information, 3250 // _vo == UseMarkWord -> use mark word from object header. 3251 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) : 3252 AbstractGangTask("Parallel verify task"), 3253 _g1h(g1h), 3254 _vo(vo), 3255 _failures(false) { } 3256 3257 bool failures() { 3258 return _failures; 3259 } 3260 3261 void work(uint worker_id) { 3262 HandleMark hm; 3263 VerifyRegionClosure blk(true, _vo); 3264 _g1h->heap_region_par_iterate_chunked(&blk, worker_id, 3265 _g1h->workers()->active_workers(), 3266 HeapRegion::ParVerifyClaimValue); 3267 if (blk.failures()) { 3268 _failures = true; 3269 } 3270 } 3271 }; 3272 3273 void G1CollectedHeap::verify(bool silent, VerifyOption vo) { 3274 if (SafepointSynchronize::is_at_safepoint()) { 3275 assert(Thread::current()->is_VM_thread(), 3276 "Expected to be executed serially by the VM thread at this point"); 3277 3278 if (!silent) { gclog_or_tty->print("Roots "); } 3279 VerifyRootsClosure rootsCl(vo); 3280 VerifyKlassClosure klassCl(this, &rootsCl); 3281 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false); 3282 3283 // We apply the relevant closures to all the oops in the 3284 // system dictionary, class loader data graph, the string table 3285 // and the nmethods in the code cache. 3286 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo); 3287 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl); 3288 3289 process_all_roots(true, // activate StrongRootsScope 3290 SO_AllCodeCache, // roots scanning options 3291 &rootsCl, 3292 &cldCl, 3293 &blobsCl); 3294 3295 bool failures = rootsCl.failures() || codeRootsCl.failures(); 3296 3297 if (vo != VerifyOption_G1UseMarkWord) { 3298 // If we're verifying during a full GC then the region sets 3299 // will have been torn down at the start of the GC. Therefore 3300 // verifying the region sets will fail. So we only verify 3301 // the region sets when not in a full GC. 3302 if (!silent) { gclog_or_tty->print("HeapRegionSets "); } 3303 verify_region_sets(); 3304 } 3305 3306 if (!silent) { gclog_or_tty->print("HeapRegions "); } 3307 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) { 3308 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue), 3309 "sanity check"); 3310 3311 G1ParVerifyTask task(this, vo); 3312 assert(UseDynamicNumberOfGCThreads || 3313 workers()->active_workers() == workers()->total_workers(), 3314 "If not dynamic should be using all the workers"); 3315 int n_workers = workers()->active_workers(); 3316 set_par_threads(n_workers); 3317 workers()->run_task(&task); 3318 set_par_threads(0); 3319 if (task.failures()) { 3320 failures = true; 3321 } 3322 3323 // Checks that the expected amount of parallel work was done. 3324 // The implication is that n_workers is > 0. 3325 assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue), 3326 "sanity check"); 3327 3328 reset_heap_region_claim_values(); 3329 3330 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue), 3331 "sanity check"); 3332 } else { 3333 VerifyRegionClosure blk(false, vo); 3334 heap_region_iterate(&blk); 3335 if (blk.failures()) { 3336 failures = true; 3337 } 3338 } 3339 if (!silent) gclog_or_tty->print("RemSet "); 3340 rem_set()->verify(); 3341 3342 if (G1StringDedup::is_enabled()) { 3343 if (!silent) gclog_or_tty->print("StrDedup "); 3344 G1StringDedup::verify(); 3345 } 3346 3347 if (failures) { 3348 gclog_or_tty->print_cr("Heap:"); 3349 // It helps to have the per-region information in the output to 3350 // help us track down what went wrong. This is why we call 3351 // print_extended_on() instead of print_on(). 3352 print_extended_on(gclog_or_tty); 3353 gclog_or_tty->cr(); 3354 #ifndef PRODUCT 3355 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) { 3356 concurrent_mark()->print_reachable("at-verification-failure", 3357 vo, false /* all */); 3358 } 3359 #endif 3360 gclog_or_tty->flush(); 3361 } 3362 guarantee(!failures, "there should not have been any failures"); 3363 } else { 3364 if (!silent) { 3365 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet"); 3366 if (G1StringDedup::is_enabled()) { 3367 gclog_or_tty->print(", StrDedup"); 3368 } 3369 gclog_or_tty->print(") "); 3370 } 3371 } 3372 } 3373 3374 void G1CollectedHeap::verify(bool silent) { 3375 verify(silent, VerifyOption_G1UsePrevMarking); 3376 } 3377 3378 double G1CollectedHeap::verify(bool guard, const char* msg) { 3379 double verify_time_ms = 0.0; 3380 3381 if (guard && total_collections() >= VerifyGCStartAt) { 3382 double verify_start = os::elapsedTime(); 3383 HandleMark hm; // Discard invalid handles created during verification 3384 prepare_for_verify(); 3385 Universe::verify(VerifyOption_G1UsePrevMarking, msg); 3386 verify_time_ms = (os::elapsedTime() - verify_start) * 1000; 3387 } 3388 3389 return verify_time_ms; 3390 } 3391 3392 void G1CollectedHeap::verify_before_gc() { 3393 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:"); 3394 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms); 3395 } 3396 3397 void G1CollectedHeap::verify_after_gc() { 3398 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:"); 3399 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms); 3400 } 3401 3402 class PrintRegionClosure: public HeapRegionClosure { 3403 outputStream* _st; 3404 public: 3405 PrintRegionClosure(outputStream* st) : _st(st) {} 3406 bool doHeapRegion(HeapRegion* r) { 3407 r->print_on(_st); 3408 return false; 3409 } 3410 }; 3411 3412 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 3413 const HeapRegion* hr, 3414 const VerifyOption vo) const { 3415 switch (vo) { 3416 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); 3417 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); 3418 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked(); 3419 default: ShouldNotReachHere(); 3420 } 3421 return false; // keep some compilers happy 3422 } 3423 3424 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 3425 const VerifyOption vo) const { 3426 switch (vo) { 3427 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); 3428 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); 3429 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked(); 3430 default: ShouldNotReachHere(); 3431 } 3432 return false; // keep some compilers happy 3433 } 3434 3435 void G1CollectedHeap::print_on(outputStream* st) const { 3436 st->print(" %-20s", "garbage-first heap"); 3437 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 3438 capacity()/K, used_unlocked()/K); 3439 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")", 3440 _hrs.reserved().start(), 3441 _hrs.reserved().start() + _hrs.length() + HeapRegion::GrainWords, 3442 _hrs.reserved().end()); 3443 st->cr(); 3444 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); 3445 uint young_regions = _young_list->length(); 3446 st->print("%u young (" SIZE_FORMAT "K), ", young_regions, 3447 (size_t) young_regions * HeapRegion::GrainBytes / K); 3448 uint survivor_regions = g1_policy()->recorded_survivor_regions(); 3449 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, 3450 (size_t) survivor_regions * HeapRegion::GrainBytes / K); 3451 st->cr(); 3452 MetaspaceAux::print_on(st); 3453 } 3454 3455 void G1CollectedHeap::print_extended_on(outputStream* st) const { 3456 print_on(st); 3457 3458 // Print the per-region information. 3459 st->cr(); 3460 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), " 3461 "HS=humongous(starts), HC=humongous(continues), " 3462 "CS=collection set, F=free, TS=gc time stamp, " 3463 "PTAMS=previous top-at-mark-start, " 3464 "NTAMS=next top-at-mark-start)"); 3465 PrintRegionClosure blk(st); 3466 heap_region_iterate(&blk); 3467 } 3468 3469 void G1CollectedHeap::print_on_error(outputStream* st) const { 3470 this->CollectedHeap::print_on_error(st); 3471 3472 if (_cm != NULL) { 3473 st->cr(); 3474 _cm->print_on_error(st); 3475 } 3476 } 3477 3478 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const { 3479 if (G1CollectedHeap::use_parallel_gc_threads()) { 3480 workers()->print_worker_threads_on(st); 3481 } 3482 _cmThread->print_on(st); 3483 st->cr(); 3484 _cm->print_worker_threads_on(st); 3485 _cg1r->print_worker_threads_on(st); 3486 if (G1StringDedup::is_enabled()) { 3487 G1StringDedup::print_worker_threads_on(st); 3488 } 3489 } 3490 3491 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { 3492 if (G1CollectedHeap::use_parallel_gc_threads()) { 3493 workers()->threads_do(tc); 3494 } 3495 tc->do_thread(_cmThread); 3496 _cg1r->threads_do(tc); 3497 if (G1StringDedup::is_enabled()) { 3498 G1StringDedup::threads_do(tc); 3499 } 3500 } 3501 3502 void G1CollectedHeap::print_tracing_info() const { 3503 // We'll overload this to mean "trace GC pause statistics." 3504 if (TraceYoungGenTime || TraceOldGenTime) { 3505 // The "G1CollectorPolicy" is keeping track of these stats, so delegate 3506 // to that. 3507 g1_policy()->print_tracing_info(); 3508 } 3509 if (G1SummarizeRSetStats) { 3510 g1_rem_set()->print_summary_info(); 3511 } 3512 if (G1SummarizeConcMark) { 3513 concurrent_mark()->print_summary_info(); 3514 } 3515 g1_policy()->print_yg_surv_rate_info(); 3516 SpecializationStats::print(); 3517 } 3518 3519 #ifndef PRODUCT 3520 // Helpful for debugging RSet issues. 3521 3522 class PrintRSetsClosure : public HeapRegionClosure { 3523 private: 3524 const char* _msg; 3525 size_t _occupied_sum; 3526 3527 public: 3528 bool doHeapRegion(HeapRegion* r) { 3529 HeapRegionRemSet* hrrs = r->rem_set(); 3530 size_t occupied = hrrs->occupied(); 3531 _occupied_sum += occupied; 3532 3533 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT, 3534 HR_FORMAT_PARAMS(r)); 3535 if (occupied == 0) { 3536 gclog_or_tty->print_cr(" RSet is empty"); 3537 } else { 3538 hrrs->print(); 3539 } 3540 gclog_or_tty->print_cr("----------"); 3541 return false; 3542 } 3543 3544 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { 3545 gclog_or_tty->cr(); 3546 gclog_or_tty->print_cr("========================================"); 3547 gclog_or_tty->print_cr("%s", msg); 3548 gclog_or_tty->cr(); 3549 } 3550 3551 ~PrintRSetsClosure() { 3552 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum); 3553 gclog_or_tty->print_cr("========================================"); 3554 gclog_or_tty->cr(); 3555 } 3556 }; 3557 3558 void G1CollectedHeap::print_cset_rsets() { 3559 PrintRSetsClosure cl("Printing CSet RSets"); 3560 collection_set_iterate(&cl); 3561 } 3562 3563 void G1CollectedHeap::print_all_rsets() { 3564 PrintRSetsClosure cl("Printing All RSets");; 3565 heap_region_iterate(&cl); 3566 } 3567 #endif // PRODUCT 3568 3569 G1CollectedHeap* G1CollectedHeap::heap() { 3570 assert(_sh->kind() == CollectedHeap::G1CollectedHeap, 3571 "not a garbage-first heap"); 3572 return _g1h; 3573 } 3574 3575 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) { 3576 // always_do_update_barrier = false; 3577 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 3578 // Fill TLAB's and such 3579 accumulate_statistics_all_tlabs(); 3580 ensure_parsability(true); 3581 3582 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) && 3583 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) { 3584 g1_rem_set()->print_periodic_summary_info("Before GC RS summary"); 3585 } 3586 } 3587 3588 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) { 3589 3590 if (G1SummarizeRSetStats && 3591 (G1SummarizeRSetStatsPeriod > 0) && 3592 // we are at the end of the GC. Total collections has already been increased. 3593 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) { 3594 g1_rem_set()->print_periodic_summary_info("After GC RS summary"); 3595 } 3596 3597 // FIXME: what is this about? 3598 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" 3599 // is set. 3600 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(), 3601 "derived pointer present")); 3602 // always_do_update_barrier = true; 3603 3604 resize_all_tlabs(); 3605 3606 // We have just completed a GC. Update the soft reference 3607 // policy with the new heap occupancy 3608 Universe::update_heap_info_at_gc(); 3609 } 3610 3611 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, 3612 unsigned int gc_count_before, 3613 bool* succeeded, 3614 GCCause::Cause gc_cause) { 3615 assert_heap_not_locked_and_not_at_safepoint(); 3616 g1_policy()->record_stop_world_start(); 3617 VM_G1IncCollectionPause op(gc_count_before, 3618 word_size, 3619 false, /* should_initiate_conc_mark */ 3620 g1_policy()->max_pause_time_ms(), 3621 gc_cause); 3622 VMThread::execute(&op); 3623 3624 HeapWord* result = op.result(); 3625 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded(); 3626 assert(result == NULL || ret_succeeded, 3627 "the result should be NULL if the VM did not succeed"); 3628 *succeeded = ret_succeeded; 3629 3630 assert_heap_not_locked(); 3631 return result; 3632 } 3633 3634 void 3635 G1CollectedHeap::doConcurrentMark() { 3636 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); 3637 if (!_cmThread->in_progress()) { 3638 _cmThread->set_started(); 3639 CGC_lock->notify(); 3640 } 3641 } 3642 3643 size_t G1CollectedHeap::pending_card_num() { 3644 size_t extra_cards = 0; 3645 JavaThread *curr = Threads::first(); 3646 while (curr != NULL) { 3647 DirtyCardQueue& dcq = curr->dirty_card_queue(); 3648 extra_cards += dcq.size(); 3649 curr = curr->next(); 3650 } 3651 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 3652 size_t buffer_size = dcqs.buffer_size(); 3653 size_t buffer_num = dcqs.completed_buffers_num(); 3654 3655 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes 3656 // in bytes - not the number of 'entries'. We need to convert 3657 // into a number of cards. 3658 return (buffer_size * buffer_num + extra_cards) / oopSize; 3659 } 3660 3661 size_t G1CollectedHeap::cards_scanned() { 3662 return g1_rem_set()->cardsScanned(); 3663 } 3664 3665 bool G1CollectedHeap::humongous_region_is_always_live(uint index) { 3666 HeapRegion* region = region_at(index); 3667 assert(region->startsHumongous(), "Must start a humongous object"); 3668 return oop(region->bottom())->is_objArray() || !region->rem_set()->is_empty(); 3669 } 3670 3671 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure { 3672 private: 3673 size_t _total_humongous; 3674 size_t _candidate_humongous; 3675 public: 3676 RegisterHumongousWithInCSetFastTestClosure() : _total_humongous(0), _candidate_humongous(0) { 3677 } 3678 3679 virtual bool doHeapRegion(HeapRegion* r) { 3680 if (!r->startsHumongous()) { 3681 return false; 3682 } 3683 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 3684 3685 uint region_idx = r->hrs_index(); 3686 bool is_candidate = !g1h->humongous_region_is_always_live(region_idx); 3687 // Is_candidate already filters out humongous regions with some remembered set. 3688 // This will not lead to humongous object that we mistakenly keep alive because 3689 // during young collection the remembered sets will only be added to. 3690 if (is_candidate) { 3691 g1h->register_humongous_region_with_in_cset_fast_test(region_idx); 3692 _candidate_humongous++; 3693 } 3694 _total_humongous++; 3695 3696 return false; 3697 } 3698 3699 size_t total_humongous() const { return _total_humongous; } 3700 size_t candidate_humongous() const { return _candidate_humongous; } 3701 }; 3702 3703 void G1CollectedHeap::register_humongous_regions_with_in_cset_fast_test() { 3704 if (!G1ReclaimDeadHumongousObjectsAtYoungGC) { 3705 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0, 0); 3706 return; 3707 } 3708 3709 RegisterHumongousWithInCSetFastTestClosure cl; 3710 heap_region_iterate(&cl); 3711 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(cl.total_humongous(), 3712 cl.candidate_humongous()); 3713 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0; 3714 3715 if (_has_humongous_reclaim_candidates) { 3716 clear_humongous_is_live_table(); 3717 } 3718 } 3719 3720 void 3721 G1CollectedHeap::setup_surviving_young_words() { 3722 assert(_surviving_young_words == NULL, "pre-condition"); 3723 uint array_length = g1_policy()->young_cset_region_length(); 3724 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC); 3725 if (_surviving_young_words == NULL) { 3726 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR, 3727 "Not enough space for young surv words summary."); 3728 } 3729 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t)); 3730 #ifdef ASSERT 3731 for (uint i = 0; i < array_length; ++i) { 3732 assert( _surviving_young_words[i] == 0, "memset above" ); 3733 } 3734 #endif // !ASSERT 3735 } 3736 3737 void 3738 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) { 3739 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); 3740 uint array_length = g1_policy()->young_cset_region_length(); 3741 for (uint i = 0; i < array_length; ++i) { 3742 _surviving_young_words[i] += surv_young_words[i]; 3743 } 3744 } 3745 3746 void 3747 G1CollectedHeap::cleanup_surviving_young_words() { 3748 guarantee( _surviving_young_words != NULL, "pre-condition" ); 3749 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words, mtGC); 3750 _surviving_young_words = NULL; 3751 } 3752 3753 #ifdef ASSERT 3754 class VerifyCSetClosure: public HeapRegionClosure { 3755 public: 3756 bool doHeapRegion(HeapRegion* hr) { 3757 // Here we check that the CSet region's RSet is ready for parallel 3758 // iteration. The fields that we'll verify are only manipulated 3759 // when the region is part of a CSet and is collected. Afterwards, 3760 // we reset these fields when we clear the region's RSet (when the 3761 // region is freed) so they are ready when the region is 3762 // re-allocated. The only exception to this is if there's an 3763 // evacuation failure and instead of freeing the region we leave 3764 // it in the heap. In that case, we reset these fields during 3765 // evacuation failure handling. 