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/g1RemSet.inline.hpp" 48 #include "gc_implementation/g1/g1StringDedup.hpp" 49 #include "gc_implementation/g1/g1YCTypes.hpp" 50 #include "gc_implementation/g1/heapRegion.inline.hpp" 51 #include "gc_implementation/g1/heapRegionRemSet.hpp" 52 #include "gc_implementation/g1/heapRegionSeq.inline.hpp" 53 #include "gc_implementation/g1/vm_operations_g1.hpp" 54 #include "gc_implementation/shared/gcHeapSummary.hpp" 55 #include "gc_implementation/shared/gcTimer.hpp" 56 #include "gc_implementation/shared/gcTrace.hpp" 57 #include "gc_implementation/shared/gcTraceTime.hpp" 58 #include "gc_implementation/shared/isGCActiveMark.hpp" 59 #include "memory/gcLocker.inline.hpp" 60 #include "memory/generationSpec.hpp" 61 #include "memory/iterator.hpp" 62 #include "memory/referenceProcessor.hpp" 63 #include "oops/oop.inline.hpp" 64 #include "oops/oop.pcgc.inline.hpp" 65 #include "runtime/atomic.inline.hpp" 66 #include "runtime/prefetch.inline.hpp" 67 #include "runtime/orderAccess.inline.hpp" 68 #include "runtime/vmThread.hpp" 69 #include "utilities/globalDefinitions.hpp" 70 #include "utilities/ticks.hpp" 71 72 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0; 73 74 // turn it on so that the contents of the young list (scan-only / 75 // to-be-collected) are printed at "strategic" points before / during 76 // / after the collection --- this is useful for debugging 77 #define YOUNG_LIST_VERBOSE 0 78 // CURRENT STATUS 79 // This file is under construction. Search for "FIXME". 80 81 // INVARIANTS/NOTES 82 // 83 // All allocation activity covered by the G1CollectedHeap interface is 84 // serialized by acquiring the HeapLock. This happens in mem_allocate 85 // and allocate_new_tlab, which are the "entry" points to the 86 // allocation code from the rest of the JVM. (Note that this does not 87 // apply to TLAB allocation, which is not part of this interface: it 88 // is done by clients of this interface.) 89 90 // Notes on implementation of parallelism in different tasks. 91 // 92 // G1ParVerifyTask uses heap_region_par_iterate_chunked() for parallelism. 93 // The number of GC workers is passed to heap_region_par_iterate_chunked(). 94 // It does use run_task() which sets _n_workers in the task. 95 // G1ParTask executes g1_process_strong_roots() -> 96 // SharedHeap::process_strong_roots() which calls eventually to 97 // CardTableModRefBS::par_non_clean_card_iterate_work() which uses 98 // SequentialSubTasksDone. SharedHeap::process_strong_roots() also 99 // directly uses SubTasksDone (_process_strong_tasks field in SharedHeap). 100 // 101 102 // Local to this file. 103 104 class RefineCardTableEntryClosure: public CardTableEntryClosure { 105 bool _concurrent; 106 public: 107 RefineCardTableEntryClosure() : _concurrent(true) { } 108 109 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 110 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false); 111 // This path is executed by the concurrent refine or mutator threads, 112 // concurrently, and so we do not care if card_ptr contains references 113 // that point into the collection set. 114 assert(!oops_into_cset, "should be"); 115 116 if (_concurrent && SuspendibleThreadSet::should_yield()) { 117 // Caller will actually yield. 118 return false; 119 } 120 // Otherwise, we finished successfully; return true. 121 return true; 122 } 123 124 void set_concurrent(bool b) { _concurrent = b; } 125 }; 126 127 128 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure { 129 size_t _num_processed; 130 CardTableModRefBS* _ctbs; 131 int _histo[256]; 132 133 public: 134 ClearLoggedCardTableEntryClosure() : 135 _num_processed(0), _ctbs(G1CollectedHeap::heap()->g1_barrier_set()) 136 { 137 for (int i = 0; i < 256; i++) _histo[i] = 0; 138 } 139 140 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 141 unsigned char* ujb = (unsigned char*)card_ptr; 142 int ind = (int)(*ujb); 143 _histo[ind]++; 144 145 *card_ptr = (jbyte)CardTableModRefBS::clean_card_val(); 146 _num_processed++; 147 148 return true; 149 } 150 151 size_t num_processed() { return _num_processed; } 152 153 void print_histo() { 154 gclog_or_tty->print_cr("Card table value histogram:"); 155 for (int i = 0; i < 256; i++) { 156 if (_histo[i] != 0) { 157 gclog_or_tty->print_cr(" %d: %d", i, _histo[i]); 158 } 159 } 160 } 161 }; 162 163 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure { 164 private: 165 size_t _num_processed; 166 167 public: 168 RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { } 169 170 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 171 *card_ptr = CardTableModRefBS::dirty_card_val(); 172 _num_processed++; 173 return true; 174 } 175 176 size_t num_processed() const { return _num_processed; } 177 }; 178 179 YoungList::YoungList(G1CollectedHeap* g1h) : 180 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0), 181 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) { 182 guarantee(check_list_empty(false), "just making sure..."); 183 } 184 185 void YoungList::push_region(HeapRegion *hr) { 186 assert(!hr->is_young(), "should not already be young"); 187 assert(hr->get_next_young_region() == NULL, "cause it should!"); 188 189 hr->set_next_young_region(_head); 190 _head = hr; 191 192 _g1h->g1_policy()->set_region_eden(hr, (int) _length); 193 ++_length; 194 } 195 196 void YoungList::add_survivor_region(HeapRegion* hr) { 197 assert(hr->is_survivor(), "should be flagged as survivor region"); 198 assert(hr->get_next_young_region() == NULL, "cause it should!"); 199 200 hr->set_next_young_region(_survivor_head); 201 if (_survivor_head == NULL) { 202 _survivor_tail = hr; 203 } 204 _survivor_head = hr; 205 ++_survivor_length; 206 } 207 208 void YoungList::empty_list(HeapRegion* list) { 209 while (list != NULL) { 210 HeapRegion* next = list->get_next_young_region(); 211 list->set_next_young_region(NULL); 212 list->uninstall_surv_rate_group(); 213 list->set_not_young(); 214 list = next; 215 } 216 } 217 218 void YoungList::empty_list() { 219 assert(check_list_well_formed(), "young list should be well formed"); 220 221 empty_list(_head); 222 _head = NULL; 223 _length = 0; 224 225 empty_list(_survivor_head); 226 _survivor_head = NULL; 227 _survivor_tail = NULL; 228 _survivor_length = 0; 229 230 _last_sampled_rs_lengths = 0; 231 232 assert(check_list_empty(false), "just making sure..."); 233 } 234 235 bool YoungList::check_list_well_formed() { 236 bool ret = true; 237 238 uint length = 0; 239 HeapRegion* curr = _head; 240 HeapRegion* last = NULL; 241 while (curr != NULL) { 242 if (!curr->is_young()) { 243 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" " 244 "incorrectly tagged (y: %d, surv: %d)", 245 curr->bottom(), curr->end(), 246 curr->is_young(), curr->is_survivor()); 247 ret = false; 248 } 249 ++length; 250 last = curr; 251 curr = curr->get_next_young_region(); 252 } 253 ret = ret && (length == _length); 254 255 if (!ret) { 256 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!"); 257 gclog_or_tty->print_cr("### list has %u entries, _length is %u", 258 length, _length); 259 } 260 261 return ret; 262 } 263 264 bool YoungList::check_list_empty(bool check_sample) { 265 bool ret = true; 266 267 if (_length != 0) { 268 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u", 269 _length); 270 ret = false; 271 } 272 if (check_sample && _last_sampled_rs_lengths != 0) { 273 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths"); 274 ret = false; 275 } 276 if (_head != NULL) { 277 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head"); 278 ret = false; 279 } 280 if (!ret) { 281 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty"); 282 } 283 284 return ret; 285 } 286 287 void 288 YoungList::rs_length_sampling_init() { 289 _sampled_rs_lengths = 0; 290 _curr = _head; 291 } 292 293 bool 294 YoungList::rs_length_sampling_more() { 295 return _curr != NULL; 296 } 297 298 void 299 YoungList::rs_length_sampling_next() { 300 assert( _curr != NULL, "invariant" ); 301 size_t rs_length = _curr->rem_set()->occupied(); 302 303 _sampled_rs_lengths += rs_length; 304 305 // The current region may not yet have been added to the 306 // incremental collection set (it gets added when it is 307 // retired as the current allocation region). 308 if (_curr->in_collection_set()) { 309 // Update the collection set policy information for this region 310 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length); 311 } 312 313 _curr = _curr->get_next_young_region(); 314 if (_curr == NULL) { 315 _last_sampled_rs_lengths = _sampled_rs_lengths; 316 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths); 317 } 318 } 319 320 void 321 YoungList::reset_auxilary_lists() { 322 guarantee( is_empty(), "young list should be empty" ); 323 assert(check_list_well_formed(), "young list should be well formed"); 324 325 // Add survivor regions to SurvRateGroup. 326 _g1h->g1_policy()->note_start_adding_survivor_regions(); 327 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */); 328 329 int young_index_in_cset = 0; 330 for (HeapRegion* curr = _survivor_head; 331 curr != NULL; 332 curr = curr->get_next_young_region()) { 333 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset); 334 335 // The region is a non-empty survivor so let's add it to 336 // the incremental collection set for the next evacuation 337 // pause. 338 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr); 339 young_index_in_cset += 1; 340 } 341 assert((uint) young_index_in_cset == _survivor_length, "post-condition"); 342 _g1h->g1_policy()->note_stop_adding_survivor_regions(); 343 344 _head = _survivor_head; 345 _length = _survivor_length; 346 if (_survivor_head != NULL) { 347 assert(_survivor_tail != NULL, "cause it shouldn't be"); 348 assert(_survivor_length > 0, "invariant"); 349 _survivor_tail->set_next_young_region(NULL); 350 } 351 352 // Don't clear the survivor list handles until the start of 353 // the next evacuation pause - we need it in order to re-tag 354 // the survivor regions from this evacuation pause as 'young' 355 // at the start of the next. 356 357 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */); 358 359 assert(check_list_well_formed(), "young list should be well formed"); 360 } 361 362 void YoungList::print() { 363 HeapRegion* lists[] = {_head, _survivor_head}; 364 const char* names[] = {"YOUNG", "SURVIVOR"}; 365 366 for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) { 367 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]); 368 HeapRegion *curr = lists[list]; 369 if (curr == NULL) 370 gclog_or_tty->print_cr(" empty"); 371 while (curr != NULL) { 372 gclog_or_tty->print_cr(" "HR_FORMAT", P: "PTR_FORMAT "N: "PTR_FORMAT", age: %4d", 373 HR_FORMAT_PARAMS(curr), 374 curr->prev_top_at_mark_start(), 375 curr->next_top_at_mark_start(), 376 curr->age_in_surv_rate_group_cond()); 377 curr = curr->get_next_young_region(); 378 } 379 } 380 381 gclog_or_tty->cr(); 382 } 383 384 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr) 385 { 386 // Claim the right to put the region on the dirty cards region list 387 // by installing a self pointer. 388 HeapRegion* next = hr->get_next_dirty_cards_region(); 389 if (next == NULL) { 390 HeapRegion* res = (HeapRegion*) 391 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(), 392 NULL); 393 if (res == NULL) { 394 HeapRegion* head; 395 do { 396 // Put the region to the dirty cards region list. 397 head = _dirty_cards_region_list; 398 next = (HeapRegion*) 399 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head); 400 if (next == head) { 401 assert(hr->get_next_dirty_cards_region() == hr, 402 "hr->get_next_dirty_cards_region() != hr"); 403 if (next == NULL) { 404 // The last region in the list points to itself. 405 hr->set_next_dirty_cards_region(hr); 406 } else { 407 hr->set_next_dirty_cards_region(next); 408 } 409 } 410 } while (next != head); 411 } 412 } 413 } 414 415 HeapRegion* G1CollectedHeap::pop_dirty_cards_region() 416 { 417 HeapRegion* head; 418 HeapRegion* hr; 419 do { 420 head = _dirty_cards_region_list; 421 if (head == NULL) { 422 return NULL; 423 } 424 HeapRegion* new_head = head->get_next_dirty_cards_region(); 425 if (head == new_head) { 426 // The last region. 427 new_head = NULL; 428 } 429 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list, 430 head); 431 } while (hr != head); 432 assert(hr != NULL, "invariant"); 433 hr->set_next_dirty_cards_region(NULL); 434 return hr; 435 } 436 437 #ifdef ASSERT 438 // A region is added to the collection set as it is retired 439 // so an address p can point to a region which will be in the 440 // collection set but has not yet been retired. This method 441 // therefore is only accurate during a GC pause after all 442 // regions have been retired. It is used for debugging 443 // to check if an nmethod has references to objects that can 444 // be move during a partial collection. Though it can be 445 // inaccurate, it is sufficient for G1 because the conservative 446 // implementation of is_scavengable() for G1 will indicate that 447 // all nmethods must be scanned during a partial collection. 448 bool G1CollectedHeap::is_in_partial_collection(const void* p) { 449 if (p == NULL) { 450 return false; 451 } 452 return heap_region_containing(p)->in_collection_set(); 453 } 454 #endif 455 456 // Returns true if the reference points to an object that 457 // can move in an incremental collection. 458 bool G1CollectedHeap::is_scavengable(const void* p) { 459 HeapRegion* hr = heap_region_containing(p); 460 return !hr->isHumongous(); 461 } 462 463 void G1CollectedHeap::check_ct_logs_at_safepoint() { 464 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 465 CardTableModRefBS* ct_bs = g1_barrier_set(); 466 467 // Count the dirty cards at the start. 468 CountNonCleanMemRegionClosure count1(this); 469 ct_bs->mod_card_iterate(&count1); 470 int orig_count = count1.n(); 471 472 // First clear the logged cards. 473 ClearLoggedCardTableEntryClosure clear; 474 dcqs.apply_closure_to_all_completed_buffers(&clear); 475 dcqs.iterate_closure_all_threads(&clear, false); 476 clear.print_histo(); 477 478 // Now ensure that there's no dirty cards. 479 CountNonCleanMemRegionClosure count2(this); 480 ct_bs->mod_card_iterate(&count2); 481 if (count2.n() != 0) { 482 gclog_or_tty->print_cr("Card table has %d entries; %d originally", 483 count2.n(), orig_count); 484 } 485 guarantee(count2.n() == 0, "Card table should be clean."); 486 487 RedirtyLoggedCardTableEntryClosure redirty; 488 dcqs.apply_closure_to_all_completed_buffers(&redirty); 489 dcqs.iterate_closure_all_threads(&redirty, false); 490 gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.", 491 clear.num_processed(), orig_count); 492 guarantee(redirty.num_processed() == clear.num_processed(), 493 err_msg("Redirtied "SIZE_FORMAT" cards, bug cleared "SIZE_FORMAT, 494 redirty.num_processed(), clear.num_processed())); 495 496 CountNonCleanMemRegionClosure count3(this); 497 ct_bs->mod_card_iterate(&count3); 498 if (count3.n() != orig_count) { 499 gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.", 500 orig_count, count3.n()); 501 guarantee(count3.n() >= orig_count, "Should have restored them all."); 502 } 503 } 504 505 // Private class members. 506 507 G1CollectedHeap* G1CollectedHeap::_g1h; 508 509 // Private methods. 510 511 HeapRegion* 512 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) { 513 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 514 while (!_secondary_free_list.is_empty() || free_regions_coming()) { 515 if (!_secondary_free_list.is_empty()) { 516 if (G1ConcRegionFreeingVerbose) { 517 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 518 "secondary_free_list has %u entries", 519 _secondary_free_list.length()); 520 } 521 // It looks as if there are free regions available on the 522 // secondary_free_list. Let's move them to the free_list and try 523 // again to allocate from it. 524 append_secondary_free_list(); 525 526 assert(!_free_list.is_empty(), "if the secondary_free_list was not " 527 "empty we should have moved at least one entry to the free_list"); 528 HeapRegion* res = _free_list.remove_region(is_old); 529 if (G1ConcRegionFreeingVerbose) { 530 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 531 "allocated "HR_FORMAT" from secondary_free_list", 532 HR_FORMAT_PARAMS(res)); 533 } 534 return res; 535 } 536 537 // Wait here until we get notified either when (a) there are no 538 // more free regions coming or (b) some regions have been moved on 539 // the secondary_free_list. 540 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 541 } 542 543 if (G1ConcRegionFreeingVerbose) { 544 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 545 "could not allocate from secondary_free_list"); 546 } 547 return NULL; 548 } 549 550 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) { 551 assert(!isHumongous(word_size) || word_size <= HeapRegion::GrainWords, 552 "the only time we use this to allocate a humongous region is " 553 "when we are allocating a single humongous region"); 554 555 HeapRegion* res; 556 if (G1StressConcRegionFreeing) { 557 if (!_secondary_free_list.is_empty()) { 558 if (G1ConcRegionFreeingVerbose) { 559 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 560 "forced to look at the secondary_free_list"); 561 } 562 res = new_region_try_secondary_free_list(is_old); 563 if (res != NULL) { 564 return res; 565 } 566 } 567 } 568 569 res = _free_list.remove_region(is_old); 570 571 if (res == NULL) { 572 if (G1ConcRegionFreeingVerbose) { 573 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 574 "res == NULL, trying the secondary_free_list"); 575 } 576 res = new_region_try_secondary_free_list(is_old); 577 } 578 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) { 579 // Currently, only attempts to allocate GC alloc regions set 580 // do_expand to true. So, we should only reach here during a 581 // safepoint. If this assumption changes we might have to 582 // reconsider the use of _expand_heap_after_alloc_failure. 583 assert(SafepointSynchronize::is_at_safepoint(), "invariant"); 584 585 ergo_verbose1(ErgoHeapSizing, 586 "attempt heap expansion", 587 ergo_format_reason("region allocation request failed") 588 ergo_format_byte("allocation request"), 589 word_size * HeapWordSize); 590 if (expand(word_size * HeapWordSize)) { 591 // Given that expand() succeeded in expanding the heap, and we 592 // always expand the heap by an amount aligned to the heap 593 // region size, the free list should in theory not be empty. 594 // In either case remove_region() will check for NULL. 595 res = _free_list.remove_region(is_old); 596 } else { 597 _expand_heap_after_alloc_failure = false; 598 } 599 } 600 return res; 601 } 602 603 uint G1CollectedHeap::humongous_obj_allocate_find_first(uint num_regions, 604 size_t word_size) { 605 assert(isHumongous(word_size), "word_size should be humongous"); 606 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition"); 607 608 uint first = G1_NULL_HRS_INDEX; 609 if (num_regions == 1) { 610 // Only one region to allocate, no need to go through the slower 611 // path. The caller will attempt the expansion if this fails, so 612 // let's not try to expand here too. 613 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */); 614 if (hr != NULL) { 615 first = hr->hrs_index(); 616 } else { 617 first = G1_NULL_HRS_INDEX; 618 } 619 } else { 620 // We can't allocate humongous regions while cleanupComplete() is 621 // running, since some of the regions we find to be empty might not 622 // yet be added to the free list and it is not straightforward to 623 // know which list they are on so that we can remove them. Note 624 // that we only need to do this if we need to allocate more than 625 // one region to satisfy the current humongous allocation 626 // request. If we are only allocating one region we use the common 627 // region allocation code (see above). 628 wait_while_free_regions_coming(); 629 append_secondary_free_list_if_not_empty_with_lock(); 630 631 if (free_regions() >= num_regions) { 632 first = _hrs.find_contiguous(num_regions); 633 if (first != G1_NULL_HRS_INDEX) { 634 for (uint i = first; i < first + num_regions; ++i) { 635 HeapRegion* hr = region_at(i); 636 assert(hr->is_empty(), "sanity"); 637 assert(is_on_master_free_list(hr), "sanity"); 638 hr->set_pending_removal(true); 639 } 640 _free_list.remove_all_pending(num_regions); 641 } 642 } 643 } 644 return first; 645 } 646 647 HeapWord* 648 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first, 649 uint num_regions, 650 size_t word_size) { 651 assert(first != G1_NULL_HRS_INDEX, "pre-condition"); 652 assert(isHumongous(word_size), "word_size should be humongous"); 653 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition"); 654 655 // Index of last region in the series + 1. 656 uint last = first + num_regions; 657 658 // We need to initialize the region(s) we just discovered. This is 659 // a bit tricky given that it can happen concurrently with 660 // refinement threads refining cards on these regions and 661 // potentially wanting to refine the BOT as they are scanning 662 // those cards (this can happen shortly after a cleanup; see CR 663 // 6991377). So we have to set up the region(s) carefully and in 664 // a specific order. 665 666 // The word size sum of all the regions we will allocate. 667 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords; 668 assert(word_size <= word_size_sum, "sanity"); 669 670 // This will be the "starts humongous" region. 671 HeapRegion* first_hr = region_at(first); 672 // The header of the new object will be placed at the bottom of 673 // the first region. 674 HeapWord* new_obj = first_hr->bottom(); 675 // This will be the new end of the first region in the series that 676 // should also match the end of the last region in the series. 677 HeapWord* new_end = new_obj + word_size_sum; 678 // This will be the new top of the first region that will reflect 679 // this allocation. 680 HeapWord* new_top = new_obj + word_size; 681 682 // First, we need to zero the header of the space that we will be 683 // allocating. When we update top further down, some refinement 684 // threads might try to scan the region. By zeroing the header we 685 // ensure that any thread that will try to scan the region will 686 // come across the zero klass word and bail out. 687 // 688 // NOTE: It would not have been correct to have used 689 // CollectedHeap::fill_with_object() and make the space look like 690 // an int array. The thread that is doing the allocation will 691 // later update the object header to a potentially different array 692 // type and, for a very short period of time, the klass and length 693 // fields will be inconsistent. This could cause a refinement 694 // thread to calculate the object size incorrectly. 695 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0); 696 697 // We will set up the first region as "starts humongous". This 698 // will also update the BOT covering all the regions to reflect 699 // that there is a single object that starts at the bottom of the 700 // first region. 701 first_hr->set_startsHumongous(new_top, new_end); 702 703 // Then, if there are any, we will set up the "continues 704 // humongous" regions. 705 HeapRegion* hr = NULL; 706 for (uint i = first + 1; i < last; ++i) { 707 hr = region_at(i); 708 hr->set_continuesHumongous(first_hr); 709 } 710 // If we have "continues humongous" regions (hr != NULL), then the 711 // end of the last one should match new_end. 712 assert(hr == NULL || hr->end() == new_end, "sanity"); 713 714 // Up to this point no concurrent thread would have been able to 715 // do any scanning on any region in this series. All the top 716 // fields still point to bottom, so the intersection between 717 // [bottom,top] and [card_start,card_end] will be empty. Before we 718 // update the top fields, we'll do a storestore to make sure that 719 // no thread sees the update to top before the zeroing of the 720 // object header and the BOT initialization. 721 OrderAccess::storestore(); 722 723 // Now that the BOT and the object header have been initialized, 724 // we can update top of the "starts humongous" region. 725 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(), 726 "new_top should be in this region"); 727 first_hr->set_top(new_top); 728 if (_hr_printer.is_active()) { 729 HeapWord* bottom = first_hr->bottom(); 730 HeapWord* end = first_hr->orig_end(); 731 if ((first + 1) == last) { 732 // the series has a single humongous region 733 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top); 734 } else { 735 // the series has more than one humongous regions 736 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end); 737 } 738 } 739 740 // Now, we will update the top fields of the "continues humongous" 741 // regions. The reason we need to do this is that, otherwise, 742 // these regions would look empty and this will confuse parts of 743 // G1. For example, the code that looks for a consecutive number 744 // of empty regions will consider them empty and try to 745 // re-allocate them. We can extend is_empty() to also include 746 // !continuesHumongous(), but it is easier to just update the top 747 // fields here. The way we set top for all regions (i.e., top == 748 // end for all regions but the last one, top == new_top for the 749 // last one) is actually used when we will free up the humongous 750 // region in free_humongous_region(). 751 hr = NULL; 752 for (uint i = first + 1; i < last; ++i) { 753 hr = region_at(i); 754 if ((i + 1) == last) { 755 // last continues humongous region 756 assert(hr->bottom() < new_top && new_top <= hr->end(), 757 "new_top should fall on this region"); 758 hr->set_top(new_top); 759 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top); 760 } else { 761 // not last one 762 assert(new_top > hr->end(), "new_top should be above this region"); 763 hr->set_top(hr->end()); 764 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end()); 765 } 766 } 767 // If we have continues humongous regions (hr != NULL), then the 768 // end of the last one should match new_end and its top should 769 // match new_top. 770 assert(hr == NULL || 771 (hr->end() == new_end && hr->top() == new_top), "sanity"); 772 check_bitmaps("Humongous Region Allocation", first_hr); 773 774 assert(first_hr->used() == word_size * HeapWordSize, "invariant"); 775 _summary_bytes_used += first_hr->used(); 776 _humongous_set.add(first_hr); 777 778 return new_obj; 779 } 780 781 // If could fit into free regions w/o expansion, try. 782 // Otherwise, if can expand, do so. 783 // Otherwise, if using ex regions might help, try with ex given back. 784 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) { 785 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 786 787 verify_region_sets_optional(); 788 789 size_t word_size_rounded = round_to(word_size, HeapRegion::GrainWords); 790 uint num_regions = (uint) (word_size_rounded / HeapRegion::GrainWords); 791 uint x_num = expansion_regions(); 792 uint fs = _hrs.free_suffix(); 793 uint first = humongous_obj_allocate_find_first(num_regions, word_size); 794 if (first == G1_NULL_HRS_INDEX) { 795 // The only thing we can do now is attempt expansion. 796 if (fs + x_num >= num_regions) { 797 // If the number of regions we're trying to allocate for this 798 // object is at most the number of regions in the free suffix, 799 // then the call to humongous_obj_allocate_find_first() above 800 // should have succeeded and we wouldn't be here. 801 // 802 // We should only be trying to expand when the free suffix is 803 // not sufficient for the object _and_ we have some expansion 804 // room available. 805 assert(num_regions > fs, "earlier allocation should have succeeded"); 806 807 ergo_verbose1(ErgoHeapSizing, 808 "attempt heap expansion", 809 ergo_format_reason("humongous allocation request failed") 810 ergo_format_byte("allocation request"), 811 word_size * HeapWordSize); 812 if (expand((num_regions - fs) * HeapRegion::GrainBytes)) { 813 // Even though the heap was expanded, it might not have 814 // reached the desired size. So, we cannot assume that the 815 // allocation will succeed. 816 first = humongous_obj_allocate_find_first(num_regions, word_size); 817 } 818 } 819 } 820 821 HeapWord* result = NULL; 822 if (first != G1_NULL_HRS_INDEX) { 823 result = 824 humongous_obj_allocate_initialize_regions(first, num_regions, word_size); 825 assert(result != NULL, "it should always return a valid result"); 826 827 // A successful humongous object allocation changes the used space 828 // information of the old generation so we need to recalculate the 829 // sizes and update the jstat counters here. 830 g1mm()->update_sizes(); 831 } 832 833 verify_region_sets_optional(); 834 835 return result; 836 } 837 838 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) { 839 assert_heap_not_locked_and_not_at_safepoint(); 840 assert(!isHumongous(word_size), "we do not allow humongous TLABs"); 841 842 unsigned int dummy_gc_count_before; 843 int dummy_gclocker_retry_count = 0; 844 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count); 845 } 846 847 HeapWord* 848 G1CollectedHeap::mem_allocate(size_t word_size, 849 bool* gc_overhead_limit_was_exceeded) { 850 assert_heap_not_locked_and_not_at_safepoint(); 851 852 // Loop until the allocation is satisfied, or unsatisfied after GC. 853 for (int try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 854 unsigned int gc_count_before; 855 856 HeapWord* result = NULL; 857 if (!isHumongous(word_size)) { 858 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count); 859 } else { 860 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count); 861 } 862 if (result != NULL) { 863 return result; 864 } 865 866 // Create the garbage collection operation... 867 VM_G1CollectForAllocation op(gc_count_before, word_size); 868 // ...and get the VM thread to execute it. 869 VMThread::execute(&op); 870 871 if (op.prologue_succeeded() && op.pause_succeeded()) { 872 // If the operation was successful we'll return the result even 873 // if it is NULL. If the allocation attempt failed immediately 874 // after a Full GC, it's unlikely we'll be able to allocate now. 875 HeapWord* result = op.result(); 876 if (result != NULL && !isHumongous(word_size)) { 877 // Allocations that take place on VM operations do not do any 878 // card dirtying and we have to do it here. We only have to do 879 // this for non-humongous allocations, though. 880 dirty_young_block(result, word_size); 881 } 882 return result; 883 } else { 884 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 885 return NULL; 886 } 887 assert(op.result() == NULL, 888 "the result should be NULL if the VM op did not succeed"); 889 } 890 891 // Give a warning if we seem to be looping forever. 892 if ((QueuedAllocationWarningCount > 0) && 893 (try_count % QueuedAllocationWarningCount == 0)) { 894 warning("G1CollectedHeap::mem_allocate retries %d times", try_count); 895 } 896 } 897 898 ShouldNotReachHere(); 899 return NULL; 900 } 901 902 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size, 903 unsigned int *gc_count_before_ret, 904 int* gclocker_retry_count_ret) { 905 // Make sure you read the note in attempt_allocation_humongous(). 