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 #include "precompiled.hpp" 26 #include "code/codeCache.hpp" 27 #include "code/icBuffer.hpp" 28 #include "gc_implementation/g1/bufferingOopClosure.hpp" 29 #include "gc_implementation/g1/concurrentG1Refine.hpp" 30 #include "gc_implementation/g1/concurrentG1RefineThread.hpp" 31 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp" 32 #include "gc_implementation/g1/g1AllocRegion.inline.hpp" 33 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp" 34 #include "gc_implementation/g1/g1CollectorPolicy.hpp" 35 #include "gc_implementation/g1/g1ErgoVerbose.hpp" 36 #include "gc_implementation/g1/g1EvacFailure.hpp" 37 #include "gc_implementation/g1/g1GCPhaseTimes.hpp" 38 #include "gc_implementation/g1/g1Log.hpp" 39 #include "gc_implementation/g1/g1MarkSweep.hpp" 40 #include "gc_implementation/g1/g1OopClosures.inline.hpp" 41 #include "gc_implementation/g1/g1RemSet.inline.hpp" 42 #include "gc_implementation/g1/g1StringDedup.hpp" 43 #include "gc_implementation/g1/g1YCTypes.hpp" 44 #include "gc_implementation/g1/heapRegion.inline.hpp" 45 #include "gc_implementation/g1/heapRegionRemSet.hpp" 46 #include "gc_implementation/g1/heapRegionSeq.inline.hpp" 47 #include "gc_implementation/g1/vm_operations_g1.hpp" 48 #include "gc_implementation/shared/gcHeapSummary.hpp" 49 #include "gc_implementation/shared/gcTimer.hpp" 50 #include "gc_implementation/shared/gcTrace.hpp" 51 #include "gc_implementation/shared/gcTraceTime.hpp" 52 #include "gc_implementation/shared/isGCActiveMark.hpp" 53 #include "memory/gcLocker.inline.hpp" 54 #include "memory/generationSpec.hpp" 55 #include "memory/iterator.hpp" 56 #include "memory/referenceProcessor.hpp" 57 #include "oops/oop.inline.hpp" 58 #include "oops/oop.pcgc.inline.hpp" 59 #include "runtime/vmThread.hpp" 60 #include "utilities/globalDefinitions.hpp" 61 #include "utilities/ticks.hpp" 62 63 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0; 64 65 // turn it on so that the contents of the young list (scan-only / 66 // to-be-collected) are printed at "strategic" points before / during 67 // / after the collection --- this is useful for debugging 68 #define YOUNG_LIST_VERBOSE 0 69 // CURRENT STATUS 70 // This file is under construction. Search for "FIXME". 71 72 // INVARIANTS/NOTES 73 // 74 // All allocation activity covered by the G1CollectedHeap interface is 75 // serialized by acquiring the HeapLock. This happens in mem_allocate 76 // and allocate_new_tlab, which are the "entry" points to the 77 // allocation code from the rest of the JVM. (Note that this does not 78 // apply to TLAB allocation, which is not part of this interface: it 79 // is done by clients of this interface.) 80 81 // Notes on implementation of parallelism in different tasks. 82 // 83 // G1ParVerifyTask uses heap_region_par_iterate_chunked() for parallelism. 84 // The number of GC workers is passed to heap_region_par_iterate_chunked(). 85 // It does use run_task() which sets _n_workers in the task. 86 // G1ParTask executes g1_process_strong_roots() -> 87 // SharedHeap::process_strong_roots() which calls eventually to 88 // CardTableModRefBS::par_non_clean_card_iterate_work() which uses 89 // SequentialSubTasksDone. SharedHeap::process_strong_roots() also 90 // directly uses SubTasksDone (_process_strong_tasks field in SharedHeap). 91 // 92 93 // Local to this file. 94 95 class RefineCardTableEntryClosure: public CardTableEntryClosure { 96 bool _concurrent; 97 public: 98 RefineCardTableEntryClosure() : _concurrent(true) { } 99 100 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 101 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false); 102 // This path is executed by the concurrent refine or mutator threads, 103 // concurrently, and so we do not care if card_ptr contains references 104 // that point into the collection set. 105 assert(!oops_into_cset, "should be"); 106 107 if (_concurrent && SuspendibleThreadSet::should_yield()) { 108 // Caller will actually yield. 109 return false; 110 } 111 // Otherwise, we finished successfully; return true. 112 return true; 113 } 114 115 void set_concurrent(bool b) { _concurrent = b; } 116 }; 117 118 119 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure { 120 size_t _num_processed; 121 CardTableModRefBS* _ctbs; 122 int _histo[256]; 123 124 public: 125 ClearLoggedCardTableEntryClosure() : 126 _num_processed(0), _ctbs(G1CollectedHeap::heap()->g1_barrier_set()) 127 { 128 for (int i = 0; i < 256; i++) _histo[i] = 0; 129 } 130 131 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 132 unsigned char* ujb = (unsigned char*)card_ptr; 133 int ind = (int)(*ujb); 134 _histo[ind]++; 135 136 *card_ptr = (jbyte)CardTableModRefBS::clean_card_val(); 137 _num_processed++; 138 139 return true; 140 } 141 142 size_t num_processed() { return _num_processed; } 143 144 void print_histo() { 145 gclog_or_tty->print_cr("Card table value histogram:"); 146 for (int i = 0; i < 256; i++) { 147 if (_histo[i] != 0) { 148 gclog_or_tty->print_cr(" %d: %d", i, _histo[i]); 149 } 150 } 151 } 152 }; 153 154 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure { 155 private: 156 size_t _num_processed; 157 158 public: 159 RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { } 160 161 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 162 *card_ptr = CardTableModRefBS::dirty_card_val(); 163 _num_processed++; 164 return true; 165 } 166 167 size_t num_processed() const { return _num_processed; } 168 }; 169 170 YoungList::YoungList(G1CollectedHeap* g1h) : 171 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0), 172 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) { 173 guarantee(check_list_empty(false), "just making sure..."); 174 } 175 176 void YoungList::push_region(HeapRegion *hr) { 177 assert(!hr->is_young(), "should not already be young"); 178 assert(hr->get_next_young_region() == NULL, "cause it should!"); 179 180 hr->set_next_young_region(_head); 181 _head = hr; 182 183 _g1h->g1_policy()->set_region_eden(hr, (int) _length); 184 ++_length; 185 } 186 187 void YoungList::add_survivor_region(HeapRegion* hr) { 188 assert(hr->is_survivor(), "should be flagged as survivor region"); 189 assert(hr->get_next_young_region() == NULL, "cause it should!"); 190 191 hr->set_next_young_region(_survivor_head); 192 if (_survivor_head == NULL) { 193 _survivor_tail = hr; 194 } 195 _survivor_head = hr; 196 ++_survivor_length; 197 } 198 199 void YoungList::empty_list(HeapRegion* list) { 200 while (list != NULL) { 201 HeapRegion* next = list->get_next_young_region(); 202 list->set_next_young_region(NULL); 203 list->uninstall_surv_rate_group(); 204 list->set_not_young(); 205 list = next; 206 } 207 } 208 209 void YoungList::empty_list() { 210 assert(check_list_well_formed(), "young list should be well formed"); 211 212 empty_list(_head); 213 _head = NULL; 214 _length = 0; 215 216 empty_list(_survivor_head); 217 _survivor_head = NULL; 218 _survivor_tail = NULL; 219 _survivor_length = 0; 220 221 _last_sampled_rs_lengths = 0; 222 223 assert(check_list_empty(false), "just making sure..."); 224 } 225 226 bool YoungList::check_list_well_formed() { 227 bool ret = true; 228 229 uint length = 0; 230 HeapRegion* curr = _head; 231 HeapRegion* last = NULL; 232 while (curr != NULL) { 233 if (!curr->is_young()) { 234 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" " 235 "incorrectly tagged (y: %d, surv: %d)", 236 curr->bottom(), curr->end(), 237 curr->is_young(), curr->is_survivor()); 238 ret = false; 239 } 240 ++length; 241 last = curr; 242 curr = curr->get_next_young_region(); 243 } 244 ret = ret && (length == _length); 245 246 if (!ret) { 247 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!"); 248 gclog_or_tty->print_cr("### list has %u entries, _length is %u", 249 length, _length); 250 } 251 252 return ret; 253 } 254 255 bool YoungList::check_list_empty(bool check_sample) { 256 bool ret = true; 257 258 if (_length != 0) { 259 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u", 260 _length); 261 ret = false; 262 } 263 if (check_sample && _last_sampled_rs_lengths != 0) { 264 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths"); 265 ret = false; 266 } 267 if (_head != NULL) { 268 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head"); 269 ret = false; 270 } 271 if (!ret) { 272 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty"); 273 } 274 275 return ret; 276 } 277 278 void 279 YoungList::rs_length_sampling_init() { 280 _sampled_rs_lengths = 0; 281 _curr = _head; 282 } 283 284 bool 285 YoungList::rs_length_sampling_more() { 286 return _curr != NULL; 287 } 288 289 void 290 YoungList::rs_length_sampling_next() { 291 assert( _curr != NULL, "invariant" ); 292 size_t rs_length = _curr->rem_set()->occupied(); 293 294 _sampled_rs_lengths += rs_length; 295 296 // The current region may not yet have been added to the 297 // incremental collection set (it gets added when it is 298 // retired as the current allocation region). 299 if (_curr->in_collection_set()) { 300 // Update the collection set policy information for this region 301 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length); 302 } 303 304 _curr = _curr->get_next_young_region(); 305 if (_curr == NULL) { 306 _last_sampled_rs_lengths = _sampled_rs_lengths; 307 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths); 308 } 309 } 310 311 void 312 YoungList::reset_auxilary_lists() { 313 guarantee( is_empty(), "young list should be empty" ); 314 assert(check_list_well_formed(), "young list should be well formed"); 315 316 // Add survivor regions to SurvRateGroup. 317 _g1h->g1_policy()->note_start_adding_survivor_regions(); 318 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */); 319 320 int young_index_in_cset = 0; 321 for (HeapRegion* curr = _survivor_head; 322 curr != NULL; 323 curr = curr->get_next_young_region()) { 324 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset); 325 326 // The region is a non-empty survivor so let's add it to 327 // the incremental collection set for the next evacuation 328 // pause. 329 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr); 330 young_index_in_cset += 1; 331 } 332 assert((uint) young_index_in_cset == _survivor_length, "post-condition"); 333 _g1h->g1_policy()->note_stop_adding_survivor_regions(); 334 335 _head = _survivor_head; 336 _length = _survivor_length; 337 if (_survivor_head != NULL) { 338 assert(_survivor_tail != NULL, "cause it shouldn't be"); 339 assert(_survivor_length > 0, "invariant"); 340 _survivor_tail->set_next_young_region(NULL); 341 } 342 343 // Don't clear the survivor list handles until the start of 344 // the next evacuation pause - we need it in order to re-tag 345 // the survivor regions from this evacuation pause as 'young' 346 // at the start of the next. 347 348 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */); 349 350 assert(check_list_well_formed(), "young list should be well formed"); 351 } 352 353 void YoungList::print() { 354 HeapRegion* lists[] = {_head, _survivor_head}; 355 const char* names[] = {"YOUNG", "SURVIVOR"}; 356 357 for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) { 358 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]); 359 HeapRegion *curr = lists[list]; 360 if (curr == NULL) 361 gclog_or_tty->print_cr(" empty"); 362 while (curr != NULL) { 363 gclog_or_tty->print_cr(" "HR_FORMAT", P: "PTR_FORMAT "N: "PTR_FORMAT", age: %4d", 364 HR_FORMAT_PARAMS(curr), 365 curr->prev_top_at_mark_start(), 366 curr->next_top_at_mark_start(), 367 curr->age_in_surv_rate_group_cond()); 368 curr = curr->get_next_young_region(); 369 } 370 } 371 372 gclog_or_tty->print_cr(""); 373 } 374 375 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr) 376 { 377 // Claim the right to put the region on the dirty cards region list 378 // by installing a self pointer. 379 HeapRegion* next = hr->get_next_dirty_cards_region(); 380 if (next == NULL) { 381 HeapRegion* res = (HeapRegion*) 382 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(), 383 NULL); 384 if (res == NULL) { 385 HeapRegion* head; 386 do { 387 // Put the region to the dirty cards region list. 388 head = _dirty_cards_region_list; 389 next = (HeapRegion*) 390 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head); 391 if (next == head) { 392 assert(hr->get_next_dirty_cards_region() == hr, 393 "hr->get_next_dirty_cards_region() != hr"); 394 if (next == NULL) { 395 // The last region in the list points to itself. 396 hr->set_next_dirty_cards_region(hr); 397 } else { 398 hr->set_next_dirty_cards_region(next); 399 } 400 } 401 } while (next != head); 402 } 403 } 404 } 405 406 HeapRegion* G1CollectedHeap::pop_dirty_cards_region() 407 { 408 HeapRegion* head; 409 HeapRegion* hr; 410 do { 411 head = _dirty_cards_region_list; 412 if (head == NULL) { 413 return NULL; 414 } 415 HeapRegion* new_head = head->get_next_dirty_cards_region(); 416 if (head == new_head) { 417 // The last region. 418 new_head = NULL; 419 } 420 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list, 421 head); 422 } while (hr != head); 423 assert(hr != NULL, "invariant"); 424 hr->set_next_dirty_cards_region(NULL); 425 return hr; 426 } 427 428 void G1CollectedHeap::stop_conc_gc_threads() { 429 _cg1r->stop(); 430 _cmThread->stop(); 431 if (G1StringDedup::is_enabled()) { 432 G1StringDedup::stop(); 433 } 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"); 771 772 assert(first_hr->used() == word_size * HeapWordSize, "invariant"); 773 _summary_bytes_used += first_hr->used(); 774 _humongous_set.add(first_hr); 775 776 return new_obj; 777 } 778 779 // If could fit into free regions w/o expansion, try. 780 // Otherwise, if can expand, do so. 781 // Otherwise, if using ex regions might help, try with ex given back. 782 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) { 783 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 784 785 verify_region_sets_optional(); 786 787 size_t word_size_rounded = round_to(word_size, HeapRegion::GrainWords); 788 uint num_regions = (uint) (word_size_rounded / HeapRegion::GrainWords); 789 uint x_num = expansion_regions(); 790 uint fs = _hrs.free_suffix(); 791 uint first = humongous_obj_allocate_find_first(num_regions, word_size); 792 if (first == G1_NULL_HRS_INDEX) { 793 // The only thing we can do now is attempt expansion. 794 if (fs + x_num >= num_regions) { 795 // If the number of regions we're trying to allocate for this 796 // object is at most the number of regions in the free suffix, 797 // then the call to humongous_obj_allocate_find_first() above 798 // should have succeeded and we wouldn't be here. 799 // 800 // We should only be trying to expand when the free suffix is 801 // not sufficient for the object _and_ we have some expansion 802 // room available. 803 assert(num_regions > fs, "earlier allocation should have succeeded"); 804 805 ergo_verbose1(ErgoHeapSizing, 806 "attempt heap expansion", 807 ergo_format_reason("humongous allocation request failed") 808 ergo_format_byte("allocation request"), 809 word_size * HeapWordSize); 810 if (expand((num_regions - fs) * HeapRegion::GrainBytes)) { 811 // Even though the heap was expanded, it might not have 812 // reached the desired size. So, we cannot assume that the 813 // allocation will succeed. 814 first = humongous_obj_allocate_find_first(num_regions, word_size); 815 } 816 } 817 } 818 819 HeapWord* result = NULL; 820 if (first != G1_NULL_HRS_INDEX) { 821 result = 822 humongous_obj_allocate_initialize_regions(first, num_regions, word_size); 823 assert(result != NULL, "it should always return a valid result"); 824 825 // A successful humongous object allocation changes the used space 826 // information of the old generation so we need to recalculate the 827 // sizes and update the jstat counters here. 828 g1mm()->update_sizes(); 829 } 830 831 verify_region_sets_optional(); 832 833 return result; 834 } 835 836 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) { 837 assert_heap_not_locked_and_not_at_safepoint(); 838 assert(!isHumongous(word_size), "we do not allow humongous TLABs"); 839 840 unsigned int dummy_gc_count_before; 841 int dummy_gclocker_retry_count = 0; 842 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count); 843 } 844 845 HeapWord* 846 G1CollectedHeap::mem_allocate(size_t word_size, 847 bool* gc_overhead_limit_was_exceeded) { 848 assert_heap_not_locked_and_not_at_safepoint(); 849 850 // Loop until the allocation is satisfied, or unsatisfied after GC. 851 for (int try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 852 unsigned int gc_count_before; 853 854 HeapWord* result = NULL; 855 if (!isHumongous(word_size)) { 856 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count); 857 } else { 858 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count); 859 } 860 if (result != NULL) { 861 return result; 862 } 863 864 // Create the garbage collection operation... 865 VM_G1CollectForAllocation op(gc_count_before, word_size); 866 // ...and get the VM thread to execute it. 867 VMThread::execute(&op); 868 869 if (op.prologue_succeeded() && op.pause_succeeded()) { 870 // If the operation was successful we'll return the result even 871 // if it is NULL. If the allocation attempt failed immediately 872 // after a Full GC, it's unlikely we'll be able to allocate now. 873 HeapWord* result = op.result(); 874 if (result != NULL && !isHumongous(word_size)) { 875 // Allocations that take place on VM operations do not do any 876 // card dirtying and we have to do it here. We only have to do 877 // this for non-humongous allocations, though. 878 dirty_young_block(result, word_size); 879 } 880 return result; 881 } else { 882 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 883 return NULL; 884 } 885 assert(op.result() == NULL, 886 "the result should be NULL if the VM op did not succeed"); 887 } 888 889 // Give a warning if we seem to be looping forever. 890 if ((QueuedAllocationWarningCount > 0) && 891 (try_count % QueuedAllocationWarningCount == 0)) { 892 warning("G1CollectedHeap::mem_allocate retries %d times", try_count); 893 } 894 } 895 896 ShouldNotReachHere(); 897 return NULL; 898 } 899 900 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size, 901 unsigned int *gc_count_before_ret, 902 int* gclocker_retry_count_ret) { 903 // Make sure you read the note in attempt_allocation_humongous(). 904 905 assert_heap_not_locked_and_not_at_safepoint(); 906 assert(!isHumongous(word_size), "attempt_allocation_slow() should not " 907 "be called for humongous allocation requests"); 908 909 // We should only get here after the first-level allocation attempt 910 // (attempt_allocation()) failed to allocate. 911 912 // We will loop until a) we manage to successfully perform the 913 // allocation or b) we successfully schedule a collection which 914 // fails to perform the allocation. b) is the only case when we'll 915 // return NULL. 916 HeapWord* result = NULL; 917 for (int try_count = 1; /* we'll return */; try_count += 1) { 918 bool should_try_gc; 919 unsigned int gc_count_before; 920 921 { 922 MutexLockerEx x(Heap_lock); 923 924 result = _mutator_alloc_region.attempt_allocation_locked(word_size, 925 false /* bot_updates */); 926 if (result != NULL) { 927 return result; 928 } 929 930 // If we reach here, attempt_allocation_locked() above failed to 931 // allocate a new region. So the mutator alloc region should be NULL. 932 assert(_mutator_alloc_region.get() == NULL, "only way to get here"); 933 934 if (GC_locker::is_active_and_needs_gc()) { 935 if (g1_policy()->can_expand_young_list()) { 936 // No need for an ergo verbose message here, 937 // can_expand_young_list() does this when it returns true. 938 result = _mutator_alloc_region.attempt_allocation_force(word_size, 939 false /* bot_updates */); 940 if (result != NULL) { 941 return result; 942 } 943 } 944 should_try_gc = false; 945 } else { 946 // The GCLocker may not be active but the GCLocker initiated 947 // GC may not yet have been performed (GCLocker::needs_gc() 948 // returns true). In this case we do not try this GC and 949 // wait until the GCLocker initiated GC is performed, and 950 // then retry the allocation. 951 if (GC_locker::needs_gc()) { 952 should_try_gc = false; 953 } else { 954 // Read the GC count while still holding the Heap_lock. 955 gc_count_before = total_collections(); 956 should_try_gc = true; 957 } 958 } 959 } 960 961 if (should_try_gc) { 962 bool succeeded; 963 result = do_collection_pause(word_size, gc_count_before, &succeeded, 964 GCCause::_g1_inc_collection_pause); 965 if (result != NULL) { 966 assert(succeeded, "only way to get back a non-NULL result"); 967 return result; 968 } 969 970 if (succeeded) { 971 // If we get here we successfully scheduled a collection which 972 // failed to allocate. No point in trying to allocate 973 // further. We'll just return NULL. 974 MutexLockerEx x(Heap_lock); 975 *gc_count_before_ret = total_collections(); 976 return NULL; 977 } 978 } else { 979 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { 980 MutexLockerEx x(Heap_lock); 981 *gc_count_before_ret = total_collections(); 982 return NULL; 983 } 984 // The GCLocker is either active or the GCLocker initiated 985 // GC has not yet been performed. Stall until it is and 986 // then retry the allocation. 987 GC_locker::stall_until_clear(); 988 (*gclocker_retry_count_ret) += 1; 989 } 990 991 // We can reach here if we were unsuccessful in scheduling a 992 // collection (because another thread beat us to it) or if we were 993 // stalled due to the GC locker. In either can we should retry the 994 // allocation attempt in case another thread successfully 995 // performed a collection and reclaimed enough space. We do the 996 // first attempt (without holding the Heap_lock) here and the 997 // follow-on attempt will be at the start of the next loop 998 // iteration (after taking the Heap_lock). 999 result = _mutator_alloc_region.attempt_allocation(word_size, 1000 false /* bot_updates */); 1001 if (result != NULL) { 1002 return result; 1003 } 1004 1005 // Give a warning if we seem to be looping forever. 1006 if ((QueuedAllocationWarningCount > 0) && 1007 (try_count % QueuedAllocationWarningCount == 0)) { 1008 warning("G1CollectedHeap::attempt_allocation_slow() " 1009 "retries %d times", try_count); 1010 } 1011 } 1012 1013 ShouldNotReachHere(); 1014 return NULL; 1015 } 1016 1017 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size, 1018 unsigned int * gc_count_before_ret, 1019 int* gclocker_retry_count_ret) { 1020 // The structure of this method has a lot of similarities to 1021 // attempt_allocation_slow(). The reason these two were not merged 1022 // into a single one is that such a method would require several "if 1023 // allocation is not humongous do this, otherwise do that" 1024 // conditional paths which would obscure its flow. In fact, an early 1025 // version of this code did use a unified method which was harder to 1026 // follow and, as a result, it had subtle bugs that were hard to 1027 // track down. So keeping these two methods separate allows each to 1028 // be more readable. It will be good to keep these two in sync as 1029 // much as possible. 1030 1031 assert_heap_not_locked_and_not_at_safepoint(); 1032 assert(isHumongous(word_size), "attempt_allocation_humongous() " 1033 "should only be called for humongous allocations"); 1034 1035 // Humongous objects can exhaust the heap quickly, so we should check if we 1036 // need to start a marking cycle at each humongous object allocation. We do 1037 // the check before we do the actual allocation. The reason for doing it 1038 // before the allocation is that we avoid having to keep track of the newly 1039 // allocated memory while we do a GC. 1040 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation", 1041 word_size)) { 1042 collect(GCCause::_g1_humongous_allocation); 1043 } 1044 1045 // We will loop until a) we manage to successfully perform the 1046 // allocation or b) we successfully schedule a collection which 1047 // fails to perform the allocation. b) is the only case when we'll 1048 // return NULL. 1049 HeapWord* result = NULL; 1050 for (int try_count = 1; /* we'll return */; try_count += 1) { 1051 bool should_try_gc; 1052 unsigned int gc_count_before; 1053 1054 { 1055 MutexLockerEx x(Heap_lock); 1056 1057 // Given that humongous objects are not allocated in young 1058 // regions, we'll first try to do the allocation without doing a 1059 // collection hoping that there's enough space in the heap. 1060 result = humongous_obj_allocate(word_size); 1061 if (result != NULL) { 1062 return result; 1063 } 1064 1065 if (GC_locker::is_active_and_needs_gc()) { 1066 should_try_gc = false; 1067 } else { 1068 // The GCLocker may not be active but the GCLocker initiated 1069 // GC may not yet have been performed (GCLocker::needs_gc() 1070 // returns true). In this case we do not try this GC and 1071 // wait until the GCLocker initiated GC is performed, and 1072 // then retry the allocation. 1073 if (GC_locker::needs_gc()) { 1074 should_try_gc = false; 1075 } else { 1076 // Read the GC count while still holding the Heap_lock. 1077 gc_count_before = total_collections(); 1078 should_try_gc = true; 1079 } 1080 } 1081 } 1082 1083 if (should_try_gc) { 1084 // If we failed to allocate the humongous object, we should try to 1085 // do a collection pause (if we're allowed) in case it reclaims 1086 // enough space for the allocation to succeed after the pause. 1087 1088 bool succeeded; 1089 result = do_collection_pause(word_size, gc_count_before, &succeeded, 1090 GCCause::_g1_humongous_allocation); 1091 if (result != NULL) { 1092 assert(succeeded, "only way to get back a non-NULL result"); 1093 return result; 1094 } 1095 1096 if (succeeded) { 1097 // If we get here we successfully scheduled a collection which 1098 // failed to allocate. No point in trying to allocate 1099 // further. We'll just return NULL. 1100 MutexLockerEx x(Heap_lock); 1101 *gc_count_before_ret = total_collections(); 1102 return NULL; 1103 } 1104 } else { 1105 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { 1106 MutexLockerEx x(Heap_lock); 1107 *gc_count_before_ret = total_collections(); 1108 return NULL; 1109 } 1110 // The GCLocker is either active or the GCLocker initiated 1111 // GC has not yet been performed. Stall until it is and 1112 // then retry the allocation. 1113 GC_locker::stall_until_clear(); 1114 (*gclocker_retry_count_ret) += 1; 1115 } 1116 1117 // We can reach here if we were unsuccessful in scheduling a 1118 // collection (because another thread beat us to it) or if we were 1119 // stalled due to the GC locker. In either can we should retry the 1120 // allocation attempt in case another thread successfully 1121 // performed a collection and reclaimed enough space. Give a 1122 // warning if we seem to be looping forever. 1123 1124 if ((QueuedAllocationWarningCount > 0) && 1125 (try_count % QueuedAllocationWarningCount == 0)) { 1126 warning("G1CollectedHeap::attempt_allocation_humongous() " 1127 "retries %d times", try_count); 1128 } 1129 } 1130 1131 ShouldNotReachHere(); 1132 return NULL; 1133 } 1134 1135 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size, 1136 bool expect_null_mutator_alloc_region) { 1137 assert_at_safepoint(true /* should_be_vm_thread */); 1138 assert(_mutator_alloc_region.get() == NULL || 1139 !expect_null_mutator_alloc_region, 1140 "the current alloc region was unexpectedly found to be non-NULL"); 1141 1142 if (!isHumongous(word_size)) { 1143 return _mutator_alloc_region.attempt_allocation_locked(word_size, 1144 false /* bot_updates */); 1145 } else { 1146 HeapWord* result = humongous_obj_allocate(word_size); 1147 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) { 1148 g1_policy()->set_initiate_conc_mark_if_possible(); 1149 } 1150 return result; 1151 } 1152 1153 ShouldNotReachHere(); 1154 } 1155 1156 class PostMCRemSetClearClosure: public HeapRegionClosure { 1157 G1CollectedHeap* _g1h; 1158 ModRefBarrierSet* _mr_bs; 1159 public: 1160 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) : 1161 _g1h(g1h), _mr_bs(mr_bs) {} 1162 1163 bool doHeapRegion(HeapRegion* r) { 1164 HeapRegionRemSet* hrrs = r->rem_set(); 1165 1166 if (r->continuesHumongous()) { 1167 // We'll assert that the strong code root list and RSet is empty 1168 assert(hrrs->strong_code_roots_list_length() == 0, "sanity"); 1169 assert(hrrs->occupied() == 0, "RSet should be empty"); 1170 return false; 1171 } 1172 1173 _g1h->reset_gc_time_stamps(r); 1174 hrrs->clear(); 1175 // You might think here that we could clear just the cards 1176 // corresponding to the used region. But no: if we leave a dirty card 1177 // in a region we might allocate into, then it would prevent that card 1178 // from being enqueued, and cause it to be missed. 1179 // Re: the performance cost: we shouldn't be doing full GC anyway! 