3766 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification"); 3767 3768 // Here's a good place to add any other checks we'd like to 3769 // perform on CSet regions. 3770 return false; 3771 } 3772 }; 3773 #endif // ASSERT 3774 3775 #if TASKQUEUE_STATS 3776 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) { 3777 st->print_raw_cr("GC Task Stats"); 3778 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); 3779 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); 3780 } 3781 3782 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const { 3783 print_taskqueue_stats_hdr(st); 3784 3785 TaskQueueStats totals; 3786 const int n = workers() != NULL ? workers()->total_workers() : 1; 3787 for (int i = 0; i < n; ++i) { 3788 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr(); 3789 totals += task_queue(i)->stats; 3790 } 3791 st->print_raw("tot "); totals.print(st); st->cr(); 3792 3793 DEBUG_ONLY(totals.verify()); 3794 } 3795 3796 void G1CollectedHeap::reset_taskqueue_stats() { 3797 const int n = workers() != NULL ? workers()->total_workers() : 1; 3798 for (int i = 0; i < n; ++i) { 3799 task_queue(i)->stats.reset(); 3800 } 3801 } 3802 #endif // TASKQUEUE_STATS 3803 3804 void G1CollectedHeap::log_gc_header() { 3805 if (!G1Log::fine()) { 3806 return; 3807 } 3808 3809 gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id()); 3810 3811 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause()) 3812 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)") 3813 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : ""); 3814 3815 gclog_or_tty->print("[%s", (const char*)gc_cause_str); 3816 } 3817 3818 void G1CollectedHeap::log_gc_footer(double pause_time_sec) { 3819 if (!G1Log::fine()) { 3820 return; 3821 } 3822 3823 if (G1Log::finer()) { 3824 if (evacuation_failed()) { 3825 gclog_or_tty->print(" (to-space exhausted)"); 3826 } 3827 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec); 3828 g1_policy()->phase_times()->note_gc_end(); 3829 g1_policy()->phase_times()->print(pause_time_sec); 3830 g1_policy()->print_detailed_heap_transition(); 3831 } else { 3832 if (evacuation_failed()) { 3833 gclog_or_tty->print("--"); 3834 } 3835 g1_policy()->print_heap_transition(); 3836 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec); 3837 } 3838 gclog_or_tty->flush(); 3839 } 3840 3841 bool 3842 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { 3843 assert_at_safepoint(true /* should_be_vm_thread */); 3844 guarantee(!is_gc_active(), "collection is not reentrant"); 3845 3846 if (GC_locker::check_active_before_gc()) { 3847 return false; 3848 } 3849 3850 _gc_timer_stw->register_gc_start(); 3851 3852 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start()); 3853 3854 SvcGCMarker sgcm(SvcGCMarker::MINOR); 3855 ResourceMark rm; 3856 3857 print_heap_before_gc(); 3858 trace_heap_before_gc(_gc_tracer_stw); 3859 3860 verify_region_sets_optional(); 3861 verify_dirty_young_regions(); 3862 3863 // This call will decide whether this pause is an initial-mark 3864 // pause. If it is, during_initial_mark_pause() will return true 3865 // for the duration of this pause. 3866 g1_policy()->decide_on_conc_mark_initiation(); 3867 3868 // We do not allow initial-mark to be piggy-backed on a mixed GC. 3869 assert(!g1_policy()->during_initial_mark_pause() || 3870 g1_policy()->gcs_are_young(), "sanity"); 3871 3872 // We also do not allow mixed GCs during marking. 3873 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity"); 3874 3875 // Record whether this pause is an initial mark. When the current 3876 // thread has completed its logging output and it's safe to signal 3877 // the CM thread, the flag's value in the policy has been reset. 3878 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause(); 3879 3880 // Inner scope for scope based logging, timers, and stats collection 3881 { 3882 EvacuationInfo evacuation_info; 3883 3884 if (g1_policy()->during_initial_mark_pause()) { 3885 // We are about to start a marking cycle, so we increment the 3886 // full collection counter. 3887 increment_old_marking_cycles_started(); 3888 register_concurrent_cycle_start(_gc_timer_stw->gc_start()); 3889 } 3890 3891 _gc_tracer_stw->report_yc_type(yc_type()); 3892 3893 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty); 3894 3895 int active_workers = (G1CollectedHeap::use_parallel_gc_threads() ? 3896 workers()->active_workers() : 1); 3897 double pause_start_sec = os::elapsedTime(); 3898 g1_policy()->phase_times()->note_gc_start(active_workers); 3899 log_gc_header(); 3900 3901 TraceCollectorStats tcs(g1mm()->incremental_collection_counters()); 3902 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause()); 3903 3904 // If the secondary_free_list is not empty, append it to the 3905 // free_list. No need to wait for the cleanup operation to finish; 3906 // the region allocation code will check the secondary_free_list 3907 // and wait if necessary. If the G1StressConcRegionFreeing flag is 3908 // set, skip this step so that the region allocation code has to 3909 // get entries from the secondary_free_list. 3910 if (!G1StressConcRegionFreeing) { 3911 append_secondary_free_list_if_not_empty_with_lock(); 3912 } 3913 3914 assert(check_young_list_well_formed(), "young list should be well formed"); 3915 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue), 3916 "sanity check"); 3917 3918 // Don't dynamically change the number of GC threads this early. A value of 3919 // 0 is used to indicate serial work. When parallel work is done, 3920 // it will be set. 3921 3922 { // Call to jvmpi::post_class_unload_events must occur outside of active GC 3923 IsGCActiveMark x; 3924 3925 gc_prologue(false); 3926 increment_total_collections(false /* full gc */); 3927 increment_gc_time_stamp(); 3928 3929 verify_before_gc(); 3930 3931 check_bitmaps("GC Start"); 3932 3933 COMPILER2_PRESENT(DerivedPointerTable::clear()); 3934 3935 // Please see comment in g1CollectedHeap.hpp and 3936 // G1CollectedHeap::ref_processing_init() to see how 3937 // reference processing currently works in G1. 3938 3939 // Enable discovery in the STW reference processor 3940 ref_processor_stw()->enable_discovery(true /*verify_disabled*/, 3941 true /*verify_no_refs*/); 3942 3943 { 3944 // We want to temporarily turn off discovery by the 3945 // CM ref processor, if necessary, and turn it back on 3946 // on again later if we do. Using a scoped 3947 // NoRefDiscovery object will do this. 3948 NoRefDiscovery no_cm_discovery(ref_processor_cm()); 3949 3950 // Forget the current alloc region (we might even choose it to be part 3951 // of the collection set!). 3952 release_mutator_alloc_region(); 3953 3954 // We should call this after we retire the mutator alloc 3955 // region(s) so that all the ALLOC / RETIRE events are generated 3956 // before the start GC event. 3957 _hr_printer.start_gc(false /* full */, (size_t) total_collections()); 3958 3959 // This timing is only used by the ergonomics to handle our pause target. 3960 // It is unclear why this should not include the full pause. We will 3961 // investigate this in CR 7178365. 3962 // 3963 // Preserving the old comment here if that helps the investigation: 3964 // 3965 // The elapsed time induced by the start time below deliberately elides 3966 // the possible verification above. 3967 double sample_start_time_sec = os::elapsedTime(); 3968 3969 #if YOUNG_LIST_VERBOSE 3970 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:"); 3971 _young_list->print(); 3972 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 3973 #endif // YOUNG_LIST_VERBOSE 3974 3975 g1_policy()->record_collection_pause_start(sample_start_time_sec); 3976 3977 double scan_wait_start = os::elapsedTime(); 3978 // We have to wait until the CM threads finish scanning the 3979 // root regions as it's the only way to ensure that all the 3980 // objects on them have been correctly scanned before we start 3981 // moving them during the GC. 3982 bool waited = _cm->root_regions()->wait_until_scan_finished(); 3983 double wait_time_ms = 0.0; 3984 if (waited) { 3985 double scan_wait_end = os::elapsedTime(); 3986 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0; 3987 } 3988 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms); 3989 3990 #if YOUNG_LIST_VERBOSE 3991 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:"); 3992 _young_list->print(); 3993 #endif // YOUNG_LIST_VERBOSE 3994 3995 if (g1_policy()->during_initial_mark_pause()) { 3996 concurrent_mark()->checkpointRootsInitialPre(); 3997 } 3998 3999 #if YOUNG_LIST_VERBOSE 4000 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:"); 4001 _young_list->print(); 4002 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 4003 #endif // YOUNG_LIST_VERBOSE 4004 4005 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info); 4006 4007 register_humongous_regions_with_in_cset_fast_test(); 4008 4009 _cm->note_start_of_gc(); 4010 // We should not verify the per-thread SATB buffers given that 4011 // we have not filtered them yet (we'll do so during the 4012 // GC). We also call this after finalize_cset() to 4013 // ensure that the CSet has been finalized. 4014 _cm->verify_no_cset_oops(true /* verify_stacks */, 4015 true /* verify_enqueued_buffers */, 4016 false /* verify_thread_buffers */, 4017 true /* verify_fingers */); 4018 4019 if (_hr_printer.is_active()) { 4020 HeapRegion* hr = g1_policy()->collection_set(); 4021 while (hr != NULL) { 4022 G1HRPrinter::RegionType type; 4023 if (!hr->is_young()) { 4024 type = G1HRPrinter::Old; 4025 } else if (hr->is_survivor()) { 4026 type = G1HRPrinter::Survivor; 4027 } else { 4028 type = G1HRPrinter::Eden; 4029 } 4030 _hr_printer.cset(hr); 4031 hr = hr->next_in_collection_set(); 4032 } 4033 } 4034 4035 #ifdef ASSERT 4036 VerifyCSetClosure cl; 4037 collection_set_iterate(&cl); 4038 #endif // ASSERT 4039 4040 setup_surviving_young_words(); 4041 4042 // Initialize the GC alloc regions. 4043 init_gc_alloc_regions(evacuation_info); 4044 4045 // Actually do the work... 4046 evacuate_collection_set(evacuation_info); 4047 4048 // We do this to mainly verify the per-thread SATB buffers 4049 // (which have been filtered by now) since we didn't verify 4050 // them earlier. No point in re-checking the stacks / enqueued 4051 // buffers given that the CSet has not changed since last time 4052 // we checked. 4053 _cm->verify_no_cset_oops(false /* verify_stacks */, 4054 false /* verify_enqueued_buffers */, 4055 true /* verify_thread_buffers */, 4056 true /* verify_fingers */); 4057 4058 free_collection_set(g1_policy()->collection_set(), evacuation_info); 4059 4060 eagerly_reclaim_humongous_regions(); 4061 4062 g1_policy()->clear_collection_set(); 4063 4064 cleanup_surviving_young_words(); 4065 4066 // Start a new incremental collection set for the next pause. 4067 g1_policy()->start_incremental_cset_building(); 4068 4069 clear_cset_fast_test(); 4070 4071 _young_list->reset_sampled_info(); 4072 4073 // Don't check the whole heap at this point as the 4074 // GC alloc regions from this pause have been tagged 4075 // as survivors and moved on to the survivor list. 4076 // Survivor regions will fail the !is_young() check. 4077 assert(check_young_list_empty(false /* check_heap */), 4078 "young list should be empty"); 4079 4080 #if YOUNG_LIST_VERBOSE 4081 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:"); 4082 _young_list->print(); 4083 #endif // YOUNG_LIST_VERBOSE 4084 4085 g1_policy()->record_survivor_regions(_young_list->survivor_length(), 4086 _young_list->first_survivor_region(), 4087 _young_list->last_survivor_region()); 4088 4089 _young_list->reset_auxilary_lists(); 4090 4091 if (evacuation_failed()) { 4092 _summary_bytes_used = recalculate_used(); 4093 uint n_queues = MAX2((int)ParallelGCThreads, 1); 4094 for (uint i = 0; i < n_queues; i++) { 4095 if (_evacuation_failed_info_array[i].has_failed()) { 4096 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]); 4097 } 4098 } 4099 } else { 4100 // The "used" of the the collection set have already been subtracted 4101 // when they were freed. Add in the bytes evacuated. 4102 _summary_bytes_used += g1_policy()->bytes_copied_during_gc(); 4103 } 4104 4105 if (g1_policy()->during_initial_mark_pause()) { 4106 // We have to do this before we notify the CM threads that 4107 // they can start working to make sure that all the 4108 // appropriate initialization is done on the CM object. 4109 concurrent_mark()->checkpointRootsInitialPost(); 4110 set_marking_started(); 4111 // Note that we don't actually trigger the CM thread at 4112 // this point. We do that later when we're sure that 4113 // the current thread has completed its logging output. 4114 } 4115 4116 allocate_dummy_regions(); 4117 4118 #if YOUNG_LIST_VERBOSE 4119 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:"); 4120 _young_list->print(); 4121 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 4122 #endif // YOUNG_LIST_VERBOSE 4123 4124 init_mutator_alloc_region(); 4125 4126 { 4127 size_t expand_bytes = g1_policy()->expansion_amount(); 4128 if (expand_bytes > 0) { 4129 size_t bytes_before = capacity(); 4130 // No need for an ergo verbose message here, 4131 // expansion_amount() does this when it returns a value > 0. 4132 if (!expand(expand_bytes)) { 4133 // We failed to expand the heap. Cannot do anything about it. 4134 } 4135 } 4136 } 4137 4138 // We redo the verification but now wrt to the new CSet which 4139 // has just got initialized after the previous CSet was freed. 4140 _cm->verify_no_cset_oops(true /* verify_stacks */, 4141 true /* verify_enqueued_buffers */, 4142 true /* verify_thread_buffers */, 4143 true /* verify_fingers */); 4144 _cm->note_end_of_gc(); 4145 4146 // This timing is only used by the ergonomics to handle our pause target. 4147 // It is unclear why this should not include the full pause. We will 4148 // investigate this in CR 7178365. 4149 double sample_end_time_sec = os::elapsedTime(); 4150 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; 4151 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info); 4152 4153 MemoryService::track_memory_usage(); 4154 4155 // In prepare_for_verify() below we'll need to scan the deferred 4156 // update buffers to bring the RSets up-to-date if 4157 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning 4158 // the update buffers we'll probably need to scan cards on the 4159 // regions we just allocated to (i.e., the GC alloc 4160 // regions). However, during the last GC we called 4161 // set_saved_mark() on all the GC alloc regions, so card 4162 // scanning might skip the [saved_mark_word()...top()] area of 4163 // those regions (i.e., the area we allocated objects into 4164 // during the last GC). But it shouldn't. Given that 4165 // saved_mark_word() is conditional on whether the GC time stamp 4166 // on the region is current or not, by incrementing the GC time 4167 // stamp here we invalidate all the GC time stamps on all the 4168 // regions and saved_mark_word() will simply return top() for 4169 // all the regions. This is a nicer way of ensuring this rather 4170 // than iterating over the regions and fixing them. In fact, the 4171 // GC time stamp increment here also ensures that 4172 // saved_mark_word() will return top() between pauses, i.e., 4173 // during concurrent refinement. So we don't need the 4174 // is_gc_active() check to decided which top to use when 4175 // scanning cards (see CR 7039627). 4176 increment_gc_time_stamp(); 4177 4178 verify_after_gc(); 4179 check_bitmaps("GC End"); 4180 4181 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 4182 ref_processor_stw()->verify_no_references_recorded(); 4183 4184 // CM reference discovery will be re-enabled if necessary. 4185 } 4186 4187 // We should do this after we potentially expand the heap so 4188 // that all the COMMIT events are generated before the end GC 4189 // event, and after we retire the GC alloc regions so that all 4190 // RETIRE events are generated before the end GC event. 4191 _hr_printer.end_gc(false /* full */, (size_t) total_collections()); 4192 4193 #ifdef TRACESPINNING 4194 ParallelTaskTerminator::print_termination_counts(); 4195 #endif 4196 4197 gc_epilogue(false); 4198 } 4199 4200 // Print the remainder of the GC log output. 4201 log_gc_footer(os::elapsedTime() - pause_start_sec); 4202 4203 // It is not yet to safe to tell the concurrent mark to 4204 // start as we have some optional output below. We don't want the 4205 // output from the concurrent mark thread interfering with this 4206 // logging output either. 