906 907 assert_heap_not_locked_and_not_at_safepoint(); 908 assert(!isHumongous(word_size), "attempt_allocation_slow() should not " 909 "be called for humongous allocation requests"); 910 911 // We should only get here after the first-level allocation attempt 912 // (attempt_allocation()) failed to allocate. 913 914 // We will loop until a) we manage to successfully perform the 915 // allocation or b) we successfully schedule a collection which 916 // fails to perform the allocation. b) is the only case when we'll 917 // return NULL. 918 HeapWord* result = NULL; 919 for (int try_count = 1; /* we'll return */; try_count += 1) { 920 bool should_try_gc; 921 unsigned int gc_count_before; 922 923 { 924 MutexLockerEx x(Heap_lock); 925 926 result = _mutator_alloc_region.attempt_allocation_locked(word_size, 927 false /* bot_updates */); 928 if (result != NULL) { 929 return result; 930 } 931 932 // If we reach here, attempt_allocation_locked() above failed to 933 // allocate a new region. So the mutator alloc region should be NULL. 934 assert(_mutator_alloc_region.get() == NULL, "only way to get here"); 935 936 if (GC_locker::is_active_and_needs_gc()) { 937 if (g1_policy()->can_expand_young_list()) { 938 // No need for an ergo verbose message here, 939 // can_expand_young_list() does this when it returns true. 940 result = _mutator_alloc_region.attempt_allocation_force(word_size, 941 false /* bot_updates */); 942 if (result != NULL) { 943 return result; 944 } 945 } 946 should_try_gc = false; 947 } else { 948 // The GCLocker may not be active but the GCLocker initiated 949 // GC may not yet have been performed (GCLocker::needs_gc() 950 // returns true). In this case we do not try this GC and 951 // wait until the GCLocker initiated GC is performed, and 952 // then retry the allocation. 953 if (GC_locker::needs_gc()) { 954 should_try_gc = false; 955 } else { 956 // Read the GC count while still holding the Heap_lock. 957 gc_count_before = total_collections(); 958 should_try_gc = true; 959 } 960 } 961 } 962 963 if (should_try_gc) { 964 bool succeeded; 965 result = do_collection_pause(word_size, gc_count_before, &succeeded, 966 GCCause::_g1_inc_collection_pause); 967 if (result != NULL) { 968 assert(succeeded, "only way to get back a non-NULL result"); 969 return result; 970 } 971 972 if (succeeded) { 973 // If we get here we successfully scheduled a collection which 974 // failed to allocate. No point in trying to allocate 975 // further. We'll just return NULL. 976 MutexLockerEx x(Heap_lock); 977 *gc_count_before_ret = total_collections(); 978 return NULL; 979 } 980 } else { 981 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { 982 MutexLockerEx x(Heap_lock); 983 *gc_count_before_ret = total_collections(); 984 return NULL; 985 } 986 // The GCLocker is either active or the GCLocker initiated 987 // GC has not yet been performed. Stall until it is and 988 // then retry the allocation. 989 GC_locker::stall_until_clear(); 990 (*gclocker_retry_count_ret) += 1; 991 } 992 993 // We can reach here if we were unsuccessful in scheduling a 994 // collection (because another thread beat us to it) or if we were 995 // stalled due to the GC locker. In either can we should retry the 996 // allocation attempt in case another thread successfully 997 // performed a collection and reclaimed enough space. We do the 998 // first attempt (without holding the Heap_lock) here and the 999 // follow-on attempt will be at the start of the next loop 1000 // iteration (after taking the Heap_lock). 1001 result = _mutator_alloc_region.attempt_allocation(word_size, 1002 false /* bot_updates */); 1003 if (result != NULL) { 1004 return result; 1005 } 1006 1007 // Give a warning if we seem to be looping forever. 1008 if ((QueuedAllocationWarningCount > 0) && 1009 (try_count % QueuedAllocationWarningCount == 0)) { 1010 warning("G1CollectedHeap::attempt_allocation_slow() " 1011 "retries %d times", try_count); 1012 } 1013 } 1014 1015 ShouldNotReachHere(); 1016 return NULL; 1017 } 1018 1019 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size, 1020 unsigned int * gc_count_before_ret, 1021 int* gclocker_retry_count_ret) { 1022 // The structure of this method has a lot of similarities to 1023 // attempt_allocation_slow(). The reason these two were not merged 1024 // into a single one is that such a method would require several "if 1025 // allocation is not humongous do this, otherwise do that" 1026 // conditional paths which would obscure its flow. In fact, an early 1027 // version of this code did use a unified method which was harder to 1028 // follow and, as a result, it had subtle bugs that were hard to 1029 // track down. So keeping these two methods separate allows each to 1030 // be more readable. It will be good to keep these two in sync as 1031 // much as possible. 1032 1033 assert_heap_not_locked_and_not_at_safepoint(); 1034 assert(isHumongous(word_size), "attempt_allocation_humongous() " 1035 "should only be called for humongous allocations"); 1036 1037 // Humongous objects can exhaust the heap quickly, so we should check if we 1038 // need to start a marking cycle at each humongous object allocation. We do 1039 // the check before we do the actual allocation. The reason for doing it 1040 // before the allocation is that we avoid having to keep track of the newly 1041 // allocated memory while we do a GC. 1042 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation", 1043 word_size)) { 1044 collect(GCCause::_g1_humongous_allocation); 1045 } 1046 1047 // We will loop until a) we manage to successfully perform the 1048 // allocation or b) we successfully schedule a collection which 1049 // fails to perform the allocation. b) is the only case when we'll 1050 // return NULL. 1051 HeapWord* result = NULL; 1052 for (int try_count = 1; /* we'll return */; try_count += 1) { 1053 bool should_try_gc; 1054 unsigned int gc_count_before; 1055 1056 { 1057 MutexLockerEx x(Heap_lock); 1058 1059 // Given that humongous objects are not allocated in young 1060 // regions, we'll first try to do the allocation without doing a 1061 // collection hoping that there's enough space in the heap. 1062 result = humongous_obj_allocate(word_size); 1063 if (result != NULL) { 1064 return result; 1065 } 1066 1067 if (GC_locker::is_active_and_needs_gc()) { 1068 should_try_gc = false; 1069 } else { 1070 // The GCLocker may not be active but the GCLocker initiated 1071 // GC may not yet have been performed (GCLocker::needs_gc() 1072 // returns true). In this case we do not try this GC and 1073 // wait until the GCLocker initiated GC is performed, and 1074 // then retry the allocation. 1075 if (GC_locker::needs_gc()) { 1076 should_try_gc = false; 1077 } else { 1078 // Read the GC count while still holding the Heap_lock. 1079 gc_count_before = total_collections(); 1080 should_try_gc = true; 1081 } 1082 } 1083 } 1084 1085 if (should_try_gc) { 1086 // If we failed to allocate the humongous object, we should try to 1087 // do a collection pause (if we're allowed) in case it reclaims 1088 // enough space for the allocation to succeed after the pause. 1089 1090 bool succeeded; 1091 result = do_collection_pause(word_size, gc_count_before, &succeeded, 1092 GCCause::_g1_humongous_allocation); 1093 if (result != NULL) { 1094 assert(succeeded, "only way to get back a non-NULL result"); 1095 return result; 1096 } 1097 1098 if (succeeded) { 1099 // If we get here we successfully scheduled a collection which 1100 // failed to allocate. No point in trying to allocate 1101 // further. We'll just return NULL. 1102 MutexLockerEx x(Heap_lock); 1103 *gc_count_before_ret = total_collections(); 1104 return NULL; 1105 } 1106 } else { 1107 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { 1108 MutexLockerEx x(Heap_lock); 1109 *gc_count_before_ret = total_collections(); 1110 return NULL; 1111 } 1112 // The GCLocker is either active or the GCLocker initiated 1113 // GC has not yet been performed. Stall until it is and 1114 // then retry the allocation. 1115 GC_locker::stall_until_clear(); 1116 (*gclocker_retry_count_ret) += 1; 1117 } 1118 1119 // We can reach here if we were unsuccessful in scheduling a 1120 // collection (because another thread beat us to it) or if we were 1121 // stalled due to the GC locker. In either can we should retry the 1122 // allocation attempt in case another thread successfully 1123 // performed a collection and reclaimed enough space. Give a 1124 // warning if we seem to be looping forever. 1125 1126 if ((QueuedAllocationWarningCount > 0) && 1127 (try_count % QueuedAllocationWarningCount == 0)) { 1128 warning("G1CollectedHeap::attempt_allocation_humongous() " 1129 "retries %d times", try_count); 1130 } 1131 } 1132 1133 ShouldNotReachHere(); 1134 return NULL; 1135 } 1136 1137 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size, 1138 bool expect_null_mutator_alloc_region) { 1139 assert_at_safepoint(true /* should_be_vm_thread */); 1140 assert(_mutator_alloc_region.get() == NULL || 1141 !expect_null_mutator_alloc_region, 1142 "the current alloc region was unexpectedly found to be non-NULL"); 1143 1144 if (!isHumongous(word_size)) { 1145 return _mutator_alloc_region.attempt_allocation_locked(word_size, 1146 false /* bot_updates */); 1147 } else { 1148 HeapWord* result = humongous_obj_allocate(word_size); 1149 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) { 1150 g1_policy()->set_initiate_conc_mark_if_possible(); 1151 } 1152 return result; 1153 } 1154 1155 ShouldNotReachHere(); 1156 } 1157 1158 class PostMCRemSetClearClosure: public HeapRegionClosure { 1159 G1CollectedHeap* _g1h; 1160 ModRefBarrierSet* _mr_bs; 1161 public: 1162 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) : 1163 _g1h(g1h), _mr_bs(mr_bs) {} 1164 1165 bool doHeapRegion(HeapRegion* r) { 1166 HeapRegionRemSet* hrrs = r->rem_set(); 1167 1168 if (r->continuesHumongous()) { 1169 // We'll assert that the strong code root list and RSet is empty 1170 assert(hrrs->strong_code_roots_list_length() == 0, "sanity"); 1171 assert(hrrs->occupied() == 0, "RSet should be empty"); 1172 return false; 1173 } 1174 1175 _g1h->reset_gc_time_stamps(r); 1176 hrrs->clear(); 1177 // You might think here that we could clear just the cards 1178 // corresponding to the used region. But no: if we leave a dirty card 1179 // in a region we might allocate into, then it would prevent that card 1180 // from being enqueued, and cause it to be missed. 1181 // Re: the performance cost: we shouldn't be doing full GC anyway! 1182 _mr_bs->clear(MemRegion(r->bottom(), r->end())); 1183 1184 return false; 1185 } 1186 }; 1187 1188 void G1CollectedHeap::clear_rsets_post_compaction() { 1189 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set()); 1190 heap_region_iterate(&rs_clear); 1191 } 1192 1193 class RebuildRSOutOfRegionClosure: public HeapRegionClosure { 1194 G1CollectedHeap* _g1h; 1195 UpdateRSOopClosure _cl; 1196 int _worker_i; 1197 public: 1198 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) : 1199 _cl(g1->g1_rem_set(), worker_i), 1200 _worker_i(worker_i), 1201 _g1h(g1) 1202 { } 1203 1204 bool doHeapRegion(HeapRegion* r) { 1205 if (!r->continuesHumongous()) { 1206 _cl.set_from(r); 1207 r->oop_iterate(&_cl); 1208 } 1209 return false; 1210 } 1211 }; 1212 1213 class ParRebuildRSTask: public AbstractGangTask { 1214 G1CollectedHeap* _g1; 1215 public: 1216 ParRebuildRSTask(G1CollectedHeap* g1) 1217 : AbstractGangTask("ParRebuildRSTask"), 1218 _g1(g1) 1219 { } 1220 1221 void work(uint worker_id) { 1222 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id); 1223 _g1->heap_region_par_iterate_chunked(&rebuild_rs, worker_id, 1224 _g1->workers()->active_workers(), 1225 HeapRegion::RebuildRSClaimValue); 1226 } 1227 }; 1228 1229 class PostCompactionPrinterClosure: public HeapRegionClosure { 1230 private: 1231 G1HRPrinter* _hr_printer; 1232 public: 1233 bool doHeapRegion(HeapRegion* hr) { 1234 assert(!hr->is_young(), "not expecting to find young regions"); 1235 // We only generate output for non-empty regions. 1236 if (!hr->is_empty()) { 1237 if (!hr->isHumongous()) { 1238 _hr_printer->post_compaction(hr, G1HRPrinter::Old); 1239 } else if (hr->startsHumongous()) { 1240 if (hr->region_num() == 1) { 1241 // single humongous region 1242 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous); 1243 } else { 1244 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous); 1245 } 1246 } else { 1247 assert(hr->continuesHumongous(), "only way to get here"); 1248 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous); 1249 } 1250 } 1251 return false; 1252 } 1253 1254 PostCompactionPrinterClosure(G1HRPrinter* hr_printer) 1255 : _hr_printer(hr_printer) { } 1256 }; 1257 1258 void G1CollectedHeap::print_hrs_post_compaction() { 1259 PostCompactionPrinterClosure cl(hr_printer()); 1260 heap_region_iterate(&cl); 1261 } 1262 1263 bool G1CollectedHeap::do_collection(bool explicit_gc, 1264 bool clear_all_soft_refs, 1265 size_t word_size) { 1266 assert_at_safepoint(true /* should_be_vm_thread */); 1267 1268 if (GC_locker::check_active_before_gc()) { 1269 return false; 1270 } 1271 1272 STWGCTimer* gc_timer = G1MarkSweep::gc_timer(); 1273 gc_timer->register_gc_start(); 1274 1275 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer(); 1276 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start()); 1277 1278 SvcGCMarker sgcm(SvcGCMarker::FULL); 1279 ResourceMark rm; 1280 1281 print_heap_before_gc(); 1282 trace_heap_before_gc(gc_tracer); 1283 1284 size_t metadata_prev_used = MetaspaceAux::used_bytes(); 1285 1286 verify_region_sets_optional(); 1287 1288 const bool do_clear_all_soft_refs = clear_all_soft_refs || 1289 collector_policy()->should_clear_all_soft_refs(); 1290 1291 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy()); 1292 1293 { 1294 IsGCActiveMark x; 1295 1296 // Timing 1297 assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant"); 1298 gclog_or_tty->date_stamp(G1Log::fine() && PrintGCDateStamps); 1299 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty); 1300 1301 { 1302 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL, gc_tracer->gc_id()); 1303 TraceCollectorStats tcs(g1mm()->full_collection_counters()); 1304 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause()); 1305 1306 double start = os::elapsedTime(); 1307 g1_policy()->record_full_collection_start(); 1308 1309 // Note: When we have a more flexible GC logging framework that 1310 // allows us to add optional attributes to a GC log record we 1311 // could consider timing and reporting how long we wait in the 1312 // following two methods. 1313 wait_while_free_regions_coming(); 1314 // If we start the compaction before the CM threads finish 1315 // scanning the root regions we might trip them over as we'll 1316 // be moving objects / updating references. So let's wait until 1317 // they are done. By telling them to abort, they should complete 1318 // early. 1319 _cm->root_regions()->abort(); 1320 _cm->root_regions()->wait_until_scan_finished(); 1321 append_secondary_free_list_if_not_empty_with_lock(); 1322 1323 gc_prologue(true); 1324 increment_total_collections(true /* full gc */); 1325 increment_old_marking_cycles_started(); 1326 1327 assert(used() == recalculate_used(), "Should be equal"); 1328 1329 verify_before_gc(); 1330 1331 check_bitmaps("Full GC Start"); 1332 pre_full_gc_dump(gc_timer); 1333 1334 COMPILER2_PRESENT(DerivedPointerTable::clear()); 1335 1336 // Disable discovery and empty the discovered lists 1337 // for the CM ref processor. 1338 ref_processor_cm()->disable_discovery(); 1339 ref_processor_cm()->abandon_partial_discovery(); 1340 ref_processor_cm()->verify_no_references_recorded(); 1341 1342 // Abandon current iterations of concurrent marking and concurrent 1343 // refinement, if any are in progress. We have to do this before 1344 // wait_until_scan_finished() below. 1345 concurrent_mark()->abort(); 1346 1347 // Make sure we'll choose a new allocation region afterwards. 1348 release_mutator_alloc_region(); 1349 abandon_gc_alloc_regions(); 1350 g1_rem_set()->cleanupHRRS(); 1351 1352 // We should call this after we retire any currently active alloc 1353 // regions so that all the ALLOC / RETIRE events are generated 1354 // before the start GC event. 1355 _hr_printer.start_gc(true /* full */, (size_t) total_collections()); 1356 1357 // We may have added regions to the current incremental collection 1358 // set between the last GC or pause and now. We need to clear the 1359 // incremental collection set and then start rebuilding it afresh 1360 // after this full GC. 1361 abandon_collection_set(g1_policy()->inc_cset_head()); 1362 g1_policy()->clear_incremental_cset(); 1363 g1_policy()->stop_incremental_cset_building(); 1364 1365 tear_down_region_sets(false /* free_list_only */); 1366 g1_policy()->set_gcs_are_young(true); 1367 1368 // See the comments in g1CollectedHeap.hpp and 1369 // G1CollectedHeap::ref_processing_init() about 1370 // how reference processing currently works in G1. 1371 1372 // Temporarily make discovery by the STW ref processor single threaded (non-MT). 1373 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false); 1374 1375 // Temporarily clear the STW ref processor's _is_alive_non_header field. 1376 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL); 1377 1378 ref_processor_stw()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/); 1379 ref_processor_stw()->setup_policy(do_clear_all_soft_refs); 1380 1381 // Do collection work 1382 { 1383 HandleMark hm; // Discard invalid handles created during gc 1384 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs); 1385 } 1386 1387 assert(free_regions() == 0, "we should not have added any free regions"); 1388 rebuild_region_sets(false /* free_list_only */); 1389 1390 // Enqueue any discovered reference objects that have 1391 // not been removed from the discovered lists. 1392 ref_processor_stw()->enqueue_discovered_references(); 1393 1394 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 1395 1396 MemoryService::track_memory_usage(); 1397 1398 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 1399 ref_processor_stw()->verify_no_references_recorded(); 1400 1401 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 1402 ClassLoaderDataGraph::purge(); 1403 MetaspaceAux::verify_metrics(); 1404 1405 // Note: since we've just done a full GC, concurrent 1406 // marking is no longer active. Therefore we need not 1407 // re-enable reference discovery for the CM ref processor. 1408 // That will be done at the start of the next marking cycle. 1409 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition"); 1410 ref_processor_cm()->verify_no_references_recorded(); 1411 1412 reset_gc_time_stamp(); 1413 // Since everything potentially moved, we will clear all remembered 1414 // sets, and clear all cards. Later we will rebuild remembered 1415 // sets. We will also reset the GC time stamps of the regions. 1416 clear_rsets_post_compaction(); 1417 check_gc_time_stamps(); 1418 1419 // Resize the heap if necessary. 1420 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size); 1421 1422 if (_hr_printer.is_active()) { 1423 // We should do this after we potentially resize the heap so 1424 // that all the COMMIT / UNCOMMIT events are generated before 1425 // the end GC event. 1426 1427 print_hrs_post_compaction(); 1428 _hr_printer.end_gc(true /* full */, (size_t) total_collections()); 1429 } 1430 1431 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 1432 if (hot_card_cache->use_cache()) { 1433 hot_card_cache->reset_card_counts(); 1434 hot_card_cache->reset_hot_cache(); 1435 } 1436 1437 // Rebuild remembered sets of all regions. 1438 if (G1CollectedHeap::use_parallel_gc_threads()) { 1439 uint n_workers = 1440 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 1441 workers()->active_workers(), 1442 Threads::number_of_non_daemon_threads()); 1443 assert(UseDynamicNumberOfGCThreads || 1444 n_workers == workers()->total_workers(), 1445 "If not dynamic should be using all the workers"); 1446 workers()->set_active_workers(n_workers); 1447 // Set parallel threads in the heap (_n_par_threads) only 1448 // before a parallel phase and always reset it to 0 after 1449 // the phase so that the number of parallel threads does 1450 // no get carried forward to a serial phase where there 1451 // may be code that is "possibly_parallel". 1452 set_par_threads(n_workers); 1453 1454 ParRebuildRSTask rebuild_rs_task(this); 1455 assert(check_heap_region_claim_values( 1456 HeapRegion::InitialClaimValue), "sanity check"); 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 assert(check_heap_region_claim_values( 1467 HeapRegion::RebuildRSClaimValue), "sanity check"); 1468 reset_heap_region_claim_values(); 1469 } else { 1470 RebuildRSOutOfRegionClosure rebuild_rs(this); 1471 heap_region_iterate(&rebuild_rs); 1472 } 1473 1474 // Rebuild the strong code root lists for each region 1475 rebuild_strong_code_roots(); 1476 1477 if (true) { // FIXME 1478 MetaspaceGC::compute_new_size(); 1479 } 1480 1481 #ifdef TRACESPINNING 1482 ParallelTaskTerminator::print_termination_counts(); 1483 #endif 1484 1485 // Discard all rset updates 1486 JavaThread::dirty_card_queue_set().abandon_logs(); 1487 assert(!G1DeferredRSUpdate 1488 || (G1DeferredRSUpdate && 1489 (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any"); 1490 1491 _young_list->reset_sampled_info(); 1492 // At this point there should be no regions in the 1493 // entire heap tagged as young. 1494 assert(check_young_list_empty(true /* check_heap */), 1495 "young list should be empty at this point"); 1496 1497 // Update the number of full collections that have been completed. 1498 increment_old_marking_cycles_completed(false /* concurrent */); 1499 1500 _hrs.verify_optional(); 1501 verify_region_sets_optional(); 1502 1503 verify_after_gc(); 1504 1505 // Clear the previous marking bitmap, if needed for bitmap verification. 1506 // Note we cannot do this when we clear the next marking bitmap in 1507 // ConcurrentMark::abort() above since VerifyDuringGC verifies the 1508 // objects marked during a full GC against the previous bitmap. 1509 // But we need to clear it before calling check_bitmaps below since 1510 // the full GC has compacted objects and updated TAMS but not updated 1511 // the prev bitmap. 1512 if (G1VerifyBitmaps) { 1513 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll(); 1514 } 1515 check_bitmaps("Full GC End"); 1516 1517 // Start a new incremental collection set for the next pause 1518 assert(g1_policy()->collection_set() == NULL, "must be"); 1519 g1_policy()->start_incremental_cset_building(); 1520 1521 clear_cset_fast_test(); 1522 1523 init_mutator_alloc_region(); 1524 1525 double end = os::elapsedTime(); 1526 g1_policy()->record_full_collection_end(); 1527 1528 if (G1Log::fine()) { 1529 g1_policy()->print_heap_transition(); 1530 } 1531 1532 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 1533 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 1534 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 1535 // before any GC notifications are raised. 1536 g1mm()->update_sizes(); 1537 1538 gc_epilogue(true); 1539 } 1540 1541 if (G1Log::finer()) { 1542 g1_policy()->print_detailed_heap_transition(true /* full */); 1543 } 1544 1545 print_heap_after_gc(); 1546 trace_heap_after_gc(gc_tracer); 1547 1548 post_full_gc_dump(gc_timer); 1549 1550 gc_timer->register_gc_end(); 1551 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions()); 1552 } 1553 1554 return true; 1555 } 1556 1557 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) { 1558 // do_collection() will return whether it succeeded in performing 1559 // the GC. Currently, there is no facility on the 1560 // do_full_collection() API to notify the caller than the collection 1561 // did not succeed (e.g., because it was locked out by the GC 1562 // locker). So, right now, we'll ignore the return value. 1563 bool dummy = do_collection(true, /* explicit_gc */ 1564 clear_all_soft_refs, 1565 0 /* word_size */); 1566 } 1567 1568 // This code is mostly copied from TenuredGeneration. 1569 void 1570 G1CollectedHeap:: 1571 resize_if_necessary_after_full_collection(size_t word_size) { 1572 // Include the current allocation, if any, and bytes that will be 1573 // pre-allocated to support collections, as "used". 1574 const size_t used_after_gc = used(); 1575 const size_t capacity_after_gc = capacity(); 1576 const size_t free_after_gc = capacity_after_gc - used_after_gc; 1577 1578 // This is enforced in arguments.cpp. 1579 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, 1580 "otherwise the code below doesn't make sense"); 1581 1582 // We don't have floating point command-line arguments 1583 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0; 1584 const double maximum_used_percentage = 1.0 - minimum_free_percentage; 1585 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0; 1586 const double minimum_used_percentage = 1.0 - maximum_free_percentage; 1587 1588 const size_t min_heap_size = collector_policy()->min_heap_byte_size(); 1589 const size_t max_heap_size = collector_policy()->max_heap_byte_size(); 1590 1591 // We have to be careful here as these two calculations can overflow 1592 // 32-bit size_t's. 1593 double used_after_gc_d = (double) used_after_gc; 1594 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage; 1595 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage; 1596 1597 // Let's make sure that they are both under the max heap size, which 1598 // by default will make them fit into a size_t. 1599 double desired_capacity_upper_bound = (double) max_heap_size; 1600 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d, 1601 desired_capacity_upper_bound); 1602 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d, 1603 desired_capacity_upper_bound); 1604 1605 // We can now safely turn them into size_t's. 1606 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d; 1607 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d; 1608 1609 // This assert only makes sense here, before we adjust them 1610 // with respect to the min and max heap size. 1611 assert(minimum_desired_capacity <= maximum_desired_capacity, 1612 err_msg("minimum_desired_capacity = "SIZE_FORMAT", " 1613 "maximum_desired_capacity = "SIZE_FORMAT, 1614 minimum_desired_capacity, maximum_desired_capacity)); 1615 1616 // Should not be greater than the heap max size. No need to adjust 1617 // it with respect to the heap min size as it's a lower bound (i.e., 1618 // we'll try to make the capacity larger than it, not smaller). 1619 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size); 1620 // Should not be less than the heap min size. No need to adjust it 1621 // with respect to the heap max size as it's an upper bound (i.e., 1622 // we'll try to make the capacity smaller than it, not greater). 1623 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size); 1624 1625 if (capacity_after_gc < minimum_desired_capacity) { 1626 // Don't expand unless it's significant 1627 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc; 1628 ergo_verbose4(ErgoHeapSizing, 1629 "attempt heap expansion", 1630 ergo_format_reason("capacity lower than " 1631 "min desired capacity after Full GC") 1632 ergo_format_byte("capacity") 1633 ergo_format_byte("occupancy") 1634 ergo_format_byte_perc("min desired capacity"), 1635 capacity_after_gc, used_after_gc, 1636 minimum_desired_capacity, (double) MinHeapFreeRatio); 1637 expand(expand_bytes); 1638 1639 // No expansion, now see if we want to shrink 1640 } else if (capacity_after_gc > maximum_desired_capacity) { 1641 // Capacity too large, compute shrinking size 1642 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity; 1643 ergo_verbose4(ErgoHeapSizing, 1644 "attempt heap shrinking", 1645 ergo_format_reason("capacity higher than " 1646 "max desired capacity after Full GC") 1647 ergo_format_byte("capacity") 1648 ergo_format_byte("occupancy") 1649 ergo_format_byte_perc("max desired capacity"), 1650 capacity_after_gc, used_after_gc, 1651 maximum_desired_capacity, (double) MaxHeapFreeRatio); 1652 shrink(shrink_bytes); 1653 } 1654 } 1655 1656 1657 HeapWord* 1658 G1CollectedHeap::satisfy_failed_allocation(size_t word_size, 1659 bool* succeeded) { 1660 assert_at_safepoint(true /* should_be_vm_thread */); 1661 1662 *succeeded = true; 1663 // Let's attempt the allocation first. 1664 HeapWord* result = 1665 attempt_allocation_at_safepoint(word_size, 1666 false /* expect_null_mutator_alloc_region */); 1667 if (result != NULL) { 1668 assert(*succeeded, "sanity"); 1669 return result; 1670 } 1671 1672 // In a G1 heap, we're supposed to keep allocation from failing by 1673 // incremental pauses. Therefore, at least for now, we'll favor 1674 // expansion over collection. (This might change in the future if we can 1675 // do something smarter than full collection to satisfy a failed alloc.) 1676 result = expand_and_allocate(word_size); 1677 if (result != NULL) { 1678 assert(*succeeded, "sanity"); 1679 return result; 1680 } 1681 1682 // Expansion didn't work, we'll try to do a Full GC. 1683 bool gc_succeeded = do_collection(false, /* explicit_gc */ 1684 false, /* clear_all_soft_refs */ 1685 word_size); 1686 if (!gc_succeeded) { 1687 *succeeded = false; 1688 return NULL; 1689 } 1690 1691 // Retry the allocation 1692 result = attempt_allocation_at_safepoint(word_size, 1693 true /* expect_null_mutator_alloc_region */); 1694 if (result != NULL) { 1695 assert(*succeeded, "sanity"); 1696 return result; 1697 } 1698 1699 // Then, try a Full GC that will collect all soft references. 1700 gc_succeeded = do_collection(false, /* explicit_gc */ 1701 true, /* clear_all_soft_refs */ 1702 word_size); 1703 if (!gc_succeeded) { 1704 *succeeded = false; 1705 return NULL; 1706 } 1707 1708 // Retry the allocation once more 1709 result = attempt_allocation_at_safepoint(word_size, 1710 true /* expect_null_mutator_alloc_region */); 1711 if (result != NULL) { 1712 assert(*succeeded, "sanity"); 1713 return result; 1714 } 1715 1716 assert(!collector_policy()->should_clear_all_soft_refs(), 1717 "Flag should have been handled and cleared prior to this point"); 1718 1719 // What else? We might try synchronous finalization later. If the total 1720 // space available is large enough for the allocation, then a more 1721 // complete compaction phase than we've tried so far might be 1722 // appropriate. 1723 assert(*succeeded, "sanity"); 1724 return NULL; 1725 } 1726 1727 // Attempting to expand the heap sufficiently 1728 // to support an allocation of the given "word_size". If 1729 // successful, perform the allocation and return the address of the 1730 // allocated block, or else "NULL". 