1 /* 2 * Copyright (c) 2001, 2014, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #if !defined(__clang_major__) && defined(__GNUC__) 26 #define ATTRIBUTE_PRINTF(x,y) // FIXME, formats are a mess. 27 #endif 28 29 #include "precompiled.hpp" 30 #include "code/codeCache.hpp" 31 #include "code/icBuffer.hpp" 32 #include "gc_implementation/g1/bufferingOopClosure.hpp" 33 #include "gc_implementation/g1/concurrentG1Refine.hpp" 34 #include "gc_implementation/g1/concurrentG1RefineThread.hpp" 35 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp" 36 #include "gc_implementation/g1/g1AllocRegion.inline.hpp" 37 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp" 38 #include "gc_implementation/g1/g1CollectorPolicy.hpp" 39 #include "gc_implementation/g1/g1ErgoVerbose.hpp" 40 #include "gc_implementation/g1/g1EvacFailure.hpp" 41 #include "gc_implementation/g1/g1GCPhaseTimes.hpp" 42 #include "gc_implementation/g1/g1Log.hpp" 43 #include "gc_implementation/g1/g1MarkSweep.hpp" 44 #include "gc_implementation/g1/g1OopClosures.inline.hpp" 45 #include "gc_implementation/g1/g1RemSet.inline.hpp" 46 #include "gc_implementation/g1/g1StringDedup.hpp" 47 #include "gc_implementation/g1/g1YCTypes.hpp" 48 #include "gc_implementation/g1/heapRegion.inline.hpp" 49 #include "gc_implementation/g1/heapRegionRemSet.hpp" 50 #include "gc_implementation/g1/heapRegionSeq.inline.hpp" 51 #include "gc_implementation/g1/vm_operations_g1.hpp" 52 #include "gc_implementation/shared/gcHeapSummary.hpp" 53 #include "gc_implementation/shared/gcTimer.hpp" 54 #include "gc_implementation/shared/gcTrace.hpp" 55 #include "gc_implementation/shared/gcTraceTime.hpp" 56 #include "gc_implementation/shared/isGCActiveMark.hpp" 57 #include "memory/gcLocker.inline.hpp" 58 #include "memory/generationSpec.hpp" 59 #include "memory/iterator.hpp" 60 #include "memory/referenceProcessor.hpp" 61 #include "oops/oop.inline.hpp" 62 #include "oops/oop.pcgc.inline.hpp" 63 #include "runtime/prefetch.inline.hpp" 64 #include "runtime/orderAccess.inline.hpp" 65 #include "runtime/vmThread.hpp" 66 #include "utilities/ticks.hpp" 67 68 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0; 69 70 // turn it on so that the contents of the young list (scan-only / 71 // to-be-collected) are printed at "strategic" points before / during 72 // / after the collection --- this is useful for debugging 73 #define YOUNG_LIST_VERBOSE 0 74 // CURRENT STATUS 75 // This file is under construction. Search for "FIXME". 76 77 // INVARIANTS/NOTES 78 // 79 // All allocation activity covered by the G1CollectedHeap interface is 80 // serialized by acquiring the HeapLock. This happens in mem_allocate 81 // and allocate_new_tlab, which are the "entry" points to the 82 // allocation code from the rest of the JVM. (Note that this does not 83 // apply to TLAB allocation, which is not part of this interface: it 84 // is done by clients of this interface.) 85 86 // Notes on implementation of parallelism in different tasks. 87 // 88 // G1ParVerifyTask uses heap_region_par_iterate_chunked() for parallelism. 89 // The number of GC workers is passed to heap_region_par_iterate_chunked(). 90 // It does use run_task() which sets _n_workers in the task. 91 // G1ParTask executes g1_process_strong_roots() -> 92 // SharedHeap::process_strong_roots() which calls eventually to 93 // CardTableModRefBS::par_non_clean_card_iterate_work() which uses 94 // SequentialSubTasksDone. SharedHeap::process_strong_roots() also 95 // directly uses SubTasksDone (_process_strong_tasks field in SharedHeap). 96 // 97 98 // Local to this file. 99 100 class RefineCardTableEntryClosure: public CardTableEntryClosure { 101 G1RemSet* _g1rs; 102 ConcurrentG1Refine* _cg1r; 103 bool _concurrent; 104 public: 105 RefineCardTableEntryClosure(G1RemSet* g1rs, 106 ConcurrentG1Refine* cg1r) : 107 _g1rs(g1rs), _cg1r(cg1r), _concurrent(true) 108 {} 109 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 110 bool oops_into_cset = _g1rs->refine_card(card_ptr, worker_i, false); 111 // This path is executed by the concurrent refine or mutator threads, 112 // concurrently, and so we do not care if card_ptr contains references 113 // that point into the collection set. 114 assert(!oops_into_cset, "should be"); 115 116 if (_concurrent && SuspendibleThreadSet::should_yield()) { 117 // Caller will actually yield. 118 return false; 119 } 120 // Otherwise, we finished successfully; return true. 121 return true; 122 } 123 void set_concurrent(bool b) { _concurrent = b; } 124 }; 125 126 127 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure { 128 int _calls; 129 G1CollectedHeap* _g1h; 130 CardTableModRefBS* _ctbs; 131 int _histo[256]; 132 public: 133 ClearLoggedCardTableEntryClosure() : 134 _calls(0), _g1h(G1CollectedHeap::heap()), _ctbs(_g1h->g1_barrier_set()) 135 { 136 for (int i = 0; i < 256; i++) _histo[i] = 0; 137 } 138 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 139 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) { 140 _calls++; 141 unsigned char* ujb = (unsigned char*)card_ptr; 142 int ind = (int)(*ujb); 143 _histo[ind]++; 144 *card_ptr = -1; 145 } 146 return true; 147 } 148 int calls() { return _calls; } 149 void print_histo() { 150 gclog_or_tty->print_cr("Card table value histogram:"); 151 for (int i = 0; i < 256; i++) { 152 if (_histo[i] != 0) { 153 gclog_or_tty->print_cr(" %d: %d", i, _histo[i]); 154 } 155 } 156 } 157 }; 158 159 class RedirtyLoggedCardTableEntryClosure: public CardTableEntryClosure { 160 int _calls; 161 G1CollectedHeap* _g1h; 162 CardTableModRefBS* _ctbs; 163 public: 164 RedirtyLoggedCardTableEntryClosure() : 165 _calls(0), _g1h(G1CollectedHeap::heap()), _ctbs(_g1h->g1_barrier_set()) {} 166 167 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 168 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) { 169 _calls++; 170 *card_ptr = 0; 171 } 172 return true; 173 } 174 int calls() { return _calls; } 175 }; 176 177 YoungList::YoungList(G1CollectedHeap* g1h) : 178 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0), 179 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) { 180 guarantee(check_list_empty(false), "just making sure..."); 181 } 182 183 void YoungList::push_region(HeapRegion *hr) { 184 assert(!hr->is_young(), "should not already be young"); 185 assert(hr->get_next_young_region() == NULL, "cause it should!"); 186 187 hr->set_next_young_region(_head); 188 _head = hr; 189 190 _g1h->g1_policy()->set_region_eden(hr, (int) _length); 191 ++_length; 192 } 193 194 void YoungList::add_survivor_region(HeapRegion* hr) { 195 assert(hr->is_survivor(), "should be flagged as survivor region"); 196 assert(hr->get_next_young_region() == NULL, "cause it should!"); 197 198 hr->set_next_young_region(_survivor_head); 199 if (_survivor_head == NULL) { 200 _survivor_tail = hr; 201 } 202 _survivor_head = hr; 203 ++_survivor_length; 204 } 205 206 void YoungList::empty_list(HeapRegion* list) { 207 while (list != NULL) { 208 HeapRegion* next = list->get_next_young_region(); 209 list->set_next_young_region(NULL); 210 list->uninstall_surv_rate_group(); 211 list->set_not_young(); 212 list = next; 213 } 214 } 215 216 void YoungList::empty_list() { 217 assert(check_list_well_formed(), "young list should be well formed"); 218 219 empty_list(_head); 220 _head = NULL; 221 _length = 0; 222 223 empty_list(_survivor_head); 224 _survivor_head = NULL; 225 _survivor_tail = NULL; 226 _survivor_length = 0; 227 228 _last_sampled_rs_lengths = 0; 229 230 assert(check_list_empty(false), "just making sure..."); 231 } 232 233 bool YoungList::check_list_well_formed() { 234 bool ret = true; 235 236 uint length = 0; 237 HeapRegion* curr = _head; 238 HeapRegion* last = NULL; 239 while (curr != NULL) { 240 if (!curr->is_young()) { 241 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" " 242 "incorrectly tagged (y: %d, surv: %d)", 243 curr->bottom(), curr->end(), 244 curr->is_young(), curr->is_survivor()); 245 ret = false; 246 } 247 ++length; 248 last = curr; 249 curr = curr->get_next_young_region(); 250 } 251 ret = ret && (length == _length); 252 253 if (!ret) { 254 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!"); 255 gclog_or_tty->print_cr("### list has %u entries, _length is %u", 256 length, _length); 257 } 258 259 return ret; 260 } 261 262 bool YoungList::check_list_empty(bool check_sample) { 263 bool ret = true; 264 265 if (_length != 0) { 266 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u", 267 _length); 268 ret = false; 269 } 270 if (check_sample && _last_sampled_rs_lengths != 0) { 271 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths"); 272 ret = false; 273 } 274 if (_head != NULL) { 275 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head"); 276 ret = false; 277 } 278 if (!ret) { 279 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty"); 280 } 281 282 return ret; 283 } 284 285 void 286 YoungList::rs_length_sampling_init() { 287 _sampled_rs_lengths = 0; 288 _curr = _head; 289 } 290 291 bool 292 YoungList::rs_length_sampling_more() { 293 return _curr != NULL; 294 } 295 296 void 297 YoungList::rs_length_sampling_next() { 298 assert( _curr != NULL, "invariant" ); 299 size_t rs_length = _curr->rem_set()->occupied(); 300 301 _sampled_rs_lengths += rs_length; 302 303 // The current region may not yet have been added to the 304 // incremental collection set (it gets added when it is 305 // retired as the current allocation region). 306 if (_curr->in_collection_set()) { 307 // Update the collection set policy information for this region 308 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length); 309 } 310 311 _curr = _curr->get_next_young_region(); 312 if (_curr == NULL) { 313 _last_sampled_rs_lengths = _sampled_rs_lengths; 314 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths); 315 } 316 } 317 318 void 319 YoungList::reset_auxilary_lists() { 320 guarantee( is_empty(), "young list should be empty" ); 321 assert(check_list_well_formed(), "young list should be well formed"); 322 323 // Add survivor regions to SurvRateGroup. 324 _g1h->g1_policy()->note_start_adding_survivor_regions(); 325 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */); 326 327 int young_index_in_cset = 0; 328 for (HeapRegion* curr = _survivor_head; 329 curr != NULL; 330 curr = curr->get_next_young_region()) { 331 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset); 332 333 // The region is a non-empty survivor so let's add it to 334 // the incremental collection set for the next evacuation 335 // pause. 336 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr); 337 young_index_in_cset += 1; 338 } 339 assert((uint) young_index_in_cset == _survivor_length, "post-condition"); 340 _g1h->g1_policy()->note_stop_adding_survivor_regions(); 341 342 _head = _survivor_head; 343 _length = _survivor_length; 344 if (_survivor_head != NULL) { 345 assert(_survivor_tail != NULL, "cause it shouldn't be"); 346 assert(_survivor_length > 0, "invariant"); 347 _survivor_tail->set_next_young_region(NULL); 348 } 349 350 // Don't clear the survivor list handles until the start of 351 // the next evacuation pause - we need it in order to re-tag 352 // the survivor regions from this evacuation pause as 'young' 353 // at the start of the next. 354 355 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */); 356 357 assert(check_list_well_formed(), "young list should be well formed"); 358 } 359 360 void YoungList::print() { 361 HeapRegion* lists[] = {_head, _survivor_head}; 362 const char* names[] = {"YOUNG", "SURVIVOR"}; 363 364 for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) { 365 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]); 366 HeapRegion *curr = lists[list]; 367 if (curr == NULL) 368 gclog_or_tty->print_cr(" empty"); 369 while (curr != NULL) { 370 gclog_or_tty->print_cr(" "HR_FORMAT", P: "PTR_FORMAT "N: "PTR_FORMAT", age: %4d", 371 HR_FORMAT_PARAMS(curr), 372 curr->prev_top_at_mark_start(), 373 curr->next_top_at_mark_start(), 374 curr->age_in_surv_rate_group_cond()); 375 curr = curr->get_next_young_region(); 376 } 377 } 378 379 gclog_or_tty->cr(); 380 } 381 382 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr) 383 { 384 // Claim the right to put the region on the dirty cards region list 385 // by installing a self pointer. 386 HeapRegion* next = hr->get_next_dirty_cards_region(); 387 if (next == NULL) { 388 HeapRegion* res = (HeapRegion*) 389 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(), 390 NULL); 391 if (res == NULL) { 392 HeapRegion* head; 393 do { 394 // Put the region to the dirty cards region list. 395 head = _dirty_cards_region_list; 396 next = (HeapRegion*) 397 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head); 398 if (next == head) { 399 assert(hr->get_next_dirty_cards_region() == hr, 400 "hr->get_next_dirty_cards_region() != hr"); 401 if (next == NULL) { 402 // The last region in the list points to itself. 403 hr->set_next_dirty_cards_region(hr); 404 } else { 405 hr->set_next_dirty_cards_region(next); 406 } 407 } 408 } while (next != head); 409 } 410 } 411 } 412 413 HeapRegion* G1CollectedHeap::pop_dirty_cards_region() 414 { 415 HeapRegion* head; 416 HeapRegion* hr; 417 do { 418 head = _dirty_cards_region_list; 419 if (head == NULL) { 420 return NULL; 421 } 422 HeapRegion* new_head = head->get_next_dirty_cards_region(); 423 if (head == new_head) { 424 // The last region. 425 new_head = NULL; 426 } 427 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list, 428 head); 429 } while (hr != head); 430 assert(hr != NULL, "invariant"); 431 hr->set_next_dirty_cards_region(NULL); 432 return hr; 433 } 434 435 #ifdef ASSERT 436 // A region is added to the collection set as it is retired 437 // so an address p can point to a region which will be in the 438 // collection set but has not yet been retired. This method 439 // therefore is only accurate during a GC pause after all 440 // regions have been retired. It is used for debugging 441 // to check if an nmethod has references to objects that can 442 // be move during a partial collection. Though it can be 443 // inaccurate, it is sufficient for G1 because the conservative 444 // implementation of is_scavengable() for G1 will indicate that 445 // all nmethods must be scanned during a partial collection. 446 bool G1CollectedHeap::is_in_partial_collection(const void* p) { 447 HeapRegion* hr = heap_region_containing(p); 448 return hr != NULL && hr->in_collection_set(); 449 } 450 #endif 451 452 // Returns true if the reference points to an object that 453 // can move in an incremental collection. 454 bool G1CollectedHeap::is_scavengable(const void* p) { 455 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 456 G1CollectorPolicy* g1p = g1h->g1_policy(); 457 HeapRegion* hr = heap_region_containing(p); 458 if (hr == NULL) { 459 // null 460 assert(p == NULL, err_msg("Not NULL " PTR_FORMAT ,p)); 461 return false; 462 } else { 463 return !hr->isHumongous(); 464 } 465 } 466 467 void G1CollectedHeap::check_ct_logs_at_safepoint() { 468 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 469 CardTableModRefBS* ct_bs = g1_barrier_set(); 470 471 // Count the dirty cards at the start. 472 CountNonCleanMemRegionClosure count1(this); 473 ct_bs->mod_card_iterate(&count1); 474 int orig_count = count1.n(); 475 476 // First clear the logged cards. 477 ClearLoggedCardTableEntryClosure clear; 478 dcqs.set_closure(&clear); 479 dcqs.apply_closure_to_all_completed_buffers(); 480 dcqs.iterate_closure_all_threads(false); 481 clear.print_histo(); 482 483 // Now ensure that there's no dirty cards. 484 CountNonCleanMemRegionClosure count2(this); 485 ct_bs->mod_card_iterate(&count2); 486 if (count2.n() != 0) { 487 gclog_or_tty->print_cr("Card table has %d entries; %d originally", 488 count2.n(), orig_count); 489 } 490 guarantee(count2.n() == 0, "Card table should be clean."); 491 492 RedirtyLoggedCardTableEntryClosure redirty; 493 JavaThread::dirty_card_queue_set().set_closure(&redirty); 494 dcqs.apply_closure_to_all_completed_buffers(); 495 dcqs.iterate_closure_all_threads(false); 496 gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.", 497 clear.calls(), orig_count); 498 guarantee(redirty.calls() == clear.calls(), 499 "Or else mechanism is broken."); 500 501 CountNonCleanMemRegionClosure count3(this); 502 ct_bs->mod_card_iterate(&count3); 503 if (count3.n() != orig_count) { 504 gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.", 505 orig_count, count3.n()); 506 guarantee(count3.n() >= orig_count, "Should have restored them all."); 507 } 508 509 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl); 510 } 511 512 // Private class members. 513 514 G1CollectedHeap* G1CollectedHeap::_g1h; 515 516 // Private methods. 517 518 HeapRegion* 519 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) { 520 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 521 while (!_secondary_free_list.is_empty() || free_regions_coming()) { 522 if (!_secondary_free_list.is_empty()) { 523 if (G1ConcRegionFreeingVerbose) { 524 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 525 "secondary_free_list has %u entries", 526 _secondary_free_list.length()); 527 } 528 // It looks as if there are free regions available on the 529 // secondary_free_list. Let's move them to the free_list and try 530 // again to allocate from it. 531 append_secondary_free_list(); 532 533 assert(!_free_list.is_empty(), "if the secondary_free_list was not " 534 "empty we should have moved at least one entry to the free_list"); 535 HeapRegion* res = _free_list.remove_region(is_old); 536 if (G1ConcRegionFreeingVerbose) { 537 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 538 "allocated "HR_FORMAT" from secondary_free_list", 539 HR_FORMAT_PARAMS(res)); 540 } 541 return res; 542 } 543 544 // Wait here until we get notified either when (a) there are no 545 // more free regions coming or (b) some regions have been moved on 546 // the secondary_free_list. 547 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 548 } 549 550 if (G1ConcRegionFreeingVerbose) { 551 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 552 "could not allocate from secondary_free_list"); 553 } 554 return NULL; 555 } 556 557 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) { 558 assert(!isHumongous(word_size) || word_size <= HeapRegion::GrainWords, 559 "the only time we use this to allocate a humongous region is " 560 "when we are allocating a single humongous region"); 561 562 HeapRegion* res; 563 if (G1StressConcRegionFreeing) { 564 if (!_secondary_free_list.is_empty()) { 565 if (G1ConcRegionFreeingVerbose) { 566 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 567 "forced to look at the secondary_free_list"); 568 } 569 res = new_region_try_secondary_free_list(is_old); 570 if (res != NULL) { 571 return res; 572 } 573 } 574 } 575 576 res = _free_list.remove_region(is_old); 577 578 if (res == NULL) { 579 if (G1ConcRegionFreeingVerbose) { 580 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 581 "res == NULL, trying the secondary_free_list"); 582 } 583 res = new_region_try_secondary_free_list(is_old); 584 } 585 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) { 586 // Currently, only attempts to allocate GC alloc regions set 587 // do_expand to true. So, we should only reach here during a 588 // safepoint. If this assumption changes we might have to 589 // reconsider the use of _expand_heap_after_alloc_failure. 590 assert(SafepointSynchronize::is_at_safepoint(), "invariant"); 591 592 ergo_verbose1(ErgoHeapSizing, 593 "attempt heap expansion", 594 ergo_format_reason("region allocation request failed") 595 ergo_format_byte("allocation request"), 596 word_size * HeapWordSize); 597 if (expand(word_size * HeapWordSize)) { 598 // Given that expand() succeeded in expanding the heap, and we 599 // always expand the heap by an amount aligned to the heap 600 // region size, the free list should in theory not be empty. 601 // In either case remove_region() will check for NULL. 602 res = _free_list.remove_region(is_old); 603 } else { 604 _expand_heap_after_alloc_failure = false; 605 } 606 } 607 return res; 608 } 609 610 uint G1CollectedHeap::humongous_obj_allocate_find_first(uint num_regions, 611 size_t word_size) { 612 assert(isHumongous(word_size), "word_size should be humongous"); 613 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition"); 614 615 uint first = G1_NULL_HRS_INDEX; 616 if (num_regions == 1) { 617 // Only one region to allocate, no need to go through the slower 618 // path. The caller will attempt the expansion if this fails, so 619 // let's not try to expand here too. 620 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */); 621 if (hr != NULL) { 622 first = hr->hrs_index(); 623 } else { 624 first = G1_NULL_HRS_INDEX; 625 } 626 } else { 627 // We can't allocate humongous regions while cleanupComplete() is 628 // running, since some of the regions we find to be empty might not 629 // yet be added to the free list and it is not straightforward to 630 // know which list they are on so that we can remove them. Note 631 // that we only need to do this if we need to allocate more than 632 // one region to satisfy the current humongous allocation 633 // request. If we are only allocating one region we use the common 634 // region allocation code (see above). 635 wait_while_free_regions_coming(); 636 append_secondary_free_list_if_not_empty_with_lock(); 637 638 if (free_regions() >= num_regions) { 639 first = _hrs.find_contiguous(num_regions); 640 if (first != G1_NULL_HRS_INDEX) { 641 for (uint i = first; i < first + num_regions; ++i) { 642 HeapRegion* hr = region_at(i); 643 assert(hr->is_empty(), "sanity"); 644 assert(is_on_master_free_list(hr), "sanity"); 645 hr->set_pending_removal(true); 646 } 647 _free_list.remove_all_pending(num_regions); 648 } 649 } 650 } 651 return first; 652 } 653 654 HeapWord* 655 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first, 656 uint num_regions, 657 size_t word_size) { 658 assert(first != G1_NULL_HRS_INDEX, "pre-condition"); 659 assert(isHumongous(word_size), "word_size should be humongous"); 660 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition"); 661 662 // Index of last region in the series + 1. 663 uint last = first + num_regions; 664 665 // We need to initialize the region(s) we just discovered. This is 666 // a bit tricky given that it can happen concurrently with 667 // refinement threads refining cards on these regions and 668 // potentially wanting to refine the BOT as they are scanning 669 // those cards (this can happen shortly after a cleanup; see CR 670 // 6991377). So we have to set up the region(s) carefully and in 671 // a specific order. 672 673 // The word size sum of all the regions we will allocate. 674 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords; 675 assert(word_size <= word_size_sum, "sanity"); 676 677 // This will be the "starts humongous" region. 678 HeapRegion* first_hr = region_at(first); 679 // The header of the new object will be placed at the bottom of 680 // the first region. 681 HeapWord* new_obj = first_hr->bottom(); 682 // This will be the new end of the first region in the series that 683 // should also match the end of the last region in the series. 684 HeapWord* new_end = new_obj + word_size_sum; 685 // This will be the new top of the first region that will reflect 686 // this allocation. 687 HeapWord* new_top = new_obj + word_size; 688 689 // First, we need to zero the header of the space that we will be 690 // allocating. When we update top further down, some refinement 691 // threads might try to scan the region. By zeroing the header we 692 // ensure that any thread that will try to scan the region will 693 // come across the zero klass word and bail out. 694 // 695 // NOTE: It would not have been correct to have used 696 // CollectedHeap::fill_with_object() and make the space look like 697 // an int array. The thread that is doing the allocation will 698 // later update the object header to a potentially different array 699 // type and, for a very short period of time, the klass and length 700 // fields will be inconsistent. This could cause a refinement 701 // thread to calculate the object size incorrectly. 702 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0); 703 704 // We will set up the first region as "starts humongous". This 705 // will also update the BOT covering all the regions to reflect 706 // that there is a single object that starts at the bottom of the 707 // first region. 708 first_hr->set_startsHumongous(new_top, new_end); 709 710 // Then, if there are any, we will set up the "continues 711 // humongous" regions. 712 HeapRegion* hr = NULL; 713 for (uint i = first + 1; i < last; ++i) { 714 hr = region_at(i); 715 hr->set_continuesHumongous(first_hr); 716 } 717 // If we have "continues humongous" regions (hr != NULL), then the 718 // end of the last one should match new_end. 719 assert(hr == NULL || hr->end() == new_end, "sanity"); 720 721 // Up to this point no concurrent thread would have been able to 722 // do any scanning on any region in this series. All the top 723 // fields still point to bottom, so the intersection between 724 // [bottom,top] and [card_start,card_end] will be empty. Before we 725 // update the top fields, we'll do a storestore to make sure that 726 // no thread sees the update to top before the zeroing of the 727 // object header and the BOT initialization. 728 OrderAccess::storestore(); 729 730 // Now that the BOT and the object header have been initialized, 731 // we can update top of the "starts humongous" region. 732 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(), 733 "new_top should be in this region"); 734 first_hr->set_top(new_top); 735 if (_hr_printer.is_active()) { 736 HeapWord* bottom = first_hr->bottom(); 737 HeapWord* end = first_hr->orig_end(); 738 if ((first + 1) == last) { 739 // the series has a single humongous region 740 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top); 741 } else { 742 // the series has more than one humongous regions 743 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end); 744 } 745 } 746 747 // Now, we will update the top fields of the "continues humongous" 748 // regions. The reason we need to do this is that, otherwise, 749 // these regions would look empty and this will confuse parts of 750 // G1. For example, the code that looks for a consecutive number 751 // of empty regions will consider them empty and try to 752 // re-allocate them. We can extend is_empty() to also include 753 // !continuesHumongous(), but it is easier to just update the top 754 // fields here. The way we set top for all regions (i.e., top == 755 // end for all regions but the last one, top == new_top for the 756 // last one) is actually used when we will free up the humongous 757 // region in free_humongous_region(). 758 hr = NULL; 759 for (uint i = first + 1; i < last; ++i) { 760 hr = region_at(i); 761 if ((i + 1) == last) { 762 // last continues humongous region 763 assert(hr->bottom() < new_top && new_top <= hr->end(), 764 "new_top should fall on this region"); 765 hr->set_top(new_top); 766 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top); 767 } else { 768 // not last one 769 assert(new_top > hr->end(), "new_top should be above this region"); 770 hr->set_top(hr->end()); 771 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end()); 772 } 773 } 774 // If we have continues humongous regions (hr != NULL), then the 775 // end of the last one should match new_end and its top should 776 // match new_top. 777 assert(hr == NULL || 778 (hr->end() == new_end && hr->top() == new_top), "sanity"); 779 780 assert(first_hr->used() == word_size * HeapWordSize, "invariant"); 781 _summary_bytes_used += first_hr->used(); 782 _humongous_set.add(first_hr); 783 784 return new_obj; 785 } 786 787 // If could fit into free regions w/o expansion, try. 788 // Otherwise, if can expand, do so. 789 // Otherwise, if using ex regions might help, try with ex given back. 790 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) { 791 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 792 793 verify_region_sets_optional(); 794 795 size_t word_size_rounded = round_to(word_size, HeapRegion::GrainWords); 796 uint num_regions = (uint) (word_size_rounded / HeapRegion::GrainWords); 797 uint x_num = expansion_regions(); 798 uint fs = _hrs.free_suffix(); 799 uint first = humongous_obj_allocate_find_first(num_regions, word_size); 800 if (first == G1_NULL_HRS_INDEX) { 801 // The only thing we can do now is attempt expansion. 802 if (fs + x_num >= num_regions) { 803 // If the number of regions we're trying to allocate for this 804 // object is at most the number of regions in the free suffix, 805 // then the call to humongous_obj_allocate_find_first() above 806 // should have succeeded and we wouldn't be here. 807 // 808 // We should only be trying to expand when the free suffix is 809 // not sufficient for the object _and_ we have some expansion 810 // room available. 811 assert(num_regions > fs, "earlier allocation should have succeeded"); 812 813 ergo_verbose1(ErgoHeapSizing, 814 "attempt heap expansion", 815 ergo_format_reason("humongous allocation request failed") 816 ergo_format_byte("allocation request"), 817 word_size * HeapWordSize); 818 if (expand((num_regions - fs) * HeapRegion::GrainBytes)) { 819 // Even though the heap was expanded, it might not have 820 // reached the desired size. So, we cannot assume that the 821 // allocation will succeed. 822 first = humongous_obj_allocate_find_first(num_regions, word_size); 823 } 824 } 825 } 826 827 HeapWord* result = NULL; 828 if (first != G1_NULL_HRS_INDEX) { 829 result = 830 humongous_obj_allocate_initialize_regions(first, num_regions, word_size); 831 assert(result != NULL, "it should always return a valid result"); 832 833 // A successful humongous object allocation changes the used space 834 // information of the old generation so we need to recalculate the 835 // sizes and update the jstat counters here. 836 g1mm()->update_sizes(); 837 } 838 839 verify_region_sets_optional(); 840 841 return result; 842 } 843 844 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) { 845 assert_heap_not_locked_and_not_at_safepoint(); 846 assert(!isHumongous(word_size), "we do not allow humongous TLABs"); 847 848 unsigned int dummy_gc_count_before; 849 int dummy_gclocker_retry_count = 0; 850 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count); 851 } 852 853 HeapWord* 854 G1CollectedHeap::mem_allocate(size_t word_size, 855 bool* gc_overhead_limit_was_exceeded) { 856 assert_heap_not_locked_and_not_at_safepoint(); 857 858 // Loop until the allocation is satisfied, or unsatisfied after GC. 859 for (int try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 860 unsigned int gc_count_before; 861 862 HeapWord* result = NULL; 863 if (!isHumongous(word_size)) { 864 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count); 865 } else { 866 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count); 867 } 868 if (result != NULL) { 869 return result; 870 } 871 872 // Create the garbage collection operation... 