4207 4208 _hrs.verify_optional(); 4209 verify_region_sets_optional(); 4210 4211 TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats()); 4212 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); 4213 4214 print_heap_after_gc(); 4215 trace_heap_after_gc(_gc_tracer_stw); 4216 4217 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 4218 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 4219 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 4220 // before any GC notifications are raised. 4221 g1mm()->update_sizes(); 4222 4223 _gc_tracer_stw->report_evacuation_info(&evacuation_info); 4224 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold()); 4225 _gc_timer_stw->register_gc_end(); 4226 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions()); 4227 } 4228 // It should now be safe to tell the concurrent mark thread to start 4229 // without its logging output interfering with the logging output 4230 // that came from the pause. 4231 4232 if (should_start_conc_mark) { 4233 // CAUTION: after the doConcurrentMark() call below, 4234 // the concurrent marking thread(s) could be running 4235 // concurrently with us. Make sure that anything after 4236 // this point does not assume that we are the only GC thread 4237 // running. Note: of course, the actual marking work will 4238 // not start until the safepoint itself is released in 4239 // SuspendibleThreadSet::desynchronize(). 4240 doConcurrentMark(); 4241 } 4242 4243 return true; 4244 } 4245 4246 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose) 4247 { 4248 size_t gclab_word_size; 4249 switch (purpose) { 4250 case GCAllocForSurvived: 4251 gclab_word_size = _survivor_plab_stats.desired_plab_sz(); 4252 break; 4253 case GCAllocForTenured: 4254 gclab_word_size = _old_plab_stats.desired_plab_sz(); 4255 break; 4256 default: 4257 assert(false, "unknown GCAllocPurpose"); 4258 gclab_word_size = _old_plab_stats.desired_plab_sz(); 4259 break; 4260 } 4261 4262 // Prevent humongous PLAB sizes for two reasons: 4263 // * PLABs are allocated using a similar paths as oops, but should 4264 // never be in a humongous region 4265 // * Allowing humongous PLABs needlessly churns the region free lists 4266 return MIN2(_humongous_object_threshold_in_words, gclab_word_size); 4267 } 4268 4269 void G1CollectedHeap::init_mutator_alloc_region() { 4270 assert(_mutator_alloc_region.get() == NULL, "pre-condition"); 4271 _mutator_alloc_region.init(); 4272 } 4273 4274 void G1CollectedHeap::release_mutator_alloc_region() { 4275 _mutator_alloc_region.release(); 4276 assert(_mutator_alloc_region.get() == NULL, "post-condition"); 4277 } 4278 4279 void G1CollectedHeap::use_retained_old_gc_alloc_region(EvacuationInfo& evacuation_info) { 4280 HeapRegion* retained_region = _retained_old_gc_alloc_region; 4281 _retained_old_gc_alloc_region = NULL; 4282 4283 // We will discard the current GC alloc region if: 4284 // a) it's in the collection set (it can happen!), 4285 // b) it's already full (no point in using it), 4286 // c) it's empty (this means that it was emptied during 4287 // a cleanup and it should be on the free list now), or 4288 // d) it's humongous (this means that it was emptied 4289 // during a cleanup and was added to the free list, but 4290 // has been subsequently used to allocate a humongous 4291 // object that may be less than the region size). 4292 if (retained_region != NULL && 4293 !retained_region->in_collection_set() && 4294 !(retained_region->top() == retained_region->end()) && 4295 !retained_region->is_empty() && 4296 !retained_region->isHumongous()) { 4297 retained_region->record_top_and_timestamp(); 4298 // The retained region was added to the old region set when it was 4299 // retired. We have to remove it now, since we don't allow regions 4300 // we allocate to in the region sets. We'll re-add it later, when 4301 // it's retired again. 4302 _old_set.remove(retained_region); 4303 bool during_im = g1_policy()->during_initial_mark_pause(); 4304 retained_region->note_start_of_copying(during_im); 4305 _old_gc_alloc_region.set(retained_region); 4306 _hr_printer.reuse(retained_region); 4307 evacuation_info.set_alloc_regions_used_before(retained_region->used()); 4308 } 4309 } 4310 4311 void G1CollectedHeap::init_gc_alloc_regions(EvacuationInfo& evacuation_info) { 4312 assert_at_safepoint(true /* should_be_vm_thread */); 4313 4314 _survivor_gc_alloc_region.init(); 4315 _old_gc_alloc_region.init(); 4316 4317 use_retained_old_gc_alloc_region(evacuation_info); 4318 } 4319 4320 void G1CollectedHeap::release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info) { 4321 evacuation_info.set_allocation_regions(_survivor_gc_alloc_region.count() + 4322 _old_gc_alloc_region.count()); 4323 _survivor_gc_alloc_region.release(); 4324 // If we have an old GC alloc region to release, we'll save it in 4325 // _retained_old_gc_alloc_region. If we don't 4326 // _retained_old_gc_alloc_region will become NULL. This is what we 4327 // want either way so no reason to check explicitly for either 4328 // condition. 4329 _retained_old_gc_alloc_region = _old_gc_alloc_region.release(); 4330 4331 if (ResizePLAB) { 4332 _survivor_plab_stats.adjust_desired_plab_sz(no_of_gc_workers); 4333 _old_plab_stats.adjust_desired_plab_sz(no_of_gc_workers); 4334 } 4335 } 4336 4337 void G1CollectedHeap::abandon_gc_alloc_regions() { 4338 assert(_survivor_gc_alloc_region.get() == NULL, "pre-condition"); 4339 assert(_old_gc_alloc_region.get() == NULL, "pre-condition"); 4340 _retained_old_gc_alloc_region = NULL; 4341 } 4342 4343 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) { 4344 _drain_in_progress = false; 4345 set_evac_failure_closure(cl); 4346 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true); 4347 } 4348 4349 void G1CollectedHeap::finalize_for_evac_failure() { 4350 assert(_evac_failure_scan_stack != NULL && 4351 _evac_failure_scan_stack->length() == 0, 4352 "Postcondition"); 4353 assert(!_drain_in_progress, "Postcondition"); 4354 delete _evac_failure_scan_stack; 4355 _evac_failure_scan_stack = NULL; 4356 } 4357 4358 void G1CollectedHeap::remove_self_forwarding_pointers() { 4359 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity"); 4360 4361 double remove_self_forwards_start = os::elapsedTime(); 4362 4363 G1ParRemoveSelfForwardPtrsTask rsfp_task(this); 4364 4365 if (G1CollectedHeap::use_parallel_gc_threads()) { 4366 set_par_threads(); 4367 workers()->run_task(&rsfp_task); 4368 set_par_threads(0); 4369 } else { 4370 rsfp_task.work(0); 4371 } 4372 4373 assert(check_cset_heap_region_claim_values(HeapRegion::ParEvacFailureClaimValue), "sanity"); 4374 4375 // Reset the claim values in the regions in the collection set. 4376 reset_cset_heap_region_claim_values(); 4377 4378 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity"); 4379 4380 // Now restore saved marks, if any. 4381 assert(_objs_with_preserved_marks.size() == 4382 _preserved_marks_of_objs.size(), "Both or none."); 4383 while (!_objs_with_preserved_marks.is_empty()) { 4384 oop obj = _objs_with_preserved_marks.pop(); 4385 markOop m = _preserved_marks_of_objs.pop(); 4386 obj->set_mark(m); 4387 } 4388 _objs_with_preserved_marks.clear(true); 4389 _preserved_marks_of_objs.clear(true); 4390 4391 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0); 4392 } 4393 4394 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) { 4395 _evac_failure_scan_stack->push(obj); 4396 } 4397 4398 void G1CollectedHeap::drain_evac_failure_scan_stack() { 4399 assert(_evac_failure_scan_stack != NULL, "precondition"); 4400 4401 while (_evac_failure_scan_stack->length() > 0) { 4402 oop obj = _evac_failure_scan_stack->pop(); 4403 _evac_failure_closure->set_region(heap_region_containing(obj)); 4404 obj->oop_iterate_backwards(_evac_failure_closure); 4405 } 4406 } 4407 4408 oop 4409 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state, 4410 oop old) { 4411 assert(obj_in_cs(old), 4412 err_msg("obj: "PTR_FORMAT" should still be in the CSet", 4413 (HeapWord*) old)); 4414 markOop m = old->mark(); 4415 oop forward_ptr = old->forward_to_atomic(old); 4416 if (forward_ptr == NULL) { 4417 // Forward-to-self succeeded. 4418 assert(_par_scan_state != NULL, "par scan state"); 4419 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure(); 4420 uint queue_num = _par_scan_state->queue_num(); 4421 4422 _evacuation_failed = true; 4423 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size()); 4424 if (_evac_failure_closure != cl) { 4425 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag); 4426 assert(!_drain_in_progress, 4427 "Should only be true while someone holds the lock."); 4428 // Set the global evac-failure closure to the current thread's. 4429 assert(_evac_failure_closure == NULL, "Or locking has failed."); 4430 set_evac_failure_closure(cl); 4431 // Now do the common part. 4432 handle_evacuation_failure_common(old, m); 4433 // Reset to NULL. 4434 set_evac_failure_closure(NULL); 4435 } else { 4436 // The lock is already held, and this is recursive. 4437 assert(_drain_in_progress, "This should only be the recursive case."); 4438 handle_evacuation_failure_common(old, m); 4439 } 4440 return old; 4441 } else { 4442 // Forward-to-self failed. Either someone else managed to allocate 4443 // space for this object (old != forward_ptr) or they beat us in 4444 // self-forwarding it (old == forward_ptr). 4445 assert(old == forward_ptr || !obj_in_cs(forward_ptr), 4446 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" " 4447 "should not be in the CSet", 4448 (HeapWord*) old, (HeapWord*) forward_ptr)); 4449 return forward_ptr; 4450 } 4451 } 4452 4453 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) { 4454 preserve_mark_if_necessary(old, m); 4455 4456 HeapRegion* r = heap_region_containing(old); 4457 if (!r->evacuation_failed()) { 4458 r->set_evacuation_failed(true); 4459 _hr_printer.evac_failure(r); 4460 } 4461 4462 push_on_evac_failure_scan_stack(old); 4463 4464 if (!_drain_in_progress) { 4465 // prevent recursion in copy_to_survivor_space() 4466 _drain_in_progress = true; 4467 drain_evac_failure_scan_stack(); 4468 _drain_in_progress = false; 4469 } 4470 } 4471 4472 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) { 4473 assert(evacuation_failed(), "Oversaving!"); 4474 // We want to call the "for_promotion_failure" version only in the 4475 // case of a promotion failure. 4476 if (m->must_be_preserved_for_promotion_failure(obj)) { 4477 _objs_with_preserved_marks.push(obj); 4478 _preserved_marks_of_objs.push(m); 4479 } 4480 } 4481 4482 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose, 4483 size_t word_size) { 4484 if (purpose == GCAllocForSurvived) { 4485 HeapWord* result = survivor_attempt_allocation(word_size); 4486 if (result != NULL) { 4487 return result; 4488 } else { 4489 // Let's try to allocate in the old gen in case we can fit the 4490 // object there. 4491 return old_attempt_allocation(word_size); 4492 } 4493 } else { 4494 assert(purpose == GCAllocForTenured, "sanity"); 4495 HeapWord* result = old_attempt_allocation(word_size); 4496 if (result != NULL) { 4497 return result; 4498 } else { 4499 // Let's try to allocate in the survivors in case we can fit the 4500 // object there. 4501 return survivor_attempt_allocation(word_size); 4502 } 4503 } 4504 4505 ShouldNotReachHere(); 4506 // Trying to keep some compilers happy. 4507 return NULL; 4508 } 4509 4510 G1ParGCAllocBuffer::G1ParGCAllocBuffer(size_t gclab_word_size) : 4511 ParGCAllocBuffer(gclab_word_size), _retired(true) { } 4512 4513 void G1ParCopyHelper::mark_object(oop obj) { 4514 assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet"); 4515 4516 // We know that the object is not moving so it's safe to read its size. 4517 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id); 4518 } 4519 4520 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) { 4521 assert(from_obj->is_forwarded(), "from obj should be forwarded"); 4522 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee"); 4523 assert(from_obj != to_obj, "should not be self-forwarded"); 4524 4525 assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet"); 4526 assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet"); 4527 4528 // The object might be in the process of being copied by another 4529 // worker so we cannot trust that its to-space image is 4530 // well-formed. So we have to read its size from its from-space 4531 // image which we know should not be changing. 4532 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id); 4533 } 4534 4535 template <class T> 4536 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) { 4537 if (_g1->heap_region_containing_raw(new_obj)->is_young()) { 4538 _scanned_klass->record_modified_oops(); 4539 } 4540 } 4541 4542 template <G1Barrier barrier, G1Mark do_mark_object> 4543 template <class T> 4544 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) { 4545 T heap_oop = oopDesc::load_heap_oop(p); 4546 4547 if (oopDesc::is_null(heap_oop)) { 4548 return; 4549 } 4550 4551 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 4552 4553 assert(_worker_id == _par_scan_state->queue_num(), "sanity"); 4554 4555 G1CollectedHeap::in_cset_state_t state = _g1->in_cset_state(obj); 4556 4557 if (state == G1CollectedHeap::InCSet) { 4558 oop forwardee; 4559 if (obj->is_forwarded()) { 4560 forwardee = obj->forwardee(); 4561 } else { 4562 forwardee = _par_scan_state->copy_to_survivor_space(obj); 4563 } 4564 assert(forwardee != NULL, "forwardee should not be NULL"); 4565 oopDesc::encode_store_heap_oop(p, forwardee); 4566 if (do_mark_object != G1MarkNone && forwardee != obj) { 4567 // If the object is self-forwarded we don't need to explicitly 4568 // mark it, the evacuation failure protocol will do so. 4569 mark_forwarded_object(obj, forwardee); 4570 } 4571 4572 if (barrier == G1BarrierKlass) { 4573 do_klass_barrier(p, forwardee); 4574 } 4575 } else { 4576 if (state == G1CollectedHeap::IsHumongous) { 4577 _g1->set_humongous_is_live(obj); 4578 } 4579 // The object is not in collection set. If we're a root scanning 4580 // closure during an initial mark pause then attempt to mark the object. 4581 if (do_mark_object == G1MarkFromRoot) { 4582 mark_object(obj); 4583 } 4584 } 4585 4586 if (barrier == G1BarrierEvac) { 4587 _par_scan_state->update_rs(_from, p, _worker_id); 4588 } 4589 } 4590 4591 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(oop* p); 4592 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(narrowOop* p); 4593 4594 class G1ParEvacuateFollowersClosure : public VoidClosure { 4595 protected: 4596 G1CollectedHeap* _g1h; 4597 G1ParScanThreadState* _par_scan_state; 4598 RefToScanQueueSet* _queues; 4599 ParallelTaskTerminator* _terminator; 4600 4601 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 4602 RefToScanQueueSet* queues() { return _queues; } 4603 ParallelTaskTerminator* terminator() { return _terminator; } 4604 4605 public: 4606 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h, 4607 G1ParScanThreadState* par_scan_state, 4608 RefToScanQueueSet* queues, 4609 ParallelTaskTerminator* terminator) 4610 : _g1h(g1h), _par_scan_state(par_scan_state), 4611 _queues(queues), _terminator(terminator) {} 4612 4613 void do_void(); 4614 4615 private: 4616 inline bool offer_termination(); 4617 }; 4618 4619 bool G1ParEvacuateFollowersClosure::offer_termination() { 4620 G1ParScanThreadState* const pss = par_scan_state(); 4621 pss->start_term_time(); 4622 const bool res = terminator()->offer_termination(); 4623 pss->end_term_time(); 4624 return res; 4625 } 4626 4627 void G1ParEvacuateFollowersClosure::do_void() { 4628 G1ParScanThreadState* const pss = par_scan_state(); 4629 pss->trim_queue(); 4630 do { 4631 pss->steal_and_trim_queue(queues()); 4632 } while (!offer_termination()); 4633 } 4634 4635 class G1KlassScanClosure : public KlassClosure { 4636 G1ParCopyHelper* _closure; 4637 bool _process_only_dirty; 4638 int _count; 4639 public: 4640 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty) 4641 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {} 4642 void do_klass(Klass* klass) { 4643 // If the klass has not been dirtied we know that there's 4644 // no references into the young gen and we can skip it. 4645 if (!_process_only_dirty || klass->has_modified_oops()) { 4646 // Clean the klass since we're going to scavenge all the metadata. 4647 klass->clear_modified_oops(); 4648 4649 // Tell the closure that this klass is the Klass to scavenge 4650 // and is the one to dirty if oops are left pointing into the young gen. 4651 _closure->set_scanned_klass(klass); 4652 4653 klass->oops_do(_closure); 4654 4655 _closure->set_scanned_klass(NULL); 4656 } 4657 _count++; 4658 } 4659 }; 4660 4661 class G1ParTask : public AbstractGangTask { 4662 protected: 4663 G1CollectedHeap* _g1h; 4664 RefToScanQueueSet *_queues; 4665 ParallelTaskTerminator _terminator; 4666 uint _n_workers; 4667 4668 Mutex _stats_lock; 4669 Mutex* stats_lock() { return &_stats_lock; } 4670 4671 public: 4672 G1ParTask(G1CollectedHeap* g1h, RefToScanQueueSet *task_queues) 4673 : AbstractGangTask("G1 collection"), 4674 _g1h(g1h), 4675 _queues(task_queues), 4676 _terminator(0, _queues), 4677 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true) 4678 {} 4679 4680 RefToScanQueueSet* queues() { return _queues; } 4681 4682 RefToScanQueue *work_queue(int i) { 4683 return queues()->queue(i); 4684 } 4685 4686 ParallelTaskTerminator* terminator() { return &_terminator; } 4687 4688 virtual void set_for_termination(int active_workers) { 4689 // This task calls set_n_termination() in par_non_clean_card_iterate_work() 4690 // in the young space (_par_seq_tasks) in the G1 heap 4691 // for SequentialSubTasksDone. 