1180 _mr_bs->clear(MemRegion(r->bottom(), r->end())); 1181 1182 return false; 1183 } 1184 }; 1185 1186 void G1CollectedHeap::clear_rsets_post_compaction() { 1187 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set()); 1188 heap_region_iterate(&rs_clear); 1189 } 1190 1191 class RebuildRSOutOfRegionClosure: public HeapRegionClosure { 1192 G1CollectedHeap* _g1h; 1193 UpdateRSOopClosure _cl; 1194 int _worker_i; 1195 public: 1196 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) : 1197 _cl(g1->g1_rem_set(), worker_i), 1198 _worker_i(worker_i), 1199 _g1h(g1) 1200 { } 1201 1202 bool doHeapRegion(HeapRegion* r) { 1203 if (!r->continuesHumongous()) { 1204 _cl.set_from(r); 1205 r->oop_iterate(&_cl); 1206 } 1207 return false; 1208 } 1209 }; 1210 1211 class ParRebuildRSTask: public AbstractGangTask { 1212 G1CollectedHeap* _g1; 1213 public: 1214 ParRebuildRSTask(G1CollectedHeap* g1) 1215 : AbstractGangTask("ParRebuildRSTask"), 1216 _g1(g1) 1217 { } 1218 1219 void work(uint worker_id) { 1220 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id); 1221 _g1->heap_region_par_iterate_chunked(&rebuild_rs, worker_id, 1222 _g1->workers()->active_workers(), 1223 HeapRegion::RebuildRSClaimValue); 1224 } 1225 }; 1226 1227 class PostCompactionPrinterClosure: public HeapRegionClosure { 1228 private: 1229 G1HRPrinter* _hr_printer; 1230 public: 1231 bool doHeapRegion(HeapRegion* hr) { 1232 assert(!hr->is_young(), "not expecting to find young regions"); 1233 // We only generate output for non-empty regions. 1234 if (!hr->is_empty()) { 1235 if (!hr->isHumongous()) { 1236 _hr_printer->post_compaction(hr, G1HRPrinter::Old); 1237 } else if (hr->startsHumongous()) { 1238 if (hr->region_num() == 1) { 1239 // single humongous region 1240 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous); 1241 } else { 1242 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous); 1243 } 1244 } else { 1245 assert(hr->continuesHumongous(), "only way to get here"); 1246 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous); 1247 } 1248 } 1249 return false; 1250 } 1251 1252 PostCompactionPrinterClosure(G1HRPrinter* hr_printer) 1253 : _hr_printer(hr_printer) { } 1254 }; 1255 1256 void G1CollectedHeap::print_hrs_post_compaction() { 1257 PostCompactionPrinterClosure cl(hr_printer()); 1258 heap_region_iterate(&cl); 1259 } 1260 1261 bool G1CollectedHeap::do_collection(bool explicit_gc, 1262 bool clear_all_soft_refs, 1263 size_t word_size) { 1264 assert_at_safepoint(true /* should_be_vm_thread */); 1265 1266 if (GC_locker::check_active_before_gc()) { 1267 return false; 1268 } 1269 1270 STWGCTimer* gc_timer = G1MarkSweep::gc_timer(); 1271 gc_timer->register_gc_start(); 1272 1273 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer(); 1274 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start()); 1275 1276 SvcGCMarker sgcm(SvcGCMarker::FULL); 1277 ResourceMark rm; 1278 1279 print_heap_before_gc(); 1280 trace_heap_before_gc(gc_tracer); 1281 1282 size_t metadata_prev_used = MetaspaceAux::used_bytes(); 1283 1284 verify_region_sets_optional(); 1285 1286 const bool do_clear_all_soft_refs = clear_all_soft_refs || 1287 collector_policy()->should_clear_all_soft_refs(); 1288 1289 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy()); 1290 1291 { 1292 IsGCActiveMark x; 1293 1294 // Timing 1295 assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant"); 1296 gclog_or_tty->date_stamp(G1Log::fine() && PrintGCDateStamps); 1297 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty); 1298 1299 { 1300 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL); 1301 TraceCollectorStats tcs(g1mm()->full_collection_counters()); 1302 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause()); 1303 1304 double start = os::elapsedTime(); 1305 g1_policy()->record_full_collection_start(); 1306 1307 // Note: When we have a more flexible GC logging framework that 1308 // allows us to add optional attributes to a GC log record we 1309 // could consider timing and reporting how long we wait in the 1310 // following two methods. 1311 wait_while_free_regions_coming(); 1312 // If we start the compaction before the CM threads finish 1313 // scanning the root regions we might trip them over as we'll 1314 // be moving objects / updating references. So let's wait until 1315 // they are done. By telling them to abort, they should complete 1316 // early. 1317 _cm->root_regions()->abort(); 1318 _cm->root_regions()->wait_until_scan_finished(); 1319 append_secondary_free_list_if_not_empty_with_lock(); 1320 1321 gc_prologue(true); 1322 increment_total_collections(true /* full gc */); 1323 increment_old_marking_cycles_started(); 1324 1325 assert(used() == recalculate_used(), "Should be equal"); 1326 1327 verify_before_gc(); 1328 1329 pre_full_gc_dump(gc_timer); 1330 1331 COMPILER2_PRESENT(DerivedPointerTable::clear()); 1332 1333 // Disable discovery and empty the discovered lists 1334 // for the CM ref processor. 1335 ref_processor_cm()->disable_discovery(); 1336 ref_processor_cm()->abandon_partial_discovery(); 1337 ref_processor_cm()->verify_no_references_recorded(); 1338 1339 // Abandon current iterations of concurrent marking and concurrent 1340 // refinement, if any are in progress. We have to do this before 1341 // wait_until_scan_finished() below. 1342 concurrent_mark()->abort(); 1343 1344 // Make sure we'll choose a new allocation region afterwards. 1345 release_mutator_alloc_region(); 1346 abandon_gc_alloc_regions(); 1347 g1_rem_set()->cleanupHRRS(); 1348 1349 // We should call this after we retire any currently active alloc 1350 // regions so that all the ALLOC / RETIRE events are generated 1351 // before the start GC event. 1352 _hr_printer.start_gc(true /* full */, (size_t) total_collections()); 1353 1354 // We may have added regions to the current incremental collection 1355 // set between the last GC or pause and now. We need to clear the 1356 // incremental collection set and then start rebuilding it afresh 1357 // after this full GC. 1358 abandon_collection_set(g1_policy()->inc_cset_head()); 1359 g1_policy()->clear_incremental_cset(); 1360 g1_policy()->stop_incremental_cset_building(); 1361 1362 tear_down_region_sets(false /* free_list_only */); 1363 g1_policy()->set_gcs_are_young(true); 1364 1365 // See the comments in g1CollectedHeap.hpp and 1366 // G1CollectedHeap::ref_processing_init() about 1367 // how reference processing currently works in G1. 1368 1369 // Temporarily make discovery by the STW ref processor single threaded (non-MT). 1370 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false); 1371 1372 // Temporarily clear the STW ref processor's _is_alive_non_header field. 1373 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL); 1374 1375 ref_processor_stw()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/); 1376 ref_processor_stw()->setup_policy(do_clear_all_soft_refs); 1377 1378 // Do collection work 1379 { 1380 HandleMark hm; // Discard invalid handles created during gc 1381 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs); 1382 } 1383 1384 assert(free_regions() == 0, "we should not have added any free regions"); 1385 rebuild_region_sets(false /* free_list_only */); 1386 1387 // Enqueue any discovered reference objects that have 1388 // not been removed from the discovered lists. 1389 ref_processor_stw()->enqueue_discovered_references(); 1390 1391 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 1392 1393 MemoryService::track_memory_usage(); 1394 1395 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 1396 ref_processor_stw()->verify_no_references_recorded(); 1397 1398 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 1399 ClassLoaderDataGraph::purge(); 1400 MetaspaceAux::verify_metrics(); 1401 1402 // Note: since we've just done a full GC, concurrent 1403 // marking is no longer active. Therefore we need not 1404 // re-enable reference discovery for the CM ref processor. 1405 // That will be done at the start of the next marking cycle. 1406 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition"); 1407 ref_processor_cm()->verify_no_references_recorded(); 1408 1409 reset_gc_time_stamp(); 1410 // Since everything potentially moved, we will clear all remembered 1411 // sets, and clear all cards. Later we will rebuild remembered 1412 // sets. We will also reset the GC time stamps of the regions. 1413 clear_rsets_post_compaction(); 1414 check_gc_time_stamps(); 1415 1416 // Resize the heap if necessary. 1417 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size); 1418 1419 if (_hr_printer.is_active()) { 1420 // We should do this after we potentially resize the heap so 1421 // that all the COMMIT / UNCOMMIT events are generated before 1422 // the end GC event. 1423 1424 print_hrs_post_compaction(); 1425 _hr_printer.end_gc(true /* full */, (size_t) total_collections()); 1426 } 1427 1428 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 1429 if (hot_card_cache->use_cache()) { 1430 hot_card_cache->reset_card_counts(); 1431 hot_card_cache->reset_hot_cache(); 1432 } 1433 1434 // Rebuild remembered sets of all regions. 1435 if (G1CollectedHeap::use_parallel_gc_threads()) { 1436 uint n_workers = 1437 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 1438 workers()->active_workers(), 1439 Threads::number_of_non_daemon_threads()); 1440 assert(UseDynamicNumberOfGCThreads || 1441 n_workers == workers()->total_workers(), 1442 "If not dynamic should be using all the workers"); 1443 workers()->set_active_workers(n_workers); 1444 // Set parallel threads in the heap (_n_par_threads) only 1445 // before a parallel phase and always reset it to 0 after 1446 // the phase so that the number of parallel threads does 1447 // no get carried forward to a serial phase where there 1448 // may be code that is "possibly_parallel". 1449 set_par_threads(n_workers); 1450 1451 ParRebuildRSTask rebuild_rs_task(this); 1452 assert(check_heap_region_claim_values( 1453 HeapRegion::InitialClaimValue), "sanity check"); 1454 assert(UseDynamicNumberOfGCThreads || 1455 workers()->active_workers() == workers()->total_workers(), 1456 "Unless dynamic should use total workers"); 1457 // Use the most recent number of active workers 1458 assert(workers()->active_workers() > 0, 1459 "Active workers not properly set"); 1460 set_par_threads(workers()->active_workers()); 1461 workers()->run_task(&rebuild_rs_task); 1462 set_par_threads(0); 1463 assert(check_heap_region_claim_values( 1464 HeapRegion::RebuildRSClaimValue), "sanity check"); 1465 reset_heap_region_claim_values(); 1466 } else { 1467 RebuildRSOutOfRegionClosure rebuild_rs(this); 1468 heap_region_iterate(&rebuild_rs); 1469 } 1470 1471 // Rebuild the strong code root lists for each region 1472 rebuild_strong_code_roots(); 1473 1474 if (true) { // FIXME 1475 MetaspaceGC::compute_new_size(); 1476 } 1477 1478 #ifdef TRACESPINNING 1479 ParallelTaskTerminator::print_termination_counts(); 1480 #endif 1481 1482 // Discard all rset updates 1483 JavaThread::dirty_card_queue_set().abandon_logs(); 1484 assert(!G1DeferredRSUpdate 1485 || (G1DeferredRSUpdate && 1486 (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any"); 1487 1488 _young_list->reset_sampled_info(); 1489 // At this point there should be no regions in the 1490 // entire heap tagged as young. 1491 assert(check_young_list_empty(true /* check_heap */), 1492 "young list should be empty at this point"); 1493 1494 // Update the number of full collections that have been completed. 1495 increment_old_marking_cycles_completed(false /* concurrent */); 1496 1497 _hrs.verify_optional(); 1498 verify_region_sets_optional(); 1499 1500 verify_after_gc(); 1501 1502 // Start a new incremental collection set for the next pause 1503 assert(g1_policy()->collection_set() == NULL, "must be"); 1504 g1_policy()->start_incremental_cset_building(); 1505 1506 clear_cset_fast_test(); 1507 1508 init_mutator_alloc_region(); 1509 1510 double end = os::elapsedTime(); 1511 g1_policy()->record_full_collection_end(); 1512 1513 if (G1Log::fine()) { 1514 g1_policy()->print_heap_transition(); 1515 } 1516 1517 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 1518 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 1519 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 1520 // before any GC notifications are raised. 1521 g1mm()->update_sizes(); 1522 1523 gc_epilogue(true); 1524 } 1525 1526 if (G1Log::finer()) { 1527 g1_policy()->print_detailed_heap_transition(true /* full */); 1528 } 1529 1530 print_heap_after_gc(); 1531 trace_heap_after_gc(gc_tracer); 1532 1533 post_full_gc_dump(gc_timer); 1534 1535 gc_timer->register_gc_end(); 1536 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions()); 1537 } 1538 1539 return true; 1540 } 1541 1542 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) { 1543 // do_collection() will return whether it succeeded in performing 1544 // the GC. Currently, there is no facility on the 1545 // do_full_collection() API to notify the caller than the collection 1546 // did not succeed (e.g., because it was locked out by the GC 1547 // locker). So, right now, we'll ignore the return value. 1548 bool dummy = do_collection(true, /* explicit_gc */ 1549 clear_all_soft_refs, 1550 0 /* word_size */); 1551 } 1552 1553 // This code is mostly copied from TenuredGeneration. 1554 void 1555 G1CollectedHeap:: 1556 resize_if_necessary_after_full_collection(size_t word_size) { 1557 // Include the current allocation, if any, and bytes that will be 1558 // pre-allocated to support collections, as "used". 1559 const size_t used_after_gc = used(); 1560 const size_t capacity_after_gc = capacity(); 1561 const size_t free_after_gc = capacity_after_gc - used_after_gc; 1562 1563 // This is enforced in arguments.cpp. 1564 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, 1565 "otherwise the code below doesn't make sense"); 1566 1567 // We don't have floating point command-line arguments 1568 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0; 1569 const double maximum_used_percentage = 1.0 - minimum_free_percentage; 1570 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0; 1571 const double minimum_used_percentage = 1.0 - maximum_free_percentage; 1572 1573 const size_t min_heap_size = collector_policy()->min_heap_byte_size(); 1574 const size_t max_heap_size = collector_policy()->max_heap_byte_size(); 1575 1576 // We have to be careful here as these two calculations can overflow 1577 // 32-bit size_t's. 1578 double used_after_gc_d = (double) used_after_gc; 1579 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage; 1580 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage; 1581 1582 // Let's make sure that they are both under the max heap size, which 1583 // by default will make them fit into a size_t. 1584 double desired_capacity_upper_bound = (double) max_heap_size; 1585 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d, 1586 desired_capacity_upper_bound); 1587 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d, 1588 desired_capacity_upper_bound); 1589 1590 // We can now safely turn them into size_t's. 1591 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d; 1592 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d; 1593 1594 // This assert only makes sense here, before we adjust them 1595 // with respect to the min and max heap size. 1596 assert(minimum_desired_capacity <= maximum_desired_capacity, 1597 err_msg("minimum_desired_capacity = "SIZE_FORMAT", " 1598 "maximum_desired_capacity = "SIZE_FORMAT, 1599 minimum_desired_capacity, maximum_desired_capacity)); 1600 1601 // Should not be greater than the heap max size. No need to adjust 1602 // it with respect to the heap min size as it's a lower bound (i.e., 1603 // we'll try to make the capacity larger than it, not smaller). 1604 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size); 1605 // Should not be less than the heap min size. No need to adjust it 1606 // with respect to the heap max size as it's an upper bound (i.e., 1607 // we'll try to make the capacity smaller than it, not greater). 1608 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size); 1609 1610 if (capacity_after_gc < minimum_desired_capacity) { 1611 // Don't expand unless it's significant 1612 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc; 1613 ergo_verbose4(ErgoHeapSizing, 1614 "attempt heap expansion", 1615 ergo_format_reason("capacity lower than " 1616 "min desired capacity after Full GC") 1617 ergo_format_byte("capacity") 1618 ergo_format_byte("occupancy") 1619 ergo_format_byte_perc("min desired capacity"), 1620 capacity_after_gc, used_after_gc, 1621 minimum_desired_capacity, (double) MinHeapFreeRatio); 1622 expand(expand_bytes); 1623 1624 // No expansion, now see if we want to shrink 1625 } else if (capacity_after_gc > maximum_desired_capacity) { 1626 // Capacity too large, compute shrinking size 1627 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity; 1628 ergo_verbose4(ErgoHeapSizing, 1629 "attempt heap shrinking", 1630 ergo_format_reason("capacity higher than " 1631 "max desired capacity after Full GC") 1632 ergo_format_byte("capacity") 1633 ergo_format_byte("occupancy") 1634 ergo_format_byte_perc("max desired capacity"), 1635 capacity_after_gc, used_after_gc, 1636 maximum_desired_capacity, (double) MaxHeapFreeRatio); 1637 shrink(shrink_bytes); 1638 } 1639 } 1640 1641 1642 HeapWord* 1643 G1CollectedHeap::satisfy_failed_allocation(size_t word_size, 1644 bool* succeeded) { 1645 assert_at_safepoint(true /* should_be_vm_thread */); 1646 1647 *succeeded = true; 1648 // Let's attempt the allocation first. 1649 HeapWord* result = 1650 attempt_allocation_at_safepoint(word_size, 1651 false /* expect_null_mutator_alloc_region */); 1652 if (result != NULL) { 1653 assert(*succeeded, "sanity"); 1654 return result; 1655 } 1656 1657 // In a G1 heap, we're supposed to keep allocation from failing by 1658 // incremental pauses. Therefore, at least for now, we'll favor 1659 // expansion over collection. (This might change in the future if we can 1660 // do something smarter than full collection to satisfy a failed alloc.) 1661 result = expand_and_allocate(word_size); 1662 if (result != NULL) { 1663 assert(*succeeded, "sanity"); 1664 return result; 1665 } 1666 1667 // Expansion didn't work, we'll try to do a Full GC. 1668 bool gc_succeeded = do_collection(false, /* explicit_gc */ 1669 false, /* clear_all_soft_refs */ 1670 word_size); 1671 if (!gc_succeeded) { 1672 *succeeded = false; 1673 return NULL; 1674 } 1675 1676 // Retry the allocation 1677 result = attempt_allocation_at_safepoint(word_size, 1678 true /* expect_null_mutator_alloc_region */); 1679 if (result != NULL) { 1680 assert(*succeeded, "sanity"); 1681 return result; 1682 } 1683 1684 // Then, try a Full GC that will collect all soft references. 1685 gc_succeeded = do_collection(false, /* explicit_gc */ 1686 true, /* clear_all_soft_refs */ 1687 word_size); 1688 if (!gc_succeeded) { 1689 *succeeded = false; 1690 return NULL; 1691 } 1692 1693 // Retry the allocation once more 1694 result = attempt_allocation_at_safepoint(word_size, 1695 true /* expect_null_mutator_alloc_region */); 1696 if (result != NULL) { 1697 assert(*succeeded, "sanity"); 1698 return result; 1699 } 1700 1701 assert(!collector_policy()->should_clear_all_soft_refs(), 1702 "Flag should have been handled and cleared prior to this point"); 1703 1704 // What else? We might try synchronous finalization later. If the total 1705 // space available is large enough for the allocation, then a more 1706 // complete compaction phase than we've tried so far might be 1707 // appropriate. 1708 assert(*succeeded, "sanity"); 1709 return NULL; 1710 } 1711 1712 // Attempting to expand the heap sufficiently 1713 // to support an allocation of the given "word_size". If 1714 // successful, perform the allocation and return the address of the 1715 // allocated block, or else "NULL". 1716 1717 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) { 1718 assert_at_safepoint(true /* should_be_vm_thread */); 1719 1720 verify_region_sets_optional(); 1721 1722 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes); 1723 ergo_verbose1(ErgoHeapSizing, 1724 "attempt heap expansion", 1725 ergo_format_reason("allocation request failed") 1726 ergo_format_byte("allocation request"), 1727 word_size * HeapWordSize); 1728 if (expand(expand_bytes)) { 1729 _hrs.verify_optional(); 1730 verify_region_sets_optional(); 1731 return attempt_allocation_at_safepoint(word_size, 1732 false /* expect_null_mutator_alloc_region */); 1733 } 1734 return NULL; 1735 } 1736 1737 void G1CollectedHeap::update_committed_space(HeapWord* old_end, 1738 HeapWord* new_end) { 1739 assert(old_end != new_end, "don't call this otherwise"); 1740 assert((HeapWord*) _g1_storage.high() == new_end, "invariant"); 1741 1742 // Update the committed mem region. 1743 _g1_committed.set_end(new_end); 1744 // Tell the card table about the update. 1745 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed); 1746 // Tell the BOT about the update. 1747 _bot_shared->resize(_g1_committed.word_size()); 1748 // Tell the hot card cache about the update 1749 _cg1r->hot_card_cache()->resize_card_counts(capacity()); 1750 } 1751 1752 bool G1CollectedHeap::expand(size_t expand_bytes) { 1753 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); 1754 aligned_expand_bytes = align_size_up(aligned_expand_bytes, 1755 HeapRegion::GrainBytes); 1756 ergo_verbose2(ErgoHeapSizing, 1757 "expand the heap", 1758 ergo_format_byte("requested expansion amount") 1759 ergo_format_byte("attempted expansion amount"), 1760 expand_bytes, aligned_expand_bytes); 1761 1762 if (_g1_storage.uncommitted_size() == 0) { 1763 ergo_verbose0(ErgoHeapSizing, 1764 "did not expand the heap", 1765 ergo_format_reason("heap already fully expanded")); 1766 return false; 1767 } 1768 1769 // First commit the memory. 1770 HeapWord* old_end = (HeapWord*) _g1_storage.high(); 1771 bool successful = _g1_storage.expand_by(aligned_expand_bytes); 1772 if (successful) { 1773 // Then propagate this update to the necessary data structures. 1774 HeapWord* new_end = (HeapWord*) _g1_storage.high(); 1775 update_committed_space(old_end, new_end); 1776 1777 FreeRegionList expansion_list("Local Expansion List"); 1778 MemRegion mr = _hrs.expand_by(old_end, new_end, &expansion_list); 1779 assert(mr.start() == old_end, "post-condition"); 1780 // mr might be a smaller region than what was requested if 1781 // expand_by() was unable to allocate the HeapRegion instances 1782 assert(mr.end() <= new_end, "post-condition"); 1783 1784 size_t actual_expand_bytes = mr.byte_size(); 1785 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition"); 1786 assert(actual_expand_bytes == expansion_list.total_capacity_bytes(), 1787 "post-condition"); 1788 if (actual_expand_bytes < aligned_expand_bytes) { 1789 // We could not expand _hrs to the desired size. In this case we 1790 // need to shrink the committed space accordingly. 1791 assert(mr.end() < new_end, "invariant"); 1792 1793 size_t diff_bytes = aligned_expand_bytes - actual_expand_bytes; 1794 // First uncommit the memory. 1795 _g1_storage.shrink_by(diff_bytes); 1796 // Then propagate this update to the necessary data structures. 1797 update_committed_space(new_end, mr.end()); 1798 } 1799 _free_list.add_as_tail(&expansion_list); 1800 1801 if (_hr_printer.is_active()) { 1802 HeapWord* curr = mr.start(); 1803 while (curr < mr.end()) { 1804 HeapWord* curr_end = curr + HeapRegion::GrainWords; 1805 _hr_printer.commit(curr, curr_end); 1806 curr = curr_end; 1807 } 1808 assert(curr == mr.end(), "post-condition"); 1809 } 1810 g1_policy()->record_new_heap_size(n_regions()); 1811 } else { 1812 ergo_verbose0(ErgoHeapSizing, 1813 "did not expand the heap", 1814 ergo_format_reason("heap expansion operation failed")); 1815 // The expansion of the virtual storage space was unsuccessful. 1816 // Let's see if it was because we ran out of swap. 1817 if (G1ExitOnExpansionFailure && 1818 _g1_storage.uncommitted_size() >= aligned_expand_bytes) { 1819 // We had head room... 1820 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion"); 1821 } 1822 } 1823 return successful; 1824 } 1825 1826 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) { 1827 size_t aligned_shrink_bytes = 1828 ReservedSpace::page_align_size_down(shrink_bytes); 1829 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes, 1830 HeapRegion::GrainBytes); 1831 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes); 1832 1833 uint num_regions_removed = _hrs.shrink_by(num_regions_to_remove); 1834 HeapWord* old_end = (HeapWord*) _g1_storage.high(); 1835 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes; 1836 1837 ergo_verbose3(ErgoHeapSizing, 1838 "shrink the heap", 1839 ergo_format_byte("requested shrinking amount") 1840 ergo_format_byte("aligned shrinking amount") 1841 ergo_format_byte("attempted shrinking amount"), 1842 shrink_bytes, aligned_shrink_bytes, shrunk_bytes); 1843 if (num_regions_removed > 0) { 1844 _g1_storage.shrink_by(shrunk_bytes); 1845 HeapWord* new_end = (HeapWord*) _g1_storage.high(); 1846 1847 if (_hr_printer.is_active()) { 1848 HeapWord* curr = old_end; 1849 while (curr > new_end) { 1850 HeapWord* curr_end = curr; 1851 curr -= HeapRegion::GrainWords; 1852 _hr_printer.uncommit(curr, curr_end); 1853 } 1854 } 1855 1856 _expansion_regions += num_regions_removed; 1857 update_committed_space(old_end, new_end); 1858 HeapRegionRemSet::shrink_heap(n_regions()); 1859 g1_policy()->record_new_heap_size(n_regions()); 1860 } else { 1861 ergo_verbose0(ErgoHeapSizing, 1862 "did not shrink the heap", 1863 ergo_format_reason("heap shrinking operation failed")); 1864 } 1865 } 1866 1867 void G1CollectedHeap::shrink(size_t shrink_bytes) { 1868 verify_region_sets_optional(); 1869 1870 // We should only reach here at the end of a Full GC which means we 1871 // should not not be holding to any GC alloc regions. The method 1872 // below will make sure of that and do any remaining clean up. 1873 abandon_gc_alloc_regions(); 1874 1875 // Instead of tearing down / rebuilding the free lists here, we 1876 // could instead use the remove_all_pending() method on free_list to 1877 // remove only the ones that we need to remove. 1878 tear_down_region_sets(true /* free_list_only */); 1879 shrink_helper(shrink_bytes); 1880 rebuild_region_sets(true /* free_list_only */); 1881 1882 _hrs.verify_optional(); 1883 verify_region_sets_optional(); 1884 } 1885 1886 // Public methods. 1887 1888 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away 1889 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list 1890 #endif // _MSC_VER 1891 1892 1893 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) : 1894 SharedHeap(policy_), 1895 _g1_policy(policy_), 1896 _dirty_card_queue_set(false), 1897 _into_cset_dirty_card_queue_set(false), 1898 _is_alive_closure_cm(this), 1899 _is_alive_closure_stw(this), 1900 _ref_processor_cm(NULL), 1901 _ref_processor_stw(NULL), 1902 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)), 1903 _bot_shared(NULL), 1904 _evac_failure_scan_stack(NULL), 1905 _mark_in_progress(false), 1906 _cg1r(NULL), _summary_bytes_used(0), 1907 _g1mm(NULL), 1908 _refine_cte_cl(NULL), 1909 _full_collection(false), 1910 _free_list("Master Free List", new MasterFreeRegionListMtSafeChecker()), 1911 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()), 1912 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()), 1913 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()), 1914 _free_regions_coming(false), 1915 _young_list(new YoungList(this)), 1916 _gc_time_stamp(0), 1917 _retained_old_gc_alloc_region(NULL), 1918 _survivor_plab_stats(YoungPLABSize, PLABWeight), 1919 _old_plab_stats(OldPLABSize, PLABWeight), 1920 _expand_heap_after_alloc_failure(true), 1921 _surviving_young_words(NULL), 1922 _old_marking_cycles_started(0), 1923 _old_marking_cycles_completed(0), 1924 _concurrent_cycle_started(false), 1925 _in_cset_fast_test(), 1926 _dirty_cards_region_list(NULL), 1927 _worker_cset_start_region(NULL), 1928 _worker_cset_start_region_time_stamp(NULL), 1929 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()), 1930 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()), 1931 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()), 1932 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) { 1933 1934 _g1h = this; 1935 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) { 1936 vm_exit_during_initialization("Failed necessary allocation."); 1937 } 1938 1939 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2; 1940 1941 int n_queues = MAX2((int)ParallelGCThreads, 1); 1942 _task_queues = new RefToScanQueueSet(n_queues); 1943 1944 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets(); 1945 assert(n_rem_sets > 0, "Invariant."); 1946 1947 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC); 1948 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(unsigned int, n_queues, mtGC); 1949 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC); 1950 1951 for (int i = 0; i < n_queues; i++) { 1952 RefToScanQueue* q = new RefToScanQueue(); 1953 q->initialize(); 1954 _task_queues->register_queue(i, q); 1955 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo(); 1956 } 1957 clear_cset_start_regions(); 1958 1959 // Initialize the G1EvacuationFailureALot counters and flags. 1960 NOT_PRODUCT(reset_evacuation_should_fail();) 1961 1962 guarantee(_task_queues != NULL, "task_queues allocation failure."); 1963 } 1964 1965 jint G1CollectedHeap::initialize() { 1966 CollectedHeap::pre_initialize(); 1967 os::enable_vtime(); 1968 1969 G1Log::init(); 1970 1971 // Necessary to satisfy locking discipline assertions. 