1 /* 2 * Copyright (c) 2001, 2014, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #if !defined(__clang_major__) && defined(__GNUC__) 26 // FIXME, formats have issues. Disable this macro definition, compile, and study warnings for more information. 27 #define ATTRIBUTE_PRINTF(x,y) 28 #endif 29 30 #include "precompiled.hpp" 31 #include "classfile/stringTable.hpp" 32 #include "code/codeCache.hpp" 33 #include "code/icBuffer.hpp" 34 #include "gc_implementation/g1/bufferingOopClosure.hpp" 35 #include "gc_implementation/g1/concurrentG1Refine.hpp" 36 #include "gc_implementation/g1/concurrentG1RefineThread.hpp" 37 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp" 38 #include "gc_implementation/g1/g1AllocRegion.inline.hpp" 39 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp" 40 #include "gc_implementation/g1/g1CollectorPolicy.hpp" 41 #include "gc_implementation/g1/g1ErgoVerbose.hpp" 42 #include "gc_implementation/g1/g1EvacFailure.hpp" 43 #include "gc_implementation/g1/g1GCPhaseTimes.hpp" 44 #include "gc_implementation/g1/g1Log.hpp" 45 #include "gc_implementation/g1/g1MarkSweep.hpp" 46 #include "gc_implementation/g1/g1OopClosures.inline.hpp" 47 #include "gc_implementation/g1/g1ParScanThreadState.inline.hpp" 48 #include "gc_implementation/g1/g1RemSet.inline.hpp" 49 #include "gc_implementation/g1/g1StringDedup.hpp" 50 #include "gc_implementation/g1/g1YCTypes.hpp" 51 #include "gc_implementation/g1/heapRegion.inline.hpp" 52 #include "gc_implementation/g1/heapRegionRemSet.hpp" 53 #include "gc_implementation/g1/heapRegionSeq.inline.hpp" 54 #include "gc_implementation/g1/vm_operations_g1.hpp" 55 #include "gc_implementation/shared/gcHeapSummary.hpp" 56 #include "gc_implementation/shared/gcTimer.hpp" 57 #include "gc_implementation/shared/gcTrace.hpp" 58 #include "gc_implementation/shared/gcTraceTime.hpp" 59 #include "gc_implementation/shared/isGCActiveMark.hpp" 60 #include "memory/gcLocker.inline.hpp" 61 #include "memory/generationSpec.hpp" 62 #include "memory/iterator.hpp" 63 #include "memory/referenceProcessor.hpp" 64 #include "oops/oop.inline.hpp" 65 #include "oops/oop.pcgc.inline.hpp" 66 #include "runtime/atomic.inline.hpp" 67 #include "runtime/orderAccess.inline.hpp" 68 #include "runtime/vmThread.hpp" 69 #include "utilities/globalDefinitions.hpp" 70 71 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0; 72 73 // turn it on so that the contents of the young list (scan-only / 74 // to-be-collected) are printed at "strategic" points before / during 75 // / after the collection --- this is useful for debugging 76 #define YOUNG_LIST_VERBOSE 0 77 // CURRENT STATUS 78 // This file is under construction. Search for "FIXME". 79 80 // INVARIANTS/NOTES 81 // 82 // All allocation activity covered by the G1CollectedHeap interface is 83 // serialized by acquiring the HeapLock. This happens in mem_allocate 84 // and allocate_new_tlab, which are the "entry" points to the 85 // allocation code from the rest of the JVM. (Note that this does not 86 // apply to TLAB allocation, which is not part of this interface: it 87 // is done by clients of this interface.) 88 89 // Notes on implementation of parallelism in different tasks. 90 // 91 // G1ParVerifyTask uses heap_region_par_iterate_chunked() for parallelism. 92 // The number of GC workers is passed to heap_region_par_iterate_chunked(). 93 // It does use run_task() which sets _n_workers in the task. 94 // G1ParTask executes g1_process_strong_roots() -> 95 // SharedHeap::process_strong_roots() which calls eventually to 96 // CardTableModRefBS::par_non_clean_card_iterate_work() which uses 97 // SequentialSubTasksDone. SharedHeap::process_strong_roots() also 98 // directly uses SubTasksDone (_process_strong_tasks field in SharedHeap). 99 // 100 101 // Local to this file. 102 103 class RefineCardTableEntryClosure: public CardTableEntryClosure { 104 bool _concurrent; 105 public: 106 RefineCardTableEntryClosure() : _concurrent(true) { } 107 108 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 109 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false); 110 // This path is executed by the concurrent refine or mutator threads, 111 // concurrently, and so we do not care if card_ptr contains references 112 // that point into the collection set. 113 assert(!oops_into_cset, "should be"); 114 115 if (_concurrent && SuspendibleThreadSet::should_yield()) { 116 // Caller will actually yield. 117 return false; 118 } 119 // Otherwise, we finished successfully; return true. 120 return true; 121 } 122 123 void set_concurrent(bool b) { _concurrent = b; } 124 }; 125 126 127 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure { 128 size_t _num_processed; 129 CardTableModRefBS* _ctbs; 130 int _histo[256]; 131 132 public: 133 ClearLoggedCardTableEntryClosure() : 134 _num_processed(0), _ctbs(G1CollectedHeap::heap()->g1_barrier_set()) 135 { 136 for (int i = 0; i < 256; i++) _histo[i] = 0; 137 } 138 139 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 140 unsigned char* ujb = (unsigned char*)card_ptr; 141 int ind = (int)(*ujb); 142 _histo[ind]++; 143 144 *card_ptr = (jbyte)CardTableModRefBS::clean_card_val(); 145 _num_processed++; 146 147 return true; 148 } 149 150 size_t num_processed() { return _num_processed; } 151 152 void print_histo() { 153 gclog_or_tty->print_cr("Card table value histogram:"); 154 for (int i = 0; i < 256; i++) { 155 if (_histo[i] != 0) { 156 gclog_or_tty->print_cr(" %d: %d", i, _histo[i]); 157 } 158 } 159 } 160 }; 161 162 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure { 163 private: 164 size_t _num_processed; 165 166 public: 167 RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { } 168 169 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 170 *card_ptr = CardTableModRefBS::dirty_card_val(); 171 _num_processed++; 172 return true; 173 } 174 175 size_t num_processed() const { return _num_processed; } 176 }; 177 178 YoungList::YoungList(G1CollectedHeap* g1h) : 179 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0), 180 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) { 181 guarantee(check_list_empty(false), "just making sure..."); 182 } 183 184 void YoungList::push_region(HeapRegion *hr) { 185 assert(!hr->is_young(), "should not already be young"); 186 assert(hr->get_next_young_region() == NULL, "cause it should!"); 187 188 hr->set_next_young_region(_head); 189 _head = hr; 190 191 _g1h->g1_policy()->set_region_eden(hr, (int) _length); 192 ++_length; 193 } 194 195 void YoungList::add_survivor_region(HeapRegion* hr) { 196 assert(hr->is_survivor(), "should be flagged as survivor region"); 197 assert(hr->get_next_young_region() == NULL, "cause it should!"); 198 199 hr->set_next_young_region(_survivor_head); 200 if (_survivor_head == NULL) { 201 _survivor_tail = hr; 202 } 203 _survivor_head = hr; 204 ++_survivor_length; 205 } 206 207 void YoungList::empty_list(HeapRegion* list) { 208 while (list != NULL) { 209 HeapRegion* next = list->get_next_young_region(); 210 list->set_next_young_region(NULL); 211 list->uninstall_surv_rate_group(); 212 list->set_not_young(); 213 list = next; 214 } 215 } 216 217 void YoungList::empty_list() { 218 assert(check_list_well_formed(), "young list should be well formed"); 219 220 empty_list(_head); 221 _head = NULL; 222 _length = 0; 223 224 empty_list(_survivor_head); 225 _survivor_head = NULL; 226 _survivor_tail = NULL; 227 _survivor_length = 0; 228 229 _last_sampled_rs_lengths = 0; 230 231 assert(check_list_empty(false), "just making sure..."); 232 } 233 234 bool YoungList::check_list_well_formed() { 235 bool ret = true; 236 237 uint length = 0; 238 HeapRegion* curr = _head; 239 HeapRegion* last = NULL; 240 while (curr != NULL) { 241 if (!curr->is_young()) { 242 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" " 243 "incorrectly tagged (y: %d, surv: %d)", 244 curr->bottom(), curr->end(), 245 curr->is_young(), curr->is_survivor()); 246 ret = false; 247 } 248 ++length; 249 last = curr; 250 curr = curr->get_next_young_region(); 251 } 252 ret = ret && (length == _length); 253 254 if (!ret) { 255 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!"); 256 gclog_or_tty->print_cr("### list has %u entries, _length is %u", 257 length, _length); 258 } 259 260 return ret; 261 } 262 263 bool YoungList::check_list_empty(bool check_sample) { 264 bool ret = true; 265 266 if (_length != 0) { 267 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u", 268 _length); 269 ret = false; 270 } 271 if (check_sample && _last_sampled_rs_lengths != 0) { 272 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths"); 273 ret = false; 274 } 275 if (_head != NULL) { 276 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head"); 277 ret = false; 278 } 279 if (!ret) { 280 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty"); 281 } 282 283 return ret; 284 } 285 286 void 287 YoungList::rs_length_sampling_init() { 288 _sampled_rs_lengths = 0; 289 _curr = _head; 290 } 291 292 bool 293 YoungList::rs_length_sampling_more() { 294 return _curr != NULL; 295 } 296 297 void 298 YoungList::rs_length_sampling_next() { 299 assert( _curr != NULL, "invariant" ); 300 size_t rs_length = _curr->rem_set()->occupied(); 301 302 _sampled_rs_lengths += rs_length; 303 304 // The current region may not yet have been added to the 305 // incremental collection set (it gets added when it is 306 // retired as the current allocation region). 307 if (_curr->in_collection_set()) { 308 // Update the collection set policy information for this region 309 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length); 310 } 311 312 _curr = _curr->get_next_young_region(); 313 if (_curr == NULL) { 314 _last_sampled_rs_lengths = _sampled_rs_lengths; 315 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths); 316 } 317 } 318 319 void 320 YoungList::reset_auxilary_lists() { 321 guarantee( is_empty(), "young list should be empty" ); 322 assert(check_list_well_formed(), "young list should be well formed"); 323 324 // Add survivor regions to SurvRateGroup. 325 _g1h->g1_policy()->note_start_adding_survivor_regions(); 326 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */); 327 328 int young_index_in_cset = 0; 329 for (HeapRegion* curr = _survivor_head; 330 curr != NULL; 331 curr = curr->get_next_young_region()) { 332 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset); 333 334 // The region is a non-empty survivor so let's add it to 335 // the incremental collection set for the next evacuation 336 // pause. 337 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr); 338 young_index_in_cset += 1; 339 } 340 assert((uint) young_index_in_cset == _survivor_length, "post-condition"); 341 _g1h->g1_policy()->note_stop_adding_survivor_regions(); 342 343 _head = _survivor_head; 344 _length = _survivor_length; 345 if (_survivor_head != NULL) { 346 assert(_survivor_tail != NULL, "cause it shouldn't be"); 347 assert(_survivor_length > 0, "invariant"); 348 _survivor_tail->set_next_young_region(NULL); 349 } 350 351 // Don't clear the survivor list handles until the start of 352 // the next evacuation pause - we need it in order to re-tag 353 // the survivor regions from this evacuation pause as 'young' 354 // at the start of the next. 355 356 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */); 357 358 assert(check_list_well_formed(), "young list should be well formed"); 359 } 360 361 void YoungList::print() { 362 HeapRegion* lists[] = {_head, _survivor_head}; 363 const char* names[] = {"YOUNG", "SURVIVOR"}; 364 365 for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) { 366 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]); 367 HeapRegion *curr = lists[list]; 368 if (curr == NULL) 369 gclog_or_tty->print_cr(" empty"); 370 while (curr != NULL) { 371 gclog_or_tty->print_cr(" "HR_FORMAT", P: "PTR_FORMAT "N: "PTR_FORMAT", age: %4d", 372 HR_FORMAT_PARAMS(curr), 373 curr->prev_top_at_mark_start(), 374 curr->next_top_at_mark_start(), 375 curr->age_in_surv_rate_group_cond()); 376 curr = curr->get_next_young_region(); 377 } 378 } 379 380 gclog_or_tty->cr(); 381 } 382 383 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr) 384 { 385 // Claim the right to put the region on the dirty cards region list 386 // by installing a self pointer. 387 HeapRegion* next = hr->get_next_dirty_cards_region(); 388 if (next == NULL) { 389 HeapRegion* res = (HeapRegion*) 390 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(), 391 NULL); 392 if (res == NULL) { 393 HeapRegion* head; 394 do { 395 // Put the region to the dirty cards region list. 396 head = _dirty_cards_region_list; 397 next = (HeapRegion*) 398 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head); 399 if (next == head) { 400 assert(hr->get_next_dirty_cards_region() == hr, 401 "hr->get_next_dirty_cards_region() != hr"); 402 if (next == NULL) { 403 // The last region in the list points to itself. 404 hr->set_next_dirty_cards_region(hr); 405 } else { 406 hr->set_next_dirty_cards_region(next); 407 } 408 } 409 } while (next != head); 410 } 411 } 412 } 413 414 HeapRegion* G1CollectedHeap::pop_dirty_cards_region() 415 { 416 HeapRegion* head; 417 HeapRegion* hr; 418 do { 419 head = _dirty_cards_region_list; 420 if (head == NULL) { 421 return NULL; 422 } 423 HeapRegion* new_head = head->get_next_dirty_cards_region(); 424 if (head == new_head) { 425 // The last region. 426 new_head = NULL; 427 } 428 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list, 429 head); 430 } while (hr != head); 431 assert(hr != NULL, "invariant"); 432 hr->set_next_dirty_cards_region(NULL); 433 return hr; 434 } 435 436 #ifdef ASSERT 437 // A region is added to the collection set as it is retired 438 // so an address p can point to a region which will be in the 439 // collection set but has not yet been retired. This method 440 // therefore is only accurate during a GC pause after all 441 // regions have been retired. It is used for debugging 442 // to check if an nmethod has references to objects that can 443 // be move during a partial collection. Though it can be 444 // inaccurate, it is sufficient for G1 because the conservative 445 // implementation of is_scavengable() for G1 will indicate that 446 // all nmethods must be scanned during a partial collection. 447 bool G1CollectedHeap::is_in_partial_collection(const void* p) { 448 if (p == NULL) { 449 return false; 450 } 451 return heap_region_containing(p)->in_collection_set(); 452 } 453 #endif 454 455 // Returns true if the reference points to an object that 456 // can move in an incremental collection. 457 bool G1CollectedHeap::is_scavengable(const void* p) { 458 HeapRegion* hr = heap_region_containing(p); 459 return !hr->isHumongous(); 460 } 461 462 void G1CollectedHeap::check_ct_logs_at_safepoint() { 463 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 464 CardTableModRefBS* ct_bs = g1_barrier_set(); 465 466 // Count the dirty cards at the start. 467 CountNonCleanMemRegionClosure count1(this); 468 ct_bs->mod_card_iterate(&count1); 469 int orig_count = count1.n(); 470 471 // First clear the logged cards. 472 ClearLoggedCardTableEntryClosure clear; 473 dcqs.apply_closure_to_all_completed_buffers(&clear); 474 dcqs.iterate_closure_all_threads(&clear, false); 475 clear.print_histo(); 476 477 // Now ensure that there's no dirty cards. 478 CountNonCleanMemRegionClosure count2(this); 479 ct_bs->mod_card_iterate(&count2); 480 if (count2.n() != 0) { 481 gclog_or_tty->print_cr("Card table has %d entries; %d originally", 482 count2.n(), orig_count); 483 } 484 guarantee(count2.n() == 0, "Card table should be clean."); 485 486 RedirtyLoggedCardTableEntryClosure redirty; 487 dcqs.apply_closure_to_all_completed_buffers(&redirty); 488 dcqs.iterate_closure_all_threads(&redirty, false); 489 gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.", 490 clear.num_processed(), orig_count); 491 guarantee(redirty.num_processed() == clear.num_processed(), 492 err_msg("Redirtied "SIZE_FORMAT" cards, bug cleared "SIZE_FORMAT, 493 redirty.num_processed(), clear.num_processed())); 494 495 CountNonCleanMemRegionClosure count3(this); 496 ct_bs->mod_card_iterate(&count3); 497 if (count3.n() != orig_count) { 498 gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.", 499 orig_count, count3.n()); 500 guarantee(count3.n() >= orig_count, "Should have restored them all."); 501 } 502 } 503 504 // Private class members. 505 506 G1CollectedHeap* G1CollectedHeap::_g1h; 507 508 // Private methods. 509 510 HeapRegion* 511 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) { 512 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 513 while (!_secondary_free_list.is_empty() || free_regions_coming()) { 514 if (!_secondary_free_list.is_empty()) { 515 if (G1ConcRegionFreeingVerbose) { 516 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 517 "secondary_free_list has %u entries", 518 _secondary_free_list.length()); 519 } 520 // It looks as if there are free regions available on the 521 // secondary_free_list. Let's move them to the free_list and try 522 // again to allocate from it. 523 append_secondary_free_list(); 524 525 assert(!_free_list.is_empty(), "if the secondary_free_list was not " 526 "empty we should have moved at least one entry to the free_list"); 527 HeapRegion* res = _free_list.remove_region(is_old); 528 if (G1ConcRegionFreeingVerbose) { 529 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 530 "allocated "HR_FORMAT" from secondary_free_list", 531 HR_FORMAT_PARAMS(res)); 532 } 533 return res; 534 } 535 536 // Wait here until we get notified either when (a) there are no 537 // more free regions coming or (b) some regions have been moved on 538 // the secondary_free_list. 539 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 540 } 541 542 if (G1ConcRegionFreeingVerbose) { 543 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 544 "could not allocate from secondary_free_list"); 545 } 546 return NULL; 547 } 548 549 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) { 550 assert(!isHumongous(word_size) || word_size <= HeapRegion::GrainWords, 551 "the only time we use this to allocate a humongous region is " 552 "when we are allocating a single humongous region"); 553 554 HeapRegion* res; 555 if (G1StressConcRegionFreeing) { 556 if (!_secondary_free_list.is_empty()) { 557 if (G1ConcRegionFreeingVerbose) { 558 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 559 "forced to look at the secondary_free_list"); 560 } 561 res = new_region_try_secondary_free_list(is_old); 562 if (res != NULL) { 563 return res; 564 } 565 } 566 } 567 568 res = _free_list.remove_region(is_old); 569 570 if (res == NULL) { 571 if (G1ConcRegionFreeingVerbose) { 572 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 573 "res == NULL, trying the secondary_free_list"); 574 } 575 res = new_region_try_secondary_free_list(is_old); 576 } 577 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) { 578 // Currently, only attempts to allocate GC alloc regions set 579 // do_expand to true. So, we should only reach here during a 580 // safepoint. If this assumption changes we might have to 581 // reconsider the use of _expand_heap_after_alloc_failure. 582 assert(SafepointSynchronize::is_at_safepoint(), "invariant"); 583 584 ergo_verbose1(ErgoHeapSizing, 585 "attempt heap expansion", 586 ergo_format_reason("region allocation request failed") 587 ergo_format_byte("allocation request"), 588 word_size * HeapWordSize); 589 if (expand(word_size * HeapWordSize)) { 590 // Given that expand() succeeded in expanding the heap, and we 591 // always expand the heap by an amount aligned to the heap 592 // region size, the free list should in theory not be empty. 593 // In either case remove_region() will check for NULL. 594 res = _free_list.remove_region(is_old); 595 } else { 596 _expand_heap_after_alloc_failure = false; 597 } 598 } 599 return res; 600 } 601 602 uint G1CollectedHeap::humongous_obj_allocate_find_first(uint num_regions, 603 size_t word_size) { 604 assert(isHumongous(word_size), "word_size should be humongous"); 605 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition"); 606 607 uint first = G1_NULL_HRS_INDEX; 608 if (num_regions == 1) { 609 // Only one region to allocate, no need to go through the slower 610 // path. The caller will attempt the expansion if this fails, so 611 // let's not try to expand here too. 612 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */); 613 if (hr != NULL) { 614 first = hr->hrs_index(); 615 } else { 616 first = G1_NULL_HRS_INDEX; 617 } 618 } else { 619 // We can't allocate humongous regions while cleanupComplete() is 620 // running, since some of the regions we find to be empty might not 621 // yet be added to the free list and it is not straightforward to 622 // know which list they are on so that we can remove them. Note 623 // that we only need to do this if we need to allocate more than 624 // one region to satisfy the current humongous allocation 625 // request. If we are only allocating one region we use the common 626 // region allocation code (see above). 627 wait_while_free_regions_coming(); 628 append_secondary_free_list_if_not_empty_with_lock(); 629 630 if (free_regions() >= num_regions) { 631 first = _hrs.find_contiguous(num_regions); 632 if (first != G1_NULL_HRS_INDEX) { 633 for (uint i = first; i < first + num_regions; ++i) { 634 HeapRegion* hr = region_at(i); 635 assert(hr->is_empty(), "sanity"); 636 assert(is_on_master_free_list(hr), "sanity"); 637 hr->set_pending_removal(true); 638 } 639 _free_list.remove_all_pending(num_regions); 640 } 641 } 642 } 643 return first; 644 } 645 646 HeapWord* 647 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first, 648 uint num_regions, 649 size_t word_size) { 650 assert(first != G1_NULL_HRS_INDEX, "pre-condition"); 651 assert(isHumongous(word_size), "word_size should be humongous"); 652 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition"); 653 654 // Index of last region in the series + 1. 655 uint last = first + num_regions; 656 657 // We need to initialize the region(s) we just discovered. This is 658 // a bit tricky given that it can happen concurrently with 659 // refinement threads refining cards on these regions and 660 // potentially wanting to refine the BOT as they are scanning 661 // those cards (this can happen shortly after a cleanup; see CR 662 // 6991377). So we have to set up the region(s) carefully and in 663 // a specific order. 664 665 // The word size sum of all the regions we will allocate. 666 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords; 667 assert(word_size <= word_size_sum, "sanity"); 668 669 // This will be the "starts humongous" region. 670 HeapRegion* first_hr = region_at(first); 671 // The header of the new object will be placed at the bottom of 672 // the first region. 673 HeapWord* new_obj = first_hr->bottom(); 674 // This will be the new end of the first region in the series that 675 // should also match the end of the last region in the series. 676 HeapWord* new_end = new_obj + word_size_sum; 677 // This will be the new top of the first region that will reflect 678 // this allocation. 679 HeapWord* new_top = new_obj + word_size; 680 681 // First, we need to zero the header of the space that we will be 682 // allocating. When we update top further down, some refinement 683 // threads might try to scan the region. By zeroing the header we 684 // ensure that any thread that will try to scan the region will 685 // come across the zero klass word and bail out. 686 // 687 // NOTE: It would not have been correct to have used 688 // CollectedHeap::fill_with_object() and make the space look like 689 // an int array. The thread that is doing the allocation will 690 // later update the object header to a potentially different array 691 // type and, for a very short period of time, the klass and length 692 // fields will be inconsistent. This could cause a refinement 693 // thread to calculate the object size incorrectly. 694 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0); 695 696 // We will set up the first region as "starts humongous". This 697 // will also update the BOT covering all the regions to reflect 698 // that there is a single object that starts at the bottom of the 699 // first region. 700 first_hr->set_startsHumongous(new_top, new_end); 701 702 // Then, if there are any, we will set up the "continues 703 // humongous" regions. 704 HeapRegion* hr = NULL; 705 for (uint i = first + 1; i < last; ++i) { 706 hr = region_at(i); 707 hr->set_continuesHumongous(first_hr); 708 } 709 // If we have "continues humongous" regions (hr != NULL), then the 710 // end of the last one should match new_end. 711 assert(hr == NULL || hr->end() == new_end, "sanity"); 712 713 // Up to this point no concurrent thread would have been able to 714 // do any scanning on any region in this series. All the top 715 // fields still point to bottom, so the intersection between 716 // [bottom,top] and [card_start,card_end] will be empty. Before we 717 // update the top fields, we'll do a storestore to make sure that 718 // no thread sees the update to top before the zeroing of the 719 // object header and the BOT initialization. 720 OrderAccess::storestore(); 721 722 // Now that the BOT and the object header have been initialized, 723 // we can update top of the "starts humongous" region. 724 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(), 725 "new_top should be in this region"); 726 first_hr->set_top(new_top); 727 if (_hr_printer.is_active()) { 728 HeapWord* bottom = first_hr->bottom(); 729 HeapWord* end = first_hr->orig_end(); 730 if ((first + 1) == last) { 731 // the series has a single humongous region 732 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top); 733 } else { 734 // the series has more than one humongous regions 735 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end); 736 } 737 } 738 739 // Now, we will update the top fields of the "continues humongous" 740 // regions. The reason we need to do this is that, otherwise, 741 // these regions would look empty and this will confuse parts of 742 // G1. For example, the code that looks for a consecutive number 743 // of empty regions will consider them empty and try to 744 // re-allocate them. We can extend is_empty() to also include 745 // !continuesHumongous(), but it is easier to just update the top 746 // fields here. The way we set top for all regions (i.e., top == 747 // end for all regions but the last one, top == new_top for the 748 // last one) is actually used when we will free up the humongous 749 // region in free_humongous_region(). 750 hr = NULL; 751 for (uint i = first + 1; i < last; ++i) { 752 hr = region_at(i); 753 if ((i + 1) == last) { 754 // last continues humongous region 755 assert(hr->bottom() < new_top && new_top <= hr->end(), 756 "new_top should fall on this region"); 757 hr->set_top(new_top); 758 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top); 759 } else { 760 // not last one 761 assert(new_top > hr->end(), "new_top should be above this region"); 762 hr->set_top(hr->end()); 763 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end()); 764 } 765 } 766 // If we have continues humongous regions (hr != NULL), then the 767 // end of the last one should match new_end and its top should 768 // match new_top. 769 assert(hr == NULL || 770 (hr->end() == new_end && hr->top() == new_top), "sanity"); 771 check_bitmaps("Humongous Region Allocation", first_hr); 772 773 assert(first_hr->used() == word_size * HeapWordSize, "invariant"); 774 _summary_bytes_used += first_hr->used(); 775 _humongous_set.add(first_hr); 776 777 return new_obj; 778 } 779 780 // If could fit into free regions w/o expansion, try. 781 // Otherwise, if can expand, do so. 782 // Otherwise, if using ex regions might help, try with ex given back. 783 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) { 784 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 785 786 verify_region_sets_optional(); 787 788 size_t word_size_rounded = round_to(word_size, HeapRegion::GrainWords); 789 uint num_regions = (uint) (word_size_rounded / HeapRegion::GrainWords); 790 uint x_num = expansion_regions(); 791 uint fs = _hrs.free_suffix(); 792 uint first = humongous_obj_allocate_find_first(num_regions, word_size); 793 if (first == G1_NULL_HRS_INDEX) { 794 // The only thing we can do now is attempt expansion. 795 if (fs + x_num >= num_regions) { 796 // If the number of regions we're trying to allocate for this 797 // object is at most the number of regions in the free suffix, 798 // then the call to humongous_obj_allocate_find_first() above 799 // should have succeeded and we wouldn't be here. 800 // 801 // We should only be trying to expand when the free suffix is 802 // not sufficient for the object _and_ we have some expansion 803 // room available. 804 assert(num_regions > fs, "earlier allocation should have succeeded"); 805 806 ergo_verbose1(ErgoHeapSizing, 807 "attempt heap expansion", 808 ergo_format_reason("humongous allocation request failed") 809 ergo_format_byte("allocation request"), 810 word_size * HeapWordSize); 811 if (expand((num_regions - fs) * HeapRegion::GrainBytes)) { 812 // Even though the heap was expanded, it might not have 813 // reached the desired size. So, we cannot assume that the 814 // allocation will succeed. 