4692 // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap 4693 // both of which need setting by set_n_termination(). 4694 _g1h->SharedHeap::set_n_termination(active_workers); 4695 _g1h->set_n_termination(active_workers); 4696 terminator()->reset_for_reuse(active_workers); 4697 _n_workers = active_workers; 4698 } 4699 4700 // Helps out with CLD processing. 4701 // 4702 // During InitialMark we need to: 4703 // 1) Scavenge all CLDs for the young GC. 4704 // 2) Mark all objects directly reachable from strong CLDs. 4705 template <G1Mark do_mark_object> 4706 class G1CLDClosure : public CLDClosure { 4707 G1ParCopyClosure<G1BarrierNone, do_mark_object>* _oop_closure; 4708 G1ParCopyClosure<G1BarrierKlass, do_mark_object> _oop_in_klass_closure; 4709 G1KlassScanClosure _klass_in_cld_closure; 4710 bool _claim; 4711 4712 public: 4713 G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure, 4714 bool only_young, bool claim) 4715 : _oop_closure(oop_closure), 4716 _oop_in_klass_closure(oop_closure->g1(), 4717 oop_closure->pss(), 4718 oop_closure->rp()), 4719 _klass_in_cld_closure(&_oop_in_klass_closure, only_young), 4720 _claim(claim) { 4721 4722 } 4723 4724 void do_cld(ClassLoaderData* cld) { 4725 cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim); 4726 } 4727 }; 4728 4729 class G1CodeBlobClosure: public CodeBlobClosure { 4730 OopClosure* _f; 4731 4732 public: 4733 G1CodeBlobClosure(OopClosure* f) : _f(f) {} 4734 void do_code_blob(CodeBlob* blob) { 4735 nmethod* that = blob->as_nmethod_or_null(); 4736 if (that != NULL) { 4737 if (!that->test_set_oops_do_mark()) { 4738 that->oops_do(_f); 4739 that->fix_oop_relocations(); 4740 } 4741 } 4742 } 4743 }; 4744 4745 void work(uint worker_id) { 4746 if (worker_id >= _n_workers) return; // no work needed this round 4747 4748 double start_time_ms = os::elapsedTime() * 1000.0; 4749 _g1h->g1_policy()->phase_times()->record_gc_worker_start_time(worker_id, start_time_ms); 4750 4751 { 4752 ResourceMark rm; 4753 HandleMark hm; 4754 4755 ReferenceProcessor* rp = _g1h->ref_processor_stw(); 4756 4757 G1ParScanThreadState pss(_g1h, worker_id, rp); 4758 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp); 4759 4760 pss.set_evac_failure_closure(&evac_failure_cl); 4761 4762 bool only_young = _g1h->g1_policy()->gcs_are_young(); 4763 4764 // Non-IM young GC. 4765 G1ParCopyClosure<G1BarrierNone, G1MarkNone> scan_only_root_cl(_g1h, &pss, rp); 4766 G1CLDClosure<G1MarkNone> scan_only_cld_cl(&scan_only_root_cl, 4767 only_young, // Only process dirty klasses. 4768 false); // No need to claim CLDs. 4769 // IM young GC. 4770 // Strong roots closures. 4771 G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot> scan_mark_root_cl(_g1h, &pss, rp); 4772 G1CLDClosure<G1MarkFromRoot> scan_mark_cld_cl(&scan_mark_root_cl, 4773 false, // Process all klasses. 4774 true); // Need to claim CLDs. 4775 // Weak roots closures. 4776 G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, &pss, rp); 4777 G1CLDClosure<G1MarkPromotedFromRoot> scan_mark_weak_cld_cl(&scan_mark_weak_root_cl, 4778 false, // Process all klasses. 4779 true); // Need to claim CLDs. 4780 4781 G1CodeBlobClosure scan_only_code_cl(&scan_only_root_cl); 4782 G1CodeBlobClosure scan_mark_code_cl(&scan_mark_root_cl); 4783 // IM Weak code roots are handled later. 4784 4785 OopClosure* strong_root_cl; 4786 OopClosure* weak_root_cl; 4787 CLDClosure* strong_cld_cl; 4788 CLDClosure* weak_cld_cl; 4789 CodeBlobClosure* strong_code_cl; 4790 4791 if (_g1h->g1_policy()->during_initial_mark_pause()) { 4792 // We also need to mark copied objects. 4793 strong_root_cl = &scan_mark_root_cl; 4794 strong_cld_cl = &scan_mark_cld_cl; 4795 strong_code_cl = &scan_mark_code_cl; 4796 if (ClassUnloadingWithConcurrentMark) { 4797 weak_root_cl = &scan_mark_weak_root_cl; 4798 weak_cld_cl = &scan_mark_weak_cld_cl; 4799 } else { 4800 weak_root_cl = &scan_mark_root_cl; 4801 weak_cld_cl = &scan_mark_cld_cl; 4802 } 4803 } else { 4804 strong_root_cl = &scan_only_root_cl; 4805 weak_root_cl = &scan_only_root_cl; 4806 strong_cld_cl = &scan_only_cld_cl; 4807 weak_cld_cl = &scan_only_cld_cl; 4808 strong_code_cl = &scan_only_code_cl; 4809 } 4810 4811 4812 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss); 4813 4814 pss.start_strong_roots(); 4815 _g1h->g1_process_roots(strong_root_cl, 4816 weak_root_cl, 4817 &push_heap_rs_cl, 4818 strong_cld_cl, 4819 weak_cld_cl, 4820 strong_code_cl, 4821 worker_id); 4822 4823 pss.end_strong_roots(); 4824 4825 { 4826 double start = os::elapsedTime(); 4827 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator); 4828 evac.do_void(); 4829 double elapsed_ms = (os::elapsedTime()-start)*1000.0; 4830 double term_ms = pss.term_time()*1000.0; 4831 _g1h->g1_policy()->phase_times()->add_obj_copy_time(worker_id, elapsed_ms-term_ms); 4832 _g1h->g1_policy()->phase_times()->record_termination(worker_id, term_ms, pss.term_attempts()); 4833 } 4834 _g1h->g1_policy()->record_thread_age_table(pss.age_table()); 4835 _g1h->update_surviving_young_words(pss.surviving_young_words()+1); 4836 4837 if (ParallelGCVerbose) { 4838 MutexLocker x(stats_lock()); 4839 pss.print_termination_stats(worker_id); 4840 } 4841 4842 assert(pss.queue_is_empty(), "should be empty"); 4843 4844 // Close the inner scope so that the ResourceMark and HandleMark 4845 // destructors are executed here and are included as part of the 4846 // "GC Worker Time". 4847 } 4848 4849 double end_time_ms = os::elapsedTime() * 1000.0; 4850 _g1h->g1_policy()->phase_times()->record_gc_worker_end_time(worker_id, end_time_ms); 4851 } 4852 }; 4853 4854 // *** Common G1 Evacuation Stuff 4855 4856 // This method is run in a GC worker. 4857 4858 void 4859 G1CollectedHeap:: 4860 g1_process_roots(OopClosure* scan_non_heap_roots, 4861 OopClosure* scan_non_heap_weak_roots, 4862 OopsInHeapRegionClosure* scan_rs, 4863 CLDClosure* scan_strong_clds, 4864 CLDClosure* scan_weak_clds, 4865 CodeBlobClosure* scan_strong_code, 4866 uint worker_i) { 4867 4868 // First scan the shared roots. 4869 double ext_roots_start = os::elapsedTime(); 4870 double closure_app_time_sec = 0.0; 4871 4872 bool during_im = _g1h->g1_policy()->during_initial_mark_pause(); 4873 bool trace_metadata = during_im && ClassUnloadingWithConcurrentMark; 4874 4875 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots); 4876 BufferingOopClosure buf_scan_non_heap_weak_roots(scan_non_heap_weak_roots); 4877 4878 process_roots(false, // no scoping; this is parallel code 4879 SharedHeap::SO_None, 4880 &buf_scan_non_heap_roots, 4881 &buf_scan_non_heap_weak_roots, 4882 scan_strong_clds, 4883 // Unloading Initial Marks handle the weak CLDs separately. 4884 (trace_metadata ? NULL : scan_weak_clds), 4885 scan_strong_code); 4886 4887 // Now the CM ref_processor roots. 4888 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) { 4889 // We need to treat the discovered reference lists of the 4890 // concurrent mark ref processor as roots and keep entries 4891 // (which are added by the marking threads) on them live 4892 // until they can be processed at the end of marking. 4893 ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots); 4894 } 4895 4896 if (trace_metadata) { 4897 // Barrier to make sure all workers passed 4898 // the strong CLD and strong nmethods phases. 4899 active_strong_roots_scope()->wait_until_all_workers_done_with_threads(n_par_threads()); 4900 4901 // Now take the complement of the strong CLDs. 4902 ClassLoaderDataGraph::roots_cld_do(NULL, scan_weak_clds); 4903 } 4904 4905 // Finish up any enqueued closure apps (attributed as object copy time). 4906 buf_scan_non_heap_roots.done(); 4907 buf_scan_non_heap_weak_roots.done(); 4908 4909 double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds() 4910 + buf_scan_non_heap_weak_roots.closure_app_seconds(); 4911 4912 g1_policy()->phase_times()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0); 4913 4914 double ext_root_time_ms = 4915 ((os::elapsedTime() - ext_roots_start) - obj_copy_time_sec) * 1000.0; 4916 4917 g1_policy()->phase_times()->record_ext_root_scan_time(worker_i, ext_root_time_ms); 4918 4919 // During conc marking we have to filter the per-thread SATB buffers 4920 // to make sure we remove any oops into the CSet (which will show up 4921 // as implicitly live). 4922 double satb_filtering_ms = 0.0; 4923 if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers)) { 4924 if (mark_in_progress()) { 4925 double satb_filter_start = os::elapsedTime(); 4926 4927 JavaThread::satb_mark_queue_set().filter_thread_buffers(); 4928 4929 satb_filtering_ms = (os::elapsedTime() - satb_filter_start) * 1000.0; 4930 } 4931 } 4932 g1_policy()->phase_times()->record_satb_filtering_time(worker_i, satb_filtering_ms); 4933 4934 // Now scan the complement of the collection set. 4935 MarkingCodeBlobClosure scavenge_cs_nmethods(scan_non_heap_weak_roots, CodeBlobToOopClosure::FixRelocations); 4936 4937 g1_rem_set()->oops_into_collection_set_do(scan_rs, &scavenge_cs_nmethods, worker_i); 4938 4939 _process_strong_tasks->all_tasks_completed(); 4940 } 4941 4942 class G1StringSymbolTableUnlinkTask : public AbstractGangTask { 4943 private: 4944 BoolObjectClosure* _is_alive; 4945 int _initial_string_table_size; 4946 int _initial_symbol_table_size; 4947 4948 bool _process_strings; 4949 int _strings_processed; 4950 int _strings_removed; 4951 4952 bool _process_symbols; 4953 int _symbols_processed; 4954 int _symbols_removed; 4955 4956 bool _do_in_parallel; 4957 public: 4958 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) : 4959 AbstractGangTask("String/Symbol Unlinking"), 4960 _is_alive(is_alive), 4961 _do_in_parallel(G1CollectedHeap::use_parallel_gc_threads()), 4962 _process_strings(process_strings), _strings_processed(0), _strings_removed(0), 4963 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) { 4964 4965 _initial_string_table_size = StringTable::the_table()->table_size(); 4966 _initial_symbol_table_size = SymbolTable::the_table()->table_size(); 4967 if (process_strings) { 4968 StringTable::clear_parallel_claimed_index(); 4969 } 4970 if (process_symbols) { 4971 SymbolTable::clear_parallel_claimed_index(); 4972 } 4973 } 4974 4975 ~G1StringSymbolTableUnlinkTask() { 4976 guarantee(!_process_strings || !_do_in_parallel || StringTable::parallel_claimed_index() >= _initial_string_table_size, 4977 err_msg("claim value %d after unlink less than initial string table size %d", 4978 StringTable::parallel_claimed_index(), _initial_string_table_size)); 4979 guarantee(!_process_symbols || !_do_in_parallel || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size, 4980 err_msg("claim value %d after unlink less than initial symbol table size %d", 4981 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size)); 4982 4983 if (G1TraceStringSymbolTableScrubbing) { 4984 gclog_or_tty->print_cr("Cleaned string and symbol table, " 4985 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, " 4986 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed", 4987 strings_processed(), strings_removed(), 4988 symbols_processed(), symbols_removed()); 4989 } 4990 } 4991 4992 void work(uint worker_id) { 4993 if (_do_in_parallel) { 4994 int strings_processed = 0; 4995 int strings_removed = 0; 4996 int symbols_processed = 0; 4997 int symbols_removed = 0; 4998 if (_process_strings) { 4999 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed); 5000 Atomic::add(strings_processed, &_strings_processed); 5001 Atomic::add(strings_removed, &_strings_removed); 5002 } 5003 if (_process_symbols) { 5004 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed); 5005 Atomic::add(symbols_processed, &_symbols_processed); 5006 Atomic::add(symbols_removed, &_symbols_removed); 5007 } 5008 } else { 5009 if (_process_strings) { 5010 StringTable::unlink(_is_alive, &_strings_processed, &_strings_removed); 5011 } 5012 if (_process_symbols) { 5013 SymbolTable::unlink(&_symbols_processed, &_symbols_removed); 5014 } 5015 } 5016 } 5017 5018 size_t strings_processed() const { return (size_t)_strings_processed; } 5019 size_t strings_removed() const { return (size_t)_strings_removed; } 5020 5021 size_t symbols_processed() const { return (size_t)_symbols_processed; } 5022 size_t symbols_removed() const { return (size_t)_symbols_removed; } 5023 }; 5024 5025 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC { 5026 private: 5027 static Monitor* _lock; 5028 5029 BoolObjectClosure* const _is_alive; 5030 const bool _unloading_occurred; 5031 const uint _num_workers; 5032 5033 // Variables used to claim nmethods. 5034 nmethod* _first_nmethod; 5035 volatile nmethod* _claimed_nmethod; 5036 5037 // The list of nmethods that need to be processed by the second pass. 5038 volatile nmethod* _postponed_list; 5039 volatile uint _num_entered_barrier; 5040 5041 public: 5042 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) : 5043 _is_alive(is_alive), 5044 _unloading_occurred(unloading_occurred), 5045 _num_workers(num_workers), 5046 _first_nmethod(NULL), 5047 _claimed_nmethod(NULL), 5048 _postponed_list(NULL), 5049 _num_entered_barrier(0) 5050 { 5051 nmethod::increase_unloading_clock(); 5052 _first_nmethod = CodeCache::alive_nmethod(CodeCache::first()); 5053 _claimed_nmethod = (volatile nmethod*)_first_nmethod; 5054 } 5055 5056 ~G1CodeCacheUnloadingTask() { 5057 CodeCache::verify_clean_inline_caches(); 5058 5059 CodeCache::set_needs_cache_clean(false); 5060 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be"); 5061 5062 CodeCache::verify_icholder_relocations(); 5063 } 5064 5065 private: 5066 void add_to_postponed_list(nmethod* nm) { 5067 nmethod* old; 5068 do { 5069 old = (nmethod*)_postponed_list; 5070 nm->set_unloading_next(old); 5071 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old); 5072 } 5073 5074 void clean_nmethod(nmethod* nm) { 5075 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred); 5076 5077 if (postponed) { 5078 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet. 5079 add_to_postponed_list(nm); 5080 } 5081 5082 // Mark that this thread has been cleaned/unloaded. 5083 // After this call, it will be safe to ask if this nmethod was unloaded or not. 5084 nm->set_unloading_clock(nmethod::global_unloading_clock()); 5085 } 5086 5087 void clean_nmethod_postponed(nmethod* nm) { 5088 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred); 5089 } 5090 5091 static const int MaxClaimNmethods = 16; 5092 5093 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) { 5094 nmethod* first; 5095 nmethod* last; 5096 5097 do { 5098 *num_claimed_nmethods = 0; 5099 5100 first = last = (nmethod*)_claimed_nmethod; 5101 5102 if (first != NULL) { 5103 for (int i = 0; i < MaxClaimNmethods; i++) { 5104 last = CodeCache::alive_nmethod(CodeCache::next(last)); 5105 5106 if (last == NULL) { 5107 break; 5108 } 5109 5110 claimed_nmethods[i] = last; 5111 (*num_claimed_nmethods)++; 5112 } 5113 } 5114 5115 } while ((nmethod*)Atomic::cmpxchg_ptr(last, &_claimed_nmethod, first) != first); 5116 } 5117 5118 nmethod* claim_postponed_nmethod() { 5119 nmethod* claim; 5120 nmethod* next; 5121 5122 do { 5123 claim = (nmethod*)_postponed_list; 5124 if (claim == NULL) { 5125 return NULL; 5126 } 5127 5128 next = claim->unloading_next(); 5129 5130 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim); 5131 5132 return claim; 5133 } 5134 5135 public: 5136 // Mark that we're done with the first pass of nmethod cleaning. 5137 void barrier_mark(uint worker_id) { 5138 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 5139 _num_entered_barrier++; 5140 if (_num_entered_barrier == _num_workers) { 5141 ml.notify_all(); 5142 } 5143 } 5144 5145 // See if we have to wait for the other workers to 5146 // finish their first-pass nmethod cleaning work. 5147 void barrier_wait(uint worker_id) { 5148 if (_num_entered_barrier < _num_workers) { 5149 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 5150 while (_num_entered_barrier < _num_workers) { 5151 ml.wait(Mutex::_no_safepoint_check_flag, 0, false); 5152 } 5153 } 5154 } 5155 5156 // Cleaning and unloading of nmethods. Some work has to be postponed 5157 // to the second pass, when we know which nmethods survive. 5158 void work_first_pass(uint worker_id) { 5159 // The first nmethods is claimed by the first worker. 5160 if (worker_id == 0 && _first_nmethod != NULL) { 5161 clean_nmethod(_first_nmethod); 5162 _first_nmethod = NULL; 5163 } 5164 5165 int num_claimed_nmethods; 5166 nmethod* claimed_nmethods[MaxClaimNmethods]; 5167 5168 while (true) { 5169 claim_nmethods(claimed_nmethods, &num_claimed_nmethods); 5170 5171 if (num_claimed_nmethods == 0) { 5172 break; 5173 } 5174 5175 for (int i = 0; i < num_claimed_nmethods; i++) { 5176 clean_nmethod(claimed_nmethods[i]); 5177 } 5178 } 5179 } 5180 5181 void work_second_pass(uint worker_id) { 5182 nmethod* nm; 5183 // Take care of postponed nmethods. 