873 VM_G1CollectForAllocation op(gc_count_before, word_size); 874 // ...and get the VM thread to execute it. 875 VMThread::execute(&op); 876 877 if (op.prologue_succeeded() && op.pause_succeeded()) { 878 // If the operation was successful we'll return the result even 879 // if it is NULL. If the allocation attempt failed immediately 880 // after a Full GC, it's unlikely we'll be able to allocate now. 881 HeapWord* result = op.result(); 882 if (result != NULL && !isHumongous(word_size)) { 883 // Allocations that take place on VM operations do not do any 884 // card dirtying and we have to do it here. We only have to do 885 // this for non-humongous allocations, though. 886 dirty_young_block(result, word_size); 887 } 888 return result; 889 } else { 890 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 891 return NULL; 892 } 893 assert(op.result() == NULL, 894 "the result should be NULL if the VM op did not succeed"); 895 } 896 897 // Give a warning if we seem to be looping forever. 898 if ((QueuedAllocationWarningCount > 0) && 899 (try_count % QueuedAllocationWarningCount == 0)) { 900 warning("G1CollectedHeap::mem_allocate retries %d times", try_count); 901 } 902 } 903 904 ShouldNotReachHere(); 905 return NULL; 906 } 907 908 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size, 909 unsigned int *gc_count_before_ret, 910 int* gclocker_retry_count_ret) { 911 // Make sure you read the note in attempt_allocation_humongous(). 912 913 assert_heap_not_locked_and_not_at_safepoint(); 914 assert(!isHumongous(word_size), "attempt_allocation_slow() should not " 915 "be called for humongous allocation requests"); 916 917 // We should only get here after the first-level allocation attempt 918 // (attempt_allocation()) failed to allocate. 919 920 // We will loop until a) we manage to successfully perform the 921 // allocation or b) we successfully schedule a collection which 922 // fails to perform the allocation. b) is the only case when we'll 923 // return NULL. 924 HeapWord* result = NULL; 925 for (int try_count = 1; /* we'll return */; try_count += 1) { 926 bool should_try_gc; 927 unsigned int gc_count_before; 928 929 { 930 MutexLockerEx x(Heap_lock); 931 932 result = _mutator_alloc_region.attempt_allocation_locked(word_size, 933 false /* bot_updates */); 934 if (result != NULL) { 935 return result; 936 } 937 938 // If we reach here, attempt_allocation_locked() above failed to 939 // allocate a new region. So the mutator alloc region should be NULL. 940 assert(_mutator_alloc_region.get() == NULL, "only way to get here"); 941 942 if (GC_locker::is_active_and_needs_gc()) { 943 if (g1_policy()->can_expand_young_list()) { 944 // No need for an ergo verbose message here, 945 // can_expand_young_list() does this when it returns true. 946 result = _mutator_alloc_region.attempt_allocation_force(word_size, 947 false /* bot_updates */); 948 if (result != NULL) { 949 return result; 950 } 951 } 952 should_try_gc = false; 953 } else { 954 // The GCLocker may not be active but the GCLocker initiated 955 // GC may not yet have been performed (GCLocker::needs_gc() 956 // returns true). In this case we do not try this GC and 957 // wait until the GCLocker initiated GC is performed, and 958 // then retry the allocation. 959 if (GC_locker::needs_gc()) { 960 should_try_gc = false; 961 } else { 962 // Read the GC count while still holding the Heap_lock. 963 gc_count_before = total_collections(); 964 should_try_gc = true; 965 } 966 } 967 } 968 969 if (should_try_gc) { 970 bool succeeded; 971 result = do_collection_pause(word_size, gc_count_before, &succeeded, 972 GCCause::_g1_inc_collection_pause); 973 if (result != NULL) { 974 assert(succeeded, "only way to get back a non-NULL result"); 975 return result; 976 } 977 978 if (succeeded) { 979 // If we get here we successfully scheduled a collection which 980 // failed to allocate. No point in trying to allocate 981 // further. We'll just return NULL. 982 MutexLockerEx x(Heap_lock); 983 *gc_count_before_ret = total_collections(); 984 return NULL; 985 } 986 } else { 987 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { 988 MutexLockerEx x(Heap_lock); 989 *gc_count_before_ret = total_collections(); 990 return NULL; 991 } 992 // The GCLocker is either active or the GCLocker initiated 993 // GC has not yet been performed. Stall until it is and 994 // then retry the allocation. 995 GC_locker::stall_until_clear(); 996 (*gclocker_retry_count_ret) += 1; 997 } 998 999 // We can reach here if we were unsuccessful in scheduling a 1000 // collection (because another thread beat us to it) or if we were 1001 // stalled due to the GC locker. In either can we should retry the 1002 // allocation attempt in case another thread successfully 1003 // performed a collection and reclaimed enough space. We do the 1004 // first attempt (without holding the Heap_lock) here and the 1005 // follow-on attempt will be at the start of the next loop 1006 // iteration (after taking the Heap_lock). 1007 result = _mutator_alloc_region.attempt_allocation(word_size, 1008 false /* bot_updates */); 1009 if (result != NULL) { 1010 return result; 1011 } 1012 1013 // Give a warning if we seem to be looping forever. 1014 if ((QueuedAllocationWarningCount > 0) && 1015 (try_count % QueuedAllocationWarningCount == 0)) { 1016 warning("G1CollectedHeap::attempt_allocation_slow() " 1017 "retries %d times", try_count); 1018 } 1019 } 1020 1021 ShouldNotReachHere(); 1022 return NULL; 1023 } 1024 1025 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size, 1026 unsigned int * gc_count_before_ret, 1027 int* gclocker_retry_count_ret) { 1028 // The structure of this method has a lot of similarities to 1029 // attempt_allocation_slow(). The reason these two were not merged 1030 // into a single one is that such a method would require several "if 1031 // allocation is not humongous do this, otherwise do that" 1032 // conditional paths which would obscure its flow. In fact, an early 1033 // version of this code did use a unified method which was harder to 1034 // follow and, as a result, it had subtle bugs that were hard to 1035 // track down. So keeping these two methods separate allows each to 1036 // be more readable. It will be good to keep these two in sync as 1037 // much as possible. 1038 1039 assert_heap_not_locked_and_not_at_safepoint(); 1040 assert(isHumongous(word_size), "attempt_allocation_humongous() " 1041 "should only be called for humongous allocations"); 1042 1043 // Humongous objects can exhaust the heap quickly, so we should check if we 1044 // need to start a marking cycle at each humongous object allocation. We do 1045 // the check before we do the actual allocation. The reason for doing it 1046 // before the allocation is that we avoid having to keep track of the newly 1047 // allocated memory while we do a GC. 1048 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation", 1049 word_size)) { 1050 collect(GCCause::_g1_humongous_allocation); 1051 } 1052 1053 // We will loop until a) we manage to successfully perform the 1054 // allocation or b) we successfully schedule a collection which 1055 // fails to perform the allocation. b) is the only case when we'll 1056 // return NULL. 1057 HeapWord* result = NULL; 1058 for (int try_count = 1; /* we'll return */; try_count += 1) { 1059 bool should_try_gc; 1060 unsigned int gc_count_before; 1061 1062 { 1063 MutexLockerEx x(Heap_lock); 1064 1065 // Given that humongous objects are not allocated in young 1066 // regions, we'll first try to do the allocation without doing a 1067 // collection hoping that there's enough space in the heap. 1068 result = humongous_obj_allocate(word_size); 1069 if (result != NULL) { 1070 return result; 1071 } 1072 1073 if (GC_locker::is_active_and_needs_gc()) { 1074 should_try_gc = false; 1075 } else { 1076 // The GCLocker may not be active but the GCLocker initiated 1077 // GC may not yet have been performed (GCLocker::needs_gc() 1078 // returns true). In this case we do not try this GC and 1079 // wait until the GCLocker initiated GC is performed, and 1080 // then retry the allocation. 1081 if (GC_locker::needs_gc()) { 1082 should_try_gc = false; 1083 } else { 1084 // Read the GC count while still holding the Heap_lock. 1085 gc_count_before = total_collections(); 1086 should_try_gc = true; 1087 } 1088 } 1089 } 1090 1091 if (should_try_gc) { 1092 // If we failed to allocate the humongous object, we should try to 1093 // do a collection pause (if we're allowed) in case it reclaims 1094 // enough space for the allocation to succeed after the pause. 1095 1096 bool succeeded; 1097 result = do_collection_pause(word_size, gc_count_before, &succeeded, 1098 GCCause::_g1_humongous_allocation); 1099 if (result != NULL) { 1100 assert(succeeded, "only way to get back a non-NULL result"); 1101 return result; 1102 } 1103 1104 if (succeeded) { 1105 // If we get here we successfully scheduled a collection which 1106 // failed to allocate. No point in trying to allocate 1107 // further. We'll just return NULL. 1108 MutexLockerEx x(Heap_lock); 1109 *gc_count_before_ret = total_collections(); 1110 return NULL; 1111 } 1112 } else { 1113 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { 1114 MutexLockerEx x(Heap_lock); 1115 *gc_count_before_ret = total_collections(); 1116 return NULL; 1117 } 1118 // The GCLocker is either active or the GCLocker initiated 1119 // GC has not yet been performed. Stall until it is and 1120 // then retry the allocation. 1121 GC_locker::stall_until_clear(); 1122 (*gclocker_retry_count_ret) += 1; 1123 } 1124 1125 // We can reach here if we were unsuccessful in scheduling a 1126 // collection (because another thread beat us to it) or if we were 1127 // stalled due to the GC locker. In either can we should retry the 1128 // allocation attempt in case another thread successfully 1129 // performed a collection and reclaimed enough space. Give a 1130 // warning if we seem to be looping forever. 1131 1132 if ((QueuedAllocationWarningCount > 0) && 1133 (try_count % QueuedAllocationWarningCount == 0)) { 1134 warning("G1CollectedHeap::attempt_allocation_humongous() " 1135 "retries %d times", try_count); 1136 } 1137 } 1138 1139 ShouldNotReachHere(); 1140 return NULL; 1141 } 1142 1143 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size, 1144 bool expect_null_mutator_alloc_region) { 1145 assert_at_safepoint(true /* should_be_vm_thread */); 1146 assert(_mutator_alloc_region.get() == NULL || 1147 !expect_null_mutator_alloc_region, 1148 "the current alloc region was unexpectedly found to be non-NULL"); 1149 1150 if (!isHumongous(word_size)) { 1151 return _mutator_alloc_region.attempt_allocation_locked(word_size, 1152 false /* bot_updates */); 1153 } else { 1154 HeapWord* result = humongous_obj_allocate(word_size); 1155 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) { 1156 g1_policy()->set_initiate_conc_mark_if_possible(); 1157 } 1158 return result; 1159 } 1160 1161 ShouldNotReachHere(); 1162 } 1163 1164 class PostMCRemSetClearClosure: public HeapRegionClosure { 1165 G1CollectedHeap* _g1h; 1166 ModRefBarrierSet* _mr_bs; 1167 public: 1168 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) : 1169 _g1h(g1h), _mr_bs(mr_bs) {} 1170 1171 bool doHeapRegion(HeapRegion* r) { 1172 HeapRegionRemSet* hrrs = r->rem_set(); 1173 1174 if (r->continuesHumongous()) { 1175 // We'll assert that the strong code root list and RSet is empty 1176 assert(hrrs->strong_code_roots_list_length() == 0, "sanity"); 1177 assert(hrrs->occupied() == 0, "RSet should be empty"); 1178 return false; 1179 } 1180 1181 _g1h->reset_gc_time_stamps(r); 1182 hrrs->clear(); 1183 // You might think here that we could clear just the cards 1184 // corresponding to the used region. But no: if we leave a dirty card 1185 // in a region we might allocate into, then it would prevent that card 1186 // from being enqueued, and cause it to be missed. 1187 // Re: the performance cost: we shouldn't be doing full GC anyway! 1188 _mr_bs->clear(MemRegion(r->bottom(), r->end())); 1189 1190 return false; 1191 } 1192 }; 1193 1194 void G1CollectedHeap::clear_rsets_post_compaction() { 1195 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set()); 1196 heap_region_iterate(&rs_clear); 1197 } 1198 1199 class RebuildRSOutOfRegionClosure: public HeapRegionClosure { 1200 G1CollectedHeap* _g1h; 1201 UpdateRSOopClosure _cl; 1202 int _worker_i; 1203 public: 1204 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) : 1205 _cl(g1->g1_rem_set(), worker_i), 1206 _worker_i(worker_i), 1207 _g1h(g1) 1208 { } 1209 1210 bool doHeapRegion(HeapRegion* r) { 1211 if (!r->continuesHumongous()) { 1212 _cl.set_from(r); 1213 r->oop_iterate(&_cl); 1214 } 1215 return false; 1216 } 1217 }; 1218 1219 class ParRebuildRSTask: public AbstractGangTask { 1220 G1CollectedHeap* _g1; 1221 public: 1222 ParRebuildRSTask(G1CollectedHeap* g1) 1223 : AbstractGangTask("ParRebuildRSTask"), 1224 _g1(g1) 1225 { } 1226 1227 void work(uint worker_id) { 1228 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id); 1229 _g1->heap_region_par_iterate_chunked(&rebuild_rs, worker_id, 1230 _g1->workers()->active_workers(), 1231 HeapRegion::RebuildRSClaimValue); 1232 } 1233 }; 1234 1235 class PostCompactionPrinterClosure: public HeapRegionClosure { 1236 private: 1237 G1HRPrinter* _hr_printer; 1238 public: 1239 bool doHeapRegion(HeapRegion* hr) { 1240 assert(!hr->is_young(), "not expecting to find young regions"); 1241 // We only generate output for non-empty regions. 1242 if (!hr->is_empty()) { 1243 if (!hr->isHumongous()) { 1244 _hr_printer->post_compaction(hr, G1HRPrinter::Old); 1245 } else if (hr->startsHumongous()) { 1246 if (hr->region_num() == 1) { 1247 // single humongous region 1248 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous); 1249 } else { 1250 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous); 1251 } 1252 } else { 1253 assert(hr->continuesHumongous(), "only way to get here"); 1254 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous); 1255 } 1256 } 1257 return false; 1258 } 1259 1260 PostCompactionPrinterClosure(G1HRPrinter* hr_printer) 1261 : _hr_printer(hr_printer) { } 1262 }; 1263 1264 void G1CollectedHeap::print_hrs_post_compaction() { 1265 PostCompactionPrinterClosure cl(hr_printer()); 1266 heap_region_iterate(&cl); 1267 } 1268 1269 bool G1CollectedHeap::do_collection(bool explicit_gc, 1270 bool clear_all_soft_refs, 1271 size_t word_size) { 1272 assert_at_safepoint(true /* should_be_vm_thread */); 1273 1274 if (GC_locker::check_active_before_gc()) { 1275 return false; 1276 } 1277 1278 STWGCTimer* gc_timer = G1MarkSweep::gc_timer(); 1279 gc_timer->register_gc_start(); 1280 1281 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer(); 1282 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start()); 1283 1284 SvcGCMarker sgcm(SvcGCMarker::FULL); 1285 ResourceMark rm; 1286 1287 print_heap_before_gc(); 1288 trace_heap_before_gc(gc_tracer); 1289 1290 size_t metadata_prev_used = MetaspaceAux::used_bytes(); 1291 1292 verify_region_sets_optional(); 1293 1294 const bool do_clear_all_soft_refs = clear_all_soft_refs || 1295 collector_policy()->should_clear_all_soft_refs(); 1296 1297 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy()); 1298 1299 { 1300 IsGCActiveMark x; 1301 1302 // Timing 1303 assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant"); 1304 gclog_or_tty->date_stamp(G1Log::fine() && PrintGCDateStamps); 1305 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty); 1306 1307 { 1308 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL, gc_tracer->gc_id()); 1309 TraceCollectorStats tcs(g1mm()->full_collection_counters()); 1310 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause()); 1311 1312 double start = os::elapsedTime(); 1313 g1_policy()->record_full_collection_start(); 1314 1315 // Note: When we have a more flexible GC logging framework that 1316 // allows us to add optional attributes to a GC log record we 1317 // could consider timing and reporting how long we wait in the 1318 // following two methods. 1319 wait_while_free_regions_coming(); 1320 // If we start the compaction before the CM threads finish 1321 // scanning the root regions we might trip them over as we'll 1322 // be moving objects / updating references. So let's wait until 1323 // they are done. By telling them to abort, they should complete 1324 // early. 1325 _cm->root_regions()->abort(); 1326 _cm->root_regions()->wait_until_scan_finished(); 1327 append_secondary_free_list_if_not_empty_with_lock(); 1328 1329 gc_prologue(true); 1330 increment_total_collections(true /* full gc */); 1331 increment_old_marking_cycles_started(); 1332 1333 assert(used() == recalculate_used(), "Should be equal"); 1334 1335 verify_before_gc(); 1336 1337 pre_full_gc_dump(gc_timer); 1338 1339 COMPILER2_PRESENT(DerivedPointerTable::clear()); 1340 1341 // Disable discovery and empty the discovered lists 1342 // for the CM ref processor. 1343 ref_processor_cm()->disable_discovery(); 1344 ref_processor_cm()->abandon_partial_discovery(); 1345 ref_processor_cm()->verify_no_references_recorded(); 1346 1347 // Abandon current iterations of concurrent marking and concurrent 1348 // refinement, if any are in progress. We have to do this before 1349 // wait_until_scan_finished() below. 1350 concurrent_mark()->abort(); 1351 1352 // Make sure we'll choose a new allocation region afterwards. 1353 release_mutator_alloc_region(); 1354 abandon_gc_alloc_regions(); 1355 g1_rem_set()->cleanupHRRS(); 1356 1357 // We should call this after we retire any currently active alloc 1358 // regions so that all the ALLOC / RETIRE events are generated 1359 // before the start GC event. 1360 _hr_printer.start_gc(true /* full */, (size_t) total_collections()); 1361 1362 // We may have added regions to the current incremental collection 1363 // set between the last GC or pause and now. We need to clear the 1364 // incremental collection set and then start rebuilding it afresh 1365 // after this full GC. 1366 abandon_collection_set(g1_policy()->inc_cset_head()); 1367 g1_policy()->clear_incremental_cset(); 1368 g1_policy()->stop_incremental_cset_building(); 1369 1370 tear_down_region_sets(false /* free_list_only */); 1371 g1_policy()->set_gcs_are_young(true); 1372 1373 // See the comments in g1CollectedHeap.hpp and 1374 // G1CollectedHeap::ref_processing_init() about 1375 // how reference processing currently works in G1. 1376 1377 // Temporarily make discovery by the STW ref processor single threaded (non-MT). 1378 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false); 1379 1380 // Temporarily clear the STW ref processor's _is_alive_non_header field. 1381 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL); 1382 1383 ref_processor_stw()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/); 1384 ref_processor_stw()->setup_policy(do_clear_all_soft_refs); 1385 1386 // Do collection work 1387 { 1388 HandleMark hm; // Discard invalid handles created during gc 1389 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs); 1390 } 1391 1392 assert(free_regions() == 0, "we should not have added any free regions"); 1393 rebuild_region_sets(false /* free_list_only */); 1394 1395 // Enqueue any discovered reference objects that have 1396 // not been removed from the discovered lists. 1397 ref_processor_stw()->enqueue_discovered_references(); 1398 1399 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 1400 1401 MemoryService::track_memory_usage(); 1402 1403 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 1404 ref_processor_stw()->verify_no_references_recorded(); 1405 1406 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 1407 ClassLoaderDataGraph::purge(); 1408 MetaspaceAux::verify_metrics(); 1409 1410 // Note: since we've just done a full GC, concurrent 1411 // marking is no longer active. Therefore we need not 1412 // re-enable reference discovery for the CM ref processor. 1413 // That will be done at the start of the next marking cycle. 1414 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition"); 1415 ref_processor_cm()->verify_no_references_recorded(); 1416 1417 reset_gc_time_stamp(); 1418 // Since everything potentially moved, we will clear all remembered 1419 // sets, and clear all cards. Later we will rebuild remembered 1420 // sets. We will also reset the GC time stamps of the regions. 1421 clear_rsets_post_compaction(); 1422 check_gc_time_stamps(); 1423 1424 // Resize the heap if necessary. 1425 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size); 1426 1427 if (_hr_printer.is_active()) { 1428 // We should do this after we potentially resize the heap so 1429 // that all the COMMIT / UNCOMMIT events are generated before 1430 // the end GC event. 1431 1432 print_hrs_post_compaction(); 1433 _hr_printer.end_gc(true /* full */, (size_t) total_collections()); 1434 } 1435 1436 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 1437 if (hot_card_cache->use_cache()) { 1438 hot_card_cache->reset_card_counts(); 1439 hot_card_cache->reset_hot_cache(); 1440 } 1441 1442 // Rebuild remembered sets of all regions. 1443 if (G1CollectedHeap::use_parallel_gc_threads()) { 1444 uint n_workers = 1445 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 1446 workers()->active_workers(), 1447 Threads::number_of_non_daemon_threads()); 1448 assert(UseDynamicNumberOfGCThreads || 1449 n_workers == workers()->total_workers(), 1450 "If not dynamic should be using all the workers"); 1451 workers()->set_active_workers(n_workers); 1452 // Set parallel threads in the heap (_n_par_threads) only 1453 // before a parallel phase and always reset it to 0 after 1454 // the phase so that the number of parallel threads does 1455 // no get carried forward to a serial phase where there 1456 // may be code that is "possibly_parallel". 1457 set_par_threads(n_workers); 1458 1459 ParRebuildRSTask rebuild_rs_task(this); 1460 assert(check_heap_region_claim_values( 1461 HeapRegion::InitialClaimValue), "sanity check"); 1462 assert(UseDynamicNumberOfGCThreads || 1463 workers()->active_workers() == workers()->total_workers(), 1464 "Unless dynamic should use total workers"); 1465 // Use the most recent number of active workers 1466 assert(workers()->active_workers() > 0, 1467 "Active workers not properly set"); 1468 set_par_threads(workers()->active_workers()); 1469 workers()->run_task(&rebuild_rs_task); 1470 set_par_threads(0); 1471 assert(check_heap_region_claim_values( 1472 HeapRegion::RebuildRSClaimValue), "sanity check"); 1473 reset_heap_region_claim_values(); 1474 } else { 1475 RebuildRSOutOfRegionClosure rebuild_rs(this); 1476 heap_region_iterate(&rebuild_rs); 1477 } 1478 1479 // Rebuild the strong code root lists for each region 1480 rebuild_strong_code_roots(); 1481 1482 if (true) { // FIXME 1483 MetaspaceGC::compute_new_size(); 1484 } 1485 1486 #ifdef TRACESPINNING 1487 ParallelTaskTerminator::print_termination_counts(); 1488 #endif 1489 1490 // Discard all rset updates 1491 JavaThread::dirty_card_queue_set().abandon_logs(); 1492 assert(!G1DeferredRSUpdate 1493 || (G1DeferredRSUpdate && 1494 (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any"); 1495 1496 _young_list->reset_sampled_info(); 1497 // At this point there should be no regions in the 1498 // entire heap tagged as young. 1499 assert(check_young_list_empty(true /* check_heap */), 1500 "young list should be empty at this point"); 1501 1502 // Update the number of full collections that have been completed. 1503 increment_old_marking_cycles_completed(false /* concurrent */); 1504 1505 _hrs.verify_optional(); 1506 verify_region_sets_optional(); 1507 1508 verify_after_gc(); 1509 1510 // Start a new incremental collection set for the next pause 1511 assert(g1_policy()->collection_set() == NULL, "must be"); 1512 g1_policy()->start_incremental_cset_building(); 1513 1514 clear_cset_fast_test(); 1515 1516 init_mutator_alloc_region(); 1517 1518 double end = os::elapsedTime(); 1519 g1_policy()->record_full_collection_end(); 1520 1521 if (G1Log::fine()) { 1522 g1_policy()->print_heap_transition(); 1523 } 1524 1525 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 1526 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 1527 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 1528 // before any GC notifications are raised. 1529 g1mm()->update_sizes(); 1530 1531 gc_epilogue(true); 1532 } 1533 1534 if (G1Log::finer()) { 1535 g1_policy()->print_detailed_heap_transition(true /* full */); 1536 } 1537 1538 print_heap_after_gc(); 1539 trace_heap_after_gc(gc_tracer); 1540 1541 post_full_gc_dump(gc_timer); 1542 1543 gc_timer->register_gc_end(); 1544 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions()); 1545 } 1546 1547 return true; 1548 } 1549 1550 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) { 1551 // do_collection() will return whether it succeeded in performing 1552 // the GC. Currently, there is no facility on the 1553 // do_full_collection() API to notify the caller than the collection 1554 // did not succeed (e.g., because it was locked out by the GC 1555 // locker). So, right now, we'll ignore the return value. 1556 bool dummy = do_collection(true, /* explicit_gc */ 1557 clear_all_soft_refs, 1558 0 /* word_size */); 1559 } 1560 1561 // This code is mostly copied from TenuredGeneration. 1562 void 1563 G1CollectedHeap:: 1564 resize_if_necessary_after_full_collection(size_t word_size) { 1565 // Include the current allocation, if any, and bytes that will be 1566 // pre-allocated to support collections, as "used". 1567 const size_t used_after_gc = used(); 1568 const size_t capacity_after_gc = capacity(); 1569 const size_t free_after_gc = capacity_after_gc - used_after_gc; 1570 1571 // This is enforced in arguments.cpp. 1572 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, 1573 "otherwise the code below doesn't make sense"); 1574 1575 // We don't have floating point command-line arguments 1576 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0; 1577 const double maximum_used_percentage = 1.0 - minimum_free_percentage; 1578 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0; 1579 const double minimum_used_percentage = 1.0 - maximum_free_percentage; 1580 1581 const size_t min_heap_size = collector_policy()->min_heap_byte_size(); 1582 const size_t max_heap_size = collector_policy()->max_heap_byte_size(); 1583 1584 // We have to be careful here as these two calculations can overflow 1585 // 32-bit size_t's. 1586 double used_after_gc_d = (double) used_after_gc; 1587 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage; 1588 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage; 1589 1590 // Let's make sure that they are both under the max heap size, which 1591 // by default will make them fit into a size_t. 1592 double desired_capacity_upper_bound = (double) max_heap_size; 1593 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d, 1594 desired_capacity_upper_bound); 1595 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d, 1596 desired_capacity_upper_bound); 1597 1598 // We can now safely turn them into size_t's. 1599 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d; 1600 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d; 1601 1602 // This assert only makes sense here, before we adjust them 1603 // with respect to the min and max heap size. 1604 assert(minimum_desired_capacity <= maximum_desired_capacity, 1605 err_msg("minimum_desired_capacity = "SIZE_FORMAT", " 1606 "maximum_desired_capacity = "SIZE_FORMAT, 1607 minimum_desired_capacity, maximum_desired_capacity)); 1608 1609 // Should not be greater than the heap max size. No need to adjust 1610 // it with respect to the heap min size as it's a lower bound (i.e., 1611 // we'll try to make the capacity larger than it, not smaller). 1612 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size); 1613 // Should not be less than the heap min size. No need to adjust it 1614 // with respect to the heap max size as it's an upper bound (i.e., 1615 // we'll try to make the capacity smaller than it, not greater). 1616 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size); 1617 1618 if (capacity_after_gc < minimum_desired_capacity) { 1619 // Don't expand unless it's significant 1620 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc; 1621 ergo_verbose4(ErgoHeapSizing, 1622 "attempt heap expansion", 1623 ergo_format_reason("capacity lower than " 1624 "min desired capacity after Full GC") 1625 ergo_format_byte("capacity") 1626 ergo_format_byte("occupancy") 1627 ergo_format_byte_perc("min desired capacity"), 1628 capacity_after_gc, used_after_gc, 1629 minimum_desired_capacity, (double) MinHeapFreeRatio); 1630 expand(expand_bytes); 1631 1632 // No expansion, now see if we want to shrink 1633 } else if (capacity_after_gc > maximum_desired_capacity) { 1634 // Capacity too large, compute shrinking size 1635 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity; 1636 ergo_verbose4(ErgoHeapSizing, 1637 "attempt heap shrinking", 1638 ergo_format_reason("capacity higher than " 1639 "max desired capacity after Full GC") 1640 ergo_format_byte("capacity") 1641 ergo_format_byte("occupancy") 1642 ergo_format_byte_perc("max desired capacity"), 1643 capacity_after_gc, used_after_gc, 1644 maximum_desired_capacity, (double) MaxHeapFreeRatio); 1645 shrink(shrink_bytes); 1646 } 1647 } 1648 1649 1650 HeapWord* 1651 G1CollectedHeap::satisfy_failed_allocation(size_t word_size, 1652 bool* succeeded) { 1653 assert_at_safepoint(true /* should_be_vm_thread */); 1654 1655 *succeeded = true; 1656 // Let's attempt the allocation first. 1657 HeapWord* result = 1658 attempt_allocation_at_safepoint(word_size, 1659 false /* expect_null_mutator_alloc_region */); 1660 if (result != NULL) { 1661 assert(*succeeded, "sanity"); 1662 return result; 1663 } 1664 1665 // In a G1 heap, we're supposed to keep allocation from failing by 1666 // incremental pauses. Therefore, at least for now, we'll favor 1667 // expansion over collection. (This might change in the future if we can 1668 // do something smarter than full collection to satisfy a failed alloc.) 1669 result = expand_and_allocate(word_size); 1670 if (result != NULL) { 1671 assert(*succeeded, "sanity"); 1672 return result; 1673 } 1674 1675 // Expansion didn't work, we'll try to do a Full GC. 1676 bool gc_succeeded = do_collection(false, /* explicit_gc */ 1677 false, /* clear_all_soft_refs */ 1678 word_size); 1679 if (!gc_succeeded) { 1680 *succeeded = false; 1681 return NULL; 1682 } 1683 1684 // Retry the allocation 1685 result = attempt_allocation_at_safepoint(word_size, 1686 true /* expect_null_mutator_alloc_region */); 1687 if (result != NULL) { 1688 assert(*succeeded, "sanity"); 1689 return result; 1690 } 1691 1692 // Then, try a Full GC that will collect all soft references. 1693 gc_succeeded = do_collection(false, /* explicit_gc */ 1694 true, /* clear_all_soft_refs */ 1695 word_size); 1696 if (!gc_succeeded) { 1697 *succeeded = false; 1698 return NULL; 1699 } 1700 1701 // Retry the allocation once more 1702 result = attempt_allocation_at_safepoint(word_size, 1703 true /* expect_null_mutator_alloc_region */); 1704 if (result != NULL) { 1705 assert(*succeeded, "sanity"); 1706 return result; 1707 } 1708 1709 assert(!collector_policy()->should_clear_all_soft_refs(), 1710 "Flag should have been handled and cleared prior to this point"); 1711 1712 // What else? We might try synchronous finalization later. If the total 1713 // space available is large enough for the allocation, then a more 1714 // complete compaction phase than we've tried so far might be 1715 // appropriate. 