1731 1732 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) { 1733 assert_at_safepoint(true /* should_be_vm_thread */); 1734 1735 verify_region_sets_optional(); 1736 1737 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes); 1738 ergo_verbose1(ErgoHeapSizing, 1739 "attempt heap expansion", 1740 ergo_format_reason("allocation request failed") 1741 ergo_format_byte("allocation request"), 1742 word_size * HeapWordSize); 1743 if (expand(expand_bytes)) { 1744 _hrs.verify_optional(); 1745 verify_region_sets_optional(); 1746 return attempt_allocation_at_safepoint(word_size, 1747 false /* expect_null_mutator_alloc_region */); 1748 } 1749 return NULL; 1750 } 1751 1752 void G1CollectedHeap::update_committed_space(HeapWord* old_end, 1753 HeapWord* new_end) { 1754 assert(old_end != new_end, "don't call this otherwise"); 1755 assert((HeapWord*) _g1_storage.high() == new_end, "invariant"); 1756 1757 // Update the committed mem region. 1758 _g1_committed.set_end(new_end); 1759 // Tell the card table about the update. 1760 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed); 1761 // Tell the BOT about the update. 1762 _bot_shared->resize(_g1_committed.word_size()); 1763 // Tell the hot card cache about the update 1764 _cg1r->hot_card_cache()->resize_card_counts(capacity()); 1765 } 1766 1767 bool G1CollectedHeap::expand(size_t expand_bytes) { 1768 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); 1769 aligned_expand_bytes = align_size_up(aligned_expand_bytes, 1770 HeapRegion::GrainBytes); 1771 ergo_verbose2(ErgoHeapSizing, 1772 "expand the heap", 1773 ergo_format_byte("requested expansion amount") 1774 ergo_format_byte("attempted expansion amount"), 1775 expand_bytes, aligned_expand_bytes); 1776 1777 if (_g1_storage.uncommitted_size() == 0) { 1778 ergo_verbose0(ErgoHeapSizing, 1779 "did not expand the heap", 1780 ergo_format_reason("heap already fully expanded")); 1781 return false; 1782 } 1783 1784 // First commit the memory. 1785 HeapWord* old_end = (HeapWord*) _g1_storage.high(); 1786 bool successful = _g1_storage.expand_by(aligned_expand_bytes); 1787 if (successful) { 1788 // Then propagate this update to the necessary data structures. 1789 HeapWord* new_end = (HeapWord*) _g1_storage.high(); 1790 update_committed_space(old_end, new_end); 1791 1792 FreeRegionList expansion_list("Local Expansion List"); 1793 MemRegion mr = _hrs.expand_by(old_end, new_end, &expansion_list); 1794 assert(mr.start() == old_end, "post-condition"); 1795 // mr might be a smaller region than what was requested if 1796 // expand_by() was unable to allocate the HeapRegion instances 1797 assert(mr.end() <= new_end, "post-condition"); 1798 1799 size_t actual_expand_bytes = mr.byte_size(); 1800 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition"); 1801 assert(actual_expand_bytes == expansion_list.total_capacity_bytes(), 1802 "post-condition"); 1803 if (actual_expand_bytes < aligned_expand_bytes) { 1804 // We could not expand _hrs to the desired size. In this case we 1805 // need to shrink the committed space accordingly. 1806 assert(mr.end() < new_end, "invariant"); 1807 1808 size_t diff_bytes = aligned_expand_bytes - actual_expand_bytes; 1809 // First uncommit the memory. 1810 _g1_storage.shrink_by(diff_bytes); 1811 // Then propagate this update to the necessary data structures. 1812 update_committed_space(new_end, mr.end()); 1813 } 1814 _free_list.add_as_tail(&expansion_list); 1815 1816 if (_hr_printer.is_active()) { 1817 HeapWord* curr = mr.start(); 1818 while (curr < mr.end()) { 1819 HeapWord* curr_end = curr + HeapRegion::GrainWords; 1820 _hr_printer.commit(curr, curr_end); 1821 curr = curr_end; 1822 } 1823 assert(curr == mr.end(), "post-condition"); 1824 } 1825 g1_policy()->record_new_heap_size(n_regions()); 1826 } else { 1827 ergo_verbose0(ErgoHeapSizing, 1828 "did not expand the heap", 1829 ergo_format_reason("heap expansion operation failed")); 1830 // The expansion of the virtual storage space was unsuccessful. 1831 // Let's see if it was because we ran out of swap. 1832 if (G1ExitOnExpansionFailure && 1833 _g1_storage.uncommitted_size() >= aligned_expand_bytes) { 1834 // We had head room... 1835 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion"); 1836 } 1837 } 1838 return successful; 1839 } 1840 1841 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) { 1842 size_t aligned_shrink_bytes = 1843 ReservedSpace::page_align_size_down(shrink_bytes); 1844 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes, 1845 HeapRegion::GrainBytes); 1846 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes); 1847 1848 uint num_regions_removed = _hrs.shrink_by(num_regions_to_remove); 1849 HeapWord* old_end = (HeapWord*) _g1_storage.high(); 1850 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes; 1851 1852 ergo_verbose3(ErgoHeapSizing, 1853 "shrink the heap", 1854 ergo_format_byte("requested shrinking amount") 1855 ergo_format_byte("aligned shrinking amount") 1856 ergo_format_byte("attempted shrinking amount"), 1857 shrink_bytes, aligned_shrink_bytes, shrunk_bytes); 1858 if (num_regions_removed > 0) { 1859 _g1_storage.shrink_by(shrunk_bytes); 1860 HeapWord* new_end = (HeapWord*) _g1_storage.high(); 1861 1862 if (_hr_printer.is_active()) { 1863 HeapWord* curr = old_end; 1864 while (curr > new_end) { 1865 HeapWord* curr_end = curr; 1866 curr -= HeapRegion::GrainWords; 1867 _hr_printer.uncommit(curr, curr_end); 1868 } 1869 } 1870 1871 _expansion_regions += num_regions_removed; 1872 update_committed_space(old_end, new_end); 1873 HeapRegionRemSet::shrink_heap(n_regions()); 1874 g1_policy()->record_new_heap_size(n_regions()); 1875 } else { 1876 ergo_verbose0(ErgoHeapSizing, 1877 "did not shrink the heap", 1878 ergo_format_reason("heap shrinking operation failed")); 1879 } 1880 } 1881 1882 void G1CollectedHeap::shrink(size_t shrink_bytes) { 1883 verify_region_sets_optional(); 1884 1885 // We should only reach here at the end of a Full GC which means we 1886 // should not not be holding to any GC alloc regions. The method 1887 // below will make sure of that and do any remaining clean up. 1888 abandon_gc_alloc_regions(); 1889 1890 // Instead of tearing down / rebuilding the free lists here, we 1891 // could instead use the remove_all_pending() method on free_list to 1892 // remove only the ones that we need to remove. 1893 tear_down_region_sets(true /* free_list_only */); 1894 shrink_helper(shrink_bytes); 1895 rebuild_region_sets(true /* free_list_only */); 1896 1897 _hrs.verify_optional(); 1898 verify_region_sets_optional(); 1899 } 1900 1901 // Public methods. 1902 1903 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away 1904 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list 1905 #endif // _MSC_VER 1906 1907 1908 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) : 1909 SharedHeap(policy_), 1910 _g1_policy(policy_), 1911 _dirty_card_queue_set(false), 1912 _into_cset_dirty_card_queue_set(false), 1913 _is_alive_closure_cm(this), 1914 _is_alive_closure_stw(this), 1915 _ref_processor_cm(NULL), 1916 _ref_processor_stw(NULL), 1917 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)), 1918 _bot_shared(NULL), 1919 _evac_failure_scan_stack(NULL), 1920 _mark_in_progress(false), 1921 _cg1r(NULL), _summary_bytes_used(0), 1922 _g1mm(NULL), 1923 _refine_cte_cl(NULL), 1924 _full_collection(false), 1925 _free_list("Master Free List", new MasterFreeRegionListMtSafeChecker()), 1926 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()), 1927 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()), 1928 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()), 1929 _free_regions_coming(false), 1930 _young_list(new YoungList(this)), 1931 _gc_time_stamp(0), 1932 _retained_old_gc_alloc_region(NULL), 1933 _survivor_plab_stats(YoungPLABSize, PLABWeight), 1934 _old_plab_stats(OldPLABSize, PLABWeight), 1935 _expand_heap_after_alloc_failure(true), 1936 _surviving_young_words(NULL), 1937 _old_marking_cycles_started(0), 1938 _old_marking_cycles_completed(0), 1939 _concurrent_cycle_started(false), 1940 _in_cset_fast_test(), 1941 _dirty_cards_region_list(NULL), 1942 _worker_cset_start_region(NULL), 1943 _worker_cset_start_region_time_stamp(NULL), 1944 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()), 1945 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()), 1946 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()), 1947 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) { 1948 1949 _g1h = this; 1950 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) { 1951 vm_exit_during_initialization("Failed necessary allocation."); 1952 } 1953 1954 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2; 1955 1956 int n_queues = MAX2((int)ParallelGCThreads, 1); 1957 _task_queues = new RefToScanQueueSet(n_queues); 1958 1959 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets(); 1960 assert(n_rem_sets > 0, "Invariant."); 1961 1962 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC); 1963 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(unsigned int, n_queues, mtGC); 1964 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC); 1965 1966 for (int i = 0; i < n_queues; i++) { 1967 RefToScanQueue* q = new RefToScanQueue(); 1968 q->initialize(); 1969 _task_queues->register_queue(i, q); 1970 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo(); 1971 } 1972 clear_cset_start_regions(); 1973 1974 // Initialize the G1EvacuationFailureALot counters and flags. 1975 NOT_PRODUCT(reset_evacuation_should_fail();) 1976 1977 guarantee(_task_queues != NULL, "task_queues allocation failure."); 1978 } 1979 1980 jint G1CollectedHeap::initialize() { 1981 CollectedHeap::pre_initialize(); 1982 os::enable_vtime(); 1983 1984 G1Log::init(); 1985 1986 // Necessary to satisfy locking discipline assertions. 1987 1988 MutexLocker x(Heap_lock); 1989 1990 // We have to initialize the printer before committing the heap, as 1991 // it will be used then. 1992 _hr_printer.set_active(G1PrintHeapRegions); 1993 1994 // While there are no constraints in the GC code that HeapWordSize 1995 // be any particular value, there are multiple other areas in the 1996 // system which believe this to be true (e.g. oop->object_size in some 1997 // cases incorrectly returns the size in wordSize units rather than 1998 // HeapWordSize). 1999 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 2000 2001 size_t init_byte_size = collector_policy()->initial_heap_byte_size(); 2002 size_t max_byte_size = collector_policy()->max_heap_byte_size(); 2003 size_t heap_alignment = collector_policy()->heap_alignment(); 2004 2005 // Ensure that the sizes are properly aligned. 2006 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap"); 2007 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap"); 2008 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap"); 2009 2010 _refine_cte_cl = new RefineCardTableEntryClosure(); 2011 2012 _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl); 2013 2014 // Reserve the maximum. 2015 2016 // When compressed oops are enabled, the preferred heap base 2017 // is calculated by subtracting the requested size from the 2018 // 32Gb boundary and using the result as the base address for 2019 // heap reservation. If the requested size is not aligned to 2020 // HeapRegion::GrainBytes (i.e. the alignment that is passed 2021 // into the ReservedHeapSpace constructor) then the actual 2022 // base of the reserved heap may end up differing from the 2023 // address that was requested (i.e. the preferred heap base). 2024 // If this happens then we could end up using a non-optimal 2025 // compressed oops mode. 2026 2027 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size, 2028 heap_alignment); 2029 2030 // It is important to do this in a way such that concurrent readers can't 2031 // temporarily think something is in the heap. (I've actually seen this 2032 // happen in asserts: DLD.) 2033 _reserved.set_word_size(0); 2034 _reserved.set_start((HeapWord*)heap_rs.base()); 2035 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size())); 2036 2037 _expansion_regions = (uint) (max_byte_size / HeapRegion::GrainBytes); 2038 2039 // Create the gen rem set (and barrier set) for the entire reserved region. 2040 _rem_set = collector_policy()->create_rem_set(_reserved, 2); 2041 set_barrier_set(rem_set()->bs()); 2042 if (!barrier_set()->is_a(BarrierSet::G1SATBCTLogging)) { 2043 vm_exit_during_initialization("G1 requires a G1SATBLoggingCardTableModRefBS"); 2044 return JNI_ENOMEM; 2045 } 2046 2047 // Also create a G1 rem set. 2048 _g1_rem_set = new G1RemSet(this, g1_barrier_set()); 2049 2050 // Carve out the G1 part of the heap. 2051 2052 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size); 2053 _g1_reserved = MemRegion((HeapWord*)g1_rs.base(), 2054 g1_rs.size()/HeapWordSize); 2055 2056 _g1_storage.initialize(g1_rs, 0); 2057 _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0); 2058 _hrs.initialize((HeapWord*) _g1_reserved.start(), 2059 (HeapWord*) _g1_reserved.end()); 2060 assert(_hrs.max_length() == _expansion_regions, 2061 err_msg("max length: %u expansion regions: %u", 2062 _hrs.max_length(), _expansion_regions)); 2063 2064 // Do later initialization work for concurrent refinement. 2065 _cg1r->init(); 2066 2067 // 6843694 - ensure that the maximum region index can fit 2068 // in the remembered set structures. 2069 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; 2070 guarantee((max_regions() - 1) <= max_region_idx, "too many regions"); 2071 2072 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; 2073 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); 2074 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region, 2075 "too many cards per region"); 2076 2077 FreeRegionList::set_unrealistically_long_length(max_regions() + 1); 2078 2079 _bot_shared = new G1BlockOffsetSharedArray(_reserved, 2080 heap_word_size(init_byte_size)); 2081 2082 _g1h = this; 2083 2084 _in_cset_fast_test.initialize(_g1_reserved.start(), _g1_reserved.end(), HeapRegion::GrainBytes); 2085 2086 // Create the ConcurrentMark data structure and thread. 2087 // (Must do this late, so that "max_regions" is defined.) 2088 _cm = new ConcurrentMark(this, heap_rs); 2089 if (_cm == NULL || !_cm->completed_initialization()) { 2090 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark"); 2091 return JNI_ENOMEM; 2092 } 2093 _cmThread = _cm->cmThread(); 2094 2095 // Initialize the from_card cache structure of HeapRegionRemSet. 2096 HeapRegionRemSet::init_heap(max_regions()); 2097 2098 // Now expand into the initial heap size. 2099 if (!expand(init_byte_size)) { 2100 vm_shutdown_during_initialization("Failed to allocate initial heap."); 2101 return JNI_ENOMEM; 2102 } 2103 2104 // Perform any initialization actions delegated to the policy. 2105 g1_policy()->init(); 2106 2107 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon, 2108 SATB_Q_FL_lock, 2109 G1SATBProcessCompletedThreshold, 2110 Shared_SATB_Q_lock); 2111 2112 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl, 2113 DirtyCardQ_CBL_mon, 2114 DirtyCardQ_FL_lock, 2115 concurrent_g1_refine()->yellow_zone(), 2116 concurrent_g1_refine()->red_zone(), 2117 Shared_DirtyCardQ_lock); 2118 2119 if (G1DeferredRSUpdate) { 2120 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code 2121 DirtyCardQ_CBL_mon, 2122 DirtyCardQ_FL_lock, 2123 -1, // never trigger processing 2124 -1, // no limit on length 2125 Shared_DirtyCardQ_lock, 2126 &JavaThread::dirty_card_queue_set()); 2127 } 2128 2129 // Initialize the card queue set used to hold cards containing 2130 // references into the collection set. 2131 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code 2132 DirtyCardQ_CBL_mon, 2133 DirtyCardQ_FL_lock, 2134 -1, // never trigger processing 2135 -1, // no limit on length 2136 Shared_DirtyCardQ_lock, 2137 &JavaThread::dirty_card_queue_set()); 2138 2139 // In case we're keeping closure specialization stats, initialize those 2140 // counts and that mechanism. 2141 SpecializationStats::clear(); 2142 2143 // Here we allocate the dummy full region that is required by the 2144 // G1AllocRegion class. If we don't pass an address in the reserved 2145 // space here, lots of asserts fire. 2146 2147 HeapRegion* dummy_region = new_heap_region(0 /* index of bottom region */, 2148 _g1_reserved.start()); 2149 // We'll re-use the same region whether the alloc region will 2150 // require BOT updates or not and, if it doesn't, then a non-young 2151 // region will complain that it cannot support allocations without 2152 // BOT updates. So we'll tag the dummy region as young to avoid that. 2153 dummy_region->set_young(); 2154 // Make sure it's full. 2155 dummy_region->set_top(dummy_region->end()); 2156 G1AllocRegion::setup(this, dummy_region); 2157 2158 init_mutator_alloc_region(); 2159 2160 // Do create of the monitoring and management support so that 2161 // values in the heap have been properly initialized. 2162 _g1mm = new G1MonitoringSupport(this); 2163 2164 G1StringDedup::initialize(); 2165 2166 return JNI_OK; 2167 } 2168 2169 void G1CollectedHeap::stop() { 2170 // Stop all concurrent threads. We do this to make sure these threads 2171 // do not continue to execute and access resources (e.g. gclog_or_tty) 2172 // that are destroyed during shutdown. 2173 _cg1r->stop(); 2174 _cmThread->stop(); 2175 if (G1StringDedup::is_enabled()) { 2176 G1StringDedup::stop(); 2177 } 2178 } 2179 2180 size_t G1CollectedHeap::conservative_max_heap_alignment() { 2181 return HeapRegion::max_region_size(); 2182 } 2183 2184 void G1CollectedHeap::ref_processing_init() { 2185 // Reference processing in G1 currently works as follows: 2186 // 2187 // * There are two reference processor instances. One is 2188 // used to record and process discovered references 2189 // during concurrent marking; the other is used to 2190 // record and process references during STW pauses 2191 // (both full and incremental). 2192 // * Both ref processors need to 'span' the entire heap as 2193 // the regions in the collection set may be dotted around. 2194 // 2195 // * For the concurrent marking ref processor: 2196 // * Reference discovery is enabled at initial marking. 2197 // * Reference discovery is disabled and the discovered 2198 // references processed etc during remarking. 2199 // * Reference discovery is MT (see below). 2200 // * Reference discovery requires a barrier (see below). 2201 // * Reference processing may or may not be MT 2202 // (depending on the value of ParallelRefProcEnabled 2203 // and ParallelGCThreads). 2204 // * A full GC disables reference discovery by the CM 2205 // ref processor and abandons any entries on it's 2206 // discovered lists. 2207 // 2208 // * For the STW processor: 2209 // * Non MT discovery is enabled at the start of a full GC. 2210 // * Processing and enqueueing during a full GC is non-MT. 2211 // * During a full GC, references are processed after marking. 2212 // 2213 // * Discovery (may or may not be MT) is enabled at the start 2214 // of an incremental evacuation pause. 2215 // * References are processed near the end of a STW evacuation pause. 2216 // * For both types of GC: 2217 // * Discovery is atomic - i.e. not concurrent. 2218 // * Reference discovery will not need a barrier. 2219 2220 SharedHeap::ref_processing_init(); 2221 MemRegion mr = reserved_region(); 2222 2223 // Concurrent Mark ref processor 2224 _ref_processor_cm = 2225 new ReferenceProcessor(mr, // span 2226 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2227 // mt processing 2228 (int) ParallelGCThreads, 2229 // degree of mt processing 2230 (ParallelGCThreads > 1) || (ConcGCThreads > 1), 2231 // mt discovery 2232 (int) MAX2(ParallelGCThreads, ConcGCThreads), 2233 // degree of mt discovery 2234 false, 2235 // Reference discovery is not atomic 2236 &_is_alive_closure_cm); 2237 // is alive closure 2238 // (for efficiency/performance) 2239 2240 // STW ref processor 2241 _ref_processor_stw = 2242 new ReferenceProcessor(mr, // span 2243 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2244 // mt processing 2245 MAX2((int)ParallelGCThreads, 1), 2246 // degree of mt processing 2247 (ParallelGCThreads > 1), 2248 // mt discovery 2249 MAX2((int)ParallelGCThreads, 1), 2250 // degree of mt discovery 2251 true, 2252 // Reference discovery is atomic 2253 &_is_alive_closure_stw); 2254 // is alive closure 2255 // (for efficiency/performance) 2256 } 2257 2258 size_t G1CollectedHeap::capacity() const { 2259 return _g1_committed.byte_size(); 2260 } 2261 2262 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) { 2263 assert(!hr->continuesHumongous(), "pre-condition"); 2264 hr->reset_gc_time_stamp(); 2265 if (hr->startsHumongous()) { 2266 uint first_index = hr->hrs_index() + 1; 2267 uint last_index = hr->last_hc_index(); 2268 for (uint i = first_index; i < last_index; i += 1) { 2269 HeapRegion* chr = region_at(i); 2270 assert(chr->continuesHumongous(), "sanity"); 2271 chr->reset_gc_time_stamp(); 2272 } 2273 } 2274 } 2275 2276 #ifndef PRODUCT 2277 class CheckGCTimeStampsHRClosure : public HeapRegionClosure { 2278 private: 2279 unsigned _gc_time_stamp; 2280 bool _failures; 2281 2282 public: 2283 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) : 2284 _gc_time_stamp(gc_time_stamp), _failures(false) { } 2285 2286 virtual bool doHeapRegion(HeapRegion* hr) { 2287 unsigned region_gc_time_stamp = hr->get_gc_time_stamp(); 2288 if (_gc_time_stamp != region_gc_time_stamp) { 2289 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, " 2290 "expected %d", HR_FORMAT_PARAMS(hr), 2291 region_gc_time_stamp, _gc_time_stamp); 2292 _failures = true; 2293 } 2294 return false; 2295 } 2296 2297 bool failures() { return _failures; } 2298 }; 2299 2300 void G1CollectedHeap::check_gc_time_stamps() { 2301 CheckGCTimeStampsHRClosure cl(_gc_time_stamp); 2302 heap_region_iterate(&cl); 2303 guarantee(!cl.failures(), "all GC time stamps should have been reset"); 2304 } 2305 #endif // PRODUCT 2306 2307 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, 2308 DirtyCardQueue* into_cset_dcq, 2309 bool concurrent, 2310 uint worker_i) { 2311 // Clean cards in the hot card cache 2312 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 2313 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq); 2314 2315 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 2316 int n_completed_buffers = 0; 2317 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) { 2318 n_completed_buffers++; 2319 } 2320 g1_policy()->phase_times()->record_update_rs_processed_buffers(worker_i, n_completed_buffers); 2321 dcqs.clear_n_completed_buffers(); 2322 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!"); 2323 } 2324 2325 2326 // Computes the sum of the storage used by the various regions. 2327 2328 size_t G1CollectedHeap::used() const { 2329 assert(Heap_lock->owner() != NULL, 2330 "Should be owned on this thread's behalf."); 2331 size_t result = _summary_bytes_used; 2332 // Read only once in case it is set to NULL concurrently 2333 HeapRegion* hr = _mutator_alloc_region.get(); 2334 if (hr != NULL) 2335 result += hr->used(); 2336 return result; 2337 } 2338 2339 size_t G1CollectedHeap::used_unlocked() const { 2340 size_t result = _summary_bytes_used; 2341 return result; 2342 } 2343 2344 class SumUsedClosure: public HeapRegionClosure { 2345 size_t _used; 2346 public: 2347 SumUsedClosure() : _used(0) {} 2348 bool doHeapRegion(HeapRegion* r) { 2349 if (!r->continuesHumongous()) { 2350 _used += r->used(); 2351 } 2352 return false; 2353 } 2354 size_t result() { return _used; } 2355 }; 2356 2357 size_t G1CollectedHeap::recalculate_used() const { 2358 double recalculate_used_start = os::elapsedTime(); 2359 2360 SumUsedClosure blk; 2361 heap_region_iterate(&blk); 2362 2363 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0); 2364 return blk.result(); 2365 } 2366 2367 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 2368 switch (cause) { 2369 case GCCause::_gc_locker: return GCLockerInvokesConcurrent; 2370 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent; 2371 case GCCause::_g1_humongous_allocation: return true; 2372 default: return false; 2373 } 2374 } 2375 2376 #ifndef PRODUCT 2377 void G1CollectedHeap::allocate_dummy_regions() { 2378 // Let's fill up most of the region 2379 size_t word_size = HeapRegion::GrainWords - 1024; 2380 // And as a result the region we'll allocate will be humongous. 2381 guarantee(isHumongous(word_size), "sanity"); 2382 2383 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) { 2384 // Let's use the existing mechanism for the allocation 2385 HeapWord* dummy_obj = humongous_obj_allocate(word_size); 2386 if (dummy_obj != NULL) { 2387 MemRegion mr(dummy_obj, word_size); 2388 CollectedHeap::fill_with_object(mr); 2389 } else { 2390 // If we can't allocate once, we probably cannot allocate 2391 // again. Let's get out of the loop. 2392 break; 2393 } 2394 } 2395 } 2396 #endif // !PRODUCT 2397 2398 void G1CollectedHeap::increment_old_marking_cycles_started() { 2399 assert(_old_marking_cycles_started == _old_marking_cycles_completed || 2400 _old_marking_cycles_started == _old_marking_cycles_completed + 1, 2401 err_msg("Wrong marking cycle count (started: %d, completed: %d)", 2402 _old_marking_cycles_started, _old_marking_cycles_completed)); 2403 2404 _old_marking_cycles_started++; 2405 } 2406 2407 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) { 2408 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 2409 2410 // We assume that if concurrent == true, then the caller is a 2411 // concurrent thread that was joined the Suspendible Thread 2412 // Set. If there's ever a cheap way to check this, we should add an 2413 // assert here. 2414 2415 // Given that this method is called at the end of a Full GC or of a 2416 // concurrent cycle, and those can be nested (i.e., a Full GC can 2417 // interrupt a concurrent cycle), the number of full collections 2418 // completed should be either one (in the case where there was no 2419 // nesting) or two (when a Full GC interrupted a concurrent cycle) 2420 // behind the number of full collections started. 2421 2422 // This is the case for the inner caller, i.e. a Full GC. 2423 assert(concurrent || 2424 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || 2425 (_old_marking_cycles_started == _old_marking_cycles_completed + 2), 2426 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u " 2427 "is inconsistent with _old_marking_cycles_completed = %u", 2428 _old_marking_cycles_started, _old_marking_cycles_completed)); 2429 2430 // This is the case for the outer caller, i.e. the concurrent cycle. 2431 assert(!concurrent || 2432 (_old_marking_cycles_started == _old_marking_cycles_completed + 1), 2433 err_msg("for outer caller (concurrent cycle): " 2434 "_old_marking_cycles_started = %u " 2435 "is inconsistent with _old_marking_cycles_completed = %u", 2436 _old_marking_cycles_started, _old_marking_cycles_completed)); 2437 2438 _old_marking_cycles_completed += 1; 2439 2440 // We need to clear the "in_progress" flag in the CM thread before 2441 // we wake up any waiters (especially when ExplicitInvokesConcurrent 2442 // is set) so that if a waiter requests another System.gc() it doesn't 2443 // incorrectly see that a marking cycle is still in progress. 2444 if (concurrent) { 2445 _cmThread->clear_in_progress(); 2446 } 2447 2448 // This notify_all() will ensure that a thread that called 2449 // System.gc() with (with ExplicitGCInvokesConcurrent set or not) 2450 // and it's waiting for a full GC to finish will be woken up. It is 2451 // waiting in VM_G1IncCollectionPause::doit_epilogue(). 2452 FullGCCount_lock->notify_all(); 2453 } 2454 2455 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) { 2456 _concurrent_cycle_started = true; 2457 _gc_timer_cm->register_gc_start(start_time); 2458 2459 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start()); 2460 trace_heap_before_gc(_gc_tracer_cm); 2461 } 2462 2463 void G1CollectedHeap::register_concurrent_cycle_end() { 2464 if (_concurrent_cycle_started) { 2465 if (_cm->has_aborted()) { 2466 _gc_tracer_cm->report_concurrent_mode_failure(); 2467 } 2468 2469 _gc_timer_cm->register_gc_end(); 2470 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions()); 2471 2472 _concurrent_cycle_started = false; 2473 } 2474 } 2475 2476 void G1CollectedHeap::trace_heap_after_concurrent_cycle() { 2477 if (_concurrent_cycle_started) { 2478 trace_heap_after_gc(_gc_tracer_cm); 2479 } 2480 } 2481 2482 G1YCType G1CollectedHeap::yc_type() { 2483 bool is_young = g1_policy()->gcs_are_young(); 2484 bool is_initial_mark = g1_policy()->during_initial_mark_pause(); 2485 bool is_during_mark = mark_in_progress(); 2486 2487 if (is_initial_mark) { 2488 return InitialMark; 2489 } else if (is_during_mark) { 2490 return DuringMark; 2491 } else if (is_young) { 2492 return Normal; 2493 } else { 2494 return Mixed; 2495 } 2496 } 2497 2498 void G1CollectedHeap::collect(GCCause::Cause cause) { 2499 assert_heap_not_locked(); 2500 2501 unsigned int gc_count_before; 2502 unsigned int old_marking_count_before; 2503 bool retry_gc; 2504 2505 do { 2506 retry_gc = false; 2507 2508 { 2509 MutexLocker ml(Heap_lock); 2510 2511 // Read the GC count while holding the Heap_lock 2512 gc_count_before = total_collections(); 2513 old_marking_count_before = _old_marking_cycles_started; 2514 } 2515 2516 if (should_do_concurrent_full_gc(cause)) { 2517 // Schedule an initial-mark evacuation pause that will start a 2518 // concurrent cycle. We're setting word_size to 0 which means that 2519 // we are not requesting a post-GC allocation. 2520 VM_G1IncCollectionPause op(gc_count_before, 2521 0, /* word_size */ 2522 true, /* should_initiate_conc_mark */ 2523 g1_policy()->max_pause_time_ms(), 2524 cause); 2525 2526 VMThread::execute(&op); 2527 if (!op.pause_succeeded()) { 2528 if (old_marking_count_before == _old_marking_cycles_started) { 2529 retry_gc = op.should_retry_gc(); 2530 } else { 2531 // A Full GC happened while we were trying to schedule the 2532 // initial-mark GC. No point in starting a new cycle given 2533 // that the whole heap was collected anyway. 2534 } 2535 2536 if (retry_gc) { 2537 if (GC_locker::is_active_and_needs_gc()) { 2538 GC_locker::stall_until_clear(); 2539 } 2540 } 2541 } 2542 } else { 2543 if (cause == GCCause::_gc_locker 2544 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { 2545 2546 // Schedule a standard evacuation pause. We're setting word_size 2547 // to 0 which means that we are not requesting a post-GC allocation. 2548 VM_G1IncCollectionPause op(gc_count_before, 2549 0, /* word_size */ 2550 false, /* should_initiate_conc_mark */ 2551 g1_policy()->max_pause_time_ms(), 2552 cause); 2553 VMThread::execute(&op); 2554 } else { 2555 // Schedule a Full GC. 2556 VM_G1CollectFull op(gc_count_before, old_marking_count_before, cause); 2557 VMThread::execute(&op); 2558 } 2559 } 2560 } while (retry_gc); 2561 } 2562 2563 bool G1CollectedHeap::is_in(const void* p) const { 2564 if (_g1_committed.contains(p)) { 2565 // Given that we know that p is in the committed space, 2566 // heap_region_containing_raw() should successfully 2567 // return the containing region. 2568 HeapRegion* hr = heap_region_containing_raw(p); 2569 return hr->is_in(p); 2570 } else { 2571 return false; 2572 } 2573 } 2574 2575 // Iteration functions. 2576 2577 // Iterates an OopClosure over all ref-containing fields of objects 2578 // within a HeapRegion. 