1 /* 2 * Copyright (c) 2001, 2014, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "code/codeCache.hpp" 27 #include "code/icBuffer.hpp" 28 #include "gc_implementation/g1/bufferingOopClosure.hpp" 29 #include "gc_implementation/g1/concurrentG1Refine.hpp" 30 #include "gc_implementation/g1/concurrentG1RefineThread.hpp" 31 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp" 32 #include "gc_implementation/g1/g1AllocRegion.inline.hpp" 33 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp" 34 #include "gc_implementation/g1/g1CollectorPolicy.hpp" 35 #include "gc_implementation/g1/g1ErgoVerbose.hpp" 36 #include "gc_implementation/g1/g1EvacFailure.hpp" 37 #include "gc_implementation/g1/g1GCPhaseTimes.hpp" 38 #include "gc_implementation/g1/g1Log.hpp" 39 #include "gc_implementation/g1/g1MarkSweep.hpp" 40 #include "gc_implementation/g1/g1OopClosures.inline.hpp" 41 #include "gc_implementation/g1/g1RemSet.inline.hpp" 42 #include "gc_implementation/g1/g1YCTypes.hpp" 43 #include "gc_implementation/g1/heapRegion.inline.hpp" 44 #include "gc_implementation/g1/heapRegionRemSet.hpp" 45 #include "gc_implementation/g1/heapRegionSeq.inline.hpp" 46 #include "gc_implementation/g1/vm_operations_g1.hpp" 47 #include "gc_implementation/shared/gcHeapSummary.hpp" 48 #include "gc_implementation/shared/gcTimer.hpp" 49 #include "gc_implementation/shared/gcTrace.hpp" 50 #include "gc_implementation/shared/gcTraceTime.hpp" 51 #include "gc_implementation/shared/isGCActiveMark.hpp" 52 #include "memory/gcLocker.inline.hpp" 53 #include "memory/generationSpec.hpp" 54 #include "memory/iterator.hpp" 55 #include "memory/referenceProcessor.hpp" 56 #include "oops/oop.inline.hpp" 57 #include "oops/oop.pcgc.inline.hpp" 58 #include "runtime/vmThread.hpp" 59 #include "utilities/ticks.hpp" 60 61 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0; 62 63 // turn it on so that the contents of the young list (scan-only / 64 // to-be-collected) are printed at "strategic" points before / during 65 // / after the collection --- this is useful for debugging 66 #define YOUNG_LIST_VERBOSE 0 67 // CURRENT STATUS 68 // This file is under construction. Search for "FIXME". 69 70 // INVARIANTS/NOTES 71 // 72 // All allocation activity covered by the G1CollectedHeap interface is 73 // serialized by acquiring the HeapLock. This happens in mem_allocate 74 // and allocate_new_tlab, which are the "entry" points to the 75 // allocation code from the rest of the JVM. (Note that this does not 76 // apply to TLAB allocation, which is not part of this interface: it 77 // is done by clients of this interface.) 78 79 // Notes on implementation of parallelism in different tasks. 80 // 81 // G1ParVerifyTask uses heap_region_par_iterate_chunked() for parallelism. 82 // The number of GC workers is passed to heap_region_par_iterate_chunked(). 83 // It does use run_task() which sets _n_workers in the task. 84 // G1ParTask executes g1_process_strong_roots() -> 85 // SharedHeap::process_strong_roots() which calls eventually to 86 // CardTableModRefBS::par_non_clean_card_iterate_work() which uses 87 // SequentialSubTasksDone. SharedHeap::process_strong_roots() also 88 // directly uses SubTasksDone (_process_strong_tasks field in SharedHeap). 89 // 90 91 // Local to this file. 92 93 class RefineCardTableEntryClosure: public CardTableEntryClosure { 94 SuspendibleThreadSet* _sts; 95 G1RemSet* _g1rs; 96 ConcurrentG1Refine* _cg1r; 97 bool _concurrent; 98 public: 99 RefineCardTableEntryClosure(SuspendibleThreadSet* sts, 100 G1RemSet* g1rs, 101 ConcurrentG1Refine* cg1r) : 102 _sts(sts), _g1rs(g1rs), _cg1r(cg1r), _concurrent(true) 103 {} 104 bool do_card_ptr(jbyte* card_ptr, int worker_i) { 105 bool oops_into_cset = _g1rs->refine_card(card_ptr, worker_i, false); 106 // This path is executed by the concurrent refine or mutator threads, 107 // concurrently, and so we do not care if card_ptr contains references 108 // that point into the collection set. 109 assert(!oops_into_cset, "should be"); 110 111 if (_concurrent && _sts->should_yield()) { 112 // Caller will actually yield. 113 return false; 114 } 115 // Otherwise, we finished successfully; return true. 116 return true; 117 } 118 void set_concurrent(bool b) { _concurrent = b; } 119 }; 120 121 122 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure { 123 int _calls; 124 G1CollectedHeap* _g1h; 125 CardTableModRefBS* _ctbs; 126 int _histo[256]; 127 public: 128 ClearLoggedCardTableEntryClosure() : 129 _calls(0), _g1h(G1CollectedHeap::heap()), _ctbs(_g1h->g1_barrier_set()) 130 { 131 for (int i = 0; i < 256; i++) _histo[i] = 0; 132 } 133 bool do_card_ptr(jbyte* card_ptr, int worker_i) { 134 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) { 135 _calls++; 136 unsigned char* ujb = (unsigned char*)card_ptr; 137 int ind = (int)(*ujb); 138 _histo[ind]++; 139 *card_ptr = -1; 140 } 141 return true; 142 } 143 int calls() { return _calls; } 144 void print_histo() { 145 gclog_or_tty->print_cr("Card table value histogram:"); 146 for (int i = 0; i < 256; i++) { 147 if (_histo[i] != 0) { 148 gclog_or_tty->print_cr(" %d: %d", i, _histo[i]); 149 } 150 } 151 } 152 }; 153 154 class RedirtyLoggedCardTableEntryClosure: public CardTableEntryClosure { 155 int _calls; 156 G1CollectedHeap* _g1h; 157 CardTableModRefBS* _ctbs; 158 public: 159 RedirtyLoggedCardTableEntryClosure() : 160 _calls(0), _g1h(G1CollectedHeap::heap()), _ctbs(_g1h->g1_barrier_set()) {} 161 162 bool do_card_ptr(jbyte* card_ptr, int worker_i) { 163 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) { 164 _calls++; 165 *card_ptr = 0; 166 } 167 return true; 168 } 169 int calls() { return _calls; } 170 }; 171 172 class RedirtyLoggedCardTableEntryFastClosure : public CardTableEntryClosure { 173 public: 174 bool do_card_ptr(jbyte* card_ptr, int worker_i) { 175 *card_ptr = CardTableModRefBS::dirty_card_val(); 176 return true; 177 } 178 }; 179 180 YoungList::YoungList(G1CollectedHeap* g1h) : 181 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0), 182 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) { 183 guarantee(check_list_empty(false), "just making sure..."); 184 } 185 186 void YoungList::push_region(HeapRegion *hr) { 187 assert(!hr->is_young(), "should not already be young"); 188 assert(hr->get_next_young_region() == NULL, "cause it should!"); 189 190 hr->set_next_young_region(_head); 191 _head = hr; 192 193 _g1h->g1_policy()->set_region_eden(hr, (int) _length); 194 ++_length; 195 } 196 197 void YoungList::add_survivor_region(HeapRegion* hr) { 198 assert(hr->is_survivor(), "should be flagged as survivor region"); 199 assert(hr->get_next_young_region() == NULL, "cause it should!"); 200 201 hr->set_next_young_region(_survivor_head); 202 if (_survivor_head == NULL) { 203 _survivor_tail = hr; 204 } 205 _survivor_head = hr; 206 ++_survivor_length; 207 } 208 209 void YoungList::empty_list(HeapRegion* list) { 210 while (list != NULL) { 211 HeapRegion* next = list->get_next_young_region(); 212 list->set_next_young_region(NULL); 213 list->uninstall_surv_rate_group(); 214 list->set_not_young(); 215 list = next; 216 } 217 } 218 219 void YoungList::empty_list() { 220 assert(check_list_well_formed(), "young list should be well formed"); 221 222 empty_list(_head); 223 _head = NULL; 224 _length = 0; 225 226 empty_list(_survivor_head); 227 _survivor_head = NULL; 228 _survivor_tail = NULL; 229 _survivor_length = 0; 230 231 _last_sampled_rs_lengths = 0; 232 233 assert(check_list_empty(false), "just making sure..."); 234 } 235 236 bool YoungList::check_list_well_formed() { 237 bool ret = true; 238 239 uint length = 0; 240 HeapRegion* curr = _head; 241 HeapRegion* last = NULL; 242 while (curr != NULL) { 243 if (!curr->is_young()) { 244 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" " 245 "incorrectly tagged (y: %d, surv: %d)", 246 curr->bottom(), curr->end(), 247 curr->is_young(), curr->is_survivor()); 248 ret = false; 249 } 250 ++length; 251 last = curr; 252 curr = curr->get_next_young_region(); 253 } 254 ret = ret && (length == _length); 255 256 if (!ret) { 257 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!"); 258 gclog_or_tty->print_cr("### list has %u entries, _length is %u", 259 length, _length); 260 } 261 262 return ret; 263 } 264 265 bool YoungList::check_list_empty(bool check_sample) { 266 bool ret = true; 267 268 if (_length != 0) { 269 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u", 270 _length); 271 ret = false; 272 } 273 if (check_sample && _last_sampled_rs_lengths != 0) { 274 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths"); 275 ret = false; 276 } 277 if (_head != NULL) { 278 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head"); 279 ret = false; 280 } 281 if (!ret) { 282 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty"); 283 } 284 285 return ret; 286 } 287 288 void 289 YoungList::rs_length_sampling_init() { 290 _sampled_rs_lengths = 0; 291 _curr = _head; 292 } 293 294 bool 295 YoungList::rs_length_sampling_more() { 296 return _curr != NULL; 297 } 298 299 void 300 YoungList::rs_length_sampling_next() { 301 assert( _curr != NULL, "invariant" ); 302 size_t rs_length = _curr->rem_set()->occupied(); 303 304 _sampled_rs_lengths += rs_length; 305 306 // The current region may not yet have been added to the 307 // incremental collection set (it gets added when it is 308 // retired as the current allocation region). 309 if (_curr->in_collection_set()) { 310 // Update the collection set policy information for this region 311 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length); 312 } 313 314 _curr = _curr->get_next_young_region(); 315 if (_curr == NULL) { 316 _last_sampled_rs_lengths = _sampled_rs_lengths; 317 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths); 318 } 319 } 320 321 void 322 YoungList::reset_auxilary_lists() { 323 guarantee( is_empty(), "young list should be empty" ); 324 assert(check_list_well_formed(), "young list should be well formed"); 325 326 // Add survivor regions to SurvRateGroup. 327 _g1h->g1_policy()->note_start_adding_survivor_regions(); 328 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */); 329 330 int young_index_in_cset = 0; 331 for (HeapRegion* curr = _survivor_head; 332 curr != NULL; 333 curr = curr->get_next_young_region()) { 334 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset); 335 336 // The region is a non-empty survivor so let's add it to 337 // the incremental collection set for the next evacuation 338 // pause. 339 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr); 340 young_index_in_cset += 1; 341 } 342 assert((uint) young_index_in_cset == _survivor_length, "post-condition"); 343 _g1h->g1_policy()->note_stop_adding_survivor_regions(); 344 345 _head = _survivor_head; 346 _length = _survivor_length; 347 if (_survivor_head != NULL) { 348 assert(_survivor_tail != NULL, "cause it shouldn't be"); 349 assert(_survivor_length > 0, "invariant"); 350 _survivor_tail->set_next_young_region(NULL); 351 } 352 353 // Don't clear the survivor list handles until the start of 354 // the next evacuation pause - we need it in order to re-tag 355 // the survivor regions from this evacuation pause as 'young' 356 // at the start of the next. 357 358 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */); 359 360 assert(check_list_well_formed(), "young list should be well formed"); 361 } 362 363 void YoungList::print() { 364 HeapRegion* lists[] = {_head, _survivor_head}; 365 const char* names[] = {"YOUNG", "SURVIVOR"}; 366 367 for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) { 368 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]); 369 HeapRegion *curr = lists[list]; 370 if (curr == NULL) 371 gclog_or_tty->print_cr(" empty"); 372 while (curr != NULL) { 373 gclog_or_tty->print_cr(" "HR_FORMAT", P: "PTR_FORMAT "N: "PTR_FORMAT", age: %4d", 374 HR_FORMAT_PARAMS(curr), 375 curr->prev_top_at_mark_start(), 376 curr->next_top_at_mark_start(), 377 curr->age_in_surv_rate_group_cond()); 378 curr = curr->get_next_young_region(); 379 } 380 } 381 382 gclog_or_tty->print_cr(""); 383 } 384 385 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr) 386 { 387 // Claim the right to put the region on the dirty cards region list 388 // by installing a self pointer. 389 HeapRegion* next = hr->get_next_dirty_cards_region(); 390 if (next == NULL) { 391 HeapRegion* res = (HeapRegion*) 392 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(), 393 NULL); 394 if (res == NULL) { 395 HeapRegion* head; 396 do { 397 // Put the region to the dirty cards region list. 398 head = _dirty_cards_region_list; 399 next = (HeapRegion*) 400 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head); 401 if (next == head) { 402 assert(hr->get_next_dirty_cards_region() == hr, 403 "hr->get_next_dirty_cards_region() != hr"); 404 if (next == NULL) { 405 // The last region in the list points to itself. 406 hr->set_next_dirty_cards_region(hr); 407 } else { 408 hr->set_next_dirty_cards_region(next); 409 } 410 } 411 } while (next != head); 412 } 413 } 414 } 415 416 HeapRegion* G1CollectedHeap::pop_dirty_cards_region() 417 { 418 HeapRegion* head; 419 HeapRegion* hr; 420 do { 421 head = _dirty_cards_region_list; 422 if (head == NULL) { 423 return NULL; 424 } 425 HeapRegion* new_head = head->get_next_dirty_cards_region(); 426 if (head == new_head) { 427 // The last region. 428 new_head = NULL; 429 } 430 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list, 431 head); 432 } while (hr != head); 433 assert(hr != NULL, "invariant"); 434 hr->set_next_dirty_cards_region(NULL); 435 return hr; 436 } 437 438 void G1CollectedHeap::stop_conc_gc_threads() { 439 _cg1r->stop(); 440 _cmThread->stop(); 441 } 442 443 #ifdef ASSERT 444 // A region is added to the collection set as it is retired 445 // so an address p can point to a region which will be in the 446 // collection set but has not yet been retired. This method 447 // therefore is only accurate during a GC pause after all 448 // regions have been retired. It is used for debugging 449 // to check if an nmethod has references to objects that can 450 // be move during a partial collection. Though it can be 451 // inaccurate, it is sufficient for G1 because the conservative 452 // implementation of is_scavengable() for G1 will indicate that 453 // all nmethods must be scanned during a partial collection. 454 bool G1CollectedHeap::is_in_partial_collection(const void* p) { 455 HeapRegion* hr = heap_region_containing(p); 456 return hr != NULL && hr->in_collection_set(); 457 } 458 #endif 459 460 // Returns true if the reference points to an object that 461 // can move in an incremental collection. 462 bool G1CollectedHeap::is_scavengable(const void* p) { 463 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 464 G1CollectorPolicy* g1p = g1h->g1_policy(); 465 HeapRegion* hr = heap_region_containing(p); 466 if (hr == NULL) { 467 // null 468 assert(p == NULL, err_msg("Not NULL " PTR_FORMAT ,p)); 469 return false; 470 } else { 471 return !hr->isHumongous(); 472 } 473 } 474 475 void G1CollectedHeap::check_ct_logs_at_safepoint() { 476 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 477 CardTableModRefBS* ct_bs = g1_barrier_set(); 478 479 // Count the dirty cards at the start. 480 CountNonCleanMemRegionClosure count1(this); 481 ct_bs->mod_card_iterate(&count1); 482 int orig_count = count1.n(); 483 484 // First clear the logged cards. 485 ClearLoggedCardTableEntryClosure clear; 486 dcqs.set_closure(&clear); 487 dcqs.apply_closure_to_all_completed_buffers(); 488 dcqs.iterate_closure_all_threads(false); 489 clear.print_histo(); 490 491 // Now ensure that there's no dirty cards. 492 CountNonCleanMemRegionClosure count2(this); 493 ct_bs->mod_card_iterate(&count2); 494 if (count2.n() != 0) { 495 gclog_or_tty->print_cr("Card table has %d entries; %d originally", 496 count2.n(), orig_count); 497 } 498 guarantee(count2.n() == 0, "Card table should be clean."); 499 500 RedirtyLoggedCardTableEntryClosure redirty; 501 JavaThread::dirty_card_queue_set().set_closure(&redirty); 502 dcqs.apply_closure_to_all_completed_buffers(); 503 dcqs.iterate_closure_all_threads(false); 504 gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.", 505 clear.calls(), orig_count); 506 guarantee(redirty.calls() == clear.calls(), 507 "Or else mechanism is broken."); 508 509 CountNonCleanMemRegionClosure count3(this); 510 ct_bs->mod_card_iterate(&count3); 511 if (count3.n() != orig_count) { 512 gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.", 513 orig_count, count3.n()); 514 guarantee(count3.n() >= orig_count, "Should have restored them all."); 515 } 516 517 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl); 518 } 519 520 // Private class members. 521 522 G1CollectedHeap* G1CollectedHeap::_g1h; 523 524 // Private methods. 525 526 HeapRegion* 527 G1CollectedHeap::new_region_try_secondary_free_list() { 528 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 529 while (!_secondary_free_list.is_empty() || free_regions_coming()) { 530 if (!_secondary_free_list.is_empty()) { 531 if (G1ConcRegionFreeingVerbose) { 532 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 533 "secondary_free_list has %u entries", 534 _secondary_free_list.length()); 535 } 536 // It looks as if there are free regions available on the 537 // secondary_free_list. Let's move them to the free_list and try 538 // again to allocate from it. 539 append_secondary_free_list(); 540 541 assert(!_free_list.is_empty(), "if the secondary_free_list was not " 542 "empty we should have moved at least one entry to the free_list"); 543 HeapRegion* res = _free_list.remove_head(); 544 if (G1ConcRegionFreeingVerbose) { 545 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 546 "allocated "HR_FORMAT" from secondary_free_list", 547 HR_FORMAT_PARAMS(res)); 548 } 549 return res; 550 } 551 552 // Wait here until we get notified either when (a) there are no 553 // more free regions coming or (b) some regions have been moved on 554 // the secondary_free_list. 555 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 556 } 557 558 if (G1ConcRegionFreeingVerbose) { 559 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 560 "could not allocate from secondary_free_list"); 561 } 562 return NULL; 563 } 564 565 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool do_expand) { 566 assert(!isHumongous(word_size) || word_size <= HeapRegion::GrainWords, 567 "the only time we use this to allocate a humongous region is " 568 "when we are allocating a single humongous region"); 569 570 HeapRegion* res; 571 if (G1StressConcRegionFreeing) { 572 if (!_secondary_free_list.is_empty()) { 573 if (G1ConcRegionFreeingVerbose) { 574 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 575 "forced to look at the secondary_free_list"); 576 } 577 res = new_region_try_secondary_free_list(); 578 if (res != NULL) { 579 return res; 580 } 581 } 582 } 583 res = _free_list.remove_head_or_null(); 584 if (res == NULL) { 585 if (G1ConcRegionFreeingVerbose) { 586 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 587 "res == NULL, trying the secondary_free_list"); 588 } 589 res = new_region_try_secondary_free_list(); 590 } 591 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) { 592 // Currently, only attempts to allocate GC alloc regions set 593 // do_expand to true. So, we should only reach here during a 594 // safepoint. If this assumption changes we might have to 595 // reconsider the use of _expand_heap_after_alloc_failure. 596 assert(SafepointSynchronize::is_at_safepoint(), "invariant"); 597 598 ergo_verbose1(ErgoHeapSizing, 599 "attempt heap expansion", 600 ergo_format_reason("region allocation request failed") 601 ergo_format_byte("allocation request"), 602 word_size * HeapWordSize); 603 if (expand(word_size * HeapWordSize)) { 604 // Given that expand() succeeded in expanding the heap, and we 605 // always expand the heap by an amount aligned to the heap 606 // region size, the free list should in theory not be empty. So 607 // it would probably be OK to use remove_head(). But the extra 608 // check for NULL is unlikely to be a performance issue here (we 609 // just expanded the heap!) so let's just be conservative and 610 // use remove_head_or_null(). 611 res = _free_list.remove_head_or_null(); 612 } else { 613 _expand_heap_after_alloc_failure = false; 614 } 615 } 616 return res; 617 } 618 619 uint G1CollectedHeap::humongous_obj_allocate_find_first(uint num_regions, 620 size_t word_size) { 621 assert(isHumongous(word_size), "word_size should be humongous"); 622 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition"); 623 624 uint first = G1_NULL_HRS_INDEX; 625 if (num_regions == 1) { 626 // Only one region to allocate, no need to go through the slower 627 // path. The caller will attempt the expansion if this fails, so 628 // let's not try to expand here too. 629 HeapRegion* hr = new_region(word_size, false /* do_expand */); 630 if (hr != NULL) { 631 first = hr->hrs_index(); 632 } else { 633 first = G1_NULL_HRS_INDEX; 634 } 635 } else { 636 // We can't allocate humongous regions while cleanupComplete() is 637 // running, since some of the regions we find to be empty might not 638 // yet be added to the free list and it is not straightforward to 639 // know which list they are on so that we can remove them. Note 640 // that we only need to do this if we need to allocate more than 641 // one region to satisfy the current humongous allocation 642 // request. If we are only allocating one region we use the common 643 // region allocation code (see above). 644 wait_while_free_regions_coming(); 645 append_secondary_free_list_if_not_empty_with_lock(); 646 647 if (free_regions() >= num_regions) { 648 first = _hrs.find_contiguous(num_regions); 649 if (first != G1_NULL_HRS_INDEX) { 650 for (uint i = first; i < first + num_regions; ++i) { 651 HeapRegion* hr = region_at(i); 652 assert(hr->is_empty(), "sanity"); 653 assert(is_on_master_free_list(hr), "sanity"); 654 hr->set_pending_removal(true); 655 } 656 _free_list.remove_all_pending(num_regions); 657 } 658 } 659 } 660 return first; 661 } 662 663 HeapWord* 664 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first, 665 uint num_regions, 666 size_t word_size) { 667 assert(first != G1_NULL_HRS_INDEX, "pre-condition"); 668 assert(isHumongous(word_size), "word_size should be humongous"); 669 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition"); 670 671 // Index of last region in the series + 1. 672 uint last = first + num_regions; 673 674 // We need to initialize the region(s) we just discovered. This is 675 // a bit tricky given that it can happen concurrently with 676 // refinement threads refining cards on these regions and 677 // potentially wanting to refine the BOT as they are scanning 678 // those cards (this can happen shortly after a cleanup; see CR 679 // 6991377). So we have to set up the region(s) carefully and in 680 // a specific order. 681 682 // The word size sum of all the regions we will allocate. 683 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords; 684 assert(word_size <= word_size_sum, "sanity"); 685 686 // This will be the "starts humongous" region. 687 HeapRegion* first_hr = region_at(first); 688 // The header of the new object will be placed at the bottom of 689 // the first region. 690 HeapWord* new_obj = first_hr->bottom(); 691 // This will be the new end of the first region in the series that 692 // should also match the end of the last region in the series. 693 HeapWord* new_end = new_obj + word_size_sum; 694 // This will be the new top of the first region that will reflect 695 // this allocation. 696 HeapWord* new_top = new_obj + word_size; 697 698 // First, we need to zero the header of the space that we will be 699 // allocating. When we update top further down, some refinement 700 // threads might try to scan the region. By zeroing the header we 701 // ensure that any thread that will try to scan the region will 702 // come across the zero klass word and bail out. 703 // 704 // NOTE: It would not have been correct to have used 705 // CollectedHeap::fill_with_object() and make the space look like 706 // an int array. The thread that is doing the allocation will 707 // later update the object header to a potentially different array 708 // type and, for a very short period of time, the klass and length 709 // fields will be inconsistent. This could cause a refinement 710 // thread to calculate the object size incorrectly. 711 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0); 712 713 // We will set up the first region as "starts humongous". This 714 // will also update the BOT covering all the regions to reflect 715 // that there is a single object that starts at the bottom of the 716 // first region. 717 first_hr->set_startsHumongous(new_top, new_end); 718 719 // Then, if there are any, we will set up the "continues 720 // humongous" regions. 721 HeapRegion* hr = NULL; 722 for (uint i = first + 1; i < last; ++i) { 723 hr = region_at(i); 724 hr->set_continuesHumongous(first_hr); 725 } 726 // If we have "continues humongous" regions (hr != NULL), then the 727 // end of the last one should match new_end. 728 assert(hr == NULL || hr->end() == new_end, "sanity"); 729 730 // Up to this point no concurrent thread would have been able to 731 // do any scanning on any region in this series. All the top 732 // fields still point to bottom, so the intersection between 733 // [bottom,top] and [card_start,card_end] will be empty. Before we 734 // update the top fields, we'll do a storestore to make sure that 735 // no thread sees the update to top before the zeroing of the 736 // object header and the BOT initialization. 737 OrderAccess::storestore(); 738 739 // Now that the BOT and the object header have been initialized, 740 // we can update top of the "starts humongous" region. 741 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(), 742 "new_top should be in this region"); 743 first_hr->set_top(new_top); 744 if (_hr_printer.is_active()) { 745 HeapWord* bottom = first_hr->bottom(); 746 HeapWord* end = first_hr->orig_end(); 747 if ((first + 1) == last) { 748 // the series has a single humongous region 749 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top); 750 } else { 751 // the series has more than one humongous regions 752 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end); 753 } 754 } 755 756 // Now, we will update the top fields of the "continues humongous" 757 // regions. The reason we need to do this is that, otherwise, 758 // these regions would look empty and this will confuse parts of 759 // G1. For example, the code that looks for a consecutive number 760 // of empty regions will consider them empty and try to 761 // re-allocate them. We can extend is_empty() to also include 762 // !continuesHumongous(), but it is easier to just update the top 763 // fields here. The way we set top for all regions (i.e., top == 764 // end for all regions but the last one, top == new_top for the 765 // last one) is actually used when we will free up the humongous 766 // region in free_humongous_region(). 767 hr = NULL; 768 for (uint i = first + 1; i < last; ++i) { 769 hr = region_at(i); 770 if ((i + 1) == last) { 771 // last continues humongous region 772 assert(hr->bottom() < new_top && new_top <= hr->end(), 773 "new_top should fall on this region"); 774 hr->set_top(new_top); 775 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top); 776 } else { 777 // not last one 778 assert(new_top > hr->end(), "new_top should be above this region"); 779 hr->set_top(hr->end()); 780 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end()); 781 } 782 } 783 // If we have continues humongous regions (hr != NULL), then the 784 // end of the last one should match new_end and its top should 785 // match new_top. 786 assert(hr == NULL || 787 (hr->end() == new_end && hr->top() == new_top), "sanity"); 788 789 assert(first_hr->used() == word_size * HeapWordSize, "invariant"); 790 _summary_bytes_used += first_hr->used(); 791 _humongous_set.add(first_hr); 792 793 return new_obj; 794 } 795 796 // If could fit into free regions w/o expansion, try. 797 // Otherwise, if can expand, do so. 798 // Otherwise, if using ex regions might help, try with ex given back. 799 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) { 800 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 801 802 verify_region_sets_optional(); 803 804 size_t word_size_rounded = round_to(word_size, HeapRegion::GrainWords); 805 uint num_regions = (uint) (word_size_rounded / HeapRegion::GrainWords); 806 uint x_num = expansion_regions(); 807 uint fs = _hrs.free_suffix(); 808 uint first = humongous_obj_allocate_find_first(num_regions, word_size); 809 if (first == G1_NULL_HRS_INDEX) { 810 // The only thing we can do now is attempt expansion. 811 if (fs + x_num >= num_regions) { 812 // If the number of regions we're trying to allocate for this 813 // object is at most the number of regions in the free suffix, 814 // then the call to humongous_obj_allocate_find_first() above 815 // should have succeeded and we wouldn't be here. 816 // 817 // We should only be trying to expand when the free suffix is 818 // not sufficient for the object _and_ we have some expansion 819 // room available. 820 assert(num_regions > fs, "earlier allocation should have succeeded"); 821 822 ergo_verbose1(ErgoHeapSizing, 823 "attempt heap expansion", 824 ergo_format_reason("humongous allocation request failed") 825 ergo_format_byte("allocation request"), 826 word_size * HeapWordSize); 827 if (expand((num_regions - fs) * HeapRegion::GrainBytes)) { 828 // Even though the heap was expanded, it might not have 829 // reached the desired size. So, we cannot assume that the 830 // allocation will succeed. 831 first = humongous_obj_allocate_find_first(num_regions, word_size); 832 } 833 } 834 } 835 836 HeapWord* result = NULL; 837 if (first != G1_NULL_HRS_INDEX) { 838 result = 839 humongous_obj_allocate_initialize_regions(first, num_regions, word_size); 840 assert(result != NULL, "it should always return a valid result"); 841 842 // A successful humongous object allocation changes the used space 843 // information of the old generation so we need to recalculate the 844 // sizes and update the jstat counters here. 845 g1mm()->update_sizes(); 846 } 847 848 verify_region_sets_optional(); 849 850 return result; 851 } 852 853 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) { 854 assert_heap_not_locked_and_not_at_safepoint(); 855 assert(!isHumongous(word_size), "we do not allow humongous TLABs"); 856 857 unsigned int dummy_gc_count_before; 858 int dummy_gclocker_retry_count = 0; 859 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count); 860 } 861 862 HeapWord* 863 G1CollectedHeap::mem_allocate(size_t word_size, 864 bool* gc_overhead_limit_was_exceeded) { 865 assert_heap_not_locked_and_not_at_safepoint(); 866 867 // Loop until the allocation is satisfied, or unsatisfied after GC. 868 for (int try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 869 unsigned int gc_count_before; 870 871 HeapWord* result = NULL; 872 if (!isHumongous(word_size)) { 873 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count); 874 } else { 875 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count); 876 } 877 if (result != NULL) { 878 return result; 879 } 880 881 // Create the garbage collection operation... 