1716 assert(*succeeded, "sanity"); 1717 return NULL; 1718 } 1719 1720 // Attempting to expand the heap sufficiently 1721 // to support an allocation of the given "word_size". If 1722 // successful, perform the allocation and return the address of the 1723 // allocated block, or else "NULL". 1724 1725 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) { 1726 assert_at_safepoint(true /* should_be_vm_thread */); 1727 1728 verify_region_sets_optional(); 1729 1730 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes); 1731 ergo_verbose1(ErgoHeapSizing, 1732 "attempt heap expansion", 1733 ergo_format_reason("allocation request failed") 1734 ergo_format_byte("allocation request"), 1735 word_size * HeapWordSize); 1736 if (expand(expand_bytes)) { 1737 _hrs.verify_optional(); 1738 verify_region_sets_optional(); 1739 return attempt_allocation_at_safepoint(word_size, 1740 false /* expect_null_mutator_alloc_region */); 1741 } 1742 return NULL; 1743 } 1744 1745 void G1CollectedHeap::update_committed_space(HeapWord* old_end, 1746 HeapWord* new_end) { 1747 assert(old_end != new_end, "don't call this otherwise"); 1748 assert((HeapWord*) _g1_storage.high() == new_end, "invariant"); 1749 1750 // Update the committed mem region. 1751 _g1_committed.set_end(new_end); 1752 // Tell the card table about the update. 1753 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed); 1754 // Tell the BOT about the update. 1755 _bot_shared->resize(_g1_committed.word_size()); 1756 // Tell the hot card cache about the update 1757 _cg1r->hot_card_cache()->resize_card_counts(capacity()); 1758 } 1759 1760 bool G1CollectedHeap::expand(size_t expand_bytes) { 1761 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); 1762 aligned_expand_bytes = align_size_up(aligned_expand_bytes, 1763 HeapRegion::GrainBytes); 1764 ergo_verbose2(ErgoHeapSizing, 1765 "expand the heap", 1766 ergo_format_byte("requested expansion amount") 1767 ergo_format_byte("attempted expansion amount"), 1768 expand_bytes, aligned_expand_bytes); 1769 1770 if (_g1_storage.uncommitted_size() == 0) { 1771 ergo_verbose0(ErgoHeapSizing, 1772 "did not expand the heap", 1773 ergo_format_reason("heap already fully expanded")); 1774 return false; 1775 } 1776 1777 // First commit the memory. 1778 HeapWord* old_end = (HeapWord*) _g1_storage.high(); 1779 bool successful = _g1_storage.expand_by(aligned_expand_bytes); 1780 if (successful) { 1781 // Then propagate this update to the necessary data structures. 1782 HeapWord* new_end = (HeapWord*) _g1_storage.high(); 1783 update_committed_space(old_end, new_end); 1784 1785 FreeRegionList expansion_list("Local Expansion List"); 1786 MemRegion mr = _hrs.expand_by(old_end, new_end, &expansion_list); 1787 assert(mr.start() == old_end, "post-condition"); 1788 // mr might be a smaller region than what was requested if 1789 // expand_by() was unable to allocate the HeapRegion instances 1790 assert(mr.end() <= new_end, "post-condition"); 1791 1792 size_t actual_expand_bytes = mr.byte_size(); 1793 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition"); 1794 assert(actual_expand_bytes == expansion_list.total_capacity_bytes(), 1795 "post-condition"); 1796 if (actual_expand_bytes < aligned_expand_bytes) { 1797 // We could not expand _hrs to the desired size. In this case we 1798 // need to shrink the committed space accordingly. 1799 assert(mr.end() < new_end, "invariant"); 1800 1801 size_t diff_bytes = aligned_expand_bytes - actual_expand_bytes; 1802 // First uncommit the memory. 1803 _g1_storage.shrink_by(diff_bytes); 1804 // Then propagate this update to the necessary data structures. 1805 update_committed_space(new_end, mr.end()); 1806 } 1807 _free_list.add_as_tail(&expansion_list); 1808 1809 if (_hr_printer.is_active()) { 1810 HeapWord* curr = mr.start(); 1811 while (curr < mr.end()) { 1812 HeapWord* curr_end = curr + HeapRegion::GrainWords; 1813 _hr_printer.commit(curr, curr_end); 1814 curr = curr_end; 1815 } 1816 assert(curr == mr.end(), "post-condition"); 1817 } 1818 g1_policy()->record_new_heap_size(n_regions()); 1819 } else { 1820 ergo_verbose0(ErgoHeapSizing, 1821 "did not expand the heap", 1822 ergo_format_reason("heap expansion operation failed")); 1823 // The expansion of the virtual storage space was unsuccessful. 1824 // Let's see if it was because we ran out of swap. 1825 if (G1ExitOnExpansionFailure && 1826 _g1_storage.uncommitted_size() >= aligned_expand_bytes) { 1827 // We had head room... 1828 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion"); 1829 } 1830 } 1831 return successful; 1832 } 1833 1834 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) { 1835 size_t aligned_shrink_bytes = 1836 ReservedSpace::page_align_size_down(shrink_bytes); 1837 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes, 1838 HeapRegion::GrainBytes); 1839 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes); 1840 1841 uint num_regions_removed = _hrs.shrink_by(num_regions_to_remove); 1842 HeapWord* old_end = (HeapWord*) _g1_storage.high(); 1843 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes; 1844 1845 ergo_verbose3(ErgoHeapSizing, 1846 "shrink the heap", 1847 ergo_format_byte("requested shrinking amount") 1848 ergo_format_byte("aligned shrinking amount") 1849 ergo_format_byte("attempted shrinking amount"), 1850 shrink_bytes, aligned_shrink_bytes, shrunk_bytes); 1851 if (num_regions_removed > 0) { 1852 _g1_storage.shrink_by(shrunk_bytes); 1853 HeapWord* new_end = (HeapWord*) _g1_storage.high(); 1854 1855 if (_hr_printer.is_active()) { 1856 HeapWord* curr = old_end; 1857 while (curr > new_end) { 1858 HeapWord* curr_end = curr; 1859 curr -= HeapRegion::GrainWords; 1860 _hr_printer.uncommit(curr, curr_end); 1861 } 1862 } 1863 1864 _expansion_regions += num_regions_removed; 1865 update_committed_space(old_end, new_end); 1866 HeapRegionRemSet::shrink_heap(n_regions()); 1867 g1_policy()->record_new_heap_size(n_regions()); 1868 } else { 1869 ergo_verbose0(ErgoHeapSizing, 1870 "did not shrink the heap", 1871 ergo_format_reason("heap shrinking operation failed")); 1872 } 1873 } 1874 1875 void G1CollectedHeap::shrink(size_t shrink_bytes) { 1876 verify_region_sets_optional(); 1877 1878 // We should only reach here at the end of a Full GC which means we 1879 // should not not be holding to any GC alloc regions. The method 1880 // below will make sure of that and do any remaining clean up. 1881 abandon_gc_alloc_regions(); 1882 1883 // Instead of tearing down / rebuilding the free lists here, we 1884 // could instead use the remove_all_pending() method on free_list to 1885 // remove only the ones that we need to remove. 1886 tear_down_region_sets(true /* free_list_only */); 1887 shrink_helper(shrink_bytes); 1888 rebuild_region_sets(true /* free_list_only */); 1889 1890 _hrs.verify_optional(); 1891 verify_region_sets_optional(); 1892 } 1893 1894 // Public methods. 1895 1896 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away 1897 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list 1898 #endif // _MSC_VER 1899 1900 1901 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) : 1902 SharedHeap(policy_), 1903 _g1_policy(policy_), 1904 _dirty_card_queue_set(false), 1905 _into_cset_dirty_card_queue_set(false), 1906 _is_alive_closure_cm(this), 1907 _is_alive_closure_stw(this), 1908 _ref_processor_cm(NULL), 1909 _ref_processor_stw(NULL), 1910 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)), 1911 _bot_shared(NULL), 1912 _evac_failure_scan_stack(NULL), 1913 _mark_in_progress(false), 1914 _cg1r(NULL), _summary_bytes_used(0), 1915 _g1mm(NULL), 1916 _refine_cte_cl(NULL), 1917 _full_collection(false), 1918 _free_list("Master Free List", new MasterFreeRegionListMtSafeChecker()), 1919 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()), 1920 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()), 1921 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()), 1922 _free_regions_coming(false), 1923 _young_list(new YoungList(this)), 1924 _gc_time_stamp(0), 1925 _retained_old_gc_alloc_region(NULL), 1926 _survivor_plab_stats(YoungPLABSize, PLABWeight), 1927 _old_plab_stats(OldPLABSize, PLABWeight), 1928 _expand_heap_after_alloc_failure(true), 1929 _surviving_young_words(NULL), 1930 _old_marking_cycles_started(0), 1931 _old_marking_cycles_completed(0), 1932 _concurrent_cycle_started(false), 1933 _in_cset_fast_test(), 1934 _dirty_cards_region_list(NULL), 1935 _worker_cset_start_region(NULL), 1936 _worker_cset_start_region_time_stamp(NULL), 1937 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()), 1938 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()), 1939 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()), 1940 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) { 1941 1942 _g1h = this; 1943 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) { 1944 vm_exit_during_initialization("Failed necessary allocation."); 1945 } 1946 1947 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2; 1948 1949 int n_queues = MAX2((int)ParallelGCThreads, 1); 1950 _task_queues = new RefToScanQueueSet(n_queues); 1951 1952 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets(); 1953 assert(n_rem_sets > 0, "Invariant."); 1954 1955 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC); 1956 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(unsigned int, n_queues, mtGC); 1957 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC); 1958 1959 for (int i = 0; i < n_queues; i++) { 1960 RefToScanQueue* q = new RefToScanQueue(); 1961 q->initialize(); 1962 _task_queues->register_queue(i, q); 1963 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo(); 1964 } 1965 clear_cset_start_regions(); 1966 1967 // Initialize the G1EvacuationFailureALot counters and flags. 1968 NOT_PRODUCT(reset_evacuation_should_fail();) 1969 1970 guarantee(_task_queues != NULL, "task_queues allocation failure."); 1971 } 1972 1973 jint G1CollectedHeap::initialize() { 1974 CollectedHeap::pre_initialize(); 1975 os::enable_vtime(); 1976 1977 G1Log::init(); 1978 1979 // Necessary to satisfy locking discipline assertions. 1980 1981 MutexLocker x(Heap_lock); 1982 1983 // We have to initialize the printer before committing the heap, as 1984 // it will be used then. 1985 _hr_printer.set_active(G1PrintHeapRegions); 1986 1987 // While there are no constraints in the GC code that HeapWordSize 1988 // be any particular value, there are multiple other areas in the 1989 // system which believe this to be true (e.g. oop->object_size in some 1990 // cases incorrectly returns the size in wordSize units rather than 1991 // HeapWordSize). 1992 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 1993 1994 size_t init_byte_size = collector_policy()->initial_heap_byte_size(); 1995 size_t max_byte_size = collector_policy()->max_heap_byte_size(); 1996 size_t heap_alignment = collector_policy()->heap_alignment(); 1997 1998 // Ensure that the sizes are properly aligned. 1999 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap"); 2000 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap"); 2001 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap"); 2002 2003 _cg1r = new ConcurrentG1Refine(this); 2004 2005 // Reserve the maximum. 2006 2007 // When compressed oops are enabled, the preferred heap base 2008 // is calculated by subtracting the requested size from the 2009 // 32Gb boundary and using the result as the base address for 2010 // heap reservation. If the requested size is not aligned to 2011 // HeapRegion::GrainBytes (i.e. the alignment that is passed 2012 // into the ReservedHeapSpace constructor) then the actual 2013 // base of the reserved heap may end up differing from the 2014 // address that was requested (i.e. the preferred heap base). 2015 // If this happens then we could end up using a non-optimal 2016 // compressed oops mode. 2017 2018 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size, 2019 heap_alignment); 2020 2021 // It is important to do this in a way such that concurrent readers can't 2022 // temporarily think something is in the heap. (I've actually seen this 2023 // happen in asserts: DLD.) 2024 _reserved.set_word_size(0); 2025 _reserved.set_start((HeapWord*)heap_rs.base()); 2026 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size())); 2027 2028 _expansion_regions = (uint) (max_byte_size / HeapRegion::GrainBytes); 2029 2030 // Create the gen rem set (and barrier set) for the entire reserved region. 2031 _rem_set = collector_policy()->create_rem_set(_reserved, 2); 2032 set_barrier_set(rem_set()->bs()); 2033 if (!barrier_set()->is_a(BarrierSet::G1SATBCTLogging)) { 2034 vm_exit_during_initialization("G1 requires a G1SATBLoggingCardTableModRefBS"); 2035 return JNI_ENOMEM; 2036 } 2037 2038 // Also create a G1 rem set. 2039 _g1_rem_set = new G1RemSet(this, g1_barrier_set()); 2040 2041 // Carve out the G1 part of the heap. 2042 2043 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size); 2044 _g1_reserved = MemRegion((HeapWord*)g1_rs.base(), 2045 g1_rs.size()/HeapWordSize); 2046 2047 _g1_storage.initialize(g1_rs, 0); 2048 _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0); 2049 _hrs.initialize((HeapWord*) _g1_reserved.start(), 2050 (HeapWord*) _g1_reserved.end()); 2051 assert(_hrs.max_length() == _expansion_regions, 2052 err_msg("max length: %u expansion regions: %u", 2053 _hrs.max_length(), _expansion_regions)); 2054 2055 // Do later initialization work for concurrent refinement. 2056 _cg1r->init(); 2057 2058 // 6843694 - ensure that the maximum region index can fit 2059 // in the remembered set structures. 2060 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; 2061 guarantee((max_regions() - 1) <= max_region_idx, "too many regions"); 2062 2063 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; 2064 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); 2065 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region, 2066 "too many cards per region"); 2067 2068 FreeRegionList::set_unrealistically_long_length(max_regions() + 1); 2069 2070 _bot_shared = new G1BlockOffsetSharedArray(_reserved, 2071 heap_word_size(init_byte_size)); 2072 2073 _g1h = this; 2074 2075 _in_cset_fast_test.initialize(_g1_reserved.start(), _g1_reserved.end(), HeapRegion::GrainBytes); 2076 2077 // Create the ConcurrentMark data structure and thread. 2078 // (Must do this late, so that "max_regions" is defined.) 2079 _cm = new ConcurrentMark(this, heap_rs); 2080 if (_cm == NULL || !_cm->completed_initialization()) { 2081 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark"); 2082 return JNI_ENOMEM; 2083 } 2084 _cmThread = _cm->cmThread(); 2085 2086 // Initialize the from_card cache structure of HeapRegionRemSet. 2087 HeapRegionRemSet::init_heap(max_regions()); 2088 2089 // Now expand into the initial heap size. 2090 if (!expand(init_byte_size)) { 2091 vm_shutdown_during_initialization("Failed to allocate initial heap."); 2092 return JNI_ENOMEM; 2093 } 2094 2095 // Perform any initialization actions delegated to the policy. 2096 g1_policy()->init(); 2097 2098 _refine_cte_cl = 2099 new RefineCardTableEntryClosure(g1_rem_set(), 2100 concurrent_g1_refine()); 2101 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl); 2102 2103 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon, 2104 SATB_Q_FL_lock, 2105 G1SATBProcessCompletedThreshold, 2106 Shared_SATB_Q_lock); 2107 2108 JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon, 2109 DirtyCardQ_FL_lock, 2110 concurrent_g1_refine()->yellow_zone(), 2111 concurrent_g1_refine()->red_zone(), 2112 Shared_DirtyCardQ_lock); 2113 2114 if (G1DeferredRSUpdate) { 2115 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon, 2116 DirtyCardQ_FL_lock, 2117 -1, // never trigger processing 2118 -1, // no limit on length 2119 Shared_DirtyCardQ_lock, 2120 &JavaThread::dirty_card_queue_set()); 2121 } 2122 2123 // Initialize the card queue set used to hold cards containing 2124 // references into the collection set. 2125 _into_cset_dirty_card_queue_set.initialize(DirtyCardQ_CBL_mon, 2126 DirtyCardQ_FL_lock, 2127 -1, // never trigger processing 2128 -1, // no limit on length 2129 Shared_DirtyCardQ_lock, 2130 &JavaThread::dirty_card_queue_set()); 2131 2132 // In case we're keeping closure specialization stats, initialize those 2133 // counts and that mechanism. 2134 SpecializationStats::clear(); 2135 2136 // Here we allocate the dummy full region that is required by the 2137 // G1AllocRegion class. If we don't pass an address in the reserved 2138 // space here, lots of asserts fire. 2139 2140 HeapRegion* dummy_region = new_heap_region(0 /* index of bottom region */, 2141 _g1_reserved.start()); 2142 // We'll re-use the same region whether the alloc region will 2143 // require BOT updates or not and, if it doesn't, then a non-young 2144 // region will complain that it cannot support allocations without 2145 // BOT updates. So we'll tag the dummy region as young to avoid that. 2146 dummy_region->set_young(); 2147 // Make sure it's full. 2148 dummy_region->set_top(dummy_region->end()); 2149 G1AllocRegion::setup(this, dummy_region); 2150 2151 init_mutator_alloc_region(); 2152 2153 // Do create of the monitoring and management support so that 2154 // values in the heap have been properly initialized. 2155 _g1mm = new G1MonitoringSupport(this); 2156 2157 G1StringDedup::initialize(); 2158 2159 return JNI_OK; 2160 } 2161 2162 void G1CollectedHeap::stop() { 2163 // Stop all concurrent threads. We do this to make sure these threads 2164 // do not continue to execute and access resources (e.g. gclog_or_tty) 2165 // that are destroyed during shutdown. 2166 _cg1r->stop(); 2167 _cmThread->stop(); 2168 if (G1StringDedup::is_enabled()) { 2169 G1StringDedup::stop(); 2170 } 2171 } 2172 2173 size_t G1CollectedHeap::conservative_max_heap_alignment() { 2174 return HeapRegion::max_region_size(); 2175 } 2176 2177 void G1CollectedHeap::ref_processing_init() { 2178 // Reference processing in G1 currently works as follows: 2179 // 2180 // * There are two reference processor instances. One is 2181 // used to record and process discovered references 2182 // during concurrent marking; the other is used to 2183 // record and process references during STW pauses 2184 // (both full and incremental). 2185 // * Both ref processors need to 'span' the entire heap as 2186 // the regions in the collection set may be dotted around. 2187 // 2188 // * For the concurrent marking ref processor: 2189 // * Reference discovery is enabled at initial marking. 2190 // * Reference discovery is disabled and the discovered 2191 // references processed etc during remarking. 2192 // * Reference discovery is MT (see below). 2193 // * Reference discovery requires a barrier (see below). 2194 // * Reference processing may or may not be MT 2195 // (depending on the value of ParallelRefProcEnabled 2196 // and ParallelGCThreads). 2197 // * A full GC disables reference discovery by the CM 2198 // ref processor and abandons any entries on it's 2199 // discovered lists. 2200 // 2201 // * For the STW processor: 2202 // * Non MT discovery is enabled at the start of a full GC. 2203 // * Processing and enqueueing during a full GC is non-MT. 2204 // * During a full GC, references are processed after marking. 2205 // 2206 // * Discovery (may or may not be MT) is enabled at the start 2207 // of an incremental evacuation pause. 2208 // * References are processed near the end of a STW evacuation pause. 2209 // * For both types of GC: 2210 // * Discovery is atomic - i.e. not concurrent. 2211 // * Reference discovery will not need a barrier. 2212 2213 SharedHeap::ref_processing_init(); 2214 MemRegion mr = reserved_region(); 2215 2216 // Concurrent Mark ref processor 2217 _ref_processor_cm = 2218 new ReferenceProcessor(mr, // span 2219 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2220 // mt processing 2221 (int) ParallelGCThreads, 2222 // degree of mt processing 2223 (ParallelGCThreads > 1) || (ConcGCThreads > 1), 2224 // mt discovery 2225 (int) MAX2(ParallelGCThreads, ConcGCThreads), 2226 // degree of mt discovery 2227 false, 2228 // Reference discovery is not atomic 2229 &_is_alive_closure_cm); 2230 // is alive closure 2231 // (for efficiency/performance) 2232 2233 // STW ref processor 2234 _ref_processor_stw = 2235 new ReferenceProcessor(mr, // span 2236 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2237 // mt processing 2238 MAX2((int)ParallelGCThreads, 1), 2239 // degree of mt processing 2240 (ParallelGCThreads > 1), 2241 // mt discovery 2242 MAX2((int)ParallelGCThreads, 1), 2243 // degree of mt discovery 2244 true, 2245 // Reference discovery is atomic 2246 &_is_alive_closure_stw); 2247 // is alive closure 2248 // (for efficiency/performance) 2249 } 2250 2251 size_t G1CollectedHeap::capacity() const { 2252 return _g1_committed.byte_size(); 2253 } 2254 2255 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) { 2256 assert(!hr->continuesHumongous(), "pre-condition"); 2257 hr->reset_gc_time_stamp(); 2258 if (hr->startsHumongous()) { 2259 uint first_index = hr->hrs_index() + 1; 2260 uint last_index = hr->last_hc_index(); 2261 for (uint i = first_index; i < last_index; i += 1) { 2262 HeapRegion* chr = region_at(i); 2263 assert(chr->continuesHumongous(), "sanity"); 2264 chr->reset_gc_time_stamp(); 2265 } 2266 } 2267 } 2268 2269 #ifndef PRODUCT 2270 class CheckGCTimeStampsHRClosure : public HeapRegionClosure { 2271 private: 2272 unsigned _gc_time_stamp; 2273 bool _failures; 2274 2275 public: 2276 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) : 2277 _gc_time_stamp(gc_time_stamp), _failures(false) { } 2278 2279 virtual bool doHeapRegion(HeapRegion* hr) { 2280 unsigned region_gc_time_stamp = hr->get_gc_time_stamp(); 2281 if (_gc_time_stamp != region_gc_time_stamp) { 2282 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, " 2283 "expected %d", HR_FORMAT_PARAMS(hr), 2284 region_gc_time_stamp, _gc_time_stamp); 2285 _failures = true; 2286 } 2287 return false; 2288 } 2289 2290 bool failures() { return _failures; } 2291 }; 2292 2293 void G1CollectedHeap::check_gc_time_stamps() { 2294 CheckGCTimeStampsHRClosure cl(_gc_time_stamp); 2295 heap_region_iterate(&cl); 2296 guarantee(!cl.failures(), "all GC time stamps should have been reset"); 2297 } 2298 #endif // PRODUCT 2299 2300 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, 2301 DirtyCardQueue* into_cset_dcq, 2302 bool concurrent, 2303 uint worker_i) { 2304 // Clean cards in the hot card cache 2305 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 2306 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq); 2307 2308 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 2309 int n_completed_buffers = 0; 2310 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) { 2311 n_completed_buffers++; 2312 } 2313 g1_policy()->phase_times()->record_update_rs_processed_buffers(worker_i, n_completed_buffers); 2314 dcqs.clear_n_completed_buffers(); 2315 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!"); 2316 } 2317 2318 2319 // Computes the sum of the storage used by the various regions. 2320 2321 size_t G1CollectedHeap::used() const { 2322 assert(Heap_lock->owner() != NULL, 2323 "Should be owned on this thread's behalf."); 2324 size_t result = _summary_bytes_used; 2325 // Read only once in case it is set to NULL concurrently 2326 HeapRegion* hr = _mutator_alloc_region.get(); 2327 if (hr != NULL) 2328 result += hr->used(); 2329 return result; 2330 } 2331 2332 size_t G1CollectedHeap::used_unlocked() const { 2333 size_t result = _summary_bytes_used; 2334 return result; 2335 } 2336 2337 class SumUsedClosure: public HeapRegionClosure { 2338 size_t _used; 2339 public: 2340 SumUsedClosure() : _used(0) {} 2341 bool doHeapRegion(HeapRegion* r) { 2342 if (!r->continuesHumongous()) { 2343 _used += r->used(); 2344 } 2345 return false; 2346 } 2347 size_t result() { return _used; } 2348 }; 2349 2350 size_t G1CollectedHeap::recalculate_used() const { 2351 double recalculate_used_start = os::elapsedTime(); 2352 2353 SumUsedClosure blk; 2354 heap_region_iterate(&blk); 2355 2356 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0); 2357 return blk.result(); 2358 } 2359 2360 size_t G1CollectedHeap::unsafe_max_alloc() { 2361 if (free_regions() > 0) return HeapRegion::GrainBytes; 2362 // otherwise, is there space in the current allocation region? 2363 2364 // We need to store the current allocation region in a local variable 2365 // here. The problem is that this method doesn't take any locks and 2366 // there may be other threads which overwrite the current allocation 2367 // region field. attempt_allocation(), for example, sets it to NULL 2368 // and this can happen *after* the NULL check here but before the call 2369 // to free(), resulting in a SIGSEGV. Note that this doesn't appear 2370 // to be a problem in the optimized build, since the two loads of the 2371 // current allocation region field are optimized away. 2372 HeapRegion* hr = _mutator_alloc_region.get(); 2373 if (hr == NULL) { 2374 return 0; 2375 } 2376 return hr->free(); 2377 } 2378 2379 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 2380 switch (cause) { 2381 case GCCause::_gc_locker: return GCLockerInvokesConcurrent; 2382 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent; 2383 case GCCause::_g1_humongous_allocation: return true; 2384 default: return false; 2385 } 2386 } 2387 2388 #ifndef PRODUCT 2389 void G1CollectedHeap::allocate_dummy_regions() { 2390 // Let's fill up most of the region 2391 size_t word_size = HeapRegion::GrainWords - 1024; 2392 // And as a result the region we'll allocate will be humongous. 2393 guarantee(isHumongous(word_size), "sanity"); 2394 2395 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) { 2396 // Let's use the existing mechanism for the allocation 2397 HeapWord* dummy_obj = humongous_obj_allocate(word_size); 2398 if (dummy_obj != NULL) { 2399 MemRegion mr(dummy_obj, word_size); 2400 CollectedHeap::fill_with_object(mr); 2401 } else { 2402 // If we can't allocate once, we probably cannot allocate 2403 // again. Let's get out of the loop. 2404 break; 2405 } 2406 } 2407 } 2408 #endif // !PRODUCT 2409 2410 void G1CollectedHeap::increment_old_marking_cycles_started() { 2411 assert(_old_marking_cycles_started == _old_marking_cycles_completed || 2412 _old_marking_cycles_started == _old_marking_cycles_completed + 1, 2413 err_msg("Wrong marking cycle count (started: %d, completed: %d)", 2414 _old_marking_cycles_started, _old_marking_cycles_completed)); 2415 2416 _old_marking_cycles_started++; 2417 } 2418 2419 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) { 2420 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 2421 2422 // We assume that if concurrent == true, then the caller is a 2423 // concurrent thread that was joined the Suspendible Thread 2424 // Set. If there's ever a cheap way to check this, we should add an 2425 // assert here. 2426 2427 // Given that this method is called at the end of a Full GC or of a 2428 // concurrent cycle, and those can be nested (i.e., a Full GC can 2429 // interrupt a concurrent cycle), the number of full collections 2430 // completed should be either one (in the case where there was no 2431 // nesting) or two (when a Full GC interrupted a concurrent cycle) 2432 // behind the number of full collections started. 2433 2434 // This is the case for the inner caller, i.e. a Full GC. 2435 assert(concurrent || 2436 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || 2437 (_old_marking_cycles_started == _old_marking_cycles_completed + 2), 2438 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u " 2439 "is inconsistent with _old_marking_cycles_completed = %u", 2440 _old_marking_cycles_started, _old_marking_cycles_completed)); 2441 2442 // This is the case for the outer caller, i.e. the concurrent cycle. 2443 assert(!concurrent || 2444 (_old_marking_cycles_started == _old_marking_cycles_completed + 1), 2445 err_msg("for outer caller (concurrent cycle): " 2446 "_old_marking_cycles_started = %u " 2447 "is inconsistent with _old_marking_cycles_completed = %u", 2448 _old_marking_cycles_started, _old_marking_cycles_completed)); 2449 2450 _old_marking_cycles_completed += 1; 2451 2452 // We need to clear the "in_progress" flag in the CM thread before 2453 // we wake up any waiters (especially when ExplicitInvokesConcurrent 2454 // is set) so that if a waiter requests another System.gc() it doesn't 2455 // incorrectly see that a marking cycle is still in progress. 2456 if (concurrent) { 2457 _cmThread->clear_in_progress(); 2458 } 2459 2460 // This notify_all() will ensure that a thread that called 2461 // System.gc() with (with ExplicitGCInvokesConcurrent set or not) 2462 // and it's waiting for a full GC to finish will be woken up. It is 2463 // waiting in VM_G1IncCollectionPause::doit_epilogue(). 2464 FullGCCount_lock->notify_all(); 2465 } 2466 2467 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) { 2468 _concurrent_cycle_started = true; 2469 _gc_timer_cm->register_gc_start(start_time); 2470 2471 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start()); 2472 trace_heap_before_gc(_gc_tracer_cm); 2473 } 2474 2475 void G1CollectedHeap::register_concurrent_cycle_end() { 2476 if (_concurrent_cycle_started) { 2477 if (_cm->has_aborted()) { 2478 _gc_tracer_cm->report_concurrent_mode_failure(); 2479 } 2480 2481 _gc_timer_cm->register_gc_end(); 2482 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions()); 2483 2484 _concurrent_cycle_started = false; 2485 } 2486 } 2487 2488 void G1CollectedHeap::trace_heap_after_concurrent_cycle() { 2489 if (_concurrent_cycle_started) { 2490 trace_heap_after_gc(_gc_tracer_cm); 2491 } 2492 } 2493 2494 G1YCType G1CollectedHeap::yc_type() { 2495 bool is_young = g1_policy()->gcs_are_young(); 2496 bool is_initial_mark = g1_policy()->during_initial_mark_pause(); 2497 bool is_during_mark = mark_in_progress(); 2498 2499 if (is_initial_mark) { 2500 return InitialMark; 2501 } else if (is_during_mark) { 2502 return DuringMark; 2503 } else if (is_young) { 2504 return Normal; 2505 } else { 2506 return Mixed; 2507 } 2508 } 2509 2510 void G1CollectedHeap::collect(GCCause::Cause cause) { 2511 assert_heap_not_locked(); 2512 2513 unsigned int gc_count_before; 2514 unsigned int old_marking_count_before; 2515 bool retry_gc; 2516 2517 do { 2518 retry_gc = false; 2519 2520 { 2521 MutexLocker ml(Heap_lock); 2522 2523 // Read the GC count while holding the Heap_lock 2524 gc_count_before = total_collections(); 2525 old_marking_count_before = _old_marking_cycles_started; 2526 } 2527 2528 if (should_do_concurrent_full_gc(cause)) { 2529 // Schedule an initial-mark evacuation pause that will start a 2530 // concurrent cycle. We're setting word_size to 0 which means that 2531 // we are not requesting a post-GC allocation. 