2579 2580 class IterateOopClosureRegionClosure: public HeapRegionClosure { 2581 MemRegion _mr; 2582 ExtendedOopClosure* _cl; 2583 public: 2584 IterateOopClosureRegionClosure(MemRegion mr, ExtendedOopClosure* cl) 2585 : _mr(mr), _cl(cl) {} 2586 bool doHeapRegion(HeapRegion* r) { 2587 if (!r->continuesHumongous()) { 2588 r->oop_iterate(_cl); 2589 } 2590 return false; 2591 } 2592 }; 2593 2594 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) { 2595 IterateOopClosureRegionClosure blk(_g1_committed, cl); 2596 heap_region_iterate(&blk); 2597 } 2598 2599 void G1CollectedHeap::oop_iterate(MemRegion mr, ExtendedOopClosure* cl) { 2600 IterateOopClosureRegionClosure blk(mr, cl); 2601 heap_region_iterate(&blk); 2602 } 2603 2604 // Iterates an ObjectClosure over all objects within a HeapRegion. 2605 2606 class IterateObjectClosureRegionClosure: public HeapRegionClosure { 2607 ObjectClosure* _cl; 2608 public: 2609 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} 2610 bool doHeapRegion(HeapRegion* r) { 2611 if (! r->continuesHumongous()) { 2612 r->object_iterate(_cl); 2613 } 2614 return false; 2615 } 2616 }; 2617 2618 void G1CollectedHeap::object_iterate(ObjectClosure* cl) { 2619 IterateObjectClosureRegionClosure blk(cl); 2620 heap_region_iterate(&blk); 2621 } 2622 2623 // Calls a SpaceClosure on a HeapRegion. 2624 2625 class SpaceClosureRegionClosure: public HeapRegionClosure { 2626 SpaceClosure* _cl; 2627 public: 2628 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {} 2629 bool doHeapRegion(HeapRegion* r) { 2630 _cl->do_space(r); 2631 return false; 2632 } 2633 }; 2634 2635 void G1CollectedHeap::space_iterate(SpaceClosure* cl) { 2636 SpaceClosureRegionClosure blk(cl); 2637 heap_region_iterate(&blk); 2638 } 2639 2640 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { 2641 _hrs.iterate(cl); 2642 } 2643 2644 void 2645 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl, 2646 uint worker_id, 2647 uint no_of_par_workers, 2648 jint claim_value) { 2649 const uint regions = n_regions(); 2650 const uint max_workers = (G1CollectedHeap::use_parallel_gc_threads() ? 2651 no_of_par_workers : 2652 1); 2653 assert(UseDynamicNumberOfGCThreads || 2654 no_of_par_workers == workers()->total_workers(), 2655 "Non dynamic should use fixed number of workers"); 2656 // try to spread out the starting points of the workers 2657 const HeapRegion* start_hr = 2658 start_region_for_worker(worker_id, no_of_par_workers); 2659 const uint start_index = start_hr->hrs_index(); 2660 2661 // each worker will actually look at all regions 2662 for (uint count = 0; count < regions; ++count) { 2663 const uint index = (start_index + count) % regions; 2664 assert(0 <= index && index < regions, "sanity"); 2665 HeapRegion* r = region_at(index); 2666 // we'll ignore "continues humongous" regions (we'll process them 2667 // when we come across their corresponding "start humongous" 2668 // region) and regions already claimed 2669 if (r->claim_value() == claim_value || r->continuesHumongous()) { 2670 continue; 2671 } 2672 // OK, try to claim it 2673 if (r->claimHeapRegion(claim_value)) { 2674 // success! 2675 assert(!r->continuesHumongous(), "sanity"); 2676 if (r->startsHumongous()) { 2677 // If the region is "starts humongous" we'll iterate over its 2678 // "continues humongous" first; in fact we'll do them 2679 // first. The order is important. In on case, calling the 2680 // closure on the "starts humongous" region might de-allocate 2681 // and clear all its "continues humongous" regions and, as a 2682 // result, we might end up processing them twice. So, we'll do 2683 // them first (notice: most closures will ignore them anyway) and 2684 // then we'll do the "starts humongous" region. 2685 for (uint ch_index = index + 1; ch_index < regions; ++ch_index) { 2686 HeapRegion* chr = region_at(ch_index); 2687 2688 // if the region has already been claimed or it's not 2689 // "continues humongous" we're done 2690 if (chr->claim_value() == claim_value || 2691 !chr->continuesHumongous()) { 2692 break; 2693 } 2694 2695 // No one should have claimed it directly. We can given 2696 // that we claimed its "starts humongous" region. 2697 assert(chr->claim_value() != claim_value, "sanity"); 2698 assert(chr->humongous_start_region() == r, "sanity"); 2699 2700 if (chr->claimHeapRegion(claim_value)) { 2701 // we should always be able to claim it; no one else should 2702 // be trying to claim this region 2703 2704 bool res2 = cl->doHeapRegion(chr); 2705 assert(!res2, "Should not abort"); 2706 2707 // Right now, this holds (i.e., no closure that actually 2708 // does something with "continues humongous" regions 2709 // clears them). We might have to weaken it in the future, 2710 // but let's leave these two asserts here for extra safety. 2711 assert(chr->continuesHumongous(), "should still be the case"); 2712 assert(chr->humongous_start_region() == r, "sanity"); 2713 } else { 2714 guarantee(false, "we should not reach here"); 2715 } 2716 } 2717 } 2718 2719 assert(!r->continuesHumongous(), "sanity"); 2720 bool res = cl->doHeapRegion(r); 2721 assert(!res, "Should not abort"); 2722 } 2723 } 2724 } 2725 2726 class ResetClaimValuesClosure: public HeapRegionClosure { 2727 public: 2728 bool doHeapRegion(HeapRegion* r) { 2729 r->set_claim_value(HeapRegion::InitialClaimValue); 2730 return false; 2731 } 2732 }; 2733 2734 void G1CollectedHeap::reset_heap_region_claim_values() { 2735 ResetClaimValuesClosure blk; 2736 heap_region_iterate(&blk); 2737 } 2738 2739 void G1CollectedHeap::reset_cset_heap_region_claim_values() { 2740 ResetClaimValuesClosure blk; 2741 collection_set_iterate(&blk); 2742 } 2743 2744 #ifdef ASSERT 2745 // This checks whether all regions in the heap have the correct claim 2746 // value. I also piggy-backed on this a check to ensure that the 2747 // humongous_start_region() information on "continues humongous" 2748 // regions is correct. 2749 2750 class CheckClaimValuesClosure : public HeapRegionClosure { 2751 private: 2752 jint _claim_value; 2753 uint _failures; 2754 HeapRegion* _sh_region; 2755 2756 public: 2757 CheckClaimValuesClosure(jint claim_value) : 2758 _claim_value(claim_value), _failures(0), _sh_region(NULL) { } 2759 bool doHeapRegion(HeapRegion* r) { 2760 if (r->claim_value() != _claim_value) { 2761 gclog_or_tty->print_cr("Region " HR_FORMAT ", " 2762 "claim value = %d, should be %d", 2763 HR_FORMAT_PARAMS(r), 2764 r->claim_value(), _claim_value); 2765 ++_failures; 2766 } 2767 if (!r->isHumongous()) { 2768 _sh_region = NULL; 2769 } else if (r->startsHumongous()) { 2770 _sh_region = r; 2771 } else if (r->continuesHumongous()) { 2772 if (r->humongous_start_region() != _sh_region) { 2773 gclog_or_tty->print_cr("Region " HR_FORMAT ", " 2774 "HS = "PTR_FORMAT", should be "PTR_FORMAT, 2775 HR_FORMAT_PARAMS(r), 2776 r->humongous_start_region(), 2777 _sh_region); 2778 ++_failures; 2779 } 2780 } 2781 return false; 2782 } 2783 uint failures() { return _failures; } 2784 }; 2785 2786 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) { 2787 CheckClaimValuesClosure cl(claim_value); 2788 heap_region_iterate(&cl); 2789 return cl.failures() == 0; 2790 } 2791 2792 class CheckClaimValuesInCSetHRClosure: public HeapRegionClosure { 2793 private: 2794 jint _claim_value; 2795 uint _failures; 2796 2797 public: 2798 CheckClaimValuesInCSetHRClosure(jint claim_value) : 2799 _claim_value(claim_value), _failures(0) { } 2800 2801 uint failures() { return _failures; } 2802 2803 bool doHeapRegion(HeapRegion* hr) { 2804 assert(hr->in_collection_set(), "how?"); 2805 assert(!hr->isHumongous(), "H-region in CSet"); 2806 if (hr->claim_value() != _claim_value) { 2807 gclog_or_tty->print_cr("CSet Region " HR_FORMAT ", " 2808 "claim value = %d, should be %d", 2809 HR_FORMAT_PARAMS(hr), 2810 hr->claim_value(), _claim_value); 2811 _failures += 1; 2812 } 2813 return false; 2814 } 2815 }; 2816 2817 bool G1CollectedHeap::check_cset_heap_region_claim_values(jint claim_value) { 2818 CheckClaimValuesInCSetHRClosure cl(claim_value); 2819 collection_set_iterate(&cl); 2820 return cl.failures() == 0; 2821 } 2822 #endif // ASSERT 2823 2824 // Clear the cached CSet starting regions and (more importantly) 2825 // the time stamps. Called when we reset the GC time stamp. 2826 void G1CollectedHeap::clear_cset_start_regions() { 2827 assert(_worker_cset_start_region != NULL, "sanity"); 2828 assert(_worker_cset_start_region_time_stamp != NULL, "sanity"); 2829 2830 int n_queues = MAX2((int)ParallelGCThreads, 1); 2831 for (int i = 0; i < n_queues; i++) { 2832 _worker_cset_start_region[i] = NULL; 2833 _worker_cset_start_region_time_stamp[i] = 0; 2834 } 2835 } 2836 2837 // Given the id of a worker, obtain or calculate a suitable 2838 // starting region for iterating over the current collection set. 2839 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) { 2840 assert(get_gc_time_stamp() > 0, "should have been updated by now"); 2841 2842 HeapRegion* result = NULL; 2843 unsigned gc_time_stamp = get_gc_time_stamp(); 2844 2845 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) { 2846 // Cached starting region for current worker was set 2847 // during the current pause - so it's valid. 2848 // Note: the cached starting heap region may be NULL 2849 // (when the collection set is empty). 2850 result = _worker_cset_start_region[worker_i]; 2851 assert(result == NULL || result->in_collection_set(), "sanity"); 2852 return result; 2853 } 2854 2855 // The cached entry was not valid so let's calculate 2856 // a suitable starting heap region for this worker. 2857 2858 // We want the parallel threads to start their collection 2859 // set iteration at different collection set regions to 2860 // avoid contention. 2861 // If we have: 2862 // n collection set regions 2863 // p threads 2864 // Then thread t will start at region floor ((t * n) / p) 2865 2866 result = g1_policy()->collection_set(); 2867 if (G1CollectedHeap::use_parallel_gc_threads()) { 2868 uint cs_size = g1_policy()->cset_region_length(); 2869 uint active_workers = workers()->active_workers(); 2870 assert(UseDynamicNumberOfGCThreads || 2871 active_workers == workers()->total_workers(), 2872 "Unless dynamic should use total workers"); 2873 2874 uint end_ind = (cs_size * worker_i) / active_workers; 2875 uint start_ind = 0; 2876 2877 if (worker_i > 0 && 2878 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) { 2879 // Previous workers starting region is valid 2880 // so let's iterate from there 2881 start_ind = (cs_size * (worker_i - 1)) / active_workers; 2882 result = _worker_cset_start_region[worker_i - 1]; 2883 } 2884 2885 for (uint i = start_ind; i < end_ind; i++) { 2886 result = result->next_in_collection_set(); 2887 } 2888 } 2889 2890 // Note: the calculated starting heap region may be NULL 2891 // (when the collection set is empty). 2892 assert(result == NULL || result->in_collection_set(), "sanity"); 2893 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp, 2894 "should be updated only once per pause"); 2895 _worker_cset_start_region[worker_i] = result; 2896 OrderAccess::storestore(); 2897 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp; 2898 return result; 2899 } 2900 2901 HeapRegion* G1CollectedHeap::start_region_for_worker(uint worker_i, 2902 uint no_of_par_workers) { 2903 uint worker_num = 2904 G1CollectedHeap::use_parallel_gc_threads() ? no_of_par_workers : 1U; 2905 assert(UseDynamicNumberOfGCThreads || 2906 no_of_par_workers == workers()->total_workers(), 2907 "Non dynamic should use fixed number of workers"); 2908 const uint start_index = n_regions() * worker_i / worker_num; 2909 return region_at(start_index); 2910 } 2911 2912 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) { 2913 HeapRegion* r = g1_policy()->collection_set(); 2914 while (r != NULL) { 2915 HeapRegion* next = r->next_in_collection_set(); 2916 if (cl->doHeapRegion(r)) { 2917 cl->incomplete(); 2918 return; 2919 } 2920 r = next; 2921 } 2922 } 2923 2924 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r, 2925 HeapRegionClosure *cl) { 2926 if (r == NULL) { 2927 // The CSet is empty so there's nothing to do. 2928 return; 2929 } 2930 2931 assert(r->in_collection_set(), 2932 "Start region must be a member of the collection set."); 2933 HeapRegion* cur = r; 2934 while (cur != NULL) { 2935 HeapRegion* next = cur->next_in_collection_set(); 2936 if (cl->doHeapRegion(cur) && false) { 2937 cl->incomplete(); 2938 return; 2939 } 2940 cur = next; 2941 } 2942 cur = g1_policy()->collection_set(); 2943 while (cur != r) { 2944 HeapRegion* next = cur->next_in_collection_set(); 2945 if (cl->doHeapRegion(cur) && false) { 2946 cl->incomplete(); 2947 return; 2948 } 2949 cur = next; 2950 } 2951 } 2952 2953 CompactibleSpace* G1CollectedHeap::first_compactible_space() { 2954 return n_regions() > 0 ? region_at(0) : NULL; 2955 } 2956 2957 2958 Space* G1CollectedHeap::space_containing(const void* addr) const { 2959 return heap_region_containing(addr); 2960 } 2961 2962 HeapWord* G1CollectedHeap::block_start(const void* addr) const { 2963 Space* sp = space_containing(addr); 2964 return sp->block_start(addr); 2965 } 2966 2967 size_t G1CollectedHeap::block_size(const HeapWord* addr) const { 2968 Space* sp = space_containing(addr); 2969 return sp->block_size(addr); 2970 } 2971 2972 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { 2973 Space* sp = space_containing(addr); 2974 return sp->block_is_obj(addr); 2975 } 2976 2977 bool G1CollectedHeap::supports_tlab_allocation() const { 2978 return true; 2979 } 2980 2981 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { 2982 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes; 2983 } 2984 2985 size_t G1CollectedHeap::tlab_used(Thread* ignored) const { 2986 return young_list()->eden_used_bytes(); 2987 } 2988 2989 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size 2990 // must be smaller than the humongous object limit. 2991 size_t G1CollectedHeap::max_tlab_size() const { 2992 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment); 2993 } 2994 2995 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { 2996 // Return the remaining space in the cur alloc region, but not less than 2997 // the min TLAB size. 2998 2999 // Also, this value can be at most the humongous object threshold, 3000 // since we can't allow tlabs to grow big enough to accommodate 3001 // humongous objects. 3002 3003 HeapRegion* hr = _mutator_alloc_region.get(); 3004 size_t max_tlab = max_tlab_size() * wordSize; 3005 if (hr == NULL) { 3006 return max_tlab; 3007 } else { 3008 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab); 3009 } 3010 } 3011 3012 size_t G1CollectedHeap::max_capacity() const { 3013 return _g1_reserved.byte_size(); 3014 } 3015 3016 jlong G1CollectedHeap::millis_since_last_gc() { 3017 // assert(false, "NYI"); 3018 return 0; 3019 } 3020 3021 void G1CollectedHeap::prepare_for_verify() { 3022 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) { 3023 ensure_parsability(false); 3024 } 3025 g1_rem_set()->prepare_for_verify(); 3026 } 3027 3028 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr, 3029 VerifyOption vo) { 3030 switch (vo) { 3031 case VerifyOption_G1UsePrevMarking: 3032 return hr->obj_allocated_since_prev_marking(obj); 3033 case VerifyOption_G1UseNextMarking: 3034 return hr->obj_allocated_since_next_marking(obj); 3035 case VerifyOption_G1UseMarkWord: 3036 return false; 3037 default: 3038 ShouldNotReachHere(); 3039 } 3040 return false; // keep some compilers happy 3041 } 3042 3043 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) { 3044 switch (vo) { 3045 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start(); 3046 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start(); 3047 case VerifyOption_G1UseMarkWord: return NULL; 3048 default: ShouldNotReachHere(); 3049 } 3050 return NULL; // keep some compilers happy 3051 } 3052 3053 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) { 3054 switch (vo) { 3055 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj); 3056 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj); 3057 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked(); 3058 default: ShouldNotReachHere(); 3059 } 3060 return false; // keep some compilers happy 3061 } 3062 3063 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) { 3064 switch (vo) { 3065 case VerifyOption_G1UsePrevMarking: return "PTAMS"; 3066 case VerifyOption_G1UseNextMarking: return "NTAMS"; 3067 case VerifyOption_G1UseMarkWord: return "NONE"; 3068 default: ShouldNotReachHere(); 3069 } 3070 return NULL; // keep some compilers happy 3071 } 3072 3073 class VerifyRootsClosure: public OopClosure { 3074 private: 3075 G1CollectedHeap* _g1h; 3076 VerifyOption _vo; 3077 bool _failures; 3078 public: 3079 // _vo == UsePrevMarking -> use "prev" marking information, 3080 // _vo == UseNextMarking -> use "next" marking information, 3081 // _vo == UseMarkWord -> use mark word from object header. 3082 VerifyRootsClosure(VerifyOption vo) : 3083 _g1h(G1CollectedHeap::heap()), 3084 _vo(vo), 3085 _failures(false) { } 3086 3087 bool failures() { return _failures; } 3088 3089 template <class T> void do_oop_nv(T* p) { 3090 T heap_oop = oopDesc::load_heap_oop(p); 3091 if (!oopDesc::is_null(heap_oop)) { 3092 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 3093 if (_g1h->is_obj_dead_cond(obj, _vo)) { 3094 gclog_or_tty->print_cr("Root location "PTR_FORMAT" " 3095 "points to dead obj "PTR_FORMAT, p, (void*) obj); 3096 if (_vo == VerifyOption_G1UseMarkWord) { 3097 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark())); 3098 } 3099 obj->print_on(gclog_or_tty); 3100 _failures = true; 3101 } 3102 } 3103 } 3104 3105 void do_oop(oop* p) { do_oop_nv(p); } 3106 void do_oop(narrowOop* p) { do_oop_nv(p); } 3107 }; 3108 3109 class G1VerifyCodeRootOopClosure: public OopClosure { 3110 G1CollectedHeap* _g1h; 3111 OopClosure* _root_cl; 3112 nmethod* _nm; 3113 VerifyOption _vo; 3114 bool _failures; 3115 3116 template <class T> void do_oop_work(T* p) { 3117 // First verify that this root is live 3118 _root_cl->do_oop(p); 3119 3120 if (!G1VerifyHeapRegionCodeRoots) { 3121 // We're not verifying the code roots attached to heap region. 3122 return; 3123 } 3124 3125 // Don't check the code roots during marking verification in a full GC 3126 if (_vo == VerifyOption_G1UseMarkWord) { 3127 return; 3128 } 3129 3130 // Now verify that the current nmethod (which contains p) is 3131 // in the code root list of the heap region containing the 3132 // object referenced by p. 3133 3134 T heap_oop = oopDesc::load_heap_oop(p); 3135 if (!oopDesc::is_null(heap_oop)) { 3136 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 3137 3138 // Now fetch the region containing the object 3139 HeapRegion* hr = _g1h->heap_region_containing(obj); 3140 HeapRegionRemSet* hrrs = hr->rem_set(); 3141 // Verify that the strong code root list for this region 3142 // contains the nmethod 3143 if (!hrrs->strong_code_roots_list_contains(_nm)) { 3144 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" " 3145 "from nmethod "PTR_FORMAT" not in strong " 3146 "code roots for region ["PTR_FORMAT","PTR_FORMAT")", 3147 p, _nm, hr->bottom(), hr->end()); 3148 _failures = true; 3149 } 3150 } 3151 } 3152 3153 public: 3154 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo): 3155 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {} 3156 3157 void do_oop(oop* p) { do_oop_work(p); } 3158 void do_oop(narrowOop* p) { do_oop_work(p); } 3159 3160 void set_nmethod(nmethod* nm) { _nm = nm; } 3161 bool failures() { return _failures; } 3162 }; 3163 3164 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure { 3165 G1VerifyCodeRootOopClosure* _oop_cl; 3166 3167 public: 3168 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl): 3169 _oop_cl(oop_cl) {} 3170 3171 void do_code_blob(CodeBlob* cb) { 3172 nmethod* nm = cb->as_nmethod_or_null(); 3173 if (nm != NULL) { 3174 _oop_cl->set_nmethod(nm); 3175 nm->oops_do(_oop_cl); 3176 } 3177 } 3178 }; 3179 3180 class YoungRefCounterClosure : public OopClosure { 3181 G1CollectedHeap* _g1h; 3182 int _count; 3183 public: 3184 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {} 3185 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } } 3186 void do_oop(narrowOop* p) { ShouldNotReachHere(); } 3187 3188 int count() { return _count; } 3189 void reset_count() { _count = 0; }; 3190 }; 3191 3192 class VerifyKlassClosure: public KlassClosure { 3193 YoungRefCounterClosure _young_ref_counter_closure; 3194 OopClosure *_oop_closure; 3195 public: 3196 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {} 3197 void do_klass(Klass* k) { 3198 k->oops_do(_oop_closure); 3199 3200 _young_ref_counter_closure.reset_count(); 3201 k->oops_do(&_young_ref_counter_closure); 3202 if (_young_ref_counter_closure.count() > 0) { 3203 guarantee(k->has_modified_oops(), err_msg("Klass " PTR_FORMAT ", has young refs but is not dirty.", k)); 3204 } 3205 } 3206 }; 3207 3208 class VerifyLivenessOopClosure: public OopClosure { 3209 G1CollectedHeap* _g1h; 3210 VerifyOption _vo; 3211 public: 3212 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo): 3213 _g1h(g1h), _vo(vo) 3214 { } 3215 void do_oop(narrowOop *p) { do_oop_work(p); } 3216 void do_oop( oop *p) { do_oop_work(p); } 3217 3218 template <class T> void do_oop_work(T *p) { 3219 oop obj = oopDesc::load_decode_heap_oop(p); 3220 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo), 3221 "Dead object referenced by a not dead object"); 3222 } 3223 }; 3224 3225 class VerifyObjsInRegionClosure: public ObjectClosure { 3226 private: 3227 G1CollectedHeap* _g1h; 3228 size_t _live_bytes; 3229 HeapRegion *_hr; 3230 VerifyOption _vo; 3231 public: 3232 // _vo == UsePrevMarking -> use "prev" marking information, 3233 // _vo == UseNextMarking -> use "next" marking information, 3234 // _vo == UseMarkWord -> use mark word from object header. 3235 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo) 3236 : _live_bytes(0), _hr(hr), _vo(vo) { 3237 _g1h = G1CollectedHeap::heap(); 3238 } 3239 void do_object(oop o) { 3240 VerifyLivenessOopClosure isLive(_g1h, _vo); 3241 assert(o != NULL, "Huh?"); 3242 if (!_g1h->is_obj_dead_cond(o, _vo)) { 3243 // If the object is alive according to the mark word, 3244 // then verify that the marking information agrees. 3245 // Note we can't verify the contra-positive of the 3246 // above: if the object is dead (according to the mark 3247 // word), it may not be marked, or may have been marked 3248 // but has since became dead, or may have been allocated 3249 // since the last marking. 3250 if (_vo == VerifyOption_G1UseMarkWord) { 3251 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch"); 3252 } 3253 3254 o->oop_iterate_no_header(&isLive); 3255 if (!_hr->obj_allocated_since_prev_marking(o)) { 3256 size_t obj_size = o->size(); // Make sure we don't overflow 3257 _live_bytes += (obj_size * HeapWordSize); 3258 } 3259 } 3260 } 3261 size_t live_bytes() { return _live_bytes; } 3262 }; 3263 3264 class PrintObjsInRegionClosure : public ObjectClosure { 3265 HeapRegion *_hr; 3266 G1CollectedHeap *_g1; 3267 public: 3268 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) { 3269 _g1 = G1CollectedHeap::heap(); 3270 }; 3271 3272 void do_object(oop o) { 3273 if (o != NULL) { 3274 HeapWord *start = (HeapWord *) o; 3275 size_t word_sz = o->size(); 3276 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT 3277 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n", 3278 (void*) o, word_sz, 3279 _g1->isMarkedPrev(o), 3280 _g1->isMarkedNext(o), 3281 _hr->obj_allocated_since_prev_marking(o)); 3282 HeapWord *end = start + word_sz; 3283 HeapWord *cur; 3284 int *val; 3285 for (cur = start; cur < end; cur++) { 3286 val = (int *) cur; 3287 gclog_or_tty->print("\t "PTR_FORMAT":%d\n", val, *val); 3288 } 3289 } 3290 } 3291 }; 3292 3293 class VerifyRegionClosure: public HeapRegionClosure { 3294 private: 3295 bool _par; 3296 VerifyOption _vo; 3297 bool _failures; 3298 public: 3299 // _vo == UsePrevMarking -> use "prev" marking information, 3300 // _vo == UseNextMarking -> use "next" marking information, 3301 // _vo == UseMarkWord -> use mark word from object header. 3302 VerifyRegionClosure(bool par, VerifyOption vo) 3303 : _par(par), 3304 _vo(vo), 3305 _failures(false) {} 3306 3307 bool failures() { 3308 return _failures; 3309 } 3310 3311 bool doHeapRegion(HeapRegion* r) { 3312 if (!r->continuesHumongous()) { 3313 bool failures = false; 3314 r->verify(_vo, &failures); 3315 if (failures) { 3316 _failures = true; 3317 } else { 3318 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo); 3319 r->object_iterate(¬_dead_yet_cl); 3320 if (_vo != VerifyOption_G1UseNextMarking) { 3321 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) { 3322 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] " 3323 "max_live_bytes "SIZE_FORMAT" " 3324 "< calculated "SIZE_FORMAT, 3325 r->bottom(), r->end(), 3326 r->max_live_bytes(), 3327 not_dead_yet_cl.live_bytes()); 3328 _failures = true; 3329 } 3330 } else { 3331 // When vo == UseNextMarking we cannot currently do a sanity 3332 // check on the live bytes as the calculation has not been 3333 // finalized yet. 3334 } 3335 } 3336 } 3337 return false; // stop the region iteration if we hit a failure 3338 } 3339 }; 3340 3341 // This is the task used for parallel verification of the heap regions 3342 3343 class G1ParVerifyTask: public AbstractGangTask { 3344 private: 3345 G1CollectedHeap* _g1h; 3346 VerifyOption _vo; 3347 bool _failures; 3348 3349 public: 3350 // _vo == UsePrevMarking -> use "prev" marking information, 3351 // _vo == UseNextMarking -> use "next" marking information, 3352 // _vo == UseMarkWord -> use mark word from object header. 3353 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) : 3354 AbstractGangTask("Parallel verify task"), 3355 _g1h(g1h), 3356 _vo(vo), 3357 _failures(false) { } 3358 3359 bool failures() { 3360 return _failures; 3361 } 3362 3363 void work(uint worker_id) { 3364 HandleMark hm; 3365 VerifyRegionClosure blk(true, _vo); 3366 _g1h->heap_region_par_iterate_chunked(&blk, worker_id, 3367 _g1h->workers()->active_workers(), 3368 HeapRegion::ParVerifyClaimValue); 3369 if (blk.failures()) { 3370 _failures = true; 3371 } 3372 } 3373 }; 3374 3375 void G1CollectedHeap::verify(bool silent, VerifyOption vo) { 3376 if (SafepointSynchronize::is_at_safepoint()) { 3377 assert(Thread::current()->is_VM_thread(), 3378 "Expected to be executed serially by the VM thread at this point"); 3379 3380 if (!silent) { gclog_or_tty->print("Roots "); } 3381 VerifyRootsClosure rootsCl(vo); 3382 VerifyKlassClosure klassCl(this, &rootsCl); 3383 3384 // We apply the relevant closures to all the oops in the 3385 // system dictionary, class loader data graph and the string table. 3386 // Don't verify the code cache here, since it's verified below. 3387 const int so = SO_AllClasses | SO_Strings; 3388 3389 // Need cleared claim bits for the strong roots processing 3390 ClassLoaderDataGraph::clear_claimed_marks(); 3391 3392 process_strong_roots(true, // activate StrongRootsScope 3393 ScanningOption(so), // roots scanning options 3394 &rootsCl, 3395 &klassCl 3396 ); 3397 3398 // Verify the nmethods in the code cache. 3399 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo); 3400 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl); 3401 CodeCache::blobs_do(&blobsCl); 3402 3403 bool failures = rootsCl.failures() || codeRootsCl.failures(); 3404 3405 if (vo != VerifyOption_G1UseMarkWord) { 3406 // If we're verifying during a full GC then the region sets 3407 // will have been torn down at the start of the GC. Therefore 3408 // verifying the region sets will fail. So we only verify 3409 // the region sets when not in a full GC. 3410 if (!silent) { gclog_or_tty->print("HeapRegionSets "); } 3411 verify_region_sets(); 3412 } 3413 3414 if (!silent) { gclog_or_tty->print("HeapRegions "); } 3415 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) { 3416 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue), 3417 "sanity check"); 3418 3419 G1ParVerifyTask task(this, vo); 3420 assert(UseDynamicNumberOfGCThreads || 3421 workers()->active_workers() == workers()->total_workers(), 3422 "If not dynamic should be using all the workers"); 3423 int n_workers = workers()->active_workers(); 3424 set_par_threads(n_workers); 3425 workers()->run_task(&task); 3426 set_par_threads(0); 3427 if (task.failures()) { 3428 failures = true; 3429 } 3430 3431 // Checks that the expected amount of parallel work was done. 3432 // The implication is that n_workers is > 0. 3433 assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue), 3434 "sanity check"); 3435 3436 reset_heap_region_claim_values(); 3437 3438 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue), 3439 "sanity check"); 3440 } else { 3441 VerifyRegionClosure blk(false, vo); 3442 heap_region_iterate(&blk); 3443 if (blk.failures()) { 3444 failures = true; 3445 } 3446 } 3447 if (!silent) gclog_or_tty->print("RemSet "); 3448 rem_set()->verify(); 3449 3450 if (G1StringDedup::is_enabled()) { 3451 if (!silent) gclog_or_tty->print("StrDedup "); 3452 G1StringDedup::verify(); 3453 } 3454 3455 if (failures) { 3456 gclog_or_tty->print_cr("Heap:"); 3457 // It helps to have the per-region information in the output to 3458 // help us track down what went wrong. This is why we call 3459 // print_extended_on() instead of print_on(). 3460 print_extended_on(gclog_or_tty); 3461 gclog_or_tty->cr(); 3462 #ifndef PRODUCT 3463 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) { 3464 concurrent_mark()->print_reachable("at-verification-failure", 3465 vo, false /* all */); 3466 } 3467 #endif 3468 gclog_or_tty->flush(); 3469 } 3470 guarantee(!failures, "there should not have been any failures"); 3471 } else { 3472 if (!silent) { 3473 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet"); 3474 if (G1StringDedup::is_enabled()) { 3475 gclog_or_tty->print(", StrDedup"); 3476 } 3477 gclog_or_tty->print(") "); 3478 } 3479 } 3480 } 3481 3482 void G1CollectedHeap::verify(bool silent) { 3483 verify(silent, VerifyOption_G1UsePrevMarking); 3484 } 3485 3486 double G1CollectedHeap::verify(bool guard, const char* msg) { 3487 double verify_time_ms = 0.0; 3488 3489 if (guard && total_collections() >= VerifyGCStartAt) { 3490 double verify_start = os::elapsedTime(); 3491 HandleMark hm; // Discard invalid handles created during verification 3492 prepare_for_verify(); 3493 Universe::verify(VerifyOption_G1UsePrevMarking, msg); 3494 verify_time_ms = (os::elapsedTime() - verify_start) * 1000; 3495 } 3496 3497 return verify_time_ms; 3498 } 3499 3500 void G1CollectedHeap::verify_before_gc() { 3501 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:"); 3502 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms); 3503 } 3504 3505 void G1CollectedHeap::verify_after_gc() { 3506 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:"); 3507 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms); 3508 } 3509 3510 class PrintRegionClosure: public HeapRegionClosure { 3511 outputStream* _st; 3512 public: 3513 PrintRegionClosure(outputStream* st) : _st(st) {} 3514 bool doHeapRegion(HeapRegion* r) { 3515 r->print_on(_st); 3516 return false; 3517 } 3518 }; 3519 3520 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 3521 const HeapRegion* hr, 3522 const VerifyOption vo) const { 3523 switch (vo) { 3524 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); 3525 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); 3526 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked(); 3527 default: ShouldNotReachHere(); 3528 } 3529 return false; // keep some compilers happy 3530 } 3531 3532 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 3533 const VerifyOption vo) const { 3534 switch (vo) { 3535 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); 3536 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); 3537 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked(); 3538 default: ShouldNotReachHere(); 3539 } 3540 return false; // keep some compilers happy 3541 } 3542 3543 void G1CollectedHeap::print_on(outputStream* st) const { 3544 st->print(" %-20s", "garbage-first heap"); 3545 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 3546 capacity()/K, used_unlocked()/K); 3547 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")", 3548 _g1_storage.low_boundary(), 3549 _g1_storage.high(), 3550 _g1_storage.high_boundary()); 3551 st->cr(); 3552 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); 3553 uint young_regions = _young_list->length(); 3554 st->print("%u young (" SIZE_FORMAT "K), ", young_regions, 3555 (size_t) young_regions * HeapRegion::GrainBytes / K); 3556 uint survivor_regions = g1_policy()->recorded_survivor_regions(); 3557 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, 3558 (size_t) survivor_regions * HeapRegion::GrainBytes / K); 3559 st->cr(); 3560 MetaspaceAux::print_on(st); 3561 } 3562 3563 void G1CollectedHeap::print_extended_on(outputStream* st) const { 3564 print_on(st); 3565 3566 // Print the per-region information. 