1 /* 2 * Copyright (c) 2001, 2013, 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 #include "precompiled.hpp" 26 #include "code/icBuffer.hpp" 27 #include "gc_implementation/g1/bufferingOopClosure.hpp" 28 #include "gc_implementation/g1/concurrentG1Refine.hpp" 29 #include "gc_implementation/g1/concurrentG1RefineThread.hpp" 30 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp" 31 #include "gc_implementation/g1/g1AllocRegion.inline.hpp" 32 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp" 33 #include "gc_implementation/g1/g1CollectorPolicy.hpp" 34 #include "gc_implementation/g1/g1ErgoVerbose.hpp" 35 #include "gc_implementation/g1/g1EvacFailure.hpp" 36 #include "gc_implementation/g1/g1GCPhaseTimes.hpp" 37 #include "gc_implementation/g1/g1Log.hpp" 38 #include "gc_implementation/g1/g1MarkSweep.hpp" 39 #include "gc_implementation/g1/g1OopClosures.inline.hpp" 40 #include "gc_implementation/g1/g1RemSet.inline.hpp" 41 #include "gc_implementation/g1/heapRegion.inline.hpp" 42 #include "gc_implementation/g1/heapRegionRemSet.hpp" 43 #include "gc_implementation/g1/heapRegionSeq.inline.hpp" 44 #include "gc_implementation/g1/vm_operations_g1.hpp" 45 #include "gc_implementation/shared/isGCActiveMark.hpp" 46 #include "memory/gcLocker.inline.hpp" 47 #include "memory/genOopClosures.inline.hpp" 48 #include "memory/generationSpec.hpp" 49 #include "memory/referenceProcessor.hpp" 50 #include "oops/oop.inline.hpp" 51 #include "oops/oop.pcgc.inline.hpp" 52 #include "runtime/aprofiler.hpp" 53 #include "runtime/vmThread.hpp" 54 55 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0; 56 57 // turn it on so that the contents of the young list (scan-only / 58 // to-be-collected) are printed at "strategic" points before / during 59 // / after the collection --- this is useful for debugging 60 #define YOUNG_LIST_VERBOSE 0 61 // CURRENT STATUS 62 // This file is under construction. Search for "FIXME". 63 64 // INVARIANTS/NOTES 65 // 66 // All allocation activity covered by the G1CollectedHeap interface is 67 // serialized by acquiring the HeapLock. This happens in mem_allocate 68 // and allocate_new_tlab, which are the "entry" points to the 69 // allocation code from the rest of the JVM. (Note that this does not 70 // apply to TLAB allocation, which is not part of this interface: it 71 // is done by clients of this interface.) 72 73 // Notes on implementation of parallelism in different tasks. 74 // 75 // G1ParVerifyTask uses heap_region_par_iterate_chunked() for parallelism. 76 // The number of GC workers is passed to heap_region_par_iterate_chunked(). 77 // It does use run_task() which sets _n_workers in the task. 78 // G1ParTask executes g1_process_strong_roots() -> 79 // SharedHeap::process_strong_roots() which calls eventuall to 80 // CardTableModRefBS::par_non_clean_card_iterate_work() which uses 81 // SequentialSubTasksDone. SharedHeap::process_strong_roots() also 82 // directly uses SubTasksDone (_process_strong_tasks field in SharedHeap). 83 // 84 85 // Local to this file. 86 87 class RefineCardTableEntryClosure: public CardTableEntryClosure { 88 SuspendibleThreadSet* _sts; 89 G1RemSet* _g1rs; 90 ConcurrentG1Refine* _cg1r; 91 bool _concurrent; 92 public: 93 RefineCardTableEntryClosure(SuspendibleThreadSet* sts, 94 G1RemSet* g1rs, 95 ConcurrentG1Refine* cg1r) : 96 _sts(sts), _g1rs(g1rs), _cg1r(cg1r), _concurrent(true) 97 {} 98 bool do_card_ptr(jbyte* card_ptr, int worker_i) { 99 bool oops_into_cset = _g1rs->concurrentRefineOneCard(card_ptr, worker_i, false); 100 // This path is executed by the concurrent refine or mutator threads, 101 // concurrently, and so we do not care if card_ptr contains references 102 // that point into the collection set. 103 assert(!oops_into_cset, "should be"); 104 105 if (_concurrent && _sts->should_yield()) { 106 // Caller will actually yield. 107 return false; 108 } 109 // Otherwise, we finished successfully; return true. 110 return true; 111 } 112 void set_concurrent(bool b) { _concurrent = b; } 113 }; 114 115 116 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure { 117 int _calls; 118 G1CollectedHeap* _g1h; 119 CardTableModRefBS* _ctbs; 120 int _histo[256]; 121 public: 122 ClearLoggedCardTableEntryClosure() : 123 _calls(0) 124 { 125 _g1h = G1CollectedHeap::heap(); 126 _ctbs = (CardTableModRefBS*)_g1h->barrier_set(); 127 for (int i = 0; i < 256; i++) _histo[i] = 0; 128 } 129 bool do_card_ptr(jbyte* card_ptr, int worker_i) { 130 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) { 131 _calls++; 132 unsigned char* ujb = (unsigned char*)card_ptr; 133 int ind = (int)(*ujb); 134 _histo[ind]++; 135 *card_ptr = -1; 136 } 137 return true; 138 } 139 int calls() { return _calls; } 140 void print_histo() { 141 gclog_or_tty->print_cr("Card table value histogram:"); 142 for (int i = 0; i < 256; i++) { 143 if (_histo[i] != 0) { 144 gclog_or_tty->print_cr(" %d: %d", i, _histo[i]); 145 } 146 } 147 } 148 }; 149 150 class RedirtyLoggedCardTableEntryClosure: public CardTableEntryClosure { 151 int _calls; 152 G1CollectedHeap* _g1h; 153 CardTableModRefBS* _ctbs; 154 public: 155 RedirtyLoggedCardTableEntryClosure() : 156 _calls(0) 157 { 158 _g1h = G1CollectedHeap::heap(); 159 _ctbs = (CardTableModRefBS*)_g1h->barrier_set(); 160 } 161 bool do_card_ptr(jbyte* card_ptr, int worker_i) { 162 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) { 163 _calls++; 164 *card_ptr = 0; 165 } 166 return true; 167 } 168 int calls() { return _calls; } 169 }; 170 171 class RedirtyLoggedCardTableEntryFastClosure : public CardTableEntryClosure { 172 public: 173 bool do_card_ptr(jbyte* card_ptr, int worker_i) { 174 *card_ptr = CardTableModRefBS::dirty_card_val(); 175 return true; 176 } 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->print_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 void G1CollectedHeap::stop_conc_gc_threads() { 438 _cg1r->stop(); 439 _cmThread->stop(); 440 } 441 442 #ifdef ASSERT 443 // A region is added to the collection set as it is retired 444 // so an address p can point to a region which will be in the 445 // collection set but has not yet been retired. This method 446 // therefore is only accurate during a GC pause after all 447 // regions have been retired. It is used for debugging 448 // to check if an nmethod has references to objects that can 449 // be move during a partial collection. Though it can be 450 // inaccurate, it is sufficient for G1 because the conservative 451 // implementation of is_scavengable() for G1 will indicate that 452 // all nmethods must be scanned during a partial collection. 453 bool G1CollectedHeap::is_in_partial_collection(const void* p) { 454 HeapRegion* hr = heap_region_containing(p); 455 return hr != NULL && hr->in_collection_set(); 456 } 457 #endif 458 459 // Returns true if the reference points to an object that 460 // can move in an incremental collecction. 461 bool G1CollectedHeap::is_scavengable(const void* p) { 462 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 463 G1CollectorPolicy* g1p = g1h->g1_policy(); 464 HeapRegion* hr = heap_region_containing(p); 465 if (hr == NULL) { 466 // null 467 assert(p == NULL, err_msg("Not NULL " PTR_FORMAT ,p)); 468 return false; 469 } else { 470 return !hr->isHumongous(); 471 } 472 } 473 474 void G1CollectedHeap::check_ct_logs_at_safepoint() { 475 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 476 CardTableModRefBS* ct_bs = (CardTableModRefBS*)barrier_set(); 477 478 // Count the dirty cards at the start. 479 CountNonCleanMemRegionClosure count1(this); 480 ct_bs->mod_card_iterate(&count1); 481 int orig_count = count1.n(); 482 483 // First clear the logged cards. 484 ClearLoggedCardTableEntryClosure clear; 485 dcqs.set_closure(&clear); 486 dcqs.apply_closure_to_all_completed_buffers(); 487 dcqs.iterate_closure_all_threads(false); 488 clear.print_histo(); 489 490 // Now ensure that there's no dirty cards. 491 CountNonCleanMemRegionClosure count2(this); 492 ct_bs->mod_card_iterate(&count2); 493 if (count2.n() != 0) { 494 gclog_or_tty->print_cr("Card table has %d entries; %d originally", 495 count2.n(), orig_count); 496 } 497 guarantee(count2.n() == 0, "Card table should be clean."); 498 499 RedirtyLoggedCardTableEntryClosure redirty; 500 JavaThread::dirty_card_queue_set().set_closure(&redirty); 501 dcqs.apply_closure_to_all_completed_buffers(); 502 dcqs.iterate_closure_all_threads(false); 503 gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.", 504 clear.calls(), orig_count); 505 guarantee(redirty.calls() == clear.calls(), 506 "Or else mechanism is broken."); 507 508 CountNonCleanMemRegionClosure count3(this); 509 ct_bs->mod_card_iterate(&count3); 510 if (count3.n() != orig_count) { 511 gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.", 512 orig_count, count3.n()); 513 guarantee(count3.n() >= orig_count, "Should have restored them all."); 514 } 515 516 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl); 517 } 518 519 // Private class members. 520 521 G1CollectedHeap* G1CollectedHeap::_g1h; 522 523 // Private methods. 524 525 HeapRegion* 526 G1CollectedHeap::new_region_try_secondary_free_list() { 527 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 528 while (!_secondary_free_list.is_empty() || free_regions_coming()) { 529 if (!_secondary_free_list.is_empty()) { 530 if (G1ConcRegionFreeingVerbose) { 531 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 532 "secondary_free_list has %u entries", 533 _secondary_free_list.length()); 534 } 535 // It looks as if there are free regions available on the 536 // secondary_free_list. Let's move them to the free_list and try 537 // again to allocate from it. 538 append_secondary_free_list(); 539 540 assert(!_free_list.is_empty(), "if the secondary_free_list was not " 541 "empty we should have moved at least one entry to the free_list"); 542 HeapRegion* res = _free_list.remove_head(); 543 if (G1ConcRegionFreeingVerbose) { 544 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 545 "allocated "HR_FORMAT" from secondary_free_list", 546 HR_FORMAT_PARAMS(res)); 547 } 548 return res; 549 } 550 551 // Wait here until we get notifed either when (a) there are no 552 // more free regions coming or (b) some regions have been moved on 553 // the secondary_free_list. 554 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 555 } 556 557 if (G1ConcRegionFreeingVerbose) { 558 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 559 "could not allocate from secondary_free_list"); 560 } 561 return NULL; 562 } 563 564 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool do_expand) { 565 assert(!isHumongous(word_size) || word_size <= HeapRegion::GrainWords, 566 "the only time we use this to allocate a humongous region is " 567 "when we are allocating a single humongous region"); 568 569 HeapRegion* res; 570 if (G1StressConcRegionFreeing) { 571 if (!_secondary_free_list.is_empty()) { 572 if (G1ConcRegionFreeingVerbose) { 573 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 574 "forced to look at the secondary_free_list"); 575 } 576 res = new_region_try_secondary_free_list(); 577 if (res != NULL) { 578 return res; 579 } 580 } 581 } 582 res = _free_list.remove_head_or_null(); 583 if (res == NULL) { 584 if (G1ConcRegionFreeingVerbose) { 585 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 586 "res == NULL, trying the secondary_free_list"); 587 } 588 res = new_region_try_secondary_free_list(); 589 } 590 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) { 591 // Currently, only attempts to allocate GC alloc regions set 592 // do_expand to true. So, we should only reach here during a 593 // safepoint. If this assumption changes we might have to 594 // reconsider the use of _expand_heap_after_alloc_failure. 595 assert(SafepointSynchronize::is_at_safepoint(), "invariant"); 596 597 ergo_verbose1(ErgoHeapSizing, 598 "attempt heap expansion", 599 ergo_format_reason("region allocation request failed") 600 ergo_format_byte("allocation request"), 601 word_size * HeapWordSize); 602 if (expand(word_size * HeapWordSize)) { 603 // Given that expand() succeeded in expanding the heap, and we 604 // always expand the heap by an amount aligned to the heap 605 // region size, the free list should in theory not be empty. So 606 // it would probably be OK to use remove_head(). But the extra 607 // check for NULL is unlikely to be a performance issue here (we 608 // just expanded the heap!) so let's just be conservative and 609 // use remove_head_or_null(). 610 res = _free_list.remove_head_or_null(); 611 } else { 612 _expand_heap_after_alloc_failure = false; 613 } 614 } 615 return res; 616 } 617 618 uint G1CollectedHeap::humongous_obj_allocate_find_first(uint num_regions, 619 size_t word_size) { 620 assert(isHumongous(word_size), "word_size should be humongous"); 621 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition"); 622 623 uint first = G1_NULL_HRS_INDEX; 624 if (num_regions == 1) { 625 // Only one region to allocate, no need to go through the slower 626 // path. The caller will attempt the expasion if this fails, so 627 // let's not try to expand here too. 628 HeapRegion* hr = new_region(word_size, false /* do_expand */); 629 if (hr != NULL) { 630 first = hr->hrs_index(); 631 } else { 632 first = G1_NULL_HRS_INDEX; 633 } 634 } else { 635 // We can't allocate humongous regions while cleanupComplete() is 636 // running, since some of the regions we find to be empty might not 637 // yet be added to the free list and it is not straightforward to 638 // know which list they are on so that we can remove them. Note 639 // that we only need to do this if we need to allocate more than 640 // one region to satisfy the current humongous allocation 641 // request. If we are only allocating one region we use the common 642 // region allocation code (see above). 643 wait_while_free_regions_coming(); 644 append_secondary_free_list_if_not_empty_with_lock(); 645 646 if (free_regions() >= num_regions) { 647 first = _hrs.find_contiguous(num_regions); 648 if (first != G1_NULL_HRS_INDEX) { 649 for (uint i = first; i < first + num_regions; ++i) { 650 HeapRegion* hr = region_at(i); 651 assert(hr->is_empty(), "sanity"); 652 assert(is_on_master_free_list(hr), "sanity"); 653 hr->set_pending_removal(true); 654 } 655 _free_list.remove_all_pending(num_regions); 656 } 657 } 658 } 659 return first; 660 } 661 662 HeapWord* 663 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first, 664 uint num_regions, 665 size_t word_size) { 666 assert(first != G1_NULL_HRS_INDEX, "pre-condition"); 667 assert(isHumongous(word_size), "word_size should be humongous"); 668 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition"); 669 670 // Index of last region in the series + 1. 671 uint last = first + num_regions; 672 673 // We need to initialize the region(s) we just discovered. This is 674 // a bit tricky given that it can happen concurrently with 675 // refinement threads refining cards on these regions and 676 // potentially wanting to refine the BOT as they are scanning 677 // those cards (this can happen shortly after a cleanup; see CR 678 // 6991377). So we have to set up the region(s) carefully and in 679 // a specific order. 680 681 // The word size sum of all the regions we will allocate. 682 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords; 683 assert(word_size <= word_size_sum, "sanity"); 684 685 // This will be the "starts humongous" region. 686 HeapRegion* first_hr = region_at(first); 687 // The header of the new object will be placed at the bottom of 688 // the first region. 689 HeapWord* new_obj = first_hr->bottom(); 690 // This will be the new end of the first region in the series that 691 // should also match the end of the last region in the seriers. 692 HeapWord* new_end = new_obj + word_size_sum; 693 // This will be the new top of the first region that will reflect 694 // this allocation. 695 HeapWord* new_top = new_obj + word_size; 696 697 // First, we need to zero the header of the space that we will be 698 // allocating. When we update top further down, some refinement 699 // threads might try to scan the region. By zeroing the header we 700 // ensure that any thread that will try to scan the region will 701 // come across the zero klass word and bail out. 702 // 703 // NOTE: It would not have been correct to have used 704 // CollectedHeap::fill_with_object() and make the space look like 705 // an int array. The thread that is doing the allocation will 706 // later update the object header to a potentially different array 707 // type and, for a very short period of time, the klass and length 708 // fields will be inconsistent. This could cause a refinement 709 // thread to calculate the object size incorrectly. 710 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0); 711 712 // We will set up the first region as "starts humongous". This 713 // will also update the BOT covering all the regions to reflect 714 // that there is a single object that starts at the bottom of the 715 // first region. 716 first_hr->set_startsHumongous(new_top, new_end); 717 718 // Then, if there are any, we will set up the "continues 719 // humongous" regions. 720 HeapRegion* hr = NULL; 721 for (uint i = first + 1; i < last; ++i) { 722 hr = region_at(i); 723 hr->set_continuesHumongous(first_hr); 724 } 725 // If we have "continues humongous" regions (hr != NULL), then the 726 // end of the last one should match new_end. 727 assert(hr == NULL || hr->end() == new_end, "sanity"); 728 729 // Up to this point no concurrent thread would have been able to 730 // do any scanning on any region in this series. All the top 731 // fields still point to bottom, so the intersection between 732 // [bottom,top] and [card_start,card_end] will be empty. Before we 733 // update the top fields, we'll do a storestore to make sure that 734 // no thread sees the update to top before the zeroing of the 735 // object header and the BOT initialization. 736 OrderAccess::storestore(); 737 738 // Now that the BOT and the object header have been initialized, 739 // we can update top of the "starts humongous" region. 740 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(), 741 "new_top should be in this region"); 742 first_hr->set_top(new_top); 743 if (_hr_printer.is_active()) { 744 HeapWord* bottom = first_hr->bottom(); 745 HeapWord* end = first_hr->orig_end(); 746 if ((first + 1) == last) { 747 // the series has a single humongous region 748 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top); 749 } else { 750 // the series has more than one humongous regions 751 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end); 752 } 753 } 754 755 // Now, we will update the top fields of the "continues humongous" 756 // regions. The reason we need to do this is that, otherwise, 757 // these regions would look empty and this will confuse parts of 758 // G1. For example, the code that looks for a consecutive number 759 // of empty regions will consider them empty and try to 760 // re-allocate them. We can extend is_empty() to also include 761 // !continuesHumongous(), but it is easier to just update the top 762 // fields here. The way we set top for all regions (i.e., top == 763 // end for all regions but the last one, top == new_top for the 764 // last one) is actually used when we will free up the humongous 765 // region in free_humongous_region(). 766 hr = NULL; 767 for (uint i = first + 1; i < last; ++i) { 768 hr = region_at(i); 769 if ((i + 1) == last) { 770 // last continues humongous region 771 assert(hr->bottom() < new_top && new_top <= hr->end(), 772 "new_top should fall on this region"); 773 hr->set_top(new_top); 774 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top); 775 } else { 776 // not last one 777 assert(new_top > hr->end(), "new_top should be above this region"); 778 hr->set_top(hr->end()); 779 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end()); 780 } 781 } 782 // If we have continues humongous regions (hr != NULL), then the 783 // end of the last one should match new_end and its top should 784 // match new_top. 785 assert(hr == NULL || 786 (hr->end() == new_end && hr->top() == new_top), "sanity"); 787 788 assert(first_hr->used() == word_size * HeapWordSize, "invariant"); 789 _summary_bytes_used += first_hr->used(); 790 _humongous_set.add(first_hr); 791 792 return new_obj; 793 } 794 795 // If could fit into free regions w/o expansion, try. 796 // Otherwise, if can expand, do so. 797 // Otherwise, if using ex regions might help, try with ex given back. 798 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) { 799 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 800 801 verify_region_sets_optional(); 802 803 size_t word_size_rounded = round_to(word_size, HeapRegion::GrainWords); 804 uint num_regions = (uint) (word_size_rounded / HeapRegion::GrainWords); 805 uint x_num = expansion_regions(); 806 uint fs = _hrs.free_suffix(); 807 uint first = humongous_obj_allocate_find_first(num_regions, word_size); 808 if (first == G1_NULL_HRS_INDEX) { 809 // The only thing we can do now is attempt expansion. 810 if (fs + x_num >= num_regions) { 811 // If the number of regions we're trying to allocate for this 812 // object is at most the number of regions in the free suffix, 813 // then the call to humongous_obj_allocate_find_first() above 814 // should have succeeded and we wouldn't be here. 815 // 816 // We should only be trying to expand when the free suffix is 817 // not sufficient for the object _and_ we have some expansion 818 // room available. 819 assert(num_regions > fs, "earlier allocation should have succeeded"); 820 821 ergo_verbose1(ErgoHeapSizing, 822 "attempt heap expansion", 823 ergo_format_reason("humongous allocation request failed") 824 ergo_format_byte("allocation request"), 825 word_size * HeapWordSize); 826 if (expand((num_regions - fs) * HeapRegion::GrainBytes)) { 827 // Even though the heap was expanded, it might not have 828 // reached the desired size. So, we cannot assume that the 829 // allocation will succeed. 830 first = humongous_obj_allocate_find_first(num_regions, word_size); 831 } 832 } 833 } 834 835 HeapWord* result = NULL; 836 if (first != G1_NULL_HRS_INDEX) { 837 result = 838 humongous_obj_allocate_initialize_regions(first, num_regions, word_size); 839 assert(result != NULL, "it should always return a valid result"); 840 841 // A successful humongous object allocation changes the used space 842 // information of the old generation so we need to recalculate the 843 // sizes and update the jstat counters here. 844 g1mm()->update_sizes(); 845 } 846 847 verify_region_sets_optional(); 848 849 return result; 850 } 851 852 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) { 853 assert_heap_not_locked_and_not_at_safepoint(); 854 assert(!isHumongous(word_size), "we do not allow humongous TLABs"); 855 856 unsigned int dummy_gc_count_before; 857 int dummy_gclocker_retry_count = 0; 858 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count); 859 } 860 861 HeapWord* 862 G1CollectedHeap::mem_allocate(size_t word_size, 863 bool* gc_overhead_limit_was_exceeded) { 864 assert_heap_not_locked_and_not_at_safepoint(); 865 866 // Loop until the allocation is satisified, or unsatisfied after GC. 867 for (int try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 868 unsigned int gc_count_before; 869 870 HeapWord* result = NULL; 871 if (!isHumongous(word_size)) { 872 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count); 873 } else { 874 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count); 875 } 876 if (result != NULL) { 877 return result; 878 } 879 880 // Create the garbage collection operation... 881 VM_G1CollectForAllocation op(gc_count_before, word_size); 882 // ...and get the VM thread to execute it. 883 VMThread::execute(&op); 884 885 if (op.prologue_succeeded() && op.pause_succeeded()) { 886 // If the operation was successful we'll return the result even 887 // if it is NULL. If the allocation attempt failed immediately 888 // after a Full GC, it's unlikely we'll be able to allocate now. 889 HeapWord* result = op.result(); 890 if (result != NULL && !isHumongous(word_size)) { 891 // Allocations that take place on VM operations do not do any 892 // card dirtying and we have to do it here. We only have to do 893 // this for non-humongous allocations, though. 894 dirty_young_block(result, word_size); 895 } 896 return result; 897 } else { 898 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 899 return NULL; 900 } 901 assert(op.result() == NULL, 902 "the result should be NULL if the VM op did not succeed"); 903 } 904 905 // Give a warning if we seem to be looping forever. 906 if ((QueuedAllocationWarningCount > 0) && 907 (try_count % QueuedAllocationWarningCount == 0)) { 908 warning("G1CollectedHeap::mem_allocate retries %d times", try_count); 909 } 910 } 911 912 ShouldNotReachHere(); 913 return NULL; 914 } 915 916 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size, 917 unsigned int *gc_count_before_ret, 918 int* gclocker_retry_count_ret) { 919 // Make sure you read the note in attempt_allocation_humongous(). 920 921 assert_heap_not_locked_and_not_at_safepoint(); 922 assert(!isHumongous(word_size), "attempt_allocation_slow() should not " 923 "be called for humongous allocation requests"); 924 925 // We should only get here after the first-level allocation attempt 926 // (attempt_allocation()) failed to allocate. 927 928 // We will loop until a) we manage to successfully perform the 929 // allocation or b) we successfully schedule a collection which 930 // fails to perform the allocation. b) is the only case when we'll 931 // return NULL. 932 HeapWord* result = NULL; 933 for (int try_count = 1; /* we'll return */; try_count += 1) { 934 bool should_try_gc; 935 unsigned int gc_count_before; 936 937 { 938 MutexLockerEx x(Heap_lock); 939 940 result = _mutator_alloc_region.attempt_allocation_locked(word_size, 941 false /* bot_updates */); 942 if (result != NULL) { 943 return result; 944 } 945 946 // If we reach here, attempt_allocation_locked() above failed to 947 // allocate a new region. So the mutator alloc region should be NULL. 948 assert(_mutator_alloc_region.get() == NULL, "only way to get here"); 949 950 if (GC_locker::is_active_and_needs_gc()) { 951 if (g1_policy()->can_expand_young_list()) { 952 // No need for an ergo verbose message here, 953 // can_expand_young_list() does this when it returns true. 954 result = _mutator_alloc_region.attempt_allocation_force(word_size, 955 false /* bot_updates */); 956 if (result != NULL) { 957 return result; 958 } 959 } 960 should_try_gc = false; 961 } else { 962 // The GCLocker may not be active but the GCLocker initiated 963 // GC may not yet have been performed (GCLocker::needs_gc() 964 // returns true). In this case we do not try this GC and 965 // wait until the GCLocker initiated GC is performed, and 966 // then retry the allocation. 967 if (GC_locker::needs_gc()) { 968 should_try_gc = false; 969 } else { 970 // Read the GC count while still holding the Heap_lock. 971 gc_count_before = total_collections(); 972 should_try_gc = true; 973 } 974 } 975 } 976 977 if (should_try_gc) { 978 bool succeeded; 979 result = do_collection_pause(word_size, gc_count_before, &succeeded); 980 if (result != NULL) { 981 assert(succeeded, "only way to get back a non-NULL result"); 982 return result; 983 } 984 985 if (succeeded) { 986 // If we get here we successfully scheduled a collection which 987 // failed to allocate. No point in trying to allocate 988 // further. We'll just return NULL. 989 MutexLockerEx x(Heap_lock); 990 *gc_count_before_ret = total_collections(); 991 return NULL; 992 } 993 } else { 994 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { 995 MutexLockerEx x(Heap_lock); 996 *gc_count_before_ret = total_collections(); 997 return NULL; 998 } 999 // The GCLocker is either active or the GCLocker initiated 1000 // GC has not yet been performed. Stall until it is and 1001 // then retry the allocation. 