2532 VM_G1IncCollectionPause op(gc_count_before, 2533 0, /* word_size */ 2534 true, /* should_initiate_conc_mark */ 2535 g1_policy()->max_pause_time_ms(), 2536 cause); 2537 2538 VMThread::execute(&op); 2539 if (!op.pause_succeeded()) { 2540 if (old_marking_count_before == _old_marking_cycles_started) { 2541 retry_gc = op.should_retry_gc(); 2542 } else { 2543 // A Full GC happened while we were trying to schedule the 2544 // initial-mark GC. No point in starting a new cycle given 2545 // that the whole heap was collected anyway. 2546 } 2547 2548 if (retry_gc) { 2549 if (GC_locker::is_active_and_needs_gc()) { 2550 GC_locker::stall_until_clear(); 2551 } 2552 } 2553 } 2554 } else { 2555 if (cause == GCCause::_gc_locker 2556 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { 2557 2558 // Schedule a standard evacuation pause. We're setting word_size 2559 // to 0 which means that we are not requesting a post-GC allocation. 2560 VM_G1IncCollectionPause op(gc_count_before, 2561 0, /* word_size */ 2562 false, /* should_initiate_conc_mark */ 2563 g1_policy()->max_pause_time_ms(), 2564 cause); 2565 VMThread::execute(&op); 2566 } else { 2567 // Schedule a Full GC. 2568 VM_G1CollectFull op(gc_count_before, old_marking_count_before, cause); 2569 VMThread::execute(&op); 2570 } 2571 } 2572 } while (retry_gc); 2573 } 2574 2575 bool G1CollectedHeap::is_in(const void* p) const { 2576 if (_g1_committed.contains(p)) { 2577 // Given that we know that p is in the committed space, 2578 // heap_region_containing_raw() should successfully 2579 // return the containing region. 2580 HeapRegion* hr = heap_region_containing_raw(p); 2581 return hr->is_in(p); 2582 } else { 2583 return false; 2584 } 2585 } 2586 2587 // Iteration functions. 2588 2589 // Iterates an OopClosure over all ref-containing fields of objects 2590 // within a HeapRegion. 2591 2592 class IterateOopClosureRegionClosure: public HeapRegionClosure { 2593 MemRegion _mr; 2594 ExtendedOopClosure* _cl; 2595 public: 2596 IterateOopClosureRegionClosure(MemRegion mr, ExtendedOopClosure* cl) 2597 : _mr(mr), _cl(cl) {} 2598 bool doHeapRegion(HeapRegion* r) { 2599 if (!r->continuesHumongous()) { 2600 r->oop_iterate(_cl); 2601 } 2602 return false; 2603 } 2604 }; 2605 2606 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) { 2607 IterateOopClosureRegionClosure blk(_g1_committed, cl); 2608 heap_region_iterate(&blk); 2609 } 2610 2611 void G1CollectedHeap::oop_iterate(MemRegion mr, ExtendedOopClosure* cl) { 2612 IterateOopClosureRegionClosure blk(mr, cl); 2613 heap_region_iterate(&blk); 2614 } 2615 2616 // Iterates an ObjectClosure over all objects within a HeapRegion. 2617 2618 class IterateObjectClosureRegionClosure: public HeapRegionClosure { 2619 ObjectClosure* _cl; 2620 public: 2621 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} 2622 bool doHeapRegion(HeapRegion* r) { 2623 if (! r->continuesHumongous()) { 2624 r->object_iterate(_cl); 2625 } 2626 return false; 2627 } 2628 }; 2629 2630 void G1CollectedHeap::object_iterate(ObjectClosure* cl) { 2631 IterateObjectClosureRegionClosure blk(cl); 2632 heap_region_iterate(&blk); 2633 } 2634 2635 // Calls a SpaceClosure on a HeapRegion. 2636 2637 class SpaceClosureRegionClosure: public HeapRegionClosure { 2638 SpaceClosure* _cl; 2639 public: 2640 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {} 2641 bool doHeapRegion(HeapRegion* r) { 2642 _cl->do_space(r); 2643 return false; 2644 } 2645 }; 2646 2647 void G1CollectedHeap::space_iterate(SpaceClosure* cl) { 2648 SpaceClosureRegionClosure blk(cl); 2649 heap_region_iterate(&blk); 2650 } 2651 2652 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { 2653 _hrs.iterate(cl); 2654 } 2655 2656 void 2657 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl, 2658 uint worker_id, 2659 uint no_of_par_workers, 2660 jint claim_value) { 2661 const uint regions = n_regions(); 2662 const uint max_workers = (G1CollectedHeap::use_parallel_gc_threads() ? 2663 no_of_par_workers : 2664 1); 2665 assert(UseDynamicNumberOfGCThreads || 2666 no_of_par_workers == workers()->total_workers(), 2667 "Non dynamic should use fixed number of workers"); 2668 // try to spread out the starting points of the workers 2669 const HeapRegion* start_hr = 2670 start_region_for_worker(worker_id, no_of_par_workers); 2671 const uint start_index = start_hr->hrs_index(); 2672 2673 // each worker will actually look at all regions 2674 for (uint count = 0; count < regions; ++count) { 2675 const uint index = (start_index + count) % regions; 2676 assert(0 <= index && index < regions, "sanity"); 2677 HeapRegion* r = region_at(index); 2678 // we'll ignore "continues humongous" regions (we'll process them 2679 // when we come across their corresponding "start humongous" 2680 // region) and regions already claimed 2681 if (r->claim_value() == claim_value || r->continuesHumongous()) { 2682 continue; 2683 } 2684 // OK, try to claim it 2685 if (r->claimHeapRegion(claim_value)) { 2686 // success! 2687 assert(!r->continuesHumongous(), "sanity"); 2688 if (r->startsHumongous()) { 2689 // If the region is "starts humongous" we'll iterate over its 2690 // "continues humongous" first; in fact we'll do them 2691 // first. The order is important. In on case, calling the 2692 // closure on the "starts humongous" region might de-allocate 2693 // and clear all its "continues humongous" regions and, as a 2694 // result, we might end up processing them twice. So, we'll do 2695 // them first (notice: most closures will ignore them anyway) and 2696 // then we'll do the "starts humongous" region. 2697 for (uint ch_index = index + 1; ch_index < regions; ++ch_index) { 2698 HeapRegion* chr = region_at(ch_index); 2699 2700 // if the region has already been claimed or it's not 2701 // "continues humongous" we're done 2702 if (chr->claim_value() == claim_value || 2703 !chr->continuesHumongous()) { 2704 break; 2705 } 2706 2707 // No one should have claimed it directly. We can given 2708 // that we claimed its "starts humongous" region. 2709 assert(chr->claim_value() != claim_value, "sanity"); 2710 assert(chr->humongous_start_region() == r, "sanity"); 2711 2712 if (chr->claimHeapRegion(claim_value)) { 2713 // we should always be able to claim it; no one else should 2714 // be trying to claim this region 2715 2716 bool res2 = cl->doHeapRegion(chr); 2717 assert(!res2, "Should not abort"); 2718 2719 // Right now, this holds (i.e., no closure that actually 2720 // does something with "continues humongous" regions 2721 // clears them). We might have to weaken it in the future, 2722 // but let's leave these two asserts here for extra safety. 2723 assert(chr->continuesHumongous(), "should still be the case"); 2724 assert(chr->humongous_start_region() == r, "sanity"); 2725 } else { 2726 guarantee(false, "we should not reach here"); 2727 } 2728 } 2729 } 2730 2731 assert(!r->continuesHumongous(), "sanity"); 2732 bool res = cl->doHeapRegion(r); 2733 assert(!res, "Should not abort"); 2734 } 2735 } 2736 } 2737 2738 class ResetClaimValuesClosure: public HeapRegionClosure { 2739 public: 2740 bool doHeapRegion(HeapRegion* r) { 2741 r->set_claim_value(HeapRegion::InitialClaimValue); 2742 return false; 2743 } 2744 }; 2745 2746 void G1CollectedHeap::reset_heap_region_claim_values() { 2747 ResetClaimValuesClosure blk; 2748 heap_region_iterate(&blk); 2749 } 2750 2751 void G1CollectedHeap::reset_cset_heap_region_claim_values() { 2752 ResetClaimValuesClosure blk; 2753 collection_set_iterate(&blk); 2754 } 2755 2756 #ifdef ASSERT 2757 // This checks whether all regions in the heap have the correct claim 2758 // value. I also piggy-backed on this a check to ensure that the 2759 // humongous_start_region() information on "continues humongous" 2760 // regions is correct. 2761 2762 class CheckClaimValuesClosure : public HeapRegionClosure { 2763 private: 2764 jint _claim_value; 2765 uint _failures; 2766 HeapRegion* _sh_region; 2767 2768 public: 2769 CheckClaimValuesClosure(jint claim_value) : 2770 _claim_value(claim_value), _failures(0), _sh_region(NULL) { } 2771 bool doHeapRegion(HeapRegion* r) { 2772 if (r->claim_value() != _claim_value) { 2773 gclog_or_tty->print_cr("Region " HR_FORMAT ", " 2774 "claim value = %d, should be %d", 2775 HR_FORMAT_PARAMS(r), 2776 r->claim_value(), _claim_value); 2777 ++_failures; 2778 } 2779 if (!r->isHumongous()) { 2780 _sh_region = NULL; 2781 } else if (r->startsHumongous()) { 2782 _sh_region = r; 2783 } else if (r->continuesHumongous()) { 2784 if (r->humongous_start_region() != _sh_region) { 2785 gclog_or_tty->print_cr("Region " HR_FORMAT ", " 2786 "HS = "PTR_FORMAT", should be "PTR_FORMAT, 2787 HR_FORMAT_PARAMS(r), 2788 r->humongous_start_region(), 2789 _sh_region); 2790 ++_failures; 2791 } 2792 } 2793 return false; 2794 } 2795 uint failures() { return _failures; } 2796 }; 2797 2798 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) { 2799 CheckClaimValuesClosure cl(claim_value); 2800 heap_region_iterate(&cl); 2801 return cl.failures() == 0; 2802 } 2803 2804 class CheckClaimValuesInCSetHRClosure: public HeapRegionClosure { 2805 private: 2806 jint _claim_value; 2807 uint _failures; 2808 2809 public: 2810 CheckClaimValuesInCSetHRClosure(jint claim_value) : 2811 _claim_value(claim_value), _failures(0) { } 2812 2813 uint failures() { return _failures; } 2814 2815 bool doHeapRegion(HeapRegion* hr) { 2816 assert(hr->in_collection_set(), "how?"); 2817 assert(!hr->isHumongous(), "H-region in CSet"); 2818 if (hr->claim_value() != _claim_value) { 2819 gclog_or_tty->print_cr("CSet Region " HR_FORMAT ", " 2820 "claim value = %d, should be %d", 2821 HR_FORMAT_PARAMS(hr), 2822 hr->claim_value(), _claim_value); 2823 _failures += 1; 2824 } 2825 return false; 2826 } 2827 }; 2828 2829 bool G1CollectedHeap::check_cset_heap_region_claim_values(jint claim_value) { 2830 CheckClaimValuesInCSetHRClosure cl(claim_value); 2831 collection_set_iterate(&cl); 2832 return cl.failures() == 0; 2833 } 2834 #endif // ASSERT 2835 2836 // Clear the cached CSet starting regions and (more importantly) 2837 // the time stamps. Called when we reset the GC time stamp. 2838 void G1CollectedHeap::clear_cset_start_regions() { 2839 assert(_worker_cset_start_region != NULL, "sanity"); 2840 assert(_worker_cset_start_region_time_stamp != NULL, "sanity"); 2841 2842 int n_queues = MAX2((int)ParallelGCThreads, 1); 2843 for (int i = 0; i < n_queues; i++) { 2844 _worker_cset_start_region[i] = NULL; 2845 _worker_cset_start_region_time_stamp[i] = 0; 2846 } 2847 } 2848 2849 // Given the id of a worker, obtain or calculate a suitable 2850 // starting region for iterating over the current collection set. 2851 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) { 2852 assert(get_gc_time_stamp() > 0, "should have been updated by now"); 2853 2854 HeapRegion* result = NULL; 2855 unsigned gc_time_stamp = get_gc_time_stamp(); 2856 2857 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) { 2858 // Cached starting region for current worker was set 2859 // during the current pause - so it's valid. 2860 // Note: the cached starting heap region may be NULL 2861 // (when the collection set is empty). 2862 result = _worker_cset_start_region[worker_i]; 2863 assert(result == NULL || result->in_collection_set(), "sanity"); 2864 return result; 2865 } 2866 2867 // The cached entry was not valid so let's calculate 2868 // a suitable starting heap region for this worker. 2869 2870 // We want the parallel threads to start their collection 2871 // set iteration at different collection set regions to 2872 // avoid contention. 2873 // If we have: 2874 // n collection set regions 2875 // p threads 2876 // Then thread t will start at region floor ((t * n) / p) 2877 2878 result = g1_policy()->collection_set(); 2879 if (G1CollectedHeap::use_parallel_gc_threads()) { 2880 uint cs_size = g1_policy()->cset_region_length(); 2881 uint active_workers = workers()->active_workers(); 2882 assert(UseDynamicNumberOfGCThreads || 2883 active_workers == workers()->total_workers(), 2884 "Unless dynamic should use total workers"); 2885 2886 uint end_ind = (cs_size * worker_i) / active_workers; 2887 uint start_ind = 0; 2888 2889 if (worker_i > 0 && 2890 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) { 2891 // Previous workers starting region is valid 2892 // so let's iterate from there 2893 start_ind = (cs_size * (worker_i - 1)) / active_workers; 2894 result = _worker_cset_start_region[worker_i - 1]; 2895 } 2896 2897 for (uint i = start_ind; i < end_ind; i++) { 2898 result = result->next_in_collection_set(); 2899 } 2900 } 2901 2902 // Note: the calculated starting heap region may be NULL 2903 // (when the collection set is empty). 2904 assert(result == NULL || result->in_collection_set(), "sanity"); 2905 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp, 2906 "should be updated only once per pause"); 2907 _worker_cset_start_region[worker_i] = result; 2908 OrderAccess::storestore(); 2909 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp; 2910 return result; 2911 } 2912 2913 HeapRegion* G1CollectedHeap::start_region_for_worker(uint worker_i, 2914 uint no_of_par_workers) { 2915 uint worker_num = 2916 G1CollectedHeap::use_parallel_gc_threads() ? no_of_par_workers : 1U; 2917 assert(UseDynamicNumberOfGCThreads || 2918 no_of_par_workers == workers()->total_workers(), 2919 "Non dynamic should use fixed number of workers"); 2920 const uint start_index = n_regions() * worker_i / worker_num; 2921 return region_at(start_index); 2922 } 2923 2924 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) { 2925 HeapRegion* r = g1_policy()->collection_set(); 2926 while (r != NULL) { 2927 HeapRegion* next = r->next_in_collection_set(); 2928 if (cl->doHeapRegion(r)) { 2929 cl->incomplete(); 2930 return; 2931 } 2932 r = next; 2933 } 2934 } 2935 2936 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r, 2937 HeapRegionClosure *cl) { 2938 if (r == NULL) { 2939 // The CSet is empty so there's nothing to do. 2940 return; 2941 } 2942 2943 assert(r->in_collection_set(), 2944 "Start region must be a member of the collection set."); 2945 HeapRegion* cur = r; 2946 while (cur != NULL) { 2947 HeapRegion* next = cur->next_in_collection_set(); 2948 if (cl->doHeapRegion(cur) && false) { 2949 cl->incomplete(); 2950 return; 2951 } 2952 cur = next; 2953 } 2954 cur = g1_policy()->collection_set(); 2955 while (cur != r) { 2956 HeapRegion* next = cur->next_in_collection_set(); 2957 if (cl->doHeapRegion(cur) && false) { 2958 cl->incomplete(); 2959 return; 2960 } 2961 cur = next; 2962 } 2963 } 2964 2965 CompactibleSpace* G1CollectedHeap::first_compactible_space() { 2966 return n_regions() > 0 ? region_at(0) : NULL; 2967 } 2968 2969 2970 Space* G1CollectedHeap::space_containing(const void* addr) const { 2971 Space* res = heap_region_containing(addr); 2972 return res; 2973 } 2974 2975 HeapWord* G1CollectedHeap::block_start(const void* addr) const { 2976 Space* sp = space_containing(addr); 2977 if (sp != NULL) { 2978 return sp->block_start(addr); 2979 } 2980 return NULL; 2981 } 2982 2983 size_t G1CollectedHeap::block_size(const HeapWord* addr) const { 2984 Space* sp = space_containing(addr); 2985 assert(sp != NULL, "block_size of address outside of heap"); 2986 return sp->block_size(addr); 2987 } 2988 2989 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { 2990 Space* sp = space_containing(addr); 2991 return sp->block_is_obj(addr); 2992 } 2993 2994 bool G1CollectedHeap::supports_tlab_allocation() const { 2995 return true; 2996 } 2997 2998 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { 2999 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes; 3000 } 3001 3002 size_t G1CollectedHeap::tlab_used(Thread* ignored) const { 3003 return young_list()->eden_used_bytes(); 3004 } 3005 3006 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size 3007 // must be smaller than the humongous object limit. 3008 size_t G1CollectedHeap::max_tlab_size() const { 3009 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment); 3010 } 3011 3012 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { 3013 // Return the remaining space in the cur alloc region, but not less than 3014 // the min TLAB size. 3015 3016 // Also, this value can be at most the humongous object threshold, 3017 // since we can't allow tlabs to grow big enough to accommodate 3018 // humongous objects. 3019 3020 HeapRegion* hr = _mutator_alloc_region.get(); 3021 size_t max_tlab = max_tlab_size() * wordSize; 3022 if (hr == NULL) { 3023 return max_tlab; 3024 } else { 3025 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab); 3026 } 3027 } 3028 3029 size_t G1CollectedHeap::max_capacity() const { 3030 return _g1_reserved.byte_size(); 3031 } 3032 3033 jlong G1CollectedHeap::millis_since_last_gc() { 3034 // assert(false, "NYI"); 3035 return 0; 3036 } 3037 3038 void G1CollectedHeap::prepare_for_verify() { 3039 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) { 3040 ensure_parsability(false); 3041 } 3042 g1_rem_set()->prepare_for_verify(); 3043 } 3044 3045 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr, 3046 VerifyOption vo) { 3047 switch (vo) { 3048 case VerifyOption_G1UsePrevMarking: 3049 return hr->obj_allocated_since_prev_marking(obj); 3050 case VerifyOption_G1UseNextMarking: 3051 return hr->obj_allocated_since_next_marking(obj); 3052 case VerifyOption_G1UseMarkWord: 3053 return false; 3054 default: 3055 ShouldNotReachHere(); 3056 } 3057 return false; // keep some compilers happy 3058 } 3059 3060 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) { 3061 switch (vo) { 3062 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start(); 3063 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start(); 3064 case VerifyOption_G1UseMarkWord: return NULL; 3065 default: ShouldNotReachHere(); 3066 } 3067 return NULL; // keep some compilers happy 3068 } 3069 3070 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) { 3071 switch (vo) { 3072 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj); 3073 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj); 3074 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked(); 3075 default: ShouldNotReachHere(); 3076 } 3077 return false; // keep some compilers happy 3078 } 3079 3080 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) { 3081 switch (vo) { 3082 case VerifyOption_G1UsePrevMarking: return "PTAMS"; 3083 case VerifyOption_G1UseNextMarking: return "NTAMS"; 3084 case VerifyOption_G1UseMarkWord: return "NONE"; 3085 default: ShouldNotReachHere(); 3086 } 3087 return NULL; // keep some compilers happy 3088 } 3089 3090 class VerifyRootsClosure: public OopClosure { 3091 private: 3092 G1CollectedHeap* _g1h; 3093 VerifyOption _vo; 3094 bool _failures; 3095 public: 3096 // _vo == UsePrevMarking -> use "prev" marking information, 3097 // _vo == UseNextMarking -> use "next" marking information, 3098 // _vo == UseMarkWord -> use mark word from object header. 3099 VerifyRootsClosure(VerifyOption vo) : 3100 _g1h(G1CollectedHeap::heap()), 3101 _vo(vo), 3102 _failures(false) { } 3103 3104 bool failures() { return _failures; } 3105 3106 template <class T> void do_oop_nv(T* p) { 3107 T heap_oop = oopDesc::load_heap_oop(p); 3108 if (!oopDesc::is_null(heap_oop)) { 3109 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 3110 if (_g1h->is_obj_dead_cond(obj, _vo)) { 3111 gclog_or_tty->print_cr("Root location "PTR_FORMAT" " 3112 "points to dead obj "PTR_FORMAT, p, (void*) obj); 3113 if (_vo == VerifyOption_G1UseMarkWord) { 3114 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark())); 3115 } 3116 obj->print_on(gclog_or_tty); 3117 _failures = true; 3118 } 3119 } 3120 } 3121 3122 void do_oop(oop* p) { do_oop_nv(p); } 3123 void do_oop(narrowOop* p) { do_oop_nv(p); } 3124 }; 3125 3126 class G1VerifyCodeRootOopClosure: public OopClosure { 3127 G1CollectedHeap* _g1h; 3128 OopClosure* _root_cl; 3129 nmethod* _nm; 3130 VerifyOption _vo; 3131 bool _failures; 3132 3133 template <class T> void do_oop_work(T* p) { 3134 // First verify that this root is live 3135 _root_cl->do_oop(p); 3136 3137 if (!G1VerifyHeapRegionCodeRoots) { 3138 // We're not verifying the code roots attached to heap region. 3139 return; 3140 } 3141 3142 // Don't check the code roots during marking verification in a full GC 3143 if (_vo == VerifyOption_G1UseMarkWord) { 3144 return; 3145 } 3146 3147 // Now verify that the current nmethod (which contains p) is 3148 // in the code root list of the heap region containing the 3149 // object referenced by p. 3150 3151 T heap_oop = oopDesc::load_heap_oop(p); 3152 if (!oopDesc::is_null(heap_oop)) { 3153 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 3154 3155 // Now fetch the region containing the object 3156 HeapRegion* hr = _g1h->heap_region_containing(obj); 3157 HeapRegionRemSet* hrrs = hr->rem_set(); 3158 // Verify that the strong code root list for this region 3159 // contains the nmethod 3160 if (!hrrs->strong_code_roots_list_contains(_nm)) { 3161 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" " 3162 "from nmethod "PTR_FORMAT" not in strong " 3163 "code roots for region ["PTR_FORMAT","PTR_FORMAT")", 3164 p, _nm, hr->bottom(), hr->end()); 3165 _failures = true; 3166 } 3167 } 3168 } 3169 3170 public: 3171 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo): 3172 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {} 3173 3174 void do_oop(oop* p) { do_oop_work(p); } 3175 void do_oop(narrowOop* p) { do_oop_work(p); } 3176 3177 void set_nmethod(nmethod* nm) { _nm = nm; } 3178 bool failures() { return _failures; } 3179 }; 3180 3181 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure { 3182 G1VerifyCodeRootOopClosure* _oop_cl; 3183 3184 public: 3185 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl): 3186 _oop_cl(oop_cl) {} 3187 3188 void do_code_blob(CodeBlob* cb) { 3189 nmethod* nm = cb->as_nmethod_or_null(); 3190 if (nm != NULL) { 3191 _oop_cl->set_nmethod(nm); 3192 nm->oops_do(_oop_cl); 3193 } 3194 } 3195 }; 3196 3197 class YoungRefCounterClosure : public OopClosure { 3198 G1CollectedHeap* _g1h; 3199 int _count; 3200 public: 3201 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {} 3202 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } } 3203 void do_oop(narrowOop* p) { ShouldNotReachHere(); } 3204 3205 int count() { return _count; } 3206 void reset_count() { _count = 0; }; 3207 }; 3208 3209 class VerifyKlassClosure: public KlassClosure { 3210 YoungRefCounterClosure _young_ref_counter_closure; 3211 OopClosure *_oop_closure; 3212 public: 3213 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {} 3214 void do_klass(Klass* k) { 3215 k->oops_do(_oop_closure); 3216 3217 _young_ref_counter_closure.reset_count(); 3218 k->oops_do(&_young_ref_counter_closure); 3219 if (_young_ref_counter_closure.count() > 0) { 3220 guarantee(k->has_modified_oops(), err_msg("Klass %p, has young refs but is not dirty.", k)); 3221 } 3222 } 3223 }; 3224 3225 class VerifyLivenessOopClosure: public OopClosure { 3226 G1CollectedHeap* _g1h; 3227 VerifyOption _vo; 3228 public: 3229 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo): 3230 _g1h(g1h), _vo(vo) 3231 { } 3232 void do_oop(narrowOop *p) { do_oop_work(p); } 3233 void do_oop( oop *p) { do_oop_work(p); } 3234 3235 template <class T> void do_oop_work(T *p) { 3236 oop obj = oopDesc::load_decode_heap_oop(p); 3237 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo), 3238 "Dead object referenced by a not dead object"); 3239 } 3240 }; 3241 3242 class VerifyObjsInRegionClosure: public ObjectClosure { 3243 private: 3244 G1CollectedHeap* _g1h; 3245 size_t _live_bytes; 3246 HeapRegion *_hr; 3247 VerifyOption _vo; 3248 public: 3249 // _vo == UsePrevMarking -> use "prev" marking information, 3250 // _vo == UseNextMarking -> use "next" marking information, 3251 // _vo == UseMarkWord -> use mark word from object header. 3252 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo) 3253 : _live_bytes(0), _hr(hr), _vo(vo) { 3254 _g1h = G1CollectedHeap::heap(); 3255 } 3256 void do_object(oop o) { 3257 VerifyLivenessOopClosure isLive(_g1h, _vo); 3258 assert(o != NULL, "Huh?"); 3259 if (!_g1h->is_obj_dead_cond(o, _vo)) { 3260 // If the object is alive according to the mark word, 3261 // then verify that the marking information agrees. 3262 // Note we can't verify the contra-positive of the 3263 // above: if the object is dead (according to the mark 3264 // word), it may not be marked, or may have been marked 3265 // but has since became dead, or may have been allocated 3266 // since the last marking. 3267 if (_vo == VerifyOption_G1UseMarkWord) { 3268 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch"); 3269 } 3270 3271 o->oop_iterate_no_header(&isLive); 3272 if (!_hr->obj_allocated_since_prev_marking(o)) { 3273 size_t obj_size = o->size(); // Make sure we don't overflow 3274 _live_bytes += (obj_size * HeapWordSize); 3275 } 3276 } 3277 } 3278 size_t live_bytes() { return _live_bytes; } 3279 }; 3280 3281 class PrintObjsInRegionClosure : public ObjectClosure { 3282 HeapRegion *_hr; 3283 G1CollectedHeap *_g1; 3284 public: 3285 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) { 3286 _g1 = G1CollectedHeap::heap(); 3287 }; 3288 3289 void do_object(oop o) { 3290 if (o != NULL) { 3291 HeapWord *start = (HeapWord *) o; 3292 size_t word_sz = o->size(); 3293 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT 3294 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n", 3295 (void*) o, word_sz, 3296 _g1->isMarkedPrev(o), 3297 _g1->isMarkedNext(o), 3298 _hr->obj_allocated_since_prev_marking(o)); 3299 HeapWord *end = start + word_sz; 3300 HeapWord *cur; 3301 int *val; 3302 for (cur = start; cur < end; cur++) { 3303 val = (int *) cur; 3304 gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val); 3305 } 3306 } 3307 } 3308 }; 3309 3310 class VerifyRegionClosure: public HeapRegionClosure { 3311 private: 3312 bool _par; 3313 VerifyOption _vo; 3314 bool _failures; 3315 public: 3316 // _vo == UsePrevMarking -> use "prev" marking information, 3317 // _vo == UseNextMarking -> use "next" marking information, 3318 // _vo == UseMarkWord -> use mark word from object header. 3319 VerifyRegionClosure(bool par, VerifyOption vo) 3320 : _par(par), 3321 _vo(vo), 3322 _failures(false) {} 3323 3324 bool failures() { 3325 return _failures; 3326 } 3327 3328 bool doHeapRegion(HeapRegion* r) { 3329 if (!r->continuesHumongous()) { 3330 bool failures = false; 3331 r->verify(_vo, &failures); 3332 if (failures) { 3333 _failures = true; 3334 } else { 3335 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo); 3336 r->object_iterate(¬_dead_yet_cl); 3337 if (_vo != VerifyOption_G1UseNextMarking) { 3338 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) { 3339 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] " 3340 "max_live_bytes "SIZE_FORMAT" " 3341 "< calculated "SIZE_FORMAT, 3342 r->bottom(), r->end(), 3343 r->max_live_bytes(), 3344 not_dead_yet_cl.live_bytes()); 3345 _failures = true; 3346 } 3347 } else { 3348 // When vo == UseNextMarking we cannot currently do a sanity 3349 // check on the live bytes as the calculation has not been 3350 // finalized yet. 3351 } 3352 } 3353 } 3354 return false; // stop the region iteration if we hit a failure 3355 } 3356 }; 3357 3358 // This is the task used for parallel verification of the heap regions 3359 3360 class G1ParVerifyTask: public AbstractGangTask { 3361 private: 3362 G1CollectedHeap* _g1h; 3363 VerifyOption _vo; 3364 bool _failures; 3365 3366 public: 3367 // _vo == UsePrevMarking -> use "prev" marking information, 3368 // _vo == UseNextMarking -> use "next" marking information, 3369 // _vo == UseMarkWord -> use mark word from object header. 3370 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) : 3371 AbstractGangTask("Parallel verify task"), 3372 _g1h(g1h), 3373 _vo(vo), 3374 _failures(false) { } 3375 3376 bool failures() { 3377 return _failures; 3378 } 3379 3380 void work(uint worker_id) { 3381 HandleMark hm; 3382 VerifyRegionClosure blk(true, _vo); 3383 _g1h->heap_region_par_iterate_chunked(&blk, worker_id, 3384 _g1h->workers()->active_workers(), 3385 HeapRegion::ParVerifyClaimValue); 3386 if (blk.failures()) { 3387 _failures = true; 3388 } 3389 } 3390 }; 3391 3392 void G1CollectedHeap::verify(bool silent, VerifyOption vo) { 3393 if (SafepointSynchronize::is_at_safepoint()) { 3394 assert(Thread::current()->is_VM_thread(), 3395 "Expected to be executed serially by the VM thread at this point"); 3396 3397 if (!silent) { gclog_or_tty->print("Roots "); } 3398 VerifyRootsClosure rootsCl(vo); 3399 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo); 3400 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl); 3401 VerifyKlassClosure klassCl(this, &rootsCl); 3402 3403 // We apply the relevant closures to all the oops in the 3404 // system dictionary, the string table and the code cache. 3405 const int so = SO_AllClasses | SO_Strings | SO_CodeCache; 3406 3407 // Need cleared claim bits for the strong roots processing 3408 ClassLoaderDataGraph::clear_claimed_marks(); 3409 3410 process_strong_roots(true, // activate StrongRootsScope 3411 false, // we set "is scavenging" to false, 3412 // so we don't reset the dirty cards. 3413 ScanningOption(so), // roots scanning options 3414 &rootsCl, 3415 &blobsCl, 3416 &klassCl 3417 ); 3418 3419 bool failures = rootsCl.failures() || codeRootsCl.failures(); 3420 3421 if (vo != VerifyOption_G1UseMarkWord) { 3422 // If we're verifying during a full GC then the region sets 3423 // will have been torn down at the start of the GC. Therefore 3424 // verifying the region sets will fail. So we only verify 3425 // the region sets when not in a full GC. 3426 if (!silent) { gclog_or_tty->print("HeapRegionSets "); } 3427 verify_region_sets(); 3428 } 3429 3430 if (!silent) { gclog_or_tty->print("HeapRegions "); } 3431 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) { 3432 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue), 3433 "sanity check"); 3434 3435 G1ParVerifyTask task(this, vo); 3436 assert(UseDynamicNumberOfGCThreads || 3437 workers()->active_workers() == workers()->total_workers(), 3438 "If not dynamic should be using all the workers"); 3439 int n_workers = workers()->active_workers(); 3440 set_par_threads(n_workers); 3441 workers()->run_task(&task); 3442 set_par_threads(0); 3443 if (task.failures()) { 3444 failures = true; 3445 } 3446 3447 // Checks that the expected amount of parallel work was done. 3448 // The implication is that n_workers is > 0. 3449 assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue), 3450 "sanity check"); 3451 3452 reset_heap_region_claim_values(); 3453 3454 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue), 3455 "sanity check"); 3456 } else { 3457 VerifyRegionClosure blk(false, vo); 3458 heap_region_iterate(&blk); 3459 if (blk.failures()) { 3460 failures = true; 3461 } 3462 } 3463 if (!silent) gclog_or_tty->print("RemSet "); 3464 rem_set()->verify(); 3465 3466 if (G1StringDedup::is_enabled()) { 3467 if (!silent) gclog_or_tty->print("StrDedup "); 3468 G1StringDedup::verify(); 3469 } 3470 3471 if (failures) { 3472 gclog_or_tty->print_cr("Heap:"); 3473 // It helps to have the per-region information in the output to 3474 // help us track down what went wrong. This is why we call 3475 // print_extended_on() instead of print_on(). 