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