1002 GC_locker::stall_until_clear(); 1003 (*gclocker_retry_count_ret) += 1; 1004 } 1005 1006 // We can reach here if we were unsuccessul in scheduling a 1007 // collection (because another thread beat us to it) or if we were 1008 // stalled due to the GC locker. In either can we should retry the 1009 // allocation attempt in case another thread successfully 1010 // performed a collection and reclaimed enough space. We do the 1011 // first attempt (without holding the Heap_lock) here and the 1012 // follow-on attempt will be at the start of the next loop 1013 // iteration (after taking the Heap_lock). 1014 result = _mutator_alloc_region.attempt_allocation(word_size, 1015 false /* bot_updates */); 1016 if (result != NULL) { 1017 return result; 1018 } 1019 1020 // Give a warning if we seem to be looping forever. 1021 if ((QueuedAllocationWarningCount > 0) && 1022 (try_count % QueuedAllocationWarningCount == 0)) { 1023 warning("G1CollectedHeap::attempt_allocation_slow() " 1024 "retries %d times", try_count); 1025 } 1026 } 1027 1028 ShouldNotReachHere(); 1029 return NULL; 1030 } 1031 1032 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size, 1033 unsigned int * gc_count_before_ret, 1034 int* gclocker_retry_count_ret) { 1035 // The structure of this method has a lot of similarities to 1036 // attempt_allocation_slow(). The reason these two were not merged 1037 // into a single one is that such a method would require several "if 1038 // allocation is not humongous do this, otherwise do that" 1039 // conditional paths which would obscure its flow. In fact, an early 1040 // version of this code did use a unified method which was harder to 1041 // follow and, as a result, it had subtle bugs that were hard to 1042 // track down. So keeping these two methods separate allows each to 1043 // be more readable. It will be good to keep these two in sync as 1044 // much as possible. 1045 1046 assert_heap_not_locked_and_not_at_safepoint(); 1047 assert(isHumongous(word_size), "attempt_allocation_humongous() " 1048 "should only be called for humongous allocations"); 1049 1050 // Humongous objects can exhaust the heap quickly, so we should check if we 1051 // need to start a marking cycle at each humongous object allocation. We do 1052 // the check before we do the actual allocation. The reason for doing it 1053 // before the allocation is that we avoid having to keep track of the newly 1054 // allocated memory while we do a GC. 1055 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation", 1056 word_size)) { 1057 collect(GCCause::_g1_humongous_allocation); 1058 } 1059 1060 // We will loop until a) we manage to successfully perform the 1061 // allocation or b) we successfully schedule a collection which 1062 // fails to perform the allocation. b) is the only case when we'll 1063 // return NULL. 1064 HeapWord* result = NULL; 1065 for (int try_count = 1; /* we'll return */; try_count += 1) { 1066 bool should_try_gc; 1067 unsigned int gc_count_before; 1068 1069 { 1070 MutexLockerEx x(Heap_lock); 1071 1072 // Given that humongous objects are not allocated in young 1073 // regions, we'll first try to do the allocation without doing a 1074 // collection hoping that there's enough space in the heap. 1075 result = humongous_obj_allocate(word_size); 1076 if (result != NULL) { 1077 return result; 1078 } 1079 1080 if (GC_locker::is_active_and_needs_gc()) { 1081 should_try_gc = false; 1082 } else { 1083 // The GCLocker may not be active but the GCLocker initiated 1084 // GC may not yet have been performed (GCLocker::needs_gc() 1085 // returns true). In this case we do not try this GC and 1086 // wait until the GCLocker initiated GC is performed, and 1087 // then retry the allocation. 1088 if (GC_locker::needs_gc()) { 1089 should_try_gc = false; 1090 } else { 1091 // Read the GC count while still holding the Heap_lock. 1092 gc_count_before = total_collections(); 1093 should_try_gc = true; 1094 } 1095 } 1096 } 1097 1098 if (should_try_gc) { 1099 // If we failed to allocate the humongous object, we should try to 1100 // do a collection pause (if we're allowed) in case it reclaims 1101 // enough space for the allocation to succeed after the pause. 1102 1103 bool succeeded; 1104 result = do_collection_pause(word_size, gc_count_before, &succeeded); 1105 if (result != NULL) { 1106 assert(succeeded, "only way to get back a non-NULL result"); 1107 return result; 1108 } 1109 1110 if (succeeded) { 1111 // If we get here we successfully scheduled a collection which 1112 // failed to allocate. No point in trying to allocate 1113 // further. We'll just return NULL. 1114 MutexLockerEx x(Heap_lock); 1115 *gc_count_before_ret = total_collections(); 1116 return NULL; 1117 } 1118 } else { 1119 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { 1120 MutexLockerEx x(Heap_lock); 1121 *gc_count_before_ret = total_collections(); 1122 return NULL; 1123 } 1124 // The GCLocker is either active or the GCLocker initiated 1125 // GC has not yet been performed. Stall until it is and 1126 // then retry the allocation. 1127 GC_locker::stall_until_clear(); 1128 (*gclocker_retry_count_ret) += 1; 1129 } 1130 1131 // We can reach here if we were unsuccessul in scheduling a 1132 // collection (because another thread beat us to it) or if we were 1133 // stalled due to the GC locker. In either can we should retry the 1134 // allocation attempt in case another thread successfully 1135 // performed a collection and reclaimed enough space. Give a 1136 // warning if we seem to be looping forever. 1137 1138 if ((QueuedAllocationWarningCount > 0) && 1139 (try_count % QueuedAllocationWarningCount == 0)) { 1140 warning("G1CollectedHeap::attempt_allocation_humongous() " 1141 "retries %d times", try_count); 1142 } 1143 } 1144 1145 ShouldNotReachHere(); 1146 return NULL; 1147 } 1148 1149 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size, 1150 bool expect_null_mutator_alloc_region) { 1151 assert_at_safepoint(true /* should_be_vm_thread */); 1152 assert(_mutator_alloc_region.get() == NULL || 1153 !expect_null_mutator_alloc_region, 1154 "the current alloc region was unexpectedly found to be non-NULL"); 1155 1156 if (!isHumongous(word_size)) { 1157 return _mutator_alloc_region.attempt_allocation_locked(word_size, 1158 false /* bot_updates */); 1159 } else { 1160 HeapWord* result = humongous_obj_allocate(word_size); 1161 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) { 1162 g1_policy()->set_initiate_conc_mark_if_possible(); 1163 } 1164 return result; 1165 } 1166 1167 ShouldNotReachHere(); 1168 } 1169 1170 class PostMCRemSetClearClosure: public HeapRegionClosure { 1171 G1CollectedHeap* _g1h; 1172 ModRefBarrierSet* _mr_bs; 1173 public: 1174 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) : 1175 _g1h(g1h), _mr_bs(mr_bs) { } 1176 bool doHeapRegion(HeapRegion* r) { 1177 if (r->continuesHumongous()) { 1178 return false; 1179 } 1180 _g1h->reset_gc_time_stamps(r); 1181 HeapRegionRemSet* hrrs = r->rem_set(); 1182 if (hrrs != NULL) hrrs->clear(); 1183 // You might think here that we could clear just the cards 1184 // corresponding to the used region. But no: if we leave a dirty card 1185 // in a region we might allocate into, then it would prevent that card 1186 // from being enqueued, and cause it to be missed. 1187 // Re: the performance cost: we shouldn't be doing full GC anyway! 1188 _mr_bs->clear(MemRegion(r->bottom(), r->end())); 1189 return false; 1190 } 1191 }; 1192 1193 void G1CollectedHeap::clear_rsets_post_compaction() { 1194 PostMCRemSetClearClosure rs_clear(this, mr_bs()); 1195 heap_region_iterate(&rs_clear); 1196 } 1197 1198 class RebuildRSOutOfRegionClosure: public HeapRegionClosure { 1199 G1CollectedHeap* _g1h; 1200 UpdateRSOopClosure _cl; 1201 int _worker_i; 1202 public: 1203 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) : 1204 _cl(g1->g1_rem_set(), worker_i), 1205 _worker_i(worker_i), 1206 _g1h(g1) 1207 { } 1208 1209 bool doHeapRegion(HeapRegion* r) { 1210 if (!r->continuesHumongous()) { 1211 _cl.set_from(r); 1212 r->oop_iterate(&_cl); 1213 } 1214 return false; 1215 } 1216 }; 1217 1218 class ParRebuildRSTask: public AbstractGangTask { 1219 G1CollectedHeap* _g1; 1220 public: 1221 ParRebuildRSTask(G1CollectedHeap* g1) 1222 : AbstractGangTask("ParRebuildRSTask"), 1223 _g1(g1) 1224 { } 1225 1226 void work(uint worker_id) { 1227 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id); 1228 _g1->heap_region_par_iterate_chunked(&rebuild_rs, worker_id, 1229 _g1->workers()->active_workers(), 1230 HeapRegion::RebuildRSClaimValue); 1231 } 1232 }; 1233 1234 class PostCompactionPrinterClosure: public HeapRegionClosure { 1235 private: 1236 G1HRPrinter* _hr_printer; 1237 public: 1238 bool doHeapRegion(HeapRegion* hr) { 1239 assert(!hr->is_young(), "not expecting to find young regions"); 1240 // We only generate output for non-empty regions. 1241 if (!hr->is_empty()) { 1242 if (!hr->isHumongous()) { 1243 _hr_printer->post_compaction(hr, G1HRPrinter::Old); 1244 } else if (hr->startsHumongous()) { 1245 if (hr->region_num() == 1) { 1246 // single humongous region 1247 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous); 1248 } else { 1249 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous); 1250 } 1251 } else { 1252 assert(hr->continuesHumongous(), "only way to get here"); 1253 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous); 1254 } 1255 } 1256 return false; 1257 } 1258 1259 PostCompactionPrinterClosure(G1HRPrinter* hr_printer) 1260 : _hr_printer(hr_printer) { } 1261 }; 1262 1263 void G1CollectedHeap::print_hrs_post_compaction() { 1264 PostCompactionPrinterClosure cl(hr_printer()); 1265 heap_region_iterate(&cl); 1266 } 1267 1268 double G1CollectedHeap::verify(bool guard, const char* msg) { 1269 double verify_time_ms = 0.0; 1270 1271 if (guard && total_collections() >= VerifyGCStartAt) { 1272 double verify_start = os::elapsedTime(); 1273 HandleMark hm; // Discard invalid handles created during verification 1274 prepare_for_verify(); 1275 Universe::verify(VerifyOption_G1UsePrevMarking, msg); 1276 verify_time_ms = (os::elapsedTime() - verify_start) * 1000; 1277 } 1278 1279 return verify_time_ms; 1280 } 1281 1282 void G1CollectedHeap::verify_before_gc() { 1283 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:"); 1284 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms); 1285 } 1286 1287 void G1CollectedHeap::verify_after_gc() { 1288 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:"); 1289 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms); 1290 } 1291 1292 bool G1CollectedHeap::do_collection(bool explicit_gc, 1293 bool clear_all_soft_refs, 1294 size_t word_size) { 1295 assert_at_safepoint(true /* should_be_vm_thread */); 1296 1297 if (GC_locker::check_active_before_gc()) { 1298 return false; 1299 } 1300 1301 SvcGCMarker sgcm(SvcGCMarker::FULL); 1302 ResourceMark rm; 1303 1304 print_heap_before_gc(); 1305 1306 size_t metadata_prev_used = MetaspaceAux::allocated_used_bytes(); 1307 1308 HRSPhaseSetter x(HRSPhaseFullGC); 1309 verify_region_sets_optional(); 1310 1311 const bool do_clear_all_soft_refs = clear_all_soft_refs || 1312 collector_policy()->should_clear_all_soft_refs(); 1313 1314 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy()); 1315 1316 { 1317 IsGCActiveMark x; 1318 1319 // Timing 1320 assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant"); 1321 gclog_or_tty->date_stamp(G1Log::fine() && PrintGCDateStamps); 1322 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty); 1323 1324 { 1325 TraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, gclog_or_tty); 1326 TraceCollectorStats tcs(g1mm()->full_collection_counters()); 1327 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause()); 1328 1329 double start = os::elapsedTime(); 1330 g1_policy()->record_full_collection_start(); 1331 1332 // Note: When we have a more flexible GC logging framework that 1333 // allows us to add optional attributes to a GC log record we 1334 // could consider timing and reporting how long we wait in the 1335 // following two methods. 1336 wait_while_free_regions_coming(); 1337 // If we start the compaction before the CM threads finish 1338 // scanning the root regions we might trip them over as we'll 1339 // be moving objects / updating references. So let's wait until 1340 // they are done. By telling them to abort, they should complete 1341 // early. 1342 _cm->root_regions()->abort(); 1343 _cm->root_regions()->wait_until_scan_finished(); 1344 append_secondary_free_list_if_not_empty_with_lock(); 1345 1346 gc_prologue(true); 1347 increment_total_collections(true /* full gc */); 1348 increment_old_marking_cycles_started(); 1349 1350 assert(used() == recalculate_used(), "Should be equal"); 1351 1352 verify_before_gc(); 1353 1354 pre_full_gc_dump(); 1355 1356 COMPILER2_PRESENT(DerivedPointerTable::clear()); 1357 1358 // Disable discovery and empty the discovered lists 1359 // for the CM ref processor. 1360 ref_processor_cm()->disable_discovery(); 1361 ref_processor_cm()->abandon_partial_discovery(); 1362 ref_processor_cm()->verify_no_references_recorded(); 1363 1364 // Abandon current iterations of concurrent marking and concurrent 1365 // refinement, if any are in progress. We have to do this before 1366 // wait_until_scan_finished() below. 1367 concurrent_mark()->abort(); 1368 1369 // Make sure we'll choose a new allocation region afterwards. 1370 release_mutator_alloc_region(); 1371 abandon_gc_alloc_regions(); 1372 g1_rem_set()->cleanupHRRS(); 1373 1374 // We should call this after we retire any currently active alloc 1375 // regions so that all the ALLOC / RETIRE events are generated 1376 // before the start GC event. 1377 _hr_printer.start_gc(true /* full */, (size_t) total_collections()); 1378 1379 // We may have added regions to the current incremental collection 1380 // set between the last GC or pause and now. We need to clear the 1381 // incremental collection set and then start rebuilding it afresh 1382 // after this full GC. 1383 abandon_collection_set(g1_policy()->inc_cset_head()); 1384 g1_policy()->clear_incremental_cset(); 1385 g1_policy()->stop_incremental_cset_building(); 1386 1387 tear_down_region_sets(false /* free_list_only */); 1388 g1_policy()->set_gcs_are_young(true); 1389 1390 // See the comments in g1CollectedHeap.hpp and 1391 // G1CollectedHeap::ref_processing_init() about 1392 // how reference processing currently works in G1. 1393 1394 // Temporarily make discovery by the STW ref processor single threaded (non-MT). 1395 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false); 1396 1397 // Temporarily clear the STW ref processor's _is_alive_non_header field. 1398 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL); 1399 1400 ref_processor_stw()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/); 1401 ref_processor_stw()->setup_policy(do_clear_all_soft_refs); 1402 1403 // Do collection work 1404 { 1405 HandleMark hm; // Discard invalid handles created during gc 1406 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs); 1407 } 1408 1409 assert(free_regions() == 0, "we should not have added any free regions"); 1410 rebuild_region_sets(false /* free_list_only */); 1411 1412 // Enqueue any discovered reference objects that have 1413 // not been removed from the discovered lists. 1414 ref_processor_stw()->enqueue_discovered_references(); 1415 1416 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 1417 1418 MemoryService::track_memory_usage(); 1419 1420 verify_after_gc(); 1421 1422 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 1423 ref_processor_stw()->verify_no_references_recorded(); 1424 1425 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 1426 ClassLoaderDataGraph::purge(); 1427 MetaspaceAux::verify_metrics(); 1428 1429 // Note: since we've just done a full GC, concurrent 1430 // marking is no longer active. Therefore we need not 1431 // re-enable reference discovery for the CM ref processor. 1432 // That will be done at the start of the next marking cycle. 1433 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition"); 1434 ref_processor_cm()->verify_no_references_recorded(); 1435 1436 reset_gc_time_stamp(); 1437 // Since everything potentially moved, we will clear all remembered 1438 // sets, and clear all cards. Later we will rebuild remebered 1439 // sets. We will also reset the GC time stamps of the regions. 1440 clear_rsets_post_compaction(); 1441 check_gc_time_stamps(); 1442 1443 // Resize the heap if necessary. 1444 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size); 1445 1446 if (_hr_printer.is_active()) { 1447 // We should do this after we potentially resize the heap so 1448 // that all the COMMIT / UNCOMMIT events are generated before 1449 // the end GC event. 1450 1451 print_hrs_post_compaction(); 1452 _hr_printer.end_gc(true /* full */, (size_t) total_collections()); 1453 } 1454 1455 if (_cg1r->use_cache()) { 1456 _cg1r->clear_and_record_card_counts(); 1457 _cg1r->clear_hot_cache(); 1458 } 1459 1460 // Rebuild remembered sets of all regions. 1461 if (G1CollectedHeap::use_parallel_gc_threads()) { 1462 uint n_workers = 1463 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 1464 workers()->active_workers(), 1465 Threads::number_of_non_daemon_threads()); 1466 assert(UseDynamicNumberOfGCThreads || 1467 n_workers == workers()->total_workers(), 1468 "If not dynamic should be using all the workers"); 1469 workers()->set_active_workers(n_workers); 1470 // Set parallel threads in the heap (_n_par_threads) only 1471 // before a parallel phase and always reset it to 0 after 1472 // the phase so that the number of parallel threads does 1473 // no get carried forward to a serial phase where there 1474 // may be code that is "possibly_parallel". 1475 set_par_threads(n_workers); 1476 1477 ParRebuildRSTask rebuild_rs_task(this); 1478 assert(check_heap_region_claim_values( 1479 HeapRegion::InitialClaimValue), "sanity check"); 1480 assert(UseDynamicNumberOfGCThreads || 1481 workers()->active_workers() == workers()->total_workers(), 1482 "Unless dynamic should use total workers"); 1483 // Use the most recent number of active workers 1484 assert(workers()->active_workers() > 0, 1485 "Active workers not properly set"); 1486 set_par_threads(workers()->active_workers()); 1487 workers()->run_task(&rebuild_rs_task); 1488 set_par_threads(0); 1489 assert(check_heap_region_claim_values( 1490 HeapRegion::RebuildRSClaimValue), "sanity check"); 1491 reset_heap_region_claim_values(); 1492 } else { 1493 RebuildRSOutOfRegionClosure rebuild_rs(this); 1494 heap_region_iterate(&rebuild_rs); 1495 } 1496 1497 if (true) { // FIXME 1498 MetaspaceGC::compute_new_size(); 1499 } 1500 1501 #ifdef TRACESPINNING 1502 ParallelTaskTerminator::print_termination_counts(); 1503 #endif 1504 1505 // Discard all rset updates 1506 JavaThread::dirty_card_queue_set().abandon_logs(); 1507 assert(!G1DeferredRSUpdate 1508 || (G1DeferredRSUpdate && 1509 (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any"); 1510 1511 _young_list->reset_sampled_info(); 1512 // At this point there should be no regions in the 1513 // entire heap tagged as young. 1514 assert(check_young_list_empty(true /* check_heap */), 1515 "young list should be empty at this point"); 1516 1517 // Update the number of full collections that have been completed. 1518 increment_old_marking_cycles_completed(false /* concurrent */); 1519 1520 _hrs.verify_optional(); 1521 verify_region_sets_optional(); 1522 1523 // Start a new incremental collection set for the next pause 1524 assert(g1_policy()->collection_set() == NULL, "must be"); 1525 g1_policy()->start_incremental_cset_building(); 1526 1527 // Clear the _cset_fast_test bitmap in anticipation of adding 1528 // regions to the incremental collection set for the next 1529 // evacuation pause. 1530 clear_cset_fast_test(); 1531 1532 init_mutator_alloc_region(); 1533 1534 double end = os::elapsedTime(); 1535 g1_policy()->record_full_collection_end(); 1536 1537 if (G1Log::fine()) { 1538 g1_policy()->print_heap_transition(); 1539 } 1540 1541 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 1542 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 1543 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 1544 // before any GC notifications are raised. 1545 g1mm()->update_sizes(); 1546 1547 gc_epilogue(true); 1548 } 1549 1550 if (G1Log::finer()) { 1551 g1_policy()->print_detailed_heap_transition(); 1552 } 1553 1554 print_heap_after_gc(); 1555 1556 post_full_gc_dump(); 1557 } 1558 1559 return true; 1560 } 1561 1562 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) { 1563 // do_collection() will return whether it succeeded in performing 1564 // the GC. Currently, there is no facility on the 1565 // do_full_collection() API to notify the caller than the collection 1566 // did not succeed (e.g., because it was locked out by the GC 1567 // locker). So, right now, we'll ignore the return value. 1568 bool dummy = do_collection(true, /* explicit_gc */ 1569 clear_all_soft_refs, 1570 0 /* word_size */); 1571 } 1572 1573 // This code is mostly copied from TenuredGeneration. 1574 void 1575 G1CollectedHeap:: 1576 resize_if_necessary_after_full_collection(size_t word_size) { 1577 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, "sanity check"); 1578 1579 // Include the current allocation, if any, and bytes that will be 1580 // pre-allocated to support collections, as "used". 1581 const size_t used_after_gc = used(); 1582 const size_t capacity_after_gc = capacity(); 1583 const size_t free_after_gc = capacity_after_gc - used_after_gc; 1584 1585 // This is enforced in arguments.cpp. 1586 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, 1587 "otherwise the code below doesn't make sense"); 1588 1589 // We don't have floating point command-line arguments 1590 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0; 1591 const double maximum_used_percentage = 1.0 - minimum_free_percentage; 1592 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0; 1593 const double minimum_used_percentage = 1.0 - maximum_free_percentage; 1594 1595 const size_t min_heap_size = collector_policy()->min_heap_byte_size(); 1596 const size_t max_heap_size = collector_policy()->max_heap_byte_size(); 1597 1598 // We have to be careful here as these two calculations can overflow 1599 // 32-bit size_t's. 1600 double used_after_gc_d = (double) used_after_gc; 1601 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage; 1602 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage; 1603 1604 // Let's make sure that they are both under the max heap size, which 1605 // by default will make them fit into a size_t. 1606 double desired_capacity_upper_bound = (double) max_heap_size; 1607 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d, 1608 desired_capacity_upper_bound); 1609 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d, 1610 desired_capacity_upper_bound); 1611 1612 // We can now safely turn them into size_t's. 1613 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d; 1614 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d; 1615 1616 // This assert only makes sense here, before we adjust them 1617 // with respect to the min and max heap size. 1618 assert(minimum_desired_capacity <= maximum_desired_capacity, 1619 err_msg("minimum_desired_capacity = "SIZE_FORMAT", " 1620 "maximum_desired_capacity = "SIZE_FORMAT, 1621 minimum_desired_capacity, maximum_desired_capacity)); 1622 1623 // Should not be greater than the heap max size. No need to adjust 1624 // it with respect to the heap min size as it's a lower bound (i.e., 1625 // we'll try to make the capacity larger than it, not smaller). 1626 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size); 1627 // Should not be less than the heap min size. No need to adjust it 1628 // with respect to the heap max size as it's an upper bound (i.e., 1629 // we'll try to make the capacity smaller than it, not greater). 1630 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size); 1631 1632 if (capacity_after_gc < minimum_desired_capacity) { 1633 // Don't expand unless it's significant 1634 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc; 1635 ergo_verbose4(ErgoHeapSizing, 1636 "attempt heap expansion", 1637 ergo_format_reason("capacity lower than " 1638 "min desired capacity after Full GC") 1639 ergo_format_byte("capacity") 1640 ergo_format_byte("occupancy") 1641 ergo_format_byte_perc("min desired capacity"), 1642 capacity_after_gc, used_after_gc, 1643 minimum_desired_capacity, (double) MinHeapFreeRatio); 1644 expand(expand_bytes); 1645 1646 // No expansion, now see if we want to shrink 1647 } else if (capacity_after_gc > maximum_desired_capacity) { 1648 // Capacity too large, compute shrinking size 1649 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity; 1650 ergo_verbose4(ErgoHeapSizing, 1651 "attempt heap shrinking", 1652 ergo_format_reason("capacity higher than " 1653 "max desired capacity after Full GC") 1654 ergo_format_byte("capacity") 1655 ergo_format_byte("occupancy") 1656 ergo_format_byte_perc("max desired capacity"), 1657 capacity_after_gc, used_after_gc, 1658 maximum_desired_capacity, (double) MaxHeapFreeRatio); 1659 shrink(shrink_bytes); 1660 } 1661 } 1662 1663 1664 HeapWord* 1665 G1CollectedHeap::satisfy_failed_allocation(size_t word_size, 1666 bool* succeeded) { 1667 assert_at_safepoint(true /* should_be_vm_thread */); 1668 1669 *succeeded = true; 1670 // Let's attempt the allocation first. 1671 HeapWord* result = 1672 attempt_allocation_at_safepoint(word_size, 1673 false /* expect_null_mutator_alloc_region */); 1674 if (result != NULL) { 1675 assert(*succeeded, "sanity"); 1676 return result; 1677 } 1678 1679 // In a G1 heap, we're supposed to keep allocation from failing by 1680 // incremental pauses. Therefore, at least for now, we'll favor 1681 // expansion over collection. (This might change in the future if we can 1682 // do something smarter than full collection to satisfy a failed alloc.) 1683 result = expand_and_allocate(word_size); 1684 if (result != NULL) { 1685 assert(*succeeded, "sanity"); 1686 return result; 1687 } 1688 1689 // Expansion didn't work, we'll try to do a Full GC. 1690 bool gc_succeeded = do_collection(false, /* explicit_gc */ 1691 false, /* clear_all_soft_refs */ 1692 word_size); 1693 if (!gc_succeeded) { 1694 *succeeded = false; 1695 return NULL; 1696 } 1697 1698 // Retry the allocation 1699 result = attempt_allocation_at_safepoint(word_size, 1700 true /* expect_null_mutator_alloc_region */); 1701 if (result != NULL) { 1702 assert(*succeeded, "sanity"); 1703 return result; 1704 } 1705 1706 // Then, try a Full GC that will collect all soft references. 1707 gc_succeeded = do_collection(false, /* explicit_gc */ 1708 true, /* clear_all_soft_refs */ 1709 word_size); 1710 if (!gc_succeeded) { 1711 *succeeded = false; 1712 return NULL; 1713 } 1714 1715 // Retry the allocation once more 1716 result = attempt_allocation_at_safepoint(word_size, 1717 true /* expect_null_mutator_alloc_region */); 1718 if (result != NULL) { 1719 assert(*succeeded, "sanity"); 1720 return result; 1721 } 1722 1723 assert(!collector_policy()->should_clear_all_soft_refs(), 1724 "Flag should have been handled and cleared prior to this point"); 1725 1726 // What else? We might try synchronous finalization later. If the total 1727 // space available is large enough for the allocation, then a more 1728 // complete compaction phase than we've tried so far might be 1729 // appropriate. 1730 assert(*succeeded, "sanity"); 1731 return NULL; 1732 } 1733 1734 // Attempting to expand the heap sufficiently 1735 // to support an allocation of the given "word_size". If 1736 // successful, perform the allocation and return the address of the 1737 // allocated block, or else "NULL". 