882 VM_G1CollectForAllocation op(gc_count_before, word_size); 883 // ...and get the VM thread to execute it. 884 VMThread::execute(&op); 885 886 if (op.prologue_succeeded() && op.pause_succeeded()) { 887 // If the operation was successful we'll return the result even 888 // if it is NULL. If the allocation attempt failed immediately 889 // after a Full GC, it's unlikely we'll be able to allocate now. 890 HeapWord* result = op.result(); 891 if (result != NULL && !isHumongous(word_size)) { 892 // Allocations that take place on VM operations do not do any 893 // card dirtying and we have to do it here. We only have to do 894 // this for non-humongous allocations, though. 895 dirty_young_block(result, word_size); 896 } 897 return result; 898 } else { 899 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 900 return NULL; 901 } 902 assert(op.result() == NULL, 903 "the result should be NULL if the VM op did not succeed"); 904 } 905 906 // Give a warning if we seem to be looping forever. 907 if ((QueuedAllocationWarningCount > 0) && 908 (try_count % QueuedAllocationWarningCount == 0)) { 909 warning("G1CollectedHeap::mem_allocate retries %d times", try_count); 910 } 911 } 912 913 ShouldNotReachHere(); 914 return NULL; 915 } 916 917 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size, 918 unsigned int *gc_count_before_ret, 919 int* gclocker_retry_count_ret) { 920 // Make sure you read the note in attempt_allocation_humongous(). 921 922 assert_heap_not_locked_and_not_at_safepoint(); 923 assert(!isHumongous(word_size), "attempt_allocation_slow() should not " 924 "be called for humongous allocation requests"); 925 926 // We should only get here after the first-level allocation attempt 927 // (attempt_allocation()) failed to allocate. 928 929 // We will loop until a) we manage to successfully perform the 930 // allocation or b) we successfully schedule a collection which 931 // fails to perform the allocation. b) is the only case when we'll 932 // return NULL. 933 HeapWord* result = NULL; 934 for (int try_count = 1; /* we'll return */; try_count += 1) { 935 bool should_try_gc; 936 unsigned int gc_count_before; 937 938 { 939 MutexLockerEx x(Heap_lock); 940 941 result = _mutator_alloc_region.attempt_allocation_locked(word_size, 942 false /* bot_updates */); 943 if (result != NULL) { 944 return result; 945 } 946 947 // If we reach here, attempt_allocation_locked() above failed to 948 // allocate a new region. So the mutator alloc region should be NULL. 949 assert(_mutator_alloc_region.get() == NULL, "only way to get here"); 950 951 if (GC_locker::is_active_and_needs_gc()) { 952 if (g1_policy()->can_expand_young_list()) { 953 // No need for an ergo verbose message here, 954 // can_expand_young_list() does this when it returns true. 955 result = _mutator_alloc_region.attempt_allocation_force(word_size, 956 false /* bot_updates */); 957 if (result != NULL) { 958 return result; 959 } 960 } 961 should_try_gc = false; 962 } else { 963 // The GCLocker may not be active but the GCLocker initiated 964 // GC may not yet have been performed (GCLocker::needs_gc() 965 // returns true). In this case we do not try this GC and 966 // wait until the GCLocker initiated GC is performed, and 967 // then retry the allocation. 968 if (GC_locker::needs_gc()) { 969 should_try_gc = false; 970 } else { 971 // Read the GC count while still holding the Heap_lock. 972 gc_count_before = total_collections(); 973 should_try_gc = true; 974 } 975 } 976 } 977 978 if (should_try_gc) { 979 bool succeeded; 980 result = do_collection_pause(word_size, gc_count_before, &succeeded, 981 GCCause::_g1_inc_collection_pause); 982 if (result != NULL) { 983 assert(succeeded, "only way to get back a non-NULL result"); 984 return result; 985 } 986 987 if (succeeded) { 988 // If we get here we successfully scheduled a collection which 989 // failed to allocate. No point in trying to allocate 990 // further. We'll just return NULL. 991 MutexLockerEx x(Heap_lock); 992 *gc_count_before_ret = total_collections(); 993 return NULL; 994 } 995 } else { 996 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { 997 MutexLockerEx x(Heap_lock); 998 *gc_count_before_ret = total_collections(); 999 return NULL; 1000 } 1001 // The GCLocker is either active or the GCLocker initiated 1002 // GC has not yet been performed. Stall until it is and 1003 // then retry the allocation. 1004 GC_locker::stall_until_clear(); 1005 (*gclocker_retry_count_ret) += 1; 1006 } 1007 1008 // We can reach here if we were unsuccessful in scheduling a 1009 // collection (because another thread beat us to it) or if we were 1010 // stalled due to the GC locker. In either can we should retry the 1011 // allocation attempt in case another thread successfully 1012 // performed a collection and reclaimed enough space. We do the 1013 // first attempt (without holding the Heap_lock) here and the 1014 // follow-on attempt will be at the start of the next loop 1015 // iteration (after taking the Heap_lock). 1016 result = _mutator_alloc_region.attempt_allocation(word_size, 1017 false /* bot_updates */); 1018 if (result != NULL) { 1019 return result; 1020 } 1021 1022 // Give a warning if we seem to be looping forever. 1023 if ((QueuedAllocationWarningCount > 0) && 1024 (try_count % QueuedAllocationWarningCount == 0)) { 1025 warning("G1CollectedHeap::attempt_allocation_slow() " 1026 "retries %d times", try_count); 1027 } 1028 } 1029 1030 ShouldNotReachHere(); 1031 return NULL; 1032 } 1033 1034 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size, 1035 unsigned int * gc_count_before_ret, 1036 int* gclocker_retry_count_ret) { 1037 // The structure of this method has a lot of similarities to 1038 // attempt_allocation_slow(). The reason these two were not merged 1039 // into a single one is that such a method would require several "if 1040 // allocation is not humongous do this, otherwise do that" 1041 // conditional paths which would obscure its flow. In fact, an early 1042 // version of this code did use a unified method which was harder to 1043 // follow and, as a result, it had subtle bugs that were hard to 1044 // track down. So keeping these two methods separate allows each to 1045 // be more readable. It will be good to keep these two in sync as 1046 // much as possible. 1047 1048 assert_heap_not_locked_and_not_at_safepoint(); 1049 assert(isHumongous(word_size), "attempt_allocation_humongous() " 1050 "should only be called for humongous allocations"); 1051 1052 // Humongous objects can exhaust the heap quickly, so we should check if we 1053 // need to start a marking cycle at each humongous object allocation. We do 1054 // the check before we do the actual allocation. The reason for doing it 1055 // before the allocation is that we avoid having to keep track of the newly 1056 // allocated memory while we do a GC. 1057 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation", 1058 word_size)) { 1059 collect(GCCause::_g1_humongous_allocation); 1060 } 1061 1062 // We will loop until a) we manage to successfully perform the 1063 // allocation or b) we successfully schedule a collection which 1064 // fails to perform the allocation. b) is the only case when we'll 1065 // return NULL. 1066 HeapWord* result = NULL; 1067 for (int try_count = 1; /* we'll return */; try_count += 1) { 1068 bool should_try_gc; 1069 unsigned int gc_count_before; 1070 1071 { 1072 MutexLockerEx x(Heap_lock); 1073 1074 // Given that humongous objects are not allocated in young 1075 // regions, we'll first try to do the allocation without doing a 1076 // collection hoping that there's enough space in the heap. 1077 result = humongous_obj_allocate(word_size); 1078 if (result != NULL) { 1079 return result; 1080 } 1081 1082 if (GC_locker::is_active_and_needs_gc()) { 1083 should_try_gc = false; 1084 } else { 1085 // The GCLocker may not be active but the GCLocker initiated 1086 // GC may not yet have been performed (GCLocker::needs_gc() 1087 // returns true). In this case we do not try this GC and 1088 // wait until the GCLocker initiated GC is performed, and 1089 // then retry the allocation. 1090 if (GC_locker::needs_gc()) { 1091 should_try_gc = false; 1092 } else { 1093 // Read the GC count while still holding the Heap_lock. 1094 gc_count_before = total_collections(); 1095 should_try_gc = true; 1096 } 1097 } 1098 } 1099 1100 if (should_try_gc) { 1101 // If we failed to allocate the humongous object, we should try to 1102 // do a collection pause (if we're allowed) in case it reclaims 1103 // enough space for the allocation to succeed after the pause. 1104 1105 bool succeeded; 1106 result = do_collection_pause(word_size, gc_count_before, &succeeded, 1107 GCCause::_g1_humongous_allocation); 1108 if (result != NULL) { 1109 assert(succeeded, "only way to get back a non-NULL result"); 1110 return result; 1111 } 1112 1113 if (succeeded) { 1114 // If we get here we successfully scheduled a collection which 1115 // failed to allocate. No point in trying to allocate 1116 // further. We'll just return NULL. 1117 MutexLockerEx x(Heap_lock); 1118 *gc_count_before_ret = total_collections(); 1119 return NULL; 1120 } 1121 } else { 1122 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { 1123 MutexLockerEx x(Heap_lock); 1124 *gc_count_before_ret = total_collections(); 1125 return NULL; 1126 } 1127 // The GCLocker is either active or the GCLocker initiated 1128 // GC has not yet been performed. Stall until it is and 1129 // then retry the allocation. 1130 GC_locker::stall_until_clear(); 1131 (*gclocker_retry_count_ret) += 1; 1132 } 1133 1134 // We can reach here if we were unsuccessful in scheduling a 1135 // collection (because another thread beat us to it) or if we were 1136 // stalled due to the GC locker. In either can we should retry the 1137 // allocation attempt in case another thread successfully 1138 // performed a collection and reclaimed enough space. Give a 1139 // warning if we seem to be looping forever. 1140 1141 if ((QueuedAllocationWarningCount > 0) && 1142 (try_count % QueuedAllocationWarningCount == 0)) { 1143 warning("G1CollectedHeap::attempt_allocation_humongous() " 1144 "retries %d times", try_count); 1145 } 1146 } 1147 1148 ShouldNotReachHere(); 1149 return NULL; 1150 } 1151 1152 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size, 1153 bool expect_null_mutator_alloc_region) { 1154 assert_at_safepoint(true /* should_be_vm_thread */); 1155 assert(_mutator_alloc_region.get() == NULL || 1156 !expect_null_mutator_alloc_region, 1157 "the current alloc region was unexpectedly found to be non-NULL"); 1158 1159 if (!isHumongous(word_size)) { 1160 return _mutator_alloc_region.attempt_allocation_locked(word_size, 1161 false /* bot_updates */); 1162 } else { 1163 HeapWord* result = humongous_obj_allocate(word_size); 1164 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) { 1165 g1_policy()->set_initiate_conc_mark_if_possible(); 1166 } 1167 return result; 1168 } 1169 1170 ShouldNotReachHere(); 1171 } 1172 1173 class PostMCRemSetClearClosure: public HeapRegionClosure { 1174 G1CollectedHeap* _g1h; 1175 ModRefBarrierSet* _mr_bs; 1176 public: 1177 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) : 1178 _g1h(g1h), _mr_bs(mr_bs) {} 1179 1180 bool doHeapRegion(HeapRegion* r) { 1181 HeapRegionRemSet* hrrs = r->rem_set(); 1182 1183 if (r->continuesHumongous()) { 1184 // We'll assert that the strong code root list and RSet is empty 1185 assert(hrrs->strong_code_roots_list_length() == 0, "sanity"); 1186 assert(hrrs->occupied() == 0, "RSet should be empty"); 1187 return false; 1188 } 1189 1190 _g1h->reset_gc_time_stamps(r); 1191 hrrs->clear(); 1192 // You might think here that we could clear just the cards 1193 // corresponding to the used region. But no: if we leave a dirty card 1194 // in a region we might allocate into, then it would prevent that card 1195 // from being enqueued, and cause it to be missed. 1196 // Re: the performance cost: we shouldn't be doing full GC anyway! 1197 _mr_bs->clear(MemRegion(r->bottom(), r->end())); 1198 1199 return false; 1200 } 1201 }; 1202 1203 void G1CollectedHeap::clear_rsets_post_compaction() { 1204 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set()); 1205 heap_region_iterate(&rs_clear); 1206 } 1207 1208 class RebuildRSOutOfRegionClosure: public HeapRegionClosure { 1209 G1CollectedHeap* _g1h; 1210 UpdateRSOopClosure _cl; 1211 int _worker_i; 1212 public: 1213 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) : 1214 _cl(g1->g1_rem_set(), worker_i), 1215 _worker_i(worker_i), 1216 _g1h(g1) 1217 { } 1218 1219 bool doHeapRegion(HeapRegion* r) { 1220 if (!r->continuesHumongous()) { 1221 _cl.set_from(r); 1222 r->oop_iterate(&_cl); 1223 } 1224 return false; 1225 } 1226 }; 1227 1228 class ParRebuildRSTask: public AbstractGangTask { 1229 G1CollectedHeap* _g1; 1230 public: 1231 ParRebuildRSTask(G1CollectedHeap* g1) 1232 : AbstractGangTask("ParRebuildRSTask"), 1233 _g1(g1) 1234 { } 1235 1236 void work(uint worker_id) { 1237 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id); 1238 _g1->heap_region_par_iterate_chunked(&rebuild_rs, worker_id, 1239 _g1->workers()->active_workers(), 1240 HeapRegion::RebuildRSClaimValue); 1241 } 1242 }; 1243 1244 class PostCompactionPrinterClosure: public HeapRegionClosure { 1245 private: 1246 G1HRPrinter* _hr_printer; 1247 public: 1248 bool doHeapRegion(HeapRegion* hr) { 1249 assert(!hr->is_young(), "not expecting to find young regions"); 1250 // We only generate output for non-empty regions. 1251 if (!hr->is_empty()) { 1252 if (!hr->isHumongous()) { 1253 _hr_printer->post_compaction(hr, G1HRPrinter::Old); 1254 } else if (hr->startsHumongous()) { 1255 if (hr->region_num() == 1) { 1256 // single humongous region 1257 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous); 1258 } else { 1259 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous); 1260 } 1261 } else { 1262 assert(hr->continuesHumongous(), "only way to get here"); 1263 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous); 1264 } 1265 } 1266 return false; 1267 } 1268 1269 PostCompactionPrinterClosure(G1HRPrinter* hr_printer) 1270 : _hr_printer(hr_printer) { } 1271 }; 1272 1273 void G1CollectedHeap::print_hrs_post_compaction() { 1274 PostCompactionPrinterClosure cl(hr_printer()); 1275 heap_region_iterate(&cl); 1276 } 1277 1278 bool G1CollectedHeap::do_collection(bool explicit_gc, 1279 bool clear_all_soft_refs, 1280 size_t word_size) { 1281 assert_at_safepoint(true /* should_be_vm_thread */); 1282 1283 if (GC_locker::check_active_before_gc()) { 1284 return false; 1285 } 1286 1287 STWGCTimer* gc_timer = G1MarkSweep::gc_timer(); 1288 gc_timer->register_gc_start(); 1289 1290 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer(); 1291 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start()); 1292 1293 SvcGCMarker sgcm(SvcGCMarker::FULL); 1294 ResourceMark rm; 1295 1296 print_heap_before_gc(); 1297 trace_heap_before_gc(gc_tracer); 1298 1299 size_t metadata_prev_used = MetaspaceAux::allocated_used_bytes(); 1300 1301 HRSPhaseSetter x(HRSPhaseFullGC); 1302 verify_region_sets_optional(); 1303 1304 const bool do_clear_all_soft_refs = clear_all_soft_refs || 1305 collector_policy()->should_clear_all_soft_refs(); 1306 1307 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy()); 1308 1309 { 1310 IsGCActiveMark x; 1311 1312 // Timing 1313 assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant"); 1314 gclog_or_tty->date_stamp(G1Log::fine() && PrintGCDateStamps); 1315 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty); 1316 1317 { 1318 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL); 1319 TraceCollectorStats tcs(g1mm()->full_collection_counters()); 1320 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause()); 1321 1322 double start = os::elapsedTime(); 1323 g1_policy()->record_full_collection_start(); 1324 1325 // Note: When we have a more flexible GC logging framework that 1326 // allows us to add optional attributes to a GC log record we 1327 // could consider timing and reporting how long we wait in the 1328 // following two methods. 1329 wait_while_free_regions_coming(); 1330 // If we start the compaction before the CM threads finish 1331 // scanning the root regions we might trip them over as we'll 1332 // be moving objects / updating references. So let's wait until 1333 // they are done. By telling them to abort, they should complete 1334 // early. 1335 _cm->root_regions()->abort(); 1336 _cm->root_regions()->wait_until_scan_finished(); 1337 append_secondary_free_list_if_not_empty_with_lock(); 1338 1339 gc_prologue(true); 1340 increment_total_collections(true /* full gc */); 1341 increment_old_marking_cycles_started(); 1342 1343 assert(used() == recalculate_used(), "Should be equal"); 1344 1345 verify_before_gc(); 1346 1347 pre_full_gc_dump(gc_timer); 1348 1349 COMPILER2_PRESENT(DerivedPointerTable::clear()); 1350 1351 // Disable discovery and empty the discovered lists 1352 // for the CM ref processor. 1353 ref_processor_cm()->disable_discovery(); 1354 ref_processor_cm()->abandon_partial_discovery(); 1355 ref_processor_cm()->verify_no_references_recorded(); 1356 1357 // Abandon current iterations of concurrent marking and concurrent 1358 // refinement, if any are in progress. We have to do this before 1359 // wait_until_scan_finished() below. 1360 concurrent_mark()->abort(); 1361 1362 // Make sure we'll choose a new allocation region afterwards. 1363 release_mutator_alloc_region(); 1364 abandon_gc_alloc_regions(); 1365 g1_rem_set()->cleanupHRRS(); 1366 1367 // We should call this after we retire any currently active alloc 1368 // regions so that all the ALLOC / RETIRE events are generated 1369 // before the start GC event. 1370 _hr_printer.start_gc(true /* full */, (size_t) total_collections()); 1371 1372 // We may have added regions to the current incremental collection 1373 // set between the last GC or pause and now. We need to clear the 1374 // incremental collection set and then start rebuilding it afresh 1375 // after this full GC. 1376 abandon_collection_set(g1_policy()->inc_cset_head()); 1377 g1_policy()->clear_incremental_cset(); 1378 g1_policy()->stop_incremental_cset_building(); 1379 1380 tear_down_region_sets(false /* free_list_only */); 1381 g1_policy()->set_gcs_are_young(true); 1382 1383 // See the comments in g1CollectedHeap.hpp and 1384 // G1CollectedHeap::ref_processing_init() about 1385 // how reference processing currently works in G1. 1386 1387 // Temporarily make discovery by the STW ref processor single threaded (non-MT). 1388 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false); 1389 1390 // Temporarily clear the STW ref processor's _is_alive_non_header field. 1391 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL); 1392 1393 ref_processor_stw()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/); 1394 ref_processor_stw()->setup_policy(do_clear_all_soft_refs); 1395 1396 // Do collection work 1397 { 1398 HandleMark hm; // Discard invalid handles created during gc 1399 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs); 1400 } 1401 1402 assert(free_regions() == 0, "we should not have added any free regions"); 1403 rebuild_region_sets(false /* free_list_only */); 1404 1405 // Enqueue any discovered reference objects that have 1406 // not been removed from the discovered lists. 1407 ref_processor_stw()->enqueue_discovered_references(); 1408 1409 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 1410 1411 MemoryService::track_memory_usage(); 1412 1413 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 1414 ref_processor_stw()->verify_no_references_recorded(); 1415 1416 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 1417 ClassLoaderDataGraph::purge(); 1418 MetaspaceAux::verify_metrics(); 1419 1420 // Note: since we've just done a full GC, concurrent 1421 // marking is no longer active. Therefore we need not 1422 // re-enable reference discovery for the CM ref processor. 1423 // That will be done at the start of the next marking cycle. 1424 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition"); 1425 ref_processor_cm()->verify_no_references_recorded(); 1426 1427 reset_gc_time_stamp(); 1428 // Since everything potentially moved, we will clear all remembered 1429 // sets, and clear all cards. Later we will rebuild remembered 1430 // sets. We will also reset the GC time stamps of the regions. 1431 clear_rsets_post_compaction(); 1432 check_gc_time_stamps(); 1433 1434 // Resize the heap if necessary. 1435 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size); 1436 1437 if (_hr_printer.is_active()) { 1438 // We should do this after we potentially resize the heap so 1439 // that all the COMMIT / UNCOMMIT events are generated before 1440 // the end GC event. 1441 1442 print_hrs_post_compaction(); 1443 _hr_printer.end_gc(true /* full */, (size_t) total_collections()); 1444 } 1445 1446 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 1447 if (hot_card_cache->use_cache()) { 1448 hot_card_cache->reset_card_counts(); 1449 hot_card_cache->reset_hot_cache(); 1450 } 1451 1452 // Rebuild remembered sets of all regions. 1453 if (G1CollectedHeap::use_parallel_gc_threads()) { 1454 uint n_workers = 1455 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 1456 workers()->active_workers(), 1457 Threads::number_of_non_daemon_threads()); 1458 assert(UseDynamicNumberOfGCThreads || 1459 n_workers == workers()->total_workers(), 1460 "If not dynamic should be using all the workers"); 1461 workers()->set_active_workers(n_workers); 1462 // Set parallel threads in the heap (_n_par_threads) only 1463 // before a parallel phase and always reset it to 0 after 1464 // the phase so that the number of parallel threads does 1465 // no get carried forward to a serial phase where there 1466 // may be code that is "possibly_parallel". 1467 set_par_threads(n_workers); 1468 1469 ParRebuildRSTask rebuild_rs_task(this); 1470 assert(check_heap_region_claim_values( 1471 HeapRegion::InitialClaimValue), "sanity check"); 1472 assert(UseDynamicNumberOfGCThreads || 1473 workers()->active_workers() == workers()->total_workers(), 1474 "Unless dynamic should use total workers"); 1475 // Use the most recent number of active workers 1476 assert(workers()->active_workers() > 0, 1477 "Active workers not properly set"); 1478 set_par_threads(workers()->active_workers()); 1479 workers()->run_task(&rebuild_rs_task); 1480 set_par_threads(0); 1481 assert(check_heap_region_claim_values( 1482 HeapRegion::RebuildRSClaimValue), "sanity check"); 1483 reset_heap_region_claim_values(); 1484 } else { 1485 RebuildRSOutOfRegionClosure rebuild_rs(this); 1486 heap_region_iterate(&rebuild_rs); 1487 } 1488 1489 // Rebuild the strong code root lists for each region 1490 rebuild_strong_code_roots(); 1491 1492 if (true) { // FIXME 1493 MetaspaceGC::compute_new_size(); 1494 } 1495 1496 #ifdef TRACESPINNING 1497 ParallelTaskTerminator::print_termination_counts(); 1498 #endif 1499 1500 // Discard all rset updates 1501 JavaThread::dirty_card_queue_set().abandon_logs(); 1502 assert(!G1DeferredRSUpdate 1503 || (G1DeferredRSUpdate && 1504 (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any"); 1505 1506 _young_list->reset_sampled_info(); 1507 // At this point there should be no regions in the 1508 // entire heap tagged as young. 1509 assert(check_young_list_empty(true /* check_heap */), 1510 "young list should be empty at this point"); 1511 1512 // Update the number of full collections that have been completed. 1513 increment_old_marking_cycles_completed(false /* concurrent */); 1514 1515 _hrs.verify_optional(); 1516 verify_region_sets_optional(); 1517 1518 verify_after_gc(); 1519 1520 // Start a new incremental collection set for the next pause 1521 assert(g1_policy()->collection_set() == NULL, "must be"); 1522 g1_policy()->start_incremental_cset_building(); 1523 1524 // Clear the _cset_fast_test bitmap in anticipation of adding 1525 // regions to the incremental collection set for the next 1526 // evacuation pause. 1527 clear_cset_fast_test(); 1528 1529 init_mutator_alloc_region(); 1530 1531 double end = os::elapsedTime(); 1532 g1_policy()->record_full_collection_end(); 1533 1534 if (G1Log::fine()) { 1535 g1_policy()->print_heap_transition(); 1536 } 1537 1538 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 1539 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 1540 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 1541 // before any GC notifications are raised. 1542 g1mm()->update_sizes(); 1543 1544 gc_epilogue(true); 1545 } 1546 1547 if (G1Log::finer()) { 1548 g1_policy()->print_detailed_heap_transition(true /* full */); 1549 } 1550 1551 print_heap_after_gc(); 1552 trace_heap_after_gc(gc_tracer); 1553 1554 post_full_gc_dump(gc_timer); 1555 1556 gc_timer->register_gc_end(); 1557 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions()); 1558 } 1559 1560 return true; 1561 } 1562 1563 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) { 1564 // do_collection() will return whether it succeeded in performing 1565 // the GC. Currently, there is no facility on the 1566 // do_full_collection() API to notify the caller than the collection 1567 // did not succeed (e.g., because it was locked out by the GC 1568 // locker). So, right now, we'll ignore the return value. 1569 bool dummy = do_collection(true, /* explicit_gc */ 1570 clear_all_soft_refs, 1571 0 /* word_size */); 1572 } 1573 1574 // This code is mostly copied from TenuredGeneration. 1575 void 1576 G1CollectedHeap:: 1577 resize_if_necessary_after_full_collection(size_t word_size) { 1578 // Include the current allocation, if any, and bytes that will be 1579 // pre-allocated to support collections, as "used". 1580 const size_t used_after_gc = used(); 1581 const size_t capacity_after_gc = capacity(); 1582 const size_t free_after_gc = capacity_after_gc - used_after_gc; 1583 1584 // This is enforced in arguments.cpp. 1585 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, 1586 "otherwise the code below doesn't make sense"); 1587 1588 // We don't have floating point command-line arguments 1589 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0; 1590 const double maximum_used_percentage = 1.0 - minimum_free_percentage; 1591 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0; 1592 const double minimum_used_percentage = 1.0 - maximum_free_percentage; 1593 1594 const size_t min_heap_size = collector_policy()->min_heap_byte_size(); 1595 const size_t max_heap_size = collector_policy()->max_heap_byte_size(); 1596 1597 // We have to be careful here as these two calculations can overflow 1598 // 32-bit size_t's. 1599 double used_after_gc_d = (double) used_after_gc; 1600 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage; 1601 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage; 1602 1603 // Let's make sure that they are both under the max heap size, which 1604 // by default will make them fit into a size_t. 1605 double desired_capacity_upper_bound = (double) max_heap_size; 1606 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d, 1607 desired_capacity_upper_bound); 1608 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d, 1609 desired_capacity_upper_bound); 1610 1611 // We can now safely turn them into size_t's. 1612 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d; 1613 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d; 1614 1615 // This assert only makes sense here, before we adjust them 1616 // with respect to the min and max heap size. 1617 assert(minimum_desired_capacity <= maximum_desired_capacity, 1618 err_msg("minimum_desired_capacity = "SIZE_FORMAT", " 1619 "maximum_desired_capacity = "SIZE_FORMAT, 1620 minimum_desired_capacity, maximum_desired_capacity)); 1621 1622 // Should not be greater than the heap max size. No need to adjust 1623 // it with respect to the heap min size as it's a lower bound (i.e., 1624 // we'll try to make the capacity larger than it, not smaller). 1625 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size); 1626 // Should not be less than the heap min size. No need to adjust it 1627 // with respect to the heap max size as it's an upper bound (i.e., 1628 // we'll try to make the capacity smaller than it, not greater). 1629 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size); 1630 1631 if (capacity_after_gc < minimum_desired_capacity) { 1632 // Don't expand unless it's significant 1633 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc; 1634 ergo_verbose4(ErgoHeapSizing, 1635 "attempt heap expansion", 1636 ergo_format_reason("capacity lower than " 1637 "min desired capacity after Full GC") 1638 ergo_format_byte("capacity") 1639 ergo_format_byte("occupancy") 1640 ergo_format_byte_perc("min desired capacity"), 1641 capacity_after_gc, used_after_gc, 1642 minimum_desired_capacity, (double) MinHeapFreeRatio); 1643 expand(expand_bytes); 1644 1645 // No expansion, now see if we want to shrink 1646 } else if (capacity_after_gc > maximum_desired_capacity) { 1647 // Capacity too large, compute shrinking size 1648 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity; 1649 ergo_verbose4(ErgoHeapSizing, 1650 "attempt heap shrinking", 1651 ergo_format_reason("capacity higher than " 1652 "max desired capacity after Full GC") 1653 ergo_format_byte("capacity") 1654 ergo_format_byte("occupancy") 1655 ergo_format_byte_perc("max desired capacity"), 1656 capacity_after_gc, used_after_gc, 1657 maximum_desired_capacity, (double) MaxHeapFreeRatio); 1658 shrink(shrink_bytes); 1659 } 1660 } 1661 1662 1663 HeapWord* 1664 G1CollectedHeap::satisfy_failed_allocation(size_t word_size, 1665 bool* succeeded) { 1666 assert_at_safepoint(true /* should_be_vm_thread */); 1667 1668 *succeeded = true; 1669 // Let's attempt the allocation first. 1670 HeapWord* result = 1671 attempt_allocation_at_safepoint(word_size, 1672 false /* expect_null_mutator_alloc_region */); 1673 if (result != NULL) { 1674 assert(*succeeded, "sanity"); 1675 return result; 1676 } 1677 1678 // In a G1 heap, we're supposed to keep allocation from failing by 1679 // incremental pauses. Therefore, at least for now, we'll favor 1680 // expansion over collection. (This might change in the future if we can 1681 // do something smarter than full collection to satisfy a failed alloc.) 1682 result = expand_and_allocate(word_size); 1683 if (result != NULL) { 1684 assert(*succeeded, "sanity"); 1685 return result; 1686 } 1687 1688 // Expansion didn't work, we'll try to do a Full GC. 1689 bool gc_succeeded = do_collection(false, /* explicit_gc */ 1690 false, /* clear_all_soft_refs */ 1691 word_size); 1692 if (!gc_succeeded) { 1693 *succeeded = false; 1694 return NULL; 1695 } 1696 1697 // Retry the allocation 1698 result = attempt_allocation_at_safepoint(word_size, 1699 true /* expect_null_mutator_alloc_region */); 1700 if (result != NULL) { 1701 assert(*succeeded, "sanity"); 1702 return result; 1703 } 1704 1705 // Then, try a Full GC that will collect all soft references. 