815 first = humongous_obj_allocate_find_first(num_regions, word_size); 816 } 817 } 818 } 819 820 HeapWord* result = NULL; 821 if (first != G1_NULL_HRS_INDEX) { 822 result = 823 humongous_obj_allocate_initialize_regions(first, num_regions, word_size); 824 assert(result != NULL, "it should always return a valid result"); 825 826 // A successful humongous object allocation changes the used space 827 // information of the old generation so we need to recalculate the 828 // sizes and update the jstat counters here. 829 g1mm()->update_sizes(); 830 } 831 832 verify_region_sets_optional(); 833 834 return result; 835 } 836 837 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) { 838 assert_heap_not_locked_and_not_at_safepoint(); 839 assert(!isHumongous(word_size), "we do not allow humongous TLABs"); 840 841 unsigned int dummy_gc_count_before; 842 int dummy_gclocker_retry_count = 0; 843 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count); 844 } 845 846 HeapWord* 847 G1CollectedHeap::mem_allocate(size_t word_size, 848 bool* gc_overhead_limit_was_exceeded) { 849 assert_heap_not_locked_and_not_at_safepoint(); 850 851 // Loop until the allocation is satisfied, or unsatisfied after GC. 852 for (int try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 853 unsigned int gc_count_before; 854 855 HeapWord* result = NULL; 856 if (!isHumongous(word_size)) { 857 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count); 858 } else { 859 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count); 860 } 861 if (result != NULL) { 862 return result; 863 } 864 865 // Create the garbage collection operation... 866 VM_G1CollectForAllocation op(gc_count_before, word_size); 867 // ...and get the VM thread to execute it. 868 VMThread::execute(&op); 869 870 if (op.prologue_succeeded() && op.pause_succeeded()) { 871 // If the operation was successful we'll return the result even 872 // if it is NULL. If the allocation attempt failed immediately 873 // after a Full GC, it's unlikely we'll be able to allocate now. 874 HeapWord* result = op.result(); 875 if (result != NULL && !isHumongous(word_size)) { 876 // Allocations that take place on VM operations do not do any 877 // card dirtying and we have to do it here. We only have to do 878 // this for non-humongous allocations, though. 879 dirty_young_block(result, word_size); 880 } 881 return result; 882 } else { 883 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 884 return NULL; 885 } 886 assert(op.result() == NULL, 887 "the result should be NULL if the VM op did not succeed"); 888 } 889 890 // Give a warning if we seem to be looping forever. 891 if ((QueuedAllocationWarningCount > 0) && 892 (try_count % QueuedAllocationWarningCount == 0)) { 893 warning("G1CollectedHeap::mem_allocate retries %d times", try_count); 894 } 895 } 896 897 ShouldNotReachHere(); 898 return NULL; 899 } 900 901 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size, 902 unsigned int *gc_count_before_ret, 903 int* gclocker_retry_count_ret) { 904 // Make sure you read the note in attempt_allocation_humongous(). 905 906 assert_heap_not_locked_and_not_at_safepoint(); 907 assert(!isHumongous(word_size), "attempt_allocation_slow() should not " 908 "be called for humongous allocation requests"); 909 910 // We should only get here after the first-level allocation attempt 911 // (attempt_allocation()) failed to allocate. 912 913 // We will loop until a) we manage to successfully perform the 914 // allocation or b) we successfully schedule a collection which 915 // fails to perform the allocation. b) is the only case when we'll 916 // return NULL. 917 HeapWord* result = NULL; 918 for (int try_count = 1; /* we'll return */; try_count += 1) { 919 bool should_try_gc; 920 unsigned int gc_count_before; 921 922 { 923 MutexLockerEx x(Heap_lock); 924 925 result = _mutator_alloc_region.attempt_allocation_locked(word_size, 926 false /* bot_updates */); 927 if (result != NULL) { 928 return result; 929 } 930 931 // If we reach here, attempt_allocation_locked() above failed to 932 // allocate a new region. So the mutator alloc region should be NULL. 933 assert(_mutator_alloc_region.get() == NULL, "only way to get here"); 934 935 if (GC_locker::is_active_and_needs_gc()) { 936 if (g1_policy()->can_expand_young_list()) { 937 // No need for an ergo verbose message here, 938 // can_expand_young_list() does this when it returns true. 939 result = _mutator_alloc_region.attempt_allocation_force(word_size, 940 false /* bot_updates */); 941 if (result != NULL) { 942 return result; 943 } 944 } 945 should_try_gc = false; 946 } else { 947 // The GCLocker may not be active but the GCLocker initiated 948 // GC may not yet have been performed (GCLocker::needs_gc() 949 // returns true). In this case we do not try this GC and 950 // wait until the GCLocker initiated GC is performed, and 951 // then retry the allocation. 952 if (GC_locker::needs_gc()) { 953 should_try_gc = false; 954 } else { 955 // Read the GC count while still holding the Heap_lock. 956 gc_count_before = total_collections(); 957 should_try_gc = true; 958 } 959 } 960 } 961 962 if (should_try_gc) { 963 bool succeeded; 964 result = do_collection_pause(word_size, gc_count_before, &succeeded, 965 GCCause::_g1_inc_collection_pause); 966 if (result != NULL) { 967 assert(succeeded, "only way to get back a non-NULL result"); 968 return result; 969 } 970 971 if (succeeded) { 972 // If we get here we successfully scheduled a collection which 973 // failed to allocate. No point in trying to allocate 974 // further. We'll just return NULL. 975 MutexLockerEx x(Heap_lock); 976 *gc_count_before_ret = total_collections(); 977 return NULL; 978 } 979 } else { 980 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { 981 MutexLockerEx x(Heap_lock); 982 *gc_count_before_ret = total_collections(); 983 return NULL; 984 } 985 // The GCLocker is either active or the GCLocker initiated 986 // GC has not yet been performed. Stall until it is and 987 // then retry the allocation. 988 GC_locker::stall_until_clear(); 989 (*gclocker_retry_count_ret) += 1; 990 } 991 992 // We can reach here if we were unsuccessful in scheduling a 993 // collection (because another thread beat us to it) or if we were 994 // stalled due to the GC locker. In either can we should retry the 995 // allocation attempt in case another thread successfully 996 // performed a collection and reclaimed enough space. We do the 997 // first attempt (without holding the Heap_lock) here and the 998 // follow-on attempt will be at the start of the next loop 999 // iteration (after taking the Heap_lock). 1000 result = _mutator_alloc_region.attempt_allocation(word_size, 1001 false /* bot_updates */); 1002 if (result != NULL) { 1003 return result; 1004 } 1005 1006 // Give a warning if we seem to be looping forever. 1007 if ((QueuedAllocationWarningCount > 0) && 1008 (try_count % QueuedAllocationWarningCount == 0)) { 1009 warning("G1CollectedHeap::attempt_allocation_slow() " 1010 "retries %d times", try_count); 1011 } 1012 } 1013 1014 ShouldNotReachHere(); 1015 return NULL; 1016 } 1017 1018 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size, 1019 unsigned int * gc_count_before_ret, 1020 int* gclocker_retry_count_ret) { 1021 // The structure of this method has a lot of similarities to 1022 // attempt_allocation_slow(). The reason these two were not merged 1023 // into a single one is that such a method would require several "if 1024 // allocation is not humongous do this, otherwise do that" 1025 // conditional paths which would obscure its flow. In fact, an early 1026 // version of this code did use a unified method which was harder to 1027 // follow and, as a result, it had subtle bugs that were hard to 1028 // track down. So keeping these two methods separate allows each to 1029 // be more readable. It will be good to keep these two in sync as 1030 // much as possible. 1031 1032 assert_heap_not_locked_and_not_at_safepoint(); 1033 assert(isHumongous(word_size), "attempt_allocation_humongous() " 1034 "should only be called for humongous allocations"); 1035 1036 // Humongous objects can exhaust the heap quickly, so we should check if we 1037 // need to start a marking cycle at each humongous object allocation. We do 1038 // the check before we do the actual allocation. The reason for doing it 1039 // before the allocation is that we avoid having to keep track of the newly 1040 // allocated memory while we do a GC. 1041 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation", 1042 word_size)) { 1043 collect(GCCause::_g1_humongous_allocation); 1044 } 1045 1046 // We will loop until a) we manage to successfully perform the 1047 // allocation or b) we successfully schedule a collection which 1048 // fails to perform the allocation. b) is the only case when we'll 1049 // return NULL. 1050 HeapWord* result = NULL; 1051 for (int try_count = 1; /* we'll return */; try_count += 1) { 1052 bool should_try_gc; 1053 unsigned int gc_count_before; 1054 1055 { 1056 MutexLockerEx x(Heap_lock); 1057 1058 // Given that humongous objects are not allocated in young 1059 // regions, we'll first try to do the allocation without doing a 1060 // collection hoping that there's enough space in the heap. 1061 result = humongous_obj_allocate(word_size); 1062 if (result != NULL) { 1063 return result; 1064 } 1065 1066 if (GC_locker::is_active_and_needs_gc()) { 1067 should_try_gc = false; 1068 } else { 1069 // The GCLocker may not be active but the GCLocker initiated 1070 // GC may not yet have been performed (GCLocker::needs_gc() 1071 // returns true). In this case we do not try this GC and 1072 // wait until the GCLocker initiated GC is performed, and 1073 // then retry the allocation. 1074 if (GC_locker::needs_gc()) { 1075 should_try_gc = false; 1076 } else { 1077 // Read the GC count while still holding the Heap_lock. 1078 gc_count_before = total_collections(); 1079 should_try_gc = true; 1080 } 1081 } 1082 } 1083 1084 if (should_try_gc) { 1085 // If we failed to allocate the humongous object, we should try to 1086 // do a collection pause (if we're allowed) in case it reclaims 1087 // enough space for the allocation to succeed after the pause. 1088 1089 bool succeeded; 1090 result = do_collection_pause(word_size, gc_count_before, &succeeded, 1091 GCCause::_g1_humongous_allocation); 1092 if (result != NULL) { 1093 assert(succeeded, "only way to get back a non-NULL result"); 1094 return result; 1095 } 1096 1097 if (succeeded) { 1098 // If we get here we successfully scheduled a collection which 1099 // failed to allocate. No point in trying to allocate 1100 // further. We'll just return NULL. 1101 MutexLockerEx x(Heap_lock); 1102 *gc_count_before_ret = total_collections(); 1103 return NULL; 1104 } 1105 } else { 1106 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { 1107 MutexLockerEx x(Heap_lock); 1108 *gc_count_before_ret = total_collections(); 1109 return NULL; 1110 } 1111 // The GCLocker is either active or the GCLocker initiated 1112 // GC has not yet been performed. Stall until it is and 1113 // then retry the allocation. 1114 GC_locker::stall_until_clear(); 1115 (*gclocker_retry_count_ret) += 1; 1116 } 1117 1118 // We can reach here if we were unsuccessful in scheduling a 1119 // collection (because another thread beat us to it) or if we were 1120 // stalled due to the GC locker. In either can we should retry the 1121 // allocation attempt in case another thread successfully 1122 // performed a collection and reclaimed enough space. Give a 1123 // warning if we seem to be looping forever. 1124 1125 if ((QueuedAllocationWarningCount > 0) && 1126 (try_count % QueuedAllocationWarningCount == 0)) { 1127 warning("G1CollectedHeap::attempt_allocation_humongous() " 1128 "retries %d times", try_count); 1129 } 1130 } 1131 1132 ShouldNotReachHere(); 1133 return NULL; 1134 } 1135 1136 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size, 1137 bool expect_null_mutator_alloc_region) { 1138 assert_at_safepoint(true /* should_be_vm_thread */); 1139 assert(_mutator_alloc_region.get() == NULL || 1140 !expect_null_mutator_alloc_region, 1141 "the current alloc region was unexpectedly found to be non-NULL"); 1142 1143 if (!isHumongous(word_size)) { 1144 return _mutator_alloc_region.attempt_allocation_locked(word_size, 1145 false /* bot_updates */); 1146 } else { 1147 HeapWord* result = humongous_obj_allocate(word_size); 1148 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) { 1149 g1_policy()->set_initiate_conc_mark_if_possible(); 1150 } 1151 return result; 1152 } 1153 1154 ShouldNotReachHere(); 1155 } 1156 1157 class PostMCRemSetClearClosure: public HeapRegionClosure { 1158 G1CollectedHeap* _g1h; 1159 ModRefBarrierSet* _mr_bs; 1160 public: 1161 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) : 1162 _g1h(g1h), _mr_bs(mr_bs) {} 1163 1164 bool doHeapRegion(HeapRegion* r) { 1165 HeapRegionRemSet* hrrs = r->rem_set(); 1166 1167 if (r->continuesHumongous()) { 1168 // We'll assert that the strong code root list and RSet is empty 1169 assert(hrrs->strong_code_roots_list_length() == 0, "sanity"); 1170 assert(hrrs->occupied() == 0, "RSet should be empty"); 1171 return false; 1172 } 1173 1174 _g1h->reset_gc_time_stamps(r); 1175 hrrs->clear(); 1176 // You might think here that we could clear just the cards 1177 // corresponding to the used region. But no: if we leave a dirty card 1178 // in a region we might allocate into, then it would prevent that card 1179 // from being enqueued, and cause it to be missed. 1180 // Re: the performance cost: we shouldn't be doing full GC anyway! 1181 _mr_bs->clear(MemRegion(r->bottom(), r->end())); 1182 1183 return false; 1184 } 1185 }; 1186 1187 void G1CollectedHeap::clear_rsets_post_compaction() { 1188 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set()); 1189 heap_region_iterate(&rs_clear); 1190 } 1191 1192 class RebuildRSOutOfRegionClosure: public HeapRegionClosure { 1193 G1CollectedHeap* _g1h; 1194 UpdateRSOopClosure _cl; 1195 int _worker_i; 1196 public: 1197 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) : 1198 _cl(g1->g1_rem_set(), worker_i), 1199 _worker_i(worker_i), 1200 _g1h(g1) 1201 { } 1202 1203 bool doHeapRegion(HeapRegion* r) { 1204 if (!r->continuesHumongous()) { 1205 _cl.set_from(r); 1206 r->oop_iterate(&_cl); 1207 } 1208 return false; 1209 } 1210 }; 1211 1212 class ParRebuildRSTask: public AbstractGangTask { 1213 G1CollectedHeap* _g1; 1214 public: 1215 ParRebuildRSTask(G1CollectedHeap* g1) 1216 : AbstractGangTask("ParRebuildRSTask"), 1217 _g1(g1) 1218 { } 1219 1220 void work(uint worker_id) { 1221 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id); 1222 _g1->heap_region_par_iterate_chunked(&rebuild_rs, worker_id, 1223 _g1->workers()->active_workers(), 1224 HeapRegion::RebuildRSClaimValue); 1225 } 1226 }; 1227 1228 class PostCompactionPrinterClosure: public HeapRegionClosure { 1229 private: 1230 G1HRPrinter* _hr_printer; 1231 public: 1232 bool doHeapRegion(HeapRegion* hr) { 1233 assert(!hr->is_young(), "not expecting to find young regions"); 1234 // We only generate output for non-empty regions. 1235 if (!hr->is_empty()) { 1236 if (!hr->isHumongous()) { 1237 _hr_printer->post_compaction(hr, G1HRPrinter::Old); 1238 } else if (hr->startsHumongous()) { 1239 if (hr->region_num() == 1) { 1240 // single humongous region 1241 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous); 1242 } else { 1243 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous); 1244 } 1245 } else { 1246 assert(hr->continuesHumongous(), "only way to get here"); 1247 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous); 1248 } 1249 } 1250 return false; 1251 } 1252 1253 PostCompactionPrinterClosure(G1HRPrinter* hr_printer) 1254 : _hr_printer(hr_printer) { } 1255 }; 1256 1257 void G1CollectedHeap::print_hrs_post_compaction() { 1258 PostCompactionPrinterClosure cl(hr_printer()); 1259 heap_region_iterate(&cl); 1260 } 1261 1262 bool G1CollectedHeap::do_collection(bool explicit_gc, 1263 bool clear_all_soft_refs, 1264 size_t word_size) { 1265 assert_at_safepoint(true /* should_be_vm_thread */); 1266 1267 if (GC_locker::check_active_before_gc()) { 1268 return false; 1269 } 1270 1271 STWGCTimer* gc_timer = G1MarkSweep::gc_timer(); 1272 gc_timer->register_gc_start(); 1273 1274 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer(); 1275 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start()); 1276 1277 SvcGCMarker sgcm(SvcGCMarker::FULL); 1278 ResourceMark rm; 1279 1280 print_heap_before_gc(); 1281 trace_heap_before_gc(gc_tracer); 1282 1283 size_t metadata_prev_used = MetaspaceAux::used_bytes(); 1284 1285 verify_region_sets_optional(); 1286 1287 const bool do_clear_all_soft_refs = clear_all_soft_refs || 1288 collector_policy()->should_clear_all_soft_refs(); 1289 1290 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy()); 1291 1292 { 1293 IsGCActiveMark x; 1294 1295 // Timing 1296 assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant"); 1297 gclog_or_tty->date_stamp(G1Log::fine() && PrintGCDateStamps); 1298 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty); 1299 1300 { 1301 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL, gc_tracer->gc_id()); 1302 TraceCollectorStats tcs(g1mm()->full_collection_counters()); 1303 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause()); 1304 1305 double start = os::elapsedTime(); 1306 g1_policy()->record_full_collection_start(); 1307 1308 // Note: When we have a more flexible GC logging framework that 1309 // allows us to add optional attributes to a GC log record we 1310 // could consider timing and reporting how long we wait in the 1311 // following two methods. 1312 wait_while_free_regions_coming(); 1313 // If we start the compaction before the CM threads finish 1314 // scanning the root regions we might trip them over as we'll 1315 // be moving objects / updating references. So let's wait until 1316 // they are done. By telling them to abort, they should complete 1317 // early. 1318 _cm->root_regions()->abort(); 1319 _cm->root_regions()->wait_until_scan_finished(); 1320 append_secondary_free_list_if_not_empty_with_lock(); 1321 1322 gc_prologue(true); 1323 increment_total_collections(true /* full gc */); 1324 increment_old_marking_cycles_started(); 1325 1326 assert(used() == recalculate_used(), "Should be equal"); 1327 1328 verify_before_gc(); 1329 1330 check_bitmaps("Full GC Start"); 1331 pre_full_gc_dump(gc_timer); 1332 1333 COMPILER2_PRESENT(DerivedPointerTable::clear()); 1334 1335 // Disable discovery and empty the discovered lists 1336 // for the CM ref processor. 1337 ref_processor_cm()->disable_discovery(); 1338 ref_processor_cm()->abandon_partial_discovery(); 1339 ref_processor_cm()->verify_no_references_recorded(); 1340 1341 // Abandon current iterations of concurrent marking and concurrent 1342 // refinement, if any are in progress. We have to do this before 1343 // wait_until_scan_finished() below. 1344 concurrent_mark()->abort(); 1345 1346 // Make sure we'll choose a new allocation region afterwards. 1347 release_mutator_alloc_region(); 1348 abandon_gc_alloc_regions(); 1349 g1_rem_set()->cleanupHRRS(); 1350 1351 // We should call this after we retire any currently active alloc 1352 // regions so that all the ALLOC / RETIRE events are generated 1353 // before the start GC event. 1354 _hr_printer.start_gc(true /* full */, (size_t) total_collections()); 1355 1356 // We may have added regions to the current incremental collection 1357 // set between the last GC or pause and now. We need to clear the 1358 // incremental collection set and then start rebuilding it afresh 1359 // after this full GC. 1360 abandon_collection_set(g1_policy()->inc_cset_head()); 1361 g1_policy()->clear_incremental_cset(); 1362 g1_policy()->stop_incremental_cset_building(); 1363 1364 tear_down_region_sets(false /* free_list_only */); 1365 g1_policy()->set_gcs_are_young(true); 1366 1367 // See the comments in g1CollectedHeap.hpp and 1368 // G1CollectedHeap::ref_processing_init() about 1369 // how reference processing currently works in G1. 1370 1371 // Temporarily make discovery by the STW ref processor single threaded (non-MT). 1372 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false); 1373 1374 // Temporarily clear the STW ref processor's _is_alive_non_header field. 1375 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL); 1376 1377 ref_processor_stw()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/); 1378 ref_processor_stw()->setup_policy(do_clear_all_soft_refs); 1379 1380 // Do collection work 1381 { 1382 HandleMark hm; // Discard invalid handles created during gc 1383 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs); 1384 } 1385 1386 assert(free_regions() == 0, "we should not have added any free regions"); 1387 rebuild_region_sets(false /* free_list_only */); 1388 1389 // Enqueue any discovered reference objects that have 1390 // not been removed from the discovered lists. 1391 ref_processor_stw()->enqueue_discovered_references(); 1392 1393 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 1394 1395 MemoryService::track_memory_usage(); 1396 1397 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 1398 ref_processor_stw()->verify_no_references_recorded(); 1399 1400 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 1401 ClassLoaderDataGraph::purge(); 1402 MetaspaceAux::verify_metrics(); 1403 1404 // Note: since we've just done a full GC, concurrent 1405 // marking is no longer active. Therefore we need not 1406 // re-enable reference discovery for the CM ref processor. 1407 // That will be done at the start of the next marking cycle. 1408 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition"); 1409 ref_processor_cm()->verify_no_references_recorded(); 1410 1411 reset_gc_time_stamp(); 1412 // Since everything potentially moved, we will clear all remembered 1413 // sets, and clear all cards. Later we will rebuild remembered 1414 // sets. We will also reset the GC time stamps of the regions. 1415 clear_rsets_post_compaction(); 1416 check_gc_time_stamps(); 1417 1418 // Resize the heap if necessary. 1419 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size); 1420 1421 if (_hr_printer.is_active()) { 1422 // We should do this after we potentially resize the heap so 1423 // that all the COMMIT / UNCOMMIT events are generated before 1424 // the end GC event. 1425 1426 print_hrs_post_compaction(); 1427 _hr_printer.end_gc(true /* full */, (size_t) total_collections()); 1428 } 1429 1430 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 1431 if (hot_card_cache->use_cache()) { 1432 hot_card_cache->reset_card_counts(); 1433 hot_card_cache->reset_hot_cache(); 1434 } 1435 1436 // Rebuild remembered sets of all regions. 1437 if (G1CollectedHeap::use_parallel_gc_threads()) { 1438 uint n_workers = 1439 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 1440 workers()->active_workers(), 1441 Threads::number_of_non_daemon_threads()); 1442 assert(UseDynamicNumberOfGCThreads || 1443 n_workers == workers()->total_workers(), 1444 "If not dynamic should be using all the workers"); 1445 workers()->set_active_workers(n_workers); 1446 // Set parallel threads in the heap (_n_par_threads) only 1447 // before a parallel phase and always reset it to 0 after 1448 // the phase so that the number of parallel threads does 1449 // no get carried forward to a serial phase where there 1450 // may be code that is "possibly_parallel". 1451 set_par_threads(n_workers); 1452 1453 ParRebuildRSTask rebuild_rs_task(this); 1454 assert(check_heap_region_claim_values( 1455 HeapRegion::InitialClaimValue), "sanity check"); 1456 assert(UseDynamicNumberOfGCThreads || 1457 workers()->active_workers() == workers()->total_workers(), 1458 "Unless dynamic should use total workers"); 1459 // Use the most recent number of active workers 1460 assert(workers()->active_workers() > 0, 1461 "Active workers not properly set"); 1462 set_par_threads(workers()->active_workers()); 1463 workers()->run_task(&rebuild_rs_task); 1464 set_par_threads(0); 1465 assert(check_heap_region_claim_values( 1466 HeapRegion::RebuildRSClaimValue), "sanity check"); 1467 reset_heap_region_claim_values(); 1468 } else { 1469 RebuildRSOutOfRegionClosure rebuild_rs(this); 1470 heap_region_iterate(&rebuild_rs); 1471 } 1472 1473 // Rebuild the strong code root lists for each region 1474 rebuild_strong_code_roots(); 1475 1476 if (true) { // FIXME 1477 MetaspaceGC::compute_new_size(); 1478 } 1479 1480 #ifdef TRACESPINNING 1481 ParallelTaskTerminator::print_termination_counts(); 1482 #endif 1483 1484 // Discard all rset updates 1485 JavaThread::dirty_card_queue_set().abandon_logs(); 1486 assert(!G1DeferredRSUpdate 1487 || (G1DeferredRSUpdate && 1488 (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any"); 1489 1490 _young_list->reset_sampled_info(); 1491 // At this point there should be no regions in the 1492 // entire heap tagged as young. 1493 assert(check_young_list_empty(true /* check_heap */), 1494 "young list should be empty at this point"); 1495 1496 // Update the number of full collections that have been completed. 1497 increment_old_marking_cycles_completed(false /* concurrent */); 1498 1499 _hrs.verify_optional(); 1500 verify_region_sets_optional(); 1501 1502 verify_after_gc(); 1503 1504 // Clear the previous marking bitmap, if needed for bitmap verification. 1505 // Note we cannot do this when we clear the next marking bitmap in 1506 // ConcurrentMark::abort() above since VerifyDuringGC verifies the 1507 // objects marked during a full GC against the previous bitmap. 1508 // But we need to clear it before calling check_bitmaps below since 1509 // the full GC has compacted objects and updated TAMS but not updated 1510 // the prev bitmap. 1511 if (G1VerifyBitmaps) { 1512 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll(); 1513 } 1514 check_bitmaps("Full GC End"); 1515 1516 // Start a new incremental collection set for the next pause 1517 assert(g1_policy()->collection_set() == NULL, "must be"); 1518 g1_policy()->start_incremental_cset_building(); 1519 1520 clear_cset_fast_test(); 1521 1522 init_mutator_alloc_region(); 1523 1524 double end = os::elapsedTime(); 1525 g1_policy()->record_full_collection_end(); 1526 1527 if (G1Log::fine()) { 1528 g1_policy()->print_heap_transition(); 1529 } 1530 1531 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 1532 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 1533 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 1534 // before any GC notifications are raised. 1535 g1mm()->update_sizes(); 1536 1537 gc_epilogue(true); 1538 } 1539 1540 if (G1Log::finer()) { 1541 g1_policy()->print_detailed_heap_transition(true /* full */); 1542 } 1543 1544 print_heap_after_gc(); 1545 trace_heap_after_gc(gc_tracer); 1546 1547 post_full_gc_dump(gc_timer); 1548 1549 gc_timer->register_gc_end(); 1550 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions()); 1551 } 1552 1553 return true; 1554 } 1555 1556 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) { 1557 // do_collection() will return whether it succeeded in performing 1558 // the GC. Currently, there is no facility on the 1559 // do_full_collection() API to notify the caller than the collection 1560 // did not succeed (e.g., because it was locked out by the GC 1561 // locker). So, right now, we'll ignore the return value. 1562 bool dummy = do_collection(true, /* explicit_gc */ 1563 clear_all_soft_refs, 1564 0 /* word_size */); 1565 } 1566 1567 // This code is mostly copied from TenuredGeneration. 1568 void 1569 G1CollectedHeap:: 1570 resize_if_necessary_after_full_collection(size_t word_size) { 1571 // Include the current allocation, if any, and bytes that will be 1572 // pre-allocated to support collections, as "used". 1573 const size_t used_after_gc = used(); 1574 const size_t capacity_after_gc = capacity(); 1575 const size_t free_after_gc = capacity_after_gc - used_after_gc; 1576 1577 // This is enforced in arguments.cpp. 1578 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, 1579 "otherwise the code below doesn't make sense"); 1580 1581 // We don't have floating point command-line arguments 1582 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0; 1583 const double maximum_used_percentage = 1.0 - minimum_free_percentage; 1584 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0; 1585 const double minimum_used_percentage = 1.0 - maximum_free_percentage; 1586 1587 const size_t min_heap_size = collector_policy()->min_heap_byte_size(); 1588 const size_t max_heap_size = collector_policy()->max_heap_byte_size(); 1589 1590 // We have to be careful here as these two calculations can overflow 1591 // 32-bit size_t's. 1592 double used_after_gc_d = (double) used_after_gc; 1593 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage; 1594 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage; 1595 1596 // Let's make sure that they are both under the max heap size, which 1597 // by default will make them fit into a size_t. 1598 double desired_capacity_upper_bound = (double) max_heap_size; 1599 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d, 1600 desired_capacity_upper_bound); 1601 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d, 1602 desired_capacity_upper_bound); 1603 1604 // We can now safely turn them into size_t's. 1605 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d; 1606 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d; 1607 1608 // This assert only makes sense here, before we adjust them 1609 // with respect to the min and max heap size. 1610 assert(minimum_desired_capacity <= maximum_desired_capacity, 1611 err_msg("minimum_desired_capacity = "SIZE_FORMAT", " 1612 "maximum_desired_capacity = "SIZE_FORMAT, 1613 minimum_desired_capacity, maximum_desired_capacity)); 1614 1615 // Should not be greater than the heap max size. No need to adjust 1616 // it with respect to the heap min size as it's a lower bound (i.e., 1617 // we'll try to make the capacity larger than it, not smaller). 1618 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size); 1619 // Should not be less than the heap min size. No need to adjust it 1620 // with respect to the heap max size as it's an upper bound (i.e., 1621 // we'll try to make the capacity smaller than it, not greater). 