3567 st->cr(); 3568 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), " 3569 "HS=humongous(starts), HC=humongous(continues), " 3570 "CS=collection set, F=free, TS=gc time stamp, " 3571 "PTAMS=previous top-at-mark-start, " 3572 "NTAMS=next top-at-mark-start)"); 3573 PrintRegionClosure blk(st); 3574 heap_region_iterate(&blk); 3575 } 3576 3577 void G1CollectedHeap::print_on_error(outputStream* st) const { 3578 this->CollectedHeap::print_on_error(st); 3579 3580 if (_cm != NULL) { 3581 st->cr(); 3582 _cm->print_on_error(st); 3583 } 3584 } 3585 3586 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const { 3587 if (G1CollectedHeap::use_parallel_gc_threads()) { 3588 workers()->print_worker_threads_on(st); 3589 } 3590 _cmThread->print_on(st); 3591 st->cr(); 3592 _cm->print_worker_threads_on(st); 3593 _cg1r->print_worker_threads_on(st); 3594 if (G1StringDedup::is_enabled()) { 3595 G1StringDedup::print_worker_threads_on(st); 3596 } 3597 } 3598 3599 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { 3600 if (G1CollectedHeap::use_parallel_gc_threads()) { 3601 workers()->threads_do(tc); 3602 } 3603 tc->do_thread(_cmThread); 3604 _cg1r->threads_do(tc); 3605 if (G1StringDedup::is_enabled()) { 3606 G1StringDedup::threads_do(tc); 3607 } 3608 } 3609 3610 void G1CollectedHeap::print_tracing_info() const { 3611 // We'll overload this to mean "trace GC pause statistics." 3612 if (TraceYoungGenTime || TraceOldGenTime) { 3613 // The "G1CollectorPolicy" is keeping track of these stats, so delegate 3614 // to that. 3615 g1_policy()->print_tracing_info(); 3616 } 3617 if (G1SummarizeRSetStats) { 3618 g1_rem_set()->print_summary_info(); 3619 } 3620 if (G1SummarizeConcMark) { 3621 concurrent_mark()->print_summary_info(); 3622 } 3623 g1_policy()->print_yg_surv_rate_info(); 3624 SpecializationStats::print(); 3625 } 3626 3627 #ifndef PRODUCT 3628 // Helpful for debugging RSet issues. 3629 3630 class PrintRSetsClosure : public HeapRegionClosure { 3631 private: 3632 const char* _msg; 3633 size_t _occupied_sum; 3634 3635 public: 3636 bool doHeapRegion(HeapRegion* r) { 3637 HeapRegionRemSet* hrrs = r->rem_set(); 3638 size_t occupied = hrrs->occupied(); 3639 _occupied_sum += occupied; 3640 3641 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT, 3642 HR_FORMAT_PARAMS(r)); 3643 if (occupied == 0) { 3644 gclog_or_tty->print_cr(" RSet is empty"); 3645 } else { 3646 hrrs->print(); 3647 } 3648 gclog_or_tty->print_cr("----------"); 3649 return false; 3650 } 3651 3652 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { 3653 gclog_or_tty->cr(); 3654 gclog_or_tty->print_cr("========================================"); 3655 gclog_or_tty->print_cr("%s", msg); 3656 gclog_or_tty->cr(); 3657 } 3658 3659 ~PrintRSetsClosure() { 3660 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum); 3661 gclog_or_tty->print_cr("========================================"); 3662 gclog_or_tty->cr(); 3663 } 3664 }; 3665 3666 void G1CollectedHeap::print_cset_rsets() { 3667 PrintRSetsClosure cl("Printing CSet RSets"); 3668 collection_set_iterate(&cl); 3669 } 3670 3671 void G1CollectedHeap::print_all_rsets() { 3672 PrintRSetsClosure cl("Printing All RSets");; 3673 heap_region_iterate(&cl); 3674 } 3675 #endif // PRODUCT 3676 3677 G1CollectedHeap* G1CollectedHeap::heap() { 3678 assert(_sh->kind() == CollectedHeap::G1CollectedHeap, 3679 "not a garbage-first heap"); 3680 return _g1h; 3681 } 3682 3683 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) { 3684 // always_do_update_barrier = false; 3685 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 3686 // Fill TLAB's and such 3687 accumulate_statistics_all_tlabs(); 3688 ensure_parsability(true); 3689 3690 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) && 3691 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) { 3692 g1_rem_set()->print_periodic_summary_info("Before GC RS summary"); 3693 } 3694 } 3695 3696 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) { 3697 3698 if (G1SummarizeRSetStats && 3699 (G1SummarizeRSetStatsPeriod > 0) && 3700 // we are at the end of the GC. Total collections has already been increased. 3701 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) { 3702 g1_rem_set()->print_periodic_summary_info("After GC RS summary"); 3703 } 3704 3705 // FIXME: what is this about? 3706 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" 3707 // is set. 3708 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(), 3709 "derived pointer present")); 3710 // always_do_update_barrier = true; 3711 3712 resize_all_tlabs(); 3713 3714 // We have just completed a GC. Update the soft reference 3715 // policy with the new heap occupancy 3716 Universe::update_heap_info_at_gc(); 3717 } 3718 3719 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, 3720 unsigned int gc_count_before, 3721 bool* succeeded, 3722 GCCause::Cause gc_cause) { 3723 assert_heap_not_locked_and_not_at_safepoint(); 3724 g1_policy()->record_stop_world_start(); 3725 VM_G1IncCollectionPause op(gc_count_before, 3726 word_size, 3727 false, /* should_initiate_conc_mark */ 3728 g1_policy()->max_pause_time_ms(), 3729 gc_cause); 3730 VMThread::execute(&op); 3731 3732 HeapWord* result = op.result(); 3733 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded(); 3734 assert(result == NULL || ret_succeeded, 3735 "the result should be NULL if the VM did not succeed"); 3736 *succeeded = ret_succeeded; 3737 3738 assert_heap_not_locked(); 3739 return result; 3740 } 3741 3742 void 3743 G1CollectedHeap::doConcurrentMark() { 3744 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); 3745 if (!_cmThread->in_progress()) { 3746 _cmThread->set_started(); 3747 CGC_lock->notify(); 3748 } 3749 } 3750 3751 size_t G1CollectedHeap::pending_card_num() { 3752 size_t extra_cards = 0; 3753 JavaThread *curr = Threads::first(); 3754 while (curr != NULL) { 3755 DirtyCardQueue& dcq = curr->dirty_card_queue(); 3756 extra_cards += dcq.size(); 3757 curr = curr->next(); 3758 } 3759 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 3760 size_t buffer_size = dcqs.buffer_size(); 3761 size_t buffer_num = dcqs.completed_buffers_num(); 3762 3763 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes 3764 // in bytes - not the number of 'entries'. We need to convert 3765 // into a number of cards. 3766 return (buffer_size * buffer_num + extra_cards) / oopSize; 3767 } 3768 3769 size_t G1CollectedHeap::cards_scanned() { 3770 return g1_rem_set()->cardsScanned(); 3771 } 3772 3773 void 3774 G1CollectedHeap::setup_surviving_young_words() { 3775 assert(_surviving_young_words == NULL, "pre-condition"); 3776 uint array_length = g1_policy()->young_cset_region_length(); 3777 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC); 3778 if (_surviving_young_words == NULL) { 3779 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR, 3780 "Not enough space for young surv words summary."); 3781 } 3782 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t)); 3783 #ifdef ASSERT 3784 for (uint i = 0; i < array_length; ++i) { 3785 assert( _surviving_young_words[i] == 0, "memset above" ); 3786 } 3787 #endif // !ASSERT 3788 } 3789 3790 void 3791 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) { 3792 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); 3793 uint array_length = g1_policy()->young_cset_region_length(); 3794 for (uint i = 0; i < array_length; ++i) { 3795 _surviving_young_words[i] += surv_young_words[i]; 3796 } 3797 } 3798 3799 void 3800 G1CollectedHeap::cleanup_surviving_young_words() { 3801 guarantee( _surviving_young_words != NULL, "pre-condition" ); 3802 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words, mtGC); 3803 _surviving_young_words = NULL; 3804 } 3805 3806 #ifdef ASSERT 3807 class VerifyCSetClosure: public HeapRegionClosure { 3808 public: 3809 bool doHeapRegion(HeapRegion* hr) { 3810 // Here we check that the CSet region's RSet is ready for parallel 3811 // iteration. The fields that we'll verify are only manipulated 3812 // when the region is part of a CSet and is collected. Afterwards, 3813 // we reset these fields when we clear the region's RSet (when the 3814 // region is freed) so they are ready when the region is 3815 // re-allocated. The only exception to this is if there's an 3816 // evacuation failure and instead of freeing the region we leave 3817 // it in the heap. In that case, we reset these fields during 3818 // evacuation failure handling. 3819 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification"); 3820 3821 // Here's a good place to add any other checks we'd like to 3822 // perform on CSet regions. 3823 return false; 3824 } 3825 }; 3826 #endif // ASSERT 3827 3828 #if TASKQUEUE_STATS 3829 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) { 3830 st->print_raw_cr("GC Task Stats"); 3831 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); 3832 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); 3833 } 3834 3835 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const { 3836 print_taskqueue_stats_hdr(st); 3837 3838 TaskQueueStats totals; 3839 const int n = workers() != NULL ? workers()->total_workers() : 1; 3840 for (int i = 0; i < n; ++i) { 3841 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr(); 3842 totals += task_queue(i)->stats; 3843 } 3844 st->print_raw("tot "); totals.print(st); st->cr(); 3845 3846 DEBUG_ONLY(totals.verify()); 3847 } 3848 3849 void G1CollectedHeap::reset_taskqueue_stats() { 3850 const int n = workers() != NULL ? workers()->total_workers() : 1; 3851 for (int i = 0; i < n; ++i) { 3852 task_queue(i)->stats.reset(); 3853 } 3854 } 3855 #endif // TASKQUEUE_STATS 3856 3857 void G1CollectedHeap::log_gc_header() { 3858 if (!G1Log::fine()) { 3859 return; 3860 } 3861 3862 gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id()); 3863 3864 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause()) 3865 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)") 3866 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : ""); 3867 3868 gclog_or_tty->print("[%s", (const char*)gc_cause_str); 3869 } 3870 3871 void G1CollectedHeap::log_gc_footer(double pause_time_sec) { 3872 if (!G1Log::fine()) { 3873 return; 3874 } 3875 3876 if (G1Log::finer()) { 3877 if (evacuation_failed()) { 3878 gclog_or_tty->print(" (to-space exhausted)"); 3879 } 3880 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec); 3881 g1_policy()->phase_times()->note_gc_end(); 3882 g1_policy()->phase_times()->print(pause_time_sec); 3883 g1_policy()->print_detailed_heap_transition(); 3884 } else { 3885 if (evacuation_failed()) { 3886 gclog_or_tty->print("--"); 3887 } 3888 g1_policy()->print_heap_transition(); 3889 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec); 3890 } 3891 gclog_or_tty->flush(); 3892 } 3893 3894 bool 3895 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { 3896 assert_at_safepoint(true /* should_be_vm_thread */); 3897 guarantee(!is_gc_active(), "collection is not reentrant"); 3898 3899 if (GC_locker::check_active_before_gc()) { 3900 return false; 3901 } 3902 3903 _gc_timer_stw->register_gc_start(); 3904 3905 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start()); 3906 3907 SvcGCMarker sgcm(SvcGCMarker::MINOR); 3908 ResourceMark rm; 3909 3910 print_heap_before_gc(); 3911 trace_heap_before_gc(_gc_tracer_stw); 3912 3913 verify_region_sets_optional(); 3914 verify_dirty_young_regions(); 3915 3916 // This call will decide whether this pause is an initial-mark 3917 // pause. If it is, during_initial_mark_pause() will return true 3918 // for the duration of this pause. 3919 g1_policy()->decide_on_conc_mark_initiation(); 3920 3921 // We do not allow initial-mark to be piggy-backed on a mixed GC. 3922 assert(!g1_policy()->during_initial_mark_pause() || 3923 g1_policy()->gcs_are_young(), "sanity"); 3924 3925 // We also do not allow mixed GCs during marking. 3926 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity"); 3927 3928 // Record whether this pause is an initial mark. When the current 3929 // thread has completed its logging output and it's safe to signal 3930 // the CM thread, the flag's value in the policy has been reset. 3931 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause(); 3932 3933 // Inner scope for scope based logging, timers, and stats collection 3934 { 3935 EvacuationInfo evacuation_info; 3936 3937 if (g1_policy()->during_initial_mark_pause()) { 3938 // We are about to start a marking cycle, so we increment the 3939 // full collection counter. 3940 increment_old_marking_cycles_started(); 3941 register_concurrent_cycle_start(_gc_timer_stw->gc_start()); 3942 } 3943 3944 _gc_tracer_stw->report_yc_type(yc_type()); 3945 3946 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty); 3947 3948 int active_workers = (G1CollectedHeap::use_parallel_gc_threads() ? 3949 workers()->active_workers() : 1); 3950 double pause_start_sec = os::elapsedTime(); 3951 g1_policy()->phase_times()->note_gc_start(active_workers); 3952 log_gc_header(); 3953 3954 TraceCollectorStats tcs(g1mm()->incremental_collection_counters()); 3955 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause()); 3956 3957 // If the secondary_free_list is not empty, append it to the 3958 // free_list. No need to wait for the cleanup operation to finish; 3959 // the region allocation code will check the secondary_free_list 3960 // and wait if necessary. If the G1StressConcRegionFreeing flag is 3961 // set, skip this step so that the region allocation code has to 3962 // get entries from the secondary_free_list. 3963 if (!G1StressConcRegionFreeing) { 3964 append_secondary_free_list_if_not_empty_with_lock(); 3965 } 3966 3967 assert(check_young_list_well_formed(), "young list should be well formed"); 3968 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue), 3969 "sanity check"); 3970 3971 // Don't dynamically change the number of GC threads this early. A value of 3972 // 0 is used to indicate serial work. When parallel work is done, 3973 // it will be set. 3974 3975 { // Call to jvmpi::post_class_unload_events must occur outside of active GC 3976 IsGCActiveMark x; 3977 3978 gc_prologue(false); 3979 increment_total_collections(false /* full gc */); 3980 increment_gc_time_stamp(); 3981 3982 verify_before_gc(); 3983 check_bitmaps("GC Start"); 3984 3985 COMPILER2_PRESENT(DerivedPointerTable::clear()); 3986 3987 // Please see comment in g1CollectedHeap.hpp and 3988 // G1CollectedHeap::ref_processing_init() to see how 3989 // reference processing currently works in G1. 3990 3991 // Enable discovery in the STW reference processor 3992 ref_processor_stw()->enable_discovery(true /*verify_disabled*/, 3993 true /*verify_no_refs*/); 3994 3995 { 3996 // We want to temporarily turn off discovery by the 3997 // CM ref processor, if necessary, and turn it back on 3998 // on again later if we do. Using a scoped 3999 // NoRefDiscovery object will do this. 4000 NoRefDiscovery no_cm_discovery(ref_processor_cm()); 4001 4002 // Forget the current alloc region (we might even choose it to be part 4003 // of the collection set!). 4004 release_mutator_alloc_region(); 4005 4006 // We should call this after we retire the mutator alloc 4007 // region(s) so that all the ALLOC / RETIRE events are generated 4008 // before the start GC event. 4009 _hr_printer.start_gc(false /* full */, (size_t) total_collections()); 4010 4011 // This timing is only used by the ergonomics to handle our pause target. 4012 // It is unclear why this should not include the full pause. We will 4013 // investigate this in CR 7178365. 4014 // 4015 // Preserving the old comment here if that helps the investigation: 4016 // 4017 // The elapsed time induced by the start time below deliberately elides 4018 // the possible verification above. 4019 double sample_start_time_sec = os::elapsedTime(); 4020 4021 #if YOUNG_LIST_VERBOSE 4022 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:"); 4023 _young_list->print(); 4024 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 4025 #endif // YOUNG_LIST_VERBOSE 4026 4027 g1_policy()->record_collection_pause_start(sample_start_time_sec); 4028 4029 double scan_wait_start = os::elapsedTime(); 4030 // We have to wait until the CM threads finish scanning the 4031 // root regions as it's the only way to ensure that all the 4032 // objects on them have been correctly scanned before we start 4033 // moving them during the GC. 4034 bool waited = _cm->root_regions()->wait_until_scan_finished(); 4035 double wait_time_ms = 0.0; 4036 if (waited) { 4037 double scan_wait_end = os::elapsedTime(); 4038 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0; 4039 } 4040 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms); 4041 4042 #if YOUNG_LIST_VERBOSE 4043 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:"); 4044 _young_list->print(); 4045 #endif // YOUNG_LIST_VERBOSE 4046 4047 if (g1_policy()->during_initial_mark_pause()) { 4048 concurrent_mark()->checkpointRootsInitialPre(); 4049 } 4050 4051 #if YOUNG_LIST_VERBOSE 4052 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:"); 4053 _young_list->print(); 4054 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 4055 #endif // YOUNG_LIST_VERBOSE 4056 4057 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info); 4058 4059 _cm->note_start_of_gc(); 4060 // We should not verify the per-thread SATB buffers given that 4061 // we have not filtered them yet (we'll do so during the 4062 // GC). We also call this after finalize_cset() to 4063 // ensure that the CSet has been finalized. 4064 _cm->verify_no_cset_oops(true /* verify_stacks */, 4065 true /* verify_enqueued_buffers */, 4066 false /* verify_thread_buffers */, 4067 true /* verify_fingers */); 4068 4069 if (_hr_printer.is_active()) { 4070 HeapRegion* hr = g1_policy()->collection_set(); 4071 while (hr != NULL) { 4072 G1HRPrinter::RegionType type; 4073 if (!hr->is_young()) { 4074 type = G1HRPrinter::Old; 4075 } else if (hr->is_survivor()) { 4076 type = G1HRPrinter::Survivor; 4077 } else { 4078 type = G1HRPrinter::Eden; 4079 } 4080 _hr_printer.cset(hr); 4081 hr = hr->next_in_collection_set(); 4082 } 4083 } 4084 4085 #ifdef ASSERT 4086 VerifyCSetClosure cl; 4087 collection_set_iterate(&cl); 4088 #endif // ASSERT 4089 4090 setup_surviving_young_words(); 4091 4092 // Initialize the GC alloc regions. 4093 init_gc_alloc_regions(evacuation_info); 4094 4095 // Actually do the work... 4096 evacuate_collection_set(evacuation_info); 4097 4098 // We do this to mainly verify the per-thread SATB buffers 4099 // (which have been filtered by now) since we didn't verify 4100 // them earlier. No point in re-checking the stacks / enqueued 4101 // buffers given that the CSet has not changed since last time 4102 // we checked. 4103 _cm->verify_no_cset_oops(false /* verify_stacks */, 4104 false /* verify_enqueued_buffers */, 4105 true /* verify_thread_buffers */, 4106 true /* verify_fingers */); 4107 4108 free_collection_set(g1_policy()->collection_set(), evacuation_info); 4109 g1_policy()->clear_collection_set(); 4110 4111 cleanup_surviving_young_words(); 4112 4113 // Start a new incremental collection set for the next pause. 4114 g1_policy()->start_incremental_cset_building(); 4115 4116 clear_cset_fast_test(); 4117 4118 _young_list->reset_sampled_info(); 4119 4120 // Don't check the whole heap at this point as the 4121 // GC alloc regions from this pause have been tagged 4122 // as survivors and moved on to the survivor list. 4123 // Survivor regions will fail the !is_young() check. 4124 assert(check_young_list_empty(false /* check_heap */), 4125 "young list should be empty"); 4126 4127 #if YOUNG_LIST_VERBOSE 4128 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:"); 4129 _young_list->print(); 4130 #endif // YOUNG_LIST_VERBOSE 4131 4132 g1_policy()->record_survivor_regions(_young_list->survivor_length(), 4133 _young_list->first_survivor_region(), 4134 _young_list->last_survivor_region()); 4135 4136 _young_list->reset_auxilary_lists(); 4137 4138 if (evacuation_failed()) { 4139 _summary_bytes_used = recalculate_used(); 4140 uint n_queues = MAX2((int)ParallelGCThreads, 1); 4141 for (uint i = 0; i < n_queues; i++) { 4142 if (_evacuation_failed_info_array[i].has_failed()) { 4143 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]); 4144 } 4145 } 4146 } else { 4147 // The "used" of the the collection set have already been subtracted 4148 // when they were freed. Add in the bytes evacuated. 4149 _summary_bytes_used += g1_policy()->bytes_copied_during_gc(); 4150 } 4151 4152 if (g1_policy()->during_initial_mark_pause()) { 4153 // We have to do this before we notify the CM threads that 4154 // they can start working to make sure that all the 4155 // appropriate initialization is done on the CM object. 4156 concurrent_mark()->checkpointRootsInitialPost(); 4157 set_marking_started(); 4158 // Note that we don't actually trigger the CM thread at 4159 // this point. We do that later when we're sure that 4160 // the current thread has completed its logging output. 4161 } 4162 4163 allocate_dummy_regions(); 4164 4165 #if YOUNG_LIST_VERBOSE 4166 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:"); 4167 _young_list->print(); 4168 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 4169 #endif // YOUNG_LIST_VERBOSE 4170 4171 init_mutator_alloc_region(); 4172 4173 { 4174 size_t expand_bytes = g1_policy()->expansion_amount(); 4175 if (expand_bytes > 0) { 4176 size_t bytes_before = capacity(); 4177 // No need for an ergo verbose message here, 4178 // expansion_amount() does this when it returns a value > 0. 4179 if (!expand(expand_bytes)) { 4180 // We failed to expand the heap so let's verify that 4181 // committed/uncommitted amount match the backing store 4182 assert(capacity() == _g1_storage.committed_size(), "committed size mismatch"); 4183 assert(max_capacity() == _g1_storage.reserved_size(), "reserved size mismatch"); 4184 } 4185 } 4186 } 4187 4188 // We redo the verification but now wrt to the new CSet which 4189 // has just got initialized after the previous CSet was freed. 4190 _cm->verify_no_cset_oops(true /* verify_stacks */, 4191 true /* verify_enqueued_buffers */, 4192 true /* verify_thread_buffers */, 4193 true /* verify_fingers */); 4194 _cm->note_end_of_gc(); 4195 4196 // This timing is only used by the ergonomics to handle our pause target. 4197 // It is unclear why this should not include the full pause. We will 4198 // investigate this in CR 7178365. 4199 double sample_end_time_sec = os::elapsedTime(); 4200 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; 4201 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info); 4202 4203 MemoryService::track_memory_usage(); 4204 4205 // In prepare_for_verify() below we'll need to scan the deferred 4206 // update buffers to bring the RSets up-to-date if 4207 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning 4208 // the update buffers we'll probably need to scan cards on the 4209 // regions we just allocated to (i.e., the GC alloc 4210 // regions). However, during the last GC we called 4211 // set_saved_mark() on all the GC alloc regions, so card 4212 // scanning might skip the [saved_mark_word()...top()] area of 4213 // those regions (i.e., the area we allocated objects into 4214 // during the last GC). But it shouldn't. Given that 4215 // saved_mark_word() is conditional on whether the GC time stamp 4216 // on the region is current or not, by incrementing the GC time 4217 // stamp here we invalidate all the GC time stamps on all the 4218 // regions and saved_mark_word() will simply return top() for 4219 // all the regions. This is a nicer way of ensuring this rather 4220 // than iterating over the regions and fixing them. In fact, the 4221 // GC time stamp increment here also ensures that 4222 // saved_mark_word() will return top() between pauses, i.e., 4223 // during concurrent refinement. So we don't need the 4224 // is_gc_active() check to decided which top to use when 4225 // scanning cards (see CR 7039627). 4226 increment_gc_time_stamp(); 4227 4228 verify_after_gc(); 4229 check_bitmaps("GC End"); 4230 4231 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 4232 ref_processor_stw()->verify_no_references_recorded(); 4233 4234 // CM reference discovery will be re-enabled if necessary. 4235 } 4236 4237 // We should do this after we potentially expand the heap so 4238 // that all the COMMIT events are generated before the end GC 4239 // event, and after we retire the GC alloc regions so that all 4240 // RETIRE events are generated before the end GC event. 4241 _hr_printer.end_gc(false /* full */, (size_t) total_collections()); 4242 4243 if (mark_in_progress()) { 4244 concurrent_mark()->update_g1_committed(); 4245 } 4246 4247 #ifdef TRACESPINNING 4248 ParallelTaskTerminator::print_termination_counts(); 4249 #endif 4250 4251 gc_epilogue(false); 4252 } 4253 4254 // Print the remainder of the GC log output. 4255 log_gc_footer(os::elapsedTime() - pause_start_sec); 4256 4257 // It is not yet to safe to tell the concurrent mark to 4258 // start as we have some optional output below. We don't want the 4259 // output from the concurrent mark thread interfering with this 4260 // logging output either. 4261 4262 _hrs.verify_optional(); 4263 verify_region_sets_optional(); 4264 4265 TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats()); 4266 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); 4267 4268 print_heap_after_gc(); 4269 trace_heap_after_gc(_gc_tracer_stw); 4270 4271 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 4272 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 4273 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 4274 // before any GC notifications are raised. 4275 g1mm()->update_sizes(); 4276 4277 _gc_tracer_stw->report_evacuation_info(&evacuation_info); 4278 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold()); 4279 _gc_timer_stw->register_gc_end(); 4280 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions()); 4281 } 4282 // It should now be safe to tell the concurrent mark thread to start 4283 // without its logging output interfering with the logging output 4284 // that came from the pause. 4285 4286 if (should_start_conc_mark) { 4287 // CAUTION: after the doConcurrentMark() call below, 4288 // the concurrent marking thread(s) could be running 4289 // concurrently with us. Make sure that anything after 4290 // this point does not assume that we are the only GC thread 4291 // running. Note: of course, the actual marking work will 4292 // not start until the safepoint itself is released in 4293 // SuspendibleThreadSet::desynchronize(). 4294 doConcurrentMark(); 4295 } 4296 4297 return true; 4298 } 4299 4300 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose) 4301 { 4302 size_t gclab_word_size; 4303 switch (purpose) { 4304 case GCAllocForSurvived: 4305 gclab_word_size = _survivor_plab_stats.desired_plab_sz(); 4306 break; 4307 case GCAllocForTenured: 4308 gclab_word_size = _old_plab_stats.desired_plab_sz(); 4309 break; 4310 default: 4311 assert(false, "unknown GCAllocPurpose"); 4312 gclab_word_size = _old_plab_stats.desired_plab_sz(); 4313 break; 4314 } 4315 4316 // Prevent humongous PLAB sizes for two reasons: 4317 // * PLABs are allocated using a similar paths as oops, but should 4318 // never be in a humongous region 4319 // * Allowing humongous PLABs needlessly churns the region free lists 4320 return MIN2(_humongous_object_threshold_in_words, gclab_word_size); 4321 } 4322 4323 void G1CollectedHeap::init_mutator_alloc_region() { 4324 assert(_mutator_alloc_region.get() == NULL, "pre-condition"); 4325 _mutator_alloc_region.init(); 4326 } 4327 4328 void G1CollectedHeap::release_mutator_alloc_region() { 4329 _mutator_alloc_region.release(); 4330 assert(_mutator_alloc_region.get() == NULL, "post-condition"); 4331 } 4332 4333 void G1CollectedHeap::init_gc_alloc_regions(EvacuationInfo& evacuation_info) { 4334 assert_at_safepoint(true /* should_be_vm_thread */); 4335 4336 _survivor_gc_alloc_region.init(); 4337 _old_gc_alloc_region.init(); 4338 HeapRegion* retained_region = _retained_old_gc_alloc_region; 4339 _retained_old_gc_alloc_region = NULL; 4340 4341 // We will discard the current GC alloc region if: 4342 // a) it's in the collection set (it can happen!), 4343 // b) it's already full (no point in using it), 4344 // c) it's empty (this means that it was emptied during 4345 // a cleanup and it should be on the free list now), or 4346 // d) it's humongous (this means that it was emptied 4347 // during a cleanup and was added to the free list, but 4348 // has been subsequently used to allocate a humongous 4349 // object that may be less than the region size). 4350 if (retained_region != NULL && 4351 !retained_region->in_collection_set() && 4352 !(retained_region->top() == retained_region->end()) && 4353 !retained_region->is_empty() && 4354 !retained_region->isHumongous()) { 4355 retained_region->set_saved_mark(); 4356 // The retained region was added to the old region set when it was 4357 // retired. We have to remove it now, since we don't allow regions 4358 // we allocate to in the region sets. We'll re-add it later, when 4359 // it's retired again. 