5184 while ((nm = claim_postponed_nmethod()) != NULL) { 5185 clean_nmethod_postponed(nm); 5186 } 5187 } 5188 }; 5189 5190 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock"); 5191 5192 class G1KlassCleaningTask : public StackObj { 5193 BoolObjectClosure* _is_alive; 5194 volatile jint _clean_klass_tree_claimed; 5195 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator; 5196 5197 public: 5198 G1KlassCleaningTask(BoolObjectClosure* is_alive) : 5199 _is_alive(is_alive), 5200 _clean_klass_tree_claimed(0), 5201 _klass_iterator() { 5202 } 5203 5204 private: 5205 bool claim_clean_klass_tree_task() { 5206 if (_clean_klass_tree_claimed) { 5207 return false; 5208 } 5209 5210 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0; 5211 } 5212 5213 InstanceKlass* claim_next_klass() { 5214 Klass* klass; 5215 do { 5216 klass =_klass_iterator.next_klass(); 5217 } while (klass != NULL && !klass->oop_is_instance()); 5218 5219 return (InstanceKlass*)klass; 5220 } 5221 5222 public: 5223 5224 void clean_klass(InstanceKlass* ik) { 5225 ik->clean_implementors_list(_is_alive); 5226 ik->clean_method_data(_is_alive); 5227 5228 // G1 specific cleanup work that has 5229 // been moved here to be done in parallel. 5230 ik->clean_dependent_nmethods(); 5231 } 5232 5233 void work() { 5234 ResourceMark rm; 5235 5236 // One worker will clean the subklass/sibling klass tree. 5237 if (claim_clean_klass_tree_task()) { 5238 Klass::clean_subklass_tree(_is_alive); 5239 } 5240 5241 // All workers will help cleaning the classes, 5242 InstanceKlass* klass; 5243 while ((klass = claim_next_klass()) != NULL) { 5244 clean_klass(klass); 5245 } 5246 } 5247 }; 5248 5249 // To minimize the remark pause times, the tasks below are done in parallel. 5250 class G1ParallelCleaningTask : public AbstractGangTask { 5251 private: 5252 G1StringSymbolTableUnlinkTask _string_symbol_task; 5253 G1CodeCacheUnloadingTask _code_cache_task; 5254 G1KlassCleaningTask _klass_cleaning_task; 5255 5256 public: 5257 // The constructor is run in the VMThread. 5258 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) : 5259 AbstractGangTask("Parallel Cleaning"), 5260 _string_symbol_task(is_alive, process_strings, process_symbols), 5261 _code_cache_task(num_workers, is_alive, unloading_occurred), 5262 _klass_cleaning_task(is_alive) { 5263 } 5264 5265 // The parallel work done by all worker threads. 5266 void work(uint worker_id) { 5267 // Do first pass of code cache cleaning. 5268 _code_cache_task.work_first_pass(worker_id); 5269 5270 // Let the threads mark that the first pass is done. 5271 _code_cache_task.barrier_mark(worker_id); 5272 5273 // Clean the Strings and Symbols. 5274 _string_symbol_task.work(worker_id); 5275 5276 // Wait for all workers to finish the first code cache cleaning pass. 5277 _code_cache_task.barrier_wait(worker_id); 5278 5279 // Do the second code cache cleaning work, which realize on 5280 // the liveness information gathered during the first pass. 5281 _code_cache_task.work_second_pass(worker_id); 5282 5283 // Clean all klasses that were not unloaded. 5284 _klass_cleaning_task.work(); 5285 } 5286 }; 5287 5288 5289 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive, 5290 bool process_strings, 5291 bool process_symbols, 5292 bool class_unloading_occurred) { 5293 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ? 5294 workers()->active_workers() : 1); 5295 5296 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, 5297 n_workers, class_unloading_occurred); 5298 if (G1CollectedHeap::use_parallel_gc_threads()) { 5299 set_par_threads(n_workers); 5300 workers()->run_task(&g1_unlink_task); 5301 set_par_threads(0); 5302 } else { 5303 g1_unlink_task.work(0); 5304 } 5305 } 5306 5307 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive, 5308 bool process_strings, bool process_symbols) { 5309 { 5310 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ? 5311 _g1h->workers()->active_workers() : 1); 5312 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols); 5313 if (G1CollectedHeap::use_parallel_gc_threads()) { 5314 set_par_threads(n_workers); 5315 workers()->run_task(&g1_unlink_task); 5316 set_par_threads(0); 5317 } else { 5318 g1_unlink_task.work(0); 5319 } 5320 } 5321 5322 if (G1StringDedup::is_enabled()) { 5323 G1StringDedup::unlink(is_alive); 5324 } 5325 } 5326 5327 class G1RedirtyLoggedCardsTask : public AbstractGangTask { 5328 private: 5329 DirtyCardQueueSet* _queue; 5330 public: 5331 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { } 5332 5333 virtual void work(uint worker_id) { 5334 double start_time = os::elapsedTime(); 5335 5336 RedirtyLoggedCardTableEntryClosure cl; 5337 if (G1CollectedHeap::heap()->use_parallel_gc_threads()) { 5338 _queue->par_apply_closure_to_all_completed_buffers(&cl); 5339 } else { 5340 _queue->apply_closure_to_all_completed_buffers(&cl); 5341 } 5342 5343 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times(); 5344 timer->record_redirty_logged_cards_time_ms(worker_id, (os::elapsedTime() - start_time) * 1000.0); 5345 timer->record_redirty_logged_cards_processed_cards(worker_id, cl.num_processed()); 5346 } 5347 }; 5348 5349 void G1CollectedHeap::redirty_logged_cards() { 5350 guarantee(G1DeferredRSUpdate, "Must only be called when using deferred RS updates."); 5351 double redirty_logged_cards_start = os::elapsedTime(); 5352 5353 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ? 5354 _g1h->workers()->active_workers() : 1); 5355 5356 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set()); 5357 dirty_card_queue_set().reset_for_par_iteration(); 5358 if (use_parallel_gc_threads()) { 5359 set_par_threads(n_workers); 5360 workers()->run_task(&redirty_task); 5361 set_par_threads(0); 5362 } else { 5363 redirty_task.work(0); 5364 } 5365 5366 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set(); 5367 dcq.merge_bufferlists(&dirty_card_queue_set()); 5368 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed"); 5369 5370 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0); 5371 } 5372 5373 // Weak Reference Processing support 5374 5375 // An always "is_alive" closure that is used to preserve referents. 5376 // If the object is non-null then it's alive. Used in the preservation 5377 // of referent objects that are pointed to by reference objects 5378 // discovered by the CM ref processor. 5379 class G1AlwaysAliveClosure: public BoolObjectClosure { 5380 G1CollectedHeap* _g1; 5381 public: 5382 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 5383 bool do_object_b(oop p) { 5384 if (p != NULL) { 5385 return true; 5386 } 5387 return false; 5388 } 5389 }; 5390 5391 bool G1STWIsAliveClosure::do_object_b(oop p) { 5392 // An object is reachable if it is outside the collection set, 5393 // or is inside and copied. 5394 return !_g1->obj_in_cs(p) || p->is_forwarded(); 5395 } 5396 5397 // Non Copying Keep Alive closure 5398 class G1KeepAliveClosure: public OopClosure { 5399 G1CollectedHeap* _g1; 5400 public: 5401 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 5402 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } 5403 void do_oop(oop* p) { 5404 oop obj = *p; 5405 5406 G1CollectedHeap::in_cset_state_t cset_state = _g1->in_cset_state(obj); 5407 if (obj == NULL || cset_state == G1CollectedHeap::InNeither) { 5408 return; 5409 } 5410 if (cset_state == G1CollectedHeap::InCSet) { 5411 assert( obj->is_forwarded(), "invariant" ); 5412 *p = obj->forwardee(); 5413 } else { 5414 assert(!obj->is_forwarded(), "invariant" ); 5415 assert(cset_state == G1CollectedHeap::IsHumongous, 5416 err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state)); 5417 _g1->set_humongous_is_live(obj); 5418 } 5419 } 5420 }; 5421 5422 // Copying Keep Alive closure - can be called from both 5423 // serial and parallel code as long as different worker 5424 // threads utilize different G1ParScanThreadState instances 5425 // and different queues. 5426 5427 class G1CopyingKeepAliveClosure: public OopClosure { 5428 G1CollectedHeap* _g1h; 5429 OopClosure* _copy_non_heap_obj_cl; 5430 G1ParScanThreadState* _par_scan_state; 5431 5432 public: 5433 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, 5434 OopClosure* non_heap_obj_cl, 5435 G1ParScanThreadState* pss): 5436 _g1h(g1h), 5437 _copy_non_heap_obj_cl(non_heap_obj_cl), 5438 _par_scan_state(pss) 5439 {} 5440 5441 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 5442 virtual void do_oop( oop* p) { do_oop_work(p); } 5443 5444 template <class T> void do_oop_work(T* p) { 5445 oop obj = oopDesc::load_decode_heap_oop(p); 5446 5447 if (_g1h->is_in_cset_or_humongous(obj)) { 5448 // If the referent object has been forwarded (either copied 5449 // to a new location or to itself in the event of an 5450 // evacuation failure) then we need to update the reference 5451 // field and, if both reference and referent are in the G1 5452 // heap, update the RSet for the referent. 5453 // 5454 // If the referent has not been forwarded then we have to keep 5455 // it alive by policy. Therefore we have copy the referent. 5456 // 5457 // If the reference field is in the G1 heap then we can push 5458 // on the PSS queue. When the queue is drained (after each 5459 // phase of reference processing) the object and it's followers 5460 // will be copied, the reference field set to point to the 5461 // new location, and the RSet updated. Otherwise we need to 5462 // use the the non-heap or metadata closures directly to copy 5463 // the referent object and update the pointer, while avoiding 5464 // updating the RSet. 5465 5466 if (_g1h->is_in_g1_reserved(p)) { 5467 _par_scan_state->push_on_queue(p); 5468 } else { 5469 assert(!Metaspace::contains((const void*)p), 5470 err_msg("Unexpectedly found a pointer from metadata: " 5471 PTR_FORMAT, p)); 5472 _copy_non_heap_obj_cl->do_oop(p); 5473 } 5474 } 5475 } 5476 }; 5477 5478 // Serial drain queue closure. Called as the 'complete_gc' 5479 // closure for each discovered list in some of the 5480 // reference processing phases. 5481 5482 class G1STWDrainQueueClosure: public VoidClosure { 5483 protected: 5484 G1CollectedHeap* _g1h; 5485 G1ParScanThreadState* _par_scan_state; 5486 5487 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 5488 5489 public: 5490 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : 5491 _g1h(g1h), 5492 _par_scan_state(pss) 5493 { } 5494 5495 void do_void() { 5496 G1ParScanThreadState* const pss = par_scan_state(); 5497 pss->trim_queue(); 5498 } 5499 }; 5500 5501 // Parallel Reference Processing closures 5502 5503 // Implementation of AbstractRefProcTaskExecutor for parallel reference 5504 // processing during G1 evacuation pauses. 5505 5506 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 5507 private: 5508 G1CollectedHeap* _g1h; 5509 RefToScanQueueSet* _queues; 5510 FlexibleWorkGang* _workers; 5511 int _active_workers; 5512 5513 public: 5514 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, 5515 FlexibleWorkGang* workers, 5516 RefToScanQueueSet *task_queues, 5517 int n_workers) : 5518 _g1h(g1h), 5519 _queues(task_queues), 5520 _workers(workers), 5521 _active_workers(n_workers) 5522 { 5523 assert(n_workers > 0, "shouldn't call this otherwise"); 5524 } 5525 5526 // Executes the given task using concurrent marking worker threads. 5527 virtual void execute(ProcessTask& task); 5528 virtual void execute(EnqueueTask& task); 5529 }; 5530 5531 // Gang task for possibly parallel reference processing 5532 5533 class G1STWRefProcTaskProxy: public AbstractGangTask { 5534 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 5535 ProcessTask& _proc_task; 5536 G1CollectedHeap* _g1h; 5537 RefToScanQueueSet *_task_queues; 5538 ParallelTaskTerminator* _terminator; 5539 5540 public: 5541 G1STWRefProcTaskProxy(ProcessTask& proc_task, 5542 G1CollectedHeap* g1h, 5543 RefToScanQueueSet *task_queues, 5544 ParallelTaskTerminator* terminator) : 5545 AbstractGangTask("Process reference objects in parallel"), 5546 _proc_task(proc_task), 5547 _g1h(g1h), 5548 _task_queues(task_queues), 5549 _terminator(terminator) 5550 {} 5551 5552 virtual void work(uint worker_id) { 5553 // The reference processing task executed by a single worker. 5554 ResourceMark rm; 5555 HandleMark hm; 5556 5557 G1STWIsAliveClosure is_alive(_g1h); 5558 5559 G1ParScanThreadState pss(_g1h, worker_id, NULL); 5560 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL); 5561 5562 pss.set_evac_failure_closure(&evac_failure_cl); 5563 5564 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL); 5565 5566 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL); 5567 5568 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5569 5570 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5571 // We also need to mark copied objects. 5572 copy_non_heap_cl = ©_mark_non_heap_cl; 5573 } 5574 5575 // Keep alive closure. 5576 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss); 5577 5578 // Complete GC closure 5579 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator); 5580 5581 // Call the reference processing task's work routine. 5582 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); 5583 5584 // Note we cannot assert that the refs array is empty here as not all 5585 // of the processing tasks (specifically phase2 - pp2_work) execute 5586 // the complete_gc closure (which ordinarily would drain the queue) so 5587 // the queue may not be empty. 5588 } 5589 }; 5590 5591 // Driver routine for parallel reference processing. 5592 // Creates an instance of the ref processing gang 5593 // task and has the worker threads execute it. 5594 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) { 5595 assert(_workers != NULL, "Need parallel worker threads."); 5596 5597 ParallelTaskTerminator terminator(_active_workers, _queues); 5598 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator); 5599 5600 _g1h->set_par_threads(_active_workers); 5601 _workers->run_task(&proc_task_proxy); 5602 _g1h->set_par_threads(0); 5603 } 5604 5605 // Gang task for parallel reference enqueueing. 5606 5607 class G1STWRefEnqueueTaskProxy: public AbstractGangTask { 5608 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; 5609 EnqueueTask& _enq_task; 5610 5611 public: 5612 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) : 5613 AbstractGangTask("Enqueue reference objects in parallel"), 5614 _enq_task(enq_task) 5615 { } 5616 5617 virtual void work(uint worker_id) { 5618 _enq_task.work(worker_id); 5619 } 5620 }; 5621 5622 // Driver routine for parallel reference enqueueing. 5623 // Creates an instance of the ref enqueueing gang 5624 // task and has the worker threads execute it. 5625 5626 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) { 5627 assert(_workers != NULL, "Need parallel worker threads."); 5628 5629 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task); 5630 5631 _g1h->set_par_threads(_active_workers); 5632 _workers->run_task(&enq_task_proxy); 5633 _g1h->set_par_threads(0); 5634 } 5635 5636 // End of weak reference support closures 5637 5638 // Abstract task used to preserve (i.e. copy) any referent objects 5639 // that are in the collection set and are pointed to by reference 5640 // objects discovered by the CM ref processor. 5641 5642 class G1ParPreserveCMReferentsTask: public AbstractGangTask { 5643 protected: 5644 G1CollectedHeap* _g1h; 5645 RefToScanQueueSet *_queues; 5646 ParallelTaskTerminator _terminator; 5647 uint _n_workers; 5648 5649 public: 5650 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) : 5651 AbstractGangTask("ParPreserveCMReferents"), 5652 _g1h(g1h), 5653 _queues(task_queues), 5654 _terminator(workers, _queues), 5655 _n_workers(workers) 5656 { } 5657 5658 void work(uint worker_id) { 5659 ResourceMark rm; 5660 HandleMark hm; 5661 5662 G1ParScanThreadState pss(_g1h, worker_id, NULL); 5663 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL); 5664 5665 pss.set_evac_failure_closure(&evac_failure_cl); 5666 5667 assert(pss.queue_is_empty(), "both queue and overflow should be empty"); 5668 5669 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL); 5670 5671 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL); 5672 5673 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5674 5675 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5676 // We also need to mark copied objects. 5677 copy_non_heap_cl = ©_mark_non_heap_cl; 5678 } 5679 5680 // Is alive closure 5681 G1AlwaysAliveClosure always_alive(_g1h); 5682 5683 // Copying keep alive closure. Applied to referent objects that need 5684 // to be copied. 5685 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss); 5686 5687 ReferenceProcessor* rp = _g1h->ref_processor_cm(); 5688 5689 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q(); 5690 uint stride = MIN2(MAX2(_n_workers, 1U), limit); 5691 5692 // limit is set using max_num_q() - which was set using ParallelGCThreads. 