1738 1739 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) { 1740 assert_at_safepoint(true /* should_be_vm_thread */); 1741 1742 verify_region_sets_optional(); 1743 1744 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes); 1745 ergo_verbose1(ErgoHeapSizing, 1746 "attempt heap expansion", 1747 ergo_format_reason("allocation request failed") 1748 ergo_format_byte("allocation request"), 1749 word_size * HeapWordSize); 1750 if (expand(expand_bytes)) { 1751 _hrs.verify_optional(); 1752 verify_region_sets_optional(); 1753 return attempt_allocation_at_safepoint(word_size, 1754 false /* expect_null_mutator_alloc_region */); 1755 } 1756 return NULL; 1757 } 1758 1759 void G1CollectedHeap::update_committed_space(HeapWord* old_end, 1760 HeapWord* new_end) { 1761 assert(old_end != new_end, "don't call this otherwise"); 1762 assert((HeapWord*) _g1_storage.high() == new_end, "invariant"); 1763 1764 // Update the committed mem region. 1765 _g1_committed.set_end(new_end); 1766 // Tell the card table about the update. 1767 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed); 1768 // Tell the BOT about the update. 1769 _bot_shared->resize(_g1_committed.word_size()); 1770 } 1771 1772 bool G1CollectedHeap::expand(size_t expand_bytes) { 1773 size_t old_mem_size = _g1_storage.committed_size(); 1774 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); 1775 aligned_expand_bytes = align_size_up(aligned_expand_bytes, 1776 HeapRegion::GrainBytes); 1777 ergo_verbose2(ErgoHeapSizing, 1778 "expand the heap", 1779 ergo_format_byte("requested expansion amount") 1780 ergo_format_byte("attempted expansion amount"), 1781 expand_bytes, aligned_expand_bytes); 1782 1783 // First commit the memory. 1784 HeapWord* old_end = (HeapWord*) _g1_storage.high(); 1785 bool successful = _g1_storage.expand_by(aligned_expand_bytes); 1786 if (successful) { 1787 // Then propagate this update to the necessary data structures. 1788 HeapWord* new_end = (HeapWord*) _g1_storage.high(); 1789 update_committed_space(old_end, new_end); 1790 1791 FreeRegionList expansion_list("Local Expansion List"); 1792 MemRegion mr = _hrs.expand_by(old_end, new_end, &expansion_list); 1793 assert(mr.start() == old_end, "post-condition"); 1794 // mr might be a smaller region than what was requested if 1795 // expand_by() was unable to allocate the HeapRegion instances 1796 assert(mr.end() <= new_end, "post-condition"); 1797 1798 size_t actual_expand_bytes = mr.byte_size(); 1799 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition"); 1800 assert(actual_expand_bytes == expansion_list.total_capacity_bytes(), 1801 "post-condition"); 1802 if (actual_expand_bytes < aligned_expand_bytes) { 1803 // We could not expand _hrs to the desired size. In this case we 1804 // need to shrink the committed space accordingly. 1805 assert(mr.end() < new_end, "invariant"); 1806 1807 size_t diff_bytes = aligned_expand_bytes - actual_expand_bytes; 1808 // First uncommit the memory. 1809 _g1_storage.shrink_by(diff_bytes); 1810 // Then propagate this update to the necessary data structures. 1811 update_committed_space(new_end, mr.end()); 1812 } 1813 _free_list.add_as_tail(&expansion_list); 1814 1815 if (_hr_printer.is_active()) { 1816 HeapWord* curr = mr.start(); 1817 while (curr < mr.end()) { 1818 HeapWord* curr_end = curr + HeapRegion::GrainWords; 1819 _hr_printer.commit(curr, curr_end); 1820 curr = curr_end; 1821 } 1822 assert(curr == mr.end(), "post-condition"); 1823 } 1824 g1_policy()->record_new_heap_size(n_regions()); 1825 } else { 1826 ergo_verbose0(ErgoHeapSizing, 1827 "did not expand the heap", 1828 ergo_format_reason("heap expansion operation failed")); 1829 // The expansion of the virtual storage space was unsuccessful. 1830 // Let's see if it was because we ran out of swap. 1831 if (G1ExitOnExpansionFailure && 1832 _g1_storage.uncommitted_size() >= aligned_expand_bytes) { 1833 // We had head room... 1834 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion"); 1835 } 1836 } 1837 return successful; 1838 } 1839 1840 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) { 1841 size_t old_mem_size = _g1_storage.committed_size(); 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"), 1926 _secondary_free_list("Secondary Free List"), 1927 _old_set("Old Set"), 1928 _humongous_set("Master Humongous Set"), 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 _in_cset_fast_test(NULL), 1940 _in_cset_fast_test_base(NULL), 1941 _dirty_cards_region_list(NULL), 1942 _worker_cset_start_region(NULL), 1943 _worker_cset_start_region_time_stamp(NULL) { 1944 _g1h = this; // To catch bugs. 1945 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) { 1946 vm_exit_during_initialization("Failed necessary allocation."); 1947 } 1948 1949 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2; 1950 1951 int n_queues = MAX2((int)ParallelGCThreads, 1); 1952 _task_queues = new RefToScanQueueSet(n_queues); 1953 1954 int n_rem_sets = HeapRegionRemSet::num_par_rem_sets(); 1955 assert(n_rem_sets > 0, "Invariant."); 1956 1957 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC); 1958 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(unsigned int, n_queues, mtGC); 1959 1960 for (int i = 0; i < n_queues; i++) { 1961 RefToScanQueue* q = new RefToScanQueue(); 1962 q->initialize(); 1963 _task_queues->register_queue(i, q); 1964 } 1965 1966 clear_cset_start_regions(); 1967 1968 // Initialize the G1EvacuationFailureALot counters and flags. 1969 NOT_PRODUCT(reset_evacuation_should_fail();) 1970 1971 guarantee(_task_queues != NULL, "task_queues allocation failure."); 1972 } 1973 1974 jint G1CollectedHeap::initialize() { 1975 CollectedHeap::pre_initialize(); 1976 os::enable_vtime(); 1977 1978 G1Log::init(); 1979 1980 // Necessary to satisfy locking discipline assertions. 1981 1982 MutexLocker x(Heap_lock); 1983 1984 // We have to initialize the printer before committing the heap, as 1985 // it will be used then. 1986 _hr_printer.set_active(G1PrintHeapRegions); 1987 1988 // While there are no constraints in the GC code that HeapWordSize 1989 // be any particular value, there are multiple other areas in the 1990 // system which believe this to be true (e.g. oop->object_size in some 1991 // cases incorrectly returns the size in wordSize units rather than 1992 // HeapWordSize). 1993 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 1994 1995 size_t init_byte_size = collector_policy()->initial_heap_byte_size(); 1996 size_t max_byte_size = collector_policy()->max_heap_byte_size(); 1997 1998 // Ensure that the sizes are properly aligned. 1999 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap"); 2000 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap"); 2001 2002 _cg1r = new ConcurrentG1Refine(); 2003 2004 // Reserve the maximum. 2005 2006 // When compressed oops are enabled, the preferred heap base 2007 // is calculated by subtracting the requested size from the 2008 // 32Gb boundary and using the result as the base address for 2009 // heap reservation. If the requested size is not aligned to 2010 // HeapRegion::GrainBytes (i.e. the alignment that is passed 2011 // into the ReservedHeapSpace constructor) then the actual 2012 // base of the reserved heap may end up differing from the 2013 // address that was requested (i.e. the preferred heap base). 2014 // If this happens then we could end up using a non-optimal 2015 // compressed oops mode. 2016 2017 // Since max_byte_size is aligned to the size of a heap region (checked 2018 // above). 2019 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap"); 2020 2021 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size, 2022 HeapRegion::GrainBytes); 2023 2024 // It is important to do this in a way such that concurrent readers can't 2025 // temporarily think somethings in the heap. (I've actually seen this 2026 // happen in asserts: DLD.) 2027 _reserved.set_word_size(0); 2028 _reserved.set_start((HeapWord*)heap_rs.base()); 2029 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size())); 2030 2031 _expansion_regions = (uint) (max_byte_size / HeapRegion::GrainBytes); 2032 2033 // Create the gen rem set (and barrier set) for the entire reserved region. 2034 _rem_set = collector_policy()->create_rem_set(_reserved, 2); 2035 set_barrier_set(rem_set()->bs()); 2036 if (barrier_set()->is_a(BarrierSet::ModRef)) { 2037 _mr_bs = (ModRefBarrierSet*)_barrier_set; 2038 } else { 2039 vm_exit_during_initialization("G1 requires a mod ref bs."); 2040 return JNI_ENOMEM; 2041 } 2042 2043 // Also create a G1 rem set. 2044 if (mr_bs()->is_a(BarrierSet::CardTableModRef)) { 2045 _g1_rem_set = new G1RemSet(this, (CardTableModRefBS*)mr_bs()); 2046 } else { 2047 vm_exit_during_initialization("G1 requires a cardtable mod ref bs."); 2048 return JNI_ENOMEM; 2049 } 2050 2051 // Carve out the G1 part of the heap. 2052 2053 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size); 2054 _g1_reserved = MemRegion((HeapWord*)g1_rs.base(), 2055 g1_rs.size()/HeapWordSize); 2056 2057 _g1_storage.initialize(g1_rs, 0); 2058 _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0); 2059 _hrs.initialize((HeapWord*) _g1_reserved.start(), 2060 (HeapWord*) _g1_reserved.end(), 2061 _expansion_regions); 2062 2063 // 6843694 - ensure that the maximum region index can fit 2064 // in the remembered set structures. 2065 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; 2066 guarantee((max_regions() - 1) <= max_region_idx, "too many regions"); 2067 2068 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; 2069 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); 2070 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region, 2071 "too many cards per region"); 2072 2073 HeapRegionSet::set_unrealistically_long_length(max_regions() + 1); 2074 2075 _bot_shared = new G1BlockOffsetSharedArray(_reserved, 2076 heap_word_size(init_byte_size)); 2077 2078 _g1h = this; 2079 2080 _in_cset_fast_test_length = max_regions(); 2081 _in_cset_fast_test_base = 2082 NEW_C_HEAP_ARRAY(bool, (size_t) _in_cset_fast_test_length, mtGC); 2083 2084 // We're biasing _in_cset_fast_test to avoid subtracting the 2085 // beginning of the heap every time we want to index; basically 2086 // it's the same with what we do with the card table. 2087 _in_cset_fast_test = _in_cset_fast_test_base - 2088 ((uintx) _g1_reserved.start() >> HeapRegion::LogOfHRGrainBytes); 2089 2090 // Clear the _cset_fast_test bitmap in anticipation of adding 2091 // regions to the incremental collection set for the first 2092 // evacuation pause. 2093 clear_cset_fast_test(); 2094 2095 // Create the ConcurrentMark data structure and thread. 2096 // (Must do this late, so that "max_regions" is defined.) 2097 _cm = new ConcurrentMark(this, heap_rs); 2098 if (_cm == NULL || !_cm->completed_initialization()) { 2099 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark"); 2100 return JNI_ENOMEM; 2101 } 2102 _cmThread = _cm->cmThread(); 2103 2104 // Initialize the from_card cache structure of HeapRegionRemSet. 2105 HeapRegionRemSet::init_heap(max_regions()); 2106 2107 // Now expand into the initial heap size. 2108 if (!expand(init_byte_size)) { 2109 vm_shutdown_during_initialization("Failed to allocate initial heap."); 2110 return JNI_ENOMEM; 2111 } 2112 2113 // Perform any initialization actions delegated to the policy. 2114 g1_policy()->init(); 2115 2116 _refine_cte_cl = 2117 new RefineCardTableEntryClosure(ConcurrentG1RefineThread::sts(), 2118 g1_rem_set(), 2119 concurrent_g1_refine()); 2120 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl); 2121 2122 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon, 2123 SATB_Q_FL_lock, 2124 G1SATBProcessCompletedThreshold, 2125 Shared_SATB_Q_lock); 2126 2127 JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon, 2128 DirtyCardQ_FL_lock, 2129 concurrent_g1_refine()->yellow_zone(), 2130 concurrent_g1_refine()->red_zone(), 2131 Shared_DirtyCardQ_lock); 2132 2133 if (G1DeferredRSUpdate) { 2134 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon, 2135 DirtyCardQ_FL_lock, 2136 -1, // never trigger processing 2137 -1, // no limit on length 2138 Shared_DirtyCardQ_lock, 2139 &JavaThread::dirty_card_queue_set()); 2140 } 2141 2142 // Initialize the card queue set used to hold cards containing 2143 // references into the collection set. 2144 _into_cset_dirty_card_queue_set.initialize(DirtyCardQ_CBL_mon, 2145 DirtyCardQ_FL_lock, 2146 -1, // never trigger processing 2147 -1, // no limit on length 2148 Shared_DirtyCardQ_lock, 2149 &JavaThread::dirty_card_queue_set()); 2150 2151 // In case we're keeping closure specialization stats, initialize those 2152 // counts and that mechanism. 2153 SpecializationStats::clear(); 2154 2155 // Do later initialization work for concurrent refinement. 2156 _cg1r->init(); 2157 2158 // Here we allocate the dummy full region that is required by the 2159 // G1AllocRegion class. If we don't pass an address in the reserved 2160 // space here, lots of asserts fire. 2161 2162 HeapRegion* dummy_region = new_heap_region(0 /* index of bottom region */, 2163 _g1_reserved.start()); 2164 // We'll re-use the same region whether the alloc region will 2165 // require BOT updates or not and, if it doesn't, then a non-young 2166 // region will complain that it cannot support allocations without 2167 // BOT updates. So we'll tag the dummy region as young to avoid that. 2168 dummy_region->set_young(); 2169 // Make sure it's full. 2170 dummy_region->set_top(dummy_region->end()); 2171 G1AllocRegion::setup(this, dummy_region); 2172 2173 init_mutator_alloc_region(); 2174 2175 // Do create of the monitoring and management support so that 2176 // values in the heap have been properly initialized. 2177 _g1mm = new G1MonitoringSupport(this); 2178 2179 return JNI_OK; 2180 } 2181 2182 void G1CollectedHeap::ref_processing_init() { 2183 // Reference processing in G1 currently works as follows: 2184 // 2185 // * There are two reference processor instances. One is 2186 // used to record and process discovered references 2187 // during concurrent marking; the other is used to 2188 // record and process references during STW pauses 2189 // (both full and incremental). 2190 // * Both ref processors need to 'span' the entire heap as 2191 // the regions in the collection set may be dotted around. 2192 // 2193 // * For the concurrent marking ref processor: 2194 // * Reference discovery is enabled at initial marking. 2195 // * Reference discovery is disabled and the discovered 2196 // references processed etc during remarking. 2197 // * Reference discovery is MT (see below). 2198 // * Reference discovery requires a barrier (see below). 2199 // * Reference processing may or may not be MT 2200 // (depending on the value of ParallelRefProcEnabled 2201 // and ParallelGCThreads). 2202 // * A full GC disables reference discovery by the CM 2203 // ref processor and abandons any entries on it's 2204 // discovered lists. 2205 // 2206 // * For the STW processor: 2207 // * Non MT discovery is enabled at the start of a full GC. 2208 // * Processing and enqueueing during a full GC is non-MT. 2209 // * During a full GC, references are processed after marking. 2210 // 2211 // * Discovery (may or may not be MT) is enabled at the start 2212 // of an incremental evacuation pause. 2213 // * References are processed near the end of a STW evacuation pause. 2214 // * For both types of GC: 2215 // * Discovery is atomic - i.e. not concurrent. 2216 // * Reference discovery will not need a barrier. 2217 2218 SharedHeap::ref_processing_init(); 2219 MemRegion mr = reserved_region(); 2220 2221 // Concurrent Mark ref processor 2222 _ref_processor_cm = 2223 new ReferenceProcessor(mr, // span 2224 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2225 // mt processing 2226 (int) ParallelGCThreads, 2227 // degree of mt processing 2228 (ParallelGCThreads > 1) || (ConcGCThreads > 1), 2229 // mt discovery 2230 (int) MAX2(ParallelGCThreads, ConcGCThreads), 2231 // degree of mt discovery 2232 false, 2233 // Reference discovery is not atomic 2234 &_is_alive_closure_cm, 2235 // is alive closure 2236 // (for efficiency/performance) 2237 true); 2238 // Setting next fields of discovered 2239 // lists requires a barrier. 2240 2241 // STW ref processor 2242 _ref_processor_stw = 2243 new ReferenceProcessor(mr, // span 2244 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2245 // mt processing 2246 MAX2((int)ParallelGCThreads, 1), 2247 // degree of mt processing 2248 (ParallelGCThreads > 1), 2249 // mt discovery 2250 MAX2((int)ParallelGCThreads, 1), 2251 // degree of mt discovery 2252 true, 2253 // Reference discovery is atomic 2254 &_is_alive_closure_stw, 2255 // is alive closure 2256 // (for efficiency/performance) 2257 false); 2258 // Setting next fields of discovered 2259 // lists requires a barrier. 2260 } 2261 2262 size_t G1CollectedHeap::capacity() const { 2263 return _g1_committed.byte_size(); 2264 } 2265 2266 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) { 2267 assert(!hr->continuesHumongous(), "pre-condition"); 2268 hr->reset_gc_time_stamp(); 2269 if (hr->startsHumongous()) { 2270 uint first_index = hr->hrs_index() + 1; 2271 uint last_index = hr->last_hc_index(); 2272 for (uint i = first_index; i < last_index; i += 1) { 2273 HeapRegion* chr = region_at(i); 2274 assert(chr->continuesHumongous(), "sanity"); 2275 chr->reset_gc_time_stamp(); 2276 } 2277 } 2278 } 2279 2280 #ifndef PRODUCT 2281 class CheckGCTimeStampsHRClosure : public HeapRegionClosure { 2282 private: 2283 unsigned _gc_time_stamp; 2284 bool _failures; 2285 2286 public: 2287 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) : 2288 _gc_time_stamp(gc_time_stamp), _failures(false) { } 2289 2290 virtual bool doHeapRegion(HeapRegion* hr) { 2291 unsigned region_gc_time_stamp = hr->get_gc_time_stamp(); 2292 if (_gc_time_stamp != region_gc_time_stamp) { 2293 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, " 2294 "expected %d", HR_FORMAT_PARAMS(hr), 2295 region_gc_time_stamp, _gc_time_stamp); 2296 _failures = true; 2297 } 2298 return false; 2299 } 2300 2301 bool failures() { return _failures; } 2302 }; 2303 2304 void G1CollectedHeap::check_gc_time_stamps() { 2305 CheckGCTimeStampsHRClosure cl(_gc_time_stamp); 2306 heap_region_iterate(&cl); 2307 guarantee(!cl.failures(), "all GC time stamps should have been reset"); 2308 } 2309 #endif // PRODUCT 2310 2311 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, 2312 DirtyCardQueue* into_cset_dcq, 2313 bool concurrent, 2314 int worker_i) { 2315 // Clean cards in the hot card cache 2316 concurrent_g1_refine()->clean_up_cache(worker_i, g1_rem_set(), into_cset_dcq); 2317 2318 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 2319 int n_completed_buffers = 0; 2320 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) { 2321 n_completed_buffers++; 2322 } 2323 g1_policy()->phase_times()->record_update_rs_processed_buffers(worker_i, n_completed_buffers); 2324 dcqs.clear_n_completed_buffers(); 2325 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!"); 2326 } 2327 2328 2329 // Computes the sum of the storage used by the various regions. 2330 2331 size_t G1CollectedHeap::used() const { 2332 assert(Heap_lock->owner() != NULL, 2333 "Should be owned on this thread's behalf."); 2334 size_t result = _summary_bytes_used; 2335 // Read only once in case it is set to NULL concurrently 2336 HeapRegion* hr = _mutator_alloc_region.get(); 2337 if (hr != NULL) 2338 result += hr->used(); 2339 return result; 2340 } 2341 2342 size_t G1CollectedHeap::used_unlocked() const { 2343 size_t result = _summary_bytes_used; 2344 return result; 2345 } 2346 2347 class SumUsedClosure: public HeapRegionClosure { 2348 size_t _used; 2349 public: 2350 SumUsedClosure() : _used(0) {} 2351 bool doHeapRegion(HeapRegion* r) { 2352 if (!r->continuesHumongous()) { 2353 _used += r->used(); 2354 } 2355 return false; 2356 } 2357 size_t result() { return _used; } 2358 }; 2359 2360 size_t G1CollectedHeap::recalculate_used() const { 2361 SumUsedClosure blk; 2362 heap_region_iterate(&blk); 2363 return blk.result(); 2364 } 2365 2366 size_t G1CollectedHeap::unsafe_max_alloc() { 2367 if (free_regions() > 0) return HeapRegion::GrainBytes; 2368 // otherwise, is there space in the current allocation region? 2369 2370 // We need to store the current allocation region in a local variable 2371 // here. The problem is that this method doesn't take any locks and 2372 // there may be other threads which overwrite the current allocation 2373 // region field. attempt_allocation(), for example, sets it to NULL 2374 // and this can happen *after* the NULL check here but before the call 2375 // to free(), resulting in a SIGSEGV. Note that this doesn't appear 2376 // to be a problem in the optimized build, since the two loads of the 2377 // current allocation region field are optimized away. 2378 HeapRegion* hr = _mutator_alloc_region.get(); 2379 if (hr == NULL) { 2380 return 0; 2381 } 2382 return hr->free(); 2383 } 2384 2385 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 2386 switch (cause) { 2387 case GCCause::_gc_locker: return GCLockerInvokesConcurrent; 2388 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent; 2389 case GCCause::_g1_humongous_allocation: return true; 2390 default: return false; 2391 } 2392 } 2393 2394 #ifndef PRODUCT 2395 void G1CollectedHeap::allocate_dummy_regions() { 2396 // Let's fill up most of the region 2397 size_t word_size = HeapRegion::GrainWords - 1024; 2398 // And as a result the region we'll allocate will be humongous. 2399 guarantee(isHumongous(word_size), "sanity"); 2400 2401 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) { 2402 // Let's use the existing mechanism for the allocation 2403 HeapWord* dummy_obj = humongous_obj_allocate(word_size); 2404 if (dummy_obj != NULL) { 2405 MemRegion mr(dummy_obj, word_size); 2406 CollectedHeap::fill_with_object(mr); 2407 } else { 2408 // If we can't allocate once, we probably cannot allocate 2409 // again. Let's get out of the loop. 2410 break; 2411 } 2412 } 2413 } 2414 #endif // !PRODUCT 2415 2416 void G1CollectedHeap::increment_old_marking_cycles_started() { 2417 assert(_old_marking_cycles_started == _old_marking_cycles_completed || 2418 _old_marking_cycles_started == _old_marking_cycles_completed + 1, 2419 err_msg("Wrong marking cycle count (started: %d, completed: %d)", 2420 _old_marking_cycles_started, _old_marking_cycles_completed)); 2421 2422 _old_marking_cycles_started++; 2423 } 2424 2425 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) { 2426 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 2427 2428 // We assume that if concurrent == true, then the caller is a 2429 // concurrent thread that was joined the Suspendible Thread 2430 // Set. If there's ever a cheap way to check this, we should add an 2431 // assert here. 2432 2433 // Given that this method is called at the end of a Full GC or of a 2434 // concurrent cycle, and those can be nested (i.e., a Full GC can 2435 // interrupt a concurrent cycle), the number of full collections 2436 // completed should be either one (in the case where there was no 2437 // nesting) or two (when a Full GC interrupted a concurrent cycle) 2438 // behind the number of full collections started. 2439 2440 // This is the case for the inner caller, i.e. a Full GC. 2441 assert(concurrent || 2442 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || 2443 (_old_marking_cycles_started == _old_marking_cycles_completed + 2), 2444 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u " 2445 "is inconsistent with _old_marking_cycles_completed = %u", 2446 _old_marking_cycles_started, _old_marking_cycles_completed)); 2447 2448 // This is the case for the outer caller, i.e. the concurrent cycle. 2449 assert(!concurrent || 2450 (_old_marking_cycles_started == _old_marking_cycles_completed + 1), 2451 err_msg("for outer caller (concurrent cycle): " 2452 "_old_marking_cycles_started = %u " 2453 "is inconsistent with _old_marking_cycles_completed = %u", 2454 _old_marking_cycles_started, _old_marking_cycles_completed)); 2455 2456 _old_marking_cycles_completed += 1; 2457 2458 // We need to clear the "in_progress" flag in the CM thread before 2459 // we wake up any waiters (especially when ExplicitInvokesConcurrent 2460 // is set) so that if a waiter requests another System.gc() it doesn't 2461 // incorrectly see that a marking cyle is still in progress. 2462 if (concurrent) { 2463 _cmThread->clear_in_progress(); 2464 } 2465 2466 // This notify_all() will ensure that a thread that called 2467 // System.gc() with (with ExplicitGCInvokesConcurrent set or not) 2468 // and it's waiting for a full GC to finish will be woken up. It is 2469 // waiting in VM_G1IncCollectionPause::doit_epilogue(). 2470 FullGCCount_lock->notify_all(); 2471 } 2472 2473 void G1CollectedHeap::collect(GCCause::Cause cause) { 2474 assert_heap_not_locked(); 2475 2476 unsigned int gc_count_before; 2477 unsigned int old_marking_count_before; 2478 bool retry_gc; 2479 2480 do { 2481 retry_gc = false; 2482 2483 { 2484 MutexLocker ml(Heap_lock); 2485 2486 // Read the GC count while holding the Heap_lock 2487 gc_count_before = total_collections(); 2488 old_marking_count_before = _old_marking_cycles_started; 2489 } 2490 2491 if (should_do_concurrent_full_gc(cause)) { 2492 // Schedule an initial-mark evacuation pause that will start a 2493 // concurrent cycle. We're setting word_size to 0 which means that 2494 // we are not requesting a post-GC allocation. 2495 VM_G1IncCollectionPause op(gc_count_before, 2496 0, /* word_size */ 2497 true, /* should_initiate_conc_mark */ 2498 g1_policy()->max_pause_time_ms(), 2499 cause); 2500 2501 VMThread::execute(&op); 2502 if (!op.pause_succeeded()) { 2503 if (old_marking_count_before == _old_marking_cycles_started) { 2504 retry_gc = op.should_retry_gc(); 2505 } else { 2506 // A Full GC happened while we were trying to schedule the 2507 // initial-mark GC. No point in starting a new cycle given 2508 // that the whole heap was collected anyway. 2509 } 2510 2511 if (retry_gc) { 2512 if (GC_locker::is_active_and_needs_gc()) { 2513 GC_locker::stall_until_clear(); 2514 } 2515 } 2516 } 2517 } else { 2518 if (cause == GCCause::_gc_locker 2519 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { 2520 2521 // Schedule a standard evacuation pause. We're setting word_size 2522 // to 0 which means that we are not requesting a post-GC allocation. 2523 VM_G1IncCollectionPause op(gc_count_before, 2524 0, /* word_size */ 2525 false, /* should_initiate_conc_mark */ 2526 g1_policy()->max_pause_time_ms(), 2527 cause); 2528 VMThread::execute(&op); 2529 } else { 2530 // Schedule a Full GC. 2531 VM_G1CollectFull op(gc_count_before, old_marking_count_before, cause); 2532 VMThread::execute(&op); 2533 } 2534 } 2535 } while (retry_gc); 2536 } 2537 2538 bool G1CollectedHeap::is_in(const void* p) const { 2539 if (_g1_committed.contains(p)) { 2540 // Given that we know that p is in the committed space, 2541 // heap_region_containing_raw() should successfully 2542 // return the containing region. 2543 HeapRegion* hr = heap_region_containing_raw(p); 2544 return hr->is_in(p); 2545 } else { 2546 return false; 2547 } 2548 } 2549 2550 // Iteration functions. 2551 2552 // Iterates an OopClosure over all ref-containing fields of objects 2553 // within a HeapRegion. 2554 2555 class IterateOopClosureRegionClosure: public HeapRegionClosure { 2556 MemRegion _mr; 2557 ExtendedOopClosure* _cl; 2558 public: 2559 IterateOopClosureRegionClosure(MemRegion mr, ExtendedOopClosure* cl) 2560 : _mr(mr), _cl(cl) {} 2561 bool doHeapRegion(HeapRegion* r) { 2562 if (!r->continuesHumongous()) { 2563 r->oop_iterate(_cl); 2564 } 2565 return false; 2566 } 2567 }; 2568 2569 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) { 2570 IterateOopClosureRegionClosure blk(_g1_committed, cl); 2571 heap_region_iterate(&blk); 2572 } 2573 2574 void G1CollectedHeap::oop_iterate(MemRegion mr, ExtendedOopClosure* cl) { 2575 IterateOopClosureRegionClosure blk(mr, cl); 2576 heap_region_iterate(&blk); 2577 } 2578 2579 // Iterates an ObjectClosure over all objects within a HeapRegion. 