3476 print_extended_on(gclog_or_tty); 3477 gclog_or_tty->cr(); 3478 #ifndef PRODUCT 3479 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) { 3480 concurrent_mark()->print_reachable("at-verification-failure", 3481 vo, false /* all */); 3482 } 3483 #endif 3484 gclog_or_tty->flush(); 3485 } 3486 guarantee(!failures, "there should not have been any failures"); 3487 } else { 3488 if (!silent) { 3489 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet"); 3490 if (G1StringDedup::is_enabled()) { 3491 gclog_or_tty->print(", StrDedup"); 3492 } 3493 gclog_or_tty->print(") "); 3494 } 3495 } 3496 } 3497 3498 void G1CollectedHeap::verify(bool silent) { 3499 verify(silent, VerifyOption_G1UsePrevMarking); 3500 } 3501 3502 double G1CollectedHeap::verify(bool guard, const char* msg) { 3503 double verify_time_ms = 0.0; 3504 3505 if (guard && total_collections() >= VerifyGCStartAt) { 3506 double verify_start = os::elapsedTime(); 3507 HandleMark hm; // Discard invalid handles created during verification 3508 prepare_for_verify(); 3509 Universe::verify(VerifyOption_G1UsePrevMarking, msg); 3510 verify_time_ms = (os::elapsedTime() - verify_start) * 1000; 3511 } 3512 3513 return verify_time_ms; 3514 } 3515 3516 void G1CollectedHeap::verify_before_gc() { 3517 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:"); 3518 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms); 3519 } 3520 3521 void G1CollectedHeap::verify_after_gc() { 3522 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:"); 3523 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms); 3524 } 3525 3526 class PrintRegionClosure: public HeapRegionClosure { 3527 outputStream* _st; 3528 public: 3529 PrintRegionClosure(outputStream* st) : _st(st) {} 3530 bool doHeapRegion(HeapRegion* r) { 3531 r->print_on(_st); 3532 return false; 3533 } 3534 }; 3535 3536 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 3537 const HeapRegion* hr, 3538 const VerifyOption vo) const { 3539 switch (vo) { 3540 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); 3541 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); 3542 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked(); 3543 default: ShouldNotReachHere(); 3544 } 3545 return false; // keep some compilers happy 3546 } 3547 3548 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 3549 const VerifyOption vo) const { 3550 switch (vo) { 3551 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); 3552 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); 3553 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked(); 3554 default: ShouldNotReachHere(); 3555 } 3556 return false; // keep some compilers happy 3557 } 3558 3559 void G1CollectedHeap::print_on(outputStream* st) const { 3560 st->print(" %-20s", "garbage-first heap"); 3561 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 3562 capacity()/K, used_unlocked()/K); 3563 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")", 3564 _g1_storage.low_boundary(), 3565 _g1_storage.high(), 3566 _g1_storage.high_boundary()); 3567 st->cr(); 3568 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); 3569 uint young_regions = _young_list->length(); 3570 st->print("%u young (" SIZE_FORMAT "K), ", young_regions, 3571 (size_t) young_regions * HeapRegion::GrainBytes / K); 3572 uint survivor_regions = g1_policy()->recorded_survivor_regions(); 3573 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, 3574 (size_t) survivor_regions * HeapRegion::GrainBytes / K); 3575 st->cr(); 3576 MetaspaceAux::print_on(st); 3577 } 3578 3579 void G1CollectedHeap::print_extended_on(outputStream* st) const { 3580 print_on(st); 3581 3582 // Print the per-region information. 3583 st->cr(); 3584 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), " 3585 "HS=humongous(starts), HC=humongous(continues), " 3586 "CS=collection set, F=free, TS=gc time stamp, " 3587 "PTAMS=previous top-at-mark-start, " 3588 "NTAMS=next top-at-mark-start)"); 3589 PrintRegionClosure blk(st); 3590 heap_region_iterate(&blk); 3591 } 3592 3593 void G1CollectedHeap::print_on_error(outputStream* st) const { 3594 this->CollectedHeap::print_on_error(st); 3595 3596 if (_cm != NULL) { 3597 st->cr(); 3598 _cm->print_on_error(st); 3599 } 3600 } 3601 3602 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const { 3603 if (G1CollectedHeap::use_parallel_gc_threads()) { 3604 workers()->print_worker_threads_on(st); 3605 } 3606 _cmThread->print_on(st); 3607 st->cr(); 3608 _cm->print_worker_threads_on(st); 3609 _cg1r->print_worker_threads_on(st); 3610 if (G1StringDedup::is_enabled()) { 3611 G1StringDedup::print_worker_threads_on(st); 3612 } 3613 } 3614 3615 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { 3616 if (G1CollectedHeap::use_parallel_gc_threads()) { 3617 workers()->threads_do(tc); 3618 } 3619 tc->do_thread(_cmThread); 3620 _cg1r->threads_do(tc); 3621 if (G1StringDedup::is_enabled()) { 3622 G1StringDedup::threads_do(tc); 3623 } 3624 } 3625 3626 void G1CollectedHeap::print_tracing_info() const { 3627 // We'll overload this to mean "trace GC pause statistics." 3628 if (TraceGen0Time || TraceGen1Time) { 3629 // The "G1CollectorPolicy" is keeping track of these stats, so delegate 3630 // to that. 3631 g1_policy()->print_tracing_info(); 3632 } 3633 if (G1SummarizeRSetStats) { 3634 g1_rem_set()->print_summary_info(); 3635 } 3636 if (G1SummarizeConcMark) { 3637 concurrent_mark()->print_summary_info(); 3638 } 3639 g1_policy()->print_yg_surv_rate_info(); 3640 SpecializationStats::print(); 3641 } 3642 3643 #ifndef PRODUCT 3644 // Helpful for debugging RSet issues. 3645 3646 class PrintRSetsClosure : public HeapRegionClosure { 3647 private: 3648 const char* _msg; 3649 size_t _occupied_sum; 3650 3651 public: 3652 bool doHeapRegion(HeapRegion* r) { 3653 HeapRegionRemSet* hrrs = r->rem_set(); 3654 size_t occupied = hrrs->occupied(); 3655 _occupied_sum += occupied; 3656 3657 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT, 3658 HR_FORMAT_PARAMS(r)); 3659 if (occupied == 0) { 3660 gclog_or_tty->print_cr(" RSet is empty"); 3661 } else { 3662 hrrs->print(); 3663 } 3664 gclog_or_tty->print_cr("----------"); 3665 return false; 3666 } 3667 3668 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { 3669 gclog_or_tty->cr(); 3670 gclog_or_tty->print_cr("========================================"); 3671 gclog_or_tty->print_cr("%s", msg); 3672 gclog_or_tty->cr(); 3673 } 3674 3675 ~PrintRSetsClosure() { 3676 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum); 3677 gclog_or_tty->print_cr("========================================"); 3678 gclog_or_tty->cr(); 3679 } 3680 }; 3681 3682 void G1CollectedHeap::print_cset_rsets() { 3683 PrintRSetsClosure cl("Printing CSet RSets"); 3684 collection_set_iterate(&cl); 3685 } 3686 3687 void G1CollectedHeap::print_all_rsets() { 3688 PrintRSetsClosure cl("Printing All RSets");; 3689 heap_region_iterate(&cl); 3690 } 3691 #endif // PRODUCT 3692 3693 G1CollectedHeap* G1CollectedHeap::heap() { 3694 assert(_sh->kind() == CollectedHeap::G1CollectedHeap, 3695 "not a garbage-first heap"); 3696 return _g1h; 3697 } 3698 3699 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) { 3700 // always_do_update_barrier = false; 3701 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 3702 // Fill TLAB's and such 3703 accumulate_statistics_all_tlabs(); 3704 ensure_parsability(true); 3705 3706 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) && 3707 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) { 3708 g1_rem_set()->print_periodic_summary_info("Before GC RS summary"); 3709 } 3710 } 3711 3712 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) { 3713 3714 if (G1SummarizeRSetStats && 3715 (G1SummarizeRSetStatsPeriod > 0) && 3716 // we are at the end of the GC. Total collections has already been increased. 3717 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) { 3718 g1_rem_set()->print_periodic_summary_info("After GC RS summary"); 3719 } 3720 3721 // FIXME: what is this about? 3722 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" 3723 // is set. 3724 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(), 3725 "derived pointer present")); 3726 // always_do_update_barrier = true; 3727 3728 resize_all_tlabs(); 3729 3730 // We have just completed a GC. Update the soft reference 3731 // policy with the new heap occupancy 3732 Universe::update_heap_info_at_gc(); 3733 } 3734 3735 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, 3736 unsigned int gc_count_before, 3737 bool* succeeded, 3738 GCCause::Cause gc_cause) { 3739 assert_heap_not_locked_and_not_at_safepoint(); 3740 g1_policy()->record_stop_world_start(); 3741 VM_G1IncCollectionPause op(gc_count_before, 3742 word_size, 3743 false, /* should_initiate_conc_mark */ 3744 g1_policy()->max_pause_time_ms(), 3745 gc_cause); 3746 VMThread::execute(&op); 3747 3748 HeapWord* result = op.result(); 3749 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded(); 3750 assert(result == NULL || ret_succeeded, 3751 "the result should be NULL if the VM did not succeed"); 3752 *succeeded = ret_succeeded; 3753 3754 assert_heap_not_locked(); 3755 return result; 3756 } 3757 3758 void 3759 G1CollectedHeap::doConcurrentMark() { 3760 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); 3761 if (!_cmThread->in_progress()) { 3762 _cmThread->set_started(); 3763 CGC_lock->notify(); 3764 } 3765 } 3766 3767 size_t G1CollectedHeap::pending_card_num() { 3768 size_t extra_cards = 0; 3769 JavaThread *curr = Threads::first(); 3770 while (curr != NULL) { 3771 DirtyCardQueue& dcq = curr->dirty_card_queue(); 3772 extra_cards += dcq.size(); 3773 curr = curr->next(); 3774 } 3775 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 3776 size_t buffer_size = dcqs.buffer_size(); 3777 size_t buffer_num = dcqs.completed_buffers_num(); 3778 3779 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes 3780 // in bytes - not the number of 'entries'. We need to convert 3781 // into a number of cards. 3782 return (buffer_size * buffer_num + extra_cards) / oopSize; 3783 } 3784 3785 size_t G1CollectedHeap::cards_scanned() { 3786 return g1_rem_set()->cardsScanned(); 3787 } 3788 3789 void 3790 G1CollectedHeap::setup_surviving_young_words() { 3791 assert(_surviving_young_words == NULL, "pre-condition"); 3792 uint array_length = g1_policy()->young_cset_region_length(); 3793 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC); 3794 if (_surviving_young_words == NULL) { 3795 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR, 3796 "Not enough space for young surv words summary."); 3797 } 3798 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t)); 3799 #ifdef ASSERT 3800 for (uint i = 0; i < array_length; ++i) { 3801 assert( _surviving_young_words[i] == 0, "memset above" ); 3802 } 3803 #endif // !ASSERT 3804 } 3805 3806 void 3807 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) { 3808 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); 3809 uint array_length = g1_policy()->young_cset_region_length(); 3810 for (uint i = 0; i < array_length; ++i) { 3811 _surviving_young_words[i] += surv_young_words[i]; 3812 } 3813 } 3814 3815 void 3816 G1CollectedHeap::cleanup_surviving_young_words() { 3817 guarantee( _surviving_young_words != NULL, "pre-condition" ); 3818 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words, mtGC); 3819 _surviving_young_words = NULL; 3820 } 3821 3822 #ifdef ASSERT 3823 class VerifyCSetClosure: public HeapRegionClosure { 3824 public: 3825 bool doHeapRegion(HeapRegion* hr) { 3826 // Here we check that the CSet region's RSet is ready for parallel 3827 // iteration. The fields that we'll verify are only manipulated 3828 // when the region is part of a CSet and is collected. Afterwards, 3829 // we reset these fields when we clear the region's RSet (when the 3830 // region is freed) so they are ready when the region is 3831 // re-allocated. The only exception to this is if there's an 3832 // evacuation failure and instead of freeing the region we leave 3833 // it in the heap. In that case, we reset these fields during 3834 // evacuation failure handling. 3835 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification"); 3836 3837 // Here's a good place to add any other checks we'd like to 3838 // perform on CSet regions. 3839 return false; 3840 } 3841 }; 3842 #endif // ASSERT 3843 3844 #if TASKQUEUE_STATS 3845 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) { 3846 st->print_raw_cr("GC Task Stats"); 3847 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); 3848 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); 3849 } 3850 3851 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const { 3852 print_taskqueue_stats_hdr(st); 3853 3854 TaskQueueStats totals; 3855 const int n = workers() != NULL ? workers()->total_workers() : 1; 3856 for (int i = 0; i < n; ++i) { 3857 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr(); 3858 totals += task_queue(i)->stats; 3859 } 3860 st->print_raw("tot "); totals.print(st); st->cr(); 3861 3862 DEBUG_ONLY(totals.verify()); 3863 } 3864 3865 void G1CollectedHeap::reset_taskqueue_stats() { 3866 const int n = workers() != NULL ? workers()->total_workers() : 1; 3867 for (int i = 0; i < n; ++i) { 3868 task_queue(i)->stats.reset(); 3869 } 3870 } 3871 #endif // TASKQUEUE_STATS 3872 3873 void G1CollectedHeap::log_gc_header() { 3874 if (!G1Log::fine()) { 3875 return; 3876 } 3877 3878 gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id()); 3879 3880 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause()) 3881 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)") 3882 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : ""); 3883 3884 gclog_or_tty->print("[%s", (const char*)gc_cause_str); 3885 } 3886 3887 void G1CollectedHeap::log_gc_footer(double pause_time_sec) { 3888 if (!G1Log::fine()) { 3889 return; 3890 } 3891 3892 if (G1Log::finer()) { 3893 if (evacuation_failed()) { 3894 gclog_or_tty->print(" (to-space exhausted)"); 3895 } 3896 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec); 3897 g1_policy()->phase_times()->note_gc_end(); 3898 g1_policy()->phase_times()->print(pause_time_sec); 3899 g1_policy()->print_detailed_heap_transition(); 3900 } else { 3901 if (evacuation_failed()) { 3902 gclog_or_tty->print("--"); 3903 } 3904 g1_policy()->print_heap_transition(); 3905 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec); 3906 } 3907 gclog_or_tty->flush(); 3908 } 3909 3910 bool 3911 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { 3912 assert_at_safepoint(true /* should_be_vm_thread */); 3913 guarantee(!is_gc_active(), "collection is not reentrant"); 3914 3915 if (GC_locker::check_active_before_gc()) { 3916 return false; 3917 } 3918 3919 _gc_timer_stw->register_gc_start(); 3920 3921 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start()); 3922 3923 SvcGCMarker sgcm(SvcGCMarker::MINOR); 3924 ResourceMark rm; 3925 3926 print_heap_before_gc(); 3927 trace_heap_before_gc(_gc_tracer_stw); 3928 3929 verify_region_sets_optional(); 3930 verify_dirty_young_regions(); 3931 3932 // This call will decide whether this pause is an initial-mark 3933 // pause. If it is, during_initial_mark_pause() will return true 3934 // for the duration of this pause. 3935 g1_policy()->decide_on_conc_mark_initiation(); 3936 3937 // We do not allow initial-mark to be piggy-backed on a mixed GC. 3938 assert(!g1_policy()->during_initial_mark_pause() || 3939 g1_policy()->gcs_are_young(), "sanity"); 3940 3941 // We also do not allow mixed GCs during marking. 3942 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity"); 3943 3944 // Record whether this pause is an initial mark. When the current 3945 // thread has completed its logging output and it's safe to signal 3946 // the CM thread, the flag's value in the policy has been reset. 3947 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause(); 3948 3949 // Inner scope for scope based logging, timers, and stats collection 3950 { 3951 EvacuationInfo evacuation_info; 3952 3953 if (g1_policy()->during_initial_mark_pause()) { 3954 // We are about to start a marking cycle, so we increment the 3955 // full collection counter. 3956 increment_old_marking_cycles_started(); 3957 register_concurrent_cycle_start(_gc_timer_stw->gc_start()); 3958 } 3959 3960 _gc_tracer_stw->report_yc_type(yc_type()); 3961 3962 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty); 3963 3964 int active_workers = (G1CollectedHeap::use_parallel_gc_threads() ? 3965 workers()->active_workers() : 1); 3966 double pause_start_sec = os::elapsedTime(); 3967 g1_policy()->phase_times()->note_gc_start(active_workers); 3968 log_gc_header(); 3969 3970 TraceCollectorStats tcs(g1mm()->incremental_collection_counters()); 3971 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause()); 3972 3973 // If the secondary_free_list is not empty, append it to the 3974 // free_list. No need to wait for the cleanup operation to finish; 3975 // the region allocation code will check the secondary_free_list 3976 // and wait if necessary. If the G1StressConcRegionFreeing flag is 3977 // set, skip this step so that the region allocation code has to 3978 // get entries from the secondary_free_list. 3979 if (!G1StressConcRegionFreeing) { 3980 append_secondary_free_list_if_not_empty_with_lock(); 3981 } 3982 3983 assert(check_young_list_well_formed(), "young list should be well formed"); 3984 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue), 3985 "sanity check"); 3986 3987 // Don't dynamically change the number of GC threads this early. A value of 3988 // 0 is used to indicate serial work. When parallel work is done, 3989 // it will be set. 3990 3991 { // Call to jvmpi::post_class_unload_events must occur outside of active GC 3992 IsGCActiveMark x; 3993 3994 gc_prologue(false); 3995 increment_total_collections(false /* full gc */); 3996 increment_gc_time_stamp(); 3997 3998 verify_before_gc(); 3999 4000 COMPILER2_PRESENT(DerivedPointerTable::clear()); 4001 4002 // Please see comment in g1CollectedHeap.hpp and 4003 // G1CollectedHeap::ref_processing_init() to see how 4004 // reference processing currently works in G1. 4005 4006 // Enable discovery in the STW reference processor 4007 ref_processor_stw()->enable_discovery(true /*verify_disabled*/, 4008 true /*verify_no_refs*/); 4009 4010 { 4011 // We want to temporarily turn off discovery by the 4012 // CM ref processor, if necessary, and turn it back on 4013 // on again later if we do. Using a scoped 4014 // NoRefDiscovery object will do this. 4015 NoRefDiscovery no_cm_discovery(ref_processor_cm()); 4016 4017 // Forget the current alloc region (we might even choose it to be part 4018 // of the collection set!). 4019 release_mutator_alloc_region(); 4020 4021 // We should call this after we retire the mutator alloc 4022 // region(s) so that all the ALLOC / RETIRE events are generated 4023 // before the start GC event. 4024 _hr_printer.start_gc(false /* full */, (size_t) total_collections()); 4025 4026 // This timing is only used by the ergonomics to handle our pause target. 4027 // It is unclear why this should not include the full pause. We will 4028 // investigate this in CR 7178365. 4029 // 4030 // Preserving the old comment here if that helps the investigation: 4031 // 4032 // The elapsed time induced by the start time below deliberately elides 4033 // the possible verification above. 4034 double sample_start_time_sec = os::elapsedTime(); 4035 4036 #if YOUNG_LIST_VERBOSE 4037 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:"); 4038 _young_list->print(); 4039 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 4040 #endif // YOUNG_LIST_VERBOSE 4041 4042 g1_policy()->record_collection_pause_start(sample_start_time_sec); 4043 4044 double scan_wait_start = os::elapsedTime(); 4045 // We have to wait until the CM threads finish scanning the 4046 // root regions as it's the only way to ensure that all the 4047 // objects on them have been correctly scanned before we start 4048 // moving them during the GC. 4049 bool waited = _cm->root_regions()->wait_until_scan_finished(); 4050 double wait_time_ms = 0.0; 4051 if (waited) { 4052 double scan_wait_end = os::elapsedTime(); 4053 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0; 4054 } 4055 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms); 4056 4057 #if YOUNG_LIST_VERBOSE 4058 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:"); 4059 _young_list->print(); 4060 #endif // YOUNG_LIST_VERBOSE 4061 4062 if (g1_policy()->during_initial_mark_pause()) { 4063 concurrent_mark()->checkpointRootsInitialPre(); 4064 } 4065 4066 #if YOUNG_LIST_VERBOSE 4067 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:"); 4068 _young_list->print(); 4069 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 4070 #endif // YOUNG_LIST_VERBOSE 4071 4072 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info); 4073 4074 _cm->note_start_of_gc(); 4075 // We should not verify the per-thread SATB buffers given that 4076 // we have not filtered them yet (we'll do so during the 4077 // GC). We also call this after finalize_cset() to 4078 // ensure that the CSet has been finalized. 4079 _cm->verify_no_cset_oops(true /* verify_stacks */, 4080 true /* verify_enqueued_buffers */, 4081 false /* verify_thread_buffers */, 4082 true /* verify_fingers */); 4083 4084 if (_hr_printer.is_active()) { 4085 HeapRegion* hr = g1_policy()->collection_set(); 4086 while (hr != NULL) { 4087 G1HRPrinter::RegionType type; 4088 if (!hr->is_young()) { 4089 type = G1HRPrinter::Old; 4090 } else if (hr->is_survivor()) { 4091 type = G1HRPrinter::Survivor; 4092 } else { 4093 type = G1HRPrinter::Eden; 4094 } 4095 _hr_printer.cset(hr); 4096 hr = hr->next_in_collection_set(); 4097 } 4098 } 4099 4100 #ifdef ASSERT 4101 VerifyCSetClosure cl; 4102 collection_set_iterate(&cl); 4103 #endif // ASSERT 4104 4105 setup_surviving_young_words(); 4106 4107 // Initialize the GC alloc regions. 4108 init_gc_alloc_regions(evacuation_info); 4109 4110 // Actually do the work... 4111 evacuate_collection_set(evacuation_info); 4112 4113 // We do this to mainly verify the per-thread SATB buffers 4114 // (which have been filtered by now) since we didn't verify 4115 // them earlier. No point in re-checking the stacks / enqueued 4116 // buffers given that the CSet has not changed since last time 4117 // we checked. 4118 _cm->verify_no_cset_oops(false /* verify_stacks */, 4119 false /* verify_enqueued_buffers */, 4120 true /* verify_thread_buffers */, 4121 true /* verify_fingers */); 4122 4123 free_collection_set(g1_policy()->collection_set(), evacuation_info); 4124 g1_policy()->clear_collection_set(); 4125 4126 cleanup_surviving_young_words(); 4127 4128 // Start a new incremental collection set for the next pause. 4129 g1_policy()->start_incremental_cset_building(); 4130 4131 clear_cset_fast_test(); 4132 4133 _young_list->reset_sampled_info(); 4134 4135 // Don't check the whole heap at this point as the 4136 // GC alloc regions from this pause have been tagged 4137 // as survivors and moved on to the survivor list. 4138 // Survivor regions will fail the !is_young() check. 4139 assert(check_young_list_empty(false /* check_heap */), 4140 "young list should be empty"); 4141 4142 #if YOUNG_LIST_VERBOSE 4143 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:"); 4144 _young_list->print(); 4145 #endif // YOUNG_LIST_VERBOSE 4146 4147 g1_policy()->record_survivor_regions(_young_list->survivor_length(), 4148 _young_list->first_survivor_region(), 4149 _young_list->last_survivor_region()); 4150 4151 _young_list->reset_auxilary_lists(); 4152 4153 if (evacuation_failed()) { 4154 _summary_bytes_used = recalculate_used(); 4155 uint n_queues = MAX2((int)ParallelGCThreads, 1); 4156 for (uint i = 0; i < n_queues; i++) { 4157 if (_evacuation_failed_info_array[i].has_failed()) { 4158 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]); 4159 } 4160 } 4161 } else { 4162 // The "used" of the the collection set have already been subtracted 4163 // when they were freed. Add in the bytes evacuated. 4164 _summary_bytes_used += g1_policy()->bytes_copied_during_gc(); 4165 } 4166 4167 if (g1_policy()->during_initial_mark_pause()) { 4168 // We have to do this before we notify the CM threads that 4169 // they can start working to make sure that all the 4170 // appropriate initialization is done on the CM object. 4171 concurrent_mark()->checkpointRootsInitialPost(); 4172 set_marking_started(); 4173 // Note that we don't actually trigger the CM thread at 4174 // this point. We do that later when we're sure that 4175 // the current thread has completed its logging output. 4176 } 4177 4178 allocate_dummy_regions(); 4179 4180 #if YOUNG_LIST_VERBOSE 4181 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:"); 4182 _young_list->print(); 4183 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 4184 #endif // YOUNG_LIST_VERBOSE 4185 4186 init_mutator_alloc_region(); 4187 4188 { 4189 size_t expand_bytes = g1_policy()->expansion_amount(); 4190 if (expand_bytes > 0) { 4191 size_t bytes_before = capacity(); 4192 // No need for an ergo verbose message here, 4193 // expansion_amount() does this when it returns a value > 0. 4194 if (!expand(expand_bytes)) { 4195 // We failed to expand the heap so let's verify that 4196 // committed/uncommitted amount match the backing store 4197 assert(capacity() == _g1_storage.committed_size(), "committed size mismatch"); 4198 assert(max_capacity() == _g1_storage.reserved_size(), "reserved size mismatch"); 4199 } 4200 } 4201 } 4202 4203 // We redo the verification but now wrt to the new CSet which 4204 // has just got initialized after the previous CSet was freed. 4205 _cm->verify_no_cset_oops(true /* verify_stacks */, 4206 true /* verify_enqueued_buffers */, 4207 true /* verify_thread_buffers */, 4208 true /* verify_fingers */); 4209 _cm->note_end_of_gc(); 4210 4211 // This timing is only used by the ergonomics to handle our pause target. 4212 // It is unclear why this should not include the full pause. We will 4213 // investigate this in CR 7178365. 4214 double sample_end_time_sec = os::elapsedTime(); 4215 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; 4216 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info); 4217 4218 MemoryService::track_memory_usage(); 4219 4220 // In prepare_for_verify() below we'll need to scan the deferred 4221 // update buffers to bring the RSets up-to-date if 4222 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning 4223 // the update buffers we'll probably need to scan cards on the 4224 // regions we just allocated to (i.e., the GC alloc 4225 // regions). However, during the last GC we called 4226 // set_saved_mark() on all the GC alloc regions, so card 4227 // scanning might skip the [saved_mark_word()...top()] area of 4228 // those regions (i.e., the area we allocated objects into 4229 // during the last GC). But it shouldn't. Given that 4230 // saved_mark_word() is conditional on whether the GC time stamp 4231 // on the region is current or not, by incrementing the GC time 4232 // stamp here we invalidate all the GC time stamps on all the 4233 // regions and saved_mark_word() will simply return top() for 4234 // all the regions. This is a nicer way of ensuring this rather 4235 // than iterating over the regions and fixing them. In fact, the 4236 // GC time stamp increment here also ensures that 4237 // saved_mark_word() will return top() between pauses, i.e., 4238 // during concurrent refinement. So we don't need the 4239 // is_gc_active() check to decided which top to use when 4240 // scanning cards (see CR 7039627). 4241 increment_gc_time_stamp(); 4242 4243 verify_after_gc(); 4244 4245 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 4246 ref_processor_stw()->verify_no_references_recorded(); 4247 4248 // CM reference discovery will be re-enabled if necessary. 4249 } 4250 4251 // We should do this after we potentially expand the heap so 4252 // that all the COMMIT events are generated before the end GC 4253 // event, and after we retire the GC alloc regions so that all 4254 // RETIRE events are generated before the end GC event. 4255 _hr_printer.end_gc(false /* full */, (size_t) total_collections()); 4256 4257 if (mark_in_progress()) { 4258 concurrent_mark()->update_g1_committed(); 4259 } 4260 4261 #ifdef TRACESPINNING 4262 ParallelTaskTerminator::print_termination_counts(); 4263 #endif 4264 4265 gc_epilogue(false); 4266 } 4267 4268 // Print the remainder of the GC log output. 4269 log_gc_footer(os::elapsedTime() - pause_start_sec); 4270 4271 // It is not yet to safe to tell the concurrent mark to 4272 // start as we have some optional output below. We don't want the 4273 // output from the concurrent mark thread interfering with this 4274 // logging output either. 4275 4276 _hrs.verify_optional(); 4277 verify_region_sets_optional(); 4278 4279 TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats()); 4280 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); 4281 4282 print_heap_after_gc(); 4283 trace_heap_after_gc(_gc_tracer_stw); 4284 4285 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 4286 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 4287 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 4288 // before any GC notifications are raised. 4289 g1mm()->update_sizes(); 4290 4291 _gc_tracer_stw->report_evacuation_info(&evacuation_info); 4292 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold()); 4293 _gc_timer_stw->register_gc_end(); 4294 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions()); 4295 } 4296 // It should now be safe to tell the concurrent mark thread to start 4297 // without its logging output interfering with the logging output 4298 // that came from the pause. 4299 4300 if (should_start_conc_mark) { 4301 // CAUTION: after the doConcurrentMark() call below, 4302 // the concurrent marking thread(s) could be running 4303 // concurrently with us. Make sure that anything after 4304 // this point does not assume that we are the only GC thread 4305 // running. Note: of course, the actual marking work will 4306 // not start until the safepoint itself is released in 4307 // SuspendibleThreadSet::desynchronize(). 4308 doConcurrentMark(); 4309 } 4310 4311 return true; 4312 } 4313 4314 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose) 4315 { 4316 size_t gclab_word_size; 4317 switch (purpose) { 4318 case GCAllocForSurvived: 4319 gclab_word_size = _survivor_plab_stats.desired_plab_sz(); 4320 break; 4321 case GCAllocForTenured: 4322 gclab_word_size = _old_plab_stats.desired_plab_sz(); 4323 break; 4324 default: 4325 assert(false, "unknown GCAllocPurpose"); 4326 gclab_word_size = _old_plab_stats.desired_plab_sz(); 4327 break; 4328 } 4329 4330 // Prevent humongous PLAB sizes for two reasons: 4331 // * PLABs are allocated using a similar paths as oops, but should 4332 // never be in a humongous region 4333 // * Allowing humongous PLABs needlessly churns the region free lists 4334 return MIN2(_humongous_object_threshold_in_words, gclab_word_size); 4335 } 4336 4337 void G1CollectedHeap::init_mutator_alloc_region() { 4338 assert(_mutator_alloc_region.get() == NULL, "pre-condition"); 4339 _mutator_alloc_region.init(); 4340 } 4341 4342 void G1CollectedHeap::release_mutator_alloc_region() { 4343 _mutator_alloc_region.release(); 4344 assert(_mutator_alloc_region.get() == NULL, "post-condition"); 4345 } 4346 4347 void G1CollectedHeap::init_gc_alloc_regions(EvacuationInfo& evacuation_info) { 4348 assert_at_safepoint(true /* should_be_vm_thread */); 4349 4350 _survivor_gc_alloc_region.init(); 4351 _old_gc_alloc_region.init(); 4352 HeapRegion* retained_region = _retained_old_gc_alloc_region; 4353 _retained_old_gc_alloc_region = NULL; 4354 4355 // We will discard the current GC alloc region if: 4356 // a) it's in the collection set (it can happen!), 4357 // b) it's already full (no point in using it), 4358 // c) it's empty (this means that it was emptied during 4359 // a cleanup and it should be on the free list now), or 4360 // d) it's humongous (this means that it was emptied 4361 // during a cleanup and was added to the free list, but 4362 // has been subsequently used to allocate a humongous 4363 // object that may be less than the region size). 