1972 1973 MutexLocker x(Heap_lock); 1974 1975 // We have to initialize the printer before committing the heap, as 1976 // it will be used then. 1977 _hr_printer.set_active(G1PrintHeapRegions); 1978 1979 // While there are no constraints in the GC code that HeapWordSize 1980 // be any particular value, there are multiple other areas in the 1981 // system which believe this to be true (e.g. oop->object_size in some 1982 // cases incorrectly returns the size in wordSize units rather than 1983 // HeapWordSize). 1984 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 1985 1986 size_t init_byte_size = collector_policy()->initial_heap_byte_size(); 1987 size_t max_byte_size = collector_policy()->max_heap_byte_size(); 1988 size_t heap_alignment = collector_policy()->heap_alignment(); 1989 1990 // Ensure that the sizes are properly aligned. 1991 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1992 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1993 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap"); 1994 1995 _refine_cte_cl = new RefineCardTableEntryClosure(); 1996 1997 _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl); 1998 1999 // Reserve the maximum. 2000 2001 // When compressed oops are enabled, the preferred heap base 2002 // is calculated by subtracting the requested size from the 2003 // 32Gb boundary and using the result as the base address for 2004 // heap reservation. If the requested size is not aligned to 2005 // HeapRegion::GrainBytes (i.e. the alignment that is passed 2006 // into the ReservedHeapSpace constructor) then the actual 2007 // base of the reserved heap may end up differing from the 2008 // address that was requested (i.e. the preferred heap base). 2009 // If this happens then we could end up using a non-optimal 2010 // compressed oops mode. 2011 2012 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size, 2013 heap_alignment); 2014 2015 // It is important to do this in a way such that concurrent readers can't 2016 // temporarily think something is in the heap. (I've actually seen this 2017 // happen in asserts: DLD.) 2018 _reserved.set_word_size(0); 2019 _reserved.set_start((HeapWord*)heap_rs.base()); 2020 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size())); 2021 2022 _expansion_regions = (uint) (max_byte_size / HeapRegion::GrainBytes); 2023 2024 // Create the gen rem set (and barrier set) for the entire reserved region. 2025 _rem_set = collector_policy()->create_rem_set(_reserved, 2); 2026 set_barrier_set(rem_set()->bs()); 2027 if (!barrier_set()->is_a(BarrierSet::G1SATBCTLogging)) { 2028 vm_exit_during_initialization("G1 requires a G1SATBLoggingCardTableModRefBS"); 2029 return JNI_ENOMEM; 2030 } 2031 2032 // Also create a G1 rem set. 2033 _g1_rem_set = new G1RemSet(this, g1_barrier_set()); 2034 2035 // Carve out the G1 part of the heap. 2036 2037 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size); 2038 _g1_reserved = MemRegion((HeapWord*)g1_rs.base(), 2039 g1_rs.size()/HeapWordSize); 2040 2041 _g1_storage.initialize(g1_rs, 0); 2042 _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0); 2043 _hrs.initialize((HeapWord*) _g1_reserved.start(), 2044 (HeapWord*) _g1_reserved.end()); 2045 assert(_hrs.max_length() == _expansion_regions, 2046 err_msg("max length: %u expansion regions: %u", 2047 _hrs.max_length(), _expansion_regions)); 2048 2049 // Do later initialization work for concurrent refinement. 2050 _cg1r->init(); 2051 2052 // 6843694 - ensure that the maximum region index can fit 2053 // in the remembered set structures. 2054 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; 2055 guarantee((max_regions() - 1) <= max_region_idx, "too many regions"); 2056 2057 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; 2058 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); 2059 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region, 2060 "too many cards per region"); 2061 2062 FreeRegionList::set_unrealistically_long_length(max_regions() + 1); 2063 2064 _bot_shared = new G1BlockOffsetSharedArray(_reserved, 2065 heap_word_size(init_byte_size)); 2066 2067 _g1h = this; 2068 2069 _in_cset_fast_test.initialize(_g1_reserved.start(), _g1_reserved.end(), HeapRegion::GrainBytes); 2070 2071 // Create the ConcurrentMark data structure and thread. 2072 // (Must do this late, so that "max_regions" is defined.) 2073 _cm = new ConcurrentMark(this, heap_rs); 2074 if (_cm == NULL || !_cm->completed_initialization()) { 2075 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark"); 2076 return JNI_ENOMEM; 2077 } 2078 _cmThread = _cm->cmThread(); 2079 2080 // Initialize the from_card cache structure of HeapRegionRemSet. 2081 HeapRegionRemSet::init_heap(max_regions()); 2082 2083 // Now expand into the initial heap size. 2084 if (!expand(init_byte_size)) { 2085 vm_shutdown_during_initialization("Failed to allocate initial heap."); 2086 return JNI_ENOMEM; 2087 } 2088 2089 // Perform any initialization actions delegated to the policy. 2090 g1_policy()->init(); 2091 2092 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon, 2093 SATB_Q_FL_lock, 2094 G1SATBProcessCompletedThreshold, 2095 Shared_SATB_Q_lock); 2096 2097 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl, 2098 DirtyCardQ_CBL_mon, 2099 DirtyCardQ_FL_lock, 2100 concurrent_g1_refine()->yellow_zone(), 2101 concurrent_g1_refine()->red_zone(), 2102 Shared_DirtyCardQ_lock); 2103 2104 if (G1DeferredRSUpdate) { 2105 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code 2106 DirtyCardQ_CBL_mon, 2107 DirtyCardQ_FL_lock, 2108 -1, // never trigger processing 2109 -1, // no limit on length 2110 Shared_DirtyCardQ_lock, 2111 &JavaThread::dirty_card_queue_set()); 2112 } 2113 2114 // Initialize the card queue set used to hold cards containing 2115 // references into the collection set. 2116 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code 2117 DirtyCardQ_CBL_mon, 2118 DirtyCardQ_FL_lock, 2119 -1, // never trigger processing 2120 -1, // no limit on length 2121 Shared_DirtyCardQ_lock, 2122 &JavaThread::dirty_card_queue_set()); 2123 2124 // In case we're keeping closure specialization stats, initialize those 2125 // counts and that mechanism. 2126 SpecializationStats::clear(); 2127 2128 // Here we allocate the dummy full region that is required by the 2129 // G1AllocRegion class. If we don't pass an address in the reserved 2130 // space here, lots of asserts fire. 2131 2132 HeapRegion* dummy_region = new_heap_region(0 /* index of bottom region */, 2133 _g1_reserved.start()); 2134 // We'll re-use the same region whether the alloc region will 2135 // require BOT updates or not and, if it doesn't, then a non-young 2136 // region will complain that it cannot support allocations without 2137 // BOT updates. So we'll tag the dummy region as young to avoid that. 2138 dummy_region->set_young(); 2139 // Make sure it's full. 2140 dummy_region->set_top(dummy_region->end()); 2141 G1AllocRegion::setup(this, dummy_region); 2142 2143 init_mutator_alloc_region(); 2144 2145 // Do create of the monitoring and management support so that 2146 // values in the heap have been properly initialized. 2147 _g1mm = new G1MonitoringSupport(this); 2148 2149 G1StringDedup::initialize(); 2150 2151 return JNI_OK; 2152 } 2153 2154 void G1CollectedHeap::stop() { 2155 #if 0 2156 // Stopping concurrent worker threads is currently disabled until 2157 // some bugs in concurrent mark has been resolve. Without fixing 2158 // those bugs first we risk haning during VM exit when trying to 2159 // stop these threads. 2160 2161 // Abort any ongoing concurrent root region scanning and stop all 2162 // concurrent threads. We do this to make sure these threads do 2163 // not continue to execute and access resources (e.g. gclog_or_tty) 2164 // that are destroyed during shutdown. 2165 _cm->root_regions()->abort(); 2166 _cm->root_regions()->wait_until_scan_finished(); 2167 stop_conc_gc_threads(); 2168 #endif 2169 } 2170 2171 size_t G1CollectedHeap::conservative_max_heap_alignment() { 2172 return HeapRegion::max_region_size(); 2173 } 2174 2175 void G1CollectedHeap::ref_processing_init() { 2176 // Reference processing in G1 currently works as follows: 2177 // 2178 // * There are two reference processor instances. One is 2179 // used to record and process discovered references 2180 // during concurrent marking; the other is used to 2181 // record and process references during STW pauses 2182 // (both full and incremental). 2183 // * Both ref processors need to 'span' the entire heap as 2184 // the regions in the collection set may be dotted around. 2185 // 2186 // * For the concurrent marking ref processor: 2187 // * Reference discovery is enabled at initial marking. 2188 // * Reference discovery is disabled and the discovered 2189 // references processed etc during remarking. 2190 // * Reference discovery is MT (see below). 2191 // * Reference discovery requires a barrier (see below). 2192 // * Reference processing may or may not be MT 2193 // (depending on the value of ParallelRefProcEnabled 2194 // and ParallelGCThreads). 2195 // * A full GC disables reference discovery by the CM 2196 // ref processor and abandons any entries on it's 2197 // discovered lists. 2198 // 2199 // * For the STW processor: 2200 // * Non MT discovery is enabled at the start of a full GC. 2201 // * Processing and enqueueing during a full GC is non-MT. 2202 // * During a full GC, references are processed after marking. 2203 // 2204 // * Discovery (may or may not be MT) is enabled at the start 2205 // of an incremental evacuation pause. 2206 // * References are processed near the end of a STW evacuation pause. 2207 // * For both types of GC: 2208 // * Discovery is atomic - i.e. not concurrent. 2209 // * Reference discovery will not need a barrier. 2210 2211 SharedHeap::ref_processing_init(); 2212 MemRegion mr = reserved_region(); 2213 2214 // Concurrent Mark ref processor 2215 _ref_processor_cm = 2216 new ReferenceProcessor(mr, // span 2217 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2218 // mt processing 2219 (int) ParallelGCThreads, 2220 // degree of mt processing 2221 (ParallelGCThreads > 1) || (ConcGCThreads > 1), 2222 // mt discovery 2223 (int) MAX2(ParallelGCThreads, ConcGCThreads), 2224 // degree of mt discovery 2225 false, 2226 // Reference discovery is not atomic 2227 &_is_alive_closure_cm, 2228 // is alive closure 2229 // (for efficiency/performance) 2230 true); 2231 // Setting next fields of discovered 2232 // lists requires a barrier. 2233 2234 // STW ref processor 2235 _ref_processor_stw = 2236 new ReferenceProcessor(mr, // span 2237 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2238 // mt processing 2239 MAX2((int)ParallelGCThreads, 1), 2240 // degree of mt processing 2241 (ParallelGCThreads > 1), 2242 // mt discovery 2243 MAX2((int)ParallelGCThreads, 1), 2244 // degree of mt discovery 2245 true, 2246 // Reference discovery is atomic 2247 &_is_alive_closure_stw, 2248 // is alive closure 2249 // (for efficiency/performance) 2250 false); 2251 // Setting next fields of discovered 2252 // lists does not require a barrier. 2253 } 2254 2255 size_t G1CollectedHeap::capacity() const { 2256 return _g1_committed.byte_size(); 2257 } 2258 2259 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) { 2260 assert(!hr->continuesHumongous(), "pre-condition"); 2261 hr->reset_gc_time_stamp(); 2262 if (hr->startsHumongous()) { 2263 uint first_index = hr->hrs_index() + 1; 2264 uint last_index = hr->last_hc_index(); 2265 for (uint i = first_index; i < last_index; i += 1) { 2266 HeapRegion* chr = region_at(i); 2267 assert(chr->continuesHumongous(), "sanity"); 2268 chr->reset_gc_time_stamp(); 2269 } 2270 } 2271 } 2272 2273 #ifndef PRODUCT 2274 class CheckGCTimeStampsHRClosure : public HeapRegionClosure { 2275 private: 2276 unsigned _gc_time_stamp; 2277 bool _failures; 2278 2279 public: 2280 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) : 2281 _gc_time_stamp(gc_time_stamp), _failures(false) { } 2282 2283 virtual bool doHeapRegion(HeapRegion* hr) { 2284 unsigned region_gc_time_stamp = hr->get_gc_time_stamp(); 2285 if (_gc_time_stamp != region_gc_time_stamp) { 2286 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, " 2287 "expected %d", HR_FORMAT_PARAMS(hr), 2288 region_gc_time_stamp, _gc_time_stamp); 2289 _failures = true; 2290 } 2291 return false; 2292 } 2293 2294 bool failures() { return _failures; } 2295 }; 2296 2297 void G1CollectedHeap::check_gc_time_stamps() { 2298 CheckGCTimeStampsHRClosure cl(_gc_time_stamp); 2299 heap_region_iterate(&cl); 2300 guarantee(!cl.failures(), "all GC time stamps should have been reset"); 2301 } 2302 #endif // PRODUCT 2303 2304 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, 2305 DirtyCardQueue* into_cset_dcq, 2306 bool concurrent, 2307 uint worker_i) { 2308 // Clean cards in the hot card cache 2309 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 2310 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq); 2311 2312 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 2313 int n_completed_buffers = 0; 2314 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) { 2315 n_completed_buffers++; 2316 } 2317 g1_policy()->phase_times()->record_update_rs_processed_buffers(worker_i, n_completed_buffers); 2318 dcqs.clear_n_completed_buffers(); 2319 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!"); 2320 } 2321 2322 2323 // Computes the sum of the storage used by the various regions. 2324 2325 size_t G1CollectedHeap::used() const { 2326 assert(Heap_lock->owner() != NULL, 2327 "Should be owned on this thread's behalf."); 2328 size_t result = _summary_bytes_used; 2329 // Read only once in case it is set to NULL concurrently 2330 HeapRegion* hr = _mutator_alloc_region.get(); 2331 if (hr != NULL) 2332 result += hr->used(); 2333 return result; 2334 } 2335 2336 size_t G1CollectedHeap::used_unlocked() const { 2337 size_t result = _summary_bytes_used; 2338 return result; 2339 } 2340 2341 class SumUsedClosure: public HeapRegionClosure { 2342 size_t _used; 2343 public: 2344 SumUsedClosure() : _used(0) {} 2345 bool doHeapRegion(HeapRegion* r) { 2346 if (!r->continuesHumongous()) { 2347 _used += r->used(); 2348 } 2349 return false; 2350 } 2351 size_t result() { return _used; } 2352 }; 2353 2354 size_t G1CollectedHeap::recalculate_used() const { 2355 double recalculate_used_start = os::elapsedTime(); 2356 2357 SumUsedClosure blk; 2358 heap_region_iterate(&blk); 2359 2360 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0); 2361 return blk.result(); 2362 } 2363 2364 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 2365 switch (cause) { 2366 case GCCause::_gc_locker: return GCLockerInvokesConcurrent; 2367 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent; 2368 case GCCause::_g1_humongous_allocation: return true; 2369 default: return false; 2370 } 2371 } 2372 2373 #ifndef PRODUCT 2374 void G1CollectedHeap::allocate_dummy_regions() { 2375 // Let's fill up most of the region 2376 size_t word_size = HeapRegion::GrainWords - 1024; 2377 // And as a result the region we'll allocate will be humongous. 2378 guarantee(isHumongous(word_size), "sanity"); 2379 2380 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) { 2381 // Let's use the existing mechanism for the allocation 2382 HeapWord* dummy_obj = humongous_obj_allocate(word_size); 2383 if (dummy_obj != NULL) { 2384 MemRegion mr(dummy_obj, word_size); 2385 CollectedHeap::fill_with_object(mr); 2386 } else { 2387 // If we can't allocate once, we probably cannot allocate 2388 // again. Let's get out of the loop. 2389 break; 2390 } 2391 } 2392 } 2393 #endif // !PRODUCT 2394 2395 void G1CollectedHeap::increment_old_marking_cycles_started() { 2396 assert(_old_marking_cycles_started == _old_marking_cycles_completed || 2397 _old_marking_cycles_started == _old_marking_cycles_completed + 1, 2398 err_msg("Wrong marking cycle count (started: %d, completed: %d)", 2399 _old_marking_cycles_started, _old_marking_cycles_completed)); 2400 2401 _old_marking_cycles_started++; 2402 } 2403 2404 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) { 2405 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 2406 2407 // We assume that if concurrent == true, then the caller is a 2408 // concurrent thread that was joined the Suspendible Thread 2409 // Set. If there's ever a cheap way to check this, we should add an 2410 // assert here. 2411 2412 // Given that this method is called at the end of a Full GC or of a 2413 // concurrent cycle, and those can be nested (i.e., a Full GC can 2414 // interrupt a concurrent cycle), the number of full collections 2415 // completed should be either one (in the case where there was no 2416 // nesting) or two (when a Full GC interrupted a concurrent cycle) 2417 // behind the number of full collections started. 2418 2419 // This is the case for the inner caller, i.e. a Full GC. 2420 assert(concurrent || 2421 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || 2422 (_old_marking_cycles_started == _old_marking_cycles_completed + 2), 2423 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u " 2424 "is inconsistent with _old_marking_cycles_completed = %u", 2425 _old_marking_cycles_started, _old_marking_cycles_completed)); 2426 2427 // This is the case for the outer caller, i.e. the concurrent cycle. 2428 assert(!concurrent || 2429 (_old_marking_cycles_started == _old_marking_cycles_completed + 1), 2430 err_msg("for outer caller (concurrent cycle): " 2431 "_old_marking_cycles_started = %u " 2432 "is inconsistent with _old_marking_cycles_completed = %u", 2433 _old_marking_cycles_started, _old_marking_cycles_completed)); 2434 2435 _old_marking_cycles_completed += 1; 2436 2437 // We need to clear the "in_progress" flag in the CM thread before 2438 // we wake up any waiters (especially when ExplicitInvokesConcurrent 2439 // is set) so that if a waiter requests another System.gc() it doesn't 2440 // incorrectly see that a marking cycle is still in progress. 2441 if (concurrent) { 2442 _cmThread->clear_in_progress(); 2443 } 2444 2445 // This notify_all() will ensure that a thread that called 2446 // System.gc() with (with ExplicitGCInvokesConcurrent set or not) 2447 // and it's waiting for a full GC to finish will be woken up. It is 2448 // waiting in VM_G1IncCollectionPause::doit_epilogue(). 2449 FullGCCount_lock->notify_all(); 2450 } 2451 2452 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) { 2453 _concurrent_cycle_started = true; 2454 _gc_timer_cm->register_gc_start(start_time); 2455 2456 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start()); 2457 trace_heap_before_gc(_gc_tracer_cm); 2458 } 2459 2460 void G1CollectedHeap::register_concurrent_cycle_end() { 2461 if (_concurrent_cycle_started) { 2462 if (_cm->has_aborted()) { 2463 _gc_tracer_cm->report_concurrent_mode_failure(); 2464 } 2465 2466 _gc_timer_cm->register_gc_end(); 2467 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions()); 2468 2469 _concurrent_cycle_started = false; 2470 } 2471 } 2472 2473 void G1CollectedHeap::trace_heap_after_concurrent_cycle() { 2474 if (_concurrent_cycle_started) { 2475 trace_heap_after_gc(_gc_tracer_cm); 2476 } 2477 } 2478 2479 G1YCType G1CollectedHeap::yc_type() { 2480 bool is_young = g1_policy()->gcs_are_young(); 2481 bool is_initial_mark = g1_policy()->during_initial_mark_pause(); 2482 bool is_during_mark = mark_in_progress(); 2483 2484 if (is_initial_mark) { 2485 return InitialMark; 2486 } else if (is_during_mark) { 2487 return DuringMark; 2488 } else if (is_young) { 2489 return Normal; 2490 } else { 2491 return Mixed; 2492 } 2493 } 2494 2495 void G1CollectedHeap::collect(GCCause::Cause cause) { 2496 assert_heap_not_locked(); 2497 2498 unsigned int gc_count_before; 2499 unsigned int old_marking_count_before; 2500 bool retry_gc; 2501 2502 do { 2503 retry_gc = false; 2504 2505 { 2506 MutexLocker ml(Heap_lock); 2507 2508 // Read the GC count while holding the Heap_lock 2509 gc_count_before = total_collections(); 2510 old_marking_count_before = _old_marking_cycles_started; 2511 } 2512 2513 if (should_do_concurrent_full_gc(cause)) { 2514 // Schedule an initial-mark evacuation pause that will start a 2515 // concurrent cycle. We're setting word_size to 0 which means that 2516 // we are not requesting a post-GC allocation. 2517 VM_G1IncCollectionPause op(gc_count_before, 2518 0, /* word_size */ 2519 true, /* should_initiate_conc_mark */ 2520 g1_policy()->max_pause_time_ms(), 2521 cause); 2522 2523 VMThread::execute(&op); 2524 if (!op.pause_succeeded()) { 2525 if (old_marking_count_before == _old_marking_cycles_started) { 2526 retry_gc = op.should_retry_gc(); 2527 } else { 2528 // A Full GC happened while we were trying to schedule the 2529 // initial-mark GC. No point in starting a new cycle given 2530 // that the whole heap was collected anyway. 2531 } 2532 2533 if (retry_gc) { 2534 if (GC_locker::is_active_and_needs_gc()) { 2535 GC_locker::stall_until_clear(); 2536 } 2537 } 2538 } 2539 } else { 2540 if (cause == GCCause::_gc_locker 2541 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { 2542 2543 // Schedule a standard evacuation pause. We're setting word_size 2544 // to 0 which means that we are not requesting a post-GC allocation. 2545 VM_G1IncCollectionPause op(gc_count_before, 2546 0, /* word_size */ 2547 false, /* should_initiate_conc_mark */ 2548 g1_policy()->max_pause_time_ms(), 2549 cause); 2550 VMThread::execute(&op); 2551 } else { 2552 // Schedule a Full GC. 2553 VM_G1CollectFull op(gc_count_before, old_marking_count_before, cause); 2554 VMThread::execute(&op); 2555 } 2556 } 2557 } while (retry_gc); 2558 } 2559 2560 bool G1CollectedHeap::is_in(const void* p) const { 2561 if (_g1_committed.contains(p)) { 2562 // Given that we know that p is in the committed space, 2563 // heap_region_containing_raw() should successfully 2564 // return the containing region. 2565 HeapRegion* hr = heap_region_containing_raw(p); 2566 return hr->is_in(p); 2567 } else { 2568 return false; 2569 } 2570 } 2571 2572 // Iteration functions. 2573 2574 // Iterates an OopClosure over all ref-containing fields of objects 2575 // within a HeapRegion. 2576 2577 class IterateOopClosureRegionClosure: public HeapRegionClosure { 2578 MemRegion _mr; 2579 ExtendedOopClosure* _cl; 2580 public: 2581 IterateOopClosureRegionClosure(MemRegion mr, ExtendedOopClosure* cl) 2582 : _mr(mr), _cl(cl) {} 2583 bool doHeapRegion(HeapRegion* r) { 2584 if (!r->continuesHumongous()) { 2585 r->oop_iterate(_cl); 2586 } 2587 return false; 2588 } 2589 }; 2590 2591 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) { 2592 IterateOopClosureRegionClosure blk(_g1_committed, cl); 2593 heap_region_iterate(&blk); 2594 } 2595 2596 void G1CollectedHeap::oop_iterate(MemRegion mr, ExtendedOopClosure* cl) { 2597 IterateOopClosureRegionClosure blk(mr, cl); 2598 heap_region_iterate(&blk); 2599 } 2600 2601 // Iterates an ObjectClosure over all objects within a HeapRegion. 2602 2603 class IterateObjectClosureRegionClosure: public HeapRegionClosure { 2604 ObjectClosure* _cl; 2605 public: 2606 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} 2607 bool doHeapRegion(HeapRegion* r) { 2608 if (! r->continuesHumongous()) { 2609 r->object_iterate(_cl); 2610 } 2611 return false; 2612 } 2613 }; 2614 2615 void G1CollectedHeap::object_iterate(ObjectClosure* cl) { 2616 IterateObjectClosureRegionClosure blk(cl); 2617 heap_region_iterate(&blk); 2618 } 2619 2620 // Calls a SpaceClosure on a HeapRegion. 2621 2622 class SpaceClosureRegionClosure: public HeapRegionClosure { 2623 SpaceClosure* _cl; 2624 public: 2625 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {} 2626 bool doHeapRegion(HeapRegion* r) { 2627 _cl->do_space(r); 2628 return false; 2629 } 2630 }; 2631 2632 void G1CollectedHeap::space_iterate(SpaceClosure* cl) { 2633 SpaceClosureRegionClosure blk(cl); 2634 heap_region_iterate(&blk); 2635 } 2636 2637 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { 2638 _hrs.iterate(cl); 2639 } 2640 2641 void 2642 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl, 2643 uint worker_id, 2644 uint no_of_par_workers, 2645 jint claim_value) { 2646 const uint regions = n_regions(); 2647 const uint max_workers = (G1CollectedHeap::use_parallel_gc_threads() ? 2648 no_of_par_workers : 2649 1); 2650 assert(UseDynamicNumberOfGCThreads || 2651 no_of_par_workers == workers()->total_workers(), 2652 "Non dynamic should use fixed number of workers"); 2653 // try to spread out the starting points of the workers 2654 const HeapRegion* start_hr = 2655 start_region_for_worker(worker_id, no_of_par_workers); 2656 const uint start_index = start_hr->hrs_index(); 2657 2658 // each worker will actually look at all regions 2659 for (uint count = 0; count < regions; ++count) { 2660 const uint index = (start_index + count) % regions; 2661 assert(0 <= index && index < regions, "sanity"); 2662 HeapRegion* r = region_at(index); 2663 // we'll ignore "continues humongous" regions (we'll process them 2664 // when we come across their corresponding "start humongous" 2665 // region) and regions already claimed 2666 if (r->claim_value() == claim_value || r->continuesHumongous()) { 2667 continue; 2668 } 2669 // OK, try to claim it 2670 if (r->claimHeapRegion(claim_value)) { 2671 // success! 2672 assert(!r->continuesHumongous(), "sanity"); 2673 if (r->startsHumongous()) { 2674 // If the region is "starts humongous" we'll iterate over its 2675 // "continues humongous" first; in fact we'll do them 2676 // first. The order is important. In on case, calling the 2677 // closure on the "starts humongous" region might de-allocate 2678 // and clear all its "continues humongous" regions and, as a 2679 // result, we might end up processing them twice. So, we'll do 2680 // them first (notice: most closures will ignore them anyway) and 2681 // then we'll do the "starts humongous" region. 2682 for (uint ch_index = index + 1; ch_index < regions; ++ch_index) { 2683 HeapRegion* chr = region_at(ch_index); 2684 2685 // if the region has already been claimed or it's not 2686 // "continues humongous" we're done 2687 if (chr->claim_value() == claim_value || 2688 !chr->continuesHumongous()) { 2689 break; 2690 } 2691 2692 // No one should have claimed it directly. We can given 2693 // that we claimed its "starts humongous" region. 2694 assert(chr->claim_value() != claim_value, "sanity"); 2695 assert(chr->humongous_start_region() == r, "sanity"); 2696 2697 if (chr->claimHeapRegion(claim_value)) { 2698 // we should always be able to claim it; no one else should 2699 // be trying to claim this region 2700 2701 bool res2 = cl->doHeapRegion(chr); 2702 assert(!res2, "Should not abort"); 2703 2704 // Right now, this holds (i.e., no closure that actually 2705 // does something with "continues humongous" regions 2706 // clears them). We might have to weaken it in the future, 2707 // but let's leave these two asserts here for extra safety. 2708 assert(chr->continuesHumongous(), "should still be the case"); 2709 assert(chr->humongous_start_region() == r, "sanity"); 2710 } else { 2711 guarantee(false, "we should not reach here"); 2712 } 2713 } 2714 } 2715 2716 assert(!r->continuesHumongous(), "sanity"); 2717 bool res = cl->doHeapRegion(r); 2718 assert(!res, "Should not abort"); 2719 } 2720 } 2721 } 2722 2723 class ResetClaimValuesClosure: public HeapRegionClosure { 2724 public: 2725 bool doHeapRegion(HeapRegion* r) { 2726 r->set_claim_value(HeapRegion::InitialClaimValue); 2727 return false; 2728 } 2729 }; 2730 2731 void G1CollectedHeap::reset_heap_region_claim_values() { 2732 ResetClaimValuesClosure blk; 2733 heap_region_iterate(&blk); 2734 } 2735 2736 void G1CollectedHeap::reset_cset_heap_region_claim_values() { 2737 ResetClaimValuesClosure blk; 2738 collection_set_iterate(&blk); 2739 } 2740 2741 #ifdef ASSERT 2742 // This checks whether all regions in the heap have the correct claim 2743 // value. I also piggy-backed on this a check to ensure that the 2744 // humongous_start_region() information on "continues humongous" 2745 // regions is correct. 2746 2747 class CheckClaimValuesClosure : public HeapRegionClosure { 2748 private: 2749 jint _claim_value; 2750 uint _failures; 2751 HeapRegion* _sh_region; 2752 2753 public: 2754 CheckClaimValuesClosure(jint claim_value) : 2755 _claim_value(claim_value), _failures(0), _sh_region(NULL) { } 2756 bool doHeapRegion(HeapRegion* r) { 2757 if (r->claim_value() != _claim_value) { 2758 gclog_or_tty->print_cr("Region " HR_FORMAT ", " 2759 "claim value = %d, should be %d", 2760 HR_FORMAT_PARAMS(r), 2761 r->claim_value(), _claim_value); 2762 ++_failures; 2763 } 2764 if (!r->isHumongous()) { 2765 _sh_region = NULL; 2766 } else if (r->startsHumongous()) { 2767 _sh_region = r; 2768 } else if (r->continuesHumongous()) { 2769 if (r->humongous_start_region() != _sh_region) { 2770 gclog_or_tty->print_cr("Region " HR_FORMAT ", " 2771 "HS = "PTR_FORMAT", should be "PTR_FORMAT, 2772 HR_FORMAT_PARAMS(r), 2773 r->humongous_start_region(), 2774 _sh_region); 2775 ++_failures; 2776 } 2777 } 2778 return false; 2779 } 2780 uint failures() { return _failures; } 2781 }; 2782 2783 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) { 2784 CheckClaimValuesClosure cl(claim_value); 2785 heap_region_iterate(&cl); 2786 return cl.failures() == 0; 2787 } 2788 2789 class CheckClaimValuesInCSetHRClosure: public HeapRegionClosure { 2790 private: 2791 jint _claim_value; 2792 uint _failures; 2793 2794 public: 2795 CheckClaimValuesInCSetHRClosure(jint claim_value) : 2796 _claim_value(claim_value), _failures(0) { } 2797 2798 uint failures() { return _failures; } 2799 2800 bool doHeapRegion(HeapRegion* hr) { 2801 assert(hr->in_collection_set(), "how?"); 2802 assert(!hr->isHumongous(), "H-region in CSet"); 2803 if (hr->claim_value() != _claim_value) { 2804 gclog_or_tty->print_cr("CSet Region " HR_FORMAT ", " 2805 "claim value = %d, should be %d", 2806 HR_FORMAT_PARAMS(hr), 2807 hr->claim_value(), _claim_value); 2808 _failures += 1; 2809 } 2810 return false; 2811 } 2812 }; 2813 2814 bool G1CollectedHeap::check_cset_heap_region_claim_values(jint claim_value) { 2815 CheckClaimValuesInCSetHRClosure cl(claim_value); 2816 collection_set_iterate(&cl); 2817 return cl.failures() == 0; 2818 } 2819 #endif // ASSERT 2820 2821 // Clear the cached CSet starting regions and (more importantly) 2822 // the time stamps. Called when we reset the GC time stamp. 