1706 gc_succeeded = do_collection(false, /* explicit_gc */ 1707 true, /* clear_all_soft_refs */ 1708 word_size); 1709 if (!gc_succeeded) { 1710 *succeeded = false; 1711 return NULL; 1712 } 1713 1714 // Retry the allocation once more 1715 result = attempt_allocation_at_safepoint(word_size, 1716 true /* expect_null_mutator_alloc_region */); 1717 if (result != NULL) { 1718 assert(*succeeded, "sanity"); 1719 return result; 1720 } 1721 1722 assert(!collector_policy()->should_clear_all_soft_refs(), 1723 "Flag should have been handled and cleared prior to this point"); 1724 1725 // What else? We might try synchronous finalization later. If the total 1726 // space available is large enough for the allocation, then a more 1727 // complete compaction phase than we've tried so far might be 1728 // appropriate. 1729 assert(*succeeded, "sanity"); 1730 return NULL; 1731 } 1732 1733 // Attempting to expand the heap sufficiently 1734 // to support an allocation of the given "word_size". If 1735 // successful, perform the allocation and return the address of the 1736 // allocated block, or else "NULL". 1737 1738 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) { 1739 assert_at_safepoint(true /* should_be_vm_thread */); 1740 1741 verify_region_sets_optional(); 1742 1743 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes); 1744 ergo_verbose1(ErgoHeapSizing, 1745 "attempt heap expansion", 1746 ergo_format_reason("allocation request failed") 1747 ergo_format_byte("allocation request"), 1748 word_size * HeapWordSize); 1749 if (expand(expand_bytes)) { 1750 _hrs.verify_optional(); 1751 verify_region_sets_optional(); 1752 return attempt_allocation_at_safepoint(word_size, 1753 false /* expect_null_mutator_alloc_region */); 1754 } 1755 return NULL; 1756 } 1757 1758 void G1CollectedHeap::update_committed_space(HeapWord* old_end, 1759 HeapWord* new_end) { 1760 assert(old_end != new_end, "don't call this otherwise"); 1761 assert((HeapWord*) _g1_storage.high() == new_end, "invariant"); 1762 1763 // Update the committed mem region. 1764 _g1_committed.set_end(new_end); 1765 // Tell the card table about the update. 1766 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed); 1767 // Tell the BOT about the update. 1768 _bot_shared->resize(_g1_committed.word_size()); 1769 // Tell the hot card cache about the update 1770 _cg1r->hot_card_cache()->resize_card_counts(capacity()); 1771 } 1772 1773 bool G1CollectedHeap::expand(size_t expand_bytes) { 1774 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); 1775 aligned_expand_bytes = align_size_up(aligned_expand_bytes, 1776 HeapRegion::GrainBytes); 1777 ergo_verbose2(ErgoHeapSizing, 1778 "expand the heap", 1779 ergo_format_byte("requested expansion amount") 1780 ergo_format_byte("attempted expansion amount"), 1781 expand_bytes, aligned_expand_bytes); 1782 1783 if (_g1_storage.uncommitted_size() == 0) { 1784 ergo_verbose0(ErgoHeapSizing, 1785 "did not expand the heap", 1786 ergo_format_reason("heap already fully expanded")); 1787 return false; 1788 } 1789 1790 // First commit the memory. 1791 HeapWord* old_end = (HeapWord*) _g1_storage.high(); 1792 bool successful = _g1_storage.expand_by(aligned_expand_bytes); 1793 if (successful) { 1794 // Then propagate this update to the necessary data structures. 1795 HeapWord* new_end = (HeapWord*) _g1_storage.high(); 1796 update_committed_space(old_end, new_end); 1797 1798 FreeRegionList expansion_list("Local Expansion List"); 1799 MemRegion mr = _hrs.expand_by(old_end, new_end, &expansion_list); 1800 assert(mr.start() == old_end, "post-condition"); 1801 // mr might be a smaller region than what was requested if 1802 // expand_by() was unable to allocate the HeapRegion instances 1803 assert(mr.end() <= new_end, "post-condition"); 1804 1805 size_t actual_expand_bytes = mr.byte_size(); 1806 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition"); 1807 assert(actual_expand_bytes == expansion_list.total_capacity_bytes(), 1808 "post-condition"); 1809 if (actual_expand_bytes < aligned_expand_bytes) { 1810 // We could not expand _hrs to the desired size. In this case we 1811 // need to shrink the committed space accordingly. 1812 assert(mr.end() < new_end, "invariant"); 1813 1814 size_t diff_bytes = aligned_expand_bytes - actual_expand_bytes; 1815 // First uncommit the memory. 1816 _g1_storage.shrink_by(diff_bytes); 1817 // Then propagate this update to the necessary data structures. 1818 update_committed_space(new_end, mr.end()); 1819 } 1820 _free_list.add_as_tail(&expansion_list); 1821 1822 if (_hr_printer.is_active()) { 1823 HeapWord* curr = mr.start(); 1824 while (curr < mr.end()) { 1825 HeapWord* curr_end = curr + HeapRegion::GrainWords; 1826 _hr_printer.commit(curr, curr_end); 1827 curr = curr_end; 1828 } 1829 assert(curr == mr.end(), "post-condition"); 1830 } 1831 g1_policy()->record_new_heap_size(n_regions()); 1832 } else { 1833 ergo_verbose0(ErgoHeapSizing, 1834 "did not expand the heap", 1835 ergo_format_reason("heap expansion operation failed")); 1836 // The expansion of the virtual storage space was unsuccessful. 1837 // Let's see if it was because we ran out of swap. 1838 if (G1ExitOnExpansionFailure && 1839 _g1_storage.uncommitted_size() >= aligned_expand_bytes) { 1840 // We had head room... 1841 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion"); 1842 } 1843 } 1844 return successful; 1845 } 1846 1847 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) { 1848 size_t aligned_shrink_bytes = 1849 ReservedSpace::page_align_size_down(shrink_bytes); 1850 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes, 1851 HeapRegion::GrainBytes); 1852 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes); 1853 1854 uint num_regions_removed = _hrs.shrink_by(num_regions_to_remove); 1855 HeapWord* old_end = (HeapWord*) _g1_storage.high(); 1856 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes; 1857 1858 ergo_verbose3(ErgoHeapSizing, 1859 "shrink the heap", 1860 ergo_format_byte("requested shrinking amount") 1861 ergo_format_byte("aligned shrinking amount") 1862 ergo_format_byte("attempted shrinking amount"), 1863 shrink_bytes, aligned_shrink_bytes, shrunk_bytes); 1864 if (num_regions_removed > 0) { 1865 _g1_storage.shrink_by(shrunk_bytes); 1866 HeapWord* new_end = (HeapWord*) _g1_storage.high(); 1867 1868 if (_hr_printer.is_active()) { 1869 HeapWord* curr = old_end; 1870 while (curr > new_end) { 1871 HeapWord* curr_end = curr; 1872 curr -= HeapRegion::GrainWords; 1873 _hr_printer.uncommit(curr, curr_end); 1874 } 1875 } 1876 1877 _expansion_regions += num_regions_removed; 1878 update_committed_space(old_end, new_end); 1879 HeapRegionRemSet::shrink_heap(n_regions()); 1880 g1_policy()->record_new_heap_size(n_regions()); 1881 } else { 1882 ergo_verbose0(ErgoHeapSizing, 1883 "did not shrink the heap", 1884 ergo_format_reason("heap shrinking operation failed")); 1885 } 1886 } 1887 1888 void G1CollectedHeap::shrink(size_t shrink_bytes) { 1889 verify_region_sets_optional(); 1890 1891 // We should only reach here at the end of a Full GC which means we 1892 // should not not be holding to any GC alloc regions. The method 1893 // below will make sure of that and do any remaining clean up. 1894 abandon_gc_alloc_regions(); 1895 1896 // Instead of tearing down / rebuilding the free lists here, we 1897 // could instead use the remove_all_pending() method on free_list to 1898 // remove only the ones that we need to remove. 1899 tear_down_region_sets(true /* free_list_only */); 1900 shrink_helper(shrink_bytes); 1901 rebuild_region_sets(true /* free_list_only */); 1902 1903 _hrs.verify_optional(); 1904 verify_region_sets_optional(); 1905 } 1906 1907 // Public methods. 1908 1909 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away 1910 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list 1911 #endif // _MSC_VER 1912 1913 1914 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) : 1915 SharedHeap(policy_), 1916 _g1_policy(policy_), 1917 _dirty_card_queue_set(false), 1918 _into_cset_dirty_card_queue_set(false), 1919 _is_alive_closure_cm(this), 1920 _is_alive_closure_stw(this), 1921 _ref_processor_cm(NULL), 1922 _ref_processor_stw(NULL), 1923 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)), 1924 _bot_shared(NULL), 1925 _evac_failure_scan_stack(NULL), 1926 _mark_in_progress(false), 1927 _cg1r(NULL), _summary_bytes_used(0), 1928 _g1mm(NULL), 1929 _refine_cte_cl(NULL), 1930 _full_collection(false), 1931 _free_list("Master Free List"), 1932 _secondary_free_list("Secondary Free List"), 1933 _old_set("Old Set"), 1934 _humongous_set("Master Humongous Set"), 1935 _free_regions_coming(false), 1936 _young_list(new YoungList(this)), 1937 _gc_time_stamp(0), 1938 _retained_old_gc_alloc_region(NULL), 1939 _survivor_plab_stats(YoungPLABSize, PLABWeight), 1940 _old_plab_stats(OldPLABSize, PLABWeight), 1941 _expand_heap_after_alloc_failure(true), 1942 _surviving_young_words(NULL), 1943 _old_marking_cycles_started(0), 1944 _old_marking_cycles_completed(0), 1945 _concurrent_cycle_started(false), 1946 _in_cset_fast_test(NULL), 1947 _in_cset_fast_test_base(NULL), 1948 _dirty_cards_region_list(NULL), 1949 _worker_cset_start_region(NULL), 1950 _worker_cset_start_region_time_stamp(NULL), 1951 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()), 1952 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()), 1953 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()), 1954 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) { 1955 1956 _g1h = this; 1957 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) { 1958 vm_exit_during_initialization("Failed necessary allocation."); 1959 } 1960 1961 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2; 1962 1963 int n_queues = MAX2((int)ParallelGCThreads, 1); 1964 _task_queues = new RefToScanQueueSet(n_queues); 1965 1966 int n_rem_sets = HeapRegionRemSet::num_par_rem_sets(); 1967 assert(n_rem_sets > 0, "Invariant."); 1968 1969 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC); 1970 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(unsigned int, n_queues, mtGC); 1971 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC); 1972 1973 for (int i = 0; i < n_queues; i++) { 1974 RefToScanQueue* q = new RefToScanQueue(); 1975 q->initialize(); 1976 _task_queues->register_queue(i, q); 1977 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo(); 1978 } 1979 clear_cset_start_regions(); 1980 1981 // Initialize the G1EvacuationFailureALot counters and flags. 1982 NOT_PRODUCT(reset_evacuation_should_fail();) 1983 1984 guarantee(_task_queues != NULL, "task_queues allocation failure."); 1985 } 1986 1987 jint G1CollectedHeap::initialize() { 1988 CollectedHeap::pre_initialize(); 1989 os::enable_vtime(); 1990 1991 G1Log::init(); 1992 1993 // Necessary to satisfy locking discipline assertions. 1994 1995 MutexLocker x(Heap_lock); 1996 1997 // We have to initialize the printer before committing the heap, as 1998 // it will be used then. 1999 _hr_printer.set_active(G1PrintHeapRegions); 2000 2001 // While there are no constraints in the GC code that HeapWordSize 2002 // be any particular value, there are multiple other areas in the 2003 // system which believe this to be true (e.g. oop->object_size in some 2004 // cases incorrectly returns the size in wordSize units rather than 2005 // HeapWordSize). 2006 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 2007 2008 size_t init_byte_size = collector_policy()->initial_heap_byte_size(); 2009 size_t max_byte_size = collector_policy()->max_heap_byte_size(); 2010 size_t heap_alignment = collector_policy()->heap_alignment(); 2011 2012 // Ensure that the sizes are properly aligned. 2013 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap"); 2014 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap"); 2015 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap"); 2016 2017 _cg1r = new ConcurrentG1Refine(this); 2018 2019 // Reserve the maximum. 2020 2021 // When compressed oops are enabled, the preferred heap base 2022 // is calculated by subtracting the requested size from the 2023 // 32Gb boundary and using the result as the base address for 2024 // heap reservation. If the requested size is not aligned to 2025 // HeapRegion::GrainBytes (i.e. the alignment that is passed 2026 // into the ReservedHeapSpace constructor) then the actual 2027 // base of the reserved heap may end up differing from the 2028 // address that was requested (i.e. the preferred heap base). 2029 // If this happens then we could end up using a non-optimal 2030 // compressed oops mode. 2031 2032 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size, 2033 heap_alignment); 2034 2035 // It is important to do this in a way such that concurrent readers can't 2036 // temporarily think something is in the heap. (I've actually seen this 2037 // happen in asserts: DLD.) 2038 _reserved.set_word_size(0); 2039 _reserved.set_start((HeapWord*)heap_rs.base()); 2040 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size())); 2041 2042 _expansion_regions = (uint) (max_byte_size / HeapRegion::GrainBytes); 2043 2044 // Create the gen rem set (and barrier set) for the entire reserved region. 2045 _rem_set = collector_policy()->create_rem_set(_reserved, 2); 2046 set_barrier_set(rem_set()->bs()); 2047 if (!barrier_set()->is_a(BarrierSet::G1SATBCTLogging)) { 2048 vm_exit_during_initialization("G1 requires a G1SATBLoggingCardTableModRefBS"); 2049 return JNI_ENOMEM; 2050 } 2051 2052 // Also create a G1 rem set. 2053 _g1_rem_set = new G1RemSet(this, g1_barrier_set()); 2054 2055 // Carve out the G1 part of the heap. 2056 2057 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size); 2058 _g1_reserved = MemRegion((HeapWord*)g1_rs.base(), 2059 g1_rs.size()/HeapWordSize); 2060 2061 _g1_storage.initialize(g1_rs, 0); 2062 _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0); 2063 _hrs.initialize((HeapWord*) _g1_reserved.start(), 2064 (HeapWord*) _g1_reserved.end()); 2065 assert(_hrs.max_length() == _expansion_regions, 2066 err_msg("max length: %u expansion regions: %u", 2067 _hrs.max_length(), _expansion_regions)); 2068 2069 // Do later initialization work for concurrent refinement. 2070 _cg1r->init(); 2071 2072 // 6843694 - ensure that the maximum region index can fit 2073 // in the remembered set structures. 2074 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; 2075 guarantee((max_regions() - 1) <= max_region_idx, "too many regions"); 2076 2077 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; 2078 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); 2079 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region, 2080 "too many cards per region"); 2081 2082 HeapRegionSet::set_unrealistically_long_length(max_regions() + 1); 2083 2084 _bot_shared = new G1BlockOffsetSharedArray(_reserved, 2085 heap_word_size(init_byte_size)); 2086 2087 _g1h = this; 2088 2089 _in_cset_fast_test_length = max_regions(); 2090 _in_cset_fast_test_base = 2091 NEW_C_HEAP_ARRAY(bool, (size_t) _in_cset_fast_test_length, mtGC); 2092 2093 // We're biasing _in_cset_fast_test to avoid subtracting the 2094 // beginning of the heap every time we want to index; basically 2095 // it's the same with what we do with the card table. 2096 _in_cset_fast_test = _in_cset_fast_test_base - 2097 ((uintx) _g1_reserved.start() >> HeapRegion::LogOfHRGrainBytes); 2098 2099 // Clear the _cset_fast_test bitmap in anticipation of adding 2100 // regions to the incremental collection set for the first 2101 // evacuation pause. 2102 clear_cset_fast_test(); 2103 2104 // Create the ConcurrentMark data structure and thread. 2105 // (Must do this late, so that "max_regions" is defined.) 2106 _cm = new ConcurrentMark(this, heap_rs); 2107 if (_cm == NULL || !_cm->completed_initialization()) { 2108 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark"); 2109 return JNI_ENOMEM; 2110 } 2111 _cmThread = _cm->cmThread(); 2112 2113 // Initialize the from_card cache structure of HeapRegionRemSet. 2114 HeapRegionRemSet::init_heap(max_regions()); 2115 2116 // Now expand into the initial heap size. 2117 if (!expand(init_byte_size)) { 2118 vm_shutdown_during_initialization("Failed to allocate initial heap."); 2119 return JNI_ENOMEM; 2120 } 2121 2122 // Perform any initialization actions delegated to the policy. 2123 g1_policy()->init(); 2124 2125 _refine_cte_cl = 2126 new RefineCardTableEntryClosure(ConcurrentG1RefineThread::sts(), 2127 g1_rem_set(), 2128 concurrent_g1_refine()); 2129 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl); 2130 2131 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon, 2132 SATB_Q_FL_lock, 2133 G1SATBProcessCompletedThreshold, 2134 Shared_SATB_Q_lock); 2135 2136 JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon, 2137 DirtyCardQ_FL_lock, 2138 concurrent_g1_refine()->yellow_zone(), 2139 concurrent_g1_refine()->red_zone(), 2140 Shared_DirtyCardQ_lock); 2141 2142 if (G1DeferredRSUpdate) { 2143 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon, 2144 DirtyCardQ_FL_lock, 2145 -1, // never trigger processing 2146 -1, // no limit on length 2147 Shared_DirtyCardQ_lock, 2148 &JavaThread::dirty_card_queue_set()); 2149 } 2150 2151 // Initialize the card queue set used to hold cards containing 2152 // references into the collection set. 2153 _into_cset_dirty_card_queue_set.initialize(DirtyCardQ_CBL_mon, 2154 DirtyCardQ_FL_lock, 2155 -1, // never trigger processing 2156 -1, // no limit on length 2157 Shared_DirtyCardQ_lock, 2158 &JavaThread::dirty_card_queue_set()); 2159 2160 // In case we're keeping closure specialization stats, initialize those 2161 // counts and that mechanism. 2162 SpecializationStats::clear(); 2163 2164 // Here we allocate the dummy full region that is required by the 2165 // G1AllocRegion class. If we don't pass an address in the reserved 2166 // space here, lots of asserts fire. 2167 2168 HeapRegion* dummy_region = new_heap_region(0 /* index of bottom region */, 2169 _g1_reserved.start()); 2170 // We'll re-use the same region whether the alloc region will 2171 // require BOT updates or not and, if it doesn't, then a non-young 2172 // region will complain that it cannot support allocations without 2173 // BOT updates. So we'll tag the dummy region as young to avoid that. 2174 dummy_region->set_young(); 2175 // Make sure it's full. 2176 dummy_region->set_top(dummy_region->end()); 2177 G1AllocRegion::setup(this, dummy_region); 2178 2179 init_mutator_alloc_region(); 2180 2181 // Do create of the monitoring and management support so that 2182 // values in the heap have been properly initialized. 2183 _g1mm = new G1MonitoringSupport(this); 2184 2185 return JNI_OK; 2186 } 2187 2188 size_t G1CollectedHeap::conservative_max_heap_alignment() { 2189 return HeapRegion::max_region_size(); 2190 } 2191 2192 void G1CollectedHeap::ref_processing_init() { 2193 // Reference processing in G1 currently works as follows: 2194 // 2195 // * There are two reference processor instances. One is 2196 // used to record and process discovered references 2197 // during concurrent marking; the other is used to 2198 // record and process references during STW pauses 2199 // (both full and incremental). 2200 // * Both ref processors need to 'span' the entire heap as 2201 // the regions in the collection set may be dotted around. 2202 // 2203 // * For the concurrent marking ref processor: 2204 // * Reference discovery is enabled at initial marking. 2205 // * Reference discovery is disabled and the discovered 2206 // references processed etc during remarking. 2207 // * Reference discovery is MT (see below). 2208 // * Reference discovery requires a barrier (see below). 2209 // * Reference processing may or may not be MT 2210 // (depending on the value of ParallelRefProcEnabled 2211 // and ParallelGCThreads). 2212 // * A full GC disables reference discovery by the CM 2213 // ref processor and abandons any entries on it's 2214 // discovered lists. 2215 // 2216 // * For the STW processor: 2217 // * Non MT discovery is enabled at the start of a full GC. 2218 // * Processing and enqueueing during a full GC is non-MT. 2219 // * During a full GC, references are processed after marking. 2220 // 2221 // * Discovery (may or may not be MT) is enabled at the start 2222 // of an incremental evacuation pause. 2223 // * References are processed near the end of a STW evacuation pause. 2224 // * For both types of GC: 2225 // * Discovery is atomic - i.e. not concurrent. 2226 // * Reference discovery will not need a barrier. 2227 2228 SharedHeap::ref_processing_init(); 2229 MemRegion mr = reserved_region(); 2230 2231 // Concurrent Mark ref processor 2232 _ref_processor_cm = 2233 new ReferenceProcessor(mr, // span 2234 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2235 // mt processing 2236 (int) ParallelGCThreads, 2237 // degree of mt processing 2238 (ParallelGCThreads > 1) || (ConcGCThreads > 1), 2239 // mt discovery 2240 (int) MAX2(ParallelGCThreads, ConcGCThreads), 2241 // degree of mt discovery 2242 false, 2243 // Reference discovery is not atomic 2244 &_is_alive_closure_cm, 2245 // is alive closure 2246 // (for efficiency/performance) 2247 true); 2248 // Setting next fields of discovered 2249 // lists requires a barrier. 2250 2251 // STW ref processor 2252 _ref_processor_stw = 2253 new ReferenceProcessor(mr, // span 2254 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2255 // mt processing 2256 MAX2((int)ParallelGCThreads, 1), 2257 // degree of mt processing 2258 (ParallelGCThreads > 1), 2259 // mt discovery 2260 MAX2((int)ParallelGCThreads, 1), 2261 // degree of mt discovery 2262 true, 2263 // Reference discovery is atomic 2264 &_is_alive_closure_stw, 2265 // is alive closure 2266 // (for efficiency/performance) 2267 false); 2268 // Setting next fields of discovered 2269 // lists does not require a barrier. 2270 } 2271 2272 size_t G1CollectedHeap::capacity() const { 2273 return _g1_committed.byte_size(); 2274 } 2275 2276 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) { 2277 assert(!hr->continuesHumongous(), "pre-condition"); 2278 hr->reset_gc_time_stamp(); 2279 if (hr->startsHumongous()) { 2280 uint first_index = hr->hrs_index() + 1; 2281 uint last_index = hr->last_hc_index(); 2282 for (uint i = first_index; i < last_index; i += 1) { 2283 HeapRegion* chr = region_at(i); 2284 assert(chr->continuesHumongous(), "sanity"); 2285 chr->reset_gc_time_stamp(); 2286 } 2287 } 2288 } 2289 2290 #ifndef PRODUCT 2291 class CheckGCTimeStampsHRClosure : public HeapRegionClosure { 2292 private: 2293 unsigned _gc_time_stamp; 2294 bool _failures; 2295 2296 public: 2297 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) : 2298 _gc_time_stamp(gc_time_stamp), _failures(false) { } 2299 2300 virtual bool doHeapRegion(HeapRegion* hr) { 2301 unsigned region_gc_time_stamp = hr->get_gc_time_stamp(); 2302 if (_gc_time_stamp != region_gc_time_stamp) { 2303 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, " 2304 "expected %d", HR_FORMAT_PARAMS(hr), 2305 region_gc_time_stamp, _gc_time_stamp); 2306 _failures = true; 2307 } 2308 return false; 2309 } 2310 2311 bool failures() { return _failures; } 2312 }; 2313 2314 void G1CollectedHeap::check_gc_time_stamps() { 2315 CheckGCTimeStampsHRClosure cl(_gc_time_stamp); 2316 heap_region_iterate(&cl); 2317 guarantee(!cl.failures(), "all GC time stamps should have been reset"); 2318 } 2319 #endif // PRODUCT 2320 2321 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, 2322 DirtyCardQueue* into_cset_dcq, 2323 bool concurrent, 2324 int worker_i) { 2325 // Clean cards in the hot card cache 2326 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 2327 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq); 2328 2329 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 2330 int n_completed_buffers = 0; 2331 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) { 2332 n_completed_buffers++; 2333 } 2334 g1_policy()->phase_times()->record_update_rs_processed_buffers(worker_i, n_completed_buffers); 2335 dcqs.clear_n_completed_buffers(); 2336 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!"); 2337 } 2338 2339 2340 // Computes the sum of the storage used by the various regions. 2341 2342 size_t G1CollectedHeap::used() const { 2343 assert(Heap_lock->owner() != NULL, 2344 "Should be owned on this thread's behalf."); 2345 size_t result = _summary_bytes_used; 2346 // Read only once in case it is set to NULL concurrently 2347 HeapRegion* hr = _mutator_alloc_region.get(); 2348 if (hr != NULL) 2349 result += hr->used(); 2350 return result; 2351 } 2352 2353 size_t G1CollectedHeap::used_unlocked() const { 2354 size_t result = _summary_bytes_used; 2355 return result; 2356 } 2357 2358 class SumUsedClosure: public HeapRegionClosure { 2359 size_t _used; 2360 public: 2361 SumUsedClosure() : _used(0) {} 2362 bool doHeapRegion(HeapRegion* r) { 2363 if (!r->continuesHumongous()) { 2364 _used += r->used(); 2365 } 2366 return false; 2367 } 2368 size_t result() { return _used; } 2369 }; 2370 2371 size_t G1CollectedHeap::recalculate_used() const { 2372 SumUsedClosure blk; 2373 heap_region_iterate(&blk); 2374 return blk.result(); 2375 } 2376 2377 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 2378 switch (cause) { 2379 case GCCause::_gc_locker: return GCLockerInvokesConcurrent; 2380 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent; 2381 case GCCause::_g1_humongous_allocation: return true; 2382 default: return false; 2383 } 2384 } 2385 2386 #ifndef PRODUCT 2387 void G1CollectedHeap::allocate_dummy_regions() { 2388 // Let's fill up most of the region 2389 size_t word_size = HeapRegion::GrainWords - 1024; 2390 // And as a result the region we'll allocate will be humongous. 2391 guarantee(isHumongous(word_size), "sanity"); 2392 2393 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) { 2394 // Let's use the existing mechanism for the allocation 2395 HeapWord* dummy_obj = humongous_obj_allocate(word_size); 2396 if (dummy_obj != NULL) { 2397 MemRegion mr(dummy_obj, word_size); 2398 CollectedHeap::fill_with_object(mr); 2399 } else { 2400 // If we can't allocate once, we probably cannot allocate 2401 // again. Let's get out of the loop. 2402 break; 2403 } 2404 } 2405 } 2406 #endif // !PRODUCT 2407 2408 void G1CollectedHeap::increment_old_marking_cycles_started() { 2409 assert(_old_marking_cycles_started == _old_marking_cycles_completed || 2410 _old_marking_cycles_started == _old_marking_cycles_completed + 1, 2411 err_msg("Wrong marking cycle count (started: %d, completed: %d)", 2412 _old_marking_cycles_started, _old_marking_cycles_completed)); 2413 2414 _old_marking_cycles_started++; 2415 } 2416 2417 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) { 2418 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 2419 2420 // We assume that if concurrent == true, then the caller is a 2421 // concurrent thread that was joined the Suspendible Thread 2422 // Set. If there's ever a cheap way to check this, we should add an 2423 // assert here. 2424 2425 // Given that this method is called at the end of a Full GC or of a 2426 // concurrent cycle, and those can be nested (i.e., a Full GC can 2427 // interrupt a concurrent cycle), the number of full collections 2428 // completed should be either one (in the case where there was no 2429 // nesting) or two (when a Full GC interrupted a concurrent cycle) 2430 // behind the number of full collections started. 2431 2432 // This is the case for the inner caller, i.e. a Full GC. 2433 assert(concurrent || 2434 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || 2435 (_old_marking_cycles_started == _old_marking_cycles_completed + 2), 2436 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u " 2437 "is inconsistent with _old_marking_cycles_completed = %u", 2438 _old_marking_cycles_started, _old_marking_cycles_completed)); 2439 2440 // This is the case for the outer caller, i.e. the concurrent cycle. 2441 assert(!concurrent || 2442 (_old_marking_cycles_started == _old_marking_cycles_completed + 1), 2443 err_msg("for outer caller (concurrent cycle): " 2444 "_old_marking_cycles_started = %u " 2445 "is inconsistent with _old_marking_cycles_completed = %u", 2446 _old_marking_cycles_started, _old_marking_cycles_completed)); 2447 2448 _old_marking_cycles_completed += 1; 2449 2450 // We need to clear the "in_progress" flag in the CM thread before 2451 // we wake up any waiters (especially when ExplicitInvokesConcurrent 2452 // is set) so that if a waiter requests another System.gc() it doesn't 2453 // incorrectly see that a marking cycle is still in progress. 2454 if (concurrent) { 2455 _cmThread->clear_in_progress(); 2456 } 2457 2458 // This notify_all() will ensure that a thread that called 2459 // System.gc() with (with ExplicitGCInvokesConcurrent set or not) 2460 // and it's waiting for a full GC to finish will be woken up. It is 2461 // waiting in VM_G1IncCollectionPause::doit_epilogue(). 2462 FullGCCount_lock->notify_all(); 2463 } 2464 2465 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) { 2466 _concurrent_cycle_started = true; 2467 _gc_timer_cm->register_gc_start(start_time); 2468 2469 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start()); 2470 trace_heap_before_gc(_gc_tracer_cm); 2471 } 2472 2473 void G1CollectedHeap::register_concurrent_cycle_end() { 2474 if (_concurrent_cycle_started) { 2475 if (_cm->has_aborted()) { 2476 _gc_tracer_cm->report_concurrent_mode_failure(); 2477 } 2478 2479 _gc_timer_cm->register_gc_end(); 2480 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions()); 2481 2482 _concurrent_cycle_started = false; 2483 } 2484 } 2485 2486 void G1CollectedHeap::trace_heap_after_concurrent_cycle() { 2487 if (_concurrent_cycle_started) { 2488 trace_heap_after_gc(_gc_tracer_cm); 2489 } 2490 } 2491 2492 G1YCType G1CollectedHeap::yc_type() { 2493 bool is_young = g1_policy()->gcs_are_young(); 2494 bool is_initial_mark = g1_policy()->during_initial_mark_pause(); 2495 bool is_during_mark = mark_in_progress(); 2496 2497 if (is_initial_mark) { 2498 return InitialMark; 2499 } else if (is_during_mark) { 2500 return DuringMark; 2501 } else if (is_young) { 2502 return Normal; 2503 } else { 2504 return Mixed; 2505 } 2506 } 2507 2508 void G1CollectedHeap::collect(GCCause::Cause cause) { 2509 assert_heap_not_locked(); 2510 2511 unsigned int gc_count_before; 2512 unsigned int old_marking_count_before; 2513 bool retry_gc; 2514 2515 do { 2516 retry_gc = false; 2517 2518 { 2519 MutexLocker ml(Heap_lock); 2520 2521 // Read the GC count while holding the Heap_lock 2522 gc_count_before = total_collections(); 2523 old_marking_count_before = _old_marking_cycles_started; 2524 } 2525 2526 if (should_do_concurrent_full_gc(cause)) { 2527 // Schedule an initial-mark evacuation pause that will start a 2528 // concurrent cycle. We're setting word_size to 0 which means that 2529 // we are not requesting a post-GC allocation. 2530 VM_G1IncCollectionPause op(gc_count_before, 2531 0, /* word_size */ 2532 true, /* should_initiate_conc_mark */ 2533 g1_policy()->max_pause_time_ms(), 2534 cause); 2535 2536 VMThread::execute(&op); 2537 if (!op.pause_succeeded()) { 2538 if (old_marking_count_before == _old_marking_cycles_started) { 2539 retry_gc = op.should_retry_gc(); 2540 } else { 2541 // A Full GC happened while we were trying to schedule the 2542 // initial-mark GC. No point in starting a new cycle given 2543 // that the whole heap was collected anyway. 2544 } 2545 2546 if (retry_gc) { 2547 if (GC_locker::is_active_and_needs_gc()) { 2548 GC_locker::stall_until_clear(); 2549 } 2550 } 2551 } 2552 } else { 2553 if (cause == GCCause::_gc_locker 2554 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { 2555 2556 // Schedule a standard evacuation pause. We're setting word_size 2557 // to 0 which means that we are not requesting a post-GC allocation. 