2580 2581 class IterateObjectClosureRegionClosure: public HeapRegionClosure { 2582 ObjectClosure* _cl; 2583 public: 2584 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} 2585 bool doHeapRegion(HeapRegion* r) { 2586 if (! r->continuesHumongous()) { 2587 r->object_iterate(_cl); 2588 } 2589 return false; 2590 } 2591 }; 2592 2593 void G1CollectedHeap::object_iterate(ObjectClosure* cl) { 2594 IterateObjectClosureRegionClosure blk(cl); 2595 heap_region_iterate(&blk); 2596 } 2597 2598 void G1CollectedHeap::object_iterate_since_last_GC(ObjectClosure* cl) { 2599 // FIXME: is this right? 2600 guarantee(false, "object_iterate_since_last_GC not supported by G1 heap"); 2601 } 2602 2603 // Calls a SpaceClosure on a HeapRegion. 2604 2605 class SpaceClosureRegionClosure: public HeapRegionClosure { 2606 SpaceClosure* _cl; 2607 public: 2608 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {} 2609 bool doHeapRegion(HeapRegion* r) { 2610 _cl->do_space(r); 2611 return false; 2612 } 2613 }; 2614 2615 void G1CollectedHeap::space_iterate(SpaceClosure* cl) { 2616 SpaceClosureRegionClosure blk(cl); 2617 heap_region_iterate(&blk); 2618 } 2619 2620 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { 2621 _hrs.iterate(cl); 2622 } 2623 2624 void 2625 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl, 2626 uint worker_id, 2627 uint no_of_par_workers, 2628 jint claim_value) { 2629 const uint regions = n_regions(); 2630 const uint max_workers = (G1CollectedHeap::use_parallel_gc_threads() ? 2631 no_of_par_workers : 2632 1); 2633 assert(UseDynamicNumberOfGCThreads || 2634 no_of_par_workers == workers()->total_workers(), 2635 "Non dynamic should use fixed number of workers"); 2636 // try to spread out the starting points of the workers 2637 const HeapRegion* start_hr = 2638 start_region_for_worker(worker_id, no_of_par_workers); 2639 const uint start_index = start_hr->hrs_index(); 2640 2641 // each worker will actually look at all regions 2642 for (uint count = 0; count < regions; ++count) { 2643 const uint index = (start_index + count) % regions; 2644 assert(0 <= index && index < regions, "sanity"); 2645 HeapRegion* r = region_at(index); 2646 // we'll ignore "continues humongous" regions (we'll process them 2647 // when we come across their corresponding "start humongous" 2648 // region) and regions already claimed 2649 if (r->claim_value() == claim_value || r->continuesHumongous()) { 2650 continue; 2651 } 2652 // OK, try to claim it 2653 if (r->claimHeapRegion(claim_value)) { 2654 // success! 2655 assert(!r->continuesHumongous(), "sanity"); 2656 if (r->startsHumongous()) { 2657 // If the region is "starts humongous" we'll iterate over its 2658 // "continues humongous" first; in fact we'll do them 2659 // first. The order is important. In on case, calling the 2660 // closure on the "starts humongous" region might de-allocate 2661 // and clear all its "continues humongous" regions and, as a 2662 // result, we might end up processing them twice. So, we'll do 2663 // them first (notice: most closures will ignore them anyway) and 2664 // then we'll do the "starts humongous" region. 2665 for (uint ch_index = index + 1; ch_index < regions; ++ch_index) { 2666 HeapRegion* chr = region_at(ch_index); 2667 2668 // if the region has already been claimed or it's not 2669 // "continues humongous" we're done 2670 if (chr->claim_value() == claim_value || 2671 !chr->continuesHumongous()) { 2672 break; 2673 } 2674 2675 // Noone should have claimed it directly. We can given 2676 // that we claimed its "starts humongous" region. 2677 assert(chr->claim_value() != claim_value, "sanity"); 2678 assert(chr->humongous_start_region() == r, "sanity"); 2679 2680 if (chr->claimHeapRegion(claim_value)) { 2681 // we should always be able to claim it; noone else should 2682 // be trying to claim this region 2683 2684 bool res2 = cl->doHeapRegion(chr); 2685 assert(!res2, "Should not abort"); 2686 2687 // Right now, this holds (i.e., no closure that actually 2688 // does something with "continues humongous" regions 2689 // clears them). We might have to weaken it in the future, 2690 // but let's leave these two asserts here for extra safety. 2691 assert(chr->continuesHumongous(), "should still be the case"); 2692 assert(chr->humongous_start_region() == r, "sanity"); 2693 } else { 2694 guarantee(false, "we should not reach here"); 2695 } 2696 } 2697 } 2698 2699 assert(!r->continuesHumongous(), "sanity"); 2700 bool res = cl->doHeapRegion(r); 2701 assert(!res, "Should not abort"); 2702 } 2703 } 2704 } 2705 2706 class ResetClaimValuesClosure: public HeapRegionClosure { 2707 public: 2708 bool doHeapRegion(HeapRegion* r) { 2709 r->set_claim_value(HeapRegion::InitialClaimValue); 2710 return false; 2711 } 2712 }; 2713 2714 void G1CollectedHeap::reset_heap_region_claim_values() { 2715 ResetClaimValuesClosure blk; 2716 heap_region_iterate(&blk); 2717 } 2718 2719 void G1CollectedHeap::reset_cset_heap_region_claim_values() { 2720 ResetClaimValuesClosure blk; 2721 collection_set_iterate(&blk); 2722 } 2723 2724 #ifdef ASSERT 2725 // This checks whether all regions in the heap have the correct claim 2726 // value. I also piggy-backed on this a check to ensure that the 2727 // humongous_start_region() information on "continues humongous" 2728 // regions is correct. 2729 2730 class CheckClaimValuesClosure : public HeapRegionClosure { 2731 private: 2732 jint _claim_value; 2733 uint _failures; 2734 HeapRegion* _sh_region; 2735 2736 public: 2737 CheckClaimValuesClosure(jint claim_value) : 2738 _claim_value(claim_value), _failures(0), _sh_region(NULL) { } 2739 bool doHeapRegion(HeapRegion* r) { 2740 if (r->claim_value() != _claim_value) { 2741 gclog_or_tty->print_cr("Region " HR_FORMAT ", " 2742 "claim value = %d, should be %d", 2743 HR_FORMAT_PARAMS(r), 2744 r->claim_value(), _claim_value); 2745 ++_failures; 2746 } 2747 if (!r->isHumongous()) { 2748 _sh_region = NULL; 2749 } else if (r->startsHumongous()) { 2750 _sh_region = r; 2751 } else if (r->continuesHumongous()) { 2752 if (r->humongous_start_region() != _sh_region) { 2753 gclog_or_tty->print_cr("Region " HR_FORMAT ", " 2754 "HS = "PTR_FORMAT", should be "PTR_FORMAT, 2755 HR_FORMAT_PARAMS(r), 2756 r->humongous_start_region(), 2757 _sh_region); 2758 ++_failures; 2759 } 2760 } 2761 return false; 2762 } 2763 uint failures() { return _failures; } 2764 }; 2765 2766 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) { 2767 CheckClaimValuesClosure cl(claim_value); 2768 heap_region_iterate(&cl); 2769 return cl.failures() == 0; 2770 } 2771 2772 class CheckClaimValuesInCSetHRClosure: public HeapRegionClosure { 2773 private: 2774 jint _claim_value; 2775 uint _failures; 2776 2777 public: 2778 CheckClaimValuesInCSetHRClosure(jint claim_value) : 2779 _claim_value(claim_value), _failures(0) { } 2780 2781 uint failures() { return _failures; } 2782 2783 bool doHeapRegion(HeapRegion* hr) { 2784 assert(hr->in_collection_set(), "how?"); 2785 assert(!hr->isHumongous(), "H-region in CSet"); 2786 if (hr->claim_value() != _claim_value) { 2787 gclog_or_tty->print_cr("CSet Region " HR_FORMAT ", " 2788 "claim value = %d, should be %d", 2789 HR_FORMAT_PARAMS(hr), 2790 hr->claim_value(), _claim_value); 2791 _failures += 1; 2792 } 2793 return false; 2794 } 2795 }; 2796 2797 bool G1CollectedHeap::check_cset_heap_region_claim_values(jint claim_value) { 2798 CheckClaimValuesInCSetHRClosure cl(claim_value); 2799 collection_set_iterate(&cl); 2800 return cl.failures() == 0; 2801 } 2802 #endif // ASSERT 2803 2804 // Clear the cached CSet starting regions and (more importantly) 2805 // the time stamps. Called when we reset the GC time stamp. 2806 void G1CollectedHeap::clear_cset_start_regions() { 2807 assert(_worker_cset_start_region != NULL, "sanity"); 2808 assert(_worker_cset_start_region_time_stamp != NULL, "sanity"); 2809 2810 int n_queues = MAX2((int)ParallelGCThreads, 1); 2811 for (int i = 0; i < n_queues; i++) { 2812 _worker_cset_start_region[i] = NULL; 2813 _worker_cset_start_region_time_stamp[i] = 0; 2814 } 2815 } 2816 2817 // Given the id of a worker, obtain or calculate a suitable 2818 // starting region for iterating over the current collection set. 2819 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(int worker_i) { 2820 assert(get_gc_time_stamp() > 0, "should have been updated by now"); 2821 2822 HeapRegion* result = NULL; 2823 unsigned gc_time_stamp = get_gc_time_stamp(); 2824 2825 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) { 2826 // Cached starting region for current worker was set 2827 // during the current pause - so it's valid. 2828 // Note: the cached starting heap region may be NULL 2829 // (when the collection set is empty). 2830 result = _worker_cset_start_region[worker_i]; 2831 assert(result == NULL || result->in_collection_set(), "sanity"); 2832 return result; 2833 } 2834 2835 // The cached entry was not valid so let's calculate 2836 // a suitable starting heap region for this worker. 2837 2838 // We want the parallel threads to start their collection 2839 // set iteration at different collection set regions to 2840 // avoid contention. 2841 // If we have: 2842 // n collection set regions 2843 // p threads 2844 // Then thread t will start at region floor ((t * n) / p) 2845 2846 result = g1_policy()->collection_set(); 2847 if (G1CollectedHeap::use_parallel_gc_threads()) { 2848 uint cs_size = g1_policy()->cset_region_length(); 2849 uint active_workers = workers()->active_workers(); 2850 assert(UseDynamicNumberOfGCThreads || 2851 active_workers == workers()->total_workers(), 2852 "Unless dynamic should use total workers"); 2853 2854 uint end_ind = (cs_size * worker_i) / active_workers; 2855 uint start_ind = 0; 2856 2857 if (worker_i > 0 && 2858 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) { 2859 // Previous workers starting region is valid 2860 // so let's iterate from there 2861 start_ind = (cs_size * (worker_i - 1)) / active_workers; 2862 result = _worker_cset_start_region[worker_i - 1]; 2863 } 2864 2865 for (uint i = start_ind; i < end_ind; i++) { 2866 result = result->next_in_collection_set(); 2867 } 2868 } 2869 2870 // Note: the calculated starting heap region may be NULL 2871 // (when the collection set is empty). 2872 assert(result == NULL || result->in_collection_set(), "sanity"); 2873 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp, 2874 "should be updated only once per pause"); 2875 _worker_cset_start_region[worker_i] = result; 2876 OrderAccess::storestore(); 2877 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp; 2878 return result; 2879 } 2880 2881 HeapRegion* G1CollectedHeap::start_region_for_worker(uint worker_i, 2882 uint no_of_par_workers) { 2883 uint worker_num = 2884 G1CollectedHeap::use_parallel_gc_threads() ? no_of_par_workers : 1U; 2885 assert(UseDynamicNumberOfGCThreads || 2886 no_of_par_workers == workers()->total_workers(), 2887 "Non dynamic should use fixed number of workers"); 2888 const uint start_index = n_regions() * worker_i / worker_num; 2889 return region_at(start_index); 2890 } 2891 2892 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) { 2893 HeapRegion* r = g1_policy()->collection_set(); 2894 while (r != NULL) { 2895 HeapRegion* next = r->next_in_collection_set(); 2896 if (cl->doHeapRegion(r)) { 2897 cl->incomplete(); 2898 return; 2899 } 2900 r = next; 2901 } 2902 } 2903 2904 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r, 2905 HeapRegionClosure *cl) { 2906 if (r == NULL) { 2907 // The CSet is empty so there's nothing to do. 2908 return; 2909 } 2910 2911 assert(r->in_collection_set(), 2912 "Start region must be a member of the collection set."); 2913 HeapRegion* cur = r; 2914 while (cur != NULL) { 2915 HeapRegion* next = cur->next_in_collection_set(); 2916 if (cl->doHeapRegion(cur) && false) { 2917 cl->incomplete(); 2918 return; 2919 } 2920 cur = next; 2921 } 2922 cur = g1_policy()->collection_set(); 2923 while (cur != r) { 2924 HeapRegion* next = cur->next_in_collection_set(); 2925 if (cl->doHeapRegion(cur) && false) { 2926 cl->incomplete(); 2927 return; 2928 } 2929 cur = next; 2930 } 2931 } 2932 2933 CompactibleSpace* G1CollectedHeap::first_compactible_space() { 2934 return n_regions() > 0 ? region_at(0) : NULL; 2935 } 2936 2937 2938 Space* G1CollectedHeap::space_containing(const void* addr) const { 2939 Space* res = heap_region_containing(addr); 2940 return res; 2941 } 2942 2943 HeapWord* G1CollectedHeap::block_start(const void* addr) const { 2944 Space* sp = space_containing(addr); 2945 if (sp != NULL) { 2946 return sp->block_start(addr); 2947 } 2948 return NULL; 2949 } 2950 2951 size_t G1CollectedHeap::block_size(const HeapWord* addr) const { 2952 Space* sp = space_containing(addr); 2953 assert(sp != NULL, "block_size of address outside of heap"); 2954 return sp->block_size(addr); 2955 } 2956 2957 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { 2958 Space* sp = space_containing(addr); 2959 return sp->block_is_obj(addr); 2960 } 2961 2962 bool G1CollectedHeap::supports_tlab_allocation() const { 2963 return true; 2964 } 2965 2966 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { 2967 return HeapRegion::GrainBytes; 2968 } 2969 2970 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { 2971 // Return the remaining space in the cur alloc region, but not less than 2972 // the min TLAB size. 2973 2974 // Also, this value can be at most the humongous object threshold, 2975 // since we can't allow tlabs to grow big enough to accomodate 2976 // humongous objects. 2977 2978 HeapRegion* hr = _mutator_alloc_region.get(); 2979 size_t max_tlab_size = _humongous_object_threshold_in_words * wordSize; 2980 if (hr == NULL) { 2981 return max_tlab_size; 2982 } else { 2983 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab_size); 2984 } 2985 } 2986 2987 size_t G1CollectedHeap::max_capacity() const { 2988 return _g1_reserved.byte_size(); 2989 } 2990 2991 jlong G1CollectedHeap::millis_since_last_gc() { 2992 // assert(false, "NYI"); 2993 return 0; 2994 } 2995 2996 void G1CollectedHeap::prepare_for_verify() { 2997 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) { 2998 ensure_parsability(false); 2999 } 3000 g1_rem_set()->prepare_for_verify(); 3001 } 3002 3003 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr, 3004 VerifyOption vo) { 3005 switch (vo) { 3006 case VerifyOption_G1UsePrevMarking: 3007 return hr->obj_allocated_since_prev_marking(obj); 3008 case VerifyOption_G1UseNextMarking: 3009 return hr->obj_allocated_since_next_marking(obj); 3010 case VerifyOption_G1UseMarkWord: 3011 return false; 3012 default: 3013 ShouldNotReachHere(); 3014 } 3015 return false; // keep some compilers happy 3016 } 3017 3018 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) { 3019 switch (vo) { 3020 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start(); 3021 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start(); 3022 case VerifyOption_G1UseMarkWord: return NULL; 3023 default: ShouldNotReachHere(); 3024 } 3025 return NULL; // keep some compilers happy 3026 } 3027 3028 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) { 3029 switch (vo) { 3030 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj); 3031 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj); 3032 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked(); 3033 default: ShouldNotReachHere(); 3034 } 3035 return false; // keep some compilers happy 3036 } 3037 3038 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) { 3039 switch (vo) { 3040 case VerifyOption_G1UsePrevMarking: return "PTAMS"; 3041 case VerifyOption_G1UseNextMarking: return "NTAMS"; 3042 case VerifyOption_G1UseMarkWord: return "NONE"; 3043 default: ShouldNotReachHere(); 3044 } 3045 return NULL; // keep some compilers happy 3046 } 3047 3048 class VerifyLivenessOopClosure: public OopClosure { 3049 G1CollectedHeap* _g1h; 3050 VerifyOption _vo; 3051 public: 3052 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo): 3053 _g1h(g1h), _vo(vo) 3054 { } 3055 void do_oop(narrowOop *p) { do_oop_work(p); } 3056 void do_oop( oop *p) { do_oop_work(p); } 3057 3058 template <class T> void do_oop_work(T *p) { 3059 oop obj = oopDesc::load_decode_heap_oop(p); 3060 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo), 3061 "Dead object referenced by a not dead object"); 3062 } 3063 }; 3064 3065 class VerifyObjsInRegionClosure: public ObjectClosure { 3066 private: 3067 G1CollectedHeap* _g1h; 3068 size_t _live_bytes; 3069 HeapRegion *_hr; 3070 VerifyOption _vo; 3071 public: 3072 // _vo == UsePrevMarking -> use "prev" marking information, 3073 // _vo == UseNextMarking -> use "next" marking information, 3074 // _vo == UseMarkWord -> use mark word from object header. 3075 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo) 3076 : _live_bytes(0), _hr(hr), _vo(vo) { 3077 _g1h = G1CollectedHeap::heap(); 3078 } 3079 void do_object(oop o) { 3080 VerifyLivenessOopClosure isLive(_g1h, _vo); 3081 assert(o != NULL, "Huh?"); 3082 if (!_g1h->is_obj_dead_cond(o, _vo)) { 3083 // If the object is alive according to the mark word, 3084 // then verify that the marking information agrees. 3085 // Note we can't verify the contra-positive of the 3086 // above: if the object is dead (according to the mark 3087 // word), it may not be marked, or may have been marked 3088 // but has since became dead, or may have been allocated 3089 // since the last marking. 3090 if (_vo == VerifyOption_G1UseMarkWord) { 3091 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch"); 3092 } 3093 3094 o->oop_iterate_no_header(&isLive); 3095 if (!_hr->obj_allocated_since_prev_marking(o)) { 3096 size_t obj_size = o->size(); // Make sure we don't overflow 3097 _live_bytes += (obj_size * HeapWordSize); 3098 } 3099 } 3100 } 3101 size_t live_bytes() { return _live_bytes; } 3102 }; 3103 3104 class PrintObjsInRegionClosure : public ObjectClosure { 3105 HeapRegion *_hr; 3106 G1CollectedHeap *_g1; 3107 public: 3108 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) { 3109 _g1 = G1CollectedHeap::heap(); 3110 }; 3111 3112 void do_object(oop o) { 3113 if (o != NULL) { 3114 HeapWord *start = (HeapWord *) o; 3115 size_t word_sz = o->size(); 3116 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT 3117 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n", 3118 (void*) o, word_sz, 3119 _g1->isMarkedPrev(o), 3120 _g1->isMarkedNext(o), 3121 _hr->obj_allocated_since_prev_marking(o)); 3122 HeapWord *end = start + word_sz; 3123 HeapWord *cur; 3124 int *val; 3125 for (cur = start; cur < end; cur++) { 3126 val = (int *) cur; 3127 gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val); 3128 } 3129 } 3130 } 3131 }; 3132 3133 class VerifyRegionClosure: public HeapRegionClosure { 3134 private: 3135 bool _par; 3136 VerifyOption _vo; 3137 bool _failures; 3138 public: 3139 // _vo == UsePrevMarking -> use "prev" marking information, 3140 // _vo == UseNextMarking -> use "next" marking information, 3141 // _vo == UseMarkWord -> use mark word from object header. 3142 VerifyRegionClosure(bool par, VerifyOption vo) 3143 : _par(par), 3144 _vo(vo), 3145 _failures(false) {} 3146 3147 bool failures() { 3148 return _failures; 3149 } 3150 3151 bool doHeapRegion(HeapRegion* r) { 3152 if (!r->continuesHumongous()) { 3153 bool failures = false; 3154 r->verify(_vo, &failures); 3155 if (failures) { 3156 _failures = true; 3157 } else { 3158 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo); 3159 r->object_iterate(¬_dead_yet_cl); 3160 if (_vo != VerifyOption_G1UseNextMarking) { 3161 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) { 3162 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] " 3163 "max_live_bytes "SIZE_FORMAT" " 3164 "< calculated "SIZE_FORMAT, 3165 r->bottom(), r->end(), 3166 r->max_live_bytes(), 3167 not_dead_yet_cl.live_bytes()); 3168 _failures = true; 3169 } 3170 } else { 3171 // When vo == UseNextMarking we cannot currently do a sanity 3172 // check on the live bytes as the calculation has not been 3173 // finalized yet. 3174 } 3175 } 3176 } 3177 return false; // stop the region iteration if we hit a failure 3178 } 3179 }; 3180 3181 class YoungRefCounterClosure : public OopClosure { 3182 G1CollectedHeap* _g1h; 3183 int _count; 3184 public: 3185 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {} 3186 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } } 3187 void do_oop(narrowOop* p) { ShouldNotReachHere(); } 3188 3189 int count() { return _count; } 3190 void reset_count() { _count = 0; }; 3191 }; 3192 3193 class VerifyKlassClosure: public KlassClosure { 3194 YoungRefCounterClosure _young_ref_counter_closure; 3195 OopClosure *_oop_closure; 3196 public: 3197 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {} 3198 void do_klass(Klass* k) { 3199 k->oops_do(_oop_closure); 3200 3201 _young_ref_counter_closure.reset_count(); 3202 k->oops_do(&_young_ref_counter_closure); 3203 if (_young_ref_counter_closure.count() > 0) { 3204 guarantee(k->has_modified_oops(), err_msg("Klass %p, has young refs but is not dirty.", k)); 3205 } 3206 } 3207 }; 3208 3209 // TODO: VerifyRootsClosure extends OopsInGenClosure so that we can 3210 // pass it as the perm_blk to SharedHeap::process_strong_roots. 3211 // When process_strong_roots stop calling perm_blk->younger_refs_iterate 3212 // we can change this closure to extend the simpler OopClosure. 3213 class VerifyRootsClosure: public OopsInGenClosure { 3214 private: 3215 G1CollectedHeap* _g1h; 3216 VerifyOption _vo; 3217 bool _failures; 3218 public: 3219 // _vo == UsePrevMarking -> use "prev" marking information, 3220 // _vo == UseNextMarking -> use "next" marking information, 3221 // _vo == UseMarkWord -> use mark word from object header. 3222 VerifyRootsClosure(VerifyOption vo) : 3223 _g1h(G1CollectedHeap::heap()), 3224 _vo(vo), 3225 _failures(false) { } 3226 3227 bool failures() { return _failures; } 3228 3229 template <class T> void do_oop_nv(T* p) { 3230 T heap_oop = oopDesc::load_heap_oop(p); 3231 if (!oopDesc::is_null(heap_oop)) { 3232 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 3233 if (_g1h->is_obj_dead_cond(obj, _vo)) { 3234 gclog_or_tty->print_cr("Root location "PTR_FORMAT" " 3235 "points to dead obj "PTR_FORMAT, p, (void*) obj); 3236 if (_vo == VerifyOption_G1UseMarkWord) { 3237 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark())); 3238 } 3239 obj->print_on(gclog_or_tty); 3240 _failures = true; 3241 } 3242 } 3243 } 3244 3245 void do_oop(oop* p) { do_oop_nv(p); } 3246 void do_oop(narrowOop* p) { do_oop_nv(p); } 3247 }; 3248 3249 // This is the task used for parallel heap verification. 3250 3251 class G1ParVerifyTask: public AbstractGangTask { 3252 private: 3253 G1CollectedHeap* _g1h; 3254 VerifyOption _vo; 3255 bool _failures; 3256 3257 public: 3258 // _vo == UsePrevMarking -> use "prev" marking information, 3259 // _vo == UseNextMarking -> use "next" marking information, 3260 // _vo == UseMarkWord -> use mark word from object header. 3261 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) : 3262 AbstractGangTask("Parallel verify task"), 3263 _g1h(g1h), 3264 _vo(vo), 3265 _failures(false) { } 3266 3267 bool failures() { 3268 return _failures; 3269 } 3270 3271 void work(uint worker_id) { 3272 HandleMark hm; 3273 VerifyRegionClosure blk(true, _vo); 3274 _g1h->heap_region_par_iterate_chunked(&blk, worker_id, 3275 _g1h->workers()->active_workers(), 3276 HeapRegion::ParVerifyClaimValue); 3277 if (blk.failures()) { 3278 _failures = true; 3279 } 3280 } 3281 }; 3282 3283 void G1CollectedHeap::verify(bool silent) { 3284 verify(silent, VerifyOption_G1UsePrevMarking); 3285 } 3286 3287 void G1CollectedHeap::verify(bool silent, 3288 VerifyOption vo) { 3289 if (SafepointSynchronize::is_at_safepoint()) { 3290 if (!silent) { gclog_or_tty->print("Roots "); } 3291 VerifyRootsClosure rootsCl(vo); 3292 3293 assert(Thread::current()->is_VM_thread(), 3294 "Expected to be executed serially by the VM thread at this point"); 3295 3296 CodeBlobToOopClosure blobsCl(&rootsCl, /*do_marking=*/ false); 3297 VerifyKlassClosure klassCl(this, &rootsCl); 3298 3299 // We apply the relevant closures to all the oops in the 3300 // system dictionary, the string table and the code cache. 3301 const int so = SO_AllClasses | SO_Strings | SO_CodeCache; 3302 3303 // Need cleared claim bits for the strong roots processing 3304 ClassLoaderDataGraph::clear_claimed_marks(); 3305 3306 process_strong_roots(true, // activate StrongRootsScope 3307 false, // we set "is scavenging" to false, 3308 // so we don't reset the dirty cards. 3309 ScanningOption(so), // roots scanning options 3310 &rootsCl, 3311 &blobsCl, 3312 &klassCl 3313 ); 3314 3315 bool failures = rootsCl.failures(); 3316 3317 if (vo != VerifyOption_G1UseMarkWord) { 3318 // If we're verifying during a full GC then the region sets 3319 // will have been torn down at the start of the GC. Therefore 3320 // verifying the region sets will fail. So we only verify 3321 // the region sets when not in a full GC. 3322 if (!silent) { gclog_or_tty->print("HeapRegionSets "); } 3323 verify_region_sets(); 3324 } 3325 3326 if (!silent) { gclog_or_tty->print("HeapRegions "); } 3327 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) { 3328 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue), 3329 "sanity check"); 3330 3331 G1ParVerifyTask task(this, vo); 3332 assert(UseDynamicNumberOfGCThreads || 3333 workers()->active_workers() == workers()->total_workers(), 3334 "If not dynamic should be using all the workers"); 3335 int n_workers = workers()->active_workers(); 3336 set_par_threads(n_workers); 3337 workers()->run_task(&task); 3338 set_par_threads(0); 3339 if (task.failures()) { 3340 failures = true; 3341 } 3342 3343 // Checks that the expected amount of parallel work was done. 3344 // The implication is that n_workers is > 0. 3345 assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue), 3346 "sanity check"); 3347 3348 reset_heap_region_claim_values(); 3349 3350 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue), 3351 "sanity check"); 3352 } else { 3353 VerifyRegionClosure blk(false, vo); 3354 heap_region_iterate(&blk); 3355 if (blk.failures()) { 3356 failures = true; 3357 } 3358 } 3359 if (!silent) gclog_or_tty->print("RemSet "); 3360 rem_set()->verify(); 3361 3362 if (failures) { 3363 gclog_or_tty->print_cr("Heap:"); 3364 // It helps to have the per-region information in the output to 3365 // help us track down what went wrong. This is why we call 3366 // print_extended_on() instead of print_on(). 3367 print_extended_on(gclog_or_tty); 3368 gclog_or_tty->print_cr(""); 3369 #ifndef PRODUCT 3370 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) { 3371 concurrent_mark()->print_reachable("at-verification-failure", 3372 vo, false /* all */); 3373 } 3374 #endif 3375 gclog_or_tty->flush(); 3376 } 3377 guarantee(!failures, "there should not have been any failures"); 3378 } else { 3379 if (!silent) 3380 gclog_or_tty->print("(SKIPPING roots, heapRegionSets, heapRegions, remset) "); 3381 } 3382 } 3383 3384 class PrintRegionClosure: public HeapRegionClosure { 3385 outputStream* _st; 3386 public: 3387 PrintRegionClosure(outputStream* st) : _st(st) {} 3388 bool doHeapRegion(HeapRegion* r) { 3389 r->print_on(_st); 3390 return false; 3391 } 3392 }; 3393 3394 void G1CollectedHeap::print_on(outputStream* st) const { 3395 st->print(" %-20s", "garbage-first heap"); 3396 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 3397 capacity()/K, used_unlocked()/K); 3398 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")", 3399 _g1_storage.low_boundary(), 3400 _g1_storage.high(), 3401 _g1_storage.high_boundary()); 3402 st->cr(); 3403 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); 3404 uint young_regions = _young_list->length(); 3405 st->print("%u young (" SIZE_FORMAT "K), ", young_regions, 3406 (size_t) young_regions * HeapRegion::GrainBytes / K); 3407 uint survivor_regions = g1_policy()->recorded_survivor_regions(); 3408 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, 3409 (size_t) survivor_regions * HeapRegion::GrainBytes / K); 3410 st->cr(); 3411 MetaspaceAux::print_on(st); 3412 } 3413 3414 void G1CollectedHeap::print_extended_on(outputStream* st) const { 3415 print_on(st); 3416 3417 // Print the per-region information. 