2823 void G1CollectedHeap::clear_cset_start_regions() { 2824 assert(_worker_cset_start_region != NULL, "sanity"); 2825 assert(_worker_cset_start_region_time_stamp != NULL, "sanity"); 2826 2827 int n_queues = MAX2((int)ParallelGCThreads, 1); 2828 for (int i = 0; i < n_queues; i++) { 2829 _worker_cset_start_region[i] = NULL; 2830 _worker_cset_start_region_time_stamp[i] = 0; 2831 } 2832 } 2833 2834 // Given the id of a worker, obtain or calculate a suitable 2835 // starting region for iterating over the current collection set. 2836 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) { 2837 assert(get_gc_time_stamp() > 0, "should have been updated by now"); 2838 2839 HeapRegion* result = NULL; 2840 unsigned gc_time_stamp = get_gc_time_stamp(); 2841 2842 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) { 2843 // Cached starting region for current worker was set 2844 // during the current pause - so it's valid. 2845 // Note: the cached starting heap region may be NULL 2846 // (when the collection set is empty). 2847 result = _worker_cset_start_region[worker_i]; 2848 assert(result == NULL || result->in_collection_set(), "sanity"); 2849 return result; 2850 } 2851 2852 // The cached entry was not valid so let's calculate 2853 // a suitable starting heap region for this worker. 2854 2855 // We want the parallel threads to start their collection 2856 // set iteration at different collection set regions to 2857 // avoid contention. 2858 // If we have: 2859 // n collection set regions 2860 // p threads 2861 // Then thread t will start at region floor ((t * n) / p) 2862 2863 result = g1_policy()->collection_set(); 2864 if (G1CollectedHeap::use_parallel_gc_threads()) { 2865 uint cs_size = g1_policy()->cset_region_length(); 2866 uint active_workers = workers()->active_workers(); 2867 assert(UseDynamicNumberOfGCThreads || 2868 active_workers == workers()->total_workers(), 2869 "Unless dynamic should use total workers"); 2870 2871 uint end_ind = (cs_size * worker_i) / active_workers; 2872 uint start_ind = 0; 2873 2874 if (worker_i > 0 && 2875 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) { 2876 // Previous workers starting region is valid 2877 // so let's iterate from there 2878 start_ind = (cs_size * (worker_i - 1)) / active_workers; 2879 result = _worker_cset_start_region[worker_i - 1]; 2880 } 2881 2882 for (uint i = start_ind; i < end_ind; i++) { 2883 result = result->next_in_collection_set(); 2884 } 2885 } 2886 2887 // Note: the calculated starting heap region may be NULL 2888 // (when the collection set is empty). 2889 assert(result == NULL || result->in_collection_set(), "sanity"); 2890 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp, 2891 "should be updated only once per pause"); 2892 _worker_cset_start_region[worker_i] = result; 2893 OrderAccess::storestore(); 2894 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp; 2895 return result; 2896 } 2897 2898 HeapRegion* G1CollectedHeap::start_region_for_worker(uint worker_i, 2899 uint no_of_par_workers) { 2900 uint worker_num = 2901 G1CollectedHeap::use_parallel_gc_threads() ? no_of_par_workers : 1U; 2902 assert(UseDynamicNumberOfGCThreads || 2903 no_of_par_workers == workers()->total_workers(), 2904 "Non dynamic should use fixed number of workers"); 2905 const uint start_index = n_regions() * worker_i / worker_num; 2906 return region_at(start_index); 2907 } 2908 2909 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) { 2910 HeapRegion* r = g1_policy()->collection_set(); 2911 while (r != NULL) { 2912 HeapRegion* next = r->next_in_collection_set(); 2913 if (cl->doHeapRegion(r)) { 2914 cl->incomplete(); 2915 return; 2916 } 2917 r = next; 2918 } 2919 } 2920 2921 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r, 2922 HeapRegionClosure *cl) { 2923 if (r == NULL) { 2924 // The CSet is empty so there's nothing to do. 2925 return; 2926 } 2927 2928 assert(r->in_collection_set(), 2929 "Start region must be a member of the collection set."); 2930 HeapRegion* cur = r; 2931 while (cur != NULL) { 2932 HeapRegion* next = cur->next_in_collection_set(); 2933 if (cl->doHeapRegion(cur) && false) { 2934 cl->incomplete(); 2935 return; 2936 } 2937 cur = next; 2938 } 2939 cur = g1_policy()->collection_set(); 2940 while (cur != r) { 2941 HeapRegion* next = cur->next_in_collection_set(); 2942 if (cl->doHeapRegion(cur) && false) { 2943 cl->incomplete(); 2944 return; 2945 } 2946 cur = next; 2947 } 2948 } 2949 2950 CompactibleSpace* G1CollectedHeap::first_compactible_space() { 2951 return n_regions() > 0 ? region_at(0) : NULL; 2952 } 2953 2954 2955 Space* G1CollectedHeap::space_containing(const void* addr) const { 2956 return heap_region_containing(addr); 2957 } 2958 2959 HeapWord* G1CollectedHeap::block_start(const void* addr) const { 2960 Space* sp = space_containing(addr); 2961 return sp->block_start(addr); 2962 } 2963 2964 size_t G1CollectedHeap::block_size(const HeapWord* addr) const { 2965 Space* sp = space_containing(addr); 2966 return sp->block_size(addr); 2967 } 2968 2969 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { 2970 Space* sp = space_containing(addr); 2971 return sp->block_is_obj(addr); 2972 } 2973 2974 bool G1CollectedHeap::supports_tlab_allocation() const { 2975 return true; 2976 } 2977 2978 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { 2979 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes; 2980 } 2981 2982 size_t G1CollectedHeap::tlab_used(Thread* ignored) const { 2983 return young_list()->eden_used_bytes(); 2984 } 2985 2986 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size 2987 // must be smaller than the humongous object limit. 2988 size_t G1CollectedHeap::max_tlab_size() const { 2989 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment); 2990 } 2991 2992 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { 2993 // Return the remaining space in the cur alloc region, but not less than 2994 // the min TLAB size. 2995 2996 // Also, this value can be at most the humongous object threshold, 2997 // since we can't allow tlabs to grow big enough to accommodate 2998 // humongous objects. 2999 3000 HeapRegion* hr = _mutator_alloc_region.get(); 3001 size_t max_tlab = max_tlab_size() * wordSize; 3002 if (hr == NULL) { 3003 return max_tlab; 3004 } else { 3005 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab); 3006 } 3007 } 3008 3009 size_t G1CollectedHeap::max_capacity() const { 3010 return _g1_reserved.byte_size(); 3011 } 3012 3013 jlong G1CollectedHeap::millis_since_last_gc() { 3014 // assert(false, "NYI"); 3015 return 0; 3016 } 3017 3018 void G1CollectedHeap::prepare_for_verify() { 3019 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) { 3020 ensure_parsability(false); 3021 } 3022 g1_rem_set()->prepare_for_verify(); 3023 } 3024 3025 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr, 3026 VerifyOption vo) { 3027 switch (vo) { 3028 case VerifyOption_G1UsePrevMarking: 3029 return hr->obj_allocated_since_prev_marking(obj); 3030 case VerifyOption_G1UseNextMarking: 3031 return hr->obj_allocated_since_next_marking(obj); 3032 case VerifyOption_G1UseMarkWord: 3033 return false; 3034 default: 3035 ShouldNotReachHere(); 3036 } 3037 return false; // keep some compilers happy 3038 } 3039 3040 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) { 3041 switch (vo) { 3042 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start(); 3043 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start(); 3044 case VerifyOption_G1UseMarkWord: return NULL; 3045 default: ShouldNotReachHere(); 3046 } 3047 return NULL; // keep some compilers happy 3048 } 3049 3050 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) { 3051 switch (vo) { 3052 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj); 3053 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj); 3054 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked(); 3055 default: ShouldNotReachHere(); 3056 } 3057 return false; // keep some compilers happy 3058 } 3059 3060 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) { 3061 switch (vo) { 3062 case VerifyOption_G1UsePrevMarking: return "PTAMS"; 3063 case VerifyOption_G1UseNextMarking: return "NTAMS"; 3064 case VerifyOption_G1UseMarkWord: return "NONE"; 3065 default: ShouldNotReachHere(); 3066 } 3067 return NULL; // keep some compilers happy 3068 } 3069 3070 class VerifyRootsClosure: public OopClosure { 3071 private: 3072 G1CollectedHeap* _g1h; 3073 VerifyOption _vo; 3074 bool _failures; 3075 public: 3076 // _vo == UsePrevMarking -> use "prev" marking information, 3077 // _vo == UseNextMarking -> use "next" marking information, 3078 // _vo == UseMarkWord -> use mark word from object header. 3079 VerifyRootsClosure(VerifyOption vo) : 3080 _g1h(G1CollectedHeap::heap()), 3081 _vo(vo), 3082 _failures(false) { } 3083 3084 bool failures() { return _failures; } 3085 3086 template <class T> void do_oop_nv(T* p) { 3087 T heap_oop = oopDesc::load_heap_oop(p); 3088 if (!oopDesc::is_null(heap_oop)) { 3089 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 3090 if (_g1h->is_obj_dead_cond(obj, _vo)) { 3091 gclog_or_tty->print_cr("Root location "PTR_FORMAT" " 3092 "points to dead obj "PTR_FORMAT, p, (void*) obj); 3093 if (_vo == VerifyOption_G1UseMarkWord) { 3094 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark())); 3095 } 3096 obj->print_on(gclog_or_tty); 3097 _failures = true; 3098 } 3099 } 3100 } 3101 3102 void do_oop(oop* p) { do_oop_nv(p); } 3103 void do_oop(narrowOop* p) { do_oop_nv(p); } 3104 }; 3105 3106 class G1VerifyCodeRootOopClosure: public OopClosure { 3107 G1CollectedHeap* _g1h; 3108 OopClosure* _root_cl; 3109 nmethod* _nm; 3110 VerifyOption _vo; 3111 bool _failures; 3112 3113 template <class T> void do_oop_work(T* p) { 3114 // First verify that this root is live 3115 _root_cl->do_oop(p); 3116 3117 if (!G1VerifyHeapRegionCodeRoots) { 3118 // We're not verifying the code roots attached to heap region. 3119 return; 3120 } 3121 3122 // Don't check the code roots during marking verification in a full GC 3123 if (_vo == VerifyOption_G1UseMarkWord) { 3124 return; 3125 } 3126 3127 // Now verify that the current nmethod (which contains p) is 3128 // in the code root list of the heap region containing the 3129 // object referenced by p. 3130 3131 T heap_oop = oopDesc::load_heap_oop(p); 3132 if (!oopDesc::is_null(heap_oop)) { 3133 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 3134 3135 // Now fetch the region containing the object 3136 HeapRegion* hr = _g1h->heap_region_containing(obj); 3137 HeapRegionRemSet* hrrs = hr->rem_set(); 3138 // Verify that the strong code root list for this region 3139 // contains the nmethod 3140 if (!hrrs->strong_code_roots_list_contains(_nm)) { 3141 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" " 3142 "from nmethod "PTR_FORMAT" not in strong " 3143 "code roots for region ["PTR_FORMAT","PTR_FORMAT")", 3144 p, _nm, hr->bottom(), hr->end()); 3145 _failures = true; 3146 } 3147 } 3148 } 3149 3150 public: 3151 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo): 3152 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {} 3153 3154 void do_oop(oop* p) { do_oop_work(p); } 3155 void do_oop(narrowOop* p) { do_oop_work(p); } 3156 3157 void set_nmethod(nmethod* nm) { _nm = nm; } 3158 bool failures() { return _failures; } 3159 }; 3160 3161 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure { 3162 G1VerifyCodeRootOopClosure* _oop_cl; 3163 3164 public: 3165 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl): 3166 _oop_cl(oop_cl) {} 3167 3168 void do_code_blob(CodeBlob* cb) { 3169 nmethod* nm = cb->as_nmethod_or_null(); 3170 if (nm != NULL) { 3171 _oop_cl->set_nmethod(nm); 3172 nm->oops_do(_oop_cl); 3173 } 3174 } 3175 }; 3176 3177 class YoungRefCounterClosure : public OopClosure { 3178 G1CollectedHeap* _g1h; 3179 int _count; 3180 public: 3181 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {} 3182 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } } 3183 void do_oop(narrowOop* p) { ShouldNotReachHere(); } 3184 3185 int count() { return _count; } 3186 void reset_count() { _count = 0; }; 3187 }; 3188 3189 class VerifyKlassClosure: public KlassClosure { 3190 YoungRefCounterClosure _young_ref_counter_closure; 3191 OopClosure *_oop_closure; 3192 public: 3193 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {} 3194 void do_klass(Klass* k) { 3195 k->oops_do(_oop_closure); 3196 3197 _young_ref_counter_closure.reset_count(); 3198 k->oops_do(&_young_ref_counter_closure); 3199 if (_young_ref_counter_closure.count() > 0) { 3200 guarantee(k->has_modified_oops(), err_msg("Klass " PTR_FORMAT ", has young refs but is not dirty.", k)); 3201 } 3202 } 3203 }; 3204 3205 class VerifyLivenessOopClosure: public OopClosure { 3206 G1CollectedHeap* _g1h; 3207 VerifyOption _vo; 3208 public: 3209 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo): 3210 _g1h(g1h), _vo(vo) 3211 { } 3212 void do_oop(narrowOop *p) { do_oop_work(p); } 3213 void do_oop( oop *p) { do_oop_work(p); } 3214 3215 template <class T> void do_oop_work(T *p) { 3216 oop obj = oopDesc::load_decode_heap_oop(p); 3217 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo), 3218 "Dead object referenced by a not dead object"); 3219 } 3220 }; 3221 3222 class VerifyObjsInRegionClosure: public ObjectClosure { 3223 private: 3224 G1CollectedHeap* _g1h; 3225 size_t _live_bytes; 3226 HeapRegion *_hr; 3227 VerifyOption _vo; 3228 public: 3229 // _vo == UsePrevMarking -> use "prev" marking information, 3230 // _vo == UseNextMarking -> use "next" marking information, 3231 // _vo == UseMarkWord -> use mark word from object header. 3232 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo) 3233 : _live_bytes(0), _hr(hr), _vo(vo) { 3234 _g1h = G1CollectedHeap::heap(); 3235 } 3236 void do_object(oop o) { 3237 VerifyLivenessOopClosure isLive(_g1h, _vo); 3238 assert(o != NULL, "Huh?"); 3239 if (!_g1h->is_obj_dead_cond(o, _vo)) { 3240 // If the object is alive according to the mark word, 3241 // then verify that the marking information agrees. 3242 // Note we can't verify the contra-positive of the 3243 // above: if the object is dead (according to the mark 3244 // word), it may not be marked, or may have been marked 3245 // but has since became dead, or may have been allocated 3246 // since the last marking. 3247 if (_vo == VerifyOption_G1UseMarkWord) { 3248 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch"); 3249 } 3250 3251 o->oop_iterate_no_header(&isLive); 3252 if (!_hr->obj_allocated_since_prev_marking(o)) { 3253 size_t obj_size = o->size(); // Make sure we don't overflow 3254 _live_bytes += (obj_size * HeapWordSize); 3255 } 3256 } 3257 } 3258 size_t live_bytes() { return _live_bytes; } 3259 }; 3260 3261 class PrintObjsInRegionClosure : public ObjectClosure { 3262 HeapRegion *_hr; 3263 G1CollectedHeap *_g1; 3264 public: 3265 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) { 3266 _g1 = G1CollectedHeap::heap(); 3267 }; 3268 3269 void do_object(oop o) { 3270 if (o != NULL) { 3271 HeapWord *start = (HeapWord *) o; 3272 size_t word_sz = o->size(); 3273 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT 3274 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n", 3275 (void*) o, word_sz, 3276 _g1->isMarkedPrev(o), 3277 _g1->isMarkedNext(o), 3278 _hr->obj_allocated_since_prev_marking(o)); 3279 HeapWord *end = start + word_sz; 3280 HeapWord *cur; 3281 int *val; 3282 for (cur = start; cur < end; cur++) { 3283 val = (int *) cur; 3284 gclog_or_tty->print("\t "PTR_FORMAT":%d\n", val, *val); 3285 } 3286 } 3287 } 3288 }; 3289 3290 class VerifyRegionClosure: public HeapRegionClosure { 3291 private: 3292 bool _par; 3293 VerifyOption _vo; 3294 bool _failures; 3295 public: 3296 // _vo == UsePrevMarking -> use "prev" marking information, 3297 // _vo == UseNextMarking -> use "next" marking information, 3298 // _vo == UseMarkWord -> use mark word from object header. 3299 VerifyRegionClosure(bool par, VerifyOption vo) 3300 : _par(par), 3301 _vo(vo), 3302 _failures(false) {} 3303 3304 bool failures() { 3305 return _failures; 3306 } 3307 3308 bool doHeapRegion(HeapRegion* r) { 3309 if (!r->continuesHumongous()) { 3310 bool failures = false; 3311 r->verify(_vo, &failures); 3312 if (failures) { 3313 _failures = true; 3314 } else { 3315 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo); 3316 r->object_iterate(¬_dead_yet_cl); 3317 if (_vo != VerifyOption_G1UseNextMarking) { 3318 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) { 3319 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] " 3320 "max_live_bytes "SIZE_FORMAT" " 3321 "< calculated "SIZE_FORMAT, 3322 r->bottom(), r->end(), 3323 r->max_live_bytes(), 3324 not_dead_yet_cl.live_bytes()); 3325 _failures = true; 3326 } 3327 } else { 3328 // When vo == UseNextMarking we cannot currently do a sanity 3329 // check on the live bytes as the calculation has not been 3330 // finalized yet. 3331 } 3332 } 3333 } 3334 return false; // stop the region iteration if we hit a failure 3335 } 3336 }; 3337 3338 // This is the task used for parallel verification of the heap regions 3339 3340 class G1ParVerifyTask: public AbstractGangTask { 3341 private: 3342 G1CollectedHeap* _g1h; 3343 VerifyOption _vo; 3344 bool _failures; 3345 3346 public: 3347 // _vo == UsePrevMarking -> use "prev" marking information, 3348 // _vo == UseNextMarking -> use "next" marking information, 3349 // _vo == UseMarkWord -> use mark word from object header. 3350 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) : 3351 AbstractGangTask("Parallel verify task"), 3352 _g1h(g1h), 3353 _vo(vo), 3354 _failures(false) { } 3355 3356 bool failures() { 3357 return _failures; 3358 } 3359 3360 void work(uint worker_id) { 3361 HandleMark hm; 3362 VerifyRegionClosure blk(true, _vo); 3363 _g1h->heap_region_par_iterate_chunked(&blk, worker_id, 3364 _g1h->workers()->active_workers(), 3365 HeapRegion::ParVerifyClaimValue); 3366 if (blk.failures()) { 3367 _failures = true; 3368 } 3369 } 3370 }; 3371 3372 void G1CollectedHeap::verify(bool silent, VerifyOption vo) { 3373 if (SafepointSynchronize::is_at_safepoint()) { 3374 assert(Thread::current()->is_VM_thread(), 3375 "Expected to be executed serially by the VM thread at this point"); 3376 3377 if (!silent) { gclog_or_tty->print("Roots "); } 3378 VerifyRootsClosure rootsCl(vo); 3379 VerifyKlassClosure klassCl(this, &rootsCl); 3380 3381 // We apply the relevant closures to all the oops in the 3382 // system dictionary, class loader data graph and the string table. 3383 // Don't verify the code cache here, since it's verified below. 3384 const int so = SO_AllClasses | SO_Strings; 3385 3386 // Need cleared claim bits for the strong roots processing 3387 ClassLoaderDataGraph::clear_claimed_marks(); 3388 3389 process_strong_roots(true, // activate StrongRootsScope 3390 ScanningOption(so), // roots scanning options 3391 &rootsCl, 3392 &klassCl 3393 ); 3394 3395 // Verify the nmethods in the code cache. 3396 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo); 3397 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl); 3398 CodeCache::blobs_do(&blobsCl); 3399 3400 bool failures = rootsCl.failures() || codeRootsCl.failures(); 3401 3402 if (vo != VerifyOption_G1UseMarkWord) { 3403 // If we're verifying during a full GC then the region sets 3404 // will have been torn down at the start of the GC. Therefore 3405 // verifying the region sets will fail. So we only verify 3406 // the region sets when not in a full GC. 3407 if (!silent) { gclog_or_tty->print("HeapRegionSets "); } 3408 verify_region_sets(); 3409 } 3410 3411 if (!silent) { gclog_or_tty->print("HeapRegions "); } 3412 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) { 3413 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue), 3414 "sanity check"); 3415 3416 G1ParVerifyTask task(this, vo); 3417 assert(UseDynamicNumberOfGCThreads || 3418 workers()->active_workers() == workers()->total_workers(), 3419 "If not dynamic should be using all the workers"); 3420 int n_workers = workers()->active_workers(); 3421 set_par_threads(n_workers); 3422 workers()->run_task(&task); 3423 set_par_threads(0); 3424 if (task.failures()) { 3425 failures = true; 3426 } 3427 3428 // Checks that the expected amount of parallel work was done. 3429 // The implication is that n_workers is > 0. 3430 assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue), 3431 "sanity check"); 3432 3433 reset_heap_region_claim_values(); 3434 3435 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue), 3436 "sanity check"); 3437 } else { 3438 VerifyRegionClosure blk(false, vo); 3439 heap_region_iterate(&blk); 3440 if (blk.failures()) { 3441 failures = true; 3442 } 3443 } 3444 if (!silent) gclog_or_tty->print("RemSet "); 3445 rem_set()->verify(); 3446 3447 if (G1StringDedup::is_enabled()) { 3448 if (!silent) gclog_or_tty->print("StrDedup "); 3449 G1StringDedup::verify(); 3450 } 3451 3452 if (failures) { 3453 gclog_or_tty->print_cr("Heap:"); 3454 // It helps to have the per-region information in the output to 3455 // help us track down what went wrong. This is why we call 3456 // print_extended_on() instead of print_on(). 3457 print_extended_on(gclog_or_tty); 3458 gclog_or_tty->print_cr(""); 3459 #ifndef PRODUCT 3460 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) { 3461 concurrent_mark()->print_reachable("at-verification-failure", 3462 vo, false /* all */); 3463 } 3464 #endif 3465 gclog_or_tty->flush(); 3466 } 3467 guarantee(!failures, "there should not have been any failures"); 3468 } else { 3469 if (!silent) { 3470 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet"); 3471 if (G1StringDedup::is_enabled()) { 3472 gclog_or_tty->print(", StrDedup"); 3473 } 3474 gclog_or_tty->print(") "); 3475 } 3476 } 3477 } 3478 3479 void G1CollectedHeap::verify(bool silent) { 3480 verify(silent, VerifyOption_G1UsePrevMarking); 3481 } 3482 3483 double G1CollectedHeap::verify(bool guard, const char* msg) { 3484 double verify_time_ms = 0.0; 3485 3486 if (guard && total_collections() >= VerifyGCStartAt) { 3487 double verify_start = os::elapsedTime(); 3488 HandleMark hm; // Discard invalid handles created during verification 3489 prepare_for_verify(); 3490 Universe::verify(VerifyOption_G1UsePrevMarking, msg); 3491 verify_time_ms = (os::elapsedTime() - verify_start) * 1000; 3492 } 3493 3494 return verify_time_ms; 3495 } 3496 3497 void G1CollectedHeap::verify_before_gc() { 3498 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:"); 3499 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms); 3500 } 3501 3502 void G1CollectedHeap::verify_after_gc() { 3503 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:"); 3504 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms); 3505 } 3506 3507 class PrintRegionClosure: public HeapRegionClosure { 3508 outputStream* _st; 3509 public: 3510 PrintRegionClosure(outputStream* st) : _st(st) {} 3511 bool doHeapRegion(HeapRegion* r) { 3512 r->print_on(_st); 3513 return false; 3514 } 3515 }; 3516 3517 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 3518 const HeapRegion* hr, 3519 const VerifyOption vo) const { 3520 switch (vo) { 3521 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); 3522 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); 3523 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked(); 3524 default: ShouldNotReachHere(); 3525 } 3526 return false; // keep some compilers happy 3527 } 3528 3529 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 3530 const VerifyOption vo) const { 3531 switch (vo) { 3532 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); 3533 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); 3534 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked(); 3535 default: ShouldNotReachHere(); 3536 } 3537 return false; // keep some compilers happy 3538 } 3539 3540 void G1CollectedHeap::print_on(outputStream* st) const { 3541 st->print(" %-20s", "garbage-first heap"); 3542 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 3543 capacity()/K, used_unlocked()/K); 3544 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")", 3545 _g1_storage.low_boundary(), 3546 _g1_storage.high(), 3547 _g1_storage.high_boundary()); 3548 st->cr(); 3549 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); 3550 uint young_regions = _young_list->length(); 3551 st->print("%u young (" SIZE_FORMAT "K), ", young_regions, 3552 (size_t) young_regions * HeapRegion::GrainBytes / K); 3553 uint survivor_regions = g1_policy()->recorded_survivor_regions(); 3554 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, 3555 (size_t) survivor_regions * HeapRegion::GrainBytes / K); 3556 st->cr(); 3557 MetaspaceAux::print_on(st); 3558 } 3559 3560 void G1CollectedHeap::print_extended_on(outputStream* st) const { 3561 print_on(st); 3562 3563 // Print the per-region information. 3564 st->cr(); 3565 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), " 3566 "HS=humongous(starts), HC=humongous(continues), " 3567 "CS=collection set, F=free, TS=gc time stamp, " 3568 "PTAMS=previous top-at-mark-start, " 3569 "NTAMS=next top-at-mark-start)"); 3570 PrintRegionClosure blk(st); 3571 heap_region_iterate(&blk); 3572 } 3573 3574 void G1CollectedHeap::print_on_error(outputStream* st) const { 3575 this->CollectedHeap::print_on_error(st); 3576 3577 if (_cm != NULL) { 3578 st->cr(); 3579 _cm->print_on_error(st); 3580 } 3581 } 3582 3583 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const { 3584 if (G1CollectedHeap::use_parallel_gc_threads()) { 3585 workers()->print_worker_threads_on(st); 3586 } 3587 _cmThread->print_on(st); 3588 st->cr(); 3589 _cm->print_worker_threads_on(st); 3590 _cg1r->print_worker_threads_on(st); 3591 if (G1StringDedup::is_enabled()) { 3592 G1StringDedup::print_worker_threads_on(st); 3593 } 3594 } 3595 3596 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { 3597 if (G1CollectedHeap::use_parallel_gc_threads()) { 3598 workers()->threads_do(tc); 3599 } 3600 tc->do_thread(_cmThread); 3601 _cg1r->threads_do(tc); 3602 if (G1StringDedup::is_enabled()) { 3603 G1StringDedup::threads_do(tc); 3604 } 3605 } 3606 3607 void G1CollectedHeap::print_tracing_info() const { 3608 // We'll overload this to mean "trace GC pause statistics." 3609 if (TraceGen0Time || TraceGen1Time) { 3610 // The "G1CollectorPolicy" is keeping track of these stats, so delegate 3611 // to that. 3612 g1_policy()->print_tracing_info(); 3613 } 3614 if (G1SummarizeRSetStats) { 3615 g1_rem_set()->print_summary_info(); 3616 } 3617 if (G1SummarizeConcMark) { 3618 concurrent_mark()->print_summary_info(); 3619 } 3620 g1_policy()->print_yg_surv_rate_info(); 3621 SpecializationStats::print(); 3622 } 3623 3624 #ifndef PRODUCT 3625 // Helpful for debugging RSet issues. 3626 3627 class PrintRSetsClosure : public HeapRegionClosure { 3628 private: 3629 const char* _msg; 3630 size_t _occupied_sum; 3631 3632 public: 3633 bool doHeapRegion(HeapRegion* r) { 3634 HeapRegionRemSet* hrrs = r->rem_set(); 3635 size_t occupied = hrrs->occupied(); 3636 _occupied_sum += occupied; 3637 3638 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT, 3639 HR_FORMAT_PARAMS(r)); 3640 if (occupied == 0) { 3641 gclog_or_tty->print_cr(" RSet is empty"); 3642 } else { 3643 hrrs->print(); 3644 } 3645 gclog_or_tty->print_cr("----------"); 3646 return false; 3647 } 3648 3649 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { 3650 gclog_or_tty->cr(); 3651 gclog_or_tty->print_cr("========================================"); 3652 gclog_or_tty->print_cr(msg); 3653 gclog_or_tty->cr(); 3654 } 3655 3656 ~PrintRSetsClosure() { 3657 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum); 3658 gclog_or_tty->print_cr("========================================"); 3659 gclog_or_tty->cr(); 3660 } 3661 }; 3662 3663 void G1CollectedHeap::print_cset_rsets() { 3664 PrintRSetsClosure cl("Printing CSet RSets"); 3665 collection_set_iterate(&cl); 3666 } 3667 3668 void G1CollectedHeap::print_all_rsets() { 3669 PrintRSetsClosure cl("Printing All RSets");; 3670 heap_region_iterate(&cl); 3671 } 3672 #endif // PRODUCT 3673 3674 G1CollectedHeap* G1CollectedHeap::heap() { 3675 assert(_sh->kind() == CollectedHeap::G1CollectedHeap, 3676 "not a garbage-first heap"); 3677 return _g1h; 3678 } 3679 3680 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) { 3681 // always_do_update_barrier = false; 3682 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 3683 // Fill TLAB's and such 3684 accumulate_statistics_all_tlabs(); 3685 ensure_parsability(true); 3686 3687 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) && 3688 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) { 3689 g1_rem_set()->print_periodic_summary_info("Before GC RS summary"); 3690 } 3691 } 3692 3693 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) { 3694 3695 if (G1SummarizeRSetStats && 3696 (G1SummarizeRSetStatsPeriod > 0) && 3697 // we are at the end of the GC. Total collections has already been increased. 