1622 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size); 1623 1624 if (capacity_after_gc < minimum_desired_capacity) { 1625 // Don't expand unless it's significant 1626 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc; 1627 ergo_verbose4(ErgoHeapSizing, 1628 "attempt heap expansion", 1629 ergo_format_reason("capacity lower than " 1630 "min desired capacity after Full GC") 1631 ergo_format_byte("capacity") 1632 ergo_format_byte("occupancy") 1633 ergo_format_byte_perc("min desired capacity"), 1634 capacity_after_gc, used_after_gc, 1635 minimum_desired_capacity, (double) MinHeapFreeRatio); 1636 expand(expand_bytes); 1637 1638 // No expansion, now see if we want to shrink 1639 } else if (capacity_after_gc > maximum_desired_capacity) { 1640 // Capacity too large, compute shrinking size 1641 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity; 1642 ergo_verbose4(ErgoHeapSizing, 1643 "attempt heap shrinking", 1644 ergo_format_reason("capacity higher than " 1645 "max desired capacity after Full GC") 1646 ergo_format_byte("capacity") 1647 ergo_format_byte("occupancy") 1648 ergo_format_byte_perc("max desired capacity"), 1649 capacity_after_gc, used_after_gc, 1650 maximum_desired_capacity, (double) MaxHeapFreeRatio); 1651 shrink(shrink_bytes); 1652 } 1653 } 1654 1655 1656 HeapWord* 1657 G1CollectedHeap::satisfy_failed_allocation(size_t word_size, 1658 bool* succeeded) { 1659 assert_at_safepoint(true /* should_be_vm_thread */); 1660 1661 *succeeded = true; 1662 // Let's attempt the allocation first. 1663 HeapWord* result = 1664 attempt_allocation_at_safepoint(word_size, 1665 false /* expect_null_mutator_alloc_region */); 1666 if (result != NULL) { 1667 assert(*succeeded, "sanity"); 1668 return result; 1669 } 1670 1671 // In a G1 heap, we're supposed to keep allocation from failing by 1672 // incremental pauses. Therefore, at least for now, we'll favor 1673 // expansion over collection. (This might change in the future if we can 1674 // do something smarter than full collection to satisfy a failed alloc.) 1675 result = expand_and_allocate(word_size); 1676 if (result != NULL) { 1677 assert(*succeeded, "sanity"); 1678 return result; 1679 } 1680 1681 // Expansion didn't work, we'll try to do a Full GC. 1682 bool gc_succeeded = do_collection(false, /* explicit_gc */ 1683 false, /* clear_all_soft_refs */ 1684 word_size); 1685 if (!gc_succeeded) { 1686 *succeeded = false; 1687 return NULL; 1688 } 1689 1690 // Retry the allocation 1691 result = attempt_allocation_at_safepoint(word_size, 1692 true /* expect_null_mutator_alloc_region */); 1693 if (result != NULL) { 1694 assert(*succeeded, "sanity"); 1695 return result; 1696 } 1697 1698 // Then, try a Full GC that will collect all soft references. 1699 gc_succeeded = do_collection(false, /* explicit_gc */ 1700 true, /* clear_all_soft_refs */ 1701 word_size); 1702 if (!gc_succeeded) { 1703 *succeeded = false; 1704 return NULL; 1705 } 1706 1707 // Retry the allocation once more 1708 result = attempt_allocation_at_safepoint(word_size, 1709 true /* expect_null_mutator_alloc_region */); 1710 if (result != NULL) { 1711 assert(*succeeded, "sanity"); 1712 return result; 1713 } 1714 1715 assert(!collector_policy()->should_clear_all_soft_refs(), 1716 "Flag should have been handled and cleared prior to this point"); 1717 1718 // What else? We might try synchronous finalization later. If the total 1719 // space available is large enough for the allocation, then a more 1720 // complete compaction phase than we've tried so far might be 1721 // appropriate. 1722 assert(*succeeded, "sanity"); 1723 return NULL; 1724 } 1725 1726 // Attempting to expand the heap sufficiently 1727 // to support an allocation of the given "word_size". If 1728 // successful, perform the allocation and return the address of the 1729 // allocated block, or else "NULL". 1730 1731 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) { 1732 assert_at_safepoint(true /* should_be_vm_thread */); 1733 1734 verify_region_sets_optional(); 1735 1736 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes); 1737 ergo_verbose1(ErgoHeapSizing, 1738 "attempt heap expansion", 1739 ergo_format_reason("allocation request failed") 1740 ergo_format_byte("allocation request"), 1741 word_size * HeapWordSize); 1742 if (expand(expand_bytes)) { 1743 _hrs.verify_optional(); 1744 verify_region_sets_optional(); 1745 return attempt_allocation_at_safepoint(word_size, 1746 false /* expect_null_mutator_alloc_region */); 1747 } 1748 return NULL; 1749 } 1750 1751 void G1CollectedHeap::update_committed_space(HeapWord* old_end, 1752 HeapWord* new_end) { 1753 assert(old_end != new_end, "don't call this otherwise"); 1754 assert((HeapWord*) _g1_storage.high() == new_end, "invariant"); 1755 1756 // Update the committed mem region. 1757 _g1_committed.set_end(new_end); 1758 // Tell the card table about the update. 1759 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed); 1760 // Tell the BOT about the update. 1761 _bot_shared->resize(_g1_committed.word_size()); 1762 // Tell the hot card cache about the update 1763 _cg1r->hot_card_cache()->resize_card_counts(capacity()); 1764 } 1765 1766 bool G1CollectedHeap::expand(size_t expand_bytes) { 1767 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); 1768 aligned_expand_bytes = align_size_up(aligned_expand_bytes, 1769 HeapRegion::GrainBytes); 1770 ergo_verbose2(ErgoHeapSizing, 1771 "expand the heap", 1772 ergo_format_byte("requested expansion amount") 1773 ergo_format_byte("attempted expansion amount"), 1774 expand_bytes, aligned_expand_bytes); 1775 1776 if (_g1_storage.uncommitted_size() == 0) { 1777 ergo_verbose0(ErgoHeapSizing, 1778 "did not expand the heap", 1779 ergo_format_reason("heap already fully expanded")); 1780 return false; 1781 } 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 aligned_shrink_bytes = 1842 ReservedSpace::page_align_size_down(shrink_bytes); 1843 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes, 1844 HeapRegion::GrainBytes); 1845 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes); 1846 1847 uint num_regions_removed = _hrs.shrink_by(num_regions_to_remove); 1848 HeapWord* old_end = (HeapWord*) _g1_storage.high(); 1849 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes; 1850 1851 ergo_verbose3(ErgoHeapSizing, 1852 "shrink the heap", 1853 ergo_format_byte("requested shrinking amount") 1854 ergo_format_byte("aligned shrinking amount") 1855 ergo_format_byte("attempted shrinking amount"), 1856 shrink_bytes, aligned_shrink_bytes, shrunk_bytes); 1857 if (num_regions_removed > 0) { 1858 _g1_storage.shrink_by(shrunk_bytes); 1859 HeapWord* new_end = (HeapWord*) _g1_storage.high(); 1860 1861 if (_hr_printer.is_active()) { 1862 HeapWord* curr = old_end; 1863 while (curr > new_end) { 1864 HeapWord* curr_end = curr; 1865 curr -= HeapRegion::GrainWords; 1866 _hr_printer.uncommit(curr, curr_end); 1867 } 1868 } 1869 1870 _expansion_regions += num_regions_removed; 1871 update_committed_space(old_end, new_end); 1872 HeapRegionRemSet::shrink_heap(n_regions()); 1873 g1_policy()->record_new_heap_size(n_regions()); 1874 } else { 1875 ergo_verbose0(ErgoHeapSizing, 1876 "did not shrink the heap", 1877 ergo_format_reason("heap shrinking operation failed")); 1878 } 1879 } 1880 1881 void G1CollectedHeap::shrink(size_t shrink_bytes) { 1882 verify_region_sets_optional(); 1883 1884 // We should only reach here at the end of a Full GC which means we 1885 // should not not be holding to any GC alloc regions. The method 1886 // below will make sure of that and do any remaining clean up. 1887 abandon_gc_alloc_regions(); 1888 1889 // Instead of tearing down / rebuilding the free lists here, we 1890 // could instead use the remove_all_pending() method on free_list to 1891 // remove only the ones that we need to remove. 1892 tear_down_region_sets(true /* free_list_only */); 1893 shrink_helper(shrink_bytes); 1894 rebuild_region_sets(true /* free_list_only */); 1895 1896 _hrs.verify_optional(); 1897 verify_region_sets_optional(); 1898 } 1899 1900 // Public methods. 1901 1902 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away 1903 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list 1904 #endif // _MSC_VER 1905 1906 1907 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) : 1908 SharedHeap(policy_), 1909 _g1_policy(policy_), 1910 _dirty_card_queue_set(false), 1911 _into_cset_dirty_card_queue_set(false), 1912 _is_alive_closure_cm(this), 1913 _is_alive_closure_stw(this), 1914 _ref_processor_cm(NULL), 1915 _ref_processor_stw(NULL), 1916 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)), 1917 _bot_shared(NULL), 1918 _evac_failure_scan_stack(NULL), 1919 _mark_in_progress(false), 1920 _cg1r(NULL), _summary_bytes_used(0), 1921 _g1mm(NULL), 1922 _refine_cte_cl(NULL), 1923 _full_collection(false), 1924 _free_list("Master Free List", new MasterFreeRegionListMtSafeChecker()), 1925 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()), 1926 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()), 1927 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()), 1928 _free_regions_coming(false), 1929 _young_list(new YoungList(this)), 1930 _gc_time_stamp(0), 1931 _retained_old_gc_alloc_region(NULL), 1932 _survivor_plab_stats(YoungPLABSize, PLABWeight), 1933 _old_plab_stats(OldPLABSize, PLABWeight), 1934 _expand_heap_after_alloc_failure(true), 1935 _surviving_young_words(NULL), 1936 _old_marking_cycles_started(0), 1937 _old_marking_cycles_completed(0), 1938 _concurrent_cycle_started(false), 1939 _in_cset_fast_test(), 1940 _dirty_cards_region_list(NULL), 1941 _worker_cset_start_region(NULL), 1942 _worker_cset_start_region_time_stamp(NULL), 1943 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()), 1944 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()), 1945 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()), 1946 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) { 1947 1948 _g1h = this; 1949 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) { 1950 vm_exit_during_initialization("Failed necessary allocation."); 1951 } 1952 1953 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2; 1954 1955 int n_queues = MAX2((int)ParallelGCThreads, 1); 1956 _task_queues = new RefToScanQueueSet(n_queues); 1957 1958 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets(); 1959 assert(n_rem_sets > 0, "Invariant."); 1960 1961 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC); 1962 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(unsigned int, n_queues, mtGC); 1963 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC); 1964 1965 for (int i = 0; i < n_queues; i++) { 1966 RefToScanQueue* q = new RefToScanQueue(); 1967 q->initialize(); 1968 _task_queues->register_queue(i, q); 1969 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo(); 1970 } 1971 clear_cset_start_regions(); 1972 1973 // Initialize the G1EvacuationFailureALot counters and flags. 1974 NOT_PRODUCT(reset_evacuation_should_fail();) 1975 1976 guarantee(_task_queues != NULL, "task_queues allocation failure."); 1977 } 1978 1979 jint G1CollectedHeap::initialize() { 1980 CollectedHeap::pre_initialize(); 1981 os::enable_vtime(); 1982 1983 G1Log::init(); 1984 1985 // Necessary to satisfy locking discipline assertions. 1986 1987 MutexLocker x(Heap_lock); 1988 1989 // We have to initialize the printer before committing the heap, as 1990 // it will be used then. 1991 _hr_printer.set_active(G1PrintHeapRegions); 1992 1993 // While there are no constraints in the GC code that HeapWordSize 1994 // be any particular value, there are multiple other areas in the 1995 // system which believe this to be true (e.g. oop->object_size in some 1996 // cases incorrectly returns the size in wordSize units rather than 1997 // HeapWordSize). 1998 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 1999 2000 size_t init_byte_size = collector_policy()->initial_heap_byte_size(); 2001 size_t max_byte_size = collector_policy()->max_heap_byte_size(); 2002 size_t heap_alignment = collector_policy()->heap_alignment(); 2003 2004 // Ensure that the sizes are properly aligned. 2005 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap"); 2006 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap"); 2007 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap"); 2008 2009 _refine_cte_cl = new RefineCardTableEntryClosure(); 2010 2011 _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl); 2012 2013 // Reserve the maximum. 2014 2015 // When compressed oops are enabled, the preferred heap base 2016 // is calculated by subtracting the requested size from the 2017 // 32Gb boundary and using the result as the base address for 2018 // heap reservation. If the requested size is not aligned to 2019 // HeapRegion::GrainBytes (i.e. the alignment that is passed 2020 // into the ReservedHeapSpace constructor) then the actual 2021 // base of the reserved heap may end up differing from the 2022 // address that was requested (i.e. the preferred heap base). 2023 // If this happens then we could end up using a non-optimal 2024 // compressed oops mode. 2025 2026 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size, 2027 heap_alignment); 2028 2029 // It is important to do this in a way such that concurrent readers can't 2030 // temporarily think something is in the heap. (I've actually seen this 2031 // happen in asserts: DLD.) 2032 _reserved.set_word_size(0); 2033 _reserved.set_start((HeapWord*)heap_rs.base()); 2034 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size())); 2035 2036 _expansion_regions = (uint) (max_byte_size / HeapRegion::GrainBytes); 2037 2038 // Create the gen rem set (and barrier set) for the entire reserved region. 2039 _rem_set = collector_policy()->create_rem_set(_reserved, 2); 2040 set_barrier_set(rem_set()->bs()); 2041 if (!barrier_set()->is_a(BarrierSet::G1SATBCTLogging)) { 2042 vm_exit_during_initialization("G1 requires a G1SATBLoggingCardTableModRefBS"); 2043 return JNI_ENOMEM; 2044 } 2045 2046 // Also create a G1 rem set. 2047 _g1_rem_set = new G1RemSet(this, g1_barrier_set()); 2048 2049 // Carve out the G1 part of the heap. 2050 2051 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size); 2052 _g1_reserved = MemRegion((HeapWord*)g1_rs.base(), 2053 g1_rs.size()/HeapWordSize); 2054 2055 _g1_storage.initialize(g1_rs, 0); 2056 _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0); 2057 _hrs.initialize((HeapWord*) _g1_reserved.start(), 2058 (HeapWord*) _g1_reserved.end()); 2059 assert(_hrs.max_length() == _expansion_regions, 2060 err_msg("max length: %u expansion regions: %u", 2061 _hrs.max_length(), _expansion_regions)); 2062 2063 // Do later initialization work for concurrent refinement. 2064 _cg1r->init(); 2065 2066 // 6843694 - ensure that the maximum region index can fit 2067 // in the remembered set structures. 2068 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; 2069 guarantee((max_regions() - 1) <= max_region_idx, "too many regions"); 2070 2071 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; 2072 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); 2073 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region, 2074 "too many cards per region"); 2075 2076 FreeRegionList::set_unrealistically_long_length(max_regions() + 1); 2077 2078 _bot_shared = new G1BlockOffsetSharedArray(_reserved, 2079 heap_word_size(init_byte_size)); 2080 2081 _g1h = this; 2082 2083 _in_cset_fast_test.initialize(_g1_reserved.start(), _g1_reserved.end(), HeapRegion::GrainBytes); 2084 2085 // Create the ConcurrentMark data structure and thread. 2086 // (Must do this late, so that "max_regions" is defined.) 2087 _cm = new ConcurrentMark(this, heap_rs); 2088 if (_cm == NULL || !_cm->completed_initialization()) { 2089 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark"); 2090 return JNI_ENOMEM; 2091 } 2092 _cmThread = _cm->cmThread(); 2093 2094 // Initialize the from_card cache structure of HeapRegionRemSet. 2095 HeapRegionRemSet::init_heap(max_regions()); 2096 2097 // Now expand into the initial heap size. 2098 if (!expand(init_byte_size)) { 2099 vm_shutdown_during_initialization("Failed to allocate initial heap."); 2100 return JNI_ENOMEM; 2101 } 2102 2103 // Perform any initialization actions delegated to the policy. 2104 g1_policy()->init(); 2105 2106 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon, 2107 SATB_Q_FL_lock, 2108 G1SATBProcessCompletedThreshold, 2109 Shared_SATB_Q_lock); 2110 2111 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl, 2112 DirtyCardQ_CBL_mon, 2113 DirtyCardQ_FL_lock, 2114 concurrent_g1_refine()->yellow_zone(), 2115 concurrent_g1_refine()->red_zone(), 2116 Shared_DirtyCardQ_lock); 2117 2118 if (G1DeferredRSUpdate) { 2119 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code 2120 DirtyCardQ_CBL_mon, 2121 DirtyCardQ_FL_lock, 2122 -1, // never trigger processing 2123 -1, // no limit on length 2124 Shared_DirtyCardQ_lock, 2125 &JavaThread::dirty_card_queue_set()); 2126 } 2127 2128 // Initialize the card queue set used to hold cards containing 2129 // references into the collection set. 2130 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code 2131 DirtyCardQ_CBL_mon, 2132 DirtyCardQ_FL_lock, 2133 -1, // never trigger processing 2134 -1, // no limit on length 2135 Shared_DirtyCardQ_lock, 2136 &JavaThread::dirty_card_queue_set()); 2137 2138 // In case we're keeping closure specialization stats, initialize those 2139 // counts and that mechanism. 2140 SpecializationStats::clear(); 2141 2142 // Here we allocate the dummy full region that is required by the 2143 // G1AllocRegion class. If we don't pass an address in the reserved 2144 // space here, lots of asserts fire. 2145 2146 HeapRegion* dummy_region = new_heap_region(0 /* index of bottom region */, 2147 _g1_reserved.start()); 2148 // We'll re-use the same region whether the alloc region will 2149 // require BOT updates or not and, if it doesn't, then a non-young 2150 // region will complain that it cannot support allocations without 2151 // BOT updates. So we'll tag the dummy region as young to avoid that. 2152 dummy_region->set_young(); 2153 // Make sure it's full. 2154 dummy_region->set_top(dummy_region->end()); 2155 G1AllocRegion::setup(this, dummy_region); 2156 2157 init_mutator_alloc_region(); 2158 2159 // Do create of the monitoring and management support so that 2160 // values in the heap have been properly initialized. 2161 _g1mm = new G1MonitoringSupport(this); 2162 2163 G1StringDedup::initialize(); 2164 2165 return JNI_OK; 2166 } 2167 2168 void G1CollectedHeap::stop() { 2169 // Stop all concurrent threads. We do this to make sure these threads 2170 // do not continue to execute and access resources (e.g. gclog_or_tty) 2171 // that are destroyed during shutdown. 2172 _cg1r->stop(); 2173 _cmThread->stop(); 2174 if (G1StringDedup::is_enabled()) { 2175 G1StringDedup::stop(); 2176 } 2177 } 2178 2179 size_t G1CollectedHeap::conservative_max_heap_alignment() { 2180 return HeapRegion::max_region_size(); 2181 } 2182 2183 void G1CollectedHeap::ref_processing_init() { 2184 // Reference processing in G1 currently works as follows: 2185 // 2186 // * There are two reference processor instances. One is 2187 // used to record and process discovered references 2188 // during concurrent marking; the other is used to 2189 // record and process references during STW pauses 2190 // (both full and incremental). 2191 // * Both ref processors need to 'span' the entire heap as 2192 // the regions in the collection set may be dotted around. 2193 // 2194 // * For the concurrent marking ref processor: 2195 // * Reference discovery is enabled at initial marking. 2196 // * Reference discovery is disabled and the discovered 2197 // references processed etc during remarking. 2198 // * Reference discovery is MT (see below). 2199 // * Reference discovery requires a barrier (see below). 2200 // * Reference processing may or may not be MT 2201 // (depending on the value of ParallelRefProcEnabled 2202 // and ParallelGCThreads). 2203 // * A full GC disables reference discovery by the CM 2204 // ref processor and abandons any entries on it's 2205 // discovered lists. 2206 // 2207 // * For the STW processor: 2208 // * Non MT discovery is enabled at the start of a full GC. 2209 // * Processing and enqueueing during a full GC is non-MT. 2210 // * During a full GC, references are processed after marking. 2211 // 2212 // * Discovery (may or may not be MT) is enabled at the start 2213 // of an incremental evacuation pause. 2214 // * References are processed near the end of a STW evacuation pause. 2215 // * For both types of GC: 2216 // * Discovery is atomic - i.e. not concurrent. 2217 // * Reference discovery will not need a barrier. 2218 2219 SharedHeap::ref_processing_init(); 2220 MemRegion mr = reserved_region(); 2221 2222 // Concurrent Mark ref processor 2223 _ref_processor_cm = 2224 new ReferenceProcessor(mr, // span 2225 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2226 // mt processing 2227 (int) ParallelGCThreads, 2228 // degree of mt processing 2229 (ParallelGCThreads > 1) || (ConcGCThreads > 1), 2230 // mt discovery 2231 (int) MAX2(ParallelGCThreads, ConcGCThreads), 2232 // degree of mt discovery 2233 false, 2234 // Reference discovery is not atomic 2235 &_is_alive_closure_cm); 2236 // is alive closure 2237 // (for efficiency/performance) 2238 2239 // STW ref processor 2240 _ref_processor_stw = 2241 new ReferenceProcessor(mr, // span 2242 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2243 // mt processing 2244 MAX2((int)ParallelGCThreads, 1), 2245 // degree of mt processing 2246 (ParallelGCThreads > 1), 2247 // mt discovery 2248 MAX2((int)ParallelGCThreads, 1), 2249 // degree of mt discovery 2250 true, 2251 // Reference discovery is atomic 2252 &_is_alive_closure_stw); 2253 // is alive closure 2254 // (for efficiency/performance) 2255 } 2256 2257 size_t G1CollectedHeap::capacity() const { 2258 return _g1_committed.byte_size(); 2259 } 2260 2261 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) { 2262 assert(!hr->continuesHumongous(), "pre-condition"); 2263 hr->reset_gc_time_stamp(); 2264 if (hr->startsHumongous()) { 2265 uint first_index = hr->hrs_index() + 1; 2266 uint last_index = hr->last_hc_index(); 2267 for (uint i = first_index; i < last_index; i += 1) { 2268 HeapRegion* chr = region_at(i); 2269 assert(chr->continuesHumongous(), "sanity"); 2270 chr->reset_gc_time_stamp(); 2271 } 2272 } 2273 } 2274 2275 #ifndef PRODUCT 2276 class CheckGCTimeStampsHRClosure : public HeapRegionClosure { 2277 private: 2278 unsigned _gc_time_stamp; 2279 bool _failures; 2280 2281 public: 2282 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) : 2283 _gc_time_stamp(gc_time_stamp), _failures(false) { } 2284 2285 virtual bool doHeapRegion(HeapRegion* hr) { 2286 unsigned region_gc_time_stamp = hr->get_gc_time_stamp(); 2287 if (_gc_time_stamp != region_gc_time_stamp) { 2288 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, " 2289 "expected %d", HR_FORMAT_PARAMS(hr), 2290 region_gc_time_stamp, _gc_time_stamp); 2291 _failures = true; 2292 } 2293 return false; 2294 } 2295 2296 bool failures() { return _failures; } 2297 }; 2298 2299 void G1CollectedHeap::check_gc_time_stamps() { 2300 CheckGCTimeStampsHRClosure cl(_gc_time_stamp); 2301 heap_region_iterate(&cl); 2302 guarantee(!cl.failures(), "all GC time stamps should have been reset"); 2303 } 2304 #endif // PRODUCT 2305 2306 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, 2307 DirtyCardQueue* into_cset_dcq, 2308 bool concurrent, 2309 uint worker_i) { 2310 // Clean cards in the hot card cache 2311 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 2312 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq); 2313 2314 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 2315 int n_completed_buffers = 0; 2316 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) { 2317 n_completed_buffers++; 2318 } 2319 g1_policy()->phase_times()->record_update_rs_processed_buffers(worker_i, n_completed_buffers); 2320 dcqs.clear_n_completed_buffers(); 2321 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!"); 2322 } 2323 2324 2325 // Computes the sum of the storage used by the various regions. 2326 2327 size_t G1CollectedHeap::used() const { 2328 assert(Heap_lock->owner() != NULL, 2329 "Should be owned on this thread's behalf."); 2330 size_t result = _summary_bytes_used; 2331 // Read only once in case it is set to NULL concurrently 2332 HeapRegion* hr = _mutator_alloc_region.get(); 2333 if (hr != NULL) 2334 result += hr->used(); 2335 return result; 2336 } 2337 2338 size_t G1CollectedHeap::used_unlocked() const { 2339 size_t result = _summary_bytes_used; 2340 return result; 2341 } 2342 2343 class SumUsedClosure: public HeapRegionClosure { 2344 size_t _used; 2345 public: 2346 SumUsedClosure() : _used(0) {} 2347 bool doHeapRegion(HeapRegion* r) { 2348 if (!r->continuesHumongous()) { 2349 _used += r->used(); 2350 } 2351 return false; 2352 } 2353 size_t result() { return _used; } 2354 }; 2355 2356 size_t G1CollectedHeap::recalculate_used() const { 2357 double recalculate_used_start = os::elapsedTime(); 2358 2359 SumUsedClosure blk; 2360 heap_region_iterate(&blk); 2361 2362 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0); 2363 return blk.result(); 2364 } 2365 2366 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 2367 switch (cause) { 2368 case GCCause::_gc_locker: return GCLockerInvokesConcurrent; 2369 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent; 2370 case GCCause::_g1_humongous_allocation: return true; 2371 default: return false; 2372 } 2373 } 2374 2375 #ifndef PRODUCT 2376 void G1CollectedHeap::allocate_dummy_regions() { 2377 // Let's fill up most of the region 2378 size_t word_size = HeapRegion::GrainWords - 1024; 2379 // And as a result the region we'll allocate will be humongous. 2380 guarantee(isHumongous(word_size), "sanity"); 2381 2382 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) { 2383 // Let's use the existing mechanism for the allocation 2384 HeapWord* dummy_obj = humongous_obj_allocate(word_size); 2385 if (dummy_obj != NULL) { 2386 MemRegion mr(dummy_obj, word_size); 2387 CollectedHeap::fill_with_object(mr); 2388 } else { 2389 // If we can't allocate once, we probably cannot allocate 2390 // again. Let's get out of the loop. 2391 break; 2392 } 2393 } 2394 } 2395 #endif // !PRODUCT 2396 2397 void G1CollectedHeap::increment_old_marking_cycles_started() { 2398 assert(_old_marking_cycles_started == _old_marking_cycles_completed || 2399 _old_marking_cycles_started == _old_marking_cycles_completed + 1, 2400 err_msg("Wrong marking cycle count (started: %d, completed: %d)", 2401 _old_marking_cycles_started, _old_marking_cycles_completed)); 2402 2403 _old_marking_cycles_started++; 2404 } 2405 2406 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) { 2407 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 2408 2409 // We assume that if concurrent == true, then the caller is a 2410 // concurrent thread that was joined the Suspendible Thread 2411 // Set. If there's ever a cheap way to check this, we should add an 2412 // assert here. 2413 2414 // Given that this method is called at the end of a Full GC or of a 2415 // concurrent cycle, and those can be nested (i.e., a Full GC can 2416 // interrupt a concurrent cycle), the number of full collections 2417 // completed should be either one (in the case where there was no 2418 // nesting) or two (when a Full GC interrupted a concurrent cycle) 2419 // behind the number of full collections started. 2420 2421 // This is the case for the inner caller, i.e. a Full GC. 2422 assert(concurrent || 2423 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || 2424 (_old_marking_cycles_started == _old_marking_cycles_completed + 2), 2425 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u " 2426 "is inconsistent with _old_marking_cycles_completed = %u", 2427 _old_marking_cycles_started, _old_marking_cycles_completed)); 2428 2429 // This is the case for the outer caller, i.e. the concurrent cycle. 2430 assert(!concurrent || 2431 (_old_marking_cycles_started == _old_marking_cycles_completed + 1), 2432 err_msg("for outer caller (concurrent cycle): " 2433 "_old_marking_cycles_started = %u " 2434 "is inconsistent with _old_marking_cycles_completed = %u", 2435 _old_marking_cycles_started, _old_marking_cycles_completed)); 2436 2437 _old_marking_cycles_completed += 1; 2438 2439 // We need to clear the "in_progress" flag in the CM thread before 2440 // we wake up any waiters (especially when ExplicitInvokesConcurrent 2441 // is set) so that if a waiter requests another System.gc() it doesn't 2442 // incorrectly see that a marking cycle is still in progress. 2443 if (concurrent) { 2444 _cmThread->clear_in_progress(); 2445 } 2446 2447 // This notify_all() will ensure that a thread that called 2448 // System.gc() with (with ExplicitGCInvokesConcurrent set or not) 2449 // and it's waiting for a full GC to finish will be woken up. It is 2450 // waiting in VM_G1IncCollectionPause::doit_epilogue(). 2451 FullGCCount_lock->notify_all(); 2452 } 2453 2454 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) { 2455 _concurrent_cycle_started = true; 2456 _gc_timer_cm->register_gc_start(start_time); 2457 2458 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start()); 2459 trace_heap_before_gc(_gc_tracer_cm); 2460 } 2461 2462 void G1CollectedHeap::register_concurrent_cycle_end() { 2463 if (_concurrent_cycle_started) { 2464 if (_cm->has_aborted()) { 2465 _gc_tracer_cm->report_concurrent_mode_failure(); 2466 } 2467 2468 _gc_timer_cm->register_gc_end(); 2469 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions()); 2470 2471 _concurrent_cycle_started = false; 2472 } 2473 } 2474 2475 void G1CollectedHeap::trace_heap_after_concurrent_cycle() { 2476 if (_concurrent_cycle_started) { 2477 trace_heap_after_gc(_gc_tracer_cm); 2478 } 2479 } 2480 2481 G1YCType G1CollectedHeap::yc_type() { 2482 bool is_young = g1_policy()->gcs_are_young(); 2483 bool is_initial_mark = g1_policy()->during_initial_mark_pause(); 2484 bool is_during_mark = mark_in_progress(); 2485 2486 if (is_initial_mark) { 2487 return InitialMark; 2488 } else if (is_during_mark) { 2489 return DuringMark; 2490 } else if (is_young) { 2491 return Normal; 2492 } else { 2493 return Mixed; 2494 } 2495 } 2496 2497 void G1CollectedHeap::collect(GCCause::Cause cause) { 2498 assert_heap_not_locked(); 2499 2500 unsigned int gc_count_before; 2501 unsigned int old_marking_count_before; 2502 bool retry_gc; 2503 2504 do { 2505 retry_gc = false; 2506 2507 { 2508 MutexLocker ml(Heap_lock); 2509 2510 // Read the GC count while holding the Heap_lock 2511 gc_count_before = total_collections(); 2512 old_marking_count_before = _old_marking_cycles_started; 2513 } 2514 2515 if (should_do_concurrent_full_gc(cause)) { 2516 // Schedule an initial-mark evacuation pause that will start a 2517 // concurrent cycle. We're setting word_size to 0 which means that 2518 // we are not requesting a post-GC allocation. 