2558 VM_G1IncCollectionPause op(gc_count_before, 2559 0, /* word_size */ 2560 false, /* should_initiate_conc_mark */ 2561 g1_policy()->max_pause_time_ms(), 2562 cause); 2563 VMThread::execute(&op); 2564 } else { 2565 // Schedule a Full GC. 2566 VM_G1CollectFull op(gc_count_before, old_marking_count_before, cause); 2567 VMThread::execute(&op); 2568 } 2569 } 2570 } while (retry_gc); 2571 } 2572 2573 bool G1CollectedHeap::is_in(const void* p) const { 2574 if (_g1_committed.contains(p)) { 2575 // Given that we know that p is in the committed space, 2576 // heap_region_containing_raw() should successfully 2577 // return the containing region. 2578 HeapRegion* hr = heap_region_containing_raw(p); 2579 return hr->is_in(p); 2580 } else { 2581 return false; 2582 } 2583 } 2584 2585 // Iteration functions. 2586 2587 // Iterates an OopClosure over all ref-containing fields of objects 2588 // within a HeapRegion. 2589 2590 class IterateOopClosureRegionClosure: public HeapRegionClosure { 2591 MemRegion _mr; 2592 ExtendedOopClosure* _cl; 2593 public: 2594 IterateOopClosureRegionClosure(MemRegion mr, ExtendedOopClosure* cl) 2595 : _mr(mr), _cl(cl) {} 2596 bool doHeapRegion(HeapRegion* r) { 2597 if (!r->continuesHumongous()) { 2598 r->oop_iterate(_cl); 2599 } 2600 return false; 2601 } 2602 }; 2603 2604 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) { 2605 IterateOopClosureRegionClosure blk(_g1_committed, cl); 2606 heap_region_iterate(&blk); 2607 } 2608 2609 void G1CollectedHeap::oop_iterate(MemRegion mr, ExtendedOopClosure* cl) { 2610 IterateOopClosureRegionClosure blk(mr, cl); 2611 heap_region_iterate(&blk); 2612 } 2613 2614 // Iterates an ObjectClosure over all objects within a HeapRegion. 2615 2616 class IterateObjectClosureRegionClosure: public HeapRegionClosure { 2617 ObjectClosure* _cl; 2618 public: 2619 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} 2620 bool doHeapRegion(HeapRegion* r) { 2621 if (! r->continuesHumongous()) { 2622 r->object_iterate(_cl); 2623 } 2624 return false; 2625 } 2626 }; 2627 2628 void G1CollectedHeap::object_iterate(ObjectClosure* cl) { 2629 IterateObjectClosureRegionClosure blk(cl); 2630 heap_region_iterate(&blk); 2631 } 2632 2633 // Calls a SpaceClosure on a HeapRegion. 2634 2635 class SpaceClosureRegionClosure: public HeapRegionClosure { 2636 SpaceClosure* _cl; 2637 public: 2638 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {} 2639 bool doHeapRegion(HeapRegion* r) { 2640 _cl->do_space(r); 2641 return false; 2642 } 2643 }; 2644 2645 void G1CollectedHeap::space_iterate(SpaceClosure* cl) { 2646 SpaceClosureRegionClosure blk(cl); 2647 heap_region_iterate(&blk); 2648 } 2649 2650 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { 2651 _hrs.iterate(cl); 2652 } 2653 2654 void 2655 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl, 2656 uint worker_id, 2657 uint no_of_par_workers, 2658 jint claim_value) { 2659 const uint regions = n_regions(); 2660 const uint max_workers = (G1CollectedHeap::use_parallel_gc_threads() ? 2661 no_of_par_workers : 2662 1); 2663 assert(UseDynamicNumberOfGCThreads || 2664 no_of_par_workers == workers()->total_workers(), 2665 "Non dynamic should use fixed number of workers"); 2666 // try to spread out the starting points of the workers 2667 const HeapRegion* start_hr = 2668 start_region_for_worker(worker_id, no_of_par_workers); 2669 const uint start_index = start_hr->hrs_index(); 2670 2671 // each worker will actually look at all regions 2672 for (uint count = 0; count < regions; ++count) { 2673 const uint index = (start_index + count) % regions; 2674 assert(0 <= index && index < regions, "sanity"); 2675 HeapRegion* r = region_at(index); 2676 // we'll ignore "continues humongous" regions (we'll process them 2677 // when we come across their corresponding "start humongous" 2678 // region) and regions already claimed 2679 if (r->claim_value() == claim_value || r->continuesHumongous()) { 2680 continue; 2681 } 2682 // OK, try to claim it 2683 if (r->claimHeapRegion(claim_value)) { 2684 // success! 2685 assert(!r->continuesHumongous(), "sanity"); 2686 if (r->startsHumongous()) { 2687 // If the region is "starts humongous" we'll iterate over its 2688 // "continues humongous" first; in fact we'll do them 2689 // first. The order is important. In on case, calling the 2690 // closure on the "starts humongous" region might de-allocate 2691 // and clear all its "continues humongous" regions and, as a 2692 // result, we might end up processing them twice. So, we'll do 2693 // them first (notice: most closures will ignore them anyway) and 2694 // then we'll do the "starts humongous" region. 2695 for (uint ch_index = index + 1; ch_index < regions; ++ch_index) { 2696 HeapRegion* chr = region_at(ch_index); 2697 2698 // if the region has already been claimed or it's not 2699 // "continues humongous" we're done 2700 if (chr->claim_value() == claim_value || 2701 !chr->continuesHumongous()) { 2702 break; 2703 } 2704 2705 // No one should have claimed it directly. We can given 2706 // that we claimed its "starts humongous" region. 2707 assert(chr->claim_value() != claim_value, "sanity"); 2708 assert(chr->humongous_start_region() == r, "sanity"); 2709 2710 if (chr->claimHeapRegion(claim_value)) { 2711 // we should always be able to claim it; no one else should 2712 // be trying to claim this region 2713 2714 bool res2 = cl->doHeapRegion(chr); 2715 assert(!res2, "Should not abort"); 2716 2717 // Right now, this holds (i.e., no closure that actually 2718 // does something with "continues humongous" regions 2719 // clears them). We might have to weaken it in the future, 2720 // but let's leave these two asserts here for extra safety. 2721 assert(chr->continuesHumongous(), "should still be the case"); 2722 assert(chr->humongous_start_region() == r, "sanity"); 2723 } else { 2724 guarantee(false, "we should not reach here"); 2725 } 2726 } 2727 } 2728 2729 assert(!r->continuesHumongous(), "sanity"); 2730 bool res = cl->doHeapRegion(r); 2731 assert(!res, "Should not abort"); 2732 } 2733 } 2734 } 2735 2736 class ResetClaimValuesClosure: public HeapRegionClosure { 2737 public: 2738 bool doHeapRegion(HeapRegion* r) { 2739 r->set_claim_value(HeapRegion::InitialClaimValue); 2740 return false; 2741 } 2742 }; 2743 2744 void G1CollectedHeap::reset_heap_region_claim_values() { 2745 ResetClaimValuesClosure blk; 2746 heap_region_iterate(&blk); 2747 } 2748 2749 void G1CollectedHeap::reset_cset_heap_region_claim_values() { 2750 ResetClaimValuesClosure blk; 2751 collection_set_iterate(&blk); 2752 } 2753 2754 #ifdef ASSERT 2755 // This checks whether all regions in the heap have the correct claim 2756 // value. I also piggy-backed on this a check to ensure that the 2757 // humongous_start_region() information on "continues humongous" 2758 // regions is correct. 2759 2760 class CheckClaimValuesClosure : public HeapRegionClosure { 2761 private: 2762 jint _claim_value; 2763 uint _failures; 2764 HeapRegion* _sh_region; 2765 2766 public: 2767 CheckClaimValuesClosure(jint claim_value) : 2768 _claim_value(claim_value), _failures(0), _sh_region(NULL) { } 2769 bool doHeapRegion(HeapRegion* r) { 2770 if (r->claim_value() != _claim_value) { 2771 gclog_or_tty->print_cr("Region " HR_FORMAT ", " 2772 "claim value = %d, should be %d", 2773 HR_FORMAT_PARAMS(r), 2774 r->claim_value(), _claim_value); 2775 ++_failures; 2776 } 2777 if (!r->isHumongous()) { 2778 _sh_region = NULL; 2779 } else if (r->startsHumongous()) { 2780 _sh_region = r; 2781 } else if (r->continuesHumongous()) { 2782 if (r->humongous_start_region() != _sh_region) { 2783 gclog_or_tty->print_cr("Region " HR_FORMAT ", " 2784 "HS = "PTR_FORMAT", should be "PTR_FORMAT, 2785 HR_FORMAT_PARAMS(r), 2786 r->humongous_start_region(), 2787 _sh_region); 2788 ++_failures; 2789 } 2790 } 2791 return false; 2792 } 2793 uint failures() { return _failures; } 2794 }; 2795 2796 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) { 2797 CheckClaimValuesClosure cl(claim_value); 2798 heap_region_iterate(&cl); 2799 return cl.failures() == 0; 2800 } 2801 2802 class CheckClaimValuesInCSetHRClosure: public HeapRegionClosure { 2803 private: 2804 jint _claim_value; 2805 uint _failures; 2806 2807 public: 2808 CheckClaimValuesInCSetHRClosure(jint claim_value) : 2809 _claim_value(claim_value), _failures(0) { } 2810 2811 uint failures() { return _failures; } 2812 2813 bool doHeapRegion(HeapRegion* hr) { 2814 assert(hr->in_collection_set(), "how?"); 2815 assert(!hr->isHumongous(), "H-region in CSet"); 2816 if (hr->claim_value() != _claim_value) { 2817 gclog_or_tty->print_cr("CSet Region " HR_FORMAT ", " 2818 "claim value = %d, should be %d", 2819 HR_FORMAT_PARAMS(hr), 2820 hr->claim_value(), _claim_value); 2821 _failures += 1; 2822 } 2823 return false; 2824 } 2825 }; 2826 2827 bool G1CollectedHeap::check_cset_heap_region_claim_values(jint claim_value) { 2828 CheckClaimValuesInCSetHRClosure cl(claim_value); 2829 collection_set_iterate(&cl); 2830 return cl.failures() == 0; 2831 } 2832 #endif // ASSERT 2833 2834 // Clear the cached CSet starting regions and (more importantly) 2835 // the time stamps. Called when we reset the GC time stamp. 2836 void G1CollectedHeap::clear_cset_start_regions() { 2837 assert(_worker_cset_start_region != NULL, "sanity"); 2838 assert(_worker_cset_start_region_time_stamp != NULL, "sanity"); 2839 2840 int n_queues = MAX2((int)ParallelGCThreads, 1); 2841 for (int i = 0; i < n_queues; i++) { 2842 _worker_cset_start_region[i] = NULL; 2843 _worker_cset_start_region_time_stamp[i] = 0; 2844 } 2845 } 2846 2847 // Given the id of a worker, obtain or calculate a suitable 2848 // starting region for iterating over the current collection set. 2849 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(int worker_i) { 2850 assert(get_gc_time_stamp() > 0, "should have been updated by now"); 2851 2852 HeapRegion* result = NULL; 2853 unsigned gc_time_stamp = get_gc_time_stamp(); 2854 2855 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) { 2856 // Cached starting region for current worker was set 2857 // during the current pause - so it's valid. 2858 // Note: the cached starting heap region may be NULL 2859 // (when the collection set is empty). 2860 result = _worker_cset_start_region[worker_i]; 2861 assert(result == NULL || result->in_collection_set(), "sanity"); 2862 return result; 2863 } 2864 2865 // The cached entry was not valid so let's calculate 2866 // a suitable starting heap region for this worker. 2867 2868 // We want the parallel threads to start their collection 2869 // set iteration at different collection set regions to 2870 // avoid contention. 2871 // If we have: 2872 // n collection set regions 2873 // p threads 2874 // Then thread t will start at region floor ((t * n) / p) 2875 2876 result = g1_policy()->collection_set(); 2877 if (G1CollectedHeap::use_parallel_gc_threads()) { 2878 uint cs_size = g1_policy()->cset_region_length(); 2879 uint active_workers = workers()->active_workers(); 2880 assert(UseDynamicNumberOfGCThreads || 2881 active_workers == workers()->total_workers(), 2882 "Unless dynamic should use total workers"); 2883 2884 uint end_ind = (cs_size * worker_i) / active_workers; 2885 uint start_ind = 0; 2886 2887 if (worker_i > 0 && 2888 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) { 2889 // Previous workers starting region is valid 2890 // so let's iterate from there 2891 start_ind = (cs_size * (worker_i - 1)) / active_workers; 2892 result = _worker_cset_start_region[worker_i - 1]; 2893 } 2894 2895 for (uint i = start_ind; i < end_ind; i++) { 2896 result = result->next_in_collection_set(); 2897 } 2898 } 2899 2900 // Note: the calculated starting heap region may be NULL 2901 // (when the collection set is empty). 2902 assert(result == NULL || result->in_collection_set(), "sanity"); 2903 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp, 2904 "should be updated only once per pause"); 2905 _worker_cset_start_region[worker_i] = result; 2906 OrderAccess::storestore(); 2907 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp; 2908 return result; 2909 } 2910 2911 HeapRegion* G1CollectedHeap::start_region_for_worker(uint worker_i, 2912 uint no_of_par_workers) { 2913 uint worker_num = 2914 G1CollectedHeap::use_parallel_gc_threads() ? no_of_par_workers : 1U; 2915 assert(UseDynamicNumberOfGCThreads || 2916 no_of_par_workers == workers()->total_workers(), 2917 "Non dynamic should use fixed number of workers"); 2918 const uint start_index = n_regions() * worker_i / worker_num; 2919 return region_at(start_index); 2920 } 2921 2922 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) { 2923 HeapRegion* r = g1_policy()->collection_set(); 2924 while (r != NULL) { 2925 HeapRegion* next = r->next_in_collection_set(); 2926 if (cl->doHeapRegion(r)) { 2927 cl->incomplete(); 2928 return; 2929 } 2930 r = next; 2931 } 2932 } 2933 2934 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r, 2935 HeapRegionClosure *cl) { 2936 if (r == NULL) { 2937 // The CSet is empty so there's nothing to do. 2938 return; 2939 } 2940 2941 assert(r->in_collection_set(), 2942 "Start region must be a member of the collection set."); 2943 HeapRegion* cur = r; 2944 while (cur != NULL) { 2945 HeapRegion* next = cur->next_in_collection_set(); 2946 if (cl->doHeapRegion(cur) && false) { 2947 cl->incomplete(); 2948 return; 2949 } 2950 cur = next; 2951 } 2952 cur = g1_policy()->collection_set(); 2953 while (cur != r) { 2954 HeapRegion* next = cur->next_in_collection_set(); 2955 if (cl->doHeapRegion(cur) && false) { 2956 cl->incomplete(); 2957 return; 2958 } 2959 cur = next; 2960 } 2961 } 2962 2963 CompactibleSpace* G1CollectedHeap::first_compactible_space() { 2964 return n_regions() > 0 ? region_at(0) : NULL; 2965 } 2966 2967 2968 Space* G1CollectedHeap::space_containing(const void* addr) const { 2969 Space* res = heap_region_containing(addr); 2970 return res; 2971 } 2972 2973 HeapWord* G1CollectedHeap::block_start(const void* addr) const { 2974 Space* sp = space_containing(addr); 2975 if (sp != NULL) { 2976 return sp->block_start(addr); 2977 } 2978 return NULL; 2979 } 2980 2981 size_t G1CollectedHeap::block_size(const HeapWord* addr) const { 2982 Space* sp = space_containing(addr); 2983 assert(sp != NULL, "block_size of address outside of heap"); 2984 return sp->block_size(addr); 2985 } 2986 2987 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { 2988 Space* sp = space_containing(addr); 2989 return sp->block_is_obj(addr); 2990 } 2991 2992 bool G1CollectedHeap::supports_tlab_allocation() const { 2993 return true; 2994 } 2995 2996 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { 2997 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes; 2998 } 2999 3000 size_t G1CollectedHeap::tlab_used(Thread* ignored) const { 3001 return young_list()->eden_used_bytes(); 3002 } 3003 3004 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size 3005 // must be smaller than the humongous object limit. 3006 size_t G1CollectedHeap::max_tlab_size() const { 3007 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment); 3008 } 3009 3010 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { 3011 // Return the remaining space in the cur alloc region, but not less than 3012 // the min TLAB size. 3013 3014 // Also, this value can be at most the humongous object threshold, 3015 // since we can't allow tlabs to grow big enough to accommodate 3016 // humongous objects. 3017 3018 HeapRegion* hr = _mutator_alloc_region.get(); 3019 size_t max_tlab = max_tlab_size() * wordSize; 3020 if (hr == NULL) { 3021 return max_tlab; 3022 } else { 3023 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab); 3024 } 3025 } 3026 3027 size_t G1CollectedHeap::max_capacity() const { 3028 return _g1_reserved.byte_size(); 3029 } 3030 3031 jlong G1CollectedHeap::millis_since_last_gc() { 3032 // assert(false, "NYI"); 3033 return 0; 3034 } 3035 3036 void G1CollectedHeap::prepare_for_verify() { 3037 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) { 3038 ensure_parsability(false); 3039 } 3040 g1_rem_set()->prepare_for_verify(); 3041 } 3042 3043 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr, 3044 VerifyOption vo) { 3045 switch (vo) { 3046 case VerifyOption_G1UsePrevMarking: 3047 return hr->obj_allocated_since_prev_marking(obj); 3048 case VerifyOption_G1UseNextMarking: 3049 return hr->obj_allocated_since_next_marking(obj); 3050 case VerifyOption_G1UseMarkWord: 3051 return false; 3052 default: 3053 ShouldNotReachHere(); 3054 } 3055 return false; // keep some compilers happy 3056 } 3057 3058 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) { 3059 switch (vo) { 3060 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start(); 3061 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start(); 3062 case VerifyOption_G1UseMarkWord: return NULL; 3063 default: ShouldNotReachHere(); 3064 } 3065 return NULL; // keep some compilers happy 3066 } 3067 3068 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) { 3069 switch (vo) { 3070 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj); 3071 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj); 3072 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked(); 3073 default: ShouldNotReachHere(); 3074 } 3075 return false; // keep some compilers happy 3076 } 3077 3078 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) { 3079 switch (vo) { 3080 case VerifyOption_G1UsePrevMarking: return "PTAMS"; 3081 case VerifyOption_G1UseNextMarking: return "NTAMS"; 3082 case VerifyOption_G1UseMarkWord: return "NONE"; 3083 default: ShouldNotReachHere(); 3084 } 3085 return NULL; // keep some compilers happy 3086 } 3087 3088 class VerifyRootsClosure: public OopClosure { 3089 private: 3090 G1CollectedHeap* _g1h; 3091 VerifyOption _vo; 3092 bool _failures; 3093 public: 3094 // _vo == UsePrevMarking -> use "prev" marking information, 3095 // _vo == UseNextMarking -> use "next" marking information, 3096 // _vo == UseMarkWord -> use mark word from object header. 3097 VerifyRootsClosure(VerifyOption vo) : 3098 _g1h(G1CollectedHeap::heap()), 3099 _vo(vo), 3100 _failures(false) { } 3101 3102 bool failures() { return _failures; } 3103 3104 template <class T> void do_oop_nv(T* p) { 3105 T heap_oop = oopDesc::load_heap_oop(p); 3106 if (!oopDesc::is_null(heap_oop)) { 3107 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 3108 if (_g1h->is_obj_dead_cond(obj, _vo)) { 3109 gclog_or_tty->print_cr("Root location "PTR_FORMAT" " 3110 "points to dead obj "PTR_FORMAT, p, (void*) obj); 3111 if (_vo == VerifyOption_G1UseMarkWord) { 3112 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark())); 3113 } 3114 obj->print_on(gclog_or_tty); 3115 _failures = true; 3116 } 3117 } 3118 } 3119 3120 void do_oop(oop* p) { do_oop_nv(p); } 3121 void do_oop(narrowOop* p) { do_oop_nv(p); } 3122 }; 3123 3124 class G1VerifyCodeRootOopClosure: public OopClosure { 3125 G1CollectedHeap* _g1h; 3126 OopClosure* _root_cl; 3127 nmethod* _nm; 3128 VerifyOption _vo; 3129 bool _failures; 3130 3131 template <class T> void do_oop_work(T* p) { 3132 // First verify that this root is live 3133 _root_cl->do_oop(p); 3134 3135 if (!G1VerifyHeapRegionCodeRoots) { 3136 // We're not verifying the code roots attached to heap region. 3137 return; 3138 } 3139 3140 // Don't check the code roots during marking verification in a full GC 3141 if (_vo == VerifyOption_G1UseMarkWord) { 3142 return; 3143 } 3144 3145 // Now verify that the current nmethod (which contains p) is 3146 // in the code root list of the heap region containing the 3147 // object referenced by p. 3148 3149 T heap_oop = oopDesc::load_heap_oop(p); 3150 if (!oopDesc::is_null(heap_oop)) { 3151 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 3152 3153 // Now fetch the region containing the object 3154 HeapRegion* hr = _g1h->heap_region_containing(obj); 3155 HeapRegionRemSet* hrrs = hr->rem_set(); 3156 // Verify that the strong code root list for this region 3157 // contains the nmethod 3158 if (!hrrs->strong_code_roots_list_contains(_nm)) { 3159 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" " 3160 "from nmethod "PTR_FORMAT" not in strong " 3161 "code roots for region ["PTR_FORMAT","PTR_FORMAT")", 3162 p, _nm, hr->bottom(), hr->end()); 3163 _failures = true; 3164 } 3165 } 3166 } 3167 3168 public: 3169 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo): 3170 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {} 3171 3172 void do_oop(oop* p) { do_oop_work(p); } 3173 void do_oop(narrowOop* p) { do_oop_work(p); } 3174 3175 void set_nmethod(nmethod* nm) { _nm = nm; } 3176 bool failures() { return _failures; } 3177 }; 3178 3179 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure { 3180 G1VerifyCodeRootOopClosure* _oop_cl; 3181 3182 public: 3183 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl): 3184 _oop_cl(oop_cl) {} 3185 3186 void do_code_blob(CodeBlob* cb) { 3187 nmethod* nm = cb->as_nmethod_or_null(); 3188 if (nm != NULL) { 3189 _oop_cl->set_nmethod(nm); 3190 nm->oops_do(_oop_cl); 3191 } 3192 } 3193 }; 3194 3195 class YoungRefCounterClosure : public OopClosure { 3196 G1CollectedHeap* _g1h; 3197 int _count; 3198 public: 3199 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {} 3200 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } } 3201 void do_oop(narrowOop* p) { ShouldNotReachHere(); } 3202 3203 int count() { return _count; } 3204 void reset_count() { _count = 0; }; 3205 }; 3206 3207 class VerifyKlassClosure: public KlassClosure { 3208 YoungRefCounterClosure _young_ref_counter_closure; 3209 OopClosure *_oop_closure; 3210 public: 3211 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {} 3212 void do_klass(Klass* k) { 3213 k->oops_do(_oop_closure); 3214 3215 _young_ref_counter_closure.reset_count(); 3216 k->oops_do(&_young_ref_counter_closure); 3217 if (_young_ref_counter_closure.count() > 0) { 3218 guarantee(k->has_modified_oops(), err_msg("Klass %p, has young refs but is not dirty.", k)); 3219 } 3220 } 3221 }; 3222 3223 class VerifyLivenessOopClosure: public OopClosure { 3224 G1CollectedHeap* _g1h; 3225 VerifyOption _vo; 3226 public: 3227 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo): 3228 _g1h(g1h), _vo(vo) 3229 { } 3230 void do_oop(narrowOop *p) { do_oop_work(p); } 3231 void do_oop( oop *p) { do_oop_work(p); } 3232 3233 template <class T> void do_oop_work(T *p) { 3234 oop obj = oopDesc::load_decode_heap_oop(p); 3235 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo), 3236 "Dead object referenced by a not dead object"); 3237 } 3238 }; 3239 3240 class VerifyObjsInRegionClosure: public ObjectClosure { 3241 private: 3242 G1CollectedHeap* _g1h; 3243 size_t _live_bytes; 3244 HeapRegion *_hr; 3245 VerifyOption _vo; 3246 public: 3247 // _vo == UsePrevMarking -> use "prev" marking information, 3248 // _vo == UseNextMarking -> use "next" marking information, 3249 // _vo == UseMarkWord -> use mark word from object header. 3250 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo) 3251 : _live_bytes(0), _hr(hr), _vo(vo) { 3252 _g1h = G1CollectedHeap::heap(); 3253 } 3254 void do_object(oop o) { 3255 VerifyLivenessOopClosure isLive(_g1h, _vo); 3256 assert(o != NULL, "Huh?"); 3257 if (!_g1h->is_obj_dead_cond(o, _vo)) { 3258 // If the object is alive according to the mark word, 3259 // then verify that the marking information agrees. 3260 // Note we can't verify the contra-positive of the 3261 // above: if the object is dead (according to the mark 3262 // word), it may not be marked, or may have been marked 3263 // but has since became dead, or may have been allocated 3264 // since the last marking. 3265 if (_vo == VerifyOption_G1UseMarkWord) { 3266 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch"); 3267 } 3268 3269 o->oop_iterate_no_header(&isLive); 3270 if (!_hr->obj_allocated_since_prev_marking(o)) { 3271 size_t obj_size = o->size(); // Make sure we don't overflow 3272 _live_bytes += (obj_size * HeapWordSize); 3273 } 3274 } 3275 } 3276 size_t live_bytes() { return _live_bytes; } 3277 }; 3278 3279 class PrintObjsInRegionClosure : public ObjectClosure { 3280 HeapRegion *_hr; 3281 G1CollectedHeap *_g1; 3282 public: 3283 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) { 3284 _g1 = G1CollectedHeap::heap(); 3285 }; 3286 3287 void do_object(oop o) { 3288 if (o != NULL) { 3289 HeapWord *start = (HeapWord *) o; 3290 size_t word_sz = o->size(); 3291 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT 3292 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n", 3293 (void*) o, word_sz, 3294 _g1->isMarkedPrev(o), 3295 _g1->isMarkedNext(o), 3296 _hr->obj_allocated_since_prev_marking(o)); 3297 HeapWord *end = start + word_sz; 3298 HeapWord *cur; 3299 int *val; 3300 for (cur = start; cur < end; cur++) { 3301 val = (int *) cur; 3302 gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val); 3303 } 3304 } 3305 } 3306 }; 3307 3308 class VerifyRegionClosure: public HeapRegionClosure { 3309 private: 3310 bool _par; 3311 VerifyOption _vo; 3312 bool _failures; 3313 public: 3314 // _vo == UsePrevMarking -> use "prev" marking information, 3315 // _vo == UseNextMarking -> use "next" marking information, 3316 // _vo == UseMarkWord -> use mark word from object header. 3317 VerifyRegionClosure(bool par, VerifyOption vo) 3318 : _par(par), 3319 _vo(vo), 3320 _failures(false) {} 3321 3322 bool failures() { 3323 return _failures; 3324 } 3325 3326 bool doHeapRegion(HeapRegion* r) { 3327 if (!r->continuesHumongous()) { 3328 bool failures = false; 3329 r->verify(_vo, &failures); 3330 if (failures) { 3331 _failures = true; 3332 } else { 3333 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo); 3334 r->object_iterate(¬_dead_yet_cl); 3335 if (_vo != VerifyOption_G1UseNextMarking) { 3336 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) { 3337 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] " 3338 "max_live_bytes "SIZE_FORMAT" " 3339 "< calculated "SIZE_FORMAT, 3340 r->bottom(), r->end(), 3341 r->max_live_bytes(), 3342 not_dead_yet_cl.live_bytes()); 3343 _failures = true; 3344 } 3345 } else { 3346 // When vo == UseNextMarking we cannot currently do a sanity 3347 // check on the live bytes as the calculation has not been 3348 // finalized yet. 3349 } 3350 } 3351 } 3352 return false; // stop the region iteration if we hit a failure 3353 } 3354 }; 3355 3356 // This is the task used for parallel verification of the heap regions 3357 3358 class G1ParVerifyTask: public AbstractGangTask { 3359 private: 3360 G1CollectedHeap* _g1h; 3361 VerifyOption _vo; 3362 bool _failures; 3363 3364 public: 3365 // _vo == UsePrevMarking -> use "prev" marking information, 3366 // _vo == UseNextMarking -> use "next" marking information, 3367 // _vo == UseMarkWord -> use mark word from object header. 3368 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) : 3369 AbstractGangTask("Parallel verify task"), 3370 _g1h(g1h), 3371 _vo(vo), 3372 _failures(false) { } 3373 3374 bool failures() { 3375 return _failures; 3376 } 3377 3378 void work(uint worker_id) { 3379 HandleMark hm; 3380 VerifyRegionClosure blk(true, _vo); 3381 _g1h->heap_region_par_iterate_chunked(&blk, worker_id, 3382 _g1h->workers()->active_workers(), 3383 HeapRegion::ParVerifyClaimValue); 3384 if (blk.failures()) { 3385 _failures = true; 3386 } 3387 } 3388 }; 3389 3390 void G1CollectedHeap::verify(bool silent, VerifyOption vo) { 3391 if (SafepointSynchronize::is_at_safepoint()) { 3392 assert(Thread::current()->is_VM_thread(), 3393 "Expected to be executed serially by the VM thread at this point"); 3394 3395 if (!silent) { gclog_or_tty->print("Roots "); } 3396 VerifyRootsClosure rootsCl(vo); 3397 VerifyKlassClosure klassCl(this, &rootsCl); 3398 3399 // We apply the relevant closures to all the oops in the 3400 // system dictionary, class loader data graph and the string table. 3401 // Don't verify the code cache here, since it's verified below. 3402 const int so = SO_AllClasses | SO_Strings; 3403 3404 // Need cleared claim bits for the strong roots processing 3405 ClassLoaderDataGraph::clear_claimed_marks(); 3406 3407 process_strong_roots(true, // activate StrongRootsScope 3408 ScanningOption(so), // roots scanning options 3409 &rootsCl, 3410 &klassCl 3411 ); 3412 3413 // Verify the nmethods in the code cache. 3414 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo); 3415 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl); 3416 CodeCache::blobs_do(&blobsCl); 3417 3418 bool failures = rootsCl.failures() || codeRootsCl.failures(); 3419 3420 if (vo != VerifyOption_G1UseMarkWord) { 3421 // If we're verifying during a full GC then the region sets 3422 // will have been torn down at the start of the GC. Therefore 3423 // verifying the region sets will fail. So we only verify 3424 // the region sets when not in a full GC. 3425 if (!silent) { gclog_or_tty->print("HeapRegionSets "); } 3426 verify_region_sets(); 3427 } 3428 3429 if (!silent) { gclog_or_tty->print("HeapRegions "); } 3430 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) { 3431 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue), 3432 "sanity check"); 3433 3434 G1ParVerifyTask task(this, vo); 3435 assert(UseDynamicNumberOfGCThreads || 3436 workers()->active_workers() == workers()->total_workers(), 3437 "If not dynamic should be using all the workers"); 3438 int n_workers = workers()->active_workers(); 3439 set_par_threads(n_workers); 3440 workers()->run_task(&task); 3441 set_par_threads(0); 3442 if (task.failures()) { 3443 failures = true; 3444 } 3445 3446 // Checks that the expected amount of parallel work was done. 3447 // The implication is that n_workers is > 0. 3448 assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue), 3449 "sanity check"); 3450 3451 reset_heap_region_claim_values(); 3452 3453 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue), 3454 "sanity check"); 3455 } else { 3456 VerifyRegionClosure blk(false, vo); 3457 heap_region_iterate(&blk); 3458 if (blk.failures()) { 3459 failures = true; 3460 } 3461 } 3462 if (!silent) gclog_or_tty->print("RemSet "); 3463 rem_set()->verify(); 3464 3465 if (failures) { 3466 gclog_or_tty->print_cr("Heap:"); 3467 // It helps to have the per-region information in the output to 3468 // help us track down what went wrong. This is why we call 3469 // print_extended_on() instead of print_on(). 