3698 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) { 3699 g1_rem_set()->print_periodic_summary_info("After GC RS summary"); 3700 } 3701 3702 // FIXME: what is this about? 3703 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" 3704 // is set. 3705 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(), 3706 "derived pointer present")); 3707 // always_do_update_barrier = true; 3708 3709 resize_all_tlabs(); 3710 3711 // We have just completed a GC. Update the soft reference 3712 // policy with the new heap occupancy 3713 Universe::update_heap_info_at_gc(); 3714 } 3715 3716 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, 3717 unsigned int gc_count_before, 3718 bool* succeeded, 3719 GCCause::Cause gc_cause) { 3720 assert_heap_not_locked_and_not_at_safepoint(); 3721 g1_policy()->record_stop_world_start(); 3722 VM_G1IncCollectionPause op(gc_count_before, 3723 word_size, 3724 false, /* should_initiate_conc_mark */ 3725 g1_policy()->max_pause_time_ms(), 3726 gc_cause); 3727 VMThread::execute(&op); 3728 3729 HeapWord* result = op.result(); 3730 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded(); 3731 assert(result == NULL || ret_succeeded, 3732 "the result should be NULL if the VM did not succeed"); 3733 *succeeded = ret_succeeded; 3734 3735 assert_heap_not_locked(); 3736 return result; 3737 } 3738 3739 void 3740 G1CollectedHeap::doConcurrentMark() { 3741 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); 3742 if (!_cmThread->in_progress()) { 3743 _cmThread->set_started(); 3744 CGC_lock->notify(); 3745 } 3746 } 3747 3748 size_t G1CollectedHeap::pending_card_num() { 3749 size_t extra_cards = 0; 3750 JavaThread *curr = Threads::first(); 3751 while (curr != NULL) { 3752 DirtyCardQueue& dcq = curr->dirty_card_queue(); 3753 extra_cards += dcq.size(); 3754 curr = curr->next(); 3755 } 3756 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 3757 size_t buffer_size = dcqs.buffer_size(); 3758 size_t buffer_num = dcqs.completed_buffers_num(); 3759 3760 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes 3761 // in bytes - not the number of 'entries'. We need to convert 3762 // into a number of cards. 3763 return (buffer_size * buffer_num + extra_cards) / oopSize; 3764 } 3765 3766 size_t G1CollectedHeap::cards_scanned() { 3767 return g1_rem_set()->cardsScanned(); 3768 } 3769 3770 void 3771 G1CollectedHeap::setup_surviving_young_words() { 3772 assert(_surviving_young_words == NULL, "pre-condition"); 3773 uint array_length = g1_policy()->young_cset_region_length(); 3774 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC); 3775 if (_surviving_young_words == NULL) { 3776 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR, 3777 "Not enough space for young surv words summary."); 3778 } 3779 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t)); 3780 #ifdef ASSERT 3781 for (uint i = 0; i < array_length; ++i) { 3782 assert( _surviving_young_words[i] == 0, "memset above" ); 3783 } 3784 #endif // !ASSERT 3785 } 3786 3787 void 3788 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) { 3789 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); 3790 uint array_length = g1_policy()->young_cset_region_length(); 3791 for (uint i = 0; i < array_length; ++i) { 3792 _surviving_young_words[i] += surv_young_words[i]; 3793 } 3794 } 3795 3796 void 3797 G1CollectedHeap::cleanup_surviving_young_words() { 3798 guarantee( _surviving_young_words != NULL, "pre-condition" ); 3799 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words, mtGC); 3800 _surviving_young_words = NULL; 3801 } 3802 3803 #ifdef ASSERT 3804 class VerifyCSetClosure: public HeapRegionClosure { 3805 public: 3806 bool doHeapRegion(HeapRegion* hr) { 3807 // Here we check that the CSet region's RSet is ready for parallel 3808 // iteration. The fields that we'll verify are only manipulated 3809 // when the region is part of a CSet and is collected. Afterwards, 3810 // we reset these fields when we clear the region's RSet (when the 3811 // region is freed) so they are ready when the region is 3812 // re-allocated. The only exception to this is if there's an 3813 // evacuation failure and instead of freeing the region we leave 3814 // it in the heap. In that case, we reset these fields during 3815 // evacuation failure handling. 3816 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification"); 3817 3818 // Here's a good place to add any other checks we'd like to 3819 // perform on CSet regions. 3820 return false; 3821 } 3822 }; 3823 #endif // ASSERT 3824 3825 #if TASKQUEUE_STATS 3826 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) { 3827 st->print_raw_cr("GC Task Stats"); 3828 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); 3829 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); 3830 } 3831 3832 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const { 3833 print_taskqueue_stats_hdr(st); 3834 3835 TaskQueueStats totals; 3836 const int n = workers() != NULL ? workers()->total_workers() : 1; 3837 for (int i = 0; i < n; ++i) { 3838 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr(); 3839 totals += task_queue(i)->stats; 3840 } 3841 st->print_raw("tot "); totals.print(st); st->cr(); 3842 3843 DEBUG_ONLY(totals.verify()); 3844 } 3845 3846 void G1CollectedHeap::reset_taskqueue_stats() { 3847 const int n = workers() != NULL ? workers()->total_workers() : 1; 3848 for (int i = 0; i < n; ++i) { 3849 task_queue(i)->stats.reset(); 3850 } 3851 } 3852 #endif // TASKQUEUE_STATS 3853 3854 void G1CollectedHeap::log_gc_header() { 3855 if (!G1Log::fine()) { 3856 return; 3857 } 3858 3859 gclog_or_tty->date_stamp(PrintGCDateStamps); 3860 gclog_or_tty->stamp(PrintGCTimeStamps); 3861 3862 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause()) 3863 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)") 3864 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : ""); 3865 3866 gclog_or_tty->print("[%s", (const char*)gc_cause_str); 3867 } 3868 3869 void G1CollectedHeap::log_gc_footer(double pause_time_sec) { 3870 if (!G1Log::fine()) { 3871 return; 3872 } 3873 3874 if (G1Log::finer()) { 3875 if (evacuation_failed()) { 3876 gclog_or_tty->print(" (to-space exhausted)"); 3877 } 3878 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec); 3879 g1_policy()->phase_times()->note_gc_end(); 3880 g1_policy()->phase_times()->print(pause_time_sec); 3881 g1_policy()->print_detailed_heap_transition(); 3882 } else { 3883 if (evacuation_failed()) { 3884 gclog_or_tty->print("--"); 3885 } 3886 g1_policy()->print_heap_transition(); 3887 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec); 3888 } 3889 gclog_or_tty->flush(); 3890 } 3891 3892 bool 3893 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { 3894 assert_at_safepoint(true /* should_be_vm_thread */); 3895 guarantee(!is_gc_active(), "collection is not reentrant"); 3896 3897 if (GC_locker::check_active_before_gc()) { 3898 return false; 3899 } 3900 3901 _gc_timer_stw->register_gc_start(); 3902 3903 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start()); 3904 3905 SvcGCMarker sgcm(SvcGCMarker::MINOR); 3906 ResourceMark rm; 3907 3908 print_heap_before_gc(); 3909 trace_heap_before_gc(_gc_tracer_stw); 3910 3911 verify_region_sets_optional(); 3912 verify_dirty_young_regions(); 3913 3914 // This call will decide whether this pause is an initial-mark 3915 // pause. If it is, during_initial_mark_pause() will return true 3916 // for the duration of this pause. 3917 g1_policy()->decide_on_conc_mark_initiation(); 3918 3919 // We do not allow initial-mark to be piggy-backed on a mixed GC. 3920 assert(!g1_policy()->during_initial_mark_pause() || 3921 g1_policy()->gcs_are_young(), "sanity"); 3922 3923 // We also do not allow mixed GCs during marking. 3924 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity"); 3925 3926 // Record whether this pause is an initial mark. When the current 3927 // thread has completed its logging output and it's safe to signal 3928 // the CM thread, the flag's value in the policy has been reset. 3929 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause(); 3930 3931 // Inner scope for scope based logging, timers, and stats collection 3932 { 3933 EvacuationInfo evacuation_info; 3934 3935 if (g1_policy()->during_initial_mark_pause()) { 3936 // We are about to start a marking cycle, so we increment the 3937 // full collection counter. 3938 increment_old_marking_cycles_started(); 3939 register_concurrent_cycle_start(_gc_timer_stw->gc_start()); 3940 } 3941 3942 _gc_tracer_stw->report_yc_type(yc_type()); 3943 3944 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty); 3945 3946 int active_workers = (G1CollectedHeap::use_parallel_gc_threads() ? 3947 workers()->active_workers() : 1); 3948 double pause_start_sec = os::elapsedTime(); 3949 g1_policy()->phase_times()->note_gc_start(active_workers); 3950 log_gc_header(); 3951 3952 TraceCollectorStats tcs(g1mm()->incremental_collection_counters()); 3953 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause()); 3954 3955 // If the secondary_free_list is not empty, append it to the 3956 // free_list. No need to wait for the cleanup operation to finish; 3957 // the region allocation code will check the secondary_free_list 3958 // and wait if necessary. If the G1StressConcRegionFreeing flag is 3959 // set, skip this step so that the region allocation code has to 3960 // get entries from the secondary_free_list. 3961 if (!G1StressConcRegionFreeing) { 3962 append_secondary_free_list_if_not_empty_with_lock(); 3963 } 3964 3965 assert(check_young_list_well_formed(), "young list should be well formed"); 3966 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue), 3967 "sanity check"); 3968 3969 // Don't dynamically change the number of GC threads this early. A value of 3970 // 0 is used to indicate serial work. When parallel work is done, 3971 // it will be set. 3972 3973 { // Call to jvmpi::post_class_unload_events must occur outside of active GC 3974 IsGCActiveMark x; 3975 3976 gc_prologue(false); 3977 increment_total_collections(false /* full gc */); 3978 increment_gc_time_stamp(); 3979 3980 verify_before_gc(); 3981 3982 COMPILER2_PRESENT(DerivedPointerTable::clear()); 3983 3984 // Please see comment in g1CollectedHeap.hpp and 3985 // G1CollectedHeap::ref_processing_init() to see how 3986 // reference processing currently works in G1. 3987 3988 // Enable discovery in the STW reference processor 3989 ref_processor_stw()->enable_discovery(true /*verify_disabled*/, 3990 true /*verify_no_refs*/); 3991 3992 { 3993 // We want to temporarily turn off discovery by the 3994 // CM ref processor, if necessary, and turn it back on 3995 // on again later if we do. Using a scoped 3996 // NoRefDiscovery object will do this. 3997 NoRefDiscovery no_cm_discovery(ref_processor_cm()); 3998 3999 // Forget the current alloc region (we might even choose it to be part 4000 // of the collection set!). 4001 release_mutator_alloc_region(); 4002 4003 // We should call this after we retire the mutator alloc 4004 // region(s) so that all the ALLOC / RETIRE events are generated 4005 // before the start GC event. 4006 _hr_printer.start_gc(false /* full */, (size_t) total_collections()); 4007 4008 // This timing is only used by the ergonomics to handle our pause target. 4009 // It is unclear why this should not include the full pause. We will 4010 // investigate this in CR 7178365. 4011 // 4012 // Preserving the old comment here if that helps the investigation: 4013 // 4014 // The elapsed time induced by the start time below deliberately elides 4015 // the possible verification above. 4016 double sample_start_time_sec = os::elapsedTime(); 4017 4018 #if YOUNG_LIST_VERBOSE 4019 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:"); 4020 _young_list->print(); 4021 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 4022 #endif // YOUNG_LIST_VERBOSE 4023 4024 g1_policy()->record_collection_pause_start(sample_start_time_sec); 4025 4026 double scan_wait_start = os::elapsedTime(); 4027 // We have to wait until the CM threads finish scanning the 4028 // root regions as it's the only way to ensure that all the 4029 // objects on them have been correctly scanned before we start 4030 // moving them during the GC. 4031 bool waited = _cm->root_regions()->wait_until_scan_finished(); 4032 double wait_time_ms = 0.0; 4033 if (waited) { 4034 double scan_wait_end = os::elapsedTime(); 4035 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0; 4036 } 4037 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms); 4038 4039 #if YOUNG_LIST_VERBOSE 4040 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:"); 4041 _young_list->print(); 4042 #endif // YOUNG_LIST_VERBOSE 4043 4044 if (g1_policy()->during_initial_mark_pause()) { 4045 concurrent_mark()->checkpointRootsInitialPre(); 4046 } 4047 4048 #if YOUNG_LIST_VERBOSE 4049 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:"); 4050 _young_list->print(); 4051 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 4052 #endif // YOUNG_LIST_VERBOSE 4053 4054 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info); 4055 4056 _cm->note_start_of_gc(); 4057 // We should not verify the per-thread SATB buffers given that 4058 // we have not filtered them yet (we'll do so during the 4059 // GC). We also call this after finalize_cset() to 4060 // ensure that the CSet has been finalized. 4061 _cm->verify_no_cset_oops(true /* verify_stacks */, 4062 true /* verify_enqueued_buffers */, 4063 false /* verify_thread_buffers */, 4064 true /* verify_fingers */); 4065 4066 if (_hr_printer.is_active()) { 4067 HeapRegion* hr = g1_policy()->collection_set(); 4068 while (hr != NULL) { 4069 G1HRPrinter::RegionType type; 4070 if (!hr->is_young()) { 4071 type = G1HRPrinter::Old; 4072 } else if (hr->is_survivor()) { 4073 type = G1HRPrinter::Survivor; 4074 } else { 4075 type = G1HRPrinter::Eden; 4076 } 4077 _hr_printer.cset(hr); 4078 hr = hr->next_in_collection_set(); 4079 } 4080 } 4081 4082 #ifdef ASSERT 4083 VerifyCSetClosure cl; 4084 collection_set_iterate(&cl); 4085 #endif // ASSERT 4086 4087 setup_surviving_young_words(); 4088 4089 // Initialize the GC alloc regions. 4090 init_gc_alloc_regions(evacuation_info); 4091 4092 // Actually do the work... 4093 evacuate_collection_set(evacuation_info); 4094 4095 // We do this to mainly verify the per-thread SATB buffers 4096 // (which have been filtered by now) since we didn't verify 4097 // them earlier. No point in re-checking the stacks / enqueued 4098 // buffers given that the CSet has not changed since last time 4099 // we checked. 4100 _cm->verify_no_cset_oops(false /* verify_stacks */, 4101 false /* verify_enqueued_buffers */, 4102 true /* verify_thread_buffers */, 4103 true /* verify_fingers */); 4104 4105 free_collection_set(g1_policy()->collection_set(), evacuation_info); 4106 g1_policy()->clear_collection_set(); 4107 4108 cleanup_surviving_young_words(); 4109 4110 // Start a new incremental collection set for the next pause. 4111 g1_policy()->start_incremental_cset_building(); 4112 4113 clear_cset_fast_test(); 4114 4115 _young_list->reset_sampled_info(); 4116 4117 // Don't check the whole heap at this point as the 4118 // GC alloc regions from this pause have been tagged 4119 // as survivors and moved on to the survivor list. 4120 // Survivor regions will fail the !is_young() check. 4121 assert(check_young_list_empty(false /* check_heap */), 4122 "young list should be empty"); 4123 4124 #if YOUNG_LIST_VERBOSE 4125 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:"); 4126 _young_list->print(); 4127 #endif // YOUNG_LIST_VERBOSE 4128 4129 g1_policy()->record_survivor_regions(_young_list->survivor_length(), 4130 _young_list->first_survivor_region(), 4131 _young_list->last_survivor_region()); 4132 4133 _young_list->reset_auxilary_lists(); 4134 4135 if (evacuation_failed()) { 4136 _summary_bytes_used = recalculate_used(); 4137 uint n_queues = MAX2((int)ParallelGCThreads, 1); 4138 for (uint i = 0; i < n_queues; i++) { 4139 if (_evacuation_failed_info_array[i].has_failed()) { 4140 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]); 4141 } 4142 } 4143 } else { 4144 // The "used" of the the collection set have already been subtracted 4145 // when they were freed. Add in the bytes evacuated. 4146 _summary_bytes_used += g1_policy()->bytes_copied_during_gc(); 4147 } 4148 4149 if (g1_policy()->during_initial_mark_pause()) { 4150 // We have to do this before we notify the CM threads that 4151 // they can start working to make sure that all the 4152 // appropriate initialization is done on the CM object. 4153 concurrent_mark()->checkpointRootsInitialPost(); 4154 set_marking_started(); 4155 // Note that we don't actually trigger the CM thread at 4156 // this point. We do that later when we're sure that 4157 // the current thread has completed its logging output. 4158 } 4159 4160 allocate_dummy_regions(); 4161 4162 #if YOUNG_LIST_VERBOSE 4163 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:"); 4164 _young_list->print(); 4165 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 4166 #endif // YOUNG_LIST_VERBOSE 4167 4168 init_mutator_alloc_region(); 4169 4170 { 4171 size_t expand_bytes = g1_policy()->expansion_amount(); 4172 if (expand_bytes > 0) { 4173 size_t bytes_before = capacity(); 4174 // No need for an ergo verbose message here, 4175 // expansion_amount() does this when it returns a value > 0. 4176 if (!expand(expand_bytes)) { 4177 // We failed to expand the heap so let's verify that 4178 // committed/uncommitted amount match the backing store 4179 assert(capacity() == _g1_storage.committed_size(), "committed size mismatch"); 4180 assert(max_capacity() == _g1_storage.reserved_size(), "reserved size mismatch"); 4181 } 4182 } 4183 } 4184 4185 // We redo the verification but now wrt to the new CSet which 4186 // has just got initialized after the previous CSet was freed. 4187 _cm->verify_no_cset_oops(true /* verify_stacks */, 4188 true /* verify_enqueued_buffers */, 4189 true /* verify_thread_buffers */, 4190 true /* verify_fingers */); 4191 _cm->note_end_of_gc(); 4192 4193 // This timing is only used by the ergonomics to handle our pause target. 4194 // It is unclear why this should not include the full pause. We will 4195 // investigate this in CR 7178365. 4196 double sample_end_time_sec = os::elapsedTime(); 4197 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; 4198 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info); 4199 4200 MemoryService::track_memory_usage(); 4201 4202 // In prepare_for_verify() below we'll need to scan the deferred 4203 // update buffers to bring the RSets up-to-date if 4204 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning 4205 // the update buffers we'll probably need to scan cards on the 4206 // regions we just allocated to (i.e., the GC alloc 4207 // regions). However, during the last GC we called 4208 // set_saved_mark() on all the GC alloc regions, so card 4209 // scanning might skip the [saved_mark_word()...top()] area of 4210 // those regions (i.e., the area we allocated objects into 4211 // during the last GC). But it shouldn't. Given that 4212 // saved_mark_word() is conditional on whether the GC time stamp 4213 // on the region is current or not, by incrementing the GC time 4214 // stamp here we invalidate all the GC time stamps on all the 4215 // regions and saved_mark_word() will simply return top() for 4216 // all the regions. This is a nicer way of ensuring this rather 4217 // than iterating over the regions and fixing them. In fact, the 4218 // GC time stamp increment here also ensures that 4219 // saved_mark_word() will return top() between pauses, i.e., 4220 // during concurrent refinement. So we don't need the 4221 // is_gc_active() check to decided which top to use when 4222 // scanning cards (see CR 7039627). 4223 increment_gc_time_stamp(); 4224 4225 verify_after_gc(); 4226 4227 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 4228 ref_processor_stw()->verify_no_references_recorded(); 4229 4230 // CM reference discovery will be re-enabled if necessary. 4231 } 4232 4233 // We should do this after we potentially expand the heap so 4234 // that all the COMMIT events are generated before the end GC 4235 // event, and after we retire the GC alloc regions so that all 4236 // RETIRE events are generated before the end GC event. 4237 _hr_printer.end_gc(false /* full */, (size_t) total_collections()); 4238 4239 if (mark_in_progress()) { 4240 concurrent_mark()->update_g1_committed(); 4241 } 4242 4243 #ifdef TRACESPINNING 4244 ParallelTaskTerminator::print_termination_counts(); 4245 #endif 4246 4247 gc_epilogue(false); 4248 } 4249 4250 // Print the remainder of the GC log output. 4251 log_gc_footer(os::elapsedTime() - pause_start_sec); 4252 4253 // It is not yet to safe to tell the concurrent mark to 4254 // start as we have some optional output below. We don't want the 4255 // output from the concurrent mark thread interfering with this 4256 // logging output either. 4257 4258 _hrs.verify_optional(); 4259 verify_region_sets_optional(); 4260 4261 TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats()); 4262 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); 4263 4264 print_heap_after_gc(); 4265 trace_heap_after_gc(_gc_tracer_stw); 4266 4267 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 4268 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 4269 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 4270 // before any GC notifications are raised. 4271 g1mm()->update_sizes(); 4272 4273 _gc_tracer_stw->report_evacuation_info(&evacuation_info); 4274 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold()); 4275 _gc_timer_stw->register_gc_end(); 4276 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions()); 4277 } 4278 // It should now be safe to tell the concurrent mark thread to start 4279 // without its logging output interfering with the logging output 4280 // that came from the pause. 4281 4282 if (should_start_conc_mark) { 4283 // CAUTION: after the doConcurrentMark() call below, 4284 // the concurrent marking thread(s) could be running 4285 // concurrently with us. Make sure that anything after 4286 // this point does not assume that we are the only GC thread 4287 // running. Note: of course, the actual marking work will 4288 // not start until the safepoint itself is released in 4289 // SuspendibleThreadSet::desynchronize(). 4290 doConcurrentMark(); 4291 } 4292 4293 return true; 4294 } 4295 4296 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose) 4297 { 4298 size_t gclab_word_size; 4299 switch (purpose) { 4300 case GCAllocForSurvived: 4301 gclab_word_size = _survivor_plab_stats.desired_plab_sz(); 4302 break; 4303 case GCAllocForTenured: 4304 gclab_word_size = _old_plab_stats.desired_plab_sz(); 4305 break; 4306 default: 4307 assert(false, "unknown GCAllocPurpose"); 4308 gclab_word_size = _old_plab_stats.desired_plab_sz(); 4309 break; 4310 } 4311 4312 // Prevent humongous PLAB sizes for two reasons: 4313 // * PLABs are allocated using a similar paths as oops, but should 4314 // never be in a humongous region 4315 // * Allowing humongous PLABs needlessly churns the region free lists 4316 return MIN2(_humongous_object_threshold_in_words, gclab_word_size); 4317 } 4318 4319 void G1CollectedHeap::init_mutator_alloc_region() { 4320 assert(_mutator_alloc_region.get() == NULL, "pre-condition"); 4321 _mutator_alloc_region.init(); 4322 } 4323 4324 void G1CollectedHeap::release_mutator_alloc_region() { 4325 _mutator_alloc_region.release(); 4326 assert(_mutator_alloc_region.get() == NULL, "post-condition"); 4327 } 4328 4329 void G1CollectedHeap::init_gc_alloc_regions(EvacuationInfo& evacuation_info) { 4330 assert_at_safepoint(true /* should_be_vm_thread */); 4331 4332 _survivor_gc_alloc_region.init(); 4333 _old_gc_alloc_region.init(); 4334 HeapRegion* retained_region = _retained_old_gc_alloc_region; 4335 _retained_old_gc_alloc_region = NULL; 4336 4337 // We will discard the current GC alloc region if: 4338 // a) it's in the collection set (it can happen!), 4339 // b) it's already full (no point in using it), 4340 // c) it's empty (this means that it was emptied during 4341 // a cleanup and it should be on the free list now), or 4342 // d) it's humongous (this means that it was emptied 4343 // during a cleanup and was added to the free list, but 4344 // has been subsequently used to allocate a humongous 4345 // object that may be less than the region size). 4346 if (retained_region != NULL && 4347 !retained_region->in_collection_set() && 4348 !(retained_region->top() == retained_region->end()) && 4349 !retained_region->is_empty() && 4350 !retained_region->isHumongous()) { 4351 retained_region->set_saved_mark(); 4352 // The retained region was added to the old region set when it was 4353 // retired. We have to remove it now, since we don't allow regions 4354 // we allocate to in the region sets. We'll re-add it later, when 4355 // it's retired again. 4356 _old_set.remove(retained_region); 4357 bool during_im = g1_policy()->during_initial_mark_pause(); 4358 retained_region->note_start_of_copying(during_im); 4359 _old_gc_alloc_region.set(retained_region); 4360 _hr_printer.reuse(retained_region); 4361 evacuation_info.set_alloc_regions_used_before(retained_region->used()); 4362 } 4363 } 4364 4365 void G1CollectedHeap::release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info) { 4366 evacuation_info.set_allocation_regions(_survivor_gc_alloc_region.count() + 4367 _old_gc_alloc_region.count()); 4368 _survivor_gc_alloc_region.release(); 4369 // If we have an old GC alloc region to release, we'll save it in 4370 // _retained_old_gc_alloc_region. If we don't 4371 // _retained_old_gc_alloc_region will become NULL. This is what we 4372 // want either way so no reason to check explicitly for either 4373 // condition. 4374 _retained_old_gc_alloc_region = _old_gc_alloc_region.release(); 4375 4376 if (ResizePLAB) { 4377 _survivor_plab_stats.adjust_desired_plab_sz(no_of_gc_workers); 4378 _old_plab_stats.adjust_desired_plab_sz(no_of_gc_workers); 4379 } 4380 } 4381 4382 void G1CollectedHeap::abandon_gc_alloc_regions() { 4383 assert(_survivor_gc_alloc_region.get() == NULL, "pre-condition"); 4384 assert(_old_gc_alloc_region.get() == NULL, "pre-condition"); 4385 _retained_old_gc_alloc_region = NULL; 4386 } 4387 4388 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) { 4389 _drain_in_progress = false; 4390 set_evac_failure_closure(cl); 4391 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true); 4392 } 4393 4394 void G1CollectedHeap::finalize_for_evac_failure() { 4395 assert(_evac_failure_scan_stack != NULL && 4396 _evac_failure_scan_stack->length() == 0, 4397 "Postcondition"); 4398 assert(!_drain_in_progress, "Postcondition"); 4399 delete _evac_failure_scan_stack; 4400 _evac_failure_scan_stack = NULL; 4401 } 4402 4403 void G1CollectedHeap::remove_self_forwarding_pointers() { 4404 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity"); 4405 4406 double remove_self_forwards_start = os::elapsedTime(); 4407 4408 G1ParRemoveSelfForwardPtrsTask rsfp_task(this); 4409 4410 if (G1CollectedHeap::use_parallel_gc_threads()) { 4411 set_par_threads(); 4412 workers()->run_task(&rsfp_task); 4413 set_par_threads(0); 4414 } else { 4415 rsfp_task.work(0); 4416 } 4417 4418 assert(check_cset_heap_region_claim_values(HeapRegion::ParEvacFailureClaimValue), "sanity"); 4419 4420 // Reset the claim values in the regions in the collection set. 4421 reset_cset_heap_region_claim_values(); 4422 4423 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity"); 4424 4425 // Now restore saved marks, if any. 4426 assert(_objs_with_preserved_marks.size() == 4427 _preserved_marks_of_objs.size(), "Both or none."); 4428 while (!_objs_with_preserved_marks.is_empty()) { 4429 oop obj = _objs_with_preserved_marks.pop(); 4430 markOop m = _preserved_marks_of_objs.pop(); 4431 obj->set_mark(m); 4432 } 4433 _objs_with_preserved_marks.clear(true); 4434 _preserved_marks_of_objs.clear(true); 4435 4436 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0); 4437 } 4438 4439 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) { 4440 _evac_failure_scan_stack->push(obj); 4441 } 4442 4443 void G1CollectedHeap::drain_evac_failure_scan_stack() { 4444 assert(_evac_failure_scan_stack != NULL, "precondition"); 4445 4446 while (_evac_failure_scan_stack->length() > 0) { 4447 oop obj = _evac_failure_scan_stack->pop(); 4448 _evac_failure_closure->set_region(heap_region_containing(obj)); 4449 obj->oop_iterate_backwards(_evac_failure_closure); 4450 } 4451 } 4452 4453 oop 4454 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state, 4455 oop old) { 4456 assert(obj_in_cs(old), 4457 err_msg("obj: "PTR_FORMAT" should still be in the CSet", 4458 (HeapWord*) old)); 4459 markOop m = old->mark(); 4460 oop forward_ptr = old->forward_to_atomic(old); 4461 if (forward_ptr == NULL) { 4462 // Forward-to-self succeeded. 