4360 _old_set.remove(retained_region); 4361 bool during_im = g1_policy()->during_initial_mark_pause(); 4362 retained_region->note_start_of_copying(during_im); 4363 _old_gc_alloc_region.set(retained_region); 4364 _hr_printer.reuse(retained_region); 4365 evacuation_info.set_alloc_regions_used_before(retained_region->used()); 4366 } 4367 } 4368 4369 void G1CollectedHeap::release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info) { 4370 evacuation_info.set_allocation_regions(_survivor_gc_alloc_region.count() + 4371 _old_gc_alloc_region.count()); 4372 _survivor_gc_alloc_region.release(); 4373 // If we have an old GC alloc region to release, we'll save it in 4374 // _retained_old_gc_alloc_region. If we don't 4375 // _retained_old_gc_alloc_region will become NULL. This is what we 4376 // want either way so no reason to check explicitly for either 4377 // condition. 4378 _retained_old_gc_alloc_region = _old_gc_alloc_region.release(); 4379 4380 if (ResizePLAB) { 4381 _survivor_plab_stats.adjust_desired_plab_sz(no_of_gc_workers); 4382 _old_plab_stats.adjust_desired_plab_sz(no_of_gc_workers); 4383 } 4384 } 4385 4386 void G1CollectedHeap::abandon_gc_alloc_regions() { 4387 assert(_survivor_gc_alloc_region.get() == NULL, "pre-condition"); 4388 assert(_old_gc_alloc_region.get() == NULL, "pre-condition"); 4389 _retained_old_gc_alloc_region = NULL; 4390 } 4391 4392 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) { 4393 _drain_in_progress = false; 4394 set_evac_failure_closure(cl); 4395 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true); 4396 } 4397 4398 void G1CollectedHeap::finalize_for_evac_failure() { 4399 assert(_evac_failure_scan_stack != NULL && 4400 _evac_failure_scan_stack->length() == 0, 4401 "Postcondition"); 4402 assert(!_drain_in_progress, "Postcondition"); 4403 delete _evac_failure_scan_stack; 4404 _evac_failure_scan_stack = NULL; 4405 } 4406 4407 void G1CollectedHeap::remove_self_forwarding_pointers() { 4408 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity"); 4409 4410 double remove_self_forwards_start = os::elapsedTime(); 4411 4412 G1ParRemoveSelfForwardPtrsTask rsfp_task(this); 4413 4414 if (G1CollectedHeap::use_parallel_gc_threads()) { 4415 set_par_threads(); 4416 workers()->run_task(&rsfp_task); 4417 set_par_threads(0); 4418 } else { 4419 rsfp_task.work(0); 4420 } 4421 4422 assert(check_cset_heap_region_claim_values(HeapRegion::ParEvacFailureClaimValue), "sanity"); 4423 4424 // Reset the claim values in the regions in the collection set. 4425 reset_cset_heap_region_claim_values(); 4426 4427 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity"); 4428 4429 // Now restore saved marks, if any. 4430 assert(_objs_with_preserved_marks.size() == 4431 _preserved_marks_of_objs.size(), "Both or none."); 4432 while (!_objs_with_preserved_marks.is_empty()) { 4433 oop obj = _objs_with_preserved_marks.pop(); 4434 markOop m = _preserved_marks_of_objs.pop(); 4435 obj->set_mark(m); 4436 } 4437 _objs_with_preserved_marks.clear(true); 4438 _preserved_marks_of_objs.clear(true); 4439 4440 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0); 4441 } 4442 4443 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) { 4444 _evac_failure_scan_stack->push(obj); 4445 } 4446 4447 void G1CollectedHeap::drain_evac_failure_scan_stack() { 4448 assert(_evac_failure_scan_stack != NULL, "precondition"); 4449 4450 while (_evac_failure_scan_stack->length() > 0) { 4451 oop obj = _evac_failure_scan_stack->pop(); 4452 _evac_failure_closure->set_region(heap_region_containing(obj)); 4453 obj->oop_iterate_backwards(_evac_failure_closure); 4454 } 4455 } 4456 4457 oop 4458 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state, 4459 oop old) { 4460 assert(obj_in_cs(old), 4461 err_msg("obj: "PTR_FORMAT" should still be in the CSet", 4462 (HeapWord*) old)); 4463 markOop m = old->mark(); 4464 oop forward_ptr = old->forward_to_atomic(old); 4465 if (forward_ptr == NULL) { 4466 // Forward-to-self succeeded. 4467 assert(_par_scan_state != NULL, "par scan state"); 4468 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure(); 4469 uint queue_num = _par_scan_state->queue_num(); 4470 4471 _evacuation_failed = true; 4472 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size()); 4473 if (_evac_failure_closure != cl) { 4474 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag); 4475 assert(!_drain_in_progress, 4476 "Should only be true while someone holds the lock."); 4477 // Set the global evac-failure closure to the current thread's. 4478 assert(_evac_failure_closure == NULL, "Or locking has failed."); 4479 set_evac_failure_closure(cl); 4480 // Now do the common part. 4481 handle_evacuation_failure_common(old, m); 4482 // Reset to NULL. 4483 set_evac_failure_closure(NULL); 4484 } else { 4485 // The lock is already held, and this is recursive. 4486 assert(_drain_in_progress, "This should only be the recursive case."); 4487 handle_evacuation_failure_common(old, m); 4488 } 4489 return old; 4490 } else { 4491 // Forward-to-self failed. Either someone else managed to allocate 4492 // space for this object (old != forward_ptr) or they beat us in 4493 // self-forwarding it (old == forward_ptr). 4494 assert(old == forward_ptr || !obj_in_cs(forward_ptr), 4495 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" " 4496 "should not be in the CSet", 4497 (HeapWord*) old, (HeapWord*) forward_ptr)); 4498 return forward_ptr; 4499 } 4500 } 4501 4502 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) { 4503 preserve_mark_if_necessary(old, m); 4504 4505 HeapRegion* r = heap_region_containing(old); 4506 if (!r->evacuation_failed()) { 4507 r->set_evacuation_failed(true); 4508 _hr_printer.evac_failure(r); 4509 } 4510 4511 push_on_evac_failure_scan_stack(old); 4512 4513 if (!_drain_in_progress) { 4514 // prevent recursion in copy_to_survivor_space() 4515 _drain_in_progress = true; 4516 drain_evac_failure_scan_stack(); 4517 _drain_in_progress = false; 4518 } 4519 } 4520 4521 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) { 4522 assert(evacuation_failed(), "Oversaving!"); 4523 // We want to call the "for_promotion_failure" version only in the 4524 // case of a promotion failure. 4525 if (m->must_be_preserved_for_promotion_failure(obj)) { 4526 _objs_with_preserved_marks.push(obj); 4527 _preserved_marks_of_objs.push(m); 4528 } 4529 } 4530 4531 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose, 4532 size_t word_size) { 4533 if (purpose == GCAllocForSurvived) { 4534 HeapWord* result = survivor_attempt_allocation(word_size); 4535 if (result != NULL) { 4536 return result; 4537 } else { 4538 // Let's try to allocate in the old gen in case we can fit the 4539 // object there. 4540 return old_attempt_allocation(word_size); 4541 } 4542 } else { 4543 assert(purpose == GCAllocForTenured, "sanity"); 4544 HeapWord* result = old_attempt_allocation(word_size); 4545 if (result != NULL) { 4546 return result; 4547 } else { 4548 // Let's try to allocate in the survivors in case we can fit the 4549 // object there. 4550 return survivor_attempt_allocation(word_size); 4551 } 4552 } 4553 4554 ShouldNotReachHere(); 4555 // Trying to keep some compilers happy. 4556 return NULL; 4557 } 4558 4559 G1ParGCAllocBuffer::G1ParGCAllocBuffer(size_t gclab_word_size) : 4560 ParGCAllocBuffer(gclab_word_size), _retired(true) { } 4561 4562 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num, ReferenceProcessor* rp) 4563 : _g1h(g1h), 4564 _refs(g1h->task_queue(queue_num)), 4565 _dcq(&g1h->dirty_card_queue_set()), 4566 _ct_bs(g1h->g1_barrier_set()), 4567 _g1_rem(g1h->g1_rem_set()), 4568 _hash_seed(17), _queue_num(queue_num), 4569 _term_attempts(0), 4570 _surviving_alloc_buffer(g1h->desired_plab_sz(GCAllocForSurvived)), 4571 _tenured_alloc_buffer(g1h->desired_plab_sz(GCAllocForTenured)), 4572 _age_table(false), _scanner(g1h, this, rp), 4573 _strong_roots_time(0), _term_time(0), 4574 _alloc_buffer_waste(0), _undo_waste(0) { 4575 // we allocate G1YoungSurvRateNumRegions plus one entries, since 4576 // we "sacrifice" entry 0 to keep track of surviving bytes for 4577 // non-young regions (where the age is -1) 4578 // We also add a few elements at the beginning and at the end in 4579 // an attempt to eliminate cache contention 4580 uint real_length = 1 + _g1h->g1_policy()->young_cset_region_length(); 4581 uint array_length = PADDING_ELEM_NUM + 4582 real_length + 4583 PADDING_ELEM_NUM; 4584 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length, mtGC); 4585 if (_surviving_young_words_base == NULL) 4586 vm_exit_out_of_memory(array_length * sizeof(size_t), OOM_MALLOC_ERROR, 4587 "Not enough space for young surv histo."); 4588 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM; 4589 memset(_surviving_young_words, 0, (size_t) real_length * sizeof(size_t)); 4590 4591 _alloc_buffers[GCAllocForSurvived] = &_surviving_alloc_buffer; 4592 _alloc_buffers[GCAllocForTenured] = &_tenured_alloc_buffer; 4593 4594 _start = os::elapsedTime(); 4595 } 4596 4597 void 4598 G1ParScanThreadState::print_termination_stats_hdr(outputStream* const st) 4599 { 4600 st->print_raw_cr("GC Termination Stats"); 4601 st->print_raw_cr(" elapsed --strong roots-- -------termination-------" 4602 " ------waste (KiB)------"); 4603 st->print_raw_cr("thr ms ms % ms % attempts" 4604 " total alloc undo"); 4605 st->print_raw_cr("--- --------- --------- ------ --------- ------ --------" 4606 " ------- ------- -------"); 4607 } 4608 4609 void 4610 G1ParScanThreadState::print_termination_stats(int i, 4611 outputStream* const st) const 4612 { 4613 const double elapsed_ms = elapsed_time() * 1000.0; 4614 const double s_roots_ms = strong_roots_time() * 1000.0; 4615 const double term_ms = term_time() * 1000.0; 4616 st->print_cr("%3d %9.2f %9.2f %6.2f " 4617 "%9.2f %6.2f " SIZE_FORMAT_W(8) " " 4618 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7), 4619 i, elapsed_ms, s_roots_ms, s_roots_ms * 100 / elapsed_ms, 4620 term_ms, term_ms * 100 / elapsed_ms, term_attempts(), 4621 (alloc_buffer_waste() + undo_waste()) * HeapWordSize / K, 4622 alloc_buffer_waste() * HeapWordSize / K, 4623 undo_waste() * HeapWordSize / K); 4624 } 4625 4626 #ifdef ASSERT 4627 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const { 4628 assert(ref != NULL, "invariant"); 4629 assert(UseCompressedOops, "sanity"); 4630 assert(!has_partial_array_mask(ref), err_msg("ref=" PTR_FORMAT, ref)); 4631 oop p = oopDesc::load_decode_heap_oop(ref); 4632 assert(_g1h->is_in_g1_reserved(p), 4633 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p)); 4634 return true; 4635 } 4636 4637 bool G1ParScanThreadState::verify_ref(oop* ref) const { 4638 assert(ref != NULL, "invariant"); 4639 if (has_partial_array_mask(ref)) { 4640 // Must be in the collection set--it's already been copied. 4641 oop p = clear_partial_array_mask(ref); 4642 assert(_g1h->obj_in_cs(p), 4643 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p)); 4644 } else { 4645 oop p = oopDesc::load_decode_heap_oop(ref); 4646 assert(_g1h->is_in_g1_reserved(p), 4647 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p)); 4648 } 4649 return true; 4650 } 4651 4652 bool G1ParScanThreadState::verify_task(StarTask ref) const { 4653 if (ref.is_narrow()) { 4654 return verify_ref((narrowOop*) ref); 4655 } else { 4656 return verify_ref((oop*) ref); 4657 } 4658 } 4659 #endif // ASSERT 4660 4661 void G1ParScanThreadState::trim_queue() { 4662 assert(_evac_failure_cl != NULL, "not set"); 4663 4664 StarTask ref; 4665 do { 4666 // Drain the overflow stack first, so other threads can steal. 4667 while (refs()->pop_overflow(ref)) { 4668 deal_with_reference(ref); 4669 } 4670 4671 while (refs()->pop_local(ref)) { 4672 deal_with_reference(ref); 4673 } 4674 } while (!refs()->is_empty()); 4675 } 4676 4677 G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1, 4678 G1ParScanThreadState* par_scan_state) : 4679 _g1(g1), _par_scan_state(par_scan_state), 4680 _worker_id(par_scan_state->queue_num()) { } 4681 4682 void G1ParCopyHelper::mark_object(oop obj) { 4683 assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet"); 4684 4685 // We know that the object is not moving so it's safe to read its size. 4686 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id); 4687 } 4688 4689 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) { 4690 assert(from_obj->is_forwarded(), "from obj should be forwarded"); 4691 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee"); 4692 assert(from_obj != to_obj, "should not be self-forwarded"); 4693 4694 assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet"); 4695 assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet"); 4696 4697 // The object might be in the process of being copied by another 4698 // worker so we cannot trust that its to-space image is 4699 // well-formed. So we have to read its size from its from-space 4700 // image which we know should not be changing. 4701 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id); 4702 } 4703 4704 oop G1ParScanThreadState::copy_to_survivor_space(oop const old) { 4705 size_t word_sz = old->size(); 4706 HeapRegion* from_region = _g1h->heap_region_containing_raw(old); 4707 // +1 to make the -1 indexes valid... 4708 int young_index = from_region->young_index_in_cset()+1; 4709 assert( (from_region->is_young() && young_index > 0) || 4710 (!from_region->is_young() && young_index == 0), "invariant" ); 4711 G1CollectorPolicy* g1p = _g1h->g1_policy(); 4712 markOop m = old->mark(); 4713 int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age() 4714 : m->age(); 4715 GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age, 4716 word_sz); 4717 HeapWord* obj_ptr = allocate(alloc_purpose, word_sz); 4718 #ifndef PRODUCT 4719 // Should this evacuation fail? 4720 if (_g1h->evacuation_should_fail()) { 4721 if (obj_ptr != NULL) { 4722 undo_allocation(alloc_purpose, obj_ptr, word_sz); 4723 obj_ptr = NULL; 4724 } 4725 } 4726 #endif // !PRODUCT 4727 4728 if (obj_ptr == NULL) { 4729 // This will either forward-to-self, or detect that someone else has 4730 // installed a forwarding pointer. 4731 return _g1h->handle_evacuation_failure_par(this, old); 4732 } 4733 4734 oop obj = oop(obj_ptr); 4735 4736 // We're going to allocate linearly, so might as well prefetch ahead. 4737 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes); 4738 4739 oop forward_ptr = old->forward_to_atomic(obj); 4740 if (forward_ptr == NULL) { 4741 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz); 4742 4743 // alloc_purpose is just a hint to allocate() above, recheck the type of region 4744 // we actually allocated from and update alloc_purpose accordingly 4745 HeapRegion* to_region = _g1h->heap_region_containing_raw(obj_ptr); 4746 alloc_purpose = to_region->is_young() ? GCAllocForSurvived : GCAllocForTenured; 4747 4748 if (g1p->track_object_age(alloc_purpose)) { 4749 // We could simply do obj->incr_age(). However, this causes a 4750 // performance issue. obj->incr_age() will first check whether 4751 // the object has a displaced mark by checking its mark word; 4752 // getting the mark word from the new location of the object 4753 // stalls. So, given that we already have the mark word and we 4754 // are about to install it anyway, it's better to increase the 4755 // age on the mark word, when the object does not have a 4756 // displaced mark word. We're not expecting many objects to have 4757 // a displaced marked word, so that case is not optimized 4758 // further (it could be...) and we simply call obj->incr_age(). 4759 4760 if (m->has_displaced_mark_helper()) { 4761 // in this case, we have to install the mark word first, 4762 // otherwise obj looks to be forwarded (the old mark word, 4763 // which contains the forward pointer, was copied) 4764 obj->set_mark(m); 4765 obj->incr_age(); 4766 } else { 4767 m = m->incr_age(); 4768 obj->set_mark(m); 4769 } 4770 age_table()->add(obj, word_sz); 4771 } else { 4772 obj->set_mark(m); 4773 } 4774 4775 if (G1StringDedup::is_enabled()) { 4776 G1StringDedup::enqueue_from_evacuation(from_region->is_young(), 4777 to_region->is_young(), 4778 queue_num(), 4779 obj); 4780 } 4781 4782 size_t* surv_young_words = surviving_young_words(); 4783 surv_young_words[young_index] += word_sz; 4784 4785 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) { 4786 // We keep track of the next start index in the length field of 4787 // the to-space object. The actual length can be found in the 4788 // length field of the from-space object. 4789 arrayOop(obj)->set_length(0); 4790 oop* old_p = set_partial_array_mask(old); 4791 push_on_queue(old_p); 4792 } else { 4793 // No point in using the slower heap_region_containing() method, 4794 // given that we know obj is in the heap. 4795 _scanner.set_region(_g1h->heap_region_containing_raw(obj)); 4796 obj->oop_iterate_backwards(&_scanner); 4797 } 4798 } else { 4799 undo_allocation(alloc_purpose, obj_ptr, word_sz); 4800 obj = forward_ptr; 4801 } 4802 return obj; 4803 } 4804 4805 template <class T> 4806 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) { 4807 if (_g1->heap_region_containing_raw(new_obj)->is_young()) { 4808 _scanned_klass->record_modified_oops(); 4809 } 4810 } 4811 4812 template <G1Barrier barrier, bool do_mark_object> 4813 template <class T> 4814 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) { 4815 T heap_oop = oopDesc::load_heap_oop(p); 4816 4817 if (oopDesc::is_null(heap_oop)) { 4818 return; 4819 } 4820 4821 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 4822 4823 assert(_worker_id == _par_scan_state->queue_num(), "sanity"); 4824 4825 if (_g1->in_cset_fast_test(obj)) { 4826 oop forwardee; 4827 if (obj->is_forwarded()) { 4828 forwardee = obj->forwardee(); 4829 } else { 4830 forwardee = _par_scan_state->copy_to_survivor_space(obj); 4831 } 4832 assert(forwardee != NULL, "forwardee should not be NULL"); 4833 oopDesc::encode_store_heap_oop(p, forwardee); 4834 if (do_mark_object && forwardee != obj) { 4835 // If the object is self-forwarded we don't need to explicitly 4836 // mark it, the evacuation failure protocol will do so. 4837 mark_forwarded_object(obj, forwardee); 4838 } 4839 4840 if (barrier == G1BarrierKlass) { 4841 do_klass_barrier(p, forwardee); 4842 } 4843 } else { 4844 // The object is not in collection set. If we're a root scanning 4845 // closure during an initial mark pause (i.e. do_mark_object will 4846 // be true) then attempt to mark the object. 4847 if (do_mark_object) { 4848 mark_object(obj); 4849 } 4850 } 4851 4852 if (barrier == G1BarrierEvac) { 4853 _par_scan_state->update_rs(_from, p, _worker_id); 4854 } 4855 } 4856 4857 template void G1ParCopyClosure<G1BarrierEvac, false>::do_oop_work(oop* p); 4858 template void G1ParCopyClosure<G1BarrierEvac, false>::do_oop_work(narrowOop* p); 4859 4860 class G1ParEvacuateFollowersClosure : public VoidClosure { 4861 protected: 4862 G1CollectedHeap* _g1h; 4863 G1ParScanThreadState* _par_scan_state; 4864 RefToScanQueueSet* _queues; 4865 ParallelTaskTerminator* _terminator; 4866 4867 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 4868 RefToScanQueueSet* queues() { return _queues; } 4869 ParallelTaskTerminator* terminator() { return _terminator; } 4870 4871 public: 4872 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h, 4873 G1ParScanThreadState* par_scan_state, 4874 RefToScanQueueSet* queues, 4875 ParallelTaskTerminator* terminator) 4876 : _g1h(g1h), _par_scan_state(par_scan_state), 4877 _queues(queues), _terminator(terminator) {} 4878 4879 void do_void(); 4880 4881 private: 4882 inline bool offer_termination(); 4883 }; 4884 4885 bool G1ParEvacuateFollowersClosure::offer_termination() { 4886 G1ParScanThreadState* const pss = par_scan_state(); 4887 pss->start_term_time(); 4888 const bool res = terminator()->offer_termination(); 4889 pss->end_term_time(); 4890 return res; 4891 } 4892 4893 void G1ParEvacuateFollowersClosure::do_void() { 4894 StarTask stolen_task; 4895 G1ParScanThreadState* const pss = par_scan_state(); 4896 pss->trim_queue(); 4897 4898 do { 4899 while (queues()->steal(pss->queue_num(), pss->hash_seed(), stolen_task)) { 4900 assert(pss->verify_task(stolen_task), "sanity"); 4901 if (stolen_task.is_narrow()) { 4902 pss->deal_with_reference((narrowOop*) stolen_task); 4903 } else { 4904 pss->deal_with_reference((oop*) stolen_task); 4905 } 4906 4907 // We've just processed a reference and we might have made 4908 // available new entries on the queues. So we have to make sure 4909 // we drain the queues as necessary. 4910 pss->trim_queue(); 4911 } 4912 } while (!offer_termination()); 4913 } 4914 4915 class G1KlassScanClosure : public KlassClosure { 4916 G1ParCopyHelper* _closure; 4917 bool _process_only_dirty; 4918 int _count; 4919 public: 4920 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty) 4921 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {} 4922 void do_klass(Klass* klass) { 4923 // If the klass has not been dirtied we know that there's 4924 // no references into the young gen and we can skip it. 4925 if (!_process_only_dirty || klass->has_modified_oops()) { 4926 // Clean the klass since we're going to scavenge all the metadata. 4927 klass->clear_modified_oops(); 4928 4929 // Tell the closure that this klass is the Klass to scavenge 4930 // and is the one to dirty if oops are left pointing into the young gen. 4931 _closure->set_scanned_klass(klass); 4932 4933 klass->oops_do(_closure); 4934 4935 _closure->set_scanned_klass(NULL); 4936 } 4937 _count++; 4938 } 4939 }; 4940 4941 class G1ParTask : public AbstractGangTask { 4942 protected: 4943 G1CollectedHeap* _g1h; 4944 RefToScanQueueSet *_queues; 4945 ParallelTaskTerminator _terminator; 4946 uint _n_workers; 4947 4948 Mutex _stats_lock; 4949 Mutex* stats_lock() { return &_stats_lock; } 4950 4951 size_t getNCards() { 4952 return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1) 4953 / G1BlockOffsetSharedArray::N_bytes; 4954 } 4955 4956 public: 4957 G1ParTask(G1CollectedHeap* g1h, 4958 RefToScanQueueSet *task_queues) 4959 : AbstractGangTask("G1 collection"), 4960 _g1h(g1h), 4961 _queues(task_queues), 4962 _terminator(0, _queues), 4963 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true) 4964 {} 4965 4966 RefToScanQueueSet* queues() { return _queues; } 4967 4968 RefToScanQueue *work_queue(int i) { 4969 return queues()->queue(i); 4970 } 4971 4972 ParallelTaskTerminator* terminator() { return &_terminator; } 4973 4974 virtual void set_for_termination(int active_workers) { 4975 // This task calls set_n_termination() in par_non_clean_card_iterate_work() 4976 // in the young space (_par_seq_tasks) in the G1 heap 4977 // for SequentialSubTasksDone. 4978 // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap 4979 // both of which need setting by set_n_termination(). 4980 _g1h->SharedHeap::set_n_termination(active_workers); 4981 _g1h->set_n_termination(active_workers); 4982 terminator()->reset_for_reuse(active_workers); 4983 _n_workers = active_workers; 4984 } 4985 4986 void work(uint worker_id) { 4987 if (worker_id >= _n_workers) return; // no work needed this round 4988 4989 double start_time_ms = os::elapsedTime() * 1000.0; 4990 _g1h->g1_policy()->phase_times()->record_gc_worker_start_time(worker_id, start_time_ms); 4991 4992 { 4993 ResourceMark rm; 4994 HandleMark hm; 4995 4996 ReferenceProcessor* rp = _g1h->ref_processor_stw(); 4997 4998 G1ParScanThreadState pss(_g1h, worker_id, rp); 4999 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp); 5000 5001 pss.set_evac_failure_closure(&evac_failure_cl); 5002 5003 G1ParScanExtRootClosure only_scan_root_cl(_g1h, &pss, rp); 5004 G1ParScanMetadataClosure only_scan_metadata_cl(_g1h, &pss, rp); 5005 5006 G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss, rp); 5007 G1ParScanAndMarkMetadataClosure scan_mark_metadata_cl(_g1h, &pss, rp); 5008 5009 bool only_young = _g1h->g1_policy()->gcs_are_young(); 5010 G1KlassScanClosure scan_mark_klasses_cl_s(&scan_mark_metadata_cl, false); 5011 G1KlassScanClosure only_scan_klasses_cl_s(&only_scan_metadata_cl, only_young); 5012 5013 OopClosure* scan_root_cl = &only_scan_root_cl; 5014 G1KlassScanClosure* scan_klasses_cl = &only_scan_klasses_cl_s; 5015 5016 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5017 // We also need to mark copied objects. 5018 scan_root_cl = &scan_mark_root_cl; 5019 scan_klasses_cl = &scan_mark_klasses_cl_s; 5020 } 5021 5022 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss); 5023 5024 // Don't scan the scavengable methods in the code cache as part 5025 // of strong root scanning. The code roots that point into a 5026 // region in the collection set are scanned when we scan the 5027 // region's RSet. 5028 int so = SharedHeap::SO_AllClasses | SharedHeap::SO_Strings; 5029 5030 pss.start_strong_roots(); 5031 _g1h->g1_process_strong_roots(/* is scavenging */ true, 5032 SharedHeap::ScanningOption(so), 5033 scan_root_cl, 5034 &push_heap_rs_cl, 5035 scan_klasses_cl, 5036 worker_id); 5037 pss.end_strong_roots(); 5038 5039 { 5040 double start = os::elapsedTime(); 5041 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator); 5042 evac.do_void(); 5043 double elapsed_ms = (os::elapsedTime()-start)*1000.0; 5044 double term_ms = pss.term_time()*1000.0; 5045 _g1h->g1_policy()->phase_times()->add_obj_copy_time(worker_id, elapsed_ms-term_ms); 5046 _g1h->g1_policy()->phase_times()->record_termination(worker_id, term_ms, pss.term_attempts()); 5047 } 5048 _g1h->g1_policy()->record_thread_age_table(pss.age_table()); 5049 _g1h->update_surviving_young_words(pss.surviving_young_words()+1); 5050 5051 if (ParallelGCVerbose) { 5052 MutexLocker x(stats_lock()); 5053 pss.print_termination_stats(worker_id); 5054 } 5055 5056 assert(pss.refs()->is_empty(), "should be empty"); 5057 5058 // Close the inner scope so that the ResourceMark and HandleMark 5059 // destructors are executed here and are included as part of the 5060 // "GC Worker Time". 5061 } 5062 5063 double end_time_ms = os::elapsedTime() * 1000.0; 5064 _g1h->g1_policy()->phase_times()->record_gc_worker_end_time(worker_id, end_time_ms); 5065 } 5066 }; 5067 5068 // *** Common G1 Evacuation Stuff 5069 5070 // This method is run in a GC worker. 5071 5072 void 5073 G1CollectedHeap:: 5074 g1_process_strong_roots(bool is_scavenging, 5075 ScanningOption so, 5076 OopClosure* scan_non_heap_roots, 5077 OopsInHeapRegionClosure* scan_rs, 5078 G1KlassScanClosure* scan_klasses, 5079 uint worker_i) { 5080 5081 // First scan the strong roots 5082 double ext_roots_start = os::elapsedTime(); 5083 double closure_app_time_sec = 0.0; 5084 5085 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots); 5086 5087 process_strong_roots(false, // no scoping; this is parallel code 5088 so, 5089 &buf_scan_non_heap_roots, 5090 scan_klasses 5091 ); 5092 5093 // Now the CM ref_processor roots. 5094 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) { 5095 // We need to treat the discovered reference lists of the 5096 // concurrent mark ref processor as roots and keep entries 5097 // (which are added by the marking threads) on them live 5098 // until they can be processed at the end of marking. 5099 ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots); 5100 } 5101 5102 // Finish up any enqueued closure apps (attributed as object copy time). 5103 buf_scan_non_heap_roots.done(); 5104 5105 double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds(); 5106 5107 g1_policy()->phase_times()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0); 5108 5109 double ext_root_time_ms = 5110 ((os::elapsedTime() - ext_roots_start) - obj_copy_time_sec) * 1000.0; 5111 5112 g1_policy()->phase_times()->record_ext_root_scan_time(worker_i, ext_root_time_ms); 5113 5114 // During conc marking we have to filter the per-thread SATB buffers 5115 // to make sure we remove any oops into the CSet (which will show up 5116 // as implicitly live). 5117 double satb_filtering_ms = 0.0; 5118 if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers)) { 5119 if (mark_in_progress()) { 5120 double satb_filter_start = os::elapsedTime(); 5121 5122 JavaThread::satb_mark_queue_set().filter_thread_buffers(); 5123 5124 satb_filtering_ms = (os::elapsedTime() - satb_filter_start) * 1000.0; 5125 } 5126 } 5127 g1_policy()->phase_times()->record_satb_filtering_time(worker_i, satb_filtering_ms); 5128 5129 // If this is an initial mark pause, and we're not scanning 5130 // the entire code cache, we need to mark the oops in the 5131 // strong code root lists for the regions that are not in 5132 // the collection set. 5133 // Note all threads participate in this set of root tasks. 5134 double mark_strong_code_roots_ms = 0.0; 5135 if (g1_policy()->during_initial_mark_pause() && !(so & SO_AllCodeCache)) { 5136 double mark_strong_roots_start = os::elapsedTime(); 5137 mark_strong_code_roots(worker_i); 5138 mark_strong_code_roots_ms = (os::elapsedTime() - mark_strong_roots_start) * 1000.0; 5139 } 5140 g1_policy()->phase_times()->record_strong_code_root_mark_time(worker_i, mark_strong_code_roots_ms); 5141 5142 // Now scan the complement of the collection set. 5143 CodeBlobToOopClosure eager_scan_code_roots(scan_non_heap_roots, true /* do_marking */); 5144 g1_rem_set()->oops_into_collection_set_do(scan_rs, &eager_scan_code_roots, worker_i); 5145 5146 _process_strong_tasks->all_tasks_completed(); 5147 } 5148 5149 class G1StringSymbolTableUnlinkTask : public AbstractGangTask { 5150 private: 5151 BoolObjectClosure* _is_alive; 5152 int _initial_string_table_size; 5153 int _initial_symbol_table_size; 5154 5155 bool _process_strings; 5156 int _strings_processed; 5157 int _strings_removed; 5158 5159 bool _process_symbols; 5160 int _symbols_processed; 5161 int _symbols_removed; 5162 5163 bool _do_in_parallel; 5164 public: 5165 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) : 5166 AbstractGangTask("Par String/Symbol table unlink"), _is_alive(is_alive), 5167 _do_in_parallel(G1CollectedHeap::use_parallel_gc_threads()), 5168 _process_strings(process_strings), _strings_processed(0), _strings_removed(0), 5169 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) { 5170 5171 _initial_string_table_size = StringTable::the_table()->table_size(); 5172 _initial_symbol_table_size = SymbolTable::the_table()->table_size(); 5173 if (process_strings) { 5174 StringTable::clear_parallel_claimed_index(); 5175 } 5176 if (process_symbols) { 5177 SymbolTable::clear_parallel_claimed_index(); 5178 } 5179 } 5180 5181 ~G1StringSymbolTableUnlinkTask() { 5182 guarantee(!_process_strings || !_do_in_parallel || StringTable::parallel_claimed_index() >= _initial_string_table_size, 5183 err_msg("claim value %d after unlink less than initial string table size %d", 5184 StringTable::parallel_claimed_index(), _initial_string_table_size)); 5185 guarantee(!_process_symbols || !