2519 VM_G1IncCollectionPause op(gc_count_before, 2520 0, /* word_size */ 2521 true, /* should_initiate_conc_mark */ 2522 g1_policy()->max_pause_time_ms(), 2523 cause); 2524 2525 VMThread::execute(&op); 2526 if (!op.pause_succeeded()) { 2527 if (old_marking_count_before == _old_marking_cycles_started) { 2528 retry_gc = op.should_retry_gc(); 2529 } else { 2530 // A Full GC happened while we were trying to schedule the 2531 // initial-mark GC. No point in starting a new cycle given 2532 // that the whole heap was collected anyway. 2533 } 2534 2535 if (retry_gc) { 2536 if (GC_locker::is_active_and_needs_gc()) { 2537 GC_locker::stall_until_clear(); 2538 } 2539 } 2540 } 2541 } else { 2542 if (cause == GCCause::_gc_locker 2543 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { 2544 2545 // Schedule a standard evacuation pause. We're setting word_size 2546 // to 0 which means that we are not requesting a post-GC allocation. 2547 VM_G1IncCollectionPause op(gc_count_before, 2548 0, /* word_size */ 2549 false, /* should_initiate_conc_mark */ 2550 g1_policy()->max_pause_time_ms(), 2551 cause); 2552 VMThread::execute(&op); 2553 } else { 2554 // Schedule a Full GC. 2555 VM_G1CollectFull op(gc_count_before, old_marking_count_before, cause); 2556 VMThread::execute(&op); 2557 } 2558 } 2559 } while (retry_gc); 2560 } 2561 2562 bool G1CollectedHeap::is_in(const void* p) const { 2563 if (_g1_committed.contains(p)) { 2564 // Given that we know that p is in the committed space, 2565 // heap_region_containing_raw() should successfully 2566 // return the containing region. 2567 HeapRegion* hr = heap_region_containing_raw(p); 2568 return hr->is_in(p); 2569 } else { 2570 return false; 2571 } 2572 } 2573 2574 // Iteration functions. 2575 2576 // Iterates an OopClosure over all ref-containing fields of objects 2577 // within a HeapRegion. 2578 2579 class IterateOopClosureRegionClosure: public HeapRegionClosure { 2580 MemRegion _mr; 2581 ExtendedOopClosure* _cl; 2582 public: 2583 IterateOopClosureRegionClosure(MemRegion mr, ExtendedOopClosure* cl) 2584 : _mr(mr), _cl(cl) {} 2585 bool doHeapRegion(HeapRegion* r) { 2586 if (!r->continuesHumongous()) { 2587 r->oop_iterate(_cl); 2588 } 2589 return false; 2590 } 2591 }; 2592 2593 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) { 2594 IterateOopClosureRegionClosure blk(_g1_committed, cl); 2595 heap_region_iterate(&blk); 2596 } 2597 2598 void G1CollectedHeap::oop_iterate(MemRegion mr, ExtendedOopClosure* cl) { 2599 IterateOopClosureRegionClosure blk(mr, cl); 2600 heap_region_iterate(&blk); 2601 } 2602 2603 // Iterates an ObjectClosure over all objects within a HeapRegion. 2604 2605 class IterateObjectClosureRegionClosure: public HeapRegionClosure { 2606 ObjectClosure* _cl; 2607 public: 2608 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} 2609 bool doHeapRegion(HeapRegion* r) { 2610 if (! r->continuesHumongous()) { 2611 r->object_iterate(_cl); 2612 } 2613 return false; 2614 } 2615 }; 2616 2617 void G1CollectedHeap::object_iterate(ObjectClosure* cl) { 2618 IterateObjectClosureRegionClosure blk(cl); 2619 heap_region_iterate(&blk); 2620 } 2621 2622 // Calls a SpaceClosure on a HeapRegion. 2623 2624 class SpaceClosureRegionClosure: public HeapRegionClosure { 2625 SpaceClosure* _cl; 2626 public: 2627 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {} 2628 bool doHeapRegion(HeapRegion* r) { 2629 _cl->do_space(r); 2630 return false; 2631 } 2632 }; 2633 2634 void G1CollectedHeap::space_iterate(SpaceClosure* cl) { 2635 SpaceClosureRegionClosure blk(cl); 2636 heap_region_iterate(&blk); 2637 } 2638 2639 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { 2640 _hrs.iterate(cl); 2641 } 2642 2643 void 2644 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl, 2645 uint worker_id, 2646 uint no_of_par_workers, 2647 jint claim_value) { 2648 const uint regions = n_regions(); 2649 const uint max_workers = (G1CollectedHeap::use_parallel_gc_threads() ? 2650 no_of_par_workers : 2651 1); 2652 assert(UseDynamicNumberOfGCThreads || 2653 no_of_par_workers == workers()->total_workers(), 2654 "Non dynamic should use fixed number of workers"); 2655 // try to spread out the starting points of the workers 2656 const HeapRegion* start_hr = 2657 start_region_for_worker(worker_id, no_of_par_workers); 2658 const uint start_index = start_hr->hrs_index(); 2659 2660 // each worker will actually look at all regions 2661 for (uint count = 0; count < regions; ++count) { 2662 const uint index = (start_index + count) % regions; 2663 assert(0 <= index && index < regions, "sanity"); 2664 HeapRegion* r = region_at(index); 2665 // we'll ignore "continues humongous" regions (we'll process them 2666 // when we come across their corresponding "start humongous" 2667 // region) and regions already claimed 2668 if (r->claim_value() == claim_value || r->continuesHumongous()) { 2669 continue; 2670 } 2671 // OK, try to claim it 2672 if (r->claimHeapRegion(claim_value)) { 2673 // success! 2674 assert(!r->continuesHumongous(), "sanity"); 2675 if (r->startsHumongous()) { 2676 // If the region is "starts humongous" we'll iterate over its 2677 // "continues humongous" first; in fact we'll do them 2678 // first. The order is important. In on case, calling the 2679 // closure on the "starts humongous" region might de-allocate 2680 // and clear all its "continues humongous" regions and, as a 2681 // result, we might end up processing them twice. So, we'll do 2682 // them first (notice: most closures will ignore them anyway) and 2683 // then we'll do the "starts humongous" region. 2684 for (uint ch_index = index + 1; ch_index < regions; ++ch_index) { 2685 HeapRegion* chr = region_at(ch_index); 2686 2687 // if the region has already been claimed or it's not 2688 // "continues humongous" we're done 2689 if (chr->claim_value() == claim_value || 2690 !chr->continuesHumongous()) { 2691 break; 2692 } 2693 2694 // No one should have claimed it directly. We can given 2695 // that we claimed its "starts humongous" region. 2696 assert(chr->claim_value() != claim_value, "sanity"); 2697 assert(chr->humongous_start_region() == r, "sanity"); 2698 2699 if (chr->claimHeapRegion(claim_value)) { 2700 // we should always be able to claim it; no one else should 2701 // be trying to claim this region 2702 2703 bool res2 = cl->doHeapRegion(chr); 2704 assert(!res2, "Should not abort"); 2705 2706 // Right now, this holds (i.e., no closure that actually 2707 // does something with "continues humongous" regions 2708 // clears them). We might have to weaken it in the future, 2709 // but let's leave these two asserts here for extra safety. 2710 assert(chr->continuesHumongous(), "should still be the case"); 2711 assert(chr->humongous_start_region() == r, "sanity"); 2712 } else { 2713 guarantee(false, "we should not reach here"); 2714 } 2715 } 2716 } 2717 2718 assert(!r->continuesHumongous(), "sanity"); 2719 bool res = cl->doHeapRegion(r); 2720 assert(!res, "Should not abort"); 2721 } 2722 } 2723 } 2724 2725 class ResetClaimValuesClosure: public HeapRegionClosure { 2726 public: 2727 bool doHeapRegion(HeapRegion* r) { 2728 r->set_claim_value(HeapRegion::InitialClaimValue); 2729 return false; 2730 } 2731 }; 2732 2733 void G1CollectedHeap::reset_heap_region_claim_values() { 2734 ResetClaimValuesClosure blk; 2735 heap_region_iterate(&blk); 2736 } 2737 2738 void G1CollectedHeap::reset_cset_heap_region_claim_values() { 2739 ResetClaimValuesClosure blk; 2740 collection_set_iterate(&blk); 2741 } 2742 2743 #ifdef ASSERT 2744 // This checks whether all regions in the heap have the correct claim 2745 // value. I also piggy-backed on this a check to ensure that the 2746 // humongous_start_region() information on "continues humongous" 2747 // regions is correct. 2748 2749 class CheckClaimValuesClosure : public HeapRegionClosure { 2750 private: 2751 jint _claim_value; 2752 uint _failures; 2753 HeapRegion* _sh_region; 2754 2755 public: 2756 CheckClaimValuesClosure(jint claim_value) : 2757 _claim_value(claim_value), _failures(0), _sh_region(NULL) { } 2758 bool doHeapRegion(HeapRegion* r) { 2759 if (r->claim_value() != _claim_value) { 2760 gclog_or_tty->print_cr("Region " HR_FORMAT ", " 2761 "claim value = %d, should be %d", 2762 HR_FORMAT_PARAMS(r), 2763 r->claim_value(), _claim_value); 2764 ++_failures; 2765 } 2766 if (!r->isHumongous()) { 2767 _sh_region = NULL; 2768 } else if (r->startsHumongous()) { 2769 _sh_region = r; 2770 } else if (r->continuesHumongous()) { 2771 if (r->humongous_start_region() != _sh_region) { 2772 gclog_or_tty->print_cr("Region " HR_FORMAT ", " 2773 "HS = "PTR_FORMAT", should be "PTR_FORMAT, 2774 HR_FORMAT_PARAMS(r), 2775 r->humongous_start_region(), 2776 _sh_region); 2777 ++_failures; 2778 } 2779 } 2780 return false; 2781 } 2782 uint failures() { return _failures; } 2783 }; 2784 2785 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) { 2786 CheckClaimValuesClosure cl(claim_value); 2787 heap_region_iterate(&cl); 2788 return cl.failures() == 0; 2789 } 2790 2791 class CheckClaimValuesInCSetHRClosure: public HeapRegionClosure { 2792 private: 2793 jint _claim_value; 2794 uint _failures; 2795 2796 public: 2797 CheckClaimValuesInCSetHRClosure(jint claim_value) : 2798 _claim_value(claim_value), _failures(0) { } 2799 2800 uint failures() { return _failures; } 2801 2802 bool doHeapRegion(HeapRegion* hr) { 2803 assert(hr->in_collection_set(), "how?"); 2804 assert(!hr->isHumongous(), "H-region in CSet"); 2805 if (hr->claim_value() != _claim_value) { 2806 gclog_or_tty->print_cr("CSet Region " HR_FORMAT ", " 2807 "claim value = %d, should be %d", 2808 HR_FORMAT_PARAMS(hr), 2809 hr->claim_value(), _claim_value); 2810 _failures += 1; 2811 } 2812 return false; 2813 } 2814 }; 2815 2816 bool G1CollectedHeap::check_cset_heap_region_claim_values(jint claim_value) { 2817 CheckClaimValuesInCSetHRClosure cl(claim_value); 2818 collection_set_iterate(&cl); 2819 return cl.failures() == 0; 2820 } 2821 #endif // ASSERT 2822 2823 // Clear the cached CSet starting regions and (more importantly) 2824 // the time stamps. Called when we reset the GC time stamp. 2825 void G1CollectedHeap::clear_cset_start_regions() { 2826 assert(_worker_cset_start_region != NULL, "sanity"); 2827 assert(_worker_cset_start_region_time_stamp != NULL, "sanity"); 2828 2829 int n_queues = MAX2((int)ParallelGCThreads, 1); 2830 for (int i = 0; i < n_queues; i++) { 2831 _worker_cset_start_region[i] = NULL; 2832 _worker_cset_start_region_time_stamp[i] = 0; 2833 } 2834 } 2835 2836 // Given the id of a worker, obtain or calculate a suitable 2837 // starting region for iterating over the current collection set. 2838 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) { 2839 assert(get_gc_time_stamp() > 0, "should have been updated by now"); 2840 2841 HeapRegion* result = NULL; 2842 unsigned gc_time_stamp = get_gc_time_stamp(); 2843 2844 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) { 2845 // Cached starting region for current worker was set 2846 // during the current pause - so it's valid. 2847 // Note: the cached starting heap region may be NULL 2848 // (when the collection set is empty). 2849 result = _worker_cset_start_region[worker_i]; 2850 assert(result == NULL || result->in_collection_set(), "sanity"); 2851 return result; 2852 } 2853 2854 // The cached entry was not valid so let's calculate 2855 // a suitable starting heap region for this worker. 2856 2857 // We want the parallel threads to start their collection 2858 // set iteration at different collection set regions to 2859 // avoid contention. 2860 // If we have: 2861 // n collection set regions 2862 // p threads 2863 // Then thread t will start at region floor ((t * n) / p) 2864 2865 result = g1_policy()->collection_set(); 2866 if (G1CollectedHeap::use_parallel_gc_threads()) { 2867 uint cs_size = g1_policy()->cset_region_length(); 2868 uint active_workers = workers()->active_workers(); 2869 assert(UseDynamicNumberOfGCThreads || 2870 active_workers == workers()->total_workers(), 2871 "Unless dynamic should use total workers"); 2872 2873 uint end_ind = (cs_size * worker_i) / active_workers; 2874 uint start_ind = 0; 2875 2876 if (worker_i > 0 && 2877 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) { 2878 // Previous workers starting region is valid 2879 // so let's iterate from there 2880 start_ind = (cs_size * (worker_i - 1)) / active_workers; 2881 result = _worker_cset_start_region[worker_i - 1]; 2882 } 2883 2884 for (uint i = start_ind; i < end_ind; i++) { 2885 result = result->next_in_collection_set(); 2886 } 2887 } 2888 2889 // Note: the calculated starting heap region may be NULL 2890 // (when the collection set is empty). 2891 assert(result == NULL || result->in_collection_set(), "sanity"); 2892 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp, 2893 "should be updated only once per pause"); 2894 _worker_cset_start_region[worker_i] = result; 2895 OrderAccess::storestore(); 2896 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp; 2897 return result; 2898 } 2899 2900 HeapRegion* G1CollectedHeap::start_region_for_worker(uint worker_i, 2901 uint no_of_par_workers) { 2902 uint worker_num = 2903 G1CollectedHeap::use_parallel_gc_threads() ? no_of_par_workers : 1U; 2904 assert(UseDynamicNumberOfGCThreads || 2905 no_of_par_workers == workers()->total_workers(), 2906 "Non dynamic should use fixed number of workers"); 2907 const uint start_index = n_regions() * worker_i / worker_num; 2908 return region_at(start_index); 2909 } 2910 2911 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) { 2912 HeapRegion* r = g1_policy()->collection_set(); 2913 while (r != NULL) { 2914 HeapRegion* next = r->next_in_collection_set(); 2915 if (cl->doHeapRegion(r)) { 2916 cl->incomplete(); 2917 return; 2918 } 2919 r = next; 2920 } 2921 } 2922 2923 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r, 2924 HeapRegionClosure *cl) { 2925 if (r == NULL) { 2926 // The CSet is empty so there's nothing to do. 2927 return; 2928 } 2929 2930 assert(r->in_collection_set(), 2931 "Start region must be a member of the collection set."); 2932 HeapRegion* cur = r; 2933 while (cur != NULL) { 2934 HeapRegion* next = cur->next_in_collection_set(); 2935 if (cl->doHeapRegion(cur) && false) { 2936 cl->incomplete(); 2937 return; 2938 } 2939 cur = next; 2940 } 2941 cur = g1_policy()->collection_set(); 2942 while (cur != r) { 2943 HeapRegion* next = cur->next_in_collection_set(); 2944 if (cl->doHeapRegion(cur) && false) { 2945 cl->incomplete(); 2946 return; 2947 } 2948 cur = next; 2949 } 2950 } 2951 2952 CompactibleSpace* G1CollectedHeap::first_compactible_space() { 2953 return n_regions() > 0 ? region_at(0) : NULL; 2954 } 2955 2956 2957 Space* G1CollectedHeap::space_containing(const void* addr) const { 2958 return heap_region_containing(addr); 2959 } 2960 2961 HeapWord* G1CollectedHeap::block_start(const void* addr) const { 2962 Space* sp = space_containing(addr); 2963 return sp->block_start(addr); 2964 } 2965 2966 size_t G1CollectedHeap::block_size(const HeapWord* addr) const { 2967 Space* sp = space_containing(addr); 2968 return sp->block_size(addr); 2969 } 2970 2971 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { 2972 Space* sp = space_containing(addr); 2973 return sp->block_is_obj(addr); 2974 } 2975 2976 bool G1CollectedHeap::supports_tlab_allocation() const { 2977 return true; 2978 } 2979 2980 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { 2981 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes; 2982 } 2983 2984 size_t G1CollectedHeap::tlab_used(Thread* ignored) const { 2985 return young_list()->eden_used_bytes(); 2986 } 2987 2988 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size 2989 // must be smaller than the humongous object limit. 2990 size_t G1CollectedHeap::max_tlab_size() const { 2991 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment); 2992 } 2993 2994 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { 2995 // Return the remaining space in the cur alloc region, but not less than 2996 // the min TLAB size. 2997 2998 // Also, this value can be at most the humongous object threshold, 2999 // since we can't allow tlabs to grow big enough to accommodate 3000 // humongous objects. 3001 3002 HeapRegion* hr = _mutator_alloc_region.get(); 3003 size_t max_tlab = max_tlab_size() * wordSize; 3004 if (hr == NULL) { 3005 return max_tlab; 3006 } else { 3007 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab); 3008 } 3009 } 3010 3011 size_t G1CollectedHeap::max_capacity() const { 3012 return _g1_reserved.byte_size(); 3013 } 3014 3015 jlong G1CollectedHeap::millis_since_last_gc() { 3016 // assert(false, "NYI"); 3017 return 0; 3018 } 3019 3020 void G1CollectedHeap::prepare_for_verify() { 3021 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) { 3022 ensure_parsability(false); 3023 } 3024 g1_rem_set()->prepare_for_verify(); 3025 } 3026 3027 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr, 3028 VerifyOption vo) { 3029 switch (vo) { 3030 case VerifyOption_G1UsePrevMarking: 3031 return hr->obj_allocated_since_prev_marking(obj); 3032 case VerifyOption_G1UseNextMarking: 3033 return hr->obj_allocated_since_next_marking(obj); 3034 case VerifyOption_G1UseMarkWord: 3035 return false; 3036 default: 3037 ShouldNotReachHere(); 3038 } 3039 return false; // keep some compilers happy 3040 } 3041 3042 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) { 3043 switch (vo) { 3044 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start(); 3045 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start(); 3046 case VerifyOption_G1UseMarkWord: return NULL; 3047 default: ShouldNotReachHere(); 3048 } 3049 return NULL; // keep some compilers happy 3050 } 3051 3052 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) { 3053 switch (vo) { 3054 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj); 3055 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj); 3056 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked(); 3057 default: ShouldNotReachHere(); 3058 } 3059 return false; // keep some compilers happy 3060 } 3061 3062 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) { 3063 switch (vo) { 3064 case VerifyOption_G1UsePrevMarking: return "PTAMS"; 3065 case VerifyOption_G1UseNextMarking: return "NTAMS"; 3066 case VerifyOption_G1UseMarkWord: return "NONE"; 3067 default: ShouldNotReachHere(); 3068 } 3069 return NULL; // keep some compilers happy 3070 } 3071 3072 class VerifyRootsClosure: public OopClosure { 3073 private: 3074 G1CollectedHeap* _g1h; 3075 VerifyOption _vo; 3076 bool _failures; 3077 public: 3078 // _vo == UsePrevMarking -> use "prev" marking information, 3079 // _vo == UseNextMarking -> use "next" marking information, 3080 // _vo == UseMarkWord -> use mark word from object header. 3081 VerifyRootsClosure(VerifyOption vo) : 3082 _g1h(G1CollectedHeap::heap()), 3083 _vo(vo), 3084 _failures(false) { } 3085 3086 bool failures() { return _failures; } 3087 3088 template <class T> void do_oop_nv(T* p) { 3089 T heap_oop = oopDesc::load_heap_oop(p); 3090 if (!oopDesc::is_null(heap_oop)) { 3091 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 3092 if (_g1h->is_obj_dead_cond(obj, _vo)) { 3093 gclog_or_tty->print_cr("Root location "PTR_FORMAT" " 3094 "points to dead obj "PTR_FORMAT, p, (void*) obj); 3095 if (_vo == VerifyOption_G1UseMarkWord) { 3096 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark())); 3097 } 3098 obj->print_on(gclog_or_tty); 3099 _failures = true; 3100 } 3101 } 3102 } 3103 3104 void do_oop(oop* p) { do_oop_nv(p); } 3105 void do_oop(narrowOop* p) { do_oop_nv(p); } 3106 }; 3107 3108 class G1VerifyCodeRootOopClosure: public OopClosure { 3109 G1CollectedHeap* _g1h; 3110 OopClosure* _root_cl; 3111 nmethod* _nm; 3112 VerifyOption _vo; 3113 bool _failures; 3114 3115 template <class T> void do_oop_work(T* p) { 3116 // First verify that this root is live 3117 _root_cl->do_oop(p); 3118 3119 if (!G1VerifyHeapRegionCodeRoots) { 3120 // We're not verifying the code roots attached to heap region. 3121 return; 3122 } 3123 3124 // Don't check the code roots during marking verification in a full GC 3125 if (_vo == VerifyOption_G1UseMarkWord) { 3126 return; 3127 } 3128 3129 // Now verify that the current nmethod (which contains p) is 3130 // in the code root list of the heap region containing the 3131 // object referenced by p. 3132 3133 T heap_oop = oopDesc::load_heap_oop(p); 3134 if (!oopDesc::is_null(heap_oop)) { 3135 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 3136 3137 // Now fetch the region containing the object 3138 HeapRegion* hr = _g1h->heap_region_containing(obj); 3139 HeapRegionRemSet* hrrs = hr->rem_set(); 3140 // Verify that the strong code root list for this region 3141 // contains the nmethod 3142 if (!hrrs->strong_code_roots_list_contains(_nm)) { 3143 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" " 3144 "from nmethod "PTR_FORMAT" not in strong " 3145 "code roots for region ["PTR_FORMAT","PTR_FORMAT")", 3146 p, _nm, hr->bottom(), hr->end()); 3147 _failures = true; 3148 } 3149 } 3150 } 3151 3152 public: 3153 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo): 3154 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {} 3155 3156 void do_oop(oop* p) { do_oop_work(p); } 3157 void do_oop(narrowOop* p) { do_oop_work(p); } 3158 3159 void set_nmethod(nmethod* nm) { _nm = nm; } 3160 bool failures() { return _failures; } 3161 }; 3162 3163 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure { 3164 G1VerifyCodeRootOopClosure* _oop_cl; 3165 3166 public: 3167 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl): 3168 _oop_cl(oop_cl) {} 3169 3170 void do_code_blob(CodeBlob* cb) { 3171 nmethod* nm = cb->as_nmethod_or_null(); 3172 if (nm != NULL) { 3173 _oop_cl->set_nmethod(nm); 3174 nm->oops_do(_oop_cl); 3175 } 3176 } 3177 }; 3178 3179 class YoungRefCounterClosure : public OopClosure { 3180 G1CollectedHeap* _g1h; 3181 int _count; 3182 public: 3183 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {} 3184 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } } 3185 void do_oop(narrowOop* p) { ShouldNotReachHere(); } 3186 3187 int count() { return _count; } 3188 void reset_count() { _count = 0; }; 3189 }; 3190 3191 class VerifyKlassClosure: public KlassClosure { 3192 YoungRefCounterClosure _young_ref_counter_closure; 3193 OopClosure *_oop_closure; 3194 public: 3195 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {} 3196 void do_klass(Klass* k) { 3197 k->oops_do(_oop_closure); 3198 3199 _young_ref_counter_closure.reset_count(); 3200 k->oops_do(&_young_ref_counter_closure); 3201 if (_young_ref_counter_closure.count() > 0) { 3202 guarantee(k->has_modified_oops(), err_msg("Klass " PTR_FORMAT ", has young refs but is not dirty.", k)); 3203 } 3204 } 3205 }; 3206 3207 class VerifyLivenessOopClosure: public OopClosure { 3208 G1CollectedHeap* _g1h; 3209 VerifyOption _vo; 3210 public: 3211 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo): 3212 _g1h(g1h), _vo(vo) 3213 { } 3214 void do_oop(narrowOop *p) { do_oop_work(p); } 3215 void do_oop( oop *p) { do_oop_work(p); } 3216 3217 template <class T> void do_oop_work(T *p) { 3218 oop obj = oopDesc::load_decode_heap_oop(p); 3219 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo), 3220 "Dead object referenced by a not dead object"); 3221 } 3222 }; 3223 3224 class VerifyObjsInRegionClosure: public ObjectClosure { 3225 private: 3226 G1CollectedHeap* _g1h; 3227 size_t _live_bytes; 3228 HeapRegion *_hr; 3229 VerifyOption _vo; 3230 public: 3231 // _vo == UsePrevMarking -> use "prev" marking information, 3232 // _vo == UseNextMarking -> use "next" marking information, 3233 // _vo == UseMarkWord -> use mark word from object header. 3234 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo) 3235 : _live_bytes(0), _hr(hr), _vo(vo) { 3236 _g1h = G1CollectedHeap::heap(); 3237 } 3238 void do_object(oop o) { 3239 VerifyLivenessOopClosure isLive(_g1h, _vo); 3240 assert(o != NULL, "Huh?"); 3241 if (!_g1h->is_obj_dead_cond(o, _vo)) { 3242 // If the object is alive according to the mark word, 3243 // then verify that the marking information agrees. 3244 // Note we can't verify the contra-positive of the 3245 // above: if the object is dead (according to the mark 3246 // word), it may not be marked, or may have been marked 3247 // but has since became dead, or may have been allocated 3248 // since the last marking. 3249 if (_vo == VerifyOption_G1UseMarkWord) { 3250 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch"); 3251 } 3252 3253 o->oop_iterate_no_header(&isLive); 3254 if (!_hr->obj_allocated_since_prev_marking(o)) { 3255 size_t obj_size = o->size(); // Make sure we don't overflow 3256 _live_bytes += (obj_size * HeapWordSize); 3257 } 3258 } 3259 } 3260 size_t live_bytes() { return _live_bytes; } 3261 }; 3262 3263 class PrintObjsInRegionClosure : public ObjectClosure { 3264 HeapRegion *_hr; 3265 G1CollectedHeap *_g1; 3266 public: 3267 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) { 3268 _g1 = G1CollectedHeap::heap(); 3269 }; 3270 3271 void do_object(oop o) { 3272 if (o != NULL) { 3273 HeapWord *start = (HeapWord *) o; 3274 size_t word_sz = o->size(); 3275 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT 3276 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n", 3277 (void*) o, word_sz, 3278 _g1->isMarkedPrev(o), 3279 _g1->isMarkedNext(o), 3280 _hr->obj_allocated_since_prev_marking(o)); 3281 HeapWord *end = start + word_sz; 3282 HeapWord *cur; 3283 int *val; 3284 for (cur = start; cur < end; cur++) { 3285 val = (int *) cur; 3286 gclog_or_tty->print("\t "PTR_FORMAT":%d\n", val, *val); 3287 } 3288 } 3289 } 3290 }; 3291 3292 class VerifyRegionClosure: public HeapRegionClosure { 3293 private: 3294 bool _par; 3295 VerifyOption _vo; 3296 bool _failures; 3297 public: 3298 // _vo == UsePrevMarking -> use "prev" marking information, 3299 // _vo == UseNextMarking -> use "next" marking information, 3300 // _vo == UseMarkWord -> use mark word from object header. 3301 VerifyRegionClosure(bool par, VerifyOption vo) 3302 : _par(par), 3303 _vo(vo), 3304 _failures(false) {} 3305 3306 bool failures() { 3307 return _failures; 3308 } 3309 3310 bool doHeapRegion(HeapRegion* r) { 3311 if (!r->continuesHumongous()) { 3312 bool failures = false; 3313 r->verify(_vo, &failures); 3314 if (failures) { 3315 _failures = true; 3316 } else { 3317 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo); 3318 r->object_iterate(¬_dead_yet_cl); 3319 if (_vo != VerifyOption_G1UseNextMarking) { 3320 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) { 3321 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] " 3322 "max_live_bytes "SIZE_FORMAT" " 3323 "< calculated "SIZE_FORMAT, 3324 r->bottom(), r->end(), 3325 r->max_live_bytes(), 3326 not_dead_yet_cl.live_bytes()); 3327 _failures = true; 3328 } 3329 } else { 3330 // When vo == UseNextMarking we cannot currently do a sanity 3331 // check on the live bytes as the calculation has not been 3332 // finalized yet. 3333 } 3334 } 3335 } 3336 return false; // stop the region iteration if we hit a failure 3337 } 3338 }; 3339 3340 // This is the task used for parallel verification of the heap regions 3341 3342 class G1ParVerifyTask: public AbstractGangTask { 3343 private: 3344 G1CollectedHeap* _g1h; 3345 VerifyOption _vo; 3346 bool _failures; 3347 3348 public: 3349 // _vo == UsePrevMarking -> use "prev" marking information, 3350 // _vo == UseNextMarking -> use "next" marking information, 3351 // _vo == UseMarkWord -> use mark word from object header. 3352 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) : 3353 AbstractGangTask("Parallel verify task"), 3354 _g1h(g1h), 3355 _vo(vo), 3356 _failures(false) { } 3357 3358 bool failures() { 3359 return _failures; 3360 } 3361 3362 void work(uint worker_id) { 3363 HandleMark hm; 3364 VerifyRegionClosure blk(true, _vo); 3365 _g1h->heap_region_par_iterate_chunked(&blk, worker_id, 3366 _g1h->workers()->active_workers(), 3367 HeapRegion::ParVerifyClaimValue); 3368 if (blk.failures()) { 3369 _failures = true; 3370 } 3371 } 3372 }; 3373 3374 void G1CollectedHeap::verify(bool silent, VerifyOption vo) { 3375 if (SafepointSynchronize::is_at_safepoint()) { 3376 assert(Thread::current()->is_VM_thread(), 3377 "Expected to be executed serially by the VM thread at this point"); 3378 3379 if (!silent) { gclog_or_tty->print("Roots "); } 3380 VerifyRootsClosure rootsCl(vo); 3381 VerifyKlassClosure klassCl(this, &rootsCl); 3382 3383 // We apply the relevant closures to all the oops in the 3384 // system dictionary, class loader data graph and the string table. 3385 // Don't verify the code cache here, since it's verified below. 3386 const int so = SO_AllClasses | SO_Strings; 3387 3388 // Need cleared claim bits for the strong roots processing 3389 ClassLoaderDataGraph::clear_claimed_marks(); 3390 3391 process_strong_roots(true, // activate StrongRootsScope 3392 ScanningOption(so), // roots scanning options 3393 &rootsCl, 3394 &klassCl 3395 ); 3396 3397 // Verify the nmethods in the code cache. 