3470 print_extended_on(gclog_or_tty); 3471 gclog_or_tty->print_cr(""); 3472 #ifndef PRODUCT 3473 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) { 3474 concurrent_mark()->print_reachable("at-verification-failure", 3475 vo, false /* all */); 3476 } 3477 #endif 3478 gclog_or_tty->flush(); 3479 } 3480 guarantee(!failures, "there should not have been any failures"); 3481 } else { 3482 if (!silent) 3483 gclog_or_tty->print("(SKIPPING roots, heapRegionSets, heapRegions, remset) "); 3484 } 3485 } 3486 3487 void G1CollectedHeap::verify(bool silent) { 3488 verify(silent, VerifyOption_G1UsePrevMarking); 3489 } 3490 3491 double G1CollectedHeap::verify(bool guard, const char* msg) { 3492 double verify_time_ms = 0.0; 3493 3494 if (guard && total_collections() >= VerifyGCStartAt) { 3495 double verify_start = os::elapsedTime(); 3496 HandleMark hm; // Discard invalid handles created during verification 3497 prepare_for_verify(); 3498 Universe::verify(VerifyOption_G1UsePrevMarking, msg); 3499 verify_time_ms = (os::elapsedTime() - verify_start) * 1000; 3500 } 3501 3502 return verify_time_ms; 3503 } 3504 3505 void G1CollectedHeap::verify_before_gc() { 3506 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:"); 3507 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms); 3508 } 3509 3510 void G1CollectedHeap::verify_after_gc() { 3511 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:"); 3512 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms); 3513 } 3514 3515 class PrintRegionClosure: public HeapRegionClosure { 3516 outputStream* _st; 3517 public: 3518 PrintRegionClosure(outputStream* st) : _st(st) {} 3519 bool doHeapRegion(HeapRegion* r) { 3520 r->print_on(_st); 3521 return false; 3522 } 3523 }; 3524 3525 void G1CollectedHeap::print_on(outputStream* st) const { 3526 st->print(" %-20s", "garbage-first heap"); 3527 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 3528 capacity()/K, used_unlocked()/K); 3529 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")", 3530 _g1_storage.low_boundary(), 3531 _g1_storage.high(), 3532 _g1_storage.high_boundary()); 3533 st->cr(); 3534 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); 3535 uint young_regions = _young_list->length(); 3536 st->print("%u young (" SIZE_FORMAT "K), ", young_regions, 3537 (size_t) young_regions * HeapRegion::GrainBytes / K); 3538 uint survivor_regions = g1_policy()->recorded_survivor_regions(); 3539 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, 3540 (size_t) survivor_regions * HeapRegion::GrainBytes / K); 3541 st->cr(); 3542 MetaspaceAux::print_on(st); 3543 } 3544 3545 void G1CollectedHeap::print_extended_on(outputStream* st) const { 3546 print_on(st); 3547 3548 // Print the per-region information. 3549 st->cr(); 3550 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), " 3551 "HS=humongous(starts), HC=humongous(continues), " 3552 "CS=collection set, F=free, TS=gc time stamp, " 3553 "PTAMS=previous top-at-mark-start, " 3554 "NTAMS=next top-at-mark-start)"); 3555 PrintRegionClosure blk(st); 3556 heap_region_iterate(&blk); 3557 } 3558 3559 void G1CollectedHeap::print_on_error(outputStream* st) const { 3560 this->CollectedHeap::print_on_error(st); 3561 3562 if (_cm != NULL) { 3563 st->cr(); 3564 _cm->print_on_error(st); 3565 } 3566 } 3567 3568 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const { 3569 if (G1CollectedHeap::use_parallel_gc_threads()) { 3570 workers()->print_worker_threads_on(st); 3571 } 3572 _cmThread->print_on(st); 3573 st->cr(); 3574 _cm->print_worker_threads_on(st); 3575 _cg1r->print_worker_threads_on(st); 3576 } 3577 3578 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { 3579 if (G1CollectedHeap::use_parallel_gc_threads()) { 3580 workers()->threads_do(tc); 3581 } 3582 tc->do_thread(_cmThread); 3583 _cg1r->threads_do(tc); 3584 } 3585 3586 void G1CollectedHeap::print_tracing_info() const { 3587 // We'll overload this to mean "trace GC pause statistics." 3588 if (TraceGen0Time || TraceGen1Time) { 3589 // The "G1CollectorPolicy" is keeping track of these stats, so delegate 3590 // to that. 3591 g1_policy()->print_tracing_info(); 3592 } 3593 if (G1SummarizeRSetStats) { 3594 g1_rem_set()->print_summary_info(); 3595 } 3596 if (G1SummarizeConcMark) { 3597 concurrent_mark()->print_summary_info(); 3598 } 3599 g1_policy()->print_yg_surv_rate_info(); 3600 SpecializationStats::print(); 3601 } 3602 3603 #ifndef PRODUCT 3604 // Helpful for debugging RSet issues. 3605 3606 class PrintRSetsClosure : public HeapRegionClosure { 3607 private: 3608 const char* _msg; 3609 size_t _occupied_sum; 3610 3611 public: 3612 bool doHeapRegion(HeapRegion* r) { 3613 HeapRegionRemSet* hrrs = r->rem_set(); 3614 size_t occupied = hrrs->occupied(); 3615 _occupied_sum += occupied; 3616 3617 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT, 3618 HR_FORMAT_PARAMS(r)); 3619 if (occupied == 0) { 3620 gclog_or_tty->print_cr(" RSet is empty"); 3621 } else { 3622 hrrs->print(); 3623 } 3624 gclog_or_tty->print_cr("----------"); 3625 return false; 3626 } 3627 3628 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { 3629 gclog_or_tty->cr(); 3630 gclog_or_tty->print_cr("========================================"); 3631 gclog_or_tty->print_cr(msg); 3632 gclog_or_tty->cr(); 3633 } 3634 3635 ~PrintRSetsClosure() { 3636 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum); 3637 gclog_or_tty->print_cr("========================================"); 3638 gclog_or_tty->cr(); 3639 } 3640 }; 3641 3642 void G1CollectedHeap::print_cset_rsets() { 3643 PrintRSetsClosure cl("Printing CSet RSets"); 3644 collection_set_iterate(&cl); 3645 } 3646 3647 void G1CollectedHeap::print_all_rsets() { 3648 PrintRSetsClosure cl("Printing All RSets");; 3649 heap_region_iterate(&cl); 3650 } 3651 #endif // PRODUCT 3652 3653 G1CollectedHeap* G1CollectedHeap::heap() { 3654 assert(_sh->kind() == CollectedHeap::G1CollectedHeap, 3655 "not a garbage-first heap"); 3656 return _g1h; 3657 } 3658 3659 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) { 3660 // always_do_update_barrier = false; 3661 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 3662 // Fill TLAB's and such 3663 accumulate_statistics_all_tlabs(); 3664 ensure_parsability(true); 3665 3666 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) && 3667 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) { 3668 g1_rem_set()->print_periodic_summary_info("Before GC RS summary"); 3669 } 3670 } 3671 3672 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) { 3673 3674 if (G1SummarizeRSetStats && 3675 (G1SummarizeRSetStatsPeriod > 0) && 3676 // we are at the end of the GC. Total collections has already been increased. 3677 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) { 3678 g1_rem_set()->print_periodic_summary_info("After GC RS summary"); 3679 } 3680 3681 // FIXME: what is this about? 3682 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" 3683 // is set. 3684 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(), 3685 "derived pointer present")); 3686 // always_do_update_barrier = true; 3687 3688 resize_all_tlabs(); 3689 3690 // We have just completed a GC. Update the soft reference 3691 // policy with the new heap occupancy 3692 Universe::update_heap_info_at_gc(); 3693 } 3694 3695 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, 3696 unsigned int gc_count_before, 3697 bool* succeeded, 3698 GCCause::Cause gc_cause) { 3699 assert_heap_not_locked_and_not_at_safepoint(); 3700 g1_policy()->record_stop_world_start(); 3701 VM_G1IncCollectionPause op(gc_count_before, 3702 word_size, 3703 false, /* should_initiate_conc_mark */ 3704 g1_policy()->max_pause_time_ms(), 3705 gc_cause); 3706 VMThread::execute(&op); 3707 3708 HeapWord* result = op.result(); 3709 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded(); 3710 assert(result == NULL || ret_succeeded, 3711 "the result should be NULL if the VM did not succeed"); 3712 *succeeded = ret_succeeded; 3713 3714 assert_heap_not_locked(); 3715 return result; 3716 } 3717 3718 void 3719 G1CollectedHeap::doConcurrentMark() { 3720 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); 3721 if (!_cmThread->in_progress()) { 3722 _cmThread->set_started(); 3723 CGC_lock->notify(); 3724 } 3725 } 3726 3727 size_t G1CollectedHeap::pending_card_num() { 3728 size_t extra_cards = 0; 3729 JavaThread *curr = Threads::first(); 3730 while (curr != NULL) { 3731 DirtyCardQueue& dcq = curr->dirty_card_queue(); 3732 extra_cards += dcq.size(); 3733 curr = curr->next(); 3734 } 3735 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 3736 size_t buffer_size = dcqs.buffer_size(); 3737 size_t buffer_num = dcqs.completed_buffers_num(); 3738 3739 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes 3740 // in bytes - not the number of 'entries'. We need to convert 3741 // into a number of cards. 3742 return (buffer_size * buffer_num + extra_cards) / oopSize; 3743 } 3744 3745 size_t G1CollectedHeap::cards_scanned() { 3746 return g1_rem_set()->cardsScanned(); 3747 } 3748 3749 void 3750 G1CollectedHeap::setup_surviving_young_words() { 3751 assert(_surviving_young_words == NULL, "pre-condition"); 3752 uint array_length = g1_policy()->young_cset_region_length(); 3753 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC); 3754 if (_surviving_young_words == NULL) { 3755 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR, 3756 "Not enough space for young surv words summary."); 3757 } 3758 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t)); 3759 #ifdef ASSERT 3760 for (uint i = 0; i < array_length; ++i) { 3761 assert( _surviving_young_words[i] == 0, "memset above" ); 3762 } 3763 #endif // !ASSERT 3764 } 3765 3766 void 3767 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) { 3768 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); 3769 uint array_length = g1_policy()->young_cset_region_length(); 3770 for (uint i = 0; i < array_length; ++i) { 3771 _surviving_young_words[i] += surv_young_words[i]; 3772 } 3773 } 3774 3775 void 3776 G1CollectedHeap::cleanup_surviving_young_words() { 3777 guarantee( _surviving_young_words != NULL, "pre-condition" ); 3778 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words, mtGC); 3779 _surviving_young_words = NULL; 3780 } 3781 3782 #ifdef ASSERT 3783 class VerifyCSetClosure: public HeapRegionClosure { 3784 public: 3785 bool doHeapRegion(HeapRegion* hr) { 3786 // Here we check that the CSet region's RSet is ready for parallel 3787 // iteration. The fields that we'll verify are only manipulated 3788 // when the region is part of a CSet and is collected. Afterwards, 3789 // we reset these fields when we clear the region's RSet (when the 3790 // region is freed) so they are ready when the region is 3791 // re-allocated. The only exception to this is if there's an 3792 // evacuation failure and instead of freeing the region we leave 3793 // it in the heap. In that case, we reset these fields during 3794 // evacuation failure handling. 3795 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification"); 3796 3797 // Here's a good place to add any other checks we'd like to 3798 // perform on CSet regions. 3799 return false; 3800 } 3801 }; 3802 #endif // ASSERT 3803 3804 #if TASKQUEUE_STATS 3805 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) { 3806 st->print_raw_cr("GC Task Stats"); 3807 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); 3808 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); 3809 } 3810 3811 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const { 3812 print_taskqueue_stats_hdr(st); 3813 3814 TaskQueueStats totals; 3815 const int n = workers() != NULL ? workers()->total_workers() : 1; 3816 for (int i = 0; i < n; ++i) { 3817 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr(); 3818 totals += task_queue(i)->stats; 3819 } 3820 st->print_raw("tot "); totals.print(st); st->cr(); 3821 3822 DEBUG_ONLY(totals.verify()); 3823 } 3824 3825 void G1CollectedHeap::reset_taskqueue_stats() { 3826 const int n = workers() != NULL ? workers()->total_workers() : 1; 3827 for (int i = 0; i < n; ++i) { 3828 task_queue(i)->stats.reset(); 3829 } 3830 } 3831 #endif // TASKQUEUE_STATS 3832 3833 void G1CollectedHeap::log_gc_header() { 3834 if (!G1Log::fine()) { 3835 return; 3836 } 3837 3838 gclog_or_tty->date_stamp(PrintGCDateStamps); 3839 gclog_or_tty->stamp(PrintGCTimeStamps); 3840 3841 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause()) 3842 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)") 3843 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : ""); 3844 3845 gclog_or_tty->print("[%s", (const char*)gc_cause_str); 3846 } 3847 3848 void G1CollectedHeap::log_gc_footer(double pause_time_sec) { 3849 if (!G1Log::fine()) { 3850 return; 3851 } 3852 3853 if (G1Log::finer()) { 3854 if (evacuation_failed()) { 3855 gclog_or_tty->print(" (to-space exhausted)"); 3856 } 3857 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec); 3858 g1_policy()->phase_times()->note_gc_end(); 3859 g1_policy()->phase_times()->print(pause_time_sec); 3860 g1_policy()->print_detailed_heap_transition(); 3861 } else { 3862 if (evacuation_failed()) { 3863 gclog_or_tty->print("--"); 3864 } 3865 g1_policy()->print_heap_transition(); 3866 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec); 3867 } 3868 gclog_or_tty->flush(); 3869 } 3870 3871 bool 3872 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { 3873 assert_at_safepoint(true /* should_be_vm_thread */); 3874 guarantee(!is_gc_active(), "collection is not reentrant"); 3875 3876 if (GC_locker::check_active_before_gc()) { 3877 return false; 3878 } 3879 3880 _gc_timer_stw->register_gc_start(); 3881 3882 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start()); 3883 3884 SvcGCMarker sgcm(SvcGCMarker::MINOR); 3885 ResourceMark rm; 3886 3887 print_heap_before_gc(); 3888 trace_heap_before_gc(_gc_tracer_stw); 3889 3890 HRSPhaseSetter x(HRSPhaseEvacuation); 3891 verify_region_sets_optional(); 3892 verify_dirty_young_regions(); 3893 3894 // This call will decide whether this pause is an initial-mark 3895 // pause. If it is, during_initial_mark_pause() will return true 3896 // for the duration of this pause. 3897 g1_policy()->decide_on_conc_mark_initiation(); 3898 3899 // We do not allow initial-mark to be piggy-backed on a mixed GC. 3900 assert(!g1_policy()->during_initial_mark_pause() || 3901 g1_policy()->gcs_are_young(), "sanity"); 3902 3903 // We also do not allow mixed GCs during marking. 3904 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity"); 3905 3906 // Record whether this pause is an initial mark. When the current 3907 // thread has completed its logging output and it's safe to signal 3908 // the CM thread, the flag's value in the policy has been reset. 3909 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause(); 3910 3911 // Inner scope for scope based logging, timers, and stats collection 3912 { 3913 EvacuationInfo evacuation_info; 3914 3915 if (g1_policy()->during_initial_mark_pause()) { 3916 // We are about to start a marking cycle, so we increment the 3917 // full collection counter. 3918 increment_old_marking_cycles_started(); 3919 register_concurrent_cycle_start(_gc_timer_stw->gc_start()); 3920 } 3921 3922 _gc_tracer_stw->report_yc_type(yc_type()); 3923 3924 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty); 3925 3926 int active_workers = (G1CollectedHeap::use_parallel_gc_threads() ? 3927 workers()->active_workers() : 1); 3928 double pause_start_sec = os::elapsedTime(); 3929 g1_policy()->phase_times()->note_gc_start(active_workers); 3930 log_gc_header(); 3931 3932 TraceCollectorStats tcs(g1mm()->incremental_collection_counters()); 3933 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause()); 3934 3935 // If the secondary_free_list is not empty, append it to the 3936 // free_list. No need to wait for the cleanup operation to finish; 3937 // the region allocation code will check the secondary_free_list 3938 // and wait if necessary. If the G1StressConcRegionFreeing flag is 3939 // set, skip this step so that the region allocation code has to 3940 // get entries from the secondary_free_list. 3941 if (!G1StressConcRegionFreeing) { 3942 append_secondary_free_list_if_not_empty_with_lock(); 3943 } 3944 3945 assert(check_young_list_well_formed(), "young list should be well formed"); 3946 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue), 3947 "sanity check"); 3948 3949 // Don't dynamically change the number of GC threads this early. A value of 3950 // 0 is used to indicate serial work. When parallel work is done, 3951 // it will be set. 3952 3953 { // Call to jvmpi::post_class_unload_events must occur outside of active GC 3954 IsGCActiveMark x; 3955 3956 gc_prologue(false); 3957 increment_total_collections(false /* full gc */); 3958 increment_gc_time_stamp(); 3959 3960 verify_before_gc(); 3961 3962 COMPILER2_PRESENT(DerivedPointerTable::clear()); 3963 3964 // Please see comment in g1CollectedHeap.hpp and 3965 // G1CollectedHeap::ref_processing_init() to see how 3966 // reference processing currently works in G1. 3967 3968 // Enable discovery in the STW reference processor 3969 ref_processor_stw()->enable_discovery(true /*verify_disabled*/, 3970 true /*verify_no_refs*/); 3971 3972 { 3973 // We want to temporarily turn off discovery by the 3974 // CM ref processor, if necessary, and turn it back on 3975 // on again later if we do. Using a scoped 3976 // NoRefDiscovery object will do this. 3977 NoRefDiscovery no_cm_discovery(ref_processor_cm()); 3978 3979 // Forget the current alloc region (we might even choose it to be part 3980 // of the collection set!). 3981 release_mutator_alloc_region(); 3982 3983 // We should call this after we retire the mutator alloc 3984 // region(s) so that all the ALLOC / RETIRE events are generated 3985 // before the start GC event. 3986 _hr_printer.start_gc(false /* full */, (size_t) total_collections()); 3987 3988 // This timing is only used by the ergonomics to handle our pause target. 3989 // It is unclear why this should not include the full pause. We will 3990 // investigate this in CR 7178365. 3991 // 3992 // Preserving the old comment here if that helps the investigation: 3993 // 3994 // The elapsed time induced by the start time below deliberately elides 3995 // the possible verification above. 3996 double sample_start_time_sec = os::elapsedTime(); 3997 3998 #if YOUNG_LIST_VERBOSE 3999 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:"); 4000 _young_list->print(); 4001 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 4002 #endif // YOUNG_LIST_VERBOSE 4003 4004 g1_policy()->record_collection_pause_start(sample_start_time_sec); 4005 4006 double scan_wait_start = os::elapsedTime(); 4007 // We have to wait until the CM threads finish scanning the 4008 // root regions as it's the only way to ensure that all the 4009 // objects on them have been correctly scanned before we start 4010 // moving them during the GC. 4011 bool waited = _cm->root_regions()->wait_until_scan_finished(); 4012 double wait_time_ms = 0.0; 4013 if (waited) { 4014 double scan_wait_end = os::elapsedTime(); 4015 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0; 4016 } 4017 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms); 4018 4019 #if YOUNG_LIST_VERBOSE 4020 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:"); 4021 _young_list->print(); 4022 #endif // YOUNG_LIST_VERBOSE 4023 4024 if (g1_policy()->during_initial_mark_pause()) { 4025 concurrent_mark()->checkpointRootsInitialPre(); 4026 } 4027 4028 #if YOUNG_LIST_VERBOSE 4029 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:"); 4030 _young_list->print(); 4031 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 4032 #endif // YOUNG_LIST_VERBOSE 4033 4034 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info); 4035 4036 _cm->note_start_of_gc(); 4037 // We should not verify the per-thread SATB buffers given that 4038 // we have not filtered them yet (we'll do so during the 4039 // GC). We also call this after finalize_cset() to 4040 // ensure that the CSet has been finalized. 4041 _cm->verify_no_cset_oops(true /* verify_stacks */, 4042 true /* verify_enqueued_buffers */, 4043 false /* verify_thread_buffers */, 4044 true /* verify_fingers */); 4045 4046 if (_hr_printer.is_active()) { 4047 HeapRegion* hr = g1_policy()->collection_set(); 4048 while (hr != NULL) { 4049 G1HRPrinter::RegionType type; 4050 if (!hr->is_young()) { 4051 type = G1HRPrinter::Old; 4052 } else if (hr->is_survivor()) { 4053 type = G1HRPrinter::Survivor; 4054 } else { 4055 type = G1HRPrinter::Eden; 4056 } 4057 _hr_printer.cset(hr); 4058 hr = hr->next_in_collection_set(); 4059 } 4060 } 4061 4062 #ifdef ASSERT 4063 VerifyCSetClosure cl; 4064 collection_set_iterate(&cl); 4065 #endif // ASSERT 4066 4067 setup_surviving_young_words(); 4068 4069 // Initialize the GC alloc regions. 4070 init_gc_alloc_regions(evacuation_info); 4071 4072 // Actually do the work... 4073 evacuate_collection_set(evacuation_info); 4074 4075 // We do this to mainly verify the per-thread SATB buffers 4076 // (which have been filtered by now) since we didn't verify 4077 // them earlier. No point in re-checking the stacks / enqueued 4078 // buffers given that the CSet has not changed since last time 4079 // we checked. 4080 _cm->verify_no_cset_oops(false /* verify_stacks */, 4081 false /* verify_enqueued_buffers */, 4082 true /* verify_thread_buffers */, 4083 true /* verify_fingers */); 4084 4085 free_collection_set(g1_policy()->collection_set(), evacuation_info); 4086 g1_policy()->clear_collection_set(); 4087 4088 cleanup_surviving_young_words(); 4089 4090 // Start a new incremental collection set for the next pause. 4091 g1_policy()->start_incremental_cset_building(); 4092 4093 // Clear the _cset_fast_test bitmap in anticipation of adding 4094 // regions to the incremental collection set for the next 4095 // evacuation pause. 4096 clear_cset_fast_test(); 4097 4098 _young_list->reset_sampled_info(); 4099 4100 // Don't check the whole heap at this point as the 4101 // GC alloc regions from this pause have been tagged 4102 // as survivors and moved on to the survivor list. 4103 // Survivor regions will fail the !is_young() check. 4104 assert(check_young_list_empty(false /* check_heap */), 4105 "young list should be empty"); 4106 4107 #if YOUNG_LIST_VERBOSE 4108 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:"); 4109 _young_list->print(); 4110 #endif // YOUNG_LIST_VERBOSE 4111 4112 g1_policy()->record_survivor_regions(_young_list->survivor_length(), 4113 _young_list->first_survivor_region(), 4114 _young_list->last_survivor_region()); 4115 4116 _young_list->reset_auxilary_lists(); 4117 4118 if (evacuation_failed()) { 4119 _summary_bytes_used = recalculate_used(); 4120 uint n_queues = MAX2((int)ParallelGCThreads, 1); 4121 for (uint i = 0; i < n_queues; i++) { 4122 if (_evacuation_failed_info_array[i].has_failed()) { 4123 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]); 4124 } 4125 } 4126 } else { 4127 // The "used" of the the collection set have already been subtracted 4128 // when they were freed. Add in the bytes evacuated. 4129 _summary_bytes_used += g1_policy()->bytes_copied_during_gc(); 4130 } 4131 4132 if (g1_policy()->during_initial_mark_pause()) { 4133 // We have to do this before we notify the CM threads that 4134 // they can start working to make sure that all the 4135 // appropriate initialization is done on the CM object. 4136 concurrent_mark()->checkpointRootsInitialPost(); 4137 set_marking_started(); 4138 // Note that we don't actually trigger the CM thread at 4139 // this point. We do that later when we're sure that 4140 // the current thread has completed its logging output. 4141 } 4142 4143 allocate_dummy_regions(); 4144 4145 #if YOUNG_LIST_VERBOSE 4146 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:"); 4147 _young_list->print(); 4148 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 4149 #endif // YOUNG_LIST_VERBOSE 4150 4151 init_mutator_alloc_region(); 4152 4153 { 4154 size_t expand_bytes = g1_policy()->expansion_amount(); 4155 if (expand_bytes > 0) { 4156 size_t bytes_before = capacity(); 4157 // No need for an ergo verbose message here, 4158 // expansion_amount() does this when it returns a value > 0. 4159 if (!expand(expand_bytes)) { 4160 // We failed to expand the heap so let's verify that 4161 // committed/uncommitted amount match the backing store 4162 assert(capacity() == _g1_storage.committed_size(), "committed size mismatch"); 4163 assert(max_capacity() == _g1_storage.reserved_size(), "reserved size mismatch"); 4164 } 4165 } 4166 } 4167 4168 // We redo the verification but now wrt to the new CSet which 4169 // has just got initialized after the previous CSet was freed. 4170 _cm->verify_no_cset_oops(true /* verify_stacks */, 4171 true /* verify_enqueued_buffers */, 4172 true /* verify_thread_buffers */, 4173 true /* verify_fingers */); 4174 _cm->note_end_of_gc(); 4175 4176 // This timing is only used by the ergonomics to handle our pause target. 4177 // It is unclear why this should not include the full pause. We will 4178 // investigate this in CR 7178365. 4179 double sample_end_time_sec = os::elapsedTime(); 4180 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; 4181 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info); 4182 4183 MemoryService::track_memory_usage(); 4184 4185 // In prepare_for_verify() below we'll need to scan the deferred 4186 // update buffers to bring the RSets up-to-date if 4187 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning 4188 // the update buffers we'll probably need to scan cards on the 4189 // regions we just allocated to (i.e., the GC alloc 4190 // regions). However, during the last GC we called 4191 // set_saved_mark() on all the GC alloc regions, so card 4192 // scanning might skip the [saved_mark_word()...top()] area of 4193 // those regions (i.e., the area we allocated objects into 4194 // during the last GC). But it shouldn't. Given that 4195 // saved_mark_word() is conditional on whether the GC time stamp 4196 // on the region is current or not, by incrementing the GC time 4197 // stamp here we invalidate all the GC time stamps on all the 4198 // regions and saved_mark_word() will simply return top() for 4199 // all the regions. This is a nicer way of ensuring this rather 4200 // than iterating over the regions and fixing them. In fact, the 4201 // GC time stamp increment here also ensures that 4202 // saved_mark_word() will return top() between pauses, i.e., 4203 // during concurrent refinement. So we don't need the 4204 // is_gc_active() check to decided which top to use when 4205 // scanning cards (see CR 7039627). 4206 increment_gc_time_stamp(); 4207 4208 verify_after_gc(); 4209 4210 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 4211 ref_processor_stw()->verify_no_references_recorded(); 4212 4213 // CM reference discovery will be re-enabled if necessary. 4214 } 4215 4216 // We should do this after we potentially expand the heap so 4217 // that all the COMMIT events are generated before the end GC 4218 // event, and after we retire the GC alloc regions so that all 4219 // RETIRE events are generated before the end GC event. 4220 _hr_printer.end_gc(false /* full */, (size_t) total_collections()); 4221 4222 if (mark_in_progress()) { 4223 concurrent_mark()->update_g1_committed(); 4224 } 4225 4226 #ifdef TRACESPINNING 4227 ParallelTaskTerminator::print_termination_counts(); 4228 #endif 4229 4230 gc_epilogue(false); 4231 } 4232 4233 // Print the remainder of the GC log output. 4234 log_gc_footer(os::elapsedTime() - pause_start_sec); 4235 4236 // It is not yet to safe to tell the concurrent mark to 4237 // start as we have some optional output below. We don't want the 4238 // output from the concurrent mark thread interfering with this 4239 // logging output either. 4240 4241 _hrs.verify_optional(); 4242 verify_region_sets_optional(); 4243 4244 TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats()); 4245 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); 4246 4247 print_heap_after_gc(); 4248 trace_heap_after_gc(_gc_tracer_stw); 4249 4250 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 4251 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 4252 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 4253 // before any GC notifications are raised. 4254 g1mm()->update_sizes(); 4255 4256 _gc_tracer_stw->report_evacuation_info(&evacuation_info); 4257 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold()); 4258 _gc_timer_stw->register_gc_end(); 4259 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions()); 4260 } 4261 // It should now be safe to tell the concurrent mark thread to start 4262 // without its logging output interfering with the logging output 4263 // that came from the pause. 4264 4265 if (should_start_conc_mark) { 4266 // CAUTION: after the doConcurrentMark() call below, 4267 // the concurrent marking thread(s) could be running 4268 // concurrently with us. Make sure that anything after 4269 // this point does not assume that we are the only GC thread 4270 // running. Note: of course, the actual marking work will 4271 // not start until the safepoint itself is released in 4272 // ConcurrentGCThread::safepoint_desynchronize(). 4273 doConcurrentMark(); 4274 } 4275 4276 return true; 4277 } 4278 4279 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose) 4280 { 4281 size_t gclab_word_size; 4282 switch (purpose) { 4283 case GCAllocForSurvived: 4284 gclab_word_size = _survivor_plab_stats.desired_plab_sz(); 4285 break; 4286 case GCAllocForTenured: 4287 gclab_word_size = _old_plab_stats.desired_plab_sz(); 4288 break; 4289 default: 4290 assert(false, "unknown GCAllocPurpose"); 4291 gclab_word_size = _old_plab_stats.desired_plab_sz(); 4292 break; 4293 } 4294 4295 // Prevent humongous PLAB sizes for two reasons: 4296 // * PLABs are allocated using a similar paths as oops, but should 4297 // never be in a humongous region 4298 // * Allowing humongous PLABs needlessly churns the region free lists 4299 return MIN2(_humongous_object_threshold_in_words, gclab_word_size); 4300 } 4301 4302 void G1CollectedHeap::init_mutator_alloc_region() { 4303 assert(_mutator_alloc_region.get() == NULL, "pre-condition"); 4304 _mutator_alloc_region.init(); 4305 } 4306 4307 void G1CollectedHeap::release_mutator_alloc_region() { 4308 _mutator_alloc_region.release(); 4309 assert(_mutator_alloc_region.get() == NULL, "post-condition"); 4310 } 4311 4312 void G1CollectedHeap::init_gc_alloc_regions(EvacuationInfo& evacuation_info) { 4313 assert_at_safepoint(true /* should_be_vm_thread */); 4314 4315 _survivor_gc_alloc_region.init(); 4316 _old_gc_alloc_region.init(); 4317 HeapRegion* retained_region = _retained_old_gc_alloc_region; 4318 _retained_old_gc_alloc_region = NULL; 4319 4320 // We will discard the current GC alloc region if: 4321 // a) it's in the collection set (it can happen!), 4322 // b) it's already full (no point in using it), 4323 // c) it's empty (this means that it was emptied during 4324 // a cleanup and it should be on the free list now), or 4325 // d) it's humongous (this means that it was emptied 4326 // during a cleanup and was added to the free list, but 4327 // has been subsequently used to allocate a humongous 4328 // object that may be less than the region size). 4329 if (retained_region != NULL && 4330 !retained_region->in_collection_set() && 4331 !(retained_region->top() == retained_region->end()) && 4332 !retained_region->is_empty() && 4333 !retained_region->isHumongous()) { 4334 retained_region->set_saved_mark(); 4335 // The retained region was added to the old region set when it was 4336 // retired. We have to remove it now, since we don't allow regions 4337 // we allocate to in the region sets. We'll re-add it later, when 4338 // it's retired again. 