5693 // So this must be true - but assert just in case someone decides to 5694 // change the worker ids. 5695 assert(0 <= worker_id && worker_id < limit, "sanity"); 5696 assert(!rp->discovery_is_atomic(), "check this code"); 5697 5698 // Select discovered lists [i, i+stride, i+2*stride,...,limit) 5699 for (uint idx = worker_id; idx < limit; idx += stride) { 5700 DiscoveredList& ref_list = rp->discovered_refs()[idx]; 5701 5702 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive); 5703 while (iter.has_next()) { 5704 // Since discovery is not atomic for the CM ref processor, we 5705 // can see some null referent objects. 5706 iter.load_ptrs(DEBUG_ONLY(true)); 5707 oop ref = iter.obj(); 5708 5709 // This will filter nulls. 5710 if (iter.is_referent_alive()) { 5711 iter.make_referent_alive(); 5712 } 5713 iter.move_to_next(); 5714 } 5715 } 5716 5717 // Drain the queue - which may cause stealing 5718 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator); 5719 drain_queue.do_void(); 5720 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure 5721 assert(pss.queue_is_empty(), "should be"); 5722 } 5723 }; 5724 5725 // Weak Reference processing during an evacuation pause (part 1). 5726 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) { 5727 double ref_proc_start = os::elapsedTime(); 5728 5729 ReferenceProcessor* rp = _ref_processor_stw; 5730 assert(rp->discovery_enabled(), "should have been enabled"); 5731 5732 // Any reference objects, in the collection set, that were 'discovered' 5733 // by the CM ref processor should have already been copied (either by 5734 // applying the external root copy closure to the discovered lists, or 5735 // by following an RSet entry). 5736 // 5737 // But some of the referents, that are in the collection set, that these 5738 // reference objects point to may not have been copied: the STW ref 5739 // processor would have seen that the reference object had already 5740 // been 'discovered' and would have skipped discovering the reference, 5741 // but would not have treated the reference object as a regular oop. 5742 // As a result the copy closure would not have been applied to the 5743 // referent object. 5744 // 5745 // We need to explicitly copy these referent objects - the references 5746 // will be processed at the end of remarking. 5747 // 5748 // We also need to do this copying before we process the reference 5749 // objects discovered by the STW ref processor in case one of these 5750 // referents points to another object which is also referenced by an 5751 // object discovered by the STW ref processor. 5752 5753 assert(!G1CollectedHeap::use_parallel_gc_threads() || 5754 no_of_gc_workers == workers()->active_workers(), 5755 "Need to reset active GC workers"); 5756 5757 set_par_threads(no_of_gc_workers); 5758 G1ParPreserveCMReferentsTask keep_cm_referents(this, 5759 no_of_gc_workers, 5760 _task_queues); 5761 5762 if (G1CollectedHeap::use_parallel_gc_threads()) { 5763 workers()->run_task(&keep_cm_referents); 5764 } else { 5765 keep_cm_referents.work(0); 5766 } 5767 5768 set_par_threads(0); 5769 5770 // Closure to test whether a referent is alive. 5771 G1STWIsAliveClosure is_alive(this); 5772 5773 // Even when parallel reference processing is enabled, the processing 5774 // of JNI refs is serial and performed serially by the current thread 5775 // rather than by a worker. The following PSS will be used for processing 5776 // JNI refs. 5777 5778 // Use only a single queue for this PSS. 5779 G1ParScanThreadState pss(this, 0, NULL); 5780 5781 // We do not embed a reference processor in the copying/scanning 5782 // closures while we're actually processing the discovered 5783 // reference objects. 5784 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL); 5785 5786 pss.set_evac_failure_closure(&evac_failure_cl); 5787 5788 assert(pss.queue_is_empty(), "pre-condition"); 5789 5790 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL); 5791 5792 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL); 5793 5794 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5795 5796 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5797 // We also need to mark copied objects. 5798 copy_non_heap_cl = ©_mark_non_heap_cl; 5799 } 5800 5801 // Keep alive closure. 5802 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, &pss); 5803 5804 // Serial Complete GC closure 5805 G1STWDrainQueueClosure drain_queue(this, &pss); 5806 5807 // Setup the soft refs policy... 5808 rp->setup_policy(false); 5809 5810 ReferenceProcessorStats stats; 5811 if (!rp->processing_is_mt()) { 5812 // Serial reference processing... 5813 stats = rp->process_discovered_references(&is_alive, 5814 &keep_alive, 5815 &drain_queue, 5816 NULL, 5817 _gc_timer_stw, 5818 _gc_tracer_stw->gc_id()); 5819 } else { 5820 // Parallel reference processing 5821 assert(rp->num_q() == no_of_gc_workers, "sanity"); 5822 assert(no_of_gc_workers <= rp->max_num_q(), "sanity"); 5823 5824 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers); 5825 stats = rp->process_discovered_references(&is_alive, 5826 &keep_alive, 5827 &drain_queue, 5828 &par_task_executor, 5829 _gc_timer_stw, 5830 _gc_tracer_stw->gc_id()); 5831 } 5832 5833 _gc_tracer_stw->report_gc_reference_stats(stats); 5834 5835 // We have completed copying any necessary live referent objects. 5836 assert(pss.queue_is_empty(), "both queue and overflow should be empty"); 5837 5838 double ref_proc_time = os::elapsedTime() - ref_proc_start; 5839 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 5840 } 5841 5842 // Weak Reference processing during an evacuation pause (part 2). 5843 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) { 5844 double ref_enq_start = os::elapsedTime(); 5845 5846 ReferenceProcessor* rp = _ref_processor_stw; 5847 assert(!rp->discovery_enabled(), "should have been disabled as part of processing"); 5848 5849 // Now enqueue any remaining on the discovered lists on to 5850 // the pending list. 5851 if (!rp->processing_is_mt()) { 5852 // Serial reference processing... 5853 rp->enqueue_discovered_references(); 5854 } else { 5855 // Parallel reference enqueueing 5856 5857 assert(no_of_gc_workers == workers()->active_workers(), 5858 "Need to reset active workers"); 5859 assert(rp->num_q() == no_of_gc_workers, "sanity"); 5860 assert(no_of_gc_workers <= rp->max_num_q(), "sanity"); 5861 5862 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers); 5863 rp->enqueue_discovered_references(&par_task_executor); 5864 } 5865 5866 rp->verify_no_references_recorded(); 5867 assert(!rp->discovery_enabled(), "should have been disabled"); 5868 5869 // FIXME 5870 // CM's reference processing also cleans up the string and symbol tables. 5871 // Should we do that here also? We could, but it is a serial operation 5872 // and could significantly increase the pause time. 5873 5874 double ref_enq_time = os::elapsedTime() - ref_enq_start; 5875 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0); 5876 } 5877 5878 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) { 5879 _expand_heap_after_alloc_failure = true; 5880 _evacuation_failed = false; 5881 5882 // Should G1EvacuationFailureALot be in effect for this GC? 5883 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) 5884 5885 g1_rem_set()->prepare_for_oops_into_collection_set_do(); 5886 5887 // Disable the hot card cache. 5888 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 5889 hot_card_cache->reset_hot_cache_claimed_index(); 5890 hot_card_cache->set_use_cache(false); 5891 5892 uint n_workers; 5893 if (G1CollectedHeap::use_parallel_gc_threads()) { 5894 n_workers = 5895 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 5896 workers()->active_workers(), 5897 Threads::number_of_non_daemon_threads()); 5898 assert(UseDynamicNumberOfGCThreads || 5899 n_workers == workers()->total_workers(), 5900 "If not dynamic should be using all the workers"); 5901 workers()->set_active_workers(n_workers); 5902 set_par_threads(n_workers); 5903 } else { 5904 assert(n_par_threads() == 0, 5905 "Should be the original non-parallel value"); 5906 n_workers = 1; 5907 } 5908 5909 G1ParTask g1_par_task(this, _task_queues); 5910 5911 init_for_evac_failure(NULL); 5912 5913 rem_set()->prepare_for_younger_refs_iterate(true); 5914 5915 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty"); 5916 double start_par_time_sec = os::elapsedTime(); 5917 double end_par_time_sec; 5918 5919 { 5920 StrongRootsScope srs(this); 5921 // InitialMark needs claim bits to keep track of the marked-through CLDs. 5922 if (g1_policy()->during_initial_mark_pause()) { 5923 ClassLoaderDataGraph::clear_claimed_marks(); 5924 } 5925 5926 if (G1CollectedHeap::use_parallel_gc_threads()) { 5927 // The individual threads will set their evac-failure closures. 5928 if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr(); 5929 // These tasks use ShareHeap::_process_strong_tasks 5930 assert(UseDynamicNumberOfGCThreads || 5931 workers()->active_workers() == workers()->total_workers(), 5932 "If not dynamic should be using all the workers"); 5933 workers()->run_task(&g1_par_task); 5934 } else { 5935 g1_par_task.set_for_termination(n_workers); 5936 g1_par_task.work(0); 5937 } 5938 end_par_time_sec = os::elapsedTime(); 5939 5940 // Closing the inner scope will execute the destructor 5941 // for the StrongRootsScope object. We record the current 5942 // elapsed time before closing the scope so that time 5943 // taken for the SRS destructor is NOT included in the 5944 // reported parallel time. 5945 } 5946 5947 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0; 5948 g1_policy()->phase_times()->record_par_time(par_time_ms); 5949 5950 double code_root_fixup_time_ms = 5951 (os::elapsedTime() - end_par_time_sec) * 1000.0; 5952 g1_policy()->phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms); 5953 5954 set_par_threads(0); 5955 5956 // Process any discovered reference objects - we have 5957 // to do this _before_ we retire the GC alloc regions 5958 // as we may have to copy some 'reachable' referent 5959 // objects (and their reachable sub-graphs) that were 5960 // not copied during the pause. 5961 process_discovered_references(n_workers); 5962 5963 // Weak root processing. 5964 { 5965 G1STWIsAliveClosure is_alive(this); 5966 G1KeepAliveClosure keep_alive(this); 5967 JNIHandles::weak_oops_do(&is_alive, &keep_alive); 5968 if (G1StringDedup::is_enabled()) { 5969 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive); 5970 } 5971 } 5972 5973 release_gc_alloc_regions(n_workers, evacuation_info); 5974 g1_rem_set()->cleanup_after_oops_into_collection_set_do(); 5975 5976 // Reset and re-enable the hot card cache. 5977 // Note the counts for the cards in the regions in the 5978 // collection set are reset when the collection set is freed. 5979 hot_card_cache->reset_hot_cache(); 5980 hot_card_cache->set_use_cache(true); 5981 5982 // Migrate the strong code roots attached to each region in 5983 // the collection set. Ideally we would like to do this 5984 // after we have finished the scanning/evacuation of the 5985 // strong code roots for a particular heap region. 5986 migrate_strong_code_roots(); 5987 5988 purge_code_root_memory(); 5989 5990 if (g1_policy()->during_initial_mark_pause()) { 5991 // Reset the claim values set during marking the strong code roots 5992 reset_heap_region_claim_values(); 5993 } 5994 5995 finalize_for_evac_failure(); 5996 5997 if (evacuation_failed()) { 5998 remove_self_forwarding_pointers(); 5999 6000 // Reset the G1EvacuationFailureALot counters and flags 6001 // Note: the values are reset only when an actual 6002 // evacuation failure occurs. 6003 NOT_PRODUCT(reset_evacuation_should_fail();) 6004 } 6005 6006 // Enqueue any remaining references remaining on the STW 6007 // reference processor's discovered lists. We need to do 6008 // this after the card table is cleaned (and verified) as 6009 // the act of enqueueing entries on to the pending list 6010 // will log these updates (and dirty their associated 6011 // cards). We need these updates logged to update any 6012 // RSets. 6013 enqueue_discovered_references(n_workers); 6014 6015 if (G1DeferredRSUpdate) { 6016 redirty_logged_cards(); 6017 } 6018 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 6019 } 6020 6021 void G1CollectedHeap::free_region(HeapRegion* hr, 6022 FreeRegionList* free_list, 6023 bool par, 6024 bool locked) { 6025 assert(!hr->isHumongous(), "this is only for non-humongous regions"); 6026 assert(!hr->is_empty(), "the region should not be empty"); 6027 assert(_hrs.is_available(hr->hrs_index()), "region should be committed"); 6028 assert(free_list != NULL, "pre-condition"); 6029 6030 if (G1VerifyBitmaps) { 6031 MemRegion mr(hr->bottom(), hr->end()); 6032 concurrent_mark()->clearRangePrevBitmap(mr); 6033 } 6034 6035 // Clear the card counts for this region. 6036 // Note: we only need to do this if the region is not young 6037 // (since we don't refine cards in young regions). 6038 if (!hr->is_young()) { 6039 _cg1r->hot_card_cache()->reset_card_counts(hr); 6040 } 6041 hr->hr_clear(par, true /* clear_space */, locked /* locked */); 6042 free_list->add_ordered(hr); 6043 } 6044 6045 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 6046 FreeRegionList* free_list, 6047 bool par) { 6048 assert(hr->startsHumongous(), "this is only for starts humongous regions"); 6049 assert(free_list != NULL, "pre-condition"); 6050 6051 size_t hr_capacity = hr->capacity(); 6052 // We need to read this before we make the region non-humongous, 6053 // otherwise the information will be gone. 6054 uint last_index = hr->last_hc_index(); 6055 hr->set_notHumongous(); 6056 free_region(hr, free_list, par); 6057 6058 uint i = hr->hrs_index() + 1; 6059 while (i < last_index) { 6060 HeapRegion* curr_hr = region_at(i); 6061 assert(curr_hr->continuesHumongous(), "invariant"); 6062 curr_hr->set_notHumongous(); 6063 free_region(curr_hr, free_list, par); 6064 i += 1; 6065 } 6066 } 6067 6068 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed, 6069 const HeapRegionSetCount& humongous_regions_removed) { 6070 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) { 6071 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 6072 _old_set.bulk_remove(old_regions_removed); 6073 _humongous_set.bulk_remove(humongous_regions_removed); 6074 } 6075 6076 } 6077 6078 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) { 6079 assert(list != NULL, "list can't be null"); 6080 if (!list->is_empty()) { 6081 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag); 6082 _hrs.insert_list_into_free_list(list); 6083 } 6084 } 6085 6086 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) { 6087 assert(_summary_bytes_used >= bytes, 6088 err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" should be >= bytes: "SIZE_FORMAT, 6089 _summary_bytes_used, bytes)); 6090 _summary_bytes_used -= bytes; 6091 } 6092 6093 class G1ParCleanupCTTask : public AbstractGangTask { 6094 G1SATBCardTableModRefBS* _ct_bs; 6095 G1CollectedHeap* _g1h; 6096 HeapRegion* volatile _su_head; 6097 public: 6098 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs, 6099 G1CollectedHeap* g1h) : 6100 AbstractGangTask("G1 Par Cleanup CT Task"), 6101 _ct_bs(ct_bs), _g1h(g1h) { } 6102 6103 void work(uint worker_id) { 6104 HeapRegion* r; 6105 while (r = _g1h->pop_dirty_cards_region()) { 6106 clear_cards(r); 6107 } 6108 } 6109 6110 void clear_cards(HeapRegion* r) { 6111 // Cards of the survivors should have already been dirtied. 6112 if (!r->is_survivor()) { 6113 _ct_bs->clear(MemRegion(r->bottom(), r->end())); 6114 } 6115 } 6116 }; 6117 6118 #ifndef PRODUCT 6119 class G1VerifyCardTableCleanup: public HeapRegionClosure { 6120 G1CollectedHeap* _g1h; 6121 G1SATBCardTableModRefBS* _ct_bs; 6122 public: 6123 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs) 6124 : _g1h(g1h), _ct_bs(ct_bs) { } 6125 virtual bool doHeapRegion(HeapRegion* r) { 6126 if (r->is_survivor()) { 6127 _g1h->verify_dirty_region(r); 6128 } else { 6129 _g1h->verify_not_dirty_region(r); 6130 } 6131 return false; 6132 } 6133 }; 6134 6135 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) { 6136 // All of the region should be clean. 6137 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 6138 MemRegion mr(hr->bottom(), hr->end()); 6139 ct_bs->verify_not_dirty_region(mr); 6140 } 6141 6142 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) { 6143 // We cannot guarantee that [bottom(),end()] is dirty. Threads 6144 // dirty allocated blocks as they allocate them. The thread that 6145 // retires each region and replaces it with a new one will do a 6146 // maximal allocation to fill in [pre_dummy_top(),end()] but will 6147 // not dirty that area (one less thing to have to do while holding 6148 // a lock). So we can only verify that [bottom(),pre_dummy_top()] 6149 // is dirty. 