3398 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo); 3399 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl); 3400 CodeCache::blobs_do(&blobsCl); 3401 3402 bool failures = rootsCl.failures() || codeRootsCl.failures(); 3403 3404 if (vo != VerifyOption_G1UseMarkWord) { 3405 // If we're verifying during a full GC then the region sets 3406 // will have been torn down at the start of the GC. Therefore 3407 // verifying the region sets will fail. So we only verify 3408 // the region sets when not in a full GC. 3409 if (!silent) { gclog_or_tty->print("HeapRegionSets "); } 3410 verify_region_sets(); 3411 } 3412 3413 if (!silent) { gclog_or_tty->print("HeapRegions "); } 3414 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) { 3415 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue), 3416 "sanity check"); 3417 3418 G1ParVerifyTask task(this, vo); 3419 assert(UseDynamicNumberOfGCThreads || 3420 workers()->active_workers() == workers()->total_workers(), 3421 "If not dynamic should be using all the workers"); 3422 int n_workers = workers()->active_workers(); 3423 set_par_threads(n_workers); 3424 workers()->run_task(&task); 3425 set_par_threads(0); 3426 if (task.failures()) { 3427 failures = true; 3428 } 3429 3430 // Checks that the expected amount of parallel work was done. 3431 // The implication is that n_workers is > 0. 3432 assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue), 3433 "sanity check"); 3434 3435 reset_heap_region_claim_values(); 3436 3437 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue), 3438 "sanity check"); 3439 } else { 3440 VerifyRegionClosure blk(false, vo); 3441 heap_region_iterate(&blk); 3442 if (blk.failures()) { 3443 failures = true; 3444 } 3445 } 3446 if (!silent) gclog_or_tty->print("RemSet "); 3447 rem_set()->verify(); 3448 3449 if (G1StringDedup::is_enabled()) { 3450 if (!silent) gclog_or_tty->print("StrDedup "); 3451 G1StringDedup::verify(); 3452 } 3453 3454 if (failures) { 3455 gclog_or_tty->print_cr("Heap:"); 3456 // It helps to have the per-region information in the output to 3457 // help us track down what went wrong. This is why we call 3458 // print_extended_on() instead of print_on(). 3459 print_extended_on(gclog_or_tty); 3460 gclog_or_tty->cr(); 3461 #ifndef PRODUCT 3462 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) { 3463 concurrent_mark()->print_reachable("at-verification-failure", 3464 vo, false /* all */); 3465 } 3466 #endif 3467 gclog_or_tty->flush(); 3468 } 3469 guarantee(!failures, "there should not have been any failures"); 3470 } else { 3471 if (!silent) { 3472 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet"); 3473 if (G1StringDedup::is_enabled()) { 3474 gclog_or_tty->print(", StrDedup"); 3475 } 3476 gclog_or_tty->print(") "); 3477 } 3478 } 3479 } 3480 3481 void G1CollectedHeap::verify(bool silent) { 3482 verify(silent, VerifyOption_G1UsePrevMarking); 3483 } 3484 3485 double G1CollectedHeap::verify(bool guard, const char* msg) { 3486 double verify_time_ms = 0.0; 3487 3488 if (guard && total_collections() >= VerifyGCStartAt) { 3489 double verify_start = os::elapsedTime(); 3490 HandleMark hm; // Discard invalid handles created during verification 3491 prepare_for_verify(); 3492 Universe::verify(VerifyOption_G1UsePrevMarking, msg); 3493 verify_time_ms = (os::elapsedTime() - verify_start) * 1000; 3494 } 3495 3496 return verify_time_ms; 3497 } 3498 3499 void G1CollectedHeap::verify_before_gc() { 3500 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:"); 3501 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms); 3502 } 3503 3504 void G1CollectedHeap::verify_after_gc() { 3505 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:"); 3506 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms); 3507 } 3508 3509 class PrintRegionClosure: public HeapRegionClosure { 3510 outputStream* _st; 3511 public: 3512 PrintRegionClosure(outputStream* st) : _st(st) {} 3513 bool doHeapRegion(HeapRegion* r) { 3514 r->print_on(_st); 3515 return false; 3516 } 3517 }; 3518 3519 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 3520 const HeapRegion* hr, 3521 const VerifyOption vo) const { 3522 switch (vo) { 3523 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); 3524 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); 3525 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked(); 3526 default: ShouldNotReachHere(); 3527 } 3528 return false; // keep some compilers happy 3529 } 3530 3531 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 3532 const VerifyOption vo) const { 3533 switch (vo) { 3534 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); 3535 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); 3536 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked(); 3537 default: ShouldNotReachHere(); 3538 } 3539 return false; // keep some compilers happy 3540 } 3541 3542 void G1CollectedHeap::print_on(outputStream* st) const { 3543 st->print(" %-20s", "garbage-first heap"); 3544 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 3545 capacity()/K, used_unlocked()/K); 3546 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")", 3547 _g1_storage.low_boundary(), 3548 _g1_storage.high(), 3549 _g1_storage.high_boundary()); 3550 st->cr(); 3551 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); 3552 uint young_regions = _young_list->length(); 3553 st->print("%u young (" SIZE_FORMAT "K), ", young_regions, 3554 (size_t) young_regions * HeapRegion::GrainBytes / K); 3555 uint survivor_regions = g1_policy()->recorded_survivor_regions(); 3556 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, 3557 (size_t) survivor_regions * HeapRegion::GrainBytes / K); 3558 st->cr(); 3559 MetaspaceAux::print_on(st); 3560 } 3561 3562 void G1CollectedHeap::print_extended_on(outputStream* st) const { 3563 print_on(st); 3564 3565 // Print the per-region information. 3566 st->cr(); 3567 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), " 3568 "HS=humongous(starts), HC=humongous(continues), " 3569 "CS=collection set, F=free, TS=gc time stamp, " 3570 "PTAMS=previous top-at-mark-start, " 3571 "NTAMS=next top-at-mark-start)"); 3572 PrintRegionClosure blk(st); 3573 heap_region_iterate(&blk); 3574 } 3575 3576 void G1CollectedHeap::print_on_error(outputStream* st) const { 3577 this->CollectedHeap::print_on_error(st); 3578 3579 if (_cm != NULL) { 3580 st->cr(); 3581 _cm->print_on_error(st); 3582 } 3583 } 3584 3585 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const { 3586 if (G1CollectedHeap::use_parallel_gc_threads()) { 3587 workers()->print_worker_threads_on(st); 3588 } 3589 _cmThread->print_on(st); 3590 st->cr(); 3591 _cm->print_worker_threads_on(st); 3592 _cg1r->print_worker_threads_on(st); 3593 if (G1StringDedup::is_enabled()) { 3594 G1StringDedup::print_worker_threads_on(st); 3595 } 3596 } 3597 3598 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { 3599 if (G1CollectedHeap::use_parallel_gc_threads()) { 3600 workers()->threads_do(tc); 3601 } 3602 tc->do_thread(_cmThread); 3603 _cg1r->threads_do(tc); 3604 if (G1StringDedup::is_enabled()) { 3605 G1StringDedup::threads_do(tc); 3606 } 3607 } 3608 3609 void G1CollectedHeap::print_tracing_info() const { 3610 // We'll overload this to mean "trace GC pause statistics." 3611 if (TraceYoungGenTime || TraceOldGenTime) { 3612 // The "G1CollectorPolicy" is keeping track of these stats, so delegate 3613 // to that. 3614 g1_policy()->print_tracing_info(); 3615 } 3616 if (G1SummarizeRSetStats) { 3617 g1_rem_set()->print_summary_info(); 3618 } 3619 if (G1SummarizeConcMark) { 3620 concurrent_mark()->print_summary_info(); 3621 } 3622 g1_policy()->print_yg_surv_rate_info(); 3623 SpecializationStats::print(); 3624 } 3625 3626 #ifndef PRODUCT 3627 // Helpful for debugging RSet issues. 3628 3629 class PrintRSetsClosure : public HeapRegionClosure { 3630 private: 3631 const char* _msg; 3632 size_t _occupied_sum; 3633 3634 public: 3635 bool doHeapRegion(HeapRegion* r) { 3636 HeapRegionRemSet* hrrs = r->rem_set(); 3637 size_t occupied = hrrs->occupied(); 3638 _occupied_sum += occupied; 3639 3640 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT, 3641 HR_FORMAT_PARAMS(r)); 3642 if (occupied == 0) { 3643 gclog_or_tty->print_cr(" RSet is empty"); 3644 } else { 3645 hrrs->print(); 3646 } 3647 gclog_or_tty->print_cr("----------"); 3648 return false; 3649 } 3650 3651 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { 3652 gclog_or_tty->cr(); 3653 gclog_or_tty->print_cr("========================================"); 3654 gclog_or_tty->print_cr("%s", msg); 3655 gclog_or_tty->cr(); 3656 } 3657 3658 ~PrintRSetsClosure() { 3659 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum); 3660 gclog_or_tty->print_cr("========================================"); 3661 gclog_or_tty->cr(); 3662 } 3663 }; 3664 3665 void G1CollectedHeap::print_cset_rsets() { 3666 PrintRSetsClosure cl("Printing CSet RSets"); 3667 collection_set_iterate(&cl); 3668 } 3669 3670 void G1CollectedHeap::print_all_rsets() { 3671 PrintRSetsClosure cl("Printing All RSets");; 3672 heap_region_iterate(&cl); 3673 } 3674 #endif // PRODUCT 3675 3676 G1CollectedHeap* G1CollectedHeap::heap() { 3677 assert(_sh->kind() == CollectedHeap::G1CollectedHeap, 3678 "not a garbage-first heap"); 3679 return _g1h; 3680 } 3681 3682 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) { 3683 // always_do_update_barrier = false; 3684 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 3685 // Fill TLAB's and such 3686 accumulate_statistics_all_tlabs(); 3687 ensure_parsability(true); 3688 3689 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) && 3690 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) { 3691 g1_rem_set()->print_periodic_summary_info("Before GC RS summary"); 3692 } 3693 } 3694 3695 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) { 3696 3697 if (G1SummarizeRSetStats && 3698 (G1SummarizeRSetStatsPeriod > 0) && 3699 // we are at the end of the GC. Total collections has already been increased. 3700 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) { 3701 g1_rem_set()->print_periodic_summary_info("After GC RS summary"); 3702 } 3703 3704 // FIXME: what is this about? 3705 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" 3706 // is set. 3707 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(), 3708 "derived pointer present")); 3709 // always_do_update_barrier = true; 3710 3711 resize_all_tlabs(); 3712 3713 // We have just completed a GC. Update the soft reference 3714 // policy with the new heap occupancy 3715 Universe::update_heap_info_at_gc(); 3716 } 3717 3718 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, 3719 unsigned int gc_count_before, 3720 bool* succeeded, 3721 GCCause::Cause gc_cause) { 3722 assert_heap_not_locked_and_not_at_safepoint(); 3723 g1_policy()->record_stop_world_start(); 3724 VM_G1IncCollectionPause op(gc_count_before, 3725 word_size, 3726 false, /* should_initiate_conc_mark */ 3727 g1_policy()->max_pause_time_ms(), 3728 gc_cause); 3729 VMThread::execute(&op); 3730 3731 HeapWord* result = op.result(); 3732 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded(); 3733 assert(result == NULL || ret_succeeded, 3734 "the result should be NULL if the VM did not succeed"); 3735 *succeeded = ret_succeeded; 3736 3737 assert_heap_not_locked(); 3738 return result; 3739 } 3740 3741 void 3742 G1CollectedHeap::doConcurrentMark() { 3743 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); 3744 if (!_cmThread->in_progress()) { 3745 _cmThread->set_started(); 3746 CGC_lock->notify(); 3747 } 3748 } 3749 3750 size_t G1CollectedHeap::pending_card_num() { 3751 size_t extra_cards = 0; 3752 JavaThread *curr = Threads::first(); 3753 while (curr != NULL) { 3754 DirtyCardQueue& dcq = curr->dirty_card_queue(); 3755 extra_cards += dcq.size(); 3756 curr = curr->next(); 3757 } 3758 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 3759 size_t buffer_size = dcqs.buffer_size(); 3760 size_t buffer_num = dcqs.completed_buffers_num(); 3761 3762 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes 3763 // in bytes - not the number of 'entries'. We need to convert 3764 // into a number of cards. 3765 return (buffer_size * buffer_num + extra_cards) / oopSize; 3766 } 3767 3768 size_t G1CollectedHeap::cards_scanned() { 3769 return g1_rem_set()->cardsScanned(); 3770 } 3771 3772 void 3773 G1CollectedHeap::setup_surviving_young_words() { 3774 assert(_surviving_young_words == NULL, "pre-condition"); 3775 uint array_length = g1_policy()->young_cset_region_length(); 3776 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC); 3777 if (_surviving_young_words == NULL) { 3778 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR, 3779 "Not enough space for young surv words summary."); 3780 } 3781 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t)); 3782 #ifdef ASSERT 3783 for (uint i = 0; i < array_length; ++i) { 3784 assert( _surviving_young_words[i] == 0, "memset above" ); 3785 } 3786 #endif // !ASSERT 3787 } 3788 3789 void 3790 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) { 3791 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); 3792 uint array_length = g1_policy()->young_cset_region_length(); 3793 for (uint i = 0; i < array_length; ++i) { 3794 _surviving_young_words[i] += surv_young_words[i]; 3795 } 3796 } 3797 3798 void 3799 G1CollectedHeap::cleanup_surviving_young_words() { 3800 guarantee( _surviving_young_words != NULL, "pre-condition" ); 3801 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words, mtGC); 3802 _surviving_young_words = NULL; 3803 } 3804 3805 #ifdef ASSERT 3806 class VerifyCSetClosure: public HeapRegionClosure { 3807 public: 3808 bool doHeapRegion(HeapRegion* hr) { 3809 // Here we check that the CSet region's RSet is ready for parallel 3810 // iteration. The fields that we'll verify are only manipulated 3811 // when the region is part of a CSet and is collected. Afterwards, 3812 // we reset these fields when we clear the region's RSet (when the 3813 // region is freed) so they are ready when the region is 3814 // re-allocated. The only exception to this is if there's an 3815 // evacuation failure and instead of freeing the region we leave 3816 // it in the heap. In that case, we reset these fields during 3817 // evacuation failure handling. 3818 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification"); 3819 3820 // Here's a good place to add any other checks we'd like to 3821 // perform on CSet regions. 3822 return false; 3823 } 3824 }; 3825 #endif // ASSERT 3826 3827 #if TASKQUEUE_STATS 3828 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) { 3829 st->print_raw_cr("GC Task Stats"); 3830 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); 3831 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); 3832 } 3833 3834 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const { 3835 print_taskqueue_stats_hdr(st); 3836 3837 TaskQueueStats totals; 3838 const int n = workers() != NULL ? workers()->total_workers() : 1; 3839 for (int i = 0; i < n; ++i) { 3840 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr(); 3841 totals += task_queue(i)->stats; 3842 } 3843 st->print_raw("tot "); totals.print(st); st->cr(); 3844 3845 DEBUG_ONLY(totals.verify()); 3846 } 3847 3848 void G1CollectedHeap::reset_taskqueue_stats() { 3849 const int n = workers() != NULL ? workers()->total_workers() : 1; 3850 for (int i = 0; i < n; ++i) { 3851 task_queue(i)->stats.reset(); 3852 } 3853 } 3854 #endif // TASKQUEUE_STATS 3855 3856 void G1CollectedHeap::log_gc_header() { 3857 if (!G1Log::fine()) { 3858 return; 3859 } 3860 3861 gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id()); 3862 3863 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause()) 3864 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)") 3865 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : ""); 3866 3867 gclog_or_tty->print("[%s", (const char*)gc_cause_str); 3868 } 3869 3870 void G1CollectedHeap::log_gc_footer(double pause_time_sec) { 3871 if (!G1Log::fine()) { 3872 return; 3873 } 3874 3875 if (G1Log::finer()) { 3876 if (evacuation_failed()) { 3877 gclog_or_tty->print(" (to-space exhausted)"); 3878 } 3879 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec); 3880 g1_policy()->phase_times()->note_gc_end(); 3881 g1_policy()->phase_times()->print(pause_time_sec); 3882 g1_policy()->print_detailed_heap_transition(); 3883 } else { 3884 if (evacuation_failed()) { 3885 gclog_or_tty->print("--"); 3886 } 3887 g1_policy()->print_heap_transition(); 3888 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec); 3889 } 3890 gclog_or_tty->flush(); 3891 } 3892 3893 bool 3894 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { 3895 assert_at_safepoint(true /* should_be_vm_thread */); 3896 guarantee(!is_gc_active(), "collection is not reentrant"); 3897 3898 if (GC_locker::check_active_before_gc()) { 3899 return false; 3900 } 3901 3902 _gc_timer_stw->register_gc_start(); 3903 3904 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start()); 3905 3906 SvcGCMarker sgcm(SvcGCMarker::MINOR); 3907 ResourceMark rm; 3908 3909 print_heap_before_gc(); 3910 trace_heap_before_gc(_gc_tracer_stw); 3911 3912 verify_region_sets_optional(); 3913 verify_dirty_young_regions(); 3914 3915 // This call will decide whether this pause is an initial-mark 3916 // pause. If it is, during_initial_mark_pause() will return true 3917 // for the duration of this pause. 3918 g1_policy()->decide_on_conc_mark_initiation(); 3919 3920 // We do not allow initial-mark to be piggy-backed on a mixed GC. 3921 assert(!g1_policy()->during_initial_mark_pause() || 3922 g1_policy()->gcs_are_young(), "sanity"); 3923 3924 // We also do not allow mixed GCs during marking. 3925 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity"); 3926 3927 // Record whether this pause is an initial mark. When the current 3928 // thread has completed its logging output and it's safe to signal 3929 // the CM thread, the flag's value in the policy has been reset. 3930 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause(); 3931 3932 // Inner scope for scope based logging, timers, and stats collection 3933 { 3934 EvacuationInfo evacuation_info; 3935 3936 if (g1_policy()->during_initial_mark_pause()) { 3937 // We are about to start a marking cycle, so we increment the 3938 // full collection counter. 3939 increment_old_marking_cycles_started(); 3940 register_concurrent_cycle_start(_gc_timer_stw->gc_start()); 3941 } 3942 3943 _gc_tracer_stw->report_yc_type(yc_type()); 3944 3945 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty); 3946 3947 int active_workers = (G1CollectedHeap::use_parallel_gc_threads() ? 3948 workers()->active_workers() : 1); 3949 double pause_start_sec = os::elapsedTime(); 3950 g1_policy()->phase_times()->note_gc_start(active_workers); 3951 log_gc_header(); 3952 3953 TraceCollectorStats tcs(g1mm()->incremental_collection_counters()); 3954 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause()); 3955 3956 // If the secondary_free_list is not empty, append it to the 3957 // free_list. No need to wait for the cleanup operation to finish; 3958 // the region allocation code will check the secondary_free_list 3959 // and wait if necessary. If the G1StressConcRegionFreeing flag is 3960 // set, skip this step so that the region allocation code has to 3961 // get entries from the secondary_free_list. 3962 if (!G1StressConcRegionFreeing) { 3963 append_secondary_free_list_if_not_empty_with_lock(); 3964 } 3965 3966 assert(check_young_list_well_formed(), "young list should be well formed"); 3967 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue), 3968 "sanity check"); 3969 3970 // Don't dynamically change the number of GC threads this early. A value of 3971 // 0 is used to indicate serial work. When parallel work is done, 3972 // it will be set. 3973 3974 { // Call to jvmpi::post_class_unload_events must occur outside of active GC 3975 IsGCActiveMark x; 3976 3977 gc_prologue(false); 3978 increment_total_collections(false /* full gc */); 3979 increment_gc_time_stamp(); 3980 3981 verify_before_gc(); 3982 check_bitmaps("GC Start"); 3983 3984 COMPILER2_PRESENT(DerivedPointerTable::clear()); 3985 3986 // Please see comment in g1CollectedHeap.hpp and 3987 // G1CollectedHeap::ref_processing_init() to see how 3988 // reference processing currently works in G1. 3989 3990 // Enable discovery in the STW reference processor 3991 ref_processor_stw()->enable_discovery(true /*verify_disabled*/, 3992 true /*verify_no_refs*/); 3993 3994 { 3995 // We want to temporarily turn off discovery by the 3996 // CM ref processor, if necessary, and turn it back on 3997 // on again later if we do. Using a scoped 3998 // NoRefDiscovery object will do this. 3999 NoRefDiscovery no_cm_discovery(ref_processor_cm()); 4000 4001 // Forget the current alloc region (we might even choose it to be part 4002 // of the collection set!). 4003 release_mutator_alloc_region(); 4004 4005 // We should call this after we retire the mutator alloc 4006 // region(s) so that all the ALLOC / RETIRE events are generated 4007 // before the start GC event. 4008 _hr_printer.start_gc(false /* full */, (size_t) total_collections()); 4009 4010 // This timing is only used by the ergonomics to handle our pause target. 4011 // It is unclear why this should not include the full pause. We will 4012 // investigate this in CR 7178365. 4013 // 4014 // Preserving the old comment here if that helps the investigation: 4015 // 4016 // The elapsed time induced by the start time below deliberately elides 4017 // the possible verification above. 4018 double sample_start_time_sec = os::elapsedTime(); 4019 4020 #if YOUNG_LIST_VERBOSE 4021 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:"); 4022 _young_list->print(); 4023 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 4024 #endif // YOUNG_LIST_VERBOSE 4025 4026 g1_policy()->record_collection_pause_start(sample_start_time_sec); 4027 4028 double scan_wait_start = os::elapsedTime(); 4029 // We have to wait until the CM threads finish scanning the 4030 // root regions as it's the only way to ensure that all the 4031 // objects on them have been correctly scanned before we start 4032 // moving them during the GC. 4033 bool waited = _cm->root_regions()->wait_until_scan_finished(); 4034 double wait_time_ms = 0.0; 4035 if (waited) { 4036 double scan_wait_end = os::elapsedTime(); 4037 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0; 4038 } 4039 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms); 4040 4041 #if YOUNG_LIST_VERBOSE 4042 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:"); 4043 _young_list->print(); 4044 #endif // YOUNG_LIST_VERBOSE 4045 4046 if (g1_policy()->during_initial_mark_pause()) { 4047 concurrent_mark()->checkpointRootsInitialPre(); 4048 } 4049 4050 #if YOUNG_LIST_VERBOSE 4051 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:"); 4052 _young_list->print(); 4053 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 4054 #endif // YOUNG_LIST_VERBOSE 4055 4056 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info); 4057 4058 _cm->note_start_of_gc(); 4059 // We should not verify the per-thread SATB buffers given that 4060 // we have not filtered them yet (we'll do so during the 4061 // GC). We also call this after finalize_cset() to 4062 // ensure that the CSet has been finalized. 4063 _cm->verify_no_cset_oops(true /* verify_stacks */, 4064 true /* verify_enqueued_buffers */, 4065 false /* verify_thread_buffers */, 4066 true /* verify_fingers */); 4067 4068 if (_hr_printer.is_active()) { 4069 HeapRegion* hr = g1_policy()->collection_set(); 4070 while (hr != NULL) { 4071 G1HRPrinter::RegionType type; 4072 if (!hr->is_young()) { 4073 type = G1HRPrinter::Old; 4074 } else if (hr->is_survivor()) { 4075 type = G1HRPrinter::Survivor; 4076 } else { 4077 type = G1HRPrinter::Eden; 4078 } 4079 _hr_printer.cset(hr); 4080 hr = hr->next_in_collection_set(); 4081 } 4082 } 4083 4084 #ifdef ASSERT 4085 VerifyCSetClosure cl; 4086 collection_set_iterate(&cl); 4087 #endif // ASSERT 4088 4089 setup_surviving_young_words(); 4090 4091 // Initialize the GC alloc regions. 4092 init_gc_alloc_regions(evacuation_info); 4093 4094 // Actually do the work... 4095 evacuate_collection_set(evacuation_info); 4096 4097 // We do this to mainly verify the per-thread SATB buffers 4098 // (which have been filtered by now) since we didn't verify 4099 // them earlier. No point in re-checking the stacks / enqueued 4100 // buffers given that the CSet has not changed since last time 4101 // we checked. 4102 _cm->verify_no_cset_oops(false /* verify_stacks */, 4103 false /* verify_enqueued_buffers */, 4104 true /* verify_thread_buffers */, 4105 true /* verify_fingers */); 4106 4107 free_collection_set(g1_policy()->collection_set(), evacuation_info); 4108 g1_policy()->clear_collection_set(); 4109 4110 cleanup_surviving_young_words(); 4111 4112 // Start a new incremental collection set for the next pause. 4113 g1_policy()->start_incremental_cset_building(); 4114 4115 clear_cset_fast_test(); 4116 4117 _young_list->reset_sampled_info(); 4118 4119 // Don't check the whole heap at this point as the 4120 // GC alloc regions from this pause have been tagged 4121 // as survivors and moved on to the survivor list. 4122 // Survivor regions will fail the !is_young() check. 4123 assert(check_young_list_empty(false /* check_heap */), 4124 "young list should be empty"); 4125 4126 #if YOUNG_LIST_VERBOSE 4127 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:"); 4128 _young_list->print(); 4129 #endif // YOUNG_LIST_VERBOSE 4130 4131 g1_policy()->record_survivor_regions(_young_list->survivor_length(), 4132 _young_list->first_survivor_region(), 4133 _young_list->last_survivor_region()); 4134 4135 _young_list->reset_auxilary_lists(); 4136 4137 if (evacuation_failed()) { 4138 _summary_bytes_used = recalculate_used(); 4139 uint n_queues = MAX2((int)ParallelGCThreads, 1); 4140 for (uint i = 0; i < n_queues; i++) { 4141 if (_evacuation_failed_info_array[i].has_failed()) { 4142 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]); 4143 } 4144 } 4145 } else { 4146 // The "used" of the the collection set have already been subtracted 4147 // when they were freed. Add in the bytes evacuated. 4148 _summary_bytes_used += g1_policy()->bytes_copied_during_gc(); 4149 } 4150 4151 if (g1_policy()->during_initial_mark_pause()) { 4152 // We have to do this before we notify the CM threads that 4153 // they can start working to make sure that all the 4154 // appropriate initialization is done on the CM object. 4155 concurrent_mark()->checkpointRootsInitialPost(); 4156 set_marking_started(); 4157 // Note that we don't actually trigger the CM thread at 4158 // this point. We do that later when we're sure that 4159 // the current thread has completed its logging output. 4160 } 4161 4162 allocate_dummy_regions(); 4163 4164 #if YOUNG_LIST_VERBOSE 4165 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:"); 4166 _young_list->print(); 4167 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 4168 #endif // YOUNG_LIST_VERBOSE 4169 4170 init_mutator_alloc_region(); 4171 4172 { 4173 size_t expand_bytes = g1_policy()->expansion_amount(); 4174 if (expand_bytes > 0) { 4175 size_t bytes_before = capacity(); 4176 // No need for an ergo verbose message here, 4177 // expansion_amount() does this when it returns a value > 0. 4178 if (!expand(expand_bytes)) { 4179 // We failed to expand the heap so let's verify that 4180 // committed/uncommitted amount match the backing store 4181 assert(capacity() == _g1_storage.committed_size(), "committed size mismatch"); 4182 assert(max_capacity() == _g1_storage.reserved_size(), "reserved size mismatch"); 4183 } 4184 } 4185 } 4186 4187 // We redo the verification but now wrt to the new CSet which 4188 // has just got initialized after the previous CSet was freed. 4189 _cm->verify_no_cset_oops(true /* verify_stacks */, 4190 true /* verify_enqueued_buffers */, 4191 true /* verify_thread_buffers */, 4192 true /* verify_fingers */); 4193 _cm->note_end_of_gc(); 4194 4195 // This timing is only used by the ergonomics to handle our pause target. 4196 // It is unclear why this should not include the full pause. We will 4197 // investigate this in CR 7178365. 4198 double sample_end_time_sec = os::elapsedTime(); 4199 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; 4200 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info); 4201 4202 MemoryService::track_memory_usage(); 4203 4204 // In prepare_for_verify() below we'll need to scan the deferred 4205 // update buffers to bring the RSets up-to-date if 4206 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning 4207 // the update buffers we'll probably need to scan cards on the 4208 // regions we just allocated to (i.e., the GC alloc 4209 // regions). However, during the last GC we called 4210 // set_saved_mark() on all the GC alloc regions, so card 4211 // scanning might skip the [saved_mark_word()...top()] area of 4212 // those regions (i.e., the area we allocated objects into 4213 // during the last GC). But it shouldn't. Given that 4214 // saved_mark_word() is conditional on whether the GC time stamp 4215 // on the region is current or not, by incrementing the GC time 4216 // stamp here we invalidate all the GC time stamps on all the 4217 // regions and saved_mark_word() will simply return top() for 4218 // all the regions. This is a nicer way of ensuring this rather 4219 // than iterating over the regions and fixing them. In fact, the 4220 // GC time stamp increment here also ensures that 4221 // saved_mark_word() will return top() between pauses, i.e., 4222 // during concurrent refinement. So we don't need the 4223 // is_gc_active() check to decided which top to use when 4224 // scanning cards (see CR 7039627). 