4364 if (retained_region != NULL && 4365 !retained_region->in_collection_set() && 4366 !(retained_region->top() == retained_region->end()) && 4367 !retained_region->is_empty() && 4368 !retained_region->isHumongous()) { 4369 retained_region->set_saved_mark(); 4370 // The retained region was added to the old region set when it was 4371 // retired. We have to remove it now, since we don't allow regions 4372 // we allocate to in the region sets. We'll re-add it later, when 4373 // it's retired again. 4374 _old_set.remove(retained_region); 4375 bool during_im = g1_policy()->during_initial_mark_pause(); 4376 retained_region->note_start_of_copying(during_im); 4377 _old_gc_alloc_region.set(retained_region); 4378 _hr_printer.reuse(retained_region); 4379 evacuation_info.set_alloc_regions_used_before(retained_region->used()); 4380 } 4381 } 4382 4383 void G1CollectedHeap::release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info) { 4384 evacuation_info.set_allocation_regions(_survivor_gc_alloc_region.count() + 4385 _old_gc_alloc_region.count()); 4386 _survivor_gc_alloc_region.release(); 4387 // If we have an old GC alloc region to release, we'll save it in 4388 // _retained_old_gc_alloc_region. If we don't 4389 // _retained_old_gc_alloc_region will become NULL. This is what we 4390 // want either way so no reason to check explicitly for either 4391 // condition. 4392 _retained_old_gc_alloc_region = _old_gc_alloc_region.release(); 4393 4394 if (ResizePLAB) { 4395 _survivor_plab_stats.adjust_desired_plab_sz(no_of_gc_workers); 4396 _old_plab_stats.adjust_desired_plab_sz(no_of_gc_workers); 4397 } 4398 } 4399 4400 void G1CollectedHeap::abandon_gc_alloc_regions() { 4401 assert(_survivor_gc_alloc_region.get() == NULL, "pre-condition"); 4402 assert(_old_gc_alloc_region.get() == NULL, "pre-condition"); 4403 _retained_old_gc_alloc_region = NULL; 4404 } 4405 4406 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) { 4407 _drain_in_progress = false; 4408 set_evac_failure_closure(cl); 4409 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true); 4410 } 4411 4412 void G1CollectedHeap::finalize_for_evac_failure() { 4413 assert(_evac_failure_scan_stack != NULL && 4414 _evac_failure_scan_stack->length() == 0, 4415 "Postcondition"); 4416 assert(!_drain_in_progress, "Postcondition"); 4417 delete _evac_failure_scan_stack; 4418 _evac_failure_scan_stack = NULL; 4419 } 4420 4421 void G1CollectedHeap::remove_self_forwarding_pointers() { 4422 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity"); 4423 4424 double remove_self_forwards_start = os::elapsedTime(); 4425 4426 G1ParRemoveSelfForwardPtrsTask rsfp_task(this); 4427 4428 if (G1CollectedHeap::use_parallel_gc_threads()) { 4429 set_par_threads(); 4430 workers()->run_task(&rsfp_task); 4431 set_par_threads(0); 4432 } else { 4433 rsfp_task.work(0); 4434 } 4435 4436 assert(check_cset_heap_region_claim_values(HeapRegion::ParEvacFailureClaimValue), "sanity"); 4437 4438 // Reset the claim values in the regions in the collection set. 4439 reset_cset_heap_region_claim_values(); 4440 4441 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity"); 4442 4443 // Now restore saved marks, if any. 4444 assert(_objs_with_preserved_marks.size() == 4445 _preserved_marks_of_objs.size(), "Both or none."); 4446 while (!_objs_with_preserved_marks.is_empty()) { 4447 oop obj = _objs_with_preserved_marks.pop(); 4448 markOop m = _preserved_marks_of_objs.pop(); 4449 obj->set_mark(m); 4450 } 4451 _objs_with_preserved_marks.clear(true); 4452 _preserved_marks_of_objs.clear(true); 4453 4454 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0); 4455 } 4456 4457 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) { 4458 _evac_failure_scan_stack->push(obj); 4459 } 4460 4461 void G1CollectedHeap::drain_evac_failure_scan_stack() { 4462 assert(_evac_failure_scan_stack != NULL, "precondition"); 4463 4464 while (_evac_failure_scan_stack->length() > 0) { 4465 oop obj = _evac_failure_scan_stack->pop(); 4466 _evac_failure_closure->set_region(heap_region_containing(obj)); 4467 obj->oop_iterate_backwards(_evac_failure_closure); 4468 } 4469 } 4470 4471 oop 4472 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state, 4473 oop old) { 4474 assert(obj_in_cs(old), 4475 err_msg("obj: "PTR_FORMAT" should still be in the CSet", 4476 (HeapWord*) old)); 4477 markOop m = old->mark(); 4478 oop forward_ptr = old->forward_to_atomic(old); 4479 if (forward_ptr == NULL) { 4480 // Forward-to-self succeeded. 4481 assert(_par_scan_state != NULL, "par scan state"); 4482 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure(); 4483 uint queue_num = _par_scan_state->queue_num(); 4484 4485 _evacuation_failed = true; 4486 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size()); 4487 if (_evac_failure_closure != cl) { 4488 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag); 4489 assert(!_drain_in_progress, 4490 "Should only be true while someone holds the lock."); 4491 // Set the global evac-failure closure to the current thread's. 4492 assert(_evac_failure_closure == NULL, "Or locking has failed."); 4493 set_evac_failure_closure(cl); 4494 // Now do the common part. 4495 handle_evacuation_failure_common(old, m); 4496 // Reset to NULL. 4497 set_evac_failure_closure(NULL); 4498 } else { 4499 // The lock is already held, and this is recursive. 4500 assert(_drain_in_progress, "This should only be the recursive case."); 4501 handle_evacuation_failure_common(old, m); 4502 } 4503 return old; 4504 } else { 4505 // Forward-to-self failed. Either someone else managed to allocate 4506 // space for this object (old != forward_ptr) or they beat us in 4507 // self-forwarding it (old == forward_ptr). 4508 assert(old == forward_ptr || !obj_in_cs(forward_ptr), 4509 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" " 4510 "should not be in the CSet", 4511 (HeapWord*) old, (HeapWord*) forward_ptr)); 4512 return forward_ptr; 4513 } 4514 } 4515 4516 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) { 4517 preserve_mark_if_necessary(old, m); 4518 4519 HeapRegion* r = heap_region_containing(old); 4520 if (!r->evacuation_failed()) { 4521 r->set_evacuation_failed(true); 4522 _hr_printer.evac_failure(r); 4523 } 4524 4525 push_on_evac_failure_scan_stack(old); 4526 4527 if (!_drain_in_progress) { 4528 // prevent recursion in copy_to_survivor_space() 4529 _drain_in_progress = true; 4530 drain_evac_failure_scan_stack(); 4531 _drain_in_progress = false; 4532 } 4533 } 4534 4535 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) { 4536 assert(evacuation_failed(), "Oversaving!"); 4537 // We want to call the "for_promotion_failure" version only in the 4538 // case of a promotion failure. 4539 if (m->must_be_preserved_for_promotion_failure(obj)) { 4540 _objs_with_preserved_marks.push(obj); 4541 _preserved_marks_of_objs.push(m); 4542 } 4543 } 4544 4545 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose, 4546 size_t word_size) { 4547 if (purpose == GCAllocForSurvived) { 4548 HeapWord* result = survivor_attempt_allocation(word_size); 4549 if (result != NULL) { 4550 return result; 4551 } else { 4552 // Let's try to allocate in the old gen in case we can fit the 4553 // object there. 4554 return old_attempt_allocation(word_size); 4555 } 4556 } else { 4557 assert(purpose == GCAllocForTenured, "sanity"); 4558 HeapWord* result = old_attempt_allocation(word_size); 4559 if (result != NULL) { 4560 return result; 4561 } else { 4562 // Let's try to allocate in the survivors in case we can fit the 4563 // object there. 4564 return survivor_attempt_allocation(word_size); 4565 } 4566 } 4567 4568 ShouldNotReachHere(); 4569 // Trying to keep some compilers happy. 4570 return NULL; 4571 } 4572 4573 G1ParGCAllocBuffer::G1ParGCAllocBuffer(size_t gclab_word_size) : 4574 ParGCAllocBuffer(gclab_word_size), _retired(false) { } 4575 4576 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num, ReferenceProcessor* rp) 4577 : _g1h(g1h), 4578 _refs(g1h->task_queue(queue_num)), 4579 _dcq(&g1h->dirty_card_queue_set()), 4580 _ct_bs(g1h->g1_barrier_set()), 4581 _g1_rem(g1h->g1_rem_set()), 4582 _hash_seed(17), _queue_num(queue_num), 4583 _term_attempts(0), 4584 _surviving_alloc_buffer(g1h->desired_plab_sz(GCAllocForSurvived)), 4585 _tenured_alloc_buffer(g1h->desired_plab_sz(GCAllocForTenured)), 4586 _age_table(false), _scanner(g1h, this, rp), 4587 _strong_roots_time(0), _term_time(0), 4588 _alloc_buffer_waste(0), _undo_waste(0) { 4589 // we allocate G1YoungSurvRateNumRegions plus one entries, since 4590 // we "sacrifice" entry 0 to keep track of surviving bytes for 4591 // non-young regions (where the age is -1) 4592 // We also add a few elements at the beginning and at the end in 4593 // an attempt to eliminate cache contention 4594 uint real_length = 1 + _g1h->g1_policy()->young_cset_region_length(); 4595 uint array_length = PADDING_ELEM_NUM + 4596 real_length + 4597 PADDING_ELEM_NUM; 4598 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length, mtGC); 4599 if (_surviving_young_words_base == NULL) 4600 vm_exit_out_of_memory(array_length * sizeof(size_t), OOM_MALLOC_ERROR, 4601 "Not enough space for young surv histo."); 4602 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM; 4603 memset(_surviving_young_words, 0, (size_t) real_length * sizeof(size_t)); 4604 4605 _alloc_buffers[GCAllocForSurvived] = &_surviving_alloc_buffer; 4606 _alloc_buffers[GCAllocForTenured] = &_tenured_alloc_buffer; 4607 4608 _start = os::elapsedTime(); 4609 } 4610 4611 void 4612 G1ParScanThreadState::print_termination_stats_hdr(outputStream* const st) 4613 { 4614 st->print_raw_cr("GC Termination Stats"); 4615 st->print_raw_cr(" elapsed --strong roots-- -------termination-------" 4616 " ------waste (KiB)------"); 4617 st->print_raw_cr("thr ms ms % ms % attempts" 4618 " total alloc undo"); 4619 st->print_raw_cr("--- --------- --------- ------ --------- ------ --------" 4620 " ------- ------- -------"); 4621 } 4622 4623 void 4624 G1ParScanThreadState::print_termination_stats(int i, 4625 outputStream* const st) const 4626 { 4627 const double elapsed_ms = elapsed_time() * 1000.0; 4628 const double s_roots_ms = strong_roots_time() * 1000.0; 4629 const double term_ms = term_time() * 1000.0; 4630 st->print_cr("%3d %9.2f %9.2f %6.2f " 4631 "%9.2f %6.2f " SIZE_FORMAT_W(8) " " 4632 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7), 4633 i, elapsed_ms, s_roots_ms, s_roots_ms * 100 / elapsed_ms, 4634 term_ms, term_ms * 100 / elapsed_ms, term_attempts(), 4635 (alloc_buffer_waste() + undo_waste()) * HeapWordSize / K, 4636 alloc_buffer_waste() * HeapWordSize / K, 4637 undo_waste() * HeapWordSize / K); 4638 } 4639 4640 #ifdef ASSERT 4641 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const { 4642 assert(ref != NULL, "invariant"); 4643 assert(UseCompressedOops, "sanity"); 4644 assert(!has_partial_array_mask(ref), err_msg("ref=" PTR_FORMAT, ref)); 4645 oop p = oopDesc::load_decode_heap_oop(ref); 4646 assert(_g1h->is_in_g1_reserved(p), 4647 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p)); 4648 return true; 4649 } 4650 4651 bool G1ParScanThreadState::verify_ref(oop* ref) const { 4652 assert(ref != NULL, "invariant"); 4653 if (has_partial_array_mask(ref)) { 4654 // Must be in the collection set--it's already been copied. 4655 oop p = clear_partial_array_mask(ref); 4656 assert(_g1h->obj_in_cs(p), 4657 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p)); 4658 } else { 4659 oop p = oopDesc::load_decode_heap_oop(ref); 4660 assert(_g1h->is_in_g1_reserved(p), 4661 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p)); 4662 } 4663 return true; 4664 } 4665 4666 bool G1ParScanThreadState::verify_task(StarTask ref) const { 4667 if (ref.is_narrow()) { 4668 return verify_ref((narrowOop*) ref); 4669 } else { 4670 return verify_ref((oop*) ref); 4671 } 4672 } 4673 #endif // ASSERT 4674 4675 void G1ParScanThreadState::trim_queue() { 4676 assert(_evac_failure_cl != NULL, "not set"); 4677 4678 StarTask ref; 4679 do { 4680 // Drain the overflow stack first, so other threads can steal. 4681 while (refs()->pop_overflow(ref)) { 4682 deal_with_reference(ref); 4683 } 4684 4685 while (refs()->pop_local(ref)) { 4686 deal_with_reference(ref); 4687 } 4688 } while (!refs()->is_empty()); 4689 } 4690 4691 G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1, 4692 G1ParScanThreadState* par_scan_state) : 4693 _g1(g1), _par_scan_state(par_scan_state), 4694 _worker_id(par_scan_state->queue_num()) { } 4695 4696 void G1ParCopyHelper::mark_object(oop obj) { 4697 #ifdef ASSERT 4698 HeapRegion* hr = _g1->heap_region_containing(obj); 4699 assert(hr != NULL, "sanity"); 4700 assert(!hr->in_collection_set(), "should not mark objects in the CSet"); 4701 #endif // ASSERT 4702 4703 // We know that the object is not moving so it's safe to read its size. 4704 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id); 4705 } 4706 4707 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) { 4708 #ifdef ASSERT 4709 assert(from_obj->is_forwarded(), "from obj should be forwarded"); 4710 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee"); 4711 assert(from_obj != to_obj, "should not be self-forwarded"); 4712 4713 HeapRegion* from_hr = _g1->heap_region_containing(from_obj); 4714 assert(from_hr != NULL, "sanity"); 4715 assert(from_hr->in_collection_set(), "from obj should be in the CSet"); 4716 4717 HeapRegion* to_hr = _g1->heap_region_containing(to_obj); 4718 assert(to_hr != NULL, "sanity"); 4719 assert(!to_hr->in_collection_set(), "should not mark objects in the CSet"); 4720 #endif // ASSERT 4721 4722 // The object might be in the process of being copied by another 4723 // worker so we cannot trust that its to-space image is 4724 // well-formed. So we have to read its size from its from-space 4725 // image which we know should not be changing. 4726 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id); 4727 } 4728 4729 oop G1ParScanThreadState::copy_to_survivor_space(oop const old) { 4730 size_t word_sz = old->size(); 4731 HeapRegion* from_region = _g1h->heap_region_containing_raw(old); 4732 // +1 to make the -1 indexes valid... 4733 int young_index = from_region->young_index_in_cset()+1; 4734 assert( (from_region->is_young() && young_index > 0) || 4735 (!from_region->is_young() && young_index == 0), "invariant" ); 4736 G1CollectorPolicy* g1p = _g1h->g1_policy(); 4737 markOop m = old->mark(); 4738 int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age() 4739 : m->age(); 4740 GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age, 4741 word_sz); 4742 HeapWord* obj_ptr = allocate(alloc_purpose, word_sz); 4743 #ifndef PRODUCT 4744 // Should this evacuation fail? 4745 if (_g1h->evacuation_should_fail()) { 4746 if (obj_ptr != NULL) { 4747 undo_allocation(alloc_purpose, obj_ptr, word_sz); 4748 obj_ptr = NULL; 4749 } 4750 } 4751 #endif // !PRODUCT 4752 4753 if (obj_ptr == NULL) { 4754 // This will either forward-to-self, or detect that someone else has 4755 // installed a forwarding pointer. 4756 return _g1h->handle_evacuation_failure_par(this, old); 4757 } 4758 4759 oop obj = oop(obj_ptr); 4760 4761 // We're going to allocate linearly, so might as well prefetch ahead. 4762 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes); 4763 4764 oop forward_ptr = old->forward_to_atomic(obj); 4765 if (forward_ptr == NULL) { 4766 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz); 4767 4768 // alloc_purpose is just a hint to allocate() above, recheck the type of region 4769 // we actually allocated from and update alloc_purpose accordingly 4770 HeapRegion* to_region = _g1h->heap_region_containing_raw(obj_ptr); 4771 alloc_purpose = to_region->is_young() ? GCAllocForSurvived : GCAllocForTenured; 4772 4773 if (g1p->track_object_age(alloc_purpose)) { 4774 // We could simply do obj->incr_age(). However, this causes a 4775 // performance issue. obj->incr_age() will first check whether 4776 // the object has a displaced mark by checking its mark word; 4777 // getting the mark word from the new location of the object 4778 // stalls. So, given that we already have the mark word and we 4779 // are about to install it anyway, it's better to increase the 4780 // age on the mark word, when the object does not have a 4781 // displaced mark word. We're not expecting many objects to have 4782 // a displaced marked word, so that case is not optimized 4783 // further (it could be...) and we simply call obj->incr_age(). 4784 4785 if (m->has_displaced_mark_helper()) { 4786 // in this case, we have to install the mark word first, 4787 // otherwise obj looks to be forwarded (the old mark word, 4788 // which contains the forward pointer, was copied) 4789 obj->set_mark(m); 4790 obj->incr_age(); 4791 } else { 4792 m = m->incr_age(); 4793 obj->set_mark(m); 4794 } 4795 age_table()->add(obj, word_sz); 4796 } else { 4797 obj->set_mark(m); 4798 } 4799 4800 if (G1StringDedup::is_enabled()) { 4801 G1StringDedup::enqueue_from_evacuation(from_region->is_young(), 4802 to_region->is_young(), 4803 queue_num(), 4804 obj); 4805 } 4806 4807 size_t* surv_young_words = surviving_young_words(); 4808 surv_young_words[young_index] += word_sz; 4809 4810 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) { 4811 // We keep track of the next start index in the length field of 4812 // the to-space object. The actual length can be found in the 4813 // length field of the from-space object. 4814 arrayOop(obj)->set_length(0); 4815 oop* old_p = set_partial_array_mask(old); 4816 push_on_queue(old_p); 4817 } else { 4818 // No point in using the slower heap_region_containing() method, 4819 // given that we know obj is in the heap. 4820 _scanner.set_region(_g1h->heap_region_containing_raw(obj)); 4821 obj->oop_iterate_backwards(&_scanner); 4822 } 4823 } else { 4824 undo_allocation(alloc_purpose, obj_ptr, word_sz); 4825 obj = forward_ptr; 4826 } 4827 return obj; 4828 } 4829 4830 template <class T> 4831 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) { 4832 if (_g1->heap_region_containing_raw(new_obj)->is_young()) { 4833 _scanned_klass->record_modified_oops(); 4834 } 4835 } 4836 4837 template <G1Barrier barrier, bool do_mark_object> 4838 template <class T> 4839 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) { 4840 T heap_oop = oopDesc::load_heap_oop(p); 4841 4842 if (oopDesc::is_null(heap_oop)) { 4843 return; 4844 } 4845 4846 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 4847 4848 assert(_worker_id == _par_scan_state->queue_num(), "sanity"); 4849 4850 if (_g1->in_cset_fast_test(obj)) { 4851 oop forwardee; 4852 if (obj->is_forwarded()) { 4853 forwardee = obj->forwardee(); 4854 } else { 4855 forwardee = _par_scan_state->copy_to_survivor_space(obj); 4856 } 4857 assert(forwardee != NULL, "forwardee should not be NULL"); 4858 oopDesc::encode_store_heap_oop(p, forwardee); 4859 if (do_mark_object && forwardee != obj) { 4860 // If the object is self-forwarded we don't need to explicitly 4861 // mark it, the evacuation failure protocol will do so. 4862 mark_forwarded_object(obj, forwardee); 4863 } 4864 4865 if (barrier == G1BarrierKlass) { 4866 do_klass_barrier(p, forwardee); 4867 } 4868 } else { 4869 // The object is not in collection set. If we're a root scanning 4870 // closure during an initial mark pause (i.e. do_mark_object will 4871 // be true) then attempt to mark the object. 4872 if (do_mark_object) { 4873 mark_object(obj); 4874 } 4875 } 4876 4877 if (barrier == G1BarrierEvac) { 4878 _par_scan_state->update_rs(_from, p, _worker_id); 4879 } 4880 } 4881 4882 template void G1ParCopyClosure<G1BarrierEvac, false>::do_oop_work(oop* p); 4883 template void G1ParCopyClosure<G1BarrierEvac, false>::do_oop_work(narrowOop* p); 4884 4885 class G1ParEvacuateFollowersClosure : public VoidClosure { 4886 protected: 4887 G1CollectedHeap* _g1h; 4888 G1ParScanThreadState* _par_scan_state; 4889 RefToScanQueueSet* _queues; 4890 ParallelTaskTerminator* _terminator; 4891 4892 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 4893 RefToScanQueueSet* queues() { return _queues; } 4894 ParallelTaskTerminator* terminator() { return _terminator; } 4895 4896 public: 4897 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h, 4898 G1ParScanThreadState* par_scan_state, 4899 RefToScanQueueSet* queues, 4900 ParallelTaskTerminator* terminator) 4901 : _g1h(g1h), _par_scan_state(par_scan_state), 4902 _queues(queues), _terminator(terminator) {} 4903 4904 void do_void(); 4905 4906 private: 4907 inline bool offer_termination(); 4908 }; 4909 4910 bool G1ParEvacuateFollowersClosure::offer_termination() { 4911 G1ParScanThreadState* const pss = par_scan_state(); 4912 pss->start_term_time(); 4913 const bool res = terminator()->offer_termination(); 4914 pss->end_term_time(); 4915 return res; 4916 } 4917 4918 void G1ParEvacuateFollowersClosure::do_void() { 4919 StarTask stolen_task; 4920 G1ParScanThreadState* const pss = par_scan_state(); 4921 pss->trim_queue(); 4922 4923 do { 4924 while (queues()->steal(pss->queue_num(), pss->hash_seed(), stolen_task)) { 4925 assert(pss->verify_task(stolen_task), "sanity"); 4926 if (stolen_task.is_narrow()) { 4927 pss->deal_with_reference((narrowOop*) stolen_task); 4928 } else { 4929 pss->deal_with_reference((oop*) stolen_task); 4930 } 4931 4932 // We've just processed a reference and we might have made 4933 // available new entries on the queues. So we have to make sure 4934 // we drain the queues as necessary. 4935 pss->trim_queue(); 4936 } 4937 } while (!offer_termination()); 4938 4939 pss->retire_alloc_buffers(); 4940 } 4941 4942 class G1KlassScanClosure : public KlassClosure { 4943 G1ParCopyHelper* _closure; 4944 bool _process_only_dirty; 4945 int _count; 4946 public: 4947 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty) 4948 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {} 4949 void do_klass(Klass* klass) { 4950 // If the klass has not been dirtied we know that there's 4951 // no references into the young gen and we can skip it. 4952 if (!_process_only_dirty || klass->has_modified_oops()) { 4953 // Clean the klass since we're going to scavenge all the metadata. 4954 klass->clear_modified_oops(); 4955 4956 // Tell the closure that this klass is the Klass to scavenge 4957 // and is the one to dirty if oops are left pointing into the young gen. 4958 _closure->set_scanned_klass(klass); 4959 4960 klass->oops_do(_closure); 4961 4962 _closure->set_scanned_klass(NULL); 4963 } 4964 _count++; 4965 } 4966 }; 4967 4968 class G1ParTask : public AbstractGangTask { 4969 protected: 4970 G1CollectedHeap* _g1h; 4971 RefToScanQueueSet *_queues; 4972 ParallelTaskTerminator _terminator; 4973 uint _n_workers; 4974 4975 Mutex _stats_lock; 4976 Mutex* stats_lock() { return &_stats_lock; } 4977 4978 size_t getNCards() { 4979 return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1) 4980 / G1BlockOffsetSharedArray::N_bytes; 4981 } 4982 4983 public: 4984 G1ParTask(G1CollectedHeap* g1h, 4985 RefToScanQueueSet *task_queues) 4986 : AbstractGangTask("G1 collection"), 4987 _g1h(g1h), 4988 _queues(task_queues), 4989 _terminator(0, _queues), 4990 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true) 4991 {} 4992 4993 RefToScanQueueSet* queues() { return _queues; } 4994 4995 RefToScanQueue *work_queue(int i) { 4996 return queues()->queue(i); 4997 } 4998 4999 ParallelTaskTerminator* terminator() { return &_terminator; } 5000 5001 virtual void set_for_termination(int active_workers) { 5002 // This task calls set_n_termination() in par_non_clean_card_iterate_work() 5003 // in the young space (_par_seq_tasks) in the G1 heap 5004 // for SequentialSubTasksDone. 5005 // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap 5006 // both of which need setting by set_n_termination(). 5007 _g1h->SharedHeap::set_n_termination(active_workers); 5008 _g1h->set_n_termination(active_workers); 5009 terminator()->reset_for_reuse(active_workers); 5010 _n_workers = active_workers; 5011 } 5012 5013 void work(uint worker_id) { 5014 if (worker_id >= _n_workers) return; // no work needed this round 5015 5016 double start_time_ms = os::elapsedTime() * 1000.0; 5017 _g1h->g1_policy()->phase_times()->record_gc_worker_start_time(worker_id, start_time_ms); 5018 5019 { 5020 ResourceMark rm; 5021 HandleMark hm; 5022 5023 ReferenceProcessor* rp = _g1h->ref_processor_stw(); 5024 5025 G1ParScanThreadState pss(_g1h, worker_id, rp); 5026 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp); 5027 5028 pss.set_evac_failure_closure(&evac_failure_cl); 5029 5030 G1ParScanExtRootClosure only_scan_root_cl(_g1h, &pss, rp); 5031 G1ParScanMetadataClosure only_scan_metadata_cl(_g1h, &pss, rp); 5032 5033 G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss, rp); 5034 G1ParScanAndMarkMetadataClosure scan_mark_metadata_cl(_g1h, &pss, rp); 5035 5036 bool only_young = _g1h->g1_policy()->gcs_are_young(); 5037 G1KlassScanClosure scan_mark_klasses_cl_s(&scan_mark_metadata_cl, false); 5038 G1KlassScanClosure only_scan_klasses_cl_s(&only_scan_metadata_cl, only_young); 5039 5040 OopClosure* scan_root_cl = &only_scan_root_cl; 5041 G1KlassScanClosure* scan_klasses_cl = &only_scan_klasses_cl_s; 5042 5043 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5044 // We also need to mark copied objects. 5045 scan_root_cl = &scan_mark_root_cl; 5046 scan_klasses_cl = &scan_mark_klasses_cl_s; 5047 } 5048 5049 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss); 5050 5051 // Don't scan the scavengable methods in the code cache as part 5052 // of strong root scanning. The code roots that point into a 5053 // region in the collection set are scanned when we scan the 5054 // region's RSet. 5055 int so = SharedHeap::SO_AllClasses | SharedHeap::SO_Strings; 5056 5057 pss.start_strong_roots(); 5058 _g1h->g1_process_strong_roots(/* is scavenging */ true, 5059 SharedHeap::ScanningOption(so), 5060 scan_root_cl, 5061 &push_heap_rs_cl, 5062 scan_klasses_cl, 5063 worker_id); 5064 pss.end_strong_roots(); 5065 5066 { 5067 double start = os::elapsedTime(); 5068 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator); 5069 evac.do_void(); 5070 double elapsed_ms = (os::elapsedTime()-start)*1000.0; 5071 double term_ms = pss.term_time()*1000.0; 5072 _g1h->g1_policy()->phase_times()->add_obj_copy_time(worker_id, elapsed_ms-term_ms); 5073 _g1h->g1_policy()->phase_times()->record_termination(worker_id, term_ms, pss.term_attempts()); 5074 } 5075 _g1h->g1_policy()->record_thread_age_table(pss.age_table()); 5076 _g1h->update_surviving_young_words(pss.surviving_young_words()+1); 5077 5078 if (ParallelGCVerbose) { 5079 MutexLocker x(stats_lock()); 5080 pss.print_termination_stats(worker_id); 5081 } 5082 5083 assert(pss.refs()->is_empty(), "should be empty"); 5084 5085 // Close the inner scope so that the ResourceMark and HandleMark 5086 // destructors are executed here and are included as part of the 5087 // "GC Worker Time". 5088 } 5089 5090 double end_time_ms = os::elapsedTime() * 1000.0; 5091 _g1h->g1_policy()->phase_times()->record_gc_worker_end_time(worker_id, end_time_ms); 5092 } 5093 }; 5094 5095 // *** Common G1 Evacuation Stuff 5096 5097 // This method is run in a GC worker. 5098 5099 void 5100 G1CollectedHeap:: 5101 g1_process_strong_roots(bool is_scavenging, 5102 ScanningOption so, 5103 OopClosure* scan_non_heap_roots, 5104 OopsInHeapRegionClosure* scan_rs, 5105 G1KlassScanClosure* scan_klasses, 5106 uint worker_i) { 5107 5108 // First scan the strong roots 5109 double ext_roots_start = os::elapsedTime(); 5110 double closure_app_time_sec = 0.0; 5111 5112 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots); 5113 5114 assert(so & SO_CodeCache || scan_rs != NULL, "must scan code roots somehow"); 5115 // Walk the code cache/strong code roots w/o buffering, because StarTask 5116 // cannot handle unaligned oop locations. 5117 CodeBlobToOopClosure eager_scan_code_roots(scan_non_heap_roots, true /* do_marking */); 5118 5119 process_strong_roots(false, // no scoping; this is parallel code 5120 is_scavenging, so, 5121 &buf_scan_non_heap_roots, 5122 &eager_scan_code_roots, 5123 scan_klasses 5124 ); 5125 5126 // Now the CM ref_processor roots. 5127 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) { 5128 // We need to treat the discovered reference lists of the 5129 // concurrent mark ref processor as roots and keep entries 5130 // (which are added by the marking threads) on them live 5131 // until they can be processed at the end of marking. 5132 ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots); 5133 } 5134 5135 // Finish up any enqueued closure apps (attributed as object copy time). 5136 buf_scan_non_heap_roots.done(); 5137 5138 double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds(); 5139 5140 g1_policy()->phase_times()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0); 5141 5142 double ext_root_time_ms = 5143 ((os::elapsedTime() - ext_roots_start) - obj_copy_time_sec) * 1000.0; 5144 5145 g1_policy()->phase_times()->record_ext_root_scan_time(worker_i, ext_root_time_ms); 5146 5147 // During conc marking we have to filter the per-thread SATB buffers 5148 // to make sure we remove any oops into the CSet (which will show up 5149 // as implicitly live). 5150 double satb_filtering_ms = 0.0; 5151 if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers)) { 5152 if (mark_in_progress()) { 5153 double satb_filter_start = os::elapsedTime(); 5154 5155 JavaThread::satb_mark_queue_set().filter_thread_buffers(); 5156 5157 satb_filtering_ms = (os::elapsedTime() - satb_filter_start) * 1000.0; 5158 } 5159 } 5160 g1_policy()->phase_times()->record_satb_filtering_time(worker_i, satb_filtering_ms); 5161 5162 // If this is an initial mark pause, and we're not scanning 5163 // the entire code cache, we need to mark the oops in the 5164 // strong code root lists for the regions that are not in 5165 // the collection set. 5166 // Note all threads participate in this set of root tasks. 5167 double mark_strong_code_roots_ms = 0.0; 5168 if (g1_policy()->during_initial_mark_pause() && !