_do_in_parallel || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size, 5186 err_msg("claim value %d after unlink less than initial symbol table size %d", 5187 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size)); 5188 } 5189 5190 void work(uint worker_id) { 5191 if (_do_in_parallel) { 5192 int strings_processed = 0; 5193 int strings_removed = 0; 5194 int symbols_processed = 0; 5195 int symbols_removed = 0; 5196 if (_process_strings) { 5197 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed); 5198 Atomic::add(strings_processed, &_strings_processed); 5199 Atomic::add(strings_removed, &_strings_removed); 5200 } 5201 if (_process_symbols) { 5202 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed); 5203 Atomic::add(symbols_processed, &_symbols_processed); 5204 Atomic::add(symbols_removed, &_symbols_removed); 5205 } 5206 } else { 5207 if (_process_strings) { 5208 StringTable::unlink(_is_alive, &_strings_processed, &_strings_removed); 5209 } 5210 if (_process_symbols) { 5211 SymbolTable::unlink(&_symbols_processed, &_symbols_removed); 5212 } 5213 } 5214 } 5215 5216 size_t strings_processed() const { return (size_t)_strings_processed; } 5217 size_t strings_removed() const { return (size_t)_strings_removed; } 5218 5219 size_t symbols_processed() const { return (size_t)_symbols_processed; } 5220 size_t symbols_removed() const { return (size_t)_symbols_removed; } 5221 }; 5222 5223 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive, 5224 bool process_strings, bool process_symbols) { 5225 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ? 5226 _g1h->workers()->active_workers() : 1); 5227 5228 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols); 5229 if (G1CollectedHeap::use_parallel_gc_threads()) { 5230 set_par_threads(n_workers); 5231 workers()->run_task(&g1_unlink_task); 5232 set_par_threads(0); 5233 } else { 5234 g1_unlink_task.work(0); 5235 } 5236 if (G1TraceStringSymbolTableScrubbing) { 5237 gclog_or_tty->print_cr("Cleaned string and symbol table, " 5238 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, " 5239 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed", 5240 g1_unlink_task.strings_processed(), g1_unlink_task.strings_removed(), 5241 g1_unlink_task.symbols_processed(), g1_unlink_task.symbols_removed()); 5242 } 5243 5244 if (G1StringDedup::is_enabled()) { 5245 G1StringDedup::unlink(is_alive); 5246 } 5247 } 5248 5249 class G1RedirtyLoggedCardsTask : public AbstractGangTask { 5250 private: 5251 DirtyCardQueueSet* _queue; 5252 public: 5253 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { } 5254 5255 virtual void work(uint worker_id) { 5256 double start_time = os::elapsedTime(); 5257 5258 RedirtyLoggedCardTableEntryClosure cl; 5259 if (G1CollectedHeap::heap()->use_parallel_gc_threads()) { 5260 _queue->par_apply_closure_to_all_completed_buffers(&cl); 5261 } else { 5262 _queue->apply_closure_to_all_completed_buffers(&cl); 5263 } 5264 5265 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times(); 5266 timer->record_redirty_logged_cards_time_ms(worker_id, (os::elapsedTime() - start_time) * 1000.0); 5267 timer->record_redirty_logged_cards_processed_cards(worker_id, cl.num_processed()); 5268 } 5269 }; 5270 5271 void G1CollectedHeap::redirty_logged_cards() { 5272 guarantee(G1DeferredRSUpdate, "Must only be called when using deferred RS updates."); 5273 double redirty_logged_cards_start = os::elapsedTime(); 5274 5275 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ? 5276 _g1h->workers()->active_workers() : 1); 5277 5278 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set()); 5279 dirty_card_queue_set().reset_for_par_iteration(); 5280 if (use_parallel_gc_threads()) { 5281 set_par_threads(n_workers); 5282 workers()->run_task(&redirty_task); 5283 set_par_threads(0); 5284 } else { 5285 redirty_task.work(0); 5286 } 5287 5288 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set(); 5289 dcq.merge_bufferlists(&dirty_card_queue_set()); 5290 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed"); 5291 5292 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0); 5293 } 5294 5295 // Weak Reference Processing support 5296 5297 // An always "is_alive" closure that is used to preserve referents. 5298 // If the object is non-null then it's alive. Used in the preservation 5299 // of referent objects that are pointed to by reference objects 5300 // discovered by the CM ref processor. 5301 class G1AlwaysAliveClosure: public BoolObjectClosure { 5302 G1CollectedHeap* _g1; 5303 public: 5304 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 5305 bool do_object_b(oop p) { 5306 if (p != NULL) { 5307 return true; 5308 } 5309 return false; 5310 } 5311 }; 5312 5313 bool G1STWIsAliveClosure::do_object_b(oop p) { 5314 // An object is reachable if it is outside the collection set, 5315 // or is inside and copied. 5316 return !_g1->obj_in_cs(p) || p->is_forwarded(); 5317 } 5318 5319 // Non Copying Keep Alive closure 5320 class G1KeepAliveClosure: public OopClosure { 5321 G1CollectedHeap* _g1; 5322 public: 5323 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 5324 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } 5325 void do_oop( oop* p) { 5326 oop obj = *p; 5327 5328 if (_g1->obj_in_cs(obj)) { 5329 assert( obj->is_forwarded(), "invariant" ); 5330 *p = obj->forwardee(); 5331 } 5332 } 5333 }; 5334 5335 // Copying Keep Alive closure - can be called from both 5336 // serial and parallel code as long as different worker 5337 // threads utilize different G1ParScanThreadState instances 5338 // and different queues. 5339 5340 class G1CopyingKeepAliveClosure: public OopClosure { 5341 G1CollectedHeap* _g1h; 5342 OopClosure* _copy_non_heap_obj_cl; 5343 G1ParScanThreadState* _par_scan_state; 5344 5345 public: 5346 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, 5347 OopClosure* non_heap_obj_cl, 5348 G1ParScanThreadState* pss): 5349 _g1h(g1h), 5350 _copy_non_heap_obj_cl(non_heap_obj_cl), 5351 _par_scan_state(pss) 5352 {} 5353 5354 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 5355 virtual void do_oop( oop* p) { do_oop_work(p); } 5356 5357 template <class T> void do_oop_work(T* p) { 5358 oop obj = oopDesc::load_decode_heap_oop(p); 5359 5360 if (_g1h->obj_in_cs(obj)) { 5361 // If the referent object has been forwarded (either copied 5362 // to a new location or to itself in the event of an 5363 // evacuation failure) then we need to update the reference 5364 // field and, if both reference and referent are in the G1 5365 // heap, update the RSet for the referent. 5366 // 5367 // If the referent has not been forwarded then we have to keep 5368 // it alive by policy. Therefore we have copy the referent. 5369 // 5370 // If the reference field is in the G1 heap then we can push 5371 // on the PSS queue. When the queue is drained (after each 5372 // phase of reference processing) the object and it's followers 5373 // will be copied, the reference field set to point to the 5374 // new location, and the RSet updated. Otherwise we need to 5375 // use the the non-heap or metadata closures directly to copy 5376 // the referent object and update the pointer, while avoiding 5377 // updating the RSet. 5378 5379 if (_g1h->is_in_g1_reserved(p)) { 5380 _par_scan_state->push_on_queue(p); 5381 } else { 5382 assert(!Metaspace::contains((const void*)p), 5383 err_msg("Unexpectedly found a pointer from metadata: " 5384 PTR_FORMAT, p)); 5385 _copy_non_heap_obj_cl->do_oop(p); 5386 } 5387 } 5388 } 5389 }; 5390 5391 // Serial drain queue closure. Called as the 'complete_gc' 5392 // closure for each discovered list in some of the 5393 // reference processing phases. 5394 5395 class G1STWDrainQueueClosure: public VoidClosure { 5396 protected: 5397 G1CollectedHeap* _g1h; 5398 G1ParScanThreadState* _par_scan_state; 5399 5400 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 5401 5402 public: 5403 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : 5404 _g1h(g1h), 5405 _par_scan_state(pss) 5406 { } 5407 5408 void do_void() { 5409 G1ParScanThreadState* const pss = par_scan_state(); 5410 pss->trim_queue(); 5411 } 5412 }; 5413 5414 // Parallel Reference Processing closures 5415 5416 // Implementation of AbstractRefProcTaskExecutor for parallel reference 5417 // processing during G1 evacuation pauses. 5418 5419 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 5420 private: 5421 G1CollectedHeap* _g1h; 5422 RefToScanQueueSet* _queues; 5423 FlexibleWorkGang* _workers; 5424 int _active_workers; 5425 5426 public: 5427 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, 5428 FlexibleWorkGang* workers, 5429 RefToScanQueueSet *task_queues, 5430 int n_workers) : 5431 _g1h(g1h), 5432 _queues(task_queues), 5433 _workers(workers), 5434 _active_workers(n_workers) 5435 { 5436 assert(n_workers > 0, "shouldn't call this otherwise"); 5437 } 5438 5439 // Executes the given task using concurrent marking worker threads. 5440 virtual void execute(ProcessTask& task); 5441 virtual void execute(EnqueueTask& task); 5442 }; 5443 5444 // Gang task for possibly parallel reference processing 5445 5446 class G1STWRefProcTaskProxy: public AbstractGangTask { 5447 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 5448 ProcessTask& _proc_task; 5449 G1CollectedHeap* _g1h; 5450 RefToScanQueueSet *_task_queues; 5451 ParallelTaskTerminator* _terminator; 5452 5453 public: 5454 G1STWRefProcTaskProxy(ProcessTask& proc_task, 5455 G1CollectedHeap* g1h, 5456 RefToScanQueueSet *task_queues, 5457 ParallelTaskTerminator* terminator) : 5458 AbstractGangTask("Process reference objects in parallel"), 5459 _proc_task(proc_task), 5460 _g1h(g1h), 5461 _task_queues(task_queues), 5462 _terminator(terminator) 5463 {} 5464 5465 virtual void work(uint worker_id) { 5466 // The reference processing task executed by a single worker. 5467 ResourceMark rm; 5468 HandleMark hm; 5469 5470 G1STWIsAliveClosure is_alive(_g1h); 5471 5472 G1ParScanThreadState pss(_g1h, worker_id, NULL); 5473 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL); 5474 5475 pss.set_evac_failure_closure(&evac_failure_cl); 5476 5477 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL); 5478 5479 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL); 5480 5481 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5482 5483 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5484 // We also need to mark copied objects. 5485 copy_non_heap_cl = ©_mark_non_heap_cl; 5486 } 5487 5488 // Keep alive closure. 5489 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss); 5490 5491 // Complete GC closure 5492 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator); 5493 5494 // Call the reference processing task's work routine. 5495 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); 5496 5497 // Note we cannot assert that the refs array is empty here as not all 5498 // of the processing tasks (specifically phase2 - pp2_work) execute 5499 // the complete_gc closure (which ordinarily would drain the queue) so 5500 // the queue may not be empty. 5501 } 5502 }; 5503 5504 // Driver routine for parallel reference processing. 5505 // Creates an instance of the ref processing gang 5506 // task and has the worker threads execute it. 5507 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) { 5508 assert(_workers != NULL, "Need parallel worker threads."); 5509 5510 ParallelTaskTerminator terminator(_active_workers, _queues); 5511 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator); 5512 5513 _g1h->set_par_threads(_active_workers); 5514 _workers->run_task(&proc_task_proxy); 5515 _g1h->set_par_threads(0); 5516 } 5517 5518 // Gang task for parallel reference enqueueing. 5519 5520 class G1STWRefEnqueueTaskProxy: public AbstractGangTask { 5521 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; 5522 EnqueueTask& _enq_task; 5523 5524 public: 5525 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) : 5526 AbstractGangTask("Enqueue reference objects in parallel"), 5527 _enq_task(enq_task) 5528 { } 5529 5530 virtual void work(uint worker_id) { 5531 _enq_task.work(worker_id); 5532 } 5533 }; 5534 5535 // Driver routine for parallel reference enqueueing. 5536 // Creates an instance of the ref enqueueing gang 5537 // task and has the worker threads execute it. 5538 5539 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) { 5540 assert(_workers != NULL, "Need parallel worker threads."); 5541 5542 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task); 5543 5544 _g1h->set_par_threads(_active_workers); 5545 _workers->run_task(&enq_task_proxy); 5546 _g1h->set_par_threads(0); 5547 } 5548 5549 // End of weak reference support closures 5550 5551 // Abstract task used to preserve (i.e. copy) any referent objects 5552 // that are in the collection set and are pointed to by reference 5553 // objects discovered by the CM ref processor. 5554 5555 class G1ParPreserveCMReferentsTask: public AbstractGangTask { 5556 protected: 5557 G1CollectedHeap* _g1h; 5558 RefToScanQueueSet *_queues; 5559 ParallelTaskTerminator _terminator; 5560 uint _n_workers; 5561 5562 public: 5563 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) : 5564 AbstractGangTask("ParPreserveCMReferents"), 5565 _g1h(g1h), 5566 _queues(task_queues), 5567 _terminator(workers, _queues), 5568 _n_workers(workers) 5569 { } 5570 5571 void work(uint worker_id) { 5572 ResourceMark rm; 5573 HandleMark hm; 5574 5575 G1ParScanThreadState pss(_g1h, worker_id, NULL); 5576 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL); 5577 5578 pss.set_evac_failure_closure(&evac_failure_cl); 5579 5580 assert(pss.refs()->is_empty(), "both queue and overflow should be empty"); 5581 5582 5583 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL); 5584 5585 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL); 5586 5587 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5588 5589 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5590 // We also need to mark copied objects. 5591 copy_non_heap_cl = ©_mark_non_heap_cl; 5592 } 5593 5594 // Is alive closure 5595 G1AlwaysAliveClosure always_alive(_g1h); 5596 5597 // Copying keep alive closure. Applied to referent objects that need 5598 // to be copied. 5599 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss); 5600 5601 ReferenceProcessor* rp = _g1h->ref_processor_cm(); 5602 5603 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q(); 5604 uint stride = MIN2(MAX2(_n_workers, 1U), limit); 5605 5606 // limit is set using max_num_q() - which was set using ParallelGCThreads. 5607 // So this must be true - but assert just in case someone decides to 5608 // change the worker ids. 5609 assert(0 <= worker_id && worker_id < limit, "sanity"); 5610 assert(!rp->discovery_is_atomic(), "check this code"); 5611 5612 // Select discovered lists [i, i+stride, i+2*stride,...,limit) 5613 for (uint idx = worker_id; idx < limit; idx += stride) { 5614 DiscoveredList& ref_list = rp->discovered_refs()[idx]; 5615 5616 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive); 5617 while (iter.has_next()) { 5618 // Since discovery is not atomic for the CM ref processor, we 5619 // can see some null referent objects. 5620 iter.load_ptrs(DEBUG_ONLY(true)); 5621 oop ref = iter.obj(); 5622 5623 // This will filter nulls. 5624 if (iter.is_referent_alive()) { 5625 iter.make_referent_alive(); 5626 } 5627 iter.move_to_next(); 5628 } 5629 } 5630 5631 // Drain the queue - which may cause stealing 5632 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator); 5633 drain_queue.do_void(); 5634 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure 5635 assert(pss.refs()->is_empty(), "should be"); 5636 } 5637 }; 5638 5639 // Weak Reference processing during an evacuation pause (part 1). 5640 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) { 5641 double ref_proc_start = os::elapsedTime(); 5642 5643 ReferenceProcessor* rp = _ref_processor_stw; 5644 assert(rp->discovery_enabled(), "should have been enabled"); 5645 5646 // Any reference objects, in the collection set, that were 'discovered' 5647 // by the CM ref processor should have already been copied (either by 5648 // applying the external root copy closure to the discovered lists, or 5649 // by following an RSet entry). 5650 // 5651 // But some of the referents, that are in the collection set, that these 5652 // reference objects point to may not have been copied: the STW ref 5653 // processor would have seen that the reference object had already 5654 // been 'discovered' and would have skipped discovering the reference, 5655 // but would not have treated the reference object as a regular oop. 5656 // As a result the copy closure would not have been applied to the 5657 // referent object. 5658 // 5659 // We need to explicitly copy these referent objects - the references 5660 // will be processed at the end of remarking. 5661 // 5662 // We also need to do this copying before we process the reference 5663 // objects discovered by the STW ref processor in case one of these 5664 // referents points to another object which is also referenced by an 5665 // object discovered by the STW ref processor. 5666 5667 assert(!G1CollectedHeap::use_parallel_gc_threads() || 5668 no_of_gc_workers == workers()->active_workers(), 5669 "Need to reset active GC workers"); 5670 5671 set_par_threads(no_of_gc_workers); 5672 G1ParPreserveCMReferentsTask keep_cm_referents(this, 5673 no_of_gc_workers, 5674 _task_queues); 5675 5676 if (G1CollectedHeap::use_parallel_gc_threads()) { 5677 workers()->run_task(&keep_cm_referents); 5678 } else { 5679 keep_cm_referents.work(0); 5680 } 5681 5682 set_par_threads(0); 5683 5684 // Closure to test whether a referent is alive. 5685 G1STWIsAliveClosure is_alive(this); 5686 5687 // Even when parallel reference processing is enabled, the processing 5688 // of JNI refs is serial and performed serially by the current thread 5689 // rather than by a worker. The following PSS will be used for processing 5690 // JNI refs. 5691 5692 // Use only a single queue for this PSS. 5693 G1ParScanThreadState pss(this, 0, NULL); 5694 5695 // We do not embed a reference processor in the copying/scanning 5696 // closures while we're actually processing the discovered 5697 // reference objects. 5698 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL); 5699 5700 pss.set_evac_failure_closure(&evac_failure_cl); 5701 5702 assert(pss.refs()->is_empty(), "pre-condition"); 5703 5704 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL); 5705 5706 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL); 5707 5708 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5709 5710 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5711 // We also need to mark copied objects. 5712 copy_non_heap_cl = ©_mark_non_heap_cl; 5713 } 5714 5715 // Keep alive closure. 5716 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, &pss); 5717 5718 // Serial Complete GC closure 5719 G1STWDrainQueueClosure drain_queue(this, &pss); 5720 5721 // Setup the soft refs policy... 5722 rp->setup_policy(false); 5723 5724 ReferenceProcessorStats stats; 5725 if (!rp->processing_is_mt()) { 5726 // Serial reference processing... 5727 stats = rp->process_discovered_references(&is_alive, 5728 &keep_alive, 5729 &drain_queue, 5730 NULL, 5731 _gc_timer_stw, 5732 _gc_tracer_stw->gc_id()); 5733 } else { 5734 // Parallel reference processing 5735 assert(rp->num_q() == no_of_gc_workers, "sanity"); 5736 assert(no_of_gc_workers <= rp->max_num_q(), "sanity"); 5737 5738 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers); 5739 stats = rp->process_discovered_references(&is_alive, 5740 &keep_alive, 5741 &drain_queue, 5742 &par_task_executor, 5743 _gc_timer_stw, 5744 _gc_tracer_stw->gc_id()); 5745 } 5746 5747 _gc_tracer_stw->report_gc_reference_stats(stats); 5748 5749 // We have completed copying any necessary live referent objects. 5750 assert(pss.refs()->is_empty(), "both queue and overflow should be empty"); 5751 5752 double ref_proc_time = os::elapsedTime() - ref_proc_start; 5753 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 5754 } 5755 5756 // Weak Reference processing during an evacuation pause (part 2). 5757 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) { 5758 double ref_enq_start = os::elapsedTime(); 5759 5760 ReferenceProcessor* rp = _ref_processor_stw; 5761 assert(!rp->discovery_enabled(), "should have been disabled as part of processing"); 5762 5763 // Now enqueue any remaining on the discovered lists on to 5764 // the pending list. 5765 if (!rp->processing_is_mt()) { 5766 // Serial reference processing... 5767 rp->enqueue_discovered_references(); 5768 } else { 5769 // Parallel reference enqueueing 5770 5771 assert(no_of_gc_workers == workers()->active_workers(), 5772 "Need to reset active workers"); 5773 assert(rp->num_q() == no_of_gc_workers, "sanity"); 5774 assert(no_of_gc_workers <= rp->max_num_q(), "sanity"); 5775 5776 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers); 5777 rp->enqueue_discovered_references(&par_task_executor); 5778 } 5779 5780 rp->verify_no_references_recorded(); 5781 assert(!rp->discovery_enabled(), "should have been disabled"); 5782 5783 // FIXME 5784 // CM's reference processing also cleans up the string and symbol tables. 5785 // Should we do that here also? We could, but it is a serial operation 5786 // and could significantly increase the pause time. 5787 5788 double ref_enq_time = os::elapsedTime() - ref_enq_start; 5789 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0); 5790 } 5791 5792 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) { 5793 _expand_heap_after_alloc_failure = true; 5794 _evacuation_failed = false; 5795 5796 // Should G1EvacuationFailureALot be in effect for this GC? 5797 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) 5798 5799 g1_rem_set()->prepare_for_oops_into_collection_set_do(); 5800 5801 // Disable the hot card cache. 5802 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 5803 hot_card_cache->reset_hot_cache_claimed_index(); 5804 hot_card_cache->set_use_cache(false); 5805 5806 uint n_workers; 5807 if (G1CollectedHeap::use_parallel_gc_threads()) { 5808 n_workers = 5809 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 5810 workers()->active_workers(), 5811 Threads::number_of_non_daemon_threads()); 5812 assert(UseDynamicNumberOfGCThreads || 5813 n_workers == workers()->total_workers(), 5814 "If not dynamic should be using all the workers"); 5815 workers()->set_active_workers(n_workers); 5816 set_par_threads(n_workers); 5817 } else { 5818 assert(n_par_threads() == 0, 5819 "Should be the original non-parallel value"); 5820 n_workers = 1; 5821 } 5822 5823 G1ParTask g1_par_task(this, _task_queues); 5824 5825 init_for_evac_failure(NULL); 5826 5827 rem_set()->prepare_for_younger_refs_iterate(true); 5828 5829 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty"); 5830 double start_par_time_sec = os::elapsedTime(); 5831 double end_par_time_sec; 5832 5833 { 5834 StrongRootsScope srs(this); 5835 5836 if (G1CollectedHeap::use_parallel_gc_threads()) { 5837 // The individual threads will set their evac-failure closures. 5838 if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr(); 5839 // These tasks use ShareHeap::_process_strong_tasks 5840 assert(UseDynamicNumberOfGCThreads || 5841 workers()->active_workers() == workers()->total_workers(), 5842 "If not dynamic should be using all the workers"); 5843 workers()->run_task(&g1_par_task); 5844 } else { 5845 g1_par_task.set_for_termination(n_workers); 5846 g1_par_task.work(0); 5847 } 5848 end_par_time_sec = os::elapsedTime(); 5849 5850 // Closing the inner scope will execute the destructor 5851 // for the StrongRootsScope object. We record the current 5852 // elapsed time before closing the scope so that time 5853 // taken for the SRS destructor is NOT included in the 5854 // reported parallel time. 5855 } 5856 5857 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0; 5858 g1_policy()->phase_times()->record_par_time(par_time_ms); 5859 5860 double code_root_fixup_time_ms = 5861 (os::elapsedTime() - end_par_time_sec) * 1000.0; 5862 g1_policy()->phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms); 5863 5864 set_par_threads(0); 5865 5866 // Process any discovered reference objects - we have 5867 // to do this _before_ we retire the GC alloc regions 5868 // as we may have to copy some 'reachable' referent 5869 // objects (and their reachable sub-graphs) that were 5870 // not copied during the pause. 5871 process_discovered_references(n_workers); 5872 5873 // Weak root processing. 5874 { 5875 G1STWIsAliveClosure is_alive(this); 5876 G1KeepAliveClosure keep_alive(this); 5877 JNIHandles::weak_oops_do(&is_alive, &keep_alive); 5878 if (G1StringDedup::is_enabled()) { 5879 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive); 5880 } 5881 } 5882 5883 release_gc_alloc_regions(n_workers, evacuation_info); 5884 g1_rem_set()->cleanup_after_oops_into_collection_set_do(); 5885 5886 // Reset and re-enable the hot card cache. 5887 // Note the counts for the cards in the regions in the 5888 // collection set are reset when the collection set is freed. 5889 hot_card_cache->reset_hot_cache(); 5890 hot_card_cache->set_use_cache(true); 5891 5892 // Migrate the strong code roots attached to each region in 5893 // the collection set. Ideally we would like to do this 5894 // after we have finished the scanning/evacuation of the 5895 // strong code roots for a particular heap region. 5896 migrate_strong_code_roots(); 5897 5898 purge_code_root_memory(); 5899 5900 if (g1_policy()->during_initial_mark_pause()) { 5901 // Reset the claim values set during marking the strong code roots 5902 reset_heap_region_claim_values(); 5903 } 5904 5905 finalize_for_evac_failure(); 5906 5907 if (evacuation_failed()) { 5908 remove_self_forwarding_pointers(); 5909 5910 // Reset the G1EvacuationFailureALot counters and flags 5911 // Note: the values are reset only when an actual 5912 // evacuation failure occurs. 5913 NOT_PRODUCT(reset_evacuation_should_fail();) 5914 } 5915 5916 // Enqueue any remaining references remaining on the STW 5917 // reference processor's discovered lists. We need to do 5918 // this after the card table is cleaned (and verified) as 5919 // the act of enqueueing entries on to the pending list 5920 // will log these updates (and dirty their associated 5921 // cards). We need these updates logged to update any 5922 // RSets. 5923 enqueue_discovered_references(n_workers); 5924 5925 if (G1DeferredRSUpdate) { 5926 redirty_logged_cards(); 5927 } 5928 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 5929 } 5930 5931 void G1CollectedHeap::free_region(HeapRegion* hr, 5932 FreeRegionList* free_list, 5933 bool par, 5934 bool locked) { 5935 assert(!hr->isHumongous(), "this is only for non-humongous regions"); 5936 assert(!hr->is_empty(), "the region should not be empty"); 5937 assert(free_list != NULL, "pre-condition"); 5938 5939 if (G1VerifyBitmaps) { 5940 MemRegion mr(hr->bottom(), hr->end()); 5941 concurrent_mark()->clearRangePrevBitmap(mr); 5942 } 5943 5944 // Clear the card counts for this region. 5945 // Note: we only need to do this if the region is not young 5946 // (since we don't refine cards in young regions). 5947 if (!hr->is_young()) { 5948 _cg1r->hot_card_cache()->reset_card_counts(hr); 5949 } 5950 hr->hr_clear(par, true /* clear_space */, locked /* locked */); 5951 free_list->add_ordered(hr); 5952 } 5953 5954 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 5955 FreeRegionList* free_list, 5956 bool par) { 5957 assert(hr->startsHumongous(), "this is only for starts humongous regions"); 5958 assert(free_list != NULL, "pre-condition"); 5959 5960 size_t hr_capacity = hr->capacity(); 5961 // We need to read this before we make the region non-humongous, 5962 // otherwise the information will be gone. 5963 uint last_index = hr->last_hc_index(); 5964 hr->set_notHumongous(); 5965 free_region(hr, free_list, par); 5966 5967 uint i = hr->hrs_index() + 1; 5968 while (i < last_index) { 5969 HeapRegion* curr_hr = region_at(i); 5970 assert(curr_hr->continuesHumongous(), "invariant"); 5971 curr_hr->set_notHumongous(); 5972 free_region(curr_hr, free_list, par); 5973 i += 1; 5974 } 5975 } 5976 5977 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed, 5978 const HeapRegionSetCount& humongous_regions_removed) { 5979 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) { 5980 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 5981 _old_set.bulk_remove(old_regions_removed); 5982 _humongous_set.bulk_remove(humongous_regions_removed); 5983 } 5984 5985 } 5986 5987 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) { 5988 assert(list != NULL, "list can't be null"); 5989 if (!list->is_empty()) { 5990 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag); 5991 _free_list.add_ordered(list); 5992 } 5993 } 5994 5995 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) { 5996 assert(_summary_bytes_used >= bytes, 5997 err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" should be >= bytes: "SIZE_FORMAT, 5998 _summary_bytes_used, bytes)); 5999 _summary_bytes_used -= bytes; 6000 } 6001 6002 class G1ParCleanupCTTask : public AbstractGangTask { 6003 G1SATBCardTableModRefBS* _ct_bs; 6004 G1CollectedHeap* _g1h; 6005 HeapRegion* volatile _su_head; 6006 public: 6007 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs, 6008 G1CollectedHeap* g1h) : 6009 AbstractGangTask("G1 Par Cleanup CT Task"), 6010 _ct_bs(ct_bs), _g1h(g1h) { } 6011 6012 void work(uint worker_id) { 6013 HeapRegion* r; 6014 while (r = _g1h->pop_dirty_cards_region()) { 6015 clear_cards(r); 6016 } 6017 } 6018 6019 void clear_cards(HeapRegion* r) { 6020 // Cards of the survivors should have already been dirtied. 6021 if (!r->is_survivor()) { 6022 _ct_bs->clear(MemRegion(r->bottom(), r->end())); 6023 } 6024 } 6025 }; 6026 6027 #ifndef PRODUCT 6028 class G1VerifyCardTableCleanup: public HeapRegionClosure { 6029 G1CollectedHeap* _g1h; 6030 G1SATBCardTableModRefBS* _ct_bs; 6031 public: 6032 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs) 6033 : _g1h(g1h), _ct_bs(ct_bs) { } 6034 virtual bool doHeapRegion(HeapRegion* r) { 6035 if (r->is_survivor()) { 6036 _g1h->verify_dirty_region(r); 6037 } else { 6038 _g1h->verify_not_dirty_region(r); 6039 } 6040 return false; 6041 } 6042 }; 6043 6044 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) { 6045 // All of the region should be clean. 6046 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 6047 MemRegion mr(hr->bottom(), hr->end()); 6048 ct_bs->verify_not_dirty_region(mr); 6049 } 6050 6051 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) { 6052 // We cannot guarantee that [bottom(),end()] is dirty. Threads 6053 // dirty allocated blocks as they allocate them. The thread that 6054 // retires each region and replaces it with a new one will do a 6055 // maximal allocation to fill in [pre_dummy_top(),end()] but will 6056 // not dirty that area (one less thing to have to do while holding 6057 // a lock). So we can only verify that [bottom(),pre_dummy_top()] 6058 // is dirty. 