4225 increment_gc_time_stamp(); 4226 4227 verify_after_gc(); 4228 check_bitmaps("GC End"); 4229 4230 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 4231 ref_processor_stw()->verify_no_references_recorded(); 4232 4233 // CM reference discovery will be re-enabled if necessary. 4234 } 4235 4236 // We should do this after we potentially expand the heap so 4237 // that all the COMMIT events are generated before the end GC 4238 // event, and after we retire the GC alloc regions so that all 4239 // RETIRE events are generated before the end GC event. 4240 _hr_printer.end_gc(false /* full */, (size_t) total_collections()); 4241 4242 if (mark_in_progress()) { 4243 concurrent_mark()->update_g1_committed(); 4244 } 4245 4246 #ifdef TRACESPINNING 4247 ParallelTaskTerminator::print_termination_counts(); 4248 #endif 4249 4250 gc_epilogue(false); 4251 } 4252 4253 // Print the remainder of the GC log output. 4254 log_gc_footer(os::elapsedTime() - pause_start_sec); 4255 4256 // It is not yet to safe to tell the concurrent mark to 4257 // start as we have some optional output below. We don't want the 4258 // output from the concurrent mark thread interfering with this 4259 // logging output either. 4260 4261 _hrs.verify_optional(); 4262 verify_region_sets_optional(); 4263 4264 TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats()); 4265 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); 4266 4267 print_heap_after_gc(); 4268 trace_heap_after_gc(_gc_tracer_stw); 4269 4270 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 4271 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 4272 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 4273 // before any GC notifications are raised. 4274 g1mm()->update_sizes(); 4275 4276 _gc_tracer_stw->report_evacuation_info(&evacuation_info); 4277 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold()); 4278 _gc_timer_stw->register_gc_end(); 4279 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions()); 4280 } 4281 // It should now be safe to tell the concurrent mark thread to start 4282 // without its logging output interfering with the logging output 4283 // that came from the pause. 4284 4285 if (should_start_conc_mark) { 4286 // CAUTION: after the doConcurrentMark() call below, 4287 // the concurrent marking thread(s) could be running 4288 // concurrently with us. Make sure that anything after 4289 // this point does not assume that we are the only GC thread 4290 // running. Note: of course, the actual marking work will 4291 // not start until the safepoint itself is released in 4292 // SuspendibleThreadSet::desynchronize(). 4293 doConcurrentMark(); 4294 } 4295 4296 return true; 4297 } 4298 4299 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose) 4300 { 4301 size_t gclab_word_size; 4302 switch (purpose) { 4303 case GCAllocForSurvived: 4304 gclab_word_size = _survivor_plab_stats.desired_plab_sz(); 4305 break; 4306 case GCAllocForTenured: 4307 gclab_word_size = _old_plab_stats.desired_plab_sz(); 4308 break; 4309 default: 4310 assert(false, "unknown GCAllocPurpose"); 4311 gclab_word_size = _old_plab_stats.desired_plab_sz(); 4312 break; 4313 } 4314 4315 // Prevent humongous PLAB sizes for two reasons: 4316 // * PLABs are allocated using a similar paths as oops, but should 4317 // never be in a humongous region 4318 // * Allowing humongous PLABs needlessly churns the region free lists 4319 return MIN2(_humongous_object_threshold_in_words, gclab_word_size); 4320 } 4321 4322 void G1CollectedHeap::init_mutator_alloc_region() { 4323 assert(_mutator_alloc_region.get() == NULL, "pre-condition"); 4324 _mutator_alloc_region.init(); 4325 } 4326 4327 void G1CollectedHeap::release_mutator_alloc_region() { 4328 _mutator_alloc_region.release(); 4329 assert(_mutator_alloc_region.get() == NULL, "post-condition"); 4330 } 4331 4332 void G1CollectedHeap::init_gc_alloc_regions(EvacuationInfo& evacuation_info) { 4333 assert_at_safepoint(true /* should_be_vm_thread */); 4334 4335 _survivor_gc_alloc_region.init(); 4336 _old_gc_alloc_region.init(); 4337 HeapRegion* retained_region = _retained_old_gc_alloc_region; 4338 _retained_old_gc_alloc_region = NULL; 4339 4340 // We will discard the current GC alloc region if: 4341 // a) it's in the collection set (it can happen!), 4342 // b) it's already full (no point in using it), 4343 // c) it's empty (this means that it was emptied during 4344 // a cleanup and it should be on the free list now), or 4345 // d) it's humongous (this means that it was emptied 4346 // during a cleanup and was added to the free list, but 4347 // has been subsequently used to allocate a humongous 4348 // object that may be less than the region size). 4349 if (retained_region != NULL && 4350 !retained_region->in_collection_set() && 4351 !(retained_region->top() == retained_region->end()) && 4352 !retained_region->is_empty() && 4353 !retained_region->isHumongous()) { 4354 retained_region->set_saved_mark(); 4355 // The retained region was added to the old region set when it was 4356 // retired. We have to remove it now, since we don't allow regions 4357 // we allocate to in the region sets. We'll re-add it later, when 4358 // it's retired again. 4359 _old_set.remove(retained_region); 4360 bool during_im = g1_policy()->during_initial_mark_pause(); 4361 retained_region->note_start_of_copying(during_im); 4362 _old_gc_alloc_region.set(retained_region); 4363 _hr_printer.reuse(retained_region); 4364 evacuation_info.set_alloc_regions_used_before(retained_region->used()); 4365 } 4366 } 4367 4368 void G1CollectedHeap::release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info) { 4369 evacuation_info.set_allocation_regions(_survivor_gc_alloc_region.count() + 4370 _old_gc_alloc_region.count()); 4371 _survivor_gc_alloc_region.release(); 4372 // If we have an old GC alloc region to release, we'll save it in 4373 // _retained_old_gc_alloc_region. If we don't 4374 // _retained_old_gc_alloc_region will become NULL. This is what we 4375 // want either way so no reason to check explicitly for either 4376 // condition. 4377 _retained_old_gc_alloc_region = _old_gc_alloc_region.release(); 4378 4379 if (ResizePLAB) { 4380 _survivor_plab_stats.adjust_desired_plab_sz(no_of_gc_workers); 4381 _old_plab_stats.adjust_desired_plab_sz(no_of_gc_workers); 4382 } 4383 } 4384 4385 void G1CollectedHeap::abandon_gc_alloc_regions() { 4386 assert(_survivor_gc_alloc_region.get() == NULL, "pre-condition"); 4387 assert(_old_gc_alloc_region.get() == NULL, "pre-condition"); 4388 _retained_old_gc_alloc_region = NULL; 4389 } 4390 4391 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) { 4392 _drain_in_progress = false; 4393 set_evac_failure_closure(cl); 4394 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true); 4395 } 4396 4397 void G1CollectedHeap::finalize_for_evac_failure() { 4398 assert(_evac_failure_scan_stack != NULL && 4399 _evac_failure_scan_stack->length() == 0, 4400 "Postcondition"); 4401 assert(!_drain_in_progress, "Postcondition"); 4402 delete _evac_failure_scan_stack; 4403 _evac_failure_scan_stack = NULL; 4404 } 4405 4406 void G1CollectedHeap::remove_self_forwarding_pointers() { 4407 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity"); 4408 4409 double remove_self_forwards_start = os::elapsedTime(); 4410 4411 G1ParRemoveSelfForwardPtrsTask rsfp_task(this); 4412 4413 if (G1CollectedHeap::use_parallel_gc_threads()) { 4414 set_par_threads(); 4415 workers()->run_task(&rsfp_task); 4416 set_par_threads(0); 4417 } else { 4418 rsfp_task.work(0); 4419 } 4420 4421 assert(check_cset_heap_region_claim_values(HeapRegion::ParEvacFailureClaimValue), "sanity"); 4422 4423 // Reset the claim values in the regions in the collection set. 4424 reset_cset_heap_region_claim_values(); 4425 4426 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity"); 4427 4428 // Now restore saved marks, if any. 4429 assert(_objs_with_preserved_marks.size() == 4430 _preserved_marks_of_objs.size(), "Both or none."); 4431 while (!_objs_with_preserved_marks.is_empty()) { 4432 oop obj = _objs_with_preserved_marks.pop(); 4433 markOop m = _preserved_marks_of_objs.pop(); 4434 obj->set_mark(m); 4435 } 4436 _objs_with_preserved_marks.clear(true); 4437 _preserved_marks_of_objs.clear(true); 4438 4439 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0); 4440 } 4441 4442 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) { 4443 _evac_failure_scan_stack->push(obj); 4444 } 4445 4446 void G1CollectedHeap::drain_evac_failure_scan_stack() { 4447 assert(_evac_failure_scan_stack != NULL, "precondition"); 4448 4449 while (_evac_failure_scan_stack->length() > 0) { 4450 oop obj = _evac_failure_scan_stack->pop(); 4451 _evac_failure_closure->set_region(heap_region_containing(obj)); 4452 obj->oop_iterate_backwards(_evac_failure_closure); 4453 } 4454 } 4455 4456 oop 4457 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state, 4458 oop old) { 4459 assert(obj_in_cs(old), 4460 err_msg("obj: "PTR_FORMAT" should still be in the CSet", 4461 (HeapWord*) old)); 4462 markOop m = old->mark(); 4463 oop forward_ptr = old->forward_to_atomic(old); 4464 if (forward_ptr == NULL) { 4465 // Forward-to-self succeeded. 4466 assert(_par_scan_state != NULL, "par scan state"); 4467 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure(); 4468 uint queue_num = _par_scan_state->queue_num(); 4469 4470 _evacuation_failed = true; 4471 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size()); 4472 if (_evac_failure_closure != cl) { 4473 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag); 4474 assert(!_drain_in_progress, 4475 "Should only be true while someone holds the lock."); 4476 // Set the global evac-failure closure to the current thread's. 4477 assert(_evac_failure_closure == NULL, "Or locking has failed."); 4478 set_evac_failure_closure(cl); 4479 // Now do the common part. 4480 handle_evacuation_failure_common(old, m); 4481 // Reset to NULL. 4482 set_evac_failure_closure(NULL); 4483 } else { 4484 // The lock is already held, and this is recursive. 4485 assert(_drain_in_progress, "This should only be the recursive case."); 4486 handle_evacuation_failure_common(old, m); 4487 } 4488 return old; 4489 } else { 4490 // Forward-to-self failed. Either someone else managed to allocate 4491 // space for this object (old != forward_ptr) or they beat us in 4492 // self-forwarding it (old == forward_ptr). 4493 assert(old == forward_ptr || !obj_in_cs(forward_ptr), 4494 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" " 4495 "should not be in the CSet", 4496 (HeapWord*) old, (HeapWord*) forward_ptr)); 4497 return forward_ptr; 4498 } 4499 } 4500 4501 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) { 4502 preserve_mark_if_necessary(old, m); 4503 4504 HeapRegion* r = heap_region_containing(old); 4505 if (!r->evacuation_failed()) { 4506 r->set_evacuation_failed(true); 4507 _hr_printer.evac_failure(r); 4508 } 4509 4510 push_on_evac_failure_scan_stack(old); 4511 4512 if (!_drain_in_progress) { 4513 // prevent recursion in copy_to_survivor_space() 4514 _drain_in_progress = true; 4515 drain_evac_failure_scan_stack(); 4516 _drain_in_progress = false; 4517 } 4518 } 4519 4520 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) { 4521 assert(evacuation_failed(), "Oversaving!"); 4522 // We want to call the "for_promotion_failure" version only in the 4523 // case of a promotion failure. 4524 if (m->must_be_preserved_for_promotion_failure(obj)) { 4525 _objs_with_preserved_marks.push(obj); 4526 _preserved_marks_of_objs.push(m); 4527 } 4528 } 4529 4530 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose, 4531 size_t word_size) { 4532 if (purpose == GCAllocForSurvived) { 4533 HeapWord* result = survivor_attempt_allocation(word_size); 4534 if (result != NULL) { 4535 return result; 4536 } else { 4537 // Let's try to allocate in the old gen in case we can fit the 4538 // object there. 4539 return old_attempt_allocation(word_size); 4540 } 4541 } else { 4542 assert(purpose == GCAllocForTenured, "sanity"); 4543 HeapWord* result = old_attempt_allocation(word_size); 4544 if (result != NULL) { 4545 return result; 4546 } else { 4547 // Let's try to allocate in the survivors in case we can fit the 4548 // object there. 4549 return survivor_attempt_allocation(word_size); 4550 } 4551 } 4552 4553 ShouldNotReachHere(); 4554 // Trying to keep some compilers happy. 4555 return NULL; 4556 } 4557 4558 G1ParGCAllocBuffer::G1ParGCAllocBuffer(size_t gclab_word_size) : 4559 ParGCAllocBuffer(gclab_word_size), _retired(true) { } 4560 4561 void G1ParCopyHelper::mark_object(oop obj) { 4562 assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet"); 4563 4564 // We know that the object is not moving so it's safe to read its size. 4565 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id); 4566 } 4567 4568 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) { 4569 assert(from_obj->is_forwarded(), "from obj should be forwarded"); 4570 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee"); 4571 assert(from_obj != to_obj, "should not be self-forwarded"); 4572 4573 assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet"); 4574 assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet"); 4575 4576 // The object might be in the process of being copied by another 4577 // worker so we cannot trust that its to-space image is 4578 // well-formed. So we have to read its size from its from-space 4579 // image which we know should not be changing. 4580 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id); 4581 } 4582 4583 template <class T> 4584 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) { 4585 if (_g1->heap_region_containing_raw(new_obj)->is_young()) { 4586 _scanned_klass->record_modified_oops(); 4587 } 4588 } 4589 4590 template <G1Barrier barrier, bool do_mark_object> 4591 template <class T> 4592 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) { 4593 T heap_oop = oopDesc::load_heap_oop(p); 4594 4595 if (oopDesc::is_null(heap_oop)) { 4596 return; 4597 } 4598 4599 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 4600 4601 assert(_worker_id == _par_scan_state->queue_num(), "sanity"); 4602 4603 if (_g1->in_cset_fast_test(obj)) { 4604 oop forwardee; 4605 if (obj->is_forwarded()) { 4606 forwardee = obj->forwardee(); 4607 } else { 4608 forwardee = _par_scan_state->copy_to_survivor_space(obj); 4609 } 4610 assert(forwardee != NULL, "forwardee should not be NULL"); 4611 oopDesc::encode_store_heap_oop(p, forwardee); 4612 if (do_mark_object && forwardee != obj) { 4613 // If the object is self-forwarded we don't need to explicitly 4614 // mark it, the evacuation failure protocol will do so. 4615 mark_forwarded_object(obj, forwardee); 4616 } 4617 4618 if (barrier == G1BarrierKlass) { 4619 do_klass_barrier(p, forwardee); 4620 } 4621 } else { 4622 // The object is not in collection set. If we're a root scanning 4623 // closure during an initial mark pause (i.e. do_mark_object will 4624 // be true) then attempt to mark the object. 4625 if (do_mark_object) { 4626 mark_object(obj); 4627 } 4628 } 4629 4630 if (barrier == G1BarrierEvac) { 4631 _par_scan_state->update_rs(_from, p, _worker_id); 4632 } 4633 } 4634 4635 template void G1ParCopyClosure<G1BarrierEvac, false>::do_oop_work(oop* p); 4636 template void G1ParCopyClosure<G1BarrierEvac, false>::do_oop_work(narrowOop* p); 4637 4638 class G1ParEvacuateFollowersClosure : public VoidClosure { 4639 protected: 4640 G1CollectedHeap* _g1h; 4641 G1ParScanThreadState* _par_scan_state; 4642 RefToScanQueueSet* _queues; 4643 ParallelTaskTerminator* _terminator; 4644 4645 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 4646 RefToScanQueueSet* queues() { return _queues; } 4647 ParallelTaskTerminator* terminator() { return _terminator; } 4648 4649 public: 4650 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h, 4651 G1ParScanThreadState* par_scan_state, 4652 RefToScanQueueSet* queues, 4653 ParallelTaskTerminator* terminator) 4654 : _g1h(g1h), _par_scan_state(par_scan_state), 4655 _queues(queues), _terminator(terminator) {} 4656 4657 void do_void(); 4658 4659 private: 4660 inline bool offer_termination(); 4661 }; 4662 4663 bool G1ParEvacuateFollowersClosure::offer_termination() { 4664 G1ParScanThreadState* const pss = par_scan_state(); 4665 pss->start_term_time(); 4666 const bool res = terminator()->offer_termination(); 4667 pss->end_term_time(); 4668 return res; 4669 } 4670 4671 void G1ParEvacuateFollowersClosure::do_void() { 4672 G1ParScanThreadState* const pss = par_scan_state(); 4673 pss->trim_queue(); 4674 do { 4675 pss->steal_and_trim_queue(queues()); 4676 } while (!offer_termination()); 4677 } 4678 4679 class G1KlassScanClosure : public KlassClosure { 4680 G1ParCopyHelper* _closure; 4681 bool _process_only_dirty; 4682 int _count; 4683 public: 4684 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty) 4685 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {} 4686 void do_klass(Klass* klass) { 4687 // If the klass has not been dirtied we know that there's 4688 // no references into the young gen and we can skip it. 4689 if (!_process_only_dirty || klass->has_modified_oops()) { 4690 // Clean the klass since we're going to scavenge all the metadata. 4691 klass->clear_modified_oops(); 4692 4693 // Tell the closure that this klass is the Klass to scavenge 4694 // and is the one to dirty if oops are left pointing into the young gen. 4695 _closure->set_scanned_klass(klass); 4696 4697 klass->oops_do(_closure); 4698 4699 _closure->set_scanned_klass(NULL); 4700 } 4701 _count++; 4702 } 4703 }; 4704 4705 class G1ParTask : public AbstractGangTask { 4706 protected: 4707 G1CollectedHeap* _g1h; 4708 RefToScanQueueSet *_queues; 4709 ParallelTaskTerminator _terminator; 4710 uint _n_workers; 4711 4712 Mutex _stats_lock; 4713 Mutex* stats_lock() { return &_stats_lock; } 4714 4715 size_t getNCards() { 4716 return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1) 4717 / G1BlockOffsetSharedArray::N_bytes; 4718 } 4719 4720 public: 4721 G1ParTask(G1CollectedHeap* g1h, RefToScanQueueSet *task_queues) 4722 : AbstractGangTask("G1 collection"), 4723 _g1h(g1h), 4724 _queues(task_queues), 4725 _terminator(0, _queues), 4726 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true) 4727 {} 4728 4729 RefToScanQueueSet* queues() { return _queues; } 4730 4731 RefToScanQueue *work_queue(int i) { 4732 return queues()->queue(i); 4733 } 4734 4735 ParallelTaskTerminator* terminator() { return &_terminator; } 4736 4737 virtual void set_for_termination(int active_workers) { 4738 // This task calls set_n_termination() in par_non_clean_card_iterate_work() 4739 // in the young space (_par_seq_tasks) in the G1 heap 4740 // for SequentialSubTasksDone. 4741 // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap 4742 // both of which need setting by set_n_termination(). 4743 _g1h->SharedHeap::set_n_termination(active_workers); 4744 _g1h->set_n_termination(active_workers); 4745 terminator()->reset_for_reuse(active_workers); 4746 _n_workers = active_workers; 4747 } 4748 4749 void work(uint worker_id) { 4750 if (worker_id >= _n_workers) return; // no work needed this round 4751 4752 double start_time_ms = os::elapsedTime() * 1000.0; 4753 _g1h->g1_policy()->phase_times()->record_gc_worker_start_time(worker_id, start_time_ms); 4754 4755 { 4756 ResourceMark rm; 4757 HandleMark hm; 4758 4759 ReferenceProcessor* rp = _g1h->ref_processor_stw(); 4760 4761 G1ParScanThreadState pss(_g1h, worker_id, rp); 4762 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp); 4763 4764 pss.set_evac_failure_closure(&evac_failure_cl); 4765 4766 G1ParScanExtRootClosure only_scan_root_cl(_g1h, &pss, rp); 4767 G1ParScanMetadataClosure only_scan_metadata_cl(_g1h, &pss, rp); 4768 4769 G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss, rp); 4770 G1ParScanAndMarkMetadataClosure scan_mark_metadata_cl(_g1h, &pss, rp); 4771 4772 bool only_young = _g1h->g1_policy()->gcs_are_young(); 4773 G1KlassScanClosure scan_mark_klasses_cl_s(&scan_mark_metadata_cl, false); 4774 G1KlassScanClosure only_scan_klasses_cl_s(&only_scan_metadata_cl, only_young); 4775 4776 OopClosure* scan_root_cl = &only_scan_root_cl; 4777 G1KlassScanClosure* scan_klasses_cl = &only_scan_klasses_cl_s; 4778 4779 if (_g1h->g1_policy()->during_initial_mark_pause()) { 4780 // We also need to mark copied objects. 4781 scan_root_cl = &scan_mark_root_cl; 4782 scan_klasses_cl = &scan_mark_klasses_cl_s; 4783 } 4784 4785 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss); 4786 4787 // Don't scan the scavengable methods in the code cache as part 4788 // of strong root scanning. The code roots that point into a 4789 // region in the collection set are scanned when we scan the 4790 // region's RSet. 4791 int so = SharedHeap::SO_AllClasses | SharedHeap::SO_Strings; 4792 4793 pss.start_strong_roots(); 4794 _g1h->g1_process_strong_roots(/* is scavenging */ true, 4795 SharedHeap::ScanningOption(so), 4796 scan_root_cl, 4797 &push_heap_rs_cl, 4798 scan_klasses_cl, 4799 worker_id); 4800 pss.end_strong_roots(); 4801 4802 { 4803 double start = os::elapsedTime(); 4804 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator); 4805 evac.do_void(); 4806 double elapsed_ms = (os::elapsedTime()-start)*1000.0; 4807 double term_ms = pss.term_time()*1000.0; 4808 _g1h->g1_policy()->phase_times()->add_obj_copy_time(worker_id, elapsed_ms-term_ms); 4809 _g1h->g1_policy()->phase_times()->record_termination(worker_id, term_ms, pss.term_attempts()); 4810 } 4811 _g1h->g1_policy()->record_thread_age_table(pss.age_table()); 4812 _g1h->update_surviving_young_words(pss.surviving_young_words()+1); 4813 4814 if (ParallelGCVerbose) { 4815 MutexLocker x(stats_lock()); 4816 pss.print_termination_stats(worker_id); 4817 } 4818 4819 assert(pss.queue_is_empty(), "should be empty"); 4820 4821 // Close the inner scope so that the ResourceMark and HandleMark 4822 // destructors are executed here and are included as part of the 4823 // "GC Worker Time". 4824 } 4825 4826 double end_time_ms = os::elapsedTime() * 1000.0; 4827 _g1h->g1_policy()->phase_times()->record_gc_worker_end_time(worker_id, end_time_ms); 4828 } 4829 }; 4830 4831 // *** Common G1 Evacuation Stuff 4832 4833 // This method is run in a GC worker. 4834 4835 void 4836 G1CollectedHeap:: 4837 g1_process_strong_roots(bool is_scavenging, 4838 ScanningOption so, 4839 OopClosure* scan_non_heap_roots, 4840 OopsInHeapRegionClosure* scan_rs, 4841 G1KlassScanClosure* scan_klasses, 4842 uint worker_i) { 4843 4844 // First scan the strong roots 4845 double ext_roots_start = os::elapsedTime(); 4846 double closure_app_time_sec = 0.0; 4847 4848 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots); 4849 4850 process_strong_roots(false, // no scoping; this is parallel code 4851 so, 4852 &buf_scan_non_heap_roots, 4853 scan_klasses 4854 ); 4855 4856 // Now the CM ref_processor roots. 4857 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) { 4858 // We need to treat the discovered reference lists of the 4859 // concurrent mark ref processor as roots and keep entries 4860 // (which are added by the marking threads) on them live 4861 // until they can be processed at the end of marking. 4862 ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots); 4863 } 4864 4865 // Finish up any enqueued closure apps (attributed as object copy time). 4866 buf_scan_non_heap_roots.done(); 4867 4868 double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds(); 4869 4870 g1_policy()->phase_times()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0); 4871 4872 double ext_root_time_ms = 4873 ((os::elapsedTime() - ext_roots_start) - obj_copy_time_sec) * 1000.0; 4874 4875 g1_policy()->phase_times()->record_ext_root_scan_time(worker_i, ext_root_time_ms); 4876 4877 // During conc marking we have to filter the per-thread SATB buffers 4878 // to make sure we remove any oops into the CSet (which will show up 4879 // as implicitly live). 4880 double satb_filtering_ms = 0.0; 4881 if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers)) { 4882 if (mark_in_progress()) { 4883 double satb_filter_start = os::elapsedTime(); 4884 4885 JavaThread::satb_mark_queue_set().filter_thread_buffers(); 4886 4887 satb_filtering_ms = (os::elapsedTime() - satb_filter_start) * 1000.0; 4888 } 4889 } 4890 g1_policy()->phase_times()->record_satb_filtering_time(worker_i, satb_filtering_ms); 4891 4892 // If this is an initial mark pause, and we're not scanning 4893 // the entire code cache, we need to mark the oops in the 4894 // strong code root lists for the regions that are not in 4895 // the collection set. 4896 // Note all threads participate in this set of root tasks. 4897 double mark_strong_code_roots_ms = 0.0; 4898 if (g1_policy()->during_initial_mark_pause() && !(so & SO_AllCodeCache)) { 4899 double mark_strong_roots_start = os::elapsedTime(); 4900 mark_strong_code_roots(worker_i); 4901 mark_strong_code_roots_ms = (os::elapsedTime() - mark_strong_roots_start) * 1000.0; 4902 } 4903 g1_policy()->phase_times()->record_strong_code_root_mark_time(worker_i, mark_strong_code_roots_ms); 4904 4905 // Now scan the complement of the collection set. 4906 CodeBlobToOopClosure eager_scan_code_roots(scan_non_heap_roots, true /* do_marking */); 4907 g1_rem_set()->oops_into_collection_set_do(scan_rs, &eager_scan_code_roots, worker_i); 4908 4909 _process_strong_tasks->all_tasks_completed(); 4910 } 4911 4912 class G1StringSymbolTableUnlinkTask : public AbstractGangTask { 4913 private: 4914 BoolObjectClosure* _is_alive; 4915 int _initial_string_table_size; 4916 int _initial_symbol_table_size; 4917 4918 bool _process_strings; 4919 int _strings_processed; 4920 int _strings_removed; 4921 4922 bool _process_symbols; 4923 int _symbols_processed; 4924 int _symbols_removed; 4925 4926 bool _do_in_parallel; 4927 public: 4928 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) : 4929 AbstractGangTask("Par String/Symbol table unlink"), _is_alive(is_alive), 4930 _do_in_parallel(G1CollectedHeap::use_parallel_gc_threads()), 4931 _process_strings(process_strings), _strings_processed(0), _strings_removed(0), 4932 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) { 4933 4934 _initial_string_table_size = StringTable::the_table()->table_size(); 4935 _initial_symbol_table_size = SymbolTable::the_table()->table_size(); 4936 if (process_strings) { 4937 StringTable::clear_parallel_claimed_index(); 4938 } 4939 if (process_symbols) { 4940 SymbolTable::clear_parallel_claimed_index(); 4941 } 4942 } 4943 4944 ~G1StringSymbolTableUnlinkTask() { 4945 guarantee(!_process_strings || !_do_in_parallel || StringTable::parallel_claimed_index() >= _initial_string_table_size, 4946 err_msg("claim value %d after unlink less than initial string table size %d", 4947 StringTable::parallel_claimed_index(), _initial_string_table_size)); 4948 guarantee(!_process_symbols || !_do_in_parallel || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size, 4949 err_msg("claim value %d after unlink less than initial symbol table size %d", 4950 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size)); 4951 } 4952 4953 void work(uint worker_id) { 4954 if (_do_in_parallel) { 4955 int strings_processed = 0; 4956 int strings_removed = 0; 4957 int symbols_processed = 0; 4958 int symbols_removed = 0; 4959 if (_process_strings) { 4960 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed); 4961 Atomic::add(strings_processed, &_strings_processed); 4962 Atomic::add(strings_removed, &_strings_removed); 4963 } 4964 if (_process_symbols) { 4965 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed); 4966 Atomic::add(symbols_processed, &_symbols_processed); 4967 Atomic::add(symbols_removed, &_symbols_removed); 4968 } 4969 } else { 4970 if (_process_strings) { 4971 StringTable::unlink(_is_alive, &_strings_processed, &_strings_removed); 4972 } 4973 if (_process_symbols) { 4974 SymbolTable::unlink(&_symbols_processed, &_symbols_removed); 4975 } 4976 } 4977 } 4978 4979 size_t strings_processed() const { return (size_t)_strings_processed; } 4980 size_t strings_removed() const { return (size_t)_strings_removed; } 4981 4982 size_t symbols_processed() const { return (size_t)_symbols_processed; } 4983 size_t symbols_removed() const { return (size_t)_symbols_removed; } 4984 }; 4985 4986 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive, 4987 bool process_strings, bool process_symbols) { 4988 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ? 4989 _g1h->workers()->active_workers() : 1); 4990 4991 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols); 4992 if (G1CollectedHeap::use_parallel_gc_threads()) { 4993 set_par_threads(n_workers); 4994 workers()->run_task(&g1_unlink_task); 4995 set_par_threads(0); 4996 } else { 4997 g1_unlink_task.work(0); 4998 } 4999 if (G1TraceStringSymbolTableScrubbing) { 5000 gclog_or_tty->print_cr("Cleaned string and symbol table, " 5001 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, " 5002 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed", 5003 g1_unlink_task.strings_processed(), g1_unlink_task.strings_removed(), 5004 g1_unlink_task.symbols_processed(), g1_unlink_task.symbols_removed()); 5005 } 5006 5007 if (G1StringDedup::is_enabled()) { 5008 G1StringDedup::unlink(is_alive); 5009 } 5010 } 5011 5012 class G1RedirtyLoggedCardsTask : public AbstractGangTask { 5013 private: 5014 DirtyCardQueueSet* _queue; 5015 public: 5016 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { } 5017 5018 virtual void work(uint worker_id) { 5019 double start_time = os::elapsedTime(); 5020 5021 RedirtyLoggedCardTableEntryClosure cl; 5022 if (G1CollectedHeap::heap()->use_parallel_gc_threads()) { 5023 _queue->par_apply_closure_to_all_completed_buffers(&cl); 5024 } else { 5025 _queue->apply_closure_to_all_completed_buffers(&cl); 5026 } 5027 5028 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times(); 5029 timer->record_redirty_logged_cards_time_ms(worker_id, (os::elapsedTime() - start_time) * 1000.0); 5030 timer->record_redirty_logged_cards_processed_cards(worker_id, cl.num_processed()); 5031 } 5032 }; 5033 5034 void G1CollectedHeap::redirty_logged_cards() { 5035 guarantee(G1DeferredRSUpdate, "Must only be called when using deferred RS updates."); 5036 double redirty_logged_cards_start = os::elapsedTime(); 5037 5038 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ? 