6150 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 6151 MemRegion mr(hr->bottom(), hr->pre_dummy_top()); 6152 if (hr->is_young()) { 6153 ct_bs->verify_g1_young_region(mr); 6154 } else { 6155 ct_bs->verify_dirty_region(mr); 6156 } 6157 } 6158 6159 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) { 6160 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 6161 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) { 6162 verify_dirty_region(hr); 6163 } 6164 } 6165 6166 void G1CollectedHeap::verify_dirty_young_regions() { 6167 verify_dirty_young_list(_young_list->first_region()); 6168 } 6169 6170 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap, 6171 HeapWord* tams, HeapWord* end) { 6172 guarantee(tams <= end, 6173 err_msg("tams: "PTR_FORMAT" end: "PTR_FORMAT, tams, end)); 6174 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end); 6175 if (result < end) { 6176 gclog_or_tty->cr(); 6177 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: "PTR_FORMAT, 6178 bitmap_name, result); 6179 gclog_or_tty->print_cr("## %s tams: "PTR_FORMAT" end: "PTR_FORMAT, 6180 bitmap_name, tams, end); 6181 return false; 6182 } 6183 return true; 6184 } 6185 6186 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) { 6187 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap(); 6188 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap(); 6189 6190 HeapWord* bottom = hr->bottom(); 6191 HeapWord* ptams = hr->prev_top_at_mark_start(); 6192 HeapWord* ntams = hr->next_top_at_mark_start(); 6193 HeapWord* end = hr->end(); 6194 6195 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end); 6196 6197 bool res_n = true; 6198 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window 6199 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap 6200 // if we happen to be in that state. 6201 if (mark_in_progress() || !_cmThread->in_progress()) { 6202 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end); 6203 } 6204 if (!res_p || !res_n) { 6205 gclog_or_tty->print_cr("#### Bitmap verification failed for "HR_FORMAT, 6206 HR_FORMAT_PARAMS(hr)); 6207 gclog_or_tty->print_cr("#### Caller: %s", caller); 6208 return false; 6209 } 6210 return true; 6211 } 6212 6213 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) { 6214 if (!G1VerifyBitmaps) return; 6215 6216 guarantee(verify_bitmaps(caller, hr), "bitmap verification"); 6217 } 6218 6219 class G1VerifyBitmapClosure : public HeapRegionClosure { 6220 private: 6221 const char* _caller; 6222 G1CollectedHeap* _g1h; 6223 bool _failures; 6224 6225 public: 6226 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) : 6227 _caller(caller), _g1h(g1h), _failures(false) { } 6228 6229 bool failures() { return _failures; } 6230 6231 virtual bool doHeapRegion(HeapRegion* hr) { 6232 if (hr->continuesHumongous()) return false; 6233 6234 bool result = _g1h->verify_bitmaps(_caller, hr); 6235 if (!result) { 6236 _failures = true; 6237 } 6238 return false; 6239 } 6240 }; 6241 6242 void G1CollectedHeap::check_bitmaps(const char* caller) { 6243 if (!G1VerifyBitmaps) return; 6244 6245 G1VerifyBitmapClosure cl(caller, this); 6246 heap_region_iterate(&cl); 6247 guarantee(!cl.failures(), "bitmap verification"); 6248 } 6249 #endif // PRODUCT 6250 6251 void G1CollectedHeap::cleanUpCardTable() { 6252 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 6253 double start = os::elapsedTime(); 6254 6255 { 6256 // Iterate over the dirty cards region list. 6257 G1ParCleanupCTTask cleanup_task(ct_bs, this); 6258 6259 if (G1CollectedHeap::use_parallel_gc_threads()) { 6260 set_par_threads(); 6261 workers()->run_task(&cleanup_task); 6262 set_par_threads(0); 6263 } else { 6264 while (_dirty_cards_region_list) { 6265 HeapRegion* r = _dirty_cards_region_list; 6266 cleanup_task.clear_cards(r); 6267 _dirty_cards_region_list = r->get_next_dirty_cards_region(); 6268 if (_dirty_cards_region_list == r) { 6269 // The last region. 6270 _dirty_cards_region_list = NULL; 6271 } 6272 r->set_next_dirty_cards_region(NULL); 6273 } 6274 } 6275 #ifndef PRODUCT 6276 if (G1VerifyCTCleanup || VerifyAfterGC) { 6277 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs); 6278 heap_region_iterate(&cleanup_verifier); 6279 } 6280 #endif 6281 } 6282 6283 double elapsed = os::elapsedTime() - start; 6284 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0); 6285 } 6286 6287 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) { 6288 size_t pre_used = 0; 6289 FreeRegionList local_free_list("Local List for CSet Freeing"); 6290 6291 double young_time_ms = 0.0; 6292 double non_young_time_ms = 0.0; 6293 6294 // Since the collection set is a superset of the the young list, 6295 // all we need to do to clear the young list is clear its 6296 // head and length, and unlink any young regions in the code below 6297 _young_list->clear(); 6298 6299 G1CollectorPolicy* policy = g1_policy(); 6300 6301 double start_sec = os::elapsedTime(); 6302 bool non_young = true; 6303 6304 HeapRegion* cur = cs_head; 6305 int age_bound = -1; 6306 size_t rs_lengths = 0; 6307 6308 while (cur != NULL) { 6309 assert(!is_on_master_free_list(cur), "sanity"); 6310 if (non_young) { 6311 if (cur->is_young()) { 6312 double end_sec = os::elapsedTime(); 6313 double elapsed_ms = (end_sec - start_sec) * 1000.0; 6314 non_young_time_ms += elapsed_ms; 6315 6316 start_sec = os::elapsedTime(); 6317 non_young = false; 6318 } 6319 } else { 6320 if (!cur->is_young()) { 6321 double end_sec = os::elapsedTime(); 6322 double elapsed_ms = (end_sec - start_sec) * 1000.0; 6323 young_time_ms += elapsed_ms; 6324 6325 start_sec = os::elapsedTime(); 6326 non_young = true; 6327 } 6328 } 6329 6330 rs_lengths += cur->rem_set()->occupied_locked(); 6331 6332 HeapRegion* next = cur->next_in_collection_set(); 6333 assert(cur->in_collection_set(), "bad CS"); 6334 cur->set_next_in_collection_set(NULL); 6335 cur->set_in_collection_set(false); 6336 6337 if (cur->is_young()) { 6338 int index = cur->young_index_in_cset(); 6339 assert(index != -1, "invariant"); 6340 assert((uint) index < policy->young_cset_region_length(), "invariant"); 6341 size_t words_survived = _surviving_young_words[index]; 6342 cur->record_surv_words_in_group(words_survived); 6343 6344 // At this point the we have 'popped' cur from the collection set 6345 // (linked via next_in_collection_set()) but it is still in the 6346 // young list (linked via next_young_region()). Clear the 6347 // _next_young_region field. 6348 cur->set_next_young_region(NULL); 6349 } else { 6350 int index = cur->young_index_in_cset(); 6351 assert(index == -1, "invariant"); 6352 } 6353 6354 assert( (cur->is_young() && cur->young_index_in_cset() > -1) || 6355 (!cur->is_young() && cur->young_index_in_cset() == -1), 6356 "invariant" ); 6357 6358 if (!cur->evacuation_failed()) { 6359 MemRegion used_mr = cur->used_region(); 6360 6361 // And the region is empty. 6362 assert(!used_mr.is_empty(), "Should not have empty regions in a CS."); 6363 pre_used += cur->used(); 6364 free_region(cur, &local_free_list, false /* par */, true /* locked */); 6365 } else { 6366 cur->uninstall_surv_rate_group(); 6367 if (cur->is_young()) { 6368 cur->set_young_index_in_cset(-1); 6369 } 6370 cur->set_not_young(); 6371 cur->set_evacuation_failed(false); 6372 // The region is now considered to be old. 6373 _old_set.add(cur); 6374 evacuation_info.increment_collectionset_used_after(cur->used()); 6375 } 6376 cur = next; 6377 } 6378 6379 evacuation_info.set_regions_freed(local_free_list.length()); 6380 policy->record_max_rs_lengths(rs_lengths); 6381 policy->cset_regions_freed(); 6382 6383 double end_sec = os::elapsedTime(); 6384 double elapsed_ms = (end_sec - start_sec) * 1000.0; 6385 6386 if (non_young) { 6387 non_young_time_ms += elapsed_ms; 6388 } else { 6389 young_time_ms += elapsed_ms; 6390 } 6391 6392 prepend_to_freelist(&local_free_list); 6393 decrement_summary_bytes(pre_used); 6394 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms); 6395 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms); 6396 } 6397 6398 class G1FreeHumongousRegionClosure : public HeapRegionClosure { 6399 private: 6400 FreeRegionList* _free_region_list; 6401 HeapRegionSet* _proxy_set; 6402 HeapRegionSetCount _humongous_regions_removed; 6403 size_t _freed_bytes; 6404 public: 6405 6406 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) : 6407 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) { 6408 } 6409 6410 virtual bool doHeapRegion(HeapRegion* r) { 6411 if (!r->startsHumongous()) { 6412 return false; 6413 } 6414 6415 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 6416 6417 oop obj = (oop)r->bottom(); 6418 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap(); 6419 6420 // The following checks whether the humongous object is live are sufficient. 6421 // The main additional check (in addition to having a reference from the roots 6422 // or the young gen) is whether the humongous object has a remembered set entry. 6423 // 6424 // A humongous object cannot be live if there is no remembered set for it 6425 // because: 6426 // - there can be no references from within humongous starts regions referencing 6427 // the object because we never allocate other objects into them. 6428 // (I.e. there are no intra-region references that may be missed by the 6429 // remembered set) 6430 // - as soon there is a remembered set entry to the humongous starts region 6431 // (i.e. it has "escaped" to an old object) this remembered set entry will stay 6432 // until the end of a concurrent mark. 6433 // 6434 // It is not required to check whether the object has been found dead by marking 6435 // or not, in fact it would prevent reclamation within a concurrent cycle, as 6436 // all objects allocated during that time are considered live. 6437 // SATB marking is even more conservative than the remembered set. 6438 // So if at this point in the collection there is no remembered set entry, 6439 // nobody has a reference to it. 6440 // At the start of collection we flush all refinement logs, and remembered sets 6441 // are completely up-to-date wrt to references to the humongous object. 6442 // 6443 // Other implementation considerations: 6444 // - never consider object arrays: while they are a valid target, they have not 6445 // been observed to be used as temporary objects. 6446 // - they would also pose considerable effort for cleaning up the the remembered 6447 // sets. 6448 // While this cleanup is not strictly necessary to be done (or done instantly), 6449 // given that their occurrence is very low, this saves us this additional 6450 // complexity. 6451 uint region_idx = r->hrs_index(); 6452 if (g1h->humongous_is_live(region_idx) || 6453 g1h->humongous_region_is_always_live(region_idx)) { 6454 6455 if (G1TraceReclaimDeadHumongousObjectsAtYoungGC) { 6456 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", 6457 r->isHumongous(), 6458 region_idx, 6459 r->rem_set()->occupied(), 6460 r->rem_set()->strong_code_roots_list_length(), 6461 next_bitmap->isMarked(r->bottom()), 6462 g1h->humongous_is_live(region_idx), 6463 obj->is_objArray() 6464 ); 6465 } 6466 6467 return false; 6468 } 6469 6470 guarantee(!obj->is_objArray(), 6471 err_msg("Eagerly reclaiming object arrays is not supported, but the object "PTR_FORMAT" is.", 6472 r->bottom())); 6473 6474 if (G1TraceReclaimDeadHumongousObjectsAtYoungGC) { 6475 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", 6476 r->isHumongous(), 6477 r->bottom(), 6478 region_idx, 6479 r->region_num(), 6480 r->rem_set()->occupied(), 6481 r->rem_set()->strong_code_roots_list_length(), 6482 next_bitmap->isMarked(r->bottom()), 6483 g1h->humongous_is_live(region_idx), 6484 obj->is_objArray() 6485 ); 6486 } 6487 // Need to clear mark bit of the humongous object if already set. 6488 if (next_bitmap->isMarked(r->bottom())) { 6489 next_bitmap->clear(r->bottom()); 6490 } 6491 _freed_bytes += r->used(); 6492 r->set_containing_set(NULL); 6493 _humongous_regions_removed.increment(1u, r->capacity()); 6494 g1h->free_humongous_region(r, _free_region_list, false); 6495 6496 return false; 6497 } 6498 6499 HeapRegionSetCount& humongous_free_count() { 6500 return _humongous_regions_removed; 6501 } 6502 6503 size_t bytes_freed() const { 6504 return _freed_bytes; 6505 } 6506 6507 size_t humongous_reclaimed() const { 6508 return _humongous_regions_removed.length(); 6509 } 6510 }; 6511 6512 void G1CollectedHeap::eagerly_reclaim_humongous_regions() { 6513 assert_at_safepoint(true); 6514 6515 if (!G1ReclaimDeadHumongousObjectsAtYoungGC || !_has_humongous_reclaim_candidates) { 6516 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0); 6517 return; 6518 } 6519 6520 double start_time = os::elapsedTime(); 6521 6522 FreeRegionList local_cleanup_list("Local Humongous Cleanup List"); 6523 6524 G1FreeHumongousRegionClosure cl(&local_cleanup_list); 6525 heap_region_iterate(&cl); 6526 6527 HeapRegionSetCount empty_set; 6528 remove_from_old_sets(empty_set, cl.humongous_free_count()); 6529 6530 G1HRPrinter* hr_printer = _g1h->hr_printer(); 6531 if (hr_printer->is_active()) { 6532 FreeRegionListIterator iter(&local_cleanup_list); 6533 while (iter.more_available()) { 6534 HeapRegion* hr = iter.get_next(); 6535 hr_printer->cleanup(hr); 6536 } 6537 } 6538 6539 prepend_to_freelist(&local_cleanup_list); 6540 decrement_summary_bytes(cl.bytes_freed()); 6541 6542 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0, 6543 cl.humongous_reclaimed()); 6544 } 6545 6546 // This routine is similar to the above but does not record 6547 // any policy statistics or update free lists; we are abandoning 6548 // the current incremental collection set in preparation of a 6549 // full collection. After the full GC we will start to build up 6550 // the incremental collection set again. 6551 // This is only called when we're doing a full collection 6552 // and is immediately followed by the tearing down of the young list. 6553 6554 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) { 6555 HeapRegion* cur = cs_head; 6556 6557 while (cur != NULL) { 6558 HeapRegion* next = cur->next_in_collection_set(); 6559 assert(cur->in_collection_set(), "bad CS"); 6560 cur->set_next_in_collection_set(NULL); 6561 cur->set_in_collection_set(false); 6562 cur->set_young_index_in_cset(-1); 6563 cur = next; 6564 } 6565 } 6566 6567 void G1CollectedHeap::set_free_regions_coming() { 6568 if (G1ConcRegionFreeingVerbose) { 6569 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " 6570 "setting free regions coming"); 6571 } 6572 6573 assert(!free_regions_coming(), "pre-condition"); 6574 _free_regions_coming = true; 6575 } 6576 6577 void G1CollectedHeap::reset_free_regions_coming() { 6578 assert(free_regions_coming(), "pre-condition"); 6579 6580 { 6581 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6582 _free_regions_coming = false; 6583 SecondaryFreeList_lock->notify_all(); 6584 } 6585 6586 if (G1ConcRegionFreeingVerbose) { 6587 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " 6588 "reset free regions coming"); 6589 } 6590 } 6591 6592 void G1CollectedHeap::wait_while_free_regions_coming() { 6593 // Most of the time we won't have to wait, so let's do a quick test 6594 // first before we take the lock. 6595 if (!free_regions_coming()) { 6596 return; 6597 } 6598 6599 if (G1ConcRegionFreeingVerbose) { 6600 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " 6601 "waiting for free regions"); 6602 } 6603 6604 { 6605 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6606 while (free_regions_coming()) { 6607 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 6608 } 6609 } 6610 6611 if (G1ConcRegionFreeingVerbose) { 6612 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " 6613 "done waiting for free regions"); 6614 } 6615 } 6616 6617 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 6618 assert(heap_lock_held_for_gc(), 6619 "the heap lock should already be held by or for this thread"); 6620 _young_list->push_region(hr); 6621 } 6622 6623 class NoYoungRegionsClosure: public HeapRegionClosure { 6624 private: 6625 bool _success; 6626 public: 6627 NoYoungRegionsClosure() : _success(true) { } 6628 bool doHeapRegion(HeapRegion* r) { 6629 if (r->is_young()) { 6630 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young", 6631 r->bottom(), r->end()); 6632 _success = false; 6633 } 6634 return false; 6635 } 6636 bool success() { return _success; } 6637 }; 6638 6639 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) { 6640 bool ret = _young_list->check_list_empty(check_sample); 6641 6642 if (check_heap) { 6643 NoYoungRegionsClosure closure; 6644 heap_region_iterate(&closure); 6645 ret = ret && closure.success(); 6646 } 6647 6648 return ret; 6649 } 6650 6651 class TearDownRegionSetsClosure : public HeapRegionClosure { 6652 private: 6653 HeapRegionSet *_old_set; 6654 6655 public: 6656 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { } 6657 6658 bool doHeapRegion(HeapRegion* r) { 6659 if (r->is_empty()) { 6660 // We ignore empty regions, we'll empty the free list afterwards 6661 } else if (r->is_young()) { 6662 // We ignore young regions, we'll empty the young list afterwards 6663 } else if (r->isHumongous()) { 6664 // We ignore humongous regions, we're not tearing down the 6665 // humongous region set 6666 } else { 6667 // The rest should be old 6668 _old_set->remove(r); 6669 } 6670 return false; 6671 } 6672 6673 ~TearDownRegionSetsClosure() { 6674 assert(_old_set->is_empty(), "post-condition"); 6675 } 6676 }; 6677 6678 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) { 6679 assert_at_safepoint(true /* should_be_vm_thread */); 6680 6681 if (!free_list_only) { 6682 TearDownRegionSetsClosure cl(&_old_set); 6683 heap_region_iterate(&cl); 6684 6685 // Note that emptying the _young_list is postponed and instead done as 6686 // the first step when rebuilding the regions sets again. The reason for 6687 // this is that during a full GC string deduplication needs to know if 6688 // a collected region was young or old when the full GC was initiated. 