(so & SO_CodeCache)) { 5169 double mark_strong_roots_start = os::elapsedTime(); 5170 mark_strong_code_roots(worker_i); 5171 mark_strong_code_roots_ms = (os::elapsedTime() - mark_strong_roots_start) * 1000.0; 5172 } 5173 g1_policy()->phase_times()->record_strong_code_root_mark_time(worker_i, mark_strong_code_roots_ms); 5174 5175 // Now scan the complement of the collection set. 5176 if (scan_rs != NULL) { 5177 g1_rem_set()->oops_into_collection_set_do(scan_rs, &eager_scan_code_roots, worker_i); 5178 } 5179 _process_strong_tasks->all_tasks_completed(); 5180 } 5181 5182 void 5183 G1CollectedHeap::g1_process_weak_roots(OopClosure* root_closure) { 5184 CodeBlobToOopClosure roots_in_blobs(root_closure, /*do_marking=*/ false); 5185 SharedHeap::process_weak_roots(root_closure, &roots_in_blobs); 5186 } 5187 5188 class G1StringSymbolTableUnlinkTask : public AbstractGangTask { 5189 private: 5190 BoolObjectClosure* _is_alive; 5191 int _initial_string_table_size; 5192 int _initial_symbol_table_size; 5193 5194 bool _process_strings; 5195 int _strings_processed; 5196 int _strings_removed; 5197 5198 bool _process_symbols; 5199 int _symbols_processed; 5200 int _symbols_removed; 5201 5202 bool _do_in_parallel; 5203 public: 5204 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) : 5205 AbstractGangTask("Par String/Symbol table unlink"), _is_alive(is_alive), 5206 _do_in_parallel(G1CollectedHeap::use_parallel_gc_threads()), 5207 _process_strings(process_strings), _strings_processed(0), _strings_removed(0), 5208 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) { 5209 5210 _initial_string_table_size = StringTable::the_table()->table_size(); 5211 _initial_symbol_table_size = SymbolTable::the_table()->table_size(); 5212 if (process_strings) { 5213 StringTable::clear_parallel_claimed_index(); 5214 } 5215 if (process_symbols) { 5216 SymbolTable::clear_parallel_claimed_index(); 5217 } 5218 } 5219 5220 ~G1StringSymbolTableUnlinkTask() { 5221 guarantee(!_process_strings || !_do_in_parallel || StringTable::parallel_claimed_index() >= _initial_string_table_size, 5222 err_msg("claim value "INT32_FORMAT" after unlink less than initial string table size "INT32_FORMAT, 5223 StringTable::parallel_claimed_index(), _initial_string_table_size)); 5224 guarantee(!_process_symbols || !_do_in_parallel || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size, 5225 err_msg("claim value "INT32_FORMAT" after unlink less than initial symbol table size "INT32_FORMAT, 5226 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size)); 5227 } 5228 5229 void work(uint worker_id) { 5230 if (_do_in_parallel) { 5231 int strings_processed = 0; 5232 int strings_removed = 0; 5233 int symbols_processed = 0; 5234 int symbols_removed = 0; 5235 if (_process_strings) { 5236 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed); 5237 Atomic::add(strings_processed, &_strings_processed); 5238 Atomic::add(strings_removed, &_strings_removed); 5239 } 5240 if (_process_symbols) { 5241 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed); 5242 Atomic::add(symbols_processed, &_symbols_processed); 5243 Atomic::add(symbols_removed, &_symbols_removed); 5244 } 5245 } else { 5246 if (_process_strings) { 5247 StringTable::unlink(_is_alive, &_strings_processed, &_strings_removed); 5248 } 5249 if (_process_symbols) { 5250 SymbolTable::unlink(&_symbols_processed, &_symbols_removed); 5251 } 5252 } 5253 } 5254 5255 size_t strings_processed() const { return (size_t)_strings_processed; } 5256 size_t strings_removed() const { return (size_t)_strings_removed; } 5257 5258 size_t symbols_processed() const { return (size_t)_symbols_processed; } 5259 size_t symbols_removed() const { return (size_t)_symbols_removed; } 5260 }; 5261 5262 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive, 5263 bool process_strings, bool process_symbols) { 5264 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ? 5265 _g1h->workers()->active_workers() : 1); 5266 5267 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols); 5268 if (G1CollectedHeap::use_parallel_gc_threads()) { 5269 set_par_threads(n_workers); 5270 workers()->run_task(&g1_unlink_task); 5271 set_par_threads(0); 5272 } else { 5273 g1_unlink_task.work(0); 5274 } 5275 if (G1TraceStringSymbolTableScrubbing) { 5276 gclog_or_tty->print_cr("Cleaned string and symbol table, " 5277 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, " 5278 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed", 5279 g1_unlink_task.strings_processed(), g1_unlink_task.strings_removed(), 5280 g1_unlink_task.symbols_processed(), g1_unlink_task.symbols_removed()); 5281 } 5282 5283 if (G1StringDedup::is_enabled()) { 5284 G1StringDedup::unlink(is_alive); 5285 } 5286 } 5287 5288 class RedirtyLoggedCardTableEntryFastClosure : public CardTableEntryClosure { 5289 public: 5290 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 5291 *card_ptr = CardTableModRefBS::dirty_card_val(); 5292 return true; 5293 } 5294 }; 5295 5296 void G1CollectedHeap::redirty_logged_cards() { 5297 guarantee(G1DeferredRSUpdate, "Must only be called when using deferred RS updates."); 5298 double redirty_logged_cards_start = os::elapsedTime(); 5299 5300 RedirtyLoggedCardTableEntryFastClosure redirty; 5301 dirty_card_queue_set().set_closure(&redirty); 5302 dirty_card_queue_set().apply_closure_to_all_completed_buffers(); 5303 5304 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set(); 5305 dcq.merge_bufferlists(&dirty_card_queue_set()); 5306 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed"); 5307 5308 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0); 5309 } 5310 5311 // Weak Reference Processing support 5312 5313 // An always "is_alive" closure that is used to preserve referents. 5314 // If the object is non-null then it's alive. Used in the preservation 5315 // of referent objects that are pointed to by reference objects 5316 // discovered by the CM ref processor. 5317 class G1AlwaysAliveClosure: public BoolObjectClosure { 5318 G1CollectedHeap* _g1; 5319 public: 5320 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 5321 bool do_object_b(oop p) { 5322 if (p != NULL) { 5323 return true; 5324 } 5325 return false; 5326 } 5327 }; 5328 5329 bool G1STWIsAliveClosure::do_object_b(oop p) { 5330 // An object is reachable if it is outside the collection set, 5331 // or is inside and copied. 5332 return !_g1->obj_in_cs(p) || p->is_forwarded(); 5333 } 5334 5335 // Non Copying Keep Alive closure 5336 class G1KeepAliveClosure: public OopClosure { 5337 G1CollectedHeap* _g1; 5338 public: 5339 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 5340 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } 5341 void do_oop( oop* p) { 5342 oop obj = *p; 5343 5344 if (_g1->obj_in_cs(obj)) { 5345 assert( obj->is_forwarded(), "invariant" ); 5346 *p = obj->forwardee(); 5347 } 5348 } 5349 }; 5350 5351 // Copying Keep Alive closure - can be called from both 5352 // serial and parallel code as long as different worker 5353 // threads utilize different G1ParScanThreadState instances 5354 // and different queues. 5355 5356 class G1CopyingKeepAliveClosure: public OopClosure { 5357 G1CollectedHeap* _g1h; 5358 OopClosure* _copy_non_heap_obj_cl; 5359 OopsInHeapRegionClosure* _copy_metadata_obj_cl; 5360 G1ParScanThreadState* _par_scan_state; 5361 5362 public: 5363 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, 5364 OopClosure* non_heap_obj_cl, 5365 OopsInHeapRegionClosure* metadata_obj_cl, 5366 G1ParScanThreadState* pss): 5367 _g1h(g1h), 5368 _copy_non_heap_obj_cl(non_heap_obj_cl), 5369 _copy_metadata_obj_cl(metadata_obj_cl), 5370 _par_scan_state(pss) 5371 {} 5372 5373 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 5374 virtual void do_oop( oop* p) { do_oop_work(p); } 5375 5376 template <class T> void do_oop_work(T* p) { 5377 oop obj = oopDesc::load_decode_heap_oop(p); 5378 5379 if (_g1h->obj_in_cs(obj)) { 5380 // If the referent object has been forwarded (either copied 5381 // to a new location or to itself in the event of an 5382 // evacuation failure) then we need to update the reference 5383 // field and, if both reference and referent are in the G1 5384 // heap, update the RSet for the referent. 5385 // 5386 // If the referent has not been forwarded then we have to keep 5387 // it alive by policy. Therefore we have copy the referent. 5388 // 5389 // If the reference field is in the G1 heap then we can push 5390 // on the PSS queue. When the queue is drained (after each 5391 // phase of reference processing) the object and it's followers 5392 // will be copied, the reference field set to point to the 5393 // new location, and the RSet updated. Otherwise we need to 5394 // use the the non-heap or metadata closures directly to copy 5395 // the referent object and update the pointer, while avoiding 5396 // updating the RSet. 5397 5398 if (_g1h->is_in_g1_reserved(p)) { 5399 _par_scan_state->push_on_queue(p); 5400 } else { 5401 assert(!Metaspace::contains((const void*)p), 5402 err_msg("Otherwise need to call _copy_metadata_obj_cl->do_oop(p) " 5403 PTR_FORMAT, p)); 5404 _copy_non_heap_obj_cl->do_oop(p); 5405 } 5406 } 5407 } 5408 }; 5409 5410 // Serial drain queue closure. Called as the 'complete_gc' 5411 // closure for each discovered list in some of the 5412 // reference processing phases. 5413 5414 class G1STWDrainQueueClosure: public VoidClosure { 5415 protected: 5416 G1CollectedHeap* _g1h; 5417 G1ParScanThreadState* _par_scan_state; 5418 5419 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 5420 5421 public: 5422 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : 5423 _g1h(g1h), 5424 _par_scan_state(pss) 5425 { } 5426 5427 void do_void() { 5428 G1ParScanThreadState* const pss = par_scan_state(); 5429 pss->trim_queue(); 5430 } 5431 }; 5432 5433 // Parallel Reference Processing closures 5434 5435 // Implementation of AbstractRefProcTaskExecutor for parallel reference 5436 // processing during G1 evacuation pauses. 5437 5438 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 5439 private: 5440 G1CollectedHeap* _g1h; 5441 RefToScanQueueSet* _queues; 5442 FlexibleWorkGang* _workers; 5443 int _active_workers; 5444 5445 public: 5446 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, 5447 FlexibleWorkGang* workers, 5448 RefToScanQueueSet *task_queues, 5449 int n_workers) : 5450 _g1h(g1h), 5451 _queues(task_queues), 5452 _workers(workers), 5453 _active_workers(n_workers) 5454 { 5455 assert(n_workers > 0, "shouldn't call this otherwise"); 5456 } 5457 5458 // Executes the given task using concurrent marking worker threads. 5459 virtual void execute(ProcessTask& task); 5460 virtual void execute(EnqueueTask& task); 5461 }; 5462 5463 // Gang task for possibly parallel reference processing 5464 5465 class G1STWRefProcTaskProxy: public AbstractGangTask { 5466 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 5467 ProcessTask& _proc_task; 5468 G1CollectedHeap* _g1h; 5469 RefToScanQueueSet *_task_queues; 5470 ParallelTaskTerminator* _terminator; 5471 5472 public: 5473 G1STWRefProcTaskProxy(ProcessTask& proc_task, 5474 G1CollectedHeap* g1h, 5475 RefToScanQueueSet *task_queues, 5476 ParallelTaskTerminator* terminator) : 5477 AbstractGangTask("Process reference objects in parallel"), 5478 _proc_task(proc_task), 5479 _g1h(g1h), 5480 _task_queues(task_queues), 5481 _terminator(terminator) 5482 {} 5483 5484 virtual void work(uint worker_id) { 5485 // The reference processing task executed by a single worker. 5486 ResourceMark rm; 5487 HandleMark hm; 5488 5489 G1STWIsAliveClosure is_alive(_g1h); 5490 5491 G1ParScanThreadState pss(_g1h, worker_id, NULL); 5492 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL); 5493 5494 pss.set_evac_failure_closure(&evac_failure_cl); 5495 5496 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL); 5497 G1ParScanMetadataClosure only_copy_metadata_cl(_g1h, &pss, NULL); 5498 5499 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL); 5500 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL); 5501 5502 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5503 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl; 5504 5505 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5506 // We also need to mark copied objects. 5507 copy_non_heap_cl = ©_mark_non_heap_cl; 5508 copy_metadata_cl = ©_mark_metadata_cl; 5509 } 5510 5511 // Keep alive closure. 5512 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss); 5513 5514 // Complete GC closure 5515 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator); 5516 5517 // Call the reference processing task's work routine. 5518 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); 5519 5520 // Note we cannot assert that the refs array is empty here as not all 5521 // of the processing tasks (specifically phase2 - pp2_work) execute 5522 // the complete_gc closure (which ordinarily would drain the queue) so 5523 // the queue may not be empty. 5524 } 5525 }; 5526 5527 // Driver routine for parallel reference processing. 5528 // Creates an instance of the ref processing gang 5529 // task and has the worker threads execute it. 5530 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) { 5531 assert(_workers != NULL, "Need parallel worker threads."); 5532 5533 ParallelTaskTerminator terminator(_active_workers, _queues); 5534 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator); 5535 5536 _g1h->set_par_threads(_active_workers); 5537 _workers->run_task(&proc_task_proxy); 5538 _g1h->set_par_threads(0); 5539 } 5540 5541 // Gang task for parallel reference enqueueing. 5542 5543 class G1STWRefEnqueueTaskProxy: public AbstractGangTask { 5544 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; 5545 EnqueueTask& _enq_task; 5546 5547 public: 5548 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) : 5549 AbstractGangTask("Enqueue reference objects in parallel"), 5550 _enq_task(enq_task) 5551 { } 5552 5553 virtual void work(uint worker_id) { 5554 _enq_task.work(worker_id); 5555 } 5556 }; 5557 5558 // Driver routine for parallel reference enqueueing. 5559 // Creates an instance of the ref enqueueing gang 5560 // task and has the worker threads execute it. 5561 5562 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) { 5563 assert(_workers != NULL, "Need parallel worker threads."); 5564 5565 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task); 5566 5567 _g1h->set_par_threads(_active_workers); 5568 _workers->run_task(&enq_task_proxy); 5569 _g1h->set_par_threads(0); 5570 } 5571 5572 // End of weak reference support closures 5573 5574 // Abstract task used to preserve (i.e. copy) any referent objects 5575 // that are in the collection set and are pointed to by reference 5576 // objects discovered by the CM ref processor. 5577 5578 class G1ParPreserveCMReferentsTask: public AbstractGangTask { 5579 protected: 5580 G1CollectedHeap* _g1h; 5581 RefToScanQueueSet *_queues; 5582 ParallelTaskTerminator _terminator; 5583 uint _n_workers; 5584 5585 public: 5586 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) : 5587 AbstractGangTask("ParPreserveCMReferents"), 5588 _g1h(g1h), 5589 _queues(task_queues), 5590 _terminator(workers, _queues), 5591 _n_workers(workers) 5592 { } 5593 5594 void work(uint worker_id) { 5595 ResourceMark rm; 5596 HandleMark hm; 5597 5598 G1ParScanThreadState pss(_g1h, worker_id, NULL); 5599 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL); 5600 5601 pss.set_evac_failure_closure(&evac_failure_cl); 5602 5603 assert(pss.refs()->is_empty(), "both queue and overflow should be empty"); 5604 5605 5606 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL); 5607 G1ParScanMetadataClosure only_copy_metadata_cl(_g1h, &pss, NULL); 5608 5609 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL); 5610 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL); 5611 5612 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5613 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl; 5614 5615 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5616 // We also need to mark copied objects. 5617 copy_non_heap_cl = ©_mark_non_heap_cl; 5618 copy_metadata_cl = ©_mark_metadata_cl; 5619 } 5620 5621 // Is alive closure 5622 G1AlwaysAliveClosure always_alive(_g1h); 5623 5624 // Copying keep alive closure. Applied to referent objects that need 5625 // to be copied. 5626 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss); 5627 5628 ReferenceProcessor* rp = _g1h->ref_processor_cm(); 5629 5630 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q(); 5631 uint stride = MIN2(MAX2(_n_workers, 1U), limit); 5632 5633 // limit is set using max_num_q() - which was set using ParallelGCThreads. 5634 // So this must be true - but assert just in case someone decides to 5635 // change the worker ids. 5636 assert(0 <= worker_id && worker_id < limit, "sanity"); 5637 assert(!rp->discovery_is_atomic(), "check this code"); 5638 5639 // Select discovered lists [i, i+stride, i+2*stride,...,limit) 5640 for (uint idx = worker_id; idx < limit; idx += stride) { 5641 DiscoveredList& ref_list = rp->discovered_refs()[idx]; 5642 5643 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive); 5644 while (iter.has_next()) { 5645 // Since discovery is not atomic for the CM ref processor, we 5646 // can see some null referent objects. 5647 iter.load_ptrs(DEBUG_ONLY(true)); 5648 oop ref = iter.obj(); 5649 5650 // This will filter nulls. 5651 if (iter.is_referent_alive()) { 5652 iter.make_referent_alive(); 5653 } 5654 iter.move_to_next(); 5655 } 5656 } 5657 5658 // Drain the queue - which may cause stealing 5659 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator); 5660 drain_queue.do_void(); 5661 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure 5662 assert(pss.refs()->is_empty(), "should be"); 5663 } 5664 }; 5665 5666 // Weak Reference processing during an evacuation pause (part 1). 5667 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) { 5668 double ref_proc_start = os::elapsedTime(); 5669 5670 ReferenceProcessor* rp = _ref_processor_stw; 5671 assert(rp->discovery_enabled(), "should have been enabled"); 5672 5673 // Any reference objects, in the collection set, that were 'discovered' 5674 // by the CM ref processor should have already been copied (either by 5675 // applying the external root copy closure to the discovered lists, or 5676 // by following an RSet entry). 5677 // 5678 // But some of the referents, that are in the collection set, that these 5679 // reference objects point to may not have been copied: the STW ref 5680 // processor would have seen that the reference object had already 5681 // been 'discovered' and would have skipped discovering the reference, 5682 // but would not have treated the reference object as a regular oop. 5683 // As a result the copy closure would not have been applied to the 5684 // referent object. 5685 // 5686 // We need to explicitly copy these referent objects - the references 5687 // will be processed at the end of remarking. 5688 // 5689 // We also need to do this copying before we process the reference 5690 // objects discovered by the STW ref processor in case one of these 5691 // referents points to another object which is also referenced by an 5692 // object discovered by the STW ref processor. 5693 5694 assert(!G1CollectedHeap::use_parallel_gc_threads() || 5695 no_of_gc_workers == workers()->active_workers(), 5696 "Need to reset active GC workers"); 5697 5698 set_par_threads(no_of_gc_workers); 5699 G1ParPreserveCMReferentsTask keep_cm_referents(this, 5700 no_of_gc_workers, 5701 _task_queues); 5702 5703 if (G1CollectedHeap::use_parallel_gc_threads()) { 5704 workers()->run_task(&keep_cm_referents); 5705 } else { 5706 keep_cm_referents.work(0); 5707 } 5708 5709 set_par_threads(0); 5710 5711 // Closure to test whether a referent is alive. 5712 G1STWIsAliveClosure is_alive(this); 5713 5714 // Even when parallel reference processing is enabled, the processing 5715 // of JNI refs is serial and performed serially by the current thread 5716 // rather than by a worker. The following PSS will be used for processing 5717 // JNI refs. 5718 5719 // Use only a single queue for this PSS. 5720 G1ParScanThreadState pss(this, 0, NULL); 5721 5722 // We do not embed a reference processor in the copying/scanning 5723 // closures while we're actually processing the discovered 5724 // reference objects. 5725 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL); 5726 5727 pss.set_evac_failure_closure(&evac_failure_cl); 5728 5729 assert(pss.refs()->is_empty(), "pre-condition"); 5730 5731 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL); 5732 G1ParScanMetadataClosure only_copy_metadata_cl(this, &pss, NULL); 5733 5734 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL); 5735 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(this, &pss, NULL); 5736 5737 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5738 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl; 5739 5740 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5741 // We also need to mark copied objects. 5742 copy_non_heap_cl = ©_mark_non_heap_cl; 5743 copy_metadata_cl = ©_mark_metadata_cl; 5744 } 5745 5746 // Keep alive closure. 5747 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, copy_metadata_cl, &pss); 5748 5749 // Serial Complete GC closure 5750 G1STWDrainQueueClosure drain_queue(this, &pss); 5751 5752 // Setup the soft refs policy... 5753 rp->setup_policy(false); 5754 5755 ReferenceProcessorStats stats; 5756 if (!rp->processing_is_mt()) { 5757 // Serial reference processing... 5758 stats = rp->process_discovered_references(&is_alive, 5759 &keep_alive, 5760 &drain_queue, 5761 NULL, 5762 _gc_timer_stw, 5763 _gc_tracer_stw->gc_id()); 5764 } else { 5765 // Parallel reference processing 5766 assert(rp->num_q() == no_of_gc_workers, "sanity"); 5767 assert(no_of_gc_workers <= rp->max_num_q(), "sanity"); 5768 5769 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers); 5770 stats = rp->process_discovered_references(&is_alive, 5771 &keep_alive, 5772 &drain_queue, 5773 &par_task_executor, 5774 _gc_timer_stw, 5775 _gc_tracer_stw->gc_id()); 5776 } 5777 5778 _gc_tracer_stw->report_gc_reference_stats(stats); 5779 // We have completed copying any necessary live referent objects 5780 // (that were not copied during the actual pause) so we can 5781 // retire any active alloc buffers 5782 pss.retire_alloc_buffers(); 5783 assert(pss.refs()->is_empty(), "both queue and overflow should be empty"); 5784 5785 double ref_proc_time = os::elapsedTime() - ref_proc_start; 5786 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 5787 } 5788 5789 // Weak Reference processing during an evacuation pause (part 2). 5790 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) { 5791 double ref_enq_start = os::elapsedTime(); 5792 5793 ReferenceProcessor* rp = _ref_processor_stw; 5794 assert(!rp->discovery_enabled(), "should have been disabled as part of processing"); 5795 5796 // Now enqueue any remaining on the discovered lists on to 5797 // the pending list. 5798 if (!rp->processing_is_mt()) { 5799 // Serial reference processing... 5800 rp->enqueue_discovered_references(); 5801 } else { 5802 // Parallel reference enqueueing 5803 5804 assert(no_of_gc_workers == workers()->active_workers(), 5805 "Need to reset active workers"); 5806 assert(rp->num_q() == no_of_gc_workers, "sanity"); 5807 assert(no_of_gc_workers <= rp->max_num_q(), "sanity"); 5808 5809 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers); 5810 rp->enqueue_discovered_references(&par_task_executor); 5811 } 5812 5813 rp->verify_no_references_recorded(); 5814 assert(!rp->discovery_enabled(), "should have been disabled"); 5815 5816 // FIXME 5817 // CM's reference processing also cleans up the string and symbol tables. 5818 // Should we do that here also? We could, but it is a serial operation 5819 // and could significantly increase the pause time. 5820 5821 double ref_enq_time = os::elapsedTime() - ref_enq_start; 5822 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0); 5823 } 5824 5825 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) { 5826 _expand_heap_after_alloc_failure = true; 5827 _evacuation_failed = false; 5828 5829 // Should G1EvacuationFailureALot be in effect for this GC? 5830 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) 5831 5832 g1_rem_set()->prepare_for_oops_into_collection_set_do(); 5833 5834 // Disable the hot card cache. 5835 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 5836 hot_card_cache->reset_hot_cache_claimed_index(); 5837 hot_card_cache->set_use_cache(false); 5838 5839 uint n_workers; 5840 if (G1CollectedHeap::use_parallel_gc_threads()) { 5841 n_workers = 5842 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 5843 workers()->active_workers(), 5844 Threads::number_of_non_daemon_threads()); 5845 assert(UseDynamicNumberOfGCThreads || 5846 n_workers == workers()->total_workers(), 5847 "If not dynamic should be using all the workers"); 5848 workers()->set_active_workers(n_workers); 5849 set_par_threads(n_workers); 5850 } else { 5851 assert(n_par_threads() == 0, 5852 "Should be the original non-parallel value"); 5853 n_workers = 1; 5854 } 5855 5856 G1ParTask g1_par_task(this, _task_queues); 5857 5858 init_for_evac_failure(NULL); 5859 5860 rem_set()->prepare_for_younger_refs_iterate(true); 5861 5862 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty"); 5863 double start_par_time_sec = os::elapsedTime(); 5864 double end_par_time_sec; 5865 5866 { 5867 StrongRootsScope srs(this); 5868 5869 if (G1CollectedHeap::use_parallel_gc_threads()) { 5870 // The individual threads will set their evac-failure closures. 5871 if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr(); 5872 // These tasks use ShareHeap::_process_strong_tasks 5873 assert(UseDynamicNumberOfGCThreads || 5874 workers()->active_workers() == workers()->total_workers(), 5875 "If not dynamic should be using all the workers"); 5876 workers()->run_task(&g1_par_task); 5877 } else { 5878 g1_par_task.set_for_termination(n_workers); 5879 g1_par_task.work(0); 5880 } 5881 end_par_time_sec = os::elapsedTime(); 5882 5883 // Closing the inner scope will execute the destructor 5884 // for the StrongRootsScope object. We record the current 5885 // elapsed time before closing the scope so that time 5886 // taken for the SRS destructor is NOT included in the 5887 // reported parallel time. 5888 } 5889 5890 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0; 5891 g1_policy()->phase_times()->record_par_time(par_time_ms); 5892 5893 double code_root_fixup_time_ms = 5894 (os::elapsedTime() - end_par_time_sec) * 1000.0; 5895 g1_policy()->phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms); 5896 5897 set_par_threads(0); 5898 5899 // Process any discovered reference objects - we have 5900 // to do this _before_ we retire the GC alloc regions 5901 // as we may have to copy some 'reachable' referent 5902 // objects (and their reachable sub-graphs) that were 5903 // not copied during the pause. 5904 process_discovered_references(n_workers); 5905 5906 // Weak root processing. 5907 { 5908 G1STWIsAliveClosure is_alive(this); 5909 G1KeepAliveClosure keep_alive(this); 5910 JNIHandles::weak_oops_do(&is_alive, &keep_alive); 5911 if (G1StringDedup::is_enabled()) { 5912 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive); 5913 } 5914 } 5915 5916 release_gc_alloc_regions(n_workers, evacuation_info); 5917 g1_rem_set()->cleanup_after_oops_into_collection_set_do(); 5918 5919 // Reset and re-enable the hot card cache. 5920 // Note the counts for the cards in the regions in the 5921 // collection set are reset when the collection set is freed. 5922 hot_card_cache->reset_hot_cache(); 5923 hot_card_cache->set_use_cache(true); 5924 5925 // Migrate the strong code roots attached to each region in 5926 // the collection set. Ideally we would like to do this 5927 // after we have finished the scanning/evacuation of the 5928 // strong code roots for a particular heap region. 5929 migrate_strong_code_roots(); 5930 5931 purge_code_root_memory(); 5932 5933 if (g1_policy()->during_initial_mark_pause()) { 5934 // Reset the claim values set during marking the strong code roots 5935 reset_heap_region_claim_values(); 5936 } 5937 5938 finalize_for_evac_failure(); 5939 5940 if (evacuation_failed()) { 5941 remove_self_forwarding_pointers(); 5942 5943 // Reset the G1EvacuationFailureALot counters and flags 5944 // Note: the values are reset only when an actual 5945 // evacuation failure occurs. 5946 NOT_PRODUCT(reset_evacuation_should_fail();) 5947 } 5948 5949 // Enqueue any remaining references remaining on the STW 5950 // reference processor's discovered lists. We need to do 5951 // this after the card table is cleaned (and verified) as 5952 // the act of enqueueing entries on to the pending list 5953 // will log these updates (and dirty their associated 5954 // cards). We need these updates logged to update any 5955 // RSets. 5956 enqueue_discovered_references(n_workers); 5957 5958 if (G1DeferredRSUpdate) { 5959 redirty_logged_cards(); 5960 } 5961 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 5962 } 5963 5964 void G1CollectedHeap::free_region(HeapRegion* hr, 5965 FreeRegionList* free_list, 5966 bool par, 5967 bool locked) { 5968 assert(!hr->isHumongous(), "this is only for non-humongous regions"); 5969 assert(!hr->is_empty(), "the region should not be empty"); 5970 assert(free_list != NULL, "pre-condition"); 5971 5972 // Clear the card counts for this region. 5973 // Note: we only need to do this if the region is not young 5974 // (since we don't refine cards in young regions). 5975 if (!hr->is_young()) { 5976 _cg1r->hot_card_cache()->reset_card_counts(hr); 5977 } 5978 hr->hr_clear(par, true /* clear_space */, locked /* locked */); 5979 free_list->add_ordered(hr); 5980 } 5981 5982 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 5983 FreeRegionList* free_list, 5984 bool par) { 5985 assert(hr->startsHumongous(), "this is only for starts humongous regions"); 5986 assert(free_list != NULL, "pre-condition"); 5987 5988 size_t hr_capacity = hr->capacity(); 5989 // We need to read this before we make the region non-humongous, 5990 // otherwise the information will be gone. 5991 uint last_index = hr->last_hc_index(); 5992 hr->set_notHumongous(); 5993 free_region(hr, free_list, par); 5994 5995 uint i = hr->hrs_index() + 1; 5996 while (i < last_index) { 5997 HeapRegion* curr_hr = region_at(i); 5998 assert(curr_hr->continuesHumongous(), "invariant"); 5999 curr_hr->set_notHumongous(); 6000 free_region(curr_hr, free_list, par); 6001 i += 1; 6002 } 6003 } 6004 6005 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed, 6006 const HeapRegionSetCount& humongous_regions_removed) { 6007 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) { 6008 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 6009 _old_set.bulk_remove(old_regions_removed); 6010 _humongous_set.bulk_remove(humongous_regions_removed); 6011 } 6012 6013 } 6014 6015 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) { 6016 assert(list != NULL, "list can't be null"); 6017 if (!list->is_empty()) { 6018 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag); 6019 _free_list.add_ordered(list); 6020 } 6021 } 6022 6023 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) { 6024 assert(_summary_bytes_used >= bytes, 6025 err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" should be >= bytes: "SIZE_FORMAT, 6026 _summary_bytes_used, bytes)); 6027 _summary_bytes_used -= bytes; 6028 } 6029 6030 class G1ParCleanupCTTask : public AbstractGangTask { 6031 G1SATBCardTableModRefBS* _ct_bs; 6032 G1CollectedHeap* _g1h; 6033 HeapRegion* volatile _su_head; 6034 public: 6035 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs, 6036 G1CollectedHeap* g1h) : 6037 AbstractGangTask("G1 Par Cleanup CT Task"), 6038 _ct_bs(ct_bs), _g1h(g1h) { } 6039 6040 void work(uint worker_id) { 6041 HeapRegion* r; 6042 while (r = _g1h->pop_dirty_cards_region()) { 6043 clear_cards(r); 6044 } 6045 } 6046 6047 void clear_cards(HeapRegion* r) { 6048 // Cards of the survivors should have already been dirtied. 