5039 _g1h->workers()->active_workers() : 1); 5040 5041 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set()); 5042 dirty_card_queue_set().reset_for_par_iteration(); 5043 if (use_parallel_gc_threads()) { 5044 set_par_threads(n_workers); 5045 workers()->run_task(&redirty_task); 5046 set_par_threads(0); 5047 } else { 5048 redirty_task.work(0); 5049 } 5050 5051 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set(); 5052 dcq.merge_bufferlists(&dirty_card_queue_set()); 5053 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed"); 5054 5055 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0); 5056 } 5057 5058 // Weak Reference Processing support 5059 5060 // An always "is_alive" closure that is used to preserve referents. 5061 // If the object is non-null then it's alive. Used in the preservation 5062 // of referent objects that are pointed to by reference objects 5063 // discovered by the CM ref processor. 5064 class G1AlwaysAliveClosure: public BoolObjectClosure { 5065 G1CollectedHeap* _g1; 5066 public: 5067 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 5068 bool do_object_b(oop p) { 5069 if (p != NULL) { 5070 return true; 5071 } 5072 return false; 5073 } 5074 }; 5075 5076 bool G1STWIsAliveClosure::do_object_b(oop p) { 5077 // An object is reachable if it is outside the collection set, 5078 // or is inside and copied. 5079 return !_g1->obj_in_cs(p) || p->is_forwarded(); 5080 } 5081 5082 // Non Copying Keep Alive closure 5083 class G1KeepAliveClosure: public OopClosure { 5084 G1CollectedHeap* _g1; 5085 public: 5086 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 5087 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } 5088 void do_oop( oop* p) { 5089 oop obj = *p; 5090 5091 if (_g1->obj_in_cs(obj)) { 5092 assert( obj->is_forwarded(), "invariant" ); 5093 *p = obj->forwardee(); 5094 } 5095 } 5096 }; 5097 5098 // Copying Keep Alive closure - can be called from both 5099 // serial and parallel code as long as different worker 5100 // threads utilize different G1ParScanThreadState instances 5101 // and different queues. 5102 5103 class G1CopyingKeepAliveClosure: public OopClosure { 5104 G1CollectedHeap* _g1h; 5105 OopClosure* _copy_non_heap_obj_cl; 5106 G1ParScanThreadState* _par_scan_state; 5107 5108 public: 5109 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, 5110 OopClosure* non_heap_obj_cl, 5111 G1ParScanThreadState* pss): 5112 _g1h(g1h), 5113 _copy_non_heap_obj_cl(non_heap_obj_cl), 5114 _par_scan_state(pss) 5115 {} 5116 5117 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 5118 virtual void do_oop( oop* p) { do_oop_work(p); } 5119 5120 template <class T> void do_oop_work(T* p) { 5121 oop obj = oopDesc::load_decode_heap_oop(p); 5122 5123 if (_g1h->obj_in_cs(obj)) { 5124 // If the referent object has been forwarded (either copied 5125 // to a new location or to itself in the event of an 5126 // evacuation failure) then we need to update the reference 5127 // field and, if both reference and referent are in the G1 5128 // heap, update the RSet for the referent. 5129 // 5130 // If the referent has not been forwarded then we have to keep 5131 // it alive by policy. Therefore we have copy the referent. 5132 // 5133 // If the reference field is in the G1 heap then we can push 5134 // on the PSS queue. When the queue is drained (after each 5135 // phase of reference processing) the object and it's followers 5136 // will be copied, the reference field set to point to the 5137 // new location, and the RSet updated. Otherwise we need to 5138 // use the the non-heap or metadata closures directly to copy 5139 // the referent object and update the pointer, while avoiding 5140 // updating the RSet. 5141 5142 if (_g1h->is_in_g1_reserved(p)) { 5143 _par_scan_state->push_on_queue(p); 5144 } else { 5145 assert(!Metaspace::contains((const void*)p), 5146 err_msg("Unexpectedly found a pointer from metadata: " 5147 PTR_FORMAT, p)); 5148 _copy_non_heap_obj_cl->do_oop(p); 5149 } 5150 } 5151 } 5152 }; 5153 5154 // Serial drain queue closure. Called as the 'complete_gc' 5155 // closure for each discovered list in some of the 5156 // reference processing phases. 5157 5158 class G1STWDrainQueueClosure: public VoidClosure { 5159 protected: 5160 G1CollectedHeap* _g1h; 5161 G1ParScanThreadState* _par_scan_state; 5162 5163 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 5164 5165 public: 5166 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : 5167 _g1h(g1h), 5168 _par_scan_state(pss) 5169 { } 5170 5171 void do_void() { 5172 G1ParScanThreadState* const pss = par_scan_state(); 5173 pss->trim_queue(); 5174 } 5175 }; 5176 5177 // Parallel Reference Processing closures 5178 5179 // Implementation of AbstractRefProcTaskExecutor for parallel reference 5180 // processing during G1 evacuation pauses. 5181 5182 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 5183 private: 5184 G1CollectedHeap* _g1h; 5185 RefToScanQueueSet* _queues; 5186 FlexibleWorkGang* _workers; 5187 int _active_workers; 5188 5189 public: 5190 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, 5191 FlexibleWorkGang* workers, 5192 RefToScanQueueSet *task_queues, 5193 int n_workers) : 5194 _g1h(g1h), 5195 _queues(task_queues), 5196 _workers(workers), 5197 _active_workers(n_workers) 5198 { 5199 assert(n_workers > 0, "shouldn't call this otherwise"); 5200 } 5201 5202 // Executes the given task using concurrent marking worker threads. 5203 virtual void execute(ProcessTask& task); 5204 virtual void execute(EnqueueTask& task); 5205 }; 5206 5207 // Gang task for possibly parallel reference processing 5208 5209 class G1STWRefProcTaskProxy: public AbstractGangTask { 5210 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 5211 ProcessTask& _proc_task; 5212 G1CollectedHeap* _g1h; 5213 RefToScanQueueSet *_task_queues; 5214 ParallelTaskTerminator* _terminator; 5215 5216 public: 5217 G1STWRefProcTaskProxy(ProcessTask& proc_task, 5218 G1CollectedHeap* g1h, 5219 RefToScanQueueSet *task_queues, 5220 ParallelTaskTerminator* terminator) : 5221 AbstractGangTask("Process reference objects in parallel"), 5222 _proc_task(proc_task), 5223 _g1h(g1h), 5224 _task_queues(task_queues), 5225 _terminator(terminator) 5226 {} 5227 5228 virtual void work(uint worker_id) { 5229 // The reference processing task executed by a single worker. 5230 ResourceMark rm; 5231 HandleMark hm; 5232 5233 G1STWIsAliveClosure is_alive(_g1h); 5234 5235 G1ParScanThreadState pss(_g1h, worker_id, NULL); 5236 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL); 5237 5238 pss.set_evac_failure_closure(&evac_failure_cl); 5239 5240 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL); 5241 5242 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL); 5243 5244 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5245 5246 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5247 // We also need to mark copied objects. 5248 copy_non_heap_cl = ©_mark_non_heap_cl; 5249 } 5250 5251 // Keep alive closure. 5252 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss); 5253 5254 // Complete GC closure 5255 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator); 5256 5257 // Call the reference processing task's work routine. 5258 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); 5259 5260 // Note we cannot assert that the refs array is empty here as not all 5261 // of the processing tasks (specifically phase2 - pp2_work) execute 5262 // the complete_gc closure (which ordinarily would drain the queue) so 5263 // the queue may not be empty. 5264 } 5265 }; 5266 5267 // Driver routine for parallel reference processing. 5268 // Creates an instance of the ref processing gang 5269 // task and has the worker threads execute it. 5270 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) { 5271 assert(_workers != NULL, "Need parallel worker threads."); 5272 5273 ParallelTaskTerminator terminator(_active_workers, _queues); 5274 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator); 5275 5276 _g1h->set_par_threads(_active_workers); 5277 _workers->run_task(&proc_task_proxy); 5278 _g1h->set_par_threads(0); 5279 } 5280 5281 // Gang task for parallel reference enqueueing. 5282 5283 class G1STWRefEnqueueTaskProxy: public AbstractGangTask { 5284 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; 5285 EnqueueTask& _enq_task; 5286 5287 public: 5288 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) : 5289 AbstractGangTask("Enqueue reference objects in parallel"), 5290 _enq_task(enq_task) 5291 { } 5292 5293 virtual void work(uint worker_id) { 5294 _enq_task.work(worker_id); 5295 } 5296 }; 5297 5298 // Driver routine for parallel reference enqueueing. 5299 // Creates an instance of the ref enqueueing gang 5300 // task and has the worker threads execute it. 5301 5302 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) { 5303 assert(_workers != NULL, "Need parallel worker threads."); 5304 5305 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task); 5306 5307 _g1h->set_par_threads(_active_workers); 5308 _workers->run_task(&enq_task_proxy); 5309 _g1h->set_par_threads(0); 5310 } 5311 5312 // End of weak reference support closures 5313 5314 // Abstract task used to preserve (i.e. copy) any referent objects 5315 // that are in the collection set and are pointed to by reference 5316 // objects discovered by the CM ref processor. 5317 5318 class G1ParPreserveCMReferentsTask: public AbstractGangTask { 5319 protected: 5320 G1CollectedHeap* _g1h; 5321 RefToScanQueueSet *_queues; 5322 ParallelTaskTerminator _terminator; 5323 uint _n_workers; 5324 5325 public: 5326 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) : 5327 AbstractGangTask("ParPreserveCMReferents"), 5328 _g1h(g1h), 5329 _queues(task_queues), 5330 _terminator(workers, _queues), 5331 _n_workers(workers) 5332 { } 5333 5334 void work(uint worker_id) { 5335 ResourceMark rm; 5336 HandleMark hm; 5337 5338 G1ParScanThreadState pss(_g1h, worker_id, NULL); 5339 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL); 5340 5341 pss.set_evac_failure_closure(&evac_failure_cl); 5342 5343 assert(pss.queue_is_empty(), "both queue and overflow should be empty"); 5344 5345 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL); 5346 5347 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL); 5348 5349 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5350 5351 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5352 // We also need to mark copied objects. 5353 copy_non_heap_cl = ©_mark_non_heap_cl; 5354 } 5355 5356 // Is alive closure 5357 G1AlwaysAliveClosure always_alive(_g1h); 5358 5359 // Copying keep alive closure. Applied to referent objects that need 5360 // to be copied. 5361 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss); 5362 5363 ReferenceProcessor* rp = _g1h->ref_processor_cm(); 5364 5365 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q(); 5366 uint stride = MIN2(MAX2(_n_workers, 1U), limit); 5367 5368 // limit is set using max_num_q() - which was set using ParallelGCThreads. 5369 // So this must be true - but assert just in case someone decides to 5370 // change the worker ids. 5371 assert(0 <= worker_id && worker_id < limit, "sanity"); 5372 assert(!rp->discovery_is_atomic(), "check this code"); 5373 5374 // Select discovered lists [i, i+stride, i+2*stride,...,limit) 5375 for (uint idx = worker_id; idx < limit; idx += stride) { 5376 DiscoveredList& ref_list = rp->discovered_refs()[idx]; 5377 5378 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive); 5379 while (iter.has_next()) { 5380 // Since discovery is not atomic for the CM ref processor, we 5381 // can see some null referent objects. 5382 iter.load_ptrs(DEBUG_ONLY(true)); 5383 oop ref = iter.obj(); 5384 5385 // This will filter nulls. 5386 if (iter.is_referent_alive()) { 5387 iter.make_referent_alive(); 5388 } 5389 iter.move_to_next(); 5390 } 5391 } 5392 5393 // Drain the queue - which may cause stealing 5394 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator); 5395 drain_queue.do_void(); 5396 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure 5397 assert(pss.queue_is_empty(), "should be"); 5398 } 5399 }; 5400 5401 // Weak Reference processing during an evacuation pause (part 1). 5402 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) { 5403 double ref_proc_start = os::elapsedTime(); 5404 5405 ReferenceProcessor* rp = _ref_processor_stw; 5406 assert(rp->discovery_enabled(), "should have been enabled"); 5407 5408 // Any reference objects, in the collection set, that were 'discovered' 5409 // by the CM ref processor should have already been copied (either by 5410 // applying the external root copy closure to the discovered lists, or 5411 // by following an RSet entry). 5412 // 5413 // But some of the referents, that are in the collection set, that these 5414 // reference objects point to may not have been copied: the STW ref 5415 // processor would have seen that the reference object had already 5416 // been 'discovered' and would have skipped discovering the reference, 5417 // but would not have treated the reference object as a regular oop. 5418 // As a result the copy closure would not have been applied to the 5419 // referent object. 5420 // 5421 // We need to explicitly copy these referent objects - the references 5422 // will be processed at the end of remarking. 5423 // 5424 // We also need to do this copying before we process the reference 5425 // objects discovered by the STW ref processor in case one of these 5426 // referents points to another object which is also referenced by an 5427 // object discovered by the STW ref processor. 5428 5429 assert(!G1CollectedHeap::use_parallel_gc_threads() || 5430 no_of_gc_workers == workers()->active_workers(), 5431 "Need to reset active GC workers"); 5432 5433 set_par_threads(no_of_gc_workers); 5434 G1ParPreserveCMReferentsTask keep_cm_referents(this, 5435 no_of_gc_workers, 5436 _task_queues); 5437 5438 if (G1CollectedHeap::use_parallel_gc_threads()) { 5439 workers()->run_task(&keep_cm_referents); 5440 } else { 5441 keep_cm_referents.work(0); 5442 } 5443 5444 set_par_threads(0); 5445 5446 // Closure to test whether a referent is alive. 5447 G1STWIsAliveClosure is_alive(this); 5448 5449 // Even when parallel reference processing is enabled, the processing 5450 // of JNI refs is serial and performed serially by the current thread 5451 // rather than by a worker. The following PSS will be used for processing 5452 // JNI refs. 5453 5454 // Use only a single queue for this PSS. 5455 G1ParScanThreadState pss(this, 0, NULL); 5456 5457 // We do not embed a reference processor in the copying/scanning 5458 // closures while we're actually processing the discovered 5459 // reference objects. 5460 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL); 5461 5462 pss.set_evac_failure_closure(&evac_failure_cl); 5463 5464 assert(pss.queue_is_empty(), "pre-condition"); 5465 5466 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL); 5467 5468 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL); 5469 5470 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5471 5472 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5473 // We also need to mark copied objects. 5474 copy_non_heap_cl = ©_mark_non_heap_cl; 5475 } 5476 5477 // Keep alive closure. 5478 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, &pss); 5479 5480 // Serial Complete GC closure 5481 G1STWDrainQueueClosure drain_queue(this, &pss); 5482 5483 // Setup the soft refs policy... 5484 rp->setup_policy(false); 5485 5486 ReferenceProcessorStats stats; 5487 if (!rp->processing_is_mt()) { 5488 // Serial reference processing... 5489 stats = rp->process_discovered_references(&is_alive, 5490 &keep_alive, 5491 &drain_queue, 5492 NULL, 5493 _gc_timer_stw, 5494 _gc_tracer_stw->gc_id()); 5495 } else { 5496 // Parallel reference processing 5497 assert(rp->num_q() == no_of_gc_workers, "sanity"); 5498 assert(no_of_gc_workers <= rp->max_num_q(), "sanity"); 5499 5500 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers); 5501 stats = rp->process_discovered_references(&is_alive, 5502 &keep_alive, 5503 &drain_queue, 5504 &par_task_executor, 5505 _gc_timer_stw, 5506 _gc_tracer_stw->gc_id()); 5507 } 5508 5509 _gc_tracer_stw->report_gc_reference_stats(stats); 5510 5511 // We have completed copying any necessary live referent objects. 5512 assert(pss.queue_is_empty(), "both queue and overflow should be empty"); 5513 5514 double ref_proc_time = os::elapsedTime() - ref_proc_start; 5515 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 5516 } 5517 5518 // Weak Reference processing during an evacuation pause (part 2). 5519 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) { 5520 double ref_enq_start = os::elapsedTime(); 5521 5522 ReferenceProcessor* rp = _ref_processor_stw; 5523 assert(!rp->discovery_enabled(), "should have been disabled as part of processing"); 5524 5525 // Now enqueue any remaining on the discovered lists on to 5526 // the pending list. 5527 if (!rp->processing_is_mt()) { 5528 // Serial reference processing... 5529 rp->enqueue_discovered_references(); 5530 } else { 5531 // Parallel reference enqueueing 5532 5533 assert(no_of_gc_workers == workers()->active_workers(), 5534 "Need to reset active workers"); 5535 assert(rp->num_q() == no_of_gc_workers, "sanity"); 5536 assert(no_of_gc_workers <= rp->max_num_q(), "sanity"); 5537 5538 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers); 5539 rp->enqueue_discovered_references(&par_task_executor); 5540 } 5541 5542 rp->verify_no_references_recorded(); 5543 assert(!rp->discovery_enabled(), "should have been disabled"); 5544 5545 // FIXME 5546 // CM's reference processing also cleans up the string and symbol tables. 5547 // Should we do that here also? We could, but it is a serial operation 5548 // and could significantly increase the pause time. 5549 5550 double ref_enq_time = os::elapsedTime() - ref_enq_start; 5551 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0); 5552 } 5553 5554 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) { 5555 _expand_heap_after_alloc_failure = true; 5556 _evacuation_failed = false; 5557 5558 // Should G1EvacuationFailureALot be in effect for this GC? 5559 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) 5560 5561 g1_rem_set()->prepare_for_oops_into_collection_set_do(); 5562 5563 // Disable the hot card cache. 5564 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 5565 hot_card_cache->reset_hot_cache_claimed_index(); 5566 hot_card_cache->set_use_cache(false); 5567 5568 uint n_workers; 5569 if (G1CollectedHeap::use_parallel_gc_threads()) { 5570 n_workers = 5571 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 5572 workers()->active_workers(), 5573 Threads::number_of_non_daemon_threads()); 5574 assert(UseDynamicNumberOfGCThreads || 5575 n_workers == workers()->total_workers(), 5576 "If not dynamic should be using all the workers"); 5577 workers()->set_active_workers(n_workers); 5578 set_par_threads(n_workers); 5579 } else { 5580 assert(n_par_threads() == 0, 5581 "Should be the original non-parallel value"); 5582 n_workers = 1; 5583 } 5584 5585 G1ParTask g1_par_task(this, _task_queues); 5586 5587 init_for_evac_failure(NULL); 5588 5589 rem_set()->prepare_for_younger_refs_iterate(true); 5590 5591 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty"); 5592 double start_par_time_sec = os::elapsedTime(); 5593 double end_par_time_sec; 5594 5595 { 5596 StrongRootsScope srs(this); 5597 5598 if (G1CollectedHeap::use_parallel_gc_threads()) { 5599 // The individual threads will set their evac-failure closures. 5600 if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr(); 5601 // These tasks use ShareHeap::_process_strong_tasks 5602 assert(UseDynamicNumberOfGCThreads || 5603 workers()->active_workers() == workers()->total_workers(), 5604 "If not dynamic should be using all the workers"); 5605 workers()->run_task(&g1_par_task); 5606 } else { 5607 g1_par_task.set_for_termination(n_workers); 5608 g1_par_task.work(0); 5609 } 5610 end_par_time_sec = os::elapsedTime(); 5611 5612 // Closing the inner scope will execute the destructor 5613 // for the StrongRootsScope object. We record the current 5614 // elapsed time before closing the scope so that time 5615 // taken for the SRS destructor is NOT included in the 5616 // reported parallel time. 5617 } 5618 5619 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0; 5620 g1_policy()->phase_times()->record_par_time(par_time_ms); 5621 5622 double code_root_fixup_time_ms = 5623 (os::elapsedTime() - end_par_time_sec) * 1000.0; 5624 g1_policy()->phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms); 5625 5626 set_par_threads(0); 5627 5628 // Process any discovered reference objects - we have 5629 // to do this _before_ we retire the GC alloc regions 5630 // as we may have to copy some 'reachable' referent 5631 // objects (and their reachable sub-graphs) that were 5632 // not copied during the pause. 5633 process_discovered_references(n_workers); 5634 5635 // Weak root processing. 5636 { 5637 G1STWIsAliveClosure is_alive(this); 5638 G1KeepAliveClosure keep_alive(this); 5639 JNIHandles::weak_oops_do(&is_alive, &keep_alive); 5640 if (G1StringDedup::is_enabled()) { 5641 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive); 5642 } 5643 } 5644 5645 release_gc_alloc_regions(n_workers, evacuation_info); 5646 g1_rem_set()->cleanup_after_oops_into_collection_set_do(); 5647 5648 // Reset and re-enable the hot card cache. 5649 // Note the counts for the cards in the regions in the 5650 // collection set are reset when the collection set is freed. 5651 hot_card_cache->reset_hot_cache(); 5652 hot_card_cache->set_use_cache(true); 5653 5654 // Migrate the strong code roots attached to each region in 5655 // the collection set. Ideally we would like to do this 5656 // after we have finished the scanning/evacuation of the 5657 // strong code roots for a particular heap region. 5658 migrate_strong_code_roots(); 5659 5660 purge_code_root_memory(); 5661 5662 if (g1_policy()->during_initial_mark_pause()) { 5663 // Reset the claim values set during marking the strong code roots 5664 reset_heap_region_claim_values(); 5665 } 5666 5667 finalize_for_evac_failure(); 5668 5669 if (evacuation_failed()) { 5670 remove_self_forwarding_pointers(); 5671 5672 // Reset the G1EvacuationFailureALot counters and flags 5673 // Note: the values are reset only when an actual 5674 // evacuation failure occurs. 5675 NOT_PRODUCT(reset_evacuation_should_fail();) 5676 } 5677 5678 // Enqueue any remaining references remaining on the STW 5679 // reference processor's discovered lists. We need to do 5680 // this after the card table is cleaned (and verified) as 5681 // the act of enqueueing entries on to the pending list 5682 // will log these updates (and dirty their associated 5683 // cards). We need these updates logged to update any 5684 // RSets. 5685 enqueue_discovered_references(n_workers); 5686 5687 if (G1DeferredRSUpdate) { 5688 redirty_logged_cards(); 5689 } 5690 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 5691 } 5692 5693 void G1CollectedHeap::free_region(HeapRegion* hr, 5694 FreeRegionList* free_list, 5695 bool par, 5696 bool locked) { 5697 assert(!hr->isHumongous(), "this is only for non-humongous regions"); 5698 assert(!hr->is_empty(), "the region should not be empty"); 5699 assert(free_list != NULL, "pre-condition"); 5700 5701 if (G1VerifyBitmaps) { 5702 MemRegion mr(hr->bottom(), hr->end()); 5703 concurrent_mark()->clearRangePrevBitmap(mr); 5704 } 5705 5706 // Clear the card counts for this region. 5707 // Note: we only need to do this if the region is not young 5708 // (since we don't refine cards in young regions). 5709 if (!hr->is_young()) { 5710 _cg1r->hot_card_cache()->reset_card_counts(hr); 5711 } 5712 hr->hr_clear(par, true /* clear_space */, locked /* locked */); 5713 free_list->add_ordered(hr); 5714 } 5715 5716 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 5717 FreeRegionList* free_list, 5718 bool par) { 5719 assert(hr->startsHumongous(), "this is only for starts humongous regions"); 5720 assert(free_list != NULL, "pre-condition"); 5721 5722 size_t hr_capacity = hr->capacity(); 5723 // We need to read this before we make the region non-humongous, 5724 // otherwise the information will be gone. 5725 uint last_index = hr->last_hc_index(); 5726 hr->set_notHumongous(); 5727 free_region(hr, free_list, par); 5728 5729 uint i = hr->hrs_index() + 1; 5730 while (i < last_index) { 5731 HeapRegion* curr_hr = region_at(i); 5732 assert(curr_hr->continuesHumongous(), "invariant"); 5733 curr_hr->set_notHumongous(); 5734 free_region(curr_hr, free_list, par); 5735 i += 1; 5736 } 5737 } 5738 5739 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed, 5740 const HeapRegionSetCount& humongous_regions_removed) { 5741 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) { 5742 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 5743 _old_set.bulk_remove(old_regions_removed); 5744 _humongous_set.bulk_remove(humongous_regions_removed); 5745 } 5746 5747 } 5748 5749 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) { 5750 assert(list != NULL, "list can't be null"); 5751 if (!list->is_empty()) { 5752 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag); 5753 _free_list.add_ordered(list); 5754 } 5755 } 5756 5757 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) { 5758 assert(_summary_bytes_used >= bytes, 5759 err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" should be >= bytes: "SIZE_FORMAT, 5760 _summary_bytes_used, bytes)); 5761 _summary_bytes_used -= bytes; 5762 } 5763 5764 class G1ParCleanupCTTask : public AbstractGangTask { 5765 G1SATBCardTableModRefBS* _ct_bs; 5766 G1CollectedHeap* _g1h; 5767 HeapRegion* volatile _su_head; 5768 public: 5769 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs, 5770 G1CollectedHeap* g1h) : 5771 AbstractGangTask("G1 Par Cleanup CT Task"), 5772 _ct_bs(ct_bs), _g1h(g1h) { } 5773 5774 void work(uint worker_id) { 5775 HeapRegion* r; 5776 while (r = _g1h->pop_dirty_cards_region()) { 5777 clear_cards(r); 5778 } 5779 } 5780 5781 void clear_cards(HeapRegion* r) { 5782 // Cards of the survivors should have already been dirtied. 5783 if (!r->is_survivor()) { 5784 _ct_bs->clear(MemRegion(r->bottom(), r->end())); 5785 } 5786 } 5787 }; 5788 5789 #ifndef PRODUCT 5790 class G1VerifyCardTableCleanup: public HeapRegionClosure { 5791 G1CollectedHeap* _g1h; 5792 G1SATBCardTableModRefBS* _ct_bs; 5793 public: 5794 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs) 5795 : _g1h(g1h), _ct_bs(ct_bs) { } 5796 virtual bool doHeapRegion(HeapRegion* r) { 5797 if (r->is_survivor()) { 5798 _g1h->verify_dirty_region(r); 5799 } else { 5800 _g1h->verify_not_dirty_region(r); 5801 } 5802 return false; 5803 } 5804 }; 5805 5806 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) { 5807 // All of the region should be clean. 5808 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5809 MemRegion mr(hr->bottom(), hr->end()); 5810 ct_bs->verify_not_dirty_region(mr); 5811 } 5812 5813 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) { 5814 // We cannot guarantee that [bottom(),end()] is dirty. Threads 5815 // dirty allocated blocks as they allocate them. The thread that 5816 // retires each region and replaces it with a new one will do a 5817 // maximal allocation to fill in [pre_dummy_top(),end()] but will 5818 // not dirty that area (one less thing to have to do while holding 5819 // a lock). So we can only verify that [bottom(),pre_dummy_top()] 5820 // is dirty. 5821 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5822 MemRegion mr(hr->bottom(), hr->pre_dummy_top()); 5823 if (hr->is_young()) { 5824 ct_bs->verify_g1_young_region(mr); 5825 } else { 5826 ct_bs->verify_dirty_region(mr); 5827 } 5828 } 5829 5830 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) { 5831 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5832 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) { 5833 verify_dirty_region(hr); 5834 } 5835 } 5836 5837 void G1CollectedHeap::verify_dirty_young_regions() { 5838 verify_dirty_young_list(_young_list->first_region()); 5839 } 5840 5841 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap, 5842 HeapWord* tams, HeapWord* end) { 5843 guarantee(tams <= end, 5844 err_msg("tams: "PTR_FORMAT" end: "PTR_FORMAT, tams, end)); 5845 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end); 5846 if (result < end) { 5847 gclog_or_tty->cr(); 5848 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: "PTR_FORMAT, 5849 bitmap_name, result); 5850 gclog_or_tty->print_cr("## %s tams: "PTR_FORMAT" end: "PTR_FORMAT, 5851 bitmap_name, tams, end); 5852 return false; 5853 } 5854 return true; 5855 } 5856 5857 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) { 5858 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap(); 5859 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap(); 5860 5861 HeapWord* bottom = hr->bottom(); 5862 HeapWord* ptams = hr->prev_top_at_mark_start(); 5863 HeapWord* ntams = hr->next_top_at_mark_start(); 5864 HeapWord* end = hr->end(); 5865 5866 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end); 5867 5868 bool res_n = true; 5869 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window 5870 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap 5871 // if we happen to be in that state. 5872 if (mark_in_progress() || !