4463 assert(_par_scan_state != NULL, "par scan state"); 4464 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure(); 4465 uint queue_num = _par_scan_state->queue_num(); 4466 4467 _evacuation_failed = true; 4468 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size()); 4469 if (_evac_failure_closure != cl) { 4470 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag); 4471 assert(!_drain_in_progress, 4472 "Should only be true while someone holds the lock."); 4473 // Set the global evac-failure closure to the current thread's. 4474 assert(_evac_failure_closure == NULL, "Or locking has failed."); 4475 set_evac_failure_closure(cl); 4476 // Now do the common part. 4477 handle_evacuation_failure_common(old, m); 4478 // Reset to NULL. 4479 set_evac_failure_closure(NULL); 4480 } else { 4481 // The lock is already held, and this is recursive. 4482 assert(_drain_in_progress, "This should only be the recursive case."); 4483 handle_evacuation_failure_common(old, m); 4484 } 4485 return old; 4486 } else { 4487 // Forward-to-self failed. Either someone else managed to allocate 4488 // space for this object (old != forward_ptr) or they beat us in 4489 // self-forwarding it (old == forward_ptr). 4490 assert(old == forward_ptr || !obj_in_cs(forward_ptr), 4491 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" " 4492 "should not be in the CSet", 4493 (HeapWord*) old, (HeapWord*) forward_ptr)); 4494 return forward_ptr; 4495 } 4496 } 4497 4498 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) { 4499 preserve_mark_if_necessary(old, m); 4500 4501 HeapRegion* r = heap_region_containing(old); 4502 if (!r->evacuation_failed()) { 4503 r->set_evacuation_failed(true); 4504 _hr_printer.evac_failure(r); 4505 } 4506 4507 push_on_evac_failure_scan_stack(old); 4508 4509 if (!_drain_in_progress) { 4510 // prevent recursion in copy_to_survivor_space() 4511 _drain_in_progress = true; 4512 drain_evac_failure_scan_stack(); 4513 _drain_in_progress = false; 4514 } 4515 } 4516 4517 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) { 4518 assert(evacuation_failed(), "Oversaving!"); 4519 // We want to call the "for_promotion_failure" version only in the 4520 // case of a promotion failure. 4521 if (m->must_be_preserved_for_promotion_failure(obj)) { 4522 _objs_with_preserved_marks.push(obj); 4523 _preserved_marks_of_objs.push(m); 4524 } 4525 } 4526 4527 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose, 4528 size_t word_size) { 4529 if (purpose == GCAllocForSurvived) { 4530 HeapWord* result = survivor_attempt_allocation(word_size); 4531 if (result != NULL) { 4532 return result; 4533 } else { 4534 // Let's try to allocate in the old gen in case we can fit the 4535 // object there. 4536 return old_attempt_allocation(word_size); 4537 } 4538 } else { 4539 assert(purpose == GCAllocForTenured, "sanity"); 4540 HeapWord* result = old_attempt_allocation(word_size); 4541 if (result != NULL) { 4542 return result; 4543 } else { 4544 // Let's try to allocate in the survivors in case we can fit the 4545 // object there. 4546 return survivor_attempt_allocation(word_size); 4547 } 4548 } 4549 4550 ShouldNotReachHere(); 4551 // Trying to keep some compilers happy. 4552 return NULL; 4553 } 4554 4555 G1ParGCAllocBuffer::G1ParGCAllocBuffer(size_t gclab_word_size) : 4556 ParGCAllocBuffer(gclab_word_size), _retired(true) { } 4557 4558 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num, ReferenceProcessor* rp) 4559 : _g1h(g1h), 4560 _refs(g1h->task_queue(queue_num)), 4561 _dcq(&g1h->dirty_card_queue_set()), 4562 _ct_bs(g1h->g1_barrier_set()), 4563 _g1_rem(g1h->g1_rem_set()), 4564 _hash_seed(17), _queue_num(queue_num), 4565 _term_attempts(0), 4566 _surviving_alloc_buffer(g1h->desired_plab_sz(GCAllocForSurvived)), 4567 _tenured_alloc_buffer(g1h->desired_plab_sz(GCAllocForTenured)), 4568 _age_table(false), _scanner(g1h, this, rp), 4569 _strong_roots_time(0), _term_time(0), 4570 _alloc_buffer_waste(0), _undo_waste(0) { 4571 // we allocate G1YoungSurvRateNumRegions plus one entries, since 4572 // we "sacrifice" entry 0 to keep track of surviving bytes for 4573 // non-young regions (where the age is -1) 4574 // We also add a few elements at the beginning and at the end in 4575 // an attempt to eliminate cache contention 4576 uint real_length = 1 + _g1h->g1_policy()->young_cset_region_length(); 4577 uint array_length = PADDING_ELEM_NUM + 4578 real_length + 4579 PADDING_ELEM_NUM; 4580 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length, mtGC); 4581 if (_surviving_young_words_base == NULL) 4582 vm_exit_out_of_memory(array_length * sizeof(size_t), OOM_MALLOC_ERROR, 4583 "Not enough space for young surv histo."); 4584 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM; 4585 memset(_surviving_young_words, 0, (size_t) real_length * sizeof(size_t)); 4586 4587 _alloc_buffers[GCAllocForSurvived] = &_surviving_alloc_buffer; 4588 _alloc_buffers[GCAllocForTenured] = &_tenured_alloc_buffer; 4589 4590 _start = os::elapsedTime(); 4591 } 4592 4593 void 4594 G1ParScanThreadState::print_termination_stats_hdr(outputStream* const st) 4595 { 4596 st->print_raw_cr("GC Termination Stats"); 4597 st->print_raw_cr(" elapsed --strong roots-- -------termination-------" 4598 " ------waste (KiB)------"); 4599 st->print_raw_cr("thr ms ms % ms % attempts" 4600 " total alloc undo"); 4601 st->print_raw_cr("--- --------- --------- ------ --------- ------ --------" 4602 " ------- ------- -------"); 4603 } 4604 4605 void 4606 G1ParScanThreadState::print_termination_stats(int i, 4607 outputStream* const st) const 4608 { 4609 const double elapsed_ms = elapsed_time() * 1000.0; 4610 const double s_roots_ms = strong_roots_time() * 1000.0; 4611 const double term_ms = term_time() * 1000.0; 4612 st->print_cr("%3d %9.2f %9.2f %6.2f " 4613 "%9.2f %6.2f " SIZE_FORMAT_W(8) " " 4614 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7), 4615 i, elapsed_ms, s_roots_ms, s_roots_ms * 100 / elapsed_ms, 4616 term_ms, term_ms * 100 / elapsed_ms, term_attempts(), 4617 (alloc_buffer_waste() + undo_waste()) * HeapWordSize / K, 4618 alloc_buffer_waste() * HeapWordSize / K, 4619 undo_waste() * HeapWordSize / K); 4620 } 4621 4622 #ifdef ASSERT 4623 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const { 4624 assert(ref != NULL, "invariant"); 4625 assert(UseCompressedOops, "sanity"); 4626 assert(!has_partial_array_mask(ref), err_msg("ref=" PTR_FORMAT, ref)); 4627 oop p = oopDesc::load_decode_heap_oop(ref); 4628 assert(_g1h->is_in_g1_reserved(p), 4629 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p)); 4630 return true; 4631 } 4632 4633 bool G1ParScanThreadState::verify_ref(oop* ref) const { 4634 assert(ref != NULL, "invariant"); 4635 if (has_partial_array_mask(ref)) { 4636 // Must be in the collection set--it's already been copied. 4637 oop p = clear_partial_array_mask(ref); 4638 assert(_g1h->obj_in_cs(p), 4639 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p)); 4640 } else { 4641 oop p = oopDesc::load_decode_heap_oop(ref); 4642 assert(_g1h->is_in_g1_reserved(p), 4643 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p)); 4644 } 4645 return true; 4646 } 4647 4648 bool G1ParScanThreadState::verify_task(StarTask ref) const { 4649 if (ref.is_narrow()) { 4650 return verify_ref((narrowOop*) ref); 4651 } else { 4652 return verify_ref((oop*) ref); 4653 } 4654 } 4655 #endif // ASSERT 4656 4657 void G1ParScanThreadState::trim_queue() { 4658 assert(_evac_failure_cl != NULL, "not set"); 4659 4660 StarTask ref; 4661 do { 4662 // Drain the overflow stack first, so other threads can steal. 4663 while (refs()->pop_overflow(ref)) { 4664 deal_with_reference(ref); 4665 } 4666 4667 while (refs()->pop_local(ref)) { 4668 deal_with_reference(ref); 4669 } 4670 } while (!refs()->is_empty()); 4671 } 4672 4673 G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1, 4674 G1ParScanThreadState* par_scan_state) : 4675 _g1(g1), _par_scan_state(par_scan_state), 4676 _worker_id(par_scan_state->queue_num()) { } 4677 4678 void G1ParCopyHelper::mark_object(oop obj) { 4679 assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet"); 4680 4681 // We know that the object is not moving so it's safe to read its size. 4682 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id); 4683 } 4684 4685 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) { 4686 assert(from_obj->is_forwarded(), "from obj should be forwarded"); 4687 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee"); 4688 assert(from_obj != to_obj, "should not be self-forwarded"); 4689 4690 assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet"); 4691 assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet"); 4692 4693 // The object might be in the process of being copied by another 4694 // worker so we cannot trust that its to-space image is 4695 // well-formed. So we have to read its size from its from-space 4696 // image which we know should not be changing. 4697 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id); 4698 } 4699 4700 oop G1ParScanThreadState::copy_to_survivor_space(oop const old) { 4701 size_t word_sz = old->size(); 4702 HeapRegion* from_region = _g1h->heap_region_containing_raw(old); 4703 // +1 to make the -1 indexes valid... 4704 int young_index = from_region->young_index_in_cset()+1; 4705 assert( (from_region->is_young() && young_index > 0) || 4706 (!from_region->is_young() && young_index == 0), "invariant" ); 4707 G1CollectorPolicy* g1p = _g1h->g1_policy(); 4708 markOop m = old->mark(); 4709 int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age() 4710 : m->age(); 4711 GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age, 4712 word_sz); 4713 HeapWord* obj_ptr = allocate(alloc_purpose, word_sz); 4714 #ifndef PRODUCT 4715 // Should this evacuation fail? 4716 if (_g1h->evacuation_should_fail()) { 4717 if (obj_ptr != NULL) { 4718 undo_allocation(alloc_purpose, obj_ptr, word_sz); 4719 obj_ptr = NULL; 4720 } 4721 } 4722 #endif // !PRODUCT 4723 4724 if (obj_ptr == NULL) { 4725 // This will either forward-to-self, or detect that someone else has 4726 // installed a forwarding pointer. 4727 return _g1h->handle_evacuation_failure_par(this, old); 4728 } 4729 4730 oop obj = oop(obj_ptr); 4731 4732 // We're going to allocate linearly, so might as well prefetch ahead. 4733 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes); 4734 4735 oop forward_ptr = old->forward_to_atomic(obj); 4736 if (forward_ptr == NULL) { 4737 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz); 4738 4739 // alloc_purpose is just a hint to allocate() above, recheck the type of region 4740 // we actually allocated from and update alloc_purpose accordingly 4741 HeapRegion* to_region = _g1h->heap_region_containing_raw(obj_ptr); 4742 alloc_purpose = to_region->is_young() ? GCAllocForSurvived : GCAllocForTenured; 4743 4744 if (g1p->track_object_age(alloc_purpose)) { 4745 // We could simply do obj->incr_age(). However, this causes a 4746 // performance issue. obj->incr_age() will first check whether 4747 // the object has a displaced mark by checking its mark word; 4748 // getting the mark word from the new location of the object 4749 // stalls. So, given that we already have the mark word and we 4750 // are about to install it anyway, it's better to increase the 4751 // age on the mark word, when the object does not have a 4752 // displaced mark word. We're not expecting many objects to have 4753 // a displaced marked word, so that case is not optimized 4754 // further (it could be...) and we simply call obj->incr_age(). 4755 4756 if (m->has_displaced_mark_helper()) { 4757 // in this case, we have to install the mark word first, 4758 // otherwise obj looks to be forwarded (the old mark word, 4759 // which contains the forward pointer, was copied) 4760 obj->set_mark(m); 4761 obj->incr_age(); 4762 } else { 4763 m = m->incr_age(); 4764 obj->set_mark(m); 4765 } 4766 age_table()->add(obj, word_sz); 4767 } else { 4768 obj->set_mark(m); 4769 } 4770 4771 if (G1StringDedup::is_enabled()) { 4772 G1StringDedup::enqueue_from_evacuation(from_region->is_young(), 4773 to_region->is_young(), 4774 queue_num(), 4775 obj); 4776 } 4777 4778 size_t* surv_young_words = surviving_young_words(); 4779 surv_young_words[young_index] += word_sz; 4780 4781 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) { 4782 // We keep track of the next start index in the length field of 4783 // the to-space object. The actual length can be found in the 4784 // length field of the from-space object. 4785 arrayOop(obj)->set_length(0); 4786 oop* old_p = set_partial_array_mask(old); 4787 push_on_queue(old_p); 4788 } else { 4789 // No point in using the slower heap_region_containing() method, 4790 // given that we know obj is in the heap. 4791 _scanner.set_region(_g1h->heap_region_containing_raw(obj)); 4792 obj->oop_iterate_backwards(&_scanner); 4793 } 4794 } else { 4795 undo_allocation(alloc_purpose, obj_ptr, word_sz); 4796 obj = forward_ptr; 4797 } 4798 return obj; 4799 } 4800 4801 template <class T> 4802 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) { 4803 if (_g1->heap_region_containing_raw(new_obj)->is_young()) { 4804 _scanned_klass->record_modified_oops(); 4805 } 4806 } 4807 4808 template <G1Barrier barrier, bool do_mark_object> 4809 template <class T> 4810 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) { 4811 T heap_oop = oopDesc::load_heap_oop(p); 4812 4813 if (oopDesc::is_null(heap_oop)) { 4814 return; 4815 } 4816 4817 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 4818 4819 assert(_worker_id == _par_scan_state->queue_num(), "sanity"); 4820 4821 if (_g1->in_cset_fast_test(obj)) { 4822 oop forwardee; 4823 if (obj->is_forwarded()) { 4824 forwardee = obj->forwardee(); 4825 } else { 4826 forwardee = _par_scan_state->copy_to_survivor_space(obj); 4827 } 4828 assert(forwardee != NULL, "forwardee should not be NULL"); 4829 oopDesc::encode_store_heap_oop(p, forwardee); 4830 if (do_mark_object && forwardee != obj) { 4831 // If the object is self-forwarded we don't need to explicitly 4832 // mark it, the evacuation failure protocol will do so. 4833 mark_forwarded_object(obj, forwardee); 4834 } 4835 4836 if (barrier == G1BarrierKlass) { 4837 do_klass_barrier(p, forwardee); 4838 } 4839 } else { 4840 // The object is not in collection set. If we're a root scanning 4841 // closure during an initial mark pause (i.e. do_mark_object will 4842 // be true) then attempt to mark the object. 4843 if (do_mark_object) { 4844 mark_object(obj); 4845 } 4846 } 4847 4848 if (barrier == G1BarrierEvac) { 4849 _par_scan_state->update_rs(_from, p, _worker_id); 4850 } 4851 } 4852 4853 template void G1ParCopyClosure<G1BarrierEvac, false>::do_oop_work(oop* p); 4854 template void G1ParCopyClosure<G1BarrierEvac, false>::do_oop_work(narrowOop* p); 4855 4856 class G1ParEvacuateFollowersClosure : public VoidClosure { 4857 protected: 4858 G1CollectedHeap* _g1h; 4859 G1ParScanThreadState* _par_scan_state; 4860 RefToScanQueueSet* _queues; 4861 ParallelTaskTerminator* _terminator; 4862 4863 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 4864 RefToScanQueueSet* queues() { return _queues; } 4865 ParallelTaskTerminator* terminator() { return _terminator; } 4866 4867 public: 4868 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h, 4869 G1ParScanThreadState* par_scan_state, 4870 RefToScanQueueSet* queues, 4871 ParallelTaskTerminator* terminator) 4872 : _g1h(g1h), _par_scan_state(par_scan_state), 4873 _queues(queues), _terminator(terminator) {} 4874 4875 void do_void(); 4876 4877 private: 4878 inline bool offer_termination(); 4879 }; 4880 4881 bool G1ParEvacuateFollowersClosure::offer_termination() { 4882 G1ParScanThreadState* const pss = par_scan_state(); 4883 pss->start_term_time(); 4884 const bool res = terminator()->offer_termination(); 4885 pss->end_term_time(); 4886 return res; 4887 } 4888 4889 void G1ParEvacuateFollowersClosure::do_void() { 4890 StarTask stolen_task; 4891 G1ParScanThreadState* const pss = par_scan_state(); 4892 pss->trim_queue(); 4893 4894 do { 4895 while (queues()->steal(pss->queue_num(), pss->hash_seed(), stolen_task)) { 4896 assert(pss->verify_task(stolen_task), "sanity"); 4897 if (stolen_task.is_narrow()) { 4898 pss->deal_with_reference((narrowOop*) stolen_task); 4899 } else { 4900 pss->deal_with_reference((oop*) stolen_task); 4901 } 4902 4903 // We've just processed a reference and we might have made 4904 // available new entries on the queues. So we have to make sure 4905 // we drain the queues as necessary. 4906 pss->trim_queue(); 4907 } 4908 } while (!offer_termination()); 4909 } 4910 4911 class G1KlassScanClosure : public KlassClosure { 4912 G1ParCopyHelper* _closure; 4913 bool _process_only_dirty; 4914 int _count; 4915 public: 4916 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty) 4917 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {} 4918 void do_klass(Klass* klass) { 4919 // If the klass has not been dirtied we know that there's 4920 // no references into the young gen and we can skip it. 4921 if (!_process_only_dirty || klass->has_modified_oops()) { 4922 // Clean the klass since we're going to scavenge all the metadata. 4923 klass->clear_modified_oops(); 4924 4925 // Tell the closure that this klass is the Klass to scavenge 4926 // and is the one to dirty if oops are left pointing into the young gen. 4927 _closure->set_scanned_klass(klass); 4928 4929 klass->oops_do(_closure); 4930 4931 _closure->set_scanned_klass(NULL); 4932 } 4933 _count++; 4934 } 4935 }; 4936 4937 class G1ParTask : public AbstractGangTask { 4938 protected: 4939 G1CollectedHeap* _g1h; 4940 RefToScanQueueSet *_queues; 4941 ParallelTaskTerminator _terminator; 4942 uint _n_workers; 4943 4944 Mutex _stats_lock; 4945 Mutex* stats_lock() { return &_stats_lock; } 4946 4947 size_t getNCards() { 4948 return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1) 4949 / G1BlockOffsetSharedArray::N_bytes; 4950 } 4951 4952 public: 4953 G1ParTask(G1CollectedHeap* g1h, 4954 RefToScanQueueSet *task_queues) 4955 : AbstractGangTask("G1 collection"), 4956 _g1h(g1h), 4957 _queues(task_queues), 4958 _terminator(0, _queues), 4959 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true) 4960 {} 4961 4962 RefToScanQueueSet* queues() { return _queues; } 4963 4964 RefToScanQueue *work_queue(int i) { 4965 return queues()->queue(i); 4966 } 4967 4968 ParallelTaskTerminator* terminator() { return &_terminator; } 4969 4970 virtual void set_for_termination(int active_workers) { 4971 // This task calls set_n_termination() in par_non_clean_card_iterate_work() 4972 // in the young space (_par_seq_tasks) in the G1 heap 4973 // for SequentialSubTasksDone. 4974 // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap 4975 // both of which need setting by set_n_termination(). 4976 _g1h->SharedHeap::set_n_termination(active_workers); 4977 _g1h->set_n_termination(active_workers); 4978 terminator()->reset_for_reuse(active_workers); 4979 _n_workers = active_workers; 4980 } 4981 4982 void work(uint worker_id) { 4983 if (worker_id >= _n_workers) return; // no work needed this round 4984 4985 double start_time_ms = os::elapsedTime() * 1000.0; 4986 _g1h->g1_policy()->phase_times()->record_gc_worker_start_time(worker_id, start_time_ms); 4987 4988 { 4989 ResourceMark rm; 4990 HandleMark hm; 4991 4992 ReferenceProcessor* rp = _g1h->ref_processor_stw(); 4993 4994 G1ParScanThreadState pss(_g1h, worker_id, rp); 4995 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp); 4996 4997 pss.set_evac_failure_closure(&evac_failure_cl); 4998 4999 G1ParScanExtRootClosure only_scan_root_cl(_g1h, &pss, rp); 5000 G1ParScanMetadataClosure only_scan_metadata_cl(_g1h, &pss, rp); 5001 5002 G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss, rp); 5003 G1ParScanAndMarkMetadataClosure scan_mark_metadata_cl(_g1h, &pss, rp); 5004 5005 bool only_young = _g1h->g1_policy()->gcs_are_young(); 5006 G1KlassScanClosure scan_mark_klasses_cl_s(&scan_mark_metadata_cl, false); 5007 G1KlassScanClosure only_scan_klasses_cl_s(&only_scan_metadata_cl, only_young); 5008 5009 OopClosure* scan_root_cl = &only_scan_root_cl; 5010 G1KlassScanClosure* scan_klasses_cl = &only_scan_klasses_cl_s; 5011 5012 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5013 // We also need to mark copied objects. 5014 scan_root_cl = &scan_mark_root_cl; 5015 scan_klasses_cl = &scan_mark_klasses_cl_s; 5016 } 5017 5018 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss); 5019 5020 // Don't scan the scavengable methods in the code cache as part 5021 // of strong root scanning. The code roots that point into a 5022 // region in the collection set are scanned when we scan the 5023 // region's RSet. 5024 int so = SharedHeap::SO_AllClasses | SharedHeap::SO_Strings; 5025 5026 pss.start_strong_roots(); 5027 _g1h->g1_process_strong_roots(/* is scavenging */ true, 5028 SharedHeap::ScanningOption(so), 5029 scan_root_cl, 5030 &push_heap_rs_cl, 5031 scan_klasses_cl, 5032 worker_id); 5033 pss.end_strong_roots(); 5034 5035 { 5036 double start = os::elapsedTime(); 5037 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator); 5038 evac.do_void(); 5039 double elapsed_ms = (os::elapsedTime()-start)*1000.0; 5040 double term_ms = pss.term_time()*1000.0; 5041 _g1h->g1_policy()->phase_times()->add_obj_copy_time(worker_id, elapsed_ms-term_ms); 5042 _g1h->g1_policy()->phase_times()->record_termination(worker_id, term_ms, pss.term_attempts()); 5043 } 5044 _g1h->g1_policy()->record_thread_age_table(pss.age_table()); 5045 _g1h->update_surviving_young_words(pss.surviving_young_words()+1); 5046 5047 if (ParallelGCVerbose) { 5048 MutexLocker x(stats_lock()); 5049 pss.print_termination_stats(worker_id); 5050 } 5051 5052 assert(pss.refs()->is_empty(), "should be empty"); 5053 5054 // Close the inner scope so that the ResourceMark and HandleMark 5055 // destructors are executed here and are included as part of the 5056 // "GC Worker Time". 5057 } 5058 5059 double end_time_ms = os::elapsedTime() * 1000.0; 5060 _g1h->g1_policy()->phase_times()->record_gc_worker_end_time(worker_id, end_time_ms); 5061 } 5062 }; 5063 5064 // *** Common G1 Evacuation Stuff 5065 5066 // This method is run in a GC worker. 5067 5068 void 5069 G1CollectedHeap:: 5070 g1_process_strong_roots(bool is_scavenging, 5071 ScanningOption so, 5072 OopClosure* scan_non_heap_roots, 5073 OopsInHeapRegionClosure* scan_rs, 5074 G1KlassScanClosure* scan_klasses, 5075 uint worker_i) { 5076 5077 // First scan the strong roots 5078 double ext_roots_start = os::elapsedTime(); 5079 double closure_app_time_sec = 0.0; 5080 5081 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots); 5082 5083 process_strong_roots(false, // no scoping; this is parallel code 5084 so, 5085 &buf_scan_non_heap_roots, 5086 scan_klasses 5087 ); 5088 5089 // Now the CM ref_processor roots. 5090 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) { 5091 // We need to treat the discovered reference lists of the 5092 // concurrent mark ref processor as roots and keep entries 5093 // (which are added by the marking threads) on them live 5094 // until they can be processed at the end of marking. 5095 ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots); 5096 } 5097 5098 // Finish up any enqueued closure apps (attributed as object copy time). 5099 buf_scan_non_heap_roots.done(); 5100 5101 double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds(); 5102 5103 g1_policy()->phase_times()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0); 5104 5105 double ext_root_time_ms = 5106 ((os::elapsedTime() - ext_roots_start) - obj_copy_time_sec) * 1000.0; 5107 5108 g1_policy()->phase_times()->record_ext_root_scan_time(worker_i, ext_root_time_ms); 5109 5110 // During conc marking we have to filter the per-thread SATB buffers 5111 // to make sure we remove any oops into the CSet (which will show up 5112 // as implicitly live). 5113 double satb_filtering_ms = 0.0; 5114 if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers)) { 5115 if (mark_in_progress()) { 5116 double satb_filter_start = os::elapsedTime(); 5117 5118 JavaThread::satb_mark_queue_set().filter_thread_buffers(); 5119 5120 satb_filtering_ms = (os::elapsedTime() - satb_filter_start) * 1000.0; 5121 } 5122 } 5123 g1_policy()->phase_times()->record_satb_filtering_time(worker_i, satb_filtering_ms); 5124 5125 // If this is an initial mark pause, and we're not scanning 5126 // the entire code cache, we need to mark the oops in the 5127 // strong code root lists for the regions that are not in 5128 // the collection set. 5129 // Note all threads participate in this set of root tasks. 5130 double mark_strong_code_roots_ms = 0.0; 5131 if (g1_policy()->during_initial_mark_pause() && !(so & SO_AllCodeCache)) { 5132 double mark_strong_roots_start = os::elapsedTime(); 5133 mark_strong_code_roots(worker_i); 5134 mark_strong_code_roots_ms = (os::elapsedTime() - mark_strong_roots_start) * 1000.0; 5135 } 5136 g1_policy()->phase_times()->record_strong_code_root_mark_time(worker_i, mark_strong_code_roots_ms); 5137 5138 // Now scan the complement of the collection set. 5139 CodeBlobToOopClosure eager_scan_code_roots(scan_non_heap_roots, true /* do_marking */); 5140 g1_rem_set()->oops_into_collection_set_do(scan_rs, &eager_scan_code_roots, worker_i); 5141 5142 _process_strong_tasks->all_tasks_completed(); 5143 } 5144 5145 class G1StringSymbolTableUnlinkTask : public AbstractGangTask { 5146 private: 5147 BoolObjectClosure* _is_alive; 5148 int _initial_string_table_size; 5149 int _initial_symbol_table_size; 5150 5151 bool _process_strings; 5152 int _strings_processed; 5153 int _strings_removed; 5154 5155 bool _process_symbols; 5156 int _symbols_processed; 5157 int _symbols_removed; 5158 5159 bool _do_in_parallel; 5160 public: 5161 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) : 5162 AbstractGangTask("Par String/Symbol table unlink"), _is_alive(is_alive), 5163 _do_in_parallel(G1CollectedHeap::use_parallel_gc_threads()), 5164 _process_strings(process_strings), _strings_processed(0), _strings_removed(0), 5165 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) { 5166 5167 _initial_string_table_size = StringTable::the_table()->table_size(); 5168 _initial_symbol_table_size = SymbolTable::the_table()->table_size(); 5169 if (process_strings) { 5170 StringTable::clear_parallel_claimed_index(); 5171 } 5172 if (process_symbols) { 5173 SymbolTable::clear_parallel_claimed_index(); 5174 } 5175 } 5176 5177 ~G1StringSymbolTableUnlinkTask() { 5178 guarantee(!_process_strings || !_do_in_parallel || StringTable::parallel_claimed_index() >= _initial_string_table_size, 5179 err_msg("claim value %d after unlink less than initial string table size %d", 5180 StringTable::parallel_claimed_index(), _initial_string_table_size)); 5181 guarantee(!_process_symbols || !_do_in_parallel || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size, 5182 err_msg("claim value %d after unlink less than initial symbol table size %d", 5183 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size)); 5184 } 5185 5186 void work(uint worker_id) { 5187 if (_do_in_parallel) { 5188 int strings_processed = 0; 5189 int strings_removed = 0; 5190 int symbols_processed = 0; 5191 int symbols_removed = 0; 5192 if (_process_strings) { 5193 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed); 5194 Atomic::add(strings_processed, &_strings_processed); 5195 Atomic::add(strings_removed, &_strings_removed); 5196 } 5197 if (_process_symbols) { 5198 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed); 5199 Atomic::add(symbols_processed, &_symbols_processed); 5200 Atomic::add(symbols_removed, &_symbols_removed); 5201 } 5202 } else { 5203 if (_process_strings) { 5204 StringTable::unlink(_is_alive, &_strings_processed, &_strings_removed); 5205 } 5206 if (_process_symbols) { 5207 SymbolTable::unlink(&_symbols_processed, &_symbols_removed); 5208 } 5209 } 5210 } 5211 5212 size_t strings_processed() const { return (size_t)_strings_processed; } 5213 size_t strings_removed() const { return (size_t)_strings_removed; } 5214 5215 size_t symbols_processed() const { return (size_t)_symbols_processed; } 5216 size_t symbols_removed() const { return (size_t)_symbols_removed; } 5217 }; 5218 5219 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive, 5220 bool process_strings, bool process_symbols) { 5221 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ? 