6049 if (!r->is_survivor()) { 6050 _ct_bs->clear(MemRegion(r->bottom(), r->end())); 6051 } 6052 } 6053 }; 6054 6055 #ifndef PRODUCT 6056 class G1VerifyCardTableCleanup: public HeapRegionClosure { 6057 G1CollectedHeap* _g1h; 6058 G1SATBCardTableModRefBS* _ct_bs; 6059 public: 6060 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs) 6061 : _g1h(g1h), _ct_bs(ct_bs) { } 6062 virtual bool doHeapRegion(HeapRegion* r) { 6063 if (r->is_survivor()) { 6064 _g1h->verify_dirty_region(r); 6065 } else { 6066 _g1h->verify_not_dirty_region(r); 6067 } 6068 return false; 6069 } 6070 }; 6071 6072 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) { 6073 // All of the region should be clean. 6074 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 6075 MemRegion mr(hr->bottom(), hr->end()); 6076 ct_bs->verify_not_dirty_region(mr); 6077 } 6078 6079 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) { 6080 // We cannot guarantee that [bottom(),end()] is dirty. Threads 6081 // dirty allocated blocks as they allocate them. The thread that 6082 // retires each region and replaces it with a new one will do a 6083 // maximal allocation to fill in [pre_dummy_top(),end()] but will 6084 // not dirty that area (one less thing to have to do while holding 6085 // a lock). So we can only verify that [bottom(),pre_dummy_top()] 6086 // is dirty. 6087 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 6088 MemRegion mr(hr->bottom(), hr->pre_dummy_top()); 6089 if (hr->is_young()) { 6090 ct_bs->verify_g1_young_region(mr); 6091 } else { 6092 ct_bs->verify_dirty_region(mr); 6093 } 6094 } 6095 6096 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) { 6097 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 6098 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) { 6099 verify_dirty_region(hr); 6100 } 6101 } 6102 6103 void G1CollectedHeap::verify_dirty_young_regions() { 6104 verify_dirty_young_list(_young_list->first_region()); 6105 } 6106 #endif 6107 6108 void G1CollectedHeap::cleanUpCardTable() { 6109 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 6110 double start = os::elapsedTime(); 6111 6112 { 6113 // Iterate over the dirty cards region list. 6114 G1ParCleanupCTTask cleanup_task(ct_bs, this); 6115 6116 if (G1CollectedHeap::use_parallel_gc_threads()) { 6117 set_par_threads(); 6118 workers()->run_task(&cleanup_task); 6119 set_par_threads(0); 6120 } else { 6121 while (_dirty_cards_region_list) { 6122 HeapRegion* r = _dirty_cards_region_list; 6123 cleanup_task.clear_cards(r); 6124 _dirty_cards_region_list = r->get_next_dirty_cards_region(); 6125 if (_dirty_cards_region_list == r) { 6126 // The last region. 6127 _dirty_cards_region_list = NULL; 6128 } 6129 r->set_next_dirty_cards_region(NULL); 6130 } 6131 } 6132 #ifndef PRODUCT 6133 if (G1VerifyCTCleanup || VerifyAfterGC) { 6134 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs); 6135 heap_region_iterate(&cleanup_verifier); 6136 } 6137 #endif 6138 } 6139 6140 double elapsed = os::elapsedTime() - start; 6141 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0); 6142 } 6143 6144 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) { 6145 size_t pre_used = 0; 6146 FreeRegionList local_free_list("Local List for CSet Freeing"); 6147 6148 double young_time_ms = 0.0; 6149 double non_young_time_ms = 0.0; 6150 6151 // Since the collection set is a superset of the the young list, 6152 // all we need to do to clear the young list is clear its 6153 // head and length, and unlink any young regions in the code below 6154 _young_list->clear(); 6155 6156 G1CollectorPolicy* policy = g1_policy(); 6157 6158 double start_sec = os::elapsedTime(); 6159 bool non_young = true; 6160 6161 HeapRegion* cur = cs_head; 6162 int age_bound = -1; 6163 size_t rs_lengths = 0; 6164 6165 while (cur != NULL) { 6166 assert(!is_on_master_free_list(cur), "sanity"); 6167 if (non_young) { 6168 if (cur->is_young()) { 6169 double end_sec = os::elapsedTime(); 6170 double elapsed_ms = (end_sec - start_sec) * 1000.0; 6171 non_young_time_ms += elapsed_ms; 6172 6173 start_sec = os::elapsedTime(); 6174 non_young = false; 6175 } 6176 } else { 6177 if (!cur->is_young()) { 6178 double end_sec = os::elapsedTime(); 6179 double elapsed_ms = (end_sec - start_sec) * 1000.0; 6180 young_time_ms += elapsed_ms; 6181 6182 start_sec = os::elapsedTime(); 6183 non_young = true; 6184 } 6185 } 6186 6187 rs_lengths += cur->rem_set()->occupied_locked(); 6188 6189 HeapRegion* next = cur->next_in_collection_set(); 6190 assert(cur->in_collection_set(), "bad CS"); 6191 cur->set_next_in_collection_set(NULL); 6192 cur->set_in_collection_set(false); 6193 6194 if (cur->is_young()) { 6195 int index = cur->young_index_in_cset(); 6196 assert(index != -1, "invariant"); 6197 assert((uint) index < policy->young_cset_region_length(), "invariant"); 6198 size_t words_survived = _surviving_young_words[index]; 6199 cur->record_surv_words_in_group(words_survived); 6200 6201 // At this point the we have 'popped' cur from the collection set 6202 // (linked via next_in_collection_set()) but it is still in the 6203 // young list (linked via next_young_region()). Clear the 6204 // _next_young_region field. 6205 cur->set_next_young_region(NULL); 6206 } else { 6207 int index = cur->young_index_in_cset(); 6208 assert(index == -1, "invariant"); 6209 } 6210 6211 assert( (cur->is_young() && cur->young_index_in_cset() > -1) || 6212 (!cur->is_young() && cur->young_index_in_cset() == -1), 6213 "invariant" ); 6214 6215 if (!cur->evacuation_failed()) { 6216 MemRegion used_mr = cur->used_region(); 6217 6218 // And the region is empty. 6219 assert(!used_mr.is_empty(), "Should not have empty regions in a CS."); 6220 pre_used += cur->used(); 6221 free_region(cur, &local_free_list, false /* par */, true /* locked */); 6222 } else { 6223 cur->uninstall_surv_rate_group(); 6224 if (cur->is_young()) { 6225 cur->set_young_index_in_cset(-1); 6226 } 6227 cur->set_not_young(); 6228 cur->set_evacuation_failed(false); 6229 // The region is now considered to be old. 6230 _old_set.add(cur); 6231 evacuation_info.increment_collectionset_used_after(cur->used()); 6232 } 6233 cur = next; 6234 } 6235 6236 evacuation_info.set_regions_freed(local_free_list.length()); 6237 policy->record_max_rs_lengths(rs_lengths); 6238 policy->cset_regions_freed(); 6239 6240 double end_sec = os::elapsedTime(); 6241 double elapsed_ms = (end_sec - start_sec) * 1000.0; 6242 6243 if (non_young) { 6244 non_young_time_ms += elapsed_ms; 6245 } else { 6246 young_time_ms += elapsed_ms; 6247 } 6248 6249 prepend_to_freelist(&local_free_list); 6250 decrement_summary_bytes(pre_used); 6251 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms); 6252 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms); 6253 } 6254 6255 // This routine is similar to the above but does not record 6256 // any policy statistics or update free lists; we are abandoning 6257 // the current incremental collection set in preparation of a 6258 // full collection. After the full GC we will start to build up 6259 // the incremental collection set again. 6260 // This is only called when we're doing a full collection 6261 // and is immediately followed by the tearing down of the young list. 6262 6263 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) { 6264 HeapRegion* cur = cs_head; 6265 6266 while (cur != NULL) { 6267 HeapRegion* next = cur->next_in_collection_set(); 6268 assert(cur->in_collection_set(), "bad CS"); 6269 cur->set_next_in_collection_set(NULL); 6270 cur->set_in_collection_set(false); 6271 cur->set_young_index_in_cset(-1); 6272 cur = next; 6273 } 6274 } 6275 6276 void G1CollectedHeap::set_free_regions_coming() { 6277 if (G1ConcRegionFreeingVerbose) { 6278 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " 6279 "setting free regions coming"); 6280 } 6281 6282 assert(!free_regions_coming(), "pre-condition"); 6283 _free_regions_coming = true; 6284 } 6285 6286 void G1CollectedHeap::reset_free_regions_coming() { 6287 assert(free_regions_coming(), "pre-condition"); 6288 6289 { 6290 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6291 _free_regions_coming = false; 6292 SecondaryFreeList_lock->notify_all(); 6293 } 6294 6295 if (G1ConcRegionFreeingVerbose) { 6296 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " 6297 "reset free regions coming"); 6298 } 6299 } 6300 6301 void G1CollectedHeap::wait_while_free_regions_coming() { 6302 // Most of the time we won't have to wait, so let's do a quick test 6303 // first before we take the lock. 6304 if (!free_regions_coming()) { 6305 return; 6306 } 6307 6308 if (G1ConcRegionFreeingVerbose) { 6309 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " 6310 "waiting for free regions"); 6311 } 6312 6313 { 6314 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6315 while (free_regions_coming()) { 6316 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 6317 } 6318 } 6319 6320 if (G1ConcRegionFreeingVerbose) { 6321 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " 6322 "done waiting for free regions"); 6323 } 6324 } 6325 6326 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 6327 assert(heap_lock_held_for_gc(), 6328 "the heap lock should already be held by or for this thread"); 6329 _young_list->push_region(hr); 6330 } 6331 6332 class NoYoungRegionsClosure: public HeapRegionClosure { 6333 private: 6334 bool _success; 6335 public: 6336 NoYoungRegionsClosure() : _success(true) { } 6337 bool doHeapRegion(HeapRegion* r) { 6338 if (r->is_young()) { 6339 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young", 6340 r->bottom(), r->end()); 6341 _success = false; 6342 } 6343 return false; 6344 } 6345 bool success() { return _success; } 6346 }; 6347 6348 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) { 6349 bool ret = _young_list->check_list_empty(check_sample); 6350 6351 if (check_heap) { 6352 NoYoungRegionsClosure closure; 6353 heap_region_iterate(&closure); 6354 ret = ret && closure.success(); 6355 } 6356 6357 return ret; 6358 } 6359 6360 class TearDownRegionSetsClosure : public HeapRegionClosure { 6361 private: 6362 HeapRegionSet *_old_set; 6363 6364 public: 6365 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { } 6366 6367 bool doHeapRegion(HeapRegion* r) { 6368 if (r->is_empty()) { 6369 // We ignore empty regions, we'll empty the free list afterwards 6370 } else if (r->is_young()) { 6371 // We ignore young regions, we'll empty the young list afterwards 6372 } else if (r->isHumongous()) { 6373 // We ignore humongous regions, we're not tearing down the 6374 // humongous region set 6375 } else { 6376 // The rest should be old 6377 _old_set->remove(r); 6378 } 6379 return false; 6380 } 6381 6382 ~TearDownRegionSetsClosure() { 6383 assert(_old_set->is_empty(), "post-condition"); 6384 } 6385 }; 6386 6387 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) { 6388 assert_at_safepoint(true /* should_be_vm_thread */); 6389 6390 if (!free_list_only) { 6391 TearDownRegionSetsClosure cl(&_old_set); 6392 heap_region_iterate(&cl); 6393 6394 // Note that emptying the _young_list is postponed and instead done as 6395 // the first step when rebuilding the regions sets again. The reason for 6396 // this is that during a full GC string deduplication needs to know if 6397 // a collected region was young or old when the full GC was initiated. 6398 } 6399 _free_list.remove_all(); 6400 } 6401 6402 class RebuildRegionSetsClosure : public HeapRegionClosure { 6403 private: 6404 bool _free_list_only; 6405 HeapRegionSet* _old_set; 6406 FreeRegionList* _free_list; 6407 size_t _total_used; 6408 6409 public: 6410 RebuildRegionSetsClosure(bool free_list_only, 6411 HeapRegionSet* old_set, FreeRegionList* free_list) : 6412 _free_list_only(free_list_only), 6413 _old_set(old_set), _free_list(free_list), _total_used(0) { 6414 assert(_free_list->is_empty(), "pre-condition"); 6415 if (!free_list_only) { 6416 assert(_old_set->is_empty(), "pre-condition"); 6417 } 6418 } 6419 6420 bool doHeapRegion(HeapRegion* r) { 6421 if (r->continuesHumongous()) { 6422 return false; 6423 } 6424 6425 if (r->is_empty()) { 6426 // Add free regions to the free list 6427 _free_list->add_as_tail(r); 6428 } else if (!_free_list_only) { 6429 assert(!r->is_young(), "we should not come across young regions"); 6430 6431 if (r->isHumongous()) { 6432 // We ignore humongous regions, we left the humongous set unchanged 6433 } else { 6434 // The rest should be old, add them to the old set 6435 _old_set->add(r); 6436 } 6437 _total_used += r->used(); 6438 } 6439 6440 return false; 6441 } 6442 6443 size_t total_used() { 6444 return _total_used; 6445 } 6446 }; 6447 6448 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { 6449 assert_at_safepoint(true /* should_be_vm_thread */); 6450 6451 if (!free_list_only) { 6452 _young_list->empty_list(); 6453 } 6454 6455 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_free_list); 6456 heap_region_iterate(&cl); 6457 6458 if (!free_list_only) { 6459 _summary_bytes_used = cl.total_used(); 6460 } 6461 assert(_summary_bytes_used == recalculate_used(), 6462 err_msg("inconsistent _summary_bytes_used, " 6463 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT, 6464 _summary_bytes_used, recalculate_used())); 6465 } 6466 6467 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) { 6468 _refine_cte_cl->set_concurrent(concurrent); 6469 } 6470 6471 bool G1CollectedHeap::is_in_closed_subset(const void* p) const { 6472 HeapRegion* hr = heap_region_containing(p); 6473 if (hr == NULL) { 6474 return false; 6475 } else { 6476 return hr->is_in(p); 6477 } 6478 } 6479 6480 // Methods for the mutator alloc region 6481 6482 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 6483 bool force) { 6484 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6485 assert(!force || g1_policy()->can_expand_young_list(), 6486 "if force is true we should be able to expand the young list"); 6487 bool young_list_full = g1_policy()->is_young_list_full(); 6488 if (force || !young_list_full) { 6489 HeapRegion* new_alloc_region = new_region(word_size, 6490 false /* is_old */, 6491 false /* do_expand */); 6492 if (new_alloc_region != NULL) { 6493 set_region_short_lived_locked(new_alloc_region); 6494 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full); 6495 return new_alloc_region; 6496 } 6497 } 6498 return NULL; 6499 } 6500 6501 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 6502 size_t allocated_bytes) { 6503 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6504 assert(alloc_region->is_young(), "all mutator alloc regions should be young"); 6505 6506 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region); 6507 _summary_bytes_used += allocated_bytes; 6508 _hr_printer.retire(alloc_region); 6509 // We update the eden sizes here, when the region is retired, 6510 // instead of when it's allocated, since this is the point that its 6511 // used space has been recored in _summary_bytes_used. 6512 g1mm()->update_eden_size(); 6513 } 6514 6515 HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size, 6516 bool force) { 6517 return _g1h->new_mutator_alloc_region(word_size, force); 6518 } 6519 6520 void G1CollectedHeap::set_par_threads() { 6521 // Don't change the number of workers. Use the value previously set 6522 // in the workgroup. 6523 assert(G1CollectedHeap::use_parallel_gc_threads(), "shouldn't be here otherwise"); 6524 uint n_workers = workers()->active_workers(); 6525 assert(UseDynamicNumberOfGCThreads || 6526 n_workers == workers()->total_workers(), 6527 "Otherwise should be using the total number of workers"); 6528 if (n_workers == 0) { 6529 assert(false, "Should have been set in prior evacuation pause."); 6530 n_workers = ParallelGCThreads; 6531 workers()->set_active_workers(n_workers); 6532 } 6533 set_par_threads(n_workers); 6534 } 6535 6536 void MutatorAllocRegion::retire_region(HeapRegion* alloc_region, 6537 size_t allocated_bytes) { 6538 _g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes); 6539 } 6540 6541 // Methods for the GC alloc regions 6542 6543 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, 6544 uint count, 6545 GCAllocPurpose ap) { 6546 assert(FreeList_lock->owned_by_self(), "pre-condition"); 6547 6548 if (count < g1_policy()->max_regions(ap)) { 6549 bool survivor = (ap == GCAllocForSurvived); 6550 HeapRegion* new_alloc_region = new_region(word_size, 6551 !survivor, 6552 true /* do_expand */); 6553 if (new_alloc_region != NULL) { 6554 // We really only need to do this for old regions given that we 6555 // should never scan survivors. But it doesn't hurt to do it 6556 // for survivors too. 6557 new_alloc_region->set_saved_mark(); 6558 if (survivor) { 6559 new_alloc_region->set_survivor(); 6560 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor); 6561 } else { 6562 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old); 6563 } 6564 bool during_im = g1_policy()->during_initial_mark_pause(); 6565 new_alloc_region->note_start_of_copying(during_im); 6566 return new_alloc_region; 6567 } else { 6568 g1_policy()->note_alloc_region_limit_reached(ap); 6569 } 6570 } 6571 return NULL; 6572 } 6573 6574 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 6575 size_t allocated_bytes, 6576 GCAllocPurpose ap) { 6577 bool during_im = g1_policy()->during_initial_mark_pause(); 6578 alloc_region->note_end_of_copying(during_im); 6579 g1_policy()->record_bytes_copied_during_gc(allocated_bytes); 6580 if (ap == GCAllocForSurvived) { 6581 young_list()->add_survivor_region(alloc_region); 6582 } else { 6583 _old_set.add(alloc_region); 6584 } 6585 _hr_printer.retire(alloc_region); 6586 } 6587 6588 HeapRegion* SurvivorGCAllocRegion::allocate_new_region(size_t word_size, 6589 bool force) { 6590 assert(!force, "not supported for GC alloc regions"); 6591 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForSurvived); 6592 } 6593 6594 void SurvivorGCAllocRegion::retire_region(HeapRegion* alloc_region, 6595 size_t allocated_bytes) { 6596 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes, 6597 GCAllocForSurvived); 6598 } 6599 6600 HeapRegion* OldGCAllocRegion::allocate_new_region(size_t word_size, 6601 bool force) { 6602 assert(!force, "not supported for GC alloc regions"); 6603 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForTenured); 6604 } 6605 6606 void OldGCAllocRegion::retire_region(HeapRegion* alloc_region, 6607 size_t allocated_bytes) { 6608 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes, 6609 GCAllocForTenured); 6610 } 6611 // Heap region set verification 6612 6613 class VerifyRegionListsClosure : public HeapRegionClosure { 6614 private: 6615 HeapRegionSet* _old_set; 6616 HeapRegionSet* _humongous_set; 6617 FreeRegionList* _free_list; 6618 6619 public: 6620 HeapRegionSetCount _old_count; 6621 HeapRegionSetCount _humongous_count; 6622 HeapRegionSetCount _free_count; 6623 6624 VerifyRegionListsClosure(HeapRegionSet* old_set, 6625 HeapRegionSet* humongous_set, 6626 FreeRegionList* free_list) : 6627 _old_set(old_set), _humongous_set(humongous_set), _free_list(free_list), 6628 _old_count(), _humongous_count(), _free_count(){ } 6629 6630 bool doHeapRegion(HeapRegion* hr) { 6631 if (hr->continuesHumongous()) { 6632 return false; 6633 } 6634 6635 if (hr->is_young()) { 6636 // TODO 6637 } else if (hr->startsHumongous()) { 6638 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->region_num())); 6639 _humongous_count.increment(1u, hr->capacity()); 6640 } else if (hr->is_empty()) { 6641 assert(hr->containing_set() == _free_list, err_msg("Heap region %u is empty but not on the free list.", hr->region_num())); 6642 _free_count.increment(1u, hr->capacity()); 6643 } else { 6644 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->region_num())); 6645 _old_count.increment(1u, hr->capacity()); 6646 } 6647 return false; 6648 } 6649 6650 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, FreeRegionList* free_list) { 6651 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length())); 6652 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6653 old_set->total_capacity_bytes(), _old_count.capacity())); 6654 6655 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length())); 6656 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6657 humongous_set->total_capacity_bytes(), _humongous_count.capacity())); 6658 6659 guarantee(free_list->length() == _free_count.length(), err_msg("Free list count mismatch. Expected %u, actual %u.", free_list->length(), _free_count.length())); 6660 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6661 free_list->total_capacity_bytes(), _free_count.capacity())); 6662 } 6663 }; 6664 6665 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index, 6666 HeapWord* bottom) { 6667 HeapWord* end = bottom + HeapRegion::GrainWords; 6668 MemRegion mr(bottom, end); 6669 assert(_g1_reserved.contains(mr), "invariant"); 6670 // This might return NULL if the allocation fails 6671 return new HeapRegion(hrs_index, _bot_shared, mr); 6672 } 6673 6674 void G1CollectedHeap::verify_region_sets() { 6675 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6676 6677 // First, check the explicit lists. 6678 _free_list.verify_list(); 6679 { 6680 // Given that a concurrent operation might be adding regions to 6681 // the secondary free list we have to take the lock before 6682 // verifying it. 6683 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6684 _secondary_free_list.verify_list(); 6685 } 6686 6687 // If a concurrent region freeing operation is in progress it will 6688 // be difficult to correctly attributed any free regions we come 6689 // across to the correct free list given that they might belong to 6690 // one of several (free_list, secondary_free_list, any local lists, 6691 // etc.). So, if that's the case we will skip the rest of the 6692 // verification operation. Alternatively, waiting for the concurrent 6693 // operation to complete will have a non-trivial effect on the GC's 6694 // operation (no concurrent operation will last longer than the 6695 // interval between two calls to verification) and it might hide 6696 // any issues that we would like to catch during testing. 6697 if (free_regions_coming()) { 6698 return; 6699 } 6700 6701 // Make sure we append the secondary_free_list on the free_list so 6702 // that all free regions we will come across can be safely 6703 // attributed to the free_list. 6704 append_secondary_free_list_if_not_empty_with_lock(); 6705 6706 // Finally, make sure that the region accounting in the lists is 6707 // consistent with what we see in the heap. 6708 6709 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_free_list); 6710 heap_region_iterate(&cl); 6711 cl.verify_counts(&_old_set, &_humongous_set, &_free_list); 6712 } 6713 6714 // Optimized nmethod scanning 6715 6716 class RegisterNMethodOopClosure: public OopClosure { 6717 G1CollectedHeap* _g1h; 6718 nmethod* _nm; 6719 6720 template <class T> void do_oop_work(T* p) { 6721 T heap_oop = oopDesc::load_heap_oop(p); 6722 if (!oopDesc::is_null(heap_oop)) { 6723 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 6724 HeapRegion* hr = _g1h->heap_region_containing(obj); 6725 assert(!hr->continuesHumongous(), 6726 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT 6727 " starting at "HR_FORMAT, 6728 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()))); 6729 6730 // HeapRegion::add_strong_code_root() avoids adding duplicate 6731 // entries but having duplicates is OK since we "mark" nmethods 6732 // as visited when we scan the strong code root lists during the GC. 6733 hr->add_strong_code_root(_nm); 6734 assert(hr->rem_set()->strong_code_roots_list_contains(_nm), 6735 err_msg("failed to add code root "PTR_FORMAT" to remembered set of region "HR_FORMAT, 6736 _nm, HR_FORMAT_PARAMS(hr))); 6737 } 6738 } 6739 6740 public: 6741 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 6742 _g1h(g1h), _nm(nm) {} 6743 6744 void do_oop(oop* p) { do_oop_work(p); } 6745 void do_oop(narrowOop* p) { do_oop_work(p); } 6746 }; 6747 6748 class UnregisterNMethodOopClosure: public OopClosure { 6749 G1CollectedHeap* _g1h; 6750 nmethod* _nm; 6751 6752 template <class T> void do_oop_work(T* p) { 6753 T heap_oop = oopDesc::load_heap_oop(p); 6754 if (!oopDesc::is_null(heap_oop)) { 6755 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 6756 HeapRegion* hr = _g1h->heap_region_containing(obj); 6757 assert(!hr->continuesHumongous(), 6758 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT 6759 " starting at "HR_FORMAT, 6760 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()))); 6761 6762 hr->remove_strong_code_root(_nm); 6763 assert(!hr->rem_set()->strong_code_roots_list_contains(_nm), 6764 err_msg("failed to remove code root "PTR_FORMAT" of region "HR_FORMAT, 6765 _nm, HR_FORMAT_PARAMS(hr))); 6766 } 6767 } 6768 6769 public: 6770 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 6771 _g1h(g1h), _nm(nm) {} 6772 6773 void do_oop(oop* p) { do_oop_work(p); } 6774 void do_oop(narrowOop* p) { do_oop_work(p); } 6775 }; 6776 6777 void G1CollectedHeap::register_nmethod(nmethod* nm) { 6778 CollectedHeap::register_nmethod(nm); 6779 6780 guarantee(nm != NULL, "sanity"); 6781 RegisterNMethodOopClosure reg_cl(this, nm); 6782 nm->oops_do(®_cl); 6783 } 6784 6785 void G1CollectedHeap::unregister_nmethod(nmethod* nm) { 6786 CollectedHeap::unregister_nmethod(nm); 6787 6788 guarantee(nm != NULL, "sanity"); 6789 UnregisterNMethodOopClosure reg_cl(this, nm); 6790 nm->oops_do(®_cl, true); 6791 } 6792 6793 class MigrateCodeRootsHeapRegionClosure: public HeapRegionClosure { 6794 public: 6795 bool doHeapRegion(HeapRegion *hr) { 6796 assert(!hr->isHumongous(), 6797 err_msg("humongous region "HR_FORMAT" should not have been added to collection set", 6798 HR_FORMAT_PARAMS(hr))); 6799 hr->migrate_strong_code_roots(); 6800 return false; 6801 } 6802 }; 6803 6804 void G1CollectedHeap::migrate_strong_code_roots() { 6805 MigrateCodeRootsHeapRegionClosure cl; 6806 double migrate_start = os::elapsedTime(); 6807 collection_set_iterate(&cl); 6808 double migration_time_ms = (os::elapsedTime() - migrate_start) * 1000.0; 6809 g1_policy()->phase_times()->record_strong_code_root_migration_time(migration_time_ms); 6810 } 6811 6812 void G1CollectedHeap::purge_code_root_memory() { 6813 double purge_start = os::elapsedTime(); 6814 G1CodeRootSet::purge_chunks(G1CodeRootsChunkCacheKeepPercent); 6815 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0; 6816 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms); 6817 } 6818 6819 // Mark all the code roots that point into regions *not* in the 6820 // collection set. 6821 // 6822 // Note we do not want to use a "marking" CodeBlobToOopClosure while 6823 // walking the the code roots lists of regions not in the collection 6824 // set. Suppose we have an nmethod (M) that points to objects in two 6825 // separate regions - one in the collection set (R1) and one not (R2). 6826 // Using a "marking" CodeBlobToOopClosure here would result in "marking" 6827 // nmethod M when walking the code roots for R1. When we come to scan 6828 // the code roots for R2, we would see that M is already marked and it 6829 // would be skipped and the objects in R2 that are referenced from M 6830 // would not be evacuated. 6831 6832 class MarkStrongCodeRootCodeBlobClosure: public CodeBlobClosure { 6833 6834 class MarkStrongCodeRootOopClosure: public OopClosure { 6835 ConcurrentMark* _cm; 6836 HeapRegion* _hr; 6837 uint _worker_id; 6838 6839 template <class T> void do_oop_work(T* p) { 6840 T heap_oop = oopDesc::load_heap_oop(p); 6841 if (!oopDesc::is_null(heap_oop)) { 6842 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 6843 // Only mark objects in the region (which is assumed 6844 // to be not in the collection set). 6845 if (_hr->is_in(obj)) { 6846 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id); 6847 } 6848 } 6849 } 6850 6851 public: 6852 MarkStrongCodeRootOopClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id) : 6853 _cm(cm), _hr(hr), _worker_id(worker_id) { 6854 assert(!_hr->in_collection_set(), "sanity"); 6855 } 6856 6857 void do_oop(narrowOop* p) { do_oop_work(p); } 6858 void do_oop(oop* p) { do_oop_work(p); } 6859 }; 6860 6861 MarkStrongCodeRootOopClosure _oop_cl; 6862 6863 public: 6864 MarkStrongCodeRootCodeBlobClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id): 6865 _oop_cl(cm, hr, worker_id) {} 6866 6867 void do_code_blob(CodeBlob* cb) { 6868 nmethod* nm = (cb == NULL) ? NULL : cb->as_nmethod_or_null(); 6869 if (nm != NULL) { 6870 nm->oops_do(&_oop_cl); 6871 } 6872 } 6873 }; 6874 6875 class MarkStrongCodeRootsHRClosure: public HeapRegionClosure { 6876 G1CollectedHeap* _g1h; 6877 uint _worker_id; 6878 6879 public: 6880 MarkStrongCodeRootsHRClosure(G1CollectedHeap* g1h, uint worker_id) : 6881 _g1h(g1h), _worker_id(worker_id) {} 6882 6883 bool doHeapRegion(HeapRegion *hr) { 6884 HeapRegionRemSet* hrrs = hr->rem_set(); 6885 if (hr->continuesHumongous()) { 6886 // Code roots should never be attached to a continuation of a humongous region 6887 assert(hrrs->strong_code_roots_list_length() == 0, 6888 err_msg("code roots should never be attached to continuations of humongous region "HR_FORMAT 6889 " starting at "HR_FORMAT", but has "SIZE_FORMAT, 6890 HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()), 6891 hrrs->strong_code_roots_list_length())); 6892 return false; 6893 } 6894 6895 if (hr->in_collection_set()) { 6896 // Don't mark code roots into regions in the collection set here. 6897 // They will be marked when we scan them. 6898 return false; 6899 } 6900 6901 MarkStrongCodeRootCodeBlobClosure cb_cl(_g1h->concurrent_mark(), hr, _worker_id); 6902 hr->strong_code_roots_do(&cb_cl); 6903 return false; 6904 } 6905 }; 6906 6907 void G1CollectedHeap::mark_strong_code_roots(uint worker_id) { 6908 MarkStrongCodeRootsHRClosure cl(this, worker_id); 6909 if (G1CollectedHeap::use_parallel_gc_threads()) { 6910 heap_region_par_iterate_chunked(&cl, 6911 worker_id, 6912 workers()->active_workers(), 6913 HeapRegion::ParMarkRootClaimValue); 6914 } else { 6915 heap_region_iterate(&cl); 6916 } 6917 } 6918 6919 class RebuildStrongCodeRootClosure: public CodeBlobClosure { 6920 G1CollectedHeap* _g1h; 6921 6922 public: 6923 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) : 6924 _g1h(g1h) {} 6925 6926 void do_code_blob(CodeBlob* cb) { 6927 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL; 6928 if (nm == NULL) { 6929 return; 6930 } 6931 6932 if (ScavengeRootsInCode) { 6933 _g1h->register_nmethod(nm); 6934 } 6935 } 6936 }; 6937 6938 void G1CollectedHeap::rebuild_strong_code_roots() { 6939 RebuildStrongCodeRootClosure blob_cl(this); 6940 CodeCache::blobs_do(&blob_cl); 6941 }