3418 st->cr(); 3419 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), " 3420 "HS=humongous(starts), HC=humongous(continues), " 3421 "CS=collection set, F=free, TS=gc time stamp, " 3422 "PTAMS=previous top-at-mark-start, " 3423 "NTAMS=next top-at-mark-start)"); 3424 PrintRegionClosure blk(st); 3425 heap_region_iterate(&blk); 3426 } 3427 3428 void G1CollectedHeap::print_on_error(outputStream* st) const { 3429 this->CollectedHeap::print_on_error(st); 3430 3431 if (_cm != NULL) { 3432 st->cr(); 3433 _cm->print_on_error(st); 3434 } 3435 } 3436 3437 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const { 3438 if (G1CollectedHeap::use_parallel_gc_threads()) { 3439 workers()->print_worker_threads_on(st); 3440 } 3441 _cmThread->print_on(st); 3442 st->cr(); 3443 _cm->print_worker_threads_on(st); 3444 _cg1r->print_worker_threads_on(st); 3445 } 3446 3447 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { 3448 if (G1CollectedHeap::use_parallel_gc_threads()) { 3449 workers()->threads_do(tc); 3450 } 3451 tc->do_thread(_cmThread); 3452 _cg1r->threads_do(tc); 3453 } 3454 3455 void G1CollectedHeap::print_tracing_info() const { 3456 // We'll overload this to mean "trace GC pause statistics." 3457 if (TraceGen0Time || TraceGen1Time) { 3458 // The "G1CollectorPolicy" is keeping track of these stats, so delegate 3459 // to that. 3460 g1_policy()->print_tracing_info(); 3461 } 3462 if (G1SummarizeRSetStats) { 3463 g1_rem_set()->print_summary_info(); 3464 } 3465 if (G1SummarizeConcMark) { 3466 concurrent_mark()->print_summary_info(); 3467 } 3468 g1_policy()->print_yg_surv_rate_info(); 3469 SpecializationStats::print(); 3470 } 3471 3472 #ifndef PRODUCT 3473 // Helpful for debugging RSet issues. 3474 3475 class PrintRSetsClosure : public HeapRegionClosure { 3476 private: 3477 const char* _msg; 3478 size_t _occupied_sum; 3479 3480 public: 3481 bool doHeapRegion(HeapRegion* r) { 3482 HeapRegionRemSet* hrrs = r->rem_set(); 3483 size_t occupied = hrrs->occupied(); 3484 _occupied_sum += occupied; 3485 3486 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT, 3487 HR_FORMAT_PARAMS(r)); 3488 if (occupied == 0) { 3489 gclog_or_tty->print_cr(" RSet is empty"); 3490 } else { 3491 hrrs->print(); 3492 } 3493 gclog_or_tty->print_cr("----------"); 3494 return false; 3495 } 3496 3497 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { 3498 gclog_or_tty->cr(); 3499 gclog_or_tty->print_cr("========================================"); 3500 gclog_or_tty->print_cr(msg); 3501 gclog_or_tty->cr(); 3502 } 3503 3504 ~PrintRSetsClosure() { 3505 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum); 3506 gclog_or_tty->print_cr("========================================"); 3507 gclog_or_tty->cr(); 3508 } 3509 }; 3510 3511 void G1CollectedHeap::print_cset_rsets() { 3512 PrintRSetsClosure cl("Printing CSet RSets"); 3513 collection_set_iterate(&cl); 3514 } 3515 3516 void G1CollectedHeap::print_all_rsets() { 3517 PrintRSetsClosure cl("Printing All RSets");; 3518 heap_region_iterate(&cl); 3519 } 3520 #endif // PRODUCT 3521 3522 G1CollectedHeap* G1CollectedHeap::heap() { 3523 assert(_sh->kind() == CollectedHeap::G1CollectedHeap, 3524 "not a garbage-first heap"); 3525 return _g1h; 3526 } 3527 3528 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) { 3529 // always_do_update_barrier = false; 3530 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 3531 // Call allocation profiler 3532 AllocationProfiler::iterate_since_last_gc(); 3533 // Fill TLAB's and such 3534 ensure_parsability(true); 3535 } 3536 3537 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) { 3538 // FIXME: what is this about? 3539 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" 3540 // is set. 3541 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(), 3542 "derived pointer present")); 3543 // always_do_update_barrier = true; 3544 3545 // We have just completed a GC. Update the soft reference 3546 // policy with the new heap occupancy 3547 Universe::update_heap_info_at_gc(); 3548 } 3549 3550 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, 3551 unsigned int gc_count_before, 3552 bool* succeeded) { 3553 assert_heap_not_locked_and_not_at_safepoint(); 3554 g1_policy()->record_stop_world_start(); 3555 VM_G1IncCollectionPause op(gc_count_before, 3556 word_size, 3557 false, /* should_initiate_conc_mark */ 3558 g1_policy()->max_pause_time_ms(), 3559 GCCause::_g1_inc_collection_pause); 3560 VMThread::execute(&op); 3561 3562 HeapWord* result = op.result(); 3563 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded(); 3564 assert(result == NULL || ret_succeeded, 3565 "the result should be NULL if the VM did not succeed"); 3566 *succeeded = ret_succeeded; 3567 3568 assert_heap_not_locked(); 3569 return result; 3570 } 3571 3572 void 3573 G1CollectedHeap::doConcurrentMark() { 3574 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); 3575 if (!_cmThread->in_progress()) { 3576 _cmThread->set_started(); 3577 CGC_lock->notify(); 3578 } 3579 } 3580 3581 size_t G1CollectedHeap::pending_card_num() { 3582 size_t extra_cards = 0; 3583 JavaThread *curr = Threads::first(); 3584 while (curr != NULL) { 3585 DirtyCardQueue& dcq = curr->dirty_card_queue(); 3586 extra_cards += dcq.size(); 3587 curr = curr->next(); 3588 } 3589 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 3590 size_t buffer_size = dcqs.buffer_size(); 3591 size_t buffer_num = dcqs.completed_buffers_num(); 3592 3593 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes 3594 // in bytes - not the number of 'entries'. We need to convert 3595 // into a number of cards. 3596 return (buffer_size * buffer_num + extra_cards) / oopSize; 3597 } 3598 3599 size_t G1CollectedHeap::cards_scanned() { 3600 return g1_rem_set()->cardsScanned(); 3601 } 3602 3603 void 3604 G1CollectedHeap::setup_surviving_young_words() { 3605 assert(_surviving_young_words == NULL, "pre-condition"); 3606 uint array_length = g1_policy()->young_cset_region_length(); 3607 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC); 3608 if (_surviving_young_words == NULL) { 3609 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR, 3610 "Not enough space for young surv words summary."); 3611 } 3612 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t)); 3613 #ifdef ASSERT 3614 for (uint i = 0; i < array_length; ++i) { 3615 assert( _surviving_young_words[i] == 0, "memset above" ); 3616 } 3617 #endif // !ASSERT 3618 } 3619 3620 void 3621 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) { 3622 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); 3623 uint array_length = g1_policy()->young_cset_region_length(); 3624 for (uint i = 0; i < array_length; ++i) { 3625 _surviving_young_words[i] += surv_young_words[i]; 3626 } 3627 } 3628 3629 void 3630 G1CollectedHeap::cleanup_surviving_young_words() { 3631 guarantee( _surviving_young_words != NULL, "pre-condition" ); 3632 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words, mtGC); 3633 _surviving_young_words = NULL; 3634 } 3635 3636 #ifdef ASSERT 3637 class VerifyCSetClosure: public HeapRegionClosure { 3638 public: 3639 bool doHeapRegion(HeapRegion* hr) { 3640 // Here we check that the CSet region's RSet is ready for parallel 3641 // iteration. The fields that we'll verify are only manipulated 3642 // when the region is part of a CSet and is collected. Afterwards, 3643 // we reset these fields when we clear the region's RSet (when the 3644 // region is freed) so they are ready when the region is 3645 // re-allocated. The only exception to this is if there's an 3646 // evacuation failure and instead of freeing the region we leave 3647 // it in the heap. In that case, we reset these fields during 3648 // evacuation failure handling. 3649 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification"); 3650 3651 // Here's a good place to add any other checks we'd like to 3652 // perform on CSet regions. 3653 return false; 3654 } 3655 }; 3656 #endif // ASSERT 3657 3658 #if TASKQUEUE_STATS 3659 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) { 3660 st->print_raw_cr("GC Task Stats"); 3661 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); 3662 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); 3663 } 3664 3665 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const { 3666 print_taskqueue_stats_hdr(st); 3667 3668 TaskQueueStats totals; 3669 const int n = workers() != NULL ? workers()->total_workers() : 1; 3670 for (int i = 0; i < n; ++i) { 3671 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr(); 3672 totals += task_queue(i)->stats; 3673 } 3674 st->print_raw("tot "); totals.print(st); st->cr(); 3675 3676 DEBUG_ONLY(totals.verify()); 3677 } 3678 3679 void G1CollectedHeap::reset_taskqueue_stats() { 3680 const int n = workers() != NULL ? workers()->total_workers() : 1; 3681 for (int i = 0; i < n; ++i) { 3682 task_queue(i)->stats.reset(); 3683 } 3684 } 3685 #endif // TASKQUEUE_STATS 3686 3687 void G1CollectedHeap::log_gc_header() { 3688 if (!G1Log::fine()) { 3689 return; 3690 } 3691 3692 gclog_or_tty->date_stamp(PrintGCDateStamps); 3693 gclog_or_tty->stamp(PrintGCTimeStamps); 3694 3695 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause()) 3696 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)") 3697 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : ""); 3698 3699 gclog_or_tty->print("[%s", (const char*)gc_cause_str); 3700 } 3701 3702 void G1CollectedHeap::log_gc_footer(double pause_time_sec) { 3703 if (!G1Log::fine()) { 3704 return; 3705 } 3706 3707 if (G1Log::finer()) { 3708 if (evacuation_failed()) { 3709 gclog_or_tty->print(" (to-space exhausted)"); 3710 } 3711 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec); 3712 g1_policy()->phase_times()->note_gc_end(); 3713 g1_policy()->phase_times()->print(pause_time_sec); 3714 g1_policy()->print_detailed_heap_transition(); 3715 } else { 3716 if (evacuation_failed()) { 3717 gclog_or_tty->print("--"); 3718 } 3719 g1_policy()->print_heap_transition(); 3720 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec); 3721 } 3722 gclog_or_tty->flush(); 3723 } 3724 3725 bool 3726 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { 3727 assert_at_safepoint(true /* should_be_vm_thread */); 3728 guarantee(!is_gc_active(), "collection is not reentrant"); 3729 3730 if (GC_locker::check_active_before_gc()) { 3731 return false; 3732 } 3733 3734 SvcGCMarker sgcm(SvcGCMarker::MINOR); 3735 ResourceMark rm; 3736 3737 print_heap_before_gc(); 3738 3739 HRSPhaseSetter x(HRSPhaseEvacuation); 3740 verify_region_sets_optional(); 3741 verify_dirty_young_regions(); 3742 3743 // This call will decide whether this pause is an initial-mark 3744 // pause. If it is, during_initial_mark_pause() will return true 3745 // for the duration of this pause. 3746 g1_policy()->decide_on_conc_mark_initiation(); 3747 3748 // We do not allow initial-mark to be piggy-backed on a mixed GC. 3749 assert(!g1_policy()->during_initial_mark_pause() || 3750 g1_policy()->gcs_are_young(), "sanity"); 3751 3752 // We also do not allow mixed GCs during marking. 3753 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity"); 3754 3755 // Record whether this pause is an initial mark. When the current 3756 // thread has completed its logging output and it's safe to signal 3757 // the CM thread, the flag's value in the policy has been reset. 3758 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause(); 3759 3760 // Inner scope for scope based logging, timers, and stats collection 3761 { 3762 if (g1_policy()->during_initial_mark_pause()) { 3763 // We are about to start a marking cycle, so we increment the 3764 // full collection counter. 3765 increment_old_marking_cycles_started(); 3766 } 3767 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty); 3768 3769 int active_workers = (G1CollectedHeap::use_parallel_gc_threads() ? 3770 workers()->active_workers() : 1); 3771 double pause_start_sec = os::elapsedTime(); 3772 g1_policy()->phase_times()->note_gc_start(active_workers); 3773 log_gc_header(); 3774 3775 TraceCollectorStats tcs(g1mm()->incremental_collection_counters()); 3776 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause()); 3777 3778 // If the secondary_free_list is not empty, append it to the 3779 // free_list. No need to wait for the cleanup operation to finish; 3780 // the region allocation code will check the secondary_free_list 3781 // and wait if necessary. If the G1StressConcRegionFreeing flag is 3782 // set, skip this step so that the region allocation code has to 3783 // get entries from the secondary_free_list. 3784 if (!G1StressConcRegionFreeing) { 3785 append_secondary_free_list_if_not_empty_with_lock(); 3786 } 3787 3788 assert(check_young_list_well_formed(), 3789 "young list should be well formed"); 3790 3791 // Don't dynamically change the number of GC threads this early. A value of 3792 // 0 is used to indicate serial work. When parallel work is done, 3793 // it will be set. 3794 3795 { // Call to jvmpi::post_class_unload_events must occur outside of active GC 3796 IsGCActiveMark x; 3797 3798 gc_prologue(false); 3799 increment_total_collections(false /* full gc */); 3800 increment_gc_time_stamp(); 3801 3802 verify_before_gc(); 3803 3804 COMPILER2_PRESENT(DerivedPointerTable::clear()); 3805 3806 // Please see comment in g1CollectedHeap.hpp and 3807 // G1CollectedHeap::ref_processing_init() to see how 3808 // reference processing currently works in G1. 3809 3810 // Enable discovery in the STW reference processor 3811 ref_processor_stw()->enable_discovery(true /*verify_disabled*/, 3812 true /*verify_no_refs*/); 3813 3814 { 3815 // We want to temporarily turn off discovery by the 3816 // CM ref processor, if necessary, and turn it back on 3817 // on again later if we do. Using a scoped 3818 // NoRefDiscovery object will do this. 3819 NoRefDiscovery no_cm_discovery(ref_processor_cm()); 3820 3821 // Forget the current alloc region (we might even choose it to be part 3822 // of the collection set!). 3823 release_mutator_alloc_region(); 3824 3825 // We should call this after we retire the mutator alloc 3826 // region(s) so that all the ALLOC / RETIRE events are generated 3827 // before the start GC event. 3828 _hr_printer.start_gc(false /* full */, (size_t) total_collections()); 3829 3830 // This timing is only used by the ergonomics to handle our pause target. 3831 // It is unclear why this should not include the full pause. We will 3832 // investigate this in CR 7178365. 3833 // 3834 // Preserving the old comment here if that helps the investigation: 3835 // 3836 // The elapsed time induced by the start time below deliberately elides 3837 // the possible verification above. 3838 double sample_start_time_sec = os::elapsedTime(); 3839 3840 #if YOUNG_LIST_VERBOSE 3841 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:"); 3842 _young_list->print(); 3843 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 3844 #endif // YOUNG_LIST_VERBOSE 3845 3846 g1_policy()->record_collection_pause_start(sample_start_time_sec); 3847 3848 double scan_wait_start = os::elapsedTime(); 3849 // We have to wait until the CM threads finish scanning the 3850 // root regions as it's the only way to ensure that all the 3851 // objects on them have been correctly scanned before we start 3852 // moving them during the GC. 3853 bool waited = _cm->root_regions()->wait_until_scan_finished(); 3854 double wait_time_ms = 0.0; 3855 if (waited) { 3856 double scan_wait_end = os::elapsedTime(); 3857 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0; 3858 } 3859 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms); 3860 3861 #if YOUNG_LIST_VERBOSE 3862 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:"); 3863 _young_list->print(); 3864 #endif // YOUNG_LIST_VERBOSE 3865 3866 if (g1_policy()->during_initial_mark_pause()) { 3867 concurrent_mark()->checkpointRootsInitialPre(); 3868 } 3869 3870 #if YOUNG_LIST_VERBOSE 3871 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:"); 3872 _young_list->print(); 3873 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 3874 #endif // YOUNG_LIST_VERBOSE 3875 3876 g1_policy()->finalize_cset(target_pause_time_ms); 3877 3878 _cm->note_start_of_gc(); 3879 // We should not verify the per-thread SATB buffers given that 3880 // we have not filtered them yet (we'll do so during the 3881 // GC). We also call this after finalize_cset() to 3882 // ensure that the CSet has been finalized. 3883 _cm->verify_no_cset_oops(true /* verify_stacks */, 3884 true /* verify_enqueued_buffers */, 3885 false /* verify_thread_buffers */, 3886 true /* verify_fingers */); 3887 3888 if (_hr_printer.is_active()) { 3889 HeapRegion* hr = g1_policy()->collection_set(); 3890 while (hr != NULL) { 3891 G1HRPrinter::RegionType type; 3892 if (!hr->is_young()) { 3893 type = G1HRPrinter::Old; 3894 } else if (hr->is_survivor()) { 3895 type = G1HRPrinter::Survivor; 3896 } else { 3897 type = G1HRPrinter::Eden; 3898 } 3899 _hr_printer.cset(hr); 3900 hr = hr->next_in_collection_set(); 3901 } 3902 } 3903 3904 #ifdef ASSERT 3905 VerifyCSetClosure cl; 3906 collection_set_iterate(&cl); 3907 #endif // ASSERT 3908 3909 setup_surviving_young_words(); 3910 3911 // Initialize the GC alloc regions. 3912 init_gc_alloc_regions(); 3913 3914 // Actually do the work... 3915 evacuate_collection_set(); 3916 3917 // We do this to mainly verify the per-thread SATB buffers 3918 // (which have been filtered by now) since we didn't verify 3919 // them earlier. No point in re-checking the stacks / enqueued 3920 // buffers given that the CSet has not changed since last time 3921 // we checked. 3922 _cm->verify_no_cset_oops(false /* verify_stacks */, 3923 false /* verify_enqueued_buffers */, 3924 true /* verify_thread_buffers */, 3925 true /* verify_fingers */); 3926 3927 free_collection_set(g1_policy()->collection_set()); 3928 g1_policy()->clear_collection_set(); 3929 3930 cleanup_surviving_young_words(); 3931 3932 // Start a new incremental collection set for the next pause. 3933 g1_policy()->start_incremental_cset_building(); 3934 3935 // Clear the _cset_fast_test bitmap in anticipation of adding 3936 // regions to the incremental collection set for the next 3937 // evacuation pause. 3938 clear_cset_fast_test(); 3939 3940 _young_list->reset_sampled_info(); 3941 3942 // Don't check the whole heap at this point as the 3943 // GC alloc regions from this pause have been tagged 3944 // as survivors and moved on to the survivor list. 3945 // Survivor regions will fail the !is_young() check. 3946 assert(check_young_list_empty(false /* check_heap */), 3947 "young list should be empty"); 3948 3949 #if YOUNG_LIST_VERBOSE 3950 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:"); 3951 _young_list->print(); 3952 #endif // YOUNG_LIST_VERBOSE 3953 3954 g1_policy()->record_survivor_regions(_young_list->survivor_length(), 3955 _young_list->first_survivor_region(), 3956 _young_list->last_survivor_region()); 3957 3958 _young_list->reset_auxilary_lists(); 3959 3960 if (evacuation_failed()) { 3961 _summary_bytes_used = recalculate_used(); 3962 } else { 3963 // The "used" of the the collection set have already been subtracted 3964 // when they were freed. Add in the bytes evacuated. 3965 _summary_bytes_used += g1_policy()->bytes_copied_during_gc(); 3966 } 3967 3968 if (g1_policy()->during_initial_mark_pause()) { 3969 // We have to do this before we notify the CM threads that 3970 // they can start working to make sure that all the 3971 // appropriate initialization is done on the CM object. 3972 concurrent_mark()->checkpointRootsInitialPost(); 3973 set_marking_started(); 3974 // Note that we don't actually trigger the CM thread at 3975 // this point. We do that later when we're sure that 3976 // the current thread has completed its logging output. 3977 } 3978 3979 allocate_dummy_regions(); 3980 3981 #if YOUNG_LIST_VERBOSE 3982 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:"); 3983 _young_list->print(); 3984 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 3985 #endif // YOUNG_LIST_VERBOSE 3986 3987 init_mutator_alloc_region(); 3988 3989 { 3990 size_t expand_bytes = g1_policy()->expansion_amount(); 3991 if (expand_bytes > 0) { 3992 size_t bytes_before = capacity(); 3993 // No need for an ergo verbose message here, 3994 // expansion_amount() does this when it returns a value > 0. 3995 if (!expand(expand_bytes)) { 3996 // We failed to expand the heap so let's verify that 3997 // committed/uncommitted amount match the backing store 3998 assert(capacity() == _g1_storage.committed_size(), "committed size mismatch"); 3999 assert(max_capacity() == _g1_storage.reserved_size(), "reserved size mismatch"); 4000 } 4001 } 4002 } 4003 4004 // We redo the verificaiton but now wrt to the new CSet which 4005 // has just got initialized after the previous CSet was freed. 4006 _cm->verify_no_cset_oops(true /* verify_stacks */, 4007 true /* verify_enqueued_buffers */, 4008 true /* verify_thread_buffers */, 4009 true /* verify_fingers */); 4010 _cm->note_end_of_gc(); 4011 4012 // This timing is only used by the ergonomics to handle our pause target. 4013 // It is unclear why this should not include the full pause. We will 4014 // investigate this in CR 7178365. 4015 double sample_end_time_sec = os::elapsedTime(); 4016 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; 4017 g1_policy()->record_collection_pause_end(pause_time_ms); 4018 4019 MemoryService::track_memory_usage(); 4020 4021 // In prepare_for_verify() below we'll need to scan the deferred 4022 // update buffers to bring the RSets up-to-date if 4023 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning 4024 // the update buffers we'll probably need to scan cards on the 4025 // regions we just allocated to (i.e., the GC alloc 4026 // regions). However, during the last GC we called 4027 // set_saved_mark() on all the GC alloc regions, so card 4028 // scanning might skip the [saved_mark_word()...top()] area of 4029 // those regions (i.e., the area we allocated objects into 4030 // during the last GC). But it shouldn't. Given that 4031 // saved_mark_word() is conditional on whether the GC time stamp 4032 // on the region is current or not, by incrementing the GC time 4033 // stamp here we invalidate all the GC time stamps on all the 4034 // regions and saved_mark_word() will simply return top() for 4035 // all the regions. This is a nicer way of ensuring this rather 4036 // than iterating over the regions and fixing them. In fact, the 4037 // GC time stamp increment here also ensures that 4038 // saved_mark_word() will return top() between pauses, i.e., 4039 // during concurrent refinement. So we don't need the 4040 // is_gc_active() check to decided which top to use when 4041 // scanning cards (see CR 7039627). 4042 increment_gc_time_stamp(); 4043 4044 verify_after_gc(); 4045 4046 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 4047 ref_processor_stw()->verify_no_references_recorded(); 4048 4049 // CM reference discovery will be re-enabled if necessary. 4050 } 4051 4052 // We should do this after we potentially expand the heap so 4053 // that all the COMMIT events are generated before the end GC 4054 // event, and after we retire the GC alloc regions so that all 4055 // RETIRE events are generated before the end GC event. 4056 _hr_printer.end_gc(false /* full */, (size_t) total_collections()); 4057 4058 if (mark_in_progress()) { 4059 concurrent_mark()->update_g1_committed(); 4060 } 4061 4062 #ifdef TRACESPINNING 4063 ParallelTaskTerminator::print_termination_counts(); 4064 #endif 4065 4066 gc_epilogue(false); 4067 } 4068 4069 // Print the remainder of the GC log output. 4070 log_gc_footer(os::elapsedTime() - pause_start_sec); 4071 4072 // It is not yet to safe to tell the concurrent mark to 4073 // start as we have some optional output below. We don't want the 4074 // output from the concurrent mark thread interfering with this 4075 // logging output either. 4076 4077 _hrs.verify_optional(); 4078 verify_region_sets_optional(); 4079 4080 TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats()); 4081 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); 4082 4083 print_heap_after_gc(); 4084 4085 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 4086 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 4087 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 4088 // before any GC notifications are raised. 4089 g1mm()->update_sizes(); 4090 } 4091 4092 if (G1SummarizeRSetStats && 4093 (G1SummarizeRSetStatsPeriod > 0) && 4094 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) { 4095 g1_rem_set()->print_summary_info(); 4096 } 4097 4098 // It should now be safe to tell the concurrent mark thread to start 4099 // without its logging output interfering with the logging output 4100 // that came from the pause. 4101 4102 if (should_start_conc_mark) { 4103 // CAUTION: after the doConcurrentMark() call below, 4104 // the concurrent marking thread(s) could be running 4105 // concurrently with us. Make sure that anything after 4106 // this point does not assume that we are the only GC thread 4107 // running. Note: of course, the actual marking work will 4108 // not start until the safepoint itself is released in 4109 // ConcurrentGCThread::safepoint_desynchronize(). 4110 doConcurrentMark(); 4111 } 4112 4113 return true; 4114 } 4115 4116 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose) 4117 { 4118 size_t gclab_word_size; 4119 switch (purpose) { 4120 case GCAllocForSurvived: 4121 gclab_word_size = _survivor_plab_stats.desired_plab_sz(); 4122 break; 4123 case GCAllocForTenured: 4124 gclab_word_size = _old_plab_stats.desired_plab_sz(); 4125 break; 4126 default: 4127 assert(false, "unknown GCAllocPurpose"); 4128 gclab_word_size = _old_plab_stats.desired_plab_sz(); 4129 break; 4130 } 4131 4132 // Prevent humongous PLAB sizes for two reasons: 4133 // * PLABs are allocated using a similar paths as oops, but should 4134 // never be in a humongous region 4135 // * Allowing humongous PLABs needlessly churns the region free lists 4136 return MIN2(_humongous_object_threshold_in_words, gclab_word_size); 4137 } 4138 4139 void G1CollectedHeap::init_mutator_alloc_region() { 4140 assert(_mutator_alloc_region.get() == NULL, "pre-condition"); 4141 _mutator_alloc_region.init(); 4142 } 4143 4144 void G1CollectedHeap::release_mutator_alloc_region() { 4145 _mutator_alloc_region.release(); 4146 assert(_mutator_alloc_region.get() == NULL, "post-condition"); 4147 } 4148 4149 void G1CollectedHeap::init_gc_alloc_regions() { 4150 assert_at_safepoint(true /* should_be_vm_thread */); 4151 4152 _survivor_gc_alloc_region.init(); 4153 _old_gc_alloc_region.init(); 4154 HeapRegion* retained_region = _retained_old_gc_alloc_region; 4155 _retained_old_gc_alloc_region = NULL; 4156 4157 // We will discard the current GC alloc region if: 4158 // a) it's in the collection set (it can happen!), 4159 // b) it's already full (no point in using it), 4160 // c) it's empty (this means that it was emptied during 4161 // a cleanup and it should be on the free list now), or 4162 // d) it's humongous (this means that it was emptied 4163 // during a cleanup and was added to the free list, but 4164 // has been subseqently used to allocate a humongous 4165 // object that may be less than the region size). 