4339 _old_set.remove(retained_region); 4340 bool during_im = g1_policy()->during_initial_mark_pause(); 4341 retained_region->note_start_of_copying(during_im); 4342 _old_gc_alloc_region.set(retained_region); 4343 _hr_printer.reuse(retained_region); 4344 evacuation_info.set_alloc_regions_used_before(retained_region->used()); 4345 } 4346 } 4347 4348 void G1CollectedHeap::release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info) { 4349 evacuation_info.set_allocation_regions(_survivor_gc_alloc_region.count() + 4350 _old_gc_alloc_region.count()); 4351 _survivor_gc_alloc_region.release(); 4352 // If we have an old GC alloc region to release, we'll save it in 4353 // _retained_old_gc_alloc_region. If we don't 4354 // _retained_old_gc_alloc_region will become NULL. This is what we 4355 // want either way so no reason to check explicitly for either 4356 // condition. 4357 _retained_old_gc_alloc_region = _old_gc_alloc_region.release(); 4358 4359 if (ResizePLAB) { 4360 _survivor_plab_stats.adjust_desired_plab_sz(no_of_gc_workers); 4361 _old_plab_stats.adjust_desired_plab_sz(no_of_gc_workers); 4362 } 4363 } 4364 4365 void G1CollectedHeap::abandon_gc_alloc_regions() { 4366 assert(_survivor_gc_alloc_region.get() == NULL, "pre-condition"); 4367 assert(_old_gc_alloc_region.get() == NULL, "pre-condition"); 4368 _retained_old_gc_alloc_region = NULL; 4369 } 4370 4371 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) { 4372 _drain_in_progress = false; 4373 set_evac_failure_closure(cl); 4374 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true); 4375 } 4376 4377 void G1CollectedHeap::finalize_for_evac_failure() { 4378 assert(_evac_failure_scan_stack != NULL && 4379 _evac_failure_scan_stack->length() == 0, 4380 "Postcondition"); 4381 assert(!_drain_in_progress, "Postcondition"); 4382 delete _evac_failure_scan_stack; 4383 _evac_failure_scan_stack = NULL; 4384 } 4385 4386 void G1CollectedHeap::remove_self_forwarding_pointers() { 4387 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity"); 4388 4389 G1ParRemoveSelfForwardPtrsTask rsfp_task(this); 4390 4391 if (G1CollectedHeap::use_parallel_gc_threads()) { 4392 set_par_threads(); 4393 workers()->run_task(&rsfp_task); 4394 set_par_threads(0); 4395 } else { 4396 rsfp_task.work(0); 4397 } 4398 4399 assert(check_cset_heap_region_claim_values(HeapRegion::ParEvacFailureClaimValue), "sanity"); 4400 4401 // Reset the claim values in the regions in the collection set. 4402 reset_cset_heap_region_claim_values(); 4403 4404 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity"); 4405 4406 // Now restore saved marks, if any. 4407 assert(_objs_with_preserved_marks.size() == 4408 _preserved_marks_of_objs.size(), "Both or none."); 4409 while (!_objs_with_preserved_marks.is_empty()) { 4410 oop obj = _objs_with_preserved_marks.pop(); 4411 markOop m = _preserved_marks_of_objs.pop(); 4412 obj->set_mark(m); 4413 } 4414 _objs_with_preserved_marks.clear(true); 4415 _preserved_marks_of_objs.clear(true); 4416 } 4417 4418 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) { 4419 _evac_failure_scan_stack->push(obj); 4420 } 4421 4422 void G1CollectedHeap::drain_evac_failure_scan_stack() { 4423 assert(_evac_failure_scan_stack != NULL, "precondition"); 4424 4425 while (_evac_failure_scan_stack->length() > 0) { 4426 oop obj = _evac_failure_scan_stack->pop(); 4427 _evac_failure_closure->set_region(heap_region_containing(obj)); 4428 obj->oop_iterate_backwards(_evac_failure_closure); 4429 } 4430 } 4431 4432 oop 4433 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state, 4434 oop old) { 4435 assert(obj_in_cs(old), 4436 err_msg("obj: "PTR_FORMAT" should still be in the CSet", 4437 (HeapWord*) old)); 4438 markOop m = old->mark(); 4439 oop forward_ptr = old->forward_to_atomic(old); 4440 if (forward_ptr == NULL) { 4441 // Forward-to-self succeeded. 4442 assert(_par_scan_state != NULL, "par scan state"); 4443 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure(); 4444 uint queue_num = _par_scan_state->queue_num(); 4445 4446 _evacuation_failed = true; 4447 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size()); 4448 if (_evac_failure_closure != cl) { 4449 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag); 4450 assert(!_drain_in_progress, 4451 "Should only be true while someone holds the lock."); 4452 // Set the global evac-failure closure to the current thread's. 4453 assert(_evac_failure_closure == NULL, "Or locking has failed."); 4454 set_evac_failure_closure(cl); 4455 // Now do the common part. 4456 handle_evacuation_failure_common(old, m); 4457 // Reset to NULL. 4458 set_evac_failure_closure(NULL); 4459 } else { 4460 // The lock is already held, and this is recursive. 4461 assert(_drain_in_progress, "This should only be the recursive case."); 4462 handle_evacuation_failure_common(old, m); 4463 } 4464 return old; 4465 } else { 4466 // Forward-to-self failed. Either someone else managed to allocate 4467 // space for this object (old != forward_ptr) or they beat us in 4468 // self-forwarding it (old == forward_ptr). 4469 assert(old == forward_ptr || !obj_in_cs(forward_ptr), 4470 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" " 4471 "should not be in the CSet", 4472 (HeapWord*) old, (HeapWord*) forward_ptr)); 4473 return forward_ptr; 4474 } 4475 } 4476 4477 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) { 4478 preserve_mark_if_necessary(old, m); 4479 4480 HeapRegion* r = heap_region_containing(old); 4481 if (!r->evacuation_failed()) { 4482 r->set_evacuation_failed(true); 4483 _hr_printer.evac_failure(r); 4484 } 4485 4486 push_on_evac_failure_scan_stack(old); 4487 4488 if (!_drain_in_progress) { 4489 // prevent recursion in copy_to_survivor_space() 4490 _drain_in_progress = true; 4491 drain_evac_failure_scan_stack(); 4492 _drain_in_progress = false; 4493 } 4494 } 4495 4496 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) { 4497 assert(evacuation_failed(), "Oversaving!"); 4498 // We want to call the "for_promotion_failure" version only in the 4499 // case of a promotion failure. 4500 if (m->must_be_preserved_for_promotion_failure(obj)) { 4501 _objs_with_preserved_marks.push(obj); 4502 _preserved_marks_of_objs.push(m); 4503 } 4504 } 4505 4506 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose, 4507 size_t word_size) { 4508 if (purpose == GCAllocForSurvived) { 4509 HeapWord* result = survivor_attempt_allocation(word_size); 4510 if (result != NULL) { 4511 return result; 4512 } else { 4513 // Let's try to allocate in the old gen in case we can fit the 4514 // object there. 4515 return old_attempt_allocation(word_size); 4516 } 4517 } else { 4518 assert(purpose == GCAllocForTenured, "sanity"); 4519 HeapWord* result = old_attempt_allocation(word_size); 4520 if (result != NULL) { 4521 return result; 4522 } else { 4523 // Let's try to allocate in the survivors in case we can fit the 4524 // object there. 4525 return survivor_attempt_allocation(word_size); 4526 } 4527 } 4528 4529 ShouldNotReachHere(); 4530 // Trying to keep some compilers happy. 4531 return NULL; 4532 } 4533 4534 G1ParGCAllocBuffer::G1ParGCAllocBuffer(size_t gclab_word_size) : 4535 ParGCAllocBuffer(gclab_word_size), _retired(false) { } 4536 4537 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num) 4538 : _g1h(g1h), 4539 _refs(g1h->task_queue(queue_num)), 4540 _dcq(&g1h->dirty_card_queue_set()), 4541 _ct_bs(g1h->g1_barrier_set()), 4542 _g1_rem(g1h->g1_rem_set()), 4543 _hash_seed(17), _queue_num(queue_num), 4544 _term_attempts(0), 4545 _surviving_alloc_buffer(g1h->desired_plab_sz(GCAllocForSurvived)), 4546 _tenured_alloc_buffer(g1h->desired_plab_sz(GCAllocForTenured)), 4547 _age_table(false), 4548 _strong_roots_time(0), _term_time(0), 4549 _alloc_buffer_waste(0), _undo_waste(0) { 4550 // we allocate G1YoungSurvRateNumRegions plus one entries, since 4551 // we "sacrifice" entry 0 to keep track of surviving bytes for 4552 // non-young regions (where the age is -1) 4553 // We also add a few elements at the beginning and at the end in 4554 // an attempt to eliminate cache contention 4555 uint real_length = 1 + _g1h->g1_policy()->young_cset_region_length(); 4556 uint array_length = PADDING_ELEM_NUM + 4557 real_length + 4558 PADDING_ELEM_NUM; 4559 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length, mtGC); 4560 if (_surviving_young_words_base == NULL) 4561 vm_exit_out_of_memory(array_length * sizeof(size_t), OOM_MALLOC_ERROR, 4562 "Not enough space for young surv histo."); 4563 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM; 4564 memset(_surviving_young_words, 0, (size_t) real_length * sizeof(size_t)); 4565 4566 _alloc_buffers[GCAllocForSurvived] = &_surviving_alloc_buffer; 4567 _alloc_buffers[GCAllocForTenured] = &_tenured_alloc_buffer; 4568 4569 _start = os::elapsedTime(); 4570 } 4571 4572 void 4573 G1ParScanThreadState::print_termination_stats_hdr(outputStream* const st) 4574 { 4575 st->print_raw_cr("GC Termination Stats"); 4576 st->print_raw_cr(" elapsed --strong roots-- -------termination-------" 4577 " ------waste (KiB)------"); 4578 st->print_raw_cr("thr ms ms % ms % attempts" 4579 " total alloc undo"); 4580 st->print_raw_cr("--- --------- --------- ------ --------- ------ --------" 4581 " ------- ------- -------"); 4582 } 4583 4584 void 4585 G1ParScanThreadState::print_termination_stats(int i, 4586 outputStream* const st) const 4587 { 4588 const double elapsed_ms = elapsed_time() * 1000.0; 4589 const double s_roots_ms = strong_roots_time() * 1000.0; 4590 const double term_ms = term_time() * 1000.0; 4591 st->print_cr("%3d %9.2f %9.2f %6.2f " 4592 "%9.2f %6.2f " SIZE_FORMAT_W(8) " " 4593 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7), 4594 i, elapsed_ms, s_roots_ms, s_roots_ms * 100 / elapsed_ms, 4595 term_ms, term_ms * 100 / elapsed_ms, term_attempts(), 4596 (alloc_buffer_waste() + undo_waste()) * HeapWordSize / K, 4597 alloc_buffer_waste() * HeapWordSize / K, 4598 undo_waste() * HeapWordSize / K); 4599 } 4600 4601 #ifdef ASSERT 4602 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const { 4603 assert(ref != NULL, "invariant"); 4604 assert(UseCompressedOops, "sanity"); 4605 assert(!has_partial_array_mask(ref), err_msg("ref=" PTR_FORMAT, ref)); 4606 oop p = oopDesc::load_decode_heap_oop(ref); 4607 assert(_g1h->is_in_g1_reserved(p), 4608 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p)); 4609 return true; 4610 } 4611 4612 bool G1ParScanThreadState::verify_ref(oop* ref) const { 4613 assert(ref != NULL, "invariant"); 4614 if (has_partial_array_mask(ref)) { 4615 // Must be in the collection set--it's already been copied. 4616 oop p = clear_partial_array_mask(ref); 4617 assert(_g1h->obj_in_cs(p), 4618 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p)); 4619 } else { 4620 oop p = oopDesc::load_decode_heap_oop(ref); 4621 assert(_g1h->is_in_g1_reserved(p), 4622 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p)); 4623 } 4624 return true; 4625 } 4626 4627 bool G1ParScanThreadState::verify_task(StarTask ref) const { 4628 if (ref.is_narrow()) { 4629 return verify_ref((narrowOop*) ref); 4630 } else { 4631 return verify_ref((oop*) ref); 4632 } 4633 } 4634 #endif // ASSERT 4635 4636 void G1ParScanThreadState::trim_queue() { 4637 assert(_evac_cl != NULL, "not set"); 4638 assert(_evac_failure_cl != NULL, "not set"); 4639 assert(_partial_scan_cl != NULL, "not set"); 4640 4641 StarTask ref; 4642 do { 4643 // Drain the overflow stack first, so other threads can steal. 4644 while (refs()->pop_overflow(ref)) { 4645 deal_with_reference(ref); 4646 } 4647 4648 while (refs()->pop_local(ref)) { 4649 deal_with_reference(ref); 4650 } 4651 } while (!refs()->is_empty()); 4652 } 4653 4654 G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1, 4655 G1ParScanThreadState* par_scan_state) : 4656 _g1(g1), _g1_rem(_g1->g1_rem_set()), _cm(_g1->concurrent_mark()), 4657 _par_scan_state(par_scan_state), 4658 _worker_id(par_scan_state->queue_num()), 4659 _during_initial_mark(_g1->g1_policy()->during_initial_mark_pause()), 4660 _mark_in_progress(_g1->mark_in_progress()) { } 4661 4662 template <G1Barrier barrier, bool do_mark_object> 4663 void G1ParCopyClosure<barrier, do_mark_object>::mark_object(oop obj) { 4664 #ifdef ASSERT 4665 HeapRegion* hr = _g1->heap_region_containing(obj); 4666 assert(hr != NULL, "sanity"); 4667 assert(!hr->in_collection_set(), "should not mark objects in the CSet"); 4668 #endif // ASSERT 4669 4670 // We know that the object is not moving so it's safe to read its size. 4671 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id); 4672 } 4673 4674 template <G1Barrier barrier, bool do_mark_object> 4675 void G1ParCopyClosure<barrier, do_mark_object> 4676 ::mark_forwarded_object(oop from_obj, oop to_obj) { 4677 #ifdef ASSERT 4678 assert(from_obj->is_forwarded(), "from obj should be forwarded"); 4679 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee"); 4680 assert(from_obj != to_obj, "should not be self-forwarded"); 4681 4682 HeapRegion* from_hr = _g1->heap_region_containing(from_obj); 4683 assert(from_hr != NULL, "sanity"); 4684 assert(from_hr->in_collection_set(), "from obj should be in the CSet"); 4685 4686 HeapRegion* to_hr = _g1->heap_region_containing(to_obj); 4687 assert(to_hr != NULL, "sanity"); 4688 assert(!to_hr->in_collection_set(), "should not mark objects in the CSet"); 4689 #endif // ASSERT 4690 4691 // The object might be in the process of being copied by another 4692 // worker so we cannot trust that its to-space image is 4693 // well-formed. So we have to read its size from its from-space 4694 // image which we know should not be changing. 4695 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id); 4696 } 4697 4698 template <G1Barrier barrier, bool do_mark_object> 4699 oop G1ParCopyClosure<barrier, do_mark_object> 4700 ::copy_to_survivor_space(oop old) { 4701 size_t word_sz = old->size(); 4702 HeapRegion* from_region = _g1->heap_region_containing_raw(old); 4703 // +1 to make the -1 indexes valid... 4704 int young_index = from_region->young_index_in_cset()+1; 4705 assert( (from_region->is_young() && young_index > 0) || 4706 (!from_region->is_young() && young_index == 0), "invariant" ); 4707 G1CollectorPolicy* g1p = _g1->g1_policy(); 4708 markOop m = old->mark(); 4709 int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age() 4710 : m->age(); 4711 GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age, 4712 word_sz); 4713 HeapWord* obj_ptr = _par_scan_state->allocate(alloc_purpose, word_sz); 4714 #ifndef PRODUCT 4715 // Should this evacuation fail? 4716 if (_g1->evacuation_should_fail()) { 4717 if (obj_ptr != NULL) { 4718 _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz); 4719 obj_ptr = NULL; 4720 } 4721 } 4722 #endif // !PRODUCT 4723 4724 if (obj_ptr == NULL) { 4725 // This will either forward-to-self, or detect that someone else has 4726 // installed a forwarding pointer. 4727 return _g1->handle_evacuation_failure_par(_par_scan_state, old); 4728 } 4729 4730 oop obj = oop(obj_ptr); 4731 4732 // We're going to allocate linearly, so might as well prefetch ahead. 4733 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes); 4734 4735 oop forward_ptr = old->forward_to_atomic(obj); 4736 if (forward_ptr == NULL) { 4737 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz); 4738 if (g1p->track_object_age(alloc_purpose)) { 4739 // We could simply do obj->incr_age(). However, this causes a 4740 // performance issue. obj->incr_age() will first check whether 4741 // the object has a displaced mark by checking its mark word; 4742 // getting the mark word from the new location of the object 4743 // stalls. So, given that we already have the mark word and we 4744 // are about to install it anyway, it's better to increase the 4745 // age on the mark word, when the object does not have a 4746 // displaced mark word. We're not expecting many objects to have 4747 // a displaced marked word, so that case is not optimized 4748 // further (it could be...) and we simply call obj->incr_age(). 4749 4750 if (m->has_displaced_mark_helper()) { 4751 // in this case, we have to install the mark word first, 4752 // otherwise obj looks to be forwarded (the old mark word, 4753 // which contains the forward pointer, was copied) 4754 obj->set_mark(m); 4755 obj->incr_age(); 4756 } else { 4757 m = m->incr_age(); 4758 obj->set_mark(m); 4759 } 4760 _par_scan_state->age_table()->add(obj, word_sz); 4761 } else { 4762 obj->set_mark(m); 4763 } 4764 4765 size_t* surv_young_words = _par_scan_state->surviving_young_words(); 4766 surv_young_words[young_index] += word_sz; 4767 4768 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) { 4769 // We keep track of the next start index in the length field of 4770 // the to-space object. The actual length can be found in the 4771 // length field of the from-space object. 4772 arrayOop(obj)->set_length(0); 4773 oop* old_p = set_partial_array_mask(old); 4774 _par_scan_state->push_on_queue(old_p); 4775 } else { 4776 // No point in using the slower heap_region_containing() method, 4777 // given that we know obj is in the heap. 4778 _scanner.set_region(_g1->heap_region_containing_raw(obj)); 4779 obj->oop_iterate_backwards(&_scanner); 4780 } 4781 } else { 4782 _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz); 4783 obj = forward_ptr; 4784 } 4785 return obj; 4786 } 4787 4788 template <class T> 4789 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) { 4790 if (_g1->heap_region_containing_raw(new_obj)->is_young()) { 4791 _scanned_klass->record_modified_oops(); 4792 } 4793 } 4794 4795 template <G1Barrier barrier, bool do_mark_object> 4796 template <class T> 4797 void G1ParCopyClosure<barrier, do_mark_object> 4798 ::do_oop_work(T* p) { 4799 oop obj = oopDesc::load_decode_heap_oop(p); 4800 4801 assert(_worker_id == _par_scan_state->queue_num(), "sanity"); 4802 4803 // here the null check is implicit in the cset_fast_test() test 4804 if (_g1->in_cset_fast_test(obj)) { 4805 oop forwardee; 4806 if (obj->is_forwarded()) { 4807 forwardee = obj->forwardee(); 4808 } else { 4809 forwardee = copy_to_survivor_space(obj); 4810 } 4811 assert(forwardee != NULL, "forwardee should not be NULL"); 4812 oopDesc::encode_store_heap_oop(p, forwardee); 4813 if (do_mark_object && forwardee != obj) { 4814 // If the object is self-forwarded we don't need to explicitly 4815 // mark it, the evacuation failure protocol will do so. 4816 mark_forwarded_object(obj, forwardee); 4817 } 4818 4819 if (barrier == G1BarrierKlass) { 4820 do_klass_barrier(p, forwardee); 4821 } 4822 } else { 4823 // The object is not in collection set. If we're a root scanning 4824 // closure during an initial mark pause (i.e. do_mark_object will 4825 // be true) then attempt to mark the object. 4826 if (do_mark_object && _g1->is_in_g1_reserved(obj)) { 4827 mark_object(obj); 4828 } 4829 } 4830 4831 if (barrier == G1BarrierEvac && obj != NULL) { 4832 _par_scan_state->update_rs(_from, p, _worker_id); 4833 } 4834 } 4835 4836 template void G1ParCopyClosure<G1BarrierEvac, false>::do_oop_work(oop* p); 4837 template void G1ParCopyClosure<G1BarrierEvac, false>::do_oop_work(narrowOop* p); 4838 4839 template <class T> void G1ParScanPartialArrayClosure::do_oop_nv(T* p) { 4840 assert(has_partial_array_mask(p), "invariant"); 4841 oop from_obj = clear_partial_array_mask(p); 4842 4843 assert(Universe::heap()->is_in_reserved(from_obj), "must be in heap."); 4844 assert(from_obj->is_objArray(), "must be obj array"); 4845 objArrayOop from_obj_array = objArrayOop(from_obj); 4846 // The from-space object contains the real length. 4847 int length = from_obj_array->length(); 4848 4849 assert(from_obj->is_forwarded(), "must be forwarded"); 4850 oop to_obj = from_obj->forwardee(); 4851 assert(from_obj != to_obj, "should not be chunking self-forwarded objects"); 4852 objArrayOop to_obj_array = objArrayOop(to_obj); 4853 // We keep track of the next start index in the length field of the 4854 // to-space object. 4855 int next_index = to_obj_array->length(); 4856 assert(0 <= next_index && next_index < length, 4857 err_msg("invariant, next index: %d, length: %d", next_index, length)); 4858 4859 int start = next_index; 4860 int end = length; 4861 int remainder = end - start; 4862 // We'll try not to push a range that's smaller than ParGCArrayScanChunk. 4863 if (remainder > 2 * ParGCArrayScanChunk) { 4864 end = start + ParGCArrayScanChunk; 4865 to_obj_array->set_length(end); 4866 // Push the remainder before we process the range in case another 4867 // worker has run out of things to do and can steal it. 4868 oop* from_obj_p = set_partial_array_mask(from_obj); 4869 _par_scan_state->push_on_queue(from_obj_p); 4870 } else { 4871 assert(length == end, "sanity"); 4872 // We'll process the final range for this object. Restore the length 4873 // so that the heap remains parsable in case of evacuation failure. 4874 to_obj_array->set_length(end); 4875 } 4876 _scanner.set_region(_g1->heap_region_containing_raw(to_obj)); 4877 // Process indexes [start,end). It will also process the header 4878 // along with the first chunk (i.e., the chunk with start == 0). 4879 // Note that at this point the length field of to_obj_array is not 4880 // correct given that we are using it to keep track of the next 4881 // start index. oop_iterate_range() (thankfully!) ignores the length 4882 // field and only relies on the start / end parameters. It does 4883 // however return the size of the object which will be incorrect. So 4884 // we have to ignore it even if we wanted to use it. 4885 to_obj_array->oop_iterate_range(&_scanner, start, end); 4886 } 4887 4888 class G1ParEvacuateFollowersClosure : public VoidClosure { 4889 protected: 4890 G1CollectedHeap* _g1h; 4891 G1ParScanThreadState* _par_scan_state; 4892 RefToScanQueueSet* _queues; 4893 ParallelTaskTerminator* _terminator; 4894 4895 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 4896 RefToScanQueueSet* queues() { return _queues; } 4897 ParallelTaskTerminator* terminator() { return _terminator; } 4898 4899 public: 4900 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h, 4901 G1ParScanThreadState* par_scan_state, 4902 RefToScanQueueSet* queues, 4903 ParallelTaskTerminator* terminator) 4904 : _g1h(g1h), _par_scan_state(par_scan_state), 4905 _queues(queues), _terminator(terminator) {} 4906 4907 void do_void(); 4908 4909 private: 4910 inline bool offer_termination(); 4911 }; 4912 4913 bool G1ParEvacuateFollowersClosure::offer_termination() { 4914 G1ParScanThreadState* const pss = par_scan_state(); 4915 pss->start_term_time(); 4916 const bool res = terminator()->offer_termination(); 4917 pss->end_term_time(); 4918 return res; 4919 } 4920 4921 void G1ParEvacuateFollowersClosure::do_void() { 4922 StarTask stolen_task; 4923 G1ParScanThreadState* const pss = par_scan_state(); 4924 pss->trim_queue(); 4925 4926 do { 4927 while (queues()->steal(pss->queue_num(), pss->hash_seed(), stolen_task)) { 4928 assert(pss->verify_task(stolen_task), "sanity"); 4929 if (stolen_task.is_narrow()) { 4930 pss->deal_with_reference((narrowOop*) stolen_task); 4931 } else { 4932 pss->deal_with_reference((oop*) stolen_task); 4933 } 4934 4935 // We've just processed a reference and we might have made 4936 // available new entries on the queues. So we have to make sure 4937 // we drain the queues as necessary. 4938 pss->trim_queue(); 4939 } 4940 } while (!offer_termination()); 4941 4942 pss->retire_alloc_buffers(); 4943 } 4944 4945 class G1KlassScanClosure : public KlassClosure { 4946 G1ParCopyHelper* _closure; 4947 bool _process_only_dirty; 4948 int _count; 4949 public: 4950 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty) 4951 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {} 4952 void do_klass(Klass* klass) { 4953 // If the klass has not been dirtied we know that there's 4954 // no references into the young gen and we can skip it. 4955 if (!_process_only_dirty || klass->has_modified_oops()) { 4956 // Clean the klass since we're going to scavenge all the metadata. 4957 klass->clear_modified_oops(); 4958 4959 // Tell the closure that this klass is the Klass to scavenge 4960 // and is the one to dirty if oops are left pointing into the young gen. 4961 _closure->set_scanned_klass(klass); 4962 4963 klass->oops_do(_closure); 4964 4965 _closure->set_scanned_klass(NULL); 4966 } 4967 _count++; 4968 } 4969 }; 4970 4971 class G1ParTask : public AbstractGangTask { 4972 protected: 4973 G1CollectedHeap* _g1h; 4974 RefToScanQueueSet *_queues; 4975 ParallelTaskTerminator _terminator; 4976 uint _n_workers; 4977 4978 Mutex _stats_lock; 4979 Mutex* stats_lock() { return &_stats_lock; } 4980 4981 size_t getNCards() { 4982 return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1) 4983 / G1BlockOffsetSharedArray::N_bytes; 4984 } 4985 4986 public: 4987 G1ParTask(G1CollectedHeap* g1h, 4988 RefToScanQueueSet *task_queues) 4989 : AbstractGangTask("G1 collection"), 4990 _g1h(g1h), 4991 _queues(task_queues), 4992 _terminator(0, _queues), 4993 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true) 4994 {} 4995 4996 RefToScanQueueSet* queues() { return _queues; } 4997 4998 RefToScanQueue *work_queue(int i) { 4999 return queues()->queue(i); 5000 } 5001 5002 ParallelTaskTerminator* terminator() { return &_terminator; } 5003 5004 virtual void set_for_termination(int active_workers) { 5005 // This task calls set_n_termination() in par_non_clean_card_iterate_work() 5006 // in the young space (_par_seq_tasks) in the G1 heap 5007 // for SequentialSubTasksDone. 5008 // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap 5009 // both of which need setting by set_n_termination(). 5010 _g1h->SharedHeap::set_n_termination(active_workers); 5011 _g1h->set_n_termination(active_workers); 5012 terminator()->reset_for_reuse(active_workers); 5013 _n_workers = active_workers; 5014 } 5015 5016 void work(uint worker_id) { 5017 if (worker_id >= _n_workers) return; // no work needed this round 5018 5019 double start_time_ms = os::elapsedTime() * 1000.0; 5020 _g1h->g1_policy()->phase_times()->record_gc_worker_start_time(worker_id, start_time_ms); 5021 5022 { 5023 ResourceMark rm; 5024 HandleMark hm; 5025 5026 ReferenceProcessor* rp = _g1h->ref_processor_stw(); 5027 5028 G1ParScanThreadState pss(_g1h, worker_id); 5029 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, rp); 5030 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp); 5031 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, rp); 5032 5033 pss.set_evac_closure(&scan_evac_cl); 5034 pss.set_evac_failure_closure(&evac_failure_cl); 5035 pss.set_partial_scan_closure(&partial_scan_cl); 5036 5037 G1ParScanExtRootClosure only_scan_root_cl(_g1h, &pss, rp); 5038 G1ParScanMetadataClosure only_scan_metadata_cl(_g1h, &pss, rp); 5039 5040 G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss, rp); 5041 G1ParScanAndMarkMetadataClosure scan_mark_metadata_cl(_g1h, &pss, rp); 5042 5043 bool only_young = _g1h->g1_policy()->gcs_are_young(); 5044 G1KlassScanClosure scan_mark_klasses_cl_s(&scan_mark_metadata_cl, false); 5045 G1KlassScanClosure only_scan_klasses_cl_s(&only_scan_metadata_cl, only_young); 5046 5047 OopClosure* scan_root_cl = &only_scan_root_cl; 5048 G1KlassScanClosure* scan_klasses_cl = &only_scan_klasses_cl_s; 5049 5050 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5051 // We also need to mark copied objects. 5052 scan_root_cl = &scan_mark_root_cl; 5053 scan_klasses_cl = &scan_mark_klasses_cl_s; 5054 } 5055 5056 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss); 5057 5058 // Don't scan the scavengable methods in the code cache as part 5059 // of strong root scanning. The code roots that point into a 5060 // region in the collection set are scanned when we scan the 5061 // region's RSet. 5062 int so = SharedHeap::SO_AllClasses | SharedHeap::SO_Strings; 5063 5064 pss.start_strong_roots(); 5065 _g1h->g1_process_strong_roots(/* is scavenging */ true, 5066 SharedHeap::ScanningOption(so), 5067 scan_root_cl, 5068 &push_heap_rs_cl, 5069 scan_klasses_cl, 5070 worker_id); 5071 pss.end_strong_roots(); 5072 5073 { 5074 double start = os::elapsedTime(); 5075 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator); 5076 evac.do_void(); 5077 double elapsed_ms = (os::elapsedTime()-start)*1000.0; 5078 double term_ms = pss.term_time()*1000.0; 5079 _g1h->g1_policy()->phase_times()->add_obj_copy_time(worker_id, elapsed_ms-term_ms); 5080 _g1h->g1_policy()->phase_times()->record_termination(worker_id, term_ms, pss.term_attempts()); 5081 } 5082 _g1h->g1_policy()->record_thread_age_table(pss.age_table()); 5083 _g1h->update_surviving_young_words(pss.surviving_young_words()+1); 5084 5085 if (ParallelGCVerbose) { 5086 MutexLocker x(stats_lock()); 5087 pss.print_termination_stats(worker_id); 5088 } 5089 5090 assert(pss.refs()->is_empty(), "should be empty"); 5091 5092 // Close the inner scope so that the ResourceMark and HandleMark 5093 // destructors are executed here and are included as part of the 5094 // "GC Worker Time". 5095 } 5096 5097 double end_time_ms = os::elapsedTime() * 1000.0; 5098 _g1h->g1_policy()->phase_times()->record_gc_worker_end_time(worker_id, end_time_ms); 5099 } 5100 }; 5101 5102 // *** Common G1 Evacuation Stuff 5103 5104 // This method is run in a GC worker. 5105 5106 void 5107 G1CollectedHeap:: 5108 g1_process_strong_roots(bool is_scavenging, 5109 ScanningOption so, 5110 OopClosure* scan_non_heap_roots, 5111 OopsInHeapRegionClosure* scan_rs, 5112 G1KlassScanClosure* scan_klasses, 5113 int worker_i) { 5114 5115 // First scan the strong roots 5116 double ext_roots_start = os::elapsedTime(); 5117 double closure_app_time_sec = 0.0; 5118 5119 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots); 5120 5121 process_strong_roots(false, // no scoping; this is parallel code 5122 so, 5123 &buf_scan_non_heap_roots, 5124 scan_klasses 5125 ); 5126 5127 // Now the CM ref_processor roots. 5128 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) { 5129 // We need to treat the discovered reference lists of the 5130 // concurrent mark ref processor as roots and keep entries 5131 // (which are added by the marking threads) on them live 5132 // until they can be processed at the end of marking. 5133 ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots); 5134 } 5135 5136 // Finish up any enqueued closure apps (attributed as object copy time). 5137 buf_scan_non_heap_roots.done(); 5138 5139 double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds(); 5140 5141 g1_policy()->phase_times()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0); 5142 5143 double ext_root_time_ms = 5144 ((os::elapsedTime() - ext_roots_start) - obj_copy_time_sec) * 1000.0; 5145 5146 g1_policy()->phase_times()->record_ext_root_scan_time(worker_i, ext_root_time_ms); 5147 5148 // During conc marking we have to filter the per-thread SATB buffers 5149 // to make sure we remove any oops into the CSet (which will show up 5150 // as implicitly live). 5151 double satb_filtering_ms = 0.0; 5152 if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers)) { 5153 if (mark_in_progress()) { 5154 double satb_filter_start = os::elapsedTime(); 5155 5156 JavaThread::satb_mark_queue_set().filter_thread_buffers(); 5157 5158 satb_filtering_ms = (os::elapsedTime() - satb_filter_start) * 1000.0; 5159 } 5160 } 5161 g1_policy()->phase_times()->record_satb_filtering_time(worker_i, satb_filtering_ms); 5162 5163 // If this is an initial mark pause, and we're not scanning 5164 // the entire code cache, we need to mark the oops in the 5165 // strong code root lists for the regions that are not in 5166 // the collection set. 5167 // Note all threads participate in this set of root tasks. 5168 double mark_strong_code_roots_ms = 0.0; 5169 if (g1_policy()->during_initial_mark_pause() && !