5222 _g1h->workers()->active_workers() : 1); 5223 5224 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols); 5225 if (G1CollectedHeap::use_parallel_gc_threads()) { 5226 set_par_threads(n_workers); 5227 workers()->run_task(&g1_unlink_task); 5228 set_par_threads(0); 5229 } else { 5230 g1_unlink_task.work(0); 5231 } 5232 if (G1TraceStringSymbolTableScrubbing) { 5233 gclog_or_tty->print_cr("Cleaned string and symbol table, " 5234 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, " 5235 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed", 5236 g1_unlink_task.strings_processed(), g1_unlink_task.strings_removed(), 5237 g1_unlink_task.symbols_processed(), g1_unlink_task.symbols_removed()); 5238 } 5239 5240 if (G1StringDedup::is_enabled()) { 5241 G1StringDedup::unlink(is_alive); 5242 } 5243 } 5244 5245 class G1RedirtyLoggedCardsTask : public AbstractGangTask { 5246 private: 5247 DirtyCardQueueSet* _queue; 5248 public: 5249 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { } 5250 5251 virtual void work(uint worker_id) { 5252 double start_time = os::elapsedTime(); 5253 5254 RedirtyLoggedCardTableEntryClosure cl; 5255 if (G1CollectedHeap::heap()->use_parallel_gc_threads()) { 5256 _queue->par_apply_closure_to_all_completed_buffers(&cl); 5257 } else { 5258 _queue->apply_closure_to_all_completed_buffers(&cl); 5259 } 5260 5261 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times(); 5262 timer->record_redirty_logged_cards_time_ms(worker_id, (os::elapsedTime() - start_time) * 1000.0); 5263 timer->record_redirty_logged_cards_processed_cards(worker_id, cl.num_processed()); 5264 } 5265 }; 5266 5267 void G1CollectedHeap::redirty_logged_cards() { 5268 guarantee(G1DeferredRSUpdate, "Must only be called when using deferred RS updates."); 5269 double redirty_logged_cards_start = os::elapsedTime(); 5270 5271 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ? 5272 _g1h->workers()->active_workers() : 1); 5273 5274 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set()); 5275 dirty_card_queue_set().reset_for_par_iteration(); 5276 if (use_parallel_gc_threads()) { 5277 set_par_threads(n_workers); 5278 workers()->run_task(&redirty_task); 5279 set_par_threads(0); 5280 } else { 5281 redirty_task.work(0); 5282 } 5283 5284 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set(); 5285 dcq.merge_bufferlists(&dirty_card_queue_set()); 5286 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed"); 5287 5288 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0); 5289 } 5290 5291 // Weak Reference Processing support 5292 5293 // An always "is_alive" closure that is used to preserve referents. 5294 // If the object is non-null then it's alive. Used in the preservation 5295 // of referent objects that are pointed to by reference objects 5296 // discovered by the CM ref processor. 5297 class G1AlwaysAliveClosure: public BoolObjectClosure { 5298 G1CollectedHeap* _g1; 5299 public: 5300 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 5301 bool do_object_b(oop p) { 5302 if (p != NULL) { 5303 return true; 5304 } 5305 return false; 5306 } 5307 }; 5308 5309 bool G1STWIsAliveClosure::do_object_b(oop p) { 5310 // An object is reachable if it is outside the collection set, 5311 // or is inside and copied. 5312 return !_g1->obj_in_cs(p) || p->is_forwarded(); 5313 } 5314 5315 // Non Copying Keep Alive closure 5316 class G1KeepAliveClosure: public OopClosure { 5317 G1CollectedHeap* _g1; 5318 public: 5319 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 5320 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } 5321 void do_oop( oop* p) { 5322 oop obj = *p; 5323 5324 if (_g1->obj_in_cs(obj)) { 5325 assert( obj->is_forwarded(), "invariant" ); 5326 *p = obj->forwardee(); 5327 } 5328 } 5329 }; 5330 5331 // Copying Keep Alive closure - can be called from both 5332 // serial and parallel code as long as different worker 5333 // threads utilize different G1ParScanThreadState instances 5334 // and different queues. 5335 5336 class G1CopyingKeepAliveClosure: public OopClosure { 5337 G1CollectedHeap* _g1h; 5338 OopClosure* _copy_non_heap_obj_cl; 5339 OopsInHeapRegionClosure* _copy_metadata_obj_cl; 5340 G1ParScanThreadState* _par_scan_state; 5341 5342 public: 5343 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, 5344 OopClosure* non_heap_obj_cl, 5345 OopsInHeapRegionClosure* metadata_obj_cl, 5346 G1ParScanThreadState* pss): 5347 _g1h(g1h), 5348 _copy_non_heap_obj_cl(non_heap_obj_cl), 5349 _copy_metadata_obj_cl(metadata_obj_cl), 5350 _par_scan_state(pss) 5351 {} 5352 5353 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 5354 virtual void do_oop( oop* p) { do_oop_work(p); } 5355 5356 template <class T> void do_oop_work(T* p) { 5357 oop obj = oopDesc::load_decode_heap_oop(p); 5358 5359 if (_g1h->obj_in_cs(obj)) { 5360 // If the referent object has been forwarded (either copied 5361 // to a new location or to itself in the event of an 5362 // evacuation failure) then we need to update the reference 5363 // field and, if both reference and referent are in the G1 5364 // heap, update the RSet for the referent. 5365 // 5366 // If the referent has not been forwarded then we have to keep 5367 // it alive by policy. Therefore we have copy the referent. 5368 // 5369 // If the reference field is in the G1 heap then we can push 5370 // on the PSS queue. When the queue is drained (after each 5371 // phase of reference processing) the object and it's followers 5372 // will be copied, the reference field set to point to the 5373 // new location, and the RSet updated. Otherwise we need to 5374 // use the the non-heap or metadata closures directly to copy 5375 // the referent object and update the pointer, while avoiding 5376 // updating the RSet. 5377 5378 if (_g1h->is_in_g1_reserved(p)) { 5379 _par_scan_state->push_on_queue(p); 5380 } else { 5381 assert(!ClassLoaderDataGraph::contains((address)p), 5382 err_msg("Otherwise need to call _copy_metadata_obj_cl->do_oop(p) " 5383 PTR_FORMAT, p)); 5384 _copy_non_heap_obj_cl->do_oop(p); 5385 } 5386 } 5387 } 5388 }; 5389 5390 // Serial drain queue closure. Called as the 'complete_gc' 5391 // closure for each discovered list in some of the 5392 // reference processing phases. 5393 5394 class G1STWDrainQueueClosure: public VoidClosure { 5395 protected: 5396 G1CollectedHeap* _g1h; 5397 G1ParScanThreadState* _par_scan_state; 5398 5399 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 5400 5401 public: 5402 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : 5403 _g1h(g1h), 5404 _par_scan_state(pss) 5405 { } 5406 5407 void do_void() { 5408 G1ParScanThreadState* const pss = par_scan_state(); 5409 pss->trim_queue(); 5410 } 5411 }; 5412 5413 // Parallel Reference Processing closures 5414 5415 // Implementation of AbstractRefProcTaskExecutor for parallel reference 5416 // processing during G1 evacuation pauses. 5417 5418 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 5419 private: 5420 G1CollectedHeap* _g1h; 5421 RefToScanQueueSet* _queues; 5422 FlexibleWorkGang* _workers; 5423 int _active_workers; 5424 5425 public: 5426 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, 5427 FlexibleWorkGang* workers, 5428 RefToScanQueueSet *task_queues, 5429 int n_workers) : 5430 _g1h(g1h), 5431 _queues(task_queues), 5432 _workers(workers), 5433 _active_workers(n_workers) 5434 { 5435 assert(n_workers > 0, "shouldn't call this otherwise"); 5436 } 5437 5438 // Executes the given task using concurrent marking worker threads. 5439 virtual void execute(ProcessTask& task); 5440 virtual void execute(EnqueueTask& task); 5441 }; 5442 5443 // Gang task for possibly parallel reference processing 5444 5445 class G1STWRefProcTaskProxy: public AbstractGangTask { 5446 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 5447 ProcessTask& _proc_task; 5448 G1CollectedHeap* _g1h; 5449 RefToScanQueueSet *_task_queues; 5450 ParallelTaskTerminator* _terminator; 5451 5452 public: 5453 G1STWRefProcTaskProxy(ProcessTask& proc_task, 5454 G1CollectedHeap* g1h, 5455 RefToScanQueueSet *task_queues, 5456 ParallelTaskTerminator* terminator) : 5457 AbstractGangTask("Process reference objects in parallel"), 5458 _proc_task(proc_task), 5459 _g1h(g1h), 5460 _task_queues(task_queues), 5461 _terminator(terminator) 5462 {} 5463 5464 virtual void work(uint worker_id) { 5465 // The reference processing task executed by a single worker. 5466 ResourceMark rm; 5467 HandleMark hm; 5468 5469 G1STWIsAliveClosure is_alive(_g1h); 5470 5471 G1ParScanThreadState pss(_g1h, worker_id, NULL); 5472 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL); 5473 5474 pss.set_evac_failure_closure(&evac_failure_cl); 5475 5476 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL); 5477 G1ParScanMetadataClosure only_copy_metadata_cl(_g1h, &pss, NULL); 5478 5479 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL); 5480 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL); 5481 5482 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5483 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl; 5484 5485 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5486 // We also need to mark copied objects. 5487 copy_non_heap_cl = ©_mark_non_heap_cl; 5488 copy_metadata_cl = ©_mark_metadata_cl; 5489 } 5490 5491 // Keep alive closure. 5492 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss); 5493 5494 // Complete GC closure 5495 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator); 5496 5497 // Call the reference processing task's work routine. 5498 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); 5499 5500 // Note we cannot assert that the refs array is empty here as not all 5501 // of the processing tasks (specifically phase2 - pp2_work) execute 5502 // the complete_gc closure (which ordinarily would drain the queue) so 5503 // the queue may not be empty. 5504 } 5505 }; 5506 5507 // Driver routine for parallel reference processing. 5508 // Creates an instance of the ref processing gang 5509 // task and has the worker threads execute it. 5510 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) { 5511 assert(_workers != NULL, "Need parallel worker threads."); 5512 5513 ParallelTaskTerminator terminator(_active_workers, _queues); 5514 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator); 5515 5516 _g1h->set_par_threads(_active_workers); 5517 _workers->run_task(&proc_task_proxy); 5518 _g1h->set_par_threads(0); 5519 } 5520 5521 // Gang task for parallel reference enqueueing. 5522 5523 class G1STWRefEnqueueTaskProxy: public AbstractGangTask { 5524 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; 5525 EnqueueTask& _enq_task; 5526 5527 public: 5528 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) : 5529 AbstractGangTask("Enqueue reference objects in parallel"), 5530 _enq_task(enq_task) 5531 { } 5532 5533 virtual void work(uint worker_id) { 5534 _enq_task.work(worker_id); 5535 } 5536 }; 5537 5538 // Driver routine for parallel reference enqueueing. 5539 // Creates an instance of the ref enqueueing gang 5540 // task and has the worker threads execute it. 5541 5542 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) { 5543 assert(_workers != NULL, "Need parallel worker threads."); 5544 5545 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task); 5546 5547 _g1h->set_par_threads(_active_workers); 5548 _workers->run_task(&enq_task_proxy); 5549 _g1h->set_par_threads(0); 5550 } 5551 5552 // End of weak reference support closures 5553 5554 // Abstract task used to preserve (i.e. copy) any referent objects 5555 // that are in the collection set and are pointed to by reference 5556 // objects discovered by the CM ref processor. 5557 5558 class G1ParPreserveCMReferentsTask: public AbstractGangTask { 5559 protected: 5560 G1CollectedHeap* _g1h; 5561 RefToScanQueueSet *_queues; 5562 ParallelTaskTerminator _terminator; 5563 uint _n_workers; 5564 5565 public: 5566 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) : 5567 AbstractGangTask("ParPreserveCMReferents"), 5568 _g1h(g1h), 5569 _queues(task_queues), 5570 _terminator(workers, _queues), 5571 _n_workers(workers) 5572 { } 5573 5574 void work(uint worker_id) { 5575 ResourceMark rm; 5576 HandleMark hm; 5577 5578 G1ParScanThreadState pss(_g1h, worker_id, NULL); 5579 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL); 5580 5581 pss.set_evac_failure_closure(&evac_failure_cl); 5582 5583 assert(pss.refs()->is_empty(), "both queue and overflow should be empty"); 5584 5585 5586 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL); 5587 G1ParScanMetadataClosure only_copy_metadata_cl(_g1h, &pss, NULL); 5588 5589 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL); 5590 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL); 5591 5592 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5593 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl; 5594 5595 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5596 // We also need to mark copied objects. 5597 copy_non_heap_cl = ©_mark_non_heap_cl; 5598 copy_metadata_cl = ©_mark_metadata_cl; 5599 } 5600 5601 // Is alive closure 5602 G1AlwaysAliveClosure always_alive(_g1h); 5603 5604 // Copying keep alive closure. Applied to referent objects that need 5605 // to be copied. 5606 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss); 5607 5608 ReferenceProcessor* rp = _g1h->ref_processor_cm(); 5609 5610 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q(); 5611 uint stride = MIN2(MAX2(_n_workers, 1U), limit); 5612 5613 // limit is set using max_num_q() - which was set using ParallelGCThreads. 5614 // So this must be true - but assert just in case someone decides to 5615 // change the worker ids. 5616 assert(0 <= worker_id && worker_id < limit, "sanity"); 5617 assert(!rp->discovery_is_atomic(), "check this code"); 5618 5619 // Select discovered lists [i, i+stride, i+2*stride,...,limit) 5620 for (uint idx = worker_id; idx < limit; idx += stride) { 5621 DiscoveredList& ref_list = rp->discovered_refs()[idx]; 5622 5623 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive); 5624 while (iter.has_next()) { 5625 // Since discovery is not atomic for the CM ref processor, we 5626 // can see some null referent objects. 5627 iter.load_ptrs(DEBUG_ONLY(true)); 5628 oop ref = iter.obj(); 5629 5630 // This will filter nulls. 5631 if (iter.is_referent_alive()) { 5632 iter.make_referent_alive(); 5633 } 5634 iter.move_to_next(); 5635 } 5636 } 5637 5638 // Drain the queue - which may cause stealing 5639 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator); 5640 drain_queue.do_void(); 5641 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure 5642 assert(pss.refs()->is_empty(), "should be"); 5643 } 5644 }; 5645 5646 // Weak Reference processing during an evacuation pause (part 1). 5647 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) { 5648 double ref_proc_start = os::elapsedTime(); 5649 5650 ReferenceProcessor* rp = _ref_processor_stw; 5651 assert(rp->discovery_enabled(), "should have been enabled"); 5652 5653 // Any reference objects, in the collection set, that were 'discovered' 5654 // by the CM ref processor should have already been copied (either by 5655 // applying the external root copy closure to the discovered lists, or 5656 // by following an RSet entry). 5657 // 5658 // But some of the referents, that are in the collection set, that these 5659 // reference objects point to may not have been copied: the STW ref 5660 // processor would have seen that the reference object had already 5661 // been 'discovered' and would have skipped discovering the reference, 5662 // but would not have treated the reference object as a regular oop. 5663 // As a result the copy closure would not have been applied to the 5664 // referent object. 5665 // 5666 // We need to explicitly copy these referent objects - the references 5667 // will be processed at the end of remarking. 5668 // 5669 // We also need to do this copying before we process the reference 5670 // objects discovered by the STW ref processor in case one of these 5671 // referents points to another object which is also referenced by an 5672 // object discovered by the STW ref processor. 5673 5674 assert(!G1CollectedHeap::use_parallel_gc_threads() || 5675 no_of_gc_workers == workers()->active_workers(), 5676 "Need to reset active GC workers"); 5677 5678 set_par_threads(no_of_gc_workers); 5679 G1ParPreserveCMReferentsTask keep_cm_referents(this, 5680 no_of_gc_workers, 5681 _task_queues); 5682 5683 if (G1CollectedHeap::use_parallel_gc_threads()) { 5684 workers()->run_task(&keep_cm_referents); 5685 } else { 5686 keep_cm_referents.work(0); 5687 } 5688 5689 set_par_threads(0); 5690 5691 // Closure to test whether a referent is alive. 5692 G1STWIsAliveClosure is_alive(this); 5693 5694 // Even when parallel reference processing is enabled, the processing 5695 // of JNI refs is serial and performed serially by the current thread 5696 // rather than by a worker. The following PSS will be used for processing 5697 // JNI refs. 5698 5699 // Use only a single queue for this PSS. 5700 G1ParScanThreadState pss(this, 0, NULL); 5701 5702 // We do not embed a reference processor in the copying/scanning 5703 // closures while we're actually processing the discovered 5704 // reference objects. 5705 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL); 5706 5707 pss.set_evac_failure_closure(&evac_failure_cl); 5708 5709 assert(pss.refs()->is_empty(), "pre-condition"); 5710 5711 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL); 5712 G1ParScanMetadataClosure only_copy_metadata_cl(this, &pss, NULL); 5713 5714 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL); 5715 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(this, &pss, NULL); 5716 5717 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5718 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl; 5719 5720 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5721 // We also need to mark copied objects. 5722 copy_non_heap_cl = ©_mark_non_heap_cl; 5723 copy_metadata_cl = ©_mark_metadata_cl; 5724 } 5725 5726 // Keep alive closure. 5727 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, copy_metadata_cl, &pss); 5728 5729 // Serial Complete GC closure 5730 G1STWDrainQueueClosure drain_queue(this, &pss); 5731 5732 // Setup the soft refs policy... 5733 rp->setup_policy(false); 5734 5735 ReferenceProcessorStats stats; 5736 if (!rp->processing_is_mt()) { 5737 // Serial reference processing... 5738 stats = rp->process_discovered_references(&is_alive, 5739 &keep_alive, 5740 &drain_queue, 5741 NULL, 5742 _gc_timer_stw); 5743 } else { 5744 // Parallel reference processing 5745 assert(rp->num_q() == no_of_gc_workers, "sanity"); 5746 assert(no_of_gc_workers <= rp->max_num_q(), "sanity"); 5747 5748 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers); 5749 stats = rp->process_discovered_references(&is_alive, 5750 &keep_alive, 5751 &drain_queue, 5752 &par_task_executor, 5753 _gc_timer_stw); 5754 } 5755 5756 _gc_tracer_stw->report_gc_reference_stats(stats); 5757 5758 // We have completed copying any necessary live referent objects. 5759 assert(pss.refs()->is_empty(), "both queue and overflow should be empty"); 5760 5761 double ref_proc_time = os::elapsedTime() - ref_proc_start; 5762 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 5763 } 5764 5765 // Weak Reference processing during an evacuation pause (part 2). 5766 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) { 5767 double ref_enq_start = os::elapsedTime(); 5768 5769 ReferenceProcessor* rp = _ref_processor_stw; 5770 assert(!rp->discovery_enabled(), "should have been disabled as part of processing"); 5771 5772 // Now enqueue any remaining on the discovered lists on to 5773 // the pending list. 5774 if (!rp->processing_is_mt()) { 5775 // Serial reference processing... 5776 rp->enqueue_discovered_references(); 5777 } else { 5778 // Parallel reference enqueueing 5779 5780 assert(no_of_gc_workers == workers()->active_workers(), 5781 "Need to reset active workers"); 5782 assert(rp->num_q() == no_of_gc_workers, "sanity"); 5783 assert(no_of_gc_workers <= rp->max_num_q(), "sanity"); 5784 5785 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers); 5786 rp->enqueue_discovered_references(&par_task_executor); 5787 } 5788 5789 rp->verify_no_references_recorded(); 5790 assert(!rp->discovery_enabled(), "should have been disabled"); 5791 5792 // FIXME 5793 // CM's reference processing also cleans up the string and symbol tables. 5794 // Should we do that here also? We could, but it is a serial operation 5795 // and could significantly increase the pause time. 5796 5797 double ref_enq_time = os::elapsedTime() - ref_enq_start; 5798 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0); 5799 } 5800 5801 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) { 5802 _expand_heap_after_alloc_failure = true; 5803 _evacuation_failed = false; 5804 5805 // Should G1EvacuationFailureALot be in effect for this GC? 5806 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) 5807 5808 g1_rem_set()->prepare_for_oops_into_collection_set_do(); 5809 5810 // Disable the hot card cache. 5811 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 5812 hot_card_cache->reset_hot_cache_claimed_index(); 5813 hot_card_cache->set_use_cache(false); 5814 5815 uint n_workers; 5816 if (G1CollectedHeap::use_parallel_gc_threads()) { 5817 n_workers = 5818 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 5819 workers()->active_workers(), 5820 Threads::number_of_non_daemon_threads()); 5821 assert(UseDynamicNumberOfGCThreads || 5822 n_workers == workers()->total_workers(), 5823 "If not dynamic should be using all the workers"); 5824 workers()->set_active_workers(n_workers); 5825 set_par_threads(n_workers); 5826 } else { 5827 assert(n_par_threads() == 0, 5828 "Should be the original non-parallel value"); 5829 n_workers = 1; 5830 } 5831 5832 G1ParTask g1_par_task(this, _task_queues); 5833 5834 init_for_evac_failure(NULL); 5835 5836 rem_set()->prepare_for_younger_refs_iterate(true); 5837 5838 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty"); 5839 double start_par_time_sec = os::elapsedTime(); 5840 double end_par_time_sec; 5841 5842 { 5843 StrongRootsScope srs(this); 5844 5845 if (G1CollectedHeap::use_parallel_gc_threads()) { 5846 // The individual threads will set their evac-failure closures. 5847 if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr(); 5848 // These tasks use ShareHeap::_process_strong_tasks 5849 assert(UseDynamicNumberOfGCThreads || 5850 workers()->active_workers() == workers()->total_workers(), 5851 "If not dynamic should be using all the workers"); 5852 workers()->run_task(&g1_par_task); 5853 } else { 5854 g1_par_task.set_for_termination(n_workers); 5855 g1_par_task.work(0); 5856 } 5857 end_par_time_sec = os::elapsedTime(); 5858 5859 // Closing the inner scope will execute the destructor 5860 // for the StrongRootsScope object. We record the current 5861 // elapsed time before closing the scope so that time 5862 // taken for the SRS destructor is NOT included in the 5863 // reported parallel time. 5864 } 5865 5866 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0; 5867 g1_policy()->phase_times()->record_par_time(par_time_ms); 5868 5869 double code_root_fixup_time_ms = 5870 (os::elapsedTime() - end_par_time_sec) * 1000.0; 5871 g1_policy()->phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms); 5872 5873 set_par_threads(0); 5874 5875 // Process any discovered reference objects - we have 5876 // to do this _before_ we retire the GC alloc regions 5877 // as we may have to copy some 'reachable' referent 5878 // objects (and their reachable sub-graphs) that were 5879 // not copied during the pause. 5880 process_discovered_references(n_workers); 5881 5882 // Weak root processing. 5883 { 5884 G1STWIsAliveClosure is_alive(this); 5885 G1KeepAliveClosure keep_alive(this); 5886 JNIHandles::weak_oops_do(&is_alive, &keep_alive); 5887 if (G1StringDedup::is_enabled()) { 5888 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive); 5889 } 5890 } 5891 5892 release_gc_alloc_regions(n_workers, evacuation_info); 5893 g1_rem_set()->cleanup_after_oops_into_collection_set_do(); 5894 5895 // Reset and re-enable the hot card cache. 5896 // Note the counts for the cards in the regions in the 5897 // collection set are reset when the collection set is freed. 5898 hot_card_cache->reset_hot_cache(); 5899 hot_card_cache->set_use_cache(true); 5900 5901 // Migrate the strong code roots attached to each region in 5902 // the collection set. Ideally we would like to do this 5903 // after we have finished the scanning/evacuation of the 5904 // strong code roots for a particular heap region. 5905 migrate_strong_code_roots(); 5906 5907 purge_code_root_memory(); 5908 5909 if (g1_policy()->during_initial_mark_pause()) { 5910 // Reset the claim values set during marking the strong code roots 5911 reset_heap_region_claim_values(); 5912 } 5913 5914 finalize_for_evac_failure(); 5915 5916 if (evacuation_failed()) { 5917 remove_self_forwarding_pointers(); 5918 5919 // Reset the G1EvacuationFailureALot counters and flags 5920 // Note: the values are reset only when an actual 5921 // evacuation failure occurs. 5922 NOT_PRODUCT(reset_evacuation_should_fail();) 5923 } 5924 5925 // Enqueue any remaining references remaining on the STW 5926 // reference processor's discovered lists. We need to do 5927 // this after the card table is cleaned (and verified) as 5928 // the act of enqueueing entries on to the pending list 5929 // will log these updates (and dirty their associated 5930 // cards). We need these updates logged to update any 5931 // RSets. 5932 enqueue_discovered_references(n_workers); 5933 5934 if (G1DeferredRSUpdate) { 5935 redirty_logged_cards(); 5936 } 5937 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 5938 } 5939 5940 void G1CollectedHeap::free_region(HeapRegion* hr, 5941 FreeRegionList* free_list, 5942 bool par, 5943 bool locked) { 5944 assert(!hr->isHumongous(), "this is only for non-humongous regions"); 5945 assert(!hr->is_empty(), "the region should not be empty"); 5946 assert(free_list != NULL, "pre-condition"); 5947 5948 // Clear the card counts for this region. 5949 // Note: we only need to do this if the region is not young 5950 // (since we don't refine cards in young regions). 5951 if (!hr->is_young()) { 5952 _cg1r->hot_card_cache()->reset_card_counts(hr); 5953 } 5954 hr->hr_clear(par, true /* clear_space */, locked /* locked */); 5955 free_list->add_ordered(hr); 5956 } 5957 5958 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 5959 FreeRegionList* free_list, 5960 bool par) { 5961 assert(hr->startsHumongous(), "this is only for starts humongous regions"); 5962 assert(free_list != NULL, "pre-condition"); 5963 5964 size_t hr_capacity = hr->capacity(); 5965 // We need to read this before we make the region non-humongous, 5966 // otherwise the information will be gone. 5967 uint last_index = hr->last_hc_index(); 5968 hr->set_notHumongous(); 5969 free_region(hr, free_list, par); 5970 5971 uint i = hr->hrs_index() + 1; 5972 while (i < last_index) { 5973 HeapRegion* curr_hr = region_at(i); 5974 assert(curr_hr->continuesHumongous(), "invariant"); 5975 curr_hr->set_notHumongous(); 5976 free_region(curr_hr, free_list, par); 5977 i += 1; 5978 } 5979 } 5980 5981 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed, 5982 const HeapRegionSetCount& humongous_regions_removed) { 5983 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) { 5984 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 5985 _old_set.bulk_remove(old_regions_removed); 5986 _humongous_set.bulk_remove(humongous_regions_removed); 5987 } 5988 5989 } 5990 5991 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) { 5992 assert(list != NULL, "list can't be null"); 5993 if (!list->is_empty()) { 5994 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag); 5995 _free_list.add_ordered(list); 5996 } 5997 } 5998 5999 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) { 6000 assert(_summary_bytes_used >= bytes, 6001 err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" should be >= bytes: "SIZE_FORMAT, 6002 _summary_bytes_used, bytes)); 6003 _summary_bytes_used -= bytes; 6004 } 6005 6006 class G1ParCleanupCTTask : public AbstractGangTask { 6007 G1SATBCardTableModRefBS* _ct_bs; 6008 G1CollectedHeap* _g1h; 6009 HeapRegion* volatile _su_head; 6010 public: 6011 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs, 6012 G1CollectedHeap* g1h) : 6013 AbstractGangTask("G1 Par Cleanup CT Task"), 6014 _ct_bs(ct_bs), _g1h(g1h) { } 6015 6016 void work(uint worker_id) { 6017 HeapRegion* r; 6018 while (r = _g1h->pop_dirty_cards_region()) { 6019 clear_cards(r); 6020 } 6021 } 6022 6023 void clear_cards(HeapRegion* r) { 6024 // Cards of the survivors should have already been dirtied. 6025 if (!r->is_survivor()) { 6026 _ct_bs->clear(MemRegion(r->bottom(), r->end())); 6027 } 6028 } 6029 }; 6030 6031 #ifndef PRODUCT 6032 class G1VerifyCardTableCleanup: public HeapRegionClosure { 6033 G1CollectedHeap* _g1h; 6034 G1SATBCardTableModRefBS* _ct_bs; 6035 public: 6036 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs) 6037 : _g1h(g1h), _ct_bs(ct_bs) { } 6038 virtual bool doHeapRegion(HeapRegion* r) { 6039 if (r->is_survivor()) { 6040 _g1h->verify_dirty_region(r); 6041 } else { 6042 _g1h->verify_not_dirty_region(r); 6043 } 6044 return false; 6045 } 6046 }; 6047 6048 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) { 6049 // All of the region should be clean. 6050 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 6051 MemRegion mr(hr->bottom(), hr->end()); 6052 ct_bs->verify_not_dirty_region(mr); 6053 } 6054 6055 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) { 6056 // We cannot guarantee that [bottom(),end()] is dirty. Threads 6057 // dirty allocated blocks as they allocate them. The thread that 6058 // retires each region and replaces it with a new one will do a 6059 // maximal allocation to fill in [pre_dummy_top(),end()] but will 6060 // not dirty that area (one less thing to have to do while holding 6061 // a lock). So we can only verify that [bottom(),pre_dummy_top()] 6062 // is dirty. 