4166 if (retained_region != NULL && 4167 !retained_region->in_collection_set() && 4168 !(retained_region->top() == retained_region->end()) && 4169 !retained_region->is_empty() && 4170 !retained_region->isHumongous()) { 4171 retained_region->set_saved_mark(); 4172 // The retained region was added to the old region set when it was 4173 // retired. We have to remove it now, since we don't allow regions 4174 // we allocate to in the region sets. We'll re-add it later, when 4175 // it's retired again. 4176 _old_set.remove(retained_region); 4177 bool during_im = g1_policy()->during_initial_mark_pause(); 4178 retained_region->note_start_of_copying(during_im); 4179 _old_gc_alloc_region.set(retained_region); 4180 _hr_printer.reuse(retained_region); 4181 } 4182 } 4183 4184 void G1CollectedHeap::release_gc_alloc_regions(uint no_of_gc_workers) { 4185 _survivor_gc_alloc_region.release(); 4186 // If we have an old GC alloc region to release, we'll save it in 4187 // _retained_old_gc_alloc_region. If we don't 4188 // _retained_old_gc_alloc_region will become NULL. This is what we 4189 // want either way so no reason to check explicitly for either 4190 // condition. 4191 _retained_old_gc_alloc_region = _old_gc_alloc_region.release(); 4192 4193 if (ResizePLAB) { 4194 _survivor_plab_stats.adjust_desired_plab_sz(no_of_gc_workers); 4195 _old_plab_stats.adjust_desired_plab_sz(no_of_gc_workers); 4196 } 4197 } 4198 4199 void G1CollectedHeap::abandon_gc_alloc_regions() { 4200 assert(_survivor_gc_alloc_region.get() == NULL, "pre-condition"); 4201 assert(_old_gc_alloc_region.get() == NULL, "pre-condition"); 4202 _retained_old_gc_alloc_region = NULL; 4203 } 4204 4205 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) { 4206 _drain_in_progress = false; 4207 set_evac_failure_closure(cl); 4208 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true); 4209 } 4210 4211 void G1CollectedHeap::finalize_for_evac_failure() { 4212 assert(_evac_failure_scan_stack != NULL && 4213 _evac_failure_scan_stack->length() == 0, 4214 "Postcondition"); 4215 assert(!_drain_in_progress, "Postcondition"); 4216 delete _evac_failure_scan_stack; 4217 _evac_failure_scan_stack = NULL; 4218 } 4219 4220 void G1CollectedHeap::remove_self_forwarding_pointers() { 4221 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity"); 4222 4223 G1ParRemoveSelfForwardPtrsTask rsfp_task(this); 4224 4225 if (G1CollectedHeap::use_parallel_gc_threads()) { 4226 set_par_threads(); 4227 workers()->run_task(&rsfp_task); 4228 set_par_threads(0); 4229 } else { 4230 rsfp_task.work(0); 4231 } 4232 4233 assert(check_cset_heap_region_claim_values(HeapRegion::ParEvacFailureClaimValue), "sanity"); 4234 4235 // Reset the claim values in the regions in the collection set. 4236 reset_cset_heap_region_claim_values(); 4237 4238 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity"); 4239 4240 // Now restore saved marks, if any. 4241 assert(_objs_with_preserved_marks.size() == 4242 _preserved_marks_of_objs.size(), "Both or none."); 4243 while (!_objs_with_preserved_marks.is_empty()) { 4244 oop obj = _objs_with_preserved_marks.pop(); 4245 markOop m = _preserved_marks_of_objs.pop(); 4246 obj->set_mark(m); 4247 } 4248 _objs_with_preserved_marks.clear(true); 4249 _preserved_marks_of_objs.clear(true); 4250 } 4251 4252 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) { 4253 _evac_failure_scan_stack->push(obj); 4254 } 4255 4256 void G1CollectedHeap::drain_evac_failure_scan_stack() { 4257 assert(_evac_failure_scan_stack != NULL, "precondition"); 4258 4259 while (_evac_failure_scan_stack->length() > 0) { 4260 oop obj = _evac_failure_scan_stack->pop(); 4261 _evac_failure_closure->set_region(heap_region_containing(obj)); 4262 obj->oop_iterate_backwards(_evac_failure_closure); 4263 } 4264 } 4265 4266 oop 4267 G1CollectedHeap::handle_evacuation_failure_par(OopsInHeapRegionClosure* cl, 4268 oop old) { 4269 assert(obj_in_cs(old), 4270 err_msg("obj: "PTR_FORMAT" should still be in the CSet", 4271 (HeapWord*) old)); 4272 markOop m = old->mark(); 4273 oop forward_ptr = old->forward_to_atomic(old); 4274 if (forward_ptr == NULL) { 4275 // Forward-to-self succeeded. 4276 4277 if (_evac_failure_closure != cl) { 4278 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag); 4279 assert(!_drain_in_progress, 4280 "Should only be true while someone holds the lock."); 4281 // Set the global evac-failure closure to the current thread's. 4282 assert(_evac_failure_closure == NULL, "Or locking has failed."); 4283 set_evac_failure_closure(cl); 4284 // Now do the common part. 4285 handle_evacuation_failure_common(old, m); 4286 // Reset to NULL. 4287 set_evac_failure_closure(NULL); 4288 } else { 4289 // The lock is already held, and this is recursive. 4290 assert(_drain_in_progress, "This should only be the recursive case."); 4291 handle_evacuation_failure_common(old, m); 4292 } 4293 return old; 4294 } else { 4295 // Forward-to-self failed. Either someone else managed to allocate 4296 // space for this object (old != forward_ptr) or they beat us in 4297 // self-forwarding it (old == forward_ptr). 4298 assert(old == forward_ptr || !obj_in_cs(forward_ptr), 4299 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" " 4300 "should not be in the CSet", 4301 (HeapWord*) old, (HeapWord*) forward_ptr)); 4302 return forward_ptr; 4303 } 4304 } 4305 4306 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) { 4307 set_evacuation_failed(true); 4308 4309 preserve_mark_if_necessary(old, m); 4310 4311 HeapRegion* r = heap_region_containing(old); 4312 if (!r->evacuation_failed()) { 4313 r->set_evacuation_failed(true); 4314 _hr_printer.evac_failure(r); 4315 } 4316 4317 push_on_evac_failure_scan_stack(old); 4318 4319 if (!_drain_in_progress) { 4320 // prevent recursion in copy_to_survivor_space() 4321 _drain_in_progress = true; 4322 drain_evac_failure_scan_stack(); 4323 _drain_in_progress = false; 4324 } 4325 } 4326 4327 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) { 4328 assert(evacuation_failed(), "Oversaving!"); 4329 // We want to call the "for_promotion_failure" version only in the 4330 // case of a promotion failure. 4331 if (m->must_be_preserved_for_promotion_failure(obj)) { 4332 _objs_with_preserved_marks.push(obj); 4333 _preserved_marks_of_objs.push(m); 4334 } 4335 } 4336 4337 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose, 4338 size_t word_size) { 4339 if (purpose == GCAllocForSurvived) { 4340 HeapWord* result = survivor_attempt_allocation(word_size); 4341 if (result != NULL) { 4342 return result; 4343 } else { 4344 // Let's try to allocate in the old gen in case we can fit the 4345 // object there. 4346 return old_attempt_allocation(word_size); 4347 } 4348 } else { 4349 assert(purpose == GCAllocForTenured, "sanity"); 4350 HeapWord* result = old_attempt_allocation(word_size); 4351 if (result != NULL) { 4352 return result; 4353 } else { 4354 // Let's try to allocate in the survivors in case we can fit the 4355 // object there. 4356 return survivor_attempt_allocation(word_size); 4357 } 4358 } 4359 4360 ShouldNotReachHere(); 4361 // Trying to keep some compilers happy. 4362 return NULL; 4363 } 4364 4365 G1ParGCAllocBuffer::G1ParGCAllocBuffer(size_t gclab_word_size) : 4366 ParGCAllocBuffer(gclab_word_size), _retired(false) { } 4367 4368 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num) 4369 : _g1h(g1h), 4370 _refs(g1h->task_queue(queue_num)), 4371 _dcq(&g1h->dirty_card_queue_set()), 4372 _ct_bs((CardTableModRefBS*)_g1h->barrier_set()), 4373 _g1_rem(g1h->g1_rem_set()), 4374 _hash_seed(17), _queue_num(queue_num), 4375 _term_attempts(0), 4376 _surviving_alloc_buffer(g1h->desired_plab_sz(GCAllocForSurvived)), 4377 _tenured_alloc_buffer(g1h->desired_plab_sz(GCAllocForTenured)), 4378 _age_table(false), 4379 _strong_roots_time(0), _term_time(0), 4380 _alloc_buffer_waste(0), _undo_waste(0) { 4381 // we allocate G1YoungSurvRateNumRegions plus one entries, since 4382 // we "sacrifice" entry 0 to keep track of surviving bytes for 4383 // non-young regions (where the age is -1) 4384 // We also add a few elements at the beginning and at the end in 4385 // an attempt to eliminate cache contention 4386 uint real_length = 1 + _g1h->g1_policy()->young_cset_region_length(); 4387 uint array_length = PADDING_ELEM_NUM + 4388 real_length + 4389 PADDING_ELEM_NUM; 4390 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length, mtGC); 4391 if (_surviving_young_words_base == NULL) 4392 vm_exit_out_of_memory(array_length * sizeof(size_t), OOM_MALLOC_ERROR, 4393 "Not enough space for young surv histo."); 4394 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM; 4395 memset(_surviving_young_words, 0, (size_t) real_length * sizeof(size_t)); 4396 4397 _alloc_buffers[GCAllocForSurvived] = &_surviving_alloc_buffer; 4398 _alloc_buffers[GCAllocForTenured] = &_tenured_alloc_buffer; 4399 4400 _start = os::elapsedTime(); 4401 } 4402 4403 void 4404 G1ParScanThreadState::print_termination_stats_hdr(outputStream* const st) 4405 { 4406 st->print_raw_cr("GC Termination Stats"); 4407 st->print_raw_cr(" elapsed --strong roots-- -------termination-------" 4408 " ------waste (KiB)------"); 4409 st->print_raw_cr("thr ms ms % ms % attempts" 4410 " total alloc undo"); 4411 st->print_raw_cr("--- --------- --------- ------ --------- ------ --------" 4412 " ------- ------- -------"); 4413 } 4414 4415 void 4416 G1ParScanThreadState::print_termination_stats(int i, 4417 outputStream* const st) const 4418 { 4419 const double elapsed_ms = elapsed_time() * 1000.0; 4420 const double s_roots_ms = strong_roots_time() * 1000.0; 4421 const double term_ms = term_time() * 1000.0; 4422 st->print_cr("%3d %9.2f %9.2f %6.2f " 4423 "%9.2f %6.2f " SIZE_FORMAT_W(8) " " 4424 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7), 4425 i, elapsed_ms, s_roots_ms, s_roots_ms * 100 / elapsed_ms, 4426 term_ms, term_ms * 100 / elapsed_ms, term_attempts(), 4427 (alloc_buffer_waste() + undo_waste()) * HeapWordSize / K, 4428 alloc_buffer_waste() * HeapWordSize / K, 4429 undo_waste() * HeapWordSize / K); 4430 } 4431 4432 #ifdef ASSERT 4433 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const { 4434 assert(ref != NULL, "invariant"); 4435 assert(UseCompressedOops, "sanity"); 4436 assert(!has_partial_array_mask(ref), err_msg("ref=" PTR_FORMAT, ref)); 4437 oop p = oopDesc::load_decode_heap_oop(ref); 4438 assert(_g1h->is_in_g1_reserved(p), 4439 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p))); 4440 return true; 4441 } 4442 4443 bool G1ParScanThreadState::verify_ref(oop* ref) const { 4444 assert(ref != NULL, "invariant"); 4445 if (has_partial_array_mask(ref)) { 4446 // Must be in the collection set--it's already been copied. 4447 oop p = clear_partial_array_mask(ref); 4448 assert(_g1h->obj_in_cs(p), 4449 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p))); 4450 } else { 4451 oop p = oopDesc::load_decode_heap_oop(ref); 4452 assert(_g1h->is_in_g1_reserved(p), 4453 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p))); 4454 } 4455 return true; 4456 } 4457 4458 bool G1ParScanThreadState::verify_task(StarTask ref) const { 4459 if (ref.is_narrow()) { 4460 return verify_ref((narrowOop*) ref); 4461 } else { 4462 return verify_ref((oop*) ref); 4463 } 4464 } 4465 #endif // ASSERT 4466 4467 void G1ParScanThreadState::trim_queue() { 4468 assert(_evac_cl != NULL, "not set"); 4469 assert(_evac_failure_cl != NULL, "not set"); 4470 assert(_partial_scan_cl != NULL, "not set"); 4471 4472 StarTask ref; 4473 do { 4474 // Drain the overflow stack first, so other threads can steal. 4475 while (refs()->pop_overflow(ref)) { 4476 deal_with_reference(ref); 4477 } 4478 4479 while (refs()->pop_local(ref)) { 4480 deal_with_reference(ref); 4481 } 4482 } while (!refs()->is_empty()); 4483 } 4484 4485 G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1, 4486 G1ParScanThreadState* par_scan_state) : 4487 _g1(g1), _g1_rem(_g1->g1_rem_set()), _cm(_g1->concurrent_mark()), 4488 _par_scan_state(par_scan_state), 4489 _worker_id(par_scan_state->queue_num()), 4490 _during_initial_mark(_g1->g1_policy()->during_initial_mark_pause()), 4491 _mark_in_progress(_g1->mark_in_progress()) { } 4492 4493 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object> 4494 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>::mark_object(oop obj) { 4495 #ifdef ASSERT 4496 HeapRegion* hr = _g1->heap_region_containing(obj); 4497 assert(hr != NULL, "sanity"); 4498 assert(!hr->in_collection_set(), "should not mark objects in the CSet"); 4499 #endif // ASSERT 4500 4501 // We know that the object is not moving so it's safe to read its size. 4502 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id); 4503 } 4504 4505 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object> 4506 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object> 4507 ::mark_forwarded_object(oop from_obj, oop to_obj) { 4508 #ifdef ASSERT 4509 assert(from_obj->is_forwarded(), "from obj should be forwarded"); 4510 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee"); 4511 assert(from_obj != to_obj, "should not be self-forwarded"); 4512 4513 HeapRegion* from_hr = _g1->heap_region_containing(from_obj); 4514 assert(from_hr != NULL, "sanity"); 4515 assert(from_hr->in_collection_set(), "from obj should be in the CSet"); 4516 4517 HeapRegion* to_hr = _g1->heap_region_containing(to_obj); 4518 assert(to_hr != NULL, "sanity"); 4519 assert(!to_hr->in_collection_set(), "should not mark objects in the CSet"); 4520 #endif // ASSERT 4521 4522 // The object might be in the process of being copied by another 4523 // worker so we cannot trust that its to-space image is 4524 // well-formed. So we have to read its size from its from-space 4525 // image which we know should not be changing. 4526 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id); 4527 } 4528 4529 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object> 4530 oop G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object> 4531 ::copy_to_survivor_space(oop old) { 4532 size_t word_sz = old->size(); 4533 HeapRegion* from_region = _g1->heap_region_containing_raw(old); 4534 // +1 to make the -1 indexes valid... 4535 int young_index = from_region->young_index_in_cset()+1; 4536 assert( (from_region->is_young() && young_index > 0) || 4537 (!from_region->is_young() && young_index == 0), "invariant" ); 4538 G1CollectorPolicy* g1p = _g1->g1_policy(); 4539 markOop m = old->mark(); 4540 int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age() 4541 : m->age(); 4542 GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age, 4543 word_sz); 4544 HeapWord* obj_ptr = _par_scan_state->allocate(alloc_purpose, word_sz); 4545 #ifndef PRODUCT 4546 // Should this evacuation fail? 4547 if (_g1->evacuation_should_fail()) { 4548 if (obj_ptr != NULL) { 4549 _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz); 4550 obj_ptr = NULL; 4551 } 4552 } 4553 #endif // !PRODUCT 4554 4555 if (obj_ptr == NULL) { 4556 // This will either forward-to-self, or detect that someone else has 4557 // installed a forwarding pointer. 4558 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure(); 4559 return _g1->handle_evacuation_failure_par(cl, old); 4560 } 4561 4562 oop obj = oop(obj_ptr); 4563 4564 // We're going to allocate linearly, so might as well prefetch ahead. 4565 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes); 4566 4567 oop forward_ptr = old->forward_to_atomic(obj); 4568 if (forward_ptr == NULL) { 4569 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz); 4570 if (g1p->track_object_age(alloc_purpose)) { 4571 // We could simply do obj->incr_age(). However, this causes a 4572 // performance issue. obj->incr_age() will first check whether 4573 // the object has a displaced mark by checking its mark word; 4574 // getting the mark word from the new location of the object 4575 // stalls. So, given that we already have the mark word and we 4576 // are about to install it anyway, it's better to increase the 4577 // age on the mark word, when the object does not have a 4578 // displaced mark word. We're not expecting many objects to have 4579 // a displaced marked word, so that case is not optimized 4580 // further (it could be...) and we simply call obj->incr_age(). 4581 4582 if (m->has_displaced_mark_helper()) { 4583 // in this case, we have to install the mark word first, 4584 // otherwise obj looks to be forwarded (the old mark word, 4585 // which contains the forward pointer, was copied) 4586 obj->set_mark(m); 4587 obj->incr_age(); 4588 } else { 4589 m = m->incr_age(); 4590 obj->set_mark(m); 4591 } 4592 _par_scan_state->age_table()->add(obj, word_sz); 4593 } else { 4594 obj->set_mark(m); 4595 } 4596 4597 size_t* surv_young_words = _par_scan_state->surviving_young_words(); 4598 surv_young_words[young_index] += word_sz; 4599 4600 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) { 4601 // We keep track of the next start index in the length field of 4602 // the to-space object. The actual length can be found in the 4603 // length field of the from-space object. 4604 arrayOop(obj)->set_length(0); 4605 oop* old_p = set_partial_array_mask(old); 4606 _par_scan_state->push_on_queue(old_p); 4607 } else { 4608 // No point in using the slower heap_region_containing() method, 4609 // given that we know obj is in the heap. 4610 _scanner.set_region(_g1->heap_region_containing_raw(obj)); 4611 obj->oop_iterate_backwards(&_scanner); 4612 } 4613 } else { 4614 _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz); 4615 obj = forward_ptr; 4616 } 4617 return obj; 4618 } 4619 4620 template <class T> 4621 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) { 4622 if (_g1->heap_region_containing_raw(new_obj)->is_young()) { 4623 _scanned_klass->record_modified_oops(); 4624 } 4625 } 4626 4627 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object> 4628 template <class T> 4629 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object> 4630 ::do_oop_work(T* p) { 4631 oop obj = oopDesc::load_decode_heap_oop(p); 4632 assert(barrier != G1BarrierRS || obj != NULL, 4633 "Precondition: G1BarrierRS implies obj is non-NULL"); 4634 4635 assert(_worker_id == _par_scan_state->queue_num(), "sanity"); 4636 4637 // here the null check is implicit in the cset_fast_test() test 4638 if (_g1->in_cset_fast_test(obj)) { 4639 oop forwardee; 4640 if (obj->is_forwarded()) { 4641 forwardee = obj->forwardee(); 4642 } else { 4643 forwardee = copy_to_survivor_space(obj); 4644 } 4645 assert(forwardee != NULL, "forwardee should not be NULL"); 4646 oopDesc::encode_store_heap_oop(p, forwardee); 4647 if (do_mark_object && forwardee != obj) { 4648 // If the object is self-forwarded we don't need to explicitly 4649 // mark it, the evacuation failure protocol will do so. 4650 mark_forwarded_object(obj, forwardee); 4651 } 4652 4653 // When scanning the RS, we only care about objs in CS. 4654 if (barrier == G1BarrierRS) { 4655 _par_scan_state->update_rs(_from, p, _worker_id); 4656 } else if (barrier == G1BarrierKlass) { 4657 do_klass_barrier(p, forwardee); 4658 } 4659 } else { 4660 // The object is not in collection set. If we're a root scanning 4661 // closure during an initial mark pause (i.e. do_mark_object will 4662 // be true) then attempt to mark the object. 4663 if (do_mark_object && _g1->is_in_g1_reserved(obj)) { 4664 mark_object(obj); 4665 } 4666 } 4667 4668 if (barrier == G1BarrierEvac && obj != NULL) { 4669 _par_scan_state->update_rs(_from, p, _worker_id); 4670 } 4671 4672 if (do_gen_barrier && obj != NULL) { 4673 par_do_barrier(p); 4674 } 4675 } 4676 4677 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(oop* p); 4678 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(narrowOop* p); 4679 4680 template <class T> void G1ParScanPartialArrayClosure::do_oop_nv(T* p) { 4681 assert(has_partial_array_mask(p), "invariant"); 4682 oop from_obj = clear_partial_array_mask(p); 4683 4684 assert(Universe::heap()->is_in_reserved(from_obj), "must be in heap."); 4685 assert(from_obj->is_objArray(), "must be obj array"); 4686 objArrayOop from_obj_array = objArrayOop(from_obj); 4687 // The from-space object contains the real length. 4688 int length = from_obj_array->length(); 4689 4690 assert(from_obj->is_forwarded(), "must be forwarded"); 4691 oop to_obj = from_obj->forwardee(); 4692 assert(from_obj != to_obj, "should not be chunking self-forwarded objects"); 4693 objArrayOop to_obj_array = objArrayOop(to_obj); 4694 // We keep track of the next start index in the length field of the 4695 // to-space object. 4696 int next_index = to_obj_array->length(); 4697 assert(0 <= next_index && next_index < length, 4698 err_msg("invariant, next index: %d, length: %d", next_index, length)); 4699 4700 int start = next_index; 4701 int end = length; 4702 int remainder = end - start; 4703 // We'll try not to push a range that's smaller than ParGCArrayScanChunk. 4704 if (remainder > 2 * ParGCArrayScanChunk) { 4705 end = start + ParGCArrayScanChunk; 4706 to_obj_array->set_length(end); 4707 // Push the remainder before we process the range in case another 4708 // worker has run out of things to do and can steal it. 4709 oop* from_obj_p = set_partial_array_mask(from_obj); 4710 _par_scan_state->push_on_queue(from_obj_p); 4711 } else { 4712 assert(length == end, "sanity"); 4713 // We'll process the final range for this object. Restore the length 4714 // so that the heap remains parsable in case of evacuation failure. 4715 to_obj_array->set_length(end); 4716 } 4717 _scanner.set_region(_g1->heap_region_containing_raw(to_obj)); 4718 // Process indexes [start,end). It will also process the header 4719 // along with the first chunk (i.e., the chunk with start == 0). 4720 // Note that at this point the length field of to_obj_array is not 4721 // correct given that we are using it to keep track of the next 4722 // start index. oop_iterate_range() (thankfully!) ignores the length 4723 // field and only relies on the start / end parameters. It does 4724 // however return the size of the object which will be incorrect. So 4725 // we have to ignore it even if we wanted to use it. 4726 to_obj_array->oop_iterate_range(&_scanner, start, end); 4727 } 4728 4729 class G1ParEvacuateFollowersClosure : public VoidClosure { 4730 protected: 4731 G1CollectedHeap* _g1h; 4732 G1ParScanThreadState* _par_scan_state; 4733 RefToScanQueueSet* _queues; 4734 ParallelTaskTerminator* _terminator; 4735 4736 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 4737 RefToScanQueueSet* queues() { return _queues; } 4738 ParallelTaskTerminator* terminator() { return _terminator; } 4739 4740 public: 4741 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h, 4742 G1ParScanThreadState* par_scan_state, 4743 RefToScanQueueSet* queues, 4744 ParallelTaskTerminator* terminator) 4745 : _g1h(g1h), _par_scan_state(par_scan_state), 4746 _queues(queues), _terminator(terminator) {} 4747 4748 void do_void(); 4749 4750 private: 4751 inline bool offer_termination(); 4752 }; 4753 4754 bool G1ParEvacuateFollowersClosure::offer_termination() { 4755 G1ParScanThreadState* const pss = par_scan_state(); 4756 pss->start_term_time(); 4757 const bool res = terminator()->offer_termination(); 4758 pss->end_term_time(); 4759 return res; 4760 } 4761 4762 void G1ParEvacuateFollowersClosure::do_void() { 4763 StarTask stolen_task; 4764 G1ParScanThreadState* const pss = par_scan_state(); 4765 pss->trim_queue(); 4766 4767 do { 4768 while (queues()->steal(pss->queue_num(), pss->hash_seed(), stolen_task)) { 4769 assert(pss->verify_task(stolen_task), "sanity"); 4770 if (stolen_task.is_narrow()) { 4771 pss->deal_with_reference((narrowOop*) stolen_task); 4772 } else { 4773 pss->deal_with_reference((oop*) stolen_task); 4774 } 4775 4776 // We've just processed a reference and we might have made 4777 // available new entries on the queues. So we have to make sure 4778 // we drain the queues as necessary. 4779 pss->trim_queue(); 4780 } 4781 } while (!offer_termination()); 4782 4783 pss->retire_alloc_buffers(); 4784 } 4785 4786 class G1KlassScanClosure : public KlassClosure { 4787 G1ParCopyHelper* _closure; 4788 bool _process_only_dirty; 4789 int _count; 4790 public: 4791 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty) 4792 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {} 4793 void do_klass(Klass* klass) { 4794 // If the klass has not been dirtied we know that there's 4795 // no references into the young gen and we can skip it. 4796 if (!_process_only_dirty || klass->has_modified_oops()) { 4797 // Clean the klass since we're going to scavenge all the metadata. 4798 klass->clear_modified_oops(); 4799 4800 // Tell the closure that this klass is the Klass to scavenge 4801 // and is the one to dirty if oops are left pointing into the young gen. 4802 _closure->set_scanned_klass(klass); 4803 4804 klass->oops_do(_closure); 4805 4806 _closure->set_scanned_klass(NULL); 4807 } 4808 _count++; 4809 } 4810 }; 4811 4812 class G1ParTask : public AbstractGangTask { 4813 protected: 4814 G1CollectedHeap* _g1h; 4815 RefToScanQueueSet *_queues; 4816 ParallelTaskTerminator _terminator; 4817 uint _n_workers; 4818 4819 Mutex _stats_lock; 4820 Mutex* stats_lock() { return &_stats_lock; } 4821 4822 size_t getNCards() { 4823 return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1) 4824 / G1BlockOffsetSharedArray::N_bytes; 4825 } 4826 4827 public: 4828 G1ParTask(G1CollectedHeap* g1h, 4829 RefToScanQueueSet *task_queues) 4830 : AbstractGangTask("G1 collection"), 4831 _g1h(g1h), 4832 _queues(task_queues), 4833 _terminator(0, _queues), 4834 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true) 4835 {} 4836 4837 RefToScanQueueSet* queues() { return _queues; } 4838 4839 RefToScanQueue *work_queue(int i) { 4840 return queues()->queue(i); 4841 } 4842 4843 ParallelTaskTerminator* terminator() { return &_terminator; } 4844 4845 virtual void set_for_termination(int active_workers) { 4846 // This task calls set_n_termination() in par_non_clean_card_iterate_work() 4847 // in the young space (_par_seq_tasks) in the G1 heap 4848 // for SequentialSubTasksDone. 4849 // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap 4850 // both of which need setting by set_n_termination(). 4851 _g1h->SharedHeap::set_n_termination(active_workers); 4852 _g1h->set_n_termination(active_workers); 4853 terminator()->reset_for_reuse(active_workers); 4854 _n_workers = active_workers; 4855 } 4856 4857 void work(uint worker_id) { 4858 if (worker_id >= _n_workers) return; // no work needed this round 4859 4860 double start_time_ms = os::elapsedTime() * 1000.0; 4861 _g1h->g1_policy()->phase_times()->record_gc_worker_start_time(worker_id, start_time_ms); 4862 4863 { 4864 ResourceMark rm; 4865 HandleMark hm; 4866 4867 ReferenceProcessor* rp = _g1h->ref_processor_stw(); 4868 4869 G1ParScanThreadState pss(_g1h, worker_id); 4870 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, rp); 4871 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp); 4872 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, rp); 4873 4874 pss.set_evac_closure(&scan_evac_cl); 4875 pss.set_evac_failure_closure(&evac_failure_cl); 4876 pss.set_partial_scan_closure(&partial_scan_cl); 4877 4878 G1ParScanExtRootClosure only_scan_root_cl(_g1h, &pss, rp); 4879 G1ParScanMetadataClosure only_scan_metadata_cl(_g1h, &pss, rp); 4880 4881 G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss, rp); 4882 G1ParScanAndMarkMetadataClosure scan_mark_metadata_cl(_g1h, &pss, rp); 4883 4884 bool only_young = _g1h->g1_policy()->gcs_are_young(); 4885 G1KlassScanClosure scan_mark_klasses_cl_s(&scan_mark_metadata_cl, false); 4886 G1KlassScanClosure only_scan_klasses_cl_s(&only_scan_metadata_cl, only_young); 4887 4888 OopClosure* scan_root_cl = &only_scan_root_cl; 4889 G1KlassScanClosure* scan_klasses_cl = &only_scan_klasses_cl_s; 4890 4891 if (_g1h->g1_policy()->during_initial_mark_pause()) { 4892 // We also need to mark copied objects. 