(so & SO_AllCodeCache)) { 5170 double mark_strong_roots_start = os::elapsedTime(); 5171 mark_strong_code_roots(worker_i); 5172 mark_strong_code_roots_ms = (os::elapsedTime() - mark_strong_roots_start) * 1000.0; 5173 } 5174 g1_policy()->phase_times()->record_strong_code_root_mark_time(worker_i, mark_strong_code_roots_ms); 5175 5176 // Now scan the complement of the collection set. 5177 CodeBlobToOopClosure eager_scan_code_roots(scan_non_heap_roots, true /* do_marking */); 5178 g1_rem_set()->oops_into_collection_set_do(scan_rs, &eager_scan_code_roots, worker_i); 5179 5180 _process_strong_tasks->all_tasks_completed(); 5181 } 5182 5183 class G1StringSymbolTableUnlinkTask : public AbstractGangTask { 5184 private: 5185 BoolObjectClosure* _is_alive; 5186 int _initial_string_table_size; 5187 int _initial_symbol_table_size; 5188 5189 bool _process_strings; 5190 int _strings_processed; 5191 int _strings_removed; 5192 5193 bool _process_symbols; 5194 int _symbols_processed; 5195 int _symbols_removed; 5196 5197 bool _do_in_parallel; 5198 public: 5199 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) : 5200 AbstractGangTask("Par String/Symbol table unlink"), _is_alive(is_alive), 5201 _do_in_parallel(G1CollectedHeap::use_parallel_gc_threads()), 5202 _process_strings(process_strings), _strings_processed(0), _strings_removed(0), 5203 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) { 5204 5205 _initial_string_table_size = StringTable::the_table()->table_size(); 5206 _initial_symbol_table_size = SymbolTable::the_table()->table_size(); 5207 if (process_strings) { 5208 StringTable::clear_parallel_claimed_index(); 5209 } 5210 if (process_symbols) { 5211 SymbolTable::clear_parallel_claimed_index(); 5212 } 5213 } 5214 5215 ~G1StringSymbolTableUnlinkTask() { 5216 guarantee(!_process_strings || !_do_in_parallel || StringTable::parallel_claimed_index() >= _initial_string_table_size, 5217 err_msg("claim value "INT32_FORMAT" after unlink less than initial string table size "INT32_FORMAT, 5218 StringTable::parallel_claimed_index(), _initial_string_table_size)); 5219 guarantee(!_process_symbols || !_do_in_parallel || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size, 5220 err_msg("claim value "INT32_FORMAT" after unlink less than initial symbol table size "INT32_FORMAT, 5221 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size)); 5222 } 5223 5224 void work(uint worker_id) { 5225 if (_do_in_parallel) { 5226 int strings_processed = 0; 5227 int strings_removed = 0; 5228 int symbols_processed = 0; 5229 int symbols_removed = 0; 5230 if (_process_strings) { 5231 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed); 5232 Atomic::add(strings_processed, &_strings_processed); 5233 Atomic::add(strings_removed, &_strings_removed); 5234 } 5235 if (_process_symbols) { 5236 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed); 5237 Atomic::add(symbols_processed, &_symbols_processed); 5238 Atomic::add(symbols_removed, &_symbols_removed); 5239 } 5240 } else { 5241 if (_process_strings) { 5242 StringTable::unlink(_is_alive, &_strings_processed, &_strings_removed); 5243 } 5244 if (_process_symbols) { 5245 SymbolTable::unlink(&_symbols_processed, &_symbols_removed); 5246 } 5247 } 5248 } 5249 5250 size_t strings_processed() const { return (size_t)_strings_processed; } 5251 size_t strings_removed() const { return (size_t)_strings_removed; } 5252 5253 size_t symbols_processed() const { return (size_t)_symbols_processed; } 5254 size_t symbols_removed() const { return (size_t)_symbols_removed; } 5255 }; 5256 5257 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive, 5258 bool process_strings, bool process_symbols) { 5259 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ? 5260 _g1h->workers()->active_workers() : 1); 5261 5262 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols); 5263 if (G1CollectedHeap::use_parallel_gc_threads()) { 5264 set_par_threads(n_workers); 5265 workers()->run_task(&g1_unlink_task); 5266 set_par_threads(0); 5267 } else { 5268 g1_unlink_task.work(0); 5269 } 5270 if (G1TraceStringSymbolTableScrubbing) { 5271 gclog_or_tty->print_cr("Cleaned string and symbol table, " 5272 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, " 5273 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed", 5274 g1_unlink_task.strings_processed(), g1_unlink_task.strings_removed(), 5275 g1_unlink_task.symbols_processed(), g1_unlink_task.symbols_removed()); 5276 } 5277 } 5278 5279 // Weak Reference Processing support 5280 5281 // An always "is_alive" closure that is used to preserve referents. 5282 // If the object is non-null then it's alive. Used in the preservation 5283 // of referent objects that are pointed to by reference objects 5284 // discovered by the CM ref processor. 5285 class G1AlwaysAliveClosure: public BoolObjectClosure { 5286 G1CollectedHeap* _g1; 5287 public: 5288 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 5289 bool do_object_b(oop p) { 5290 if (p != NULL) { 5291 return true; 5292 } 5293 return false; 5294 } 5295 }; 5296 5297 bool G1STWIsAliveClosure::do_object_b(oop p) { 5298 // An object is reachable if it is outside the collection set, 5299 // or is inside and copied. 5300 return !_g1->obj_in_cs(p) || p->is_forwarded(); 5301 } 5302 5303 // Non Copying Keep Alive closure 5304 class G1KeepAliveClosure: public OopClosure { 5305 G1CollectedHeap* _g1; 5306 public: 5307 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 5308 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } 5309 void do_oop( oop* p) { 5310 oop obj = *p; 5311 5312 if (_g1->obj_in_cs(obj)) { 5313 assert( obj->is_forwarded(), "invariant" ); 5314 *p = obj->forwardee(); 5315 } 5316 } 5317 }; 5318 5319 // Copying Keep Alive closure - can be called from both 5320 // serial and parallel code as long as different worker 5321 // threads utilize different G1ParScanThreadState instances 5322 // and different queues. 5323 5324 class G1CopyingKeepAliveClosure: public OopClosure { 5325 G1CollectedHeap* _g1h; 5326 OopClosure* _copy_non_heap_obj_cl; 5327 OopsInHeapRegionClosure* _copy_metadata_obj_cl; 5328 G1ParScanThreadState* _par_scan_state; 5329 5330 public: 5331 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, 5332 OopClosure* non_heap_obj_cl, 5333 OopsInHeapRegionClosure* metadata_obj_cl, 5334 G1ParScanThreadState* pss): 5335 _g1h(g1h), 5336 _copy_non_heap_obj_cl(non_heap_obj_cl), 5337 _copy_metadata_obj_cl(metadata_obj_cl), 5338 _par_scan_state(pss) 5339 {} 5340 5341 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 5342 virtual void do_oop( oop* p) { do_oop_work(p); } 5343 5344 template <class T> void do_oop_work(T* p) { 5345 oop obj = oopDesc::load_decode_heap_oop(p); 5346 5347 if (_g1h->obj_in_cs(obj)) { 5348 // If the referent object has been forwarded (either copied 5349 // to a new location or to itself in the event of an 5350 // evacuation failure) then we need to update the reference 5351 // field and, if both reference and referent are in the G1 5352 // heap, update the RSet for the referent. 5353 // 5354 // If the referent has not been forwarded then we have to keep 5355 // it alive by policy. Therefore we have copy the referent. 5356 // 5357 // If the reference field is in the G1 heap then we can push 5358 // on the PSS queue. When the queue is drained (after each 5359 // phase of reference processing) the object and it's followers 5360 // will be copied, the reference field set to point to the 5361 // new location, and the RSet updated. Otherwise we need to 5362 // use the the non-heap or metadata closures directly to copy 5363 // the referent object and update the pointer, while avoiding 5364 // updating the RSet. 5365 5366 if (_g1h->is_in_g1_reserved(p)) { 5367 _par_scan_state->push_on_queue(p); 5368 } else { 5369 assert(!ClassLoaderDataGraph::contains((address)p), 5370 err_msg("Otherwise need to call _copy_metadata_obj_cl->do_oop(p) " 5371 PTR_FORMAT, p)); 5372 _copy_non_heap_obj_cl->do_oop(p); 5373 } 5374 } 5375 } 5376 }; 5377 5378 // Serial drain queue closure. Called as the 'complete_gc' 5379 // closure for each discovered list in some of the 5380 // reference processing phases. 5381 5382 class G1STWDrainQueueClosure: public VoidClosure { 5383 protected: 5384 G1CollectedHeap* _g1h; 5385 G1ParScanThreadState* _par_scan_state; 5386 5387 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 5388 5389 public: 5390 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : 5391 _g1h(g1h), 5392 _par_scan_state(pss) 5393 { } 5394 5395 void do_void() { 5396 G1ParScanThreadState* const pss = par_scan_state(); 5397 pss->trim_queue(); 5398 } 5399 }; 5400 5401 // Parallel Reference Processing closures 5402 5403 // Implementation of AbstractRefProcTaskExecutor for parallel reference 5404 // processing during G1 evacuation pauses. 5405 5406 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 5407 private: 5408 G1CollectedHeap* _g1h; 5409 RefToScanQueueSet* _queues; 5410 FlexibleWorkGang* _workers; 5411 int _active_workers; 5412 5413 public: 5414 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, 5415 FlexibleWorkGang* workers, 5416 RefToScanQueueSet *task_queues, 5417 int n_workers) : 5418 _g1h(g1h), 5419 _queues(task_queues), 5420 _workers(workers), 5421 _active_workers(n_workers) 5422 { 5423 assert(n_workers > 0, "shouldn't call this otherwise"); 5424 } 5425 5426 // Executes the given task using concurrent marking worker threads. 5427 virtual void execute(ProcessTask& task); 5428 virtual void execute(EnqueueTask& task); 5429 }; 5430 5431 // Gang task for possibly parallel reference processing 5432 5433 class G1STWRefProcTaskProxy: public AbstractGangTask { 5434 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 5435 ProcessTask& _proc_task; 5436 G1CollectedHeap* _g1h; 5437 RefToScanQueueSet *_task_queues; 5438 ParallelTaskTerminator* _terminator; 5439 5440 public: 5441 G1STWRefProcTaskProxy(ProcessTask& proc_task, 5442 G1CollectedHeap* g1h, 5443 RefToScanQueueSet *task_queues, 5444 ParallelTaskTerminator* terminator) : 5445 AbstractGangTask("Process reference objects in parallel"), 5446 _proc_task(proc_task), 5447 _g1h(g1h), 5448 _task_queues(task_queues), 5449 _terminator(terminator) 5450 {} 5451 5452 virtual void work(uint worker_id) { 5453 // The reference processing task executed by a single worker. 5454 ResourceMark rm; 5455 HandleMark hm; 5456 5457 G1STWIsAliveClosure is_alive(_g1h); 5458 5459 G1ParScanThreadState pss(_g1h, worker_id); 5460 5461 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, NULL); 5462 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL); 5463 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, NULL); 5464 5465 pss.set_evac_closure(&scan_evac_cl); 5466 pss.set_evac_failure_closure(&evac_failure_cl); 5467 pss.set_partial_scan_closure(&partial_scan_cl); 5468 5469 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL); 5470 G1ParScanMetadataClosure only_copy_metadata_cl(_g1h, &pss, NULL); 5471 5472 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL); 5473 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL); 5474 5475 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5476 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl; 5477 5478 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5479 // We also need to mark copied objects. 5480 copy_non_heap_cl = ©_mark_non_heap_cl; 5481 copy_metadata_cl = ©_mark_metadata_cl; 5482 } 5483 5484 // Keep alive closure. 5485 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss); 5486 5487 // Complete GC closure 5488 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator); 5489 5490 // Call the reference processing task's work routine. 5491 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); 5492 5493 // Note we cannot assert that the refs array is empty here as not all 5494 // of the processing tasks (specifically phase2 - pp2_work) execute 5495 // the complete_gc closure (which ordinarily would drain the queue) so 5496 // the queue may not be empty. 5497 } 5498 }; 5499 5500 // Driver routine for parallel reference processing. 5501 // Creates an instance of the ref processing gang 5502 // task and has the worker threads execute it. 5503 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) { 5504 assert(_workers != NULL, "Need parallel worker threads."); 5505 5506 ParallelTaskTerminator terminator(_active_workers, _queues); 5507 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator); 5508 5509 _g1h->set_par_threads(_active_workers); 5510 _workers->run_task(&proc_task_proxy); 5511 _g1h->set_par_threads(0); 5512 } 5513 5514 // Gang task for parallel reference enqueueing. 5515 5516 class G1STWRefEnqueueTaskProxy: public AbstractGangTask { 5517 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; 5518 EnqueueTask& _enq_task; 5519 5520 public: 5521 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) : 5522 AbstractGangTask("Enqueue reference objects in parallel"), 5523 _enq_task(enq_task) 5524 { } 5525 5526 virtual void work(uint worker_id) { 5527 _enq_task.work(worker_id); 5528 } 5529 }; 5530 5531 // Driver routine for parallel reference enqueueing. 5532 // Creates an instance of the ref enqueueing gang 5533 // task and has the worker threads execute it. 5534 5535 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) { 5536 assert(_workers != NULL, "Need parallel worker threads."); 5537 5538 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task); 5539 5540 _g1h->set_par_threads(_active_workers); 5541 _workers->run_task(&enq_task_proxy); 5542 _g1h->set_par_threads(0); 5543 } 5544 5545 // End of weak reference support closures 5546 5547 // Abstract task used to preserve (i.e. copy) any referent objects 5548 // that are in the collection set and are pointed to by reference 5549 // objects discovered by the CM ref processor. 5550 5551 class G1ParPreserveCMReferentsTask: public AbstractGangTask { 5552 protected: 5553 G1CollectedHeap* _g1h; 5554 RefToScanQueueSet *_queues; 5555 ParallelTaskTerminator _terminator; 5556 uint _n_workers; 5557 5558 public: 5559 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) : 5560 AbstractGangTask("ParPreserveCMReferents"), 5561 _g1h(g1h), 5562 _queues(task_queues), 5563 _terminator(workers, _queues), 5564 _n_workers(workers) 5565 { } 5566 5567 void work(uint worker_id) { 5568 ResourceMark rm; 5569 HandleMark hm; 5570 5571 G1ParScanThreadState pss(_g1h, worker_id); 5572 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, NULL); 5573 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL); 5574 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, NULL); 5575 5576 pss.set_evac_closure(&scan_evac_cl); 5577 pss.set_evac_failure_closure(&evac_failure_cl); 5578 pss.set_partial_scan_closure(&partial_scan_cl); 5579 5580 assert(pss.refs()->is_empty(), "both queue and overflow should be empty"); 5581 5582 5583 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL); 5584 G1ParScanMetadataClosure only_copy_metadata_cl(_g1h, &pss, NULL); 5585 5586 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL); 5587 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL); 5588 5589 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5590 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl; 5591 5592 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5593 // We also need to mark copied objects. 5594 copy_non_heap_cl = ©_mark_non_heap_cl; 5595 copy_metadata_cl = ©_mark_metadata_cl; 5596 } 5597 5598 // Is alive closure 5599 G1AlwaysAliveClosure always_alive(_g1h); 5600 5601 // Copying keep alive closure. Applied to referent objects that need 5602 // to be copied. 5603 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss); 5604 5605 ReferenceProcessor* rp = _g1h->ref_processor_cm(); 5606 5607 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q(); 5608 uint stride = MIN2(MAX2(_n_workers, 1U), limit); 5609 5610 // limit is set using max_num_q() - which was set using ParallelGCThreads. 5611 // So this must be true - but assert just in case someone decides to 5612 // change the worker ids. 5613 assert(0 <= worker_id && worker_id < limit, "sanity"); 5614 assert(!rp->discovery_is_atomic(), "check this code"); 5615 5616 // Select discovered lists [i, i+stride, i+2*stride,...,limit) 5617 for (uint idx = worker_id; idx < limit; idx += stride) { 5618 DiscoveredList& ref_list = rp->discovered_refs()[idx]; 5619 5620 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive); 5621 while (iter.has_next()) { 5622 // Since discovery is not atomic for the CM ref processor, we 5623 // can see some null referent objects. 5624 iter.load_ptrs(DEBUG_ONLY(true)); 5625 oop ref = iter.obj(); 5626 5627 // This will filter nulls. 5628 if (iter.is_referent_alive()) { 5629 iter.make_referent_alive(); 5630 } 5631 iter.move_to_next(); 5632 } 5633 } 5634 5635 // Drain the queue - which may cause stealing 5636 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator); 5637 drain_queue.do_void(); 5638 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure 5639 assert(pss.refs()->is_empty(), "should be"); 5640 } 5641 }; 5642 5643 // Weak Reference processing during an evacuation pause (part 1). 5644 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) { 5645 double ref_proc_start = os::elapsedTime(); 5646 5647 ReferenceProcessor* rp = _ref_processor_stw; 5648 assert(rp->discovery_enabled(), "should have been enabled"); 5649 5650 // Any reference objects, in the collection set, that were 'discovered' 5651 // by the CM ref processor should have already been copied (either by 5652 // applying the external root copy closure to the discovered lists, or 5653 // by following an RSet entry). 5654 // 5655 // But some of the referents, that are in the collection set, that these 5656 // reference objects point to may not have been copied: the STW ref 5657 // processor would have seen that the reference object had already 5658 // been 'discovered' and would have skipped discovering the reference, 5659 // but would not have treated the reference object as a regular oop. 5660 // As a result the copy closure would not have been applied to the 5661 // referent object. 5662 // 5663 // We need to explicitly copy these referent objects - the references 5664 // will be processed at the end of remarking. 5665 // 5666 // We also need to do this copying before we process the reference 5667 // objects discovered by the STW ref processor in case one of these 5668 // referents points to another object which is also referenced by an 5669 // object discovered by the STW ref processor. 5670 5671 assert(!G1CollectedHeap::use_parallel_gc_threads() || 5672 no_of_gc_workers == workers()->active_workers(), 5673 "Need to reset active GC workers"); 5674 5675 set_par_threads(no_of_gc_workers); 5676 G1ParPreserveCMReferentsTask keep_cm_referents(this, 5677 no_of_gc_workers, 5678 _task_queues); 5679 5680 if (G1CollectedHeap::use_parallel_gc_threads()) { 5681 workers()->run_task(&keep_cm_referents); 5682 } else { 5683 keep_cm_referents.work(0); 5684 } 5685 5686 set_par_threads(0); 5687 5688 // Closure to test whether a referent is alive. 5689 G1STWIsAliveClosure is_alive(this); 5690 5691 // Even when parallel reference processing is enabled, the processing 5692 // of JNI refs is serial and performed serially by the current thread 5693 // rather than by a worker. The following PSS will be used for processing 5694 // JNI refs. 5695 5696 // Use only a single queue for this PSS. 5697 G1ParScanThreadState pss(this, 0); 5698 5699 // We do not embed a reference processor in the copying/scanning 5700 // closures while we're actually processing the discovered 5701 // reference objects. 5702 G1ParScanHeapEvacClosure scan_evac_cl(this, &pss, NULL); 5703 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL); 5704 G1ParScanPartialArrayClosure partial_scan_cl(this, &pss, NULL); 5705 5706 pss.set_evac_closure(&scan_evac_cl); 5707 pss.set_evac_failure_closure(&evac_failure_cl); 5708 pss.set_partial_scan_closure(&partial_scan_cl); 5709 5710 assert(pss.refs()->is_empty(), "pre-condition"); 5711 5712 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL); 5713 G1ParScanMetadataClosure only_copy_metadata_cl(this, &pss, NULL); 5714 5715 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL); 5716 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(this, &pss, NULL); 5717 5718 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5719 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl; 5720 5721 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5722 // We also need to mark copied objects. 5723 copy_non_heap_cl = ©_mark_non_heap_cl; 5724 copy_metadata_cl = ©_mark_metadata_cl; 5725 } 5726 5727 // Keep alive closure. 5728 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, copy_metadata_cl, &pss); 5729 5730 // Serial Complete GC closure 5731 G1STWDrainQueueClosure drain_queue(this, &pss); 5732 5733 // Setup the soft refs policy... 5734 rp->setup_policy(false); 5735 5736 ReferenceProcessorStats stats; 5737 if (!rp->processing_is_mt()) { 5738 // Serial reference processing... 5739 stats = rp->process_discovered_references(&is_alive, 5740 &keep_alive, 5741 &drain_queue, 5742 NULL, 5743 _gc_timer_stw); 5744 } else { 5745 // Parallel reference processing 5746 assert(rp->num_q() == no_of_gc_workers, "sanity"); 5747 assert(no_of_gc_workers <= rp->max_num_q(), "sanity"); 5748 5749 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers); 5750 stats = rp->process_discovered_references(&is_alive, 5751 &keep_alive, 5752 &drain_queue, 5753 &par_task_executor, 5754 _gc_timer_stw); 5755 } 5756 5757 _gc_tracer_stw->report_gc_reference_stats(stats); 5758 // We have completed copying any necessary live referent objects 5759 // (that were not copied during the actual pause) so we can 5760 // retire any active alloc buffers 5761 pss.retire_alloc_buffers(); 5762 assert(pss.refs()->is_empty(), "both queue and overflow should be empty"); 5763 5764 double ref_proc_time = os::elapsedTime() - ref_proc_start; 5765 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 5766 } 5767 5768 // Weak Reference processing during an evacuation pause (part 2). 5769 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) { 5770 double ref_enq_start = os::elapsedTime(); 5771 5772 ReferenceProcessor* rp = _ref_processor_stw; 5773 assert(!rp->discovery_enabled(), "should have been disabled as part of processing"); 5774 5775 // Now enqueue any remaining on the discovered lists on to 5776 // the pending list. 5777 if (!rp->processing_is_mt()) { 5778 // Serial reference processing... 5779 rp->enqueue_discovered_references(); 5780 } else { 5781 // Parallel reference enqueueing 5782 5783 assert(no_of_gc_workers == workers()->active_workers(), 5784 "Need to reset active workers"); 5785 assert(rp->num_q() == no_of_gc_workers, "sanity"); 5786 assert(no_of_gc_workers <= rp->max_num_q(), "sanity"); 5787 5788 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers); 5789 rp->enqueue_discovered_references(&par_task_executor); 5790 } 5791 5792 rp->verify_no_references_recorded(); 5793 assert(!rp->discovery_enabled(), "should have been disabled"); 5794 5795 // FIXME 5796 // CM's reference processing also cleans up the string and symbol tables. 5797 // Should we do that here also? We could, but it is a serial operation 5798 // and could significantly increase the pause time. 5799 5800 double ref_enq_time = os::elapsedTime() - ref_enq_start; 5801 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0); 5802 } 5803 5804 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) { 5805 _expand_heap_after_alloc_failure = true; 5806 _evacuation_failed = false; 5807 5808 // Should G1EvacuationFailureALot be in effect for this GC? 5809 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) 5810 5811 g1_rem_set()->prepare_for_oops_into_collection_set_do(); 5812 5813 // Disable the hot card cache. 5814 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 5815 hot_card_cache->reset_hot_cache_claimed_index(); 5816 hot_card_cache->set_use_cache(false); 5817 5818 uint n_workers; 5819 if (G1CollectedHeap::use_parallel_gc_threads()) { 5820 n_workers = 5821 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 5822 workers()->active_workers(), 5823 Threads::number_of_non_daemon_threads()); 5824 assert(UseDynamicNumberOfGCThreads || 5825 n_workers == workers()->total_workers(), 5826 "If not dynamic should be using all the workers"); 5827 workers()->set_active_workers(n_workers); 5828 set_par_threads(n_workers); 5829 } else { 5830 assert(n_par_threads() == 0, 5831 "Should be the original non-parallel value"); 5832 n_workers = 1; 5833 } 5834 5835 G1ParTask g1_par_task(this, _task_queues); 5836 5837 init_for_evac_failure(NULL); 5838 5839 rem_set()->prepare_for_younger_refs_iterate(true); 5840 5841 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty"); 5842 double start_par_time_sec = os::elapsedTime(); 5843 double end_par_time_sec; 5844 5845 { 5846 StrongRootsScope srs(this); 5847 5848 if (G1CollectedHeap::use_parallel_gc_threads()) { 5849 // The individual threads will set their evac-failure closures. 5850 if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr(); 5851 // These tasks use ShareHeap::_process_strong_tasks 5852 assert(UseDynamicNumberOfGCThreads || 5853 workers()->active_workers() == workers()->total_workers(), 5854 "If not dynamic should be using all the workers"); 5855 workers()->run_task(&g1_par_task); 5856 } else { 5857 g1_par_task.set_for_termination(n_workers); 5858 g1_par_task.work(0); 5859 } 5860 end_par_time_sec = os::elapsedTime(); 5861 5862 // Closing the inner scope will execute the destructor 5863 // for the StrongRootsScope object. We record the current 5864 // elapsed time before closing the scope so that time 5865 // taken for the SRS destructor is NOT included in the 5866 // reported parallel time. 5867 } 5868 5869 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0; 5870 g1_policy()->phase_times()->record_par_time(par_time_ms); 5871 5872 double code_root_fixup_time_ms = 5873 (os::elapsedTime() - end_par_time_sec) * 1000.0; 5874 g1_policy()->phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms); 5875 5876 set_par_threads(0); 5877 5878 // Process any discovered reference objects - we have 5879 // to do this _before_ we retire the GC alloc regions 5880 // as we may have to copy some 'reachable' referent 5881 // objects (and their reachable sub-graphs) that were 5882 // not copied during the pause. 5883 process_discovered_references(n_workers); 5884 5885 // Weak root processing. 5886 { 5887 G1STWIsAliveClosure is_alive(this); 5888 G1KeepAliveClosure keep_alive(this); 5889 JNIHandles::weak_oops_do(&is_alive, &keep_alive); 5890 } 5891 5892 release_gc_alloc_regions(n_workers, evacuation_info); 5893 g1_rem_set()->cleanup_after_oops_into_collection_set_do(); 5894 5895 // Reset and re-enable the hot card cache. 5896 // Note the counts for the cards in the regions in the 5897 // collection set are reset when the collection set is freed. 5898 hot_card_cache->reset_hot_cache(); 5899 hot_card_cache->set_use_cache(true); 5900 5901 // Migrate the strong code roots attached to each region in 5902 // the collection set. Ideally we would like to do this 5903 // after we have finished the scanning/evacuation of the 5904 // strong code roots for a particular heap region. 5905 migrate_strong_code_roots(); 5906 5907 purge_code_root_memory(); 5908 5909 if (g1_policy()->during_initial_mark_pause()) { 5910 // Reset the claim values set during marking the strong code roots 5911 reset_heap_region_claim_values(); 5912 } 5913 5914 finalize_for_evac_failure(); 5915 5916 if (evacuation_failed()) { 5917 remove_self_forwarding_pointers(); 5918 5919 // Reset the G1EvacuationFailureALot counters and flags 5920 // Note: the values are reset only when an actual 5921 // evacuation failure occurs. 5922 NOT_PRODUCT(reset_evacuation_should_fail();) 5923 } 5924 5925 // Enqueue any remaining references remaining on the STW 5926 // reference processor's discovered lists. We need to do 5927 // this after the card table is cleaned (and verified) as 5928 // the act of enqueueing entries on to the pending list 5929 // will log these updates (and dirty their associated 5930 // cards). We need these updates logged to update any 5931 // RSets. 5932 enqueue_discovered_references(n_workers); 5933 5934 if (G1DeferredRSUpdate) { 5935 RedirtyLoggedCardTableEntryFastClosure redirty; 5936 dirty_card_queue_set().set_closure(&redirty); 5937 dirty_card_queue_set().apply_closure_to_all_completed_buffers(); 5938 5939 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set(); 5940 dcq.merge_bufferlists(&dirty_card_queue_set()); 5941 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed"); 5942 } 5943 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 5944 } 5945 5946 void G1CollectedHeap::free_region_if_empty(HeapRegion* hr, 5947 size_t* pre_used, 5948 FreeRegionList* free_list, 5949 OldRegionSet* old_proxy_set, 5950 HumongousRegionSet* humongous_proxy_set, 5951 HRRSCleanupTask* hrrs_cleanup_task, 5952 bool par) { 5953 if (hr->used() > 0 && hr->max_live_bytes() == 0 && !hr->is_young()) { 5954 if (hr->isHumongous()) { 5955 assert(hr->startsHumongous(), "we should only see starts humongous"); 5956 free_humongous_region(hr, pre_used, free_list, humongous_proxy_set, par); 5957 } else { 5958 _old_set.remove_with_proxy(hr, old_proxy_set); 5959 free_region(hr, pre_used, free_list, par); 5960 } 5961 } else { 5962 hr->rem_set()->do_cleanup_work(hrrs_cleanup_task); 5963 } 5964 } 5965 5966 void G1CollectedHeap::free_region(HeapRegion* hr, 5967 size_t* pre_used, 5968 FreeRegionList* free_list, 5969 bool par) { 5970 assert(!hr->isHumongous(), "this is only for non-humongous regions"); 5971 assert(!hr->is_empty(), "the region should not be empty"); 5972 assert(free_list != NULL, "pre-condition"); 5973 5974 // Clear the card counts for this region. 5975 // Note: we only need to do this if the region is not young 5976 // (since we don't refine cards in young regions). 