6059 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 6060 MemRegion mr(hr->bottom(), hr->pre_dummy_top()); 6061 if (hr->is_young()) { 6062 ct_bs->verify_g1_young_region(mr); 6063 } else { 6064 ct_bs->verify_dirty_region(mr); 6065 } 6066 } 6067 6068 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) { 6069 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 6070 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) { 6071 verify_dirty_region(hr); 6072 } 6073 } 6074 6075 void G1CollectedHeap::verify_dirty_young_regions() { 6076 verify_dirty_young_list(_young_list->first_region()); 6077 } 6078 6079 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap, 6080 HeapWord* tams, HeapWord* end) { 6081 guarantee(tams <= end, 6082 err_msg("tams: "PTR_FORMAT" end: "PTR_FORMAT, tams, end)); 6083 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end); 6084 if (result < end) { 6085 gclog_or_tty->cr(); 6086 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: "PTR_FORMAT, 6087 bitmap_name, result); 6088 gclog_or_tty->print_cr("## %s tams: "PTR_FORMAT" end: "PTR_FORMAT, 6089 bitmap_name, tams, end); 6090 return false; 6091 } 6092 return true; 6093 } 6094 6095 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) { 6096 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap(); 6097 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap(); 6098 6099 HeapWord* bottom = hr->bottom(); 6100 HeapWord* ptams = hr->prev_top_at_mark_start(); 6101 HeapWord* ntams = hr->next_top_at_mark_start(); 6102 HeapWord* end = hr->end(); 6103 6104 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end); 6105 6106 bool res_n = true; 6107 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window 6108 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap 6109 // if we happen to be in that state. 6110 if (mark_in_progress() || !_cmThread->in_progress()) { 6111 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end); 6112 } 6113 if (!res_p || !res_n) { 6114 gclog_or_tty->print_cr("#### Bitmap verification failed for "HR_FORMAT, 6115 HR_FORMAT_PARAMS(hr)); 6116 gclog_or_tty->print_cr("#### Caller: %s", caller); 6117 return false; 6118 } 6119 return true; 6120 } 6121 6122 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) { 6123 if (!G1VerifyBitmaps) return; 6124 6125 guarantee(verify_bitmaps(caller, hr), "bitmap verification"); 6126 } 6127 6128 class G1VerifyBitmapClosure : public HeapRegionClosure { 6129 private: 6130 const char* _caller; 6131 G1CollectedHeap* _g1h; 6132 bool _failures; 6133 6134 public: 6135 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) : 6136 _caller(caller), _g1h(g1h), _failures(false) { } 6137 6138 bool failures() { return _failures; } 6139 6140 virtual bool doHeapRegion(HeapRegion* hr) { 6141 if (hr->continuesHumongous()) return false; 6142 6143 bool result = _g1h->verify_bitmaps(_caller, hr); 6144 if (!result) { 6145 _failures = true; 6146 } 6147 return false; 6148 } 6149 }; 6150 6151 void G1CollectedHeap::check_bitmaps(const char* caller) { 6152 if (!G1VerifyBitmaps) return; 6153 6154 G1VerifyBitmapClosure cl(caller, this); 6155 heap_region_iterate(&cl); 6156 guarantee(!cl.failures(), "bitmap verification"); 6157 } 6158 #endif // PRODUCT 6159 6160 void G1CollectedHeap::cleanUpCardTable() { 6161 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 6162 double start = os::elapsedTime(); 6163 6164 { 6165 // Iterate over the dirty cards region list. 6166 G1ParCleanupCTTask cleanup_task(ct_bs, this); 6167 6168 if (G1CollectedHeap::use_parallel_gc_threads()) { 6169 set_par_threads(); 6170 workers()->run_task(&cleanup_task); 6171 set_par_threads(0); 6172 } else { 6173 while (_dirty_cards_region_list) { 6174 HeapRegion* r = _dirty_cards_region_list; 6175 cleanup_task.clear_cards(r); 6176 _dirty_cards_region_list = r->get_next_dirty_cards_region(); 6177 if (_dirty_cards_region_list == r) { 6178 // The last region. 6179 _dirty_cards_region_list = NULL; 6180 } 6181 r->set_next_dirty_cards_region(NULL); 6182 } 6183 } 6184 #ifndef PRODUCT 6185 if (G1VerifyCTCleanup || VerifyAfterGC) { 6186 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs); 6187 heap_region_iterate(&cleanup_verifier); 6188 } 6189 #endif 6190 } 6191 6192 double elapsed = os::elapsedTime() - start; 6193 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0); 6194 } 6195 6196 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) { 6197 size_t pre_used = 0; 6198 FreeRegionList local_free_list("Local List for CSet Freeing"); 6199 6200 double young_time_ms = 0.0; 6201 double non_young_time_ms = 0.0; 6202 6203 // Since the collection set is a superset of the the young list, 6204 // all we need to do to clear the young list is clear its 6205 // head and length, and unlink any young regions in the code below 6206 _young_list->clear(); 6207 6208 G1CollectorPolicy* policy = g1_policy(); 6209 6210 double start_sec = os::elapsedTime(); 6211 bool non_young = true; 6212 6213 HeapRegion* cur = cs_head; 6214 int age_bound = -1; 6215 size_t rs_lengths = 0; 6216 6217 while (cur != NULL) { 6218 assert(!is_on_master_free_list(cur), "sanity"); 6219 if (non_young) { 6220 if (cur->is_young()) { 6221 double end_sec = os::elapsedTime(); 6222 double elapsed_ms = (end_sec - start_sec) * 1000.0; 6223 non_young_time_ms += elapsed_ms; 6224 6225 start_sec = os::elapsedTime(); 6226 non_young = false; 6227 } 6228 } else { 6229 if (!cur->is_young()) { 6230 double end_sec = os::elapsedTime(); 6231 double elapsed_ms = (end_sec - start_sec) * 1000.0; 6232 young_time_ms += elapsed_ms; 6233 6234 start_sec = os::elapsedTime(); 6235 non_young = true; 6236 } 6237 } 6238 6239 rs_lengths += cur->rem_set()->occupied_locked(); 6240 6241 HeapRegion* next = cur->next_in_collection_set(); 6242 assert(cur->in_collection_set(), "bad CS"); 6243 cur->set_next_in_collection_set(NULL); 6244 cur->set_in_collection_set(false); 6245 6246 if (cur->is_young()) { 6247 int index = cur->young_index_in_cset(); 6248 assert(index != -1, "invariant"); 6249 assert((uint) index < policy->young_cset_region_length(), "invariant"); 6250 size_t words_survived = _surviving_young_words[index]; 6251 cur->record_surv_words_in_group(words_survived); 6252 6253 // At this point the we have 'popped' cur from the collection set 6254 // (linked via next_in_collection_set()) but it is still in the 6255 // young list (linked via next_young_region()). Clear the 6256 // _next_young_region field. 6257 cur->set_next_young_region(NULL); 6258 } else { 6259 int index = cur->young_index_in_cset(); 6260 assert(index == -1, "invariant"); 6261 } 6262 6263 assert( (cur->is_young() && cur->young_index_in_cset() > -1) || 6264 (!cur->is_young() && cur->young_index_in_cset() == -1), 6265 "invariant" ); 6266 6267 if (!cur->evacuation_failed()) { 6268 MemRegion used_mr = cur->used_region(); 6269 6270 // And the region is empty. 6271 assert(!used_mr.is_empty(), "Should not have empty regions in a CS."); 6272 pre_used += cur->used(); 6273 free_region(cur, &local_free_list, false /* par */, true /* locked */); 6274 } else { 6275 cur->uninstall_surv_rate_group(); 6276 if (cur->is_young()) { 6277 cur->set_young_index_in_cset(-1); 6278 } 6279 cur->set_not_young(); 6280 cur->set_evacuation_failed(false); 6281 // The region is now considered to be old. 6282 _old_set.add(cur); 6283 evacuation_info.increment_collectionset_used_after(cur->used()); 6284 } 6285 cur = next; 6286 } 6287 6288 evacuation_info.set_regions_freed(local_free_list.length()); 6289 policy->record_max_rs_lengths(rs_lengths); 6290 policy->cset_regions_freed(); 6291 6292 double end_sec = os::elapsedTime(); 6293 double elapsed_ms = (end_sec - start_sec) * 1000.0; 6294 6295 if (non_young) { 6296 non_young_time_ms += elapsed_ms; 6297 } else { 6298 young_time_ms += elapsed_ms; 6299 } 6300 6301 prepend_to_freelist(&local_free_list); 6302 decrement_summary_bytes(pre_used); 6303 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms); 6304 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms); 6305 } 6306 6307 // This routine is similar to the above but does not record 6308 // any policy statistics or update free lists; we are abandoning 6309 // the current incremental collection set in preparation of a 6310 // full collection. After the full GC we will start to build up 6311 // the incremental collection set again. 6312 // This is only called when we're doing a full collection 6313 // and is immediately followed by the tearing down of the young list. 6314 6315 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) { 6316 HeapRegion* cur = cs_head; 6317 6318 while (cur != NULL) { 6319 HeapRegion* next = cur->next_in_collection_set(); 6320 assert(cur->in_collection_set(), "bad CS"); 6321 cur->set_next_in_collection_set(NULL); 6322 cur->set_in_collection_set(false); 6323 cur->set_young_index_in_cset(-1); 6324 cur = next; 6325 } 6326 } 6327 6328 void G1CollectedHeap::set_free_regions_coming() { 6329 if (G1ConcRegionFreeingVerbose) { 6330 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " 6331 "setting free regions coming"); 6332 } 6333 6334 assert(!free_regions_coming(), "pre-condition"); 6335 _free_regions_coming = true; 6336 } 6337 6338 void G1CollectedHeap::reset_free_regions_coming() { 6339 assert(free_regions_coming(), "pre-condition"); 6340 6341 { 6342 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6343 _free_regions_coming = false; 6344 SecondaryFreeList_lock->notify_all(); 6345 } 6346 6347 if (G1ConcRegionFreeingVerbose) { 6348 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " 6349 "reset free regions coming"); 6350 } 6351 } 6352 6353 void G1CollectedHeap::wait_while_free_regions_coming() { 6354 // Most of the time we won't have to wait, so let's do a quick test 6355 // first before we take the lock. 6356 if (!free_regions_coming()) { 6357 return; 6358 } 6359 6360 if (G1ConcRegionFreeingVerbose) { 6361 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " 6362 "waiting for free regions"); 6363 } 6364 6365 { 6366 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6367 while (free_regions_coming()) { 6368 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 6369 } 6370 } 6371 6372 if (G1ConcRegionFreeingVerbose) { 6373 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " 6374 "done waiting for free regions"); 6375 } 6376 } 6377 6378 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 6379 assert(heap_lock_held_for_gc(), 6380 "the heap lock should already be held by or for this thread"); 6381 _young_list->push_region(hr); 6382 } 6383 6384 class NoYoungRegionsClosure: public HeapRegionClosure { 6385 private: 6386 bool _success; 6387 public: 6388 NoYoungRegionsClosure() : _success(true) { } 6389 bool doHeapRegion(HeapRegion* r) { 6390 if (r->is_young()) { 6391 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young", 6392 r->bottom(), r->end()); 6393 _success = false; 6394 } 6395 return false; 6396 } 6397 bool success() { return _success; } 6398 }; 6399 6400 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) { 6401 bool ret = _young_list->check_list_empty(check_sample); 6402 6403 if (check_heap) { 6404 NoYoungRegionsClosure closure; 6405 heap_region_iterate(&closure); 6406 ret = ret && closure.success(); 6407 } 6408 6409 return ret; 6410 } 6411 6412 class TearDownRegionSetsClosure : public HeapRegionClosure { 6413 private: 6414 HeapRegionSet *_old_set; 6415 6416 public: 6417 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { } 6418 6419 bool doHeapRegion(HeapRegion* r) { 6420 if (r->is_empty()) { 6421 // We ignore empty regions, we'll empty the free list afterwards 6422 } else if (r->is_young()) { 6423 // We ignore young regions, we'll empty the young list afterwards 6424 } else if (r->isHumongous()) { 6425 // We ignore humongous regions, we're not tearing down the 6426 // humongous region set 6427 } else { 6428 // The rest should be old 6429 _old_set->remove(r); 6430 } 6431 return false; 6432 } 6433 6434 ~TearDownRegionSetsClosure() { 6435 assert(_old_set->is_empty(), "post-condition"); 6436 } 6437 }; 6438 6439 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) { 6440 assert_at_safepoint(true /* should_be_vm_thread */); 6441 6442 if (!free_list_only) { 6443 TearDownRegionSetsClosure cl(&_old_set); 6444 heap_region_iterate(&cl); 6445 6446 // Note that emptying the _young_list is postponed and instead done as 6447 // the first step when rebuilding the regions sets again. The reason for 6448 // this is that during a full GC string deduplication needs to know if 6449 // a collected region was young or old when the full GC was initiated. 6450 } 6451 _free_list.remove_all(); 6452 } 6453 6454 class RebuildRegionSetsClosure : public HeapRegionClosure { 6455 private: 6456 bool _free_list_only; 6457 HeapRegionSet* _old_set; 6458 FreeRegionList* _free_list; 6459 size_t _total_used; 6460 6461 public: 6462 RebuildRegionSetsClosure(bool free_list_only, 6463 HeapRegionSet* old_set, FreeRegionList* free_list) : 6464 _free_list_only(free_list_only), 6465 _old_set(old_set), _free_list(free_list), _total_used(0) { 6466 assert(_free_list->is_empty(), "pre-condition"); 6467 if (!free_list_only) { 6468 assert(_old_set->is_empty(), "pre-condition"); 6469 } 6470 } 6471 6472 bool doHeapRegion(HeapRegion* r) { 6473 if (r->continuesHumongous()) { 6474 return false; 6475 } 6476 6477 if (r->is_empty()) { 6478 // Add free regions to the free list 6479 _free_list->add_as_tail(r); 6480 } else if (!_free_list_only) { 6481 assert(!r->is_young(), "we should not come across young regions"); 6482 6483 if (r->isHumongous()) { 6484 // We ignore humongous regions, we left the humongous set unchanged 6485 } else { 6486 // The rest should be old, add them to the old set 6487 _old_set->add(r); 6488 } 6489 _total_used += r->used(); 6490 } 6491 6492 return false; 6493 } 6494 6495 size_t total_used() { 6496 return _total_used; 6497 } 6498 }; 6499 6500 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { 6501 assert_at_safepoint(true /* should_be_vm_thread */); 6502 6503 if (!free_list_only) { 6504 _young_list->empty_list(); 6505 } 6506 6507 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_free_list); 6508 heap_region_iterate(&cl); 6509 6510 if (!free_list_only) { 6511 _summary_bytes_used = cl.total_used(); 6512 } 6513 assert(_summary_bytes_used == recalculate_used(), 6514 err_msg("inconsistent _summary_bytes_used, " 6515 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT, 6516 _summary_bytes_used, recalculate_used())); 6517 } 6518 6519 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) { 6520 _refine_cte_cl->set_concurrent(concurrent); 6521 } 6522 6523 bool G1CollectedHeap::is_in_closed_subset(const void* p) const { 6524 HeapRegion* hr = heap_region_containing(p); 6525 return hr->is_in(p); 6526 } 6527 6528 // Methods for the mutator alloc region 6529 6530 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 6531 bool force) { 6532 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6533 assert(!force || g1_policy()->can_expand_young_list(), 6534 "if force is true we should be able to expand the young list"); 6535 bool young_list_full = g1_policy()->is_young_list_full(); 6536 if (force || !young_list_full) { 6537 HeapRegion* new_alloc_region = new_region(word_size, 6538 false /* is_old */, 6539 false /* do_expand */); 6540 if (new_alloc_region != NULL) { 6541 set_region_short_lived_locked(new_alloc_region); 6542 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full); 6543 check_bitmaps("Mutator Region Allocation", new_alloc_region); 6544 return new_alloc_region; 6545 } 6546 } 6547 return NULL; 6548 } 6549 6550 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 6551 size_t allocated_bytes) { 6552 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6553 assert(alloc_region->is_young(), "all mutator alloc regions should be young"); 6554 6555 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region); 6556 _summary_bytes_used += allocated_bytes; 6557 _hr_printer.retire(alloc_region); 6558 // We update the eden sizes here, when the region is retired, 6559 // instead of when it's allocated, since this is the point that its 6560 // used space has been recored in _summary_bytes_used. 6561 g1mm()->update_eden_size(); 6562 } 6563 6564 HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size, 6565 bool force) { 6566 return _g1h->new_mutator_alloc_region(word_size, force); 6567 } 6568 6569 void G1CollectedHeap::set_par_threads() { 6570 // Don't change the number of workers. Use the value previously set 6571 // in the workgroup. 6572 assert(G1CollectedHeap::use_parallel_gc_threads(), "shouldn't be here otherwise"); 6573 uint n_workers = workers()->active_workers(); 6574 assert(UseDynamicNumberOfGCThreads || 6575 n_workers == workers()->total_workers(), 6576 "Otherwise should be using the total number of workers"); 6577 if (n_workers == 0) { 6578 assert(false, "Should have been set in prior evacuation pause."); 6579 n_workers = ParallelGCThreads; 6580 workers()->set_active_workers(n_workers); 6581 } 6582 set_par_threads(n_workers); 6583 } 6584 6585 void MutatorAllocRegion::retire_region(HeapRegion* alloc_region, 6586 size_t allocated_bytes) { 6587 _g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes); 6588 } 6589 6590 // Methods for the GC alloc regions 6591 6592 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, 6593 uint count, 6594 GCAllocPurpose ap) { 6595 assert(FreeList_lock->owned_by_self(), "pre-condition"); 6596 6597 if (count < g1_policy()->max_regions(ap)) { 6598 bool survivor = (ap == GCAllocForSurvived); 6599 HeapRegion* new_alloc_region = new_region(word_size, 6600 !survivor, 6601 true /* do_expand */); 6602 if (new_alloc_region != NULL) { 6603 // We really only need to do this for old regions given that we 6604 // should never scan survivors. But it doesn't hurt to do it 6605 // for survivors too. 6606 new_alloc_region->set_saved_mark(); 6607 if (survivor) { 6608 new_alloc_region->set_survivor(); 6609 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor); 6610 check_bitmaps("Survivor Region Allocation", new_alloc_region); 6611 } else { 6612 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old); 6613 check_bitmaps("Old Region Allocation", new_alloc_region); 6614 } 6615 bool during_im = g1_policy()->during_initial_mark_pause(); 6616 new_alloc_region->note_start_of_copying(during_im); 6617 return new_alloc_region; 6618 } else { 6619 g1_policy()->note_alloc_region_limit_reached(ap); 6620 } 6621 } 6622 return NULL; 6623 } 6624 6625 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 6626 size_t allocated_bytes, 6627 GCAllocPurpose ap) { 6628 bool during_im = g1_policy()->during_initial_mark_pause(); 6629 alloc_region->note_end_of_copying(during_im); 6630 g1_policy()->record_bytes_copied_during_gc(allocated_bytes); 6631 if (ap == GCAllocForSurvived) { 6632 young_list()->add_survivor_region(alloc_region); 6633 } else { 6634 _old_set.add(alloc_region); 6635 } 6636 _hr_printer.retire(alloc_region); 6637 } 6638 6639 HeapRegion* SurvivorGCAllocRegion::allocate_new_region(size_t word_size, 6640 bool force) { 6641 assert(!force, "not supported for GC alloc regions"); 6642 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForSurvived); 6643 } 6644 6645 void SurvivorGCAllocRegion::retire_region(HeapRegion* alloc_region, 6646 size_t allocated_bytes) { 6647 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes, 6648 GCAllocForSurvived); 6649 } 6650 6651 HeapRegion* OldGCAllocRegion::allocate_new_region(size_t word_size, 6652 bool force) { 6653 assert(!force, "not supported for GC alloc regions"); 6654 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForTenured); 6655 } 6656 6657 void OldGCAllocRegion::retire_region(HeapRegion* alloc_region, 6658 size_t allocated_bytes) { 6659 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes, 6660 GCAllocForTenured); 6661 } 6662 // Heap region set verification 6663 6664 class VerifyRegionListsClosure : public HeapRegionClosure { 6665 private: 6666 HeapRegionSet* _old_set; 6667 HeapRegionSet* _humongous_set; 6668 FreeRegionList* _free_list; 6669 6670 public: 6671 HeapRegionSetCount _old_count; 6672 HeapRegionSetCount _humongous_count; 6673 HeapRegionSetCount _free_count; 6674 6675 VerifyRegionListsClosure(HeapRegionSet* old_set, 6676 HeapRegionSet* humongous_set, 6677 FreeRegionList* free_list) : 6678 _old_set(old_set), _humongous_set(humongous_set), _free_list(free_list), 6679 _old_count(), _humongous_count(), _free_count(){ } 6680 6681 bool doHeapRegion(HeapRegion* hr) { 6682 if (hr->continuesHumongous()) { 6683 return false; 6684 } 6685 6686 if (hr->is_young()) { 6687 // TODO 6688 } else if (hr->startsHumongous()) { 6689 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrs_index())); 6690 _humongous_count.increment(1u, hr->capacity()); 6691 } else if (hr->is_empty()) { 6692 assert(hr->containing_set() == _free_list, err_msg("Heap region %u is empty but not on the free list.", hr->hrs_index())); 6693 _free_count.increment(1u, hr->capacity()); 6694 } else { 6695 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrs_index())); 6696 _old_count.increment(1u, hr->capacity()); 6697 } 6698 return false; 6699 } 6700 6701 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, FreeRegionList* free_list) { 6702 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length())); 6703 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6704 old_set->total_capacity_bytes(), _old_count.capacity())); 6705 6706 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length())); 6707 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6708 humongous_set->total_capacity_bytes(), _humongous_count.capacity())); 6709 6710 guarantee(free_list->length() == _free_count.length(), err_msg("Free list count mismatch. Expected %u, actual %u.", free_list->length(), _free_count.length())); 6711 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6712 free_list->total_capacity_bytes(), _free_count.capacity())); 6713 } 6714 }; 6715 6716 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index, 6717 HeapWord* bottom) { 6718 HeapWord* end = bottom + HeapRegion::GrainWords; 6719 MemRegion mr(bottom, end); 6720 assert(_g1_reserved.contains(mr), "invariant"); 6721 // This might return NULL if the allocation fails 6722 return new HeapRegion(hrs_index, _bot_shared, mr); 6723 } 6724 6725 void G1CollectedHeap::verify_region_sets() { 6726 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6727 6728 // First, check the explicit lists. 6729 _free_list.verify_list(); 6730 { 6731 // Given that a concurrent operation might be adding regions to 6732 // the secondary free list we have to take the lock before 6733 // verifying it. 6734 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6735 _secondary_free_list.verify_list(); 6736 } 6737 6738 // If a concurrent region freeing operation is in progress it will 6739 // be difficult to correctly attributed any free regions we come 6740 // across to the correct free list given that they might belong to 6741 // one of several (free_list, secondary_free_list, any local lists, 6742 // etc.). So, if that's the case we will skip the rest of the 6743 // verification operation. Alternatively, waiting for the concurrent 6744 // operation to complete will have a non-trivial effect on the GC's 6745 // operation (no concurrent operation will last longer than the 6746 // interval between two calls to verification) and it might hide 6747 // any issues that we would like to catch during testing. 6748 if (free_regions_coming()) { 6749 return; 6750 } 6751 6752 // Make sure we append the secondary_free_list on the free_list so 6753 // that all free regions we will come across can be safely 6754 // attributed to the free_list. 6755 append_secondary_free_list_if_not_empty_with_lock(); 6756 6757 // Finally, make sure that the region accounting in the lists is 6758 // consistent with what we see in the heap. 6759 6760 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_free_list); 6761 heap_region_iterate(&cl); 6762 cl.verify_counts(&_old_set, &_humongous_set, &_free_list); 6763 } 6764 6765 // Optimized nmethod scanning 6766 6767 class RegisterNMethodOopClosure: public OopClosure { 6768 G1CollectedHeap* _g1h; 6769 nmethod* _nm; 6770 6771 template <class T> void do_oop_work(T* p) { 6772 T heap_oop = oopDesc::load_heap_oop(p); 6773 if (!oopDesc::is_null(heap_oop)) { 6774 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 6775 HeapRegion* hr = _g1h->heap_region_containing(obj); 6776 assert(!hr->continuesHumongous(), 6777 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT 6778 " starting at "HR_FORMAT, 6779 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()))); 6780 6781 // HeapRegion::add_strong_code_root() avoids adding duplicate 6782 // entries but having duplicates is OK since we "mark" nmethods 6783 // as visited when we scan the strong code root lists during the GC. 6784 hr->add_strong_code_root(_nm); 6785 assert(hr->rem_set()->strong_code_roots_list_contains(_nm), 6786 err_msg("failed to add code root "PTR_FORMAT" to remembered set of region "HR_FORMAT, 6787 _nm, HR_FORMAT_PARAMS(hr))); 6788 } 6789 } 6790 6791 public: 6792 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 6793 _g1h(g1h), _nm(nm) {} 6794 6795 void do_oop(oop* p) { do_oop_work(p); } 6796 void do_oop(narrowOop* p) { do_oop_work(p); } 6797 }; 6798 6799 class UnregisterNMethodOopClosure: public OopClosure { 6800 G1CollectedHeap* _g1h; 6801 nmethod* _nm; 6802 6803 template <class T> void do_oop_work(T* p) { 6804 T heap_oop = oopDesc::load_heap_oop(p); 6805 if (!oopDesc::is_null(heap_oop)) { 6806 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 6807 HeapRegion* hr = _g1h->heap_region_containing(obj); 6808 assert(!hr->continuesHumongous(), 6809 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT 6810 " starting at "HR_FORMAT, 6811 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()))); 6812 6813 hr->remove_strong_code_root(_nm); 6814 assert(!hr->rem_set()->strong_code_roots_list_contains(_nm), 6815 err_msg("failed to remove code root "PTR_FORMAT" of region "HR_FORMAT, 6816 _nm, HR_FORMAT_PARAMS(hr))); 6817 } 6818 } 6819 6820 public: 6821 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 6822 _g1h(g1h), _nm(nm) {} 6823 6824 void do_oop(oop* p) { do_oop_work(p); } 6825 void do_oop(narrowOop* p) { do_oop_work(p); } 6826 }; 6827 6828 void G1CollectedHeap::register_nmethod(nmethod* nm) { 6829 CollectedHeap::register_nmethod(nm); 6830 6831 guarantee(nm != NULL, "sanity"); 6832 RegisterNMethodOopClosure reg_cl(this, nm); 6833 nm->oops_do(®_cl); 6834 } 6835 6836 void G1CollectedHeap::unregister_nmethod(nmethod* nm) { 6837 CollectedHeap::unregister_nmethod(nm); 6838 6839 guarantee(nm != NULL, "sanity"); 6840 UnregisterNMethodOopClosure reg_cl(this, nm); 6841 nm->oops_do(®_cl, true); 6842 } 6843 6844 class MigrateCodeRootsHeapRegionClosure: public HeapRegionClosure { 6845 public: 6846 bool doHeapRegion(HeapRegion *hr) { 6847 assert(!hr->isHumongous(), 6848 err_msg("humongous region "HR_FORMAT" should not have been added to collection set", 6849 HR_FORMAT_PARAMS(hr))); 6850 hr->migrate_strong_code_roots(); 6851 return false; 6852 } 6853 }; 6854 6855 void G1CollectedHeap::migrate_strong_code_roots() { 6856 MigrateCodeRootsHeapRegionClosure cl; 6857 double migrate_start = os::elapsedTime(); 6858 collection_set_iterate(&cl); 6859 double migration_time_ms = (os::elapsedTime() - migrate_start) * 1000.0; 6860 g1_policy()->phase_times()->record_strong_code_root_migration_time(migration_time_ms); 6861 } 6862 6863 void G1CollectedHeap::purge_code_root_memory() { 6864 double purge_start = os::elapsedTime(); 6865 G1CodeRootSet::purge_chunks(G1CodeRootsChunkCacheKeepPercent); 6866 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0; 6867 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms); 6868 } 6869 6870 // Mark all the code roots that point into regions *not* in the 6871 // collection set. 6872 // 6873 // Note we do not want to use a "marking" CodeBlobToOopClosure while 6874 // walking the the code roots lists of regions not in the collection 6875 // set. Suppose we have an nmethod (M) that points to objects in two 6876 // separate regions - one in the collection set (R1) and one not (R2). 6877 // Using a "marking" CodeBlobToOopClosure here would result in "marking" 6878 // nmethod M when walking the code roots for R1. When we come to scan 6879 // the code roots for R2, we would see that M is already marked and it 6880 // would be skipped and the objects in R2 that are referenced from M 6881 // would not be evacuated. 6882 6883 class MarkStrongCodeRootCodeBlobClosure: public CodeBlobClosure { 6884 6885 class MarkStrongCodeRootOopClosure: public OopClosure { 6886 ConcurrentMark* _cm; 6887 HeapRegion* _hr; 6888 uint _worker_id; 6889 6890 template <class T> void do_oop_work(T* p) { 6891 T heap_oop = oopDesc::load_heap_oop(p); 6892 if (!oopDesc::is_null(heap_oop)) { 6893 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 6894 // Only mark objects in the region (which is assumed 6895 // to be not in the collection set). 6896 if (_hr->is_in(obj)) { 6897 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id); 6898 } 6899 } 6900 } 6901 6902 public: 6903 MarkStrongCodeRootOopClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id) : 6904 _cm(cm), _hr(hr), _worker_id(worker_id) { 6905 assert(!_hr->in_collection_set(), "sanity"); 6906 } 6907 6908 void do_oop(narrowOop* p) { do_oop_work(p); } 6909 void do_oop(oop* p) { do_oop_work(p); } 6910 }; 6911 6912 MarkStrongCodeRootOopClosure _oop_cl; 6913 6914 public: 6915 MarkStrongCodeRootCodeBlobClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id): 6916 _oop_cl(cm, hr, worker_id) {} 6917 6918 void do_code_blob(CodeBlob* cb) { 6919 nmethod* nm = (cb == NULL) ? NULL : cb->as_nmethod_or_null(); 6920 if (nm != NULL) { 6921 nm->oops_do(&_oop_cl); 6922 } 6923 } 6924 }; 6925 6926 class MarkStrongCodeRootsHRClosure: public HeapRegionClosure { 6927 G1CollectedHeap* _g1h; 6928 uint _worker_id; 6929 6930 public: 6931 MarkStrongCodeRootsHRClosure(G1CollectedHeap* g1h, uint worker_id) : 6932 _g1h(g1h), _worker_id(worker_id) {} 6933 6934 bool doHeapRegion(HeapRegion *hr) { 6935 HeapRegionRemSet* hrrs = hr->rem_set(); 6936 if (hr->continuesHumongous()) { 6937 // Code roots should never be attached to a continuation of a humongous region 6938 assert(hrrs->strong_code_roots_list_length() == 0, 6939 err_msg("code roots should never be attached to continuations of humongous region "HR_FORMAT 6940 " starting at "HR_FORMAT", but has "SIZE_FORMAT, 6941 HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()), 6942 hrrs->strong_code_roots_list_length())); 6943 return false; 6944 } 6945 6946 if (hr->in_collection_set()) { 6947 // Don't mark code roots into regions in the collection set here. 6948 // They will be marked when we scan them. 6949 return false; 6950 } 6951 6952 MarkStrongCodeRootCodeBlobClosure cb_cl(_g1h->concurrent_mark(), hr, _worker_id); 6953 hr->strong_code_roots_do(&cb_cl); 6954 return false; 6955 } 6956 }; 6957 6958 void G1CollectedHeap::mark_strong_code_roots(uint worker_id) { 6959 MarkStrongCodeRootsHRClosure cl(this, worker_id); 6960 if (G1CollectedHeap::use_parallel_gc_threads()) { 6961 heap_region_par_iterate_chunked(&cl, 6962 worker_id, 6963 workers()->active_workers(), 6964 HeapRegion::ParMarkRootClaimValue); 6965 } else { 6966 heap_region_iterate(&cl); 6967 } 6968 } 6969 6970 class RebuildStrongCodeRootClosure: public CodeBlobClosure { 6971 G1CollectedHeap* _g1h; 6972 6973 public: 6974 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) : 6975 _g1h(g1h) {} 6976 6977 void do_code_blob(CodeBlob* cb) { 6978 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL; 6979 if (nm == NULL) { 6980 return; 6981 } 6982 6983 if (ScavengeRootsInCode) { 6984 _g1h->register_nmethod(nm); 6985 } 6986 } 6987 }; 6988 6989 void G1CollectedHeap::rebuild_strong_code_roots() { 6990 RebuildStrongCodeRootClosure blob_cl(this); 6991 CodeCache::blobs_do(&blob_cl); 6992 }