4893 scan_root_cl = &scan_mark_root_cl; 4894 scan_klasses_cl = &scan_mark_klasses_cl_s; 4895 } 4896 4897 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss); 4898 4899 int so = SharedHeap::SO_AllClasses | SharedHeap::SO_Strings | SharedHeap::SO_CodeCache; 4900 4901 pss.start_strong_roots(); 4902 _g1h->g1_process_strong_roots(/* is scavenging */ true, 4903 SharedHeap::ScanningOption(so), 4904 scan_root_cl, 4905 &push_heap_rs_cl, 4906 scan_klasses_cl, 4907 worker_id); 4908 pss.end_strong_roots(); 4909 4910 { 4911 double start = os::elapsedTime(); 4912 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator); 4913 evac.do_void(); 4914 double elapsed_ms = (os::elapsedTime()-start)*1000.0; 4915 double term_ms = pss.term_time()*1000.0; 4916 _g1h->g1_policy()->phase_times()->add_obj_copy_time(worker_id, elapsed_ms-term_ms); 4917 _g1h->g1_policy()->phase_times()->record_termination(worker_id, term_ms, pss.term_attempts()); 4918 } 4919 _g1h->g1_policy()->record_thread_age_table(pss.age_table()); 4920 _g1h->update_surviving_young_words(pss.surviving_young_words()+1); 4921 4922 if (ParallelGCVerbose) { 4923 MutexLocker x(stats_lock()); 4924 pss.print_termination_stats(worker_id); 4925 } 4926 4927 assert(pss.refs()->is_empty(), "should be empty"); 4928 4929 // Close the inner scope so that the ResourceMark and HandleMark 4930 // destructors are executed here and are included as part of the 4931 // "GC Worker Time". 4932 } 4933 4934 double end_time_ms = os::elapsedTime() * 1000.0; 4935 _g1h->g1_policy()->phase_times()->record_gc_worker_end_time(worker_id, end_time_ms); 4936 } 4937 }; 4938 4939 // *** Common G1 Evacuation Stuff 4940 4941 // Closures that support the filtering of CodeBlobs scanned during 4942 // external root scanning. 4943 4944 // Closure applied to reference fields in code blobs (specifically nmethods) 4945 // to determine whether an nmethod contains references that point into 4946 // the collection set. Used as a predicate when walking code roots so 4947 // that only nmethods that point into the collection set are added to the 4948 // 'marked' list. 4949 4950 class G1FilteredCodeBlobToOopClosure : public CodeBlobToOopClosure { 4951 4952 class G1PointsIntoCSOopClosure : public OopClosure { 4953 G1CollectedHeap* _g1; 4954 bool _points_into_cs; 4955 public: 4956 G1PointsIntoCSOopClosure(G1CollectedHeap* g1) : 4957 _g1(g1), _points_into_cs(false) { } 4958 4959 bool points_into_cs() const { return _points_into_cs; } 4960 4961 template <class T> 4962 void do_oop_nv(T* p) { 4963 if (!_points_into_cs) { 4964 T heap_oop = oopDesc::load_heap_oop(p); 4965 if (!oopDesc::is_null(heap_oop) && 4966 _g1->in_cset_fast_test(oopDesc::decode_heap_oop_not_null(heap_oop))) { 4967 _points_into_cs = true; 4968 } 4969 } 4970 } 4971 4972 virtual void do_oop(oop* p) { do_oop_nv(p); } 4973 virtual void do_oop(narrowOop* p) { do_oop_nv(p); } 4974 }; 4975 4976 G1CollectedHeap* _g1; 4977 4978 public: 4979 G1FilteredCodeBlobToOopClosure(G1CollectedHeap* g1, OopClosure* cl) : 4980 CodeBlobToOopClosure(cl, true), _g1(g1) { } 4981 4982 virtual void do_code_blob(CodeBlob* cb) { 4983 nmethod* nm = cb->as_nmethod_or_null(); 4984 if (nm != NULL && !(nm->test_oops_do_mark())) { 4985 G1PointsIntoCSOopClosure predicate_cl(_g1); 4986 nm->oops_do(&predicate_cl); 4987 4988 if (predicate_cl.points_into_cs()) { 4989 // At least one of the reference fields or the oop relocations 4990 // in the nmethod points into the collection set. We have to 4991 // 'mark' this nmethod. 4992 // Note: Revisit the following if CodeBlobToOopClosure::do_code_blob() 4993 // or MarkingCodeBlobClosure::do_code_blob() change. 4994 if (!nm->test_set_oops_do_mark()) { 4995 do_newly_marked_nmethod(nm); 4996 } 4997 } 4998 } 4999 } 5000 }; 5001 5002 // This method is run in a GC worker. 5003 5004 void 5005 G1CollectedHeap:: 5006 g1_process_strong_roots(bool is_scavenging, 5007 ScanningOption so, 5008 OopClosure* scan_non_heap_roots, 5009 OopsInHeapRegionClosure* scan_rs, 5010 G1KlassScanClosure* scan_klasses, 5011 int worker_i) { 5012 5013 // First scan the strong roots 5014 double ext_roots_start = os::elapsedTime(); 5015 double closure_app_time_sec = 0.0; 5016 5017 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots); 5018 5019 // Walk the code cache w/o buffering, because StarTask cannot handle 5020 // unaligned oop locations. 5021 G1FilteredCodeBlobToOopClosure eager_scan_code_roots(this, scan_non_heap_roots); 5022 5023 process_strong_roots(false, // no scoping; this is parallel code 5024 is_scavenging, so, 5025 &buf_scan_non_heap_roots, 5026 &eager_scan_code_roots, 5027 scan_klasses 5028 ); 5029 5030 // Now the CM ref_processor roots. 5031 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) { 5032 // We need to treat the discovered reference lists of the 5033 // concurrent mark ref processor as roots and keep entries 5034 // (which are added by the marking threads) on them live 5035 // until they can be processed at the end of marking. 5036 ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots); 5037 } 5038 5039 // Finish up any enqueued closure apps (attributed as object copy time). 5040 buf_scan_non_heap_roots.done(); 5041 5042 double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds(); 5043 5044 g1_policy()->phase_times()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0); 5045 5046 double ext_root_time_ms = 5047 ((os::elapsedTime() - ext_roots_start) - obj_copy_time_sec) * 1000.0; 5048 5049 g1_policy()->phase_times()->record_ext_root_scan_time(worker_i, ext_root_time_ms); 5050 5051 // During conc marking we have to filter the per-thread SATB buffers 5052 // to make sure we remove any oops into the CSet (which will show up 5053 // as implicitly live). 5054 double satb_filtering_ms = 0.0; 5055 if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers)) { 5056 if (mark_in_progress()) { 5057 double satb_filter_start = os::elapsedTime(); 5058 5059 JavaThread::satb_mark_queue_set().filter_thread_buffers(); 5060 5061 satb_filtering_ms = (os::elapsedTime() - satb_filter_start) * 1000.0; 5062 } 5063 } 5064 g1_policy()->phase_times()->record_satb_filtering_time(worker_i, satb_filtering_ms); 5065 5066 // Now scan the complement of the collection set. 5067 if (scan_rs != NULL) { 5068 g1_rem_set()->oops_into_collection_set_do(scan_rs, worker_i); 5069 } 5070 _process_strong_tasks->all_tasks_completed(); 5071 } 5072 5073 void 5074 G1CollectedHeap::g1_process_weak_roots(OopClosure* root_closure) { 5075 CodeBlobToOopClosure roots_in_blobs(root_closure, /*do_marking=*/ false); 5076 SharedHeap::process_weak_roots(root_closure, &roots_in_blobs); 5077 } 5078 5079 // Weak Reference Processing support 5080 5081 // An always "is_alive" closure that is used to preserve referents. 5082 // If the object is non-null then it's alive. Used in the preservation 5083 // of referent objects that are pointed to by reference objects 5084 // discovered by the CM ref processor. 5085 class G1AlwaysAliveClosure: public BoolObjectClosure { 5086 G1CollectedHeap* _g1; 5087 public: 5088 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 5089 void do_object(oop p) { assert(false, "Do not call."); } 5090 bool do_object_b(oop p) { 5091 if (p != NULL) { 5092 return true; 5093 } 5094 return false; 5095 } 5096 }; 5097 5098 bool G1STWIsAliveClosure::do_object_b(oop p) { 5099 // An object is reachable if it is outside the collection set, 5100 // or is inside and copied. 5101 return !_g1->obj_in_cs(p) || p->is_forwarded(); 5102 } 5103 5104 // Non Copying Keep Alive closure 5105 class G1KeepAliveClosure: public OopClosure { 5106 G1CollectedHeap* _g1; 5107 public: 5108 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 5109 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } 5110 void do_oop( oop* p) { 5111 oop obj = *p; 5112 5113 if (_g1->obj_in_cs(obj)) { 5114 assert( obj->is_forwarded(), "invariant" ); 5115 *p = obj->forwardee(); 5116 } 5117 } 5118 }; 5119 5120 // Copying Keep Alive closure - can be called from both 5121 // serial and parallel code as long as different worker 5122 // threads utilize different G1ParScanThreadState instances 5123 // and different queues. 5124 5125 class G1CopyingKeepAliveClosure: public OopClosure { 5126 G1CollectedHeap* _g1h; 5127 OopClosure* _copy_non_heap_obj_cl; 5128 OopsInHeapRegionClosure* _copy_metadata_obj_cl; 5129 G1ParScanThreadState* _par_scan_state; 5130 5131 public: 5132 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, 5133 OopClosure* non_heap_obj_cl, 5134 OopsInHeapRegionClosure* metadata_obj_cl, 5135 G1ParScanThreadState* pss): 5136 _g1h(g1h), 5137 _copy_non_heap_obj_cl(non_heap_obj_cl), 5138 _copy_metadata_obj_cl(metadata_obj_cl), 5139 _par_scan_state(pss) 5140 {} 5141 5142 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 5143 virtual void do_oop( oop* p) { do_oop_work(p); } 5144 5145 template <class T> void do_oop_work(T* p) { 5146 oop obj = oopDesc::load_decode_heap_oop(p); 5147 5148 if (_g1h->obj_in_cs(obj)) { 5149 // If the referent object has been forwarded (either copied 5150 // to a new location or to itself in the event of an 5151 // evacuation failure) then we need to update the reference 5152 // field and, if both reference and referent are in the G1 5153 // heap, update the RSet for the referent. 5154 // 5155 // If the referent has not been forwarded then we have to keep 5156 // it alive by policy. Therefore we have copy the referent. 5157 // 5158 // If the reference field is in the G1 heap then we can push 5159 // on the PSS queue. When the queue is drained (after each 5160 // phase of reference processing) the object and it's followers 5161 // will be copied, the reference field set to point to the 5162 // new location, and the RSet updated. Otherwise we need to 5163 // use the the non-heap or metadata closures directly to copy 5164 // the refernt object and update the pointer, while avoiding 5165 // updating the RSet. 5166 5167 if (_g1h->is_in_g1_reserved(p)) { 5168 _par_scan_state->push_on_queue(p); 5169 } else { 5170 assert(!ClassLoaderDataGraph::contains((address)p), 5171 err_msg("Otherwise need to call _copy_metadata_obj_cl->do_oop(p) " 5172 PTR_FORMAT, p)); 5173 _copy_non_heap_obj_cl->do_oop(p); 5174 } 5175 } 5176 } 5177 }; 5178 5179 // Serial drain queue closure. Called as the 'complete_gc' 5180 // closure for each discovered list in some of the 5181 // reference processing phases. 5182 5183 class G1STWDrainQueueClosure: public VoidClosure { 5184 protected: 5185 G1CollectedHeap* _g1h; 5186 G1ParScanThreadState* _par_scan_state; 5187 5188 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 5189 5190 public: 5191 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : 5192 _g1h(g1h), 5193 _par_scan_state(pss) 5194 { } 5195 5196 void do_void() { 5197 G1ParScanThreadState* const pss = par_scan_state(); 5198 pss->trim_queue(); 5199 } 5200 }; 5201 5202 // Parallel Reference Processing closures 5203 5204 // Implementation of AbstractRefProcTaskExecutor for parallel reference 5205 // processing during G1 evacuation pauses. 5206 5207 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 5208 private: 5209 G1CollectedHeap* _g1h; 5210 RefToScanQueueSet* _queues; 5211 FlexibleWorkGang* _workers; 5212 int _active_workers; 5213 5214 public: 5215 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, 5216 FlexibleWorkGang* workers, 5217 RefToScanQueueSet *task_queues, 5218 int n_workers) : 5219 _g1h(g1h), 5220 _queues(task_queues), 5221 _workers(workers), 5222 _active_workers(n_workers) 5223 { 5224 assert(n_workers > 0, "shouldn't call this otherwise"); 5225 } 5226 5227 // Executes the given task using concurrent marking worker threads. 5228 virtual void execute(ProcessTask& task); 5229 virtual void execute(EnqueueTask& task); 5230 }; 5231 5232 // Gang task for possibly parallel reference processing 5233 5234 class G1STWRefProcTaskProxy: public AbstractGangTask { 5235 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 5236 ProcessTask& _proc_task; 5237 G1CollectedHeap* _g1h; 5238 RefToScanQueueSet *_task_queues; 5239 ParallelTaskTerminator* _terminator; 5240 5241 public: 5242 G1STWRefProcTaskProxy(ProcessTask& proc_task, 5243 G1CollectedHeap* g1h, 5244 RefToScanQueueSet *task_queues, 5245 ParallelTaskTerminator* terminator) : 5246 AbstractGangTask("Process reference objects in parallel"), 5247 _proc_task(proc_task), 5248 _g1h(g1h), 5249 _task_queues(task_queues), 5250 _terminator(terminator) 5251 {} 5252 5253 virtual void work(uint worker_id) { 5254 // The reference processing task executed by a single worker. 5255 ResourceMark rm; 5256 HandleMark hm; 5257 5258 G1STWIsAliveClosure is_alive(_g1h); 5259 5260 G1ParScanThreadState pss(_g1h, worker_id); 5261 5262 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, NULL); 5263 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL); 5264 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, NULL); 5265 5266 pss.set_evac_closure(&scan_evac_cl); 5267 pss.set_evac_failure_closure(&evac_failure_cl); 5268 pss.set_partial_scan_closure(&partial_scan_cl); 5269 5270 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL); 5271 G1ParScanMetadataClosure only_copy_metadata_cl(_g1h, &pss, NULL); 5272 5273 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL); 5274 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL); 5275 5276 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5277 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl; 5278 5279 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5280 // We also need to mark copied objects. 5281 copy_non_heap_cl = ©_mark_non_heap_cl; 5282 copy_metadata_cl = ©_mark_metadata_cl; 5283 } 5284 5285 // Keep alive closure. 5286 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss); 5287 5288 // Complete GC closure 5289 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator); 5290 5291 // Call the reference processing task's work routine. 5292 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); 5293 5294 // Note we cannot assert that the refs array is empty here as not all 5295 // of the processing tasks (specifically phase2 - pp2_work) execute 5296 // the complete_gc closure (which ordinarily would drain the queue) so 5297 // the queue may not be empty. 5298 } 5299 }; 5300 5301 // Driver routine for parallel reference processing. 5302 // Creates an instance of the ref processing gang 5303 // task and has the worker threads execute it. 5304 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) { 5305 assert(_workers != NULL, "Need parallel worker threads."); 5306 5307 ParallelTaskTerminator terminator(_active_workers, _queues); 5308 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator); 5309 5310 _g1h->set_par_threads(_active_workers); 5311 _workers->run_task(&proc_task_proxy); 5312 _g1h->set_par_threads(0); 5313 } 5314 5315 // Gang task for parallel reference enqueueing. 5316 5317 class G1STWRefEnqueueTaskProxy: public AbstractGangTask { 5318 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; 5319 EnqueueTask& _enq_task; 5320 5321 public: 5322 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) : 5323 AbstractGangTask("Enqueue reference objects in parallel"), 5324 _enq_task(enq_task) 5325 { } 5326 5327 virtual void work(uint worker_id) { 5328 _enq_task.work(worker_id); 5329 } 5330 }; 5331 5332 // Driver routine for parallel reference enqueing. 5333 // Creates an instance of the ref enqueueing gang 5334 // task and has the worker threads execute it. 5335 5336 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) { 5337 assert(_workers != NULL, "Need parallel worker threads."); 5338 5339 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task); 5340 5341 _g1h->set_par_threads(_active_workers); 5342 _workers->run_task(&enq_task_proxy); 5343 _g1h->set_par_threads(0); 5344 } 5345 5346 // End of weak reference support closures 5347 5348 // Abstract task used to preserve (i.e. copy) any referent objects 5349 // that are in the collection set and are pointed to by reference 5350 // objects discovered by the CM ref processor. 5351 5352 class G1ParPreserveCMReferentsTask: public AbstractGangTask { 5353 protected: 5354 G1CollectedHeap* _g1h; 5355 RefToScanQueueSet *_queues; 5356 ParallelTaskTerminator _terminator; 5357 uint _n_workers; 5358 5359 public: 5360 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) : 5361 AbstractGangTask("ParPreserveCMReferents"), 5362 _g1h(g1h), 5363 _queues(task_queues), 5364 _terminator(workers, _queues), 5365 _n_workers(workers) 5366 { } 5367 5368 void work(uint worker_id) { 5369 ResourceMark rm; 5370 HandleMark hm; 5371 5372 G1ParScanThreadState pss(_g1h, worker_id); 5373 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, NULL); 5374 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL); 5375 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, NULL); 5376 5377 pss.set_evac_closure(&scan_evac_cl); 5378 pss.set_evac_failure_closure(&evac_failure_cl); 5379 pss.set_partial_scan_closure(&partial_scan_cl); 5380 5381 assert(pss.refs()->is_empty(), "both queue and overflow should be empty"); 5382 5383 5384 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL); 5385 G1ParScanMetadataClosure only_copy_metadata_cl(_g1h, &pss, NULL); 5386 5387 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL); 5388 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL); 5389 5390 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5391 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl; 5392 5393 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5394 // We also need to mark copied objects. 5395 copy_non_heap_cl = ©_mark_non_heap_cl; 5396 copy_metadata_cl = ©_mark_metadata_cl; 5397 } 5398 5399 // Is alive closure 5400 G1AlwaysAliveClosure always_alive(_g1h); 5401 5402 // Copying keep alive closure. Applied to referent objects that need 5403 // to be copied. 5404 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss); 5405 5406 ReferenceProcessor* rp = _g1h->ref_processor_cm(); 5407 5408 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q(); 5409 uint stride = MIN2(MAX2(_n_workers, 1U), limit); 5410 5411 // limit is set using max_num_q() - which was set using ParallelGCThreads. 5412 // So this must be true - but assert just in case someone decides to 5413 // change the worker ids. 5414 assert(0 <= worker_id && worker_id < limit, "sanity"); 5415 assert(!rp->discovery_is_atomic(), "check this code"); 5416 5417 // Select discovered lists [i, i+stride, i+2*stride,...,limit) 5418 for (uint idx = worker_id; idx < limit; idx += stride) { 5419 DiscoveredList& ref_list = rp->discovered_refs()[idx]; 5420 5421 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive); 5422 while (iter.has_next()) { 5423 // Since discovery is not atomic for the CM ref processor, we 5424 // can see some null referent objects. 5425 iter.load_ptrs(DEBUG_ONLY(true)); 5426 oop ref = iter.obj(); 5427 5428 // This will filter nulls. 5429 if (iter.is_referent_alive()) { 5430 iter.make_referent_alive(); 5431 } 5432 iter.move_to_next(); 5433 } 5434 } 5435 5436 // Drain the queue - which may cause stealing 5437 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator); 5438 drain_queue.do_void(); 5439 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure 5440 assert(pss.refs()->is_empty(), "should be"); 5441 } 5442 }; 5443 5444 // Weak Reference processing during an evacuation pause (part 1). 5445 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) { 5446 double ref_proc_start = os::elapsedTime(); 5447 5448 ReferenceProcessor* rp = _ref_processor_stw; 5449 assert(rp->discovery_enabled(), "should have been enabled"); 5450 5451 // Any reference objects, in the collection set, that were 'discovered' 5452 // by the CM ref processor should have already been copied (either by 5453 // applying the external root copy closure to the discovered lists, or 5454 // by following an RSet entry). 5455 // 5456 // But some of the referents, that are in the collection set, that these 5457 // reference objects point to may not have been copied: the STW ref 5458 // processor would have seen that the reference object had already 5459 // been 'discovered' and would have skipped discovering the reference, 5460 // but would not have treated the reference object as a regular oop. 5461 // As a reult the copy closure would not have been applied to the 5462 // referent object. 5463 // 5464 // We need to explicitly copy these referent objects - the references 5465 // will be processed at the end of remarking. 5466 // 5467 // We also need to do this copying before we process the reference 5468 // objects discovered by the STW ref processor in case one of these 5469 // referents points to another object which is also referenced by an 5470 // object discovered by the STW ref processor. 5471 5472 assert(!G1CollectedHeap::use_parallel_gc_threads() || 5473 no_of_gc_workers == workers()->active_workers(), 5474 "Need to reset active GC workers"); 5475 5476 set_par_threads(no_of_gc_workers); 5477 G1ParPreserveCMReferentsTask keep_cm_referents(this, 5478 no_of_gc_workers, 5479 _task_queues); 5480 5481 if (G1CollectedHeap::use_parallel_gc_threads()) { 5482 workers()->run_task(&keep_cm_referents); 5483 } else { 5484 keep_cm_referents.work(0); 5485 } 5486 5487 set_par_threads(0); 5488 5489 // Closure to test whether a referent is alive. 5490 G1STWIsAliveClosure is_alive(this); 5491 5492 // Even when parallel reference processing is enabled, the processing 5493 // of JNI refs is serial and performed serially by the current thread 5494 // rather than by a worker. The following PSS will be used for processing 5495 // JNI refs. 5496 5497 // Use only a single queue for this PSS. 5498 G1ParScanThreadState pss(this, 0); 5499 5500 // We do not embed a reference processor in the copying/scanning 5501 // closures while we're actually processing the discovered 5502 // reference objects. 5503 G1ParScanHeapEvacClosure scan_evac_cl(this, &pss, NULL); 5504 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL); 5505 G1ParScanPartialArrayClosure partial_scan_cl(this, &pss, NULL); 5506 5507 pss.set_evac_closure(&scan_evac_cl); 5508 pss.set_evac_failure_closure(&evac_failure_cl); 5509 pss.set_partial_scan_closure(&partial_scan_cl); 5510 5511 assert(pss.refs()->is_empty(), "pre-condition"); 5512 5513 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL); 5514 G1ParScanMetadataClosure only_copy_metadata_cl(this, &pss, NULL); 5515 5516 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL); 5517 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(this, &pss, NULL); 5518 5519 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5520 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl; 5521 5522 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5523 // We also need to mark copied objects. 5524 copy_non_heap_cl = ©_mark_non_heap_cl; 5525 copy_metadata_cl = ©_mark_metadata_cl; 5526 } 5527 5528 // Keep alive closure. 5529 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, copy_metadata_cl, &pss); 5530 5531 // Serial Complete GC closure 5532 G1STWDrainQueueClosure drain_queue(this, &pss); 5533 5534 // Setup the soft refs policy... 5535 rp->setup_policy(false); 5536 5537 if (!rp->processing_is_mt()) { 5538 // Serial reference processing... 5539 rp->process_discovered_references(&is_alive, 5540 &keep_alive, 5541 &drain_queue, 5542 NULL); 5543 } else { 5544 // Parallel reference processing 5545 assert(rp->num_q() == no_of_gc_workers, "sanity"); 5546 assert(no_of_gc_workers <= rp->max_num_q(), "sanity"); 5547 5548 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers); 5549 rp->process_discovered_references(&is_alive, &keep_alive, &drain_queue, &par_task_executor); 5550 } 5551 5552 // We have completed copying any necessary live referent objects 5553 // (that were not copied during the actual pause) so we can 5554 // retire any active alloc buffers 5555 pss.retire_alloc_buffers(); 5556 assert(pss.refs()->is_empty(), "both queue and overflow should be empty"); 5557 5558 double ref_proc_time = os::elapsedTime() - ref_proc_start; 5559 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 5560 } 5561 5562 // Weak Reference processing during an evacuation pause (part 2). 5563 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) { 5564 double ref_enq_start = os::elapsedTime(); 5565 5566 ReferenceProcessor* rp = _ref_processor_stw; 5567 assert(!rp->discovery_enabled(), "should have been disabled as part of processing"); 5568 5569 // Now enqueue any remaining on the discovered lists on to 5570 // the pending list. 5571 if (!rp->processing_is_mt()) { 5572 // Serial reference processing... 5573 rp->enqueue_discovered_references(); 5574 } else { 5575 // Parallel reference enqueuing 5576 5577 assert(no_of_gc_workers == workers()->active_workers(), 5578 "Need to reset active workers"); 5579 assert(rp->num_q() == no_of_gc_workers, "sanity"); 5580 assert(no_of_gc_workers <= rp->max_num_q(), "sanity"); 5581 5582 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers); 5583 rp->enqueue_discovered_references(&par_task_executor); 5584 } 5585 5586 rp->verify_no_references_recorded(); 5587 assert(!rp->discovery_enabled(), "should have been disabled"); 5588 5589 // FIXME 5590 // CM's reference processing also cleans up the string and symbol tables. 5591 // Should we do that here also? We could, but it is a serial operation 5592 // and could signicantly increase the pause time. 5593 5594 double ref_enq_time = os::elapsedTime() - ref_enq_start; 5595 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0); 5596 } 5597 5598 void G1CollectedHeap::evacuate_collection_set() { 5599 _expand_heap_after_alloc_failure = true; 5600 set_evacuation_failed(false); 5601 5602 // Should G1EvacuationFailureALot be in effect for this GC? 5603 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) 5604 5605 g1_rem_set()->prepare_for_oops_into_collection_set_do(); 5606 concurrent_g1_refine()->set_use_cache(false); 5607 concurrent_g1_refine()->clear_hot_cache_claimed_index(); 5608 5609 uint n_workers; 5610 if (G1CollectedHeap::use_parallel_gc_threads()) { 5611 n_workers = 5612 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 5613 workers()->active_workers(), 5614 Threads::number_of_non_daemon_threads()); 5615 assert(UseDynamicNumberOfGCThreads || 5616 n_workers == workers()->total_workers(), 5617 "If not dynamic should be using all the workers"); 5618 workers()->set_active_workers(n_workers); 5619 set_par_threads(n_workers); 5620 } else { 5621 assert(n_par_threads() == 0, 5622 "Should be the original non-parallel value"); 5623 n_workers = 1; 5624 } 5625 5626 G1ParTask g1_par_task(this, _task_queues); 5627 5628 init_for_evac_failure(NULL); 5629 5630 rem_set()->prepare_for_younger_refs_iterate(true); 5631 5632 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty"); 5633 double start_par_time_sec = os::elapsedTime(); 5634 double end_par_time_sec; 5635 5636 { 5637 StrongRootsScope srs(this); 5638 5639 if (G1CollectedHeap::use_parallel_gc_threads()) { 5640 // The individual threads will set their evac-failure closures. 5641 if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr(); 5642 // These tasks use ShareHeap::_process_strong_tasks 5643 assert(UseDynamicNumberOfGCThreads || 5644 workers()->active_workers() == workers()->total_workers(), 5645 "If not dynamic should be using all the workers"); 5646 workers()->run_task(&g1_par_task); 5647 } else { 5648 g1_par_task.set_for_termination(n_workers); 5649 g1_par_task.work(0); 5650 } 5651 end_par_time_sec = os::elapsedTime(); 5652 5653 // Closing the inner scope will execute the destructor 5654 // for the StrongRootsScope object. We record the current 5655 // elapsed time before closing the scope so that time 5656 // taken for the SRS destructor is NOT included in the 5657 // reported parallel time. 5658 } 5659 5660 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0; 5661 g1_policy()->phase_times()->record_par_time(par_time_ms); 5662 5663 double code_root_fixup_time_ms = 5664 (os::elapsedTime() - end_par_time_sec) * 1000.0; 5665 g1_policy()->phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms); 5666 5667 set_par_threads(0); 5668 5669 // Process any discovered reference objects - we have 5670 // to do this _before_ we retire the GC alloc regions 5671 // as we may have to copy some 'reachable' referent 5672 // objects (and their reachable sub-graphs) that were 5673 // not copied during the pause. 