6689 } 6690 _hrs.remove_all_free_regions(); 6691 } 6692 6693 class RebuildRegionSetsClosure : public HeapRegionClosure { 6694 private: 6695 bool _free_list_only; 6696 HeapRegionSet* _old_set; 6697 HeapRegionSeq* _hrs; 6698 size_t _total_used; 6699 6700 public: 6701 RebuildRegionSetsClosure(bool free_list_only, 6702 HeapRegionSet* old_set, HeapRegionSeq* hrs) : 6703 _free_list_only(free_list_only), 6704 _old_set(old_set), _hrs(hrs), _total_used(0) { 6705 assert(_hrs->num_free_regions() == 0, "pre-condition"); 6706 if (!free_list_only) { 6707 assert(_old_set->is_empty(), "pre-condition"); 6708 } 6709 } 6710 6711 bool doHeapRegion(HeapRegion* r) { 6712 if (r->continuesHumongous()) { 6713 return false; 6714 } 6715 6716 if (r->is_empty()) { 6717 // Add free regions to the free list 6718 _hrs->insert_into_free_list(r); 6719 } else if (!_free_list_only) { 6720 assert(!r->is_young(), "we should not come across young regions"); 6721 6722 if (r->isHumongous()) { 6723 // We ignore humongous regions, we left the humongous set unchanged 6724 } else { 6725 // The rest should be old, add them to the old set 6726 _old_set->add(r); 6727 } 6728 _total_used += r->used(); 6729 } 6730 6731 return false; 6732 } 6733 6734 size_t total_used() { 6735 return _total_used; 6736 } 6737 }; 6738 6739 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { 6740 assert_at_safepoint(true /* should_be_vm_thread */); 6741 6742 if (!free_list_only) { 6743 _young_list->empty_list(); 6744 } 6745 6746 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrs); 6747 heap_region_iterate(&cl); 6748 6749 if (!free_list_only) { 6750 _summary_bytes_used = cl.total_used(); 6751 } 6752 assert(_summary_bytes_used == recalculate_used(), 6753 err_msg("inconsistent _summary_bytes_used, " 6754 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT, 6755 _summary_bytes_used, recalculate_used())); 6756 } 6757 6758 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) { 6759 _refine_cte_cl->set_concurrent(concurrent); 6760 } 6761 6762 bool G1CollectedHeap::is_in_closed_subset(const void* p) const { 6763 HeapRegion* hr = heap_region_containing(p); 6764 return hr->is_in(p); 6765 } 6766 6767 // Methods for the mutator alloc region 6768 6769 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 6770 bool force) { 6771 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6772 assert(!force || g1_policy()->can_expand_young_list(), 6773 "if force is true we should be able to expand the young list"); 6774 bool young_list_full = g1_policy()->is_young_list_full(); 6775 if (force || !young_list_full) { 6776 HeapRegion* new_alloc_region = new_region(word_size, 6777 false /* is_old */, 6778 false /* do_expand */); 6779 if (new_alloc_region != NULL) { 6780 set_region_short_lived_locked(new_alloc_region); 6781 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full); 6782 check_bitmaps("Mutator Region Allocation", new_alloc_region); 6783 return new_alloc_region; 6784 } 6785 } 6786 return NULL; 6787 } 6788 6789 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 6790 size_t allocated_bytes) { 6791 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6792 assert(alloc_region->is_young(), "all mutator alloc regions should be young"); 6793 6794 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region); 6795 _summary_bytes_used += allocated_bytes; 6796 _hr_printer.retire(alloc_region); 6797 // We update the eden sizes here, when the region is retired, 6798 // instead of when it's allocated, since this is the point that its 6799 // used space has been recored in _summary_bytes_used. 6800 g1mm()->update_eden_size(); 6801 } 6802 6803 HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size, 6804 bool force) { 6805 return _g1h->new_mutator_alloc_region(word_size, force); 6806 } 6807 6808 void G1CollectedHeap::set_par_threads() { 6809 // Don't change the number of workers. Use the value previously set 6810 // in the workgroup. 6811 assert(G1CollectedHeap::use_parallel_gc_threads(), "shouldn't be here otherwise"); 6812 uint n_workers = workers()->active_workers(); 6813 assert(UseDynamicNumberOfGCThreads || 6814 n_workers == workers()->total_workers(), 6815 "Otherwise should be using the total number of workers"); 6816 if (n_workers == 0) { 6817 assert(false, "Should have been set in prior evacuation pause."); 6818 n_workers = ParallelGCThreads; 6819 workers()->set_active_workers(n_workers); 6820 } 6821 set_par_threads(n_workers); 6822 } 6823 6824 void MutatorAllocRegion::retire_region(HeapRegion* alloc_region, 6825 size_t allocated_bytes) { 6826 _g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes); 6827 } 6828 6829 // Methods for the GC alloc regions 6830 6831 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, 6832 uint count, 6833 GCAllocPurpose ap) { 6834 assert(FreeList_lock->owned_by_self(), "pre-condition"); 6835 6836 if (count < g1_policy()->max_regions(ap)) { 6837 bool survivor = (ap == GCAllocForSurvived); 6838 HeapRegion* new_alloc_region = new_region(word_size, 6839 !survivor, 6840 true /* do_expand */); 6841 if (new_alloc_region != NULL) { 6842 // We really only need to do this for old regions given that we 6843 // should never scan survivors. But it doesn't hurt to do it 6844 // for survivors too. 6845 new_alloc_region->record_top_and_timestamp(); 6846 if (survivor) { 6847 new_alloc_region->set_survivor(); 6848 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor); 6849 check_bitmaps("Survivor Region Allocation", new_alloc_region); 6850 } else { 6851 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old); 6852 check_bitmaps("Old Region Allocation", new_alloc_region); 6853 } 6854 bool during_im = g1_policy()->during_initial_mark_pause(); 6855 new_alloc_region->note_start_of_copying(during_im); 6856 return new_alloc_region; 6857 } else { 6858 g1_policy()->note_alloc_region_limit_reached(ap); 6859 } 6860 } 6861 return NULL; 6862 } 6863 6864 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 6865 size_t allocated_bytes, 6866 GCAllocPurpose ap) { 6867 bool during_im = g1_policy()->during_initial_mark_pause(); 6868 alloc_region->note_end_of_copying(during_im); 6869 g1_policy()->record_bytes_copied_during_gc(allocated_bytes); 6870 if (ap == GCAllocForSurvived) { 6871 young_list()->add_survivor_region(alloc_region); 6872 } else { 6873 _old_set.add(alloc_region); 6874 } 6875 _hr_printer.retire(alloc_region); 6876 } 6877 6878 HeapRegion* SurvivorGCAllocRegion::allocate_new_region(size_t word_size, 6879 bool force) { 6880 assert(!force, "not supported for GC alloc regions"); 6881 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForSurvived); 6882 } 6883 6884 void SurvivorGCAllocRegion::retire_region(HeapRegion* alloc_region, 6885 size_t allocated_bytes) { 6886 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes, 6887 GCAllocForSurvived); 6888 } 6889 6890 HeapRegion* OldGCAllocRegion::allocate_new_region(size_t word_size, 6891 bool force) { 6892 assert(!force, "not supported for GC alloc regions"); 6893 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForTenured); 6894 } 6895 6896 void OldGCAllocRegion::retire_region(HeapRegion* alloc_region, 6897 size_t allocated_bytes) { 6898 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes, 6899 GCAllocForTenured); 6900 } 6901 6902 HeapRegion* OldGCAllocRegion::release() { 6903 HeapRegion* cur = get(); 6904 if (cur != NULL) { 6905 // Determine how far we are from the next card boundary. If it is smaller than 6906 // the minimum object size we can allocate into, expand into the next card. 6907 HeapWord* top = cur->top(); 6908 HeapWord* aligned_top = (HeapWord*)align_ptr_up(top, G1BlockOffsetSharedArray::N_bytes); 6909 6910 size_t to_allocate_words = pointer_delta(aligned_top, top, HeapWordSize); 6911 6912 if (to_allocate_words != 0) { 6913 // We are not at a card boundary. Fill up, possibly into the next, taking the 6914 // end of the region and the minimum object size into account. 6915 to_allocate_words = MIN2(pointer_delta(cur->end(), cur->top(), HeapWordSize), 6916 MAX2(to_allocate_words, G1CollectedHeap::min_fill_size())); 6917 6918 // Skip allocation if there is not enough space to allocate even the smallest 6919 // possible object. In this case this region will not be retained, so the 6920 // original problem cannot occur. 6921 if (to_allocate_words >= G1CollectedHeap::min_fill_size()) { 6922 HeapWord* dummy = attempt_allocation(to_allocate_words, true /* bot_updates */); 6923 CollectedHeap::fill_with_object(dummy, to_allocate_words); 6924 } 6925 } 6926 } 6927 return G1AllocRegion::release(); 6928 } 6929 6930 // Heap region set verification 6931 6932 class VerifyRegionListsClosure : public HeapRegionClosure { 6933 private: 6934 HeapRegionSet* _old_set; 6935 HeapRegionSet* _humongous_set; 6936 HeapRegionSeq* _hrs; 6937 6938 public: 6939 HeapRegionSetCount _old_count; 6940 HeapRegionSetCount _humongous_count; 6941 HeapRegionSetCount _free_count; 6942 6943 VerifyRegionListsClosure(HeapRegionSet* old_set, 6944 HeapRegionSet* humongous_set, 6945 HeapRegionSeq* hrs) : 6946 _old_set(old_set), _humongous_set(humongous_set), _hrs(hrs), 6947 _old_count(), _humongous_count(), _free_count(){ } 6948 6949 bool doHeapRegion(HeapRegion* hr) { 6950 if (hr->continuesHumongous()) { 6951 return false; 6952 } 6953 6954 if (hr->is_young()) { 6955 // TODO 6956 } else if (hr->startsHumongous()) { 6957 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrs_index())); 6958 _humongous_count.increment(1u, hr->capacity()); 6959 } else if (hr->is_empty()) { 6960 assert(_hrs->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrs_index())); 6961 _free_count.increment(1u, hr->capacity()); 6962 } else { 6963 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrs_index())); 6964 _old_count.increment(1u, hr->capacity()); 6965 } 6966 return false; 6967 } 6968 6969 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionSeq* free_list) { 6970 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length())); 6971 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6972 old_set->total_capacity_bytes(), _old_count.capacity())); 6973 6974 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length())); 6975 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6976 humongous_set->total_capacity_bytes(), _humongous_count.capacity())); 6977 6978 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())); 6979 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6980 free_list->total_capacity_bytes(), _free_count.capacity())); 6981 } 6982 }; 6983 6984 void G1CollectedHeap::verify_region_sets() { 6985 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6986 6987 // First, check the explicit lists. 6988 _hrs.verify(); 6989 { 6990 // Given that a concurrent operation might be adding regions to 6991 // the secondary free list we have to take the lock before 6992 // verifying it. 6993 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6994 _secondary_free_list.verify_list(); 6995 } 6996 6997 // If a concurrent region freeing operation is in progress it will 6998 // be difficult to correctly attributed any free regions we come 6999 // across to the correct free list given that they might belong to 7000 // one of several (free_list, secondary_free_list, any local lists, 7001 // etc.). So, if that's the case we will skip the rest of the 7002 // verification operation. Alternatively, waiting for the concurrent 7003 // operation to complete will have a non-trivial effect on the GC's 7004 // operation (no concurrent operation will last longer than the 7005 // interval between two calls to verification) and it might hide 7006 // any issues that we would like to catch during testing. 7007 if (free_regions_coming()) { 7008 return; 7009 } 7010 7011 // Make sure we append the secondary_free_list on the free_list so 7012 // that all free regions we will come across can be safely 7013 // attributed to the free_list. 7014 append_secondary_free_list_if_not_empty_with_lock(); 7015 7016 // Finally, make sure that the region accounting in the lists is 7017 // consistent with what we see in the heap. 7018 7019 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrs); 7020 heap_region_iterate(&cl); 7021 cl.verify_counts(&_old_set, &_humongous_set, &_hrs); 7022 } 7023 7024 // Optimized nmethod scanning 7025 7026 class RegisterNMethodOopClosure: public OopClosure { 7027 G1CollectedHeap* _g1h; 7028 nmethod* _nm; 7029 7030 template <class T> void do_oop_work(T* p) { 7031 T heap_oop = oopDesc::load_heap_oop(p); 7032 if (!oopDesc::is_null(heap_oop)) { 7033 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 7034 HeapRegion* hr = _g1h->heap_region_containing(obj); 7035 assert(!hr->continuesHumongous(), 7036 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT 7037 " starting at "HR_FORMAT, 7038 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()))); 7039 7040 // HeapRegion::add_strong_code_root() avoids adding duplicate 7041 // entries but having duplicates is OK since we "mark" nmethods 7042 // as visited when we scan the strong code root lists during the GC. 7043 hr->add_strong_code_root(_nm); 7044 assert(hr->rem_set()->strong_code_roots_list_contains(_nm), 7045 err_msg("failed to add code root "PTR_FORMAT" to remembered set of region "HR_FORMAT, 7046 _nm, HR_FORMAT_PARAMS(hr))); 7047 } 7048 } 7049 7050 public: 7051 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 7052 _g1h(g1h), _nm(nm) {} 7053 7054 void do_oop(oop* p) { do_oop_work(p); } 7055 void do_oop(narrowOop* p) { do_oop_work(p); } 7056 }; 7057 7058 class UnregisterNMethodOopClosure: public OopClosure { 7059 G1CollectedHeap* _g1h; 7060 nmethod* _nm; 7061 7062 template <class T> void do_oop_work(T* p) { 7063 T heap_oop = oopDesc::load_heap_oop(p); 7064 if (!oopDesc::is_null(heap_oop)) { 7065 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 7066 HeapRegion* hr = _g1h->heap_region_containing(obj); 7067 assert(!hr->continuesHumongous(), 7068 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT 7069 " starting at "HR_FORMAT, 7070 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()))); 7071 7072 hr->remove_strong_code_root(_nm); 7073 assert(!hr->rem_set()->strong_code_roots_list_contains(_nm), 7074 err_msg("failed to remove code root "PTR_FORMAT" of region "HR_FORMAT, 7075 _nm, HR_FORMAT_PARAMS(hr))); 7076 } 7077 } 7078 7079 public: 7080 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 7081 _g1h(g1h), _nm(nm) {} 7082 7083 void do_oop(oop* p) { do_oop_work(p); } 7084 void do_oop(narrowOop* p) { do_oop_work(p); } 7085 }; 7086 7087 void G1CollectedHeap::register_nmethod(nmethod* nm) { 7088 CollectedHeap::register_nmethod(nm); 7089 7090 guarantee(nm != NULL, "sanity"); 7091 RegisterNMethodOopClosure reg_cl(this, nm); 7092 nm->oops_do(®_cl); 7093 } 7094 7095 void G1CollectedHeap::unregister_nmethod(nmethod* nm) { 7096 CollectedHeap::unregister_nmethod(nm); 7097 7098 guarantee(nm != NULL, "sanity"); 7099 UnregisterNMethodOopClosure reg_cl(this, nm); 7100 nm->oops_do(®_cl, true); 7101 } 7102 7103 class MigrateCodeRootsHeapRegionClosure: public HeapRegionClosure { 7104 public: 7105 bool doHeapRegion(HeapRegion *hr) { 7106 assert(!hr->isHumongous(), 7107 err_msg("humongous region "HR_FORMAT" should not have been added to collection set", 7108 HR_FORMAT_PARAMS(hr))); 7109 hr->migrate_strong_code_roots(); 7110 return false; 7111 } 7112 }; 7113 7114 void G1CollectedHeap::migrate_strong_code_roots() { 7115 MigrateCodeRootsHeapRegionClosure cl; 7116 double migrate_start = os::elapsedTime(); 7117 collection_set_iterate(&cl); 7118 double migration_time_ms = (os::elapsedTime() - migrate_start) * 1000.0; 7119 g1_policy()->phase_times()->record_strong_code_root_migration_time(migration_time_ms); 7120 } 7121 7122 void G1CollectedHeap::purge_code_root_memory() { 7123 double purge_start = os::elapsedTime(); 7124 G1CodeRootSet::purge_chunks(G1CodeRootsChunkCacheKeepPercent); 7125 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0; 7126 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms); 7127 } 7128 7129 class RebuildStrongCodeRootClosure: public CodeBlobClosure { 7130 G1CollectedHeap* _g1h; 7131 7132 public: 7133 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) : 7134 _g1h(g1h) {} 7135 7136 void do_code_blob(CodeBlob* cb) { 7137 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL; 7138 if (nm == NULL) { 7139 return; 7140 } 7141 7142 if (ScavengeRootsInCode) { 7143 _g1h->register_nmethod(nm); 7144 } 7145 } 7146 }; 7147 7148 void G1CollectedHeap::rebuild_strong_code_roots() { 7149 RebuildStrongCodeRootClosure blob_cl(this); 7150 CodeCache::blobs_do(&blob_cl); 7151 }