5977 if (!hr->is_young()) { 5978 _cg1r->hot_card_cache()->reset_card_counts(hr); 5979 } 5980 *pre_used += hr->used(); 5981 hr->hr_clear(par, true /* clear_space */); 5982 free_list->add_as_head(hr); 5983 } 5984 5985 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 5986 size_t* pre_used, 5987 FreeRegionList* free_list, 5988 HumongousRegionSet* humongous_proxy_set, 5989 bool par) { 5990 assert(hr->startsHumongous(), "this is only for starts humongous regions"); 5991 assert(free_list != NULL, "pre-condition"); 5992 assert(humongous_proxy_set != NULL, "pre-condition"); 5993 5994 size_t hr_used = hr->used(); 5995 size_t hr_capacity = hr->capacity(); 5996 size_t hr_pre_used = 0; 5997 _humongous_set.remove_with_proxy(hr, humongous_proxy_set); 5998 // We need to read this before we make the region non-humongous, 5999 // otherwise the information will be gone. 6000 uint last_index = hr->last_hc_index(); 6001 hr->set_notHumongous(); 6002 free_region(hr, &hr_pre_used, free_list, par); 6003 6004 uint i = hr->hrs_index() + 1; 6005 while (i < last_index) { 6006 HeapRegion* curr_hr = region_at(i); 6007 assert(curr_hr->continuesHumongous(), "invariant"); 6008 curr_hr->set_notHumongous(); 6009 free_region(curr_hr, &hr_pre_used, free_list, par); 6010 i += 1; 6011 } 6012 assert(hr_pre_used == hr_used, 6013 err_msg("hr_pre_used: "SIZE_FORMAT" and hr_used: "SIZE_FORMAT" " 6014 "should be the same", hr_pre_used, hr_used)); 6015 *pre_used += hr_pre_used; 6016 } 6017 6018 void G1CollectedHeap::update_sets_after_freeing_regions(size_t pre_used, 6019 FreeRegionList* free_list, 6020 OldRegionSet* old_proxy_set, 6021 HumongousRegionSet* humongous_proxy_set, 6022 bool par) { 6023 if (pre_used > 0) { 6024 Mutex* lock = (par) ? ParGCRareEvent_lock : NULL; 6025 MutexLockerEx x(lock, Mutex::_no_safepoint_check_flag); 6026 assert(_summary_bytes_used >= pre_used, 6027 err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" " 6028 "should be >= pre_used: "SIZE_FORMAT, 6029 _summary_bytes_used, pre_used)); 6030 _summary_bytes_used -= pre_used; 6031 } 6032 if (free_list != NULL && !free_list->is_empty()) { 6033 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag); 6034 _free_list.add_as_head(free_list); 6035 } 6036 if (old_proxy_set != NULL && !old_proxy_set->is_empty()) { 6037 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 6038 _old_set.update_from_proxy(old_proxy_set); 6039 } 6040 if (humongous_proxy_set != NULL && !humongous_proxy_set->is_empty()) { 6041 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 6042 _humongous_set.update_from_proxy(humongous_proxy_set); 6043 } 6044 } 6045 6046 class G1ParCleanupCTTask : public AbstractGangTask { 6047 G1SATBCardTableModRefBS* _ct_bs; 6048 G1CollectedHeap* _g1h; 6049 HeapRegion* volatile _su_head; 6050 public: 6051 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs, 6052 G1CollectedHeap* g1h) : 6053 AbstractGangTask("G1 Par Cleanup CT Task"), 6054 _ct_bs(ct_bs), _g1h(g1h) { } 6055 6056 void work(uint worker_id) { 6057 HeapRegion* r; 6058 while (r = _g1h->pop_dirty_cards_region()) { 6059 clear_cards(r); 6060 } 6061 } 6062 6063 void clear_cards(HeapRegion* r) { 6064 // Cards of the survivors should have already been dirtied. 6065 if (!r->is_survivor()) { 6066 _ct_bs->clear(MemRegion(r->bottom(), r->end())); 6067 } 6068 } 6069 }; 6070 6071 #ifndef PRODUCT 6072 class G1VerifyCardTableCleanup: public HeapRegionClosure { 6073 G1CollectedHeap* _g1h; 6074 G1SATBCardTableModRefBS* _ct_bs; 6075 public: 6076 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs) 6077 : _g1h(g1h), _ct_bs(ct_bs) { } 6078 virtual bool doHeapRegion(HeapRegion* r) { 6079 if (r->is_survivor()) { 6080 _g1h->verify_dirty_region(r); 6081 } else { 6082 _g1h->verify_not_dirty_region(r); 6083 } 6084 return false; 6085 } 6086 }; 6087 6088 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) { 6089 // All of the region should be clean. 6090 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 6091 MemRegion mr(hr->bottom(), hr->end()); 6092 ct_bs->verify_not_dirty_region(mr); 6093 } 6094 6095 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) { 6096 // We cannot guarantee that [bottom(),end()] is dirty. Threads 6097 // dirty allocated blocks as they allocate them. The thread that 6098 // retires each region and replaces it with a new one will do a 6099 // maximal allocation to fill in [pre_dummy_top(),end()] but will 6100 // not dirty that area (one less thing to have to do while holding 6101 // a lock). So we can only verify that [bottom(),pre_dummy_top()] 6102 // is dirty. 6103 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 6104 MemRegion mr(hr->bottom(), hr->pre_dummy_top()); 6105 if (hr->is_young()) { 6106 ct_bs->verify_g1_young_region(mr); 6107 } else { 6108 ct_bs->verify_dirty_region(mr); 6109 } 6110 } 6111 6112 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) { 6113 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 6114 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) { 6115 verify_dirty_region(hr); 6116 } 6117 } 6118 6119 void G1CollectedHeap::verify_dirty_young_regions() { 6120 verify_dirty_young_list(_young_list->first_region()); 6121 } 6122 #endif 6123 6124 void G1CollectedHeap::cleanUpCardTable() { 6125 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 6126 double start = os::elapsedTime(); 6127 6128 { 6129 // Iterate over the dirty cards region list. 6130 G1ParCleanupCTTask cleanup_task(ct_bs, this); 6131 6132 if (G1CollectedHeap::use_parallel_gc_threads()) { 6133 set_par_threads(); 6134 workers()->run_task(&cleanup_task); 6135 set_par_threads(0); 6136 } else { 6137 while (_dirty_cards_region_list) { 6138 HeapRegion* r = _dirty_cards_region_list; 6139 cleanup_task.clear_cards(r); 6140 _dirty_cards_region_list = r->get_next_dirty_cards_region(); 6141 if (_dirty_cards_region_list == r) { 6142 // The last region. 6143 _dirty_cards_region_list = NULL; 6144 } 6145 r->set_next_dirty_cards_region(NULL); 6146 } 6147 } 6148 #ifndef PRODUCT 6149 if (G1VerifyCTCleanup || VerifyAfterGC) { 6150 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs); 6151 heap_region_iterate(&cleanup_verifier); 6152 } 6153 #endif 6154 } 6155 6156 double elapsed = os::elapsedTime() - start; 6157 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0); 6158 } 6159 6160 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) { 6161 size_t pre_used = 0; 6162 FreeRegionList local_free_list("Local List for CSet Freeing"); 6163 6164 double young_time_ms = 0.0; 6165 double non_young_time_ms = 0.0; 6166 6167 // Since the collection set is a superset of the the young list, 6168 // all we need to do to clear the young list is clear its 6169 // head and length, and unlink any young regions in the code below 6170 _young_list->clear(); 6171 6172 G1CollectorPolicy* policy = g1_policy(); 6173 6174 double start_sec = os::elapsedTime(); 6175 bool non_young = true; 6176 6177 HeapRegion* cur = cs_head; 6178 int age_bound = -1; 6179 size_t rs_lengths = 0; 6180 6181 while (cur != NULL) { 6182 assert(!is_on_master_free_list(cur), "sanity"); 6183 if (non_young) { 6184 if (cur->is_young()) { 6185 double end_sec = os::elapsedTime(); 6186 double elapsed_ms = (end_sec - start_sec) * 1000.0; 6187 non_young_time_ms += elapsed_ms; 6188 6189 start_sec = os::elapsedTime(); 6190 non_young = false; 6191 } 6192 } else { 6193 if (!cur->is_young()) { 6194 double end_sec = os::elapsedTime(); 6195 double elapsed_ms = (end_sec - start_sec) * 1000.0; 6196 young_time_ms += elapsed_ms; 6197 6198 start_sec = os::elapsedTime(); 6199 non_young = true; 6200 } 6201 } 6202 6203 rs_lengths += cur->rem_set()->occupied(); 6204 6205 HeapRegion* next = cur->next_in_collection_set(); 6206 assert(cur->in_collection_set(), "bad CS"); 6207 cur->set_next_in_collection_set(NULL); 6208 cur->set_in_collection_set(false); 6209 6210 if (cur->is_young()) { 6211 int index = cur->young_index_in_cset(); 6212 assert(index != -1, "invariant"); 6213 assert((uint) index < policy->young_cset_region_length(), "invariant"); 6214 size_t words_survived = _surviving_young_words[index]; 6215 cur->record_surv_words_in_group(words_survived); 6216 6217 // At this point the we have 'popped' cur from the collection set 6218 // (linked via next_in_collection_set()) but it is still in the 6219 // young list (linked via next_young_region()). Clear the 6220 // _next_young_region field. 6221 cur->set_next_young_region(NULL); 6222 } else { 6223 int index = cur->young_index_in_cset(); 6224 assert(index == -1, "invariant"); 6225 } 6226 6227 assert( (cur->is_young() && cur->young_index_in_cset() > -1) || 6228 (!cur->is_young() && cur->young_index_in_cset() == -1), 6229 "invariant" ); 6230 6231 if (!cur->evacuation_failed()) { 6232 MemRegion used_mr = cur->used_region(); 6233 6234 // And the region is empty. 6235 assert(!used_mr.is_empty(), "Should not have empty regions in a CS."); 6236 free_region(cur, &pre_used, &local_free_list, false /* par */); 6237 } else { 6238 cur->uninstall_surv_rate_group(); 6239 if (cur->is_young()) { 6240 cur->set_young_index_in_cset(-1); 6241 } 6242 cur->set_not_young(); 6243 cur->set_evacuation_failed(false); 6244 // The region is now considered to be old. 6245 _old_set.add(cur); 6246 evacuation_info.increment_collectionset_used_after(cur->used()); 6247 } 6248 cur = next; 6249 } 6250 6251 evacuation_info.set_regions_freed(local_free_list.length()); 6252 policy->record_max_rs_lengths(rs_lengths); 6253 policy->cset_regions_freed(); 6254 6255 double end_sec = os::elapsedTime(); 6256 double elapsed_ms = (end_sec - start_sec) * 1000.0; 6257 6258 if (non_young) { 6259 non_young_time_ms += elapsed_ms; 6260 } else { 6261 young_time_ms += elapsed_ms; 6262 } 6263 6264 update_sets_after_freeing_regions(pre_used, &local_free_list, 6265 NULL /* old_proxy_set */, 6266 NULL /* humongous_proxy_set */, 6267 false /* par */); 6268 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms); 6269 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms); 6270 } 6271 6272 // This routine is similar to the above but does not record 6273 // any policy statistics or update free lists; we are abandoning 6274 // the current incremental collection set in preparation of a 6275 // full collection. After the full GC we will start to build up 6276 // the incremental collection set again. 6277 // This is only called when we're doing a full collection 6278 // and is immediately followed by the tearing down of the young list. 6279 6280 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) { 6281 HeapRegion* cur = cs_head; 6282 6283 while (cur != NULL) { 6284 HeapRegion* next = cur->next_in_collection_set(); 6285 assert(cur->in_collection_set(), "bad CS"); 6286 cur->set_next_in_collection_set(NULL); 6287 cur->set_in_collection_set(false); 6288 cur->set_young_index_in_cset(-1); 6289 cur = next; 6290 } 6291 } 6292 6293 void G1CollectedHeap::set_free_regions_coming() { 6294 if (G1ConcRegionFreeingVerbose) { 6295 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " 6296 "setting free regions coming"); 6297 } 6298 6299 assert(!free_regions_coming(), "pre-condition"); 6300 _free_regions_coming = true; 6301 } 6302 6303 void G1CollectedHeap::reset_free_regions_coming() { 6304 assert(free_regions_coming(), "pre-condition"); 6305 6306 { 6307 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6308 _free_regions_coming = false; 6309 SecondaryFreeList_lock->notify_all(); 6310 } 6311 6312 if (G1ConcRegionFreeingVerbose) { 6313 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " 6314 "reset free regions coming"); 6315 } 6316 } 6317 6318 void G1CollectedHeap::wait_while_free_regions_coming() { 6319 // Most of the time we won't have to wait, so let's do a quick test 6320 // first before we take the lock. 6321 if (!free_regions_coming()) { 6322 return; 6323 } 6324 6325 if (G1ConcRegionFreeingVerbose) { 6326 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " 6327 "waiting for free regions"); 6328 } 6329 6330 { 6331 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6332 while (free_regions_coming()) { 6333 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 6334 } 6335 } 6336 6337 if (G1ConcRegionFreeingVerbose) { 6338 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " 6339 "done waiting for free regions"); 6340 } 6341 } 6342 6343 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 6344 assert(heap_lock_held_for_gc(), 6345 "the heap lock should already be held by or for this thread"); 6346 _young_list->push_region(hr); 6347 } 6348 6349 class NoYoungRegionsClosure: public HeapRegionClosure { 6350 private: 6351 bool _success; 6352 public: 6353 NoYoungRegionsClosure() : _success(true) { } 6354 bool doHeapRegion(HeapRegion* r) { 6355 if (r->is_young()) { 6356 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young", 6357 r->bottom(), r->end()); 6358 _success = false; 6359 } 6360 return false; 6361 } 6362 bool success() { return _success; } 6363 }; 6364 6365 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) { 6366 bool ret = _young_list->check_list_empty(check_sample); 6367 6368 if (check_heap) { 6369 NoYoungRegionsClosure closure; 6370 heap_region_iterate(&closure); 6371 ret = ret && closure.success(); 6372 } 6373 6374 return ret; 6375 } 6376 6377 class TearDownRegionSetsClosure : public HeapRegionClosure { 6378 private: 6379 OldRegionSet *_old_set; 6380 6381 public: 6382 TearDownRegionSetsClosure(OldRegionSet* old_set) : _old_set(old_set) { } 6383 6384 bool doHeapRegion(HeapRegion* r) { 6385 if (r->is_empty()) { 6386 // We ignore empty regions, we'll empty the free list afterwards 6387 } else if (r->is_young()) { 6388 // We ignore young regions, we'll empty the young list afterwards 6389 } else if (r->isHumongous()) { 6390 // We ignore humongous regions, we're not tearing down the 6391 // humongous region set 6392 } else { 6393 // The rest should be old 6394 _old_set->remove(r); 6395 } 6396 return false; 6397 } 6398 6399 ~TearDownRegionSetsClosure() { 6400 assert(_old_set->is_empty(), "post-condition"); 6401 } 6402 }; 6403 6404 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) { 6405 assert_at_safepoint(true /* should_be_vm_thread */); 6406 6407 if (!free_list_only) { 6408 TearDownRegionSetsClosure cl(&_old_set); 6409 heap_region_iterate(&cl); 6410 6411 // Need to do this after the heap iteration to be able to 6412 // recognize the young regions and ignore them during the iteration. 6413 _young_list->empty_list(); 6414 } 6415 _free_list.remove_all(); 6416 } 6417 6418 class RebuildRegionSetsClosure : public HeapRegionClosure { 6419 private: 6420 bool _free_list_only; 6421 OldRegionSet* _old_set; 6422 FreeRegionList* _free_list; 6423 size_t _total_used; 6424 6425 public: 6426 RebuildRegionSetsClosure(bool free_list_only, 6427 OldRegionSet* old_set, FreeRegionList* free_list) : 6428 _free_list_only(free_list_only), 6429 _old_set(old_set), _free_list(free_list), _total_used(0) { 6430 assert(_free_list->is_empty(), "pre-condition"); 6431 if (!free_list_only) { 6432 assert(_old_set->is_empty(), "pre-condition"); 6433 } 6434 } 6435 6436 bool doHeapRegion(HeapRegion* r) { 6437 if (r->continuesHumongous()) { 6438 return false; 6439 } 6440 6441 if (r->is_empty()) { 6442 // Add free regions to the free list 6443 _free_list->add_as_tail(r); 6444 } else if (!_free_list_only) { 6445 assert(!r->is_young(), "we should not come across young regions"); 6446 6447 if (r->isHumongous()) { 6448 // We ignore humongous regions, we left the humongous set unchanged 6449 } else { 6450 // The rest should be old, add them to the old set 6451 _old_set->add(r); 6452 } 6453 _total_used += r->used(); 6454 } 6455 6456 return false; 6457 } 6458 6459 size_t total_used() { 6460 return _total_used; 6461 } 6462 }; 6463 6464 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { 6465 assert_at_safepoint(true /* should_be_vm_thread */); 6466 6467 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_free_list); 6468 heap_region_iterate(&cl); 6469 6470 if (!free_list_only) { 6471 _summary_bytes_used = cl.total_used(); 6472 } 6473 assert(_summary_bytes_used == recalculate_used(), 6474 err_msg("inconsistent _summary_bytes_used, " 6475 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT, 6476 _summary_bytes_used, recalculate_used())); 6477 } 6478 6479 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) { 6480 _refine_cte_cl->set_concurrent(concurrent); 6481 } 6482 6483 bool G1CollectedHeap::is_in_closed_subset(const void* p) const { 6484 HeapRegion* hr = heap_region_containing(p); 6485 if (hr == NULL) { 6486 return false; 6487 } else { 6488 return hr->is_in(p); 6489 } 6490 } 6491 6492 // Methods for the mutator alloc region 6493 6494 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 6495 bool force) { 6496 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6497 assert(!force || g1_policy()->can_expand_young_list(), 6498 "if force is true we should be able to expand the young list"); 6499 bool young_list_full = g1_policy()->is_young_list_full(); 6500 if (force || !young_list_full) { 6501 HeapRegion* new_alloc_region = new_region(word_size, 6502 false /* do_expand */); 6503 if (new_alloc_region != NULL) { 6504 set_region_short_lived_locked(new_alloc_region); 6505 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full); 6506 return new_alloc_region; 6507 } 6508 } 6509 return NULL; 6510 } 6511 6512 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 6513 size_t allocated_bytes) { 6514 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6515 assert(alloc_region->is_young(), "all mutator alloc regions should be young"); 6516 6517 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region); 6518 _summary_bytes_used += allocated_bytes; 6519 _hr_printer.retire(alloc_region); 6520 // We update the eden sizes here, when the region is retired, 6521 // instead of when it's allocated, since this is the point that its 6522 // used space has been recored in _summary_bytes_used. 6523 g1mm()->update_eden_size(); 6524 } 6525 6526 HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size, 6527 bool force) { 6528 return _g1h->new_mutator_alloc_region(word_size, force); 6529 } 6530 6531 void G1CollectedHeap::set_par_threads() { 6532 // Don't change the number of workers. Use the value previously set 6533 // in the workgroup. 6534 assert(G1CollectedHeap::use_parallel_gc_threads(), "shouldn't be here otherwise"); 6535 uint n_workers = workers()->active_workers(); 6536 assert(UseDynamicNumberOfGCThreads || 6537 n_workers == workers()->total_workers(), 6538 "Otherwise should be using the total number of workers"); 6539 if (n_workers == 0) { 6540 assert(false, "Should have been set in prior evacuation pause."); 6541 n_workers = ParallelGCThreads; 6542 workers()->set_active_workers(n_workers); 6543 } 6544 set_par_threads(n_workers); 6545 } 6546 6547 void MutatorAllocRegion::retire_region(HeapRegion* alloc_region, 6548 size_t allocated_bytes) { 6549 _g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes); 6550 } 6551 6552 // Methods for the GC alloc regions 6553 6554 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, 6555 uint count, 6556 GCAllocPurpose ap) { 6557 assert(FreeList_lock->owned_by_self(), "pre-condition"); 6558 6559 if (count < g1_policy()->max_regions(ap)) { 6560 HeapRegion* new_alloc_region = new_region(word_size, 6561 true /* do_expand */); 6562 if (new_alloc_region != NULL) { 6563 // We really only need to do this for old regions given that we 6564 // should never scan survivors. But it doesn't hurt to do it 6565 // for survivors too. 6566 new_alloc_region->set_saved_mark(); 6567 if (ap == GCAllocForSurvived) { 6568 new_alloc_region->set_survivor(); 6569 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor); 6570 } else { 6571 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old); 6572 } 6573 bool during_im = g1_policy()->during_initial_mark_pause(); 6574 new_alloc_region->note_start_of_copying(during_im); 6575 return new_alloc_region; 6576 } else { 6577 g1_policy()->note_alloc_region_limit_reached(ap); 6578 } 6579 } 6580 return NULL; 6581 } 6582 6583 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 6584 size_t allocated_bytes, 6585 GCAllocPurpose ap) { 6586 bool during_im = g1_policy()->during_initial_mark_pause(); 6587 alloc_region->note_end_of_copying(during_im); 6588 g1_policy()->record_bytes_copied_during_gc(allocated_bytes); 6589 if (ap == GCAllocForSurvived) { 6590 young_list()->add_survivor_region(alloc_region); 6591 } else { 6592 _old_set.add(alloc_region); 6593 } 6594 _hr_printer.retire(alloc_region); 6595 } 6596 6597 HeapRegion* SurvivorGCAllocRegion::allocate_new_region(size_t word_size, 6598 bool force) { 6599 assert(!force, "not supported for GC alloc regions"); 6600 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForSurvived); 6601 } 6602 6603 void SurvivorGCAllocRegion::retire_region(HeapRegion* alloc_region, 6604 size_t allocated_bytes) { 6605 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes, 6606 GCAllocForSurvived); 6607 } 6608 6609 HeapRegion* OldGCAllocRegion::allocate_new_region(size_t word_size, 6610 bool force) { 6611 assert(!force, "not supported for GC alloc regions"); 6612 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForTenured); 6613 } 6614 6615 void OldGCAllocRegion::retire_region(HeapRegion* alloc_region, 6616 size_t allocated_bytes) { 6617 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes, 6618 GCAllocForTenured); 6619 } 6620 // Heap region set verification 6621 6622 class VerifyRegionListsClosure : public HeapRegionClosure { 6623 private: 6624 FreeRegionList* _free_list; 6625 OldRegionSet* _old_set; 6626 HumongousRegionSet* _humongous_set; 6627 uint _region_count; 6628 6629 public: 6630 VerifyRegionListsClosure(OldRegionSet* old_set, 6631 HumongousRegionSet* humongous_set, 6632 FreeRegionList* free_list) : 6633 _old_set(old_set), _humongous_set(humongous_set), 6634 _free_list(free_list), _region_count(0) { } 6635 6636 uint region_count() { return _region_count; } 6637 6638 bool doHeapRegion(HeapRegion* hr) { 6639 _region_count += 1; 6640 6641 if (hr->continuesHumongous()) { 6642 return false; 6643 } 6644 6645 if (hr->is_young()) { 6646 // TODO 6647 } else if (hr->startsHumongous()) { 6648 _humongous_set->verify_next_region(hr); 6649 } else if (hr->is_empty()) { 6650 _free_list->verify_next_region(hr); 6651 } else { 6652 _old_set->verify_next_region(hr); 6653 } 6654 return false; 6655 } 6656 }; 6657 6658 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index, 6659 HeapWord* bottom) { 6660 HeapWord* end = bottom + HeapRegion::GrainWords; 6661 MemRegion mr(bottom, end); 6662 assert(_g1_reserved.contains(mr), "invariant"); 6663 // This might return NULL if the allocation fails 6664 return new HeapRegion(hrs_index, _bot_shared, mr); 6665 } 6666 6667 void G1CollectedHeap::verify_region_sets() { 6668 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6669 6670 // First, check the explicit lists. 6671 _free_list.verify(); 6672 { 6673 // Given that a concurrent operation might be adding regions to 6674 // the secondary free list we have to take the lock before 6675 // verifying it. 6676 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6677 _secondary_free_list.verify(); 6678 } 6679 _old_set.verify(); 6680 _humongous_set.verify(); 6681 6682 // If a concurrent region freeing operation is in progress it will 6683 // be difficult to correctly attributed any free regions we come 6684 // across to the correct free list given that they might belong to 6685 // one of several (free_list, secondary_free_list, any local lists, 6686 // etc.). So, if that's the case we will skip the rest of the 6687 // verification operation. Alternatively, waiting for the concurrent 6688 // operation to complete will have a non-trivial effect on the GC's 6689 // operation (no concurrent operation will last longer than the 6690 // interval between two calls to verification) and it might hide 6691 // any issues that we would like to catch during testing. 6692 if (free_regions_coming()) { 6693 return; 6694 } 6695 6696 // Make sure we append the secondary_free_list on the free_list so 6697 // that all free regions we will come across can be safely 6698 // attributed to the free_list. 6699 append_secondary_free_list_if_not_empty_with_lock(); 6700 6701 // Finally, make sure that the region accounting in the lists is 6702 // consistent with what we see in the heap. 6703 _old_set.verify_start(); 6704 _humongous_set.verify_start(); 6705 _free_list.verify_start(); 6706 6707 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_free_list); 6708 heap_region_iterate(&cl); 6709 6710 _old_set.verify_end(); 6711 _humongous_set.verify_end(); 6712 _free_list.verify_end(); 6713 } 6714 6715 // Optimized nmethod scanning 6716 6717 class RegisterNMethodOopClosure: public OopClosure { 6718 G1CollectedHeap* _g1h; 6719 nmethod* _nm; 6720 6721 template <class T> void do_oop_work(T* p) { 6722 T heap_oop = oopDesc::load_heap_oop(p); 6723 if (!oopDesc::is_null(heap_oop)) { 6724 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 6725 HeapRegion* hr = _g1h->heap_region_containing(obj); 6726 assert(!hr->continuesHumongous(), 6727 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT 6728 " starting at "HR_FORMAT, 6729 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()))); 6730 6731 // HeapRegion::add_strong_code_root() avoids adding duplicate 6732 // entries but having duplicates is OK since we "mark" nmethods 6733 // as visited when we scan the strong code root lists during the GC. 6734 hr->add_strong_code_root(_nm); 6735 assert(hr->rem_set()->strong_code_roots_list_contains(_nm), 6736 err_msg("failed to add code root "PTR_FORMAT" to remembered set of region "HR_FORMAT, 6737 _nm, HR_FORMAT_PARAMS(hr))); 6738 } 6739 } 6740 6741 public: 6742 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 6743 _g1h(g1h), _nm(nm) {} 6744 6745 void do_oop(oop* p) { do_oop_work(p); } 6746 void do_oop(narrowOop* p) { do_oop_work(p); } 6747 }; 6748 6749 class UnregisterNMethodOopClosure: public OopClosure { 6750 G1CollectedHeap* _g1h; 6751 nmethod* _nm; 6752 6753 template <class T> void do_oop_work(T* p) { 6754 T heap_oop = oopDesc::load_heap_oop(p); 6755 if (!oopDesc::is_null(heap_oop)) { 6756 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 6757 HeapRegion* hr = _g1h->heap_region_containing(obj); 6758 assert(!hr->continuesHumongous(), 6759 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT 6760 " starting at "HR_FORMAT, 6761 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()))); 6762 6763 hr->remove_strong_code_root(_nm); 6764 assert(!hr->rem_set()->strong_code_roots_list_contains(_nm), 6765 err_msg("failed to remove code root "PTR_FORMAT" of region "HR_FORMAT, 6766 _nm, HR_FORMAT_PARAMS(hr))); 6767 } 6768 } 6769 6770 public: 6771 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 6772 _g1h(g1h), _nm(nm) {} 6773 6774 void do_oop(oop* p) { do_oop_work(p); } 6775 void do_oop(narrowOop* p) { do_oop_work(p); } 6776 }; 6777 6778 void G1CollectedHeap::register_nmethod(nmethod* nm) { 6779 CollectedHeap::register_nmethod(nm); 6780 6781 guarantee(nm != NULL, "sanity"); 6782 RegisterNMethodOopClosure reg_cl(this, nm); 6783 nm->oops_do(®_cl); 6784 } 6785 6786 void G1CollectedHeap::unregister_nmethod(nmethod* nm) { 6787 CollectedHeap::unregister_nmethod(nm); 6788 6789 guarantee(nm != NULL, "sanity"); 6790 UnregisterNMethodOopClosure reg_cl(this, nm); 6791 nm->oops_do(®_cl, true); 6792 } 6793 6794 class MigrateCodeRootsHeapRegionClosure: public HeapRegionClosure { 6795 public: 6796 bool doHeapRegion(HeapRegion *hr) { 6797 assert(!hr->isHumongous(), 6798 err_msg("humongous region "HR_FORMAT" should not have been added to collection set", 6799 HR_FORMAT_PARAMS(hr))); 6800 hr->migrate_strong_code_roots(); 6801 return false; 6802 } 6803 }; 6804 6805 void G1CollectedHeap::migrate_strong_code_roots() { 6806 MigrateCodeRootsHeapRegionClosure cl; 6807 double migrate_start = os::elapsedTime(); 6808 collection_set_iterate(&cl); 6809 double migration_time_ms = (os::elapsedTime() - migrate_start) * 1000.0; 6810 g1_policy()->phase_times()->record_strong_code_root_migration_time(migration_time_ms); 6811 } 6812 6813 void G1CollectedHeap::purge_code_root_memory() { 6814 double purge_start = os::elapsedTime(); 6815 G1CodeRootSet::purge_chunks(G1CodeRootsChunkCacheKeepRatio); 6816 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0; 6817 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms); 6818 } 6819 6820 // Mark all the code roots that point into regions *not* in the 6821 // collection set. 6822 // 6823 // Note we do not want to use a "marking" CodeBlobToOopClosure while 6824 // walking the the code roots lists of regions not in the collection 6825 // set. Suppose we have an nmethod (M) that points to objects in two 6826 // separate regions - one in the collection set (R1) and one not (R2). 6827 // Using a "marking" CodeBlobToOopClosure here would result in "marking" 6828 // nmethod M when walking the code roots for R1. When we come to scan 6829 // the code roots for R2, we would see that M is already marked and it 6830 // would be skipped and the objects in R2 that are referenced from M 6831 // would not be evacuated. 6832 6833 class MarkStrongCodeRootCodeBlobClosure: public CodeBlobClosure { 6834 6835 class MarkStrongCodeRootOopClosure: public OopClosure { 6836 ConcurrentMark* _cm; 6837 HeapRegion* _hr; 6838 uint _worker_id; 6839 6840 template <class T> void do_oop_work(T* p) { 6841 T heap_oop = oopDesc::load_heap_oop(p); 6842 if (!oopDesc::is_null(heap_oop)) { 6843 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 6844 // Only mark objects in the region (which is assumed 6845 // to be not in the collection set). 6846 if (_hr->is_in(obj)) { 6847 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id); 6848 } 6849 } 6850 } 6851 6852 public: 6853 MarkStrongCodeRootOopClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id) : 6854 _cm(cm), _hr(hr), _worker_id(worker_id) { 6855 assert(!_hr->in_collection_set(), "sanity"); 6856 } 6857 6858 void do_oop(narrowOop* p) { do_oop_work(p); } 6859 void do_oop(oop* p) { do_oop_work(p); } 6860 }; 6861 6862 MarkStrongCodeRootOopClosure _oop_cl; 6863 6864 public: 6865 MarkStrongCodeRootCodeBlobClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id): 6866 _oop_cl(cm, hr, worker_id) {} 6867 6868 void do_code_blob(CodeBlob* cb) { 6869 nmethod* nm = (cb == NULL) ? NULL : cb->as_nmethod_or_null(); 6870 if (nm != NULL) { 6871 nm->oops_do(&_oop_cl); 6872 } 6873 } 6874 }; 6875 6876 class MarkStrongCodeRootsHRClosure: public HeapRegionClosure { 6877 G1CollectedHeap* _g1h; 6878 uint _worker_id; 6879 6880 public: 6881 MarkStrongCodeRootsHRClosure(G1CollectedHeap* g1h, uint worker_id) : 6882 _g1h(g1h), _worker_id(worker_id) {} 6883 6884 bool doHeapRegion(HeapRegion *hr) { 6885 HeapRegionRemSet* hrrs = hr->rem_set(); 6886 if (hr->continuesHumongous()) { 6887 // Code roots should never be attached to a continuation of a humongous region 6888 assert(hrrs->strong_code_roots_list_length() == 0, 6889 err_msg("code roots should never be attached to continuations of humongous region "HR_FORMAT 6890 " starting at "HR_FORMAT", but has "SIZE_FORMAT, 6891 HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()), 6892 hrrs->strong_code_roots_list_length())); 6893 return false; 6894 } 6895 6896 if (hr->in_collection_set()) { 6897 // Don't mark code roots into regions in the collection set here. 6898 // They will be marked when we scan them. 6899 return false; 6900 } 6901 6902 MarkStrongCodeRootCodeBlobClosure cb_cl(_g1h->concurrent_mark(), hr, _worker_id); 6903 hr->strong_code_roots_do(&cb_cl); 6904 return false; 6905 } 6906 }; 6907 6908 void G1CollectedHeap::mark_strong_code_roots(uint worker_id) { 6909 MarkStrongCodeRootsHRClosure cl(this, worker_id); 6910 if (G1CollectedHeap::use_parallel_gc_threads()) { 6911 heap_region_par_iterate_chunked(&cl, 6912 worker_id, 6913 workers()->active_workers(), 6914 HeapRegion::ParMarkRootClaimValue); 6915 } else { 6916 heap_region_iterate(&cl); 6917 } 6918 } 6919 6920 class RebuildStrongCodeRootClosure: public CodeBlobClosure { 6921 G1CollectedHeap* _g1h; 6922 6923 public: 6924 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) : 6925 _g1h(g1h) {} 6926 6927 void do_code_blob(CodeBlob* cb) { 6928 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL; 6929 if (nm == NULL) { 6930 return; 6931 } 6932 6933 if (ScavengeRootsInCode && nm->detect_scavenge_root_oops()) { 6934 _g1h->register_nmethod(nm); 6935 } 6936 } 6937 }; 6938 6939 void G1CollectedHeap::rebuild_strong_code_roots() { 6940 RebuildStrongCodeRootClosure blob_cl(this); 6941 CodeCache::blobs_do(&blob_cl); 6942 }