_cmThread->in_progress()) { 5873 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end); 5874 } 5875 if (!res_p || !res_n) { 5876 gclog_or_tty->print_cr("#### Bitmap verification failed for "HR_FORMAT, 5877 HR_FORMAT_PARAMS(hr)); 5878 gclog_or_tty->print_cr("#### Caller: %s", caller); 5879 return false; 5880 } 5881 return true; 5882 } 5883 5884 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) { 5885 if (!G1VerifyBitmaps) return; 5886 5887 guarantee(verify_bitmaps(caller, hr), "bitmap verification"); 5888 } 5889 5890 class G1VerifyBitmapClosure : public HeapRegionClosure { 5891 private: 5892 const char* _caller; 5893 G1CollectedHeap* _g1h; 5894 bool _failures; 5895 5896 public: 5897 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) : 5898 _caller(caller), _g1h(g1h), _failures(false) { } 5899 5900 bool failures() { return _failures; } 5901 5902 virtual bool doHeapRegion(HeapRegion* hr) { 5903 if (hr->continuesHumongous()) return false; 5904 5905 bool result = _g1h->verify_bitmaps(_caller, hr); 5906 if (!result) { 5907 _failures = true; 5908 } 5909 return false; 5910 } 5911 }; 5912 5913 void G1CollectedHeap::check_bitmaps(const char* caller) { 5914 if (!G1VerifyBitmaps) return; 5915 5916 G1VerifyBitmapClosure cl(caller, this); 5917 heap_region_iterate(&cl); 5918 guarantee(!cl.failures(), "bitmap verification"); 5919 } 5920 #endif // PRODUCT 5921 5922 void G1CollectedHeap::cleanUpCardTable() { 5923 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5924 double start = os::elapsedTime(); 5925 5926 { 5927 // Iterate over the dirty cards region list. 5928 G1ParCleanupCTTask cleanup_task(ct_bs, this); 5929 5930 if (G1CollectedHeap::use_parallel_gc_threads()) { 5931 set_par_threads(); 5932 workers()->run_task(&cleanup_task); 5933 set_par_threads(0); 5934 } else { 5935 while (_dirty_cards_region_list) { 5936 HeapRegion* r = _dirty_cards_region_list; 5937 cleanup_task.clear_cards(r); 5938 _dirty_cards_region_list = r->get_next_dirty_cards_region(); 5939 if (_dirty_cards_region_list == r) { 5940 // The last region. 5941 _dirty_cards_region_list = NULL; 5942 } 5943 r->set_next_dirty_cards_region(NULL); 5944 } 5945 } 5946 #ifndef PRODUCT 5947 if (G1VerifyCTCleanup || VerifyAfterGC) { 5948 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs); 5949 heap_region_iterate(&cleanup_verifier); 5950 } 5951 #endif 5952 } 5953 5954 double elapsed = os::elapsedTime() - start; 5955 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0); 5956 } 5957 5958 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) { 5959 size_t pre_used = 0; 5960 FreeRegionList local_free_list("Local List for CSet Freeing"); 5961 5962 double young_time_ms = 0.0; 5963 double non_young_time_ms = 0.0; 5964 5965 // Since the collection set is a superset of the the young list, 5966 // all we need to do to clear the young list is clear its 5967 // head and length, and unlink any young regions in the code below 5968 _young_list->clear(); 5969 5970 G1CollectorPolicy* policy = g1_policy(); 5971 5972 double start_sec = os::elapsedTime(); 5973 bool non_young = true; 5974 5975 HeapRegion* cur = cs_head; 5976 int age_bound = -1; 5977 size_t rs_lengths = 0; 5978 5979 while (cur != NULL) { 5980 assert(!is_on_master_free_list(cur), "sanity"); 5981 if (non_young) { 5982 if (cur->is_young()) { 5983 double end_sec = os::elapsedTime(); 5984 double elapsed_ms = (end_sec - start_sec) * 1000.0; 5985 non_young_time_ms += elapsed_ms; 5986 5987 start_sec = os::elapsedTime(); 5988 non_young = false; 5989 } 5990 } else { 5991 if (!cur->is_young()) { 5992 double end_sec = os::elapsedTime(); 5993 double elapsed_ms = (end_sec - start_sec) * 1000.0; 5994 young_time_ms += elapsed_ms; 5995 5996 start_sec = os::elapsedTime(); 5997 non_young = true; 5998 } 5999 } 6000 6001 rs_lengths += cur->rem_set()->occupied_locked(); 6002 6003 HeapRegion* next = cur->next_in_collection_set(); 6004 assert(cur->in_collection_set(), "bad CS"); 6005 cur->set_next_in_collection_set(NULL); 6006 cur->set_in_collection_set(false); 6007 6008 if (cur->is_young()) { 6009 int index = cur->young_index_in_cset(); 6010 assert(index != -1, "invariant"); 6011 assert((uint) index < policy->young_cset_region_length(), "invariant"); 6012 size_t words_survived = _surviving_young_words[index]; 6013 cur->record_surv_words_in_group(words_survived); 6014 6015 // At this point the we have 'popped' cur from the collection set 6016 // (linked via next_in_collection_set()) but it is still in the 6017 // young list (linked via next_young_region()). Clear the 6018 // _next_young_region field. 6019 cur->set_next_young_region(NULL); 6020 } else { 6021 int index = cur->young_index_in_cset(); 6022 assert(index == -1, "invariant"); 6023 } 6024 6025 assert( (cur->is_young() && cur->young_index_in_cset() > -1) || 6026 (!cur->is_young() && cur->young_index_in_cset() == -1), 6027 "invariant" ); 6028 6029 if (!cur->evacuation_failed()) { 6030 MemRegion used_mr = cur->used_region(); 6031 6032 // And the region is empty. 6033 assert(!used_mr.is_empty(), "Should not have empty regions in a CS."); 6034 pre_used += cur->used(); 6035 free_region(cur, &local_free_list, false /* par */, true /* locked */); 6036 } else { 6037 cur->uninstall_surv_rate_group(); 6038 if (cur->is_young()) { 6039 cur->set_young_index_in_cset(-1); 6040 } 6041 cur->set_not_young(); 6042 cur->set_evacuation_failed(false); 6043 // The region is now considered to be old. 6044 _old_set.add(cur); 6045 evacuation_info.increment_collectionset_used_after(cur->used()); 6046 } 6047 cur = next; 6048 } 6049 6050 evacuation_info.set_regions_freed(local_free_list.length()); 6051 policy->record_max_rs_lengths(rs_lengths); 6052 policy->cset_regions_freed(); 6053 6054 double end_sec = os::elapsedTime(); 6055 double elapsed_ms = (end_sec - start_sec) * 1000.0; 6056 6057 if (non_young) { 6058 non_young_time_ms += elapsed_ms; 6059 } else { 6060 young_time_ms += elapsed_ms; 6061 } 6062 6063 prepend_to_freelist(&local_free_list); 6064 decrement_summary_bytes(pre_used); 6065 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms); 6066 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms); 6067 } 6068 6069 // This routine is similar to the above but does not record 6070 // any policy statistics or update free lists; we are abandoning 6071 // the current incremental collection set in preparation of a 6072 // full collection. After the full GC we will start to build up 6073 // the incremental collection set again. 6074 // This is only called when we're doing a full collection 6075 // and is immediately followed by the tearing down of the young list. 6076 6077 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) { 6078 HeapRegion* cur = cs_head; 6079 6080 while (cur != NULL) { 6081 HeapRegion* next = cur->next_in_collection_set(); 6082 assert(cur->in_collection_set(), "bad CS"); 6083 cur->set_next_in_collection_set(NULL); 6084 cur->set_in_collection_set(false); 6085 cur->set_young_index_in_cset(-1); 6086 cur = next; 6087 } 6088 } 6089 6090 void G1CollectedHeap::set_free_regions_coming() { 6091 if (G1ConcRegionFreeingVerbose) { 6092 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " 6093 "setting free regions coming"); 6094 } 6095 6096 assert(!free_regions_coming(), "pre-condition"); 6097 _free_regions_coming = true; 6098 } 6099 6100 void G1CollectedHeap::reset_free_regions_coming() { 6101 assert(free_regions_coming(), "pre-condition"); 6102 6103 { 6104 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6105 _free_regions_coming = false; 6106 SecondaryFreeList_lock->notify_all(); 6107 } 6108 6109 if (G1ConcRegionFreeingVerbose) { 6110 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " 6111 "reset free regions coming"); 6112 } 6113 } 6114 6115 void G1CollectedHeap::wait_while_free_regions_coming() { 6116 // Most of the time we won't have to wait, so let's do a quick test 6117 // first before we take the lock. 6118 if (!free_regions_coming()) { 6119 return; 6120 } 6121 6122 if (G1ConcRegionFreeingVerbose) { 6123 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " 6124 "waiting for free regions"); 6125 } 6126 6127 { 6128 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6129 while (free_regions_coming()) { 6130 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 6131 } 6132 } 6133 6134 if (G1ConcRegionFreeingVerbose) { 6135 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " 6136 "done waiting for free regions"); 6137 } 6138 } 6139 6140 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 6141 assert(heap_lock_held_for_gc(), 6142 "the heap lock should already be held by or for this thread"); 6143 _young_list->push_region(hr); 6144 } 6145 6146 class NoYoungRegionsClosure: public HeapRegionClosure { 6147 private: 6148 bool _success; 6149 public: 6150 NoYoungRegionsClosure() : _success(true) { } 6151 bool doHeapRegion(HeapRegion* r) { 6152 if (r->is_young()) { 6153 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young", 6154 r->bottom(), r->end()); 6155 _success = false; 6156 } 6157 return false; 6158 } 6159 bool success() { return _success; } 6160 }; 6161 6162 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) { 6163 bool ret = _young_list->check_list_empty(check_sample); 6164 6165 if (check_heap) { 6166 NoYoungRegionsClosure closure; 6167 heap_region_iterate(&closure); 6168 ret = ret && closure.success(); 6169 } 6170 6171 return ret; 6172 } 6173 6174 class TearDownRegionSetsClosure : public HeapRegionClosure { 6175 private: 6176 HeapRegionSet *_old_set; 6177 6178 public: 6179 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { } 6180 6181 bool doHeapRegion(HeapRegion* r) { 6182 if (r->is_empty()) { 6183 // We ignore empty regions, we'll empty the free list afterwards 6184 } else if (r->is_young()) { 6185 // We ignore young regions, we'll empty the young list afterwards 6186 } else if (r->isHumongous()) { 6187 // We ignore humongous regions, we're not tearing down the 6188 // humongous region set 6189 } else { 6190 // The rest should be old 6191 _old_set->remove(r); 6192 } 6193 return false; 6194 } 6195 6196 ~TearDownRegionSetsClosure() { 6197 assert(_old_set->is_empty(), "post-condition"); 6198 } 6199 }; 6200 6201 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) { 6202 assert_at_safepoint(true /* should_be_vm_thread */); 6203 6204 if (!free_list_only) { 6205 TearDownRegionSetsClosure cl(&_old_set); 6206 heap_region_iterate(&cl); 6207 6208 // Note that emptying the _young_list is postponed and instead done as 6209 // the first step when rebuilding the regions sets again. The reason for 6210 // this is that during a full GC string deduplication needs to know if 6211 // a collected region was young or old when the full GC was initiated. 6212 } 6213 _free_list.remove_all(); 6214 } 6215 6216 class RebuildRegionSetsClosure : public HeapRegionClosure { 6217 private: 6218 bool _free_list_only; 6219 HeapRegionSet* _old_set; 6220 FreeRegionList* _free_list; 6221 size_t _total_used; 6222 6223 public: 6224 RebuildRegionSetsClosure(bool free_list_only, 6225 HeapRegionSet* old_set, FreeRegionList* free_list) : 6226 _free_list_only(free_list_only), 6227 _old_set(old_set), _free_list(free_list), _total_used(0) { 6228 assert(_free_list->is_empty(), "pre-condition"); 6229 if (!free_list_only) { 6230 assert(_old_set->is_empty(), "pre-condition"); 6231 } 6232 } 6233 6234 bool doHeapRegion(HeapRegion* r) { 6235 if (r->continuesHumongous()) { 6236 return false; 6237 } 6238 6239 if (r->is_empty()) { 6240 // Add free regions to the free list 6241 _free_list->add_as_tail(r); 6242 } else if (!_free_list_only) { 6243 assert(!r->is_young(), "we should not come across young regions"); 6244 6245 if (r->isHumongous()) { 6246 // We ignore humongous regions, we left the humongous set unchanged 6247 } else { 6248 // The rest should be old, add them to the old set 6249 _old_set->add(r); 6250 } 6251 _total_used += r->used(); 6252 } 6253 6254 return false; 6255 } 6256 6257 size_t total_used() { 6258 return _total_used; 6259 } 6260 }; 6261 6262 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { 6263 assert_at_safepoint(true /* should_be_vm_thread */); 6264 6265 if (!free_list_only) { 6266 _young_list->empty_list(); 6267 } 6268 6269 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_free_list); 6270 heap_region_iterate(&cl); 6271 6272 if (!free_list_only) { 6273 _summary_bytes_used = cl.total_used(); 6274 } 6275 assert(_summary_bytes_used == recalculate_used(), 6276 err_msg("inconsistent _summary_bytes_used, " 6277 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT, 6278 _summary_bytes_used, recalculate_used())); 6279 } 6280 6281 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) { 6282 _refine_cte_cl->set_concurrent(concurrent); 6283 } 6284 6285 bool G1CollectedHeap::is_in_closed_subset(const void* p) const { 6286 HeapRegion* hr = heap_region_containing(p); 6287 return hr->is_in(p); 6288 } 6289 6290 // Methods for the mutator alloc region 6291 6292 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 6293 bool force) { 6294 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6295 assert(!force || g1_policy()->can_expand_young_list(), 6296 "if force is true we should be able to expand the young list"); 6297 bool young_list_full = g1_policy()->is_young_list_full(); 6298 if (force || !young_list_full) { 6299 HeapRegion* new_alloc_region = new_region(word_size, 6300 false /* is_old */, 6301 false /* do_expand */); 6302 if (new_alloc_region != NULL) { 6303 set_region_short_lived_locked(new_alloc_region); 6304 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full); 6305 check_bitmaps("Mutator Region Allocation", new_alloc_region); 6306 return new_alloc_region; 6307 } 6308 } 6309 return NULL; 6310 } 6311 6312 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 6313 size_t allocated_bytes) { 6314 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6315 assert(alloc_region->is_young(), "all mutator alloc regions should be young"); 6316 6317 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region); 6318 _summary_bytes_used += allocated_bytes; 6319 _hr_printer.retire(alloc_region); 6320 // We update the eden sizes here, when the region is retired, 6321 // instead of when it's allocated, since this is the point that its 6322 // used space has been recored in _summary_bytes_used. 6323 g1mm()->update_eden_size(); 6324 } 6325 6326 HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size, 6327 bool force) { 6328 return _g1h->new_mutator_alloc_region(word_size, force); 6329 } 6330 6331 void G1CollectedHeap::set_par_threads() { 6332 // Don't change the number of workers. Use the value previously set 6333 // in the workgroup. 6334 assert(G1CollectedHeap::use_parallel_gc_threads(), "shouldn't be here otherwise"); 6335 uint n_workers = workers()->active_workers(); 6336 assert(UseDynamicNumberOfGCThreads || 6337 n_workers == workers()->total_workers(), 6338 "Otherwise should be using the total number of workers"); 6339 if (n_workers == 0) { 6340 assert(false, "Should have been set in prior evacuation pause."); 6341 n_workers = ParallelGCThreads; 6342 workers()->set_active_workers(n_workers); 6343 } 6344 set_par_threads(n_workers); 6345 } 6346 6347 void MutatorAllocRegion::retire_region(HeapRegion* alloc_region, 6348 size_t allocated_bytes) { 6349 _g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes); 6350 } 6351 6352 // Methods for the GC alloc regions 6353 6354 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, 6355 uint count, 6356 GCAllocPurpose ap) { 6357 assert(FreeList_lock->owned_by_self(), "pre-condition"); 6358 6359 if (count < g1_policy()->max_regions(ap)) { 6360 bool survivor = (ap == GCAllocForSurvived); 6361 HeapRegion* new_alloc_region = new_region(word_size, 6362 !survivor, 6363 true /* do_expand */); 6364 if (new_alloc_region != NULL) { 6365 // We really only need to do this for old regions given that we 6366 // should never scan survivors. But it doesn't hurt to do it 6367 // for survivors too. 6368 new_alloc_region->set_saved_mark(); 6369 if (survivor) { 6370 new_alloc_region->set_survivor(); 6371 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor); 6372 check_bitmaps("Survivor Region Allocation", new_alloc_region); 6373 } else { 6374 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old); 6375 check_bitmaps("Old Region Allocation", new_alloc_region); 6376 } 6377 bool during_im = g1_policy()->during_initial_mark_pause(); 6378 new_alloc_region->note_start_of_copying(during_im); 6379 return new_alloc_region; 6380 } else { 6381 g1_policy()->note_alloc_region_limit_reached(ap); 6382 } 6383 } 6384 return NULL; 6385 } 6386 6387 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 6388 size_t allocated_bytes, 6389 GCAllocPurpose ap) { 6390 bool during_im = g1_policy()->during_initial_mark_pause(); 6391 alloc_region->note_end_of_copying(during_im); 6392 g1_policy()->record_bytes_copied_during_gc(allocated_bytes); 6393 if (ap == GCAllocForSurvived) { 6394 young_list()->add_survivor_region(alloc_region); 6395 } else { 6396 _old_set.add(alloc_region); 6397 } 6398 _hr_printer.retire(alloc_region); 6399 } 6400 6401 HeapRegion* SurvivorGCAllocRegion::allocate_new_region(size_t word_size, 6402 bool force) { 6403 assert(!force, "not supported for GC alloc regions"); 6404 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForSurvived); 6405 } 6406 6407 void SurvivorGCAllocRegion::retire_region(HeapRegion* alloc_region, 6408 size_t allocated_bytes) { 6409 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes, 6410 GCAllocForSurvived); 6411 } 6412 6413 HeapRegion* OldGCAllocRegion::allocate_new_region(size_t word_size, 6414 bool force) { 6415 assert(!force, "not supported for GC alloc regions"); 6416 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForTenured); 6417 } 6418 6419 void OldGCAllocRegion::retire_region(HeapRegion* alloc_region, 6420 size_t allocated_bytes) { 6421 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes, 6422 GCAllocForTenured); 6423 } 6424 // Heap region set verification 6425 6426 class VerifyRegionListsClosure : public HeapRegionClosure { 6427 private: 6428 HeapRegionSet* _old_set; 6429 HeapRegionSet* _humongous_set; 6430 FreeRegionList* _free_list; 6431 6432 public: 6433 HeapRegionSetCount _old_count; 6434 HeapRegionSetCount _humongous_count; 6435 HeapRegionSetCount _free_count; 6436 6437 VerifyRegionListsClosure(HeapRegionSet* old_set, 6438 HeapRegionSet* humongous_set, 6439 FreeRegionList* free_list) : 6440 _old_set(old_set), _humongous_set(humongous_set), _free_list(free_list), 6441 _old_count(), _humongous_count(), _free_count(){ } 6442 6443 bool doHeapRegion(HeapRegion* hr) { 6444 if (hr->continuesHumongous()) { 6445 return false; 6446 } 6447 6448 if (hr->is_young()) { 6449 // TODO 6450 } else if (hr->startsHumongous()) { 6451 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrs_index())); 6452 _humongous_count.increment(1u, hr->capacity()); 6453 } else if (hr->is_empty()) { 6454 assert(hr->containing_set() == _free_list, err_msg("Heap region %u is empty but not on the free list.", hr->hrs_index())); 6455 _free_count.increment(1u, hr->capacity()); 6456 } else { 6457 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrs_index())); 6458 _old_count.increment(1u, hr->capacity()); 6459 } 6460 return false; 6461 } 6462 6463 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, FreeRegionList* free_list) { 6464 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length())); 6465 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6466 old_set->total_capacity_bytes(), _old_count.capacity())); 6467 6468 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length())); 6469 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6470 humongous_set->total_capacity_bytes(), _humongous_count.capacity())); 6471 6472 guarantee(free_list->length() == _free_count.length(), err_msg("Free list count mismatch. Expected %u, actual %u.", free_list->length(), _free_count.length())); 6473 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6474 free_list->total_capacity_bytes(), _free_count.capacity())); 6475 } 6476 }; 6477 6478 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index, 6479 HeapWord* bottom) { 6480 HeapWord* end = bottom + HeapRegion::GrainWords; 6481 MemRegion mr(bottom, end); 6482 assert(_g1_reserved.contains(mr), "invariant"); 6483 // This might return NULL if the allocation fails 6484 return new HeapRegion(hrs_index, _bot_shared, mr); 6485 } 6486 6487 void G1CollectedHeap::verify_region_sets() { 6488 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6489 6490 // First, check the explicit lists. 6491 _free_list.verify_list(); 6492 { 6493 // Given that a concurrent operation might be adding regions to 6494 // the secondary free list we have to take the lock before 6495 // verifying it. 6496 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6497 _secondary_free_list.verify_list(); 6498 } 6499 6500 // If a concurrent region freeing operation is in progress it will 6501 // be difficult to correctly attributed any free regions we come 6502 // across to the correct free list given that they might belong to 6503 // one of several (free_list, secondary_free_list, any local lists, 6504 // etc.). So, if that's the case we will skip the rest of the 6505 // verification operation. Alternatively, waiting for the concurrent 6506 // operation to complete will have a non-trivial effect on the GC's 6507 // operation (no concurrent operation will last longer than the 6508 // interval between two calls to verification) and it might hide 6509 // any issues that we would like to catch during testing. 6510 if (free_regions_coming()) { 6511 return; 6512 } 6513 6514 // Make sure we append the secondary_free_list on the free_list so 6515 // that all free regions we will come across can be safely 6516 // attributed to the free_list. 6517 append_secondary_free_list_if_not_empty_with_lock(); 6518 6519 // Finally, make sure that the region accounting in the lists is 6520 // consistent with what we see in the heap. 6521 6522 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_free_list); 6523 heap_region_iterate(&cl); 6524 cl.verify_counts(&_old_set, &_humongous_set, &_free_list); 6525 } 6526 6527 // Optimized nmethod scanning 6528 6529 class RegisterNMethodOopClosure: public OopClosure { 6530 G1CollectedHeap* _g1h; 6531 nmethod* _nm; 6532 6533 template <class T> void do_oop_work(T* p) { 6534 T heap_oop = oopDesc::load_heap_oop(p); 6535 if (!oopDesc::is_null(heap_oop)) { 6536 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 6537 HeapRegion* hr = _g1h->heap_region_containing(obj); 6538 assert(!hr->continuesHumongous(), 6539 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT 6540 " starting at "HR_FORMAT, 6541 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()))); 6542 6543 // HeapRegion::add_strong_code_root() avoids adding duplicate 6544 // entries but having duplicates is OK since we "mark" nmethods 6545 // as visited when we scan the strong code root lists during the GC. 6546 hr->add_strong_code_root(_nm); 6547 assert(hr->rem_set()->strong_code_roots_list_contains(_nm), 6548 err_msg("failed to add code root "PTR_FORMAT" to remembered set of region "HR_FORMAT, 6549 _nm, HR_FORMAT_PARAMS(hr))); 6550 } 6551 } 6552 6553 public: 6554 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 6555 _g1h(g1h), _nm(nm) {} 6556 6557 void do_oop(oop* p) { do_oop_work(p); } 6558 void do_oop(narrowOop* p) { do_oop_work(p); } 6559 }; 6560 6561 class UnregisterNMethodOopClosure: public OopClosure { 6562 G1CollectedHeap* _g1h; 6563 nmethod* _nm; 6564 6565 template <class T> void do_oop_work(T* p) { 6566 T heap_oop = oopDesc::load_heap_oop(p); 6567 if (!oopDesc::is_null(heap_oop)) { 6568 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 6569 HeapRegion* hr = _g1h->heap_region_containing(obj); 6570 assert(!hr->continuesHumongous(), 6571 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT 6572 " starting at "HR_FORMAT, 6573 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()))); 6574 6575 hr->remove_strong_code_root(_nm); 6576 assert(!hr->rem_set()->strong_code_roots_list_contains(_nm), 6577 err_msg("failed to remove code root "PTR_FORMAT" of region "HR_FORMAT, 6578 _nm, HR_FORMAT_PARAMS(hr))); 6579 } 6580 } 6581 6582 public: 6583 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 6584 _g1h(g1h), _nm(nm) {} 6585 6586 void do_oop(oop* p) { do_oop_work(p); } 6587 void do_oop(narrowOop* p) { do_oop_work(p); } 6588 }; 6589 6590 void G1CollectedHeap::register_nmethod(nmethod* nm) { 6591 CollectedHeap::register_nmethod(nm); 6592 6593 guarantee(nm != NULL, "sanity"); 6594 RegisterNMethodOopClosure reg_cl(this, nm); 6595 nm->oops_do(®_cl); 6596 } 6597 6598 void G1CollectedHeap::unregister_nmethod(nmethod* nm) { 6599 CollectedHeap::unregister_nmethod(nm); 6600 6601 guarantee(nm != NULL, "sanity"); 6602 UnregisterNMethodOopClosure reg_cl(this, nm); 6603 nm->oops_do(®_cl, true); 6604 } 6605 6606 class MigrateCodeRootsHeapRegionClosure: public HeapRegionClosure { 6607 public: 6608 bool doHeapRegion(HeapRegion *hr) { 6609 assert(!hr->isHumongous(), 6610 err_msg("humongous region "HR_FORMAT" should not have been added to collection set", 6611 HR_FORMAT_PARAMS(hr))); 6612 hr->migrate_strong_code_roots(); 6613 return false; 6614 } 6615 }; 6616 6617 void G1CollectedHeap::migrate_strong_code_roots() { 6618 MigrateCodeRootsHeapRegionClosure cl; 6619 double migrate_start = os::elapsedTime(); 6620 collection_set_iterate(&cl); 6621 double migration_time_ms = (os::elapsedTime() - migrate_start) * 1000.0; 6622 g1_policy()->phase_times()->record_strong_code_root_migration_time(migration_time_ms); 6623 } 6624 6625 void G1CollectedHeap::purge_code_root_memory() { 6626 double purge_start = os::elapsedTime(); 6627 G1CodeRootSet::purge_chunks(G1CodeRootsChunkCacheKeepPercent); 6628 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0; 6629 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms); 6630 } 6631 6632 // Mark all the code roots that point into regions *not* in the 6633 // collection set. 6634 // 6635 // Note we do not want to use a "marking" CodeBlobToOopClosure while 6636 // walking the the code roots lists of regions not in the collection 6637 // set. Suppose we have an nmethod (M) that points to objects in two 6638 // separate regions - one in the collection set (R1) and one not (R2). 6639 // Using a "marking" CodeBlobToOopClosure here would result in "marking" 6640 // nmethod M when walking the code roots for R1. When we come to scan 6641 // the code roots for R2, we would see that M is already marked and it 6642 // would be skipped and the objects in R2 that are referenced from M 6643 // would not be evacuated. 6644 6645 class MarkStrongCodeRootCodeBlobClosure: public CodeBlobClosure { 6646 6647 class MarkStrongCodeRootOopClosure: public OopClosure { 6648 ConcurrentMark* _cm; 6649 HeapRegion* _hr; 6650 uint _worker_id; 6651 6652 template <class T> void do_oop_work(T* p) { 6653 T heap_oop = oopDesc::load_heap_oop(p); 6654 if (!oopDesc::is_null(heap_oop)) { 6655 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 6656 // Only mark objects in the region (which is assumed 6657 // to be not in the collection set). 6658 if (_hr->is_in(obj)) { 6659 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id); 6660 } 6661 } 6662 } 6663 6664 public: 6665 MarkStrongCodeRootOopClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id) : 6666 _cm(cm), _hr(hr), _worker_id(worker_id) { 6667 assert(!_hr->in_collection_set(), "sanity"); 6668 } 6669 6670 void do_oop(narrowOop* p) { do_oop_work(p); } 6671 void do_oop(oop* p) { do_oop_work(p); } 6672 }; 6673 6674 MarkStrongCodeRootOopClosure _oop_cl; 6675 6676 public: 6677 MarkStrongCodeRootCodeBlobClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id): 6678 _oop_cl(cm, hr, worker_id) {} 6679 6680 void do_code_blob(CodeBlob* cb) { 6681 nmethod* nm = (cb == NULL) ? NULL : cb->as_nmethod_or_null(); 6682 if (nm != NULL) { 6683 nm->oops_do(&_oop_cl); 6684 } 6685 } 6686 }; 6687 6688 class MarkStrongCodeRootsHRClosure: public HeapRegionClosure { 6689 G1CollectedHeap* _g1h; 6690 uint _worker_id; 6691 6692 public: 6693 MarkStrongCodeRootsHRClosure(G1CollectedHeap* g1h, uint worker_id) : 6694 _g1h(g1h), _worker_id(worker_id) {} 6695 6696 bool doHeapRegion(HeapRegion *hr) { 6697 HeapRegionRemSet* hrrs = hr->rem_set(); 6698 if (hr->continuesHumongous()) { 6699 // Code roots should never be attached to a continuation of a humongous region 6700 assert(hrrs->strong_code_roots_list_length() == 0, 6701 err_msg("code roots should never be attached to continuations of humongous region "HR_FORMAT 6702 " starting at "HR_FORMAT", but has "SIZE_FORMAT, 6703 HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()), 6704 hrrs->strong_code_roots_list_length())); 6705 return false; 6706 } 6707 6708 if (hr->in_collection_set()) { 6709 // Don't mark code roots into regions in the collection set here. 6710 // They will be marked when we scan them. 6711 return false; 6712 } 6713 6714 MarkStrongCodeRootCodeBlobClosure cb_cl(_g1h->concurrent_mark(), hr, _worker_id); 6715 hr->strong_code_roots_do(&cb_cl); 6716 return false; 6717 } 6718 }; 6719 6720 void G1CollectedHeap::mark_strong_code_roots(uint worker_id) { 6721 MarkStrongCodeRootsHRClosure cl(this, worker_id); 6722 if (G1CollectedHeap::use_parallel_gc_threads()) { 6723 heap_region_par_iterate_chunked(&cl, 6724 worker_id, 6725 workers()->active_workers(), 6726 HeapRegion::ParMarkRootClaimValue); 6727 } else { 6728 heap_region_iterate(&cl); 6729 } 6730 } 6731 6732 class RebuildStrongCodeRootClosure: public CodeBlobClosure { 6733 G1CollectedHeap* _g1h; 6734 6735 public: 6736 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) : 6737 _g1h(g1h) {} 6738 6739 void do_code_blob(CodeBlob* cb) { 6740 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL; 6741 if (nm == NULL) { 6742 return; 6743 } 6744 6745 if (ScavengeRootsInCode) { 6746 _g1h->register_nmethod(nm); 6747 } 6748 } 6749 }; 6750 6751 void G1CollectedHeap::rebuild_strong_code_roots() { 6752 RebuildStrongCodeRootClosure blob_cl(this); 6753 CodeCache::blobs_do(&blob_cl); 6754 }