5674 process_discovered_references(n_workers); 5675 5676 // Weak root processing. 5677 // Note: when JSR 292 is enabled and code blobs can contain 5678 // non-perm oops then we will need to process the code blobs 5679 // here too. 5680 { 5681 G1STWIsAliveClosure is_alive(this); 5682 G1KeepAliveClosure keep_alive(this); 5683 JNIHandles::weak_oops_do(&is_alive, &keep_alive); 5684 } 5685 5686 release_gc_alloc_regions(n_workers); 5687 g1_rem_set()->cleanup_after_oops_into_collection_set_do(); 5688 5689 concurrent_g1_refine()->clear_hot_cache(); 5690 concurrent_g1_refine()->set_use_cache(true); 5691 5692 finalize_for_evac_failure(); 5693 5694 if (evacuation_failed()) { 5695 remove_self_forwarding_pointers(); 5696 5697 // Reset the G1EvacuationFailureALot counters and flags 5698 // Note: the values are reset only when an actual 5699 // evacuation failure occurs. 5700 NOT_PRODUCT(reset_evacuation_should_fail();) 5701 } 5702 5703 // Enqueue any remaining references remaining on the STW 5704 // reference processor's discovered lists. We need to do 5705 // this after the card table is cleaned (and verified) as 5706 // the act of enqueuing entries on to the pending list 5707 // will log these updates (and dirty their associated 5708 // cards). We need these updates logged to update any 5709 // RSets. 5710 enqueue_discovered_references(n_workers); 5711 5712 if (G1DeferredRSUpdate) { 5713 RedirtyLoggedCardTableEntryFastClosure redirty; 5714 dirty_card_queue_set().set_closure(&redirty); 5715 dirty_card_queue_set().apply_closure_to_all_completed_buffers(); 5716 5717 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set(); 5718 dcq.merge_bufferlists(&dirty_card_queue_set()); 5719 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed"); 5720 } 5721 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 5722 } 5723 5724 void G1CollectedHeap::free_region_if_empty(HeapRegion* hr, 5725 size_t* pre_used, 5726 FreeRegionList* free_list, 5727 OldRegionSet* old_proxy_set, 5728 HumongousRegionSet* humongous_proxy_set, 5729 HRRSCleanupTask* hrrs_cleanup_task, 5730 bool par) { 5731 if (hr->used() > 0 && hr->max_live_bytes() == 0 && !hr->is_young()) { 5732 if (hr->isHumongous()) { 5733 assert(hr->startsHumongous(), "we should only see starts humongous"); 5734 free_humongous_region(hr, pre_used, free_list, humongous_proxy_set, par); 5735 } else { 5736 _old_set.remove_with_proxy(hr, old_proxy_set); 5737 free_region(hr, pre_used, free_list, par); 5738 } 5739 } else { 5740 hr->rem_set()->do_cleanup_work(hrrs_cleanup_task); 5741 } 5742 } 5743 5744 void G1CollectedHeap::free_region(HeapRegion* hr, 5745 size_t* pre_used, 5746 FreeRegionList* free_list, 5747 bool par) { 5748 assert(!hr->isHumongous(), "this is only for non-humongous regions"); 5749 assert(!hr->is_empty(), "the region should not be empty"); 5750 assert(free_list != NULL, "pre-condition"); 5751 5752 *pre_used += hr->used(); 5753 hr->hr_clear(par, true /* clear_space */); 5754 free_list->add_as_head(hr); 5755 } 5756 5757 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 5758 size_t* pre_used, 5759 FreeRegionList* free_list, 5760 HumongousRegionSet* humongous_proxy_set, 5761 bool par) { 5762 assert(hr->startsHumongous(), "this is only for starts humongous regions"); 5763 assert(free_list != NULL, "pre-condition"); 5764 assert(humongous_proxy_set != NULL, "pre-condition"); 5765 5766 size_t hr_used = hr->used(); 5767 size_t hr_capacity = hr->capacity(); 5768 size_t hr_pre_used = 0; 5769 _humongous_set.remove_with_proxy(hr, humongous_proxy_set); 5770 // We need to read this before we make the region non-humongous, 5771 // otherwise the information will be gone. 5772 uint last_index = hr->last_hc_index(); 5773 hr->set_notHumongous(); 5774 free_region(hr, &hr_pre_used, free_list, par); 5775 5776 uint i = hr->hrs_index() + 1; 5777 while (i < last_index) { 5778 HeapRegion* curr_hr = region_at(i); 5779 assert(curr_hr->continuesHumongous(), "invariant"); 5780 curr_hr->set_notHumongous(); 5781 free_region(curr_hr, &hr_pre_used, free_list, par); 5782 i += 1; 5783 } 5784 assert(hr_pre_used == hr_used, 5785 err_msg("hr_pre_used: "SIZE_FORMAT" and hr_used: "SIZE_FORMAT" " 5786 "should be the same", hr_pre_used, hr_used)); 5787 *pre_used += hr_pre_used; 5788 } 5789 5790 void G1CollectedHeap::update_sets_after_freeing_regions(size_t pre_used, 5791 FreeRegionList* free_list, 5792 OldRegionSet* old_proxy_set, 5793 HumongousRegionSet* humongous_proxy_set, 5794 bool par) { 5795 if (pre_used > 0) { 5796 Mutex* lock = (par) ? ParGCRareEvent_lock : NULL; 5797 MutexLockerEx x(lock, Mutex::_no_safepoint_check_flag); 5798 assert(_summary_bytes_used >= pre_used, 5799 err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" " 5800 "should be >= pre_used: "SIZE_FORMAT, 5801 _summary_bytes_used, pre_used)); 5802 _summary_bytes_used -= pre_used; 5803 } 5804 if (free_list != NULL && !free_list->is_empty()) { 5805 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag); 5806 _free_list.add_as_head(free_list); 5807 } 5808 if (old_proxy_set != NULL && !old_proxy_set->is_empty()) { 5809 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 5810 _old_set.update_from_proxy(old_proxy_set); 5811 } 5812 if (humongous_proxy_set != NULL && !humongous_proxy_set->is_empty()) { 5813 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 5814 _humongous_set.update_from_proxy(humongous_proxy_set); 5815 } 5816 } 5817 5818 class G1ParCleanupCTTask : public AbstractGangTask { 5819 CardTableModRefBS* _ct_bs; 5820 G1CollectedHeap* _g1h; 5821 HeapRegion* volatile _su_head; 5822 public: 5823 G1ParCleanupCTTask(CardTableModRefBS* ct_bs, 5824 G1CollectedHeap* g1h) : 5825 AbstractGangTask("G1 Par Cleanup CT Task"), 5826 _ct_bs(ct_bs), _g1h(g1h) { } 5827 5828 void work(uint worker_id) { 5829 HeapRegion* r; 5830 while (r = _g1h->pop_dirty_cards_region()) { 5831 clear_cards(r); 5832 } 5833 } 5834 5835 void clear_cards(HeapRegion* r) { 5836 // Cards of the survivors should have already been dirtied. 5837 if (!r->is_survivor()) { 5838 _ct_bs->clear(MemRegion(r->bottom(), r->end())); 5839 } 5840 } 5841 }; 5842 5843 #ifndef PRODUCT 5844 class G1VerifyCardTableCleanup: public HeapRegionClosure { 5845 G1CollectedHeap* _g1h; 5846 CardTableModRefBS* _ct_bs; 5847 public: 5848 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, CardTableModRefBS* ct_bs) 5849 : _g1h(g1h), _ct_bs(ct_bs) { } 5850 virtual bool doHeapRegion(HeapRegion* r) { 5851 if (r->is_survivor()) { 5852 _g1h->verify_dirty_region(r); 5853 } else { 5854 _g1h->verify_not_dirty_region(r); 5855 } 5856 return false; 5857 } 5858 }; 5859 5860 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) { 5861 // All of the region should be clean. 5862 CardTableModRefBS* ct_bs = (CardTableModRefBS*)barrier_set(); 5863 MemRegion mr(hr->bottom(), hr->end()); 5864 ct_bs->verify_not_dirty_region(mr); 5865 } 5866 5867 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) { 5868 // We cannot guarantee that [bottom(),end()] is dirty. Threads 5869 // dirty allocated blocks as they allocate them. The thread that 5870 // retires each region and replaces it with a new one will do a 5871 // maximal allocation to fill in [pre_dummy_top(),end()] but will 5872 // not dirty that area (one less thing to have to do while holding 5873 // a lock). So we can only verify that [bottom(),pre_dummy_top()] 5874 // is dirty. 5875 CardTableModRefBS* ct_bs = (CardTableModRefBS*) barrier_set(); 5876 MemRegion mr(hr->bottom(), hr->pre_dummy_top()); 5877 ct_bs->verify_dirty_region(mr); 5878 } 5879 5880 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) { 5881 CardTableModRefBS* ct_bs = (CardTableModRefBS*) barrier_set(); 5882 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) { 5883 verify_dirty_region(hr); 5884 } 5885 } 5886 5887 void G1CollectedHeap::verify_dirty_young_regions() { 5888 verify_dirty_young_list(_young_list->first_region()); 5889 } 5890 #endif 5891 5892 void G1CollectedHeap::cleanUpCardTable() { 5893 CardTableModRefBS* ct_bs = (CardTableModRefBS*) (barrier_set()); 5894 double start = os::elapsedTime(); 5895 5896 { 5897 // Iterate over the dirty cards region list. 5898 G1ParCleanupCTTask cleanup_task(ct_bs, this); 5899 5900 if (G1CollectedHeap::use_parallel_gc_threads()) { 5901 set_par_threads(); 5902 workers()->run_task(&cleanup_task); 5903 set_par_threads(0); 5904 } else { 5905 while (_dirty_cards_region_list) { 5906 HeapRegion* r = _dirty_cards_region_list; 5907 cleanup_task.clear_cards(r); 5908 _dirty_cards_region_list = r->get_next_dirty_cards_region(); 5909 if (_dirty_cards_region_list == r) { 5910 // The last region. 5911 _dirty_cards_region_list = NULL; 5912 } 5913 r->set_next_dirty_cards_region(NULL); 5914 } 5915 } 5916 #ifndef PRODUCT 5917 if (G1VerifyCTCleanup || VerifyAfterGC) { 5918 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs); 5919 heap_region_iterate(&cleanup_verifier); 5920 } 5921 #endif 5922 } 5923 5924 double elapsed = os::elapsedTime() - start; 5925 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0); 5926 } 5927 5928 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head) { 5929 size_t pre_used = 0; 5930 FreeRegionList local_free_list("Local List for CSet Freeing"); 5931 5932 double young_time_ms = 0.0; 5933 double non_young_time_ms = 0.0; 5934 5935 // Since the collection set is a superset of the the young list, 5936 // all we need to do to clear the young list is clear its 5937 // head and length, and unlink any young regions in the code below 5938 _young_list->clear(); 5939 5940 G1CollectorPolicy* policy = g1_policy(); 5941 5942 double start_sec = os::elapsedTime(); 5943 bool non_young = true; 5944 5945 HeapRegion* cur = cs_head; 5946 int age_bound = -1; 5947 size_t rs_lengths = 0; 5948 5949 while (cur != NULL) { 5950 assert(!is_on_master_free_list(cur), "sanity"); 5951 if (non_young) { 5952 if (cur->is_young()) { 5953 double end_sec = os::elapsedTime(); 5954 double elapsed_ms = (end_sec - start_sec) * 1000.0; 5955 non_young_time_ms += elapsed_ms; 5956 5957 start_sec = os::elapsedTime(); 5958 non_young = false; 5959 } 5960 } else { 5961 if (!cur->is_young()) { 5962 double end_sec = os::elapsedTime(); 5963 double elapsed_ms = (end_sec - start_sec) * 1000.0; 5964 young_time_ms += elapsed_ms; 5965 5966 start_sec = os::elapsedTime(); 5967 non_young = true; 5968 } 5969 } 5970 5971 rs_lengths += cur->rem_set()->occupied(); 5972 5973 HeapRegion* next = cur->next_in_collection_set(); 5974 assert(cur->in_collection_set(), "bad CS"); 5975 cur->set_next_in_collection_set(NULL); 5976 cur->set_in_collection_set(false); 5977 5978 if (cur->is_young()) { 5979 int index = cur->young_index_in_cset(); 5980 assert(index != -1, "invariant"); 5981 assert((uint) index < policy->young_cset_region_length(), "invariant"); 5982 size_t words_survived = _surviving_young_words[index]; 5983 cur->record_surv_words_in_group(words_survived); 5984 5985 // At this point the we have 'popped' cur from the collection set 5986 // (linked via next_in_collection_set()) but it is still in the 5987 // young list (linked via next_young_region()). Clear the 5988 // _next_young_region field. 5989 cur->set_next_young_region(NULL); 5990 } else { 5991 int index = cur->young_index_in_cset(); 5992 assert(index == -1, "invariant"); 5993 } 5994 5995 assert( (cur->is_young() && cur->young_index_in_cset() > -1) || 5996 (!cur->is_young() && cur->young_index_in_cset() == -1), 5997 "invariant" ); 5998 5999 if (!cur->evacuation_failed()) { 6000 MemRegion used_mr = cur->used_region(); 6001 6002 // And the region is empty. 6003 assert(!used_mr.is_empty(), "Should not have empty regions in a CS."); 6004 free_region(cur, &pre_used, &local_free_list, false /* par */); 6005 } else { 6006 cur->uninstall_surv_rate_group(); 6007 if (cur->is_young()) { 6008 cur->set_young_index_in_cset(-1); 6009 } 6010 cur->set_not_young(); 6011 cur->set_evacuation_failed(false); 6012 // The region is now considered to be old. 6013 _old_set.add(cur); 6014 } 6015 cur = next; 6016 } 6017 6018 policy->record_max_rs_lengths(rs_lengths); 6019 policy->cset_regions_freed(); 6020 6021 double end_sec = os::elapsedTime(); 6022 double elapsed_ms = (end_sec - start_sec) * 1000.0; 6023 6024 if (non_young) { 6025 non_young_time_ms += elapsed_ms; 6026 } else { 6027 young_time_ms += elapsed_ms; 6028 } 6029 6030 update_sets_after_freeing_regions(pre_used, &local_free_list, 6031 NULL /* old_proxy_set */, 6032 NULL /* humongous_proxy_set */, 6033 false /* par */); 6034 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms); 6035 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms); 6036 } 6037 6038 // This routine is similar to the above but does not record 6039 // any policy statistics or update free lists; we are abandoning 6040 // the current incremental collection set in preparation of a 6041 // full collection. After the full GC we will start to build up 6042 // the incremental collection set again. 6043 // This is only called when we're doing a full collection 6044 // and is immediately followed by the tearing down of the young list. 6045 6046 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) { 6047 HeapRegion* cur = cs_head; 6048 6049 while (cur != NULL) { 6050 HeapRegion* next = cur->next_in_collection_set(); 6051 assert(cur->in_collection_set(), "bad CS"); 6052 cur->set_next_in_collection_set(NULL); 6053 cur->set_in_collection_set(false); 6054 cur->set_young_index_in_cset(-1); 6055 cur = next; 6056 } 6057 } 6058 6059 void G1CollectedHeap::set_free_regions_coming() { 6060 if (G1ConcRegionFreeingVerbose) { 6061 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " 6062 "setting free regions coming"); 6063 } 6064 6065 assert(!free_regions_coming(), "pre-condition"); 6066 _free_regions_coming = true; 6067 } 6068 6069 void G1CollectedHeap::reset_free_regions_coming() { 6070 assert(free_regions_coming(), "pre-condition"); 6071 6072 { 6073 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6074 _free_regions_coming = false; 6075 SecondaryFreeList_lock->notify_all(); 6076 } 6077 6078 if (G1ConcRegionFreeingVerbose) { 6079 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " 6080 "reset free regions coming"); 6081 } 6082 } 6083 6084 void G1CollectedHeap::wait_while_free_regions_coming() { 6085 // Most of the time we won't have to wait, so let's do a quick test 6086 // first before we take the lock. 6087 if (!free_regions_coming()) { 6088 return; 6089 } 6090 6091 if (G1ConcRegionFreeingVerbose) { 6092 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " 6093 "waiting for free regions"); 6094 } 6095 6096 { 6097 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6098 while (free_regions_coming()) { 6099 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 6100 } 6101 } 6102 6103 if (G1ConcRegionFreeingVerbose) { 6104 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " 6105 "done waiting for free regions"); 6106 } 6107 } 6108 6109 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 6110 assert(heap_lock_held_for_gc(), 6111 "the heap lock should already be held by or for this thread"); 6112 _young_list->push_region(hr); 6113 } 6114 6115 class NoYoungRegionsClosure: public HeapRegionClosure { 6116 private: 6117 bool _success; 6118 public: 6119 NoYoungRegionsClosure() : _success(true) { } 6120 bool doHeapRegion(HeapRegion* r) { 6121 if (r->is_young()) { 6122 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young", 6123 r->bottom(), r->end()); 6124 _success = false; 6125 } 6126 return false; 6127 } 6128 bool success() { return _success; } 6129 }; 6130 6131 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) { 6132 bool ret = _young_list->check_list_empty(check_sample); 6133 6134 if (check_heap) { 6135 NoYoungRegionsClosure closure; 6136 heap_region_iterate(&closure); 6137 ret = ret && closure.success(); 6138 } 6139 6140 return ret; 6141 } 6142 6143 class TearDownRegionSetsClosure : public HeapRegionClosure { 6144 private: 6145 OldRegionSet *_old_set; 6146 6147 public: 6148 TearDownRegionSetsClosure(OldRegionSet* old_set) : _old_set(old_set) { } 6149 6150 bool doHeapRegion(HeapRegion* r) { 6151 if (r->is_empty()) { 6152 // We ignore empty regions, we'll empty the free list afterwards 6153 } else if (r->is_young()) { 6154 // We ignore young regions, we'll empty the young list afterwards 6155 } else if (r->isHumongous()) { 6156 // We ignore humongous regions, we're not tearing down the 6157 // humongous region set 6158 } else { 6159 // The rest should be old 6160 _old_set->remove(r); 6161 } 6162 return false; 6163 } 6164 6165 ~TearDownRegionSetsClosure() { 6166 assert(_old_set->is_empty(), "post-condition"); 6167 } 6168 }; 6169 6170 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) { 6171 assert_at_safepoint(true /* should_be_vm_thread */); 6172 6173 if (!free_list_only) { 6174 TearDownRegionSetsClosure cl(&_old_set); 6175 heap_region_iterate(&cl); 6176 6177 // Need to do this after the heap iteration to be able to 6178 // recognize the young regions and ignore them during the iteration. 6179 _young_list->empty_list(); 6180 } 6181 _free_list.remove_all(); 6182 } 6183 6184 class RebuildRegionSetsClosure : public HeapRegionClosure { 6185 private: 6186 bool _free_list_only; 6187 OldRegionSet* _old_set; 6188 FreeRegionList* _free_list; 6189 size_t _total_used; 6190 6191 public: 6192 RebuildRegionSetsClosure(bool free_list_only, 6193 OldRegionSet* old_set, FreeRegionList* free_list) : 6194 _free_list_only(free_list_only), 6195 _old_set(old_set), _free_list(free_list), _total_used(0) { 6196 assert(_free_list->is_empty(), "pre-condition"); 6197 if (!free_list_only) { 6198 assert(_old_set->is_empty(), "pre-condition"); 6199 } 6200 } 6201 6202 bool doHeapRegion(HeapRegion* r) { 6203 if (r->continuesHumongous()) { 6204 return false; 6205 } 6206 6207 if (r->is_empty()) { 6208 // Add free regions to the free list 6209 _free_list->add_as_tail(r); 6210 } else if (!_free_list_only) { 6211 assert(!r->is_young(), "we should not come across young regions"); 6212 6213 if (r->isHumongous()) { 6214 // We ignore humongous regions, we left the humongous set unchanged 6215 } else { 6216 // The rest should be old, add them to the old set 6217 _old_set->add(r); 6218 } 6219 _total_used += r->used(); 6220 } 6221 6222 return false; 6223 } 6224 6225 size_t total_used() { 6226 return _total_used; 6227 } 6228 }; 6229 6230 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { 6231 assert_at_safepoint(true /* should_be_vm_thread */); 6232 6233 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_free_list); 6234 heap_region_iterate(&cl); 6235 6236 if (!free_list_only) { 6237 _summary_bytes_used = cl.total_used(); 6238 } 6239 assert(_summary_bytes_used == recalculate_used(), 6240 err_msg("inconsistent _summary_bytes_used, " 6241 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT, 6242 _summary_bytes_used, recalculate_used())); 6243 } 6244 6245 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) { 6246 _refine_cte_cl->set_concurrent(concurrent); 6247 } 6248 6249 bool G1CollectedHeap::is_in_closed_subset(const void* p) const { 6250 HeapRegion* hr = heap_region_containing(p); 6251 if (hr == NULL) { 6252 return false; 6253 } else { 6254 return hr->is_in(p); 6255 } 6256 } 6257 6258 // Methods for the mutator alloc region 6259 6260 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 6261 bool force) { 6262 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6263 assert(!force || g1_policy()->can_expand_young_list(), 6264 "if force is true we should be able to expand the young list"); 6265 bool young_list_full = g1_policy()->is_young_list_full(); 6266 if (force || !young_list_full) { 6267 HeapRegion* new_alloc_region = new_region(word_size, 6268 false /* do_expand */); 6269 if (new_alloc_region != NULL) { 6270 set_region_short_lived_locked(new_alloc_region); 6271 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full); 6272 return new_alloc_region; 6273 } 6274 } 6275 return NULL; 6276 } 6277 6278 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 6279 size_t allocated_bytes) { 6280 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6281 assert(alloc_region->is_young(), "all mutator alloc regions should be young"); 6282 6283 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region); 6284 _summary_bytes_used += allocated_bytes; 6285 _hr_printer.retire(alloc_region); 6286 // We update the eden sizes here, when the region is retired, 6287 // instead of when it's allocated, since this is the point that its 6288 // used space has been recored in _summary_bytes_used. 6289 g1mm()->update_eden_size(); 6290 } 6291 6292 HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size, 6293 bool force) { 6294 return _g1h->new_mutator_alloc_region(word_size, force); 6295 } 6296 6297 void G1CollectedHeap::set_par_threads() { 6298 // Don't change the number of workers. Use the value previously set 6299 // in the workgroup. 6300 assert(G1CollectedHeap::use_parallel_gc_threads(), "shouldn't be here otherwise"); 6301 uint n_workers = workers()->active_workers(); 6302 assert(UseDynamicNumberOfGCThreads || 6303 n_workers == workers()->total_workers(), 6304 "Otherwise should be using the total number of workers"); 6305 if (n_workers == 0) { 6306 assert(false, "Should have been set in prior evacuation pause."); 6307 n_workers = ParallelGCThreads; 6308 workers()->set_active_workers(n_workers); 6309 } 6310 set_par_threads(n_workers); 6311 } 6312 6313 void MutatorAllocRegion::retire_region(HeapRegion* alloc_region, 6314 size_t allocated_bytes) { 6315 _g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes); 6316 } 6317 6318 // Methods for the GC alloc regions 6319 6320 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, 6321 uint count, 6322 GCAllocPurpose ap) { 6323 assert(FreeList_lock->owned_by_self(), "pre-condition"); 6324 6325 if (count < g1_policy()->max_regions(ap)) { 6326 HeapRegion* new_alloc_region = new_region(word_size, 6327 true /* do_expand */); 6328 if (new_alloc_region != NULL) { 6329 // We really only need to do this for old regions given that we 6330 // should never scan survivors. But it doesn't hurt to do it 6331 // for survivors too. 6332 new_alloc_region->set_saved_mark(); 6333 if (ap == GCAllocForSurvived) { 6334 new_alloc_region->set_survivor(); 6335 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor); 6336 } else { 6337 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old); 6338 } 6339 bool during_im = g1_policy()->during_initial_mark_pause(); 6340 new_alloc_region->note_start_of_copying(during_im); 6341 return new_alloc_region; 6342 } else { 6343 g1_policy()->note_alloc_region_limit_reached(ap); 6344 } 6345 } 6346 return NULL; 6347 } 6348 6349 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 6350 size_t allocated_bytes, 6351 GCAllocPurpose ap) { 6352 bool during_im = g1_policy()->during_initial_mark_pause(); 6353 alloc_region->note_end_of_copying(during_im); 6354 g1_policy()->record_bytes_copied_during_gc(allocated_bytes); 6355 if (ap == GCAllocForSurvived) { 6356 young_list()->add_survivor_region(alloc_region); 6357 } else { 6358 _old_set.add(alloc_region); 6359 } 6360 _hr_printer.retire(alloc_region); 6361 } 6362 6363 HeapRegion* SurvivorGCAllocRegion::allocate_new_region(size_t word_size, 6364 bool force) { 6365 assert(!force, "not supported for GC alloc regions"); 6366 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForSurvived); 6367 } 6368 6369 void SurvivorGCAllocRegion::retire_region(HeapRegion* alloc_region, 6370 size_t allocated_bytes) { 6371 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes, 6372 GCAllocForSurvived); 6373 } 6374 6375 HeapRegion* OldGCAllocRegion::allocate_new_region(size_t word_size, 6376 bool force) { 6377 assert(!force, "not supported for GC alloc regions"); 6378 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForTenured); 6379 } 6380 6381 void OldGCAllocRegion::retire_region(HeapRegion* alloc_region, 6382 size_t allocated_bytes) { 6383 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes, 6384 GCAllocForTenured); 6385 } 6386 // Heap region set verification 6387 6388 class VerifyRegionListsClosure : public HeapRegionClosure { 6389 private: 6390 FreeRegionList* _free_list; 6391 OldRegionSet* _old_set; 6392 HumongousRegionSet* _humongous_set; 6393 uint _region_count; 6394 6395 public: 6396 VerifyRegionListsClosure(OldRegionSet* old_set, 6397 HumongousRegionSet* humongous_set, 6398 FreeRegionList* free_list) : 6399 _old_set(old_set), _humongous_set(humongous_set), 6400 _free_list(free_list), _region_count(0) { } 6401 6402 uint region_count() { return _region_count; } 6403 6404 bool doHeapRegion(HeapRegion* hr) { 6405 _region_count += 1; 6406 6407 if (hr->continuesHumongous()) { 6408 return false; 6409 } 6410 6411 if (hr->is_young()) { 6412 // TODO 6413 } else if (hr->startsHumongous()) { 6414 _humongous_set->verify_next_region(hr); 6415 } else if (hr->is_empty()) { 6416 _free_list->verify_next_region(hr); 6417 } else { 6418 _old_set->verify_next_region(hr); 6419 } 6420 return false; 6421 } 6422 }; 6423 6424 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index, 6425 HeapWord* bottom) { 6426 HeapWord* end = bottom + HeapRegion::GrainWords; 6427 MemRegion mr(bottom, end); 6428 assert(_g1_reserved.contains(mr), "invariant"); 6429 // This might return NULL if the allocation fails 6430 return new HeapRegion(hrs_index, _bot_shared, mr); 6431 } 6432 6433 void G1CollectedHeap::verify_region_sets() { 6434 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6435 6436 // First, check the explicit lists. 6437 _free_list.verify(); 6438 { 6439 // Given that a concurrent operation might be adding regions to 6440 // the secondary free list we have to take the lock before 6441 // verifying it. 6442 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6443 _secondary_free_list.verify(); 6444 } 6445 _old_set.verify(); 6446 _humongous_set.verify(); 6447 6448 // If a concurrent region freeing operation is in progress it will 6449 // be difficult to correctly attributed any free regions we come 6450 // across to the correct free list given that they might belong to 6451 // one of several (free_list, secondary_free_list, any local lists, 6452 // etc.). So, if that's the case we will skip the rest of the 6453 // verification operation. Alternatively, waiting for the concurrent 6454 // operation to complete will have a non-trivial effect on the GC's 6455 // operation (no concurrent operation will last longer than the 6456 // interval between two calls to verification) and it might hide 6457 // any issues that we would like to catch during testing. 6458 if (free_regions_coming()) { 6459 return; 6460 } 6461 6462 // Make sure we append the secondary_free_list on the free_list so 6463 // that all free regions we will come across can be safely 6464 // attributed to the free_list. 6465 append_secondary_free_list_if_not_empty_with_lock(); 6466 6467 // Finally, make sure that the region accounting in the lists is 6468 // consistent with what we see in the heap. 6469 _old_set.verify_start(); 6470 _humongous_set.verify_start(); 6471 _free_list.verify_start(); 6472 6473 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_free_list); 6474 heap_region_iterate(&cl); 6475 6476 _old_set.verify_end(); 6477 _humongous_set.verify_end(); 6478 _free_list.verify_end(); 6479 }