6063 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 6064 MemRegion mr(hr->bottom(), hr->pre_dummy_top()); 6065 if (hr->is_young()) { 6066 ct_bs->verify_g1_young_region(mr); 6067 } else { 6068 ct_bs->verify_dirty_region(mr); 6069 } 6070 } 6071 6072 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) { 6073 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 6074 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) { 6075 verify_dirty_region(hr); 6076 } 6077 } 6078 6079 void G1CollectedHeap::verify_dirty_young_regions() { 6080 verify_dirty_young_list(_young_list->first_region()); 6081 } 6082 #endif 6083 6084 void G1CollectedHeap::cleanUpCardTable() { 6085 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 6086 double start = os::elapsedTime(); 6087 6088 { 6089 // Iterate over the dirty cards region list. 6090 G1ParCleanupCTTask cleanup_task(ct_bs, this); 6091 6092 if (G1CollectedHeap::use_parallel_gc_threads()) { 6093 set_par_threads(); 6094 workers()->run_task(&cleanup_task); 6095 set_par_threads(0); 6096 } else { 6097 while (_dirty_cards_region_list) { 6098 HeapRegion* r = _dirty_cards_region_list; 6099 cleanup_task.clear_cards(r); 6100 _dirty_cards_region_list = r->get_next_dirty_cards_region(); 6101 if (_dirty_cards_region_list == r) { 6102 // The last region. 6103 _dirty_cards_region_list = NULL; 6104 } 6105 r->set_next_dirty_cards_region(NULL); 6106 } 6107 } 6108 #ifndef PRODUCT 6109 if (G1VerifyCTCleanup || VerifyAfterGC) { 6110 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs); 6111 heap_region_iterate(&cleanup_verifier); 6112 } 6113 #endif 6114 } 6115 6116 double elapsed = os::elapsedTime() - start; 6117 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0); 6118 } 6119 6120 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) { 6121 size_t pre_used = 0; 6122 FreeRegionList local_free_list("Local List for CSet Freeing"); 6123 6124 double young_time_ms = 0.0; 6125 double non_young_time_ms = 0.0; 6126 6127 // Since the collection set is a superset of the the young list, 6128 // all we need to do to clear the young list is clear its 6129 // head and length, and unlink any young regions in the code below 6130 _young_list->clear(); 6131 6132 G1CollectorPolicy* policy = g1_policy(); 6133 6134 double start_sec = os::elapsedTime(); 6135 bool non_young = true; 6136 6137 HeapRegion* cur = cs_head; 6138 int age_bound = -1; 6139 size_t rs_lengths = 0; 6140 6141 while (cur != NULL) { 6142 assert(!is_on_master_free_list(cur), "sanity"); 6143 if (non_young) { 6144 if (cur->is_young()) { 6145 double end_sec = os::elapsedTime(); 6146 double elapsed_ms = (end_sec - start_sec) * 1000.0; 6147 non_young_time_ms += elapsed_ms; 6148 6149 start_sec = os::elapsedTime(); 6150 non_young = false; 6151 } 6152 } else { 6153 if (!cur->is_young()) { 6154 double end_sec = os::elapsedTime(); 6155 double elapsed_ms = (end_sec - start_sec) * 1000.0; 6156 young_time_ms += elapsed_ms; 6157 6158 start_sec = os::elapsedTime(); 6159 non_young = true; 6160 } 6161 } 6162 6163 rs_lengths += cur->rem_set()->occupied_locked(); 6164 6165 HeapRegion* next = cur->next_in_collection_set(); 6166 assert(cur->in_collection_set(), "bad CS"); 6167 cur->set_next_in_collection_set(NULL); 6168 cur->set_in_collection_set(false); 6169 6170 if (cur->is_young()) { 6171 int index = cur->young_index_in_cset(); 6172 assert(index != -1, "invariant"); 6173 assert((uint) index < policy->young_cset_region_length(), "invariant"); 6174 size_t words_survived = _surviving_young_words[index]; 6175 cur->record_surv_words_in_group(words_survived); 6176 6177 // At this point the we have 'popped' cur from the collection set 6178 // (linked via next_in_collection_set()) but it is still in the 6179 // young list (linked via next_young_region()). Clear the 6180 // _next_young_region field. 6181 cur->set_next_young_region(NULL); 6182 } else { 6183 int index = cur->young_index_in_cset(); 6184 assert(index == -1, "invariant"); 6185 } 6186 6187 assert( (cur->is_young() && cur->young_index_in_cset() > -1) || 6188 (!cur->is_young() && cur->young_index_in_cset() == -1), 6189 "invariant" ); 6190 6191 if (!cur->evacuation_failed()) { 6192 MemRegion used_mr = cur->used_region(); 6193 6194 // And the region is empty. 6195 assert(!used_mr.is_empty(), "Should not have empty regions in a CS."); 6196 pre_used += cur->used(); 6197 free_region(cur, &local_free_list, false /* par */, true /* locked */); 6198 } else { 6199 cur->uninstall_surv_rate_group(); 6200 if (cur->is_young()) { 6201 cur->set_young_index_in_cset(-1); 6202 } 6203 cur->set_not_young(); 6204 cur->set_evacuation_failed(false); 6205 // The region is now considered to be old. 6206 _old_set.add(cur); 6207 evacuation_info.increment_collectionset_used_after(cur->used()); 6208 } 6209 cur = next; 6210 } 6211 6212 evacuation_info.set_regions_freed(local_free_list.length()); 6213 policy->record_max_rs_lengths(rs_lengths); 6214 policy->cset_regions_freed(); 6215 6216 double end_sec = os::elapsedTime(); 6217 double elapsed_ms = (end_sec - start_sec) * 1000.0; 6218 6219 if (non_young) { 6220 non_young_time_ms += elapsed_ms; 6221 } else { 6222 young_time_ms += elapsed_ms; 6223 } 6224 6225 prepend_to_freelist(&local_free_list); 6226 decrement_summary_bytes(pre_used); 6227 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms); 6228 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms); 6229 } 6230 6231 // This routine is similar to the above but does not record 6232 // any policy statistics or update free lists; we are abandoning 6233 // the current incremental collection set in preparation of a 6234 // full collection. After the full GC we will start to build up 6235 // the incremental collection set again. 6236 // This is only called when we're doing a full collection 6237 // and is immediately followed by the tearing down of the young list. 6238 6239 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) { 6240 HeapRegion* cur = cs_head; 6241 6242 while (cur != NULL) { 6243 HeapRegion* next = cur->next_in_collection_set(); 6244 assert(cur->in_collection_set(), "bad CS"); 6245 cur->set_next_in_collection_set(NULL); 6246 cur->set_in_collection_set(false); 6247 cur->set_young_index_in_cset(-1); 6248 cur = next; 6249 } 6250 } 6251 6252 void G1CollectedHeap::set_free_regions_coming() { 6253 if (G1ConcRegionFreeingVerbose) { 6254 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " 6255 "setting free regions coming"); 6256 } 6257 6258 assert(!free_regions_coming(), "pre-condition"); 6259 _free_regions_coming = true; 6260 } 6261 6262 void G1CollectedHeap::reset_free_regions_coming() { 6263 assert(free_regions_coming(), "pre-condition"); 6264 6265 { 6266 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6267 _free_regions_coming = false; 6268 SecondaryFreeList_lock->notify_all(); 6269 } 6270 6271 if (G1ConcRegionFreeingVerbose) { 6272 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " 6273 "reset free regions coming"); 6274 } 6275 } 6276 6277 void G1CollectedHeap::wait_while_free_regions_coming() { 6278 // Most of the time we won't have to wait, so let's do a quick test 6279 // first before we take the lock. 6280 if (!free_regions_coming()) { 6281 return; 6282 } 6283 6284 if (G1ConcRegionFreeingVerbose) { 6285 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " 6286 "waiting for free regions"); 6287 } 6288 6289 { 6290 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6291 while (free_regions_coming()) { 6292 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 6293 } 6294 } 6295 6296 if (G1ConcRegionFreeingVerbose) { 6297 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " 6298 "done waiting for free regions"); 6299 } 6300 } 6301 6302 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 6303 assert(heap_lock_held_for_gc(), 6304 "the heap lock should already be held by or for this thread"); 6305 _young_list->push_region(hr); 6306 } 6307 6308 class NoYoungRegionsClosure: public HeapRegionClosure { 6309 private: 6310 bool _success; 6311 public: 6312 NoYoungRegionsClosure() : _success(true) { } 6313 bool doHeapRegion(HeapRegion* r) { 6314 if (r->is_young()) { 6315 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young", 6316 r->bottom(), r->end()); 6317 _success = false; 6318 } 6319 return false; 6320 } 6321 bool success() { return _success; } 6322 }; 6323 6324 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) { 6325 bool ret = _young_list->check_list_empty(check_sample); 6326 6327 if (check_heap) { 6328 NoYoungRegionsClosure closure; 6329 heap_region_iterate(&closure); 6330 ret = ret && closure.success(); 6331 } 6332 6333 return ret; 6334 } 6335 6336 class TearDownRegionSetsClosure : public HeapRegionClosure { 6337 private: 6338 HeapRegionSet *_old_set; 6339 6340 public: 6341 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { } 6342 6343 bool doHeapRegion(HeapRegion* r) { 6344 if (r->is_empty()) { 6345 // We ignore empty regions, we'll empty the free list afterwards 6346 } else if (r->is_young()) { 6347 // We ignore young regions, we'll empty the young list afterwards 6348 } else if (r->isHumongous()) { 6349 // We ignore humongous regions, we're not tearing down the 6350 // humongous region set 6351 } else { 6352 // The rest should be old 6353 _old_set->remove(r); 6354 } 6355 return false; 6356 } 6357 6358 ~TearDownRegionSetsClosure() { 6359 assert(_old_set->is_empty(), "post-condition"); 6360 } 6361 }; 6362 6363 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) { 6364 assert_at_safepoint(true /* should_be_vm_thread */); 6365 6366 if (!free_list_only) { 6367 TearDownRegionSetsClosure cl(&_old_set); 6368 heap_region_iterate(&cl); 6369 6370 // Note that emptying the _young_list is postponed and instead done as 6371 // the first step when rebuilding the regions sets again. The reason for 6372 // this is that during a full GC string deduplication needs to know if 6373 // a collected region was young or old when the full GC was initiated. 6374 } 6375 _free_list.remove_all(); 6376 } 6377 6378 class RebuildRegionSetsClosure : public HeapRegionClosure { 6379 private: 6380 bool _free_list_only; 6381 HeapRegionSet* _old_set; 6382 FreeRegionList* _free_list; 6383 size_t _total_used; 6384 6385 public: 6386 RebuildRegionSetsClosure(bool free_list_only, 6387 HeapRegionSet* old_set, FreeRegionList* free_list) : 6388 _free_list_only(free_list_only), 6389 _old_set(old_set), _free_list(free_list), _total_used(0) { 6390 assert(_free_list->is_empty(), "pre-condition"); 6391 if (!free_list_only) { 6392 assert(_old_set->is_empty(), "pre-condition"); 6393 } 6394 } 6395 6396 bool doHeapRegion(HeapRegion* r) { 6397 if (r->continuesHumongous()) { 6398 return false; 6399 } 6400 6401 if (r->is_empty()) { 6402 // Add free regions to the free list 6403 _free_list->add_as_tail(r); 6404 } else if (!_free_list_only) { 6405 assert(!r->is_young(), "we should not come across young regions"); 6406 6407 if (r->isHumongous()) { 6408 // We ignore humongous regions, we left the humongous set unchanged 6409 } else { 6410 // The rest should be old, add them to the old set 6411 _old_set->add(r); 6412 } 6413 _total_used += r->used(); 6414 } 6415 6416 return false; 6417 } 6418 6419 size_t total_used() { 6420 return _total_used; 6421 } 6422 }; 6423 6424 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { 6425 assert_at_safepoint(true /* should_be_vm_thread */); 6426 6427 if (!free_list_only) { 6428 _young_list->empty_list(); 6429 } 6430 6431 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_free_list); 6432 heap_region_iterate(&cl); 6433 6434 if (!free_list_only) { 6435 _summary_bytes_used = cl.total_used(); 6436 } 6437 assert(_summary_bytes_used == recalculate_used(), 6438 err_msg("inconsistent _summary_bytes_used, " 6439 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT, 6440 _summary_bytes_used, recalculate_used())); 6441 } 6442 6443 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) { 6444 _refine_cte_cl->set_concurrent(concurrent); 6445 } 6446 6447 bool G1CollectedHeap::is_in_closed_subset(const void* p) const { 6448 HeapRegion* hr = heap_region_containing(p); 6449 return hr->is_in(p); 6450 } 6451 6452 // Methods for the mutator alloc region 6453 6454 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 6455 bool force) { 6456 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6457 assert(!force || g1_policy()->can_expand_young_list(), 6458 "if force is true we should be able to expand the young list"); 6459 bool young_list_full = g1_policy()->is_young_list_full(); 6460 if (force || !young_list_full) { 6461 HeapRegion* new_alloc_region = new_region(word_size, 6462 false /* is_old */, 6463 false /* do_expand */); 6464 if (new_alloc_region != NULL) { 6465 set_region_short_lived_locked(new_alloc_region); 6466 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full); 6467 return new_alloc_region; 6468 } 6469 } 6470 return NULL; 6471 } 6472 6473 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 6474 size_t allocated_bytes) { 6475 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6476 assert(alloc_region->is_young(), "all mutator alloc regions should be young"); 6477 6478 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region); 6479 _summary_bytes_used += allocated_bytes; 6480 _hr_printer.retire(alloc_region); 6481 // We update the eden sizes here, when the region is retired, 6482 // instead of when it's allocated, since this is the point that its 6483 // used space has been recored in _summary_bytes_used. 6484 g1mm()->update_eden_size(); 6485 } 6486 6487 HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size, 6488 bool force) { 6489 return _g1h->new_mutator_alloc_region(word_size, force); 6490 } 6491 6492 void G1CollectedHeap::set_par_threads() { 6493 // Don't change the number of workers. Use the value previously set 6494 // in the workgroup. 6495 assert(G1CollectedHeap::use_parallel_gc_threads(), "shouldn't be here otherwise"); 6496 uint n_workers = workers()->active_workers(); 6497 assert(UseDynamicNumberOfGCThreads || 6498 n_workers == workers()->total_workers(), 6499 "Otherwise should be using the total number of workers"); 6500 if (n_workers == 0) { 6501 assert(false, "Should have been set in prior evacuation pause."); 6502 n_workers = ParallelGCThreads; 6503 workers()->set_active_workers(n_workers); 6504 } 6505 set_par_threads(n_workers); 6506 } 6507 6508 void MutatorAllocRegion::retire_region(HeapRegion* alloc_region, 6509 size_t allocated_bytes) { 6510 _g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes); 6511 } 6512 6513 // Methods for the GC alloc regions 6514 6515 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, 6516 uint count, 6517 GCAllocPurpose ap) { 6518 assert(FreeList_lock->owned_by_self(), "pre-condition"); 6519 6520 if (count < g1_policy()->max_regions(ap)) { 6521 bool survivor = (ap == GCAllocForSurvived); 6522 HeapRegion* new_alloc_region = new_region(word_size, 6523 !survivor, 6524 true /* do_expand */); 6525 if (new_alloc_region != NULL) { 6526 // We really only need to do this for old regions given that we 6527 // should never scan survivors. But it doesn't hurt to do it 6528 // for survivors too. 6529 new_alloc_region->set_saved_mark(); 6530 if (survivor) { 6531 new_alloc_region->set_survivor(); 6532 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor); 6533 } else { 6534 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old); 6535 } 6536 bool during_im = g1_policy()->during_initial_mark_pause(); 6537 new_alloc_region->note_start_of_copying(during_im); 6538 return new_alloc_region; 6539 } else { 6540 g1_policy()->note_alloc_region_limit_reached(ap); 6541 } 6542 } 6543 return NULL; 6544 } 6545 6546 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 6547 size_t allocated_bytes, 6548 GCAllocPurpose ap) { 6549 bool during_im = g1_policy()->during_initial_mark_pause(); 6550 alloc_region->note_end_of_copying(during_im); 6551 g1_policy()->record_bytes_copied_during_gc(allocated_bytes); 6552 if (ap == GCAllocForSurvived) { 6553 young_list()->add_survivor_region(alloc_region); 6554 } else { 6555 _old_set.add(alloc_region); 6556 } 6557 _hr_printer.retire(alloc_region); 6558 } 6559 6560 HeapRegion* SurvivorGCAllocRegion::allocate_new_region(size_t word_size, 6561 bool force) { 6562 assert(!force, "not supported for GC alloc regions"); 6563 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForSurvived); 6564 } 6565 6566 void SurvivorGCAllocRegion::retire_region(HeapRegion* alloc_region, 6567 size_t allocated_bytes) { 6568 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes, 6569 GCAllocForSurvived); 6570 } 6571 6572 HeapRegion* OldGCAllocRegion::allocate_new_region(size_t word_size, 6573 bool force) { 6574 assert(!force, "not supported for GC alloc regions"); 6575 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForTenured); 6576 } 6577 6578 void OldGCAllocRegion::retire_region(HeapRegion* alloc_region, 6579 size_t allocated_bytes) { 6580 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes, 6581 GCAllocForTenured); 6582 } 6583 // Heap region set verification 6584 6585 class VerifyRegionListsClosure : public HeapRegionClosure { 6586 private: 6587 HeapRegionSet* _old_set; 6588 HeapRegionSet* _humongous_set; 6589 FreeRegionList* _free_list; 6590 6591 public: 6592 HeapRegionSetCount _old_count; 6593 HeapRegionSetCount _humongous_count; 6594 HeapRegionSetCount _free_count; 6595 6596 VerifyRegionListsClosure(HeapRegionSet* old_set, 6597 HeapRegionSet* humongous_set, 6598 FreeRegionList* free_list) : 6599 _old_set(old_set), _humongous_set(humongous_set), _free_list(free_list), 6600 _old_count(), _humongous_count(), _free_count(){ } 6601 6602 bool doHeapRegion(HeapRegion* hr) { 6603 if (hr->continuesHumongous()) { 6604 return false; 6605 } 6606 6607 if (hr->is_young()) { 6608 // TODO 6609 } else if (hr->startsHumongous()) { 6610 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrs_index())); 6611 _humongous_count.increment(1u, hr->capacity()); 6612 } else if (hr->is_empty()) { 6613 assert(hr->containing_set() == _free_list, err_msg("Heap region %u is empty but not on the free list.", hr->hrs_index())); 6614 _free_count.increment(1u, hr->capacity()); 6615 } else { 6616 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrs_index())); 6617 _old_count.increment(1u, hr->capacity()); 6618 } 6619 return false; 6620 } 6621 6622 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, FreeRegionList* free_list) { 6623 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length())); 6624 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6625 old_set->total_capacity_bytes(), _old_count.capacity())); 6626 6627 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length())); 6628 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6629 humongous_set->total_capacity_bytes(), _humongous_count.capacity())); 6630 6631 guarantee(free_list->length() == _free_count.length(), err_msg("Free list count mismatch. Expected %u, actual %u.", free_list->length(), _free_count.length())); 6632 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6633 free_list->total_capacity_bytes(), _free_count.capacity())); 6634 } 6635 }; 6636 6637 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index, 6638 HeapWord* bottom) { 6639 HeapWord* end = bottom + HeapRegion::GrainWords; 6640 MemRegion mr(bottom, end); 6641 assert(_g1_reserved.contains(mr), "invariant"); 6642 // This might return NULL if the allocation fails 6643 return new HeapRegion(hrs_index, _bot_shared, mr); 6644 } 6645 6646 void G1CollectedHeap::verify_region_sets() { 6647 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6648 6649 // First, check the explicit lists. 6650 _free_list.verify_list(); 6651 { 6652 // Given that a concurrent operation might be adding regions to 6653 // the secondary free list we have to take the lock before 6654 // verifying it. 6655 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6656 _secondary_free_list.verify_list(); 6657 } 6658 6659 // If a concurrent region freeing operation is in progress it will 6660 // be difficult to correctly attributed any free regions we come 6661 // across to the correct free list given that they might belong to 6662 // one of several (free_list, secondary_free_list, any local lists, 6663 // etc.). So, if that's the case we will skip the rest of the 6664 // verification operation. Alternatively, waiting for the concurrent 6665 // operation to complete will have a non-trivial effect on the GC's 6666 // operation (no concurrent operation will last longer than the 6667 // interval between two calls to verification) and it might hide 6668 // any issues that we would like to catch during testing. 6669 if (free_regions_coming()) { 6670 return; 6671 } 6672 6673 // Make sure we append the secondary_free_list on the free_list so 6674 // that all free regions we will come across can be safely 6675 // attributed to the free_list. 6676 append_secondary_free_list_if_not_empty_with_lock(); 6677 6678 // Finally, make sure that the region accounting in the lists is 6679 // consistent with what we see in the heap. 6680 6681 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_free_list); 6682 heap_region_iterate(&cl); 6683 cl.verify_counts(&_old_set, &_humongous_set, &_free_list); 6684 } 6685 6686 // Optimized nmethod scanning 6687 6688 class RegisterNMethodOopClosure: public OopClosure { 6689 G1CollectedHeap* _g1h; 6690 nmethod* _nm; 6691 6692 template <class T> void do_oop_work(T* p) { 6693 T heap_oop = oopDesc::load_heap_oop(p); 6694 if (!oopDesc::is_null(heap_oop)) { 6695 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 6696 HeapRegion* hr = _g1h->heap_region_containing(obj); 6697 assert(!hr->continuesHumongous(), 6698 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT 6699 " starting at "HR_FORMAT, 6700 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()))); 6701 6702 // HeapRegion::add_strong_code_root() avoids adding duplicate 6703 // entries but having duplicates is OK since we "mark" nmethods 6704 // as visited when we scan the strong code root lists during the GC. 6705 hr->add_strong_code_root(_nm); 6706 assert(hr->rem_set()->strong_code_roots_list_contains(_nm), 6707 err_msg("failed to add code root "PTR_FORMAT" to remembered set of region "HR_FORMAT, 6708 _nm, HR_FORMAT_PARAMS(hr))); 6709 } 6710 } 6711 6712 public: 6713 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 6714 _g1h(g1h), _nm(nm) {} 6715 6716 void do_oop(oop* p) { do_oop_work(p); } 6717 void do_oop(narrowOop* p) { do_oop_work(p); } 6718 }; 6719 6720 class UnregisterNMethodOopClosure: public OopClosure { 6721 G1CollectedHeap* _g1h; 6722 nmethod* _nm; 6723 6724 template <class T> void do_oop_work(T* p) { 6725 T heap_oop = oopDesc::load_heap_oop(p); 6726 if (!oopDesc::is_null(heap_oop)) { 6727 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 6728 HeapRegion* hr = _g1h->heap_region_containing(obj); 6729 assert(!hr->continuesHumongous(), 6730 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT 6731 " starting at "HR_FORMAT, 6732 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()))); 6733 6734 hr->remove_strong_code_root(_nm); 6735 assert(!hr->rem_set()->strong_code_roots_list_contains(_nm), 6736 err_msg("failed to remove code root "PTR_FORMAT" of region "HR_FORMAT, 6737 _nm, HR_FORMAT_PARAMS(hr))); 6738 } 6739 } 6740 6741 public: 6742 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 6743 _g1h(g1h), _nm(nm) {} 6744 6745 void do_oop(oop* p) { do_oop_work(p); } 6746 void do_oop(narrowOop* p) { do_oop_work(p); } 6747 }; 6748 6749 void G1CollectedHeap::register_nmethod(nmethod* nm) { 6750 CollectedHeap::register_nmethod(nm); 6751 6752 guarantee(nm != NULL, "sanity"); 6753 RegisterNMethodOopClosure reg_cl(this, nm); 6754 nm->oops_do(®_cl); 6755 } 6756 6757 void G1CollectedHeap::unregister_nmethod(nmethod* nm) { 6758 CollectedHeap::unregister_nmethod(nm); 6759 6760 guarantee(nm != NULL, "sanity"); 6761 UnregisterNMethodOopClosure reg_cl(this, nm); 6762 nm->oops_do(®_cl, true); 6763 } 6764 6765 class MigrateCodeRootsHeapRegionClosure: public HeapRegionClosure { 6766 public: 6767 bool doHeapRegion(HeapRegion *hr) { 6768 assert(!hr->isHumongous(), 6769 err_msg("humongous region "HR_FORMAT" should not have been added to collection set", 6770 HR_FORMAT_PARAMS(hr))); 6771 hr->migrate_strong_code_roots(); 6772 return false; 6773 } 6774 }; 6775 6776 void G1CollectedHeap::migrate_strong_code_roots() { 6777 MigrateCodeRootsHeapRegionClosure cl; 6778 double migrate_start = os::elapsedTime(); 6779 collection_set_iterate(&cl); 6780 double migration_time_ms = (os::elapsedTime() - migrate_start) * 1000.0; 6781 g1_policy()->phase_times()->record_strong_code_root_migration_time(migration_time_ms); 6782 } 6783 6784 void G1CollectedHeap::purge_code_root_memory() { 6785 double purge_start = os::elapsedTime(); 6786 G1CodeRootSet::purge_chunks(G1CodeRootsChunkCacheKeepPercent); 6787 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0; 6788 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms); 6789 } 6790 6791 // Mark all the code roots that point into regions *not* in the 6792 // collection set. 6793 // 6794 // Note we do not want to use a "marking" CodeBlobToOopClosure while 6795 // walking the the code roots lists of regions not in the collection 6796 // set. Suppose we have an nmethod (M) that points to objects in two 6797 // separate regions - one in the collection set (R1) and one not (R2). 6798 // Using a "marking" CodeBlobToOopClosure here would result in "marking" 6799 // nmethod M when walking the code roots for R1. When we come to scan 6800 // the code roots for R2, we would see that M is already marked and it 6801 // would be skipped and the objects in R2 that are referenced from M 6802 // would not be evacuated. 6803 6804 class MarkStrongCodeRootCodeBlobClosure: public CodeBlobClosure { 6805 6806 class MarkStrongCodeRootOopClosure: public OopClosure { 6807 ConcurrentMark* _cm; 6808 HeapRegion* _hr; 6809 uint _worker_id; 6810 6811 template <class T> void do_oop_work(T* p) { 6812 T heap_oop = oopDesc::load_heap_oop(p); 6813 if (!oopDesc::is_null(heap_oop)) { 6814 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 6815 // Only mark objects in the region (which is assumed 6816 // to be not in the collection set). 6817 if (_hr->is_in(obj)) { 6818 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id); 6819 } 6820 } 6821 } 6822 6823 public: 6824 MarkStrongCodeRootOopClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id) : 6825 _cm(cm), _hr(hr), _worker_id(worker_id) { 6826 assert(!_hr->in_collection_set(), "sanity"); 6827 } 6828 6829 void do_oop(narrowOop* p) { do_oop_work(p); } 6830 void do_oop(oop* p) { do_oop_work(p); } 6831 }; 6832 6833 MarkStrongCodeRootOopClosure _oop_cl; 6834 6835 public: 6836 MarkStrongCodeRootCodeBlobClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id): 6837 _oop_cl(cm, hr, worker_id) {} 6838 6839 void do_code_blob(CodeBlob* cb) { 6840 nmethod* nm = (cb == NULL) ? NULL : cb->as_nmethod_or_null(); 6841 if (nm != NULL) { 6842 nm->oops_do(&_oop_cl); 6843 } 6844 } 6845 }; 6846 6847 class MarkStrongCodeRootsHRClosure: public HeapRegionClosure { 6848 G1CollectedHeap* _g1h; 6849 uint _worker_id; 6850 6851 public: 6852 MarkStrongCodeRootsHRClosure(G1CollectedHeap* g1h, uint worker_id) : 6853 _g1h(g1h), _worker_id(worker_id) {} 6854 6855 bool doHeapRegion(HeapRegion *hr) { 6856 HeapRegionRemSet* hrrs = hr->rem_set(); 6857 if (hr->continuesHumongous()) { 6858 // Code roots should never be attached to a continuation of a humongous region 6859 assert(hrrs->strong_code_roots_list_length() == 0, 6860 err_msg("code roots should never be attached to continuations of humongous region "HR_FORMAT 6861 " starting at "HR_FORMAT", but has "SIZE_FORMAT, 6862 HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()), 6863 hrrs->strong_code_roots_list_length())); 6864 return false; 6865 } 6866 6867 if (hr->in_collection_set()) { 6868 // Don't mark code roots into regions in the collection set here. 6869 // They will be marked when we scan them. 6870 return false; 6871 } 6872 6873 MarkStrongCodeRootCodeBlobClosure cb_cl(_g1h->concurrent_mark(), hr, _worker_id); 6874 hr->strong_code_roots_do(&cb_cl); 6875 return false; 6876 } 6877 }; 6878 6879 void G1CollectedHeap::mark_strong_code_roots(uint worker_id) { 6880 MarkStrongCodeRootsHRClosure cl(this, worker_id); 6881 if (G1CollectedHeap::use_parallel_gc_threads()) { 6882 heap_region_par_iterate_chunked(&cl, 6883 worker_id, 6884 workers()->active_workers(), 6885 HeapRegion::ParMarkRootClaimValue); 6886 } else { 6887 heap_region_iterate(&cl); 6888 } 6889 } 6890 6891 class RebuildStrongCodeRootClosure: public CodeBlobClosure { 6892 G1CollectedHeap* _g1h; 6893 6894 public: 6895 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) : 6896 _g1h(g1h) {} 6897 6898 void do_code_blob(CodeBlob* cb) { 6899 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL; 6900 if (nm == NULL) { 6901 return; 6902 } 6903 6904 if (ScavengeRootsInCode && nm->detect_scavenge_root_oops()) { 6905 _g1h->register_nmethod(nm); 6906 } 6907 } 6908 }; 6909 6910 void G1CollectedHeap::rebuild_strong_code_roots() { 6911 RebuildStrongCodeRootClosure blob_cl(this); 6912 CodeCache::blobs_do(&blob_cl); 6913 }